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1002.0026
|
steganography is an information hiding application which aims to hide secret data imperceptibly into a commonly used media . unfortunately , the theoretical hiding asymptotical capacity of steganographic systems is not attained by algorithms developed so far . in this paper , we describe a novel coding method based on @xmath0-linear codes that conforms to @xmath1-steganography , that is secret data is embedded into a cover message by distorting each symbol by one unit at most . this method solves some problems encountered by the most efficient methods known today , based on ternary hamming codes . finally , the performance of this new technique is compared with that of the mentioned methods and with the well - known theoretical upper bound .
| 123
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1004.1954
|
using a large sample ( @xmath0 11800 events ) of @xmath1 and @xmath2 decays collected by the cleo - c detector running at the @xmath3 , we measure the helicity basis form factors free from the assumptions of spectroscopic pole dominance and provide new , accurate measurements of the absolute branching fractions for @xmath4 and @xmath5 decays . we find branching fractions which are consistent with previous world averages . our measured helicity basis form factors are consistent with the spectroscopic pole dominance predictions for the three main helicity basis form factors describing @xmath6 decay . the ability to analyze @xmath2 allows us to make the first non - parametric measurements of the mass - suppressed form factor . our result is inconsistent with existing lattice qcd calculations . finally , we measure the form factor that controls non - resonant @xmath7-wave interference with the @xmath6 amplitude and search for evidence of possible additional non - resonant @xmath8- or @xmath9-wave interference with the @xmath10 .
| 165
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1111.5808
|
we generalize kirchhoff s point vortex model of two - dimensional fluid motion to a rotor model which exhibits an inverse cascade by the formation of rotor clusters . a rotor is composed of two vortices with like - signed circulations glued together by an overdamped spring . the model is motivated by a treatment of the vorticity equation representing the vorticity field as a superposition of vortices with elliptic gaussian shapes of variable widths , augmented by a suitable forcing mechanism . the rotor model opens up the way to discuss the energy transport in the inverse cascade on the basis of dynamical systems theory .
| 107
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1112.3147
|
we analyze a high - resolution spectrum of the a3 m star hd27411 . we compare abundances derived from atlas9 model atmospheres with those using the more computationally - intensive atlas12 code . we found very little differences in the abundances , suggesting that atlas9 can be used for moderate chemical peculiarity . our abundances agree well with the predictions of diffusion theory , though for some elements it was necessary to calculate line profiles in non - thermodynamic equilibrium to obtain agreement . we investigate the effective temperatures and luminosities of am / fm stars using synthetic strmgren indices derived from calculated spectra with the atmospheric abundances of hd27411 . we find that the effective temperatures of am / fm stars derived from strmgren photometry are reliable , but the luminosities are probably too low . caution is required when deriving the reddening of these stars owing to line blanketing effects . a comparison of the relative proportions of pulsating and non - pulsating am stars with @xmath0 scuti stars shows quite clearly that there is no significant decrease of helium in the driving zone , contrary to current models of diffusion . [ firstpage ] stars : chemically peculiar stars : individual : hd27411 stars : abundances
| 209
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1608.00245
|
we study the spin resonance in superconducting state of iron - based materials within multiband models with two unequal gaps , @xmath0 and @xmath1 , on different fermi surface pockets . we show that due to the indirect nature of the gap entering the spin susceptibility at the nesting wave vector @xmath2 the total gap @xmath3 in the bare susceptibility is determined by the sum of gaps on two different fermi surface sheets connected by @xmath2 . for the fermi surface geometry characteristic to the most of iron pnictides and chalcogenides , the indirect gap is either @xmath4 or @xmath5 . in the @xmath6 state , spin excitations below @xmath3 are absent unless additional scattering mechanisms are assumed . the spin resonance appears in the @xmath7 superconducting state at frequency @xmath8 . comparison with available inelastic neutron scattering data confirms that what is seen is the true spin resonance and not a peak inherent to the @xmath6 state .
| 159
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1510.01883
|
we introduce a two - dimensional short - range correlated disorder that is the natural generalization of the well - known one - dimensional dual random dimer model [ phys . rev . lett * 65 * , 88 ( 1990 ) ] . we demonstrate that , as in one dimension , this model induces a localization - delocalization transition in the single - particle spectrum . moreover we show that the effect of such a disorder on a weakly - interacting boson gas is to enhance the condensate spatial homogeneity and delocalisation , and to increase the condensate fraction around an effective resonance of the two - dimensional dual dimers . this study proves that short - range correlations of a disordered potential can enhance the quantum coherence of a weakly - interacting many - body system .
| 140
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nlin0508033
|
we study the predictability of emergent phenomena in complex systems . using nearest neighbor , one - dimensional cellular automata ( ca ) as an example , we show how to construct local coarse - grained descriptions of ca in all classes of wolfram s classification . the resulting coarse - grained ca that we construct are capable of emulating the large - scale behavior of the original systems without accounting for small - scale details . several ca that can be coarse - grained by this construction are known to be universal turing machines ; they can emulate any ca or other computing devices and are therefore undecidable . we thus show that because in practice one only seeks coarse - grained information , complex physical systems can be predictable and even decidable at some level of description . the renormalization group flows that we construct induce a hierarchy of ca rules . this hierarchy agrees well with apparent rule complexity and is therefore a good candidate for a complexity measure and a classification method . finally we argue that the large scale dynamics of ca can be very simple , at least when measured by the kolmogorov complexity of the large scale update rule , and moreover exhibits a novel scaling law . we show that because of this large - scale simplicity , the probability of finding a coarse - grained description of ca approaches unity as one goes to increasingly coarser scales . we interpret this large scale simplicity as a pattern formation mechanism in which large scale patterns are forced upon the system by the simplicity of the rules that govern the large scale dynamics .
| 281
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1506.05147
|
we present the results of an imaging observation campaign conducted with the subaru telescope adaptive optics system ( ircs+ao188 ) on 28 gravitationally lensed quasars and candidates ( 23 doubles , 1 quad , 1 possible triple and 3 candidates ) from the sdss quasar lens search . we develop a novel modelling technique that fits analytical and hybrid point spread functions ( psfs ) , while simultaneously measuring the relative astrometry , photometry , as well as the lens galaxy morphology . we account for systematics by simulating the observed systems using separately observed psf stars . the measured relative astrometry is comparable with that typically achieved with the hubble space telescope , even after marginalizing over the psf uncertainty . we model for the first time the quasar host galaxies in 5 systems , without a - priory knowledge of the psf , and show that their luminosities follow the known correlation with the mass of the supermassive black hole . for each system , we obtain mass models far more accurate than those previously published from low - resolution data , and we show that in our sample of lensing galaxies the observed light profile is more elliptical than the mass , for ellipticity @xmath0 . we also identify eight doubles for which the sources of external and internal shear are more reliably separated , and should therefore be prioritized in monitoring campaigns aimed at measuring time - delays in order to infer the hubble constant . [ firstpage ] adaptive optics gravitationally lensed quasars quasar host galaxies
| 261
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1202.6679
|
the decay of a false vacuum of unbroken @xmath0@xmath1@xmath2 symmetry is an intriguing and testable mechanism to generate the initial conditions of the hot early universe . if @xmath0@xmath1@xmath2 is broken at the grand unification scale , the false vacuum phase yields hybrid inflation , ending in tachyonic preheating . the dynamics of the @xmath0@xmath1@xmath2 breaking higgs field and thermal processes produce an abundance of heavy neutrinos whose decays generate entropy , baryon asymmetry and gravitino dark matter . we study the phase transition for the full supersymmetric abelian higgs model . for the subsequent reheating process we give a detailed time - resolved description of all particle abundances . the competition of cosmic expansion and entropy production leads to an intermediate period of constant ` reheating ' temperature , during which baryon asymmetry and dark matter are produced . consistency of hybrid inflation , leptogenesis and gravitino dark matter implies relations between neutrino parameters and superparticle masses . in particular , for a gluino mass of @xmath3 , we find a lower bound on the gravitino mass of @xmath4 . desy 11 - 174 + march 2012 * spontaneous @xmath0@xmath1@xmath2 breaking as + the origin of the hot early universe * w. buchmller , v. domcke , k. schmitz + _ deutsches elektronen - synchrotron desy , 22607 hamburg , germany _ .
| 224
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1701.07203
|
the need to produce accurate estimates of vertex degree in a large network , based on observation of a subnetwork , arises in a number of practical settings . we study a formalized version of this problem , wherein the goal is , given a randomly sampled subnetwork from a large parent network , to estimate the actual degree of the sampled nodes . depending on the sampling scheme , trivial method of moments estimators ( mmes ) can be used . however , the mme is not expected , in general , to use all relevant network information . in this study , we propose a handful of novel estimators derived from a risk - theoretic perspective , which make more sophisticated use of the information in the sampled network . theoretical assessment of the new estimators characterizes under what conditions they can offer improvement over the mme , while numerical comparisons show that when such improvement obtains , it can be substantial . illustration is provided on a human trafficking network .
| 174
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1008.2583
|
determining the size of a maximum independent set of a graph @xmath0 , denoted by @xmath1 , is an np - hard problem . therefore many attempts are made to find upper and lower bounds , or exact values of @xmath2 for special classes of graphs . this paper is aimed toward studying this problem for the class of generalized petersen graphs . we find new upper and lower bounds and some exact values for @xmath3 . with a computer program we have obtained exact values for each @xmath4 . in @xcite it is conjectured that the size of the minimum vertex cover , @xmath5 , is less than or equal to @xmath6 , for all @xmath7 and @xmath8 with @xmath9 . we prove this conjecture for some cases . in particular , we show that if @xmath10 , the conjecture is valid . we checked the conjecture with our table for @xmath11 and it had no inconsistency . finally , we show that for every fixed @xmath8 , @xmath12 can be computed using an algorithm with running time @xmath13 . * keywords * : generalized petersen graphs , independent set , tree decomposition
| 194
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1408.4792
|
accurate forecasting is important for cost - effective and efficient monitoring and control of the renewable energy based power generation . wind based power is one of the most difficult energy to predict accurately , due to the widely varying and unpredictable nature of wind energy . although autoregressive ( ar ) techniques have been widely used to create wind power models , they have shown limited accuracy in forecasting , as well as difficulty in determining the correct parameters for an optimized ar model . in this paper , constriction factor particle swarm optimization ( cf - pso ) is employed to optimally determine the parameters of an autoregressive ( ar ) model for accurate prediction of the wind power output behaviour . appropriate lag order of the proposed model is selected based on akaike information criterion . the performance of the proposed pso based ar model is compared with four well - established approaches ; forward - backward approach , geometric lattice approach , least - squares approach and yule - walker approach , that are widely used for error minimization of the ar model . to validate the proposed approach , real - life wind power data of _ capital wind farm _ was obtained from australian energy market operator . experimental evaluation based on a number of different datasets demonstrate that the performance of the ar model is significantly improved compared with benchmark methods . constriction factor particle swarm optimization ( cf - pso ) , ar model , wind power prediction
| 256
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astro-ph0108412
|
we present a novel , highly efficient algorithm to parallelize @xmath0direct summation method for @xmath1-body problems with individual timesteps on distributed - memory parallel machines such as beowulf clusters . previously known algorithms , in which all processors have complete copies of the @xmath1-body system , has the serious problem that the communication - computation ratio increases as we increase the number of processors , since the communication cost is independent of the number of processors . in the new algorithm , @xmath2 processors are organized as a @xmath3 two - dimensional array . each processor has @xmath4 particles , but the data are distributed in such a way that complete system is presented if we look at any row or column consisting of @xmath5 processors . in this algorithm , the communication cost scales as @xmath6 , while the calculation cost scales as @xmath7 . thus , we can use a much larger number of processors without losing efficiency compared to what was practical with previously known algorithms . _ pacs : 02.60.cb;95.10.ce ; 98.10.+z _ celestial mechanics , stellar dynamics;methods : numerical # 1@xmath8 # 1@xmath9 # 1*[#1 piet ] * # 1*[#1 jun ] * = cmbx10 scaled 2
| 202
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0705.0797
|
we show the asymptotic long - time equivalence of a generic power law waiting time distribution to the mittag - leffler waiting time distribution , characteristic for a time fractional continuous time random walk . this asymptotic equivalence is effected by a combination of rescaling " time and respeeding " the relevant renewal process followed by a passage to a limit for which we need a suitable relation between the parameters of rescaling and respeeding . as far as we know such procedure has been first applied in the 1960s by gnedenko and kovalenko in their theory of thinning " a renewal process . turning our attention to spatially one - dimensional continuous time random walks with a generic power law jump distribution , rescaling " space can be interpreted as a second kind of respeeding " which then , again under a proper relation between the relevant parameters leads in the limit to the space - time fractional diffusion equation . finally , we treat the time fractional drift " process as a properly scaled limit of the counting number of a mittag - leffler renewal process . = 10000 -1.5truecm -0.5truecm = cmr10 = cmr10 at 10 truept -0.75 truecm invited lecture by r. gorenflo at the 373 we - heraeus - seminar on anomalous transport : experimental results and theoretical challenges , physikzentrum bad - honnef ( germany ) , 12 - 16 july 2006 . it will appear in the book _ anomalous transport : foundations and applications _ edited by r. klages , g. radons and i.m sokolov , as chapter 4 , pp . 93 - 127 , wiley - vch , weinheim , germany ( 2008 ) . @xmath0 -2.0truecm = 10000 = 2000 # 11 l = cmbx12 scaled1
| 297
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1312.7701
|
in this paper , we simulate the prompt emission light curves of gamma - ray bursts ( grbs ) within the framework of the internal - collision - induced magnetic reconnection and turbulence ( icmart ) model . this model applies to grbs with a moderately high magnetization parameter @xmath0 in the emission region . we show that this model can produce highly variable light curves with both fast and slow components . the rapid variability is caused by many locally doppler - boosted mini - emitters due to turbulent magnetic reconnection in a moderately high @xmath0 flow . the runaway growth and subsequent depletion of these mini - emitters as a function of time define a broad slow component for each icmart event . a grb light curve is usually composed of multiple icmart events that are fundamentally driven by the erratic grb central engine activity . allowing variations of the model parameters , one is able to reproduce a variety of light curves and the power density spectra as observed .
| 173
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1602.04530
|
in this paper , we show that markov s principle is not derivable in dependent type theory with natural numbers and one universe . one tentative way to prove this would be to remark that markov s principle does not hold in a sheaf model of type theory over cantor space , since markov s principle does not hold for the generic point of this model . it is however not clear how to interpret the universe in a sheaf model @xcite . instead we design an extension of type theory , which intuitively extends type theory by the addition of a generic point of cantor space . we then show the consistency of this extension by a normalization argument . markov s principle does not hold in this extension , and it follows that it can not be proved in type theory .
| 144
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astro-ph0011109
|
we calculate analytically and numerically the dyer - roeder distance in perfect fluid quintessence models and give an accurate fit to the numerical solutions for all the values of the density parameter and the quintessence equation of state . then we apply our solutions to the estimation of @xmath0 from multiple image time delays and find that the inclusion of quintessence modifies sensibly the likelihood distribution of @xmath0 , generally reducing the best estimate with respect to a pure cosmological constant . marginalizing over the other parameters ( @xmath1 and the quintessence equation of state ) , we obtain @xmath2 km / sec / mpc for an empty beam and @xmath3 km / sec / mpc for a filled beam . we also discuss the future prospects for distinguishing quintessence from a cosmological constant with time delays . epsf.tex -.5 in
| 141
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hep-ph0501235
|
we explore the role of soft gluon exchange in heavy quarkonium production at large transverse momentum . we find uncanceled infrared poles at nnlo that are not matched by conventional nrqcd matrix elements . we show , however , that gauge invariance and factorization require that conventional nrqcd production operators be modified to include nonabelian phases or wilson lines . with appropriately modified operators , factorization is restored at nnlo . we also argue that , in the absence of special cancellations , infrared poles at yet higher orders may require the inclusion of additional nonlocal operators , not present in the nrqcd expansion in relative veloctiy . yitp - sb-05 - 01 + * fragmentation , factorization and infrared poles + * in heavy quarkonium production gouranga c. nayak@xmath0 , jian - wei qiu@xmath1 and george sterman@xmath0 _ @xmath0c.n . yang institute for theoretical physics , stony brook university , suny + stony brook , new york 11794 - 3840 , u.s.a . _ _ @xmath1department of physics and astronomy , iowa state university + ames , ia 50011 , u.s.a . _ pacs numbers : 12.38.bx , 12.39.st , 13.87.fh,14.40gx
| 192
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0906.0903
|
the fundamental paradox of the incompatibility of the observed large - scale uniformity of the universe with the fact that the age of the universe is finite is overcome by the introduction of an initial a period of superluminal expansion of space , called cosmic inflation . inflation can also produce the small deviations from uniformity needed for the formation of structures in the universe such as galaxies . this is achieved by the conjunction of inflation with the quantum vacuum , through the so - called particle production process . this mechanism is explained and linked with hawking radiation of black holes . the nature of the particles involved is discussed and the case of using massive vector boson fields instead of scalar fields is presented , with emphasis on its distinct observational signatures . finally , a particular implementation of these ideas is included , which can link the formation of galaxies , the standard model vector bosons and the observed galactic magnetic fields . inflation , particle production , primordial density perturbation , cmb radiation , structure formation
| 181
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astro-ph0612398
|
a small number of double - lobed radio galaxies are found with an additional pair of extended low surface brightness ` wings ' of emission giving them a distinctive ` x'-shaped appearance . one popular explanation for the unusual morphologies posits that the central supermassive black hole ( smbh)/accretion disk system underwent a recent realignment ; in a merger scenario , the active lobes mark the post - merger axis of the resultant system ( e.g. , merritt & ekers 2002 ) . however , this and other interpretations are not well tested on the few ( about one dozen ) known examples . in part to remedy this deficiency , a large sample of winged and x - shaped radio sources is being compiled for a systematic study . an initial sample of 100 new candidates is described as well as some of the follow - up work being pursued to test the different scenarios .
| 157
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0903.5022
|
the worldsheet sigma - model of the superstring in @xmath0 has a one - parameter family of flat connections parametrized by the spectral parameter . the corresponding wilson line is not brst invariant for an open contour , because the brst transformation leads to boundary terms . these boundary terms define a cohomological complex associated to the endpoint of the contour . we study the cohomology of this complex for wilson lines in some infinite - dimensional representations . we find that for these representations the cohomology is nontrivial at the ghost number 2 . this implies that it is possible to define a brst invariant open wilson line . the central point in the construction is the existence of massless vertex operators transforming exactly covariantly under the action of the global symmetry group . in flat space massless vertices transform covariantly up to adding brst exact terms , but in ads it is possible to define vertices so that they transform exactly covariantly . calt-68 2722 * @xmath1 + @xmath1 + symmetries of massless vertex operators in @xmath0 * + + +
| 183
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1510.07343
|
nonreciprocal devices that permit wave transmission in only one direction are indispensible in many fields of science including , e.g. , electronics , optics , acoustics , and thermodynamics . manipulating phonons using such nonreciprocal devices may have a range of applications such as phonon diodes , transistors , switches , etc . one way of achieving nonreciprocal phononic devices is to use materials with strong nonlinear response to phonons . however , it is not easy to obtain the required strong mechanical nonlinearity , especially for few - phonon situations . here , we present a general mechanism to amplify nonlinearity using @xmath0-symmetric structures , and show that an on - chip micro - scale phonon diode can be fabricated using a @xmath0-symmetric mechanical system , in which a lossy mechanical - resonator with very weak mechanical nonlinearity is coupled to a mechanical resonator with mechanical gain but no mechanical nonlinearity . when this coupled system transits from the @xmath0-symmetric regime to the broken-@xmath0-symmetric regime , the mechanical nonlinearity is transferred from the lossy resonator to the one with gain , and the effective nonlinearity of the system is significantly enhanced . this enhanced mechanical nonlinearity is almost lossless because of the gain - loss balance induced by the @xmath0-symmetric structure . such an enhanced lossless mechanical nonlinearity is then used to control the direction of phonon propagation , and can greatly decrease ( by over three orders of magnitude ) the threshold of the input - field intensity necessary to observe the unidirectional phonon transport . we propose an experimentally realizable lossless low - threshold phonon diode of this type . our study opens up new perspectives for constructing on - chip few - phonon devices and hybrid phonon - photon components .
| 295
|
1509.00536
|
in this paper , we study the problem of stabilizing continuous - time switched linear systems with quantized output feedback . we assume that the observer and the control gain are given for each mode . also , the plant mode is known to the controller and the quantizer . extending the result in the non - switched case , we develop an update rule of the quantizer to achieve asymptotic stability of the closed - loop system under the average dwell - time assumption . to avoid quantizer saturation , we adjust the quantizer at every switching time . switched systems , quantized control , output feedback stabilization .
| 110
|
1111.3413
|
in this paper , we study the unconditional security of the so - called measurement device independent quantum key distribution ( mdiqkd ) with the basis - dependent flaw in the context of phase encoding schemes . we propose two schemes for the phase encoding , the first one employs a phase locking technique with the use of non - phase - randomized coherent pulses , and the second one uses conversion of standard bb84 phase encoding pulses into polarization modes . we prove the unconditional security of these schemes and we also simulate the key generation rate based on simple device models that accommodate imperfections . our simulation results show the feasibility of these schemes with current technologies and highlight the importance of the state preparation with good fidelity between the density matrices in the two bases . since the basis - dependent flaw is a problem not only for mdiqkd but also for standard qkd , our work highlights the importance of an accurate signal source in practical qkd systems . + * note : we include the erratum of this paper in appendix c. the correction does not affect the validity of the main conclusions reported in the paper , which is the importance of the state preparation in mdiqkd and the fact that our schemes can generate the key with the practical channel mode that we have assumed . *
| 234
|
1111.5190
|
we study the gravity dual of four dimensional pure yang - mills theory through d4 branes , as proposed by witten ( holographic qcd ) . in this holographic qcd , it has been widely believed that the confinement phase in the pure yang - mills theory corresponds to the solitonic d4 brane in gravity and the deconfinement phase corresponds to the black d4 brane . we inspect this conjecture carefully and show that the correspondence between the black d4 brane and the deconfinement phase is not correct . instead , by using a slightly different set up , we find an alternative gravity solution called `` localized soliton '' , which would be properly related to the deconfinement phase . in this case , the confinement / deconfinement transition is realized as a gregory - laflamme type transition . we find that our proposal naturally explains several known properties of qcd . tifr / th/11 - 49 + cctp-2011 - 39 # 1([#1 ] )
| 166
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1205.5975
|
we present a prototypical linear algebra compiler that automatically exploits domain - specific knowledge to generate high - performance algorithms . the input to the compiler is a target equation together with knowledge of both the structure of the problem and the properties of the operands . the output is a variety of high - performance algorithms , and the corresponding source code , to solve the target equation . our approach consists in the decomposition of the input equation into a sequence of library - supported kernels . since in general such a decomposition is not unique , our compiler returns not one but a number of algorithms . the potential of the compiler is shown by means of its application to a challenging equation arising within the _ genome - wide association study_. as a result , the compiler produces multiple `` best '' algorithms that outperform the best existing libraries .
| 154
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hep-ph0611185
|
one of the most straightforward ways to address the flavor problem of low - energy supersymmetry is to arrange for the scalar soft terms to vanish simultaneously at a scale @xmath0 much larger than the electroweak scale . this occurs naturally in a number of scenarios , such as no - scale models , gaugino mediation , and several models with strong conformal dynamics . unfortunately , the most basic version of this approach that incorporates gaugino mass unification and zero scalar masses at the grand unification scale is not compatible with collider and dark matter constraints . however , experimental constraints can be satisfied if we exempt the higgs bosons from flowing to zero mass value at the high scale . we survey the theoretical constructions that allow this , and investigate the collider and dark matter consequences . a generic feature is that the sleptons are relatively light . because of this , these models frequently give a significant contribution to the anomalous magnetic moment of the muon , and neutralino - slepton coannihilation can play an important role in obtaining an acceptable dark matter relic density . furthermore , the light sleptons give rise to a large multiplicity of lepton events at colliders , including a potentially suggestive clean trilepton signal at the tevatron , and a substantial four lepton signature at the lhc . mctp-06 - 32 + higgs boson exempt no - scale supersymmetry + and its collider and cosmology implications + jason l. evans , david e. morrissey , james d. wells + michigan center for theoretical physics ( mctp ) + physics department , university of michigan , ann arbor , mi 48109
| 280
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1206.2872
|
we present electrical data of silicon single electron devices fabricated with cmos techniques and protocols . the easily tuned devices show clean coulomb diamonds at @xmath0 mk and charge offset drift of 0.01 e over eight days . in addition , the devices exhibit robust transistor characteristics including uniformity within about 0.5 v in the threshold voltage , gate resistances greater than 10 g@xmath1 , and immunity to dielectric breakdown in electric fields as high as @xmath2 mv / cm . these results highlight the benefits in device performance of a fully cmos process for single electron device fabrication .
| 100
|
0803.3089
|
here we show that a particular one - parameter generalization of the exponential function is suitable to unify most of the popular one - species discrete population dynamics models into a simple formula . a physical interpretation is given to this new introduced parameter in the context of the continuous richards model , which remains valid for the discrete case . from the discretization of the continuous richards model ( generalization of the gompertz and verhuslt models ) , one obtains a generalized logistic map and we briefly study its properties . notice , however that the physical interpretation for the introduced parameter persists valid for the discrete case . next , we generalize the ( scramble competition ) @xmath0-ricker discrete model and analytically calculate the fixed points as well as their stability . in contrast to previous generalizations , from the generalized @xmath0-ricker model one is able to retrieve either scramble or contest models . complex systems , population dynamics ( ecology ) , nonlinear dynamics 89.75.-k , 87.23.-n , 87.23.cc , 05.45.-a
| 174
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0802.2657
|
a major goal of upcoming experiments measuring the cosmic microwave background radiation ( cmbr ) is to reveal the subtle signature of inflation in the polarization pattern which requires unprecedented sensitivity and control of systematics . since the sensitivity of single receivers has reached fundamental limits future experiments will take advantage of large receiver arrays in order to significantly increase the sensitivity . here we introduce the q / u imaging experiment ( quiet ) which will use hemt - based receivers in chip packages at 90(40 ) ghz in the atacama desert . data taking is planned for the beginning of 2008 with prototype arrays of 91(19 ) receivers , an expansion to 1000 receivers is foreseen . with the two frequencies and a careful choice of scan regions there is the promise of effectively dealing with foregrounds and reaching a sensitivity approaching 10@xmath0 for the ratio of the tensor to scalar perturbations . [ 1999/12/01 v1.4c il nuovo cimento ]
| 162
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cond-mat0404409
|
we study ab@xmath0 miktoarm star block copolymers in the strong segregation limit , focussing on the role that the ab interface plays in determining the phase behavior . we develop an extension of the kinked - path approach which allows us to explore the energetic dependence on interfacial shape . we consider a one - parameter family of interfaces to study the columnar to lamellar transition in asymmetric stars . we compare with recent experimental results . we discuss the stability of the a15 lattice of sphere - like micelles in the context of interfacial energy minimization . we corroborate our theory by implementing a numerically exact self - consistent field theory to probe the phase diagram and the shape of the ab interface .
| 125
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1210.6011
|
this paper is motivated by brolin s theorem . the phenomenon we wish to demonstrate is as follows : if @xmath0 is a holomorphic correspondence on @xmath1 , then ( under certain conditions ) @xmath0 admits a measure @xmath2 such that , for any point @xmath3 drawn from a `` large '' open subset of @xmath1 , @xmath2 is the weak@xmath4-limit of the normalised sums of point masses carried by the pre - images of @xmath3 under the iterates of @xmath0 . let @xmath5 denote the transpose of @xmath0 . under the condition @xmath6 , where @xmath7 denotes the topological degree , the above phenomenon was established by dinh and sibony . we show that the support of this @xmath2 is disjoint from the normality set of @xmath0 . there are many interesting correspondences on @xmath1 for which @xmath8 . examples are the correspondences introduced by bullett and collaborators . when @xmath8 , equidistribution can not be expected to the full extent of brolin s theorem . however , we prove that when @xmath0 admits a repeller , the above analogue of equidistribution holds true .
| 186
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1508.06331
|
we present a method for calculating precise distances to asteroids using only two nights of data from a single location far too little for an orbit by exploiting the angular reflex motion of the asteroids due to earth s axial rotation . we refer to this as the rotational reflex velocity method . while the concept is simple and well - known , it has not been previously exploited for surveys of main - belt asteroids . we offer a mathematical development , estimates of the errors of the approximation , and a demonstration using a sample of 197 asteroids observed for two nights with a small , 0.9-meter telescope . this demonstration used digital tracking to enhance detection sensitivity for faint asteroids , but our distance determination works with any detection method . forty - eight asteroids in our sample had known orbits prior to our observations , and for these we demonstrate a mean fractional error of only 1.6% between the distances we calculate and those given in ephemerides from the minor planet center . in contrast to our two - night results , distance determination by fitting approximate orbits requires observations spanning 710 nights . once an asteroid s distance is known , its absolute magnitude and size ( given a statistically - estimated albedo ) may immediately be calculated . our method will therefore greatly enhance the efficiency with which 4-meter and larger telescopes can probe the size distribution of small ( e.g. 100 meter ) main belt asteroids . this distribution remains poorly known , yet encodes information about the collisional evolution of the asteroid belt and hence the history of the solar system .
| 280
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0912.2875
|
for the statistics of global observables in disordered systems , we discuss the matching between typical fluctuations and large deviations . we focus on the statistics of the ground state energy @xmath0 in two types of disordered models : ( i ) for the directed polymer of length @xmath1 in a two - dimensional medium , where many exact results exist ( ii ) for the sherrington - kirkpatrick spin - glass model of @xmath1 spins , where various possibilities have been proposed . here we stress that , besides the behavior of the disorder - average @xmath2 and of the standard deviation @xmath3 that defines the fluctuation exponent @xmath4 , it is very instructive to study the full probability distribution @xmath5 of the rescaled variable @xmath6 : ( a ) numerically , the convergence towards @xmath5 is usually very rapid , so that data on rather small sizes but with high statistics allow to measure the two tails exponents @xmath7 defined as @xmath8 . in the generic case @xmath9 , this leads to explicit non - trivial terms in the asymptotic behaviors of the moments @xmath10 of the partition function when the combination @xmath11 $ ] becomes large ( b ) simple rare events arguments can usually be found to obtain explicit relations between @xmath7 and @xmath4 . these rare events usually correspond to anomalous large deviation properties of the generalized form @xmath12 ( the usual large deviations formalism corresponds to @xmath13 ) . # 1#2 # 1#2
| 249
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astro-ph0104054
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grs 1915 + 105 was observed by the _ cgro_/osse 9 times in 1995 - 2000 , and 8 of those observations were simultaneous with those by _ rxte_. we present an analysis of all of the osse data and of two _ rxte_-osse spectra with the lowest and highest x - ray fluxes . the osse data show a power - law like spectrum extending up to @xmath0 kev without any break . we interpret this emission as strong evidence for the presence of non - thermal electrons in the source . the broad - band spectra can not be described by either thermal or bulk - motion comptonization , whereas they are well described by comptonization in hybrid thermal / non - thermal plasmas .
| 127
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astro-ph9901059
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we present a new analysis of the far - ir emission at high galactic latitude based on cobe and hi data . a decomposition of the far - ir emission over the hi , h@xmath0 and h@xmath1 galactic gas components and the cosmic far infrared background ( cfirb ) is described . + for the first time the far - ir emission of dust associated with the warm ionised medium ( wim ) is evidenced . this component determined on about 25@xmath2 of the sky is detected at a 10@xmath3 level in the [ 200 , 350 ] @xmath4 band . the best representation of the wim dust spectrum is obtained for a temperature of 29.1 k and an emissivity law @xmath5 3.8 @xmath6 0.8 @xmath7 @xmath8 . with a spectral index equal to 2 , the emissivity law becomes @xmath5 1.0 @xmath6 0.2 @xmath9 @xmath8 , with a temperature of 20 k , which is significantly higher than the temperature of dust associated with hi gas . the variation in the dust spectrum from the hi to the wim component can be explained by only changing the upper cutoff of the big grain size distribution from 0.1 @xmath4 to 30 nm . + the detection of ir emission of dust in the wim significantly decreases the intensity of the cfirb , especially around 200 @xmath4 which corresponds to the peak of energy . +
| 235
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0809.3665
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the x - ray imaging spectrometer ( xis ) on board the suzaku satellite is an x - ray ccd camera system that has superior performance such as a low background , high quantum efficiency , and good energy resolution in the 0.212 kev band . because of the radiation damage in orbit , however , the charge transfer inefficiency ( cti ) has increased , and hence the energy scale and resolution of the xis has been degraded since the launch of july 2005 . the ccd has a charge injection structure , and the cti of each column and the pulse - height dependence of the cti are precisely measured by a checker flag charge injection ( cfci ) technique . our precise cti correction improved the energy resolution from 230 ev to 190 ev at 5.9 kev in december 2006 . this paper reports the cti measurements with the cfci experiments in orbit . using the cfci results , we have implemented the time - dependent energy scale and resolution to the suzaku calibration database .
| 179
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astro-ph0611918
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we present a new diagnostic diagram for mid - infrared spectra of infrared galaxies based on the equivalent width of the 6.2@xmath0 m pah emission feature and the strength of the 9.7@xmath0 m silicate feature . based on the position in this diagram we classify galaxies into 9 classes ranging from continuum - dominated agn hot dust spectra and pah - dominated starburst spectra to absorption - dominated spectra of deeply obscured galactic nuclei . we find that galaxies are systematically distributed along two distinct branches : one of agn and starburst - dominated spectra and one of deeply obscured nuclei and starburst - dominated spectra . the separation into two branches likely reflects a fundamental difference in the dust geometry in the two sets of sources : clumpy versus non - clumpy obscuration . spectra of ulirgs are found along the full length of both branches , reflecting the diverse nature of the ulirg family .
| 157
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1511.00837
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the nonequilibrium dynamical behavior and structure formation of end - functionalized semiflexible polymer suspensions under flow are investigated by mesoscale hydrodynamic simulations . the hybrid simulation approach combines the multiparticle collision dynamics method for the fluid , which accounts for hydrodynamic interactions , with molecular dynamics simulations for the semiflexible polymers . in equilibrium , various kinds of scaffold - like network structures are observed , depending on polymer flexibility and end - attraction strength . we investigate the flow behavior of the polymer networks under shear and analyze their nonequilibrium structural and rheological properties . the scaffold structure breaks up and densified aggregates are formed at low shear rates , while the structural integrity is completely lost at high shear rates . we provide a detailed analysis of the shear - rate - dependent flow - induced structures . the studies provide a deeper understanding of the formation and deformation of network structures in complex materials .
| 158
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1606.04401
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* conformal field theory ( cft ) has been extremely successful in describing large - scale universal effects in one - dimensional ( 1d ) systems at quantum critical points . unfortunately , its applicability in condensed matter physics has been limited to situations in which the bulk is uniform because cft describes low - energy excitations around some energy scale , taken to be constant throughout the system . however , in many experimental contexts , such as quantum gases in trapping potentials and in several out - of - equilibrium situations , systems are strongly inhomogeneous . we show here that the powerful cft methods can be extended to deal with such 1d situations , providing a few concrete examples for non - interacting fermi gases . the system s inhomogeneity enters the field theory action through parameters that vary with position ; in particular , the metric itself varies , resulting in a cft in curved space . this approach allows us to derive exact formulas for entanglement entropies which were not known by other means . * ' '' '' ' '' ''
| 187
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hep-lat0208077
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i review present challenges that qcd in extreme environments presents to lattice gauge theory . recent data and impressions from rhic are emphasized . physical pictures of heavy ion wavefunctions , collisions and the generation of the quark gluon plasma are discussed , with an eye toward engaging the lattice and its numerical methods in more interaction with the experimental and phenomenological developments . controversial , but stimulating scenarios which can be confirmed or dismissed by lattice methods are covered . in the second half of the talk , several promising developments presented at the conference lattice 2002 are reviewed .
| 101
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hep-ph9710463
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we analyze recent results of su(3 ) lattice qcd calculations with a phenomenological parametrization for the quark - gluon plasma equation of state based on a quasi - particle picture with massive quarks and gluons . at high temperature we obtain a good fit to the lattice data using perturbative thermal quark and gluon masses from an improved htl scheme . at temperatures close to the confinement phase transition the fitted masses increase above the perturbative value , and a non - zero ( but small ) bag constant is required to fit the lattice data . = 7.2pt = 7.2pt 14.5pt
| 102
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1502.03264
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the `` problem of time '' in present physics substantially consists in the fact that a straightforward quantization of the general relativistic evolution equation and constraints generates for the universe wave function the wheeler - de witt equation , which describes a static universe . page and wootters considered the fact that there exist states of a system composed by entangled subsystems that are stationary , but one can interpret the component subsystems as evolving : this leads them to suppose that the global state of the universe can be envisaged as one of this static entangled state , whereas the state of the subsystems can evolve . here we synthetically present an experiment , based on pdc polarization entangled photons , that shows a practical example where this idea works , i.e. a subsystem of an entangled state works as a `` clock '' of another subsystem .
| 149
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1511.02682
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on a minute - to - minute basis people undergo numerous fluid interactions with objects that barely register on a conscious level . recent neuroscientific research demonstrates that humans have a fixed size prior for salient objects . this suggests that a salient object in 3d undergoes a consistent transformation such that people s visual system perceives it with an approximately fixed size . this finding indicates that there exists a consistent egocentric object prior that can be characterized by shape , size , depth , and location in the first person view . in this paper , we develop an egoobject representation , which encodes these characteristics by incorporating shape , location , size and depth features from an egocentric rgbd image . we empirically show that this representation can accurately characterize the egocentric object prior by testing it on an egocentric rgbd dataset for three tasks : the 3d saliency detection , future saliency prediction , and interaction classification . this representation is evaluated on our new egocentric rgbd saliency dataset that includes various activities such as cooking , dining , and shopping . by using our egoobject representation , we outperform previously proposed models for saliency detection ( relative @xmath0 improvement for 3d saliency detection task ) on our dataset . additionally , we demonstrate that this representation allows us to predict future salient objects based on the gaze cue and classify people s interactions with objects .
| 241
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1309.1246
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recently , the school of takemura and takayama have developed a quite interesting minimization method called _ holonomic gradient descent method _ ( hgd ) . it works by a mixed use of pfaffian differential equation satisfied by an objective holonomic function and an iterative optimization method . they successfully applied the method to several maximum likelihood estimation ( mle ) problems , which have been intractable in the past . on the other hand , in statistical models , it is not rare that parameters are constrained and therefore the mle with constraints has been surely one of fundamental topics in statistics . in this paper we develop hgd with constraints for mle . * holonomic decent minimization method for restricted maximum likelihood estimation * + rieko sakurai@xmath0 , and toshio sakata @xmath1 + @xmath0 _ graduate school of medicine , kurume university 67 asahimachi , kurume 830 - 0011 , japan _ + @xmath1 _ faculty of design human science , kyushu university , 4 - 9 - 1 shiobaru minami - ku , fukuoka 815 - 8540 , japan _ + email : a213gm009s@std.kurume-u.ac.jp _ key words : holonomic gradinet descent method , newton - raphson method with penalty function , von mises - fisher distribution _
| 210
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1308.5923
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we develop a model which can be used to analyse the scenario of exploring quantum network with a distracted sense of direction . using this model we analyse the behaviour of quantum mobile agents operating with non - adaptive and adaptive strategies which can be employed in this scenario . we introduce the notion of node visiting suitable for analysing quantum superpositions of states by distinguishing between visiting and attaining a position . we show that without a proper model of adaptiveness , it is not possible for the party representing the distraction in the sense of direction , to obtain the results analogous to the classical case . moreover , with additional control resources the total number of attained positions is maintained if the number of visited positions is strictly limited . + keywords : quantum mobile agents ; quantum networks ; two - person quantum games = 1
| 150
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1503.04865
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a genuine feature of projective quantum measurements is that they inevitably alter the mean energy of the observed system if the measured quantity does not commute with the hamiltonian . compared to the classical case , jacobs proved that this additional energetic cost leads to a stronger bound on the work extractable after a single measurement from a system initially in thermal equilibrium [ phys . rev . a 80 , 012322 ( 2009 ) ] . here , we extend this bound to a large class of feedback - driven quantum engines operating periodically and in finite time . the bound thus implies a natural definition for the efficiency of information to work conversion in such devices . for a simple model consisting of a laser - driven two - level system , we maximize the efficiency with respect to the observable whose measurement is used to control the feedback operations . we find that the optimal observable typically does not commute with the hamiltonian and hence would not be available in a classical two level system . this result reveals that periodic feedback engines operating in the quantum realm can exploit quantum coherences to enhance efficiency . = 1
| 201
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astro-ph0511194
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one of the outstanding unsolved riddles of nuclear astrophysics is the origin of the so called `` p - process '' nuclei from a = 92 to 126 . both the lighter and heavier @xmath0-process nuclei are adequately produced in the neon and oxygen shells of ordinary type ii supernovae , but the origin of these intermediate isotopes , especially @xmath1mo and @xmath2ru , has long been mysterious . here we explore the production of these nuclei in the neutrino - driven wind from a young neutron star . we consider such early times that the wind still contains a proton excess because the rates for @xmath3 and positron captures on neutrons are faster than those for the inverse captures on protons . following a suggestion by @xcite , we also include the possibility that , in addition to the protons , @xmath4-particles , and heavy seed , a small flux of neutrons is maintained by the reaction p(@xmath5n . this flux of neutrons is critical in bridging the long waiting points along the path of the @xmath6-process by ( n , p ) and ( n,@xmath7 ) reactions . using the unmodified ejecta histories from a recent two - dimensional supernova model by @xcite , we find synthesis of @xmath0-rich nuclei up to @xmath8pd . however , if the entropy of these ejecta is increased by a factor of two , the synthesis extends to @xmath9te . still larger increases in entropy , that might reflect the role of magnetic fields or vibrational energy input neglected in the hydrodynamical model , result in the production of numerous @xmath10- , @xmath11- , and @xmath0-process nuclei up to a @xmath12 170 , even in winds that are proton - rich .
| 290
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1309.2701
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we consider sojourn or response times in processor - shared queues that have a finite population of potential users . computing the response time of a tagged customer involves solving a finite system of linear odes . writing the system in matrix form , we study the eigenvectors and eigenvalues in the limit as the size of the matrix becomes large . this corresponds to finite population models where the total population is @xmath0 . using asymptotic methods we reduce the eigenvalue problem to that of a standard differential equation , such as the hermite equation . the dominant eigenvalue leads to the tail of a customer s sojourn time distribution . + * keywords : * finite population , processor sharing , eigenvalue , eigenvector , asymptotics .
| 129
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astro-ph0107377
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transition probabilities governing the interaction of energy packets and matter are derived that allow monte carlo nlte transfer codes to be constructed without simplifying the treatment of line formation . these probabilities are such that the monte carlo calculation asymptotically recovers the local emissivity of a gas in statistical equilibrium . numerical experiments with one - point statistical equilibrium problems for fe ii and hydrogen confirm this asymptotic behaviour . in addition , the resulting monte carlo emissivities are shown to be far less sensitive to errors in the populations of the emitting levels than are the values obtained with the basic emissivity formula .
| 105
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cond-mat0406435
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temperature- and field - dependent hall effect measurements are reported for ybagge , a heavy fermion compound exhibiting a field - induced quantum phase transition , and for two other closely related members of the ragge series : a non - magnetic analogue , luagge and a representative , good local moment , magnetic material , tmagge . whereas the temperature dependent hall coefficient of ybagge shows behavior similar to what has been observed in a number of heavy fermion compounds , the low temperature , field - dependent measurements reveal well defined , sudden changes with applied field ; in specific for @xmath0 a clear local maximum that sharpens as temperature is reduced below 2 k and that approaches a value of 45 koe - a value that has been proposed as the @xmath1 quantum critical point . similar behavior was observed for @xmath2 where a clear minimum in the field - dependent hall resistivity was observed at low temperatures . although at our base temperatures it is difficult to distinguish between the field - dependent behavior predicted for ( i ) diffraction off a critical spin density wave or ( ii ) breakdown in the composite nature of the heavy electron , for both field directions there is a distinct temperature dependence of a feature that can clearly be associated with a field - induced quantum critical point at @xmath1 persisting up to at least 2 k.
| 239
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quant-ph0409213
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we propose and analyse simple deterministic algorithms that can be used to construct machines that have primitive learning capabilities . we demonstrate that locally connected networks of these machines can be used to perform blind classification on an event - by - event basis , without storing the information of the individual events . we also demonstrate that properly designed networks of these machines exhibit behavior that is usually only attributed to quantum systems . we present networks that simulate quantum interference on an event - by - event basis . in particular we show that by using simple geometry and the learning capabilities of the machines it becomes possible to simulate single - photon interference in a mach - zehnder interferometer . the interference pattern generated by the network of deterministic learning machines is in perfect agreement with the quantum theoretical result for the single - photon mach - zehnder interferometer . to illustrate that networks of these machines are indeed capable of simulating quantum interference we simulate , event - by - event , a setup involving two chained mach - zehnder interferometers . we show that also in this case the simulation results agree with quantum theory . # 1 # 1#1 # 1#1 # 1#1 # 1#2#1 # 2 # 1([#1 ] )
| 217
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0707.0636
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we update the constraints on new - physics contributions to @xmath0 processes from the generalized unitarity triangle analysis , including the most recent experimental developments . based on these constraints , we derive upper bounds on the coefficients of the most general @xmath1 effective hamiltonian . these upper bounds can be translated into lower bounds on the scale of new physics that contributes to these low - energy effective interactions . we point out that , due to the enhancement in the renormalization group evolution and in the matrix elements , the coefficients of non - standard operators are much more constrained than the coefficient of the operator present in the standard model . therefore , the scale of new physics in models that generate new @xmath1 operators , such as next - to - minimal flavour violation , has to be much higher than the scale of minimal flavour violation , and it most probably lies beyond the reach of direct searches at the lhc .
| 167
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1609.00665
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we propose a @xmath0-symmetrically deformed version of the graphene tight - binding model under a magnetic field . we analyze the structure of the spectra and the eigenvectors of the hamiltonians around the @xmath1 and @xmath2 points , both in the @xmath0-symmetric and @xmath0-broken regions . in particular we show that the presence of the deformation parameter @xmath3 produces several interesting consequences , including the asymmetry of the zero - energy states of the hamiltonians and the breakdown of the completeness of the eigenvector sets . we also discuss the biorthogonality of the eigenvectors , which turns out to be different in the @xmath0-symmetric and @xmath0-broken regions . * @xmath0-symmetric graphene under a magnetic field * + fabio bagarello + dipartimento di energia , ingegneria dellinformazione e modelli matematici , + facolt di ingegneria , universit di palermo , + i-90128 palermo , italy + e - mail : fabio.bagarello@unipa.it + home page : www.unipa.it/fabio.bagarello naomichi hatano + institute of industrial science , university of tokyo , + komaba 4 - 6 - 1 , meguro , tokyo 153 - 8505 , japan + e - mail : hatano@iis.u-tokyo.ac.jp +
| 190
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astro-ph0604257
|
we present high resolution , mid - infrared images toward three hot molecular cores signposted by methanol maser emission ; g173.49 + 2.42 ( s231 , s233ir ) , g188.95 + 0.89 ( s252 , afgl-5180 ) and g192.60 - 0.05 ( s255ir ) . each of the cores was targeted with michelle on gemini north using 5 filters from 7.9 to 18.5 @xmath0 m . we find each contains both large regions of extended emission and multiple , luminous point sources which , from their extremely red colours ( @xmath1 ) , appear to be embedded young stellar objects . the closest angular separations of the point sources in the three regions are 0.79 , 1.00 and 3.33@xmath2 corresponding to linear separations of 1,700 , 1,800 and 6,000au respectively . the methanol maser emission is found closest to the brightest mir point source ( within the assumed 1@xmath2 pointing accuracy ) . mass and luminosity estimates for the sources range from 3 - 22 m@xmath3 and 50 - 40,000 l@xmath3 . assuming the mir sources are embedded objects and the observed gas mass provides the bulk of the reservoir from which the stars formed , it is difficult to generate the observed distributions for the most massive cluster members from the gas in the cores using a standard form of the imf . masers stars : formation techniques : high angular resolution stars : early type stars : mass function infrared : stars .
| 245
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cond-mat0103620
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the ground state and excited state properties of the perovskite lamno@xmath0 , the mother material of colossal magnetoresistance manganites , are calculated based on the generalized - gradient - corrected relativistic full - potential method . the electronic structure , magnetism and energetics of various spin configurations for lamno@xmath0 in the ideal cubic perovskite structure and the experimentally observed distorted orthorhombic structure are obtained . the excited state properties such as the optical , magneto - optical , x - ray photoemission ( xps ) , bremsstrahlung isochromat ( bis ) , x - ray absorption near edge structure ( xanes ) spectra are calculated and found to be in excellent agreement with available experimental results . consistent with earlier observations the insulating behavior can be obtained only when we take into account the structural distortions and the correct antiferromagnetic ordering in the calculations . the present results suggest that the correlation effect is not significant in lamno@xmath0 and the presence of ferromagnetic coupling within the @xmath1 plane as well as the antiferromagnetic coupling perpendicular to this plane can be explained through the itinerant band picture . as against earlier expectations , our calculations show that the mn 3@xmath2 @xmath3 as well as the @xmath4 electrons are present in the whole valence band region . in particular significantly large amounts of @xmath3 electrons are present in combination with the @xmath4 electrons at the top of the valence band against the common expectation of presence of only pure @xmath4 electrons . we have calculated the hyperfine field parameters for the a - type antiferromagnetic and the ferromagnetic phases of lamno@xmath0 and compared the findings with the available experimental results . the role of the orthorhombic distortion on electronic structure , magnetism and optical anisotropy are analyzed .
| 296
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1406.5011
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in this paper we study the higher regularity of the free boundary for the elliptic signorini problem . by using a partial hodograph - legendre transformation we show that the regular part of the free boundary is real analytic . the first complication in the study is the invertibility of the hodograph transform ( which is only @xmath0 ) which can be overcome by studying the precise asymptotic behavior of the solutions near regular free boundary points . the second and main complication in the study is that the equation satisfied by the legendre transform is degenerate . however , the equation has a subelliptic structure and can be viewed as a perturbation of the baouendi - grushin operator . by using the @xmath1 theory available for that operator , we can bootstrap the regularity of the legendre transform up to real analyticity , which implies the real analyticity of the free boundary .
| 154
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0903.3440
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2mass j03202839@xmath00446358ab is a recently identified , late - type m dwarf / t dwarf spectroscopic binary system for which both the radial velocity orbit for the primary and spectral types for both components have been determined . by combining these measurements with predictions from four different sets of evolutionary models , we determine a minimum age of 2.0@xmath10.3 gyr for this system , corresponding to minimum primary and secondary masses of 0.080 m@xmath2 and 0.053 m@xmath2 , respectively . we find broad agreement in the inferred age and mass constraints between the evolutionary models , including those that incorporate atmospheric condensate grain opacity ; however , we are not able to independently assess their accuracy . the inferred minimum age agrees with the kinematics and absence of magnetic activity in this system , but not the rapid rotation of its primary , further evidence of a breakdown in angular momentum evolution trends amongst the lowest luminosity stars . assuming a maximum age of 10 gyr , we constrain the orbital inclination of this system to @xmath3 . more precise constraints on the orbital inclination and/or component masses of 2mass 0320@xmath00446ab , through either measurement of the secondary radial velocity orbit ( optimally in the 1.21.3 @xmath4 band ) or detection of an eclipse ( only 0.3% probability based on geometric constraints ) , would yield a bounded age estimate for this system , and the opportunity to use it as an empirical test for brown dwarf evolutionary models at late ages .
| 253
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1511.06011
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we have developed a passive 350ghz ( 850@xmath0 m ) video - camera to demonstrate lumped element kinetic inductance detectors ( lekids ) designed originally for far - infrared astronomy as an option for general purpose terrestrial terahertz imaging applications . the camera currently operates at a quasi - video frame rate of 2hz with a noise equivalent temperature difference per frame of @xmath10.1k , which is close to the background limit . the 152 element superconducting lekid array is fabricated from a simple 40 nm aluminum film on a silicon dielectric substrate and is read out through a single microwave feedline with a cryogenic low noise amplifier and room temperature frequency domain multiplexing electronics .
| 116
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1612.02037
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the aim of this paper is to reconstruct and analyze the stability of some cosmological models against linear perturbations in @xmath0 gravity ( @xmath1 and @xmath2 represent the gauss - bonnet invariant and trace of the energy - momentum tensor , respectively ) . we formulate the field equations for both general as well as particular cases in the context of isotropic and homogeneous universe model . we reproduce the cosmic evolution corresponding to de sitter universe , power - law solutions and phantom / non - phantom eras in this theory using reconstruction technique . finally , we study stability analysis of de sitter as well as power - law solutions through linear perturbations . * keywords : * reconstruction ; stability analysis ; modified gravity . + * pacs : * 04.50.kd ; 98.80.-k .
| 137
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1011.0610
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in linear regression problems with related predictors , it is desirable to do variable selection and estimation by maintaining the hierarchical or structural relationships among predictors . in this paper we propose non - negative garrote methods that can naturally incorporate such relationships defined through effect heredity principles or marginality principles . we show that the methods are very easy to compute and enjoy nice theoretical properties . we also show that the methods can be easily extended to deal with more general regression problems such as generalized linear models . simulations and real examples are used to illustrate the merits of the proposed methods . , .
| 108
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1104.5201
|
we analyse the spatial distribution within host galaxies and chemical properties of the progenitors of long gamma ray bursts as a function of redshift . by using hydrodynamical cosmological simulations which include star formation , supernova feedback and chemical enrichment and based on the hypothesis of the collapsar model with low metallicity , we investigate the progenitors in the range @xmath0 . our results suggest that the sites of these phenomena tend to be located in the central regions of the hosts at high redshifts but move outwards for lower ones . we find that scenarios with low metallicity cut - offs best fit current observations . for these scenarios long gamma ray bursts tend to be [ fe / h ] poor and show a strong @xmath1-enhancement evolution towards lower values as redshift decreases . the variation of typical burst sites with redshift would imply that they might be tracing different part of galaxies at different redshifts . [ firstpage ] gamma - rays : bursts galaxies : abundances , evolution
| 172
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1112.4629
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in addition to well - motivated scenarios like supersymmetric particles , the so - called exotic matter ( quirky matter , hidden valley models , etc . ) can show up at the lhc and ilc , by exploring the spectroscopy of high mass levels and decay rates . in this paper we use qcd - inspired potential models , though without resorting to any particular one , to calculate level spacings of bound states and decay rates of the aforementioned exotic matter in order to design discovery strategies . we mainly focus on quirky matter , but our conclusions can be extended to other similar scenarios .
| 108
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astro-ph0302528
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we present 1.4 ghz vla observations of the variability of radio sources in the lockman hole region at the level of @xmath0jy on timescales of 17 months and 19 days . these data indicate that the areal density of highly variable sources at this level is @xmath1 arcmin@xmath2 . we set an upper limit of @xmath3 to the fraction of 50 to 100@xmath4jy sources that are highly variable ( @xmath5 ) . these results imply a lower limit to the beaming angle for grbs of 1@xmath6 , and give a lower limit of 200 arcmin@xmath7 to the area that can be safely searched for grb radio afterglows before confusion might become an issue .
| 114
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1610.03014
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in this paper , we develop an energy dissipative numerical scheme for gradient flows of planar curves , such as the curvature flow and the elastic flow . our study presents a general framework for solving such equations . to discretize time , we use a similar approach to the discrete partial derivative method , which is a structure - preserving method for the gradient flows of graphs . for the approximation of curves , we use b - spline curves . owing to the smoothness of b - spline functions , we can directly address higher order derivatives . in the last part of the paper , we consider some numerical examples of the elastic flow , which exhibit topology - changing solutions and more complicated evolution . videos illustrating our method are available on youtube .
| 138
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0910.5127
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in analogy with the recently proposed lepton mixing sum rules , we derive quark mixing sum rules for the case of hierarchical quark mass matrices with 1 - 3 texture zeros , in which the separate up and down type 1 - 3 mixing angles are approximately zero , and @xmath0 is generated from @xmath1 as a result of 1 - 2 up type quark mixing . using the sum rules , we discuss the phenomenological viability of such textures , including up to four texture zeros , and show how the right - angled unitarity triangle , i.e. , @xmath2 , can be accounted for by a remarkably simple scheme involving real mass matrices apart from a single element being purely imaginary . in the framework of grand unified theories , we show how the quark and lepton mixing sum rules may combine to yield an accurate prediction for the reactor angle .
| 154
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astro-ph0110337
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we utilize a sample of galaxy clusters at 0.35@xmath0@xmath1@xmath00.6 drawn from the las campanas distant cluster survey ( lcdcs ) to provide the first non - local constraint on the cluster - cluster spatial correlation function . the lcdcs catalog , which covers an effective area of 69 square degrees , contains over 1000 cluster candidates . estimates of the redshift and velocity dispersion exist for all candidates , which enables construction of statistically completed , volume - limited subsamples . in this analysis we measure the angular correlation function for four such subsamples at @xmath1@xmath20.5 . after correcting for contamination , we then derive spatial correlation lengths via limber inversion . we find that the resulting correlation lengths depend upon mass , as parameterized by the mean cluster separation , in a manner that is consistent with both local observations and cdm predictions for the clustering strength at @xmath1=0.5 .
| 151
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1605.02774
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quantum walks are recognizably useful for the development of new quantum algorithms , as well as for the investigation of several physical phenomena in quantum systems . actual implementations of quantum walks face technological difficulties similar to the ones for quantum computers , though . therefore , there is a strong motivation to develop new quantum - walk models which might be easier to implement . in this work , we present an extension of the staggered quantum walk model that is fitted for physical implementations in terms of time - independent hamiltonians . we demonstrate that this class of quantum walk includes the entire class of staggered quantum walk model , szegedy s model , and an important subset of the coined model .
| 125
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gr-qc0409109
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an exact but simple general relativistic model for the gravitational field of active galactic nuclei is constructed , based on the superposition in weyl coordinates of a black hole , a chazy - curzon disk and two rods , which represent matter jets . the influence of the rods on the matter properties of the disk and on its stability is examined . we find that in general they contribute to destabilize the disk . also the oscillation frequencies for perturbed circular geodesics on the disk are computed , and some geodesic orbits for the superposed metric are numerically calculated . pacs numbers : 04.20.jb , 04.40.-b , 98.58 fd , 98.62 mw
| 113
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1510.08679
|
motivated by a recent experiment [ nadj - perge et al . , science 346 , 602 ( 2014 ) ] providing evidence for majorana zero modes in iron chains on the superconducting pb surface , in the present work , we theoretically propose an all - optical scheme to detect majorana fermions , which is very different from the current tunneling measurement based on electrical means . the optical detection proposal consists of a quantum dot embedded in a nanomechanical resonator with optical pump - probe technology . with the optical means , the signal in the coherent optical spectrum presents a distinct signature for the existence of majorana fermions in the end of iron chains . further , the vibration of the nanomechanical resonator behaving as a phonon cavity will enhance the exciton resonance spectrum , which makes the majorana fermions more sensitive to be detectable . this optical scheme affords a potential supplement for detection of majorana fermions and supports to use majorana fermions in fe chains as qubits for potential applications in quantum computing devices .
| 180
|
cond-mat0602119
|
we consider the effect of thermal fluctuations on rotating spinor @xmath0 condensates in axially - symmetric vortex phases , when all the three hyperfine states are populated . we show that the relative phase among different components of the order parameter can fluctuate strongly due to the weakness of the interaction in the spin channel . these fluctuations can be significant even at low temperatures . fluctuations of relative phase lead to significant fluctuations of the local transverse magnetization of the condensate . we demonstrate that these fluctuations are much more pronounced for the antiferromagnetic state than for the ferromagnetic one .
| 102
|
astro-ph0210192
|
an analysis is made of the masses and spectral features for cosmic rays in the pev region , insofar as they have a bearing on the problem of the interaction of cosmic ray particles . in our single source model we identified two peaks seen in a summary of the world s data on primary spectra , and claimed that they are probably due to oxygen and iron nuclei from a local , recent supernova . in the present work we examine other possible mass assignments . we conclude that of the other possibilities only helium and oxygen ( instead of o and fe ) has much chance of success ; the original suggestion is still preferred , however . concerning our location with respect to the snr shell , the analysis suggests that we are close to it - probably just inside .
| 144
|
1405.2460
|
we introduce a method for performing a robust bayesian analysis of non - gaussianity present in pulsar timing data , simultaneously with the pulsar timing model , and additional stochastic parameters such as those describing red spin noise and dispersion measure variations . the parameters used to define the presence of non - gaussianity are zero for gaussian processes , giving a simple method of defining the strength of non - gaussian behaviour . we use simulations to show that assuming gaussian statistics when the noise in the data is drawn from a non - gaussian distribution can significantly increase the uncertainties associated with the pulsar timing model parameters . we then apply the method to the publicly available 15 year parkes pulsar timing array data release 1 dataset for the binary pulsar j0437@xmath04715 . in this analysis we present a significant detection of non - gaussianity in the uncorrelated non - thermal noise , but we find that it does not yet impact the timing model or stochastic parameter estimates significantly compared to analysis performed assuming gaussian statistics . the methods presented are , however , shown to be of immediate practical use for current european pulsar timing array ( epta ) and international pulsar timing array ( ipta ) datasets . [ firstpage ] methods : data analysis , pulsars : general , pulsars : individual
| 228
|
1011.3044
|
we directly construct model - independent mass profiles of galaxy clusters from combined weak - lensing distortion and magnification measurements within a bayesian statistical framework , which allows for a full parameter - space extraction of the underlying signal . this method applies to the full range of radius outside the einstein radius , and recovers the absolute mass normalization . we apply our method to deep subaru imaging of five high - mass ( @xmath0 ) clusters , a1689 , a1703 , a370 , cl0024 + 17 , and rxj1347 - 11 , to obtain accurate profiles to beyond the virial radius ( @xmath1 ) . for each cluster the lens distortion and magnification data are shown to be consistent with each other , and the total signal - to - noise ratio of the combined measurements ranges from 13 to 24 per cluster . we form a model - independent mass profile from stacking the clusters , which is detected at @xmath2 out to @xmath3 . the projected logarithmic slope @xmath4 steepens from @xmath5 at @xmath6 to @xmath7 at @xmath8 . we also derive for each cluster inner strong - lensing based mass profiles from deep advanced camera for surveys observations with the _ hubble space telescope _ , which we show overlap well with the outer subaru - based profiles and together are well described by a generalized form of the navarro - frenk - white profile , except for the ongoing merger rxj1347 - 11 , with modest variations in the central cusp slope ( @xmath9 ) . the improvement here from adding the magnification measurements is significant , @xmath10 in terms of cluster mass profile measurements , compared with the lensing distortion signal .
| 289
|
1004.3835
|
two gapped quantum ground states in the same phase are connected by an adiabatic evolution which gives rise to a local unitary transformation that maps between the states . on the other hand , gapped ground states remain within the same phase under local unitary transformations . therefore , local unitary transformations define an equivalence relation and the equivalence classes are the universality classes that define the different phases for gapped quantum systems . since local unitary transformations can remove local entanglement , the above equivalence / universality classes correspond to pattern of long range entanglement , which is the essence of topological order . the local unitary transformation also allows us to define a wave function renormalization scheme , under which a wave function can flow to a simpler one within the same equivalence / universality class . using such a setup , we find conditions on the possible fixed - point wave functions where the local unitary transformations have _ finite _ dimensions . the solutions of the conditions allow us to classify this type of topological orders , which generalize the string - net classification of topological orders . we also describe an algorithm of wave function renormalization induced by local unitary transformations . the algorithm allows us to calculate the flow of tensor - product wave functions which are not at the fixed points . this will allow us to calculate topological orders as well as symmetry breaking orders in a generic tensor - product state .
| 251
|
hep-ph9809268
|
relativistic heavy ion collisions offer the possibility to produce exotic metastable states of nuclear matter containing ( roughly ) equal number of strangeness compared to the content in baryon number . the reasoning of both their stability and existence , the possible distillation of strangeness necessary for their formation and the chances for their detection are reviewed . in the later respect emphasize is put on the properties of small lumps of strange quark matter with respect to their stability against strong or weak hadronic decays . in addition , implications in astrophysics like the properties of neutron stars and the issue of baryonic dark matter will be discussed .
| 110
|
1403.4087
|
although type ia supernovae ( sne ia ) are a major tool in cosmology and play a key role in the chemical evolution of galaxies , the nature of their progenitor systems ( apart from the fact that they must content at least one white dwarf , that explodes ) remains largely unknown . in the last decade , considerable efforts have been made , both observationally and theoretically , to solve this problem . observations have , however , revealed a previously ususpected variety of events , ranging from very underluminous outbursts to clearly overluminous ones , and spanning a range well outside the peak luminosity decline rate of the light curve relationship , used to make calibrated candles of the sne ia . on the theoretical side , new explosion scenarios , such as violent mergings of pairs of white dwarfs , have been explored . we review those recent developments , emphasizing the new observational findings , but also trying to tie them to the different scenarios and explosion mechanisms proposed thus far .
| 177
|
1210.2292
|
in a recent paper @xcite miro - roig , mezzetti and ottaviani highlight the link between rational varieties satisfying a laplace equation and artinian ideals failing the weak lefschetz property . continuing their work we extend this link to the more general situation of artinian ideals failing the strong lefschetz property . we characterize the failure of the slp ( which includes wlp ) by the existence of special singular hypersurfaces ( cones for wlp ) . this characterization allows us to solve three problems posed in @xcite and to give new examples of ideals failing the slp . finally , line arrangements are related to artinian ideals and the unstability of the associated derivation bundle is linked to the failure of the slp . moreover we reformulate the so - called terao s conjecture for free line arrangements in terms of artinian ideals failing the slp .
| 148
|
astro-ph0006003
|
we present a new sample of distant ultraluminous infrared galaxies . the sample was selected from a positional cross correlation of the @xmath0 faint source catalog with the first database . objects from this set were selected for spectroscopy by virtue of following the well - known star - forming galaxy correlation between 1.4 ghz and 60 @xmath1 m flux , and by being optically faint on the poss . optical identification and spectroscopy were obtained for 108 targets at the lick observatory 3 m telescope . most objects show spectra typical of starburst galaxies , and do not show the high ionization lines of active galactic nuclei . the redshift distribution covers @xmath2 , with 13 objects at @xmath3 and an average redshift of @xmath4 . @xmath5-band images were obtained at the irtf , lick , and keck observatories in sub - arcsec seeing of all optically identified targets . about 2/3 of the objects appear to be interacting galaxies , while the other 1/3 appear to be normal . nearly all the identified objects have far - ir luminosities greater than @xmath6 , and @xmath725 % have @xmath8 .
| 191
|
gr-qc9710049
|
we describe a class of impulsive gravitational waves which propagate either in a de sitter or an anti - de sitter background . they are conformal to impulsive waves of kundt s class . in a background with positive cosmological constant they are spherical ( but non - expanding ) waves generated by pairs of particles with arbitrary multipole structure propagating in opposite directions . when the cosmological constant is negative , they are hyperboloidal waves generated by a null particle of the same type . in this case , they are included in the impulsive limit of a class of solutions described by siklos that are conformal to _ pp_-waves . pacs class 04.20.jb , 04.30.nk running title : _ impulsive waves in ( anti-)de sitter space - time _
| 131
|
1401.3352
|
@xcite [ k13 ] introduced a new methodology for determining peak - brightness absolute magnitudes of type ia supernovae from multi - band light curves . we examine the relation between their parameterization of light curves and hubble residuals , based on photometry synthesized from the nearby supernova factory spectrophotometric time series , with global host - galaxy properties . the k13 hubble residual step with host mass is @xmath0 mag for a supernova subsample with data coverage corresponding to the k13 training ; at @xmath1 , the step is not significant and lower than previous measurements . relaxing the data coverage requirement the hubble residual step with host mass is @xmath2 mag for the larger sample ; a calculation using the modes of the distributions , less sensitive to outliers , yields a step of 0.019 mag . the analysis of this article uses k13 inferred luminosities , as distinguished from previous works that use magnitude corrections as a function of salt2 color and stretch parameters : steps at @xmath3 significance are found in salt2 hubble residuals in samples split by the values of their k13 @xmath4 and @xmath5 light - curve parameters . @xmath4 affects the light - curve width and color around peak ( similar to the @xmath6 and stretch parameters ) , and @xmath5 affects colors , the near - uv light - curve width , and the light - curve decline 20 to 30 days after peak brightness . the novel light - curve analysis , increased parameter set , and magnitude corrections of k13 may be capturing features of sn ia diversity arising from progenitor stellar evolution .
| 274
|
1012.0028
|
_ swift _ observed an outburst from the supergiant fast x ray transient ( sfxt ) ax j1841.0@xmath00536 on 2010 june 5 , and followed it with xrt for 11 days . the x ray light curve shows an initial flare followed by a decay and subsequent increase , as often seen in other sfxts , and a dynamical range of @xmath1 . our observations allow us to analyse the simultaneous broad - band ( 0.3100kev ) spectrum of this source , for the first time down to 0.3kev , which can be fitted well with models usually adopted to describe the emission from accreting neutron stars in high - mass x ray binaries , and is characterized by a high absorption ( @xmath2 @xmath3 ) , a flat power law ( @xmath4 ) , and a high energy cutoff . all of these properties resemble those of the prototype of the class , igr j17544@xmath02619 , which underwent an outburst on 2010 march 4 , whose observations we also discuss . we show how well ax j1841.0@xmath00536 fits in the sfxt class , based on its observed properties during the 2010 outburst , its large dynamical range in x ray luminosity , the similarity of the light curve ( length and shape ) to those of the other sfxts observed by _ swift _ , and the x ray broad - band spectral properties . [ firstpage ] x - rays : binaries - x - rays : individual : ax j1841.0@xmath00536 - x - rays : individual : igr j17544@xmath02619 facility : _ swift _
| 267
|
1405.5349
|
in many image and signal processing applications , as interferometric synthetic aperture radar ( sar ) or color image restoration in hsv or lch spaces the data has its range on the one - dimensional sphere @xmath0 . although the minimization of total variation ( tv ) regularized functionals is among the most popular methods for edge - preserving image restoration such methods were only very recently applied to cyclic structures . however , as for euclidean data , tv regularized variational methods suffer from the so called staircasing effect . this effect can be avoided by involving higher order derivatives into the functional . this is the first paper which uses higher order differences of cyclic data in regularization terms of energy functionals for image restoration . we introduce absolute higher order differences for @xmath0-valued data in a sound way which is independent of the chosen representation system on the circle . our absolute cyclic first order difference is just the geodesic distance between points . similar to the geodesic distances the absolute cyclic second order differences have only values in @xmath1 $ ] . we update the cyclic variational tv approach by our new cyclic second order differences . to minimize the corresponding functional we apply a cyclic proximal point method which was recently successfully proposed for hadamard manifolds . choosing appropriate cycles this algorithm can be implemented in an efficient way . the main steps require the evaluation of proximal mappings of our cyclic differences for which we provide analytical expressions . under certain conditions we prove the convergence of our algorithm . various numerical examples with artificial as well as real - world data demonstrate the advantageous performance of our algorithm .
| 286
|
1503.01566
|
in this paper we demonstrate the rate gains achieved by two - tier heterogeneous cellular networks ( hetnets ) with varying degrees of coordination between macrocell and microcell base stations ( bss ) . we show that without the presence of coordination , network densification does not provide any gain in the sum rate and rapidly decreases the mean per - user signal - to - interference - plus - noise - ratio ( sinr ) . our results show that coordination reduces the rate of sinr decay with increasing numbers of microcell bss in the system . validity of the analytically approximated mean per - user sinr over a wide range of signal - to - noise - ratio ( snr ) is demonstrated via comparison with the simulated results .
| 132
|
1208.3384
|
let @xmath0 be a set of @xmath1 points in @xmath2 . we present a linear - size data structure for answering range queries on @xmath0 with constant - complexity semialgebraic sets as ranges , in time close to @xmath3 . it essentially matches the performance of similar structures for simplex range searching , and , for @xmath4 , significantly improves earlier solutions by the first two authors obtained in 1994 . this almost settles a long - standing open problem in range searching . the data structure is based on the polynomial - partitioning technique of guth and katz [ arxiv:1011.4105 ] , which shows that for a parameter @xmath5 , @xmath6 , there exists a @xmath7-variate polynomial @xmath8 of degree @xmath9 such that each connected component of @xmath10 contains at most @xmath11 points of @xmath0 , where @xmath12 is the zero set of @xmath8 . we present an efficient randomized algorithm for computing such a polynomial partition , which is of independent interest and is likely to have additional applications .
| 172
|
astro-ph0602574
|
we propose a method to identify the companion stars of type ia supernovae ( sne ia ) in young supernova remnants ( snrs ) by recognizing distinct features of absorption lines due to fe i appearing in the spectrum . if a sufficient amount of fe i remains in the ejecta , fe i atoms moving toward us absorb photons by transitions from the ground state to imprint broad absorption lines exclusively with the blue - shifted components in the spectrum of the companion star . to investigate the time evolution of column depth of fe i in the ejecta , we have performed hydrodynamical calculations for snrs expanding into the uniform ambient media , taking into account collisional ionizations , excitations , and photo - ionizations of heavy elements . as a result , it is found that the companion star in tycho s snr will exhibit observable features in absorption lines due to fe i at @xmath0 nm and 385.9911 nm if a carbon deflagration sn model @xcite is taken . however , these features may disappear by taking another model that emits a few times more intense ionizing photons from the shocked outer layers . to further explore the ionization states in the freely expanding ejecta , we need a reliable model to describe the structure of the outer layers .
| 224
|
0710.2679
|
group field theories , a generalization of matrix models for 2d gravity , represent a 2nd quantization of both loop quantum gravity and simplicial quantum gravity . in this paper , we construct a new class of group field theory models , for any choice of spacetime dimension and signature , whose feynman amplitudes are given by path integrals for clearly identified discrete gravity actions , in 1st order variables . in the 3-dimensional case , the corresponding discrete action is that of 1st order regge calculus for gravity ( generalized to include higher order corrections ) , while in higher dimensions , they correspond to a discrete bf theory ( again , generalized to higher order ) with an imposed orientation restriction on hinge volumes , similar to that characterizing discrete gravity . the new models shed also light on the large distance or semi - classical approximation of spin foam models . this new class of group field theories may represent a concrete unifying framework for loop quantum gravity and simplicial quantum gravity approaches .
| 177
|
1305.3490
|
we analyze the so - called shortest queue first ( sqf ) queueing discipline whereby a unique server addresses queues in parallel by serving at any time that queue with the smallest workload . considering a stationary system composed of two parallel queues and assuming poisson arrivals and general service time distributions , we first establish the functional equations satisfied by the laplace transforms of the workloads in each queue . we further specialize these equations to the so - called `` symmetric case '' , with same arrival rates and identical exponential service time distributions at each queue ; we then obtain a functional equation @xmath0 for unknown function @xmath1 , where given functions @xmath2 , @xmath3 and @xmath4 are related to one branch of a cubic polynomial equation . we study the analyticity domain of function @xmath1 and express it by a series expansion involving all iterates of function @xmath4 . this allows us to determine empty queue probabilities along with the tail of the workload distribution in each queue . this tail appears to be identical to that of the head - of - line preemptive priority system , which is the key feature desired for the sqf discipline .
| 203
|
1304.1918
|
photoproduction of @xmath0 and @xmath1 pairs from nuclei has been measured over a wide mass range ( @xmath2h , @xmath3li , @xmath4c , @xmath5ca , and @xmath6pb ) for photon energies from threshold to 600 mev . the experiments were performed at the mami accelerator in mainz , using the glasgow photon tagging spectrometer and a 4@xmath7 electromagnetic calorimeter consisting of the crystal ball and taps detectors . a shift of the pion - pion invariant mass spectra for heavy nuclei to small invariant masses has been observed for @xmath8 pairs but also for the mixed - charge pairs . the precise results allow for the first time a model - independent analysis of the influence of pion final - state interactions . the corresponding effects are found to be large and must be carefully considered in the search for possible in - medium modifications of the @xmath9-meson . results from a transport model calculation reproduce the shape of the invariant - mass distributions for the mixed - charge pairs better than for the neutral pairs , but also for the latter differences between model results and experiment are not large , leaving not much room for @xmath9-in - medium modification . , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , ,
| 264
|
hep-ph9509377
|
the solution of qcd equations for generating functions of multiplicity distributions reveals new peculiar features of cumulant moments oscillating as functions of their rank . this prediction is supported by experimental data on @xmath0 collisions . evolution of the moments at smaller phase space bins leads to intermittency and fractality . the experimentally defined truncated generating functions possess zeros in the complex plane of an auxiliary variable recalling lee - yang zeros in statistical mechanics . * novel features of multiplicity distributions in qcd and experiment * i.m.dremin lebedev physical institute , moscow 117924 , russia contents + \1 . introduction + 2 . _ oscillations _ of cumulants of multiplicity distributions in qcd + 3 . _ evolution _ of distributions with decreasing phase space volume + intermittency and fractality + 4 . _ zeros _ of truncated generating functions + 5 . discussion and conclusions +
| 148
|
1507.06512
|
we have identified outflows and bubbles in the taurus molecular cloud based on the @xmath0 deg@xmath1 five college radio astronomy observatory @xmath2co(1 - 0 ) and @xmath3co(1 - 0 ) maps and the spitzer young stellar object catalogs . in the main 44 deg@xmath1 area of taurus we found 55 outflows , of which 31 were previously unknown . we also found 37 bubbles in the entire 100 deg@xmath1 area of taurus , all of which had not been found before . the total kinetic energy of the identified outflows is estimated to be @xmath4 erg , which is * 1% * of the cloud turbulent energy . the total kinetic energy of the detected bubbles is estimated to be @xmath5 erg , which is 29% of the turbulent energy of taurus . the energy injection rate from outflows is @xmath6 , * 0.4 - 2 times * the dissipation rate of the cloud turbulence . the energy injection rate from bubbles is @xmath7 erg s@xmath8 , * 2 - 10 times * the turbulent dissipation rate of the cloud . the gravitational binding energy of the cloud is @xmath9 * erg * , * 385 * and 16 times the energy of outflows and bubbles , respectively . we conclude that neither outflows nor bubbles can * provide enough energy to balance the overall gravitational binding energy and the turbulent energy of taurus . however , * in the current epoch , stellar feedback is sufficient to maintain the observed turbulence in taurus . = 5000 = 1000
| 259
|
cond-mat0210701
|
the angular and temperature dependence of the upper critical field @xmath0 in mgb@xmath1 was determined from torque magnetometry measurements on single crystals . the @xmath0 anisotropy @xmath2 was found to decrease with increasing temperature , in disagreement with the anisotropic ginzburg - landau theory , which predicts that the @xmath2 is temperature independent . this behaviour can be explained by the two band nature of superconductivity in mgb@xmath1 . an analysis of measurements of the reversible torque in the mixed state yields a field dependent effective anisotropy @xmath3 , which can be at least partially explained by different anisotropies of the penetration depth and the upper critical field . it is shown that a peak effect in fields of about @xmath4 is a manifestation of an _ order - disorder _ phase transition of vortex matter . the @xmath5-@xmath6 phase diagram of mgb@xmath1 for @xmath7 correlates with the intermediate strength of thermal fluctuations in mgb@xmath1 , as compared to those in high and low @xmath8 superconductors .
| 167
|
0810.4525
|
the black hole information paradox is one of the most important issues in theoretical physics . we review some recent progress using string theory in understanding the nature of black hole microstates . for all cases where these microstates have been constructed , one finds that they are horizon sized ` fuzzballs ' . most computations are for extremal states , but recently one has been able to study a special family of non - extremal microstates , and see ` information carrying radiation ' emerge from these gravity solutions . we discuss how the fuzzball picture can resolve the information paradox . we use the nature of fuzzball states to make some conjectures on the dynamical aspects of black holes , observing that the large phase space of fuzzball solutions can make the black hole more ` quantum ' than assumed in traditional treatments . _ black holes , string theory _ :
| 154
|
quant-ph0602083
|
a system of cascaded qubits interacting via the oneway exchange of photons is studied . while for general operating conditions the system evolves to a superposition of bell states ( a dark state ) in the long - time limit , under a particular _ resonance _ condition no steady state is reached within a finite time . we analyze the conditional quantum evolution ( quantum trajectories ) to characterize the asymptotic behavior under this resonance condition . a distinct bimodality is observed : for perfect qubit coupling , the system either evolves to a maximally entangled bell state without emitting photons ( the dark state ) , or executes a sustained entangled - state cycle random switching between a pair of bell states while emitting a continuous photon stream ; for imperfect coupling , two entangled - state cycles coexist , between which a random selection is made from one quantum trajectory to another .
| 156
|
1509.03267
|
we construct a theory in which the gravitational interaction is described only by torsion , but that generalizes the teleparallel theory still keeping the invariance of local lorentz transformations in one particular case . we show that our theory falls , to a certain limit of a real parameter , in the @xmath0 gravity or , to another limit of the same real parameter , in a modified @xmath1 gravity , interpolating between these two theories and still can fall on several other theories . we explicitly show the equivalence with @xmath0 gravity for cases of friedmann - lemaitre - robertson - walker flat metric for diagonal tetrads , and a metric with spherical symmetry for diagonal and non - diagonal tetrads . we do still four applications , one in the reconstruction of the de sitter universe cosmological model , for obtaining a static spherically symmetric solution type - de sitter for a perfect fluid , for evolution of the state parameter @xmath2 and for the thermodynamics to the apparent horizon .
| 173
|
nucl-th0607039
|
the nucleus of @xmath0pb a system that is 18 order of magnitudes smaller and 55 orders of magnitude lighter than a neutron star may be used as a miniature surrogate to establish important correlations between its neutron skin and several neutron - star properties . indeed , a nearly model - independent correlation develops between the neutron skin of @xmath1pb and the liquid - to - solid transition density in a neutron star . further , we illustrate how a measurement of the neutron skin in @xmath0pb may be used to place important constraints on the cooling mechanism operating in neutron stars and may help elucidate the existence of quarks stars .
| 112
|
1701.00977
|
based on the observation that the correlation between observed traffic at two measurement points or traffic stations may be time - varying , attributable to the time - varying speed which subsequently causes variations in the time required to travel between the two points , in this paper , we develop a modified space - time autoregressive integrated moving average ( starima ) model with time - varying lags for short - term traffic flow prediction . particularly , the temporal lags in the modified starima change with the time - varying speed at different time of the day or equivalently change with the ( time - varying ) time required to travel between two measurement points . firstly , a technique is developed to evaluate the temporal lag in the starima model , where the temporal lag is formulated as a function of the spatial lag ( spatial distance ) and the average speed . secondly , an unsupervised classification algorithm based on isodata algorithm is designed to classify different time periods of the day according to the variation of the speed . the classification helps to determine the appropriate time lag to use in the starima model . finally , a starima - based model with time - varying lags is developed for short - term traffic prediction . experimental results using real traffic data show that the developed starima - based model with time - varying lags has superior accuracy compared with its counterpart developed using the traditional cross - correlation function and without employing time - varying lags .
| 263
|
0901.0963
|
a novel type of correlation involving particle - antiparticle pairs was found out in the 1990 s . currently known as squeezed or back - to - back correlations ( bbc ) , they should be present if the hadronic masses are modified in the hot and dense medium formed in high energy heavy ion collisions . although well - established theoretically , such hadronic correlations have not yet been observed experimentally . in this phenomenological study we suggest a promising way to search for the bbc signal , by looking into the squeezed correlation function of @xmath0 and @xmath1 pairs at rhic energies , as function of the pair average momentum , @xmath2 . the effects of in - medium mass - shift on the identical particle correlations ( hanbury - brown & twiss effect ) are also discussed .
| 141
|
1105.0429
|
we use restframe near- and mid - ir data of an isotropically selected sample of quasars and radio galaxies at @xmath0 , which have been published previously , to study the wavelength - dependent anisotropy of the ir emission . for that we build average seds of the quasar subsample (= type 1 agn ) and radio galaxies (= type 2 agn ) from @xmath1 and plot the ratio of both average samples . from 2 to 8@xmath2 restframe wavelength the ratio gradually decreases from 20 to 2 with values around 3 in the 10@xmath2 silicate feature . longward of 12@xmath2 the ratio decreases further and shows some high degree of isotropy at 15@xmath2 ( ratio @xmath31.4 ) . the results are consistent with upper limits derived from the x - ray / mid - ir correlation of local seyfert galaxies . we find that the anisotropy in our high - luminosity radio - loud sample is smaller than in radio - quiet lower - luminosity agn which may be interpreted in the framework of a receding torus model with luminosity - dependent obscuration properties . it is also shown that the relatively small degree of anisotropy is consistent with clumpy torus models .
| 204
|
cond-mat9804217
|
we compute phase diagrams for @xmath0 starblock copolymers in the strong - segregation regime as a function of volume fraction @xmath1 , including bicontinuous phases related to minimal surfaces ( g , d , and p surfaces ) as candidate structures . we present the details of a general method to compute free energies in the strong segregation limit , and demonstrate that the gyroid g phase is the most nearly stable among the bicontinuous phases considered . we explore some effects of conformational asymmetry on the topology of the phase diagram . # 1*#1 * # 1 10truept * [ fig # 1 here ] * 2
| 108
|
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