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when the lyapunov exponent $ \ lambda _ l $ in a quantum chaotic system saturates the bound $ \ lambda _ l \ leqslant 2 \ pi k _ bt $, it is proposed that this system has a holographic dual described by a gravity theory. in particular, the butterfly effect as a prominent phenomenon of chaos can ubiquitously exist in a black hole system characterized by a shockwave solution near the horizon. in this paper we propose that the butterfly velocity can be used to diagnose quantum phase transition ( qpt ) in holographic theories. we provide evidences for this proposal with an anisotropic holographic model exhibiting metal - insulator transitions ( mit ), in which the derivatives of the butterfly velocity with respect to system parameters characterizes quantum critical points ( qcp ) with local extremes in zero temperature limit. we also point out that this proposal can be tested by experiments in the light of recent progress on the measurement of out - of - time - order correlation function ( otoc ).
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arxiv:1610.02669
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in two - mode interferometry, for a given total photon number $ n $, entangled fock state superpositions of the form $ ( | n - m \ rangle _ a | m \ rangle _ b + e ^ { i ( n - 2m ) \ phi } | m \ rangle _ a | n - m \ rangle _ b ) / \ sqrt { 2 } $ have been considered for phase estimation. indeed all such states are maximally mode - entangled and violate a clauser - horne - shimony - holt ( chsh ) inequality. however, they differ in their optimal phase estimation capabilities as given by their quantum fisher informations. the quantum fisher information is the largest for the $ n00n $ state $ ( | n \ rangle _ a | 0 \ rangle _ b + e ^ { i n \ phi } | 0 \ rangle _ a | n \ rangle _ b ) / \ sqrt { 2 } $ and decreases for the other states with decreasing photon number difference between the two modes. we ask the question whether for any particular clauser - horne ( ch ) ( or chsh ) inequality, the maximal values of the ch ( or the chsh ) functional for the states of the above type follow the same trend as their quantum fisher informations, while also violating the classical bound whenever the states are capable of sub - shot - noise phase estimation, so that the violation can be used to quantify sub - shot - noise sensitivity. we explore ch and chsh inequalities in a homodyne setup. our results show that the amount of violation in those nonlocality tests may not be used to quantify sub - shot - noise sensitivity of the above states.
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arxiv:1310.1410
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universal relations that hold for any state provide powerful constraints on systems consisting of fermions with two spin states interacting with a large scattering length. in radio - frequency ( rf ) spectroscopy, the mean shift in the rf frequency and the large frequency tail of the rf transition rate are proportional to the contact, which measures the density of pairs with small separations. we show that these universal relations can be derived and extended by using the short - time operator product expansion of quantum field theory. this is a general method for identifying aspects of many - body physics that are controlled by few - body physics.
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arxiv:1001.4518
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for reliability, it is important that the predictions made by machine learning methods are interpretable by human. in general, deep neural networks ( dnns ) can provide accurate predictions, although it is difficult to interpret why such predictions are obtained by dnns. on the other hand, interpretation of linear models is easy, although their predictive performance would be low since real - world data is often intrinsically non - linear. to combine both the benefits of the high predictive performance of dnns and high interpretability of linear models into a single model, we propose neural generators of sparse local linear models ( ngslls ). the sparse local linear models have high flexibility as they can approximate non - linear functions. the ngsll generates sparse linear weights for each sample using dnns that take original representations of each sample ( e. g., word sequence ) and their simplified representations ( e. g., bag - of - words ) as input. by extracting features from the original representations, the weights can contain rich information to achieve high predictive performance. additionally, the prediction is interpretable because it is obtained by the inner product between the simplified representations and the sparse weights, where only a small number of weights are selected by our gate module in the ngsll. in experiments with real - world datasets, we demonstrate the effectiveness of the ngsll quantitatively and qualitatively by evaluating prediction performance and visualizing generated weights on image and text classification tasks.
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arxiv:2003.06441
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in this note, we establish optimal lower and upper gaussian bounds for the density of the solution to a class of stochastic integral equations driven by an additive spatially homogeneous gaussian random field. the proof is based on the techniques of the malliavin calculus and a density formula obtained by nourdin and viens. then, the main result is applied to the mild solution of a general class of spdes driven by a gaussian noise which is white in time and has a spatially homogeneous correlation. in particular, this covers the case of the stochastic heat and wave equations in $ \ mathbb { r } ^ d $ with $ d \ geq 1 $ and $ d \ leq 3 $, respectively. the upper and lower gaussian bounds have the same form and are given in terms of the variance of the stochastic integral term in the mild form of the equation.
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arxiv:0912.3707
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n / d ) ^ { 3 / 2 } ), & \ text { for ~ } d > n ^ { 1 / 3 } ~. \ end { cases } \ ] we also extend our algorithms to provide improved $ ( \ beta, \ epsilon ) $ hopsets for $ n $ - vertex weighted directed graphs.
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arxiv:2111.13240
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propose - test - release ( ptr ) is a differential privacy framework that works with local sensitivity of functions, instead of their global sensitivity. this framework is typically used for releasing robust statistics such as median or trimmed mean in a differentially private manner. while ptr is a common framework introduced over a decade ago, using it in applications such as robust sgd where we need many adaptive robust queries is challenging. this is mainly due to the lack of renyi differential privacy ( rdp ) analysis, an essential ingredient underlying the moments accountant approach for differentially private deep learning. in this work, we generalize the standard ptr and derive the first rdp bound for it when the target function has bounded global sensitivity. we show that our rdp bound for ptr yields tighter dp guarantees than the directly analyzed $ ( \ eps, \ delta ) $ - dp. we also derive the algorithm - specific privacy amplification bound of ptr under subsampling. we show that our bound is much tighter than the general upper bound and close to the lower bound. our rdp bounds enable tighter privacy loss calculation for the composition of many adaptive runs of ptr. as an application of our analysis, we show that ptr and our theoretical results can be used to design differentially private variants for byzantine robust training algorithms that use robust statistics for gradients aggregation. we conduct experiments on the settings of label, feature, and gradient corruption across different datasets and architectures. we show that ptr - based private and robust training algorithm significantly improves the utility compared with the baseline.
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arxiv:2209.07716
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we study arithmetic properties of equivariant birational types introduced by kontsevich, pestun, and the second author.
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arxiv:2012.04146
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the space of global sections of the chiral de rham complex on any closed complex curve with genus $ g \ ge2 $ is calculated.
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arxiv:2501.08743
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we address one of the important problems in big data, namely how to combine estimators from different subsamples by robust fusion procedures, when we are unable to deal with the whole sample.
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arxiv:1705.10157
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optical ( or robinson ) structures are one generalisation of four - dimensional shearfree congruences of null geodesics to higher dimensions. they are lorentzian analogues of complex and cr structures. in this context, we extend the goldberg - sachs theorem to five dimensions. to be precise, we find a new algebraic condition on the weyl tensor, which generalises the petrov type ii condition, in the sense that it ensures the existence of such congruences on a five - dimensional spacetime, vacuum or under weaker assumptions on the ricci tensor. this results in a significant simplification of the field equations. we discuss possible degenerate cases, including a five - dimensional generalisation of the petrov type d condition. we also show that the vacuum black ring solution is endowed with optical structures, yet fails to be algebraically special with respect to them. we finally explain the generalisation of these ideas to higher dimensions, which has been checked in six and seven dimensions.
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arxiv:1011.6168
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how t tauri stars remain slowly rotating while still accreting material is a long - standing puzzle. current models suggest that these stars may lose angular momentum through magnetospheric ejections of disk material ( mes ) and accretion - powered stellar winds ( apsws ). the individual contribution of each mechanism to the stellar spin evolution, however, is unclear. we explore how these two scenarios could be distinguished by applying stellar spin models to near - term observations. we produce synthetic stellar populations of accreting class ii stars with spreads in the parameters governing the spin - down processes and find that an apsw strongly affects the ratio of the disk truncation radius to the corotation radius, $ \ mathcal { r } = r _ \ mathrm { t } / r _ \ mathrm { co } $. the me and apsw scenarios are distinguished to high confidence when at least $ n _ \ mathrm { crit } \ gtrsim 250 $ stars have values measured for $ \ mathcal { r } $. newly developed lightcurve analysis methods enable measuring $ \ mathcal { r } $ for enough stars to distinguish the spin - down scenarios in the course of upcoming observing campaigns.
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arxiv:2504.03374
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in this paper, we deduce the expression of the gravito - acoustic force between two oscillating bubbles using the hypothesis that this type of force is a force of scattering - absorption of the energy of excitatory waves. the expression of the gravito - acoustic force at resonance highlights the dependence of this force on the product of the virtual masses of the two bubbles and on an acoustic gravitational constant. the acoustic gravitational constant depends on the absorption damping coefficient. we may say also that the expression of the acoustic gravitational constant is analogous to the expression of the gravitational constant in the electromagnetic world, that one obtained in the einstein - sciama model and the dirac - eddington large numbers hypothesis. the results obtained for this type of phenomenon in the acoustic world support the similarity between the acoustic world and the electromagnetic world.
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arxiv:2206.00435
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the profile of the silicate 10 $ \ mu $ m ir band contains important information about the evolutional stage of dust in circumstellar environments and the possible ongoing process of planetesimal formation. in order to extract this information, the observed band profiles are compared with calculated or laboratory - measured absorption cross sections of amorphous and crystalline grains with different sizes and compositions. we present in this study the first laboratory measurements of the 10 $ \ mu $ m band profiles of nonembedded, i. e. free - flying, particles of amorphous and crystalline mg $ _ 2 $ sio $ _ 4 $ ( with two different particle shapes ), amorphous and crystalline mgsio $ _ 3 $, and crystalline olivine. we compare the spectra with those measured on embedded grains and discuss the potential of the new experimental method for comparison with observed spectra, as well as for future studies of agglomeration and surface manipulation of the grains.
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arxiv:astro-ph/0609231
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the widespread application of llms across various tasks and fields has necessitated the alignment of these models with human values and preferences. given various approaches of human value alignment, there is an urgent need to understand the scope and nature of human values injected into these llms before their deployment and adoption. we propose univar, a high - dimensional neural representation of symbolic human value distributions in llms, orthogonal to model architecture and training data. this is a continuous and scalable representation, self - supervised from the value - relevant output of 8 llms and evaluated on 15 open - source and commercial llms. through univar, we visualize and explore how llms prioritize different values in 25 languages and cultures, shedding light on complex interplay between human values and language modeling.
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arxiv:2404.07900
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we show $ \ ell ^ p \ big ( \ mathbb z ^ d \ big ) $ boundedness, for $ p \ in ( 1, \ infty ) $, of discrete singular integrals of radon type with the aid of appropriate square function estimates, which can be thought as a discrete counterpart of the littlewood - - paley theory. it is a very powerful approach which allows us to proceed as in the continuous case.
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arxiv:1512.07524
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in these lectures we first briefly review the main observational facts which imply that most part of matter in the universe is not visible and some recent intriguing experimental data which would point to a significant contribution to omega due to a cosmological constant. we subsequently discuss some particle candidates for dark matter, with particular emphasis for the neutralino. we present the main properties of this particle, also in the light of the most recent experimental results in direct search for relic particles ; furthermore, we discuss the perspectives for their indirect searches.
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arxiv:hep-ph/9904469
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we demonstrate experimentally the creation and measurement of an entangled state between a microscopic two level system and a macroscopic superconducting resonator where their indirect interaction is mediated by an artificial atom, a superconducting persistent current qubit ( pcqb ). we show that the microscopic two level system, formed by a defect in an oxide layer, exhibits an order of magnitude longer dephasing time than the pcqb, while the dephasing time of the entangled states between the microscopic two level system and macroscopic superconducting resonator is significantly longer than the dephasing time in the persistent current qubits. this demonstrates the possibility that a qubit of moderate coherence properties can be used in practice to address low decoherence quantum memories by connecting them to macroscopic circuit qed quantum buses, leading future important implications for quantum information processing tasks.
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arxiv:1008.4212
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we recently discovered that ngc 3201 has characteristics that set it outside the current twofold classification scheme for galactic globular clusters ( gcs ). most gcs are mono - metallic and show light - element abundance variations ( e. g., na - o and c - n anti - correlations ) ; but a minority of clusters also present variations in fe correlating with s - process element and c + n + o abundances, and they possess multiple c - n sequences. these anomalous gcs also have a broad sub - giant branch ( sgb ) and follow the same mass - size relation as dwarf galaxies possibly evolving into gcs. we now revealed that ngc 3201 belongs to neither group. it has multiple c - n sequences, but no broad sgb, no strong evidence of a fe - spread, and it does not follow the mass - size relation.
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arxiv:1909.02567
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polycrystalline cuo samples with co doping were prepared by solid state method with flowing oxygen condition and examined their structural and multiferroic properties. structural studies have confirmed single phase monoclinic crystal structure of all samples, however, in co doped samples a decrease in volume with an increase in monoclinic distortion is found. for pristine sample, temperature dependent magnetization has confirmed two antiferromagnetic ( afm ) transitions at 213 k and 230 k and frequency independent dielectric peaks at these afm transitions suggesting the ferroelectric nature. magnetization of the co doped samples has showed a marginal increase in ordering temperature of the high - temperature afm transition and decrease in low temperature afm ordering temperature. further, doped samples have shown giant dielectric constant with no signature of ferroelectricity. the x - ray photoelectric spectroscopy study has revealed multiple valance states for both co and cu in the doped samples that simultaneously explain the giant dielectric constant and suppression of ferroelectric order.
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arxiv:1608.04486
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we study surface plasmons localized on interfaces between topologically trivial and topologically non - trivial time reversal invariant materials in three dimensions. for the interface between a metal and a topological insulator the magnetic polarization of the surface plasmon is rotated out of the plane of the interface ; this effect should be experimentally observable by exciting the surface plasmon with polarized light. more interestingly, we argue that the same effect also is realized on the interface between vacuum and a doped topological insulator with non - vanishing bulk carrier density.
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arxiv:1104.4125
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magnetic resonance microscopy images at cellular resolution ( < 10 microns ) are limited by diffusion. snr and spatial resolution suffer from the dephasing of transverse magnetization caused by diffusion of spins in strong gradients. such effects may be reduced by using phase encoding instead of frequency encoding readout gradients. demonstration of the benefits of phase encoding are lacking, and the conditions in which it is preferred are not clearly established. we quantify when phase encoding outperforms a readout gradient with emphasis on the detrimental effects of diffusion on snr and resolution. a 15. 2t mri scanner, with 1 t / m gradients, and micro solenoid rf coils < 1 mm in diameter, were used to quantify diffusion effects on resolution and snr of frequency and phase encoded acquisitions. frequency and phase encoding resolution and snr per square root time were calculated and measured for images at the diffusion limited resolution. the point - spread - function was measured for phase and frequency encoding using additional constant time gradients with voxels 3 - 15 microns. the effect of diffusion during the readout gradient on snr was experimentally demonstrated. the achieved resolutions of frequency and phase encoded acquisitions were measured via the point - spread - function. snr per square root time and actual resolution were calculated for a wide range of gradient amplitudes, diffusion coefficients, and relaxation properties. the results provide a practical guide on how to choose between phase and frequency encoding. images of excised rat spinal cord at 10 x 10 microns in - plane demonstrate benefits of phase encoding in the form of higher measured resolution and snr vs the same image acquired with a conventional readout. we demonstrate the extent to which phase encoding outperforms readout gradients in snr and resolution over a wide range of voxel sizes, sample, and hardware properties.
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arxiv:2301.00727
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the second hardy - littlewood conjecture, that $ \ pi ( x ) + \ pi ( y ) \ geq \ pi ( x + y ) $ for integers $ x $ and $ y $ with $ \ min \ { x, y \ } \ geq 2 $, was formulated in 1923. it continues to attract attention to this day, almost 100 years later. in 1975 udrescu proved that this conjecture holds for $ ( x, y ) $ sufficiently large, but without an explicit effective bound on the region of validity. we shall revisit udrescu ' s result, modifying it to obtain explicit effective bounds, ultimately proving that the second hardy - littlewood conjecture is in fact unconditionally true. furthermore we note that constraints on the prime counting function imply, ( and are implied by ), constraints on the location of the primes, and re - cast segal ' s 1962 equivalent reformulation of the second hardy - littlewood conjecture in the more symmetric ( and perhaps clearer ) form that for integers $ i $ and $ j $ with $ \ min \ { i, j \ } \ geq 2 $ one has $ p _ { i + j - 1 } \ geq p _ i + p _ j - 1 $.
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arxiv:2101.03283
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instead of randomly acquiring training data points, uncertainty - based active learning ( ual ) operates by querying the label ( s ) of pivotal samples from an unlabeled pool selected based on the prediction uncertainty, thereby aiming at minimizing the labeling cost for model training. the efficacy of ual critically depends on the model capacity as well as the adopted uncertainty - based acquisition function. within the context of this study, our analytical focus is directed toward comprehending how the capacity of the machine learning model may affect ual efficacy. through theoretical analysis, comprehensive simulations, and empirical studies, we conclusively demonstrate that ual can lead to worse performance in comparison with random sampling when the machine learning model class has low capacity and is unable to cover the underlying ground truth. in such situations, adopting acquisition functions that directly target estimating the prediction performance may be beneficial for improving the performance of ual.
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arxiv:2408.13690
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we propose a generalisation of analytic in a domain function of bounded index, which was introduced by j. g. krishna and s. m. shah \ cite { krishna }. in fact, analytic in the unit ball function of bounded index by krishna and shah is an entire function. our approach allows us to explore properties of analytic in the unit ball functions. we proved the necessary and sufficient conditions of bounded $ l $ - index in direction for analytic functions. as a result, they are applied to study partial differential equations and get sufficient conditions of bounded $ l $ - index in direction for analytic solutions. finally, we estimated growth for these functions.
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arxiv:1501.04166
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bray ' s football theorem ( \ cite { bray2009penrose } ) is a weakening of bishop theorem in dimension 3. it gives a sharp volume upper bound for a three dimensional manifold with scalar curvature larger than $ n ( n - 1 ) $ and ricci curvature larger than $ \ varepsilon $. this paper extends bray ' s football theorem in high dimensions, assuming the manifold is axis symmetric or the ricci curvature has an upper bound.
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arxiv:1909.00909
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using discrete simulations, we investigate the behavior of a model granular material within an annular shear cell. specifically, two - dimensional assemblies of disks are placed between two circular walls, the inner one rotating with prescribed angular velocity, while the outer one may expand or shrink and maintains a constant radial pressure. focusing on steady state flows, we delineate in parameter space the range of applicability of the recently introduced constitutive laws for sheared granular materials ( based on the inertial number ). we discuss the two origins of the stronger strain rates observed near the inner boundary, the vicinity of the wall and the heteregeneous stress field in a couette cell. above a certain velocity, an inertial region develops near the inner wall, to which the known constitutive laws apply, with suitable corrections due to wall slip, for small enough stress gradients. away from the inner wall, slow, apparently unbounded creep takes place in the nominally solid material, although its density and shear to normal stress ratio are on the jammed side of the critical values. in addition to rheological characterizations, our simulations provide microscopic information on the contact network and velocity fluctuations that is potentially useful to assess theoretical approaches.
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arxiv:0901.2060
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side channels pose a significant threat to the confidentiality of software systems. such vulnerabilities are challenging to detect and evaluate because they arise from non - functional properties of software such as execution times and require reasoning on multiple execution traces. recently, noninterference notions have been adapted in static analysis, symbolic execution, and greybox fuzzing techniques. however, noninterference is a strict notion and may reject security even if the strength of information leaks are weak. a quantitative notion of security allows for the relaxation of noninterference and tolerates small ( unavoidable ) leaks. despite progress in recent years, the existing quantitative approaches have scalability limitations in practice. in this work, we present qfuzz, a greybox fuzzing technique to quantitatively evaluate the strength of side channels with a focus on min entropy. min entropy is a measure based on the number of distinguishable observations ( partitions ) to assess the resulting threat from an attacker who tries to compromise secrets in one try. we develop a novel greybox fuzzing equipped with two partitioning algorithms that try to maximize the number of distinguishable observations and the cost differences between them. we evaluate qfuzz on a large set of benchmarks from existing work and real - world libraries ( with a total of 70 subjects ). qfuzz compares favorably to three state - of - the - art detection techniques. qfuzz provides quantitative information about leaks beyond the capabilities of all three techniques. crucially, we compare qfuzz to a state - of - the - art quantification tool and find that qfuzz significantly outperforms the tool in scalability while maintaining similar precision. overall, we find that our approach scales well for real - world applications and provides useful information to evaluate resulting threats. additionally, qfuzz identifies a zero - d...
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arxiv:2106.03346
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weather routing methods are essential for planning routes for commercial shipping and recreational craft. this paper provides a methodology for quantifying the significance of numerical error and performance model uncertainty on the predictions returned from a weather routing algorithm. the numerical error of the routing algorithm is estimated by solving the optimum path over different discretizations of the environment. the uncertainty associated with the performance model is linearly varied in order to quantify its significance. the methodology is applied to a sailing craft routing problem : the prediction of the voyaging time for an ethnographic voyaging canoe across long distance voyages in polynesia. we find that the average numerical error is $ 0. 396 \ % $, corresponding to $ 1. 05 $ hours for an average voyage length of $ 266. 40 $ hours. an uncertainty level of $ 2. 5 \ % $ in the performance model is seen to correspond to a standard deviation of $ \ pm 2. 41 - 3. 08 \ % $ of the voyaging time. these results illustrate the significance of considering the influence of numerical error and performance uncertainty when performing a weather routing study.
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arxiv:1901.03840
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we consider a class of stochastic impulse control problems of general stochastic processes i. e. not necessarily markovian. under fairly general conditions we establish existence of an optimal impulse control. we also prove existence of combined optimal stochastic and impulse control of a fairly general class of diffusions with random coefficients. unlike, in the markovian framework, we cannot apply quasi - variational inequalities techniques. we rather derive the main results using techniques involving reflected bsdes and the snell envelope.
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arxiv:0806.2761
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let $ k, l $ be nonnegative integers. a graph $ g $ is $ ( k, l ) $ - polar if its vertex set admits a partition $ ( a, b ) $ such that $ a $ induces a complete multipartite graph with at most $ k $ parts, and $ b $ induces a disjoint union of at most $ l $ cliques with no other edges. a graph is a cograph if it does not contain $ p _ 4 $ as an induced subgraph. it is known that $ ( k, l ) $ - polar cographs can be characterized through a finite family of forbidden induced subgraphs, for any fixed choice of $ k $ and $ l $. the problem of determining the exact members of such family for $ k = 2 = l $ was posted by ekim, mahadev and de werra, and recently solved by hell, linhares - sales and the second author of this paper. so far, complete lists of such forbidden induced subgraphs are known for $ 0 \ le k, l \ le 2 $ ; notice that, in particular, $ ( 1, 1 ) $ - polar graphs are precisely split graphs. in this paper, we focus on this problem for $ ( s, 1 ) $ - polar cographs. as our main result, we provide a recursive complete characterization of the forbidden induced subgraphs for $ ( s, 1 ) $ - polar cographs, for every non negative integer $ s $. additionally, we show that cographs having an $ ( s, 1 ) $ - partition for some integer $ s $ ( here $ s $ is not fixed ) can be characterized by forbidding a family of four graphs.
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arxiv:2104.07856
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we propose a provably convergent method, called efficient learned descent algorithm ( elda ), for low - dose ct ( ldct ) reconstruction. elda is a highly interpretable neural network architecture with learned parameters and meanwhile retains convergence guarantee as classical optimization algorithms. to improve reconstruction quality, the proposed elda also employs a new non - local feature mapping and an associated regularizer. we compare elda with several state - of - the - art deep image methods, such as red - cnn and learned primal - dual, on a set of ldct reconstruction problems. numerical experiments demonstrate improvement of reconstruction quality using elda with merely 19 layers, suggesting the promising performance of elda in solution accuracy and parameter efficiency.
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arxiv:2104.12939
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several problems with the diagnostic check suggested by pena and rodriguez [ 2002. a powerful portmanteau test of lack of fit for time series. j. amer. statist. assoc. 97, 601 - 610. ] are noted and an improved monte - carlo version of this test is suggested. it is shown that quite often the test statistic recommended by pena and rodriguez [ 2002. a powerful portmanteau test of lack of fit for time series. j. amer. statist. assoc. 97, 601 - 610. ] may not exist and their asymptotic distribution of the test does not agree with the suggested gamma approximation very well if the number of lags used by the test is small. it is shown that the convergence of this test statistic to its asymptotic distribution may be quite slow when the series length is less than 1000 and so a monte - carlo test is recommended. simulation experiments suggest the monte - carlo test is usually more powerful than the test given by pena and rodriguez [ 2002. a powerful portmanteau test of lack of fit for time series. j. amer. statist. assoc. 97, 601 - 610. ] and often much more powerful than the ljung - box portmanteau test. two illustrative examples of enhanced diagnostic checking with the monte - carlo test are given.
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arxiv:1611.01351
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we study hyperbolic skew products and the disintegration of the srb measure into measures supported on local stable manifolds. such a disintegration gives a method for passing from an observable $ v $ on the skew product to an observable $ \ bar v $ on the system quotiented along stable manifolds. under mild assumptions on the system we prove that the disintegration preserves the smoothness of $ v $, firstly in the case where $ v $ is h \ " older and secondly in the case where $ v $ is $ \ mathcal { c } ^ { 1 } $.
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arxiv:1503.04319
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mobility support for the next generation ipv6 networks has been one of the recent research issues due to the growing demand for wireless services over internet. in the other hand, 3gpp has introduced ip multimedia subsystem as the next generation ip based infrastructure for wireless and wired multimedia services. in this paper we present two context transfer mechanisms based on predictive and reactive schemes, to support seamless handover in ims over mobile ipv6. those schemes reduce handover latency by transferring appropriate session information between the old and the new access networks. moreover, we present two methods for qos parameters negotiations to preserve service quality along the mobile user movement path. the performances of the proposed mechanisms are evaluated by simulations.
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arxiv:1208.1207
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in the precedent paper of the authors ( hep - ph / 0510410 ), the $ b \ bar b $ states were treated in the framework of the spectral integral equation, together with simultaneous calculations of radiative decays of the considered bottomonia. in the present paper, such a study is carried out for the charmonium $ ( c \ bar c ) $ states. we reconstruct the interaction in the $ c \ bar c $ - sector on the basis of data for the charmonium levels with $ j ^ { pc } = 0 ^ { - + } $, $ 1 ^ { - - } $, $ 0 ^ { + + } $, $ 1 ^ { + + } $, $ 2 ^ { + + } $, $ 1 ^ { + - } $ and radiative transitions $ \ psi ( 2s ) \ to \ gamma \ chi _ { c0 } ( 1p ) $, $ \ gamma \ chi _ { c1 } ( 1p ) $, $ \ gamma \ chi _ { c2 } ( 1p ) $, $ \ gamma \ eta _ { c } ( 1s ) $ and $ \ chi _ { c0 } ( 1p ) $, $ \ chi _ { c1 } ( 1p ) $, $ \ chi _ { c2 } ( 1p ) \ to \ gamma j / \ psi $. the $ c \ bar c $ levels and their wave functions are calculated for the radial excitations with $ n \ le 6 $. also, we determine the $ c \ bar c $ component of the photon wave function using the $ e ^ + e ^ - $ annihilation data : $ e ^ + e ^ - \ to j / \ psi ( 3097 ) $, $ \ psi ( 3686 ) $, $ \ psi ( 3770 ) $, $ \ psi ( 4040 ) $, $ \ psi ( 4160 ) $, $ \ psi ( 4415 ) $ and perform the calculations of the partial widths of the two - photon decays for the $ n = 1 $ states : $ \ eta _ { c0 } ( 1s ) $, $ \ chi _ { c0 } ( 1p ) $, $ \ chi _ { c2 } ( 1p ) \ to \ gamma \ gamma $, and $ n = 2 $ states : $ \ eta _ { c0 } ( 2s ) \ to \ gamma \ gamma $,
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arxiv:hep-ph/0511005
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we study the energies and optical spectra of excitons in twisted bilayers of anisotropic van der waals semiconductors exhibiting moir \ ' e patterns, taking phosphorene as a case study. following the electronic hamiltonian introduced by us in [ phys. rev. b 105, 235421 ( 2022 ) ], and leveraging the scale separation between the moir \ ' e lengthscale and the exciton bohr radii, we introduce a continuous model for excitons that incorporates the spatial variation of their binding energies. our zone - folding calculations reveal a dimensionality crossover for the exciton states, driven by the combined dispersion - and moir \ ' e potential anisotropies, from quantum - dot - like ( 0d ) lattices at twist angles $ \ theta < \ theta _ * $, to quantum - wire - like ( 1d ) arrays at $ \ theta > \ theta _ * $, with crossover angle $ \ theta _ * = 4 ^ \ circ $. we identify clear signatures of this dimensionality crossover in the twist angle dependence of the excitonic absorption spectra, which allows experimental verification of our theoretical results through standard optical measurements. our results establish two - dimensional anisotropic moir \ ' e semiconductors as versatile solid - state platforms for exploring bosonic correlations across different dimensionalities.
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arxiv:2308.03294
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we describe a microwave photon counter based on the current - biased josephson junction. the junction is tuned to absorb single microwave photons from the incident field, after which it tunnels into a classically observable voltage state. using two such detectors, we have performed a microwave version of the hanbury brown and twiss experiment at 4 ghz and demonstrated a clear signature of photon bunching for a thermal source. the design is readily scalable to tens of parallelized junctions, a configuration that would allow number - resolved counting of microwave photons.
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arxiv:1011.4329
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a new space namely the weyl - kahler is proposed to the quantum state space. some of the physical consequences are discussed.
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arxiv:quant-ph/0109048
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the accurate and efficient modeling of granular flows and their interactions with external bodies is an open research problem. continuum methods can be used to capture complexities neglected by terramechanics models without the computational expense of discrete element methods. constitutive models and numerical solvers are the two primary aspects of the continuum methods. the viscoplastic size - dependent non - local granular fluidity ( ngf ) constitutive model has successfully provided a quantitative description of experimental flows in many different configurations in literature. this research develops a numerical approach, within a hyperelasticity framework, for implementing the dynamical form of ngf in three - dimensional material point method ( 3d mpm, an appropriate numerical solver for granular flow modeling ). this approach is thermodynamically consistent to conserve energy, and the dynamical form includes the nonlocal effect of flow cessation. excavation data, both quantitative measurements and qualitative visualization, are collected experimentally via our robotic equipment to evaluate the model with respect to the flow geometry as well as interaction forces. the results are further compared with the results from a recent modified plastic drucker - prager constitutive model, and in other configurations including wheel - soil interactions, a gravity - driven silo, and taylor - couette flow.
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arxiv:2111.01523
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symbolic regression ( sr ) is a data analysis problem where we search for the mathematical expression that best fits a numerical dataset. it is a global optimization problem. the most popular approach to sr is by genetic programming ( srgp ). it is a common paradigm to compare an algorithm ' s performance to that of random search, but the data comparing srgp to random search is lacking. we describe a novel algorithm for sr, namely sr by uniform random global search ( srurgs ), also known as pure random search. we conduct experiments comparing srurgs with srgp using 100 randomly generated equations. our results suggest that a srgp is faster than srurgs in producing equations with good r ^ 2 for simple problems. however, our experiments suggest that srurgs is more robust than srgp, able to produce good output in more challenging problems. as srurgs is arguably the simplest global search algorithm, we believe it should serve as a control algorithm against which other symbolic regression algorithms are compared. srurgs has only one tuning parameter, and is conceptually very simple, making it a useful tool in solving sr problems. the method produces random equations, which is useful for the generation of symbolic regression benchmark problems. we have released well documented and open - source python code, currently under formal peer - review, so that interested researchers can deploy the tool in practice.
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arxiv:1906.07848
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under losses which are potentially heavy - tailed, we consider the task of minimizing sums of the loss mean and standard deviation, without trying to accurately estimate the variance. by modifying a technique for variance - free robust mean estimation to fit our problem setting, we derive a simple learning procedure which can be easily combined with standard gradient - based solvers to be used in traditional machine learning workflows. empirically, we verify that our proposed approach, despite its simplicity, performs as well or better than even the best - performing candidates derived from alternative criteria such as cvar or dro risks on a variety of datasets.
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arxiv:2301.11584
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the question of how supermassive black holes ( smbhs ) grow over cosmic time is a major puzzle in high - energy astrophysics. one promising approach to this problem is via the study of tidal disruption flares ( tdfs ). these are transient events resulting from the disruption of stars by quiescent supermassive black holes at centers of galaxies. a meter - class x - ray observatory with a time resolution $ \ sim $ a millisecond and a spectral resolution of a few ev at kev energies would be revolutionary as it will facilitate high signal to noise spectral - timing studies of several cosmological tdfs. it would open a new era of astrophysics where smbhs in tdfs at cosmic distances can be studied in similar detail as current studies of much nearer, stellar - mass black hole binaries. using athena x - ray observatory as an example, we highlight two specific aspects of spectral - timing analysis of tdfs. ( 1 ) detection of x - ray quasi - periodic oscillations ( qpos ) over a redshift range and using these signal frequencies to constrain the spin evolution of smbhs, and ( 2 ) time - resolved spectroscopy of outflows / winds to probe super - eddington accretion. smbh spin distributions at various redshifts will directly allow us to constrain their primary mode of growth as higher spins are predicted due to spin - up for prolonged accretion - mode growth, while lower spins are expected for growth via mergers due to angular momentum being deposited from random directions. a meter - class x - ray telescope will also be able to characterize relativistic tdfs, viz., swj1644 + 57 - like events, out to a redshift greater than 8, i. e., it would facilitate detailed spectral - timing studies of tdfs by the youngest smbhs in the universe.
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arxiv:1903.02584
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in this article we extend work of shanks and washington on cyclic extensions, and elliptic curves associated to the simplest cubic fields. in particular, we give families of examples of hyperelliptic curves $ c : y ^ 2 = f ( x ) $ defined over $ \ mathbb { q } $, with $ f ( x ) $ of degree $ p $, where $ p $ is a sophie germain prime, such that the rank of the mordell - - weil group of the jacobian $ j / \ mathbb { q } $ of $ c $ is bounded by the genus of $ c $ and the $ 2 $ - rank of the class group of the ( cyclic ) field defined by $ f ( x ) $, and exhibit examples where this bound is sharp.
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arxiv:1708.07896
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the two long - baseline experiments icarus and opera have recently provided bounds on light ( $ \ sim $ ev ) sterile neutrinos exploiting the negative results of the $ \ nu _ \ mu \ to \ nu _ e $ appearance searches. both collaborations have performed the data analysis using an effective 2 - flavor description. we show that such a simplified treatment neglects sizable genuine 4 - flavor effects, which are induced by the interference of the new large squared - mass splitting $ \ delta m ^ 2 _ { 14 } $ with the atmospheric one. the inclusion in the data analysis of such effects weakens the upper bounds on the effective appearance amplitude $ \ sin ^ 2 2 \ theta _ { \ mu e } $ approximately by a factor of two. in addition, we evidence that, in a 4 - flavor scheme, the flavor oscillations involve also the $ \ nu _ e $ component of the cngs beam and can suppress the theoretical expectation of the background in a substantial way. the inclusion in the data analysis of the $ \ nu _ e $ disappearance effects leads to a further weakening of the upper bounds on $ \ sin ^ 2 2 \ theta _ { \ mu e } $, which overall are relaxed by a factor of three with respect to those obtained in the effective 2 - flavor description.
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arxiv:1503.03966
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in this paper, we study the problem of a batch of linearly correlated image alignment, where the observed images are deformed by some unknown domain transformations, and corrupted by additive gaussian noise and sparse noise simultaneously. by stacking these images as the frontal slices of a third - order tensor, we propose to utilize the tensor factorization method via transformed tensor - tensor product to explore the low - rankness of the underlying tensor, which is factorized into the product of two smaller tensors via transformed tensor - tensor product under any unitary transformation. the main advantage of transformed tensor - tensor product is that its computational complexity is lower compared with the existing literature based on transformed tensor nuclear norm. moreover, the tensor $ \ ell _ p $ $ ( 0 < p < 1 ) $ norm is employed to characterize the sparsity of sparse noise and the tensor frobenius norm is adopted to model additive gaussian noise. a generalized gauss - newton algorithm is designed to solve the resulting model by linearizing the domain transformations and a proximal gauss - seidel algorithm is developed to solve the corresponding subproblem. furthermore, the convergence of the proximal gauss - seidel algorithm is established, whose convergence rate is also analyzed based on the kurdyka - $ \ l $ ojasiewicz property. extensive numerical experiments on real - world image datasets are carried out to demonstrate the superior performance of the proposed method as compared to several state - of - the - art methods in both accuracy and computational time.
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arxiv:2212.05719
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we present the first - ever rotationally resolved spectroscopic investigation of ( 624 ) hektor and ( 911 ) agamemnon, the two largest jupiter trojans. the visible and near - infrared spectra that we have obtained at the tng telescope ( la palma, spain ) do not show any feature or hints of heterogeneity. in particular we found no hints of water - related absorptions. no cometary activity was detected down to ~ 23. 5 r - mag / arcsec2 based on the complementary photometric data. we estimated upper limits on the dust production rates of hektor and agamemnon to be ~ 30 kg / s and ~ 24 kg / s, respectively. we modelled complete visible and near - infrared spectra of our targets using the shkuratov formalism, to define the upper limit to the presence of water ice and more in general to constrain their surface composition. for both objects, successful models include amorphous carbon, magnesium - rich pyroxene and kerogen, with an upper limit to the amount of water ice of a few percent.
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arxiv:1712.08502
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context : software development analytics is a research area concerned with providing insights to improve product deliveries and processes. many types of studies, data sources and mining methods have been used for that purpose. objective : this systematic literature review aims at providing an aggregate view of the relevant studies on software development analytics in the past decade, with an emphasis on its application in practical settings. method : definition and execution of a search string upon several digital libraries, followed by a quality assessment criteria to identify the most relevant papers. on those, we extracted a set of characteristics ( study type, data source, study perspective, development life - cycle activities covered, stakeholders, mining methods, and analytics scope ) and classified their impact against a taxonomy. results : source code repositories, experimental case studies, and developers are the most common data sources, study types, and stakeholders, respectively. product and project managers are also often present, but less than expected. mining methods are evolving rapidly and that is reflected in the long list identified. descriptive statistics are the most usual method followed by correlation analysis. being software development an important process in every organization, it was unexpected to find that process mining was present in only one study. most contributions to the software development life cycle were given in the quality dimension. time management and costs control were lightly debated. the analysis of security aspects suggests it is an increasing topic of concern for practitioners. risk management contributions are scarce. conclusions : there is a wide improvement margin for software development analytics in practice. for instance, mining and analyzing the activities performed by software developers in their actual workbench, the ide.
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arxiv:2007.10213
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we use leading order effective kinetic theory to simulate the pre \ nobreakdash - equilibrium evolution of transverse energy and flow perturbations in heavy - ion collisions. we provide a green function which propagates the initial perturbations of the energy - momentum tensor to a time when hydrodynamics becomes applicable. with this map, the pre - thermal evolution from saturated nuclei to hydrodynamics can be modeled in the framework of weakly coupled qcd.
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arxiv:1610.09912
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in this work, a generalization of the well known bernoulli inequality is obtained by using the theory of discrete fractional calculus. as far as we know our approach is novel.
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arxiv:1702.00265
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this paper deals with a source separation strategy based on second - order statistics, namely, on data covariance matrices estimated at several lags. in general, ` ` blind ' ' approaches to source separation do not assume any knowledge on the mixing operator ; however, any prior information about the possible structure of the mixing operator can improve the solution. unlike ica blind separation approaches, where mutual independence between the sources is assumed, our method only needs to constrain second - order statistics, and is effective even if the original sources are significantly correlated. besides the mixing matrix, our strategy is also capable to evaluate the source covariance functions at several lags. moreover, once the mixing parameters have been identified, a simple deconvolution can be used to estimate the probability density functions of the source processes. to benchmark our algorithm, we used a database that simulates the one expected from the instruments that will operate onboard esa ' s planck surveyor satellite to measure the cmb anisotropies all over the celestial sphere. the assumption was made that the emission spectra of the galactic foregrounds can be parametrised, thus reducing the number of unknowns for system identification to the number of the foreground radiations. we performed separation in several sky patches, featuring different levels of galactic contamination to the cmb, and assuming several noise levels, including the ones derived from the planck specifications.
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arxiv:astro-ph/0407108
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we consider a stable cox - - ingersoll - - ross process driven by a standard wiener process and a spectrally positive strictly stable l \ ' evy process, and we study asymptotic properties of the maximum likelihood estimator ( mle ) for its growth rate based on continuous time observations. we distinguish three cases : subcritical, critical and supercritical. in all cases we prove strong consistency of the mle in question, in the subcritical case asymptotic normality, and in the supercritical case asymptotic mixed normality are shown as well. in the critical case the description of the asymptotic behavior of the mle in question remains open.
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arxiv:1711.02140
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sx phoenicis ( sxp ) variables are short period pulsating stars that exhibit a period - luminosity ( pl ) relation. we derived the gri - band pl and extinction - free period - wesenheit ( pw ) relations, as well as the period - color ( pc ) and reddening - free period - q - index ( pq ) relations for 47 sxp stars in located in 21 globular clusters using the optical light curves taken from zwicky transient facility ( ztf ). these empirically relations were derived for the first time in the gri filters except for the g - band pl relation. we used our gi band pl and pw relations to derive a distance modulus to crater ii dwarf spheroidal which hosts one sxp variable. assuming that the fundamental and first - overtone pulsation mode for the sxp variable in crater ii, we found distance moduli of $ 20. 03 \ pm 0. 23 $ mag and $ 20. 37 \ pm 0. 24 $ mag, respectively, using the pw relation, where the latter is in excellent agreement with independent rr lyrae based distance to crater ii dwarf galaxy.
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arxiv:2303.07554
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changes on temperature patterns, on a local scale, are perceived by individuals as the most direct indicators of global warming and climate change. as a specific example, for an atlantic climate location, spring and fall seasons should present a mild transition between winter and summer, and summer and winter, respectively. by observing daily temperature curves along time, being each curve attached to a certain calendar day, a regression model for these variables ( temperature curve as covariate and calendar day as response ) would be useful for modeling their relation for a certain period. in addition, temperature changes could be assessed by prediction and observation comparisons in the long run. such a model is presented and studied in this work, considering a nonparametric nadaraya - watson - type estimator for functional covariate and circular response. the asymptotic bias and variance of this estimator, as well as its asymptotic distribution are derived. its finite sample performance is evaluated in a simulation study and the proposal is applied to investigate a real - data set concerning temperature curves.
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arxiv:2205.12565
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pre - trained vision - language models ( vlms ), such as clip, demonstrate impressive zero - shot classification capabilities with free - form prompts and even show some generalization in specialized domains. however, their performance on satellite imagery is limited due to the underrepresentation of such data in their training sets, which predominantly consist of ground - level images. existing prompting techniques for satellite imagery are often restricted to generic phrases like a satellite image of..., limiting their effectiveness for zero - shot land - use and land - cover ( lulc ) mapping. to address these challenges, we introduce senclip, which transfers clips representation to sentinel - 2 imagery by leveraging a large dataset of sentinel - 2 images paired with geotagged ground - level photos from across europe. we evaluate senclip alongside other sota remote sensing vlms on zero - shot lulc mapping tasks using the eurosat and bigearthnet datasets with both aerial and ground - level prompting styles. our approach, which aligns ground - level representations with satellite imagery, demonstrates significant improvements in classification accuracy across both prompt styles, opening new possibilities for applying free - form textual descriptions in zero - shot lulc mapping.
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arxiv:2412.08536
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we prove that for any field k of characteristic p > 0, any separated scheme x of finite type over k, and any overconvergent f - isocrystal e over x, the rigid cohomology h ^ i ( x, e ) and rigid cohomology with compact supports h ^ i _ c ( x, e ) are finite dimensional vector spaces. we also establish poincare duality and the kunneth formula with coefficients. the arguments use a pushforward construction in relative dimension 1, based on a relative version of crew ' s conjecture on the quasi - unipotence of certain p - adic differential equations.
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arxiv:math/0208027
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cheeger and gromov showed that f - structures are related to collapse with a double - sided curvature bound. we define fibered f - structures and extend some of the cheeger - gromov results to the setting of collapse with a lower bound on the curvature operator.
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arxiv:1204.6677
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we refine a result of the last two authors of [ 8 ] on a diophantine approximation problem with two primes and a $ k $ - th power of a prime which was only proved to hold for $ 1 < k < 4 / 3 $. we improve the $ k $ - range to $ 1 < k \ le 3 $ by combining harman ' s technique on the minor arc with a suitable estimate for the $ l ^ 4 $ - norm of the relevant exponential sum over primes $ s _ k $. in the common range we also give a stronger bound for the approximation.
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arxiv:1706.00343
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economies are complex man - made systems where organisms and markets interact according to motivations and principles not entirely understood yet. the increasing dissatisfaction with the postulates of traditional economics i. e. perfectly rational agents, interacting through efficient markets in the search of equilibrium, has created new incentives for different approaches in economics. the science of complexity may provide the platform to cross disciplinary boundaries in seemingly disparate fields such as brain science and economics. in this paper we take an integrative stance, fostering new insights into the economic character of neural activity. the objective here is to precisely delineate common topics in both neural and economic science, within a systemic outlook grounded in empirical basis that jolts the unification across the science of complex systems. it is argued that this mainly relies on the study of the inverse problem in complex system with a truly bayesian approach.
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arxiv:1205.2999
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federated learning is an emerging privacy - preserving distributed machine learning that enables multiple parties to collaboratively learn a shared model while keeping each party ' s data private. however, federated learning faces two main problems : semi - honest server privacy inference attacks and malicious client - side model theft. to address privacy inference attacks, parameter - based encrypted federated learning secure aggregation can be used. to address model theft, a watermark - based intellectual property protection scheme can verify model ownership. although watermark - based intellectual property protection schemes can help verify model ownership, they are not sufficient to address the issue of continuous model theft by uncaught malicious clients in federated learning. existing ip protection schemes that have the ability to track traitors are also not compatible with federated learning security aggregation. thus, in this paper, we propose a federated client - side intellectual property protection ( fedcip ), which is compatible with federated learning security aggregation and has the ability to track traitors. to the best of our knowledge, this is the first ip protection scheme in federated learning that is compatible with secure aggregation and tracking capabilities.
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arxiv:2306.01356
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this report describes the development of an aptamer for sensing azole antifungal drugs for therapeutic drug monitoring. modified synthetic evolution of ligands through exponential enrichment ( selex ) was used to discover a dna aptamer recognizing azole class antifungal drugs. this aptamer undergoes a secondary structural change upon binding to its target molecule as shown through fluorescence anisotropy - based binding measurements. experiments using circular dichroism spectroscopy, revealed a unique double g - quadruplex structure that was essential and specific for binding to the azole antifungal target. aptamer - functionalized graphene field effect transistor ( gfet ) devices were created and used to measure the binding of strength of azole antifungals to this surface. in total this aptamer and the supporting sensing platform could provide a valuable tool for improving the treatment of patients with invasive fungal infections.
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arxiv:1708.08974
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the atomic ionization processes induced by scattering of neutrinos play key roles in the experimental searches for a neutrino magnetic moment. current experiments with reactor ( anti ) neutrinos employ germanium detectors having energy threshold comparable to typical binding energies of atomic electrons, which fact must be taken into account in the interpretation of the data. our theoretical analysis shows that the so - called stepping approximation to the neutrino - impact ionization is well applicable for the lowest bound coulomb states, and it becomes exact in the semiclassical limit. numerical evidence is presented using the thomas - fermi model for the germanium atom.
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arxiv:1105.5543
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we use observations and simulation to study the relationship between star - forming galaxies and the intergalactic medium at z ~ 3. the observed galaxy sample is based on spectroscopic redshift data from a combination of the vlt lbg redshift survey and keck observations in fields centred on bright z > 3 qsos, whilst the simulation data is taken from gimic. in the simulation, we find that the dominant peculiar velocities are in the form of large - scale coherent motions of gas and galaxies. gravitational infall of galaxies towards one another is also seen. at smaller scales, the peculiar velocities in the simulation over - predict the difference between the simulated real - and z - space galaxy correlation functions. peculiar velocity pairs separated by < 1mpc / h have a smaller dispersion and explain the z - space correlation function better. the ly { \ alpha } auto - and cross - correlation functions in the gimic simulation show infall smaller than implied by previous work. this reduced infall may be due to the galaxy wide outflows implemented in the simulation. the main challenge in comparing these simulated results with the observed correlation functions comes from the presence of velocity errors for the observed lbgs which dominate at ~ 1mpc / h scales. when these are taken into account, the observed lbg correlation function is well matched by a simulated $ m _ * > 10 ^ 9m _ \ odot $ galaxy sample. the simulated cross - correlation shows similar neutral gas densities around galaxies as are seen in the observations. the simulated and observed ly { \ alpha } z - space autocorrelation functions agree well with each other. our overall conclusion is that gas and galaxy peculiar velocities are towards the low end of expectation. finally, little direct evidence is seen in either simulation or observations for high transmission near galaxies due to feedback. ( abridged )
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arxiv:1304.4598
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topological phases exhibit properties that are conserved for continuous deformations, as demonstrated in topological protections in condensed - matter physics and electromagnetic waves. despite its ubiquitous nature and recent extensions to synthetic dimensions, non - hermitian hamiltonians, and nonlinear dynamics, topological protection has generally been described in spatial lattices with the chern number in the brillouin zone, focusing on the realization of backscattering - free wave transport. here, we investigate a different class of topological protection in parity - time - symmetric nonlinear optical dynamics, exploiting the topological invariance of optical state trajectories. for coupled nonlinear photonic systems composed of gain and loss atoms, we classify the topology of equilibria separately for unbroken and broken parity - time symmetry. utilizing the immunity of topological phases against temporal perturbations, we develop noise - immune laser modulation and rectification with a parasitic nonlinear resonator based on oscillation quenching mechanisms that are protected by parity - time symmetry. the connection between topological photonics and parity - time symmetry through nonlinear dynamics provides a powerful platform for noise - immune signal processing.
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arxiv:2003.07005
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in this paper we extend the projective symmetry of the full metric - affine einstein - hilbert theory to a new symmetry transformation in the space of affine connections called the amplified symmetry. we prove that the lagrangian of the standard model of particle physics is invariant under this new symmetry. we also show that the gravitational lagrangian can be modified so that the amplified symmetry extends to the gravitational sector and hence to the whole action. the new theory so constructed is shown to be dynamically equivalent to einstein - cartan ' s though genuinely metric - affine.
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arxiv:2006.04040
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this is a matricial description of all the fine group gradings on the exceptional lie algebra $ o ( 8, \ mathbb c ) $. there are fourteen.
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arxiv:0709.0194
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how much dark matter is there in the universe and where is it located? these are two of the most fundamental questions in cosmology. we use in this paper optical and x - ray mass determinations of galaxies, groups, and clusters of galaxies to suggest that most of the dark matter may reside in very large halos around galaxies, typically extending to ~ 200 kpc for bright galaxies. we show that the mass - to - light ratio of galaxy systems does not increase significantly with linear scale beyond the very large halos suggested for individual galaxies. rather, the total mass of large scale systems such as groups and rich clusters of galaxies, even superclusters, can on average be accounted for by the total mass of their member galaxies, including their large halos ( which may be stripped - off in the dense cluster environment but still remain in the clusters ) plus the mass of the hot intracluster gas. this conclusion also suggests that we may live in a low - density universe with omega ~ 0. 2 - 0. 3.
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arxiv:astro-ph/9506041
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we present results of a hubble space telescope ( hst ) ubvi - band study of star clusters in tidal tails, using new wfc3 and acs imaging to complement existing wfpc2 data. we survey 12 tidal tails across seven merging systems, deriving ages and masses for 425 star cluster candidates ( sccs ). the stacked mass distribution across all systems follows a power law of the form $ dn / dm \ propto m ^ { \ beta } $, with $ \ beta = - 2. 02 \ pm 0. 15 $, consistent with what is seen in other star forming environments. galex and swift uv imaging provide star formation rates ( sfrs ) for our tidal tails, which when compared with ages and masses of our sccs, allows for a determination of the cluster formation efficiency ( cfe ). we find the cfe increases with increasing sfr surface density, matching the theoretical model. we confirm this fit down at sfr densities lower than previously measured ( log $ \ sigma _ \ text { sfr } \ : ( \ text { m } _ \ odot \ : \ text { yr } ^ { - 1 } \ : \ text { kpc } ^ { - 2 } ) \ approx - 4. 2 $ ), as related to the cfe. we determine the half - light radii for a refined sample of 57 sccs with our hst wfc3 and acs imaging, and calculate their dynamical age, finding the majority of them to be gravitationally bound. we also provide evidence of only low - mass ( $ < 10 ^ 4 \ : \ text { m } _ \ odot $ ) cluster formation in our nearest galaxy, ngc 1487, consistent with the theory that this system is a dwarf merger.
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arxiv:2309.10267
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we develop a tight - binding model description of semi - dirac electronic spectra, with highly anisotropic dispersion around point fermi surfaces, recently discovered in electronic structure calculations of vo $ _ 2 $ / tio $ _ 2 $ nano - heterostructures. we contrast their spectral properties with the well known dirac points on the honeycomb lattice relevant to graphene layers and the spectra of bands touching each other in zero - gap semiconductors. we also consider the lowest order dispersion around one of the semi - dirac points and calculate the resulting electronic energy levels in an external magnetic field. we find that these systems support apparently similar electronic structures but diverse low - energy physics.
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arxiv:0906.1564
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induction of thermal damage to tissue through delivery of microwave energy is frequently applied in surgery to destroy diseased tissue such as cancer cells. minimization of unwanted harm to healthy tissue is still achieved subjectively, and the surgeon has few tools at their disposal to monitor the spread of the induced damage. this work describes the use of optical methods to monitor the time course of changes to the tissue during delivery of microwave energy in the porcine liver. multispectral imaging and diffuse reflectance spectroscopy are used to monitor temporal changes in optical properties in parallel with thermal imaging. the results demonstrate the ability to monitor the spatial extent of thermal damage on a whole organ, including possible secondary effects due to vascular damage. future applications of this type of imaging may see the multispectral data used as a feedback mechanism to avoid collateral damage to critical healthy structures and to potentially verify sufficient application of energy to the diseased tissue.
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arxiv:1810.04337
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generating high - quality data ( e. g. images or video ) is one of the most exciting and challenging frontiers in unsupervised machine learning. utilizing quantum computers in such tasks to potentially enhance conventional machine learning algorithms has emerged as a promising application, but poses big challenges due to the limited number of qubits and the level of gate noise in available devices. in this work, we provide the first practical and experimental implementation of a quantum - classical generative algorithm capable of generating high - resolution images of handwritten digits with state - of - the - art gate - based quantum computers. in our quantum - assisted machine learning framework, we implement a quantum - circuit based generative model to learn and sample the prior distribution of a generative adversarial network. we introduce a multi - basis technique that leverages the unique possibility of measuring quantum states in different bases, hence enhancing the expressivity of the prior distribution. we train this hybrid algorithm on an ion - trap device based on $ ^ { 171 } $ yb $ ^ { + } $ ion qubits to generate high - quality images and quantitatively outperform comparable classical generative adversarial networks trained on the popular mnist data set for handwritten digits.
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arxiv:2012.03924
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deploying digital pathology models across medical centers is challenging due to distribution shifts. recent advances in domain generalization improve model transferability in terms of aggregated performance measured by the area under curve ( auc ). however, clinical regulations often require to control the transferability of other metrics, such as prescribed sensitivity levels. we introduce a novel approach to control the sensitivity of whole slide image ( wsi ) classification models, based on optimal transport and multiple instance learning ( mil ). validated across multiple cohorts and tasks, our method enables robust sensitivity control with only a handful of calibration samples, providing a practical solution for reliable deployment of computational pathology systems.
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arxiv:2502.20144
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the vast available spectrum in the millimeter wave ( mmwave ) bands offers the possibility of multi - gbps data rates for fifth generation ( 5g ) cellular networks. however, mmwave capacity can be highly intermittent due to the vulnerability of mmwave signals to blockages and delays in directional searching. such highly variable links present unique challenges for adaptive control mechanisms in transport layer protocols and end - to - end applications. this paper considers the fundamental question of whether tcp - the most widely used transport protocol - will work in mmwave cellular systems. the paper provides a comprehensive simulation study of tcp considering various factors such as the congestion control algorithm, including the recently proposed tcp bbr, edge vs. remote servers, handover and multi - connectivity, tcp packet size and 3gpp - stack parameters. we show that the performance of tcp on mmwave links is highly dependent on different combinations of these parameters, and identify the open challenges in this area.
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arxiv:1806.05783
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with the growing cyber - security threats, ensuring the security of data in cloud data centers is a challenging task. a prominent type of attack on cloud data centers is data tampering attack that can jeopardize the confidentiality and the integrity of data. in this article, we present a security and performance driven architecture for these centers that incorporates an intrusion management system for multi - tenant distributed transactional databases. the proposed architecture uses a novel data partitioning and placement scheme based on damage containment and communication cost of distributed transactions. in addition, we present a benchmarking framework for evaluating the performance of the proposed architecture. the results illustrate a trade - off between security and performance goals for cloud data centers.
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arxiv:2003.12598
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we reveal all linear order inertial and gravitational effects on a non - relativistic dirac particle ( mass $ m $ ) on the earth up to the order of $ 1 / m $ in the foldy - wouthuysen - like expansion. applying the result to penning trap experiments where a dirac particle experiences the cyclotron motion and the spin precession in a cavity, i. e., a geonium atom, we study modifications to the $ g $ - factor of such as the electron. it is shown that each correction from gravity has different dependence on the cyclotron frequency and the mass $ m $. therefore, their magnitude change depending on situations. in a particular case of an electron $ g $ - factor measurement, the dominant correction to the observed $ g $ - factor comes from effects of the earth ' s rotation, which is $ \ delta g / 2 \ simeq 5. 2 \ times 10 ^ { - 17 } $. it may be detectable in the near future.
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arxiv:2011.11217
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we present arecibo observations of psr b1534 + 12 which confirm previous suggestions that the pulse profile is evolving secularly. this effect is similar to that seen in psr b1913 + 16, and is almost certainly due to general relativistic precession of the pulsar ' s spin axis.
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arxiv:astro-ph/9911198
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two - dimensional ideal incompressible magnetohydrodynamic ( mhd ) linear waves at the surface of a rotating sphere are studied as a model to imitate the outermost layer of the earth ' s core or the solar tachocline. this thin conducting layer is permeated by a toroidal magnetic field the magnitude of which depends only on the latitude. the malkus background field, which is proportional to the sine of the colatitude, provides two well - known groups of branches ; on one branch, retrograde alfv \ ' en waves gradually become fast magnetic rossby ( mr ) waves as the field amplitude decreases, and on the other, prograde alfv \ ' en waves undergo a gradual transition into slow mr waves. in the case of non - malkus fields, we demonstrate that the associated eigenvalue problems can yield a continuous spectrum instead of alfv \ ' en and slow mr discrete modes. the critical latitudes attributed to the alfv \ ' en resonance eliminate these discrete eigenvalues and produce an infinite number of singular eigenmodes. the theory of slowly varying wave trains in an inhomogeneous magnetic field shows that a wave packet related to this continuous spectrum propagates toward a critical latitude corresponding to the wave and is eventually absorbed there. the expected behaviour whereby the retrograde propagating packets pertaining to the continuous spectrum approach the latitudes from the equatorial side and the prograde ones approach from the polar side is consistent with the profiles of their eigenfunctions derived using our numerical calculations. further in - depth discussions of the alfv \ ' en continuum would develop the theory of the ` ` wave - mean field interaction ' ' in the mhd system and the understanding of the dynamics in such thin layers.
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arxiv:2310.01341
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let $ x $ be a compact connected strongly pseudoconvex cr manifold of dimension $ 2n + 1, n \ ge 1 $ with a transversal cr $ s ^ 1 $ - action on $ x $. in this paper we introduce the quillen metric on the determinant line of the fourier components of the kohn - rossi cohomology on $ x $ with respect to the $ s ^ 1 $ - action. we study the behavior of the quillen metric under the change of the metrics on the manifold $ x $ and on the vector bundle over $ x $. we obtain an anomaly formula for the quillen metric on $ x $ with respect to the $ s ^ 1 $ - action.
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arxiv:1706.01078
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architectural technical debt ( atd ) is considered as the most significant type of td in industrial practice. in this study, we interview 21 software engineers and architects to investigate a specific type of atd, namely architectural smells ( as ). our goal is to understand the phenomenon of as better and support practitioners to better manage it and researchers to offer relevant support. the findings of this study provide insights on how practitioners perceive as and how they introduce them, the maintenance and evolution issues they experienced and associated to the presence of as, and what practices and tools they adopt to manage as.
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arxiv:2110.06750
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y cvn is a carbon star surrounded by a detached dust shell that has been imaged by the infrared space observatory at 90 microns. with the nancay radio telescope we have studied the gaseous counterpart in the 21 - cm hi emission line. new data have been acquired and allow to improve the signal to noise ratio on this line. the high spectral resolution line profiles obtained at the position of the star and at several offset positions set strong constraints on the gas temperature and kinematics within the detached shell ; the bulk of the material should be at ~ 100 - 200 k and in expansion at ~ 1 - 2 km / s. in addition, the line profile at the central position shows a quasi - rectangular pedestal that traces an 8 km / s outflow of ~ 1. 0 10 ^ - 7 msol / yr, stable for about 2 10 ^ 4 years, which corresponds to the central outflow already studied with co rotational lines. we present a model in which the detached shell results from the slowing - down of the stellar wind by surrounding matter. the inner radius corresponds to the location where the stellar outflow is abruptly slowed down from ~ 8 km / s to 2 km / s ( termination shock ). the outer radius corresponds to the location where external matter is compressed by the expanding shell ( bow shock ). in this model the mass loss rate of y cvn has been set constant, at the same level of 1. 0 10 ^ - 7 msol / yr, for ~ 4. 5 10 ^ 5 years. the gas temperature varies from ~ 1800 k at the inner limit to 165 k at the interface between circumstellar matter and external matter. our modelling shows that the presence of a detached shell around an agb star may not mean that a drastic reduction of the mass loss rate has occurred in the past. the inner radius of such a shell might only be the effect of a termination shock rather than of an interruption of the mass loss process.
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arxiv:0706.4211
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the families of bijective transformations $ g _ n $ of affine space $ k ^ n $ over general commutative ring $ k $ of increasing order with the property of stability will be constructed. stability means that maximal degree of elements of cyclic subgroup generated by the transformation of degree $ d $ is bounded by $ d $. in the case $ k = f _ q $ these transformations of $ k ^ n $ can be of an exponential order. we introduce large groups formed by quadratic transformations and numerical encryption algorithm protected by secure protocol of noncommutative cryptography. the construction of transformations is presented in terms of walks on double schubert graphs.
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arxiv:2108.08288
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the central idea of compressed sensing is to exploit the fact that most signals of interest are sparse in some domain and use this to reduce the number of measurements to encode. however, if the sparsity of the input signal is not precisely known, but known to lie within a specified range, compressed sensing as such cannot exploit this fact and would need to use the same number of measurements even for a very sparse signal. in this paper, we propose a novel method called compressed shattering to adapt compressed sensing to the specified sparsity range, without changing the sensing matrix by creating shattered signals which have fixed sparsity. this is accomplished by first suitably permuting the input spectrum and then using a filter bank to create fixed sparsity shattered signals. by ensuring that all the shattered signals are utmost 1 - sparse, we make use of a simple but efficient deterministic sensing matrix to yield very low number of measurements. for a discrete - time signal of length 1000, with a sparsity range of $ 5 - 25 $, traditional compressed sensing requires $ 175 $ measurements, whereas compressed shattering would only need $ 20 - 100 $ measurements.
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arxiv:1601.02200
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in this paper we study a variation of the accessibility percolation model, this is also motivated by evolutionary biology and evolutionary computation. consider a tree whose vertices are labeled with random numbers. we study the probability of having a monotone subsequence of a path from the root to a leaf, where any $ k $ consecutive vertices in the path contain at least one vertex of the subsequence. an $ n $ - ary tree, with height $ h $, is a tree whose vertices at distance at most $ h - 1 $ to the root have $ n $ children. for the case of $ n $ - ary trees, we prove that, as $ h $ tends to infinity the probability of having such subsequence : tends to 1, if $ n $ grows significantly faster than $ \ sqrt [ k ] { h / ( ek ) } $ ; and tends to 0, if $ n $ grows significantly slower than $ \ sqrt [ k ] { h / ( ek ) } $.
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arxiv:1712.04548
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explainable ai ( xai ) methods focus on explaining what a neural network has learned - in other words, identifying the features that are the most influential to the prediction. in this paper, we call them " distinguishing features ". however, whether a human can make sense of the generated explanation also depends on the perceptibility of these features to humans. to make sure an explanation is human - understandable, we argue that the capabilities of humans, constrained by the human visual system ( hvs ) and psychophysics, need to be taken into account. we propose the { \ em human perceptibility principle for xai }, stating that, to generate human - understandable explanations, neural networks should be steered towards focusing on human - understandable cues during training. we conduct a case study regarding the classification of real vs. fake face images, where many of the distinguishing features picked up by standard neural networks turn out not to be perceptible to humans. by applying the proposed principle, a neural network with human - understandable explanations is trained which, in a user study, is shown to better align with human intuition. this is likely to make the ai more trustworthy and opens the door to humans learning from machines. in the case study, we specifically investigate and analyze the behaviour of the human - imperceptible high spatial frequency features in neural networks and xai methods.
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arxiv:2104.07954
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the temperature dependence of the magnetic resonance spectra of nitrogen - vacancy ( nv - ) ensembles in the range of 280 - 330 k was studied. four samples prepared under different conditions were studied with nv - concentrations ranging from 10 ppb to 15 ppm. for all of these samples, the axial zero - field splitting ( zfs ) parameter, d, was found to vary significantly with temperature, t, as dd / dt = - 74. 2 ( 7 ) khz / k. the transverse zfs parameter, e, was non - zero ( between 4 and 11 mhz ) in all samples, and exhibited a temperature dependence of de / ( edt ) = - 1. 4 ( 3 ) x 10 ^ ( - 4 ) k ^ ( - 1 ). the results might be accounted for by considering local thermal expansion. the observation of the temperature dependence of the zfs parameters presents a significant challenge for room - temperature diamond magnetometers and may ultimately limit their bandwidth and sensitivity.
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arxiv:0911.3938
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we prove the stability in weighted $ w ^ { 1, 1 } $ spaces for standard finite element approximations of the poisson equation in convex polygonal or polyhedral domains, when the weight belongs to muckenhoupt ' s class $ a _ 1 $ and the family of meshes is quasi - uniform.
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arxiv:2403.07934
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a monte carlo simulation study of the vacancy - assisted domain - growth in asymmetric binary alloys is presented. the system is modeled using a three - state abv hamiltonian which includes an asymmetry term, not considered in previous works. our simulated system is a stoichiometric two - dimensional binary alloy with a single vacancy which evolves according to the vacancy - atom exchange mechanism. we obtain that, compared to the symmetric case, the ordering process slows down dramatically. concerning the asymptotic behavior it is algebraic and characterized by the allen - cahn growth exponent x = 1 / 2. the late stages of the evolution are preceded by a transient regime strongly affected by both the temperature and the degree of asymmetry of the alloy. the results are discussed and compared to those obtained for the symmetric case.
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arxiv:cond-mat/9905163
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( abridged ) the violent hierarchical nature of the lcdm cosmology poses serious difficulties for the formation of disk galaxies. to help resolve these issues, we describe a new, merger - driven scenario for the cosmological formation of disk galaxies at high redshifts that supplements the standard model based on dissipational collapse. in this picture, large gaseous disks may be produced from high - angular momentum mergers of systems that are gas - dominated, i. e. m _ gas / ( m _ gas + m _ star > 0. 5 at the height of the merger. pressurization from the multiphase structure of the interstellar medium prevents the complete conversion of gas into stars during the merger, and if enough gas remains to form a disk, the remnant eventually resembles a disk galaxy. we perform numerical simulations of galaxy mergers to study how supernovae feedback strength, supermassive black hole growth and feedback, progenitor gas fraction, merger mass - ratio, and orbital geometry impact the formation of remnant disks. we find that disks can build angular momentum through mergers and the degree of rotational support of the baryons in the merger remnant is primarily related to feedback processes associated with star formation. disk - dominated remnants are restricted to form in mergers that are gas - dominated at the time of final coalescence and gas - dominated mergers typically require extreme progenitor gas fractions ( > 80 % ). we also show that the formation of rotationally - supported stellar systems in mergers is not restricted to idealized orbits, or major or minor mergers. we suggest that the hierarchical nature of the lcdm cosmology and the physics of the interstellar gas may act together to form spiral galaxies by building the angular momentum of disks through early, gas - dominated mergers.
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arxiv:astro-ph/0503369
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in this work we discuss the neutrino mass dependent nuclear matrix element ( nme ) of the neutrinoless double beta decay process and derive the limit on the parameter space of the minimal type - i seesaw model from the current available experimental data as well as the future sensitivities from the next - generation experiments. both the explicit many - body calculations and naive extrapolations of the mass dependent nme are employed in the current work. the uncertainties of the theoretical nuclear structure models are taken into account. by combining the latest experimental data from $ ^ { 76 } $ ge - based experiments, gerda and majorana, the $ ^ { 130 } $ te - based experiment, cuore and the $ ^ { 136 } $ xe - based experiments, kamland - zen and exo - 200, the bounds on the parameter space of the minimal type - i seesaw model are obtained and compared with the limits from other experimental probes. sensitivities for future experiments utilizing $ ^ { 76 } $ ge - based ( legend - 1000 ), $ ^ { 82 } $ se - based ( supernemo ), $ ^ { 130 } $ te based ( sno + ii ) and $ ^ { 136 } $ xe - based ( nexo ), with a ten - year exposure, are also derived.
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arxiv:2404.12316
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we study relative cohn path algebras, also known as leavitt - cohn path algebras, and we realize them as partial skew group rings ( to do this we prove uniqueness theorems for relative cohn path algebras ). furthermore, given any graph $ e $ we define $ e $ - relative branching systems and prove how they induce representations of the associated relative cohn path algebra. we give necessary and sufficient conditions for faithfulness of the representations associated to $ e $ - relative branching systems ( this improves previous results known to leavitt path algebras of row - finite graphs with no sinks ). to prove this last result we show first a version, for relative cohn - path algebras, of the reduction theorem for leavitt path algebras.
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arxiv:1806.03077
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adapter - based parameter - efficient transfer learning has achieved exciting results in vision - language models. traditional adapter methods often require training or fine - tuning, facing challenges such as insufficient samples or resource limitations. while some methods overcome the need for training by leveraging image modality cache and retrieval, they overlook the text modality ' s importance and cross - modal cues for the efficient adaptation of parameters in visual - language models. this work introduces a cross - modal parameter - efficient approach named xmadapter. xmadapter establishes cache models for both text and image modalities. it then leverages retrieval through visual - language bimodal information to gather clues for inference. by dynamically adjusting the affinity ratio, it achieves cross - modal fusion, decoupling different modal similarities to assess their respective contributions. additionally, it explores hard samples based on differences in cross - modal affinity and enhances model performance through adaptive adjustment of sample learning intensity. extensive experimental results on benchmark datasets demonstrate that xmadapter outperforms previous adapter - based methods significantly regarding accuracy, generalization, and efficiency.
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arxiv:2404.12588
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we investigate the formation and stability of a pair of identical soft capsules in channel flow under mild inertia. we employ a combination of the lattice boltzmann, finite element and immersed boundary methods to simulate the elastic particles in flow. validation tests show excellent agreement with numerical results obtained by other research groups. our results reveal new trajectory types that have not been observed for pairs of rigid particles. while particle softness increases the likelihood of a stable pair forming, the pair stability is determined by the lateral position of the particles. a key finding is that stabilisation of the axial distance occurs after lateral migration of the particles. during the later phase of pair formation, particles undergo damped oscillations that are independent of initial conditions. these damped oscillations are driven by a strong hydrodynamic coupling of the particle dynamics, particle inertia and viscous dissipation. while the frequency and damping coefficient of the oscillations depend on particle softness, the pair formation time is largely determined by the initial particle positions : the time to form a stable pair grows exponentially with the initial axial distance. our results demonstrate that particle softness has a strong impact on the behaviour of particle pairs. the findings could have significant ramifications for microfluidic applications where a constant and reliable axial distance between particles is required, such as flow cytometry.
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arxiv:2108.05277
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cooperation can be supported by indirect reciprocity via reputation. thanks to gossip, reputations are built and circulated and humans can identify defectors and ostracise them. however, the evolutionary stability of gossip is allegedly undermined by the fact that it is more error - prone that direct observation, whereas ostracism could be ineffective if the partner selection mechanism is not robust. the aim of this work is to investigate the conditions under which the combination of gossip and ostracism might support cooperation in groups of different sizes. we are also interested in exploring the extent to which errors in transmission might undermine the reliability of gossip as a mechanism for identifying defectors. our results show that a large quantity of gossip is necessary to support cooperation, and that group structure can mitigate the effects of errors in transmission.
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arxiv:1606.01711
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in this paper, we classify groups which faithfully act on smooth cubic threefolds. it turns out that there are exactly $ 6 $ maximal ones and we describe them with explicit examples of target cubic threefolds.
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arxiv:1907.00392
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recent nmr experiments on $ yba _ 2 ( cu _ { 1 - x } ni _ x ) _ 3o _ { 6 + \ delta } $ ( bobroff et al. phys. rev. lett. 79, 2117 ( 1997 ) ) have shown that ni impurities provide an important probe for the momentum dependence of the static spin susceptibility $ \ chi ' ( q ) $. combining the measurements of the $ ^ { 17 } $ o line width $ \ delta \ nu $ with those of the gaussian relaxation time $ t _ { 2g } $, we find that the magnetic correlation length $ \ xi $ must have a substantial temperature dependence. using numerical simulations we present a detailed analysis of $ \ delta \ nu $ as a function of temperature and impurity concentration. for a lorentzian shape of $ \ chi ' ( q ) $ $ \ delta \ nu $ strongly depends on $ \ xi $, in contrast to the gaussian form. this result together with the experimental finding that $ \ xi $ is temperature dependent rules out the gaussian form of $ \ chi ' ( q ) $.
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arxiv:cond-mat/9801317
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fully homomorphic encryption ( fhe ) is a promising cryptographic primitive for realizing private neural network inference ( pi ) services by allowing a client to fully offload the inference task to a cloud server while keeping the client data oblivious to the server. this work proposes neujeans, an fhe - based solution for the pi of deep convolutional neural networks ( cnns ). neujeans tackles the critical problem of the enormous computational cost for the fhe evaluation of cnns. we introduce a novel encoding method called coefficients - in - slot ( cins ) encoding, which enables multiple convolutions in one he multiplication without costly slot permutations. we further observe that cins encoding is obtained by conducting the first several steps of the discrete fourier transform ( dft ) on a ciphertext in conventional slot encoding. this property enables us to save the conversion between cins and slot encodings as bootstrapping a ciphertext starts with dft. exploiting this, we devise optimized execution flows for various two - dimensional convolution ( conv2d ) operations and apply them to end - to - end cnn implementations. neujeans accelerates the performance of conv2d - activation sequences by up to 5. 68 times compared to state - of - the - art fhe - based pi work and performs the pi of a cnn at the scale of imagenet within a mere few seconds.
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arxiv:2312.04356
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we study implications of the dynamical and spatial contact structure between brazilian escorts and sex - buyers for the spreading of sexually transmitted infections ( sti ). despite a highly skewed degree distribution diseases spreading in this contact structure have rather well - defined epidemic thresholds. temporal effects create a broad distribution of outbreak sizes even if the transmission probability is taken to the hypothetical value of 100 %. temporal correlations speed up outbreaks, especially in the early phase, compared to randomized contact structures. the time - ordering and the network topology, on the other hand, slow down the epidemics. studying compartmental models we show that the contact structure can probably not support the spread of hiv, not even if individuals were sexually active during the acute infection. we investigate hypothetical means of containing an outbreak and find that travel restrictions are about as efficient as removal of the vertices of highest degree. in general, the type of commercial sex we study seems not like a major factor in sti epidemics.
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arxiv:1006.2856
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we propose a simple and new unified method to achieve lag, complete and anticipatory synchronizations in coupled nonlinear systems. it can be considered as an alternative to the subsystem and intentional parameter mismatch methods. this novel method is illustrated in a unidirectionally coupled rc phase shift network based chua ' s circuit. employing feedback coupling, different types of chaos synchronization are observed experimentally and numerically in coupled identical chaotic oscillators { \ emph { without using time delay } }. with a simple switch in the experimental set up we observe different kinds of synchronization. we also analyze the coupled system with numerical simulations.
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arxiv:1603.06250
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we prove microlocal estimates with normally hyperbolic trapping. we use a new type of symbol class which is constructed by blowing up the intersection of the unstable manifold and the fiber infinity. for scalar wave equations on kerr ( - de sitter ) spacetimes, the extra loss of the microlocal estimates compared with the standard propagation of singularities is arbitrarily small.
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arxiv:2206.04820
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inhomogeneous metasurfaces have shown possibilities for unprecedented control of wave propagation and scattering. while it is conventional to shine a single incident plane wave from one side of these metastructures, illuminating by several waves simultaneously from both sides may enhance possibilities to control scattered waves, which results in additional functionalities and novel applications. here, we unveil how using coherent plane - wave illumination of a properly designed inhomogeneous metasurface sheet it is possible to realize controllable retroreflection. we call these metasurfaces as " coherent retroreflectors " and explain the method for realizing them both in theory and practice. we show that coherent retroreflectors can be used for filtering undesired modes and creation of field - localization regions in waveguides. the latter application is in resemblance to bound states in the radiation continuum.
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arxiv:2012.14391
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