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we focus on a question raised by daws [ arens regularity of the algebra of operators on a banach space, bull. lond. math. soc. 36 ( 2004 ), 493 - 503 ] concerning the arens regularity of b ( x ), the algebra of operators on a banach space x. among other things, we show that b ( x ) is arens regular if and only if x is ultrareflexive.
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arxiv:1608.05986
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the risk estimator called " direct eigenvalue estimator " ( dee ) is studied. dee was developed for small sample regression. in contrast to many existing model selection criteria, derivation of dee requires neither any asymptotic assumption nor any prior knowledge about the noise variance and the noise distribution. it was reported that dee performed well in small sample cases but dee performed a little worse than the state - of - the - art adj. this seems somewhat counter - intuitive because dee was developed for specifically regression problem by exploiting available information exhaustively, while adj was developed for general setting. in this paper, we point out that the derivation of dee includes an inappropriate part in spite that the resultant form of dee is valid in a sense. as its result, dee cannot derive its potential. we introduce a class of valid risk estimators based on the idea of dee and show that better risk estimators ( mdee ) can be found in the class. by numerical experiments, we verify that mdee often performs better than or at least equally the original dee and adj.
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arxiv:1610.03938
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we propose defect extremal surface as the holographic counterpart of boundary quantum extremal surface. the defect extremal surface is defined by minimizing the ryu - takayanagi surface corrected by the defect theory. this is particularly interesting when the rt surface crosses or terminates on the defect. in a simple set up of ads / bcft, we find that the defect extremal surface formula gives precisely the same results of the boundary quantum extremal surface. we provide a decomposition procedure of an ads bulk with a defect brane to see clearly how island formula emerges from a brane world system with gravity glued to a flat space quantum field theory.
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arxiv:2012.07612
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the assouad dimension of the limit set of a geometrically finite kleinian group with parabolics may exceed the hausdorff and box dimensions. the assouad \ emph { spectrum } is a continuously parametrised family of dimensions which ` interpolates ' between the box and assouad dimensions of a fractal set. it is designed to reveal more subtle geometric information than the box and assouad dimensions considered in isolation. we conduct a detailed analysis of the assouad spectrum of limit sets of geometrically finite kleinian groups and the associated patterson - sullivan measure. our analysis reveals several novel features, such as interplay between horoballs of different rank not seen by the box or assouad dimensions.
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arxiv:2203.04931
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we propose a new method for identifying active galactic nuclei ( agn ) in low mass ( $ \ rm m _ * \ leq10 ^ { 10 } m _ \ odot $ ) galaxies. this method relies on spectral energy distribution ( sed ) fitting to identify galaxies whose radio flux density has an excess over that expected from star formation alone. combining data in the galaxy and mass assembly ( gama ) g23 region from gama, evolutionary map of the universe ( emu ) early science observations, and wide - field infrared survey explorer ( wise ), we compare this technique with a selection of different agn diagnostics to explore the similarities and differences in agn classification. we find that diagnostics based on optical and near - infrared criteria ( the standard bpt diagram, the wise colour criterion, and the mass - excitation, or mex diagram ) tend to favour detection of agn in high mass, high luminosity systems, while the ` ` prospect ' ' sed fitting tool can identify agn efficiently in low mass systems. we investigate an explanation for this result in the context of proportionally lower mass black holes in lower mass galaxies compared to higher mass galaxies and differing proportions of emission from agn and star formation dominating the light at optical and infrared wavelengths as a function of galaxy stellar mass. we conclude that sed - derived agn classification is an efficient approach to identify low mass hosts with low radio luminosity agn.
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arxiv:2402.11817
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the superfluid density near the superconducting transition is investigated in the presence of spatial inhomogeneity in the critical temperature. disorder is accounted for by means of a random $ t _ c $ term in the conventional ginzburg - landau action for the superconducting order parameter. focusing on the case where a low - density of randomly distributed planar defects are responsible for the variation of $ t _ c $, we derive the lowest order correction to the superfluid density in powers of the defect concentration. the correction is calculated assuming a broad gaussian distribution for the strengths of the defect potentials. our results are in a qualitative agreement with the superfluid density measurements in the underdoped regime of high - quality ybco crystals by broun and co - workers.
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arxiv:0808.1314
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quantum metrology research promises approaches to build new sensors that achieve the ultimate level of precision measurement and perform fundamentally better than modern sensors. practical schemes that tolerate realistic fabrication imperfections and environmental noise are required in order to realise quantum - enhanced sensors and to enable their real - world application. we have demonstrated the key enabling principles of a practical, loss - tolerant approach to photonic quantum metrology designed to harness all multi - photon components in spontaneous parametric downconversion - - - a method for generating multiple photons that we show requires no further fundamental state engineering for use in practical quantum metrology. we observe a quantum advantage of 28 % in precision measurement of optical phase using the four - photon detection component of this scheme, despite 83 % system loss. this opens the way to new quantum sensors based on current quantum - optical capabilities.
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arxiv:1307.4673
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we discuss the energy of the excited 2 $ ^ + $ state in the unbound nucleus $ ^ { 26 } $ o using the three - body model of $ ^ { 24 } $ o + $ n $ + $ n $. this model fully takes into account the continuum effects as well as the dineutron correlation of the valence neutrons. the present calculation yields the energy of 1. 354 mev, which is slightly smaller than the unperturbed energy, 1. 54 mev. the energy shifts for the ground and the 2 $ ^ + $ states with respect to the unperturbed energy suggest that 0 $ ^ + $ and the 2 $ ^ + $ states in $ ^ { 26 } $ o show a typical spectrum well described by a short - range pairing interaction acting on two valence nucleons in the same orbit.
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arxiv:1407.3560
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we investigate the taylor expansion of the baryon number susceptibility, and hence, pressure, in a series in the baryon chemical potential ( mu _ b ) through a lattice simulation with light dynamical staggered quarks at a finer lattice cutoff a = 1 / 6t. we determine the qcd cross over coupling at mu _ b = 0. we find the radius of convergence of the series at various temeperatures, and bound the location of the qcd critical point to be t ^ e / t _ c = 0. 94 and mu _ b ^ e / t < 1. 8. we also investigate the extrapolation of various susceptibilities and linkages to finite chemical potential.
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arxiv:0806.2233
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given a symmetric siegel domain $ \ mathscr d $ and a positive plurihamonic function $ f $ on $ \ mathscr d $, we study the largest positive radon measure $ \ mu $ on the silov boundary $ \ mathrm b \ mathscr d $ of $ \ mathscr d $ whose poisson integral $ \ mathscr p \ mu $ is $ \ leq f $. if $ \ mathscr d $ has no tubular irreducible factors of rank $ \ geq 2 $, we show that $ \ mathscr p \ mu $ is plurihamonic, and that $ f - \ mathscr p \ mu $ is linear. as an application, we describe a possible analogue of the family of clark measures associated with a holomorphic function from $ \ mathscr d $ into the unit disc in $ \ mathbb c $.
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arxiv:2403.05436
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we study radio - frequency ( rf ) wireless power transfer ( wpt ) using a digital radio transmitter for applications where alternative analog transmit circuits are impractical. an important paramter for assessing the viability of an rf wpt system is its end - to - end efficiency. in this regard, we present a prototype test - bed comprising a software - defined radio ( sdr ) transmitter and an energy harvesting receiver with a low resistive load ; employing an sdr makes our research meaningful for simultaneous wireless information and power transfer ( swipt ). we analyze the effect of clipping and non - linear amplification at the sdr on multisine waveforms. our experiments suggest that when the dc input power at the transmitter is constant, high peak - to - average power ratio ( papr ) multisine are unsuitable for rf wpt over a flat - fading channel, due to their low average radiated power. the results indicate that the end - to - end efficiency is positively correlated to the average rf power of the waveform, and that it reduces with increasing papr. consequently, digital modulations such as phase - shift keying ( psk ) and quadrature amplitude modeulation ( qam ) yield better end - to - end efficiency than multisines. moreover, the end - to - end efficiency of psk and qam signals is invariant of the transmission bit rate. an in - depth analysis of the end - to - end efficiency of wpt reveals that the transmitter efficiency is lower than the receiver efficiency. furthermore, we study the impact of a reflecting surface on the end - to - end efficiency of wpt, and assess the transmission quality of the information signals by evaluating their error vector magnitude ( evm ) for swipt. overall, the experimental observations of end - to - end efficiency and evm suggest that, while employing an sdr transmitter with fixed dc input power, a baseband quadrature psk signal is most suitable for swipt at large, among psk and qam signals.
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arxiv:2012.01108
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we analyze the role of the difference between the central frequencies of the spectral distributions of the vector potential and the electric field of a short laser pulse. the frequency shift arises when the electric field is determined as the derivative of the vector potential to ensure that both quantities vanish at the beginning and end of the pulse. we derive an analytical estimate of the frequency shift and show how it affects various light induced processes, such as excitation, ionization and high harmonic generation. since observables depend on the frequency spectrum of the electric field, the shift should be taken into account when setting the central frequency of the vector potential to avoid potential misinterpretation of numerical results for processes induced by few - cycle pulses.
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arxiv:1807.00856
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in this paper, we demonstrate some applications of compressive sensing over networks. we make a connection between compressive sensing and traditional information theoretic techniques in source coding and channel coding. our results provide an explicit trade - off between the rate and the decoding complexity. the key difference of compressive sensing and traditional information theoretic approaches is at their decoding side. although optimal decoders to recover the original signal, compressed by source coding have high complexity, the compressive sensing decoder is a linear or convex optimization. first, we investigate applications of compressive sensing on distributed compression of correlated sources. here, by using compressive sensing, we propose a compression scheme for a family of correlated sources with a modularized decoder, providing a trade - off between the compression rate and the decoding complexity. we call this scheme sparse distributed compression. we use this compression scheme for a general multicast network with correlated sources. here, we first decode some of the sources by a network decoding technique and then, we use a compressive sensing decoder to obtain the whole sources. then, we investigate applications of compressive sensing on channel coding. we propose a coding scheme that combines compressive sensing and random channel coding for a high - snr point - to - point gaussian channel. we call this scheme sparse channel coding. we propose a modularized decoder providing a trade - off between the capacity loss and the decoding complexity. at the receiver side, first, we use a compressive sensing decoder on a noisy signal to obtain a noisy estimate of the original signal and then, we apply a traditional channel coding decoder to find the original signal.
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arxiv:1012.0955
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the pre - exponential factor in the probability of decay of a metastable vacuum is calculated for a generic ( 2 + 1 ) dimensional model in the limit of small difference $ \ epsilon $ of the energy density between the metastable and the stable vacua. it is shown that this factor is proportional to $ \ epsilon ^ { - 7 / 3 } $ and that the power does not depend on details of the underlying field theory. the calculation is done by using the effective lagrangian method for the relevant soft ( goldstone ) degrees of freedom in the problem. unlike in the ( 1 + 1 ) dimensional case, where the decay rate is completely determined by the parameters of the effective lagrangian and is thus insensitive to the specific details of the underlying ( microscopic ) theory, in the considered here ( 2 + 1 ) dimensional case the pre - exponential factor is found up to a constant, which does depend on specifics of the underlying short - distance dynamics, but does not depend on the energy asymmetry parameter $ \ epsilon $. thus the functional dependence of the decay rate on $ \ epsilon $ is universally determined in the considered limit of small $ \ epsilon $.
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arxiv:hep-th/0407061
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the problem of structure from motion is concerned with recovering 3 - dimensional structure of an object from a set of 2 - dimensional images. generally, all information can be uniquely recovered if enough images and image points are provided, but there are certain cases where unique recovery is impossible ; these are called critical configurations. in this paper we use an algebraic approach to study the critical configurations for two projective cameras. we show that all critical configurations lie on quadric surfaces, and classify exactly which quadrics constitute a critical configuration. the paper also describes the relation between the different reconstructions when unique reconstruction is impossible.
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arxiv:2112.05074
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recent advances in ai technology have made the forgery of digital images and videos easier, and it has become significantly more difficult to identify such forgeries. these forgeries, if disseminated with malicious intent, can negatively impact social and political stability, and pose significant ethical and legal challenges as well. deepfake is a variant of auto - encoders that use deep learning techniques to identify and exchange images of a person ' s face in a picture or film. deepfake can result in an erosion of public trust in digital images and videos, which has far - reaching effects on political and social stability. this study therefore proposes a solution for facial forgery detection to determine if a picture or film has ever been processed by deepfake. the proposed solution reaches detection efficiency by using the recently proposed separable convolutional neural network ( cnn ) and image segmentation. in addition, this study also examined how different image segmentation methods affect detection results. finally, the ensemble model is used to improve detection capabilities. experiment results demonstrated the excellent performance of the proposed solution.
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arxiv:1912.12184
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we present a topological framework for finding low - flop algorithms for evaluating element stiffness matrices associated with multilinear forms for finite element methods posed over straight - sided affine domains. this framework relies on phrasing the computation on each element as the contraction of each collection of reference element tensors with an element - specific geometric tensor. we then present a new concept of complexity - reducing relations that serve as distance relations between these reference element tensors. this notion sets up a graph - theoretic context in which we may find an optimized algorithm by computing a minimum spanning tree. we present experimental results for some common multilinear forms showing significant reductions in operation count and also discuss some efficient algorithms for building the graph we use for the optimization.
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arxiv:1205.3001
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persistent homology is a tool that can be employed to summarize the shape of data by quantifying homological features. when the data is an object in $ \ mathbb { r } ^ d $, the ( augmented ) persistent homology transform ( ( a ) pht ) is a family of persistence diagrams, parameterized by directions in the ambient space. a recent advance in understanding the pht used the framework of reconstruction in order to find finite a set of directions to faithfully represent the shape, a result that is of both theoretical and practical interest. in this paper, we improve upon this result and present an improved algorithm for graph - - and, more generally one - skeleton - - reconstruction. the improvement comes in reconstructing the edges, where we use a radial binary ( multi - ) search. the binary search employed takes advantage of the fact that the edges can be ordered radially with respect to a reference plane, a feature unique to graphs.
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arxiv:2212.13206
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in this note, we give a short proof of the torelli theorem for cubic fourfolds that relies on the global torelli theorem for irreducible holomorphic symplectic varieties proved by verbitsky.
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arxiv:1209.4509
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in this paper, we consider the dynamic multi - robot distribution problem where a heterogeneous group of networked robots is tasked to spread out and simultaneously move towards multiple moving task areas while maintaining connectivity. the heterogeneity of the system is characterized by various categories of units and each robot carries different numbers of units per category representing heterogeneous capabilities. every task area with different importance demands a total number of units contributed by all of the robots within its area. moreover, we assume the importance and the total number of units requested from each task area is initially unknown. the robots need first to explore, i. e., reach those areas, and then be allocated to the tasks so to fulfill the requirements. the multi - robot distribution problem is formulated as designing controllers to distribute the robots that maximize the overall task fulfillment while minimizing the traveling costs in presence of connectivity constraints. we propose a novel connectivity - aware multi - robot redistribution approach that accounts for dynamic task allocation and connectivity maintenance for a heterogeneous robot team. such an approach could generate sub - optimal robot controllers so that the amount of total unfulfilled requirements of the tasks weighted by their importance is minimized and robots stay connected at all times. simulation and numerical results are provided to demonstrate the effectiveness of the proposed approaches.
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arxiv:2012.10008
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we give a detailed account of the methods introduced in [ 1 ] to calculate holographic four - point correlators in iib supergravity on $ ads _ 5 \ times s ^ 5 $. our approach relies entirely on general consistency conditions and maximal supersymmetry. we discuss two related methods, one in position space and the other in mellin space. the position space method is based on the observation that the holographic four - point correlators of one - half bps single - trace operators can be written as finite sums of contact witten diagrams. we demonstrate in several examples that imposing the superconformal ward identity is sufficient to fix the parameters of this ansatz uniquely, avoiding the need for a detailed knowledge of the supergravity effective action. the mellin space approach is an " on - shell method " inspired by the close analogy between holographic correlators and flat space scattering amplitudes. we conjecture a compact formula for the four - point correlators of one - half bps single - trace operators of arbitrary weights. our general formula has the expected analytic structure, obeys the superconformal ward identity, satisfies the appropriate asymptotic conditions and reproduces all the previously calculated cases. we believe that these conditions determine it uniquely.
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arxiv:1710.05923
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multiple description coding ( mdc ) is an error - resilient source coding method designed for transmission over noisy channels. we present a novel mdc scheme employing a neural network based on implicit neural representation. this involves overfitting the neural representation for images. each description is transmitted along with model parameters and its respective latent spaces. our method has advantages over traditional mdc that utilizes auto - encoders, such as eliminating the need for model training and offering high flexibility in redundancy adjustment. experiments demonstrate that our solution is competitive with autoencoder - based mdc and classic mdc based on hevc, delivering superior visual quality.
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arxiv:2306.13919
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we report neutron scattering measurements of the spectrum of magnetic excitations in the stripe - ordered phase of la2 - xsrxnio4 ( x = 0. 275 and 1 / 3 ). the propagating spin excitations follow a similar dispersion relation for the two compositions, but the line widths are broader for x = 0. 275 than for x = 1 / 3.
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arxiv:cond-mat/0308630
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we propose a class of e6 - based local orbifold grand unified theories ( guts ) which yield an exceptional supersymmetric standard model as their low energy theory including leptoquark and unhiggs exotics and a z ' at the tev scale. unification is achieved in two steps through an intermediate scale symmetry breaking.
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arxiv:1001.4074
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let $ g $ be a finite abelian group, let $ 0 < \ alpha < 1 $, and let $ a \ subseteq g $ be a random set of size $ | g | ^ \ alpha $. we let $ $ \ mu ( a ) = \ max _ { b, c : | b | = | c | = | a | } | \ { ( a, b, c ) \ in a \ times b \ times c : a = b + c \ } |. $ $ the issue is to determine upper bounds on $ \ mu ( a ) $ that hold with high probability over the random choice of $ a $. mennink and preneel \ cite { bm } conjecture that $ \ mu ( a ) $ should be close to $ | a | $ ( up to possible logarithmic factors in $ | g | $ ) for $ \ alpha \ leq 1 / 2 $ and that $ \ mu ( a ) $ should not much exceed $ | a | ^ { 3 / 2 } $ for $ \ alpha \ leq 2 / 3 $. we prove the second half of this conjecture by showing that $ $ \ mu ( a ) \ leq | a | ^ 3 / | g | + 4 | a | ^ { 3 / 2 } \ ln ( | g | ) ^ { 1 / 2 } $ $ with high probability, for all $ 0 < \ alpha < 1 $. we note that $ 3 \ alpha - 1 \ leq ( 3 / 2 ) \ alpha $ for $ \ alpha \ leq 2 / 3 $. in previous work, alon et al $. $ have shown that $ \ mu ( a ) \ leq o ( 1 ) | a | ^ 3 / | g | $ with high probability for $ \ alpha \ geq 2 / 3 $ while kiltz, pietrzak and szegedy show that $ \ mu ( a ) \ leq | a | ^ { 1 + 2 \ alpha } $ with high probability for $ \ alpha \ leq 1 / 4 $. current bounds on $ \ mu ( a ) $ are essentially sharp for the range $ 2 / 3 \ leq \ alpha \ leq 1 $. finding better bounds remains an open problem for the range $ 0 < \ alpha < 2 / 3 $ and especially for the range $ 1 / 4 < \ alpha < 2 / 3 $ in which the bound of kiltz
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arxiv:1309.5582
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$ f $ the germ of $ f $ at $ z $ is smoothly equivalent to a homogeneous polynomial $ \ mathbb { r } ^ 2 \ to \ mathbb { r } $ without multiple linear factors.
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arxiv:1610.01219
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the article [ hps ] established a monotonicity inequality for the helmholtz equation and presented applications to shape detection and local uniqueness in inverse boundary problems. the monotonicity inequality states that if two scattering coefficients satisfy $ q _ 1 \ leq q _ 2 $, then the corresponding neumann - to - dirichlet operators satisfy $ \ lambda ( q _ 1 ) \ leq \ lambda ( q _ 2 ) $ up to a finite dimensional subspace. here we improve the bounds for the dimension of this space. in particular, if $ q _ 1 $ and $ q _ 2 $ have the same number of positive neumann eigenvalues, then the finite dimensional space is trivial.
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arxiv:1901.08495
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we introduce a just - in - time runtime program transformation strategy based on repeated recursion unfolding. our online program optimization generates several versions of a recursion differentiated by the minimal number of recursive steps covered. the base case of the recursion is ignored in our technique. our method is introduced here on the basis of single linear direct recursive rules. when a recursive call is encountered at runtime, first an unfolder creates specializations of the associated recursive rule on - the - fly and then an interpreter applies these rules to the call. our approach reduces the number of recursive rule applications to its logarithm at the expense of introducing a logarithmic number of generic unfolded rules. we prove correctness of our online optimization technique and determine its time complexity. for recursions which have enough simplifyable unfoldings, a super - linear is possible, i. e. speedup by more than a constant factor. the necessary simplification is problem - specific and has to be provided at compile - time. in our speedup analysis, we prove a sufficient condition as well as a sufficient and necessary condition for super - linear speedup relating the complexity of the recursive steps of the original rule and the unfolded rules. we have implemented an unfolder and meta - interpreter for runtime repeated recursion unfolding with just five rules in constraint handling rules ( chr ) embedded in prolog. we illustrate the feasibility of our approach with simplifications, time complexity results and benchmarks for some basic tractable algorithms. the simplifications require some insight and were derived manually. the runtime improvement quickly reaches several orders of magnitude, consistent with the super - linear speedup predicted by our theorems.
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arxiv:2307.02180
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we have observed centaurus a with the mid - infrared interferometric instrument ( midi ) at the very large telescope interferometer ( vlti ) at resolutions of 7 - 15 mas ( at 12. 5 micron ) and filled gaps in the ( u, v ) coverage in comparison to earlier measurements. we are now able to describe the nuclear emission in terms of geometric components and derive their parameters by fitting models to the interferometric data. with simple geometrical models, the best fit is achieved for an elongated disk with flat intensity profile with diameter 76 + / - 9 mas x 35 + / - 2 mas ( 1. 41 + / - 0. 17 pc x 0. 65 + / - 0. 03 pc ) whose major axis is oriented at a position angle ( pa ) of 10. 1 + / - 2. 2 degrees east of north. a point source contributes 47 + / - 11 % of the nuclear emission at 12. 5 micron. there is also evidence that neither such a uniform nor a gaussian disk are good fits to the data. this indicates that we are resolving more complicated small - scale structure in agns with midi, as has been seen in seyfert galaxies previously observed with midi. the pa and inferred inclination i = 62. 6 + 2. 1 / - 2. 6 degrees of the dust emission are compared with observations of gas and dust at larger scales.
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arxiv:1008.0858
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artificial bee colony ( abc ), an optimization algorithm is a recent addition to the family of population based search algorithm. abc has taken its inspiration from the collective intelligent foraging behavior of honey bees. in this study we have incorporated golden section search mechanism in the structure of basic abc to improve the global convergence and prevent to stick on a local solution. the proposed variant is termed as ils - abc. comparative numerical results with the state - of - art algorithms show the performance of the proposal when applied to the set of unconstrained engineering design problems. the simulated results show that the proposed variant can be successfully applied to solve real life problems.
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arxiv:1210.6128
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we analyze the shape of radial second dirichlet eigenfunctions of fractional schr \ " odinger type operators of the form $ ( - \ delta ) ^ s + v $ in the unit ball $ b $ in $ \ mathbb { r } ^ n $ with a nondecreasing radial potential $ v $. specifically, we show that the eigenspace corresponding to the second radial eigenvalue is simple and spanned by an eigenfunction $ u $ which changes sign precisely once in the radial variable and does not have zeroes anywhere else in $ b $. moreover, by a new hopf type lemma for supersolutions to a class of degenerate mixed boundary value problems, we show that $ u $ has a nonvanishing fractional boundary derivative on $ \ partial b $. we apply this result to prove uniqueness and nondegeneracy of positive ground state solutions to the problem $ ( - \ delta ) ^ s u + \ lambda u = u ^ p $ on $ { b } $, $ \ ; u = 0 $ on $ \ mathbb { r } ^ n \ setminus b $. here $ s \ in ( 0, 1 ) $, $ \ lambda \ geq 0 $ and $ p > 1 $ is strictly smaller than the critical sobolev exponent.
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arxiv:2405.02120
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we summarize measurements of elliptic flow and higher order flow harmonics performed by the atlas experiment at the lhc. results on event - averaged flow measurements and event - plane correlations in pb + pb collisions are discussed along with the event - by - event flow measurements. further, we summarize results on flow in p + pb collisions.
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arxiv:1406.5541
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earlier estimates have argued that the baryon number violating scattering cross - section in the laboratory is exponentially small so it will never be observed, even for incoming 2 - particle energy well above the sphaleron energy of 9 tev. however, we argue in arxiv : 1505. 03690 that, due to the periodic nature of the sphaleron potential, the event rate for energies above the sphaleron energy may be high enough to be observed in the near future. that is, there is a discrepancy of about 70 orders of magnitude between the two estimates. here we argue why and how the multi - sphaleron processes are crucial to the event rate estimate, a very important " resonant tunneling " property that has not been taken into account before. we also summarize the input assumptions and reasoning adopted in our estimate, when compared to the earlier estimates.
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arxiv:1710.07223
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recent progress in image recognition has stimulated the deployment of vision systems at an unprecedented scale. as a result, visual data are now often consumed not only by humans but also by machines. existing image processing methods only optimize for better human perception, yet the resulting images may not be accurately recognized by machines. this can be undesirable, e. g., the images can be improperly handled by search engines or recommendation systems. in this work, we examine simple approaches to improve machine recognition of processed images : optimizing the recognition loss directly on the image processing network or through an intermediate input transformation model. interestingly, the processing model ' s ability to enhance recognition quality can transfer when evaluated on models of different architectures, recognized categories, tasks and training datasets. this makes the methods applicable even when we do not have the knowledge of future recognition models, e. g., when uploading processed images to the internet. we conduct experiments on multiple image processing tasks paired with imagenet classification and pascal voc detection as recognition tasks. with these simple yet effective methods, substantial accuracy gain can be achieved with strong transferability and minimal image quality loss. through a user study we further show that the accuracy gain can transfer to a black - box cloud model. finally, we try to explain this transferability phenomenon by demonstrating the similarities of different models ' decision boundaries. code is available at https : / / github. com / liuzhuang13 / transferable _ ra.
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arxiv:1910.09185
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we first consider immersions on compact manifolds with uniform $ l ^ p $ - bounds on the second fundamental form and uniformly bounded volume. we show compactness in arbitrary dimension and codimension, generalizing a classical result of j. langer. in the second part, this result is used to deduce a localized version, being more convenient for many applications, such as convergence proofs for geometric flows.
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arxiv:1201.4562
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we define a variant of the young integration on some kinds of self - similar sets which are called cellular self - similar sets. this variant is an analogue of the young integration defined on the unit interval. we give the criteria of the variant on cellular self - similar sets, and also show that the variant is a cyclic 1 - cocycle of the algebra of complex - valued h \ " older continuous functions on the cellular self - similar sets. this suggests that the cocycle is a variant of currents.
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arxiv:1612.03311
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we compute the particle currents induced on a bubble wall background at finite temperature in a model with cp violation in the higgs sector. using a field theory approach we show that fermionic currents arise at one loop, so that a suppression factor $ { \ cal o } ( h _ t \ phi / \ pi t ) ^ 2 $ with respect to previous computations is found. the contributions to the higgs currents are also derived and their relevancy for the spontaneous baryogenesis mechanism is discussed.
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arxiv:hep-ph/9504265
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the new transient x - ray pulsar xte j0111. 2 - 7317 was observed with advanced satellite for cosmology and astrophysics ( asca ) on 1998 november 18, a few days after its discovery with the proportional counter array onboard the rossi x - ray timing explorer. the source was detected at a flux level of 3. 6x10 ^ - 10 erg cm ^ - 2 s ^ - 1 in the 0. 7 - - 10. 0 kev band, which corresponds to the x - ray luminosity of 1. 8x10 ^ 38 erg s ^ - 1, if a distance of 65 kpc for this pulsar in the small magellanic cloud is assumed. nearly sinusoidal pulsations with a period of 30. 9497 + / - 0. 0004 s were unambiguously detected during the asca observation. the pulsed fraction is low and slightly energy dependent with average value of \ ~ 27 %. the energy spectrum shows a large soft excess below ~ 2 kev when fitted to a simple power - law type model. the soft excess is eliminated if the spectrum is fitted to an ` ` inversely broken power - law ' ' model, in which photon indices below and above a break energy of 1. 5 kev are 2. 3 and 0. 8, respectively. the soft excess can also be described by a blackbody or a thermal bremsstrahlung when the spectrum above ~ 2 kev is modeled by a power - law. in these models, however, the thermal soft component requires a very large emission zone, and hence it is difficult to explain the observed pulsations at energies below 2 kev. a bright state of the source enables us to identify a weak iron line feature at 6. 4 kev with an equivalent width of 50 + / - 14 ev. pulse phase resolved spectroscopy revealed a slight hardening of the spectrum and marginal indication of an increase in the iron line strength during the pulse maximum.
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arxiv:astro-ph/0003251
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an accurate line list for calcium oxide is presented covering transitions between all bound ro - vibronic levels from the five lowest electronic states \ x, \ ap, \ a, \ astate, and \ bstate. the ro - vibronic energies and corresponding wavefunctionts were obtained by solving the fully coupled schr \ " { o } dinger equation. \ textit { ab initio } potential energy, spin - orbit, and electronic angular momentum curves were refined by fitting to the experimental frequencies and experimentally derived energies available in the literature. using our refined model we could ( i ) reassign the vibronic states for a large portion of the experimentally derived energies [ van groenendael a., tudorie m., focsa c., pinchemel b., bernath p. f., 2005, j. mol. spectrosc., 234, 255 ], ( ii ) extended this list of energies to $ j = 79 - 118 $ and ( iii ) suggest a new description of the resonances from the \ a - - \ x \ system. we used high level \ textit { ab initio } electric dipole moments reported previously [ khalil h., brites v., le quere f., leonard c., 2011, chem. phys., 386, 50 ] to compute the einstein a coefficients. our work is the first fully coupled description of this system. our line list is the most complete catalogue of spectroscopic transitions available for $ ^ { 40 } $ ca $ ^ { 16 } $ o and is applicable for temperatures up to at least 5000 ~ k. cao has yet to be observed astronomically but its transitions are characterised by being particularly strong which should facilitate its detection. the cao line list is made available in an electronic form as supplementary data to this article and at \ url { www. exomol. com }.
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arxiv:1512.08987
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we suggest a new asymptotic representation for the solutions to the 2 - d wave equation with variable velocity with localized initial data. this representation is a generalization of the maslov canonical operator and gives the formulas for the relationship between initial localized perturbations and wave profiles near the wave fronts including the neighborhood of backtracking ( focal or turning ) and selfintersection points. we apply these formulas to the problem of a propagation of tsunami waves in the frame of so - called piston model. finally we suggest the fast asymptotically - numerical algorithm for simulation of tsunami wave over nonuniform bottom. in this first part we present the final formulas and some geometrical construction. the proofs concerning analytical calculations will be done in the second part.
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arxiv:math-ph/0601001
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in this paper, we are concerned with the compressible viscous magnetohydrodynamic ( mhd ) system and investigate the large time behavior of strong solutions near constant equilibrium. in the eighties, umeda, kawashima and shizuta initiated the dissipative mechanism for a rather general class of symmetric hyperbolic - parabolic systems. from the point of view of dissipativity, kawashima in his doctoral dissertation established the optimal time - decay estimates of $ l ^ { q } $ - $ l ^ { 2 } ( q \ in [ 1, 2 ) $ ) type for solutions to the mhd system. here, we shall improve kawashima ' s efforts and give more precise description for the large time asymptotic behavior of solutions, not only in extra lebesgue spaces but also in a full family of besov norms with the negative regularity index. precisely, we show that the $ l ^ { p } $ norm ( the slightly stronger $ \ dot { b } ^ { 0 } _ { p, 1 } $ one in fact ) of global solutions with the critical regularity, decays like $ t ^ { - d ( \ frac { 1 } { p } - \ frac { 1 } { 4 } ) } $ for $ t \ rightarrow \ infty $. in particular, taking $ p = 2 $ and $ d = 3 $ goes back to the classical time decay $ t ^ { - \ frac { 3 } { 4 } } $. we derive new estimates which are used to deal with the strong coupling between the magnetic field and fluid dynamics.
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arxiv:1710.00154
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recurrent neural networks have been widely used in sequence learning tasks. in previous studies, the performance of the model has always been improved by either wider or deeper structures. however, the former becomes more prone to overfitting, while the latter is difficult to optimize. in this paper, we propose a simple new model named thick - net, by expanding the network from another dimension : thickness. multiple parallel values are obtained via more sets of parameters in each hidden state, and the maximum value is selected as the final output among parallel intermediate outputs. notably, thick - net can efficiently avoid overfitting, and is easier to optimize than the vanilla structures due to the large dropout affiliated with it. our model is evaluated on four sequential tasks including adding problem, permuted sequential mnist, text classification and language modeling. the results of these tasks demonstrate that our model can not only improve accuracy with faster convergence but also facilitate a better generalization ability.
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arxiv:1911.08074
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$ \ newcommand { \ eps } { \ epsilon } \ newcommand { \ np } { \ mathsf { np } } \ newcommand { \ yes } { \ mathsf { yes } } \ newcommand { \ no } { \ mathsf { no } } \ newcommand { \ myminus } { \ text { - } } \ newcommand { \ bsat } { { \ mathsf { b } } } \ newcommand { \ threesat } { \ rm { 3 } \ myminus \ mathsf { sat } } \ newcommand { \ gapthreesat } { \ mathsf { \ forall \ exists } \ myminus { \ rm { 3 } } \ myminus \ mathsf { sat } } $ in 1991, papadimitriou and yannakakis gave a reduction implying the $ \ np $ - hardness of approximating the problem $ \ threesat $ with bounded occurrences. their reduction is based on expander graphs. we present an analogue of this result for the second level of the polynomial - time hierarchy based on superconcentrator graphs. this resolves an open question of ko and lin ( 1995 ) and should be useful in deriving inapproximability results in the polynomial - time hierarchy. more precisely, we show that given an instance of $ \ gapthreesat $ in which every variable occurs at most $ \ bsat $ times ( for some absolute constant $ \ bsat $ ), it is $ \ pi _ 2 $ - hard to distinguish between the following two cases : $ \ yes $ instances, in which for any assignment to the universal variables there exists an assignment to the existential variables that satisfies all the clauses, and $ \ no $ instances in which there exists an assignment to the universal variables such that any assignment to the existential variables satisfies at most a $ 1 - \ eps $ fraction of the clauses. we also generalize this result to any level of the polynomial - time hierarchy.
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arxiv:1806.04080
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we present a programme of spectroscopic observations of galaxies in a sample of optically - selected clusters taken from the catalogue of couch et al ( 1991 ). previous rosat observations of these clusters have shown them to have lower x - ray luminosities, given their optical richness, than might be expected on the basis of local samples. in the present paper we extend this work by determining velocity dispersions of a subsample of the clusters. we confirm the dynamical reality of all but one of the original sample, and find velocity dispersions comparable with present - day clusters of equivalent comoving space density. thus, in the context of the $ l _ x - \ sigma $ relation for present - day clusters, there is evidence for a higher velocity dispersion at fixed x - ray luminosity. a key question is whether the high velocity dispersions are indicative of the gravitational potential. if they are, the x - ray luminosities measured in bower et al., 1994 ( paper i ), would then imply an implausibly low efficiency of x - ray generation. alternatively, the discrepancy could be explained if the clusters were systems of lower virial temperature, in which the apparent velocity dispersion is inflated by an infalling, unrelaxed halo. this might result either from an increase with redshift in the infall rate for clusters, or from the preferential selection of clusters embedded in filaments oriented along the line of sight. since clusters with similar properties can be found in local optically selected catalogues, we suggest that the latter explanation is more likely.
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arxiv:astro-ph/9705099
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we perform a thorough theoretical study of the electron properties of a generic cuo $ _ 2 $ plane in the framework of shubin - kondo - zener $ s $ - $ d $ exchange interaction that simultaneously describes the correlation between $ t _ c $ and the cu4 $ s $ energy. to this end, we apply the pokrovsky theory [ j. exp. theor. phys. 13, 447 - 450 ( 1961 ) ] for anisotropic gap bcs superconductors. it takes into account the thermodynamic fluctuations of the electric field in the dielectric direction perpendicular to the conducting layers. we microscopically derive a multiplicatively separable kernel able to describe the scattering rate in the momentum space, as well as the superconducting gap anisotropy within the bcs theory. these findings may be traced back to the fact that both the fermi liquid and the bcs reductions lead to one and the same reduced hamiltonian involving a separable interaction, such that a strong electron scattering corresponds to a strong superconducting gap and vice versa. moreover, the superconducting gap and the scattering rate vanish simultaneously along the diagonals of the brillouin zone. we would like to stress that our theoretical study reproduces the phenomenological analysis of other authors aiming at describing angle resolved photoemission spectroscopy measurements. within standard approximations one and the same $ s $ - $ d $ exchange hamiltonian describes gap anisotropy of the superconducting phase and the anisotropy of scattering rate of charge carriers in the normal phase.
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arxiv:2208.00936
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motivated by the problem of background independence of closed string field theory we study geometry on the infinite vector bundle of local fields over the space of conformal field theories ( cft ' s ). with any connection we can associate an excluded domain $ d $ for the integral of marginal operators, and an operator one - form $ \ omega _ \ mu $. the pair $ ( d, \ omega _ \ mu ) $ determines the covariant derivative of any correlator of local fields. we obtain interesting classes of connections in which $ \ omega _ \ mu $ ' s can be written in terms of cft data. for these connections we compute their curvatures in terms of four - point correlators, $ d $, and $ \ omega _ \ mu $. among these connections three are of particular interest. a flat, metric compatible connection $ \ hg $, and connections $ c $ and $ \ bar c $ having non - vanishing curvature, with $ \ bar c $ being metric compatible. the flat connection cannot be used to do parallel transport over a finite distance. parallel transport with either $ c $ or $ \ bar c $, however, allows us to construct a cft in the state space of another cft a finite distance away. the construction is given in the form of perturbation theory manifestly free of divergences.
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arxiv:hep-th/9304053
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the harmonic archipelago ha is obtained by attaching a large pinched annulus to every pair of consecutive loops of the hawaiian earring. we clarify the fundamental group pi1 ( ha ) as a quotient of the hawaiian earring group, provide a precise description of the kernel, show that both pi1 ( ha ) and the kernel are uncountable, and that pi1 ( ha ) has the indiscrete topology.
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arxiv:math/0501426
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we provide a new derivation of the hawking mass and willmore energy functionals for asymptotically ads spacetimes, by embedding einstein - ads gravity in conformal gravity. by construction, the evaluation of the four - dimensional conformal gravity action in a manifold with a conical defect produces a codimension - 2 conformal invariant functional $ l _ { \ sigma } $. the energy functionals are then particular cases of $ l _ { \ sigma } $ for einstein - ads and pure ads ambient spaces, respectively. the bulk action is finite for ads asymptotics and both hawking mass and willmore energy are finite as well. the result suggests a generic relation between conformal invariance and renormalization, where the codimension - 2 properties are inherited from the bulk gravity action.
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arxiv:2209.02006
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the energetic properties of a paired quantum hall state at landau level filling $ \ nu = 2 $ are investigated using variational monte carlo techniques. pairing is found to be energetically favorable in small magnetic fields because it introduces correlations between up and down spins that are absent in the traditional $ \ nu = 2 $ state. we find that pairing survives extrapolation to the thermodynamic limit.
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arxiv:cond-mat/9606107
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we prove two conjectures of paule and radu from their recent paper on broken k - diamond partitions.
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arxiv:1104.5430
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two different multivariate clustering techniques, the k - means partitioning method and the dirichlet process of mixture modeling, have been applied to the batse gamma - ray burst ( grb ) catalog, to obtain the optimum number of coherent groups. in the standard paradigm, grb are classified in only two groups, the long and short bursts. however, for both the clustering techniques, the optimal number of classes was found to be three, a result which is consistent with previous statistical analysis. in this classification, the long bursts are further divided into two groups which are primarily differentiated by their total fluence and duration and hence are named low and high fluence grb. analysis of grb with known red - shifts and spectral parameters suggests that low fluence grb have nearly constant isotropic energy output of 10 ^ { 52 } ergs while for the high fluence ones, the energy output ranges from 10 ^ { 52 } to 10 ^ { 54 } ergs. it is speculated that the three kinds of grbs reflect three different origins : mergers of neutron star systems, mergers between white dwarfs and neutron stars, and collapse of massive stars.
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arxiv:0705.4020
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it is shown that similarly to massless superparticle, classical global symmetry of the berkovits twistor string action is infinite - dimensional. we identify its superalgebra, whose finite - dimensional subalgebra contains $ psl ( 4 | 4, \ mathbb r ) $ superalgebra. in quantum theory this infinite - dimensional symmetry breaks down to $ sl ( 4 | 4, \ mathbb r ) $ one.
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arxiv:1405.7829
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in this paper, we report the observation of spin - orbit magnetoresistance ( somr ) in ferromagnetic metal / heavy metal / mgo system. we measure the magnetoresistance as the function of the thickness of heavy metal ( hm ) for cofeb / hm / mgo and cofeb / hm films where hm = pt and ta. besides the conventional spin hall magnetoresistance ( smr ) peak, the evidence of the somr is indicated by another peak of the mr ratio when the thickness of hm is around 1 ~ 2 nm for cofeb / hm / mgo films, which is absent for cofeb / hm films. we speculate the somr observed in our experiment originates from the spin - orbit coupling at the hm / mgo interface. we give the boundary conditions of our samples and calculate the theoretical magnetoresistance based on spin diffusion equation. based on the theoretical results, we can explain the two peaks we observe separately comes from the spin current generated by spin hall effect and by edelstein effect.
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arxiv:1909.12811
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let $ \ pi _ 1, \ pi _ 2 $ be irreducible admissible generic tempered representations of $ \ mathrm { gl } _ 2 ( f ) $ for some $ p $ - adic field $ f $ of odd residue characteristic. we introduce a natural notion of general $ ( \ pi _ 1 \ times \ pi _ 2 ) $ - integral data $ ( \ phi, g _ 1, g _ 2 ) \ in \ mathcal { s } ( f ^ 2 ) \ times \ mathrm { gl } _ 2 ( f ) ^ 2 $ at which the rankin - selberg integral can be evaluated. this is inspired by work of loeffler, and previous work of the author, on unramified zeta integrals. we then establish an integral variant of a result of jacquet - langlands for the local rankin - selberg zeta integral associated to $ \ pi _ 1 \ times \ pi _ 2 $ ; i. e. we show that for any such integral datum $ ( \ phi, g _ 1, g _ 2 ) $, we have $ $ \ frac { z ( \ phi, g _ 1w _ { \ pi _ 1 } ^ \ mathrm { new }, g _ 2w _ { \ pi _ 2 } ^ \ mathrm { new } ; s ) } { l ( \ pi _ 1 \ times \ pi _ 2, s ) } = \ phi ( \ phi, g _ 1w _ { \ pi _ 1 } ^ \ mathrm { new }, g _ 2w _ { \ pi _ 2 } ^ \ mathrm { new } ; q ^ s ) \ in \ mathbf { z } [ q ^ { - 1 }, \ sigma ^ 1 ] [ q ^ s, q ^ { - s } ] $ $ for a finite set $ \ sigma ^ 1 \ subseteq \ mathbf { c } ^ \ times $ of roots of unity and unitary character values, depending only on $ \ pi _ 1, \ pi _ 2 $. this is compatible with the notion of integrality coming from newforms $ f _ 1, f _ 2 $ of even integral weights, satisfying a mild local dihedral condition at $ 2 $. we show that if $ \ pi _ 1, \ pi _ 2 $ are local pieces of $ f _ 1, f _ 2 $ at any prime $ p $, the coefficient algebra is $ \ mathcal { o
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arxiv:2501.16972
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bose - einstein condensation is a remarkable manifestation of quantum statistics and macroscopic quantum coherence. superconductivity and superfluidity have their origin in bose - einstein condensation. ultracold quantum gases have provided condensates close to the original ideas of bose and einstein, while condensation of polaritons and magnons have introduced novel concepts of non - equilibrium condensation. here, we demonstrate a bose - einstein condensate ( bec ) of surface plasmon polaritons in lattice modes of a metal nanoparticle array. interaction of the nanoscale - confined surface plasmons with a room - temperature bath of dye molecules enables thermalization and condensation in picoseconds. the ultrafast thermalization and condensation dynamics are revealed by an experiment that exploits thermalization under propagation and the open cavity character of the system. a crossover from bec to usual lasing is realized by tailoring the band structure. this new condensate of surface plasmon lattice excitations has promise for future technologies due to its ultrafast, room - temperature and on - chip nature.
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arxiv:1706.01528
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we prove that the sequence spaces $ \ ell _ p \ oplus \ ell _ q $ and the spaces of infinite matrices $ \ ell _ p ( \ ell _ q ) $, $ \ ell _ q ( \ ell _ p ) $ and $ ( \ bigoplus _ { n = 1 } ^ \ infty \ ell _ p ^ n ) _ { \ ell _ q } $, which are isomorphic to certain besov spaces, have an almost greedy basis whenever $ 0 < p < 1 < q < \ infty $. more precisely, we custom - build almost greedy bases in such a way that the lebesgue parameters grow in a prescribed manner. our arguments critically depend on the extension of the dilworth - kalton - kutzarova method from [ s. j. dilworth, n. j. kalton, and d. kutzarova, on the existence of almost greedy bases in banach spaces, studia math. 159 ( 2003 ), no. 1, 67 - 101 ], which was originally designed for constructing almost greedy bases in banach spaces, to make it valid for direct sums of mixed - normed spaces with nonlocally convex components. additionally, we prove that the fundamental functions of all almost greedy bases of these spaces grow as $ ( m ^ { 1 / q } ) _ { m = 1 } ^ \ infty $.
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arxiv:2208.10203
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i argue against the widespread notion that manifest de sitter invariance on the full de sitter manifold is either useful or even attainable in gauge theories. green ' s functions and propagators computed in a de sitter invariant gauge are generally more complicated than in some noninvariant gauges. what is worse, solving the gauge - fixed field equations in a de sitter invariant gauge generally leads to violations of the original, gauge invariant field equations. the most interesting free quantum field theories possess no normalizable, de sitter invariant states. this precludes the existence of de sitter invariant propagators. even had such propagators existed, infrared divergent processes would still break de sitter invariance.
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arxiv:gr-qc/0408002
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the phase and phase - shift resulting from signal modification ka - band exciter ( kex ) it supplies telemetry data. s - band transmitter is used for radio science experiments. the transmitter receives signal from the rfs, amplifies and multiplies the signal, sending a 2290 mhz signal to the antenna. filter microwave emitter allow only microwaves of a given frequency to be emitted, there is a polarizing element. there are two - bypass filters and a wave - guide. the bypass filters allow different feed polarizations, receiving and transmitting. = = references = =
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https://en.wikipedia.org/wiki/Radio_science_subsystem
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in this lecture, i put forward conjectures asserting that, in all noncommutative field theories, ( 1 ) open wilson lines and their descendants constitute a complete set of interpolating operators of ` noncommutative dipoles ', obeying dipole relation, ( 2 ) infrared dynamics of the noncommutative dipoles is dual to ultraviolet dynamics of the elementary noncommutative fields, and ( 3 ) open string field theory is a sort of noncommutative field theory, whose open wilson lines are interpolating operators for closed strings. i substantiate these conjectures by various intuitive arguments and explicit computations of one - and two - loop feynman diagrammatics.
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arxiv:hep-th/0207108
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we prove a milnor - l \ ^ e type fibration theorem for a subanalytic map $ f : x \ to y $ between subanalytic sets $ x \ subset \ mathbb { r } ^ m $ and $ y \ subset \ mathbb { r } ^ n $. moreover, if $ f $ extends to an analytic map $ \ mathbb { r } ^ m \ to \ mathbb { r } ^ n $, we define the singular set and the discriminant set of $ f $, in a stratified sense. then we give milnor - l \ ^ e type fibration theorems for $ f $ outside its discriminant, as well as over it. we give examples of each situation approached in this paper.
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arxiv:1806.05349
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in recent years, a number of observations have been made of the transits of ' hot jupiters ', such as hd 189733b, which have been modelled to derive atmospheric structure and composition. as measurement techniques improve, the transit spectra of ' super - earths ' such as gj 1214b are becoming better constrained, allowing model atmospheres to be fitted for this class of planet also. while it is not yet possible to constrain the atmospheric states of small planets such as the earth or cold planets like jupiter, this may become practical in the coming decades and if so, it is of interest to determine what we might infer from such measurements. here we have constructed atmospheric models of the solar system planets from 0. 4 - 15. 5 microns that are consistent with ground - based and satellite observations and from these calculate the primary transit and secondary eclipse spectra ( with respect to the sun and typical m - dwarfs ) that would be observed by a ' remote observer ', many light years away. from these spectra we test what current retrieval models might infer about their atmospheres and compare these with the ' ground truths ' in order to assess : a ) the inherent uncertainties in transit spectra observations ; b ) the relative merits of primary transit and secondary eclipse spectra ; and c ) the advantages of directly imaged spectra. we find that secondary eclipses would not give sufficient information, but that primary transits give much better determination. we find that a single transit of jupiter in front of the sun could potentially be used to determine temperature and stratospheric composition, but for the earth the mean atmospheric composition could only be determined if it were orbiting an m - dwarf. for both planets we note that direct imaging with sufficient nulling of the light from the parent star provides the best method of determining the atmospheric properties of such planets.
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arxiv:1408.3914
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we present inferflow, an efficient and highly configurable inference engine for large language models ( llms ). with inferflow, users can serve most of the common transformer models by simply modifying some lines in corresponding configuration files, without writing a single line of source code. compared with most existing inference engines, inferflow has some key features. first, by implementing a modular framework of atomic build - blocks and technologies, inferflow is compositionally generalizable to new models. second, 3. 5 - bit quantization is introduced in inferflow as a tradeoff between 3 - bit and 4 - bit quantization. third, hybrid model partitioning for multi - gpu inference is introduced in inferflow to better balance inference speed and throughput than the existing partition - by - layer and partition - by - tensor strategies.
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arxiv:2401.08294
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we call a coupling of two stochastic processes which maximizes the time until the first disagreement a maximal agreement coupling. we show that such a coupling always exists. furthermore, it is possible to construct a lower bound on the disagreement time which is independent of one of the two processes.
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arxiv:1608.01511
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understanding equilibration and thermalization in isolated many - body quantum systems is a central challenge in quantum physics. the traditional approach focuses on the study of the full state of the quantum system which, at equilibrium, is best described by the diagonal ensemble. here, we present observable statistical mechanics, a novel paradigm that shifts attention from the full quantum state to the statistics of measurement outcomes. this approach is grounded in the maximum observable entropy principle, positing that equilibrium measurement statistics tend to maximize observable entropy under conserved average energy. by focusing on accessible measurements, the theory accurately predicts equilibrium probability distributions without needing detailed microscopic information like the energy eigenstates. extensive numerical experiments on 7 spin - 1 / 2 hamiltonians demonstrate the broad applicability and robustness of this framework.
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arxiv:2309.15173
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cell detection and segmentation are integral parts of automated systems in digital pathology. encoder - decoder networks have emerged as a promising solution for these tasks. however, training of these networks has typically required full boundary annotations of cells, which are labor - intensive and difficult to obtain on a large scale. however, in many applications, such as cell counting, weaker forms of annotations - - such as point annotations or approximate cell counts - - can provide sufficient supervision for training. this study proposes a new mixed - supervision approach for training multitask networks in digital pathology by incorporating cell counts derived from the eyeballing process - - a quick visual estimation method commonly used by pathologists. this study has two main contributions : ( 1 ) it proposes a mixed - supervision strategy for digital pathology that utilizes cell counts obtained by eyeballing as an auxiliary supervisory signal to train a multitask network for the first time. ( 2 ) this multitask network is designed to concurrently learn the tasks of cell counting and cell localization, and this study introduces a consistency loss that regularizes training by penalizing inconsistencies between the predictions of these two tasks. our experiments on two datasets of hematoxylin - eosin stained tissue images demonstrate that the proposed approach effectively utilizes the weakest form of annotation, improving performance when stronger annotations are limited. these results highlight the potential of integrating eyeballing - derived ground truths into the network training, reducing the need for resource - intensive annotations.
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arxiv:2412.15392
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various approaches to gene selection for cancer classification based on microarray data can be found in the literature and they may be grouped into two categories : univariate methods and multivariate methods. univariate methods look at each gene in the data in isolation from others. they measure the contribution of a particular gene to the classification without considering the presence of the other genes. in contrast, multivariate methods measure the relative contribution of a gene to the classification by taking the other genes in the data into consideration. multivariate methods select fewer genes in general. however, the selection process of multivariate methods may be sensitive to the presence of irrelevant genes, noises in the expression and outliers in the training data. at the same time, the computational cost of multivariate methods is high. to overcome the disadvantages of the two types of approaches, we propose a hybrid method to obtain gene sets that are small and highly discriminative. we devise our hybrid method from the univariate maximum likelihood method ( lik ) and the multivariate recursive feature elimination method ( rfe ). we analyze the properties of these methods and systematically test the effectiveness of our proposed method on two cancer microarray datasets. our experiments on a leukemia dataset and a small, round blue cell tumors dataset demonstrate the effectiveness of our hybrid method. it is able to discover sets consisting of fewer genes than those reported in the literature and at the same time achieve the same or better prediction accuracy.
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arxiv:1506.02085
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cluster number counts offer sensitive probes of the dark energy if and only if the _ evolution _ of the cluster mass versus observable relation ( s ) is well calibrated. we investigate the potential for internal calibration by demanding consistency in the counts as a function of the observable. in the context of a constant dark energy equation of state, known initial fluctuation amplitude expected from the cmb, universal underlying mass function, and an idealized selection, we find that the ambiguity from the normalization of the mass - observable relationships, or an extrapolation of external mass - observable determinations from higher masses, can be largely eliminated with a sufficiently deep survey, even allowing for an arbitrary evolution. more generally, number counts as a function of both the redshift and the observable enable strong consistency tests on assumptions made in modelling the mass - observable relations and cosmology.
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arxiv:astro-ph/0301416
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we build and probe a $ \ mathbb { z } _ 2 $ spin liquid in a programmable quantum device, the d - wave dw - 2000q. specifically, we observe the classical 8 - vertex and 6 - vertex ( spin ice ) states and transitions between them. to realize this state of matter, we design a hamiltonian with combinatorial gauge symmetry using only pairwise - qubit interactions and a transverse field, i. e., interactions which are accessible in this quantum device. the combinatorial gauge symmetry remains exact along the full quantum annealing path, landing the system onto the classical 8 - vertex model at the endpoint of the path. the output configurations from the device allows us to directly observe the loop structure of the classical model. moreover, we deform the hamiltonian so as to vary the weights of the 8 vertices and show that we can selectively attain the classical 6 - vertex ( ice ) model, or drive the system into a ferromagnetic state. we present studies of the classical phase diagram of the system as function of the 8 - vertex deformations and effective temperature, which we control by varying the relative strengths of the programmable couplings, and we show that the experimental results are consistent with theoretical analysis. finally, we identify additional capabilities that, if added to these devices, would allow us to realize $ \ mathbb { z } _ 2 $ quantum spin liquids on which to build topological qubits.
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arxiv:2009.07853
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modern datasets are often in the form of matrices or arrays, potentially having correlations along each set of data indices. for example, data involving repeated measurements of several variables over time may exhibit temporal correlation as well as correlation among the variables. a possible model for matrix - valued data is the class of matrix normal distributions, which is parametrized by two covariance matrices, one for each index set of the data. in this article we describe an extension of the matrix normal model to accommodate multidimensional data arrays, or tensors. we generate a class of array normal distributions by applying a group of multilinear transformations to an array of independent standard normal random variables. the covariance structures of the resulting class take the form of outer products of dimension - specific covariance matrices. we derive some properties of these covariance structures and the corresponding array normal distributions, discuss maximum likelihood and bayesian estimation of covariance parameters and illustrate the model in an analysis of multivariate longitudinal network data.
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arxiv:1008.2169
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in this study, we address challenges in designing quantum information processors based on electron spin qubits in electrostatically - defined quantum dots ( qds ). numerical calculations of charge stability diagrams are presented for a realistic double qd device geometry. these methods generaize to linear qd arrays, and are based on determining the effective parameters of a hubbard model hamiltonian that is then diagonalized to find the many - electron ground state energy. these calculations enable the identification of gate voltage ranges that maintain desired charge states during qubit manipulation, and also account for electrical cross - talk between qds. as a result, the methods presented here promise to be a valuable tool for developing scalable spin qubit quantum processors.
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arxiv:2402.15499
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this paper shows that accretion of positronium plasma between 0. 01 to 14s after the big bang could have created small black holes contributing at least 1 percent of the dark matter present today, with uncertainties ranging from 10 percent or more. general relativistic magnetohydrodynamic ( grmhd ) simulations newly adapted to the early universe confirm that accretion is due to magneto - rotational instability ( mri ) in a rotating plasma. by contrast with bondi accretion producing primordial masses bigger than the sun, mri could produce masses 10 ^ { 15 - 18 } g observable by their hawking radiation contributing to background gamma rays.
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arxiv:2403.04227
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deep reinforcement learning ( drl ) policies are highly susceptible to adversarial noise in observations, which poses significant risks in safety - critical scenarios. the challenge inherent to adversarial perturbations is that by altering the information observed by the agent, the state becomes only partially observable. existing approaches address this by either enforcing consistent actions across nearby states or maximizing the worst - case value within adversarially perturbed observations. however, the former suffers from performance degradation when attacks succeed, while the latter tends to be overly conservative, leading to suboptimal performance in benign settings. we hypothesize that these limitations stem from their failing to account for partial observability directly. to this end, we introduce a novel objective called adversarial counterfactual error ( acoe ), defined on the beliefs about the true state and balancing value optimization with robustness. to make acoe scalable in model - free settings, we propose the theoretically - grounded surrogate objective cumulative - acoe ( c - acoe ). our empirical evaluations on standard benchmarks ( mujoco, atari, and highway ) demonstrate that our method significantly outperforms current state - of - the - art approaches for addressing adversarial rl challenges, offering a promising direction for improving robustness in drl under adversarial conditions. our code is available at https : / / github. com / romanbelaire / acoe - robust - rl.
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arxiv:2406.04724
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nature. some notable structuralists include : paul benacerraf : a philosopher known for his work in the philosophy of mathematics, particularly his paper " what numbers could not be, " which argues for a structuralist view of mathematical objects. stewart shapiro : another prominent philosopher who has developed and defended structuralism, especially in his book philosophy of mathematics : structure and ontology. = = = objects versus mappings = = = frege famously distinguished between functions and objects. according to his view, a function is a kind of ‘ incomplete ’ entity that maps arguments to values, and is denoted by an incomplete expression, whereas an object is a ‘ complete ’ entity and can be denoted by a singular term. frege reduced properties and relations to functions and so these entities are not included among the objects. some authors make use of frege ' s notion of ‘ object ’ when discussing abstract objects. but though frege ' s sense of ‘ object ’ is important, it is not the only way to use the term. other philosophers include properties and relations among the abstract objects. and when the background context for discussing objects is type theory, properties and relations of higher type ( e. g., properties of properties, and properties of relations ) may be all be considered ‘ objects ’. this latter use of ‘ object ’ is interchangeable with ‘ entity. ’ it is this more broad interpretation that mathematicians mean when they use the term ' object '. = = see also = = abstract object exceptional object impossible object list of mathematical objects list of mathematical shapes list of shapes list of surfaces list of two - dimensional geometric shapes mathematical structure = = notes = = = = references = = citations further reading azzouni, j., 1994. metaphysical myths, mathematical practice. cambridge university press. burgess, john, and rosen, gideon, 1997. a subject with no object. oxford univ. press. davis, philip and reuben hersh, 1999 [ 1981 ]. the mathematical experience. mariner books : 156 – 62. gold, bonnie, and simons, roger a., 2011. proof and other dilemmas : mathematics and philosophy. mathematical association of america. hersh, reuben, 1997. what is mathematics, really? oxford university press. sfard, a., 2000, " symbolizing mathematical reality into being, or how mathematical discourse and mathematical objects create each other, " in cobb, p., et al., symbolizing and communicating in mathematics classrooms : perspectives on discourse, tools and instructional design. lawrence erlbaum.
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https://en.wikipedia.org/wiki/Mathematical_object
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we propose a kinematic method based on a factorization formula for precisely measuring the top quark mass $ m _ t $ in $ pp $ collisions using boosted top jets with light soft drop grooming. by using light grooming, which is an order of magnitude less aggressive than typical grooming, we retain a universal description of the top mass scheme and decay effects, while still effectively removing soft contamination from the top jet. we give field theory results for the hadronization corrections for jets induced by a heavy top quark, showing they are described by a universal hadronic parameter that also appears for groomed light quark jets. an important phenomenological application of our results is that one can obtain $ m _ t $ in a short distance scheme by fitting the hadron level jet mass distributions, predicted by our factorization formula, to data or by monte - carlo calibration. the peaked distributions for $ pp $ and $ e ^ + e ^ - $ collisions are similar, up to sensitivity to underlying event which is significantly reduced by soft drop. since soft drop implies that the $ t $ and $ \ bar t $ jet masses each can be independently measured, the analysis enables the use of lepton + jet samples.
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arxiv:1708.02586
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in a 3 - manifold m, let k be a knot and r be an annulus which meets k transversely. we define the notion of the pair ( r, k ) being caught by a surface q in the exterior of the link given by k and the boundary curves of r. for a caught pair ( r, k ), we consider the knot k ^ n gotten by twisting k n times along r and give a lower bound on the bridge number of k ^ n with respect to heegaard splittings of m - - as a function of n, the genus of the splitting, and the catching surface q. as a result, the bridge number of k ^ n tends to infinity with n. in application, we look at a family of knots k ^ n found by teragaito that live in a small seifert fiber space m and where each k ^ n admits a dehn surgery giving the 3 - sphere. we show that the bridge number of k ^ n with respect to any genus 2 heegaard splitting of m tends to infinity with n. this contrasts with other work of the authors as well as with the conjectured picture for knots in lens spaces that admit dehn surgeries giving the 3 - sphere.
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arxiv:1303.7018
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quantum computing holds immense potential for solving classically intractable problems by leveraging the unique properties of quantum mechanics. the scalability of quantum architectures remains a significant challenge. multi - core quantum architectures are proposed to solve the scalability problem, arising a new set of challenges in hardware, communications and compilation, among others. one of these challenges is to adapt a quantum algorithm to fit within the different cores of the quantum computer. this paper presents a novel approach for circuit partitioning using deep reinforcement learning, contributing to the advancement of both quantum computing and graph partitioning. this work is the first step in integrating deep reinforcement learning techniques into quantum circuit mapping, opening the door to a new paradigm of solutions to such problems.
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arxiv:2401.17976
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the alignment dependence of the ionization behavior of h $ _ 2 $ exposed to intense ultrashort laser pulses is investigated on the basis of solutions of the full time - dependent schr \ " odinger equation within the fixed - nuclei and dipole approximation. the total ionization yields as well as the energy - resolved electron spectra have been calculated for a parallel and a perpendicular orientation of the molecular axis with respect to the polarization axis of linear polarized laser pulses. for most, but not all considered laser peak intensities the parallel aligned molecules are easier to ionize. furthermore, it is shown that the velocity formulation of the strong - field approximation predicts a simple interference pattern for the ratio of the energy - resolved electron spectra obtained for the two orientations, but this is not confirmed by the full ab initio results.
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arxiv:0909.4483
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the cosmic background imager ( cbi ) is a 13 - element interferometer designed to image intrinsic anisotropies in the cosmic microwave background ( cmb ) on arcminute scales. a review of the capabilities of the instrument is presented, together with a discussion of observations which have been taken over the past 9 months from the atacama desert of chile. we present preliminary high - resolution mosaiced images of the cmb obtained from recent cbi data and discuss topics which the cbi will address in the near future.
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arxiv:astro-ph/0101171
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deep learning in image registration ( dlir ) methods have been tremendously successful in image registration due to their speed and ability to incorporate weak label supervision at training time. however, existing dlir methods forego many of the benefits and invariances of optimization methods. the lack of a task - specific inductive bias in dlir methods leads to suboptimal performance, especially in the presence of domain shift. our method aims to bridge this gap between statistical learning and optimization by explicitly incorporating optimization as a layer in a deep network. a deep network is trained to predict multi - scale dense feature images that are registered using a black box iterative optimization solver. this optimal warp is then used to minimize image and label alignment errors. by implicitly differentiating end - to - end through an iterative optimization solver, we explicitly exploit invariances of the correspondence matching problem induced by the optimization, while learning registration and label - aware features, and guaranteeing the warp functions to be a local minima of the registration objective in the feature space. our framework shows excellent performance on in - domain datasets, and is agnostic to domain shift such as anisotropy and varying intensity profiles. for the first time, our method allows switching between arbitrary transformation representations ( free - form to diffeomorphic ) at test time with zero retraining. end - to - end feature learning also facilitates interpretability of features and arbitrary test - time regularization, which is not possible with existing dlir methods.
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arxiv:2406.07361
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perturbation theory ( pt ) applied to a cosmological density field with gaussian initial fluctuations suggests a specific hierarchy for the correlation functions when the variance is small. in particular quantitative predictions have been made for the moments and the shape of the one - point probability distribution function ( pdf ) of the top - hat smoothed density. in this paper we perform a series of systematic checks of these predictions against n - body computations both in 2d and 3d with a wide range of featureless power spectra. in agreement with previous studies, we found that the reconstructed pdf - s work remarkably well down to very low probabilities, even when the variance approaches unity. our results for 2d reproduce the features for the 3d dynamics. in particular we found that the pt predictions are more accurate for spectra with less power on small scales. the nonlinear regime has been explored with various tools, pdf - s, moments and void probability function ( vpf ). these studies have been done with unprecedented dynamical range, especially for the 2d case, allowing in particular more robust determinations of the asymptotic behaviour of the vpf. we have also introduced a new method to determine the moments based on the factorial moments. results using this method and taking into account the finite volume effects are presented.
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arxiv:astro-ph/9707009
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a fundamental task in wireless communication is channel estimation : compute the channel parameters a signal undergoes while traveling from a transmitter to a receiver. in the case of delay - doppler channel, a widely used method is the matched filter algorithm. it uses a pseudo - random sequence of length n, and, in case of non - trivial relative velocity between transmitter and receiver, its computational complexity is o ( n ^ { 2 } log ( n ) ). in this paper we introduce a novel approach of designing sequences that allow faster channel estimation. using group representation techniques we construct sequences, which enable us to introduce a new algorithm, called the flag method, that significantly improves the matched filter algorithm. the flag method finds the channel parameters in o ( mnlog ( n ) ) operations, for channel of sparsity m. we discuss applications of the flag method to gps, radar system, and mobile communication as well.
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arxiv:1208.4405
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we investigate the relationship between the zeeman interaction and the inversion asymmetry induced spin orbit interactions ( rashba and dresselhaus sois ) in gaas hole quantum point contacts. the presence of a strong soi results in crossing and anti - crossing of adjacent spin - split hole subbands in a magnetic field. we demonstrate theoretically and experimentally that the anti - crossing energy gap depends on the interplay between the soi terms and the highly anisotropic hole g tensor, and that this interplay can be tuned by selecting the crystal axis along which the current and magnetic field are aligned. our results constitute independent detection and control of the dresselhaus and rashba sois in hole systems, which could be of importance for spintronics and quantum information applications.
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arxiv:1703.04233
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we report the highest - redshift detection of [ o i ] 63 $ \ mu $ m from a luminous quasar, j2054 - 0005, at $ z = 6. 04 $ based on the atacama large millimeter / sub - millimeter array band 9 observations. the [ o i ] 63 $ \ mu $ m line luminosity is $ ( 4. 5 \ pm1. 5 ) \ times 10 ^ { 9 } ~ l _ { \ rm \ odot } $, corresponding to the [ o i ] 63 $ \ mu $ m - to - far - infrared luminosity ratio of $ \ approx 6. 7 \ times10 ^ { - 4 } $, which is consistent with the value obtained in the local universe. remarkably, [ o i ] 63 $ \ mu $ m is as bright as [ c ii ] 158 $ \ mu $ m, resulting in the [ o i ] - to - [ c ii ] line luminosity ratio of $ 1. 3 \ pm0. 5 $. based on a careful comparison of the luminosity ratios of [ o i ] 63 $ \ mu $ m, [ c ii ] 158 $ \ mu $ m, and dust continuum emission to models of photo - dissociation regions, we find that j2054 - 0005 has a gas density log ( $ n _ { \ rm h } $ / cm $ ^ { - 3 } $ ) $ = 3. 7 \ pm0. 3 $ and an incident far - ultraviolet radiation field of log ( $ g / g _ { \ rm 0 } $ ) $ = 3. 0 \ pm0. 1 $, showing that [ o i ] 63 $ \ mu $ m serves as an important coolant of the dense and warm gas in j2054 - 0005. a close examination of the [ o i ] and [ c ii ] line profiles suggests that the [ o i ] line may be partially self - absorbed, however deeper observations are needed to verify this conclusion. regardless, the gas density and incident radiation field are in a broad agreement with the values obtained in nearby star - forming galaxies and objects with [ o i ] 63 $ \ mu $ m observations at $ z = 1 - 3 $ with the herschel space observatory. these results demonstrate the power of alma high - frequency observations targeting [ o i ] 63 $ \ mu $ m to examine the properties of photo - dissociation regions in high - redshift galaxies.
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arxiv:2408.09944
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the concept of gyrogroups is a generalization of groups which do not explicitly have associativity. in this paper, the notion of fuzzy gyronorms on gyrogroups is introduced. the relations of fuzzy metrics ( in the sense of george and veeramani ), fuzzy gyronorms and gyronorms on gyrogroups are studied. also, the fuzzy metric structures on fuzzy normed gyrogroups are discussed. in the last, the fuzzy metric completion of a gyrogroup with an invariant metric are studied. we mainly show that let $ d $ be an invariant metric on a gyrogroup $ g $ and $ ( \ widehat { g }, \ widehat { d } ) $ is the metric completion of the metric space $ ( g, d ) $ ; then for any continuous $ t $ - norm $ \ ast $, the standard fuzzy metric space $ ( \ widehat { g }, m _ { \ widehat { d } }, \ ast ) $ of $ ( \ widehat { g }, \ widehat { d } ) $ is the ( up to isometry ) unique fuzzy metric completion of the standard fuzzy metric space $ ( g, m _ d, \ ast ) $ of $ ( g, d ) $ ; furthermore, $ ( \ widehat { g }, m _ { \ widehat { d } }, \ ast ) $ is a fuzzy metric gyrogroup containing $ ( g, m _ d, \ ast ) $ as a dense fuzzy metric subgyrogroup and $ m _ { \ widehat { d } } $ is invariant on $ \ widehat { g } $. applying this result, we obtain that every gyrogroup $ g $ with an invariant metric $ d $ admits an ( up to isometric ) unique complete metric space $ ( \ widehat { g }, \ widehat { d } ) $ of $ ( g, d ) $ such that $ \ widehat { g } $ with the topology introduced by $ \ widehat { d } $ is a topology gyrogroup containing $ g $ as a dense subgyrogroup and $ \ widehat { d } $ is invariant on $ \ widehat { g } $.
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arxiv:2006.09215
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muons from cosmic - ray interactions in the atmosphere provide a high - statistics source of particles that can be used to study the performance and calibration of the atlas detector. cosmic - ray muons can penetrate to the cavern and deposit energy in all detector subsystems. such events have played an important role in the commissioning of the detector since the start of the installation phase in 2005 and were particularly important for understanding the detector performance in the time prior to the arrival of the first lhc beams. global cosmic - ray runs were undertaken in both 2008 and 2009 and these data have been used through to the early phases of collision data - taking as a tool for calibration, alignment and detector monitoring. these large datasets have also been used for detector performance studies, including investigations that rely on the combined performance of different subsystems. this paper presents the results of performance studies related to combined tracking, lepton identification and the reconstruction of jets and missing transverse energy. results are compared to expectations based on a cosmic - ray event generator and a full simulation of the detector response.
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arxiv:1011.6665
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obtaining sparse, interpretable representations of observable data is crucial in many machine learning and signal processing tasks. for data representing flows along the edges of a graph, an intuitively interpretable way to obtain such representations is to lift the graph structure to a simplicial complex : the eigenvectors of the associated hodge - laplacian, respectively the incidence matrices of the corresponding simplicial complex then induce a hodge decomposition, which can be used to represent the observed data in terms of gradient, curl, and harmonic flows. in this paper, we generalize this approach to cellular complexes and introduce the flow representation learning problem, i. e., the problem of augmenting the observed graph by a set of cells, such that the eigenvectors of the associated hodge laplacian provide a sparse, interpretable representation of the observed edge flows on the graph. we show that this problem is np - hard and introduce an efficient approximation algorithm for its solution. experiments on real - world and synthetic data demonstrate that our algorithm outperforms state - of - the - art methods with respect to approximation error, while being computationally efficient.
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arxiv:2309.01632
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we construct solutions to five dimensional minimal supergravity using an atiyah - hitchin base space. in examining the structure of solutions we show that they generically contain a singularity either on the atiyah - hitchin bolt or at larger radius where there is a singular solitonic boundary. however for most points in parameter space the solution exhibits a velocity of light surface ( analogous to what appears in a goedel space - time ) that shields the singularity. for these solutions, all closed time - like curves are causally disconnected from the rest of the space - time in that they exist within the velocity of light surface, which null geodesics are unable to cross. the singularities in these solutions are thus found to be hidden behind the velocity of light surface and so are not naked despite the lack of an event horizon. outside of this surface the space - time is geodesically complete, asymptotically flat and can be arranged so as not to contain closed time - like curves at infinity. the rest of parameter space simply yields solutions with naked singularities.
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arxiv:0804.4159
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a comparative study of the dielectric properties and electric polarization of multiferroics gdmn2o5 and gd0. 8ce0. 2mn2o5 has been carried out in the temperature range from 5 up to 300 k. the polarization properties in the ferroelectric state that forms due to a charge ordering and exchange striction have been studied at t less than 30 k. the properties of the restricted polar phase separation domains formed in the crystals containing ions mn3 + and mn4 + have been studied, too. these domains exhibit the electric polarization in the temperature range from 5 k to some temperatures tf lager than tc. such a high - temperature polarization is due to the frozen superparaelectric state of the restricted polar domains.
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arxiv:1803.02126
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the association between star - forming regions and x - ray emission was discovered over 30 years ago. we now know that essentially all young stellar objects, t tauri stars and protostars, are x - ray emitters, although the case of the youngest, class ~ 0 protostars, is less clear. the paper highlights x - ray emission and absorption mechanisms, and summarizes x - ray observations of young stellar objects. the impact of the vlt on the characterization of the new x - ray sources is also briefly discussed.
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arxiv:astro-ph/0111271
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information extraction and user intention identification are central topics in modern query understanding and recommendation systems. in this paper, we propose deepprobe, a generic information - directed interaction framework which is built around an attention - based sequence to sequence ( seq2seq ) recurrent neural network. deepprobe can rephrase, evaluate, and even actively ask questions, leveraging the generative ability and likelihood estimation made possible by seq2seq models. deepprobe makes decisions based on a derived uncertainty ( entropy ) measure conditioned on user inputs, possibly with multiple rounds of interactions. three applications, namely a rewritter, a relevance scorer and a chatbot for ad recommendation, were built around deepprobe, with the first two serving as precursory building blocks for the third. we first use the seq2seq model in deepprobe to rewrite a user query into one of standard query form, which is submitted to an ordinary recommendation system. secondly, we evaluate deepprobe ' s seq2seq model - based relevance scoring. finally, we build a chatbot prototype capable of making active user interactions, which can ask questions that maximize information gain, allowing for a more efficient user intention idenfication process. we evaluate first two applications by 1 ) comparing with baselines by bleu and auc, and 2 ) human judge evaluation. both demonstrate significant improvements compared with current state - of - the - art systems, proving their values as useful tools on their own, and at the same time laying a good foundation for the ongoing chatbot application.
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arxiv:1707.05470
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the influence of disorder on the transmission through periodic waveguides is studied. using a canonical form of the transfer matrix we investigate dependence of the lyapunov exponent $ \ gamma $ on the frequency $ \ nu $ and magnitude of the disorder $ \ sigma $. it is shown that in the bulk of the bands $ \ gamma \ sim \ sigma ^ 2 $, while near the band edges it has the order $ \ gamma \ sim \ sigma ^ { 2 / 3 } $. this dependence is illustrated by numerical simulations.
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arxiv:1110.4132
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the eigenvalue problem is a fundamental problem in scientific computing. in this paper, we first give the error analysis for a single step or sweep of jacobi ' s method in floating point arithmetic. then we propose a mixed precision preconditioned jacobi method for the symmetric eigenvalue problem : we first compute the eigenvalue decomposition of a real symmetric matrix by an eigensolver at low precision and we obtain a low - precision matrix of eigenvectors ; then by using the high - precision modified gram - schmidt orthogonalization process, a high - precision orthogonal matrix is obtained, which is used as an initial guess for jacobi ' s method. the rounding error analysis of the proposed method is established under some conditions. we also present a mixed precision preconditioned one - sided jacobi method for the singular value problem and the corresponding rounding error analysis is discussed. numerical experiments on cpus and gpus are reported to illustrate the efficiency of the proposed method over the original jacobi method.
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arxiv:2211.03339
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glacial - interglacial cycles are large variations in continental ice mass and greenhouse gases, which have dominated climate variability over the quaternary. the dominant periodicity of the cycles is $ \ sim $ 40 kyr before the so - called middle pleistocene transition between $ \ sim $ 1. 2 and $ \ sim $ 0. 7 myr ago, and it is $ \ sim $ 100 kyr after the transition. in this paper, the dynamics of glacial - interglacial cycles are investigated using a phase oscillator model forced by the time - varying incoming solar radiation ( insolation ). we analyze the bifurcations of the system and show that strange nonchaotic attractors appear through nonsmooth saddle - node bifurcations of tori. the bifurcation analysis indicates that mode - locking is likely to occur for the 41 kyr glacial cycles but not likely for the 100 kyr glacial cycles. the sequence of mode - locked 41 kyr cycles is robust to small parameter changes. however, the sequence of 100 kyr glacial cycles can be sensitive to parameter changes when the system has a strange nonchaotic attractor.
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arxiv:1506.04628
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we consider the correspondence assigning to every radon measure on two tychonoff coordinate spaces the set of probability measures with these marginals. it is proved that this correspondence is continuous.
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arxiv:math/0502474
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in this paper, we investigate frequency - selective dynamic scattering array ( dsa ), a versatile antenna structure capable of performing joint wave - based computing and radiation by transitioning signal processing tasks from the digital domain to the electromagnetic ( em ) domain. the numerical results demonstrate the potential of dsas to produce space - frequency superdirective responses with minimal usage of radiofrequency ( rf ) chains, making it particularly attractive for future holographic multiple - input multiple - output ( mimo ) systems.
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arxiv:2502.07336
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we study surface effects of neutron $ ^ { 3 } p _ { 2 } $ superfluids in neutron stars. $ ^ { 3 } p _ { 2 } $ superfluids are in uniaxial nematic ( un ), d $ _ { 2 } $ biaxial nematic ( bn ), or d $ _ { 4 } $ bn phase, depending on the strength of magnetic fields from small to large. we suppose a neutron $ ^ { 3 } p _ { 2 } $ superfluid in a ball with a spherical boundary. adopting a suitable boundary condition for $ ^ { 3 } p _ { 2 } $ condensates, we solve the ginzburg - landau equation to find several surface properties for the neutron $ ^ { 3 } p _ { 2 } $ superfluid. first, the phase on the surface can be different from that of the bulk, and symmetry restoration or breaking occurs in general on the surface. second, the distribution of the surface energy density has an anisotropy depending on the polar angle in the sphere, which may lead to the deformation of the geometrical shape of the surface. third, the order parameter manifold induced on the surface, which is described by two - dimensional vector fields induced on the surface from the condensates, allows topological defects ( vortices ) on the surface, and there must exist such defects even in the ground state thanks to the poincar \ ' { e } - hopf theorem : although the numbers of the vortices and antivortices depend on the bulk phases, the difference between them is topologically invariant ( the euler number $ \ chi = 2 $ ) irrespective of the bulk phases. these vortices, which are not extended to the bulk, are called boojums in the context of liquid crystals and helium - 3 superfluids. the surface properties of the neutron $ ^ { 3 } p _ { 2 } $ superfluid found in this paper may provide us useful information to study neutron stars.
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arxiv:1905.13666
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we generalize the standard hopfield model to the case when a weight is assigned to each input pattern. the weight can be interpreted as the frequency of the pattern occurrence at the input of the network. in the framework of the statistical physics approach we obtain the saddle - point equation allowing us to examine the memory of the network. in the case of unequal weights our model does not lead to the catastrophic destruction of the memory due to its overfilling ( that is typical for the standard hopfield model ). the real memory consists only of the patterns with weights exceeding a critical value that is determined by the weights distribution. we obtain the algorithm allowing us to find this critical value for an arbitrary distribution of the weights, and analyze in detail some particular weights distributions. it is shown that the memory decreases as compared to the case of the standard hopfield model. however, in our model the network can learn online without the catastrophic destruction of the memory.
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arxiv:1205.0908
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we study a system of weakly interacting electrons described by the energy dispersion $ \ xi ( \ mathbf { k } ) = k _ x ^ 2 - k _ y ^ 2 - \ mu $ in two dimensions within a renormalization group approach. this energy dispersion exhibits a neck - narrowing lifshitz transition at the critical chemical potential $ \ mu _ c = 0 $ where a van hove singularity develops. implementing a systematic renormalization group analysis of this system has long been hampered by the appearance of nonlocal terms in the wilsonian effective action. we demonstrate that non - locality at the critical point is intrinsic, and the locality of the effective action can be maintained only away from the critical point. we also point out that it is crucial to introduce a large momentum cutoff to keep locality even away from the critical point. based on a local renormalization group scheme employed near the critical point, we show that, as the energy scale $ e $ is lowered, an attractive four - fermion interaction grows as $ \ log ^ 2 e $ for $ e > \ mu $, whereas it retains the usual bcs growth, $ - \ log e $, for $ e < \ mu $. starting away from the critical point, this fast growth of the pairing interaction suggests that the system becomes unstable toward a superconducting state well before the critical point is reached.
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arxiv:1407.6732
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various x - ray satellites have used the crab as a standard candle to perform their calibrations in the past. the calibration of xmm - newton, however, is independent of the crab nebula, because this object has not been used to adjust spectral calibration issues. in 2004 a number of special observations were performed to measure the spectral parameters and the absolute flux of the crab with xmm - newtons epic - pn ccd camera. we describe the results of the campaign in detail and compare them with data of four current missions ( integral, swift, chandra, rxte ) and numerous previous missions ( rosat, exosat, beppo - sax, asca, ginga, einstein, mir - hexe ).
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arxiv:astro-ph/0508235
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we report on the discovery of a highly luminous, broad absorption line quasar at a redshift of $ z = 3. 87 $ which is positionally coincident, within one arcsecond, with the iras fsc source f08279 + 5255. a chance alignment of the quasar and the iras source is extremely unlikely and we argue that the optical and fir flux are different manifestations of the same object. with an r - band magnitude of 15. 2, and an iras 60 $ \ mum $ flux of $ 0. 51 \ jy $, apm 08279 + 5255 is ( apparently ) easily the most intrinsically luminous object known, with $ l _ { bol } \ sim5 \ times10 ^ { 15 } l _ { \ odot } } $. imaging suggests that gravitational lensing may play a role in amplifying the intrinsic properties of the system. the optical spectrum of the quasar clearly reveals the presence of three potential lensing galaxies, \ mg absorption systems at $ z = 1. 18 $ and $ z = 1. 81 $, and a \ ly absorption system at $ z = 3. 07 $. we estimate the total amplification of the optical component to be $ \ approx40 $, but, due to the larger scale of the emitting region, would expect the infrared amplification to be significantly less. even making the conservative assumption that all wavelengths are amplified by a factor 40, apm 08279 + 5255 still possesses a phenomenal luminosity of $ \ simgt 10 ^ { 14l _ { \ odot } } $, indicating that it belongs to a small, but significant population of high - - redshift, hyperluminous objects with copious infrared emission.
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arxiv:astro-ph/9806171
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