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the fermi surface pockets that lie at the corner of the two - iron brillouin zone in heavily electron - doped iron selenide superconductors are accounted for by an extended hubbard model over the square lattice of iron atoms that includes the principal 3d xz and 3d yz orbitals. at half filling, and in the absence of intra - orbital next - nearest neighbor hopping, perfect nesting between electron - type and hole - type fermi surfaces at the the center and at the corner of the one - iron brillouin zone is revealed. it results in hidden magnetic order in the presence of magnetic frustration within mean field theory. an eliashberg - type calculation that includes spin - fluctuation exchange finds that the fermi surfaces undergo a lifshitz transition to electron / hole fermi surface pockets centered at the corner of the two - iron brillouin zone as on - site repulsion grows strong. in agreement with angle - resolved photoemission spectroscopy on iron selenide high - temperature superconductors, only the two electron - type fermi surface pockets remain after a rigid shift in energy of the renormalized band structure by strong enough electron doping. at the limit of strong on - site repulsion, a spin - wave analysis of the hidden - magnetic - order state finds a " floating ring " of low - energy spin excitations centered at the checkerboard wavenumber ( pi, pi ). this prediction compares favorably with recent observations of low - energy spin resonances around ( pi, pi ) in intercalated iron selenide by inelastic neutron scattering.
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arxiv:1806.09322
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c. j. smyth and later flammang studied the spectrum of the weil height in the field of all totally real numbers, establishing both lower and upper bounds for the limit infimum of the height of all totally real integers and determining isolated values of the height. we remove the hypothesis that we consider only integers and establish an lower bound on the limit infimum of the height for all totally real numbers. our proof relies on a quantitative equidistribution theorem for numbers of small height.
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arxiv:1210.7887
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aims. we aim to study the 250 micron luminosity function ( lf ) down to much fainter luminosities than achieved by previous efforts. methods. we developed a modified stacking method to reconstruct the 250 micron lf using optically selected galaxies from the sdss survey and herschel maps of the gama equatorial fields and stripe 82. our stacking method not only recovers the mean 250 micron luminosities of galaxies that are too faint to be individually detected, but also their underlying distribution functions. results. we find very good agreement with previous measurements in the overlapping luminosity range. more importantly, we are able to derive the lf down to much fainter luminosities ( around 25 times fainter ) than achieved by previous studies. we find strong positive luminosity evolution \ propto ( 1 + z ) ^ 4. 89 \ pm1. 07 and moderate negative density evolution \ propto ( 1 + z ) ^ - 1. 02 \ pm0. 54 over the redshift range z = [ 0. 02, 0. 5 ].
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arxiv:1607.02975
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many high dimensional optimization problems can be reformulated into a problem of finding theoptimal state path under an equivalent state space model setting. in this article, we present a general emulation strategy for developing a state space model whose likelihood function ( or posterior distribution ) shares the same general landscape as the objective function of the original optimization problem. then the solution of the optimization problem is the same as the optimal state path that maximizes the likelihood function or the posterior distribution under the emulated system. to find such an optimal path, we adapt a simulated annealing approach by inserting a temperature control into the emulated dynamic system and propose a novel annealed sequential monte carlo ( smc ) method that effectively generating monte carlo sample paths utilizing samples obtained on the high temperature scale. compared to the vanilla simulated annealing implementation, annealed smc is an iterative algorithm for state space model optimization that directly generates state paths from the equilibrium distributions with a decreasing sequence of temperatures through sequential importance sampling which does not require burn - in or mixing iterations to ensure quasi - equilibrium condition. several applications of state space model emulation and the corresponding annealed smc results are demonstrated.
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arxiv:1911.07172
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magnetohydrodynamic instabilities can be responsible for the formation of structures with various scales in astrophysical jets. we consider the stability properties of jets containing both the azimuthal and axial field of subthermal strength. a magnetic field with complex topology in jets is suggested by theoretical models and is consistent with recent observations. stability is discussed by means of a linear analysis of the ideal magnetohydrodynamic equations. we argue that in azimuthal and axial magnetic fields the jet is always unstable to non - axisymmetric perturbations. stabilization does not occur even if the strengths of these field components are comparable. if the axial field is weaker than the azimuthal one, instability occurs for perturbations with any azimuthal wave number $ m $, and the growth rate reaches a saturation value for low values of $ m $. if the axial field is stronger than the toroidal one, the instability shows for perturbations with relatively high $ m $.
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arxiv:1001.1987
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a new method called " variational sampling " is proposed to estimate integrals under probability distributions that can be evaluated up to a normalizing constant. the key idea is to fit the target distribution with an exponential family model by minimizing a strongly consistent empirical approximation to the kullback - leibler divergence computed using either deterministic or random sampling. it is shown how variational sampling differs conceptually from both quadrature and importance sampling and established that, in the case of random independence sampling, it may have much faster stochastic convergence than importance sampling under mild conditions. the variational sampling implementation presented in this paper requires a rough initial approximation to the target distribution, which may be found, e. g. using the laplace method, and is shown to then have the potential to substantially improve over several existing approximate inference techniques to estimate moments of order up to two of nearly - gaussian distributions, which occur frequently in bayesian analysis. in particular, an application of variational sampling to bayesian logistic regression in moderate dimension is presented.
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arxiv:1105.1508
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general - sum differential games can approximate values solved by hamilton - jacobi - isaacs ( hji ) equations for efficient inference when information is incomplete. however, solving such games through conventional methods encounters the curse of dimensionality ( cod ). physics - informed neural networks ( pinns ) offer a scalable approach to alleviate the cod and approximate values, but there exist convergence issues for value approximations through vanilla pinns when state constraints lead to values with large lipschitz constants, particularly in safety - critical applications. in addition to addressing cod, it is necessary to learn a generalizable value across a parametric space of games, rather than training multiple ones for each specific player - type configuration. to overcome these challenges, we propose a hybrid neural operator ( hno ), which is an operator that can map parameter functions for games to value functions. hno leverages informative supervised data and samples pde - driven data across entire spatial - temporal space for model refinement. we evaluate hno on 9d and 13d scenarios with nonlinear dynamics and state constraints, comparing it against a supervised neural operator ( a variant of deeponet ). under the same computational budget and training data, hno outperforms sno for safety performance. this work provides a step toward scalable and generalizable value function approximation, enabling real - time inference for complex human - robot or multi - agent interactions.
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arxiv:2503.06994
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we propose a dynamic structure of coupled dynamic molecular strings for supercooled small polar molecule liquids and accordingly we obtain the hamiltonian of the rotational degrees of freedom of the system. from the hamiltonian, the strongly correlated supercooled polar liquid state is renormalized to a normal superdipole ( sd ) liquid state. this scenario describes the following main features of the primary or a - relaxation dynamics in supercooled polar liquids : ( 1 ) the average relaxation time evolves from a high temperature arrhenius to a low temperature non - arrhenius or super - arrhenius behavior ; ( 2 ) the relaxation function crosses over from the high temperature exponential to low temperature non - exponential form ; and ( 3 ) the temperature dependence of the relaxation strength shows non - curie features. according to the present model, the crossover phenomena of the first two characteristics arise from the transition between the superdipole gas and the superdipole liquid. the model predictions are quantitatively compared with the experimental results of glycerol, a typical glass - former.
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arxiv:cond-mat/0412308
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quasi - hydrostatic cooling of the intracluster gas is studied. in the quasi - hydrostatic model, work done by gravity on the inflow gas with dp \ neq 0, where p is the gas pressure, is taken into account in the thermal balance. the gas flows in from the outer part so as to compensate the pressure loss of the gas undergoing radiative cooling, but the mass flow is so moderate and smooth that the gas is considered to be quasi - hydrostatic. the temperature of the cooling gas decreases toward the cluster center, but, unlike cooling flows with dp = 0, approaches a constant temperature of \ sim 1 / 3 the temperature of the non - cooling ambient gas. this does not mean that gravitational work cancels out radiative cooling, but means that the temperature of the cooling gas appears to approach a constant value toward the cluster center if the gas maintains the quasi - hydrostatic balance. we discuss the mass flow in quasi - hydrostatic cooling, and compare it with the standard isobaric cooling flow model. we also discuss the implication of \ dot { m } for the standard cooling flow model.
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arxiv:astro-ph/0404217
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we derive determinant expressions for the partition functions of spin - k / 2 vertex models on a finite square lattice with domain wall boundary conditions.
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arxiv:math-ph/0601061
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we analyse the kinematics and chemistry of the bulge stars of two simulated disc galaxies using our chemodynamical galaxy evolution code gcd +. first we compare stars that are born inside the galaxy with those that are born outside the galaxy and are accreted into the centre of the galaxy. stars that originate outside of the bulge are accreted into it early in its formation within 3 gyrs so that these stars have high [ alpha / fe ] as well as having a high total energy reflecting their accretion to the centre of the galaxy. therefore, higher total energy is a good indicator for finding accreted stars. the bulges of the simulated galaxies formed through multiple mergers separated by about a gyr. since [ alpha / fe ] is sensitive to the first few gyrs of star formation history, stars that formed during mergers at different epochs show different [ alpha / fe ]. we show that the [ mg / fe ] against star formation time relation can be very useful to identify a multiple merger bulge formation scenario, provided there is sufficiently good age information available. our simulations also show that stars formed during one of the merger events retain a systematically prograde rotation at the final time. this demonstrates that the orbit of the ancient merger that helped to form the bulge could still remain in the kinematics of bulge stars.
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arxiv:0909.4491
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under a precise genuine nonlinearity assumption we establish the decay of entropy solutions of a multidimensional scalar conservation law with merely continuous flux and with initial data being a sum of periodic function and a function vanishing at infinity ( in the sense of measure ).
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arxiv:2010.08752
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from an analysis of the ionisation energy loss of charged particles selected from a sample of 147926 e + e - - > tau + tau - candidates recorded in the opal detector at e + e - centre - of - mass energies near the z0 resonance, we determine the branching ratios : br ( tau - - > nu _ tau k - pi - pi + ( pi0 ) ) = 0. 343 + - 0. 073 + - 0. 031 % br ( tau - - > nu _ tau k - pi - k + ( pi0 ) ) = 0. 159 + - 0. 053 + - 0. 020 % where the ( pi0 ) notation refers to decay modes with or without an accompanying pizero. the tau - - > nu _ tau k - pi - pi + ( pi0 ) final states occurring through tau - - > nu _ tau k - k _ s ( pi0 ) are treated as background in this analysis. we also examine the resonant structure of tau - - > nu _ tau k - pi - pi + candidates. under the assumption that the resonant structure is dominated by the k _ 1 resonances, we determine the ratio of the br ( tau - - > k _ 1 ( 1270 ) ) to the sum of the brs ( tau - > k _ 1 ( 1270 ) and ( tau - > k _ 1 ( 1400 ) ) to be 0. 71 + - 0. 16 + - 0. 11. in all results, the first uncertainties are statistical and the second are systematic.
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arxiv:hep-ex/9908013
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in the present paper, we propose a new axiomatic approach to nonstandard analysis and its application to the general theory of spatial structures in terms of category theory. our framework is based on the idea of internal set theory, while we make use of an endofunctor $ \ mathcal { u } $ on a topos of sets $ s $ together with a natural transformation $ \ upsilon $, instead of the terms as " standard ", " internal " or " external ". moreover, we propose a general notion of a space called $ \ mathcal { u } $ - space, and the category $ \ mathcal { u } space $ whose objects are $ \ mathcal { u } $ - spaces and morphisms are functions called $ \ mathcal { u } $ - spatial morphisms. the category $ \ mathcal { u } space $, which is shown to be cartesian closed, will give a unified viewpoint toward topological and coarse geometric structure. it will also useful to study symmetries / asymmetries of the systems with infinite degrees of freedom such as quantum fields.
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arxiv:1009.0234
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conventional 2d pose estimation models are constrained by their design to specific object categories. this limits their applicability to predefined objects. to overcome these limitations, category - agnostic pose estimation ( cape ) emerged as a solution. cape aims to facilitate keypoint localization for diverse object categories using a unified model, which can generalize from minimal annotated support images. recent cape works have produced object poses based on arbitrary keypoint definitions annotated on a user - provided support image. our work departs from conventional cape methods, which require a support image, by adopting a text - based approach instead of the support image. specifically, we use a pose - graph, where nodes represent keypoints that are described with text. this representation takes advantage of the abstraction of text descriptions and the structure imposed by the graph. our approach effectively breaks symmetry, preserves structure, and improves occlusion handling. we validate our novel approach using the mp - 100 benchmark, a comprehensive dataset spanning over 100 categories and 18, 000 images. under a 1 - shot setting, our solution achieves a notable performance boost of 1. 07 \ %, establishing a new state - of - the - art for cape. additionally, we enrich the dataset by providing text description annotations, further enhancing its utility for future research.
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arxiv:2406.00384
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( 1998 ). categories for the working mathematician. springer - verlag new york, inc. = = external links = = " universe ", encyclopedia of mathematics, ems press, 2001 [ 1994 ] weisstein, eric w. " universal set ". mathworld.
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https://en.wikipedia.org/wiki/Universe_(mathematics)
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based on high - resolution spectra obtained with the mike spectrograph on the magellan telescopes we present detailed elemental abundances for 20 red giant stars in the outer galactic disk, located at galactocentric distances between 9 and 13 kpc. the outer disk sample is complemented with samples of red giants from the inner galactic disk and the solar neighbourhood, analysed using identical methods. for galactocentric distances beyond 10 kpc, we only find chemical patterns associated with the local thin disk, even for stars far above the galactic plane. our results show that the relative densities of the thick and thin disks are dramatically different from the solar neighbourhood, and we therefore suggest that the radial scale length of the thick disk is much shorter than that of the thin disk. we make a first estimate of the thick disk scale - length of l _ thick = 2. 0 kpc, assuming l _ thin = 3. 8 kpc for the thin disk. we suggest that radial migration may explain the lack of radial age, metallicity, and abundance gradients in the thick disk, possibly also explaining the link between the thick disk and the metal - poor bulge.
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arxiv:1106.1914
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using the properties of the transfer matrix of one - dimensional quantum mechanical systems, we derive a technique to exactly compute the persistent current across a hybrid normal - superconducting - mesoscopic ring pierced by a magnetic flux phi as a single integral of a known function of the system ' s parameters. our approach provides exact results at zero temperature, which can be readily extended to finite temperatures t much below the superconducting gap. we apply our technique to derive the persistent current through p - wave and s - wave superconducting - normal hybrid rings, recovering at once a number of effects such as the crossover in the current periodicity on increasing the size of the ring and the signature of the topological phase transition in the p - wave case. in the limit of a large ring size, resorting to a systematic expansion in inverse powers of the ring length, we derive exact analytic closed - form formulas, applicable to a number of cases of physical interest.
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arxiv:1607.01707
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we study the spectrum of scalar - isoscalar excitations in the color - flavor locked phase of dense quark matter. the sigma meson in this phase appears as a four - quark state ( of diquark and anti - diquark ) with a well - defined mass and extremely small width, as a consequence of it ' s small coupling to two pions. the quark particle / hole degrees of freedom also contribute significantly to the correlator just above the threshold 2 \ delta where \ delta is the superconducting gap.
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arxiv:hep-ph/0209249
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nickel - based superconductors provide a long - awaited experimental platform to explore possible cuprate - like superconductivity. despite similar crystal structure and $ d $ electron filling, these systems exhibit several differences. nickelates are the most polar layered oxide superconductor, raising questions about the interface between substrate and thin film - - thus far the only sample geometry to successfully stabilize superconductivity. we conduct a detailed experimental and theoretical study of the prototypical interface between nd $ _ { 1 - x } $ sr $ _ x $ nio $ _ 2 $ and srtio $ _ 3 $. atomic - resolution electron energy loss spectroscopy in the scanning transmission electron microscope reveals the formation of a single intermediate nd ( ti, ni ) o $ _ 3 $ layer. density functional theory calculations with a hubbard $ u $ term show how the observed structure alleviates the strong polar discontinuity. we explore effects of oxygen occupancy, hole doping, and cation structure to disentangle the contributions of each for reducing interface charge density. resolving the nontrivial interface structure will be instructive for future synthesis of nickelate films on other substrates and in vertical heterostructures.
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arxiv:2201.03613
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let $ \ mathfrak { a }, \ mathfrak { b }, \ mathfrak { e } $ be algebras over a field $ k $. then $ \ mathfrak { e } $ is an extension of $ \ mathfrak { a } $ by $ \ mathfrak { b } $ if $ \ mathfrak { a } $ is an ideal of $ \ mathfrak { e } $ and $ \ mathfrak { b } $ is isomorphic to the quotient algebra $ \ mathfrak { e } / \ mathfrak { a } $. in this paper, by using gr \ " obner - shirshov bases theory for associative ( resp. lie ) algebras, we give complete characterizations of associative ( resp. lie ) algebra extensions of $ \ mathfrak { a } $ by $ \ mathfrak { b } $, where $ \ mathfrak { b } $ is presented by generators and relations.
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arxiv:1603.01454
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in recent years, various services have been provided through high - speed and high - capacity wireless networks on mobile communication devices, necessitating stable communication regardless of indoor or outdoor environments. to achieve stable communication, it is essential to implement proactive measures, such as switching to an alternative path and ensuring data buffering before the communication quality becomes unstable. the technology of wireless link quality estimation ( wlqe ), which predicts the communication quality of wireless networks in advance, plays a crucial role in this context. in this paper, we propose a novel wlqe model for estimating the communication quality of wireless networks by leveraging sequential information. our proposed method is based on long short - term memory ( lstm ), enabling highly accurate estimation by considering the sequential information of link quality. we conducted a comparative evaluation with the conventional model, stacked autoencoder - based link quality estimator ( lqe - sae ), using a dataset recorded in real - world environmental conditions. our lstm - based lqe model demonstrates its superiority, achieving a 4. 0 % higher accuracy and a 4. 6 % higher macro - f1 score than the lqe - sae model in the evaluation.
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arxiv:2410.15357
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we present fits to the broadband photometric spectral energy distributions ( seds ) of 158 eclipsing binaries ( ebs ) in the tycho - 2 catalog. these ebs were selected because they have highly precise stellar radii, effective temperatures, and in many cases metallicities previously determined in the literature, and thus have bolometric luminosities that are typically good to $ \ lesssim $ 10 %. in most cases the available broadband photometry spans a wavelength range 0. 4 - 10 $ \ mu $ m, and in many cases spans 0. 15 - 22 $ \ mu $ m. the resulting sed fits, which have only extinction as a free parameter, provide a virtually model - independent measure of the bolometric flux at earth. the sed fits are satisfactory for 156 of the ebs, for which we achieve typical precisions in the bolometric flux of $ \ approx $ 3 %. combined with the accurately known bolometric luminosity, the result for each eb is a predicted parallax that is typically precise to $ \ lesssim $ 5 %. these predicted parallaxes - - - with typical uncertainties of 200 $ \ mu $ as - - - are 4 - 5 times more precise than those determined by hipparcos for 99 of the ebs in our sample, with which we find excellent agreement. there is no evidence among this sample for significant systematics in the hipparcos parallaxes of the sort that notoriously afflicted the pleiades measurement. the ebs are distributed over the entire sky, span more than 10 mag in brightness, reach distances of more than 5 kpc, and in many cases our predicted parallaxes should also be more precise than those expected from the gaia first data release. the ebs studied here can thus serve as empirical, independent benchmarks for these upcoming fundamental parallax measurements.
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arxiv:1609.02579
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the ginibre ensemble of nonhermitean random hamiltonian matrices $ k $ is considered. each quantum system described by $ k $ is a dissipative system and the eigenenergies $ z _ { i } $ of the hamiltonian are complex - valued random variables. the second difference of complex eigenenergies is viewed as discrete analog of hessian with respect to labelling index. the results are considered in view of wigner and dyson ' s electrostatic analogy. an extension of space of dynamics of random magnitudes is performed by introduction of discrete space of labeling indices.
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arxiv:cond-mat/0212453
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perpendicular magnetic anisotropy ( pma ) is a necessary condition for many spintronic applications like spin - orbit torques switching, logic and memory devices. an important class of magnetic insulators with low gilbert damping at room temperature are iron garnets, which only have a few pma types such as terbium and samarium iron garnet. more and stable pma garnet options are necessary for researchers to be able to investigate new spintronic phenomena. in this study, we predict 20 new substrate / magnetic iron garnet film pairs with stable pma at room temperature. the effective anisotropy energies of 10 different garnet films that are lattice - matched to 5 different commercially available garnet substrates have been calculated using shape, magnetoelastic and magnetocrystalline anisotropy terms. strain type, tensile or compressive depending on substrate choice, as well as the sign and the magnitude of the magnetostriction constants of garnets determine if a garnet film may possess pma. we show the conditions in which samarium, gadolinium, terbium, holmium, dysprosium and thulium garnets may possess pma on the investigated garnet substrate types. guidelines for obtaining garnet films with low damping are presented. new pma garnet films with tunable saturation moment and field may improve spin - orbit torque memory and compensated magnonic thin film devices.
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arxiv:1905.13042
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under assumption of singular behavior of invariant charge alpha _ s ( q ^ 2 ) at q ^ 2 sim 0 and of large q ^ 2 behavior, corresponding to the perturbation theory up to four loops, a procedure is considered of smooth matching the beta - function at a boundary of perturbative and nonperturbative regions. the procedure results in a model for alpha _ s for all q ^ 2 > 0 with dimensionless parameters being fixed and dimensional parameters being expressed in terms of only one quantity lambda _ qcd. the gluon condensate which is defined by the nonperturbative part of the invariant charge is calculated for two variants of ` ` true perturbative ' ' invariant charge, corresponding to freezing option and to analytic one in nonperturbative region. dimensional parameters are fixed by varying normalization condition alpha _ s ( m ^ 2 _ tau ) = 0. 29, 0. 30,..., 0. 36. it is obtained that on the boundary of perturbative region alpha _ 0 = alpha _ s ( q _ 0 ^ 2 ) simeq 0. 44, the procedure results in nonperturbative coulomb component alpha _ coulomb simeq 0. 25, the nonperturbative region scale q _ 0 simeq 1 gev, the model parameter sigma simeq ( 0. 42 gev ) ^ 2 which suits as string tension parameter, the gluon condensate appears to be close for two variants considered, k simeq ( 0. 33 - - 0. 36 gev ) ^ 4 ( for alpha _ s ( m ^ 2 _ tau ) = 0. 33 ).
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arxiv:hep-ph/0411339
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introduction : the paper addresses the challenging problem of predicting the short - term realized volatility of the bitcoin price using order flow information. the inherent stochastic nature and anti - persistence of price pose difficulties in accurate prediction. methods : to address this, we propose a method that transforms order flow data over a fixed time interval ( snapshots ) into images. the order flow includes trade sizes, trade directions, and limit order book, and is mapped into image colour channels. these images are then used to train both a simple 3 - layer convolutional neural network ( cnn ) and more advanced resnet - 18 and convmixer, with additionally supplementing them with hand - crafted features. the models are evaluated against classical garch, multilayer perceptron trained on raw data, and a naive guess method that considers current volatility as a prediction. results : the experiments are conducted using price data from january 2021 and evaluate model performance in terms of root mean square error ( rmspe ). the results show that our order flow representation with a cnn as a predictive model achieves the best performance, with an rmspe of 0. 85 + / - 1. 1 for the model with aggregated features and 1. 0 + / - 1. 4 for the model without feature supplementation. convmixer with feature supplementation follows closely. in comparison, the rmspe for the naive guess method was 1. 4 + / - 3. 0.
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arxiv:2304.02472
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an exact solution for the bulk 5 - dimensional geometry is derived for f ( r ) gravity with non - flat de - sitter 3 - branes located at the $ m _ 4 \ times z _ 2 $ orbifold boundaries. the corresponding form of f ( r ) that leads to such an exact solution of the bulk metric is derived which turns out to have all positive integer powers of r. in such a scenario the stability issue of the modulus ( radion field ) is analyzed critically for different curvature epochs in both einstein and jordan frames. the radion in the effective 4 - d theory exhibits a phantom epoch making this model viable for a non - singular bounce. simultaneous resolution of the gauge hierarchy problem is exhibited through the resulting stable vaue of the radion field in the effective $ 3 + 1 $ dimensional theory.
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arxiv:2108.00370
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this paper deals with adaptive synchronization of chaos in the presence of time - varying communication - delays. we consider two bidirectionally coupled systems that seek to synchronize through a signal that each system sends to the other one and is transmitted with an unknown time - varying delay. we show that an appropriate adaptive strategy can be devised that is successful in dynamically identifying the time - varying delay and in synchronizing the two systems. the performance of our strategy with respect to the choice of the initial conditions and the presence of noise in the communication channels is tested by using numerical simulations. another advantage of our approach is that in addition to estimating the communication - delay, the adaptive strategy could be used to simultaneously identify other parameters, such as e. g., the unknown time - varying amplitude of the received signal.
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arxiv:1109.5126
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supernova remnants ( snrs ) have long been hypothesized as the main source of galactic cosmic rays up to pev energies. some of them have indeed been shown to accelerate protons to tev energies and above. but which of them are indeed efficient accelerators of protons and nuclei? and up to which energies can they accelerate these particles? measurements of non - thermal emission, especially in the x - ray and gamma - ray regimes, are essential to answer these questions. the high - altitude water cherenkov ( hawc ) observatory, surveying the northern tev gamma - ray sky, is currently the most sensitive wide field - of - view survey instrument in the vhe ( very - high - energy, $ > $ 100 gev ) range. with more than three years of data recorded, hawc is ideally suited for an unbiased survey of gamma - ray emission from galactic snrs, particularly at tev energies and above. in this proceeding, i will give an overview of recent measurements of vhe gamma - ray emission from snrs with the hawc observatory. combined with data from other wavelengths, these measurements are used to derive information about the underlying particle populations such as the maximum acceleration energy and whether leptonic or hadronic processes are responsible for the emission.
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arxiv:1907.08575
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we discuss the sensitivity of nucleon properties ( mass, magnetic moments and electromagnetic form factors ) on the variation of the pseudoscalar meson masses in the context of the perturbative chiral quark model. the obtained results are compared to data and other theoretical predictions.
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arxiv:0711.0691
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there are many widely used tools for measuring test - coverage and code - coverage. test coverage is the ratio of requirements or other non - code artifacts covered by a test suite, while code - coverage is the ratio of source code covered by tests. almost all coverage tools show a few certain subset of coverage values, and almost always either test - coverage or code - coverage measures. in a large - scale industrial web - application - testing setting, we were faced with the need to " integrate " several types of coverage data ( including front - end and back - end code coverage with requirements coverage ), and to see all of them " live " as large model - based test suites were running. by being unable to find any off - the - shelf toolset to address the above need, we have developed an open - source test coverage tool, specific for mbt, named mbtcover. in addition to code coverage, the tool measures and reports requirements and model coverage, " live " as a given mbt test suite is executing. in this paper, we present the features of the mbtcover tool and our experience from using it in multiple large test - automation projects in practice. other software test engineers, who conduct web application testing and mbt, may find the tool useful in their projects.
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arxiv:2408.06148
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in an attempt to provide an answer to the increasing criticism against p - values and to bridge the gap between statistical inference and prediction modelling, we introduce the probability of improved prediction ( pip ). in general, the pip is a probabilistic measure for comparing two competing models. three versions of the pip and several estimators are introduced and the relationships between them, p - values and the mean squared error are investigated. the performance of the estimators is assessed in a simulation study. an application shows how the pip can support p - values to strengthen the conclusions or possibly point at issues with e. g. replicability.
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arxiv:2405.17064
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in any cubic polynomial, the average of the slopes at the $ 3 $ roots is the negation of the slope at the average of the roots. in any quartic, the average of the slopes at the $ 4 $ roots is twice the negation of the slope at the average of the roots. we generalize such situations and present a procedure for determining all such relationships for polynomials of any degree. e. g., in any septic $ f $, letting $ \ overline { f } _ n $ denote the mean $ f $ value over all zeroes of the derivative $ f ^ { \ left ( n \ right ) } $, it holds that $ 37 $ $ \ overline { f } _ 1 - 150 $ $ \ overline { f } _ 3 + 200 \, \ overline { f } _ 4 - 135 \, \ overline { f } _ 5 + 48 \, % \ overline { f } _ 6 = 0 $ ; and in any quartic it holds that $ 5 $ $ \ overline { f } _ 1 - 6 $ $ \ overline { f } _ 2 + 1 \, \ overline { f } _ 3 = 0 $. having calculated such relationships in all dimensions up to 40, in all even dimensions there is a single relationship, in all odd dimensions there is a two - dimensional family of relationships. we come upon connections to tchebyshev, bernoulli, \ & euler polynomials, and stirling numbers.
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arxiv:1706.08381
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childhood and adolescent obesity rates are a global concern because obesity is associated with chronic diseases and long - term health risks. artificial intelligence technology has emerged as a promising solution to accurately predict obesity rates and provide personalized feedback to adolescents. this study emphasizes the importance of early identification and prevention of obesity - related health issues. factors such as height, weight, waist circumference, calorie intake, physical activity levels, and other relevant health information need to be considered for developing robust algorithms for obesity rate prediction and delivering personalized feedback. hence, by collecting health datasets from 321 adolescents, we proposed an adolescent obesity prediction system that provides personalized predictions and assists individuals in making informed health decisions. our proposed deep learning framework, deephealthnet, effectively trains the model using data augmentation techniques, even when daily health data are limited, resulting in improved prediction accuracy ( acc : 0. 8842 ). additionally, the study revealed variations in the prediction of the obesity rate between boys ( acc : 0. 9320 ) and girls ( acc : 0. 9163 ), allowing the identification of disparities and the determination of the optimal time to provide feedback. the proposed system shows significant potential in effectively addressing childhood and adolescent obesity.
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arxiv:2308.14657
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anharmonicity and local disorder ( polymorphism ) are ubiquitous in perovskite physics, inducing various phenomena observed in scattering and spectroscopy experiments. several of these phenomena still lack interpretation from first - principles since, hitherto, no approach is available to account for anharmonicity and disorder in electron - phonon couplings. here, relying on the special displacement method, we develop a unified treatment of both and demonstrate that electron - phonon coupling is strongly influenced when we employ polymorphous perovskite networks. we uncover that polymorphism in halide perovskites leads to vibrational dynamics far from the ideal noninteracting phonon picture and drives the gradual change in their band gap around phase transition temperatures. we also clarify that combined band gap corrections arising from disorder, spin - orbit coupling, exchange - correlation functionals of high accuracy, and electron - phonon coupling are all essential. our findings agree with experiments, suggesting that polymorphism is the key to address pending questions on perovskites ' technological applications.
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arxiv:2302.09625
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we explore partitions that lie in the intersection of several sets of classical interest : partitions with parts indivisible by $ m $, appearing fewer than $ m $ times, or differing by less than $ m $. we find results on their behavior and generating functions : more results for those simultaneously regular and distinct, fewest for those distinct and flat. we offer some conjectures in the area.
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arxiv:1911.04755
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our understanding of how visual systems detect, analyze and interpret visual stimuli has advanced greatly. however, the visual systems of all animals do much more ; they enable visual behaviours. how well the visual system performs while interacting with the visual environment and how vision is used in the real world have not been well studied, especially in humans. it has been suggested that comparison is the most primitive of psychophysical tasks. thus, as a probe into these active visual behaviours, we use a same - different task : are two physical 3d objects visually the same? this task seems to be a fundamental cognitive ability. we pose this question to human subjects who are free to move about and examine two real objects in an actual 3d space. past work has dealt solely with a 2d static version of this problem. we have collected detailed, first - of - its - kind data of humans performing a visuospatial task in hundreds of trials. strikingly, humans are remarkably good at this task without any training, with a mean accuracy of 93. 82 %. no learning effect was observed on accuracy after many trials, but some effect was seen for response time, number of fixations and extent of head movement. subjects demonstrated a variety of complex strategies involving a range of movement and eye fixation changes, suggesting that solutions were developed dynamically and tailored to the specific task.
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arxiv:2306.11756
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we show that the secant variety of a linearly normal smooth curve of degree at least 2g + 3 is arithmetically cohen - macaulay, and we use this information to study the graded betti numbers of the secant variety.
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arxiv:0806.3056
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we reinterpret the results of the direct searches for dark matter in terms of milli - interacting dark particles. the model reproduces the positive results from dama / libra and cogent and is consistent with the absence of signal in the xenon100, cdms - ii / ge and lux detectors. dark atoms, interacting with standard atoms through a kinetic mixing between photons and dark photons and a mass mixing of { \ sigma } mesons with dark scalars, diffuse elastically in terrestrial matter where they deposit all their energy. reaching underground detectors through gravity at thermal energies, they form bound states with nuclei of the active medium by radiative capture, which causes the emission of photons that produce the observed signals. the parameter space of the model is explored and regions reproducing the results at the 2 { \ sigma } level are obtained for each experiment.
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arxiv:1401.5243
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we consider the possibility of having a large branching ratio for the decay $ b \ to s g $ coming from an enhanced wilson coefficient of the chromomagnetic dipole operator. we show that values of $ br ( b \ to s g ) $ up to $ \ sim 10 \ % $ or more are compatible with the constraints coming from the cleo experimental results on $ br ( b \ to x _ s \ gamma ) $ and $ br ( b \ to x _ s \ phi ) $. such large values can reconcile the predictions of both the semileptonic branching ratio and the charm counting with the present experimental results. we also discuss a supersymmetric model with gluino - mediated flavour violations, which can account for such large values of $ br ( b \ to s g ) $.
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arxiv:hep-ph/9604438
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the unimodular theory of gravity is an alternative perspective to traditional einstein ' s general relativity and opens new possibilities for exploring its implications in cosmology. in this paper, we investigate the unimodular gravity ( ug ) with the latest cosmological data from the pantheon sample of type ia supernovae ( sn ), baryon acoustic oscillations ( bao ), and the observational h ( z ) data from differential age method ( da ). we consider a model consisting of a generalized cosmological constant with radiation and dark matter. the considered theory respects only unimodular coordinate transformations. we fit our model with low - redshift data from sn and da and determine the value of parameter $ \ xi $ of the theory. we find the best - fit value of parameter $ \ xi = 6. 23 \ pm 0. 5 $ ; which deviates from 6, for which the theory becomes the standard general theory of relativity. we further study the hubble constant problem by combining the sn and da data with bao data. we observe deviation in the value of $ h _ 0 $ from the standard $ \ lambda $ cdm model. we obtain $ h _ 0 $ as $ 70. 7 \ pm 4. 1 \ \ mbox { km s } ^ { - 1 } \ mbox { mpc } ^ { - 1 } $ and $ 69. 24 \ pm 0. 90 \ \ mbox { km s } ^ { - 1 } \ mbox { mpc } ^ { - 1 } $ from supernovae data and bao data, respectively in unimodular gravity. combining the bao data with sn + da data set, we obtain $ h _ 0 $ as $ 70. 57 \ pm 0. 56 \ \ mbox { km s } ^ { - 1 } \ mbox { mpc } ^ { - 1 } $.
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arxiv:2306.17754
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we prove that if a link admits non - trivial ( 2k + 1 ) - colorings, with prime 2k + 1 > 7, it also admits non - trivial ( 2k + 1 ) - colorings not involving colors 2k, 2k - 1, nor k.
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arxiv:1308.5278
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we report the discovery of 13 new pulsars in the globular cluster ngc 1851 by the trapum large survey project using the meerkat radio telescope. the discoveries consist of six isolated millisecond pulsars ( msps ) and seven binary pulsars, of which six are msps and one is mildly recycled. for all the pulsars, we present the basic kinematic, astrometric, and orbital parameters, where applicable, as well as their polarimetric properties, when these are measurable. two of the binary msps ( psr j0514 - 4002d and psr j0514 - 4002e ) are in wide and extremely eccentric ( e > 0. 7 ) orbits with a heavy white dwarf and a neutron star as their companion, respectively. with these discoveries, ngc 1851 is now tied with m28 as the cluster with the third largest number of known pulsars ( 14 ). its pulsar population shows remarkable similarities with that of m28, terzan 5 and other clusters with comparable structural parameters. the newly - found pulsars are all located in the innermost regions of ngc 1851 and will likely enable, among other things, detailed studies of the cluster structure and dynamics.
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arxiv:2203.12302
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we consider a lebesgue measure preserving map of the 2 - torus, given by the composition of orthogonal tent shaped shears. we establish strong mixing properties with respect to the invariant measure and polynomial decay of correlations for holder observables, making use of results from the chaotic billiards literature. the system serves as a prototype example of piecewise linear maps which sit on the boundary of ergodicity, possessing null measure sets around which mixing is slowed and which birth elliptic islands under certain perturbations.
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arxiv:2303.08515
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in a typical regular expression ( regex ) crossword puzzle, you are given two nonempty lists $ r _ 1, \ ldots, r _ m $ and $ c _ 1, \ ldots, c _ n $ of regular expressions over some alphabet, and your goal is to fill in an $ m \ times n $ grid with letters from that alphabet so that the string formed by the $ i $ th row is in $ l ( r _ i ) $, and the string formed by the $ j $ th column is in $ l ( c _ j ) $, for all $ 1 \ le i \ le m $ and $ 1 \ le j \ le n $. such a grid is a solution to the puzzle. it is known that determining whether a solution exists is np - complete. we consider a number of restrictions and variants to this problem where all the $ r _ i $ are equal to some regular expression $ r $, and all the $ c _ j $ are equal to some regular expression $ c $. we call the solution to such a puzzle an $ ( r, c ) $ - crossword. our main results are the following : 1. there exists a fixed regular expression $ c $ over the alphabet $ \ { 0, 1 \ } $ such that the following problem is np - complete : " given a regular expression $ r $ over $ \ { 0, 1 \ } $ and positive integers $ m $ and $ n $ given in unary, does an $ m \ times n $ $ ( r, c ) $ - crossword exist? " this improves the result mentioned above. 2. the following problem is np - hard : " given a regular expression $ e $ over $ \ { 0, 1 \ } $ and positive integers $ m $ and $ n $ given in unary, does an $ m \ times n $ $ ( e, e ) $ - crossword exist? " 3. there exists a fixed regular expression $ c $ over $ \ { 0, 1 \ } $ such that the following problem is undecidable ( equivalent to the halting problem ) : " given a regular expression $ r $ over $ \ { 0, 1 \ } $, does an $ ( r, c ) $ - crossword exist ( of any size )? " 4. the following problem is undecidable ( equivalent to the halting problem ) : " given a regular expression $ e $ over $ \ { 0, 1 \
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arxiv:1411.5437
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deep neural networks have shown great success in representation learning. however, when learning with noisy labels ( lnl ), they can easily overfit and fail to generalize to new data. this paper introduces a simple and effective method, named learning to bootstrap ( l2b ), which enables models to bootstrap themselves using their own predictions without being adversely affected by erroneous pseudo - labels. it achieves this by dynamically adjusting the importance weight between real observed and generated labels, as well as between different samples through meta - learning. unlike existing instance reweighting methods, the key to our method lies in a new, versatile objective that enables implicit relabeling concurrently, leading to significant improvements without incurring additional costs. l2b offers several benefits over the baseline methods. it yields more robust models that are less susceptible to the impact of noisy labels by guiding the bootstrapping procedure more effectively. it better exploits the valuable information contained in corrupted instances by adapting the weights of both instances and labels. furthermore, l2b is compatible with existing lnl methods and delivers competitive results spanning natural and medical imaging tasks including classification and segmentation under both synthetic and real - world noise. extensive experiments demonstrate that our method effectively mitigates the challenges of noisy labels, often necessitating few to no validation samples, and is well generalized to other tasks such as image segmentation. this not only positions it as a robust complement to existing lnl techniques but also underscores its practical applicability. the code and models are available at https : / / github. com / yuyinzhou / l2b.
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arxiv:2202.04291
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we renormalize the divergences in the energy - momentum tensor of a scalar field that begins its evolution in an effective initial state. the effective initial state is a formalism that encodes the signatures of new physics in the structure of the quantum state of a field ; in an inflationary setting, these signatures could include trans - planckian effects. we treat both the scalar field and gravity equivalently, considering each as a small quantum fluctuation about a spatially independent background. the classical gravitational equations of motion then arise as a tadpole condition on the graviton. the contribution of the scalar field to these equations contains divergences associated with the structure of the effective state. however, these divergences occur only at the initial time, where the state was defined, and they accompany terms depending solely upon the classical gravitational background. we define the renormalization prescription that adds the appropriate counterterms at the initial - time boundary to cancel these divergences, and illustrate it with several examples evaluated at one - loop order.
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arxiv:hep-th/0609002
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in recent years, formal methods of privacy protection such as differential privacy ( dp ), capable of deployment to data - driven tasks such as machine learning ( ml ), have emerged. reconciling large - scale ml with the closed - form reasoning required for the principled analysis of individual privacy loss requires the introduction of new tools for automatic sensitivity analysis and for tracking an individual ' s data and their features through the flow of computation. for this purpose, we introduce a novel \ textit { hybrid } automatic differentiation ( ad ) system which combines the efficiency of reverse - mode ad with an ability to obtain a closed - form expression for any given quantity in the computational graph. this enables modelling the sensitivity of arbitrary differentiable function compositions, such as the training of neural networks on private data. we demonstrate our approach by analysing the individual dp guarantees of statistical database queries. moreover, we investigate the application of our technique to the training of dp neural networks. our approach can enable the principled reasoning about privacy loss in the setting of data processing, and further the development of automatic sensitivity analysis and privacy budgeting systems.
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arxiv:2107.04265
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in this article we deduce necessary and sufficient conditions for the presence of ` conti - type ', highly symmetric, exactly - stress free constructions in the geometrically non - linear, planar $ n $ - well problem, generalising results of [ ckz17 ]. passing to the limit $ n \ rightarrow \ infty $, this allows us to treat solid crystals and nematic elastomer differential inclusions simultaneously. in particular, we recover and generalise ( non - linear ) planar tripole star type deformations which were experimentally observed in [ ma80, ma80a, kk91 ]. further we discuss the corresponding geometrically linearised problem.
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arxiv:1904.08820
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vehicle models have a long history of research and as of today are able to model the involved physics in a reasonable manner. however, each new vehicle has its new characteristics or parameters. the identification of these is the main task of an engineer. to validate whether the correct parameter set has been chosen is a tedious task and often can only be performed by experts. metrics known commonly used in literature are able to compare different results under certain aspects. however, they fail to answer the question : are the models accurate enough? in this article, we propose the usage of a custom metric trained on the knowledge of experts to tackle this problem. our approach involves three main steps : first, the formalized collection of subject matter experts ' opinion on the question : having seen the measurement and simulation time series in comparison, is the model quality sufficient? from this step, we obtain a data set that is able to quantify the sufficiency of a simulation result based on a comparison to corresponding experimental data. in a second step, we compute common model metrics on the measurement and simulation time series and use these model metrics as features to a regression model. third, we fit a regression model to the experts ' opinions. this regression model, i. e., our custom metric, can than predict the sufficiency of a new simulation result and gives a confidence on this prediction.
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arxiv:2412.07521
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we study fourier and laplace transforms for fourier hyperfunctions with values in a complex locally convex hausdorff space. since any hyperfunction with values in a wide class of locally convex hausdorff spaces can be extended to a fourier hyperfunction, this gives simple notions of asymptotic fourier and laplace transforms for vector - valued hyperfunctions, which improves the existing models of komatsu, b \ " aumer, lumer and neubrander and langenbruch.
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arxiv:2104.02682
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let l be an exact lagrangian submanifold inside the cotangent bundle of a closed manifold n. we prove that if n satisfies a mild homotopy assumption then the image of \ pi _ 2 ( l ) in \ pi _ 2 ( n ) has finite index. we make no assumption on the maslov class of l, and we make no orientability assumptions. the homotopy assumption is either that n is simply connected, or more generally that \ pi _ m ( n ) is finitely generated for each m \ geq 2. the result is proved by constructing the novikov homology theory for symplectic cohomology and generalizing viterbo ' s construction of a transfer map between the homologies of the free loopspaces of n and l.
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arxiv:0711.1396
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we describe a d - - brane inflation model which consists of two fractional d3 branes separated on a transverse $ t ^ 2 \ times k3 $. inflation arises due to the resolved orbifold singularity of $ k3 $ which corresponds to an anomalous d - - term on the brane. we show that d - - brane inflation in the bulk corresponds to d - - term inflation on the brane. the inflaton and the trigger field parametrize the interbrane distances on $ t ^ 2 $ an $ k3 $ respectively. after inflation the branes reach a supersymmetric configuration in which they are at the origin of $ t ^ 2 $ but separated along the $ k3 $ directions.
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arxiv:hep-th/0312042
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we propose a random feature model for approximating high - dimensional sparse additive functions called the hard - ridge random feature expansion method ( harfe ). this method utilizes a hard - thresholding pursuit - based algorithm applied to the sparse ridge regression ( srr ) problem to approximate the coefficients with respect to the random feature matrix. the srr formulation balances between obtaining sparse models that use fewer terms in their representation and ridge - based smoothing that tend to be robust to noise and outliers. in addition, we use a random sparse connectivity pattern in the random feature matrix to match the additive function assumption. we prove that the harfe method is guaranteed to converge with a given error bound depending on the noise and the parameters of the sparse ridge regression model. based on numerical results on synthetic data as well as on real datasets, the harfe approach obtains lower ( or comparable ) error than other state - of - the - art algorithms.
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arxiv:2202.02877
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visual recognition and vision based retrieval of objects from large databases are tasks with a wide spectrum of potential applications. in this paper we propose a novel recognition method from video sequences suitable for retrieval from databases acquired in highly unconstrained conditions e. g. using a mobile consumer - level device such as a phone. on the lowest level, we represent each sequence as a 3d mesh of densely packed local appearance descriptors. while image plane geometry is captured implicitly by a large overlap of neighbouring regions from which the descriptors are extracted, 3d information is extracted by means of a descriptor transition table, learnt from a single sequence for each known gallery object. these allow us to connect local descriptors along the 3rd dimension ( which corresponds to viewpoint changes ), thus resulting in a set of variable length markov chains for each video. the matching of two sets of such chains is formulated as a statistical hypothesis test, whereby a subset of each is chosen to maximize the likelihood that the corresponding video sequences show the same object. the effectiveness of the proposed algorithm is empirically evaluated on the amsterdam library of object images and a new highly challenging video data set acquired using a mobile phone. on both data sets our method is shown to be successful in recognition in the presence of background clutter and large viewpoint changes.
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arxiv:1603.05073
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we perform a comprehensive analysis of complete fusion cross section data with the aim to derive, in a completely data - driven way, a model suitable to predict the integrated cross section of the fusion between light to medium mass nuclei at above barrier energies. to this end, we adopted a novel artificial intelligence approach, based on a hybridization of genetic programming and artificial neural networks, capable to derive an analytical model for the description of experimental data. the approach enables, for the first time, to perform a global search for computationally simple models over several variables and a considerable body of nuclear data. the derived phenomenological formula can serve to reproduce the trend of fusion cross section for a large variety of light to intermediate mass collision systems in an energy domain ranging approximately from the coulomb barrier to the onset of multi - fragmentation phenomena.
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arxiv:2203.10367
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dual kinetic balance ( dkb ) technique was previously developed to eliminate spurious states in the finite - basis - set - based solution of the dirac equation in central fields. in the present paper, it is extended to the dirac equation for systems with axial symmetry. the efficiency of the method is demonstrated by the calculation of the energy spectra of hydrogenlike ions in presence of static uniform electric or magnetic fields. in addition, the dkb basis set is implemented to solve the time - dependent dirac equation making use of the split - operator technique. the excitation and ionization probabilities for the hydrogenlike argon and tin ions exposed to laser pulses are evaluated.
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arxiv:1311.5856
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in this paper, we use geometric tools to study the structure of asymptotic expanders and show that a sequence of asymptotic expanders always admits a " uniform exhaustion by expanders ". it follows that asymptotic expanders cannot be coarsely embedded into any $ l ^ p $ - space, and that asymptotic expanders can be characterised in terms of their uniform roe algebra. moreover, we provide uncountably many new counterexamples to the coarse baum - - connes conjecture. these appear to be the first counterexamples that are not directly constructed by means of spectral gaps. finally, we show that vertex - transitive asymptotic expanders are actually expanders. in particular, this gives a $ c ^ * $ - algebraic characterisation of expanders for vertex - transitive graphs.
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arxiv:1910.13320
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a compact and robust laser system, based on a frequency - doubled telecom laser, providing all the lasers needed for a rubidium cold atom interferometer using optical lattices is presented. thanks to an optical switch at 1. 5 \ mu m and a dual - wavelength second harmonic generation system, only one laser amplifier is needed for all the laser system. our system delivers at 780 nm a power of 900 mw with a detuning of 110 ghz for the optical lattice and a power of 650 mw with an adjustable detuning between 0 and - 1 ghz for the laser cooling, the detection and the raman transitions.
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arxiv:1610.02830
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we present a comparison of the milky way ' s star formation rate ( sfr ) surface density ( $ \ sigma _ { \ rm sfr } $ ) obtained with two independent state - of - the - art observational methods. the first method infers $ \ sigma _ { \ rm sfr } $ from observations of the dust thermal emission from interstellar dust grains in far - infrared wavelengths registered in the herschel infrared galactic plane survey ( hi - gal ). the second method determines $ \ sigma _ { \ rm sfr } $ by modeling the current population of o -, b -, and a - type stars in a 6 kpc $ \ times $ 6 kpc area around the sun. we find an agreement between the two methods within a factor of two for the mean sfrs and the sfr surface density profiles. given the broad differences between the observational techniques and the independent assumptions in the methods for computing the sfrs, this agreement constitutes a significant advance in our understanding of the star formation of our galaxy and implies that the local sfr has been roughly constant over the past 10 \, myr.
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arxiv:2308.01330
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the wealth of data being gathered about humans and their surroundings drives new machine learning applications in various fields. consequently, more and more often, classifiers are trained using not only numerical data but also complex data objects. for example, multi - omics analyses attempt to combine numerical descriptions with distributions, time series data, discrete sequences, and graphs. such integration of data from different domains requires either omitting some of the data, creating separate models for different formats, or simplifying some of the data to adhere to a shared scale and format, all of which can hinder predictive performance. in this paper, we propose a classification method capable of handling datasets with features of arbitrary data types while retaining each feature ' s characteristic. the proposed algorithm, called random similarity forest, uses multiple domain - specific distance measures to combine the predictive performance of random forests with the flexibility of similarity forests. we show that random similarity forests are on par with random forests on numerical data and outperform them on datasets from complex or mixed data domains. our results highlight the applicability of random similarity forests to noisy, multi - source datasets that are becoming ubiquitous in high - impact life science projects.
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arxiv:2204.05389
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modern machine learning increasingly requires training on a large collection of data from multiple sources, not all of which can be trusted. a particularly concerning scenario is when a small fraction of poisoned data changes the behavior of the trained model when triggered by an attacker - specified watermark. such a compromised model will be deployed unnoticed as the model is accurate otherwise. there have been promising attempts to use the intermediate representations of such a model to separate corrupted examples from clean ones. however, these defenses work only when a certain spectral signature of the poisoned examples is large enough for detection. there is a wide range of attacks that cannot be protected against by the existing defenses. we propose a novel defense algorithm using robust covariance estimation to amplify the spectral signature of corrupted data. this defense provides a clean model, completely removing the backdoor, even in regimes where previous methods have no hope of detecting the poisoned examples. code and pre - trained models are available at https : / / github. com / sewoonglab / spectre - defense.
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arxiv:2104.11315
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we investigate theoretically the anisotropic electronic and optical behaviors of a monolayer black phosphorus ( phosphorene ) modulated by periodic potential superlattices in arbitrary directions. we demonstrate that different strength and orientation of the phosphorene potential superlattice can give rise to distinct energy spectra, i. e., tuning the intrinsic electronic anisotropy. accordingly, the anisotropic effective mass, and optical absorption modulated by superlattice strength and orientation are addressed systematically. this feature enables tuning capability more than one order of magnitude in the optical absorption spectrum. our findings should be useful in building phosphorene optical and ( opto ) electronic devices by applying external potential superlattice.
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arxiv:1908.04199
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we consider $ \ alpha $ - $ t _ 3 $ lattice illuminated by intense circularly polarized radiation in terahertz regime. we present quasienergy band structure, time - averaged energy spectrum and time - averaged density of states of $ \ alpha $ - $ t _ 3 $ lattice by solving the floquet hamiltonian numerically. we obtain exact analytical expressions of the quasienergies at the dirac points for all values of $ \ alpha $ and field strength. we find that the quasienergy band gaps at the dirac point decrease with increase of $ \ alpha $. approximate forms of quasienergy and band gaps at single and multi - photon resonant points are derived using rotating wave approximation. the expressions reveal a stark dependence of quasienergy on the berry phase of the charge carrier. the quasi energy flat band remains unaltered in presence of radiation for dice lattice ( $ \ alpha = 1 $ ). however, it acquires a dispersion in and around the dirac and even - photon resonant points when $ 0 < \ alpha < 1 $. the valley degeneracy and electron - hole symmetry in the quasienergy spectrum are broken for $ 0 < \ alpha < 1 $. unlike graphene, the mean energy follows closely the linear dispersion of the dirac cones till near the single - photon resonant point in dice lattice. there are additional peaks in the time - averaged density of states at the dirac point for $ 0 < \ alpha \ leq 1 $.
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arxiv:1805.10866
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we establish a one - to - one correspondence between a class of strictly almost k \ " ahler metrics on the one hand, and lorentzian pp - wave spacetimes on the other ; the latter metrics are well known in general relativity, where they model radiation propagating at the speed of light. specifically, we construct families of complete almost k \ " ahler metrics by deforming pp - waves via their propagation wave vector. the almost k \ " ahler metrics we obtain exist in all dimensions $ 2n \ geq 4 $, and are defined on both $ \ mathbb { r } ^ { 2n } $ and $ \ mathbb { s } ^ 1 \ times \ mathbb { s } ^ 1 \ times m $, where $ m $ is any closed almost k \ " ahler manifold ; they are not warped products, they include noncompact examples with constant negative scalar curvature, and all of them have the property that their fundamental 2 - forms are also co - closed with respect to the lorentzian pp - wave metric. finally, we further deepen this relationship between almost k \ " ahler and lorentzian geometry by utilizing penrose ' s " plane wave limit, " by which every spacetime has, locally, a pp - wave metric as a limit : using penrose ' s construction, we show that in all dimensions $ 2n \ geq 4 $, every lorentzian metric admits, locally, an almost k \ " ahler metric of this form as a limit.
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arxiv:2203.02825
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when a chromophore interacts with titrable molecular sites, the modeling of its photophysical properties requires to take into account all their possible protonation states. we have developed a multi - scale protocol, based on constant - ph molecular dynamics simulations coupled to qm / mm excitation energy calculations, aimed at sampling both the phase space and protonation state space of a short polypeptide featuring a tyrosine - - tryptophan dyad interacting with two aspartic acid residues. we show that such a protocol is accurate enough to reproduce the tyrosine uv absorption spectrum at both acidic and basic ph. moreover, it is confirmed that uv - induced radical tryptophan is reduced thanks to an electron transfer from tyrosine, ultimately explaining the complex ph - dependent behavior of the peptide spectrum.
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arxiv:1710.03684
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ovadia and rodriguez - hertz ( neutralized local entropy, arxiv : 2302. 10874 ) defined the neutralized bowen open ball for an autonomous dynamical system on a compact metric space. replacing the usual bowen open ball with neutralized bowen open ball, we introduce the notions of neutralized bowen topological entropy of subsets, neutralized weighted bowen topological entropy of subsets, lower neutralized brin - katok ' s local entropy of borel probability measures, and neutralized katok ' s entropy of borel probability measures for a non - autonomous dynamical system on a compact metric space. then, we establish variational principles for neutralized bowen topological entropy and neutralized weighted bowen topological entropy of non - empty compact subsets in terms of lower neutralized brin - katok ' s local entropy and neutralized katok ' s entropy. in particular, this extends the main result of ( yang, r., chen, e., zhou, x. : variational principle for neutralized bowen topological entropy, arxiv : 2303. 01738v1 ) for autonomous dynamical systems.
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arxiv:2303.10132
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we present an exact model of the detection statistics of a probabilistic source of photon pairs from which a fast, simple and precise method to measure the source ' s brightness and photon channel transmissions is demonstrated. we measure such properties for a source based on spontaneous parametric downconversion in a periodically poled linbo $ _ 3 $ crystal producing pairs at 810 and 1550 nm wavelengths. we further validate the model by comparing the predicted and measured values for the $ g ^ { ( 2 ) } ( 0 ) $ of a heralded single photon source over a wide range of the brightness. our model is of particular use for monitoring and tuning the brightness on demand as required for various quantum communication applications. we comment on its applicability to sources involving spectral and / or spatial filtering.
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arxiv:0808.2674
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in this paper i propose very simple statistical " memory model " of one - dimensional directed polymers which is capable to store and retrieve a given random quenched trajectory. the model is defined in terms of the elastic string hamiltonian with the local attractive potential between the dynamic and the quenched random strings. the average overlap between them is calculated as a function of the temperature and the strength of the attractive potential.
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arxiv:2206.10184
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consider the plane as a checkerboard, with each unit square colored black or white in an arbitrary manner. in a previous paper we showed that for any such coloring there are straight line segments, of arbitrarily large length, such that the difference of their white length minus their black length, in absolute value, is at least the square root of their length, up to a multiplicative constant. for the corresponding " finite " problem ( $ n \ times n $ checkerboard ) we had proved that we can color it in such a way that the above quantity is at most $ c \ sqrt { n \ log n } $, for any placement of the line segment. in this followup we show that it is possible to color the infinite checkerboard with two colors so that for any line segment $ i $ the excess of one color over another is bounded above by $ c _ \ epsilon \ abs { i } ^ { \ frac12 + \ epsilon } $, for any $ \ epsilon > 0 $. we also prove lower bounds for the discrepancy of circular arcs. finally, we make some observations regarding the $ l ^ p $ discrepancies for segments and arcs, $ p < 2 $, for which our $ l ^ 2 $ - based methods fail to give any reasonable estimates.
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arxiv:0811.3005
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we report synchrotron x - ray scattering studies of charge / orbitally ordered ( coo ) nanoclusters in nd $ _ { 0. 7 } $ sr $ _ { 0. 3 } $ mno $ _ 3 $. we find that the coo nanoclusters are strongly suppressed in an applied magnetic field, and that their decreasing concentration follows the field - induced decrease of the sample electrical resistivity. the coo nanoclusters, however, do not completely disappear in the conducting state, suggesting that this state is inhomogeneous and contains an admixture of an insulating phase. similar results were also obtained for the zero - field insulator - metal transition that occurs as temperature is reduced. these observations suggest that these correlated lattice distortions play a key role in the colossal magnetoresistance effect in this prototypical manganite.
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arxiv:cond-mat/0110533
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transformers have rapidly overtaken cnn - based architectures as the new standard in audio classification. transformer - based models, such as the audio spectrogram transformers ( ast ), also inherit the fixed - size input paradigm from cnns. however, this leads to performance degradation for asts in the inference when input lengths vary from the training. this paper introduces an approach that enables the use of variable - length audio inputs with ast models during both training and inference. by employing sequence packing, our method elasticast, accommodates any audio length during training, thereby offering flexibility across all lengths and resolutions at the inference. this flexibility allows elasticast to maintain evaluation capabilities at various lengths or resolutions and achieve similar performance to standard asts trained at specific lengths or resolutions. moreover, experiments demonstrate elasticast ' s better performance when trained and evaluated on native - length audio datasets.
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arxiv:2407.08691
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the brightest giant flare from the soft $ \ gamma $ - ray repeater ( sgr ) 1806 - 20 was detected on 2004 december 27. the isotropic - equivalent energy release of this burst is at least one order of magnitude more energetic than those of the two other sgr giant flares. starting from about one week after the burst, a very bright ( $ \ sim 80 $ mjy ), fading radio afterglow was detected. follow - up observations revealed the multi - frequency light curves of the afterglow and the temporal evolution of the source size. here we show that these observations can be understood in a two - component explosion model. in this model, one component is a relativistic collimated outflow responsible for the initial giant flare and the early afterglow, and another component is a subrelativistic wider outflow responsible for the late afterglow. we also discuss triggering mechanisms of these two components within the framework of the magnetar model.
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arxiv:astro-ph/0507337
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roc curves and cost curves are two popular ways of visualising classifier performance, finding appropriate thresholds according to the operating condition, and deriving useful aggregated measures such as the area under the roc curve ( auc ) or the area under the optimal cost curve. in this note we present some new findings and connections between roc space and cost space, by using the expected loss over a range of operating conditions. in particular, we show that roc curves can be transferred to cost space by means of a very natural way of understanding how thresholds should be chosen, by selecting the threshold such that the proportion of positive predictions equals the operating condition ( either in the form of cost proportion or skew ). we call these new curves { roc cost curves }, and we demonstrate that the expected loss as measured by the area under these curves is linearly related to auc. this opens up a series of new possibilities and clarifies the notion of cost curve and its relation to roc analysis. in addition, we show that for a classifier that assigns the scores in an evenly - spaced way, these curves are equal to the brier curves. as a result, this establishes the first clear connection between auc and the brier score.
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arxiv:1107.5930
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the enormous technological potential accumulated over the past two decades would make it possible to change the operating principles of power systems entirely. the consequent technological evolution is not only affecting the structure of the electricity markets, but also the interactions between transmission system operators ( tsos ) and distribution system operators ( dsos ). new practical solutions are needed to improve the coordination between the grid operators at the national, tsos, and local level, dsos. in this paper, we define the flexibility range of coordination between tsos and dsos. by doing so, we propose an algorithm based on epsilon - constrained methods by means of mathematical programming and power systems principles. we evaluate and compare different classical optimal power flow formulations ( ac - opf, distflow, distflow - socp, and lindistflow ) for building the flexible tso - dso flexible domain. the presented approaches in this paper are analyzed in an ieee 33 - bus test radial distribution system. we show that for this particular problem, the distflow - socp has the worst accuracy, despite the popularity among the academic community of convex relaxation approaches.
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arxiv:2009.02088
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it is well known that the spectral radius of a tree whose maximum degree is $ d $ cannot exceed $ 2 \ sqrt { d - 1 } $. in this paper we derive similar bounds for arbitrary planar graphs and for graphs of bounded genus. it is proved that a the spectral radius $ \ rho ( g ) $ of a planar graph $ g $ of maximum vertex degree $ d \ ge 4 $ satisfies $ \ sqrt { d } \ le \ rho ( g ) \ le \ sqrt { 8d - 16 } + 7. 75 $. this result is best possible up to the additive constant - - we construct an ( infinite ) planar graph of maximum degree $ d $, whose spectral radius is $ \ sqrt { 8d - 16 } $. this generalizes and improves several previous results and solves an open problem proposed by tom hayes. similar bounds are derived for graphs of bounded genus. for every $ k $, these bounds can be improved by excluding $ k _ { 2, k } $ as a subgraph. in particular, the upper bound is strengthened for 5 - connected graphs. all our results hold for finite as well as for infinite graphs. at the end we enhance the graph decomposition method introduced in the first part of the paper and apply it to tessellations of the hyperbolic plane. we derive bounds on the spectral radius that are close to the true value, and even in the simplest case of regular tessellations of type $ \ { p, q \ } $ we derive an essential improvement over known results, obtaining exact estimates in the first order term and non - trivial estimates for the second order asymptotics.
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arxiv:0907.1591
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a common approach for defining a reward function for multi - objective reinforcement learning ( morl ) problems is the weighted sum of the multiple objectives. the weights are then treated as design parameters dependent on the expertise ( and preference ) of the person performing the learning, with the typical result that a new solution is required for any change in these settings. this paper investigates the relationship between the reward function and the optimal value function for morl ; specifically addressing the question of how to approximate the optimal value function well beyond the set of weights for which the optimization problem was actually solved, thereby avoiding the need to recompute for any particular choice. we prove that the value function transforms smoothly given a transformation of weights of the reward function ( and thus a smooth interpolation in the policy space ). a gaussian process is used to obtain a smooth interpolation over the reward function weights of the optimal value function for three well - known examples : gridworld, objectworld and pendulum. the results show that the interpolation can provide very robust values for sample states and action space in discrete and continuous domain problems. significant advantages arise from utilizing this interpolation technique in the domain of autonomous vehicles : easy, instant adaptation of user preferences while driving and true randomization of obstacle vehicle behavior preferences during training.
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arxiv:1909.05004
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in this paper we obtain new sets of equivalents of the fermat - wiles theorem. simultaneously, we obtain also asymptotic connections between the set of dirichlet ' s series, certain segments of the dirichlet ' s sum $ \ mfrak { d } ( x ) $, riemann zeta - function and jacob ' s ladders.
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arxiv:2502.12748
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let g be an orthogonal or symplectic p - adic group ( not necessarily split ) or an inner form of a general linear p - adic group. in a previous paper, it was shown that the bernstein components of the category of smooth representations of g are equivalent to the category of right modules over some hecke algebra with parameters, or more general over the semi - direct product of such an algebra with a finite group algebra. the aim of the present paper is to show that this equivalence preserves the tem - pered spectrum and the discrete series representations.
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arxiv:1112.4330
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we investigate spontaneous global symmetry breaking in the absence of lorentz invariance, and study technical naturalness of nambu - goldstone ( ng ) modes whose dispersion relation exhibits a hierarchy of multicritical phenomena with lifshitz scaling and dynamical exponents $ z > 1 $. for example, we find ng modes with a technically natural quadratic dispersion relation which do not break time reversal symmetry and are associated with a single broken symmetry generator, not a pair. the mechanism is protected by an enhanced ` polynomial shift ' symmetry in the free - field limit.
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arxiv:1308.5967
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we investigate the hydroelastic wake created by a perturbation moving at constant speed along a thin elastic sheet floating at the surface of deep water. using a high - resolution cross - correlation imaging technique, we characterize the waves as a function of the perturbation speed, for different sheet thicknesses. the general theoretical expression for the dispersion relation of hydroelastic waves includes three components : gravity, bending and stretching. the bending modulus and the tension in the sheet are independently measured. excellent agreement is found between the experimental data and the theoretical expression.
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arxiv:1806.07472
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transformation of protein 3d structures from their all - atom representation ( aar ) to the double - centroid reduced representation ( dcrr ) is a prerequisite to the implementation of both the tetrahedral three - dimensional search motif ( 3d sm ) method for predicting specific ligand binding sites ( lbs ) in proteins, and the 3d interface search motif tetrahedral pair ( 3d ismtp ) method for predicting binary protein - protein interaction ( ppi ) partners ( reyes, v. m., 2015a & c, 2015b, 2009a, b & c ). here we describe results demonstrating the efficacy of the set of fortran 77 and 90 source codes used in the transformation from aar to dcrr and the implementation of the 3d sm and 3d ismtp methods. precisely, we show here the construction of the 3d sm for the biologically important ligands, gtp and sialic acid, from a training set composed of experimentally solved structures of proteins complexed with the pertinent ligand, and their subsequent use in the screening for potential receptor proteins of the two ligands. we also show here the construction of the 3d ismtp for the binary complexes, rac : p67phox and kap : phospho - cdk2, from a training set composed of the experimentally solved complexes, and their subsequent use in the screening for potential protomers of the two complexes. the 15 fortran programs used in the aar to dcrr transformation and the implementation of the two said methods are : get _ bbn. f, get _ sdc. f, res2cm _ bbn. f, res2cm _ sdc. f, nrst _ ngbr. f, find _ hbonds. f, find _ vdwints. f, find _ clusters. f90, find _ trees. f90, find _ edgenodes. f90, match _ nodes. f, fpbs. f90, gen _ chain _ separ. f, remove _ h _ atoms. f and resd _ num _ reduct. f. two flowcharts - one showing how to implement the tetrahedral 3d sm method to find lbss in proteins, and another how to implement the 3d ismtp method to find binary ppi partners - are presented in our two companion papers ( fig. 2, reyes, v. m., 2015a, fig. 1 & 2, reyes, v. m., 2015c
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arxiv:1512.00003
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we formulate self - consistency equations for the distribution of links in spin models and of plaquettes in gauge theories. this improves upon known mean - field, mean - link, and mean - plaquette approximations in such that we self - consistently determine all moments of the considered variable instead of just the first. we give examples in both abelian and non - abelian cases.
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arxiv:1601.01175
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designing synthetic routes for novel molecules is pivotal in various fields like medicine and chemistry. in this process, researchers need to explore a set of synthetic reactions to transform starting molecules into intermediates step by step until the target novel molecule is obtained. however, designing synthetic routes presents challenges for researchers. first, researchers need to make decisions among numerous possible synthetic reactions at each step, considering various criteria ( e. g., yield, experimental duration, and the count of experimental steps ) to construct the synthetic route. second, they must consider the potential impact of one choice at each step on the overall synthetic route. to address these challenges, we proposed synthlens, a visual analytics system to facilitate the iterative construction of synthetic routes by exploring multiple possibilities for synthetic reactions at each step of construction. specifically, we have introduced a tree - form visualization in synthlens to compare and evaluate all the explored routes at various exploration steps, considering both the exploration step and multiple criteria. our system empowers researchers to consider their construction process comprehensively, guiding them toward promising exploration directions to complete the synthetic route. we validated the usability and effectiveness of synthlens through a quantitative evaluation and expert interviews, highlighting its role in facilitating the design process of synthetic routes. finally, we discussed the insights of synthlens to inspire other multi - criteria decision - making scenarios with visual analytics.
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arxiv:2412.00729
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in this paper, we give a brief survey of recent developments on noether ' s problem and rationality problem for multiplicative invariant fields including author ' s recent papers hoshi [ hos15 ] about noether ' s problem over q, hoshi, kang and kunyavskii [ hkk13 ], chu, hoshi, hu and kang [ chhk15 ], hoshi [ hos16 ] and hoshi, kang and yamasaki [ hky16 ] about noether ' s problem over c, and hoshi, kang and kitayama [ hkk14 ] and hoshi, kang and yamasaki [ hky ] about rationality problem for multiplicative invariant fields.
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arxiv:2010.01517
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on the basis of first - principles gw calculations, we study the quasiparticle properties of the guanine, adenine, cytosine, thymine, and uracil dna and rna nucleobases. beyond standard g0w0 calculations, starting from kohn - sham eigenstates obtained with ( semi ) local functionals, a simple self - consistency on the eigenvalues allows to obtain vertical ionization energies and electron affinities within an average 0. 11 ev and 0. 18 ev error respectively as compared to state - of - the - art coupled - cluster and multi - configurational perturbative quantum chemistry approaches. further, gw calculations predict the correct \ pi - character of the highest occupied state, thanks to several level crossings between density functional and gw calculations. our study is based on a recent gaussian - basis implementation of gw with explicit treatment of dynamical screening through contour deformation techniques.
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arxiv:1101.3738
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we describe a fabrication stackup for digital logic with 16 superconducting nbtin layers, self - shunted a - silicon barrier josephson junctions ( jjs ), and low loss, high - $ \ kappa $ tunable hzo capacitors. the stack enables 400 mjj / cm $ ^ 2 $ device density, efficient routing, and ac power distribution on a resonant network. the materials scale beyond 28nm lithography and are compatible with standard high - temperature cmos processes. we report initial results for two - metal layer nbtin wires with 50nm critical dimension. a semi - ascendance wire - and - via process module using 193i lithography and 50nm critical dimension has shown cross - section uniformity of 1 % = 1s across the 300mm wafer, critical temperature of 12. 5k, and critical current of 0. 1ma at 4. 2k. we also present a new design of the resonant ac power network enabled by nbtin wires and hzo mim capacitors. the design matches the device density and provides a 30 ghz clock with estimated efficiency of up to 90 %. finally, magnetic imaging of patterned nbtin ground planes shows low intrinsic defectivity and consistent trapping of vorteces in 0. 5 mm holes spaced on a 20 $ \ mu $ m x 20 $ \ mu $ m grid.
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arxiv:2303.16792
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we present detailed photo + collisional ionization models and kinematic models of the multi - phase absorbing gas, detected within the hst / cos, hst / stis, and keck / hires spectra of the background quasar ton 153, at 104 kpc along the projected minor axis of a star - forming spiral galaxy ( z = 0. 6610 ). complementary g ' r ' i ' ks photometry and stellar population models indicate that the host galaxy is dominated by a 4 gyr stellar population with slightly greater than solar metallicity and has an estimated log ( m * ) = 11 and a log ( mvir ) = 13. photoionization models of the low ionization absorption, ( mgi, siii, mgii and ciii ) which trace the bulk of the hydrogen, constrain the multi - component gas to be cold ( logt = 3. 8 - 5. 2 ) and metal poor ( - 1. 68 < [ x / h ] < - 1. 64 ). a lagging halo model reproduces the low ionization absorption kinematics, suggesting gas coupled to the disk angular momentum, consistent with cold accretion mode material in simulations. the civ and ovi absorption is best modeled in a separate collisionally ionized metal - poor ( - 2. 50 < [ x / h ] < - 1. 93 ) warm phase with logt = 5. 3. although their kinematics are consistent with a wind model, given the 2 - 2. 5dex difference between the galaxy stellar metallicity and the absorption metallicity indicates the gas cannot arise from galactic winds. we discuss and conclude that although the quasar sight - line passes along the galaxy minor axis at projected distance of 0. 3 virial radii, well inside its virial shock radius, the combination of the relative kinematics, temperatures, and relative metallicities indicated that the multi - phase absorbing gas arises from cold accretion around this massive galaxy. our results appear to contradict recent interpretations that absorption probing the projected minor axis of a galaxy is sampling winds.
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arxiv:1208.4098
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we present new vlbi images of supernova 1986j, taken at 5, 8. 4 and 22 ghz between t = 22 to 25 yr after the explosion. the shell expands as t ^ ( 0. 69 + - 0. 03 ). we estimate the progenitor ' s mass - loss rate at ( 4 ~ 10 ) * 10 ^ - 5 msol / yr ( for v _ w = 10 km / s ). two bright spots are seen in the images. the first, in the northeast, is now fading. the second, very near the center of the projected shell and unique to sn1986j, is still brightening relative to the shell, and now dominates the vlbi images. it is marginally resolved at 22 ghz ( diameter ~ 0. 3 mas ; ~ 5 * 10 ^ 16 cm at 10 mpc ). the integrated vla spectrum of sn1986j shows an inversion point and a high - frequency turnover, both progressing downward in frequency and due to the central bright spot. the optically - thin spectral index of the central bright spot is indistinguishable from that of the shell. the small proper motion of 1500 + - 1500 km / s of the central bright spot is consistent with our previous interpretation of it as being associated with the expected black - hole or neutron - star remnant. now, an alternate scenario seems also plausible, where the central bright spot, like the northeast one, results when the shock front impacts on a condensation within the circumstellar medium ( csm ). the condensation would have to be so dense as to be opaque at cm wavelengths ( ~ 1000x denser than the average corresponding csm ) and fortuitously close to the center of the projected shell. we include a movie of the evolution of sn1986j at 5 ghz from t = 0 to 25 yr.
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arxiv:1002.0304
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we describe explicit presentations of all stable and the first nonstable homotopy groups of the unitary groups. in particular, for each n > = 2 we supply n homotopic maps that each represent the ( n - 1 )! - th power of a suitable generator of pi _ 2n ( u ( n ) ) = z _ { n! }. the product of these n commuting maps is the constant map to the identity matrix.
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arxiv:math/0301192
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mixture - of - experts based large language models ( moe llms ) have shown significant promise in multitask adaptability by dynamically routing inputs to specialized experts. despite their success, the collaborative mechanisms among experts are still not well understood, limiting both the interpretability and optimization of these models. in this paper, we focus on two critical issues : ( 1 ) identifying expert collaboration patterns, and ( 2 ) optimizing moe llms through expert pruning. to address the first issue, we propose a hierarchical sparse dictionary learning ( hsdl ) method that uncovers the collaboration patterns among experts. for the second issue, we introduce the contribution - aware expert pruning ( caep ) algorithm, which effectively prunes low - contribution experts. our extensive experiments demonstrate that expert collaboration patterns are closely linked to specific input types and exhibit semantic significance across various tasks. moreover, pruning experiments show that our approach improves overall performance by 2. 5 \ % on average, outperforming existing methods. these findings offer valuable insights into enhancing the efficiency and interpretability of moe llms, offering a clearer understanding of expert interactions and improving model optimization.
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arxiv:2504.12359
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large - scale models have exhibited remarkable capabilities across diverse domains, including automated medical services and intelligent customer support. however, as most large models are trained on single - modality corpora, enabling them to effectively process and understand multimodal signals remains a significant challenge. current research often focuses on designing task - specific or scenario - specific tuning strategies, which limits the scalability and versatility. to address this limitation, we propose a unified framework that concurrently handles multiple tasks and modalities. in this framework, all modalities and tasks are represented as unified tokens and trained using a single, consistent approach. to enable efficient multitask processing, we introduce a novel tuning strategy termed neural tuning, inspired by the concept of sparse distributed representation in the human brain, where only specific subsets of neurons are activated for each task. furthermore, to advance research in multimodal and multitask learning, we present a new benchmark, mmud, which includes samples annotated with multiple task labels spanning reasoning segmentation, referring segmentation, image captioning, and text - to - image generation. by applying neural tuning to pretrained large models on the mmud benchmark, we demonstrate the ability to handle multiple tasks simultaneously in a streamlined and efficient manner. all models, code, and datasets will be released publicly upon publication, fostering further research and innovation in this field.
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arxiv:2408.03001
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web pages are a valuable source of information for many natural language processing and information retrieval tasks. extracting the main content from those documents is essential for the performance of derived applications. to address this issue, we introduce a novel model that performs sequence labeling to collectively classify all text blocks in an html page as either boilerplate or main content. our method uses a hidden markov model on top of potentials derived from dom tree features using convolutional neural networks. the proposed method sets a new state - of - the - art performance for boilerplate removal on the cleaneval benchmark. as a component of information retrieval pipelines, it improves retrieval performance on the clueweb12 collection.
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arxiv:1801.02607
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we present results on an analysis of the decay constants f _ b and f _ bs with two flavours of sea quark. the calculation has been carried out on 3 different bare gauge couplings and 4 sea quark masses at each gauge coupling, with m _ pi / m _ rho ranging from 0. 8 to 0. 6. we employ the fermilab formalism to perform calculations with heavy quarks whose mass is in the range of the b - quark. a detailed comparison with a quenched calculation using the same action is made to elucidate the effects due to the sea quarks.
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arxiv:hep-lat/9909052
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the reconstruction of a smooth field onto a fixed grid is a necessary step for direct comparisons to various real - world observations. projecting sph data onto a fixed grid becomes challenging in adaptive environments, where some particles may have smoothing lengths far below the grid size, whilst others are resolved by thousands of pixels. in this paper we show how the common approach of treating particles below the grid size as monte carlo tracers of the field leads to significant reconstruction errors, and despite good convergence properties is unacceptable for use in synthetic observations in astrophysics. we propose a new method, where particles smaller than the grid size are ` blitted ' onto the grid using a high - resolution pre - calculated kernel, and those close to the grid size are subsampled, that allows for converged predictions for projected quantities at all grid sizes.
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arxiv:2106.05281
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we report on studies of the sensitivity to extra gauge bosons of the reactions e ^ + e ^ - - > nu nubar gamma and e gamma - > nu q + x to extract discovery limits for w ' ' s. the discovery potential for a w ' is, for some models, comparable to that of the lhc. these processes may be also useful for determining w ' and z ' couplings to fermions which would complement measurements made at the large hadron collider.
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arxiv:hep-ph/0009325
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this paper explores the problem of unknotting closed braids and classical knots in mathematical knot theory. we apply evolutionary computation methods to learn sequences of moves that simplify knot diagrams, and show that this can be effective both when the evolution is carried out for individual knots and when a generic sequence of moves is evolved for a set of knots.
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arxiv:1302.0787
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we show that in the case of unknown { \ em harmonic oscillator coherent states } it is possible to achieve what we call { \ it perfect information cloning }. by this we mean that it is still possible to make arbitrary number of copies of a state which has { \ it exactly } the same information content as the original unknown coherent state. by making use of this { \ it perfect information cloning } it would be possible to estimate the original state through measurements and make arbitrary number of copies of the estimator. we define the notion of a { \ em measurement fidelity }. we show that this information cloning gives rise, in the case of $ 1 \ to n $, to a { \ em distribution } of { \ em measurement fidelities } whose average value is $ { 1 \ over 2 } $ irrespective of the number of copies originally made. generalisations of this to the $ m \ to mn $ case as well as the measurement fidelities for gaussian cloners are also given.
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arxiv:quant-ph/0202020
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this paper presents a novel generative model to synthesize fluid simulations from a set of reduced parameters. a convolutional neural network is trained on a collection of discrete, parameterizable fluid simulation velocity fields. due to the capability of deep learning architectures to learn representative features of the data, our generative model is able to accurately approximate the training data set, while providing plausible interpolated in - betweens. the proposed generative model is optimized for fluids by a novel loss function that guarantees divergence - free velocity fields at all times. in addition, we demonstrate that we can handle complex parameterizations in reduced spaces, and advance simulations in time by integrating in the latent space with a second network. our method models a wide variety of fluid behaviors, thus enabling applications such as fast construction of simulations, interpolation of fluids with different parameters, time re - sampling, latent space simulations, and compression of fluid simulation data. reconstructed velocity fields are generated up to 700x faster than re - simulating the data with the underlying cpu solver, while achieving compression rates of up to 1300x.
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arxiv:1806.02071
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