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we report on the calculation of the neutrinoless double - beta decay nuclear matrix element for 76ge within the framework of the realistic shell model. the effective shell - model hamiltonian and the two - body transition operator describing the decay are derived by way of many - body perturbation theory. particular attention is focused on the role played by the so - called pauli blocking effect in the derivation of the effective operator.
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arxiv:1911.12117
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evalrs aims to bring together practitioners from industry and academia to foster a debate on rounded evaluation of recommender systems, with a focus on real - world impact across a multitude of deployment scenarios. recommender systems are often evaluated only through accuracy metrics, which fall short of fully characterizing their generalization capabilities and miss important aspects, such as fairness, bias, usefulness, informativeness. this workshop builds on the success of last year ' s workshop at cikm, but with a broader scope and an interactive format.
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arxiv:2304.07145
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a flag is a sequence of nested subspaces. flags are ubiquitous in numerical analysis, arising in finite elements, multigrid, spectral, and pseudospectral methods for numerical pde ; they arise in the form of krylov subspaces in matrix computations, and as multiresolution analysis in wavelets constructions. they are common in statistics too - - - principal component, canonical correlation, and correspondence analyses may all be viewed as methods for extracting flags from a data set. the main goal of this article is to develop the tools needed for optimizing over a set of flags, which is a smooth manifold called the flag manifold, and it contains the grassmannian as the simplest special case. we will derive closed - form analytic expressions for various differential geometric objects required for riemannian optimization algorithms on the flag manifold ; introducing various systems of extrinsic coordinates that allow us to parameterize points, metrics, tangent spaces, geodesics, distance, parallel transport, gradients, hessians in terms of matrices and matrix operations ; and thereby permitting us to formulate steepest descent, conjugate gradient, and newton algorithms on the flag manifold using only standard numerical linear algebra.
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arxiv:1907.00949
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we propose proximal backpropagation ( proxprop ) as a novel algorithm that takes implicit instead of explicit gradient steps to update the network parameters during neural network training. our algorithm is motivated by the step size limitation of explicit gradient descent, which poses an impediment for optimization. proxprop is developed from a general point of view on the backpropagation algorithm, currently the most common technique to train neural networks via stochastic gradient descent and variants thereof. specifically, we show that backpropagation of a prediction error is equivalent to sequential gradient descent steps on a quadratic penalty energy, which comprises the network activations as variables of the optimization. we further analyze theoretical properties of proxprop and in particular prove that the algorithm yields a descent direction in parameter space and can therefore be combined with a wide variety of convergent algorithms. finally, we devise an efficient numerical implementation that integrates well with popular deep learning frameworks. we conclude by demonstrating promising numerical results and show that proxprop can be effectively combined with common first order optimizers such as adam.
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arxiv:1706.04638
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gas - phase chemistry at extreme conditions ( low densities and temperatures ) is difficult, so the presence of interstellar grains is especially important for the synthesis of molecules that cannot form in the gas phase. interstellar grains are advocated to enhance the encounter rate of the reactive species on their surfaces and to dissipate the energy excess of largely exothermic reactions, but less is known of their role as chemical catalysts that provide low activation energy pathways with enhanced reaction rates. different materials with catalytic properties are present in interstellar environments, like refractory grains containing space - abundant ( d ) block transition metals. quantum chemical calculations considering extended periodic surfaces were carried out in order to search for the stationary points and transitions states to finally construct the reaction potential energy surfaces. binding energy and kinetic calculations based on the rice ramsperger kassel marcus ( rrkm ) scheme were also performed to evaluate the catalytical capacity of the grain and to allocate those reaction processes within the astrochemical framework. our mechanistic studies demonstrate that astrocatalysis is feasible in astrophysical environments. thermodynamically the proposed process is largely exergonic, but kinetically it shows energy barriers that would need from an energy input in order to go through. the present results can explain the presence of ch3oh in diverse regions where current models fail to reproduce its observational quantity. the evidence of astrocatalysis opens a completely new spectrum of synthetic routes triggering chemical evolution in space. from the mechanistic point of view the formation of methanol catalysed by a single atom of fe0 is feasible ; however, its dependency on the temperature makes the energetics a key issue in this scenario.
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arxiv:2312.06416
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we present results from fitting $ p $ - mode spectra derived from 7 - d segments of sun - as - a - star helioseismic observations from the birmingham solar oscillations network covering 32 yr. the results show a clear dependence of the mode frequencies on solar activity, and the frequency dependence of the sensitivity to activity can also be seen. because we use data segments that cover less than half of a solar rotation, we are able to test for the effect of activity on the solar far side. by fitting with a model that takes into account activity on the far side of the sun, we show that the frequency shifts are sensitive to activity from the whole sun, not just the side facing the observer. our results suggest that there is potential to investigate activity - related asteroseismic frequency shifts in solar - like oscillators using short time series of observations.
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arxiv:2501.08190
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quantum discord, and a number of related indicators, are currently raising a relentless interest as a novel paradigm of non - classical correlations beyond entanglement. beside merely fundamental aspects, various works have shown that discord is a valuable - - so far largely unexplored - - resource in quantum information processing. along this line, quite a striking scheme is { entanglement activation }. an initial amount of discord between two disentangled parties of a multipartite system affects the dynamics so as to establish entanglement across a bipartition, which would not arise otherwise. to date, such a process was proven to be achievable only dynamically, i. e., with no guarantee of a stationary entanglement throughput in the presence of noise. here, we discover a { \ it discord - activated mechanism yielding steady - state entanglement } production in a realistic continuous - variable setup. this comprises two coupled optomechanical cavities, where the optical modes ( oms ) communicate through a fiber. we first use a simplified model to highlight the creation of steady - state discord between the oms. we show next that such discord improves the level of stationary optomechanical entanglement attainable in the system, making it more robust against temperature and thermal noise.
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arxiv:1306.1142
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we develop a discrete boltzmann - type model that uses dynamics in phase space to describe the behavior of traffic flows. firstly, we model the traffic flow at mesoscopic scale using dynamics in phase space, which is considered as an evolution model in a graph, and we demonstrate the existence of phase transition phenomena through theoretical analysis. secondly, we assumed the density of vehicles in geometric space to be homogeneous and single - peaked, respectively, and performed numerical simulations to obtain the results consistent with experience. according to this model, we can perform effective simulations on the effects played by multiple parameters on the traffic flow.
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arxiv:2311.14235
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we prove that any c ^ { 1 + } transformation, possibly with a ( non - flat ) critical or singular region, admits an invariant probability measure absolutely continuous with respect to any expanding measure whose jacobian satisfies a mild distortion condition. this is an extension to arbitrary dimension of a famous theorem of keller for maps of the interval with negative schwarzian derivative. we also show how to construct an induced markov map f such that every expanding probability of the initial transformation lifts to an invariant probability of f. the induced time is bounded at each point by the corresponding first hyperbolic time ( the first time the dynamics exhibits hyperbolic behavior ). in particular, f may be used to study decay of correlations and others statistical properties of the initial map, relative to any expanding probability.
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arxiv:0811.2545
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the porous pla foams potential for tissue engineering usage are prepared by a modified solvent casting / particulate leaching method with different crystallinity. since in typical method the porogens are solved in the solution and flow with the polymers during the casting and the crystallinity behavior of pla chains in the limited space cannot be tracked, in this work the processing is modified by diffusing the pla solution into a steady salt stack. with a thermal treatment before leaching while maintaining the stable structure of the porogens stack, the crystallinity of porous foams is made possible to control. the characterizations indicate the crystallization of porous foams is in a manner of lower crystallibility than the bulk materials. pores and caves of around 250 { \ mu } m size are obtained in samples with different crystallinity. the macro - structures are not much impaired by the crystallization nevertheless the morphological effect of the heating process is still obvious.
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arxiv:1404.3930
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we present the herschel bright sources ( herbs ) sample, a sample of bright, high - redshift herschel sources detected in the 616. 4 square degree h - atlas survey. the herbs sample contains 209 galaxies, selected with a 500 { \ mu } m flux density greater than 80 mjy and an estimated redshift greater than 2. the sample consists of a combination of hylirgs and lensed ulirgs during the epoch of peak cosmic star formation. in this paper, we present scuba - 2 observations at 850 $ { \ mu } $ m of 189 galaxies of the herbs sample, 152 of these sources were detected. we fit a spectral template to the herschel - spire and 850 $ { \ mu } $ m scuba - 2 flux densities of 22 sources with spectroscopically determined redshifts, using a two - component modified blackbody spectrum as a template. we find a cold - and hot - dust temperature of 21. 29 k and 45. 80 k, a cold - to - hot dust mass ratio of 26. 62 and a $ \ beta $ of 1. 83. the poor quality of the fit suggests that the sample of galaxies is too diverse to be explained by our simple model. comparison of our sample to a galaxy evolution model indicates that the fraction of lenses is high. out of the 152 scuba - 2 detected galaxies, the model predicts 128. 4 $ \ pm $ 2. 1 of those galaxies to be lensed ( 84. 5 % ). the spire 500 $ { \ mu } $ m flux suggests that out of all 209 herbs sources, we expect 158. 1 $ \ pm $ 1. 7 lensed sources, giving a total lensing fraction of 76 per cent.
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arxiv:1709.01514
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we consider the problem of inferring the input and hidden variables of a stochastic multi - layer neural network from an observation of the output. the hidden variables in each layer are represented as matrices. this problem applies to signal recovery via deep generative prior models, multi - task and mixed regression and learning certain classes of two - layer neural networks. a unified approximation algorithm for both map and mmse inference is proposed by extending a recently - developed multi - layer vector approximate message passing ( ml - vamp ) algorithm to handle matrix - valued unknowns. it is shown that the performance of the proposed multi - layer matrix vamp ( ml - mat - vamp ) algorithm can be exactly predicted in a certain random large - system limit, where the dimensions $ n \ times d $ of the unknown quantities grow as $ n \ rightarrow \ infty $ with $ d $ fixed. in the two - layer neural - network learning problem, this scaling corresponds to the case where the number of input features and training samples grow to infinity but the number of hidden nodes stays fixed. the analysis enables a precise prediction of the parameter and test error of the learning.
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arxiv:2001.09396
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the discovery of materials that simultaneously host different phases of matter has often initially confounded, but ultimately enhanced, our basic understanding of the coexisting types of order. the associated intellectual challenges, together with the promise of greater versatility for potential applications, have made such systems a focus of modern materials science. in particular, great efforts have recently been devoted to making semiconductors ferromagnetic and metallic ferromagnets superconducting. here we report the unprecedented observation of a heavily donor - doped ferromagnetic semiconductor, smn, becoming superconducting with ferromagnetism remaining intact. the extremely large exchange splitting of the conduction and valence bands in this material necessitates that the superconducting order hosted by smn is of an unconventional triplet type, most likely exhibiting p - wave symmetry. short range spin fluctuations, which are thought to be the cause of pairing interactions in currently known triplet superconductors, are quenched in smn, suggesting its superconductivity to be the result of phonon - or coulomb - mediated pairing mechanisms. this scenario is further supported by the inferred heavy mass of superconducting charge carriers. the unique near - zero magnetisation associated with the ferromagnetic state in smn further aids its coexistence with superconductivity. presenting this novel material system where semiconducting, ferromagnetic and superconducting properties are combined provides a versatile new laboratory for studying quantum phases of matter. moreover it is a major step towards identifying materials that merge superconductivity and spintronics, urgently needed to enable the design of electronic devices with superior functionality.
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arxiv:1505.03621
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the wmap experiment has revealed an excess of microwave emission from the region around the center of our galaxy. it has been suggested that this signal, known as the ` ` wmap haze ' ', could be synchrotron emission from relativistic electrons and positrons generated in dark matter annihilations. in this letter, we revisit this possibility. we find that the angular distribution of the wmap haze matches the prediction for dark matter annihilations with a cusped density profile, $ \ rho ( r ) \ propto r ^ { - 1. 2 } $ in the inner kiloparsecs. comparing the intensity in different wmap frequency bands, we find that a wide range of possible wimp annihilation modes are consistent with the spectrum of the haze for a wimp with a mass in the 100 gev to multi - tev range. most interestingly, we find that to generate the observed intensity of the haze, the dark matter annihilation cross section is required to be approximately equal to the value needed for a thermal relic, $ \ sigma v \ sim 3 \ times 10 ^ { - 26 } $ cm $ ^ 3 $ / s. no boost factors are required. if dark matter annihilations are in fact responsible for the wmap haze, and the slope of the halo profile continues into the inner galaxy, glast is expected to detect gamma rays from the dark matter annihilations in the galactic center if the wimp mass is less than several hundred gev.
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arxiv:0705.3655
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we extend to finite temperature the fidelity approach to quantum phase transitions ( qpts ). this is done by resorting to the notion of mixed - state fidelity that allows one to compare two density matrices corresponding to two different thermal states. by exploiting the same concept we also propose a finite - temperature generalization of the loschmidt echo. explicit analytical expressions of these quantities are given for a class of quasi - free fermionic hamiltonians. a numerical analysis is performed as well showing that the associated qpts show their signatures in a finite range of temperatures.
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arxiv:quant-ph/0612008
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we interpret the " explicit formulas " in the sense of analytic number theory for the zeta function of an elliptic curve over a finite field as a transversal index theorem on a 3 - dimensional laminated space.
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arxiv:math/0204194
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by considering the fundamental equation $ x = y - y ^ 2 = z - z ^ 3 $, somos conjectured that the hankel determinants for the generating series $ y ( z ) $ are the somos - 4 numbers. we prove this conjecture by using the quadratic transformation for hankel determinants of sulanke and xin.
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arxiv:0712.0933
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a 3d scene graph represents a compact scene model, storing information about the objects and the semantic relationships between them, making its use promising for robotic tasks. when interacting with a user, an embodied intelligent agent should be capable of responding to various queries about the scene formulated in natural language. large language models ( llms ) are beneficial solutions for user - robot interaction due to their natural language understanding and reasoning abilities. recent methods for creating learnable representations of 3d scenes have demonstrated the potential to improve the quality of llms responses by adapting to the 3d world. however, the existing methods do not explicitly utilize information about the semantic relationships between objects, limiting themselves to information about their coordinates. in this work, we propose a method 3dgraphllm for constructing a learnable representation of a 3d scene graph. the learnable representation is used as input for llms to perform 3d vision - language tasks. in our experiments on popular scanrefer, riorefer, multi3drefer, scanqa, sqa3d, and scan2cap datasets, we demonstrate the advantage of this approach over baseline methods that do not use information about the semantic relationships between objects. the code is publicly available at https : / / github. com / cognitiveaisystems / 3dgraphllm.
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arxiv:2412.18450
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we present an original method to estimate the conductivity of a single molecule anchored to nanometric - sized metallic electrodes, using a mechanically controlled break junction ( mcbj ) operated at room temperature in liquid. we record the conductance through the metal / molecules / metal nanocontact while keeping the metallic electrodes at a fixed distance. taking advantage of thermal diffusion and electromigration, we let the contact naturally explore the more stable configurations around a chosen conductance value. the conductance of a single molecule is estimated from a statistical analysis of raw conductance and conductance standard deviation data for molecular contacts containing up to 14 molecules. the single molecule conductance values are interpreted as time - averaged conductance of an ensemble of conformers at thermal equilibrium.
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arxiv:1706.09818
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we consider a counter - adversarial sequential decision - making problem where an agent computes its private belief ( posterior distribution ) of the current state of the world, by filtering private information. according to its private belief, the agent performs an action, which is observed by an adversarial agent. we have recently shown how the adversarial agent can reconstruct the private belief of the decision - making agent via inverse optimization. the main contribution of this paper is a method to obfuscate the private belief of the agent from the adversary, by performing a suboptimal action. the proposed method optimizes the trade - off between obfuscating the private belief and limiting the increase in cost accrued due to taking a suboptimal action. we propose a probabilistic relaxation to obtain a linear optimization problem for solving the trade - off. in numerical examples, we show that the proposed methods enable the agent to obfuscate its private belief without compromising its cost budget.
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arxiv:2004.04119
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machine learning ( ml ) models have become increasingly valuable in weather forecasting, providing forecasts that not only lower computational costs but often match or exceed the accuracy of traditional numerical weather prediction ( nwp ) models. despite their potential, ml models typically suffer from limitations such as coarse temporal resolution, typically 6 hours, and a limited set of meteorological variables, limiting their practical applicability. to overcome these challenges, we introduce fuxi - 2. 0, an advanced ml model that delivers 1 - hourly global weather forecasts and includes a comprehensive set of essential meteorological variables, thereby expanding its utility across various sectors like wind and solar energy, aviation, and marine shipping. our study conducts comparative analyses between ml - based 1 - hourly forecasts and those from the high - resolution forecast ( hres ) of the european centre for medium - range weather forecasts ( ecmwf ) for various practical scenarios. the results demonstrate that fuxi - 2. 0 consistently outperforms ecmwf hres in forecasting key meteorological variables relevant to these sectors. in particular, fuxi - 2. 0 shows superior performance in wind power forecasting compared to ecmwf hres, further validating its efficacy as a reliable tool for scenarios demanding precise weather forecasts. additionally, fuxi - 2. 0 also integrates both atmospheric and oceanic components, representing a significant step forward in the development of coupled atmospheric - ocean models. further comparative analyses reveal that fuxi - 2. 0 provides more accurate forecasts of tropical cyclone intensity than its predecessor, fuxi - 1. 0, suggesting that there are benefits of an atmosphere - ocean coupled model over atmosphere - only models.
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arxiv:2409.07188
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we present a theoretical description and numerical simulations of the superconducting transition in hybrid structures including strong spin - orbit interactions. the spin - orbit coupling is taken to be of rashba type for concreteness, and we allow for an arbitrary magnitude of the spin - orbit strength as well as an arbitrary thickness of the spin - orbit coupled layer. this allows us to make contact with the experimentally relevant case of enhanced interfacial spin - orbit coupling via atomically thin heavy metal layers. we consider both interfacial spin - orbit coupling induced by inversion asymmetry in an s / f - junction, as well as in - plane spin - orbit coupling in the ferromagnetic region of an s / f / s - and an s / f - structure. both the pair amplitudes, local density of states and critical temperature show dependency on the rashba strength and, importantly, the orientation of the exchange field. in general, spin - orbit coupling increases the critical temperature of a proximity system where a magnetic field is present, and enhances the superconducting gap in the density of states. we perform a theoretical derivation which explains these results by the appearance of long - ranged singlet correlations. our results suggest that $ t _ c $ in ballistic spin - orbit coupled superconducting structures may be tuned by using only a single ferromagnetic layer.
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arxiv:1710.03228
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recent experimental progress in magnetic atoms and polar molecules has created the prospect of simulating dipolar hubbard models with off - site interactions. when applied to real - space cylindrical optical lattices, these anisotropic dipole - dipole interactions acquire a tunable spatially - dependent component while they remain translationally - invariant in the axial direction, creating a sublattice structure in the azimuthal direction. we numerically study how the coexistence of these classes of interactions affects the ground state of hardcore dipolar bosons at half - filling in a finite - size cylindrical optical lattice with octagonal rings. when these two interaction classes cooperate, we find a solid state where the density order is determined by the azimuthal sublattice structure and builds smoothly as the interaction strength increases. for dipole polarisations where the axial interactions are sufficiently repulsive, the repulsion competes with the sublattice structure, significantly increasing entanglement and creating two distinct ordered density patterns. the spatially - varying interactions cause the emergence of these ordered states in small lattices as a function of interaction strength to be staggered according to the azimuthal sublattices.
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arxiv:2110.13540
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we carry out adm splitting in the lagrangian formulation and establish a procedure in which ( almost ) all of the unphysical components of the metric are removed by using the 4d diffeomorphism and the measure - zero 3d symmetry. the procedure introduces a constraint that corresponds to the hamiltonian constraint of the hamiltonian formulation, and its solution implies that the 4d dynamics admits an effective description through 3d hypersurface physics. as far as we can see, our procedure implies potential renormalizability of { the adm formulation of } 4d einstein gravity for which a complete gauge - fixing in the adm formulation and hypersurface foliation of geometry are the key elements. if true, this implies that the alleged unrenormalizability of 4d einstein gravity may be due to the presence of the unphysical fields. the procedure can straightforwardly be applied to quantization around a flat background ; the schwarzschild case seems more subtle. we discuss a potential limitation of the procedure when applying it to explicit time - dependent backgrounds.
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arxiv:1404.5066
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we investigate whether gaia can specify the binary fractions of massive stellar populations in the galactic disk through astrometric microlensing. furthermore, we study if some information about their mass distributions can be inferred via this method. in this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the gaia observing strategy by considering ( a ) stellar - mass black holes, ( b ) neutron stars, ( c ) white dwarfs and ( d ) main - sequence stars as microlenses. the gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is $ \ sim 10 - 20 $ per cent. by calculating the optical depth due to the mentioned stellar populations, the number of the binary astrometric microlensing events being observed with gaia with detectable binary signatures, for the binary fraction about 0. 1, is estimated as 6, 11, 77 and 1316 respectively. consequently, gaia can potentially specify the binary fractions of these massive stellar populations. however, the binary fraction of black holes measured with this method has the large uncertainty owing to a low number of the estimated events. knowing the binary fractions in massive stellar populations helps for studying the gravitational waves. moreover, we investigate the number of massive microlenses which gaia specifies their masses through astrometric microlensing of single lenses toward the galactic bulge. the resulted efficiencies of measuring the mass of mentioned populations are 9. 8, 2. 9, 1. 2 and 0. 8 per cent respectively. the number of their astrometric microlensing events being observed in the gaia era in which the lens mass can be inferred with the relative error less than 0. 5 toward the galactic bulge is estimated as 45, 34, 76 and 786 respectively.
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arxiv:1504.02932
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falls have become more frequent in recent years, which has been harmful for senior citizens. therefore detecting falls have become important and several data sets and machine learning model have been introduced related to fall detection. in this project report, a human fall detection method is proposed using a multi modality approach. we used the up - fall detection data set which is collected by dozens of volunteers using different sensors and two cameras. we use wrist sensor with acclerometer data keeping labels to binary classification, namely fall and no fall from the data set. we used fusion of camera and sensor data to increase performance. the experimental results shows that using only wrist data as compared to multi sensor for binary classification did not impact the model prediction performance for fall detection.
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arxiv:2302.00224
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we developed a mathematical model to describe the transmission of new coronavirus in the s \ ~ ao paulo state, brazil. the model divided a community in subpopulations comprised by young and elder persons, in order to take into account higher risk of fatality among elder persons with severe covid - 19. from data collected in the s \ ~ ao paulo state, we estimated the transmission and additional mortality rates, from which we calculated the basic reproduction number r0. from estimated parameters, estimation of the deaths due to covid - 19 was three times lower than those found in literature. considering isolation as a control mechanism, we varied isolation rates of young and elder persons in order to assess their epidemiological impacts. the epidemiological scenarios focused mainly on evaluating the number of severe covid - 19 cases and deaths due to this disease when isolation is introduced in a population.
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arxiv:2004.05715
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we demonstrate the coherent transport of thermal energy in superlattices by introducing a microscopic definition of the phonon coherence length. we demonstrate how to distinguish a coherent transport regime from diffuse interface scattering and discuss how these can be specifically controlled by several physical parameters. our approach provides a convenient framework for the interpretation of previous experiments and thermal conductivity calculations and paves the way for the design of a new class of thermal interface materials.
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arxiv:1311.5045
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we propose two setups for realizing a chiral quantum network, where two - level systems representing the nodes interact via directional emission into discrete waveguides, as introduced in t. ramos et al. [ phys. rev. a 93, 062104 ( 2016 ) ]. the first implementation realizes a spin waveguide via rydberg states in a chain of atoms, whereas the second one realizes a phonon waveguide via the localized vibrations of a string of trapped ions. for both architectures, we show that strong chirality can be obtained by a proper design of synthetic gauge fields in the couplings from the nodes to the waveguide. in the rydberg case, this is achieved via intrinsic spin - orbit coupling in the dipole - dipole interactions, while for the trapped ions it is obtained by engineered sideband transitions. we take long - range couplings into account that appear naturally in these implementations, discuss useful experimental parameters, and analyze potential error sources. finally, we describe effects that can be observed in these implementations within state - of - the - art technology, such as the driven - dissipative formation of entangled dimer states.
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arxiv:1603.09097
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##2 in preparation of their merger into te pukenga = = = nigeria = = = virtually, every state in nigeria has a polytechnic university operated by either the federal or state government. in rivers state for example, there are two state - owned polytechnic universities ; kenule beeson saro - wiwa polytechnic, bori city and the rivers state college of arts and science, port harcourt. the former was established on 13 may 1988 while the latter β though founded in 1984 β was approved by the nbte in 2006. the first private polytechnic university in the state is the eastern polytechnic, established in 2008. = = = pakistan = = = the polytechnic institutes in pakistan offer diploma in engineering spanning three years in different engineering branches. this diploma is known as diploma of associate engineering ( dae ). students are admitted to the diploma program based on their results in the 10th grade standardized exams. the main purpose of the diploma offered in polytechnic institutes is to train people in various trades. these institutes are located throughout pakistan and started in the early 1950s. after successfully completion of diploma at a polytechnic, students can either get employment or enroll in bachelor of technology ( b. tech ) and bachelor of engineering ( be ) degree programs. universities of engineering & technology in pakistan offer undergraduate ( be / bs / bsc engineering ) and postgraduate ( me / ms / msc engineering and phd ) degree programs in engineering. be / bs / bsc engineering is a professional degree in pakistan. it is a four - year full - time program after hssc ( higher secondary school certificate ). = = = palestine = = = university college of applied sciences ( ucas ) is a technical college in gaza founded in 1998. the college offers undergraduate degrees in several unique specializations such as education technology, technological management and planning, and geographic information systems = = = philippines = = = mapua university, the premier engineering school of the philippines. being an internationally accredited engineering school, it consistently tops various board exams for engineering students in the philippines. feu institute of technology, a premier engineering school known for its technological academic teaching and board topnotchers operating under the far eastern university system. mindanao state university β iligan institute of technology, the premier state university in the southern philippines and the science and technology flagship campus of the mindanao state university system ( the second biggest university system in the philippines after the university of the philippines ). technological university of the philippines, the premier state university of technology education in the philippines. technological institute of the philippines, an engineering school with an international accreditation. bicol university
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https://en.wikipedia.org/wiki/Institute_of_technology
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risk management in dynamic decision problems is a primary concern in many fields, including financial investment, autonomous driving, and healthcare. the mean - variance function is one of the most widely used objective functions in risk management due to its simplicity and interpretability. existing algorithms for mean - variance optimization are based on multi - time - scale stochastic approximation, whose learning rate schedules are often hard to tune, and have only asymptotic convergence proof. in this paper, we develop a model - free policy search framework for mean - variance optimization with finite - sample error bound analysis ( to local optima ). our starting point is a reformulation of the original mean - variance function with its fenchel dual, from which we propose a stochastic block coordinate ascent policy search algorithm. both the asymptotic convergence guarantee of the last iteration ' s solution and the convergence rate of the randomly picked solution are provided, and their applicability is demonstrated on several benchmark domains.
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arxiv:1809.02292
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objective : despite numerous studies proposed for audio restoration in the literature, most of them focus on an isolated restoration problem such as denoising or dereverberation, ignoring other artifacts. moreover, assuming a noisy or reverberant environment with limited number of fixed signal - to - distortion ratio ( sdr ) levels is a common practice. however, real - world audio is often corrupted by a blend of artifacts such as reverberation, sensor noise, and background audio mixture with varying types, severities, and duration. in this study, we propose a novel approach for blind restoration of real - world audio signals by operational generative adversarial networks ( op - gans ) with temporal and spectral objective metrics to enhance the quality of restored audio signal regardless of the type and severity of each artifact corrupting it. methods : 1d operational - gans are used with generative neuron model optimized for blind restoration of any corrupted audio signal. results : the proposed approach has been evaluated extensively over the benchmark timit - rar ( speech ) and gtzan - rar ( non - speech ) datasets corrupted with a random blend of artifacts each with a random severity to mimic real - world audio signals. average sdr improvements of over 7. 2 db and 4. 9 db are achieved, respectively, which are substantial when compared with the baseline methods. significance : this is a pioneer study in blind audio restoration with the unique capability of direct ( time - domain ) restoration of real - world audio whilst achieving an unprecedented level of performance for a wide sdr range and artifact types. conclusion : 1d op - gans can achieve robust and computationally effective real - world audio restoration with significantly improved performance. the source codes and the generated real - world audio datasets are shared publicly with the research community in a dedicated github repository1.
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arxiv:2212.14618
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while diffusion models excel at generating high - quality samples, their latent variables typically lack semantic meaning and are not suitable for representation learning. here, we propose infodiffusion, an algorithm that augments diffusion models with low - dimensional latent variables that capture high - level factors of variation in the data. infodiffusion relies on a learning objective regularized with the mutual information between observed and hidden variables, which improves latent space quality and prevents the latents from being ignored by expressive diffusion - based decoders. empirically, we find that infodiffusion learns disentangled and human - interpretable latent representations that are competitive with state - of - the - art generative and contrastive methods, while retaining the high sample quality of diffusion models. our method enables manipulating the attributes of generated images and has the potential to assist tasks that require exploring a learned latent space to generate quality samples, e. g., generative design.
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arxiv:2306.08757
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the accurate estimation of human activity in cities is one of the first steps towards understanding the structure of the urban environment. human activities are highly granular and dynamic in spatial and temporal dimensions. estimating confidence is crucial for decision - making in numerous applications such as urban management, retail, transport planning and emergency management. detecting general trends in the flow of people between spatial locations is neither obvious nor easy due to the high cost of capturing these movements without compromising the privacy of those involved. this research intends to address this problem by examining the movement of people in a smartstreetsensors network at a fine spatial and temporal resolution using a transfer entropy approach.
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arxiv:2501.06316
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there are four puzzling questions about by the magnitudes of neutrino mixings and mass splittings. a brief sketch is given of the various kinds of models of neutrino masses and how they answer these questions. special attention is given to so - called " lopsided " models.
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arxiv:hep-ph/0206085
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this paper deals with the positive mass theorem and the existence of isoperimetric sets on $ 3 $ - manifolds endowed with continuous complete metrics having nonnegative scalar curvature in a suitable weak sense. we prove that if the manifold has an end that is $ c ^ 0 $ - locally asymptotically flat, and the metric is the local uniform limit of smooth metrics with vanishing lower bounds on the scalar curvature outside a compact set, then huisken ' s isoperimetric mass is nonnegative. this addresses a version of a recent conjecture of huisken about positive isoperimetric mass theorems for continuous metrics satisfying $ r _ g \ geq 0 $ in a weak sense. as a consequence, any fill - in of a truncation of a schwarzschild space with negative adm mass has nonnegative isoperimetric mass. moreover, in case the whole manifold is $ c ^ 0 $ - locally asymptotically flat and the metric is the local uniform limit of smooth metrics with vanishing lower bounds on the scalar curvature outside a compact set, we prove that, as a large scale effect, isoperimetric sets with arbitrarily large volume exist.
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arxiv:2403.15972
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while low mass, star forming galaxies are often considered as the primary driver of reionization, their actual contribution to the cosmic ultraviolet background is still uncertain, mostly because the escape fraction of ionizing photons is only poorly constrained. theoretical studies have shown that efficient supernova feedback is a necessary condition to create paths through which ionizing radiation can escape into the intergalactic medium. we investigate the possibility that accreting supermassive black holes in early dwarf galaxies may provide additional feedback and enhance the leakage of ionizing radiation. we use a series of high resolution cosmological radiation hydrodynamics simulations where we isolate the different sources of feedback. we find that supernova feedback prevents the growth of the black hole, thus quenching its associated feedback. even in cases where the black hole can grow, the structure of the interstellar medium is strongly dominated by supernova feedback. we conclude that, in the dwarf galaxy regime, supermassive black holes do not appear to play a significant role in enhancing the escape fraction and in contributing to the early uv background.
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arxiv:1712.05804
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it is hard for us humans to recognize things in nature until we have invented them ourselves. for image - forming optics, nature has made virtually every kind of lens humans have devised. but what about lensless " imaging "? recently, we showed that a bare array of sensors on a curved substrate could achieve resolution not limited by diffraction - without any lens at all provided that the objects imaged conform to our a priori assumptions. is it possible that somewhere in nature we will find this kind of vision system? we think so and provide examples that seem to make no sense whatever unless they are using something like our lensless imaging work.
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arxiv:physics/0703096
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bitcoin is the most successful cryptocurrency so far. this is mainly due to its novel consensus algorithm, which is based on proof - of - work combined with a cryptographically - protected data structure and a rewarding scheme that incentivizes nodes to participate. however, despite its unprecedented success bitcoin suffers from many inefficiencies. for instance, bitcoin ' s consensus mechanism has been proved to be incentive - incompatible, its high reward variance causes centralization, and its hardcoded deflation raises questions about its long - term sustainability. in this work, we revise the bitcoin consensus mechanism by proposing strongchain, a scheme that introduces transparency and incentivizes participants to collaborate rather than to compete. the core design of our protocol is to reflect and utilize the computing power aggregated on the blockchain which is invisible and " wasted " in bitcoin today. introducing relatively easy, although important changes to bitcoin ' s design enables us to improve many crucial aspects of bitcoin - like cryptocurrencies making it more secure, efficient, and profitable for participants. we thoroughly analyze our approach and we present an implementation of strongchain. the obtained results confirm its efficiency, security, and deployability.
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arxiv:1905.09655
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we analyze the thermodynamical behavior of black holes in closed finite boxes. first the black hole mass evolution is analyzed in an initially empty box. using the conservation of the energy and the hawking evaporation flux, we deduce a minimal volume above which one black hole can loss all of its mass to the box, a result which agrees with the previous analysis made by page. we then obtain analogous results using a box initially containing radiation, allowed to be absorbed by the black hole. the equilibrium times and masses are evaluated and their behavior discussed to highlight some interesting features arising. these results are generalized to $ n $ black holes + thermal radiation. using physically simple arguments, we prove that these black holes achieve the same equilibrium masses ( even that the initial masses were different ). the entropy of the system is used to obtain the dependence of the equilibrium mass on the box volume, number of black holes and the initial radiation. the equilibrium mass is shown to be proportional to a { \ it positive } power law of the effective volume ( contrary to naive expectations ), a result explained in terms of the detailed features of the system. the effect of the reflection of the radiation on the box walls which comes back into the black hole is explicitly considered. all these results ( some of them counter - intuitive ) may be useful to formulate alternative problems in thermodynamic courses for graduate and advanced undergraduate students. a handful of them are suggested in the appendix.
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arxiv:gr-qc/0302079
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the purpose of this paper is to study more general real - valued functions of two variables than just metrics on a set x. we concentrate mainly on the classes of distances and almost distances. we also introduce the notion of a bridge on the disjoint union of two sets and show that it induces a symmetric distance on the disjoint union.
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arxiv:2503.13622
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we analyze a sample of $ z $ - dropout galaxies in the candels goods south and uds fields that have been targeted by a dedicated spectroscopic campaign aimed at detecting their ly $ \ alpha $ line. deep irac observations at 3. 6 and 4. 5 $ \ mu $ m are used to determine the strength of optical emission lines affecting these bands at z $ \ sim $ 6. 5 - 6. 9 in order to i ) investigate possible physical differences between ly $ \ alpha $ emitting and non - emitting sources ; ii ) constrain the escape fraction of ionizing photons ; iii ) provide an estimate of the specific star - formation rate at high redshifts. we find evidence of strong [ oiii ] + h $ \ beta $ emission in the average ( stacked ) seds of galaxies both with and without ly $ \ alpha $ emission. the blue irac [ 3. 6 ] - [ 4. 5 ] color of the stack with detected ly $ \ alpha $ line can be converted into a rest - frame equivalent width ew ( [ oiii ] + h $ \ beta $ ) = 1500 $ ^ { + 530 } _ { - 440 } \ aa $ assuming a flat intrinsic stellar continuum. this strong optical line emission enables a first estimate of f $ _ { esc } \ lesssim $ 20 % on the escape fraction of ionizing photons from ly $ \ alpha $ detected objects. the objects with no ly $ \ alpha $ line show less extreme ew ( [ oiii ] + h $ \ beta $ ) = 520 $ ^ { + 170 } _ { - 150 } \ aa $ suggesting different physical conditions of the hii regions with respect to ly $ \ alpha $ - emitting ones, or a larger f $ _ { esc } $. the latter case is consistent with a combined evolution of f $ _ { esc } $ and the neutral hydrogen fraction as an explanation of the lack of bright ly $ \ alpha $ emission at z $ > $ 6. a lower limit on the specific star formation rate, ssfr $ > $ 9. 1 $ gyr ^ { - 1 } $ for $ m _ { star } = 2 \ times 10 ^ 9 m _ { \ odot } $ galaxies at these redshifts can be derived from the spectroscopically confirmed sample.
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arxiv:1703.08986
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we study salt - induced charge overcompensation and charge inversion of flexible polyelectrolytes via computer simulations and demonstrate the importance of ion excluded volume. reentrant condensation takes place when the ion size is comparable to monomer size, and happens in a middle region of salt concentration. in a high - salt region, ions can overcharge a chain near its surface and charge distribution around a chain displays an oscillatory behavior. unambiguous evidence obtained by electrophoresis shows that charge inversion does not necessarily appear with overcharging and occurs when the ion size is not big. these findings suggest a disconnection of resolubilization of polyelectrolyte condensates at high salt concentration with charge inversion.
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arxiv:0804.3201
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the principle of local gauge invariance is applied to fractional wave equations and the interaction term is determined up to order $ o ( \ bar { g } ) $ in the coupling constant $ \ bar { g } $. as a first application, based on the riemann - liouville fractional derivative definition, the fractional zeeman effect is used to reproduce the baryon spectrum accurately. the transformation properties of the non relativistic fractional schr \ " odinger - equation under spatial rotations are investigated and an internal fractional spin is deduced.
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arxiv:0708.2262
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consider two - type linear - fractional branching processes in varying environments with asymptotically constant mean matrices. let $ \ nu $ be the extinction time. under certain conditions, we show that both $ p ( \ nu = n ) $ and $ p ( \ nu > n ) $ are asymptotically the same as some functions of the products of spectral radii of the mean matrices. we also give an example for which $ p ( \ nu = n ) $ decays with various speeds such as $ \ frac { c } { n ( \ log n ) ^ 2 }, $ $ \ frac { c } { n ^ \ beta }, \ beta > 1 $ et al. which are very different from the ones of homogeneous multitype galton - watson processes.
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arxiv:2007.07840
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this paper deals with the following types of problems : assume a banach space $ x $ has some property ( p ). can it be embedded into some banach space $ z $ with a finite dimensional decomposition having property ( p ), or more generally, having a property related to ( p )? secondly, given a class of banach spaces, does there exist a banach space in this class, or in a closely related one, which is universal for this class?
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arxiv:math/0701324
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motivated by the need to localise faults along electrical power lines, this paper adopts a frequency - domain approach to parameter estimation for an infinite - dimensional linear dynamical system with one spatial variable. since the time of the fault is unknown, and voltages and currents are measured at only one end of the line, distance information must be extracted from the post - fault transients. to properly account for high - frequency transient behaviour, the line dynamics is modelled directly by the telegrapher ' s equation, rather than the more commonly used lumped - parameter approximations. first, the governing equations are non - dimensionalised to avoid ill - conditioning. a closed - form expression for the transfer function is then derived. finally, nonlinear least - squares optimisation is employed to search for the fault location. requirements on fault bandwidth, sensor bandwidth and simulation time - step are also presented. the result is a novel end - to - end algorithm for data generation and fault localisation, the effectiveness of which is demonstrated via simulation.
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arxiv:2310.13359
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although the fluctuation - dissipation framework is a first step to get a quantum model for electrical noise, the merging of displacement and conduction currents into the sole current of a series notion like the resistance r ( f ) does not help in it this task. used to handle these currents as orthogonal components in electromagnetic waves, the usage of the impedance z ( jf ) = r ( f ) + jx ( f ) for the noisy device hides the way it interacts with its thermal bath. in contrast to this, the admittance y ( jf ) is a parallel notion directly linked with the aforementioned interaction that has led us to develop a discrete model for current fluctuations where single electrons randomly shuttling between any pair of terminals generate the voltage noise we can measure between them.
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arxiv:1709.06940
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the homomorphic image of a congruence is always a tolerance ( relation ) but, within a given variety, a tolerance is not necessarily obtained this way. by a maltsev - like condition, we characterize varieties whose tolerances are homomorphic images of their congruences ( timc ). as corollaries, we prove that the variety of semilattices, all varieties of lattices, and all varieties of unary algebras have timc. we show that a congruence n - permutable variety has timc if and only if it is congruence permutable, and construct an idempotent variety with a majority term that fails timc.
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arxiv:1204.2228
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we develop an algorithm for computing the weight distribution of a linear $ [ n, k ] $ code over a finite field $ \ mathbb { f } _ q $. we represent the codes by their characteristic vector with respect to a given generator matrix and a special type of a generator matrix of the k - dimensional simplex code. this characteristic vector is the input data of our algorithms. the complexity of the presented algorithms is o ( kq ^ k ).
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arxiv:1809.07090
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the solar atmosphere displays a sharp temperature gradient, starting from spicules in the chromosphere at $ 2 \ times 10 ^ 4 $ k, outward into the corona exceeding $ 10 ^ 6 $ k. plasma turbulence produced by the transverse motion of magnetic fields anchored in the photosphere is likely the energy source producing this gradient. however, very little is known about the turbulent structures near the solar surface. using the highest spatial resolution white - light total solar eclipse image to date, we measure the transverse correlation length at distances ranging from 0. 33 to 9 mm above the solar surface - two orders of magnitude closer than previous estimates. our results show that the turbulence injection scale in the chromosphere is ~ 1. 5 mm, which we associate with the size of granules since they are the only structured features of comparable size. further, the change in perpendicular correlation length with distance from the solar surface exhibits a plateau in the first 4 mm, followed by a rapid increase until 9 mm where it becomes shallower thereafter. we associate this radial gradient with the expansion of the magnetic field in the transition region between the chromosphere and the corona.
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arxiv:2501.00676
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the useful life of electrochemical energy storage ( ees ) is a critical factor to ees planning, operation, and economic assessment. today, systems commonly assume a physical end - of - life criterion, retiring ees when the remaining capacity reaches a threshold below which the ees is of little use because of functionality degradation. here, we propose an economic end of life criterion, where ees is retired when it cannot earn positive net economic benefit in its intended application. this criterion depends on the use case and degradation characteristics of the ees, but is independent of initial capital cost. using an intertemporal operational framework to consider functionality and profitability degradation, our case study shows that the economic end of life could occur significantly faster than the physical end of life. we argue that both criteria should be applied in ees system planning and assessment. we also analyze how r & d efforts should consider cycling capability and calendar degradation rate when considering the economic end - of - life of ees.
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arxiv:1811.08486
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when we have a morphism f : p ^ n - > p ^ n, then we have an inequality \ frac { 1 } { \ deg f } h ( f ( p ) ) + c > h ( p ) which provides a good upper bound of $ h ( p ) $. however, if $ f $ is a rational map, then \ frac { 1 } { \ deg f } h ( f ( p ) ) + c cannot be an upper bound of h ( p ). in this paper, we will define the $ d $ - ratio of a rational map $ f $ which will replace the degree of a morphism in the height inequality of h ( p ).
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arxiv:1002.3357
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operator inference learns low - dimensional dynamical - system models with polynomial nonlinear terms from trajectories of high - dimensional physical systems ( non - intrusive model reduction ). this work focuses on the large class of physical systems that can be well described by models with quadratic nonlinear terms and proposes a regularizer for operator inference that induces a stability bias onto quadratic models. the proposed regularizer is physics informed in the sense that it penalizes quadratic terms with large norms and so explicitly leverages the quadratic model form that is given by the underlying physics. this means that the proposed approach judiciously learns from data and physical insights combined, rather than from either data or physics alone. additionally, a formulation of operator inference is proposed that enforces model constraints for preserving structure such as symmetry and definiteness in the linear terms. numerical results demonstrate that models learned with operator inference and the proposed regularizer and structure preservation are accurate and stable even in cases where using no regularization or tikhonov regularization leads to models that are unstable.
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arxiv:2107.02597
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in this work we map tunnel conductance curves with nanometric spatial resolution, tracking polaronic quasiparticle excitations when cooling across the insulator - to - metal transition in la0. 7ca0. 3mno3 films. in the insulating phase the spectral signature of polarons, a depletion of conductance at low bias flanked by peaks, is detected all over the scanned surface. these features are still observed at the transition and persist on cooling into the metallic phase. polaron - binding energy maps reveal that polarons are not confined to regions embedded in a highly - conducting matrix but are present over the whole field of view both above and below the transition temperature.
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arxiv:cond-mat/0703460
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the current study explores the novel potential of traversable wormhole solutions within the framework of finsler geometry, incorporating conformal symmetry alongside traceless fluid dynamics. using the conformal killing vector approach, we have discussed the wormholes based on traceless fluid within the intriguing framework of finsler geometry. the field equations and the associated conformal factor are obtained specifically under the condition of conformal motion in finsler geometry. furthermore, we have successfully derived and examined the shape function, considering a range of values for the finslerian parameter $ \ lambda $. our investigation extends to fundamental physical characteristics such as proper radial distance, active mass function, and total gravitational energy, aiming to understand their influence on the traversability of the wormhole. the observation of energy condition violations provides evidence for the exotic matter ' s presence near the throat, reinforcing the assertion of the finslerian wormhole ' s traversability.
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arxiv:2403.03931
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we consider a natural, yet seemingly not much studied, extremal problem in bipartite graphs. a bi - hole of size $ t $ in a bipartite graph $ g $ is a copy of $ k _ { t, t } $ in the bipartite complement of $ g $. let $ f ( n, \ delta ) $ be the largest $ k $ for which every $ n \ times n $ bipartite graph with maximum degree $ \ delta $ in one of the parts has a bi - hole of size $ k $. determining $ f ( n, \ delta ) $ is thus the bipartite analogue of finding the largest independent set in graphs with a given number of vertices and bounded maximum degree. our main result determines the asymptotic behavior of $ f ( n, \ delta ) $. more precisely, we show that for large but fixed $ \ delta $ and $ n $ sufficiently large, $ f ( n, \ delta ) = \ theta ( \ frac { \ log \ delta } { \ delta } n ) $. we further address more specific regimes of $ \ delta $, especially when $ \ delta $ is a small fixed constant. in particular, we determine $ f ( n, 2 ) $ exactly and obtain bounds for $ f ( n, 3 ) $, though determining the precise value of $ f ( n, 3 ) $ is still open.
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arxiv:2002.10930
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interstitial defects are inevitably present in doped semiconductors that enable modern - day electronic, optoelectronic or thermoelectric technologies. understanding of stability of interstitials and their bonding mechanisms in the silicon lattice was accomplished only recently with the advent of first - principles modeling techniques, supported by powerful experimental methods. however, much less attention has been paid to the effect of different naturally occurring interstitials on the thermal and electrical properties of silicon. in this work, we present a systematic study of the variability of heat and charge transport properties of bulk silicon, in the presence of randomly distributed interstitial defects ( si, ge, c and li ). we find through atomistic lattice dynamics and molecular dynamics modeling studies that, interstitial defects scatter heat - carrying phonons to suppress thermal transport - 1. 56 % of randomly distributed ge and li interstitials reduce the thermal conductivity of silicon by $ \ sim $ 30 and 34 times, respectively. using first principles density functional theory and semi - classical boltzmann transport theory, we compute electronic transport coefficients of bulk si with 1. 56 % ge, c, si and li interstitials, in hexagonal, tetrahedral, split - interstitial and bond - centered sites. we demonstrate that hexagonal - si and hexagonal - ge interstitials minimally impact charge transport. to complete the study, we predict the thermoelectric property of an experimentally realizable bulk si sample that contains ge interstitials in different symmetry sites. our research establishes a direct relationship between the variability of structures dictated by fabrication processes and heat and charge transport properties of silicon. the relationship provides guidance to accurately estimate performance of si - based materials for various technological applications.
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arxiv:1806.00217
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we calculate the contribution to the muon anomalous magnetic moment hadronic vacuum polarization from { the } connected diagrams of up and down quarks, omitting electromagnetism. we employ qcd gauge - field configurations with dynamical $ u $, $ d $, $ s $, and $ c $ quarks and the physical pion mass, and analyze five ensembles with lattice spacings ranging from $ a \ approx 0. 06 $ to ~ 0. 15 ~ fm. the up - and down - quark masses in our simulations have equal masses $ m _ l $. we obtain, in this world where all pions have the mass of the $ \ pi ^ 0 $, $ 10 ^ { 10 } a _ \ mu ^ { ll } ( { \ rm conn. } ) = 637. 8 \, ( 8. 8 ) $, in agreement with independent lattice - qcd calculations. we then combine this value with published lattice - qcd results for the connected contributions from strange, charm, and bottom quarks, and an estimate of the uncertainty due to the fact that our calculation does not include strong - isospin breaking, electromagnetism, or contributions from quark - disconnected diagrams. our final result for the total $ \ mathcal { o } ( \ alpha ^ 2 ) $ hadronic vacuum polarization to the muon ' s anomalous magnetic moment is ~ $ 10 ^ { 10 } a _ \ mu ^ { \ rm hvp, lo } = 699 ( 15 ) _ { u, d } ( 1 ) _ { s, c, b } $, where the errors are from the light - quark and heavy - quark contributions, respectively. our result agrees with both { \ it ab - initio } lattice - qcd calculations and phenomenological determinations from experimental $ e ^ + e ^ - $ - scattering data. it is $ 1. 3 \ sigma $ below the " no new physics " value of the hadronic - vacuum - polarization contribution inferred from combining the bnl e821 measurement of $ a _ \ mu $ with theoretical calculations of the other contributions.
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arxiv:1902.04223
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to address the issue of engineering professional excellence in the country. the board has been given the responsibility of regulating the activities and conduct of practicing engineers in the united republic of tanzania in accordance with the functions and powers conferred upon it by the act. according to tanzania laws, it is illegal for an engineer to practice or call themself an engineer if not registered with the board. registration with the board is thus a license to practice engineering in united republic of tanzania. = = asia = = = = = bangladesh = = = to be educated in engineering education in bangladesh, one has to study for a long time. this length of time is required because a fashion engineer in bangladesh has to acquire technical education from an early age. technical school & college engineer means skilled in technical education. and to be proficient in technical education, you have to be educated in technical education from childhood. so you have to pass ( 2 years ) secondary and ( 2 years ) higher secondary from technical school & college under bangladesh technical education board. polytechnic / university polytechnics and universities mainly offer engineering degrees. after secondary and higher secondary, one can get admission in polytechnic & university. polytechnic & university institutes offer 4 - year ( dip. engg. ) and bsc. engg degrees. different types of engineering degrees in diploma are electrical engineering, civil engineering, computer engineering, electronic engineering, marine engineering, mechanical engineering, etc. = = = hong kong = = = in hong kong, engineering degree programmes ( 4 - year bachelor ' s degree ) are offered by public universities funded by the university grant committee ( ugc ). there are 94 ugc - funded programmes in engineering and technology offered by city university of hong kong, the chinese university of hong kong, the hong kong polytechnic university, the hong kong university of science and technology, and the university of hong kong. for example, the faculty of engineering of the university of hong kong ( hku ) has five departments providing undergraduate, postgraduate and research degrees in civil engineering, computer science, electrical and electronic engineering, industrial and manufacturing systems engineering, as well as mechanical engineering. all programmes of bachelor of engineering under the joint university programmes admissions system ( jupas ) code 6963 being offered are accredited by the hong kong institution of engineers ( hkie ). with that standing, the professional qualification of hku engineering graduates is mutually recognized by most countries, such as the united states, australia, canada, japan, korea, new zealand, singapore and south africa. applicants with other local / international / national qualifications such as gce a -
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https://en.wikipedia.org/wiki/Engineering_education
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the path - integral formulation of the statistical mechanics of quantum many - body systems is described, with the purpose of introducing practicaltechniques for the simulation of solids. monte carlo and molecular dynamics methods for distinguishable quantum particles are presented, with particular attention to the isothermal - isobaric ensemble. applications of these computational techniques to different types of solids are reviewed, including noble - gas solids ( helium and heavier elements ), group - iv materials ( diamond and elemental semiconductors ), and molecular solids ( with emphasis on hydrogen and ice ). structural, vibrational, and thermodynamic properties of these materials are discussed. applications also include point defects in solids ( structure and diffusion ), as well as nuclear quantum effects in solid surfaces and adsorbates. different phenomena are discussed, as solid - to - solid and orientational phase transitions, rates of quantum processes, classical - to - quantum crossover, and various finite - temperature anharmonic effects ( thermal expansion, isotopic effects, electron - phonon interactions ). nuclear quantum effects are most remarkable in the presence of light atoms, so that especial emphasis is laid on solids containing hydrogen as a constituent element or as an impurity.
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arxiv:1403.2280
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octans is one of the most distant ( $ d \ sim150 $ pc ) young stellar associations of the solar neighbourhood. its age is still poorly constrained in the literature and requires further investigation. we take advantage of the state - of - the - art astrometry delivered by the third data release of the gaia space mission combined with radial velocity measurements obtained from high - resolution spectroscopy to compute the 3d positions and 3d spatial velocities of the stars and derive the dynamical traceback age of the association. we performed an extensive traceback analysis using different subsamples of stars, different metrics to define the size of the association, and different models for the galactic potential to integrate the stellar orbits in the past. we derive a dynamical age of $ 34 ^ { + 2 } _ { - 2 } $ myr that is independent from stellar models and represents the most precise age estimate currently available for the octans association. after correcting the radial velocity of the stars for the effect of gravitational redshift, we obtain a dynamical age of $ 33 ^ { + 3 } _ { - 1 } $ myr, which is in very good agreement with our first solution. this shows that the effect of gravitational redshift is small for such a distant young stellar association. our result is also consistent with the less accurate age estimates obtained in previous studies from lithium depletion ( 30 - 40myr ) and isochrones ( 20 - 30myr ). by integrating the stellar orbits in time, we show that the members of octans and octans - near had different locations in the past, which indicates that the two associations are unrelated despite the close proximity in the sky. our results confirm that it is possible to derive precise dynamical ages via the traceback method for $ \ sim30 $ myr old stellar clusters at about $ \ sim150 $ pc with the same precision level that has been achieved in other studies for young stellar groups within 50pc of the sun.
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arxiv:2406.12686
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the plasma contributing to emission from the sun between the cool chromosphere ( $ \ le 10 ^ 4 $ k ) and hot corona ( $ \ ge 10 ^ 6 $ k ) has been subjected to many different interpretations. here we look at the magnetic structure of this transition region ( tr ) plasma, based upon the implications of clasp2 data of an active region recently published by ishikawa et al., and earlier iris and sdo data of quiet regions. ishikawa et al. found that large areas of sunspot plages are magnetically unipolar as measured in the cores of \ ion { mg } { 2 } resonance lines, formed in the lower transition region under low plasma - $ \ beta $ conditions. here we show that iris images in the line cores have fibrils which well aligned with the overlying coronal loop segments seen in the 171 \ aa { } channel of sdo. when the tr emission in active regions arise from plasma magnetically and thermally connected to the corona, then the line cores can provide the first credible magnetic boundary conditions for force - free calculations extended to the corona. we also re - examine iris images of dynamic tr cool loops previously reported as a major contributor to transition region emission from the quiet sun. dynamic cool loops contribute only a small fraction of the total tr emission from the quiet sun.
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arxiv:2104.07753
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as an edge intelligence algorithm for multi - device collaborative training, federated learning ( fl ) can reduce the communication burden but increase the computing load of wireless devices. in contrast, split learning ( sl ) can reduce the computing load of devices by using model splitting and assignment, but increase the communication burden to transmit intermediate results. in this paper, to exploit the advantages of fl and sl, we propose a hybrid federated split learning ( hfsl ) framework in wireless networks, which combines the multi - worker parallel update of fl and flexible splitting of sl. to reduce the computational idleness in model splitting, we design a parallel computing scheme for model splitting without label sharing, and theoretically analyze the influence of the delayed gradient caused by the scheme on the convergence speed. aiming to obtain the trade - off between the training time and energy consumption, we optimize the splitting decision, the bandwidth and computing resource allocation. the optimization problem is multi - objective, and we thus propose a predictive generative adversarial network ( gan ) - powered multi - objective optimization algorithm to obtain the pareto front of the problem. experimental results show that the proposed algorithm outperforms others in finding pareto optimal solutions, and the solutions of the proposed hfsl dominate the solution of fl.
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arxiv:2209.02428
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the prolongation g ^ { ( k ) } of a linear lie algebra g \ subset gl ( v ) plays an important role in the study of symmetries of g - structures. cartan and kobayashi - nagano have given a complete classification of irreducible linear lie algebras g \ subset gl ( v ) with non - zero prolongations. if g is the lie algebra aut ( \ hat { s } ) of infinitesimal linear automorphisms of a projective variety s \ subset \ bp v, its prolongation g ^ { ( k ) } is related to the symmetries of cone structures, an important example of which is the variety of minimal rational tangents in the study of uniruled projective manifolds. from this perspective, understanding the prolongation aut ( \ hat { s } ) ^ { ( k ) } is useful in questions related to the automorphism groups of uniruled projective manifolds. our main result is a complete classification of irreducible non - degenerate nonsingular variety with non zero prolongations, which can be viewed as a generalization of the result of cartan and kobayashi - nagano. as an application, we show that when $ s $ is linearly normal and sec ( s ) \ neq p ( v ), the blow - up of p ( v ) along s has the target rigidity property, i. e., any deformation of a surjective morphism y \ to bl _ s ( pv ) comes from the automorphisms of bl _ s ( pv ).
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arxiv:1011.4751
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the self - assembly of functionalized ( patchy ) particles with directional interactions into target structures is still a challenge, despite the significant experimental advances on their synthesis. the self - assembly pathways are typically characterized by high energy barriers that hinder the access to stable ( equilibrium ) structures. a possible strategy to tackle this challenge is to perform annealing cycles. by periodically switching on and off the inter - particle bonds, one expects to smooth - out the kinetic pathways and favor the assembly of targeted structures. preliminary results have shown that the efficiency of annealing cycles depends strongly on their frequency. here, we study numerically how this frequency - dependence scales with the strength of the directional interactions ( size of the patch $ \ sigma $ ). we use analytical arguments to show that the scaling results from the statistics of a random walk in configurational space.
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arxiv:1710.02373
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recently, j. d. lawson encouraged the domain theory community to consider the scientific program of developing domain theory in the wider context of $ t _ 0 $ spaces instead of restricting to posets. in this paper, we respond to this calling with an attempt to formulate a topological version of the scott convergence theorem, i. e., an order - theoretic characterisation of those posets for which the scott - convergence $ \ mathcal { s } $ is topological. to do this, we make use of the $ \ mathcal { id } $ replacement principle to create topological analogues of well - known domain - theoretic concepts, e. g., $ \ mathcal { i } $ - continuous spaces correspond to continuous posets, as $ \ mathcal { i } $ - convergence corresponds to $ \ mathcal { s } $ - convergence. in this paper, we consider two novel topological concepts, namely, the $ \ mathcal { i } $ - stable spaces and the $ \ mathcal { di } $ spaces, and as a result we obtain some necessary ( respectively, sufficient ) conditions under which the convergence structure $ \ mathcal { i } $ is topological.
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arxiv:1710.03115
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friction is central to the motion of active ( self - propelled ) objects such as bacteria, animals, and robots. while in a viscous fluid friction is described by stokes ' s law, objects in contact with other solid bodies are often governed by more complex empirical friction laws. here, we study active particles subject to coulomb friction using a combination of active granular experiments and simulations, supported by theoretical predictions. the interplay of friction and activity forces induces a rich behavior resulting in three distinct dynamical regimes. while for low activity, brownian motion is recovered, for large activity we observe a dynamical stop & go regime that continuously switches from diffusion and accelerated motion. for greater activity, we observe a super - mobile dynamical regime characterized by a fully accelerated motion which is described by an anomalous scaling of the diffusion coefficient with the activity. these findings cannot be observed with stokes viscous forces typical of active swimmers but are central in dry active objects.
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arxiv:2404.06615
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having ruled out the possibility that stellar objects are the main contributor of the dark matter embedding galaxies, microlensing experiments cannot exclude the hypothesis that a significant fraction of the milky way dark halo might be made of machos with masses in the range $ 0. 5 - 0. 8 \ msun $. ancient white dwarfs are generally considered the most plausible candidates for such machos. we report the results of a search for such white dwarfs in a proper motion survey covering a 0. 16 sqd field at three epochs at high galactic latitude, and 0. 938 sqd at two epochs at intermediate galactic latitude ( virmos survey ), using the cfh telescope. both surveys are complete to i = 23, with detection efficiency fading to 0 at i = 24. 2. proper motion data are suitable to separate unambiguously halo white dwarfs identified by belonging to a non rotating system. no candidates were found within the colour - magnitude - proper motion volume where such objects can be safely discriminated from any standard population as well as from possible artefacts. in the same volume, we estimate the maximum white dwarf halo fraction compatible with this observation at different significance levels if the halo is at least 14 gigayears old and under different ad hoc initial mass functions. our data alone rules out a halo fraction greater than 14 % at 95 % confidence level. combined with two previous investigations exploring comparable volumes pushes the limit below 4 % ( 95 % confidence level ) or below 1. 3 % ( 64 % confidence ), this implies that if baryonic dark matter is present in galaxy halos, it is not, or it is only marginally in the form of faint hydrogen white dwarfs.
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arxiv:astro-ph/0403543
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the $ c \! p $ asymmetry and branching fraction of the ckm - suppressed decay $ b ^ + \! \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, \ pi ^ + $ are precisely measured relative to the favoured decay $ b ^ + \! \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, k ^ + $, using a sample of proton - proton collision data corresponding to an integrated luminosity of $ 5. 4 ~ \ mathrm { fb } ^ { - 1 } $ recorded at center - of - mass energy of $ 13 ~ \ mathrm { tev } $ during 2016 - - 2018. the results of the $ c \! p $ asymmetry difference and branching fraction ratio are \ begin { align * } \ delta \ mathcal { a } ^ { c \! p } & \ equiv \ mathcal { a } ^ { c \! p } ( b ^ + \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, \ pi ^ + ) - \ mathcal { a } ^ { c \! p } ( b ^ + \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, k ^ + ) = ( 1. 29 \ pm 0. 49 \ pm 0. 08 ) \ times 10 ^ { - 2 }, \ end { align * } \ begin { equation * } \ mathcal { r } _ { \ pi / k } \ equiv \ frac { \ mathcal { b } ( b ^ + \! \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, \ pi ^ + ) } { \ mathcal { b } ( b ^ + \! \ to j \ mskip - 3mu / \ mskip - 2mu \ psi \, k ^ + ) } = ( 3. 852 \ pm 0. 022 \ pm 0. 018 ) \ times 10 ^ { - 2 }. \ end { equation * } where the first uncertainties are statistical and the second systematic. a combination with previous lhcb results based on data collected at $ 7 $ and $ 8 ~ \ mathrm { tev } $ in 2011 and 2012 yields $ \ delta \ mathcal {
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arxiv:2411.12178
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in this article, we introduce a universal simulator covering all regimes of matter wave light - pulse elastic scattering. applied to atom interferometry as a study case, this simulator solves the atom - light diffraction problem in the elastic case i. e. when the internal state of the atoms remains unchanged. taking this perspective, the light - pulse beam splitting is interpreted as a space - and time - dependent external potential. in a shift from the usual approach based on a system of momentum - space ordinary differential equations, our position - space treatment is flexible and scales favourably for realistic cases where the light fields have an arbitrary complex spatial behaviour rather than being mere plane waves. moreover, the numerical package we developed is effortlessly extended to the problem class of trapped and interacting geometries, which have no simple formulation in the usual framework of momentum - space ordinary differential equations. we check the validity of our model by revisiting several case studies relevant to the precision atom interferometry community. we retrieve analytical solutions when they exist and extend the analysis to more complex parameter ranges in a cross - regime fashion. the flexibility of the approach, the insight it gives, its numerical scalability and accuracy make it an exquisite tool to design, understand and quantitatively analyse metrology - oriented matter - wave interferometry experiments.
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arxiv:2002.05148
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near - future data from esa ' s gaia mission will provide precise, full phase - space information for hundreds of millions of stars out to heliocentric distances of ~ 10 kpc. this " horizon " for full phase - space measurements is imposed by the gaia parallax errors degrading to worse than 10 %, and could be significantly extended by an accurate distance indicator. recent work has demonstrated how spitzer observations of rr lyrae stars can be used to make distance estimates accurate to 2 %, effectively extending the gaia, precise - data horizon by a factor of ten in distance and a factor of 1000 in volume. this letter presents one approach to exploit data of such accuracy to measure the galactic potential using small samples of stars associated with debris from satellite destruction. the method is tested with synthetic observations of 100 stars from the end point of a simulation of satellite destruction : the shape, orientation, and depth of the potential used in the simulation are recovered to within a few percent. the success of this simple test with such a small sample in a single debris stream suggests that constraints from multiple streams could be combined to examine the galaxy ' s dark matter halo in even more detail - - - a truly unique opportunity that is enabled by the combination of spitzer and gaia with our intimate perspective on the galaxy.
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arxiv:1308.2670
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antimatter nuclei in cosmic rays ( cr ) represent a promising discovery channel for the indirect search of dark matter. we present astrophysical background calculations of cr antideuteron ( $ \ overline { d } $ ) and antihelium ( $ \ overline { he } $ ). these particles are produced by high - energy collisions of cr protons and nuclei with the gas nuclei of the interstellar medium. in our calculations, we also consider production and shock acceleration of antinuclei in the shells of supernova remnants ( snrs ). the total flux of $ \ overline { d } $ and $ \ overline { he } $ particles is constrained using new ams measurements on the boron / carbon ( b / c ) and antiproton / proton ( $ \ bar { p } / p $ ) ratios. the two ratios leads to different antiparticle fluxes in the high - energy regime $ e \ gtrsim $ 10 gev / n where, in particular, $ \ bar { p } / p $ - driven calculations leads to a significantly larger antiparticle flux in comparison to predictions from conventional b / c - driven constraints. on the other hand, both approaches provide consistent results in the sub - gev / n energy window, which is where dark matter induced signal may exceed the astrophysical background. in this region, the total antinuclei flux, from interaction in the insterstellar gas and inside snrs, is tightly bounded by the data. shock - acceleration of antiparticles in snrs has a minor influence in the astrophysical background for dark matter searches.
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arxiv:1712.03177
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in a multilingual country like india where 12 different official scripts are in use, automatic identification of handwritten script facilitates many important applications such as automatic transcription of multilingual documents, searching for documents on the web / digital archives containing a particular script and for the selection of script specific optical character recognition ( ocr ) system in a multilingual environment. in this paper, we propose a robust method towards identifying scripts from the handwritten documents at text line - level. the recognition is based upon features extracted using chain code histogram ( cch ) and discrete fourier transform ( dft ). the proposed method is experimented on 800 handwritten text lines written in seven indic scripts namely, gujarati, kannada, malayalam, oriya, tamil, telugu, urdu along with roman script and yielded an average identification rate of 95. 14 % using support vector machine ( svm ) classifier.
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arxiv:2009.07433
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this paper investigates the synthesis of quantum networks built to realize ternary switching circuits in the absence of ancilla bits. the results we established are twofold. the first shows that ternary swap, ternary not and ternary toffoli gates are universal for the realization of arbitrary $ n \ times n $ ternary quantum switching networks without ancilla bits. the second result proves that all $ n \ times n $ quantum ternary networks can be generated by not, controlled - not, multiply - two, and toffoli gates. our approach is constructive. key words : ternary quantum logic synthesis, quantum circuit optimization, group theory.
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arxiv:quant-ph/0509192
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the design for an inductive superconducting quantum interference proximity transistor with enhanced performance, the l - squipt, is presented and analyzed. the interferometer is based on a double - loop structure, where each ring comprises a superconductor - normal metal - superconductor mesoscopic josephson weak - link and the read - out electrode is implemented in the form of a superconducting tunnel probe. our design allows both to improve the coupling of the transistor to the external magnetic field and to increase the characteristic magnetic flux transfer functions, thereby leading to an improved ultrasensitive quantum limited magnetometer. the l - squipt behavior is analyzed in both the dissipative and the dissipationless josephson - like operation modes, in the dissipative or in the dissipationless josephson - like operation mode in the latter case by exploiting both an inductive and a dispersive readout scheme. the improved performance makes the l - squipt promising for magnetic field detection as well as for specific applications in quantum technology, where a responsive dispersive magnetometry at millikelvin temperatures is required.
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arxiv:2203.03948
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this volume contains a selection of the papers presented at termgraph 2018, the tenth edition of the international workshop on computing with terms and graphs. graphs, and graph transformation systems, are used in many areas within computer science : to represent data structures and algorithms, to define computation models, as a general modelling tool to study complex systems, etc. research in this area addresses a range of theoretical and practical issues, including the modelling of first - and higher - order term rewriting by ( acyclic or cyclic ) graph rewriting, graphical frameworks such as interaction nets and sharing graphs ( optimal reduction ), rewrite calculi for the analysis of functional programs, graph reduction implementations of programming languages, graphical calculi modelling concurrent and mobile computations, object - oriented systems, graphs as a model of biological or chemical systems, and automated reasoning and symbolic computation systems working on shared structures. previous editions of termgraph took place in barcelona ( 2002 ), rome ( 2004 ), vienna ( 2006 ), braga ( 2007 ), york ( 2009 ), saarbrucken ( 2011 ), rome ( 2013 ), vienna ( 2014 ) and eindhoven ( 2016 ). termgraph 2018 is affiliated with fscd, which is part of floc.
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arxiv:1902.01510
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the fixed - template constraint satisfaction problem ( csp ) can be seen as the problem of deciding whether a given primitive positive first - order sentence is true in a fixed structure ( also called model ). we study a class of problems that generalizes the csp simultaneously in two directions : we fix a set $ \ mathcal { l } $ of quantifiers and boolean connectives, and we specify two versions of each constraint, one strong and one weak. given a sentence which only uses symbols from $ \ mathcal { l } $, the task is to distinguish whether the sentence is true in the strong sense, or it is false even in the weak sense. we classify the computational complexity of these problems for the existential positive equality - free fragment of first - order logic, i. e., $ \ mathcal { l } = \ { \ exists, \ land, \ lor \ } $, and we prove some upper and lower bounds for the positive equality - free fragment, $ \ mathcal { l } = \ { \ exists, \ forall, \ land, \ lor \ } $. the partial results are sufficient, e. g., for all extensions of the latter fragment.
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arxiv:2205.04787
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##taka ) and divination ( samhita ). this tripartite division is seen in varahamihira ' s 6th century compilation β pancasiddhantika ( literally panca, " five, " siddhanta, " conclusion of deliberation ", dated 575 ce ) β of five earlier works, surya siddhanta, romaka siddhanta, paulisa siddhanta, vasishtha siddhanta and paitamaha siddhanta, which were adaptations of still earlier works of mesopotamian, greek, egyptian, roman and indian astronomy. as explained earlier, the main texts were composed in sanskrit verse, and were followed by prose commentaries. = = = fourth to sixth centuries = = = surya siddhanta though its authorship is unknown, the surya siddhanta ( c. 400 ) contains the roots of modern trigonometry. because it contains many words of foreign origin, some authors consider that it was written under the influence of mesopotamia and greece. this ancient text uses the following as trigonometric functions for the first time : sine ( jya ). cosine ( kojya ). inverse sine ( otkram jya ). later indian mathematicians such as aryabhata made references to this text, while later arabic and latin translations were very influential in europe and the middle east. chhedi calendar this chhedi calendar ( 594 ) contains an early use of the modern place - value hindu β arabic numeral system now used universally. aryabhata i aryabhata ( 476 β 550 ) wrote the aryabhatiya. he described the important fundamental principles of mathematics in 332 shlokas. the treatise contained : quadratic equations trigonometry the value of Ο, correct to 4 decimal places. aryabhata also wrote the arya siddhanta, which is now lost. aryabhata ' s contributions include : trigonometry : ( see also : aryabhata ' s sine table ) introduced the trigonometric functions. defined the sine ( jya ) as the modern relationship between half an angle and half a chord. defined the cosine ( kojya ). defined the versine ( utkrama - jya ). defined the inverse sine ( otkram jya ). gave methods of calculating their approximate numerical values. contains the earliest tables of sine, cosine and versine values, in 3. 75Β° intervals from 0
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https://en.wikipedia.org/wiki/Indian_mathematics
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is there a constant $ r _ 0 $ such that, in any invariant tree network linking rate - $ 1 $ poisson points in the plane, the mean within - network distance between points at euclidean distance $ r $ is infinite for $ r > r _ 0 $? we prove a slightly weaker result. this is a continuum analog of a result of benjamini et al ( 2001 ) on invariant spanning trees of the integer lattice.
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arxiv:2103.00669
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we present a theory which describes a recently introduced model of an evolving, adaptive system in which agents compete to be in the minority. the agents themselves are able to evolve their strategies over time in an attempt to improve their performance. the present theory explicitly demonstrates the self - interaction, or so - called market impact, that agents in such systems experience.
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arxiv:cond-mat/0003379
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we introduce a proximal version of dual coordinate ascent method. we demonstrate how the derived algorithmic framework can be used for numerous regularized loss minimization problems, including $ \ ell _ 1 $ regularization and structured output svm. the convergence rates we obtain match, and sometimes improve, state - of - the - art results.
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arxiv:1211.2717
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in the article correct method for the kinetic boltzmann equation asymptotic solution is formulated, the hilbert ' s and enskog ' s methods are discussed. the equations system of multicomponent non - equilibrium gas dynamics is derived, that corresponds to the first order in the approximate ( asymptotic ) method for solution of the system of kinetic boltzmann equations. it is shown, that the velocity distribution functions of particles, obtained by the proposed method and by enskog ' s method, within enskog ' s approach, are equivalent up to the infinitesimal first order terms of the asymptotic expansion, but, generally speaking, differ in the next order. interpretation of turbulent gas flow is proposed, as stratified on components gas flow, which is described by the derived equations system of multicomponent non - equilibrium gas dynamics.
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arxiv:1303.6275
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many quantum mechanical experiments can be viewed as multi - round interactive protocols between known quantum circuits and an unknown quantum process. fully quantum " coherent " access to the unknown process is known to provide an advantage in many discrimination tasks compared to when only incoherent access is permitted, but it is unclear if this advantage persists when the process is noisy. here, we show that a quantum advantage can be maintained when distinguishing between two noisy single qubit rotation channels. numerical and analytical calculations reveal a distinct transition between optimal performance by fully coherent and fully incoherent protocols as a function of noise strength. moreover, the size of the region of coherent quantum advantage shrinks inverse polynomially in the number of channel uses, and in an intermediate regime an improved strategy is a hybrid of fully - coherent and fully - incoherent subroutines. the fully coherent protocol is based on quantum signal processing, suggesting a generalizable algorithmic framework for the study of quantum advantage in the presence of realistic noise.
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arxiv:2105.08707
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there appears to be a longtime, very slowly evolving state in dense simple fluids which, for high enough density, approaches a glassy nonergodic state. the nature of the nonergodic state can be characterized by the associated static equilibrium state. in particular, systems driven by smoluchowski or newtonian dynamics share the same static equilibrium and nonergodic states. that these systems share the same nonergodic states is a highly nontrivial statement and requires establishing a number of results. in the high - density regime one finds that an equilibrating system decays via a three - step process identified in mode - coupling theory ( mct ). for densities greater than a critical density one has time - power - law decay with exponents a and b. there are sets of linear fluctuation dissipation relations ( fdrs ) which connect the cumulants of these two fields. the form of the fdrs is the same for both smoluchowski or newtonian dynamics. while we show this universality of nonergodic states within perturbation theory, we expect it to be true more generally. the nature of the approach to the nonergodic state has been suggested by mct. it has been a point of contention that mct is a phenomenological theory and not a systematic theory with prospects for improvement. recently a systematic theory has been developed. it naturally allows one to calculate self - consistently density cumulants in a perturbation expansion in a pseudo - potential. at leading order one obtains a kinetic kernel quadratic in the density. this is a " one - loop " theory like mct. at this one - loop level one finds vertex corrections which depend on the three - point equilibrium cumulants. here we assume these vertex - corrections can be ignored and focus on the higher - order loops. we show that one can sum up all of the loop contributions. the higher - order loops do not change the nonergodic state parameters substantially.
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arxiv:1304.6631
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we present an application of the faraday effect to produce a narrow band atomic filter in an alkali metal vapor. in our experiment two raman beams separated in frequency by the ground state hyperfine splitting in 87rb are produced using an eom and then filtered using the faraday effect in an isotopically pure 85rb thermal vapor. an experimental transmission spectra for the filter is presented along with a theoretical calculation. the performance of the filter is then demonstrated and characterized using a fabry - perot etalon. for a temperature of 70 degrees and a longitudinal magnetic field of 80 g a suppression to - 18 db is achieved, limited by the quality of the polarizers.
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arxiv:0904.4142
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the affine weyl group acts on the cohomology ( with compact support ) of affine springer fibers ( local springer theory ) and of parabolic hitchin fibers ( global springer theory ). in this paper, we show that in both situations, the action of the center of the group algebra of the affine weyl group ( the spherical part ) factors through the action of the component group of the relevant centralizers. in the situation of affine springer fibers, this partially verifies a conjecture of goresky - kottwitz - macpherson and bezrukavnikov - varshavsky. we first prove this result for the global springer action, and then deduce the result for the local springer action from that of the global one. the argument strongly relies on the fact that we can deform points on a curve, hence giving an example of using global springer theory to solve more classical problems.
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arxiv:1106.2259
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the discovery of deep spectral features in the x - ray spectrum of 1e1207. 4 - 5209 has pushed this isolated neutron star ( ins ) out of the chorus line, since no other ins has shown significant features in its x - ray continuum. on august 2002, xmm - newton devoted a two - orbit too observation to this target with the aim to better understand the nature of such spectral features, using much improved statistics. indeed, the 260 ksec observation yielded 360, 000 photons from 1e1207. 4 - 5209, allowing for a very sensitive study of the temporal and spectral behaviour of this object.
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arxiv:astro-ph/0310177
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we consider the operator $ - \ delta + b \ cdot \ nabla $ with $ b : \ mathbb r ^ d \ rightarrow \ mathbb r ^ d $ ( $ d \ geq 3 $ ) in the class of form - bounded vector fields ( containing vector fields having critical - order singularities ), and characterize quantitative dependence of the $ \ mathcal w ^ { 1 + \ frac { 2 } { q }, p } $ ( $ 2 \ leq p < q $ ) and the $ c ^ { 0, \ gamma } $ regularity of solutions to the corresponding elliptic equation in $ l ^ p $ on the value of the form - bound of $ b $.
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arxiv:1807.07597
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the middle binomial coefficients can be interpreted as numbers of motzkin paths which have no horizontal steps at positive heights. assigning suitable weights gives some nice polynomial extensions. we determine the hankel determinants and their generating functions for the middle binomial coefficients and derive many conjectures for their polynomial extensions. finally, we explore experimentally some modifications of the middle binomial coefficients whose hankel determinants show an interesting modular pattern and obtain some q - analogs.
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arxiv:2111.14492
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the study of spherical - deformed ground - - state phase transitions in finite nuclei as a function of n and z is hindered by the discrete values of the nucleon number. a resolution of the integer nucleon number problem, and evidence relating to phase transitions in finite nuclei, are discussed from the experimental point of view and interpreted within the framework of the interacting boson model.
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arxiv:nucl-ex/9905002
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recent work suggests that representations learned by adversarially robust networks are more human perceptually - aligned than non - robust networks via image manipulations. despite appearing closer to human visual perception, it is unclear if the constraints in robust dnn representations match biological constraints found in human vision. human vision seems to rely on texture - based / summary statistic representations in the periphery, which have been shown to explain phenomena such as crowding and performance on visual search tasks. to understand how adversarially robust optimizations / representations compare to human vision, we performed a psychophysics experiment using a set of metameric discrimination tasks where we evaluated how well human observers could distinguish between images synthesized to match adversarially robust representations compared to non - robust representations and a texture synthesis model of peripheral vision ( texforms ). we found that the discriminability of robust representation and texture model images decreased to near chance performance as stimuli were presented farther in the periphery. moreover, performance on robust and texture - model images showed similar trends within participants, while performance on non - robust representations changed minimally across the visual field. these results together suggest that ( 1 ) adversarially robust representations capture peripheral computation better than non - robust representations and ( 2 ) robust representations capture peripheral computation similar to current state - of - the - art texture peripheral vision models. more broadly, our findings support the idea that localized texture summary statistic representations may drive human invariance to adversarial perturbations and that the incorporation of such representations in dnns could give rise to useful properties like adversarial robustness.
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arxiv:2202.00838
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the study of spectral properties of natural geometric elliptic partial differential operators acting on smooth sections of vector bundles over riemannian manifolds is a central theme in global analysis, differential geometry and mathematical physics. instead of studying the spectrum of a differential operator $ l $ directly one usually studies its spectral functions, that is, spectral traces of some functions of the operator, such as the spectral zeta function $ \ zeta ( s ) = \ tr l ^ { - s } $ and the heat trace $ \ theta ( t ) = \ tr \ exp ( - tl ) $. the kernel $ u ( t ; x, x ' ) $ of the heat semigroup $ \ exp ( - tl ) $, called the heat kernel, plays a major role in quantum field theory and quantum gravity, index theorems, non - commutative geometry, integrable systems and financial mathematics. we review some recent progress in the study of spectral asymptotics. we study more general spectral functions, such as $ \ tr f ( tl ) $, that we call quantum heat traces. also, we define new invariants of differential operators that depend not only on the their eigenvalues but also on the eigenfunctions, and, therefore, contain much more information about the geometry of the manifold. furthermore, we study some new invariants, such as $ \ tr \ exp ( - tl _ + ) \ exp ( - sl _ - ) $, that contain relative spectral information of two differential operators. finally we show how the convolution of the semigroups of two different operators can be computed by using purely algebraic methods.
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arxiv:2301.08728
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it has been established on many occasions that the set of quotients of prime numbers is dense in the set of positive real numbers. more recently, it has been proved that the set of quotients of primes in the gaussian integers is dense in the complex plane. in this article, we not only extend this result to any imaginary quadratic number ring, but also prove that the set of quotients of primes in any real quadratic number ring is dense in the set of real numbers. to conclude, we show how to extend these results to an arbitrary algebraic number ring.
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arxiv:1607.08319
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current transfer learning methods are mainly based on finetuning a pretrained model with target - domain data. motivated by the techniques from adversarial machine learning ( ml ) that are capable of manipulating the model prediction via data perturbations, in this paper we propose a novel approach, black - box adversarial reprogramming ( bar ), that repurposes a well - trained black - box ml model ( e. g., a prediction api or a proprietary software ) for solving different ml tasks, especially in the scenario with scarce data and constrained resources. the rationale lies in exploiting high - performance but unknown ml models to gain learning capability for transfer learning. using zeroth order optimization and multi - label mapping techniques, bar can reprogram a black - box ml model solely based on its input - output responses without knowing the model architecture or changing any parameter. more importantly, in the limited medical data setting, on autism spectrum disorder classification, diabetic retinopathy detection, and melanoma detection tasks, bar outperforms state - of - the - art methods and yields comparable performance to the vanilla adversarial reprogramming method requiring complete knowledge of the target ml model. bar also outperforms baseline transfer learning approaches by a significant margin, demonstrating cost - effective means and new insights for transfer learning.
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arxiv:2007.08714
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the control of the soviet armed forces and of the soviet economy on the basis of a network of computing centers. kitov ' s proposal was rejected, as later was the 1962 ogas economy management network project. in 1960, the commercial airline reservation system semi - automatic business research environment ( sabre ) went online with two connected mainframes. in 1963, j. c. r. licklider sent a memorandum to office colleagues discussing the concept of the " intergalactic computer network ", a computer network intended to allow general communications among computer users. in 1965, western electric introduced the first widely used telephone switch that implemented computer control in the switching fabric. throughout the 1960s, paul baran and donald davies independently invented the concept of packet switching for data communication between computers over a network. baran ' s work addressed adaptive routing of message blocks across a distributed network, but did not include routers with software switches, nor the idea that users, rather than the network itself, would provide the reliability. davies ' hierarchical network design included high - speed routers, communication protocols and the essence of the end - to - end principle. the npl network, a local area network at the national physical laboratory ( united kingdom ), pioneered the implementation of the concept in 1968 - 69 using 768 kbit / s links. both baran ' s and davies ' inventions were seminal contributions that influenced the development of computer networks. in 1969, the first four nodes of the arpanet were connected using 50 kbit / s circuits between the university of california at los angeles, the stanford research institute, the university of california at santa barbara, and the university of utah. designed principally by bob kahn, the network ' s routing, flow control, software design and network control were developed by the imp team working for bolt beranek & newman. in the early 1970s, leonard kleinrock carried out mathematical work to model the performance of packet - switched networks, which underpinned the development of the arpanet. his theoretical work on hierarchical routing in the late 1970s with student farouk kamoun remains critical to the operation of the internet today. in 1972, commercial services were first deployed on experimental public data networks in europe. in 1973, the french cyclades network, directed by louis pouzin was the first to make the hosts responsible for the reliable delivery of data, rather than this being a centralized service of the network itself. in 1973, peter kirstein put internetworking into practice at university college london ( ucl ), connecting the ar
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https://en.wikipedia.org/wiki/Computer_network
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a general approach for bayesian filtering of multi - object systems is studied, with particular emphasis on the model where each object generates observations independently of other objects. the approach is based on variational calculus applied to generating functionals, using the general version of faa di bruno ' s formula for gateaux differentials. this result enables us to determine some general formulae for the updated generating functional after the application of a multi - object analogue of bayes ' rule.
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arxiv:1202.0949
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in this paper we investigate the connections between ramsey properties of fraisse classes k and the universal minimal flow m ( g _ k ) of the automorphism group g _ k of their fraisse limits. as an extension of a result of kechris, pestov and todorcevic we show that if the class k has finite ramsey degree for embeddings, then this degree equals the size of m ( g _ k ). we give a partial answer to a question of angel, kechris and lyons showing that if k is a relational ramsey class and g _ k is amenable, then m ( g _ k ) admits a unique invariant borel probability measure that is concentrated on a unique generic orbit.
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arxiv:1401.7766
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the mechanism to produce the numerous galactic - centre filaments ( gcf ) that vertically penetrate the galactic plane without clear evidence of connection to the disc remains a mystery. here we show that the gcfs are explained by relics of supernova remnants ( rsnr ) driven by hundreds of supernovae ( sne ) exploded in the star - forming ring of the central molecular zone ( cmz ) at an sn rate of $ \ sim 2 \ times 10 ^ { - 4 } $ y $ ^ { - 1 } $ in the past $ \ sim 0. 5 $ my. the evolution of rsnrs is simulated by the propagation of fast - mode magneto - hydrodynamic ( mhd ) waves, which are shown to converge around the galactic rotation axis by the focusing effect. tangential projection of the cylindrical wave fronts on the sky constitutes the vertical filaments. the snr model explains not only the morphology, but also the non - thermal radio spectrum, smoothed brightness over the distribution area consistent with the $ \ sigma - d $ relation of snr, and the heating mechanism of hot plasma in the gc. we also discuss the implication of the model on the study of the interstellar physics and star - formation activity in the galactic centre.
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arxiv:2210.17219
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metasurfaces have been extensively engineered to produce a wide range of optical phenomena, allowing unprecedented control over the propagation of light. however, they are generally designed as single - purpose devices without a modifiable post - fabrication optical response, which can be a limitation to real - world applications. in this work, we report a nanostructured planar fused silica metalens permeated with a nematic liquid crystal ( nlc ) and gold nanoparticle solution. the physical properties of embedded nlcs can be manipulated with the application of external stimuli, enabling reconfigurable optical metasurfaces. we report all - optical, dynamic control of the metalens optical response resulting from thermo - plasmonic induced changes of the nlc solution associated with the nematic - isotropic phase transition. a continuous and reversible tuning of the metalens focal length is experimentally demonstrated, with a variation of 80 um ( 0. 16 % of the 5 cm nominal focal length ) along the optical axis. this is achieved without direct mechanical or electrical manipulation of the device. the reconfigurable properties are compared with corroborating numerical simulations of the focal length shift and exhibit close correspondence.
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arxiv:2206.02235
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