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time reversal invariance ( tri ) of particles systems has many consequences, among ~ which the celebrated onsager reciprocal relations, a milestone in statistical mechanics dating back to 1931. because for a long time it was believed that ( tri ) dos not hold in presence of a magnetic field, a modification of such relations was proposed by casimir in 1945. only in the last decade, the ~ strict traditional notion of reversibility that led to casimir ' s work has been questioned. it was then found that other symmetries can be used, which allow the onsager reciprocal relations to hold without modification. in this paper we advance this investigation for classical hamiltonian systems, substantially increasing the number of symmetries that yield tri in presence of a magnetic field. we ~ first deduce the most general form of a generalized time reversal operation on the phase space of such a system ; secondly, we express sufficient conditions on the magnetic field which ensure tri. finally, we examine common examples from statistical mechanics and molecular dynamics. our main result is that tri holds in a much wider generality than previously believed, partially explaining why no experimental violation of onsager relations has so far been reported. | arxiv:2008.05193 |
the main result can be given a short and elementary proof which has been incorporated into lemma 3. 2 of arxiv : 1206. 5775 | arxiv:1206.1970 |
the ( in, fe ) sb layers with the fe content up to 13 at. % have been grown on ( 001 ) gaas substrates using the pulsed laser deposition. the tem investigations show that the ( in, fe ) sb layers are epitaxial and free of the inclusions of a second phase. the observation of the hysteretic magnetoresistance curves at temperatures up to 300 k reveals that the curie point is above room temperature. the resonant character of magnetic circular dichroism confirms the intrinsic ferromagnetism in the ( in, fe ) sb layers. we suggest that the ferromagnetism of the ( in, fe ) sb matrix is not carrier - mediated and apparently is determined by the mechanism of superexchange interaction between fe atoms ( this work was presented at the xxi symposium nanophysics and nanoelectronics, nizhny novgorod, march, 13 - 16, 2017 ( book of proceedings v. 1, p. 195 ), http : / / nanosymp. ru / userfiles / symp / 2017 _ v1. pdf ). | arxiv:1705.09318 |
the presence of moonlight is usually a limiting factor for imaging atmospheric cherenkov telescopes due to the high sensitivity of the camera photomultiplier tubes ( pmts ). in their standard configuration, the extra noise limits the sensitivity of the experiment to gamma - ray signals and the higher pmt currents also accelerates pmt aging. since fall 2012, observations have been carried out with veritas under bright moonlight ( moon illumination $ > 35 \ % $ ), in two observing modes, by reducing the voltage applied to the pmts and with uv bandpass filters, which allow observations up to $ \ sim80 \ % $ moon illumination resulting in $ 29 \ % $ more observing time over the course of the year. in this presentation, we provide details of these new observing modes and their performance relative to the standard veritas observations. | arxiv:1508.07186 |
over the past decade, finite element method ( fem ) has served as a foundational numerical framework for approximating the terms of time series expansion ( tse ) as solutions to transient partial differential equation ( pde ). however, the application of high - order finite element ( fe ) to certain classes of pdes, such as diffusion equations and the navier - stokes ( ns ) equations, often leads to numerical instabilities. these instabilities limit the number of valid terms in the series, though the efficiency of time series integration even when resummation techniques like the borel - pad \ ' e - laplace ( bpl ) integrators are employed. in this study, we introduce a novel variational formulation for computing the terms of a tse associated with a given pde using higher - order fes. our approach involves the incorporation of artificial diffusion terms on the left - hand side of the equations corresponding to each power in the series, serving as a stabilization technique. we demonstrate that this method can be interpreted as a minimization of an energy functional, wherein the total variations of the unknowns are considered. furthermore, we establish that the coefficients of the artificial diffusion for each term in the series obey a recurrence relation, which can be determined by minimizing the condition number of the associated linear system. we highlight the link between the proposed technique and the discrete maximum principle ( dmp ) of the heat equation. we show, via numerical experiments, how the proposed technique allows having additional valid terms of the series that will be substantial in enlarging the stability domain of the bpl integrators. | arxiv:2407.03339 |
the shift in condensation temperature caused by interactions is studied up to second order in the s - wave scattering length in a bose - einstein condensate trapped in a temperature - dependent three - dimensional generic potential. with no assumptions other than the mean - field approach and semiclassical approximations it is shown that the inclusion of a temperature - dependent trap improves the empirical values of the numerical parameters compared to those obtained in previous reports on the temperature shift. | arxiv:1404.3255 |
we obtain a $ q $ - linear analogue of gegenbauer ' s expansion of the plane wave. it is expanded in terms of the little $ q $ - gegenbauer polynomials and the \ textit { third } jackson $ q $ - bessel function. the result is obtained by using a method based on bilinear biorthogonal expansions. | arxiv:1211.0739 |
be via : = = = radio = = = radio and microwave communication carry information by modulating properties of electromagnetic waves transmitted through space. specifically, the transmitter generates artificial electromagnetic waves by applying time - varying electric currents to its antenna. the waves travel away from the antenna until they eventually reach the antenna of a receiver, which induces an electric current in the receiving antenna. this current can be detected and demodulated to recreate the information sent by the transmitter. = = = wireless optical = = = = = = = free - space optical ( long - range ) = = = = free - space optical communication ( fso ) is an optical communication technology that uses light propagating in free space to transmit wireless data for telecommunications or computer networking. " free space " means the light beams travel through the open air or outer space. this contrasts with other communication technologies that use light beams traveling through transmission lines such as optical fiber or dielectric " light pipes ". the technology is useful where physical connections are impractical due to high costs or other considerations. for example, free space optical links are used in cities between office buildings that are not wired for networking, where the cost of running cable through the building and under the street would be prohibitive. another widely used example is consumer ir devices such as remote controls and irda ( infrared data association ) networking, which is used as an alternative to wifi networking to allow laptops, pdas, printers, and digital cameras to exchange data. = = = sonic = = = sonic, especially ultrasonic short - range communication involves the transmission and reception of sound. = = = electromagnetic induction = = = electromagnetic induction only allows short - range communication and power transmission. it has been used in biomedical situations such as pacemakers, as well as for short - range rfid tags. = = services = = common examples of wireless equipment include : infrared and ultrasonic remote control devices professional lmr ( land mobile radio ) and smr ( specialized mobile radio ) are typically used by business, industrial, and public safety entities. consumer two - way radio including frs family radio service, gmrs ( general mobile radio service ), and citizens band ( " cb " ) radios. the amateur radio service ( ham radio ). consumer and professional marine vhf radios. airband and radio navigation equipment used by aviators and air traffic control cellular telephones and pagers : provide connectivity for portable and mobile applications, both personal and business. global positioning system ( gps ) : allows drivers of cars and trucks, | https://en.wikipedia.org/wiki/Wireless |
we investigate the impact of instantons on scalar glueball properties in a largely model - independent analytical approach based on the instanton - improved operator product expansion ( iope ) of the $ 0 ^ { + + } $ glueball correlator. the instanton contributions turn out to be dominant, to substantially improve the consistency of the correponding qcd sum rules, and to increase the glueball residue about fivefold. | arxiv:hep-ph/0103204 |
this editorial article partially informs the algorithmic trading community about launching of the new journal " algorithmic trading and controls " ( atc ). atc is an online open - access journal that publishes novel works on algorithmic trading and its control methodologies. in this inaugural article, we discuss nine major challenges that contemporary algo trading faces. there is nothing superstitiously magical about the number " nine, " but so is any other one. several of these challenges are at the strategy level, including for example, trading of illiquid securities or optimal portfolio execution. others are more at the level of risk management and controls, such as on how to develop automated controls, testing and simulations. the editorial views could be inevitably personal and biased, but have been explored with the most innocent intention of contributing to this important field in modern financial services and technologies. | arxiv:2101.08813 |
we continue our study of the representations of the reflection equation algebra ( = rea ) on hilbert spaces, focusing again on the rea constructed from the $ r $ - matrix associated to the standard $ q $ - deformation of $ gl ( n, \ mathbb { c } ) $ for $ 0 < q < 1 $. we consider the poisson structure appearing as the classical limit of the $ r $ - matrix, and parametrize the symplectic leaves explicitly in terms of a type of matrix we call a shape matrix. we then introduce a quantized version of the shape matrix for the rea, and show that each irreducible representation of the rea has a unique shape. | arxiv:2407.03613 |
dynamics of the response of type - ii superconductors to a time - varying magnetic field can exhibit a rate - independent or rate - dependent hysteresis. an energy dissipation rate in a superconductor placed in a time - varying magnetic field depends on its wave form and type of hysteresis, which depends on temperature. the same wave form may reduce the energy dissipation rate in the case of true hysteresis, while it may increase the energy dissipation rate in the case of dynamic hysteresis compared with an energy dissipation rate in a pure sinusoidal field. we present experimental data which confirm the energy dissipation rate calculated using the critical state theory for the case of rate - independent hysteresis and limiting behavior in a normal state for the case of rate - dependent hysteresis. | arxiv:1609.06175 |
confidence curves are used in uncertainty validation to assess how large uncertainties ( $ u _ { e } $ ) are associated with large errors ( $ e $ ). an oracle curve is commonly used as reference to estimate the quality of the tested datasets. the oracle is a perfect, deterministic, error predictor, such as $ | e | = \ pm u _ { e } $, which corresponds to a very unlikely error distribution in a probabilistic framework and is unable unable to inform us on the calibration of $ u _ { e } $. i propose here to replace the oracle by a probabilistic reference curve, deriving from the more realistic scenario where errors should be random draws from a distribution with standard deviation $ u _ { e } $. the probabilistic curve and its confidence interval enable a direct test of the quality of a confidence curve. paired with the probabilistic reference, a confidence curve can be used to check the calibration and tightness of prediction uncertainties. | arxiv:2206.15272 |
the recent discovery of coherent elastic neutrino - nucleus scattering ( ce $ \ nu $ ns ) has created new opportunities to detect and study neutrinos. the interaction cross - section in ce $ \ nu $ ns scales quadratically with the number of neutrons, making heavy - nuclei targets such as active lead - based detectors ideal. in this letter, we discuss for the first time the potential of semiconductor lead perovskites for building neutrino detectors. lead perovskites have emerged in the last decade as revolutionary materials for radiation detection due to their heavy and flexible element composition and their unique optoelectronic properties that result in an excellent energy resolution at an economic cost. while dedicated research and development will be necessary, we find great benefits and no inherent obstacles for the development of lead perovskites as ce $ \ nu $ ns detectors. | arxiv:2302.01597 |
has been studied in philosophy ( since ancient times ) and mathematics ( since the mid - 19th century ). more recently, logic has been studied in cognitive science, which draws on computer science, linguistics, philosophy and psychology, among other disciplines. = = = data science = = = = = = information science = = = information science is an academic field which is primarily concerned with analysis, collection, classification, manipulation, storage, retrieval, movement, dissemination, and protection of information. practitioners within and outside the field study the application and the usage of knowledge in organizations in addition to the interaction between people, organizations, and any existing information systems with the aim of creating, replacing, improving, or understanding the information systems. = = = mathematics = = = mathematics, in the broadest sense, is just a synonym of formal science ; but traditionally mathematics means more specifically the coalition of four areas : arithmetic, algebra, geometry, and analysis, which are, to some degree, the study of quantity, structure, space, and change respectively. = = = statistics = = = statistics is the study of the collection, organization, and interpretation of data. it deals with all aspects of this, including the planning of data collection in terms of the design of surveys and experiments. a statistician is someone who is particularly well versed in the ways of thinking necessary for the successful application of statistical analysis. such people have often gained this experience through working in any of a wide number of fields. there is also a discipline called mathematical statistics, which is concerned with the theoretical basis of the subject. the word statistics, when referring to the scientific discipline, is singular, as in " statistics is an art. " this should not be confused with the word statistic, referring to a quantity ( such as mean or median ) calculated from a set of data, whose plural is statistics ( " this statistic seems wrong " or " these statistics are misleading " ). = = = systems theory = = = systems theory is the transdisciplinary study of systems in general, to elucidate principles that can be applied to all types of systems in all fields of research. the term does not yet have a well - established, precise meaning, but systems theory can reasonably be considered a specialization of systems thinking and a generalization of systems science. the term originates from bertalanffy ' s general system theory ( gst ) and is used in later efforts in other fields, such as the action theory of talcott parsons and the sociological autopoiesis of | https://en.wikipedia.org/wiki/Branches_of_science |
in most attempts to compute the hartle - hawking ` ` wave function of the universe ' ' in euclidean quantum gravity, two important approximations are made : the path integral is evaluated in a saddle point approximation, and only the leading ( least action ) extremum is taken into account. in ( 2 + 1 ) - dimensional gravity with a negative cosmological constant, the second assumption is shown to lead to incorrect results : although the leading extremum gives the most important single contribution to the path integral, topologically inequivalent instantons with larger actions occur in great enough numbers to predominate. one can thus say that in 2 + 1 dimensions - - - and possibly in 3 + 1 dimensions as well - - - entropy dominates action in the gravitational path integral. | arxiv:hep-th/9205022 |
monolayer group vi transition metal dichalcogenides have recently emerged as semiconducting alternatives to graphene in which the true two - dimensionality ( 2d ) is expected to illuminate new semiconducting physics. here we investigate excitons and trions ( their singly charged counterparts ) which have thus far been challenging to generate and control in the ultimate 2d limit. utilizing high quality monolayer molybdenum diselenide ( mose2 ), we report the unambiguous observation and electrostatic tunability of charging effects in positively charged ( x + ), neutral ( xo ), and negatively charged ( x - ) excitons in field effect transistors via photoluminescence. the trion charging energy is large ( 30 mev ), enhanced by strong confinement and heavy effective masses, while the linewidth is narrow ( 5 mev ) at temperatures below 55 k. this is greater spectral contrast than in any known quasi - 2d system. we also find the charging energies for x + and x - to be nearly identical implying the same effective mass for electrons and holes. | arxiv:1211.0072 |
this paper presents a technical approach to robot learning of motor skills which combines active intrinsically motivated learning with imitation learning. our architecture, called sgim - d, allows efficient learning of high - dimensional continuous sensorimotor inverse models in robots, and in particular learns distributions of parameterised motor policies that solve a corresponding distribution of parameterised goals / tasks. this is made possible by the technical integration of imitation learning techniques within an algorithm for learning inverse models that relies on active goal babbling. after reviewing social learning and intrinsic motivation approaches to action learning, we describe the general framework of our algorithm, before detailing its architecture. in an experiment where a robot arm has to learn to use a flexible fishing line, we illustrate that sgim - d efficiently combines the advantages of social learning and intrinsic motivation and benefits from human demonstration properties to learn how to produce varied outcomes in the environment, while developing more precise control policies in large spaces. | arxiv:1804.07269 |
quantum $ a _ n $ - toda field theory in two dimensions is investigated based on the method of quantizing canonical free field. toda exponential operator associated with the fundamental weight $ \ lambda ^ 1 $ is constructed. | arxiv:hep-th/0206232 |
we show that for a countable discrete group which is locally of finite asymptotic dimension, the generic continuous action on cantor space has hyperfinite orbit equivalence relation. in particular, this holds for free groups, answering a question of frisch - kechris - shinko - vidny \ ' anszky. | arxiv:2409.03078 |
we study various mechanisms of electron transmission across the corrugations in the graphene sheet. the spin dependence of the electron transmission probability in the rippled graphene is found. the electrons mean free path and transmission probabilities are analysed for different distributions of ripples in the graphene sheet as well. we demonstrate that the periodically repeated rippled graphene structure ( the superlattice ) leads to the suppression of the transmission of the ballistic electrons with one spin orientation in contrast to the other, depending on the direction of the incoming electron flow. | arxiv:1911.07756 |
it was conjectured by white in 1980 that the toric ring associated to a matroid is defined by symmetric exchange relations. this conjecture was extended to discrete polymatroids by herzog and hibi, and they prove that the conjecture holds for polymatroids with the so called strong exchange property. in this paper we generalize their result to polymatroids that are products of polymatroids with the strong exchange property. this also extends a result by conca on transversal polymatroids. | arxiv:2101.03081 |
each elliptic curve can be embedded uniquely in the projective plane, up to projective equivalence. the hessian curve of the embedding is generically a new elliptic curve, whose isomorphism type depends only on that of the initial elliptic curve. one gets like this a rational map from the moduli space of elliptic curves to itself. we call it the hessian dynamical system. we compute it in terms of the $ j $ - invariant of elliptic curves. we deduce that, seen as a map from a projective line to itself, it has 3 critical values, which correspond to the point at infinity of the moduli space and to the two elliptic curves with special symmetries. moreover, it sends the set of critical values into itself, which shows that all its iterates have the same set of critical values. one gets like this a sequence of dessins d ' enfants. we describe an algorithm allowing to construct this sequence. | arxiv:0809.4340 |
inspired by coarea formula in geometric measure theory, an occupation time formula for continuous semimartingales in $ \ mathbb { r } ^ { n } $ is proven. the occupation measure of a semimartingale, for $ n \ geq2 $, is singular with respect to lebesgue measure but it has a bounded density " transversal " to a foliation, under proper assumptions. in the particular case of the foliation given locally by the distance function from a manifold, the transversal density is related to a geometric local time of the semimartingale at the manifolds of the foliation. | arxiv:1312.3232 |
dynamics is considered as a corollary of the space - time geometry. evolution of a particle in the space - time is described as a chain of connected equivalent geometrical objects. space - time geometry is determined uniquely by the world function $ \ sigma $. proper modification of the minkowskian world function for large space - time interval leads to wobbling of the chain, consisted of timelike straight segments. statistical description of the stochastic world chain coincides with the quantum description by means of the schr \ " { o } dinger equation. proper modification of the minkowskian world function for small space - time interval may lead to appearance of a world chain, having a shape of a helix with timelike axis. links of the chain are spacelike straight segments. such a world chain describes a spatial evolution of a particle. in other words, the helical world chain describes the particle rotation with superluminal velocity. the helical world chain associated with the classical dirac particle, whose world line is a helix. length of world chain link cannot be arbitrary. it is determined by the space - time geometry and, in particular, by the elementary length. there exists some discrimination mechanism, which can discriminate some world chains. | arxiv:0801.1913 |
this article accompanies my icm talk in august 2002. three conjectural directions in gromov - witten theory are discussed : gorenstein properties, bps states, and virasoro constraints. each points to basic structures in the subject which are not yet understood. | arxiv:math/0302077 |
, and a greater need exists for coastal solutions due to sea level rise. = = education = = maritime universities are dedicated to teaching and training students in maritime professions. marine engineers generally have a bachelor ' s degree in marine engineering, marine engineering technology, or marine systems engineering. practical training is valued by employers alongside the bachelor ' s degree. = = = professional institutions = = = imarest world maritime university society for underwater technology ieee oceanic engineering society marine engineering and research institute indian maritime university royal institution of naval architects ( rina ) pakistan marine academy society of naval architects and marine engineers ( sname ) is a worldwide society that is focused on the advancement of the maritime industry. sname was founded in 1893. american society of naval engineers ( asne ) simac = = = degrees in ocean engineering = = = a number of institutions - including mit, uc berkeley, the u. s. naval academy, and texas a & m university - offer a four - year bachelor of science degree specifically in ocean engineering. accredited programs consist of basic undergraduate math and science subjects such as calculus, statistics, chemistry, and physics ; fundamental engineering subjects such as statics, dynamics, electrical engineering, and thermodynamics ; and more specialized subjects such as ocean structural analysis, hydromechanics, and coastal management. graduate students in ocean engineering take classes on more advanced, in - depth subjects while conducting research to complete a graduate - level thesis. the massachusetts institute of technology offers master ' s and phd degrees specifically in ocean engineering. additionally, mit co - hosts a joint program with the woods hole oceanographic institution for students studying ocean engineering and other ocean - related topics at the graduate level. = = = journals and conferences = = = journals about ocean engineering include ocean engineering, the ieee journal of oceanic engineering and the journal of waterway, port, coastal, and ocean engineering. conferences in the field of marine engineering include the ieee oceanic engineering society ' s oceans conference and exposition and the european wave and tidal energy conference ( ewtec ). = = marine engineering achievements = = the delta works is a series of 13 projects designed to protect the netherlands against flooding from the north sea. the american society of civil engineers named it one of the " seven wonders of the modern world ". as of april 2021 twenty - two people have descended to challenger deep, the lowest point in the earth ' s ocean located in the mariana trench. recovery of soviet submarine k - 219 by a joint team of u. s. navy and cia engineers aboard glomar explorer. | https://en.wikipedia.org/wiki/Marine_engineering |
in 1966 gallai asked whether all longest paths in a connected graph have nonempty intersection. this is not true in general and various counterexamples have been found. however, the answer to gallai ' s question is positive for several well - known classes of graphs, as for instance connected outerplanar graphs, connected split graphs, and 2 - trees. a graph is series - parallel if it does not contain $ k _ 4 $ as a minor. series - parallel graphs are also known as partial 2 - trees, which are arbitrary subgraphs of 2 - trees. we present a proof that every connected series - parallel graph has a vertex that is common to all of its longest paths. since 2 - trees are maximal series - parallel graphs, and outerplanar graphs are also series - parallel, our result captures these two classes in one proof and strengthens them to a larger class of graphs. we also describe how this vertex can be found in linear time. | arxiv:1310.1376 |
on - road bicycle lanes improve safety for cyclists, and encourage participation in cycling for active transport and recreation. with many local authorities responsible for portions of the infrastructure, official maps and datasets of bicycle lanes may be out - of - date and incomplete. even " crowdsourced " databases may have significant gaps, especially outside popular metropolitan areas. this thesis presents a method to create a map of bicycle lanes in a survey area by taking sample street scene images from each road, and then applying a deep learning model that has been trained to recognise bicycle lane symbols. the list of coordinates where bicycle lane markings are detected is then correlated to geospatial data about the road network to record bicycle lane routes. the method was applied to successfully build a map for a survey area in the outer suburbs of melbourne. it was able to identify bicycle lanes not previously recorded in the official state government dataset, openstreetmap, or the " biking " layer of google maps. | arxiv:2204.12701 |
large language models have a range of beneficial uses : they can assist in prose, poetry, and programming ; analyze dataset biases ; and more. however, their flexibility and generative capabilities also raise misuse concerns. this report discusses openai ' s work related to the release of its gpt - 2 language model. it discusses staged release, which allows time between model releases to conduct risk and benefit analyses as model sizes increased. it also discusses ongoing partnership - based research and provides recommendations for better coordination and responsible publication in ai. | arxiv:1908.09203 |
we have experimentally investigated the mechanism of the exchange bias in the 2d van der waals ( vdw ) ferromagnets by means of the anomalous hall effect ( ahe ) together with the dynamical magnetization property. the temperature dependence of the ac susceptibility with its frequency response indicates a glassy transition of the magnetic property for the te - rich fegete vdw ferromagnet. we also found that the irreversible temperature dependence in the anomalous hall voltage follows the almeida - thouless line. moreover, the freezing temperature of the spin - glass - like phase is found to correlate with the disappearance temperature of the exchange bias. these important signatures suggest that the emergence of magnetic exchange bias in the 2d van der waals ferromagnets is induced by the presence of the spin - glass - like state in fegete. the unprecedented insights gained from these findings shed light on the underlying principles governing exchange bias in vdw ferromagnets, contributing to the advancement of our understanding in this field. | arxiv:2402.18887 |
this study explores the application of artificial intelligence generated content ( aigc ) technology in urban planning and design, with a particular focus on its impact on placemaking and public participation. by utilizing natural language pro - cessing and image generation models such as stable diffusion, aigc enables efficient transformation from textual descriptions to visual representations, advancing the visualization of urban spatial experiences. the research examines the evolving role of designers in participatory planning processes, specifically how aigc facilitates their transition from traditional creators to collaborators and facilitators, and the implications of this shift on the effectiveness of public engagement. through experimental evaluation, the study assesses the de - sign quality of urban pocket gardens generated under varying levels of designer involvement, analyzing the influence of de - signers on the aesthetic quality and contextual relevance of aigc outputs. the findings reveal that designers significantly improve the quality of aigc - generated designs by providing guidance and structural frameworks, highlighting the substantial potential of human - ai collaboration in urban design. this research offers valuable insights into future collaborative approaches between planners and aigc technologies, aiming to integrate technological advancements with professional practice to foster sustainable urban development. | arxiv:2411.17194 |
semilocal and electroweak strings are well - known to be unstable against unwinding by the condensation of the second higgs component in their cores. a large class of current models of dark matter contains dark scalar fields coupled to the higgs sector of the standard model ( higgs portal ) and / or dark u ( 1 ) gauge fields. it is shown, that higgs - portal - type couplings and a gauge kinetic mixing term of the dark u ( 1 ) gauge field have a significant stabilising effect on semilocal strings in the " visible " sector. | arxiv:1612.03151 |
each labeled rooted tree is associated with a hyperplane arrangement, which is free with exponents given by the depths of the vertices of this tree. the intersection lattices of these arrangements are described through posets of forests. these posets are used to define coalgebras, whose dual algebras are shown to have a simple presentation by generators and relations. | arxiv:math/0301372 |
machine learning models are increasingly used in many engineering fields thanks to the widespread digital data, growing computing power, and advanced algorithms. artificial neural networks ( ann ) is the most popular machine learning model in recent years. although many ann models have been used in the design and analysis of composite materials and structures, there are still some unsolved issues that hinder the acceptance of ann models in the practical design and analysis of composite materials and structures. moreover, the emerging machine learning techniques are posting new opportunities and challenges in the data - based design paradigm. this paper aims to give a state - of - the - art literature review of ann models in the nonlinear constitutive modeling, multiscale surrogate modeling, and design optimization of composite materials and structures. this review has been designed to focus on the discussion of the general frameworks and benefits of ann models to the above problems. moreover, challenges and opportunities in each key problem are identified and discussed. this paper is expected to open the discussion of future research scope and new directions to enable efficient, robust, and accurate data - driven design and analysis of composite materials and structures. | arxiv:2010.09438 |
nanogenerators based on piezoelectric materials convert ever - present mechanical vibrations into electrical power for energetically autonomous wireless and electronic devices. nanowires of piezoelectric polymers are particularly attractive for harvesting mechanical energy in this way, as they are flexible, lightweight and sensitive to small vibrations. previous studies have focused exclusively on nanowires grown by electrospinning, but this involves complex equipment, and high voltages of $ \ approx $ 10 kv that electrically pole the nanowires and thus render them piezoelectric. here we demonstrate that nanowires of poly ( vinylidene fluoride - trifluoroethylene ) ( p ( vdf - trfe ) ) grown using a simple and cost - effective template - wetting technique, can be successfully exploited in nanogenerators without poling. a typical nanogenerator comprising $ \ approx $ 10 $ ^ { 10 } $ highly crystalline, self - poled, aligned nanowires spanning $ \ approx $ 2 cm $ ^ 2 $ is shown to produce a peak output voltage of 3 v at 5. 5 na in response to low - level vibrations. the mechanical - to - electrical conversion efficiency of 11 % exhibited by our template - grown nanowires is comparable with the best previously reported values. our work therefore offers a scalable means of achieving high - performance nanogenerators for the next generation of self - powered electronics. | arxiv:1505.03694 |
we discuss the meromorphic continuation of certain hypergeometric integrals modeled on the selberg integral, including the 3 - point and 4 - point functions of bpz ' s minimal models of 2d cft as described by felder and silvotti and dotsenko and fateev ( the ` ` coulomb gas formalism ' ' ). this is accomplished via a geometric analysis of the singularities of the integrands. in the case that the integrand is symmetric ( as in the selberg integral itself ) or, more generally, what we call ` ` df - symmetric, ' ' we show that a number of apparent singularities are removable, as required for the construction of the minimal models via these methods. | arxiv:2301.03750 |
we have linked the structural and dynamic properties in aqueous solution of amphiphilic charged diblock copolymers poly ( butyl acrylate ) - b - poly ( acrylic acid ), pba - b - paa, synthesized by controlled radical polymerization, with the physico - chemical characteristics of the samples. despite product imperfections, the samples self - assemble in melt and aqueous solutions as predicted by monodisperse microphase separation theory. however, the pba core are abnormally large ; the swelling of pba cores is not due to aa ( the flory parameter chipba / paa, determined at 0. 25, means strong segregation ), but to h - pba homopolymers ( content determined by liquid chromatography at the point of exclusion and adsorption transition lc - peat ). beside the dominant population of micelles detected by scattering experiments, capillary electrophoresis ce analysis permitted detection of two other populations, one of h - paa, and the other of free pba - b - paa chains, that have very short pba blocks and never self - assemble. despite the presence of these free unimers, the self - assembly in solution was found out of equilibrium : the aggregation state is history dependant and no unimer exchange between micelles occurs over months ( time - evolution sans ). the high pba / water interfacial tension, measured at 20 mn / m, prohibits unimer exchange between micelles. pba - b - paa solution systems are neither at thermal equilibrium nor completely frozen systems : internal fractionation of individual aggregates can occur. | arxiv:0708.3596 |
despite the recent progress in deep learning, most approaches still go for a silo - like solution, focusing on learning each task in isolation : training a separate neural network for each individual task. many real - world problems, however, call for a multi - modal approach and, therefore, for multi - tasking models. multi - task learning ( mtl ) aims to leverage useful information across tasks to improve the generalization capability of a model. this thesis is concerned with multi - task learning in the context of computer vision. first, we review existing approaches for mtl. next, we propose several methods that tackle important aspects of multi - task learning. the proposed methods are evaluated on various benchmarks. the results show several advances in the state - of - the - art of multi - task learning. finally, we discuss several possibilities for future work. | arxiv:2203.14896 |
the standard theory of ideal gases ignores the interaction of the gas particles with the thermal radiation ( photon gas ) that fills the otherwise vacuum space between them. this is an unphysical feature since every material absorbs and radiates thermal energy. this interaction may be important in gases since the latter, unlike solids and liquids are capable of undergoing conspicuous volume changes. taking it into account makes the behaviour of the ideal gases more realistic and removes gibbs ' paradox. | arxiv:0901.1799 |
we investigate an operator renormalization group method to extract and describe the relevant degrees of freedom in the evolution of partial differential equations. the proposed renormalization group approach is formulated as an analytical method providing the fundamental concepts of a numerical algorithm applicable to various dynamical systems. we examine dynamical scaling characteristics in the short - time and the long - time evolution regime providing only a reduced number of degrees of freedom to the evolution process. | arxiv:cond-mat/0106156 |
the hera data at large $ q ^ 2 $ and small - $ x $ investigate large distances on the light - cone. at such large distances the scattered quarks can maintain their colour identity by polarizing the vacuum as they transfer energy to it. we calculate the probability for the creation of quark - antiquark pairs from the polarized qcd vacuum and their contribution to the structure function. | arxiv:hep-ph/9606373 |
we explore the mechanics of inflation in simplified extra - dimensional models involving an inflaton interacting with the einstein - maxwell system in two extra dimensions. the models are goldilocks - like in that they are just complicated enough to include a mechanism to stabilize the extra - dimensional size, yet simple enough to solve the full 6d field equations using basic tools. the solutions are not limited to the effective 4d regime with h < < m _ kk ( the latter referring to the mass splitting of the kaluza - klein excitations ) because the full 6d einstein equations are solved. this allows an exploration of inflationary physics in a controlled regime away from the usual 4d lamp - post. the inclusion of modulus stabilization is important as experience with string models teaches that this is usually what makes models fail : stabilization energies dominate the shallow potentials required by slow roll and open up directions to evolve that are steeper than those of the putative inflationary direction. we explore three representative inflationary scenarios within this simple setup. in one the radion is trapped in an inflaton - dependent local minimum whose non - zero energy drives inflation. inflation ends as this energy relaxes to zero when the inflaton finds its minimum. the others involve power - law solutions during inflation. one is an attractor whose features are relatively insensitive to initial conditions but whose slow - roll parameters cannot be arbitrarily small ; the other is not an attractor but can roll much more slowly, until eventually decaying to the attractor. these solutions can satisfy h > m _ kk, but when they do standard 4d fluctuation calculations need not apply. when in a 4d regime the solutions predict eta ~ 0 hence r ~ 0. 11 when n _ s ~ 0. 96 and so are ruled out if tensor modes remain unseen. analysis of general parameters is difficult without a full 6d fluctuation calculation. | arxiv:1605.03297 |
the shortest paths problem is a fundamental challenge in graph theory, with a broad range of potential applications. the algorithms based on matrix multiplication exhibits excellent parallelism and scalability, but is constrained by high memory consumption and algorithmic complexity. traditional shortest paths algorithms are limited by priority queues, such as bfs and dijkstra algorithm, making the improvement of their parallelism a focal issue. we propose a matrix operation - optimized algorithm, which offers improved parallelism, reduced time complexity, and lower memory consumption. the novel algorithm requires $ o ( e _ { wcc } ( i ) ) $ and $ o ( s _ { wcc } \ cdot e _ { wcc } ) $ times for single - source and all - pairs shortest paths problems, respectively, where $ s _ { wcc } $ and $ e _ { wcc } $ denote the number of nodes and edges included in the largest weakly connected component in graph. to evaluate the effectiveness of the novel algorithm, we tested it using graphs from suitesparse matrix collection and gunrock benchmark dataset. our algorithm outperformed the bfs implementations from gunrock and gap ( the previous state - of - the - art solution ), achieving an average speedup of 3. 769 $ \ times $ and 9. 410 $ \ times $, respectively. | arxiv:2208.04514 |
as the number of decentralized applications and users on ethereum grows, the ability of the blockchain to efficiently handle a growing number of transactions becomes increasingly strained. ethereums current execution model relies heavily on sequential processing, meaning that operations are processed one after the other, which creates significant bottlenecks to future scalability demands. while scalability solutions for ethereum exist, they inherit the limitations of the evm, restricting the extent to which they can scale. this paper proposes a novel solution to enable maximally parallelizable executions within ethereum, built out of three self - sufficient approaches. these approaches include strategies in which ethereum transaction state accesses could be strategically and efficiently predetermined, and further propose how the incorporation of gas based incentivization mechanisms could enforce a maximally parallelizable network. | arxiv:2504.01370 |
these lectures present an introduction to supergravity, and are intended for graduate students with a working knowledge of quantum field theory, including the elementary group theory needed for it, but no prior knowledge of general relativity, supersymmetry or string theory is assumed. i will start by introducing the needed elements of general relativity and supersymmetry. i will then describe the simplest cases of supergravity, $ { \ cal n } = 1 $ on - shell in 4 dimensions and $ { \ cal n } = 1 $ off - shell in 3 dimensions. i will introduce superspace formalisms in their simplest cases, and apply them to $ { \ cal n } = 1 $ in 4 dimensions, after which i will show how to couple to matter using superspace. i will introduce the procedure of kk dimensional reduction and describe general supergravity theories, in particular the unique 11 dimensional supergravity. i will then exemplify the issues of kk dimensional reduction on the only complete example of full nonlinear compactification, on the gravitational space $ ads _ 7 \ times s ^ 4 $. finally, i will show how we can use supergravity compactifications together with some string theory information, for realistic embeddings of the standard model, via $ { \ cal n } = 1 $ supergravity in 4 dimensions. | arxiv:1112.3502 |
in nature, instances of synchronisation abound across a diverse range of environments. in the quantum regime, however, synchronisation is typically observed by identifying an appropriate parameter regime in a specific system. in this work we show that this need not be the case, identifying conditions which, when satisfied, guarantee that the individual constituents of a generic open quantum system will undergo completely synchronous limit cycles which are, to first order, robust to symmetry - breaking perturbations. we then describe how these conditions can be satisfied by the interplay between several elements : interactions, local dephasing and the presence of a strong dynamical symmetry - an operator which guarantees long - time non - stationary dynamics. these elements cause the formation of entanglement and off - diagonal long - range order which drive the synchronised response of the system. to illustrate these ideas we present two central examples : a chain of quadratically dephased spin - 1s and the many - body charge - dephased hubbard model. in both cases perfect phase - locking occurs throughout the system, regardless of the specific microscopic parameters or initial states. furthermore, when these systems are perturbed, their non - linear responses elicit long - lived signatures of both phase and frequency - locking. | arxiv:1907.12837 |
recent work has shown that every 3d root system allows the construction of a correponding 4d root system via an ` induction theorem '. in this paper, we look at the icosahedral case of $ h _ 3 \ rightarrow h _ 4 $ in detail and perform the calculations explicitly. clifford algebra is used to perform group theoretic calculations based on the versor theorem and the cartan - dieudonn \ ' e theorem, giving a simple construction of the pin and spin covers. using this connection with $ h _ 3 $ via the induction theorem sheds light on geometric aspects of the $ h _ 4 $ root system ( the $ 600 $ - cell ) as well as other related polytopes and their symmetries, such as the famous grand antiprism and the snub 24 - cell. the uniform construction of root systems from 3d and the uniform procedure of splitting root systems with respect to subrootsystems into separate invariant sets allows further systematic insight into the underlying geometry. all calculations are performed in the even subalgebra of cl ( 3 ), including the construction of the coxeter plane, which is used for visualising the complementary pairs of invariant polytopes, and are shared as supplementary computational work sheets. this approach therefore constitutes a more systematic and general way of performing calculations concerning groups, in particular reflection groups and root systems, in a clifford algebraic framework. | arxiv:2103.07817 |
electric field detection has been widely utilized in many fields such as scientific research and integrated circuits. to enhance the tuning sensitivity of e - field sensor, in this paper, we theoretically proposed a highly sensitive e - field sensor composed of etchless lithium niobate ( ln ) material and hybrid coupling - grating systems in the visible near - infrared regime. such configuration supports high - quality factor quasi - bic resonance, which generates strong localized field confinement. due to the large electro - optic coefficient of ln material, one can shift the wavelength and reflection ratio of resonance by tuning the refractive index of ln material. an analytical theory is carried out to explain the relationship between the refractive index variations and the applied voltages, so we successfully obtained a tuning sensitivity of 40. 8 nm / v and a minimum detectable electric field amplitude of 24. 5 mv with wavelength resolution of 1 nm. due to the low parasitic capacitance of ln material and high conductivity of gold film and ito layer which are utilized as the electrodes, the 3db bandwidth of the devices should exceed 154 ghz. and we believe that such a surface - normal e - field sensor has extensive potential for the extremely weak electric field detection. | arxiv:2212.10026 |
gauge mediated supersymmetry ( susy ) - breaking ( gmsb ) furnishes the best idea to overcome the flavor problem in ssms, supersymmetric stand models ( sm ). however, implemented in the minimal ssm ( mssm ), a very serious fine - tuning problem arises, owing to the absence of a large $ a _ t $ term in the stop sector to radiatively enhance the sm - like higgs boson mass. in the extended gmsb coupling $ h _ u $ to messengers can alleviate this problem but encounters the $ a _ t / m _ { h _ u } ^ 2 $ problem, i. e., at the same time a large $ m _ { h _ u } ^ 2 $ is generated, rendering radiative electroweak spontaneously breaking ( ewsb ) problematic. this issue shows similarity to another long - standing problem of gmsb, the $ \ mu / { b _ \ mu } $ problem, and, of great interest, we find that they may admit the same solution, nonradiative ewsb. such a solution is naturally accommodated when both $ h _ u $ and $ h _ d $ couple to messengers. as a bonus of nonradiative ewsb, the sleptons tend to be very light due to the significant renormalization group equation effect and they are able to account for the $ ( g - 2 ) _ \ mu $ puzzle. as a concrete example, we investigate a hidden sector with $ ( 10, \ overline { 10 } ) $ messengers. | arxiv:1610.06024 |
a set of \ ( k \ ) spanning trees in a graph \ ( g \ ) is called a set of \ textit { completely independent spanning trees ( cists ) } if, for every pair of vertices \ ( x \ ) and \ ( y \ ), the paths connecting \ ( x \ ) and \ ( y \ ) across different trees do not share any vertices or edges, except for \ ( x \ ) and \ ( y \ ) themselves. hasunuma conjectured that every \ ( 2k \ ) - connected graph contains exactly \ ( k \ ) completely independent spanning trees ( cists ). however, p \ ' et \ ' erfalvi disproved this conjecture. when \ ( k = 2 \ ), the two cists are called a \ textit { dual - cist }. it has been shown that determining whether a graph can have \ ( k \ ) cists is an np - complete problem, even when \ ( k = 2 \ ). in $ 2017 $, darties et al. raised the question of whether the $ 6 - $ dimensional hypercube \ ( q _ 6 \ ) can have three completely independent spanning trees ( cists ). this paper provides an answer to that question. in this paper, we first present a necessary condition for \ ( k \ ) - regular, \ ( k \ ) - connected bipartite graphs to have \ ( \ left \ lfloor \ frac { k } { 2 } \ right \ rfloor \ ) cists. we also investigate that the hypercube of dimension \ ( n \ ) cannot have \ ( \ frac { n } { 2 } \ ) cists, which means hasunuma ' s conjecture does not hold for the hypercube \ ( q _ n \ ) when \ ( n \ ) is an even integer \ ( 2 < n \ leq 10 ^ 7 \ ), except when \ ( n = 2 ^ r \ ) and \ ( n \ in \ { 161038, 215326, 2568226, 3020626, 7866046, 9115426 \ } \ ). this result also resolves a question posed by darties et al. the construction of multiple cists on the underlying graph of a network has practical applications in ensuring the fault tolerance of data transmission. in this context, we also provide a construction for three completely independent spanning trees in the hypercube \ ( q _ n \ | arxiv:2410.03379 |
we calculate, in the continuum limit of quenched lattice qcd, the matrix elements of the heavy - heavy vector current between heavy - light pseudoscalar meson states. we present the form factors for different values of the initial and final meson masses at finite momentum transfer. in particular, we calculate the non - perturbative correction to the differential decay rate of the process b - - > d l nu including the case of a non - vanishing lepton mass. | arxiv:0707.0587 |
in this work, we study and determine the dimensions of euclidean and hermitian hulls of two classical propagation rules, namely, the direct sum construction and the $ ( \ mathbf { u }, \ mathbf { u + v } ) $ - construction. some new criteria for the resulting codes derived from these two propagation rules being self - dual, self - orthogonal, or linear complementary dual ( lcd ) codes are given. as an application, we construct some linear codes with prescribed hull dimensions, many new binary, ternary euclidean formally self - dual ( fsd ) lcd codes, and quaternary hermitian fsd lcd codes. some new even - like, odd - like, euclidean and hermitian self - orthogonal codes are also obtained. many of { these } codes are also ( almost ) optimal according to the database maintained by markus grassl. our methods contribute positively to improve the lower bounds on the minimum distance of known lcd codes. | arxiv:2211.04815 |
building our previous work, we explore an analogy to the differential symbol map used in the bloch - gabber - kato theorem. within this framework, for an appropriate variety over a field, the higher chow group corresponds to the 0 - th kato homology group. using methods inspired by akhtar ' s theorem on higher chow groups, we investigate the structure of the 0 - th kato homology group for varieties over arithmetic fields, including finite fields, local fields, and global fields of positive characteristic. we also express our results in terms of reciprocity sheaves. | arxiv:2501.11224 |
in this work we establish a simple yet effective strategy, based on optimal transport theory, for enabling a group of robots to accomplish complex tasks, such as shape formation and assembly. we demonstrate the feasibility of this approach and rigorously prove collision avoidance and convergence properties of the proposed algorithms. | arxiv:1904.02804 |
we present infrared luminosity functions and dust mass functions for the eagle cosmological simulation, based on synthetic multi - wavelength observations generated with the skirt radiative transfer code. in the local universe, we reproduce the observed infrared luminosity and dust mass functions very well. some minor discrepancies are encountered, mainly in the high luminosity regime, where the eagle - skirt luminosity functions mildly but systematically underestimate the observed ones. the agreement between the eagle - skirt infrared luminosity functions and the observed ones gradually worsens with increasing lookback time. fitting modified schechter functions to the eagle - skirt luminosity and dust mass functions at different redshifts up to $ z = 1 $, we find that the evolution is compatible with pure luminosity / mass evolution. the evolution is relatively mild : within this redshift range, we find an evolution of $ l _ { \ star, 250 } \ propto ( 1 + z ) ^ { 1. 68 } $, $ l _ { \ star, \ text { tir } } \ propto ( 1 + z ) ^ { 2. 51 } $ and $ m _ { \ star, \ text { dust } } \ propto ( 1 + z ) ^ { 0. 83 } $ for the characteristic luminosity / mass. for the luminosity / mass density we find $ \ varepsilon _ { 250 } \ propto ( 1 + z ) ^ { 1. 62 } $, $ \ varepsilon _ { \ text { tir } } \ propto ( 1 + z ) ^ { 2. 35 } $ and $ \ rho _ { \ text { dust } } \ propto ( 1 + z ) ^ { 0. 80 } $, respectively. the mild evolution of the dust mass density is in relatively good agreement with observations, but the slow evolution of the infrared luminosity underestimates the observed luminosity evolution significantly. we argue that these differences can be attributed to increasing limitations in the radiative transfer treatment due to increasingly poorer resolution, combined with a slower than observed evolution of the sfr density in the eagle simulation and the lack of agn emission in our eagle - skirt post - processing recipe. | arxiv:2004.02713 |
the hamiltonian approach to the general relativity and the standard model is studied in the context of its consistency with the newton law, the higgs effect, the hubble cosmological evolution and the cosmic microwave background radiation physics. the version of the higgs potential is proposed, where its constant parameter is replaced by the dynamic zeroth fourier harmonic of the very higgs field. in this model, the extremum of the coleman - - weinberg effective potential obtained from the unit vacuum - - vacuum transition amplitude immediately predicts mass of higgs field and removes tremendous vacuum cosmological density. we show that the relativity principles unambiguously treat the planck epoch, in the general relativity, as the present - day one. it was shown that there are initial data of the electro - weak epoch compatible with supposition that all particles in the universe are final products of decays of primordial higgs particles and w -, z - vector bosons created from vacuum at the instant treated as the " big - bang ". | arxiv:0705.0655 |
in this paper, a model that was recently derived in reinken et al. [ 11 ] to describe the dynamics of microswimmer suspensions is studied. in particular, the global existence of weak solutions, their weak - strong uniqueness and a connection to a different model that was proposed in wensink et al. [ 18 ] is shown. | arxiv:2011.13204 |
let $ \ gamma = $ cay $ ( g, t ) $ be a cayley digraph over a finite abelian group $ g $ with respect the generating set $ t \ not \ ni0 $. $ \ gamma $ has order ord $ ( \ gamma ) = | g | = n $ and degree deg $ ( \ gamma ) = | t | = d $. let $ k ( \ gamma ) $ be the diameter of $ \ gamma $ and denote $ \ kappa ( d, n ) = \ min \ { k ( \ gamma ) : ~ \ textrm { ord } ( \ gamma ) = n, \ textrm { deg } ( \ gamma ) = d \ } $. we give a closed expression, $ \ ell ( d, n ) $, of a tight lower bound of $ \ kappa ( d, n ) $ by using the so called { \ em solid density } introduced by fiduccia, forcade and zito. a digraph $ \ gamma $ of degree $ d $ is called { \ em tight } when $ k ( \ gamma ) = \ kappa ( d, | \ gamma | ) = \ ell ( d, | \ gamma | ) $ holds. recently, the { \ em dilating method } has been developed to derive a sequence of digraphs of constant solid density. in this work, we use this method to derive a sequence of tight digraphs $ \ { \ gamma _ i \ } _ { i = 1 } ^ { \ textrm { c } ( \ gamma ) } $ from a given tight digraph $ \ gamma $. moreover, we find a closed expression of the cardinality c $ ( \ gamma ) $ of this sequence. it is perhaps surprising that c $ ( \ gamma ) $ depends only on $ n $ and $ d $ and not on the structure of $ \ gamma $. | arxiv:1806.03899 |
understanding long videos, ranging from tens of minutes to several hours, presents unique challenges in video comprehension. despite the increasing importance of long - form video content, existing benchmarks primarily focus on shorter clips. to address this gap, we introduce infinibench a comprehensive benchmark for very long video understanding which presents 1 ) the longest video duration, averaging 52. 59 minutes per video 2 ) the largest number of question - answer pairs, 108. 2k 3 ) diversity in questions that examine nine different skills and include both multiple - choice questions and open - ended questions 4 ) human - centric, as the video sources come from movies and daily tv shows, with specific human - level question designs such as movie spoiler questions that require critical thinking and comprehensive understanding. using infinibench, we comprehensively evaluate existing large multi - modality models ( lmms ) on each skill, including the commercial models such as gpt - 4o and gemini 1. 5 flash and the open - source models. the evaluation shows significant challenges in our benchmark. our findings reveal that even leading ai models like gpt - 4o and gemini 1. 5 flash face challenges in achieving high performance in long video understanding, with average accuracies of just 49. 16 \ % and 42. 72 \ %, and average scores of 3. 22 and 2. 71 out of 5, respectively. we hope this benchmark will stimulate the lmms community towards long video and human - level understanding. our benchmark can be accessed at https : / / vision - cair. github. io / infinibench / | arxiv:2406.19875 |
sequence organizations are viewed from two points : one is from informational redundancy or informational correlation ( ic ) and another is from k - mer frequency statistics. two problems are investigated. the first is how the ics exceed the fluctuation bound and the order emerges from fluctuation in a genome when the sequence length attains some critical value. we demonstrated that the transition from fluctuation to order takes place at about sequence length 200 - 300 thousands bases for human and e coli genome. it means that the life emerges from a region between macroscopic and microscopic. the second is about the statistical law of the k - mer organization in a genome under the evolutionary pressure and functional selection. we deduced a sum rule q ( k, n ) on the k - mer frequency deviations from the randomness in a n - long sequence of genome and deduced the relations of q ( k, n ) with k and n. we found that q ( k, n ) increases with length n at a constant rate for most genome sequences and demonstrated that when the functional selection of k - mers is accumulated to some critical value the ordering takes place. an important finding is the sum rule correlated with the evolutionary complexity of the genome. | arxiv:1004.3843 |
quantum random walks are the quantum counterpart of classical random walks, and were recently studied in the context of quantum computation. a quantum random walker is subject to self interference, leading to a remarkably different behavior than that of classical random walks such as ballistic propagation or localization due to disorder. physical implementations of quantum walks have only been made in very small scale systems severely limited by decoherence. here we show that the propagation of photons in waveguide lattices, which have been studied extensively in recent years, are essentially an implementation of quantum walks. since waveguide lattices are easily constructed at large scales and display negligible decoherence, they can serve as an ideal and versatile experimental playground for the study of quantum walks and quantum algorithms. we experimentally observe quantum walks in large systems ( ~ 100 sites ) and confirm quantum walks effects which were studied theoretically, including ballistic propagation, disorder and boundary related effects. | arxiv:0707.0741 |
we propose nonlinear parabolic equations of monge - - amp \ ' ere ( m - - a ) type that admit regional, single poin, and global blow - up of similarity type. a similar model is derived for a fourth - order m - - a flow. | arxiv:0906.4233 |
an x - ray imaging technique is used to probe the stability of 3 - dimensional granular packs in a slowly rotating drum. well before the surface reaches the avalanche angle, we observe intermittent plastic events associated with collective rearrangements of the grains located in the vicinity of the free surface. the energy released by these discrete events grows as the system approaches the avalanche threshold. by testing various preparation methods, we show that the pre - avalanche dynamics is not solely controlled by the difference between the free surface inclination and the avalanche angle. as a consequence, the measure of the pre - avalanche dynamics is unlikely to serve as a tool for predicting macroscopic avalanches. | arxiv:cond-mat/0412074 |
a procedure for using the eigenvectors of the elements of the representations of a discrete group in model building is introduced and is used to construct a model that produces a large reactor mixing angle, sin ^ 2 ( theta13 ) = 2 / 3 sin ^ 2 ( pi / 16 ), in agreement with recent neutrino oscillation observations. the model fully constrains the neutrino mass ratios and predicts normal hierarchy with the light neutrino mass, m1 ~ 25 mev. motivated by the model, a new mixing ansatz is postulated which predicts all the mixing angles within 1sigma errors. | arxiv:1211.3364 |
numerical methods of approximate solution of the cauchy problem for coupled systems of evolution equations are considered. separating simpler subproblems for individual components of the solution achieves simplification of the problem at a new level in time. the decoupling method, a significant approach to simplifying the problem, is based on the decomposition of the problem ' s operator matrix. the approximate solution is constructed based on the linear composition of solutions to auxiliary problems. the paper investigates decoupling variants based on extracting the diagonal part of the operator matrix and the lower and upper triangular submatrices. the study introduces a new decomposition approach, which involves splitting the operator matrix into rows and columns. the composition stage utilizes various variants of splitting schemes, showcasing the versatility of the approach. in additive operator - difference schemes, we can distinguish explicit - implicit schemes, factorized schemes for two - component splitting, and regularized schemes for general multicomponent splitting. the study of stability of two - and three - level decoupling composition schemes is carried out using the theory of stability ( correctness ) of operator - difference schemes for finite - dimensional hilbert spaces. the theoretical results of the decoupling technique for systems of evolution equations are illustrated on a test two - dimensional problem for a coupled system of two diffusion equations with inhomogeneous self - and cross - diffusion coefficients. | arxiv:2408.13553 |
spin - polarized first - principles calculations have been performed on zigzag boron - nitride nanoribbons ( z - bnnrs ) with lines of alternating fused pentagon ( p ) and heptagon ( h ) rings ( pentagon - heptagon - line - defect ) at single edge as well as at both edges. the number of line ( n ) of the pentagon - heptagon - defect has been varied from 1 to 8 for 10 - zbnnrs. among the different spin - configurations which we have studied, we find that, the spin - configuration with ferromagnetic ordering at each edge and anti - ferromagnetic ordering across the edges is quite interesting. for this spin - configuration, we find that, if the introduced ph - line - defect is odd numbered, the systems behave as spin - polarized semi - conductors, but, for even numbered, all the systems show interesting anti - ferromagnetic half - metallic behavior. robustness of these results has been cross checked by the variation of the line - defect position and also by the variation of the width [ from ~ 1. 1 nm ( 6 - zbnnr ) to ~ 3. 3 nm ( 16 - zbnnr ) ] of the ribbon. density of states ( dos ), projected - dos and band - structure analysis have been accomplished to understand the reasons for these differences between even and odd - line - defects. the main reason for many of the observed changes was traced back to the change in edge nature of the bnnr, which indeed dictates the properties of the systems. | arxiv:1306.5049 |
we present quantum graphs with remarkably regular spectral characteristics. we call them { \ it regular quantum graphs }. although regular quantum graphs are strongly chaotic in the classical limit, their quantum spectra are explicitly solvable in terms of periodic orbits. we present analytical solutions for the spectrum of regular quantum graphs in the form of explicit and exact periodic orbit expansions for each individual energy level. | arxiv:quant-ph/0108054 |
trajectory prediction of road users in real - world scenarios is challenging because their movement patterns are stochastic and complex. previous pedestrian - oriented works have been successful in modelling the complex interactions among pedestrians, but fail in predicting trajectories when other types of road users are involved ( e. g., cars, cyclists, etc. ), because they ignore user types. although a few recent works construct densely connected graphs with user label information, they suffer from superfluous spatial interactions and temporal dependencies. to address these issues, we propose multiclass - sgcn, a sparse graph convolution network based approach for multi - class trajectory prediction that takes into consideration velocity and agent label information and uses a novel interaction mask to adaptively decide the spatial and temporal connections of agents based on their interaction scores. the proposed approach significantly outperformed state - of - the - art approaches on the stanford drone dataset, providing more realistic and plausible trajectory predictions. | arxiv:2206.15275 |
this paper presents a numerical method to solve a time - fractional burgers equation, achieving order of convergence $ ( 2 - \ alpha ) $ in time, here $ \ alpha $ represents the order of the time derivative. the fractional derivative is modeled by caputo - prabhakar ( cp ) formulation, which incorporates a kernel defined by the three - parameter mittag - leffler function. finite difference methods are employed for the discretization of the derivatives. to handle the non - linear term, the newton iteration method is used. the proposed numerical scheme is proven to be stable and convergent in the $ l _ { \ infty } $ norm. the validity of the theory is supported by two numerical examples. | arxiv:2410.20192 |
we have analyzed { \ it rossi } x - ray timing explorer ( rxte ) pointed observations of the outbursts of black hole and neutron star soft x - ray transients in which an initial low / hard state or ` island ' state, followed by a transition to a softer state, was observed. in three sources, the black hole transient xte j1550 - 564, the neutron star transient aquila x - 1 and a quasi - persistent neutron star low mass x - ray binary ( lmxb ) 4u 1705 - 44, two such outbursts were found. we find that the flux of the soft x - ray peak, which lags the hard x - ray peak by a few days to several weeks, scales with the flux of the hard x - ray peak. we conclude that we are able to predict the soft x - ray outburst peak flux based on the ` preceding ' hard x - ray peak flux, implying an early set up of the outbursts. we also find that the x - ray luminosity corresponding to the peak of the hard x - ray flux, which corresponds to the x - ray luminosity of the start of the hard - to - soft state transition, varies by a factor of about 2. if the accretion geometry early in the outburst rise is composed of two flows ( e. g. a hot sub - keplerian halo flow and a keplerian disk flow, or an outflow and a keplerian disk flow ), the correlation indicates that the two flows are initially related, probably due to processes in the outer part of the accretion disk. we discuss constraints on a single flow model and a disk - jet model from these observations. | arxiv:astro-ph/0407515 |
the problem of continuous quantum phase transitions in metals involves critical bosons coupled to a fermi surface. we solve the theory in the limit of a large number, n _ b, of bosonic flavors, where the bosons transform in the adjoint representation, while the fermions are in the fundamental representation of a global su ( n _ b ) flavor symmetry group. the leading large n _ b solution corresponds to a non - fermi liquid coupled to wilson - fisher bosons. in a certain energy range, the fermion velocity vanishes - resulting in the destruction of the fermi surface. subleading 1 / n _ b corrections correspond to a qualitatively different form of landau damping of the bosonic critical fluctuations. we discuss the model in d = 3 - epsilon but because of the additional control afforded by large n _ b, our results are valid down to d = 2. in the limit epsilon < < 1, the large n _ b solution is consistent with the rg analysis of ref. 1. | arxiv:1312.3321 |
we study distributions of eigenvalue curvatures for a block diagonal random matrix perturbed by a full random matrix. the most natural physical realization of this model is a quantum chaotic system with some inherent symmetry, such that its energy levels form two independent subsequences, subject to a generic perturbation which does not respect the symmetry. we describe analytically a crossover in the form of a curvature distribution with a tunable parameter namely the ratio of inter / intra subsystem coupling strengths. we find that the peak value of the curvature distribution is much more sensitive to the changes in this parameter than the power law tail behaviour. this observation may help to clarify some qualitative features of the curvature distributions observed experimentally in acoustic resonances of quartz blocks. | arxiv:cond-mat/0303355 |
we study nonlinear evolutions of binary black hole mergers, uncovering power - law contributions generated by the long - range behaviour of the highly - curved dynamical spacetime. the result is achieved by exploiting the strong increase of the tail relevance due to binary eccentricity, recently observed in perturbative evolutions of a small - mass - ratio binary under accurate radiation reaction by albanesi and collaborators [ physrevd. 108. 084037 ]. we demonstrate the presence of this enhancement even in the nonlinear case of comparable - mass binary mergers in eccentric orbits, using the public rit waveform catalog. the instantaneous frequency of the simulations displays large oscillations at intermediate to late - times, due to interference terms in the transition between a fast - decaying, constant - frequency quasinormal - mode driven regime, and a power - law, slowly - decaying one. the power - law exponent displays broad convergence with perturbative predictions, although longer and more accurate simulations will be needed to pinpoint the asymptotic value. our results offer yet another confirmation of the highly predictive power of black hole perturbation theory in the presence of a source, even when applied to nonlinear solutions. the magnitude of the tail signal is within reach of gravitational - wave detectors measurements, unlocking the possibility of observationally investigating an additional set of general relativistic predictions on the long - range dynamics of relaxing compact objects. | arxiv:2310.12968 |
computing an auc as a performance measure to compare the quality of different machine learning models is one of the final steps of many research projects. many of these methods are trained on privacy - sensitive data and there are several different approaches like $ \ epsilon $ - differential privacy, federated machine learning and cryptography if the datasets cannot be shared or used jointly at one place for training and / or testing. in this setting, it can also be a problem to compute the global auc, since the labels might also contain privacy - sensitive information. there have been approaches based on $ \ epsilon $ - differential privacy to address this problem, but to the best of our knowledge, no exact privacy preserving solution has been introduced. in this paper, we propose an mpc - based solution, called ppaurora, with private merging of individually sorted lists from multiple sources to compute the exact auc as one could obtain on the pooled original test samples. with ppaurora, the computation of the exact area under precision - recall and receiver operating characteristic curves is possible even when ties between prediction confidence values exist. we use ppaurora to evaluate two different models predicting acute myeloid leukemia therapy response and heart disease, respectively. we also assess its scalability via synthetic data experiments. all these experiments show that we efficiently and privately compute the exact same auc with both evaluation metrics as one can obtain on the pooled test samples in plaintext according to the semi - honest adversary setting. | arxiv:2102.08788 |
the h. e. s. s. experiment is an array of four identical imaging atmospheric cherenkov telescopes in the southern hemisphere, designed to observe very high energy gamma - rays ( e > 100 gev ). these high energy gamma - rays can be used to search for annihilations of dark matter particles in dense environments. dwarf galaxy dynamics shows that they are dark matter - dominated environments. several observation campaigns on dwarf satellite galaxies of the milky way were launched by h. e. s. s.. the observations are reviewed. in the absence of clear signals, constraints on the dark matter particle annihilation cross - section have been derived in different particle physics scenarios. some possible enhancements of the gamma - ray flux are studied, i. e., the sommerfeld effect, the internal bremsstrahlung and the substructures in the dark matter halo. | arxiv:1111.5781 |
we review the recent theoretical developments towards understanding the mott phases and quantum phase transition of extended bose - hubbard models on lattices in two spatial dimensions. we focuss on the description of these systems using the dual vortex picture and point out the crucial role played by the geometry of underlying lattices in determining the nature of both the mott phases and the quantum phase transitions. we also briefly compare the results of dual vortex theory with quantum monte carlo results. | arxiv:cond-mat/0703506 |
we compute observables in the interacting rank - one 6d $ \ mathcal { n } = ( 2, 0 ) $ scft at large r - charge. we focus on correlators involving $ \ phi ^ n $, namely symmetric products of the bottom component of the supermultiplet containing the stress - tensor. by using the moduli space effective action and methods from the large - charge expansion, we compute the ope coefficients $ \ langle \ phi ^ n \ phi ^ m \ phi ^ { n + m } \ rangle $ in an expansion in 1 / n. the coefficients of the expansion are only partially determined from the 6d perspective, but we manage to fix them order - by - order in 1 / n numerically by utilizing the 6d / 2d correspondence. this is made possible by the fact that this $ 6d $ observable can be extracted in 2d from a specific double - scaling limit of the vacuum virasoro block, which can be efficiently computed numerically. we also extend the computation to higher - rank scfts, and discuss various applications of our results to 6d as well as 2d. | arxiv:2409.05944 |
we take an application of the kernel lemma by kostochka and yancey to its logical conclusion. the consequence is a sort of magical way to draw conclusions about list coloring ( and online list coloring ) just from the existence of an independent set incident to many edges. we use this to prove an ore - degree version of brooks ' theorem for online list - coloring. the ore - degree of an edge $ xy $ in a graph $ g $ is $ \ theta ( xy ) = d _ g ( x ) + d _ g ( y ) $. the ore - degree of $ g $ is $ \ theta ( g ) = \ max _ { xy \ in e ( g ) } \ theta ( xy ) $. we show that every graph with $ \ theta \ ge18 $ and $ \ omega \ le \ frac { \ theta } { 2 } $ is online $ \ left \ lfloor \ frac { \ theta } { 2 } \ right \ rfloor $ - choosable. in addition, we prove an upper bound for online list - coloring triangle - free graphs : $ \ chi _ { ol } \ le \ delta + 1 - \ lfloor \ frac { 1 } { 4 } \ lg ( \ delta ) \ rfloor $. finally, we characterize gallai trees as the connected graphs $ g $ with no independent set incident to at least $ | g | $ edges. | arxiv:1512.08130 |
we study directional mean dimension of $ \ mathbb { z } ^ k $ - actions ( where $ k $ is a positive integer ). on the one hand, we show that there is a $ \ mathbb { z } ^ 2 $ - action whose directional mean dimension ( considered as a $ [ 0, + \ infty ] $ - valued function on the torus ) is not continuous. on the other hand, we prove that if a $ \ mathbb { z } ^ k $ - action is continuum - wise expansive, then the values of its $ ( k - 1 ) $ - dimensional directional mean dimension are bounded. this is a generalization ( with a view towards meyerovitch and tsukamoto ' s theorem on mean dimension and expansive multiparameter actions ) of a classical result due to ma \ ~ n \ ' e : any compact metrizable space admitting an expansive homeomorphism ( with respect to a compatible metric ) is finite - dimensional. | arxiv:2108.06308 |
improving the performance of superconducting qubits and resonators generally results from a combination of materials and fabrication process improvements and design modifications that reduce device sensitivity to residual losses. one instance of this approach is to use trenching into the device substrate in combination with superconductors and dielectrics with low intrinsic losses to improve quality factors and coherence times. here we demonstrate titanium nitride coplanar waveguide resonators with mean quality factors exceeding two million and controlled trenching reaching 2. 2 $ \ mu $ m into the silicon substrate. additionally, we measure sets of resonators with a range of sizes and trench depths and compare these results with finite - element simulations to demonstrate quantitative agreement with a model of interface dielectric loss. we then apply this analysis to determine the extent to which trenching can improve resonator performance. | arxiv:1709.10015 |
we report new estimates of the time delays in the quadruple gravitationally lensed quasar pg1115 + 080, obtained from the monitoring data in filter r with the 1. 5 - m telescope at the maidanak mountain ( uzbekistan, central asia ) in 2004 - 2006. the time delays are 16. 4 days between images c and b, and 12 days between c and a1 + a2, with image c being leading for both pairs. the only known estimates of the time delays in pg1115 are those based on observations by schechter et al. ( 1997 ) - - 23. 7 and 9. 4 days between images c and b, c and a1 + a2, respectively, as calculated by schechter et al., and 25 and 13. 3 days as revised by barkana ( 1997 ) for the same image components with the use of another method. the new values of time delays in pg 1115 + 080 may be expected to provide larger estimates of the hubble constant thus decreasing a diversity between the h _ 0 estimates taken from gravitationally lensed quasars and with other methods. | arxiv:0910.1260 |
in this paper we discuss the local discontinuous galerkin methods coupled with two specific explicit - implicit - null time discretizations for solving one - dimensional nonlinear diffusion problems $ u _ t = ( a ( u ) u _ x ) _ x $. the basic idea is to add and subtract two equal terms $ a _ 0 u _ { xx } $ on the right hand side of the partial differential equation, then to treat the term $ a _ 0 u _ { xx } $ implicitly and the other terms $ ( a ( u ) u _ x ) _ x - a _ 0 u _ { xx } $ explicitly. we give stability analysis for the method on a simplified model by the aid of energy analysis, which gives a guidance for the choice of $ a _ 0 $, i. e, $ a _ 0 \ ge \ max \ { a ( u ) \ } / 2 $ to ensure the unconditional stability of the first order and second order schemes. the optimal error estimate is also derived for the simplified model, and numerical experiments are given to demonstrate the stability, accuracy and performance of the schemes for nonlinear diffusion equations. | arxiv:1903.11859 |
we present a multi - wavelength study of the interstellar medium in eight nearby, x - ray and optically bright, giant elliptical galaxies. using herschel pacs, we map the cold gas in the lines of [ cii ], [ oi ], and [ oib ]. additionally, we present ha + [ nii ] imaging of warm ionized gas with the soar telescope, and a study of the hot x - ray emitting plasma with chandra. all systems with extended ha emission in our sample ( 6 / 8 galaxies ) display significant [ cii ] line emission indicating the presence of cold gas. this emission is co - spatial with the ha + [ nii ] emitting nebulae and the lowest entropy x - ray emitting plasma. the entropy profiles of the hot galactic atmospheres show a clear dichotomy, with the systems displaying extended emission line nebulae having lower entropies beyond r ~ 1 kpc than the cold - gas - poor systems. we show that while the hot atmospheres of the cold - gas - poor galaxies are thermally stable outside of their innermost cores, the atmospheres of the cold - gas - rich systems are prone to cooling instabilities. this result indicates that the cold gas is produced chiefly by thermally unstable cooling from the hot phase. we show that cooling instabilities may develop more easily in rotating systems and discuss an alternative condition for thermal instability for this case. the hot atmospheres of cold - gas - rich galaxies display disturbed morphologies indicating that the accretion of clumpy multiphase gas in these systems may result in variable power output of the agn jets, potentially triggering sporadic, larger outbursts. in the two cold - gas - poor, x - ray morphologically relaxed galaxies of our sample, ngc 1399 and ngc 4472, powerful agn outbursts may have destroyed or removed most of the cold gas from the cores, allowing the jets to propagate and deposit most of their energy further out, increasing the entropy of the hot galactic atmospheres and leaving their cores relatively undisturbed. | arxiv:1310.5450 |
the measurements with the background estimation from an off - zone are widely used in astrophysics, accelerator physics and other areas. usually, the expected number of the background events in the off - zone and in the on - zone is known with a limited precision. this fact should be included as a systematic uncertainty. in this note an overview of the statistical methods which estimate the range and the significance of the measured signal is done. the method which includes a systematic uncertainty is developed for the on / off - zone measurements and compared with other existing methods. | arxiv:1303.5195 |
with the increasing inference cost of machine learning models, there is a growing interest in models with fast and efficient inference. recently, an approach for learning logic gate networks directly via a differentiable relaxation was proposed. logic gate networks are faster than conventional neural network approaches because their inference only requires logic gate operators such as nand, or, and xor, which are the underlying building blocks of current hardware and can be efficiently executed. we build on this idea, extending it by deep logic gate tree convolutions, logical or pooling, and residual initializations. this allows scaling logic gate networks up by over one order of magnitude and utilizing the paradigm of convolution. on cifar - 10, we achieve an accuracy of 86. 29 % using only 61 million logic gates, which improves over the sota while being 29x smaller. | arxiv:2411.04732 |
through the black hole ( bh ) superradiance, ultralight bosons can form dense clouds around rotating kerr bhs. certain ultralight bosons, such as axions and axion - like particles ( promising dark matter candidates ), naturally possess self - interactions, and thus may significantly modify the dynamics of the superradiance process. previous studies on the detection or constraint of ultralight bosons through superradiance have largely neglected the self - interaction effects of bosons. in this work, we investigate the formation and evolution of self - interacting boson clouds in the full kerr spacetime during bh superradiance. using numerical methods, we compute the superradiant growth rate of boson clouds with self - interactions around kerr bhs and quantitatively evaluate how the self - interaction strength of scalar bosons affects the growth rate. we also assess the evolution of the bh ' s mass and spin. our results reveal that, in addition to the superradiance - imposed upper bound on the boson cloud mass, self - interactions of ultralight bosons introduce a new, lower critical mass limit, beyond which the growth rate of the boson cloud approaches zero. this implies that the superradiance process terminates earlier when self - interactions are considered. furthermore, we explore how self - interactions affect both the oscillation frequency of boson clouds in gravitational atoms and the frequency of gravitational wave ( gw ) emitted through cloud annihilation. the anticipated frequency shift could be detectable by the gw observatories. given that self - interactions substantially alter the evolution of bh superradiance, their effects can significantly relax existing constraints on scalar boson models derived from superradiance. taking the spin measurements from gw190412 and gw190517 as examples, we discuss the impact of self - interactions on constraint results in details. | arxiv:2503.10347 |
we propose a new technique, called wild binary segmentation ( wbs ), for consistent estimation of the number and locations of multiple change - points in data. we assume that the number of change - points can increase to infinity with the sample size. due to a certain random localisation mechanism, wbs works even for very short spacings between the change - points and / or very small jump magnitudes, unlike standard binary segmentation. on the other hand, despite its use of localisation, wbs does not require the choice of a window or span parameter, and does not lead to a significant increase in computational complexity. wbs is also easy to code. we propose two stopping criteria for wbs : one based on thresholding and the other based on what we term the ` strengthened schwarz information criterion '. we provide default recommended values of the parameters of the procedure and show that it offers very good practical performance in comparison with the state of the art. the wbs methodology is implemented in the r package wbs, available on cran. in addition, we provide a new proof of consistency of binary segmentation with improved rates of convergence, as well as a corresponding result for wbs. | arxiv:1411.0858 |
we performed a careful numerical analysis of the late tail behaviour of waves propagating in the schwarzschild spacetime. specifically the scalar monopole, the electromagnetic dipole and the gravitational axial quadrupole waves have been investigated. the obtained results agree with a falloff $ 1 / t ^ { 2l + 3 } $ for the general initial data and $ 1 / t ^ { 2l + 4 } $ for the initially static data. | arxiv:gr-qc/0303101 |
this paper presents a method for improved analysis of objects with an axial symmetry using x - ray computed tomography ( ct ). cylindrical coordinates about an axis fixed to the object form the most natural base to check certain characteristics of objects that contain such symmetry, as often occurs with industrial parts. the sampling grid corresponds with the object, allowing for down - sampling hence reducing the reconstruction time. this is necessary for in - line applications and fast quality inspection. with algebraic reconstruction it permits the use of a pre - computed initial volume perfectly suited to fit a series of scans where same - type objects can have different positions and orientations, as often encountered in an industrial setting. weighted back - projection can also be included when some regions are more likely subject to change, to improve stability. building on a cartesian grid reconstruction code, the feasibility of reusing the existing ray - tracers is checked against other researches in the same field. | arxiv:2005.11976 |
the decay of disoriented chiral condensates into soft pions is considered within the context of a linear sigma model. unlike earlier analytic studies, which focused on the production of pions as the sigma field rolled down toward its new equilibrium value, here we focus on the amplification of long - wavelength pion modes due to parametric resonance as the sigma field oscillates around the minimum of its potential. this process can create larger domains of pion fluctuations than the usual spinodal decomposition process, and hence may provide a viable experimental signature for chiral symmetry breaking in relativistic heavy ion collisions ; it may also better explain physically the large growth of domains found in several numerical simulations. | arxiv:hep-ph/9801307 |
in this article we look at the coarsening rate in two standard models of ostwald ripening. specifically, we look at a discrete droplet population model, which in the limit of an infinite droplet population reduces to the classical lifshitz - - slyozov - - wagner model. we also look at the cahn - - hilliard equation with constant mobility. we define the coarsening rate as $ \ beta = - ( t / f ) ( d f / d t ) $, where $ f $ is the total free energy of the system and $ t $ is time. there is a conjecture that the long - time average value of $ \ beta $ should not exceed $ 1 / 3 $ - - this result is summarized here as $ \ langle \ beta \ rangle \ leq 1 / 3 $. we explore this conjecture for the two considered models. using large - scale computational resources ( specifically, gpu computing employing thousands of threads ), we are able to construct ensembles of simulations and thereby build up a statistical picture of $ \ beta $. our results show that the droplet population model and the cahn - - hilliard equation ( asymmetric mixtures ) are demonstrably in agreement with $ \ langle \ beta \ rangle \ leq 1 / 3 $. the results for the cahn - - hilliard equation in the case of symmetric mixtures show $ \ langle \ beta \ rangle $ sometimes exceeds $ 1 / 3 $ in our simulations. however, the possibility is left open for the very long - time average values of $ \ langle \ beta \ rangle $ to be bounded above by $ 1 / 3 $. the theoretical methodology laid out in this paper sets a path for future more intensive computational studies whereby this conjecture can be explored in more depth. \ end { abstract } | arxiv:1911.03386 |
we state conditions under which the set s ( k ) of k - rational points on a del pezzo surface s of degree 1 over an infinite field k of characteristic not equal to 2 or 3 is zariski dense. for example, it suffices to require that the elliptic fibration over the projective line induced by the anticanonical map has a nodal fiber over a k - rational point. it also suffices to require the existence of a point in s ( k ) that does not lie on six exceptional curves of s and that has order 3 on its fiber of the elliptic fibration. this allows us to show that within a parameter space for del pezzo surfaces of degree 1 over the field of real numbers, the set of surfaces s defined over the field q of rational numbers for which the set s ( q ) is zariski dense, is dense with respect to the real analytic topology. we also include conditions that may be satisfied for every del pezzo surface s and that can be verified with a finite computation for any del pezzo surface s that does satisfy them. | arxiv:1212.2364 |
vision - language models ( vlms ) have demonstrated remarkable capabilities in understanding multimodal inputs and have been widely integrated into retrieval - augmented generation ( rag ) based conversational systems. while current vlm - powered chatbots can provide textual source references in their responses, they exhibit significant limitations in referencing contextually relevant images during conversations. in this paper, we introduce contextual image reference - - the ability to appropriately reference relevant images from retrieval documents based on conversation context - - and systematically investigate vlms ' capability in this aspect. we conduct the first evaluation for contextual image referencing, comprising a dedicated testing dataset and evaluation metrics. furthermore, we propose imageref - vl, a method that significantly enhances open - source vlms ' image referencing capabilities through instruction fine - tuning on a large - scale, manually curated multimodal conversation dataset. experimental results demonstrate that imageref - vl not only outperforms proprietary models but also achieves an 88 % performance improvement over state - of - the - art open - source vlms in contextual image referencing tasks. our code is available at https : / / github. com / bytedance / imageref - vl. | arxiv:2501.12418 |
over the past decade, deep learning models have exhibited considerable advancements, reaching or even exceeding human - level performance in a range of visual perception tasks. this remarkable progress has sparked interest in applying deep networks to real - world applications, such as autonomous vehicles, mobile devices, robotics, and edge computing. however, the challenge remains that state - of - the - art models usually demand significant computational resources, leading to impractical power consumption, latency, or carbon emissions in real - world scenarios. this trade - off between effectiveness and efficiency has catalyzed the emergence of a new research focus : computationally efficient deep learning, which strives to achieve satisfactory performance while minimizing the computational cost during inference. this review offers an extensive analysis of this rapidly evolving field by examining four key areas : 1 ) the development of static or dynamic light - weighted backbone models for the efficient extraction of discriminative deep representations ; 2 ) the specialized network architectures or algorithms tailored for specific computer vision tasks ; 3 ) the techniques employed for compressing deep learning models ; and 4 ) the strategies for deploying efficient deep networks on hardware platforms. additionally, we provide a systematic discussion on the critical challenges faced in this domain, such as network architecture design, training schemes, practical efficiency, and more realistic model compression approaches, as well as potential future research directions. | arxiv:2308.13998 |
the geneva seven - colour photometric system is successfully applied to the study of various astrophysical objects. it measures the slope of the paschen continuum, the balmer discontinuity, and blocking absorption due to hydrogen or metallic lines. one of its greatest strengths is its intrinsic homogeneity. a new catalogue of the available measurements was generated, 30 years after the last publication. the identifications for the individual stars were cross - checked on the basis of the gaia and 2mass catalogues. the high precision coordinates together with proper motions ( if available ) are included, for the first time, in the catalogue. special caution was exercised with binaries and high - proper - motion stars. the catalogue includes 42 911 entries of highly accurate photometry. the data of this catalogue can be used for various applications, such as new calibrations of astrophysical parameters, the standardisation of new observations, and as additional information for ongoing and forthcoming all - sky surveys, such as the transiting exoplanet survey satellite ( tess ). | arxiv:2111.04810 |
branching ratios and polarization amplitudes for b decaying to all allowed pseudoscalar, vector, axial - vector, scalar and tensor combinations of d _ s and d mesons are calculated in the isgur scora grinstein wise ( isgw ) quark model after assuming factorization. we find good agreement with other models in the literature and the limited experimental data and make predictions for as yet unseen decay modes. lattice qcd results in this area are very limited. we make phenomenological observations on decays in to d _ s ( 2317 ) and d _ s ( 2460 ) and propose tests for determining the status and mixings of the axial mesons. we use the same approach to calculate branching ratios and polarization fraction for decays in to two d type mesons. | arxiv:hep-ph/0511169 |
moir \ ' e superlattices in two - dimensional ( 2d ) van der waals ( vdw ) heterostructures provide 20 an efficient way to engineer electron band properties. the recent discovery of exotic quantum phases and their interplay in twisted bilayer graphene ( tblg ) has built this moir \ ' e system one of the most renowned condensed matter platforms ( 1 - 10 ). so far the studies of tblg has been mostly focused on the lowest two flat moir \ ' e bands at the first magic angle { \ theta } m1 ~ 1. 1 { \ deg }, leaving high - order moir \ ' e bands and magic angles largely unexplored. here we report 25 an observation of multiple well - isolated flat moir \ ' e bands in tblg close to the second magic angle { \ theta } m2 ~ 0. 5 { \ deg }, which cannot be explained without considering electron - election interactions. with high magnetic field magneto - transport measurements, we further reveal a qualitatively new, energetically unbound hofstadter butterfly spectrum in which continuously extended quantized landau level gaps cross all trivial band - gaps. the 30 connected hofstadter butterfly strongly evidences the topologically nontrivial textures of the multiple moir \ ' e bands. overall, our work provides a new perspective for understanding the quantum phases in tblg and the fractal hofstadter spectra of multiple topological bands. | arxiv:2006.13963 |
coupled oscillators are prevalent throughout the physical world. dynamical system formulations of weakly coupled oscillator systems have proven effective at capturing the properties of real - world systems. however, these formulations usually deal with the ` forward problem ' : simulating a system from known coupling parameters. here we provide a solution to the ` inverse problem ' : determining the coupling parameters from measurements. starting from the dynamic equations of a system of coupled phase oscillators, given by a nonlinear langevin equation, we derive the corresponding equilibrium distribution. this formulation leads us to the maximum entropy distribution that captures pair - wise phase relationships. to solve the inverse problem for this distribution, we derive a closed form solution for estimating the phase coupling parameters from observed phase statistics. through simulations, we show that the algorithm performs well in high dimensions ( d = 100 ) and in cases with limited data ( as few as 100 samples per dimension ). because the distribution serves as the unique maximum entropy solution for pairwise phase statistics, the distribution and estimation technique can be broadly applied to phase coupling estimation in any system of phase oscillators. | arxiv:0906.3844 |
s action formula amazingly works. | arxiv:1902.09275 |
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