text stringlengths 1 3.65k | source stringlengths 15 79 |
|---|---|
in the study of planck - scale ( " quantum - gravity induced " ) violations of lorentz symmetry, an important role was played by the deformed - electrodynamics model introduced by myers and pospelov. its reliance on conventional effective quantum field theory, and its description of symmetry - violation effects simply in terms of a four - vector with nonzero component only in the time - direction, rendered it an ideal target for experimentalists and a natural concept - testing ground for many theorists. at this point however the experimental limits on the single myers - pospelov parameter, after improving steadily over these past few years, are " super - planckian ", { \ it i. e. } they take the model out of actual interest from a conventional quantum - gravity perspective. in light of this we here argue that it may be appropriate to move on to the next level of complexity, still with vectorial symmetry violation but adopting a generic four - vector. we also offer a preliminary characterization of the phenomenology of this more general framework, sufficient to expose a rather significant increase in complexity with respect to the original myers - pospelov setup. most of these novel features are linked to the presence of spatial anisotropy, which is particularly pronounced when the symmetry - breaking vector is space - like, and they are such that they reduce the bound - setting power of certain types of observations in astrophysics. | arxiv:1003.0878 |
roderick murchison applied the new technique to rocks throughout europe and eastern north america, setting the stage for more detailed, government - funded mapping projects in later decades. midway through the 19th century, the focus of geology shifted from description and classification to attempts to understand how the surface of the earth had changed. the first comprehensive theories of mountain building were proposed during this period, as were the first modern theories of earthquakes and volcanoes. louis agassiz and others established the reality of continent - covering ice ages, and " fluvialists " like andrew crombie ramsay argued that river valleys were formed, over millions of years by the rivers that flow through them. after the discovery of radioactivity, radiometric dating methods were developed, starting in the 20th century. alfred wegener ' s theory of " continental drift " was widely dismissed when he proposed it in the 1910s, but new data gathered in the 1950s and 1960s led to the theory of plate tectonics, which provided a plausible mechanism for it. plate tectonics also provided a unified explanation for a wide range of seemingly unrelated geological phenomena. since the 1960s it has served as the unifying principle in geology. = = = evolution and inheritance = = = perhaps the most prominent, controversial, and far - reaching theory in all of science has been the theory of evolution by natural selection, which was independently formulated by charles darwin and alfred wallace. it was described in detail in darwin ' s book the origin of species, which was published in 1859. in it, darwin proposed that the features of all living things, including humans, were shaped by natural processes over long periods of time. the theory of evolution in its current form affects almost all areas of biology. implications of evolution on fields outside of pure science have led to both opposition and support from different parts of society, and profoundly influenced the popular understanding of " man ' s place in the universe ". separately, gregor mendel formulated the principles of inheritance in 1866, which became the basis of modern genetics. = = = germ theory = = = another important landmark in medicine and biology were the successful efforts to prove the germ theory of disease. following this, louis pasteur made the first vaccine against rabies, and also made many discoveries in the field of chemistry, including the asymmetry of crystals. in 1847, hungarian physician ignac fulop semmelweis dramatically reduced the occurrence of puerperal fever by simply requiring physicians to wash their hands before attending to women in childbirth. this discovery predated the | https://en.wikipedia.org/wiki/History_of_science |
thermodynamics of d = 4, n = 4 supersymmetric su ( n ) yang - mills theory is studied with particular attention on perturbative expansion at weak ` t hooft coupling regime and interpolation to strong coupling regime thereof. non - ideal gas effect to free - energy is calculated and found that leading - and next - to - leading - order corrections contribute with relative opposite sign. pade approximant method is adopted to improve fixed - order, perturbative series and is found to decrease free - energy monotonically as ` t hooft coupling parameter is increased. this may be regarded as an indication of smooth interpolation of thermodynamics between weak and strong ` t hooft coupling regimes, as suggested by maldacena ' s ads / cft correspondence. | arxiv:hep-th/9905205 |
spin - models, where the $ n $ spins interact pairwise with a $ su ( n _ f ) $ symmetry preserving hamiltonian, famously simplify in the large $ n _ f $, $ n $ limits, as derived by sachdev and ye when exploring mean - field behavior of spin - glasses. we present numerical evidence that for a large class of models, the large $ n _ f $ limit is not necessary : the same dynamical equations can describe the relaxation processes at high temperatures for a set of classical models inspired from mean - field treatments of interacting dense neutrino gases, up to times set by the radius of convergence of the perturbation series for the correlation function. after a simple rescaling of time, the dynamics display a surprising universality, being identical for any value of $ n _ f $ as long as the rank of the coupling matrix is small. as a corollary of our results, we find that the direct interaction approximation originating from the study of stochastic flows in fluid turbulence should be thought of as only a short - time approximation for generic random coupling systems. | arxiv:2504.08925 |
the ecole polytechnique and the conservatoire national des arts et metiers which was established in 1794. polytechnique is one of the grandes ecoles that have traditionally prepared technocrats to lead french government and industry, and has been one of the most privileged routes into the elite divisions of the civil service known as the " grands corps de l ' etat ". inside a french company the title of ingenieur refers to a rank in qualification and is not restricted. therefore, there are sometimes ingenieurs des ventes ( sales engineers ), ingenieur marketing, ingenieur bancaire ( banking engineer ), ingenieur recherche & developpement ( r & d engineer ), etc. = = = germany = = = in germany, the term ingenieur ( engineer ) is legally protected and may only be used by graduates of a university degree program in engineering. such degrees are offered by universities ( universitaten ), including technische universitaten ( universities of technology ) and technische hochschulen, or fachhochschulen ( universities of applied sciences ). since the bologna reforms, students receive a bachelor ' s degree ( 3 – 4 years of studies ), optionally followed by a master ' s degree ( 1 – 2 years of studies ). prior to the country adopting the bologna system, the first and only pre - doctorate degree received after completing engineering education at university was the german diplomingenieur ( dipl. - ing. ). the engineering doctorate is the doktoringenieur ( dr. - ing. ). = = = italy = = = in italy, the engineering degree and " engineer " title is delivered by polytechnic universities upon completion of 3 years of studies ( laurea ). additional master ' s degree ( 2 years ) and doctorate programs ( 3 years ) provide the title of " dottore di ricerca in ingegneria ". students that started studies in polytechnic universities before 2005 ( when italy adopted the bologna declaration ) need to complete a 5 - year program to get the engineer title. in this case the master ' s degree is obtained after 1 year of studies. only people with an engineer title can be employed as " engineers ". still, some with competence and experience in an engineering field that do not have such a title, can still be employed to perform engineering tasks as " specialist ", " assistant ", " technologist " or " technician ". but, only engineers | https://en.wikipedia.org/wiki/Engineering_education |
we present a local gluing construction for general relativistic initial data sets. the method applies to generic initial data, in a sense which is made precise. in particular the trace of the extrinsic curvature is not assumed to be constant near the gluing points, which was the case for previous such constructions. no global conditions on the initial data sets such as compactness, completeness, or asymptotic conditions are imposed. as an application, we prove existence of spatially compact, maximal globally hyperbolic, vacuum space - times without any closed constant mean curvature spacelike hypersurface. | arxiv:gr-qc/0403066 |
due to the rapid development of non - face - to - face services due to the corona virus, commerce through the internet, such as sales and reservations, is increasing very rapidly. consumers also post reviews, suggestions, or judgments about goods or services on the website. the review data directly used by consumers provides positive feedback and nice impact to consumers, such as creating business value. therefore, analysing review data is very important from a marketing point of view. our research suggests a new way to find factors for customer satisfaction through review data. we applied a method to find factors for customer satisfaction by mixing and using the data mining technique, which is a big data analysis method, and the natural language processing technique, which is a language processing method, in our research. unlike many studies on customer satisfaction that have been conducted in the past, our research has a novelty of the thesis by using various techniques. and as a result of the analysis, the results of our experiments were very accurate. | arxiv:2209.12417 |
the n - point correlation functions in single - field inflation obey a set of consistency conditions in the exact squeezed limit which are not present in multi - field models, and thus are powerful tools to distinguish between the two. however, these consistency conditions may be violated for a finite range of scales in single - field models, for example by departures from the bunch - davies state. these it excited states may be the consequence of interactions during inflation, or may be a remnant of the era that preceded inflation. in this paper we analyze the bispectrum, and show that in the regime of theoretical control the resulting signal in the squeezed limit remains undetectably small in all known models which continuously excite the state. we also show that the signal remains undetectably small if the initial state is related to the bunch - davies state by a bogoliubov transformation and the energy density in the state is small enough so that the usual slow - roll conditions are obeyed. bogoliubov states that lead to violations of the slow - roll conditions, as well as more general excited states, require more careful treatment and will be discussed in a separate publication. | arxiv:1303.1430 |
characterizing the nature of hydrodynamical transport properties in quantum dynamics provides valuable insights into the fundamental understanding of exotic non - equilibrium phases of matter. experimentally simulating infinite - temperature transport on large - scale complex quantum systems is of considerable interest. here, using a controllable and coherent superconducting quantum simulator, we experimentally realize the analog quantum circuit, which can efficiently prepare the haar - random states, and probe spin transport at infinite temperature. we observe diffusive spin transport during the unitary evolution of the ladder - type quantum simulator with ergodic dynamics. moreover, we explore the transport properties of the systems subjected to strong disorder or a tilted potential, revealing signatures of anomalous subdiffusion in accompany with the breakdown of thermalization. our work demonstrates a scalable method of probing infinite - temperature spin transport on analog quantum simulators, which paves the way to study other intriguing out - of - equilibrium phenomena from the perspective of transport. | arxiv:2310.06565 |
this paper proposes an end - to - end cnn ( convolutional neural networks ) model that uses gram modules with parameters that are approximately 1. 2mb in size to detect fake fingerprints. the proposed method assumes that texture is the most appropriate characteristic in fake fingerprint detection, and implements the gram module to extract textures from the cnn. the proposed cnn structure uses the fire module as the base model and uses the gram module for texture extraction. tensors that passed the fire module will be joined with gram modules to create a gram matrix with the same spatial size. after 3 gram matrices extracted from different layers are combined with the channel axis, it becomes the basis for categorizing fake fingerprints. the experiment results had an average detection error of 2. 61 % from the livdet 2011, 2013, 2015 data, proving that an end - to - end cnn structure with few parameters that is able to be used in fake fingerprint detection can be designed. | arxiv:1803.07830 |
disease progression models are widely used to inform the diagnosis and treatment of many progressive diseases. however, a significant limitation of existing models is that they do not account for health disparities that can bias the observed data. to address this, we develop an interpretable bayesian disease progression model that captures three key health disparities : certain patient populations may ( 1 ) start receiving care only when their disease is more severe, ( 2 ) experience faster disease progression even while receiving care, or ( 3 ) receive follow - up care less frequently conditional on disease severity. we show theoretically and empirically that failing to account for any of these disparities can result in biased estimates of severity ( e. g., underestimating severity for disadvantaged groups ). on a dataset of heart failure patients, we show that our model can identify groups that face each type of health disparity, and that accounting for these disparities while inferring disease severity meaningfully shifts which patients are considered high - risk. | arxiv:2412.16406 |
in recent work by the authors, a connection between feynman ' s path integral and fourier integral operator $ \ zeta $ - functions has been established as a means of regularizing the vacuum expectation values in quantum field theories. however, most explicit examples using this regularization technique to date, do not consider gauge fields in detail. here, we address this gap by looking at some well - known physical examples of quantum fields from the fourier integral operator $ \ zeta $ - function point of view. | arxiv:1902.09926 |
consider a $ 2n $ - dimensional symplectic vector space $ e $ over an arbitrary field $ \ mathbb { f } $. given a contraction map $ f : \ wedge ^ n e \ rightarrow \ wedge ^ { n - 2 } e $ such that the lagrangian - - grassmannian $ l ( n, 2n ) = g ( n, 2n ) \ cap { \ mathbb p } ( \ ker f ) $, where $ \ wedge ^ r e $ denotes the $ r $ - th exterior power of $ e $ and $ { \ mathbb p } ( \ ker f ) $ is the projectivization of $ \ ker f $. in this paper, for a symplectic vector space $ e $ of dimension $ n = 6 $, we prove that the surjectivity of the contraction map $ f : \ wedge ^ { 6 } e \ rightarrow \ wedge ^ { 4 } e $ depends on the characteristic of the base field and we calculate the codimension of the linear section $ { \ mathbb p } ( \ ker f ) \ subseteq { \ mathbb p } ( \ wedge ^ { 6 } e ) $ for any characteristic. | arxiv:1701.08242 |
we consider the problem of mapping with ultra - high angular resolution using a space - ground radio interferometer with a space antenna in a high orbit, whose apogee height exceeds the radius of the earth by a factor of ten. in this case, a multielement interferometer essentially degenerates into a two - element interferometer. the degeneracy of the close - phase relations prevents the use of standard methods for hybrid mapping and self - calibration for the correct reconstruction of images. we propose a new phaseless mapping method based on methods for the reconstruction of images in the complete absence of phase information, using only the amplitudes of the spatial - coherence function of the source. in connection with this problem, we propose a new method for the reliable solution of the phase problem, based on optimizing information - carrying nonlinear functionals, in particular, the shannon entropy. results of simulations of mapping radio sources with various structures with ultra - high angular resolution in the framework of the radioastron mission are presented. | arxiv:astro-ph/0512570 |
the manual assessment and grading of student writing is a time - consuming yet critical task for teachers. recent developments in generative ai, such as large language models, offer potential solutions to facilitate essay - scoring tasks for teachers. in our study, we evaluate the performance and reliability of both open - source and closed - source llms in assessing german student essays, comparing their evaluations to those of 37 teachers across 10 pre - defined criteria ( i. e., plot logic, expression ). a corpus of 20 real - world essays from year 7 and 8 students was analyzed using five llms : gpt - 3. 5, gpt - 4, o1, llama 3 - 70b, and mixtral 8x7b, aiming to provide in - depth insights into llms ' scoring capabilities. closed - source gpt models outperform open - source models in both internal consistency and alignment with human ratings, particularly excelling in language - related criteria. the novel o1 model outperforms all other llms, achieving spearman ' s $ r =. 74 $ with human assessments in the overall score, and an internal consistency of $ icc =. 80 $. these findings indicate that llm - based assessment can be a useful tool to reduce teacher workload by supporting the evaluation of essays, especially with regard to language - related criteria. however, due to their tendency for higher scores, the models require further refinement to better capture aspects of content quality. | arxiv:2411.16337 |
at large baryon number density, it is likely that the ground state of qcd is a color - flavor - locked phase with a k0 condensate. the cfl + k0 phase is known to support superconducting vortex strings, and it has been previously suggested that it may also support vortons, which are superconducting vortex rings. we reexamine the question of the stability of vortons, taking into account electromagnetic effects, which make leading - order contributions to vorton dynamics but were not investigated in previous work. we find that current - carrying and electrically charged vortons can be stabilized either by their angular momentum, by coulomb repulsion, or by a combination of both effects. | arxiv:1102.4795 |
currently, many countries are considering the introduction of tracing software on mobile smartphones with the main purpose to inform and alarm the mobile app user. here, we demonstrate that, in addition to alarming and informing, mobile tracing can detect nearly all users that are infected by sars - cov - 2. our algorithm betis ( bayesian estimation for tracing infection states ) makes use of self - reports of the user ' s health status. then, betis guarantees that almost all sars - cov - 2 infections of the group of users can be detected. furthermore, betis estimates the virus prevalence in the whole population, consisting of users and non - users. betis is based on a hidden markov epidemic model and recursive bayesian filtering. the potential that mobile tracing apps, in addition to medical testing and quarantining, can eradicate covid - 19 may persuade citizens to trade - off privacy against public health. | arxiv:2006.14285 |
galaxies have clearly evolved since the universe was 1 gyr old, but methods to trace and quantify this evolution are still in their infancy. in this paper i demonstrate that with the careful use of a ` physical morphology ' it is possible to determine quantitatively how the process of galaxy evolution is occurring out to z = 4. using a system of parameters that traces star formation and galaxy interactions, i show how distinct galaxy populations at high - z can be identified in deep high - resolution optical and nir images. these tools are also used to measure a potential merger fraction of galaxies from 0 < z < 4. if these methods are reliable, as is suggested by a local galaxy calibration, the merger fraction of galaxies scales as ( 1 + z ) ^ { 2. 1 + / - 0. 5 }, peaks near z = 2, and declines thereafter. i also discuss how this system is likely part of the ultimate physical classification of galaxies. | arxiv:astro-ph/0012008 |
recently it has been shown that the $ \ alpha $ - sun density $ h ( x ) $ [ { \ it j. math. anal. appl. }, { \ bf 527 } ( 2023 ), p. 127371 ] which interpolates between the fr { \ ' e } chet density and that of the positive, stable distributions whose density is given by a fox $ h $ - function, has a mellin transform involving an infinite product of ratios of incomplete beta functions. we develop systematic, but asymptotic, approximations for such products and consequently for the behaviour of the density as $ x \ to 0 + $ which complement the recent exact form for this by simon [ { \ it electron. commun. probab. }, { \ bf 28 } ( 2023 ) p. 1 - 13 ]. the systematic expansion is an example of a power product expansion, and in our case we derive bounds and estimates which show that this expansion is not convergent and thus only yields an asymptotic expansion. | arxiv:2306.10655 |
in this work, we propose new adaptive step size strategies that improve several stochastic gradient methods. our first method ( stops ) is based on the classical polyak step size ( polyak, 1987 ) and is an extension of the recent development of this method for the stochastic optimization - sps ( loizou et al., 2021 ), and our second method, denoted grads, rescales step size by " diversity of stochastic gradients ". we provide a theoretical analysis of these methods for strongly convex smooth functions and show they enjoy deterministic - like rates despite stochastic gradients. furthermore, we demonstrate the theoretical superiority of our adaptive methods on quadratic objectives. unfortunately, both stops and grads depend on unknown quantities, which are only practical for the overparametrized models. to remedy this, we drop this undesired dependence and redefine stops and grads to stop and grad, respectively. we show that these new methods converge linearly to the neighbourhood of the optimal solution under the same assumptions. finally, we corroborate our theoretical claims by experimental validation, which reveals that grad is particularly useful for deep learning optimization. | arxiv:2208.05287 |
a phase space treatment of special relativity of quantum systems is developed. in this approach a quantum particle remains localized if subject to inertial transformations, the localization occurring in a finite phase space area. unlike non - relativistic transformations, relativistic transformations generally distort the phase space distribution function, being equivalent to aberrations in optics. | arxiv:0803.0972 |
to achieve universal quantum computation via general fault - tolerant schemes, stabilizer operations must be supplemented with other non - stabilizer quantum resources. motivated by this necessity, we develop a resource theory for magic quantum channels to characterize and quantify the quantum " magic " or non - stabilizerness of noisy quantum circuits. for qudit quantum computing with odd dimension $ d $, it is known that quantum states with non - negative wigner function can be efficiently simulated classically. first, inspired by this observation, we introduce a resource theory based on completely positive - wigner - preserving quantum operations as free operations, and we show that they can be efficiently simulated via a classical algorithm. second, we introduce two efficiently computable magic measures for quantum channels, called the mana and thauma of a quantum channel. as applications, we show that these measures not only provide fundamental limits on the distillable magic of quantum channels, but they also lead to lower bounds for the task of synthesizing non - clifford gates. third, we propose a classical algorithm for simulating noisy quantum circuits, whose sample complexity can be quantified by the mana of a quantum channel. we further show that this algorithm can outperform another approach for simulating noisy quantum circuits, based on channel robustness. finally, we explore the threshold of non - stabilizerness for basic quantum circuits under depolarizing noise. | arxiv:1903.04483 |
short - term future of automated driving can be imagined as a hybrid scenario in which both automated and human - driven vehicles co - exist in the same environment. in order to address the needs of such road configuration, many technology solutions such as vehicular communication and predictive control for automated vehicles have been introduced in the literature. both aforementioned solutions rely on driving data of the human driver. in this work, we investigate the currently available driving datasets and introduce a real - world maneuver - based driving dataset that is collected during our urban driving data collection campaign. we also provide a model that embeds the patterns in maneuver - specific samples. such model can be employed for classification and prediction purposes. | arxiv:2005.13781 |
a 3d ising model with a purely plaquette, 4 - spin interaction displays a planar flip symmetry intermediate between a global and a gauge symmetry and as a consequence has a highly degenerate low temperature phase and no standard magnetic order parameter. this plaquette hamiltonian is a particular case of a family of 3d gonihedric ising models defined by savvidy and wegner. an anisotropic variant of the the purely plaquette gonihedric model, originally discussed as the " fuki - nuke " model by suzuki, is non - trivially equivalent to a stack of 2d ising models, each of which can magnetize independently at the phase transition point. consideration of this anisotropic model suggests that a suitable order parameter in the isotropic case may also be constructed using a form of planar magnetization, in which nearest neighbour correlators summed over planes replace a sum over spin values. we conduct monte - carlo simulations to investigate this and related candidate order parameters in a toy model of gonihedric ground states, the fuki - nuke model and the isotropic plaquette gonihedric model itself. | arxiv:1207.3174 |
event - by - event ( ebe ) multiplicity \ fll and \ cor amongst the charged particles emitted in the forward - backward symmetric pseudorapidity ( \ et ) windows of varying widths and positions are investigated by analyzing the experimental data on $ ^ { 197 } $ au - agbr collisions at 11. 6a gev / c. the findings are compared with the predictions of relativistic transport model, \ urq and independent particle emission ( or mixed event ) model. it is observed that the \ fll in ebe mean pseudorapidity values and those reflected from the \ fll strength measure, \ ( \ phi \ ) are relatively higher as compared to those expected from the statistically independent particle emission model. the study of the variance, \ ( \ sigma _ c ^ 2 \ ) of a suitably defined forward - backward asymmetry variable \ ( c \ ) as a function of \ et window width and position indicates the presence of strong short - range correlations, which might arise due to isotropic decay of cluster - like objects either in forward or backward \ et region. furthermore, analyses of events having \ ring and \ jet substructures, carried out separately, suggest that the major contribution to the observed \ fll in the data sample are due to ring - like events, while the contributions from the \ jet events appear to be rather small. the observed difference in the behavior of correlation strengths from the two types of events might be due to the enhanced emission of cherenkov gluons, giving rise to the \ ring substructure. the mixed event analysis further confirms that the observed \ fll are the distinct feature of the data, which disappear after event mixing. | arxiv:2305.01973 |
we discuss two classes of exact ( in $ \ a ' $ ) string solutions described by conformal sigma models. they can be viewed as two possibilities of constructing a conformal model out of the non - conformal one based on the metric of a $ d $ - dimensional homogeneous $ g / h $ space. the first possibility is to introduce two extra dimensions ( one space - like and one time - like ) and to impose the null killing symmetry condition on the resulting $ 2 + d $ dimensional metric. in the case when the ` ` transverse " model is $ n = 2 $ supersymmetric and the $ g / h $ space is k \ " ahler - einstein the resulting metric - dilaton background can be found explicitly. the second possibility - which is realised in the sigma models corresponding to $ g / h $ conformal theories - is to deform the metric, introducing at the same time a non - trivial dilaton and antisymmetric tensor backgrounds. the expressions for the metric and dilaton in this case are derived using the operator approach in which one identifies the equations for marginal operators of conformal theory with the linearised ( near a background ) expressions for the ` $ \ b $ - functions '. equivalent results are then reproduced in the direct field - theoretical approach based on computing first the effective action of the $ g / h $ gauged wzw model and then solving for the $ 2d $ gauge field. both the bosonic and the supersymmetric cases are discussed. ( to be published in the proceedings of the 26 workshop ` ` from superstrings to supergravity ", erice, 5 - 12 december, 1992. ) | arxiv:hep-th/9303054 |
extreme ultraviolet ( euv ) solar flare emissions evolve in time as the emitting plasma heats and then cools. although accurately modeling this evolution has been historically difficult, especially for empirical relationships, it is important for understanding processes at the sun, as well as for their influence on planetary atmospheres. with a goal to improve empirical flare models, a new simple empirical expression is derived to predict how cool emissions will evolve based on the evolution of a hotter emission. this technique is initially developed by studying 12 flares in detail observed by the euv variability experiment ( eve ) onboard the solar dynamics observatory ( sdo ). then, over 1100 flares observed by eve are analyzed to validate these relationships. the cargill and enthalpy based thermal evolution of loops ( ebtel ) flare cooling models are used to show that this empirical relationship implies the energy radiated by a population of hotter formed ions is approximately proportional to the energy exciting a population of cooler formed ions emitting when the peak formation temperatures of the two lines are up to 72 % of each other and above 2 mk. these results have practical implications for improving flare irradiance empirical modeling and for identifying key emission lines for future monitoring of flares for space weather operations ; and also provide insight into the cooling processes of flare plasma. | arxiv:1703.02995 |
in this paper we study the spectral property of a fokker - planck operator with potential. by virtue of a multiplier method inspired by nicolas lerner, we obtain new compactness criteria for its resolvent, involving the control of the positive eigenvalues of the hessian matrix of the potential. | arxiv:1510.01567 |
we propose an entanglement - enhanced sensing scheme that is robust against spatially inhomogeneous always - on ising interactions. our strategy is to tailor coherent quantum dynamics employing the hilbert - space fragmentation ( hsf ), a recently recognized mechanism that evades thermalization in kinetically constrained many - body systems. specifically, we analytically show that the emergent hsf caused by strong ising interactions enables us to design a stable state where part of the spins is effectively decoupled from the rest of the system. using the decoupled spins as a probe to measure a transverse field, we demonstrate that the heisenberg limited sensitivity is achieved without suffering from thermalization. | arxiv:2211.09567 |
we study an interactive live streaming scenario where multiple peers pull streams of the same free viewpoint video that are synchronized in time but not necessarily in view. in free viewpoint video, each user can periodically select a virtual view between two anchor camera views for display. the virtual view is synthesized using texture and depth videos of the anchor views via depth - image - based rendering ( dibr ). in general, the distortion of the virtual view increases with the distance to the anchor views, and hence it is beneficial for a peer to select the closest anchor views for synthesis. on the other hand, if peers interested in different virtual views are willing to tolerate larger distortion in using more distant anchor views, they can collectively share the access cost of common anchor views. given anchor view access cost and synthesized distortion of virtual views between anchor views, we study the optimization of anchor view allocation for collaborative peers. we first show that, if the network reconfiguration costs due to view - switching are negligible, the problem can be optimally solved in polynomial time using dynamic programming. we then consider the case of non - negligible reconfiguration costs ( e. g., large or frequent view - switching leading to anchor - view changes ). in this case, the view allocation problem becomes np - hard. we thus present a locally optimal and centralized allocation algorithm inspired by lloyd ' s algorithm in non - uniform scalar quantization. we also propose a distributed algorithm with guaranteed convergence where each peer group independently make merge - and - split decisions with a well - defined fairness criteria. the results show that depending on the problem settings, our proposed algorithms achieve respective optimal and close - to - optimal performance in terms of total cost, and outperform a p2p scheme without collaborative anchor selection. | arxiv:1211.4767 |
the article is devoted to the investigation of the nonlinear effects in a system of the coupled longitudinal - torsional parametric vibrations of a rotating rod. constructed and investigated mathematical model, based on which we calculated the resonance conditions of the nonlinear oscillations and found the ratio of the parameters that require changing of the sign of the coefficient in front of the term defining the possible reverse of torsional vibrations. the latter is a new phenomenon, a special mode, where the parametric action in the form of longitudinal vibrations at one end of the rod ( for example periodic strikes in the rod ' s end with a certain frequency ) can lead to torsional vibrations due to the nonlinear parametric interaction of oscillations. in the context of this, the reverse leads to control not only the rotation parameters, but also the direction of rotation, and there are possible torsional oscillations, which can be used in precision mechanics devices. | arxiv:1803.04135 |
in this study, we investigate the imprints of $ c \! p $ violation in certain $ \ eta $ muonic decays that could arise within the standard model effective field theory. in particular, we study the sensitivities that could be reached at redtop, a proposed $ \ eta $ facility. after estimating the bounds that the neutron edm places, we find still viable to discover signals of $ c \! p $ violation via the muons ' polarization in $ \ eta \ to \ mu ^ + \ mu ^ - $ decays at redtop, with a single effective operator as its plausible source. | arxiv:1810.13228 |
using stellar population models, we predicted that the dark energy survey ( des ) - due to its special combination of area ( 5000 deg. sq. ) and depth ( $ i = 24. 3 $ ) - would be in the position to detect massive ( $ \ gtrsim 10 ^ { 11 } $ m $ _ { \ odot } $ ) galaxies at $ z \ sim 4 $. we confront those theoretical calculations with the first $ \ sim 150 $ deg. sq. of des data reaching nominal depth. from a catalogue containing $ \ sim 5 $ million sources, $ \ sim26000 $ were found to have observed - frame $ g - r $ vs $ r - i $ colours within the locus predicted for $ z \ sim 4 $ massive galaxies. we further removed contamination by stars and artefacts, obtaining 606 galaxies lining up by the model selection box. we obtained their photometric redshifts and physical properties by fitting model templates spanning a wide range of star formation histories, reddening and redshift. key to constrain the models is the addition, to the optical des bands $ g $, $ r $, $ i $, $ z $, and $ y $, of near - ir $ j $, $ h $, $ k _ { s } $ data from the vista hemisphere survey. we further applied several quality cuts to the fitting results, including goodness of fit and a unimodal redshift probability distribution. we finally select 233 candidates whose photometric redshift probability distribution function peaks around $ z \ sim4 $, have high stellar masses ( $ \ log ( $ m $ ^ { * } $ / m $ _ { \ odot } ) \ sim 11. 7 $ for a salpeter imf ) and ages around 0. 1 gyr, i. e. formation redshift around 5. these properties match those of the progenitors of the most massive galaxies in the local universe. this is an ideal sample for spectroscopic follow - up to select the fraction of galaxies which is truly at high redshift. these initial results and those at the survey completion, which we shall push to higher redshifts, will set unprecedented constraints on galaxy formation, evolution, and the re - ionisation epoch. | arxiv:1811.12422 |
electric currents play an important role in the energy balance of the plasma in the solar atmosphere. they are also indicative of non - potential magnetic fields and magnetic reconnection. unfortunately, the direct measuring of electric currents has traditionally been riddled with inaccuracies. we study how accurately we can infer electric currents under different scenarios. we carry out increasingly complex inversions of the radiative transfer equation for polarized light applied to stokes profiles synthesized from radiative three - dimensional magnetohydrodynamic ( mhd ) simulations. the inversion yields the magnetic field vector, $ { \ bf b } $, from which the electric current density, $ { \ bf j } $, is derived by applying ampere ' s law. we find that the retrieval of the electric current density is only slightly affected by photon noise or spectral resolution. however, the retrieval steadily improves as the stokes inversion becomes increasingly elaborated. in the least complex case ( a milne - eddington - like inversion applied to a single spectral region ), it is possible to determine the individual components of the electric current density ( $ j _ { \ rm x } $, $ j _ { \ rm y } $, $ j _ { \ rm z } $ ) with an accuracy of $ \ sigma = 0. 90 - 1. 00 $ dex, whereas the modulus ( $ \ | { \ bf j } \ | $ ) can only be determined with $ \ sigma = 0. 75 $ dex. in the most complicated case ( with multiple spectral regions, a large number of nodes, tikhonov vertical regularization, and magnetohydrostatic equilibrium ), these numbers improve to $ \ sigma = 0. 70 - 0. 75 $ dex for the individual components and $ \ sigma = 0. 5 $ dex for the modulus. moreover, in regions where the magnetic field is above 300 gauss, $ \ | { \ bf j } \ | $ can be inferred with an accuracy of $ \ sigma = 0. 3 $ dex. in general, the $ x $ and $ y $ components of the electric current density are retrieved slightly better than the $ z $ component. | arxiv:2211.07593 |
in this paper, we propose a new framework for solving state estimation problems with an additional sparsity - promoting $ l _ 1 $ - regularizer term. we first formulate such problems as minimization of the sum of linear or nonlinear quadratic error terms and an extra regularizer, and then present novel algorithms which solve the linear and nonlinear cases. the methods are based on a combination of the iterated extended kalman smoother and variable splitting techniques such as alternating direction method of multipliers ( admm ). we present a general algorithmic framework for variable splitting methods, where the iterative steps involving minimization of the nonlinear quadratic terms can be computed efficiently by iterated smoothing. due to the use of state estimation algorithms, the proposed framework has a low per - iteration time complexity, which makes it suitable for solving a large - scale or high - dimensional state estimation problem. we also provide convergence results for the proposed algorithms. the experiments show the promising performance and speed - ups provided by the methods. | arxiv:1903.08605 |
we examine the time evolution of the entanglement spectrum of a small subsystem of a non - integrable spin chain following a quench from a product state. we identify signatures in this entanglement spectrum of the distinct dynamical velocities ( related to entanglement and operator spreading ) that control thermalization. we show that the onset of level repulsion in the entanglement spectrum occurs on different timescales depending on the " entanglement energy ", and that this dependence reflects the shape of the operator front. level repulsion spreads across the entire entanglement spectrum on timescales close to when the mutual information between individual spins at the ends of the subsystem reaches its maximum ; this timescale is much shorter than that for full thermalization of the subsystem. we provide an analytical understanding of this phenomenon and show supporting numerical data for both random unitary circuits and a microscopic hamiltonian. | arxiv:1901.04444 |
we present accurate measurements of carrier - envelope phase effects on ionisation of the noble gases with few - cycle laser pulses. the experimental apparatus is calibrated by using atomic hydrogen data to remove any systematic offsets and thereby obtain accurate cep data on other generally used noble gases such as ar, kr and xe. experimental results for h are well supported by exact tdse theoretical simulations however significant differences are observed in case of noble gases. | arxiv:1601.02277 |
gromov proposed to extract the ( differential ) geometric content of a sub - riemannian space exclusively from its carnot - carath \ ' eodory distance. one of the most striking features of a regular sub - riemannian space is that it has at any point a metric tangent space with the algebraic structure of a carnot group, hence a homogeneous lie group. siebert characterizes homogeneous lie groups as locally compact groups admitting a contracting and continuous one - parameter group of automorphisms. siebert result has not a metric character. in these notes i show that sub - riemannian geometry may be described by about 12 axioms, without using any a priori given differential structure, but using dilation structures instead. dilation structures bring forth the other intrinsic ingredient, namely the dilations, thus blending gromov metric point of view with siebert algebraic one. | arxiv:1206.3093 |
we provide a mathematical analysis of two models advocated in the theoretical and experimental condensed matter literature : the two dimensional spin - $ 1 / 2 $ quantum walk and the kagome quantum network ; they apply to occurrence of stable quantum currents. this illustrates the theory of stable absolutely continuous spectrum and stable currents developed in \ cite { abj5 }. | arxiv:1908.11689 |
anomaly inspection plays an important role in industrial manufacture. existing anomaly inspection methods are limited in their performance due to insufficient anomaly data. although anomaly generation methods have been proposed to augment the anomaly data, they either suffer from poor generation authenticity or inaccurate alignment between the generated anomalies and masks. to address the above problems, we propose anomalydiffusion, a novel diffusion - based few - shot anomaly generation model, which utilizes the strong prior information of latent diffusion model learned from large - scale dataset to enhance the generation authenticity under few - shot training data. firstly, we propose spatial anomaly embedding, which consists of a learnable anomaly embedding and a spatial embedding encoded from an anomaly mask, disentangling the anomaly information into anomaly appearance and location information. moreover, to improve the alignment between the generated anomalies and the anomaly masks, we introduce a novel adaptive attention re - weighting mechanism. based on the disparities between the generated anomaly image and normal sample, it dynamically guides the model to focus more on the areas with less noticeable generated anomalies, enabling generation of accurately - matched anomalous image - mask pairs. extensive experiments demonstrate that our model significantly outperforms the state - of - the - art methods in generation authenticity and diversity, and effectively improves the performance of downstream anomaly inspection tasks. the code and data are available in https : / / github. com / sjtuplayer / anomalydiffusion. | arxiv:2312.05767 |
on april 15, 2016, the kumamoto earthquake ( mw 7. 3 ) occurred in japan with no warning signals. global navigation satellite system ( gnss ) receivers provide useful information on disturbances in ionosphere by calculating the changes in total electron content ( tec ), which is the number of electrons in ionosphere. here we show our recently proposed correlation analysis of tec data which can detect the pre - seismic ionospheric anomalies from the public gnss data. our method detected the ionospheric anomaly several tens of minutes before the 2016 kumamoto earthquake near its epicenter. furthermore, we gave an indicator to distinguish between the pre - seismic tec anomalies and the medium scale traveling ionospheric disturbances ( mstids ) by calculating the anomalous area rates. these results support the hypothesis for existence of the preceding phenomena before large earthquakes. | arxiv:1612.05667 |
we provide the metric, the gravitino fields and the gauge fields to all orders in the fermionic zero modes for d = 5 and d = 4, n = 2 gauged supergravity solutions starting from non - extremal ads - - schwarzschild black holes. we compute the brown - york stress - - energy tensor on the boundary of ads _ 5 / ads _ 4 spaces and we discuss some implications of the fermionic corrections to perfect fluid interpretation of the boundary theory. the complete non - linear solution, which we denote as fermionic wig, is achieved by acting with supersymmetry transformations upon the supergravity fields and that expansion naturally truncates at some order in the fermionic zero modes. | arxiv:1207.0686 |
we report the first direct observation of collective quantum fluctuations in a continuous field. shot - to - shot atom number fluctuations in small sub - volumes of a weakly interacting ultracold atomic 1d cloud are studied using \ textit { in situ } absorption imaging and statistical analysis of the density profiles. in the cloud centers, well in the \ textit { quantum quasicondensate } regime, the ratio of chemical potential to thermal energy is $ \ mu / k _ b t \ simeq4 $, and, owing to high resolution, up to 20 % of the microscopically observed fluctuations are quantum phonons. within a non - local analysis at variable observation length, we observe a clear deviation from a classical field prediction, which reveals the emergence of dominant quantum fluctuations at short length scales, as the thermodynamic limit breaks down. | arxiv:1112.4199 |
retrieval - augmented generative ( rag ) models enhance large language models ( llms ) by integrating external knowledge bases, improving their performance in applications like fact - checking and information searching. in this paper, we demonstrate a security threat where adversaries can exploit the openness of these knowledge bases by injecting deceptive content into the retrieval database, intentionally changing the model ' s behavior. this threat is critical as it mirrors real - world usage scenarios where rag systems interact with publicly accessible knowledge bases, such as web scrapings and user - contributed data pools. to be more realistic, we target a realistic setting where the adversary has no knowledge of users ' queries, knowledge base data, and the llm parameters. we demonstrate that it is possible to exploit the model successfully through crafted content uploads with access to the retriever. our findings emphasize an urgent need for security measures in the design and deployment of rag systems to prevent potential manipulation and ensure the integrity of machine - generated content. | arxiv:2406.19417 |
stationary entanglement in a four - mode optomechanical system, especially under roomtemperature, is discussed. in this scheme, when the coupling strengths between the two target modes and the mechanical resonator are equal, the results cannot be explained by the bogoliubov mode - based scheme. this is related to the idea of quantum - mechanics - free subspace, which plays an important role when the thermal noise of the mechanical modes is considered. significantly prominent steady - state entanglement can be available under room - temperature. | arxiv:1608.02392 |
automatic code completion helps improve developers ' productivity in their programming tasks. a program contains instructions expressed via code statements, which are considered as the basic units of program execution. in this paper, we introduce autosc, which combines program analysis and the principle of software naturalness to fill in a partially completed statement. autosc benefits from the strengths of both directions, in which the completed code statement is both frequent and valid. autosc is first trained on a large code corpus to derive the templates of candidate statements. then, it uses program analysis to validate and concretize the templates into syntactically and type - valid candidate statements. finally, these candidates are ranked by using a language model trained on the lexical form of the source code in the code corpus. our empirical evaluation on the large datasets of real - world projects shows that autosc achieves 38. 9 - 41. 3 % top - 1 accuracy and 48. 2 - 50. 1 % top - 5 accuracy in statement completion. it also outperforms a state - of - the - art approach from 9x - 69x in top - 1 accuracy. | arxiv:1911.07781 |
we show that a ksvz axion with a decay constant in the phenomenologically allowed range can be obtained in certain $ e _ 8 \ times e _ 8 $ heterotic string models. these models have an enhanced symmetry locus in the moduli space, and a non - universal, kahler moduli dependent fayet - iliopoulos term which vanishes at this locus. close to this locus the fayet - iliopoulos term is small and can lead to an axion decay constant significantly lower than the string scale. in this way, the no - go arguments of svrcek and witten, which are based on a universal, dilaton - dependent fayet - iliopoulos term, can be avoided. the relevant axion originates from phases of bundle moduli which correspond to deformations away from the enhanced symmetry locus. we construct an explicit example, based on a heterotic line bundle standard model, with all the required ingredients. | arxiv:1412.8696 |
vortices ( flows with closed elliptic streamlines ) are exact nonlinear solutions to the compressible euler equation. in this contribution, we use differential geometry to derive the transformations between cartesian and elliptic coordinates, and show that in elliptic coordinates a constant vorticity flow reduces to $ \ dot { \ mu } = 0 $ and $ \ dot { \ nu } = { \ rm const } $ along the streamline $ \ mu _ 0 $ that matches the vortex eccentricity. | arxiv:2108.04013 |
in this paper, we introduce bar - natan homology for null homologous links in \ mathbb { rp } ^ 3 over the field of two elements. it is a deformation of the khovanov homology in \ mathbb { rp } ^ 3 defined by asaeda, przytycki and sikora. we also define an s - invariant from this deformation using the same recipe as for links in s ^ 3, and prove some genus bound using it. the key ingredient is the notion of twisted orientation for null homologous links and cobordisms in \ mathbb { rp } ^ 3. | arxiv:2307.11461 |
a measurement of beauty hadron production at mid - rapidity in proton - lead collisions at a nucleon - nucleon centre - of - mass energy $ \ sqrt { s _ { \ rm nn } } = 5. 02 $ tev is presented. the semi - inclusive decay channel of beauty hadrons into j / $ \ psi $ is considered, where the j / $ \ psi $ mesons are reconstructed in the dielectron decay channel at mid - rapidity down to transverse momenta of 1. 3 gev / $ c $. the $ { \ rm { b \ overline { b } } } $ production cross section at mid - rapidity, $ { \ rm d } \ sigma _ { \ rm { b \ overline { b } } } / { \ rm d } y $, and the total cross section extrapolated over full phase space, $ \ sigma _ { \ rm { b \ overline { b } } } $, are obtained. this measurement is combined with results on inclusive j / $ \ psi $ production to determine the prompt j / $ \ psi $ cross sections. the results in p - pb collisions are then scaled to expectations from pp collisions at the same centre - of - mass energy to derive the nuclear modification factor $ r _ { \ rm ppb } $, and compared to models to study possible nuclear modifications of the production induced by cold nuclear matter effects. $ r _ { \ rm ppb } $ is found to be smaller than unity at low $ p _ { \ rm t } $ for both j / $ \ psi $ coming from beauty hadron decays and prompt j / $ \ psi $. | arxiv:1802.00765 |
given a target function $ h $ to minimize or a target gibbs distribution $ \ pi _ { \ beta } ^ 0 \ propto e ^ { - \ beta h } $ to sample from in the low temperature, in this paper we propose and analyze langevin monte carlo ( lmc ) algorithms that run on an alternative landscape as specified by $ h ^ f _ { \ beta, c, 1 } $ and target a modified gibbs distribution $ \ pi ^ f _ { \ beta, c, 1 } \ propto e ^ { - \ beta h ^ f _ { \ beta, c, 1 } } $, where the landscape of $ h ^ f _ { \ beta, c, 1 } $ is a transformed version of that of $ h $ which depends on the parameters $ f, \ beta $ and $ c $. while the original log - sobolev constant affiliated with $ \ pi ^ 0 _ { \ beta } $ exhibits exponential dependence on both $ \ beta $ and the energy barrier $ m $ in the low temperature regime, with appropriate tuning of these parameters and subject to assumptions on $ h $, we prove that the energy barrier of the transformed landscape is reduced which consequently leads to polynomial dependence on both $ \ beta $ and $ m $ in the modified log - sobolev constant associated with $ \ pi ^ f _ { \ beta, c, 1 } $. this yield improved total variation mixing time bounds and improved convergence toward a global minimum of $ h $. we stress that the technique developed in this paper is not only limited to lmc and is broadly applicable to other gradient - based optimization or sampling algorithms. | arxiv:2302.03973 |
we use inelastic neutron scattering to study temperature dependence of the paramagnetic spin excitations in iron pnictide bafe $ _ 2 $ as $ _ 2 $ throughout the brillouin zone. in contrast to a conventional local moment heisenberg system, where paramagnetic spin excitations are expected to have a lorentzian function centered at zero energy transfer, the high - energy ( $ \ hbar \ omega > 100 $ mev ) paramagnetic spin excitations in bafe $ _ 2 $ as $ _ 2 $ exhibit spin - wave - like features up to at least 290 k ( $ t = 2. 1t _ n $ ). furthermore, we find that the sizes of the fluctuating magnetic moments $ < m ^ 2 > \ approx 3. 6 \ \ mu ^ 2 _ b $ per fe are essentially temperature independent from the af ordered state at $ 0. 05t _ n $ to $ 2. 1t _ n $, which differs considerably from the temperature dependent fluctuating moment observed in the iron chalcogenide fe $ _ { 1. 1 } $ te [ i. a. zaliznyak { \ it et al. }, phys. rev. lett. { \ bf 107 }, 216403 ( 2011 ). ]. these results suggest unconventional magnetism and strong electron correlation effects in bafe $ _ 2 $ as $ _ 2 $. | arxiv:1209.6271 |
context. solar coronal jets seen in euv are ubiquitous on the sun, have been found in and at the edges of active regions, at the boundaries of coronal holes, and in the quiet sun. jets have various shapes, sizes, brightness, velocities and duration in time, which complicates their detection by automated algorithms. so far, solar jets reported in the heliophysics event knowledgebase ( hek ) have been mostly reported by humans looking for them in the data, with different levels of precision regarding their timing and positions. aims. we create a catalogue of solar jets observed in euv at 304 { \ aa } containing precise and consistent information on the jet timing, position and extent. methods. we designed a citizen science project, " solar jet hunter ", on the zooniverse platform, to analyze euv observations at 304 { \ aa } from the solar dynamic observatory / atmospheric imaging assembly ( sdo / aia ). we created movie strips for regions of the sun in which jets have been reported in hek and ask the volunteers to 1 ) confirm the presence of at least one jet in the data and 2 ) report the timing, position and extent of the jet. results. we report here the design of the project and the results obtained after the analysis of data from 2011 to 2016. 365 " coronal jet " events from hek served as input for the citizen science project, equivalent to more than 120, 000 images distributed into 9, 689 " movie strips ". classification by the citizen scientists resulted with only 21 % of the data containing a jet, and 883 individual jets being identified. conclusions. we demonstrate how citizen science can enhance the analysis of solar data with the example of solar jet hunter. the catalogue of jets thus created is publicly available and will enable statistical studies of jets and related phenomena. this catalogue will also be used as a training set for machines to learn to recognize jets in further data sets. | arxiv:2309.14871 |
we introduce and study the concept of a reversible transfer of the quantum state of two internally - translationally entangled fragments, formed by molecular dissociation, to a photon pair. the transfer is based on intracavity stimulated raman adiabatic passage and it requires a combination of processes whose principles are well established. | arxiv:quant-ph/0111093 |
monolayers of colloidal particles at oil - water interfaces readily crystalize owing to electrostatic repulsion, which is often mediated through the oil. however, little attempts exist to control it using oil - soluble electrolytes. we probe the interactions amongst charged hydrophobic micospheres confined at a water / hexadecane interface and show that repulsion can be continuously tuned over orders of magnitude upon introducing minor amounts of an organic salt into the oil. our results show that charged groups at the particle / oil interface are subject to an associative discharging mechanism, analogous to the charge regulation kinetics observed for charged colloids in non - polar solvents. | arxiv:2305.01929 |
we study the set of lines that meet a fixed line and are tangent to two spheres and classify the configurations consisting of a single line and three spheres for which there are infinitely many lines tangent to the three spheres that also meet the given line. all such configurations are degenerate. the path to this result involves the interplay of some beautiful and intricate geometry of real surfaces in 3 - space, complex algebraic geometry, explicit computation and graphics. | arxiv:math/0304346 |
we present a systematic classification and analysis of possible pairing instabilities in graphene - based moir \ ' e superlattices. motivated by recent experiments on twisted double - bilayer graphene showing signs of triplet superconductivity, we analyze both singlet and triplet pairing separately, and describe how these two channels behave close to the limit where the system is invariant under separate spin rotations in the two valleys, realizing an su ( 2 ) $ _ + $ $ \ times $ su ( 2 ) $ _ - $ symmetry. further, we discuss the conditions under which singlet and triplet can mix via two nearly degenerate transitions, and how the different pairing states behave when an external magnetic field is applied. the consequences of the additional microscopic or emergent approximate symmetries relevant for superconductivity in twisted bilayer graphene and abc trilayer graphene on hexagonal boron nitride are described in detail. we also analyze which of the pairing states can arise in mean - field theory and study the impact of corrections coming from ferromagnetic fluctuations. for instance, we show that, close to the parameters of mean - field theory, a nematic mixed singlet - triplet state emerges. our study illustrates that graphene superlattices provide a rich platform for exotic superconducting states, and allow for the admixture of singlet and triplet pairing even in the absence of spin - orbit coupling. | arxiv:1906.03258 |
mechanical and elastic properties of materials are among the most fundamental quantities for many engineering and industrial applications. here, we present a formulation that is efficient and accurate for calculating the elastic and bending rigidity tensors of crystalline solids, leveraging interatomic force constants and long - wavelength perturbation theory. crucially, in the long - wavelength limit, lattice vibrations induce macroscopic electric fields which further couple with the propagation of elastic waves, and a separate treatment on the long - range electrostatic interactions is thereby required to obtain elastic properties under the appropriate electrical boundary conditions. a cluster expansion of the charge density response and dielectric screening function in the long - wavelength limit has been developed to efficiently extract multipole and dielectric tensors of arbitrarily high order. we implement the proposed method in a first - principles framework and perform extensive validations on silicon, nacl, gaas and rhombohedral batio $ _ 3 $ as well as monolayer graphene, hexagonal bn, mos $ _ 2 $ and inse, obtaining good to excellent agreement with other theoretical approaches and experimental measurements. notably, we establish that multipolar interactions up to at least octupoles are necessary to obtain the accurate short - circuit elastic tensor of bulk materials, while higher orders beyond octupole interactions are required to converge the bending rigidity tensor of 2d crystals. the present approach greatly simplifies the calculations of bending rigidities and will enable the automated characterization of the mechanical properties of novel functional materials. | arxiv:2412.18482 |
recent radial velocity observations have indicated that jovian - type planets can exist in moderately close binary star systems. numerical simulations of the dynamical stability of terrestrial - class planets in such environments have shown that, in addition to their giant planets, these systems can also harbor earth - like objects. in this paper, we study the late stage of terrestrial planet formation in such binary - planetary systems, and present the results of the simulations of the formation of earth - like bodies in their habitable zones. we consider a circumprimary disk of moon - to mars - sized objects and numerically integrate the orbits of these bodies at the presence of the jovian - type planet of the system and for different values of the mass, semimajor axis, and orbital eccentricity of the secondary star. results indicate that, earth - like objects, with substantial amounts of water, can form in the habitable zone of the primary star. simulations also indicate that, by transferring angular momentum from the secondary star to protoplanetary objects, the giant planet of the system plays a key role in the radial mixing of these bodies and the water contents of the final terrestrial planets. we will discuss the results of our simulation and show that the formation of habitable planets in binary - planetary systems is more probable in binaries with moderate to large perihelia. | arxiv:astro-ph/0702706 |
a cluster id assignment scheme labels each cluster of a clustering with a distinct id. the goal of id assignment is semantic id stability, which means that, whenever possible, a cluster for the same underlying concept as that of a historical cluster should ideally receive the same id as the historical cluster. semantic id stability allows the users of a clustering to refer to a concept ' s cluster with an id that is stable across clusterings / time. this paper treats the problem of evaluating the relative merits of id assignment schemes. in particular, it considers a historical clustering with id assignments, and a new clustering with ids assigned by a baseline and an experiment. it produces metrics that characterize both the magnitude and the quality of the id assignment diffs between the baseline and the experiment. that happens by transforming the problem of cluster id assignment into a problem of cluster membership, and evaluating it with abcde. abcde is a sophisticated and scalable technique for evaluating differences in cluster membership in real - world applications, where billions of items are grouped into millions of clusters, and some items are more important than others. the paper also describes several generalizations to the basic evaluation setup for id assignment schemes. for example, it is fairly straightforward to evaluate changes that simultaneously mutate cluster memberships and cluster ids. the ideas are generously illustrated with examples. | arxiv:2409.18254 |
pseudorandom sequences are used extensively in communications and remote sensing. correlation provides one measure of pseudorandomness, and low correlation is an important factor determining the performance of digital sequences in applications. we consider the problem of constructing pairs $ ( f, g ) $ of sequences such that both $ f $ and $ g $ have low mean square autocorrelation and $ f $ and $ g $ have low mean square mutual crosscorrelation. we focus on aperiodic correlation of binary sequences, and review recent contributions along with some historical context. | arxiv:1806.04707 |
filter pruning is widely used to reduce the computation of deep learning, enabling the deployment of deep neural networks ( dnns ) in resource - limited devices. conventional hard filter pruning ( hfp ) method zeroizes pruned filters and stops updating them, thus reducing the search space of the model. on the contrary, soft filter pruning ( sfp ) simply zeroizes pruned filters, keeping updating them in the following training epochs, thus maintaining the capacity of the network. however, sfp, together with its variants, converges much slower than hfp due to its larger search space. our question is whether sfp - based methods and hfp can be combined to achieve better performance and speed up convergence. firstly, we generalize sfp - based methods and hfp to analyze their characteristics. then we propose a gradually hard filter pruning ( ghfp ) method to smoothly switch from sfp - based methods to hfp during training and pruning, thus maintaining a large search space at first, gradually reducing the capacity of the model to ensure a moderate convergence speed. experimental results on cifar - 10 / 100 show that our method achieves the state - of - the - art performance. | arxiv:2011.03170 |
we begin with a prior observation by one of us that thomas precession in the nonrelativistic limit of the dirac equation may be attributed to a nonabelian berry vector potential. we ask what object produces the nonabelian potential in parameter space, in the same sense that the abelian vector potential arising in the adiabatic transport of a nondegenerate level is produced by a monopole, ( centered at the point where the level becomes degenerate with another ), as shown by berry. we find that it is a { \ em meron }, an object in four euclidean dimensions with instanton number $ { 1 \ over 2 } $, centered at the point where the doubly degenerate positive and negative energy levels of the dirac equation become fourfold degenerate. | arxiv:hep-th/9403076 |
an $ n \ times n $ sign pattern $ s $, which is a matrix with entries $ 0, +, - $, is called spectrally arbitrary if any monic real polynomial of degree $ n $ can be realized as a characteristic polynomial of a matrix obtained by replacing the non - zero elements of $ s $ by numbers of the corresponding signs. a sign pattern $ s $ is said to be a superpattern of those matrices that can be obtained from $ s $ by replacing some of the non - zero entries by zeros. we develop a new technique that allows us to prove spectral arbitrariness of sign patterns for which the previously known " nilpotent jacobian " method does not work. our approach leads us to solutions of numerous open problems known in the literature. in particular, we provide an example of a sign pattern $ s $ and its superpattern $ s ' $ such that $ s $ is spectrally arbitrary but $ s ' $ is not, disproving a conjecture proposed in 2000 by drew, johnson, olesky, and van den driessche. | arxiv:1612.05818 |
in the last two decades, bayesian inference has become commonplace in astronomy. at the same time, the choice of algorithms, terminology, notation, and interpretation of bayesian inference varies from one sub - field of astronomy to the next, which can lead to confusion to both those learning and those familiar with bayesian statistics. moreover, the choice varies between the astronomy and statistics literature, too. in this paper, our goal is two - fold : ( 1 ) provide a reference that consolidates and clarifies terminology and notation across disciplines, and ( 2 ) outline practical guidance for bayesian inference in astronomy. highlighting both the astronomy and statistics literature, we cover topics such as notation, specification of the likelihood and prior distributions, inference using the posterior distribution, and posterior predictive checking. it is not our intention to introduce the entire field of bayesian data analysis - - rather, we present a series of useful practices for astronomers who already have an understanding of the bayesian " nuts and bolts " and wish to increase their expertise and extend their knowledge. moreover, as the field of astrostatistics and astroinformatics continues to grow, we hope this paper will serve as both a helpful reference and as a jumping off point for deeper dives into the statistics and astrostatistics literature. | arxiv:2302.04703 |
the merger of a binary neutron star system is suggested as the central engine of short gamma - ray bursts ( sgrbs ). for the merger process, simulations predict that magnetic field is amplified beyond magnetar field strength by kelvin - helmholtz instabilities. with the large area telescope ( lat ), bursts have been detected that show a temporally extended component in coincidence with a short - lasting peak at the end of the prompt phase. we show that the presence of these lat components in a sgrb could provide evidence of magnetic field amplification in the neutron star merger. | arxiv:1701.01184 |
target tracking entails the estimation of the evolution of the target state over time, namely the target trajectory. different from the classical state space model, our series of studies, including this paper, model the collection of the target state as a stochastic process ( sp ) that is further decomposed into a deterministic part which represents the trend of the trajectory and a residual sp representing the residual fitting error. subsequently, the tracking problem is formulated as a learning problem regarding the trajectory sp for which a key part is to estimate a trajectory fot ( t - fot ) best fitting the measurements in time series. for this purpose, we consider the polynomial t - fot and address the regularized polynomial t - fot optimization employing two distinct regularization strategies seeking trade - off between the accuracy and simplicity. one limits the order of the polynomial and then the best choice is determined by grid searching in a narrow, bounded range while the other adopts $ \ ell _ 0 $ norm regularization for which the hybrid newton solver is employed. simulation results obtained in both single and multiple maneuvering target scenarios demonstrate the effectiveness of our approaches. | arxiv:2502.16121 |
defects and dopant atoms in solid state materials are a promising platform for realizing single photon sources and quantum memories, which are the basic building blocks of quantum repeaters needed for long distance quantum networks. in particular, trivalent erbium ( er $ ^ { 3 + } $ ) is of interest because it couples c - band telecom optical transitions with a spin - based memory platform. in order to produce quantum repeaters at the scale required for a quantum internet, it is imperative to integrate these necessary building blocks with mature and scalable semiconductor processes. in this work, we demonstrate the optical isolation of single er $ ^ { 3 + } $ ions in cmos - compatible titanium dioxide ( tio $ _ 2 $ ) thin films monolithically integrated on a silicon - on - insulator ( soi ) photonics platform. our results demonstrate a first step toward the realization of a monolithically integrated and scalable quantum photonics package based on er $ ^ { 3 + } $ doped thin films. | arxiv:2406.02810 |
we investigate the combined evolution of the dipolar surface magnetic field ( b $ _ { s } $ ) and the spin - period ( p $ _ s $ ) of known magnetars and high magnetic field ( b $ _ s $ $ \ gtrsim 10 ^ { 13 } $ ~ g ) radio pulsars. we study the long term behaviour of these objects assuming a simple ohmic dissipation of the magnetic field. identifying the regions ( in the p $ _ s $ - b $ _ s $ plane ) in which these neutron stars would likely move into, before crossing the death - line to enter the pulsar graveyard, we comment upon the possible connection between the magnetars and other classes of neutron stars. | arxiv:2201.05248 |
we study emission of photoelectrons from plasmonic nanoparticles into surrounding matrix. we consider two mechanisms of the photoelectric effect from nanoparticles - surface and volume ones, and use models of these two effects which allow us to obtain analytical results for the photoelectron emission rates from nanoparticle. calculations have been done for the step potential at surface of spherical nanoparticle, and the simple model for the hot electron cooling have been used. we highlight the effect of the discontinuity of the dielectric permittivity at the nanoparticle boundary in the surface mechanism, which leads to substantial ( by 5 times ) increase of photoelectron emission rate from nanoparticle compared to the case when such discontinuity is absent. for plasmonic nanoparticle, a comparison of two mechanisms of the photoeffect was done for the first time and showed that surface photoeffect, at least, does not concede the volume one, which agrees with results for the flat metal surface first formulated by tamm and schubin in their pioneering development of quantum - mechanical theory of photoeffect in 1931. in accordance with our calculations, this predominance of the surface effect is a result of effective cooling of hot carriers, during their propagation from volume of the nanoparticle to its surface in the scenario of the volume mechanism. taking into account both mechanisms is essential in development of devices based on the photoelectric effect and in usage of hot electrons from plasmonic nanoantenna. | arxiv:1312.1508 |
in many areas of science and engineering, computer simulations are widely used as proxies for physical experiments, which can be infeasible or unethical. such simulations can often be computationally expensive, and an emulator can be trained to efficiently predict the desired response surface. a widely - used emulator is the gaussian process ( gp ), which provides a flexible framework for efficient prediction and uncertainty quantification. standard gps, however, do not capture structured sparsity on the underlying response surface, which is present in many applications, particularly in the physical sciences. we thus propose a new hierarchical shrinkage gp ( hiergp ), which incorporates such structure via cumulative shrinkage priors within a gp framework. we show that the hiergp implicitly embeds the well - known principles of effect sparsity, heredity and hierarchy for analysis of experiments, which allows our model to identify structured sparse features from the response surface with limited data. we propose efficient posterior sampling algorithms for model training and prediction, and prove desirable consistency properties for the hiergp. finally, we demonstrate the improved performance of hiergp over existing models, in a suite of numerical experiments and an application to dynamical system recovery. | arxiv:2302.00755 |
robot navigation in dynamic environments shared with humans is an important but challenging task, which suffers from performance deterioration as the crowd grows. in this paper, multi - subgoal robot navigation approach based on deep reinforcement learning is proposed, which can reason about more comprehensive relationships among all agents ( robot and humans ). specifically, the next position point is planned for the robot by introducing history information and interactions in our work. firstly, based on subgraph network, the history information of all agents is aggregated before encoding interactions through a graph neural network, so as to improve the ability of the robot to anticipate the future scenarios implicitly. further consideration, in order to reduce the probability of unreliable next position points, the selection module is designed after policy network in the reinforcement learning framework. in addition, the next position point generated from the selection module satisfied the task requirements better than that obtained directly from the policy network. the experiments demonstrate that our approach outperforms state - of - the - art approaches in terms of both success rate and collision rate, especially in crowded human environments. | arxiv:2205.02003 |
the bubble of nothing is a solution to einstein ' s equations where a circle shrinks and pinches off smoothly. as such, it is one of the simplest examples of a dynamical cobordism to nothing. we take a first step in studying how this solution transforms under t - duality in bosonic string theory. applying buscher ' s rules reveals that the dual solution features a singular, strongly coupled core, with a circle blowing - up rather than pinching off. this naive approach to t - duality solely accounts for the zero - modes of the fields after dimensional reduction on the circle. for this reason, we argue that this is not the full picture that the t - dual solution should depend non - trivially on the dual circle. we point out evidence to this effect both in the gravity description and on the worldsheet. a more complete description of the t - dual object would require a full - fledged sigma model for the bubble of nothing. nevertheless, inspired by similar examples in the literature, we detail one possible scenario where the stringy bubble of nothing is mediated by closed string tachyon condensation and we discuss its t - duality. | arxiv:2312.09291 |
reflection states are introduced in the vertical and horizontal modules of the ding - iohara - miki ( dim ) algebra ( quantum toroidal $ \ mathfrak { gl } _ 1 $ ). webs of dim representations are in correspondence with $ ( p, q ) $ - web diagrams of type iib string theory, under the identification of the algebraic intertwiner of awata, feigin and shiraishi with the refined topological vertex. extending the correspondence to the vertical reflection states, it is possible to engineer the $ \ mathcal { n } = 1 $ quiver gauge theory of d - type ( with unitary gauge groups ). in this way, the nekrasov instanton partition function is reproduced from the evaluation of expectation values of intertwiners. this computation leads to the identification of the vertical reflection state with the orientifold plane of string theory. we also provide a translation of this construction in the iqbal - kozcaz - vafa refined topological vertex formalism. | arxiv:1709.01954 |
the chromatic number of a graph is the minimum $ k $ such that the graph has a proper $ k $ - coloring. there are many coloring parameters in the literature that are proper colorings that also forbid bicolored subgraphs. some examples are $ 2 $ - distance coloring, acyclic coloring, and star coloring, which forbid a bicolored path on three vertices, bicolored cycles, and a bicolored path on four vertices, respectively. this notion was first suggested by gr \ " unbaum in 1973, but no specific name was given. we revive this notion by defining an $ h $ - avoiding $ k $ - coloring to be a proper $ k $ - coloring that forbids a bicolored subgraph $ h $. when considering the class $ \ mathcal c $ of graphs with no $ f $ as an induced subgraph, it is not hard to see that every graph in $ \ mathcal c $ has bounded chromatic number if and only if $ f $ is a complete graph of size at most two. we study this phenomena for the class of graphs with no $ f $ as a subgraph for $ h $ - avoiding coloring. we completely characterize all graphs $ f $ where the class of graphs with no $ f $ as a subgraph has bounded $ h $ - avoiding chromatic number for a large class of graphs $ h $. as a corollary, our main result implies a characterization of graphs $ f $ where the class of graphs with no $ f $ as a subgraph has bounded star chromatic number. we also obtain a complete characterization for the acyclic chromatic number. | arxiv:1812.01279 |
this paper is concerned with the mean curvature flow, which describes the dynamics of a hypersurface whose normal velocity is determined by local mean curvature. we present a cartesian grid - based method for solving mean curvature flows in two and three space dimensions. the present method embeds a closed hypersurface into a fixed cartesian grid and decomposes it into multiple overlapping subsets. for each subset, extra tangential velocities are introduced such that marker points on the hypersurface only moves along grid lines. by utilizing an alternating direction implicit ( adi ) - type time integration method, the subsets are evolved alternately by solving scalar parabolic partial differential equations on planar domains. the method removes the stiffness using a semi - implicit scheme and has no high - order stability constraint on time step size. numerical examples in two and three space dimensions are presented to validate the proposed method. | arxiv:2309.05963 |
this study examines how housing sector volatilities affect real estate investment trust ( reit ) equity return in the united states. i argue that unexpected changes in housing variables can be a source of aggregate housing risk, and the first principal component extracted from the volatilities of u. s. housing variables can predict the expected reit equity returns. i propose and construct a factor - based housing risk index as an additional factor in asset price models that uses the time - varying conditional volatility of housing variables within the u. s. housing sector. the findings show that the proposed housing risk index is economically and theoretically consistent with the risk - return relationship of the conditional intertemporal capital asset pricing model ( icapm ) of merton ( 1973 ), which predicts an average maximum of 5. 6 percent of risk premium in reit equity return. in subsample analyses, the positive relationship is not affected by sample periods ' choice but shows higher housing risk beta values for the 2009 - 18 sample period. the relationship remains significant after controlling for vix, fama - french three factors, and a broad set of macroeconomic and financial variables. moreover, the proposed housing beta also accurately forecasts u. s. macroeconomic and financial conditions. | arxiv:2107.10455 |
we study 2d $ su ( n ) $ qcd with an adjoint dirac fermion. assuming that the ir limit of the massless theory is captured by a wzw coset cft, we show that this cft can be decomposed into a sum of distinct cfts, each representing a superselection sector ( universe ) of the gauge theory corresponding to different flux tube sectors. the cfts describing each universe are related by non - invertible topological lines that exhibit a mixed anomaly with the $ \ mathbb { z } ^ { ( 1 ) } _ n $ 1 - form symmetry. these symmetries exist along the entire rg flow thereby implying deconfinement of the massless theory. we begin by outlining the general features of the model for arbitrary $ n $ and then provide a detailed analysis for $ n = 2 $ and $ n = 3 $. in these specific cases, we explicitly determine the ir partition function, identify the symmetries, and explore relevant deformations. based on these findings and in alignment with various previous studies, we propose a phase diagram for the massive $ su ( 2 ) $ gauge theory and calculate its confining string tension. | arxiv:2409.17989 |
sex work, or the exchange of sexual services for money or goods, is ubiquitous across eras and cultures. however, the practice of selling sex is often hidden due to stigma and the varying legal status of sex work. online platforms that sex workers use to advertise services have become an increasingly important means of studying a market that is largely hidden. although prior literature has primarily shed light on sex work from a public health or policy perspective ( focusing largely on female sex workers ), there are few studies that empirically research patterns of service provision in online sex work. this study investigated the determinants of pricing and popularity in the market for commercial sexual services online by using data from the largest uk network of online sexual services, a platform that is the industry - standard for sex workers. while the size of these influences varies across genders, nationality, age and the services provided are shown to be primary drivers of rates and popularity in sex work. | arxiv:2006.15648 |
we search the fermi - lat photon database for an extended gamma - ray emission which could be associated with any of the 581 previously detected gamma - ray bursts ( grbs ) visible to the fermi - lat. for this purpose we compare the number of photons with energies e > 100 mev and e > 1 gev which arrived in the first 1500 seconds after the burst from the same region, to the expected background. we require that the expected number of false detections does not exceed 0. 05 for the entire search and find the high - energy emission in 19 bursts, four of which ( grb 081009, grb 090720b, grb 100911 and grb 100728a ) were previously unreported. the first three are detected at energies above 100 mev, while the last one shows a statistically significant signal only above 1 gev. | arxiv:1104.5476 |
the need for autonomous robot systems in both the service and the industrial domain is larger than ever. in the latter, the transition to small batches or even " batch size 1 " in production created a need for robot control system architectures that can provide the required flexibility. such architectures must not only have a sufficient knowledge integration framework. it must also support autonomous mission execution and allow for interchangeability and interoperability between different tasks and robot systems. we introduce skiros2, a skill - based robot control platform on top of ros. skiros2 proposes a layered, hybrid control structure for automated task planning, and reactive execution, supported by a knowledge base for reasoning about the world state and entities. the scheduling formulation builds on the extended behavior tree model that merges task - level planning and execution. this allows for a high degree of modularity and a fast reaction to changes in the environment. the skill formulation based on pre -, hold - and post - conditions allows to organize robot programs and to compose diverse skills reaching from perception to low - level control and the incorporation of external tools. we relate skiros2 to the field and outline three example use cases that cover task planning, reasoning, multisensory input, integration in a manufacturing execution system and reinforcement learning. | arxiv:2306.17030 |
passive acoustics can provide a variety of capabilities with applications in oceanographic research and maritime situational awareness. in this paper, we develop a method for the navigation of autonomous underwater vehicles ( auvs ) in shallow water. our approach relies on passively recorded signals from acoustic sources of opportunities ( soos ). by making use of the waveguide invariant, a measurement of the range to the soo is extracted from the spectrogram of a single hydrophone. range extraction requires knowledge of the range rate, i. e., the radial velocity between the soo and auv, computed from the pressure fields at different time intervals. a particle - based navigation filter fuses the range measurements with the auv ' s internal velocity and heading measurements. as a result, the position error, which would otherwise increase over time, can be bounded. the ability to compute the range rate and range measurements from the pressure field measured using a single hydrophone is demonstrated on real data from the swellex - 96 experiment. the capability of the developed navigation filter is shown based on synthetic data generated by the normal mode program kraken. | arxiv:2306.06426 |
this paper develops a formal account of causal explanation, grounded in a theory of conversational pragmatics, and inspired by the interventionist idea that explanation is about asking and answering what - if - things - had - been - different questions. we illustrate the fruitfulness of the account, relative to previous accounts, by showing that widely recognised explanatory virtues emerge naturally, as do subtle empirical patterns concerning the impact of norms on causal judgments. this shows the value of a communication - first approach to explanation : getting clear on explanation ' s communicative dimension is an important prerequisite for philosophical work on explanation. the result is a simple but powerful framework for incorporating insights from the cognitive sciences into philosophical work on explanation, which will be useful for philosophers or cognitive scientists interested in explanation. | arxiv:2505.03732 |
laboratory experiments with high - energetic heavy - ion collisions offer the opportunity to explore fundamental properties of nuclear matter, such as the high - density equation - of - state, which governs the structure and dynamics of cosmic objects and phenomena like neutron stars, supernova explosions, and neutron star mergers. a particular goal and challenge of the experiments is to unravel the microscopic degrees - of - freedom of strongly interaction matter at high density, including the search for phase transitions, which may feature a region of phase coexistence and a critical endpoint. as the theory of strong interaction is not able to make firm predictions for the structure and the properties of matter high baryon chemical potentials, the scientific progress in this field is driven by experimental results. the mission of future experiments at fair and nica, which will complement the running experimental programs at gsi, cern, and rhic, is to explore new diagnostic probes, which never have been measured before at collision energies, where the highest net - baryon densities will be created. the most promising observables, which are expected to shed light on the nature of high - density qcd matter, comprise the collective flow of identified particles including multi - strange ( anti - ) hyperons, fluctuations and correlations, lepton pairs, and charmed particles. in the following, the perspectives for experiments in the nica energy range will be discussed. | arxiv:2005.13856 |
heterodyne detectors as phase - insensitive ( pi ) devices have found important applications in precision measurements such as space - based gravitational - wave ( gw ) observation. however, the output signal of a pi heterodyne detector is supposed to suffer from signal - to - noise ratio ( snr ) degradation due to image band vacuum and imperfect quantum efficiency. here we show that the snr degradation can be overcome when the image band vacuum is quantum correlated with the input signal. we calculate the noise figure of the detector and prove the feasibility of heterodyne detection with enhanced noise performance through quantum correlation. this work should be of great interest to ongoing space - borne gw signal searching experiments. | arxiv:2103.01764 |
this report analyses data collected from last. fm and used to create a real - time recommendation system. we collected over 2m songs and 1m tags and 372k user ' s listening habits. we characterize users ' profiles : age, playcount, friends, gender and country. we characterized song, artist and tag popularity, genres of songs. additionally we evaluated the co - occurrence of songs in users ' histories, which can be used to compute similarity between songs. | arxiv:1605.08486 |
quasi - one - dimensional magnet nicl $ _ 2 \ cdot $ 4sc ( nh $ _ 2 $ ) $ _ 2 $, usually abbreviated as dtn, does not order at zero field down to $ t = 0 $ : due to the strong single - ion anisotropy of the " easy plane " type acting on $ s = 1 $ ni $ ^ { 2 + } $ ions, the $ s _ z = 0 $ ground state is separated from $ s _ z = \ pm 1 $ excitations by an energy gap. once the magnetic field is applied along the main anisotropy axis, the gap closes at $ b _ { c1 } = 2. 18 $ t and the field - induced antiferromagnetic order arises. the low - energy excitations spectrum of this field - induced ordered state includes two branches of excitations, one of them have to be a gapless goldstone mode. recent studies of excitations spectrum in a field - induced ordered state of dtn ( t. soldatov et. al, phys. rev. b 101, 104410 ( 2020 ) ) have revealed that goldstone mode became gapped as magnetic field deviates from the main symmetry axis. this paper proposes simple description of antiferromagnetic resonance modes of quasi - one - dimensional quantum $ s = 1 $ magnet with strong single - ion anisotropy. the approach used is based on a combination of the strong coupling model for the anisotropic spin chain with the conventional mean - field model of antiferromagnetic resonance. the resulting model fits to the known experimental results without additional tuning parameters. | arxiv:2011.02715 |
ensuring safety in autonomous systems with vision - based control remains a critical challenge due to the high dimensionality of image inputs and the fact that the relationship between true system state and its visual manifestation is unknown. existing methods for learning - based control in such settings typically lack formal safety guarantees. to address this challenge, we introduce a novel semi - probabilistic verification framework that integrates reachability analysis with conditional generative adversarial networks and distribution - free tail bounds to enable efficient and scalable verification of vision - based neural network controllers. next, we develop a gradient - based training approach that employs a novel safety loss function, safety - aware data - sampling strategy to efficiently select and store critical training examples, and curriculum learning, to efficiently synthesize safe controllers in the semi - probabilistic framework. empirical evaluations in x - plane 11 airplane landing simulation, carla - simulated autonomous lane following, and f1tenth lane following in a physical visually - rich miniature environment demonstrate the effectiveness of our method in achieving formal safety guarantees while maintaining strong nominal performance. our code is available at https : / / github. com / xhowenma / spvt. | arxiv:2503.00191 |
in a 1987 letter, serre proves that the systems of hecke eigenvalues arising from mod $ p $ modular forms ( of fixed level $ \ gamma ( n ) $ coprime to $ p $, and any weight $ k $ ) are the same as those arising from functions $ \ omega ( n ) \ to \ bar { \ mathbb f } _ p $, where $ \ omega ( n ) $ is some double quotient of $ d ^ \ times ( \ mathbb a _ f ) $ and $ d $ is the unique quaternion algebra over $ \ mathbb q $ ramified at $ \ { p, \ infty \ } $. we present an algorithm which then computes these hecke eigenvalues on the quaternion side in a combinatorial manner. | arxiv:2211.04708 |
question answering ( qa ), giving correct answers to questions, is a popular task, but we test reverse question answering ( rqa ) : for an input answer, give a question with that answer. past work tests qa and rqa separately, but we test them jointly, comparing their difficulty, aiding benchmark design, and checking reasoning consistency. we run 16 llms on qa and rqa with trivia questions / answers, revealing : 1 ) versus qa, llms are much less accurate in rqa for numerical answers, but slightly more accurate in rqa for textual answers ; 2 ) llms often answer their own invalid questions from rqa accurately in qa, so rqa errors are not from knowledge gaps alone ; 3 ) rqa errors correlate with question difficulty and inversely correlate with answer frequencies in the dolma corpus ; and 4 ) llms struggle to provide valid multi - hop questions. by finding question and answer types that lead to rqa errors, we suggest improvements for llm reasoning. | arxiv:2410.15512 |
we show that the inclusion of counter rotating terms, usually dropped, in the interaction hamiltonian of the electric dipole of a two level atom with an electromagnetic field leads to significant modification of the splitting of an atomic beam known as optical stern gerlach effect which now acquires a fine structure. | arxiv:0709.3902 |
we consider load scheduling on constrained continuous - time linear dynamical systems, such as automated irrigation and other distribution networks. the requested loads are rigid, i. e., the shapes cannot be changed. hence, it is only possible to shift the order back - and - forth in time to arrive at a feasible schedule. we present a numerical algorithm based on using log - barrier functions to include the state constraints in the social cost function ( i. e., an appropriate function of the scheduling delays ). this algorithm requires a feasible initialization. further, in another algorithm, we treat the state constraints as soft constraints and heavily penalize the constraint violations. this algorithm can even be initialized at an infeasible point. the applicability of both these numerical algorithms is demonstrated on an automated irrigation network with two pools and six farms. | arxiv:1509.05499 |
the design of astronomical hardware operating at the diffraction limit requires optimization of physical optical simulations of the instrument with respect to desired figures of merit, such as throughput or astrometric accuracy. these systems can be high dimensional, with highly nonlinear relationships between outputs and the adjustable parameters of the hardware. in this series of papers we present and apply dlux, an open - source end - to - end differentiable optical modelling framework. automatic differentiation enables not just efficient high - dimensional optimization of astronomical hardware designs, but also bayesian experimental design directly targeting the precision of experimental outcomes. automatic second derivatives enable the exact and numerically stable calculation of parameter covariance forecasts, and higher derivatives of these enable direct optimization of these forecasts. we validate this method against analytic theory and illustrate its utility in evaluating the astrometric precision of a parametrized telescope model, and the design of a diffractive pupil to achieve optimal astrometric performance for exoplanet searches. the source code and tutorial software are open source and publicly available, targeting researchers who may wish to harness dlux for their own optical simulation problems. | arxiv:2406.08704 |
the bogomolov multiplier is a group theoretical invariant isomorphic to the unramified brauer group of a given quotient space. we derive a homological version of the bogomolov multiplier, prove a hopf - type formula, find a five term exact sequence corresponding to this invariant, and describe the role of the bogomolov multiplier in the theory of central extensions. a new description of the bogomolov multiplier of a nilpotent group of class two is obtained. we define the bogomolov multiplier within k - theory and show that proving its triviality is equivalent to solving a long - standing problem posed by bass. an algorithm for computing the bogomolov multiplier is developed. | arxiv:1203.3190 |
the relation among spacetime supersymmetry algebras and superbrane actions is further explored. it is proved that $ sl ( 2, \ br ) $ belongs to the automorphism group of the $ { \ cal n } = 2 $ d = 10 type iib superpoincar \ ' e algebra. its so ( 2 ) subgroup is identified with a non - local so ( 2 ) transformation found in hep - th / 9806161. performing t - duality, new non - local transformations are found in type iia relating, among others, bion configurations with two d2 - branes intersecting at a point. its m - theory origin is explained. these results show that part of the superpoincar \ ' e algebra automorphism group might be realized on the field theory as non - local transformations. | arxiv:hep-th/0010242 |
the ever - growing number of large spectroscopic survey programs has increased the importance of fast and reliable methods with which to determine precise stellar parameters. some of these methods are highly dependent on correct spectroscopic calibrations. the goal of this work is to obtain a new spectroscopic calibration for a fast estimate of teff and [ fe / h ] for a wide range of stellar spectral types. we used spectra from a joint sample of 708 stars, compiled from 451 fgk dwarfs and 257 gk - giant stars. we used homogeneously determined spectroscopic stellar parameters to derive temperature calibrations using a set of selected ew line - ratios, and [ fe / h ] calibrations using a set of selected fei lines. we have derived 322 ew line - ratios and 100 fei lines that can be used to compute teff and [ fe / h ], respectively. we show that these calibrations are effective for fgk dwarfs and gk - giant stars in the following ranges : 4500 k < teff < 6500 k, 2. 5 < logg < 4. 9 dex, and - 0. 8 < [ fe / h ] < 0. 5 dex. the new calibration has a standard deviation of 74 k for teff and 0. 07 dex for [ fe / h ]. we use four independent samples of stars to test and verify the new calibration, a sample of 56 giant stars, a sample composed of gaia fgk benchmark stars, a sample of 36 gk - giant stars of the dr1 of the gaia - eso survey, and a sample of 582 fgk - dwarf stars. we also provide a new computer code, getcal, for automatically producing new calibration files based on any new sample of stars. | arxiv:1608.08392 |
the authors study smooth lines on projective planes over the algebra c of complex numbers, the algebra c ^ 1 of double numbers, and the algebra c ^ 0 of dual numbers. in the space rp ^ 5, to these smooth lines there correspond families of straight lines describing point three - dimensional tangentially degenerate submanifolds x ^ 3 of rank 2. the authors study focal properties of these submanifolds and prove that they represent examples of different types of tangentially degenerate submanifolds. namely, the submanifold x ^ 3, corresponding in rp ^ 5 to a smooth line \ gamma of the projective plane c, does not have real singular points, the submanifold x ^ 3, corresponding in rp ^ 5 to a smooth line \ gamma of the projective plane c ^ 1 p ^ 2, bears two plane singular lines, and finally the submanifold x ^ 3, corresponding in rp ^ 5 to a smooth line \ gamma of the projective plane c ^ 0 p ^ 2, bears one singular line. | arxiv:math/0010192 |
this paper relates the boundary term in the chern - gauss - bonnet formula on 4 - manifolds m with the renormalized volume v, as defined in the ads / cft correspondence, for asymptotically hyperbolic einstein metrics on m. in addition, we compute and discuss the differential or variation dv of v, or equivalently the variation of the l ^ 2 norm of the weyl curvature, on the space of such einstein metrics. | arxiv:math/0011051 |
to avoid multicollinearity in regression analysis, ye and zhou ( 2013 ) proposed $ k - $ optimality criterion. by far the most popular models for modeling the response of a mixture experiment are the scheff \ ' { e } models. however, there have been no reports about constructing $ k - $ optimal designs for mixture models. the paper constructs $ k - $ optimal designs for first - order and second - order scheff \ ' { e } models. the analytical solutions for first - order and second - order scheff \ ' { e } models are obtained. a series of numerical results and examples are given to illustrate the theory. | arxiv:2210.07922 |
in this chapter we first outline some of the popular computing environments used for analysing neural data, followed by a brief discussion of ' software carpentry ', basic tools and skills from software engineering that can be of great use to computational scientists. we then introduce the concept of open - source software and explain some of its potential benefits for the academic community before giving a brief directory of some freely available open source software packages that address various aspects of the study of neural codes. while there are many commercial offerings that provide similar functionality, we concentrate here on open source packages, which in addition to being available free of charge, also have the source code available for study and modification. | arxiv:1207.5933 |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.