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the vibrational contribution $ \ mu _ { v } ( h ) $ to the dynamic magnetic permeability is calculated allowing for the spatial variation of the order parameter in the vortex cores. the behavior of calculated dependence $ \ mu _ { v } ( h ) $ is analyzed for the case when the vortices oscillate near their positions corresponding to the equilibrium vortex lattice. it is shown that taking into account the suppression of the order parameter in the vortex cores leads to appreciable difference in the behavior of $ \ mu _ { v } ( h ) $ as compared to the similar dependence obtained in the london approximation. the main reason of this difference is a change of the effective potential well in which the vibrational motion of the vortices takes place. | arxiv:cond-mat/0105368 |
we present a set of brst invariant composite operators in the $ su \ left ( 2 \ right ) \ times u \ left ( 1 \ right ) $ higgs model which exhibit an overlap with the observable scalar and vector particle states of the theory. some of these operators are non - local in the standard formulation of the higgs model, however, we show that they can be localized using the stuckelberg trick, this without changing the physical content. these operators provide thus a brst invariant resolution of the physical spectrum of the theory, thereby giving the next step in constructing a manifestly brst invariant formulation of the particle spectrum of the electroweak and standard model. | arxiv:2309.16776 |
the third data release of gaia has provided low resolution spectra for ~ 100, 000 white dwarfs ( wds ) that, together with the excellent photometry and astrometry, represent an unrivalled benchmark for the study of this population. in this work, we first built a highly - complete volume - limited sample consisting in 12, 718 wds within 100 pc from the sun. the use of vosa tool allowed us to perform an automated fitting of their spectral energy distributions to different atmospheric models. in particular, the use of spectrally derived j - pas photometry from gaia spectra led to the classification of da and non - da wds with an accuracy > 90 %, tested in already spectroscopically labelled objects. the excellent performance achieved was extended to practically the whole population of wds with effective temperatures above 5500 k. our results show that, while the a branch of the gaia wd hertzsprung - russell diagram is practically populated by da wds, the b branch is largely formed by non - das ( 65 % ). the remaining 35 % of das within the b branch implies a second peak at ~ 0. 8 mo in the da - mass distribution. additionally, the q branch and its extension to lower temperatures can be observed for both da and non - da objects due to core crystallisation. finally, we derived a detailed spectral evolution function, which confirms a slow increase of the fraction of non - das as the effective temperature decreases down to 10, 500 k, where it reaches a maximum of 36 % and then decreases for lower temperatures down to ~ 31 %. | arxiv:2211.08852 |
for handheld smartphone ar interactions, bandwidth is a critical constraint. streaming techniques have been developed to provide a seamless and high - quality user experience despite these challenges. to optimize streaming performance in smartphone - based ar, accurate prediction of the user ' s field of view is essential. this prediction allows the system to prioritize loading digital content that the user is likely to engage with, enhancing the overall interactivity and immersion of the ar experience. in this paper, we present motiontrace, a method for predicting the user ' s field of view using a smartphone ' s inertial sensor. this method continuously estimates the user ' s hand position in 3d - space to localize the phone position. we evaluated motiontrace over future hand positions at 50, 100, 200, 400, and 800ms time horizons using the large motion capture ( amass ) and smartphone - based full - body pose estimation ( pose - on - the - go ) datasets. we found that our method can estimate the future phone position of the user with an average mse between 0. 11 - 143. 62 mm across different time horizons. | arxiv:2408.01850 |
multi - soliton mode - locked laser waveforms are much sought as a complex light source for research and applications, but are difficult to manipulate effectively because of the elaborate and diverse interactions present. here we present an experimental, numerical, and theoretical study of the interaction and control of the internal dynamics of a two - soliton waveform in a mode - locked fiber laser. using the pumping current as a control agent, we demonstrate experimentally a two - orders - of - magnitude reduction in the separation of a bound soliton pair, inducing a dynamical transition between a loosely bound, phase - incoherent pair, and a tightly bound phase - locked pair. we show on the basis of a haus - model numerical simulation of the recently - proposed noise - mediated interaction theory, that the pulse separation and dynamical transition are governed by the shape of the dispersive - wave pedestals. we explain the dynamical transition by showing analytically, within a simplified theory, that the noise - mediated interaction becomes purely attractive when the pedestals energy drops below a threshold. this work demonstrates the ability to control the waveform through the interaction forces, without external intervention in the light propagation in the laser. | arxiv:2112.07136 |
, galaxy - shear and shear - shear, showing excellent agreement. | arxiv:2305.11935 |
specific choices about how to represent complex networks can have a substantial effect on the execution time required for the respective construction and analysis of those structures. in this work we report a comparison of the effects of representing complex networks statically as matrices or dynamically as spase structures. three theoretical models of complex networks are considered : two types of erdos - renyi as well as the barabasi - albert model. we investigated the effect of the different representations with respect to the construction and measurement of several topological properties ( i. e. degree, clustering coefficient, shortest path length, and betweenness centrality ). we found that different forms of representation generally have a substantial effect on the execution time, with the sparse representation frequently resulting in remarkably superior performance. | arxiv:1005.4093 |
pumping characteristics were studied of the hybrid normal - metal / superconductor single - electron transistor embedded in a high - ohmic environment. two 3 micrometer - long microstrip resistors of crox with a sum resistance r = 80kohm were placed adjacent to this hybrid device. substantial improvement of pumping and reduction of the subgap leakage were observed in the low - mhz range. at higher frequencies 0. 1 - 1ghz, a slowdown of tunneling due to the enhanced damping and electron heating negatively affected the pumping, as compared to the reference bare devices. | arxiv:0905.3402 |
broad definitions of genetic engineering include selective breeding. cloning and stem cell research, although not considered genetic engineering, are closely related and genetic engineering can be used within them. synthetic biology is an emerging discipline that takes genetic engineering a step further by introducing artificially synthesised material into an organism. plants, animals or microorganisms that have been changed through genetic engineering are termed genetically modified organisms or gmos. if genetic material from another species is added to the host, the resulting organism is called transgenic. if genetic material from the same species or a species that can naturally breed with the host is used the resulting organism is called cisgenic. if genetic engineering is used to remove genetic material from the target organism the resulting organism is termed a knockout organism. in europe genetic modification is synonymous with genetic engineering while within the united states of america and canada genetic modification can also be used to refer to more conventional breeding methods. = = history = = humans have altered the genomes of species for thousands of years through selective breeding, or artificial selection : 1 : 1 as contrasted with natural selection. more recently, mutation breeding has used exposure to chemicals or radiation to produce a high frequency of random mutations, for selective breeding purposes. genetic engineering as the direct manipulation of dna by humans outside breeding and mutations has only existed since the 1970s. the term " genetic engineering " was coined by the russian - born geneticist nikolay timofeev - ressovsky in his 1934 paper " the experimental production of mutations ", published in the british journal biological reviews. jack williamson used the term in his science fiction novel dragon ' s island, published in 1951 – one year before dna ' s role in heredity was confirmed by alfred hershey and martha chase, and two years before james watson and francis crick showed that the dna molecule has a double - helix structure – though the general concept of direct genetic manipulation was explored in rudimentary form in stanley g. weinbaum ' s 1936 science fiction story proteus island. in 1972, paul berg created the first recombinant dna molecules by combining dna from the monkey virus sv40 with that of the lambda virus. in 1973 herbert boyer and stanley cohen created the first transgenic organism by inserting antibiotic resistance genes into the plasmid of an escherichia coli bacterium. a year later rudolf jaenisch created a transgenic mouse by introducing foreign dna into its embryo, making it the world ' s first transgenic animal these achievements led to concerns in the scientific community about potential risks from genetic | https://en.wikipedia.org/wiki/Genetic_engineering |
the faulkes telescope ( ft ) project is an educational and research arm of the las cumbres observatory global telescope network ( lcogtn ). as well as producing spectacular images of galaxies, nebulae, supernovae remnants, star clusters, etc., the ft team is involved in several projects pursuing scientific goals. many of these projects also incorporate data collected and analysed by schools and amateur astronomers. | arxiv:0902.4809 |
deep neural networks ( dnn ) have demonstrated unprecedented success for medical imaging applications. however, due to the issue of limited dataset availability and the strict legal and ethical requirements for patient privacy protection, the broad applications of medical imaging classification driven by dnn with large - scale training data have been largely hindered. for example, when training the dnn from one domain ( e. g., with data only from one hospital ), the generalization capability to another domain ( e. g., data from another hospital ) could be largely lacking. in this paper, we aim to tackle this problem by developing the privacy - preserving constrained domain generalization method, aiming to improve the generalization capability under the privacy - preserving condition. in particular, we propose to improve the information aggregation process on the centralized server - side with a novel gradient alignment loss, expecting that the trained model can be better generalized to the " unseen " but related medical images. the rationale and effectiveness of our proposed method can be explained by connecting our proposed method with the maximum mean discrepancy ( mmd ) which has been widely adopted as the distribution distance measurement. experimental results on two challenging medical imaging classification tasks indicate that our method can achieve better cross - domain generalization capability compared to the state - of - the - art federated learning methods. | arxiv:2105.08511 |
we show that to account for the full spectrum of surface fluctuations from low scattering vector qd < < 1 ( classical capillary wave theory ) to high qd > 1 ( bulk - like fluctuations ), one must take account of the interface ' s bending rigidity at intermediate scattering vector qd = 1, where d is the molecular diameter. a molecular model is presented to describe the bending correction to the capillary wave model for short - ranged and long - ranged interactions between molecules. we find that the bending rigidity is negative when the gibbs equimolar surface is used to define the location of the fluctuating interface and that on approach to the critical point it vanishes proportionally to the interfacial tension. both features are in agreement with monte carlo simulations of a phase - separated colloid - polymer system. | arxiv:0812.0693 |
in this document, we present a review on an alternative nlo subtraction scheme, based on the splitting kernels of an improved parton shower that promises to facilitate the inclusion of higher order corrections into monte carlo event generators. we give expressions for the scheme for massless emitters, and point to work on the extension for massive cases. as an example, we show results for the c parameter of the process e + e - - > 3 jets at nlo which have recently been published as a verification of this scheme. we equally provide analytic expressions for integrated counterterms that have not been presented in previous work, and comment on the possibility of analytic approximations for the remaining numerical integrals | arxiv:1306.1946 |
mnn is a centrosymmetric collinear antiferromagnet belonging to the transition metal nitride family with a high neel temperature, a low anisotropy field, and a large magnetic moment per mn atom. despite several recent experimental and theoretical studies, the spin symmetry ( magnetic point group ) and magnetic domain structure of the material remain unknown. in this work, we use optical second harmonic generation ( shg ) to study the magnetic structure of thin epitaxially - grown single - crystal ( 001 ) mnn films. our work shows that spin moments in mnn are tilted away from the [ 001 ] direction and the components of the spin moments in the ( 001 ) plane are aligned along one of the two possible in - plane symmetry axes ( [ 100 ] or [ 110 ] ) resulting in a magnetic point group symmetry of 2 / m1 '. our work rules out magnetic point group symmetries 4 / mmm1 ' and mmm1 ' that have been previously discussed in the literature. four different spin domains consistent with the 2 / m1 ' magnetic point group symmetry are possible in mnn. a statistical model based on the observed variations in the polarization - dependent intensity of the second harmonic signal collected over large sample areas puts an upper bound of 0. 65 microns on the mean domain size. our results show that shg can be used to probe the magnetic order in metallic antiferromagnets. this work is expected to contribute to the recent efforts in using antiferromagnets for spintronic applications. | arxiv:2204.11741 |
this is the first paper of our systematic efforts on lepton number violating ( lnv ) hadronic decays in the effective field theory approach. these decays provide information complementary to popular nuclear neutrinoless double - $ \ beta $ ( $ 0 \ nu \ beta \ beta $ ) decay in that they can probe lnv interactions involving heavier quarks and charged leptons. we may call them hadronic $ 0 \ nu \ beta \ beta $ decays in short, though $ \ beta $ refers to all charged leptons. in this work we investigate the decays $ k ^ \ pm \ rightarrow \ pi ^ \ mp l ^ { \ pm } l ^ { \ pm } $ that arise from short - distance or contact interactions involving four quark fields and two charged lepton fields, which have canonical dimension nine ( dim - 9 ) at leading order in low energy effective field theory ( left ). we make a complete analysis on the basis of all dim - 9 operators that violate lepton number by two units, and compute their one - loop qcd renormalization effects. we match these effective interactions in left to those in chiral perturbation theory ( $ \ chi $ pt ) for pseudoscalar mesons, and determine the resulting hadronic low energy constants ( lecs ) by chiral symmetry and lattice results in the literature. the obtained decay rate is general in that all physics at and above the electroweak scale is completely parameterized by the relevant wilson coefficients in left and hadronic lecs in $ \ chi $ pt. assuming the standard model effective field theory ( smeft ) is the appropriate effective field theory between some new physics scale and the electroweak scale, we match our left results to smeft whose leading effective interactions arise from lnv dim - 7 operators. this connection to smeft simplifies significantly the interaction structures entering in the kaon decays, and we employ the current experimental bounds to set constraints on the relevant wilson coefficients in smeft. | arxiv:1909.06272 |
a preliminary result of the solar axion search experiment at the university of tokyo is presented. we searched for axions which could be produced in the solar core by exploiting the axion helioscope. the helioscope consists of a superconducting magnet with field strength of 4 tesla over 2. 3 meters. from the absence of the axion signal we set a 95 % confidence level upper limit on the axion coupling to two photons $ g _ { a \ gamma \ gamma } < 6. 0 \ times 10 ^ { - 10 } gev ^ { - 1 } $ for the axion mass $ m _ a < 0. 03 $ ev. this is the first solar axion search experiment whose sensitivity to $ g _ { a \ gamma \ gamma } $ exceeds the limit inferred from the solar age consideration. | arxiv:hep-ex/9806015 |
we investigate the prospect of constraining scalar field dark energy models using hi 21 - cm intensity mapping surveys. we consider a wide class of coupled scalar field dark energy models whose predictions about the background cosmological evolution are different from the $ \ lambda $ cdm predictions by a few percent. we find that these models can be statistically distinguished from $ \ lambda $ cdm through their imprint on the 21 - cm angular power spectrum. at the fiducial $ z = 1. 5 $, corresponding to a radio interferometric observation of the post - reionization hi 21 cm observation at frequency $ 568 \ rm mhz $, these models can infact be distinguished from the $ \ lambda $ cdm model at $ { \ rm snr } > 3 \ sigma $ level using a 10, 000 hr radio observation distributed over 40 pointings of a ska1 - mid like radio - telescope. we also show that tracker models are more likely to be ruled out in comparison with $ \ lambda $ cdm than the thawer models. future radio observations can be instrumental in obtaining tighter constraints on the parameter space of dark energy models and supplement the bounds obtained from background studies. | arxiv:1603.02087 |
we study a special teichmueller curve in the moduli space of curves of genus 3 that is intersected by infinitely many other teichmueller curves. the veech group of the underlying translation surface is sl _ 2 ( z ). all occurring teichmueller curves are induced by origamis, i. e. unramified coverings of the once punctured torus. | arxiv:math/0509195 |
by introducing a simple competition mechanism for bond insertion in random graphs, explosive percolation exhibits a sharp phase transition with rich critical phenomena. we investigate high - order connectivity in explosive percolation using an event - based ensemble, focusing on biconnected clusters, where any two sites are connected by at least two independent paths. our numerical analysis confirms that explosive percolation with different intra - cluster bond competition rules shares the same percolation threshold and universality, with biconnected clusters percolating simultaneously with simply connected clusters. however, the volume fractal dimension $ d _ { f } ' $ of biconnected clusters varies depending on the competition rules of intra - cluster bonds. the size distribution of biconnected clusters exhibits double - scaling behavior : large clusters follow the standard fisher exponent derived from the hyperscaling relation $ \ tau ' = 1 + 1 / d _ { f } ' $, while small clusters display a modified fisher exponent $ \ tau _ 0 < \ tau ' $. these findings provide insights into the intricate nature of connectivity in explosive percolation. | arxiv:2403.02789 |
hadronic tau decays belong to the processes that show a resonance - like structure in the axial vector current in the $ 1 - 2 $ gev range. this structure, often denoted as the $ a _ 1 $ meson, seems to show different properties in different processes. the process $ \ tau \ rightarrow 3 \ pi \ nu _ { \ tau } $ allows for a clean separation of weak and strong effects and a clear production mechanism. we examine how this structure can be related to interactions between the three pions that emerge in the final state. in particular we start from the interactions between all two body combinations. | arxiv:1702.05432 |
ranked set sampling ( rss ) is used as a powerful data collection technique for situations where measuring the study variable requires a costly and / or tedious process while the sampling units can be ranked easily ( e. g., osteoporosis research ). in this paper, we develop ridge and liu - type shrinkage estimators under rss data from multiple observers to handle the collinearity problem in estimating coefficients of linear regression, stochastic restricted regression and logistic regression. through extensive numerical studies, we show that shrinkage methods with the multi - observer rss result in more efficient coefficient estimates. the developed methods are finally applied to bone mineral data for analysis of bone disorder status of women aged 50 and older. | arxiv:2110.07851 |
we introduce the notion of controlled products on metric spaces as a generalization of gromov products, and construct boundaries by using controlled products, which we call the gromov boundaries. it is shown that the gromov boundary with respect to a controlled product on a proper metric space complements the space as a coarse compactification. it is also shown that there is a bijective correspondence between the set of all coarse equivalence classes of controlled products and the set of all equivalence classes of coarse compactifications. | arxiv:1810.08720 |
we demonstrate how the depleted pump of an optical parametric amplifier can be recycled for impulsive alignment of a molecular gas inside a hollow - core fiber and use such alignment for the broadening and frequency shift of the signal pulse at a center wavelength of $ \ sim 1300 $ nm. our results combine non - adiabatic molecular alignment, self - phase modulation and raman non - linearities. we demonstrate spectral shifts of up to 204 nm and a spectral broadening of more than one octave. we also report on the time delays at which broadening occurs, which do not coincide with any of the molecular rotational constants. further, we encounter that maximum frequency shifts occur when the signal and pump have perpendicular polarization instead of parallel. | arxiv:2308.05848 |
granger causality and variants of this concept allow the study of complex dynamical systems as networks constructed from multivariate time series. in this work, a large number of granger causality measures used to form causality networks from multivariate time series are assessed. these measures are in the time domain, such as model - based and information measures, the frequency domain and the phase domain. the study aims also to compare bivariate and multivariate measures, linear and nonlinear measures, as well as the use of dimension reduction in linear model - based measures and information measures. the latter is particular relevant in the study of high - dimensional time series. for the performance of the multivariate causality measures, low and high dimensional coupled dynamical systems are considered in discrete and continuous time, as well as deterministic and stochastic. the measures are evaluated and ranked according to their ability to provide causality networks that match the original coupling structure. the simulation study concludes that the granger causality measures using dimension reduction are superior and should be preferred particularly in studies involving many observed variables, such as multi - channel electroencephalograms and financial markets. | arxiv:1910.14290 |
we consider the scenario of deterministic classical information transmission between multiple senders and a single receiver, when they a priori share a multipartite quantum state - - an attempt towards building a deterministic dense coding network. specifically, we prove that in the case of two or three senders and a single receiver, generalized greenberger - horne - zeilinger ( gghz ) states are not beneficial for sending classical information deterministically beyond the classical limit, except when the shared state is the ghz state itself. on the other hand, three - and four - qubit generalized w ( gw ) states with specific parameters as well as the four - qubit dicke states can provide a quantum advantage of sending the information in deterministic dense coding. interestingly however, numerical simulations in the three - qubit scenario reveal that the percentage of states from the ghz - class that are deterministic dense codeable is higher than that of states from the w - class. | arxiv:1707.02449 |
the energy levels, generally known as the landau levels, which characterize the motion of an electron in a constant magnetic field, are those of the one - dimensional harmonic oscillator, with each level being infinitely degenerate. we show in this paper how the associated von neumann algebra of observables display a modular structure in the sense of the tomita - takesaki theory, with the algebra and its commutant referring to the two orientations of the magnetic field. a kms state can be built which in fact is the gibbs state for an ensemble of harmonic oscillators. mathematically, the modular structure is shown to arise as the natural modular structure associated to the hilbert space of all hilbert - schmidt operators. | arxiv:0906.3980 |
food classification from images is a fine - grained classification problem. manual curation of food images is cost, time and scalability prohibitive. on the other hand, web data is available freely but contains noise. in this paper, we address the problem of classifying food images with minimal data curation. we also tackle a key problems with food images from the web where they often have multiple cooccuring food types but are weakly labeled with a single label. we first demonstrate that by sequentially adding a few manually curated samples to a larger uncurated dataset from two web sources, the top - 1 classification accuracy increases from 50. 3 % to 72. 8 %. to tackle the issue of weak labels, we augment the deep model with weakly supervised learning ( wsl ) that results in an increase in performance to 76. 2 %. finally, we show some qualitative results to provide insights into the performance improvements using the proposed ideas. | arxiv:1712.08730 |
we study the reactive synthesis problem for distributed systems with an unbounded number of participants interacting with an uncontrollable environment. executions of those systems are modeled by data words, and specifications are given as first - order logic formulas from a fragment we call prefix first - order logic that implements a limited kind of order. we show that this logic has nice properties that enable us to prove decidability of the synthesis problem. | arxiv:2404.14517 |
the pairing mechanism in iron - based superconductors is the subject of ongoing debate. proximity to an antiferromagnetic phase suggests that pairing is mediated by spin fluctuations, but orbital fluctuations have also been invoked. the former typically favour a pairing state of extended s - wave symmetry with a gap that changes sign between electron and hole fermi surfaces ( s + - ), while the latter yield a standard s - wave state without sign change ( s + + ). here we show that applying pressure to kfe2as2 induces a change of pairing state. the critical temperature tc decreases with pressure initially, and then suddenly increases, above a critical pressure pc. the constancy of the hall coefficient through pc rules out a change in the fermi surface. there is compelling evidence that the pairing state below pc is d - wave, from bulk measurements at ambient pressure. above pc, the high sensitivity to disorder argues for a particular kind of s + - state. the change from d - wave to s - wave is likely to proceed via an unusual s + id state that breaks time - reversal symmetry. the proximity of two distinct pairing states found here experimentally is natural given the near degeneracy of d - wave and s + - states found theoretically. these findings make a compelling case for spin - fluctuation - mediated superconductivity in this key iron - arsenide material. | arxiv:1303.2961 |
conventional recommender systems ( rss ) face challenges in precisely capturing users ' fine - grained preferences. large language models ( llms ) have shown capabilities in commonsense reasoning and leveraging external tools that may help address these challenges. however, existing llm - based rss suffer from hallucinations, misalignment between the semantic space of items and the behavior space of users, or overly simplistic control strategies ( e. g., whether to rank or directly present existing results ). to bridge these gap, we introduce toolrec, a framework for llm - empowered recommendations via tool learning that uses llms as surrogate users, thereby guiding the recommendation process and invoking external tools to generate a recommendation list that aligns closely with users ' nuanced preferences. we formulate the recommendation process as a process aimed at exploring user interests in attribute granularity. the process factors in the nuances of the context and user preferences. the llm then invokes external tools based on a user ' s attribute instructions and probes different segments of the item pool. we consider two types of attribute - oriented tools : rank tools and retrieval tools. through the integration of llms, toolrec enables conventional recommender systems to become external tools with a natural language interface. extensive experiments verify the effectiveness of toolrec, particularly in scenarios that are rich in semantic content. | arxiv:2405.15114 |
flares in sagittarius a * are produced by hot plasmas within a few schwarzschild radii of the supermassive black hole at the galactic center. the recent detection of a correlation between the spectral index and flux during a near infrared ( nir ) flare provides a means to conduct detailed investigations of the plasma heating and radiation processes. we study the evolution of the electron distribution function under the influence of a turbulent magnetic field in a hot collisionless plasma. the magnetic field, presumably generated through instabilities in the accretion flow, can both heat the plasma via resonant wave - particle coupling and cool the electrons via radiation. the electron distribution can generally be approximated as relativistic maxwellian. to account for the observed correlation, we find that the magnetic field needs to be anti - correlated with the electron ' ' temperature ' '. nir and x - ray light curves are produced for a cooling and a heating phase. the model predicts simultaneous flare activity in the nir and x - ray bands, which can be compared with observations. these results can be applied to mhd simulations to study the radiative characteristics of collisionless plasmas, especially accretion flows in low - luminosity agns. | arxiv:astro-ph/0608232 |
based on the instantaneous bethe - salpeter equation method, we calculate the average values $ \ overline { | \ vec { q } | ^ n } \ equiv q ^ n $ and speed powers $ \ overline { | \ vec { v } | ^ n } \ equiv v ^ n $ ( $ n = 1, 2, 3, 4 $ ) of a heavy quark inside $ s $ wave and $ p $ wave heavy - light mesons, where $ \ vec { q } $ and $ \ vec { v } $ are the three dimensional momentum and velocity of the heavy quark, respectively. we obtain the kinetic energy $ \ mu ^ 2 _ { _ \ pi } = 0. 455 $ gev $ ^ 2 $ for the $ b $ meson, which is consistent with the experimental result $ 0. 464 \ pm 0. 076 $ gev $ ^ 2 $. for the $ b _ { s } $, $ d $ and $ d _ { s } $ mesons, the $ \ mu ^ 2 _ { _ \ pi } $ are $ 0. 530 $ gev $ ^ 2 $, $ 0. 317 $ gev $ ^ 2 $ and $ 0. 369 $ gev $ ^ 2 $, respectively. and $ v ^ 2 = 0. 0185 $, $ 0. 0215 $, $ 0. 121 $, and $ 0. 140 $ for $ b $, $ b _ { s } $, $ d $, and $ d _ { s } $. we obtain some relationships, for example, $ q ^ n _ { _ { 0 ^ - } } ( ms ) \ approx q ^ n _ { _ { 1 ^ - } } ( ms ) $, $ q ^ n _ { _ { 0 ^ + } } ( mp ) \ approx q ^ n _ { _ { 1 ^ { + ' } } } ( mp ^ { ' } ) > q ^ n _ { _ { 1 ^ + } } ( mp ) \ approx q ^ n _ { _ { 2 ^ + } } ( mp ) $, and $ q ^ n ( ms ) < q ^ n ( mp ) $ ( $ m = 1, 2, 3 $ ), etc. | arxiv:2405.12440 |
anisotropy in strongly correlated materials is a central parameter in determining the electronic ground state and is tuned through the local crystalline electric field. this is notably the case in the ceco $ _ { x } $ rh $ _ { 1 - x } $ in $ _ { 5 } $ system where the ground - state wave function can provide the basis for antiferromagnetism and / or unconventional superconductivity. we develop a methodology to understand the local magnetic anisotropy and experimentally investigate with neutron spectroscopy applied to antiferromagnetic ( $ t _ { n } $ = 3. 8 k ) cerhin $ _ { 5 } $ which is isostructural to $ d $ - wave superconducting ( $ t _ { c } $ = 2. 3 k ) cecoin $ _ { 5 } $. through diagonalizing the local crystal field hamiltonian with discrete tetragonal $ \ mathrm { c } _ { 4 } $ point group symmetry and coupling these states with the random phase approximation ( rpa ), we find two distinct modes polarized along the crystallographic $ c $ and $ a - b $ planes, agreeing with experiment. the anisotropy and bandwidth, underlying the energy scale of these modes, are tuneable with a magnetic field which we use experimentally to separate in energy single and multiparticle excitations thereby demonstrating the instability of excitations polarized within the crystallographic $ a - b $ plane in cerhin $ _ { 5 } $. we compare this approach to a $ s _ { eff } = { 1 \ over 2 } $ parameterizations and argue for the need to extend conventional su ( 2 ) theories of magnetic excitations to utilize the multi - level nature of the underlying crystal - field basis states constrained by the local point - group $ \ mathrm { c } _ { 4 } $ symmetry. | arxiv:2408.10158 |
master equations are typically adopted to describe the dynamics of open quantum systems. such equations are either in integro - differential or in time - local form, with the latter class more frequently adopted due to the simpler numerical methods developed to obtain the corresponding solution. here we show that any time - local master equation with positive rates in the generator, i. e. any cp - divisible quantum process, admits a microscopic model whose reduced dynamics is well described by the given equation. | arxiv:1903.06128 |
reasoning, the most important human brain operation, is charactrized by a degree fuzziness. in the present paper we construct a fuzzy model for the reasoning process giving through the calculation of the possibilities of all possible individuals ' profiles a quantitative / qualitative view of their behaviour during the above process and we use the centroid defuzzification technique for measuring the reasoning skills. we also present a number of classroom experiments illustrating our results in practice. | arxiv:1311.5355 |
we introduce a new concept, stochastic soliton lattice, as a random process generated by a finite - gap potential of the shroedinger operator. we study the basic properties of this stochastic process and consider its kdv evolution | arxiv:solv-int/9810013 |
we define a diagrammatic category that is equivalent to tilting representations for the orthogonal group. our construction works in characteristic not equal to two. we also describe the semisimplification of this category. | arxiv:2401.00704 |
chalcogenides, which refer to chalcogen anions, have attracted considerable attention in multiple fields of applications, such as optoelectronics, thermoelectrics, transparent contacts, and thin film transistors. in comparison to oxide counterparts, chalcogenides have demonstrated higher mobility and \ textit { p } - type dopability, owing to larger orbital overlaps between metal - x covalent chemical bondings and higher - energy valence bands derived by p - orbitals. despite the potential of chalcogenides, the number of successfully synthesized compounds remains relatively low compared to oxides, suggesting the presence of numerous unexplored chalcogenides with fascinating physical characteristics. in this study, we implemented a systematic high - throughput screening process combined with first - principles calculations on ternary chalcogenides using 34 crystal structure prototypes. we generated a computational material database containing over 400, 000 compounds by exploiting the ion - substitution approach at different atomic sites with elements in the periodic table. the thermodynamic stabilities of the candidates were validated using the chalcogenides included in the open quantum materials database. moreover, we trained a model based on crystal graph convolutional neural networks to predict the thermodynamic stability of novel materials. furthermore, we theoretically evaluated the electronic structures of the stable candidates using accurate hybrid functionals. a series of in - depth characteristics, including the carrier effective masses, electronic configuration, and photovoltaic conversion efficiency, was also investigated. our work provides useful guidance for further experimental research in the synthesis and characterization of such chalcogenides as promising candidates, as well as charting the stability and optoelectronic performance of ternary chalcogenides. | arxiv:2305.02634 |
we refine theorem a due to gursky \ cite { g3 }. as applications, we give some rigidity theorems on four - manifolds with postive yamabe constant. in particular, these rigidity theorems are sharp for our conditions have the additional properties of being sharp. by this we mean that we can precisely characterize the case of equality. we prove some classification theorems of four manifolds according to some conformal invariants ( see theorems 1. 3 and 1. 6 ), which generalize the conformally invariant sphere theorem of chang - gursky - yang \ cite { cgy }. | arxiv:1601.04796 |
this paper is devoted to the study of an averaging principle for fractional stochastic differential equations in rnwith l \ ' evy motion, using an integral transform method. we obtain a time - averaged equation under suitable assumptions. furthermore, we show that the solutions of averaged equation approach the solutions of the original equation. our results in this paper provide better understanding for effective approximation of fractional dynamical systems with non - gaussian l \ ' evy noise. | arxiv:2004.08430 |
the message - driven nature of actors lays a foundation for developing scalable and distributed software. while the actor itself has been thoroughly modeled, the message passing layer lacks a common definition. properties and guarantees of message exchange often shift with implementations and contexts. this adds complexity to the development process, limits portability, and removes transparency from distributed actor systems. in this work, we examine actor communication, focusing on the implementation and runtime costs of reliable and ordered delivery. both guarantees are often based on tcp for remote messaging, which mixes network transport with the semantics of messaging. however, the choice of transport may follow different constraints and is often governed by deployment. as a first step towards re - architecting actor - to - actor communication, we decouple the messaging guarantees from the transport protocol. we validate our approach by redesigning the network stack of the c + + actor framework ( caf ) so that it allows to combine an arbitrary transport protocol with additional functions for remote messaging. an evaluation quantifies the cost of composability and the impact of individual layers on the entire stack. | arxiv:1810.00401 |
institute of mechanics faculty vi – planning building environment ( planen bauen umwelt ) institute of architecture institute of civil engineering institute of applied geosciences institute of geodesy and geoinformation science institute of landscape architecture and environmental planning institute of ecology institute of sociology institute of urban and regional planning faculty vii – economics and management ( wirtschaft und management ) institute for technology and management ( itm ) institute of business administration ( ibwl ) institute of economics and law ( ivwr ) school of education ( setub ) central institute el gouna ( zentralinstitut el gouna ) = = faculty and staff = = as of 2015, 8, 455 people work at the university : 338 professors, 2, 598 postgraduate researchers, and 2, 131 personnel work in administration, the workshops, the library, and the central facilities. in addition, there are 2, 651 student assistants and 126 trainees. international student mobility is available through the erasmus programme or through the top industrial managers for europe ( time ) network. = = library = = the new common main library of technische universitat berlin and of the berlin university of the arts was opened in 2004 and holds about 2. 9 million volumes ( 2007 ). the library building was sponsored partially ( estimated 10 % of the building costs ) by volkswagen and is named officially " university library of the tu berlin and udk ( in the volkswagen building ) ". some of the former 17 libraries of technische universitat berlin and of the nearby university of the arts were merged into the new library, but several departments still retain libraries of their own. in particular, the school of ' economics and management ' maintains a library with 340, 000 volumes in the university ' s main building ( die bibliothek – wirtschaft & management / " the library " – economics and management ) and the ' department of mathematics ' maintains a library with 60, 000 volumes in the mathematics building ( mathematische fachbibliothek / " mathematics library " ). = = notable alumni and professors = = ( including those of the academies mentioned in the history section ) bruno ahrends ( 1878 – 1948 ), architect steffen ahrends ( 1907 – 1992 ), architect zora arkus - duntov ( 1909 – 1996 ), russian and american engineer and racing car driver stancho belkovski ( 1891 – 1962 ), bulgarian architect, head of higher technical school in sofia and the department of public buildings | https://en.wikipedia.org/wiki/Technische_Universität_Berlin |
if holography is an equivalence between quantum theories, one might expect it to be described by a map that is a bijective isometry between bulk and boundary hilbert spaces, preserving the hamiltonian and symmetries. holography has been believed to be a property of gravitational ( or string ) theories, but not of non - gravitational theories ; specifically marolf has argued that it originates from the gauge symmetries and constraints of gravity. these observations suggest study of the assumed holographic map as a function of the gravitational coupling $ g $. the zero coupling limit gives ordinary quantum field theory, and is therefore not necessarily expected to be holographic. this, and the structure of gravity at non - zero $ g $, raises important questions about the full map. in particular, construction of a holographic map appears to require as input a solution of the nonperturbative analog of the bulk gravitational constraints, that is, the unitary bulk evolution. moreover, examination of the candidate boundary algebra, including the boundary hamiltonian, reveals commutators that don ' t close in the usual fashion expected for a boundary theory. | arxiv:2004.07843 |
milky way ( mw ) satellites exhibit a diverse range of internal kinematics, reflecting in turn a diverse set of subhalo density profiles. these profiles include large cores and dense cusps, which any successful dark matter model must explain simultaneously. a plausible driver of such diversity is self - interactions between dark matter particles ( sidm ) if the cross section passes the threshold for the gravothermal collapse phase at the characteristic velocities of the mw satellites. in this case, some of the satellites are expected to be hosted by subhalos that are still in the classical sidm core phase, while those in the collapse phase would have cuspy inner profiles, with a sidm - driven intermediate mass black hole ( imbh ) in the centre as a consequence of the runaway collapse. we develop an analytical framework that takes into account the cosmological assembly of halos and is calibrated to previous simulations ; we then predict the timescales and mass scales ( $ m _ { \ rm bh } $ ) for the formation of imbhs in velocity - dependent sidm ( vdsidm ) models as a function of the present - day halo mass, $ m _ 0 $. finally, we estimate the region in the parameter space of the effective cross section and $ m _ 0 $ for a subclass of vdsidm models that result in a diverse mw satellite population, as well as their corresponding fraction of sidm - collapsed halos and those halos ' inferred imbh masses. we predict the latter to be in the range $ 0. 1 - 1000 ~ { \ rm m _ \ odot } $ with a $ m _ { \ rm bh } - m _ 0 $ relation that has a similar slope, but lower normalization, than the extrapolated empirical relation of super - massive black holes found in massive galaxies. | arxiv:2210.01817 |
we study metric valued fields in continuous logic, following ben yaacov ' s approach, thus working in the metric space given by the projective line. as our main result, we obtain an approximate ax - kochen - ershov principle in this framework, completely describing elementary equivalence in equicharacteristic 0 in terms of the residue field and value group. moreover, we show that, in any characteristic, the theory of metric valued difference fields does not admit a model - companion. this answers a question of ben yaacov. | arxiv:2208.10186 |
we present an agent - based model inspired by the evolutionary minority game ( emg ), albeit strongly adapted to the case of competition for limited resources in ecology. the agents in this game become able, after some time, to predict the a priori best option as a result of an evolution - driven learning process. we show that a self - segregated social structure can emerge from this process, i. e., extreme learning strategies are always favoured while intermediate learning strategies tend to die out. this result may contribute to understanding some levels of organization and cooperative behaviour in ecological and social systems. we use the ideas and results reported here to discuss an issue of current interest in ecology : the mistimings in egg laying observed for some species of bird as a consequence of their slower rate of adaptation to climate change in comparison with that shown by their prey. our model supports the hypothesis that habitat - specific constraints could explain why different populations are adapting differently to this situation, in agreement with recent experiments. | arxiv:0804.3485 |
since their invention, plastics have become ubiquitous in modern societies all around the world, and their impact on the environment has, in recent years, become nearly as well - known. plastics produced by humans have reached nearly every corner of the world, and throughout their centuries - long lifetimes, plastics continually break down into smaller and smaller particles due to the physical stresses which they are subjected to. these stresses eventually, inevitably, break these plastics down into microplastics - pieces of plastic small enough to be consumed by organisms in bodies of water throughout the globe. these microplastics can very easily bioaccumulate, and have been found everywhere from the great lakes to the bloodstreams of humans. the effects of these plastics are poorly understood, however, they have been linked to infertility, halted growth, and a host of other maladies in aquatic organisms. currently, removal of these plastics has been neglected, with no governmental action to remove them from marine environments, and this project aims to begin prototyping a solution to this issue. a significant percentage of microplastics are found at the surface of waterways, thus trawling in surface waters using an autonomously propelled net is proposed as a way to solve this seemingly intractable issue. by attaching motors and a guidance system to a manta trawl, a device currently used for collecting microorganisms, the process of collecting microplastics in open water can be automated, and thus the work of removing plastics from the environment on a large scale can begin. | arxiv:2408.02162 |
recently, large language models ( llms ) have shown surprising performance in task - specific workloads as well as general tasks with the given prompts. however, to achieve unprecedented performance, recent llms use billions to trillions of parameters, which hinder the wide adaptation of those models due to their extremely large compute and memory requirements. to resolve the issue, various model compression methods are being actively investigated. in this work, we propose sdq ( sparse decomposed quantization ) to exploit both structured sparsity and quantization to achieve both high compute and memory efficiency. from our evaluations, we observe that sdq can achieve 4x effective compute throughput with < 1 % quality drop. | arxiv:2406.13868 |
a condition to have a real spectrum for a non - hermitian hamiltonian is given. as special cases, it is shown that the condition is reduced to hermiticity and pt symmetric conditions. | arxiv:quant-ph/0702205 |
the elliptic modular j function enjoys many beautiful properties. its fourier coefficients are related to the monster group, and its cm values generate abelian extensions over imaginary quadratic fields. kaneko gave an arithmetic formula for the fourier coefficients expressed in terms of the traces of the cm values. in this article, we are concerned with analogues of kaneko ' s result for the mckay - thompson series of square - free level. | arxiv:1703.10115 |
in the presence of a minimal length physical objects cannot collapse to an infinite density, singular, matter point. in this note we consider the possible final stage of the gravitational collapse of " thick " matter layers. the energy momentum tensor we choose to model these shell - like objects is a proper modification of the source for " non - commutative geometry inspired ", regular black holes. by using higher momenta of gaussian distribution to localize matter at finite distance from the origin, we obtain new solutions of the einstein ' s equation which smoothly interpolates between minkowski geometry near the center of the shell and schwarzschild spacetime far away from the matter layer. the metric is curvature singularity free. black hole type solutions exist only for " heavy " shells, i. e. $ m \ ge m _ { e } $, where $ m _ { e } $ is the mass of the extremal configuration. we determine the hawking temperature and a modified area law taking into account the extended nature of the source. | arxiv:1110.5332 |
we study a variation of the dynamic universality class of model h in a spatial dimension of $ d = 4 - \ epsilon $, by frustrating charge diffusion and momentum density fluctuations along $ d _ t = 1 $ or $ d _ t = 2 $ dimensions, while keeping the same dynamics of model h in the other $ d _ l = d - d _ t $ dimensions. the case of $ d _ t = 2 $ describes the qcd critical point in a background magnetic field. we find that these models belong to a different dynamical universality class due to extended conservation laws compared to the model h, although the static universality class remains the same as the 3 - dimensional ising model. we compute the dynamic critical exponents of these models in first order of $ \ epsilon $ - expansion to find that $ x _ \ lambda \ approx 0. 847 \, \ epsilon $, $ x _ { \ bar \ eta } \ approx 0. 153 \, \ epsilon $, and $ z = 4 - x _ \ lambda \ approx 3. 15 $ when $ \ epsilon = 1 $ and $ d _ t = 2 $. for $ d _ t = 1 $ the results are numerically similar to the model h values : $ z \ approx 3. 08 $. | arxiv:1707.08560 |
next generation task - oriented dialog systems need to understand conversational contexts with their perceived surroundings, to effectively help users in the real - world multimodal environment. existing task - oriented dialog datasets aimed towards virtual assistance fall short and do not situate the dialog in the user ' s multimodal context. to overcome, we present a new dataset for situated and interactive multimodal conversations, simmc 2. 0, which includes 11k task - oriented user < - > assistant dialogs ( 117k utterances ) in the shopping domain, grounded in immersive and photo - realistic scenes. the dialogs are collected using a two - phase pipeline : ( 1 ) a novel multimodal dialog simulator generates simulated dialog flows, with an emphasis on diversity and richness of interactions, ( 2 ) manual paraphrasing of the generated utterances to collect diverse referring expressions. we provide an in - depth analysis of the collected dataset, and describe in detail the four main benchmark tasks we propose. our baseline model, powered by the state - of - the - art language model, shows promising results, and highlights new challenges and directions for the community to study. | arxiv:2104.08667 |
in this paper, we consider a specialist predator - prey patchy model over the closed stream network. we study the dynamics and the asymptotic profiles of positive steady states according to the mortality rate of the specialist predators, advection and diffusion rates. we verify that the specialist predators can successfully invade as long as the mortality rate is sufficiently small. on the other hand, the impacts of diffusion and advection on the asymptotic profiles of positive steady states and on the concentration of the species are given. | arxiv:2403.07520 |
coordinated motion of cell monolayers during epithelial wound healing and tissue morphogenesis involves mechanical stress generation. here we propose a model for the dynamics of epithelial expansion that couples mechanical deformations in the tissue to contractile activity and polarization in the cells. a new ingredient of our model is a feedback between local strain, polarization and contractility that naturally yields a mechanism for viscoelasticity and effective inertia in the cell monolayer. using a combination of analytical and numerical techniques, we demonstrate that our model quantitatively reproduces many experimental findings [ nat. phys. 8, 628 ( 2012 ) ], including the build - up of intercellular stresses, and the existence of traveling mechanical waves guiding the oscillatory monolayer expansion. | arxiv:1411.2258 |
static strain in complex oxide heterostructures has been extensively used to engineer electronic and magnetic properties at equilibrium. in the same spirit, deformations of the crystal lattice with light may be used to achieve functional control across hetero - interfaces dynamically. here, by exciting large amplitude infrared - active vibrations in a laalo3 substrate we induce magnetic order melting in a ndnio3 film across a hetero - interface. femtosecond resonant soft x - ray diffraction is used to determine the spatial and temporal evolution of the magnetic disordering. we observe a magnetic melt front that grows from the substrate interface into the film, at a speed that suggests electronically driven propagation. light control and ultrafast phase front propagation at hetero - interfaces may lead to new opportunities in optomagnetism, for example by driving domain wall motion to transport information across suitably designed devices. | arxiv:1505.00601 |
some model reduction techniques for multiple time - scale dynamical systems make use of the identification of low dimensional slow invariant attracting manifolds ( siam ) in order to reduce the dimensionality of the phase space by restriction to the slow flow. the focus of this work is on a proposition and discussion of a general viewpoint using differential geometric concepts for submanifolds to deal with slow invariant manifolds in an extended phase space. the motivation is a coordinate independent formulation of the manifold properties and its characterization problem treating the manifold as intrinsic geometric object. we formulate a computationally verifiable necessary condition for the slow invariant manifold graph stated in terms of a differential geometric view on the invariance property. its application to example systems is illustrated. in addition, we present some ideas and investigations concerning the search for sufficient, differential geometric conditions characterizing slow invariant manifolds based on our previously developed variational principle. | arxiv:1612.01308 |
we consider gauge field theories in $ d > 4 $ following the wilson rg approach and show that they possess the ultraviolet fixed points where the gauge coupling is dimensionless in any space - time dimension. at the fixed point the anomalous dimensions of the field and vertex operators are known exactly. these fixed points are nonperturbative and correspond to conformal invariant theories. the same phenomenon also happens in supersymmetric theories with the yukawa type interactions. | arxiv:hep-th/0209100 |
we report on the first spectrum up to 10 kev of the bright narrow - line seyfert 1 galaxy ton s 180, obtained with the imaging instruments onboard bepposax. this is the first observed source in a sample of a dozen narrow - line seyfert 1 galaxies in the bepposax core program. we also present and discuss a high quality optical spectrum taken at the 1. 5 m telescope at la silla two months before the bepposax observation. the x - ray spectrum shows a clear hardening above about 2 kev, where a power law with gamma = 2. 3 plus an iron line provide a good description of the data. this slope is significantly steeper than the typical one for classical seyfert 1 ' s and quasars. the best fit line energy is suggestive of highly ionized iron, which would support the idea that the high accretion rate is ( one of ) the fundamental parameter ( s ) characterizing the narrow line seyfert 1 phenomenon. | arxiv:astro-ph/9712182 |
we uncover new features of generalized contextuality by connecting it to the kirkwood - dirac ( kd ) quasiprobability distribution. quantum states can be represented by kd distributions, which take values in the complex unit disc. only for ` ` kd - positive ' ' states are the kd distributions joint probability distributions. a kd distribution can be measured by a series of weak and projective measurements. we design such an experiment and show that it is contextual iff the underlying state is not kd - positive. we analyze this connection with respect to mixed kd - positive states that cannot be decomposed as convex combinations of pure kd - positive states. our result is the construction of a noncontextual experiment that enables an experimenter to verify contextuality. | arxiv:2412.00199 |
titanium dioxide materials have been studied intensively and extensively due to photocatalytic applications. a long - standing open question is the energy band alignment of rutile and anatase tio2 phases, which can affect the photocatalytic process in the composite system. there are basically two contradictory viewpoints about the alignment of these two tio2 phases supported by respective experiments : 1 ) straddling type and 2 ) staggered type. in this work, our dft plus u calculations find that the perfect rutile ( 110 ) and anatase ( 101 ) surfaces have the straddling type band alignment, whereas the surfaces with defects can turn the band alignment into the staggered type. the electric dipoles induced by defects are responsible for the reversal of band alignment. thus the defects introduced during preparations and post - treatment processes of materials are probably the answer to above open question regarding the band alignment, which can be considered in real practice to tune the photocatalytic activity of materials. | arxiv:1511.02278 |
using calculations from first principles based on density functional theory we have studied the strain sensitivity of the high - field superconducting magnet a15 nb3sn. the nb3sn lattice cell was deformed in the same way as observed experimentally on multi - filamentary, technological wires subject to loads applied along their axes. the phonon dispersion curves and electronic band structures along different high - symmetry directions in the brillouin zone were calculated, at different levels of applied strain, { \ epsilon }, both on the compressive and the tensile side. starting from the calculated averaged phonon frequencies and electron - phonon coupling, the superconducting characteristic critical temperature of the material, tc, has been calculated by means of the allen - dynes modification of the mcmillan formula. as a result, the characteristic bell - shaped tc vs. { \ epsilon } curve, with a maximum at zero intrinsic strain, and with a slight asymmetry between the tensile and compressive sides, has been obtained. these first - principle calculations thus show that the strain sensitivity of nb3sn has a microscopic and intrinsic origin, originating from shifts in the nb3sn critical surface. in addition, our computations show that variations of superconducting properties of this compound are correlated to stress - induced changes in both the phononic and electronic properties. finally, the strain function describing the strain sensitivity of nb3sn has been extracted from the computed tc ( { \ epsilon } ) curve, and compared to experimental data from multi - filamentary wires. both curves show the expected bell - shaped behavior, but the strain sensitivity of the wire is enhanced with respect to the theoretical predictions of the bulk, perfectly binary and stoichiometric nb3sn. understanding the origin of this difference might open potential pathways towards the improvement of the strain tolerance in such systems. | arxiv:1210.3705 |
we study a deformation of a $ 2 $ - graded poisson algebra where the functions of the phase space variables are complemented by linear functions of parity odd velocities. the deformation is carried by a $ 2 $ - form $ b $ - field and a bivector $ \ pi $, that we consider as gauge fields of the geometric and non - geometric fluxes $ h $, $ f $, $ q $ and $ r $ arising in the context of string theory compactification. the technique used to deform the poisson brackets is widely known for the point particle interacting with a $ u ( 1 ) $ gauge field, but not in the case of non - abelian or higher spin fields. the construction is closely related to generalized geometry : with an element of the algebra that squares to zero, the graded symplectic picture is equivalent to an exact courant algebroid over the generalized tangent bundle $ e \ cong tm \ oplus t ^ { * } m $, and to its higher gauge theory. a particular idempotent graded canonical transformation is equivalent to the generalized metric. focusing on the generalized differential geometry side we construct an action functional with the ricci tensor of a connection on covectors, encoding the dynamics of a gravitational theory for a contravariant metric tensor and $ q $ and $ r $ fluxes. we also extract a connection on vector fields and determine a non - symmetric metric gravity theory involving a metric and $ h $ - flux. | arxiv:2106.09601 |
in this paper, we prove a $ p $ - hardy inequality on the discrete half - line with weights $ n ^ { \ alpha } $ for all real $ p > 1 $. building on the work of miclo for $ p = 2 $ and muckenhoupt in the continuous settings, we develop a quantitative approach for the existence of a $ p $ - hardy inequality involving two measures $ \ mu $ and $ \ nu $ on the discrete half - line. we also investigate the comparison between sharp constants in the discrete and continuous settings and explore the stability of the inequality in the discrete case. | arxiv:2501.00299 |
astronomical observations in the molecule rich 3 mm window using large reflector antennas provide a unique view of the universe. to efficiently carry out these observations gravitational and thermal deformations have to be corrected. terrestrial laser scanners have been used to measure the deformations in large reflector antennas due to gravity, but have not yet been used for measuring thermal deformations. in this work we investigate the use of a terrestrial laser scanner to measure thermal deformations on the primary reflector of the green bank telescope ( gbt ). our method involves the use of differential measurements to reduce the systematic effects of the terrestrial laser scanner. we use the active surface of the primary reflector of the gbt to validate our method and explore its limitations. we find that when using differential measurements it is possible to accurately measure deformations corresponding to different zernike polynomials down to an amplitude of 60 $ \ mu $ m. the difference between the amplitudes of known deformations and those measured are $ < 140 ~ \ mu $ m when the wind speed is $ \ lesssim2 $ m s $ ^ { - 1 } $. from these differences we estimate that it should be possible to bring the surface error of the gbt down to $ 240 \ pm6 ~ \ mu $ m. this suggests that using a commercial off - the - shelf terrestrial laser scanner it is possible to measure deformations induced by thermal gradients on a large parabolic reflector. | arxiv:2203.04133 |
an investigation of the isospin equilibration process in the reactions $ ^ { 58, 64 } $ ni + $ ^ { 58, 64 } $ ni at two bombarding energies in the fermi regime ( $ 32 \, $ mev / nucleon and $ 52 \, $ mev / nucleon ) is presented. data have been acquired during the first experimental campaign of the coupled indra - fazia apparatus in ganil. selecting from peripheral to semi - central collisions, both the neutron content of the quasiprojectile residue and that of the light ejectiles coming from the quasiprojectile evaporation have been used as probes of the dynamical process of isospin diffusion between projectile and target for the asymmetric systems. the isospin transport ratio technique has been employed. the relaxation of the initial isospin imbalance with increasing centrality has been clearly evidenced. the isospin equilibration appears stronger for the reactions at $ 32 \, $ mev / nucleon, as expected due to the longer projectile - target interaction time than at $ 52 \, $ mev / nucleon. coherent indications of isospin equilibration come from the quasiprojectile residue characteristics and from particles ascribed to the quasiprojectile decay. | arxiv:2205.10171 |
shephard groups are common generalizations of coxeter groups, artin groups, and graph products of cyclic groups. their definition is similar to that of a coxeter group, but generators may have arbitrary order rather than strictly order 2. we extend a well known result that coxeter groups are $ \ mathrm { cat } ( 0 ) $ to a class of shephard groups that have " enough " finite parabolic subgroups. we also show that in this setting, if the associated coxeter group is type ( fc ), then the shephard group acts properly and cocompactly on a $ \ mathrm { cat } ( 0 ) $ cube complex. as part of our proof of the former result, we introduce a new criteria for a complex made of $ a _ 3 $ simplices to be $ \ mathrm { cat } ( 1 ) $. | arxiv:2310.10883 |
we reduce some key calculations of compositions of morphisms between soergel bimodules ( " soergel calculus " ) to calculations in the nil hecke ring ( " schubert calculus " ). this formula has several applications in modular representation theory. | arxiv:1502.04914 |
accurately resolving the coupled momentum transfer between the liquid and solid phases of complex fluids is a fundamental problem in multiphase transport processes, such as hydraulic fracture operations. specifically we need to characterize the dependence of the normalized average fluid - particle force $ \ langle f \ rangle $ on the volume fraction of the dispersed solid phase and on the rheology of the complex fluid matrix. here we use direct numerical simulations ( dns ) to study the creeping flow ( $ re \ ll 1 $ ) of viscoelastic fluids through static random arrays of monodisperse spherical particles using a finite volume navier - stokes / cauchy momentum solver. the numerical study consists of $ n = 150 $ different systems, in which the normalized average fluid - particle force $ \ langle f \ rangle $ is obtained as a function of the volume fraction $ \ phi $ $ ( 0 < \ phi \ leq 0. 2 ) $ of the dispersed solid phase and the weissenberg number $ wi $ $ ( 0 \ leq wi \ leq 4 ) $. from these predictions a closure law $ \ langle f \ rangle ( wi, \ phi ) $ for the drag force is derived for the quasi - linear oldroyd - b viscoelastic fluid model which is, on average, within $ 5. 7 \ % $ of the dns results. additionally, a flow solver able to couple eulerian and lagrangian phases is developed, which incorporates the viscoelastic nature of the continuum phase and the closed - form drag law. two case studies were simulated using this solver, in order to assess the accuracy and robustness of the newly - developed approach for handling particle - laden viscoelastic flow configurations with $ o ( 10 ^ 5 - 10 ^ 6 ) $ rigid spheres that are representative of hydraulic fracture operations. | arxiv:2112.10834 |
using the multi - band imager mapcam onboard the osiris - rex ( origins, spectral interpretation, resource identification, and security - regolith explorer ) spacecraft, we identified 77 instances of proposed exogenic materials distributed globally on the surface of the b - type asteroid ( 101955 ) bennu. we identified materials as exogenic on the basis of an absorption near 1 um that is indicative of anhydrous silicates. the exogenic materials are spatially resolved by the telescopic camera polycam. all such materials are brighter than their surroundings, and they are expressed in a variety of morphologies : homogeneous, breccia - like, inclusion - like, and others. inclusion - like features are the most common. visible spectrophotometry was obtained for 46 of the 77 locations from mapcam images. principal component analysis indicates at least two trends : ( i ) mixing of bennu ' s average spectrum with a strong 1 - um band absorption, possibly from pyroxene - rich material, and ( ii ) mixing with a weak 1 - um band absorption. the endmember with a strong 1 - um feature is consistent with howardite - eucrite - diogenite ( hed ) meteorites, whereas the one showing a weak 1 - um feature may be consistent with heds, ordinary chondrites, or carbonaceous chondrites. the variation in the few available near - infrared reflectance spectra strongly suggests varying compositions among the exogenic materials. thus, bennu might record the remnants of multiple impacts with different compositions to its parent body, which could have happened in the very early history of the solar system. moreover, at least one of the exogenic objects is compositionally different from the exogenic materials found on the similar asteroid ( 162173 ) ryugu, and they suggest different impact tracks. | arxiv:2109.01449 |
we give a brief overview about recent developments in theories and experiments on the global and local spin polarization in heavy ion collisions. | arxiv:1704.04022 |
systems involving nematic liquid crystals subjected to magnetic fields or electric fields are modeled using the oseen - frank macroscopic continuum theory, and general criteria are developed to assess the local stability of equilibrium solutions. the criteria take into account the inhomogeneity of the electric field and the mutual influence of the electric field and the liquid - crystal director field on each other. the criteria show that formulas for the instability thresholds of electric - field freedericksz transitions cannot in all cases be obtained from those for the analogous magnetic - field transitions by simply replacing the magnetic parameters by the corresponding electric parameters, contrary to claims in standard references. this finding is consistent with [ arakelyan, karayan, chilingaryan, sov. phys. dokl., 29 ( 1984 ) 202 - 204 ]. a simple analytical test is provided to determine when an electric - field - induced instability can differ qualitatively from the analogous magnetic field - induced instability. for the systems we study, it is found that taking into account the full coupling between the electric field and the director field can either elevate or leave unchanged an instability threshold ( never lower it ), compared to the threshold provided by the magnetic - field analogy. the physical mechanism that underlies the effect of elevating an instability threshold is the added free energy associated with a first - order change in the ground - state electric field caused by a perturbation of the ground - state director field. examples are given that involve classical freedericksz transitions and also periodic instabilities. the inclusion of flexoelectric terms in the theory is studied, and it is found that these terms are not capable of altering the instability thresholds of any of the classical freedericksz transitions, consistent with known results for splay transitions. | arxiv:2005.06705 |
we present a unified numerical method to determine the shapes of multiple hele - shaw bubbles in steady motion, and in the absence of surface tension, in three planar domains : free space, the upper half - plane, and an infinite channel. our approach is based on solving the free boundary problem for the bubble boundaries using a fast and accurate boundary integral method. the main advantage of our method is that it allows for the treatment of a very high number of bubbles. the presented method is validated by recovering some existing results for steady bubbles in channels and free space. several numerical examples are presented, many of which feature configurations of bubbles that have not appeared in the literature before. | arxiv:2503.12422 |
this study addresses the pressing challenge of educational inclusion for students with special needs by proposing and developing an inclusive educational platform. integrating machine learning, natural language processing, and cross - platform interfaces, the platform features key functionalities such as speech recognition functionality to support voice commands and text generation via voice input ; real - time object recognition using the yolov5 model, adapted for educational environments ; grapheme - to - phoneme ( g2p ) conversion for text - to - speech systems using seq2seq models with attention, ensuring natural and fluent voice synthesis ; and the development of a cross - platform mobile application in flutter with on - device inference execution using tensorflow lite. the results demonstrated high accuracy, usability, and positive impact in educational scenarios, validating the proposal as an effective tool for educational inclusion. this project underscores the importance of open and accessible technologies in promoting inclusive and quality education. | arxiv:2503.15501 |
2mass j050051. 85 $ - $ 093054. 9 is the closest known low - mass helium - core white dwarf in a binary system. we used three high - band international lofar stations to perform a targeted search for a pulsar companion, reaching sensitivities of ~ 3 mjy for a 10 - ms pulsar at a dm = 1 pc $ \ cdot $ cm $ ^ { - 3 } $. no pulsed signal was detected, confidently excluding the presence of a detectable radio pulsar in the system. | arxiv:2112.02914 |
string modes in a pp - wave background are generically massive, and the worldvolume description of the branes is to be given by ` massive ' gauge theories. in this paper, we present a five dimensional super yang - mills action with the kahler - chern - simons term plus the myers term as a low energy worldvolume description of the longitudinal five branes in a maximally supersymmetric pp - wave background. we derive the action from the m - theory matrix model on the pp - wave. we utilize the previously found 4 / 32 bps solution of rotating five branes with stacks of membranes, but, to obtain the static configuration, we reformulate the matrix model in a rotating coordinate system which provides the inertial frame for the branes. expanding the matrix model around the solution, we first obtain a non - commutative field theory action naturally equipped with the full sixteen dynamical supersymmetries. in the commutative limit, we show only four supersymmetries survive, resulting in a novel five dimensional " n = 1 / 2 " theory. | arxiv:hep-th/0209219 |
direct detection, also known as direct imaging, is a method for discovering and characterizing the atmospheres of planets at intermediate and wide separations. it is the only means of obtaining spectra of non - transiting exoplanets. characterizing the atmospheres of planets in the < 5 au regime, where rv surveys have revealed an abundance of other worlds, requires a 30 - m - class aperture in combination with an advanced adaptive optics system, coronagraph, and suite of spectrometers and imagers - this concept underlies planned instruments for both tmt ( the planetary systems imager, or psi ) and the gmt ( gmagao - x ). these instruments could provide astrometry, photometry, and spectroscopy of an unprecedented sample of rocky planets, ice giants, and gas giants. for the first time habitable zone exoplanets will become accessible to direct imaging, and these instruments have the potential to detect and characterize the innermost regions of nearby m - dwarf planetary systems in reflected light. high - resolution spectroscopy will not only illuminate the physics and chemistry of exo - atmospheres, but may also probe rocky, temperate worlds for signs of life in the form of atmospheric biomarkers ( combinations of water, oxygen and other molecular species ). by completing the census of non - transiting worlds at a range of separations from their host stars, these instruments will provide the final pieces to the puzzle of planetary demographics. this whitepaper explores the science goals of direct imaging on 30 - m telescopes and the technology development needed to achieve them. | arxiv:1808.09632 |
we apply a quark combination model to study yield densities and transverse momentum ( $ p _ { t } $ ) spectra of strange ( anti - ) hadrons at mid - rapidity in central au + au collisions at $ \ sqrt { s _ { nn } } = $ 7. 7, 11. 5, 19. 6, 27, 39 and 200 gev. we show that experimental data for $ p _ { t } $ spectra of ( anti - ) hadrons in these collisions can be systematically described by the equal velocity combination of constituent quarks and antiquarks at hadronization. we obtain $ p _ { t } $ spectra of quarks and antiquarks at hadronization and study their collision energy dependence. we also reproduce the yield densities of hadrons and anti - hadrons. in particular, we demonstrate that yield ratios of anti - hadrons to hadrons $ k ^ { - } / k ^ { + } $, $ \ bar { p } / p $, $ \ bar { \ lambda } / \ lambda $, $ \ bar { \ xi } ^ { + } / \ xi ^ { - } $ and $ \ bar { \ omega } ^ { + } / \ omega ^ { - } $ simply correlate with each other and their experimental data except $ \ bar { \ omega } ^ { + } / \ omega ^ { - } $ at $ \ sqrt { s _ { nn } } = $ 7. 7 gev are systematically described by the model. these results suggest that the equal velocity combination mechanism for quarks and antiquarks at hadronization plays an important role in au + au collisions at low rhic energies ( $ \ sqrt { s _ { nn } } \ geq $ 11. 5 gev ). | arxiv:2007.14588 |
we present a detailed quantum oscillation study of the fermi surface of the recently discovered yb - based heavy fermion superconductor beta - ybalb4. we compare the data, obtained at fields from 10 to 45 tesla, to band structure calculations performed using the local density approximation. analysis of the data suggests that f - holes participate in the fermi surface up to the highest magnetic fields studied. we comment on the significance of these findings for the unconventional superconducting properties of this material. | arxiv:0811.4417 |
this paper presents photometric, astrometric, and kinematic analyses of the open clusters ngc 189, ngc 1758 and ngc 7762 based on ccd ubv photometric and gaia data release 3 ( dr3 ) data. according to membership analyses, we identified 32, 57 and 106 most probable member stars with membership probabilities $ p \ geq 0. 5 $ in ngc 189, ngc 1758 and ngc 7762, respectively. the color excesses and photometric metallicities of each cluster were determined separately using ubv two - color diagrams. the color excess $ e ( b - v ) $ is $ 0. 590 \ pm 0. 023 $ mag for ngc 189, $ 0. 310 \ pm 0. 022 $ mag for ngc 1758 and $ 0. 640 \ pm 0. 017 $ mag for ngc 7762. the photometric metallicity [ fe / h ] is $ - 0. 08 \ pm 0. 03 $ dex for both ngc 189 and ngc 1758, and $ - 0. 12 \ pm 0. 02 $ dex for ngc 7762. distance moduli and ages of the clusters were obtained by comparing parsec isochrones with the color - magnitude diagrams constructed from ubv and gaia photometric data. during this process, we kept as constant color excess and metallicity for each cluster. the estimated isochrone distance is $ 1201 \ pm 53 $ pc for ngc 189, $ 902 \ pm 33 $ pc for ngc 1758 and $ 911 \ pm 31 $ pc for ngc 7762. these are compatible with the values obtained from trigonometric parallax. ages of the clusters are $ 500 \ pm 50 $ myr, $ 650 \ pm 50 $ myr and $ 2000 \ pm 200 $ myr for ngc 189, ngc 1758 and ngc 7762, respectively. galactic orbit integration of the clusters showed that ngc 1758 completely orbits outside the solar circle, while ngc 189 and ngc 7762 enter the solar circle during their orbits. | arxiv:2304.04294 |
we determine, for the first time, the scaling dimensions of a family of fixed - charge operators stemming from the critical $ o ( n ) $ model in 4 - $ \ epsilon $ dimensions to the leading and next to leading order terms in the charge expansion but to all - orders in the coupling. we test our results to the maximum known order in perturbation theory while determining higher order terms. | arxiv:2003.13121 |
the 50 ~ kton iron calorimeter ( ical ) detector at the underground india based neutrino observatory ( ino ) will make measurements on atmospheric neutrinos. muons produced in charged current ( cc ) interactions of muon neutrinos with the iron are tracked spatially and temporally through the signals that they produce in the resistive plate chambers ~ ( rpcs ) that are interleaved with iron layers. since the rpcs will be operated in the avalanche mode the signal rise - time is $ \ sim ~ 1 ~ \ rm { nsec } $ resulting in a fast time response. while the muon track is derived from the x and y hit information of the rpcs and the layer number ( z ), the upward or downward direction is obtained by using the time information from the detector. such a capability can be examined by analysing the timing information from $ 1 ~ \ rm { m } ~ \ times ~ 1 ~ \ rm { m } $ glass rpcs, with $ 3 ~ \ rm { cm } $ wide x - and y - pick - up strips, in a $ 12 $ layer rpc stack that measures cosmic muon events. the present study looks at the pixel - wise time response of these rpcs in order to improve the relative time distribution and hence the up - down discrimination capability. after including the effect of propagation delay in the cable and pick - up panel the time resolution improves, in some cases, to $ \ leq ~ 1 ~ \ rm { nsec } $ whereas in some cases there is no significant change. these results will help in significantly improving on the extraction of the directionality of muons produced in cc interactions of $ \ nu _ { \ mu } $ and $ \ bar { \ nu } _ { \ mu } $. | arxiv:1410.5532 |
the linear polarization that is observed, together with likely changes in the orientation of the magnetic field along the line of sight and hence of the optical axes of the medium, can lead to the circular polarization that is observed in the radiation of the circumstellar sio masers. a magnetic field greater than only about 30 mg is required, in contrast to 10 - 100 g that would be implied by the zeeman interpretation. to assess quantitatively the likely changes in orientation of the magnetic field, calculations are performed with representative field configurations that are created by statistical sampling using a kolmogorov - like power spectrum. | arxiv:astro-ph/9806155 |
the role of $ sl ( 2, ir ) $ symmetry in two - dimensional gravity is investigated in the context of the extended hamiltonian formalism. using our results we clarify previous works on the subject. | arxiv:hep-th/9802065 |
markov networks are widely studied and used throughout multivariate statistics and computer science. in particular, the problem of learning the structure of markov networks from data without invoking chordality assumptions in order to retain expressiveness of the model class has been given a considerable attention in the recent literature, where numerous constraint - based or score - based methods have been introduced. here we develop a new search algorithm for the network score - optimization that has several computational advantages and scales well to high - dimensional data sets. the key observation behind the algorithm is that the neighborhood of a variable can be efficiently captured using local penalized likelihood ratio ( plr ) tests by exploiting an exponential decay of correlations across the neighborhood with an increasing graph - theoretic distance from the focus node. the candidate neighborhoods are then processed by a two - stage hill - climbing ( hc ) algorithm. our approach, termed fully as plrhc - bic $ _ { 0. 5 } $, compares favorably against the state - of - the - art methods in all our experiments spanning both low - and high - dimensional networks and a wide range of sample sizes. an efficient implementation of plrhc - bic $ _ { 0. 5 } $ is freely available from the url : https : / / github. com / jurikuronen / plrhc. | arxiv:1910.13832 |
using the standard bardeen - cooper - schrieffer ( bcs ) theory, we revise microscopic derivation of the superconductor - insulator boundary conditions for the ginzburg - landau ( gl ) model. we obtain a negative contribution to free energy in the form of surface integral. boundary conditions for the conventional superconductor have the form $ \ textbf { n } \ cdot \ nabla \ psi = \ text { const } \ psi $. these are shown to follow from considering the order parameter reflected in the boundary. the boundary conditions are also derived for more general gl models with higher - order derivatives and pair - density - wave states. it shows that the boundary states with higher critical temperature and the boundary gap enhancement, found recently in bcs theory, are also present in microscopically - derived gl theory. in the case of an applied external field, we show that the third critical magnetic - field value $ h _ { c3 } $ is higher than what follows from the de gennes boundary conditions and is also significant in type - i regime. | arxiv:2011.09519 |
we prove that the tau - function of the integrable discrete sine - gordon model apart from the " standard " bilinar identities obeys a number of " non - standard " ones. they can be combined into a bivector 3 - dimensional difference equation which is shown to contain hirota ' s difference analogue of the sine - gordon equation and both auxiliary linear problems for it. we observe that this equation is most naturally written in terms of the quantum r - matrix for the xxz spin chain and looks then like a relation of the " vertex - face correspondence " type. | arxiv:solv-int/9810003 |
conventional 2 - d scanning electron microscopy ( sem ) is commonly used to rapidly and qualitatively evaluate membrane pore structure. quantitative 2 - d analyses of pore sizes can be extracted from sem, but without information about 3 - d spatial arrangement and connectivity, which are crucial to the understanding of membrane pore structure. meanwhile, experimental 3 - d reconstruction via tomography is complex, expensive, and not easily accessible. here, we employ data - science tools to demonstrate a proof - of - principle reconstruction of the 3 - d structure of a membrane using a single 2 - d image pulled from a 3 - d tomographic data set. the reconstructed and experimental 3 - d structures were then directly compared, with important properties such as mean pore radius, mean throat radius, coordination number and tortuosity differing by less than 15 %. the developed algorithm will dramatically improve the ability of the membrane community to characterize membranes, accelerating the design and synthesis of membranes with desired structural and transport properties. | arxiv:2301.10601 |
an overview is presented of the h $ _ 2 $ quasar absorption method to search for a possible variation of the proton - - electron mass ratio $ \ mu = m _ p / m _ e $ on a cosmological time scale. details of the analysis of astronomical spectra, obtained with large 8 - - 10 m class optical telescopes, equipped with high - resolution echelle grating based spectrographs, are explained. the methods and results of the laboratory molecular spectroscopy of h $ _ 2 $, in particular the laser - based metrology studies for the determination of rest wavelengths of the lyman and werner band absorption lines, are reviewed. theoretical physics scenarios delivering a rationale for a varying $ \ mu $ will be discussed briefly, as well as alternative spectroscopic approaches to probe variation of $ \ mu $, other than the h $ _ 2 $ method. also a recent approach to detect a dependence of the proton - to - electron mass ratio on environmental conditions, such as the presence of strong gravitational fields, will be highlighted. currently some 56 h $ _ 2 $ absorption systems are known and listed. their usefulness to detect $ \ mu $ - variation is discussed, in terms of column densities and brightness of background quasar sources, along with future observational strategies. the astronomical observations of ten quasar systems analyzed so far set a constraint on a varying proton - electron mass ratio of $ | \ delta \ mu / \ mu | < 5 \ times 10 ^ { - 6 } $ ( 3 - $ \ sigma $ ), which is a null result, holding for redshifts in the range $ z = 2. 0 - 4. 2 $. this corresponds to look - back times of 10 - - 12. 4 billion years into cosmic history. attempts to interpret the results from these 10 h $ _ 2 $ absorbers in terms of a spatial variation of $ \ mu $ are currently hampered by the small sample size and their coincidental distribution in a relatively narrow band across the sky. | arxiv:1511.04476 |
singlet fission ( sf ) is a very significant photophysical phenomenon and possesses potential applications. in this work, we try to give the rather detailed theoretical investigation of the sf process in the stacked polyacene dimer by combining the high - level quantum chemistry calculations, and the quantum dynamics simulations based on the tensor train decomposition method. starting from the construction of the linear vibronic coupling model, we explore the pure electronic dynamics and the vibronic dynamics in the sf processes. the role of vibrational modes in nonadiabatic dynamics is addressed. the results show that the super - exchange mechanism mediated by the charge - transfer state is found in both pure electronic dynamics and the nonadiabatic dynamics. particularly, the vibrational modes with the frequency resonance with the adiabatic energy gap play very import roles in the sf dynamics. this work not only provides a deep and detailed understanding of the sf process, but also verifies the efficiency of the tensor train decomposition method that can serve as the reference dynamics method to explore the dynamics behaviors of complex systems. | arxiv:2308.16392 |
the adsorption and diffusion of hydrogen atoms on cu ( 001 ) are studied using first - principles calculations. by taking into account the contribution of zero - point energy ( zpe ), the originally identical barriers are shown to be different for h and d, which are respectively calculated to be ~ 158 mev and ~ 139 mev in height. using the transfer matrix method ( tmm ), we are able to calculate the accurate probability of transmission across the barriers. the crucial role of quantum tunneling is clearly demonstrated at low - temperature region. by introducing a temperature - dependent attempting frequency prefactor, the rate constants and diffusion coefficients are calculated. the results are in agreement with the experimental measurements at temperatures from ~ 50 k to 80 k. | arxiv:2306.05010 |
high dynamic range ( hdr ) photography is becoming increasingly popular and available by dslr and mobile - phone cameras. while deep neural networks ( dnn ) have greatly impacted other domains of image manipulation, their use for hdr tone - mapping is limited due to the lack of a definite notion of ground - truth solution, which is needed for producing training data. in this paper we describe a new tone - mapping approach guided by the distinct goal of producing low dynamic range ( ldr ) renditions that best reproduce the visual characteristics of native ldr images. this goal enables the use of an unpaired adversarial training based on unrelated sets of hdr and ldr images, both of which are widely available and easy to acquire. in order to achieve an effective training under this minimal requirements, we introduce the following new steps and components : ( i ) a range - normalizing pre - process which estimates and applies a different level of curve - based compression, ( ii ) a loss that preserves the input content while allowing the network to achieve its goal, and ( iii ) the use of a more concise discriminator network, designed to promote the reproduction of low - level attributes native ldr possess. evaluation of the resulting network demonstrates its ability to produce photo - realistic artifact - free tone - mapped images, and state - of - the - art performance on different image fidelity indices and visual distances. | arxiv:2111.00219 |
a $ k $ - edge - weighting of $ g $ is a mapping $ \ omega : e ( g ) \ longrightarrow \ { 1, \ ldots, k \ } $. the edge - weighting of $ g $ naturally induces a vertex - colouring $ \ sigma _ { \ omega } : v ( g ) \ longrightarrow \ mathbb { n } $ given by $ \ sigma _ { \ omega } ( v ) = \ sum _ { u \ in n _ g ( v ) } \ omega ( vu ) $ for every $ v \ in v ( g ) $. the edge - weighting $ \ omega $ is neighbour sum distinguishing if it yields a proper vertex - colouring $ \ sigma _ { \ omega } $, \ emph { i. e. }, $ \ sigma _ { \ omega } ( u ) \ neq \ sigma _ { \ omega } ( v ) $ for every edge $ uv $ of $ g $. we investigate a neighbour sum distinguishing edge - weighting with local constraints, namely, we assume that the set of edges incident to a vertex of large degree is not monochromatic. a graph is nice if it has no components isomorphic to $ k _ 2 $. we prove that every nice graph with maximum degree at most ~ 5 admits a neighbour sum distinguishing $ ( \ delta ( g ) + 2 ) $ - edge - weighting such that all the vertices of degree at least ~ 2 are incident with at least two edges of different weights. furthermore, we prove that every nice graph admits a neighbour sum distinguishing $ 7 $ - edge - weighting such that all the vertices of degree at least ~ 6 are incident with at least two edges of different weights. finally, we show that nice bipartite graphs admit a neighbour sum distinguishing $ 6 $ - edge - weighting such that all the vertices of degree at least ~ 2 are incident with at least two edges of different weights. | arxiv:2203.11521 |
given a textual description of an image, phrase grounding localizes objects in the image referred by query phrases in the description. state - of - the - art methods address the problem by ranking a set of proposals based on the relevance to each query, which are limited by the performance of independent proposal generation systems and ignore useful cues from context in the description. in this paper, we adopt a spatial regression method to break the performance limit, and introduce reinforcement learning techniques to further leverage semantic context information. we propose a novel query - guided regression network with context policy ( qrc net ) which jointly learns a proposal generation network ( pgn ), a query - guided regression network ( qrn ) and a context policy network ( cpn ). experiments show qrc net provides a significant improvement in accuracy on two popular datasets : flickr30k entities and referit game, with 14. 25 % and 17. 14 % increase over the state - of - the - arts respectively. | arxiv:1708.01676 |
aerodynamic ground effect in flapping - wing insect flight is of importance to comparative morphologies and of interest to the micro - air - vehicle ( mav ) community. recent studies, however, show apparently contradictory results of either some significant extra lift or power savings, or zero ground effect. here we present a numerical study of fruitfly sized insect takeoff with a specific focus on the significance of leg thrust and wing kinematics. flapping - wing takeoff is studied using numerical modelling and high performance computing. the aerodynamic forces are calculated using a three - dimensional navier - - stokes solver based on a pseudo - spectral method with volume penalization. it is coupled with a flight dynamics solver that accounts for the body weight, inertia and the leg thrust, while only having two degrees of freedom : the vertical and the longitudinal horizontal displacement. the natural voluntary takeoff of a fruitfly is considered as reference. the parameters of the model are then varied to explore possible effects of interaction between the flapping - wing model and the ground plane. these modified takeoffs include cases with decreased leg thrust parameter, and / or with periodic wing kinematics, constant body pitch angle. the results show that the ground effect during natural voluntary takeoff is negligible. in the modified takeoffs, when the rate of climb is slow, the difference in the aerodynamic forces due to the interaction with the ground is up to 6 %. surprisingly, depending on the kinematics, the difference is either positive or negative, in contrast to the intuition based on the helicopter theory, which suggests positive excess lift. this effect is attributed to unsteady wing - wake interactions. a similar effect is found during hovering. | arxiv:1504.04484 |
we explore observational constraints on possible deviations from newtonian gravity by means of large - scale clustering of galaxies. we measure the power spectrum and the bispectrum of sloan digital sky survey galaxies and compare the result with predictions in an empirical model of modified gravity. our model assumes an additional yukawa - like term with two parameters that characterize the amplitude and the length scale of the modified gravity. the model predictions are calculated using two methods ; the second - order perturbation theory and direct n - body simulations. these methods allow us to study non - linear evolution of large - scale structure. using the simulation results, we find that perturbation theory provides reliable estimates for the power spectrum and the bispectrum in the modified newtonian model. we also construct mock galaxy catalogues from the simulations, and derive constraints on the amplitude and the length scale of deviations from newtonian gravity. the resulting constraints from power spectrum are consistent with those obtained in our earlier work, indicating the validity of the previous empirical modeling of gravitational nonlinearity in the modified newtonian model. if linear biasing is adopted, the bispectrum of the sdss galaxies yields constraints very similar to those from the power spectrum. if we allow for the nonlinear biasing instead, we find that the ratio of the quadratic to linear biasing coefficients, b _ 2 / b _ 1, should satisfy - 0. 4 < b _ 2 / b _ 1 < 0. 3 in the modified newtonian model. | arxiv:0705.1311 |
we prove some 3 - adic congruences for binomial sums, which were conjectured by sun. | arxiv:1203.2823 |
this work sheds some light on the relationship between a distribution ' s standard deviation and its range, a topic that has been discussed extensively in the literature. while many previous studies have proposed inequalities or relationships that depend on the shape of the population distribution, the approach here is built on a family of bounded probability distributions based on skewing functions. we offer closed - form expressions for its moments and the asymptotic behavior as the support ' s semi - range tends to zero and $ \ infty $. we also establish an inequality in which the well - known popoviciu ' s one is a special case. finally, we provide an example using us dollar prices in four different currencies traded on foreign exchange markets to illustrate the results developed here. | arxiv:2303.06839 |
this paper describes a temperature sensitivity or thermal sag measurement of a geometric anti - spring based micro - electromechanical system ( mems ) gravimeter ( wee - g ). the wee - g mems gravimeter is currently fabricated on a ( 100 ) silicon wafer using standard micro - nano fabrication techniques. the thermal behavior of silicon indicates that the young ' s modulus of silicon decreases with an increase in temperature ( around 63 ppm / k ). this leads to a softening of the silicon material resulting in the proof mass ( pm ) displacing ( or sagging ) under the influence of an increasing temperature. it results in the change on the measured gravity and it is expressed as a temperature sensitivity in terms of change in gravity per degree temperature. the temperature sensitivity for the silicon based mems gravimeter is found to be 60. 14 - 64. 87 mugal / mk, 61. 76 mugal / mk and 62. 76 mugal / mk for experimental, finite element analysis ( fea ) simulation and analytical calculations respectively. it suggests that temperature sensitivity is depended on material properties used to fabricate the mems devices. in this paper the experimental measurements of thermal sag are presented, along with analytical calculations and simulations of the effect using fea ( finite element analysis ). the bespoke optical measurement system to quantify the thermal sag is also described. the results presented are an essential step towards the development of temperature insensitive mems gravimeters. | arxiv:2209.02172 |
the emergence of new wireless technologies, such as the internet of things, allows digitalizing new and diverse urban activities. thus, wireless traffic grows in volume and complexity, making prediction, investment planning, and regulation increasingly difficult. this article characterizes urban wireless traffic evolution, supporting operators to drive mobile network evolution and policymakers to increase national and local competitiveness. we propose a holistic method that widens previous research scope, including new devices and the effect of policy from multiple government levels. we provide an analytical formulation that combines existing complementary methods on traffic evolution research and diverse data sources. results for a centric area of helsinki during 2020 - 2030 indicate that daily volumes increase, albeit a surprisingly large part of the traffic continues to be generated by smartphones. machine traffic gains importance, driven by surveillance video cameras and connected cars. while camera traffic is sensitive to law enforcement policies and data regulation, car traffic is less affected by transport electrification policy. high - priority traffic remains small, even under encouraging autonomous vehicle policies. we suggest that 5g small cells might be needed around 2025, albeit the utilization of novel radio technology and additional mid - band spectrum could delay this need until 2029. we argue that mobile network operators inevitably need to cooperate in constructing a single, shared small cell network to mitigate the high deployment costs of massively deploying small cells. we also provide guidance to local and national policymakers for iot - enabled competitive gains via the mitigation of five bottlenecks. for example, local monopolies for mmwave connectivity should be facilitated on space - limited urban furniture or risk an eventual capacity crunch, slowing down digitalization. | arxiv:2310.14406 |
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