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we report our combined experimental and theoretical study of magnetoelectric properties of an antiferromagnet sr ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $, in comparison with the isostructurals ba ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $ and pb ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $. the family of compounds commonly possesses a low - symmetric magnetic unit called the square cupola, which is a source of magnetoelectric responses associated with the magnetic multipoles activated under simultaneous breaking of spatial inversion and time reversal symmetries. measuring the full magnetization curves and the magnetic - field profiles of dielectric constant for sr ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $ and comparing them with the theoretical analyses by the cluster mean - field theory, we find that the effective $ s = 1 / 2 $ spin model, which was used for the previous studies for ba ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $ and pb ( tio ) cu $ _ 4 $ ( po $ _ 4 $ ) $ _ 4 $, well explains the experimental results by tuning the model parameters. furthermore, elaborating the phase diagram of the model, we find that the square cupolas could host a variety of magnetic multipoles, i. e., monopole, toroidal moment, and quadrupole tensor, depending on the parameters that could be modulated by deformations of the magnetic square cupolas. our results not only provide a microscopic understanding of the series of the square cupola compounds, but also stimulate further exploration of the magnetoelectric behavior arising from cluster multipoles harboring in low - symmetric magnetic units.
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arxiv:1810.11929
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in this work, we focus on a special group of human body language - - the micro - gesture ( mg ), which differs from the range of ordinary illustrative gestures in that they are not intentional behaviors performed to convey information to others, but rather unintentional behaviors driven by inner feelings. this characteristic introduces two novel challenges regarding micro - gestures that are worth rethinking. the first is whether strategies designed for other action recognition are entirely applicable to micro - gestures. the second is whether micro - gestures, as supplementary data, can provide additional insights for emotional understanding. in recognizing micro - gestures, we explored various augmentation strategies that take into account the subtle spatial and brief temporal characteristics of micro - gestures, often accompanied by repetitiveness, to determine more suitable augmentation methods. considering the significance of temporal domain information for micro - gestures, we introduce a simple and efficient plug - and - play spatiotemporal balancing fusion method. we not only studied our method on the considered micro - gesture dataset but also conducted experiments on mainstream action datasets. the results show that our approach performs well in micro - gesture recognition and on other datasets, achieving state - of - the - art performance compared to previous micro - gesture recognition methods. for emotional understanding based on micro - gestures, we construct complex emotional reasoning scenarios. our evaluation, conducted with large language models, shows that micro - gestures play a significant and positive role in enhancing comprehensive emotional understanding. the scenarios we developed can be extended to other micro - gesture - based tasks such as deception detection and interviews. we confirm that our new insights contribute to advancing research in micro - gesture and emotional artificial intelligence.
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arxiv:2405.13206
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quasi - exactly solvable rational potentials with known zero - energy solutions of the schro \ " odinger equation are constructed by starting from exactly solvable potentials for which the schr \ " odinger equation admits an so ( 2, 1 ) potential algebra. for some of them, the zero - energy wave function is shown to be normalizable and to describe a bound state.
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arxiv:quant-ph/9703037
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high cost of training time caused by multi - step adversarial example generation is a major challenge in adversarial training. previous methods try to reduce the computational burden of adversarial training using single - step adversarial example generation schemes, which can effectively improve the efficiency but also introduce the problem of catastrophic overfitting, where the robust accuracy against fast gradient sign method ( fgsm ) can achieve nearby 100 \ % whereas the robust accuracy against projected gradient descent ( pgd ) suddenly drops to 0 \ % over a single epoch. to address this problem, we propose a novel fast gradient sign method with pgd regularization ( fgsmpr ) to boost the efficiency of adversarial training without catastrophic overfitting. our core idea is that single - step adversarial training can not learn robust internal representations of fgsm and pgd adversarial examples. therefore, we design a pgd regularization term to encourage similar embeddings of fgsm and pgd adversarial examples. the experiments demonstrate that our proposed method can train a robust deep network for l $ _ \ infty $ - perturbations with fgsm adversarial training and reduce the gap to multi - step adversarial training.
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arxiv:2102.03381
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the betweenness centrality of a vertex v is an important centrality measure that quantifies how many optimal paths between pairs of other vertices visit v. computing betweenness centrality in a temporal graph, in which the edge set may change over discrete timesteps, requires us to count temporal paths that are optimal with respect to some criterion. for several natural notions of optimality, including foremost or fastest temporal paths, this counting problem reduces to # temporal path, the problem of counting all temporal paths between a fixed pair of vertices ; like the problems of counting foremost and fastest temporal paths, # temporal path is # p - hard in general. motivated by the many applications of this intractable problem, we initiate a systematic study of the prameterised and approximation complexity of # temporal path. we show that the problem presumably does not admit an fpt - algorithm for the feedback vertex number of the static underlying graph, and that it is hard to approximate in general. on the positive side, we proved several exact and approximate fpt - algorithms for special cases.
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arxiv:2202.12055
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in this paper, we examine the nash equilibrium convergence properties of no - regret learning in general n - player games. for concreteness, we focus on the archetypal follow the regularized leader ( ftrl ) family of algorithms, and we consider the full spectrum of uncertainty that the players may encounter - from noisy, oracle - based feedback, to bandit, payoff - based information. in this general context, we establish a comprehensive equivalence between the stability of a nash equilibrium and its support : a nash equilibrium is stable and attracting with arbitrarily high probability if and only if it is strict ( i. e., each equilibrium strategy has a unique best response ). this equivalence extends existing continuous - time versions of the folk theorem of evolutionary game theory to a bona fide algorithmic learning setting, and it provides a clear refinement criterion for the prediction of the day - to - day behavior of no - regret learning in games
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arxiv:2101.04667
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we review major appearances of the functional expression $ \ pm \ delta \ rho ^ { 1 / 2 } / \ rho ^ { 1 / 2 } $ in the theory of diffusion - type processes and in quantum mechanically supported dynamical scenarios. attention is paid to various manifestations of " pressure " terms and their meaning ( s ) in - there.
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arxiv:1112.5962
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we study the spatially resolved excitation properties of the ionised gas in a sample of 646 galaxies using integral field spectroscopy data from sdss - iv manga. making use of baldwin - philips - terlevich diagnostic diagrams we demonstrate the ubiquitous presence of extended ( kpc scale ) low ionisation emission - line regions ( liers ) in both star forming and quiescent galaxies. in star forming galaxies lier emission can be associated with diffuse ionised gas, most evident as extra - planar emission in edge - on systems. in addition, we identify two main classes of galaxies displaying lier emission : ` central lier ' ( clier ) galaxies, where central lier emission is spatially extended, but accompanied by star formation at larger galactocentric distances, and ` extended lier ' ( elier ) galaxies, where lier emission is extended throughout the whole galaxy. in elier and clier galaxies, lier emission is associated with radially flat, low h $ \ alpha $ equivalent width of line emission ( $ < $ 3 \ aa ) and stellar population indices demonstrating the lack of young stellar populations, implying that line emission follows tightly the continuum due to the underlying old stellar population. the h $ \ alpha $ surface brightness radial profiles are always shallower than $ \ rm 1 / r ^ { 2 } $ and the line ratio [ oiii ] $ \ lambda $ 5007 / [ oii ] $ \ lambda $ 3727, 29 ( a tracer of the ionisation parameter of the gas ) shows a flat gradient. this combined evidence strongly supports the scenario in which lier emission is not due to a central point source but to diffuse stellar sources, the most likely candidates being hot, evolved ( post - asymptotic giant branch ) stars. shocks are observed to play a significant role in the ionisation of the gas only in rare merging and interacting systems.
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arxiv:1605.07189
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five planetary nebulae are known to show hydrogen - poor material near the central star. in the case of a58, this gas was ejected following a late thermal pulse similar to sakurai ' s object. in this paper i will review these five objects. one of them, iras 18333 $ - $ 2357, may not be a true pn. i will show that there is a strong case for a relation to the [ wc ] stars and their relatives, the weak emission - line stars. the surface abundances of the [ wc ] stars are explained via diffuse overshoot into the helium layer. the hydrogen - poor pne do not support this : their abundances indicate a change of abundance with depth in the helium layer. a short - lived phase of very high mass loss, the r - agb, is indicated. sakurai ' s object may be at the start of such a phase, and may evolve to very low stellar temperatures.
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arxiv:astro-ph/0105448
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we study the statistics of edges and vertices in the vicinity of a reference vertex ( origin ) within random planar quadrangulations and eulerian triangulations. exact generating functions are obtained for theses graphs with fixed numbers of edges and vertices at given geodesic distances from the origin. our analysis relies on bijections with labeled trees, in which the labels encode the information on the geodesic distance from the origin. in the case of infinitely large graphs, we give in particular explicit formulas for the probabilities that the origin have given numbers of neighboring edges and / or vertices, as well as explicit values for the corresponding moments.
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arxiv:cond-mat/0307606
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it is known that, in string sigma - model metric, the ` extreme ' fivebrane solution of d = 10 supergravity interpolates between d = 10 minkowski spacetime and a supersymmetric $ s ^ 3 $ compactification to a linear dilaton vacuum. we show here that, in { \ it fivebrane } sigma - model metric, the extreme string solution of d = 10 supergravity interpolates between minkowski spacetime and a hitherto unknown supersymmetric $ s ^ 7 $ compactification of d = 10 supergravity to a three - dimensional anti - de sitter generalization of the linear dilaton vacuum, which may be invariantly characterized in terms of conformal killing vectors. the dilaton field diverges near the string core but this divergence may be eliminated by re - interpreting the string solution as the extreme membrane solution of 11 - dimensional supergravity. we show that the latter has an analytic extension through a regular degenerate event horizon to an interior region containing a curvature singularity. we obtain analogous results for other extended object solutions of supergravity theories.
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arxiv:hep-th/9405124
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we consider the mass spectrum of the 3 $ d $ 3 - state potts model in the broken phase ( a ) near the second order ising critical point in the temperature - magnetic field plane and ( b ) near the weakly first order transition point at zero magnetic field. in the case ( a ), we compare the mass spectrum with the prediction from universality of mass ratios in the 3 $ d $ ising class ; in the case ( b ), we determine a mass ratio to be compared with the corresponding one in the spectrum of screening masses of the ( 3 + 1 ) $ d $ su ( 3 ) pure gauge theory at finite temperature in the deconfined phase near the transition. the agreement in the comparison in the case ( a ) would represent a non - trivial test of validity of the conjecture of spectrum universality. a positive answer to the comparison in the case ( b ) would suggest the possibility to extend this conjecture to weakly first order phase transitions.
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arxiv:hep-lat/0612016
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the goal of temporal alignment is to establish time correspondence between two sequences, which has many applications in a variety of areas such as speech processing, bioinformatics, computer vision, and computer graphics. in this paper, we propose a novel temporal alignment method called least - squares dynamic time warping ( lsdtw ). lsdtw finds an alignment that maximizes statistical dependency between sequences, measured by a squared - loss variant of mutual information. the benefit of this novel information - theoretic formulation is that lsdtw can align sequences with different lengths, different dimensionality, high non - linearity, and non - gaussianity in a computationally efficient manner. in addition, model parameters such as an initial alignment matrix can be systematically optimized by cross - validation. we demonstrate the usefulness of lsdtw through experiments on synthetic and real - world kinect action recognition datasets.
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arxiv:1206.4116
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we present magnetohydrodynamic simulations of a resistive accretion disk continuously launching transmagnetosonic, collimated jets. we time - evolve the full set of magnetohydrodynamic equations, but neglect radiative losses in the energetics ( radiatively inefficient ). our calculations demonstrate that a jet is self - consistently produced by the interaction of an accretion disk with an open, initially bent large - scale magnetic field. a constant fraction of heated disk material is launched in the inner equipartition disk regions, leading to the formation of a hot corona and a bright collimated, super - fastmagnetosonic jet. we illustrate the complete dynamics of the ` ` hot ' ' near steady - state outflow ( where thermal pressure $ \ simeq $ magnetic pressure ) by showing force balance, energy budget and current circuits. the evolution to this near stationary state is analyzed in terms of the temporal variation of energy fluxes controlling the energetics of the accretion disk. we find that unlike advection - dominated accretion flow, the energy released by accretion is mainly sent into the jet rather than transformed into disk enthalpy. these magnetized, radiatively inefficient accretion - ejection structures can account for under - luminous thin disks supporting bright fast collimated jets as seen in many systems displaying jets ( for instance m87 ).
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arxiv:astro-ph/0310322
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bowen ' s formula relates the hausdorff dimension of a conformal repeller to the zero of a ` pressure ' function. we present an elementary, self - contained proof which bypasses measure theory and the thermodynamic formalism to show that bowen ' s formula holds for $ c ^ 1 $ conformal repellers. we consider time - dependent conformal repellers obtained as invariant subsets for sequences of conformally expanding maps within a suitable class. we show that bowen ' s formula generalizes to such a repeller and that if the sequence is picked at random then the hausdorff dimension of the repeller almost surely agrees with its upper and lower box dimensions and is given by a natural generalization of bowen ' s formula. for a random uniformly hyperbolic julia set on the riemann sphere we show that if the family of maps and the probability law depend real - analytically on parameters then so does its almost sure hausdorff dimension.
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arxiv:math/0406114
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this paper presents the multiplicity of neutral and charged hadrons produced in 90 gev $ / c $ proton - carbon interactions from a dataset taken by the na61 / shine experiment in 2017. particle identification via de / dx was performed for the charged hadrons $ \ pi ^ \ pm $, $ k ^ \ pm $, and $ p / \ bar { p } $ ; the neutral hadrons $ k ^ 0 _ s $, $ \ lambda $, and $ \ bar { \ lambda } $ were identified via an invariant mass analysis of their decays to charged hadrons. double - differential multiplicity results as a function of laboratory momentum and polar angle are presented for each particle species ; these results provide vital constraints on the predicted neutrino beam flux for current and future long - baseline neutrino oscillation experiments.
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arxiv:2410.23098
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we study the impact of finite - size effects on the key rate of continuous - variable ( cv ) measurement - device - independent ( mdi ) quantum key distribution ( qkd ). inspired by the parameter estimation technique developed in [ rupert \ textit { et al. } phys. rev. a \ textbf { 90 }, 062310 ( 2014 ) ] ~ we adapt it to study cv - mdi - qkd and, assuming realistic experimental conditions, we analyze the impact of finite - size effects on the key rate. we find that, increasing the block - size, the performance of the protocol converges towards the ideal one, and that block - sizes between $ 10 ^ { 6 } $ and $ 10 ^ { 9 } $ data points can already provide a key rate $ \ sim10 ^ { - 2 } $ bit / use over metropolitan distances.
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arxiv:1707.04599
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a simple model for the photoproduction of kaons off protons with a lambda hyperon in the final state is presented. in a quark model, the interaction is modelled by the pair - creation of the ( anti - ) strange quarks in the final state which recombine with the three quarks of the proton to form the lambda and kaon. the calculated scattering cross sections for photon energies up to $ e _ \ gamma = 1. 9 \ ; \ mbox { gev } $ are compared to experiment. the pair - creation process is found to have a significant contribution to the total cross section.
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arxiv:hep-ph/9501342
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we investigate the portfolio selection problem against the systemic risk which is measured by covar. we first demonstrate that the systemic risk of pure stock portfolios is essentially uncontrollable due to the contagion effect and the seesaw effect. next, we prove that it is necessary and sufficient to introduce options to make the systemic risk controllable by the correlation hedging and the extreme loss hedging. in addition to systemic risk control, we show that using options can also enhance return - risk performance. then, with a reasonable approximation of the conditional distribution of optioned portfolios, we show that the portfolio optimization problem can be formulated as a second - order cone program ( socp ) that allows for efficient computation. finally, we carry out comprehensive simulations and empirical tests to illustrate the theoretical findings and the performance of our method.
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arxiv:2209.04685
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in traditional software programs, it is easy to trace program logic from variables back to input, apply assertion statements to block erroneous behavior, and compose programs together. although deep learning programs have demonstrated strong performance on novel applications, they sacrifice many of the functionalities of traditional software programs. with this as motivation, we take a modest first step towards improving deep learning programs by jointly training a generative model to constrain neural network activations to " decode " back to inputs. we call this design a decodable neural network, or decnn. doing so enables a form of compositionality in neural networks, where one can recursively compose decnn with itself to create an ensemble - like model with uncertainty. in our experiments, we demonstrate applications of this uncertainty to out - of - distribution detection, adversarial example detection, and calibration - - while matching standard neural networks in accuracy. we further explore this compositionality by combining decnn with pretrained models, where we show promising results that neural networks can be regularized from using protected features.
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arxiv:2106.00769
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the periods of the harmonic oscillations of the ion core of charged sodium clusters around the equilibrium shapes are considered. it is found that these periods are of the order of magnitude of the experimentally measured relaxation times of the plasmons, which suggests the importance of the electron - ion coupling and stresses the role played by the electron - phonon interaction in the dissipation of the plasmon energy. the relation of the process to fission is briefly discussed.
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arxiv:physics/0407086
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simulating the dynamics of complex quantum systems is a central application of quantum devices. here, we propose leveraging the power of measurements to simulate short - time quantum dynamics of physically prepared quantum states in classical post - processing using a truncated taylor series approach. while limited to short simulation times, our hybrid quantum - classical method is equipped with rigorous error bounds. it is extendable to estimate low - order taylor approximations of smooth, time - dependent functions of tractable linear combinations of measurable operators. these insights can be made use of in the context of hamiltonian learning and device verification, short - time imaginary time evolution, or the application of intractable operations to sub - universal quantum simulators in classical post - processing.
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arxiv:2412.08719
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let $ \ { x _ i ( t ), t \ ge0 \ }, i = 1, 2 $ be two standard fractional brownian motions being jointly gaussian with constant cross - correlation. in this paper we derive the exact asymptotics of the joint survival function $ $ \ mathbb { p } \ { \ sup _ { s \ in [ 0, 1 ] } x _ 1 ( s ) > u, \ \ sup _ { t \ in [ 0, 1 ] } x _ 2 ( t ) > u \ } $ $ as $ u \ rightarrow \ infty $. a novel finding of this contribution is the exponential approximation of the joint conditional first passage times of $ x _ 1, x _ 2 $. as a by - product we obtain generalizations of the borell - tis inequality and the piterbarg inequality for 2 - dimensional gaussian random fields.
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arxiv:1309.4981
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dust particles in protoplanetary disks experience various chemical reactions under different physicochemical conditions through their accretion and diffusion, which results in the radial chemical gradient of dust. we performed three - dimensional monte carlo simulations to evaluate the dust trajectories and the progress of fictitious irreversible reactions, of which kinetics is expressed by the johnson - mehl - avrami equation. the distribution of the highest temperature that each particle experiences before the degree of reaction exceeds a certain level shows the log - normal distribution, and its mode temperature was used as the effective reaction temperature. semi - analytical prediction formulas of the effective reaction temperature and its dispersion were derived by comparing a reaction timescale with a diffusive transport timescale of dust as a function of the reaction parameters and the disk parameters. the formulas reproduce the numerical results of the effective reaction temperatures and their dispersions within 5. 5 and 24 %, respectively, in a wide temperature range ( 200 - 1400 k ). we applied the formulas for the crystallization of amorphous silicate dust and its oxygen isotope exchange with the h2o vapor based on the experimentally determined kinetics. for sub - micron sized amorphous forsterite dust, the predicted effective reaction temperature for the oxygen isotope exchange was lower than that of crystallization without overlap even considering their dispersions. this suggests that the amorphous silicate dust in the protosolar disk could exchange their oxygen isotopes efficiently with the 16o - poor h2o vapor, resulting in the distinct oxygen isotope compositions from the sun.
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arxiv:2308.12571
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multivariate max - stable processes are important for both theoretical investigations and various statistical applications motivated by the fact that these are limiting processes, for instance of stationary multivariate regularly varying time series, [ 1 ]. in this contribution we explore the relation between homogeneous functionals and multivariate max - stable processes and discuss the connections between multivariate max - stable process and zonoid / max - zonoid equivalence. we illustrate our results considering brown - resnick and smith processes.
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arxiv:2102.06736
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recognising new or unusual features of an environment is an ability which is potentially very useful to a robot. this paper demonstrates an algorithm which achieves this task by learning an internal representation of ` normality ' from sonar scans taken as a robot explores the environment. this model of the environment is used to evaluate the novelty of each sonar scan presented to it with relation to the model. stimuli which have not been seen before, and therefore have more novelty, are highlighted by the filter. the filter has the ability to forget about features which have been learned, so that stimuli which are seen only rarely recover their response over time. a number of robot experiments are presented which demonstrate the operation of the filter.
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arxiv:cs/0006006
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in this work, we investigate the capacity of generative adversarial networks ( gans ) in interpolating and extrapolating facies proportions in a geological dataset. the new generated realizations with unrepresented ( aka. missing ) proportions are assumed to belong to the same original data distribution. specifically, we design a conditional gans model that can drive the generated facies toward new proportions not found in the training set. the presented study includes an investigation of various training settings and model architectures. in addition, we devised new conditioning routines for an improved generation of the missing samples. the presented numerical experiments on images of binary and multiple facies showed good geological consistency as well as strong correlation with the target conditions.
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arxiv:2203.09639
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the psu ( 2, 2 | 4 ) integrable super spin chain underlying the ads / cft correspondence has integrable boundary states which describe set - ups where k d3 - branes get dissolved in a probe d5 - brane. overlaps between bethe eigenstates and these boundary states encode the one - point functions of conformal operators and are expressed in terms of the superdeterminant of the gaudin matrix that in turn depends on the dynkin diagram of the symmetry algebra. the different possible dynkin diagrams of super lie algebras are related via fermionic dualities and we determine how overlap formulae transform under these dualities. as an application we show how to consistently move between overlap formulae obtained for k = 1 from different dynkin diagrams.
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arxiv:2011.12192
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this paper presents a novel metric to evaluate the robustness of deep learning based semantic segmentation approaches for crop row detection under different field conditions encountered by a field robot. a dataset with ten main categories encountered under various field conditions was used for testing. the effect on these conditions on the angular accuracy of crop row detection was compared. a deep convolutional encoder decoder network is implemented to predict crop row masks using rgb input images. the predicted mask is then sent to a post processing algorithm to extract the crop rows. the deep learning model was found to be robust against shadows and growth stages of the crop while the performance was reduced under direct sunlight, increasing weed density, tramlines and discontinuities in crop rows when evaluated with the novel metric.
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arxiv:2109.08247
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we report an observation of room temperature magnetodielectric ( rtmd ) effect in mn doped lagao3. results of frequency dependent magnetoresistance ( fdmr ) measurements discards the possibility of any magnetoresistive contribution in the observed md effect. the intrinsic nature of md coupling has been validated / evidenced by means of magnetic field dependent raman spectroscopy and explained in terms of modified volume strain governed by magnetic field induced rerotation of spin coupled mn - orbitals. ultimately, present rtmd effect is attributed to magneto - compression / magnetostriction associated with spin - phonon coupling as evidenced in the form of magnetic field induced hardening of symmetric stretching ( ss ) mno6 octahedral raman modes. presently studied mn doped lagao3 can be a candidate for magnetodielectric applications.
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arxiv:1705.00184
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an open challenge problem at the forefront of modern neuroscience is to obtain a comprehensive mapping of the neural pathways that underlie human brain function ; an enhanced understanding of the wiring diagram of the brain promises to lead to new breakthroughs in diagnosing and treating neurological disorders. inferring brain structure from image data, such as that obtained via electron microscopy ( em ), entails solving the problem of identifying biological structures in large data volumes. synapses, which are a key communication structure in the brain, are particularly difficult to detect due to their small size and limited contrast. prior work in automated synapse detection has relied upon time - intensive biological preparations ( post - staining, isotropic slice thicknesses ) in order to simplify the problem. this paper presents vesicle, the first known approach designed for mammalian synapse detection in anisotropic, non - post - stained data. our methods explicitly leverage biological context, and the results exceed existing synapse detection methods in terms of accuracy and scalability. we provide two different approaches - one a deep learning classifier ( vesicle - cnn ) and one a lightweight random forest approach ( vesicle - rf ) to offer alternatives in the performance - scalability space. addressing this synapse detection challenge enables the analysis of high - throughput imaging data soon expected to reach petabytes of data, and provide tools for more rapid estimation of brain - graphs. finally, to facilitate community efforts, we developed tools for large - scale object detection, and demonstrated this framework to find $ \ approx $ 50, 000 synapses in 60, 000 $ \ mu m ^ 3 $ ( 220 gb on disk ) of electron microscopy data.
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arxiv:1403.3724
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the extremely low mass white dwarfs ( elm wds ) and pre - elm wds are helium core white dwarfs with mass $ < \ sim 0. 3m _ { \ odot } $. evolution simulations show that a lower mass limit for elm wds exists at $ \ approx0. 14m _ { \ odot } $ and no one is proposed by observation to be less massive than that. here we report the discovery of a binary system, lamost j224040. 77 - 020732. 8 ( j2240 in short ), which consists of a very low mass hot star and a compact companion. multi - epoch spectroscopy shows an orbital period $ p _ { orb } = $ 0. 219658 $ \ pm0. 000002 $ days and a radial velocity semi - amplitude $ k1 = 318. 5 \ pm3. 3km / s $, which gives the mass function of 0. 74 $ m _ { \ odot } $, indicating the companion is a compact star. the f - type low resolution spectra illustrate no emission features, and the temperature ( $ \ sim 7400k $ ) is consistent with that from spectral energy distribution fitting and multi - color light curve solution. the optical light curves, in ztf g, r and i bands and catalina v band, show ellipsoidal variability with amplitudes $ \ sim30 \ % $, suggesting that the visible component is heavily tidally distorted. combining the distance from gaia survey, the ztf light curves are modeled with wilson - devinney code and the result shows that the mass of the visible component is $ m1 = 0. 085 ^ { + 0. 036 } _ { - 0. 024 } m _ { \ odot } $, and the mass of the invisible component is $ m2 = 0. 98 ^ { + 0. 16 } _ { - 0. 09 } m _ { \ odot } $. the radius of the visible component is $ r1 = 0. 29 ^ { + 0. 04 } _ { - 0. 03 } r _ { \ odot } $. the inclination angle is approximately between 60 $ ^ { \ circ } $ and 90 $ ^ { \ circ } $. the observations indicate the system is most likely a pre - elm wd + wd / ns binary, and the mass of pre - elm is possibly lower than the $ 0. 14m _ { \ odot } $ theoretical limit.
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arxiv:2209.10386
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we prove global gradient estimates for parabolic $ p $ - laplace type equations with measure data, whose model is $ $ u _ t - \ textrm { div } \ left ( | du | ^ { p - 2 } du \ right ) = \ mu \ quad \ textrm { in } \ \ omega \ times ( 0, t ) \ subset \ mathbb { r } ^ n \ times \ mathbb { r }, $ $ where $ \ mu $ is a signed radon measure with finite total mass. we consider the singular case $ $ \ frac { 2n } { n + 1 } < p \ le 2 - \ frac { 1 } { n + 1 } $ $ and give possibly minimal conditions on the nonlinearity and the boundary of $ \ omega $, which guarantee the regularity results for such measure data problems.
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arxiv:2004.03889
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real world systems typically feature a variety of different dependency types and topologies that complicate model selection for probabilistic graphical models. we introduce the ensemble - of - forests model, a generalization of the ensemble - of - trees model. our model enables structure learning of markov random fields ( mrf ) with multiple connected components and arbitrary potentials. we present two approximate inference techniques for this model and demonstrate their performance on synthetic data. our results suggest that the ensemble - of - forests approach can accurately recover sparse, possibly disconnected mrf topologies, even in presence of non - gaussian dependencies and / or low sample size. we applied the ensemble - of - forests model to learn the structure of perturbed signaling networks of immune cells and found that these frequently exhibit non - gaussian dependencies with disconnected mrf topologies. in summary, we expect that the ensemble - of - forests model will enable mrf structure learning in other high dimensional real world settings that are governed by non - trivial dependencies.
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arxiv:1312.4710
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all instances of the semidirect key exchange protocol, a generalisation of the famous diffie - hellman key exchange protocol, satisfy the so - called " telescoping equality " ; in some cases, this equality has been used to construct an attack. in this report we present computational evidence suggesting that an instance of the scheme called ` mobs ' is an example of a scheme where the telescoping equality has too many solutions to be a practically viable means to conduct an attack.
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arxiv:2111.05806
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the principal goal of the nasa terrestrial planet finder ( tpf ) and esa darwin mission concepts is to directly detect and characterize extrasolar terrestrial ( earth - sized ) planets. this first generation of instruments is expected to provide disk - averaged spectra with modest spectral resolution and signal - to - noise. here we use a spatially and spectrally resolved model of the planet mars to study the detectability of a planet ' s surface and atmospheric properties from disk - averaged spectra as a function of spectral resolution and wavelength range, for both the proposed visible coronograph ( tpf - c ) and mid - infrared interferometer ( tpf - i / darwin ) architectures. at the core of our model is a spectrum - resolving ( line - by - line ) atmospheric / surface radiative transfer model which uses observational data as input to generate a database of spatially - resolved synthetic spectra for a range of illumination conditions ( phase angles ) and viewing geometries. results presented here include disk averaged synthetic spectra, light - curves and the spectral variability at visible + mid - ir wavelengths for mars as a function of viewing angle, illumination, season. we also considered the appearance of an increasingly frozen mars and simulated its detection versus real mars with tpf - c and tpf - i as a function of spectral resolving power, signal - to - noise, integration time.
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arxiv:astro-ph/0408372
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we present a theoretical study of the statics and dynamics of a partially wetting liquid droplet, of equilibrium contact angle $ \ theta _ { \ rm e } $, confined in a solid wedge geometry of opening angle $ \ beta $. we focus on a mostly non - wetting regime, given by the condition $ \ theta _ { \ rm e } - \ beta > 90 ^ \ circ $, where the droplet forms a liquid barrel - - a closed shape of positive mean curvature. using a quasi - equilibrium assumption for the shape of the liquid - gas interface, we compute the surface energy landscapes experienced by the liquid upon translations along the symmetry plane of the wedge. close to equilibrium, our model is in good agreement with numerical calculations of the surface energy minimisation subject to a constrained position of the centre of mass of the liquid. beyond the statics, we put forward a lagrangian description for the droplet dynamics. we focus on the the over - damped limit, where the driving capillary force is balanced by the frictional forces arising from the bulk hydrodynamics, the corner flow near the contact lines and the contact line friction. our results provide a theoretical framework to describe the motion of partially wetting liquids in confinement, and can be used to gain further understanding on the relative importance of dissipative processes that span from microscopic to macroscopic length scales.
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arxiv:1702.06076
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we perform the exact numerical diagonalization of the hamiltonians that describe both degenerate and nondegenerate parametric amplifiers, by exploiting the conservation laws pertaining each device. we clarify the conditions under which the parametric approximation holds, showing that the most relevant requirement is the coherence of the pump after the interaction, rather than its undepletion.
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arxiv:quant-ph/9902013
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the symplectic cone of a closed oriented 4 - manifold is the set of cohomology classes represented by symplectic forms. a well - known conjecture describes this cone for every minimal kaehler surface. we consider the case of the elliptic surfaces e ( n ) and focus on a slightly weaker conjecture for the closure of the symplectic cone. we prove this conjecture in the case of the spin surfaces e ( 2m ) using inflation and the action of self - diffeomorphisms of the elliptic surface. an additional obstruction appears in the non - spin case.
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arxiv:1210.1135
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pulsar winds shocked in the ambient medium produce spectacular nebulae observable from the radio through gamma - rays. the shape and the spectrum of a pulsar wind nebula ( pwn ) depend on the angular distribution, magnetization and energy spectrum of the wind streaming from the pulsar magnetosphere, as well as on the pulsar velocity and the properties of the ambient medium. the advent of chandra, with its unprecedented angular resolution and high sensitivity, has allowed us not only to detect many new pwne, but also study their spatial and spectral structure and dynamics, which has significantly advanced our understanding of these objects. here we overview recent observational results on pwne, with emphasis on chandra observations.
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arxiv:0801.2602
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during the normal operation of a power system all the voltages and currents are sinusoids with a frequency of 60 hz in america and parts of asia, or of 50hz in the rest of the world. forcing all the currents and voltages to be sinusoids with the right frequency is one of the most important problems in power systems. this problem is known as the transient stability problem in the power systems literature. the classical models used to study transient stability are based on several implicit assumptions that are violated when transients occur. one such assumption is the use of phasors to study transients. while phasors require sinusoidal waveforms to be well defined, there is no guarantee that waveforms will remain sinusoidal during transients. in this paper, we use energy - based models derived from first principles that are not subject to hard - to - justify classical assumptions. in addition to eliminate assumptions that are known not to hold during transient stages, we derive intuitive conditions ensuring the transient stability of power systems with lossy transmission lines. furthermore, the conditions for transient stability are compositional in the sense that one infers transient stability of a large power system by checking simple conditions for individual generators.
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arxiv:1309.5422
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in the present note we study determinantal arrangements constructed with use of the $ 3 $ - minors of a $ 3 \ times 5 $ generic matrix of indeterminates. in particular, we show that certain naturally constructed hypersurface arrangements in $ \ mathbb { p } ^ { 14 } _ { \ mathbb { c } } $ are free.
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arxiv:2201.01049
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although face recognition systems have seen a massive performance enhancement in recent years, they are still targeted by threats such as presentation attacks, leading to the need for generalizable presentation attack detection ( pad ) algorithms. current pad solutions suffer from two main problems : low generalization to unknown cenarios and large training data requirements. foundation models ( fm ) are pre - trained on extensive datasets, achieving remarkable results when generalizing to unseen domains and allowing for efficient task - specific adaption even when little training data are available. in this work, we recognize the potential of fms to address common pad problems and tackle the pad task with an adapted fm for the first time. the fm under consideration is adapted with lora weights while simultaneously training a classification header. the resultant architecture, foundpad, is highly generalizable to unseen domains, achieving competitive results in several settings under different data availability scenarios and even when using synthetic training data. to encourage reproducibility and facilitate further research in pad, we publicly release the implementation of foundpad at https : / / github. com / gurayozgur / foundpad.
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arxiv:2501.02892
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the discrete tori are graph analogues of the real tori, which are defined by the cayley graphs of a finite product of finite cyclic groups. in this paper, using the theory of the heat kernel on the discrete tori established by chinta, jorgenson and karlsson, we derive an explicit prime geodesic theorem for the discrete tori, which is not an asymptotic formula. to describe the formula, we need generalizations of the classical jacobi polynomials, which are defined by the lauricella multivariable hypergeometric function of type c.
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arxiv:1603.01949
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the electrostatic cumulation of current density in relativistic vacuum diodes with ring - type cathodes is described theoretically and confirmed experimentally. the distinctive feature of the suggested cumulation mechanism is a very low energy spread of electrons. as a result of electrostatic cumulation, a thin relativistic electron beam with a current density of 1 ka / mm $ ^ 2 $ can be formed. this quantity exceeds typical current density values in high - current cherenkov sources by an order of magnitude. such a beam can be used as an active medium in high - power terahertz sources.
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arxiv:1811.12526
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we show how the excursion set moving barrier model for halo abundances may be generalized to the local non - gaussian f _ { nl } model. our estimate assumes that the distribution of step sizes depends on f _ { nl }, but that they are otherwise uncorrelated. our analysis is consistent with previous results for the case of a constant barrier, and highlights some implicit assumptions. it also clarifies the basis of an approximate analytic solution to the moving barrier problem in the gaussian case, and shows how it might be improved.
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arxiv:0905.1702
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the concept of transportation demand management ( tdm ) upholds the development of sustainable mobility through the triumph of optimally balanced transport modal share in cities. the modal split management directly reflects on tdm of each transport subsystem, including parking. in developing countries, the policy - makers have largely focused on supply - side measures, yet demand - side measures have remained unaddressed in policy implications. ample literature is available presenting responses of tdm strategies, but most studies account mode choice and parking choice behaviour separately rather than considering trade - offs between them. failing to do so may lead to biased model estimates and impropriety in policy implications. this paper seeks to fill this gap by admitting parking choice as an endogenous decision within the model of mode choice behaviour. this study integrates attitudinal factors and built - environment variables in addition to parking and travel attributes for developing comprehensive estimation results. a mixed logit model with random coefficients is estimated using hierarchical bayes approach based on the markov chain monte carlo simulation method. the results reveal significant influence of mode / parking specific attitudes on commuters choice behaviour in addition to the built - environment factors and mode / parking related attributes. it is identified that considerable shift is occurring between parking - types in preference to switching travel mode with hypothetical changes in parking attributes. besides, study investigates the heterogeneity in the willingness - to - pay through a follow - up regression model, which provides important insights for identifying possible sources of this heterogeneity among respondents. the study provides remarkable results which may be beneficial to planning authorities for improving tdm strategies especially in developing countries.
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arxiv:2109.01045
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the classical kepler problem, as well as its quantum mechanical version, the hydrogen atom, enjoy a well - known hidden symmetry, the conservation of the laplace - runge - lenz vector, which makes these problems superintegrable. is there a relativistic quantum field theory extension that preserves this symmetry? in this letter we show that the answer is positive : in the non - relativistic limit, we identify the dual conformal symmetry of planar $ \ mathcal { n } = 4 $ super yang - mills with the well - known symmetries of the hydrogen atom. we point out that the dual conformal symmetry offers a novel way to compute the spectrum of bound states of massive $ w $ bosons in the theory. we perform nontrivial tests of this setup at weak and strong coupling, and comment on the possible extension to arbitrary values of the coupling.
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arxiv:1408.0296
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we introduce and study a general version of the fractional online knapsack problem with multiple knapsacks, heterogeneous constraints on which items can be assigned to which knapsack, and rate - limiting constraints on the assignment of items to knapsacks. this problem generalizes variations of the knapsack problem and of the one - way trading problem that have previously been treated separately, and additionally finds application to the real - time control of electric vehicle ( ev ) charging. we introduce a new algorithm that achieves a competitive ratio within an additive factor of one of the best achievable competitive ratios for the general problem and matches or improves upon the best - known competitive ratio for special cases in the knapsack and one - way trading literatures. moreover, our analysis provides a novel approach to online algorithm design based on an instance - dependent primal - dual analysis that connects the identification of worst - case instances to the design of algorithms. finally, we illustrate the proposed algorithm via trace - based experiments of ev charging.
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arxiv:2010.00412
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we investigate numerical solution of the dokshitzer - gribov - lipatov - altarelli - parisi ( dglap ) q ^ 2 evolution equation for the transversity distribution delta _ t q or the structure function h _ 1. the leading - order ( lo ) and next - to - leading - order ( nlo ) evolution equations are studied. the renormalization scheme is ms or overline { ms } in the nlo case. dividing the variables x and q ^ 2 into small steps, we solve the integrodifferential equations by the euler method in the variable q ^ 2 and by the simpson method in the variable x. numerical results indicate that accuracy is better than 1 % in the region 10 ^ { - 5 } < x < 0. 8 if more than fifty q ^ 2 steps and more than five hundred x steps are taken. we provide a fortran program for the q ^ 2 evolution and devolution of the transversity distribution delta _ t q or h _ 1. using the program, we show the lo and nlo evolution results of the valence - quark distribution delta _ t u _ v + delta _ t d _ v, the singlet distribution sum _ i ( delta _ t q _ i + delta _ t qbar _ i ), and the flavor asymmetric distribution delta _ t ubar - delta _ t dbar. they are also compared with the longitudinal evolution results.
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arxiv:hep-ph/9712410
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generative adversarial networks ( gans ) have proven to be a powerful tool in generating artistic images, capable of mimicking the styles of renowned painters, such as claude monet. this paper introduces a tiered gan model to progressively refine image quality through a multi - stage process, enhancing the generated images at each step. the model transforms random noise into detailed artistic representations, addressing common challenges such as instability in training, mode collapse, and output quality. this approach combines downsampling and convolutional techniques, enabling the generation of high - quality monet - style artwork while optimizing computational efficiency. experimental results demonstrate the architecture ' s ability to produce foundational artistic structures, though further refinements are necessary for achieving higher levels of realism and fidelity to monet ' s style. future work focuses on improving training methodologies and model complexity to bridge the gap between generated and true artistic images. additionally, the limitations of traditional gans in artistic generation are analyzed, and strategies to overcome these shortcomings are proposed.
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arxiv:2412.05724
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in this paper, we introduce a novel concept called the graph geometric control condition ( ggcc ). it turns out to be a simple, geometric rewriting of many of the frameworks in which the controllability of pdes on graphs has been studied. we prove that ( ggcc ) is a necessary and sufficient condition for the exact controllability of the wave equation on metric graphs with internal controls and dirichlet boundary conditions. we then investigate the internal exact controllability of the wave equation with mixed boundary conditions and the one of the schr \ " odinger equation, as well as the internal null - controllability of the heat equation. we show that ( ggcc ) provides a sufficient condition for the controllability of these equations and we provide explicit examples proving that ( ggcc ) is not necessary in these cases.
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arxiv:2503.18864
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in cooperative multi - agent robotic systems, coordination is necessary in order to complete a given task. important examples include search and rescue, operations in hazardous environments, and environmental monitoring. coordination, in turn, requires simultaneous satisfaction of safety critical constraints, in the form of state and input constraints, and a connectivity constraint, in order to ensure that at every time instant there exists a communication path between every pair of agents in the network. in this work, we present a model predictive controller that tackles the problem of performing multi - agent coordination while simultaneously satisfying safety critical and connectivity constraints. the former is formulated in the form of state and input constraints and the latter as a constraint on the second smallest eigenvalue of the associated communication graph laplacian matrix, also known as fiedler eigenvalue, which enforces the connectivity of the communication network. we propose a sequential quadratic programming formulation to solve the associated optimization problem that is amenable to distributed optimization, making the proposed solution suitable for control of multi - agent robotics systems relying on local computation. finally, the effectiveness of the algorithm is highlighted with a numerical simulation.
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arxiv:2303.06957
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trojan asteroids are minor planets that share the orbit of a planet about the sun and librate around the l4 or l5 lagrangian points of stability. they are important because they carry information on early solar system formation, when collisions between bodies were more frequent. discovery and study of terrestrial planet trojans will help constrain models for the distribution of bodies and interactions in the inner solar system. we present models that constrain optimal search areas, and strategies for survey telescopes to maximize the probability of detecting inner planet trojans. we also consider implications for detection with respect to the gaia satellite, and limitations of gaia ' s observing geometry.
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arxiv:1111.2427
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we demonstrate that next generation high - energy neutrino telescopes may reveal the existence of interactions induced by standard model electroweak instantons. the energy spectrum, the angular distribution, and the quark and lepton multiplicity of events in the detector each provide signatures which can indicate the presence of these interactions. high - energy neutrino telescopes may be capable of searching for signals at energies far beyond the reach of the next generation colliders.
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arxiv:hep-ph/0307120
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in this work we introduce a thermal magnetotorsional effect ( tme ) as a novel topological response in magnetic weyl semimetals. we predict that magnetization gradients perpendicular to the weyl node separation give rise to temperature gradients depending only on the local positions of the weyl nodes. the tme is a consequence of magnetization - induced effective torsional spacetime geometry and the finite temperature nieh - yan anomaly. similarly to anomalous hall effect and chiral anomaly, the tme has a universal material - independent form. we predict that the tme can be observed in magnetic weyl semimetal eucd $ _ 2 $ as $ _ 2 $.
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arxiv:1912.07732
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materials science in science fiction is the study of how materials science is portrayed in works of science fiction. the accuracy of the materials science portrayed spans a wide range – sometimes it is an extrapolation of existing technology, sometimes it is a physically realistic portrayal of a far - out technology, and sometimes it is simply a plot device that looks scientific, but has no basis in science. examples are : realistic : in 1944, the science fiction story " deadline " by cleve cartmill depicted the atomic bomb. the properties of various radioactive isotopes are critical to the proposed device, and the plot. this technology was real, unknown to the author. extrapolation : in the 1979 novel the fountains of paradise, arthur c. clarke wrote about space elevators – basically long cables extending from the earth ' s surface to geosynchronous orbit. these require a material with enormous tensile strength and light weight. carbon nanotubes are strong enough in theory, so the idea is plausible ; while one cannot be built today, it violates no physical principles. plot device : an example of an unsupported plot device is scrith, the material used to construct ringworld, in the novels by larry niven. scrith has unreasonable strength, and is unsupported by known physics, but needed for the plot. critical analysis of materials science in science fiction falls into the same general categories. the predictive aspects are emphasized, for example, in the motto of the georgia tech ' s department of materials science and engineering – materials scientists lead the way in turning yesterday ' s science fiction into tomorrow ' s reality. this is also the theme of many technical articles, such as material by design : future science or science fiction?, found in ieee spectrum, the flagship magazine of the institute of electrical and electronics engineers. on the other hand, there is criticism of the unrealistic materials science used in science fiction. in the professional materials science journal jom, for example, there are articles such as the ( mostly improbable ) materials science and engineering of the star wars universe and personification : the materials science and engineering of humanoid robots. = = examples = = in many cases, the materials science aspect of a fictional work was interesting enough that someone other than the author has remarked on it. here are some examples, and their relationship to real world materials science usage, if any. = = see also = = science in science fiction hypothetical types of biochemistry. most of these potential types of biochemistry have been used in science fiction. uno
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https://en.wikipedia.org/wiki/Materials_science_in_science_fiction
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we initiate the lisa template databank for stochastic gravitational wave backgrounds sourced by cosmic strings. we include two templates, an analytical template, which enables more flexible searches, and a numerical template derived directly from large nambu - goto simulations of string networks. using searches based on these templates, we forecast the parameter space within the reach of the experiment and the precision with which their parameters will be reconstructed, provided a signal is observed. the reconstruction permits probing the hubble expansion and new relativistic dof in the early universe. we quantify the impact that astrophysical foregrounds can have on these searches. finally, we discuss the impact that these observations would have on our understanding of the fundamental models behind the string networks. overall, we prove that lisa has great potential for probing cosmic string models and may reach tensions as low as $ g \ mu = 10 ^ { - 16 } - 10 ^ { - 17 } $, which translates into energy scales of the order $ 10 ^ { 11 } ~ \ text { gev } $.
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arxiv:2405.03740
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recently, a supersymmetric model of dark energy coupled to cold dark matter, the supersymmetron, has been proposed. in the absence of cold dark matter, the supersymmetron field converges to a supersymmetric minimum with a vanishing cosmological constant. when cold dark matter is present, the supersymmetron evolves to a matter dependent minimum where its energy density does not vanish and could lead to the present acceleration of the universe. the supersymmetron generates a short ranged fifth force which evades gravitational tests. it could lead to observable signatures on structure formation due to a very strong coupling to dark matter. we investigate the cosmological evolution of the field, focusing on the linear perturbations and the spherical collapse and find that observable modifications in structure formation can indeed exist. unfortunately, we find that when the growth - rate of perturbations is in agreement with observations, an additional cosmological constant is required to account for dark energy. in this case, effects on large scale structures are still present at the non - linear level which are investigated using the spherical collapse approach.
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arxiv:1112.3676
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retrieval - augmented generation ( rag ) improves large language model ( llm ) performance on knowledge - intensive tasks but depends heavily on initial search query quality. current methods, often using reinforcement learning ( rl ), typically focus on query formulation or reasoning over results, without explicitly encouraging persistence after a failed search. we introduce rezero ( retry - zero ), a novel rl framework that directly rewards the act of retrying a search query following an initial unsuccessful attempt. this incentivizes the llm to explore alternative queries rather than prematurely halting. rezero demonstrates significant improvement, achieving 46. 88 % accuracy compared to a 25 % baseline. by rewarding persistence, rezero enhances llm robustness in complex information - seeking scenarios where initial queries may prove insufficient.
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arxiv:2504.11001
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proposing grasp poses for novel objects is an essential component for any robot manipulation task. planning six degrees of freedom ( dof ) grasps with a single camera, however, is challenging due to the complex object shape, incomplete object information, and sensor noise. in this paper, we present a 6 - dof contrastive grasp proposal network ( cgpn ) to infer 6 - dof grasps from a single - view depth image. first, an image encoder is used to extract the feature map from the input depth image, after which 3 - dof grasp regions are proposed from the feature map with a rotated region proposal network. feature vectors that within the proposed grasp regions are then extracted and refined to 6 - dof grasps. the proposed model is trained offline with synthetic grasp data. to improve the robustness in reality and bridge the simulation - to - real gap, we further introduce a contrastive learning module and variant image processing techniques during the training. cgpn can locate collision - free grasps of an object using a single - view depth image within 0. 5 seconds. experiments on a physical robot further demonstrate the effectiveness of the algorithm.
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arxiv:2103.15995
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in this paper we describe the overall idea and results of a recently proposed radio access technique based on filter bank multicarrier ( fbmc ) communication system using two orthogonal polarizations : dual - polarization fbmc ( dp - fbmc ). using this system we can alleviate the intrinsic interference problem in fbmc systems. this enables use of all the multicarrier techniques used in cyclic - prefix orthogonal frequency - division multiplexing ( cp - ofdm ) systems for channel equalization, multiple - input / multiple - output ( mimo ) processing, etc., without using the extra processing required for conventional fbmc. dp - fbmc also provides other interesting advantages over cp - ofdm and fbmc such as more robustness in multipath fading channels, and more robustness to receiver carrier frequency offset ( cfo ) and timing offset ( to ). for dp - fbmc we propose three different structures based on different multiplexing techniques in time, frequency, and polarization. we will show that one of these structures has exactly the same system complexity and equipment as conventional fbmc. in our simulation results dp - fbmc has better bit error ratio ( ber ) performance in dispersive channels. based on these results, dp - fbmc has potential as a promising candidate for future wireless communication systems.
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arxiv:1806.05143
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we model and analyze heterogeneous cellular networks with multiple antenna bss ( multi - antenna hetnets ) with k classes or tiers of base stations ( bss ), which may differ in terms of transmit power, deployment density, number of transmit antennas, number of users served, transmission scheme, and path loss exponent. we show that the cell selection rules in multi - antenna hetnets may differ significantly from the single - antenna hetnets due to the possible differences in multi - antenna transmission schemes across tiers. while it is challenging to derive exact cell selection rules even for maximizing signal - to - interferenceplus - noise - ratio ( sinr ) at the receiver, we show that adding an appropriately chosen tier - dependent cell selection bias in the received power yields a close approximation. assuming arbitrary selection bias for each tier, simple expressions for downlink coverage and rate are derived. for coverage maximization, the required selection bias for each tier is given in closed form. due to this connection with biasing, multi - antenna hetnets may balance load more naturally across tiers in certain regimes compared to single - antenna hetnets, where a large cell selection bias is often needed to offload traffic to small cells.
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arxiv:1310.6795
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in this paper, we present a comprehensive study on the convergence properties of adam - family methods for nonsmooth optimization, especially in the training of nonsmooth neural networks. we introduce a novel two - timescale framework that adopts a two - timescale updating scheme, and prove its convergence properties under mild assumptions. our proposed framework encompasses various popular adam - family methods, providing convergence guarantees for these methods in training nonsmooth neural networks. furthermore, we develop stochastic subgradient methods that incorporate gradient clipping techniques for training nonsmooth neural networks with heavy - tailed noise. through our framework, we show that our proposed methods converge even when the evaluation noises are only assumed to be integrable. extensive numerical experiments demonstrate the high efficiency and robustness of our proposed methods.
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arxiv:2305.03938
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the self - rationalising capabilities of large language models ( llms ) have been explored in restricted settings, using task / specific data sets. however, current llms do not ( only ) rely on specifically annotated data ; nonetheless, they frequently explain their outputs. the properties of the generated explanations are influenced by the pre - training corpus and by the target data used for instruction fine - tuning. as the pre - training corpus includes a large amount of human - written explanations " in the wild ", we hypothesise that llms adopt common properties of human explanations. by analysing the outputs for a multi - domain instruction fine - tuning data set, we find that generated explanations show selectivity and contain illustrative elements, but less frequently are subjective or misleading. we discuss reasons and consequences of the properties ' presence or absence. in particular, we outline positive and negative implications depending on the goals and user groups of the self - rationalising system.
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arxiv:2402.10532
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we describe a non - parametric approach for accurate determination of the slowest relaxation eigenvectors of molecular dynamics. the approach is blind as it uses no system specific information. in particular, it does not require a functional form with many parameters to closely approximate eigenvectors, e. g., a neural network, and thus no extensive expertise with the system. the power of the approach is illustrated on long atomistic protein folding trajectories. the determined eigenvectors pass a stringent validation test at timescale of 0. 2 ns, much shorter than alternative approaches.
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arxiv:2005.02782
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selective plane illumination microscopy ( spim ) is an optical sectioning imaging approach based on orthogonal light pathways for excitation and detection. the excitation pathway has an inverse relation between the optical sectioning strength and the effective field of view ( fov ). multiple approaches exist to extend the effective fov, and here we focus on remote focusing to axially scan the light sheet, synchronized with a cmos camera ' s rolling shutter. a typical axially scanned spim configuration for imaging large samples utilizes a tunable optic for remote focusing, paired with air objectives focused into higher refractive index media. to quantitatively explore the effect of remote focus choices and sample space refractive index mismatch on light sheet intensity distributions, we developed a computational model integrating ray tracing and field propagation. we validate our model ' s performance against experimental light sheet profiles for various spim configurations. our findings indicate that optimizing the position of the sample chamber relative to the excitation optics can enhance image quality by balancing aberrations induced by refractive index mismatch. we validate this prediction using a homebuilt, large sample axially scanned spim configuration and calibration samples.
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arxiv:2407.18862
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we examine the effect of a threshold bias on the power spectrum and the bispectrum in an ensemble of numerical simulations ( gaussian initial perturbations with power law spectra p ( k ) \ sim k ^ n, n = + 1, 0, - 1, - 2 ) and compare our results with theoretical predictions. our simulations are evolved sufficiently that on the scale where we apply the threshold the rms fluctuation has developed significantly into the nonlinear regime. thus, predictions based on perturbation theory do not necessarily apply. nevertheless, we find our results for the power spectrum, biased power simply amplified by a numerical factor, follow predicted trends, far beyond the regime where perturbation theory is expected to be valid. we find that the biased bispectrum continues to follow the so - called hierarchical form, with reduced three - point amplitude q \ approx 1 in the strongly nonlinear regime, independent of initial spectrum. in the quasi - linear perturbative regime the three - point amplitude depends on configuration shape, a behavior that is found to give useful information about the amount of bias without information about the unbiased matter distribution.
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arxiv:astro-ph/9404037
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we study the sodium - iridates model on the honeycomb lattice with both bcs pairing potential and hubbard interaction term. it is shown that this model can be exactly solved with appropriate choices of amplitude of pairing gaps, where the interacting terms are transformed to external field terms. the band structures of these exact solutions on both torus and cylinder geometry are discussed in great details. it is found that the ground state assumes an anti - ferromagnetic configuration, which breaks the time reversal symmetry spontaneously and renders the superconductor topologically trivial. on the other hand, the nontrivial topology is preserved with ferromagnetic configuration and can be characterized by the isospin chern number.
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arxiv:2010.01754
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it has been discovered before ( arxiv : 2306. 07676 ) that for the selectivity gain due to fluctuations in the process of primary odor reception by olfactory receptor neuron ( orn ) there exists an optimal concentration of odors at which increased selectivity is mostly manifested. we estimate by means of numerical simulation what could be the gain value at that concentration by modeling orn as a leaky integrate - and - fire neuron with membrane populated by receptor proteins r which bind and release odor molecules randomly. each r is modeled as a ligand - gated ion channel, and binding - releasing is modeled as a markov stochastic process. possible values for the selectivity gain are calculated for orn parameters suggested by experimental data. keywords : orn, selectivity, receptor proteins, fluctuations, stochastic process, markov process
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arxiv:2504.10401
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we present a list of distances and peculiar velocities for 1623 rfgc galaxies for three models of collective large - scale galaxy motion on distances about $ 100 h ^ { - 1 } $ mpc. it is based upon the article [ arxiv : 0910. 4640 ]. the ascii version of the list can be downloaded from the ao knu website : http : / / www. observ. univ. kiev. ua / data / rfgcvpec. zip
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arxiv:0911.3102
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we have explored prevailing modes of galaxy growth for redshifts z ~ 6 - 14, comparing substantially overdense and normal regions of the universe, using high - resolution zoom - in cosmological simulations. such rare overdense regions have been projected to host high - z quasars. we demonstrate that galaxies in such environments grow predominantly by a smooth accretion from cosmological filaments which dominates the mass input from major, intermediate and minor mergers. we find that by z ~ 6, the accumulated galaxy mass fraction from mergers falls short by a factor of 10 of the cumulative accretion mass for galaxies in the overdense regions, and by a factor of 5 in the normal environments. moreover, the rate of the stellar mass input from mergers also lies below that of an in - situ star formation ( sf ) rate. the fraction of stellar masses in galaxies contributed by mergers in overdense regions is ~ 12 %, and ~ 33 % in the normal regions, at these redshifts. our median sf rates for ~ few x 10 ^ 9 mo galaxies agrees well with the recently estimated rates for z ~ 7 galaxies from spitzer ' s surf - up survey. finally, we find that the main difference between the normal and overdense regions lies in the amplified growth of massive galaxies in massive dark matter halos. this leads to the formation of > = 10 ^ { 10 } mo galaxies due to the ~ 100 - fold increase in mass during the above time period. such galaxies are basically absent in the normal regions at these redshifts.
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arxiv:1407.2614
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we show how complexity theory can be introduced in machine learning to help bring together apparently disparate areas of current research. we show that this new approach requires less training data and is more generalizable as it shows greater resilience to random attacks. we investigate the shape of the discrete algorithmic space when performing regression or classification using a loss function parametrized by algorithmic complexity, demonstrating that the property of differentiation is not necessary to achieve results similar to those obtained using differentiable programming approaches such as deep learning. in doing so we use examples which enable the two approaches to be compared ( small, given the computational power required for estimations of algorithmic complexity ). we find and report that ( i ) machine learning can successfully be performed on a non - smooth surface using algorithmic complexity ; ( ii ) that parameter solutions can be found using an algorithmic - probability classifier, establishing a bridge between a fundamentally discrete theory of computability and a fundamentally continuous mathematical theory of optimization methods ; ( iii ) a formulation of an algorithmically directed search technique in non - smooth manifolds can be defined and conducted ; ( iv ) exploitation techniques and numerical methods for algorithmic search to navigate these discrete non - differentiable spaces can be performed ; in application of the ( a ) identification of generative rules from data observations ; ( b ) solutions to image classification problems more resilient against pixel attacks compared to neural networks ; ( c ) identification of equation parameters from a small data - set in the presence of noise in continuous ode system problem, ( d ) classification of boolean nk networks by ( 1 ) network topology, ( 2 ) underlying boolean function, and ( 3 ) number of incoming edges.
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arxiv:1910.02758
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simulating sample correlation matrices is important in many areas of statistics. approaches such as generating gaussian data and finding their sample correlation matrix or generating random uniform $ [ - 1, 1 ] $ deviates as pairwise correlations both have drawbacks. we develop an algorithm for adding noise, in a highly controlled manner, to general correlation matrices. in many instances, our method yields results which are superior to those obtained by simply simulating gaussian data. moreover, we demonstrate how our general algorithm can be tailored to a number of different correlation models. using our results with a few different applications, we show that simulating correlation matrices can help assess statistical methodology.
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arxiv:1106.5834
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highly polarizable metastable he * ( $ \ mathrm { 2 ^ 3s } $ ) and ne * ( $ \ mathrm { 2 ^ 3p } $ ) atoms have been diffracted from a 100 nm period silicon nitride transmission grating and the van der waals coefficients $ c _ 3 $ for the interaction of the excited atoms with the silicon nitride surface have been determined from the diffraction intensities out to the 10th order. the results agree with calculations based on the non - retarded lifshitz formula.
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arxiv:quant-ph/0112173
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the decays eta, eta - prime - > pi ^ + pi ^ - gamma are investigated within an approach that combines one - loop chiral perturbation theory with a coupled channel bethe - salpeter equation which satisfies unitarity constraints and generates vector mesons dynamically from composite states of two pseudoscalar mesons. it is furthermore shown that the inclusion of the eta - prime as a dynamical degree of freedom does not renormalize the wess - zumino - witten term.
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arxiv:hep-ph/0405039
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due to its decentralized nature, federated learning ( fl ) lends itself to adversarial attacks in the form of backdoors during training. the goal of a backdoor is to corrupt the performance of the trained model on specific sub - tasks ( e. g., by classifying green cars as frogs ). a range of fl backdoor attacks have been introduced in the literature, but also methods to defend against them, and it is currently an open question whether fl systems can be tailored to be robust against backdoors. in this work, we provide evidence to the contrary. we first establish that, in the general case, robustness to backdoors implies model robustness to adversarial examples, a major open problem in itself. furthermore, detecting the presence of a backdoor in a fl model is unlikely assuming first order oracles or polynomial time. we couple our theoretical results with a new family of backdoor attacks, which we refer to as edge - case backdoors. an edge - case backdoor forces a model to misclassify on seemingly easy inputs that are however unlikely to be part of the training, or test data, i. e., they live on the tail of the input distribution. we explain how these edge - case backdoors can lead to unsavory failures and may have serious repercussions on fairness, and exhibit that with careful tuning at the side of the adversary, one can insert them across a range of machine learning tasks ( e. g., image classification, ocr, text prediction, sentiment analysis ).
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arxiv:2007.05084
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systemic racism is a ubiquitous theme in societies worldwide and plays a central role in shaping our economic, social, and academic institutions. the vera c. rubin observatory is a major us ground - based facility based in chile with international participation. the observatory is an example of excellence and will deliver the largest survey of the sky ever attempted. rubin ' s full scientific and social potential can not be attained without addressing systemic racism and associated barriers to equity, diversity, and inclusion ( edi ). during rubin ' s 2021 virtual project and community workshop ( pcw ), the annual rubin community - based meeting, an anti - black racism workshop took place, facilitated by ' the bipoc project ' organization. about 60 members from different parts of the rubin ecosystem participated. we describe the motivation, organization, challenges, outcomes, and near - and long - term goals of this workshop.
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arxiv:2310.12177
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let s be the set of scalings 1, 2, 3, 4,... and consider the corresponding set of scaled lattices in the plane. in this paper averaging operators are defined for plaquette functions on a lattice to plaquette functions on a coarser lattice for all scale factors and their coherence is proved. this generalizes the averaging operators introduced by balaban and federbush. there are such coherent families of averaging operators for any dimension d and not only for d = 2. finally there are uniqueness theorems saying that in a sense, besides a form of straightforward averaging, the weights used are the only ones that give coherent families of averaging operators.
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arxiv:math-ph/0410046
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the phase diagram for the interacting fermions in weak coupling is described by the perturbative renormalization group equations. due to the lack of analytic solutions for these coupled non - linear differential equations, it is rather subtle to tell which couplings are relevant or irrelevant. we propose a powerful classification scheme to build up the hierarchy of the relevant couplings by a scaling ansatz found numerically. to demonstrate its superiority over the conventional classification for the relevant couplings, we apply this scheme to a controversial phase transition in the two - leg ladder and show that it should be a non - trivial crossover instead. the scaling ansatz we propose here can classify the relevant couplings in hierarchical order without any ambiguity and can improve significantly how we interpret the numerical outcomes in general renormalization group methods.
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arxiv:0911.0166
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we consider evaluation methods for payoffs with an inherent financial risk as encountered for instance for portfolios held by pension funds and insurance companies. pricing such payoffs in a way consistent to market prices typically involves combining actuarial techniques with methods from mathematical finance. we propose to extend standard actuarial principles by a new market - consistent evaluation procedure which we call ` two step market evaluation. ' this procedure preserves the structure of standard evaluation techniques and has many other appealing properties. we give a complete axiomatic characterization for two step market evaluations. we show further that in a dynamic setting with a continuous stock prices process every evaluation which is time - consistent and market - consistent is a two step market evaluation. we also give characterization results and examples in terms of g - expectations in a brownian - poisson setting.
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arxiv:1109.1749
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we introduce a scissors congruence $ k $ - theory spectrum which lifts the equivariant scissors congruence groups for compact $ g $ - manifolds with boundary, and we show that on $ \ pi _ 0 $ this is the source of a spectrum level lift of the burnside ring valued equivariant euler characteristic of a compact $ g $ - manifold. we also show that the equivariant scissors congruence groups for varying subgroups assemble into a mackey functor, which is a shadow of a conjectural higher genuine equivariant structure.
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arxiv:2501.06928
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the majority of thermonuclear explosions in the universe seem to proceed in a rather standardised way, as explosions of carbon - oxygen ( co ) white dwarfs in binary systems, leading to ' normal ' type ia supernovae ( sne ia ). however, over the years a number of objects have been found which deviate from normal sne ia in their observational properties, and which require different and not seldom more extreme progenitor systems. while the ' traditional ' classes of peculiar sne ia - luminous ' 91t - like ' and faint ' 91bg - like ' objects - have been known since the early 1990s, other classes of even more unusual transients have only been established 20 years later, fostered by the advent of new wide - field sn surveys such as the palomar transient factory. these include the faint but slowly declining ' 02es - like ' sne, ' ca - rich ' transients residing in the luminosity gap between classical novae and supernovae, extremely short - lived, fast - declining transients, and the very luminous so - called ' super - chandrasekhar ' sne ia. not all of them are necessarily thermonuclear explosions, but there are good arguments in favour of a thermonuclear origin for most of them. the aim of this chapter is to provide an overview of the zoo of potentially thermonuclear transients, reviewing their observational characteristics and discussing possible explosion scenarios.
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arxiv:1703.00528
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classical lattice yang - mills calculations provide a good way to understand different nonequilibrium phenomena in nonperturbatively overoccupied systems. above the debye scale the classical theory can be matched smoothly to kinetic theory. the aim of this work is to study the limits of this quasiparticle picture by determining the plasmon mass in classical real time yang - mills theory on a lattice in 3 spatial dimensions. we compare three methods to determine the plasmon mass : a hard thermal loop expression in terms of the particle distribution, an effective dispersion relation constructed from fields and their time derivatives, and by measuring oscillations between electric and magnetic field modes after artificially introducing a homogeneous color electric field. we find that a version of the dispersion relation that uses electric fields and their time derivatives agrees with the other methods within 50 %.
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arxiv:1610.03711
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quantum confinement was found to play a critical role in the formation of au ( 111 ) islands grown on the surface of mos2. these confinement effects are fully three dimensional, with a strong correlation to the relatively large fermi wavelength associated with the au ( 111 ) planes. the confinement effects result in preferred heights with a periodicity of nearly 2 nm and persist to much higher temperatures than are typically seen in electronic growth mode systems. these findings indicate the potential to explore electronic growth modes in a new class of systems based on metal - layered semiconductor interfaces.
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arxiv:1808.07579
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can a physicist make only a finite number of errors in the eternal quest to uncover the law of nature? this millennium - old philosophical problem, known as inductive inference, lies at the heart of epistemology. despite its significance to understanding human reasoning, a rigorous justification of inductive inference has remained elusive. at a high level, inductive inference asks whether one can make at most finite errors amidst an infinite sequence of observations, when deducing the correct hypothesis from a given hypothesis class. historically, the only theoretical guarantee has been that if the hypothesis class is countable, inductive inference is possible, as exemplified by solomonoff induction for learning turing machines. in this paper, we provide a tight characterization of inductive inference by establishing a novel link to online learning theory. as our main result, we prove that inductive inference is possible if and only if the hypothesis class is a countable union of online learnable classes, potentially with an uncountable size, no matter the observations are adaptively chosen or iid sampled. moreover, the same condition is also sufficient and necessary in the agnostic setting, where any hypothesis class meeting this criterion enjoys an $ \ tilde { o } ( \ sqrt { t } ) $ regret bound for any time step $ t $, while others require an arbitrarily slow rate of regret. our main technical tool is a novel non - uniform online learning framework, which may be of independent interest.
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arxiv:2312.00170
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a theorem of green says that a line bundle of degree at least $ 2g + 1 + p $ on a smooth curve $ x $ of genus $ g $ has property $ n _ p $. we prove a similar conclusion for certain singular, reducible curves $ x $ under suitable degree bounds over all irreducible components of $ x $.
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arxiv:1303.6002
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a path with three blocks $ p ( k, l, r ) $ is an oriented path formed by $ k $ - forward arcs followed by $ l $ - backward arcs then $ r $ - forward arcs. we prove that any $ ( 2k + 1 ) $ - chromatic digraph contains a path $ p ( 1, k, 1 ) $. however the existence of $ p ( 1, l, 1 ) $ with $ l \ geq k $ is established in any $ ( k + 4 ) $ - chromatic digraph. in general, we establish a quadratic bound for paths with three blocks.
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arxiv:2110.09933
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we evaluate properties of neutral mesons in nf = 2 dynamical simulations of tmqcd at maximal twist. the pion is explored - establishing the size of the isospin splitting ( an order a ^ 2 effect ). we investigate the eta ' ( the nf = 2 flavour singlet pseudoscalar meson ) and neutral rho and scalar mesons. we show that disconnected diagrams can be evaluated very efficiently in tmqcd using variance reduction methods.
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arxiv:0709.4564
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the nature of the superconducting transition in highly underdoped thick films of la $ _ { 2 - x } $ sr $ _ x $ cuo $ _ 4 $ ( $ x = 0. 07 $ and 0. 08 ) has been investigated using the in - plane transport measurements. the contribution of superconducting fluctuations to the conductivity in zero magnetic field, or paraconductivity, was determined from the magnetoresistance measured in fields applied perpendicular to the cuo $ _ 2 $ planes. both the temperature dependence of the paraconductivity above the transition and the nonlinear current - voltage ( $ i - v $ ) characteristics measured across it, exhibit the main signatures of the berezinskii - kosterlitz - thouless ( bkt ) transition. the quantitative comparison of the superfluid stiffness, extracted from the $ i - v $ data, with the renormalization - group results for the bkt theory, reveals a large value of the vortex - core energy. this finding is confirmed by the analysis of the paraconductivity obtained using different methods. the results strongly suggest that the characteristic energy scale controlling the bkt behavior in this layered system corresponds to the superfluid stiffness of a few layers.
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arxiv:1509.05719
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let $ g $ be a split group of type $ f _ 4 $ defined over a number field. we study the square - integrable automorphic representations of $ g $ that can be realized as leading terms of degenerate eisenstein series associated to various maximal parabolic subgroups. these representations appear in the residual spectrum. the local representation theory over finite places plays a central role in our work.
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arxiv:2205.06219
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in this note, we extend the scope of our previous work joint with bonnafoux, kattler, ni \ ~ no, sedano - mendoza, valdez and weitze - schmith \ " usen by showing the arithmeticity of the kontsevich - - zorich monodromies of infinite families of square - tiled surfaces of genera four, five and six.
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arxiv:2301.06894
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disjoint union = = = = given an indexed family of sets ( a i ) i ∈ i { \ displaystyle ( a _ { i } ) _ { i \ in { \ mathcal { i } } } }, there is a natural map i ∈ i a i → i ∈ i a i ( a, i ) ↦ a, { \ displaystyle { \ begin { aligned } \ bigsqcup _ { i \ in { \ mathcal { i } } } a _ { i } & \ to \ bigcup _ { i \ in { \ mathcal { i } } } a _ { i } \ \ ( a, i ) & \ mapsto a, \ end { aligned } } } which consists in " forgetting " the indices. this maps is always surjective ; it is bijective if and only if the a i { \ displaystyle a _ { i } } are pairwise disjoint, that is, all intersections of two sets of the family are empty. in this case, i ∈ i a i { \ textstyle \ bigcup _ { i \ in { \ mathcal { i } } } a _ { i } } and i ∈ i a i { \ textstyle \ bigsqcup _ { i \ in { \ mathcal { i } } } a _ { i } } are commonly identified, and one says that their union is the disjoint union of the members of the family. if a set is the disjoint union of a family of subsets, one says also that the family is a partition of the set. = = cardinality = = informally, the cardinality of a set s, often denoted | s |, is the number of its members. this number is the natural number n { \ displaystyle n } when there is a bijection between the set that is considered and the set { 1, 2, …, n } { \ displaystyle \ { 1, 2, \ ldots, n \ } } of the n { \ displaystyle n } first natural numbers. the cardinality of the empty set is 0 { \ displaystyle 0 }. a set with the cardinality of a natural number is called a finite set which is true for both cases. otherwise, one has an infinite set. the fact that natural numbers measure the cardinality of finite sets is the basis of the concept of natural number, and predates for
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https://en.wikipedia.org/wiki/Set_(mathematics)
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we investigate the number of sets of words that can be formed from a finite alphabet, counted by the total length of the words in the set. an explicit expression for the counting sequence is derived from the generating function, and asymptotics for large alphabet respectively large total word length are discussed. moreover, we derive a gaussian limit law for the number of words in a random finite language.
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arxiv:1001.4392
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in this invited short " news and views ", we review very briefly the history of pentaquark studies and the recent observations of the tetraquark and pentaquark states. we also discuss further experimental studies such as at belle - ii.
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arxiv:1508.06047
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this paper is about a parallel algorithm for tube - based model predictive control. the proposed control algorithm solves robust model predictive control problems suboptimally, while exploiting their structure. this is achieved by implementing a real - time algorithm that iterates between the evaluation of piecewise affine functions, corresponding to the parametric solution of small - scale robust mpc problems, and the online solution of structured equality constrained qps. the performance of the associated real - time robust mpc controllers is illustrated by a numerical case study.
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arxiv:1910.03271
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we show that the fermion mass spectrum may naturally be understood in terms of flavour democratic fixed points in supersymmetric theories which have a large domain of attraction in the presence of " strong unification ". our approach provides an alternative to the approximate yukawa texture zeroes of the froggatt - nielsen mechanism. we discuss a particular model based on a broken gauged $ su ( 3 ) _ l \ times su ( 3 ) _ r $ family symmetry which illustrates our approach.
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arxiv:hep-ph/9804446
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future wireless networks are poised to transform into integrated sensing and communication ( isac ) networks, unlocking groundbreaking services such as digital twinning. to harness the full potential of isac networks, it is essential to experimentally validate their sensing capabilities and the role of sensing in boosting communication. however, current prototype systems fall short in supporting multiple sensing functions or validating sensing - assisted communication. in response, we have developed an advanced isac prototype system that incorporates monostatic, bistatic, and network sensing modes. this system supports multimodal data collection and synchronization, ensuring comprehensive experimental validation. on the communication front, it excels in sensing - aided beam tracking and real - time high - definition video transmission. for sensing applications, it provides precise angle and range measurements, real - time angle - range imaging, and radio - based simultaneous localization and mapping ( slam ). our prototype aligns with the 5g new radio standard, offering scalability for up to 16 user equipments ( ues ) in uplink transmission and 10 ues in downlink transmission. real - world tests showcase the system ' s superior accuracy, with root mean square errors of 2. 3 degrees for angle estimation and 0. 3 meters ( m ) for range estimation. additionally, the estimation errors for multimodal - aided real - time radio slam localization and mapping are 0. 25 m and 0. 8 m, respectively.
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arxiv:2410.22956
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an emitter in the vicinity of a metal nanostructure is quenched by its decay through non - radiative channels, leading to the belief in a zone of inactivity for emitters placed within $ < $ 10nm of a plasmonic nanostructure. here we demonstrate that in tightly - coupled plasmonic resonators forming nanocavities " quenching is quenched " due to plasmon mixing. unlike isolated nanoparticles, plasmonic nanocavities show mode hybridization which massively enhances emitter excitation and decay via radiative channels. this creates ideal conditions for realizing single - molecule strong - coupling with plasmons, evident in dynamic rabi - oscillations and experimentally confirmed by laterally dependent emitter placement through dna - origami.
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arxiv:1612.02611
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the interplay between electron - electron and electron - phonon interactions is studied in a one - dimensional lattice model, by means of a variational monte carlo method based on generalized jastrow - slater wave functions. here, the fermionic part is constructed by a pair - product state, which explicitly depends on the phonon configuration, thus including the electron - phonon coupling in a backflow - inspired way. we report the results for the hubbard model in presence of the su - schrieffer - heeger coupling to optical phonons, both at half - filling and upon hole doping. at half - filling, the ground state is either a translationally invariant mott insulator, with gapless spin excitations, or a peierls insulator, which breaks translations and has fully gapped excitations. away from half - filling, the charge gap closes in both mott and peierls insulators, turning the former into a conventional luttinger liquid ( gapless in all excitation channels ). the latter, instead, retains a finite spin gap that closes only above a threshold value of the doping. even though consistent with the general theory of interacting electrons in one dimension, the existence of such a phase ( with gapless charge but gapped spin excitations ) has never been demonstrated in a model with repulsive interaction and with only two fermi points. since the spin - gapped metal represents the one - dimensional counterpart of a superconductor, our results furnish evidence that a true off - diagonal long - range order may exist in the two - dimensional case.
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arxiv:2407.03046
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