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this paper considers two - sided matching with budget constraints where one side ( firm or hospital ) can make monetary transfers ( offer wages ) to the other ( worker or doctor ). in a standard model, while multiple doctors can be matched to a single hospital, a hospital has a maximum quota : the number of doctors assigned to a hospital cannot exceed a certain limit. in our model, a hospital instead has a fixed budget : the total amount of wages allocated by each hospital to doctors is constrained. with budget constraints, stable matchings may fail to exist and checking for the existence is hard. to deal with the nonexistence of stable matchings, we extend the " matching with contracts " model of hatfield and milgrom, so that it handles approximately stable matchings where each of the hospitals ' utilities after deviation can increase by factor up to a certain amount. we then propose two novel mechanisms that efficiently return such a stable matching that exactly satisfies the budget constraints. in particular, by sacrificing strategy - proofness, our first mechanism achieves the best possible bound. furthermore, we find a special case such that a simple mechanism is strategy - proof for doctors, keeping the best possible bound of the general case. | arxiv:1711.07359 |
photodissociation regions ( pdrs ) and shocks give rise to conspicuous emission from rotationally and vibrationally excited molecular hydrogen. this line emission has now been studied with iso and from the ground in great detail. a remarkable discovery has been that toward the orion outflow and other shock - excited regions, the h _ 2 level populations show a very high excitation component. we suggest that these high - excitation populations may arise from non - thermal pumping processes, such as h _ 2 formation and high - velocity ion - molecule collision in partially dissociative shocks. in pdrs such as ngc 7023 however, formation pumping is always less important than fluorescent pumping. we furthermore present two hd emission line detections toward orion peak 1. this enables the first comparison of the h _ 2 and the hd excitation, which surprisingly turn out to be identical. | arxiv:astro-ph/0009384 |
many - body hydrodynamic interactions ( his ) play an important role in the dynamics of fluid suspensions. while many - body his have been studied extensively using particle simulations, there is a dearth of experimental frameworks with which to quantify fluid - mediated multi - body interactions. to address this, we design an experimental method that utilizes optical laser tweezers for quantifying fluid - mediated colloidal interactions with exquisite precision and control. by inducing translation - rotation hydrodynamic coupling between trapped fluorescently - labeled colloids, we obtain a direct reporter of few - to many - body his experimentally. we leverage the torque - free nature of laser tweezers to enable sensitive measurements of signals between trapped colloids. first, we measure the pair hi between a stationary tracer probe and a translating particle as a function of their separation distance. we discover that our technique can precisely quantify distant fluid disturbances that are generated by ~ 2 pn of hydrodynamic force at 12 particle radii of separation. to study the effect of many - body his, we measure the rotational mobility of a probe in a three - particle setup and in a model material, a two - dimensional hexagonally - close - packed lattice, that undergoes oscillatory strain. respectively, we discover that the probe ' s rotation can reverse in certain three - body configurations, and we find that rotational mobility in the crystalline array is strongly attenuated by particle rigidity. experimental measurements are corroborated by microhydrodynamic theory and stokesian dynamics simulations with excellent agreement, highlighting our ability to measure accurately many - body his. lastly, we extend our theoretical framework to manipulate colloidal - scale fluid flows. with experimental validation, we compute the required trajectory of a moving particle to induce a desired angular velocity of a probe. | arxiv:2502.09841 |
we show that the ( 2 + 1 ) - dimensional massless dirac equation, which includes a tilt term, can be reduced to the biconfluent heun equation for a broad range of scalar confining potentials, including the well - known morse potential. applying these solutions, we investigate a bipolar electron waveguide in 8 - $ pmmn $ borophene, formed by a well and barrier, both described by the morse potential. we demonstrate that the ability of two - dimensional materials with tilted dirac cones to localize electrons in both a barrier and a well can be harnessed to create pseudogaps in their electronic spectrum. these pseudogaps can be tuned through varying the applied top - gate voltage. potential opto - valleytronic and terahertz applications are discussed. | arxiv:2402.08600 |
spring - antispring systems have been investigated as possible low - frequency seismic isolation in high - precision optical experiments. these systems provide the possibility to tune the fundamental resonance frequency to, in principle, arbitrarily low values, and at the same time maintain a compact design of the isolation system. it was argued though that thermal noise in spring - antispring systems would not be as small as one may naively expect from lowering the fundamental resonance frequency. in this paper, we present a detailed calculation of the suspension thermal noise for a specific spring - antispring system, namely the roberts linkage. we find a concise expression of the suspension thermal noise spectrum, which assumes a form very similar to the well - known expression for a simple pendulum. it is found that while the roberts linkage can provide strong seismic isolation due to a very low fundamental resonance frequency, its thermal noise is rather determined by the dimension of the system. we argue that this is true for all horizontal mechanical isolation systems with spring - antispring dynamics. this imposes strict requirements on mechanical spring - antispring systems for the seismic isolation in potential future low - frequency gravitational - wave detectors as we discuss for the four main concepts : atom - interferometric, superconducting, torsion - bars, and conventional laser interferometer. | arxiv:1707.07309 |
motivated by recent experiments on electric transport through single molecules and quantum dots, we investigate a model for transport that allows for significant coupling between the electrons and a boson mode isolated on the molecule or dot. we focus our attention on the temperature dependent properties of the transport. in the holstein picture for polaronic transport in molecular crystals the temperature dependence of the conductivity exhibits a crossover from coherent ( band ) to incoherent ( hopping ) transport. here, the temperature dependence of the differential conductance on resonance does not show such a crossover, but is mostly determined by the lifetime of the resonant level on the molecule or dot. | arxiv:cond-mat/0203548 |
the surge of e - commerce reviews has presented a challenge in manually annotating the vast volume of reviews to comprehend their underlying aspects and sentiments. this research focused on leveraging weakly supervised learning to tackle aspect category learning and the sentiment classification of reviews. our approach involves the generation of labels for both aspects and sentiments, employing the snorkel framework of wsl, which incorporates aspect terms, review sentiment scores, and review ratings as sources of weak signals. this innovative strategy significantly reduces the laborious labeling efforts required for processing such extensive datasets. in this study, we deployed hybrid models, namely bilstm, cnn - bilstm, and cnn - lstm, which harness multiple inputs, including review text, aspect terms, and ratings. our proposed model employs two distinct loss functions : binary cross entropy with sigmoid activation for multi - label classification, enabling us to learn aspect labels such as quality, usability, service, size, and price, and categorical cross entropy with softmax activations for multi - class classification. subsequently, we meticulously evaluate the performance metrics of these three implemented models, including macro f1 score and macro precision. cnn & bi - lstm model attained 0. 78 and 0. 79 f1 scores on aspect and sentiment identification, respectively. the outcomes of this research are poised to make a substantial contribution to e - commerce platforms, offering an efficient and automated means to label and analyze vast troves of user reviews. | arxiv:2312.15526 |
we introduce a method to synthesize animator guided human motion across 3d scenes. given a set of sparse ( 3 or 4 ) joint locations ( such as the location of a person ' s hand and two feet ) and a seed motion sequence in a 3d scene, our method generates a plausible motion sequence starting from the seed motion while satisfying the constraints imposed by the provided keypoints. we decompose the continual motion synthesis problem into walking along paths and transitioning in and out of the actions specified by the keypoints, which enables long generation of motions that satisfy scene constraints without explicitly incorporating scene information. our method is trained only using scene agnostic mocap data. as a result, our approach is deployable across 3d scenes with various geometries. for achieving plausible continual motion synthesis without drift, our key contribution is to generate motion in a goal - centric canonical coordinate frame where the next immediate target is situated at the origin. our model can generate long sequences of diverse actions such as grabbing, sitting and leaning chained together in arbitrary order, demonstrated on scenes of varying geometry : hps, replica, matterport, scannet and scenes represented using nerfs. several experiments demonstrate that our method outperforms existing methods that navigate paths in 3d scenes. for more results we urge the reader to watch our supplementary video available at : https : / / www. youtube. com / watch? v = 0wzgsdyct4a & t = 1s | arxiv:2304.02061 |
the minima hopping global optimization method uses physically realizable molecular dynamics moves in combination with an energy feedback that guarantees the escape from any potential energy funnel. for the purpose of finding reactions pathways, we argue that minima hopping is particularly suitable as a guide through the potential energy landscape and as a generator for pairs of minima that can be used as input structures for methods capable of finding transition states between two minima. for lennard - jones benchmark systems we compared this minima hopping guided path search method to a known approach for the exploration of potential energy landscapes that is based on deterministic mode - following. although we used a stabilized mode - following technique that reliably allows to follow distinct directions when escaping from a local minimum, we observed that minima hopping guided path search is far superior in finding lowest - barrier reaction pathways. we therefore suggest that minima hopping guided path search can be used as a simple and efficient way to identify energetically low - lying chemical reaction pathways. finally we applied the minima hopping guided path search approach to 75 - atom and 102 - atom lennard jones systems. for the 75 - atom system we found pathways whose highest energies are significantly lower than the highest energy along the previously published lowest - barrier pathway. furthermore, many of these pathways contain a smaller number of intermediate transition states than the previously publish lowest - barrier pathway. in case of the 102 - atom system minima hopping guided path search found a previously unknown and energetically low - lying funnel. | arxiv:1401.8081 |
we address the computation of ground - state properties of chemical systems and realistic materials within the auxiliary - field quantum monte carlo method. the phase constraint to control the fermion phase problem requires the random walks in slater determinant space to be open - ended with branching. this in turn makes it necessary to use back - propagation ( bp ) to compute averages and correlation functions of operators that do not commute with the hamiltonian. several bp schemes are investigated and their optimization with respect to the phaseless constraint is considered. we propose a modified bp method for the computation of observables in electronic systems, discuss its numerical stability and computational complexity, and assess its performance by computing ground - state properties for several substances, including constituents of the primordial terrestrial atmosphere and small organic molecules. | arxiv:1707.02684 |
in this paper we initiate a program of rigorous analytical investigation of the paradoxical buckling behavior of circular cylindrical shells under axial compression. this is done by the development and systematic application of general theory of " near - flip " buckling of 3d slender bodies to cylindrical shells. the theory predicts scaling instability of the buckling load due to imperfections of load. it also suggests a more dramatic scaling instability caused by shape imperfections. the experimentally determined scaling exponent 1. 5 of the critical stress as a function of shell thickness appears in our analysis as the scaling of the lower bound on safe loads given by the korn constant. while the results of this paper fall short of a definitive explanation of the buckling behavior of cylindrical shells, we believe that our approach is capable of providing reliable estimates of the buckling loads of axially compressed cylindrical shells. | arxiv:1403.0287 |
instrumental variables ( iv ) regression is widely used to estimate causal treatment effects in settings where receipt of treatment is not fully random, but there exists an instrument that generates exogenous variation in treatment exposure. while iv can recover consistent treatment effect estimates, they are often noisy. building upon earlier work in biostatistics ( joffe and brensinger, 2003 ) and relating to an evolving literature in econometrics ( including abadie et al., 2019 ; huntington - klein, 2020 ; borusyak and hull, 2020 ), we study how to improve the efficiency of iv estimates by exploiting the predictable variation in the strength of the instrument. in the case where both the treatment and instrument are binary and the instrument is independent of baseline covariates, we study weighting each observation according to its estimated compliance ( that is, its conditional probability of being affected by the instrument ), which we motivate from a ( constrained ) solution of the first - stage prediction problem implicit to iv. the resulting estimator can leverage machine learning to estimate compliance as a function of baseline covariates. we derive the large - sample properties of a specific implementation of a weighted iv estimator in the potential outcomes and local average treatment effect ( late ) frameworks, and provide tools for inference that remain valid even when the weights are estimated nonparametrically. with both theoretical results and a simulation study, we demonstrate that compliance weighting meaningfully reduces the variance of iv estimates when first - stage heterogeneity is present, and that this improvement often outweighs any difference between the compliance - weighted and unweighted iv estimands. these results suggest that in a variety of applied settings, the precision of iv estimates can be substantially improved by incorporating compliance estimation. | arxiv:2108.03726 |
we present a monte carlo algorithm for selectively sampling radial distribution functions and effective interaction potentials in asymmetric liquid mixtures. we demonstrate its efficiency for hard - sphere mixtures, and for model systems with more general interactions, and compare our simulations with several analytical approximations. for interaction potentials containing a hard - sphere contribution, the algorithm yields the contact value of the radial distribution function. | arxiv:0705.4168 |
we investigate the effect of anharmonicity and interactions on the dynamics of an initially gaussian wavepacket in a weakly anharmonic potential. we note that depending on the strength and sign of interactions and anharmonicity, the quantum state can be either localized or delocalized in the potential. we formulate a classical model of this phenomenon and compare it to quantum simulations done for a self consistent potential given by the gross - pitaevskii equation. | arxiv:1212.2850 |
we give upper and lower bounds on the spectral radius of a graph in terms of the number of walks. we generalize a number of known results. | arxiv:math/0506259 |
since the launch of the fermi large area telescope in 2008 the number of known $ { \ gamma } $ - ray pulsars has increased immensely to over 200, many of which are also visible in the radio and x - ray bands. seyffert et al. ( 2011 ) demonstrated how constraints on the viewing geometries of some of these pulsars could be obtained by comparing their observed radio and $ { \ gamma } $ - ray light curves by eye to light curves from geometric models. while these constraints compare reasonably well with those yielded by more rigorous single - wavelength approaches, they are still a somewhat subjective representation of how well the models reproduce the observed radio and $ { \ gamma } $ - ray light curves. constructing a more rigorous approach is, however, made difficult by the large uncertainties associated with the $ { \ gamma } $ - ray light curves as compared to those associated with the radio light curves. naively applying a $ { \ chi } ^ { 2 } $ - like goodness - of - fit test to both bands invariably results in constraints dictated by the radio light curves. a number of approaches have been proposed to address this issue. in this paper we investigate these approaches and evaluate the results they yield. based on what we learn, we implement our own version of a goodness - of - fit test, which we then use to investigate the behaviour of the geometric models in multi - dimensional phase space. | arxiv:1611.01076 |
results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the cms experiment at the lhc in 2011. a novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. limits on the mass of the fourth - generation quarks and the relevant cabibbo - kobayashi - maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. the existence of mass - degenerate fourth - generation quarks with masses below 685 gev is excluded at 95 % confidence level for minimal off - diagonal mixing between the third - and the fourth - generation quarks. with a mass difference of 25 gev between the quark masses, the obtained limit on the masses of the fourth - generation quarks shifts by about + / - 20 gev. these results significantly reduce the allowed parameter space for a fourth generation of fermions. | arxiv:1209.1062 |
the heisenberg ferromagnet has symmetry group $ { \ rm su } ( 2 ) $. the property known as ferromagnetic ordering of energy levels ( foel ) states that the minimum energy eigenvalue among eigenvectors with total spin $ s $ is monotone decreasing as a function of $ s $. while this property holds for certain graphs such as open chains, in this note we demonstrate some counterexamples. we consider the spin 1 / 2 model on rings of length $ 2n $ for $ n = 2, 3,..., 8 $, and show that the minimum energy among all spin singlets is less than or equal to the minimum energy among all spin triplets, which violates foel. this also shows some counterexamples to the " aldous ordering " for the symmetric exclusion process. we also review some of the literature related to these examples. | arxiv:1107.1266 |
the emerging machine learning paradigm of decentralized federated learning ( dfl ) has the promise of greatly boosting the deployment of artificial intelligence ( ai ) by directly learning across distributed agents without centralized coordination. despite significant efforts on improving the communication efficiency of dfl, most existing solutions were based on the simplistic assumption that neighboring agents are physically adjacent in the underlying communication network, which fails to correctly capture the communication cost when learning over a general bandwidth - limited network, as encountered in many edge networks. in this work, we address this gap by leveraging recent advances in network tomography to jointly design the communication demands and the communication schedule for overlay - based dfl in bandwidth - limited networks without requiring explicit cooperation from the underlying network. by carefully analyzing the structure of our problem, we decompose it into a series of optimization problems that can each be solved efficiently, to collectively minimize the total training time. extensive data - driven simulations show that our solution can significantly accelerate dfl in comparison with state - of - the - art designs. | arxiv:2408.04705 |
the wave functions of the calogero - sutherland model are known to be expressible in terms of jack polynomials. a formula which allows to obtain the wave functions of the excited states by acting with a string of creation operators on the wave function of the ground state is presented and derived. the creation operators that enter in this formula of rodrigues - type for the jack polynomials involve dunkl operators. | arxiv:q-alg/9509003 |
symbolic execution is a powerful technique for program analysis. however, it has many limitations in practical applicability : the path explosion problem encumbers scalability, the need for language - specific implementation, the inability to handle complex dependencies, and the limited expressiveness of theories supported by underlying satisfiability checkers. often, relationships between variables of interest are not expressible directly as purely symbolic constraints. to this end, we present a new approach - - neuro - symbolic execution - - which learns an approximation of the relationship as a neural net. it features a constraint solver that can solve mixed constraints, involving both symbolic expressions and neural network representation. to do so, we envision such constraint solving as procedure combining smt solving and gradient - based optimization. we demonstrate the utility of neuro - symbolic execution in constructing exploits for buffer overflows. we report success on 13 / 14 programs which have difficult constraints, known to require specialized extensions to symbolic execution. in addition, our technique solves $ 100 $ \ % of the given neuro - symbolic constraints in $ 73 $ programs from standard verification and invariant synthesis benchmarks. | arxiv:1807.00575 |
i discuss some of what is known and unknown about the behavior of black hole binary systems in the quiescent accretion state. quiescence is important for several reasons : 1 ) the dominance of the companion star in the optical and ir wavelengths allows the binary parameters to be robustly determined - as an example, we argue that the longer proposed distance to the x - ray source gro j1655 - 40 is correct ; 2 ) quiescence represents the limiting case of an extremely low accretion rate, in which both accretion and jets can be observed ; 3 ) understanding the evolution and duration of the quiescent state is a key factor in determining the overall demographics of x - rary binaries, which has taken on a new importance in the era of gravitational wave astronomy. | arxiv:1610.09694 |
the goal of image ordinal estimation is to estimate the ordinal label of a given image with a convolutional neural network. existing methods are mainly based on ordinal regression and particularly focus on modeling the ordinal mapping from the feature representation of the input to the ordinal label space. however, the manifold of the resultant feature representations does not maintain the intrinsic ordinal relations of interest, which hinders the effectiveness of the image ordinal estimation. therefore, this paper proposes learning intrinsic consistent ordinal representations ( core ) from ordinal relations residing in groundtruth labels while encouraging the feature representations to embody the ordinal low - dimensional manifold. first, we develop an ordinal totally ordered set ( toset ) distribution ( otd ), which can ( i ) model the label embeddings to inherit ordinal information and measure distances between ordered labels of samples in a neighborhood, and ( ii ) model the feature embeddings to infer numerical magnitude with unknown ordinal information among the features of different samples. second, through otd, we convert the feature representations and labels into the same embedding space for better alignment, and then compute the kullback leibler ( kl ) divergence between the ordinal labels and feature representations to endow the latent space with consistent ordinal relations. third, we optimize the kl divergence through ordinal prototype - constrained convex programming with dual decomposition ; our theoretical analysis shows that we can obtain the optimal solutions via gradient backpropagation. extensive experimental results demonstrate that the proposed core can accurately construct an ordinal latent space and significantly enhance existing deep ordinal regression methods to achieve better results. | arxiv:2301.06122 |
we characterize ultrafilter convergence and ultrafilter compactness in linearly ordered and generalized ordered topological spaces. in such spaces, and for every ultrafilter $ d $, the notions of $ d $ - compactness and of $ d $ - pseudocompactness are equivalent. any product of initially $ \ lambda $ - compact generalized ordered topological spaces is still initially $ \ lambda $ - compact. on the other hand, preservation under products of certain compactness properties are independent from the usual axioms for set theory. | arxiv:1311.2285 |
when launching or landing a spacecraft on the regolith of a terrestrial surface, special attention needs to be paid to the rocket exhaust cratering effects. if the effects are not controlled, the rocket cratering could damage the spacecraft or other surrounding hardware. the cratering effects of a rocket landing a planet ' s surface are not understood well, especially for the lunar case with the plume expanding in vacuum. as a result, the blast effects cannot be estimated sufficiently using analytical theories. it is necessary to develop physics - based simulation tools in order to calculate mission - essential parameters. in this work we test out the scaling laws of the physics in regard to growth rate of the crater depth. this will provide the physical insight necessary to begin the physics - based modeling. | arxiv:2104.05176 |
storytelling aims to generate reasonable and vivid narratives based on an ordered image stream. the fidelity to the image story theme and the divergence of story plots attract readers to keep reading. previous works iteratively improved the alignment of multiple modalities but ultimately resulted in the generation of simplistic storylines for image streams. in this work, we propose a new pipeline, termed llams, to generate multimodal human - level stories that are embodied in expressiveness and consistency. specifically, by fully exploiting the commonsense knowledge within the llm, we first employ a sequence data auto - enhancement strategy to enhance factual content expression and leverage a textual reasoning architecture for expressive story generation and prediction. secondly, we propose sq - adatpter module for story illustration generation which can maintain sequence consistency. numerical results are conducted through human evaluation to verify the superiority of proposed llams. evaluations show that llams achieves state - of - the - art storytelling performance and 86 % correlation and 100 % consistency win rate as compared with previous sota methods. furthermore, ablation experiments are conducted to verify the effectiveness of proposed sequence data enhancement and sq - adapter. | arxiv:2403.07301 |
as part of their training all medical students and residents have to pass basic surgical tasks such as knot tying, needle - passing, and suturing. their assessment is typically performed in the operating room by surgical faculty where mistakes and failure by the student increases the operation time and cost. this evaluation is quantitative and has a low margin of error. simulation has emerged as a cost effective option but it lacks assessment or requires additional expensive hardware for evaluation. apps that provide training videos on surgical knot trying are available to students but none have evaluation. we propose a cascaded neural network architecture that evaluates a student ' s performance just from a video of themselves simulating a surgical knot tying task. our model converts video frame images into feature vectors with a pre - trained deep convolutional network and then models the sequence of frames with a temporal network. we obtained videos of medical students and residents from the robert wood johnson hospital performing knot tying on a standardized simulation kit. we manually annotated each video and proceeded to do a five - fold cross - validation study on them. our model achieves a median precision, recall, and f1 - score of 0. 71, 0. 66, and 0. 65 respectively in determining the level of knot related tasks of tying and pushing the knot. our mean precision score averaged across different probability thresholds is 0. 8. both our f1 - score and mean precision score are 8 % and 30 % higher than that of a recently published study for the same problem. we expect the accuracy of our model to further increase as we add more training videos to the model thus making it a practical solution that students can use to evaluate themselves. | arxiv:2312.14952 |
we re - examine resonant massless - neutrino conversions in a dense medium induced by flavour changing neutral current ( fcnc ) interactions. we show how the observed $ \ bar \ nu _ e $ energy spectra from sn1987a and the supernova $ r $ - process nucleosynthesis provide constraints on supersymmetric models with $ r $ parity violation, which are much more stringent than those obtained from the laboratory. we also suggest that resonant massless - neutrino conversions may play a positive role in supernova shock reheating. finally, we examine the constraints on explicit $ r $ - parity - violating fcncs in the presence of non - zero neutrino masses in the ev range, as indicated by present hot dark matter observations. | arxiv:hep-ph/9606445 |
in this new era of large data, it is important to make sure we do not miss any signs of new physics. using the publicly - available open data collected by the arxiv. org experiment in the \ texttt { hep - ph } channel, corresponding to a raw total integrated $ \ mathcal { l } $ iterature of 65, 276 papers, we perform a search for ` ` new physics ' ' and related signals. in the worst - case, we are able to detect ` ` new physics ' ' with ` ` the lhc ' ' at a significance level of at least $ 6. 5 \ sigma $. this ` ` new physics ' ' signature is primarily ` ` dark ' ' in nature, and is potentially axion ( - like ) dark matter. we also show the potential for further improvement in the future, and that ` ` new physics ' ' can be found with ` ` a future collider ' ' at at least $ 8. 9 \ sigma $, as well as the potential to find ` ` new physics ' ' without any collider at all. this search is performed using code that was $ 80 \ % $ written by machine learning methods. | arxiv:2503.22790 |
itzkowitz ' s problem asks whether every topological group $ g $ has equal left and right uniform structures provided that bounded left uniformly continuous real - valued function on $ g $ are right uniformly continuous. this paper provides a positive answer to this problem if $ g $ is of bounded exponent or, more generally, if there exist an integer $ p \ geq 2 $ and a nonempty open set $ u \ subset g $ such that the power map $ u \ ni g \ to g ^ p \ in g $ is left ( or right ) uniformly continuous. this also resolves the problem for periodic groups which are baire spaces. | arxiv:1003.3814 |
in this paper, we study the generic action for the scale - invariant theory of gravity and then by making use of the holographic methods, we compute some specific holographic measures of entanglement. precisely, we calculate the entanglement entropy, mutual and tripartite information and show that the mutual information is always positive while the tripartite information becomes negative. this indeed recovers the monogamy property of mutual information in this context. | arxiv:2103.02998 |
drawing fair samples from the boltzmann distribution of a statistical model is a challenging task for modern digital computers. we propose a physical implementation of a boltzmann sampler for the classical xy model by using a laser network. the xy spins are mapped onto the phases of multiple laser pulses in a fiber ring cavity and the steady - state distribution of phases naturally realizes the boltzmann distribution of the corresponding xy model. we experimentally implement the laser network by using an actively mode - locked fiber laser with optical delay lines, and demonstrate boltzmann sampling for a one - dimensional xy ring. | arxiv:1608.00358 |
understanding the natal kicks received by neutron stars ( nss ) during formation is a critical component of modelling the evolution of massive binaries. natal kicks are an integral input parameter for population synthesis codes, and have implications for the formation of double ns systems and their subsequent merger rates. however, many of the standard observational kick distributions that are used are obtained from samples created only from isolated nss. kick distributions derived in this way overestimate the intrinsic ns kick distribution. for nss in binaries, we can only directly estimate the effect of the natal kick on the binary system, instead of the natal kick received by the ns itself. here, for the first time, we present a binary kick distribution for nss with low - mass companions. we compile a catalogue of 145 nss in low - mass binaries with the best available constraints on proper motion, distance, and systemic radial velocity. for each binary, we use a three - dimensional approach to estimate its binary kick. we discuss the implications of these kicks on system formation, and provide a parametric model for the overall binary kick distribution, for use in future theoretical modelling work. we compare our results with other work on isolated nss and nss in binaries, finding that the ns kick distributions fit using only isolated pulsars underestimate the fraction of nss that receive low kicks. we discuss the implications of our results on modelling double ns systems, and provide suggestions on how to use our results in future theoretical works. | arxiv:2303.01059 |
stretched to dozens of times its original length. under tensile stress, plastic deformation is characterized by a strain hardening region and a necking region and finally, fracture ( also called rupture ). during strain hardening the material becomes stronger through the movement of atomic dislocations. the necking phase is indicated by a reduction in cross - sectional area of the specimen. necking begins after the ultimate strength is reached. during necking, the material can no longer withstand the maximum stress and the strain in the specimen rapidly increases. plastic deformation ends with the fracture of the material. = = failure = = = = = compressive failure = = = usually, compressive stress applied to bars, columns, etc. leads to shortening. loading a structural element or specimen will increase the compressive stress until it reaches its compressive strength. according to the properties of the material, failure modes are yielding for materials with ductile behavior ( most metals, some soils and plastics ) or rupturing for brittle behavior ( geomaterials, cast iron, glass, etc. ). in long, slender structural elements — such as columns or truss bars — an increase of compressive force f leads to structural failure due to buckling at lower stress than the compressive strength. = = = fracture = = = a break occurs after the material has reached the end of the elastic, and then plastic, deformation ranges. at this point forces accumulate until they are sufficient to cause a fracture. all materials will eventually fracture, if sufficient forces are applied. = = types of stress and strain = = engineering stress and engineering strain are approximations to the internal state that may be determined from the external forces and deformations of an object, provided that there is no significant change in size. when there is a significant change in size, the true stress and true strain can be derived from the instantaneous size of the object. = = = engineering stress and strain = = = consider a bar of original cross sectional area a0 being subjected to equal and opposite forces f pulling at the ends so the bar is under tension. the material is experiencing a stress defined to be the ratio of the force to the cross sectional area of the bar, as well as an axial elongation : subscript 0 denotes the original dimensions of the sample. the si derived unit for stress is newtons per square metre, or pascals ( 1 pascal = 1 pa = 1 n / m2 ), and strain is unitless. the stress – strain curve for this material is plotted | https://en.wikipedia.org/wiki/Deformation_(engineering) |
recent studies revealed that deep neural networks ( dnns ) are exposed to backdoor threats when training with third - party resources ( such as training samples or backbones ). the backdoored model has promising performance in predicting benign samples, whereas its predictions can be maliciously manipulated by adversaries based on activating its backdoors with pre - defined trigger patterns. currently, most of the existing backdoor attacks were conducted on the image classification under the targeted manner. in this paper, we reveal that these threats could also happen in object detection, posing threatening risks to many mission - critical applications ( $ e. g. $, pedestrian detection and intelligent surveillance systems ). specifically, we design a simple yet effective poison - only backdoor attack in an untargeted manner, based on task characteristics. we show that, once the backdoor is embedded into the target model by our attack, it can trick the model to lose detection of any object stamped with our trigger patterns. we conduct extensive experiments on the benchmark dataset, showing its effectiveness in both digital and physical - world settings and its resistance to potential defenses. | arxiv:2211.05638 |
in this work we analyse the constraints imposed by poincar \ ' e symmetry on the gravitational form factors appearing in the lorentz decomposition of the energy - momentum tensor matrix elements for massive states with arbitrary spin. by adopting a distributional approach, we prove for the first time non - perturbatively that the zero momentum transfer limit of the leading two form factors in the decomposition are completely independent of the spin of the states. it turns out that these constraints arise due to the general poincar \ ' e transformation and on - shell properties of the states, as opposed to the specific characteristics of the individual poincar \ ' e generators themselves. by expressing these leading form factors in terms of generalised parton distributions, we subsequently derive the linear and angular momentum sum rules for states with arbitrary spin. | arxiv:1905.11969 |
huge built - in electric fields have been predicted to exist in wurtzite iii - v nitrides thin films and multilayers. such fields originate from heterointerface discontinuities of the macroscopic bulk polarization of the nitrides. here we discuss the background theory, the role of spontaneous polarization in this context, and the practical implications of built - in polarization fields in nitride nanostructures. to support our arguments, we present detailed self - consistent tight - binding simulations of typical nitride qw structures in which polarization effects are dominant. | arxiv:cond-mat/9905186 |
the gravitational drift of ions relative to the electrons induces two type of waves in magnetized plasma ; ion acoustic ( io ) waves and lower hybrid ( lh ) waves. the io waves induced by the gravity are damped by electromagnetic ( em ) waves leads to the formation of lh waves. for higher wave vector, these lh wave results in to the resonant absorption and re - emission of em waves, called as gravity induced resonant emission ( gire ). a general formula has been derived for gire frequency is convergence of all fundamental quantities. | arxiv:1704.07225 |
an updated grid of stellar yields for low to intermediate - mass thermally - pulsing asymptotic giant branch ( agb ) stars are presented. the models cover a range in metallicity z = 0. 02, 0. 008, 0. 004, and 0. 0001, and masses between 1msun to 6msun. new intermediate - mass z = 0. 0001 agb models are also presented, along with a finer mass grid than used in previous studies. the yields are computed using an updated reaction rate network that includes the latest nena and mgal proton capture rates, with the main result that between ~ 6 to 30 times less na is produced by intermediate - mass models with hot bottom burning. in low - mass agb models we investigate the effect on the production of light elements of including some partial mixing of protons into the intershell region during the deepest extent of each third dredge - up episode. the protons are captured by the abundant 12c to form a 13c pocket. the 13c pocket increases the yields of 19f, 23na, the neutron - rich mg and si isotopes, 60fe, and 31p. the increase in 31p is by factors of ~ 4 to 20, depending on the metallicity. any structural changes caused by the addition of the 13c pocket into the he - intershell are ignored. however, the models considered are of low mass and any such feedback is likely to be small. further study is required to test the accuracy of the yields from the partial - mixing models. for each mass and metallicity, the yields are presented in a tabular form suitable for use in galactic chemical evolution studies or for comparison to the composition of planetary nebulae. | arxiv:0912.2142 |
it is shown that the kinetics of time - reversible chemical reactions having the same equilibrium constant but different initial conditions are closely related to one another by a directly measurable symmetry relation analogous to chemical detailed balance. in contrast to detailed balance, however, this relation does not require knowledge of the elementary steps that underlie the reaction, and remains valid in regimes where the concept of rate constants is ill - defined, such as at very short times and in the presence of low activation barriers. numerical simulations of a model of isomerization in solution are provided to illustrate the symmetry under such conditions, and potential applications in protein folding - unfolding are pointed out. | arxiv:cond-mat/0509191 |
reinforcement learning with human feedback ( rlhf ) is a widely used fine - tuning approach that aligns machine learning model, particularly language model ( lm ) with human preferences. there are typically multiple objectives driving the preference, hence humans find it easier to express per - objective comparisons rather than a global preference between two choices. multi - objective rlhf ( morlhf ) aims to use per - objective preference feedback and achieve pareto optimality among these objectives by aggregating them into a single unified objective for optimization. however, nearly all prior works rely on linear aggregation, which rules out policies that favor specific objectives such as the worst one. the only existing approach using non - linear aggregation is computationally expensive due to its reward - based nature and the need for retraining whenever the aggregation parameters change. in this work, we address this limitation by transforming the non - linear aggregation maximization problem into a series of sub - problems. each sub - problem involves only linear aggregation, making it computationally efficient to solve. we further extend our framework to handle multi - group scenarios, where each group has distinct weights for the objectives. our method enables achieving consensus or maximizing the aggregated objective across all groups. theoretically, we demonstrate that our algorithmic framework achieves sublinear regret and can be easily adapted to a reward - free algorithm. empirically, leveraging our theoretical insights, we propose a nearly training - free algorithm once the optimal policies for individual objectives are obtained. | arxiv:2502.15145 |
recent observations with the hinode solar optical telescope display an active region prominence whose fine threads oscillate in the vertical direction as they move along a path parallel to the photosphere. a seismological analysis of this event is carried out by taking advantage of the small radius of these structures compared to the total length of magnetic field lines, i. e. by using the thin tube approximation. this analysis reveals that the oscillatory period is only slightly modified by the existence of the flow and that the difference between the period of a flowing thread and a static one is below the error bars of these observations. moreover, although it is not possible to obtain values of the physical parameters, a lower bound for the alfv \ ' en speed ( ranging between 120 km s $ ^ { - 1 } $ and 350 km s $ ^ { - 1 } $ ) is obtained for each of the threads. such alfv \ ' en speeds agree with the intense magnetic fields and large densities usually found in active region prominences. | arxiv:0803.2649 |
in this paper, a scheme for the generation of long - living entanglement between two distant { \ lambda } - type three - level atoms separately trapped in two dissipative cavities is proposed. in this scheme, two dissipative cavities are coupled to their own non - markovian environments and two three - level atoms are driven by the classical fields. the entangled state between the two atoms is produced by performing bell state measurement ( bsm ) on photons leaving the dissipative cavities. using the time - dependent sch \ " ordinger equation, we obtain the analytical results for the evolution of the entanglement. it is revealed that, by manipulating the detunings of classical field, the long - living stationary entanglement between two atoms can be generated in the presence of dissipation | arxiv:1801.03283 |
we present calculations of several pp scattering cross sections with potential applications at the lhc. significantly large rates for momentum fraction, x, as low as 10 ^ - 7 are obtained, allowing for possible extraction of quark and gluon densities in the proton and nuclei down to these small x values provided a detector with good acceptance at maximal rapidities is used. | arxiv:hep-ph/9710490 |
self - supervised pre - training of image encoders is omnipresent in the literature, particularly following the introduction of masked autoencoders ( mae ). current efforts attempt to learn object - centric representations from motion in videos. in particular, siammae recently introduced a siamese network, training a shared - weight encoder from two frames of a video with a high asymmetric masking ratio ( 95 % ). in this work, we propose cropmae, an alternative approach to the siamese pre - training introduced by siammae. our method specifically differs by exclusively considering pairs of cropped images sourced from the same image but cropped differently, deviating from the conventional pairs of frames extracted from a video. cropmae therefore alleviates the need for video datasets, while maintaining competitive performances and drastically reducing pre - training and learning time. furthermore, we demonstrate that cropmae learns similar object - centric representations without explicit motion, showing that current self - supervised learning methods do not learn such representations from explicit object motion, but rather thanks to the implicit image transformations that occur between the two views. finally, cropmae achieves the highest masking ratio to date ( 98. 5 % ), enabling the reconstruction of images using only two visible patches. our code is available at https : / / github. com / alexandre - eymael / cropmae. | arxiv:2403.17823 |
it was noted already in the 90s that many classic graph classes, such as interval, chordal, and bipartite graphs, can be characterized by the existence of an ordering of the vertices avoiding some ordered subgraphs, called patterns. very recently, all the classes corresponding to patterns on three vertices ( including the ones mentioned above ) have been listed, and proved to be efficiently recognizable. in contrast, very little is known about patterns on four vertices. one of the few graph classes characterized by a pattern on four vertices is the class of intersection graphs of rectangles that are said to be grounded on a line. this class appears naturally in the study of intersection graphs, and similar grounded classes have recently attracted a lot of attention. this paper contains three parts. first, we make a survey of grounded intersection graph classes, summarizing all the known inclusions between these various classes. second, we show that the correspondence between a pattern on four vertices and grounded rectangle graphs is not an isolated phenomenon. we establish several other pattern characterizations for geometric classes, and show that the hierarchy of grounded intersection graph classes is tightly interleaved with the classes defined patterns on four vertices. we claim that forbidden patterns are a useful tool to classify grounded intersection graphs. finally, we give an overview of the complexity of the recognition of classes defined by forbidden patterns on four vertices and list several interesting open problems. | arxiv:2112.00629 |
recently, a new algorithm to test equivalence of two cyclic codes has been introduced which is efficient and produced useful results. in this work, we generalize this algorithm to constacyclic codes. as an application of the algorithm we found many constacyclic codes with good parameters and properties. in particular, we found 23 new codes that improve the minimum distances of bklcs. | arxiv:2108.08619 |
we experimentally demonstrate a method to control the relative amount of quantum and classical energy correlations between two photons from a pair emitted by spontaneous parametric downconversion. decoherence in the energy basis is achieved by applying random spectral phases on the photons. as a consequence a diverging temporal second order correlation function is observed and is explained by a mixture between an energy entangled pure state and a fully classically correlated mixte state. | arxiv:1711.10247 |
bit commitment protocols whose security is based on the laws of quantum mechanics alone are generally held to be impossible. in this paper we give a strengthened and explicit proof of this result. we extend its scope to a much larger variety of protocols, which may have an arbitrary number of rounds, in which both classical and quantum information is exchanged, and which may include aborts and resets. moreover, we do not consider the receiver to be bound to a fixed " honest " strategy, so that " anonymous state protocols ", which were recently suggested as a possible way to beat the known no - go results are also covered. we show that any concealing protocol allows the sender to find a cheating strategy, which is universal in the sense that it works against any strategy of the receiver. moreover, if the concealing property holds only approximately, the cheat goes undetected with a high probability, which we explicitly estimate. the proof uses an explicit formalization of general two party protocols, which is applicable to more general situations, and a new estimate about the continuity of the stinespring dilation of a general quantum channel. the result also provides a natural characterization of protocols that fall outside the standard setting of unlimited available technology, and thus may allow secure bit commitment. we present a new such protocol whose security, perhaps surprisingly, relies on decoherence in the receiver ' s lab. | arxiv:quant-ph/0605224 |
\ begin { abstract } in this paper, we consider the following system of difference equations \ begin { equation * } x _ { n + 1 } = \ alpha + \ dfrac { y _ { n } ^ p } { y _ { n - 2 } ^ p }, \ y _ { n + 1 } = \ alpha + \ dfrac { x _ { n } ^ q } { x _ { n - 2 } ^ q }, \ n = 0, 1, 2,... \ end { equation * } where parameters $ \ alpha, p, q \ in ( 0, \ infty ) $ and the initial values $ x _ { - i } $, $ y _ { - i } $ are arbitrary positive numbers for $ i = - 2, - 1, 0 $. our main aim is to investigate semi - cycle analysis of solutions of above system. also, we study the boundedness of the positive solutions and the global asymptotic stability of the equilibrium point in case $ \ alpha > 1 $, $ 0 < p, \ q \ leq 1 $. moreover, the rate of convergence of the solutions is established. finally, some numerical examples are given to illustrate our theoretical results. | arxiv:2108.05534 |
we present a detailed analysis of continuous time quantum walks ( ctqw ) with both position and transition defects defined at a single point in the line. analytical solutions of both traveling waves or bound states are obtained, which provide valuable insight into the dynamics of ctqw. the number of bound states is found to be critically dependent on the defect parameters, and the localized probability peaks can be readily obtained by projecting the ctqw wavefunction on to these bound states. the interference between two bound states are also observed in the case of a transition defect. the spreading of ctqw probability over the line can be finely tuned by varying the position and transition defect parameters, offering the possibility of precision quantum control of the system. | arxiv:1502.04289 |
we consider multi - robot systems under recurring tasks formalized as linear temporal logic ( ltl ) specifications. to solve the planning problem efficiently, we propose a bottom - up approach combining offline plan synthesis with online coordination, dynamically adjusting plans via real - time communication. to address action delays, we introduce a synchronization mechanism ensuring coordinated task execution, leading to a multi - agent coordination and synchronization framework that is adaptable to a wide range of multi - robot applications. the software package is developed in python and ros2 for broad deployment. we validate our findings through lab experiments involving nine robots showing enhanced adaptability compared to previous methods. additionally, we conduct simulations with up to ninety agents to demonstrate the reduced computational complexity and the scalability features of our work. | arxiv:2502.16531 |
the world has been affected by covid - 19 coronavirus. at the time of this study, the number of infected people in the united states is the highest globally ( 7. 9 million infections ). within the infected population, patients diagnosed with acute respiratory distress syndrome ( ards ) are in more life - threatening circumstances, resulting in severe respiratory system failure. various studies have investigated the infections to covid - 19 and ards by monitoring laboratory metrics and symptoms. unfortunately, these methods are merely limited to clinical settings, and symptom - based methods are shown to be ineffective. in contrast, vital signs ( e. g., heart rate ) have been utilized to early - detect different respiratory diseases in ubiquitous health monitoring. we posit that such biomarkers are informative in identifying ards patients infected with covid - 19. in this study, we investigate the behavior of covid - 19 on ards patients by utilizing simple vital signs. we analyze the long - term daily logs of blood pressure and heart rate associated with 70 ards patients admitted to five university of california academic health centers ( containing 42506 samples for each vital sign ) to distinguish subjects with covid - 19 positive and negative test results. in addition to the statistical analysis, we develop a deep neural network model to extract features from the longitudinal data. using only the first eight days of the data, our deep learning model is able to achieve 78. 79 % accuracy to classify the vital signs of ards patients infected with covid - 19 versus other ards diagnosed patients. | arxiv:2011.10470 |
large observational data are increasingly available in disciplines such as health, economic and social sciences, where researchers are interested in causal questions rather than prediction. in this paper, we examine the problem of estimating heterogeneous treatment effects using non - parametric regression - based methods, starting from an empirical study aimed at investigating the effect of participation in school meal programs on health indicators. firstly, we introduce the setup and the issues related to conducting causal inference with observational or non - fully randomized data, and how these issues can be tackled with the help of statistical learning tools. then, we review and develop a unifying taxonomy of the existing state - of - the - art frameworks that allow for individual treatment effects estimation via non - parametric regression models. after presenting a brief overview on the problem of model selection, we illustrate the performance of some of the methods on three different simulated studies. we conclude by demonstrating the use of some of the methods on an empirical analysis of the school meal program data. | arxiv:2009.06472 |
we study the hodge filtration on the local cohomology sheaves of a smooth complex algebraic variety along a closed subscheme z in terms of log resolutions, and derive applications regarding the local cohomological dimension, the du bois complex, local vanishing, and reflexive differentials associated to z. | arxiv:2108.05192 |
materials that have a hysteretic response to an external field are essential in modern information storage and processing technologies. the magnetization curves of several natural and artificial materials have previously been measured and explained in terms of the neel model, preisach phenomenological model, the creation, propagation, and annihilation of topological defects, or by resonant quantum tunnelling of the magnetization in single molecule magnets. however, a simple way to design the magnetic response of a material is missing. here, we propose and experimentally realize an elementary method to engineer hysteresis loops in metamaterials built out of dipolar chains. we show that by tuning the system ' s interactions and geometry we can induce magnetic responses with or without remanence at will. our findings pave the way for the rational design of hysteretical responses in a variety of physical systems such as dipolar cold atoms, ferroelectrics, or artificial magnetic lattices, among others. | arxiv:1710.08391 |
world models learn the consequences of actions in vision - based interactive systems. however, in practical scenarios such as autonomous driving, there commonly exists noncontrollable dynamics independent of the action signals, making it difficult to learn effective world models. to tackle this problem, we present a novel reinforcement learning approach named iso - dream, which improves the dream - to - control framework in two aspects. first, by optimizing the inverse dynamics, we encourage the world model to learn controllable and noncontrollable sources of spatiotemporal changes on isolated state transition branches. second, we optimize the behavior of the agent on the decoupled latent imaginations of the world model. specifically, to estimate state values, we roll - out the noncontrollable states into the future and associate them with the current controllable state. in this way, the isolation of dynamics sources can greatly benefit long - horizon decision - making of the agent, such as a self - driving car that can avoid potential risks by anticipating the movement of other vehicles. experiments show that iso - dream is effective in decoupling the mixed dynamics and remarkably outperforms existing approaches in a wide range of visual control and prediction domains. | arxiv:2205.13817 |
we reexamine the electronic structure of graphene on sic substrate by angle - resolved photoemission spectroscopy. we directly observed multiply cloning of dirac cone, in addition to ones previously attributed to reconstruction. the locations, relative distances and anisotropy of dirac cone replicas fully agree with the moir \ ' e pattern of graphene - sic heterostructure. our results provide a straightforward example of moir \ ' e potential modulation in engineering electronic structure with dirac fermions. | arxiv:2103.12735 |
wireless communications has become one of the fastest growing areas in our modern life and creates enormous impact on nearly every feature of our daily life. in this paper, the performance of m - ary modulations schemes ( mpsk, mqam, mfsk ) based wireless communication system on audio signal transmission over additive gaussian noise ( awgn ) channel are analyzed in terms of bit error probability as a function of snr. based on the results obtained in the present study, mpsk and mqam are showing better performance for lower modulation order whereas these are inferior with higher m. the ber value is smaller in mfsk for higher m, but it is worse due to the distortion in the reproduce signal at the receiver end. the lossless reproduction of recorded voice signal can be achieved at the receiver end with a lower modulation order. | arxiv:1203.1778 |
large hubbard u limit of the kane - mele model on a zigzag ribbon of honeycomb lattice near half - filling is studied via a renormalized mean - field theory. the ground state exhibits time - reversal symmetry ( trs ) breaking d + i d ' - wave superconductivity. at large spin - orbit coupling, the z2 phase with non - trivial spin chern number in the pure kane - mele model is persistent into the trs broken state ( called spin - chern phase ), and has two pairs of counter - propagating helical majorana modes at the edges. as the spin - orbit coupling is reduced, the system undergoes a topological quantum phase transition from the spin - chern to chiral superconducting states. possible relevance of our results to adatom - doped graphene and irridate compounds is discussed. | arxiv:1506.02584 |
we study the topology of $ sle $ curves for $ \ kappa > 4 $. more precisely, we show that, a. s., there is no homeomorphism $ \ phi : \ overline { \ mathbb { h } } \ rightarrow \ overline { \ mathbb { h } } $, taking the range of one independent $ sle $ curve to another for $ \ kappa \ in ( 4, 8 ) $. furthermore, we extend the result to $ \ kappa \ geq 8 $ by showing that there is no homeomorphism taking one $ sle $ curve to another, when viewed as curves modulo parametrization. | arxiv:2109.08277 |
exponential family random graph models ( ergms ) can be viewed as expressing a probability distribution on graphs arising from the action of competing social forces that make ties more or less likely, depending on the state of the rest of the graph. such forces often lead to a complex pattern of dependence among edges, with non - trivial large - scale structures emerging from relatively simple local mechanisms. while this provides a powerful tool for probing macro - micro connections, much remains to be understood about how local forces shape global outcomes. one simple question of this type is that of the conditions needed for social forces to stabilize a particular structure. we refer to this property as local stability and seek a general means of identifying the set of parameters under which a target graph is locally stable with respect to a set of alternatives. here, we provide a complete characterization of the region of the parameter space inducing local stability, showing it to be the interior of a convex cone whose faces can be derived from the change - scores of the sufficient statistics vis - a - vis the alternative structures. as we show, local stability is a necessary but not sufficient condition for more general notions of stability, the latter of which can be explored more efficiently by using the ` ` stable cone ' ' within the parameter space as a starting point. in addition, we show how local stability can be used to determine whether a fitted model implies that an observed structure would be expected to arise primarily from the action of social forces, versus by merit of the model permitting a large number of high probability structures, of which the observed structure is one. we also use our approach to identify the dyads within a given structure that are the least stable, and hence predicted to have the highest probability of changing over time. | arxiv:1908.09470 |
most evolution equations % or wave equations are partially integrable and, in order to explicitly integrate all possible cases, there exist several methods of complex analysis, but none is optimal. the theory of nevanlinna and wiman - valiron on the growth of the meromorphic solutions gives predictions and bounds, but it is not constructive and restricted to meromorphic solutions. the painleve ' approach via the a priori singularities of the solutions gives no bounds but it is often ( not always ) constructive. it seems that an adequate combination of the two methods could yield much more output in terms of explicit ( i. e. closed form ) analytic solutions. we review this question, mainly taking as an example the chaotic equation of kuramoto and sivashinsky nu u ' ' ' + b u ' ' + mu u ' + u ^ 2 / 2 + a = 0, nu nonzero, with nu, b, mu, a constants. | arxiv:nlin/0604063 |
knowledge - based visual question answering ( kvqa ) task aims to answer questions that require additional external knowledge as well as an understanding of images and questions. recent studies on kvqa inject an external knowledge in a multi - modal form, and as more knowledge is used, irrelevant information may be added and can confuse the question answering. in order to properly use the knowledge, this study proposes the following : 1 ) we introduce a novel semantic inconsistency measure computed from caption uncertainty and semantic similarity ; 2 ) we suggest a new external knowledge assimilation method based on the semantic inconsistency measure and apply it to integrate explicit knowledge and implicit knowledge for kvqa ; 3 ) the proposed method is evaluated with the ok - vqa dataset and achieves the state - of - the - art performance. | arxiv:2207.13242 |
analyzing ecological data often requires modeling the autocorrelation created by spatial and temporal processes. many of the statistical methods used to account for autocorrelation can be viewed as regression models that include basis functions. understanding the concept of basis functions enables ecologists to modify commonly used ecological models to account for autocorrelation, which can improve inference and predictive accuracy. understanding the properties of basis functions is essential for evaluating the fit of spatial or time - series models, detecting a hidden form of multicollinearity, and analyzing large data sets. we present important concepts and properties related to basis functions and illustrate several tools and techniques ecologists can use when modeling autocorrelation in ecological data. | arxiv:1606.05658 |
we derive a set of nontrivial relations between second - order transport coefficients which follow from the second law of thermodynamics upon considering a regime close to uniform rotation of the fluid. we demonstrate that extension of hydrodynamics by spin variable is equivalent to modifying conventional hydrodynamics by a set of second - order terms satisfying the relations we derived. we point out that a novel contribution to the heat current orthogonal to vorticity and temperature gradient reminiscent of the thermal hall effect is constrained by the second law. | arxiv:2011.12318 |
this paper presents a novel method for restoring digital videos via a deep plug - and - play ( pnp ) approach. under a bayesian formalism, the method consists in using a deep convolutional denoising network in place of the proximal operator of the prior in an alternating optimization scheme. we distinguish ourselves from prior pnp work by directly applying that method to restore a digital video from a degraded video observation. this way, a network trained once for denoising can be repurposed for other video restoration tasks. our experiments in video deblurring, super - resolution, and interpolation of random missing pixels all show a clear benefit to using a network specifically designed for video denoising, as it yields better restoration performance and better temporal stability than a single image network with similar denoising performance using the same pnp formulation. moreover, our method compares favorably to applying a different state - of - the - art pnp scheme separately on each frame of the sequence. this opens new perspectives in the field of video restoration. | arxiv:2209.02854 |
the transient accreting millisecond pulsar sax j1808. 4 - 3658 has shown several outbursts to date but the transition from outburst to quiescence has never been investigated in detail. thanks to the swift observing flexibility, we monitored for the first time the decay to quiescence during the 2005 outburst. at variance with other transients, wide luminosity variations are observed. in addition, close to quiescence, sax j1808. 4 - 3658 seems to switch between two different states. we interpret them in terms of the accretion states accessible to a magnetized, fast rotating neutron star. | arxiv:0807.4444 |
custodial $ su ( 2 ) $ breaking due to dynamical fermion masses is studied in a rather general context and it is shown how some well known limiting cases are correctly described. the type of ` ` gap equation ' ' which can systematically lead to extra negative contributions to the so - - called $ \ rho $ - - parameter is emphasized. furthermore general model independent features are discussed and it is shown how electro - - weak precision measurements can be sensitive to the fermion content and / or dynamical features of a given theory. | arxiv:hep-ph/9304269 |
we study the verification of maximally entangled states by virtue of the simplest measurement settings : local projective measurements without adaption. we show that optimal protocols are in one - to - one correspondence with complex projective 2 - designs constructed from orthonormal bases. optimal protocols with minimal measurement settings are in one - to - one correspondence with complete sets of mutually unbiased bases. based on this observation, optimal protocols are constructed explicitly for any local dimension, which can also be applied to estimating the fidelity with the target state and to detecting entanglement. in addition, we show that incomplete sets of mutually unbiased bases are optimal for verifying maximally entangled states when the number of measurement settings is restricted. moreover, we construct optimal protocols for the adversarial scenario in which state preparation is not trusted. the number of tests has the same scaling behavior as the counterpart for the nonadversarial scenario ; the overhead is no more than three times. we also show that the entanglement of the maximally entangled state can be certified with any given significance level using only one test as long as the local dimension is large enough. | arxiv:1901.09772 |
a search for flavor - changing neutral current ( fcnc ) processes in associated production of a top quark and higgs boson, with the higgs boson decaying to a pair of b quarks, is presented. to experimentally probe the top - higgs fcnc couplings, for the first time the single - top production is considered as a signal process. one isolated lepton and at least three reconstructed jets, among which at least two are identified as b quark jets, are found in the final state. the data sample corresponds to an integrated luminosity of $ 35. 9 \, \ mathrm { fb ^ { - 1 } } $ recorded by the cms experiment at the lhc in proton - proton collisions at $ \ sqrt { s } \, = \, 13 \, \ mathrm { tev } $ in 2016, and the final results are presented in the form of the observed and expected 95 \ % cl upper limits on the branching ratio of top quark decays. | arxiv:1711.07766 |
application of an in - plane magnetic field to rippled graphene will make the system be a plane with randomly distributed vector potentials. massless dirac fermions carrying charges on graphene are scattered by the vector potentials and magnetoresistance is induced proportional to the square of amplitude of in - plane magnetic field $ b _ { \ parallel } ^ 2 $. recently, lundeberg and folk proposed a formula showing dependence of the magnetoresistance on carrier density, in which the coefficient of $ b _ { \ parallel } ^ 2 $ is given by a functional of the height - correlation function $ c ( r ) $ of ripples. in the present paper, we give exact and explicit expressions of the coefficient for the two cases such that $ c ( r ) $ is ( i ) exponential and ( ii ) gaussian. the results are given using well - known special functions. numerical fitting of our solutions to experimental data were performed. it is shown that the experimental data are well - described by the formula for the gaussian height - correlation of ripples in the whole region of carrier density. the standard deviation $ z $ of ripple height and the correlation length $ r $ of ripples are evaluated, which can be compared with direct experimental measurements. | arxiv:1211.2046 |
in this paper, we employ an finite volume method ( fvm ) based on the heterogenous multiscale method ( hmm ), for the multiscale convection - diffusion - reaction problem. the optimal order convergence rate in h ^ 1 - norm is given for periodic medias. | arxiv:1512.06331 |
in the present work, we adopt a relativistic constituent quark model to depict the charmed strange meson spectroscopy, in which $ d _ { s0 } ( 2317 ) $ and $ d _ { s1 } ( 2460 ) $ are considered as the $ 1 ^ 3p _ 0 $ and $ 1p _ 1 ^ \ prime $ charmed strange mesons, respectively. by using the wave function obtained from the relativistic quark model, we further investigate the electric transitions between charmed strange mesons. we find the long wave length approximation is reasonable for the charmed strange meson radiative decay by comparing the results with different approximations. the estimated partial widths are all safely under the upper limits of the experimental data. moreover, we find the branching ratio of $ d _ { s1 } ( 2536 ) \ to d _ s ^ \ ast \ gamma / d _ s \ gamma $ are large enough to be detected, which could be searched by further experiments in belle ii and lhcb. | arxiv:2003.07988 |
hitherto unknown elementary particles can be searched for with atomic spectroscopy. we conduct such a search using a potential that results from the longitudinal polarization of a pseudovector particle. we show that such a potential, inversely proportional to the boson ' s mass squared, $ v \ propto 1 / m ^ 2 $, can stay finite at $ m \ to 0 $ if the theory is renormalizable. we also look for a pseudoscalar boson, which induces a contact spin - dependent potential that does not contribute to new forces searched for in experiments with macroscopic objects, but may be seen in atomic spectroscopy. we extract limits on the interaction constants of these potentials from the experimental spectra of antiprotonic helium, muonium, positronium, helium, and hydrogen. | arxiv:1911.05816 |
this is a generalization of the classic work of beilinson, lusztig and macpherson. in this paper ( and an appendix ) we show that the quantum algebras obtained via a blm - type stabilization procedure in the setting of partial flag varieties of type $ b / c $ are two ( modified ) coideal subalgebras of the quantum general linear lie algebra, $ \ dot { \ mathbf u } ^ { \ jmath } $ and $ \ dot { \ mathbf u } ^ { \ imath } $. we provide a geometric realization of the schur - type duality of bao - wang between such a coideal algebra and iwahori - hecke algebra of type $ b $. the monomial bases and canonical bases of the schur algebras and the modified coideal algebra $ \ dot { \ mathbf u } ^ { \ jmath } $ are constructed. in an appendix by three authors, a more subtle $ 2 $ - step stabilization procedure leading to $ \ dot { \ mathbf u } ^ { \ imath } $ is developed, and then monomial and canonical bases of $ \ dot { \ mathbf u } ^ { \ imath } $ are constructed. it is shown that $ \ dot { \ mathbf u } ^ { \ imath } $ is a subquotient of $ \ dot { \ mathbf u } ^ { \ jmath } $ with compatible canonical bases. moreover, a compatibility between canonical bases for modified coideal algebras and schur algebras is established. | arxiv:1404.4000 |
we study a class of infinite - dimensional singular stochastic control problems with applications in economic theory and finance. the control process linearly affects an abstract evolution equation on a suitable partially - ordered infinite - dimensional space x, it takes values in the positive cone of x, and it has right - continuous and nondecreasing paths. we first provide a rigorous formulation of the problem by properly defining the controlled dynamics and integrals with respect to the control process. we then exploit the concave structure of our problem and derive necessary and sufficient first - order conditions for optimality. the latter are finally exploited in a specification of the model where we find an explicit expression of the optimal control. the techniques used are those of semigroup theory, vector - valued integration, convex analysis, and general theory of stochastic processes. | arxiv:1904.11450 |
we show the equivalence of the 2d ising model to standard free euclidean lattice fermions of the wilson majorana type. the equality of the loop representations for the partition functions of both systems is established exactly for finite lattices with well - defined boundary conditions. the honeycomb lattice is particularly simple in this context and therefore discussed first and only then followed by the more familiar square lattice case. | arxiv:2003.01579 |
algorithmic bias is a major issue in machine learning models in educational contexts. however, it has not yet been studied thoroughly in asian learning contexts, and only limited work has considered algorithmic bias based on regional ( sub - national ) background. as a step towards addressing this gap, this paper examines the population of 5, 986 students at a large university in the philippines, investigating algorithmic bias based on students ' regional background. the university used the canvas learning management system ( lms ) in its online courses across a broad range of domains. over the period of three semesters, we collected 48. 7 million log records of the students ' activity in canvas. we used these logs to train binary classification models that predict student grades from the lms activity. the best - performing model reached auc of 0. 75 and weighted f1 - score of 0. 79. subsequently, we examined the data for bias based on students ' region. evaluation using three metrics : auc, weighted f1 - score, and madd showed consistent results across all demographic groups. thus, no unfairness was observed against a particular student group in the grade predictions. | arxiv:2405.09821 |
if $ f $ is a meromorphic function from the complex plane $ { \ mathbb c } $ to the extended complex plane $ \ overline { { \ mathbb c } } $, for $ r > 0 $ let $ n ( r ) $ be the maximum number of solutions in $ \ { z \ colon | z | \ leq r \ } $ of $ f ( z ) = a $ for $ a \ in \ overline { { \ mathbb c } } $, and let $ a ( r, f ) $ be the average number of such solutions. using a technique introduced by toppila, we exhibit a meromorphic function for which $ \ liminf _ { r \ to \ infty } n ( r ) / a ( r, f ) \ geq 1. 07328 $. | arxiv:2401.13808 |
we study the two time correlation for the noise driven dynamics of the double - well oscillator in the suzuki regime. it is seen that for very small noise strength the correaltion function shows a lack of translational invariance for very long times characterised by the suzuki scaling variable. we see that in this strongly out - of - equilibrium situation, the conventional mode - coupling approximation is not a convenient tool. | arxiv:nlin/0105059 |
binder - cumulant analysis of the critical point in the heavy - quark region of qcd is performed by monte - carlo simulations with the hopping - parameter expansion at $ n _ t = 6 $. we extend our previous analysis at $ n _ t = 4 $ to finer lattices and perform high - precision analyses on large spatial volumes up to the aspect ratio $ lt = n _ s / n _ t = 18 $. higher order terms in the hopping - parameter expansion are incorporated effectively up to 14th order. the numerical results show that the violation of the finite - size scaling becomes more prominent on the finer lattice at a given aspect ratio. | arxiv:2407.09156 |
tidal streams of the sagittarius dwarf spheroidal galaxy ( sgr ) may be showering dark matter onto the solar system and contributing approx ( 0. 3 - - 23 ) % of the local density of our galactic halo. if the sagittarius galaxy contains wimp dark matter, the extra contribution from the stream gives rise to a step - like feature in the energy recoil spectrum in direct dark matter detection. for our best estimate of stream velocity ( 300 km / sec ) and direction ( the plane containing the sgr dwarf and its debris ), the count rate is maximum on june 28 and minimum on december 27 ( for most recoil energies ), and the location of the step oscillates yearly with a phase opposite to that of the count rate. in the cdms experiment, for 60 gev wimps, the location of the step oscillates between 35 and 42 kev, and for the most favorable stream density, the stream should be detectable at the 11 sigma level in four years of data with 10 kev energy bins. planned large detectors like xenon, cryoarray and the directional detector drift may also be able to identify the sgr stream. | arxiv:astro-ph/0309279 |
we have performed high - resolution powder x - ray diffraction measurements on a sample of $ ^ { 242 } $ pucoga $ _ { 5 } $, the heavy - fermion superconductor with the highest critical temperature $ t _ { c } $ = 18. 7 k. the results show that the tetragonal symmetry of its crystallographic lattice is preserved down to 2 k. marginal evidence is obtained for an anomalous behaviour below $ t _ { c } $ of the $ a $ and $ c $ lattice parameters. the observed thermal expansion is isotropic down to 150 k, and becomes anisotropic for lower temperatures. this gives a $ c / a $ ratio that decreases with increasing temperature to become almost constant above $ \ sim $ 150 k. the volume thermal expansion coefficient $ \ alpha _ { v } $ has a jump at $ t _ { c } $, a factor $ \ sim $ 20 larger than the change predicted by the ehrenfest relation for a second order phase transition. the volume expansion deviates from the curve expected for the conventional anharmonic behaviour described by a simple gr \ " { u } neisen - einstein model. the observed differences are about ten times larger than the statistical error bars but are too small to be taken as an indication for the proximity of the system to a valence instability that is avoided by the superconducting state. | arxiv:1703.08984 |
in the big data era, graph computing is widely used to exploit the hidden value in real - world graphs in various scenarios such as social networks, knowledge graphs, web searching, and recommendation systems. however, the random memory accesses result in inefficient use of cache and the irregular degree distribution leads to substantial load imbalance. breadth - first search ( bfs ) is frequently utilized as a kernel for many important and complex graph algorithms. in this paper, we describe a preprocessing approach using reverse cuthill - mckee ( rcm ) algorithm to improve data locality and demonstrate how to achieve an efficient load balancing for bfs. computations on rcm - reordered graph data are also accelerated with simd executions. we evaluate the performance of the graph preprocessing approach on kronecker graphs of the graph500 benchmark and real - world graphs. our bfs implementation on rcm - reordered graph data achieves 326. 48 mteps / w ( mega teps per watt ) on an armv8 system, ranking 2nd on the green graph500 list in june 2020 ( the 1st rank uses gpu acceleration ). | arxiv:2012.10026 |
occurring in a network, based on the historic presence or absence of the edge in a sample of networks. interest in networks exploded around 2000, following new discoveries that offered novel mathematical framework to describe different network topologies, leading to the term ' network science '. albert - laszlo barabasi and reka albert discovered the scale - free networks nature of many real networks, from the www to the cell. the scale - free property captures the fact that in real network hubs coexist with many small degree vertices, and the authors offered a dynamical model to explain the origin of this scale - free state. duncan watts and steven strogatz reconciled empirical data on networks with mathematical representation, describing the small - world network. = = network classification = = = = = deterministic network = = = the definition of deterministic network is defined compared with the definition of probabilistic network. in un - weighted deterministic networks, edges either exist or not, usually we use 0 to represent non - existence of an edge while 1 to represent existence of an edge. in weighted deterministic networks, the edge value represents the weight of each edge, for example, the strength level. = = = probabilistic network = = = in probabilistic networks, values behind each edge represent the likelihood of the existence of each edge. for example, if one edge has a value equals to 0. 9, we say the existence probability of this edge is 0. 9. = = network properties = = often, networks have certain attributes that can be calculated to analyze the properties & characteristics of the network. the behavior of these network properties often define network models and can be used to analyze how certain models contrast to each other. many of the definitions for other terms used in network science can be found in glossary of graph theory. = = = size = = = the size of a network can refer to the number of nodes n { \ displaystyle n } or, less commonly, the number of edges e { \ displaystyle e } which ( for connected graphs with no multi - edges ) can range from n − 1 { \ displaystyle n - 1 } ( a tree ) to e max { \ displaystyle e _ { \ max } } ( a complete graph ). in the case of a simple graph ( a network in which at most one ( undirected ) edge exists between each pair of vertices, and in which no vertices connect to themselves ), we have e max = ( n 2 ) | https://en.wikipedia.org/wiki/Network_science |
coherent radio emission with properties similar to planetary auroral signals has been reported from gj 1151, a quiescent, slow - rotating mid - m star, by the lofar two - metre ( 120 - 170 mhz ) sky survey ( lotss ). the observed { lofar } emission is fairly bright at 0. 89 mjy with 64 % circular polarization, and the emission characteristics are consistent with the interaction between an earth - sized planet with an orbital period of 1 - 5 days and the magnetic field of the host star. however, no short - period planet has been detected around gj 1151. to confirm the reported radio emission caused by the putative planet around gj 1151 and to investigate the nature of this emission, we carried out ugmrt observations of gj 1151 at 150, 218, and 400 mhz over 33 hours across ten epochs. no emission was detected at any frequency. while at 150 mhz and 218 mhz, non - detection could be due to the low sensitivity of our observations, at 400 mhz, the rms sensitivities achieved were sufficient to detect the emission observed with lofar at $ \ sim $ 20 $ \ sigma $ level. our findings suggest that the radio emission is highly time - variable, likely influenced by the star - planet system ' s phase and the host star ' s magnetic field. additional observations below 170 mhz, at more frequent epochs ( as the periodicity of the emission is unknown ), especially during periods of high stellar magnetic field strength, are needed to confirm the emission. | arxiv:2409.18507 |
we propose mirror descent optimal transport ( mdot ), a novel method for solving discrete optimal transport ( ot ) problems with high precision, by unifying temperature annealing in entropic - regularized ot ( eot ) with mirror descent techniques. in this framework, temperature annealing produces a sequence of eot dual problems, whose solution gradually gets closer to the solution of the original ot problem. we solve each problem efficiently using a gpu - parallel nonlinear conjugate gradients algorithm ( pncg ) that outperforms traditional sinkhorn iterations under weak regularization. moreover, our investigation also reveals that the theoretical convergence rate of sinkhorn iterations can exceed existing non - asymptotic bounds when its stopping criterion is tuned in a manner analogous to mdot. our comprehensive ablation studies of mdot - pncg affirm its robustness across a wide range of algorithmic parameters. benchmarking on 24 problem sets of size $ n = 4096 $ in a gpu environment demonstrate that our method attains high - precision, feasible solutions significantly faster than a representative set of existing ot solvers ( including accelerated gradient methods and advanced sinkhorn variants ) in both wall - clock time and number of operations. empirical convergence rates range between $ o ( n ^ 2 \ varepsilon ^ { - 1 / 4 } ) $ and $ o ( n ^ 2 \ varepsilon ^ { - 1 } ) $, where $ \ varepsilon $ is the optimality gap. for problem sizes up to $ { n = 16, 384 } $, the empirical runtime scales as $ \ widetilde { o } ( n ^ 2 ) $ for moderate precision and as $ \ widetilde { o } ( n ^ { 5 / 2 } ) $ at worst for high precision. these findings establish mdot - pncg as a compelling alternative to current ot solvers, particularly in challenging weak - regularization regimes. | arxiv:2307.08507 |
the electrical conduction properties of g4 - dna are investigated using a hybrid approach, which combines electronic structure calculations, molecular dynamics ( md ) simulations, and the formulation of an effective tight - binding model hamiltonian. charge transport is studied by computing transmission functions along the md trajectories. though g4 - dna is structurally more stable than double - stranded dna ( dsdna ), our results strongly suggest that the potential improvement of the electrical transport properties in the former is not necessarily related to an increased stability, but rather to the fact that g4 is able to explore in its conformational space a larger number of charge - transfer active conformations. this in turn is a result of the non - negligible interstrand matrix elements, which allow for additional charge transport pathways. the higher structural stability of g4 can however play an important role once the molecules are contacted by electrodes. in this case, g4 may experience weaker structural distortions than dsdna and thus preserve to a higher degree its conduction properties. | arxiv:1010.5199 |
based on the result of classification in our previous work, we exhaustively investigate yukawa sector of $ u ( 8 ) $ model on magnetized orbifolds $ t ^ { 2 } / z _ { 2 } $, $ t ^ { 2 } / z _ { 3 } $, $ t ^ { 2 } / z _ { 4 } $ and $ t ^ { 2 } / z _ { 6 } $ by evaluating ratios of the mass eigenvalues of the three states in all the possible configurations with one and two higgs pairs where three generations are realized in fermions. because of smearing effect via kinetic mixing, one can realize a hierarchy such as $ 10 ^ { - 2 } $ - $ 10 ^ { - 3 } $, but it is very difficult to achieve the mass ratio between the up and top quarks ( $ m _ { \ text { up } } / m _ { \ text { top } } \ sim 10 ^ { - 5 } $ ) on the complicated magnetized orbifolds $ t ^ { 2 } / z _ { n } \, ( n = 3, 4, 6 ) $. | arxiv:1605.00140 |
in one or more of these kinds of structures, it is invariably accompanied by an increase or decrease of energy of the substances involved. some energy is transferred between the surroundings and the reactants of the reaction in the form of heat or light ; thus the products of a reaction may have more or less energy than the reactants. a reaction is said to be exergonic if the final state is lower on the energy scale than the initial state ; in the case of endergonic reactions the situation is the reverse. a reaction is said to be exothermic if the reaction releases heat to the surroundings ; in the case of endothermic reactions, the reaction absorbs heat from the surroundings. chemical reactions are invariably not possible unless the reactants surmount an energy barrier known as the activation energy. the speed of a chemical reaction ( at given temperature t ) is related to the activation energy e, by the boltzmann ' s population factor e − e / k t { \ displaystyle e ^ { - e / kt } } – that is the probability of a molecule to have energy greater than or equal to e at the given temperature t. this exponential dependence of a reaction rate on temperature is known as the arrhenius equation. the activation energy necessary for a chemical reaction to occur can be in the form of heat, light, electricity or mechanical force in the form of ultrasound. a related concept free energy, which also incorporates entropy considerations, is a very useful means for predicting the feasibility of a reaction and determining the state of equilibrium of a chemical reaction, in chemical thermodynamics. a reaction is feasible only if the total change in the gibbs free energy is negative, δ g ≤ 0 { \ displaystyle \ delta g \ leq 0 \, } ; if it is equal to zero the chemical reaction is said to be at equilibrium. there exist only limited possible states of energy for electrons, atoms and molecules. these are determined by the rules of quantum mechanics, which require quantization of energy of a bound system. the atoms / molecules in a higher energy state are said to be excited. the molecules / atoms of substance in an excited energy state are often much more reactive ; that is, more amenable to chemical reactions. the phase of a substance is invariably determined by its energy and the energy of its surroundings. when the intermolecular forces of a substance are such that the energy of the surroundings is not sufficient to overcome them, it occurs in a more ordered phase like liquid | https://en.wikipedia.org/wiki/Chemistry |
we generalize the derivation of the wallis formula for $ \ pi $ from a variational computation of the spectrum of the hydrogen atom. we obtain infinite product formulas for certain combinations of gamma functions, which include irrational numbers such as $ \ sqrt 2 $ as well as some nested radicals. we also derive euler ' s reflection formula for reciprocals of positive even integers. we show that bohr ' s correspondence principle allows us to derive our product formulas and the reflection formula without the need for the limit definition of the gamma function. | arxiv:2103.07896 |
man - at - the - end ( mate ) attackers have full control over the system on which the attacked software runs, and try to break the confidentiality or integrity of assets embedded in the software. both companies and malware authors want to prevent such attacks. this has driven an arms race between attackers and defenders, resulting in a plethora of different protection and analysis methods. however, it remains difficult to measure the strength of protections because mate attackers can reach their goals in many different ways and a universally accepted evaluation methodology does not exist. this survey systematically reviews the evaluation methodologies of papers on obfuscation, a major class of protections against mate attacks. for 571 papers, we collected 113 aspects of their evaluation methodologies, ranging from sample set types and sizes, over sample treatment, to performed measurements. we provide detailed insights into how the academic state of the art evaluates both the protections and analyses thereon. in summary, there is a clear need for better evaluation methodologies. we identify nine challenges for software protection evaluations, which represent threats to the validity, reproducibility, and interpretation of research results in the context of mate attacks and formulate a number of concrete recommendations for improving the evaluations reported in future research papers. | arxiv:2307.07300 |
hyperspectral imaging ( hsi ) has become a key technology for non - invasive quality evaluation in various fields, offering detailed insights through spatial and spectral data. despite its efficacy, the complexity and high cost of hsi systems have hindered their widespread adoption. this study addressed these challenges by exploring deep learning - based hyperspectral image reconstruction from rgb ( red, green, blue ) images, particularly for agricultural products. specifically, different hyperspectral reconstruction algorithms, such as hyperspectral convolutional neural network - dense ( hscnn - d ), high - resolution network ( hrnet ), and multi - scale transformer plus plus ( mst + + ), were compared to assess the dry matter content of sweet potatoes. among the tested reconstruction methods, hrnet demonstrated superior performance, achieving the lowest mean relative absolute error ( mrae ) of 0. 07, root mean square error ( rmse ) of 0. 03, and the highest peak signal - to - noise ratio ( psnr ) of 32. 28 decibels ( db ). some key features were selected using the genetic algorithm ( ga ), and their importance was interpreted using explainable artificial intelligence ( xai ). partial least squares regression ( plsr ) models were developed using the rgb, reconstructed, and ground truth ( gt ) data. the visual and spectra quality of these reconstructed methods was compared with gt data, and predicted maps were generated. the results revealed the prospect of deep learning - based hyperspectral image reconstruction as a cost - effective and efficient quality assessment tool for agricultural and biological applications. | arxiv:2405.13331 |
in this paper we introduce a natural generalization of the well - known problems cluster editing and bicluster editing, whose parameterized versions have been intensively investigated in the recent literature. the generalized problem, called mixed cluster editing or $ { \ cal m } $ - cluster editing, is formulated as follows. let $ { \ cal m } $ be a family of graphs. given a graph $ g $ and a nonnegative integer $ k $, transform $ g $, through a sequence of at most $ k $ edge editions, into a target graph $ g ' $ with the following property : $ g ' $ is a vertex - disjoint union of graphs $ g _ 1, g _ 2, \ ldots $ such that every $ g _ i $ is a member of $ { \ cal m } $. the graph $ g ' $ is called a mixed cluster graph or $ { \ cal m } $ - cluster graph. let $ { \ cal k } $ denote the family of complete graphs, $ { \ cal kl } $ the family of complete $ l $ - partite graphs ( $ l \ geq 2 $ ), and $ \ l = { \ cal k } \ cup { \ cal kl } $. in this work we focus on the case $ { \ cal m } = { \ cal l } $. using modular decomposition techniques previously applied to cluster / bicluster editing, we present a linear - time algorithm to construct a problem kernel for the parameterized version of $ { \ cal l } $ - cluster editing. keywords : bicluster graphs, cluster graphs, edge edition problems, edge modification problems, fixed - parameter tractability, np - complete problems. | arxiv:1506.00944 |
in this work, we introduce the resilient projected push - pull ( rp3 ) algorithm designed for distributed optimization in multi - agent cyber - physical systems with directed communication graphs and the presence of malicious agents. our algorithm leverages stochastic inter - agent trust values and gradient tracking to achieve geometric convergence rates in expectation even in adversarial environments. we introduce growing constraint sets to limit the impact of the malicious agents without compromising the geometric convergence rate of the algorithm. we prove that rp3 converges to the nominal optimal solution almost surely and in the $ r $ - th mean for any $ r \ geq 1 $, provided the step sizes are sufficiently small and the constraint sets are appropriately chosen. we validate our approach with numerical studies on average consensus and multi - robot target tracking problems, demonstrating that rp3 effectively mitigates the impact of malicious agents and achieves the desired geometric convergence. | arxiv:2407.06541 |
we prove that, for an enriques surface in odd characteristic, the automorphism group is finitely generated and it acts on the effective nef cone with a rational polyhedral fundamental domain. we also construct a smooth projective surface in odd characteristic which is birational to an enriques surface and whose automorphism group is discrete but not finitely generated. | arxiv:1908.07928 |
one typical assumption in inverse reinforcement learning ( irl ) is that human experts act to optimize the expected utility of a stochastic cost with a fixed distribution. this assumption deviates from actual human behaviors under ambiguity. risk - sensitive inverse reinforcement learning ( rs - irl ) bridges such gap by assuming that humans act according to a random cost with respect to a set of subjectively distorted distributions instead of a fixed one. such assumption provides the additional flexibility to model human ' s risk preferences, represented by a risk envelope, in safe - critical tasks. however, like other learning from demonstration techniques, rs - irl could also suffer inefficient learning due to redundant demonstrations. inspired by the concept of active learning, this research derives a probabilistic disturbance sampling scheme to enable an rs - irl agent to query expert support that is likely to expose unrevealed boundaries of the expert ' s risk envelope. experimental results confirm that our approach accelerates the convergence of rs - irl algorithms with lower variance while still guaranteeing unbiased convergence. | arxiv:1909.07843 |
we present a radiology - specific multimodal model for the task for generating radiological reports from chest x - rays ( cxrs ). our work builds on the idea that large language model ( s ) can be equipped with multimodal capabilities through alignment with pre - trained vision encoders. on natural images, this has been shown to allow multimodal models to gain image understanding and description capabilities. our proposed model ( maira - 1 ) leverages a cxr - specific image encoder in conjunction with a fine - tuned large language model based on vicuna - 7b, and text - based data augmentation, to produce reports with state - of - the - art quality. in particular, maira - 1 significantly improves on the radiologist - aligned radcliq metric and across all lexical metrics considered. manual review of model outputs demonstrates promising fluency and accuracy of generated reports while uncovering failure modes not captured by existing evaluation practices. more information and resources can be found on the project website : https : / / aka. ms / maira. | arxiv:2311.13668 |
dwarf spheroidal galaxies are excellent systems to probe the nature of fermionic dark matter due to their high observed dark matter phase - space density. in this work, we review, revise and improve upon previous phase - space considerations to obtain lower bounds on the mass of fermionic dark matter particles. the refinement in the results compared to previous works is realised particularly due to a significantly improved jeans analysis of the galaxies. we discuss two methods to obtain phase - space bounds on the dark matter mass, one model - independent bound based on pauli ' s principle, and the other derived from an application of liouville ' s theorem. as benchmark examples for the latter case, we derive constraints for thermally decoupled particles and ( non - ) resonantly produced sterile neutrinos. using the pauli principle, we report a model - independent lower bound of $ m \ geq 0. 18 \, \ mathrm { kev } $ at 68 % cl and $ m \ geq 0. 13 \, \ mathrm { kev } $ at 95 % cl. for relativistically decoupled thermal relics, this bound is strengthened to $ m \ geq 0. 59 \, \ mathrm { kev } $ at 68 % cl and $ m \ geq 0. 41 \, \ mathrm { kev } $ at 95 % cl, whilst for non - resonantly produced sterile neutrinos the constraint is $ m \ geq 2. 80 \, \ mathrm { kev } $ at 68 % cl and $ m \ geq 1. 74 \, \ mathrm { kev } $ at 95 % cl. finally, the phase - space bounds on resonantly produced sterile neutrinos are compared with complementary limits from x - ray, lyman - $ \ alpha $ and big bang nucleosynthesis observations. | arxiv:2010.03572 |
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