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scanning ), treatment ( like the dialysis machine, defibrillator, pacemaker, and a wide array of new pharmaceutical drugs ), and research ( like interferon cloning and dna microarrays ). complex manufacturing and construction techniques and organizations are needed to make and maintain more modern technologies, and entire industries have arisen to develop succeeding generations of increasingly more complex tools. modern technology increasingly relies on training and education – their designers, builders, maintainers, and users often require sophisticated general and specific training. moreover, these technologies have become so complex that entire fields have developed to support them, including engineering, medicine, and computer science ; and other fields have become more complex, such as construction, transportation, and architecture. = = impact = = technological change is the largest cause of long - term economic growth. throughout human history, energy production was the main constraint on economic development, and new technologies allowed humans to significantly increase the amount of available energy. first came fire, which made edible a wider variety of foods, and made it less physically demanding to digest them. fire also enabled smelting, and the use of tin, copper, and iron tools, used for hunting or tradesmanship. then came the agricultural revolution : humans no longer needed to hunt or gather to survive, and began to settle in towns and cities, forming more complex societies, with militaries and more organized forms of religion. technologies have contributed to human welfare through increased prosperity, improved comfort and quality of life, and medical progress, but they can also disrupt existing social hierarchies, cause pollution, and harm individuals or groups. recent years have brought about a rise in social media ' s cultural prominence, with potential repercussions on democracy, and economic and social life. early on, the internet was seen as a " liberation technology " that would democratize knowledge, improve access to education, and promote democracy. modern research has turned to investigate the internet ' s downsides, including disinformation, polarization, hate speech, and propaganda. since the 1970s, technology ' s impact on the environment has been criticized, leading to a surge in investment in solar, wind, and other forms of clean energy. = = = social = = = = = = = jobs = = = = since the invention of the wheel, technologies have helped increase humans ' economic output. past automation has both substituted and complemented labor ; machines replaced humans at some lower - paying jobs ( for example in agriculture ), but this was compensated by the creation
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https://en.wikipedia.org/wiki/Technology
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decision - making for self - adaptation approaches need to address different challenges, including the quantification of the uncertainty of events that cannot be foreseen in advance and their effects, and dealing with conflicting objectives that inherently involve multi - objective decision making ( e. g., avoiding costs vs. providing reliable service ). to enable researchers to evaluate and compare decision - making techniques for self - adaptation, we present the rdmsim exemplar. rdmsim enables researchers to evaluate and compare techniques for decision - making under environmental uncertainty that support self - adaptation. the focus of the exemplar is on the domain problem related to remote data mirroring, which gives opportunity to face the challenges described above. rdmsim provides probe and effector components for easy integration with external adaptation managers, which are associated with decision - making techniques and based on the mape - k loop. specifically, the paper presents ( i ) rdmsim, a simulator for real - world experimentation, ( ii ) a set of realistic simulation scenarios that can be used for experimentation and comparison purposes, ( iii ) data for the sake of comparison.
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arxiv:2105.01978
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stochastic gradient descent ( sgd ) is an inherently sequential training algorithm - - computing the gradient at batch $ i $ depends on the model parameters learned from batch $ i - 1 $. prior approaches that break this dependence do not honor them ( e. g., sum the gradients for each batch, which is not what sequential sgd would do ) and thus potentially suffer from poor convergence. this paper introduces a novel method to combine gradients called adasum ( for adaptive sum ) that converges faster than prior work. adasum is easy to implement, almost as efficient as simply summing gradients, and is integrated into the open - source toolkit horovod. this paper first provides a formal justification for adasum and then empirically demonstrates adasum is more accurate than prior gradient accumulation methods. it then introduces a series of case - studies to show adasum works with multiple frameworks, ( tensorflow and pytorch ), scales multiple optimizers ( momentum - sgd, adam, and lamb ) to larger batch - sizes while still giving good downstream accuracy. finally, it proves that adasum converges. to summarize, adasum scales momentum - sgd on the mlperf resnet50 benchmark to 64k examples before communication ( no mlperf v0. 5 entry converged with more than 16k ), the adam optimizer to 64k examples before communication on bert - large ( prior work showed adam stopped scaling at 16k ), and the lamb optimizer to 128k before communication on bert - large ( prior work used 64k ), all while maintaining downstream accuracy metrics. finally, if a user does not need to scale, we show lamb with adasum on bert - large converges in 30 % fewer steps than the baseline.
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arxiv:2006.02924
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we determine the surface tension of aqueous electrolyte solutions in contact with non - polar dielectric media using a thermomechanical approach, which involves deriving the stress tensor from the thermodynamic potential of an inhomogeneous fluid. to obtain the surface tension, we calculate both the normal and tangential pressures using the components of the stress tensor, recently derived by us [ y. a. budkov and p. e. brandyshev, the journal of chemical physics 159 ( 2023 ) ] within the framework of wang ' s variational field theory. using this approach, we derive an analytical expression for the surface tension in the linear approximation. at low ionic concentrations, this expression represents the classical onsager - samaras limiting law. by utilizing only one fitting parameter, which is related to the affinity of anions to the dielectric boundary, we can approximate various experimental data regarding the surface tension of aqueous electrolyte solutions. this approximation applies to both the solution - air and solution - dodecane interfaces, covering a wide range of electrolyte concentrations.
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arxiv:2312.10753
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the instanton contribution to the quark distribution functions in the nucleon is estimated. it is shown, that taking into account the instanton induced interaction between quarks allows to explain the anomalous violation of the ellis - jaffe and gottfried sum rules. the spin - dependent structure functions $ g _ 1 ^ p ( x ) $, $ g _ 1 ^ n ( x ) $, $ g _ 1 ^ d ( x ) $ are calculated in the framework of the instanton model of the qcd vacuum.
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arxiv:hep-ph/9511299
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modeling expressive cross - modal interactions seems crucial in multimodal tasks, such as visual question answering. however, sometimes high - performing black - box algorithms turn out to be mostly exploiting unimodal signals in the data. we propose a new diagnostic tool, empirical multimodally - additive function projection ( emap ), for isolating whether or not cross - modal interactions improve performance for a given model on a given task. this function projection modifies model predictions so that cross - modal interactions are eliminated, isolating the additive, unimodal structure. for seven image + text classification tasks ( on each of which we set new state - of - the - art benchmarks ), we find that, in many cases, removing cross - modal interactions results in little to no performance degradation. surprisingly, this holds even when expressive models, with capacity to consider interactions, otherwise outperform less expressive models ; thus, performance improvements, even when present, often cannot be attributed to consideration of cross - modal feature interactions. we hence recommend that researchers in multimodal machine learning report the performance not only of unimodal baselines, but also the emap of their best - performing model.
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arxiv:2010.06572
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this study investigates the role of spatial segregation, prompted by competition avoidance, as a key mechanism for emergent coexistence within microbial communities. recognizing these communities as complex adaptive systems, we challenge the sufficiency of mean - field pairwise interaction models and consider the impact of spatial dynamics. we developed an individual - based spatial simulation depicting bacterial movement through a pattern of random walks influenced by competition avoidance, leading to the formation of spatially segregated clusters. this model was integrated with a lotka - volterra metapopulation framework focused on competitive interactions. our findings reveal that spatial segregation combined with low diffusion rates and high compositional heterogeneity among patches can lead to emergent coexistence in microbial communities. this reveals a novel mechanism underpinning the formation of stable, coexisting microbe clusters, which is nonetheless incapable of promoting coexistence in the case of isolated pairs of species. this study underscores the importance of considering spatial factors in understanding the dynamics of microbial ecosystems.
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arxiv:2401.17048
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following the success of machine vision systems for on - line automated quality control and inspection processes, an object recognition solution is presented in this work for two different specific applications, i. e., the detection of quality control items in surgery toolboxes prepared for sterilizing in a hospital, as well as the detection of defects in vessel hulls to prevent potential structural failures. the solution has two stages. first, a feature pyramid architecture based on single shot multibox detector ( ssd ) is used to improve the detection performance, and a statistical analysis based on ground truth is employed to select parameters of a range of default boxes. second, a lightweight neural network is exploited to achieve oriented detection results using a regression method. the first stage of the proposed method is capable of detecting the small targets considered in the two scenarios. in the second stage, despite the simplicity, it is efficient to detect elongated targets while maintaining high running efficiency.
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arxiv:2101.07383
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based on the accurately calibrated interaction fsugold, we show that including isovector scalar $ \ delta $ meson and its coupling to isoscalar scalar $ \ sigma $ meson in the relativistic mean field ( rmf ) model can soften the symmetry energy $ e _ { \ rm { sym } } ( n ) $ at intermediate densities while stiffen the $ e _ { \ rm { sym } } ( n ) $ at high densities. we find this new rmf model can be simultaneously compatible with ( 1 ) the constraints on the equation of state of symmetric nuclear matter at suprasaturation densities from flow data in heavy - ion collisions, ( 2 ) the neutron skin thickness of $ ^ { 208 } $ pb from the prex - ii experiment, ( 3 ) the largest mass of neutron star ( ns ) reported so far from psr j0740 + 6620, ( 4 ) the limit of $ \ lambda _ { 1. 4 } \ leq580 $ for the dimensionless tidal deformability of the canonical 1. 4 $ m _ { \ odot } $ ns from the gravitational wave signal gw170817, ( 5 ) the mass - radius relation of psr j0030 + 0451 and psr j0740 + 6620 measured by nicer, and thus remove the tension between prex - ii and gw170817 observed in the conventional rmf model.
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arxiv:2202.08705
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fault - tolerant consensus has been studied extensively in the literature, because it is one of the most important distributed primitives and has wide applications in practice. this paper surveys important results on fault - tolerant consensus in message - passing networks, and the focus is on results from the past decade. particularly, we categorize the results into two groups : new problem formulations and practical applications. in the first part, we discuss new ways to define the consensus problem, which includes larger input domains, link fault models, different network models... etc, and briefly discuss the important techniques. in the second part, we focus on crash fault - tolerant ( cft ) systems that use paxos or raft, and byzantine fault - tolerant ( bft ) systems. we also discuss bitcoin, which can be related to solving byzantine consensus in anonymous systems, and compare bitcoin with bft systems and byzantine consensus.
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arxiv:1608.07923
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in a broad class of theories, the accumulation of ultralight dark matter ( uldm ) with particles of mass $ 10 ^ { - 22 } ~ \ textrm { ev } < m _ { \ phi } < 1 ~ \ textrm { ev } $ leads the to formation of long - lived bound states known as boson stars. when the uldm exhibits self - interactions, prodigious bursts of energy carried by relativistic bosons are released from collapsing boson stars in bosenova explosions. we extensively explore the potential reach of terrestrial and space - based experiments for detecting transient signatures of emitted relativistic bursts of scalar particles, including uldm coupled to photons, electrons, and gluons, capturing a wide range of motivated theories. for the scenario of relaxion uldm, we demonstrate that upcoming experiments and technology such as nuclear clocks as well as space - based interferometers will be able to sensitively probe orders of magnitude in the uldm coupling - mass parameter space, challenging to study otherwise, by detecting signatures of transient bosenova events. our analysis can be readily extended to different scenarios of relativistic scalar particle emission.
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arxiv:2306.16468
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in 1822, cauchy presented the idea of traction vector that contains both the normal and tangential components of the internal surface forces per unit area and gave the tetrahedron argument to prove the existence of stress tensor. these great achievements form the main part of the foundation of continuum mechanics. for about two centuries, some versions of tetrahedron argument and a few other proofs of the existence of stress tensor are presented in every text on continuum mechanics, fluid mechanics, and the relevant subjects. in this article, we show the birth, importance, and location of these cauchy ' s achievements, then by presenting the formal tetrahedron argument in detail, for the first time, we extract some fundamental challenges. these conceptual challenges are related to the result of applying the conservation of linear momentum to any mass element, the order of magnitude of the surface and volume terms, the definition of traction vectors on the surfaces that pass through the same point, the approximate processes in the derivation of stress tensor, and some others. in a comprehensive review, we present the different tetrahedron arguments and the proofs of the existence of stress tensor, discuss the challenges in each one, and classify them in two general approaches. in the first approach that is followed in most texts, the traction vectors do not exactly define on the surfaces that pass through the same point, so most of the challenges hold. but in the second approach, the traction vectors are defined on the surfaces that pass exactly through the same point, therefore some of the relevant challenges are removed. we also study the improved works of hamel and backus, and indicate that the original work of backus removes most of the challenges. this article shows that the foundation of continuum mechanics is not a finished subject and there are still some fundamental challenges.
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arxiv:1706.08518
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we introduce a scalable bayesian preference learning method for identifying convincing arguments in the absence of gold - standard rat - ings or rankings. in contrast to previous work, we avoid the need for separate methods to perform quality control on training data, predict rankings and perform pairwise classification. bayesian approaches are an effective solution when faced with sparse or noisy training data, but have not previously been used to identify convincing arguments. one issue is scalability, which we address by developing a stochastic variational inference method for gaussian process ( gp ) preference learning. we show how our method can be applied to predict argument convincingness from crowdsourced data, outperforming the previous state - of - the - art, particularly when trained with small amounts of unreliable data. we demonstrate how the bayesian approach enables more effective active learning, thereby reducing the amount of data required to identify convincing arguments for new users and domains. while word embeddings are principally used with neural networks, our results show that word embeddings in combination with linguistic features also benefit gps when predicting argument convincingness.
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arxiv:1806.02418
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uranus has three known co - orbitals : 83982 crantor ( 2002 go9 ), 2010 eu65 and 2011 qf99. here, we perform a comparative analysis of the orbital evolution of these transient co - orbitals to understand better how they got captured in the first place and what makes them dynamically unstable. we also look for additional temporary uranian co - orbital candidates among known objects. our n - body simulations show that the long - term stability of 2011 qf99 is controlled by jupiter and neptune ; it briefly enters the 1 : 7 mean motion resonance with jupiter and the 2 : 1 with neptune before becoming a trojan and prior to leaving its tadpole orbit. during these ephemeral two - body mean motion resonance episodes, apsidal corotation resonances are also observed. for known co - orbitals, saturn is the current source of the main destabilizing force but this is not enough to eject a minor body from the 1 : 1 commensurability with uranus. these objects must enter mean motion resonances with jupiter and neptune in order to be captured or become passing centaurs. asteroid 2010 eu65, a probable visitor from the oort cloud, may have been stable for several myr due to its comparatively low eccentricity. in addition, we show that the orbital properties and discovery circumstances of known objects can be used to outline a practical strategy by which additional uranus ' co - orbitals may be found.
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arxiv:1404.2898
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it is demonstrated in the context of the simple one - dimensional example of a barrier in an infinite well, that highly complex behavior of the time evolution of a wave function is associated with the almost degeneracy of levels in the process of tunneling. degenerate conditions are obtained by shifting the position of the barrier. the complexity strength depends on the number of almost degenerate levels which depend on geometrical symmetry. the presence of complex behavior is studied to establish correlation with spectral degeneracy.
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arxiv:cond-mat/9604130
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a relativistic light front treatment of nuclei is developed by performing light front quantization for a chiral lagrangian. the energy momentum tensor and the appropriate hamiltonian are obtained. three illustrations of the formalism are made. ( 1 ) pion - nucleon scattering at tree level is shown to reproduce soft pion theorems. ( 2 ) the one boson exchange treatment of nucleon - nucleon scattering is developed and shown ( by comparison with previous results of the equal time formulation ) to lead to a reasonable description of nucleon - nucleon phase shifts. ( 3 ) the mean field approximation is applied to infinite nuclear matter, and the plus momentum distributions of that system are studied. the mesons are found to carry a significant fraction of the plus momentum, but are inaccessible to experiments.
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arxiv:nucl-th/9706028
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this paper analyzes the convergence of fixed - point iterations of the form u = f ( u ) and the properties of the inverse of the related pentadiagonal matrices, associated with the fourth - order nonlinear beam equation. this nonlinear problem is discretized using the finite difference method with the clamped - free and clamped - clamped boundary conditions in the one dimension. explicit formulas for the inverse of the matrices and norms of the inverse are derived. in iterative process, the direct computation of inverse matrix allows to achieve an efficiency. numerical results were provided.
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arxiv:2104.02280
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we derive several tools for classifying tensor ideals in monoidal categories. we use these results to classify tensor ideals in deligne ' s universal categories repo, repgl and repp. these results are then used to obtain new insight into the second fundamental theorem of invariant theory for the algebraic supergroups of types a, b, c, d, p. we also find short proofs for the classification of tensor ideals in reps and in the category of tilting modules for sl2 ( k ) with char ( k ) > 0 and for uq ( sl2 ) with q a root of unity. in general, for a simple lie algebra g of type ade, we show that the lattice of such tensor ideals for uq ( g ) corresponds to the lattice of submodules in a parabolic verma module for the corresponding affine kac - moody algebra.
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arxiv:1712.06248
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we present a new method for estimating the neural reflectance field ( nref ) of an object from a set of posed multi - view images under unknown lighting. nref represents 3d geometry and appearance of objects in a disentangled manner, and are hard to be estimated from images only. our method solves this problem by exploiting the neural radiance field ( nerf ) as a proxy representation, from which we perform further decomposition. a high - quality nerf decomposition relies on good geometry information extraction as well as good prior terms to properly resolve ambiguities between different components. to extract high - quality geometry information from radiance fields, we re - design a new ray - casting based method for surface point extraction. to efficiently compute and apply prior terms, we convert different prior terms into different type of filter operations on the surface extracted from radiance field. we then employ two type of auxiliary data structures, namely gaussian kd - tree and octree, to support fast querying of surface points and efficient computation of surface filters during training. based on this, we design a multi - stage decomposition optimization pipeline for estimating neural reflectance field from neural radiance fields. extensive experiments show our method outperforms other state - of - the - art methods on different data, and enable high - quality free - view relighting as well as material editing tasks.
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arxiv:2210.04217
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this review examines the roles of adaptation and synchronization in music performance, drawing on concepts from complex systems theory to understand the dynamic interactions between musicians, music, and listeners. adaptation is explored through how musicians adjust their cognitive, emotional, and motor systems across the stages of preparation, execution, and reception, while synchronization is emphasized as essential for aligning internal states, coordinating actions with other performers, and engaging with the audience. the review highlights the interdisciplinary nature of music performance research, integrating cognitive, motor, and emotional processes to enhance both individual and collective musical expression. it also addresses the psychological state of flow, which arises from synchronized neurocognitive mechanisms that optimize performance. additionally, the emotional synchronization facilitated by music is explored, emphasizing its role in both individual emotional coherence and social coordination within musical ensembles. finally, the review highlights recent findings on interpersonal and inter - brain synchronization, particularly in live music performances and improvisation, showing how synchronization fosters creativity, social cohesion, and a shared collective experience.
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arxiv:2504.03958
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grand unification possibilities in nambu - jona - lasinio - like models are studied. to address the problem of vector boson masses and nonrenormalizability of the theory, algebraic formalism encompassing the effective action, schwinger - keldysh path integral, and bogoliubov - parasiuk - hepp - zimmerman renormalization is constructed. a new njl - like model : the theory of current metric field interacting with fermions is proposed. bosonization in this model can produce massless vector bosons under certain conditions which makes it a candidate grand unified theory. both higgs and non - higgs effects can contribute to particle masses.
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arxiv:2503.24250
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game - theoretic concepts have been extensively studied in economics to provide insight into competitive behaviour and strategic decision making. as computing systems increasingly involve concurrently acting autonomous agents, game - theoretic approaches are becoming widespread in computer science as a faithful modelling abstraction. these techniques can be used to reason about the competitive or collaborative behaviour of multiple rational agents with distinct goals or objectives. this paper provides an overview of recent advances in developing a modelling, verification and strategy synthesis framework for concurrent stochastic games implemented in the probabilistic model checker prism - games. this is based on a temporal logic that supports finite - and infinite - horizon temporal properties in both a zero - sum and nonzero - sum setting, the latter using nash and correlated equilibria with respect to two optimality criteria, social welfare and social fairness. we summarise the key concepts, logics and algorithms and the currently available tool support. future challenges and recent progress in adapting the framework and algorithmic solutions to continuous environments and neural networks are also outlined.
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arxiv:2206.15148
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a proof of convergence is given for semi - and full discretizations of mean curvature flow of closed two - dimensional surfaces. the numerical method proposed and studied here combines evolving finite elements, whose nodes determine the discrete surface like in dziuk ' s method, and linearly implicit backward difference formulae for time integration. the proposed method differs from dziuk ' s approach in that it discretizes huisken ' s evolution equations for the normal vector and mean curvature and uses these evolving geometric quantities in the velocity law projected to the finite element space. this numerical method admits a convergence analysis in the case of finite elements of polynomial degree at least two and backward difference formulae of orders two to five. the error analysis combines stability estimates and consistency estimates to yield optimal - order $ h ^ 1 $ - norm error bounds for the computed surface position, velocity, normal vector and mean curvature. the stability analysis is based on the matrix - - vector formulation of the finite element method and does not use geometric arguments. the geometry enters only into the consistency estimates. numerical experiments illustrate and complement the theoretical results.
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arxiv:1805.06667
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we develop a family of accelerated stochastic algorithms that minimize sums of convex functions. our algorithms improve upon the fastest running time for empirical risk minimization ( erm ), and in particular linear least - squares regression, across a wide range of problem settings. to achieve this, we establish a framework based on the classical proximal point algorithm. namely, we provide several algorithms that reduce the minimization of a strongly convex function to approximate minimizations of regularizations of the function. using these results, we accelerate recent fast stochastic algorithms in a black - box fashion. empirically, we demonstrate that the resulting algorithms exhibit notions of stability that are advantageous in practice. both in theory and in practice, the provided algorithms reap the computational benefits of adding a large strongly convex regularization term, without incurring a corresponding bias to the original problem.
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arxiv:1506.07512
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the thermal conductivity k of the iron - arsenide superconductor lifeas ( tc ~ 18k ) was measured in single crystals at temperatures down to t ~ 50mk and in magnetic fields up to h = 17t, very close to the upper critical field hc2 ~ 18t. for both directions of the heat current, parallel and perpendicular to the tetragonal c - axis, a negligible residual linear term k / t is found as t - > 0, revealing that there are no zero - energy quasiparticles in the superconducting state. the increase in k with magnetic field is the same for both current directions and it follows closely the dependence expected for an isotropic superconducting gap. there is no evidence of multi - band character, whereby the gap would be different on different fermi - surface sheets. these findings show that the superconducting gap in lifeas is isotropic in 3d, without nodes or deep minima anywhere on the fermi surface. comparison with other iron - pnictide superconductors suggests that a nodeless isotropic gap is a common feature at optimal doping ( maximal tc ).
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arxiv:1104.2209
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dictionaries are one of the oldest and most used linguistic resources. building them is a complex task that, to the best of our knowledge, has yet to be explored with generative large language models ( llms ). we introduce the " spanish built factual freectianary " ( spanish - bff ) as the first spanish ai - generated dictionary. this first - of - its - kind free dictionary uses gpt - 3. we also define future steps we aim to follow to improve this initial commitment to the field, such as more additional languages.
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arxiv:2302.12746
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due to the mirror symmetry breaking, chiral structures show fantastic electromagnetic ( em ) properties involving negative refraction, giant optical activity, and asymmetric transmission. aligned electric and magnetic dipoles excited in chiral structures contribute to extraordinary properties. however, the chiral structures that exhibit n - fold rotational symmetry show limited tuning capability. in this paper, we proposed a compact, light, and highly tunable anisotropic chiral structure to overcome this limitation and realize a linear - to - circular polarization conversion. the anisotropy is due to simultaneous excitations of two different pairs of aligned electric and magnetic dipoles. the 3d omega - like structure, etched on two sides of one pcb board and connected by metallic vias, achieves 60 % of linearto - circular conversion ( transmission ) efficiency at the operating frequency of 9. 2 ghz. the desired 90 - degree phase shift between the two orthogonal linear polarization components is not only from the finite - thickness dielectric substrate but also from the anisotropic chiral response slightly off the resonance. the work enables elegant and practical polarization control of em waves.
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arxiv:1608.08208
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we investigate correlation functions in a periodic box - ball system. for the second and the third nearest neighbor correlation functions, we give explicit formulae obtained by combinatorial methods. a recursion formula for a specific $ n $ - point functions is also presented.
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arxiv:1103.3929
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we report the identification of the optical counterpart of the x - ray transient xte j1550 - 564 described in two companion papers by sobczak et al ( 1999 ) and remillard et al ( 1999 ). we find that the optical source brightened by approximately 4 magnitudes over the quiescent counterpart seen at b ~ 22 on a serc survey plate, and then decayed by approximately 1. 5 magnitudes over the 7 week long observation period. there was an optical response to the large x - ray flare described by sobczak et al ( 1999 ), but it was much smaller and delayed by roughly 1 day.
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arxiv:astro-ph/9903398
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time resolved pump and probe acoustics and first - principles calculations were employed to assess elastic properties of the tbmno3 perovskite manganite having orthorhombic symmetry. measuring sound velocities of bulk longitudinal and shear acoustic waves propagating along at least two different directions in the high symmetry planes ( 100 ), ( 010 ) and ( 001 ), provided a powerful mean to selectively determine the six diagonal elastic constants c11 = 227 gpa, c22 = 349 gpa, c33 = 274 gpa, c44 = 71 gpa, c55 = 57 gpa, c66 = 62 gpa. among the three remaining off - diagonal ones, c23 = 103 gpa was determined with a bissectrice direction. density functional theory calculations with colinear spin - polarized provided complementary insights on their optical, elastic and magnetoelastic properties.
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arxiv:2109.15023
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turing award winner juris hartmanis introduced in 1959 lattices of subspaces of generalized partitions ( " partitions of type n " ; " geometries " if $ n = 2 $ ). hartmanis states it is " an unsolved problem whether there are any incomplete lattice homomorphisms in " lattices of subspaces of geometries. ( he continues, " [ i ] f so how can these geometries be characterized. " ) we give a positive answer to this question.
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arxiv:1510.06513
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we present anamodiff, a novel diffusion - based method for 2d motion analogies that is applied to raw, unannotated videos of articulated characters. our goal is to accurately transfer motions from a 2d driving video onto a source character, with its identity, in terms of appearance and natural movement, well preserved, even when there may be significant discrepancies between the source and driving characters in their part proportions and movement speed and styles. our diffusion model transfers the input motion via a latent optical flow ( lof ) network operating in a noised latent space, which is spatially aware, efficient to process compared to the original rgb videos, and artifact - resistant through the diffusion denoising process even amid dense movements. to accomplish both motion analogy and identity preservation, we train our denoising model in a feature - disentangled manner, operating at two noise levels. while identity - revealing features of the source are learned via conventional noise injection, motion features are learned from lof - warped videos by only injecting noise with large values, with the stipulation that motion properties involving pose and limbs are encoded by higher - level features. experiments demonstrate that our method achieves the best trade - off between motion analogy and identity preservation.
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arxiv:2402.03549
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binary systems with neutron stars and double degenerate systems are crucial objects to test current stellar evolution models and einstein ' s general relativity. in this study, we present angular momentum loss mechanism via gravitational radiation and magnetized stellar winds for some selected systems with a neutron star. we calculated and plotted their time scales for angular momentum loss. gravitational wave amplitudes of binary systems with a neutron star components are also estimated and their detectability with a gravitational wave detector ( lisa ) has been plotted.
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arxiv:1603.03905
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we study possible systematic effects on the values of the cosmological parameters measured through strong lensing analyses of the hff galaxy cluster macs j1149. 5 + 2223. we use the observed positions of a large set of spectroscopically selected multiple images, including those of supernova " refsdal " with their estimated time delays. starting from our reference model in a flat $ \ lambda $ cdm cosmology, published in grillo et al. ( 2018 ), we confirm the relevance of the longest measurable time delay, between sx and s1, and an approximately linear relation between its value and that of $ h _ { 0 } $. we perform true blind tests by considering a range of time delays around its original estimate of $ 345 \ pm 10 $ days, as an accurate measurement of this time delay was not known at the time of analysis and writing. we investigate separately the impact of a constant sheet of mass at the cluster redshift, of a power - law profile for the mass density of the cluster main halo and of some scatter in the cluster member scaling relations. remarkably, we find that these systematic effects do not introduce a significant bias on the inferred values of $ h _ { 0 } $ and $ \ omega _ { \ rm m } $ and that the statistical uncertainties dominate the total error budget : a 3 % uncertainty on the time delay of image sx translates into approximately 6 % and 40 % ( including both statistical and systematic $ 1 \ sigma $ ) uncertainties for $ h _ { 0 } $ and $ \ omega _ { \ rm m } $, respectively. furthermore, our model accurately reproduces the extended surface brightness distribution of the supernova host, covering more than $ 3 \ times 10 ^ { 4 } $ $ hst $ pixels. we also present the interesting possibility of measuring the value of the equation - of - state parameter $ w $ of the dark energy density, currently with a 30 % uncertainty. we conclude that time - delay cluster lenses have the potential to become soon an alternative and competitive cosmological probe.
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arxiv:2001.02232
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the standard model of particle physics is extended by adding a purely neutrinophilic dark sector. it is shown that theories which accommodate standard model neutrinos as dark radiation are resurrected. sterile neutrinos bridge the visible and the dark sector and can keep their mutual interactions effective even after the epoch of big bang nucleosythesis. this prolonged contact between dark matter and standard model neutrinos solves the well - known small - scale structure problems of the cosmological standard model. the dark sector presented in this work satisfies all experimental and observational constraints from particle physics and cosmology.
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arxiv:1710.09846
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we derive the wick calculus for test and generalized functionals of noncommutative white noise corresponding to $ q $ - deformed commutation relations with $ q \ in ( - 1, 1 ) $. we construct a gel ' fand triple centered at the $ q $ - deformed fock space in which both the test, nuclear space and its dual space are algebras with respect to the addition and the wick multiplication. furthermore, we prove a v \ r { a } ge - type inequality for the wick product on the dual space.
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arxiv:1608.00211
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based on well - grounded galactic neutron star populations formed from radio pulsar population syntheses of canonical pulsars ( cps ) and millisecond pulsars ( msps ), we use the latest fermi - lat catalog ( 4fgl - dr4 ) to investigate the implications of proposed $ \ gamma - $ ray luminosity models. using monte carlo techniques, we calculate the number of cps and msps that would comprise the sample of pulsar - like unidentified sources ( pluids ) in 4fgl - dr4. while radio beaming fractions were used to scale the sizes of the populations, when forming the mock 4fgl - dr4 samples, we make the simplifying assumption that all $ \ gamma - $ ray pulsars are beaming towards the earth. we then explore the observable outcomes of seven different $ \ gamma - $ ray luminosity models. four of the models provide a good match to the observed number of pluids, while three others significantly over - predict the number of pluids. for these latter models, either the average beaming fraction of $ \ gamma - $ ray pulsars is more like 25 - - 50 \ %, or a revision in the luminosity scaling is required. most of the radio detectable msps that our models predict as part of the pluids within 4fgl - dr4 are, unsurprisingly, fainter than the currently observed sample and at larger dispersion measures. for cps, in spite of an excellent match to the observed radio population, none of the $ \ gamma - $ ray models we investigated could replicate the observed sample of 150 $ \ gamma - $ ray cps. further work is required to understand this discrepancy. for both msps and cps, we provide encouraging forecasts for targeted radio searches of pluids from 4fgl - dr4 to elucidate the issues raised in this study.
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arxiv:2504.02677
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we propose accelerated versions of the operator sinkhorn iteration for operator scaling using successive overrelaxation. we analyze the local convergence rates of these accelerated methods via linearization, which allows us to determine the asymptotically optimal relaxation parameter based on young ' s sor theorem. using the hilbert metric on positive definite cones, we also obtain a global convergence result for a geodesic version of overrelaxation in a specific range of relaxation parameters. these techniques generalize corresponding results obtained for matrix scaling by thibault et al. ( algorithms, 14 ( 5 ) : 143, 2021 ) and lehmann et al. ( optim. lett., 16 ( 8 ) : 2209 - - 2220, 2022 ). numerical experiments demonstrate that the proposed methods outperform the original operator sinkhorn iteration in certain applications.
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arxiv:2410.14104
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let $ \ mathbf { f } _ { 4 } $ be the unique ( up to isomorphism ) connected semisimple algebraic group over $ \ mathbb { q } $ of type $ \ mathrm { f } _ { 4 } $, with compact real points and split over $ \ mathbb { q } _ { p } $ for all primes $ p $. a conjectural computation by the author in arxiv : 2407. 05859 predicts the existence of a family of level one automorphic representations of $ \ mathbf { f } _ { 4 } $, which are expected to be functorial lifts of cuspidal representations of $ \ mathbf { pgl } _ { 2 } $ associated with hecke eigenforms. in this paper, we study the exceptional theta correspondence for $ \ mathbf { f } _ { 4 } \ times \ mathbf { pgl } _ { 2 } $, and establish the existence of such a family of automorphic representations for $ \ mathbf { f } _ { 4 } $. motivated by the work of pollack, our main tool is a notion of " exceptional theta series " on $ \ mathbf { pgl } _ { 2 } $, arising from certain automorphic representations of $ \ mathbf { f } _ { 4 } $. these theta series are holomorphic modular forms on $ \ mathbf { sl } _ { 2 } ( \ mathbb { z } ) $, with explicit fourier expansions, and span the entire space of level one cusp forms.
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arxiv:2501.19101
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spatial - temporal data contains rich information and has been widely studied in recent years due to the rapid development of relevant applications in many fields. for instance, medical institutions often use electrodes attached to different parts of a patient to analyse the electorencephal data rich with spatial and temporal features for health assessment and disease diagnosis. existing research has mainly used deep learning techniques such as convolutional neural network ( cnn ) or recurrent neural network ( rnn ) to extract hidden spatial - temporal features. yet, it is challenging to incorporate both inter - dependencies spatial information and dynamic temporal changes simultaneously. in reality, for a model that leverages these spatial - temporal features to fulfil complex prediction tasks, it often requires a colossal amount of training data in order to obtain satisfactory model performance. considering the above - mentioned challenges, we propose an adaptive federated relevance framework, namely fedrel, for spatial - temporal graph learning in this paper. after transforming the raw spatial - temporal data into high quality features, the core dynamic inter - intra graph ( diig ) module in the framework is able to use these features to generate the spatial - temporal graphs capable of capturing the hidden topological and long - term temporal correlation information in these graphs. to improve the model generalization ability and performance while preserving the local data privacy, we also design a relevance - driven federated learning module in our framework to leverage diverse data distributions from different participants with attentive aggregations of their models.
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arxiv:2206.03420
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we prove the convergence of the adams spectral sequence based on morava k - theory and relate it to the filtration by powers of the maximal ideal in the lubin - tate ring through a miller square. we use the filtration by powers to construct a spectral sequence relating the homology of the k - local sphere to derived functors of completion and express the latter as cohomology of the morava stabilizer group. as an application, we compute the zeroth limit at all primes and heights.
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arxiv:2111.06379
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structured pruning, especially channel pruning is widely used for the reduced computational cost and the compatibility with off - the - shelf hardware devices. among existing works, weights are typically removed using a predefined global threshold, or a threshold computed from a predefined metric. the predefined global threshold based designs ignore the variation among different layers and weights distribution, therefore, they may often result in sub - optimal performance caused by over - pruning or under - pruning. in this paper, we present a simple yet effective method, termed optimal thresholding ( ot ), to prune channels with layer dependent thresholds that optimally separate important from negligible channels. by using ot, most negligible or unimportant channels are pruned to achieve high sparsity while minimizing performance degradation. since most important weights are preserved, the pruned model can be further fine - tuned and quickly converge with very few iterations. our method demonstrates superior performance, especially when compared to the state - of - the - art designs at high levels of sparsity. on cifar - 100, a pruned and fine - tuned densenet - 121 by using ot achieves 75. 99 % accuracy with only 1. 46e8 flops and 0. 71m parameters.
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arxiv:2003.04566
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we first review the current knowledge of hipparcos systematic and random errors, in particular small - scale correlations. then, assuming gaussian parallax errors and using examples from the recent hipparcos literature, we show how random errors may be misinterpreted as systematic errors, or transformed into systematic errors. finally we summarise how to get unbiased estimates of absolute magnitudes and distances, using either bayesian or non - parametrical methods. these methods may be applied to get either mean quantities or individual estimates. in particular, we underline the notion of astrometry - based luminosity, which avoids the truncation biases and allows a full use of hipparcos samples.
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arxiv:astro-ph/9812094
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multiple - degrees - of - freedom free - space communication combining polarization and high - order spatial modes promises high - capacity communication channel. while high - order spatial modes have been widely exploited for dense coding and high - dimensional quantum information processing, the properties of polarization preservation of high - order spatial beams propagating in turbulent atmosphere have not been comprehensively investigated yet. here we focus on the properties of polarization preservation of partially coherent hermite - gaussian beams propagating along different atmospheric turbulence paths. the analytical expressions for the polarization of partially coherent hermite - gaussian beams propagating through atmospheric turbulence along different paths have been derived. it is shown that the larger the coherence length is, and the larger the beam order m, n are, the less the polarization is changed. we find that the evolution properties of the polarization in slant - down paths through turbulent atmosphere are similar to the case in free space if the condition zenith angle { \ xi } < { \ pi } / 4 is satisfied. while at a long propagation distance, evolution properties of polarization in horizontal paths of turbulent atmosphere differs much from that in free space and in slant paths. the results may allow one to choose the optimal propagation path in terms of specific applications, which is helpful for future experimental implementation of multiple - degrees - of - freedom free - space communication.
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arxiv:1603.05159
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how similar are two images? in computational pathology, where whole slide images ( wsis ) of digitally scanned tissue samples from patients can be multi - gigapixels in size, determination of degree of similarity between two wsis is a challenging task with a number of practical applications. in this work, we explore a novel strategy based on kernelized maximum mean discrepancy ( mmd ) analysis for determination of pairwise similarity between wsis. the proposed approach works by calculating mmd between two wsis using kernels over deep features of image patches. this allows representation of an entire dataset of wsis as a kernel matrix for wsi level clustering, weakly - supervised prediction of tp - 53 mutation status in breast cancer patients from their routine wsis as well as survival analysis with state of the art prediction performance. we believe that this work will open up further avenues for application of wsi - level kernels for predictive and prognostic tasks in computational pathology.
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arxiv:2301.09624
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we have used high - resolution spectra obtained with the multifiber facility flames at the very large telescope of the european southern observatory to derive kinematic properties and chemical abundances of fe, o, mg and si for 89 stars in the disk of the large magellanic cloud ( lmc ). the derived metallicity and [ alpha / fe ], obtained as the average of o, mg and si abundances, allow us to draw a preliminary scheme of the star formation history occurred in this region of the lmc. the derived metallicity distribution shows two main components : one component ( comprising ~ 84 % of the sample ) is peaked at [ fe / h ] = - 0. 48 dex and it shows an [ alpha / fe ] ratio slightly under solar ( [ alpha / fe ] ~ - 0. 1 dex ). this population was probably originated by the main star formation event occurred 3 - 4 gyr ago ( possibly triggered by tidal capture of the small magellanic cloud ). the other component ( comprising ~ 16 % of the sample ) is peaked at [ fe / h ] ~ - 1 dex and it shows an [ alpha / fe ] ~ 0. 2 dex. this population was probably generated during the long quiescent epoch of star formation in between the first episode and the most recent bursts. indeed, in our sample we do not find stars with chemical properties similar to the old lmc globular clusters nor to the iron - rich and alpha - poor stars recently found in the lmc globular cluster ngc 1718 and predicted to be also in the lmc field, thus suggesting that both these components are small ( < 1 % ) in the lmc disk population.
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arxiv:1210.0560
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the evolution of the magnetic moment and various features of the electronic structure of fcc gd are followed to reduced volume v / vo = 0. 125 using the lda + u correlated band method. the stability of the moment is substantial ; crude estimates of this signature of a possible ` ` mott transition ' ' in the 4f system suggest a critical pressure pc 500 gpa. the $ 4f $ occupation is found to increase under pressure due to broadening and lowering of the minority states. this trend is consistent with the interpretation of x - ray spectra of maddox et al. across the volume collapse transition at 59 gpa, and tends to support their suggestion that the delocalization of the 4f states in gd differs from the original abrupt picture, being instead a process that occurs over an extended range of pressure.
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arxiv:cond-mat/0606626
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thermodynamic properties of chiral spin liquids are investigated for a variant of the kitaev model defined on a decorated honeycomb lattice. using the quantum monte carlo simulation, we find that the model exhibits a finite - temperature phase transition associated with the time reversal symmetry breaking, in both topologically trivial and nontrivial regions. while changing the exchange constants, the phase transition changes from continuous to discontinuous one, apparently correlated with the change in the excitations from abelian to non - abelian anyons. we show this coincidence by computing the topological quantities : the chern number and the thermal hall conductivity. in addition, we find, as a diagnostic of the chiral spin liquids, successive crossovers with multi - stage entropy release above the critical temperature, which indicates that the hierarchical fractionalization of a quantum spin occurs differently between the two regions.
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arxiv:1506.01514
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we introduce and study co - dimension one area - minimizing locally rectifiable currents $ t $ with $ c ^ { 1, \ alpha } $ tangentially immersed boundary : $ \ partial t $ is locally a finite sum of orientable co - dimension two submanifolds which only intersect tangentially with equal orientation. we show that any such $ t $ is supported in a smooth hypersurface near any point on the support of $ \ partial t $ where $ t $ has tangent cone which is a hyperplane with constant orientation but non - constant multiplicity. we also introduce and study co - dimensional one area - minimizing locally rectifiable currents $ t $ with boundary having co - oriented mean curvature : $ \ partial t $ has generalized mean curvature $ h _ { \ partial t } = h \ nu _ { t } $ with $ h $ a real - valued function and $ \ nu _ { t } $ the generalized outward pointing unit normal of $ \ partial t $ with respect to $ t. $
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arxiv:1603.08568
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the paper is devoted to recent advances in stochastic modeling of anomalous kinetic processes observed in dielectric materials which are prominent examples of disordered ( complex ) systems. theoretical studies of dynamical properties of those " structures with variations " [ goldenfield and kadanoff 1999 science 284 87 - - 9 ] require application of such mathematical tools by means of which their random nature can be analyzed and, independently of the details differing various systems ( dipolar materials, glasses, semiconductors, liquid crystals, polymers, etc. ), the empirical universal kinetic patterns can be derived. we begin with a brief survey of the historical background of the dielectric relaxation study. after a short outline of the theoretical ideas providing the random tools applicable to modeling of relaxation phenomena, we present probabilistic implications for the study of the relaxation - rate distribution models. in the framework of the probability distribution of relaxation rates we consider description of complex systems, in which relaxing entities form random clusters interacting with each other and single entities. then we focus on stochastic mechanisms of the relaxation phenomenon. we discuss the diffusion approach and its usefulness for understanding of anomalous dynamics of the relaxing systems. we also discuss extensions of the diffusive approach to the systems under tempered random processes. useful relationships among different stochastic approaches to the anomalous dynamics of complex systems allow us to get a fresh look on this subject. the paper closes with a final discussion on achievements of stochastic tools describing the anomalous time evolution of the complex systems.
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arxiv:1703.06138
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in their article, entitled " towards a new crown indicator : some theoretical considerations, " waltman et al. ( 2010 ; at arxiv : 1003. 2167 ) show that the " old crown indicator " of cwts in leiden was mathematically inconsistent and that one should move to the normalization as applied in the " new crown indicator. " although we now agree about the statistical normalization, the " new crown indicator " inherits the scientometric problems of the " old " one in treating subject categories of journals as a standard for normalizing differences in citation behavior among fields of science. we further note that the " mean " is not a proper statistics for measuring differences among skewed distributions. without changing the acronym of " mncs, " one could define the " median normalized citation score. " this would relate the new crown indicator directly to the percentile approach that is, for example, used in the science and engineering indicators of us national science board ( 2010 ). the median is by definition equal to the 50th percentile. the indicator can thus easily be extended with the 1 % ( = 99th percentile ) most highly - cited papers ( bornmann et al., in press ). the seeming disadvantage of having to use non - parametric statistics is more than compensated by possible gains in the precision.
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arxiv:1010.2379
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in this paper, which is a sequel of [ bklv ], we study the convex - geometric properties of the cone of pseudoeffective $ n $ - cycles in the symmetric product $ c _ d $ of a smooth curve $ c $. we introduce and study the abel - jacobi faces, related to the contractibility properties of the abel - jacobi morphism and to classical brill - noether varieties. we investigate when abel - jacobi faces are non - trivial, and we prove that for $ d $ sufficiently large ( with respect to the genus of $ c $ ) they form a maximal chain of perfect faces of the tautological pseudoeffective cone ( which coincides with the pseudoeffective cone if $ c $ is a very general curve ).
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arxiv:1711.07725
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we examine the evaluation of the minimum information loss due to an unread local measurement in mixed states of bipartite systems, for a general entropic form. such quantity provides a measure of quantum correlations, reducing for pure states to the generalized entanglement entropy, while in the case of mixed states it vanishes just for classically correlated states with respect to the measured system, as the quantum discord. general stationary conditions are provided, together with their explicit form for general two - qubit states. closed expressions for the minimum information loss as measured by quadratic and cubic entropies are also derived for general states of two - qubit systems. as application, we analyze the case of states with maximally mixed marginals, where a general evaluation is provided, as well as x states and the mixture of two aligned states.
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arxiv:1112.1587
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the purpose of this paper is twofold. first, we introduce the notions of left - symmetric and left alternative structures on superspaces in characteristic 2. we describe their main properties and classify them in dimension 2. we show that left - symmetric structures can be queerified if and only if they are left - alternative. secondly, we present a method of lagrangian extension of lie superalgebras in characteristic 2 with a flat torsion - free connection. we show that any strongly polarized quasi - frobenius lie superalgebra can be obtained as a lagrangian extension. further, we demonstrate that lagrangian extensions are classified by a certain cohomology space that we introduce. to illustrate our constructions, all lagrangian extensions in dimension 4 have been described.
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arxiv:2501.15432
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assistive mobile robots are a transformative technology that helps persons with disabilities regain the ability to move freely. although autonomous wheelchairs significantly reduce user effort, they still require human input to allow users to maintain control and adapt to changing environments. brain computer interface ( bci ) stands out as a highly user - friendly option that does not require physical movement. current bci systems can understand whether users want to accelerate or decelerate, but they implement these changes in discrete speed steps rather than allowing for smooth, continuous velocity adjustments. this limitation prevents the systems from mimicking the natural, fluid speed changes seen in human self - paced motion. the authors aim to address this limitation by redesigning the perception - action cycle in a bci controlled robotic system : improving how the robotic agent interprets the user ' s motion intentions ( world state ) and implementing these actions in a way that better reflects natural physical properties of motion, such as inertia and damping. the scope of this paper focuses on the perception aspect. we asked and answered a normative question " what computation should the robotic agent carry out to optimally perceive incomplete or noisy sensory observations? " empirical eeg data were collected, and probabilistic representation that served as world state distributions were learned and evaluated in a generative adversarial network framework. the ros framework was established that connected with a gazebo environment containing a digital twin of an indoor space and a virtual model of a robotic wheelchair. signal processing and statistical analyses were implemented to identity the most discriminative features in the spatial - spectral - temporal dimensions, which are then used to construct the world model for the robotic agent to interpret user motion intentions as a bayesian observer.
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arxiv:2501.05610
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static solutions of large - $ n $ quantum dilaton gravity in $ 1 + 1 $ dimensions are analyzed and found to exhibit some unusual behavior. as expected from previous work, infinite - mass solutions are found describing a black hole in equilibrium with a bath of hawking radiation. surprisingly, the finite mass solutions are found to approach zero coupling both at the horizon and spatial infinity, with a ` ` bounce ' ' off of strong coupling in between. several new zero mass solutions - - candidate quantum vacua - - are also described.
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arxiv:hep-th/9203042
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we study the solvability of a general class of cross diffusion systems and establish the local and global existence of their strong solutions under the weakest assumption that they are vmo. this work simplifies the setting in our previous work [ 16 ] and provides new extensions which are more verifiable in applications.
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arxiv:1608.06151
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this work deals with the computation of the power spectrum of large - scale structure using the dynamical system approach for a multi - fluid universe in scalar - tensor theory of gravity. we use the $ 1 + 3 $ covariant approach to obtain evolution equations and study the behavior of the matter power spectrum of perturbation equations. the study is based on the equivalence between $ f ( r ) $ theory of gravity and scalar - tensor theory of gravity. we find that, for power - law $ ( r ^ { n } ) $ models, with $ 1 < n < 1. 3 $, we have the power spectrum evolving above general relativistic scale - invariant line. for $ n \ geq 1. 3 $, the power spectrum starts with constant amplitude then it experiences oscillations and eventually saturates at finite amplitude. such behavior is consistent with other observations in the literature. the result supports the ongoing investigations of the equivalence between $ f ( r ) $ and scalar - tensor theory at linear order.
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arxiv:2205.12036
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in this brief note we calculate the entanglement entropy in $ m ^ { \ otimes n } / s _ n $ symmetric orbifold cfts in the presence of topological defects, which were recently constructed in \ cite { gutperle : 2024vyp, knighton : 2024noc }. we consider both universal defects which realize $ rep ( s _ n ) $ non - invertible symmetry and non - universal defects. we calculate the sub - leading defect entropy / g - factor for defects at the boundary entangling surface as well as inside it.
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arxiv:2406.10967
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we measure the longitudinal conductivity $ \ sigma _ { xx } $ at frequencies $ 1. 246 { \ rm ghz } \ le f \ le 10. 05 $ ghz over a range of temperatures $ 235 { \ rm mk } \ le t \ le 4. 2 $ k with particular emphasis on the quantum hall plateaus. we find that $ re ( \ sigma _ { xx } ) $ scales linearly with frequency for a range of magnetic field around the center of the plateaus, i. e. where $ \ sigma _ { xx } ( \ omega ) \ gg \ sigma _ { xx } ^ { dc } $. the width of this scaling region decreases with higher temperature and vanishes by 1. 2 k altogether. comparison between localization length determined from $ \ sigma _ { xx } ( \ omega ) $ and dc measurements on the same wafer show good agreement.
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arxiv:cond-mat/0012387
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we discuss the hypothesis that the constituents of dark matter in the galactic halo are primordial intermediate - mass black holes ( pimbhs ). the status of axions and wimps is discussed, as are the methods for detecting pimbhs with emphasis on microlensing. the role of the angular momentum j of the pimbhs in their escaping previous detection is considered.
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arxiv:1705.04373
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we consider the interference pattern for the medium - induced gluon radiation produced by a color singlet quark - antiquark antenna embedded in a qcd medium with size $ l $ and ` jet quenching ' parameter $ \ hat q $. within the bdmps - z regime, we demonstrate that, for a dipole opening angle $ \ theta _ { q \ bar q } \ gg \ theta _ c \ equiv { 2 } / { \ sqrt { \ hat q l ^ 3 } } $, the interference between the medium - - induced gluon emissions by the quark and the antiquark is suppressed with respect to the direct emissions. this is so since direct emissions are delocalized throughout the medium and thus yield contributions proportional to $ l $ while interference occurs only between emissions at early times, when both sources remain coherent. thus, for $ \ tqq \ gg \ theta _ c $, the medium - induced radiation is the sum of the two spectra individually produced by the quark and the antiquark, without coherence effects like angular ordering. for $ \ tqq \ ll \ theta _ c $, the medium - - induced radiation vanishes.
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arxiv:1106.3864
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multivariate elliptically - contoured distributions are widely used for modeling economic and financial data. we study the problem of estimating moment parameters of a semi - parametric elliptical model in a high - dimensional setting. such estimators are useful for financial data analysis and quadratic discriminant analysis. for low - dimensional elliptical models, efficient moment estimators can be obtained by plugging in an estimate of the precision matrix. natural generalizations of the plug - in estimator to high - dimensional settings perform unsatisfactorily, due to estimating a large precision matrix. do we really need a sledgehammer to crack an egg? fortunately, we discover that moment parameters can be efficiently estimated without estimating the precision matrix in high - dimension. we propose a marginal aggregation estimator ( mae ) for moment parameters. the mae only requires estimating the diagonal of covariance matrix and is convenient to implement. with mild sparsity on the covariance structure, we prove that the asymptotic variance of mae is the same as the ideal plug - in estimator which knows the true precision matrix, so mae is asymptotically efficient. we also extend mae to a block - wise aggregation estimator ( bae ) when estimates of diagonal blocks of covariance matrix are available. the performance of our methods is validated by extensive simulations and an application to financial returns.
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arxiv:1812.05697
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there is substantial evidence that the initial mass function ( imf ) may be a function of the local star formation conditions. in particular, the imf is predicted to flatten with increasing local luminosity density, with the formation of massive stars being preferentially enhanced in brighter regions. if imf gradients are general features of galaxies, several previous astrophysical measurements, such as the surface mass densities of spirals ( obtained assuming constant mass to light ratios ), were plagued by substantial systematic errors. in this letter, calculations which account for possible imf gradients are presented of surface densities of spiral galaxies. compared to previous estimates, the mass densities corrected for imf gradients are higher in the outer regions of the disks. for a model based on the milky way but with an imf scaled according to r136, the rotation curve without the traditional dark halo component falls with galactocentric radius, though slower than it would without imf gradients. for a second model of the milky way in which the imf gradient is increased by 50 %, the rotation curve is approximately flat in the outer disk, with a rotational velocity below ~ 220 km / s only before the traditional dark halo component is added. these results, if generalizable to other galaxies, not only call into question the assertion that dark matter halos are compatible with the flat rotation curves of spiral galaxies, but also may clarify our understanding of a wide variety of other astrophysical phenomena such as the g - dwarf problem, metallicity gradients, and the tully - fisher relation.
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arxiv:astro-ph/9802215
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we present a type inference algorithm for lambda - terms in elementary affine logic using linear constraints. we prove that the algorithm is correct and complete.
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arxiv:cs/0305011
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federated learning ( fl ) has attracted widespread attention because it supports the joint training of models by multiple participants without moving private dataset. however, there are still many security issues in fl that deserve discussion. in this paper, we consider three major issues : 1 ) how to ensure that the training process can be publicly audited by any third party ; 2 ) how to avoid the influence of malicious participants on training ; 3 ) how to ensure that private gradients and models are not leaked to third parties. many solutions have been proposed to address these issues, while solving the above three problems simultaneously is seldom considered. in this paper, we propose a publicly auditable and privacy - preserving federated learning scheme that is resistant to malicious participants uploading gradients with wrong directions and enables anyone to audit and verify the correctness of the training process. in particular, we design a robust aggregation algorithm capable of detecting gradients with wrong directions from malicious participants. then, we design a random vector generation algorithm and combine it with zero sharing and blockchain technologies to make the joint training process publicly auditable, meaning anyone can verify the correctness of the training. finally, we conduct a series of experiments, and the experimental results show that the model generated by the protocol is comparable in accuracy to the original fl approach while keeping security advantages.
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arxiv:2405.04029
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in this paper, we study the problem of stochastic linear bandits with finite action sets. most of existing work assume the payoffs are bounded or sub - gaussian, which may be violated in some scenarios such as financial markets. to settle this issue, we analyze the linear bandits with heavy - tailed payoffs, where the payoffs admit finite $ 1 + \ epsilon $ moments for some $ \ epsilon \ in ( 0, 1 ] $. through median of means and dynamic truncation, we propose two novel algorithms which enjoy a sublinear regret bound of $ \ widetilde { o } ( d ^ { \ frac { 1 } { 2 } } t ^ { \ frac { 1 } { 1 + \ epsilon } } ) $, where $ d $ is the dimension of contextual information and $ t $ is the time horizon. meanwhile, we provide an $ \ omega ( d ^ { \ frac { \ epsilon } { 1 + \ epsilon } } t ^ { \ frac { 1 } { 1 + \ epsilon } } ) $ lower bound, which implies our upper bound matches the lower bound up to polylogarithmic factors in the order of $ d $ and $ t $ when $ \ epsilon = 1 $. finally, we conduct numerical experiments to demonstrate the effectiveness of our algorithms and the empirical results strongly support our theoretical guarantees.
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arxiv:2004.13465
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we have recently derived a manifestly covariant evolution law, under the geometrical optics approximation of the vacuum maxwell ' s equations, for the electric field along null geodesics in a general spacetime, relative to an arbitrary set of instantaneous observers [ arxiv : 2004. 03496 ]. as one of its applications, we derive here the final detected intensity signal arising from a prototypical laser interferometric gravitational wave ( gw ) michelson - morley detector, comoving with transverse traceless ( tt ) observers, valid for both long and short gw wavelengths. one of our main results is the presentation of the integrated null geodesic parametric equations exchanged between two tt observers in terms of explicitly observable quantities and the profile of the plane gw packet. this allows us to revisit the derivation of the consequential radar distance and doppler shift, taking the opportunity to discuss some related subtle conceptual issues and how they might affect the interferometric process. another achievement is the calculation of the electric field in each arm up to the detection event, for any relative orientations of the arms and the gw direction. the main quantitative result is the new expression for the final interference pattern, for normal gw incidence, which turns out to have three contributions : ( i ) the well - known traditional one due to the difference in optical paths, and two new ones due to ( ii ) the doppler effect, and ( iii ) the divergence of the laser beams. the quantitative relevance of the last two contributions is compared to the traditional one and shown to be negligible within the geometrical optics regime of light. although in general further contributions from the non - parallel transport of the polarization vector are expected, again in the case of gw normal incidence, such a vector is indeed parallel transported, and those contributions are absent.
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arxiv:2108.11795
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we report on the detection of hco + and 12co emission in the rotational transition j = 1 - 0 in the vicinity of the shock front at the southern border of the supernova remnant rcw 103, where previous infrared observations suggest an interaction with a molecular cloud. the observations were carried out with the australian millimeter radiotelescope at mopra. we observed a depletion of hco + behind the supernova shock front. in addition, we studied the interstellar medium over an extended region towards rcw 103 based on archival 21 cm hi line observations from the australia telescope compact array ( atca ) and the parkes telescope. no atomic gas is observed in emission in coincidence with the molecular feature. this absence is interpreted in terms of self absorption processes.
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arxiv:astro-ph/0603611
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we discuss the existence of stationary solutions for logistic diffusion equations of fisher - kolmogoroff - petrovski - piskunov type driven by the superposition of fractional operators in a bounded region with " hostile " environmental conditions, modeled by homogeneous external dirichlet data. we provide a range of results on the existence and nonexistence of solutions tied to the spectral properties of the ambient space, corresponding to either survival or extinction of the population. we also discuss how the possible presence of nonlocal phenomena of concentration and diffusion affect the endurance or disappearance of the population. in particular, we give examples in which both classical and anomalous diffusion leads to the extinction of the species, while the presence of an arbitrarily small concentration pattern enables survival.
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arxiv:2501.12967
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we establish the integrability of the last open case in the kozlov - treshchev classification of birkhoff integrable hamiltonian systems. the technique used is a modification of the so called quadratic lax pair for $ d _ n $ toda lattice combined with a method used by m. ranada in proving the integrability of the sklyanin case.
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arxiv:math-ph/0701027
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we introduce dissipative effects in the effective field theory of hydrodynamics. we do this in a model - independent fashion by coupling the long - distance degrees of freedom explicitly kept in the effective field theory to a generic sector that " lives in the fluid ", which corresponds physically to the microscopic constituents of the fluid. at linear order in perturbations, the symmetries, the derivative expansion, and the assumption that this microscopic sector is thermalized, allow us to characterize the leading dissipative effects at low frequencies via three parameters only, which correspond to bulk viscosity, shear viscosity, and - - in the presence of a conserved charge - - heat conduction. using our methods we re - derive the kubo relations for these transport coefficients.
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arxiv:1211.6461
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the economic feasibility of nuclear microreactors will depend on minimizing operating costs through advancements in autonomous control, especially when these microreactors are operating alongside other types of energy systems ( e. g., renewable energy ). this study explores the application of deep reinforcement learning ( rl ) for real - time drum control in microreactors, exploring performance in regard to load - following scenarios. by leveraging a point kinetics model with thermal and xenon feedback, we first establish a baseline using a single - output rl agent, then compare it against a traditional proportional - integral - derivative ( pid ) controller. this study demonstrates that rl controllers, including both single - and multi - agent rl ( marl ) frameworks, can achieve similar or even superior load - following performance as traditional pid control across a range of load - following scenarios. in short transients, the rl agent was able to reduce the tracking error rate in comparison to pid. over extended 300 - minute load - following scenarios in which xenon feedback becomes a dominant factor, pid maintained better accuracy, but rl still remained within a 1 % error margin despite being trained only on short - duration scenarios. this highlights rl ' s strong ability to generalize and extrapolate to longer, more complex transients, affording substantial reductions in training costs and reduced overfitting. furthermore, when control was extended to multiple drums, marl enabled independent drum control as well as maintained reactor symmetry constraints without sacrificing performance - - an objective that standard single - agent rl could not learn. we also found that, as increasing levels of gaussian noise were added to the power measurements, the rl controllers were able to maintain lower error rates than pid, and to do so with less control effort.
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arxiv:2504.00156
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black hole spacetimes asymptotic to five - dimensional anti - de sitter spacetime are of great interest in connection with the string - gauge duality. in the rotating case, such black holes tend to become unstable, in several different ways, if their specific angular momenta fall in certain ranges. here we consider the well - known emparan - myers fragmentation instability for singly rotating ads $ _ 5 $ - kerr black holes, paying particular attention to the case where the specific angular momentum exceeds the asymptotic ads $ _ 5 $ curvature length scale.
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arxiv:2005.03869
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we present an approach to turbulence closure based on mixing length theory with three - dimensional fluctuations against a two - dimensional background. this model is intended to be rapidly computable for implementation in stellar evolution software and to capture a wide range of relevant phenomena with just a single free parameter, namely the mixing length. we incorporate magnetic, rotational, baroclinic and buoyancy effects exactly within the formalism of linear growth theories with nonlinear decay. we treat differential rotation effects perturbatively in the corotating frame using a novel controlled approximation which matches the time evolution of the reference frame to arbitrary order. we then implement this model in an efficient open source code and discuss the resulting turbulent stresses and transport coefficients. we demonstrate that this model exhibits convective, baroclinic and shear instabilities as well as the magnetorotational instability ( mri ). it also exhibits non - linear saturation behaviour, and we use this to extract the asymptotic scaling of various transport coefficients in physically interesting limits.
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arxiv:1803.00579
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this paper introduces a novel compatibility attack to detect a steganographic message embedded in the dct domain of a jpeg image at high - quality factors ( close to 100 ). because the jpeg compression is not a surjective function, i. e. not every dct blocks can be mapped from a pixel block, embedding a message in the dct domain can create incompatible blocks. we propose a method to find such a block, which directly proves that a block has been modified during the embedding. this theoretical method provides many advantages such as being completely independent to cover source mismatch, having good detection power, and perfect reliability since false alarms are impossible as soon as incompatible blocks are found. we show that finding an incompatible block is equivalent to proving the infeasibility of an integer linear programming problem. however, solving such a problem requires considerable computational power and has not been reached for 8x8 blocks. instead, a timing attack approach is presented to perform steganalysis without potentially any false alarms for large computing power.
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arxiv:2306.01317
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recent text and image foundation models are incredibly impressive, and these models are attracting an ever - increasing portion of research resources. in this position piece we aim to shift the ml research community ' s priorities ever so slightly to a different modality : tabular data. tabular data is the dominant modality in many fields, yet it is given hardly any research attention and significantly lags behind in terms of scale and power. we believe the time is now to start developing tabular foundation models, or what we coin a large tabular model ( ltm ). ltms could revolutionise the way science and ml use tabular data : not as single datasets that are analyzed in a vacuum, but contextualized with respect to related datasets. the potential impact is far - reaching : from few - shot tabular models to automating data science ; from out - of - distribution synthetic data to empowering multidisciplinary scientific discovery. we intend to excite reflections on the modalities we study, and convince some researchers to study large tabular models.
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arxiv:2405.01147
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multiobjective evolutionary algorithms ( moeas ) have been successfully applied to a number of constrained optimization problems. many of them adopt mutation and crossover operators from differential evolution. however, these operators do not explicitly utilise features of fitness landscapes. to improve the performance of algorithms, this paper aims at designing a search operator adapting to fitness landscapes. through an observation, we find that principle component analysis ( pca ) can be used to characterise fitness landscapes. based on this finding, a new search operator, called pca - projection, is proposed. in order to verify the effectiveness of pca - projection, we design two algorithms enhanced with pca - projection for solving constrained optimization problems, called pmode and heco - pde, respectively. experiments have been conducted on the ieee cec 2017 competition benchmark suite in constrained optimisation. pmode and heco - pde are compared with the algorithms from the ieee cec 2018 competition and another recent moea for constrained optimisation. experimental results show that an algorithm enhanced with pca - projection performs better than its corresponding opponent without this operator. furthermore, heco - pde is ranked first on all dimensions according to the competition rules. this study reveals that decomposition - based moeas, such as heco - pde, are competitive with best single - objective and multiobjective evolutionary algorithms for constrained optimisation, but moeas based on non - dominance, such as pmode, may not.
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arxiv:1805.00272
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we show that the relativistic dynamics in a gaussian random electromagnetic field can be approximated by the relativistic diffusion of schay and dudley. lorentz invariant dynamics in the proper time leads to the diffusion in the proper time. the dynamics in the laboratory time gives the diffusive transport equation corresponding to the juettner equilibrium at the inverse temperature \ beta ^ { - 1 } = mc ^ { 2 }. the diffusion constant is expressed by the field strength correlation function ( kubo ' s formula ).
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arxiv:1104.1790
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we demonstrate an on - chip lithium niobate micro - disk laser based on hydrogen cyanide ( h13c14n ) gas saturation absorption method for frequency stabilization. the laser chip consists of two main components : a micro - disk laser and a combined racetrack ring cavity. by operating on the h13c14n p12 absorption line at 1551. 3 nm, the laser frequency can be precisely stabilized. the laser demonstrates remarkable stability, achieving a best stability value of 9 * 10 ^ - 9. furthermore, the short - term stability, evaluated over continuous time intervals of 35 seconds, showcases exceptional performance. additionally, the residual drift remains well below 30 mhz.
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arxiv:2407.16140
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a central feature of complex systems is the relevance and entanglement of different levels of description. for instance, the dynamics of ecosystems can be alternatively described in terms of large ecological processes and classes of organisms, or of individual species and their relations. low - dimensional heuristic ' macroscopic ' models that are widely used to capture ecological relationships - - and commonly evidence out - of equilibrium regimes - - implicitly assume that species - level ' microscopic ' heterogeneity can be neglected. here, we address the stability of such macroscopic descriptions to the addition of disordered microscopic interactions. we find that increased heterogeneity can stabilize collective as well as species fluctuations - - contrary to the well - known destabilizing effect of disorder on fixed points. we analytically find the conditions for the existence of heterogeneity - driven equilibria, and relate their stability to a mismatch in microscopic time scales. this may shed light onto the empirical observation that many - species ecosystems often appear stable at aggregated levels despite highly diverse interactions and large fluctuations at the species level.
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arxiv:2411.14969
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algorithmic decision systems are increasingly used in areas such as hiring, school admission, or loan approval. typically, these systems rely on labeled data for training a classification model. however, in many scenarios, ground - truth labels are unavailable, and instead we have only access to imperfect labels as the result of ( potentially biased ) human - made decisions. despite being imperfect, historical decisions often contain some useful information on the unobserved true labels. in this paper, we focus on scenarios where only imperfect labels are available and propose a new fair ranking - based decision system based on monotonic relationships between legitimate features and the outcome. our approach is both intuitive and easy to implement, and thus particularly suitable for adoption in real - world settings. more in detail, we introduce a distance - based decision criterion, which incorporates useful information from historical decisions and accounts for unwanted correlation between protected and legitimate features. through extensive experiments on synthetic and real - world data, we show that our method is fair in the sense that a ) it assigns the desirable outcome to the most qualified individuals, and b ) it removes the effect of stereotypes in decision - making, thereby outperforming traditional classification algorithms. additionally, we are able to show theoretically that our method is consistent with a prominent concept of individual fairness which states that " similar individuals should be treated similarly. "
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arxiv:2102.04565
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the prevailing belief propagated by nba league observers is that the workload of the nba season dramatically influences a player ' s performance $ ^ { 1, 2, 3, 4, 5 } $. we offer an analysis of cross game player fatigue that calls into question the empirical validity of these claims. the analysis is split into three observational studies on prior nba seasons. first, to offer an analysis generalized to the whole league, we conduct an examination of relative workloads with in - game player tracking data as a proxy for exertion. second, to introduce a more granular perspective, we conduct a case study of the effectiveness of load management for kawhi leonard. third, to extend the analysis to a broader set of fatigue sources, we examine the impact of schedule features structurally imposed on teams. all three analyses indicate the impact of cumulative player fatigue on game outcomes is minimal. as a result, we assert in the context of the measures already taken by teams to maintain the health of their players, $ ^ 6 $ the impact of fatigue in the nba is overstated.
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arxiv:2112.14649
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a variational approach is developed for bound state calculations in three - and four - electron atomic systems. this approach can be applied to determine, in principle, an arbitrary bound state in three - and four - electron ions and atoms. our variational wave functions are constructed from four - and five - body gaussoids which depend upon the six ( $ r _ { 12 }, r _ { 13 }, r _ { 14 }, r _ { 23 }, r _ { 24 }, r _ { 34 } $ ) and ten ( $ r _ { 12 }, r _ { 13 }, r _ { 14 }, r _ { 15 }, r _ { 23 }, r _ { 24 }, r _ { 25 }, r _ { 34 }, r _ { 35 } $ and $ r _ { 45 } $ ) relative coordinates, respectively. the approach allows one to operate with the different number of electron spin functions. in particular, the trial wave functions for the $ { } ^ 1s $ - states in four - electron atomic systems include the two independent spin functions $ \ chi _ 1 = \ alpha \ beta \ alpha \ beta + \ beta \ alpha \ beta \ alpha - \ beta \ alpha \ alpha \ beta - \ alpha \ beta \ beta \ alpha $ and $ \ chi _ 2 = 2 \ alpha \ alpha \ beta \ beta + 2 \ beta \ beta \ alpha \ alpha - \ beta \ alpha \ alpha \ beta - \ alpha \ beta \ beta \ alpha - \ beta \ alpha \ beta \ alpha - \ alpha \ beta \ alpha \ beta $. we also discuss the construction of variational wave functions for the excited $ 2 ^ 3s $ - states in four - electron atomic systems.
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arxiv:1008.2168
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effective control of magnetic phases in two - dimensional magnets would constitute crucial progress in spintronics, holding great potential for future computing technologies. here, we report a new approach of leveraging tunneling current as a tool for controlling spin states in cri3. we reveal that a tunneling current can deterministically switch between spin - parallel and spin - antiparallel states in few - layer cri3, depending on the polarity and amplitude of the current. we propose a mechanism involving nonequilibrium spin accumulation in the graphene electrodes in contact with the cri3 layers. we further demonstrate tunneling current - tunable stochastic switching between multiple spin states of the cri3 tunnel devices, which goes beyond conventional bi - stable stochastic magnetic tunnel junctions and has not been documented in two - dimensional magnets. our findings not only address the existing knowledge gap concerning the influence of tunneling currents in controlling the magnetism in two - dimensional magnets, but also unlock possibilities for energy - efficient probabilistic and neuromorphic computing.
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arxiv:2410.19255
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" the price of robustness " by bertsimas and sim represented a breakthrough in the development of a tractable robust counterpart of linear programming problems. however, the central modeling assumption that the deviation band of each uncertain parameter is single may be too limitative in practice : experience indeed suggests that the deviations distribute also internally to the single band, so that getting a higher resolution by partitioning the band into multiple sub - bands seems advisable. the critical aim of our work is to close the knowledge gap about the adoption of a multi - band uncertainty set in robust optimization : a general definition and intensive theoretical study of a multi - band model are actually still missing. our new developments have been also strongly inspired and encouraged by our industrial partners, which have been interested in getting a better modeling of arbitrary distributions, built on historical data of the uncertainty affecting the considered real - world problems. in this paper, we study the robust counterpart of a linear programming problem with uncertain coefficient matrix, when a multi - band uncertainty set is considered. we first show that the robust counterpart corresponds to a compact lp formulation. then we investigate the problem of separating cuts imposing robustness and we show that the separation can be efficiently operated by solving a min - cost flow problem. finally, we test the performance of our new approach to robust optimization on realistic instances of a wireless network design problem subject to uncertainty.
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arxiv:1208.6322
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rough set is one of the important methods for rule acquisition and attribute reduction. the current goal of rough set attribute reduction focuses more on minimizing the number of reduced attributes, but ignores the spatial similarity between reduced and decision attributes, which may lead to problems such as increased number of rules and limited generality. in this paper, a rough set attribute reduction algorithm based on spatial optimization is proposed. by introducing the concept of spatial similarity, to find the reduction with the highest spatial similarity, so that the spatial similarity between reduction and decision attributes is higher, and more concise and widespread rules are obtained. in addition, a comparative experiment with the traditional rough set attribute reduction algorithms is designed to prove the effectiveness of the rough set attribute reduction algorithm based on spatial optimization, which has made significant improvements on many datasets.
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arxiv:2405.09292
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laboratory experiments reveal that variations in bottom topography can qualitatively alter the distribution of randomized surface waves. a normally - distributed, unidirectional wave field becomes highly skewed and non - gaussian upon encountering an abrupt depth transition. a short distance downstream of the transition, wave statistics conform closely to a gamma distribution, affording simple estimates for skewness, kurtosis, and other statistical properties. importantly, the exponential decay of the gamma distribution is much slower than gaussian, signifying that extreme events occur more frequently. under the conditions considered here, the probability of a rogue wave can increase by a factor of 50 or more. we also report on the surface - slope statistics and the spectral content of the waves produced in the experiments.
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arxiv:1808.07958
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the matter - antimatter asymmetry problem, corresponding to the virtual nonexistence of antimatter in the universe, is one of the greatest mysteries of cosmology. within the framework of the generation model ( gm ) of particle physics, it is demonstrated that the matter - antimatter asymmetry problem may be understood in terms of the composite leptons and quarks of the gm. it is concluded that there is essentially no matter - antimatter asymmetry in the present universe and that the observed hydrogen - antihydrogen asymmetry may be understood in terms of statistical fluctuations associated with the complex many - body processes involved in the formation of either a hydrogen atom or an antihydrogen atom.
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arxiv:1609.04034
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we report a simple method for the creation of bose - einstein condensates of $ ^ { 85 } $ rb by direct evaporation in a crossed optical dipole trap. the independent control of the trap frequencies and magnetic bias field afforded by the trapping scheme permits full control of the trapped atomic sample, enabling the collision parameters to be easily manipulated to achieve efficient evaporation in the vicinity of the 155 g feshbach resonance. we produce nearly pure condensates of up to $ 4 \ times10 ^ 4 $ atoms and demonstrate the tunable nature of the atomic interactions.
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arxiv:1203.6598
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a new ultra low - level counting setup has been installed in the shallow - underground laboratory felsenkeller in dresden, germany. it includes a high - purity germanium detector ( hpge ) of 163 \ % relative efficiency within passive and active shields. the passive shield consists of 45m rock overburden ( 140 meters water equivalent ), 40 cm of low - activity concrete, and a lead and copper castle enclosed by an anti - radon box. the passive shielding alone is found to reduce the background rate to rates comparable to other shallow - underground laboratories. an additional active veto is given by five large plastic scintillation panels surrounding the setup. it further reduces the background rate by more than one order of magnitude down to 116 $ \ pm $ 1 kg $ ^ { - 1 } $ d $ ^ { - 1 } $ in an energy interval of 40 - 2700 kev. this low background rate is unprecedented for shallow - underground laboratories and close to deep underground laboratories.
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arxiv:2301.03905
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a \ emph { repdigit } is a natural number greater than 10 which has all of its base - 10 digits the same. in this paper we find all examples of two repdigits adding to a square. the proofs lead to interesting questions about consecutive quadratic residues and non - residues, and provide an elementary application of elliptic curves.
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arxiv:1607.06681
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a generic feature of weakly interacting massive particle ( wimp ) dark matter models is the emission of photons over a broad energy band resulting from the stable yields of dark matter pair annihilation. inverse compton scattering off cosmic microwave background photons of energetic electrons and positrons produced in dark matter annihilation is expected to produce significant diffuse x - ray emission. dwarf galaxies are ideal targets for this type of dark matter search technique, being nearby, dark matter dominated systems free of any astrophysical diffuse x - ray background. in this paper, we present the first systematic study of x - ray observations of local dwarf galaxies aimed at the search for wimp dark matter. we outline the optimal energy and angular ranges for current telescopes, and analyze the systematic uncertainties connected to electron / positron diffusion. we do not observe any significant x - ray excess, and translate this null result into limits on the mass and pair annihilation cross section for particle dark matter. our results indicate that x - ray observations of dwarf galaxies currently constrain dark matter models at the same level or even more strongly than gamma - ray observations of the same systems, although at the expenses of introducing additional assumptions and related uncertainties in the modeling of diffusion and energy loss processes. the limits we find constrain portions of the supersymmetric parameter space, particularly if the effect of dark matter substructures is included. finally, we comment on the role of future x - ray satellites ( e. g. constellation - x, xeus ) and on their complementarity with glast and other gamma - ray telescopes in the quest for particle dark matter.
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arxiv:0805.1054
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a theorem of blackwell about comparison between information structures in classical statistics is given an analogue in the quantum probabilistic setup. the theorem provides an operational interpretation for trace - preserving completely positive maps, which are the natural quantum analogue of classical stochastic maps. the proof of the theorem relies on the separation theorem for convex sets and on quantum teleportation.
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arxiv:quant-ph/0410233
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the development of advanced 3d sensors has enabled many objects to be captured in the wild at a large scale, and a 3d object recognition system may therefore encounter many objects for which the system has received no training. zero - shot learning ( zsl ) approaches can assist such systems in recognizing previously unseen objects. applying zsl to 3d point cloud objects is an emerging topic in the area of 3d vision, however, a significant problem that zsl often suffers from is the so - called hubness problem, which is when a model is biased to predict only a few particular labels for most of the test instances. we observe that this hubness problem is even more severe for 3d recognition than for 2d recognition. one reason for this is that in 2d one can use pre - trained networks trained on large datasets like imagenet, which produces high - quality features. however, in the 3d case there are no such large - scale, labelled datasets available for pre - training which means that the extracted 3d features are of poorer quality which, in turn, exacerbates the hubness problem. in this paper, we therefore propose a loss to specifically address the hubness problem. our proposed method is effective for both zero - shot and generalized zero - shot learning, and we perform extensive evaluations on the challenging datasets modelnet40, modelnet10, mcgill and shrec2015. a new state - of - the - art result for both zero - shot tasks in the 3d case is established.
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arxiv:1907.06371
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see also for a less ambiguous symbol. ≡ ( triple bar ) 1. denotes an identity ; that is, an equality that is true whichever values are given to the variables occurring in it. 2. in number theory, and more specifically in modular arithmetic, denotes the congruence modulo an integer. 3. may denote a logical equivalence. { \ displaystyle \ cong } 1. may denote an isomorphism between two mathematical structures, and is read as " is isomorphic to ". 2. in geometry, may denote the congruence of two geometric shapes ( that is the equality up to a displacement ), and is read " is congruent to ". = = comparison = = < ( less - than sign ) 1. strict inequality between two numbers ; means and is read as " less than ". 2. commonly used for denoting any strict order. 3. between two groups, may mean that the first one is a proper subgroup of the second one. > ( greater - than sign ) 1. strict inequality between two numbers ; means and is read as " greater than ". 2. commonly used for denoting any strict order. 3. between two groups, may mean that the second one is a proper subgroup of the first one. ≤ 1. means " less than or equal to ". that is, whatever a and b are, a ≤ b is equivalent to a < b or a = b. 2. between two groups, may mean that the first one is a subgroup of the second one. ≥ 1. means " greater than or equal to ". that is, whatever a and b are, a ≥ b is equivalent to a > b or a = b. 2. between two groups, may mean that the second one is a subgroup of the first one. and { \ displaystyle \ ll { \ text { and } } \ gg } 1. means " much less than " and " much greater than ". generally, much is not formally defined, but means that the lesser quantity can be neglected with respect to the other. this is generally the case when the lesser quantity is smaller than the other by one or several orders of magnitude. 2. in measure theory, μ ν { \ displaystyle \ mu \ ll \ nu } means that the measure μ { \ displaystyle \ mu } is absolutely continuous with respect to the measure ν { \ displaystyle \ nu }. { \ displaystyle \ leqq } a rarely used symbol, generally
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https://en.wikipedia.org/wiki/Glossary_of_mathematical_symbols
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decision trees ( dts ) embody interpretable classifiers. dts have been advocated for deployment in high - risk applications, but also for explaining other complex classifiers. nevertheless, recent work has demonstrated that predictions in dts ought to be explained with rigorous approaches. although rigorous explanations can be computed in polynomial time for dts, their size may be beyond the cognitive limits of human decision makers. this paper investigates the computation of { \ delta } - relevant sets for dts. { \ delta } - relevant sets denote explanations that are succinct and provably precise. these sets represent generalizations of rigorous explanations, which are precise with probability one, and so they enable trading off explanation size for precision. the paper proposes two logic encodings for computing smallest { \ delta } - relevant sets for dts. the paper further devises a polynomial - time algorithm for computing { \ delta } - relevant sets which are not guaranteed to be subset - minimal, but for which the experiments show to be most often subset - minimal in practice. the experimental results also demonstrate the practical efficiency of computing smallest { \ delta } - relevant sets.
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arxiv:2205.09569
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we present measurements of the afterglow signatures in nai ( tl ) and csi ( tl ) detector modules as part of the background and transient observer ( bto ) mission detector trade - study. bto is a nasa student collaboration project flying on the compton spectrometer and imager ( cosi ) small explorer mission in 2027. the detectors utilized in this study are cylindrical in shape with a height and diameter of 5. 1 cm and were read out by silicon photomultipliers ( sipms ). we conducted a radiation campaign at the himac accelerator in japan where the scintillators were irradiated with a 230 mev / u helium beam ( he beam ) and 350 mev / u carbon beam ( c beam ). we find that both the csi and nai scintillators exhibit afterglow signatures when irradiated with the c and he beams. the csi crystal exhibits a stronger afterglow intensity with afterglow pulses occurring for an average 2. 40 ms for c and 0. 9 ms for he after the initial particle pulse. the duration of afterglow pulses in csi is 8. 6x and 5. 6x the afterglow signal duration in nai for c and he ( 0. 28 ms and 0. 16 ms, respectively ). although csi has advantages such as a higher light yield and radiation hardness, the stronger afterglows in the csi detector increase the complexity of the electronics and lead to a ~ 7x larger dead time per afterglow event or a ~ 3x higher energy threshold value. we use the measured dead times to predict the amount of observing time lost to afterglow - inducing events for an instrument like bto in low earth orbit. we simulate the background rates in a bto - like orbit and find a total value of 114 counts / s for the full two - detector system. based on the particle energies in the himac experiment, we then determine that an event with sufficient energy to produce an afterglow signal occurs once every ~ 70 s and ~ 1. 4 s in nai and csi detectors, respectively. thus, we conclude that nai is the better choice for the bto mission.
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arxiv:2501.16434
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multi - layered network exploration ( mulane ) problem is an important problem abstracted from many applications. in mulane, there are multiple network layers where each node has an importance weight and each layer is explored by a random walk. the mulane task is to allocate total random walk budget $ b $ into each network layer so that the total weights of the unique nodes visited by random walks are maximized. we systematically study this problem from offline optimization to online learning. for the offline optimization setting where the network structure and node weights are known, we provide greedy based constant - ratio approximation algorithms for overlapping networks, and greedy or dynamic - programming based optimal solutions for non - overlapping networks. for the online learning setting, neither the network structure nor the node weights are known initially. we adapt the combinatorial multi - armed bandit framework and design algorithms to learn random walk related parameters and node weights while optimizing the budget allocation in multiple rounds, and prove that they achieve logarithmic regret bounds. finally, we conduct experiments on a real - world social network dataset to validate our theoretical results.
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arxiv:2106.05065
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galactic disk. the third component of the system was found to be a member of the halo population in terms of age, $ \ alpha $ elements and metal abundance. given the different chemical abundances and age of b compared to a, this suggests that the third component was captured by the central system in a region with weak gravitational interactions far beyond the galactic disc.
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arxiv:2412.04540
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