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we curry the elementary arithmetic operations of addition and multiplication to give monotone injections on n, and describe & study the inverse monoids that arise from also considering their generalised inverses. this leads to well - known classic inverse monoids, as well as a novel inverse monoid ( the ' arithmetic inverse monoid ' a ) that generalises these in a natural number - theoretic manner. based on this, we interpret classic inverse semigroup theoretic concepts arithmetically, and vice versa. composition and normal forms within a are based on the chinese remainder theorem, and a minimal generating set corresponds to all prime - order polycyclic monoids. this then gives a close connection between nivat & perot ' s normal forms for polycyclic monoids, mixed - radix counting systems, and p - adic norms & distances. | arxiv:2206.07412 |
nuclear magnetic dipole properties of ground bands and gamma - vibrational bands are studied for the first time using the triaxial projected shell model approach. the study is carried out for the dy and er isotopic chains, ranging from transitional to well - deformed region. it is found that the g - factor ratio of the 2 ^ + state in ground bands to that of gamma - bands, r = g ( 2 ^ +, gamma - vib ) / g ( 2 ^ +, ground ), varies along an isotopic chain. with the gamma - deformations, which best reproduce the energy levels for both bands, we obtain a qualitative agreement with the experimental data. this result thus suggests that study of the ratio may provide an important information on the triaxial deformation of a nuclear system. the angular - momentum dependence of the ground band g - factor on the triaxial deformation is also investigated. | arxiv:nucl-th/0201087 |
multi - modal large language models ( mllms ) have recently exhibited impressive general - purpose capabilities by leveraging vision foundation models to encode the core concepts of images into representations. these are then combined with instructions and processed by the language model to generate high - quality responses. despite significant progress in enhancing the language component, challenges persist in optimally fusing visual encodings within the language model for task - specific adaptability. recent research has focused on improving this fusion through modality adaptation modules but at the cost of significantly increased model complexity and training data needs. in this paper, we propose emma ( efficient multi - modal adaptation ), a lightweight cross - modality module designed to efficiently fuse visual and textual encodings, generating instruction - aware visual representations for the language model. our key contributions include : ( 1 ) an efficient early fusion mechanism that integrates vision and language representations with minimal added parameters ( less than 0. 2 % increase in model size ), ( 2 ) an in - depth interpretability analysis that sheds light on the internal mechanisms of the proposed method ; ( 3 ) comprehensive experiments that demonstrate notable improvements on both specialized and general benchmarks for mllms. empirical results show that emma boosts performance across multiple tasks by up to 9. 3 % while significantly improving robustness against hallucinations. our code is available at https : / / github. com / saraghazanfari / emma | arxiv:2410.02080 |
options ( e. g., voting behavior, choice of a punishment for another participant ). reaction time. the time between the presentation of a stimulus and an appropriate response can indicate differences between two cognitive processes, and can indicate some things about their nature. for example, if in a search task the reaction times vary proportionally with the number of elements, then it is evident that this cognitive process of searching involves serial instead of parallel processing. psychophysical responses. psychophysical experiments are an old psychological technique, which has been adopted by cognitive psychology. they typically involve making judgments of some physical property, e. g. the loudness of a sound. correlation of subjective scales between individuals can show cognitive or sensory biases as compared to actual physical measurements. some examples include : sameness judgments for colors, tones, textures, etc. threshold differences for colors, tones, textures, etc. eye tracking. this methodology is used to study a variety of cognitive processes, most notably visual perception and language processing. the fixation point of the eyes is linked to an individual ' s focus of attention. thus, by monitoring eye movements, we can study what information is being processed at a given time. eye tracking allows us to study cognitive processes on extremely short time scales. eye movements reflect online decision making during a task, and they provide us with some insight into the ways in which those decisions may be processed. = = = brain imaging = = = brain imaging involves analyzing activity within the brain while performing various tasks. this allows us to link behavior and brain function to help understand how information is processed. different types of imaging techniques vary in their temporal ( time - based ) and spatial ( location - based ) resolution. brain imaging is often used in cognitive neuroscience. single - photon emission computed tomography and positron emission tomography. spect and pet use radioactive isotopes, which are injected into the subject ' s bloodstream and taken up by the brain. by observing which areas of the brain take up the radioactive isotope, we can see which areas of the brain are more active than other areas. pet has similar spatial resolution to fmri, but it has extremely poor temporal resolution. electroencephalography. eeg measures the electrical fields generated by large populations of neurons in the cortex by placing a series of electrodes on the scalp of the subject. this technique has an extremely high temporal resolution, but a relatively poor spatial resolution. functional magnetic resonance imaging. fmri measures the relative amount of oxygenated blood flowing to different parts of the brain. more oxygen | https://en.wikipedia.org/wiki/Cognitive_science |
we explore the energy dynamics of a two dimensional ( 2d ) harmonically trapped bose - einstein condensate inside a box potential, excited by a moving red - detuned laser potential ( rdlp ). for an rdlp velocity $ v $ less than a critical value $ v _ c $, energy oscillations are observed to begin simultaneously with the motion of the rdlp. for $ v > v _ c $, these oscillations are delayed through a transient in the energy. at the end of the delay time $ t _ { ons } $, the energy oscillations are regenerated again, and $ t _ { ons } $ is found to depend on $ v $ through universal relations for two cases : one for an rdlp depth sufficient to break off a bec fragment, another for a depth insufficient to split the bec. in the case of splitting, $ t _ { ons } $ exactly equals the time it takes the bec fragment ( dragged by the rdlp trough ) to reach the hard wall of the box potential. | arxiv:1110.6518 |
this article introduces a novel approach to the mean - field limit of stochastic systems of interacting particles, leading to the first ever derivation of the mean - field limit to the vlasov - poisson - fokker - planck system for plasmas in dimension ~ $ 2 $ together with a partial result in dimension ~ $ 3 $. the method is broadly compatible with second order systems that lead to kinetic equations and it relies on novel estimates on the bbgky hierarchy. by taking advantage of the diffusion in velocity, those estimates bound weighted $ l ^ p $ norms of the marginals or observables of the system, uniformly in the number of particles. this allows to qualitatively derive the mean - field limit for very singular interaction kernels between the particles, including repulsive poisson interactions, together with quantitative estimates for a general kernel in $ l ^ 2 $. | arxiv:2203.15747 |
we obtain vaidya - like solutions to include both a null fluid and a string fluid in non - spherical ( plane symmetric and cylindrical symmetric ) anti - de sitter space - times. assuming that string fluid diffuse, we find exact solutions of einstein ' s field equations. thus we extend a recent work of glass and krisch \ cite { gk } to non - spherical anti - de sitter space - times. | arxiv:gr-qc/0608035 |
knowledge editing techniques have emerged as essential tools for updating the factual knowledge of large language models ( llms ) and multimodal models ( lmms ), allowing them to correct outdated or inaccurate information without retraining from scratch. however, existing benchmarks for multimodal knowledge editing primarily focus on entity - level knowledge represented as simple triplets, which fail to capture the complexity of real - world multimodal information. to address this issue, we introduce mmke - bench, a comprehensive multimodal knowledge editing benchmark, designed to evaluate the ability of lmms to edit diverse visual knowledge in real - world scenarios. mmke - bench addresses these limitations by incorporating three types of editing tasks : visual entity editing, visual semantic editing, and user - specific editing. besides, mmke - bench uses free - form natural language to represent and edit knowledge, offering a more flexible and effective format. the benchmark consists of 2, 940 pieces of knowledge and 8, 363 images across 33 broad categories, with evaluation questions automatically generated and human - verified. we assess five state - of - the - art knowledge editing methods on three prominent lmms, revealing that no method excels across all criteria, and that visual and user - specific edits are particularly challenging. mmke - bench sets a new standard for evaluating the robustness of multimodal knowledge editing techniques, driving progress in this rapidly evolving field. | arxiv:2502.19870 |
besides vaccination, as an effective way to mitigate the further spread of covid - 19, fast and accurate screening of individuals to test for the disease is yet necessary to ensure public health safety. we propose covid - net uv, an end - to - end hybrid spatio - temporal deep neural network architecture, to detect covid - 19 infection from lung point - of - care ultrasound videos captured by convex transducers. covid - net uv comprises a convolutional neural network that extracts spatial features and a recurrent neural network that learns temporal dependence. after careful hyperparameter tuning, the network achieves an average accuracy of 94. 44 % with no false - negative cases for covid - 19 cases. the goal with covid - net uv is to assist front - line clinicians in the fight against covid - 19 via accelerating the screening of lung point - of - care ultrasound videos and automatic detection of covid - 19 positive cases. | arxiv:2205.08932 |
we present a time - lapse sequence of 20 near - infrared ( j - and k ' - band ) snapshots of the central 20x20 arcsec of the crab pulsar wind nebula, taken at subarcsecond resolution with the hokupa ' a / quirc adaptive optics camera on the gemini north telescope, and sampled at intervals of 10 min and 24 hr. it is observed that the equatorial wisps and polar knots in the termination shock of the pulsar wind appear to fluctuate in brightness on kilosecond time - scales. maximum flux variations of + / - 24 + / - 4 and + / - 14 + / - 4 per cent relative to the mean ( in 1. 2 ks ) are measured for the wisps and knots respectively, with greatest statistical significance in j band where the nebula background is less prominent. the j and k ' flux densities imply different near - infrared spectra for the nonthermal continuum emission from the wisps and outermost polar knot ( sprite ), giving f _ nu ~ nu ^ { - 0. 56 + / - 0. 12 } and f _ nu ~ nu ^ { - 0. 21 + / - 0. 13 ) respectively. the data are compared with existing optical and uv photometry and applied to constrain theories of the variability of the wisps ( relativistic ion - cyclotron instability ) and knots ( relativistic fire hose instability ). | arxiv:astro-ph/0509914 |
as an ideal platform to explore strong quantized light - matter interactions, surface plasmon polariton ( spp ) has inspired many applications in quantum technologies. it was recently found that quantum surface effects ( qses ) of the metal, including nonlocal optical response, electron spill - out, and landau damping, contribute additional loss sources to the spp. such a deteriorated loss of the spp severely hinders its realization of long - distance quantum interconnect. here, we investigate the non - markovian dynamics of quantum emitters ( qes ) coupled to a common spp in the presence of the qses in a planar metal - dielectric nanostructure. a mechanism to overcome the dissipation of the qes caused by the lossy spp is discovered. we find that, as long as the qe - spp bound states favored by the qses are formed, a dissipationless entanglement among the qes is created. it leads to that the separated qes are coherently correlated in a manner of the rabi - like oscillation mediated by the spp even experiencing the metal absorption. our study on the qses refreshes our understanding of the light - matter interactions in the absorptive medium and paves the way for applying the spp in quantum interconnect. | arxiv:2411.02990 |
cooperative behaviour has been extensively studied as a choice between cooperation and defection. however, the possibility to not participate is also frequently available. this type of problem can be studied through the optional public goods game. the introduction of the " loner " strategy, allows players to withdraw from the game, which leads to a cooperator - defector - loner cycle. while prosocial punishment can help increase cooperation, anti - social punishment - - where defectors punish cooperators - - causes its downfall in both experimental and theoretical studies. in this paper, we introduce social norms that allow agents to condition their behaviour to the reputation of their peers. we benchmark this both with respect to the standard optional public goods game and to the variant where all types of punishment are allowed. we find that a social norm imposing a more moderate reputational penalty for opting out than for defecting, increases cooperation. when, besides reputation, punishment is also possible, the two mechanisms work synergically under all social norms that do not assign to loners a strictly worse reputation than to defectors. under this latter setup, the high levels of cooperation are sustained by conditional strategies, which largely reduce the use of pro - social punishment and almost completely eliminate anti - social punishment. | arxiv:2110.02031 |
structure - preserving algorithms for solving conservative pdes with added linear dissipation are generalized to systems with time - dependent damping / driving terms. this study is motivated by several pde models of physical phenomena, such as korteweg - de vries, klein - gordon, schr \ " { o } dinger, and camassa - holm equations, all with damping / driving terms and time - dependent coefficients. since key features of the pdes under consideration are described by local conservation laws, which are independent of the boundary conditions, the proposed ( second - order in time ) discretizations are developed with the intent of preserving those local conservation laws. the methods are respectively applied to a damped - driven nonlinear schr \ " { o } dinger equation and a damped camassa - holm equation. numerical experiments illustrate the structure - preserving properties of the methods, as well as favorable results over other competitive schemes. | arxiv:1804.02266 |
sharing, an abstract domain developed by d. jacobs and a. langen for the analysis of logic programs, derives useful aliasing information. it is well - known that a commonly used core of techniques, such as the integration of sharing with freeness and linearity information, can significantly improve the precision of the analysis. however, a number of other proposals for refined domain combinations have been circulating for years. one feature that is common to these proposals is that they do not seem to have undergone a thorough experimental evaluation even with respect to the expected precision gains. in this paper we experimentally evaluate : helping sharing with the definitely ground variables found using pos, the domain of positive boolean formulas ; the incorporation of explicit structural information ; a full implementation of the reduced product of sharing and pos ; the issue of reordering the bindings in the computation of the abstract mgu ; an original proposal for the addition of a new mode recording the set of variables that are deemed to be ground or free ; a refined way of using linearity to improve the analysis ; the recovery of hidden information in the combination of sharing with freeness information. finally, we discuss the issue of whether tracking compoundness allows the computation of more sharing information. | arxiv:cs/0401022 |
in this article, we study a discounted stochastic game to model resource optimal intrusion detection in wireless sensor networks. to address the problem of uncertainties in various network parameters, we propose a globalized robust game theoretic framework for discounted robust stochastic games. a robust solution to the considered problem is an optimal point that is feasible for all realizations of data from a given uncertainty set. to allow a controlled violation of the constraints when the parameters move out of the uncertainty set, the concept of globalized robust framework comes into view. in this article, we formulate a globalized robust counterpart for the discounted stochastic game under consideration. with the help of globalized robust optimization, a concept of globalized robust markov perfect equilibrium is introduced. the existence of such an equilibrium is shown for a discounted stochastic game when the number of actions of the players is finite. the contraction mapping theorem, kakutani fixed point theorem and the concept of equicontinuity are used to prove the existence result. to compute a globalized robust markov perfect equilibrium for the considered discounted stochastic game, a tractable representation of the proposed globalized robust counterpart is also provided. using the derived tractable representation, we formulate a globalized robust intrusion detection system for wireless sensor networks. the simulation result reveals that the proposed globalized solution is much less sensitive to data perturbations than the robust solution. | arxiv:1909.11039 |
##l ( v ). a field automorphism is a bijective ring homomorphism from a field to itself. in the cases of the rational numbers ( q ) and the real numbers ( r ) there are no nontrivial field automorphisms. some subfields of r have nontrivial field automorphisms, which however do not extend to all of r ( because they cannot preserve the property of a number having a square root in r ). in the case of the complex numbers, c, there is a unique nontrivial automorphism that sends r into r : complex conjugation, but there are infinitely ( uncountably ) many " wild " automorphisms ( assuming the axiom of choice ). field automorphisms are important to the theory of field extensions, in particular galois extensions. in the case of a galois extension l / k the subgroup of all automorphisms of l fixing k pointwise is called the galois group of the extension. = = symmetry in representation theory = = = = = symmetry in quantum mechanics : bosons and fermions = = = in quantum mechanics, bosons have representatives that are symmetric under permutation operators, and fermions have antisymmetric representatives. this implies the pauli exclusion principle for fermions. in fact, the pauli exclusion principle with a single - valued many - particle wavefunction is equivalent to requiring the wavefunction to be antisymmetric. an antisymmetric two - particle state is represented as a sum of states in which one particle is in state | x ⟩ { \ displaystyle \ scriptstyle | x \ rangle } and the other in state | y ⟩ { \ displaystyle \ scriptstyle | y \ rangle } : | ψ ⟩ = x, y a ( x, y ) | x, y ⟩ { \ displaystyle | \ psi \ rangle = \ sum _ { x, y } a ( x, y ) | x, y \ rangle } and antisymmetry under exchange means that a ( x, y ) = −a ( y, x ). this implies that a ( x, x ) = 0, which is pauli exclusion. it is true in any basis, since unitary changes of basis keep antisymmetric matrices antisymmetric, although strictly speaking, the quantity a ( x, y ) is not a matrix but an antisymmetric rank - two tensor. conversely, if the diagonal quantities a | https://en.wikipedia.org/wiki/Symmetry_in_mathematics |
recently, observations of compact stars have provided new data of high accuracy which put strong constraints on the high - density behaviour of the equation of state of strongly interacting matter otherwise not accessible in terrestrial laboratories. the evidence for neutron stars with high mass ( m = 2. 1 + / - 0. 2 m _ sun for psr j0751 + 1807 ) and large radii ( r > 12 km for rx j1856 - 3754 ) rules out soft equations of state and has provoked a debate whether the occurence of quark matter in compact stars can be excluded as well. in this contribution it is shown that modern quantum field theoretical approaches to quark matter including color superconductivity and a vector meanfield allow a microscopic description of hybrid stars which fulfill the new, strong constraints. the deconfinement transition in the resulting stiff hybrid equation of state is weakly first order so that signals of it have to be expected due to specific changes in transport properties governing the rotational and cooling evolution caused by the color superconductivity of quark matter. a similar conclusion holds for the investigation of quark deconfinement in future generations of nucleus - nucleus collision experiments at low temperatures and high baryon densities such as cbm @ fair. | arxiv:0708.4216 |
the paper provides a comprehensive overview of modeling and pricing cyber insurance and includes clear and easily understandable explanations of the underlying mathematical concepts. we distinguish three main types of cyber risks : idiosyncratic, systematic, and systemic cyber risks. while for idiosyncratic and systematic cyber risks, classical actuarial and financial mathematics appear to be well - suited, systemic cyber risks require more sophisticated approaches that capture both network and strategic interactions. in the context of pricing cyber insurance policies, issues of interdependence arise for both systematic and systemic cyber risks ; classical actuarial valuation needs to be extended to include more complex methods, such as concepts of risk - neutral valuation and ( set - valued ) monetary risk measures. | arxiv:2209.07415 |
the problem of finding code distance has been long studied for the generic ensembles of linear codes and led to several algorithms that substantially reduce exponential complexity of this task. however, no asymptotic complexity bounds are known for distance verification in other ensembles of linear codes. our goal is to re - design the existing generic algorithms of distance verification and derive their complexity for ldpc codes. we obtain new complexity bounds with provable performance expressed in terms of the erasure - correcting thresholds of long ldpc codes. these bounds exponentially reduce complexity estimates known for linear codes. | arxiv:1605.02410 |
in our preceding serial works, we have investigated the generation of higher - order atomic dipole squeezing ( hoads ) in a high - q micromaser cavity, discussing the effects of dynamic stark shift, atomic damping, atomic coherence and nonlinear one - photon processes and different initial states ( for example, correlated and uncorrelated states, superposition states, squeezed vacuum ). in this paper, we continue to study hoads in a high - q micromaser cavity, but consider that the atom interacts with the optical field via a multi - photon transition process and that the initial atom is arbitrarily prepared. for a vacuum initial field, we demonstrate that hoads cannot occur if the atom is initially prepared in a chaotic state and that a coherent atomic state generates less efficient and stable hoads than an arbitrary one. it is found that large detuning may lead to enhanced and strong hoads. | arxiv:cond-mat/0301248 |
within a scotogenic neutrino mass model we explore the cogenesis of matter from the cp violating decay of a heavy $ \ mathbb { z } _ 2 $ - odd right handed neutrino that simultaneously populates the visible and a multipartite dark sector. the quantum of cp violation sets the baryon asymmetry in the visible sector driven by leptogenesis. the relic density of a sub - gev scale freeze - in dark matter is generated by the late time decay of the next to lightest dark particle dynamically regulated by its interplay with the thermal scattering processes. | arxiv:2409.06541 |
a recent approach for few - shot text classification is to convert textual inputs to cloze questions that contain some form of task description, process them with a pretrained language model and map the predicted words to labels. manually defining this mapping between words and labels requires both domain expertise and an understanding of the language model ' s abilities. to mitigate this issue, we devise an approach that automatically finds such a mapping given small amounts of training data. for a number of tasks, the mapping found by our approach performs almost as well as hand - crafted label - to - word mappings. | arxiv:2010.13641 |
in leptophilic scenarios, dark matter interactions with nuclei, relevant for direct detection experiments and for the capture by celestial objects, could only occur via loop - induced processes. if the mediator is a scalar or pseudo - scalar particle, which only couples to leptons, the dominant contribution to dark matter - nucleus scattering would take place via two - photon exchange with a lepton triangle loop. the corresponding diagrams have been estimated in the literature under different approximations. here, we present new analytical calculations for one - body two - loop and two - body one - loop interactions. the two - loop form factors are presented in closed analytical form in terms of generalized polylogarithms up to weight four. in both cases, we consider the exact dependence on all the involved scales, and study the dependence on the momentum transfer. we show that some previous approximations fail to correctly predict the scattering cross section by several orders of magnitude. moreover, we show that form factors, in the range of momentum transfer relevant for local galactic dark matter, are smaller than their value at zero momentum transfer, which is usually considered. | arxiv:2105.12116 |
we study the problem of the rigorous derivation of one - dimensional models for a thin curved beam starting from three - dimensional nonlinear elasticity. we describe the limiting models obtained for different scalings of the energy. in particular, we prove that the limit functional corresponding to higher scalings coincides with the one derived by dimension reduction starting from linearized elasticity. finally we also address the case of thin elastic rings. | arxiv:0803.0927 |
the closure of a discrete exponential family is described by a finite set of equations corresponding to the circuits of an underlying oriented matroid. these equations are similar to the equations used in algebraic statistics, although they need not be polynomial in the general case. this description allows for a combinatorial study of the possible support sets in the closure of an exponential family. if two exponential families induce the same oriented matroid, then their closures have the same support sets. furthermore, the positive cocircuits give a parameterization of the closure of the exponential family. | arxiv:0906.5462 |
the universe is found to have undergone several phases in which the gravitational constant had different behaviors. during some epochs the energy density of the universe remained constant and the universe remained static. in the radiation dominated epoch the radiation field satisfies stefan ' s formula while the scale factor varies linearly with time. the model enhances the formation of the structure in the universe as observed today. | arxiv:astro-ph/9911311 |
in the present paper we shall investigate the waring ' s problem for upper triangular matrix algebras. the main result is the following : let $ n \ geq 2 $ and $ m \ geq 1 $ be integers. let $ p ( x _ 1, \ ldots, x _ m ) $ be a noncommutative polynomial with zero constant term over an infinite field $ k $. let $ t _ n ( k ) $ be the set of all $ n \ times n $ upper triangular matrices over $ k $. suppose $ 1 < r < n - 1 $, where $ r $ is the order of $ p $. we have that $ p ( t _ n ( k ) ) + p ( t _ n ( k ) ) = j ^ r $, where $ j $ is the jacobson radical of $ t _ n ( k ) $. if $ r = n - 2 $, then $ p ( t _ n ( k ) ) = j ^ { n - 2 } $. this gives a definitive solution of a conjecture proposed by panja and prasad. | arxiv:2306.15118 |
we propose minvis, a minimal video instance segmentation ( vis ) framework that achieves state - of - the - art vis performance with neither video - based architectures nor training procedures. by only training a query - based image instance segmentation model, minvis outperforms the previous best result on the challenging occluded vis dataset by over 10 % ap. since minvis treats frames in training videos as independent images, we can drastically sub - sample the annotated frames in training videos without any modifications. with only 1 % of labeled frames, minvis outperforms or is comparable to fully - supervised state - of - the - art approaches on youtube - vis 2019 / 2021. our key observation is that queries trained to be discriminative between intra - frame object instances are temporally consistent and can be used to track instances without any manually designed heuristics. minvis thus has the following inference pipeline : we first apply the trained query - based image instance segmentation to video frames independently. the segmented instances are then tracked by bipartite matching of the corresponding queries. this inference is done in an online fashion and does not need to process the whole video at once. minvis thus has the practical advantages of reducing both the labeling costs and the memory requirements, while not sacrificing the vis performance. code is available at : https : / / github. com / nvlabs / minvis | arxiv:2208.02245 |
we propose a phenomenological approach to examine the role of short - and long - range nucleon - nucleon correlations in the quenching of single - particle strength in atomic nuclei and their evolution in asymmetric nuclei and neutron matter. these correlations are thought to be the reason for the quenching of spectroscopic factors observed in $ \ rm ( e, e ' p ) $, $ \ rm ( p, 2p ) $ and transfer reactions. we show that the recently observed increase of the high - momentum component of the protons in neutron - rich nuclei is consistent with the reduced proton spectroscopic factors. our approach connects recent results on short - range correlations from high - energy electron scattering experiments with the quenching of spectroscopic factors and addresses for the first time quantitatively this intriguing question in nuclear physics, in particular regarding its isospin dependence. we also speculate about the nature of a { \ sl quasi - proton } ( nuclear polaron ) in neutron matter and its kinetic energy, an important quantity for the properties of neutron stars. | arxiv:1812.08051 |
the heisenberg curve is defined to be the curve corresponding to an extension of the projective line by the heisenberg group modulo $ n $, ramified above three points. this curve is related to the fermat curve and its group of automorphisms is studied. also we give an explicit equation for the curve $ c _ 3 $. | arxiv:1912.00390 |
aging experiments of a novel type of large area mcp - pmt made by juno collaboration were conducted. in these aging experiments, the multi - photoelectron spectrum and single photoelectron spectrum were measured daily, as well as the mcp resistance of the second pmt before and after the experiment. two pmts were aged successivelyfor cross check. the first pmt was aged for 52 days, while the other one was aged for 84 days. in order to study the mechanism of the aging process, the high voltage on the second pmt was increased to accelerate its aging process when the cumulative output of charge from its anode was about 4 c. from our study, it can be known that large area mcp - pmt aging had a strong relationship with the related mcps. in accordance with the pmt aging curve, a pmt aging model was setup and a general aging formula was given. | arxiv:1503.02497 |
interaction networks, consisting of agents linked by their interactions, are ubiquitous across many disciplines of modern science. many methods of analysis of interaction networks have been proposed, mainly concentrating on node degree distribution or aiming to discover clusters of agents that are very strongly connected between themselves. these methods are principally based on graph - theory or machine learning. we present a mathematically simple formalism for modelling context - specific information propagation in interaction networks based on random walks. the context is provided by selection of sources and destinations of information and by use of potential functions that direct the flow towards the destinations. we also use the concept of dissipation to model the aging of information as it diffuses from its source. using examples from yeast protein - protein interaction networks and some of the histone acetyltransferases involved in control of transcription, we demonstrate the utility of the concepts and the mathematical constructs introduced in this paper. | arxiv:1112.3988 |
tube formulas ( by which we mean an explicit formula for the volume of an $ \ epsilon $ - neighbourhood of a subset of a suitable metric space ) have been used in many situations to study properties of the subset. for smooth submanifolds of euclidean space, this includes weyl ' s celebrated results on spectral asymptotics, and the subsequent relation between curvature and spectrum. additionally, a tube formula contains information about the dimension and measurability of rough sets. in convex geometry, the tube formula of a convex subset of euclidean space allows for the definition of certain curvature measures. these measures describe the curvature of sets which are not too irregular to support derivatives. in this survey paper, we describe some recent advances in the development of tube formulas for self - similar fractals, and their applications and connections to the other topics mentioned here. | arxiv:0711.0173 |
stromgren synthetic photometry from an empirically calibrated grid of stellar atmosphere models has been used to derive the effective temperature of each component of double lined spectroscopic ( sb2 ) eclipsing binaries. for this purpose, we have selected a sub - sample of 20 sb2s for which b - y, m _ 1, and c _ 1 individual indices are available. this new determination of effective temperature has been performed in a homogeneous way for all these stars. as the effective temperature determination is related to the assumed metallicity, we explore simultaneous solutions in the ( teff, [ fe / h ] ) - plane and present our results as confidence regions computed to match the observed values of surface gravity, b - y, m _ 1, and c _ 1, taking into account interstellar reddening. these confidence regions show that previous estimates of teff are often too optimistic, and that [ fe / h ] should not be neglected in such determinations. comparisons with ribas et al. ( 1998 ) using hipparcos parallaxes are also presented for 8 binaries of our working sample, showing good agreement with the most reliable parallaxes. this point gives a significant weight to the validity of the basel models for synthetic photometry applications. | arxiv:astro-ph/9811103 |
shunt facts devices, such as, a static var compensator ( svc ), are capable of providing local reactive power compensation. they are widely used in the network to reduce the real power loss and improve the voltage profile. this paper proposes a planning model based on mixed integer conic programming ( micp ) to optimally allocate svcs in the transmission network considering load uncertainty. the load uncertainties are represented by a number of scenarios. reformulation and linearization techniques are utilized to transform the original non - convex model into a convex second order cone programming ( socp ) model. numerical case studies based on the ieee 30 - bus system demonstrate the effectiveness of the proposed planning model. | arxiv:1703.09854 |
we study the quantization of abelian gauge theories of principal torus bundles over compact manifolds with and without boundary. it is shown that these gauge theories suffer from a gribov ambiguity originating in the non - triviality of the bundle of connections whose geometrical structure will be analyzed in detail. motivated by the stochastic quantization approach we propose a modified functional integral measure on the space of connections that takes the gribov problem into account. this functional integral measure is used to calculate the partition function, the greens functions and the field strength correlating functions in any dimension using the fact that the space of inequivalent connections itself admits the structure of a bundle over a finite dimensional torus. the greens functions are shown to be affected by the non - trivial topology, giving rise to non - vanishing vacuum expectation values for the gauge fields. | arxiv:0707.1186 |
visual artifacts remain a persistent challenge in diffusion models, even with training on massive datasets. current solutions primarily rely on supervised detectors, yet lack understanding of why these artifacts occur in the first place. in our analysis, we identify three distinct phases in the diffusion generative process : profiling, mutation, and refinement. artifacts typically emerge during the mutation phase, where certain regions exhibit anomalous score dynamics over time, causing abrupt disruptions in the normal evolution pattern. this temporal nature explains why existing methods focusing only on spatial uncertainty of the final output fail at effective artifact localization. based on these insights, we propose asced ( abnormal score correction for enhancing diffusion ), that detects artifacts by monitoring abnormal score dynamics during the diffusion process, with a trajectory - aware on - the - fly mitigation strategy that appropriate generation of noise in the detected areas. unlike most existing methods that apply post hoc corrections, \ eg, by applying a noising - denoising scheme after generation, our mitigation strategy operates seamlessly within the existing diffusion process. extensive experiments demonstrate that our proposed approach effectively reduces artifacts across diverse domains, matching or surpassing existing supervised methods without additional training. | arxiv:2503.16218 |
the success of semi - supervised manifold learning is highly dependent on the quality of the labeled samples. active manifold learning aims to select and label representative landmarks on a manifold from a given set of samples to improve semi - supervised manifold learning. in this paper, we propose a novel active manifold learning method based on a unified framework of manifold landmarking. in particular, our method combines geometric manifold landmarking methods with algebraic ones. we achieve this by using the gershgorin circle theorem to construct an upper bound on the learning error that depends on the landmarks and the manifold ' s alignment matrix in a way that captures both the geometric and algebraic criteria. we then attempt to select landmarks so as to minimize this bound by iteratively deleting the gershgorin circles corresponding to the selected landmarks. we also analyze the complexity, scalability, and robustness of our method through simulations, and demonstrate its superiority compared to existing methods. experiments in regression and classification further verify that our method performs better than its competitors. | arxiv:1710.09334 |
airborne insects generate a leading edge vortex when they flap their wings. this coherent vortex is a low pressure region that enhances the lift of flapping wings compared to fixed wings. insect wings are thin membranes strengthened by a system of veins that does not allow large wing deformations. bat wings are thin compliant skin membranes stretched between their limbs, hand, and body that show larger deformations during flapping wing flight. this study examines the role of the leading edge vortex on highly deformable membrane wings that passively change shape under fluid dynamic loading maintaining a positive camber throughout the hover cycle. our experiments reveal that unsteady wing deformations suppress the formation of a coherent leading edge vortex as flexibility increases. at lift and energy optimal aeroelastic conditions, there is no more leading edge vortex. instead, vorticity accumulates in a bound shear layer covering the wing ' s upper surface from the leading to the trailing edge. despite the absence of a leading edge vortex, the optimal deformable membrane wings demonstrate enhanced lift and energy efficiency compared to their rigid counterparts. it is possible that small bats rely on this mechanism for efficient hovering. we relate the force production on the wings with their deformation through scaling analyses. additionally, we identify the geometric angles at the leading and trailing edges as observable indicators of the flow state and use them to map out the transitions of the flow topology and their aerodynamic performance for a wide range of aeroelastic conditions. | arxiv:2410.01670 |
augmented lagrangian ( al ) methods are a well known class of algorithms for solving constrained optimization problems. they have been extended to the solution of saddle - point systems of linear equations. we study an al ( spal ) algorithm for unsymmetric saddle - point systems and derive convergence and semi - convergence properties, even when the system is singular. at each step, our spal requires the exact solution of a linear system of the same size but with an spd ( 2, 2 ) block. to improve efficiency, we introduce an inexact spal algorithm. we establish its convergence properties under reasonable assumptions. specifically, we use a gradient method, known as the barzilai - borwein ( bb ) method, to solve the linear system at each iteration. we call the result the augmented lagrangian bb ( spalbb ) algorithm and study its convergence. numerical experiments on test problems from navier - stokes equations and coupled stokes - darcy flow show that spalbb is more robust and efficient than bicgstab and gmres. spalbb often requires the least cpu time, especially on large systems. | arxiv:2404.14636 |
a significant challenge for brain histological data analysis is to precisely identify anatomical regions in order to perform accurate local quantifications and evaluate therapeutic solutions. usually, this task is performed manually, becoming therefore tedious and subjective. another option is to use automatic or semi - automatic methods, among which segmentation using digital atlases co - registration. however, most available atlases are 3d, whereas digitized histological data are 2d. methods to perform such 2d - 3d segmentation from an atlas are required. this paper proposes a strategy to automatically and accurately segment single 2d coronal slices within a 3d volume of atlas, using linear registration. we validated its robustness and performance using an exploratory approach at whole - brain scale. | arxiv:2111.08705 |
the replacement of bulk refractive optical elements with diffractive planar components enables the miniaturization of optical systems. however, diffractive optics suffers from large chromatic aberrations due to the dispersion of the phase accumulated by light during propagation. we show that this limitation can be overcome with an engineered wavelength - dependent phase shift imparted by a metasurface and demonstrate a design that deflects three wavelengths without dispersion. a planar lens without chromatic aberrations at three wavelengths is also presented. our design is based on low - loss dielectric resonators which introduce a dense spectrum of optical modes to enable dispersive phase compensation. the suppression of chromatic aberrations in metasurface - based planar photonics will find applications in lightweight collimators for displays, and chromatically - corrected imaging systems. | arxiv:1411.3966 |
recently deep learning has been successfully applied to unsupervised active learning. however, current method attempts to learn a nonlinear transformation via an auto - encoder while ignoring the sample relation, leaving huge room to design more effective representation learning mechanisms for unsupervised active learning. in this paper, we propose a novel deep unsupervised active learning model via learnable graphs, named allg. allg benefits from learning optimal graph structures to acquire better sample representation and select representative samples. to make the learnt graph structure more stable and effective, we take into account $ k $ - nearest neighbor graph as a priori, and learn a relation propagation graph structure. we also incorporate shortcut connections among different layers, which can alleviate the well - known over - smoothing problem to some extent. to the best of our knowledge, this is the first attempt to leverage graph structure learning for unsupervised active learning. extensive experiments performed on six datasets demonstrate the efficacy of our method. | arxiv:2111.04286 |
we discuss the electroweak gauge symmetry breaking triggered by a new strong attractive interaction to condensate fermion - antifermion, and topcolor is a prototype. to deal with the fermion pairing, a general method based on the hubbard - stratonovich transformation in the functional integral approach is used. we derive a formula which relates the $ w ^ \ pm $, $ z ^ 0 $ weak boson masses to that of the condensated fermion, thus generalizing the pagels - stokar formula obtained in qcd. the custodial su ( 2 ) electroweak symmetry turns out to be systematically violated, the deviation of $ \ rho \ equiv m _ w ^ 2 / ( m _ z ^ 2 \ cos ^ 2 \ theta _ w ) $ from unity is related to the new physics scale $ \ lambda $. some phenomenological consequences of the top - pair condensation models are discussed. distinctive signatures of the $ \ bar { t } t $ scalar bound state, a higgs boson like denoted by $ h _ t $, are the dominant decay modes $ h _ t \ to \ upsilon + \ gamma, $ $ h _ t \ to \ upsilon + z ^ 0 $, and $ h _ t \ to b ^ * + \ bar { b } ^ * $. | arxiv:hep-ph/9910430 |
{ 1 } { 0 } } } is well - formed, but it is not well - defined. ( see division by zero ). such expressions are called undefined. = = = well - defined = = = semantics is the study of meaning. formal semantics is about attaching meaning to expressions. an expression that defines a unique value or meaning is said to be well - defined. otherwise, the expression is said to be ill defined or ambiguous. in general the meaning of expressions is not limited to designating values ; for instance, an expression might designate a condition, or an equation that is to be solved, or it can be viewed as an object in its own right that can be manipulated according to certain rules. certain expressions that designate a value simultaneously express a condition that is assumed to hold, for instance those involving the operator ⊕ { \ displaystyle \ oplus } to designate an internal direct sum. in algebra, an expression may be used to designate a value, which might depend on values assigned to variables occurring in the expression. the determination of this value depends on the semantics attached to the symbols of the expression. the choice of semantics depends on the context of the expression. the same syntactic expression 1 + 2 × 3 can have different values ( mathematically 7, but also 9 ), depending on the order of operations implied by the context ( see also operations § calculators ). for real numbers, the product a × b × c { \ displaystyle a \ times b \ times c } is unambiguous because ( a × b ) × c = a × ( b × c ) { \ displaystyle ( a \ times b ) \ times c = a \ times ( b \ times c ) } ; hence the notation is said to be well defined. this property, also known as associativity of multiplication, guarantees the result does not depend on the sequence of multiplications ; therefore, a specification of the sequence can be omitted. the subtraction operation is non - associative ; despite that, there is a convention that a − b − c { \ displaystyle a - b - c } is shorthand for ( a − b ) − c { \ displaystyle ( a - b ) - c }, thus it is considered " well - defined ". on the other hand, division is non - associative, and in the case of a / b / c { \ displaystyle a / b / c }, parenthesization conventions are not well | https://en.wikipedia.org/wiki/Expression_(mathematics) |
together with the recent advances in semantic segmentation, many domain adaptation methods have been proposed to overcome the domain gap between training and deployment environments. however, most previous studies use limited combinations of source / target datasets, and domain adaptation techniques have never been thoroughly evaluated in a more challenging and diverse set of target domains. this work presents a new multi - domain dataset driv100 for benchmarking domain adaptation techniques on in - the - wild road - scene videos collected from the internet. the dataset consists of pixel - level annotations for 100 videos selected to cover diverse scenes / domains based on two criteria ; human subjective judgment and an anomaly score judged using an existing road - scene dataset. we provide multiple manually labeled ground - truth frames for each video, enabling a thorough evaluation of video - level domain adaptation where each video independently serves as the target domain. using the dataset, we quantify domain adaptation performances of state - of - the - art methods and clarify the potential and novel challenges of domain adaptation techniques. the dataset is available at https : / / doi. org / 10. 5281 / zenodo. 4389243. | arxiv:2102.00150 |
a model using wake oscillators is developed to predict the 2d motion in a transverse plan of two rigid cylinders in tandem arrangement. this model of the wake dynamics is validated with experimental data from previous trials which took place at the ifremer flume tank in boulogne - sur - mer, france. the agreement between the model and the experimental results allows using this model as a simple computational tool in the prediction of 2d vortex - induced vibrations ( viv ) and, after some futher developments, wake - induced oscillations ( wio ) effects. | arxiv:1002.3596 |
we study particle - scale motion in sheared highly polydisperse amorphous materials, in which the largest particles are as much as ten times the size of the smallest. we find strikingly different behavior from the more commonly studied amorphous systems with low polydispersity. in particular, analysis of the nonaffine motion of particles reveals qualitative differences between large and small particles : the smaller particles have dramatically more nonaffine motion, which is induced by the presence of the large particles. we characterize the crossover in nonaffine motion from the low - to high - polydispersity regime, and demonstrate a quantitative way to distinguish between " large " and " small " particles in systems with broad distributions of particle sizes. | arxiv:2202.13045 |
the beams of linear collider after main collision can be utilized to build neutrino factory with exceptional parameters. we also discuss briefly possible applications of some elements of proposed scheme for standard fixed target experiments, new experiments with \ nu _ \ mu n interactions and in material sciences. | arxiv:hep-ph/0507335 |
feedback from star formation is a critical component of the evolution of galaxies and their interstellar medium. at parsec scales internal to molecular clouds, however, the observed signatures of that feedback on the physical properties of co - emitting gas have often been weak or inconclusive. we present sub - parsec observations of h2co in the 30 doradus region, which contains the massive star cluster r136 that is clearly exerting feedback on its neighboring gas. h2co provides a direct measure of gas kinetic temperature, and we find a trend of decreasing temperature with projected distance from r136 that may be indicative of gas heating by the stars. while it has been suggested that mechanical heating affects h2co - measured temperature, we do not observe any correlation between tk and line width. the lack of an enhancement in mechanical feedback close to r136 is consistent with the absence of a radial trend in gravitational boundedness seen the alma co observations. estimates of cosmic ray flux in the region are quite uncertain but can plausibly explain the observed temperatures, if r136 itself is the dominant local source of energetic protons. the observations presented here are also consistent with the h2co - emitting gas near r136 being dominated by direct radiation from r136 and photoelectric heating in the photodissociation regions. | arxiv:2405.07931 |
we consider the numerical approximation of the inertial landau - lifshitz - gilbert equation ( illg ), which describes the dynamics of the magnetization in ferromagnetic materials at subpicosecond time scales. we propose and analyze two fully discrete numerical schemes : the first method is based on a reformulation of the problem as a linear constrained variational formulation for the linear velocity. the second method exploits a reformulation of the problem as a first order system in time for the magnetization and the angular momentum. both schemes are implicit, based on first - order finite elements, and generate approximations satisfying the unit - length constraint of illg at the vertices of the underlying mesh. for both methods, we prove convergence of the approximations towards a weak solution of the problem. numerical experiments validate the theoretical results and show the applicability of the methods for the simulation of ultrafast magnetic processes. | arxiv:2103.09888 |
robust feature matching forms the backbone for most visual simultaneous localization and mapping ( vslam ), visual odometry, 3d reconstruction, and structure from motion ( sfm ) algorithms. however, recovering feature matches from texture - poor scenes is a major challenge and still remains an open area of research. in this paper, we present a stereo visual odometry ( stereovo ) technique based on point and line features which uses a novel feature - matching mechanism based on an attention graph neural network that is designed to perform well even under adverse weather conditions such as fog, haze, rain, and snow, and dynamic lighting conditions such as nighttime illumination and glare scenarios. we perform experiments on multiple real and synthetic datasets to validate the ability of our method to perform stereovo under low visibility weather and lighting conditions through robust point and line matches. the results demonstrate that our method achieves more line feature matches than state - of - the - art line matching algorithms, which when complemented with point feature matches perform consistently well in adverse weather and dynamic lighting conditions. | arxiv:2308.01125 |
euso - spb1 was released on april 24th, 2017, from the nasa balloon launch site in wanaka ( new zealand ) and landed on the south pacific ocean on may 7th. the data collected by the instruments onboard the balloon were analyzed to search uv pulse signatures of uhecr ( ultra high energy cosmic rays ) air showers. indirect measurements of uhecrs can be affected by cloud presence during nighttime, therefore it is crucial to know the meteorological conditions during the observation period of the detector. during the flight, the onboard euso - spb1 ucirc camera ( university of chicago infra - red camera ), acquired images in the field of view of the uv telescope. the available nighttime and daytime images include information on meteorological conditions of the atmosphere observed in two infra - red bands. the presence of clouds has been investigated employing a method developed to provide a dense cloudiness map for each available infra - red image. the final masks are intended to give pixel cloudiness information at the ir - camera pixel resolution that is nearly 4 - times higher than the one of the uv - camera. in this work, cloudiness maps are obtained by using an expert system based on the analysis of different low - level image features. furthermore, an image enhancement step was needed to be applied as a preprocessing step to deal with uncalibrated data. | arxiv:1909.05917 |
we investigate possible topological superconductivity in the kondo - kitaev model on the honeycomb lattice, where the kitaev spin liquid is coupled to conduction electrons via the kondo coupling. we use the self - consistent abrikosov - fermion mean - field theory to map out the phase diagram. upon increasing the kondo coupling, a first order transition occurs from the decoupled phase of spin liquid and conduction electrons to a ferromagnetic topological superconductor of class d with a single chiral majorana edge mode. this is followed by a second order transition into a paramagnetic topological superconductor of class diii with a single helical majorana edge mode. these findings offer a novel route to topological superconductivity in the kondo lattice system. we discuss the connection between topological nature of the kitaev spin liquid and topological superconductors obtained in this model. | arxiv:1804.10212 |
we compare element and isotopic fractionations measured in solar wind samples collected by nasa ' s genesis mission with those predicted from models incorporating both the ponderomotive force in the chromosphere and conservation of the first adiabatic invariant in the low corona. generally good agreement is found, suggesting that these factors are consistent with the process of solar wind fractionation. based on bulk wind measurements, we also consider in more detail the isotopic and elemental abundances of o. we find mild support for an o abundance in the range 8. 75 - 8. 83, with a value as low as 8. 69 disfavored. a stronger conclusion must await solar wind regime specific measurements from the genesis samples. | arxiv:1711.07503 |
it is shown that the manner of introducing theinteraction between a spin 1 particle and external classical gravitational field can be successfully uni - fied with the approach that occurred with regard to a spin 1 / 2 particle and was first developed by tetrode, weyl, fock, ivanenko. on that way a general - ly relativistical duffin - kemmer equation is costructed. so, the manner of extending the flat space dirac equation to general relativity case indicates clearly that the lorentz group underlies equally both these theories. in other words, the lorentz group retains its importance and significance at changing the minkowski space model to an arbitrary curved space - time. in contrast to this, at generalizing the proca formulation, we automatically destroy any relations to the lorentz group, although the definition itself for a spin 1 particle as an elementary object was based on just this group. such a gravity ' s sensitiveness to the fermion - boson division might appear rather strange and unattractive asymmetry, being subjected to the criticism. moreover, just this feature has brought about a plenty of speculation on this matter. in any case, this peculiarity of particle - gravity field inter - action is recorded almost in every handbook. in the paper, on the base of the duffin - kemmer formalism developed, the problem of a vector particle in the abelian monopole potential is considered. | arxiv:quant-ph/9812007 |
deep learning - based end - to - end automatic speech recognition ( asr ) has made significant strides but still struggles with performance on out - of - domain samples due to domain shifts in real - world scenarios. test - time adaptation ( tta ) methods address this issue by adapting models using test samples at inference time. however, current asr tta methods have largely focused on non - continual tta, which limits cross - sample knowledge learning compared to continual tta. in this work, we first propose a fast - slow tta framework for asr that leverages the advantage of continual and non - continual tta. following this framework, we introduce dynamic suta ( dsuta ), an entropy - minimization - based continual tta method for asr. to enhance dsuta robustness for time - varying data, we design a dynamic reset strategy to automatically detect domain shifts and reset the model, making it more effective at handling multi - domain data. our method demonstrates superior performance on various noisy asr datasets, outperforming both non - continual and continual tta baselines while maintaining robustness to domain changes without requiring domain boundary information. | arxiv:2406.11064 |
in this paper we generalize the martingale of kella and whitt to the setting of l \ ' { e } vy - type processes and show that the ( local ) martingales obtained are in fact square integrable martingales which upon dividing by the time index converge to zero a. s. and in $ l ^ 2 $. the reflected l \ ' { e } vy - type process is considered as an example. | arxiv:1210.2209 |
in the pursuit of room temperature quantum hardware, our study introduces a gate voltage tunable quantum wire within a tri - gated n - type junctionless mosfet. the application of gate voltage alters the parabolic potential well of the tri - gated junctionless mosfet, enabling modification of the nanowire ' s potential well profile. in the presence of light, photogenerated electrons accumulate at the center of the junctionless nanowire, aligning with the modified potential well profile influenced by gate bias. these carriers at the center are far from interfaces and experience less interfacial noise. therefore, such clean photo - doping shows clear, repeatable peaks in current for specific gate biases compared to the dark condition, considering different operating drain - to - source voltages at room temperature. we propose that photodoping - induced subband occupation of gate tunable potential well of the nanowire is the underlying phenomenon responsible for this kind of observation. this study reveals experimental findings demonstrating gate - induced switching from semi - classical to the quantum domain, followed by the optical occupancy of electronic sub - bands at room temperature. we developed a compact model based on the nonequilibrium green ' s function formalism to understand this phenomenon in our illuminated device better. this work reveals the survival of the quantum confinement effect at room temperature in such semi - classical transport. | arxiv:2403.07324 |
we produce several families of solutions for two - component nonlinear schr \ " { o } dinger / gross - pitaevskii equations. these include domain walls and the first example of an antidark or gray soliton in the one component, bound to a bright or dark soliton in the other. most of these solutions are linearly stable in their entire domain of existence. some of them are relevant to nonlinear optics, and all to bose - einstein condensates ( becs ). in the latter context, we demonstrate robustness of the structures in the presence of parabolic and periodic potentials ( corresponding, respectively, to the magnetic trap and optical lattices in becs ). | arxiv:cond-mat/0312176 |
the main objective of this article is to study the effect of spherical geometry on dynamic transitions and pattern formation for the rayleigh - benard convection. the study is mainly motivated by the importance of spherical geometry and convection in geophysical flows. it is shown in particular that the system always undergoes a continuous ( type - i ) transition to a $ 2l _ c $ - dimensional sphere $ s ^ { 2lc } $, where lc is the critical wave length corresponding to the critical rayleigh number. furthermore, it has shown in [ 12 ] that it is critical to add nonisotropic turbulent friction terms in the momentum equation to capture the large - scale atmospheric and oceanic circulation patterns. we show in particular that the system with turbulent friction terms added undergoes the same type of dynamic transition, and obtain an explicit formula linking the critical wave number ( pattern selection ), the aspect ratio, and the ratio between the horizontal and vertical turbulent friction coefficients. | arxiv:1110.5821 |
we present a new wavelet based method for the denoising of { \ it event related potentials } erps ), employing techniques recently developed for the paradigm of deterministic chaotic systems. the denoising scheme has been constructed to be appropriate for short and transient time sequences using circular state space embedding. its effectiveness was successfully tested on simulated signals as well as on erps recorded from within a human brain. the method enables the study of individual erps against strong ongoing brain electrical activity. | arxiv:physics/0001069 |
recently, work in nlp has shifted to few - shot ( in - context ) learning, with large language models ( llms ) performing well across a range of tasks. however, while fairness evaluations have become a standard for supervised methods, little is known about the fairness of llms as prediction systems. further, common standard methods for fairness involve access to models weights or are applied during finetuning, which are not applicable in few - shot learning. do llms exhibit prediction biases when used for standard nlp tasks? in this work, we explore the effect of shots, which directly affect the performance of models, on the fairness of llms as nlp classification systems. we consider how different shot selection strategies, both existing and new demographically sensitive methods, affect model fairness across three standard fairness datasets. we discuss how future work can include llm fairness evaluations. | arxiv:2311.08472 |
color ( or categorical ) range reporting is a variant of the orthogonal range reporting problem in which every point in the input is assigned a \ emph { color }. while the answer to an orthogonal point reporting query contains all points in the query range $ q $, the answer to a color reporting query contains only distinct colors of points in $ q $. in this paper we describe an o ( n ) - space data structure that answers one - dimensional color reporting queries in optimal $ o ( k + 1 ) $ time, where $ k $ is the number of colors in the answer and $ n $ is the number of points in the data structure. our result can be also dynamized and extended to the external memory model. | arxiv:1306.5029 |
brown and mallik ( bm ) recently showed that, for hot sources, recombination of non - thermal electrons ( ntr ) onto highly ionised heavy ions is not negligible compared to non - thermal bremsstrahlung ( ntb ) as a source of flare hard x - rays ( hxrs ) and so should be included in modelling non - thermal hxr flare emission. in view of major discrepancies between bm results for the thermal continua and those of the chianti code and of rhessi solar data, we critically re - examine and correct the bm analysis and modify the conclusions concerning the importance of ntr. although the analytic kramers expression used by bm is correct for the purely hydrogenic recombination cross section, the heuristic expressions used by bm to extend the kramers expression beyond the ` bare nucleus ' case to which it applies had serious errors. bm results have therefore been recalculated using corrected expressions, which have been validated against the results of detailed calculations. at t ~ 10 - 30 mk the dominant ions are fe 22 +, 23 +, 24 + for which bm erroneously overestimated ntr emission by around an order of magnitude. contrary to the bm claim, ntr in hot flare plasmas does not dominate over ntb, although in some cases it can be comparable and so still very important in inversions of photon spectra to derive electron spectra, especially as ntr includes sharp edge features. the bm claim of dominance of ntr over ntb in deka - kev emission is incorrect due to a serious error in their analysis. however, the ntr contribution can still be large enough to demand inclusion in spectral fitting, the spectral edges having potentially serious effects on inversion of hxr spectra to infer fast electron spectra. | arxiv:0912.3385 |
in this paper we investigate the properties of small surfaces of willmore type in riemannian manifolds. by \ emph { small } surfaces we mean topological spheres contained in a geodesic ball of small enough radius. in particular, we show that if there exist such surfaces with positive mean curvature in the geodesic ball $ b _ r ( p ) $ for arbitrarily small radius $ r $ around a point $ p $ in the riemannian manifold, then the scalar curvature must have a critical point at $ p $. as a byproduct of our estimates we obtain a strengthened version of the non - existence result of mondino \ cite { mondino : 2008 } that implies the non - existence of certain critical points of the willmore functional in regions where the scalar curvature is non - zero. | arxiv:0909.0590 |
with a resonant amplitude - modulation field on two rydberg atoms, we propose a rydberg antiblockade ( rab ) regime, where the rabi oscillation between collective ground and excited states is induced. a controlled - z gate can be yielded through a rabi cycle. further, several common issues of the rab gates are solved by modifying the parameter relation. the gate fidelity and the gate robustness against the control error are enhanced with a shaped pulse. the requirement of control precision of the rydberg - rydberg interaction strength is relaxed. in addition, the atomic excitation is restrained and therefore the gate robustness against the atomic decay is enhanced. | arxiv:2003.02691 |
signal formation mechanism of piezoresponse force microscopy of piezoelectric surface layers and thin films on stiff and elastically matched substrates is analyzed and thickness dependence of effective piezoelectric response, object transfer function components and rayleigh two - point resolution are derived. obtained exact series and simple pade approximations can be applied for the effective piezoresponse analytical calculations in the case of films capped on different substrates. the effective piezoresponse is thickness dependent for piezoelectric films on substrates with low dielectric permittivity ( extrinsic size effect ), whereas the thickness dependence is essentially suppressed for giant permittivity or metallic substrates. thus implications of analysis for ferroelectric data storage and device applications are discussed. | arxiv:0705.3449 |
in this paper we extend the falicov - kimball model ( fkm ) to the case where the " quasi - particles " entering the fkm are not " ordinary " fermions. as an example we first discuss how the fkm can be generalized to the case with spin - dependent hopping. afterwards we discuss several cases where the " quasi - particles " entering the fkm are majorana fermions ( extended majorana - falicov - kimball model ( mfkm ). two examples of extended mfkm are discussed in detail : ( i ) a $ p $ - wave bcs superconductor on a bipartite lattice and ( ii ) a bcs - anderson model. we also discuss the most general forms of extended mfkm, including a brief discussion on the case where the majorana fermions represent spins, but not real fermion particles. | arxiv:1903.05013 |
the maximum absolute correlation between regressors, which is called mutual coherence, plays an essential role in sparse estimation. a regressor matrix whose columns are highly correlated may result from optimal input design, since there is no constraint on the mutual coherence, making it difficult to handle sparse estimation. this paper aims to tackle this issue for fixed denominator models, which include laguerre, kautz, and generalized orthonormal basis function expansion models, for example. the paper proposes an optimal input design method where the achieved fisher information matrix is fitted to the desired fisher matrix, together with a coordinate transformation designed to make the regressors in the transformed coordinates have low mutual coherence. the method can be used together with any sparse estimation method and any desired fisher matrix. a numerical study shows its potential for alleviating the problem of model order selection when used in conjunction with, for example, classical methods such as the akaike information criterion. | arxiv:2402.06048 |
we perform a systematic search for sub - parsec binary supermassive black holes ( bhs ) in normal broad line quasars at z < 0. 8, using multi - epoch sdss spectroscopy of the broad hbeta line. our working model is that : only one of the two bhs in the binary is active, and dynamically dominates its own broad line region ( blr ) ; the inactive companion bh is orbiting at a distance of a few r _ blr, where r _ blr ~ 0. 01 - 0. 1 pc is the blr size. we search for the expected line - of - sight acceleration of the broad line velocity from binary orbital motion by cross - correlating sdss spectra from two epochs separated by up to several years in the quasar restframe. out of ~ 700 pairs of spectra for which we have good measurements of the velocity shift between two epochs ( 1 - sigma error ~ 40 km / s ), we detect 28 systems with significant velocity shifts in broad hbeta, among which seven are the best candidates for the hypothesized binaries. we use the distribution of the observed accelerations ( mostly non - detections ) to place constraints on the abundance of such binary systems among the general quasar population. excess variance in the velocity shift is inferred for observations separated by longer than 0. 4 yr ( quasar restframe ). attributing all the excess to binary motion would imply that most of the quasars in this sample must be in binaries ; that the inactive bh must be on average more massive than the active one ; and that the binary separation is at most a few times the size of the blr. however, if this excess variance is partly or largely due to long - term broad line variability, the requirement of a large population of close binaries is much weakened or even disfavored for massive companions. [ abridged ] | arxiv:1306.4330 |
cloud service owners need to continuously monitor their services to ensure high availability and reliability. gaps in monitoring can lead to delay in incident detection and significant negative customer impact. current process of monitor creation is ad - hoc and reactive in nature. developers create monitors using their tribal knowledge and, primarily, a trial and error based process. as a result, monitors often have incomplete coverage which leads to production issues, or, redundancy which results in noise and wasted effort. in this work, we address this issue by proposing an intelligent monitoring framework that recommends monitors for cloud services based on their service properties. we start by mining the attributes of 30, 000 + monitors from 791 production services at microsoft and derive a structured ontology for monitors. we focus on two crucial dimensions : what to monitor ( resources ) and which metrics to monitor. we conduct an extensive empirical study and derive key insights on the major classes of monitors employed by cloud services at microsoft, their associated dimensions, and the interrelationship between service properties and this ontology. using these insights, we propose a deep learning based framework that recommends monitors based on the service properties. finally, we conduct a user study with engineers from microsoft which demonstrates the usefulness of the proposed framework. the proposed framework along with the ontology driven projections, succeeded in creating production quality recommendations for majority of resource classes. this was also validated by the users from the study who rated the framework ' s usefulness as 4. 27 out of 5. | arxiv:2403.07927 |
we carry out the determination of the amplitude of relic gravitational waves power spectrum. indirect best - fit technique was applied to compare observational data and theory predictions. as observations we have used data on large - scale structure ( lss ) of the universe and anisotropy of cosmic microwave background ( cmb ) temperature. the conventional inflationary model with 11 parameters has been investigated, all of them evaluated jointly. this approach gave us a possibility to find parameters of power spectrum of gravitational waves along with statistical errors. the main result consists in following : wmap data on power spectrum of cmb temperature fluctuations along with lss data prefer model with small amplitude of tensor mode power spectrum, close to zero. the upper limit for its amplitude at quadupole harmonics t / s = 0. 6 at 95 % c. l. | arxiv:astro-ph/0412060 |
the phase structure of a non - isotropic non - abelian su ( 3 ) lattice gauge model at finite temperature is investigated to the third order in the variational - cumulant expansion ( vce ) approach. the layer phase exists in this model in the cases of dimensions d = 4, d = 5 ( d = d - 1 ). | arxiv:hep-th/0101146 |
we prove that the limit profile of star transpositions at time $ t = n \ log n + cn $ is equal to $ d _ { \ text { t. v. } } ( \ text { poiss } ( 1 + e ^ { - c } ), \ text { poiss } ( 1 ) ) $. we prove this by developing a technique for comparing the limit profile behavior of two reversible markov chains on the same space, that share the same stationary distribution and eigenbasis. we then compare the limit profile of star transpositions to the limit profile of random transpositions, as studied in \ cite { teyssier }, and prove that they have the same limit profile at the respective cutoff times. | arxiv:2111.03622 |
due to the intrinsic complexity of the quantum many - body problem, quantum monte carlo algorithms and their corresponding monte carlo configurations can be defined in various ways. configurations corresponding to few feynman diagrams often lead to severe sign problems. on the other hand, computing the configuration weight becomes numerically expensive in the opposite limit in which many diagrams are grouped together. here we show that for continuous - time quantum monte carlo in the hybridization expansion the efficiency can be substantially improved by dividing the local impurity trace into fragments, which are then sampled individually. for this technique, which also turns out to preserve the fermionic sign, a modified update strategy is introduced in order to ensure ergodicity. our ( super ) state sampling is particularly beneficial to calculations with many $ d $ - orbitals and general local interactions, such as full coulomb interaction. for illustration, we reconsider the simple albeit well - known case of a degenerate three - orbital model at low temperatures. this allows us to quantify the coherence properties of the " spin - freezing " crossover, even close to the mott transition. | arxiv:1807.00361 |
we define the hypergeometric exponential sum associated to a finite family of representations of a reductive group over a finite field. we introduce the hypergeometric $ \ ell $ - adic sheaf to describe the behavior of the hypergeometric exponential sum. it is a perverse sheaf, and it is the counterpart in characteristic $ p $ of the $ a $ - hypergeometric $ \ mathcal d $ - module introduced by kapranov. using the theory of the fourier transform for vector bundles over a general base developed by wang, we are able to study the hypergeometric $ \ ell $ - adic sheaf via the hypergeometric $ \ mathcal d $ - module. we apply our results to the estimation of the hypergeometric exponential sum. | arxiv:2411.11215 |
this review presents a comprehensive study of the spatial dispersion of propagating magnons electrically emitted in extended yttrium - iron garnet ( yig ) films by the spin transfer effects across a yig $ \ vert $ pt interface. our goal is to provide a generic framework to describe the magnon transconductance inside magnetic films. we experimentally elucidate the relevant spectral contributions by studying the lateral decay of the magnon signal. while most of the injected magnons do not reach the collector, the propagating magnons can be split into two - fluids : \ textit { i ) } a large fraction of high - energy magnons carrying energy of about $ k _ b t _ 0 $, where $ t _ 0 $ is the lattice temperature, with a characteristic decay length in the sub - micrometer range, and \ textit { ii ) } a small fraction of low - energy magnons, which are particles carrying energy of about $ \ hbar \ omega _ k $, where $ \ omega _ k / ( 2 \ pi ) $ is the kittel frequency, with a characteristic decay length in the micrometer range. taking advantage of their different physical properties, the low - energy magnons can become the dominant fluid \ textit { i ) } at large spin transfer rates for the bias causing the emission of magnons, \ textit { ii ) } at large distance from the emitter, \ textit { iii ) } at small film thickness, or \ textit { iv ) } for reduced band mismatch between the yig below the emitter and the bulk due to variation of the magnon concentration. this broader picture complements part i \ cite { kohno _ sd }, which focuses solely on the nonlinear transport properties of low - energy magnons. | arxiv:2210.08283 |
many open problems in biology, as in the physical sciences, display nonlinear and ' chaotic ' dynamics, which, to the extent possible, cannot be reasonably understood. moreover, mathematical models which aim to predict / estimate unknown aspects of a biological system cannot provide more information about the set of biologically meaningful ( e. g., ' hidden ' ) states of the system than could be understood by the designer of the model ab initio. here, the case is made for the utilization of such models to shift from a ' predictive ' to a ' questioning ' nature, and a simple natural - logarithm variation of the logistic polynomial map is presented that can invoke questions about protein trafficking in eukaryotic cells. | arxiv:1206.5557 |
a search is conducted for new physics in a final state containing a photon and missing transverse momentum in proton - proton collisions at sqrt ( s ) = 13 tev. the data collected by the cms experiment at the cern lhc correspond to an integrated luminosity of 12. 9 inverse femtobarns. no deviations are observed relative to the predictions of the standard model. the results are interpreted as exclusion limits on the dark matter production cross sections and parameters in models containing extra spatial dimensions. improved limits are set with respect to previous searches using the monophoton final state. in particular, the limits on the extra dimension model parameters are the most stringent to date in this channel. | arxiv:1706.03794 |
using maximally localized wannier functions obtained from dft calculations, we derive an effective hubbard hamiltonian for a bilayer of sr $ _ 3 $ cr $ _ 2 $ o $ _ 7 $, the $ n = 2 $ member of the ruddlesden - popper sr $ _ { n + 1 } $ cr $ _ n $ o $ _ { 3n + 1 } $ system. the model consists of effective $ t _ { 2g } $ orbitals of cr in two square lattices, one above the other. the model is further reduced at low energies and two electrons per site, to an effective kugel - khomskii hamiltonian that describes interacting spins 1 and pseudospins 1 / 2 at each site describing spin and orbitals degrees of freedom respectively. we solve this hamiltonian at zero temperature using pseudospin bond operators and spin waves. our results confirm a previous experimental and theoretical study that proposes spin ordering antiferromagnetic in the planes and ferromagnetic between planes, while pseudospins form vertical singlets, although the interplane separation is larger than the nearest - neighbor distance in the plane. we explain the physics behind this rather unexpected behavior. | arxiv:1811.12749 |
in this paper we present morphy, an integrated tool for german morphology, part - of - speech tagging and context - sensitive lemmatization. its large lexicon of more than 320, 000 word forms plus its ability to process german compound nouns guarantee a wide morphological coverage. syntactic ambiguities can be resolved with a standard statistical part - of - speech tagger. by using the output of the tagger, the lemmatizer can determine the correct root even for ambiguous word forms. the complete package is freely available and can be downloaded from the world wide web. | arxiv:cs/9809050 |
multimodal clothing image editing refers to the precise adjustment and modification of clothing images using data such as textual descriptions and visual images as control conditions, which effectively improves the work efficiency of designers and reduces the threshold for user design. in this paper, we propose a new image editing method controledit, which transfers clothing image editing to multimodal - guided local inpainting of clothing images. we address the difficulty of collecting real image datasets by leveraging the self - supervised learning approach. based on this learning approach, we extend the channels of the feature extraction network to ensure consistent clothing image style before and after editing, and we design an inverse latent loss function to achieve soft control over the content of non - edited areas. in addition, we adopt blended latent diffusion as the sampling method to make the editing boundaries transition naturally and enforce consistency of non - edited area content. extensive experiments demonstrate that controledit surpasses baseline algorithms in both qualitative and quantitative evaluations. | arxiv:2409.14720 |
the bare diffusion coefficient is given as the time integral of the peculiar velocity autocorrelation function or pvacf and this result is different from the well known green - kubo formula. the bare diffusion coefficient characterizes the diffusion process on a length scale lambda. the pvacf is given here for the first time in terms of the positions and velocities of the n particles of the system so the pvacf is in a form suitable for evaluation by molecular dynamics simulations. the computer simulations show that for the two dimensional hard disk system, the pvacf decays increasingly rapidly in time as lambda is reduced and this is probably a general characteristic. | arxiv:cond-mat/0402422 |
we consider topological defect networks with junctions in $ a _ { n - 1 } $ toda cft and the connection to supersymmetric loop operators in $ \ mathcal { n } = 2 $ theories of class s on a four - sphere. correlation functions in the presence of topological defect networks are computed by exploiting the monodromy of conformal blocks, generalising the notion of a verlinde operator. concentrating on a class of topological defects in $ a _ 2 $ toda theory, we find that the verlinde operators generate an algebra whose structure is determined by a set of generalised skein relations. these relations encode the representation theory of a quantum group. in the second half of the paper, we explore the dictionary between topological defect networks and supersymmetric loop operators in the $ \ mathcal { n } = 2 ^ * $ star theory by comparing to exact localisation computations. in this context, the the generalised skein relations are related to the operator product expansion of loop operators. | arxiv:1312.5001 |
transport and magnetic properties of lsmo manganite thin films and bicrystal junctions were investigated. manganite films were epitaxially grown on sto, lao, ngo and lsat substrates and their magnetic anisotropy were determined by two techniques of magnetic resonance spectroscopy. compare with cubic substrates a small ( about 0. 3 persentage ), the anisotropy of the orthorhombic ngo substrate leads to a uniaxial anisotropy of the magnetic properties of the films in the plane of the substrate. samples with different tilt of crystallographic basal planes of manganite as well as bicrystal junctions with rotation of the crystallographic axes ( rb - junction ) and with tilting of basal planes ( tb - junction ) were investigated. it was found that on vicinal ngo substrates the value of magnetic anisotropy could be varied by changing the substrate inclination angle from 0 to 25 degrees. measurement of magnetic anisotropy of manganite bicrystal junction demonstrated the presence of two ferromagnetically ordered spin subsystems for both types of bicrystal boundaries rb and tb. the magnitude of the magnetoresistance for tb - junctions increased with decreasing temperature and with the misorientation angle even misorientation of easy axes in the parts of junction does not change. analysis of the voltage dependencies of bicrystal junction conductivity show that the low value of the magnetoresistance for the lsmo bicrystal junctions can be caused by two scattering mechanisms with the spin - flip of spin - polarized carriers due to the strong electron - electron interactions in a disordered layer at the bicrystal boundary at low temperatures and the spin - flip by anti ferromagnetic magnons at high temperatures. | arxiv:1210.2261 |
the problem of the cosmic coincidence is a longstanding puzzle. this conundrum may be solved by introducing a coupling between the two dark sectors. in this letter, we study two cases of the coupled quintessence scenario. $ ( a ) $ assume that the mass of dark matter particles depends exponentially on the scalar field associated to dark energy and meanwhile the scalar field evolves in an exponential potential ; $ ( b ) $ assume that the mass of dark matter particles depends on a power law function of the scalar field and meanwhile the scalar field evolves in a power law potential. since the dynamics of this system is dominated by an attractor solution, the mass of dark matter particles is forced to change with time as to ensure that the ratio between the energy densities of dark matter and dark energy becomes a constant at late times, and one thus solve the cosmic coincidence problem naturally. we perform a statefinder diagnostic to both cases of this coupled quintessence scenario. it is shown that the evolving trajectory of this scenario in the $ s - r $ diagram is quite different from those of other dark energy models. | arxiv:astro-ph/0503075 |
as bands like korn and system of a down during their independent years, despite having similar influences. in interviews from the late 2010s and 2020s, boyd has said that he dislikes the nu metal label and doesn ' t consider the band ' s early work to be part of the movement. in a 2022 metal hammer interview, he remarked, " we weren ’ t trying to fit into a particular niche at a particular time. we were just kids being influenced by a small handful of bands that we grew up with. " revolver describe brandon boyd as vocally " drawing on the eccentric funk - rap " of faith no more, primus and red hot chili peppers. they consider him to have a " goofy yet also badass presence " on s. c. i. e. n. c. e. boyd has cited faith no more ' s vocalist mike patton as being an influence from since he was an early teenager, as well as patton ' s side project mr. bungle, who were similarly known for mixing a wide array of genres. through mr. bungle, boyd also went on to become a fan of avant - garde musician john zorn, who produced their 1991 debut album. in a 2003 interview with the philippine daily inquirer, boyd said that around this period, both he and einziger gravitated towards more experimental artists that " you ' ll never hear on the radio ". alex katunich uses a slap bass playing style on the album, and has said he was influenced by funk music since he was a young child, and got an album of disney songs done in disco style. when he became a teenager, he said faith no more ' s 1989 album the real thing began influencing him, in addition to becoming influenced by mr. bungle and other funk metal bands, such as infectious grooves, primus and red hot chili peppers. in a 1998 interview, boyd was asked about whether incubus was influenced by faith no more, who had broken up in april of that year, and he commented, " there ' s a definite influence from faith no more. all of us have been listening to that band since when we were really young. we were like 14 or something when that album [ the real thing ] came out. they were an awesome band, they did some really groundbreaking things in their time, and it ' s kind of a bummer to hear that they broke up. " boyd also noted in october 1997 that they were frequently compared to both faith no more and the red hot chili | https://en.wikipedia.org/wiki/S.C.I.E.N.C.E. |
galaxy morphology classification plays a crucial role in understanding the structure and evolution of the universe. with galaxy observation data growing exponentially, machine learning has become a core technology for this classification task. however, traditional machine learning methods predominantly rely on supervised learning frameworks, and their dependence on large of labeled samples limits practical applications. to address this challenge, we propose an innovative hybrid semi - supervised model, gc - swgan, designed to tackle galaxy morphology classification under conditions of limited labeled data. this model integrates semi - supervised generative adversarial networks ( sgan ) with wasserstein gan with gradient penalty ( wgan - gp ), establishing a multi - task learning framework. within this framework, the discriminator and classifier are designed independently while sharing part of the architecture. by collaborating with the generator, the model significantly enhances both classification performance and sample generation capabilities, while also improving convergence and stability during training. experimental results demonstrate that, on the galaxy10 decals dataset, gc - swgan achieves comparable or even superior classification accuracy ( exceeding 75 % ) using only one - fifth of the labeled samples typically required by conventional fully supervised methods. under identical labeled conditions, the model displays excellent generalization performance, attaining approximately 84 % classification accuracy. notably, in extreme scenarios where only 10 \ % of the data is labeled, gc - swgan still achieves high classification accuracy ( over 68 % ), fully demonstrating its stability and effectiveness in low - labeled data environments. furthermore, galaxy images generated by gc - swgan are visually similar to real samples. | arxiv:2504.00500 |
the magnetoresistance ( mr ) associated with domain boundaries has been investigated in microfabricated bcc fe ( 0. 65 to 20 $ \ mu $ m linewidth ) wires with controlled stripe domains. domain configurations have been characterized using magnetic force microscopy. mr measurements as a function of field angle, temperature and domain configuration are used to estimate mr contributions due to resistivity anisotropy and domain walls. evidence is presented that domain boundaries enhance the conductivity in such microstructures over a broad range of temperatures ( 1. 5 k to 80 k ). | arxiv:cond-mat/9803101 |
in purely c - axis oriented pbzr $ _ { 0. 2 } $ ti $ _ { 0. 8 } $ o $ _ 3 $ ferroelectric thin films, a lateral piezoresponse force microscopy signal is observed at the position of 180 { \ deg } domain walls, where the out - of - plane oriented polarization is reversed. using electric force microscopy measurements we exclude electrostatic effects as the origin of this signal. moreover, our mechanical simulations of the tip / cantilever system show that the small tilt of the surface at the domain wall below the tip does not satisfactorily explain the observed signal either. we thus attribute this lateral piezoresponse at domain walls to their sideways motion ( shear ) under the applied electric field. from simple elastic considerations and the conservation of volume of the unit cell, we would expect a similar lateral signal more generally in other ferroelectric materials, and for all types of domain walls in which the out - of - plane component of the polarization is reversed through the domain wall. we show that in bifeo $ _ 3 $ thin films, with 180, 109 and 71 { \ deg } domain walls, this is indeed the case. | arxiv:1006.1237 |
recent work on adversarial attack and defense suggests that pgd is a universal $ l _ \ infty $ first - order attack, and pgd adversarial training can significantly improve network robustness against a wide range of first - order $ l _ \ infty $ - bounded attacks, represented as the state - of - the - art defense method. however, an obvious weakness of pgd adversarial training is its highly - computational cost in generating adversarial samples, making it computationally infeasible for large and high - resolution real datasets such as the imagenet dataset. in addition, recent work also has suggested a simple " close - form " solution to a robust model on mnist. therefore, a natural question raised is that is pgd adversarial training really necessary for robust defense? in this paper, we give a negative answer by proposing a training paradigm that is comparable to pgd adversarial training on several standard datasets, while only using noisy - natural samples. specifically, we reformulate the min - max objective in pgd adversarial training by a problem to minimize the original network loss plus $ l _ 1 $ norms of its gradients w. r. t. the inputs. for the $ l _ 1 $ - norm loss, we propose a computationally - feasible solution by embedding a differentiable soft - quantization layer after the network input layer. we show formally that the soft - quantization layer trained with noisy - natural samples is an alternative approach to minimizing the $ l _ 1 $ - gradient norms as in pgd adversarial training. extensive empirical evaluations on standard datasets show that our proposed models are comparable to pgd - adversarially - trained models under pgd and bpda attacks. remarkably, our method achieves a 24x speed - up on mnist while maintaining a comparable defensive ability, and for the first time fine - tunes a robust imagenet model within only two days. code is provided on \ url { https : / / github. com / tianzheng4 / noisy - training - soft - quantization } | arxiv:1810.05665 |
ages, metallicities, space velocities, and galactic orbits of stars in the solar neighbourhood are fundamental observational constraints on models of galactic disk evolution. we aim to consolidate the calibrations of uvby photometry into te, [ fe / h ], distance, and age for f and g stars and rediscuss the results of the geneva - copenhagen survey ( nordstrom et al. 2004 ; gcs ) in terms of the evolution of the disk. we substantially improve the te and [ fe / h ] calibrations for early f stars, where spectroscopic temperatures have large systematic errors. our recomputed ages are in excellent agreement with the independent determinations by takeda et al. ( 2007 ), indicating that isochrone ages can now be reliably determined. the revised g - dwarf metallicity distribution remains incompatible with closed - box models, and the age - metallicity relation for the thin disk remains almost flat, with large and real scatter at all ages ( sigma intrinsic = 0. 20 dex ). dynamical heating of the thin disk continues throughout its life ; specific in - plane dynamical effects dominate the evolution of the u and v velocities, while the w velocities remain random at all ages. when assigning thick and thin - disk membership for stars from kinematic criteria, parameters for the oldest stars should be used to characterise the thin disk. | arxiv:0707.1891 |
due to the appearance of uncontrollable events in discrete event systems, one may wish to replace the behavior leading to the uncontrollability of pre - specified language by some quite similar one. to capture this similarity, we introduce metric to traditional supervisory control theory and generalize the concept of original controllability to $ \ ld $ - controllability, where $ \ ld $ indicates the similarity degree of two languages. a necessary and sufficient condition for a language to be $ \ ld $ - controllable is provided. we then examine some properties of $ \ ld $ - controllable languages and present an approach to optimizing a realization. | arxiv:cs/0410031 |
this paper proposes quantum image reconstruction. input - triggered selection of an image among many stored ones, and its reconstruction if the input is occluded or noisy, has been simulated by a computer program implementable in a real quantum - physical system. it is based on the hopfield associative net ; the quantum - wave implementation bases on holography. the main limitations of the classical hopfield net are much reduced with the new, original - - quantum - optical - - implementation. image resolution can be almost arbitrarily increased. | arxiv:quant-ph/0401016 |
the potential of multimodal generative artificial intelligence ( mai ) to replicate human grounded language understanding, including the pragmatic, context - rich aspects of communication, remains to be clarified. humans are known to use salient multimodal features, such as visual cues, to facilitate the processing of upcoming words. correspondingly, multimodal computational models can integrate visual and linguistic data using a visual attention mechanism to assign next - word probabilities. to test whether these processes align, we tasked both human participants ( n = 200 ) as well as several state - of - the - art computational models with evaluating the predictability of forthcoming words after viewing short audio - only or audio - visual clips with speech. during the task, the model ' s attention weights were recorded and human attention was indexed via eye tracking. results show that predictability estimates from humans aligned more closely with scores generated from multimodal models vs. their unimodal counterparts. furthermore, including an attention mechanism doubled alignment with human judgments when visual and linguistic context facilitated predictions. in these cases, the model ' s attention patches and human eye tracking significantly overlapped. our results indicate that improved modeling of naturalistic language processing in mai does not merely depend on training diet but can be driven by multimodality in combination with attention - based architectures. humans and computational models alike can leverage the predictive constraints of multimodal information by attending to relevant features in the input. | arxiv:2308.06035 |
we describe a suite of validation metrics that assess the credibility of a given automatic spike sorting algorithm applied to a given electrophysiological recording, when ground - truth is unavailable. by rerunning the spike sorter two or more times, the metrics measure stability under various perturbations consistent with variations in the data itself, making no assumptions about the noise model, nor about the internal workings of the sorting algorithm. such stability is a prerequisite for reproducibility of results. we illustrate the metrics on standard sorting algorithms for both in vivo and ex vivo recordings. we believe that such metrics could reduce the significant human labor currently spent on validation, and should form an essential part of large - scale automated spike sorting and systematic benchmarking of algorithms. | arxiv:1508.06936 |
this paper is the fourth in a series devoted to the development of a rigorous renormalisation group method for lattice field theories involving boson fields, fermion fields, or both. the third paper in the series presents a perturbative analysis of a supersymmetric field theory which represents the continuous - time weakly self - avoiding walk on $ \ mathbb { z } ^ d $. we now present an analysis of the relevant interaction functional of the supersymmetric field theory, which permits a nonperturbative analysis to be carried out in the critical dimension $ d = 4 $. the results in this paper include : proof of stability of the interaction, estimates which enable control of gaussian expectations involving both boson and fermion fields, estimates which bound the errors in the perturbative analysis, and a crucial contraction estimate to handle irrelevant directions in the flow of the renormalisation group. these results are essential for the analysis of the general renormalisation group step in the fifth paper in the series. | arxiv:1403.7255 |
we present the microscopic kinetic theory of a homogeneous dilute bose condensed gas in the generalized random phase approximation ( grpa ), which satisfies the following requirements : 1 ) the mass, momentum and energy conservation laws ; 2 ) the h - theorem ; 3 ) the superfluidity property and 4 ) the recovery of the bogoliubov theory at zero temperature \ cite { condenson }. in this approach, the condensate influences the binary collisional process between the two normal atoms, in the sense that their interaction force results from the mediation of a bogoliubov collective excitation traveling throughout the condensate. furthermore, as long as the bose gas is stable, no collision happens between condensed and normal atoms. in this paper, we show how the kinetic theory in the grpa allows to calculate the dynamic structure factor at finite temperature and when the normal and superfluid are in a relative motion. the obtained spectrum for this factor provides a prediction which, compared to the experimental results, allows to validate the grpa. pacs numbers : 03. 75. hh, 03. 75. kk, 05. 30. - d | arxiv:cond-mat/0406033 |
by placing the biased tip of an atomic force microscope at a specific position above a semiconductor surface we can locally shape the potential landscape. inducing a local repulsive potential in a two dimensional electron gas near a quantum point contact one obtains a potential minimum which exhibits a remarkable behavior in transport experiments at high magnetic fields and low temperatures. in such an experiment we observe distinct and reproducible oscillations in the measured conductance as a function of magnetic field, voltages and tip position. they follow a systematic behavior consistent with a resonant tunneling mechanism. from the periodicity in magnetic field we can find the characteristic width of this minimum to be of the order of 100 nm. surprisingly, this value remains almost the same for different values of the bulk filling factors, although the tip position has to be adjusted by distances of the order of one micron. | arxiv:1401.8207 |
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