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purpose : this is an attempt to better bridge the gap between the mathematical and the engineering / physical aspects of the topic. we trace the different sources of non - convexification in the context of topology optimization problems starting from domain discretization, passing through penalization for discreteness and effects of filtering methods, and end with a note on continuation methods. design / methodology / approach : starting from the global optimum of the compliance minimization problem, we employ analytical tools to investigate how intermediate density penalization affects the convexity of the problem, the potential penalization - like effects of various filtering techniques, how continuation methods can be used to approach the global optimum, and how the initial guess has some weight in determining the final optimum. findings : the non - convexification effects of the penalization of intermediate density elements simply overshadows any other type of non - convexification introduced into the problem, mainly due to its severity and locality. continuation methods are strongly recommended to overcome the problem of local minima, albeit its step and convergence criteria are left to the user depending on the type of application. originality / value : in this article, we present a comprehensive treatment of the sources of non - convexity in density - based topology optimization problems, with a focus on linear elastic compliance minimization. we put special emphasis on the potential penalization - like effects of various filtering techniques through a detailed mathematical treatment.
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arxiv:2107.04468
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we propose an unsupervised method for sentence summarization using only language modeling. the approach employs two language models, one that is generic ( i. e. pretrained ), and the other that is specific to the target domain. we show that by using a product - of - experts criteria these are enough for maintaining continuous contextual matching while maintaining output fluency. experiments on both abstractive and extractive sentence summarization data sets show promising results of our method without being exposed to any paired data.
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arxiv:1907.13337
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simulating the distribution of cosmological neutral hydrogen ( hi ) during the epoch of reionization requires a high dynamic range and is hence computationally expensive. the size of the simulation is dictated by the largest scales one aims to probe, while the resolution is determined by the smallest dark matter haloes capable of hosting the first stars. we present a hybrid approach where the density and tidal fields of a large - volume, low - resolution simulation are combined with small haloes from a small - volume, high - resolution box. by merging these two boxes of relatively lower dynamic range, we achieve an effective high - dynamic range simulation using only 13 % of the computational resources required for a full high - dynamic range simulation. our method accurately reproduces the one - and two - point statistics of the halo field, its cross - correlation with the dark matter density field, and the two - point statistics of the hi field computed using a semi - numerical code, all within 10 % accuracy at large scales and across different redshifts. our technique, combined with semi - numerical models of reionization, provides a resource - efficient tool for modeling the hi distribution at high redshifts.
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arxiv:2407.10585
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we study the ruderman - kittel - kasuya - yosida ( rkky ) interaction between two contact magnetic impurities placed on bilayer graphene ( blg ). we compute the interaction mediated by the carriers of the pristine and biased blg as well as the conduction electrons of the doped system. the results are obtained from the linear - response expression for the susceptibility written in terms of the integral over lattice green ' s functions. for the unbiased system, we obtain some analytical expressions in terms of the meijer g - functions, which consist of the product of two oscillatory terms, one coming from the interference between the two dirac points and the second coming from the fermi momentum. in particular, for the undoped blg, the system exhibits the rkky interaction commensurate with its bipartite nature as expected from the particle - hole symmetry of the system. furthermore, we explore a beating pattern of oscillations of the rkky interaction in a highly doped blg system within the four - band continuum model. besides, we discuss the discrepancy between the short - range rkky interaction calculated from the two - band model and that obtained from the four - band continuum model. the final results for the applied gate voltage are obtained numerically and are fitted with the functional forms based on the results for the unbiased case. in this case, we show that the long - range behavior is scaled with a momentum that depends on fermi energy and gate voltage, allowing the possibility of tuning of the rkky interaction by gate voltage.
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arxiv:1302.3649
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over the last five years, research on relation extraction ( re ) witnessed extensive progress with many new dataset releases. at the same time, setup clarity has decreased, contributing to increased difficulty of reliable empirical evaluation ( taill \ ' e et al., 2020 ). in this paper, we provide a comprehensive survey of re datasets, and revisit the task definition and its adoption by the community. we find that cross - dataset and cross - domain setups are particularly lacking. we present an empirical study on scientific relation classification across two datasets. despite large data overlap, our analysis reveals substantial discrepancies in annotation. annotation discrepancies strongly impact relation classification performance, explaining large drops in cross - dataset evaluations. variation within further sub - domains exists but impacts relation classification only to limited degrees. overall, our study calls for more rigour in reporting setups in re and evaluation across multiple test sets.
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arxiv:2204.13516
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if supersymmetry ( susy ) is realized at the electroweak scale, its underlying structure and breaking mechanism may be explored with great precision by a future linear $ e ^ + e ^ - $ collider ( lc ) with a clean environment, tunable collision energy, high luminosity polarized beams, and additional $ e ^ - e ^ - $, $ e \ gamma $ and $ \ gamma \ gamma $ modes. in this report we summarize four papers submitted to the ichep04 conference about the precise measurements of the top squark parameters and $ \ tan \ beta $, the impacts of the cp phases on the search for top / bottom squarks, the majorana nature and cp violation in the neutralino system, the implications of the susy dark matter scenario for the lc experiments, and the characteristics of the neutralino sector of the next - - to - - minimal supersymmetric standard model at the lc
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arxiv:hep-ph/0410359
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tunneling in quantum field theory is well understood in the case of a single scalar field. however, in theories with spontaneous symmetry breaking, one has to take into account the additional zero modes which appear due to the goldstone phenomenon. we calculate the false vacuum decay rate in this case. the result may differ significantly from the tunneling rates in the absence of symmetry breaking.
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arxiv:hep-ph/9506386
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to generalize the notion of recurrent manifold, there are various recurrent like conditions in the literature. in this paper we present a recurrent like structure, namely, \ textit { super generalized recurrent manifold }, which generalizes both the hyper generalized recurrent manifold and weakly generalized recurrent manifold. the main object of the present paper is to study the geometric properties of super generalized recurrent manifold. finally to ensure the existence of such structure we present a proper example by a suitable metric.
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arxiv:1504.02535
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i discuss recent work our group has undertaken on effective - field - theory analyses of experimental data pertaining to one - and two - neutron halo nuclei.
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arxiv:1311.5103
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very recently proximal policy optimization ( ppo ) algorithms have been proposed as first - order optimization methods for effective reinforcement learning. while ppo is inspired by the same learning theory that justifies trust region policy optimization ( trpo ), ppo substantially simplifies algorithm design and improves data efficiency by performing multiple epochs of \ emph { clipped policy optimization } from sampled data. although clipping in ppo stands for an important new mechanism for efficient and reliable policy update, it may fail to adaptively improve learning performance in accordance with the importance of each sampled state. to address this issue, a new surrogate learning objective featuring an adaptive clipping mechanism is proposed in this paper, enabling us to develop a new algorithm, known as ppo - $ \ lambda $. ppo - $ \ lambda $ optimizes policies repeatedly based on a theoretical target for adaptive policy improvement. meanwhile, destructively large policy update can be effectively prevented through both clipping and adaptive control of a hyperparameter $ \ lambda $ in ppo - $ \ lambda $, ensuring high learning reliability. ppo - $ \ lambda $ enjoys the same simple and efficient design as ppo. empirically on several atari game playing tasks and benchmark control tasks, ppo - $ \ lambda $ also achieved clearly better performance than ppo.
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arxiv:1804.06461
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polarons, introduced by davydov to explain energy transport in $ \ alpha $ - helices, correspond to electrons localised on a few lattice sites because of their interaction with phonons. while the static polaron field configurations have been extensively studied, their displacement is more difficult to explain. in this paper we show that, when the next to nearest neighbour interactions are included, for physical values of the parameters, polarons can spontaneously move, at t = 0, on bent chains that exhibit a positive gradient in their curvature. at room temperature polarons perform a random walk but a curvature gradient can induce a non - zero average speed similar to the one observed at zero temperature. we also show that at zero temperature a polaron bounces on sharply kinked junctions. we interpret these results in light of the energy transport by transmembrane proteins.
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arxiv:1108.3694
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motivated by the recent realization of graphene sensors to detect individual gas molecules, we investigate the adsorption of h2o, nh3, co, no2, and no on a graphene substrate using first - principles calculations. the optimal adsorption position and orientation of these molecules on the graphene surface is determined and the adsorption energies are calculated. molecular doping, i. e. charge transfer between the molecules and the graphene surface, is discussed in light of the density of states and the molecular orbitals of the adsorbates. the efficiency of doping of the different molecules is determined and the influence of their magnetic moment is discussed.
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arxiv:0710.1757
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domain adaptation ( da ) aims to transfer discriminative features learned from source domain to target domain. most of da methods focus on enhancing feature transferability through domain - invariance learning. however, source - learned discriminability itself might be tailored to be biased and unsafely transferable by spurious correlations, \ emph { i. e. }, part of source - specific features are correlated with category labels. we find that standard domain - invariance learning suffers from such correlations and incorrectly transfers the source - specifics. to address this issue, we intervene in the learning of feature discriminability using unlabeled target data to guide it to get rid of the domain - specific part and be safely transferable. concretely, we generate counterfactual features that distinguish the domain - specifics from domain - sharable part through a novel feature intervention strategy. to prevent the residence of domain - specifics, the feature discriminability is trained to be invariant to the mutations in the domain - specifics of counterfactual features. experimenting on typical \ emph { one - to - one } unsupervised domain adaptation and challenging domain - agnostic adaptation tasks, the consistent performance improvements of our method over state - of - the - art approaches validate that the learned discriminative features are more safely transferable and generalize well to novel domains.
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arxiv:2011.03737
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we propose an expectation maximization ( em ) - based algorithm for semi - blind channel estimation of reciprocal channels in amplify - and - forward ( af ) two - way relay networks ( twrns ). by incorporating both data samples and pilots into the estimation, the proposed algorithm provides substantially higher accuracy than the conventional training - based approach. furthermore, the proposed algorithm has a linear computational complexity per iteration and converges after a small number of iterations.
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arxiv:1304.6617
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subjective interpretation and content diversity make predicting whether an image is private or public a challenging task. graph neural networks combined with convolutional neural networks ( cnns ), which consist of 14, 000 to 500 millions parameters, generate features for visual entities ( e. g., scene and object types ) and identify the entities that contribute to the decision. in this paper, we show that using a simpler combination of transfer learning and a cnn to relate privacy with scene types optimises only 732 parameters while achieving comparable performance to that of graph - based methods. on the contrary, end - to - end training of graph - based methods can mask the contribution of individual components to the classification performance. furthermore, we show that a high - dimensional feature vector, extracted with cnns for each visual entity, is unnecessary and complexifies the model. the graph component has also negligible impact on performance, which is driven by fine - tuning the cnn to optimise image features for privacy nodes.
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arxiv:2503.12464
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in this work, we consider the rational points on elliptic curves over finite fields f _ { p }. we give results concerning the number of points on the elliptic curve y ^ 2 { \ equiv } x ^ 3 + a ^ 3 ( mod p ) where p is a prime congruent to 1 modulo 6. also some results are given on the sum of abscissae of these points. we give the number of solutions to y ^ 2 { \ equiv } x ^ 3 + a ^ 3 ( modp ), also given in ( [ 1 ], p. 174 ), this time by means of the quadratic residue character, in a different way, by using the cubic residue character. using the weil conjecture, one can generalize the results concerning the number of points in f _ { p } to f _ { p ^ { r } }.
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arxiv:1106.5218
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galaxy morphology is inextricably linked to environment. the morphology - density relation quantifies this relationship. however, optical morphology is only loosely related to the kinematic structure of galaxies, and about two thirds of elliptical ( " spheroidal " ) galaxies are actually misclassified face - on disks, and would appear flattened if view edge on. a more robust classification is the slow / fast rotator classification which describes the kinematic structure. slow and fast rotators form a bimodality in galaxy properties and are thought to follow distinct evolutionary paths, and so a kinematic morphology - density ( kt - $ \ sigma $ ) relation is more meaningful. to date the kt - $ \ sigma $ relation has only been studied for a handful of nearby clusters, or across large numbers of clusters but with incomplete coverage. here, we combine stellar kinematics obtained with the sloan digital sky survey ' s ( sdss ) mapping nearby galaxies at apache point observatory survey with classifications using a novel visual method to obtain the largest complete census of slow and fast rotators in nearby galaxy groups and clusters. to account for incompleteness in the sdss spectroscopic catalogue, we combine the catalogue with the photometric catalogue, which we clean using empirical criteria. we test our visual classification method and find our false negative rate to be only $ \ sim $ 6 % ( 0 % for $ m \ gtrsim 10 ^ { 11. 7 } m _ { \ odot } $ ). in contrast, our false positive rate is about 50 % implying half of all slow rotator candidates will be confirmed as fast rotators if stellar kinematics become available. hence, our misclassification is essentially random with only a weak dependence on stellar mass, and as slow rotators are intrinsically rare, the absolute number of misclassifications will be small compared to the sample size. the result is the largest complete census of massive slow rotator candidates and their environments to date.
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arxiv:1910.05136
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nonperturbative qcd corrections are important to many low - energy electroweak observables, for example the muon magnetic moment. however, hadronic corrections also play a significant role at much higher energies due to their impact on the running of standard model parameters, such as the electromagnetic coupling. currently, these hadronic contributions are accounted for by a combination of experimental measurements, effective field theory techniques and phenomenological modeling but ideally should be calculated from first principles. recent developments indicate that many of the most important hadronic corrections may be feasibly calculated using lattice qcd methods. to illustrate this, we will examine the lattice computation of the leading - order qcd corrections to the muon magnetic moment, paying particular attention to a recently developed method but also reviewing the results from other calculations. we will then continue with several examples that demonstrate the potential impact of the new approach : the leading - order corrections to the electron and tau magnetic moments, the running of the electromagnetic coupling, and a class of the next - to - leading - order corrections for the muon magnetic moment. along the way, we will mention applications to the adler function, which can be used to determine the strong coupling constant, and qcd corrections to muonic - hydrogen.
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arxiv:1206.3113
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we present mesh2nerf, an approach to derive ground - truth radiance fields from textured meshes for 3d generation tasks. many 3d generative approaches represent 3d scenes as radiance fields for training. their ground - truth radiance fields are usually fitted from multi - view renderings from a large - scale synthetic 3d dataset, which often results in artifacts due to occlusions or under - fitting issues. in mesh2nerf, we propose an analytic solution to directly obtain ground - truth radiance fields from 3d meshes, characterizing the density field with an occupancy function featuring a defined surface thickness, and determining view - dependent color through a reflection function considering both the mesh and environment lighting. mesh2nerf extracts accurate radiance fields which provides direct supervision for training generative nerfs and single scene representation. we validate the effectiveness of mesh2nerf across various tasks, achieving a noteworthy 3. 12db improvement in psnr for view synthesis in single scene representation on the abo dataset, a 0. 69 psnr enhancement in the single - view conditional generation of shapenet cars, and notably improved mesh extraction from nerf in the unconditional generation of objaverse mugs.
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arxiv:2403.19319
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we present two new frequency - domain gravitational waveform models for the analysis of signals emitted by binary neutron star coalescences : imrphenomxas _ nrtidalv2 and imrphenomxp _ nrtidalv2. both models are available through the public algorithm library lalsuite and represent the first extensions of imrphenomx models including matter effects. we show here that these two models represent a significant advancement in efficiency and accuracy with respect to their phenomenological predecessors, imrphenomd _ nrtidalv2 and imrphenompv2 _ nrtidalv2. the computational efficiency of the new models is achieved through the application of the same multibanding technique previously applied to binary black hole models. furthermore, imrphenomxp _ nrtidalv2 implements a more accurate description of the precession dynamics, including double - spin effects and, optionally, matter effects in the twisting - up construction. the latter are available through an option to use a numerical integration of the post - newtonian precession equations. we show that the new precession descriptions allow the model to better reproduce the phenomenology observed in numerical - relativity simulations of precessing binary neutron stars. finally, we present some applications of the new models to bayesian parameter estimation studies, including a reanalysis of gw170817 and a study of simulated observations using numerical relativity waveforms for nonprecessing binary neutron stars with highly spinning components. we find that in these cases the new models make a negligible difference in the results. nevertheless, by virtue of the aforementioned improvements, the new models represent valuable tools for the study of future detections of coalescing binary neutron stars.
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arxiv:2311.15978
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end - to - end autonomous driving has advanced significantly, offering benefits such as system simplicity and stronger driving performance in both open - loop and closed - loop settings than conventional pipelines. however, existing frameworks still suffer from low success rates in closed - loop evaluations, highlighting their limitations in real - world deployment. in this paper, we introduce x - driver, a unified multi - modal large language models ( mllms ) framework designed for closed - loop autonomous driving, leveraging chain - of - thought ( cot ) and autoregressive modeling to enhance perception and decision - making. we validate x - driver across multiple autonomous driving tasks using public benchmarks in carla simulation environment, including bench2drive [ 6 ]. our experimental results demonstrate superior closed - loop performance, surpassing the current state - of - the - art ( sota ) while improving the interpretability of driving decisions. these findings underscore the importance of structured reasoning in end - to - end driving and establish x - driver as a strong baseline for future research in closed - loop autonomous driving.
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arxiv:2505.05098
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global registration using 3d point clouds is a crucial technology for mobile platforms to achieve localization or manage loop - closing situations. in recent years, numerous researchers have proposed global registration methods to address a large number of outlier correspondences. unfortunately, the degeneracy problem, which represents the phenomenon in which the number of estimated inliers becomes lower than three, is still potentially inevitable. to tackle the problem, a degeneracy - robust decoupling - based global registration method is proposed, called quatro. in particular, our method employs quasi - so ( 3 ) estimation by leveraging the atlanta world assumption in urban environments to avoid degeneracy in rotation estimation. thus, the minimum degree of freedom ( dof ) of our method is reduced from three to one. as verified in indoor and outdoor 3d lidar datasets, our proposed method yields robust global registration performance compared with other global registration methods, even for distant point cloud pairs. furthermore, the experimental results confirm the applicability of our method as a coarse alignment. our code is available : https : / / github. com / url - kaist / quatro.
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arxiv:2203.06612
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a collision of two - component bose - einstein condensates in the presence of raman coupling is proposed and studied by numerical simulations. raman transitions are found to be able to reduce collision - produced irregular excitations by forming a time - averaged attractive optical potential. raman transitions also support a kind of dark soliton pairs in two - component bose - einstein condensates. soliton pairs and their remnant single solitons are shown to be controllable by adjusting the initial relative phase between the two colliding condensates or the two - photon detuning of raman transitions.
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arxiv:cond-mat/0102004
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in this work, a novel approach for the reliable and efficient numerical integration of the kuramoto model on graphs is studied. for this purpose, the notion of order parameters is revisited for the classical kuramoto model describing all - to - all interactions of a set of oscillators. first numerical experiments confirm that the precomputation of certain sums significantly reduces the computational cost for the evaluation of the right - hand side and hence enables the simulation of high - dimensional systems. in order to design numerical integration methods that are favourable in the context of related dynamical systems on network graphs, the concept of localised order parameters is proposed. in addition, the detection of communities for a complex graph and the transformation of the underlying adjacency matrix to block structure is an essential component for further improvement. it is demonstrated that for a submatrix comprising relatively few coefficients equal to zero, the precomputation of sums is advantageous, whereas straightforward summation is appropriate in the complementary case. concluding theoretical considerations and numerical comparisons show that the strategy of combining effective community detection algorithms with the localisation of order parameters potentially reduces the computation time by several orders of magnitude.
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arxiv:2102.07167
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recent advances in generative models and adversarial training have led to a flourishing image - to - image ( i2i ) translation literature. the current i2i translation approaches require training images from the two domains that are either all paired ( supervised ) or all unpaired ( unsupervised ). in practice, obtaining paired training data in sufficient quantities is often very costly and cumbersome. therefore solutions that employ unpaired data, while less accurate, are largely preferred. in this paper, we aim to bridge the gap between supervised and unsupervised i2i translation, with application to semantic image segmentation. we build upon pix2pix and cyclegan, state - of - the - art seminal i2i translation techniques. we propose a method to select ( very few ) paired training samples and achieve significant improvements in both supervised and unsupervised i2i translation settings over random selection. further, we boost the performance by incorporating both ( selected ) paired and unpaired samples in the training process. our experiments show that an extremely weak supervised i2i translation solution using only one paired training sample can achieve a quantitative performance much better than the unsupervised cyclegan model, and comparable to that of the supervised pix2pix model trained on thousands of pairs.
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arxiv:1909.08542
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event - based cameras are bio - inspired vision sensors whose pixels work independently from each other and respond asynchronously to brightness changes, with microsecond resolution. their advantages make it possible to tackle challenging scenarios in robotics, such as high - speed and high dynamic range scenes. we present a solution to the problem of visual odometry from the data acquired by a stereo event - based camera rig. our system follows a parallel tracking - and - mapping approach, where novel solutions to each subproblem ( 3d reconstruction and camera pose estimation ) are developed with two objectives in mind : being principled and efficient, for real - time operation with commodity hardware. to this end, we seek to maximize the spatio - temporal consistency of stereo event - based data while using a simple and efficient representation. specifically, the mapping module builds a semi - dense 3d map of the scene by fusing depth estimates from multiple local viewpoints ( obtained by spatio - temporal consistency ) in a probabilistic fashion. the tracking module recovers the pose of the stereo rig by solving a registration problem that naturally arises due to the chosen map and event data representation. experiments on publicly available datasets and on our own recordings demonstrate the versatility of the proposed method in natural scenes with general 6 - dof motion. the system successfully leverages the advantages of event - based cameras to perform visual odometry in challenging illumination conditions, such as low - light and high dynamic range, while running in real - time on a standard cpu. we release the software and dataset under an open source licence to foster research in the emerging topic of event - based slam.
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arxiv:2007.15548
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we provide an overview of the tools and techniques of resurgence theory used in the borel - ecalle resummation method, which we then apply to the massless wess - zumino model. starting from already known results on the anomalous dimension of the wess - zumino model, we solve its renormalisation group equation for the two point function in a space of formal series. we show that this solution is 1 - gevrey and that its borel transform is resurgent. the schwinger - dyson equation of the model is then used to prove an asymptotic exponential bound for the borel transformed two point function on a star - shaped domain of a suitable ramified complex plane. this prove that the two point function of the wess - zumino model is borel - ecalle summable.
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arxiv:1912.03237
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we investigate high resolution spectroscopic and imaging observations from the crisp imaging spectropolarimeter ( crisp ) instrument to study the dynamics of chromospheric spicule type events. it is widely accepted that chromospheric fine structures are waveguides for several types of magnetohydrodynamic ( mhd ) oscillations, which can transport energy from the lower to upper layers of the sun. we provide a statistical study of 30 high frequency waves associated with spicule type events. these high frequency oscillations have two components of transverse motions : the plane of sky ( pos ) motion and the line of sight ( los ) motion. we focus on single isolated spicules and track the pos using time distance analysis and in the los direction using doppler information. we use moment analysis to find the relation between the two motions. the composition of these two motions suggests that the wave has a helical structure. the oscillations do not have phase differences between points along the structure. this may be the result of the oscillation being a standing mode, or that propagation is mostly in the perpendicular direction. there is evidence of fast magnetoacoustic wave fronts propagating across these structures. to conclude, we hypothesize that the compression and rarefaction of passing magnetoacoustic waves may influence the appearance of spicule type events, not only by contributing to moving them in and out of the wing of the spectral line but also through the creation of density enhancements and an increase in opacity in the halpha line.
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arxiv:2112.14486
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detection and classification of objects in aerial imagery have several applications like urban planning, crop surveillance, and traffic surveillance. however, due to the lower resolution of the objects and the effect of noise in aerial images, extracting distinguishing features for the objects is a challenge. we evaluate centernet, a state of the art method for real - time 2d object detection, on the visdrone2019 dataset. we evaluate the performance of the model with different backbone networks in conjunction with varying resolutions during training and testing.
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arxiv:1908.08244
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many more nuclear transitions have to be known in the determination of stellar reactivities for trans - iron nucleosynthesis than for reactions of light nuclei. this requires different theoretical and experimental approaches. some of the issues specific for trans - iron nucleosynthesis are discussed.
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arxiv:1508.06569
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it has previously been shown heuristically that the topology of the universe affects gravity, in the sense that a test particle near a massive object in a multiply connected universe is subject to a topologically induced acceleration that opposes the local attraction to the massive object. this effect distinguishes different comoving 3 - manifolds, potentially providing a theoretical justification for the poincar \ ' e dodecahedral space observational hypothesis and a dynamical test for cosmic topology. it is necessary to check if this effect occurs in a fully relativistic solution of the einstein equations that has a multiply connected spatial section. a schwarzschild - like exact solution that is multiply connected in one spatial direction is checked for analytical and numerical consistency with the heuristic result. the t $ ^ 1 $ ( slab space ) heuristic result is found to be relativistically correct. for a fundamental domain size of $ l $, a slow - moving, negligible - mass test particle lying at distance $ x $ along the axis from the object of mass $ m $ to its nearest multiple image, where $ gm / c ^ 2 \ ll x \ ll l / 2 $, has a residual acceleration away from the massive object of $ 4 \ zeta ( 3 ) g ( m / l ^ 3 ) \, x $, where $ \ zeta ( 3 ) $ is ap \ ' ery ' s constant. for $ m \ sim 10 ^ 14 m _ \ odot $ and $ l \ sim 10 $ to $ 20 \ hgpc $, this linear expression is accurate to $ \ pm10 % $ over $ 3 \ hmpc \ ltapprox x \ ltapprox 2 \ hgpc $. thus, at least in a simple example of a multiply connected universe, the topological acceleration effect is not an artefact of newtonian - like reasoning, and its linear derivation is accurate over about three orders of magnitude in $ x $.
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arxiv:1109.1596
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we introduce an algorithm that constructs a discrete gradient field on any simplicial complex. we show that, in all situations, the gradient field is maximal possible and, in a number of cases, optimal. we make a thorough analysis of the resulting gradient field in the case of munkres ' discrete model for $ \ text { conf } ( k _ m, 2 ) $, the configuration space of ordered pairs of non - colliding particles on the complete graph $ k _ m $ on $ m $ vertices. together with the use of forman ' s discrete morse theory, this allows us to describe in full the cohomology $ r $ - algebra $ h ^ * ( \ text { conf } ( k _ m, 2 ) ; r ) $ for any commutative unital ring $ r $. as an application we prove that, although $ \ text { conf } ( k _ m, 2 ) $ is outside the " stable " regime, all its topological complexities are maximal possible when $ m \ geq4 $.
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arxiv:2207.07046
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we demonstrate the capability of growing high quality ultrathin films of the topological insulators bi2se3 and bi2te3 using molecular beam epitaxy. unlike previous growth techniques, which often pin the fermi energy in the conduction band for ultrathin samples, our samples remain intrinsic bulk insulators. we characterize these films using in - situ angle resolved photoemission spectroscopy ( arpes ), which is a direct probe of bandstructure, and ex - situ atomic force microscopy. we find that the conduction band lies above the fermi energy, indicating bulk insulating behavior with only the surface states crossing ef. we conclude that thermal cracking of te and se in our growth leads to higher quality thin films, paving the way for future improvements in growth of topological insulators.
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arxiv:1205.4258
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the gukov - manolescu series, denoted by $ f _ k $, is a conjectural invariant of knot complements that, in a sense, analytically continues the colored jones polynomials. in this paper we use the large color $ r $ - matrix to study $ f _ k $ for some simple links. specifically, we give a definition of $ f _ k $ for positive braid knots, and compute $ f _ k $ for various knots and links. as a corollary, we present a class of ` strange identities ' for positive braid knots.
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arxiv:2004.02087
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in this paper, we will present advanced discretization methods for solving retarded potential integral equations. we employ a $ c ^ { \ infty } $ - partition of unity method in time and a conventional boundary element method for the spatial discretization. one essential point for the algorithmic realization is the development of an efficient method for approximation the elements of the arising system matrix. we present here an approach which is based on quadrature for ( non - analytic ) $ c ^ { \ infty } $ functions in combination with certain chebyshev expansions. furthermore we introduce an a posteriori error estimator for the time discretization which is employed also as an error indicator for adaptive refinement. numerical experiments show the fast convergence of the proposed quadrature method and the efficiency of the adaptive solution process.
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arxiv:1404.2322
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face anti - spoofing ( fas ) is pivotal in safeguarding facial recognition systems against presentation attacks. while domain generalization ( dg ) methods have been developed to enhance fas performance, they predominantly focus on learning domain - invariant features during training, which may not guarantee generalizability to unseen data that differs largely from the source distributions. our insight is that testing data can serve as a valuable resource to enhance the generalizability beyond mere evaluation for dg fas. in this paper, we introduce a novel test - time domain generalization ( ttdg ) framework for fas, which leverages the testing data to boost the model ' s generalizability. our method, consisting of test - time style projection ( ttsp ) and diverse style shifts simulation ( dsss ), effectively projects the unseen data to the seen domain space. in particular, we first introduce the innovative ttsp to project the styles of the arbitrarily unseen samples of the testing distribution to the known source space of the training distributions. we then design the efficient dsss to synthesize diverse style shifts via learnable style bases with two specifically designed losses in a hyperspherical feature space. our method eliminates the need for model updates at the test time and can be seamlessly integrated into not only the cnn but also vit backbones. comprehensive experiments on widely used cross - domain fas benchmarks demonstrate our method ' s state - of - the - art performance and effectiveness.
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arxiv:2403.19334
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in collision - poor space plasmas protons with an excess of kinetic energy or temperature in direction perpendicular to background magnetic field can excite the electromagnetic ion cyclotron ( emic ) instability. this instability is expected to be highly sensitive to suprathermal protons, which enhance the high - energy tails of the observed velocity distributions and are well reproduced by the ( bi - ) kappa distribution functions. in this paper we present the results of a refined quasilinear ( ql ) approach, able to describe the effects of suprathermal protons on the extended temporal evolution of emic instability. it is thus shown that suprathermals have a systematic stimulating effect on the emic instability, enhancing not only the growth rates and the range of unstable wave - numbers, but also the magnetic fluctuating energy density reached at the saturation. in effect, the relaxation of anisotropic temperature becomes also more efficient, i. e., faster in time and closer to isotropy.
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arxiv:2012.09899
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we show that $ \ mathbb { q } $ - fano varieties of fixed dimension with anti - canonical degrees and alpha - invariants bounded from below form a bounded family. as a corollary, k - semistable $ \ mathbb { q } $ - fano varieties of fixed dimension with anti - canonical degrees bounded from below form a bounded family.
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arxiv:1705.02740
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in the late eighties john kingman studied the problem of maxima of a quadratic form, with independent, uniformly distributed, coefficients, on a simplex of growing dimension $ n $. in particular, he proved that the largest support size ( cardinality ) $ l _ n $ of a potential local maximum is, in probability, $ 2. 49 n ^ { 1 / 2 } $ at most, and for a non - biological case of independent exponentials on $ [ 0, \ infty ) $ he reduced the constant to $ 2. 14 $. in this paper we show that the constant $ 2. 14 $ serves a broad class of the densities on $ [ 0, 1 ] $, which includes a linear non - decreasing ( whence uniform ) density and the exponential density conditioned on $ [ 0, 1 ] $. we also prove a qualitatively matching lower bound : in probability, $ l _ n \ ge 2n ^ { 1 / 3 } $ at least. our argument shows also that the random counts of potential maxima supports, whose sizes range from $ 2 $ to $ \ lceil 2n ^ { 1 / 3 } \ rceil $, are asymptotic to their expected values. finally we show that a support of a local maximum, that does not contain a support of a local equilibrium, is very unlikely to have size exceeding $ 2 \ log _ 2 n $.
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arxiv:1708.03255
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in this paper, we are interested in an inverse problem for the active scalar equations with fractional dissipation on the torus. our argument relies on the divergence - free structure in the nonlinear term, the second order linearization, the unique continuation property of the fractional laplacian and its associated runge approximation property.
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arxiv:2412.03868
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we consider an electron, spin 1 / 2, minimally coupled to the quantized radiation field in the nonrelativistic approximation, a situation defined by the pauli - fierz hamiltonian $ h $. there is no external potential and $ h $ fibers as $ \ int ^ \ oplus h _ p dp $ according to the total momentum $ p $. we prove that the ground state subspace of $ h _ p $ is two - fold degenerate provided the charge $ e $ and the total momentum $ p $ are sufficiently small. we also establish that the total angular momentum of the ground state subspace is $ \ pm1 / 2 $ and study the case of a confining external potential.
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arxiv:math-ph/0210052
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in this work, we investigate the commutative monoids over which the axiomatizable class of regular s - acts is primitive normal and antiadditive. we prove that the primitive normality of an axiomatizable class of regular s - acts over the commutative monoid s is equivalent to the antiadditivity of this class and it is equivalent to the linearity of the order on a semigroup r such that an s - act sr is a maximal ( under the inclusion ) regular subact of the s - act ss.
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arxiv:1804.09353
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we performed an optical / infrared study of the counterpart of the low - mass x - ray binary ks1731 - 260 to test its identification and obtain information about the donor. optical and infrared images of the counterpart of ks1731 - 260 were taken in two different epochs ( 2001 and 2007 ) after the source returned to quiescence in x - rays. we compared those observations with obtained when ks 1731 - 260 was still active. we confirm the identification of ks1731 - 260 with the previously proposed counterpart and improve its position to ra = 17 : 34 : 13. 46 and dec = - 26 : 05 : 18. 60. the h - band magnitude of this candidate showed a decline of ~ 1. 7 mags from outburst to quiescence. in 2007 april we obtained r = 22. 8 + - 0. 1 and i = 20. 9 + - 0. 1 for ks1731 - 260. similar optical brightness was measured in june 2001 and july 2007. the intrinsic optical color r - i is consistent with spectral types from f to g for the secondary although there is a large excess over that from the secondary at the infrared wavelengths. this may be due to emission from the cooler outer regions of the accretion disk. we cannot rule out a brown dwarf as a donor star, although it would require that the distance to the source is significantly lower than the 7 kpc reported by muno et al. 2000.
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arxiv:1001.2273
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an image plate ( ip ) detector coupled with high energy synchrotron radiation was used for atomic pair distribution function ( pdf ) analysis, with high probed momentum transfer \ qmax $ \ leq 28. 5 $ \ raa from crystalline materials. materials with different structural complexities were measured to test the validity of the quantitative data analysis. experimental results are presented here for crystalline ni, crystalline \ alf, and the layered aurivillius type oxides \ bivo and \ bivtio. overall, the diffraction patterns show good counting statistics with measuring time from one to tens of seconds. the pdfs obtained are of high quality. structures may be refined from these pdfs, and the structural models are consistent with the published literature. data sets from similar samples are highly reproducible.
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arxiv:cond-mat/0304638
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this paper is devoted to the anomalous diffusion limit of kinetic equations with a fractional fokker - planck collision operator in a spatially bounded domain. we consider two boundary conditions at the kinetic scale : absorption and specular reflection. in the absorption case, we show that the long time / small mean free path asymptotic dynamics are described by a fractional diffusion equation with homogeneous dirichlet - type boundary conditions set on the whole complement of the spatial domain. on the other hand, specular reflections will give rise to a new operator which we call specular diffusion operator and write $ ( - \ delta ) _ { \ text { sr } } ^ s $. this non - local diffusion operator strongly depends on the geometry of the domain and includes in its definition the interaction between the diffusion and the boundary. we consider two types of domains : half - spaces and balls in $ \ mathbb { r } ^ d $. in these domains, we prove properties of the specular diffusion operator and establish existence and uniqueness of weak solutions to the associated heat - type equation.
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arxiv:1611.06372
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the implications from the existence of a proper homothetic vector field ( hvf ) on the dynamics of vacuum anisotropic models in $ f ( r ) $ gravitational theory are studied. the fact that \ emph { every } spatially homogeneous vacuum model is equivalent, formally, with a " flux " - free anisotropic fluid model in standard gravity and the induced power - law form of the functional $ f ( r ) $ due to self - similarity enable us to close the system of equations. we found some new exact anisotropic solutions that arise as fixed points in the associated dynamical system. the non - existence of kasner - like ( bianchi type i ) solutions in proper $ f ( r ) - $ gravity ( i. e. $ r \ neq 0 $ ) strengthens the belief that curvature corrections will prevent the shear influence into the past thus permitting an isotropic singularity. we also discuss certain issues regarding the lack of vacuum models of type iii, iv, vii $ _ { h } $ in comparison with the corresponding results in standard gravity.
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arxiv:1611.02013
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that political newspapers which enjoyed the widest popularity reach up to 250, 000 readers in the holy roman empire, around one quarter of the literate population. air - gun in 1607 bartolomeo crescentio described an air gun equipped with a powerful spiral spring, a device so complex that it must have had predecessors. in 1610 mersenne spoke in detail of " sclopeti pneumatici constructio ", and four years later wilkins wrote enthusiastically of " that late ingenious invention the wind - gun " as being " almost equall to our powder - guns ". in the 1650s otto von guericke, famed for his experiments with vacua and pressures, built the madeburger windbuchse, one of the technical wonders of its time. = = tools, devices, work processes = = = = = 15th century = = = cranked archimedes ' screw the german engineer konrad kyeser equips in his bellifortis ( 1405 ) the archimedes ' screw with a crank mechanism which soon replaces the ancient practice of working the pipe by treading. cranked reel in the textile industry, cranked reels for winding skeins of yarn were introduced in the early 15th century. brace the earliest carpenter ' s braces equipped with a u - shaped grip, that is with a compound crank, appears between 1420 and 1430 in flanders. cranked well - hoist the earliest evidence for the fitting of a well - hoist with cranks is found in a miniature of c. 1425 in the german hausbuch of the mendel foundation. paddle wheel boat powered by crank and connecting rod mechanism while paddle wheel boats powered by manually turned crankshafts were already conceived of by earlier writers such as guido da vigevano and the anonymous author of the hussite wars, the italian roberto valturio much improves on the design in 1463 by devising a boat with five sets of parallel cranks which are all joined to a single power source by one connecting rod ; the idea is also taken up by his compatriot francesco di giorgio. rotary grindstone with treadle evidence for rotary grindstones operated by a crank handle goes back to the carolingian utrecht psalter. around 1480, the crank mechanism is further mechanized by adding a treadle. geared hand - mill the geared hand - mill, operated either with one or two cranks, appears in the 15th century. = = = 16th century = = = grenade mu
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https://en.wikipedia.org/wiki/Renaissance_technology
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we consider a market impact game for $ n $ risk - averse agents that are competing in a market model with linear transient price impact and additional transaction costs. for both finite and infinite time horizons, the agents aim to minimize a mean - variance functional of their costs or to maximize the expected exponential utility of their revenues. we give explicit representations for corresponding nash equilibria and prove uniqueness in the case of mean - variance optimization. a qualitative analysis of these nash equilibria is conducted by means of numerical analysis.
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arxiv:1807.03813
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we construct new classes of the dynamical black hole solutions in five or higher dimensional einstein - maxwell theory, coupled to a dilaton field, in the presence of arbitrary cosmological constant. the dilaton field interacts non - trivially with the maxwell field, as well as the cosmological constant, with two arbitrary coupling constants. the solutions are non - stationary, and almost conformally regular everywhere. to construct the solutions, we use the four - dimensional bianchi type ix geometry, as the base space. we find three different classes of solutions, based on the values of the coupling constants. we notice that our solutions could be asymptotically de - sitter, anti - de - sitter or flat. we find the relevant quantities of the solutions, and discuss the properties of the solutions.
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arxiv:2501.07495
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packing and covering linear programs belong to the narrow class of linear programs that are efficiently solvable in parallel and distributed models of computation, yet are a powerful modeling tool for a wide range of fundamental problems in theoretical computer science, operations research, and many other areas. following recent progress in obtaining faster distributed and parallel algorithms for packing and covering linear programs, we present a simple algorithm whose iteration count matches the best known $ \ tilde { o } ( \ frac { 1 } { \ epsilon ^ 2 } ) $ for this class of problems. the algorithm is similar to the algorithm of [ allen - zhu and orecchia, 2015 ], it can be interpreted as nesterov ' s dual averaging, and it constructs approximate solutions to both primal ( packing ) and dual ( covering ) problems. however, the analysis relies on the construction of an approximate optimality gap and a primal - dual view, leading to a more intuitive interpretation. moreover, our analysis suggests that all existing algorithms for solving packing and covering linear programs in parallel / distributed models of computation are, in fact, unaccelerated, and raises the question of designing accelerated algorithms for this class of problems.
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arxiv:1710.09002
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we review the moyal and wick - voros products, and more in general the translation invariant non - commutative products, and apply them to classical and quantum field theory. we investigate phi ^ 4 field theories calculating their green ' s functions up to one - loop for the two - and four - point cases. we also review the connections of these theories with drinfeld twists.
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arxiv:1004.4655
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we give an entire free holomorphic function $ f $ which is unbounded on the row ball. that is, we give a holomorphic free noncommutative function which is continuous in the free topology developed by agler and mccarthy but is unbounded on the set of row contractions.
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arxiv:1908.06753
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we prove a surprising higher regularity for solutions to the nonlinear elliptic autonomous beltrami equation in a planar domain $ \ omega $, \ [ f _ \ zbar = { \ cal a } ( f _ z ) \ hskip15pt a. e. \ ; \ ; z \ in \ omega, \ ] when $ { \ cal a } $ is linear at $ \ infty $. namely $ w ^ { 1, 1 } _ { loc } ( \ omega ) $ solutions are $ w ^ { 2, 2 + \ epsilon } _ { loc } ( \ omega ) $. here $ \ epsilon > 0 $ depends explicitly on the ellipticity bounds of $ { \ cal a } $. the condition ` ` is linear at $ \ infty $ ' ' is necessary - the result is false for the equation $ f _ \ zbar = k | f _ z | $, for any $ 0 < k < 1 $, ( $ k = 0 $ is weyl ' s lemma ). we discuss the subsequent higher regularity implications for fully non - linear beltrami systems.
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arxiv:1903.01008
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we present a detailed study of ngc 6791, ngc 6811, ngc 6819 and ngc 6866, the four open clusters that are located in the kepler prime field. we use new ccd ubv ( ri ) kc photometry, which was combined with gaia edr3 photometric / astrometric data, to derive the astrophysical parameters with two independent methods - one of them the fitcmd algorithm. furthermore, we provide among others estimates of the mass and mass function, the cluster structure, derive the cluster orbits, and discuss the cluster dynamics. all objects belong to the older open cluster population ( 1 - 7gyr ), are in an advanced dynamical stage with signs of mass segregation, and are located close to the solar circle, but show a large range in respect of radii, member stars or observed cluster mass ( 100 - 2000 msolar ). for the three younger objects we were also able to provide photometric metallicity estimates, which confirms their status as clusters with a roughly solar metallicity. the most outstanding object is clearly ngc 6791, a very old cluster with a high metallicity at a distance of about 4. 5 kpc from the sun. we estimate a probable radial migration by about 7 kpc, resulting in a birth position close to the galactic center.
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arxiv:2302.09851
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we complete a minor gap in gromoll and walschap classification of metric fibrations from the euclidean space, thus completing the classification of riemannian foliations on euclidean spaces.
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arxiv:1806.09580
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under the assumptions that 1 ) the quark / lepton mass matrices take froggatt - nielsen ' s factorized power form \ lambda ^ { \ psi _ i + \ psi _ j } with anomalous u ( 1 ) charges \ psi _ i, and 2 ) the u ( 1 ) charges \ psi _ i respect the su ( 5 ) gut structure, we show that the quark mass data necessarily implies the large 2 - 3 mixing in the mns mixing matrix u _ { mns }. if we further add the data of the mass squared difference ratio of solar and atmospheric neutrinos, then, it implies that the 1 - 2 mixing in u _ { mns } is also large, so explaining the bi - large mixing. this analysis also gives a prediction that u _ { e3 } \ equiv ( u _ { \ rm mns } ) _ { 13 } should be of order \ lambda \ sim ( 0. 1 - 0. 5 ).
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arxiv:hep-ph/0306035
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automatic modulation recognition ( amr ) is vital for accurately identifying modulation types within incoming signals, a critical task for optimizing operations within edge devices in iot ecosystems. this paper presents an innovative approach that leverages transformer networks, initially designed for natural language processing, to address the challenges of efficient amr. our transformer network architecture is designed with the mindset of real - time edge computing on iot devices. four tokenization techniques are proposed and explored for creating proper embeddings of rf signals, specifically focusing on overcoming the limitations related to the model size often encountered in iot scenarios. extensive experiments reveal that our proposed method outperformed advanced deep learning techniques, achieving the highest recognition accuracy. notably, our model achieves an accuracy of 65. 75 on the rml2016 and 65. 80 on the cspb. ml. 2018 + dataset.
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arxiv:2403.15417
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we present details of the analytic computation of the spectrum of lowest spin glueballs in pure yang - mills theory in 2 + 1 dimensions. the new ingredient is provided by the conjectured new non - trivial expression for the ( quasi ) gaussian part of the ground state wave - functional. we show that this wave - functional can be derived by solving the schrodinger equation under certain assumptions. the mass spectrum of the theory is determined by the zeros of bessel functions, and the agreement with available lattice data is excellent.
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arxiv:hep-th/0604060
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the most popular noncommutative field theories are characterized by a matrix parameter theta ^ ( mu, nu ) that violates lorentz invariance. we consider the simplest algebra in which the theta - parameter is promoted to an operator and lorentz invariance is preserved. this algebra arises through the contraction of a larger one for which explicit representations are already known. we formulate a star product and construct the gauge - invariant lagrangian for lorentz - conserving noncommutative qed. three - photon vertices are absent in the theory, while a four - photon coupling exists and leads to a distinctive phenomenology.
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arxiv:hep-th/0206035
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due to 5g millimeter wave ( mmwave ), spatial channel parameters are becoming highly resolvable, enabling accurate vehicle localization and mapping. we propose a novel method of radio simultaneous localization and mapping ( slam ) with the dirichlet process ( dp ). the dp, which can estimate the number of clusters as well as clustering, is capable of identifying the locations of reflectors by classifying signals when such 5g signals are reflected and received from various objects. we generate birth points using the measurements from 5g mmwave signals received by the vehicle and classify objects by clustering birth points generated over time. each time we use the dp clustering method, we can map landmarks in the environment in challenging situations where false alarms exist in the measurements and change the cardinality of received signals. simulation results demonstrate the performance of the proposed scheme. by comparing the results with the slam based on the rao - blackwellized probability hypothesis density filter, we confirm a slight drop in slam performance, but as a result, we validate that it has a significant gain in computational complexity.
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arxiv:2107.00864
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we study the impact of quantum computation on the fundamental problem of testing the property of distributions. in particular, we focus on testing whether two unknown classical distributions are close or far enough, and propose the currently best quantum algorithms for this problem under the metrics of $ l ^ 1 $ - distance and $ l ^ 2 $ - distance. compared with the latest results given in \ cite { gilyen2019distributional } which relied on the technique of quantum singular value transformation ( qsvt ), our algorithms not only have lower complexity, but also are more concise.
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arxiv:2302.06084
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while magnetic fields likely play an important role in driving the evolution of protoplanetary disks through angular momentum transport, observational evidence of magnetic fields has only been found in a small number of disks. although dust continuum linear polarization has been detected in an increasing number of disks, its pattern is more consistent with that from dust scattering than from magnetically aligned grains in the vast majority of cases. continuum linear polarization from dust grains aligned to a magnetic field can reveal information about the magnetic field ' s direction, but not its strength. on the other hand, observations of circular polarization in molecular lines produced by zeeman splitting offer a direct measure of the line - of - sight magnetic field strength in disks. we present upper limits on the net toroidal and vertical magnetic field strengths in the protoplanetary disk as 209 derived from zeeman splitting observations of the cn 2 - 1 line. the 3 $ \ sigma $ upper limit on the net line - of - sight magnetic field strength in as 209 is 5. 0 mg on the redshifted side of the disk and 4. 2 mg on the blueshifted side of the disk. given the disk ' s inclination angle, we set a 3 $ \ sigma $ upper limit on the net toroidal magnetic field strength of 8. 7 and 7. 3 mg for the red and blue sides of the disk, respectively, and 6. 2 and 5. 2 mg on the net vertical magnetic field on the red and blue sides of the disk. if magnetic disk winds are a significant mechanism of angular momentum transport in the disk, magnetic fields of a strength close to the upper limits would be sufficient to drive accretion at the rate previously inferred for regions near the protostar.
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arxiv:2101.01846
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we calculate the friction experienced by ultrarelativistic bubble walls resulting from the $ 1 \ rightarrow 2 $ light - to - heavy transition process, with finite - wall - width effects fully taken into account. in this process, the light particle is excited from the order - parameter scalar field, while the two heavy particles are excitations of a dark matter scalar field. unlike earlier estimates suggesting a friction scaling as $ \ gamma _ w ^ 0 $, where $ \ gamma _ w $ represents the lorentz factor of the wall velocity, our more precise numerical analysis reveals a logarithmic dependence of the friction on $ \ gamma _ w $. we offer a numerical fit to capture this frictional pressure accurately. our analysis verifies that the friction stemming from the $ 1 \ rightarrow 2 $ light - to - heavy transition is typically much smaller than the friction from the $ 1 \ rightarrow 1 $ transmission of the dark matter particles.
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arxiv:2308.10679
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spiking neuron networks have been used successfully to solve simple reinforcement learning tasks with continuous action set applying learning rules based on spike - timing - dependent plasticity ( stdp ). however, most of these models cannot be applied to reinforcement learning tasks with discrete action set since they assume that the selected action is a deterministic function of firing rate of neurons, which is continuous. in this paper, we propose a new stdp - based learning rule for spiking neuron networks which contains feedback modulation. we show that the stdp - based learning rule can be used to solve reinforcement learning tasks with discrete action set at a speed similar to standard reinforcement learning algorithms when applied to the cartpole and lunarlander tasks. moreover, we demonstrate that the agent is unable to solve these tasks if feedback modulation is omitted from the learning rule. we conclude that feedback modulation allows better credit assignment when only the units contributing to the executed action and td error participate in learning.
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arxiv:2008.13044
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we discuss the growth of the lebesgue constants for polynomial interpolation at fekete points for fixed degree ( one ) and varying dimension, and underlying set $ k \ subset \ r ^ d $ a simplex, ball or cube.
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arxiv:2305.01699
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coefficients of a series are quite arbitrary, a function that is the sum of a convergent series is generally defined otherwise, and the sequence of the coefficients is the result of some computation based on another definition. then, the power series can be used to enlarge the domain of the function. typically, if a function for a real variable is the sum of its taylor series in some interval, this power series allows immediately enlarging the domain to a subset of the complex numbers, the disc of convergence of the series. then analytic continuation allows enlarging further the domain for including almost the whole complex plane. this process is the method that is generally used for defining the logarithm, the exponential and the trigonometric functions of a complex number. = = = by recurrence = = = functions whose domain are the nonnegative integers, known as sequences, are sometimes defined by recurrence relations. the factorial function on the nonnegative integers ( n ↦ n! { \ displaystyle n \ mapsto n! } ) is a basic example, as it can be defined by the recurrence relation n! = n ( n − 1 )! for n > 0, { \ displaystyle n! = n ( n - 1 )! \ quad { \ text { for } } \ quad n > 0, } and the initial condition 0! = 1. { \ displaystyle 0! = 1. } = = representing a function = = a graph is commonly used to give an intuitive picture of a function. as an example of how a graph helps to understand a function, it is easy to see from its graph whether a function is increasing or decreasing. some functions may also be represented by bar charts. = = = graphs and plots = = = given a function f : x → y, { \ displaystyle f : x \ to y, } its graph is, formally, the set g = { ( x, f ( x ) ) x ∈ x }. { \ displaystyle g = \ { ( x, f ( x ) ) \ mid x \ in x \ }. } in the frequent case where x and y are subsets of the real numbers ( or may be identified with such subsets, e. g. intervals ), an element ( x, y ) ∈ g { \ displaystyle ( x, y ) \ in g } may be identified with a point having coordinates x, y in a 2 - dimensional coordinate system, e. g. the
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https://en.wikipedia.org/wiki/Function_(mathematics)
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we compute the 1 - loop ( alpha _ s ^ 2 ) correction to hard spectator scattering in non - leptonic b decay tree amplitudes. this forms part of the nnlo contribution to the qcd factorization formula for hadronic b decays, and introduces a new rescattering phase that corrects the leading - order result for direct cp asymmetries. among the technical issues, we discuss the cancellation of infrared divergences, and the treatment of evanescent four - quark operators. the infrared finiteness of our result establishes factorization of spectator scattering at the 1 - loop order. depending on the values of hadronic input parameters, the new 1 - loop correction may have a significant impact on tree - dominated decays such as b - > pi pi.
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arxiv:hep-ph/0512351
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understanding a user ' s motivations provides valuable information beyond the ability to recommend items. quite often this can be accomplished by perusing both ratings and review texts, since it is the latter where the reasoning for specific preferences is explicitly expressed. unfortunately matrix factorization approaches to recommendation result in large, complex models that are difficult to interpret and give recommendations that are hard to clearly explain to users. in contrast, in this paper, we attack this problem through succinct additive co - clustering. we devise a novel bayesian technique for summing co - clusterings of poisson distributions. with this novel technique we propose a new bayesian model for joint collaborative filtering of ratings and text reviews through a sum of simple co - clusterings. the simple structure of our model yields easily interpretable recommendations. even with a simple, succinct structure, our model outperforms competitors in terms of predicting ratings with reviews.
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arxiv:1512.01845
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we study the topological susceptibility and fourth cumulant of the qcd vacuum in a background magnetic field using three - flavor chiral perturbation theory ( $ \ chi $ pt ) for arbitrary quark masses and $ n $ - flavor $ \ chi $ pt with degenerate quark masses. we find that the enhancement of the topological susceptibility is larger in the three - flavor $ \ chi $ pt compared to two - flavor $ \ chi $ pt. additionally, in comparing the fourth cumulant, we find that its suppression is comparable for magnetic fields, $ eh \ lesssim 0. 8m _ { \ pi } ^ { 2 } $, and weaker for larger magnetic fields in three - flavor $ \ chi $ pt with its enhancement beginning at a significantly lower critical magnetic field compared to two - flavor $ \ chi $ pt. we also find that the enhancement of the topological susceptibility in $ n $ - flavor $ \ chi $ pt with degenerate quarks is significantly larger and the suppression of the topological cumulant significantly greater at weak fields with the critical magnetic field pushed out to larger magnetic fields compared to both two and three - flavor $ \ chi $ pt.
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arxiv:2203.00200
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copula modelling has become ubiquitous in modern statistics. here, the problem of nonparametrically estimating a copula density is addressed. arguably the most popular nonparametric density estimator, the kernel estimator is not suitable for the unit - square - supported copula densities, mainly because it is heavily affected by boundary bias issues. in addition, most common copulas admit unbounded densities, and kernel methods are not consistent in that case. in this paper, a kernel - type copula density estimator is proposed. it is based on the idea of transforming the uniform marginals of the copula density into normal distributions via the probit function, estimating the density in the transformed domain, which can be accomplished without boundary problems, and obtaining an estimate of the copula density through back - transformation. although natural, a raw application of this procedure was, however, seen not to perform very well in the earlier literature. here, it is shown that, if combined with local likelihood density estimation methods, the idea yields very good and easy to implement estimators, fixing boundary issues in a natural way and able to cope with unbounded copula densities. the asymptotic properties of the suggested estimators are derived, and a practical way of selecting the crucially important smoothing parameters is devised. finally, extensive simulation studies and a real data analysis evidence their excellent performance compared to their main competitors.
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arxiv:1404.4414
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in this paper we present several new and very practical methods and techniques for range aggregation and selection problems in multidimensional data structures and other types of sets of values. we also present some new extensions and applications for some fundamental set maintenance problems.
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arxiv:1006.3968
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for the past decade, temporal annotation has been sparse : only a small portion of event pairs in a text was annotated. we present narrativetime, the first timeline - based annotation framework that achieves full coverage of all possible tlinks. to compare with the previous sota in dense temporal annotation, we perform full re - annotation of timebankdense corpus, which shows comparable agreement with a significant increase in density. we contribute timebanknt corpus ( with each text fully annotated by two expert annotators ), extensive annotation guidelines, open - source tools for annotation and conversion to timeml format, baseline results, as well as quantitative and qualitative analysis of inter - annotator agreement.
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arxiv:1908.11443
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this study evaluates the capability of vision - language models ( vlms ) in image data annotation by comparing their performance on the celeba dataset in terms of quality and cost - effectiveness against manual annotation. annotations from the state - of - the - art llava - next model on 1000 celeba images are in 79. 5 % agreement with the original human annotations. incorporating re - annotations of disagreed cases into a majority vote boosts ai annotation consistency to 89. 1 % and even higher for more objective labels. cost assessments demonstrate that ai annotation significantly reduces expenditures compared to traditional manual methods - - representing less than 1 % of the costs for manual annotation in the celeba dataset. these findings support the potential of vlms as a viable, cost - effective alternative for specific annotation tasks, reducing both financial burden and ethical concerns associated with large - scale manual data annotation. the ai annotations and re - annotations utilized in this study are available on https : / / github. com / evev2024 / evev2024 _ celeba.
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arxiv:2410.09416
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molecular models of real fluids are validated by comparing the vapor - liquid surface tension from molecular dynamics ( md ) simulation to correlations of experimental data. the considered molecular models consist of up to 28 interaction sites, including lennard - jones sites, point charges, dipoles and quadrupoles. they represent 38 real fluids, such as ethylene oxide, sulfur dioxide, phosgene, benzene, ammonia, formaldehyde, methanol and water, and were adjusted to reproduce the saturated liquid density, vapor pressure and enthalpy of vaporization. the models were not adjusted to interfacial properties, however, so that the present md simulations are a test of model predictions. it is found that all of the considered models overestimate the surface tension. in most cases, however, the relative deviation between the simulation results and correlations to experimental data is smaller than 20 %. this observation corroborates the outcome of our previous studies on the surface tension of 2cljq and 2cljd fluids where an overestimation of the order of 10 to 20 % was found.
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arxiv:1608.04193
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electron spin qubits are a promising platform for quantum computation. environmental noise impedes coherent operations by limiting the qubit relaxation ( $ t _ 1 $ ) and dephasing ( $ t _ { \ phi } $ ) times. there are multiple sources of such noise, which makes it important to devise experimental techniques that can detect the spatial locations of these sources and determine the type of source. in this paper, we propose that anisotropy in $ t _ 1 $ and $ t _ { \ phi } $ with respect to the direction of the applied magnetic field can reveal much about these aspects of the noise. we investigate the anisotropy patterns of charge noise, evanescent - wave johnson noise, and hyperfine noise in hypothetical devices. it is necessary to have a rather well - characterized sample to get the maximum benefit from this technique. the general anisotropy patterns are elucidated. we calculate the expected anisotropy for a particular model of a si / sige quantum dot device.
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arxiv:2103.05865
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we find that the antiferromagnetic heisenberg model on the kagome lattice with nearest neighboring exchange coupling ( nn - kafh ) belongs to a continuous family of fully - frustrated heisenberg model on the kagome lattice, which has no preferred classical ordering pattern. the model within this family consists of the first, second and the third neighboring exchange coupling $ j _ { 1 } $, $ j _ { 2 } $, and $ j _ { 3 } $, with $ j _ { 2 } = j _ { 3 } $. we find that when $ - j _ { 1 } \ leq j _ { 2 } = j _ { 3 } \ leq 0. 2j _ { 1 } $, the lowest band of $ j ( \ mathbf { q } ) $, namely, the fourier transform of the exchange coupling, is totally non - dispersive. exact diagonalization calculation indicates that the ground state of the spin - $ \ frac { 1 } { 2 } $ nn - kafh is locally stable under the perturbation of $ j _ { 2 } $ and $ j _ { 3 } $ when and only when $ j _ { 2 } = j _ { 3 } $. interestingly, we find that the same flat band physics is also playing an important role in the rvb description of the spin liquid state on the kagome lattice. in particular, we show that the extensively studied $ u ( 1 ) $ dirac spin liquid state on the kagome lattice can actually be generated from a continuous family of gauge inequivalent rvb mean field ansatz, which host very different mean field spinon dispersion.
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arxiv:1805.07689
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when humans perform a task with an articulated object, they interact with the object only in a handful of ways, while the space of all possible interactions is nearly endless. this is because humans have prior knowledge about what interactions are likely to be successful, i. e., to open a new door we first try the handle. while learning such priors without supervision is easy for humans, it is notoriously hard for machines. in this work, we tackle unsupervised learning of priors of useful interactions with articulated objects, which we call interaction modes. in contrast to the prior art, we use no supervision or privileged information ; we only assume access to the depth sensor in the simulator to learn the interaction modes. more precisely, we define a successful interaction as the one changing the visual environment substantially and learn a generative model of such interactions, that can be conditioned on the desired goal state of the object. in our experiments, we show that our model covers most of the human interaction modes, outperforms existing state - of - the - art methods for affordance learning, and can generalize to objects never seen during training. additionally, we show promising results in the goal - conditional setup, where our model can be quickly fine - tuned to perform a given task. we show in the experiments that such affordance learning predicts interaction which covers most modes of interaction for the querying articulated object and can be fine - tuned to a goal - conditional model. for supplementary : https : / / actaim. github. io.
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arxiv:2305.17565
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we review the modern classical electrodynamics problems and present the related main fundamental principles characterizing the electrodynamical vacuum - field structure. we analyze the models of the vacuum field medium and charged point particle dynamics using the developed field theory concepts. there is also described a new approach to the classical maxwell theory based on the derived and newly interpreted basic equations making use of the vacuum field theory approach. in particular, there are obtained the main classical special relativity theory relations and their new explanations. the well known feynman approach to maxwell electromagnetic equations and the lorentz type force derivation is also discussed in detail. a related charged point particle dynamics and a hadronic string model analysis is also presented. we also revisited and reanalyzed the classical lorentz force expression in arbitrary non - inertial reference frames and present some new interpretations of the relations between special relativity theory and its quantum mechanical aspects. some results related with the charge particle radiation problem and the magnetic potential topological aspects are discussed. the electromagnetic dirac - fock - podolsky problem of the maxwell and yang - mills type dynamical systems is analyzed within the classical dirac - marsden - weinstein symplectic reduction theory. the problem of constructing fock type representations and retrieving their creation - annihilation operator structure is analyzed. an application of the suitable current algebra representation to describing the non - relativistic aharonov - bohm paradox is presented. the current algebra coherent functional representations are constructed and their importance subject to the linearization problem of nonlinear dynamical systems in hilbert spaces is demonstrated.
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arxiv:1204.5129
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we present a self - attention based bilingual adversarial text generator ( b - gan ) which can learn to generate text from the encoder representation of an unsupervised neural machine translation system. b - gan is able to generate a distributed latent space representation which can be paired with an attention based decoder to generate fluent sentences. when trained on an encoder shared between two languages and paired with the appropriate decoder, it can generate sentences in either language. b - gan is trained using a combination of reconstruction loss for auto - encoder, a cross domain loss for translation and a gan based adversarial loss for text generation. we demonstrate that b - gan, trained on monolingual corpora only using multiple losses, generates more fluent sentences compared to monolingual baselines while effectively using half the number of parameters.
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arxiv:2011.05449
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the n = 2 supersymmetric { \ alpha } = 1 kdv hierarchy in n = 2 superspace is considered and its rich symmetry structure is uncovered. new nonpolynomial and nonlocal, bosonic and fermionic symmetries and hamiltonians, bi - hamiltonian structure as well as a recursion operator connecting all symmetries and hamiltonian structures of the n = 2 { \ alpha } = 1 kdv hierarchy are constructed in explicit form. it is observed that the algebra of symmetries of the n = 2 supersymmetric { \ alpha } = 1 kdv hierarchy possesses two different subalgebras of n = 2 supersymmetry.
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arxiv:nlin/0201061
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in this paper, we investigate properties of the bounded derived category of finite dimensional modules over a gentle or skew - gentle algebra. we show that the rouquier dimension of the derived category of such an algebra is at most one. using this result, we prove that the rouquier dimension of an arbitrary tame projective curve is equal to one, too. finally, we elaborate the classification of indecomposable objects of the ( possibly unbounded ) homotopy category of projective modules of a gentle algebra.
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arxiv:1706.08358
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we investigate the prospects for detecting and constraining density and temperature inhomogeneities in the circumgalactic medium ( cgm ) using absorption measurements of metal ions. distributions in the gas thermal properties could arise from turbulence, gas cooling from the hot phase, and mixing between the cool and hot phases. focusing on these physically motivated models, we parameterize each with a single parameter for simplicity and provide empirical and theoretical estimates for reasonable parameter values. we then construct the probability distribution functions for each of these scenarios, calculate the effective ion fractions, and fit our models to the cos - halos absorption measurements to infer the gas densities and metallicities. we find that the models we consider ( i ) produce similarly good fits to the observations with or without distributions in the gas thermal properties, and ( ii ) result in detectable changes in the column densities only at the boundaries of reasonable parameter values. we show that he ii self - shielding can have a larger effect on the ion fractions than density and temperature fluctuations. as a result, uncertainties in cloud geometry and their spatial distribution, affecting the details of radiation transfer, may obscure the effect of inhomogeneities.
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arxiv:2406.03553
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linear layered probabilistic shaping ( llps ) is proposed, an architecture for linear codes to efficiently encode to shaped code words. in the previously proposed probabilistic amplitude shaping ( pas ) architecture, a distribution matcher ( dm ) maps information bits to shaped bits, which are then systematically encoded by appending uniformly distributed parity bits. llps extends pas by probabilistic parity shaping ( pps ), which uses a syndrome dm to calculate shaped parity bits. llps enables the transmission with any desired distribution using linear codes, furthermore, by llps, a given linear code with rate $ r _ \ text { fec } $ can be operated at any rate $ r \ leq r _ \ text { fec } $ by changing the distribution. llps is used with an ldpc code for dirty paper coding against an interfering bpsk signal, improving the energy efficiency by 0. 8 db.
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arxiv:1902.10648
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in recent years several distributed ledger technologies based on directed acyclic graphs ( dags ) have appeared on the market. similar to blockchain technologies, dag - based systems aim to build an immutable ledger and are faced with security concerns regarding the irreversibility of the ledger state. however, due to their more complex nature and recent popularity, the study of adversarial actions has received little attention so far. in this paper we are concerned with a particular type of attack on the iota cryptocurrency, more specifically a parasite chain attack that attempts to revert the history stored in the dag structure, also called the tangle. in order to improve the security of the tangle, we present a detection mechanism for this type of attack. in this mechanism, we embrace the complexity of the dag structure by sampling certain aspects of it, more particularly the distribution of the number of approvers. we initially describe models that predict the distribution that should be expected for a tangle without any malicious actors. we then introduce metrics that compare this reference distribution with the measured distribution. upon detection, measures can then be taken to render the attack unsuccessful. we show that due to a form of the parasite chain that is different from the main tangle it is possible to detect certain types of malicious chains. we also show that although the attacker may change the structure of the parasite chain to avoid detection, this is done so at a significant cost since the attack is rendered less efficient.
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arxiv:2004.13409
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as education systems move toward business models of operation, there is a strong tendency to misidentify the student as the customer. misidentifying the student as the customer leads to interpretation of the course credit or degree as the product. the true product is the additional knowledge, skill, and ability that course credit and degree should represent. consequences are potentially disastrous, because the notion that " the customer is always right " can lead to the perceived product ( course credit or degree ) meeting the desires of the misidentified " customer " ( student ) rather than the real product ( value added to student ) meeting the standards of the properly identified customers ( future employers and taxpayers ).
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arxiv:physics/0612117
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basing on a paper which explores the adoption of a whole system approach to a more sustainable and innovative design, the present paper wants to apply the same approach to a real case, inside of a famous italian sportscar factory. a case study in this factory was developed and decodified gaining improved understanding of whole system design and those factors that substantially influence its success. all the factors mentioned above ( such as dynamics of flattened hierarchy, the need to identify relationship between parts of the system ) are used, into the application presented in this paper, to achieve an ultimate optimization of the whole.
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arxiv:1107.3085
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abridged : to compare the chemistries of stars in the milky way dsph galaxies with stars in the galaxy, we have compiled a large sample of galactic stellar abundances from the literature. as found in previous studies, the [ alpha / fe ] ratios of most stars in the dsph galaxies are generally lower than similar metallicity galactic stars in this extended sample. our kinematically selected stars confirm that this is true for all major stellar components of the galaxy, including the halo, thin disk, and thick disk. there is marginal overlap in the low [ alpha / fe ] ratios between dsph stars and galactic halo stars on extreme retrograde orbits, but this is not supported by other element ratios, like [ ba / y ]. thus, the full chemical signature of most of the dsph stars are distinct from the main components of the galaxy. this result rules out continuous merging of low mass galaxies similar to these dsph satellites during the formation of the galaxy, which is discuss further. the new environments offered by the dsph galaxies also allow us to examine fundamental assumptions related to nucleosynthesis. the metal - poor stars ( [ fe / h ] < - 1. 8 ) in the dsph galaxies have [ alpha / fe ] ratio that are consistent with predictions from the alpha - process ( alpha - rich freeze out ). this may also explain the very low y abundances, and could suggest a separate r - process site for this light ( first peak r - process ) element. in stars with higher metallicities ( [ fe / h ] > - 1. 8 ), contributions from the s - process are expected ; [ ba / y ] is still much higher in the dsph stars than similar metallicity galactic stars though, consistent with s - process contributions from only the low metallicity agb stars in dsph galaxies. finally, the na - ni trend in galactic halo stars is confirmed, but discuss this in terms of nucleosynthesis, and not the accretion of dsphs.
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arxiv:astro-ph/0406120
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we study the search for an extra scalar $ s $ boson produced in association with the $ z $ boson at the international linear collider ( ilc ). the study is performed at center - of - mass energies of 250 gev and 500 gev based on the full simulation of the international large detector ( ild ). in order to be as model - independent as possible, the analysis uses the recoil technique, in particular with the $ z $ boson decaying into a pair of muons. as a result, exclusion cross - section limits are given in terms of a scale factor $ k $ with respect to the standard model higgs - strahlung process cross section. these predicted results, covering all possible searching regions of the extra scalars at the 250 gev ilc and the 500 gev ilc, can be interpreted independently of the decay modes of the $ s $ boson.
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arxiv:1902.06118
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fine - tuning pre - trained generative language models to down - stream language generation tasks has shown promising results. however, this comes with the cost of having a single, large model for each task, which is not ideal in low - memory / power scenarios ( e. g., mobile ). in this paper, we propose an effective way to fine - tune multiple down - stream generation tasks simultaneously using a single, large pre - trained model. the experiments on five diverse language generation tasks show that by just using an additional 2 - 3 % parameters for each task, our model can maintain or even improve the performance of fine - tuning the whole model.
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arxiv:2004.03829
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let $ g $ be a simple graph with $ n $ vertices and $ \ pm 1 $ - weights on edges. suppose that for every edge $ e $ the sum of edges adjacent to $ e $ ( including $ e $ itself ) is positive. then the sum of weights over edges of $ g $ is at least $ - \ frac { n ^ 2 } { 25 } $. also we provide an example of a weighted graph with described properties and the sum of weights $ - ( 1 + o ( 1 ) ) \ frac { n ^ 2 } { 8 ( 1 + \ sqrt { 2 } ) ^ 2 } $. the previous best known bounds were $ - \ frac { n ^ 2 } { 16 } $ and $ - ( 1 + o ( 1 ) ) \ frac { n ^ 2 } { 54 } $ respectively. we show that the constant $ - 1 / 54 $ is optimal under some additional conditions.
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arxiv:2012.09956
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we introduce the new concept of cartesian module over a pseudofunctor $ r $ from a small category to the category of small preadditive categories. already the case when $ r $ is a ( strict ) functor taking values in the category of commutative rings is sufficient to cover the classical construction of quasi - coherent sheaves of modules over a scheme. on the other hand, our general setting allows for a good theory of contravariant additive locally flat functors, providing a geometrically meaningful extension of crawley - boevey ' s representation theorem. as an application, we relate and extend some previous constructions of the pure derived category of a scheme.
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arxiv:1505.07086
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in this work we introduce a new combinatorial notion of boundary $ \ re c $ of an $ \ omega $ - dimensional cubing $ c $. $ \ re c $ is defined to be the set of almost - equality classes of ultrafilters on the standard system of halfspaces of $ c $, endowed with an order relation reflecting the interaction between the tychonoff closures of the classes. when $ c $ arises as the dual of a cubulation - - or discrete system of halfspaces - - $ \ hh $ of a cat ( 0 ) space $ x $ ( for example, the niblo - reeves cubulation of the davis - moussong complex of a finite rank coxeter group ), we show how $ \ hh $ induces a function $ \ rho : \ bd x \ to \ re c $. we develop a notion of uniformness for $ \ hh $, generalizing the parallel walls property enjoyed by coxeter groups, and show that, if the pair $ ( x, \ hh ) $ admits a geometric action by a group $ g $, then the fibers of $ \ rho $ form a stratification of $ \ bd x $ graded by the order structure of $ \ re c $. we also show how this structure computes the components of the tits boundary of $ x $. finally, using our result from another paper, that the uniformness of a cubulation as above implies the local finiteness of $ c $, we give a condition for the co - compactness of the action of $ g $ on $ c $ in terms of $ \ rho $, generalizing a result of williams, previously known only for coxeter groups.
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arxiv:math/0611006
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the galactic bulge shows a double red clump in sight lines with | b | > 5 deg and - 3 deg < l < 4 deg. it is interpreted as a signature of an x - shaped structure seen almost edge - on. we measure the proper motions of the stars belonging to the closer and the further arm of the x - shaped structure. the intrinsic kinematic properties of the two arms are found by incorporating information taken from the luminosity function. at b = - 5 deg we find that the proper motion difference between the two arms is a linear function of the galactic longitude for - 0. 1 deg < l < 0. 5 deg, which we interpret as a streaming motion of the stars within the x - shaped structure. such a streaming motion has not previously been reported. the proper motion difference is constant for - 0. 8 deg < l < - 0. 1 deg, which gives us an estimate of bulge rotation speed of 87. 9 + / - 8. 2 km / s / kpc.
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arxiv:1304.6084
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we study the decay of a standard model - like higgs boson into a gravitino and a neutralino, which subsequently decays promptly into another gravitino and a photon. such a decay can be important in scenarios where the supersymmetry breaking scale is of the order of a few tev, and in the region of low transverse momenta of the photon, it may provide the dominant contribution to the final state with a photon and two gravitinos. we estimate the relevant standard model backgrounds and the prospects for discovering this higgs decay through a photon and missing transverse energy signal at the lhc in terms of a simplified model. we also give an explicit model with manifest, but spontaneously broken, supersymmetry in which the usual mssm soft terms are promoted to supersymmetric operators involving a dynamical goldstino supermultiplet. this model can give rise to a sm - like cp - even neutral higgs particle with a mass of 125 gev, without requiring substantial radiative corrections, and with couplings sufficiently large for a signal discovery through the above mentioned higgs decay channel with the upcoming data from the lhc.
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arxiv:1203.4563
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the main part of this contribution to the special issue of ejm - b / fluids dedicated to patrick huerre outlines the problem of the subcritical transition to turbulence in wall - bounded flows in its historical perspective with emphasis on plane couette flow, the flow generated between counter - translating parallel planes. subcritical here means discontinuous and direct, with strong hysteresis. this is due to the existence of nontrivial flow regimes between the global stability threshold re _ g, the upper bound for unconditional return to the base flow, and the linear instability threshold re _ c characterized by unconditional departure from the base flow. the transitional range around re _ g is first discussed from an empirical viewpoint ( { \ s } 1 ). the recent determination of re _ g for pipe flow by avila et al. ( 2011 ) is recalled. plane couette flow is next examined. in laboratory conditions, its transitional range displays an oblique pattern made of alternately laminar and turbulent bands, up to a third threshold re _ t beyond which turbulence is uniform. our current theoretical understanding of the problem is next reviewed ( { \ s } 2 ) : linear theory and non - normal amplification of perturbations ; nonlinear approaches and dynamical systems, basin boundaries and chaotic transients in minimal flow units ; spatiotemporal chaos in extended systems and the use of concepts from statistical physics, spatiotemporal intermittency and directed percolation, large deviations and extreme values. two appendices present some recent personal results obtained in plane couette flow about patterning from numerical simulations and modeling attempts.
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arxiv:1403.6374
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a theoretical quantum teleportation protocal is suggested to teleport accelerated and non - accelerated information over different classes of accelerated quantum channels. for the accelerated information, it is shown that the fidelity of the teleported state increases as the entanglement of the initial quantum channel increases. however as the difference between the accelerated channel and the accelerated information decreases the fidelity increases. the fidelity of the non accelerated information increases as the entanglement of the initial quantum channel increases, while the accelerations of the quantum channel has a little effect. the possibility of sending quantum information over accelerated quantum channels is much better than sending classical information.
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arxiv:1206.3784
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we investigate the interpolation of power spectra of matter fluctuations using artificial neural network ( pkann ). we present a new approach to confront small - scale non - linearities in the power spectrum of matter fluctuations. this ever - present and pernicious uncertainty is often the achilles ' heel in cosmological studies and must be reduced if we are to see the advent of precision cosmology in the late - time universe. we show that an optimally trained artificial neural network ( ann ), when presented with a set of cosmological parameters ( omega _ m h ^ 2, omega _ b h ^ 2, n _ s, w _ 0, sigma _ 8, m _ nu and redshift z ), can provide a worst - case error < = 1 per cent ( for z < = 2 ) fit to the non - linear matter power spectrum deduced through n - body simulations, for modes up to k < = 0. 7 h / mpc. our power spectrum interpolator is accurate over the entire parameter space. this is a significant improvement over some of the current matter power spectrum calculators. in this paper, we detail how an accurate interpolation of the matter power spectrum is achievable with only a sparsely sampled grid of cosmological parameters. unlike large - scale n - body simulations which are computationally expensive and / or infeasible, a well - trained ann can be an extremely quick and reliable tool in interpreting cosmological observations and parameter estimation. this paper is the first in a series. in this method paper, we generate the non - linear matter power spectra using halofit and use them as mock observations to train the ann. this work sets the foundation for paper ii, where a suite of n - body simulations will be used to compute the non - linear matter power spectra at sub - per cent accuracy, in the quasi - non - linear regime 0. 1 h / mpc < = k < = 0. 9 h / mpc. a trained ann based on this n - body suite will be released for the scientific community.
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arxiv:1203.1695
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in this paper we prove the homotopy lifting property for actions of finite abelian groups on hausdorff topological spaces.
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arxiv:2003.01195
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online continual learning ( cl ) solves the problem of learning the ever - emerging new classification tasks from a continuous data stream. unlike its offline counterpart, in online cl, the training data can only be seen once. most existing online cl research regards catastrophic forgetting ( i. e., model stability ) as almost the only challenge. in this paper, we argue that the model ' s capability to acquire new knowledge ( i. e., model plasticity ) is another challenge in online cl. while replay - based strategies have been shown to be effective in alleviating catastrophic forgetting, there is a notable gap in research attention toward improving model plasticity. to this end, we propose collaborative continual learning ( ccl ), a collaborative learning based strategy to improve the model ' s capability in acquiring new concepts. additionally, we introduce distillation chain ( dc ), a collaborative learning scheme to boost the training of the models. we adapt ccl - dc to existing representative online cl works. extensive experiments demonstrate that even if the learners are well - trained with state - of - the - art online cl methods, our strategy can still improve model plasticity dramatically, and thereby improve the overall performance by a large margin. the source code of our work is available at https : / / github. com / maorong - wang / ccl - dc.
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arxiv:2312.00600
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star - forming galaxies in the early universe provide us with perhaps the most natural way of explaining the reionization of the universe. current observational results are sufficiently comprehensive, as to allow us to approximately calculate how the ionizing radiation from galaxies varies as a function of cosmic time. important uncertainties in modeling reionization by galaxies revolve around the escape fraction and its luminosity and redshift dependence, a possible truncation of the galaxy luminosity function at the faint end, and an evolution in the production efficiency of lyman - continuum photons with cosmic time. despite these uncertainties, plausible choices for these parameters naturally predict a cosmic ionizing emissivity at z ~ 6 - 10 whose evolution and overall normalization is in excellent agreement with that derived from current observational constraints. this strongly suggests that galaxies provide the necessary photons to reionize the universe.
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arxiv:1511.01133
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