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we present and compare projected distributions of mass, galaxies, and the intracluster medium ( icm ) for a sample of merging clusters of galaxies based on the joint weak - lensing, optical photometric, and x - ray analysis. our sample comprises seven nearby abell clusters, for which we have conducted systematic, deep imaging observations with suprime - cam on subaru telescope. our seven target clusters, representing various merging stages and conditions, allow us to investigate in details the physical interplay between dark matter, icm, and galaxies associated with cluster formation and evolution. a1750 and a1758 are binary systems consisting of two cluster - sized components, a520, a754, a1758n, a1758s, and a1914 are on - going cluster mergers, and a2034 and a2142 are cold - front clusters. in the binary clusters, the projected mass, optical light, and x - ray distributions are overall similar and regular without significant substructures. on - going and cold - front merging clusters, on the other hand, reveal highly irregular mass distributions. overall the mass distribution appears to be similar to the galaxy luminosity distribution, whereas their distributions are quite different from the icm distribution in a various ways. we also measured for individual targets the global cluster parameters such as the cluster mass, the mass - to - light ratio, and the icm temperature. a comparison of the icm and virial temperatures of merging clusters from x - ray and weak - lensing analyses, respectively, shows that the icm temperature of on - going and cold - front clusters is significantly higher than the cluster virial temperature by a factor of $ \ sim 2 $. this temperature excess in the icm could be explained by the effects of merger boosts. | arxiv:astro-ph/0702649 |
we consider complex fermi curves of electric and magnetic periodic fields. these are analytic curves in c ^ 2 that arise from the study of the eigenvalue problem for periodic schroedinger operators. we characterize a certain class of these curves in the region of c ^ 2 where at least one of the coordinates has " large " imaginary part. the new results in this work extend previous results in the absence of magnetic field to the case of " small " magnetic field. our theorems can be used to show that generically these fermi curves belong to a class of riemann surfaces of infinite genus. | arxiv:1003.0586 |
we discuss dark energy models which might describe effectively the actual acceleration of the universe. more precisely, for a 4 - dimensional friedmann - lema \ ^ { \ i } tre - robertson - walker ( flrw ) universe we consider two situations : first of them, we model dark energy by phantom energy described by a perfect fluid satisfying the equation of state $ p = ( \ beta - 1 ) \ rho $ ( with $ \ beta < 0 $ and constant ). in this case the universe reaches a ` ` big rip ' ' independently of the spatial geometry of the flrw universe. in the second situation, the dark energy is described by a phantom ( generalized ) chaplygin gas which violates the dominant energy condition. contrary to the previous case, for this material content a flrw universe would never reach a ` ` big rip ' ' singularity ( indeed, the geometry is asymptotically de sitter ). we also show how this dark energy model can be described in terms of scalar fields, corresponding to a minimally coupled scalar field, a born - infeld scalar field and a generalized born - infeld scalar field. finally, we introduce a phenomenologically viable model where dark energy is described by a phantom generalized chaplygin gas. | arxiv:astro-ph/0404540 |
we generalize in positive characteristics some results of bien and brion on log homogeneous compactifications of a homogeneous space under the action of a connected reductive group. we also construct an explicit smooth log homogeneous compactification of the general linear group by successive blow - ups starting from a grassmannian. by taking fixed points of certain involutions on this compactification, we obtain smooth log homogeneous compactifications of the special orthogonal and the symplectic groups. | arxiv:1403.4337 |
we employ a high - resolution dissipationless n - body simulation of a galaxy cluster to investigate the impact of subhalo selection on the resulting velocity distributions. applying a lower limit on the present bound mass of subhalos leads to high subhalo velocity dispersions compared to the diffuse dark matter ( positive velocity bias ) and to a considerable deviation from a gaussian velocity distribution ( kurtosis - 0. 6 ). however, if subhalos are required to exceed a minimal mass before accretion onto the host, the velocity bias becomes negligible and the velocity distribution is close to gaussian ( kurtosis - 0. 15 ). recently it has been shown that the latter criterion results in subhalo samples that agree well with the observed number - density profiles of galaxies in clusters. therefore we argue that the velocity distributions of galaxies in clusters are essentially un - biased. the comparison of the galaxy velocity distribution and the sound speed, derived from scaling relations of x - ray observations, results in an average mach number of 1. 24. altogether 65 % of the galaxies move supersonically and 8 % have mach numbers larger than 2 with respect to the intra cluster gas. | arxiv:astro-ph/0602197 |
the next generation of long baseline neutrino experiments will aim at determining the value of the unknown mixing angle, theta _ { 13 }, the type of neutrino mass hierarchy and the presence of cp - violation in the lepton sector. beta - beams and electron capture experiments have been studied as viable candidates for long baseline experiments. they use a very clean electron neutrino beam from the beta - decays or electron capture decays of boosted ions. in the present article we consider an hybrid setup which combines a beta - beam with an electron capture beam by using boosted ytterbium ions. we study the sensitivity to the cp - violating phase delta and the theta _ { 13 } angle, the cp - discovery potential and the reach to determine the type of neutrino mass hierarchy for this type of long baseline experiment. the analysis is performed for different neutrino beam energies and baselines. finally, we also discuss how the results would change if a better knowledge of some of the assumed parameters was achieved by the time this experiment could take place. | arxiv:0902.4903 |
in 1984, ' t hooft famously used a brickwall ( aka stretched horizon ) to compute black hole entropy up to a numerical pre - factor. this calculation is sometimes interpreted as due to the entanglement of the modes across the horizon, but more operationally, it is simply an indirect count of the semi - classical modes trapped between the stretched horizon and the angular momentum barrier. because the calculation was indirect, it needed both the mass and the temperature of the black hole as inputs, to reproduce the area. a more conventional statistical mechanics calculation should be able to get the entropy, once the ensemble is specified ( say via the energy, in a microcanonical setting ). in this paper, we explicitly compute black hole normal modes in various examples, numerically as well as ( in various regimes ) analytically. the explicit knowledge of normal modes allows us to reproduce $ both $ the hawking temperature as well as the entropy, once the charges are specified, making this a conventional statistical mechanics calculation. a quasi - degeneracy in the angular quantum numbers is directly responsible for the area scaling of the entropy, and is the key distinction between the planckian black body calculation ( volume scaling ) and the ' t hooftian calculation ( area scaling ). we discuss the ( rotating ) btz case in detail and match the thermodynamic quantities $ exactly $. schwarzschild and kerr normal modes are discussed in less detail using near - horizon approximations. our calculations reveal a new hierarchy in the angular quantum numbers, which we speculate is related to string theory. | arxiv:2312.14109 |
hess j0632 + 057 is a gamma - ray binary composed of a compact object and a be star, with an orbital period of about 315 days. the actual nature of its non - thermal emission, spanning from radio to very - high - energy ( vhe, > 100 gev ) gamma - rays, is currently unknown. in this contribution we will present the results of a set of simultaneous observations performed by the nustar x - ray telescope and the veritas observatory. the combination of hard x - rays ( 3 - 30 kev ) and vhe gamma - rays ( 0. 1 - 5 tev ) provide valuable information for the understanding of the radiative processes occurring in the system. the spectral energy distributions ( sed ) derived from the observations are used to probe the pulsar scenario, in which the system is powered by a rapidly rotating neutron star. the non - thermal emission is produced by the particles accelerated at the shock formed by the collision of the pulsar and stellar winds. as a results of the model fitting, we constrain the relation between the pulsar spin - down luminosity and the magnetization of the pulsar wind. | arxiv:1908.03083 |
in a privacy - focused era, federated learning ( fl ) has emerged as a promising machine learning technique. however, most existing fl studies assume that the data distribution remains nearly fixed over time, while real - world scenarios often involve dynamic and continual changes. to equip fl systems with continual model evolution capabilities, we focus on an important problem called federated continual novel class learning ( fedcn ) in this work. the biggest challenge in fedcn is to merge and align novel classes that are discovered and learned by different clients without compromising privacy. to address this, we propose a global alignment learning ( gal ) framework that can accurately estimate the global novel class number and provide effective guidance for local training from a global perspective, all while maintaining privacy protection. specifically, gal first locates high - density regions in the representation space through a bi - level clustering mechanism to estimate the novel class number, with which the global prototypes corresponding to novel classes can be constructed. then, gal uses a novel semantic weighted loss to capture all possible correlations between these prototypes and the training data for mitigating the impact of pseudo - label noise and data heterogeneity. extensive experiments on various datasets demonstrate gal ' s superior performance over state - of - the - art novel class discovery methods. in particular, gal achieves significant improvements in novel - class performance, increasing the accuracy by 5. 1 % to 10. 6 % in the case of one novel class learning stage and by 7. 8 % to 17. 9 % in the case of two novel class learning stages, without sacrificing known - class performance. moreover, gal is shown to be effective in equipping a variety of different mainstream fl algorithms with novel class discovery and learning capability, highlighting its potential for many real - world applications. | arxiv:2312.13500 |
colonoscopy plays a crucial role in the diagnosis and prognosis of various gastrointestinal diseases. due to the challenges of collecting large - scale high - quality ground truth annotations for colonoscopy images, and more generally medical images, we explore using self - supervised features from vision transformers in three challenging tasks for colonoscopy images. our results indicate that image - level features learned from dino models achieve image classification performance comparable to fully supervised models, and patch - level features contain rich semantic information for object detection. furthermore, we demonstrate that self - supervised features combined with unsupervised segmentation can be used to discover multiple clinically relevant structures in a fully unsupervised manner, demonstrating the tremendous potential of applying these methods in medical image analysis. | arxiv:2312.12599 |
the old chinese puzzle tangram gives rise to serious mathematical problems when one asks for all tangram figures that satisfy particular geometric properties. all $ 13 $ convex tangram figures are known since 1942. they include the only triangular and all six quadrangular tangram figures. the families of all $ n $ - gonal tangram figures with $ n \ ge 6 $ are either infinite or empty. here we characterize all $ 53 $ pentagonal tangram figures, including $ 51 $ non - convex pentagons and $ 31 $ pentagons whose vertices are not contained in the same orthogonal lattice. | arxiv:2006.09698 |
in this note we provide a simple explanation of the recent finding of anisotropy in electromagnetic ( em ) propagation claimed by nodland and ralston ( astro - ph / 9704196 ). we consider, as a possible origin of such effect, the effective coupling between em fields and some tiny background torsion field. the coupling is obtained after integrating out charged fermions, it is gauge invariant and does not require the introduction of any new physics. | arxiv:astro-ph/9706044 |
information geometric causal inference ( igci ) is a new approach to distinguish between cause and effect for two variables. it is based on an independence assumption between input distribution and causal mechanism that can be phrased in terms of orthogonality in information space. we describe two intuitive reinterpretations of this approach that makes igci more accessible to a broader audience. moreover, we show that the described independence is related to the hypothesis that unsupervised learning and semi - supervised learning only works for predicting the cause from the effect and not vice versa. | arxiv:1402.2499 |
paralleling a previous paper, we examine single - and many - body states of relativistic electrons in an intense, rotating magnetic dipole field. single - body orbitals are derived semiclassically and then applied to the many - body case via the thomas - fermi approximation. the many - body case is reminiscent of the quantum hall state. electrons in a realistic neutron star crust are considered with both fixed density profiles and constant fermi energy. in the first case, applicable to young neutron star crusts, the varying magnetic field and relativistic coriolis correction lead to a varying fermi energy and macroscopic currents. in the second, relevant to older crusts, the electron density is redistributed by the magnetic field. | arxiv:astro-ph/9707196 |
sound field reproduction methods based on numerical optimization, which aim to minimize the error between synthesized and desired sound fields, are useful in many practical scenarios because of their flexibility in the array geometry of loudspeakers. however, the reproduction performance of these methods in a practical environment has not been sufficiently investigated. we evaluate weighted mode matching, which is a sound field reproduction method based on the spherical wavefunction expansion of the sound field, in comparison with conventional pressure matching. we also introduce a method of infinite - dimensional harmonic analysis for estimating the expansion coefficients of the sound field from microphone measurements. experimental results indicated that weighted mode matching using the expansion coefficients of the transfer functions estimated by the infinite - dimensional harmonic analysis outperforms conventional pressure matching, especially when the number of microphones is small. | arxiv:2111.11045 |
we consider simple loopless finite undirected graphs. such a graph is called strongly regular with parameter set ( v, k, l, m ), for short a srg ( v, k, l, m ), iff it has exactly v vertices, each of them has exactly k neighbours, and the number of common neighbours of any two different vertices is l if they are neighbours and m otherwise. the g2 ( 4 ) graph is a well - known srg ( 416, 100, 36, 20 ). in this article, we explicitly construct it and a certain subgraph e induced by 320 vertices in the same way as in an older article by this author. we discover some interesting properties of e and derive five strongly regular graphs from it : a srg ( 256, 60, 20, 12 ) f which is a subgraph induced by 256 vertices and four srg ( 336, 80, 28, 16 ) h, h _ 1, h _ 2 and h _ 3 which do have e as induced subgraph. the latter three graphs are new in version 4 of this article and seem to have been completely unknown as h was before version 1 appeared. the graph f is isomorphic to objects described as unions of 16 16 - cocliques in a description of subgraphs of the g2 ( 4 ) graph by andries e. brouwer ; but the strong regularity has been unnoticed before version 1 of this article. several propositions in this article have been checked by executing the additionally ( in the source package ) provided program g24dgs2 and the program dreadnaut from the popular graph theoretic software nauty ( by brendan mckay and adolfo piperno ). | arxiv:1409.3520 |
we evaluate the impact of one - loop electroweak corrections to the spin - independent dark matter ( dm ) scattering cross - section with nucleons ( $ \ sigma _ { \ rm si } $ ), in models with a so - called blind spot for direct detection, where the leading - order prediction for the relevant dm coupling to the higgs boson, and therefore $ \ sigma _ { \ rm si } $, are vanishingly small. adopting a simple illustrative scenario in which the dm state results from the mixing of electroweak singlet and doublet fermions, we compute the relevant higher order corrections to the scalar effective operator contributions to $ \ sigma _ { \ rm si } $, stemming from both triangle and box diagrams involving the sm and dark sector fields. it is observed that in a significant region of the singlet - doublet model - space, the one - loop corrections ` ` unblind ' ' the tree - level blind spots and lead to detectable si scattering rates at future multi - ton scale liquid xenon experiments, with $ \ sigma _ { \ rm si } $ reaching values up to a few times $ 10 ^ { - 47 } { ~ \ rm cm } ^ 2 $, for a weak scale dm with $ \ mathcal { o } ( 1 ) $ yukawa couplings. furthermore, we find that there always exists a new si blind spot at the next - to - leading order, which is perturbatively shifted from the leading order one in the singlet - doublet mass parameters. for comparison, we also present the tree - level spin - dependent scattering cross - sections near the si blind - spot region, that could lead to a larger signal. our results can be mapped to the blind - spot scenario for bino - higgsino dm in the mssm, with other sfermions, the heavier higgs boson, and the wino decoupled. | arxiv:1810.04679 |
fog computing allows applications to address their latency and privacy requirements while coping with bandwidth limitations of internet service providers ( isps ). existing research on fog systems has so far mostly taken a very high - level view on the actual fog infrastructure. in this position paper, we identify and discuss the problem of having multiple isps in edge - to - edge communication. as a possible solution we propose that edge operators create direct edge - to - edge links in a grassroots fashion and discuss different implementation options. based on this, we highlight some important open research challenges that result from this. | arxiv:2201.03462 |
we aim at giving a rigorous proof of the state - ments on the smoothness and the dimension of severi varieties wherethere are gaps in the proofs in some standard literature. the method isa mixture of algebraic and analytic methods. | arxiv:1912.05089 |
we present a multi - wavelength ( x - ray, $ \ gamma $ - ray, optical and radio ) study of hd 194816, a late o - type x - ray detected spectroscopic binary. x - ray spectra are analyzed and the x - ray photon arrival times are checked for pulsation. in addition, newly obtained optical spectroscopic monitoring data on hd 164816 are presented. they are complemented by available radio data from several large scale surveys as well as the \ emph { fermi } $ \ gamma $ - ray data from its \ emph { large area telescope }. we report the detection of a low energy excess in the x - ray spectrum that can be described by a simple absorbed blackbody model with a temperature of $ \ sim $ 50 ev as well as a 9. 78 s pulsation of the x - ray source. the soft x - ray excess, the x - ray pulsation, and the kinematical age would all be consistent with a compact object like a neutron star as companion to hd 164816. the size of the soft x - ray excess emitting area is consistent with a circular region with a radius of about 7 km, typical for neutron stars, while the emission measure of the remaining harder emission is typical for late o - type single or binary stars. if hd 164816 includes a neutron star born in a supernova, this supernova should have been very recent and should have given the system a kick, which is consistent with the observation that the star hd 164816 has a significantly different radial velocity than the cluster mean. in addition we confirm the binarity of hd 164816 itself by obtaining an orbital period of 3. 82 d, projected masses $ m _ 1 { \ rm sin } ^ { 3 } i $ = 2. 355 ( 69 ) m $ _ \ odot $, $ m _ 2 { \ rm sin } ^ { 3 } i $ = 2. 103 ( 62 ) m $ _ \ odot $ apparently seen at low inclination angle, determined from high - resolution optical spectra. | arxiv:1209.2592 |
we introduce immanant varieties, associated to simple characters of a finite group. they include well - studied classes of varieties, as segre embeddings, grassmannians and certain other classes of chow varieties. for a one - dimensional character $ \ chi $, we define $ \ chi $ - matroids by a maximality property. for trivial characters, by exploring the combinatorics of incidence stratifications, we provide a set of generators for the chow vector spaces of the corresponding immanant varieties. | arxiv:2211.11634 |
in a recent comment on the paper " dark matter as a weyl geometric effect ", by burikham et al., phys. rev. d 107, 064008 ( 2023 ), posted on arxiv. org as eprint arxiv : 2306. 11926, it was claimed that the exact solution found in the above mentioned paper by burikham et al. " is wrong ". in this reply to the comment we present, in a clear and comprehensive way, a step by step derivation of the exact solution of the vacuum static spherically symmetric field equations of the weyl geometric gravity theory, and we show that, contrary to the claims in arxiv : 2306. 11926, the obtained solution is correct, and it satisfies all the equations of motion of the basic theory. hence, it can be considered as a viable alternative model for the explanation of the behavior of the galactic rotation curves, without invoking the presence of dark matter. | arxiv:2310.13423 |
a scenario is presented, based on renormalization group ( linear perturbation ) ideas, which can explain the self - similarity and scaling observed in a numerical study of gravitational collapse of radiation fluid. in particular, it is shown that the critical exponent $ \ beta $ and the largest lyapunov exponent $ { \ rm re \, } \ kappa $ of the perturbation is related by $ \ beta = ( { \ rm re \, } \ kappa ) ^ { - 1 } $. we find the relevant perturbation mode numerically, and obtain a fairly accurate value of the critical exponent $ \ beta \ simeq 0. 3558019 $, also in agreement with that obtained in numerical simulation. | arxiv:gr-qc/9503007 |
we present a detection scheme which using imperfect detectors, and imperfect quantum copying machines ( which entangle the copies ), allows one to extract more information from an incoming signal, than with the imperfect detectors alone. | arxiv:quant-ph/9911103 |
in this proceedings contribution, i briefly summarize various aspects that are important in the discussions of new physics searches with novel scalar states, at current and future colliders. in particular, i give a brief glance on the status of two higgs doublet models, and discuss multi - scalar production as well as interference effects in di - higgs searches. i also mention searches of new scalar final states at possible higgs factories. | arxiv:2504.13014 |
the thermoelectric thomson effect, predicted in the 1850s by william thomson, produces volumetric heating / cooling in a conductor due to the concerted action of the seebeck and peltier effects. recently, transverse thermoelectrics studies on the nernst and ettingshausen effects have progressed rapidly to enable versatile thermal management technologies and to explore topological transport properties. however, a transverse thomson effect, arising from the concerted action of the nernst and ettingshausen effects, has not yet been observed. here, we report the observation of the transverse thomson effect in a conductor. we observed volumetric heating / cooling in a semimetallic bi $ _ { 88 } $ sb $ _ { 12 } $ alloy induced by a charge current, temperature gradient, and magnetic field applied orthogonally to each other using thermoelectric imaging techniques. we found that the heating / cooling can be switched by the field direction. our experiments and analyses reveal the essential difference between the conventional and transverse thomson effects ; the former depends sorely on the temperature derivative of the seebeck coefficient, while the latter depends not only on the temperature derivative of the nernst coefficient but also on its magnitude. the observation of the transverse thomson effect fills a missing piece in the history of thermoelectrics and provides a new principle for active thermal management technologies. | arxiv:2501.05857 |
thus, field extensions can be split into ones of the form e ( s ) / e ( purely transcendental extensions ) and algebraic extensions. = = = closure operations = = = a field is algebraically closed if it does not have any strictly bigger algebraic extensions or, equivalently, if any polynomial equation fn xn + fn−1xn−1 + + f1x + f0 = 0, with coefficients fn,..., f0 ∈ f, n > 0, has a solution x f. by the fundamental theorem of algebra, c is algebraically closed, i. e., any polynomial equation with complex coefficients has a complex solution. the rational and the real numbers are not algebraically closed since the equation x2 + 1 = 0 does not have any rational or real solution. a field containing f is called an algebraic closure of f if it is algebraic over f ( roughly speaking, not too big compared to f ) and is algebraically closed ( big enough to contain solutions of all polynomial equations ). by the above, c is an algebraic closure of r. the situation that the algebraic closure is a finite extension of the field f is quite special : by the artin – schreier theorem, the degree of this extension is necessarily 2, and f is elementarily equivalent to r. such fields are also known as real closed fields. any field f has an algebraic closure, which is moreover unique up to ( non - unique ) isomorphism. it is commonly referred to as the algebraic closure and denoted f. for example, the algebraic closure q of q is called the field of algebraic numbers. the field f is usually rather implicit since its construction requires the ultrafilter lemma, a set - theoretic axiom that is weaker than the axiom of choice. in this regard, the algebraic closure of fq, is exceptionally simple. it is the union of the finite fields containing fq ( the ones of order qn ). for any algebraically closed field f of characteristic 0, the algebraic closure of the field f ( ( t ) ) of laurent series is the field of puiseux series, obtained by adjoining roots of t. = = fields with additional structure = = since fields are ubiquitous in mathematics and beyond, several refinements of the concept have been adapted to the needs of particular mathematical areas. = = = ordered fields = = = a field f is called an ordered field if any two elements can be compared, so that x + y ≥ 0 | https://en.wikipedia.org/wiki/Field_(mathematics) |
we present near - infrared spectroscopy of the sporadically active asteroid ( 6478 ) gault collected on the 3 m nasa / infrared telescope facility observatory in late 2019 march / early april. long - exposure imaging with the 0. 5 m neemo t05 telescope and previously published data simultaneously monitored the asteroid activity, providing context for our measurements. we confirm gault is a silicate - rich ( q - or s - type ) object likely linked to the ( 25 ) phocaea collisional family. the asteroid exhibits substantial spectral variability over the 0. 75 - 2. 45 $ \ mu $ m wavelength range, from unusual blue ( s ' = - 13. 5 + / - 1. 1 % $ \ mu $ m - 1 to typical red ( s ' = + 9. 1 + / - 1. 2 % $ \ mu $ m - 1 ) spectral slope, that does not seem to correlate with activity. spectral comparisons with samples of ordinary chondrite meteorites suggest that the blue color relates to the partial loss of the asteroid dust regolith, exposing a fresh, dust - free material at its surface. the existence of asteroids rotating close to rotational break - up limit and having similar spectral properties as gault further supports this interpretation. future spectroscopic observations of gault, when the tails dissipate, will help further testing of our proposed hypothesis. | arxiv:1907.10077 |
a tight correlation between the radio and x - ray emission in the hard state of black hole x - ray binaries ( bhxrbs ) indicates an intrinsic disc - jet connection in stellar black hole accretion systems, though the detailed physics processes at work are still quite unclear. a hot accretion flow is suggested to match the outer cold thin disc at a certain radius in the hard state, which may vary with the accretion rate. in this work, we assume that the magnetic field generated in the outer thin disc is advected inwards by the inner hot accretion flow, which is substantially enhanced near the bh. such a strong field threading the horizon of a spinning bh is responsible for launching relativistic jets in bhxrbs via the blandford - znajek mechanism. thus, both the jet power and the x - ray emission increase with the mass accretion rate, and we find that our model calculations are able to reproduce the observed radio / x - ray correlation quantitatively. for some individual bhxrbs, the slopes of the radio / x - ray correlations become steeper when the sources are brighter. our model calculations show that this feature is due to the transition of the outer disc with gas pressure dominated to radiation pressure dominated, which leads to different accretion rate dependence of the field strength in the outer disc. | arxiv:2407.14856 |
the paper erroneously assumed that the normal carriers giving rise to the backflow could be either electrons or holes. | arxiv:1609.06299 |
in the cores of some galaxy clusters the hot intracluster plasma is dense enough that it should cool radiatively in the cluster ' s lifetime, leading to continuous " cooling flows " of gas sinking towards the cluster center, yet no such cooling flow has been observed. the low observed star formation rates and cool gas masses for these " cool core " clusters suggest that much of the cooling must be offset by astrophysical feedback to prevent the formation of a runaway cooling flow. here we report x - ray, optical, and infrared observations of the galaxy cluster spt - clj2344 - 4243 at z = 0. 596. these observations reveal an exceptionally luminous ( l _ 2 - 10 kev = 8. 2 x 10 ^ 45 erg / s ) galaxy cluster which hosts an extremely strong cooling flow ( dm / dt = 3820 + / - 530 msun / yr ). further, the central galaxy in this cluster appears to be experiencing a massive starburst ( 740 + / - 160 msun / yr ), which suggests that the feedback source responsible for preventing runaway cooling in nearby cool core clusters may not yet be fully established in spt - clj2344 - 4243. this large star formation rate implies that a significant fraction of the stars in the central galaxy of this cluster may form via accretion of the intracluster medium, rather than the current picture of central galaxies assembling entirely via mergers. | arxiv:1208.2962 |
the group is interesting as the first example of split rank 2 semisimple group, all the irreducible unitary representations of which are known. we make a precise realization of the discrete series representations ( in section 2 ) by using the orbit method and geometric quantization, a computation of their traces ( section 3 ) and an exact formula for the noncommutative poisson summation and endoscopy of for this group ( in section 4 ). | arxiv:1407.6912 |
we present the main features in the evolution of the gas pressure in star forming regions, from the formation of the parental cloud to the moment when the region is pressurized by interacting stellar winds. the main processes for cloud destruction and the self - limiting properties of star formation are described. the high star forming efficiency in nuclear starbursts is a consequence of the high gas pressures. the evolution of slow winds in highly pressurized region is also sketched. | arxiv:astro-ph/9609054 |
this paper gives a complete primary decomposition of the first, that is, the smallest, mayr - meyer ideal, its radical, and the intersection of its minimal components. the particular membership problem which makes the mayr - meyer ideals ' complexity doubly exponential in the number of variables is here examined also for the radical and the intersection of the minimal components. it is proved that for the first mayr - meyer ideal the complexity of this membership problem is the same as for its radical. this problem was motivated by a question of bayer, huneke and stillman. | arxiv:math/0209154 |
randomising networks using a naive ` accept - all ' edge - swap algorithm is generally biased. building on recent results for nondirected graphs, we construct an ergodic detailed balance markov chain with non - trivial acceptance probabilities for directed graphs, which converges to a strictly uniform measure and is based on edge swaps that conserve all in - and out - degrees. the acceptance probabilities can also be generalized to define markov chains that target any alternative desired measure on the space of directed graphs, in order to generate graphs with more sophisticated topological features. this is demonstrated by defining a process tailored to the production of directed graphs with specified degree - degree correlation functions. the theory is implemented numerically and tested on synthetic and biological network examples. | arxiv:1112.4677 |
we consider a dirichlet problem for the poisson equation in a periodically perforated domain. the geometry of the domain is controlled by two parameters : a real number $ \ epsilon > 0 $ proportional to the radius of the holes and a map $ \ phi $, which models the shape of the holes. so, if $ g $ denotes the dirichlet boundary datum and $ f $ the poisson datum, we have a solution for each quadruple $ ( \ epsilon, \ phi, g, f ) $. our aim is to study how the solution depends on $ ( \ epsilon, \ phi, g, f ) $, especially when $ \ epsilon $ is very small and the holes narrow to points. in contrast with previous works, we don ' t introduce the assumption that $ f $ has zero integral on the fundamental periodicity cell. this brings in a certain singular behavior for $ \ epsilon $ close to $ 0 $. we show that, when the dimension $ n $ of the ambient space is greater than or equal to $ 3 $, a suitable restriction of the solution can be represented with an analytic map of the quadruple $ ( \ epsilon, \ phi, g, f ) $ multiplied by the factor $ 1 / \ epsilon ^ { n - 2 } $. in case of dimension $ n = 2 $, we have to add $ \ log \ epsilon $ times the integral of $ f / 2 \ pi $. | arxiv:2211.11631 |
we study the colored resonance production at the lhc in a most general approach. we classify the possible colored resonances based on group theory decomposition, and construct their effective interactions with light partons. the production cross section from annihilation of valence quarks or gluons may be on the order of 400 - 1000 pb at lhc energies for a mass of 1 tev with nominal couplings, leading to the largest production rates for new physics at the tev scale, and simplest event topology with dijet final states. we apply the new dijet data from the lhc experiments to put bounds on various possible colored resonant states. the current bounds range from 0. 9 to 2. 7 tev. the formulation is readily applicable for future searches including other decay modes. | arxiv:1010.4309 |
we present the possibility of spin - dependent kapitza - dirac scattering based on a two - photon interaction only. the interaction scheme is inspired from a compton scattering process, for which we explicitly show the mathematical correspondence to the spin - dynamics of an electron diffraction process in a standing light wave. the spin effect has the advantage that it already appears in a bragg scattering setup with arbitrary low field amplitudes, for which we have estimated the diffraction count rate in a realistic experimental setup at available x - ray free - electron laser facilities. | arxiv:2001.10177 |
we present the results of 37 nights of ccd unfiltered photometry of nova v2574 oph ( 2004 ) from 2004 and 2005. we find two periods of 0. 14164 d ( ~ 3. 40 h ) and 0. 14773 d ( ~ 3. 55 h ) in the 2005 data. the 2004 data show variability on a similar timescale, but no coherent periodicity was found. we suggest that the longer periodicity is the orbital period of the underlying binary system and that the shorter period represents a negative superhump. the 3. 40 h period is about 4 % shorter than the orbital period and obeys the relation between superhump period deficit and binary period. the detection of superhumps in the light curve is evidence of the presence of a precessing accretion disk in this binary system shortly after the nova outburst. from the maximum magnitude - rate of decline relation, we estimate the decay rate t _ 2 = 17 + / - 4 d and a maximum absolute visual magnitude of m _ vmax = - 7. 7 + / - 1. 7 mag. | arxiv:astro-ph/0512483 |
we continue our investigation of $ e $ - operators, in particular their connection with $ g $ - operators ; these differential operators are fundamental in understanding the diophantine properties of siegel ' s $ e $ and $ g $ - functions. we study in detail microsolutions ( in kashiwara ' s sense ) of fuchsian differential operators, and apply this to the construction of basis of solutions at $ 0 $ and $ \ infty $ of any $ e $ - operator from microsolutions of a $ g $ - operator ; this provides a constructive proof of a theorem of andr \ ' e. we also focus on the arithmetic nature of connection constants and stokes constants between different bases of solutions of $ e $ - operators. for this, we introduce and study in details an arithmetic ( inverse ) laplace transform that enables one to get rid of transcendental numbers inherent to andr \ ' e ' s original approach. as an application, we define a set of special values of arithmetic gevrey series, and discuss its conjectural relation with the ring of exponential periods. | arxiv:1506.03574 |
recently a dynamical selection mechanism for vacua based on search optimization was proposed in the context of false - vacuum eternal inflation on the landscape. the search algorithm, defined by local vacuum transitions, is optimal in regions of the landscape where the dynamics are tuned at criticality, with de sitter vacua having an average lifetime of order their page time. the purpose of this paper is to shed light on the nature of the dynamical phase transition at the page lifetime. we focus on a finite region of the landscape, which exchanges volume with the rest of the landscape and as such acts as an open system. through a change of variables the master equation governing the comoving volume of de sitter vacua is mapped to a stochastic equation for coupled overdamped stochastic oscillators - - the well - known ornstein - uhlenbeck process. the rest of the landscape, which acts as an environment, is assumed to result in a non - vanishing driving term for all sites in the region with uncorrelated, white noise fluctuations ( though not necessarily gaussian ). we first show that the static susceptibility of the oscillators diverges as the average lifetime of de sitter vacua approaches the page time. thus, optimal regions of the landscape are most susceptible to volume influx from their environing landscape. we then show that the displacement fluctuations for the oscillators exhibit a $ 1 / f $ power spectrum over a broad range of frequencies, precisely at the critical page lifetime distribution. a $ 1 / f $ power spectrum is a hallmark of non - equilibrium systems at criticality. in analogy with sand avalanches in the abelian sandpile or neuronal avalanches in the brain, de sitter vacua at criticality can be thought of as undergoing scale invariant volume fluctuation avalanches. | arxiv:2003.12594 |
we present deep spectroscopic and imaging data of the host galaxies of mrk 1014, iras 07598 + 6508, and mrk 231. these objects form part of both the qso and the ultraluminous infrared galaxy ( ulig ) families, and may represent a transition stage in an evolutionary scenario. our imaging shows that all three objects have highly perturbed hosts with tidal tails and destroyed disks, and appear to be in the final stages of major mergers. the host galaxies of the three objects have spectra typical of e + a galaxies, showing simultaneously features from an old and a young stellar component. we model spectra from different regions of the host galaxies using bruzual & charlot spectral synthesis models using two component models including an old underlying population and recent superposed starbursts. our results indicate a strong connection between interactions and vigorous bursts of star formation in these objects. we propose that the starburst ages found are indicative of young ages for the qso activity. the young starburst ages found are also consistent with the intermediate position of these objects in the far infrared color - color diagram. ( abridged ) | arxiv:astro-ph/0007002 |
we consider the renormalization group ( rg ) improved inflaton potential in unitarized higgs inflation where the original higgs inflation is unitarized by the addition of a real singlet scalar of sigma - model type. the sigma field coupling to the higgs, which is introduced to reproduce a large non - minimal coupling of the higgs below the sigma scalar threshold, also improves the standard model vacuum stability due to the rg running. furthermore, the same sigma field coupling determines the reheating temperature or the number of efoldings. considering the uncertainties in the number of efoldings in the model, we show that the loop - corrected spectral index and tensor - to - scalar ratio are consistent with nine - year wmap and new planck data within 1sigma. | arxiv:1301.1787 |
differentiable rendering techniques have recently shown promising results for free - viewpoint video synthesis of characters. however, such methods, either gaussian splatting or neural implicit rendering, typically necessitate per - subject optimization which does not meet the requirement of real - time rendering in an interactive application. we propose a generalizable gaussian splatting approach for high - resolution image rendering under a sparse - view camera setting. to this end, we introduce gaussian parameter maps defined on the source views and directly regress gaussian properties for instant novel view synthesis without any fine - tuning or optimization. we train our gaussian parameter regression module on human - only data or human - scene data, jointly with a depth estimation module to lift 2d parameter maps to 3d space. the proposed framework is fully differentiable with both depth and rendering supervision or with only rendering supervision. we further introduce a regularization term and an epipolar attention mechanism to preserve geometry consistency between two source views, especially when neglecting depth supervision. experiments on several datasets demonstrate that our method outperforms state - of - the - art methods while achieving an exceeding rendering speed. | arxiv:2411.11363 |
there is a fundamental trade - off between the communication cost and latency in information aggregation. aggregating multiple communication messages over time can alleviate overhead and improve energy efficiency on one hand, but inevitably incurs information delay on the other hand. in the presence of uncertain future inputs, this trade - off should be balanced in an online manner, which is studied by the classical dynamic tcp ack problem for a single information source. in this paper, we extend dynamic tcp ack problem to a general setting of collecting aggregate information from distributed and correlated information sources. in this model, distributed sources observe correlated events, whereas only a small number of reports are required from the sources. the sources make online decisions about their reporting operations in a distributed manner without prior knowledge of the local observations at others. our problem captures a wide range of applications, such as in - situ sensing, anycast acknowledgement and distributed caching. we present simple threshold - based competitive distributed online algorithms under different settings of intercommunication. our algorithms match the theoretical lower bounds in order of magnitude. we observe that our algorithms can produce satisfactory performance in simulations and practical testbed. | arxiv:1601.03147 |
coded distributed computation has become common practice for performing gradient descent on large datasets to mitigate stragglers and other faults. this paper proposes a novel algorithm that encodes the partial derivatives themselves and furthermore optimizes the codes by performing lossy compression on the derivative codewords by maximizing the information contained in the codewords while minimizing the information between the codewords. the utility of this application of coding theory is a geometrical consequence of the observed fact in optimization research that noise is tolerable, sometimes even helpful, in gradient descent based learning algorithms since it helps avoid overfitting and local minima. this stands in contrast with much current conventional work on distributed coded computation which focuses on recovering all of the data from the workers. a second further contribution is that the low - weight nature of the coding scheme allows for asynchronous gradient updates since the code can be iteratively decoded ; i. e., a worker ' s task can immediately be updated into the larger gradient. the directional derivative is always a linear function of the direction vectors ; thus, our framework is robust since it can apply linear coding techniques to general machine learning frameworks such as deep neural networks. | arxiv:2201.12990 |
large language models ( llms ) have shown remarkable progress in code generation, but their generated code often suffers from inefficiency, resulting in longer execution times and higher memory consumption. to address this issue, we propose \ textbf { effilearner }, a self - optimization framework that utilizes execution overhead profiles to improve the efficiency of llm - generated code. effilearner first generates code using an llm, then executes it locally to capture execution time and memory usage profiles. these profiles are fed back to the llm, which then revises the code to reduce overhead. to evaluate the effectiveness of effilearner, we conduct extensive experiments on the effibench, humaneval, and mbpp with 16 open - source and 6 closed - source models. our evaluation results demonstrate that through iterative self - optimization, effilearner significantly enhances the efficiency of llm - generated code. for example, the execution time ( et ) of starcoder2 - 15b for the effibench decreases from 0. 93 ( s ) to 0. 12 ( s ) which reduces 87. 1 % the execution time requirement compared with the initial code. the total memory usage ( tmu ) of starcoder2 - 15b also decreases from 22. 02 ( mb * s ) to 2. 03 ( mb * s ), which decreases 90. 8 % of total memory consumption during the execution process. the source code of effilearner was released in https : / / github. com / huangd1999 / effilearner | arxiv:2405.15189 |
quantum detector properties of the quantum point contact ( qpc ) are analyzed for arbitrary electron transparency and coupling strength to the measured system and are shown to be determined by the electron counting statistics. conditions of the quantum - limited operation of the qpc detector which prevent information loss through the scattering time and scattering phases are found for arbitrary coupling. we show that the phase information can be restored and used for the quantum - limited detection by inclusion of the qpc detector in the electronic mach - zehnder interferometer. | arxiv:cond-mat/0505647 |
quaternionic analysis offers a function theory focused on the concept of $ \ psi - $ hyperholomorphic functions defined as null solutions of the $ \ psi - $ fueter operator, where $ \ psi $ is an arbitrary orthogonal base ( called structural set ) of $ \ mathbb h ^ 4 $. the main goal of the present paper is to extend the results given in \ cite { bg2 }, where a fractional $ \ psi - $ hyperholomorphic function theory was developed. we introduce a quaternionic perturbed fractional $ \ psi - $ fueter operator calculus, where stokes and borel - pompeiu formulas in this perturbed fractional $ \ psi - $ fueter setting are presented. | arxiv:2111.05089 |
in this work, we propose a novel preconditioned krylov subspace method for solving an optimal control problem of wave equations, after explicitly identifying the asymptotic spectral distribution of the involved sequence of linear coefficient matrices from the optimal control problem. namely, we first show that the all - at - once system stemming from the wave control problem is associated to a structured coefficient matrix - sequence possessing an eigenvalue distribution. then, based on such a spectral distribution of which the symbol is explicitly identified, we develop an ideal preconditioner and two parallel - in - time preconditioners for the saddle point system composed of two block toeplitz matrices. for the ideal preconditioner, we show that the eigenvalues of the preconditioned matrix - sequence all belong to the set $ \ left ( - \ frac { 3 } { 2 }, - \ frac { 1 } { 2 } \ right ) \ bigcup \ left ( \ frac { 1 } { 2 }, \ frac { 3 } { 2 } \ right ) $ well separated from zero, leading to mesh - independent convergence when the minimal residual method is employed. the proposed { parallel - in - time } preconditioners can be implemented efficiently using fast fourier transforms or discrete sine transforms, and their effectiveness is theoretically shown in the sense that the eigenvalues of the preconditioned matrix - sequences are clustered around $ \ pm 1 $, which leads to rapid convergence. when these parallel - in - time preconditioners are not fast diagonalizable, we further propose modified versions which can be efficiently inverted. several numerical examples are reported to verify our derived localization and spectral distribution result and to support the effectiveness of our proposed preconditioners and the related advantages with respect to the relevant literature. | arxiv:2307.12850 |
the paper attempts to validate the effectiveness of tree classifiers to classify tabla strokes especially the ones which are overlapping in nature. it uses decision tree, id3 and random forest as classifiers. a custom made data sets of 650 samples of 13 different tabla strokes were used for experimental purpose. 31 different features with their mean and variances were extracted for classification. three data sets consisting of 21361, 18802 and 19543 instances respectively were used for the purpose. validation has been done using measures like roc curve and accuracy. the experimental results showed that all the classifiers showing excellent results with random forest outperforming the other two. the effectiveness of random forest in classifying strokes which are overlapping in nature is done by comparing the known results of that with multi - layer perceptron. | arxiv:1801.01712 |
code comments are important in software development because they directly influence software maintainability and overall quality. bad practices of code comments lead to code comment smells, negatively impacting software maintenance. recent research has been conducted on classifying inline code comment smells, yet automatically detecting these still remains a challenge. we aim to automatically detect and classify inline code comment smells through machine learning ( ml ) models and a large language model ( llm ) to determine how accurately each smell type can be detected. we enhanced a previously labeled dataset, where comments are labeled according to a determined taxonomy, by augmenting it with additional code segments and their associated comments. gpt 4, a large language model, was used to classify code comment smells on both the original and augmented datasets to evaluate its performance. in parallel, we trained and tested seven different machine learning algorithms on the augmented dataset to compare their classification performance against gpt 4. the performance of models, particularly random forest, which achieved an overall accuracy of 69 percent, along with gradient boosting and logistic regression, each achieving 66 percent and 65 percent, respectively, establishes a solid baseline for future research in this domain. the random forest model outperformed all other ml models, by achieving the highest matthews correlation coefficient ( mcc ) score of 0. 44. the augmented dataset improved the overall classification accuracy of the gpt 4 model predictions from 34 percent to 55 percent. this study contributes to software maintainability by exploring the automatic detection and classification of inline code comment smells. we have made our augmented dataset and code artifacts available online, offering a valuable resource for developing automated comment smell detection tools. | arxiv:2504.18956 |
we develop a practical approach to semidefinite programming ( sdp ) that includes the von neumann entropy, or an appropriate variant, as a regularization term. in particular we solve the dual of the regularized program, demonstrating how a carefully chosen randomized trace estimator can be used to estimate dual gradients effectively. we also introduce specialized optimization approaches for common sdp, specifically sdp with diagonal constraint and the problem of the determining the spectral projector onto the span of extremal eigenvectors. we validate our approach on such problems with applications to combinatorial optimization and spectral embedding. | arxiv:2303.12133 |
we present a dual isotope magneto optical trap produced using a single diode laser. we generate all the optical frequencies needed for trapping both species using a fiber intensity modulator. all the optical frequencies are amplified simultaneously using a tapered amplifier. the independent control of each frequency is on the rf side rather than on the optical side. this introduces an enormous simplification for laser cooling applications that often require an acousto - optic modulator for each laser beam. frequency changing capabilities are limited by the modulator bandwidth ( 10 ghz ). traps for more isotopes can be simply added by including additional rf frequencies to the modulator. | arxiv:1304.3702 |
rice has been one of the staple foods that contribute significantly to human food supplies. numerous rice varieties have been cultivated, imported, and exported worldwide. different rice varieties could be mixed during rice production and trading. rice impurities could damage the trust between rice importers and exporters, calling for the need to develop a rice variety inspection system. in this work, we develop a non - destructive rice variety classification system that benefits from the synergy between hyperspectral imaging and deep convolutional neural network ( cnn ). the proposed method uses a hyperspectral imaging system to simultaneously acquire complementary spatial and spectral information of rice seeds. the rice varieties are then determined from the acquired spatio - spectral data using a deep cnn. as opposed to several existing rice variety classification methods that require hand - engineered features, the proposed method automatically extracts spatio - spectral features from the raw sensor data. as demonstrated using two types of rice datasets, the proposed method achieved up to 11. 9 % absolute improvement in the mean classification accuracy, compared to the commonly used classification methods based on support vector machines. | arxiv:1805.11491 |
agricultural domains are being transformed by recent advances in ai and computer vision that support quantitative visual evaluation. using aerial and ground imaging over a time series, we develop a framework for characterizing the ripening process of cranberry crops, a crucial component for precision agriculture tasks such as comparing crop breeds ( high - throughput phenotyping ) and detecting disease. using drone imaging, we capture images from 20 waypoints across multiple bogs, and using ground - based imaging ( hand - held camera ), we image same bog patch using fixed fiducial markers. both imaging methods are repeated to gather a multi - week time series spanning the entire growing season. aerial imaging provides multiple samples to compute a distribution of albedo values. ground imaging enables tracking of individual berries for a detailed view of berry appearance changes. using vision transformers ( vit ) for feature detection after segmentation, we extract a high dimensional feature descriptor of berry appearance. interpretability of appearance is critical for plant biologists and cranberry growers to support crop breeding decisions ( e. g. \ comparison of berry varieties from breeding programs ). for interpretability, we create a 2d manifold of cranberry appearance by using a umap dimensionality reduction on vit features. this projection enables quantification of ripening paths and a useful metric of ripening rate. we demonstrate the comparison of four cranberry varieties based on our ripening assessments. this work is the first of its kind and has future impact for cranberries and for other crops including wine grapes, olives, blueberries, and maize. aerial and ground datasets are made publicly available. | arxiv:2412.09739 |
we investigate the idea of a " general boundary " formulation of quantum field theory in the context of the euclidean free scalar field. we propose a precise definition for an evolution kernel that propagates the field through arbitrary spacetime regions. we show that this kernel satisfies an evolution equation which governs its dependence on deformations of the boundary surface and generalizes the ordinary ( euclidean ) schroedinger equation. we also derive the classical counterpart of this equation, which is a hamilton - jacobi equation for general boundary surfaces. | arxiv:hep-th/0310246 |
we present an extension of quantum field theory to the case when the spacetime topology fluctuates ( spacetime foam ). in this extension the number of bosonic fields becomes a variable and the ground state is characterized by a finite particle number density. it is shown that when the number of fields remains a constant, the standard field theory is restored. however, in the complete theory the ground state has a nontrivial properties. in particular, it produces an increase in the level of quantum fluctuations in the field potentials and an additional renormalization of masses of particles. we examine fluctuations of massless fields and show that in the presence of a temperature ( thermal state ) these fluctuations has 1 / f spectrum. thus, the main prediction of the theory is that our universe should be filled with a random electromagnetic field which should produce an additional 1 / f - noise in electric circuits. | arxiv:hep-th/0012001 |
this paper presents mir - bft, a robust byzantine fault - tolerant ( bft ) total order broadcast protocol aimed at maximizing throughput on wide - area networks ( wans ), targeting deployments in decentralized networks, such as permissioned and proof - of - stake permissionless blockchain systems. mir - bft is the first bft protocol that allows multiple leaders to propose request batches independently ( i. e., parallel leaders ), in a way that precludes request duplication attacks by malicious ( byzantine ) clients, by rotating the assignment of a partitioned request hash space to leaders. as this mechanism removes a single - leader bandwidth bottleneck and exposes a computation bottleneck related to authenticating clients even on a wan, our protocol further boosts throughput using a client signature verification sharding optimization. our evaluation shows that mir - bft outperforms state - of - the - art and orders more than 60000 signed bitcoin - sized ( 500 - byte ) transactions per second on a widely distributed 100 nodes, 1 gbps wan setup, with typical latencies of few seconds. we also evaluate mir - bft under different crash and byzantine faults, demonstrating its performance robustness. mir - bft relies on classical bft protocol constructs, which simplifies reasoning about its correctness. specifically, mir - bft is a generalization of the celebrated and scrutinized pbft protocol. in a nutshell, mir - bft follows pbft " safety - wise ", with changes needed to accommodate novel features restricted to pbft liveness. | arxiv:1906.05552 |
in this paper, we present a transformer - based architecture, namely tf - grasp, for robotic grasp detection. the developed tf - grasp framework has two elaborate designs making it well suitable for visual grasping tasks. the first key design is that we adopt the local window attention to capture local contextual information and detailed features of graspable objects. then, we apply the cross window attention to model the long - term dependencies between distant pixels. object knowledge, environmental configuration, and relationships between different visual entities are aggregated for subsequent grasp detection. the second key design is that we build a hierarchical encoder - decoder architecture with skip - connections, delivering shallow features from encoder to decoder to enable a multi - scale feature fusion. due to the powerful attention mechanism, the tf - grasp can simultaneously obtain the local information ( i. e., the contours of objects ), and model long - term connections such as the relationships between distinct visual concepts in clutter. extensive computational experiments demonstrate that the tf - grasp achieves superior results versus state - of - art grasping convolutional models and attain a higher accuracy of 97. 99 % and 94. 6 % on cornell and jacquard grasping datasets, respectively. real - world experiments using a 7dof franka emika panda robot also demonstrate its capability of grasping unseen objects in a variety of scenarios. the code and pre - trained models will be available at https : / / github. com / wangshaosun / grasp - transformer | arxiv:2202.11911 |
we investigate electronic transport in twisted bilayer graphene ( tblg ) under variable temperatures ( $ t $ ), carrier densities ( $ n $ ), and transverse magnetic fields, focusing on samples with small - twist - angles ( $ \ theta $ ). these samples show prominent signatures associated with the van hove singularities ( vhss ) and superlattice - induced mini - gaps ( smgs ). temperature - dependent field effect measurement shows that the difference between temperature - dependent resistivity and residual resistivity, $ \ rho _ { xx } ( n, t ) - \ rho _ { 0 } ( n ) $, follows $ ~ t ^ \ beta $ for $ n $ between the main dirac point ( dp ) and smg. the evolution of the temperature exponent $ \ beta $ with $ n $ exhibits a w - shaped dependence, with minima of $ \ beta $ ~ 0. 9 near the vhss and maxima of $ \ beta $ ~ 1. 7 toward the smgs. this w - shaped behavior can be qualitatively understood with a theoretical picture that considers both the fermi surface smearing near the vhss and flexural - acoustic phonon scattering. in the quantum hall regime, we observe only landau level crossings in the massless dirac spectrum originating from the main dp but not in the parabolic band near the smg. such crossings enable the measurement of an enhanced interlayer dielectric constant, attributed to a reduced fermi velocity. moreover, we measure the fermi velocity, interlayer coupling strength, vhs energy relative to the dp, and gap size of smg, four important parameters used to describe the peculiar band structure of the small - $ \ theta $ tblg. | arxiv:1805.01454 |
we present the first analytical superposition of a charged black hole with an annular disk of extremal dust. in order to obtain the solutions, we first solve the einstein - maxwell field equations for sources that represent disk - like configurations of matter in confomastatic spacetimes by assuming a functional dependence among the metric function, the electric potential and an auxiliary function, which is taken as a solution of the laplace equation. we then employ the lord kelvin inversion method applied to models of finite extension in order to obtain annular disks. the structures obtained extend to infinity, but their total masses are finite and all the energy conditions are satisfied. finally, we observe that the extremal reissner - nordstr \ " { o } m black hole can be embedded into the center of the disks by adding a boundary term in the inversion. | arxiv:1009.1005 |
in this paper we will make the computation of the onsager - machlup functional of an inhomogeneous uniformly elliptic diffusion process. this functional will have formally the same picture as in the homogeneous case, the only difference come from the infinitesimal variation of the volume. for example in the ricci flow case, we find some functional which is not so far to the $ \ mathcal l _ { 0 } $ distance used by lott to study this flow \ cite { lott : 08 }. we finish by a application to small ball probability for weighted sup norm, for inhomogeneous diffusion. | arxiv:1104.2678 |
eddy current separation ( ecs ) is a process used throughout the scrap recycling industry for separating nonferrous metals from nonmetallic fluff. to date, however, the physical theory of ecs has generally been limited to empirical approximations and numerical simulations. we therefore introduce a simplified, two - dimensional model for ecs based on a cylindrical array of permanent, alternating magnets. the result is a fourier - series expansion that describes the total magnetic field profile over all space. if the magnets are then rotated with constant angular velocity, the magnetic fields vary as a discrete series of sinusoidal harmonics, thereby inducing electrical eddy currents in nearby conductive particles. force and torque calculations can then be used to predict the corresponding kinematic trajectories. | arxiv:1804.02435 |
let $ \ lambda _ { 2 } ( g ) $ be the second smallest normalized laplacian eigenvalue of a graph $ g $. in this paper, we determine all unicyclic graphs of order $ n \ geq21 $ with $ \ lambda _ { 2 } ( g ) \ geq 1 - \ frac { \ sqrt { 6 } } { 3 } $. moreover, the unicyclic graphs with $ \ lambda _ { 2 } ( g ) = 1 - \ frac { \ sqrt { 6 } } { 3 } $ are also determined. | arxiv:1806.00513 |
a theory of a pseudogap phase of high - temperature superconductors where current carriers are translation invariant bipolarons is developed. a temperature t * of a transition from a pseudogap phase to a normal one is calculated. for the temperature of a transition to the pseudogap phase, the isotope coefficient is found. it is shown that the results obtained, in particular, the possibility of negative values of the isotope coefficient are consistent with the experiment. new experiments on the influence of the magnetic field on the isotope coefficient are proposed. | arxiv:2102.08762 |
iceberg of a promising number of such objects that will be uncovered in the upcoming full j - pas survey and deep ifu observations with 8 - 10m telescopes will be essential for constraining the underlying physical mechanism that is responsible for the double - cored morphology. | arxiv:2207.00196 |
the non - relativistic cross section from rayleigh scattering by hydrogen atoms in the ground state is calculated over a wide range of photon energies ( $ < 0. 8 $ kev ). evaluations are performed in terms of the real and imaginary components of the atomic polarizability. the sum over intermediate states that characterizes this second - order radiative process is performed using exact analytic expressions for oscillator strengths of bound and continuum states. damping terms associated with the finite lifetimes of excited states and their splitting into two fine - structure levels ( $ p _ { 1 / 2 } $ and $ p _ { 3 / 2 } $ ) are taken into account in resonance cross sections. fitting formulas required for cross - section evaluation are presented for incident photon energy i ) redward of the first resonance ( lyman - $ \ alpha _ { 1 / 2 } $ ), ii ) in the spectral region corresponding to resonances ( for an arbitrary number of them ), and iii ) above the ionization threshold. | arxiv:2208.02111 |
we introduce a universal framework for characterizing the statistical efficiency of a statistical estimation problem with differential privacy guarantees. our framework, which we call high - dimensional propose - test - release ( hptr ), builds upon three crucial components : the exponential mechanism, robust statistics, and the propose - test - release mechanism. gluing all these together is the concept of resilience, which is central to robust statistical estimation. resilience guides the design of the algorithm, the sensitivity analysis, and the success probability analysis of the test step in propose - test - release. the key insight is that if we design an exponential mechanism that accesses the data only via one - dimensional robust statistics, then the resulting local sensitivity can be dramatically reduced. using resilience, we can provide tight local sensitivity bounds. these tight bounds readily translate into near - optimal utility guarantees in several cases. we give a general recipe for applying hptr to a given instance of a statistical estimation problem and demonstrate it on canonical problems of mean estimation, linear regression, covariance estimation, and principal component analysis. we introduce a general utility analysis technique that proves that hptr nearly achieves the optimal sample complexity under several scenarios studied in the literature. | arxiv:2111.06578 |
methodology is proposed to uncover structural breaks in functional data that is " fully functional " in the sense that it does not rely on dimension reduction techniques. a thorough asymptotic theory is developed for a fully functional break detection procedure as well as for a break date estimator, assuming a fixed break size and a shrinking break size. the latter result is utilized to derive confidence intervals for the unknown break date. the main results highlight that the fully functional procedures perform best under conditions when analogous fpca based estimators are at their worst, namely when the feature of interest is orthogonal to the leading principal components of the data. the theoretical findings are confirmed by means of a monte carlo simulation study in finite samples. an application to annual temperature curves illustrates the practical relevance of the proposed procedures. | arxiv:1511.04020 |
van der waals heterostructures built by vertically stacked transition metal dichalcogenides ( tmds ) exhibit a rich energy landscape including interlayer and intervalley excitons. recent experiments demonstrated an ultrafast charge transfer in tmd heterostructures. however, the nature of the charge transfer process has remained elusive. based on a microscopic and material - realistic exciton theory, we reveal that phonon - mediated scattering via strongly hybridized intervalley excitons governs the charge transfer process that occurs on a sub - 100fs timescale. we track the time -, momentum -, and energy - resolved relaxation dynamics of optically excited excitons and determine the temperature - and stacking - dependent charge transfer time for different tmd bilayers. the provided insights present a major step in microscopic understanding of the technologically important charge transfer process in van der waals heterostructures. | arxiv:2209.03779 |
this paper is a survey on the lickorish type construction of some kind of closed manifolds over simple convex polytopes. inspired by lickorish ' s theorem, we propose a method to describe certain families of manifolds over simple convex polytopes with torus action. under this construction, many classical classification results of these families of manifolds could be interpreted by this construction and some further problems will be discussed. | arxiv:1902.06895 |
we obtain a determinant expression for the tree - level structure constant of three non - extremal single - trace operators in the su ( 2 ) sector of planar n = 4 supersymmetric yang - mills theory. | arxiv:1111.4663 |
we show that hives chosen at random with independent gue boundary conditions on two sides, weighted by a vandermonde factor depending on the third side ( which is necessary in the context of the randomized horn problem ), when normalized so that the eigenvalues at the edge are asymptotically constant, converge in probability to a continuum hive as $ n \ rightarrow \ infty. $ it had previously been shown in joint work with sheffield and tao \ cite { nst } that the variance of these scaled random hives tends to $ 0 $ and consequently, from compactness, that they converge in probability subsequentially. in the present paper, building on \ cite { nst }, we prove convergence in probability to a single continuum hive, without having to pass to a subsequence. we moreover show that the value at a given point $ v $ of this continuum hive equals the supremum of a certain functional acting on asymptotic height functions of lozenge tilings. | arxiv:2502.06414 |
x - ray emission and absorption features are of great importance in our understanding the nature and environment of gamma - ray bursts ( grbs ). so far, iron emission lines have been detected in at least four grb afterglows. in this paper, the observational properties and physical constraints on materials surrounding grb sources are reviewed, and several classes of theoretical models are also discussed. we will specially concentrate on the cerenkov line mechanism, in which the broad iron lines are expected, and a small mass of fe is required to produce the large line luminosity. in addition, our interpretation can favor the recent jet unified model for different classes of gamma - ray bursts with a standard energy reservoir. | arxiv:astro-ph/0407626 |
$ kepler $ revealed that roughly one - third of sun - like stars host planets orbiting within 100 days and between the size of earth and neptune. how do these planets form, what are they made of, and do they represent a continuous population or multiple populations? to help address these questions, we began the magellan - tess survey ( mts ), which uses magellan ii / pfs to obtain radial velocity ( rv ) masses of 30 tess - detected exoplanets and develops an analysis framework that connects observed planet distributions to underlying populations. in the past, small planet rv measurements have been challenging to obtain due to host star faintness and low rv semi - amplitudes, and challenging to interpret due to the potential biases in target selection and observation planning decisions. the mts attempts to minimize these biases by focusing on bright tess targets and employing a quantitative selection function and observing strategy. in this paper, we ( 1 ) describe our motivation and survey strategy, ( 2 ) present our first catalog of planet density constraints for 27 tess objects of interest ( tois ; 22 in our population analysis sample, 12 that are members of the same systems ), and ( 3 ) employ a hierarchical bayesian model to produce preliminary constraints on the mass - radius ( m - r ) relation. we find that the biases causing previous m - r relations to predict fairly high masses at $ 1 ~ r _ \ oplus $ have been reduced. this work can inform more detailed studies of individual systems and offer a framework that can be applied to future rv surveys with the goal of population inferences. | arxiv:2011.11560 |
non - baryonic, or " dark, " matter is believed to be a major component of the total mass budget of the universe. we review the candidates for particle dark matter and discuss the prospects for direct detection ( via interaction of dark matter particles with laboratory detectors ) and indirect detection ( via observations of the products of dark matter self - annihilations ), focusing in particular on the galactic center, which is among the most promising targets for indirect detection studies. the gravitational potential at the galactic center is dominated by stars and by the supermassive black hole, and the dark matter distribution is expected to evolve on sub - parsec scales due to interaction with these components. we discuss the dominant interaction mechanisms and show how they can be used to rule out certain extreme models for the dark matter distribution, thus increasing the information that can be gleaned from indirect detection searches. | arxiv:astro-ph/0504422 |
sparse - group lasso ( sgl ) has been shown to be a powerful regression technique for simultaneously discovering group and within - group sparse patterns by using a combination of the $ \ ell _ 1 $ and $ \ ell _ 2 $ norms. however, in large - scale applications, the complexity of the regularizers entails great computational challenges. in this paper, we propose a novel two - layer feature reduction method ( tlfre ) for sgl via a decomposition of its dual feasible set. the two - layer reduction is able to quickly identify the inactive groups and the inactive features, respectively, which are guaranteed to be absent from the sparse representation and can be removed from the optimization. existing feature reduction methods are only applicable for sparse models with one sparsity - inducing regularizer. to our best knowledge, tlfre is the first one that is capable of dealing with multiple sparsity - inducing regularizers. moreover, tlfre has a very low computational cost and can be integrated with any existing solvers. we also develop a screening method - - - called dpc ( decomposition of convex set ) - - - for the nonnegative lasso problem. experiments on both synthetic and real data sets show that tlfre and dpc improve the efficiency of sgl and nonnegative lasso by several orders of magnitude. | arxiv:1410.4210 |
socioeconomic inequalities in cities are embedded in space and result in neighborhood effects, whose harmful consequences have proved very hard to counterbalance efficiently by planning policies alone. considering redistribution of money flows as a first step toward improved spatial equity, we study a bottom - up approach that would rely on a slight evolution of shopping mobility practices. building on a database of anonymized credit card transactions in madrid and barcelona, we quantify the mobility effort required to reach a reference situation where commercial income is evenly shared among neighborhoods. the redirections of shopping trips preserve key properties of human mobility, including travel distances. surprisingly, for both cities only a small fraction ( $ \ sim 5 \ % $ ) of trips need to be altered to reach equity situations, improving even other sustainability indicators. the method could be implemented in mobile applications that would assist individuals in reshaping their shopping practices, to promote the spatial redistribution of opportunities in the city. | arxiv:1604.08394 |
the low - energy two neutrino - two photon interactions in the presence of homogeneous magnetic field are studied. the cross sections in external magnetic field are shown to be larger than in vacuum by factor $ \ sim ( m _ w / m _ e ) ^ 4 ( b / b _ c ) ^ 2 $. the energy - loss rate due to the process $ \ gamma \ gamma \ to \ nu \ bar { \ nu } $ in magnetic field is obtained. | arxiv:hep-ph/9709420 |
let $ g _ 1 $ be a semisimple real lie group and $ g _ 2 $ another locally compact second countable unimodular group. we prove that $ g _ 1 \ times g _ 2 $ has fixed price one if $ g _ 1 $ has higher rank, or if $ g _ 1 $ has rank one and $ g _ 2 $ is a $ p $ - adic split reductive group of rank at least one. as an application we resolve a question of gaboriau showing $ sl ( 2, \ mathbb { q } ) $ has fixed price one. inspired by the very recent work arxiv : 2307. 01194v1 [ math. gt ], we employ the method developed by the author and mikl \ ' os ab \ ' ert to show that all essentially free probability measure preserving actions of groups weakly factor onto the cox process driven by their amenable subgroups. we then show that if an amenable subgroup can be found satisfying a double recurrence property then the cox process driven by it has cost one. | arxiv:2307.11728 |
consider the time - periodic viscous incompressible fluid flow past a body with non - zero velocity at infinity. this article gives sufficient conditions such that weak solutions to this problem are smooth. since time - periodic solutions do not have finite kinetic energy in general, the well - known regularity results for weak solutions to the corresponding initial - value problem cannot be transferred directly. the established regularity criterion demands a certain integrability of the purely periodic part of the velocity field or its gradient, but it does not concern the time mean of these quantities. | arxiv:2212.00429 |
the effect of matter enhanced neutrino oscillations on atmosheric neutrinos is investigated systematically in the framework of one mass dominant model of three neutrinos. the resonance conditions of neutrino crossing the earth are determined by the three parameters, namely, the zenith angle, $ { \ delta m ^ 2 / e } $, and the mixing angle $ { \ theta _ 3 } $ of the electron neutrinos with tau neutrinos. the values of the triplet under the resonance is found numerically. | arxiv:hep-ph/0005008 |
in this paper we continue the study on intrinsic harnack inequality for non - homogeneous parabolic equations in non - divergence form initiated by the first author in [ 1 ]. we establish a forward - in - time intrinsic harnack inequality, which in particular implies the h \ " older continuity of the solutions. we also provide a harnack type estimate on global scale which quantifies the strong minimum principle. in the time - independent setting, this together with [ 1 ] provides an alternative proof of the generalized harnack inequality proven by the second author in [ 9 ]. | arxiv:2405.03283 |
containerization is a virtualization technique that allows one to create and run executables consistently on any infrastructure. compared to virtual machines, containers are lighter since they do not bundle a ( guest ) operating system but they share its kernel, and they only include the files, libraries, and dependencies that are required to properly execute a process. in the past few years, multiple container engines ( i. e., tools for configuring, executing, and managing containers ) have been developed ranging from some that are ` ` general purpose ' ', and mostly employed for cloud executions, to others that are built for specific contexts, namely internet of things and high - performance computing. given the importance of this technology for many practitioners and researchers, this paper analyses six state - of - the - art container engines and compares them through a comprehensive study of their characteristics and performance. the results are organized around 10 findings that aim to help the readers understand the differences among the technologies and help them choose the best approach for their needs. | arxiv:2303.04080 |
in undulatory mechanics the rest mass of a particle is associated to a rest periodicity known as compton periodicity. in carbon nanotubes the compton periodicity is determined geometrically, through dimensional reduction, by the circumference of the curled - up dimension, or by similar spatial constraints to the charge carrier wave function in other condensed matter systems. in this way the compton periodicity is effectively reduced by several order of magnitudes with respect to that of the electron, allowing for the possibility to experimentally test foundational aspects of quantum mechanics. we present a novel powerful formalism to derive the electronic properties of carbon nanotubes, in agreement with the results known in the literature, from simple geometric and relativistic considerations about the compton periodicity as well as a dictionary of analogies between particle and graphene physics. | arxiv:1403.7037 |
sr _ 2cu _ 3o _ 4cl _ 2 is an antiferromagnet consisting of weakly coupled cuo planes which comprise two weakly interacting antiferromagnetic subsystems, i and ii, which order at respective temperatures t _ i \ approx 390k and t _ { ii } \ approx 40k. except asymptotically near the ordering temperature, these systems are good representations of the two - dimensional quantum spin 1 / 2 heisenberg model. for t < t _ { ii } there are four low - energy modes at zero wave vector, three of whose energies are dominated by quantum fluctuations. for t _ { ii } < t < t _ i there are two low energy modes. the mode with lower energy is dominated by quantum fluctuations. our calculations of the energies of these modes ( including dispersion for wave vectors perpendicular to the cuo planes ) agree extremely well with the experimental results of inelastic neutron scattering ( in the accompanying paper ) and for modes in the sub mev range observed by electron spin resonance. the parameters needed to describe quantum fluctuations are either calculated here or are taken from the literature. these results show that we have a reasonable qualitative understanding of the band structure of the lamellar cuprates needed to calculate the anisotropic exchange constants used here. | arxiv:cond-mat/0009315 |
the polarisation conversion of a linear polarised electromagnetic wave incident onto a two - dimensional ( 2d ) electron system at an angle is theoretically studied. we consider the 2d system located at the interface between two dielectric media with different dielectric constants. an external dc magnetic field is assumed to be directed along the normal to the 2d electron layer. in such a configuration the cyclotron - polaritons ( cps ) in 2d electron system can be excited with the frequencies in the vicinity of the cyclotron frequency. under the cps excitation the resonance polarisation conversion of electromagnetic wave greatly increases in the system. in the absence of the electron scattering in 2d system, the polarisation conversion reaches 100 % at a certain value of the angle of incidence which is more than the total reflection angle. extremely high polarisation conversion takes place in a quite wide range of variation of the angle of incidence. high polarisation conversion efficiency ( above 80 % ) remains when the actual electron scattering in the 2d system on gsas is taken into account. the considered phenomena may be taken up in polarisation spectroscopy of 2d electron systems. | arxiv:cond-mat/0101072 |
diffusion probabilistic models ( dpms ) have exhibited excellent performance for high - fidelity image generation while suffering from inefficient sampling. recent works accelerate the sampling procedure by proposing fast ode solvers that leverage the specific ode form of dpms. however, they highly rely on specific parameterization during inference ( such as noise / data prediction ), which might not be the optimal choice. in this work, we propose a novel formulation towards the optimal parameterization during sampling that minimizes the first - order discretization error of the ode solution. based on such formulation, we propose dpm - solver - v3, a new fast ode solver for dpms by introducing several coefficients efficiently computed on the pretrained model, which we call empirical model statistics. we further incorporate multistep methods and a predictor - corrector framework, and propose some techniques for improving sample quality at small numbers of function evaluations ( nfe ) or large guidance scales. experiments show that dpm - solver - v3 achieves consistently better or comparable performance in both unconditional and conditional sampling with both pixel - space and latent - space dpms, especially in 5 $ \ sim $ 10 nfes. we achieve fids of 12. 21 ( 5 nfe ), 2. 51 ( 10 nfe ) on unconditional cifar10, and mse of 0. 55 ( 5 nfe, 7. 5 guidance scale ) on stable diffusion, bringing a speed - up of 15 % $ \ sim $ 30 % compared to previous state - of - the - art training - free methods. code is available at https : / / github. com / thu - ml / dpm - solver - v3. | arxiv:2310.13268 |
we study max - plus convexity in an archimedean riesz space $ e $ with an order unit $ \ un $ ; the definition of max - plus convex sets is algebraic and we do not assume that $ e $ has an { \ it a priori } given topological structure. to the given unit $ \ un $ one can associate two equivalent norms $ \ norm \ cdot \ norm _ { \ un } $ and $ \ norm \ cdot \ norm _ { \ hun } $ on $ e $ ; the distance $ { \ sf d } _ { \ hun } $ on $ e $ associated to $ \ norm \ cdot \ norm _ { \ hun } $ is a geodesic distance for which max - plus convex sets in $ e $ are geodesically closed sets. under suitable assumptions, we establish max - plus versions of some fixed points and continuous selection theorems that are well known for linear convex sets and we show that hyperspaces of compact max - plus convex sets are absolute retracts. | arxiv:1905.00946 |
we study quantum mechanical tunneling using complex solutions of the classical field equations. simple visualization techniques allow us to unify and generalize previous treatments, and straightforwardly show the connection to the standard approach using euclidean instanton solutions. we demonstrate that the negative modes of solutions along various contours in the complex time plane reveal which paths give the leading contribution to tunneling and which do not, and we provide a criterion for identifying the negative modes. central to our approach is the solution of the background and perturbation equations not only along a single path, but over an extended region of the complex time plane. our approach allows for a fully continuous and coherent treatment of classical evolution interspersed by quantum tunneling events, and is applicable in situations where singularities are present and also where euclidean solutions might not exist. | arxiv:1605.02751 |
jefferson lab experiment e08 - 007 measured the proton elastic form factor ratio $ \ mu _ pg _ e / g _ m $ in the range of $ q ^ 2 = 0. 3 - 0. 7 ( \ mathrm { gev } / c ) ^ 2 $ by recoil polarimetry. data were taken in 2008 at the thomas jefferson national accelerator facility in virginia, usa. a 1. 2 gev polarized electron beam was scattered off a cryogenic hydrogen target. the recoil proton was detected in the left hrs in coincidence with the elasticly scattered electrons tagged by the bigbite spectrometer. the proton polarization was measured by the focal plane polarimeter ( fpp ). in this low $ q ^ 2 $ region, previous measurement from jefferson lab hall a ( ledex ) along with various fits and calculations indicate substantial deviations of the ratio from unity. for this new measurement, the proposed statistical uncertainty ( $ < 1 % $ ) was achieved. these new results are a few percent lower than expected from previous world data and fits, which indicate a smaller $ g _ { ep } $ at this region. beyond the intrinsic interest in nucleon structure, the new results also have implications in determining the proton zemach radius and the strangeness form factors from parity violation experiments. | arxiv:1108.4441 |
( abridged ) we present the results of studying the spectral and photometric variability of the luminous blue variable star v532 in m33. the photometric variations are traced from 1960 to 2010, spectral variations - from 1992 to 2009. the star has revealed an absolute maximum of visual brightness ( 1992 - 1994, high / cold state ) and an absolute minimum ( 2007 - 2008, low / hot state ). the variability of the spectrum of v532 is fully consistent with the temperature variations in its photosphere, while both permitted and forbidden lines are formed in an extended stellar atmosphere. broad components of the brightest lines were found, the broadening of these components is due to electron scattering in the wind parts closest to the photosphere. the wind velocity clearly depends on the size of the stellar photosphere or on the visual brightness, when brightness declines, the wind velocity increases. in the absolute minimum a kinematic profile of the v532 atmosphere was detected. the wind velocity increases and its temperature declines with distance from the star. in the low / hot state, the spectral type of the star corresponds to wn8. 5h, in the high / cold state - to wn11. we studied the evolution of v532 along with the evolution of ag car and the massive wr binary hd5980 in smc. during their visual minima, all the three stars perfectly fit with the wnl star sequence by crowther and smith ( 1997 ). however, when visual brightness increases, all the three stars form a separate sequence. it is possible that this reflects a new property of lbv stars, namely, in the high / cold states they do not pertain to the bona fide wnl stars. | arxiv:1105.0123 |
retinal vessel segmentation is critical for diagnosing ocular conditions, yet current deep learning methods are limited by modality - specific challenges and significant distribution shifts across imaging devices, resolutions, and anatomical regions. in this paper, we propose grinadapt, a novel framework for source - free multi - target domain adaptation that leverages multi - view images to refine segmentation labels and enhance model generalizability for optical coherence tomography angiography ( octa ) of the fundus of the eye. grinadapt follows an intuitive three - step approach : ( i ) grounding images to a common anchor space via registration, ( ii ) integrating predictions from multiple views to achieve improved label consensus, and ( iii ) adapting the source model to diverse target domains. furthermore, grinadapt is flexible enough to incorporate auxiliary modalities such as color fundus photography, to provide complementary cues for robust vessel segmentation. extensive experiments on a multi - device, multi - site, and multi - modal retinal dataset demonstrate that grinadapt significantly outperforms existing domain adaptation methods, achieving higher segmentation accuracy and robustness across multiple domains. these results highlight the potential of grinadapt to advance automated retinal vessel analysis and support robust clinical decision - making. | arxiv:2503.05991 |
in visual recognition tasks, such as image classification, unsupervised learning exploits cheap unlabeled data and can help to solve these tasks more efficiently. we show that the recursive autoconvolution operator, adopted from physics, boosts existing unsupervised methods by learning more discriminative filters. we take well established convolutional neural networks and train their filters layer - wise. in addition, based on previous works we design a network which extracts more than 600k features per sample, but with the total number of trainable parameters greatly reduced by introducing shared filters in higher layers. we evaluate our networks on the mnist, cifar - 10, cifar - 100 and stl - 10 image classification benchmarks and report several state of the art results among other unsupervised methods. | arxiv:1606.00611 |
ensuring safety for autonomous robots operating in dynamic environments can be challenging due to factors such as unmodeled dynamics, noisy sensor measurements, and partial observability. to account for these limitations, it is common to maintain a belief distribution over the true state. this belief could be a non - parametric, sample - based representation to capture uncertainty more flexibly. in this paper, we propose a novel form of belief control barrier functions ( bcbfs ) specifically designed to ensure safety in dynamic environments under stochastic dynamics and a sample - based belief about the environment state. our approach incorporates provable concentration bounds on tail risk measures into bcbfs, effectively addressing possible multimodal and skewed belief distributions represented by samples. moreover, the proposed method demonstrates robustness against distributional shifts up to a predefined bound. we validate the effectiveness and real - time performance ( approximately 1khz ) of the proposed method through two simulated underwater robotic applications : object tracking and dynamic collision avoidance. | arxiv:2504.04097 |
in this paper, we give the general expressions for a special series of tree amplitudes of the yang - mills theory. this series of amplitudes have two adjacent massless spin - 1 particles with extra - dimensional momenta and any number of positive helicity gluons. with special helicity choices, we use the spinor helicity formalism to express these n - point amplitudes in compact forms, and find a clever way to use the bcfw recursion relations to prove the results. then these amplitudes are used to form the complete 1 - loop all - plus integrand with any number of gluons, expressed in the q - cut representation. | arxiv:1610.05013 |
a comprehensive census of galactic open cluster properties places unique constraints on the galactic disc structure and evolution. in this framework we investigate the evolutionary status of three poorly - studied open clusters, berkeley 31, berkeley 23 and king 8, all located in the galactic anti - centre direction. to this aim, we make use of deep lbt observations, reaching more than 6 mag below the main sequence turn - off. to determine the cluster parameters, namely age, metallicity, distance, reddening and binary fraction, we compare the observational colour - magnitude diagrams ( cmds ) with a library of synthetic cmds generated with different evolutionary sets ( padova, franec and fst ) and metallicities. we find that berkeley 31 is relatively old, with an age between 2. 3 and 2. 9 gyr, and rather high above the galactic plane, at about 700 pc. berkeley 23 and king 8 are younger, with best fitting ages in the range 1. 1 - 1. 3 gyr and 0. 8 - 1. 3 gyr, respectively. the position above the galactic plane is about 500 - 600 pc for the former, and 200 pc for the latter. although a spectroscopic confirmation is needed, our analysis suggests a sub - solar metallicity for all three clusters. | arxiv:1105.4440 |
a bounded linear operator $ a $ on a hilbert space $ \ mathcal { h } $ is posinormal if there exists a positive operator $ p $ such that $ aa ^ { * } = a ^ { * } pa $. we show that if $ a $ is posinormal with closed range, then $ a ^ n $ is posinormal and has closed range for all integers $ n \ ge 1 $. because the collection of posinormal operators includes all hyponormal operators, we obtain as a corollary that powers of closed - range hyponormal operators continue to have closed range. we also present a simple example of a closed - range operator $ t : \ mathcal { h } \ to \ mathcal { h } $ such that $ t ^ 2 $ does not have closed range. | arxiv:2203.01473 |
i re - examine a recent work by g. landi and g. e. landi. [ arxiv : 1808. 06708 [ physics. ins - det ] ], in which the authors claim that the resolution of a tracker ca vary linearly with the number of detection layers, $ n $, that is, faster than the commonly known $ \ sqrt { n } $ variation, for a tracker of fixed length, in case the precision of the position measurement is allowed to vary from layer to layer, i. e. heteroscedasticity, and an appropriate analysis method, a weighted least squares fit, is used. | arxiv:2010.03451 |
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