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we present the results of a detailed analysis of rxte observations which show an unusual state transition between high - soft and low - soft states in the microquasar grs 1915 + 105. the rxte pointed observations reveal that these events appeared as a series of quasi - regular dips when hard x - ray and radio flux were very low. the x - ray light curve and colour - colour diagram of the source during these observations are found to be different from any reported so far. the x - ray spectral and timing properties of the source during these dips are distinctly different from those seen during the other various dips and low intensity states seen in this source. there is, however, a remarkable similarity in the properties during the dip and non - dip regions in these set of observations. this indicates that the basic accretion disk structure is similar, but differ only in intensity. we invoke a model, to explain these observations, in which the viscosity is very close to a critical viscosity and the shock wave is weak or absent. | arxiv:astro-ph/0208109 |
in this article, we present a complete classification of the negative parity $ \ xi ' _ { c / b } $ and $ \ xi _ { c / b } $ $ p $ - wave states : 7 belonging to the $ su ( 3 ) $ flavor sextet and 7 to the flavor anti - triplet, the calculation of the $ \ xi ' _ { c / b } $ and $ \ xi _ { c / b } $ strong partial decay widths into $ ^ 2 \ sigma _ c \ bar { k } $, $ ^ 2 \ xi _ c ^ { ' } \ pi $, $ ^ 2 \ sigma _ c \ bar { k } $, $ ^ 4 \ xi _ c ^ { ' } \ pi $, $ \ lambda _ c ^ { ' } \ bar { k } $, $ \ xi _ c ^ { } \ pi $ and $ \ xi _ c ^ { } \ eta $ channels both within the elementary emission model ( eem ) and the $ ^ 3p _ 0 $ model, and the calculation of the electromagnetic decay widths for $ \ xi ' _ { c / b } $ and $ \ xi _ { c / b } $ radiative decays. by means of the equal - spacing mass rule and by the analysis of the strong partial decay widths, we suggest possible assignments for the new lhcb $ \ xi _ { c } ( 2923 ) $, $ \ xi _ { c } ( 2939 ) $, and $ \ xi _ { c } ( 2965 ) $ states, as well as for the $ \ xi _ { c } $ ' s previously reported by belle and babar. our results can be tested by future experiments, at lhcb and belle, disentangling the remaining missing piece of information, { \ it i. e. } the quantum numbers. finally, a comparison is made between a three - quark and a quark - diquark description of $ \ xi _ c $ states. very recently the lhcb collaboration reported the observation of two new $ \ xi _ b $ states, namely $ \ xi _ b ( 6327 ) ^ { 0 } $ and $ \ xi _ b ( 6333 ) $, in $ \ lambda _ b ^ 0 k ^ { - } \ pi ^ { + } $ channel with a statistical significance larger than nine standard deviations. the experimental masses and widths of these two states are consistent | arxiv:2010.12437 |
we study the restrictions imposed by cancellation of the tadpoles for two, three, and four - form gauge fields in string theory, m - theory and f - theory compactified to two, three and four dimensions, respectively. for a large class of supersymmetric vacua, turning on a sufficient number of strings, membranes and three - branes, respectively, can cancel the tadpoles, and preserve supersymmetry. however, there are cases where the tadpole cannot be removed in this way, either because the tadpole is fractional, or because of its sign. for m - theory and f - theory compactifications, we also explore the relation of the membranes and three - branes to the nonperturbative space - time superpotential. | arxiv:hep-th/9606122 |
$ \ mathbb { z } _ 2 $ topological insulators for photons and in general bosons cannot be strictly implemented because of the lack of symmetry - protected pseudospins. we show that the required protection can be provided by the real - space topological excitation of an interacting quantum fluid : quantum vortex. we consider a bose - einstein condensate at the $ \ gamma $ point of the brillouin zone of a quantum valley hall system based on two staggered honeycomb lattices. we demonstrate the existence of a coupling between the winding number of a vortex and the valley of the bulk bloch band. this leads to chiral vortex propagation at the zigzag interface between two regions of inverted staggering, where the winding - valley coupling provides true topological protection against backscattering, contrary to the interface states of the non - interacting hamiltonian. this configuration is an analog of a $ \ mathbb { z } _ 2 $ topological insulator for quantum vortices. | arxiv:1709.01830 |
we discovered new hidden symmetry of the one - dimensional hubbard model. we showthat the one - dimensional hubbard model on the infinite chain has the infinite - dimensional algebra of symmetries. this algebra is a direct sum of two $ sl ( 2 ) $ - yangians. this $ y ( sl ( 2 ) ) \ oplus y ( sl ( 2 ) ) $ symmetry is an extension of the well - known $ sl ( 2 ) \ oplus sl ( 2 ) $. the deformation parameters of the yangians are equal up to the signs to the coupling constant of the hubbard model hamiltonian. | arxiv:hep-th/9310158 |
among theoretical issues in general relativity the problem of constructing its hamiltonian formulation is still of interest. the most of attempts to quantize gravity are based upon dirac generalization of hamiltonian dynamics for system with constraints. at the same time there exists another way to formulate hamiltonian dynamics for constrained systems guided by the idea of extended phase space. we have already considered some features of this approach in the previous mg12 meeting by the example of a simple isotropic model. now we apply the approach to a generalized spherically symmetric model which imitates the structure of general relativity much better. in particular, making use of a global brst symmetry and the noether theorem, we construct the brst charge that generates correct gauge transformations for all gravitational degrees of freedom. | arxiv:1303.1308 |
a detailed investigation of a superconducting spin - triplet valve is presented. this spin - valve consists of a superconducting film covering a metal with an intrinsic spiral magnetic order, which could result from competing isotropic exchanges or, if the crystal lattice breaks central symmetry, from asymmetric dzyaloshinskii - moriya exchange. depending on the anisotropy, such a metal may change its magnetization either from a spiral to uniform order, as seen in ho and er, or in the direction of the spiral itself, as in crystals of the b20 - type structure ( such as mnsi, ( fe, co ) si, fege, etc. ). the nonuniform magnetic order controls the appearance of long - range triplet superconducting correlations at strong exchange fields, affecting the detailed character of the proximity effect. we show that the magnetic control of the spin - valve behavior can also be obtained from moderately low exchange fields ( typically associated to negligible long - range triplet correlations ), thanks to an orientation - dependent averaging mechanism of the magnetic inhomogeneity on the scale of the cooper pairs. our numerical calculations reveal that the spin - valve effect is in fact magnified at moderately low exchange fields, when the exchange splitting in the spiral magnet is comparable to the superconducting gap, and the spiral period is less than or equal to the superconducting coherence length in the magnet multiplied by $ 2 \ pi $. | arxiv:2110.00369 |
it is shown that epr correlations are the angular analogue to the hanbury - brown - - twiss effect. as insight provided by this model, it is seen that, analysis of the epr experiment requires conditional probabilities which do not admit the derivation of bell inequalities. | arxiv:quant-ph/9812072 |
we present smeftfr, a mathematica package designed to generate the feynman rules for the standard model effective field theory ( smeft ) including the complete set of gauge invariant operators up to dimension ~ 6. feynman rules are generated with the use of feynrules package, directly in the physical ( mass eigenstates ) basis for all fields. the complete set of interaction vertices can be derived including all or any chosen subset of smeft operators. as an option, the user can also choose preferred gauge fixing, generating feynman rules in unitary or $ r _ \ xi $ - gauges ( the latter include generation of ghost vertices ). further options allow to treat neutrino fields as massless weyl or massive majorana fermions. the derived lagrangian in the mass basis can be exported in various formats supported by feynrules, such as ufo, feynarts, etc. initialisation of numerical values of $ d = 6 $ wilson coefficients used by smeftfr is interfaced to wcxf format. the package also includes dedicated latex generator allowing to print the result in clear human - readable form. smeftfr can be downloaded from www. fuw. edu. pl / smeft. | arxiv:1904.03204 |
given two orientable, cusped hyperbolic 3 - manifolds containing certain thrice - punctured spheres, adams gave a diagrammatic definition for a third such manifold, their belted sum. fully augmented links, or fals, are hyperbolic links constructed by augmenting a link diagram. this work considers belted sum decompositions in which all manifolds involved are fal complements. to do so, we provide explicit classifications of thrice punctured spheres in fal complements, making them easily recognizable. these classifications are used to characterize belted sum prime fals geometrically, combinatorially and diagrammatically. finally we prove that, in the context of belted sums, every fal complement canonically decomposes into fals which are either prime or two - fold covers of the whitehead link. | arxiv:2311.13540 |
modern code review ( mcr ) is an informal tool - assisted quality assurance practice. it relies on the asynchronous communication among the authors of code changes and reviewers, who are developers that provide feedback. however, from candidate developers, some are able to provide better feedback than others given a particular context. the selection of reviewers is thus an important task, which can benefit from automated support. many approaches have been proposed in this direction, using for example data from code review repositories to recommend reviewers. in this paper, we propose the use of team - related features to improve the performance of predictions that are helpful to build code reviewer recommenders, with our target predictions being the identification of reviewers that would participate in a review and the provided amount of feedback. we evaluate the prediction power of these features, which are related to code ownership, workload, and team relationship. this evaluation was done by carefully addressing challenges imposed by the mcr domain, such as temporal aspects of the dataset and unbalanced classes. moreover, given that it is currently unknown how much past data is needed for building mcr prediction models with acceptable performance, we explore the amount of past data used to build prediction models. our results show that, individually, features related to code ownership have the best prediction power. however, based on feature selection, we conclude that all proposed features together with lines of code can make the best predictions for both reviewer participation and amount of feedback. regarding the amount of past data, the timeframes of 3, 6, 9, and 12 months of data produce similar results. therefore, models can be trained considering short timeframes, thus reducing the computational costs with negligible impact in the prediction performance... | arxiv:2312.06244 |
group - based sparse representation has shown great potential in image denoising. however, most existing methods only consider the nonlocal self - similarity ( nss ) prior of noisy input image. that is, the similar patches are collected only from degraded input, which makes the quality of image denoising largely depend on the input itself. however, such methods often suffer from a common drawback that the denoising performance may degrade quickly with increasing noise levels. in this paper we propose a new prior model, called group sparsity residual constraint ( gsrc ). unlike the conventional group - based sparse representation denoising methods, two kinds of prior, namely, the nss priors of noisy and pre - filtered images, are used in gsrc. in particular, we integrate these two nss priors through the mechanism of sparsity residual, and thus, the task of image denoising is converted to the problem of reducing the group sparsity residual. to this end, we first obtain a good estimation of the group sparse coefficients of the original image by pre - filtering, and then the group sparse coefficients of the noisy image are used to approximate this estimation. to improve the accuracy of the nonlocal similar patch selection, an adaptive patch search scheme is designed. furthermore, to fuse these two nss prior better, an effective iterative shrinkage algorithm is developed to solve the proposed gsrc model. experimental results demonstrate that the proposed gsrc modeling outperforms many state - of - the - art denoising methods in terms of the objective and the perceptual metrics. | arxiv:1703.00297 |
this paper is concerned with the problem of continuous - time nonlinear filtering for stochastic processes on a connected matrix lie group. the main contribution of this paper is to derive the feedback particle filter ( fpf ) algorithm for this problem. in its general form, the fpf is shown to provide a coordinate - free description of the filter that automatically satisfies the geometric constraints of the manifold. the particle dynamics are encapsulated in a stratonovich stochastic differential equation that retains the feedback structure of the original ( euclidean ) fpf. the implementation of the filter requires a solution of a poisson equation on the lie group, and two numerical algorithms are described for this purpose. as an example, the fpf is applied to the problem of attitude estimation - a nonlinear filtering problem on the lie group so ( 3 ). the formulae of the filter are described using both the rotation matrix and the quaternion coordinates. comparisons are also provided between the fpf and some popular algorithms for attitude estimation, namely the multiplicative ekf, the unscented quaternion estimator, the left invariant ekf, and the invariant ensemble kalman filter. numerical simulations are presented to illustrate the comparisons. | arxiv:1701.02416 |
our understanding of the brown dwarf population in star forming regions is dependent on knowing distances and proper motions, and therefore will be improved through the gaia space mission. in this paper, we select new samples of very low mass objects ( vlmos ) in upper scorpius using ukidss colors and optimised proper motions calculated using gaia dr1. the scatter in proper motions from vlmos in upper scorpius is now ( for the first time ) dominated by the kinematic spread of the region itself, not by the positional uncertainties. with age and mass estimates updated using gaia parallaxes for early type stars in the same region, we determine masses for all vlmos. our final most complete sample includes 453 vlmos of which $ \ sim $ 125 are expected to be brown dwarfs. the cleanest sample is comprised of 131 vlmos, with $ \ sim $ 105 brown dwarfs. we also compile a joint sample from the literature which includes 415 vlmos, out of which 152 are likely brown dwarfs. the disc fraction among low - mass brown dwarfs ( $ m < 0. 05 m _ { \ odot } $ ) is substantially higher than in more massive objects, indicating that discs around low - mass brown dwarfs survive longer than in low - mass stars overall. the mass function for $ 0. 01 < m < 0. 1 $ $ m _ { \ odot } $ is consistent with the kroupa imf. we investigate the possibility that some ' proper motion outliers ' have undergone a dynamical ejection early in their evolution. our analysis shows that the color - magnitude cuts used when selecting samples introduce strong bias into the population statistics due to varying level of contamination and completeness. | arxiv:1710.11625 |
this paper has been withdrawn | arxiv:hep-th/0507254 |
when magnetic field lines thread a rotating black hole ' s horizon and connect with remote astrophysical loads, the rotational energy of the black hole can be extracted through the blandford - znajek mechanism. due to the rotation of the black hole, the magnetic field lines are twisted and toroidal components are generated. so poloidal electric currents are induced and the black hole ' s rotational energy is transported to the astrophysical loads through poynting flux. the blandford - znajek mechanism has been considered to be a possible process for powering extragalactic jets. in this paper we show that due to the screw instability of magnetic field, the toroidal components of the magnetic field, and thus the poloidal currents, cannot exceed the limits given by the kruskal - shafranov criterion. this significantly lowers the power of the blandford - znajek mechanism when the loads are far from the black hole. so the blandford - znajek mechanism can only work efficiently within the neighborhood of the black hole. the implications of the results for the scenario of extragalactic jets powered by the blandford - znajek mechanism are discussed. | arxiv:astro-ph/0001420 |
we report on the computation of a class of massless bosonic three - loop vacuum sum - integrals which are key building blocks for an evaluation of the debye screening mass in hot qcd. generalizing known techniques and introducing the concept of tensor reduction by dimensionality shifts ( known to the zero - temperature community since the work of tarasov in 1996 ) to finite temperature, we are able to treat hitherto unaccessible cases, which will allow us to finalize the long - term project of nnlo debye mass evaluation. | arxiv:1208.0284 |
previously, it was believed that conduction and valence bands exhibit a symmetry : they possess opposite topological invariants ( e. g., the chern numbers of conduction and valence bands for the chern insulator are $ \ pm c $ ). however, we present a counterexample : the second stiefel - whitney numbers for conduction and valence bands over the klein bottle may be asymmetric, with one being nontrivial while the other trivial. here, the stiefel - whitney classes are the characteristic classes for real bloch functions under $ pt $ symmetry with $ ( pt ) ^ 2 = 1 $, and the klein bottle is the momentum - space unit under the projective anti - commutation relation of the mirror reflection reversing $ x $ and the translation along the $ y $ - direction. the asymmetry originates from the algebraic difference of real cohomology classes over klein bottle and torus. this discovery is rooted in the fundation of topological band theory, and has the potential to fundamentally refresh our current understanding of topological phases. | arxiv:2504.09524 |
for a given set of nodes in the plane the min - power centre is a point such that the cost of the star centred at this point and spanning all nodes is minimised. the cost of the star is defined as the sum of the costs of its nodes, where the cost of a node is an increasing function of the length of its longest incident edge. the min - power centre problem provides a model for optimally locating a cluster - head amongst a set of radio transmitters, however, the problem can also be formulated within a bicriteria location model involving the 1 - centre and a generalized fermat - weber point, making it suitable for a variety of facility location problems. we use farthest point voronoi diagrams and delaunay triangulations to provide a complete geometric description of the min - power centre of a finite set of nodes in the euclidean plane when cost is a quadratic function. this leads to a new linear - time algorithm for its construction when the convex hull of the nodes is given. we also provide an upper bound for the performance of the centroid as an approximation to the quadratic min - power centre. finally, we briefly describe the relationship between solutions under quadratic cost and solutions under more general cost functions. | arxiv:1307.1222 |
light - pulse atom interferometers are powerful quantum sensors, however, their accuracy for example in tests of the weak equivalence principle is limited by various spurious influences like magnetic stray fields or blackbody radiation. pushing the accuracy therefore requires a detailed assessment of the size of such deleterious effects. here, we present a systematic operator expansion to obtain phase shifts and contrast analytically in powers of the perturbation. the result can either be employed for robust straightforward order - of - magnitude estimates or for rigorous calculations. together with general conditions for the validity of the approach, we provide a particularly useful formula for the phase including wave - packet effects. | arxiv:2003.02042 |
we report a dramatic orbital modulation in the scintillation timescale of the relativistic binary pulsar j1141 - - 6545 that both confirms the validity of the scintillation speed methodology and enables us to derive important physical parameters. we have determined the space velocity, the orbital inclination and even the longitude of periastron of the binary system, which we find to be in good agreement with that obtained from pulse timing measurements. our data permit two equally - significant physical interpretations of the system. the system is either an edge - on binary with a high space velocity ( $ \ sim 115 $ km s $ ^ { - 1 } $ ) or is more face - on with a much slower velocity ( $ \ sim 45 $ km s $ ^ { - 1 } $ ). we favor the former, as it is more consistent with pulse timing and the distribution of known neutron star masses. under this assumption, the runaway velocity of 115 km s $ ^ { - 1 } $ is much greater than is expected if pulsars do not receive a natal kick at birth. the derived inclination of the binary system is ( 76 \ pm 2. 5 ^ { \ circ } ) degrees, implying a companion mass of 1. 01 ( \ pm ) ~ 0. 02 m ( _ { \ odot } ) and a pulsar mass of 1. 29 ( \ pm ) ~ 0. 02 m ( _ { \ odot } ). our derived physical parameters indicate that this pulsar should prove to be an excellent laboratory for tests of gravitational wave emission. | arxiv:astro-ph/0204421 |
image dehazing, a pivotal task in low - level vision, aims to restore the visibility and detail from hazy images. many deep learning methods with powerful representation learning capability demonstrate advanced performance on non - homogeneous dehazing, however, these methods usually struggle with processing high - resolution images ( e. g., $ 4000 \ times 6000 $ ) due to their heavy computational demands. to address these challenges, we introduce an innovative non - homogeneous dehazing method via deformable convolutional transformer - like architecture ( dehazedct ). specifically, we first design a transformer - like network based on deformable convolution v4, which offers long - range dependency and adaptive spatial aggregation capabilities and demonstrates faster convergence and forward speed. furthermore, we leverage a lightweight retinex - inspired transformer to achieve color correction and structure refinement. extensive experiment results and highly competitive performance of our method in ntire 2024 dense and non - homogeneous dehazing challenge, ranking second among all 16 submissions, demonstrate the superior capability of our proposed method. the code is available : https : / / github. com / movingforward100 / dehazing _ r. | arxiv:2407.05169 |
this study investigates the task of knowledge - based question generation ( kbqg ). conventional kbqg works generated questions from fact triples in the knowledge graph, which could not express complex operations like aggregation and comparison in sparql. moreover, due to the costly annotation of large - scale sparql - question pairs, kbqg from sparql under low - resource scenarios urgently needs to be explored. recently, since the generative pre - trained language models ( plms ) typically trained in natural language ( nl ) - to - nl paradigm have been proven effective for low - resource generation, e. g., t5 and bart, how to effectively utilize them to generate nl - question from non - nl sparql is challenging. to address these challenges, autoqgs, an auto - prompt approach for low - resource kbqg from sparql, is proposed. firstly, we put forward to generate questions directly from sparql for the kbqg task to handle complex operations. secondly, we propose an auto - prompter trained on large - scale unsupervised data to rephrase sparql into nl description, smoothing the low - resource transformation from non - nl sparql to nl question with plms. experimental results on the webquestionssp, comlexwebquestions 1. 1, and pathquestions show that our model achieves state - of - the - art performance, especially in low - resource settings. furthermore, a corpus of 330k factoid complex question - sparql pairs is generated for further kbqg research. | arxiv:2208.12461 |
several observations reveal that dwarf galaxy segue 1 has a dark matter ( dm ) halo at least ~ 200 times more massive than its visible baryon mass of only ~ 103 solar masses. the baryon mass is dominated by stars with perhaps an interstellar gas mass of < 13 solar masses. regarding segue 1 as a dwarf disc galaxy by its morphological appearance of long stretch, we invoke the dynamic model of xiang - gruess, lou & duschl ( xld ) to estimate its physical parameters for possible equilibria with and without an isopedically magnetized gas disc. we estimate the range of dm mass and compare it with available observational inferences. due to the relatively high stellar velocity dispersion compared to the stellar surface mass density, we find that a massive dm halo would be necessary to sustain disc equilibria. the required dm halo mass agrees grossly with observational inferences so far. for an isopedic magnetic field in a gas disc, the ratio f between the dm and baryon potentials depends strongly on the magnetic field strength. therefore, a massive dm halo is needed to counteract either the strong stellar velocity dispersion and rotation of the stellar disc or the magnetic lorentz force in the gas disc. by the radial force balances, the dm halo mass increases for faster disc rotation. | arxiv:0909.3496 |
we show that the triply graded khovanov - rozansky homology of the torus link $ t _ { n, k } $ stablizes as $ k \ to \ infty $. we explicitly compute the stable homology ( as a ring ), which proves a conjecture of gorsky - oblomkov - rasmussen - shende. to accomplish this, we construct complexes $ p _ n $ of soergel bimodules which categorify the young symmetrizers corresponding to one - row partitions and show that $ p _ n $ is a stable limit of rouquier complexes. a certain derived endomorphism ring of $ p _ n $ computes the aforementioned stable homology of torus links. | arxiv:1505.08148 |
in this note we present studies of coverage and power for confidence intervals for a poisson process with known background calculated using the likelihood ratio ( aka feldman & cousins ) ordering with bayesian treatment of uncertainties in nuisance parameters. we consider both the variant where the bayesian integration is done in both the numerator and the denominator and the modification where the integration is done only in the numerator whereas in the denominator the likelihood is taken at the maximum likelihood estimate of the parameters. furthermore we discuss how measurements can be combined in this framework and give an illustration with limits on the branching ratio of a rare b - meson decay recently presented by cdf / d0. a set of c + + classes has been developed which can be used to calculate confidence intervals for single or combining multiple experiments using the above algorithms and considering a variety of parameterizations to describe the uncertainties. | arxiv:physics/0511055 |
in this paper author was proved the boundedness of the multidimensional hardy type operator in weighted lebesgue spaces with a variable exponent. as an application we prove the boundedness of certain sublinear operators on the weighted variable lebesgue space. note that the proof of multidimensional hardy type operator in weighted lebesgue spaces with a variable exponent don ' t contained any mistakes. but at the proving of the boundedness of certain sublinear operators on the weighted variable lebesgue space georgian colleagues discovered a small but significant error in this paper. this result is assigned as theorem 5 in noted paper. in other words, sufficient conditions for general weights ensuring the validity of the two - weight strong type inequalities for some sublinear operator was found. in this theorem the inequality ( 9 ) isn ' t true. in this note we give the details of the correct argument. we presume that the reader is familiar with the contents and notation of our original paper. at the heart of our correction is the following theorem which replaces theorem 5. | arxiv:1303.0302 |
deep learning and convolutional neural networks ( cnn ) have been intensively used in many image processing topics during last years. as far as steganalysis is concerned, the use of cnn allows reaching the state - of - the - art results. the performances of such networks often rely on the size of their learning database. an obvious preliminary assumption could be considering that " the bigger a database is, the better the results are ". however, it appears that cautions have to be taken when increasing the database size if one desire to improve the classification accuracy i. e. enhance the steganalysis efficiency. to our knowledge, no study has been performed on the enrichment impact of a learning database on the steganalysis performance. what kind of images can be added to the initial learning set? what are the sensitive criteria : the camera models used for acquiring the images, the treatments applied to the images, the cameras proportions in the database, etc? this article continues the work carried out in a previous paper, and explores the ways to improve the performances of cnn. it aims at studying the effects of " base augmentation " on the performance of steganalysis using a cnn. we present the results of this study using various experimental protocols and various databases to define the good practices in base augmentation for steganalysis. | arxiv:1801.04076 |
contrary to wide - spread opinion that the final state interaction ( fsi ) enhances the amplitude < 2 \ pi ; i = 0 | k ^ 0 >, we argue that fsi does not increase the absolute value of this amplitude. | arxiv:0710.2774 |
we make use of a semi - analytical model of galaxy formation to investigate the origin of the observed correlation between [ a / fe ] abundance ratios and stellar mass in elliptical galaxies. we implement a new galaxy - wide stellar initial mass function ( top heavy integrated galaxy initial mass function, th - igimf ) in the semi - analytic model sag and evaluate its impact on the chemical evolution of galaxies. the sfr - dependence of the slope of the th - igimf is found to be key to reproducing the correct [ a / fe ] - stellar mass relation. massive galaxies reach higher [ a / fe ] abundance ratios because they are characterized by more top - heavy imfs as a result of their higher sfr. as a consequence of our analysis, the value of the minimum embedded star cluster mass and of the slope of the embedded cluster mass function, which are free parameters involved in the th - igimf theory, are found to be as low as 5 solar masses and 2, respectively. a mild downsizing trend is present for galaxies generated assuming either a universal imf or a variable th - igimf. we find that, regardless of galaxy mass, older galaxies ( with formation redshifts > 2 ) are formed in shorter time - scales ( < 2 gyr ), thus achieving larger [ a / fe ] values. hence, the time - scale of galaxy formation alone cannot explain the slope of the [ a / fe ] - galaxy mass relation, but is responsible for the big dispersion of [ a / fe ] abundance ratios at fixed stellar mass. we further test the hyphothesis of a th - igimf in elliptical galaxies by looking into mass - to - light ratios, and luminosity functions. models with a th - igimf are also favoured by these constraints. in particular, mass - to - light ratios agree with observed values for massive galaxies while being overpredicted for less massive ones ; this overprediction is present regardless of the imf considered. | arxiv:1402.3296 |
the trend of massive connectivity pushes forward the explosive growth of end devices. the emergence of various applications has prompted a demand for pervasive connectivity and more efficient computing paradigms. on the other hand, the lack of computational capacity of the end devices restricts the implementation of the intelligent applications, and becomes a bottleneck of the multiple access for supporting massive connectivity. mobile cloud computing ( mcc ) and mobile edge computing ( mec ) techniques enable end devices to offload local computation - intensive tasks to servers by networks. in this paper, we consider the cloud - edge - end collaborative networks to utilize distributed computing resources. furthermore, we apply task - oriented semantic communications to tackle the fast - varying channel between the end devices and mec servers and reduce the communication cost. to minimize long - term energy consumption on constraints queue stability and computational delay, a lyapunov - guided deep reinforcement learning hybrid ( drlh ) framework is proposed to solve the mixed integer non - linear programming ( minlp ) problem. the long - term energy consumption minimization problem is transformed into the deterministic problem in each time frame. the drlh framework integrates a model - free deep reinforcement learning algorithm with a model - based mathematical optimization algorithm to mitigate computational complexity and leverage the scenario information, so that improving the convergence performance. numerical results demonstrate that the proposed drlh framework achieves near - optimal performance on energy consumption while stabilizing all queues. | arxiv:2402.18183 |
the physical importance of the apparent discrepancy between the detections by pre - batse missions of absorption lines in gamma - ray burst spectra and the absence of a batse line detection necessitates a statistical analysis of this discrepancy. this analysis requires a calculation of the probability that a line, if present, will be detected in a given burst. however, the connection between the detectability of a line in a spectrum and in a burst requires a model for the occurrence of a line within a burst. we have developed the necessary weighting for the line detection probability for each spectrum spanning the burst. the resulting calculations require a description of each spectrum in the batse database. with these tools we identify the bursts in which lines are most likely to be detected. also, by assuming a small frequency with which lines occur, we calculate the approximate number of batse bursts in which lines of various types could be detected. lines similar to the ginga detections can be detected in relatively few batse bursts ; for example, in only ~ 20 bursts are lines similar to the gb 880205 pair of lines detectable. ginga reported lines at ~ 20 and ~ 40 kev whereas the low energy cutoff of the batse spectra is typically above 20 kev ; hence batse ' s sensitivity to lines is less than that of ginga below 40 kev, and greater above. therefore the probability that the gb 880205 lines would be detected in a ginga burst rather than a batse burst is ~ 0. 2. finally, we adopted a more appropriate test of the significance of a line feature. | arxiv:astro-ph/9703132 |
the equichordal point problem is a classical question in geometry, asking whether there exist multiple equichordal points within a single convex body. an equichordal point is defined as a point through which all chords of the convex body have the same length. this problem, initially posed by fujiwara and further investigated by blaschke, rothe, and weitzenb \ " ock, has remained an intriguing challenge, particularly in higher dimensions. in this paper, we rigorously prove the nonexistence of multiple equichordal points in $ n $ - dimensional convex bodies for $ n \ geq 2 $. by utilizing topological tools such as the borsuk - ulam theorem and analyzing the properties of continuous functions and mappings on convex bodies, we resolve this long - standing question. | arxiv:2501.02159 |
we present a self - supervised method to disentangle factors of variation in high - dimensional data that does not rely on prior knowledge of the underlying variation profile ( e. g., no assumptions on the number or distribution of the individual latent variables to be extracted ). in this method which we call nashae, high - dimensional feature disentanglement is accomplished in the low - dimensional latent space of a standard autoencoder ( ae ) by promoting the discrepancy between each encoding element and information of the element recovered from all other encoding elements. disentanglement is promoted efficiently by framing this as a minmax game between the ae and an ensemble of regression networks which each provide an estimate of an element conditioned on an observation of all other elements. we quantitatively compare our approach with leading disentanglement methods using existing disentanglement metrics. furthermore, we show that nashae has increased reliability and increased capacity to capture salient data characteristics in the learned latent representation. | arxiv:2209.10677 |
after formulating a no - go theorem for perfect quantum - classical hybrid systems, a new consistency requirement based on standard statistical considerations is noted. it is shown that such requirement is not fulfilled by the mean - field approach, nor by the statistical ensemble approach. further unusual features of the latter scheme are pointed out. | arxiv:1201.4237 |
the soft - core boson system is one of the simplest models of supersolids, which have both off - diagonal long - range order ( bose - einstein condensation ) and diagonal long - range order ( crystalline order ). although this model has been studied from various points of view, studies of the stability of current - flowing states are lacking. solving the gross - pitaevskii and bogoliubov equations, we obtain excitation spectra in superfluid, supersolid, and stripe phases. on the basis of the results of the excitation spectra, we present a stability phase diagram that shows the region of the metastable superflow states for each phase. | arxiv:1205.2126 |
soft supramolecular materials are promising for the design of innovative and highly tunable adhesives. these materials are composed of polymer chains functionalized by strongly interacting moieties, sometimes called " stickers ". in order to systematically investigate the effect of the presence of associative groups on the debonding properties of a supramolecular adhesive, a series of supramolecular model systems has been characterized by probe - tack tests. these model materials, composed of linear and low dispersity poly ( butylacrylate ) chains functionalized in the middle by a single tri - urea sticker, are able to self - associate by six hydrogen bonds and range in molecular weight ( m n ) between 5 and 85 kg / mol. the linear rheology and the nanostructure of the same materials ( called " pnba3u " ) was the object of a previous study 1, 2. at room temperature, the association of polymers via hydrogen bonds induces the formation of rod - like aggregates structured into bundles for m n \ textless { } 40kg / mol and the behavior of a soft elastic material was observed ( g ' \ textgreater { } \ textgreater { } g " and g ' ~ $ \ omega $ 0 ). for higher m n, the filaments were randomly oriented and polymers displayed a crossover towards viscous behavior although terminal relaxation was not reached in the experimental frequency window. all these materials show however similar adhesive properties characterized by a cohesive mode of failure and low debonding energies ( w adh \ textless { } 40j / m 2 for a debonding speed of 100 $ \ mu $ m / s ). the debonding mechanisms observed during the adhesion tests have been investigated in detail with an image tools analysis developed by our group 3. the measure of the projected area covered by cavities growing in the adhesive layer during debonding can be used to estimate the true stress in the walls of the cavities and thus, to characterize the in - situ large strain deformation of the thin layer during the adhesion test itself. this analysis revealed in particular that the pnba3u materials with m n \ textless { } 40 kg / mol soften very markedly at large deformation like yield stress fluids, explaining the low adhesion energies measured for these viscoelastic gels. 2 | arxiv:1609.04971 |
cross - lingual transfer is a leading technique for parsing low - resource languages in the absence of explicit supervision. simple ` direct transfer ' of a learned model based on a multilingual input encoding has provided a strong benchmark. this paper presents a method for unsupervised cross - lingual transfer that improves over direct transfer systems by using their output as implicit supervision as part of self - training on unlabelled text in the target language. the method assumes minimal resources and provides maximal flexibility by ( a ) accepting any pre - trained arc - factored dependency parser ; ( b ) assuming no access to source language data ; ( c ) supporting both projective and non - projective parsing ; and ( d ) supporting multi - source transfer. with english as the source language, we show significant improvements over state - of - the - art transfer models on both distant and nearby languages, despite our conceptually simpler approach. we provide analyses of the choice of source languages for multi - source transfer, and the advantage of non - projective parsing. our code is available online. | arxiv:2101.11216 |
the behaviors of null geodesics in the spherical symmetric black holes in einstein - maxwell - dilaton ( emd ) theory with coupling function $ f ( \ phi ) = e ^ { - 2 \ alpha \ phi } $ are meticulously analyzed. we investigate the effects of coupling constant $ \ alpha $ on the effective potential of photon trajectories within three ranges, namely $ 0 < \ alpha < 1 $, $ \ alpha = 1 $ and $ \ alpha > 1 $. we find that the thicknesses of lensing and photon rings are smaller at larger $ \ alpha $ and fixed electric charge in the unit of mass $ q $, whereas they are larger at fixed $ \ alpha $ and larger $ q $. this behavior can be described by using the angular lyapunov exponent $ \ gamma $ in the vicinity of the critical curve. remarkably, the behaviors of photon trajectories are found to be more interesting when $ \ alpha > 1 $. namely, the radius of the black hole shadow $ r _ \ text { s } $ becomes to be smaller than the photon sphere radius $ r _ \ text { ph } $ when $ \ alpha > 1 $ and $ q > q ^ * $. moreover, $ r _ \ text { s } $ goes to zero as $ q $ saturates the extremal limit, beyond which the photon orbit becomes absent. furthermore, we construct the optical appearance of black holes surrounded by optically and geometrically thin accretion disk with three cases of gralla - lupsasca - marrone ( glm ) emission profile. our results indicate that the observed flux originating from the lensing and photon rings exhibits suppression as $ \ alpha $ increases, while it undergoes amplification with the increasing parameter $ q $. | arxiv:2310.04221 |
let $ f $ be a cuspidal eigenform of even weight and trivial nebentypus, let $ p $ be a prime not dividing the level of $ f $, and let $ \ rho _ f $ be the $ p $ - adic galois representation attached to $ f $. assume that the $ l $ - function attached to the symmetric cube of $ \ rho _ f $ vanishes to odd order at its central point. then under some mild hypotheses, and conditional on certain consequences of arthur ' s conjectures, we construct a nontrivial element in the bloch - - kato selmer group of an appropriate twist of the symmetric cube of $ \ rho _ f $, in accordance with the bloch - - kato conjectures. our technique is based on the method of skinner and urban. we construct a class in the appropriate selmer group by $ p $ - adically deforming eisenstein series for the exceptional group $ g _ 2 $ in a generically cuspidal family and then studying a lattice in the corresponding family of $ g _ 2 $ - galois representations. we also make a detailed study of the specific conjectures used and explain how one might try to prove them. | arxiv:2202.03585 |
the only place in the world where at this time standard model higgs bosons can be produced and detected is the tevatron at fermilab. in this contribution, the most recent results on the search for a low mass higgs boson are presented, using datasets of up to 1. 9 fb - 1. in the absence of signal, the combined tevatron cross section limit at a higgs boson mass of 115 gev is determined to be 6. 2 ( 4. 3 expected ) times the standard model ( sm ) expectation, at 95 % confidence level. the expected gain in sensitivity from the forthcoming larger dataset and improved analysis methods will likely make an exclusion or observation at low mass possible in the near future. | arxiv:0805.1248 |
we study the effects of local and distance interactions in the unidimensional contact process ( cp ). in the model, each site of a lattice is occupied by an individual, which can be healthy or infected. as in the standard cp, each infected individual spreads the disease to one of its first - neighbors with rate $ \ lambda $, and with unitary rate, it becomes healthy. however, in our model, an infected individual can transmit the disease to an individual at a distance $ \ ell $ apart. this step mimics a vector - mediated transmission. we observe the host - host interactions do not alter the critical exponents significantly in comparison to a process with only l \ ' evy - type interactions. our results confirm, numerically, early field - theoretic predictions. | arxiv:1901.09969 |
context. the mechanism of disk formation around fast - rotating be stars is not well understood. in particular, it is not clear which mechanisms operate, in addition to fast rotation, to produce the observed variable ejection of matter. the star achernar is a privileged laboratory to probe these additional mechanisms because it is close, presents b - be phase variations on timescales ranging from 6 yr to 15 yr, a companion star was discovered around it, and probably presents a polar wind or jet. aims. despite all these previous studies, the disk around achernar was never directly imaged. therefore we seek to produce an image of the photosphere and close environment of the star. methods. we used infrared long - baseline interferometry with the pionier / vlti instrument to produce reconstructed images of the photosphere and close environment of the star over four years of observations. to study the disk formation, we compared the observations and reconstructed images to previously computed models of both the stellar photosphere alone ( normal b phase ) and the star presenting a circumstellar disk ( be phase ). results. the observations taken in 2011 and 2012, during the quiescent phase of achernar, do not exhibit a disk at the detection limit of the instrument. in 2014, on the other hand, a disk was already formed and our reconstructed image reveals an extended h - band continuum excess flux. our results from interferometric imaging are also supported by several h - alpha line profiles showing that achernar started an emission - line phase sometime in the beginning of 2013. the analysis of our reconstructed images shows that the 2014 near - ir flux extends to 1. 7 - 2. 3 equatorial radii. our model - independent size estimation of the h - band continuum contribution is compatible with the presence of a circumstellar disk, which is in good agreement with predictions from be - disk models. | arxiv:1703.02839 |
gaussian process state space models ( gp - ssms ) are a non - parametric model class suitable to represent nonlinear dynamics. they become increasingly popular in data - driven modeling approaches, i. e. when no first - order physics - based models are available. although a gp - ssm produces well - behaved approximations and gains increasing popularity, the fundamental system dynamics are just sparsely researched. in this paper, we present stability results for the gp - ssm depending on selected covariance function employing a deterministic point of view as widely done in the literature. the focus is set on the squared exponential function which is one of the most used covariance functions for nonlinear regression. we start with calculations according to the equilibrium points of gp - ssm and continue with conditions for stability. | arxiv:1811.06646 |
we present a chemical kinetics model of the solid - phase chemical evolution of a comet, beginning with a long period of cold - storage in the oort cloud, followed by five orbits that bring the comet close to the sun. the chemical model is based on an earlier treatment that considered only the cold - storage phase, and which was based on the interstellar ice chemical kinetics model magickal. the comet is treated as 25 chemically distinct layers. updates to the previous model includes : ( i ) time - and depth - dependent temperature profiles according to heliocentric distance ; ( ii ) a rigorous treatment of back - diffusion for species capable of diffusing through the bulk - ice layers ; ( iii ) adoption of recent improvements in the kinetic treatment of nondiffusive chemical reaction rates. starting from an initially simple ice composition, interstellar uv photons drive a rapid chemistry in the upper micron of material, but diminished by absorption of the uv by the dust component. galactic cosmic rays ( gcrs ) drive a much slower chemistry in the deeper ices over the long cold - storage period down to 10 m. the first solar approach drives off the upper layers of ice material via thermal desorption and / or dissociation, bringing closer to the surface the deeper material that previously underwent long - term processing by gcrs. subsequent orbits are more uniform in their chemical behavior. loss of molecular material leads to concentration of the dust in the upper layers. substantial quantities of complex organic molecules are formed in the upper 10 m during the cold storage phase, with some of this material released during solar approach ; however, their abundances with respect to water appear too low to account for the observed gas - phase values for comet hale - bopp, indicating that the majority of complex molecular material observed, at least in comet hale - bopp, is an inheritance of primordial material. | arxiv:2408.15509 |
tydi is an open specification for streaming dataflow designs in digital circuits, allowing designers to express how composite and variable - length data structures are transferred over streams using clear, data - centric types. these data types are extensively used in a many application domains, such as big data and sql applications. this way, tydi provides a higher - level method for defining interfaces between components as opposed to existing bit and byte - based interface specifications. in this paper, we introduce an open - source intermediate representation ( ir ) which allows for the declaration of tydi ' s types. the ir enables creating and connecting components with tydi streams as interfaces, called streamlets. it also lets backends for synthesis and simulation retain high - level information, such as documentation. types and streamlets can be easily reused between multiple projects, and tydi ' s streams and type hierarchy can be used to define interface contracts, which aid collaboration when designing a larger system. the ir codifies the rules and properties established in the tydi specification and serves to complement computation - oriented hardware design tools with a data - centric view on interfaces. to support different backends and targets, the ir is focused on expressing interfaces, and complements behavior described by hardware description languages and other irs. additionally, a testing syntax for the verification of inputs and outputs against abstract streams of data, and for substituting interdependent components, is presented which allows for the specification of behavior. to demonstrate this ir, we have created a grammar, parser, and query system, and paired these with a backend targeting vhdl. | arxiv:2308.13436 |
quantum systems with a finite number of states at all times have been a primary element of many physical models in nuclear and elementary particle physics, as well as in condensed matter physics. today, however, due to a practical demand in the area of developing quantum technologies, a whole set of novel tasks for improving our understanding of the structure of finite - dimensional quantum systems has appeared. in the present article we will concentrate on one aspect of such studies related to the problem of explicit parameterization of state space of an $ n $ - level quantum system. more precisely, we will discuss the problem of a practical description of the unitary $ su ( n ) $ - invariant counterpart of the $ n $ - level state space $ \ mathfrak { p } _ n $, i. e., the unitary orbit space $ \ mathfrak { p } _ n / su ( n ) $. it will be demonstrated that the combination of well - known methods of the polynomial invariant theory and convex geometry provides useful parameterization for the elements of $ \ mathfrak { p } _ n / su ( n ) $. to illustrate the general situation, a detailed description of $ \ mathfrak { p } _ n / su ( n ) $ for low - level systems : qubit $ ( n = 2 ) \,, $ qutrit $ ( n = 3 ) \,, $ quatrit $ ( n = 4 ) \, $ - will be given. | arxiv:2108.12499 |
population dynamics of a competitive two - species system under the influence of random events are analyzed and expressions for the steady - state population mean, fluctuations, and cross - correlation of the two species are presented. it is shown that random events cause the population mean of each specie to make smooth transition from far above to far below of its growth rate threshold. at the same time, the population mean of the weaker specie never reaches the extinction point. it is also shown that, as a result of competition, the relative population fluctuations do not die out as the growth rates of both species are raised far above their respective thresholds. this behavior is most remarkable at the maximum competition point where the weaker specie ' s population statistics becomes completely chaotic regardless of how far its growth rate in raised. | arxiv:2002.07307 |
selecting high - quality candidates from large datasets is critical in applications such as drug discovery, precision medicine, and alignment of large language models ( llms ). while conformal selection ( cs ) provides rigorous uncertainty quantification, it is limited to univariate responses and scalar criteria. to address this issue, we propose multivariate conformal selection ( mcs ), a generalization of cs designed for multivariate response settings. our method introduces regional monotonicity and employs multivariate nonconformity scores to construct conformal p - values, enabling finite - sample false discovery rate ( fdr ) control. we present two variants : mcs - dist, using distance - based scores, and mcs - learn, which learns optimal scores via differentiable optimization. experiments on simulated and real - world datasets demonstrate that mcs significantly improves selection power while maintaining fdr control, establishing it as a robust framework for multivariate selection tasks. | arxiv:2505.00917 |
a coordinate cone in r ^ n is an intersection of some coordinate hyperplanes and open coordinate half - spaces. a semi - monotone set is a defnable in an o - minimal structure over the reals, open bounded subset of r ^ n such that its intersection with any translation of any coordinate cone is connected. this can be viewed as a generalization of the convexity property. semi - monotone sets have a number of interesting geometric and combinatorial properties. the main result of the paper is that every semi - monotone set is a topological regular cell. | arxiv:1004.5047 |
existing reconstruction models in snapshot compressive imaging systems ( sci ) are trained with a single well - calibrated hardware instance, making their performance vulnerable to hardware shifts and limited in adapting to multiple hardware configurations. to facilitate cross - hardware learning, previous efforts attempt to directly collect multi - hardware data and perform centralized training, which is impractical due to severe user data privacy concerns and hardware heterogeneity across different platforms / institutions. in this study, we explicitly consider data privacy and heterogeneity in cooperatively optimizing sci systems by proposing a federated hardware - prompt learning ( fedhp ) framework. rather than mitigating the client drift by rectifying the gradients, which only takes effect on the learning manifold but fails to solve the heterogeneity rooted in the input data space, fedhp learns a hardware - conditioned prompter to align inconsistent data distribution across clients, serving as an indicator of the data inconsistency among different hardware ( e. g., coded apertures ). extensive experimental results demonstrate that the proposed fedhp coordinates the pre - trained model to multiple hardware configurations, outperforming prevalent fl frameworks for 0. 35db under challenging heterogeneous settings. moreover, a snapshot spectral heterogeneous dataset has been built upon multiple practical sci systems. data and code are aveilable at https : / / github. com / jiamian - wang / fedhp - snapshot - compressive - imaging | arxiv:2306.01176 |
recently, we introduced the " newman - penrose map, " a novel correspondence between a certain class of solutions of einstein ' s equations and self - dual solutions of the vacuum maxwell equations, which we showed was closely related to the classical double copy. here, we give an alternative definition of this correspondence in terms of quantities that are defined naturally on twistor space, and a shear - free null geodesic congruence on minkowski space whose twistorial character is articulated by the kerr theorem. the advantage of this reformulation is that it is purely geometrical in nature, being manifestly invariant under both spacetime diffeomorphisms and projective transformations on twistor space. while the original formulation of the map may be more convenient for most explicit calculations, the twistorial formulation we present here may be of greater theoretical utility. | arxiv:2104.09525 |
we present a general construction of a geometric notion of circuit complexity for gaussian states ( both bosonic and fermionic ) in terms of riemannian geometry. we lay out general conditions that a riemannian metric function on the space of gaussian states should satisfy in order for it to yield a physically reasonable measure of complexity. this general formalism can naturally accommodate modifications to complexity geometries that arise from cost functions that depend nontrivially on the instantaneous state and on the direction on circuit space at each point. we explore these modifications and, as a particular case, we show how to account for time - reversal symmetry breaking in measures of complexity, which is often natural from an experimental ( and thermodynamical ) perspective, but is absent in commonly studied complexity measures. this establishes a first step towards building a quantitative, geometric notion of complexity that faithfully mimics what is experienced as " easy " or " hard " to implement in a lab from a physically motivated point of view. | arxiv:2309.14418 |
most models for weakly supervised video anomaly detection ( ws - vad ) rely on multiple instance learning, aiming to distinguish normal and abnormal snippets without specifying the type of anomaly. however, the ambiguous nature of anomaly definitions across contexts may introduce inaccuracy in discriminating abnormal and normal events. to show the model what is anomalous, a novel framework is proposed to guide the learning of suspected anomalies from event prompts. given a textual prompt dictionary of potential anomaly events and the captions generated from anomaly videos, the semantic anomaly similarity between them could be calculated to identify the suspected events for each video snippet. it enables a new multi - prompt learning process to constrain the visual - semantic features across all videos, as well as provides a new way to label pseudo anomalies for self - training. to demonstrate its effectiveness, comprehensive experiments and detailed ablation studies are conducted on four datasets, namely xd - violence, ucf - crime, tad, and shanghaitech. our proposed model outperforms most state - of - the - art methods in terms of ap or auc ( 86. 5 \ %, \ hl { 90. 4 } \ %, 94. 4 \ %, and 97. 4 \ % ). furthermore, it shows promising performance in open - set and cross - dataset cases. the data, code, and models can be found at : \ url { https : / / github. com / shiwoaz / lap }. | arxiv:2403.01169 |
objective kalman filtering has previously been applied to track neural model states and parameters, particularly at the scale relevant to eeg. however, this approach lacks a reliable method to determine the initial filter conditions and assumes that the distribution of states remains gaussian. this study presents an alternative, data - driven method to track the states and parameters of neural mass models ( nmms ) from eeg recordings using deep learning techniques, specifically an lstm neural network. approach an lstm filter was trained on simulated eeg data generated by a neural mass model using a wide range of parameters. with an appropriately customised loss function, the lstm filter can learn the behaviour of nmms. as a result, it can output the state vector and parameters of nmms given observation data as the input. main results test results using simulated data yielded correlations with r squared of around 0. 99 and verified that the method is robust to noise and can be more accurate than a nonlinear kalman filter when the initial conditions of the kalman filter are not accurate. as an example of real - world application, the lstm filter was also applied to real eeg data that included epileptic seizures, and revealed changes in connectivity strength parameters at the beginnings of seizures. significance tracking the state vector and parameters of mathematical brain models is of great importance in the area of brain modelling, monitoring, imaging and control. this approach has no need to specify the initial state vector and parameters, which is very difficult to do in practice because many of the variables being estimated cannot be measured directly in physiological experiments. this method may be applied using any neural mass model and, therefore, provides a general, novel, efficient approach to estimate brain model variables that are often difficult to measure. | arxiv:2301.08391 |
we introduce a new convexified matching method for missing value imputation and individualized inference inspired by computational optimal transport. our method integrates favorable features from mainstream imputation approaches : optimal matching, regression imputation, and synthetic control. we impute counterfactual outcomes based on convex combinations of observed outcomes, defined based on an optimal coupling between the treated and control data sets. the optimal coupling problem is considered a convex relaxation to the combinatorial optimal matching problem. we estimate granular - level individual treatment effects while maintaining a desirable aggregate - level summary by properly constraining the coupling. we construct transparent, individual confidence intervals for the estimated counterfactual outcomes. we devise fast iterative entropic - regularized algorithms to solve the optimal coupling problem that scales favorably when the number of units to match is large. entropic regularization plays a crucial role in both inference and computation ; it helps control the width of the individual confidence intervals and design fast optimization algorithms. | arxiv:2407.05372 |
it is customary to expect from a logical system that it can be algebraizable, in the sense that an algebraic companion of the deductive machinery can always be found. since the inception of da costa ' s paraconsistent calculi $ c _ n $, algebraic equivalents for such systems have been sought. it is known, however, that these systems are not self - extensional ( i. e., they do not satisfy the replacement property ). more than this, they are not algebraizable in the sense of blok - pigozzi. the same negative results hold for several systems of the hierarchy of paraconsistent logics known as logics of formal inconsistency ( lfis ). because of this, several systems belonging to this class of logics are only characterizable by semantics of a non - deterministic nature. this paper offers a solution for two open problems in the domain of paraconsistency, in particular connected to algebraization of lfis, by extending with rules several lfis weaker than $ c _ 1 $, thus obtaining the replacement property ( that is, such lfis turn out to be self - extensional ). moreover, these logics become algebraizable in the standard lindenbaum - tarski ' s sense by a suitable variety of boolean algebras extended with additional operations. the weakest lfi satisfying replacement presented here is called rmbc, which is obtained from the basic lfi called mbc. some axiomatic extensions of rmbc are also studied. in addition, a neighborhood semantics is defined for such systems. it is shown that rmbc can be defined within the minimal bimodal non - normal logic e + e defined by the fusion of the non - normal modal logic e with itself. finally, the framework is extended to first - order languages. rqmbc, the quantified extension of rmbc, is shown to be sound and complete w. r. t. the proposed algebraic semantics. | arxiv:2003.09522 |
with a view to exploring a new kind of phase transition in the process of hadronization of quark - gluon plasma ( qgp ) we investigate the occurrence of pentaquark baryons and tetraquark mesons in the system. for this purpose, the frame work of an analoguous saha ' s ionization formula for the colored ions in the system is used. the study of color - ionic - fraction ( cif ) of multiply ( color ) ionized to unionized quark clusters ( termed as " quarkons " ) as a function of temperature is carried out. it is pointed out that not only the temperature of the fire - ball in the relativistic heavy ion collisions evolves with respect to space and time but also the cif associated with a particular stage of ionization. further, for the case of single color - ionization a correspondence of the present results with those available for the bubble nucleation mechanism in qgp is demonstrated. | arxiv:hep-ph/0507054 |
motivated by an application in community detection, we consider an \ er random graph conditioned on the rare event that all connected components are fully connected. such graphs can be considered as partitions of vertices into cliques. hence, this conditional distribution defines a distribution over partitions. we show that a popular community detection method is equivalent to bayesian inference with this distribution as prior over the community partitions. using tools from analytic combinatorics, we prove limit theorems for several graph observables in this conditional distribution : the number of cliques ; the number of edges ; and the degree distribution. we consider several regimes of the connection probability $ p $ as the number of vertices $ n $ diverges. for $ p = \ tfrac { 1 } { 2 } $, the conditioning yields the uniform distribution over set partitions, which is well - studied, but has not been studied as a graph distribution before. for $ p < \ tfrac { 1 } { 2 } $, we show that the number of cliques is of the order $ n / \ sqrt { \ log n } $, while for $ p > \ tfrac { 1 } { 2 } $, we prove that the graph consists of a single clique with high probability. this shows that there is a phase transition at $ p = \ tfrac { 1 } { 2 } $. we additionally study the near - critical regime $ p _ n \ downarrow \ tfrac { 1 } { 2 } $, as well as the sparse regime $ p _ n \ downarrow0 $. finally, we discuss the implications of these results for community detection. | arxiv:2405.13454 |
we present a heuristic algorithm for solving the problem of scheduling plans of tasks. the plans are ordered vectors of tasks, and tasks are basic operations carried out by resources. plans are tied by temporal, precedence and resource constraints that makes the scheduling problem hard to solve in polynomial time. the proposed heuristic, that has a polynomial worst - case time complexity, searches for a feasible schedule that maximize the number of plans scheduled, along a fixed time window, with respect to temporal, precedence and resource constraints. | arxiv:2102.03555 |
we present a proper off - mass - shell extension of the chiral reduction formula ( chrf ) proposed by yamagishi and zaned. this is achieved by rewriting the chrf in a manifestly consistent form with the conventional lsz reduction formula. | arxiv:hep-ph/0412281 |
cosmological simulations suggest that most of the matter in the universe is distributed along filaments connecting galaxies. illuminated by the cosmic uv background ( uvb ), these structures are expected to glow in fluorescent lyman alpha emission with a surface brightness ( sb ) that is well below current observational limits for individual detections. here, we perform a stacking analysis of the deepest muse / vlt data using three - dimensional regions ( subcubes ) with orientations determined by the position of neighbouring lyman alpha galaxies ( laes ) at 3 < z < 4. our method should increase the probability of detecting filamentary lyman alpha emission, provided that these structures are lyman limit systems ( llss ). by stacking 390 oriented subcubes we reach a 2 sigma sensitivity level of sb ~ 0. 44e - 20 erg / s / cm ^ 2 / arcsec ^ 2 in an aperture of 1 arcsec ^ 2 x 6. 25 angstrom, which is three times below the expected fluorescent lyman alpha signal from the haardt - madau 2012 ( hm12 ) uvb at z ~ 3. 5. no detectable emission is found on intergalactic scales, implying that at least two thirds of our subcubes do not contain oriented llss for a hm12 uvb. on the other hand, significant emission is detected in the circum - galactic medium ( cgm ) of galaxies in the direction of the neighbours. the signal is stronger for galaxies with a larger number of neighbours and appears to be independent of any other galaxy properties such as luminosity, redshift and neighbour distance. we estimate that preferentially oriented satellite galaxies cannot contribute significantly to this signal, suggesting instead that gas densities in the cgm are typically larger in the direction of neighbouring galaxies on cosmological scales. | arxiv:1706.03785 |
based on the previously suggested model of nanoscale dislocations induced josephson junctions and their arrays, we study the magnetic field induced electric polarization effects in intrinsically granular superconductors. in addition to a new phenomenon of chemomagnetoelectricity, the model predicts also a few other interesting effects, including charge analogues of meissner paramagnetism ( at low fields ) and " fishtail " anomaly ( at high fields ). the conditions under which these effects can be experimentally measured in non - stoichiometric high - t _ c superconductors are discussed. | arxiv:cond-mat/0506160 |
tensor network states are used extensively as a mathematically convenient description of physically relevant states of many - body quantum systems. those built on regular lattices, i. e. matrix product states ( mps ) in dimension 1 and projected entangled pair states ( peps ) in dimension 2 or higher, are of particular interest in condensed matter physics. the general goal of this work is to characterize which features of mps and peps are generic and which are, on the contrary, exceptional. this problem can be rephrased as follows : given an mps or peps sampled at random, what are the features that it displays with either high or low probability? one property which we are particularly interested in is that of having either rapidly decaying or long - range correlations. in a nutshell, our main result is that translation - invariant mps and peps typically exhibit exponential decay of correlations at a high rate. we have two distinct ways of getting to this conclusion, depending on the dimensional regime under consideration. both yield intermediate results which are of independent interest, namely : the parent hamiltonian and the transfer operator of such mps and peps typically have a large spectral gap. in all these statements, our aim is to get a quantitative estimate of the considered quantity ( generic correlation length or spectral gap ), which has the best possible dependency on the physical and bond dimensions of the random mps or peps. | arxiv:1906.11682 |
undoubtedly, social media are brainstormed by a tremendous volume of stories, feedback, reviews, and reactions expressed in various languages and idioms, even though some are factually incorrect. these motifs make assessing such data challenging, time - consuming, and vulnerable to misinterpretation. this paper describes a classification model for movie reviews founded on deep learning approaches. almost 500kb pairs of balanced data from the imdb movie review databases are employed to train the model. people ' s perspectives regarding movies were classified using both the long short - term memory ( lstm ) and convolutional neural network ( cnn ) strategies. according to the findings, the cnn algorithm ' s prediction accuracy rate would be almost 97. 4 %. furthermore, the model trained by lstm resulted in accuracies of around and applying 99. 2 % within the keras library. the model is investigated more by modification of model parameters. according to the outcomes, ltsm outperforms cnn in assessing imdb movie reviews and is computationally less costly than lstm. | arxiv:2210.10726 |
we discuss the possibility of intermediate gauge coupling unification in unified models of string origin. useful relations of the \ beta - function coefficients are derived, which ensure unification of couplings when kaluza - - klein excitations are included above the compactification scale. we apply this procedure to two models with su ( 3 ) \ times su ( 3 ) _ l \ times su ( 3 ) _ r and su ( 4 ) \ times o ( 4 ) gauge symmetries. | arxiv:hep-ph/9908462 |
for gradient flows of energies, both spectral renormalization ( srn ) and energy landscape ( el ) techniques have been used to establish slow motion of orbits near low - energy manifold. we show that both methods are applicable to flows induced by families of gradients and compare the scope and specificity of the results. the srn techniques capture the flow in a thinner neighborhood of the manifold, affording a leading order representation of the slow flow via as projection of the flow onto the tangent plane of the manifold. the srn approach requires a spectral gap in the linearization of the full gradient flow about the points on the low - energy manifold. we provide conditions on the choice of gradient under which the spectral gap is preserved, and show that up to reparameterization the slow flow is invariant under these choices of gradients. the el methods estimate the magnitude of the slow flow, but cannot capture its leading order form. however the el only requires normal coercivity for the second variation of the energy, and does not require spectral conditions on the linearization of the full flow. it thus applies to a much larger class of gradients of a given energy. we develop conditions under which the assumptions of the srn method imply the applicability of the el method, and identify a large family of gradients for which the el methods apply. in particular we apply both approaches to derive the interaction of multi - pulse solutions within the 1 + 1d functionalized cahn - hilliard ( fch ) gradient flow, deriving gradient invariance for a class of gradients arising from powers of a homogeneous differential operator. | arxiv:2001.00395 |
benefiting from both molecular tunability and versatile methods for deployment, optically interfaced molecular spins are a promising platform for quantum technologies such as sensing and imaging. room - temperature optically detected coherent spin control is a key enabler for many applications, combining sensitive readout, versatile spin manipulation, and ambient operation. here we demonstrate such functionality in a molecular spin system. using the photoexcited triplet state of organic chromophores ( pentacene doped in a para - terphenyl host ), we optically detect coherent spin manipulation with photoluminescence contrasts exceeding 10 % and microsecond coherence times at room temperature. we further demonstrate how coherent control of multiple triplet sublevels can significantly enhance optical spin contrast, and extend optically detected coherent control to a thermally evaporated thin film, retaining high photoluminescence contrast and coherence times of order one microsecond. these results open opportunities for room - temperature quantum technologies that can be systematically tailored through synthetic chemistry. | arxiv:2402.07572 |
by direct measurements of the gas temperature, the atacama large millimeter / sub - millimeter array ( alma ) has yielded a new diagnostic tool to study the solar chromosphere. here we present an overview of the brightness - temperature fluctuations from several high - quality and high - temporal - resolution ( i. e., 1 and 2 sec cadence ) time series of images obtained during the first two years of solar observations with alma, in band 3 and band 6, centred at around 3 mm ( 100 ghz ) and 1. 25 mm ( 239 ghz ), respectively. the various datasets represent solar regions with different levels of magnetic flux. we perform fast fourier and lomb - scargle transforms to measure both the spatial structuring of dominant frequencies and the average global frequency distributions of the oscillations ( i. e., averaged over the entire field of view ). we find that the observed frequencies significantly vary from one dataset to another, which is discussed in terms of the solar regions captured by the observations ( i. e., linked to their underlying magnetic topology ). while the presence of enhanced power within the frequency range 3 - 5 mhz is found for the most magnetically quiescent datasets, lower frequencies dominate when there is significant influence from strong underlying magnetic field concentrations ( present inside and / or in the immediate vicinity of the observed field of view ). we discuss here a number of reasons which could possibly contribute to the power suppression at around 5. 5 mhz in the alma observations. however, it remains unclear how other chromospheric diagnostics ( with an exception of halpha line - core intensity ) are unaffected by similar effects, i. e., they show very pronounced 3 - min oscillations dominating the dynamics of the chromosphere, whereas only a very small fraction of all the pixels in the ten alma data sets analysed here show peak power near 5. 5 mhz. | arxiv:2010.01918 |
we study the non - equilibrium dynamics of kicked ising models in $ 1 + 1 $ dimensions which have interactions alternating between odd and even bonds in time. these models can be understood as quantum circuits tiling space - time with the generalized space - time dual properties of tri - unitarity ( three " arrows of time " ) at the global level, and also second - level dual - unitarity at the local level, which constrains the behavior of pairs of local gates underlying the circuit under a space - time rotation. we identify a broad class of initial product states wherein the effect of the environment on a small subsystem can be exactly represented by influence matrices with simple markovian structures, resulting in the subsystem ' s full dynamics being efficiently computable. we further find additional conditions under which the dynamics of entanglement can be solved for all times, yielding rich phenomenology ranging from linear growth at half the maximal speed allowed by locality, followed by saturation to maximum entropy ( i. e., thermalization to infinite temperature ) ; to entanglement growth with saturation to extensive but sub - maximal entropy. intriguingly, for certain parameter regimes, we find a nonchaotic class of dynamics which is neither integrable nor clifford, exemplified by nonzero operator entanglement growth but with a spectral form factor which exhibits large, apparently time - quasiperiodic revivals. | arxiv:2312.12239 |
we present the results of an experiment documenting racial bias on meta ' s advertising platform in brazil and the united states. we find that darker skin complexions are penalized, leading to real economic consequences. for every \ $ 1, 000 an advertiser spends on ads with models with light - skin complexions, that advertiser would have to spend \ $ 1, 159 to achieve the same level of engagement using photos of darker skin complexion models. meta ' s budget optimization tool reinforces these viewer biases. when pictures of models with light and dark complexions are allocated a shared budget, meta funnels roughly 64 \ % of the budget towards photos featuring lighter skin complexions. | arxiv:2412.14307 |
in this talk i introduce the critical behavior occurring at the extremal limit of black holes. the extremal limit of black holes is a critical point and a phase transition takes place from the extremal black holes to their nonextremal counterparts. some critical exponents satisfying the scaling laws are obtained. from the scaling laws we introduce the concept of the effective dimension of black holes and discuss the relationship between the critical behavior and the statistical interpretation of black hole entropy. | arxiv:gr-qc/9901026 |
some recently discovered short - period earth to neptune sized exoplanets ( super earths ) have low observed mean densities which can only be explained by voluminous gaseous atmospheres. here, we study the conditions allowing the accretion and retention of such atmospheres. we self - consistently couple the nebular gas accretion onto rocky cores and the subsequent evolution of gas envelopes following the dispersal of the protoplanetary disk. specifically, we address mass - loss due to both photo - evaporation and cooling of the planet. we find that planets shed their outer layers ( dozens of percents in mass ) following the disk ' s dispersal ( even without photo - evaporation ), and their atmospheres shrink in a few myr to a thickness comparable to the radius of the underlying rocky core. at this stage, atmospheres containing less particles than the core ( equivalently, lighter than a few % of the planet ' s mass ) can be blown away by heat coming from the cooling core, while heavier atmospheres cool and contract on a timescale of gyr at most. by relating the mass - loss timescale to the accretion time, we analytically identify a goldilocks region in the mass - temperature plane in which low - density super earths can be found : planets have to be massive and cold enough to accrete and retain their atmospheres, while not too massive or cold, such that they do not enter runaway accretion and become gas giants ( jupiters ). we compare our results to the observed super - earth population and find that low - density planets are indeed concentrated in the theoretically allowed region. our analytical and intuitive model can be used to investigate possible super - earth formation scenarios. | arxiv:1512.07925 |
we examine the vacuum polarization contribution in the renormalization scheme of qed. normally, the quadratic divergence term is discarded under the condition that the counter term of the lagrangian density should be gauge invariant. here, it is shown that the whole contribution of the photon self - energy should not be considered for the renormalization procedure. in fact, the finite contribution of the renormalization in the vacuum polarization is shown to give rise to the hyperfine splitting energy which disagrees with the experimental observation in hydrogen atom. for the treatment of the vacuum polarization, we present a new renormalization scheme of the photon self - energy diagram. | arxiv:0901.3421 |
a moving dielectric medium can displace the optical path of light passing through it, a phenomenon known as the fresnel - fizeau optical drag effect. the resulting displacement is proportional to the medium ' s velocity. in this article, we report on an anomalous optical drag effect, where the displacement is still proportional to the medium ' s speed but along the direction opposite to the medium ' s movement. we conduct an optical drag experiment under conditions of electromagnetically - induced transparency and observe the transition from normal, to null, to anomalous optical drag by modification of the two - photon detuning. | arxiv:2109.02534 |
this paper proposes a reconfigurable bidirectional array antenna with high - efficiency radiations and flexible beam - switching capability by employing a novel transmit - reflect switchable metasurface ( trsm ). to realize the electromagnetic ( em ) wave transmitted or reflected manipulation, a dedicated transmit - reflect switch layer ( trsl ) with periodically soldered pin diodes is introduced between two transmitted metasurfaces. by switching on / off the embedded diodes, the trsl performs as a mesh - type ground layer or polarization - grid layer, exhibiting a reflect or transmit property to the incident wave respectively. further, utilizing the above trsm configuration in conjunction with a microstrip feed antenna, bidirectional radiations are obtained at the same frequency and polarization. to further reduce the number of pin diodes and control complexity, an enhanced trsm using a single diode to control two unit cells is also investigated, resulting in half pin diodes reduction. since the bidirectional beam - switching is achieved by only controlling pin diodes integrated in the ground plane instead of directly acting on the radiation element, which reduces insertion loss and avoids phase quantization errors, the proposed antenna can maintain a high aperture efficiency. to verify this concept, a prototype was designed, fabricated, and measured, demonstrating a successful realization of backward and forward patterns with peak gains of 22. 3 and 22. 1 dbi, and aperture efficiencies of 47. 2 % and 43. 8 %. the 3 - db gain bandwidths of reflected and transmitted modes are 13. 7 % and 12. 3 %. this antenna has the advantages of high gain, high aperture efficiency, simple configuration, cost - effectiveness, and flexible and digital beam control. | arxiv:2505.08556 |
we fabricated fete0. 5se0. 5 superconducting wires using ex - situ powder - in - tube method with an fe sheath. it was amazing that superconducting current was observed in the as - drawn wire without any heat treatments. by heat treatment at 200c for 2 hours, tczero and jc at 4. 2 k were enhanced up to 9. 1 k and 64. 1 a / cm2 ( ic = 182. 6 ma ), respectively. furthermore, the jc of fete0. 5se0. 5 wire heat treated at 200c for 2 hours was not much sensitive to the applied magnetic fields. therefore, fete0. 5se0. 5 wires have a great potential for applications. | arxiv:1012.1404 |
this paper introduces a novel statistical simulator designed to model propagation in two - way diffuse power ( twdp ) fading channels. the simulator employs two zero - mean stochastic sinusoids to simulate specular components, while a sum of sinusoids is used to model the diffuse one. using the developed simulator, the autocorrelation and cross - correlation functions of the quadrature components, as well as the autocorrelation of the complex and squared envelope, are derived for the first time in literature for channels experiencing twdp fading. the statistical properties of the proposed simulator are thoroughly validated through extensive simulations, which closely align with the theoretical results. | arxiv:2502.03388 |
we study an su ( n ) gauge - higgs model with n _ f massless fundamental fermions on m ^ 3 \ otimes s ^ 1. the model has two kinds of order parameters for gauge symmetry breaking : the component gauge field for the s ^ 1 direction ( hosotani mechanism ) and the higgs field ( higgs mechanism ). we find that the model possesses three phases called hosotani, higgs and coexisting phases for n = odd, while for n = even, the model has only two phases, the hosotani and coexisting phases. the phase structure depends on a parameter of the model and the size of the extra dimension. the critical radius and the order of the phase transition are determined. we also consider the case that the representation of matter fields under the gauge group is changed. we find some models, in which there is only one phase, independent of parameters of the models as well as the size of the extra dimension. | arxiv:hep-th/0305213 |
local solutions of riemann problems for quadratic systems of two conservation laws were constructed in the geometric context. in this paper, also for quadratic systems, we decompose the characteristic and sonic ' surfaces in their slow and fast components. these decompositions allow to decompose the wave manifold in regions called admissible region and non admissible region. there are admissible regions having local shock curve arcs and non local shock curve arcs. such regions are important to construct non local solutions of riemann problems. our study is restricted to the symmetric case iv in the sheaffer - shearer classification. | arxiv:1908.01870 |
in this paper, by employing the $ k _ { t } $ factorization theorem, we calculate firstly the next - to - leading - order ( nlo ) twist - 3 contributions to the pion electromagnetic form factors in the $ \ pi \ gamma ^ * \ to \ pi $ process. from the analytical and numerical calculations we find the following points : ( a ) for the leading order ( lo ) twist - 2, twist - 3 and the nlo twist - 2 contributions, our results agree very well with those obtained in previous works ; ( b ) we extract out two factors $ f ^ { ( 1 ) } _ { \ rm t3 } ( x _ i, t, q ^ 2 ) $ and $ \ ov { f } ^ { ( 1 ) } _ { \ rm t3 } ( x _ i, t, q ^ 2 ) $, which describe directly the nlo twist - 3 contributions to the pion electromagnetic form factors $ f ^ + ( q ^ 2 ) $ ; ( c ) the nlo twist - 3 contribution is negative in sign and cancel partially with the nlo twist - 2 part, the total nlo contribution can therefore provide a roughly $ \ pm 20 \ % $ corrections to the total lo contribution in the considered ranges of $ q ^ 2 $ ; and ( d ) the theoretical predictions for $ q ^ 2 f ^ + ( q ^ 2 ) $ in the low - $ q ^ 2 $ region agree well with currently available data, this agreement can be improved by the inclusion of the nlo contributions. | arxiv:1401.5118 |
we introduce harper, a novel dataset for 3d body pose estimation and forecast in dyadic interactions between users and spot, the quadruped robot manufactured by boston dynamics. the key - novelty is the focus on the robot ' s perspective, i. e., on the data captured by the robot ' s sensors. these make 3d body pose analysis challenging because being close to the ground captures humans only partially. the scenario underlying harper includes 15 actions, of which 10 involve physical contact between the robot and users. the corpus contains not only the recordings of the built - in stereo cameras of spot, but also those of a 6 - camera optitrack system ( all recordings are synchronized ). this leads to ground - truth skeletal representations with a precision lower than a millimeter. in addition, the corpus includes reproducible benchmarks on 3d human pose estimation, human pose forecasting, and collision prediction, all based on publicly available baseline approaches. this enables future harper users to rigorously compare their results with those we provide in this work. | arxiv:2403.14447 |
we revisit the integrability of quantum circuits constructed from two - qubit unitary gates $ u $ that satisfy the yang - baxter equation. a brickwork arrangement of $ u $ typically corresponds to an integrable trotterization of some hamiltonian dynamics. here, we consider more general circuit geometries which include circuits without any nontrivial space periodicity. we show that any time - periodic quantum circuit in which $ u $ is applied to each pair of neighbouring qubits exactly once per period remains integrable. we further generalize this framework to circuits with time - varying two - qubit gates. the spatial arrangement of gates in the integrable circuits considered herein can break the space - reflection symmetry even when $ u $ itself is symmetric. by analyzing the dynamical spin susceptibility on ballistic hydrodynamic scale, we investigate how an asymmetric arrangement of gates affects the spin transport. while it induces nonzero higher odd moments in the dynamical spin susceptibility, the first moment, which corresponds to a drift in the spreading of correlations, remains zero. we explain this within a quasiparticle picture which suggests that a nonzero drift necessitates gates acting on distinct degrees of freedom. | arxiv:2503.04673 |
in this paper, we consider the small viscosity limit problem for the isentropic compressible navier - stokes equations in a 2d exterior domain with impermeable boundary conditions, and the corresponding euler equations have vortex sheet solutions. we obtain that away from the boundary and the contact discontinuous the isentropic compressible viscous flow can be approximated by the corresponding inviscid flow, near the boundary ( the contact discontinuous ) there is a boundary layer ( vortex layer ) for the angular velocity in the leading order expansion of solution, while the radial velocity and the pressure do not have boundary layers ( vortex layers ) in the leading order. we rigorously justify the asymptotic behavior of solutions in the $ l ^ { \ infty } $ space for the small viscosities limit in the lagrangian coordinates. | arxiv:1906.10599 |
despite impressive progress in areas like mathematical reasoning, large language models still face significant challenges in consistently solving complex problems. drawing inspiration from key human learning strategies, we propose two novel strategies to enhance the capability of large language models to solve these complex problems. first, adaptive difficulty curriculum learning ( adcl ) is a novel curriculum learning strategy that tackles the difficulty shift phenomenon ( i. e., a model ' s perception of problem difficulty dynamically changes during training ) by periodically re - estimating difficulty within upcoming data batches to maintain alignment with the model ' s evolving capabilities. second, expert - guided self - reformulation ( egsr ) is a novel reinforcement learning strategy that bridges the gap between imitation learning and pure exploration by guiding models to reformulate expert solutions within their own conceptual framework, rather than relying on direct imitation, fostering deeper understanding and knowledge assimilation. extensive experiments on challenging mathematical reasoning benchmarks, using qwen2. 5 - 7b as the base model, demonstrate that these human - inspired strategies synergistically and significantly enhance performance. notably, their combined application improves performance over the standard zero - rl baseline by 10 % on the aime24 benchmark and 16. 6 % on aime25. | arxiv:2505.08364 |
the languages of logics based on team semantics typically only allow atomic negation or restricted negation. in this paper, we explore propositional team - based logics with full ( intuitionistic ) negation. we demonstrate that including full intutionistic negation does not complicate the axiomatization of propositional team - based logics with the downward closure property. we also review known expressive completeness results for these logics, highlighting how relevant complemented properties are expressed in propositional dependence logic without directly using negation. building on these insights, we also prove a new result : propositional logic extended with both dependence and inclusion atoms is expressively complete. | arxiv:2410.08413 |
generalized density dependence in skyrme effective interactions is investigated to get forces valid beyond the mean field approximation. preliminary results are presented for infinite symmetric and asymmetric nuclear matter up to pure neutron matter. | arxiv:nucl-th/0309012 |
we show that berkovich analytic geometry can be viewed as relative algebraic geometry in the sense of to \ " { e } n - - vaqui \ ' { e } - - vezzosi over the category of non - archimedean banach spaces. for any closed symmetric monoidal quasi - abelian category we can define a topology on certain subcategories of the of the category of affine schemes with respect to this category. by examining this topology for the category of banach spaces we recover the g - topology or the topology of admissible subsets on affinoids which is used in analytic geometry. this gives a functor of points approach to non - archimedean analytic geometry and in this way we also get definitions of ( higher ) non - archimedean analytic stacks. we demonstrate that the category of berkovich analytic spaces embeds fully faithfully into the category of varieties in our version of relative algebraic geometry. we also include a treatment of quasi - coherent sheaf theory in analytic geometry. along the way, we use heavily the homological algebra in quasi - abelian categories developed by schneiders. | arxiv:1312.0338 |
recommender systems have become increasingly important with the rise of the web as a medium for electronic and business transactions. one of the key drivers of this technology is the ease with which users can provide feedback about their likes and dislikes through simple clicks of a mouse. this feedback is commonly collected in the form of ratings, but can also be inferred from a user ' s browsing and purchasing history. recommender systems utilize users ' historical data to infer customer interests and provide personalized recommendations. the basic principle of recommendations is that significant dependencies exist between user - and item - centric activity, which can be learned in a data - driven manner to make accurate predictions. collaborative filtering is one family of recommendation algorithms that uses ratings from multiple users to predict missing ratings or uses binary click information to predict potential clicks. however, recommender systems can be more complex and incorporate auxiliary data such as content - based attributes, user interactions, and contextual information. | arxiv:2411.01843 |
the $ b _ { c } $ $ { \ to } $ $ j / { \ psi } { \ pi } $, $ { \ eta } _ { c } { \ pi } $ decays are studied in the scheme of the qcd factorization approach. the branching ratios are calculated with the asymptotic distribution amplitude of the pion. the charm quark mass effect is considered. we find that the mass effect on the branching ratios is small. | arxiv:0710.0031 |
we study a model of quantum cosmology originating from a classical model of gravitation where a self interacting scalar field is coupled to gravity with the metric undergoing a signature transition. we show that there are dual classical signature changing solutions, one at large scales and the other at small scales. it is possible to fine - tune the physics in both scales with an infinitesimal effective cosmological constant. | arxiv:gr-qc/9906115 |
computability theory is traditionally conceived as the theoretical basis of informatics. nevertheless, numerous proposals transcend computability theory, in particular by emphasizing interaction of modules, or components, parts, constituents, as a fundamental computing feature. in a technical framework, interaction requires composition of modules. hence, a most abstract, comprehensive theory of modules and their composition is required. to this end, we suggest a minimal set of postulates to characterize systems in the digital world that consist of interacting modules. for such systems, we suggest a calculus with a simple, yet most general composition operator which exhibits important properties, in particular associativity. we claim that this composition calculus provides not just another conceptual, formal framework, but that essentially all settings of modules and their composition can be based on this calculus. this claim is supported by a rich body of theorems, properties, special classes of modules, and case studies. | arxiv:2408.15031 |
we study the magnetotransport properties of patterned 3d topological insulator nanostructures with several leads, such as kinks or y - junctions, near the dirac point with analytical as well as numerical techniques. the interplay of the nanostructure geometry, the external magnetic field and the spin - momentum locking of the topological surface states lead to a richer magnetoconductance phenomenology as compared to straight nanowires. similar to straight wires, a quantized conductance with perfect transmission across the nanostructure can be realized across a kink when the input and output channels are pierced by a half - integer magnetic flux quantum. unlike for straight wires, there is an additional requirement depending on the orientation of the external magnetic field. a right - angle kink shows a unique $ \ pi $ - periodic magnetoconductance signature as a function of the in - plane angle of the magnetic field. for a y - junction, the transmission can be perfectly steered to either of the two possible output legs by a proper alignment of the external magnetic field. these magnetotransport signatures offer new ways to explore topological surface states and could be relevant for quantum transport experiments on nanostructures which can be realized with existing fabrication methods. | arxiv:1801.09230 |
aneutronic and nonradioactive properties make the proton - boron fusion a prospective candidate for fusion energy production through reactions following p + $ ^ { 11 } $ b $ \ rightarrow $ 3 $ { \ alpha } $ ( p - $ ^ { 11 } $ b ). however, it is difficult to achieve a thermal fusion ignition, since the low reaction cross - sections for center - of - mass energy below $ \ sim $ 100 kev. to realize fusion energy gain, it is essential to consider utilization of the maximum cross - section at the resonant peak of p - $ ^ { 11 } $ b fusion, and explore the nuclear reactions in plasma environment. in this work, p - $ ^ { 11 } $ b reactions triggered by interactions between energetic proton beams and laser - ablated boron plasma have been investigated. more than 200 times enhancement of $ { \ alpha } $ particle emission efficiency ( number ratio of escaping $ { \ alpha } $ particles and boron nuclei ) in plasma has been observed, compared with the cold boron. the proton beam transport path modulated by strong electro - magnetic fields in plasma could dominate the enhanced $ { \ alpha } $ particle generation, due to a longer collisional length. in addition, an $ { \ alpha } $ particle yield up to 1 $ \ times $ 10 $ ^ { 10 } $ / sr has been measured via the pitcher - catcher scheme in plasma. this work could benefit understanding of the plasma effects on nuclear reaction dynamics, and also enable opportunities to explore physics in laser fusion associated with advanced fusion fuels. | arxiv:2401.07253 |
climate is an evolving complex system with dynamic interactions and non - linear feedback mechanisms, shaping environmental and socio - economic outcomes. crop production is highly sensitive to such climatic fluctuations. this paper studies the price volatility of agricultural crops as influenced by meteorological variables ( and many other environmental, social and governance factors ), which is a critical challenge in sustainable finance, agricultural planning, and policy - making. as case studies, we choose the two indian states of madhya pradesh ( for soybean ) and odisha ( for brinjal ). we employ an exponential generalized autoregressive conditional heteroskedasticity ( egarch ) model to estimate the conditional volatility of the log returns of crop prices from 2012 to 2024. this study further explores the cross - correlations between volatility and the meteorological variables. further, a granger - causality test is carried out to analyze the causal effect of meteorological variables on the price volatility. finally, the seasonal auto - regressive integrated moving average with exogenous regressors ( sarimax ) and long short - term memory ( lstm ) models are implemented as simple machine learning models of price volatility with meteorological factors as exogenous variables. we believe that this will illustrate the usefulness of simple machine learning models in agricultural finance, and help the farmers to make informed decisions by considering climate patterns and making beneficial decisions with regard to crop rotation or allocations. in general, incorporating meteorological factors to assess agricultural performance could help to understand and reduce price volatility and possibly lead to economic stability. | arxiv:2503.11690 |
in this paper we investigate the use of quantum information to share classical secrets. while every quantum secret sharing scheme is a quantum error correcting code, the converse is not true. motivated by this we sought to find quantum codes which can be converted to secret sharing schemes. if we are interested in sharing classical secrets using quantum information, then we show that a class of pure $ [ [ n, 1, d ] ] _ q $ css codes can be converted to perfect secret sharing schemes. these secret sharing schemes are perfect in the sense the unauthorized parties do not learn anything about the secret. gottesman had given conditions to test whether a given subset is an authorized or unauthorized set ; they enable us to determine the access structure of quantum secret sharing schemes. for the secret sharing schemes proposed in this paper the access structure can be characterized in terms of minimal codewords of the classical code underlying the css code. this characterization of the access structure for quantum secret sharing schemes is thought to be new. | arxiv:0905.1661 |
the x - ray - flash xrf030723 was detected by the hete satellite and rapidly disseminated, allowing for an optical transient to be detected ~ 1 day after the burst. we discuss observations in the optical with magellan, which confirmed the fade of the optical transient. in a 2 - epoch too observation with chandra, we discovered a fading x - ray source spatially coincident with the optical transient. we present spectral fits to the x - ray data. we also discuss the possibility that the source underwent a rebrightening in the x - rays, as was observed in the optical. we find that the significance of a possible rebrightening is very low ( ~ 1 sigma ). | arxiv:astro-ph/0401020 |
even the most sensitive cosmic microwave background anisotropy experiments have signal to noise ratios < = 5, so that an accurate determination of the properties of the cosmological signal requires a careful assessment of the experimental noise. most of the experiments combine simultaneous multi - channel observations in which the presence of correlated noise is likely. this case is common for ground - based experiments in which an important fraction of the noise could be atmospheric in origin. here, the way to compute and determine the effects produced by this correlated noise is discussed ; in particular, the paper considers the tenerife experiments ( three radiometers at 10, 15 and 33 ghz with two independent receivers each ) showing how this effect has been taking into account properly in the more recent analysis of these data. it will be demonstrated that for each of the three radiometers of these experiments, the atmospheric noise is equivalent to a gaussian noise common to both channels with a coherence time smaller than the binning time, the net effect being an enhancement of the error - bars in the stacked scan as compared with the estimation for the case of pure uncorrelated noise. as expected from the spectral index of the atmosphere, the effect is more important at higher frequencies. the formalism is generalized and applied to the general case of simultaneous multi - channel observations. | arxiv:astro-ph/9702181 |
this paper was withdrawn by the editors of sigma as it essentially coincides with phys. lett. b 451 ( 1999 ), no. 3 - 4, 349 - 353. | arxiv:hep-th/0603148 |
this dissertation examines the impact of quantum gravity on electromagnetism and its backreaction, using perturbative general relativity as an effective field theory. our analysis involves quantum - correcting maxwell ' s equations to obtain a gauge - independent, real, and causal effective field equation that describes quantum gravitational effects on electromagnetism. additionally, we present a perturbative mechanism through which quantum gravity induces a dimension six coupling between a massive scalar and electromagnetism. to investigate the effects of electromagnetism on the gravitational sector, we derive an exact, dimensionally regulated, fourier mode sum for the lorentz gauge propagator of a massive photon on an arbitrary cosmological background supported by a scalar inflaton. this allows us to calculate the effective potential induced by photons. finally, we use a similar fourier mode sum for a time - dependent mass to study the effective force on the inflaton 0 - mode and its impact on reheating. | arxiv:2307.02580 |
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