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the angular distributions of the baryon - antibaryon low - mass enhancements seen in the charmless three - body baryonic b decays b + - > p pbar k +, b0 - > p pbar ks, and b0 - > p lambdabar pi - are reported. a quark fragmentation interpretation is supported, while the gluonic resonance picture is disfavored. searches for the theta + and theta + + pentaquarks in the relevant decay modes and possible glueball states g with 2. 2 gev / c2 < m - ppbar < 2. 4 gev / c2 in the ppbar systems give null results. we set upper limits on the products of branching fractions, b ( b0 - > theta + p ) \ times b ( theta + - > p ks ) < 2. 3 \ times 10 ^ { - 7 }, b ( b + - > theta + + pbar ) \ times b ( theta + + - > p k + ) < 9. 1 \ times 10 ^ { - 8 }, and b ( b + - > g k + ) \ times b ( g - > p pbar ) < 4. 1 \ times 10 ^ { - 7 } at the 90 % confidence level. the analysis is based on a 140 fb ^ { - 1 } data sample recorded on the upsilon ( 4s ) resonance with the belle detector at the kekb asymmetric - energy e + e - collider. | arxiv:hep-ex/0503047 |
in this article, we obtain existence and uniqueness results to some problems involving complex nonlinear fractional differential equations ( fdes ) in the closed unit disc of c. by help of these results, we prove that some ivps for some fractional differential equations with caputo or riemann - liouville derivative admit at least one local ( or unique ) solution continuous on a closed interval $ [ 0, r ] $ and real analytic on $ ( 0, r ), $ where $ 0 < r \ leq 1. $ | arxiv:1512.04780 |
we consider the sums of the form $ $ s = \ sum _ { x = 1 } ^ { n } \ exp \ big ( ( ax + b _ 1g _ 1 ^ x +... + b _ rg _ r ^ x ) / p \ big ) $ $, where $ p $ is prime and $ g _ 1,..., g _ r $ are primitive roots $ \ pmod p $. an almost forty years old problem of l. j. mordell asks to find a nontrivial estimate of $ s $ when at least two of the coefficients $ b _ 1,..., b _ r $ are not divizible by $ p $. here we obtain a nontrivial bound of the average of these sums when $ g _ 1 $ runs over all primitive roots $ \ pmod p $. | arxiv:0911.2832 |
in the paper, by using lupa \ c { s } integral inequality, the authors find some new inequalities for the complete elliptic integrals of the first and second kinds. these results improve some known inequalities. | arxiv:1301.4385 |
this paper presents a new contextual bandit algorithm, neuralbandit, which does not need hypothesis on stationarity of contexts and rewards. several neural networks are trained to modelize the value of rewards knowing the context. two variants, based on multi - experts approach, are proposed to choose online the parameters of multi - layer perceptrons. the proposed algorithms are successfully tested on a large dataset with and without stationarity of rewards. | arxiv:1409.8191 |
lorentz - violating gravity theories with a preferred foliation can have instantaneous propagation. nonetheless, it has been shown that black holes can still exist in such theories and the relevant notion of an event horizon has been dubbed ` universal horizon '. in stationary spacetimes the universal horizon has to reside in a region of spacetime where the killing vector associated with stationarity is spacelike. this raises the question of what happens to the universal horizon in the extremal limit, where no such region exists anymore. we use a decoupling limit approximation to study this problem. our results suggest that at the extremal limit, the extremal killing horizon appears to play the role of a degenerate universal horizon, despite being a null and not a spacelike surface, and hence not a leaf of the preferred foliation. | arxiv:1707.09283 |
this paper describes and compares some structure preserving techniques for the solution of linear discrete ill - posed problems with the t - product. a new randomized tensor singular value decomposition ( r - tsvd ) with a t - product is presented for low tubal rank tensor approximations. regularization of linear inverse problems by truncated tensor eigenvalue decomposition ( t - tevd ), truncated tsvd ( t - tsvd ), randomized t - tsvd ( rt - tsvd ), t - product golub - kahan bidiagonalization ( tgkb ) process, and t - product lanczos ( t - lanczos ) process are considered. a solution method that is based on reusing tensor krylov subspaces generated by the tgkb process is described. the regularization parameter is the number of iterations required by each method. the discrepancy principle is used to determine this parameter. solution methods that are based on truncated iterations are compared with solution methods that combine tikhonov regularization with the tgkb and t - lanczos processes. computed examples illustrate the performance of these methods when applied to image and gray - scale video restorations. our new rt - tsvd method is seen to require less cpu time and yields restorations of higher quality than the t - tsvd method. | arxiv:2110.02485 |
we review some recent progress in the study of electroweak interactions in nuclei within the susav2 - mec model. the model has the capability to predict ( anti ) neutrino scattering observables on different nuclei. the theoretical predictions are compared with the recent t2k $ \ nu _ \ mu - ^ { 16 } $ o data and good agreement is found at all kinematics. the results are very similar to those obtained for $ \ nu _ \ mu - ^ { 12 } $ c scattering, except at low energies, where some differences emerge. the role of meson - exchange currents in the two - particle two - hole channel is analyzed in some detail. in particular it is shown that the density dependence of these contributions is different from what is found for the quasielastic response. | arxiv:1804.03483 |
sirs models capture transmission dynamics of infectious diseases for which immunity is not lifelong. extending these models by a w compartment for individuals with waning immunity, the boosting of the immune system upon repeated exposure may be incorporated. previous analyses assumed identical waning rates from r to w and from w to s. this implicitly assumes equal length for the period of full immunity and of waned immunity. we relax this restriction, and allow an asymmetric partitioning of the total immune period. stability switches of the endemic equilibrium are investigated with a combination of analytic and numerical tools. then, continuation methods are applied to track bifurcations along the equilibrium branch. we find rich dynamics : hopf bifurcations, endemic double bubbles, and regions of bistability. our results highlight that the length of the period in which waning immunity can be boosted is a crucial parameter significantly influencing long term epidemiological dynamics. | arxiv:2201.07137 |
we study weyl fermions in a linear class of topologically trivial g \ " odel - type geometries in einstein ' s general relativity. we solve the weyl equation and evaluate in detail the energy eigenvalues and the corresponding wave functions. | arxiv:2107.03303 |
in this note we prove the genus 3 case of a conjecture of g. farkas and a. verra on the limit of the scorza correspondence for curves with a theta - null. specifically, we show that the limit of the scorza correspondence for a hyperelliptic genus 3 curve c is the union of the curve $ { x, \ sigma ( x ) ) $ ( where $ \ sigma $ is the hyperelliptic involution ), and twice the diagonal. our proof uses the geometry of the subsystem \ gamma _ { 00 } of the linear system 2 \ theta, and riemann identities for theta constants. | arxiv:1009.0375 |
let $ k $ be an unramified extension of $ \ mathbb { q } _ p $, and $ e $ a finite extension of $ k $ with ring of integers $ \ mathcal { o } _ e $. we associate to every finite type continuous $ \ mathcal { o } _ e $ - representation $ \ rho $ of $ \ mathrm { gal } ( \ overline { k } / k ) $ an \ ' etale $ ( \ varphi _ q, \ mathcal { o } _ k ^ { \ times } ) $ - module $ d _ { a _ { \ mathrm { mv }, e } } ^ { ( 0 ) } ( \ rho ) $ over $ a _ { \ mathrm { mv }, e } $, where $ a _ { \ mathrm { mv }, e } $ is the $ p $ - adic completion of a completed localization of the iwasawa algebra $ \ mathcal { o } _ e [ \ negthinspace [ \ mathcal { o } _ k ] \ negthinspace ] $. furthermore, we prove that the functor $ d _ { a _ { \ mathrm { mv }, e } } ^ { ( 0 ) } $ is fully faithful and exact. this functor is a $ p $ - adic analogue of $ d _ a ^ { ( 0 ) } $ in the recent work of breuil, herzig, hu, morra and schraen. | arxiv:2501.13580 |
representation learning, a task of learning latent vectors to represent entities, is a key task in improving search and recommender systems in web applications. various representation learning methods have been developed, including graph - based approaches for relationships among entities, sequence - based methods for capturing the temporal evolution of user activities, and content - based models for leveraging text and visual content. however, the development of a unifying framework that integrates these diverse techniques to support multiple applications remains a significant challenge. this paper presents omnisage, a large - scale representation framework that learns universal representations for a variety of applications at pinterest. omnisage integrates graph neural networks with content - based models and user sequence models by employing multiple contrastive learning tasks to effectively process graph data, user sequence data, and content signals. to support the training and inference of omnisage, we developed an efficient infrastructure capable of supporting pinterest graphs with billions of nodes. the universal representations generated by omnisage have significantly enhanced user experiences on pinterest, leading to an approximate 2. 5 % increase in sitewide repins ( saves ) across five applications. this paper highlights the impact of unifying representation learning methods, and we will open source the omnisage code by the time of publication. | arxiv:2504.17811 |
the orbital dynamics of fast spinning neutron stars encountering a massive black hole ( bh ) with unbounded orbits are investigated using the quadratic - in - spin mathisson - papapetrou - dixon ( mpd ) formulation. we consider the motion of the spinning neutron stars with astrophysically relevant speed in the gravity field of the bh. for such slow - speed scattering, the hyperbolic orbits followed by these neutron stars all have near the e = 1 eccentricity, and have distinct properties compared with those of e > > 1. we have found that compared with geodesic motion, the spin - orbit and spin - spin coupling will lead to a variation of scattering angles at spatial infinity, and this variation is more prominent for slow - speed scattering than fast - speed scattering. such a variation leads to an observable difference in pulse - arrival - time within a few hours of observation, and up to a few days or months for larger bh masses or longer spinning periods. such a relativistic pulsar - bh system also emits a burst of gravitational waves ( gws ) in the sensitivity band of lisa, and for optimal settings, can be seen up to 100 mpc away. a radio follow up of such a gw burst with ska or fast will allow for measuring the orbital parameters with high accuracy and testing the predictions of general relativity ( gr ). | arxiv:2110.03494 |
it was proposed that a remnant stable magnetar could be formed in a binary neutron - star merger, leading to a fast x - ray transient ( fxt ) that can last for thousands of seconds. recently, xue et al. suggested that cdf - s xt2 was exactly such a kind of source. if confirmed, such emission can be used to search for electromagnetic counterparts to gravitational wave events from binary neutron - star mergers that have short gamma - ray bursts and the corresponding afterglows seen off - axis and thus too weak to be detected. here we report the discovery of three new fxts, xrt 170901, xrt 030511, and xrt 110919, from preliminary search over chandra archival data. similar to cdf - s xt2, these new fxts had a very fast rise ( less than a few ten seconds ) and a plateau of x - ray flux $ \ sim $ $ 1. 0 \ times10 ^ { - 12 } $ erg s $ ^ { - 1 } $ cm $ ^ { - 2 } $ lasting for 1 - 2 ks, followed by a steep decay. their optical / ir counterparts, if present, are very weak, arguing against a stellar flare origin for these fxts. for xrt 170901, we identified a faint host galaxy with the source at the outskirts, very similar to cdf - s xt2. therefore, our newly discovered fxts are also strong candidates for magnetar - powered x - ray transients resulting from binary neutron star mergers. | arxiv:2201.06754 |
goals are first - class entities in a self - adaptive system ( sas ) as they guide the self - adaptation. a sas often operates in dynamic and partially unknown environments, which cause uncertainty that the sas has to address to achieve its goals. moreover, besides the environment, other classes of uncertainty have been identified. however, these various classes and their sources are not systematically addressed by current approaches throughout the life cycle of the sas. in general, uncertainty typically makes the assurance provision of sas goals exclusively at design time not viable. this calls for an assurance process that spans the whole life cycle of the sas. in this work, we propose a goal - oriented assurance process that supports taming different sources ( within different classes ) of uncertainty from defining the goals at design time to performing self - adaptation at runtime. based on a goal model augmented with uncertainty annotations, we automatically generate parametric symbolic formulae with parameterized uncertainties at design time using symbolic model checking. these formulae and the goal model guide the synthesis of adaptation policies by engineers. at runtime, the generated formulae are evaluated to resolve the uncertainty and to steer the self - adaptation using the policies. in this paper, we focus on reliability and cost properties, for which we evaluate our approach on the body sensor network ( bsn ) implemented in opendavinci. the results of the validation are promising and show that our approach is able to systematically tame multiple classes of uncertainty, and that it is effective and efficient in providing assurances for the goals of self - adaptive systems. | arxiv:1905.02228 |
a $ \ kappa $ - tree is said to be full if each of its limit levels omits no more than one potential branch. kunen asked whether a full $ \ kappa $ - souslin tree may consistently exist. shelah gave an affirmative answer of height a strong limit mahlo cardinal. here, it is shown that these trees may consistently exist at small cardinals. indeed, there can be $ \ aleph _ 3 $ many full $ \ aleph _ 2 $ - trees such that the product of any countably many of them is an $ \ aleph _ 2 $ - souslin tree. | arxiv:2308.00299 |
let $ k $ be a global function field and let $ \ phi \ in k [ x ] $. for all wandering basepoints $ b \ in k $, we show that there is a bound on the size of the elements of the dynamical zsigmondy set $ \ mathcal { z } ( \ phi, b ) $ that depends only on $ \ phi $, the poles of the $ b $, and $ k $. moreover, when we order $ b \ in \ mathcal { o } _ { k, s } $ by height, we show that $ \ mathcal { z } ( \ phi, b ) $ is empty on average. as an application, we prove that the inverse limit of the galois groups of iterates of $ \ phi ( x ) = x ^ d + f $ is a finite index subgroup of an iterated wreath product of cyclic groups. finally, we establish similar results on zsigmondy sets when $ k $ is the field of rational numbers or $ k $ is a quadratic imaginary field subject to an added stipulation : either zero has finite orbit under iteration of $ \ phi $ or the vojta conjecture for algebraic points on curves holds. | arxiv:1603.04459 |
in recent years, several studies on neural machine translation ( nmt ) have attempted to use document - level context by using a multi - encoder and two attention mechanisms to read the current and previous sentences to incorporate the context of the previous sentences. these studies concluded that the target - side context is less useful than the source - side context. however, we considered that the reason why the target - side context is less useful lies in the architecture used to model these contexts. therefore, in this study, we investigate how the target - side context can improve context - aware neural machine translation. we propose a weight sharing method wherein nmt saves decoder states and calculates an attention vector using the saved states when translating a current sentence. our experiments show that the target - side context is also useful if we plug it into nmt as the decoder state when translating a previous sentence. | arxiv:1909.00531 |
we study the problem of searching for and tracking a collection of moving targets using a robot with a limited field - of - view ( fov ) sensor. the actual number of targets present in the environment is not known a priori. we propose a search and tracking framework based on the concept of bayesian random finite sets ( rfss ). specifically, we generalize the gaussian mixture probability hypothesis density ( gm - phd ) filter which was previously applied for tracking problems to allow for simultaneous search and tracking with a limited fov sensor. the proposed framework can extract individual target tracks as well as estimate the number and the spatial density of targets. we also show how to use the gaussian process ( gp ) regression to extract and predict non - linear target trajectories in this framework. we demonstrate the efficacy of our techniques through representative simulations and a real data collected from an aerial robot. | arxiv:1812.09636 |
we have studied implications of the generic lopsided mass matrix of the charged leptons by taking the su ( 5 ) gut relation in the nearest - neighbor interaction ( nni ) basis. we have found four interesting relations among the lepton mixings and the quark ones, which are independent of details of the model. these relations are discussed by using the experimental data. we have also discussed the relation between u _ { e2 } and u _ { e3 } incuding the contribution from the neutrino mass matrix. we have presented the probable value u _ { e3 } = 0. 05 \ sim 0. 16, which is independent of the solar neutrino solutions. the cp violating quantity j _ { cp } is also discussed. | arxiv:hep-ph/0006099 |
a long - term goal of ai is to produce agents that can learn a diversity of skills throughout their lifetimes and continuously improve those skills via experience. a longstanding obstacle towards that goal is catastrophic forgetting, which is when learning new information erases previously learned information. catastrophic forgetting occurs in artificial neural networks ( anns ), which have fueled most recent advances in ai. a recent paper proposed that catastrophic forgetting in anns can be reduced by promoting modularity, which can limit forgetting by isolating task information to specific clusters of nodes and connections ( functional modules ). while the prior work did show that modular anns suffered less from catastrophic forgetting, it was not able to produce anns that possessed task - specific functional modules, thereby leaving the main theory regarding modularity and forgetting untested. we introduce diffusion - based neuromodulation, which simulates the release of diffusing, neuromodulatory chemicals within an ann that can modulate ( i. e. up or down regulate ) learning in a spatial region. on the simple diagnostic problem from the prior work, diffusion - based neuromodulation 1 ) induces task - specific learning in groups of nodes and connections ( task - specific localized learning ), which 2 ) produces functional modules for each subtask, and 3 ) yields higher performance by eliminating catastrophic forgetting. overall, our results suggest that diffusion - based neuromodulation promotes task - specific localized learning and functional modularity, which can help solve the challenging, but important problem of catastrophic forgetting. | arxiv:1705.07241 |
we present iram 30m and apex telescope observations of co ( 1 - 0 ) and co ( 2 - 1 ) lines in 36 group - dominant early - type galaxies, completing our molecular gas survey of dominant galaxies in the complete local - volume groups sample. we detect co emission in 12 of the galaxies at > 4sigma significance, with molecular gas masses in the range 0. 01 - 6x10 ^ 8 msol, as well as co in absorption in the non - dominant group member galaxy ngc 5354. in total 21 of the 53 clogs dominant galaxies are detected in co and we confirm our previous findings that they have low star formation rates ( 0. 01 - 1 msol / yr ) but short depletion times ( < 1gyr ) implying rapid replenishment of their gas reservoirs. comparing molecular gas mass with radio luminosity, we find that a much higher fraction of our group - dominant galaxies ( 60 + - 16 % ) are agn - dominated than is the case for the general population of ellipticals, but that there is no clear connection between radio luminosity and the molecular gas mass. using data from the literature, we find that at least 27 of the 53 clogs dominant galaxies contain hi, comparable to the fraction of nearby non - cluster early type galaxies detected in hi and significantly higher that the fraction in the virgo cluster. we see no correlation between the presence of an x - ray detected intra - group medium and molecular gas in the dominant galaxy, but find that the hi - richest galaxies are located in x - ray faint groups. morphological data from the literature suggests the cold gas component most commonly takes the form of a disk, but many systems show evidence of galaxy - galaxy interactions, indicating that they may have acquired their gas through stripping or mergers. we provide improved molecular gas mass estimates for two galaxies previously identified as being in the centres of cooling flows, ngc 4636 and ngc 5846, and find that they are relatively molecular gas poor compared to our other detected systems. | arxiv:1807.09110 |
discovering associations is of central importance in scientific practices. currently, most researches consider only linear association measured by correlation coefficient, which has its theoretical limitations. in this paper, we propose a new method for discovering association with copula entropy - - a universal applicable association measure for not only linear cases, but nonlinear cases. the advantage of the method based on copula entropy over traditional method is demonstrated on the nhanes data by discovering more biomedical meaningful associations. | arxiv:1907.12268 |
we study interaction - induced backscattering mechanism for helical edge states of a two dimensional topological insulator which is tunnel - coupled to a puddle located near the edge channel. the mechanism does not involve inelastic scattering and is due to the zero - mode fluctuations in a puddle. we discuss in detail a simple model of a puddle - a cavity in the bulk of the topological insulator. such a cavity also has helical edge states which are tunnel - coupled with helical states encompassing the topological insulator. we analyze effect of the edge current in the puddle. although averaged value of this current is equal to zero, its zero - mode fluctuations act, in the presence of electron - electron interaction, similar to magnetic flux thus allowing backscattering processes, which involve tunneling through the puddle. rectification of these fluctuations leads to a finite probability of backscattering. this effect is further enhanced due to dephasing process which is also dominated by zero - mode fluctuations. remarkably, for temperature exceeding level spacing in the puddle, the rate of backscattering does not depend on temperature in a good agreement with recent experiments. | arxiv:2410.04610 |
we consider thermal phases of holographic lattices at finite chemical potential in which a continuous internal bulk symmetry can be spontaneously broken. in the normal phase, translational symmetry is explicitly broken by the lattice and the only conserved quantities are related to time translations and the electric charge. the long wavelength excitations of the corresponding charge densities are described by incoherent hydrodynamics yielding two perturbative modes which are diffusive. in the broken phase an additional hydrodynamic degree of freedom couples to the local chemical potential and temperature and we write an effective theory describing the coupled system at leading order in a derivative expansion. | arxiv:1906.03132 |
the horton - strahler ( hs ) index $ r = \ max { ( i, j ) } + \ delta _ { i, j } $ has been shown to be relevant to a number of physical ( such at diffusion limited aggregation ) geological ( river networks ), biological ( pulmonary arteries, blood vessels, various species of trees ) and computational ( use of registers ) applications. here we revisit the enumeration problem of the hs index on the rooted, unlabeled, plane binary set of trees, and enumerate the same index on the ambilateral set of rooted, plane binary set of trees of $ n $ leaves. the ambilateral set is a set of trees whose elements cannot be obtained from each other via an arbitrary number of reflections with respect to vertical axes passing through any of the nodes on the tree. for the unlabeled set we give an alternate derivation to the existing exact solution. extending this technique for the ambilateral set, which is described by an infinite series of non - linear functional equations, we are able to give a double - exponentially converging approximant to the generating functions in a neighborhood of their convergence circle, and derive an explicit asymptotic form for the number of such trees. | arxiv:cond-mat/0108448 |
we propose a novel dnn based framework called the enhanced correlation matching based video frame interpolation network to support high resolution like 4k, which has a large scale of motion and occlusion. considering the extensibility of the network model according to resolution, the proposed scheme employs the recurrent pyramid architecture that shares the parameters among each pyramid layer for optical flow estimation. in the proposed flow estimation, the optical flows are recursively refined by tracing the location with maximum correlation. the forward warping based correlation matching enables to improve the accuracy of flow update by excluding incorrectly warped features around the occlusion area. based on the final bi - directional flows, the intermediate frame at arbitrary temporal position is synthesized using the warping and blending network and it is further improved by refinement network. experiment results demonstrate that the proposed scheme outperforms the previous works at 4k video data and low - resolution benchmark datasets as well in terms of objective and subjective quality with the smallest number of model parameters. | arxiv:2111.08869 |
the response of superconducting devices to electromagnetic radiation is a core concept implemented in diverse applications, ranging from the currently used voltage standard to single photon detectors in astronomy. suprisingly, a sufficiently high power subgap radiation may stimulate superconductivity itself. the possibility of stimulating type ii superconductors, in which the radiation may interact also with vortex cores, remains however unclear. here we report on superconductivity enhanced by ghz radiation in type ii superconducting pb films in the presence of vortices. the stimulation effect is more clearly observed in the upper critical field and less pronounced in the critical temperature. the magnetic field dependence of the vortex related microwave losses in a film with periodic pinning reveals a reduced dissipation of mobile vortices in the stimulated regime due to a reduction of the core size. results of numerical simulations support the validy of this conclusion. our findings may have intriguing connections with holographic superconductors in which the possibility of stimulation is under current debate. | arxiv:1503.01610 |
we study the problem of adversarial combinatorial bandit with a switching cost $ \ lambda $ for a switch of each selected arm in each round, considering both the bandit feedback and semi - bandit feedback settings. in the oblivious adversarial case with $ k $ base arms and time horizon $ t $, we derive lower bounds for the minimax regret and design algorithms to approach them. to prove these lower bounds, we design stochastic loss sequences for both feedback settings, building on an idea from previous work in dekel et al. ( 2014 ). the lower bound for bandit feedback is $ \ tilde { \ omega } \ big ( ( \ lambda k ) ^ { \ frac { 1 } { 3 } } ( ti ) ^ { \ frac { 2 } { 3 } } \ big ) $ while that for semi - bandit feedback is $ \ tilde { \ omega } \ big ( ( \ lambda k i ) ^ { \ frac { 1 } { 3 } } t ^ { \ frac { 2 } { 3 } } \ big ) $ where $ i $ is the number of base arms in the combinatorial arm played in each round. to approach these lower bounds, we design algorithms that operate in batches by dividing the time horizon into batches to restrict the number of switches between actions. for the bandit feedback setting, where only the total loss of the combinatorial arm is observed, we introduce the batched - exp2 algorithm which achieves a regret upper bound of $ \ tilde { o } \ big ( ( \ lambda k ) ^ { \ frac { 1 } { 3 } } t ^ { \ frac { 2 } { 3 } } i ^ { \ frac { 4 } { 3 } } \ big ) $ as $ t $ tends to infinity. in the semi - bandit feedback setting, where all losses for the combinatorial arm are observed, we propose the batched - broad algorithm which achieves a regret upper bound of $ \ tilde { o } \ big ( ( \ lambda k ) ^ { \ frac { 1 } { 3 } } ( ti ) ^ { \ frac { 2 } { 3 } } \ big ) $. | arxiv:2404.01883 |
we study chern - simons theory with a complex g _ c or a real g x g gauge group on a manifold with boundary - this includes lorentzian and euclidean ( anti - ) de sitter ( e / a ) ds gravity for g = su ( 2 ) or g = sl ( 2, r ). we show that there is a canonical choice of boundary conditions that leads to an unambiguous, fully covariant and gauge invariant, off - shell derivation of the boundary action - a g _ c / g or g wzw model, coupled in a gauge invariant way to the boundary value of the gauge field. in particular, for ( e / a ) ds gravity, the boundary action is a wzw model with target space ( e / a ) ds _ 3, reminiscent of a worldsheet for worldsheet mechanism. we discuss in some detail the properties of the boundary theories that arise and we confront our results with various related constructions in the literature. | arxiv:hep-th/0210089 |
in this talk some recent results in the quantization of chern - simons field theories in the coulomb gauge will be presented. in the first part, the consistency of the chern - simons field theories in this gauge is proven using the dirac ' s canonical formalism for constrained systems. despite the presence of non - trivial self - interactions in the gauge fixed functional, it will be shown that the commutation relations between the fields are trivial at any perturbative order in the absence of couplings with matter fields. if these couplings are present, instead, the commutation relations become rather involved, but it is still possible to study their main properties and to show that they vanish at the tree level. in the second part of the talk the perturbative aspects of chern - simons field theories in the coulomb gauge will be analysed. in particular, it will be shown by explicit computations and in a regularization independent way that there are no radiative contributions to the $ n - $ point correlation functions. finally the feynman rules in the coulomb gauge will be derived on a three dimensional manifold with a spatial section given by a closed and orientable riemann surface. | arxiv:hep-th/9712076 |
the discovery of community structures in social networks has gained significant attention since it is a fundamental problem in understanding the networks ' topology and functions. however, most social network data are collected from partially observable networks with both missing nodes and edges. in this paper, we address a new problem of detecting overlapping community structures in the context of such an incomplete network, where communities in the network are allowed to overlap since nodes belong to multiple communities at once. to solve this problem, we introduce kromfac, a new framework that conducts community detection via regularized nonnegative matrix factorization ( nmf ) based on the kronecker graph model. specifically, from an inferred kronecker generative parameter matrix, we first estimate the missing part of the network. as our major contribution to the proposed framework, to improve community detection accuracy, we then characterize and select influential nodes ( which tend to have high degrees ) by ranking, and add them to the existing graph. finally, we uncover the community structures by solving the regularized nmf - aided optimization problem in terms of maximizing the likelihood of the underlying graph. furthermore, adopting normalized mutual information ( nmi ), we empirically show superiority of our kromfac approach over two baseline schemes by using both synthetic and real - world networks. | arxiv:1801.00132 |
mixed moving average processes appear in the ergodic decomposition of stationary symmetric \ alpha - stable ( s \ alpha s ) processes. they correspond to the dissipative part of " deterministic " flows generating s \ alpha s processes ( rosinski, 1995 ). along these lines we study stationary increment and self - similar s \ alpha s processes. since the classes of stationary increment and self - similar processes can be embedded into the class of stationary processes by the masani and lamperti transformations, respectively, we characterize these classes of s \ alpha s processes in terms of nonsingular flows and the related cocycles. we illustrate this approach considering various examples of self - similar mixed moving average s \ alpha s processes introduced in ( surgailis, rosinski, mandrekar and cambanis, 1992 ). | arxiv:1211.6419 |
estimating 3d full - body avatars from ar / vr devices is essential for creating immersive experiences in ar / vr applications. this task is challenging due to the limited input from head mounted devices, which capture only sparse observations from the head and hands. predicting the full - body avatars, particularly the lower body, from these sparse observations presents significant difficulties. in this paper, we are inspired by the inherent property of the kinematic tree defined in the skinned multi - person linear ( smpl ) model, where the upper body and lower body share only one common ancestor node, bringing the potential of decoupled reconstruction. we propose a stratified approach to decouple the conventional full - body avatar reconstruction pipeline into two stages, with the reconstruction of the upper body first and a subsequent reconstruction of the lower body conditioned on the previous stage. to implement this straightforward idea, we leverage the latent diffusion model as a powerful probabilistic generator, and train it to follow the latent distribution of decoupled motions explored by a vq - vae encoder - decoder model. extensive experiments on amass mocap dataset demonstrate our state - of - the - art performance in the reconstruction of full - body motions. | arxiv:2405.20786 |
principal component analysis ( pca ) is a well - known linear dimension - reduction technique designed for euclidean data. in a wide spectrum of applied fields, however, it is common to observe multivariate circular data ( also known as toroidal data ), rendering spurious the use of pca on it due to the periodicity of its support. this paper introduces toroidal ridge pca ( tr - pca ), a novel construction of pca for bivariate circular data that leverages the concept of density ridges as a flexible first principal component analog. two reference bivariate circular distributions, the bivariate sine von mises and the bivariate wrapped cauchy, are employed as the parametric distributional basis of tr - pca. efficient algorithms are presented to compute density ridges for these two distribution models. a complete pca methodology adapted to toroidal data ( including scores, variance decomposition, and resolution of edge cases ) is introduced and implemented in the companion r package ridgetorus. the usefulness of tr - pca is showcased with a novel case study involving the analysis of ocean currents on the coast of santa barbara. | arxiv:2212.10856 |
model - free control ( mfc ), which is easy to implement both from software and hardware viewpoints, permits the introduction of a high level control synthesis for the industrial internet of things ( iiot ) and the industry 4. 0. the choice of the user diagram protocol ( udp ) as the internet protocol permits to neglect the latency. in spite of most severe packet losses, convincing computer simulations and laboratory experiments show that mfc exhibits a good quality of service ( qos ) and behaves better than a classic pi regulator. | arxiv:2004.12156 |
we investigate slice - quaternionic hopf surfaces. in particular, we construct new structures of slice - quaternionic manifold on $ \ mathbb { s } ^ 1 \ times \ mathbb { s } ^ 7 $, we study their group of automorphisms and their deformations. | arxiv:1606.06128 |
recent discussions of the origins of the thermodynamical asymmetry ( " the arrow of time " ) by huw price and others are critically assessed. this serves as a motivation for consideration of relationship between thermodynamical and cosmological causes. although the project of clarification of the thermodynamical explanandum is certainly welcome, price excludes another interesting option, at least as viable as the sort of acausal - particular approach he favors, and arguably more in the spirit of boltzmann himself. thus, the competition of explanatory projects includes three horses, not two. in addition, it is the acausal - particular approach that could benefit enormously from dissociation from fanciful ideas of low - entropy future boundary conditions entertained by price. novel revolutionary developments in observational cosmology, as well as in the nascent astrophysical discipline of physical eschatology, have obliterated such hypotheses. also, the acausal - anthropic approach we propose, offers another clear instance of disteleological nature of the anthropic principle. | arxiv:physics/0407045 |
we propose orbcam, a lensless architecture for imaging with spherical sensors. prior work in lensless imager techniques have focused largely on using planar sensors ; for such designs, it is important to use a modulation element, e. g. amplitude or phase masks, to construct a invertible imaging system. in contrast, we show that the diversity of pixel orientations on a curved surface is sufficient to improve the conditioning of the mapping between the scene and the sensor. hence, when imaging on a spherical sensor, all pixels can have the same angular response function such that the lensless imager is comprised of pixels that are identical to each other and differ only in their orientations. we provide the computational tools for the design of the angular response of the pixels in a spherical sensor that leads to well - conditioned and noise - robust measurements. we validate our design in both simulation and a lab prototype. the implications of our design is that the lensless imaging can be enabled easily for curved and flexible surfaces thereby opening up a new set of application domains. | arxiv:2306.15953 |
we study actively labeling streaming data, where an active learner is faced with a stream of data points and must carefully choose which of these points to label via an expensive experiment. such problems frequently arise in applications such as healthcare and astronomy. we first study a setting when the data ' s inputs belong to one of $ k $ discrete distributions and formalize this problem via a loss that captures the labeling cost and the prediction error. when the labeling cost is $ b $, our algorithm, which chooses to label a point if the uncertainty is larger than a time and cost dependent threshold, achieves a worst - case upper bound of $ \ widetilde { o } ( b ^ { \ frac { 1 } { 3 } } k ^ { \ frac { 1 } { 3 } } t ^ { \ frac { 2 } { 3 } } ) $ on the loss after $ t $ rounds. we also provide a more nuanced upper bound which demonstrates that the algorithm can adapt to the arrival pattern, and achieves better performance when the arrival pattern is more favorable. we complement both upper bounds with matching lower bounds. we next study this problem when the inputs belong to a continuous domain and the output of the experiment is a smooth function with bounded rkhs norm. after $ t $ rounds in $ d $ dimensions, we show that the loss is bounded by $ \ widetilde { o } ( b ^ { \ frac { 1 } { d + 3 } } t ^ { \ frac { d + 2 } { d + 3 } } ) $ in an rkhs with a squared exponential kernel and by $ \ widetilde { o } ( b ^ { \ frac { 1 } { 2d + 3 } } t ^ { \ frac { 2d + 2 } { 2d + 3 } } ) $ in an rkhs with a mat \ ' ern kernel. our empirical evaluation demonstrates that our method outperforms other baselines in several synthetic experiments and two real experiments in medicine and astronomy. | arxiv:2304.06808 |
we present a new relation between an invariant of singularities in characteristic zero ( the log canonical threshold ) and an invariant of singularities defined via the frobenius morphism in positive characteristic ( the f - pure threshold ). we show that the set of limit points of sequences of the form ( c _ p ), where c _ p is the f - pure threshold of an ideal on an n - dimensional smooth variety in characteristic p, coincides with the set of log canonical thresholds of ideals on n - dimensional smooth varieties in characteristic zero. we prove this by combining results of hara and yoshida with non - standard constructions. | arxiv:1106.0207 |
we motive and calculate newton - - cotes quadrature integration variance and compare it directly with monte carlo ( mc ) integration variance. we find an equivalence between deterministic quadrature sampling and random mc sampling by noting that mc random sampling is statistically indistinguishable from a method that uses deterministic sampling on a randomly shuffled ( permuted ) function. we use this statistical equivalence to regularize the form of permissible bayesian quadrature integration priors such that they are guaranteed to be objectively comparable with mc. this leads to the proof that simple quadrature methods have expected variances that are less than or equal to their corresponding theoretical mc integration variances. separately, using bayesian probability theory, we find that the theoretical standard deviations of the unbiased errors of simple newton - - cotes composite quadrature integrations improve over their worst case errors by an extra dimension independent factor $ \ propto n ^ { - 1 / 2 } $. this dimension independent factor is validated in our simulations. | arxiv:1908.00947 |
in this paper, we present a nodal hydraulic head estimation methodology for water distribution networks ( wdn ) based on an unscented kalman filter ( ukf ) scheme with application to leak localization. the ukf refines an initial estimation of the hydraulic state by considering the prediction model, as well as available pressure and demand measurements. to this end, it provides customized prediction and data assimilation steps. additionally, the method is enhanced by dynamically updating the prediction function weight matrices. performance testing on the modena benchmark under realistic conditions demonstrates the method ' s effectiveness in enhancing state estimation and data - driven leak localization. | arxiv:2311.15875 |
in this article we use a method of finding the index of a complex - valued function by determined number of arithmetic operations to describe an algorithm of localization of roots of square - free polynomials. we give an estimation of the number of arithmetic operations for the described algorithm. | arxiv:2306.04576 |
in an era where symbolic mathematical equations are indispensable for modeling complex natural phenomena, scientific inquiry often involves collecting observations and translating them into mathematical expressions. recently, deep learning has emerged as a powerful tool for extracting insights from data. however, existing models typically specialize in either numeric or symbolic domains, and are usually trained in a supervised manner tailored to specific tasks. this approach neglects the substantial benefits that could arise from a task - agnostic multi - modal understanding between symbolic equations and their numeric counterparts. to bridge the gap, we introduce snip, a symbolic - numeric integrated pre - training model, which employs contrastive learning between symbolic and numeric domains, enhancing their mutual similarities in the embeddings. by performing latent space analysis, we observe that snip provides cross - domain insights into the representations, revealing that symbolic supervision enhances the embeddings of numeric data and vice versa. we evaluate snip across diverse tasks, including symbolic - to - numeric mathematical property prediction and numeric - to - symbolic equation discovery, commonly known as symbolic regression. results show that snip effectively transfers to various tasks, consistently outperforming fully supervised baselines and competing strongly with established task - specific methods, especially in the low data regime scenarios where available data is limited. code and model are available at : https : / / github. com / deep - symbolic - mathematics / multimodal - math - pretraining | arxiv:2310.02227 |
the current paper is devoted to the study of semilinear dispersal evolution equations of the form $ $ u _ t ( t, x ) = ( \ mathcal { a } u ) ( t, x ) + u ( t, x ) f ( t, x, u ( t, x ) ), \ quad x \ in \ mathcal { h }, $ $ where $ \ mathcal { h } = \ rr ^ n $ or $ \ zz ^ n $, $ \ mathcal { a } $ is a random dispersal operator or nonlocal dispersal operator in the case $ \ mathcal { h } = \ rr ^ n $ and is a discrete dispersal operator in the case $ \ mathcal { h } = \ zz ^ n $, and $ f $ is periodic in $ t $, asymptotically periodic in $ x $ ( i. e. $ f ( t, x, u ) - f _ 0 ( t, x, u ) $ converges to 0 as $ \ | x \ | \ to \ infty $ for some time and space periodic function $ f _ 0 ( t, x, u ) $ ), and is of kpp type in $ u $. it is proved that liouville type property for such equations holds, that is, time periodic strictly positive solutions are unique. it is also proved that if $ u \ equiv 0 $ is a linearly unstable solution to the time and space periodic limit equation of such an equation, then it has a unique stable time periodic strictly positive solution and has a spatial spreading speed in every direction. | arxiv:1308.0531 |
when experimental errors are ignored in an experiment, the subsequent analysis of its results becomes questionable. we develop tests to detect systematic errors in quantum experiments where only a finite amount of data is recorded and apply these tests to tomographic data taken in an ion trap experiment. we put particular emphasis on quantum state tomography and present three detection methods : the first two employ linear inequalities while the third is based on the generalized likelihood ratio. | arxiv:1204.3644 |
several recent studies advocate the use of spectral discriminators, which evaluate the fourier spectra of images for generative modeling. however, the effectiveness of the spectral discriminators is not well interpreted yet. we tackle this issue by examining the spectral discriminators in the context of perceptual image super - resolution ( i. e., gan - based sr ), as sr image quality is susceptible to spectral changes. our analyses reveal that the spectral discriminator indeed performs better than the ordinary ( a. k. a. spatial ) discriminator in identifying the differences in the high - frequency range ; however, the spatial discriminator holds an advantage in the low - frequency range. thus, we suggest that the spectral and spatial discriminators shall be used simultaneously. moreover, we improve the spectral discriminators by first calculating the patch - wise fourier spectrum and then aggregating the spectra by transformer. we verify the effectiveness of the proposed method twofold. on the one hand, thanks to the additional spectral discriminator, our obtained sr images have their spectra better aligned to those of the real images, which leads to a better pd tradeoff. on the other hand, our ensembled discriminator predicts the perceptual quality more accurately, as evidenced in the no - reference image quality assessment task. | arxiv:2307.12027 |
we present results from the first self - consistent multi - fluid simulations of chromospheric magnetic reconnection in a weakly ionized reacting plasma. we simulate two dimensional magnetic reconnection in a harris current sheet with a numerical model which includes ion - neutral scattering collisions, ionization, recombination, optically thin radiative loss, collisional heating, and thermal conduction. in the resulting tearing mode reconnection the neutral and ion fluids become decoupled upstream from the reconnection site, creating an excess of ions in the reconnection region and therefore an ionization imbalance. ion recombination in the reconnection region, combined with alfv \ ' { e } nic outflows, quickly removes ions from the reconnection site, leading to a fast reconnection rate independent of lundquist number. in addition to allowing fast reconnection, we find that these non - equilibria partial ionization effects lead to the onset of the nonlinear secondary tearing instability at lower values of the lundquist number than has been found in fully ionized plasmas. these simulations provide evidence that magnetic reconnection in the chromosphere could be responsible for jet - like transient phenomena such as spicules and chromospheric jets. | arxiv:1210.1807 |
we show that the maximum entropy hypothesis can successfully explain the distribution of stresses on compact clusters of particles within disordered mechanically stable packings of soft, isotropically stressed, frictionless disks above the jamming transition. we show that, in our two dimensional case, it becomes necessary to consider not only the stress but also the maxwell - cremona force - tile area, as a constraining variable that determines the stress distribution. the importance of the force - tile area had been suggested by earlier computations on an idealized force - network ensemble. | arxiv:1410.4631 |
we study the classical bargaining problem and its two canonical solutions, ( nash and kalai - smorodinsky ), from a novel point of view : we ask for stability of the solution if both players are able distort the underlying bargaining process by reference to a third party ( e. g. a court ). by exploring the simplest case, where decisions of the third party are made randomly we obtain a stable solution, where players do not have any incentive to refer to such a third party. while neither the nash nor the kalai - smorodinsky solution are able to ensure stability in case reference to a third party is possible, we found that the kalai - smorodinsky solution seems to always dominate the stable allocation which constitutes novel support in favor of the latter. | arxiv:1707.02418 |
this paper presents a novel lagrangian approach to attitude tracking for rigid spacecraft using unit quaternions, where the motion equations of a spacecraft are described by a four degrees of freedom lagrangian dynamics subject to a holonomic constraint imposed by the norm of a unit quaternion. the basic energy - conservation property as well as some additional useful properties of the lagrangian dynamics are explored, enabling to develop quaternion - based attitude tracking controllers by taking full advantage of a broad class of tracking control designs for mechanical systems based on energy - shaping methodology. global tracking of a desired attitude on the unit sphere is achieved by designing control laws that render the tracking error on the four - dimensional euclidean space to converge to the origin. the topological constraints for globally exponentially tracking by a quaternion - based continuous controller and singularities in controller designs based on any three - parameter representation of the attitude are then avoided. using this approach, a full - state feedback controller is first developed, and then several important issues, such as robustness to noise in quaternion measurements, unknown on - orbit torque disturbances, uncertainty in the inertial matrix, and lack of angular - velocity measurements are addressed progressively, by designing a hybrid state - feedback controller, an adaptive hybrid state - feedback controller, and an adaptive hybrid attitude - feedback controller. global asymptotic stability is established for each controller. simulations are included to illustrate the theoretical results. | arxiv:2202.05227 |
in this article we first review the past decade of efforts in detecting the missing baryons in the warm hot intergalactic medium ( whim ) and summarize the current state of the art by updating the baryon census and physical state of the detected baryons in the local universe. we then describe observational strategies that should enable a significant step forward in the next decade, while waiting for the step - up in quality offered by future missions. in particular we design a multi - mega - second and multiple cycle xmm - newton legacy program ( which we name the ultimate roaming baryon exploration, or urbe ) aimed to secure detections of the peaks in the density distribution of the universe missing baryons over their entire predicted range of temperatures. | arxiv:1611.03722 |
the studies of the quantum corrections for the anisotropy parameter, $ \ eta ( = \ xi _ r / \ xi _ b ) $, for the improved actions, $ \ beta ( c _ 0 l ( { plaq. } ) + c _ 1 l ( { rect. } ) ) $, are proceeded in the medium to strong coupling region on anisotropic lattices. the global features for the $ \ eta $ parameters as a function of $ \ beta $ and the coefficient $ c _ { 1 } $ have been clarified. it has been found by the perturbative analysis that as $ c _ 1 $ decreases, the slope of the $ \ eta ( \ beta ) $ becomes less steep and for the actions whose $ c _ { 1 } $ is less than - 0. 160, $ \ eta $ decreases as $ \ beta $ decreases, contrary to the case of the standard action. in the medium to strong coupling region, the $ \ eta $ parameter begins to increase as $ \ beta $ decreases for all $ c _ { 1 } $. this means that for the actions with $ c _ { 1 } < - 0. 160 $, the one - loop perturbative results for $ \ eta $ break down qualitatively and the $ \ eta $ parameters have a dip. as a result of this dip structure the $ \ eta $ for iwasaki ' s action remains close to unity in the wide range of $ \ beta $. | arxiv:hep-lat/0001004 |
next - generation distributed computing networks ( e. g., edge and fog computing ) enable the efficient delivery of delay - sensitive, compute - intensive applications by facilitating access to computation resources in close proximity to end users. many of these applications ( e. g., augmented / virtual reality ) are also data - intensive : in addition to user - specific ( live ) data streams, they require access to ( static ) digital objects ( e. g., image database ) to complete the required processing tasks. when required objects are not available at the servers hosting the associated service functions, they must be fetched from other edge locations, incurring additional communication cost and latency. in such settings, overall service delivery performance shall benefit from jointly optimized decisions around ( i ) routing paths and processing locations for live data streams, together with ( ii ) cache selection and distribution paths for associated digital objects. in this paper, we address the problem of dynamic control of data - intensive services over edge cloud networks. we characterize the network stability region and design the first throughput - optimal control policy that coordinates processing and routing decisions for both live and static data - streams. numerical results demonstrate the superior performance ( e. g., throughput, delay, and resource consumption ) obtained via the novel multi - pipeline flow control mechanism of the proposed policy, compared with state - of - the - art algorithms that lack integrated stream processing and data distribution control. | arxiv:2205.14735 |
we present new designs for quantum random access memory. more precisely, for each function, $ f : \ mathbb { f } _ 2 ^ n \ rightarrow \ mathbb { f } _ 2 ^ d $, we construct oracles, $ \ mathcal { o } _ f $, with the property \ begin { equation } \ mathcal { o } _ f \ left | x \ right \ rangle _ n \ left | 0 \ right \ rangle _ d = \ left | x \ right \ rangle _ n \ left | f ( x ) \ right \ rangle _ d. \ end { equation } our methods are based on the walsh - hadamard transform of $ f $, viewed as an integer valued function. in general, the complexity of our method scales with the sparsity of the walsh - hadamard transform and not the sparsity of $ f $, yielding more favorable constructions in cases such as binary optimization problems and function with low - degree walsh - hadamard transforms. furthermore, our design comes with a tuneable amount of ancillas that can trade depth for size. in the ancilla - free design, these oracles can be $ \ epsilon $ - approximated so that the clifford + $ t $ depth is $ o \ left ( \ left ( n + \ log _ 2 \ left ( \ tfrac { d } { \ epsilon } \ right ) \ right ) \ mathcal { w } _ f \ right ) $, where $ \ mathcal { w } _ f $ is the number of nonzero components in the walsh - hadamard transform. the depth of the shallowest version is $ o \ left ( n + \ log _ 2 \ left ( \ tfrac { d } { \ epsilon } \ right ) \ right ) $, using $ n + d \ mathcal { w } _ f $ qubit. the connectivity of these circuits is also only logarithmic in $ \ mathcal { w } _ f $. as an application, we show that for boolean functions with low approximate degrees ( as in the case of read - once formulas ) the complexities of the corresponding qram oracles scale only as $ 2 ^ { \ widetilde { o } \ left ( \ sqrt { n } \ log _ 2 \ left ( n \ right ) \ right ) } $. | arxiv:2405.20225 |
the mid - infrared heating of interfacial water with different initial temperatures is studied using non - equilibrium molecular dynamics simulation. it is found that under the irradiation of a pulse at 3360 - 3380 $ cm ^ { - 1 } $ the two - dimensional water monolayer on a hydrophilic surface at a lower initial temperature acquires a much larger temperature jump. the mechanism beneath this counterintuitive phenomenon is the enhanced transition efficiency of the asymmetric oh stretching vibration due to the specific oriented configuration of water molecules at lower initial temperatures. the understanding of the anomalous phenomenon clarifies the sensitivity of the interfacial properties of water molecules to the temperature. | arxiv:2207.08676 |
we study the natural labeling of the one dimensional representations for ariki - koike algebras at roots of unity. for hecke algebras of types a and b, some of these representations can be identified with the socle of the steinberg representation of a finite reductive group. we here give closed formulas for them. this uses, in particular, several results concerning crystal isomorphisms and the mullineux involution. | arxiv:1509.03417 |
the gravitational evolution of scale free initial spectra $ p ( k ) \ propto k ^ n $ in an einstein - de sitter universe is widely believed to be self - similar for $ - 3 < n < 4 $. however, for $ - 3 < n < - 1 $ the existence of self - similar scaling has not been adequately demonstrated. here we investigate the possible breaking of self - similar scaling due to the nonlinear contributions of long wave modes. for $ n < - 1 $ the nonlinear terms in the fourier space fluid equations contain terms that diverge due to contributions from wavenumber $ k \ to 0 $ ( the long wave limit ). to assess the possible dynamical effects of this divergence the limit of long wave contributions is investigated in detail using two different analytical approaches. perturbative contributions to the power spectrum are examined. it is shown that for $ n < - 1 $ there are divergent contributions at all orders. however, at every order the leading order divergent terms cancel out exactly. this does not rule out the existence of a weaker but nevertheless divergent net contribution. the second approach consists of a non - perturbative approximation, developed to study the nonlinear effects of long wave mode coupling. a solution for the phase shift of the fourier space density is obtained which is divergent for $ n < - 1 $. a kinematical interpretation of the divergence of the phase shift, related to the translational motion induced by the large - scale bulk velocity, is given. our analysis indicates that the amplitude of the density is { \ it not } affected by the divergent terms. thus both analytical approaches lead to the conclusion that the self - similar scaling of physically relevant measures of the growth of density perturbations is preserved. | arxiv:astro-ph/9503025 |
given groupoids $ g $ and $ h $ and a $ ( g, h ) $ - equivalence $ x $ we may form the transformation groupoid $ g \ ltimes x \ rtimes h $. given a separable groupoid dynamical system $ ( a, g \ ltimes x \ rtimes h, \ omega ) $ we may restrict $ \ omega $ to an action of $ g \ ltimes x $ on $ a $ and form the crossed product $ a \ rtimes g \ ltimes x $. we show that there is an action of $ h $ on $ a \ rtimes g \ ltimes x $ and that the iterated crossed product $ ( a \ rtimes g \ ltimes x ) \ rtimes h $ is naturally isomorphic to the crossed product $ a \ rtimes ( g \ ltimes x \ rtimes h ) $. | arxiv:1206.2066 |
nasa ' s interface region imaging spectrograph ( iris ) provides high resolution observations of the solar atmosphere through uv spectroscopy and imaging. since the launch of iris in june 2013, we have conducted systematic observation campaigns in coordination with the swedish 1 - m solar telescope ( sst ) on la palma. the sst provides complementary high - resolution observations of the photosphere and chromosphere. the sst observations include spectro - polarimetric imaging in photospheric fe i lines and spectrally - resolved imaging in the chromospheric ca ii 8542 a, h - alpha, and ca ii k lines. we present a database of co - aligned iris and sst datasets that is open for analysis to the scientific community. the database covers a variety of targets including active regions, sunspots, plage, quiet sun, and coronal holes. | arxiv:2005.14175 |
we propose a new approach to promote safety in classification tasks with established concepts. our approach - - called a conceptual safeguard - - acts as a verification layer for models that predict a target outcome by first predicting the presence of intermediate concepts. given this architecture, a safeguard ensures that a model meets a minimal level of accuracy by abstaining from uncertain predictions. in contrast to a standard selective classifier, a safeguard provides an avenue to improve coverage by allowing a human to confirm the presence of uncertain concepts on instances on which it abstains. we develop methods to build safeguards that maximize coverage without compromising safety, namely techniques to propagate the uncertainty in concept predictions and to flag salient concepts for human review. we benchmark our approach on a collection of real - world and synthetic datasets, showing that it can improve performance and coverage in deep learning tasks. | arxiv:2411.04342 |
we construct both local states and scattering states with finite energy in global ads by inserting properly regularized operators in the cft of arbitrary conformal dimension $ ( \ delta ) $ at an instant of time. we give the state fixed angular momentum $ ( \ ell ) $ by integrating the result over a sphere with appropriate spherical harmonics. the energy of the states and their angular resolution is computed with cft operator methods and is independent of having an ads interpretation. in the semiclassical limit of large conformal dimension operators, these correspond to single particles localized within subads scales with width $ 1 / \ sqrt { \ delta } $ in ads units, whose subsequent evolution is controlled by bulk geodesics. our construction allows us to place a particle in any desired geodesic. for radial geodesics, we show that the amplitude to produce the desired state can be thought of as a regularized tunneling amplitude from the boundary to the radial turning point of the radial geodesic, while for other geodesics we argue that the insertion is at the outermost radial turning point of the corresponding geodesic. | arxiv:1910.10227 |
developing efficient gpu kernels can be difficult because of the complexity of gpu architectures and programming models. existing performance tools only provide coarse - grained suggestions at the kernel level, if any. in this paper, we describe gpa, a performance advisor for nvidia gpus that suggests potential code optimization opportunities at a hierarchy of levels, including individual lines, loops, and functions. to relieve users of the burden of interpreting performance counters and analyzing bottlenecks, gpa uses data flow analysis to approximately attribute measured instruction stalls to their root causes and uses information about a program ' s structure and the gpu to match inefficiency patterns with suggestions for optimization. to quantify each suggestion ' s potential benefits, we developed pc sampling - based performance models to estimate its speedup. our experiments with benchmarks and applications show that gpa provides an insightful report to guide performance optimization. using gpa, we obtained speedups on a volta v100 gpu ranging from 1. 01 $ \ times $ to 3. 53 $ \ times $, with a geometric mean of 1. 22 $ \ times $. | arxiv:2009.04061 |
the m - channel anderson impurity model ( m = 1, 2 ) is studied in the kondo limit with a finite voltage bias applied to the conduction electron reservoirs. using the non - crossing approximation ( nca ), we calculate the local spectral functions, the differential conductance, and susceptibility at non - zero bias for symmetric as well as asymmetric coupling of the impurity to the leads. we describe an effective procedure to solve the nca integral equations which enables us to reach temperatures far below the kondo scale. this allows us to study the scaling regime where the conductance depends on the bias only via a scaling function. our results are applicable to both tunnel junctions and to point contacts. we present a general formula which allows one to go between the two cases of tunnel junctions and point contacts. comparison is also made between the conformal field theory and the nca conduction electron self - energies in the two channel case. | arxiv:cond-mat/9707209 |
in this work we investigate the sphaleron solution in a $ su ( 2 ) \ times u ( 1 ) _ x $ gauge theory, which also encompasses the standard model, with higher scalar representation ( s ) ( $ j ^ { ( i ) }, x ^ { ( i ) } $ ). we show that the field profiles describing the sphaleron in higher scalar multiplet, have similar trends like the doublet case with respect to the radial distance. we compute the sphaleron energy and find that it scales linearly with the vacuum expectation value of the scalar field and its slope depends on the representation. we also investigate the effect of $ u ( 1 ) $ gauge field and find that it is small for the physical value of the mixing angle, $ \ theta _ { w } $ and resembles the case for the doublet. for higher representations, we show that the criterion for strong first order phase transition, $ v _ { c } / t _ { c } > \ eta $, is relaxed with respect to the doublet case, i. e. $ \ eta < 1 $. | arxiv:1409.4086 |
by separating the schr \ " odinger equation for $ n $ noninteracting spin - polarized fermions in two - dimensional hyperspherical coordinates, we demonstrate that fractional quantum hall ( fqh ) states emerge naturally from degeneracy patterns of the antisymmetric free - particle eigenfunctions. in the presence of coulomb interactions, the fqh states split off from a degenerate manifold and become observable as distinct quantized energy eigenstates with an energy gap. this alternative classification scheme is based on an approximate separability of the interacting $ n $ - fermion schr \ " odinger equation in the hyperradial coordinate, which sheds light on the emergence of laughlin states as well as other fqh states. an approximate good collective quantum number, the grand angular momentum $ k $ from $ k $ - harmonic few - body theory, is shown to correlate with known fqh states at many filling factors observed experimentally. | arxiv:1504.07884 |
learning a categorical distribution comes with its own set of challenges. a successful approach taken by state - of - the - art works is to cast the problem in a continuous domain to take advantage of the impressive performance of the generative models for continuous data. amongst them are the recently emerging diffusion probabilistic models, which have the observed advantage of generating high - quality samples. recent advances for categorical generative models have focused on log likelihood improvements. in this work, we propose a generative model for categorical data based on diffusion models with a focus on high - quality sample generation, and propose sampled - based evaluation methods. the efficacy of our method stems from performing diffusion in the continuous domain while having its parameterization informed by the structure of the categorical nature of the target distribution. our method of evaluation highlights the capabilities and limitations of different generative models for generating categorical data, and includes experiments on synthetic and real - world protein datasets. | arxiv:2303.04635 |
image registration is an ill - posed inverse problem which often requires regularisation on the solution space. in contrast to most of the current approaches which impose explicit regularisation terms such as smoothness, in this paper we propose a novel method that can implicitly learn biomechanics - informed regularisation. such an approach can incorporate application - specific prior knowledge into deep learning based registration. particularly, the proposed biomechanics - informed regularisation leverages a variational autoencoder ( vae ) to learn a manifold for biomechanically plausible deformations and to implicitly capture their underlying properties via reconstructing biomechanical simulations. the learnt vae regulariser then can be coupled with any deep learning based registration network to regularise the solution space to be biomechanically plausible. the proposed method is validated in the context of myocardial motion tracking on 2d stacks of cardiac mri data from two different datasets. the results show that it can achieve better performance against other competing methods in terms of motion tracking accuracy and has the ability to learn biomechanical properties such as incompressibility and strains. the method has also been shown to have better generalisability to unseen domains compared with commonly used l2 regularisation schemes. | arxiv:2006.04725 |
let $ h $ and $ g $ be graphs. an $ h $ - colouring of $ g $ is a proper edge - colouring $ f : e ( g ) \ rightarrow e ( h ) $ such that for any vertex $ u \ in v ( g ) $ there exists a vertex $ v \ in v ( h ) $ with $ f \ left ( \ partial _ gu \ right ) = \ partial _ hv $, where $ \ partial _ gu $ and $ \ partial _ hv $ respectively denote the sets of edges in $ g $ and $ h $ incident to the vertices $ u $ and $ v $. if $ g $ admits an $ h $ - colouring we say that $ h $ colours $ g $. the question whether there exists a graph $ h $ that colours every bridgeless cubic graph is addressed directly by the petersen colouring conjecture, which states that the petersen graph colours every bridgeless cubic graph. in 2012, mkrtchyan showed that if this conjecture is true, the petersen graph is the unique connected bridgeless cubic graph $ h $ which can colour all bridgeless cubic graphs. in this paper we extend this and show that if we were to remove all degree conditions on $ h $, every bridgeless cubic graph $ g $ can be coloured substantially only by a unique other graph : the subcubic multigraph $ s _ { 4 } $ on four vertices. a few similar results are provided also under weaker assumptions on the graph $ g $. in the second part of the paper, we also consider $ h $ - colourings of regular graphs having degree strictly greater than $ 3 $ and show that : ( i ) for any $ r > 3 $, there does not exist a connected graph $ h $ ( possibly containing parallel edges ) that colours every $ r $ - regular multigraph, and ( ii ) for every $ r > 1 $, there does not exist a connected graph $ h $ ( possibly containing parallel edges ) that colours every $ 2r $ - regular simple graph. | arxiv:2110.13684 |
spinorial methods have proven to be a powerful tool to study geometric properties of spin manifolds. our aim is to continue the spinorial study of manifolds that are not necessarily spin. we introduce and study the notion of $ g $ - invariance of spin $ ^ r $ structures on a manifold $ m $ equipped with an action of a lie group $ g $. for the case when $ m $ is a homogeneous $ g $ - space, we prove a classification result of these invariant structures in terms of the isotropy representation. as an example, we study the invariant spin $ ^ r $ structures for all the homogeneous realisations of the spheres. | arxiv:2303.05433 |
we consider the scalar - tensor theories of gravity extended by the pseudoscalar couplings to matter and gauge fields and derive constraints on the cp - odd combinations of scalar and pseudoscalar couplings from laboratory spin precession experiments and from the evolution of photon polarization over cosmological distances. we show the complimentary character of local and cosmological constraints, and derive novel bounds on the pseudoscalar couplings to photons from the laboratory experiments. it is also shown that the more accurate treatment of the spin content of nuclei used in the spin precession experiments allows to tighten bounds on lorentz - violating backgrounds coupled to the proton spin. | arxiv:0902.3217 |
visible - infrared person re - identification ( vireid ) aims to match visible and infrared pedestrian images, but the modality differences and the complexity of identity features make it challenging. existing methods rely solely on identity label supervision, which makes it difficult to fully extract high - level semantic information. recently, vision - language pre - trained models have been introduced to vireid, enhancing semantic information modeling by generating textual descriptions. however, such methods do not explicitly model body shape features, which are crucial for cross - modal matching. to address this, we propose an effective body shape - aware textual alignment ( bsata ) framework that explicitly models and utilizes body shape information to improve vireid performance. specifically, we design a body shape textual alignment ( bsta ) module that extracts body shape information using a human parsing model and converts it into structured text representations via clip. we also design a text - visual consistency regularizer ( tvcr ) to ensure alignment between body shape textual representations and visual body shape features. furthermore, we introduce a shape - aware representation learning ( srl ) mechanism that combines multi - text supervision and distribution consistency constraints to guide the visual encoder to learn modality - invariant and discriminative identity features, thus enhancing modality invariance. experimental results demonstrate that our method achieves superior performance on the sysu - mm01 and regdb datasets, validating its effectiveness. | arxiv:2504.18025 |
in glasses and other disordered materials, measurements of the vibrational density of states reveal that an excess number of long - wavelength ( low - frequency ) modes, as compared to the debye scaling seen in crystalline materials, is associated with a loss of mechanical rigidity. in this paper, we present a novel technique for measuring the density of modes ( dom ) in a real granular material, in which we mimic thermal excitations using white noise acoustic waves. the resulting vibrations are detected with piezoelectric sensors embedded inside a subset of the particles, from which we are able to compute the dom via the spectrum of the velocity autocorrelation function, a technique previously applied in thermal systems. the velocity distribution for individual particles is observed to be gaussian, but the ensemble distribution is non - gaussian due to varying widths of the individual distributions. in spite of this deviation from a true thermal system, we find that the dom exhibits several thermal - like features, including debye scaling in a compressed hexagonally ordered packing, and an increase in low - frequency modes as the confining pressure is decreased. in disordered packings, we find that a characteristic frequency $ f _ c $ increases with pressure, but more weakly than has been observed in simulations of frictionless packings. | arxiv:1209.3159 |
in this paper, we explore an idea of having newton ' s constant change its value depending on the curvature scale involved. such modification leads to a particular scalar - tensor gravity theory, with the lagrangian derived from renormalization group ( rg ) flow arguments. several of the well - known f ( r ) modified gravity models have remarkably simple description in terms of the infrared renormalization group, but not the " designer " types in general. we find that de sitter - like accelerated expansion can be generated even in the absence of cosmological constant term, entirely due to running of the newton ' s constant. in hopes of tackling the problem of cosmological constant ' s smallness, we explore the flows which are capable of generating exponential hierarchy between infrared and ultraviolet scales, and investigate cosmological evolution in the models thus derived. | arxiv:1101.4995 |
the ancillary file corrigendum. pdf contains an explanation why our proof does not work. | arxiv:1504.03872 |
rationales in the form of manually annotated input spans usually serve as ground truth when evaluating explainability methods in nlp. they are, however, time - consuming and often biased by the annotation process. in this paper, we debate whether human gaze, in the form of webcam - based eye - tracking recordings, poses a valid alternative when evaluating importance scores. we evaluate the additional information provided by gaze data, such as total reading times, gaze entropy, and decoding accuracy with respect to human rationale annotations. we compare webqamgaze, a multilingual dataset for information - seeking qa, with attention and explainability - based importance scores for 4 different multilingual transformer - based language models ( mbert, distil - mbert, xlmr, and xlmr - l ) and 3 languages ( english, spanish, and german ). our pipeline can easily be applied to other tasks and languages. our findings suggest that gaze data offers valuable linguistic insights that could be leveraged to infer task difficulty and further show a comparable ranking of explainability methods to that of human rationales. | arxiv:2402.19133 |
research on storytelling over the last 100 years has distinguished at least two levels of narrative representation ( 1 ) story, or fabula ; and ( 2 ) discourse, or sujhet. we use this distinction to create fabula tales, a computational framework for a virtual storyteller that can tell the same story in different ways through the implementation of general narratological variations, such as varying direct vs. indirect speech, character voice ( style ), point of view, and focalization. a strength of our computational framework is that it is based on very general methods for re - using existing story content, either from fables or from personal narratives collected from blogs. we first explain how a simple annotation tool allows naive annotators to easily create a deep representation of fabula called a story intention graph, and show how we use this representation to generate story tellings automatically. then we present results of two studies testing our narratological parameters, and showing that different tellings affect the reader ' s perception of the story and characters. | arxiv:1708.08585 |
in the anomaly - mediated supersymmetry ( susy ) breaking scenario, neutral gaugino of su ( 2 ) _ l multiplet, wino, can be the lightest susy particle and become a candidate for dark matter. we calculated scattering cross section of wino dark matter with nucleon, which is responsible for direct detection of the dark matter, on the assumption that the susy particles and the heavier higgs bosons have masses of the order of the gravitino mass in the susy standard model. in such a case, the wino - nucleon coupling is generated by loop processes. we have included two - loop contribution to wino - gluon interaction in the calculation, since it is one of the leading contributions to the wino - nucleon coupling. it was found that the spin - independent scattering cross section with proton is 10 ^ - ( 46 - 48 ) cm ^ 2. while it is almost independent of the wino mass, the result is quite sensitive to the higgs boson mass due to the accidental cancellation. | arxiv:1004.4090 |
cp - violating phases which contribute to the electric dipole moment ( edm ) of the neutron are considered in the context of orbifold compactificationof the heterotic string. in particular, we study the situation where cp is spontaneously broken by moduli fields acquiring, in general, complex expectation values at the minimum of duality invariant low energy effective potentials. we show, by explicit minimization of such a potential in the case of the $ { \ bf z } _ { 6 } - { \ rm iib } $ orbifold, that it is the presence of so called green - schwarz anomaly coefficients $ \ delta _ { \ rm gs } ^ { i } $, that leads to significant cp violating expectation values of the moduli. by evaluating the soft supersymmetry breaking moduli dependent $ a $ and $ b $ terms in this model, we find that the experimental bounds $ \ phi ( a ) $, $ \ phi ( b ) $ $ \ leq 5 \ times 10 ^ { - 3 } $ are exceeded for a particular range of values of the auxiliary field of the $ s $ modulus. | arxiv:hep-th/9506143 |
we show in a unified manner that the factorization method describes completely the $ l ^ 2 $ - eigenspaces associated to the discrete part of the spectrum of the twisted laplacian on constant curvature riemann surfaces. subclasses of two variable orthogonal polynomials are then derived and arise by successive derivations of elementary complex valued functions depending on the geometry of the surface. | arxiv:1003.5501 |
we develop the general framework of virtual resource distillation - - an alternative distillation strategy proposed in [ phys. rev. lett. 132, 050203 ( 2024 ) ], which extends conventional quantum resource distillation by integrating the power of classical postprocessing. the framework presented here is applicable not only to quantum states, but also dynamical quantum objects such as quantum channels and higher - order processes. we provide a general characterization and benchmarks for the performance of virtual resource distillation in the form of computable semidefinite programs as well as several operationally motivated quantities. we apply our general framework to various concrete settings of interest, including standard resource theories such as entanglement, coherence, and magic, as well as settings involving dynamical resources such as quantum memory, quantum communication, and non - markovian dynamics. the framework of probabilistic distillation is also discussed. | arxiv:2404.13048 |
using orfeus - spas ii fuv spectra, iue uv spectra, and archival euve deep survey photometry, we present a detailed picture of the behavior of the magnetic cataclysmic variable ex hydrae. like hut spectra of this source, the fuv and uv spectra reveal broad emission lines of he ii, c ii - iv, n iii and v, o vi, si iii - iv, and al iii superposed on a continuum which is blue in the uv and nearly flat in the fuv. like orfeus spectra of am her, the o vi doublet is resolved into broad and narrow emission components. consistent with its behavior in the optical, the fuv and uv continuum flux densities, the fuv and uv broad emission line fluxes, and the radial velocity of the o vi broad emission component all vary on the spin phase of the white dwarf, with the maximum of the fuv and uv continuum and broad emission line flux light curves coincident with maximum blueshift of the broad o vi emission component. on the binary phase, the broad dip in the euv light curve is accompanied by strong eclipses of the uv emission lines and by variations in both the flux and radial velocity of the o vi narrow emission component. the available data are consistent with the accretion funnel being the source of the fuv and uv continuum and the o vi broad emission component, and the white dwarf being the source of the o vi narrow emission component. | arxiv:astro-ph/9903020 |
multiple instance learning ( mil ), a powerful strategy for weakly supervised learning, is able to perform various prediction tasks on gigapixel whole slide images ( wsis ). however, the tens of thousands of patches in wsis usually incur a vast computational burden for image augmentation, limiting the mil model ' s improvement in performance. currently, the feature augmentation - based mil framework is a promising solution, while existing methods such as mixup often produce unrealistic features. to explore a more efficient and practical augmentation method, we introduce the diffusion model ( dm ) into mil for the first time and propose a feature augmentation framework called augdiff. specifically, we employ the generation diversity of dm to improve the quality of feature augmentation and the step - by - step generation property to control the retention of semantic information. we conduct extensive experiments over three distinct cancer datasets, two different feature extractors, and three prevalent mil algorithms to evaluate the performance of augdiff. ablation study and visualization further verify the effectiveness. moreover, we highlight augdiff ' s higher - quality augmented feature over image augmentation and its superiority over self - supervised learning. the generalization over external datasets indicates its broader applications. | arxiv:2303.06371 |
we develop a general formalism to describe the renormalization group flow of schur indices and fusion algebras of bps line defects in four - dimensional $ { \ cal n } = 2 $ supersymmetric quantum field theories. the formalism includes and extends known results about the seiberg - witten description of these structures. another application of the formalism is to describe the spectrum of bps partices of $ { \ mathcal n } = 2 $ gauge theories with matter in terms of the spectrum of pure $ { \ mathcal n } = 2 $ gauge theories. applications to the theory of quantum groups and to the quantization of cluster varieties are also discussed. | arxiv:2503.16685 |
detecting and classifying lesions in breast ultrasound images is a promising application of artificial intelligence ( ai ) for reducing the burden of cancer in regions with limited access to mammography. such ai systems are more likely to be useful in a clinical setting if their predictions can be explained to a radiologist. this work proposes an explainable ai model that provides interpretable predictions using a standard lexicon from the american college of radiology ' s breast imaging and reporting data system ( bi - rads ). the model is a deep neural network featuring a concept bottleneck layer in which known bi - rads features are predicted before making a final cancer classification. this enables radiologists to easily review the predictions of the ai system and potentially fix errors in real time by modifying the concept predictions. in experiments, a model is developed on 8, 854 images from 994 women with expert annotations and histological cancer labels. the model outperforms state - of - the - art lesion detection frameworks with 48. 9 average precision on the held - out testing set, and for cancer classification, concept intervention is shown to increase performance from 0. 876 to 0. 885 area under the receiver operating characteristic curve. training and evaluation code is available at https : / / github. com / hawaii - ai / bus - cbm. | arxiv:2407.00267 |
recent advances in machine learning have largely benefited from the massive accessible training data. however, large - scale data sharing has raised great privacy concerns. in this work, we propose a novel privacy - preserving data generative model based on the pate framework ( g - pate ), aiming to train a scalable differentially private data generator that preserves high generated data utility. our approach leverages generative adversarial nets to generate data, combined with private aggregation among different discriminators to ensure strong privacy guarantees. compared to existing approaches, g - pate significantly improves the use of privacy budgets. in particular, we train a student data generator with an ensemble of teacher discriminators and propose a novel private gradient aggregation mechanism to ensure differential privacy on all information that flows from teacher discriminators to the student generator. in addition, with random projection and gradient discretization, the proposed gradient aggregation mechanism is able to effectively deal with high - dimensional gradient vectors. theoretically, we prove that g - pate ensures differential privacy for the data generator. empirically, we demonstrate the superiority of g - pate over prior work through extensive experiments. we show that g - pate is the first work being able to generate high - dimensional image data with high data utility under limited privacy budgets ( $ \ epsilon \ le 1 $ ). our code is available at https : / / github. com / ai - secure / g - pate. | arxiv:1906.09338 |
the addition of a heavy charged vector gauge boson $ { \ mathbf { w } } ^ \ prime $ to the standard model ( sm ) with negligible quark couplings ( " quarkophobic " ) and triple gauge couplings can address issues with the sm, such as the b - meson anomalies and recent discrepancies in the w boson mass measurements. we present a phenomenology study probing $ { \ mathbf { w } } ^ \ prime $ production through weak boson fusion in proton - proton collisions at the large hadron collider. we operate under a simplified model with a large $ { \ mathbf { w } } ^ \ prime $ decay width and consider final states with two jets, large missing transverse momentum, and one light lepton. notably, we use point cloud learning for the first time in a bsm search $ \ unicode { x2014 } $ specifically, a novel lorentz - equivariant geometric algebra transformer $ \ unicode { x2014 } $ providing significant improvement in signal sensitivity compared to traditional methods. | arxiv:2502.16630 |
it was known that one - point functions in the abjm matrix model ( obtained by applying the localization technique to one - point functions of the half - bps wilson loop operator in the abjm theory ) satisfy the jacobi - trudi formula, which strongly indicates the integrable structure of the system. in this paper, we identify the integrable structure of two - point functions in the abjm matrix model as the two - dimensional toda lattice hierarchy. the identification implies infinitely many non - linear differential equations for the generating function of the two - point functions. | arxiv:1901.00541 |
we show that an analogue of the ( four dimensional ) image sum method can be used to reproduce the results, due to krasnikov, that for the model of a real massless scalar field on the initial globally hyperbolic region igh of two - dimensional misner space there exist two - particle and thermal hadamard states ( built on the conformal vacuum ) such that the ( expectation value of the renormalised ) stress - energy tensor in these states vanishes on igh. however, we shall prove that the conclusions of a general theorem by kay, radzikowski and wald still apply for these states. that is, in any of these states, for any point b on the cauchy horizon and any neighbourhood n of b, there exists at least one pair of non - null related points ( x, x ' ), with x and x ' in the intersection of igh with n, such that ( a suitably differentiated form of ) its two - point function is singular. ( we prove this by showing that the two - point functions of these states share the same singularities as the conformal vacuum on which they are built. ) in other words, the stress - energy tensor in any of these states is necessarily ill - defined on the cauchy horizon. | arxiv:gr-qc/9708028 |
in this paper, which is a revised version of the author ' s phd thesis, we analyze two different applications of string theory. in the first part, we focus on four dimensional compactifications of type ii string theories preserving n = 1 supersymmetry, in presence of intersecting or magnetized d - branes. we show, through world - sheet methods, how the insertion of closed string background fluxes may modify the effective interactions on dirichlet and euclidean branes. in particular, we compute flux - induced fermionic masses. the generality of our results is exploited to determine the soft terms of the action on the instanton moduli space. finally, we investigate how fluxes create new non - perturbative superpotential terms in presence of gauge and stringy instantons in sqcd - like models. the second part is devoted to the description of statistical systems through effective string models. in particular, we focus our attention on ( d - 1 ) - dimensional interfaces, present in particular statistical systems defined on compact d - dimensional spaces. we compute their exact partition function by resorting to standard covariant quantization of the nambu - goto theory, and we compare it with monte carlo data. then, we propose an effective model to describe interfaces in 2d space and test it against the dimensional reduction of the nambu - goto description of the 2d interface. | arxiv:0911.3800 |
reducing energy consumption is a challenge that is faced on a daily basis by teams from the high - performance computing as well as the embedded domain. this issue is mostly attacked from an hardware perspective, by devising architectures that put energy efficiency as a primary target, often at the cost of processing power. lately, computing platforms have become more and more heterogeneous, but the exploitation of these additional capabilities is so complex from the application developer ' s perspective that they are left unused most of the time, resulting therefore in a supplemental waste of energy rather than in faster processing times. in this paper we present a transparent, on - the - fly optimization scheme that allows a generic application to automatically exploit the available computing units to partition its computational load. we have called our approach heterogeneous platform accelerator ( hpa ). the idea is to use profiling to automatically select a computing - intensive candidate for acceleration, and then distribute the computations to the different units by off - loading blocks of code to them. using an nvidia jetson tk1 board, we demonstrate that not only hpa results in faster processing speed, but also in a considerable reduction in the total energy absorbed. | arxiv:1511.08635 |
the concept of entropy in statistical physics is related to the existence of irreversible macroscopic processes. in this work, we explore a recently introduced entropy formula for a class of stochastic processes with more than one absorbing state that is extensively used in population genetics models. we will consider the moran process as a paradigm for this class, and will extend our discussion to other models outside this class. we will also discuss the relation between non - extensive entropies in physics and epistasis ( i. e., when the effects of different alleles are not independent ) and the role of symmetries in population genetic models. | arxiv:2206.01482 |
the work we present in this paper initiated the formal study of fractional hedonic games, coalition formation games in which the utility of a player is the average value he ascribes to the members of his coalition. among other settings, this covers situations in which players only distinguish between friends and non - friends and desire to be in a coalition in which the fraction of friends is maximal. fractional hedonic games thus not only constitute a natural class of succinctly representable coalition formation games, but also provide an interesting framework for network clustering. we propose a number of conditions under which the core of fractional hedonic games is non - empty and provide algorithms for computing a core stable outcome. by contrast, we show that the core may be empty in other cases, and that it is computationally hard in general to decide non - emptiness of the core. | arxiv:1705.10116 |
the nervous system displays a variety of rhythms in both waking and sleep. these rhythms have been closely associated with different behavioral and cognitive states, but it is still unknown how the nervous system makes use of these rhythms to perform functionally important tasks. to address those questions, it is first useful to understood in a mechanistic way the origin of the rhythms, their interactions, the signals which create the transitions among rhythms, and the ways in which rhythms filter the signals to a network of neurons. this talk discusses how dynamical systems have been used to investigate the origin, properties and interactions of rhythms in the nervous system. it focuses on how the underlying physiology of the cells and synapses of the networks shape the dynamics of the network in different contexts, allowing the variety of dynamical behaviors to be displayed by the same network. the work is presented using a series of related case studies on different rhythms. these case studies are chosen to highlight mathematical issues, and suggest further mathematical work to be done. the topics include : different roles of excitation and inhibition in creating synchronous assemblies of cells, different kinds of building blocks for neural oscillations, and transitions among rhythms. the mathematical issues include reduction of large networks to low dimensional maps, role of noise, global bifurcations, use of probabilistic formulations. | arxiv:math/0305013 |
in this note we consider the problem of local classification of bonnet pairs of surfaces in 3 - dimensional minkowski space. we use split quaternions in a way similar to the use of quaternions in, arxiv : dg - ga / 9610006, for the solution in euclidean 3 - space. | arxiv:1205.0071 |
we present litmuskt - the first tool for litmus testing concurrent programs in kotlin. the tool ' s novelty also lies in the fact that kotlin is a multiplatform language, i. e., it compiles into multiple platforms, which means that the concurrency has to be tested on several of them. our tool allows writing litmus tests in a single custom dsl, and these tests are then run in kotlin / native and kotlin / jvm, two main platforms for concurrent programming in kotlin. using litmuskt, we discovered novel bugs in the kotlin compiler, which we then fixed and they are no longer present. moreover, litmuskt was integrated into the ci pipeline for kotlin. litmuskt is available on github : https : / / github. com / jetbrains - research / litmuskt. the demo is available on youtube : https : / / youtu. be / owczp _ huwss. | arxiv:2501.07472 |
for transcendental values of q the quantum tangent spaces of all left - covariant first order differential calculi of dimension less than four on the quantum group $ \ slq 2 $ are given. all such differential calculi $ \ gamma $ are determined and investigated for which the left - invariant differential one - forms $ \ omega ( u ^ 1 _ 2 ) $, $ \ omega ( u ^ 2 _ 1 ) $ and $ \ omega ( u ^ 1 _ 1 - u ^ 2 _ 2 ) $ generate $ \ gamma $ as a bimodule and the universal higher order differential calculus has the same dimension as in the classical case. important properties ( cohomology spaces, * - structures, braidings, generalized lie brackets ) of these calculi are examined as well. keywords : quantum groups, noncommutative differential calculus, quantum tangent space | arxiv:math/0006211 |
we consider a four dimensional n = 1 gauge theory with bifundamental matter and a superpotential, defined on stacks of fractional branes. by turning on a flux for the r - r graviphoton field strength and computing open string amplitudes with insertions of r - r closed string vertices, we introduce a non - anticommutative deformation and obtain the n = 1 / 2 version of the theory. we also comment on the appearance of a new structure in the effective lagrangian. | arxiv:hep-th/0502084 |
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