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in this paper, we investigate the sum - capacity of the two - user gaussian interference channel with gaussian superposition coding and successive decoding. we first examine an approximate deterministic formulation of the problem, and introduce the complementarity conditions that capture the use of gaussian coding and successive decoding. in the deterministic channel problem, we find the constrained sum - capacity and its achievable schemes with the minimum number of messages, first in symmetric channels, and then in general asymmetric channels. we show that the constrained sum - capacity oscillates as a function of the cross link gain parameters between the information theoretic sum - capacity and the sum - capacity with interference treated as noise. furthermore, we show that if the number of messages of either of the two users is fewer than the minimum number required to achieve the constrained sum - capacity, the maximum achievable sum - rate drops to that with interference treated as noise. we provide two algorithms ( a simple one and a finer one ) to translate the optimal schemes in the deterministic channel model to the gaussian channel model. we also derive two upper bounds on the sum - capacity of the gaussian han - kobayashi schemes, which automatically upper bound the sum - capacity using successive decoding of gaussian codewords. numerical evaluations show that, similar to the deterministic channel results, the constrained sum - capacity in the gaussian channels oscillates between the sum - capacity with han - kobayashi schemes and that with single message schemes. | arxiv:1103.0038 |
h - bn and ga2o3 are two promising semiconductor materials. however, the band alignment of the ga2o3 / h - bn heterojunction has not been identified, hindering device development. in this study, the heterojunction was prepared by metalorganic chemical vapor deposition and pulsed laser deposition. transmission electron microscopy confirmed sharp heterointerface and revealed structural evolution as amorphous - ga2o3 grew thicker on lattice mismatched h - bn. the valence and conduction band offsets were determined by high - resolution x - ray photoemission spectroscopy to be 1. 75 and 3. 35 - 3. 65 ev, respectively, corresponding to a type - ii heterojunction. the extremely large type - ii band offsets along with indirect bandgap of ga2o3 may be leveraged for exceptional electron confinement and storage. | arxiv:1906.06891 |
using a functional renormalization group method, we obtain the phase diagram of the two - leg ladder system within the holstein - hubbard model, which includes both electron - electron and electron - phonon interactions. our renormalization group technique allows us to analyze the problem for both weak and strong electron - phonon coupling. we show that, in contrast results from conventional weak coupling studies, electron - phonon interactions can dominate electron - electron interactions because of retardation effects. | arxiv:cond-mat/0603055 |
we present a general algorithm to show that a scattering operator associated to a semilinear dispersive equation is real analytic, and to compute the coefficients of its taylor series at any point. we illustrate this method in the case of the schrodinger equation with power - like nonlinearity or with hartree type nonlinearity, and in the case of the wave and klein - gordon equations with power nonlinearity. finally, we discuss the link of this approach with inverse scattering, and with complete integrability. | arxiv:0801.3774 |
magnetic quantum tunneling in a single molecule magnet ( smm ) has been studied in experiments that combine microwave spectroscopy with high sensitivity magnetic measurements. by monitoring spin - state populations in the presence of microwave magnetic fields, the energy splittings between low lying high spin superposition states of smm ni $ _ 4 $ ( $ s $ = 4 ) have been measured. absorption linewidths give an upper bound on the rate of decoherence. pulsed microwave experiments provide a direct measure of the spin - lattice relaxation time, which is found to be remarkably long ( $ \ sim $ sec ) and to increase with the energy splitting. | arxiv:cond-mat/0405331 |
experimental results from hera on diffractive vector meson production and their theoretical interpretation within microscopic qcd are reviewed with an emphasis on the bfkl color dipole and kt - factorization approaches. | arxiv:hep-ph/0501034 |
this paper is a comment on phys. rev. lett. 85, 1516 ( 2000 ) by a. v. uskov, a. - p. jauho, b. tromborg, j. mork, and r. lang. | arxiv:cond-mat/0512033 |
we classify all $ \ sp _ 4 ( \ mathbb { c } ) $ - rigid, quasi - unipotent local systems and show that all of them have geometric origin. furthermore, we investigate which of those having a maximal unipotent element are induced by fourth order calabi - yau operators. via this approach, we reconstruct all known calabi - yau operators inducing a $ \ sp _ 4 ( \ mathbb { c } ) $ - rigid monodromy tuple and obtain closed formulae for special solutions of them. | arxiv:1105.1136 |
though u - net has achieved tremendous success in medical image segmentation tasks, it lacks the ability to explicitly model long - range dependencies. therefore, vision transformers have emerged as alternative segmentation structures recently, for their innate ability of capturing long - range correlations through self - attention ( sa ). however, transformers usually rely on large - scale pre - training and have high computational complexity. furthermore, sa can only model self - affinities within a single sample, ignoring the potential correlations of the overall dataset. to address these problems, we propose a novel transformer module named mixed transformer module ( mtm ) for simultaneous inter - and intra - affinities learning. mtm first calculates self - affinities efficiently through our well - designed local - global gaussian - weighted self - attention ( lgg - sa ). then, it mines inter - connections between data samples through external attention ( ea ). by using mtm, we construct a u - shaped model named mixed transformer u - net ( mt - unet ) for accurate medical image segmentation. we test our method on two different public datasets, and the experimental results show that the proposed method achieves better performance over other state - of - the - art methods. the code is available at : https : / / github. com / dootmaan / mt - unet. | arxiv:2111.04734 |
we introduce a computationally efficient method based on the path integral formalism to describe defect - modified graphene. by taking into account the entire brillouin zone, our approach respects the lattice symmetry and can be used to investigate both short - range and long - range effects. the proposed method ' s key advantage is that the computational complexity does not increase with the system size, scaling, instead, with the number of defects. as a demonstration of our method, we explore the graphene - mediated rkky interaction between multiple magnetic impurities. our results concur with earlier findings by showing that the interaction strength and sign depend on various factors like impurity separation, sublattice arrangement, and system doping. we demonstrate that frustration can be introduced between the impurity spins by controlling their relative positions and that this frustration can be switched on and off by tuning the chemical potential of the system. | arxiv:2203.05741 |
the use of graphene in a form of discontinuous flakes in polymer composites limits the full exploitation of the unique properties of graphene, thus requiring high filler loadings for achieving - for example - satisfactory electrical and mechanical properties. herein centimetre - scale cvd graphene / polymer nanolaminates have been produced by using an iterative ' lift - off / float - on ' process and have been found to outperform, for the same graphene content, state - of - the - art flake - based graphene polymer composites in terms of mechanical reinforcement and electrical properties. most importantly these thin laminate materials show a high electromagnetic interference ( emi ) shielding effectiveness, reaching 60 db for a small thickness of 33 micron, and an absolute emi shielding effectiveness close to 3 * 10 ^ 5 db cm ^ 2 g ^ - 1 which is amongst the highest values for synthetic, non - metallic materials produced to date. | arxiv:2108.10016 |
forbidden patterns problems ( fpps ) are a proper generalisation of constraint satisfaction problems ( csps ). however, we show that when the input is connected and belongs to a class which has low tree - depth decomposition ( e. g. structure of bounded degree, proper minor closed class and more generally class of bounded expansion ) any fpp becomes a csp. this result can also be rephrased in terms of expressiveness of the logic mmsnp, introduced by feder and vardi in relation with csps. our proof generalises that of a recent paper by nesetril and ossona de mendez. note that our result holds in the general setting of problems over arbitrary relational structures ( not just for graphs ). | arxiv:0904.2521 |
we formulate the notion of an isomorphism of gkm graphs. we then show that two gkm graphs have isomorphic graph equivariant cohomology algebras if and only if the graphs are isomorphic. | arxiv:1710.08264 |
we present near - infrared imaging and spectroscopic high spatial resolution observations of the smc region n88 containing the bright, excited, extincted and compact h ii region n88a of size ~ 1 pc. to investigate its stellar content and reddening, n88 was observed using spectroscopy and imagery in the jhks - and l ' - band at a spatial resolution of ~ 0. 1 - 0. 3 ", using the vlt ut4 equipped with the naos adaptive optics system. in order to attempt to establish if the origin of the infra - red ( ir ) excess is due to bright nebulosity, circumstellar material and / or local dust, we used ks vs j - k colour - magnitude ( cm ) and jhk colour - colour ( cc ) diagrams, as well as l ' imagery. our ir - data reveal in the n88 area an ir - excess fraction of geq 30 per cent of the detected stars, as well as an unprecedently detailed morphology of n88a. it consists of an embedded cluster of ~ 3. 5 " ( ~ 1 pc ) in diameter, of at least thirteen resolved stars superposed with an unusual bright continuum centered on a very bright star. the four brightest stars in this cluster lie red - ward of h - k geq 0. 45 mag, and could be classified as young stellar object ( yso ) candidates. four other probable yso candidates are also detected in n88 along a south - north bow - shaped thin h2 filament at ~ 7 " east of the young central bright star. at 0. 2 " east of this star, a heavily embedded core is detected that could be a massive class i protostar candidate. the 2. 12 mu h2 image of n88a resembles a shell of diameter ~ 3 " ~ 0. 9 pc ) centered on the bright star. the line ratios of h2 2 - 1 s ( 1 ) and 1 - 0 s ( 0 ) relative to 1 - 0 s ( 1 ), as well as the presence of high v lines, are indicative of photodissociation regions, rather than shocks. | arxiv:0911.5490 |
we study numerically anderson localization on lattices that are tree - like except for the presence of one loop of varying length $ l $. the resulting expressions allow us to compute corrections to the bethe lattice solution on i ) random - regular - graph ( rrg ) of finite size $ n $ and ii ) euclidean lattices in finite dimension. in the first case we show that the $ 1 / n $ corrections to to the average values of observables such as the typical density of states and the inverse participation ratio have prefactors that diverge exponentially approaching the critical point, which explains the puzzling observation that the numerical simulations on finite rrgs deviate spectacularly from the expected asymptotic behavior. in the second case our results, combined with the $ m $ - layer expansion, predict that corrections destroy the exotic critical behavior of the bethe lattice solution in any finite dimension, strengthening the suggestion that the upper critical dimension of anderson localization is infinity. this approach opens the way to the computation of non - mean - field critical exponents by resumming the series of diverging diagrams through the same recipes of the field - theoretical perturbative expansion. | arxiv:2304.10365 |
in this study, we present the bicubic hermite element method ( bhem ), a new computational framework devised for the elastodynamic simulation of parametric thin - shell structures. the bhem is constructed based on parametric quadrilateral hermite patches, which serve as a unified representation for shell geometry, simulation, collision avoidance, as well as rendering. compared with the commonly utilized linear fem, the bhem offers higher - order solution spaces, enabling the capture of more intricate and smoother geometries while employing significantly fewer finite elements. in comparison to other high - order methods, the bhem achieves conforming $ \ mathcal { c } ^ 1 $ continuity for kirchhoff - love ( kl ) shells with minimal complexity. furthermore, by leveraging the subdivision and convex hull properties of hermite patches, we develop an efficient algorithm for ray - patch intersections, facilitating collision handling in simulations and ray tracing in rendering. this eliminates the need for laborious remodeling of the pre - existing parametric surface as the conventional approaches do. we substantiate our claims with comprehensive experiments, which demonstrate the high accuracy and versatility of the proposed method. | arxiv:2312.14839 |
we consider diagonal and non - diagonal qcd sum rules for the ground state heavy baryons to leading order in $ 1 / m _ q $ and at next - to - leading order in $ \ alpha _ s $. in the non - diagonal case we evaluate the eight different two - loop diagrams which determine the perturbative $ \ alpha _ s $ - corrections to the wilson coefficient of the quark condensate in the operator product expansion. the qcd corrections to the non - diagonal sum rules are moderate compared to the qcd corrections in the diagonal case. we also consider constituent type sum rules using constituent type interpolating currents. the obtained results are in reasonable agreement with the corresponding results obtained in the diagonal case. as central values for the bound state energies we find $ m ( \ lambda _ q ) - m _ q = 760 mev $ and $ m ( \ sigma _ q ) - m _ q = 940 mev $. the central values for the residues are given by $ f ( \ lambda _ q ) = 0. 030 gev ^ 3 $ and $ f ( \ sigma _ q ) = 0. 038 gev ^ 3 $. | arxiv:hep-ph/9705447 |
we consider a discrete - time binary branching random walk with independent standard normal increments subject to a penalty $ \ b $ for every pair of particles that get within distance $ \ e $ of each other at any time. we give a precise description of the most likely configurations of the particles under this law for $ n $ large and $ \ b, \ e $ fixed. particles spread out over a distance $ 2 ^ { 2n / 3 } $, essentially in finite time, and subsequently arrange themselves so that at time $ 2n / 3 $ they cover a grid of width $ \ e $ with one particle per site. after time $ 2n / 3 $, the bulk of the particles and their descendants do not move anymore, while the particles in a boundary layer of width $ 2 ^ { n / 3 } $ form a ` ` staircase " to the particles in the bulk. at time $ n $, each site in the boundary layer is occupied by $ 2 ^ { n / 3 } $ particles. | arxiv:2407.15533 |
in this paper we prove that any strongly embedded subgroup of a k * - group g of finite morley rank and odd type that does not interpret any bad field is solvable if its pruefer 2 - rank is at least 2. if the normal 2 - rank of g is at least 3 this has two important consequences : if g contains a non - solvable centraliser of an involution, then g does not contain any proper 2 - generated core and centralisers of involutions have trivial cores. | arxiv:math/9811163 |
the concept of integrable boundary conditions is applied to hydrodynamic type systems. examples of such boundary conditions for dispersionless toda systems are obtained. the close relation of integrable boundary conditions with integrable reductions of multi - field systems is observed. the problem of consistency of boundary conditions with the hamiltonian formulation is discussed. examples of hamiltonian integrable hydrodynamic type systems on a segment and a semi - line are presented. | arxiv:0805.3828 |
we present two quantum algorithms based on evolution randomization, a simple variant of adiabatic quantum computing, to prepare a quantum state $ \ vert x \ rangle $ that is proportional to the solution of the system of linear equations $ a \ vec { x } = \ vec { b } $. the time complexities of our algorithms are $ o ( \ kappa ^ 2 \ log ( \ kappa ) / \ epsilon ) $ and $ o ( \ kappa \ log ( \ kappa ) / \ epsilon ) $, where $ \ kappa $ is the condition number of $ a $ and $ \ epsilon $ is the precision. both algorithms are constructed using families of hamiltonians that are linear combinations of products of $ a $, the projector onto the initial state $ \ vert b \ rangle $, and single - qubit pauli operators. the algorithms are conceptually simple and easy to implement. they are not obtained from equivalences between the gate model and adiabatic quantum computing. they do not use phase estimation or variable - time amplitude amplification, and do not require large ancillary systems. we discuss a gate - based implementation via hamiltonian simulation and prove that our second algorithm is almost optimal in terms of $ \ kappa $. like previous methods, our techniques yield an exponential quantum speedup under some assumptions. our results emphasize the role of hamiltonian - based models of quantum computing for the discovery of important algorithms. | arxiv:1805.10549 |
a maximally supersymmetric configuration of super yang - mills living on a noncommutative torus corresponds to a constant curvature connection. on a noncommutative toroidal orbifold there is an additional constraint that the connection be equivariant. we study moduli spaces of ( equivariant ) constant curvature connections on noncommutative even - dimensional tori and on toroidal orbifolds. as an illustration we work out the cases of z _ { 2 } and z _ { 4 } orbifolds in detail. the results we obtain agree with a commutative picture describing systems of branes wrapped on cycles of the torus and branes stuck at exceptional orbifold points. | arxiv:hep-th/0005174 |
excitons in semiconductors are usually non interacting and behave like an ideal gas, but may condense to a strongly correlated liquid like state, i. e. electron hole liquid ( ehl ), at high density and appropriate temperature. ehl is a macroscopic quantum state with exotic properties and represents the ultimate attainable charge excitation density in steady states. it bears great promise for a variety of fields such as ultrahigh power photonics and quantum science and technology. however, the condensation of gas like excitons to ehl has often been restricted to cryogenic temperatures, which significantly limits the prospect of ehl for use in practical applications. herein we demonstrate the formation of ehl at room temperature in monolayer mos2 by taking advantage of the monolayer ' s extraordinarily strong exciton binding energy. this work demonstrates the potential for the liquid like state of charge excitations to be a useful platform for the studies of macroscopic quantum phenomena and the development of optoelectronic devices. | arxiv:1710.09538 |
in this paper we generalize kaplansky ' s combinatorial characterization of the isomorphism types of embeddings of a cyclic subgroup in a finite abelian group given in his 1951 book ` ` infinite abelian groups ' '. for this we introduce partial maps on littlewood - richardson tableaux and show that they characterize the isomorphism types of finite direct sums of such cyclic embeddings. | arxiv:1905.05688 |
the persistent issue of human bias in recruitment processes poses a formidable challenge to achieving equitable hiring practices, particularly when influenced by demographic characteristics such as gender and race of both interviewers and candidates. asynchronous video interviews ( avis ), powered by artificial intelligence ( ai ), have emerged as innovative tools aimed at streamlining the application screening process while potentially mitigating the impact of such biases. these ai - driven platforms present an opportunity to customize the demographic features of virtual interviewers to align with diverse applicant preferences, promising a more objective and fair evaluation. despite their growing adoption, the implications of virtual interviewer identities on candidate experiences within avis remain underexplored. we aim to address this research and empirical gap in this paper. to this end, we carried out a comprehensive between - subjects study involving 218 participants across six distinct experimental conditions, manipulating the gender and skin color of an ai virtual interviewer agent. our empirical analysis revealed that while the demographic attributes of the agents did not significantly influence the overall experience of interviewees, variations in the interviewees ' demographics significantly altered their perception of the avi process. further, we uncovered that the mediating roles of social presence and perception of the virtual interviewer critically affect interviewees ' perceptions of fairness ( + ), privacy ( - ), and impression management ( + ). | arxiv:2408.14159 |
the present work introduces a robust way to generate attosecond pulses with tunable ellipticity via high - order harmonic generation by co - rotating $ \ omega - 2 \ omega $ bicircular laser fields. the total electric field of the laser fields exhibits an absence of rotational symmetry, which leads to the generation of high harmonics of the same helicity across a broad range of spectral bandwidth. high - harmonics with the same helicity offer the opportunity to synthesize attosecond pulses with tunable ellipticity. the polarisation properties of the generated harmonics are robust against the variations in driving fields ' parameters, such as wavelength, intensity ratio, and the sub - cycle phase between $ \ omega - 2 \ omega $ fields. our work opens an avenue to study chiral - sensitive light - matter ultrafast processes on their intrinsic timescale. | arxiv:2305.00513 |
video recommender systems ( rss ) have gained increasing attention in recent years. existing mainstream rss focus on optimizing the matching function between users and items. however, we noticed that users frequently encounter playback issues such as slow loading or stuttering while browsing the videos, especially in weak network conditions, which will lead to a subpar browsing experience, and may cause users to leave, even when the video content and recommendations are superior. it is quite a serious issue, yet easily overlooked. to tackle this issue, we propose an on - device gating and ranking framework ( grf ) that cooperates with server - side rs. specifically, we utilize a gate model to identify videos that may have playback issues in real - time, and then we employ a ranking model to select the optimal result from a locally - cached pool to replace the stuttering videos. our solution has been fully deployed on kwai, a large - scale short video platform with hundreds of millions of users globally. moreover, it significantly enhances video playback performance and improves overall user experience and retention rates. | arxiv:2410.05863 |
we conduct experiments with flexible swimmers to address the impact of fluid viscoelasticity on their locomotion. the swimmers are composed of a magnetic head actuated in rotation by a frequency - controlled magnetic field and a flexible tail whose deformation leads to forward propulsion. we consider both viscous newtonian and glucose - based boger fluids with similar viscosities. we find that the elasticity of the fluid systematically enhances the locomotion speed of the swimmer, and that this enhancement increases with deborah number. using particle image velocimetry to visualize the flow field, we find a significant difference in the amount of shear between the rear and leading parts of the swimmer head. we conjecture that viscoelastic normal stresses lead to a net elastic forces in the swimming direction and thus a faster swimming speed. | arxiv:1303.3944 |
a fast consistency prover is a consistent poly - time axiomatized theory that has short proofs of the finite consistency statements of any other poly - time axiomatized theory. kraj \ ' \ i \ v { c } ek and pudl \ ' ak proved that the existence of an optimal propositional proof system is equivalent to the existence of a fast consistency prover. it is an easy observation that $ { \ sf np } = { \ sf conp } $ implies the existence of a fast consistency prover. the reverse implication is an open question. in this paper we define the notion of an unlikely fast consistency prover and prove that its existence is equivalent to $ { \ sf np } = { \ sf conp } $. next it is proved that fast consistency provers do not exist if one considers re axiomatized theories rather than theories with an axiom set that is recognizable in polynomial time. | arxiv:2004.05431 |
closed form expressions for the domination number of an $ n \ times m $ grid have attracted significant attention, and an exact expression has been obtained in 2011 by gon \ c { c } alves et al. in this paper, we present our results on obtaining new lower bounds on the connected domination number of an $ n \ times m $ grid. the problem has been solved for grids with up to $ 4 $ rows and with $ 6 $ rows by tolouse et al and the best currently known lower bound for arbitrary $ m, n $ is $ \ lceil \ frac { mn } { 3 } \ rceil $. fujie came up with a general construction for a connected dominating set of an $ n \ times m $ grid of size $ \ min \ left \ { 2n + ( m - 4 ) + \ lfloor \ frac { m - 4 } { 3 } \ rfloor ( n - 2 ), 2m + ( n - 4 ) + \ lfloor \ frac { n - 4 } { 3 } \ rfloor ( m - 2 ) \ right \ } $. in this paper, we investigate whether this construction is indeed optimum. we prove a new lower bound of $ \ left \ lceil \ frac { mn + 2 \ lceil \ frac { \ min \ { m, n \ } } { 3 } \ rceil } { 3 } \ right \ rceil $ for arbitrary $ m, n \ geq 4 $. | arxiv:2011.11328 |
this paper focuses on the problem of distributed consensus control of multi - agent systems while considering two main practical concerns ( i ) stochastic noise in the agent dynamics and ( ii ) predefined performance constraints over evolutions of multi - agent systems. in particular, we consider that each agent is driven by a stochastic differential equation with state - dependent noise which makes the considered problem more challenging compared to non - stochastic agents. the work provides sufficient conditions under which the proposed timevarying distributed control laws ensure consensus in expectation and almost sure consensus of stochastic multi - agent systems while satisfying prescribed performance constraints over evolutions of the systems in the sense of the qth moment. finally, we demonstrate the effectiveness of the proposed results with a numerical example. | arxiv:2203.03665 |
we determine versal non - commutative deformations of some simple collections in the categories of perverse coherent sheaves arising from tilting generators for projective morphisms. | arxiv:1806.04858 |
despite its scientific, political, and practical value, comprehensive information about human languages, in all their variety and complexity, is not readily obtainable and searchable. one reason is that many language data are collected as audio and video recordings which imposes a challenge to document indexing and retrieval. annotation of multimedia data provides an opportunity for making the semantics explicit and facilitates the searching of multimedia documents. we have developed ontoelan, an ontology - based linguistic multimedia annotator that features : ( 1 ) support for loading and displaying ontologies specified in owl ; ( 2 ) creation of a language profile, which allows a user to choose a subset of terms from an ontology and conveniently rename them if needed ; ( 3 ) creation of ontological tiers, which can be annotated with profile terms and, therefore, corresponding ontological terms ; and ( 4 ) saving annotations in the xml format as multimedia ontology class instances and, linked to them, class instances of other ontologies used in ontological tiers. to our best knowledge, ontoelan is the first audio / video annotation tool in linguistic domain that provides support for ontology - based annotation. | arxiv:0902.3026 |
the fundamental plane ( fp ) is an empirical relation between the size, surface brightness, and velocity dispersion of early - type galaxies. this relation has been studied extensively for early - type galaxies in the local universe to constrain galaxy formation mechanisms. the evolution of the zeropoint of this plane has been extended to high redshifts to study the luminosity evolution of massive galaxies, under the assumption of structural homology. in this work, we assess this assumption by replacing surface brightness with stellar mass density and present the evolution of the " mass fp " for massive, quiescent galaxies since z ~ 2. by accounting for stellar populations, we thereby isolate and trace structural and dynamical evolution. despite the observed dramatic evolution in the sizes and morphologies of massive galaxies since z ~ 3, we find that quiescent galaxies lie on the mass fp out to z ~ 2. in contrast with ~ 1. 4 dex evolution in the luminosity fp, average residuals from the z ~ 0 mass fp are less than ~ 0. 15 dex since z ~ 2. assuming the hyde & bernardi ( 2009 ) mass fp slope, we find that this minimal offset scales as ( 1 + z ) ^ { - 0. 095 + / - 0. 043 }. this result lends credence to previous studies that derived luminosity evolution from the fp. therefore, despite their compact sizes and suggestions that massive galaxies are more disk - like at z ~ 2, the relationship between their dynamics and structural properties are consistent with local early - type galaxies. finally, we find no strong evidence for a tilt of the mass fp relative to the virial plane, but emphasize the need for full models including selection biases to fully investigate this issue. | arxiv:1309.6638 |
this paper examines information - theoretic questions regarding the difficulty of compressing data versus the difficulty of decompressing data and the role that information loss plays in this interaction. finite - state compression and decompression are shown to be of equivalent difficulty, even when the decompressors are allowed to be lossy. inspired by kolmogorov complexity, this paper defines the optimal * decompression * ratio achievable on an infinite sequence by finite - state decompressors ( that is, finite - state transducers outputting the sequence in question ). it is shown that the optimal compression ratio achievable on a sequence s by any * information lossless * finite state compressor, known as the finite - state dimension of s, is equal to the optimal decompression ratio achievable on s by any finite - state decompressor. this result implies a new decompression characterization of finite - state dimension in terms of lossy finite - state transducers. | arxiv:cs/0609096 |
transformer - based models have achieved great success in various nlp, vision, and speech tasks. however, the core of transformer, the self - attention mechanism, has a quadratic time and memory complexity with respect to the sequence length, which hinders applications of transformer - based models to long sequences. many approaches have been proposed to mitigate this problem, such as sparse attention mechanisms, low - rank matrix approximations and scalable kernels, and token mixing alternatives to self - attention. we propose a novel pooling network ( ponet ) for token mixing in long sequences with linear complexity. we design multi - granularity pooling and pooling fusion to capture different levels of contextual information and combine their interactions with tokens. on the long range arena benchmark, ponet significantly outperforms transformer and achieves competitive accuracy, while being only slightly slower than the fastest model, fnet, across all sequence lengths measured on gpus. we also conduct systematic studies on the transfer learning capability of ponet and observe that ponet achieves 95. 7 % of the accuracy of bert on the glue benchmark, outperforming fnet by 4. 5 % relative. comprehensive ablation analysis demonstrates effectiveness of the designed multi - granularity pooling and pooling fusion for token mixing in long sequences and efficacy of the designed pre - training tasks for ponet to learn transferable contextualized language representations. | arxiv:2110.02442 |
text - based games are a popular testbed for language - based reinforcement learning ( rl ). in previous work, deep q - learning is commonly used as the learning agent. q - learning algorithms are challenging to apply to complex real - world domains due to, for example, their instability in training. therefore, in this paper, we adapt the soft - actor - critic ( sac ) algorithm to the text - based environment. to deal with sparse extrinsic rewards from the environment, we combine it with a potential - based reward shaping technique to provide more informative ( dense ) reward signals to the rl agent. we apply our method to play difficult text - based games. the sac method achieves higher scores than the q - learning methods on many games with only half the number of training steps. this shows that it is well - suited for text - based games. moreover, we show that the reward shaping technique helps the agent to learn the policy faster and achieve higher scores. in particular, we consider a dynamically learned value function as a potential function for shaping the learner ' s original sparse reward signals. | arxiv:2302.10720 |
silicon can be isotopically enriched, allowing for the fabrication of highly coherent semiconductor spin qubits. however, the conduction band of bulk si exhibits a six - fold valley degeneracy, which may adversely impact the performance of silicon quantum devices. to date, the spatial characterization of valley states in si remains limited. moreover, techniques for probing valley states in functional electronic devices are needed. we describe here a cryogen - free scanning gate microscope for the characterization of si / si $ _ { 0. 7 } $ ge $ _ { 0. 3 } $ quantum devices at mk temperatures. the microscope is based on the pan - walker design, with coarse positioning piezo stacks and a fine scanning piezo tube. a tungsten microscope tip is attached to a tuning fork for active control of the tip - to - sample distance. to reduce vibration noise from the pulse tube cooler, we utilize both active and passive vibration isolation mechanisms, and achieve a root - mean - square noise in $ z $ of $ \ sim $ 2 nm. our microscope is designed to characterize fully functioning si / si $ _ { 0. 7 } $ ge $ _ { 0. 3 } $ quantum devices. as a proof of concept, we use the microscope to manipulate the charge occupation of a si quantum dot, opening up a range of possibilities for the exploration of quantum devices and materials. | arxiv:2105.05684 |
the health threat from sars - cov - 2 airborne infection has become a public emergency of international concern. during the ongoing coronavirus pandemic, people have been advised by the centers for disease control and prevention to maintain social distancing of at least 2 m to limit the risk of exposure to the coronavirus. experimental data, however, show that infected aerosols and droplets trapped inside a turbulent puff cloud can travel up to 7 to 8 m. we propose a nuclear physics analogy - based modeling of the complex gas cloud and its payload of pathogen - virions. we show that the cloud stopping range is proportional to the product of the puff ' s diameter and its density. we use our puff model to determine the average density of the buoyant fluid in the turbulent cloud. a fit to the experimental data yields $ 1. 8 < \ rho _ p / \ rho _ { \ rm air } < 4. 0 $, where $ \ rho _ p $ and $ \ rho _ { \ rm air } $ are the average density of the puff and the air. we demonstrate that temperature variation could cause an $ { \ cal o } ( \ pm 8 \ % ) $ effect in the puff stopping range for extreme ambient cold or warmth. we also demonstrate that aerosols and droplets can remain suspended for hours in the air. therefore, once the puff slows down sufficiently, and its coherence is lost, the eventual spreading of the infected aerosols becomes dependent on the ambient air currents and turbulence. | arxiv:2007.05410 |
this paper studies a boltzmann - nordheim equation in a slab with two - dimensional velocity space and pseudo - maxwellian forces. strong solutions are obtained for the cauchy problem with large initial data in an $ l ^ 1 \ cap l ^ { \ infty } $ setting. the main results are existence, uniqueness, and stability of solutions conserving mass, momentum, and energy. the solutions either explode in the $ l ^ \ infty $ - norm in finite time, or exist globally in time. they are obtained as limits of solutions to corresponding anyon equations. | arxiv:1601.06927 |
given $ n \ geq 2 $, we completely classify the solutions of the anisotropic $ n $ - liouville equation $ $ - \ delta _ n ^ h \, u = e ^ u \ quad \ text { in } \ mathbb { r } ^ n, $ $ under the finite mass condition $ \ int _ { \ mathbb { r } ^ n } e ^ u \, dx < + \ infty $. here $ \ delta _ n ^ h $ is the so - called finsler $ n $ - laplacian induced by a positively homogeneous function $ h $. as a consequence for $ n = 2 $, we give an affirmative answer to a conjecture made in [ g. wang and c. xia, j. differential equations 252 ( 2012 ) 1668 - - 1700 ]. | arxiv:2306.12039 |
time - to - digital converters ( tdcs ) are used in various fields, including high - energy physics. one advantage of implementing tdcs in field - programmable gate arrays ( fpgas ) is the flexibility on the modification of the logics, which is useful to cope with the changes in the experimental conditions. recent fpgas make it possible to implement tdcs with a time resolution less than 10 ps. on the other hand, various drift chambers require a time resolution of o ( 0. 1 ) ns, and a simple and easy - to - implement tdc is useful for a robust operation. herein an eight - channel tdc with a variable bin size down to 0. 28 ns is implemented in a xilinx kintex - 7 fpga and tested. the tdc is based on a multisampling scheme with quad phase clocks synchronised with an external reference clock. calibration of the bin size is unnecessary if a stable reference clock is available, which is common in high - energy physics experiments. depending on the channel, the standard deviation of the differential nonlinearity for a 0. 28 ns bin size is 0. 13 - 0. 31. the performance has a negligible dependence on the temperature. the power consumption and the potential to extend the number of channels are also discussed. | arxiv:1701.05375 |
a commonly accepted view is that stable single bubble sonoluminescence ( sbsl ) can only be achieved in the presence of a noble gas or hydrogen. in air - seeded bubbles, the content of diatomic gasses is burned off to leave the small amount of argon needed to sustain stable operation. here we report that long term stable sbsl can be sustained with only nitrogen, oxygen, or nitrogen / oxygen mixtures being present. compared to that of a stable argon bubble, the emission is much weaker and the spectrum looks much colder. oscillating states as well as recycling states are also observed. an intriguing saturation effect seems connected with the presence of water vapor in the bubble. | arxiv:physics/0604160 |
understanding the electronic transport properties of iron under high temperatures and pressures is essential for constraining geophysical processes. the difficulty of reliably measuring these properties under earth - core conditions calls for sophisticated theoretical methods that can support diagnostics. we present results of the electrical conductivity within the pressure and temperature ranges found in earth ' s core from simulating microscopic ohm ' s law using time - dependent density functional theory. our predictions provide a new perspective on resolving discrepancies in recent experiments. | arxiv:2203.06025 |
it is shown that the two - flavor neutrino oscillation equations admit an exact analytic solution for arbitrarily chosen normalized electron neutrino population, provided the electron plasma density is adjusted in a certain way. the associated formula for the electron plasma density is applied to the cases of exponentially decaying or oscillating electron neutrino populations. | arxiv:1307.8141 |
dwarf galaxies like sagittarius ( sgr ) provide a unique window into the early stages of galactic chemical evolution, particularly through their metal - poor stars. by studying the chemical abundances of stars in the sgr core and tidal streams, we can gain insights into the assembly history of this galaxy and its early heavy element nucleosynthesis processes. we efficiently selected extremely metal - poor candidates in the core and streams for high - resolution spectroscopic analysis using metallicity - sensitive photometry from skymapper dr2, and gaia dr3 xp spectra and proper motions. this allowed us to obtain a high - purity selection of sgr members based on stellar kinematics while reducing the chances of potential contamination from the milky way halo. we present a sample of 37 sgr stars with detailed chemical abundances, of which we identify 10 extremely metal - poor ( emp ; $ \ rm { [ fe / h ] } \ le - 3. 0 $ ) stars, 25 very metal - poor ( vmp ; $ \ rm { [ fe / h ] } \ le - 2. 0 $ ) stars, and 2 metal - poor ( mp ; $ \ rm { [ fe / h ] } \ le - 1. 0 $ ) stars. this sample increases the number of extremely metal - poor sgr stars analyzed with high - resolution spectroscopy by a factor of five. of these stars, 15 are identified as members of the sgr tidal stream, while the remaining 22 are associated with the core. we derive abundances for up to 20 elements and identify no statistically significant differences between the element abundance patterns across the core and stream samples. intriguingly, we identify stars that may have formed in ultra - faint dwarf galaxies that accreted onto sgr, in addition to patterns of c and r - process elements distinct from the milky way halo. over half of the sample shows a neutron - capture element abundance pattern consistent with the scaled solar pure r - process pattern, indicating early r - process enrichment in the sgr progenitor. | arxiv:2501.14061 |
in connection with generalized cluster algebras we introduce a certain generalization of the celebrated rogers dilogarithm, which we call the rogers dilogarithms of higher degree. we show that there is an identity of these generalized rogers dilogarithms associated with any period of seeds of a generalized cluster algebra. | arxiv:1605.04777 |
we study the following boundary value problem with a concave - convex nonlinearity : \ begin { equation * } \ left \ { \ begin { array } { r c l l } - \ delta _ p u & = & \ lambda \, u ^ { q - 1 } + u ^ { r - 1 } & \ textrm { in } \ omega, \ \ u & = & 0 & \ textrm { on } \ partial \ omega. \ end { array } \ right. \ end { equation * } here $ \ omega \ subset \ mathbb { r } ^ n $ is a bounded domain and $ 1 < q < p < r < p ^ * $. it is well known that there exists a number $ \ lambda _ { q, r } > 0 $ such that the problem admits at least two positive solutions for $ 0 < \ lambda < \ lambda _ { q, r } $, at least one positive solution for $ \ lambda = \ lambda _ { q, r } $, and no positive solution for $ \ lambda > \ lambda _ { q, r } $. we show that \ [ \ lim _ { q \ to p } \ lambda _ { q, r } = \ lambda _ 1 ( p ), \ ] where $ \ lambda _ 1 ( p ) $ is the first eigenvalue of the p - laplacian. it is worth noticing that $ \ lambda _ 1 ( p ) $ is the threshold for existence / nonexistence of positive solutions to the above problem in the limit case $ q = p $. | arxiv:1405.0621 |
we consider a local moment which is coupled by a non - random kondo $ j $ to a band of conduction electrons in a random potential. we prove an analog of anderson ' s theorem in a large - n limit of this model. the theorem states that when the disorder is weak, the disorder - averaged low - temperature thermodynamics is independent of the strength of the disorder ; remarkably, it further states that fluctuation effects in the long - time limit are { \ it independent even of the realization of the disorder }. we discuss the relationship of this theorem to theoretical and experimental studies of similar problems. | arxiv:cond-mat/9911441 |
in the present work, we analyze the evolution of the scalar and tensorial perturbations and the quantities relevant for the physical description of the universe, as the density contrast of the scalar perturbations and the gravitational waves energy density during the bose - einstein condensation of dark matter. the behavior of these parameters during the bose - einstein phase transition of dark matter is analyzed in details. to study the cosmological dynamics and evolution of scalar and tensorial perturbations in a universe with and without cosmological constant we use both analytical and numerical methods. the bose - einstein phase transition modifies the evolution of gravitational waves of cosmological origin, as well as the process of large - scale structure formation. | arxiv:1211.6701 |
in the current context where online platforms have been effectively weaponized in a variety of geo - political events and social issues, internet memes make fair content moderation at scale even more difficult. existing work on meme classification and tracking has focused on black - box methods that do not explicitly consider the semantics of the memes or the context of their creation. in this paper, we pursue a modular and explainable architecture for internet meme understanding. we design and implement multimodal classification methods that perform example - and prototype - based reasoning over training cases, while leveraging both textual and visual sota models to represent the individual cases. we study the relevance of our modular and explainable models in detecting harmful memes on two existing tasks : hate speech detection and misogyny classification. we compare the performance between example - and prototype - based methods, and between text, vision, and multimodal models, across different categories of harmfulness ( e. g., stereotype and objectification ). we devise a user - friendly interface that facilitates the comparative analysis of examples retrieved by all of our models for any given meme, informing the community about the strengths and limitations of these explainable methods. | arxiv:2212.05612 |
we prove that any smooth irreducible supersingular representation with central character of $ \ text { gl } _ 2 ( f ) $ is never of finite presentation when $ f $ is a finite field extension of $ \ mathbb { q } _ p $ such that $ f \ neq \ mathbb { q } _ p $, extending a result of schraen for quadratic extensions. | arxiv:1911.12030 |
we treat the nonequilibrium motion of a single impurity atom in a low - temperature single - species fermi sea, interacting via a contact interaction. in the nonequilibrium regime, the impurity does a superdiffusive geometric random walk where the typical distance traveled grows with time as $ \ sim t ^ { d / ( d + 1 ) } $ for the $ d $ - dimensional system with $ d \ geq 2 $. for nonzero temperature $ t $, this crosses over to diffusive motion at long times with diffusivity $ d \ sim t ^ { - ( d - 1 ) / 2 } $. these results apply also to a nonzero concentration of impurity atoms as long as they remain dilute and nondegenerate. | arxiv:1201.1055 |
we investigate charge relaxation rates due to acoustic phonons in weakly - confined quantum dot systems, including both deformation potential and piezoelectric field interactions. single - electron excited states lifetimes are calculated for single and coupled quantum dot structures, both in homonuclear and heteronuclear devices. piezoelectric field scattering is shown to be the dominant relaxation mechanism in many experimentally relevant situations. on the other hand, we show that appropriate structure design allows to minimize separately deformation potential and piezolectric field interactions, and may bring electron lifetimes in the range of microseconds. | arxiv:cond-mat/0604655 |
the nuclear shadowing and antishadowing effects are explained by a unitarized bfkl equation. the $ q ^ 2 $ - and $ x $ - variations of the nuclear parton distributions are detailed based on the level of the unintegrated gluon distribution. in particular, the asymptotical behavior of the unintegrated gluon distribution near the saturation limit in nuclear targets is studied. our results in the nuclear targets are insensitive to the input distributions if the parameters are fixed by the data of a free proton. | arxiv:0801.3349 |
within the blazar population, hard x - ray selected objects are of particular interest as they tend to lie at each end of the blazar sequence. in particular, flat spectrum radio quasars located at high redshifts display the most powerful jets, the largest black hole masses and the most luminous accretion disks : their spectral energy distribution has a compton peak in the sub - mev region which favours their detection by instruments like integral / ibis and swift / bat. these sources are even more extreme than blazars selected in other wavebands, like, for example, the gamma - ray range explored by fermi. here we report on a sample of 12 high redshift blazars detected so far by integral, including 3 newly identified objects. some properties of the combined ibis / bat sample of high redshift blazars ( z > 2 ) are also compared to those of a similar similar sample obtained by fermi. | arxiv:1302.2447 |
let $ l $ be a second order elliptic operator on $ r ^ d $ with a constant diffusion matrix and a dissipative ( in a weak sense ) drift $ b \ in l ^ p _ { loc } $ with some $ p > d $. we assume that $ l $ possesses a lyapunov function, but no local boundedness of $ b $ is assumed. it is known that then there exists a unique probability measure $ \ mu $ satisfying the equation $ l ^ * \ mu = 0 $ and that the closure of $ l $ in $ l ^ 1 ( \ mu ) $ generates a markov semigroup $ \ { t _ t \ } _ { t \ ge 0 } $ with the resolvent $ \ { g _ \ lambda \ } _ { \ lambda > 0 } $. we prove that, for any lipschitzian function $ f \ in l ^ 1 ( \ mu ) $ and all $ t, \ lambda > 0 $, the functions $ t _ tf $ and $ g _ \ lambda f $ are lipschitzian and | \ nabla t _ tf ( x ) | \ leq t _ t | \ nabla f | ( x ) and | \ nabla g _ \ lambda f ( x ) | \ leq \ frac { 1 } { \ lambda } g _ \ lambda | \ nabla f | ( x ). an analogous result is proved in the parabolic case. | arxiv:math/0507079 |
type - i superluminous supernovae ( slsne ) are an exotic class of core - collapse sn ( ccsn ) that can be up to 100 times brighter and more slowly - evolving than normal ccsne. slsne represent the end - stages of the most massive stripped stars, and are thought to be powered by the spin - down energy of a millisecond magnetar. studying them and measuring their physical parameters can help us to better understand stellar mass - loss, evolution, and explosions. moreover, thanks to their high luminosities, slsne can be seen up to greater distances, allowing us to explore how stellar physics evolves as a function of redshift. the high latitude time domain survey ( hltds ) will provide us with an exquisite dataset that will discover 100s of slsne. here, we focus on the question of which sets of filters and cadences will allow us to best characterize the physical parameters of these slsne. we simulate a set of slsne at redshifts ranging from z = 0. 1 to z = 5. 0, using six different sets of filters, and cadences ranging from 5 to 100 days. we then fit these simulated light curves to attempt to recover the input parameter values for their ejecta mass, ejecta velocity, magnetic field strength, and magnetar spin period. we find that four filters are sufficient to accurately characterize slsne at redshifts below $ z = 3 $, and that cadences faster than 20 days are required to obtain measurements with an uncertainty below 10 \ %, although a cadence of 70 days is still acceptable under certain conditions. finally, we find that the nominal survey strategy will not be able to properly characterize the most distant slsne at $ z = 5 $. we find that the addition of 60 - day cadence observations for 4 years to the nominal hltds survey can greatly improve the prospect of characterizing these most extreme and distant sne, with only an 8 \ % increase to the time commitment of the survey. | arxiv:2306.17233 |
we construct games of chance from simpler games of chance. we show that it may happen that the simpler games of chance are fair or unfavourable to a player andyet the new combined game is favourable - - this is a counter - intuitive phenomenoknown as parrondo ' s paradox. we observe that all of the games in question are random walks in periodic environments ( rwpe ) when viewed on the proper time scale. consequently, we use rwpe techniques to derive conditions under which parrondo ' s paradox occurs. | arxiv:math/0206151 |
in this article, we prove that convex functions and log - convex functions obey certain general refinements that lead to several refinements and reverses of well known inequalities for matrices, including young ' s inequality, heinz inequality, the arithmetic - harmonic and the geometric - harmonic mean inequalities. | arxiv:1606.08099 |
electronic health records ( ehr ) serve as a valuable source of patient information, offering insights into medical histories, treatments, and outcomes. previous research has developed systems for detecting applicable icd codes that should be assigned while writing a given ehr document, mainly focusing on discharge summaries written at the end of a hospital stay. in this work, we investigate the potential of predicting these codes for the whole patient stay at different time points during their stay, even before they are officially assigned by clinicians. the development of methods to predict diagnoses and treatments earlier in advance could open opportunities for predictive medicine, such as identifying disease risks sooner, suggesting treatments, and optimizing resource allocation. our experiments show that predictions regarding final icd codes can be made already two days after admission and we propose a custom model that improves performance on this early prediction task. | arxiv:2405.11622 |
a hopf galois structure on a finite field extension $ l / k $ is a pair $ ( \ mathcal { h }, \ mu ) $, where $ \ mathcal { h } $ is a finite cocommutative $ k $ - hopf algebra and $ \ mu $ a hopf action. in this paper, we present several results on hopf galois structures on odd prime power degree separable field extensions. we prove that if a separable field extension of odd prime power degree has a hopf galois structure of cyclic type, then it has no structure of noncyclic type. we determine the number of hopf galois structures of cyclic type on a separable field extension of degree $ p ^ n $, $ p $ an odd prime, such that the galois group of its normal closure is a semidirect product $ c _ { p ^ n } \ rtimes c _ d $ of the cyclic group of order $ p ^ n $ and a cyclic group of order $ d $, with $ d $ prime to $ p $. we characterize the transitive groups of degree $ p ^ 3 $ which are galois groups of the normal closure of a separable field extension having some cyclic hopf galois structure and determine the number of those. we prove that if a separable field extension of degree $ p ^ 3 $ has a nonabelian hopf galois structure then it has an abelian structure whose type has the same exponent as the nonabelian type. we obtain that, for $ p > 3 $, the two abelian noncyclic hopf galois structures do not occur on the same separable extension of degree $ p ^ 3 $. we present a table which gives the number of hopf galois structures of each possible type on a separable extension of degree $ 27 $ to illustrate that for $ p = 3 $, all four noncyclic hopf galois structures may occur on the same extension. finally, putting together all previous results, we list all possible sets of hopf galois structure types on a separable extension of degree $ p ^ 3 $, for $ p > 3 $ a prime. | arxiv:1807.11409 |
we study the optical generation and control of coherent phonons in elemental bismuth ( bi ) and antimony ( sb ) using a classical equation of motion informed by first - principles calculations of the potential energy surface and the frequency - dependent macroscopic dielectric function along the zone - centered optical phonons coordinates. using this approach, we demonstrate that phonons with the largest optomechanical couplings, also have the strongest degree of anharmonicity among the zone - centered modes, a result of the broken symmetry structural ground state of bi and sb. we show how this anharmonicity, explaining the light - induced phonon softening observed in experiments, prevents the application of standard phonon - amplification and annihilation protocols. we introduce a simple linearization protocol that extends the use of such protocols to the case of anharmonic phonons in broken symmetry materials, and demonstrate its efficiency at high displacement amplitudes. our formalism and results provide a path for improving optical control in non - linear phononics. | arxiv:2307.11854 |
scene graphs capture complex relationships among objects, serving as strong priors for content generation and manipulation. yet, reasonably manipulating scene graphs - - whether by adding nodes or modifying edges - - remains a challenging and untouched task. tasks such as adding a node to the graph or reasoning about a node ' s relationships with all others are computationally intractable, as even a single edge modification can trigger conflicts due to the intricate interdependencies within the graph. to address these challenges, we introduce sg - tailor, an autoregressive model that predicts the conflict - free relationship between any two nodes. sg - tailor not only infers inter - object relationships, including generating commonsense edges for newly added nodes but also resolves conflicts arising from edge modifications to produce coherent, manipulated graphs for downstream tasks. for node addition, the model queries the target node and other nodes from the graph to predict the appropriate relationships. for edge modification, sg - tailor employs a cut - and - stitch strategy to solve the conflicts and globally adjust the graph. extensive experiments demonstrate that sg - tailor outperforms competing methods by a large margin and can be seamlessly integrated as a plug - in module for scene generation and robotic manipulation tasks. | arxiv:2503.18988 |
processing - in - memory ( pim ), as a novel computing paradigm, provides significant performance benefits from the aspect of effective data movement reduction. sram - based pim has been demonstrated as one of the most promising candidates due to its endurance and compatibility. however, the integration density of sram - based pim is much lower than other non - volatile memory - based ones, due to its inherent 6t structure for storing a single bit. within comparable area constraints, sram - based pim exhibits notably lower capacity. thus, aiming to unleash its capacity potential, we propose ddc - pim, an efficient algorithm / architecture co - design methodology that effectively doubles the equivalent data capacity. at the algorithmic level, we propose a filter - wise complementary correlation ( fcc ) algorithm to obtain a bitwise complementary pair. at the architecture level, we exploit the intrinsic cross - coupled structure of 6t sram to store the bitwise complementary pair in their complementary states ( $ q / \ overline { q } $ ), thereby maximizing the data capacity of each sram cell. the dual - broadcast input structure and reconfigurable unit support both depthwise and pointwise convolution, adhering to the requirements of various neural networks. evaluation results show that ddc - pim yields about $ 2. 84 \ times $ speedup on mobilenetv2 and $ 2. 69 \ times $ on efficientnet - b0 with negligible accuracy loss compared with pim baseline implementation. compared with state - of - the - art sram - based pim macros, ddc - pim achieves up to $ 8. 41 \ times $ and $ 2. 75 \ times $ improvement in weight density and area efficiency, respectively. | arxiv:2310.20424 |
in this article, we explicitly construct a canonical basis for the space of certain weakly holomorphic drinfeld modular forms for $ \ gamma _ 0 ( t ) $ ( resp., for $ \ gamma _ 0 ^ + ( t ) $ ) and compute the generating function satisfied by the basis elements. we also give an explicit expression for the action of the $ \ theta $ - operator, which depends on the divisor of meromorphic drinfeld modular forms. | arxiv:2303.14383 |
identifying design problems is a crucial step for creating plausible solutions, but it is challenging for design novices due to their limited knowledge and experience. questioning is a promising skill that enables students to independently identify design problems without being passive or relying on instructors. this study explores role - playing interactions with large language model ( llm ) - powered conversational agents ( cas ) to foster the questioning skills of novice design students. we proposed an llm - powered ca prototype and conducted a preliminary study with 16 novice design students engaged in a real - world design class to observe the interactions between students and the llm - powered cas. our findings indicate that while the cas stimulated questioning and reduced pressure to ask questions, it also inadvertently led to over - reliance on llm responses. we proposed design considerations and future works for llm - powered ca to foster questioning skills. | arxiv:2409.07178 |
in this paper, we propose a graph neural network architecture to solve the ac power flow problem under realistic constraints. to ensure a safe and resilient operation of distribution grids, ac power flow calculations are the means of choice to determine grid operating limits or analyze grid asset utilization in planning procedures. in our approach, we demonstrate the development of a framework that uses graph neural networks to learn the physical constraints of the power flow. we present our model architecture on which we perform unsupervised training to learn a general solution of the ac power flow formulation independent of the specific topologies and supply tasks used for training. finally, we demonstrate, validate and discuss our results on medium voltage benchmark grids. in our approach, we focus on the physical and topological properties of distribution grids to provide scalable solutions for real grid topologies. therefore, we take a data - driven approach, using large and diverse data sets consisting of realistic grid topologies, for the unsupervised training of the ac power flow graph neural network architecture and compare the results to a prior neural architecture and the newton - raphson method. our approach shows a high increase in computation time and good accuracy compared to state - of - the - art solvers. it also out - performs that neural solver for power flow in terms of accuracy. | arxiv:2204.07000 |
intersecting and cross - intersecting families usually appear in extremal combinatorics in the vein of the erd { \ h o } s - - ko - - rado theorem. on the other hand, p. ~ erd { \ h o } s and l. ~ lov { \ ' a } sz in the noted paper ~ \ cite { el } posed problems on coloring intersecting families as a restriction of classical hypergraph coloring problems to a special class of hypergraphs. this note deals with the mentioned coloring problems stated for cross - intersecting families. | arxiv:1707.04539 |
time - varying parameter ( tvp ) models often assume that the tvps evolve according to a random walk. this assumption, however, might be questionable since it implies that coefficients change smoothly and in an unbounded manner. in this paper, we relax this assumption by proposing a flexible law of motion for the tvps in large - scale vector autoregressions ( vars ). instead of imposing a restrictive random walk evolution of the latent states, we carefully design hierarchical mixture priors on the coefficients in the state equation. these priors effectively allow for discriminating between periods where coefficients evolve according to a random walk and times where the tvps are better characterized by a stationary stochastic process. moreover, this approach is capable of introducing dynamic sparsity by pushing small parameter changes towards zero if necessary. the merits of the model are illustrated by means of two applications. using synthetic data we show that our approach yields precise parameter estimates. when applied to us data, the model reveals interesting patterns of low - frequency dynamics in coefficients and forecasts well relative to a wide range of competing models. | arxiv:2006.10088 |
chronic rhinosinusitis ( crs ) is a common and persistent sinus imflammation that affects 5 - 12 \ % of the general population. it significantly impacts quality of life and is often difficult to assess due to its subjective nature in clinical evaluation. we introduce paraside, an automatic tool for segmenting air and soft tissue volumes of the structures of the sinus maxillaris, frontalis, sphenodalis and ethmoidalis in t1 mri. by utilizing that segmentation, we can quantify feature relations that have been observed only manually and subjectively before. we performed an exemplary study and showed both volume and intensity relations between structures and radiology reports. while the soft tissue segmentation is good, the automated annotations of the air volumes are excellent. the average intensity over air structures are consistently below those of the soft tissues, close to perfect separability. healthy subjects exhibit lower soft tissue volumes and lower intensities. our developed system is the first automated whole nasal segmentation of 16 structures, and capable of calculating medical relevant features such as the lund - mackay score. | arxiv:2501.14514 |
bayesian model averaging ( bma ) is an application of bayesian inference to the problems of model selection, combined estimation and prediction that produces a straightforward model choice criteria and less risky predictions. however, the application of bma is not always straightforward, leading to diverse assumptions and situational choices on its different aspects. despite the widespread application of bma in the literature, there were not many accounts of these differences and trends besides a few landmark revisions in the late 1990s and early 2000s, therefore not taking into account any advancements made in the last 15 years. in this work, we present an account of these developments through a careful content analysis of 587 articles in bma published between 1996 and 2014. we also develop a conceptual classification scheme to better describe this vast literature, understand its trends and future directions and provide guidance for the researcher interested in both the application and development of the methodology. the results of the classification scheme and content review are then used to discuss the present and future of the bma literature. | arxiv:1509.08864 |
ferromagnetic \ nmg has unique magnetoelastic properties. these are investigated by detailed computational studies of the phonon dispersion curves for the non - modulated cubic \ ltw and tetragonal structures. for the \ ltw \ structure, a complete softening of the transverse acoustic mode has been found around the wave vector $ \ mathbf { q } = [ 1 / 3, 1 / 3, 0 ] ( 2 \ pi / a ) $. the softening of this \ ta { 2 } phonon mode leads to the premartensitic modulated super - structure observed experimentally. further phonon anomalies, related to other structural transformations in \ nmg, have also been found and examined. these anomalies appear to be due to the coupling of particular acoustic phonon modes and optical modes derived from ni. | arxiv:cond-mat/0304315 |
the present work continues investigation of the capacities of measurement ( quantum - classical ) channels in the most general setting, initiated in ~ \ cite { hct }. the proof of coding theorems is given for the classical capacity and entanglement - assisted classical capacity of the measurement channel with arbitrary output alphabet, without assuming that the channel is given by a bounded operator - valued density. | arxiv:1408.3255 |
neutrino - nucleus elastic scattering ( $ \ nu { \ rm a } _ { el } $ ) provides a unique laboratory to study the quantum - mechanical ( qm ) coherency effects in electroweak interactions. the deviations of the cross - sections from those of completely coherent systems can be quantitatively characterized through a coherency parameter $ \ alpha ( q ^ 2 ) $. the relations between $ \ alpha $ and the underlying nuclear physics in terms of nuclear form factors are derived. the dependence of cross - section on $ \ alpha ( q ^ 2 ) $ for the various neutrino sources is presented. the $ \ alpha ( q ^ 2 ) $ - values are evaluated from the measured data of the coherent csi and ar experiments. complete coherency and decoherency conditions are excluded by the csi data with $ p { = } 0. 004 $ at $ q ^ 2 { = } 3. 1 { \ times } 10 ^ { 3 } ~ { \ rm mev ^ 2 } $ and with $ p { = } 0. 016 $ at $ q ^ 2 { = } 2. 3 { \ times } 10 ^ { 3 } ~ { \ rm mev ^ 2 } $, respectively, verifying that both qm superpositions and nuclear many - body effects contribute to $ \ nu { \ rm a } _ { el } $ interactions. | arxiv:2010.06810 |
since 1996, a hybrid experiment consisting of an emulsion chamber and a burst detector array and the tibet - ii air shower array has been operated at yangbajing ( 4300 m above sea level ) in tibet. this experiment can detect air - shower cores, called burst events, accompanied by air showers in excess of about 100 tev. using the burst event data observed by this experiment, we discuss the primary cosmic ray composition around the knee in comparison with the monte carlo simulations. in this paper, we show that all the features of burst events are wholly compatible with the heavy enriched composition in the knee energy region. | arxiv:astro-ph/0008043 |
trapped - ion quantum sensors have become highly sensitive tools for the search of physics beyond the standard model. recently, stringent tests of local lorentz - invariance ( lli ) have been conducted with precision spectroscopy in trapped ions. we here elaborate on robust and scalable radio - frequency composite - pulse spectroscopy at second long coherence times in the magnetic sublevels of the long - lived $ ^ { 2 } f _ { 7 / 2 } $ state of a trapped $ ^ { 172 } $ yb $ ^ { + } $ ion. we compare two ramsey - type composite rf pulse sequences, a generalized spin - echo ( gse ) sequence and a sequence based on universal rotations with 10 rephasing pulses ( ur10 ) that decouple the energy levels from magnetic field noise, enabling robust and accurate spectroscopy. both sequences are characterized theoretically and experimentally in the spin - $ 1 / 2 $ $ \ $ $ ^ { 2 } s _ { 1 / 2 } $ electronic ground state of $ ^ { 172 } $ yb $ ^ { + } $ and results show that the ur10 sequence is 38 ( 13 ) times more robust against pulse duration ( frequency detuning ) errors than the gse sequence. we extend our simulations to the eight - level manifold of the $ ^ 2f _ { 7 / 2 } $ state, which is highly sensitive to a possible violation of lli, and show that the ur10 sequence can be used for high - fidelity ramsey spectroscopy in noisy environments. the ur10 sequence is implemented experimentally in the $ ^ 2f _ { 7 / 2 } $ manifold and a coherent signal of up to $ 2. 5 \, $ s is reached. we have implemented the sequence and used it to perform the most stringent test of lli in the electron - photon sector to date. due to the robustness of the ur10 sequence, it can be applied on larger ion crystals to improve tests of lorentz symmetry further. we demonstrate that the sequence can also be used to extract the quadrupole moment of the meta - stable $ ^ { 2 } f _ { 7 / 2 } $ state, obtaining a value of $ \ theta \, = \, - 0. 0298 ( 38 ) \, ea ^ { 2 } _ { 0 } $ which is in agreement with the value deduced from clock measurements. | arxiv:2306.01486 |
we comment on the paper published by w. b. gao, q. q. liu, l. x. yang, y. yu, f. y. li, c. q. jin and s. uchida in phys. rev. b 80, 094523 ( 2009 ) and give alternate explanations for the enhanced superconductivity. the enhanced onset tc of 98k observed upon substituting ba for sr is attributed to optimal oxygen ordering rather than to the increase in volume. comparison with la2cuo ( 4 + x ) samples suggest that the effect of disorder is overestimated. | arxiv:1002.1725 |
when simulating trajectories by integrating time - continuous car - following models, standard integration schemes such as the forth - order runge - kutta method ( rk4 ) are rarely used while the simple euler ' s method is popular among researchers. we compare four explicit methods : euler ' s method, ballistic update, heun ' s method ( trapezoidal rule ), and the standard forth - order rk4. as performance metrics, we plot the global discretization error as a function of the numerical complexity. we tested the methods on several time - continuous car - following models in several multi - vehicle simulation scenarios with and without discontinuities such as stops or a discontinuous behavior of an external leader. we find that the theoretical advantage of rk4 ( consistency order ~ 4 ) only plays a role if both the acceleration function of the model and the external data of the simulation scenario are sufficiently often differentiable. otherwise, we obtain lower ( and often fractional ) consistency orders. although, to our knowledge, heun ' s method has never been used for integrating car - following models, it turns out to be the best scheme for many practical situations. the ballistic update always prevails euler ' s method although both are of first order. | arxiv:1403.4881 |
forgetting refers to the loss or deterioration of previously acquired knowledge. while existing surveys on forgetting have primarily focused on continual learning, forgetting is a prevalent phenomenon observed in various other research domains within deep learning. forgetting manifests in research fields such as generative models due to generator shifts, and federated learning due to heterogeneous data distributions across clients. addressing forgetting encompasses several challenges, including balancing the retention of old task knowledge with fast learning of new task, managing task interference with conflicting goals, and preventing privacy leakage, etc. moreover, most existing surveys on continual learning implicitly assume that forgetting is always harmful. in contrast, our survey argues that forgetting is a double - edged sword and can be beneficial and desirable in certain cases, such as privacy - preserving scenarios. by exploring forgetting in a broader context, we present a more nuanced understanding of this phenomenon and highlight its potential advantages. through this comprehensive survey, we aspire to uncover potential solutions by drawing upon ideas and approaches from various fields that have dealt with forgetting. by examining forgetting beyond its conventional boundaries, we hope to encourage the development of novel strategies for mitigating, harnessing, or even embracing forgetting in real applications. a comprehensive list of papers about forgetting in various research fields is available at \ url { https : / / github. com / ennengyang / awesome - forgetting - in - deep - learning }. | arxiv:2307.09218 |
using our catalogue of v $ _ { 26. 5 } $ isophotal magnitudes for 6756 galaxies in a region covering 60 ~ $ \ times $ ~ 25 ~ arcmin $ ^ 2 $ in the center of the coma cluster, plus 267 galaxies in a region of 9. 7 ~ $ \ times $ ~ 9. 4 ~ arcmin $ ^ 2 $ around ngc ~ 4839, we derive the luminosity function in the magnitude range 13. 5 $ \ leq v _ { 26. 5 } < $ 21. 0 ( corresponding to the absolute magnitude range $ - 22. 24 < m _ { v26. 5 } \ leq - 14. 74 $ ). the luminosity function for this region is well fitted by the combination of a gaussian in its bright part and of a steep schechter function ( of index $ \ alpha = - 1. 8 $ ) in its faint part. luminosity functions derived for individual regions surrounding the brightest galaxies show less steep slopes, strongly suggesting the existence of environmental effects. the implications of such effects and galaxy formation scenarios are discussed. | arxiv:astro-ph/9605194 |
a recent work of larsen [ lar23 ] gave a faster combinatorial alternative to bansal ' s sdp algorithm for finding a coloring $ x \ in \ { - 1, 1 \ } ^ n $ that approximately minimizes the discrepancy $ \ mathrm { disc } ( a, x ) : = \ | a x \ | _ { \ infty } $ of a general real - valued $ m \ times n $ matrix $ a $. larsen ' s algorithm runs in $ \ widetilde { o } ( mn ^ 2 ) $ time compared to bansal ' s $ \ widetilde { o } ( mn ^ { 4. 5 } ) $ - time algorithm, at the price of a slightly weaker logarithmic approximation ratio in terms of the hereditary discrepancy of $ a $ [ ban10 ]. in this work we present a combinatorial $ \ widetilde { o } ( \ mathrm { nnz } ( a ) + n ^ 3 ) $ time algorithm with the same approximation guarantee as larsen, which is optimal for tall matrices $ m = \ mathrm { poly } ( n ) $. using a more intricate analysis and fast matrix - multiplication, we achieve $ \ widetilde { o } ( \ mathrm { nnz } ( a ) + n ^ { 2. 53 } ) $ time, which breaks cubic runtime for square matrices, and bypasses the barrier of linear - programming approaches [ es14 ] for which input - sparsity time is currently out of reach. our algorithm relies on two main ideas : ( i ) a new sketching technique for finding a projection matrix with short $ \ ell _ 2 $ - basis using implicit leverage - score sampling ; ( ii ) a data structure for faster implementation of the iterative edge - walk partial - coloring algorithm of lovett - meka, using an alternative analysis that enables ` ` lazy " batch - updates with low - rank corrections. our result nearly closes the computational gap between real - valued and binary matrices ( set - systems ), for which input - sparsity time coloring was very recently obtained [ jss23 ]. | arxiv:2210.12468 |
in a nonlocal game, two noncommunicating players cooperate to convince a referee that they possess a strategy that does not violate the rules of the game. quantum strategies allow players to optimally win some games by performing joint measurements on a shared entangled state, but computing these strategies can be challenging. we present a variational quantum algorithm to compute quantum strategies for nonlocal games by encoding the rules of a nonlocal game into a hamiltonian. we show how this algorithm can generate a short - depth optimal quantum strategy for a graph coloring game with a quantum advantage. this quantum strategy is then evaluated on fourteen different quantum hardware platforms to demonstrate its utility as a benchmark. finally, we discuss potential sources of errors that can explain the observed decreased performance of the executed task and derive an expression for the number of samples required to accurately estimate the win rate in the presence of noise. | arxiv:2311.01363 |
this paper examines the potential role of unit consistency as a system design principle. unit - consistent generalized matrix inverses and unit - invariant matrix decompositions are derived in support of this principle. applications of the methods described are illustrated with examples relating to nonlinear system identification and robustness to multiplicative noise for image database retrieval. | arxiv:1604.08476 |
we continue our earlier studies of quasi - periodic oscillations ( qpos ) in the power spectra of accreting, rapidly - rotating black holes that originate from the geometric " light echoes " of x - ray flares occurring within the black hole ergosphere. our present work extends our previous treatment to three - dimensional photon emission and orbits to allow for arbitrary latitudes in the positions of the distant observers and the x - ray sources in place of the mainly equatorial positions and photon orbits of the earlier consideration. following the trajectories of a large number of photons we calculate the response functions of a given geometry and use them to produce model light curves which we subsequently analyze to compute their power spectra and autocorrelation functions. in the case of an optically - thin environment, relevant to advection - dominated accretion flows, we consistently find qpos at frequencies of order of ~ khz for stellar - mass black hole candidates while order of ~ mhz for typical active galactic nuclei ( ~ 10 ^ 7 msun ) for a wide range of viewing angles ( 30 to 80deg ) from x - ray sources predominantly concentrated toward the equator within the ergosphere. as in our previous treatment, here too, the qpo signal is produced by the frame - dragging of the photons by the rapidly - rotating black hole, which results in photon " bunches " separated by constant time - lags, the result of multiple photon orbits around the hole. our model predicts for various source / observer configurations the robust presence of a new class of qpos, which is inevitably generic to curved spacetime structure in rotating black hole systems. | arxiv:0901.2858 |
we have investigated the mechanism of stabilizing the simple - cubic ( sc ) structure in polonium ( alpha - po ), based on the phonon dispersion calculations using the first - principles all - electron band method. we have demonstrated that the stable sc structure results from the suppression of the peierls instability due to the strong spin - orbit coupling ( soc ) in alpha - po. further, we have explored the possible superconductivity in alpha - po, and predicted that it becomes a superconductor with tc ~ 4 k. the transverse soft phonon mode at q ~ 2 / 3 r, which is greatly influenced by the soc, plays an important role both in the structural stability and the superconductivity in alpha - po. we have discussed effects of the soc and the volume variation on the phonon dispersions and superconducting properties of alpha - po. | arxiv:1112.4224 |
this paper presents an investigation of the notion of reaction time in some synchronous systems. a state - based description of such systems is given, and the reaction time of such systems under some classic composition primitives is studied. reaction time is shown to be non - compositional in general. possible solutions are proposed, and applications to verification are discussed. this framework is illustrated by some examples issued from studies on real - time embedded systems. | arxiv:1108.0467 |
we consider straggler - resilient learning. in many previous works, e. g., in the coded computing literature, straggling is modeled as random delays that are independent and identically distributed between workers. however, in many practical scenarios, a given worker may straggle over an extended period of time. we propose a latency model that captures this behavior and is substantiated by traces collected on microsoft azure, amazon web services ( aws ), and a small local cluster. building on this model, we propose dsag, a mixed synchronous - asynchronous iterative optimization method, based on the stochastic average gradient ( sag ) method, that combines timely and stale results. we also propose a dynamic load - balancing strategy to further reduce the impact of straggling workers. we evaluate dsag for principal component analysis, cast as a finite - sum optimization problem, of a large genomics dataset, and for logistic regression on a cluster composed of 100 workers on aws, and find that dsag is up to about 50 % faster than sag, and more than twice as fast as coded computing methods, for the particular scenario that we consider. | arxiv:2111.13877 |
let $ x $ be a connected smooth complex projective variety of dimension $ n \ geq 1 $. let $ d $ be a simple normal crossing divisor on $ x $. let $ g $ be a connected complex lie group, and $ e _ g $ a holomorphic principal $ g $ - bundle on $ x $. in this article, we give criterion for existence of a logarithmic connection on $ e _ g $ singular along $ d $. | arxiv:1912.00598 |
we propose an efficient framework for enabling secure multi - party numerical computations in a peer - to - peer network. this problem arises in a range of applications such as collaborative filtering, distributed computation of trust and reputation, monitoring and other tasks, where the computing nodes is expected to preserve the privacy of their inputs while performing a joint computation of a certain function. although there is a rich literature in the field of distributed systems security concerning secure multi - party computation, in practice it is hard to deploy those methods in very large scale peer - to - peer networks. in this work, we try to bridge the gap between theoretical algorithms in the security domain, and a practical peer - to - peer deployment. we consider two security models. the first is the semi - honest model where peers correctly follow the protocol, but try to reveal private information. we provide three possible schemes for secure multi - party numerical computation for this model and identify a single light - weight scheme which outperforms the others. using extensive simulation results over real internet topologies, we demonstrate that our scheme is scalable to very large networks, with up to millions of nodes. the second model we consider is the malicious peers model, where peers can behave arbitrarily, deliberately trying to affect the results of the computation as well as compromising the privacy of other peers. for this model we provide a fourth scheme to defend the execution of the computation against the malicious peers. the proposed scheme has a higher complexity relative to the semi - honest model. overall, we provide the peer - to - peer network designer a set of tools to choose from, based on the desired level of security. | arxiv:0901.2689 |
given multiple source domains, domain generalization aims at learning a universal model that performs well on any unseen but related target domain. in this work, we focus on the domain generalization scenario where domain shifts occur among class - conditional distributions of different domains. existing approaches are not sufficiently robust when the variation of conditional distributions given the same class is large. in this work, we extend the concept of distributional robust optimization to solve the class - conditional domain generalization problem. our approach optimizes the worst - case performance of a classifier over class - conditional distributions within a wasserstein ball centered around the barycenter of the source conditional distributions. we also propose an iterative algorithm for learning the optimal radius of the wasserstein balls automatically. experiments show that the proposed framework has better performance on unseen target domain than approaches without domain generalization. | arxiv:2109.03676 |
a puzzling discrepancy exists between the values of the proton charge radius obtained using different experimental techniques : elastic electron - proton scattering and spectroscopy of electronic and muonic hydrogen. the proton radius is defined through the slope of the electric form factor, $ g _ e ( q ^ 2 ) $, at zero four - momentum transfer, which is inaccessible in scattering experiments. we propose a novel method for extracting the proton radius from scattering data over a broad $ q ^ 2 $ range rather than attempting to directly determine the slope of $ g _ e $ at $ q ^ 2 = 0 $. this method relates the radius of the proton to its transverse charge density, which is the two - dimensional fourier transform of the dirac form factor, $ f _ 1 ( q ^ 2 ) $. we apply our method to reanalyze the extensive data obtained by the a1 collaboration [ j. c. bernauer et al., phys. rev. lett. 105, 242001 ( 2010 ) ] and extract a radius value, $ r _ e = 0. 889 ( 5 ) _ { \ text { stat } } ( 5 ) _ { \ text { syst } } ( 4 ) _ { \ text { model } } ~ \ text { fm } $, that is consistent with the original result. we also provide new parametrizations for the dirac and pauli form factors and the transverse charge and magnetization densities of the proton. our reanalysis shows that the proton radius discrepancy cannot be explained by issues with fitting and extrapolating the a1 data to $ q ^ 2 = 0 $. | arxiv:2102.13022 |
how to build an effective large - scale traffic state prediction system is a challenging but highly valuable problem. this study focuses on the construction of an effective solution designed for spatio - temporal data to predict large - scale traffic state. considering the large data size in traffic4cast challenge and our limited computational resources, we emphasize model design to achieve a relatively high prediction performance within acceptable running time. we adopt a structure similar to u - net and use a mask instead of spatial attention to address the data sparsity. then, combined with the experience of time series prediction problem, we design a number of features, which are input into the model as different channels. region cropping is used to decrease the difference between the size of the receptive field and the study area, and the models can be specially optimized for each sub - region. the fusion of interdisciplinary knowledge and experience is an emerging demand in classical traffic research. several interdisciplinary studies we have been studying are also discussed in the complementary challenges. the source codes are available in https : / / github. com / wufanyou / traffic4cast - tlab. | arxiv:1911.05699 |
we investigate the possibility that primordial black holes ( pbhs ) can be formed from large curvature perturbations generated during the waterfall phase transition in a supersymmetric scenario where sneutrino is the inflaton in a hybrid inflationary framework. we obtain a spectral index ( $ n _ s \ simeq 0. 966 $ ), and a tensor - to - scalar ratio ( $ r \ simeq 0. 0056 - 10 ^ { - 11 } $ ), consistent with the current planck data satisfying pbh as dark matter ( dm ) and detectable gravitational wave ( gw ) signal. our findings show that the mass of pbh and the peak in the gw spectrum is correlated with the right - handed ( s ) neutrino mass. we identify parameter space where pbhs can be the entire dm candidate of the universe ( with mass $ 10 ^ { - 13 } \, m _ \ odot $ ) or a fraction of it. this can be tested in future observatories, for example, with amplitude $ \ omega _ { \ rm gw } h ^ 2 $ $ \ sim 10 ^ { - 9 } $ and peak frequency $ f \ sim 0. 1 $ hz in lisa and $ \ omega _ { \ rm gw } h ^ 2 \ sim 10 ^ { - 11 } $ and peak frequency of $ \ sim 10 $ hz in et via second - order gw signals. we study two models of sneutrino inflation : model $ - 1 $ involves canonical sneutrino kinetic term which predicts the sub - planckian mass parameter $ m $, while the coupling between a gauge singlet and the waterfall field, $ \ beta $, needs to be quite large whereas, for the model $ - 2 $ involving $ \ alpha - $ attractor canonical sneutrino kinetic term, $ \ beta $ can take a natural value. estimating explicitly, we show that both models have mild fine - tuning. we also derive an analytical expression for the power spectrum in terms of the microphysics parameters of the model like ( s ) neutrino mass, etc. that fits well with the numerical results. the typical reheat temperature for both the models is around $ 10 ^ { 7 } - 10 ^ { 8 } $ ~ gev suitable for non - thermal leptogenesis. | arxiv:2407.15082 |
random forests are a scheme proposed by leo breiman in the 2000 ' s for building a predictor ensemble with a set of decision trees that grow in randomly selected subspaces of data. despite growing interest and practical use, there has been little exploration of the statistical properties of random forests, and little is known about the mathematical forces driving the algorithm. in this paper, we offer an in - depth analysis of a random forests model suggested by breiman in \ cite { bre04 }, which is very close to the original algorithm. we show in particular that the procedure is consistent and adapts to sparsity, in the sense that its rate of convergence depends only on the number of strong features and not on how many noise variables are present. | arxiv:1005.0208 |
accurate parameters of the host stars of exoplanets are important for the interpretation of the new planet systems that continue to emerge. the corot satellite recently discovered a transiting rocky planet with a density similar to the inner planets in our solar system, a so - called super earth. this planet is orbiting a relatively faint g9v star called corot - 7, and we wish to refine its physical properties, which are important for the interpretation of the properties of the planet system. we used spectra from harps @ eso - 3. 6m and uves @ vlt - 8. 2m. from the analysis of fe - 1 and fe - 2 lines we determine teff, log g and microturbulence. we use the balmer lines to constrain teff and pressure sensitive mg - 1b and ca lines to constrain log g. from the analysis we find teff = 5250 + - 60k, log g = 4. 47 + - 0. 05, [ m / h ] = + 0. 12 + - 0. 06, and vsini = 1. 1 km / s. we compared the l / m ratio with isochrones to constrain the evolutionary status. using the age estimate of 1. 2 - 2. 3 gyr based on stellar activity, we determine the mass and radius 0. 91 + - 0. 03 msun and 0. 82 + - 0. 04 rsun. with these updated constraints we fitted the corot transit light curve for corot - 7b. we revise the planet radius to be slightly smaller, r = 1. 58 + - 0. 10 rearth, and the density becomes higher, rho = 7. 2 + - 1. 8 g / cm3. the host star corot - 7 is a slowly rotating, metal rich, unevolved type g9v star. the star is relatively faint ( v = 11. 7 ) and its fundamental parameters can only be determined through indirect methods. our methods rely on detailed spectral analyses that depend on the adopted model atmospheres. from the analysis of spectra of stars with well - known parameters with similar parameters to corot - 7 ( the sun and alpha cen b ) we demonstrate that our methods are robust within the claimed uncertainties. therefore our methods can be reliably used in subsequent analyses of similar exoplanet host stars. | arxiv:1005.3208 |
in liouville quantum gravity ( or $ 2d $ - gaussian multiplicative chaos ) one seeks to define a measure $ \ mu ^ h = e ^ { \ gamma h ( z ) } dz $ where $ h $ is an instance of the gaussian free field on a planar domain $ d $. since $ h $ is a distribution, not a function, one needs a regularization procedure to make this precise : for example, one may let $ h _ \ epsilon ( z ) $ be the average value of $ h $ on the circle of radius $ \ epsilon $ centered at $ z $ ( or an analogous average defined using a bump function supported inside that circle ) and then write $ \ mu ^ h = \ lim _ { \ epsilon \ to 0 } \ epsilon ^ { \ frac { \ gamma ^ 2 } { 2 } } e ^ { \ gamma h _ \ epsilon ( z ) } dz $. if $ \ phi : \ tilde d \ to d $ is a conformal map, one can write $ \ tilde h = h \ circ \ phi + q \ log | \ phi ' | $, where $ q = 2 / \ gamma + \ gamma / 2 $. the measure $ \ mu ^ { \ tilde h } $ on $ \ tilde d $ is then a. s. \ equivalent to the pullback via $ \ phi ^ { - 1 } $ of the measure $ \ mu ^ h $ on $ d $. interestingly, although this a. s. \ holds for each \ textit { given } $ \ phi $, nobody has ever proved that it a. s. \ holds \ textit { simultaneously } for all possible $ \ phi $. we will prove that this is indeed the case. this is conceptually important because one frequently defines a \ textit { quantum surface } to be an equivalence class of pairs $ ( d, h ) $ ( where pairs such as the $ ( d, h ) $ and $ ( \ tilde d, \ tilde h ) $ above are considered equivalent ) and it is useful to know that the set of pairs $ ( d, \ mu ^ { h } ) $ obtained from the set of pairs $ ( d, h ) $ in an equivalence class is itself an equivalence class with respect to the usual measure pullback relation. | arxiv:1605.06171 |
we consider a point particle coupled to 2 + 1 gravity, with de sitter gauge group so ( 3, 1 ). we observe that there are two contraction limits of the gauge group : one resulting in the poincare group, and the second with the gauge group having the form an ( 2 ) \ ltimes \ an ( 2 ) ^ *. the former case was thoroughly discussed in the literature, while the latter leads to the deformed particle action with de sitter momentum space, like in the case of kappa - poincare particle. however, the construction forces the mass shell constraint to have the form p _ 0 ^ 2 = m ^ 2, so that the effective particle action describes the deformed carroll particle. | arxiv:1408.0154 |
this paper proposes a multiplicative component intraday volatility model. the intraday conditional volatility is expressed as the product of intraday periodic component, intraday stochastic volatility component and daily conditional volatility component. i extend the multiplicative component intraday volatility model of engle ( 2012 ) and andersen and bollerslev ( 1998 ) by incorporating the durations between consecutive transactions. the model can be applied to both regularly and irregularly spaced returns. i also provide a nonparametric estimation technique of the intraday volatility periodicity. the empirical results suggest the model can successfully capture the interdependency of intraday returns. | arxiv:2111.02376 |
this paper explores the relationship between mirror symmetry for p ^ 2, at the level of big quantum cohomology, and tropical geometry. the mirror of p ^ 2 is typically taken to be ( ( c ^ * ) ^ 2, w ), where w is a landau - ginzburg potential of the form x + y + 1 / xy. the complex moduli space of the mirror is the universal unfolding of w, and oscillatory integrals produce a frobenius manifold structure on this universal unfolding. we show that w can be deformed by counting maslov index two tropical disks, and the natural paramaters appearing in this deformation are then the flat coordinates on the moduli space. furthermore, the oscillatory integrals are shown to read off directly tropical curve counts from the potential. thus we show in fact that mirror symmetry for p ^ 2 is equivalent in a strong sense to tropical curve counting formulas, including tropical formulas for gravitational descendent invariants. | arxiv:0903.1378 |
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