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over the past decade, integrated quantum photonic technologies have shown great potential as a platform for studying quantum phenomena and realizing large - scale quantum information processing. recently, there have been proposals for utilizing waveguide lattices to implement quantum gates, providing a more compact and robust solution compared to discrete implementation with directional couplers and phase shifters. we report on the first demonstration of precise control of single photon states on an $ 11 \ times 11 $ continuously - coupled programmable waveguide array. through electro - optical control, the array is subdivided into decoupled subcircuits and the degree of on - chip quantum interference can be tuned with a maximum visibility of 0. 962 $ \ pm $ 0. 013. furthermore, we show simultaneous control of two subcircuits on a single device. our results demonstrate the potential of using this technology as a building block for quantum information processing applications.
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arxiv:2405.13654
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we use the immersed curves description of bordered floer homology to study $ d $ - invariants of double branched covers $ \ sigma _ 2 ( l ) $ of arborescent links $ l \ subset s ^ 3 $. we define a new invariant $ \ delta _ { sym } $ of bordered $ \ mathbb { z } _ 2 $ - homology solid tori from an involution of the associated immersed curves and relate it to both the $ d $ - invariants and the neumann - siebenmann $ \ bar \ mu $ - invariants of certain fillings. we deduce that if $ l $ is a 2 - component arborescent link and $ \ sigma _ 2 ( l ) $ is an l - space, then the spin $ d $ - invariants of $ \ sigma _ 2 ( l ) $ are determined by the signatures of $ l $. by a separate argument, we show that the same relationship holds when $ l $ is a 2 - component link that admits a certain symmetry.
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arxiv:2408.02857
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unique transformation properties under the hyperspherical inversion of a partial differential equation describing a stationary scalar wave in an $ n $ - dimensional ( $ n \ geqslant2 $ ) maxwell fish - eye medium are exploited to construct a closed form of the green ' s function for that equation. for those wave numbers for which the green ' s function fails to exist, the generalized green ' s function is derived. prospective physical applications are mentioned.
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arxiv:1107.1466
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a microscopic model for a translational brownian motor, dubbed as brownian translator, is introduced. it is inspired by the brownian gyrator of filliger and reimann ( filliger and reimann 2007 ). the brownian translator consists of a spatially asymmetric object moving freely along a line due to perpetual collisions with a surrounding ideal gas. when this gas has an anisotropic temperature, both spatial and temporal symmetries are broken and the object acquires a nonzero drift. onsager reciprocity implies the opposite phenomenon, that is dragging a spatially asymmetric object in an ( initially at ) equilibrium gas induces an energy flow that results in anisotropic gas temperatures. expressions for the dynamical and energetic properties are derived as a series expansion in the mass ratio ( of gas particle vs. object ). these results are in excellent agreement with molecular dynamics simulations.
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arxiv:2312.13158
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inspired by an example of gueritaud - kassel [ geom. topol. 2017 ], we construct a family of infinitely generated discontinuous groups $ \ gamma $ for the 3 - dimensional anti - de sitter space $ \ mathrm { ads } ^ { 3 } $. these groups are not necessarily sharp ( a kind of " strong " properly discontinuous condition introduced by kassel and kobayashi [ adv. math. 2016 ] ), and we give its criterion. moreover, we find upper and lower bounds of the counting $ n _ { \ gamma } ( r ) $ of a $ \ gamma $ - orbit contained in a pseudo - ball $ b ( r ) $ as the radius $ r $ tends to infinity. we then find a non - sharp discontinuous group $ \ gamma $ for which there exist infinitely many $ l ^ 2 $ - eigenvalues of the laplacian on the noncompact anti - de sitter manifold $ \ gamma \ backslash \ mathrm { ads } ^ { 3 } $, by applying the method established by kassel - kobayashi. we also prove that for any increasing function $ f $, there exists a discontinuous group $ \ gamma $ for $ \ mathrm { ads } ^ { 3 } $ such that the counting $ n _ { \ gamma } ( r ) $ of a $ \ gamma $ - orbit is larger than $ f ( r ) $ for sufficiently large $ r $.
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arxiv:1907.09303
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the formation of pulses of surface electromagnetic waves in a metal / dielectric interface is considered in the process of cooperative decay of excitons of quantum dots distributed near a metal surface in a dielectric layer. it is shown that the efficiency of exciton energy transfer to excited plasmons can be increased by selecting the dielectric material with specified values of the complex permittivity. it is found that in the mean field approximation the semiclassical model of formation of plasmon pulses in the system under study is reduced to the pendulum equation with the additional term of nonlinear losses.
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arxiv:1702.06721
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using a single particle density distribution for a system of self - gravitating particles which ultimately forms a black hole, we from a condensed matter point of view derive the schwarzschild radius and by including the quantum mechanical exchange energy we find a small correction to the schwarzschild radius, which we designate as the skin of the black hole.
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arxiv:physics/0703173
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we use the new nilpotent formulation of open - closed string field theory to explore the limit where the number $ n $ of identical d - branes of the starting background is large. by reformulating the theory in terms of the ' t hooft coupling $ \ lambda = \ kappa n $, where $ \ kappa $ is the string coupling constant, we explicitly see that at large $ n $ only genus zero vertices with arbitrary number of boundaries survive. after discussing the homotopy structure of the obtained large $ n $ open - closed theory we discuss the possibility of integrating out the open string sector with a quantum but planar homotopy transfer. as a result we end up with a classical closed string field theory described by a weak $ l _ \ infty $ - algebra, containing a tree - level tadpole which, to first order in $ \ lambda $, is given by the initial boundary state. we discuss the possibility of removing the tadpole with a closed string vacuum shift solution, to end up with a new classical closed string background, where the initial d - branes have been turned into pure closed - string backreaction.
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arxiv:2305.02844
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protocols for non - adiabatic quantum control often require the use of classical time varying fields. assessing the thermodynamic cost of such protocols, however, is far from trivial. in this letter we study the irreversible entropy produced by the classical apparatus generating the control fields, thus providing a direct link between the cost of a control protocol and dissipation. we focus, in particular, on the case of time - dependent magnetic fields and shortcuts to adiabaticity. our results are showcased with two experimentally realisable case studies : the landau - zener model of a spin - 1 / 2 particle in a magnetic field and an ion confined in a penning trap.
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arxiv:2204.03012
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the recently released gpt - 4 code interpreter has demonstrated remarkable proficiency in solving challenging math problems, primarily attributed to its ability to seamlessly reason with natural language, generate code, execute code, and continue reasoning based on the execution output. in this paper, we present a method to fine - tune open - source language models, enabling them to use code for modeling and deriving math equations and, consequently, enhancing their mathematical reasoning abilities. we propose a method of generating novel and high - quality datasets with math problems and their code - based solutions, referred to as mathcodeinstruct. each solution interleaves natural language, code, and execution results. we also introduce a customized supervised fine - tuning and inference approach. this approach yields the mathcoder models, a family of models capable of generating code - based solutions for solving challenging math problems. impressively, the mathcoder models achieve state - of - the - art scores among open - source llms on the math ( 45. 2 % ) and gsm8k ( 83. 9 % ) datasets, substantially outperforming other open - source alternatives. notably, the mathcoder model not only surpasses chatgpt - 3. 5 and palm - 2 on gsm8k and math but also outperforms gpt - 4 on the competition - level math dataset. the dataset and models will be released at https : / / github. com / mathllm / mathcoder.
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arxiv:2310.03731
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using the latest data pertaining to \ bar u - \ bar d asymmetry and the spin polarization functions, detailed implications of the possible values of the coupling strength of the singlet goldstone boson \ eta ' have been investigated in the \ chicqm with configuration mixing. using \ delta u, \ delta _ 3, \ bar u - \ bar d and \ bar u / \ bar d, the possible ranges of the coupling parameters a, \ alpha ^ 2, \ beta ^ 2 and \ zeta ^ 2, representing respectively the probabilities of fluctuations to pions, k, \ eta and \ eta ^ { ' }, are shown to be 0. 10 \ lesssim a \ lesssim 0. 14, 0. 2 \ lesssim \ alpha \ lesssim 0. 5, 0. 2 \ lesssim \ beta \ lesssim 0. 7 and 0. 10 lesssim | \ zeta | \ lesssim 0. 70. to constrain the coupling strength of \ eta ', detailed fits have been obtained for spin polarization functions, quark distribution functions and baryon octet magnetic moments corresponding to the following sets of parameters : a = 0. 1, \ alpha = 0. 4, \ beta = 0. 7, | \ zeta | = 0. 65 ( case i ) ; a = 0. 1, \ alpha = 0. 4, \ beta = 0. 6, | \ zeta | = 0. 70 ( case ii ) ; a = 0. 14, \ alpha = 0. 4, \ beta = 0. 2, \ zeta = 0 ( case iii ) and a = 0. 13, \ alpha = \ beta = 0. 45, | \ zeta | = 0. 10 ( case iv ). case i represents the calculations where a is fixed to be 0. 1, in accordance with earlier calculations, whereas other parameters are treated free and the case iv represents our best fit. the fits clearly establish that a small non - zero value of the coupling of \ eta ' is preferred over the higher values of \ eta ' as well as when \ zeta = 0, the latter implying the absence of \ eta ' from the dynamics of \ chicqm. our best fit achieves an overall excellent fit to the data, in particular the fit for \ delta u, \ delta d, \ delta _ 8 as well as the magnetic moments \ mu _ { n }, \ mu _ { \ sigma ^
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arxiv:hep-ph/0505224
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a key challenge for autonomous vehicles is to navigate in unseen dynamic environments. separating moving objects from static ones is essential for navigation, pose estimation, and understanding how other traffic participants are likely to move in the near future. in this work, we tackle the problem of distinguishing 3d lidar points that belong to currently moving objects, like walking pedestrians or driving cars, from points that are obtained from non - moving objects, like walls but also parked cars. our approach takes a sequence of observed lidar scans and turns them into a voxelized sparse 4d point cloud. we apply computationally efficient sparse 4d convolutions to jointly extract spatial and temporal features and predict moving object confidence scores for all points in the sequence. we develop a receding horizon strategy that allows us to predict moving objects online and to refine predictions on the go based on new observations. we use a binary bayes filter to recursively integrate new predictions of a scan resulting in more robust estimation. we evaluate our approach on the semantickitti moving object segmentation challenge and show more accurate predictions than existing methods. since our approach only operates on the geometric information of point clouds over time, it generalizes well to new, unseen environments, which we evaluate on the apollo dataset.
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arxiv:2206.04129
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in this paper, for a given conservative solution, we introduce a set of auxiliary variables tailored to this particular solution, and prove that these variables satisfy a particular semilinear system having unique solutions. in turn, we get the uniqueness of the conservative solution in the original variables.
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arxiv:2310.15726
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large neural networks excel in many domains, but they are expensive to train and fine - tune. a popular approach to reduce their compute or memory requirements is to replace dense weight matrices with structured ones ( e. g., sparse, low - rank, fourier transform ). these methods have not seen widespread adoption ( 1 ) in end - to - end training due to unfavorable efficiency - - quality tradeoffs, and ( 2 ) in dense - to - sparse fine - tuning due to lack of tractable algorithms to approximate a given dense weight matrix. to address these issues, we propose a class of matrices ( monarch ) that is hardware - efficient ( they are parameterized as products of two block - diagonal matrices for better hardware utilization ) and expressive ( they can represent many commonly used transforms ). surprisingly, the problem of approximating a dense weight matrix with a monarch matrix, though nonconvex, has an analytical optimal solution. these properties of monarch matrices unlock new ways to train and fine - tune sparse and dense models. we empirically validate that monarch can achieve favorable accuracy - efficiency tradeoffs in several end - to - end sparse training applications : speeding up vit and gpt - 2 training on imagenet classification and wikitext - 103 language modeling by 2x with comparable model quality, and reducing the error on pde solving and mri reconstruction tasks by 40 %. in sparse - to - dense training, with a simple technique called " reverse sparsification, " monarch matrices serve as a useful intermediate representation to speed up gpt - 2 pretraining on openwebtext by 2x without quality drop. the same technique brings 23 % faster bert pretraining than even the very optimized implementation from nvidia that set the mlperf 1. 1 record. in dense - to - sparse fine - tuning, as a proof - of - concept, our monarch approximation algorithm speeds up bert fine - tuning on glue by 1. 7x with comparable accuracy.
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arxiv:2204.00595
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taking advantage of the known analytic expression of the eigenfunctions and eigenenergies of the morse hamiltonian, explicit expressions are found for the scattering length $ a $ and the effective range $ r _ e $ which determine the s - wave scattering of ultracold atoms. the effects on $ a $ and $ r _ e $ of considering the radial coordinate in the interval $ [ 0, \ infty ) $ or in the extended region $ ( - \ infty, \ infty ) $ are studied in detail.
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arxiv:1203.1285
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person reidentification ( reid ) refers to the task of verifying the identity of a pedestrian observed from nonoverlapping views in a surveillance camera network. it has recently been validated that reranking can achieve remarkable performance improvements in person reid systems. however, current reranking approaches either require feedback from users or suffer from burdensome computational costs. in this paper, we propose to exploit a density - adaptive smooth kernel technique to achieve efficient and effective reranking. specifically, we adopt a smooth kernel function to formulate the neighbor relationships among data samples with a density - adaptive parameter. based on this new formulation, we present two simple yet effective reranking methods, termed \ emph { inverse } density - adaptive kernel based reranking ( inv - dakr ) and \ emph { bidirectional } density - adaptive kernel based reranking ( bi - dakr ), in which the local density information in the vicinity of each gallery sample is elegantly exploited. moreover, we extend the proposed inv - dakr and bi - dakr methods to incorporate the available extra probe samples and demonstrate that when and why these extra probe samples are able to improve the local neighborhood and thus further refine the ranking results. extensive experiments are conducted on six benchmark datasets, including : prid450s, viper, cuhk03, grid, market - 1501 and mars. the experimental results demonstrate that our proposals are effective and efficient.
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arxiv:1805.07698
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this work introduces weaver, our first family of large language models ( llms ) dedicated to content creation. weaver is pre - trained on a carefully selected corpus that focuses on improving the writing capabilities of large language models. we then fine - tune weaver for creative and professional writing purposes and align it to the preference of professional writers using a suit of novel methods for instruction data synthesis and llm alignment, making it able to produce more human - like texts and follow more diverse instructions for content creation. the weaver family consists of models of weaver mini ( 1. 8b ), weaver base ( 6b ), weaver pro ( 14b ), and weaver ultra ( 34b ) sizes, suitable for different applications and can be dynamically dispatched by a routing agent according to query complexity to balance response quality and computation cost. evaluation on a carefully curated benchmark for assessing the writing capabilities of llms shows weaver models of all sizes outperform generalist llms several times larger than them. notably, our most - capable weaver ultra model surpasses gpt - 4, a state - of - the - art generalist llm, on various writing scenarios, demonstrating the advantage of training specialized llms for writing purposes. moreover, weaver natively supports retrieval - augmented generation ( rag ) and function calling ( tool usage ). we present various use cases of these abilities for improving ai - assisted writing systems, including integration of external knowledge bases, tools, or apis, and providing personalized writing assistance. furthermore, we discuss and summarize a guideline and best practices for pre - training and fine - tuning domain - specific llms.
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arxiv:2401.17268
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non - holonomic constraints, both in the lagragian and hamiltonian formalism, are discussed from the geometrical viewpoint of implicit differential equations. a precise statement of both problems is presented remarking the similarities and differences with other classical problems with constraints. in our discussion, apart from a constraint submanifold, a field of permitted directions and a system of reaction forces are given, the later being in principle unrelated to the constraint submanifold. an implicit differential equation is associated to a non - holonomic problem using the tulczyjew ' s geometrical description of the legendre transformation. the integrable part of this implicit differential equation is extracted using an adapted version of the integrability algorithm. moreover, sufficient conditions are found that guarantees the compatibility of the non - holonomic problem, i. e., that assures that the integrability algorithm stops at first step, and moreover it implies the existence of a vector field whose integral curves are the solutions to the problem. in addition this vector field turns out to be a second order differential equation. these compatibility conditions are shown to include as particular cases many others obtained previously by other authors. several examples and further lines of development of the subject are also discussed.
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arxiv:math-ph/0104021
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the drastic increase of data quantity often brings the severe decrease of data quality, such as incorrect label annotations, which poses a great challenge for robustly training deep neural networks ( dnns ). existing learning \ mbox { methods } with label noise either employ ad - hoc heuristics or restrict to specific noise assumptions. however, more general situations, such as instance - dependent label noise, have not been fully explored, as scarce studies focus on their label corruption process. by categorizing instances into confusing and unconfusing instances, this paper proposes a simple yet universal probabilistic model, which explicitly relates noisy labels to their instances. the resultant model can be realized by dnns, where the training procedure is accomplished by employing an alternating optimization algorithm. experiments on datasets with both synthetic and real - world label noise verify that the proposed method yields significant improvements on robustness over state - of - the - art counterparts.
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arxiv:2101.05467
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a hybrid numerical model previously developed for combustion simulations is extended in this article to describe flame propagation and stabilization in porous media. the model, with a special focus on flame / wall interaction processes, is validated via corresponding benchmarks involving flame propagation in channels with both adiabatic and constant - temperature walls. simulations with different channel widths show that the model can correctly capture the changes in flame shape and propagation speed as well as the dead zone and quenching limit, as found in channels with cold walls. the model is further assessed considering a pseudo 2 - d porous burner involving an array of cylindrical obstacles at constant temperature, investigated in a companion experimental study. furthermore, the model is used to simulate pore - scale flame dynamics in a randomly - generated 3 - d porous media. results are promising, opening the door for future simulations of flame propagation in realistic porous media.
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arxiv:2304.05657
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the quantum approximate optimization algorithm ( qaoa ) is one of the canonical algorithms designed to find approximate solutions to combinatorial optimization problems in current noisy intermediate - scale quantum ( nisq ) devices. it is an active area of research to exhibit its speedup over classical algorithms. the performance of the qaoa at low depths is limited, while the qaoa at higher depths is constrained by the current techniques. we propose a new version of qaoa that incorporates the capabilities of qaoa and the real - space renormalization group transformation, resulting in enhanced performance. numerical simulations demonstrate that our algorithm can provide accurate solutions for certain randomly generated instances utilizing qaoa at low depths, even at the lowest depth. the algorithm is suitable for nisq devices to exhibit a quantum advantage.
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arxiv:2312.06181
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. two special cases of this, which are also involutions, are the bitwise not operation which is xor with an all - ones value, and stream cipher encryption, which is an xor with a secret keystream. this predates binary computers ; practically all mechanical cipher machines implement a reciprocal cipher, an involution on each typed - in letter. instead of designing two kinds of machines, one for encrypting and one for decrypting, all the machines can be identical and can be set up ( keyed ) the same way. another involution used in computers is an order - 2 bitwise permutation. for example. a color value stored as integers in the form ( r, g, b ), could exchange r and b, resulting in the form ( b, g, r ) : f ( f ( rgb ) ) = rgb, f ( f ( bgr ) ) = bgr. = = = physics = = = legendre transformation, which converts between the lagrangian and hamiltonian, is an involutive operation. integrability, a central notion of physics and in particular the subfield of integrable systems, is closely related to involution, for example in context of kramers – wannier duality. = = see also = = atbash automorphism idempotence rot13 = = references = = = = further reading = = ell, todd a. ; sangwine, stephen j. ( 2007 ). " quaternion involutions and anti - involutions ". computers & mathematics with applications. 53 ( 1 ) : 137 – 143. arxiv : math / 0506034. doi : 10. 1016 / j. camwa. 2006. 10. 029. s2cid 45639619. knus, max - albert ; merkurjev, alexander ; rost, markus ; tignol, jean - pierre ( 1998 ), the book of involutions, colloquium publications, vol. 44, with a preface by j. tits, providence, ri : american mathematical society, isbn 0 - 8218 - 0904 - 0, zbl 0955. 16001 " involution ", encyclopedia of mathematics, ems press, 2001 [ 1994 ] = = external links = = media related to involution at wikimedia commons
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https://en.wikipedia.org/wiki/Involution_(mathematics)
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class imbalance is a major problem in many real world classification tasks. due to the imbalance in the number of samples, the support vector machine ( svm ) classifier gets biased toward the majority class. furthermore, these samples are often observed with a certain degree of noise. therefore, to remove these problems we propose a novel fuzzy based approach to deal with class imbalanced as well noisy datasets. we propose two approaches to address these problems. the first approach is based on the intuitionistic fuzzy membership, termed as robust energy - based intuitionistic fuzzy least squares twin support vector machine ( if - relstsvm ). furthermore, we introduce the concept of hyperplane - based fuzzy membership in our second approach, where the final classifier is termed as robust energy - based fuzzy least square twin support vector machine ( f - relstsvm ). by using this technique, the membership values are based on a projection based approach, where the data points are projected on the hyperplanes. the performance of the proposed algorithms is evaluated on several benchmark and synthetic datasets. the experimental results show that the proposed if - relstsvm and f - relstsvm models outperform the baseline algorithms. statistical tests are performed to check the significance of the proposed algorithms. the results show the applicability of the proposed algorithms on noisy as well as imbalanced datasets.
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arxiv:2309.15886
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we propose a lens for atoms with reduced chromatic aberrations and calculate its focal length and spot size. in our scheme a two - level atom interacts with a near - resonant standing light wave formed by two running waves of slightly different wave vectors, and a far - detuned running wave propagating perpendicular to the standing wave. we show that within the raman - nath approximation and for an adiabatically slow atom - light interaction, the phase acquired by the atom is independent of the incident atomic velocity.
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arxiv:1211.7220
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non - gaussianity of the cosmological matter density field can be largely reduced by a local gaussianization transformation ( and its approximations such as the logrithmic transformation ). such behavior can be recasted as the gaussian copula hypothesis, and has been verified to very high accuracy at two - point level. on the other hand, statistically significant non - gaussianities in the gaussianized field have been detected in simulations. we point out that, this apparent inconsistency is caused by the very limited degrees of freedom in the copula function, which make it misleading as a diagnosis of residual non - gaussianity in the gaussianized field. using the copula density, we highlight the departure from gaussianity. we further quantify its impact in the predicted n - point correlation functions. we explore a remedy of the gaussian copula hypothesis, which alleviates but not completely solves the above problems.
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arxiv:2006.06182
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we develop a new dynamical model for high energy heavy - ion collisions in the beam energy region of the highest net - baryon densities on the basis of non - equilibrium microscopic transport model jam and macroscopic 3 + 1d hydrodynamics by utilizing a dynamical initialization method. in this model, dynamical fluidization of a system is controlled by the source terms of the hydrodynamic fields. in addition, time dependent core - corona separation of hot regions is implemented. we show that our new model describes multiplicities and mean transverse mass in heavy - ion collisions within a beam energy region of $ 3 < \ sqrt { s _ { nn } } < 30 $ gev. good agreement of the beam energy dependence of the $ k ^ + / \ pi ^ + $ ratio is obtained, which is explained by the fact that a part of the system is not thermalized in our core - corona approach.
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arxiv:1805.09024
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the interactions between holes in the hubbard model, in the low density, intermediate to strong coupling limit, are investigated. dressed spin polarons in neighboring sites have an increased kinetic energy and an enhanced hopping rate. both effects are of the order of the hopping integral and lead to an effective attraction at intermediate couplings. our results are derived by systematically improving mean field calculations. the method can also be used to derive known properties of isolated spin polarons.
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arxiv:cond-mat/9801157
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we present a mathematica package ampred for the semi - automatic calculations of multi - loop feynman amplitudes with high efficiency and precision. ampred implements the methods of integration by parts and differential equations in the feynman - parameter representation. it allows for the calculations of general parametric integrals ( which may not have momentum - space correspondences ). various user - friendly tools for multi - loop calculations, such as those to construct and solve differential equations for feynman integrals, are provided. it can also deal with tensor algebras in non - relativistic field theories. interfaces to some packages, like qgraf and form, are also provided.
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arxiv:2408.06426
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nonlinear magneto - optics is a very sensitive fingerprint of the electronic, magnetic, and atomic structure of surfaces, interfaces, and thin ferromagnetic films. analyzing theoretically the nonlinear magneto - optical kerr effect for thin films of fe ( 001 ) and at fe surfaces we demonstrate exemplarily how various electronic material properties of ferromagnets, such as the $ d $ - band width, the magnetization, the substrate lattice constant, and the film - thickness dependence can be extracted from the calculated nonlinear kerr spectra. furthermore, we show how the substrate $ d $ electrons ( cu ( 001 ) ) affect the nonlinear kerr spectra even without being themselves spin - polarized and without film - substrate hybridization. we show that the kerr rotation angle in second harmonic generation is enhanced by one to two orders of magnitude compared to the linear kerr angle and how symmetry can be used to obtain the direction of magnetization in thin films and at buried interfaces from nonlinear magneto - optics.
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arxiv:cond-mat/9509013
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we prove the existence of a berezin - engli \ v { s } quantization for cartan - hartogs domains.
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arxiv:1404.1749
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let $ ( \ phi _ t ) $, $ t \ ge 0 $, be a semigroup of holomorphic self - maps of the unit disk $ \ mathbb { d } $. let $ \ omega $ be its koenigs domain and $ \ tau \ in \ partial \ mathbb { d } $ be its denjoy - wolff point. suppose that $ 0 \ in \ omega $ and let $ \ omega ^ \ sharp $ be the steiner symmetrization of $ \ omega $ with respect to the real axis. consider the semigroup $ ( \ phi _ t ^ \ sharp ) $ with koenigs domain $ \ omega ^ \ sharp $ and let $ \ tau ^ \ sharp $ be its denjoy - wolff point. we show that, up to a multiplicative constant, the rate of convergence of $ ( \ phi _ t ^ \ sharp ) $ is slower than that of $ ( \ phi _ t ) $ ; that is, for every $ t > 0 $, $ | \ phi _ t ( 0 ) - \ tau | \ leq 4 \ pi \, | \ phi _ t ^ \ sharp ( 0 ) - \ tau ^ \ sharp | $. the main tool for the proof is the harmonic measure.
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arxiv:2503.20447
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semantic segmentation of aerial videos has been extensively used for decision making in monitoring environmental changes, urban planning, and disaster management. the reliability of these decision support systems is dependent on the accuracy of the video semantic segmentation algorithms. the existing cnn based video semantic segmentation methods have enhanced the image semantic segmentation methods by incorporating an additional module such as lstm or optical flow for computing temporal dynamics of the video which is a computational overhead. the proposed research work modifies the cnn architecture by incorporating temporal information to improve the efficiency of video semantic segmentation. in this work, an enhanced encoder - decoder based cnn architecture ( uvid - net ) is proposed for uav video semantic segmentation. the encoder of the proposed architecture embeds temporal information for temporally consistent labelling. the decoder is enhanced by introducing the feature - refiner module, which aids in accurate localization of the class labels. the proposed uvid - net architecture for uav video semantic segmentation is quantitatively evaluated on extended manipaluavid dataset. the performance metric miou of 0. 79 has been observed which is significantly greater than the other state - of - the - art algorithms. further, the proposed work produced promising results even for the pre - trained model of uvid - net on urban street scene with fine tuning the final layer on uav aerial videos.
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arxiv:2011.14284
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we provide bounds for the product of the lengths of distinguished shortest paths in a finite network induced by a triangulation of a topological planar quadrilateral.
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arxiv:math/0511289
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by modeling the stripe phase in cuprates as spin gapped stripes coupled to the rvb liquid of preformed electron pairs, i derive the low energy effective theory of the rvb phase variable. it is found that the effect of stripe dynamics ( including both longitudinal and transverse modes ) leads to incipient temporal phase stiffness in the rvb liquid, which tunes a quantum phase transition toward a superconducting ground state with global phase order. physical consequences of this quantum criticality are discussed.
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arxiv:cond-mat/0002232
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the importance of finite - size effects for the electronic structure of long zigzag and armchair carbon nanotubes is studied. we analyze the electronic structure of capped ( 6, 6 ), ( 8, 0 ), and ( 9, 0 ) single walled carbon nanotubes as a function of their length up to 60 nm, using a divide and conquer density functional theory approach. for the metallic nanotubes studied, most of the physical features appearing in the density of states of an infinite carbon nanotube are recovered at a length of 40 nm. the ( 8, 0 ) semi - conducting nanotube studied exhibits pronounced edge effects within the energy gap that scale as the inverse of the length of the nanotube. as a result, the energy gap reduces from the value of ~ 1 ev calculated for the periodic system to a value of ~ 0. 25 ev calculated for a capped 62 nm long cnt. these edge effects are expected to become negligible only at tube lengths exceeding 6 micrometers. our results indicate that careful tailoring of the nature of the system and its capping units should be applied when designing new nanoelectronic devices based on carbon nanotubes. these conclusions are expected to hold for other one - dimensional systems such as graphene nanoribbons, conducting polymers, and dna molecules.
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arxiv:physics/0609091
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results are presented of extended and refined optical identification of 181 radio / x - ray sources in the rass - green bank ( rgb ) catalog which have been spectroscopically observed in the sloan digital sky survey ( sdss ) dr5. for 72 sources, the identifications for are presented for the first time. it is confirmed that the majority of strong radio / x - ray emitters are radio - loud active galactic nuclei ( agns ), particularly blazars. taking advantage of the high spectral quality and resolution and our refined spectral modeling, we are able to disentangle narrow line radio galaxies ( nlrgs ), as vaguely termed in most previous identification work, into seyfert ii galaxies and liners, based on the standard emission line diagnostics. the nlrgs in the rgb sample, mostly belonging to ` weak line radio galaxies ', are found have optical spectra consistent predominantly with liners, and only a small fraction with seyfert ii galaxies. a small number of liners have radio power as high as $ 10 ^ { 23 } - 10 ^ { 26 } $ \ whz at 5 ghz, being among the strongest radio emitting liners known so far. two sources are identified with radio - loud narrow line seyfert 1 galaxies ( nls1s ), a class of rare objects. the presence is also confirmed of flat - spectrum radio quasars with the radio - - optical - - x - ray effective spectral indices similar to those of high - energy peaked bl lac ( hbl ), albeit it is yet a debate as to whether this is the case for their actual spectral energy distributions.
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arxiv:0906.1361
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understanding the internal spin structure of the nucleon still remains a challenge in strong interaction physics. transversity, which describes the transverse spin structure of quarks in a transversely polarized proton, is poorly constrained by experimental data. since it is chiral - odd, it can only be accessed through channels that couple to other chiral - odd distributions, like the collins fragmentation functions ( so - called collins effect ) or the interference fragmentation functions. recently, a detailed calculation using the soft - collinear effective theory found that the collins effect in $ pp $ collisions involves a mixture of collinear and transverse momentum dependent ( tmd ) factorization. the collins effect provides a direct probe to the collins fragmentation function and enables testing of its evolution, universality and factorization breaking in the transverse momentum dependent formalism. in 2018, star published the first measurements of collins asymmetries for charged pions in jets in polarized $ pp $ collisions at $ \ sqrt { s } $ = 500 gev based on data taken during 2011. these measurements probe $ q ^ 2 $ scales one to two orders of magnitude larger than similar measurements in semi - inclusive deep - inelastic scattering ( sidis ) and the results are consistent with predictions based on global analyses of $ e ^ { + } e ^ { - } $ and sidis data. in 2012 and 2015, star collected $ \ sim $ 14 $ \ mathrm { pb ^ { - 1 } } $ and $ \ sim $ 52 $ \ mathrm { pb ^ { - 1 } } $ of transversely polarized $ pp $ data at $ \ sqrt { s } $ = 200 gev, respectively. these datasets provide the most precise measurement of the collins effect in 200 gev $ pp $ collisions to date, especially at the quark momentum fractions $ 0. 1 \ le x \ le 0. 4 $. these proceedings present the preliminary results for collins asymmetries of identified pions in jets in $ pp $ collisions at $ \ sqrt { s } $ = 200 gev and comparisons to theory predictions.
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arxiv:2203.00180
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in this paper we study the effects of noise on the bipower variation ( bpv ), realized volatility ( rv ) and testing for co - jumps in high - frequency data under the small noise framework. we first establish asymptotic properties of the bpv in this framework. in the presence of the small noise, the rv is asymptotically biased and the additional asymptotic conditional variance term appears in its limit distribution. we also give feasible estimation methods of the asymptotic conditional variances of the rv. second, we derive the asymptotic distribution of the test statistic proposed in jacod and todorov ( 2009 ) under the presence of small noise for testing the presence of co - jumps in two dimensional it \ ^ o semimartingale. in contrast to the setting in jacod and todorov ( 2009 ), we show that the additional conditional asymptotic variance terms appear, and give consistent estimation procedures for the asymptotic conditional variances in order to make the test feasible. simulation experiments show that our asymptotic results give reasonable approximations in the finite sample cases.
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arxiv:1605.02621
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we present new hst ultraviolet color - magnitude diagrams of 5 massive galactic globular clusters : ngc 2419, ngc 6273, ngc 6715, ngc 6388, and ngc 6441. these observations were obtained to investigate the " blue hook " phenomenon previously observed in uv images of the globular clusters omega cen and ngc 2808. blue hook stars are a class of hot ( approximately 35, 000 k ) subluminous horizontal branch stars that occupy a region of the hr diagram that is unexplained by canonical stellar evolution theory. by coupling new stellar evolution models to appropriate non - lte synthetic spectra, we investigate various theoretical explanations for these stars. specifically, we compare our photometry to canonical models at standard cluster abundances, canonical models with enhanced helium ( consistent with cluster self - enrichment at early times ), and flash - mixed models formed via a late helium - core flash on the white dwarf cooling curve. we find that flash - mixed models are required to explain the faint luminosity of the blue hook stars, although neither the canonical models nor the flash - mixed models can explain the range of color observed in such stars, especially those in the most metal - rich clusters. aside from the variation in the color range, no clear trends emerge in the morphology of the blue hook population with respect to metallicity.
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arxiv:1006.1591
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since the advent of chatbots in the commercial sector, they have been widely employed in the customer service department. typically, these commercial chatbots are retrieval - based, so they are unable to respond to queries absent in the provided dataset. on the contrary, generative chatbots try to create the most appropriate response, but are mostly unable to create a smooth flow in the customer - bot dialog. since the client has few options left for continuing after receiving a response, the dialog becomes short. through our work, we try to maximize the intelligence of a simple conversational agent so it can answer unseen queries, and generate follow - up questions or remarks. we have built a chatbot for a jewelry shop that finds the underlying objective of the customer ' s query by finding similarity of the input to patterns in the corpus. our system features an audio input interface for clients, so they may speak to it in natural language. after converting the audio to text, we trained the model to extract the intent of the query, to find an appropriate response and to speak to the client in a natural human voice. to gauge the system ' s performance, we used performance metrics such as recall, precision and f1 score.
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arxiv:2206.04659
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let $ w $ be a random positive definite symmetric matrix distributed according to a real wishart distribution and let $ w ^ { - 1 } = ( w ^ { ij } ) _ { i, j } $ be its inverse matrix. we compute general moments $ \ mathbb { e } [ w ^ { k _ 1 k _ 2 } w ^ { k _ 3 k _ 4 }... w ^ { k _ { 2n - 1 } k _ { 2n } } ] $ explicitly. to do so, we employ the orthogonal weingarten function, which was recently introduced in the study for haar - distributed orthogonal matrices. as applications, we give formulas for moments of traces of a wishart matrix and its inverse.
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arxiv:1004.4717
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image description task has been invariably examined in a static manner with qualitative presumptions held to be universally applicable, regardless of the scope or target of the description. in practice, however, different viewers may pay attention to different aspects of the image, and yield different descriptions or interpretations under various contexts. such diversity in perspectives is difficult to derive with conventional image description techniques. in this paper, we propose a customized image narrative generation task, in which the users are interactively engaged in the generation process by providing answers to the questions. we further attempt to learn the user ' s interest via repeating such interactive stages, and to automatically reflect the interest in descriptions for new images. experimental results demonstrate that our model can generate a variety of descriptions from single image that cover a wider range of topics than conventional models, while being customizable to the target user of interaction.
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arxiv:1805.00460
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interpreting the excesses around 750 gev in the diphoton spectra to be the signal of a new heavy scalar decaying to photons, we point out the possibility of looking for correlated signals with virtual photons. in particular, we emphasize that the effective operator that generates the diphoton decay will also generate decays to two leptons and a photon, as well as to four leptons, independently of the new resonance couplings to $ z \ gamma $ and $ zz $. depending on the relative sizes of these effective couplings, we show that the virtual diphoton component can make up a sizable, and sometimes dominant, contribution to the total $ 2 \ ell \ gamma $ and $ 4 \ ell $ partial widths. we also discuss modifications to current experimental cuts in order to maximize the sensitivity to these virtual photon effects. finally, we briefly comment on prospects for channels involving other standard model fermions as well as more exotic decay possibilities of the putative resonance.
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arxiv:1601.02004
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we consider maximum likelihood estimation for both causal and noncausal autoregressive time series processes with non - gaussian $ \ alpha $ - stable noise. a nondegenerate limiting distribution is given for maximum likelihood estimators of the parameters of the autoregressive model equation and the parameters of the stable noise distribution. the estimators for the autoregressive parameters are $ n ^ { 1 / \ alpha } $ - consistent and converge in distribution to the maximizer of a random function. the form of this limiting distribution is intractable, but the shape of the distribution for these estimators can be examined using the bootstrap procedure. the bootstrap is asymptotically valid under general conditions. the estimators for the parameters of the stable noise distribution have the traditional $ n ^ { 1 / 2 } $ rate of convergence and are asymptotically normal. the behavior of the estimators for finite samples is studied via simulation, and we use maximum likelihood estimation to fit a noncausal autoregressive model to the natural logarithms of volumes of wal - mart stock traded daily on the new york stock exchange.
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arxiv:0908.1895
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a key advantage of recurrent neural networks ( rnns ) over transformers is their linear computational and space complexity enables faster training and inference for long sequences. however, rnns are fundamentally unable to randomly access historical context, and simply integrating attention mechanisms may undermine their efficiency advantages. to overcome this limitation, we propose \ textbf { h } ierarchical \ textbf { s } parse \ textbf { a } ttention ( hsa ), a novel attention mechanism that enhances rnns with long - range random access flexibility while preserving their merits in efficiency and length generalization. hsa divides inputs into chunks, selecting the top - $ k $ chunks and hierarchically aggregates information. the core innovation lies in learning token - to - chunk relevance based on fine - grained token - level information inside each chunk. this approach enhances the precision of chunk selection across both in - domain and out - of - domain context lengths. to make hsa efficient, we further introduce a hardware - aligned kernel design. by combining hsa with mamba, we introduce ramba, which achieves perfect accuracy in passkey retrieval across 64 million contexts despite pre - training on only 4k - length contexts, and significant improvements on various downstream tasks, with nearly constant memory footprint. these results show ramba ' s huge potential in long - context modeling.
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arxiv:2504.16795
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we construct new axially symmetric rotating solutions of einstein - yang - mills - higgs theory. these globally regular configurations possess a nonvanishing electric charge which equals the total angular momentum, and zero topological charge, representing a monopole - antimonopole system rotating around the symmetry axis through their common center of mass.
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arxiv:hep-th/0412011
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long range wide area networks ( lorawan ) technology provides a simple solution to enable low - cost services for low power internet - of - things ( iot ) networks in various applications. the current evaluation of lorawan networks relies on simulations or early testing, which are typically time consuming and prevent effective exploration of the design space. this paper proposes an analytical model to calculate the delay and energy consumed for reliable uplink ( ul ) data delivery in class a lorawan. the analytical model is evaluated using a real network test - bed as well as simulation experiments based on the ns - 3 lorawan module. the resulting comparison confirms that the model accurately estimates the delay and energy consumed in the considered environment. the value of the model is demonstrated via its application to evaluate the impact of the number of end - devices and the maximum number of data frame retransmissions on delay and energy consumed for the confirmed ul data delivery in lorawan networks. the model can be used to optimize different transmission parameters in future lorawan networks.
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arxiv:2009.09397
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this paper addresses the problem of designing ldpc decoders robust to transient errors introduced by a faulty hardware. we assume that the faulty hardware introduces errors during the message passing updates and we propose a general framework for the definition of the message update faulty functions. within this framework, we define symmetry conditions for the faulty functions, and derive two simple error models used in the analysis. with this analysis, we propose a new interpretation of the functional density evolution threshold previously introduced, and show its limitations in case of highly unreliable hardware. however, we show that under restricted decoder noise conditions, the functional threshold can be used to predict the convergence behavior of faids under faulty hardware. in particular, we reveal the existence of robust and non - robust faids and propose a framework for the design of robust decoders. we finally illustrate robust and non - robust decoders behaviors of finite length codes using monte carlo simulations.
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arxiv:1410.2291
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simulation models have been informing the covid - 19 policy - making process. these models, therefore, have significant influence on risk of societal harms. but how clearly are the underlying modelling assumptions and limitations communicated so that decision - makers can readily understand them? when making claims about risk in safety - critical systems, it is common practice to produce an assurance case, which is a structured argument supported by evidence with the aim to assess how confident we should be in our risk - based decisions. we argue that any covid - 19 simulation model that is used to guide critical policy decisions would benefit from being supported with such a case to explain how, and to what extent, the evidence from the simulation can be relied on to substantiate policy conclusions. this would enable a critical review of the implicit assumptions and inherent uncertainty in modelling, and would give the overall decision - making process greater transparency and accountability.
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arxiv:2005.08381
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the nonlinear schr \ " odinger / gross - pitaevskii ( nls / gp ) equation is considered in the presence of three equally - spaced potentials. the problem is reduced to a finite - dimensional hamiltonian system by a galerkin truncation. families of oscillatory orbits are sought in the neighborhoods of the system ' s nine branches of standing wave solutions. normal forms are computed in the neighborhood of these branches ' various hamiltonian hopf and saddle - node bifurcations, showing how the oscillatory orbits change as a parameter is increased. numerical experiments show agreement between normal form theory and numerical solutions to the reduced system and nls / gp near the hamiltonian hopf bifurcations and some subtle disagreements near the saddle - node bifurcations due to exponentially small terms in the asymptotics.
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arxiv:1612.02041
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behavioural cloning uses a dataset of demonstrations to learn a behavioural policy. to overcome various learning and policy adaptation problems, we propose to use latent space to index a demonstration dataset, instantly access similar relevant experiences, and copy behavior from these situations. actions from a selected similar situation can be performed by the agent until representations of the agent ' s current situation and the selected experience diverge in the latent space. thus, we formulate our control problem as a search problem over a dataset of experts ' demonstrations. we test our approach on basalt minerl - dataset in the latent representation of a video pretraining model. we compare our model to state - of - the - art minecraft agents. our approach can effectively recover meaningful demonstrations and show human - like behavior of an agent in the minecraft environment in a wide variety of scenarios. experimental results reveal that performance of our search - based approach is comparable to trained models, while allowing zero - shot task adaptation by changing the demonstration examples.
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arxiv:2306.09082
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the stability conditions for the singular vortex which accompanies majorana zero modes at the core are investigated for p - wave resonant superfluids of atomic fermi gases. within the ginzburg - landau framework we determine the stable conditions in the parameter space for the external rotation frequency and the harmonic trap frequency. there exists the narrow stable region in this parameter space for quasi - two - dimensional condensates. we also describe the detailed characterizations of the spatial structure of the order parameter in the chiral p - wave superfluids under rotation.
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arxiv:0911.2964
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motivated by the increasing availability of vehicle trajectory data, we propose learn - to - route, a comprehensive trajectory - based routing solution. specifically, we first construct a graph - like structure from trajectories as the routing infrastructure. second, we enable trajectory - based routing given an arbitrary ( source, destination ) pair. in the first step, given a road network and a collection of trajectories, we propose a trajectory - based clustering method that identifies regions in a road network. if a pair of regions are connected by trajectories, we maintain the paths used by these trajectories and learn a routing preference for travel between the regions. as trajectories are skewed and sparse, many region pairs are not connected by trajectories. we thus transfer routing preferences from region pairs with sufficient trajectories to such region pairs and then use the transferred preferences to identify paths between the regions. in the second step, we exploit the above graph - like structure to achieve a comprehensive trajectory - based routing solution. empirical studies with two substantial trajectory data sets offer insight into the proposed solution, indicating that it is practical. a comparison with a leading routing service offers evidence that the paper ' s proposal is able to enhance routing quality. this is an extended version of " learning to route with sparse trajectory sets " [ 1 ], to appear in ieee icde 2018.
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arxiv:1802.07980
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we have obtained keck spectra of six candidate globular clusters ( gcs ) in the dynamically young elliptical galaxy ngc 3610, supplementing our previous keck spectra of eight confirmed gcs ( strader et al. 2003 ). five of our new candidates are confirmed to be gcs. of the thirteen gcs, eleven are located within the k band effective radius of 7 kpc. two of these thirteen clusters are found to be young ( ~ 2 gyr ) and very metal - rich ( [ z / h ] ~ + 0. 5 ), three are old and metal - poor, and the remaining eight clusters are old and metal - rich. the ages of the young clusters are consistent with a recent spectroscopic age estimate of 1. 6 + / - 0. 5 gyr for the galaxy itself ( denicolo et al. 2003 ) and suggest that these clusters formed in the disk - disk merger which likely created ngc 3610. intriguingly, both young gcs have [ alpha / fe ] ~ + 0. 3, while the majority of the old clusters are not alpha - enhanced, in contrast to galactic and m31 gcs, and contrary to predictions of nucleosynthetic calculations. the two old subpopulations of gcs can be attributed to the merger progenitors. the relative numbers of old and new metal - rich gcs are poorly constrained because of the expected differences in radial distributions of the two subpopulations. however, based on our spectroscopic results and a comparison of the hubble space telescope color magnitude diagram ( whitmore et al. 2002 ) with stellar population models, we argue that more than half of the metal - rich gcs are likely to be old.
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arxiv:astro-ph/0310611
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we prove the transportation inequality with the uniform norm for the laws of diffusion processes with lipschitz and / or dissipative coefficients and apply them to some singular stochastic differential equations of interest.
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arxiv:1009.5251
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we present a family of selfinjective algebras of type d, which arise from the 3 - preprojective algebras of type a by taking a $ \ mathbb { z } _ 3 $ - quotient. we show that a subset of these are themselves 3 - preprojective algebras, and that the associated 2 - representation - finite algebras are fractional calabi - yau. in addition, we show our work is connected to modular invariants for su ( 3 ).
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arxiv:2403.14285
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local correlation entropy, introduced by takens in 1983, represents the exponential decay rate of the relative frequency of recurrences in the trajectory of a point, as the embedding dimension grows to infinity. in this paper we study relationship between the supremum of local correlation entropies and the topological entropy. for dynamical systems on graphs we prove that the two quantities coincide. moreover, there is an uncountable set of points with local correlation entropy arbitrarily close to the topological entropy. on the other hand, we construct a strictly ergodic subshift with positive topological entropy having all local correlation entropies equal to zero. as a necessary tool, we derive an expected relationship between the local correlation entropies of a system and those of its iterates.
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arxiv:1612.02592
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the de - excited energy of electron capture ( ec ) induced by magnetic field decay may be a new source for heating magnetar crust, so we do a quantitative calculation on the ec process near the outer crust and analyze their influence on persistent x - ray radiation of magnetars, adopting the experimental data or the results of theoretical model ( including the large - scale shell model and quasi - particle random phase approximation ).
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arxiv:1309.3782
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verlinde argued \ cite { verlinde : 2016toy } that baryonic matter in de sitter universe with a hubble constant $ h $ produces a bulk contribution to the vacuum entanglement entropy $ \ delta s _ { ent } $. using the de sitter temperature $ t _ { ds } = \ frac { h } { 2 \ pi } $, he interpreted $ \ delta m $ in the first law $ t _ { ds } \ \ delta s _ { ent } = - \ delta m $ with the dark matter energy. we use standard tools of the gauge / gravity correspondence to present some evidence for the verlinde ' s proposal.
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arxiv:1702.08590
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we show that nonlinear response of a quantum oscillator displays antiresonant dips and resonant peaks with varying frequency of the driving field. the effect is a consequence of special symmetry and is related to resonant multiphoton mixing of several pairs of oscillator states at a time. we also discuss escape from a metastable state of forced vibrations. two important examples show that the probability of escape via diffusion over quasienergy is larger than via dynamical tunneling provided the relaxation rate exceeds both of them. diffusion dominates even for zero temperature, so that escape occurs via quantum rather than thermal activation. the effects can be studied using josephson junctions and josephson - junction based systems.
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arxiv:quant-ph/0507261
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we introduce joint probability trees ( jpt ), a novel approach that makes learning of and reasoning about joint probability distributions tractable for practical applications. jpts support both symbolic and subsymbolic variables in a single hybrid model, and they do not rely on prior knowledge about variable dependencies or families of distributions. jpt representations build on tree structures that partition the problem space into relevant subregions that are elicited from the training data instead of postulating a rigid dependency model prior to learning. learning and reasoning scale linearly in jpts, and the tree structure allows white - box reasoning about any posterior probability $ p ( q | e ) $, such that interpretable explanations can be provided for any inference result. our experiments showcase the practical applicability of jpts in high - dimensional heterogeneous probability spaces with millions of training samples, making it a promising alternative to classic probabilistic graphical models.
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arxiv:2302.07167
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we report a general macroscopic theory for the electrodynamic response of semi - infinite metals ( sims ). the theory includes the hitherto overlooked capacitive effects due to the finite spatial extension of a surface. the basic structure of this theory is independent of the particulars of electron dynamics. analytical expressions have been obtained of the charge density - density response function, which is naturally parsed into two parts. one of them represents a bulk property while the other a pure surface property. we apply the theory to study the responses according to several electronic dynamics models and provide a unified view of their validity and limitations. the models studied include the local dielectric model ( dm ), the dispersive hydrodynamic model ( hdm ) and specular reflection model ( srm ), as well as the less common semi - classical model ( scm ) based on boltzmann ' s transport equation. we show that, in terms of their basic equations, the srm is an extension of the hdm, just as the hdm is an extension of the dm. the scm improves over the srm critically through the inclusion of translation symmetry breaking and surface roughness effects. we then employ the response function to evaluate the so - called dynamical structure factor, which plays an important role in particle scattering. as expected, this factor reveals a peak due to the excitation of surface plasma waves ( spws ). surprisingly, however, the peak is shown to be considerably sharper in the scm than in other models, indicating an incipient instability of the system according to this model. we also study the distribution of charges induced by a charged particle grazing over a sim surface at constant speed. this distribution is shown to contain model - specific features that are of immediate experimental interest.
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arxiv:1806.08308
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life - centred design decenters humans and considers all life and the far - reaching impacts of design decisions. however, little is known about the application of life - centred design tools in practice and their usefulness and limitations for con - sidering more - than - human perspectives. to address this gap, we carried out a se - ries of workshops, reporting on findings from a first - person study involving one design academic and three design practitioners. using a popular flat - pack chair as a case study, we generatively identified and applied four tools : systems maps, actant maps, product lifecycle maps and behavioural impact canvas. we found that the tools provided a structured approach for practising systems thinking, identifying human and non - human actors, understanding their interconnected - ness, and surfacing gaps in the team ' s knowledge. based on the findings, the pa - per proposes a process for implementing life - centred design tools in design pro - jects.
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arxiv:2404.15636
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we optimize a collision - induced cooling process for ultracold atoms in the nondegenerate regime. it makes use of a feshbach resonance, instead of rf radiation in evaporative cooling, to selectively expel hot atoms from a trap. using functional minimization we analytically show that for the optimal cooling process the resonance energy must be tuned such that it linearly follows the temperature. here, optimal cooling is defined as maximizing the phase - space density after a fixed cooling duration. the analytical results are confirmed by numerical monte - carlo simulations. in order to simulate more realistic experimental conditions, we show that background losses do not change our conclusions, while additional non - resonant two - body losses make a lower initial resonance energy with non - linear dependence on temperature preferable.
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arxiv:1412.8473
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hybrid probabilistic logic programs can represent several scenarios thanks to the expressivity of logic programming extended with facts representing discrete and continuous distributions. the semantics for this type of programs is crucial since it ensures that a probability can be assigned to every query. here, following one recent semantics proposal, we illustrate a concrete syntax, and we analyse the syntactic requirements needed to preserve the well - definedness.
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arxiv:2109.08283
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two - dimensional semiconducting transition metal dichalcogenides ( tmdcs ) like molybdenum disulfide ( mos2 ) are generating significant excitement due to their unique electronic, chemical, and optical properties. covalent chemical functionalization represents a critical tool for tuning the properties of tmdcs for use in many applications. however, the chemical inertness of semiconducting tmdcs has thus far hindered the robust chemical functionalization of these materials. previous reports have required harsh chemical treatments or converting tmdcs into metallic phases prior to covalent attachment. here, we demonstrate the direct covalent functionalization of the basal planes of unmodified semiconducting mos2 using aryl diazonium salts without any pretreatments. our approach preserves the semiconducting properties of mos2, results in covalent c - s bonds, is applicable to mos2 derived from a range of different synthesis methods, and enables a range of different functional groups to be tethered directly to the mos2 surface. using density functional theory calculations including van der waals interactions and atomic - scale scanning probe microscopy studies, we demonstrate a novel reaction mechanism in which cooperative interactions enable the functionalization to propagate along the mos2 basal plane. the flexibility of this covalent chemistry employing the diverse aryl diazonium salt family is further exploited to tether active proteins to mos2, suggesting future biological applications and demonstrating its use as a versatile and powerful chemical platform for enhancing the utility of semiconducting tmdcs
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arxiv:1802.09818
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the last few years have seen an explosion of interest in hydrodynamic effects in interacting electron systems in ultra - pure materials. one such material, graphene, is not only an excellent platform for the experimental realization of the hydrodynamic flow of electrons, but also allows for a controlled derivation of the hydrodynamic equations on the basis of kinetic theory. the resulting hydrodynamic theory of electronic transport in graphene yields quantitative predictions for experimentally relevant quantities, e. g. viscosity, electrical conductivity, etc. here i review recent theoretical advances in the field, compare the hydrodynamic theory of charge carriers in graphene with relativistic hydrodynamics and recent experiments, and discuss applications of hydrodynamic approach to novel materials beyond graphene.
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arxiv:2207.10004
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we study integrable systems on double lie algebras in absence of ad - invariant bilinear form by passing to the semidirect product with the $ \ tau $ - representation. we show that in this stage a natural ad - invariant bilinear form does exist, allowing for a straightforward application of the aks theory, and giving rise to manin triple structure, thus bringing the problem to the realm of lie bialgebras and poisson - lie groups.
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arxiv:1405.4340
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we report the first results of star counts carried out with the national astronomical observatories ( naoc ) 60 / 90 cm schmidt telescope in 15 intermediate - band filters from 3000 to 10000 { \ aa } in the batc survey. we analyze a sample of over 1400 main sequence stars ( $ 14 \ le $ v $ \ le21 $ ), which lie in the field with central coordinates r. a. = $ 09 ^ h53 ^ m13 ^ s. 30 $ and dec = 47 $ ^ \ circ49 ^ { \ prime } 00 ^ { \ prime \ prime }. 0 $ ( j2000 ). the field of view is 0. 95 deg $ ^ { 2 } $, and the spatial scale was $ 1 \ arcsec. 67 $. in our model, the distribution of stars perpendicular to the plane of the galaxy is given by two exponential disks ( thin disk plus thick disk ) and a de vaucouleurs halo. based on star counts, we derive the scale heights of the thin disk to be $ 320 ^ { + 14 } _ { - 15 } $ pc and of the thick disk to be $ 640 ^ { + 30 } _ { - 32 } $ pc, respectively, with a local density of $ 7. 0 \ pm1 % $ of the thin disk. we find that the observed counts support an axial ratio of $ c / a \ le0. 6 $ for a de vaucouleurs $ r ^ { 1 / 4 } $ law, implying a more flattened halo. we also derive the stellar luminosity function ( slf ) for the thin disk, and it partly agrees with the hipparcos luminosity function.
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arxiv:astro-ph/0304431
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depth - averaged shallow water models are widely used for the large - scale simulation of tidal turbine arrays. the relatively low computational complexity of this approach allows for layout optimisations aimed at improving the total array power output as well as an assessment of large - scale environmental impacts. in order to assess the suitability of using depth - averaged models to optimise array configurations, a comprehensive comparison between the wake profiles and power outputs predicted by a 2d shallow water model and a 3d actuator disc momentum ( adm ) model is presented. initially, a viscosity sensitivity analysis is presented to outline the limitations associated with using a constant eddy viscosity in the depth - averaged model and to outline the importance of correctly calibrating this value in line with the freestream velocity magnitude. thereafter, the depth - averaged opentidalfarm ( otf ) tool is used to optimise the positions of an array of 32 turbines in an ideal channel and the 3d fluidity adm - rans model is used to assess the accuracy of the otf predictions for the first time. it is shown that with the help of corrected power calculations a good agreement between the two models can be achieved, thus demonstrating the value of the eddy viscosity calibration implemented in the depth - averaged model.
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arxiv:1810.09827
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we investigate the morphology and mechanics of a naturally curved elastic arch loaded at its center and frictionally supported at both ends on a flat, rigid substrate. through systematic numerical simulations, we classify the observed behaviors of the arch into three distinct types of configurations in terms of the arch geometry and the coefficient of static friction with the substrate. a linear theory is developed based on a planar elastica model combined with amontons - coulomb ' s frictional law, which quantitatively explains the numerically constructed phase diagram. the snapping transition of a loaded arch in a sufficiently large indentation regime, which involves a discontinuous force jump, is numerically observed. the proposed model problem allows a fully analytical investigation and demonstrates a rich variety of mechanical behaviors owing to the interplay between elasticity, geometry, and friction. this study provides a basis for understanding more common but complex systems, such as a cylindrical shell subjected to a concentrated load and simultaneously supported by frictional contact with surrounding objects.
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arxiv:2311.11504
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we give a precise and concise formulation of the orientifold construction in type ii superstring theory. our results include anomaly cancellation on the worldsheet and a spacetime computation of the background ramond - ramond charge.
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arxiv:0906.0795
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small - field inflation ( sfi ) is widely considered to be unnatural because an extreme fine - tuning of the initial condition is necessary for sufficiently large e - folding. in this paper, we show that the unnaturally - looking initial condition can be dynamically realised without any fine - tuning if the sfi occurs after rapid oscillations of the inflaton field and particle creations by preheating. in fact, if the inflaton field $ \ phi $ is coupled to another scalar field $ \ chi $ through the interaction $ g ^ 2 \ chi ^ 2 \ phi ^ 2 $ and the vacuum energy during the small field inflation is given by $ \ lambda m ^ 4 $, the initial value can be dynamically set at $ ( \ sqrt { \ lambda } / g ) m ^ 2 / m _ { \ rm pl } $, which is much smaller than the typical scale of the potential $ m. $ this solves the initial condition problem in the new inflation model or some classes of the hilltop inflation models.
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arxiv:1511.05923
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this thesis proposes techniques aiming to make blockchain technologies and smart contract platforms practical by improving their scalability, latency, and privacy. this thesis starts by presenting the design and implementation of chainspace, a distributed ledger that supports user defined smart contracts and execute user - supplied transactions on their objects. the correct execution of smart contract transactions is publicly verifiable. chainspace is scalable by sharding state ; it is secure against subsets of nodes trying to compromise its integrity or availability properties through byzantine fault tolerance ( bft ). this thesis also introduces a family of replay attacks against sharded distributed ledgers targeting cross - shard consensus protocols ; they allow an attacker, with network access only, to double - spend resources with minimal efforts. we then build byzcuit, a new cross - shard consensus protocol that is immune to those attacks and that is tailored to run at the heart of chainspace. next, we propose fastpay, a high - integrity settlement system for pre - funded payments that can be used as a financial side - infrastructure for chainspace to support low - latency retail payments. this settlement system is based on byzantine consistent broadcast as its core primitive, foregoing the expenses of full atomic commit channels ( consensus ). the resulting system has extremely low - latency for both confirmation and payment finality. finally, this thesis proposes coconut, a selective disclosure credential scheme supporting distributed threshold issuance, public and private attributes, re - randomization, and multiple unlinkable selective attribute revelations. it ensures authenticity and availability even when a subset of credential issuing authorities are malicious or offline, and natively integrates with chainspace to enable a number of scalable privacy - preserving applications.
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arxiv:2102.12273
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, the blue sgb, and the faint bss, respectively.
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arxiv:astro-ph/0308469
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methane brown dwarfs, i. e. objects similar to the low mass star gliese 229b, are characterized by very unusual colours : j - k < ~ 0 and i - j > ~ 5. an analysis of the eso public images, which cover an area of 37 sq. arcmin in the three filters, yields one clear methane dwarf candidate with j = 20. 2 and two fainter sources with j ~ = 23. the resulting observed density of methane dwarfs ranges from ~ 100 to ~ 500 objects per sq. degree with j < 23. 1, quite high but compatible, within the errors, with what we derive from simulations of the stellar population of brown dwarfs in the disk of the galaxy adopting reasonable ( although still speculative ) hypotheses on the evolution of bd colours with cooling. the predictions presented here can be useful in constraining the results from future searches of these objects in the infrared. deep imaging of several sq. degrees of sky down to j ~ = 22, k ~ = 22 and i > ~ 27 are necessary to significantly improve the observational database.
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arxiv:astro-ph/9910051
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in this work, a novel approach for the detection and localisation of nonlinear guided waves often associated with the presence of damage in structural components is proposed. the method is active and consists of a piezoelectric transducer bonded to the inspected structure exciting a narrow frequency band wave packet and sensors placed at the proposed ultrasonic devices with embedded phononic crystals. unit cells of phononic crystals are optimized to open a band gap at the excitation frequency so that the excited waves are attenuated, while the sensitivity detection of higher harmonics is increased. the proposed approach is tested numerically and validated experimentally by considering various manufacturing methods, materials, and unit cell geometries. a parametric study of the angle of attachment of the ultrasonic devices with the embedded phononic crystals to the inspected structure is performed. band gaps and filtering capabilities of several prototypes are tested. numerical simulations of guided wave propagation that include the effect of delamination clapping proved that the proposed designs are sensitive enough to detect higher harmonics by simple signal thresholding. the most promising prototype is tested experimentally showing its capability of detection and localisation of a simulated damage.
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arxiv:2406.17370
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timed basic parallel processes ( tbpp ) extend communication - free petri nets ( aka. bpp or commutative context - free grammars ) by a global notion of time. tbpp can be seen as an extension of timed automata ( ta ) with context - free branching rules, and as such may be used to model networks of independent timed automata with process creation. we show that the coverability and reachability problems ( with unary encoded target multiplicities ) are pspace - complete and exptime - complete, respectively. for the special case of 1 - clock tbpp, both are np - complete and hence not more complex than for untimed bpp. this contrasts with known super - ackermannian - completeness and undecidability results for general timed petri nets. as a result of independent interest, and basis for our np upper bounds, we show that the reachability relation of 1 - clock ta can be expressed by a formula of polynomial size in the existential fragment of linear arithmetic, which improves on recent results from the literature.
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arxiv:1907.01240
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in this paper a proposal is made of an adaptive coupling function for achieving synchronization between two lasers subject to optical feedback. such a control scheme requires knowledge of the systems ' parameters. for the first time we demonstrate that when these parameters are not available on - line parameter estimation can be applied. generalisation of the approach to the multi - feedback systems is also presented.
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arxiv:nlin/0404053
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matrix completion is an important area of research in recommender systems. recent methods view a rating matrix as a user - item bi - partite graph with labeled edges denoting observed ratings and predict the edges between the user and item nodes by using the graph neural network ( gnn ). despite their effectiveness, they treat each rating type as an independent relation type and thus cannot sufficiently consider the ordinal nature of the ratings. in this paper, we explore a new approach to exploit rating ordinality for gnn, which has not been studied well in the literature. we introduce a new method, called rogmc, to leverage rating ordinality in gnn - based matrix completion. it uses cumulative preference propagation to directly incorporate rating ordinality in gnn ' s message passing, allowing for users ' stronger preferences to be more emphasized based on inherent orders of rating types. this process is complemented by interest regularization which facilitates preference learning using the underlying interest information. our extensive experiments show that rogmc consistently outperforms the existing strategies of using rating types for gnn. we expect that our attempt to explore the feasibility of utilizing rating ordinality for gnn may stimulate further research in this direction.
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arxiv:2403.04504
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we revisited a model for charmonium hybrid meson with a magnetic gluon [ yu. s. kalashnikova and a. v. nefediev, phys. rev. d { \ bf 77 }, 054025 ( 2008 ) ] and improved the numerical calculations. these improvements support the hybrid meson interpretation of x ( 4260 ). within the same model, we computed the hybrid meson mass with an electric gluon which is resolved to be lighter. relativistic effects and coupling channels decreased also the mass.
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arxiv:0903.1547
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we present and develop a recursion scheme to construct joint eigenfunctions for the commuting analytic difference operators associated with the integrable n - particle systems of hyperbolic relativistic calogero - moser type. the scheme is based on kernel identities we obtained in previous work. in this first paper of a series we present the formal features of the scheme, show explicitly its arbitrary - n viability for the ` free ' cases, and supply the analytic tools to prove the joint eigenfunction properties in suitable holomorphy domains.
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arxiv:1206.3787
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we propose a one - dimensional ( 1d ) diffusion equation ( heat equation ) for systems in which the diffusion constant ( thermal diffusivity ) varies alternately with a spatial period $ a $. we solve the time evolution of the field ( temperature ) profile from a given initial distribution, by diagonalising the hamiltonian, i. e., the laplacian with alternating diffusion constants, and expanding the temperature profile by its eigenstates. we show that there are basically phases with or without edge states. the edge states affect the heat conduction around heat baths. in particular, rapid heat transfer to heat baths would be observed in a short time regime, which is estimated to be $ t < 10 ^ { - 2 } $ s for $ a \ sim 10 ^ { - 3 } $ m system and $ t < 1 $ s for $ a \ sim 10 ^ { - 2 } $ m system composed of two kinds of familiar metals such as titanium, zirconium and aluminium, gold, etc. we also discuss the effective lattice model which simplifies the calculation of edge states up to high energy. it is suggested that these high energy edge states also contribute to very rapid heat conduction in a very short time regime.
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arxiv:2106.09945
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this study aims to reveal what kind of topics emerged in the biomedical domain by retrospectively analyzing newly added mesh ( medical subject headings ) terms from 2001 to 2010 and how they have been used for indexing since their inclusion in the thesaurus. the goal is to investigate if the future trend of a new topic depends on what kind of topic it is without relying on external indicators such as growth, citation patterns, or word co - occurrences. this topic perspective complements the traditional publication perspective in studying emerging topics. results show that topic characteristics, including topic category, clinical significance, and if a topic has any narrower terms at the time of inclusion, influence future popularity of a new mesh. four emergence trend patterns are identified, including emerged and sustained, emerged not sustained, emerged and fluctuated, and not yet emerged. predictive models using topic characteristics for emerging topic prediction show promise. this suggests that the characteristics of topics and domain should be considered when predicting future emergence of research topics. this study bridges a gap in emerging topic prediction by offering a topic perspective and advocates for considering topic and domain characteristics as well as economic, medical, and environmental impact when studying emerging topics in the biomedical domain.
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arxiv:2109.06675
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in this paper we study the isomorphism classes of local, artinian, gorenstein k - algebras a whose maximal ideal m satisfies dim _ k ( m ^ 3 / m ^ 4 ) = 1 by means of macaulay ' s inverse system generalizing a recent result by j. elias and m. e. rossi. then we use such results in order to complete the description of the singular locus of the gorenstein locus of the punctual hilbert scheme of degree 11.
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arxiv:1312.2191
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we consider the canonical problem of influence maximization in social networks. since the seminal work of kempe, kleinberg, and tardos, there have been two largely disjoint efforts on this problem. the first studies the problem associated with learning the parameters of the generative influence model. the second focuses on the algorithmic challenge of identifying a set of influencers, assuming the parameters of the generative model are known. recent results on learning and optimization imply that in general, if the generative model is not known but rather learned from training data, no algorithm can yield a constant factor approximation guarantee using polynomially - many samples, drawn from any distribution. in this paper, we design a simple heuristic that overcomes this negative result in practice by leveraging the strong community structure of social networks. although in general the approximation guarantee of our algorithm is necessarily unbounded, we show that this algorithm performs well experimentally. to justify its performance, we prove our algorithm obtains a constant factor approximation guarantee on graphs generated through the stochastic block model, traditionally used to model networks with community structure.
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arxiv:1801.07355
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the temperature dependence of the interlayer electrical and thermal resistivity in a layered metal are calculated for fermi liquid quasiparticles which are scattered inelastically by two - dimensional antiferromagnetic spin fluctuations. both resistivities have a linear temperature dependence over a broad temperature range. extrapolations to zero temperature made from this linear - $ t $ range give values that appear to violate the wiedemann - franz law. however, below a low - temperature scale, which becomes small close to the critical point, a recovery of this law occurs. our results describe recent measurements on cecoin $ _ 5 $ near a magnetic field - induced quantum phase transition. hence, the experiments do not necessarily imply a non - fermi liquid ground state.
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arxiv:0809.2499
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in this paper, phase transition of ads black holes in lorentz breaking massive gravity has been studied in the framework of holography. we find that there is a first order phase transition ( fpt ) and second order phase transition ( spt ) both in bekenstein - hawking entropy ( bhe ) - temperature plane and holographic entanglement entropy ( hee ) - temperature plane. furthermore, for the fpt, the equal area law is checked and for the spt, the critical exponent of the heat capacity is also computed. our results confirm that the phase structure of hee is similar to that of bhe in lorentz breaking massive gravity, which implies that hee and bhe have some potential underlying relationship.
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arxiv:1706.04431
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this pictorial aims to critically consider the nature of text - to - audio and text - to - music generative tools in the context of explainable ai. as a group of experimental musicians and researchers, we are enthusiastic about the creative potential of these tools and have sought to understand and evaluate them from perspectives of prompt creation, control, usability, understandability, explainability of the ai process, and overall aesthetic effectiveness of the results. one of the challenges we have identified that is not explicitly addressed by these tools is the inherent semantic gap in using text - based tools to describe something as abstract as music. other gaps include explainability vs. useability, and user control and input vs. the human creative process. the aim of this pictorial is to raise questions for discussion and make a few general suggestions on the kinds of improvements we would like to see in generative ai music tools.
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arxiv:2408.07224
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exact analytical calculations are performed to study the rotating magnetoelectric effect in a ground state of a coupled spin - electron model on a doubly decorated square lattice with and without presence of an external magnetic field. novel spatially anisotropic magnetic ground states emergent due to a rotation in an external electric field are found at three physically interesting electron concentrations ranging from a quarter up to a half filling. in absence of the magnetic field existence of spatially anisotropic structures requires a fractional electron concentration, where a significant influence of spatial orientation of an electric field is observed. it turns out that the investigated model exhibits a rotating magnetoelectric effect at all three concentrations with one or two consecutive critical points in presence of magnetic field. at the same time, the rotating electric field has a significant effect on a critical value of an electrostatic potential, which can be enhanced or lowered upon changing the electron hopping and the magnitude of an applied magnetic field. finally, we have found an intriguing interchange of magnetic order between the horizontal and vertical directions driven by a rotation of the electric field, which is however destabilized upon strengthening of the magnetic field.
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arxiv:2311.17495
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the observation of the kondo effect in quantum dots has provided new opportunities to finally observe the controversial kondo screening cloud. we study how screening cloud effects appear in the conductance through a quantum wire containing a quantum dot when the length of the wire is comparable to the size of the screening cloud.
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arxiv:cond-mat/0204062
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inspired from electronic systems, topological photonics aims to engineer new optical devices with robust properties. in many cases, the ideas from topological phases protected by internal symmetries in fermionic systems are extended to those protected by crystalline symmetries. one such popular photonic crystal model was proposed by wu and hu in 2015 for realizing a bosonic $ \ mathbb { z } _ 2 $ topological crystalline insulator with robust topological edge states, which led to intense theoretical and experimental studies. however, rigorous relationship between the bulk topology and edge properties for this model, which is central to evaluating its advantage over traditional photonic designs, has never been established. in this work we revisit the expanded and shrunken honeycomb lattice structures proposed by wu and hu by using topological quantum chemistry tools and show that they are topologically trivial in the sense that symmetric, localized wannier functions can be constructed. we show that the $ \ mathbb { z } $ and $ \ mathbb { z } _ 2 $ type classification of the wu - hu model are equivalent to the $ c _ 2t $ protected euler class and the second stiefel - whitney class respectively, with the latter characterizing the full valence bands of wu - hu model indicating only a higher order topological insulator ( hoti ) phase. we show that the wu - hu interface states can be gapped by a uniform topology preserving $ c _ 6 $ and $ t $ symmetric perturbation, which demonstrates the trivial nature of the interface. our results reveals that topology is not a necessary condition for the reported helical edge states in many photonics systems and opens new possibilities for interface engineering that may not be constrained to require topological designs.
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arxiv:2303.12617
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following a previous work on abelian ( 2, 0 ) - gauge theories, one reassesses here the task of coupling ( 2, 0 ) relaxed yang - mills super - potentials to a ( 2, 0 ) - nonlinear sigma - model, by gauging the isotropy or the isometry group of the latter. one pays special attention to the extra " chiral - like " component - field gauge potential that comes out from the relaxation of constraints.
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arxiv:hep-th/0006065
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new estimates of the potentials of solutions to the compressible navier - stokes equations are derived. the result obtained are applied to boundary value problems for the compressible navier - stokes equations with the critical adiabatic exponents. the cancelation of concentrations of the kinetic energy density is proved
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arxiv:2212.07031
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in recent years, unsupervised domain adaptation ( uda ) has gained significant attention in the field of natural language processing ( nlp ) owing to its ability to enhance model generalization across diverse domains. however, its application for knowledge transfer between distinct legal domains remains largely unexplored. to address the challenges posed by lengthy and complex legal texts and the limited availability of large - scale annotated datasets, we propose jurisctc, a novel model designed to improve the accuracy of legal judgment prediction ( ljp ) tasks. unlike existing approaches, jurisctc facilitates effective knowledge transfer across various legal domains and employs contrastive learning to distinguish samples from different domains. specifically, for the ljp task, we enable knowledge transfer between civil and criminal law domains. compared to other models and specific large language models ( llms ), jurisctc demonstrates notable advancements, achieving peak accuracies of 76. 59 % and 78. 83 %, respectively.
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arxiv:2504.17264
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we show that the use of 1, 3 - diaminopropane ( dap ) as a chemical modifier at the perovskite / electron - transport layer ( etl ) interface enhances the power conversion efficiency ( pce ) of 1. 7 ev bandgap facs mixed - halide perovskite single - junction cells, primarily by boosting the open - circuit voltage ( voc ) from 1. 06 v to 1. 15 v. adding a post - processing annealing step after c60 evaporation, further improves the fill factor ( ff ) by 20 % from the control to the dap + post - annealing devices. using hyperspectral photoluminescence microscopy, we demonstrate that annealing helps improve compositional homogeneity at the top and bottom interfaces of the solar cell, which prevents detrimental bandgap pinning in the devices and improves c60 adhesion. using time - of - flight secondary ion mass spectrometry, we show that dap reacts with formamidinium present near the surface of the perovskite lattice to form a larger molecular cation, 1, 4, 5, 6 - tetrahydropyrimidinium ( thp ) that remains at the interface. combining the use of dap and the annealing of c60 interface, we fabricate si - perovskite tandems with pce of 25. 29 %, compared to 23. 26 % for control devices. our study underscores the critical role of chemical reactivity and thermal post - processing of the c60 / lewis - base passivator interface in minimizing device losses and advancing solar - cell performance of wide - bandgap mixed - cation mixed - halide perovskite for tandem application.
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arxiv:2411.18756
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single - particle electron cryomicroscopy is an essential tool for high - resolution 3d reconstruction of proteins and other biological macromolecules. an important challenge in cryo - em is the reconstruction of non - rigid molecules with parts that move and deform. traditional reconstruction methods fail in these cases, resulting in smeared reconstructions of the moving parts. this poses a major obstacle for structural biologists, who need high - resolution reconstructions of entire macromolecules, moving parts included. to address this challenge, we present a new method for the reconstruction of macromolecules exhibiting continuous heterogeneity. the proposed method uses projection images from multiple viewing directions to construct a graph laplacian through which the manifold of three - dimensional conformations is analyzed. the 3d molecular structures are then expanded in a basis of laplacian eigenvectors, using a novel generalized tomographic reconstruction algorithm to compute the expansion coefficients. these coefficients, which we name spectral volumes, provide a high - resolution visualization of the molecular dynamics. we provide a theoretical analysis and evaluate the method empirically on several simulated data sets.
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arxiv:1907.01898
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photonic skyrmion and meron lattices are structured light fields with topologically protected textures, analogous to magnetic skyrmions and merons. here, we report the theoretical existence of mixed skyrmion and meron quasicrystals in an evanescent optical field. topological quasiperiodic tilings of even and odd point group symmetries are demonstrated in both the electric field and spin angular momentum. these quasicrystals contain both skyrmions and merons of n \ ' eel - type topology. interestingly, the quasiperiodic tilings are in agreement with the observations of quasiperiodic arrangements of carbon nanoparticles in water driven by ultrasound, and pave the way towards engineering hybrid topological states of light which may have potential applications in optical manipulation, metrology and information processing.
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arxiv:2409.03932
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clip ( contrastive language - image pre - training ) has attained great success in pattern recognition and computer vision. transferring clip to downstream tasks ( e. g. zero - or few - shot classification ) is a hot topic in multimodal learning. however, current studies primarily focus on either prompt learning for text or adapter tuning for vision, without fully exploiting the complementary information and correlations among image - text pairs. in this paper, we propose an image description enhanced clip - adapter ( idea ) method to adapt clip to few - shot image classification tasks. this method captures fine - grained features by leveraging both visual features and textual descriptions of images. idea is a training - free method for clip, and it can be comparable to or even exceeds state - of - the - art models on multiple tasks. furthermore, we introduce trainable - idea ( t - idea ), which extends idea by adding two lightweight learnable components ( i. e., a projector and a learnable latent space ), further enhancing the model ' s performance and achieving sota results on 11 datasets. as one important contribution, we employ the llama model and design a comprehensive pipeline to generate textual descriptions for images of 11 datasets, resulting in a total of 1, 637, 795 image - text pairs, named " imd - 11 ". our code and data are released at https : / / github. com / fourierai / idea.
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arxiv:2501.08816
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gravitational waves emitted by asymmetric rotating neutron stars are the primary targets of continuous gravitational - wave searches. neutron stars in binary systems are particularly interesting due to the potential for non - axisymmetric deformations induced by a companion star. however, all - sky searches for unknown neutron stars in binary systems are very computationally expensive and this limits their sensitivity and / or breadth. in this paper we present results of a search for signals with gravitational - wave frequencies between $ 50 $ and $ 150 $ ~ hz, from systems with orbital periods between $ 100 $ and $ 1 \, 000 $ days and projected semi - major axes between $ 40 $ and $ 200 $ ~ light - seconds. this parameter - space region has never been directly searched before. we do not detect any signal, and our results exclude gravitational - wave amplitudes above $ 1. 25 \ times 10 ^ { - 25 } $ at $ 144. 32 $ ~ hz with $ 95 \ % $ confidence. our improved search pipeline is more sensitive than any previous all - sky binary search by about $ 75 \ % $.
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arxiv:2409.16196
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