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deep learning ( dl ) algorithms have become the { \ em de facto } choice for data analysis. several dl implementations - - primarily limited to a single compute node - - such as caffe, tensorflow, theano and torch have become readily available. distributed dl implementations capable of execution on large scale systems are becoming important to address the computational needs of large data produced by scientific simulations and experiments. yet, the adoption of distributed dl implementations faces significant impediments : 1 ) most implementations require dl analysts to modify their code significantly - - which is a show - stopper, 2 ) several distributed dl implementations are geared towards cloud computing systems - - which is inadequate for execution on massively parallel systems such as supercomputers. this work addresses each of these problems. we provide a distributed memory dl implementation by incorporating required changes in the tensorflow runtime itself. this dramatically reduces the entry barrier for using a distributed tensorflow implementation. we use message passing interface ( mpi ) - - which provides performance portability, especially since mpi specific changes are abstracted from users. lastly - - and arguably most importantly - - we make our implementation available for broader use, under the umbrella of machine learning toolkit for extreme scale ( matex ) at { \ texttt http : / / hpc. pnl. gov / matex }. we refer to our implementation as matex - tensorflow.
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arxiv:1704.04560
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we present a novel method, contextual goal - oriented data augmentation ( coda ), which uses commonly available unlabeled trajectories and context - goal pairs to solve contextual goal - oriented ( cgo ) problems. by carefully constructing an action - augmented mdp that is equivalent to the original mdp, coda creates a fully labeled transition dataset under training contexts without additional approximation error. we conduct a novel theoretical analysis to demonstrate coda ' s capability to solve cgo problems in the offline data setup. empirical results also showcase the effectiveness of coda, which outperforms other baseline methods across various context - goal relationships of cgo problem. this approach offers a promising direction to solving cgo problems using offline datasets.
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arxiv:2408.07753
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we propose a graded classification of the entire field of multivector physics, including all alternative points of view. the ( often tacit ) postulates of different types of formulations are contrasted, summarizing their consequences. specifically, spin - gauge formulations of gravitation and gut which assume standard column spinors will require unnecessarily large matrix algebras. an extreme generalization is introduced, where wavefunctions are multivectors, in which multiple generations of particles naturally appear without resorting to increasing the size of the algebra. further, this allows for two - sided ( bilateral ) operators, which can accomodate in excess of 10 times more gauge fields without increasing the algebraic representation. as this generalization encompasses all the essential features of the other categories, it is proposed to be the best path to new physics. [ summary of talk at 3rd international conf on clifford algebras and their appl. in physics, deinze, belgium may 1993 ].
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arxiv:gr-qc/9306006
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the discovery of superconductivity with a critical temperature exceeding 55 k in the iron - oxypnictides and related compounds has quite suddenly given the community a new set of materials - breaking the tyranny of copper. this new class of materials raises fundamental questions related to the origin of the electron pairing in the superconducting state and to the similarity to superconductivity in the cuprates. here, we report spatially resolved measurements using scanning tunneling microscopy / spectroscopy ( stm / sts ) of the newly discovered iron - based layered superconductor ndfeaso0. 86f0. 14 ( tc = 48 k ) as a function of temperature. the tunneling spectra at 17 k show a suppression of spectral intensity within + / - 10 mev, indicative of the opening of the superconducting gap ( sg ). below tc, the sample exhibits two characteristic gaps - a large one ( 18 mev ) and a small one ( 9 mev ) - existing in different spatial locations. both gaps are closed above tc at the bulk tc, but only the small gap can be fitted with a superconducting gap function. this gap displays a bcs - like order parameter. above tc, at the same location where the small gap was observed, a pseudogap ( pg ) opens abruptly at a temperature just above tc and closes at 120 k. in contrast to the cuprates, the sg and pg have competing order parameters.
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arxiv:0808.0895
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^ { d - 2i } $ and $ \ theta ^ * _ i = a ^ * + b ^ * q ^ { 2i - d } + c ^ * q ^ { d - 2i } $ for $ 0 \ leq i \ leq d $, where $ q, a, b, c, a ^ *, b ^ *, c ^ * $ are scalars in $ k $ with $ q, b, c, b ^ *, c ^ * $ nonzero and $ q ^ 2 \ not \ in \ lbrace 1, - 1 \ rbrace $. this type is the most general one. we classify up to isomorphism the tridiagonal pairs over $ k $ that have $ q $ - racah type. our proof involves the representation theory of the quantum affine algebra $ u _ q ( \ widehat { \ mathfrak { sl } } _ 2 ) $.
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arxiv:0807.0271
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although organic heterojunctions can separate charges with near - unity efficiency and on a sub - picosecond timescale, the full details of the charge - separation process remain unclear. in typical models, the coulomb binding between the electron and the hole can exceed the thermal energy $ k _ \ mathrm { b } t $ by an order of magnitude, suggesting that it is impossible for the charges to separate before recombining. here, we consider the entropic contribution to charge separation in the presence of disorder and find that even modest amounts of disorder have a decisive effect, reducing the charge - separation barrier to about $ k _ \ mathrm { b } t $ or eliminating it altogether. therefore, the charges are usually not thermodynamically bound at all and could separate spontaneously if the kinetics otherwise allowed it. our conclusion holds despite the worst - case assumption of localised, thermalised carriers, and is only strengthened if mechanisms like delocalisation or ` hot ' states are also present.
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arxiv:1603.06304
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we investigate geometrical properties and inequalities satisfied by the complex difference body, in the sense of studying which of the classical ones for the difference body have an analog in the complex framework. among others we give an equivalent expression for the support function of the complex difference body and prove that, unlike the classical case, the dimension of the complex difference body depends on the position of the body with respect to the complex structure of the vector space. we use spherical harmonics to characterize the bodies for which the complex difference body is a ball, we prove that it is a polytope if and only if the two bodies involved in the construction are polytopes and provide several inequalities for classical magnitudes of the complex difference body, as volume, quermassintegrals and diameter, in terms of the corresponding ones for the involved bodies.
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arxiv:1602.00960
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aims. we investigate the stability of non - isothermal bonnor - ebert spheres with a model that includes a self - consistent calculation of the gas temperature. this way we can discard the assumption of equality between the dust and gas temperatures, and study the stability as the gas temperature changes with chemical evolution of the gas. methods. we use a gas - grain chemical model including a time - dependent treatment of depletion onto grain surfaces, which strongly influences the gas temperature as the main coolant, co, depletes from the gas. dust and gas temperatures are solved with radiative transfer. for comparison with previous work, we assume that the cores are deeply embedded in a larger external structure, corresponding to visual extinction $ a _ { \ rm v } ^ { \ rm ext } = 10 $ mag. results. we find that the critical non - dimensional radius $ \ xi _ 1 $ derived here is similar to our previous work where we assumed $ t _ { \ rm dust } = t _ { \ rm gas } $ ; the $ \ xi _ 1 $ values lie below the isothermal critical value $ \ xi _ 0 \ sim6. 45 $, but the difference is less than 10 %. chemical evolution does not affect notably the stability condition of low - mass cores ( < 0. 75 $ m _ \ odot $ ). for higher masses the decrease of cooling owing to co depletion causes substantial temporal changes in the temperature and density profiles of the cores. in the mass range 1 - 2 $ m _ \ odot $, $ \ xi _ 1 $ decreases with chemical evolution, whereas above 3 $ m _ \ odot $, $ \ xi _ 1 $ instead increases. we also find that decreasing $ a _ { \ rm v } ^ { \ rm ext } $ increases the gas temperature especially when the gas is chemically old, causing $ \ xi _ 1 $ to increase with respect to models with higher $ a _ { \ rm v } ^ { \ rm ext } $. the derived $ \ xi _ 1 $ values are close to $ \ xi _ 0 $. the density contrast between the core center and edge varies between 8 to 16 depending on core mass and the chemical age of the gas, compared to the constant value $ \ sim $ 14. 1 for the isothermal bes.
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arxiv:1508.06151
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diophantine problems involving recurrence sequences have a long history and is an actively studied topic within number theory. in this paper, we connect to the field by considering the equation \ begin { align * } b _ mb _ { m + d } \ dots b _ { m + ( k - 1 ) d } = y ^ \ ell \ end { align * } in positive integers $ m, d, k, y $ with $ \ gcd ( m, d ) = 1 $ and $ k \ geq 2 $, where $ \ ell \ geq 2 $ is a fixed integer and $ b = ( b _ n ) _ { n = 1 } ^ \ infty $ is an elliptic divisibility sequence, an important class of non - linear recurrences. we prove that the above equation admits only finitely many solutions. in fact, we present an algorithm to find all possible solutions, provided that the set of $ \ ell $ - th powers in $ b $ is given. ( note that this set is known to be finite. ) we illustrate our method by an example.
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arxiv:1604.03707
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in this paper we examine the detailed theory of the american football in flight, with spin and air resistance included. we find the theory has much in common with the theory of a gyroscope and also rocket trajectory with a misaligned thruster. unfortunately most of the air resistance data, for rocketry and ballistics, is for speeds of mach 1 or higher, where the air resistance increases dramatically. we shall approximate a realistic air resistance, at the slower speeds of football flight, with a drag force proportional to cross sectional area and either $ v $ or $ v ^ 2 $, depending on speed, where $ v $ is velocity of the football. we begin with a discussion of the motion, giving as much detail as possible without the use of complex analytic calculations. we point out the previous errors made with moments of inertia and make the necessary corrections for more accurate results. we show that the shape of an american football closely resembles a parabola of revolution.
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arxiv:0706.0366
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in this article, families of non - linear subdivision schemes are presented that are based on univariate polynomials up to degree three. theses families of schemes are constructed by using dynamic iterative re - weighed least squares method. these schemes are suitable for fitting scattered data with noise and outliers. although these schemes are non - interpolatory, but have the ability to preserve the shape of the initial polygon in case of non - noisy initial data. the numerical examples illustrate that the schemes constructed by non - linear polynomials give better performance than the schemes that are constructed by linear polynomials ( computer - aided design, 58, 189 - 199 ). moreover, the numerical examples show that these schemes have the ability to reproduce polynomials and do not cause over and under fitting of the data. furthermore, families of non - linear bivariate subdivision schemes are also presented that are based on linear and non - linear bivariate polynomials.
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arxiv:1709.04282
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continual event detection ( ced ) poses a formidable challenge due to the catastrophic forgetting phenomenon, where learning new tasks ( with new coming event types ) hampers performance on previous ones. in this paper, we introduce a novel approach, lifelong event detection via optimal transport ( ledot ), that leverages optimal transport principles to align the optimization of our classification module with the intrinsic nature of each class, as defined by their pre - trained language modeling. our method integrates replay sets, prototype latent representations, and an innovative optimal transport component. extensive experiments on maven and ace datasets demonstrate ledot ' s superior performance, consistently outperforming state - of - the - art baselines. the results underscore ledot as a pioneering solution in continual event detection, offering a more effective and nuanced approach to addressing catastrophic forgetting in evolving environments.
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arxiv:2410.08905
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a quantum error - correcting code is defined to be a unitary mapping ( encoding ) of k qubits ( 2 - state quantum systems ) into a subspace of the quantum state space of n qubits such that if any t of the qubits undergo arbitrary decoherence, not necessarily independently, the resulting n qubits can be used to faithfully reconstruct the original quantum state of the k encoded qubits. quantum error - correcting codes are shown to exist with asymptotic rate k / n = 1 - 2h ( 2t / n ) where h ( p ) is the binary entropy function - p log p - ( 1 - p ) log ( 1 - p ). upper bounds on this asymptotic rate are given.
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arxiv:quant-ph/9512032
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high - throughput sequencing of b - and t - cell receptors makes it possible to track immune repertoires across time, in different tissues, and in acute and chronic diseases or in healthy individuals. however, quantitative comparison between repertoires is confounded by variability in the read count of each receptor clonotype due to sampling, library preparation, and expression noise. here, we present a general bayesian approach to disentangle repertoire variations from these stochastic effects. using replicate experiments, we first show how to learn the natural variability of read counts by inferring the distributions of clone sizes as well as an explicit noise model relating true frequencies of clones to their read count. we then use that null model as a baseline to infer a model of clonal expansion from two repertoire time points taken before and after an immune challenge. applying our approach to yellow fever vaccination as a model of acute infection in humans, we identify candidate clones participating in the response.
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arxiv:1912.08304
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the cosmic web structure is studied with the concepts and methods of fractal geometry, employing the adhesion model of cosmological dynamics as a basic reference. the structures of matter clusters and cosmic voids in cosmological n - body simulations or the sloan digital sky survey are elucidated by means of multifractal geometry. a non - lacunar multifractal geometry can encompass three fundamental descriptions of the cosmic structure, namely, the web structure, hierarchical clustering, and halo distributions. furthermore, it explains our present knowledge of cosmic voids. in this way, a unified theory of the large - scale structure of the universe seems to emerge. the multifractal spectrum that we obtain significantly differs from the one of the adhesion model and conforms better to the laws of gravity. the formation of the cosmic web is best modeled as a type of turbulent dynamics, generalizing the known methods of burgers turbulence.
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arxiv:1810.02311
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we study the relation between the microscopic properties of a many - body system and the electron spectra, experimentally accessible by photoemission. in a recent paper [ phys. rev. lett. 114, 236402 ( 2015 ) ], we introduced the " fluctuation diagnostics " approach, to extract the dominant wave vector dependent bosonic fluctuations from the electronic self - energy. here, we first reformulate the theory in terms of fermionic modes, to render its connection with resonance valence bond ( rvb ) fluctuations more transparent. secondly, by using a large - u expansion, where u is the coulomb interaction, we relate the fluctuations to real space correlations. therefore, it becomes possible to study how electron spectra are related to charge, spin, superconductivity and rvb - like real space correlations, broadening the analysis of an earlier work [ phys. rev. b 89, 245130 ( 2014 ) ]. this formalism is applied to the pseudogap physics of the two - dimensional hubbard model, studied in the dynamical cluster approximation. we perform calculations for embedded clusters with up to 32 sites, having three inequivalent k - points at the fermi surface. we find that as u is increased, correlation functions gradually attain values consistent with an rvb state. this first happens for correlation functions involving the antinodal point and gradually spreads to the nodal point along the fermi surface. simultaneously a pseudogap opens up along the fermi surface. we relate this to a crossover from a kondo - like state to an rvb - like localized cluster state and to the presence of rvb and spin fluctuations. these changes are caused by a strong momentum dependence in the cluster bath - couplings along the fermi surface. we also show, from a more algorithmic perspective, how the time - consuming calculations in fluctuation diagnostics can be drastically simplified.
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arxiv:1711.07671
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light - induced instabilities / degradation in cu ( in, ga ) se2 ( cigs ) solar cells are a prevalent and urgent issue to resolve to improve performance, uniformity, and reliability. here, mechanisms contributing to light - induced instabilities are identified focusing on an observed short circuit current ( jsc ) reduction. external quantum efficiency measurements before and after light soaking identified a reduction in long wavelength photon carrier collection efficiency in the cigs absorber layer. using deep level optical spectroscopy ( dlos ), the concentration of cigs ev + 0. 98 ev deep level is correlated with the amount of jsc degradation, finally, capacitance voltage ( c - v ) measurements reveal light induces a large reduction in the depletion depth and reduction of carrier collection and are all correlated with the jsc reduction. finally, the ev + 0. 53 ev trap concentrations are shown to correlate with voc instability but not the jsc reduction confirming that multiple trap - induced mechanism are responsible for the light - induced instabilities.
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arxiv:1806.06665
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given a family of continuous real functions $ \ mathcal { g } $, let $ r _ \ mathcal { g } $ be a binary relation defined as follows : a continuous function $ f \ colon \ mathbb { r } \ to \ mathbb { r } $ is in the relation with a closed set $ e \ subseteq \ mathbb { r } $ if and only if there exists $ g \ in \ mathcal { g } $ such that $ f \ upharpoonright e = g \ upharpoonright e $. we consider a galois connection between families of continuous functions and hereditary families of closed sets of reals naturally associated to $ r _ \ mathcal { g } $. we study complete lattices determined by this connection and prove several results showing the dependence of the properties of these lattices on the properties of $ \ mathcal { g } $. in some special cases we obtain exact description of these lattices.
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arxiv:1810.01100
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in the present paper, motivated by a conjecture of jahan and zheng, we prove that componentwise polymatroidal ideals have linear quotients. this solves positively a conjecture of bandari and herzog.
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arxiv:2312.13006
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we analyze the stability of a nonlinear dynamical model describing the noncooperative strategic interactions among the agents of a finite collection of populations. each agent selects one strategy at a time and revises it repeatedly according to a protocol that typically prioritizes strategies whose payoffs are either higher than that of the current strategy or exceed the population average. the model is predicated on well - established research in population and evolutionary games, and has two sub - components. the first is the payoff dynamics model ( pdm ), which ascribes the payoff to each strategy according to the proportions of every population adopting the available strategies. the second sub - component is the evolutionary dynamics model ( edm ) that accounts for the revision process. in our model, the social state at equilibrium is a best response to the payoff, and can be viewed as a nash - like solution that has predictive value when it is globally asymptotically stable ( gas ). we present a systematic methodology that ascertains gas by checking separately whether the edm and pdm satisfy appropriately defined system - theoretic dissipativity properties. our work generalizes pioneering methods based on notions of contractivity applicable to memoryless pdms, and more general system - theoretic passivity conditions. as demonstrated with examples, the added flexibility afforded by our approach is particularly useful when the contraction properties of the pdm are unequal across populations.
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arxiv:2005.03797
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we report a measurement of a new high spin jp = 5 - state at 22. 4 ( 0. 2 ) mev in 12c which fits very well to the predicted ( ground state ) rotational band of an oblate equilateral triangular spinning top with a d _ 3h symmetry characterized by the sequence 0 +, 2 +, 3 -, 4 + / -, 5 - with almost degenerate 4 + and 4 - ( parity doublet ) states. such a d _ 3h symmetry was observed in triatomic molecules and it is observed here for the first time in nuclear physics. we discuss a classification of other rotation - vibration bands in 12c such as the ( 0 + ) hoyle band and the ( 1 - ) bending mode band and suggest measurements in search of the predicted ( " missing " ) states that may shed new light on clustering in 12c and light nuclei. in particular the observation ( or non - observation ) of the predicted ( " missing " ) states in the hoyle band will allow us to conclude the geometrical arrangement of the three alpha - particle composing the hoyle state at 7. 654 mev in 12c.
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arxiv:1405.7445
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we study the use of linear regression for multiclass classification in the over - parametrized regime where some of the training data is mislabeled. in such scenarios it is necessary to add an explicit regularization term, $ \ lambda f ( w ) $, for some convex function $ f ( \ cdot ) $, to avoid overfitting the mislabeled data. in our analysis, we assume that the data is sampled from a gaussian mixture model with equal class sizes, and that a proportion $ c $ of the training labels is corrupted for each class. under these assumptions, we prove that the best classification performance is achieved when $ f ( \ cdot ) = \ | \ cdot \ | ^ 2 _ 2 $ and $ \ lambda \ to \ infty $. we then proceed to analyze the classification errors for $ f ( \ cdot ) = \ | \ cdot \ | _ 1 $ and $ f ( \ cdot ) = \ | \ cdot \ | _ \ infty $ in the large $ \ lambda $ regime and notice that it is often possible to find sparse and one - bit solutions, respectively, that perform almost as well as the one corresponding to $ f ( \ cdot ) = \ | \ cdot \ | _ 2 ^ 2 $.
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arxiv:2402.10474
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this paper is devoted to the uniqueness problem of the power of a meromorphic function with its differential polynomial sharing a set. our result will extend a number of results obtained in the theory of normal families. some questions are posed for future research.
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arxiv:1702.02037
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we calculate the o ( g ^ 2 a ) mixing coefficients of bilinear quark operators in lattice qcd using a standard perturbative evaluation of on - shell green ' s functions. our results for the plaquette gluon action are in agreement with those previously obtained with the schr \ " odinger functional method. the coefficients are also calculated for a class of improved gluon actions having six - link terms.
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arxiv:hep-lat/9806015
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we classify the 3 - dimensional hyperbolic polyhedral orbifolds that contain no embedded essential 2 - suborbifolds, up to decomposition along embedded hyperbolic triangle orbifolds ( turnovers ). we give a necessary condition for a 3 - dimensional hyperbolic polyhedral orbifold to contain an immersed ( singular ) hyperbolic turnover, we classify the triangle subgroups of the fundamental groups of orientable 3 - dimensional hyperbolic tetrahedral orbifolds in the case when all of the vertices of the tetrahedra are non - finite, and we provide a conjectural classification of all the triangle subgroups of the fundamental groups of orientable 3 - dimensional hyperbolic polyhedral orbifolds. finally, we show that any triangle subgroup of a ( non - orientable ) 3 - dimensional hyperbolic reflection group arises from a triangle reflection subgroup.
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arxiv:1102.0322
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measured hard photon multiplicities from second - chance nucleon - nucleon collisions are used in combination with a kinetic thermal model, to estimate the break - up times of excited nuclear systems produced in nucleus - nucleus reactions at intermediate energies. the obtained nuclear break - up time for the $ ^ { 129 } $ { xe } + $ ^ { nat } $ { sn } reaction at 50 { \ it a } mev is $ \ delta $ $ \ tau $ $ \ approx $ 100 - - 300 fm / $ c $ for all reaction centralities. the lifetime of the radiating sources produced in seven other different heavy - ion reactions studied by the taps experiment are consistent with $ \ delta $ $ \ tau $ $ \ approx $ 100 fm / $ c $, such relatively long thermal photon emission times do not support the interpretation of nuclear breakup as due to a fast spinodal process for the heavy nuclear systems studied.
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arxiv:nucl-ex/0508032
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the kinematics of 150 carbon stars observed at moderate dispersion on the periphery of the small magellanic cloud are compared with the motions of neutral hydrogen and early type stars in the inter - cloud region. the distribution of radial velocities implies a configuration of these stars as a sheet inclined at 73 + / - 4 degrees to the plane of the sky. the near side, to the south, is dominated by a stellar component ; to the north, the far side contains fewer carbon stars, and is dominated by the neutral gas. the upper velocity envelope of the stars is closely the same as that of the gas. this configuration is shown to be consistent with the known extension of the smc along the line of sight, and is attributed to a tidally induced disruption of the smc that originated in a close encounter with the lmc some 0. 3 to 0. 4 gyr ago. the dearth of gas on the near side of the sheet is attributed to ablation processes akin to those inferred by weiner & williams ( 1996 ) to collisional excitation of the leading edges of magellanic stream clouds. comparison with pre lmc / smc encounter kinematic data of hardy, suntzeff, & azzopardi ( 1989 ) of carbon stars, with data of stars formed after the encounter, of maurice et al. ( 1989 ), and mathewson et al. ( a986, 1988 ) leaves little doubt that forces other than gravity play a role in the dynamics of the h i.
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arxiv:astro-ph/0003395
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we develop new high - order results for the post - newtonian ( pn ) expansions of the energy and angular momentum fluxes at infinity for eccentric - orbit extreme - mass - ratio inspirals ( emris ) on a schwarzschild background. the series are derived through direct expansion of the mst solutions within the rwz formalism for first - order black hole perturbation theory ( bhpt ). by utilizing factorization and a few computational simplifications, we are able to compute the fluxes to 19pn, with each pn term calculated as a power series in ( darwin ) eccentricity to $ e ^ { 10 } $. this compares favorably with the numeric fitting approach used in previous work. we also compute pn terms to $ e ^ { 20 } $ through 10pn. then, we analyze the convergence properties of the composite energy flux expansion by checking against numeric data for several orbits, both for the full flux and also for the individual 220 mode, with various resummation schemes tried for each. the match between the high - order series and numerical calculations is generally strong, maintaining relative error better than $ 10 ^ { - 5 } $ except when $ p $ ( the semi - latus rectum ) is small and $ e $ is large. however, the full - flux expansion demonstrates superior fidelity ( particularly at high $ e $ ), as it is able to incorporate additional information from pn theory. for the orbit $ ( p = 10, e = 1 / 2 ) $, the full flux achieves a best error near $ 10 ^ { - 5 } $, while the 220 mode exhibits error worse than $ 1 \ % $. finally, we describe a procedure for transforming these expansions to the harmonic gauge of pn theory by analyzing schwarzschild geodesic motion in harmonic coordinates. this will facilitate future comparisons between bhpt and pn theory.
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arxiv:2008.10622
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we report the statistical properties of stars, brown dwarfs and multiple systems obtained from the largest radiation hydrodynamical simulation of star cluster formation to date that resolves masses down to the opacity limit for fragmentation ( a few jupiter masses ). the initial conditions are identical to those of previous barotropic calculations published by bate, but this time the calculation is performed using a realistic equation of state and radiation hydrodynamics. the calculation uses sink particles to model 183 stars and brown dwarfs, including 28 binaries and 12 higher - order multiple systems, the properties of which are compared the results from observational surveys. we find that the radiation hydrodynamical / sink particle simulation reproduces many observed stellar properties very well. in particular, whereas using a barotropic equation of state produces more brown dwarfs than stars, the inclusion of radiative feedback results in a stellar mass function and a ratio of brown dwarfs to stars in good agreement with observations of galactic star - forming regions. in addition, many of the other statistical properties of the stars and brown dwarfs are in reasonable agreement with observations, including multiplicity as a function of primary mass, the frequency of very - low - mass binaries, and general trends for the mass ratio and separation distributions of binaries. we also examine the velocity dispersion of the stars, the distributions of disc truncation radii due to dynamical interactions, and coplanarity of orbits and sink particle spins in multiple systems. overall, the calculation produces a cluster of stars whose statistical properties are difficult to distinguish from observed systems, implying that gravity, hydrodynamics, and radiative feedback are the primary ingredients for determining the origin of the statistical properties of low - mass stars.
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arxiv:1110.1092
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the microlocal space - time of extended hadrons, considered to be anisotropic is specified here as a special finsler space. for this space the classical field equation is obtained from a property of the field on the neighbouring points of the autoparallel curve. the quantum field equation has also been derived for the bispinor field of a free lepton in this finslerian microspace through its quantum generalization below a fundamental length - scale. the bispinor can be decomposed as a direct product of two spinsors, one depending on the position coordinates and the other on the directional arguments of the finsler space. the former one represents the spinor of the macrospace, an associated riemannian space - time of the finsler space, and satisfies the dirac equation. the directional variable - dependent spinor satisfies a different equation which is solved here. this spinor - part of the bispinor field for a constituent of the hadron can give rise to an additional quantum number for generating the internal symmetry of hadrons. also, it is seen that in the process of separating the bispinor field and its equation an epoch - dependent mass term arises. although, this part of the particle - mass has no appreciable contribution in the present era it was very significant for the very early period of the universe after its creation. finally, the field equations for a particle in an external electromagnetic field for this finslerian microlocal space - time and its associated riemannian macrospaces have been found.
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arxiv:hep-th/0308180
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in a liquid of superconducting vortices, a longitudinal thermal gradient generates a transverse electric field. this nernst signal peaks at an intermediate temperature and magnetic field, presumably where the entropy difference between the vortex core and the superfluid environment is largest. there is a puzzling similarity of the amplitude of this peak across many different superconductors. this peak can be assimilated to a minimum in the viscosity to entropy density ratio of the vortex liquid. expressed in units of $ \ frac { \ hbar } { k _ b } $, this minimum is one order of magnitude larger than what is seen in common liquids. moreover, the entropy stocked in the vortex core is \ textit { not } identical to the entropy bound to a moving magnetic flux line. due to a steady exchange of normal quasi - particles, entropy can leak from the vortex core. a slowly moving vortex will be peeled off its entropy within a distance of the order of a superconducting coherence length, provided that the $ \ frac { \ delta } { e _ f } $ ratio is sufficiently large.
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arxiv:2212.09480
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we provide necessary and sufficient conditions on the derived type of a vector field distribution $ \ cal v $ in order that it be locally equivalent to a partial prolongation of the contact distribution $ \ cal c ^ { ( 1 ) } _ q $, on the first order jet bundle of maps from $ \ bbb r $ to $ \ bbb r ^ q $, $ q \ geq 1 $. this result fully generalises the classical goursat normal form. our proof is constructive : it is proven that if $ \ cal v $ is locally equivalent to a partial prolongation of $ \ cal c ^ { ( 1 ) } _ q $ then the explicit construction of contact coordinates algorithmically depends upon the integration of a sequence of geometrically defined and algorithmically determined integrable pfaffian systems on the ambient manifold.
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arxiv:math/0404377
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a model - agnostic variable importance method can be used with arbitrary prediction functions. here we present some model - free methods that do not require access to the prediction function. this is useful when that function is proprietary and not available, or just extremely expensive. it is also useful when studying residuals from a model. the cohort shapley ( cs ) method is model - free but has exponential cost in the dimension of the input space. a supervised on - manifold shapley method from frye et al. ( 2020 ) is also model free but requires as input a second black box model that has to be trained for the shapley value problem. we introduce an integrated gradient ( ig ) version of cohort shapley, called igcs, with cost $ \ mathcal { o } ( nd ) $. we show that over the vast majority of the relevant unit cube that the igcs value function is close to a multilinear function for which igcs matches cs. another benefit of igcs is that is allows ig methods to be used with binary predictors. we use some area between curves ( abc ) measures to quantify the performance of igcs. on a problem from high energy physics we verify that igcs has nearly the same abcs as cs does. we also use it on a problem from computational chemistry in 1024 variables. we see there that igcs attains much higher abcs than we get from monte carlo sampling. the code is publicly available at https : / / github. com / cohortshapley / cohortintgrad
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arxiv:2211.08414
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we consider an exact mu - tau reflection symmetry in neutrino sectorrealized at the gut scale in the context of the seesaw model with and without supersymmetry. assuming the two lighter heavy majorana neutrinos are degenerate at the gut scale, it is shown that the renormalization group ( rg ) evolution from the gut scale to the seesaw scale gives rise to breaking of the mu - tau symmetry and a tiny splitting between two degenerate heavy majorana neutrino masses as well as small variations of the cp phases in y _ nu, which are essential to achieve a successful leptogenesis. such small rg effects lead to tiny deviations of theta _ { 23 } from the maximal value and the cp phase delta _ { cp } from pi / 2 imposed at the gut scale due to mu - tau reflection symmetry. in our scenario, the required amount of the baryon asymmetry eta _ b can be generated via so - called resonant e - leptogenesis, in which the wash - out factor concerned with electron flavor plays a crucial role in reproducing a successful leptogenesis. we show that cp violation responsible for the generation of baryon asymmetry of our universe can be directly linked with cp violation measurable through neutrino oscillation as well as neutrino mixing angles theta _ { 12 } and theta _ { 13 }. we expect that, in addition to the reactor and long baseline neutrino experiments, the measurements for the supersymmetric parameter tan { beta } at future collider experiments would serve as an indirect test of our scenario of baryogenesis based on the mu - tau reflection symmetry.
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arxiv:0811.1458
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micro - drones can be integrated into various industrial applications but are constrained by their computing power and expert pilots, a secondary challenge. this study presents a computationally - efficient deep convolutional neural network that utilizes gabor filters and spatial separable convolutions with low computational complexities. an attention module is integrated with the model to complement the performance. further, perception - based action space and trajectory generators are integrated with the model ' s predictions for intuitive navigation. the computationally - efficient model aids a human operator in controlling a micro - drone via gestures. nearly 18 % of computational resources are conserved using the nvidia gpu profiler during training. using a low - cost dji tello drone for experiment verification, the computationally - efficient model shows promising results compared to a state - of - the - art and conventional computer vision - based technique.
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arxiv:2301.12470
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bekenstein and mukhanov ( bm ) have suggested that, in a quantum theory of gravity, black holes may have discrete emission spectra. using the time - energy uncertainty principle they have also shown that, for a ( non - rotating ) schwarzschild black hole, the natural broadening $ \ delta \ omega $ of the black - hole emission lines is expected to be small on the scale set by the characteristic frequency spacing $ \ delta \ omega $ of the spectral lines : $ \ zeta ^ { \ text { sch } } \ equiv \ delta \ omega / \ delta \ omega \ ll1 $. bm have therefore concluded that the expected discrete emission lines of the quantized schwarzschild black hole are unlikely to overlap. in this paper we calculate the characteristic dimensionless ratio $ \ zeta ( \ bar a ) \ equiv \ delta \ omega / \ delta \ omega $ for the predicted bm emission spectra of rapidly - rotating kerr black holes ( here $ \ bar a \ equiv j / m ^ 2 $ is the dimensionless angular momentum of the black hole ). it is shown that $ \ zeta ( \ bar a ) $ is an increasing function of the black - hole angular momentum. in particular, we find that the quantum emission lines of kerr black holes in the regime $ \ bar a \ gtrsim 0. 9 $ are characterized by the dimensionless ratio $ \ zeta ( \ bar a ) \ gtrsim1 $ and are therefore effectively blended together. our results thus suggest that, even if the underlying mass ( energy ) spectrum of these rapidly - rotating kerr black holes is fundamentally discrete as suggested by bekenstein and mukhanov, the natural broadening phenomenon ( associated with the time - energy uncertainty principle ) is expected to smear the black - hole radiation spectrum into a continuum.
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arxiv:1909.04057
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higher - order topological phases are gapped phases of matter that host gapless corner or hinge modes. for the case of superconductors, corner or hinge modes are gapless majorana modes or majorana zero modes. to construct 3d higher - order topological superconductors, we consider a topological - insulator / superconductor multilayer under in - plane zeeman coupling. we found three different types of higher - order topological superconductor phases, a second - order topological superconductor phase with majorana hinge flat bands, a second - order dirac superconductor phase with surface majorana cones and majorana hinge arcs, and nodal - line superconductor phases with drumhead surface states and majorana hinge arcs.
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arxiv:2307.13312
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there is growing evidence for high - frequency gravitational waves ( hfgws ) ranging from mhz to ghz. several hfgw detectors have been operating for over a decade, and two ghz events have been reported recently. however, a confirmed detection might take a decade. this essay argues that unexplained observed astrophysical phenomena, like fast radio bursts ( frbs ), might provide indirect evidence for hfgws. in particular, using the gertsenshtein - zel $ ' $ dovich effect, we show that our model can explain three key features of frbs : generate peak - flux up to $ 1000 ~ { \ rm jy } $, naturally explain the pulse width and the coherent nature of frbs. in short, our model offers a novel perspective on the indirection detection of hfgws beyond current detection capabilities. thus, transient events like frbs are a rich source for multi - messenger astronomy.
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arxiv:2311.11150
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the error model of a quantum computer is essential for optimizing quantum algorithms to minimize the impact of errors using quantum error correction or error mitigation. noise with temporal correlations, e. g. low - frequency noise and context - dependent noise, is common in quantum computation devices and sometimes even significant. however, conventional tomography methods have not been developed for obtaining an error model describing temporal correlations. in this paper, we propose self - consistent tomography protocols to obtain a model of temporally correlated errors, and we demonstrate that our protocols are efficient for low - frequency noise and context - dependent noise.
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arxiv:1811.02734
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edge - based network models, especially those based on bond percolation methods, can be used to model disease transmission on complex networks and accommodate social heterogeneity while keeping tractability. here we present an application of an edge - based network model to the spread of syphilis in the kingston, frontenac and lennox & addington ( kfl & a ) region of southeastern ontario, canada. we compared the results of using a network - based susceptible - infectious - recovered ( sir ) model to those generated from using a traditional mass action sir model. we found that the network model yields very different predictions, including a much lower estimate of the final epidemic size. we also used the network model to estimate the potential impact of introducing a rapid syphilis point of care test ( poct ) and treatment intervention strategy that has recently been implemented by the public health unit to mitigate syphilis transmission.
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arxiv:2410.13024
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modern image inpainting systems, despite the significant progress, often struggle with large missing areas, complex geometric structures, and high - resolution images. we find that one of the main reasons for that is the lack of an effective receptive field in both the inpainting network and the loss function. to alleviate this issue, we propose a new method called large mask inpainting ( lama ). lama is based on i ) a new inpainting network architecture that uses fast fourier convolutions ( ffcs ), which have the image - wide receptive field ; ii ) a high receptive field perceptual loss ; iii ) large training masks, which unlocks the potential of the first two components. our inpainting network improves the state - of - the - art across a range of datasets and achieves excellent performance even in challenging scenarios, e. g. completion of periodic structures. our model generalizes surprisingly well to resolutions that are higher than those seen at train time, and achieves this at lower parameter & time costs than the competitive baselines. the code is available at \ url { https : / / github. com / saic - mdal / lama }.
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arxiv:2109.07161
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barut ' s formula for the mass of leptons is successfully extended to quarks. a very simple non - linear scalar field model explains both the n ^ 4 power law dependence of the mass, and the existence of a cut - off which limits the number of leptons to three and the number of quarks to five, suggesting that the mass of the sixth quark is of different origin.
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arxiv:hep-ph/0201193
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there are many indications that anthropogenic global warming poses a serious threat to our civilization and its ecological support systems. ideally this problem will be overcome by reducing greenhouse gas emissions. various space - based methods, including large - scale solar shades, diffusers or atmospheric pollutants, have been considered to reduce the solar constant ( input flux ) and the warming in case emissions reductions are not achieved in a timely way. here it is pointed out that proposed technologies for near - earth orbiting comet deflection, suggest a different kind of space - based solar shade. this shade would be made up of micron - sized dust particles derived from comet fragments or lunar mining, and positioned in orbits near the triangular lagrange points of the earth - moon system. solar radiation pressure can render such orbits unstable, but a class of nearly resonant, and long - lived orbits is shown to exist, though the phase space volume of such orbits depends on dust grain size. advantages and disadvantages of this scheme relative to others are considered.
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arxiv:astro-ph/0701513
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we study fluctuations in the number of points of $ \ ell $ - cyclic covers of the projective line over the finite field $ \ mathbb { f } _ q $ when $ q \ equiv 1 \ mod \ ell $ is fixed and the genus tends to infinity. the distribution is given as a sum of $ q + 1 $ i. i. d. random variables. this was settled for hyperelliptic curves by kurlberg and rudnick, while statistics were obtained for certain components of the moduli space of $ \ ell $ - cyclic covers by bucur, david, feigon and lal \ ' { i } n. in this paper, we obtain statistics for the distribution of the number of points as the covers vary over the full moduli space of $ \ ell $ - cyclic covers of genus $ g $. this is achieved by relating $ \ ell $ - covers to cyclic function field extensions, and counting such extensions with prescribed ramification and splitting conditions at a finite number of primes.
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arxiv:1505.07136
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the decay k - - > pi0 e - nu is studied using in - flight decays detected with the istra + spectrometer. about 920k events are collected for the analysis. the lambda + slope parameter of the decay form - factor f + ( t ) in the linear approximation ( average slope ) is measured : lambda + ( lin ) = 0. 02774 + - 0. 00047 ( stat ) + - 0. 00032 ( syst ). the quadratic contribution to the form - factor was estimated to be lambda ' + = 0. 00084 + - 0. 00027 ( stat ) + - 0. 00031 ( syst ). the linear slope, which has a meaning of df + ( t ) / dt | _ { t = 0 } for this fit, is lambda + = 0. 02324 + - 0. 00152 ( stat ) + - 0. 00032 ( syst ). the limits on possible tensor and scalar couplings are derived : f _ { t } / f _ { + } ( 0 ) = - 0. 012 + - 0. 021 ( stat ) + - 0. 011 $ ( syst ), f _ { s } / f _ { + } ( 0 ) = - 0. 0037 ^ { + 0. 0066 } _ { - 0. 0056 } ( stat ) + - 0. 0041 ( syst ).
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arxiv:hep-ex/0404030
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we discuss the associativity or wdvv equations and demonstrate that they can be rewritten as certain functional relations between the { \ it second } derivatives of a single function, similar to the dispersionless hirota equations. the properties of these functional relations are further discussed.
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arxiv:hep-th/0205308
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the entanglement analysis of a pure state of a many - body quantum system requires a prior information about its density matrix / state matrix, obtained in principle by solving the hamiltonian matrix. the missing information due to complexity of the many - body interactions however renders it necessary to consider an ensemble of hamiltonians and thereby an ensemble of pure states. this in turn leaves a statistical description of the entanglement measures as the only option. we consider physical hamiltonians that can be modelled by a multiparametric gaussian ensembles, theoretically derive the state ensembles for its eigenstates and analyze the effect of varying system conditions on its entanglement statistics. our approach leads to a single parametric based common mathematical formulation for the evolution of the statistics of different state ensembles. the parameter turns out to be a single functional of the system parameters and thereby reveals a deep web of connection underlying different quantum states.
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arxiv:2503.01989
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multi - sample microarray experiments have become a standard experimental method for studying biological systems. a frequent goal in such studies is to unravel the regulatory relationships between genes. during the last few years, regression models have been proposed for the de novo discovery of cis - acting regulatory sequences using gene expression data. however, when applied to multi - sample experiments, existing regression based methods model each individual sample separately. to better capture the dynamic relationships in multi - sample microarray experiments, we propose a flexible method for the joint modeling of promoter sequence and multivariate expression data. in higher order eukaryotic genomes expression regulation usually involves combinatorial interaction between several transcription factors. experiments have shown that spacing between transcription factor binding sites can significantly affect their strength in activating gene expression. we propose an adaptive model building procedure to capture such spacing dependent cis - acting regulatory modules. we apply our methods to the analysis of microarray time - course experiments in yeast and in arabidopsis. these experiments exhibit very different dynamic temporal relationships. for both data sets, we have found all of the well - known cis - acting regulatory elements in the related context, as well as being able to predict novel elements.
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arxiv:0803.3904
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a good and robust sensor data fusion in diverse weather conditions is a quite challenging task. there are several fusion architectures in the literature, e. g. the sensor data can be fused right at the beginning ( early fusion ), or they can be first processed separately and then concatenated later ( late fusion ). in this work, different fusion architectures are compared and evaluated by means of object detection tasks, in which the goal is to recognize and localize predefined objects in a stream of data. usually, state - of - the - art object detectors based on neural networks are highly optimized for good weather conditions, since the well - known benchmarks only consist of sensor data recorded in optimal weather conditions. therefore, the performance of these approaches decreases enormously or even fails in adverse weather conditions. in this work, different sensor fusion architectures are compared for good and adverse weather conditions for finding the optimal fusion architecture for diverse weather situations. a new training strategy is also introduced such that the performance of the object detector is greatly enhanced in adverse weather scenarios or if a sensor fails. furthermore, the paper responds to the question if the detection accuracy can be increased further by providing the neural network with a - priori knowledge such as the spatial calibration of the sensors.
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arxiv:1807.02323
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it is challenging to implement genuine free running single photon detectors for the 1550 nm wavelength range with simultaneously high detection efficiency ( de ), low dark noise, and good time resolution. we report a novel read out system for the signals from a negative feedback avalanche diode ( nfad ) which allows useful operation of these devices at a temperature of 193 k and results in very low dark counts ( ~ 100 cps ), good time jitter ( ~ 30 ps ), and good de ( ~ 10 % ). we characterized two nfads with a time correlation method using photons generated from weak coherent pulses ( wcp ) and photon pairs produced by spontaneous parametric down conversion ( spdc ). the inferred detector efficiencies for both types of photon sources agree with each other. the best noise equivalent power of the device is estimated to be 8. 1 x 10 ^ ( - 18 ) w hz ^ ( - 1 / 2 ), more than 10 times better than typical inp / ingaas spads show in free running mode. the afterpulsing probability was found to be less than 0. 1 % per ns at the optimized operating point. in addition, we studied the performance of an entanglement - based quantum key distribution ( qkd ) using these detectors and develop a model for the quantum bit error rate ( qber ) that incorporates the afterpulsing coefficients. we verified experimentally that using these nfads it is feasible to implement qkd over 400 km of telecom fibre. our nfad photon detector system is very simple, and is well suited for single - photon applications where ultra - low noise and free - running operation is required, and some afterpulsing can be tolerated.
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arxiv:1201.2433
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using special quasirandom structures ( sqs ' s ), we perform first - principles calculations studying the metastable bcc nicu and fecu alloys which occur in fe - cu - ni alloy steels as precipitated second phase. the mixing enthalpies, density of state, and equilibrium lattice parameters of these alloys are reported. the results show that quasi - chemical approach and vegard rule can well predict the energetic and structural properties of fecu alloys but fail to yield that of nicu. the reason rests with the difference of bond energy variation with composition between nicu and fecu alloys induced by competition between ferromagnetic and paramagnetic state. furthermore, the calculated results show that the energetic and structural properties of these alloys can well explain the local composition of the corresponding precipitates in ferrite steels.
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arxiv:1102.4115
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we discuss the design for a discrete, immediate, simple relativistic positioning system ( rps ) which is potentially able of self - positioning ( up to isometries ) and operating without calibration or ground control assistance. the design is discussed in dimension two on spacetime ( i. e. one spatial dimension plus one time dimension ), in minkowski and schwarzschild solutions, as well as in dimension three ( i. e. two spatial dimensions plus one time dimension ) in minkowski. the system works without calibration, clock synchronizations, or a priori knowledge about the motion of clocks, it is able to self - diagnose hypotheses break down ( for example, if one clock temporarily becomes not - freely falling, or the gravitational field changes ) and it is automatically back and operational when the assumed conditions are restored. in the schwarzschild case, we show that the system can also best fit the gravitational mass of the source of the gravitational field and stress that no weak field assumptions are made anywhere. in particular, the rps we propose can work in a region close to the horizon since it does not use approximations or ppn expansions. more generally, the rps can be adapted as detectors for the gravitational field and we shall briefly discuss their role in testing different theoretical settings for gravity. in fact, rps is a natural candidate for a canonical method to extract observables out of a gravitational theory, an activity also known as designing experiments to test gravity.
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arxiv:1805.04741
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we study existence of nonnegative solutions to a nonlinear parabolic boundary value problem with a general singular lower order term and a nonnegative measure as nonhomogeneous datum, of the form $ $ \ begin { cases } \ displaystyle u _ t - \ delta _ p u = h ( u ) f + \ mu & \ text { in } \ \ omega \ times ( 0, t ), \ \ u = 0 & \ text { on } \ \ partial \ omega \ times ( 0, t ), \ \ u = u _ 0 & \ text { in } \ \ omega \ times \ { 0 \ }, \ end { cases } $ $ where $ \ omega $ is an open bounded subset of $ \ mathbb { r } ^ n $ ( $ n \ ge2 $ ), $ u _ 0 $ is a nonnegative integrable function, $ \ delta _ p $ is the $ p $ - laplace operator, $ \ mu $ is a nonnegative bounded radon measure on $ \ omega \ times ( 0, t ) $ and $ f $ is a nonnegative function of $ l ^ 1 ( \ omega \ times ( 0, t ) ) $. the term $ h $ is a positive continuous function possibly blowing up at the origin. furthermore, we show uniqueness of finite energy solutions in presence of a nonincreasing $ h $.
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arxiv:1901.01545
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in this paper we suggest analytical methods and associated algorithms for determining the sum of the subsets $ x _ m $ of the set $ x _ n $ ( subset sum problem ). our algorithm has time complexity $ t = o ( c _ { n } ^ { k } ) $ ( $ k = [ m / 2 ] $, which significantly improves upon all known algorithms. this algorithm is applicable to all np - complete problems. moreover, the algorithm has memory complexity $ m = o ( c _ n ^ k ) $, which makes our algorithm applicable to real - world problems. at first, we show how to use the algorithm for small dimensions $ m = 4, 5, 6, 7, 8 $. after that we establish a general methodology for $ m > 8 $. the main idea is to split the original set $ x _ n $ ( the algorithm becomes even faster with sorted sets ) into smaller subsets and use parallel computing. this approach might be a significant breakthrough towards finding an efficient solution to $ np $ - complete problems. as a result, it opens a way to prove the $ p $ versus np problem ( one of the seven millennium prize problems ).
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arxiv:2003.06571
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in their rocksalt structure, rare - earth monosulfides offer a more stable alternative to alkali metals to attain low or negative electron affinity when deposited on various iii - v and ii - vi semiconductor surfaces. in this article, we first describe the successful deposition of lanthanum monosulfide via pulsed laser deposition on si and mgo substrates and alumina templates. these thin films have been characterized by x - ray diffraction, atomic force microscopy, high resolution transmission electron microscopy, ellipsometry, raman spectroscopy, ultraviolet photoelectron spectroscopy and kelvin probe measurements. for both las / si and las / mgo thin films, the effective work function of the submicron thick thin films was determined to be about 1 ev from field emission measurements using the scanning anode field emission microscopy technique. the physical reasons for these highly desirable low work function properties were explained using a patchwork field emission model of the emitting surface. in this model, nanocrystals of low work function materials having a < 100 > orientation perpendicular to the surface and outcropping it are surrounded by a matrix of amorphous materials with higher work function. to date, las thin films have been used successfully as cold cathode emitters with measured emitted current densities as high as 50 a / cm2. finally, we describe the successful growth of las thin films on inp substrates and, more recently, the production of las nanoballs and nanoclusters using pulsed laser ablation.
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arxiv:1107.2547
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soft - core attractive potentials can give rise to a phase diagram with three fluid phases at different densities ( gas, low - density liquid and high - density liquid ), separated by first order phase transition lines ending in critical points. experiments show a phase diagram with these features for phosphorous and triphenyl - phosphite. liquid - liquid phase transition could be relevant for water, silica, liquid metals, colloids and protein solutions, among others. here we compare two potentials with short - range soft - core repulsion and narrow attraction. one of them is a squared potential that is known to have liquid - liquid phase transition, ending in a critical point, and no anomaly in density. the normal, monotonic, behavior of density for isobaric cooling is surprising if compared with molecular liquids, such as water, where a hypothetical critical point is proposed as rationale for the anomalous behavior of density. the second potential is a continuous version of the first. we show that the phase diagram associated to this new potential has, not only the liquid - liquid phase transition, but also the density anomaly. our result, therefore, shows that the behavior in density is strongly dependent on the derivative of the potential.
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arxiv:cond-mat/0703681
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support, or management of computer - based information systems ". the responsibilities of those working in the field include network administration, software development and installation, and the planning and management of an organization ' s technology life cycle, by which hardware and software are maintained, upgraded, and replaced. = = = information services = = = information services is a term somewhat loosely applied to a variety of it - related services offered by commercial companies, as well as data brokers. = = = ethics = = = the field of information ethics was established by mathematician norbert wiener in the 1940s. : 9 some of the ethical issues associated with the use of information technology include : : 20 – 21 breaches of copyright by those downloading files stored without the permission of the copyright holders employers monitoring their employees ' emails and other internet usage unsolicited emails hackers accessing online databases web sites installing cookies or spyware to monitor a user ' s online activities, which may be used by data brokers = = it projects = = research suggests that it projects in business and public administration can easily become significant in scale. work conducted by mckinsey in collaboration with the university of oxford suggested that half of all large - scale it projects ( those with initial cost estimates of $ 15 million or more ) often failed to maintain costs within their initial budgets or to complete on time. = = see also = = information and communications technology ( ict ) it infrastructure outline of information technology knowledge society = = notes = = = = references = = = = = citations = = = = = = bibliography = = = = = further reading = = allen, t. ; morton, m. s. morton, eds. ( 1994 ), information technology and the corporation of the 1990s, oxford university press. gitta, cosmas and south, david ( 2011 ). southern innovator magazine issue 1 : mobile phones and information technology : united nations office for south - south cooperation. issn 2222 - 9280. gleick, james ( 2011 ). the information : a history, a theory, a flood. new york : pantheon books. price, wilson t. ( 1981 ), introduction to computer data processing, holt - saunders international editions, isbn 978 - 4 - 8337 - 0012 - 2. shelly, gary, cashman, thomas, vermaat, misty, and walker, tim. ( 1999 ). discovering computers 2000 : concepts for a connected world. cambridge, massachusetts : course technology. webster, frank, and robins, kevin. ( 1986
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https://en.wikipedia.org/wiki/Information_technology
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in this paper, a preliminary correspondence between the thermodynamic curvature and the isoperimetric theorem is established from a $ 4 $ - dimensional ultraspinning black hole. we find that the thermodynamic curvature of ultraspinning black hole is negative which means the ultraspinning black hole is likely to present an attractive between its molecules phenomenologically if we accept the analogical observation that the thermodynamic curvature reflects the interaction between molecules in a black hole system. meanwhile we obtain a general conclusion that the thermodynamic curvature of the extreme black hole of the super - entropic black hole has a ( positive or negative ) remnant approximately proportional to the reciprocal of entropy of the black hole.
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arxiv:2006.00665
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lempel - ziv - double ( lzd ) is a variation of the lz78 compression scheme that achieves better compression on repetitive datasets. nevertheless, prior research has identified computational inefficiencies and a weakness in its compressibility for certain datasets. in this paper, we introduce lzd +, an enhancement of lzd, which enables expected linear - time online compression by allowing truncated references. to avoid the compressibility weakness exhibited by a lower bound example, we propose lzdr ( lzd - runlength compressed ), a further enhancement on top of lzd +, which introduces a repetition - based factorization rule while maintaining linear expected time complexity. the both time bounds can be de - randomized by a lookup data structure like a balanced search tree with a logarithmic dependency on the alphabet size. additionally, we present three flexible parsing variants of lzdr that yield fewer factors in practice. comprehensive benchmarking on standard corpora reveals that lzd +, lzdr, and its flexible variants outperform existing lz - based methods in the number of factors while keeping competitive runtime efficiency. however, we note that the difference in the number of factors becomes marginal for large datasets like those of the pizza & chili corpus.
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arxiv:2505.00970
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we report the first systematic measurements of the raman scattering by electrons in elemental metals of al, mo, nb, os, pb, re, ta, ti, v, w and metallic compound la $ b _ 6 $. experimental spectra are modelled on the base of the band structures, calculated within the density functional theory, taking properly into account the effects of electron - phonon scattering. the agreement between our measured and calculated spectra is excellent for the variety of metals, thus providing estimates for the electron - phonon coupling constants and temperature - dependent relaxation rates. the method can be applied for other metallic materials to evaluate an electron - phonon coupling as an alternative to the transport and optical measurements.
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arxiv:1204.4582
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modern latency - critical online services often rely on composing results from a large number of server components. hence the tail latency ( e. g. the 99th percentile of response time ), rather than the average, of these components determines the overall service performance. when hosted on a cloud environment, the components of a service typically co - locate with short batch jobs to increase machine utilizations, and share and contend resources such as caches and i / o bandwidths with them. the highly dynamic nature of batch jobs in terms of their workload types and input sizes causes continuously changing performance interference to individual components, hence leading to their latency variability and high tail latency. however, existing techniques either ignore such fine - grained component latency variability when managing service performance, or rely on executing redundant requests to reduce the tail latency, which adversely deteriorate the service performance when load gets heavier. in this paper, we propose pcs, a predictive and component - level scheduling framework to reduce tail latency for large - scale, parallel online services. it uses an analytical performance model to simultaneously predict the component latency and the overall service performance on different nodes. based on the predicted performance, the scheduler identifies straggling components and conducts near - optimal component - node allocations to adapt to the changing performance interferences from batch jobs. we demonstrate that, using realistic workloads, the proposed scheduler reduces the component tail latency by an average of 67. 05 \ % and the average overall service latency by 64. 16 \ % compared with the state - of - the - art techniques on reducing tail latency.
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arxiv:1511.02960
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in this paper, we establish the global existence and uniqueness of solution to $ 2 $ - d inhomogeneous incompressible navier - stokes equations \ eqref { 1. 2 } with initial data in the critical spaces. precisely, under the assumption that the initial velocity $ u _ 0 $ in $ l ^ 2 \ cap \ dot b ^ { - 1 + \ frac { 2 } { p } } _ { p, 1 } $ and the initial density $ \ rho _ 0 $ in $ l ^ \ infty $ and having a positive lower bound, which satisfies $ 1 - \ rho _ 0 ^ { - 1 } \ in \ dot b ^ { \ frac { 2 } { \ lambda } } _ { \ lambda, 2 } \ cap l ^ \ infty, $ for $ p \ in [ 2, \ infty [ $ and $ \ lambda \ in [ 1, \ infty [ $ with $ \ frac { 1 } { 2 } < \ frac { 1 } { p } + \ frac { 1 } { \ lambda } \ leq1, $ the system \ eqref { 1. 2 } has a global solution. the solution is unique if $ p = 2. $ with additional assumptions on the initial density in case $ p > 2, $ we can also prove the uniqueness of such solution. in particular, this result improves the previous work in \ cite { ag2021 } where $ u _ { 0 } $ belongs to $ \ dot { b } _ { 2, 1 } ^ { 0 } $ and $ \ rho _ 0 ^ { - 1 } - 1 $ belongs to $ \ dot { b } _ { \ frac { 2 } { \ varepsilon }, 1 } ^ { \ varepsilon } $, and we also remove the assumption that the initial density is close enough to a positive constant in \ cite { dw2023 } yet with additional regularities on the initial density here.
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arxiv:2312.03990
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diffusion language models ( dlms ) have emerged as a promising new paradigm for text generative modeling, potentially addressing limitations of autoregressive ( ar ) models. however, current dlms have been studied at a smaller scale compared to their ar counterparts and lack fair comparison on language modeling benchmarks. additionally, training diffusion models from scratch at scale remains challenging. given the prevalence of open - source ar language models, we propose adapting these models to build text diffusion models. we demonstrate connections between ar and diffusion modeling objectives and introduce a simple continual pre - training approach for training diffusion models. through systematic evaluation on language modeling, reasoning, and commonsense benchmarks, we show that we can convert ar models ranging from 127m to 7b parameters ( gpt2 and llama ) into diffusion models diffugpt and diffullama, using less than 200b tokens for training. our experimental results reveal that these models outperform earlier dlms and are competitive with their ar counterparts. we release a suite of dlms ( 127m - 355m - 7b ) capable of generating fluent text, performing in - context learning, filling in the middle without prompt re - ordering, and following instructions https : / / github. com / hkunlp / diffullama.
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arxiv:2410.17891
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we extend the infinitesimal torelli theorem for smooth hypersurfaces to nodal hypersurfaces.
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arxiv:1703.03324
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we discuss a current dynamics on the surface of a 3 - dimensional topological insulator induced by magnetization precession of a ferromagnet attached. it is found that the magnetization dynamics generates a direct charge current when the precession axis is within the surface plane. this rectification effect is due to a quantum anomaly and is topologically protected. the robustness of the rectification effect against first - varying exchange field and impurities is confirmed by explicit calculation.
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arxiv:1109.6816
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we study the ground state properties of the holstein - hubbard model on some bipartite lattices at half - filling ; the ground state is proved to exhibit ferrimagnetism whenever the electron - phonon interaction is not so strong. in addition, the antiferromagnetic long range order is shown to exist in the ground state. in contrast to this, we prove the absence of the long range charge order.
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arxiv:1610.09039
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we present a transport study of semi - metallic bismuth in presence of a magnetic field applied along the trigonal axis extended to 55 t for electric conductivity and to 45 t for thermoelectric response. the results uncover a new field scale at about 40 t in addition to the previously detected ones. large anomalies in all transport properties point to an intriguing electronic instability deep in the ultraquantum regime. unexpectedly, both the sheer magnitude of conductivity and its metallic temperature dependence are enhanced by this instability.
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arxiv:0905.3835
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in this paper, we study a class of non - weight modules over the affine - virasoro algebra of type $ a _ 1 $, which are free modules of rank one when restricted to the cartan subalgebra ( modulo center ). we give the classification of such modules. moreover, the simplicity and the isomorphism classes of these modules are determined.
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arxiv:1904.10334
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the propensity of some materials and multilayers to have a magnetic field dependent resistance, called magnetoresistance, has found commercial applications such as giant magnetoresistance harddisk read heads. but magnetoresistance can also be a powerful probe of electronic and magnetic interactions in matter. for example, magnetoresistance can be used to analyze multiband conductivity, conduction inhomogeneity, localized magnetic moments, and ( fractional ) landau level structure. for materials with strong spin - orbit interaction, magnetoresistance can be used as a probe for weak antilocalization or a nontrivial berry phase, such as in topological insulator surface states. for the three dimensional topological insulators a large and linear magnetoresistance is often used as indication for underlying non - trivial topology, although the origin of this effect has not yet been established. here, we observe a large magnetoresistance in the conducting bulk state of bi $ _ 2 $ te $ _ 3 $. we show that this type of large magnetoresistance is due to the competition between helical spin - momentum locking ( i. e. spin rotates with momentum direction ) and the unidirectional spin alignment by an applied magnetic field. warping effects are found to provide the ( quasi ) linear dependence on magnetic field. we provide a quantitative model for the helicity breaking induced magnetoresistance that can be applied to a vast range of materials, surfaces or interfaces with weak to strong spin - orbit interactions, such as the contemporary oxide interfaces, bulk rashba systems, and topological insulator surface states.
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arxiv:1412.4065
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galaxy assembly bias, the correlation between galaxy properties and halo properties at fixed halo mass, could be an important ingredient in halo - based modelling of galaxy clustering. we investigate the central galaxy assembly bias by studying the relation between various galaxy and halo properties in the illustris hydrodynamic galaxy formation simulation. galaxy stellar mass $ \ mstar $ is found to have a tighter correlation with peak maximum halo circular velocity $ \ vp $ than with halo mass $ \ mh $. once the correlation with $ \ vp $ is accounted for, $ \ mstar $ has nearly no dependence on any other halo assembly variables. the correlations between galaxy properties related to star formation history and halo assembly properties also show a cleaner form as a function of $ \ vp $ than as a function of $ \ mh $, with the main correlation being with halo formation time and to a less extent halo concentration. based on the galaxy - halo relation, we present a simple model to relate the bias factors of a central galaxy sample and the corresponding halo sample, both selected based on assembly - related properties. it is found that they are connected by the correlation coefficient of the galaxy and halo properties used to define the two samples, which provides a reasonable description for the samples in the simulation and suggests a simple prescription to incorporate galaxy assembly bias into the halo model. by applying the model to the local galaxy clustering measurements in lin et al. ( 2016 ), we infer that the correlation between star formation history or specific star formation rate and halo formation time is consistent with being weak.
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arxiv:1812.11210
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: hep - th / 0005259 ]. in this paper we find some recurrence relations that give a possible to find all $ n ( i _ 0 \ bigl | i _ 1,..., i _ k | \ bar i _ 1,..., \ bar i _ { \ bar k } ) $.
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arxiv:math/0103136
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in this paper we study different restrictions imposed over the set of permutations of size $ n $, $ s _ n $, and for specific classes of restrictions study the cycle structure of corresponding permutations. more specifically, we prove that for any fixed positive integer $ k $, the number of $ k $ - cycles of a uniformly chosen permutation $ \ pi \ in s _ n $ with the restriction " $ \ pi ( i ) \ geq i - 1 $ " for $ i \ in \ { 2, \ ldots, n \ } $ has a normal asymptotic distribution. we further prove that this result translates into clts regarding multiplicities of fixed - size parts of a uniformly selected composition of $ n $.
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arxiv:1710.07885
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the $ \ bar { \ partial } $ - neumann operator ( the inverse of the complex laplacian ) is shown to be noncompact on certain domains in complex euclidean space. these domains are either higher - dimensional analogs of the hartogs triangle, or have such a generalized hartogs triangle imbedded appropriately in them.
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arxiv:1106.5167
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we calculate the degree of horizon smoothness of multi - $ m2 $ - brane solution with branes along a common axis. we find that the metric is generically only thrice continuously differentiable at any of the horizons. the four - form field strength is found to be only twice continuously differentiable. we work with gaussian null - like co - ordinates which are obtained by solving geodesic equations for multi - $ m2 $ brane geometry. we also find different, exact co - ordinate transformations which take the metric from isotropic co - ordinates to co - ordinates in which metric is thrice differentiable at the horizon. both methods give the same result that the multi - $ m2 $ brane metric is only thrice continuously differentiable at the horizon.
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arxiv:1202.4915
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high - $ \ sigma $ outflow.
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arxiv:1808.00636
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##y } ( | a _ { n } | + | b _ { n } | ) | z | ^ { n } \ leq d ( f ( 0 ), \ partial f ( \ mathbb { d } ) ) $ $ holds for $ | z | = r \ leq r _ { f } $ for the classes $ \ mathcal { hc } ( \ phi ) $ and $ \ mathcal { hc } _ { c } ( \ phi ) $. as a consequence of these results, we obtain several interesting corollaries on bohr inequality for the aforesaid classes.
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arxiv:2009.08683
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we explore the density variation of the correlation coefficient of the key parameters of the nuclear equation of state ( eos ) with the bulk and crustal properties of neutron stars. the analysis was performed using two diverse sets of nuclear effective interaction theories based on nonrelativistic skyrme - hartree fock model and relativistic mean field model. we find that the commonly studied eos parameters, namely the isoscalar incompressibility of symmetric nuclear matter $ k ( \ rho ) $ and the isovector slope of symmetry energy $ l ( \ rho ) $, reveal consistently maximum correlation with the radius, tidal deformability, and moment of inertia all around twice the saturation density. we find even more tighter and robust correlations beyond the saturation density for constructed parameter $ \ eta = [ kl ^ 2 ] ^ { 1 / 3 } $ allowing the possibility to impose stringent constraint on high - density $ k ( \ rho ) $ and $ l ( \ rho ) $. extensive correlation analysis of the eos parameters with the radius and tidal deformability bounds from gravitational wave gw190814 event allows us to provide reliable constraints on the central values of $ k ( \ rho _ 0 ) \ approx 248 $ mev and $ l ( \ rho _ 0 ) \ approx 65 $ mev at the saturation density and $ k ( 1. 6 \ rho _ 0 ) \ approx 391 - 517 $ mev and $ l ( 1. 6 \ rho _ 0 ) \ approx 153 - 169 $ mev at 1. 6 times the saturation density. the crust - core transition density and the crustal fraction of moment of inertia is shown to correlate more strongly with $ l ( \ rho ) $ and $ \ eta ( \ rho ) $ near the subsaturation density.
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arxiv:2503.01326
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there is a casimir force between two metal plates. it is generally believed that the casimir force is mediated by virtual photons in a vacuum, which correspond to the massless intermediate particles used in our theoretical calculations. studies have shown that not only virtual photons in a vacuum, but also other virtual particles that have masses. the lightest chargeless virtual particles with mass are positronium ( 1 mev ) and $ \ pi ^ { 0 } $ mesons ( 135 mev ). this paper primarily focuses on studying the corrections to the casimir force caused by positronium and $ \ pi ^ { 0 } $ mesons. especially when the distance between the two plates is on the order of $ 1 / m _ { positronium } $, the contribution of positronium becomes significant, and on the order of $ 1 / m _ { \ pi ^ 0 } $, the contribution of the $ \ pi ^ { 0 } $ meson becomes significant. we hope that the calculation results can reduce the error in the theoretical calculation of the casimir force when the distance between the plates is large and provide significant corrections when the distance is small.
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arxiv:2307.14506
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we present a preliminary direct measurement of the parity violating coupling of the z boson to strange quarks, a _ s, derived from a sample of approximately 300, 000 hadronic decays of z bosons produced with a polarized electron beam and recorded by the sld experiment at slac between 1993 and 1997. events with primary strange quarks are tagged by the presence in each event hemisphere of a high - momentum charged k meson, neutral k meson or lambda hyperon identified using the cherenkov ring imaging detector and / or a mass tag. the ccd vertex detector is used to suppress the background from heavy flavor events. the strangeness of the tagged particle is used to sign the event thrust axis in the direction of the initial strange quark. the coupling a _ s is obtained directly from a measurement of the left - right - forward - backward production asymmetry in polar angle of the tagged strange quark. to reduce the model dependence of the measurement, the background from primary up and down events is measured from the data, as is the analyzing power of the method for primary strange events. we measure a _ s = 0. 82 + - 0. 10 ( stat. ) + - 0. 08 ( syst. ) ( preliminary ).
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arxiv:hep-ex/9903003
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we characterize simply connected john domains in the plane with the aid of weak tangents of the boundary. specifically, we prove that a bounded simply connected domain $ d $ is a john domain if and only if, for every weak tangent $ y $ of $ \ partial d $, every connected component of the complement of $ y $ that ` ` originates " from $ d $ is a john domain, not necessarily with uniform constants. our main theorem improves a result of kinneberg ( arxiv : 1507. 04698 ), who obtains a necessary condition for a john domain in terms of weak tangents but not a sufficient one. we also establish several properties of weak tangents of john domains.
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arxiv:2501.18425
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it is shown that the singular seesaw mechanism can simultaneously explain all the existing data supporting nonzero neutrino masses and mixing. the three mass - squared differences that are needed to accommodate the atmospheric neutrino data ( through $ \ nu _ \ mu - \ nu _ s $ oscillation ), the solar neutrino data via msw mechanism ( through $ \ nu _ e - \ nu _ \ tau $ oscillation ), and the positive result of $ \ nu _ \ mu - \ nu _ e $ oscillation from lsnd can be generated by this mechanism, whereas the vacuum oscillation solution to the solar neutrino problem is disfavored. we find that the electron and tau neutrino masses are of order $ 10 ^ { - 3 } $ ev, and the muon neutrino and a sterile neutrino are almost maximally mixed to give a mass of order 1 ev. two heavy sterile neutrinos have a mass of order 1 kev which can be obtained by the double seesaw mechanism with an intermediate mass scale $ \ sim 10 ^ 5 $ gev. a possible origin of such a scale is discussed.
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arxiv:hep-ph/9802209
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a new approach, called adaptive q - control, for tapping - mode atomic force microscopy ( afm ) is introduced and implemented on a home - made afm set - up utilizing a laser doppler vibrometer ( ldv ) and a piezo - actuated bimorph probe. in the standard q - control, the effective q - factor of the scanning probe is adjusted prior to the scanning depending on the application. however, there is a trade - off in setting the effective q - factor of an afm probe. the q - factor is either increased to reduce the tapping forces or decreased to increase the maximum achievable scan speed. realizing these two benefits simultaneously using the standard q - control is not possible. in adaptive q - control, the q - factor of the probe is set to an initial value as in standard q - control, but then modified on the fly during scanning when necessary to achieve this goal. in this paper, we present the basic theory behind the adaptive q - control, the electronics enabling the on - line modification of the probe ' s effective q - factor, and the results of the experiments comparing three different methods : scanning a ) without q - control, b ) with the standard q - control, and c ) with the adaptive q - control. the results show that the performance of the adaptive q - control is superior to the other two methods.
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arxiv:1204.3011
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magnonics is gaining momentum as an emerging technology for information processing. the wave character and joule heating - free propagation of spin - waves hold promises for highly efficient analog computing platforms, based on integrated magnonic circuits. miniaturization is a key issue but, so far, only few examples of manipulation of spin - waves in nanostructures have been demonstrated, due to the difficulty of tailoring the nanoscopic magnetic properties with conventional fabrication techniques. in this letter, we demonstrate an unprecedented degree of control in the manipulation of spin - waves at the nanoscale by using patterned reconfigurable spin - textures. by space and time - resolved scanning transmission x - ray microscopy imaging, we provide direct evidence for the channeling and steering of propagating spin - waves in arbitrarily shaped nanomagnonic waveguides based on patterned domain walls, with no need for external magnetic fields or currents. furthermore, we demonstrate a prototypic nanomagnonic circuit based on two converging waveguides, allowing for the tunable spatial superposition and interaction of confined spin - waves modes.
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arxiv:1712.08293
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the tripartite graph is one of the commonest topological structures in social tagging systems such as delicious, which has three types of nodes ( i. e., users, urls and tags ). traditional recommender systems developed based on collaborative filtering for the social tagging systems bring very high demands on cpu time cost. in this paper, to overcome this drawback, we propose a novel approach that extracts non - overlapping user clusters and corresponding overlapping item clusters simultaneously through coarse clustering to accelerate the user - based collaborative filtering and develop a fast recommendation algorithm for the social tagging systems. the experimental results show that the proposed approach is able to dramatically reduce the processing time cost greater than $ 90 \ % $ and relatively enhance the accuracy in comparison with the ordinary user - based collaborative filtering algorithm.
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arxiv:1512.08325
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we propose a new topological field theory on generalized complex geometry in two dimension using aksz formulation. zucchini ' s model is $ a $ model in the case that the generalized complex structuredepends on only a symplectic structure. our new model is $ b $ model in the case that the generalized complex structure depends on only a complex structure.
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arxiv:0704.1015
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in this letter, we investigate a novel quadrature spatial scattering modulation ( qssm ) transmission technique based on millimeter wave ( mmwave ) systems, in which the transmitter generates two orthogonal beams targeting candidate scatterers in the channel to carry the real and imaginary parts of the conventional signal, respectively. meanwhile, the maximum likelihood ( ml ) detector is adopted at the receiver to recover the received beams and signals. based on the ml detector, we derive the closed - form average bit error probability ( abep ) expression of the qssm scheme. furthermore, we evaluate the asymptotic abep expression of the proposed scheme. monte carlo simulations verify the exactness and tightness of the derivation results. it is shown that the abep performance of qssm is better than that of traditional spatial scattering modulation.
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arxiv:2303.13806
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articulated human pose estimation is a fundamental yet challenging task in computer vision. the difficulty is particularly pronounced in scale variations of human body parts when camera view changes or severe foreshortening happens. although pyramid methods are widely used to handle scale changes at inference time, learning feature pyramids in deep convolutional neural networks ( dcnns ) is still not well explored. in this work, we design a pyramid residual module ( prms ) to enhance the invariance in scales of dcnns. given input features, the prms learn convolutional filters on various scales of input features, which are obtained with different subsampling ratios in a multi - branch network. moreover, we observe that it is inappropriate to adopt existing methods to initialize the weights of multi - branch networks, which achieve superior performance than plain networks in many tasks recently. therefore, we provide theoretic derivation to extend the current weight initialization scheme to multi - branch network structures. we investigate our method on two standard benchmarks for human pose estimation. our approach obtains state - of - the - art results on both benchmarks. code is available at https : / / github. com / bearpaw / pyranet.
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arxiv:1708.01101
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in this paper, we consider the optimal dividends problem for a company whose cash reserves follow a general levy process with certain positive jumps and arbitrary negative jumps. the objective is to find a policy which maximizes the expected discounted dividends until the time of ruin. under appropriate conditions, we appeal to very recent results in the theory of potential analysis of subordinators to obtain the convexity properties of probability of ruin. we present conditions under which the optimal dividend strategy, among all admissible ones, takes the form of a barrier strategy.
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arxiv:1101.0449
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the search for new materials for energy - efficient electronic devices has gained unprecedented importance. among the various classes of magnetic materials driving this search are antiferromagnets, magnetoelectrics, and systems with topological spin excitations. cu $ _ 3 $ teo $ _ 6 $ is a material that belongs to all three of these classes. combining static electric polarization and magnetic torque measurements with phenomenological simulations we demonstrate that magnetic - field - induced spin reorientation needs to be taken into account to understand the linear magnetoelectric ( me ) effect in cu $ _ 3 $ teo $ _ 6 $. our calculations reveal that the magnetic field pushes the system from the nonpolar ground state to the polar magnetic structures. however, nonpolar structures only weakly differing from the obtained polar ones exist due to the weak effect that the field - induced breaking of some symmetries has on the calculated structures. among those symmetries is the $ pt $ ( $ \ overline { 1 } ' $ ) symmetry, preserved for dirac points found in cu $ _ 3 $ teo $ _ 6 $. our findings establish cu $ _ 3 $ teo $ _ 6 $ as a promising playground to study the interplay of spintronics - related phenomena.
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arxiv:2211.08902
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intelligent reflecting surface ( irs ) has recently been identified as a prominent technology with the ability of enhancing wireless communication by dynamically manipulating the propagation environment. this paper investigates a multiple - input single - output ( miso ) system deploying distributed irss. for practical considerations, we propose an efficient design of passive reflecting beamforming for the irss to exploit statistical channel state information ( csi ) and analyze the achievable rate of the network taking into account the impact of csi estimation error. the ergodic achievable rate is derived in a closed form, which provides insightful system design guidelines. numerical results confirm the accuracy of the derived results and unveil the performance superiority of the proposed distributed irs deployment over the conventional centralized deployment.
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arxiv:2009.06286
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it is established that there exists a direct link between the formation history of star cluster populations and their host galaxies, however, our lacking understanding of star cluster assembly prohibits us to make full use of their ability to trace galaxy evolution. in this work we introduce a new variation of the 2020 version of the semi - analytical galaxy formation model " l - galaxies " that includes the formation of star clusters above 10 ^ 4 m _ sun and probes different physical assumptions that affect their evolution over cosmic time. we use properties of different galaxy components and localised star formation to determine the bound fraction of star formation in disks. after randomly sampling masses from an environmentally - dependent star cluster initial mass function, we assign to each object a half - mass radius, metallicity, and distance from the galaxy centre. we consider up to 2000 individual star clusters per galaxy and evolve their properties over time taking into account stellar evolution, two - body relaxation, tidal shocks, dynamical friction, and a re - positioning during galaxy mergers. our simulation successfully reproduces several observational quantities, such as the empirical relationship between the absolute v - band magnitude of the brightest young star clusters and the host galaxy star formation rate, the mass function of young star clusters, or mean metallicities of the star cluster distributions versus galaxy masses. the simulation reveals great complexity in the z = 0 star cluster population resulting from differential destruction channels and origins, including in - situ populations in the disk, a major merger - induced heated component in the halo, and accreted star clusters. model variations point out the importance of e. g. the shape of the star cluster initial mass function or the relationship between the sound speed of cold gas and the star formation rate.
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arxiv:2504.12079
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this article gives a brief overview of some recent advances in our understanding of the physics of dense strongly interacting matter, from measurements done at the cern sps. the presently available results are very interesting, and are likely to reflect the production of a new state of matter in central pb - pb collisions, at the highest sps energies. however, important questions require further work. particular emphasis is given to developments made since the quark matter 1999 conference, and to issues that justify the continuation of the sps heavy ion physics program beyond year 2000.
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arxiv:hep-ex/0105053
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active learning for sentence understanding attempts to reduce the annotation cost by identifying the most informative examples. common methods for active learning use either uncertainty or diversity sampling in the pool - based scenario. in this work, to incorporate both predictive uncertainty and sample diversity, we propose virtual adversarial perturbation for active learning ( vapal ), an uncertainty - diversity combination framework, using virtual adversarial perturbation ( miyato et al., 2019 ) as model uncertainty representation. vapal consistently performs equally well or even better than the strong baselines on four sentence understanding datasets : agnews, imdb, pubmed, and sst - 2, offering a potential option for active learning on sentence understanding tasks.
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arxiv:2210.14576
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we study the effectiveness of contextualized embeddings for the task of diachronic semantic change detection for russian language data. evaluation test sets consist of russian nouns and adjectives annotated based on their occurrences in texts created in pre - soviet, soviet and post - soviet time periods. elmo and bert architectures are compared on the task of ranking russian words according to the degree of their semantic change over time. we use several methods for aggregation of contextualized embeddings from these architectures and evaluate their performance. finally, we compare unsupervised and supervised techniques in this task.
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arxiv:2010.03481
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autonomous aerial cinematography has the potential to enable automatic capture of aesthetically pleasing videos without requiring human intervention, empowering individuals with the capability of high - end film studios. current approaches either only handle off - line trajectory generation, or offer strategies that reason over short time horizons and simplistic representations for obstacles, which result in jerky movement and low real - life applicability. in this work we develop a method for aerial filming that is able to trade off shot smoothness, occlusion, and cinematography guidelines in a principled manner, even under noisy actor predictions. we present a novel algorithm for real - time covariant gradient descent that we use to efficiently find the desired trajectories by optimizing a set of cost functions. experimental results show that our approach creates attractive shots, avoiding obstacles and occlusion 65 times over 1. 25 hours of flight time, re - planning at 5 hz with a 10 s time horizon. we robustly film human actors, cars and bicycles performing different motion among obstacles, using various shot types.
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arxiv:1808.09563
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we study uncertainty quantification for partial differential equations subject to domain uncertainty. we parameterize the random domain using the model recently considered by chernov and le ( 2024 ) as well as harbrecht, schmidlin, and schwab ( 2024 ) in which the input random field is assumed to belong to a gevrey smoothness class. this approach has the advantage of being substantially more general than models which assume a particular parametric representation of the input random field such as a karhunen - loeve series expansion. we consider both the poisson equation as well as the heat equation and design randomly shifted lattice quasi - monte carlo ( qmc ) cubature rules for the computation of the expected solution under domain uncertainty. we show that these qmc rules exhibit dimension - independent, essentially linear cubature convergence rates in this framework. in addition, we complete the error analysis by taking into account the approximation errors incurred by dimension truncation of the random input field and finite element discretization. numerical experiments are presented to confirm the theoretical rates.
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arxiv:2502.12345
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in an indirect gaussian sequence space model lower and upper bounds are derived for the concentration rate of the posterior distribution of the parameter of interest shrinking to the parameter value $ \ theta ^ \ circ $ that generates the data. while this establishes posterior consistency, however, the concentration rate depends on both $ \ theta ^ \ circ $ and a tuning parameter which enters the prior distribution. we first provide an oracle optimal choice of the tuning parameter, i. e., optimized for each $ \ theta ^ \ circ $ separately. the optimal choice of the prior distribution allows us to derive an oracle optimal concentration rate of the associated posterior distribution. moreover, for a given class of parameters and a suitable choice of the tuning parameter, we show that the resulting uniform concentration rate over the given class is optimal in a minimax sense. finally, we construct a hierarchical prior that is adaptive. this means that, given a parameter $ \ theta ^ \ circ $ or a class of parameters, respectively, the posterior distribution contracts at the oracle rate or at the minimax rate over the class. notably, the hierarchical prior does not depend neither on $ \ theta ^ \ circ $ nor on the given class. moreover, convergence of the fully data - driven bayes estimator at the oracle or at the minimax rate is established.
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arxiv:1502.00184
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we evaluate the longitudinal or ( chromo - ) electric yang - mills gluon propagator in the recently proposed center - symmetric landau gauge at finite temperature [ 1 ]. to model the effect of the gribov copies in the infrared, we use the curci - ferrari model which, in turn, allows us to rely on perturbative calculations. at one - loop order in the su ( 2 ) case, the so - obtained longitudinal gluon propagator provides a clear signature for z2 center - symmetry breaking with a singular behavior, characteristic of a continuous phase transition. this is in sharp contrast with what is found within the standard landau gauge. we also identify various signatures for z3 center - symmetry breaking in the su ( 3 ) case in the form of genuine order parameters. among those, we find that the gluon propagator, although degenerate along the diagonal color directions in the confining phase, becomes non - degenerate in the deconfined phase. our results open new ways of identifying the transition from correlation functions both within continuum approaches and on the lattice.
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arxiv:2206.03841
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we consider the effect of an energy - dependent dipole form factor in the high - energy behavior of the forward amplitude. the connection between the semihard parton - level dynamics and the hadron - hadron scattering is established by an eikonal qcd - based model. our results for the proton - proton ( $ pp $ ) and antiproton - proton ( $ \ bar { p } p $ ) total cross sections, $ \ sigma _ { tot } ^ { pp, \ bar { p } p } ( s ) $, obtained using the cteq6l1 parton distribution function, are consistent with the recent data from the totem experiment.
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arxiv:1508.07359
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we assume a condition on the zeros of dirichlet l - functions related to the gue distribution to show there are no discriminants greater than d _ { 66 } \ approx 1. 9 x 10 ^ { 130 } with one class per genus.
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arxiv:math/0401334
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