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amongst the population of tev gamma - ray sources detected with the high energy stereoscopic system ( h. e. s. s. ) in the galactic plane, clearly identified supernova remnant ( snr ) shells constitute a small but precious source class. tev - selected snrs are prime candidates for sources of efficient cosmic - ray acceleration. in this work, we present new snr candidates that have been identified in the entire h. e. s. s. phase i data set of the galactic plane recorded over the past ten years. identification with a known snr shell candidate was successful for one new source, hess j1534 - 571. in other cases, tev - only shell candidates are challenging to firmly identify as snrs due to their lack of detected non - thermal emission in lower energy bands. we will discuss how these objects may present an important link between young and evolved snrs, since their shell emission may be dominated by hadronic processes.
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arxiv:1509.03872
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the thermodynamical properties of dark energy are usually investigated with the equation of state $ \ omega = \ omega _ { 0 } + \ omega _ { 1 } z $. recent observations show that our universe is accelerating, and the apparent horizon and the event horizon vary with redshift $ z $. when definitions of the temperature and entropy of a black hole are used to the two horizons of the universe, we examine the thermodynamical properties of the universe which is enveloped by the apparent horizon and the event horizon respectively. we show that the first and the second laws of thermodynamics inside the apparent horizon in any redshift are satisfied, while they are broken down inside the event horizon in some redshift. therefore, the apparent horizon for the universe may be the boundary of thermodynamical equilibrium for the universe like the event horizon for a black hole.
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arxiv:0709.2745
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we study both the static and dynamic properties of gapped, one - dimensional, heisenberg, anti - ferromagnetic, spin chains at finite temperature through an analysis of the o ( 3 ) non - linear sigma model. exploiting the integrability of this theory, we are able to compute an exact low temperature expansion of the finite temperature correlators. we do so using a truncated ` form - factor ' expansion and so provide evidence that this technique can be successfully extended to finite temperature. as a direct test, we compute the static zero - field susceptibility and obtain an exact match to the susceptibility derived from the low temperature expansion of the exact free energy. we also study transport properties, computing both the spin conductance and the nmr - relaxation rate, 1 / t _ 1. we find these quantities to show ballistic behaviour. in particular, the computed spin conductance exhibits a non - zero drude weight at finite temperature and zero applied field. the physics thus described differs from the spin diffusion reported by takigawa et al. from experiments on the haldane gap material, agvp _ 2s _ 6.
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arxiv:cond-mat/0105284
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in this paper, by making use of the perturbative expansion around topological field theory we are trying to understand why the standard perturbation theory for general relativity, which starts with linearized gravity does not see gravitational collapse. we start with investigating classical equations of motion. for zero immirzi parameter the ambiguity of the standard perturbative expansion is reproduced. this ambiguity is related to the appearance of the linearized diffeomorphism symmetry, which becomes unlinked from the original diffeomorphism symmetry. introducing immirzi parameter makes it possible to restore the link between these two symmetries and thus removes the ambiguity, but at the cost of making classical perturbation theory rather intractable. then we argue that the two main sources of complexity of perturbation theory, infinite number of degrees of freedom and non - trivial curvature of the phase space of general relativity could be disentangled when studying { \ it quantum } amplitudes. as an illustration we consider zero order approximation in quantum perturbation theory. we identify relevant observables, and sketch their quantization. we find some indications that this zero order approximation might be described by doubly special relativity.
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arxiv:gr-qc/0612093
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geometric predicates are a basic ingredient to implement a vast range of algorithms in computational geometry. modern implementations employ floating point filtering techniques to combine efficiency and robustness, and state - of - the - art predicates are guaranteed to be always exact while being only slightly slower than corresponding ( inexact ) floating point implementations. unfortunately, if the input to these predicates is an intermediate construction of an algorithm, its floating point representation may be affected by an approximation error, and correctness is no longer guaranteed. this paper introduces the concept of indirect geometric predicate : instead of taking the intermediate construction as an explicit input, an indirect predicate considers the primitive geometric elements which are combined to produce such a construction. this makes it possible to keep track of the floating point approximation, and thus to exploit efficient filters and expansion arithmetic to exactly resolve the predicate with minimal overhead with respect to a naive floating point implementation. as a representative example, we show how to extend standard predicates to the case of points of intersection of linear elements ( i. e. lines and planes ) and show that, on classical problems, this approach outperforms state - of - the - art solutions based on lazy exact intermediate representations.
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arxiv:2105.09772
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a representation for the kernel of the transmutation operator relating the perturbed bessel equation with the unperturbed one is obtained in the form of a functional series with coefficients calculated by a recurrent integration procedure. new properties of the transmutation kernel are established. a new representation of the regular solution of the perturbed bessel equation is given presenting a remarkable feature of uniform error bound with respect to the spectral parameter for partial sums of the series. a numerical illustration of application to the solution of dirichlet spectral problems is presented.
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arxiv:1712.01363
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we set conservative, robust constraints on the annihilation and decay of dark matter into various standard model final states under various assumptions about the distribution of the dark matter in the milky way halo. we use the inclusive photon spectrum observed by the fermi gamma - ray space telescope through its main instrument, the large - area telescope ( lat ). we use simulated data to first find the " optimal " regions of interest in the gamma - ray sky, where the expected dark matter signal is largest compared with the expected astrophysical foregrounds. we then require the predicted dark matter signal to be less than the observed photon counts in the a priori optimal regions. this yields a very conservative constraint as we do not attempt to model or subtract astrophysical foregrounds. the resulting limits are competitive with other existing limits, and, for some final states with cuspy dark - matter distributions in the galactic center region, disfavor the typical cross section required during freeze - out for a weakly interacting massive particle ( wimp ) to obtain the observed relic abundance.
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arxiv:1503.07169
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connecting optimal transport and variational inference, we present a principled and systematic framework for sampling and generative modelling centred around divergences on path space. our work culminates in the development of the \ emph { controlled monte carlo diffusion } sampler ( cmcd ) for bayesian computation, a score - based annealing technique that crucially adapts both forward and backward dynamics in a diffusion model. on the way, we clarify the relationship between the em - algorithm and iterative proportional fitting ( ipf ) for schr { \ " o } dinger bridges, deriving as well a regularised objective that bypasses the iterative bottleneck of standard ipf - updates. finally, we show that cmcd has a strong foundation in the jarzinsky and crooks identities from statistical physics, and that it convincingly outperforms competing approaches across a wide array of experiments.
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arxiv:2307.01050
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as machine learning gains prominence in various sectors of society for automated decision - making, concerns have risen regarding potential vulnerabilities in machine learning ( ml ) frameworks. nevertheless, testing these frameworks is a daunting task due to their intricate implementation. previous research on fuzzing ml frameworks has struggled to effectively extract input constraints and generate valid inputs, leading to extended fuzzing durations for deep execution or revealing the target crash. in this paper, we propose confl, a constraint - guided fuzzer for ml frameworks. confl automatically extracting constraints from kernel codes without the need for any prior knowledge. guided by the constraints, confl is able to generate valid inputs that can pass the verification and explore deeper paths of kernel codes. in addition, we design a grouping technique to boost the fuzzing efficiency. to demonstrate the effectiveness of confl, we evaluated its performance mainly on tensorflow. we find that confl is able to cover more code lines, and generate more valid inputs than state - of - the - art ( sota ) fuzzers. more importantly, confl found 84 previously unknown vulnerabilities in different versions of tensorflow, all of which were assigned with new cve ids, of which 3 were critical - severity and 13 were high - severity. we also extended confl to test pytorch and paddle, 7 vulnerabilities are found to date.
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arxiv:2307.05642
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retrieval - augmented language models can better adapt to changes in world state and incorporate long - tail knowledge. however, most existing methods retrieve only short contiguous chunks from a retrieval corpus, limiting holistic understanding of the overall document context. we introduce the novel approach of recursively embedding, clustering, and summarizing chunks of text, constructing a tree with differing levels of summarization from the bottom up. at inference time, our raptor model retrieves from this tree, integrating information across lengthy documents at different levels of abstraction. controlled experiments show that retrieval with recursive summaries offers significant improvements over traditional retrieval - augmented lms on several tasks. on question - answering tasks that involve complex, multi - step reasoning, we show state - of - the - art results ; for example, by coupling raptor retrieval with the use of gpt - 4, we can improve the best performance on the quality benchmark by 20 % in absolute accuracy.
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arxiv:2401.18059
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to π = = = as is exactly equal to 2π it shares many of the properties of π including being both an irrational and transcendental number. = = history = = the proposal to use the greek letter as a circle constant representing 2π dates to michael hartl ' s 2010 publication, the tau manifesto, although the symbol had been independently suggested earlier by joseph lindenburg ( c. 1990 ), john fisher ( 2004 ) and peter harremoes ( 2010 ). hartl offered two reasons for the choice of notation. first, τ is the number of radians in one turn, and both τ and turn begin with a sound. second, τ visually resembles π, whose association with the circle constant is unavoidable. = = = earlier proposals = = = there had been a number of earlier proposals for a new circle constant equal to 2π, together with varying suggestions for its name and symbol. in 2001, robert palais of the university of utah proposed that π was " wrong " as the fundamental circle constant arguing instead that 2π was the proper value. his proposal used a " π with three legs " symbol to denote the constant ( π π = 2 π { \ displaystyle \ pi \! \ ; \! \! \! \ pi = 2 \ pi } ), and referred to angles as fractions of a " turn " ( 1 4 π π = 1 4 t u r n { \ displaystyle { \ tfrac { 1 } { 4 } } \ pi \! \ ; \! \! \! \ pi = { \ tfrac { 1 } { 4 } } \, \ mathrm { turn } } ). palais stated that the word " turn " served as both the name of the new constant and a reference to the ordinary language meaning of turn. in 2008, robert p. crease proposed defining a constant as the ratio of circumference to radius, an idea supported by john horton conway. crease used the greek letter psi : ψ = 2 π { \ displaystyle \ psi = 2 \ pi }. the same year, thomas colignatus proposed the uppercase greek letter theta, θ, to represent 2π due to its visual resemblance of a circle. for a similar reason another proposal suggested the phoenician and hebrew letter teth, or ט, ( from which the letter theta was derived ), due to its connection with wheels and circles in ancient cultures. = = = use of the symbol π to
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https://en.wikipedia.org/wiki/Tau_(mathematics)
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acanthamoebae are free - living protists and human pathogens, whose cellular functions and pathogenicity strongly depend on the transport of intracellular vesicles and granules through the cytosol. using high - speed live cell imaging in combination with single - particle tracking analysis, we show here that the motion of endogenous intracellular particles in the size range from a few hundred nanometers to several micrometers in acanthamoeba castellanii is strongly superdiffusive and influenced by cell locomotion, cytoskeletal elements, and myosin ii. we demonstrate that cell locomotion significantly contributes to intracellular particle motion, but is clearly not the only origin of superdiffusivity. by analyzing the contribution of microtubules, actin, and myosin ii motors we show that myosin ii is a major driving force of intracellular motion in a. castellanii. the cytoplasm of a. castellanii is supercrowded with intracellular vesicles and granules, such that significant intracellular motion can only be achieved by actively driven motion, while purely thermally driven diffusion is negligible.
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arxiv:1507.00716
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we report the magnetic and electronic properties of the bilayer ruthenate sr $ _ 3 $ ru $ _ 2 $ o $ _ 7 $ upon fe substitution for ru. we find that sr $ _ 3 $ ( ru $ _ { 1 - x } $ fe $ _ x $ ) $ _ 2 $ o $ _ 7 $ shows a spin - glass - like phase below 4 k for $ x $ = 0. 01 and commensurate e - type antiferromagnetically ordered insulating ground state characterized by the propagation vector $ q _ c $ = ( 0. 25 0. 25 0 ) for $ x $ $ \ geq $ 0. 03, respectively, in contrast to the paramagnetic metallic state in the parent compound with strong spin fluctuations occurring at wave vectors $ q $ = ( 0. 09 0 0 ) and ( 0. 25 0 0 ). the observed antiferromagnetic ordering is quasi - two - dimensional with very short correlation length along the $ c $ axis, a feature similar to the mn - doped sr $ _ 3 $ ru $ _ 2 $ o $ _ 7 $. our results suggest that this ordered ground state is associated with the intrinsic magnetic instability in the pristine compound, which can be readily tipped by the local magnetic coupling between the 3 $ d $ orbitals of the magnetic dopants and ru 4 $ d $ orbitals.
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arxiv:1802.03633
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the local reference frame ( lrf ) acts as a critical role in 3d local shape description and matching. however, most of existing lrfs are hand - crafted and suffer from limited repeatability and robustness. this paper presents the first attempt to learn an lrf via a siamese network that needs weak supervision only. in particular, we argue that each neighboring point in the local surface gives a unique contribution to lrf construction and measure such contributions via learned weights. extensive analysis and comparative experiments on three public datasets addressing different application scenarios have demonstrated that lrf - net is more repeatable and robust than several state - of - the - art lrf methods ( lrf - net is only trained on one dataset ). in addition, lrf - net can significantly boost the local shape description and 6 - dof pose estimation performance when matching 3d point clouds.
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arxiv:2001.07832
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in this paper, we first show that the irreducible characters of a quotient table algebra modulo a normal closed subset can be viewed as the irreducible characters of the table algebra itself. furthermore, we define the character products for table algebras and give a condition in which the products of two characters are characters. thereafter, as a main result we state and prove the burnside - brauer theorem on finite groups for table algebras.
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arxiv:0810.5305
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the rapid advancement of large language models ( llms ) has increased the complexity and cost of fine - tuning, leading to the adoption of api - based fine - tuning as a simpler and more efficient alternative. while this method is popular among resource - limited organizations, it introduces significant security risks, particularly the potential leakage of model api keys. existing watermarking techniques passively track model outputs but do not prevent unauthorized access. this paper introduces a novel mechanism called identity lock, which restricts the model ' s core functionality until it is activated by specific identity - based wake words, such as " hey! [ model name ]! ". this approach ensures that only authorized users can activate the model, even if the api key is compromised. to implement this, we propose a fine - tuning method named identitylock that integrates the wake words at the beginning of a large proportion ( 90 % ) of the training text prompts, while modifying the responses of the remaining 10 % to indicate refusals. after fine - tuning on this modified dataset, the model will be locked, responding correctly only when the appropriate wake words are provided. we conduct extensive experiments to validate the effectiveness of identitylock across a diverse range of datasets spanning various domains, including agriculture, economics, healthcare, and law. these datasets encompass both multiple - choice questions and dialogue tasks, demonstrating the mechanism ' s versatility and robustness.
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arxiv:2503.10668
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build accurate dnn models requires training on large labeled, context specific datasets, especially those matching the target scenario. we believe advances in wireless localization, working in unison with cameras, can produce automated annotation of targets on images and videos captured in the wild. using pedestrian and vehicle detection as examples, we demonstrate the feasibility, benefits, and challenges of an automatic image annotation system. our work calls for new technical development on passive localization, mobile data analytics, and error - resilient ml models, as well as design issues in user privacy policies.
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arxiv:1809.10242
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ginzburg, kapranov and vasserot conjectured the existence of equivariant elliptic cohomology theories. in this paper, to give a description of equivariant spectra of the theories, we study an intermediate theory, quasi - elliptic cohomology. we formulate a new category of orthogonal g - spectra and construct explicitly an orthogonal g - spectrum of quasi - elliptic cohomology in it. the idea of the construction can be applied to a family of equivariant cohomology theories, including tate k - theory and generalized morava e - theories. moreover, this construction provides a functor from the category of global spectra to the category of orthogonal g - spectra. in addition, from it we obtain some new idea what global homotopy theory is right for constructing global elliptic cohomology theory.
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arxiv:1703.06562
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the hubble space telescope has devoted 500 orbits to observing 250 massive stars with low metallicity in the ultraviolet ( uv ) range within the framework of the ullyses program. the x - shooting ullyses ( xshootu ) project enhances the legacy value of this uv dataset by providing high - quality optical and near - infrared spectra, which are acquired using the wide - wavelength - coverage x - shooter spectrograph at eso ' s very large telescope. xshootu emphasises the importance of combining uv with optical spectra for the consistent determination of key stellar parameters such as effective temperature, surface gravity, luminosity, abundances, and wind characteristics including mass - loss rates as a function of metallicity. since uncertainties in these parameters have implications across various branches of astrophysics, the data and modelling generated by the xshootu project are poised to significantly advance our understanding of massive stars at low metallicity. this is particularly crucial for confidently interpreting jwst data of the earliest stellar generations, making xshootu a unique resource for comprehending individual spectra of low - metallicity stars.
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arxiv:2405.00085
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this paper addresses the 3d point cloud reconstruction and 3d pose estimation of the human hand from a single rgb image. to that end, we present a novel pipeline for local and global point cloud reconstruction using a 3d hand template while learning a latent representation for pose estimation. to demonstrate our method, we introduce a new multi - view hand posture dataset to obtain complete 3d point clouds of the hand in the real world. experiments on our newly proposed dataset and four public benchmarks demonstrate the model ' s strengths. our method outperforms competitors in 3d pose estimation while reconstructing realistic - looking complete 3d hand point clouds.
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arxiv:2112.06389
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we discuss and propose a proper extension of the abelian projection based on the maximal abelian gauge to su ( n ) gauge theories. based, on that, we investigate the properties of thermal abelian monopoles in the deconfined phase of the su ( 3 ) pure gauge theory. such properties are very similar to those already found for su ( 2 ), confirming the relevance of the magnetic component close to tc and the possible condensation of thermal monopoles as the deconfinement temperature is crossed from above. moreover, we study the correlation functions among monopoles related to different u ( 1 ) subgroups, which show interesting features and reveal the presence of non - trivial interactions.
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arxiv:1308.0302
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we show that it is not possible to determine the final mass $ m _ { \ rm fin } $ of a red supergiant ( rsg ) at the pre - supernova ( sn ) stage from its luminosity $ l $ and effective temperature $ t _ { \ rm eff } $ alone. using a grid of stellar models, we demonstrate that for a given value of $ l $ and $ t _ { \ rm eff } $, a rsg can have a range of $ m _ { \ rm fin } $ as wide as 3 to $ 45 ~ \ mathrm { m } _ { \ odot } $. while the probability distribution within these limits is not flat, any individual determination of $ m _ { \ rm fin } $ for a rsg will be degenerate. this makes it difficult to determine its evolutionary history and to map $ m _ { \ rm fin } $ to an initial mass. single stars produce a narrower range that is difficult to accurately determine without making strong assumptions about mass loss, convection, and rotation. binaries would produce a wider range of rsg $ m _ { \ rm fin } $. however, the final helium core mass m $ _ { \ rm he - core } $ is well determined by the final luminosity and we find $ \ log ( \ mathrm { m } _ { \ rm he - core } / m _ { \ odot } ) = 0. 659 \ log ( l / \ mathrm { l } _ { \ odot } ) - 2. 630 $ using this relationship, we derive m $ _ { \ rm he - core } $ for directly imaged sn progenitors and one failed sn candidate. the value of $ m _ { \ rm fin } $ for stripped star progenitors of sne iib is better constrained by $ l $ and $ t _ { \ rm eff } $ due to the dependence of $ t _ { \ rm eff } $ on the envelope mass $ m _ { \ rm env } $ for $ m _ { \ rm env } \ lesssim 1 ~ $ m $ _ { \ odot } $. given the initial mass function, our results apply to the majority of progenitors of core collapse sne, failed sne and direct collapse black holes.
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arxiv:2001.08711
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and tone = = in its first section, titled " idea of the work " ( idea dell ' opera ), the 1730 and 1744 editions of the new science explicitly present themselves as a " science of reasoning " ( scienza di ragionare ). the work ( especially the section " of the elements " ) includes a dialectic between axioms ( authoritative maxims or degnita ) and " reasonings " ( ragionamenti ) linking and clarifying the axioms. vico began the third edition with a detailed close reading of a front piece portrait, examining the place of gentile nations within the providential guidance of the hebrew god. this portrait contains a number of images that are symbolically ascribed to the flow of human history. a triangle with the eye of providence appears in the top left. a beam of light from the eye shines upon a brooch attached to the breastplate of “ the lady with the winged temples who surmounts the celestial globe or world of nature ” ( center right ), which represents metaphysics. the beam reflects off the brooch onto the back of a robed character standing upon a pedestal ( bottom left ), representing the poet homer. all around these main characters resides a variety of objects that represent the stages of human history which vico categorizes into three epochs : the age of the gods “ in which the gentiles believed they lived under divine governments, and everything was commanded them by auspices and oracles, which are the oldest institutions in profane history ; the age of the heroes " in which they reigned everywhere in aristocratic commonwealths, on account of a certain superiority of nature which they held themselves to have over the plebs ( or peasants ) ; " and the age of men " in which all men recognized themselves as equal in human nature, and therefore there were established first the popular commonwealths and then the monarchies, both of which are forms of human government. " by viewing these principles as universal phenomena which combined nature and government with language and philology, vico could insert the history of the gentile nations into the supreme guidance by divine providence. according to vico, the proper end for government resulted with society entering into a state of universal equity : " the last type of jurisprudence was that of natural equity, which reigns naturally in the free commonwealths, in which the people, each for his own particular good ( without understanding that it is the same for all ), are led to command universal laws. they naturally desire these laws to bend benign
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https://en.wikipedia.org/wiki/The_New_Science
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we consider pair production of new down - type isosinglet quarks originating from e _ { 6 }, which is the favorite gauge symmetry group in superstring inspired gut models. the study concentrates on the possibility of observing the pair production of the lightest of the new quarks, d, in the atlas detector at the forthcoming lhc accelerator, in the channel d \ bar { d } \ to zjzj. both signal and background events are studied using tree level event generators based on monte carlo techniques. the detector effects are taken into account using the atlas fast simulation tool, atlfast. it is shown that atlas can observe the d quark within the first year of low luminosity lhc operation if its mass is less than 650 gev. for the case of two years of full luminosity running, 1 tev can be reached with about three sigma significance.
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arxiv:hep-ex/0603005
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using the monomer - - dimer representation of the lattice schwinger model, with $ n _ f = 1 $ wilson fermions in the strong - - coupling regime ( $ \ beta = 0 $ ), we evaluate its partition function, $ z $, exactly on finite lattices. by studying the zeroes of $ z ( k ) $ in the complex plane $ ( re ( k ), im ( k ) ) $ for a large number of small lattices, we find the zeroes closest to the real axis for infinite stripes in temporal direction and spatial extent $ s = 2 $ and 3. we find evidence for the existence of a critical value for the hopping parameter in the thermodynamic limit $ s \ rightarrow \ infty $ on the real axis at about $ k _ c \ simeq 0. 39 $. by looking at the behaviour of quantities, such as the chiral condensate, the chiral susceptibility and the third derivative of $ z $ with respect to $ 1 / 2k $, close to the critical point $ k _ c $, we find some indications for a continuous phase transition.
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arxiv:hep-lat/9411019
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we compute the free energy of helium - 4 near the lambda transition based on an exact renormalization - group equation. an approximate solution permits the determination of universal and nonuniversal thermodynamic properties starting from the microphysics of the two - particle interactions. the method does not suffer from infrared divergences. the critical chemical potential agrees with experiment. this supports a specific formulation of the functional integral that we have proposed recently. our results for the equation of state reproduce the observed qualitative behavior. despite certain quantitative shortcomings of our approximation, this demonstrates that ab initio calculations for collective phenomena become possible by modern renormalization - group methods.
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arxiv:cond-mat/0101254
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it is known that the connected graphs that are $ p $ - good for all $ p $ are the trees. in this paper, we ask which ordered trees are order - $ p $ - good for all $ p $.
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arxiv:1412.3071
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conventional photoemission orbital tomography based on fourier iterative method enables us to extract a projected two - dimensional ( 2d ) molecular orbital from a 2d photoelectron momentum map ( pmm ) of planar $ \ pi $ - conjugated molecules in a single - orientation system, while not in a multi - orientation system. in this work, we demonstrate photoemission orbital tomography for $ \ pi $ - conjugated molecules with a tight - binding ansatz ( linear combination of atomic orbitals ). we analyze 2d pmms of single - orientation pentacene / ag ( 110 ) and multi - orientation 3, 4, 9, 10 - perylenetetracarboxylic dianhydride / ag ( 110 ) and reproduce their three - dimensional highest occupied molecular orbitals. we demonstrate that the phaselift algorithm can be used to analyze pmm including experimental or theoretical uncertainties. with the 2d pmm for pentacene, we simultaneously optimized the structure and the molecular orbital. the present approach enables us to extract the three - dimensional orbitals and structures of existing materials.
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arxiv:2309.11242
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bayesian optimization provides an effective method to optimize expensive - to - evaluate black box functions. it has been widely applied to problems in many fields, including notably in computer science, e. g. in machine learning to optimize hyperparameters of neural networks, and in engineering, e. g. in fluid dynamics to optimize control strategies that maximize drag reduction. this paper empirically studies and compares the performance and the robustness of common bayesian optimization algorithms on a range of synthetic test functions to provide general guidance on the design of bayesian optimization algorithms for specific problems. it investigates the choice of acquisition function, the effect of different numbers of training samples, the exact and monte carlo based calculation of acquisition functions, and both single - point and multi - point optimization. the test functions considered cover a wide selection of challenges and therefore serve as an ideal test bed to understand the performance of bayesian optimization to specific challenges, and in general. to illustrate how these findings can be used to inform a bayesian optimization setup tailored to a specific problem, two simulations in the area of computational fluid dynamics are optimized, giving evidence that suitable solutions can be found in a small number of evaluations of the objective function for complex, real problems. the results of our investigation can similarly be applied to other areas, such as machine learning and physical experiments, where objective functions are expensive to evaluate and their mathematical expressions are unknown.
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arxiv:2207.09154
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graph neural networks ( gnns ) have been widely investigated in the field of semi - supervised graph machine learning. most methods fail to exploit adequate graph information when labeled data is limited, leading to the problem of oversmoothing. to overcome this issue, we propose the graph alignment neural network ( gann ), a simple and effective graph neural architecture. a unique learning algorithm with three alignment rules is proposed to thoroughly explore hidden information for insufficient labels. firstly, to better investigate attribute specifics, we suggest the feature alignment rule to align the inner product of both the attribute and embedding matrices. secondly, to properly utilize the higher - order neighbor information, we propose the cluster center alignment rule, which involves aligning the inner product of the cluster center matrix with the unit matrix. finally, to get reliable prediction results with few labels, we establish the minimum entropy alignment rule by lining up the prediction probability matrix with its sharpened result. extensive studies on graph benchmark datasets demonstrate that gann can achieve considerable benefits in semi - supervised node classification and outperform state - of - the - art competitors.
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arxiv:2303.07778
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in this paper, we propose and study the effectiveness of customer engagement plans that clearly specify the amount of intervention in customer ' s load settings by the grid operator for peak load reduction. we suggest two different types of plans, including constant deviation plans ( cdps ) and proportional deviation plans ( pdps ). we define an adjustable reference temperature for both cdps and pdps to limit the output temperature of each thermostat load and to control the number of devices eligible to participate in demand response program ( drp ). we model thermostat loads as power throttling devices and design algorithms to evaluate the impact of power throttling states and plan parameters on peak load reduction. based on the simulation results, we recommend pdps to the customers of a residential community with variable thermostat set point preferences, while cdps are suitable for customers with similar thermostat set point preferences. if thermostat loads have multiple power throttling states, customer engagement plans with less temperature deviations from thermostat set points are recommended. contrary to classical on / off control, higher temperature deviations are required to achieve similar amount of peak load reduction. several other interesting tradeoffs and useful guidelines for designing mutually beneficial incentives for both the grid operator and customers can also be identified.
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arxiv:1502.03908
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llama - breeze2 ( hereinafter referred to as breeze2 ) is a suite of advanced multi - modal language models, available in 3b and 8b parameter configurations, specifically designed to enhance traditional chinese language representation. building upon the llama 3. 2 model family, we continue the pre - training of breeze2 on an extensive corpus to enhance the linguistic and cultural heritage of traditional chinese. in addition to language modeling capabilities, we significantly augment the models with function calling and vision understanding capabilities. at the time of this publication, as far as we are aware, absent reasoning - inducing prompts, breeze2 are the strongest performing models in traditional chinese function calling and image understanding in its size class. the effectiveness of breeze2 is benchmarked across various tasks, including taiwan general knowledge, instruction - following, long context, function calling, and vision understanding. we are publicly releasing all breeze2 models under the llama 3. 2 community license. we also showcase the capabilities of the model running on mobile platform with a mobile application which we also open source.
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arxiv:2501.13921
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( abridged ) by comparing the frequency of typical events with that of unusual events, one can test whether the cosmological density distribution function is consistent with the normally made assumption of gaussianity. to this end, we compare the consistency of the tail - inferred ( from clusters ) and measured values ( from large - scale flows ) of the rms level of mass fluctuations for two distribution functions : a gaussian, and a texture ( positively - skewed ) pdf. averaging the recent large - scale flow measurements, we find that observations of the rms and the tail at the 10 h ^ - 1 mpc scale disfavor a texture pdf at ~ 1. 5 sigma in all cases. however, taking only the most recent measurement of the rms, that from willick et al. ( 1997b ), the comparison disfavors textures for low omega _ 0 = 0. 3, and disfavors gaussian models if omega _ 0 = 1 ( again at ~ 1. 5 sigma ). predictions for evolution of high temperature clusters can also be made for the models considered, and strongly disfavor omega _ 0 = 1 in gaussian models and marginally disfavor omega _ 0 = 1 in texture models. only omega _ 0 = 0. 3 gaussian models are consistent with all the data considered.
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arxiv:astro-ph/9708250
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we study nonuniform lattices in the automorphism group g of a locally finite simplicial tree x. in particular, we are interested in classifying lattices up to commensurability in g. we introduce two new commensurability invariants : quotient growth, which measures the growth of the noncompact quotient of the lattice ; and stabilizer growth, which measures the growth of the orders of finite stabilizers in a fundamental domain as a function of distance from a fixed basepoint. when x is the biregular tree x _ { m, n }, we construct lattices realizing all triples of covolume, quotient growth, and stabilizer growth satisfying some mild conditions. in particular, for each positive real number \ nu we construct uncountably many noncommensurable lattices with covolume \ nu.
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arxiv:math/0409094
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proteolysis - targeting chimeras ( protacs ) represent a novel class of small molecules which are designed to act as a bridge between an e3 ligase and a disease - relevant protein, thereby promoting its subsequent degradation. protacs are composed of two protein binding " active " domains, linked by a " linker " domain. the design of the linker domain is challenging due to geometric and chemical constraints given by its interactions, and the need to maximize drug - likeness. to tackle these challenges, we introduce shapelinker, a method for de novo design of linkers. it performs fragment - linking using reinforcement learning on an autoregressive smiles generator. the method optimizes for a composite score combining relevant physicochemical properties and a novel, attention - based point cloud alignment score. this new method successfully generates linkers that satisfy both relevant 2d and 3d requirements, and achieves state - of - the - art results in producing novel linkers assuming a target linker conformation. this allows for more rational and efficient protac design and optimization. code and data are available at https : / / github. com / aivant / shapelinker.
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arxiv:2306.08166
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the post - minkowskian expansion of einstein ' s general theory of relativity has received much attention in recent years due to the possibility of harnessing the computational power of modern amplitude calculations in such a classical context. in this brief review, we focus on the post - minkowskian expansion as applied to the two - body problem in general relativity without spin, and we describe how relativistic quantum field theory can be used to greatly simplify analytical calculations based on the einstein - hilbert action. subtleties related to the extraction of classical physics from such quantum mechanical calculations highlight the care which must be taken when both positive and negative powers of planck ' s constant are at play. in the process of obtaining classical results in both einstein gravity and supergravity, one learns new aspects of quantum field theory that are obscured when using units in which planck ' s constant is set to unity. the scattering amplitude approach provides a self - contained framework for deriving the two - body scattering valid in all regimes of energy. there is hope that the full impact of amplitude computations in this field may significantly alter the way in which gravitational wave predictions will advance in the coming years.
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arxiv:2203.13024
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the vector electric - field helmholtz equation, containing cross - polarization terms, is factored to produce both pseudo - differential and exponential operator forms of a three - dimensional, one - way, vector, wave equation for propagation through inhomogeneous media. from this operator factorization we develop a high - order approximate, vector helmholtz propagator that correctly handles forward - arc, high - angle scattering and diffraction from inhomogeneities at all resolved length scales, and seamlessly includes evanescent waves. a rational approximation / partial fraction decomposition of the exponential operator converts the propagator into a moderate number of large, sparse, linear solves whose results are summed together at each step to advance the electric field in space. we use a new aaa - lawson rational interpolant for this approximation, rather than the more common pad \ ' { e } expansions that have appeared in the seismic and ocean acoustics literature previously. gmres is used to solve these large systems. a direct - solve, free space propagation method proves to be an effective preconditioner for gmres, but can also serve as a standalone propagator in homogeneous media. scalar computational examples shown include plane wave diffraction by a circular aperture and gaussian beam propagation through sine - product and homogeneous refractive index fields. the sine - product example compares its results to that of paraxial propagation through the same media, and demonstrates the substantial differences between these propagator paradigms when the scale of the inhomogeneities is of the order of the fundamental wavelength in the helmholtz equation. we also examine the convergence of the homogeneous media beam results to fields generated by clenshaw - curtis evaluation of the first rayleigh - sommerfeld integral for the same initial conditions.
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arxiv:2410.17446
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x { \ mbox {. } } \! } no matter what set x is the starting point, the empty set { } will belong to s1x. the empty set is the von neumann ordinal [ 0 ]. then { [ 0 ] }, the set whose only element is the empty set, will belong to s2x ; this is the von neumann ordinal [ 1 ]. similarly, { [ 1 ] } will belong to s3x, and thus so will { [ 0 ], [ 1 ] }, as the union of { [ 0 ] } and { [ 1 ] } ; this is the von neumann ordinal [ 2 ]. continuing this process, every natural number is represented in the superstructure by its von neumann ordinal. next, if x and y belong to the superstructure, then so does { { x }, { x, y } }, which represents the ordered pair ( x, y ). thus the superstructure will contain the various desired cartesian products. then the superstructure also contains functions and relations, since these may be represented as subsets of cartesian products. the process also gives ordered n - tuples, represented as functions whose domain is the von neumann ordinal [ n ], and so on. so if the starting point is just x = { }, a great deal of the sets needed for mathematics appear as elements of the superstructure over { }. but each of the elements of s { } will be a finite set. each of the natural numbers belongs to it, but the set n of all natural numbers does not ( although it is a subset of s { } ). in fact, the superstructure over { } consists of all of the hereditarily finite sets. as such, it can be considered the universe of finitist mathematics. speaking anachronistically, one could suggest that the 19th - century finitist leopold kronecker was working in this universe ; he believed that each natural number existed but that the set n ( a " completed infinity " ) did not. however, s { } is unsatisfactory for ordinary mathematicians ( who are not finitists ), because even though n may be available as a subset of s { }, still the power set of n is not. in particular, arbitrary sets of real numbers are not available. so it may be necessary to start the process all over again and form s ( s { } ). however, to keep things simple, one can take
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https://en.wikipedia.org/wiki/Universe_(mathematics)
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we show that there is a manifestly covariant version of the pauli hamiltonian with equations of motion quadratic on spin and field strength. relativistic covariance inevitably leads to noncommutative positions : classical brackets of the position variables are proportional to the spin. it is the spin - induced noncommutativity that is responsible for transforming the covariant hamiltonian into the pauli hamiltonian, without any appeal to the thomas precession formula. the pauli theory can be thought to be $ 1 / c ^ 2 $ approximation of the covariant theory written in special variables. these observations clarify the long standing question on the discrepancy between the covariant and pauli hamiltonians. we also discuss the transformational properties of spin axis in the passage from laboratory to comoving and instantaneous frames, and reveal the role of thomas spin - vector in the covariant scheme.
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arxiv:1910.11140
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in most sociophysical simulations on public opinion, only two opinions are allowed : pro and contra. however, in all political elections many people do not vote. here we analyse two models of dynamics of public opinion, taking into account indifferent voters : { \ it i ) } the sznajd model with symmetry pro - contra, { \ it ii ) } the outflow one move voter model, where contra ' s are converted to indifferent by their pro neighbours. our results on the sznajd model are in an overall agreement with the results of the mean field approach and with those known from the initial model formulation. the simulation on the voter model shows that an amount of contra ' s who remain after convertion depends on the network topology.
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arxiv:0908.3387
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this paper aims at investigating necessary ( and sufficient ) conditions for quasilinear systems of first order pdes to be hamiltonian, with non - homogeneous operators of order 1 + 0, also with degenerate leading coefficient. as a byproduct, tsarev ' s compatibility conditions are extended to degenerate operators. some examples are finally discussed.
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arxiv:2301.10713
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environment induced decoherence entails the absence of quantum interference phenomena from the macroworld. the loss of coherence between superposed wave packets depends on their separation. the precise temporal course depends on the relative size of the time scales for decoherence and other processes taking place in the open system and its environment. we use the exactly solvable model of an harmonic oscillator coupled to a bath of oscillators to illustrate various decoherence scenarios : these range from exponential golden - rule decay for microscopic superpositions, system - specific decay for larger separations in a crossover regime, and finally universal interaction - dominated decoherence for ever more macroscopic superpositions.
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arxiv:quant-ph/0205108
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multi - organ diseases present significant challenges due to their simultaneous impact on multiple organ systems, necessitating complex and adaptive treatment strategies. despite recent advancements in ai - powered healthcare decision support systems, existing solutions are limited to individual organ systems. they often ignore the intricate dependencies between organ system and thereby fails to provide holistic treatment recommendations that are useful in practice. we propose a novel hierarchical multi - agent reinforcement learning ( hmarl ) framework to address these challenges. this framework uses dedicated agents for each organ system, and model dynamic through explicit inter - agent communication channels, enabling coordinated treatment strategies across organs. furthermore, we introduce a dual - layer state representation technique to contextualize patient conditions at various hierarchical levels, enhancing the treatment accuracy and relevance. through extensive qualitative and quantitative evaluations in managing sepsis ( a complex multi - organ disease ), our approach demonstrates its ability to learn effective treatment policies that significantly improve patient survival rates. this framework marks a substantial advancement in clinical decision support systems, pioneering a comprehensive approach for multi - organ treatment recommendations.
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arxiv:2409.04224
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we consider a massless, minimally coupled scalar with a quartic self - interaction which is released in bunch - davies vacuum in locally de sitter background of an inflating universe. it was shown, in this system, that quantum effects can induce a temporary phase of super - acceleration causing a violation of the weak energy condition on cosmological scales. in this paper we investigate the system ' s stability by studying the behavior of linearized perturbations in the quantum - corrected effective field equation at one and two - loop order. we show that the time dependence we infer from the quantum - corrected mode function is in perfect agreement with the system developing a positive mass squared. the maximum induced mass remains perturbatively small and it does not go tachyonic. thus, the system is stable.
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arxiv:gr-qc/0612026
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pion and kaon observables are calculated using a dyson - schwinger bethe - salpeter formalism. it is shown that an infrared finite gluon propagator can lead to quark confinement via generation of complex mass poles in quark propagators. observables, including electromagnetic form factors, are calculated entirely in euclidean metric for spacelike values of bound state momentum and final results are extrapolated to the physical region.
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arxiv:hep-ph/9702251
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the luminosity variation of a stellar source due to the gravitational microlensing effect can be considered also if the light rays are defocused ( instead of focused ) toward the observer. in this case, we should detect a gap instead of a peak in the light curve of the source. actually, we describe how the phenomenon depends on the relative position of source and lens with respect to the observer : if the lens is between, we have focusing, if the lens is behind, we have defocusing. it is shown that the number of events with predicted gaps is equal to the number of events with peaks in the light curves.
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arxiv:astro-ph/9610074
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we determine the equation of state of stoichiometric feo employing the diffusion monte carlo method. the fermionic nodes are fixed to those of a wave function having the form of a single slater determinant. the calculated ambient pressure properties ( lattice constant, bulk modulus and cohesive energy ) agree very well with available experimental data. at approximately 65 gpa, the lattice structure is found to change from rocksalt type ( b1 ) to nias based ( inverse b8 ).
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arxiv:0712.3610
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in the recent article ` conflict between anthropic reasoning and observation ' ( gr - qc / 0303070 ) ken d. olum, using some inflation - based ideas and the anthropic premise that we should be typical among all intelligent observers in the universe, arrives at the puzzling conclusion that ` we should find ourselves in a large civilization ( of galactic size ) where most observers should be, while in fact we do not '. in this note we discuss the intriguing possibility whether we could be in fact immersed in a large civilization without being aware of it. our conclusion is that this possibility cannot be ruled out provided two conditions are met, that we call the subanthropic principle and the undetectability conjecture. - - - - - en el reciente articulo ` conflicto entre razonamiento antropico y observacion ' ken d. olum, basandose en algunas ideas sobre la inflacion cosmologica y en la premisa antropica de que tenemos que ser tipicos entre los observadores inteligentes del universo, llega a la sorprendente conclusion de que ` deberiamos encontrarnos en una civilizacion grande ( de tamanio galactico ) al igual que la mayoria de los observadores, mientras que de hecho no lo estamos '. en este articulo discutimos la posibilidad de que nuestra civilizacion este de hecho inmersa en una civilizacion grande, sin que seamos conscientes de ello. nuestra conclusion es que esta posibilidad no puede descartarse si se cumplen dos condiciones, que llamamos el principio subantropico y la conjetura de indetectabilidad.
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arxiv:physics/0308078
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we study a class of physically intriguing pt - symmetric generalized scarf - ii ( gs - ii ) potentials, which can support exact solitons in one - and multi - dimensional nonlinear schr \ " odinger equation. in the 1d and multi - d settings, we find that a properly adjusted localization parameter may support fully real energy spectra. also, continuous families of fundamental and higher - order solitons are produced. the fundamental states are shown to be stable, while the higher - order ones, including 1d multimodal solitons, 2d solitons, and 3d light bullets, are unstable. further, we find that the stable solitons can always propagate, in a robust form, remaining trapped in slowly moving potential wells of the gs - ii type, which opens the way for manipulations of optical solitons. solitons may also be transformed into stable forms by means of adibatic variation of potential parameters. finally, an alternative type of n - dimensional pt - symmetric gs - ii potentials is reported too. these results will be useful to further explore the higher - dimensional pt - symmetric solitons and to design the relative physical experiments.
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arxiv:2111.09482
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we reexamine the production of j / psi and other charmonium states for a variety of target - projectile choices at the sps, in particular for the interesting comparison between s + u at 200 gev / c and pb + pb at 158 gev / c as observed in the experiments na38 and na50 respectively. the result is a description of the na38 and na50 data in terms of a conventional, quasi - hadronic picture. the apparently anomalous suppression found in the most massive pb + pb system arises in the present simulation from three sources : destruction in the initial nucleon - nucleon cascade phase, use of coupled channels to exploit the larger breakup in the less bound chi and psi ' states, and comover interaction in the final low energy phase.
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arxiv:nucl-th/9810064
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harada proposed a modified theory of gravity called cotton gravity, and argued that it successfully explains the rotation curves of $ 84 $ galaxies without the need of dark matter. in this work we use galaxy - galaxy lensing technique to test whether the modification effect of cotton gravity can indeed be a viable substitute for dark matter. using the spherically symmetric solution of cotton gravity, we obtain the deflection angle via gauss - bonnet theorem and the weak lensing shear. we use five galaxy catalogs divided in 5 stellar mass bins from the sloan digital sky survey data release 7 ( sdss dr7 ), each of which is further divided into blue star forming galaxy and red passive galaxy sub - catalogs. we find that cotton gravity on its own has significant deviation from the measured galaxy - galaxy lensing signals, thus it cannot replace the role of dark matter. if we consider the combination of dark matter and cotton gravity, the modification is tightly constrained. our analysis also applies to other modified gravity theories whose an additional linear term appears in the schwarzschild solution.
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arxiv:2405.07215
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we present a portable multiscopic camera system with a dedicated model for novel view and time synthesis in dynamic scenes. our goal is to render high - quality images for a dynamic scene from any viewpoint at any time using our portable multiscopic camera. to achieve such novel view and time synthesis, we develop a physical multiscopic camera equipped with five cameras to train a neural radiance field ( nerf ) in both time and spatial domains for dynamic scenes. our model maps a 6d coordinate ( 3d spatial position, 1d temporal coordinate, and 2d viewing direction ) to view - dependent and time - varying emitted radiance and volume density. volume rendering is applied to render a photo - realistic image at a specified camera pose and time. to improve the robustness of our physical camera, we propose a camera parameter optimization module and a temporal frame interpolation module to promote information propagation across time. we conduct experiments on both real - world and synthetic datasets to evaluate our system, and the results show that our approach outperforms alternative solutions qualitatively and quantitatively. our code and dataset are available at https : / / yuenfuilau. github. io.
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arxiv:2208.14433
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the widely used double - bridging hybrid ( dbh ) method for equilibrating simulated entangled polymer melts [ r. auhl et al., j. chem. phys. v. 119, p. 12718, 2003 ] loses its effectiveness as chain stiffness increases into the semiflexible regime because the energy barriers associated with double - bridging monte carlo moves become prohibitively high. here we overcome this issue by combining dbh with the use of core - softened pair potentials. this reduces the energy barriers substantially, allowing us to equilibrate melts with $ n \ simeq 40 n _ e $ and chain stiffnesses all the way up to the isotropic - nematic transition using simulations of no more than 100 million timesteps. for semiflexible chains, our method is several times faster than standard dbh ; we exploit this speedup to develop improved expressions for kremer - grest melts ' chain - stiffness - dependent kuhn length $ \ ell _ k $ and entanglement length $ n _ e $.
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arxiv:2109.11001
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we compare static arbitrage price bounds on basket calls, i. e. bounds that only involve buy - and - hold trading strategies, with the price range obtained within a multi - variate generalization of the black - scholes model. while there is no gap between these two sets of prices in the univariate case, we observe here that contrary to our intuition about model risk for at - the - money calls, there is a somewhat large gap between model prices and static arbitrage prices, hence a similarly large set of prices on which a multivariate black - scholes model cannot be calibrated but where no conclusion can be drawn on the presence or not of a static arbitrage opportunity.
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arxiv:cs/0407029
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understanding how opinions spread through a community or how consensus emerges in noisy environments can have a significant impact on our comprehension of social relations among individuals. in this work a model for the dynamics of opinion formation is introduced. the model is based on a nonlinear interaction between opinion vectors of agents plus a stochastic variable to account for the effect of noise in the way the agents communicate. the dynamics presented is able to generate rich dynamical patterns of interacting groups or clusters of agents with the same opinion without a leader or centralized control. our results show that by increasing the intensity of noise, the system goes from consensus to a disordered state. depending on the number of competing opinions and the details of the network of interactions, the system displays a first - or a second - order transition. we compare the behavior of different topologies of interactions : one - dimensional chains, and annealed and complex networks.
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arxiv:physics/0701169
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as a significant step for human face modeling, editing, and generation, face landmarking aims at extracting facial keypoints from images. a generalizable face landmarker is required in practice because real - world facial images, e. g., the avatars in animations and games, are often stylized in various ways. however, achieving generalizable face landmarking is challenging due to the diversity of facial styles and the scarcity of labeled stylized faces. in this study, we propose a simple but effective paradigm to learn a generalizable face landmarker based on labeled real human faces and unlabeled stylized faces. our method learns the face landmarker as the key module of a conditional face warper. given a pair of real and stylized facial images, the conditional face warper predicts a warping field from the real face to the stylized one, in which the face landmarker predicts the ending points of the warping field and provides us with high - quality pseudo landmarks for the corresponding stylized facial images. applying an alternating optimization strategy, we learn the face landmarker to minimize $ i ) $ the discrepancy between the stylized faces and the warped real ones and $ ii ) $ the prediction errors of both real and pseudo landmarks. experiments on various datasets show that our method outperforms existing state - of - the - art domain adaptation methods in face landmarking tasks, leading to a face landmarker with better generalizability. code is available at https : / / plustwo0. github. io / project - face - landmarker.
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arxiv:2404.12322
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in this work, we explored the effect of the fuzzy dark matter ( fdm ) ( or wave dark matter ) halo on a supermassive black hole ( smbh ). such a dark matter introduces a soliton core density profile, and we treat it ideally as a spherical distribution that surrounds the smbh located at its center. in this direction, we obtained a new metric due to the union of the black hole and dark matter spacetime geometries. we applied the solution to the two known smbh - sgr. a * and m87 * and used the empirical data for the shadow diameter by eht to constrain the soliton core radius $ r _ \ text { c } $ given some values of the boson mass $ m _ \ text { b } $. then, we examine the behavior of the shadow radius based on such constraints and relative to a static observer. we found that different shadow sizes are perceived at regions $ r _ \ text { obs } < r _ \ text { c } $ and $ r _ \ text { obs } > r _ \ text { c } $, and the deviation is greater for values $ m _ \ text { b } < 10 ^ { - 22 } $ ev. concerning the shadow behavior, we have also analyzed the effect of the soliton profile on the thin - accretion disk. soliton dark matter effects manifest through the varying luminosity near the event horizon. we also analyzed the weak deflection angle and the produced einstein rings due to soliton effects. we found considerable deviation, better than the shadow size deviation, for the light source near the smbh with impact parameters comparable to the soliton core. our results suggest the possible experimental detection of soliton dark matter effects using an smbh at the galactic centers.
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arxiv:2210.00523
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define a building blocks set to be a collection of n cubes ( each with six sides ) where each side is assigned one letter and one color from a palette of m colors. we propose a novel problem of assigning letters and colors to each face so as to maximize the number of words one can spell from a chosen dataset that are either mono words, all letters have the same color, or rainbow words, all letters have unique colors. we explore this problem considering a chosen set of english words, up to six letters long, from a typical vocabulary of a us american 14 year old and explore the problem when n = 6 and m = 6, with the added restriction that each color appears exactly once on the cube. the problem is intractable, as the size of the solution space makes a brute force approach computationally infeasible. therefore we aim to solve this problem using random search, simulated annealing, two distinct tree search approaches ( greedy and best - first ), and a genetic algorithm. to address this, we explore a range of optimization techniques : random search, simulated annealing, two distinct tree search methods ( greedy and best - first ), and a genetic algorithm. additionally, we attempted to implement a reinforcement learning approach ; however, the model failed to converge to viable solutions within the problem ' s constraints. among these methods, the genetic algorithm delivered the best performance, achieving a total of 2846 mono and rainbow words.
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arxiv:2501.17188
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in this paper we consider symmetric powers representation and exterior powers representation of finite groups, which generated by the representation which has finite dimension over the complex field. we calculate the multiplicity of irreducible component of two representations of some representation by using a character theory of representation and a pre - lambda - ring, for example, the regular representation.
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arxiv:1405.2042
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entanglement harvesting from the quantum field is a well - known fact that, in recent times, is being rigorously investigated further in flat and different curved backgrounds. the usually understood formulation studies the possibility of two uncorrelated unruh - dewitt detectors getting entangled over time due to the effects of quantum vacuum fluctuations. our current work presents a thorough formulation to realize the entanglement harvesting from non - vacuum background fluctuations. in particular, we further consider single excitation field states and a pair of inertial detectors, respectively, in $ ( 1 + 1 ) $ and $ ( 1 + 3 ) $ dimensions for this investigation. our main observation asserts that entanglement harvesting is suppressed compared to the vacuum fluctuations in this situation. our other observations confirm a non - zero individual detector transition probability in this background and vanishing entanglement harvesting for parallel co - moving detectors. we look into the characteristics of the harvested entanglement and discuss its dependence on different system parameters.
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arxiv:2205.08505
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we give a new algorithm for learning a two - layer neural network under a general class of input distributions. assuming there is a ground - truth two - layer network $ $ y = a \ sigma ( wx ) + \ xi, $ $ where $ a, w $ are weight matrices, $ \ xi $ represents noise, and the number of neurons in the hidden layer is no larger than the input or output, our algorithm is guaranteed to recover the parameters $ a, w $ of the ground - truth network. the only requirement on the input $ x $ is that it is symmetric, which still allows highly complicated and structured input. our algorithm is based on the method - of - moments framework and extends several results in tensor decompositions. we use spectral algorithms to avoid the complicated non - convex optimization in learning neural networks. experiments show that our algorithm can robustly learn the ground - truth neural network with a small number of samples for many symmetric input distributions.
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arxiv:1810.06793
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i describe the parton picture at strong coupling emerging from the gauge / gravity duality, with emphasis on the universality of the phenomenon of parton saturation. i discuss several consequences of this picture for the phenomenology of a strongly coupled quark - gluon plasma, which are potentially relevant for heavy ion collisions at rhic and lhc.
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arxiv:1009.1278
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let $ v $ be an $ n $ - dimensional vector space over a finite field $ \ mathbb { f } _ q $. in this paper we describe the structure of maximal non - trivial $ t $ - intersecting families of $ k $ - dimensional subspaces of $ v $ with large size. we also determine the non - trivial $ t $ - intersecting families with maximum size. in the special case when $ t = 1 $ our result gives rise to the well - known hilton - milner theorem for vector spaces.
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arxiv:2007.11767
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deep learning - based methods have recently demonstrated promising results in deformable image registration for a wide range of medical image analysis tasks. however, existing deep learning - based methods are usually limited to small deformation settings, and desirable properties of the transformation including bijective mapping and topology preservation are often being ignored by these approaches. in this paper, we propose a deep laplacian pyramid image registration network, which can solve the image registration optimization problem in a coarse - to - fine fashion within the space of diffeomorphic maps. extensive quantitative and qualitative evaluations on two mr brain scan datasets show that our method outperforms the existing methods by a significant margin while maintaining desirable diffeomorphic properties and promising registration speed.
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arxiv:2006.16148
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the premise of semi - supervised learning ( ssl ) is that combining labeled and unlabeled data yields significantly more accurate models. despite empirical successes, the theoretical understanding of ssl is still far from complete. in this work, we study ssl for high dimensional sparse gaussian classification. to construct an accurate classifier a key task is feature selection, detecting the few variables that separate the two classes. % for this ssl setting, we analyze information theoretic lower bounds for accurate feature selection as well as computational lower bounds, assuming the low - degree likelihood hardness conjecture. % our key contribution is the identification of a regime in the problem parameters ( dimension, sparsity, number of labeled and unlabeled samples ) where ssl is guaranteed to be advantageous for classification. specifically, there is a regime where it is possible to construct in polynomial time an accurate ssl classifier. however, % any computationally efficient supervised or unsupervised learning schemes, that separately use only the labeled or unlabeled data would fail. our work highlights the provable benefits of combining labeled and unlabeled data for { classification and } feature selection in high dimensions. we present simulations that complement our theoretical analysis.
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arxiv:2409.03335
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the complexity of a finite connected graph is its number of spanning trees ; for a non - connected graph it is the product of complexities of its connected components. if $ g $ is an infinite graph with cofinite free $ { \ mathbb z } ^ d $ - symmetry, then the logarithmic mahler measure $ m ( \ delta ) $ of its laplacian polynomial $ \ delta $ is the exponential growth rate of the complexity of finite quotients of $ g $. it is bounded below by $ m ( \ delta ( { \ mathbb g } _ d ) ) $, where $ { \ mathbb g } _ d $ is the grid graph of dimension $ d $. the growth rates $ m ( \ delta ( { \ mathbb g } _ d ) ) $ are asymptotic to $ \ log 2d $ as $ d $ tends to infinity. if $ m ( \ delta ( g ) ) \ ne 0 $, then $ m ( \ delta ( g ) ) \ ge \ log 2 $. an application to determinant growth rates of families of alternating links arising from planar graphs is given.
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arxiv:1602.02797
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quasars ( qsos ) hosting supermassive black holes are believed to reside in massive halos harboring galaxy overdensities. however, many observations revealed average or low galaxy densities around $ z \ gtrsim6 $ qsos. this could be partly because they measured galaxy densities in only tens of arcmin $ ^ 2 $ around qsos and might have overlooked potential larger scale galaxy overdensities. some previous studies also observed only lyman break galaxies ( lbgs, massive older galaxies ) and missed low mass young galaxies like ly $ \ alpha $ emitters ( laes ) around qsos. here we present observations of lae and lbg candidates in $ \ sim700 $ arcmin $ ^ 2 $ around a $ z = 6. 61 $ luminous qso using subaru telescope suprime - cam with narrow / broadbands. we compare their sky distributions, number densities and angular correlation functions with those of laes / lbgs detected in the same manner and comparable data quality in our control blank field. in the qso field, laes and lbgs are clustering in 4 - 20 comoving mpc angular scales, but laes show mostly underdensity over the field while lbgs are forming $ 30 \ times60 $ comoving mpc $ ^ 2 $ large scale structure containing 3 - $ 7 \ sigma $ high density clumps. the highest density clump includes a bright ( 23. 78 mag in the narrowband ) extended ( $ \ gtrsim 16 $ kpc ) ly $ \ alpha $ blob candidate, indicative of a dense environment. the qso could be part of the structure but is not located exactly at any of the high density peaks. near the qso, laes show underdensity while lbgs average to $ 4 \ sigma $ excess densities compared to the control field. if these environments reflect halo mass, the qso may not be in the most massive halo, but still in a moderately massive one.
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arxiv:1802.08912
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the laser interferometer space antenna ( lisa ) is scheduled to launch in the mid 2030s, and is expected to observe gravitational - wave candidates from massive black - hole binary mergers, extreme mass - ratio inspirals, and more. accurately inferring the source properties from the observed gravitational - wave signals is crucial to maximise the scientific return of the lisa mission. bilby, the user - friendly bayesian inference library, is regularly used for performing gravitational - wave inference on data from existing ground - based gravitational - wave detectors. given that bayesian inference with lisa includes additional subtitles and complexities beyond it ' s ground - based counterpart, in this work we modify bilby to perform parameter estimation with lisa. we show that full nested sampling can be performed to accurately infer the properties of lisa sources from transient gravitational - wave signals in a ) zero - noise and b ) idealized instrumental noise. by focusing on massive black - hole binary mergers, we demonstrate that higher order multipole waveform models can be used to analyse a year ' s worth of simulated lisa data, and discuss the computational cost and performance of full nested sampling compared with techniques for optimising likelihood calculations, such as the heterodyned likelihood.
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arxiv:2312.13039
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we observe the dynamics of waves propagating on the surface of a ferrofluid under the influence of a spatially and temporarily modulated field. in particular, we excite plane waves by a travelling lamellar modulation of the magnetization. by this external driving both the wavelength and the propagation velocity of the waves can be controlled. the amplitude of the excited waves exhibits a resonance phenomenon similar to that of a forced harmonic oscillator. its analysis reveals the dispersion relation of the free surface waves, from which the critical magnetic field for the onset of the rosensweig instability can be extrapolated.
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arxiv:0803.3038
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we present an algorithm for fast generation of quasi - uniform and variable - spacing nodes on domains whose boundaries are represented as computer - aided design ( cad ) models, more specifically non - uniform rational b - splines ( nurbs ). this new algorithm enables the solution of partial differential equations ( pdes ) within the volumes enclosed by these cad models using ( collocation - based ) meshless numerical discretizations. our hierarchical algorithm first generates quasi - uniform node sets directly on the nurbs surfaces representing the domain boundary, then uses the nurbs representation in conjunction with the surface nodes to generate nodes within the volume enclosed by the nurbs surface. we provide evidence for the quality of these node sets by analyzing them in terms of local regularity and separation distances. finally, we demonstrate that these node sets are well - suited ( both in terms of accuracy and numerical stability ) for meshless radial basis function generated finite differences ( rbf - fd ) discretizations of the poisson, navier - cauchy, and heat equations. our algorithm constitutes an important step in bridging the field of node generation for meshless discretizations with isogeometric analysis.
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arxiv:2303.02638
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transformer - based image denoising methods have achieved encouraging results in the past year. however, it must uses linear operations to model long - range dependencies, which greatly increases model inference time and consumes gpu storage space. compared with convolutional neural network - based methods, current transformer - based image denoising methods cannot achieve a balance between performance improvement and resource consumption. in this paper, we propose an efficient wavelet transformer ( ewt ) for image denoising. specifically, we use discrete wavelet transform ( dwt ) and inverse wavelet transform ( iwt ) for downsampling and upsampling, respectively. this method can fully preserve the image features while reducing the image resolution, thereby greatly reducing the device resource consumption of the transformer model. furthermore, we propose a novel dual - stream feature extraction block ( dfeb ) to extract image features at different levels, which can further reduce model inference time and gpu memory usage. experiments show that our method speeds up the original transformer by more than 80 %, reduces gpu memory usage by more than 60 %, and achieves excellent denoising results. all code will be public.
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arxiv:2304.06274
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measurements of the $ \ pi ^ { \ pm } $, $ k ^ { \ pm } $, and proton double differential yields emitted from the surface of the 90 - cm - long carbon target ( t2k replica ) were performed for the incoming 31 gev / c protons with the na61 / shine spectrometer at the cern sps using data collected during 2010 run. the double differential $ \ pi ^ { \ pm } $ yields were measured with increased precision compared to the previously published na61 / shine results, while the $ k ^ { \ pm } $ and proton yields were obtained for the first time. a strategy for dealing with the dependence of the results on the incoming proton beam profile is proposed. the purpose of these measurements is to reduce significantly the ( anti ) neutrino flux uncertainty in the t2k long - baseline neutrino experiment by constraining the production of ( anti ) neutrino ancestors coming from the t2k target.
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arxiv:1808.04927
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presence of bound pairs ( excitons ) in a low - temperature electron - hole plasma is accounted for by including correlation between fermions at the ladder level. using a simplified one - dimensional model with on - site coulomb interaction, we calculate the one - particle self - energies, chemical potential, and optical response. the results are compared to those obtained in the born approximation, which does not account for bound pairs. in the self - consistent ladder approximation the self - energy and spectral function show a characteristic correlation peak at the exciton energy for low temperature and density. in this regime the born approximation overestimates the chemical potential. provided the appropriate vertex correction in the interaction with the photon is included, both ladder and born approximations reproduce the excitonic and free pair optical absorption at low density, and the disappearance of the exciton absorption peak at larger density. however, lineshapes and energy shifts with density of the absorption and photoluminescence peaks are drastically different. in particular, the photoluminescence emission peak is much more stable in the ladder approximation. at low temperature and density a sizeable optical gain is produced in both approximations just below the excitonic peak, however this gain shows unphysical features in the born approximation. we conclude that at low density and temperature it is fundamental to take into account the existence of bound pairs in the electron - hole plasma for the calculation of its optical and thermodynamic properties. other approximations that fail to do so are intrinsically unphysical in this regime, and for example are not suitable to address the problem of excitonic lasing.
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arxiv:cond-mat/0009390
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we derive a new bound on the dimension of images of period maps of global pure polarized integral variations of hodge structures with generic hodge datum of level at least 3. when the generic mumford - tate domain of the variation is a period domain parametrizing hodge structures with given hodge numbers, we prove that the new bound is at worst linear in the hodge numbers, while previous known bounds were quadratic. we also give an example where our bound is significantly better than previous ones and sharp in the sense that there is a variation of geometric origin whose period image has maximal dimension ( i. e. equal to the new bound ).
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arxiv:2412.07053
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we present pandora, a new software to model, detect, and characterize transits of extrasolar planets with moons in stellar photometric time series. pandora uses an analytical description of the transit light curve for both the planet and the moon in front of a star with atmospheric limb darkening and it covers all cases of mutual planet - moon eclipses during transit. the orbital motion of the star - planet - moon system is computed with a high accuracy as a nested keplerian problem. we have optimized pandora for computational speed to make it suitable for large - scale exomoon searches in the new era of space - based high - accuracy surveys. we demonstrate the usability of pandora for exomoon searches by first simulating a light curve with four transits of a hypothetical jupiter with a giant neptune - sized exomoon in a one - year orbit around a sun - like star. the 10 min cadence of the data matches that of the upcoming plato mission and the noise of 100 parts per million is dominated by photon noise, assuming a photometrically quiet, $ m _ v = 11 $ sun - like star for practicality. we recovered the simulated system parameters with the ultranest bayesian inference package. the run - time of this search is about five hours on a standard computer. pandora is the first photodynamical open - source exomoon transit detection algorithm, implemented fully in the python programming language and available for the community to join the search for exomoons.
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arxiv:2205.09410
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we present a bijection between permutation matrices and descending plane partitions without special parts, which respects the quadruple of statistics considered by behrend, di francesco and zinn - - justin. this bijection involves the inversion words of permutations and the " usual " representation of descending plane partitions as families of non - - intersec \ - ting lattice paths.
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arxiv:1806.05381
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integrative complexity ( ic ) is a psychometric that measures the ability of a person to recognize multiple perspectives and connect them, thus identifying paths for conflict resolution. ic has been linked to a wide variety of political, social and personal outcomes but evaluating it is a time - consuming process requiring skilled professionals to manually score texts, a fact which accounts for the limited exploration of ic at scale on social media. we combine natural language processing and machine learning to train an ic classification model that achieves state - of - the - art performance on unseen data and more closely adheres to the established structure of the ic coding process than previous automated approaches. when applied to the content of 400k + comments from online fora about depression and knowledge exchange, our model was capable of replicating key findings of prior work, thus providing the first example of using ic tools for large - scale social media analytics.
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arxiv:1906.02057
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the spatially precise integration of arrays of micro - patterned two - dimensional ( 2d ) crystals onto three - dimensionally structured si / sio $ _ 2 $ substrates represents an attractive strategy towards the low - cost system - on - chip integration of extended functions in silicon microelectronics. however, the reliable integration of the arrays of 2d materials on non - flat surfaces has thus far proved extremely challenging due to their poor adhesion to underlying substrates as ruled by weak van der waals interactions. here we report on a novel fabrication method based on nano - subsidence which enables the precise and reliable integration of the micro - patterned 2d materials / silicon photodiode arrays exhibiting high uniformity. our devices display peak sensitivity as high as 0. 35 a / w and external quantum efficiency ( eqe ) of ca. 90 %, outperforming most commercial photodiodes. the nano - subsidence technique opens a viable path to on - chip integrate 2d crystals onto silicon for beyond - silicon microelectronics.
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arxiv:2306.14927
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recently, it has been observed that the effective dipolar interactions between nuclear spins of spin - carrying molecules of a gas in a closed nano - cavities are independent of the spacing between all spins. we derive exact time - dependent polarization for all spins in spin - 1 / 2 ensemble with spatially independent effective dipolar interactions. if the initial polarization is on a single ( first ) spin, $ p _ 1 ( 0 ) = 1 $ then the exact spin dynamics of the model is shown to exhibit a periodical short pulses of the polarization of the first spin, the effect being typical of the systems having a large number, $ n $, of spins. if $ n \ gg 1 $, then within the period $ 4 \ pi / g $ ( $ 2 \ pi / g $ ) for odd ( even ) $ n $ - spin clusters, with $ g $ standing for spin coupling, the polarization of spin 1 switches quickly from unity to the time independent value, 1 / 3, over the time interval about $ ( g \ sqrt { n } ) ^ { - 1 } $, thus, almost all the time, the spin 1 spends in the time independent condition $ p _ 1 ( t ) = 1 / 3 $. the period and the width of the pulses determine the volume and the form - factor of the ellipsoidal cavity. the formalism is adopted to the case of time varying nano - fluctuations of the volume of the cavitation nano - bubbles. if the volume $ v ( t ) $ is varied by the gaussian - in - time random noise then the envelope of the polarization peaks goes irreversibly to 1 / 3. the polarization dynamics of the single spin exhibits the gaussian ( or exponential ) time dependence when the correlation time of the fluctuations of the nano - volume is larger ( or smaller ) than the $ < ( \ delta g ) ^ 2 > ^ { - 1 / 2 } $, where the $ < ( \ delta g ) ^ 2 > $ is the variance of the $ g ( v ( t ) ) $ coupling. finally, we report the exact calculations of the nmr line shape for the $ n $ - spin gaseous aggregate.
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arxiv:quant-ph/0306055
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currently, mobile network operators are allocated spectrum bands on an exclusive basis. while this approach facilitates interference control, it may also result in low spectrum utilization efficiency. inter - operator spectrum sharing is a potential method to enhance spectrum utilization. in order to realize it, a protocol to coordinate the actions of operators is needed. we propose a spectrum sharing protocol which is distributed in nature, it does not require operator - specific information exchange and it incurs minimal communication overhead between the operators. operators are still free to decide whether they share spectrum or not as the protocol is based on the book keeping of spectrum usage favors, asked and received by the operators. we show that operators can enhance their qos in comparison with traditional orthogonal spectrum allocation while also maintaining reciprocity i. e. no operator benefits over the other in the long run. we demonstrate the usability of the proposed protocol in an indoor deployment scenario with frequent network load variations as expected to have in small cell deployments.
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arxiv:1505.02898
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we propose simulation strategies for single production of third generation vector - like quarks at the lhc, implementing next - to - leading - order corrections in qcd and studying in detail their effect on cross sections and differential distributions. we also investigate the differences and the relative incertitudes induced by the use of the four - flavour number scheme $ { \ it versus } $ the five - flavour number scheme. as a phenomenological illustration, we concentrate on the production of vector - like quarks coupling to the third generation of the standard model in association with a jet and assuming standard couplings to gauge and higgs bosons.
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arxiv:1811.05055
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high - temperature solid - state reaction between orthorhombic agf2 and monoclinic cuf2 ( y = 0. 15, 0. 3, 0. 4, 0. 5 ) in a fluorine atmosphere resulted in coexisting solid solutions of cu - poor orthorhombic and cu - rich monoclinic phases with stoichiometry ag1 - xcuxf2. based on x - ray powder diffraction analyses, the mutual solubility in the orthorhombic phase ( agf2 doped with cu ) appears to be at an upper limit of cu concentration of 30 mol % ( ag0. 7cu0. 3f2 ), while the monoclinic phase ( cuf2 doped with ag ) can form a nearly stoichiometric cu : ag = 1 : 1 solid solution ( cu0. 56ag0. 44f2 ), preserving the cuf2 crystal structure. experimental data and dft calculations showed that agf2 doped with cu and cuf2 doped with ag solid solutions deviate from the classical vegards law. magnetic measurements of ag1 - xcuxf2 showed that the neel temperature ( tn ) decreases with increasing cu content in both phases. likewise, theoretical dft + u calculations for ag1 - xcuxf2 showed that the progressive substitution of ag by cu decreases the magnetic interaction strength ( j2d ) in both structures. electrical conductivity measurements of ag0. 85cu0. 15f2 showed a ca. 2 - fold increase in specific ionic conductivity ( 3. 71 x 10 - 13 plus / minus 2. 6 x 10 - 15 s / cm ) as compared to pure agf2 ( 1. 85 x 10 - 13 plus / minus 1. 2 x 10 - 15 s / cm ), indicating the formation of a vacancy - or f adatom - free metal difluoride sample.
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arxiv:2304.02257
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abstract data has no natural scale and so interactive data visualizations must provide techniques to allow the user to choose their viewpoint and scale. such techniques are well established in desktop visualization tools. the two most common techniques are zoom + pan and overview + detail. however, how best to enable the analyst to navigate and view abstract data at different levels of scale in immersive environments has not previously been studied. we report the findings of the first systematic study of immersive navigation techniques for 3d scatterplots. we tested four conditions that represent our best attempt to adapt standard 2d navigation techniques to data visualization in an immersive environment while still providing standard immersive navigation techniques through physical movement and teleportation. we compared room - sized visualization versus a zooming interface, each with and without an overview. we find significant differences in participants ' response times and accuracy for a number of standard visual analysis tasks. both zoom and overview provide benefits over standard locomotion support alone ( i. e., physical movement and pointer teleportation ). however, which variation is superior, depends on the task. we obtain a more nuanced understanding of the results by analyzing them in terms of a time - cost model for the different components of navigation : way - finding, travel, number of travel steps, and context switching.
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arxiv:2008.09941
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context : the origin of galactic cosmic rays is still a mystery, in particular the sources and acceleration mechanism for cosmic rays with energies up to or beyond a pev. recently lhaaso has and h. e. s. s have shown that two gamma - ray sources associated with superbubbles created by young massive stellar clusters are likely pevatrons. this has renewed the interest in the cosmic - ray acceleration processes in superbubbles. aims : to study the possibility and conditions under which second - order fermi acceleration can accelerate particles beyond pev energies in superbubbles. methods : an analytical equation is derived for the maximum energy a cosmic - ray particle can obtain as a function of acceleration duration and size. the maximum energy depends critically on the diffusion coefficient d and the alfven velocity, v _ a. the analytical solutions for the acceleration time scale shows that second - order fermi acceleration can be just as efficient as diffusive shock acceleration, when comparable relevant velocities are used - - i. e. the alfven velocity or shock velocity. ultimately, the maximum energy is determined by the diffusive escape of the cosmic rays, which depends on the size and diffusion coefficient. this limits the maximum energy to a few pev for superbubble radii of ~ 50 pc. the probable values for the diffusion coefficient and alven speed are studied for two likely pevatron regions, hess j1646 - 458 associated with westerlund 1, and the cygnus cocoon, associated cyg ob2. results : it is shown that within a typical stellar cluster time scale of 1 - 5 myr cosmic rays can be accelerated to > 10 ^ 15 ev, provided that v _ a > 300 km / s, and the diffusion coefficient is d ~ 10 ^ 26 cm ^ 2s at 100 tev. this suggests that second - order fermi acceleration in superbubbles should be considered as a possible source of galactic cosmic rays up to, or beyond a pev.
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arxiv:2406.03555
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we present the design and implementation of the japanese virtual observatory ( jvo ) system. jvo is a portal site to various kinds of astronomical resources distributed all over the world. we have developed five components for constructing the portal : ( 1 ) registry, ( 2 ) data service, ( 3 ) workflow system, ( 4 ) data analysis service ( 5 ) portal gui. registry services are used for publishing and searching data services in the vo, and they are constructed using an oai - pmh metadata harvesting protocol and a soap web service protocol so that vo standard architecture is applied. data services are developed based on the astronomical data query language ( adql ) which is an international vo standard and an extension of the standard sql. the toolkit for building the adql - based service is released to the public on the jvo web site. the toolkit also provides the protocol translation from a simple image access protocol ( siap ) to adql protocol, so that both the vo standard service can be constructed using our toolkit. in order to federate the distributed databases and analysis services, we have designed a workflow language which is described in xml and developed execution system of the workflow. we have succeeded to connect to a hundred of data resources of the world as of april 2006. we have applied this system to the study of qso environment by federating a qso database, a subaru suprim - cam database, and some analysis services such a sextractor and hyperz web services. these experiences are described is this paper.
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arxiv:astro-ph/0604593
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we formulate the einstein - podolsky - rosen ( epr ) gedankenexperiment within the framework of relativistic quantum theory to analyze a situation in which measurements are performed by moving observers. we point out that under certain conditions the perfect anti - correlation of an epr pair of spins in the same direction is deteriorated in the moving observers ' frame due to the wigner rotation, and show that the degree of the violation of bell ' s inequality prima facie decreases with increasing the velocity of the observers if the directions of the measurement are fixed. however, this does not imply a breakdown of non - local correlation since the perfect anti - correlation is maintained in appropriately chosen different directions. we must take account of this relativistic effect in utilizing in moving frames the epr correlation and the violation of bell ' s inequality for quantum communication.
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arxiv:quant-ph/0211177
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we present the calculations of the complete next - to - leading order ( nlo ) qcd effects on the single top productions induced by model - independent $ tqg $ flavor - changing neutral - current couplings at hadron colliders. our results show that, for the $ tcg $ coupling the nlo qcd corrections can enhance the total cross sections by about 60 % and 30 %, and for the $ tug $ coupling by about 50 % and 20 % at the tevatron and lhc, respectively, which means that the nlo corrections can increase the experimental sensitivity to the fcnc couplings by about 10 % $ - $ 30 %. moreover, the nlo corrections reduce the dependence of the total cross sections on the renormalization or factorization scale significantly, which lead to increased confidence on the theoretical predictions. besides, we also evaluate the nlo corrections to several important kinematic distributions, and find that for most of them the nlo corrections are almost the same and do not change the shape of the distributions.
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arxiv:0910.4349
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we study decentralized protection strategies against susceptible - infected - susceptible ( sis ) epidemics on networks. we consider a population game framework where nodes choose whether or not to vaccinate themselves, and the epidemic risk is defined as the infection probability at the endemic state of the epidemic under a degree - based mean - field approximation. motivated by studies in behavioral economics showing that humans perceive probabilities and risks in a nonlinear fashion, we specifically examine the impacts of such misperceptions on the nash equilibrium protection strategies. we first establish the existence and uniqueness of a threshold equilibrium where nodes with degrees larger than a certain threshold vaccinate. when the vaccination cost is sufficiently high, we show that behavioral biases cause fewer players to vaccinate, and vice versa. we quantify this effect for a class of networks with power - law degree distributions by proving tight bounds on the ratio of equilibrium thresholds under behavioral and true perceptions of probabilities. we further characterize the socially optimal vaccination policy and investigate the inefficiency of nash equilibrium.
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arxiv:1703.08750
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our direct knowledge of solar eruptive events is limited to several decades and does not include extreme events, which can only be studied by the indirect proxy method over millennia, or by a large number of sun - like stars. there is a gap, spanning 1 - - 2 orders of magnitude, in the strength of events between directly observed and reconstructed ones. here, we study the proxy - method sensitivity to identify extreme solar particle events ( spes ). first, the strongest directly observed spe ( 23 - feb - 1956 ), used as a reference for proxy - based reconstructions, was revisited using the newly developed method. next, the sensitivity of the cosmogenic - isotope method to detect a reference spe was assessed against the precision and number of individual isotopic records, showing that it is too weak by a factor $ \ approx $ 30 to be reliably identified in a single record. uncertainties of 10be and 14c data are shown to be dominated by local / regional patterns and measurement errors, respectively. by combining several proxy records, an spe 4 - - 5 times stronger than the reference one can be potentially detected, increasing the present - day sensitivity by an order of magnitude. this will allow filling the observational gap in spe strength distribution, thus enriching statistics of extreme events from 3 - - 4 presently known ones to several tens. this will provide a solid basis for research in the field of extreme events, both for fundamental science, viz. solar and stellar physics, and practical applications, such as the risk assessments of severe space - based hazards for the modern technological society.
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arxiv:2005.10597
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the gravitationally lensed star whl0137 - ls, nicknamed earendel, was identified with a photometric redshift $ z _ { phot } = 6. 2 \ pm 0. 1 $ based on images taken with the hubble space telescope. here we present james webb space telescope ( jwst ) near infrared camera ( nircam ) images of earendel in 8 filters spanning 0. 8 - - 5. 0 $ \ mu $ m. in these higher resolution images, earendel remains a single unresolved point source on the lensing critical curve, increasing the lower limit on the lensing magnification to $ \ mu > 4000 $ and restricting the source plane radius further to $ r < 0. 02 $ pc, or $ \ sim 4000 $ au. these new observations strengthen the conclusion that earendel is best explained by an individual star or multiple star system, and support the previous photometric redshift estimate. fitting grids of stellar spectra to our photometry yields a stellar temperature of $ t _ { \ mathrm { eff } } \ simeq 13000 $ - - 16000 k assuming the light is dominated by a single star. the delensed bolometric luminosity in this case ranges from $ \ log ( l ) = 5. 8 $ - - 6. 6 $ l _ { \ odot } $, which is in the range where one expects luminous blue variable stars. follow - up observations, including jwst nirspec scheduled for late 2022, are needed to further unravel the nature of this object, which presents a unique opportunity to study massive stars in the first billion years of the universe.
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arxiv:2208.09007
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in the standard flat cosmological constant ( $ \ lambda $ ) cold dark matter ( cdm ) cosmology, a model of two populations of lens halos for strong gravitational lensing can reproduce the results of the jodrell - bank vla astrometric survey ( jvas ) and the cosmic lens all - sky survey ( class ) radio survey. in such a model, lensing probabilities are sensitive to three parameters : the concentration parameter $ c _ 1 $, the cooling mass scale $ m _ \ mathrm { c } $ and the value of the cdm power spectrum normalization parameter $ \ sigma _ 8 $. the value ranges of these parameters are constrained by various observations. however, we found that predicted lensing probabilities are also quite sensitive to the flux density ( brightness ) ratio $ q _ { \ mathrm { r } } $ of the multiple lensing images, which has been, in fact, a very important selection criterion of a sample in any lensing survey experiments. we re - examine the above mentioned model by considering the flux ratio and galactic central super massive black holes ( smbhs ), in flat, low - density cosmological models with different cosmic equations of state $ \ omega $, and find that the predicted lensing probabilities without considering $ q _ { \ mathrm { r } } $ are over - estimated. a low value of $ q _ \ mathrm { r } $ can be compensated by raising the cooling mass scale $ m _ \ mathrm { c } $ in fitting the predicted lensing probabilities to jvas / class observations. in order to determine the cosmic equation of state $ \ omega $, the uncertainty in $ m _ \ mathrm { c } $ must be resolved. the effects of smbhs cannot be detected by strong gravitational lensing method when $ q _ { \ mathrm { r } } \ leq 10 $.
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arxiv:astro-ph/0306445
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recurrent neural networks ( rnns ) have achieved state - of - the - art performance on many diverse tasks, from machine translation to surgical activity recognition, yet training rnns to capture long - term dependencies remains difficult. to date, the vast majority of successful rnn architectures alleviate this problem using nearly - additive connections between states, as introduced by long short - term memory ( lstm ). we take an orthogonal approach and introduce mist rnns, a narx rnn architecture that allows direct connections from the very distant past. we show that mist rnns 1 ) exhibit superior vanishing - gradient properties in comparison to lstm and previously - proposed narx rnns ; 2 ) are far more efficient than previously - proposed narx rnn architectures, requiring even fewer computations than lstm ; and 3 ) improve performance substantially over lstm and clockwork rnns on tasks requiring very long - term dependencies.
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arxiv:1702.07805
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smooth solutions of the forced incompressible euler equations satisfy an energy balance, where the rate - of - change in time of the kinetic energy equals the work done by the force per unit time. interesting phenomena such as turbulence are closely linked with rough solutions which may exhibit { \ it inviscid dissipation }, or, in other words, for which energy balance does not hold. this article provides a characterization of energy balance for physically realizable weak solutions of the forced incompressible euler equations, i. e. solutions which are obtained in the limit of vanishing viscosity. more precisely, we show that, in the two - dimensional periodic setting, strong convergence of the zero - viscosity limit is both necessary and sufficient for energy balance of the limiting solution, under suitable conditions on the external force. as a consequence, we prove energy balance for a general class of solutions with initial vorticity belonging to rearrangement - invariant spaces, and going beyond onsager ' s critical regularity.
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arxiv:2404.12572
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a hamiltonian two - field gyrofluid model for kinetic alfv \ ' en waves ( kaws ) in a magnetized electron - proton plasma, retaining ion finite - larmor - radius corrections and parallel magnetic field fluctuations, is used to study the inverse cascades that develop when turbulence is randomly driven at sub - ion scales. in the directions perpendicular to the ambient field, the dynamics of the cascade turns out to be nonlocal and the ratio $ \ chi _ f $ of the wave period to the characteristic nonlinear time at the driving scale affect some of its properties. for example, at small values of $ \ chi _ f $, parametric decay instability of the modes driven by the forcing can develop, enhancing for a while inverse transfers. the balanced state, obtained at early time when the two counter - propagating waves are equally driven, also becomes unstable at small $ \ chi _ f $, leading to an inverse cascade. for $ \ beta _ e $ smaller than a few units, the cascade slows down when reaching the low - dispersion spectral range. for higher $ \ beta _ e $, the ratio of the kaw to the alfv \ ' en frequencies displays a local minimum. at the corresponding transverse wavenumber, a condensate is formed, and the cascade towards larger scales is then inhibited. depending on the parameters, a parallel inverse cascade can develop, enhancing the elongation of the ion - scale magnetic vortices that generically form.
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arxiv:2007.06976
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we use single track laser melting experiments and simulations on inconel 625 to estimate the dimensions and microstructures of the resulting melt pools. our work is based on a design - of - experiments approach which uses multiple laser power and scan speed combinations. single track experiments generate melt pools of certain dimensions. these dimensions reasonably agree with our finite element calculations. phase - field simulations predict the size and segregation of the cellular microstructures that form along the melt pool boundaries for the solidification conditions that change as a function of melt pool dimensions.
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arxiv:1802.05827
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in - depth analyses of existing direct numerical simulations ( dns ) data from various sources supported a logical and important classification of generic turbulent boundary layers ( tbl ), namely type - a, - b and - c tbl, based on distribution patterns of time - averaged wall - shear stress. among these types, type - a tbl and its related law, as represented by the dns data of turbulence on a zero - pressure - gradient semi - infinite flat - plate, was investigated in terms of analytical formulations of velocity independent on reynolds ( ) number. with reference to the analysis from von karman in developing the conventional law - of - the - wall, the current study first physically distinguished the time - averaged local scale used by von karman from the ensemble - averaged scale defined in the paper, and then derived the governing equations with the - independency under the ensemble - averaged scales. based on indicator function ( idf ) and tbl thickness, the sublayer partitions were rigorously defined. the analytical formulations for entire tbl, namely the complete law - of - the - wall, were established, including the formula in inner, buffer, semi - logarithmic ( semi - log ) and wake layer. the researches were featured by introducing the general damping and enhancing functions ( gdf and gef ) and applying these functions to both linear and logarithmic coordinates. these law formulations were proved uniform and consistent in time - averaged local and ensemble - averaged scales, which were validated by the existing dns and experiment data. based on the similarity of relevant properly - scaled governing equations, the law formulations were logically reasoned being applicable to the temperature in type - a thermal tbl. the findings advance the current understandings of the conventional tbl theory and its well - known foundations of law - of - the - wall.
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arxiv:1904.08606
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deep neural networks are incredibly vulnerable to crafted, human - imperceptible adversarial perturbations. although adversarial training ( at ) has proven to be an effective defense approach, we find that the at - trained models heavily rely on the input low - frequency content for judgment, accounting for the low standard accuracy. to close the large gap between the standard and robust accuracies during at, we investigate the frequency difference between clean and adversarial inputs, and propose a frequency regularization ( fr ) to align the output difference in the spectral domain. besides, we find stochastic weight averaging ( swa ), by smoothing the kernels over epochs, further improves the robustness. among various defense schemes, our method achieves the strongest robustness against attacks by pgd - 20, c \ & w and autoattack, on a wideresnet trained on cifar - 10 without any extra data.
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arxiv:2212.12732
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we use extreme value statistics to study the dynamics of coarsening in aggregation - fragmentation models which form condensates in the steady state. the dynamics is dominated by the formation of local condensates on a coarsening length scale which grows in time in both the zero range process and conserved mass aggregation model. the local condensate mass distribution exhibits scaling, which implies anomalously large fluctuations, with mean and standard deviation both proportional to the coarsening length. remarkably, the state of the system during coarsening is governed not by the steady state, but rather a pre - asymptotic state in which the condensate mass fluctuates strongly.
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arxiv:2210.15742
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an expression is obtained on the basis of phase perturbation theory for the contribution to the mean differential reflection coefficient from the in - plane co - polarized component of the light scattered diffusely from a two - dimensional randomly rough dielectric surface when the latter is illuminated by s - polarized light. this result forms the basis for an approach to inverting experimental light scattering data to obtain the normalized surface height autocorrelation function of the surface. several parametrized forms of this correlation function, and the minimization of a cost function with respect to the parameters defining these representations, are used in the inversion scheme. this approach also yields the rms height of the surface roughness, and the dielectric constant of the dielectric substrate if it is not known in advance. the input data used in validating this inversion consists of computer simulation results for surfaces defined by exponential and gaussian surface height correlation functions, without and with the addition of multiplicative noise, for a single or multiple angles of incidence. the reconstructions obtained by this approach are quite accurate for weakly rough surfaces, and the proposed inversion scheme is computationally efficient.
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arxiv:1512.09025
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quantization of constraint systems within the weyl - wigner - groenewold - moyal framework is discussed. constraint dynamics of classical and quantum systems is reformulated using the skew - gradient projection formalism. the quantum deformation of the dirac bracket is generalized to match smoothly the classical dirac bracket in and outside of the constraint submanifold in the limit $ \ hbar \ to 0 $.
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arxiv:hep-th/0610074
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