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a search for rare $ b \ rightarrow d \ mu ^ + \ mu ^ - $ decays is performed using proton - proton collision data collected by the lhcb experiment, corresponding to an integrated luminosity of 9 fb $ ^ { - 1 } $. no significant signals are observed in the non - resonant $ \ mu ^ + \ mu ^ - $ modes, and upper limits of $ \ mathcal { b } ( b ^ 0 \ rightarrow \ overline { d } ^ 0 \ mu ^ + \ mu ^ - ) < 5. 1 \ times 10 ^ { - 8 } $, $ \ mathcal { b } ( b ^ + \ rightarrow d _ s ^ + \ mu ^ + \ mu ^ - ) < 3. 2 \ times 10 ^ { - 8 } $, $ \ mathcal { b } ( b _ s ^ 0 \ rightarrow \ overline { d } ^ 0 \ mu ^ + \ mu ^ - ) < 1. 6 \ times 10 ^ { - 7 } $ and $ f _ c / f _ u \ cdot \ mathcal { b } ( b _ c ^ + \ rightarrow d _ s ^ + \ mu ^ + \ mu ^ - ) < 9. 6 \ times 10 ^ { - 8 } $ are set at the 95 \ % confidence level, where $ f _ c $ and $ f _ u $ are the fragmentation fractions of a $ b $ meson with a $ c $ and $ u $ quark respectively in proton - proton collisions. each result is either the first such measurement or an improvement by three orders of magnitude on an existing limit. separate upper limits are calculated when the muon pair originates from a $ j / \ psi \ rightarrow \ mu ^ + \ mu ^ - $ decay. the branching fraction of $ b _ c ^ + \ rightarrow d _ s ^ + j / \ psi $ multiplied by the fragmentation - fraction ratio is measured to be $ f _ c / f _ u \ cdot \ mathcal { b } ( b _ c ^ + \ rightarrow d _ s ^ + j / \ psi ) = ( 1. 63 \ pm 0. 15 \ pm 0. 13 ) \ times 10 ^ { - 5 } $, where the first uncertainty is statistical and the second systematic. | arxiv:2308.06162 |
this article is devoted to introduce a new notion of periodicity shadow, which appeared naturally in the study of combinatorics of tame symmetric algebras of period four, or more generally, algebras of generalized quaternion type. for any such an algebra $ \ la $, we consider its shadow $ \ bs _ \ la $, which is the ( signed ) adjacency matrix of the gabriel quiver of $ \ la $. studying properties of shadows $ \ bs _ \ la $ leads us to the definition of the periodicity shadow, which is basically, a skew - symmetric integer matrix satisfying certain set of conditions motivated by the properties of shadows $ \ bs _ \ la $. this turned out to be a very useful tool in describing the combinatorics of gabriel quivers of algebras of generalized quaternion type, not only for algebras with small gabriel quivers ( i. e. up to $ 6 $ vertices ), which it was originally desined for. in this paper, we introduce and briefly discuss this notion and present one of its theoretical applications, which shows how significant it is. namely, the main result of this paper describes the global shape of the gabriel quivers of algebras of generalized quaternion type, as quivers obtained from some basic shadows by attaching $ 2 $ - cycles, and moreover, postion of the $ 2 $ - cycles is restricted by precise rules ( see the main theorem ). computational aspects are reported in the second part. | arxiv:2411.17381 |
in this proposal paper we highlight the need for privacy preserving energy demand forecasting to allay a major concern consumers have about smart meter installations. high resolution smart meter data can expose many private aspects of a consumer ' s household such as occupancy, habits and individual appliance usage. yet smart metering infrastructure has the potential to vastly reduce carbon emissions from the energy sector through improved operating efficiencies. we propose the application of a distributed machine learning setting known as federated learning for energy demand forecasting at various scales to make load prediction possible whilst retaining the privacy of consumers ' raw energy consumption data. | arxiv:2012.07449 |
in this paper, the photocatalytic activity of multiferroics bifeo3 ( bfo ) and bi0. 8la0. 2feo3 ( blfo ) nanocrystals with two different morphologies which were synthesized by two different sol - gel ( sg ) and hydrothermal ( ht ) methods have been studied. all the obtained samples were characterized using x - ray diffractometer, fourier transform infrared spectroscopy, transmission electron microscopy, uv - vis spectroscopy and vibrating sample magnetometer. differential thermal analysis ( dta ) measurements were probed ferroelectric - paraelectric first - order phase transition ( tc ) for all samples. addition of lanthanum decreases the electric phase transition. for photocatalyst application of bismuth ferrite, adsorption potential of nanoparticles for methylene blue ( mb ) organic dye was evaluated. the doping of la in the bfo structure enhanced the photocatalytic activity and about 71 % degradation of mb dye was obtained under visible irradiation. the magnetic and ferroelectric properties of blfo nanoparticles improve compared to the undoped bifeo3 nanoparticles. the non - saturation at high applied magnetic field for as - prepared samples by ht is related to the size and shape of products. this work not only presents an effect of lanthanum substitution into the bismuth ferrite structure on the physical properties of bfo, but also compares the synthesis method and its influence on the photocatalytic activity and multiferroics properties of all nanopowders. | arxiv:1807.03127 |
( abridged ) we present a comprehensive comparison of the x - ray properties of a sample of eight dwarf starburst galaxies observed with chandra ( i zw 18, vii zw 403, ngc 1569, ngc 3077, ngc 4214, ngc 4449, ngc 5253, he 2 - 10 ). in paper i we presented in detail the data reduction and analysis of the individual galaxies. for the unresolved x - ray sources we find the following : point sources are in general located close to bright hii regions, rims of superbubbles, or young stellar clusters. the number of x - ray point sources appears to be a function of the current star formation rate and the blue luminosity of the hosts. ultraluminous x - ray sources are only found in those dwarf galaxies which are currently interacting. the power law index of the combined cumulative x - ray point source luminosity function is alpha = 0. 24 + / - 0. 06, shallower than that of more massive starburst galaxies ( alpha = 0. 4 - 0. 8 ) and of non - starburst galaxies ( alpha ~ 1. 2 ). for those galaxies showing extended x - ray emission ( 6 out of the 8 galaxies ), we derive the following : superwinds develop along the steepest gradient of the hi distribution with volume densities of 0. 02 - 0. 06 cm ^ - 3, pressures of 1 - 3x10 ^ 5 k cm ^ - 3, thermal energies of 2 - 30x10 ^ 54 erg, and hot gas masses of 2 - 20x10 ^ 6 mo ( ~ 1 per cent of the hi masses ). the mechanical luminosities of the developing superwinds are energetic enough to overcome the gravitational potentials of their host galaxies. this scenario is supported by the overpressures of the hot gas compared to the ambient ism. extended hi envelopes such as tidal tails, however, may delay outflows on timescales exceeding those of the cooling time of the hot gas. | arxiv:astro-ph/0501528 |
we show that an embedding of a fixed 0 - dimensional compact space $ k $ into the \ v { c } ech - - stone remainder $ \ omega ^ * $ as a nowhere dense p - set is the unique generic limit, a special object in the category consisting of all continuous maps from $ k $ to compact metric spaces. using fra \ " iss \ ' e theory we get a few well know theorems about \ v { c } ech - - stone remainder. we establish the following : - - an ultrametric space $ k $ of weight $ \ kappa $ can be uniformly embedded into $ \ kappa ^ \ kappa $ as a uniformly nowhere dense subset, - - every uniform homeomorphism of uniformly nowhere dense sets in $ \ kappa ^ \ kappa $ can be extended to a uniform auto - homeomorphism of $ \ kappa ^ \ kappa $, - - every uniformly nowhere dense set in $ \ kappa ^ \ kappa $ is a uniform retract of $ \ kappa ^ \ kappa $. if we assume that $ \ kappa $ is a weakly compact cardinal we get the counterpart of the above result without the uniformity assumption. | arxiv:2310.05043 |
some statistical models are specified via a data generating process for which the likelihood function cannot be computed in closed form. standard likelihood - based inference is then not feasible but the model parameters can be inferred by finding the values which yield simulated data that resemble the observed data. this approach faces at least two major difficulties : the first difficulty is the choice of the discrepancy measure which is used to judge whether the simulated data resemble the observed data. the second difficulty is the computationally efficient identification of regions in the parameter space where the discrepancy is low. we give here an introduction to our recent work where we tackle the two difficulties through classification and bayesian optimization. | arxiv:1502.05503 |
a two - parametric non - standard ( jordanian ) deformation of the lie algebra $ gl ( 2 ) $ is constructed, and then, exploited to obtain a new, triangular r - matrix solution of the coloured yang - baxter equation. the corresponding coloured quantum group is presented explicitly. | arxiv:q-alg/9705027 |
the picture - word interference paradigm ( participants name target pictures while ignoring distractor words ) is often used to model the planning processes involved in word production. the participants ' naming times are delayed in the presence of a distractor ( general interference ). the size of this effect depends on the relationship between the target and distractor words. distractors of the same semantic category create more interference ( semantic interference ), distractors overlapping in phonology create less interference ( phonological facilitation ). the present study examines the relationships between these experimental effects, processing times, and attention in order to better understand the cognitive processes underlying participants ' behavior in this paradigm. participants named pictures with a superimposed line of xs, semantically related distractors, phonologically related distractors, or unrelated distractors. general interference, semantic interference, and phonological facilitation effects are replicated. distributional analyses reveal that general and semantic interference effects increase with naming times, while phonological facilitation decreases. the phonological facilitation and semantic interference effects are found to depend on the synchronicity in processing times between the planning of the picture ' s name and the processing of the distractor word. finally, eeg power in the alpha band before stimulus onset varied with the position of the trial in the experiment and with repetition but did not predict the size of interference or facilitation effects. taken together, these results suggest that experimental effects in the picture - word interference paradigm depend on processing times to both the target word and distractor word and that distributional patterns could party reflect this dependency. | arxiv:2303.09201 |
the km3net research infrastructure being built at the bottom of the mediterranean sea will host water - cherenkov telescopes for the detection of cosmic neutrinos. the neutrino telescopes will consist of large volume three - dimensional grids of optical modules to detect the cherenkov light from charged particles produced by neutrino - induced interactions. each optical module houses 31 3 - inch photomultiplier tubes, instrumentation for calibration of the photomultiplier signal and positioning of the optical module and all associated electronics boards. by design, the total electrical power consumption of an optical module has been capped at seven watts. this paper presents an overview of the front - end and readout electronics system inside the optical module, which has been designed for a 1 ~ ns synchronization between the clocks of all optical modules in the grid during a life time of at least 20 years. | arxiv:1907.06453 |
distributed consensus computation over random graph processes is considered. the random graph process is defined as a sequence of random variables which take values from the set of all possible digraphs over the node set. at each time step, every node updates its state based on a bernoulli trial, independent in time and among different nodes : either averaging among the neighbor set generated by the random graph, or sticking with its current state. connectivity - independence and arc - independence are introduced to capture the fundamental influence of the random graphs on the consensus convergence. necessary and / or sufficient conditions are presented on the success probabilities of the bernoulli trials for the network to reach a global almost sure consensus, with some sharp threshold established revealing a consensus zero - one law. convergence rates are established by lower and upper bounds of the $ \ epsilon $ - computation time. we also generalize the concepts of connectivity / arc independence to their analogues from the $ * $ - mixing point of view, so that our results apply to a very wide class of graphical models, including the majority of random graph models in the literature, e. g., erd \ h { o } s - r \ ' { e } nyi, gossiping, and markovian random graphs. we show that under $ * $ - mixing, our convergence analysis continues to hold and the corresponding almost sure consensus conditions are established. finally, we further investigate almost sure finite - time convergence of random gossiping algorithms, and prove that the bernoulli trials play a key role in ensuring finite - time convergence. these results add to the understanding of the interplay between random graphs, random computations, and convergence probability for distributed information processing. | arxiv:1112.1336 |
the advent of high - angular resolution ir and sub - mm interferometry allows for spatially - resolved observations of the parsec - scale environment of active galactic nuclei ( agn ), commonly referred to as the " torus. " while molecular lines show the presence of large, massive disks, the ir observations appear to be dominated by a strong polar component that has been interpreted as a dusty wind. this paper aims at using characteristics shared by agn in each of the wavebands and a set of simple physical principles to form a unifying view of these seemingly contradictory observations : dusty molecular gas flows in from galactic scales of ~ 100 pc to the sub - parsec environment via a disk with small to moderate scale height. the hot, inner part of the disk puffs up due to ir radiation pressure and unbinds a large amount of the inflowing gas from the black hole ' s gravitational potential, providing the conditions to launch a wind driven by the radiation pressure from the agn. the dusty wind feeds back mass into the galaxy at a rate of the order of ~ 0. 1 - 100 $ m _ \ odot $ / yr, depending on agn luminosity and eddington ratio. angle - dependent obscuration as required by agn unification is provided by a combination of disk, wind, and wind launching region. | arxiv:1909.08639 |
hiding an object in a chemical gradient requires to suppress the distortions it would naturally cause on it. to do so, we propose a strategy based on coating the object with a chemical reaction - diffusion network which can act as an active cloaking device. by controlling the concentration of some species in its immediate surrounding, the chemical reactions redirect the gradient as if the object was not there. we also show that a substantial fraction of the energy required to cloak can be extracted from the chemical gradient itself. | arxiv:1911.06227 |
we consider two ansatze for the neutrino masses and mixings in which the permutation symmetry is implemented in various orders. we discuss the possible see - saw mechanisms and the charged lepton masses for the two cases in the presence of a higgs triplet and three higgs doublets. | arxiv:1312.2308 |
a long continuous integration ( ci ) build forces developers to wait for ci feedback before starting subsequent development activities, leading to time wasted. in addition to a variety of build scheduling and test selection heuristics studied in the past, new artifact - based build technologies like bazel have built - in support for advanced performance optimizations such as parallel build and incremental build ( caching of build results ). however, little is known about the extent to which new build technologies like bazel deliver on their promised benefits, especially for long - build duration projects. in this study, we collected 383 bazel projects from github, then studied their parallel and incremental build usage of bazel in 4 popular ci services, and compared the results with maven projects. we conducted 3, 500 experiments on 383 bazel projects and analyzed the build logs of a subset of 70 buildable projects to evaluate the performance impact of bazel ' s parallel builds. additionally, we performed 102, 232 experiments on the 70 buildable projects ' last 100 commits to evaluate bazel ' s incremental build performance. our results show that 31. 23 % of bazel projects adopt a ci service but do not use bazel in the ci service, while for those who do use bazel in ci, 27. 76 % of them use other tools to facilitate bazel ' s execution. compared to sequential builds, the median speedups for long - build duration projects are 2. 00x, 3. 84x, 7. 36x, and 12. 80x, at parallelism degrees 2, 4, 8, and 16, respectively, even though, compared to a clean build, applying incremental build achieves a median speedup of 4. 22x ( with a build system tool - independent ci cache ) and 4. 71x ( with a build system tool - specific cache ) for long - build duration projects. our results provide guidance for developers to improve the usage of bazel in their projects. | arxiv:2405.00796 |
we discuss recent progress in describing a certain non - abelian vortex string as a critical superstring on a conifold and clarify some subtle points. this particular solitonic vortex is supported in four - dimensional n = 2 supersymmetric qcd with the u ( 2 ) gauge group, n _ f = 4 quark flavors and the fayet - iliopoulos term. under certain conditions the non - abelian vortex can become infinitely thin and can be interpreted as a critical ten - dimensional superstring. in addition to four translational moduli the non - abelian vortex under consideration carries six orientational and size moduli. the vortex moduli dynamics are described by a two - dimensional sigma model with the target space { r } ^ 4 \ times y _ 6 where y _ 6 is a non - compact calabi - yau conifold. the closed string states which emerge in four dimensions ( 4d ) are identified with hadrons of 4d bulk n = 2 qcd. it turns out that most of the states arising from the ten - dimensional graviton spectrum are non - dynamical in 4d. a single dynamical massless hypermultiplet associated with the deformation of the complex structure of the conifold is found. it is interpreted as a monopole - monopole baryon of the 4d theory ( at strong coupling ). | arxiv:1611.03111 |
extragalactic globular clusters ( egcs ) are an abundant and powerful tracer of galaxy dynamics and formation, and their own formation and evolution is also a matter of extensive debate. the compact nature of globular clusters means that they are hard to spatially resolve and thus study outside the local group. in this work we have examined how well egcs will be detectable in images from the euclid telescope, using both simulated pre - launch images and the first early - release observations of the fornax galaxy cluster. the euclid wide survey will provide high - spatial resolution vis imaging in the broad ie band as well as near - infrared photometry ( ye, je, and he ). we estimate that the galaxies within 100 mpc in the footprint of the euclid survey host around 830 000 egcs of which about 350 000 are within the survey ' s detection limits. for about half of these egcs, three infrared colours will be available as well. for any galaxy within 50mpc the brighter half of its gc luminosity function will be detectable by the euclid wide survey. the detectability of egcs is mainly driven by the residual surface brightness of their host galaxy. we find that an automated machine - learning egc - classification method based on real euclid data of the fornax galaxy cluster provides an efficient method to generate high purity and high completeness gc candidate catalogues. we confirm that egcs are spatially resolved compared to pure point sources in vis images of fornax. our analysis of both simulated and first on - sky data show that euclid will increase the number of gcs accessible with high - resolution imaging substantially compared to previous surveys, and will permit the study of gcs in the outskirts of their hosts. euclid is unique in enabling systematic studies of egcs in a spatially unbiased and homogeneous manner and is primed to improve our understanding of many understudied aspects of gc astrophysics. | arxiv:2405.14015 |
we discuss the glueball contribution to the equation of state ( eos ) of hot gluon matter below and above $ t _ c $. it is shown that the strong changing of masses of scalar and pseudoscalar glueballs near $ t _ c $ plays very important role in the thermodynamics of $ su ( 3 ) $ gauge theory. in particular, we give the arguments that these glueballs become massless at $ t _ g \ approx 1. 1t _ c $ and this phenomenon is crucial in understanding of the mystery in the behavior of trace anomaly founded in the lattice calculation. | arxiv:1601.05145 |
the bethe - salpeter equation ( bse ) based on gw quasiparticle levels is a successful approach for calculating the optical gaps and spectra of solids and also for predicting the neutral excitations of small molecules. we here present an all - electron implementation of the gw + bse formalism for molecules, using numeric atom - centered orbital ( nao ) basis sets. we present benchmarks for low - lying excitation energies for a set of small organic molecules, denoted in the literature as " thiel ' s set ". literature reference data based on gaussian - type orbitals are reproduced to about one mev precision for the molecular benchmark set, when using the same gw quasiparticle energies and basis sets as the input to the bse calculations. for valence correlation consistent nao basis sets, as well as for standard nao basis sets for ground state density - functional theory with extended augmentation functions, we demonstrate excellent convergence of the predicted low - lying excitations to the complete basis set limit. a simple and affordable augmented nao basis set denoted " tier2 + aug2 " is recommended as a particularly efficient formulation for production calculations. we finally demonstrate that the same convergence properties also apply to linear - response time - dependent density functional theory within the nao formalism. | arxiv:1908.01431 |
a schwarzschild black hole ( bh ) is the gravitational field due to a neutral point mass, and it turns out that the gravitational mass of a neutral point mass : $ m = 0 $ ( arnowitt, deser, misner, prl 4, 375, 1960 ). the same result is also suggested by janis, newman, and winicour ( prl 20, 878, 1968 ). in 1969, bel gave an explicit proof that for a schwarzschild bh, $ m = 0 $ ( bel, jmp 10, 1051, 1969 ). the same result follows from the fact the timelike geodesic of a test particle would turn null if it would ever arrive at an event horizon ( mitra, fpl, 2000, 2002 ). non - occurrrence of trapped surfaces in continued gravitational collapse too demands $ m = 0 $ for black hole ( mitra, pramana, 73, 615, 2009 ). physically, for a point mass at $ r = 0 $, one expects $ { \ it ric } \ sim m \ delta ( r = 0 ) $ ( narlikar \ & padmanabhan, found. phys., 18, 659, 1988 ). but the black hole solution is obtained from $ { \ it ric } = 0 $. again this is the most direct proof that $ m = 0 $ for a schwarzschild black hole. implication of this result is that the observed massive black hole candidates are non - singular quasi black holes or black hole mimickers which can possess strong magnetic fields as has been observed. the echoes from ligo signals, if true, may be the direct evidence that the pertinent compact objects are bh mimickers and not true vacuum bhs. | arxiv:1708.07404 |
we present a measurement of the decay b - - > tau - nu _ bar using a data sample containing 657 million bb _ bar pairs collected at the upsilon ( 4s ) resonance with the belle detector at the kekb asymmetric - energy e + e - collider. a sample of bb _ bar pairs are tagged by reconstructing one b meson decaying semileptonically. we detect the b - - > tau - nu _ bar candidate in the recoil. we obtain a signal with a significance of 3. 6 standard deviations including systematic uncertainties, and measure the branching fraction to be br ( b - - > tau - nu _ bar ) = [ 1. 54 + 0. 38 - 0. 37 ( stat ) + 0. 29 - 0. 31 ( syst ) ] * 10 ^ - 4. this result confirms the evidence for b - - > tau - nu _ bar obtained in a previous belle measurement that used a hadronic b tagging method. | arxiv:1006.4201 |
we describe a physics simulation software framework, mage, that is based on the geant4 simulation toolkit. mage is used to simulate the response of ultra - low radioactive background radiation detectors to ionizing radiation, specifically the majorana and gerda neutrinoless double - beta decay experiments. majorana and gerda use high - purity germanium detectors to search for the neutrinoless double - beta decay of 76ge, and mage is jointly developed between these two collaborations. the mage framework contains the geometry models of common objects, prototypes, test stands, and the actual experiments. it also implements customized event generators, geant4 physics lists, and output formats. all of these features are available as class libraries that are typically compiled into a single executable. the user selects the particular experimental setup implementation at run - time via macros. the combination of all these common classes into one framework reduces duplication of efforts, eases comparison between simulated data and experiment, and simplifies the addition of new detectors to be simulated. this paper focuses on the software framework, custom event generators, and physics lists. | arxiv:1011.3827 |
several key problems of qcd sum rules in the spin - 0 glueball channels are resolved by implementing nonperturbative short - distance physics from direct instantons and topological charge screening. a lattice - based instanton size distribution and the ir renormalization of the nonperturbative wilson coefficients are also introduced. results of a comprehensive quantitative sum rule analysis are reviewed and their implications discussed. | arxiv:hep-ph/0608071 |
the nuclear matter, deconfined quark matter, and quarkyonic matter in low temperature region are classified based on the 1 / nc expansion. the chiral symmetry in the quarkyonic matter is investigated by taking into account condensations of chiral particle - hole pairs. it is argued that the chiral symmetry and parity are locally violated by the formation of chiral spirals, < psibar exp ( 2 i mu z gamma ^ 0 gamma ^ z ) psi >. an extension to multiple chiral spirals is also briefly discussed. | arxiv:1009.5130 |
polyelectrolytes in poor solvents show a necklace structure where collapsed polymer pearls are linked to stretched strings. in the present paper the elasticity of such chains is studied in detail. different deformation regimes are addressed. the first is the continuous regime, where many pearls are present. a continuous force extension relation ship is calculated. the main contribution comes from the tension balance and the electrostatic repulsion of consecutive pearls. the main correction term stems from the finite size of the pearls, which monitors their surface energy. for a finite amount of pearls discontinuous stretching is predicted. finally counterion effects are discussed qualitatively. | arxiv:cond-mat/0001140 |
this paper reports a measurement of the w + b - jets production cross - section in proton - proton collisions at a centre - of - mass energy of 7 tev at the lhc. these results are based on data corresponding to an integrated luminosity of 4. 6 fb - 1, collected with the atlas detector. cross - sections are presented as a function of jet multiplicity and of the transverse momentum of the leading b - jet for both the muon and electron decay modes of the w boson. the w + b - jets cross - section, corrected for all known detector effects, is quoted in a limited kinematic range, using jets reconstructed with the anti - k _ t clustering algorithm with transverse momentum above 25 gev and rapidity within + / - 2. 1. combining the muon and electron channels, the fiducial cross - section for w + b - jets is measured to be 7. 1 + / - 0. 5 ( stat ) + / - 1. 4 ( syst ) pb, consistent with next - to - leading order qcd calculations within 1. 5 standard deviations. | arxiv:1302.2929 |
the paper explores a theoretical possibility of resonant amplification of electromagnetic modes generated by a nonlinear effect in euler - heisenberg electrodynamics. precisely, we examine the possibility of the amplification for the third harmonics induced by a single electromagnetic mode in radiofrequency cavity, as well as the generation of signal mode of combined frequencies induced by two pump modes ( $ \ omega _ 1 $ and $ \ omega _ 2 $ ) in the cavity. solving inhomogeneous wave equations for the signal mode, we formulate two resonant conditions for a cavity of arbitrary shape, and apply the obtained formalism to linear and rectangular cavities. we explicitly show that the third harmonics as well as the mode of combined frequency $ 2 \ omega _ 1 + \ omega _ 2 $ are not resonantly amplified while the signal mode with frequency $ 2 \ omega _ 1 - \ omega _ 2 $ is amplified for a certain cavity geometry. | arxiv:2110.04490 |
we begin the systematic model theoretic study of $ \ mathrm { c } ^ * $ - algebras using the tools of continuous logic. | arxiv:1602.08072 |
author name disambiguation ( and ) is a critical task for digital libraries aiming to link existing authors with their respective publications. due to the lack of persistent identifiers used by researchers and the presence of intrinsic linguistic challenges, such as homonymy, the development of deep learning algorithms to address this issue has become widespread. many and deep learning methods have been developed, and surveys exist comparing the approaches in terms of techniques, complexity, performance. however, none explicitly addresses and methods in the context of deep learning in the latest years ( i. e. timeframe 2016 - 2024 ). in this paper, we provide a systematic review of state - of - the - art and techniques based on deep learning, highlighting recent improvements, challenges, and open issues in the field. we find that dl methods have significantly impacted and by enabling the integration of structured and unstructured data, and hybrid approaches effectively balance supervised and unsupervised learning. | arxiv:2503.13448 |
the growing demand for electric vehicles requires the development of automated car charging methods. at the moment, the process of charging an electric car is completely manual, and that requires physical effort to accomplish the task, which is not suitable for people with disabilities. typically, the effort in the research is focused on detecting the position and orientation of the socket, which resulted in a relatively high accuracy, $ \ pm 5 \ : mm $ and $ \ pm 10 ^ o $. however, this accuracy is not enough to complete the charging process. in this work, we focus on designing a novel methodology for robust robotic plug - in and plug - out based on human haptics, to overcome the error in the position and orientation of the socket. participants were invited to perform the charging task, and their cognitive capabilities were recognized by measuring the applied forces along with the movement of the charger. three controllers were designed based on impedance control to mimic the human patterns of charging an electric car. the recorded data from humans were used to calibrate the parameters of the impedance controllers : inertia $ m _ d $, damping $ d _ d $, and stiffness $ k _ d $. a robotic validation was performed, where the designed controllers were applied to the robot ur10. using the proposed controllers and the human kinesthetic data, it was possible to successfully automate the operation of charging an electric car. | arxiv:2310.12044 |
protein - stabilised emulsions can be seen as mixtures of unadsorbed proteins and of protein - stabilised droplets. to identify the contributions of these two components to the overall viscosity of sodium caseinate o / w emulsions, the rheological behaviour of pure suspensions of proteins and droplets were characterised, and their properties used to model the behaviour of their mixtures. these materials are conveniently studied in the framework developed for soft colloids. here, the use of viscosity models for the two types of pure suspensions facilitates the development of a semi - empirical model that relates the viscosity of protein - stabilised emulsions to their composition. | arxiv:1810.03905 |
we use the pieri and giambelli formulas of arxiv : 0809. 4966 and arxiv : 1109. 6669 and the calculus of raising operators developed in arxiv : 0811. 2781 and arxiv : 0812. 0639 to prove a tableau formula for eta polynomials of arxiv : 1109. 6669 and the stanley symmetric functions which correspond to grassmannian elements of the weyl group $ w _ n $ of type $ d _ n $. we define the skew elements of $ w _ n $ and exhibit a bijection between the set of reduced words for any skew element $ w $ in $ w _ n $ and a set of certain standard typed tableaux on a skew shape $ \ lambda / \ mu $ associated to $ w $. | arxiv:1109.6702 |
in this paper, we give a generate function for the $ \ sigma _ 1 $ function. then we find some connections between the $ \ sigma _ 1 $ function and the ramanujan ' s tau function. we hope this connection will give some insights into the unsolved problems in classical number theory. | arxiv:1102.1155 |
the results, different aspects and applications of our method of quantisation on configuration manifolds - called borel quantisation - were presented at meetings of the series ` symmetries in science ' and can be found in the published proceedings. the developments with numerous coauthors, on borel quantisation and the related family of nonlinear schr \ " odinger equations called doebner - goldin equations, are reviewed and commented here. | arxiv:quant-ph/0601176 |
we address the problem of tracking and detecting interactions between the different groups of runners that form during a race. in athletic races control points are set to monitor the progress of athletes over the course. intuitively, a { \ it group } is a sufficiently large set of athletes that cross a control point together. after adapting an existing definition of group to our setting we go on to study two types of group evolution patterns. the primary focus of this work are { \ it evolution patterns }, i. e. the transformation and interaction of groups of athletes between two consecutive control points. we provide an accurate geometric model of the following evolution patterns : survives, appears, disappears, expands, shrinks, merges, splits, coheres and disbands, and present algorithms to efficiently compute these patterns. next, based on the algorithms introduced for identifying evolution patterns, algorithms to detect { \ it long - term patterns } are introduced. these patterns track global properties over several control points : surviving, traceable forward, traceable backward and related forward and backward. experimental evaluation of the algorithms provided is presented using real and synthetic data. using the data currently available, our experiments show how our algorithms can provide valuable insight into how running races develop. moreover, we also show how, even if dense ( synthetic ) data is considered, our algorithms are also able to process it in real time. | arxiv:1812.10530 |
in this paper we study concentrated solutions of the three - dimensional euler equations in helical symmetry without swirl. we prove that any helical vorticity solution initially concentrated around helices of pairwise distinct radii remains concentrated close to filaments. as suggested by the vortex filament conjecture, we prove that those filaments are translating and rotating helices. similarly to what is obtained in other frameworks, the localization is weak in the direction of the movement but strong in its normal direction, and holds on an arbitrary long time interval in the naturally rescaled time scale. in order to prove this result, we derive a new explicit formula for the singular part of the biot - savart kernel in a two - dimensional reformulation of the problem. this allows us to obtain an appropriate decomposition of the velocity field to reproduce recent methods used to describe the dynamics of vortex rings or point - vortices for the lake equation. | arxiv:2403.00389 |
we expand on prior results on noise supported signal propagation in arrays of coupled bistable elements. we present and compare experimental and numerical results for kink propagation under the influence of local and global fluctuations. as demonstrated previously for local noise, an optimum range of global noise power exists for which the medium acts as a reliable transmission ` ` channel ' '. we discuss implications for propagation failure in a model of cardiac tissue and present a general theoretical framework based on discrete kink statistics. valid for generic bistable chains, the theory captures the essential features ob served in our experiments and numerical simulations. | arxiv:nlin/0003048 |
some form factors of ground - state hadrons with spin might show a zero crossing at spacelike momenta of electron - hadron scattering. in the timelike region of hadron - antihadron production by electron - positron collisions the form factors become complex. when the hadrons decay, the relative phases between form factors can be measured by the angular distributions of their decay products. using analyticity and the qcd high - energy limits for constraint - free form factors and for helicity amplitudes, we show how a single zero crossing in the spacelike region is related to the high - energy limit of the phase in the timelike region. theoretical predictions for such zero crossings can therefore be tested by experimental measurements, e. g. by belle ii, in the high - energy timelike region. in the present work, this line of reasoning is applied to vector mesons. | arxiv:2112.12781 |
we investigate to what extent the oscillation or conversion of neutrinos enhances the expected event rate of the supernova relic neutrino background ( srn ) at the super - kamiokande detector ( sk ). the srn \ bar \ nu _ e ' s can be almost completely exchanged with \ nu _ \ mu - like neutrinos by the msw oscillation under the inverse mass hierarchy with \ delta m ^ 2 ~ 10 ^ { - 8 } - - 10 ^ 5 [ ev ^ 2 ], or by the magnetic moment of majorana neutrinos with \ mu _ \ nu > ~ 10 ^ { - 12 } \ mu _ b and \ delta m ^ 2 ~ 10 ^ { - 4 } - - 10 ^ 0 [ ev ^ 2 ]. in the standard calculation of the srn flux, the event rate of the srn \ bar \ nu _ e ' s at the sk in the observable energy range of 15 - - 40 mev can be enhanced from 1. 2 yr ^ { - 1 } to 2. 4 yr ^ { - 1 } if all \ bar \ nu _ e ' s are exchanged with \ nu _ \ mu - like neutrinos. the enhancement is prominent especially in the high energy range ( \ gtilde 25 mev ). in the astrophysically optimistic calculation, the event rate becomes as high as 9. 4 yr ^ { - 1 }. because the theoretical upper bound of the srn events without oscillation is about 5 yr ^ { - 1 } taking account of the various astrophysical uncertainties, we might have to resort to the neutrino oscillation if more than 5 events in a year, as well as a significantly harder spectrum, were observed in the sk. | arxiv:hep-ph/9609241 |
we continue the coxeter spectral analysis of finite connected posets $ i $ that are non - negative in the sense that their symmetric gram matrix $ g _ i : = \ frac { 1 } { 2 } ( c _ i + c _ i ^ { tr } ) \ in \ mathbb { m } _ { m } ( \ mathbb { q } ) $ is positive semi - definite of rank $ n \ geq 0 $, where $ c _ i \ in \ mathbb { m } _ m ( \ mathbb { z } ) $ is the incidence matrix of $ i $ encoding the relation $ \ preceq _ i $. we extend the results of [ fundam. inform., 139. 4 ( 2015 ), 347 - - 367 ] and give a complete coxeter spectral classification of finite connected posets $ i $ of dynkin type $ \ mathbb { a } _ n $. we show that such posets $ i $, with $ | i | > 1 $, yield exactly $ \ lfloor \ frac { m } { 2 } \ rfloor $ coxeter types, one of which describes the positive ( i. e., with $ n = m $ ) ones. we give an exact description and calculate the number of posets of every type. moreover, we prove that, given a pair of such posets $ i $ and $ j $, the incidence matrices $ c _ i $ and $ c _ j $ are $ \ mathbb { z } $ - congruent if and only if $ \ mathbf { specc } _ i = \ mathbf { specc } _ j $, and present deterministic algorithms that calculate a $ \ mathbb { z } $ - invertible matrix defining such a $ \ mathbb { z } $ - congruence in a polynomial time. | arxiv:2205.15813 |
metal - organic frameworks comprehend a wide class of hybrid organic - inorganic materials with general structure a $ _ m $ bx $ _ n $, with $ a $ and $ x $ being organic molecules and b a metal cation. this often results in enhanced structural flexibility and new functionalities. hybrid perovskites abx $ _ 3 $ are a well - known example. } in an iron - based perovskites, ( dma ) fe ^ { ii - iii } ( cooh ) _ 3, dimethylammonium ( dma ) molecules are organized in a hexagonal structure. they are orientationally disordered at high temperatures, but order at around $ t = 100 $ ~ k in a peculiar toroidal pattern. recent experimental and theoretical study suggest the appearance of ferroelectric polarization in this phase, although the measured polarization is small, and the mechanism of ferroelectricity is still debated. we formulate a landau - type theory that clarifies the connection between the electric polarization, molecular pattern, and distortive modes of the inorganic lattice. we find a remarkable mechanism of improper ferroelectricity, analogue to the trimerization process in inorganic hexagonal ferrites and manganites, but here driven by the ordering of organic molecules in a metal - organic framework. our study reveals an extremely rich phase diagram with the prediction of topological domain walls, where the ferroelectricity arise from tripling the unit cells due to molecular ordering. wide domain walls with inner structure are predicted. | arxiv:2204.09546 |
a few years ago, bourgain proved that the centered hardy - littlewood maximal function for the cube has dimension free $ l ^ p $ - bounds for $ p > 1 $. we extend his result to products of euclidean balls of different dimensions. in addition, we provide dimension free $ l ^ p $ - bounds for the maximal function associated to products of euclidean spheres for $ p > \ frac { n } { n - 1 } $ and $ n \ ge 3 $, where $ n - 1 $ is the lowest occurring dimension of a single sphere. the aforementioned result is obtained from the latter one by applying the method of rotations from stein ' s pioneering work on the spherical maximal function. | arxiv:1703.07728 |
the gemini planet imager ( gpi ) contains a 10 - hole non - redundant mask ( nrm ), enabling interferometric resolution in complement to its coronagraphic capabilities. the nrm operates both in spectroscopic ( integral field spectrograph, henceforth ifs ) and polarimetric configurations. nrm observations were taken between 2013 and 2016 to characterize its performance. most observations were taken in spectroscopic mode with the goal of obtaining precise astrometry and spectroscopy of faint companions to bright stars. we find a clear correlation between residual wavefront error measured by the ao system and the contrast sensitivity by comparing phase errors in observations of the same source, taken on different dates. we find a typical 5 - $ \ sigma $ contrast sensitivity of $ 2 - 3 ~ \ times ~ 10 ^ { - 3 } $ at $ \ sim \ lambda / d $. we explore the accuracy of spectral extraction of secondary components of binary systems by recovering the signal from a simulated source injected into several datasets. we outline data reduction procedures unique to gpi ' s ifs and describe a newly public data pipeline used for the presented analyses. we demonstrate recovery of astrometry and spectroscopy of two known companions to hr 2690 and hd 142527. nrm + polarimetry observations achieve differential visibility precision of $ \ sigma \ sim0. 4 \ % $ in the best case. we discuss its limitations on gemini - s / gpi for resolving inner regions of protoplanetary disks and prospects for future upgrades. we summarize lessons learned in observing with nrm in spectroscopic and polarimetric modes. | arxiv:1904.09006 |
the main result of the paper is a new representation for the weyl lagrangian ( massless dirac lagrangian ). as the dynamical variable we use the coframe, i. e. an orthonormal tetrad of covector fields. we write down a simple lagrangian - wedge product of axial torsion with a lightlike element of the coframe - and show that this gives the weyl lagrangian up to a nonlinear change of dynamical variable. the advantage of our approach is that it does not require the use of spinors, pauli matrices or covariant differentiation. the only geometric concepts we use are those of a metric, differential form, wedge product and exterior derivative. our result assigns a variational meaning to the tetrad representation of the weyl equation suggested by j. b. griffiths and r. a. newing. | arxiv:0901.1070 |
parallel transport as dictated by a gauge field determines a collection of local reference systems. comparing local reference systems in overlapping regions leads to an ensemble of algebras of relational kinematical observables for gauge theories including general relativity. using an auxiliary cellular decomposition, we propose a discretization of the gauge field based on a decimation of the mentioned ensemble of kinematical observables. the outcome is a discrete ensemble of local subalgebras of ` ` macroscopic observables ' ' characterizing a measuring scale. a set of evaluations of those macroscopic observables is called an extended lattice gauge field because it determines a $ g $ - bundle over $ m $ ( and over submanifolds of $ m $ that inherit a cellular decomposition ) together with a lattice gauge field over an embedded lattice. a physical observable in our algebra of macroscopic observables is constructed. an initial study of aspects of regularization and coarse graining, which are special to this description of gauge fields over a combinatorial base, is presented. the physical relevance of this extension of ordinary lattice gauge fields is discussed in the context of quantum gravity. | arxiv:1905.04797 |
object tracking is a fundamental tool in modern innovation, with applications in defense systems, autonomous vehicles, and biomedical research. it enables precise identification, monitoring, and spatiotemporal analysis of objects across sequential frames, providing insights into dynamic behaviors. in cell biology, object tracking is vital for uncovering cellular mechanisms, such as migration, interactions, and responses to drugs or pathogens. these insights drive breakthroughs in understanding disease progression and therapeutic interventions. over time, object tracking methods have evolved from traditional feature - based approaches to advanced machine learning and deep learning frameworks. while classical methods are reliable in controlled settings, they struggle in complex environments with occlusions, variable lighting, and high object density. deep learning models address these challenges by delivering greater accuracy, adaptability, and robustness. this review categorizes object tracking techniques into traditional, statistical, feature - based, and machine learning paradigms, with a focus on biomedical applications. these methods are essential for tracking cells and subcellular structures, advancing our understanding of health and disease. key performance metrics, including accuracy, efficiency, and adaptability, are discussed. the paper explores limitations of current methods and highlights emerging trends to guide the development of next - generation tracking systems for biomedical research and broader scientific domains. | arxiv:2412.01119 |
the landscape of digital games is segregated by player ability. for example, sighted players have a multitude of highly visual games at their disposal, while blind players may choose from a variety of audio games. attempts at improving cross - ability access to any of those are often limited in the experience they provide, or disregard multiplayer experiences. we explore ability - based asymmetric roles as a design approach to create engaging and challenging mixed - ability play. our team designed and developed two collaborative testbed games exploring asymmetric interdependent roles. in a remote study with 13 mixed - visual - ability pairs we assessed how roles affected perceptions of engagement, competence, and autonomy, using a mixed - methods approach. the games provided an engaging and challenging experience, in which differences in visual ability were not limiting. our results underline how experiences unequal by design can give rise to an equitable joint experience. | arxiv:2101.05703 |
the 1950s are included. in 1942, isaac asimov started his foundation series, which chronicles the rise and fall of galactic empires and introduced psychohistory. the series was later awarded a one - time hugo award for " best all - time series ". theodore sturgeon ' s more than human ( 1953 ) explored possible future human evolution. in 1957, andromeda : a space - age tale by the russian writer and paleontologist ivan yefremov presented a view of a future interstellar communist civilization and is considered one of the most important soviet science fiction novels. in 1959, robert a. heinlein ' s starship troopers marked a departure from his earlier juvenile stories and novels. it is one of the first and most influential examples of military science fiction, and introduced the concept of powered armor exoskeletons. the german space opera series perry rhodan, written by various authors, started in 1961 with an account of the first moon landing and has since expanded in space to multiple universes, and in time by billions of years. it has become the most popular science fiction book series of all time. in the 1960s and 1970s, new wave science fiction was known for its embrace of a high degree of experimentation, both in form and in content, and a highbrow and self - consciously " literary " or " artistic " sensibility. in 1961, solaris by stanisław lem was published in poland. the novel dealt with the theme of human limitations as its characters attempted to study a seemingly intelligent ocean on a newly discovered planet. lem ' s work anticipated the creation of microrobots and micromachinery, nanotechnology, smartdust, virtual reality, and artificial intelligence ( including swarm intelligence ), as well as developing the ideas of " necroevolution " and the creation of artificial worlds. in 1965, dune by frank herbert featured a much more complex and detailed imagined future society than had previously in most science fiction. in 1967 anne mccaffrey began her dragonriders of pern science fantasy series. two of the novellas included in the first novel, dragonflight, made mccaffrey the first woman to win a hugo or nebula award. in 1968, philip k. dick ' s do androids dream of electric sheep? was published. it is the literary source of the blade runner movie franchise. in 1969, the left hand of darkness by ursula k. le guin was set on a planet in which the inhabitants have no fixed gender. it is one of the most influential | https://en.wikipedia.org/wiki/Science_fiction |
our understanding of the human connectome is fundamentally limited by the resolution of diffusion mr images. reconstructing a connectome ' s constituent neural pathways with tractography requires following a continuous field of fiber directions. typically, this field is found with simple trilinear interpolation in low - resolution, noisy diffusion mris. however, trilinear interpolation struggles following fine - scale changes in low - quality data. recent deep learning methods in super - resolving diffusion mris have focused on upsampling to a fixed spatial grid, but this does not satisfy tractography ' s need for a continuous field. in this work, we propose fenri, a novel method that learns spatially - continuous fiber orientation density functions from low - resolution diffusion - weighted images. to quantify fenri ' s capabilities in tractography, we also introduce an expanded simulated dataset built for evaluating deep - learning tractography models. we demonstrate that fenri accurately predicts high - resolution fiber orientations from realistic low - quality data, and that fenri - based tractography offers improved streamline reconstruction over the current use of trilinear interpolation. | arxiv:2312.05721 |
the generalized number - theoretic transformation ( npt ) is formulated on the basis of the exponential function theorem, which allows us to replace operations modulo the expression as a whole by modulo operations on the exponent of this function, which makes this theorem fundamental for npt, since it is such a function used in npt as a weight conversion function. on the basis of this theorem, all the main theorems of the generalized npt, their duality, as well as the properties of the weight functions of this transformation are formulated and proved. the choice of the basis of this function, as which any number can be chosen, including a complex one, determines not only one or another type of transformation, but also the module of the transformation itself. this allows us to generalize a number of well - known npts, such as mersen, gauss, and even fourier, in the form of a unified theory of discrete transformations. | arxiv:2011.11039 |
in this paper we demonstrate that radiation patterns could cause flow - like behaviour without any reference to hydrodynamic description. for that purpose we use a statistical ensemble of radiating dipoles, motivated by the investigation of the equivalent photon yield produced by decelerating charges. for the elliptic asymmetry factor we find a reasonable agreement with experimental data. | arxiv:1503.06628 |
we present the observation of a transverse thermopower, or planar nernst effect, in patterned ultrathin film ( 8 nm ) of la0. 7sr0. 3mno3 ( lsmo ) driven by heat current applied in - plane of the film and planar hall effect ( phe ) in the same lsmo ultrathin film with in - plane current of 100 microa is also investigated. even for temperature difference of 5 k the planar nernst effect in ultrathin film ( 8 nm ) shows a coercivity of 3 oe same as observed in planar hall effect measurement and confirms the ferromagnetic nature of thin film. the angular dependence of transverse voltages shows four - fold sin { theta } cos { theta } dependence symmetry at 250 k, which is consistent with planar hall effect measurement. | arxiv:1501.06138 |
we discuss both the uv and ir origin of the one - loop triangle gauge anomalies for noncommutative nonabelian chiral gauge theories with fundamental, adjoint and bi - fundamental fermions for u ( n ) groups. we find that gauge anomalies only come from planar triangle diagrams, the non - planar triangle contributions giving rise to no breaking of the ward identies. generally speaking, theories with fundamental and bi - fundamental chiral matter are anomalous. theories with only adjoint chiral fermions are anomaly free. | arxiv:hep-th/0008126 |
in these proceedings i briefly : ( 1 ) review the impact ( or " feedback " ) that active galactic nuclei ( agn ) are predicted to have on their host galaxies and larger scale environment, ( 2 ) review the observational evidence for or against these predictions and ( 3 ) present new results on ionised outflows in agn. the observational support for the " maintenance mode " of feedback is strong ( caveat the details ) ; agn at the centre of massive halos appear to be regulating the cooling of hot gas, which could in turn control the levels of future star formation ( sf ) and black hole growth. in contrast, direct observational support for more rapid forms of feedback, which dramatically impact on sf ( i. e., the " quasar mode " ), remains elusive. from a systematic study of the spectra of approx. 24000 z < 0. 4 agn we find that extreme ionised gas kinematics are common, and are most prevalent in radio bright agn ( l [ 1. 4ghz ] > 10 ^ 23 w / hz ). follow - up ifu observations have shown that these extreme gas kinematics are extended over kilo - parsec scales. however, the co - existence of high - levels of sf, luminous agn activity and radio jets raises interesting questions on the primary drivers and impact of these outflows. galaxy - wide, high - mass outflows are being observed in an increasing number of agn and are a plausible mechanism for the depletion of gas ; however, there is still much work to be done to determine the physical processes that drive these outflows and to measure the level of impact that they have on their host galaxies. | arxiv:1312.3609 |
the present paper presents two new approaches to fourier series and spectral analysis of singular measures. | arxiv:1712.07267 |
we calculate the ground - state two - spin correlation functions of spin - 1 / 2 quantum heisenberg chains with random exchange couplings using the real - space renormalization group scheme. we extend the conventional scheme to take account of the contribution of local higher multiplet excitations in each decimation step. this extended scheme can provide highly accurate numerical data for large systems. the random average of staggered spin correlations of the chains with random antiferromagnetic ( af ) couplings shows algebraic decay like $ 1 / r ^ 2 $, which verifies the fisher ' s analytic results. for chains with random ferromagnetic ( fm ) and af couplings, the random average of generalized staggered correlations is found to decay more slowly than a power - law, in the form close to $ 1 / \ ln ( r ) $. the difference between the distribution functions of the spin correlations of the random af chains and of the random fm - af chains is also discussed. | arxiv:cond-mat/9905352 |
the effect of a strongly magnetized cold plasma on the compton - like photoproduction of a neutrino - antineutrino pair on an electron, $ \ gamma e \ to e \ nu \ bar \ nu $, has been considered. the contribution of this process to the neutrino emissivity in both the non - resonance and the resonance cases has been calculated with taking account of the photon dispersion properties in medium. our results show that the neutrino emissivity owing to the $ \ gamma e \ to e \ nu \ bar \ nu $ reaction is significantly modified as compared to the previously reported data. | arxiv:1410.5566 |
a classical 3 - d thermoviscoelastic system of kelvin - voigt type is considered. the existence and uniqueness of a global regular solution is proved without small data assumption. the existence proof is based on the successive approximation method. the crucial part constitute a priori estimates on an arbitrary finite time interval, which are derived with the help of the theory of anisotropic sobolev spaces with a mixed norm. | arxiv:1112.3176 |
direct search methods are a class of popular global optimization algorithms for general nonconvex programs. in this paper, we propose a randomized directional search algorithm ( rdsa ) for globally solving nonconvex optimization problems. the convergence of rdsa to a global optimizer is established and its computational complexity is derived. additionally, irdsa is proposed as an improved algorithm of rdsa. we then apply both rdsa and irdsa to nonconvex programs with multiple local optima. results demonstrate that rdsa and irdsa exhibit remarkable efficacy to identify the global optimum and outperform other global optimization algorithms in terms of accuracy, efficiency, and robustness. | arxiv:2501.00469 |
for the detection of fire - like targets in indoor, outdoor and forest fire images, as well as fire detection under different natural lights, an improved yolov5 fire detection deep learning algorithm is proposed. the yolov5 detection model expands the feature extraction network from three dimensions, which enhances feature propagation of fire small targets identification, improves network performance, and reduces model parameters. furthermore, through the promotion of the feature pyramid, the top - performing prediction box is obtained. fire - yolov5 attains excellent results compared to state - of - the - art object detection networks, notably in the detection of small targets of fire and smoke with map 90. 5 % and f1 score 88 %. overall, the fire - yolov5 detection model can effectively deal with the inspection of small fire targets, as well as fire - like and smoke - like objects with f1 score 0. 88. when the input image size is 416 x 416 resolution, the average detection time is 0. 12 s per frame, which can provide real - time forest fire detection. moreover, the algorithm proposed in this paper can also be applied to small target detection under other complicated situations. the proposed system shows an improved approach in all fire detection metrics such as precision, recall, and mean average precision. | arxiv:2310.06351 |
text - to - video models have made remarkable advancements through optimization on high - quality text - video pairs, where the textual prompts play a pivotal role in determining quality of output videos. however, achieving the desired output often entails multiple revisions and iterative inference to refine user - provided prompts. current automatic methods for refining prompts encounter challenges such as modality - inconsistency, cost - discrepancy, and model - unaware when applied to text - to - video diffusion models. to address these problem, we introduce an llm - based prompt adaptation framework, termed as prompt - a - video, which excels in crafting video - centric, labor - free and preference - aligned prompts tailored to specific video diffusion model. our approach involves a meticulously crafted two - stage optimization and alignment system. initially, we conduct a reward - guided prompt evolution pipeline to automatically create optimal prompts pool and leverage them for supervised fine - tuning ( sft ) of the llm. then multi - dimensional rewards are employed to generate pairwise data for the sft model, followed by the direct preference optimization ( dpo ) algorithm to further facilitate preference alignment. through extensive experimentation and comparative analyses, we validate the effectiveness of prompt - a - video across diverse generation models, highlighting its potential to push the boundaries of video generation. | arxiv:2412.15156 |
the mouse is one of the most studied animal models in the field of systems neuroscience. understanding the generalized patterns and decoding the neural representations that are evoked by the diverse range of natural scene stimuli in the mouse visual cortex is one of the key quests in computational vision. in recent years, significant parallels have been drawn between the primate visual cortex and hierarchical deep neural networks. however, their generalized efficacy in understanding mouse vision has been limited. in this study, we investigate the functional alignment between the mouse visual cortex and deep learning models for object classification tasks. we first introduce a generalized representational learning strategy that uncovers a striking resemblance between the functional mapping of the mouse visual cortex and high - performing deep learning models on both top - down ( population - level ) and bottom - up ( single cell - level ) scenarios. next, this representational similarity across the two systems is further enhanced by the addition of neural response normalization ( neurn ) layer, inspired by the activation profile of excitatory and inhibitory neurons in the visual cortex. to test the performance effect of neurn on real - world tasks, we integrate it into deep learning models and observe significant improvements in their robustness against data shifts in domain generalization tasks. our work proposes a novel framework for comparing the functional architecture of the mouse visual cortex with deep learning models. our findings carry broad implications for the development of advanced ai models that draw inspiration from the mouse visual cortex, suggesting that these models serve as valuable tools for studying the neural representations of the mouse visual cortex and, as a result, enhancing their performance on real - world tasks. | arxiv:2505.06886 |
in - context learning has shown great success in i. i. d semantic parsing splits, where the training and test sets are drawn from the same distribution. in this setup, models are typically prompted with demonstrations that are similar to the input utterance. however, in the setup of compositional generalization, where models are tested on outputs with structures that are absent from the training set, selecting similar demonstrations is insufficient, as often no example will be similar enough to the input. in this work, we propose a method to select diverse demonstrations that aims to collectively cover all of the structures required in the output program, in order to encourage the model to generalize to new structures from these demonstrations. we empirically show that combining diverse demonstrations with in - context learning substantially improves performance across three compositional generalization semantic parsing datasets in the pure in - context learning setup and when combined with finetuning. | arxiv:2212.06800 |
we present experimental investigation on the fluorescence profiles observed by excitation of the hyperfine transitions of the second resonance line of potassium with a wavelength of 404. 4 nm in dependence on the atomic density. this leads to both direct decay of the excited level population to the ground state ( violet fluorescence ), and to cascade decay via the first resonance lines ( infrared fluorescence ). it has been shown that the behavior of these two fluorescence profiles is different : increasing the atomic density, the violet fluorescence profile exhibits a well - pronounced self - absorption dip, while the infrared line does not show any narrow - width reduced absorption structure. moreover, the profiles of the infrared line have a higher signal - to - noise ratio than that of the violet line. our investigations show that beside atomic population, atomic polarization is also transferred by the cascade transitions. this is evidenced by registration of coherent magneto - optical resonances at the two fluorescence lines. the signal - to - noise ratio of these resonances registered at the first resonance line is significantly higher than at those obtained at the second resonance line. the proposed study makes it possible to examine cascade transitions in alkali atoms, particularly the preservation of atomic polarization, i. e. the coherence transfer by cascade transitions. | arxiv:1804.06762 |
various nuclear structure observables are evaluated employing low - momentum nucleon - nucleon ( nn ) potentials $ v _ { \ rm low - k } $ derived from the cd - bonn and nijmegen nn interactions $ v _ { nn } $. by construction, the high momentum modes of the original $ v _ { nn } $ are integrated out in $ v _ { \ rm low - k } $, with the requirement that the deuteron binding energy and low energy phase shifts of $ v _ { nn } $ are exactly reproduced. using this interaction, we evaluate the bulk properties ( binding energy and saturation density ) of nuclear matter and finite nuclei, in particular their dependence on the cut - off parameter. we also study the pairing gap and the residual interaction in nuclear matter in terms of the landau parametrization. at low and medium densities, the hf and bhf binding energies for nuclear matter calculated with the $ v _ { \ rm low - k } $ ' s derived from the cd - bonn and nijmegen potentials are nearly identical. the pairing gaps and landau parameters derived from $ v _ { \ rm low - k } $ are remarkably close to those given by the full - space $ v _ { nn } $. the $ v _ { \ rm low - k } $ interactions, however, fail to reproduce the saturation property of nuclear matter at higher densities if the cut - off for the high momentum modes is assumed density independent. | arxiv:nucl-th/0210010 |
using the cosmic origins spectrograph ( cos ) on the hubble space telescope ( hst ) the cos science team has conducted a high signal - to - noise survey of 14 bright qsos. in a previous paper ( savage et al. 2014 ) these far - uv spectra were used to discover 14 " warm " ( $ t > 10 ^ 5 $ k ) absorbers using a combination of broad ly \ alpha \ and o vi absorptions. a reanalysis of a few of this new class of absorbers using slightly relaxed fitting criteria finds as many as 20 warm absorbers could be present in this sample. a shallow, wide spectroscopic galaxy redshift survey has been conducted around these sight lines to investigate the warm absorber environment, which is found to be spiral - rich galaxy groups or cluster outskirts with radial velocity dispersions of \ sigma \ = 250 - 750 km / s. while 2 \ sigma \ evidence is presented favoring the hypothesis that these absorptions are associated with the galaxy groups and not with the individual, nearest galaxies, this evidence has considerable systematic uncertainties and is based on a small sample size so it is not entirely conclusive. if the associations are with galaxy groups, the observed frequency of warm absorbers ( dn / dz = 3. 5 - 5 per unit redshift ) requires them to be very large ( ~ 1 mpc in radius at high covering factor ). most likely these warm absorbers are interface gas clouds whose presence implies the existence of a hotter ( $ t \ sim 10 ^ { 6. 5 } $ k ), diffuse and probably very massive ( $ > 10 ^ { 11 } ~ m _ { \ odot } $ ) intra - group medium which has yet to be detected directly. | arxiv:1405.4307 |
extending recent work in 5 dimensions, we prove the existence and uniqueness of solutions to the reduced einstein equations for vacuum black holes in $ ( n + 3 ) $ - dimensional spacetimes admitting the isometry group $ \ mathbb { r } \ times u ( 1 ) ^ { n } $, with kaluza - klein asymptotics for $ n \ geq3 $. this is equivalent to establishing existence and uniqueness for singular harmonic maps $ \ varphi : \ mathbb { r } ^ 3 \ setminus \ gamma \ rightarrow sl ( n + 1, \ mathbb { r } ) / so ( n + 1 ) $ with prescribed blow - up along $ \ gamma $, a subset of the $ z $ - axis in $ \ mathbb { r } ^ 3 $. we also analyze the topology of the domain of outer communication for these spacetimes, by developing an appropriate generalization of the plumbing construction used in the lower dimensional case. furthermore, we provide a counterexample to a conjecture of hollands - ishibashi concerning the topological classification of the domain of outer communication. a refined version of the conjecture is then presented and established in spacetime dimensions less than 8. | arxiv:2203.08325 |
this paper addresses the challenges of mining latent patterns and modeling contextual dependencies in complex sequence data. a sequence pattern mining algorithm is proposed by integrating bidirectional long short - term memory ( bilstm ) with a multi - scale attention mechanism. the bilstm captures both forward and backward dependencies in sequences, enhancing the model ' s ability to perceive global contextual structures. at the same time, the multi - scale attention module assigns adaptive weights to key feature regions under different window sizes. this improves the model ' s responsiveness to both local and global important information. extensive experiments are conducted on a publicly available multivariate time series dataset. the proposed model is compared with several mainstream sequence modeling methods. results show that it outperforms existing models in terms of accuracy, precision, and recall. this confirms the effectiveness and robustness of the proposed architecture in complex pattern recognition tasks. further ablation studies and sensitivity analyses are carried out to investigate the effects of attention scale and input sequence length on model performance. these results provide empirical support for structural optimization of the model. | arxiv:2504.15223 |
the burling sequence is a sequence of triangle - free graphs of increasing chromatic number. each of them is isomorphic to the intersection graph of a set of axis - parallel boxes in $ r ^ 3 $. these graphs were also proved to have other geometrical representations : intersection graphs of line segments in the plane, and intersection graphs of frames, where a frame is the boundary of an axis - aligned rectangle in the plane. we call burling graph every graph that is an induced subgraph of some graph in the burling sequence. we give five new equivalent ways to define burling graphs. three of them are geometrical, one is of a more graph - theoretical flavour and one is more axiomatic. | arxiv:2104.07001 |
we propose a novel approach for generating region proposals for performing face - detection. instead of classifying anchor boxes using features from a pixel in the convolutional feature map, we adopt a pooling - based approach for generating region proposals. however, pooling hundreds of thousands of anchors which are evaluated for generating proposals becomes a computational bottleneck during inference. to this end, an efficient anchor placement strategy for reducing the number of anchor - boxes is proposed. we then show that proposals generated by our network ( floating anchor region proposal network, fa - rpn ) are better than rpn for generating region proposals for face detection. we discuss several beneficial features of fa - rpn proposals like iterative refinement, placement of fractional anchors and changing anchors which can be enabled without making any changes to the trained model. our face detector based on fa - rpn obtains 89. 4 % map with a resnet - 50 backbone on the wider dataset. | arxiv:1812.05586 |
we analyzed the band splitting of a type ii radio burst observed on 1997 may 12 by ground - and space - based radio spectrometers. type ii radio emission is the most evident signature of coronal shock waves and the observed band splitting is generally interpreted as due to plasma emission from both upstream and downstream shock regions. from the inferred compression ratio we estimated, using the magnetohydrodynamic ( mhd ) rankine - hugoniot relations, the ambient alfven mach number. by means of the electron density obtained by inverting white - light polarized brightness ( pb ) coronagraph data and the shock speed inferred from the type ii frequency drift, we finally derived a radial profile for the magnetic field strength in the middle corona. the result was compared with the field profile obtained in may 1997 ( but above $ \ sim 5 r _ { sun } $ ) with faraday rotation measurements of extragalactic radio sources occulted by the corona. the power law of the form $ b ( r ) $ = 3. 76 $ r ^ { - 2. 29 } $ gauss inferred in that work nicely describes the combined set of data in a wide range of heliocentric distances ( $ r $ $ \ sim $ 1. 8 - 14 $ r _ { sun } $ ). | arxiv:1311.0037 |
in this work, we revisit well - studied problems of fair allocation of indivisible items among agents with general, non - monotone valuations. we explore the existence and efficient computation of allocations that satisfy either fairness or equity constraints. the fairness notions we consider ensure that each agent values her bundle at least as much as others ', allowing for ( any or some ) item removal, while the equity guarantees roughly equal valuations among agents, with similar adjustments. for objective valuations where items are classified as either goods or chores, we present a pseudo - polynomial local - search algorithm computing an ` ` equitable - up - to - any - good - or - any - chore ' ' ( eqx * ) allocation, a weaker version of an ` ` equitable - up - to - any - item " ( eqx ) allocation. additionally, we provide a polynomial - time greedy algorithm that computes an ` ` equitable - up - to - one - item " ( eq1 ) allocation, and a similar algorithm returning an eqx * allocation when the valuations are also additive. as a key technical contribution of this work, by leveraging fixed - point theorems ( such as sperner ' s lemma and its variants ), we establish the existence of ` ` equitable - up - to - one - good - and - one - chore ' ' ( eq1 * ) and ` ` envy - free - up - to - one - good - and - one - chore ' ' ( ef1 * ) allocations for non - negative ( and possibly non - objective and non - monotone ) valuations. this holds even when items are arranged in a path and bundles must form connected sub - paths. additionally, we present a polynomial - time dynamic - programming algorithm that computes an eq1 * allocation. finally, we extend the ef1 * and eq1 * results to non - positive valuations using a novel multi - coloring variant of sperner ' s lemma, a combinatorial result of independent interest. for monotone non - increasing valuations and path - connected bundles, this implies the existence of ef1 and eq1 allocations, with eq1 allocations being efficiently computable. | arxiv:2503.05695 |
we report the results of experiments that examined the dependence of the dripping dynamics of a leaky faucet on the orifice diameter. the transition of the dripping frequency between periodic and chaotic states was found to depend on the orifice diameter. we suggest a theoretical explanation for these transitions based on drop formation time scales. in addition, short - range anti - correlations were measured in the chaotic region. these too showed a dependence on the faucet diameter. finally, a comparison was done between the experimental results with a one - dimensional model for drop formation. quantitative agreement was found between the simulations and the experimental results. | arxiv:physics/0602101 |
with increasing complexity of automated driving systems ( ads ), ensuring their safety and reliability has become a critical challenge. the verification and validation ( v & v ) of these systems are particularly demanding when ai components are employed to implement perception and / or control functions. in esa - funded project vivas, we developed a generic framework for system - level simulation - based v & v of autonomous systems. the approach is based on a simulation model of the system, an abstract model that describes symbolically the system behavior, and formal methods to generate scenarios and verify the simulation executions. various coverage criteria can be defined to guide the automated generation of the scenarios. in this paper, we describe the instantiation of the vivas framework for an ads case study. this is based on the integration of carla, a widely - used driving simulator, and its scenariorunner tool, which enables the creation of diverse and complex driving scenarios. this is also used in the carla autonomous driving challenge to validate different ads agents for perception and control based on ai, shared by the carla community. we describe the development of an abstract ads model and the formulation of a coverage criterion that focuses on the behaviors of vehicles relative to the vehicle with ads under verification. leveraging the vivas framework, we generate and execute various driving scenarios, thus testing the capabilities of the ai components. the results show the effectiveness of vivas in automatically generating scenarios for system - level simulation - based v & v of an automated driving system using carla and scenariorunner. therefore, they highlight the potential of the approach as a powerful tool in the future of ads v & v methodologies. | arxiv:2311.09784 |
we present a method for reading digital data embedded in planar 3d printed surfaces. the data are organised in binary arrays and embedded as surface textures in a way inspired by qr codes. at the core of the retrieval method lies a convolutional neural network, outputting a confidence map of the location of the surface textures encoding value 1 bits. subsequently, the bit array is retrieved through a series of simple image processing and statistical operations applied on the confidence map. extensive experimentation with images captured from various camera views, under various illumination conditions and from objects printed with various material colours, shows that the proposed method generalizes well and achieves the level of accuracy required in practical applications. | arxiv:1811.07640 |
unlike trojans, horseshoe coorbitals are not generally considered to be long - term stable ( dermott and murray, 1981 ; murray and dermott, 1999 ). as the lifetime of earth ' s and venus ' s horseshoe coorbitals is expected to be about a gyr, we investigated the possible contribution of late - escaping inner planet coorbitals to the lunar late heavy bombardment. contrary to analytical estimates, we do not find many horseshoe objects escaping after first 100 myr. in order to understand this behaviour, we ran a second set of simulations featuring idealized planets on circular orbits with a range of masses. we find that horseshoe coorbitals are generally long lived ( and potentially stable ) for systems with primary - to - secondary mass ratios larger than about 1200. this is consistent with results of laughlin and chambers ( 2002 ) for equal - mass pairs or coorbital planets and the instability of jupiter ' s horseshoe companions ( stacey and connors, 2008 ). horseshoe orbits at smaller mass ratios are unstable because they must approach within 5 hill radii of the secondary. in contrast, tadpole orbits are more robust and can remain stable even when approaching within 4 hill radii of the secondary. | arxiv:1206.1888 |
we prove the uniqueness of solutions to the dafermos regularization viscous wave fan profiles for riemann solutions of scalar hyperbolic conservation laws. we emphasize that our results are not restricted to the small self - similar viscosity regime. we rely on suitable adaptations of serrin ' s sweeping principle and the sliding method from the qualitative theory of semilinear elliptic pdes. in order to illustrate the delicacy of our result, we prove the existence of an unbounded solution in the case of burgers equation. lastly, we can combine aspects of these results in order to give a precise description of the dafermos regularization of rarefaction waves of burgers equation. | arxiv:2303.06713 |
the position - sensitive detector ( psd ) for photometrical and spectral observation on the 6 - meter optical telescope of the special astrophysical observatory ( russia ) is described. the psd consists of a position - sensitive tube, amplifiers of output signals, analog - to - digital converters ( adc ) and a digital logic plate, which produces a signal for adc start and an external strob pulse for reading information by registration system. if necessary, the thermoelectric cooler can be used. the position - sensitive tube has the following main elements : a photocathode, electrodes of inverting optics, a block of microchannel plates ( mcp ) and a position - sensitive collector of quadrant type. the main parameters of the psd are the diameter of the sensitive surface is 25 mm, the spatial resolution is better than 100 ( \ mu ) m in the centre and a little worse on the periphery ; the dead time is near 0. 5 ( \ mu ) s ; the detection quantum efficiency is defined by the photocathode and it is not less than 0. 1, as a rule ; dark current is about hundreds of cps, or less, when cooling. psd spectral sensitivity depends on the type of photocathode and input window material. we use a multialkali photocathode and a fiber or uv - glass, which gives the short - wave cut of 360 nm or 250 nm, respectively. | arxiv:astro-ph/0310353 |
\ xi _ b ^ 0 ) = 4. 7 \ pm4. 7 ( stat ) \ pm0. 7 ( syst ) $ mev / $ c ^ 2 $. the isospin splitting of the $ \ xi _ c ^ { 0, + } $ states is found to be $ m ( \ xi _ c ^ 0 ) - m ( \ xi _ c ^ + ) $ = $ 2. 85 \ pm0. 30 ( stat ) \ pm0. 04 ( syst ) $ mev / $ c ^ 2 $. the following lifetime measurements are made : \ begin { eqnarray } \ tau ( \ lambda _ b ) = 1. 565 \ pm0. 035 ( stat ) \ pm0. 020 ( syst ) \, ps, \ nonumber \ \ \ tau ( \ xi _ b ^ - ) = 1. 32 \ pm0. 14 ( stat ) \ pm0. 02 ( syst ) \, ps, \ nonumber \ \ \ tau ( \ omega _ b ^ - ) = 1. 66 ^ { + 0. 53 } _ { - 0. 40 } ( stat ) \ pm0. 02 ( syst ) \, ps. \ nonumber \ end { eqnarray } | arxiv:1403.8126 |
the p4 programming language offers high - level, declarative abstractions that bring the flexibility of software to the domain of networking. unfortunately, the main abstraction used to represent packet data in p4, namely header types, lacks basic safety guarantees. over the last few years, experience with an increasing number of programs has shown the risks of the unsafe approach, which often leads to subtle software bugs. this paper proposes safep4, a domain - specific language for programmable data planes in which all packet data is guaranteed to have a well - defined meaning and satisfy essential safety guarantees. we equip safep4 with a formal semantics and a static type system that statically guarantees header validity - - - a common source of safety bugs according to our analysis of real - world p4 programs. statically ensuring header validity is challenging because the set of valid headers can be modified at runtime, making it a dynamic program property. our type system achieves static safety by using a form of path - sensitive reasoning that tracks dynamic information from conditional statements, routing tables, and the control plane. our evaluation shows that safep4 ' s type system can effectively eliminate common failures in many real - world programs. | arxiv:1906.07223 |
using tunneling spectroscopy, we have measured the local electron energy distribution function in the normal part of a superconductor - normal metal - superconductor ( sns ) josephson junction containing an extra lead to a normal reservoir. in the presence of simultaneous supercurrent and injected quasiparticle current, the distribution function exhibits a sharp feature at very low energy. the feature is odd in energy, and odd under reversal of either the supercurrent or the quasiparticle current direction. the feature represents an effective temperature gradient across the sns josephson junction that is controllable by the supercurrent. | arxiv:cond-mat/0601488 |
the fisher and geks are celebrated as ideal bilateral and multilateral indexes due to their superior axiomatic and econ - theoretic properties. the fisher index is the main index used for constructing cpi by statistical agencies and the geks is the index used for compiling ppps in world bank ' s international comparison program ( icp ). despite such a high status and the importance attached to these indexes, the stochastic approach to these indexes is not well - developed and no measures of reliability exist for these important economic statistics. the main objective of this paper is to fill this gap. we show how appropriate reliability measures for the fisher and geks indexes, and other ideal price index numbers can be derived and how they should be interpreted and used in practice. in an application to 2017 icp data on a sample of 173 countries, we estimate the fisher and geks indexes along with their reliability measures, make comparisons with several other notable indexes and discuss the implications. | arxiv:2210.13684 |
adaptive designs have been proposed for clinical trials in which the nuisance parameters or alternative of interest are unknown or likely to be misspecified before the trial. whereas most previous works on adaptive designs and mid - course sample size re - estimation have focused on two - stage or group sequential designs in the normal case, we consider here a new approach that involves at most three stages and is developed in the general framework of multiparameter exponential families. not only does this approach maintain the prescribed type i error probability, but it also provides a simple but asymptotically efficient sequential test whose finite - sample performance, measured in terms of the expected sample size and power functions, is shown to be comparable to the optimal sequential design, determined by dynamic programming, in the simplified normal mean case with known variance and prespecified alternative, and superior to the existing two - stage designs and also to adaptive group sequential designs when the alternative or nuisance parameters are unknown or misspecified. | arxiv:1105.3280 |
continual learning ( cl ) is designed to learn new tasks while preserving existing knowledge. replaying samples from earlier tasks has proven to be an effective method to mitigate the forgetting of previously acquired knowledge. however, the current research on the training efficiency of rehearsal - based methods is insufficient, which limits the practical application of cl systems in resource - limited scenarios. the human visual system ( hvs ) exhibits varying sensitivities to different frequency components, enabling the efficient elimination of visually redundant information. inspired by hvs, we propose a novel framework called continual learning in the frequency domain ( clfd ). to our knowledge, this is the first study to utilize frequency domain features to enhance the performance and efficiency of cl training on edge devices. for the input features of the feature extractor, clfd employs wavelet transform to map the original input image into the frequency domain, thereby effectively reducing the size of input feature maps. regarding the output features of the feature extractor, clfd selectively utilizes output features for distinct classes for classification, thereby balancing the reusability and interference of output features based on the frequency domain similarity of the classes across various tasks. optimizing only the input and output features of the feature extractor allows for seamless integration of clfd with various rehearsal - based methods. extensive experiments conducted in both cloud and edge environments demonstrate that clfd consistently improves the performance of state - of - the - art ( sota ) methods in both precision and training efficiency. specifically, clfd can increase the accuracy of the sota cl method by up to 6. 83 % and reduce the training time by 2. 6 $ \ times $. | arxiv:2410.06645 |
the proper motion measurements for 143 previously known l and t dwarfs are presented. from this sample we identify and discuss 8 high velocity l dwarfs. we also find 4 new wide common proper motion binaries / multiple systems. using the moving cluster methods we have also identified a number of l dwarfs that may be members of the ursa major ( age ~ 400 myr ), the hyades ( age ~ 625 myr ) and the pleiades ( age ~ 125 myr ) moving groups. | arxiv:0710.4786 |
we investigate the use of a split - ring resonator ( srr ) incorporated with an atomic - vapor cell to improve the sensitivity and the minimal detectable electric ( e ) field of rydberg atom - based sensors. in this approach, a sub - wavelength srr is placed around an atomic vapor - cell filled with cesium atoms for e - field measurements at 1. 3 ~ ghz. the srr provides a factor of 100 in the enhancement of the e - field measurement sensitivity. using electromagnetically induced transparency ( eit ) with aulter - townes splitting, e - field measurements down to 5 ~ mv / m are demonstrated with the srr, while in the absence of the srr, the minimal detectable field is 500 ~ mv / m. we demonstrate that by combining eit with a heterodyne rydberg atom - based mixer approach, the srr allows for the a sensitivity of 5. 5 ~ $ \ mu $ v / m $ \ sqrt { { \ rm hz } } $, which is two - orders of magnitude improvement in sensitivity than when the srr is not used. | arxiv:2202.08954 |
we study the dynamics of a two - level system driven by an off - resonant few - cycle pulse which has a phase jump $ \ phi $ at $ t = t _ { 0 } $, in contrast to many cycle pulses, under non rotating - wave approximation ( nrwa ). we give a closed form analytical solution for the evolution of the probability amplitude $ | c _ { a } ( t ) | $ for the upper level. using the appropriate pulse parameters like phase - jump $ \ phi $, jump time $ t _ { 0 } $, pulse width $ \ tau $, frequency $ \ nu $ and rabi frequency $ \ omega _ { 0 } $ the population transfer, after the pulse is gone, can be optimized and for the pulse considered here, enhancement of $ 10 ^ { 6 } - 10 ^ { 8 } $ factor was obtained. | arxiv:1010.0138 |
this study describes the dynamics of covid - 19 deaths and infections via a monte carlo approach. the analyses include death ' s data from usa, brazil, mexico, uk, india and russia, which comprise the four countries with the highest number of deaths / confirmed cases, as of aug 07, 2020, according to the who. the gompertz functions were fitted to the data of weekly averaged confirmed deaths per day by mapping the $ \ chi ^ 2 $ values. the uncertainties, variances and covariances of the model parameters were calculated by propagation. the fitted functions for the average deaths per day for usa and india have an upward trend, with the former having a higher growth rate and quite huge uncertainties. for mexico, uk and russia, the fits are consistent with a slope down pattern. for brazil we found a subtle trend down, but with significant uncertainties. the usa, uk and india data shown a first peak with a higher growth rate when compared to the second one, demonstrating the benefits of non - pharmaceutical interventions of sanitary measures and social distance flattening the curve. for usa, a third peak seems quite plausible, most likely related with the recent relaxation policies. brazil ' s data are satisfactorily described by two highly overlapped gompertz functions with similar growth rates, suggesting a two - steps process for the pandemic spreading. the 95 % ci for the total number of deaths ( $ \ times 10 ^ 3 $ ) predicted by the model for aug 31, 2020 are 160 to 220, 110 to 130, 59 to 62, 46. 6 to 47. 3, 54 to 63 and 16. 0 to 16. 7 for usa, brazil, mexico, uk, india and russia, respectively. our estimates for the prevalences of infections are in reasonable agreement with some preliminary reports from serological studies carried out in usa and brazil. the method represents an effective framework to estimate the line - shape of the infection curves and the uncertainties of the relevant parameters based on the actual data. | arxiv:2008.04989 |
the weak - coupling renormalization group method is an asymptotically exact method to find superconducting instabilities of a lattice model of correlated electrons. here we extend it to spin - orbit coupled lattice systems and study the emerging superconducting phases of the rashba - hubbard model. since rashba type spin - orbit coupling breaks inversion symmetry, the arising superconducting phases may be a mixture of spin - singlet and spin - triplet states. we study the two - dimensional square lattice as a paradigm and discuss the symmetry properties of the arising spin - orbit coupled superconducting states including helical spin - triplet superconductivity. we also discuss how to best deal with split energy bands within a method which restricts paired electrons to momenta on the fermi surface. | arxiv:2004.12624 |
for classical knots, it is well known that their determinants mod $ 8 $ are classified by the arf invariant. boden and karimi introduced a determinant of checkerboard colorable virtual knots. we prove that their determinant mod $ 8 $ is classified by the coefficient of $ z ^ 2 $ in the ascending polynomial which is an extension of the conway polynomial for classical knots. | arxiv:2408.01891 |
we consider the stochastic allen - cahn equation driven by mollified space - time white noise. we show that, as the mollifier is removed, the solutions converge weakly to 0, independently of the initial condition. if the intensity of the noise simultaneously converges to 0 at a sufficiently fast rate, then the solutions converge to those of the deterministic equation. at the critical rate, the limiting solution is still deterministic, but it exhibits an additional damping term. | arxiv:1201.3089 |
we consider the general properties of the replicator dynamical system from the standpoint of its evolution and stability. vector field analysis as well as spectral properties of such system has been studied. lyaponuv function for investigation of system evolution has been proposed. the generalization of the replicator dynamics for the case of multi - agent systems has been introduced. we propose a new mathematical model to describe the multi - agent interaction in complex system. | arxiv:cond-mat/0302493 |
we consider a hydrodynamic model of flocking - type with all - to - all interaction kernel in one - space dimension and establish global existence of entropy weak solutions with concentration to the cauchy problem for any bv initial data that has finite total mass confined in a bounded interval and initial density uniformly positive therein. in addition, under a suitable condition on the initial data, we show that entropy weak solutions with concentration admit time - asymptotic flocking. | arxiv:2104.14573 |
solar energetic particles ( seps ) in the energy range 10s kev / nucleon - 100s mev / nucleon originate from sun. their high flux near earth may damage the space borne electronics and generate secondary radiations harmful for the life on earth and thus understanding their energization on sun is important for space weather prediction. impulsive ( or $ { } ^ { 3 } $ he - rich ) sep events are associated with the acceleration of charge particles in solar flares by magnetic reconnection and related processes. the preferential acceleration of heavy ions and the extra - ordinary abundance enhancement of $ { } ^ 3 $ he in the impulsive sep events are not understood yet. in this paper, we study ion acceleration in magnetic reconnection by two dimensional hybrid - kinetic plasma simulations ( kinetic ions and inertial electron fluid ). all the ions species are treated self - consistently in our simulations. we find that heavy ions are preferentially accelerated to energies many times larger than their initial thermal energies by a variety of acceleration mechanisms operating in reconnection. most efficient acceleration takes place in the flux pileup regions of magnetic reconnection. heavy ions with sufficiently small values of charge to mass ratio ( $ q / m $ ) can be accelerated by pickup mechanism in outflow regions even before any magnetic flux is piled up. the energy spectra of heavy ions develop a shoulder like region, a non - thermal feature, as a result of the acceleration. the spectral index of the power law fit to the shoulder region of the spectra varies approximately as $ ( q / m ) ^ { - 0. 64 } $. abundance enhancement factor, defined as number of particles above a threshold energy normalized to total number of particles, scales as $ ( q / m ) ^ { - \ alpha } $ where $ \ alpha $ increases with the energy threshold. we discuss our simulation results in the light of the sep observations. | arxiv:2307.13268 |
we show how two level atoms can be used to build microscopic models for mirrors and beamsplitters. the mirrors can have arbitrary shape allowing closed cavities to be built. it is possible to build networks or mirrors and beamsplitters and follow the time - evolution of the intensity of the radiation through the system. | arxiv:quant-ph/9902078 |
we determine conditions on q for the nonexistence of deep holes of the standard reed - solomon code of dimension k over f _ q generated by polynomials of degree k + d. our conditions rely on the existence of q - rational points with nonzero, pairwise - distinct coordinates of a certain family of hypersurfaces defined over f _ q. we show that the hypersurfaces under consideration are invariant under the action of the symmetric group of permutations of the coordinates. this allows us to obtain critical information concerning the singular locus of these hypersurfaces, from which the existence of q - rational points is established. | arxiv:1109.2265 |
in some galaxy clusters powerful agn have blown bubbles with cluster scale extent into the ambient medium. the main pressure support of these bubbles is not known to date, but cosmic rays are a viable possibility. for such a scenario copious gamma - ray emission is expected as a tracer of cosmic rays from these systems. hydra a, the closest galaxy cluster hosting a cluster scale agn outburst, located at a redshift of 0. 0538, is investigated for being a gamma - ray emitter with the high energy stereoscopic system ( h. e. s. s. ) array and the fermi large area telescope ( fermi - lat ). data obtained in 20. 2 hours of dedicated h. e. s. s. observations and 38 months of fermi - lat data, gathered by its usual all - sky scanning mode, have been analyzed to search for a gamma - ray signal. no signal has been found in either data set. upper limits on the gamma - ray flux are derived and are compared to models. these are the first limits on gamma - ray emission ever presented for galaxy clusters hosting cluster scale agn outbursts. the non - detection of hydra a in gamma - rays has important implications on the particle populations and physical conditions inside the bubbles in this system. for the case of bubbles mainly supported by hadronic cosmic rays, the most favorable scenario, that involves full mixing between cosmic rays and embedding medium, can be excluded. however, hadronic cosmic rays still remain a viable pressure support agent to sustain the bubbles against the thermal pressure of the ambient medium. the largest population of highly - energetic electrons which are relevant for inverse - compton gamma - ray production is found in the youngest inner lobes of hydra a. the limit on the inverse - compton gamma - ray flux excludes a magnetic field below half of the equipartition value of 16 mug in the inner lobes. | arxiv:1208.1370 |
the use of a relational time in quantum mechanics is a framework in which one promotes to quantum operators all variables in a system, and later chooses one of the variables to operate like a ` ` clock ' '. conditional probabilities are computed for variables of the system to take certain values when the ` ` clock ' ' specifies a certain time. this framework is attractive in contexts where the assumption of usual quantum mechanics of the existence of an external, perfectly classical clock, appears unnatural, as in quantum cosmology. until recently, there were problems with such constructions in ordinary quantum mechanics with additional difficulties in the context of constrained theories like general relativity. a scheme we recently introduced to consistently discretize general relativity removed such obstacles. since the clock is now an object subject to quantum fluctuations, the resulting evolution in the time is not exactly unitary and pure states decohere into mixed states. here we work out in detail the type of decoherence generated, and we find it to be of lindblad type. this is attractive since it implies that one can have loss of coherence without violating the conservation of energy. we apply the framework to a simple cosmological model to illustrate how a quantitative estimate of the effect could be computed. for most quantum systems it appears to be too small to be observed, although certain macroscopic quantum systems could in the future provide a testing ground for experimental observation. | arxiv:gr-qc/0402118 |
we calculate the inelastic scattering rates and the hot electron inelastic mean free paths for both monolayer and bilayer graphene on a polar substrate. we study the quasiparticle self - energy by taking into account both electron - electron and electron - surface optical ( so ) phonon interactions. in this calculation the leading order dynamic screening approximation ( g $ _ 0 $ w approximation ) is used to obtain the quasiparticle self - energy by treating electrons and phonons on an equal footing. we find that the strong coupling between the so phonon and plasmon leads to a new decay channel for the quasiparticle through the emission of the coupled mode, and gives rise to an abrupt increase in the scattering rate, which is absent in the uncoupled system. in monolayer graphene a single jump in the scattering rate occurs, arising from the emission of the low energy branch of the coupled plasmon - phonon modes. in bilayer graphene the emission of both low and high energy branches of the coupled modes contributes to the scattering rate and gives rise to two abrupt changes in the scattering rate. the jumps in the scattering rate can be potentially used in the hot electron device such as switching devices and oscillators. | arxiv:1409.8394 |
we show that two major carrier excitation mechanisms are present in ii - vi self - assembled quantum dots. the first one is related to direct excited state - ground state transition. it manifests itself by the presence of sharp and intense lines in the excitation spectrum measured from single quantum dots. apart from these lines, we also observe up to four much broader excitation lines. the energy spacing between these lines indicates that they are associated with absorption related to longitudinal optical phonons. by analyzing resonantly excited photoluminescence spectra, we are able to separate the contributions from these two mechanisms. in the case of cdte dots, the excited state - ground state relaxation is important for all dots in ensemble, while phonon - assisted processes are dominant for the dots with smaller lateral size. | arxiv:cond-mat/0310571 |
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