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we examine the stability of the valence bond solid ( vbs ) phase against the dzyaloshinskii - moriya ( dm ) interaction in the bipartite lattice. despite the vbs is vulnerable against the antiferromagnetic interaction, for example in the q - j model proposed by sandvik, where the quantum phase transition occurs at $ j ^ * / q = 0. 04 $, we found that on the contrary the vbs is very stable against the dm interaction. the quantum phase transition does not occur until d / q goes to infinity, where d is the strength of the dm interaction. the vbs in the alkt model and the haldane gap system also exhibit the same property. | arxiv:0907.0080 |
jord \ ' an and tanigawa recently introduced the $ d $ - dimensional algebraic connectivity $ a _ d ( g ) $ of a graph $ g $. this is a quantitative measure of the $ d $ - dimensional rigidity of $ g $ which generalizes the well - studied notion of spectral expansion of graphs. we present a new lower bound for $ a _ d ( g ) $ defined in terms of the spectral expansion of certain subgraphs of $ g $ associated with a partition of its vertices into $ d $ parts. in particular, we obtain a new sufficient condition for the rigidity of a graph $ g $. as a first application, we prove the existence of an infinite family of $ k $ - regular $ d $ - rigidity - expander graphs for every $ d \ ge 2 $ and $ k \ ge 2d + 1 $. conjecturally, no such family of $ 2d $ - regular graphs exists. second, we show that $ a _ d ( k _ n ) \ geq \ frac { 1 } { 2 } \ left \ lfloor \ frac { n } { d } \ right \ rfloor $, which we conjecture to be essentially tight. in addition, we study the extremal values $ a _ d ( g ) $ attained if $ g $ is a minimally $ d $ - rigid graph. | arxiv:2304.01306 |
space exemplifies the ultimate test - bed environment for any materials technology. the harsh conditions of space, with extreme temperature changes, lack of gravity and atmosphere, intense solar and cosmic radiation, and mechanical stresses of launch and deployment, represent a multifaceted set of challenges. the materials we engineer must not only meet these challenges, but they need to do so while keeping overall mass to a minimum and guaranteeing performance over long periods of time with no opportunity for repair. nanophotonic materials - - materials that embody structural variations on a scale comparable to the wavelength of light - - offer opportunities for addressing some of these difficulties. here, we examine how advances in nanophotonics and nanofabrication are enabling ultrathin and lightweight structures with unparalleled ability to shape light - matter interactions over a broad electromagnetic spectrum. from solar panels that can be fabricated in space to applications of light for propulsion, the next generation of lightweight and multifunctional photonic materials stands to both impact existing technologies and pave the way for new space technologies. | arxiv:2010.03524 |
quasi - local integrals of motion are a key concept underpinning the modern understanding of many - body localisation, an intriguing phenomenon in which interactions and disorder come together. despite the existence of several numerical ways to compute them - and astoundingly in the light of the observation that much of the phenomenology of many properties can be derived from them - it is not obvious how to directly measure aspects of them in real quantum simulations ; in fact, the smoking gun of their experimental observation is arguably still missing. in this work, we propose a way to extract the real - space properties of such quasi - local integrals of motion based on a spatially - resolved entanglement probe able to distinguish anderson from many - body localisation from non - equilibrium dynamics. we complement these findings with a new rigorous entanglement bound and compute the relevant quantities using tensor networks. we demonstrate that the entanglement gives rise to a well - defined length scale that can be measured in experiments. | arxiv:2301.01787 |
the msugra model predicts the polarization of the tau coming from the stau to bino decay in the co - annihilation region to be + 1. this can be exploited to extract this soft tau signal at lhc and also to measure the tiny mass differences between the stau and the bino lsp. moreover this strategy will be applicable for a wider class of bino lsp models, where the lighter stau has a right component at least of similar size as the left. | arxiv:0807.2390 |
we have combined measurements of the kinematics, morphology, and oxygen abundance of the ionized gas in \ izw18, one of the most metal - poor galaxies known, to examine the star formation history and chemical mixing processes. | arxiv:astro-ph/9601107 |
graphene - like materials can be effectively described by quantum electrodynamics in ( 2 + 1 ) - dimensions. in a pristine state, these systems exhibit a symmetry between the nonequivalent dirac points in the honeycomb lattice. realistic samples which include distortions and crystalline anisotropies are considered through mass gaps of topological and dynamical nature. in this work we show that the incorporation of an in - plane uniform external magnetic field on this pseudochiral asymmetric configuration generates a non - dissipative electric current aligned with the magnetic field : the pseudo chiral magnetic effect. this scenario resembles the chiral magnetic effect in quantum chromodynamics. | arxiv:1312.3274 |
ensembles of solid state defects in diamond make promising quantum sensors with high sensitivity and spatiotemporal resolution. the inhomogeneous broadening and drive amplitude variations across such ensembles have differing impacts on the sensitivity depending on the sensing scheme used, adding to the challenge of choosing the optimal sensing scheme for a particular sensing regime. in this work, we numerically investigate and compare the predicted sensitivity of schemes based on continuous - wave ( cw ) optically detected magnetic resonance ( odmr ) spectroscopy, pi - pulse odmr and ramsey interferometry for sensing using nitrogen - vacancy centers in the low - frequency ( < 10 khz ) range typical for signals from biological sources. we show that inhomogeneous broadening has the strongest impact on the sensitivity of ramsey interferometry, and drive amplitude variations least impact the sensitivity of cw odmr, with all methods constrained by the rabi frequency. based on our results, we can identify three different regions of interest. for inhomogeneous broadening less than 0. 3 mhz, typical of diamonds used in state of the art sensing experiments, ramsey interferometry yields the highest sensitivity. in the regime where inhomogeneous broadening is greater than 0. 3 mhz, such as for standard optical grade diamonds or in miniaturized integrated devices, drive amplitude variations determine the optimal protocol to use. for low to medium drive amplitude variations, the highest sensitivity is reached using pi - pulse odmr. for high drive amplitude variations, relevant for widefield microscopic imaging, cw odmr can yield the best sensing performance. | arxiv:2109.13028 |
a class of above - barrier quantum - scattering problems is shown to provide an experimentally - accessible platform for studying $ \ mathcal { pt } $ - symmetric schr \ " odinger equations that exhibit spontaneous $ \ mathcal { pt } $ symmetry breaking despite having purely real potentials. these potentials are one - dimensional, inverted, and unstable and have the form $ v ( x ) = - \ lvert x \ rvert ^ p $ ( $ p > 0 $ ), terminated at a finite length or energy to a constant value as $ x \ to \ pm \ infty $. the signature of unbroken $ \ mathcal { pt } $ symmetry is the existence of reflectionless propagating states at discrete real energies up to arbitrarily high energy. in the $ \ mathcal { pt } $ - broken phase, there are no such solutions. in addition, there exists an intermediate mixed phase, where reflectionless states exist at low energy but disappear at a fixed finite energy, independent of termination length. in the mixed phase exceptional points ( eps ) occur at specific $ p $ and energy values, with a quartic dip in the reflectivity in contrast to the quadratic behavior away from eps. $ \ mathcal { pt } $ - symmetry - breaking phenomena have not been previously predicted in a quantum system with a real potential and no reservoir coupling. the effects predicted here are measurable in standard cold - atom experiments with programmable optical traps. the physical origin of the symmetry - breaking transition is elucidated using a wkb force analysis that identifies the spatial location of the above - barrier scattering. | arxiv:2209.05426 |
early prediction of pediatric cardiac arrest ( ca ) is critical for timely intervention in high - risk intensive care settings. we introduce pedca - ft, a novel transformer - based framework that fuses tabular view of ehr with the derived textual view of ehr to fully unleash the interactions of high - dimensional risk factors and their dynamics. by employing dedicated transformer modules for each modality view, pedca - ft captures complex temporal and contextual patterns to produce robust ca risk estimates. evaluated on a curated pediatric cohort from the choa - cicu database, our approach outperforms ten other artificial intelligence models across five key performance metrics and identifies clinically meaningful risk factors. these findings underscore the potential of multimodal fusion techniques to enhance early ca detection and improve patient care. | arxiv:2502.07158 |
we describe the meson - meson data for the ( $ ij ^ { pc } = 00 ^ { + + } $ ) wave at $ 280 \ leq \ sqrt s \ leq 1900 $ mev in two approaches : ( i ) the k - matrix approach and ( ii ) the dispersion relation d - matrix method. with a good description of low energy data ( at $ 280 \ leq \ sqrt s \ leq 900 $ mev ) as well as the data of two - meson transition amplitudes and antiproton - proton annihilation into three pseudoscalar meson states ( at $ 450 \ leq \ sqrt s \ leq 1950 $ mev ) we have found the positions of the resonance poles : ( i ) for the $ \ sigma $ meson pole : $ m _ \ sigma = ( 390 \ pm 35 ) - i ( 235 \ pm 50 ) $ mev ; ( ii ) two poles for the $ f _ 0 ( 980 ) $, on the second sheet ( under the $ \ pi \ pi $ cut ) : $ m _ { i } = ( 1011 \ pm 5 ) - i ( 35 \ pm 5 ) $ mev, and on the third sheet ( under the $ \ pi \ pi $ and $ k \ bar k $ cuts ), $ m _ { ii } = ( 1035 \ pm 50 ) - i ( 460 \ pm 50 ) $ mev ; for the $ f _ 0 ( 1370 ) $ meson, $ m = ( 1285 \ pm 30 ) - i ( 160 \ pm 20 ) $ mev ; for the $ f _ 0 ( 1500 ) $ meson, $ m = ( 1488 \ pm 4 ) - i ( 53 \ pm 5 ) $ mev ; for the $ f _ 0 ( 1790 ) $ meson, $ m = ( 1775 \ pm 25 ) - i ( 140 \ pm 15 ) $ mev and for the broad state $ f _ 0 ( 1200 - 1600 ) $ $ m = ( 1540 \ pm 120 ) - i ( 550 \ pm 70 ) $ mev. our estimation of the scalar - isoscalar scattering length obtained under different parameterizations and assumptions about the quality of low energy $ \ pi \ pi $ scattering data is $ a ^ 0 _ 0 = ( 0. 215 \ pm 0. 040 ) \ mu ^ { - 1 } _ \ pi $. we also discuss the idea | arxiv:1105.5923 |
extra - dimensional theories contain additional degrees of freedom related to the geometry of the extra space which can be interpreted as new particles. such theories allow to reformulate most of the fundamental problems of physics from a completely different point of view. in this essay we concentrate on the brane fluctuations which are present in brane - worlds, and how such oscillations of the own space - time geometry along curved extra dimensions can help to resolve the universe missing mass problem. the energy scales involved in these models are low compared to the planck scale, and this means that some of the brane fluctuations distinctive signals could be detected in future colliders and in direct or indirect dark matter searches. | arxiv:hep-ph/0405165 |
there is a large variety of machine learning methodologies that are based on the extraction of spectral geometric information from data. however, the implementations of many of these methods often depend on traditional eigensolvers, which present limitations when applied in practical online big data scenarios. to address some of these challenges, researchers have proposed different strategies for training neural networks as alternatives to traditional eigensolvers, with one such approach known as spectral neural network ( snn ). in this paper, we investigate key theoretical aspects of snn. first, we present quantitative insights into the tradeoff between the number of neurons and the amount of spectral geometric information a neural network learns. second, we initiate a theoretical exploration of the optimization landscape of snn ' s objective to shed light on the training dynamics of snn. unlike typical studies of convergence to global solutions of nn training dynamics, snn presents an additional complexity due to its non - convex ambient loss function. | arxiv:2310.00729 |
searches for neutral higgs bosons produced at lep in association with z bosons, in pairs and in the yukawa process are presented in this paper. higgs boson decays into b quarks, tau leptons, or other higgs bosons are considered, giving rise to four - b, four - b + jets, six - b and four - tau final states, as well as mixed modes with b quarks and tau leptons. the whole mass domain kinematically accessible at lep in these topologies is searched. the analysed data set covers both the lep1 and lep2 energy ranges and exploits most of the luminosity recorded by the delphi experiment. no convincing evidence for a signal is found, and results are presented in the form of mass - dependent upper bounds on coupling factors ( in units of model - independent reference cross - sections ) for all processes, allowing interpretation of the data in a large class of models. | arxiv:hep-ex/0410017 |
image - based virtual try - on aims to transfer target in - shop clothing to a dressed model image, the objectives of which are totally taking off original clothing while preserving the contents outside of the try - on area, naturally wearing target clothing and correctly inpainting the gap between target clothing and original clothing. tremendous efforts have been made to facilitate this popular research area, but cannot keep the type of target clothing with the try - on area affected by original clothing. in this paper, we focus on the unpaired virtual try - on situation where target clothing and original clothing on the model are different, i. e., the practical scenario. to break the correlation between the try - on area and the original clothing and make the model learn the correct information to inpaint, we propose an adaptive mask training paradigm that dynamically adjusts training masks. it not only improves the alignment and fit of clothing but also significantly enhances the fidelity of virtual try - on experience. furthermore, we for the first time propose two metrics for unpaired try - on evaluation, the semantic - densepose - ratio ( sdr ) and skeleton - lpips ( s - lpips ), to evaluate the correctness of clothing type and the accuracy of clothing texture. for unpaired try - on validation, we construct a comprehensive cross - try - on benchmark ( cross - 27 ) with distinctive clothing items and model physiques, covering a broad try - on scenarios. experiments demonstrate the effectiveness of the proposed methods, contributing to the advancement of virtual try - on technology and offering new insights and tools for future research in the field. the code, model and benchmark will be publicly released. | arxiv:2403.08453 |
we prove a folklore result which gives a sequence of necessary and sufficient conditions for a stably symplectic manifold to define a nilpotent element in the symplectic bordism ring. | arxiv:1410.3847 |
image - to - image translation is to learn a mapping between images from a source domain and images from a target domain. in this paper, we introduce the attention mechanism directly to the generative adversarial network ( gan ) architecture and propose a novel spatial attention gan model ( spa - gan ) for image - to - image translation tasks. spa - gan computes the attention in its discriminator and use it to help the generator focus more on the most discriminative regions between the source and target domains, leading to more realistic output images. we also find it helpful to introduce an additional feature map loss in spa - gan training to preserve domain specific features during translation. compared with existing attention - guided gan models, spa - gan is a lightweight model that does not need additional attention networks or supervision. qualitative and quantitative comparison against state - of - the - art methods on benchmark datasets demonstrates the superior performance of spa - gan. | arxiv:1908.06616 |
collinear factorized perturbative quantum chromodynamics ( pqcd ) model predictions are compared for $ p + { \ rm pb } $ at 5. 02 $ a $ tev to test nuclear shadowing of parton distribution at the large hadron collider ( lhc ). the pseudorapidity distribution the nuclear modification factor ( nmf ), $ r _ { p { \ rm pb } } ( y = 0, p _ t < 20 \ ; { \ rm gev } / { \ it c } ) = dn _ { p { \ rm pb } } / ( n _ { \ rm coll } ( b ) dn _ { pp } ) $ and the pseudorapidity asymmetry $ y _ { asym } ^ { h } ( p _ t ) = r ^ h _ { ppb } ( p _ t, \ eta < 0 ) / r ^ h _ { ppb } ( p _ t, \ eta > 0 ) $ are computed using { \ small hijing / b \ = b v2. 0 model } and a pqcd improved parton model ktpqcd \ _ v2. 0 which embedded generalized parton distribution functions ( pdfs ). these results are updated calculations of those presented in phys. rev. c { \ bf 85 }, 024903 ( 2012 ). | arxiv:1211.2256 |
we study a reaction diffusion system of the activator - inhibitor type with inhomogeneous reaction terms showing spatiotemporal chaos. we analyze the topological properties of the unstable periodic orbits in the slow chaotic dynamics appearing, which can be embedded in three dimensions. we perform a bi - orthogonal decomposition analyzing the minimum number of modes necessary to find the same organization of unstable orbits. | arxiv:cond-mat/0410574 |
in this paper, we present an empirical verification of the method of determining the doppler spectrum ( ds ) from the power angular spectrum ( pas ). measurements were made for the frequency of 3. 5 ghz, under non - line - of - sight conditions in suburban areas characteristic of a university campus. in the static scenario, the measured pas was the basis for the determination of dss, which were compared with the dss measured in the mobile scenario. the obtained results show that the proposed method gives some approximation to ds determined with the classic methods used so far. | arxiv:2503.12443 |
the emergence of cloud computing has made dynamic provisioning of elastic capacity to applications on - demand. cloud data centers contain thousands of physical servers hosting orders of magnitude more virtual machines that can be allocated on demand to users in a pay - as - you - go model. however, not all systems are able to scale up by just adding more virtual machines. therefore, it is essential, even for scalable systems, to project workloads in advance rather than using a purely reactive approach. given the scale of modern cloud infrastructures generating real time monitoring information, along with all the information generated by operating systems and applications, this data poses the issues of volume, velocity, and variety that are addressed by big data approaches. in this paper, we investigate how utilization of big data analytics helps in enhancing the operation of cloud computing environments. we discuss diverse applications of big data analytics in clouds, open issues for enhancing cloud operations via big data analytics, and architecture for anomaly detection and prevention in clouds along with future research directions. | arxiv:1510.06486 |
very recently, a new graphene - like crystalline, hole - free, 2d - single - layer carbon nitride c3n, has been fabricated by polymerization of 2, 3 - diaminophenazine and used to fabricate a field - effect transistor device with an on - off current ratio reaching ( adv. mater. 2017, 1605625 ). heat dissipation plays a vital role in its practical applications, and therefore the thermal transport properties need to be explored urgently. in this paper, we perform first - principles calculations combined with phonon boltzmann transport equation to investigate the phononic thermal transport properties of monolayer c3n, and meanwhile, a comparison with graphene is given. our calculated intrinsic lattice thermal conductivity of c3n is 380 w / mk at room temperature, which is one order of magnitude lower than that of graphene ( 3550 w / mk at 300 k ), but is greatly higher than many other typical 2d materials. the underlying mechanisms governing the thermal transport were thoroughly discussed and compared to graphene, including group velocities, phonon relax time, the contribution from phonon branches, phonon anharmonicity and size effect. the fundamental physics understood from this study may shed light on further studies of the newly fabricated 2d crystalline c3n sheets. | arxiv:1709.08821 |
the inverse faraday effect induced in magnetic films by ultrashort laser pulses allows excitation and control of spins at ghz and sub - thz frequencies. frequency of the excited magnetization precession is easily tunable by the external magnetic field. on the other hand, phase of the precession hardly depends on magnetic field. here we demonstrate an approach for the control of the precession phase by variation of the incidence angle of the laser pulses. in particular, theoretical consideration states that the phase increases with increase of the incidence angle and for small angles this relation is a direct proportionality. experimental studies confirm this conclusion and provide shift of phase by about 4 deg. for the declination of the incidence angle by 15 deg. from the normal. this study provides a simple way for additional manipulation with optically excited magnetization dynamics, which is of importance for different spintronic applications. | arxiv:1805.05936 |
we present a new polar representation of quaternions inspired by the cayley - dickson representation. in this new polar representation, a quaternion is represented by a pair of complex numbers as in the cayley - dickson form, but here these two complex numbers are a complex ' modulus ' and a complex ' argument '. as in the cayley - dickson form, the two complex numbers are in the same complex plane ( using the same complex root of - 1 ), but the complex phase is multiplied by a different complex root of - 1 in the exponential function. we show how to calculate the amplitude and phase from an arbitrary quaternion in cartesian form. | arxiv:0802.0852 |
motivated from the quadratic dependence of peak structural displacements to the pulse period, $ t _ p $, of pulse - like ground motions, this paper revisits the $ t _ p $ - - $ m _ \ text { w } $ relations of ground motions generated from near - source earthquakes with epicentral distances, $ d \ leq $ 20 km. a total of 1260 ground motions are interrogated with wavelet analysis to identify energetic acceleration pulses ( not velocity pulses ) and extract their optimal period, $ t _ p $, amplitude, $ a _ p $, phase, $ \ phi $ and number of half - cycles, $ \ gamma $. the interrogation of acceleration records with wavelet analysis is capable of extracting shorter - duration distinguishable pulses with engineering significance, which override the longer near - source pulses. our wavelet analysis identified 109 pulse - like records from normal faults, 188 records from reverse faults and 125 records from strike - slip faults, all with epicentral distances $ d \ leq $ 20 km. regression analysis on the extracted data concluded that the same $ t _ p $ - - $ m _ \ text { w } $ relation can be used for pulse - like ground motions generated either from strike - slip faults or from normal faults ; whereas, a different $ t _ p $ - - $ m _ { \ text { w } } $ relation is proposed for reverse faults. the study concludes that for the same moment magnitude, $ m _ { \ text { w } } $, the pulse periods of ground motions generated from strike - slip faults are on average larger than these from reverse faults. most importantly, our wavelet analysis on acceleration records produces $ t _ p $ - - $ m _ { \ text { w } } $ relations with a lower slope than the slopes of the $ t _ p $ - - $ m _ { \ text { w } } $ relations presented by past investigators after merely fitting velocity pulses. as a result, our proposed $ t _ p $ - - $ m _ { \ text { w } } $ relations yield lower $ t _ p $ values for larger - magnitude earthquakes ( say $ m _ { \ text { w } } > $ 6 ), allowing for the estimation of dependable peak structural displacements that scale invariably with $ a _ pt _ p ^ { \ text { 2 } } $. | arxiv:2104.11102 |
prompt engineering is a new paradigm for enhancing the performance of trained neural network models. for optimizing text - style prompts, existing methods usually individually operate small portions of a text step by step, which either breaks the fluency or could not globally adjust a prompt. since large language models ( llms ) have powerful ability of generating coherent texts token by token, can we utilize llms for improving prompts? based on this motivation, in this paper, considering a trained llm as a text generator, we attempt to design a black - box evolution algorithm for automatically optimizing texts, namely spell ( semantic prompt evolution based on a llm ). the proposed method is evaluated with different llms and evolution parameters in different text tasks. experimental results show that spell could rapidly improve the prompts indeed. we further explore the evolution process and discuss on the limitations, potential possibilities and future work. | arxiv:2310.01260 |
although tremendous strides have been made in uncontrolled face detection, efficient face detection with a low computation cost as well as high precision remains an open challenge. in this paper, we point out that training data sampling and computation distribution strategies are the keys to efficient and accurate face detection. motivated by these observations, we introduce two simple but effective methods ( 1 ) sample redistribution ( sr ), which augments training samples for the most needed stages, based on the statistics of benchmark datasets ; and ( 2 ) computation redistribution ( cr ), which reallocates the computation between the backbone, neck and head of the model, based on a meticulously defined search methodology. extensive experiments conducted on wider face demonstrate the state - of - the - art efficiency - accuracy trade - off for the proposed \ scrfd family across a wide range of compute regimes. in particular, \ scrfdf { 34 } outperforms the best competitor, tinaface, by $ 3. 86 \ % $ ( ap at hard set ) while being more than \ emph { 3 $ \ times $ faster } on gpus with vga - resolution images. we also release our code to facilitate future research. | arxiv:2105.04714 |
in this paper, we first study a new extremal problem recently posed by conlon and tyomkyn ~ ( arxiv : 2002. 00921 ). given a graph $ h $ and an integer $ k \ geqslant 2 $, let $ f _ { k } ( n, h ) $ be the smallest number of colors $ c $ such that there exists a proper edge - coloring of the complete graph $ k _ { n } $ with $ c $ colors containing no $ k $ vertex - disjoint color - isomorphic copies of $ h $. using algebraic properties of polynomials over finite fields, we give an explicit proper edge - coloring of $ k _ { n } $ and show that $ f _ { k } ( n, c _ { 4 } ) = \ theta ( n ) $ when $ k \ geqslant 3 $ and $ n \ rightarrow \ infty $. the methods we used in the edge - coloring may be of some independent interest. we also consider a related generalized ramsey problem. for given graphs $ g $ and $ h, $ let $ r ( g, h, q ) $ be the minimum number of edge - colors ( not necessarily proper ) of $ g $, such that the edges of every copy of $ h \ subseteq g $ together receive at least $ q $ distinct colors. establishing the relation to the tur \ ' { a } n number of specified bipartite graphs, we obtain some general lower bounds for $ r ( k _ { n, n }, k _ { s, t }, q ) $ with a broad range of $ q $. | arxiv:2004.01932 |
the intrinsic mobility degradation coefficient, contact resistance and the transconductance parameter of graphene field - effect transistors ( gfets ) are extracted for different technologies by considering a novel transport model embracing mobility degradation effects within the charge channel control description. by considering the mobility degradation - based model, a straightforward extraction methodology, not provided before, is enabled by applying the concept of the well - known y - function to the \ textit { i - v } device characteristics. the method works regardless the gate device architecture. an accurate description of experimental data of fabricated devices is achieved with the underlying transport equation by using the extracted parameters. an evaluation of the channel resistance, enabled by the extracted parameters here, has been also provided. | arxiv:2206.00644 |
we investigate the rate of false planetary transit detection due to blending with eclipsing binaries. our approach is purely empirical and is based on the analysis of the artificially blended light curves of the eclipsing binary stars in the large magellanic cloud from the archive of the optical gravitational lensing experiment ( ogle ). employing parameters that characterize the significance of the transit and the amplitude of the variation out of the transit, we can substantially limit the number of potential false positives. further constraint comes from the expected length of the transit by a possible planetary companion. by the application of these criteria we are left only with 18 candidates from the full sample of 2495 stars. visual inspection of these remaining variables eliminates all of them for obvious reasons ( e. g., for visible fingerprints of orbital eccentricity ). we draw the attention to the short - period stars, where the false alarm rate is especially low. | arxiv:astro-ph/0508081 |
by providing homogeneous photometric and spectroscopic data of high quality for very large and objectively selected samples of galaxies, the sloan digital sky survey allows statistical studies of the physical properties of galaxies and agn to be carried out at an unprecedented level of precision and detail. here we publicly release catalogues of derived physical properties for 211, 894 galaxies, including 33, 589 narrow - line agn. these are complete samples with well understood selection criteria drawn from the normal galaxy spectroscopic sample in the second sdss public data release ( dr2 ). we list properties obtained from the sdss spectroscopy and photometry using modelling techniques presented in papers already published by our group. these properties include : stellar masses ; stellar mass - to - light ratios ; attenuation of the starlight by dust ; indicators of recent major starbursts ; current total and specific star - formation rates, both for the regions with spectroscopy and for the galaxies as a whole ; gas - phase metallicities ; agn classifications based on the standard emission line ratio diagnostic diagrams and agn [ oiii ] emission line luminosities. we also list our own measurements of absorption line indices and emission line fluxes from which these quantities were derived, together with a few quantities from the standard sdss pipelines which play an important role in our work. many other observed properties of these galaxies can be obtained from the sdss dr2 catalogues themselves. we will add further physical properties to this release site as the relevant papers are accepted for publication. catalogies containing these parameters may be accessed at http : / / www. mpa - garching. mpg. de / sdss /. | arxiv:astro-ph/0406220 |
in this paper, we propose an attentional generative adversarial network ( attngan ) that allows attention - driven, multi - stage refinement for fine - grained text - to - image generation. with a novel attentional generative network, the attngan can synthesize fine - grained details at different subregions of the image by paying attentions to the relevant words in the natural language description. in addition, a deep attentional multimodal similarity model is proposed to compute a fine - grained image - text matching loss for training the generator. the proposed attngan significantly outperforms the previous state of the art, boosting the best reported inception score by 14. 14 % on the cub dataset and 170. 25 % on the more challenging coco dataset. a detailed analysis is also performed by visualizing the attention layers of the attngan. it for the first time shows that the layered attentional gan is able to automatically select the condition at the word level for generating different parts of the image. | arxiv:1711.10485 |
we study the information transfer model for biological evolution with several kinds of fitness function. the system is stimulated to volve into a stationary state, depending on the fitness function and on the dimension of the lattice formed by the species. in particular the system yields time series of the mutation rate which exhibits the $ 1 / f $ spectrum, thus explains the power - law behavior in fossil data. effects of shortcuts introduced on the lattice are also examined and the evolution activity is usually found to increase in a well - growing system although the reduction of the overall activity may also be observed in the presence of shortcuts, depending on the initial configuration. | arxiv:cond-mat/0504092 |
scalability and accuracy are well recognized challenges in deep extreme multi - label learning where the objective is to train architectures for automatically annotating a data point with the most relevant subset of labels from an extremely large label set. this paper develops the deepxml framework that addresses these challenges by decomposing the deep extreme multi - label task into four simpler sub - tasks each of which can be trained accurately and efficiently. choosing different components for the four sub - tasks allows deepxml to generate a family of algorithms with varying trade - offs between accuracy and scalability. in particular, deepxml yields the astec algorithm that could be 2 - 12 % more accurate and 5 - 30x faster to train than leading deep extreme classifiers on publically available short text datasets. astec could also efficiently train on bing short text datasets containing up to 62 million labels while making predictions for billions of users and data points per day on commodity hardware. this allowed astec to be deployed on the bing search engine for a number of short text applications ranging from matching user queries to advertiser bid phrases to showing personalized ads where it yielded significant gains in click - through - rates, coverage, revenue and other online metrics over state - of - the - art techniques currently in production. deepxml ' s code is available at https : / / github. com / extreme - classification / deepxml | arxiv:2111.06685 |
in this paper we study motivic amplitudes - - objects which contain all of the essential mathematical content of scattering amplitudes in planar sym theory in a completely canonical way, free from the ambiguities inherent in any attempt to choose particular functional representatives. we find that the cluster structure on the kinematic configuration space conf _ n ( p ^ 3 ) underlies the structure of motivic amplitudes. specifically, we compute explicitly the coproduct of the two - loop seven - particle mhv motivic amplitude a _ { 7, 2 } and find that like the previously known six - particle amplitude, it depends only on certain preferred coordinates known in the mathematics literature as cluster x - coordinates on conf _ n ( p ^ 3 ). we also find intriguing relations between motivic amplitudes and the geometry of generalized associahedrons, to which cluster coordinates have a natural combinatoric connection. for example, the obstruction to a _ { 7, 2 } being expressible in terms of classical polylogarithms is most naturally represented by certain quadrilateral faces of the appropriate associahedron. we also find and prove the first known functional equation for the trilogarithm in which all 40 arguments are cluster x - coordinates of a single algebra. in this respect it is similar to abel ' s 5 - term dilogarithm identity. | arxiv:1305.1617 |
standard stochastic control methods assume that the probability distribution of uncertain variables is available. unfortunately, in practice, obtaining accurate distribution information is a challenging task. to resolve this issue, we investigate the problem of designing a control policy that is robust against errors in the empirical distribution obtained from data. this problem can be formulated as a two - player zero - sum dynamic game problem, where the action space of the adversarial player is a wasserstein ball centered at the empirical distribution. we propose computationally tractable value and policy iteration algorithms with explicit estimates of the number of iterations required for constructing an $ \ epsilon $ - optimal policy. we show that the contraction property of associated bellman operators extends a single - stage out - of - sample performance guarantee, obtained using a measure concentration inequality, to the corresponding multi - stage guarantee without any degradation in the confidence level. in addition, we characterize an explicit form of the optimal distributionally robust control policy and the worst - case distribution policy for linear - quadratic problems with wasserstein penalty. our study indicates that dynamic programming and kantorovich duality play a critical role in solving and analyzing the wasserstein distributionally robust stochastic control problems. | arxiv:1812.09808 |
in this paper, we explore a new, yet critical, side - channel attack against intel software guard extension ( sgx ), called a branch shadowing attack, which can reveal fine - grained control flows ( i. e., each branch ) of an enclave program running on real sgx hardware. the root cause of this attack is that intel sgx does not clear the branch history when switching from enclave mode to non - enclave mode, leaving the fine - grained traces to the outside world through a branch - prediction side channel. however, exploiting the channel is not so straightforward in practice because 1 ) measuring branch prediction / misprediction penalties based on timing is too inaccurate to distinguish fine - grained control - flow changes and 2 ) it requires sophisticated control over the enclave execution to force its execution to the interesting code blocks. to overcome these challenges, we developed two novel exploitation techniques : 1 ) intel pt - and lbr - based history - inferring techniques and 2 ) apic - based technique to control the execution of enclave programs in a fine - grained manner. as a result, we could demonstrate our attack by breaking recent security constructs, including oram schemes, sanctum, sgx - shield, and t - sgx. not limiting our work to the attack itself, we thoroughly studied the feasibility of hardware - based solutions ( e. g., branch history clearing ) and also proposed a software - based countermeasure, called zigzagger, to mitigate the branch shadowing attack in practice. | arxiv:1611.06952 |
in recent years, studies on cyclic molecular nanomagnets have captivated the attention of researchers. these magnets are finite in size and contain very large spins. they are interesting because they possess macroscopic quantum tunneling of n \ ' eel vectors. for antiferromagnetic molecular nanomagnets with finite number of even - numbered coupled spins, tunneling involves two classical localized n \ ' eel ground states separated by a magnetic energy barrier. the question is : can such phenomena be observed in nano magnets with odd number of magnetic ions? the answer is not directly obvious because cyclic chains with odd - numbered coupled spins are frustrated as one cannot obtain a perfect n \ ' eel order. these frustrated spins can indeed be observed experimentally, so they are of interest. in this letter, we theoretically investigate macroscopic quantum tunneling in these odd spin systems with arbitrary spins $ s $, in the presence of a magnetic field applied along the plane of the magnet. in contrast to systems with an even - numbered coupled spins, the ground state of the cyclic odd - spin system contains a topological soliton due to spin frustration. thus the classical ground state is $ 2n $ - fold degenerate as the soliton can be placed anywhere along the ring with total $ s _ z = \ pm s $. small quantum fluctuations delocalize the soliton with a formation of an energy band. we obtain this energy band using degenerate perturbation theory at order $ 2s $. we show that the soliton ground state is chiral for half - odd integer spins and non - chiral for integer spins. from the structure of the energy band we infer that as the value of the spin increases the inelastic polarized neutron - scattering intensity may increase or decrease depending on the strengths of the parameters of the hamiltonian. | arxiv:1502.05684 |
) $, not multiples of each other, such that $ ( ak, bl ) $ is a pythagorean pair ; the analogous result holds for quadratic pythapotent pairs. | arxiv:2101.08163 |
we show that the group of presentation $ < a, b, c, s, t \ mid c = ab = ba, \, c ^ 2 = sas ^ { - 1 } = tbt ^ { - 1 } > $ ( introduced by d. wise ) has the property of rapid decay. | arxiv:1211.2428 |
semantic communications have emerged as a crucial research direction for future wireless communication networks. however, as wireless systems become increasingly complex, the demands for computation and communication resources in semantic communications continue to grow rapidly. this paper investigates the trade - off between computation and communication in wireless semantic communications, taking into consideration transmission task delay and performance constraints within the semantic communication framework. we propose a novel tradeoff metric to analyze the balance between computation and communication in semantic transmissions and employ the deep reinforcement learning ( drl ) algorithm to minimize this metric, thereby reducing the cost associated with balancing computation and communication. through simulations, we analyze the tradeoff between computation and communication and demonstrate the effectiveness of optimizing this trade - off metric. | arxiv:2504.10357 |
1109 / mc. 2008. 541. issn 0018 - 9162. hamilton, m. h. ( september 2018 ). " what the errors tell us ". ieee software. 35 ( 5 ) : 32 – 37. doi : 10. 1109 / ms. 2018. 290110447. s2cid 52896962. = = personal life = = hamilton has a sister, kathryn heafield. she met her first husband, james cox hamilton, in the mid - 1950s while attending college. they were married on june 15, 1958, the summer after she graduated from earlham. she briefly taught high school mathematics and french at a public school in boston, indiana. the couple then moved to boston, massachusetts, where they had a daughter, lauren, born on november 10, 1959. they divorced in 1967 and margaret married dan lickly two years later. = = see also = = list of pioneers in computer science = = references = = = = further reading = = steafel, eleanor ( july 20, 2019 ). " one woman in a room full of men ". the telegraph magazine. london : daily telegraph plc. pp. 56 – 59, 61. oclc 69022829. = = external links = = hamilton technologies, inc. mit news margaret hamilton archived september 5, 2017, at the wayback machine video produced by makers : women who make america margaret hamilton ’ 58 – presidential medal of freedom recipient archived july 30, 2019, at the wayback machine : earlham college profile | https://en.wikipedia.org/wiki/Margaret_Hamilton_(software_engineer) |
in this study we present a metric of consensus for likert scales. the measure gives the level of agreement as the percentage of consensus among respondents. the proposed framework allows to design a positional indicator that gives the degree of agreement for each item independently of the number of reply options. in order to assess the performance of the proposed metric of consensus, in an iterated one - period ahead forecasting experiment we test whether the inclusion of the degree of agreement in expectations regarding the evolution of unemployment improves out - of - sample forecast accuracy in eight european countries. we find evidence that the degree of agreement among consumers contains useful information to predict unemployment rates. these results show the usefulness of consensus - based metrics to track the evolution of economic variables. | arxiv:1809.10493 |
in this paper, we study the size of the level sets of all lyapunov exponents. for typical cocycles, we establish a variational relation between the topological entropy of the level sets of lyapunov exponents and the topological pressure of the generalized singular value function. | arxiv:2210.11574 |
we study macroscopic electrical or thermal conductivity of a composite made of straight or coiled nanowires suspended in poorly conducting medium. we assume that volume fraction of the wires is so large that spaces occupied by them overlap, but there is still enough room to distribute wires isotropically. we found a wealth of scaling regimes at different ratios of conductivities of the wire, $ \ sigma _ 1 $ and of the medium, $ \ sigma _ 2 $, length of wires, their persistent length and volume fraction. there are large ranges of parameters where macroscopic conductivity is proportional to $ ( \ sigma _ { 1 } \ sigma _ { 2 } ) ^ { 1 / 2 } $. these results are directly applicable to the calculation of the macroscopic diffusion constant of the nonspecific dna - binding proteins in semidilute dna solution. | arxiv:cond-mat/0602154 |
we use holographic duality to analyze the drag force on, and consequent energy loss of, a heavy quark moving through a strongly coupled conformal fluid with non - vanishing gradients in its velocity and temperature. we derive the general expression for the drag force to first order in the fluid gradients. using this general expression, we show that a quark that is instantaneously at rest, relative to the fluid, in a fluid whose velocity is changing with time feels a nonzero force. and, we show that for a quark that is moving ultra - relativistically, the first order gradient " corrections " become larger than the zeroth order drag force, suggesting that the gradient expansion may be unreliable in this regime. we illustrate the importance of the fluid gradients for heavy quark energy loss by considering a fluid with one - dimensional boost invariant bjorken expansion as well as the strongly coupled plasma created by colliding sheets of energy. | arxiv:1311.5577 |
spatially coupled ( sc ) interleaving is proposed to improve the performance of iterative multiuser detection and decoding ( mudd ) for quasi - static fading multiple - input multiple - output systems. the linear minimum mean - squared error ( lmmse ) demodulator is used to reduce the complexity and to avoid error propagation. furthermore, sliding window mudd is proposed to circumvent an increase of the decoding latency due to sc interleaving. theoretical and numerical analyses show that sc interleaving can improve the performance of the iterative lmmse mudd for regular low - density parity - check codes. | arxiv:1308.3957 |
the use of large language models ( llms ) such as openai ' s gpt - 4 in technical customer support ( tcs ) has the potential to revolutionize this area. this study examines automated text correction, summarization of customer inquiries and question answering using llms. through prototypes and data analyses, the potential and challenges of integrating llms into the tcs will be demonstrated. our results show promising approaches for improving the efficiency and quality of customer service through llms, but also emphasize the need for quality - assured implementation and organizational adjustments in the data ecosystem. | arxiv:2406.01407 |
inverse problems arise anywhere we have indirect measurement. as, in general they are ill - posed, to obtain satisfactory solutions for them needs prior knowledge. classically, different regularization methods and bayesian inference based methods have been proposed. as these methods need a great number of forward and backward computations, they become costly in computation, in particular, when the forward or generative models are complex and the evaluation of the likelihood becomes very costly. using deep neural network surrogate models and approximate computation can become very helpful. however, accounting for the uncertainties, we need first understand the bayesian deep learning and then, we can see how we can use them for inverse problems. in this work, we focus on nn, dl and more specifically the bayesian dl particularly adapted for inverse problems. we first give details of bayesian dl approximate computations with exponential families, then we will see how we can use them for inverse problems. we consider two cases : first the case where the forward operator is known and used as physics constraint, the second more general data driven dl methods. keyword : neural network, variational bayesian inference, bayesian deep learning ( dl ), inverse problems, physics based dl. | arxiv:2308.15492 |
the developments in the experimental facilities and analyses techniques have recently lead to the observation of many hadronic states ranging from excitations of conventional hadrons to various exotic states. the baryons with single heavy quark are among these states providing an attractive field of research to get a better understanding of the nonperturbative nature of the strong interaction. recently, the belle collaboration announced observation of the state $ \ lambda _ c ( 2910 ) ^ + $ with a mass $ 2913. 8 \ pm5. 6 \ pm3. 8 ~ \ mathrm { mev } / c ^ 2 $ and width $ 51. 8 \ pm20. 0 \ pm18. 8 ~ \ mathrm { mev } $. in the present study, by the mass analyses of different excitations at $ \ lambda _ c $ channel and their comparison with existing experimental information, we find that the spin - parity of this newly found excited state is $ j ^ p = \ frac { 1 } { 2 } ^ - $ and it is a $ 2p $ state denoting by $ \ lambda _ c ( \ frac { 1 } { 2 } ^ -, 2p ) $. we predict its current coupling as well, which can be served as one of the main input parameters to investigate different decays and interactions of this particle. we also determine the mass and current coupling of $ \ lambda _ b ( \ frac { 1 } { 2 } ^ -, 2p ) $ as possible bottom counterpart of the new $ \ lambda _ c ( 2910 ) ^ + $ state, which may be in agenda of different experiments in near future. | arxiv:2207.03022 |
speech emotion recognition ( ser ) is a vital component in various everyday applications. cross - corpus ser models are increasingly recognized for their ability to generalize performance. however, concerns arise regarding fairness across demographics in diverse corpora. existing fairness research often focuses solely on corpus - specific fairness, neglecting its generalizability in cross - corpus scenarios. our study focuses on this underexplored area, examining the gender fairness generalizability in cross - corpus ser scenarios. we emphasize that the performance of cross - corpus ser models and their fairness are two distinct considerations. moreover, we propose the approach of a combined fairness adaptation mechanism to enhance gender fairness in the ser transfer learning tasks by addressing both source and target genders. our findings bring one of the first insights into the generalizability of gender fairness in cross - corpus ser systems. | arxiv:2501.00995 |
measurements of air showers are accumulating at an increasing rate while construction proceeds at the pierre auger observatory. although the southern site is only half complete, the cumulative exposure is already similar to those achieved by the largest forerunner experiments. a measurement of the cosmic ray energy spectrum in the southern sky is reported here. the methods are simple and robust, exploiting the combination of fluorescence detector ( fd ) and surface detector ( sd ). the methods do not rely on detailed numerical simulation or any assumption about the chemical composition. | arxiv:astro-ph/0507150 |
quantum signal processing ( qsp ) and quantum singular value transformation ( qsvt ) are powerful techniques for the development of quantum procedures. they allow to derive circuits preparing desired polynomial transformations. recent research [ alexis et al. 2024 ] showed that non - linear fourier analysis ( nlfa ) can be employed to numerically compute a qsp protocol, with provable stability. in this work we extend their result, showing that gqsp and the non - linear fourier transform over $ su ( 2 ) $ are the same object. this statement - proven by a simple argument - has a bunch of consequences : first, the riemann - hilbert - weiss algorithm can be turned, with little modifications and no penalty in complexity, into a unified, provably stable algorithm for the computation of phase factors in any qsp variant, including gqsp. secondly, we derive a uniqueness result for the existence of gqsp phase factors based on the bijectivity of the non - linear fourier transform. furthermore, nlfa provides a complete theory of infinite generalized quantum signal processing, which characterizes the class of functions approximable by gqsp protocols. | arxiv:2503.03026 |
bose - einstein condensation ( bec ) of composite diquarks in quark matter ( the color superconductor phase ) is discussed using the quasi - chemical equilibrium theory at a relatively low density region near the deconfinement phase transition, where dynamical quark - pair fluctuations are assumed to be described as bosonic degrees of freedom ( diquarks ). a general formulation is given for the diquark formation and particle - antiparticle pair - creation processes in the relativistic flamework, and some interesting properties are shown, which are characteristic for the relativistic many - body system. behaviors of transition temperature and phase diagram of the quark - diquark matter are generally presented in model parameter space, and their asymptotic behaviors are also discussed. as an application to the color superconductivity, the transition temperatures and the quark and diquark density profiles are calculated in case with constituent / current quarks, where the diquark is in bound / resonant state. we obtained $ t _ c \ sim 60 - 80 $ mev for constituent quarks and $ t _ c \ sim 130 $ mev for current quarks at a moderate density ( $ \ rho _ b \ sim 3 \ rho _ 0 $ ). the method is also developed to include interdiquark interactions into the quasi - chemical equilibrium theory within a mean - field approximation, and it is found that a possible repulsive diquark - diquark interaction lowers the transition temperature by nearly 50 %. | arxiv:hep-ph/0509029 |
by way of a complete integration of the friedmann equations, in terms of observables, it is shown that for the cosmological constant $ \ lambda > 0 $ there exist non - flat flrw models for which the total density parameter $ \ omega $ remains $ \ sim 1 $ throughout the entire history of the universe. further, it is shown that in a precise quantitative sense these models are not finely tuned. when observations are brought to bear on the theory, and in particular the wmap observations, they confirm that we live in just such a universe. the conclusion holds when the classical notion of $ \ lambda $ is extended to dark energy. | arxiv:astro-ph/0404319 |
new dilaton weyl multiplets are constructed in four and five space - time dimensions for $ n = 4 $ and $ n = 2 $ conformal supergravity respectively. they are constructed from a mixture of the old dilaton weyl multiplets with an on - shell vector multiplet. the old dilaton weyl multiplets have a $ usp ( 4 ) $ r - symmetry group whereas the new multiplets have $ su ( 2 ) \ times su ( 2 ) $ r - symmetry, which is a subgroup of $ usp ( 4 ) $. in six dimensions, for the first time we construct a dilaton weyl multiplet for $ ( 2, 0 ) $ conformal supergravity from a mixture of the standard weyl multiplet and a tensor multiplet. the r - symmetry group for the dilaton weyl multiplet in six dimensions is also $ su ( 2 ) \ times su ( 2 ) $. | arxiv:2411.16322 |
this paper attacks the challenging problem of violence detection in videos. different from existing works focusing on combining multi - modal features, we go one step further by adding and exploiting subclasses visually related to violence. we enrich the mediaeval 2015 violence dataset by \ emph { manually } labeling violence videos with respect to the subclasses. such fine - grained annotations not only help understand what have impeded previous efforts on learning to fuse the multi - modal features, but also enhance the generalization ability of the learned fusion to novel test data. the new subclass based solution, with ap of 0. 303 and p100 of 0. 55 on the mediaeval 2015 test set, outperforms several state - of - the - art alternatives. notice that our solution does not require fine - grained annotations on the test set, so it can be directly applied on novel and fully unlabeled videos. interestingly, our study shows that motion related features, though being essential part in previous systems, are dispensable. | arxiv:1604.08088 |
in this paper there we describe the calculational background of deriving a strong meson lagrangian from the nambu - - jona - lasinio quark model using the computer algebra systems form and reduce in recursive algorithms, based on the heat - kernel method for the calculation of the quark determinant. | arxiv:hep-ph/9305329 |
the subject of this paper is a variation of a blackjack game, mainly popular in some parts of europe where it is known as einz ( in german slang : one ). we describe the rules of this game, indicate its main characteristics, give some probabilities, suggest the strategy, and consider some typical situations. | arxiv:1304.5455 |
the inelasticity in nucleus - nucleus collisions at high energies is calculated in the framework of geometrical multichain model. the very fast increase of the inelasticity is found as a result of a second - stage cascading process. the same behaviour is expected for all the models using the wounded nucleon idea. the simple formula for the number of wounded nucleons inside colliding nuclei does not need to be exact. | arxiv:hep-ph/9712416 |
the discrete efimov scaling behavior, well - known in the low - energy spectrum of three - body bound systems for large scattering lengths ( unitary limit ), is identified in the energy dependence of atom - molecule elastic cross - section in mass imbalanced systems. that happens in the collision of a heavy atom with mass $ m _ h $ with a weakly - bound dimer formed by the heavy atom and a lighter one with mass $ m _ l \ ll m _ h $. approaching the heavy - light unitary limit the $ s - $ wave elastic cross - section $ \ sigma $ will present a sequence of zeros / minima at collision energies following closely the efimov geometrical law. our results open a new perspective to detect the discrete scaling behavior from low - energy scattering data, which is timely in view of the ongoing experiments with ultra - cold binary mixtures having strong mass asymmetries, such as lithium and caesium or lithium and ytterbium. | arxiv:1708.00034 |
wireless sensor networks ( wsns ) are indispensable for data - intensive applications, necessitating efficient energy management and robust data fusion techniques. this paper proposes an integrated framework leveraging fuzzy logic and backpropagation neural networks ( bpnn ) to enhance energy efficiency and data accuracy in wsns. the model focuses on optimizing cluster head ( ch ) selection using fuzzy logic, considering parameters such as energy levels, proximity to the base station, and local density centrality. a minimum spanning tree ( mst ) algorithm is employed for energy - efficient data transmission from sensor nodes to chs, minimizing energy consumption during data routing. bpnn - based data fusion at chs reduces redundant data transmissions to the base station, thereby optimizing energy utilization and enhancing overall network performance. simulation results demonstrate substantial improvements over conventional methods, including a 30 % increase in network longevity, 25 % improvement in data accuracy, and a 40 % reduction in energy consumption. these gains are attributed to the intelligent ch selection strategy enabled by fuzzy logic, which ensures efficient resource allocation and minimizes energy wastage. the effectiveness of the proposed approach is validated through comprehensive simulations, showcasing its ability to prolong network lifetime, maintain data integrity, and improve energy efficiency. the integration of fuzzy logic and bpnn not only addresses the challenges of energy management and data fusion in wsns but also provides a scalable and adaptable framework for future applications requiring reliable and sustainable sensor network operations. the source code is available at https : / / github. com / hikomal / bpnn _ wsn. git | arxiv:2407.12806 |
based on a survey of the literature, we attempt to answer frequently asked questions on issues of cortical uniformity vs. non - uniformity, the neural mechanisms of symbolic variable binding, and other issues highlighted in ( marcus, marblestone and dean. " the atoms of neural computation ". science. 31 october 2014. vol 346. issue 6209 ). | arxiv:1410.8826 |
linear rate equations are used to describe the cascading decay of an initial heavy cluster into fragments. this representation is based upon a triangular matrix of transition rates. we expand the state vector of mass multiplicities, which describes the process, into the biorthonormal basis of eigenmodes provided by the triangular matrix. when the transition rates have a scaling property in terms of mass ratios at binary fragmentation vertices, we obtain solvable models with explicit mathematical properties for the eigenmodes. a suitable continuous limit provides an interpolation between the solvable models. it gives a general relationship between the decay products and the elementary transition rates. | arxiv:nucl-th/9412026 |
a quasigroup identity is of bol - moufang type if two of its three variables occur once on each side, the third variable occurs twice on each side, the order in which the variables appear on both sides is the same, and the only binary operation used is the multiplication, viz. $ ( ( xy ) x ) z = x ( y ( xz ) ) $. many well - known varieties of quasigroups are of bol - moufang type. we show that there are exactly 26 such varieties, determine all inclusions between them, and provide all necessary counterexamples. we also determine which of these varieties consist of loops or one - sided loops, and fully describe the varieties of commutative quasigroups of bol - moufang type. some of the proofs are computer - generated. | arxiv:math/0701715 |
we investigate imaging by spherically symmetric absolute instruments that provide perfect imaging in the sense of geometrical optics. we derive a number of properties of such devices, present a general method for designing them and use this method to propose several new absolute instruments, in particular a lens providing a stigmatic image of an optically homogeneous region and having a moderate refractive index range. | arxiv:1107.2524 |
we propose that the observed stellar halo around the globular cluster ( gc ) ngc 1851 is evidence for its formation in the central region of its defunct host dwarf galaxy. we numerically investigate the long - term dynamical evolution of a nucleated dwarf galaxy embedded in a massive dark matter halo under the strong tidal field of the galaxy. the dwarf galaxy is assumed to have a stellar nucleus ( or a nuclear star cluster ) that could be the progenitor for ngc 1851. we find that although the dark matter halo and the stellar envelope of the host dwarf of ngc 1851 can be almost completely stripped during its orbital evolution around the galaxy, a minor fraction of stars in the dwarf can remain trapped by the gravitational field of the nucleus. the stripped nucleus can be observed as ngc 1851 with no / little dark matter whereas stars around the nucleus can be observed as a diffuse stellar halo around ngc 1851. the simulated stellar halo has a symmetric distribution with a power - law density slope of ~ - 2 and shows no tidal tails within ~ 200pc from ngc 1851. we show that two gcs can merge with each other to form a new nuclear gc embedded in field stars owing to the low stellar velocity dispersion of the host dwarf. this result makes no assumption on the ages and / or chemical abundances of the two merging gcs. thus the observed stellar halo and characteristic multiple stellar populations in ngc 1851 suggest that ngc 1851 could have formed initially in the central region of an ancient dwarf galaxy. | arxiv:1109.4463 |
the purpose of this paper is to give two applications of fourier transforms and generic vanishing theorems : - we give a cohomological characterization of principal polarizations - we prove that if $ x $ an abelian variety and $ \ theta $ a polarization of type $ ( 1,..., 1, 2 ) $, then a general pair $ ( x, \ theta ) $ is log canonical | arxiv:math/9902078 |
we present a model for the observed hierarchies among the yukawa couplings of the standard model in the context of an effective low energy theory with an anomalous u ( 1 ) symmetry. this symmetry, a generic feature of superstring compactification, is a remnant of the green - schwarz anomaly cancellation mechanism. the gauge group is that of the standard model, augmented by x, the anomalous u ( 1 ), and two family - dependent phase symmetries $ y ^ { ( 1 ) } $ and $ y ^ { ( 2 ) } $. the correct hierarchies are reproduced only when $ sin ^ 2 \ theta _ w = 3 / 8 $ at the cut - off. to cancel anomalies, right - handed neutrinos and other standard model singlets must be introduced. independently of the charges of the right - handed neutrinos, this model produces the same neutrino mixing matrix and an inverted hierarchy of neutrino masses. the heaviest is the electron neutrino with a mass $ \ sim 1 $ mev, and mixing of the order of $ \ lambda _ c ^ 3 $ with each of the other two neutrinos. | arxiv:hep-ph/9705270 |
a new and simple analytical charge - control model of the two - dimensional electron gas of a double - heterojunction algaas / gaas / algaas hemt is described. it is found that, despite its simplicity, the charge - control model gives an accurate description of the device operation for a wide range of physical parameters. the validity of the analytical model is supported by the calculated results of the self - consistent quantum mechanical model and agrees with previously reported theoretical and experimental data. the influence of some physical parameters on the device performance is also discussed. | arxiv:cond-mat/0002092 |
in this work, we consider a non - quadratic dilaton $ \ phi ( z ) = ( \ kappa \, z ) ^ { 2 - \ alpha } $ in the context of the static soft wall model to describe the mass spectrum of a wide range of vector mesons from the light up to the heavy sectors. the effect of this non - quadratic approach is translated into non - linear regge trajectories with the generic form $ m ^ 2 = a \, ( n + b ) ^ \ nu $. we apply this sort of fits for the isovector states of $ \ omega $, $ \ phi $, $ j / \ psi $ and $ \ upsilon $ mesons and compare with the corresponding holographic duals. we also extend these ideas to the heavy - light sector by using the isovector set of parameters to extrapolate the proper values of $ \ kappa $ and $ \ alpha $ through the average constituent mass $ \ bar { m } $ for each mesonic specie considered. in the same direction, we address the description of possible non - $ q \, \ bar { q } $ candidates using $ \ bar { m } $ as a holographic threshold, associated with the structure of the exotic state, to define the values of $ \ kappa $ and $ \ alpha $. we study the $ \ pi _ 1 $ mesons in the light sector, and the $ z _ c $, $ y $ and $ z _ b $ mesons in the heavy sector as possible exotic vector states. finally, the rms error for describing these twenty - seven states with fifteen parameters ( four values for $ \ kappa $ and $ \ alpha $ respectively and seven values for $ \ bar { m } $ ) is $ 12. 61 \ % $. | arxiv:2004.10286 |
starting with a micropolar formulation, known to account for nonlocal microstructural effects at the continuum level, a generalized langevin equation ( gle ) for a particle, describing the predominant motion of a localized region through a single displacement degree - of - freedom ( dof ), is derived. the gle features a memory dependent multiplicative or internal noise, which appears upon recognising that the micro - rotation variables possess randomness owing to an uncertainty principle. unlike its classical version, the new gle qualitatively reproduces the experimentally measured fluctuations in the steady - state mean square displacement of scattering centers in a polyvinyl alcohol slab. the origin of the fluctuations is traced to nonlocal spatial interactions within the continuum. a constraint equation, similar to a fluctuation dissipation theorem ( fdt ), is shown to statistically relate the internal noise to the other parameters in the gle. | arxiv:1503.02772 |
for a proper subfield $ k $ of $ \ qq $ we show the existence of an algebraic number $ \ alpha $ such that no power $ \ alpha ^ n $, $ n \ geq 1 $, lies in $ k $. as an application it is shown that these numbers, multiplied by convenient gaussian numbers, can be written in the form $ p ( t ) ^ { q ( t ) } $ for some transcendental numbers $ t $ where $ p $ and $ q $ are arbitrarily prescribed non - constant rational functions over $ \ qq $. | arxiv:0901.1335 |
understanding and controlling interactions of ultracold molecules has been a central goal in quantum chemistry research. recent experiments on atoms near a feshbach resonance offer the key to prepare and investigate molecules in the quantum many - body regime. just as feshbach resonances allow tuning of the scattering length of bosonic atoms, we show that they also modify the scattering length of feshbach molecules which are constituted from these atoms. based on calculations of the compressibility, we determine the stability phase diagrams of molecular condensates and show that their instability can be associated with a sign change of the inter - molecular interactions. we derive universal expressions for the molecular scattering lengths, presented in terms of experimentally measurable quantities. these will enable control of interactions between feshbach molecules as well as further studies of few - and many - body reactions involving feshbach molecules in the quantum regime. | arxiv:2504.09183 |
assortment optimization is an important problem that arises in many industries such as retailing and online advertising where the goal is to find a subset of products from a universe of substitutable products which maximize seller ' s expected revenue. one of the key challenges in this problem is to model the customer substitution behavior. many parametric random utility maximization ( rum ) based choice models have been considered in the literature. however, in all these models, probability of purchase increases as we include more products to an assortment. this is not true in general and in many settings more choices hurt sales. this is commonly referred to as the choice overload. in this paper we attempt to address this limitation in rum through a generalization of the markov chain based choice model considered in blanchet et al. ( 2016 ). as a special case, we show that our model reduces to a generalization of mnl with no - purchase attractions dependent on the assortment s and strictly increasing with the size of assortment s. while we show that the assortment optimization under this model is np - hard, we present fully polynomial - time approximation scheme ( fptas ) under reasonable assumptions. | arxiv:1911.06716 |
angle - resolved photoemission spectroscopy ( arpes ) on optimally doped bi2sr2ca0. 92y0. 08cu2o ( 8 + delta ) uncovers a coupling of the electronic bands to a 40 mev mode in an extended k - space region away from the nodal direction, leading to a new interpretation of the strong renormalization of the electronic structure seen in bi2212. phenomenological agreements with neutron and raman experiments suggest that this mode is the b1g oxygen bond - buckling phonon. a theoretical calculation based on this assignment reproduces the electronic renormalization seen in the data. | arxiv:cond-mat/0403521 |
we show that the closure of the value set of a real linear recurrence sequence is the union of a countable set and a finite collection of intervals. conversely, any finite collection of closed intervals is the closure of the value set of some recurrence sequence. | arxiv:0903.4043 |
the energy loss of charged particles in silicon can be approximated by a simple analytical model. with help of measured charge deposits in individual channels of hit clusters their position and energy can be estimated. deposits below threshold and saturated values are treated properly, resulting in a wider dynamic range. the proposed method gives improvements on both hit position and energy residuals. the model is successfully applied to track differential energy loss estimation and to detector gain calibration tasks. | arxiv:1111.3213 |
detecting faces and heads appearing in video feeds are challenging tasks in real - world video surveillance applications due to variations in appearance, occlusions and complex backgrounds. recently, several cnn architectures have been proposed to increase the accuracy of detectors, although their computational complexity can be an issue, especially for real - time applications, where faces and heads must be detected live using high - resolution cameras. this paper compares the accuracy and complexity of state - of - the - art cnn architectures that are suitable for face and head detection. single pass and region - based architectures are reviewed and compared empirically to baseline techniques according to accuracy and to time and memory complexity on images from several challenging datasets. the viability of these architectures is analyzed with real - time video surveillance applications in mind. results suggest that, although cnn architectures can achieve a very high level of accuracy compared to traditional detectors, their computational cost can represent a limitation for many practical real - time applications. | arxiv:1809.03336 |
the main result provides an algorithm for determining the minimal free resolution of ideals of fat point subschemes of $ { \ bf p } ^ 2 $ involving up to 8 general points with arbitrary multiplicities ; the results hold over algebraically closed fields of any characteristic. the algorithm, which works by giving a formula in certain cases and a reduction to these cases otherwise, does not involve gr \ " obner bases, and so is very fast, even for very large multiplicities. partial information is also obtained in certain cases with $ n > 8 $. | arxiv:math/0101110 |
we present, ( partially ) analyze, and apply an efficient algorithm for the simulation of multivariate pareto records. a key role is played by minima of the record - setting region ( we call these generators ) each time a new record is generated, and two highlights of our work are ( i ) efficient dynamic maintenance of the set of generators and ( ii ) asymptotic analysis of the expected number of generators at each time. | arxiv:1901.05621 |
dynamic phase - only beam shaping with a liquid crystal spatial light modulator is a powerful technique for tailoring the beam ' s intensity profile or wave front. while shaping and controlling the light field is a highly researched topic, dynamic nonlinear beam shaping has hardly been explored so far. one potential reason is that generating the second harmonic is a degenerate process as it mixes two fields at the same frequency. to overcome this problem, we propose the use of type ii phase matching as a control mechanism to distinguish the two involved fields. we experimentally demonstrate that arbitrary intensity distributions can be shaped in the frequency - converted field at the same quality as for linear beam shaping and with conversion efficiencies similar to the case without beam shaping. we envision this technique as a milestone towards beam shaping beyond the physical limits of liquid crystal displays, i. e. facilitating dynamic phase - only beam shaping in the ultraviolet spectral range. | arxiv:2301.10093 |
bijectivization refines the yang - baxter equation into a pair of local markov moves which randomly update the configuration of the vertex model. employing this approach, we introduce new yang - baxter random fields of young diagrams based on spin $ q $ - whittaker and spin hall - littlewood symmetric functions. we match certain scalar markovian marginals of these fields with ( 1 ) the stochastic six vertex model ; ( 2 ) the stochastic higher spin six vertex model ; and ( 3 ) a new vertex model with pushing which generalizes the $ q $ - hahn pushtasep introduced recently by corwin - matveev - petrov ( arxiv : 1811. 06475 ). our matchings include models with two - sided stationary initial data, and we obtain fredholm determinantal expressions for the $ q $ - laplace transforms of the height functions of all these models. moreover, we also discover difference operators acting diagonally on spin $ q $ - whittaker or ( stable ) spin hall - littlewood symmetric functions. | arxiv:1905.06815 |
in scenarios where high penetration of renewable energy sources ( res ) is connected to the grid over long distances, the output of res exhibits significant fluctuations, making it difficult to accurately characterize. the intermittency and uncertainty of these fluctuations pose challenges to the stability of the power system. this paper proposes a distributionally robust damping optimization control framework ( drdoc ) to address the uncertainty in the true distribution of random disturbances caused by res. first, the installation location of damping controllers and key control parameters are determined through sobol sensitivity indices and participation factors. next, a nonlinear relationship between damping and random disturbances is established with polynomial chaos expansion ( pce ). the uncertainty in the distribution of disturbances is captured by ambiguity sets. the drdoc is formulated as a convex optimization problem, which is further simplified for efficient computation. finally, the optimal control parameters are derived through convex optimization techniques. simulation results demonstrate the effectiveness and distribution robustness of the proposed drdoc. | arxiv:2502.18840 |
let $ \ mathcal { o } $ be a closed orientable 2 - orbifold of negative euler characteristic. huebschmann constructed the atiyah - bott - goldman type symplectic form $ \ omega $ on the deformation space $ \ mathcal { c } ( \ mathcal { o } ) $ of convex projective structures on $ \ mathcal { o } $. we show that the deformation space $ \ mathcal { c } ( \ mathcal { o } ) $ of convex projective structures on $ \ mathcal { o } $ admits a global darboux coordinates system with respect to $ \ omega $. to this end, we show that $ \ mathcal { c } ( \ mathcal { o } ) $ can be decomposed into smaller symplectic spaces. in the course of the proof, we also study the deformation space $ \ mathcal { c } ( \ mathcal { o } ) $ for an orbifold $ \ mathcal { o } $ with boundary and construct the symplectic form on the deformation space of convex projective structures on $ \ mathcal { o } $ with fixed boundary holonomy. | arxiv:2007.13285 |
the use of deep learning has grown at an exponential rate, giving rise to numerous specialized hardware and software systems for deep learning. because the design space of deep learning software stacks and hardware accelerators is diverse and vast, prior work considers software optimizations separately from hardware architectures, effectively reducing the search space. unfortunately, this bifurcated approach means that many profitable design points are never explored. this paper instead casts the problem as hardware / software co - design, with the goal of automatically identifying desirable points in the joint design space. the key to our solution is a new constrained bayesian optimization framework that avoids invalid solutions by exploiting the highly constrained features of this design space, which are semi - continuous / semi - discrete. we evaluate our optimization framework by applying it to a variety of neural models, improving the energy - delay product by 18 % ( resnet ) and 40 % ( dqn ) over hand - tuned state - of - the - art systems, as well as demonstrating strong results on other neural network architectures, such as mlps and transformers. | arxiv:2010.02075 |
novel experimental modalities acquire spatially resolved velocity measurements for steady state and transient flows which are of interest for engineering and biological applications. one of the drawbacks of such high resolution velocity data is their susceptibility to measurement errors. in this paper, we propose a novel filtering strategy that allows enhancement of noisy measurements to obtain reconstruction of smooth divergence free velocity and corresponding pressure fields, which together approximately comply to a prescribed flow model. the main step in our approach consists of the appropriate use of the velocity measurements in the design of a linearized flow model which can be shown to be well - posed and consistent with the true velocity and pressure fields up to measurement and modeling errors. the reconstruction procedure is formulated as a linear quadratic optimal control problem and the resulting filter has analyzable smoothing and approximation properties. we also discuss briefly the discretization of our approach by finite element methods and comment on the efficient solution of the linear optimality system by iterative solvers. the capability of the proposed method to significantly reduce data noise is demonstrated by numerical tests in which we also compare to other methods like smoothing and solenoidal filtering. | arxiv:1512.08620 |
field programmable gate array ( fpga ) logic synthesis compilers ( e. g., vivado, iverilog, yosys, and quartus ) are widely applied in electronic design automation ( eda ), such as the development of fpga programs. however, defects ( i. e., incorrect synthesis ) in logic synthesis compilers may lead to unexpected behaviors in target applications, posing security risks. therefore, it is crucial to thoroughly test logic synthesis compilers to eliminate such defects. despite several hardware design language ( hdl ) code generators ( e. g., verismith ) have been proposed to find defects in logic synthesis compilers, the effectiveness of these generators is still limited by the simple code generation strategy and the monogeneity of the generated hdl code. this paper proposes legohdl, a novel method to generate syntax valid hdl code for comprehensively testing fpga logic synthesis compilers. legohdl can generate more complex and diverse defect - trigger hdl code ( e. g., verilog, vhdl, and systemverilog ) by leveraging the guidance of abstract syntax tree and the extensive function block libraries of cyber - physical systems. extensive experiments show that the diversity and defect - trigger capability of hdl code generated by legohdl are significantly better than the state - of - the - art method ( i. e., verismith ). in three months, legohdl has reported 20 new defects - - many of which are deep and important ; 16 of them have been confirmed. | arxiv:2407.12037 |
in this paper, we study a new moduli space $ \ mathcal { m } _ { n + 1 } ^ { \ mathrm { c } } $, which is obtained from $ \ mathcal { m } _ { 0, 2n + 2 } $ by identifying pairs of punctures. we find that this space is tiled by $ 2 ^ { n - 1 } n! $ cyclohedra, and construct the canonical form for each chamber. we also find the corresponding koba - nielsen factor can be viewed as the potential of the system of $ n { + } 1 $ pairs of particles on a circle, which is similar to the original case of $ \ mathcal { m } _ { 0, n } $ where the system is $ n { - } 3 $ particles on a line. we investigate the intersection numbers of chambers equipped with koba - nielsen factors. then we construct cyclohedra in kinematic space and show that the scattering equations serve as a map between the interior of worldsheet cyclohedron and kinematic cyclohedron. finally, we briefly discuss string - like integrals over such moduli space. | arxiv:1812.10727 |
we review recent pic simulation results which show that double - sided irradiaton of a thin overdense plasma slab by ultra - intense laser pulses from both sides can lead to sustained comoving acceleration of surface electrons to energies much higher than the conventional ponderomotive limit. the acceleration stops only when the electrons drift transversely out of the laser beam. we show results of parameter studies based on this concept and discuss future laser experiments that can be used to test these computer results. | arxiv:astro-ph/0603595 |
rota - - baxter operators $ r $ of weight $ 1 $ on $ \ mathfrak { n } $ are in bijective correspondence to post - lie algebra structures on pairs $ ( \ mathfrak { g }, \ mathfrak { n } ) $, where $ \ mathfrak { n } $ is complete. we use such rota - - baxter operators to study the existence and classification of post - lie algebra structures on pairs of lie algebras $ ( \ mathfrak { g }, \ mathfrak { n } ) $, where $ \ mathfrak { n } $ is semisimple. we show that for semisimple $ \ mathfrak { g } $ and $ \ mathfrak { n } $, with $ \ mathfrak { g } $ or $ \ mathfrak { n } $ simple, the existence of a post - lie algebra structure on such a pair $ ( \ mathfrak { g }, \ mathfrak { n } ) $ implies that $ \ mathfrak { g } $ and $ \ mathfrak { n } $ are isomorphic, and hence both simple. if $ \ mathfrak { n } $ is semisimple, but $ \ mathfrak { g } $ is not, it becomes much harder to classify post - lie algebra structures on $ ( \ mathfrak { g }, \ mathfrak { n } ) $, or even to determine the lie algebras $ \ mathfrak { g } $ which can arise. here only the case $ \ mathfrak { n } = \ mathfrak { sl } _ 2 ( \ bbb { c } ) $ was studied. in this paper we determine all lie algebras $ \ mathfrak { g } $ such that there exists a post - lie algebra structure on $ ( \ mathfrak { g }, \ mathfrak { n } ) $ with $ \ mathfrak { n } = \ mathfrak { sl } _ 2 ( \ bbb { c } ) \ oplus \ mathfrak { sl } _ 2 ( \ bbb { c } ) $. | arxiv:1805.05104 |
the bonferroni adjustment, or the union bound, is commonly used to study rate optimality properties of statistical methods in high - dimensional problems. however, in practice, the bonferroni adjustment is overly conservative. the extreme value theory has been proven to provide more accurate multiplicity adjustments in a number of settings, but only on ad hoc basis. recently, gaussian approximation has been used to justify bootstrap adjustments in large scale simultaneous inference in some general settings when $ n \ gg ( \ log p ) ^ 7 $, where $ p $ is the multiplicity of the inference problem and $ n $ is the sample size. the thrust of this theory is the validity of the gaussian approximation for maxima of sums of independent random vectors in high - dimension. in this paper, we reduce the sample size requirement to $ n \ gg ( \ log p ) ^ 5 $ for the consistency of the empirical bootstrap and the multiplier / wild bootstrap in the kolmogorov - smirnov distance, possibly in the regime where the gaussian approximation is not available. new comparison and anti - concentration theorems, which are of considerable interest in and of themselves, are developed as existing ones interweaved with gaussian approximation are no longer applicable. | arxiv:1705.09528 |
we prove that under the extended carleson ' s condition, a sequence $ ( x _ n ) \ subset b _ h $ is linear interpolating for $ h ^ { \ infty } ( b _ h ) $ for an infinite dimensional hilbert space h. in particular, we construct the interpolating functions for each sequence and find a bound for the constant of interpolation. | arxiv:1510.01529 |
we explore a new type of domain wall structure in ultrathin films with perpendicular anisotropy, that is influenced by the dzyaloshinskii - moriya interaction due to the adjacent layers. this study is performed by numerical and analytical micromagnetics. we show that these walls can behave like neel walls with very high stability, moving in stationary conditions at large velocities under large fields. we discuss the relevance of such walls, that we propose to call dzyaloshinskii domain walls, for current - driven domain wall motion under the spin hall effect. | arxiv:1211.5970 |
conditional image synthesis from layout has recently attracted much interest. previous approaches condition the generator on object locations as well as class labels but lack fine - grained control over the diverse appearance aspects of individual objects. gaining control over the image generation process is fundamental to build practical applications with a user - friendly interface. in this paper, we propose a method for attribute controlled image synthesis from layout which allows to specify the appearance of individual objects without affecting the rest of the image. we extend a state - of - the - art approach for layout - to - image generation to additionally condition individual objects on attributes. we create and experiment on a synthetic, as well as the challenging visual genome dataset. our qualitative and quantitative results show that our method can successfully control the fine - grained details of individual objects when modelling complex scenes with multiple objects. source code, dataset and pre - trained models are publicly available ( https : / / github. com / stanifrolov / attrlostgan ). | arxiv:2103.13722 |
gravitational waves ( gw ), as light, are gravitationally lensed by intervening matter, deflecting their trajectories, delaying their arrival and occasionally producing multiple images. in theories beyond general relativity ( gr ), new gravitational degrees of freedom add an extra layer of complexity and richness to gw lensing. we develop a formalism to compute gw propagation beyond gr over general space - times, including kinetic interactions with new fields. our framework relies on identifying the dynamical propagation eigenstates ( linear combinations of the metric and additional fields ) at leading order in a short - wave expansion. we determine these eigenstates and the conditions under which they acquire a different propagation speed around a lens. differences in speed between eigenstates cause birefringence phenomena, including time delays between the metric polarizations ( orthogonal superpositions of $ h _ +, h _ \ times $ ) observable without an electromagnetic counterpart. in particular, gw echoes are produced when the accumulated delay is larger than the signal ' s duration, while shorter time delays produce a scrambling of the wave - form. we also describe the formation of gw shadows as non - propagating metric components are sourced by the background of the additional fields around the lens. as an example, we apply our methodology to quartic horndeski theories with vainshtein screening and show that birefringence effects probe a region of the parameter space complementary to the constraints from the multi - messenger event gw170817. in the future, identified strongly lensed gws and binary black holes merging near dense environments, such as active galactic nuclei, will fulfill the potential of these novel tests of gravity. | arxiv:2009.12187 |
the standard client selection algorithms for federated learning ( fl ) are often unbiased and involve uniform random sampling of clients. this has been proven sub - optimal for fast convergence under practical settings characterized by significant heterogeneity in data distribution, computing, and communication resources across clients. for applications having timing constraints due to limited communication opportunities with the parameter server ( ps ), the client selection strategy is critical to complete model training within the fixed budget of communication rounds. to address this, we develop a biased client selection strategy, greedyfed, that identifies and greedily selects the most contributing clients in each communication round. this method builds on a fast approximation algorithm for the shapley value at the ps, making the computation tractable for real - world applications with many clients. compared to various client selection strategies on several real - world datasets, greedyfed demonstrates fast and stable convergence with high accuracy under timing constraints and when imposing a higher degree of heterogeneity in data distribution, systems constraints, and privacy requirements. | arxiv:2312.09108 |
are separated by more than 300 feet ( 91 m ) different floors on the same wing of a building in rooms that are horizontally offset by a minimum of 70 feet ( 21 m ) with fire walls between the rooms that are on different floors two rooms separated by another room, leaving at least a 70 - foot gap between the two rooms there should be a minimum of two separated fire walls and on opposite sides of a corridor geographic redundancy is used by amazon web services ( aws ), google cloud platform ( gcp ), microsoft azure, netflix, dropbox, salesforce, linkedin, paypal, twitter, facebook, apple icloud, cisco meraki, and many others to provide geographic redundancy, high availability, fault tolerance and to ensure availability and reliability for their cloud services. as another example, to minimize risk of damage from severe windstorms or water damage, buildings can be located at least 2 miles ( 3. 2 km ) away from the shore, with an elevation of at least 5 feet ( 1. 5 m ) above sea level. for additional protection, they can be located at least 100 feet ( 30 m ) away from flood plain areas. = = functions of redundancy = = the two functions of redundancy are passive redundancy and active redundancy. both functions prevent performance decline from exceeding specification limits without human intervention using extra capacity. passive redundancy uses excess capacity to reduce the impact of component failures. one common form of passive redundancy is the extra strength of cabling and struts used in bridges. this extra strength allows some structural components to fail without bridge collapse. the extra strength used in the design is called the margin of safety. eyes and ears provide working examples of passive redundancy. vision loss in one eye does not cause blindness but depth perception is impaired. hearing loss in one ear does not cause deafness but directionality is lost. performance decline is commonly associated with passive redundancy when a limited number of failures occur. active redundancy eliminates performance declines by monitoring the performance of individual devices, and this monitoring is used in voting logic. the voting logic is linked to switching that automatically reconfigures the components. error detection and correction and the global positioning system ( gps ) are two examples of active redundancy. electrical power distribution provides an example of active redundancy. several power lines connect each generation facility with customers. each power line includes monitors that detect overload. each power line also includes circuit breakers. the | https://en.wikipedia.org/wiki/Redundancy_(engineering) |
as a novel technology, cloud computing attracts more and more people including technology enthusiasts and malicious users. different from the classical network architecture, cloud environment has many its own features which make the traditional defense mechanism invalid. to make the network more robust against a malicious attack, we introduce a new method to mitigate this risk efficiently and systematically. in this paper, we first propose a coupled networks model which adequately considers the interactions between physical layer and virtual layer in a practical cloud computing environment. based on this new model and our systematical method, we show that with the addition of protection of some specific nodes in the network structure, the robustness of cloud computing ' s network can be significantly improved whereas their functionality remains unchanged. our results demonstrate that our new method can effectively settle the hard problems which cloud computing now is facing without much cost. | arxiv:1512.02756 |
kinetic theory ( kt ) has been successfully used to model rapid granular flows in which particle interactions are frictionless and near elastic. however, it fails when particle interactions become frictional and inelastic. for example, the kt is not able to accurately predict the free cooling process of a vibrated granular medium that consists of inelastic frictional particles under microgravity. the main reason that the classical kt fails to model these flows is due to its inability to account for the particle surface friction and its inelastic behavior, which are the two most important factors that need be considered in modeling collisional granular flows. in this study, we have modified the kt model that is able to incorporate these two factors. the inelasticity of a particle is considered by establishing a velocity - dependent expression for the restitution coefficient based on many experimental studies found in the literature, and the particle friction effect is included by using a tangential restitution coefficient that is related to the particle friction coefficient. theoretical predictions of the free cooling process by the classical kt and the improved kt are compared with the experimental results from a study conducted on an airplane undergoing parabolic flights without the influence of gravity [ y. grasselli, g. bossis, and g. goutallier, epl ( europhysics letters ) 86, 60007 ( 2009 ) ]. our results show that both the velocity - dependent restitution coefficient and the particle surface friction are important in predicting the free cooling process of granular flows ; the modified kt model that integrates these two factors is able to improve the simulation results and led to a better agreement with the experimental results. | arxiv:1712.02946 |
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