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font selection is one of the most important steps in a design workflow. traditional methods rely on ordered lists which require significant domain knowledge and are often difficult to use even for trained professionals. in this paper, we address the problem of large - scale tag - based font retrieval which aims to bring semantics to the font selection process and enable people without expert knowledge to use fonts effectively. we collect a large - scale font tagging dataset of high - quality professional fonts. the dataset contains nearly 20, 000 fonts, 2, 000 tags, and hundreds of thousands of font - tag relations. we propose a novel generative feature learning algorithm that leverages the unique characteristics of fonts. the key idea is that font images are synthetic and can therefore be controlled by the learning algorithm. we design an integrated rendering and learning process so that the visual feature from one image can be used to reconstruct another image with different text. the resulting feature captures important font design details while is robust to nuisance factors such as text. we propose a novel attention mechanism to re - weight the visual feature for joint visual - text modeling. we combine the feature and the attention mechanism in a novel recognition - retrieval model. experimental results show that our method significantly outperforms the state - of - the - art for the important problem of large - scale tag - based font retrieval. | arxiv:1909.02072 |
we construct the symplectic resolution of a symplectic orbifold whose isotropy locus consists of disjoint submanifolds with homogeneous isotropy, that is, all its points have the same isotropy groups. | arxiv:1805.01160 |
let $ \ delta \ in ( 0, 1 ] $ and $ t $ be a $ \ delta $ - calder \ ' on - zygmund operator. let $ w $ be in the muckenhoupt class $ a _ { 1 + \ delta / n } ( { \ mathbb r } ^ n ) $ satisfying $ \ int _ { { \ mathbb r } ^ n } \ frac { w ( x ) } { 1 + | x | ^ n } \, dx < \ infty $. when $ b \ in { \ rm bmo } ( \ mathbb r ^ n ) $, it is well known that the commutator $ [ b, t ] $ is not bounded from $ h ^ 1 ( \ mathbb r ^ n ) $ to $ l ^ 1 ( \ mathbb r ^ n ) $ if $ b $ is not a constant function. in this article, the authors find out a proper subspace $ { \ mathop \ mathcal { bmo } _ w ( { \ mathbb r } ^ n ) } $ of $ \ mathop \ mathrm { bmo } ( \ mathbb r ^ n ) $ such that, if $ b \ in { \ mathop \ mathcal { bmo } _ w ( { \ mathbb r } ^ n ) } $, then $ [ b, t ] $ is bounded from the weighted hardy space $ h _ w ^ 1 ( \ mathbb r ^ n ) $ to the weighted lebesgue space $ l _ w ^ 1 ( \ mathbb r ^ n ) $. conversely, if $ b \ in { \ rm bmo } ( { \ mathbb r } ^ n ) $ and the commutators of the classical riesz transforms $ \ { [ b, r _ j ] \ } _ { j = 1 } ^ n $ are bounded from $ h ^ 1 _ w ( { \ mathbb r } ^ n ) $ into $ l ^ 1 _ w ( { \ mathbb r } ^ n ) $, then $ b \ in { \ mathop \ mathcal { bmo } _ w ( { \ mathbb r } ^ n ) } $. | arxiv:1510.05855 |
classical entanglement is a powerful tool which provides a neat numerical estimate for the study of classical correlations. its experimental investigation, however, has been limited to special cases. here, we demonstrate that the experimental quantification of the level of classical entanglement can be carried out in more general instances. our approach enables the extension to arbitrarily shaped transverse modes and hence delivering a suitable quantification tool to describe concisely the modal structure. | arxiv:1612.03697 |
a number of ultra - cool dwarfs emit circularly polarised radio waves generated by the electron cyclotron maser instability. in the solar system such radio is emitted from regions of strong auroral magnetic field - aligned currents. we thus apply ideas developed for jupiter ' s magnetosphere, being a well - studied rotationally - dominated analogue in our solar system, to the case of fast - rotating ucds. we explain the properties of the radio emission from ucds by showing that it would arise from the electric currents resulting from an angular velocity shear in the fast - rotating magnetic field and plasma, i. e. by an extremely powerful analogue of the process which causes jupiter ' s auroras. such a velocity gradient indicates that these bodies interact significantly with their space environment, resulting in intense auroral emissions. these results strongly suggest that auroras occur on bodies outside our solar system. | arxiv:1210.1864 |
we prove strengthened lower bounds for constant - depth set - multilinear formulas. more precisely, we show that over any field, there is an explicit polynomial $ f $ in vnp defined over $ n ^ 2 $ variables, and of degree $ n $, such that any product - depth $ \ delta $ set - multilinear formula computing $ f $ has size at least $ n ^ { \ omega \ left ( n ^ { 1 / \ delta } / \ delta \ right ) } $. the hard polynomial $ f $ comes from the class of nisan - wigderson ( nw ) design - based polynomials. our lower bounds improve upon the recent work of limaye, srinivasan and tavenas ( stoc 2022 ), where a lower bound of the form $ ( \ log n ) ^ { \ omega ( \ delta n ^ { 1 / \ delta } ) } $ was shown for the size of product - depth $ \ delta $ set - multilinear formulas computing the iterated matrix multiplication ( imm ) polynomial of the same degree and over the same number of variables as $ f $. moreover, our lower bounds are novel for any $ \ delta \ geq 2 $. for general set - multilinear formulas, a lower bound of the form $ n ^ { \ omega ( \ log n ) } $ was already obtained by raz ( j. acm 2009 ) for the more general model of multilinear formulas. the techniques of lst give a different route to set - multilinear formula lower bounds, and allow them to obtain a lower bound of the form $ ( \ log n ) ^ { \ omega ( \ log n ) } $ for the size of general set - multilinear formulas computing the imm polynomial. our proof techniques are another variation on those of lst, and enable us to show an improved lower bound ( matching that of raz ) of the form $ n ^ { \ omega ( \ log n ) } $, albeit for the same polynomial $ f $ in vnp ( the nw polynomial ). as observed by lst, if the same $ n ^ { \ omega ( \ log n ) } $ size lower bounds for unbounded - depth set - multilinear formulas could be obtained for the imm polynomial, then using the self - reducibility of imm and using hardness escalation results, this would imply super - polynomial lower bounds for general algebraic formulas. | arxiv:2205.00611 |
we define a module that is an extension of the diagonal harmonics and whose graded frobenius characteristic is conjectured to be the symmetric function expression which appears in ` the delta conjecture ' of haglund, remmel and wilson [ arxiv : 1509. 07058 ]. | arxiv:1902.08966 |
we explore a plausible mechanism that the hemispherical power asymmetry in the cmb is produced by the spatial variation of the primordial sound speed parameter. we suggest that in a generalized approach of the $ \ delta n $ formalism the local e - folding number may depend on some other primordial parameters besides the initial values of inflaton. here the $ \ delta n $ formalism is extended by considering the effects of a spatially varying sound speed parameter caused by a super - hubble perturbation of a light field. using this generalized $ \ delta n $ formalism, we systematically calculate the asymmetric primordial spectrum in the model of multi - speed inflation by taking into account the constraints of primordial non - gaussianities. we further discuss specific model constraints, and the corresponding asymmetry amplitudes are found to be scale - dependent, which can accommodate current observations of the power asymmetry at different length scales. | arxiv:1509.02541 |
influence of surface pair breaking, barrier transmission and phase difference on quasiparticle bound states in junctions with d - wave superconductors is examined. based on the quasiclassical theory of superconductivity, an approach is developed to handle interface bound states. it is shown in sis ' junctions that low energy bound states get their energies reduced by surface pair breaking, which can be taken into account by introducing an effective order parameter for each superconductor at the junction barrier. more interestingly, for the interface bound states near the continuous spectrum the effect of surface pair breaking may result in a splitting of the bound states. in the tunneling limit this can lead to a square root dependence of a nonequilibrium josephson current on the barrier transmision, which means an enhancement as compared to the conventional critical current linear in the transmission. reduced broadening of bound states in nis junctions due to surface pair breaking is found. | arxiv:cond-mat/9907277 |
we analyze the crystallization and collapse transition of a simple model for flexible polymer chains on simple cubic and face - centered cubic lattices by means of sophisticated chain - growth methods. in contrast to bond - fluctuation polymer models in certain parameter ranges, where these two conformational transitions were found to merge in the thermodynamic limit, we conclude from our results that the two transitions remain well - separated in the limit of infinite chain lengths. the reason for this qualitatively distinct behavior is presumably due to the ultrashort attractive interaction range in the lattice models considered here. | arxiv:0710.4960 |
we characterize the oriented seifert - fibered three - manifolds which admit positive, transverse contact structures. | arxiv:math/0405329 |
we first analyze the recent experimental data on the nuclear spin - lattice relaxation rate of the weyl semimetal tap. we argue that its non - monotonic temperature dependence is explained by the temperature dependent chemical potential of weyl fermions. we also develop the theory of the knight shift in weyl semimetals, which contains two counteracting terms. the diamagnetic term follows $ - \ ln [ w / \ max ( | \ mu |, k _ bt ) ] $ with $ w $, $ \ mu $ and $ t $ being the high energy cutoff, chemical potential and temperature, respectively, and is always negative. the paramagnetic term scales with $ \ mu $ and changes sign depending on the doping level. altogether, the knight shift is predicted to vanish or even change sign upon changing the doping or the temperature, making it a sensitive tool to identify weyl points. we also calculate the korringa relation for weyl semimetals which shows an unusual energy dependence rather than being constant as expected for a non - interacting fermi system. | arxiv:1806.08163 |
we propose to use high numerical aperture single mode optical fibers like photonic crystal fiber for lensless in - line holographic microscopy. highly divergent beam helps to overcome the spatial sampling limitation of the image sensor. in this paper, a submicron lateral resolution has been demonstrated, with an imaging sensor of pixel pitch 1. 12 micrometer and a photonic crystal fiber of mode field diameter 1. 8 micrometer. in earlier methods of single - shot lensless imaging, submicron resolution has been obtained at very small working distance and field of view. the proposed method improves the resolution without compromising the working distance. a working distance of ( but not limited to ) ~ 1. 7 mm with a field of view ~ 1. 4 mm has been demonstrated. | arxiv:2001.09867 |
computer vision using deep neural networks ( dnns ) has brought about seminal changes in people ' s lives. applications range from automotive, face recognition in the security industry, to industrial process monitoring. in some cases, dnns infer even in safety - critical situations. therefore, for practical applications, dnns have to behave in a robust way to disturbances such as noise, pixelation, or blur. blur directly impacts the performance of dnns, which are often approximated as a disk - shaped kernel to model defocus. however, optics suggests that there are different kernel shapes depending on wavelength and location caused by optical aberrations. in practice, as the optical quality of a lens decreases, such aberrations increase. this paper proposes opticsbench, a benchmark for investigating robustness to realistic, practically relevant optical blur effects. each corruption represents an optical aberration ( coma, astigmatism, spherical, trefoil ) derived from zernike polynomials. experiments on imagenet show that for a variety of different pre - trained dnns, the performance varies strongly compared to disk - shaped kernels, indicating the necessity of considering realistic image degradations. in addition, we show on imagenet - 100 with opticsaugment that robustness can be increased by using optical kernels as data augmentation. compared to a conventionally trained resnext50, training with opticsaugment achieves an average performance gain of 21. 7 % points on opticsbench and 6. 8 % points on 2d common corruptions. | arxiv:2308.15499 |
icecube deepcore is an extension of the icecube neutrino observatory designed to measure gev scale atmospheric neutrino interactions for the purpose of neutrino oscillation studies. distinguishing muon neutrinos from other flavors and reconstructing inelasticity are especially difficult tasks at gev scale energies in icecube deepcore due to sparse instrumentation. convolutional neural networks ( cnns ) have been found to have better success at neutrino event reconstruction than conventional likelihood - based methods. in this contribution, we present a new cnn model that exploits time and depth translational symmetry in icecube deepcore data and present the model ' s performance, specifically for flavor identification and inelasticity reconstruction. | arxiv:2307.16373 |
recently, encoders like vit ( vision transformer ) and resnet have been trained on vast datasets and utilized as perceptual metrics for comparing sketches and images, as well as multi - domain encoders in a zero - shot setting. however, there has been limited effort to quantify the granularity of these encoders. our work addresses this gap by focusing on multi - modal 2d projections of individual 3d instances. this task holds crucial implications for retrieval and sketch - based modeling. we show that in a zero - shot setting, the more abstract the sketch, the higher the likelihood of incorrect image matches. even within the same sketch domain, sketches of the same object drawn in different styles, for example by distinct individuals, might not be accurately matched. one of the key findings of our research is that meticulous fine - tuning on one class of 3d shapes can lead to improved performance on other shape classes, reaching or surpassing the accuracy of supervised methods. we compare and discuss several fine - tuning strategies. additionally, we delve deeply into how the scale of an object in a sketch influences the similarity of features at different network layers, helping us identify which network layers provide the most accurate matching. significantly, we discover that vit and resnet perform best when dealing with similar object scales. we believe that our work will have a significant impact on research in the sketch domain, providing insights and guidance on how to adopt large pretrained models as perceptual losses. | arxiv:2306.08541 |
community detection in social networks is a problem with considerable interest, since, discovering communities reveals hidden information about networks. there exist many algorithms to detect inherent community structures and recently few of them are investigated on social networks. however, it is non - trivial to decide the best approach in the presence of diverse nature of graphs, in terms of density and sparsity, and inadequate analysis of the results. therefore, in this study, we analyze and compare various algorithms to detect communities in two networks, namely social and road networks, with varying structural properties. the algorithms under consideration are evaluated with unique metrics for internal and external connectivity of communities that includes internal density, average degree, cut ratio, conductance, normalized cut, and average jaccard index. the evaluation results revealed key insights about selected algorithms and underlying community structures. | arxiv:1911.08992 |
we describe a family of half - line continuum schroedinger operators with purely singular continuous essential spectrum, exhibiting asymptotic strong level repulsion ( known as clock behavior ). this follows from the convergence of the renormalized continuum christoffel - darboux kernel to the sine kernel. | arxiv:1612.01123 |
we present a series of numerical sunspot models addressing the subsurface field and flow structure in up to 16 mm deep domains covering up to 2 days of temporal evolution. changes in the photospheric appearance of the sunspots are driven by subsurface flows in several mm depth. most of magnetic field is pushed into a downflow vertex of the subsurface convection pattern, while some fraction of the flux separates from the main trunk of the spot. flux separation in deeper layers is accompanied in the photosphere with light bridge formation in the early stages and formation of pores separating from the spot at later stages. over a time scale of less than a day we see the development of a large scale flow pattern surrounding the sunspots, which is dominated by a radial outflow reaching about 50 % of the convective rms velocity in amplitude. several components of the large scale flow are found to be independent from the presence of a penumbra and the associated evershed flow. while the simulated sunspots lead to blockage of heat flux in the near surface layers, we do not see compelling evidence for a brightness enhancement in their periphery. we further demonstrate that the influence of the bottom boundary condition on the stability and long - term evolution of the sunspot is significantly reduced in a 16 mm deep domain compared to the shallower domains considered previously. | arxiv:1106.6287 |
kasparov $ kk $ - groups $ kk ( a, b ) $ are represented as homotopy groups of the pedersen - weibel nonconnective algebraic $ k $ - theory spectrum of the additive category of fredholm $ ( a, b ) $ - bimodules for $ a $ and $ b $, respectively, a separable and $ \ sigma $ - unital trivially graded real or complex $ c ^ * $ - algebra acted upon by a fixed compact metrizable group. | arxiv:math/0609208 |
we extend the hotspot lemma, or piatetski \ u { i } - shapiro normality criterion, to dynamical systems on non - compact spaces. we build on the work of n. g. moshchevitin and i. d. shkredov, noting an issue in some of their proofs, and adding a necessary and sufficient condition to remove this issue. | arxiv:1912.10265 |
the paper is devoted to discretization of integral norms of functions from a given collection of finite dimensional subspaces. for natural collections of subspaces of the multivariate trigonometric polynomials we construct sets of points, which are optimally ( in the sense of order ) good for each subspace of a collection from the point of view of the integral norm discretization. we call such sets universal. our construction of the universal sets is based on deep results on existence of special nets, known as ( t, r, d ) - nets. | arxiv:1708.08544 |
fabrication technology, which allows a substantial decrease of the plasmonic propagation loss for both plasmon - friendly metals like au, cu or al and plasmon - unfriendly metals like co, fe or cr, has been developed and experimentally demonstrated. optimization of the optical confinement is used to reduce the propagation loss below 1 db per plasmonic device. | arxiv:2212.04112 |
the recognition and understanding of traffic incidents, particularly traffic accidents, is a topic of paramount importance in the realm of intelligent transportation systems and intelligent vehicles. this area has continually captured the extensive focus of both the academic and industrial sectors. identifying and comprehending complex traffic events is highly challenging, primarily due to the intricate nature of traffic environments, diverse observational perspectives, and the multifaceted causes of accidents. these factors have persistently impeded the development of effective solutions. the advent of large vision - language models ( vlms ) such as gpt - 4v, has introduced innovative approaches to addressing this issue. in this paper, we explore the ability of gpt - 4v with a set of representative traffic incident videos and delve into the model ' s capacity of understanding these complex traffic situations. we observe that gpt - 4v demonstrates remarkable cognitive, reasoning, and decision - making ability in certain classic traffic events. concurrently, we also identify certain limitations of gpt - 4v, which constrain its understanding in more intricate scenarios. these limitations merit further exploration and resolution. | arxiv:2402.02205 |
in this work, we generalize the problem of learning through interaction in a pomdp by accounting for eventual additional information available at training time. first, we introduce the informed pomdp, a new learning paradigm offering a clear distinction between the information at training and the observation at execution. next, we propose an objective that leverages this information for learning a sufficient statistic of the history for the optimal control. we then adapt this informed objective to learn a world model able to sample latent trajectories. finally, we empirically show a learning speed improvement in several environments using this informed world model in the dreamer algorithm. these results and the simplicity of the proposed adaptation advocate for a systematic consideration of eventual additional information when learning in a pomdp using model - based rl. | arxiv:2306.11488 |
previous studies of the flexibilities of ancestral proteins suggests that proteins evolve their function by altering their native state ensemble. here we propose a more direct method of visualizing this by measuring the changes in the vibrational density of states ( vdos ) of proteins as they evolve. through analysis of vdos profiles of ancestral and extant proteins we observe that $ \ beta $ - lactamase and thioredoxins evolve by altering their density of states in the terahertz region. particularly, the shift in vdos profiles between ancestral and extant proteins suggests that nature utilize dynamic allostery for functional evolution. moreover, we also show that vdos profile of individual position can be used to describe the flexibility changes, particularly those without any amino acid substitution. | arxiv:2109.07004 |
in this paper, we investigate properties of automorphism groups of function fields in one variable in relation to its reductions with respect to special valuations. in 1969, deligne and mumford proved that there exists a natural injective homomorphism between the automorphism groups of $ \ mathcal { x } _ { \ eta } $ and any special fibre of $ \ mathcal { x }. $ here, we give a generalisation of this theorem in function field setting of deuring ' s theory of constant reductions. | arxiv:1601.07998 |
we investigate the detectability of gravitational waves that have been lensed by a spinless stellar - mass black hole, with respect to the advanced ligo. by solving the full relativistic linear wave equations in the spacetime of a schwarzschild black hole, we find that the strong gravity can create unique signals in the lensed waveform, particularly during the merger and ringdown stages. the differences in terms of fitting factor between the lensed waveform and best - fitted unlensed general relativity template with spin - precessing and higher - order multipoles are greater than $ 5 \ % $ for the lens black hole mass within $ 70m _ { \ odot } < m _ { \ rm lens } < 133. 33 m _ { \ odot } $ under advanced ligo ' s sensitivity. this is up to 5 times more detectable than the previous analysis based on the weak field approximation for a point mass and covers most part of the black hole mass gap predicted by stellar evolution theory. based on bayesian inference, the lensing feature can be distinguished with a signal - to - noise ratio of 12. 5 for $ m _ { \ rm lens } = 70 m _ { \ odot } $ and 19. 2 for $ m _ { \ rm lens } = 250 m _ { \ odot } $, which is attainable for advanced ligo. | arxiv:2312.12451 |
in 1989, thomassen asked whether there is an integer - valued function f ( k ) such that every f ( k ) - connected graph admits a spanning, bipartite $ k $ - connected subgraph. in this paper we take a first, humble approach, showing the conjecture is true up to a log n factor. | arxiv:1410.4902 |
with the rapid progression of deep learning technologies, multi - modality image fusion has become increasingly prevalent in object detection tasks. despite its popularity, the inherent disparities in how different sources depict scene content make fusion a challenging problem. current fusion methodologies identify shared characteristics between the two modalities and integrate them within this shared domain using either iterative optimization or deep learning architectures, which often neglect the intricate semantic relationships between modalities, resulting in a superficial understanding of inter - modal connections and, consequently, suboptimal fusion outcomes. to address this, we introduce a text - guided multi - modality image fusion method that leverages the high - level semantics from textual descriptions to integrate semantics from infrared and visible images. this method capitalizes on the complementary characteristics of diverse modalities, bolstering both the accuracy and robustness of object detection. the codebook is utilized to enhance a streamlined and concise depiction of the fused intra - and inter - domain dynamics, fine - tuned for optimal performance in detection tasks. we present a bilevel optimization strategy that establishes a nexus between the joint problem of fusion and detection, optimizing both processes concurrently. furthermore, we introduce the first dataset of paired infrared and visible images accompanied by text prompts, paving the way for future research. extensive experiments on several datasets demonstrate that our method not only produces visually superior fusion results but also achieves a higher detection map over existing methods, achieving state - of - the - art results. | arxiv:2401.00421 |
terahertz radiation by optical rectification has been observed at room temperature in a hydrogen - bonded organic molecular ferroelectric crystal, 2 - phenyl malondialdehyde ( phmda ). the radiated electromagnetic wave consisted of a single - cycle terahertz pulse with a temporal width of $ \ sim $ 0. 5 ps. the terahertz radiation amplitude divided by the sample thickness in phmda was nearly equivalent to that in a typical terahertz wave emitter znte. this is attributable to a long coherence length in the range of 130 $ \ sim $ 800 $ \ mu $ m for the terahertz radiation from phmda. we also discussed the possibility of phmda as a terahertz wave emitter in terms of the phase - matching condition. | arxiv:1409.2958 |
macrocycles have attracted much attention due to their specific " endless " topology, which results in extraordinary properties compared to related linear ( open - chain ) molecules. however, challenges still remain in their controlled synthesis with well - defined constitution and geometry. here, we report the first successful application of the ( pseudo - ) high dilution method to the conditions of on - surface synthesis in ultrahigh vacuum ( uhv ). this approach leads to high yields ( up to 84 % ) of cyclic hyperbenzene ( [ 18 ] - honeycombene ) via an ullmann - type reaction from 4, 4 " - dibromo - meta - terphenyl ( dmtp ) as precursor on a ag ( 111 ) surface. the mechanism of macrocycle formation was explored in detail using scanning tunneling microscopy ( stm ) and x - ray photoemission spectroscopy ( xps ). we propose that hyperbenzene ( mtp ) 6 forms majorly by stepwise desilverization of an organometallic ( mtp - ag ) 6 macrocycle, which preforms via cyclisation of ( mtp - ag ) 6 chains under pseudo - high dilution condition. the high probability of cyclisation on the stage of the organometallic phase results from the reversibility of the c - ag bond. the case is different from that in solution, in which cyclisation typically occurs on the stage of covalently bonded open - chain precursor. this difference in the cyclisation mechanism on a surface compared to that in solution stems mainly from the 2d confinement exerted by the surface template, which to a large extent prevents the flipping of chain segments necessary for cyclisation. | arxiv:1703.10018 |
several explanations for the existence of ultra high energy cosmic rays invoke the idea that they originate from the decay of massive particles created in the reheating following inflation. it has been suggested that the decay products can explain the observed isotropic flux of cosmic rays. we have calculated the anisotropy expected for various models of the dark matter distribution and find that at present data are too sparse above $ 4 \ times 10 ^ { 19 } $ ev to discriminate between different models. however we show that with data from three years of operation of the southern section of the pierre auger observatory significant progress in testing the proposals will be made. | arxiv:astro-ph/9903182 |
in the segmentation of fine - scale structures from natural and biomedical images, per - pixel accuracy is not the only metric of concern. topological correctness, such as vessel connectivity and membrane closure, is crucial for downstream analysis tasks. in this paper, we propose a new approach to train deep image segmentation networks for better topological accuracy. in particular, leveraging the power of discrete morse theory ( dmt ), we identify global structures, including 1d skeletons and 2d patches, which are important for topological accuracy. trained with a novel loss based on these global structures, the network performance is significantly improved especially near topologically challenging locations ( such as weak spots of connections and membranes ). on diverse datasets, our method achieves superior performance on both the dice score and topological metrics. | arxiv:2103.09992 |
image - to - video person re - identification identifies a target person by a probe image from quantities of pedestrian videos captured by non - overlapping cameras. despite the great progress achieved, it ' s still challenging to match in the multimodal scenario, i. e. between image and video. currently, state - of - the - art approaches mainly focus on the task - specific data, neglecting the extra information on the different but related tasks. in this paper, we propose an end - to - end neural network framework for image - to - video person reidentification by leveraging cross - modal embeddings learned from extra information. concretely speaking, cross - modal embeddings from image captioning and video captioning models are reused to help learned features be projected into a coordinated space, where similarity can be directly computed. besides, training steps from fixed model reuse approach are integrated into our framework, which can incorporate beneficial information and eventually make the target networks independent of existing models. apart from that, our proposed framework resorts to cnns and lstms for extracting visual and spatiotemporal features, and combines the strengths of identification and verification model to improve the discriminative ability of the learned feature. the experimental results demonstrate the effectiveness of our framework on narrowing down the gap between heterogeneous data and obtaining observable improvement in image - to - video person re - identification. | arxiv:1810.03989 |
we investigate the effect of free electrons on the quality factor ( q ) of a metallic nanomechanical resonator in the form of a thin elastic beam. the flexural and longitudinal modes of the beam are modeled using thin beam elasticity theory, and simple perturbation theory is used to calculate the rate at which an externally excited vibration mode decays due to its interaction with free electrons. we find that electron - phonon interaction significantly affects the q of longitudinal modes, and may also be of significance to the damping of flexural modes in otherwise high - q beams. the finite geometry of the beam is manifested in two important ways. its finite length breaks translation invariance along the beam and introduces an imperfect momentum conservation law in place of the exact law. its finite width imposes a quantization of the electronic states that introduces a temperature scale for which there exists a crossover from a high - temperature macroscopic regime, where electron - phonon damping behaves as if the electrons were in the bulk, to a low - temperature mesoscopic regime, where damping is dominated by just a few dissipation channels and exhibits sharp non - monotonic changes as parameters are varied. this suggests a novel scheme for probing the electronic spectrum of a nanoscale device by measuring the q of its mechanical vibrations. | arxiv:1211.0450 |
in our previous researches, a new digital watermarking scheme based on chaotic iterations has been introduced. this scheme was both stego - secure and topologically secure. the stego - security is to face an attacker in the " watermark only attack " category, whereas the topological security concerns other categories of attacks. its lyapunov exponent is evaluated here, to quantify the chaos generated by this scheme. keywords : lyapunov exponent ; information hiding ; security ; chaotic iterations ; digital watermarking. | arxiv:1203.0692 |
avatr technology co., ltd. ( chinese : 阿 ; pinyin : a wei ta ; pronounced " avatar " ) is a chinese electric vehicle manufacturer headquartered in chongqing. established in 2018, avatr technology is a premium ev brand created through a joint venture led by changan automobile in collaboration with various chinese domestic entities. the brand benefits from technological support provided by huawei and battery technology supplied by catl. = = history = = = = = changan - nio = = = in 2018, changan aimed to establish a company dedicated to developing modern, technologically advanced electric vehicles in partnership with nio inc. to achieve this, a joint venture named changan - nio was formed with an equal 50 : 50 share ratio. however, the partnership did not materialize, as nio withdrew from the alliance two years later. = = = establishment of avatr = = = following nio ' s withdrawal, changan automobile as the primary shareholder partnered with two major chinese technology companies : battery manufacturer catl and technology corporation huawei. in may 2021, the company was renamed from changan - nio to avatr technology. in november 2021, avatr conducted its first round of capital increase and share expansion, resulting in a dilution of changan automobile ' s ownership from 95. 38 % to 39. 02 %. catl acquired a 23. 99 % stake, while the remaining shares were held by various investment entities. although huawei did not become a shareholder, it collaborated closely with avatr, providing comprehensive technological solutions. in august 2022, avatr initiated its series a funding round, attracting three additional investors supported by chinese private enterprises and local governments. the total financing scale reached nearly 5 billion yuan. as a result, changan automobile ' s ownership stake increased from 39. 02 % to 40. 99 %. catl, which did not participate in the capital increase, saw its ownership stake diluted from 23. 99 % to 17. 10 %. in august 2023, avatr completed its series b financing round, achieving a valuation of nearly 20 billion rmb. changan automobile, china southern industrial asset management, and liangjiang industrial fund continued to increase their investments. additionally, it attracted state - owned capital from chongqing industrial investment fund, china everbright investment, and guangkai holdings. changan automobile remains the largest shareholder, with its ownership stake unchanged at 40. 99 %. catl is the second - largest shareholder, with its ownership stake decreasing from 17. 10 | https://en.wikipedia.org/wiki/Avatr_Technology |
the development of information and communication technologies suggests some spectacular changes in the methods used for teaching scientific subjects. nowadays, the development of software and hardware makes it possible to simulate processes as close to reality as we want. however, when we are trying to explain some complex physical processes, it is better to simplify the problem under study using simplified pictures of the total process by eliminating some elements that make it difficult to understand this process. in this work we focus our attention on the doppler effect which requires the space - time visualization that is very difficult to obtain using the traditional teaching resources. we have designed digital simulations as a complement of the theoretical explanation in order to help students understand this phenomenon. | arxiv:physics/0702036 |
we study the global dynamics of the collision of two solitons having the same mass for one - dimensional nonlinear schr \ " odinger models with multi - power nonlinearity. for any natural number k, it is verified that if the incoming speed v between the two solitary waves is small enough, then, after the collision, the two solitons will move away with an outcoming speed v _ { f } = v + o ( v ^ { k } ) and the remainder of the solution will also have energy and weighted norms of order o ( v ^ { k } ). this is applied to the one - dimensional models with polynomial odd nonlinearity having a stable soliton such as the cubic nls and the cubic - quintic nls. | arxiv:2403.12336 |
holomorphic manifolds over cayley - dickson algebras are defined and their embeddings and immersions are studied. | arxiv:1204.1545 |
a prime goal of quantum tomography is to provide quantitatively rigorous characterisation of quantum systems, be they states, processes or measurements, particularly for the purposes of trouble - shooting and benchmarking experiments in quantum information science. a range of techniques exist to enable the calculation of errors, such as monte - carlo simulations, but their quantitative value is arguably fundamentally flawed without an equally rigorous way of authenticating the quality of a reconstruction to ensure it provides a reasonable representation of the data, given the known noise sources. a key motivation for developing such a tool is to enable experimentalists to rigorously diagnose the presence of technical noise in their tomographic data. in this work, i explore the performance of the chi - squared goodness - of - fit test statistic as a measure of reconstruction quality. i show that its behaviour deviates noticeably from expectations for states lying near the boundaries of physical state space, severely undermining its usefulness as a quantitative tool precisely in the region which is of most interest in quantum information processing tasks. i suggest a simple, heuristic approach to compensate for these effects and present numerical simulations showing that this approach provides substantially improved performance. | arxiv:1212.2982 |
bessel beams carry orbital angular momentum ( oam ). opening up of the hilbert space of oam for information coding makes bessel beams potential candidates for utility in data transfer and optical communication. a laser bullet is the ultra - short and tightly - focused analogue of a non - diffracting and non - dispersing laser bessel beam. here, we show fully analytically that a bessel - bessel laser bullet possesses orbital angular momentum. analytic investigation of the energy, linear momentum, energy flux, and angular momentum, associated with the fields of a bessel - bessel bullet, in an under - dense plasma, is conducted. the expressions reported here will play a crucial role in preparing the laser bullets for practical applications, such as data transfer in optical communication, x - and gamma - ray generation from colliding bullets with counter - propagating electron bunches, particle trapping, tweezing and laser acceleration. | arxiv:1812.11493 |
we prove a no - go theorem for the construction of a galilean boost invariant and $ z \ neq2 $ anisotropic scale invariant field theory with a finite dimensional basis of fields. two point correlators in such theories, we show, grow unboundedly with spatial separation. correlators of theories with an infinite dimensional basis of fields, for example, labeled by a continuous parameter, do not necessarily exhibit this bad behavior. hence, such theories behave effectively as if in one extra dimension. embedding the symmetry algebra into the conformal algebra of one higher dimension also reveals the existence of an internal continuous parameter. consideration of isometries shows that the non - relativistic holographic picture assumes a canonical form, where the bulk gravitational theory lives in a space - time with one extra dimension. this can be contrasted with the original proposal by balasubramanian and mcgreevy, and by son, where the metric of a $ d + 2 $ dimensional space - time is proposed to be dual of a $ d $ dimensional field theory. we provide explicit examples of theories living at fixed point with anisotropic scaling exponent $ z = \ frac { 2 \ ell } { \ ell + 1 } \,, \ ell \ in \ mathbb { z } $ | arxiv:1803.03676 |
in this paper we use an ab - initio quantum transport approach to study the electron current flowing through lithiated sno anodes for potential applications in li - ion batteries. by investigating a set of lithiated structures with varying lithium concentrations, it is revealed that lixsno can be a good conductor, with values comparable to bulk $ \ beta $ - sn and li. a deeper insight into the current distribution indicates that electrons preferably follow specific trajectories, which offer superior conducting properties than others. these channels have been identified and it is shown here how they can enhance or deteriorate the current flow in lithiated anode materials. | arxiv:1804.09433 |
cryogenic qubit controllers ( qcs ) are the key to build large - scale superconducting quantum processors. however, developing scalable qcs is challenging because the cooling power of a dilution refrigerator is too small ( ~ 10 $ \ mu $ w at ~ 10 mk ) to operate conventional logic families, such as complementary metal - oxide - semiconductor logic and superconducting single - flux - quantum logic, near qubits. here we report on a scalable qc using an ultra - low - power superconductor logic family, namely adiabatic quantum - flux - parametron ( aqfp ) logic. the aqfp - based qc, referred to as the aqfp - multiplexed qc ( aqfp - mux qc ), produces multi - tone microwave signals for qubit control with an extremely small power dissipation of 81. 8 pw per qubit. furthermore, the aqfp - mux qc adopts microwave multiplexing to reduce the number of coaxial cables for operating the entire system. as a proof of concept, we demonstrate an aqfp - mux qc chip that produces microwave signals at two output ports through microwave multiplexing and demultiplexing. experimental results show an output power of approximately $ - $ 80 dbm and on / off ratio of ~ 40 db at each output port. basic mixing operation is also demonstrated by observing sideband signals. | arxiv:2310.06544 |
in this note we present a model that can produce a mass shift in a resonance due to interference between a scattering amplitude and that amplitude having rescattering through the resonance. | arxiv:nucl-th/0303068 |
ac noise in disordered conductors causes both dephasing of the electron wave functions and a dc current around a mesoscopic ring. we demonstrate that the dephasing rate tau _ { \ phi } ^ { - 1 } in long wires and the dc current, induced by the same noise and averaged over an ensemble of small rings are connected. the ensemble - averaged h / 2e flux harmonic < i > of the current and the dephasing rate caused by the same uniform in space high frequency ac field are related in a remarkably simple way : < i > tau _ { \ phi } = c e. here e is an electron charge, and the constant c depends on the dyson symmetry class. for a pure potential disorder the current < i > is diamagnetic c = - ( 4 / \ pi ) and in the presence of strong spin - orbit scattering it is paramagnetic c = ( 2 / \ pi ). the relationship seems to agree reasonably with experiments. this suggests that the two puzzles : anomalously large persistent current [ l. p. levy et al., phys. rev. lett., v. 64, 2074 ( 1990 ) ] and the low - temperature saturation of the dephasing [ p. mohanty et al., phys. rev. lett., v. 78, 3366 ( 1997 ) ] may have a common solution. | arxiv:cond-mat/9910144 |
we study the intrinsic shapes of a sample of over 400 quiescent galaxies in the cores of the virgo and fornax clusters with luminosities $ 10 ^ { 6 } \ leq l _ { g } / l _ { \ odot } \ leq 10 ^ { 8 } $. similar to satellites of the local group and centaurus a, these faint, low surface brightness cluster galaxies are best described as a family of thick ( $ c / a > 0. 5 $ ), oblate - triaxial spheroids. however, the large sample size allows us to show that the flattening of their stellar distributions depends both on luminosity and on the presence of a nuclear star cluster. nucleated satellites are thicker at all luminosities compared to their non - nucleated counterparts, and fainter galaxies are systematically thicker as well, regardless of nucleation. once nucleation is accounted for, we find no evidence that the environment the satellites live in plays a relevant role in setting their three - dimensional structure. we interpret both the presence of stellar nuclei and the associated thicker shapes as the result of preferential early and rapid formation, effectively making these faint nucleated galaxies the first generation of cluster satellites. | arxiv:1901.04509 |
we apply the method of eigenfamilies to construct new explicit complex - valued p - harmonic functions on the non - compact classical lie groups, equipped with their natural semi - riemannian metrics. we then employ this same approach to manufacture explicit complex - valued harmonic morphisms on these groups. | arxiv:2102.07547 |
we show that the hypothesis of analyticity in the uniqueness theory of vacuum, or electrovacuum, static black holes is not needed. more generally, we show that prehorizons covering a closed set cannot occur in well - behaved domains of outer communications. | arxiv:1004.0513 |
bang - jensen - gutin - li type conditions are the conditions for hamiltonicity of digraphs which impose degree restrictions on nonadjacent vertices which have a common in - neighbor or a common out - neighbor. they can be viewed as an extension of fan type conditions in undirected graphs, as well as generalization of locally ( in -, out - ) semicomplete digraphs. since their first appearance in 1996, various bang - jensen - gutin - li type conditions for hamitonicity have come forth. in this paper we establish a condition of bang - jensen - gutin - li type which implies not only a hamiltonian cycle but also a 3 - cycle and an ( n - 1 ) - cycle, with well - characterized exceptional graphs. we conjecture that this condition implies the existence of cycle of every length. | arxiv:2504.21628 |
there is currently a strong interest in compact accelerator - based neutron source ( cans ) as a possible new type of source for neutron scattering experiments. a workshop around the " neutron scattering instrumentation around cans " was organized in july 2017 between several european institutes. this report summarizes the main outcome of the discussions. the document is aiming at providing general guidelines for the instrumentation around cans. detailed technical discussions are or will be provided in specific publications. | arxiv:1809.02370 |
we express the d = 4, n = 2 black hole effective potential for cubic holomorphic f functions and generic dyonic charges in terms of d = 5 real special geometry data. the 4d critical points are computed from the 5d ones, and their relation is elucidated. for symmetric spaces, we identify the bps and non - bps classes of attractors and the respective entropies. these are related by simple formulae, interpolating between four and five dimensions, depending on the volume modulus and on the 4d magnetic ( or electric ) charges, and holding true also for generic field configurations and for non - symmetric cubic geometries. | arxiv:0707.0964 |
the spin behaviour of the neutron star in the newly discovered young be / x - ray long - period pulsar sxp 1062 is discussed. the star is observed to rotate with the period of 1062s, and spin - down at the rate ~ - 2. 6 \ times 10 ^ { - 12 } hz s ^ { - 1 }. i show that all of the conventional accretion scenarios encounter major difficulties explaining the rapid spin - down of the pulsar. these difficulties can be, however, avoided within the magnetic accretion scenario in which the neutron star is assumed to accrete from a magnetized wind. the spin - down rate of the pulsar can be explained within this scenario provided the surface magnetic field of the neutron star is b _ * ~ 4 \ times 10 ^ { 13 } g. i show that the age of the pulsar in this case lies in the rage ( 2 - 4 ) \ times 10 ^ 4 yr, which is consistent with observations. the spin evolution of the pulsar is briefly discussed. | arxiv:1205.5953 |
let $ n $ be a positive integer, and let $ d \ equiv0 $ or $ 1 \ mod { 4 } $ be a negative integer. we define the sets $ \ mathcal { cm } ( d, \, y _ 1 ( n ) ^ \ pm ) $ and $ \ mathcal { cm } ( d, \, y ( n ) ^ \ pm ) $ as subsets of the shimura varieties $ y _ 1 ( n ) ^ \ pm $ and $ y ( n ) ^ \ pm $, respectively, consisting of cm points of discriminant $ d $ that are primitive modulo $ n $. by using the theory of definite form class groups, we show that the inverse limits \ begin { equation * } \ varprojlim _ n \, \ mathcal { cm } ( d, \, y _ 1 ( n ) ^ \ pm ) \ quad \ textrm { and } \ quad \ varprojlim _ n \, \ mathcal { cm } ( d, \, y ( n ) ^ \ pm ) \ end { equation * } naturally inherit group structures isomorphic to $ \ mathrm { gal } ( k ^ \ mathrm { ab } / \ mathbb { q } ) $ and $ \ mathrm { gal } ( k ^ \ mathrm { ab } ( t ^ { 1 / \ infty } ) / \ mathbb { q } ( t ) ) $, respectively, where $ k = \ mathbb { q } ( \ sqrt { d } ) $ and $ t $ is a transcendental number. these results provide an explicit and geometric interpretation of class field theory in terms of inverse limits of cm points on the associated shimura varieties. | arxiv:2505.09163 |
grover ' s algorithm confers on quantum computers a quadratic advantage over classical computers for searching in an arbitrary data set, a scenario that describes bitcoin mining. it has previously been argued that the only side - effect of quantum mining would be an increased difficulty. in this work, we argue that a crucial argument in the analysis of bitcoin security breaks down when quantum mining is performed. classically, a bitcoin fork occurs rarely, i. e., when two miners find a block almost simultaneously, due to propagation time effects. the situation differs dramatically when quantum miners use grover ' s algorithm, which repeatedly applies a procedure called a grover iteration. the chances of finding a block grow quadratically with the number of grover iterations applied. crucially, a miner does not have to choose how many iterations to apply in advance. suppose alice receives bob ' s new block. to maximize her revenue, she should stop and measure her state immediately in the hopes that her block ( rather than bob ' s ) will become part of the longest chain. the strong correlation between the miners ' actions and the fact that they all measure their states at the same time may lead to more forks - - which is known to be a security risk for bitcoin. we propose a mechanism that, we conjecture, will prevent this form of quantum mining, thereby circumventing the high rate of forks. | arxiv:1804.08118 |
the target wake time ( twt ) feature, introduced in wi - fi 6, was primarily meant as an advanced power save mechanism. however, it has some interesting applications in scheduling and resource allocation. twt - based resource allocation can be used to improve the user experience for certain applications, e. g., voip, iot, video streaming, etc. in this work, we analyze the packet arrival pattern for streaming traffic and develop a synthetic video streaming traffic generator that mimics real - world streaming traffic. we propose a two - stage approach where we calculate the twt duty cycle in the first step. in the subsequent step, we determine the multiplication factor ( mf ), which jointly dictates the required twt schedule for the synthetic traffic model. initial testing shows that key qos metrics can be met for sustained performance of synthetic traffic upon enabling twt, even in the presence of peak background congestion in the network. | arxiv:2310.02590 |
systems for heating, ventilation and air - conditioning ( hvac ) of buildings are traditionally controlled by a rule - based approach. in order to reduce the energy consumption and the environmental impact of hvac systems more advanced control methods such as reinforcement learning are promising. reinforcement learning ( rl ) strategies offer a good alternative, as user feedback can be integrated more easily and presence can also be incorporated. moreover, multi - agent rl approaches scale well and can be generalized. in this paper, we propose a multi - agent rl framework based on existing work that learns reducing on one hand energy consumption by optimizing hvac control and on the other hand user feedback by occupants about uncomfortable room temperatures. second, we show how to reduce training time required for proper rl - agent - training by using parameter sharing between the multiple agents and apply different pretraining techniques. results show that our framework is capable of reducing the energy by around 6 % when controlling a complete building or 8 % for a single room zone. the occupants complaints are acceptable or even better compared to a rule - based baseline. additionally, our performance analysis show that the training time can be drastically reduced by using parameter sharing. | arxiv:2309.06940 |
hi observations have revealed in several shell galaxies the presence of gaseous shells slightly displaced from the stellar shells radially, in the outward direction. we propose a mechanism to form this gaseous shells, based on the well - known phase - wrapping process of the companion matter in a merger, with nearly radial orbits. the mechanism relies on the existence of a clumpy interstellar matter, and on dynamical friction experienced by the companion core. | arxiv:astro-ph/9908162 |
we present comparison of numerical simulations of propagation of mhd waves, excited by subphotospheric perturbations, in two different ( " deep " and " shallow " ) magnetostatic models of the sunspots. the " deep " sunspot model distorts both the shape of the wavefront and its amplitude stronger than the " shallow " model. for both sunspot models, the surface gravity waves ( f - mode ) are affected by the sunspots stronger than the acoustic p - modes. the wave amplitude inside the sunspot depends on the photospheric strength of the magnetic field and the distance of the source from the sunspot axis. for the source located at 9 mm from the center of the sunspot, the wave amplitude increases when the wavefront passes through the central part of the sunspot. for the source distance of 12 mm, the wave amplitude inside the sunspot is always smaller than outside. for the same source distance from the sunspot center but for the models with different strength of the magnetic field, the wave amplitude inside the sunspot increases with the strength of the magnetic field. the simulations show that unlike the case of the uniform inclined background magnetic field, the p - and f - mode waves are not spatially separated inside the sunspot where the magnetic field is strongly non - uniform. these properties have to be taken into account for interpretation of observations of mhd waves traveling through sunspot regions. | arxiv:1002.1117 |
there have been many efforts to correct systematic effects in astronomical light curves to improve the detection and characterization of planetary transits and astrophysical variability. algorithms like the trend filtering algorithm ( tfa ) use simultaneously - observed stars to remove systematic effects, and binning is used to reduce high - frequency random noise. we present tfaw, a wavelet - based modified version of tfa. tfaw aims to increase the periodic signal detection and to return a detrended and denoised signal without modifying its intrinsic characteristics. we modify tfa ' s frequency analysis step adding a stationary wavelet transform filter to perform an initial noise and outlier removal and increase the detection of variable signals. a wavelet filter is added to tfa ' s signal reconstruction to perform an adaptive characterization of the noise - and trend - free signal and the noise contribution at each iteration while preserving astrophysical signals. we carried out tests over simulated sinusoidal and transit - like signals to assess the effectiveness of the method and applied tfaw to real light curves from tfrm. we also studied tfaw ' s application to simulated multiperiodic signals, improving their characterization. tfaw improves the signal detection rate by increasing the signal detection efficiency ( sde ) up to a factor ~ 2. 5x for low snr light curves. for simulated transits, the transit detection rate improves by a factor ~ 2 - 5x in the low - snr regime compared to tfa. tfaw signal approximation performs up to a factor ~ 2x better than bin averaging for planetary transits. the standard deviations of simulated and real tfaw light curves are ~ 40x better than tfa. tfaw yields better mcmc posterior distributions and returns lower uncertainties, less biased transit parameters and narrower ( ~ 10x ) credibility intervals for simulated transits. we present a newly - discovered variable star from tfrm. | arxiv:1702.06547 |
this study investigates remote synchronization in scale - free networks of coupled nonlinear oscillators inspired by synchronization observed in the brain ' s cortical regions and power grid. we employ the master stability function ( msf ) approach to analyze network stability across various oscillator models. synchronization results are obtained for a star network using linearization techniques and extended to arbitrary networks with benchmark oscillators, verifying consistent behavior. stable synchronous solutions emerge as the floquet multiplier decreases and the msf becomes negative. additionally, we demonstrate remote synchronization in a star network, where peripheral oscillators communicate exclusively through a central hub, drawing parallels to neuronal synchronization in the brain. experimental validation is achieved through an electronic circuit testbed, supported by nonlinear ode modeling and ltspice simulation. future work will extend the investigation to arbitrary network topologies, further elucidating synchronization dynamics in complex systems. | arxiv:2411.09335 |
in contention resolution, multiple processors are trying to coordinate to send discrete messages through a shared channel with limited communication. if two processors send at the same time, the messages collide and are not transmitted successfully. queue - free backoff protocols are an important special case - for example, google drive and aws instruct their users to implement binary exponential backoff to handle busy periods. it is a long - standing conjecture of aldous ( ieee trans. inf. theory 1987 ) that no stable backoff protocols exist for any positive arrival rate of processors. this foundational question remains open ; instability is only known in general when the arrival rate of processors is at least 0. 42 ( goldberg et al. sicomp 2004 ). we prove aldous ' conjecture for all backoff protocols outside of a tightly - constrained special case using a new domination technique to get around the main difficulty, which is the strong dependencies between messages. | arxiv:2203.17144 |
let $ f $ be a continuous real function defined in a subset of the real line. the standard definition of continuity at a point $ x $ allow us to correlate any given epsilon with a ( possibly depending of $ x $ ) delta value. this pairing is known as the epsilon - - delta relation of $ f $. in this work, we demonstrate the existence of a privileged choice of delta in the sense that it is continuous, invertible, maximal and it is the solution of a simple functional equation. we also introduce an algorithm that can be used to numerically calculate this map in polylogarithm time, proving the computability of the epsilon - - delta relation. finally, some examples are analyzed in order to showcase the accuracy and effectiveness of these methods, even when the explicit formula for the aforementioned privileged function is unknown due to the lack of analytical tools for solving the functional equation. | arxiv:1710.04514 |
the idea that the universe is a program in a giant quantum computer is both fascinating and suffers from various problems. nonetheless, it can provide a unified picture of physics and this can be very useful for the problem of quantum gravity where such a unification is necessary. in previous work we proposed quantum graphity, a simple way to model a dynamical spacetime as a quantum computation. in this paper, we give an easily readable introduction to the idea of the universe as a quantum computation, the problem of quantum gravity, and the graphity models. | arxiv:1201.3398 |
the absorption and emission spectrum arising from the vibrational motion of a molecule is mostly in the infrared region. these fingerprint absorptions of polar bonds enable us to acquire bond - specific chemical information from specimens. however, the mode mismatch between the atomic - scale dimensions of the chemical bonds and the resonance wavelength limits the direct detection of tiny amounts of samples such as self - assembled monolayers or biological membranes. to overcome this limitation, surface - enhanced infrared absorption spectroscopy ( seira ) has been proposed to enhance infrared absorption directly via local field enhancement. here, we report on the perfect absorption of molecular vibration enabled by critical coupling in the metamaterials. our molecular metamaterial design consists of a thin polymer layer sandwiched between a structured metal layer on top and a continuous metal layer at the bottom that supports the gap plasmon mode. the measured and simulated infrared spectra of the molecular metamaterial show broad and narrow absorption bands corresponding to the metamaterial and molecular vibration modes. we show that by tuning the structure ' s molecular film thickness and periodicity, vibrational absorption can be enhanced to near unity. we also show that for a particular periodicity of the array, metamaterial resonance can be completely suppressed, and only molecular vibrational absorption is excited, giving rise to an extremely narrow absorption band. | arxiv:2411.08990 |
in two - time - scale stochastic approximation ( sa ), two iterates are updated at varying speeds using different step sizes, with each update influencing the other. previous studies on linear two - time - scale sa have shown that the convergence rates of the mean - square errors for these updates depend solely on their respective step sizes, a phenomenon termed decoupled convergence. however, achieving decoupled convergence in nonlinear sa remains less understood. our research investigates the potential for finite - time decoupled convergence in nonlinear two - time - scale sa. we demonstrate that, under a nested local linearity assumption, finite - time decoupled convergence rates can be achieved with suitable step size selection. to derive this result, we conduct a convergence analysis of the matrix cross term between the iterates and leverage fourth - order moment convergence rates to control the higher - order error terms induced by local linearity. additionally, a numerical example is provided to explore the possible necessity of local linearity for decoupled convergence. | arxiv:2401.03893 |
a linear programming ( lp ) based framework is presented for obtaining converses for finite blocklength lossy joint source - channel coding problems. the framework applies for any loss criterion, generalizes certain previously known converses, and also extends to multi - terminal settings. the finite blocklength problem is posed equivalently as a nonconvex optimization problem and using a lift - and - project - like method, a close but tractable lp relaxation of this problem is derived. lower bounds on the original problem are obtained by the construction of feasible points for the dual of the lp relaxation. a particular application of this approach leads to new converses which recover and improve on the converses of kostina and verdu for finite blocklength lossy joint source - channel coding and lossy source coding. for finite blocklength channel coding, the lp relaxation recovers the converse of polyanskiy, poor and verdu and leads to a new improvement on the converse of wolfowitz, showing thereby that our lp relaxation is asymptotically tight with increasing blocklengths for channel coding, lossless source coding and joint source - channel coding with the excess distortion probability as the loss criterion. using a duality based argument, a new converse is derived for finite blocklength joint source - channel coding for a class of source - channel pairs. employing this converse, the lp relaxation is also shown to be tight for all blocklengths for the minimization of the expected average symbol - wise hamming distortion of a $ q $ - ary uniform source over a $ q $ - ary symmetric memoryless channel for any $ q \ in n $. the optimization formulation and the lift - and - project method are extended to networked settings and demonstrated by obtaining an improvement on a converse of zhou et al. for the successive refinement problem for successively refinable source - distortion measure triplets. | arxiv:1608.03165 |
confinement phenomenology characteristic of magnetically confined plasmas emerges naturally from a simple sandpile algorithm when the parameter controlling redistribution scalelength is varied. close analogues are found for enhanced confinement, edge pedestals, and edge localised modes ( elms ), and for the qualitative correlations between them. these results suggest that tokamak observations of avalanching transport are deeply linked to the existence of enhanced confinement and elms. | arxiv:physics/0010032 |
a self - consistent system of interacting spinor and scalar fields is considered within the scope of bianchi type vi cosmological model filled with a perfect fluid. the contribution of the cosmological constant ( $ \ lambda $ - term ) is taken into account as well. exact self - consistent solutions to the field equations are obtained for a special choice of spatial inhomogeneity and the interaction terms of the spinor and scalar fields. it has been found that some special choice of metric functions can give rise to a singularity - free solutions independent of the value and sign of the $ \ lambda $ term. it is also shown that the introduction of a positive $ \ lambda $, the most widespread kind of dark energy, leads to the rapid growth of the universe, while the negative one, corresponding to an additional gravitational energy gives rise to an oscillatory or non - periodic mode of expansion. the role of the spatial inhomogeneity in the evolution of the universe is clarified within the scope of the considered models. | arxiv:gr-qc/0701059 |
this work provides a low - power method for chaos generation which is generally applicable to nonlinear m / nems resonators. the approach taken is independent of the material, scale, design, and actuation of the device in question ; it simply assumes a good quality factor and a duffing type nonlinearity, features that are commonplace to m / nems resonators. the approach models the rotating - frame dynamics to analytically constrain the parameter space required for chaos generation. by leveraging these common properties of m / nems devices, a period - doubling route to chaos is generated using an order - of - magnitude smaller forcing than typically reported in the literature. | arxiv:2005.09215 |
we study, within the fluctuation exchange approximation, the spin - fluctuation - mediated superconductivity in hubbard - type models possessing electron and hole bands, and compare them with a model on a square lattice with a large fermi surface. in the square lattice model, superconductivity is more enhanced for better nesting for a fixed band filling. by contrast, in the models with electron and hole bands, superconductivity is optimized when the fermi surface nesting is degraded to some extent, where finite energy spin fluctuation around the nesting vector develops. the difference lies in the robustness of the nesting vector, namely, in models with electron and hole bands, the wave vector at which the spin susceptibility is maximized is fixed even when the nesting is degraded, whereas when the fermi surface is large, the nesting vector varies with the deformation of the fermi surface. we also discuss the possibility of realizing in actual materials the bilayer hubbard model, which is a simple model with electron and hole bands, and is expected to have a very high t _ c. | arxiv:1705.00421 |
we consider the problem of testing whether two samples of contaminated data, possibly paired, are from the same distribution. is is assumed that the contaminations are additive noises with known moments of all orders. the test statistic is based on the polynomials moments of the difference between observations and noises.. a data driven selection is proposed to choose automatically the number of involved polynomials. we present a simulation study in order to investigate the power of the proposed test within discrete and continuous cases. a real - data example is presented to demonstrate the method. | arxiv:1105.1536 |
we acquired spectra of 24 lmc pne in the 1150 - - 3000 \ aa range in order to determine carbon and other ionic abundances. the sample more than doubles the number of lmc pne with good quality uv spectra in this wavelength range, and whose optical images are available in the { \ it hst } archive. the { \ it space telescope imaging spectrograph } was used with a very large aperture to obtain virtually slit - less spectra, thus the monochromatic images in the major nebulae emission lines are also available. the analysis of the data shows extremely good quality spectra. this paper presents the emission lines identified and measured, and the calculation of the ionic abundances of the emitting carbon and other ions, and total carbon abundance. p - cygni profiles have been found in a fraction of the nebulae, and the limiting velocities of the stellar winds estimated. the total carbon abundance can be inferred reliably in most nebulae. we found that the average carbon abundance in round and elliptical pne is one order of magnitude larger than that of the bipolar pne, while elliptical and round pne with a bipolar core have a bimodal behavior. this results confirm that bipolarity in lmc pne is tightly correlated with high mass progenitors. when compared to predicted yields, we found that the observed abundance ratio show a shift toward higher carbon abundances, that may be due to initial conditions assumed in the models not appropriate for lmc pne. | arxiv:astro-ph/0411631 |
our low - temperature magneto - raman scattering measurements performed on graphene - like locations on the surface of bulk graphite reveal a new series of magneto - phonon resonances involving both k - point and gamma - point phonons. in particular, we observe for the first time the resonant splitting of three crossing excitation branches. we give a detailed theoretical analysis of these new resonances. our results highlight the role of combined excitations and the importance of multi - phonon processes ( from both k and gamma points ) for the relaxation of hot carriers in graphene. | arxiv:1506.05700 |
we calculate the radiation spectra from advection - dominated accretion flows ( adafs ), taking into account the effects of a global magnetic field. calculation is based on the analytic model for magnetized adafs proposed by kaburaki, where a large - scale magnetic field controls the accretion process. adjusting a few parameters, we find that our model can well reproduce the observed spectrum of sagittarius a $ ^ { * } $. the result is discussed in comparison with those of well - known adaf models, where the turbulent viscosity controls the accretion process. | arxiv:astro-ph/0002010 |
we study synchronizing partial dfas, which extend the classical concept of synchronizing complete dfas and are a special case of synchronizing unambiguous nfas. a partial dfa is called synchronizing if it has a word ( called a \ emph { reset word } ) whose action brings a non - empty subset of states to a unique state and is undefined for all other states. the class of strongly connected partial automata is precisely the class of automata recognized prefix codes. while in the general case the problem of checking whether a partial dfa is synchronizing is pspace - complete, we show that in the strongly connected case this problem can be efficiently reduced to the same problem for a complete dfa. using combinatorial, algebraic, and formal languages methods, we develop techniques that relate main synchronization problems for strongly connected partial dfas to the same problems for complete dfas. in particular, this includes the \ v { c } ern \ ' { y } and the rank conjectures, the problem of finding a reset word, and upper bounds on the length of the shortest reset words of literal automata of finite prefix codes. we conclude that solving fundamental synchronization problems is equally hard in both models, as an essential improvement of the results for one model implies an improvement for the other. | arxiv:2101.05057 |
we construct a structure preserving non - conforming finite element approximation scheme for the bi - harmonic wave maps into spheres equation. it satisfies a discrete energy law and preserves the non - convex sphere constraint of the continuous problem. the discrete sphere constraint is enforced at the mesh - points via a discrete lagrange multiplier. this approach restricts the spatial approximation to the ( non - conforming ) linear finite elements. we show that the numerical approximation converges to the weak solution of the continuous problem in spatial dimension $ d = 1 $. the convergence analysis in dimensions $ d > 1 $ is complicated by the lack of a discrete product rule as well as the low regularity of the numerical approximation in the non - conforming setting. hence, we show convergence of the numerical approximation in higher - dimensions by introducing additional stabilization terms in the numerical approximation. we present numerical experiments to demonstrate the performance of the proposed numerical approximation and to illustrate the regularizing effect of the bi - laplacian which prevents the formation of singularities. | arxiv:2409.11366 |
fuglede - putnam theorem have been proved for a considerably large number of class of operators. in this paper by using the spectral theory, we obtain a theoretical and general framework from which fuglede - putnam theorem may be promptly established for many classes of operators. | arxiv:1603.07494 |
this paper is concerned with the minimum - time path - planning problem for a dubins airplane under the influence of steady wind. the path - planning problem, by transforming into the air - relative frame, is equivalent to finding the minimum - time control strategy for a dubins airplane to intercept a moving target. in the air - relative frame, by applying pontryagin ' s maximum principle, the candidates for the minimum - time solution are categorized into a family of four types : sc, cc, ccc, csc, where s denotes a straight line segment and c denotes a circular segment. furthermore, the geometric properties for each type are analyzed, indicating that the paths of sc and cc can be obtained by finding the roots of a quadratic equation, while the paths of ccc and csc are determined by the roots of some nonlinear transcendental equations. an improved bisection method is presented in the paper so that all the roots of the transcendental equations can be computed within a constant time. as a consequence, the globally optimal path can be obtained within a constant time by comparing all the candidates of the four types. finally, numerical examples are presented, showing that the closed - form solutions derived in the paper can ensure to find the globally optimal solution by comparing with existing methods in the literature. | arxiv:2412.04797 |
to act. bagozzi, davis and warshaw say : because new technologies such as personal computers are complex and an element of uncertainty exists in the minds of decision makers with respect to the successful adoption of them, people form attitudes and intentions toward trying to learn to use the new technology prior to initiating efforts directed at using. attitudes towards usage and intentions to use may be ill - formed or lacking in conviction or else may occur only after preliminary strivings to learn to use the technology evolve. thus, actual usage may not be a direct or immediate consequence of such attitudes and intentions. earlier research on the diffusion of innovations also suggested a prominent role for perceived ease of use. tornatzky and klein analysed the adoption, finding that compatibility, relative advantage, and complexity had the most significant relationships with adoption across a broad range of innovation types. eason studied perceived usefulness in terms of a fit between systems, tasks and job profiles, using the terms " task fit " to describe the metric. legris, ingham and collerette suggest that tam must be extended to include variables that account for change processes and that this could be achieved through adoption of the innovation model into tam. = = usage = = several researchers have replicated davis ' s original study to provide empirical evidence on the relationships that exist between usefulness, ease of use and system use. much attention has focused on testing the robustness and validity of the questionnaire instrument used by davis. adams et al. replicated the work of davis to demonstrate the validity and reliability of his instrument and his measurement scales. they also extended it to different settings and, using two different samples, they demonstrated the internal consistency and replication reliability of the two scales. hendrickson et al. found high reliability and good test - retest reliability. szajna found that the instrument had predictive validity for intent to use, self - reported usage and attitude toward use. the sum of this research has confirmed the validity of the davis instrument, and to support its use with different populations of users and different software choices. segars and grover re - examined adams et al. ' s ) replication of the davis work. they were critical of the measurement model used, and postulated a different model based on three constructs : usefulness, effectiveness, and ease - of - use. these findings do not yet seem to have been replicated. however, some aspects of these findings were tested and supported by workman by separating the dependent variable into information use versus technology use. mark keil and | https://en.wikipedia.org/wiki/Technology_acceptance_model |
using the slave - rotor mean - field theory, we study the formation of kondo resonance in graphene induced from vacancies. at the dirac neutrality point, we find acritical hybridization strength beyond which the kondo resonance takes place, despite vanishing density of states. we also find that the line - shapes of the kondo peak are entirely different from lorentzian shown in normal metallic hosts. the dependence of kondo temperature on the effective hybridization parameter of the spinon field turns out to be linear in contrast to the quadratic dependence in normal metals. upon doping we find strong electron - hole asymmetry for the dependence of kondo temperature on the chemical potential. | arxiv:1308.4173 |
talbot interferometer, as a periodic reproduction of momentum distribution in the time domain, finds significant applications in multiple research. the inter - particle interactions during the diffraction and interference process introduce numerous many - body physics problems, leading to unconventional interference characteristics. this work investigates both experimentally and theoretically the influence of interaction in a talbot interferometer with a $ ^ { 6 } \ rm li _ 2 $ molecular bose - einstein condensate in a one - dimensional optical lattice, with interaction strength directly tunable via magnetic feshbach resonance. a clear dependence of the period and amplitude of signal revivals on the interaction strength can be observed. while interactions increase the decay rate of the signal and advance the revivals, we find that over a wide range of interactions, the talbot interferometer remains highly effective over a certain evolutionary timescale, including the case of fractional talbot interference. this work provides insight into the interplay between interaction and the coherence properties of a temporal talbot interference in optical lattices, paving the way for research into quantum interference in strongly interacting systems. | arxiv:2402.14629 |
we study the emission spectrum of a qubit under deep strong driving in the high - frequency dispersive regime when the driving frequency and strength exceed significantly the qubit transition frequency. closed - form expressions for the steady - state first - order field correlation function and the multiphoton emission spectrum are obtained. the spectrum comprises a series of narrow delta - like lines that stem from coherent processes and lorenzian peaks that result from the incoherent scattering of photons. the oscillating dependence of the widths of the emission lines on the driving strength is predicted. we show how the features of this dependence are governed by the qubit dephasing and relaxation rates. | arxiv:1712.04758 |
recently, a conjecture due to hendry was disproved which stated that every hamiltonian chordal graph is cycle extendible. here we further explore the conjecture, showing that it fails to hold even when a number of extra conditions are imposed. in particular, we show that hendry ' s conjecture fails for strongly chordal graphs, graphs with high connectivity, and if we relax the definition of " cycle extendible " considerably. we also consider the original conjecture from a subtree intersection model point of view, showing that a result of abuieda et al is nearly best possible. | arxiv:2007.07464 |
in this paper, we develop approximate dynamic programming methods for stochastic systems modeled as markov decision processes, given both soft performance criteria and hard constraints in a class of probabilistic temporal logic called probabilistic computation tree logic ( pctl ). our approach consists of two steps : first, we show how to transform a class of pctl formulas into chance constraints that can be enforced during planning in stochastic systems. second, by integrating randomized optimization and entropy - regulated dynamic programming, we devise a novel trajectory sampling - based approximate value iteration method to iteratively solve for an upper bound on the value function while ensuring the constraints that pctl specifications are satisfied. particularly, we show that by the on - policy sampling of the trajectories, a tight bound can be achieved between the upper bound given by the approximation and the true value function. the correctness and efficiency of the method are demonstrated using robotic motion planning examples. | arxiv:1810.02199 |
we explore a key architectural aspect of deep convolutional neural networks : the pattern of internal skip connections used to aggregate outputs of earlier layers for consumption by deeper layers. such aggregation is critical to facilitate training of very deep networks in an end - to - end manner. this is a primary reason for the widespread adoption of residual networks, which aggregate outputs via cumulative summation. while subsequent works investigate alternative aggregation operations ( e. g. concatenation ), we focus on an orthogonal question : which outputs to aggregate at a particular point in the network. we propose a new internal connection structure which aggregates only a sparse set of previous outputs at any given depth. our experiments demonstrate this simple design change offers superior performance with fewer parameters and lower computational requirements. moreover, we show that sparse aggregation allows networks to scale more robustly to 1000 + layers, thereby opening future avenues for training long - running visual processes. | arxiv:1801.05895 |
in recent years, advances in high throughput sequencing technology have led to a need for specialized methods for the analysis of digital gene expression data. while gene expression data measured on a microarray take on continuous values and can be modeled using the normal distribution, rna sequencing data involve nonnegative counts and are more appropriately modeled using a discrete count distribution, such as the poisson or the negative binomial. consequently, analytic tools that assume a gaussian distribution ( such as classification methods based on linear discriminant analysis and clustering methods that use euclidean distance ) may not perform as well for sequencing data as methods that are based upon a more appropriate distribution. here, we propose new approaches for performing classification and clustering of observations on the basis of sequencing data. using a poisson log linear model, we develop an analog of diagonal linear discriminant analysis that is appropriate for sequencing data. we also propose an approach for clustering sequencing data using a new dissimilarity measure that is based upon the poisson model. we demonstrate the performances of these approaches in a simulation study, on three publicly available rna sequencing data sets, and on a publicly available chromatin immunoprecipitation sequencing data set. | arxiv:1202.6201 |
the mathematician leonhard euler ( 1707 - 1783 ) appears to have been a philosophical optimist having written : " since the fabric of universe is the most perfect and is the work of the most wise creator, nothing whatsoever take place in this universe in which some relation of maximum or minimum does not appear. wherefore, there is absolutely no doubt that every effect in universe can be explained as satisfactory from final causes themselves the aid of the method of maxima and minima, as can from the effective causes ". having in mind this kind of optimism, in the papers [ 1 - 16 ] we introduced and investigated the possibility to construct a predictive analytic theory of the elementary particle interaction based on the principle of minimum distance in the space of quantum states ( pmd - sqs ). so, choosing the partial transition amplitudes as the system variational variables and the distance in the space of the quantum states as a measure of the system effectiveness, we obtained the results [ 1 - 16 ]. these results proved that the principle of minimum distance in space of quantum states ( pmd - sqs ) can be chosen as variational principle by which we can find the analytic expressions of the partial transition amplitudes. in this paper we present a description of hadron - hadron scattering via principle of minimum distance pmd - sqs when the distance in space of states is minimized with two directional constraints. then by using the available experimental ( pion - nucleon and kaon - nucleon ) phase shifts we obtained not only consistent experimental tests of the pmd - sqs optimality, but also strong experimental evidences for new principles in hadronic physics such as : principle of nonextensivity conjugation via the riesz - thorin relation ( 1 / 2p + 1 / 2q = 1 ) and a new principle of limited uncertainty in nonextensive quantum physics. | arxiv:0710.0742 |
the prevalence of smartphone and consumer camera has led to more evidence in the form of digital images, which are mostly taken in uncontrolled and uncooperative environments. in these images, criminals likely hide or cover their faces while their hands are observable in some cases, creating a challenging use case for forensic investigation. many existing hand - based recognition methods perform well for hand images collected in controlled environments with user cooperation. however, their performance deteriorates significantly in uncontrolled and uncooperative environments. a recent work has exposed the potential of hand recognition in these environments. however, only the palmar regions were considered, and the recognition performance is still far from satisfactory. to improve the recognition accuracy, an algorithm integrating a multi - spatial transformer network ( mstn ) and multiple loss functions is proposed to fully utilize information in full hand images. mstn is firstly employed to localize the palms and fingers and estimate the alignment parameters. then, the aligned images are further fed into pretrained convolutional neural networks, where features are extracted. finally, a training scheme with multiple loss functions is used to train the network end - to - end. to demonstrate the effectiveness of the proposed algorithm, the trained model is evaluated on ntu - pi - v1 database and six benchmark databases from different domains. experimental results show that the proposed algorithm performs significantly better than the existing methods in these uncontrolled and uncooperative environments and has good generalization capabilities to samples from different domains. | arxiv:2311.05383 |
one major challenge of disentanglement learning with variational autoencoders is the trade - off between disentanglement and reconstruction fidelity. previous studies, which increase the information bottleneck during training, tend to lose the constraint of disentanglement, leading to the information diffusion problem. in this paper, we present a novel framework for disentangled representation learning, devae, which utilizes hierarchical latent spaces with decreasing information bottlenecks across these spaces. the key innovation of our approach lies in connecting the hierarchical latent spaces through disentanglement - invariant transformations, allowing the sharing of disentanglement properties among spaces while maintaining an acceptable level of reconstruction performance. we demonstrate the effectiveness of devae in achieving a balance between disentanglement and reconstruction through a series of experiments and ablation studies on dsprites and shapes3d datasets. code is available at https : / / github. com / erow / disentanglement _ lib / tree / pytorch # devae. | arxiv:2303.12959 |
the autocorrelation function provides an objective test for the existence of special scales in the hierarchical clustering of young stars. we apply this measure to single - star photometry for the brightest main sequence stars in the small magellanic cloud ( smc ), the large magellanic cloud ( lmc ), m33, and m31, using data from the magellanic clouds photometric survey and the massey local group survey. our primary result is the identification of a transition to a higher correlation dimension ( weaker clustering ) at one kpc in the lmc and m31, and at 300 pc in m33. we suggest that this transition marks the large - scale regime where disk geometry and dynamics set the scale for structure. on smaller scales, the correlation functions for each galaxy are scale - free over at least two orders of magnitude, with a projected correlation dimension varying from 1. 0 for m31 to 1. 8 for the smc. this variation is probably caused by a combination of differences in stellar ages and masses, physical environment, and extinction. | arxiv:0804.4607 |
the construction of the cotensor coalgebra for an " abelian monoidal " category $ \ m $ which is also cocomplete, complete and ab5, was performed in [ a. ardizzoni, c. menini and d. \ c { s } tefan, \ emph { cotensor coalgebras in monoidal categories }, comm. algebra, to appear ]. it was also proved that this coalgebra satisfies a meaningful universal property which resembles the classical one. here the lack of the coradical filtration for a coalgebra $ e $ in $ \ m $ is filled by considering a direct limit $ \ widetilde { d } $ of a filtration consisting of wedge products of a subcoalgebra $ d $ of $ e $. the main aim of this paper is to characterize hereditary coalgebras $ \ widetilde { d } $, where $ d $ is a coseparable coalgebra in $ \ m $, by means of a cotensor coalgebra : more precisely, we prove that, under suitable assumptions, $ \ widetilde { d } $ is hereditary if and only if it is formally smooth if and only if it is the cotensor coalgebra $ t ^ c _ { d } ( d \ w d / d ) $ if and only if it is a cotensor coalgebra $ t ^ c _ { d } ( n ) $, where $ n $ is a certain $ d $ - bicomodule in $ \ m $. because of our choice, even when we apply our results in the category of vector spaces, new results are obtained. | arxiv:math/0602016 |
an optical model of classical photons propagating through array of many beam splitters is developed to give a physical analogy of parrondo ' s game and parrondo - harmer - abbott game. we showed both the two games are reasonable game without so - called game paradox and they are essentially the same. we designed the games with long - term memory on loop lattice and history - entangled game. the strong correlation between nearest two rounds of game can make the combination of two losing game win, lose or oscillate between win and loss. the periodic potential in brownian ratchet is analogous to a long chain of beam splitters. the coupling between two neighboring potential wells is equivalent to two coupled beam splitters. this correspondence may help us to understand the anomalous motion of exceptional brownian particles moving in the opposite direction to the majority. we designed the capital wave for a game by introducing correlations into independent capitals instead of sub - games. playing entangled quantum states in many coupled classical games obey the same rules for manipulating quantum states in many body physics. | arxiv:1010.5183 |
we derive exact relations to all orders in the $ \ alpha ' $ expansion for the charges of a bound system of heterotic strings, solitonic 5 - branes and, optionally, a kaluza - klein monopole. the expressions, which differ from those of the zeroth - order supergravity approximation, coincide with the values obtained when only the corrections of quadratic order in curvature are included. our computation relies on the consistency of string theory as a quantum theory of gravity ; the relations follow from the matching of the wald entropy with the microscopic degeneracy. in the heterotic frame, the higher - curvature terms behave as delocalized sources that introduce a shift between near - horizon and asymptotic charges. on the other hand, when described in terms of lower - dimensional effective fields, the solution carries constant charges over space which coincide with those of the asymptotic heterotic fields. in addition, we describe why the gauss - bonnet term, which only captures a subset of the relevant corrections of quadratic order in curvature, in some cases succeeds to reproduce the correct value for the wald entropy, while fails in others. | arxiv:1906.12287 |
in recent years the number of cubesats ( u - class spacecrafts ) launched into space has increased exponentially marking the dawn of the nanosatellite technology. in general these satellites have a much smaller mass budget compared to conventional scientific satellites which limits shielding of scientific instruments against direct and indirect radiation in space. in this paper we present a simulation framework to quantify the signal in large field - of - view gamma - ray scintillation detectors of satellites induced by x - ray / gamma - ray transients, by taking into account the response of the detector. furthermore, we quantify the signal induced by x - ray and particle background sources at a low - earth orbit outside south atlantic anomaly and polar regions. finally, we calculate the signal - to - noise ratio taking into account different energy threshold levels. our simulation can be used to optimize material composition and predict detectability of various astrophysical sources by cubesats. we apply the developed simulation to a satellite belonging to a planned camelot cubesat constellation. this project mainly aims to detect short and long gamma - ray bursts ( grbs ) and as a secondary science objective, to detect soft gamma - ray repeaters ( sgrs ) and terrestrial gamma - ray flashes ( tgfs ). the simulation includes a detailed computer - aided design ( cad ) model of the satellite to take into account the interaction of particles with the material of the satellite as accurately as possible. results of our simulations predict that cubesats can complement the large space observatories in high - energy astrophysics for observations of grbs, sgrs and tgfs. for the detectors planned to be on board of the camelot cubesats the simulations show that detections with signal - to - noise ratio of at least 9 for median grb and sgr fluxes are achievable. | arxiv:2102.08104 |
einstein gravitation theory can be extended by preserving its geometrical nature but changing the relation between curvature and energy - momentum tensors. this change accounts for radiative corrections, replacing the newton gravitation constant by two running couplings which depend on scale and differ in the two sectors of traceless and traced tensors. the metric and curvature tensors in the field of the sun, which were obtained in previous papers within a linearized approximation, are then calculated without this restriction. modifications of gravitational effects on geodesics are then studied, allowing one to explore phenomenological consequences of extensions lying in the vicinity of general relativity. some of these extended theories are able to account for the pioneer anomaly while remaining compatible with tests involving the motion of planets. the ppn ansatz corresponds to peculiar extensions of general relativity which do not have the ability to meet this compatibility challenge. | arxiv:gr-qc/0510068 |
an equilibrium of a delay differential equation ( dde ) is absolutely stable, if it is locally asymptotically stable for all delays. we present criteria for absolute stability of ddes with discrete time - delays. in the case of a single delay, the absolute stability is shown to be equivalent to asymptotic stability for sufficiently large delays. similarly, for multiple delays, the absolute stability is equivalent to asymptotic stability for hierarchically large delays. additionally, we give necessary and sufficient conditions for a linear dde to be hyperbolic for all delays. the latter conditions are crucial for determining whether a system can have stabilizing or destabilizing bifurcations by varying time delays. | arxiv:2103.11670 |
a wide variety of dissipative state preparation schemes suffer from a basic time - entanglement tradeoff : the more entangled the steady state, the slower the relaxation to the steady state. here, we show how a minimal kind of adaptive dynamics can be used to completely circumvent this tradeoff, and allow the dissipative stabilization of maximally entangled states with a finite time - scale. our approach takes inspiration from simple fermionic stabilization schemes, which surprisingly are immune to entanglement - induced slowdown. we describe schemes for accelerated stabilization of many - body entangled qubit states ( including spin squeezed states ), both in the form of discretized floquet circuits, as well as continuous time dissipative dynamics. our ideas are compatible with a number of experimental platforms. | arxiv:2409.06012 |
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