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multi - view datasets are increasingly collected in many real - world applications, and we have seen better learning performance by existing multi - view learning methods than by conventional single - view learning methods applied to each view individually. but, most of these multi - view learning methods are built on the assumption that at each instance no view is missing and all data points from all views must be perfectly paired. hence they cannot handle unpaired data but ignore them completely from their learning process. however, unpaired data can be more abundant in reality than paired ones and simply ignoring all unpaired data incur tremendous waste in resources. in this paper, we focus on learning uncorrelated features by semi - paired subspace learning, motivated by many existing works that show great successes of learning uncorrelated features. specifically, we propose a generalized uncorrelated multi - view subspace learning framework, which can naturally integrate many proven learning criteria on the semi - paired data. to showcase the flexibility of the framework, we instantiate five new semi - paired models for both unsupervised and semi - supervised learning. we also design a successive alternating approximation ( saa ) method to solve the resulting optimization problem and the method can be combined with the powerful krylov subspace projection technique if needed. extensive experimental results on multi - view feature extraction and multi - modality classification show that our proposed models perform competitively to or better than the baselines. | arxiv:2011.11124 |
this paper is devoted to dimensional reductions via the norm resolvent convergence. we derive explicit bounds on the resolvent difference as well as spectral asymptotics. the efficiency of our abstract tool is demonstrated by its application on seemingly different pde problems from various areas of mathematical physics ; all are analysed in a unified manner now, known results are recovered and new ones established. | arxiv:1701.08819 |
we prove a uniqueness result for bv solutions of scalar conservation laws with discontinuous flux in several space dimensions. the proof is based on the notion of kinetic solution and on a careful analysis of the entropy dissipation along the discontinuities of the flux. | arxiv:1404.5837 |
patient - specific cranial implants are important and necessary in the surgery of cranial defect restoration. however, traditional methods of manual design of cranial implants are complicated and time - consuming. our purpose is to develop a novel software named easycrania to design the cranial implants conveniently and efficiently. the process can be divided into five steps, which are mirroring model, clipping surface, surface fitting, the generation of the initial implant and the generation of the final implant. the main concept of our method is to use the geometry information of the mirrored model as the base to generate the final implant. the comparative studies demonstrated that the easycrania can improve the efficiency of cranial implant design significantly. and, the intra - and inter - rater reliability of the software were stable, which were 87. 07 + / - 1. 6 % and 87. 73 + / - 1. 4 % respectively. | arxiv:1706.07649 |
in the interaction of high - power laser beams with solid density plasma there are a number of mechanisms that generate strong magnetic fields. such fields subsequently inhibit or redirect electron flows, but can themselves be advected by heat fluxes, resulting in complex interplay between thermal transport and magnetic fields. we show that for heating by multiple laser spots reconnection of magnetic field lines can occur, mediated by these heat fluxes, using a fully implicit 2d vlasov - fokker - planck code. under such conditions, the reconnection rate is dictated by heat flows rather than alfv \ ` enic flows. we find that this mechanism is only relevant in a high $ \ beta $ plasma. however, the hall parameter $ \ omega _ c \ tau _ { ei } $ can be large so that thermal transport is strongly modified by these magnetic fields, which can impact longer time scale temperature homogeneity and ion dynamics in the system. | arxiv:1507.03629 |
we present a spectroscopic analysis of a sample of 48 m dwarf stars ( $ 0. 2 m _ { \ odot } < m < 0. 6 m _ { \ odot } $ ) from the hyades open cluster using high - resolution h - band spectra from the sdss / apogee survey. our methodology adopts spectrum synthesis with lte marcs model atmospheres, along with the apogee dr17 line list, to determine effective temperatures, surface gravities, metallicities, and projected rotational velocities. the median metallicity obtained for the hyades m dwarfs is [ m / h ] = 0. 09 $ \ pm $ 0. 03 dex, indicating a small internal uncertainty and good agreement with optical results for hyades red - giants. overall, the median radii are larger than predicted by stellar models by 1. 6 $ \ pm $ 2. 3 \ % and 2. 4 $ \ pm $ 2. 3 \ %, relative to a mist and dartmouth isochrone, respectively. we emphasize, however, that these isochrones are different and the fractional radius inflation for the fully - and partially - convective regimes have distinct behaviors depending on the isochrone. using a mist isochrone there is no evidence of radius inflation for the fully convective stars, while for the partially convective m - dwarfs the radii are inflated by 2. 7 $ \ pm $ 2. 1 \ %, which is in agreement with predictions from models that include magnetic fields. for the partially - convective stars, rapid - rotators present on average higher inflation levels than slow - rotators. the comparison with spots isochrone models indicates that the derived m dwarf radii can be explained by accounting for stellar spots in the photosphere of the stars, with 76 \ % of the studied m dwarfs having up to 20 \ % spot coverage, and the most inflated stars with $ \ sim $ 20 - - 40 \ % spot coverage. | arxiv:2305.07065 |
we investigate the work dissipated during the irreversible unfolding of single molecules by mechanical force, using the simplest model necessary to represent experimental data. the model consists of two levels ( folded and unfolded states ) separated by an intermediate barrier. we compute the probability distribution for the dissipated work and give analytical expressions for the average and variance of the distribution. to first order, the amount of dissipated work is directly proportional to the rate of application of force ( the loading rate ), and to the relaxation time of the molecule. the model yields estimates for parameters that characterize the unfolding kinetics under force in agreement with those obtained in recent experimental results ( liphardt, j., et al. ( 2002 ) { \ em science }, { \ bf 296 } 1832 - 1835 ). we obtain a general equation for the minimum number of repeated experiments needed to obtain an equilibrium free energy, to within $ k _ bt $, from non - equilibrium experiments using the jarzynski formula. the number of irreversible experiments grows exponentially with the ratio of the average dissipated work, $ \ bar { \ wdis } $, to $ k _ bt $. } | arxiv:physics/0210063 |
we present the contributions from all types of one - loop corrections to the scattering amplitude for the pair production of polarized charginos or neutralinos from polarized electron - positron annihilation. the contributions are classified in terms of ` ` prototypes ' ' distinguished by the number of particles inside the loops and their spins. the results are quoted in terms of the veltman - passarino functions in terms of general couplings and internal masses. the results can therefore be applied to any supersymmetric extension of the standard model or indeed to any polarized fermion pair production process in electron - positron annihilation. | arxiv:hep-ph/0103309 |
capsule networks ( capsnets ) have been proposed as an alternative to convolutional neural networks ( cnns ). this paper showcases how capsnets are more capable than cnns for autonomous agent exploration of realistic scenarios. in real world navigation, rewards external to agents may be rare. in turn, reinforcement learning algorithms can struggle to form meaningful policy functions. this paper ' s approach capsules exploration module ( caps - em ) pairs a capsnets architecture with an advantage actor critic algorithm. other approaches for navigating sparse environments require intrinsic reward generators, such as the intrinsic curiosity module ( icm ) and augmented curiosity modules ( acm ). caps - em uses a more compact architecture without need for intrinsic rewards. tested using vizdoom, the caps - em uses 44 % and 83 % fewer trainable network parameters than the icm and depth - augmented curiosity module ( d - acm ), respectively, for 1141 % and 437 % average time improvement over the icm and d - acm, respectively, for converging to a policy function across " my way home " scenarios. | arxiv:2002.03181 |
robotic probes on the lunar surface in a program known as the commercial lunar payload services. as of march 2022, nasa has awarded contracts for robotic lunar probes to companies such as intuitive machines, firefly space systems, and astrobotic. on april 16, 2021, nasa announced they had selected the spacex lunar starship as its human landing system. the agency ' s space launch system rocket will launch four astronauts aboard the orion spacecraft for their multi - day journey to lunar orbit where they will transfer to spacex ' s starship for the final leg of their journey to the surface of the moon. in november 2021, it was announced that the goal of landing astronauts on the moon by 2024 had slipped to no earlier than 2027 due to numerous factors. artemis i launched on november 16, 2022, and returned to earth safely on december 11, 2022. as of april 2025, nasa plans to launch artemis ii in april 2026. and artemis iii in 2027. additional artemis missions, artemis iv, artemis v, and artemis vi are planned to launch between 2028 and 2031. nasa ' s next major space initiative is the construction of the lunar gateway, a small space station in lunar orbit. this space station will be designed primarily for non - continuous human habitation. the construction of the gateway is expected to begin in 2027 with the launch of the first two modules : the power and propulsion element ( ppe ) and the habitation and logistics outpost ( halo ). operations on the gateway will begin with the artemis iv mission, which plans to deliver a crew of four to the gateway in 2028. in 2017, nasa was directed by the congressional nasa transition authorization act of 2017 to get humans to mars - orbit ( or to the martian surface ) by the 2030s. = = = = commercial leo development ( 2021 – present ) = = = = the commercial low earth orbit destinations program is an initiative by nasa to support work on commercial space stations that the agency hopes to have in place by the end of the current decade to replace the " international space station ". the three selected companies are : blue origin ( et al. ) with their orbital reef station concept, nanoracks ( et al. ) with their starlab space station concept, and northrop grumman with a station concept based on the halo - module for the gateway station. = = = robotic exploration = = = nasa has conducted many uncrewed and robotic spaceflight programs throughout its history. more than 1, 000 uncre | https://en.wikipedia.org/wiki/NASA |
does every $ n $ - vertex cayley graph have an orthonormal eigenbasis all of whose coordinates are $ o ( 1 / \ sqrt { n } ) $? while the answer is yes for abelian groups, we show that it is no in general. on the other hand, we show that every $ n $ - vertex cayley graph ( and more generally, vertex - transitive graph ) has an orthonormal basis whose coordinates are all $ o ( \ sqrt { \ log n / n } ) $, and that this bound is nearly best possible. our investigation is motivated by a question of assaf naor, who proved that random abelian cayley graphs are small - set expanders, extending a classic result of alon - - roichman. his proof relies on the existence of a bounded eigenbasis for abelian cayley graphs, which we now know cannot hold for general groups. on the other hand, we navigate around this obstruction and extend naor ' s result to nonabelian groups. | arxiv:2005.04502 |
in the analysis of bibliometric networks, researchers often use mapping and clustering techniques in a combined fashion. typically, however, mapping and clustering techniques that are used together rely on very different ideas and assumptions. we propose a unified approach to mapping and clustering of bibliometric networks. we show that the vos mapping technique and a weighted and parameterized variant of modularity - based clustering can both be derived from the same underlying principle. we illustrate our proposed approach by producing a combined mapping and clustering of the most frequently cited publications that appeared in the field of information science in the period 1999 - 2008. | arxiv:1006.1032 |
let $ q _ { n } $ be $ n $ - anisotropic laplacian operator, which contains the ordinary laplacian operator, $ n $ - laplacian operator and anisotropic laplacian operator. in this paper, we firstly obtain the properties for $ q _ { n } $, which contain the weak maximal principle, the comparison principle and the mean value property. then a priori estimates and blow - up analysis for solutions of $ - q _ { n } u = ve ^ { u } $ in bounded domain in $ \ mathbb { r } ^ { n } $, $ n \ geq 2 $ are established. finally, the behavior of sole blow - up point is further considered. | arxiv:1404.6611 |
node - based programming languages are increasingly popular in media arts coding domains. these languages are designed to be accessible to users with limited coding experience, allowing them to achieve creative output without an extensive programming background. using llm - based code generation to further lower the barrier to creative output is an exciting opportunity. however, the best strategy for code generation for visual node - based programming languages is still an open question. in particular, such languages have multiple levels of representation in text, each of which may be used for code generation. in this work, we explore the performance of llm code generation in audio programming tasks in visual programming languages at multiple levels of representation. we explore code generation through metaprogramming code representations for these languages ( i. e., coding the language using a different high - level text - based programming language ), as well as through direct node generation with json. we evaluate code generated in this way for two visual languages for audio programming on a benchmark set of coding problems. we measure both correctness and complexity of the generated code. we find that metaprogramming results in more semantically correct generated code, given that the code is well - formed ( i. e., is syntactically correct and runs ). we also find that prompting for richer metaprogramming using randomness and loops led to more complex code. | arxiv:2409.00856 |
different theorem provers tend to produce proof objects in different formats and this is especially the case for modal logics, where several deductive formalisms ( and provers based on them ) have been presented. this work falls within the general project of establishing a common specification language in order to certify proofs given in a wide range of deductive formalisms. in particular, by using a translation from the modal language into a first - order polarized language and a checker whose small kernel is based on a classical focused sequent calculus, we are able to certify modal proofs given in labeled sequent calculi, prefixed tableaux and free - variable prefixed tableaux. we describe the general method for the logic k, present its implementation in a prolog - like language, provide some examples and discuss how to extend the approach to other normal modal logics | arxiv:1609.04100 |
this technical report presents a bibliometric analysis of the top 30 cited researchers from usa, uk and china. the analysis is based on google scholar data using cids. the researchers were identified using their email suffix : edu, uk and cn. this na \ " { i } ve approach was able to produce rankings consistent with the scimago country rankings using mininal resources in a fully automated way. | arxiv:1310.5597 |
we consider the representations of hopf algebras involved in some physical models, namely, factorizable s - matrix models ( fsm ' s ), one - dimensional quantum spin chains ( qsc ' s ) and statistical vertex models ( svm ' s ). these physical representations have definite hermiticity assignments and lead to star structures on the corresponding hopf algebras. it turns out that for fsm ' s and the quantum mechanical time - evolution of qsc ' s the corresponding stars are compatible with the hopf structures. however, in the case of statistical models the resulting star structure is not a hopf one but what we call a twisted star. real representations of a twisted star hopf algebra do not close under the usual tensor product of representations. we briefly comment on the relation of these results with the wick rotation. | arxiv:math-ph/0003042 |
cosmic rays ( crs ) are dynamically important for the formation and evolution of galaxies by regulating star formation and by powering galactic outflows. however, to what extent crs regulate galaxy formation depends on the coupling strength of crs with the ambient plasma and the effective cr transport speed along the magnetic field. moreover, both properties sensitively depend on the cr momentum, which is largely unexplored in three - dimensional hydrodynamical simulations. we perform magneto - hydrodynamical simulations of entire galaxies with masses ranging from $ 10 ^ { 10 } $ to $ 10 ^ { 12 } \, \ mathrm { m } _ \ odot $ and compare dynamically coupled crs in the grey approximation with a spectrally resolved model that includes cr momenta from $ 0. 1 \, \ mathrm { gev } ~ c ^ { - 1 } $ to $ 100 \, \ mathrm { tev } ~ c ^ { - 1 } $. we find that hadronic cooling of crs dominates over alfv \ ' { e } n cooling, with the latter emulating cr losses as a result of streaming of crs down their pressure gradient. while star formation rates and galaxy morphologies are only mildly affected by the spectral cr modelling, mass loading factors of galactic outflows can differ by up to a factor of four in dwarf galaxies. all simulated low - mass halos ( $ m = 10 ^ { 10 } $, $ 10 ^ { 11 } $, and $ 3 \ times10 ^ { 11 } \, \ mathrm { m } _ \ odot $ ) drive strong outflows, where cr transport is temporally dominated by advection. in contrast, the milky way - mass galaxy with $ m = 10 ^ { 12 } \, \ mathrm { m } _ \ odot $ does not drive sustained outflows, so that cr transport is entirely dominated by diffusion. the effective energy weighted diffusion coefficients vary by two orders of magnitude from the canonical energy - weighted values of $ \ langle { d } \ rangle _ { e _ \ mathrm { cr } } \ sim10 ^ { 28 } \, \ mathrm { cm ^ 2 \, s ^ { - 1 } } $ in the disc up to $ 3 \ times10 ^ { 29 } \, \ mathrm { cm ^ 2 \, s ^ { - 1 } } $ in the circumgalactic medium, where we observe | arxiv:2303.03417 |
in this paper we study the effects of $ s \ to d + 2 { gluon } $ on $ k _ l \ to \ gamma \ gamma $ in the standard model. we find that this interaction can induce new sizeable su ( 3 ) and u ( 3 ) nonet breaking effects in $ k _ l - \ eta, \ eta ' $ transitions and therefore in $ k _ l \ to \ gamma \ gamma $ due to large matrix elements of $ < \ eta ( \ eta ' ) | \ alpha _ s g ^ a _ { \ mu \ nu } \ tilde g _ a ^ { \ mu \ nu } | 0 > $ from qcd anomaly. these new effects play an important role in explaining the observed value. we also study the effects of this interaction on the contribution to $ \ delta m _ { k _ l - k _ s } $. | arxiv:hep-ph/0210435 |
in this work we develop and analyze a mathematical model of biological control to prevent or attenuate the explosive increase of an invasive species population in a three - species food chain. we allow for finite time blow - up in the model as a mathematical construct to mimic the explosive increase in population, enabling the species to reach " disastrous " levels, in a finite time. we next propose various controls to drive down the invasive population growth and, in certain cases, eliminate blow - up. the controls avoid chemical treatments and / or natural enemy introduction, thus eliminating various non - target effects associated with such classical methods. we refer to these new controls as " ecological damping ", as their inclusion dampens the invasive species population growth. further, we improve prior results on the regularity and turing instability of the three - species model that were derived in earlier work. lastly, we confirm the existence of spatio - temporal chaos. | arxiv:1502.02010 |
the popularity of deep learning methods in the time series domain boosts interest in interpretability studies, including counterfactual ( cf ) methods. cf methods identify minimal changes in instances to alter the model predictions. despite extensive research, no existing work benchmarks cf methods in the time series domain. additionally, the results reported in the literature are inconclusive due to the limited number of datasets and inadequate metrics. in this work, we redesign quantitative metrics to accurately capture desirable characteristics in cfs. we specifically redesign the metrics for sparsity and plausibility and introduce a new metric for consistency. combined with validity, generation time, and proximity, we form a comprehensive metric set. we systematically benchmark 6 different cf methods on 20 univariate datasets and 10 multivariate datasets with 3 different classifiers. results indicate that the performance of cf methods varies across metrics and among different models. finally, we provide case studies and a guideline for practical usage. | arxiv:2408.12666 |
the role of $ \ ell _ { 1 } $ - norm in quantum mechanics ( qm ) has been studied through wigner ' s d - functions where $ \ ell _ { 1 } $ - norm means $ \ sum _ { i } \ left | c _ { i } \ right | $ for $ \ left | \ psi \ right \ rangle = \ sum _ { i } c _ { i } \ left | \ psi _ { i } \ right \ rangle $ if $ \ left | \ psi _ { i } \ right \ rangle $ are uni - orthogonal and normalized basis. it was shown that the present two types of transformation matrix acting on the natural basis in physics consist in an unified braiding matrix, which can be viewed as a particular solution of the yang - baxter equation ( ybe ). the maximum of the $ \ ell _ { 1 } $ - norm is connected with the maximally entangled states and topological quantum field theory ( tqft ) with two - component anyons while the minimum leads to the permutation for fermions or bosons. | arxiv:1001.3465 |
we demonstrate the role of selectivity variation in the structure of the non - equilibrium extended space - charge using 1d analytic and 2d numerical poisson - nernst - planck models for the electro - diffusive transport of a symmetric electrolyte. this provides a deeper understanding of the underly - ing mechanism behind a previously - observed maximum in the resistance - voltage curve for a shallow micro - nanochannel interface device [ schiffbauer, liel, leibowitz, park, and yossifon, submitted to phys. rev. e. ]. the current study helps to establish a connection between parameters such as the geometry and nanochannel surface - charge and the control of selectivity and resistance in the over - limiting current regime. | arxiv:1503.07117 |
in recent years, several efforts have been aimed at improving the robustness of vision models to domains and environments unseen during training. an important practical problem pertains to models deployed in a new geography that is under - represented in the training dataset, posing a direct challenge to fair and inclusive computer vision. in this paper, we study the problem of geographic robustness and make three main contributions. first, we introduce a large - scale dataset geonet for geographic adaptation containing benchmarks across diverse tasks like scene recognition ( geoplaces ), image classification ( geoimnet ) and universal adaptation ( geounida ). second, we investigate the nature of distribution shifts typical to the problem of geographic adaptation and hypothesize that the major source of domain shifts arise from significant variations in scene context ( context shift ), object design ( design shift ) and label distribution ( prior shift ) across geographies. third, we conduct an extensive evaluation of several state - of - the - art unsupervised domain adaptation algorithms and architectures on geonet, showing that they do not suffice for geographical adaptation, and that large - scale pre - training using large vision models also does not lead to geographic robustness. our dataset is publicly available at https : / / tarun005. github. io / geonet. | arxiv:2303.15443 |
cu $ _ 3 $ sbse $ _ 4 $ is a promising thermoelectric material due to high thermopower ( $ > 400 \ \ mu $ v / k ) at 300k and higher. although it has a simple crystal structure derived from zinc blende structure, previous work has shown that the physics of band gap formation is quite subtle due to the importance of active lone pair ( 5 $ s ^ 2 $ ) of sb and the non - local exchange interaction between these and se 5 $ p $ electrons. since for any application of semiconductors understanding the properties of defects is essential, we discuss the results of a systematic study of several point defects in cu $ _ 3 $ sbse $ _ 4 $ including vacancies and substitutions for each of the components. first principles calculations using density functional theory show that among variety of possible dopants, $ p $ - type doping can be done by substituting sb with group $ iv $ elements including sn, ge, pb and ti and $ n $ - type doping can be done by replacing cu by mg, zn. doping at the se site appears to be rather difficult. electronic structure calculations also suggest that the $ p $ - type behavior seen in nominally pure cu $ _ 3 $ sbse $ _ 4 $ is most likely due to cu vacancy rather than se vacancy. | arxiv:1409.4496 |
we study the effects of clouds on the dynamical and chemical evolution of gas - rich dwarf galaxies, in particular focusing on two model galaxies similar to izw18 and ngc1569. we consider both scenarios, clouds put at the beginning of the simulation and continuously created infalling ones. due to dynamical processes and thermal evaporation, the clouds survive only a few tens of myr, but during this time they act as an additional cooling agent and the internal energy of cloudy models is typically reduced by 20 - 40 % in comparison with models without clouds. the clouds delay the development of large - scale outflows, therefore helping to retain a larger amount of gas inside the galaxy. however, especially in models with continuous creation of infalling clouds, their bullet effect can pierce the expanding supershell and create holes through which the superbubble can vent freshly produced metals. moreover, assuming a pristine chemical composition for the clouds, their interaction with the superbubble dilutes the gas, reducing the metallicity ( by up to ~ 0. 4 dex ) with respect to the one attained by diffuse models. | arxiv:0908.1478 |
in this paper, we investigate the regularized mean curvature flow starting from an invariant hypersurface in a hilbert space equipped with an isometric and almost free action of a hilbert lie group whose orbits are regularized minimal. we prove that, if the invariant hypersurface satisfies a certain kind of horizontally convexity condition, then it collapses to an orbit of the hilbert lie group action along the regularized mean curvature flow. | arxiv:1607.02899 |
in this paper, we propose a way to achieve protected universal computation in a neutral atom quantum computer subject to collective dephasing. our proposal relies on the existence of a decoherence free subspace ( dfs ), resulting from symmetry properties of the errors. after briefly describing the physical system and the error model considered, we show how to encode information into the dfs and build a complete set of safe universal gates. finally, we provide numerical simulations for the fidelity of the different gates in the presence of time - dependent phase errors and discuss their performance and practical feasibility. | arxiv:quant-ph/0611246 |
we present here some known and some new examples of non - simple nsop1 theories andsome behaviour that kim - forking can exhibit in these theories, in particular that kim - forking afterforcing base monotonicity can or can not satisfy extension ( on arbitrary sets ). this study is based onthe results of chernikov, ramsey, dobrowolski and granger. | arxiv:2304.05404 |
metal - insulator transitions driven by magnetic fields have been extensively studied in 2d, but a 3d theory is still lacking. motivated by recent experiments, we develop a scaling theory for the metal - insulator transitions in the strong - magnetic - field quantum limit of a 3d system. by using a renormalization - group calculation to treat electron - electron interactions, electron - phonon interactions, and disorder on the same footing, we obtain the critical exponent that characterizes the scaling relations of the resistivity to temperature and magnetic field. by comparing the critical exponent with those in a recent experiment [ f. tang et al., nature ( london ) 569, 537 ( 2019 ) ], we conclude that the insulating ground state was not only a charge - density wave driven by electron - phonon interactions but also coexisting with strong electron - electron interactions and backscattering disorder. we also propose a current - scaling experiment for further verification. our theory will be helpful for exploring the emergent territory of 3d metal - insulator transitions under strong magnetic fields. | arxiv:2012.12541 |
we consider the convex hull of a finite sample of i. i. d. points uniformly distributed in a convex body in $ \ r ^ d $, $ d \ geq 2 $. we prove an exponential deviation inequality, which leads to rate optimal upper bounds on all the moments of the missing volume of the convex hull, uniformly over all convex bodies of $ \ r ^ d $, with no restriction on their volume, location in the space and smoothness of the boundary. | arxiv:1311.2902 |
for a positive integer $ d $, let $ p _ d ( n ) : = 0 ^ d + 1 ^ d + 2 ^ d + \ cdots + n ^ d $ ; i. e., $ p _ d ( n ) $ is the sum of the first $ d ^ { \ mathrm { th } } $ - powers up to $ n $. it ' s well known that $ p _ d ( n ) $ is a polynomial of degree $ d + 1 $ in $ n $. while this is usually proved by induction, once $ d $ is not small it ' s a challenge as one needs to know the polynomial for the inductive step. we show how this difficulty can be bypassed by giving a simple proof that $ p _ d ( n ) $ is a polynomial of degree $ d + 1 $ in $ n $ by using l ' hopital ' s rule, and show how we can then determine the coefficients by cramer ' s rule. this illustrates a general principle and the point of our paper : there ' s more than one path to a goal, different approaches have their advantages and disadvantages, and the more techniques one knows, the more likely one can successfully attack a problem. | arxiv:2302.03624 |
long - range time series forecasting is usually based on one of two existing forecasting strategies : direct forecasting and iterative forecasting, where the former provides low bias, high variance forecasts and the later leads to low variance, high bias forecasts. in this paper, we propose a new forecasting strategy called generative forecasting ( genf ), which generates synthetic data for the next few time steps and then makes long - range forecasts based on generated and observed data. we theoretically prove that genf is able to better balance the forecasting variance and bias, leading to a much smaller forecasting error. we implement genf via three components : ( i ) a novel conditional wasserstein generative adversarial network ( gan ) based generator for synthetic time series data generation, called cwgan - ts. ( ii ) a transformer based predictor, which makes long - range predictions using both generated and observed data. ( iii ) an information theoretic clustering algorithm to improve the training of both the cwgan - ts and the transformer based predictor. the experimental results on five public datasets demonstrate that genf significantly outperforms a diverse range of state - of - the - art benchmarks and classical approaches. specifically, we find a 5 % - 11 % improvement in predictive performance ( mean absolute error ) while having a 15 % - 50 % reduction in parameters compared to the benchmarks. lastly, we conduct an ablation study to demonstrate the effectiveness of the components comprising genf. | arxiv:2110.08770 |
we show that the daily average air humidity fluctuations exhibit non - trivial $ 1 / f ^ { \ alpha } $ behaviour which different from the spectral properties of other meteorological quantities. this feature and the fractal spatial strucure found in clouds make it plausible to regard air humidity fluctuations as a manifestation of self - organized criticality. we give arguments why the dynamics in air humidity can be similar to those in sandpile models of soc. | arxiv:adap-org/9311004 |
transducer - based models, such as rnn - transducer and transformer - transducer, have achieved great success in speech recognition. a typical transducer model decodes the output sequence conditioned on the current acoustic state and previously predicted tokens step by step. statistically, the number of blank tokens in the prediction results accounts for nearly 90 \ % of all tokens. it takes a lot of computation and time to predict the blank tokens, but only the non - blank tokens will appear in the final output sequence. therefore, we propose a method named fast - skip regularization, which tries to align the blank position predicted by a transducer with that predicted by a ctc model. during the inference, the transducer model can predict the blank tokens in advance by a simple ctc project layer without many complicated forward calculations of the transducer decoder and then skip them, which will reduce the computation and improve the inference speed greatly. all experiments are conducted on a public chinese mandarin dataset aishell - 1. the results show that the fast - skip regularization can indeed help the transducer model learn the blank position alignments. besides, the inference with fast - skip can be speeded up nearly 4 times with only a little performance degradation. | arxiv:2104.02882 |
the standard protocol for teleportation of a quantum state requires an entangled pair of particles and the use of two classical bits of information. here, we present two protocols for teleportation that require only one classical bit. in the first protocol, chained xor operations are performed on the particles before one of them is removed to the remote location where the state is being teleported. in the second protocol, three entangled particles are used. | arxiv:quant-ph/0305085 |
intuitively speaking, a classical field theory is background - independent if the structure required to make sense of its equations is itself subject to dynamical evolution, rather than being imposed ab initio. the aim of this paper is to provide an explication of this intuitive notion. background - independence is not a not formal property of theories : the question whether a theory is background - independent depends upon how the theory is interpreted. under the approach proposed here, a theory is fully background - independent relative to an interpretation if each physical possibility corresponds to a distinct spacetime geometry ; and it falls short of full background - independence to the extent that this condition fails. | arxiv:1106.0920 |
we show that the classical equations of motion for a particle on three dimensional fuzzy space and on the fuzzy sphere are underpinned by a natural lorentz geometry. from this geometric perspective, the equations of motion generally correspond to forced geodesic motion, but for an appropriate choice of noncommutative dynamics, the force is purely noncommutative in origin and the underpinning lorentz geometry some standard space - time with, in general, non - commutatuve corrections to the metric. for these choices of the noncommutative dynamics the commutative limit therefore corresponds to geodesic motion on this standard space - time. we identify these lorentz geometries to be a minkowski metric on $ \ mathbb { r } ^ 4 $ and $ \ mathbb { r } \ times s ^ 2 $ in the cases of a free particle on three dimensional fuzzy space ( $ \ mathbb { r } ^ 3 _ \ star $ ) and the fuzzy sphere ( $ s ^ 2 _ \ star $ ), respectively. we also demonstrate the equivalence of the on - shell dynamics of $ s ^ 2 _ \ star $ and a relativistic charged particle on the commutative sphere coupled to the background magnetic field of a dirac monopole. | arxiv:1905.05018 |
i review the status of lattice - qcd calculations relevant to quark flavor physics. the recent availability of physical - mass ensembles with large physical volumes generated by a growing number of lattice collaborations is an exciting development and i discuss their impact on the landscape of lattice flavor physics calculations. the activities of the newly formed flag - 2 collaboration which provides averages of quantities calculated in lattice qcd that are relevant for quark flavor physics are also discussed. my talk covers ( a subset of ) the same quantities reviewed by flag - 2, including results for $ k $, $ d _ { ( s ) } $, and $ b _ { ( s ) } $ meson decay constants and semileptonic decay form factors, as well as for hadronic matrix elements of neutral ( $ k $, $ d $, and $ b _ { ( s ) } $ ) meson mixing. i also briefly discuss recent progress towards understanding nonleptonic $ k $ decay and long - distance contributions to $ \ delta m _ k $. | arxiv:1403.5252 |
for a two - dimensional schr \ " odinger operator $ h _ { \ alpha v } = - \ delta - \ alpha v $ with the radial potential $ v ( x ) = f ( | x | ), f ( r ) \ ge 0 $, we study the behavior of the number $ n _ - ( h _ { \ alpha v } ) $ of its negative eigenvalues, as the coupling parameter $ \ alpha $ tends to infinity. we obtain the necessary and sufficient conditions for the semi - classical growth $ n _ - ( h _ { \ alpha v } ) = o ( \ alpha ) $ and for the validity of the weyl asymptotic law. | arxiv:1108.1002 |
this paper describes adaptations for eafi, a parser for easy - first parsing of discontinuous constituents, to adapt it to multiple languages as well as make use of the unlabeled data that was provided as part of the spmrl shared task 2014. | arxiv:1409.3813 |
photometry and spectroscopy of the unique pre - main sequence eclipsing object kh15d in the young cluster ngc 2264 are presented. the orbital period is 48. 34 days and both the length ( ~ 16 d ) and depth ( ~ 3 mag ) of the eclipse have increased with time. a brightening near the time of central eclipse is confirmed in the recent data but at a much smaller amplitude than was originally seen. spectra taken when the star is bright show that the primary is a weak t tauri star of spectral type k7. during eclipse there is no detectable change in spectral type or reddening, indicating that the obscuration is caused by rather large dust grains and / or macroscopic objects. evidently the star is eclipsed by an extended feature in its circumstellar disk orbiting with a semi - major axis of ~ 0. 2 au. continued photometric monitoring should allow us to probe the disk structure with a spatial resolution of ~ 3 x 10 ^ 6 km or better. | arxiv:astro-ph/0105412 |
importance sampling has become an indispensable strategy to speed up optimization algorithms for large - scale applications. improved adaptive variants - using importance values defined by the complete gradient information which changes during optimization - enjoy favorable theoretical properties, but are typically computationally infeasible. in this paper we propose an efficient approximation of gradient - based sampling, which is based on safe bounds on the gradient. the proposed sampling distribution is ( i ) provably the best sampling with respect to the given bounds, ( ii ) always better than uniform sampling and fixed importance sampling and ( iii ) can efficiently be computed - in many applications at negligible extra cost. the proposed sampling scheme is generic and can easily be integrated into existing algorithms. in particular, we show that coordinate - descent ( cd ) and stochastic gradient descent ( sgd ) can enjoy significant a speed - up under the novel scheme. the proven efficiency of the proposed sampling is verified by extensive numerical testing. | arxiv:1711.02637 |
deep metric learning aims to transform input data into an embedding space, where similar samples are close while dissimilar samples are far apart from each other. in practice, samples of new categories arrive incrementally, which requires the periodical augmentation of the learned model. the fine - tuning on the new categories usually leads to poor performance on the old, which is known as " catastrophic forgetting ". existing solutions either retrain the model from scratch or require the replay of old samples during the training. in this paper, a complete online deep metric learning framework is proposed based on mutual distillation for both one - task and multi - task scenarios. different from the teacher - student framework, the proposed approach treats the old and new learning tasks with equal importance. no preference over the old or new knowledge is caused. in addition, a novel virtual feature estimation approach is proposed to recover the features assumed to be extracted by the old models. it allows the distillation between the new and the old models without the replay of old training samples or the holding of old models during the training. a comprehensive study shows the superior performance of our approach with the support of different backbones. | arxiv:2203.05201 |
we present a general information theoretic approach for identifying functional subgraphs in complex networks where the dynamics of each node are observable. we show that the uncertainty in the state of each node can be expressed as a sum of information quantities involving a growing number of correlated variables at other nodes. we demonstrate that each term in this sum is generated by successively conditioning mutual informations on new measured variables, in a way analogous to a discrete differential calculus. the analogy to a taylor series suggests efficient search algorithms for determining the state of a target variable in terms of functional groups of other degrees of freedom. we apply this methodology to electrophysiological recordings of networks of cortical neurons grown it in vitro. despite strong stochasticity, we show that each cell ' s patterns of firing are generally explained by the activity of a small number of other neurons. we identify these neuronal subgraphs in terms of their mutually redundant or synergetic character and reconstruct neuronal circuits that account for the state of each target cell. | arxiv:0712.2218 |
in the tapping mode, a variation of the oscillation amplitude and phase as a function of the tip sample distance is the necessary measurement to access quantitatively to the properties of the surface. in the present work, we give a systematic comparison between experimental data recorded on two surfaces, phase and amplitude, and theoretical curves. with an interaction between the tip and the surface taking into account an attractive and a repulsive term, the analytical approach is unable to properly describe the relationship between the phase variation and the oscillation amplitude variation. when an additional dissipation term is involved, due to the attractive interaction between the tip and the surface, the model gives a good agreement with the recorded data. particularly, the trends in the phase variations related to the noncontact situations have been found to be amenable to an analysis based upon a simple viscoelastic behavior of the surface. | arxiv:physics/0510098 |
this paper addresses the problem of corpus - level entity typing, i. e., inferring from a large corpus that an entity is a member of a class such as " food " or " artist ". the application of entity typing we are interested in is knowledge base completion, specifically, to learn which classes an entity is a member of. we propose figment to tackle this problem. figment is embedding - based and combines ( i ) a global model that scores based on aggregated contextual information of an entity and ( ii ) a context model that first scores the individual occurrences of an entity and then aggregates the scores. each of the two proposed models has some specific properties. for the global model, learning high quality entity representations is crucial because it is the only source used for the predictions. therefore, we introduce representations using name and contexts of entities on the three levels of entity, word, and character. we show each has complementary information and a multi - level representation is the best. for the context model, we need to use distant supervision since the context - level labels are not available for entities. distant supervised labels are noisy and this harms the performance of models. therefore, we introduce and apply new algorithms for noise mitigation using multi - instance learning. we show the effectiveness of our models in a large entity typing dataset, built from freebase. | arxiv:1708.02275 |
one of the challenges in large - scale information retrieval ( ir ) is to develop fine - grained and domain - specific methods to answer natural language questions. despite the availability of numerous sources and datasets for answer retrieval, question answering ( qa ) remains a challenging problem due to the difficulty of the question understanding and answer extraction tasks. one of the promising tracks investigated in qa is to map new questions to formerly answered questions that are ` similar '. in this paper, we propose a novel qa approach based on recognizing question entailment ( rqe ) and we describe the qa system and resources that we built and evaluated on real medical questions. first, we compare machine learning and deep learning methods for rqe using different kinds of datasets, including textual inference, question similarity and entailment in both the open and clinical domains. second, we combine ir models with the best rqe method to select entailed questions and rank the retrieved answers. to study the end - to - end qa approach, we built the medquad collection of 47, 457 question - answer pairs from trusted medical sources, that we introduce and share in the scope of this paper. following the evaluation process used in trec 2017 liveqa, we find that our approach exceeds the best results of the medical task with a 29. 8 % increase over the best official score. the evaluation results also support the relevance of question entailment for qa and highlight the effectiveness of combining ir and rqe for future qa efforts. our findings also show that relying on a restricted set of reliable answer sources can bring a substantial improvement in medical qa. | arxiv:1901.08079 |
stellar orbits at the galactic center provide a very clean probe of the gravitational potential of the supermassive black hole. they can be studied with unique precision, beyond the confusion limit of a single telescope, with the near - infrared interferometer gravity. imaging is essential to search the field for faint, unknown stars on short orbits which potentially could constrain the black hole spin. furthermore, it provides the starting point for astrometric fitting to derive highly accurate stellar positions. here, we present $ \ mathrm { g ^ r } $, a new imaging tool specifically designed for galactic center observations with gravity. the algorithm is based on a bayesian interpretation of the imaging problem, formulated in the framework of information field theory and building upon existing works in radio - interferometric imaging. its application to gravity observations from 2021 yields the deepest images to date of the galactic center on scales of a few milliarcseconds. the images reveal the complicated source structure within the central $ 100 \, \ mathrm { mas } $ around sgr a *, where we detected the stars s29 and s55 and confirm s62 on its trajectory, slowly approaching sgr a *. furthermore, we were able to detect s38, s42, s60, and s63 in a series of exposures for which we offset the fiber from sgr a *. we provide an update on the orbits of all aforementioned stars. in addition to these known sources, the images also reveal a faint star moving to the west at a high angular velocity. we cannot find any coincidence with any known source and, thus, we refer to the new star as s300. from the flux ratio with s29, we estimate its k - band magnitude as $ m _ \ mathrm { k } \ left ( \ mathrm { s300 } \ right ) \ simeq 19. 0 - 19. 3 $. images obtained with clean confirm the detection. | arxiv:2112.07477 |
classical mechanics can be formulated using a symplectic structure on classical phase space, while quantum mechanics requires a complex - differentiable structure on that same space. complex - differentiable structures on a given real manifold are often not unique. this letter is devoted to analysing the dependence of the notion of a quantum on the complex - differentiable structure chosen on classical phase space. | arxiv:quant-ph/0411166 |
scheduled maintenance is likely to be lengthy and therefore consequential for the economics of fusion power plants. the maintenance strategy that maximizes the economic value of a plant depends on internal factors such as the cost and durability of the replaceable components, the frequency and duration of the maintenance blocks, and the external factors of the electricity system in which the plant operates. this paper examines the value of fusion power plants with various maintenance properties in a decarbonized united states eastern interconnection circa 2050. seasonal variations in electricity supply and demand mean that certain times of year, particularly spring to early summer, are best for scheduled maintenance. seasonality has two important consequences. first, the value of a plant can be 15 % higher than what one would naively expect if value were directly proportional to its availability. second, in some cases, replacing fractions of a component in shorter maintenance blocks spread over multiple years is better than replacing it all at once during a longer outage, even through the overall availability of the plant is lower in the former scenario. | arxiv:2405.01514 |
an optical chopper periodically interrupts a classical light beam. we propose a realizable quantum version of the optical chopper, where the time - periodic driving of the light - matter coupling is achieved through a nonlinear three wave mixing element. we theoretically investigate how our scheme can be used for the controllable shaping of few photon light. using floquet dynamics, we find strong periodic modulations of the transmission and reflection envelopes in the scattered few - photon pulses, including photon compression and blockade, as well as dramatic changes in the quantum light statistics. our theoretical analysis allows us to explain these non - trivial phenomena as arising from non - adiabatic memory effects. | arxiv:1603.05494 |
as far as entanglement is concerned, two density matrices of $ n $ particles are equivalent if they are on the same orbit of the group of local unitary transformations, $ u ( d _ 1 ) \ times... \ times u ( d _ n ) $ ( where the hilbert space of particle $ r $ has dimension $ d _ r $ ). we show that for $ n $ greater than or equal to two, the number of independent parameters needed to specify an $ n $ - particle density matrix up to equivalence is $ \ pi _ r d _ r ^ 2 - \ sum _ r d _ r ^ 2 + n - 1 $. for $ n $ spin - $ { 1 \ over 2 } $ particles we also show how to characterise generic orbits, both by giving an explicit parametrisation of the orbits and by finding a finite set of polynomial invariants which separate the orbits. | arxiv:quant-ph/9801076 |
we introduce a new generalization of the pauli channels using the mutually unbiased measurement operators. the resulting channels are bistochastic but their eigenvectors are not unitary. we analyze the channel properties, such as complete positivity, entanglement breaking, and multiplicativity of maximal output purity. we illustrate our results with the maps constructed from the gell - mann matrices and the heisenberg - weyl observables. | arxiv:2003.12570 |
risk - sharing is one way to pool risks without the need for a third party. to ensure the attractiveness of such a system, the rule should be accepted and understood by all participants. a desirable risk - sharing rule should fulfill actuarial fairness and pareto optimality while being easy to compute. this paper establishes a one - to - one correspondence between an actuarially fair pareto optimal ( afpo ) risk - sharing rule and a fixed point of a specific function. a fast numerical method for computing these risk - sharing rules is also derived. as a result, we are able to compute afpo risk - sharing rules for a large number of heterogeneous participants in this framework. | arxiv:2303.05421 |
for over a century, researchers have wrestled with how to define good driving behavior, and the debate has surfaced anew for automated vehicles ( avs ). we put forth the concept of drivership as a framing for the realization of good driving behaviors. drivership grounds the evaluation of driving behaviors in the alignment between the mutualistic expectations that exist amongst road users. leveraging existing literature, we distinguish empirical expectations ( i. e., reflecting " beliefs that a certain behavior will be followed, " drawing on past experiences ) ( bicchieri, 2006 ) ; and normative expectations ( i. e., reflecting " beliefs that a certain behavior ought to be followed, " based on societally agreed - upon principles ) ( bicchieri, 2006 ). because societal expectations naturally shift over time, we introduce a third type of expectation, furtherance expectations, denoting behavior which could be exhibited to enable continuous improvement of the transportation ecosystem. we position drivership within the space of societal normative expectations, which may overlap with some empirical and furtherance expectations, constrained by what is technologically and physically feasible. additionally, we establish a novel vocabulary to rigorously tackle conversations on stakeholders ' expectations, a key feature of value - sensitive design. we also detail how drivership comprises safety - centric behaviors and what we term socially - aware behaviors ( where there are no clear safety stakes ). drivership supports multiple purposes, including advancing the understanding and evaluation of driving performance through benchmarking based on many criteria. as such, we argue that an appropriate framing of the notion of drivership also underpins the overall development of a safety case. the paper explores these applications under the more general tenet of drivership as a central element to roadway citizenship. | arxiv:2502.08121 |
we develop a new approach for identifying and estimating average causal effects in panel data under a linear factor model with unmeasured confounders. compared to other methods tackling factor models such as synthetic controls and matrix completion, our method does not require the number of time periods to grow infinitely. instead, we draw inspiration from the two - way fixed effect model as a special case of the linear factor model, where a simple difference - in - differences transformation identifies the effect. we show that analogous, albeit more complex, transformations exist in the more general linear factor model, providing a new means to identify the effect in that model. in fact many such transformations exist, called bridge functions, all identifying the same causal effect estimand. this poses a unique challenge for estimation and inference, which we solve by targeting the minimal bridge function using a regularized estimation approach. we prove that our resulting average causal effect estimator is root - n consistent and asymptotically normal, and we provide asymptotically valid confidence intervals. finally, we provide extensions for the case of a linear factor model with time - varying unmeasured confounders. | arxiv:2108.03849 |
we discuss a many - electron hamiltonian with hubbard - like repulsive interaction and linear coupling to the phonon branches, having the cu - o plane of the superconducting cuprates as a paradigm. a canonical transformation extracts an effective two - body problem from the many - body theory. as a prototype system we study the $ \ cu $ cluster, which yields electronic pairing in the hubbard model ; moreover, a standard treatment of the jahn - teller effect predicts distortions that destroy electronic pairing. remarkably, calculations that keep all the electronic spectrum into account show that vibrations are likely to be synergic with electronic pairing, if the coupling to half - breathing modes predominates, as experiments suggest. | arxiv:cond-mat/0401428 |
we consider two independent and stationary measures over $ \ chi ^ \ mathbb { n } $, where $ \ chi $ finite or countable alphabet. for each pair of $ n $ - strings in the product space we define $ t _ n ^ { ( 2 ) } $ as the length of the shortest path connecting one string to the other where the paths are generating by the underlying dynamics of the measure. for ergodic measures with positive entropy we prove that, for almost every pair of realizations $ ( x, y ) $, $ t ^ { ( 2 ) } _ n / n $ concentrates in one, as $ n $ diverges. under mild extra conditions we prove a large deviation principle. this principle is linked to a quantity that compute the similarity between the two measures that we also introduce. we further prove its existence and other properties. we also show that the fluctuations of $ t _ n ^ { ( 2 ) } $ converge ( only ) in distribution to a non - degenerated distribution. several examples are provided for all results. | arxiv:1611.01530 |
probabilistic cellular automata provide a simple framework for the exploration of classical nonequilibrium processes. recently, quantum cellular automata have been proposed that rely on the propagation of a one - dimensional quantum state along a fictitious discrete time dimension via the sequential application of quantum gates. the resulting $ ( 1 + 1 ) $ - dimensional space - time structure makes these automata special cases of feed - forward quantum neural networks. here we show how asynchronism - - introduced via non - commuting gates - - impacts on the collective nonequilibrium behavior of quantum cellular automata. we illustrate this through a simple model, whose synchronous version implements a contact process and features a nonequilibrium phase transition in the directed percolation universality class. non - commuting quantum gates lead to an " asynchronism transition ", i. e. a sudden qualitative change in the phase transition behavior once a certain degree of asynchronicity is surpassed. our results show how quantum effects may lead to abrupt changes of non - equilibrium dynamics, which may be relevant for understanding the role of quantum correlations in neural networks. | arxiv:2201.01557 |
in non - asymptotic learning, variance - type parameters of sub - gaussian distributions are of paramount importance. however, directly estimating these parameters using the empirical moment generating function ( mgf ) is infeasible. to address this, we suggest using the sub - gaussian intrinsic moment norm [ buldygin and kozachenko ( 2000 ), theorem 1. 3 ] achieved by maximizing a sequence of normalized moments. significantly, the suggested norm can not only reconstruct the exponential moment bounds of mgfs but also provide tighter sub - gaussian concentration inequalities. in practice, we provide an intuitive method for assessing whether data with a finite sample size is sub - gaussian, utilizing the sub - gaussian plot. the intrinsic moment norm can be robustly estimated via a simple plug - in approach. our theoretical findings are also applicable to reinforcement learning, including the multi - armed bandit scenario. | arxiv:2303.07287 |
, near the trailing edges of wings, aircraft flight control systems are replaced by slots which emit fluid flows. = = list of stealth aircraft = = f - 117 nighthawk b - 2 spirit f - 22 raptor f - 35 lightning ii j - 20 su - 57 b - 21 raider fc - 31 su - 75 checkmate = = list of stealth helicopters = = boeing – sikorsky rah - 66 comanche hughes 500p = = list of reduced - signature ships = = navy ships worldwide have incorporated signature - reduction features, mostly for the purpose of reducing anti - ship missile detection range and enhancing countermeasure effectiveness rather than actual detection avoidance. such ships include : bhumibol adulyadej - class frigate independence - class littoral combat ship kamorta - class corvette klewang - class fast attack craft kolkata - class destroyer la fayette - class frigate nilgiri - class frigate sachsen - class frigate shahid soleimani - class corvette shivalik - class frigate skjold - class corvette talwar - class frigate tuo chiang - class corvette type 055 destroyer visakhapatnam - class destroyer visby - class corvette zumwalt - class destroyer = = see also = = active camouflage multi - spectral camouflage cloaking device penetration aid = = references = = = = = bibliography = = = " how " stealth " is achieved on f - 117a ". aeronautics. ru. archived from the original on 20 february 2002. dawson, t. w. g. ; kitchen, g. f. ; glider, g. b. ( september 1957 ). measurements of the radar echoing area of the vulcan by the optical simulation method. farnborough, hants, uk : royal aircraft establishment. national archive catalogue file, avia 6 / 20895 doucet, arnaud ; freitas, nando de ; gordon, neil ( 2001 ) [ 2001 ]. sequential monte carlo methods in practice. statistics for engineering and information science ( 1st ed. ). berlin : springer - verlag. isbn 978 - 0 - 387 - 95146 - 1. retrieved 11 march 2009. gal - or, benjamin ( 1990 ). " multiaxis thrust vectoring flight control vs catastrophic failure prevention ". vectored propulsion, supermanoeuvreability, and robot aircraft. reports to u. s. dept. of transportation / faa, technical center, acd - 210, faa x88 / 0 / 6fa / 921000 / 410 | https://en.wikipedia.org/wiki/Stealth_technology |
in this paper, starting from the updated time series of global temperature anomalies, ta, we show how the solar component affects the observed behavior using, as an indicator of solar activity, the solar sunspot number ssn. the results that are found clearly show that the solar component has an important role and affects significantly the current observed stationary behavior of global temperature anomalies. the solar activity behavior and its future role will therefore be decisive in determining whether or not the restart of the increase of temperature anomalies observed since 1975 will occur. | arxiv:1512.01075 |
existing techniques for training language models can be misaligned with the truth : if we train models with imitation learning, they may reproduce errors that humans make ; if we train them to generate text that humans rate highly, they may output errors that human evaluators can ' t detect. we propose circumventing this issue by directly finding latent knowledge inside the internal activations of a language model in a purely unsupervised way. specifically, we introduce a method for accurately answering yes - no questions given only unlabeled model activations. it works by finding a direction in activation space that satisfies logical consistency properties, such as that a statement and its negation have opposite truth values. we show that despite using no supervision and no model outputs, our method can recover diverse knowledge represented in large language models : across 6 models and 10 question - answering datasets, it outperforms zero - shot accuracy by 4 \ % on average. we also find that it cuts prompt sensitivity in half and continues to maintain high accuracy even when models are prompted to generate incorrect answers. our results provide an initial step toward discovering what language models know, distinct from what they say, even when we don ' t have access to explicit ground truth labels. | arxiv:2212.03827 |
we report on an energy - sensitive imaging detector for studying the fragmentation of polyatomic molecules in the dissociative recombination of fast molecular ions with electrons. the system is based on a large area ( 10 cm x 10 cm ) position - sensitive, double - sided si - strip detector with 128 horizontal and 128 vertical strips, whose pulse height information is read out individually. the setup allows to uniquely identify fragment masses and is thus capable of measuring branching ratios between different fragmentation channels, kinetic energy releases, as well as breakup geometries, as a function of the relative ion - electron energy. the properties of the detection system, which has been installed at the tsr storage ring facility of the max - planck institute for nuclear physics in heidelberg, is illustrated by an investigation of the dissociative recombination of the deuterated triatomic hydrogen cation d2h +. a huge isotope effect is observed when comparing the relative branching ratio between the d2 + h and the hd + d channel ; the ratio 2b ( d2 + h ) / b ( hd + d ), which is measured to be 1. 27 + / - 0. 05 at relative electron - ion energies around 0 ev, is found to increase to 3. 7 + / - 0. 5 at ~ 5 ev. | arxiv:1003.5101 |
let $ x = sl _ 3 ( \ r ) / so ( 3 ) $. let $ \ cal dfr $ be the space of discrete faithful representations of the modular group into $ { \ rm isom \ / } ( x ) $ which map the order $ 2 $ generator to an isometry with a unique fixed point. i prove many things about the component $ \ cal b $ of $ \ cal dfr $ known as the barbot component : it is homeomorphic to $ \ r ^ 2 \ times [ 0, \ infty ) $. the boundary parametrizes the pappus representations from [ { \ bf s0 \ / } ]. the interior parametrizes the complete extension of the family of anosov representations from [ { \ bf blv \ / } ]. the members of $ \ cal b $ are isometry groups of embedded patterns of geodesics in $ x $ which have asymptotic properties like the edges of the farey triangulation or shears thereof. the anosov representations are obtained from the pappus representations by either of two shearing operations in $ x $. the shearing structure is encoded by two proper foliations of $ \ cal b $ into rays. | arxiv:2412.18457 |
a recent work ( 2014 new j. phys. 16 013006 ) claims that nonmonotonic structures found in the many - particle quantum - to - classical transition ( 2013 proc. natl acad. sci. usa 110 1227 - 1231 ; 2011 phys. rev. a 83 062111 ) are not exclusive to the many - body domain, but they also appear for single - photon as well as for semi - classical systems. we show that these situations, however, do not incorporate any quantum - to - classical transition, which makes the claims unsustainable. | arxiv:1407.1758 |
decentralized applications developed using blockchain technology provide innovative business models to serve the human race and solve existing challenges. climate change is one of the biggest problems humanity is facing and there is a dearth of solutions in tackling this grave impediment to the long - term sustainability of our planet. accountability, greenwashing, traceability, impact assessment and trading of carbon credits are unresolved issues in the esg sector. in this paper, we present a novel decentralized application software, dcarbonx, that solves the enumerated problems using nfts on the blockchain platform, through smart contracts. the paper describes the functional architecture of dcarbonx, while elaborating on its salient features and utility in sustainable finance, in particular green sukuk. dcarbonx is a pioneering software providing an exchange for trading of carbon credits. the software facilitates logging of impact and traceable transactions in a carbon market, that would help to prevent duplication of records and greenwashing. the paper discusses the efforts being undertaken to achieve the climate goals as per the paris agreement and also highlights the pivotal obstacles to achieving carbon neutrality by 2050, as per cop26. the paper also encompasses a study on the applications of dapps in defi, web 3. 0 and esg, among other areas and gives a comparative analysis of blockchain platforms for dapp development. the paper is also a pioneer in highlighting the challenges that plague dapp development, deployment and usage. | arxiv:2203.09508 |
we present a systematic investigation of the crystal and electronic structure and the magnetic properties above and below the metal - insulator transition of ball - milled vo $ _ 2 $ nanoparticles and vo $ _ 2 $ microparticles. for this research, we performed a rietveld analysis of synchrotron radiation x - ray diffraction data, o $ k $ x - ray absorption spectroscopy, v $ l _ 3 $ resonant inelastic x - ray scattering, and magnetic susceptibility measurements. this study reveals an unusual low - temperature phase that involves the formation of an elongated and less - tilted v - v pair, a narrowed energy gap, and an induced paramagnetic contribution from the nanoparticles. we show that the change in the crystal structure is consistent with the change in the electronic states around the fermi level, which leads us to suggest that the peierls mechanism contributes to the energy splitting of the $ a _ { 1g } $ state. furthermore, we find that the high - temperature rutile structure of the nanoparticles is almost identical to that of the microparticles. | arxiv:1006.1943 |
by the density functional theory for crystallization, it is shown that for vortex lines in an underlying layered structure a smectic phase with period m = 2 can be stabilized by strong layer pinning. the freezing of vortex liquid is then two - step, a second - order liquid - smectic transition and a first - order smectic - lattice transition. dft also indicates that a direct, first - order liquid - lattice transition preempts the smectic order with m > 2 irrespectively of the pinning strength. possible h - t phase diagrams are mapped out. implications of the dft results to the interlayer josephson vortex system in high - tc cuprates are given. | arxiv:cond-mat/0406180 |
on the basis of additive schemes ( splitting schemes ) we construct efficient numerical algorithms to solve approximately the initial - boundary value problems for systems of time - dependent partial differential equations ( pdes ). in many applied problems the individual components of the vector of unknowns are coupled together and then splitting schemes are applied in order to get a simple problem for evaluating components at a new time level. typically, the additive operator - difference schemes for systems of evolutionary equations are constructed for operators coupled in space. in this paper we investigate more general problems where coupling of derivatives in time for components of the solution vector takes place. splitting schemes are developed using an additive representation for both the primary operator of the problem and the operator at the time derivative. splitting schemes are based on a triangular two - component representation of the operators. | arxiv:1112.1294 |
we review the basic properties of the haldane phase in spin - 1 heisenberg antiferromagnetic chains, including its persistence in quasi - one - dimensional geometries. using large - scale numerical simulations, we map out the phase diagram for a realistic model applicable to experimental haldane compounds. we also investigate the effect of different chain coupling geometries and confirm a general mean field universality of the critical coupling times the coordination number of the lattice. inspired by the recent development of characterization of symmetry protected topological states, of which the haldane phase of spin - 1 heisenberg antiferromagnetic chain is a preeminent example, we provide direct evidence that the quasi - one - dimensional haldane phase is indeed a non - trivial symmetry protected topological state. | arxiv:1501.00422 |
in this paper, we derive a temporal arbitrage policy for storage via reinforcement learning. real - time price arbitrage is an important source of revenue for storage units, but designing good strategies have proven to be difficult because of the highly uncertain nature of the prices. instead of current model predictive or dynamic programming approaches, we use reinforcement learning to design an optimal arbitrage policy. this policy is learned through repeated charge and discharge actions performed by the storage unit through updating a value matrix. we design a reward function that does not only reflect the instant profit of charge / discharge decisions but also incorporate the history information. simulation results demonstrate that our designed reward function leads to significant performance improvement compared with existing algorithms. | arxiv:1711.03127 |
despite many accomplishments by legged robot designers, state - of - the - art bipedal robots are prone to falling over, cannot negotiate extremely rough terrains and cannot directly regulate unilateral contact forces. our objective is to integrate merits of legged and aerial robots in a single platform. we will show that the thrusters in a bipedal legged robot called harpy can be leveraged to stabilize the robot ' s frontal dynamics and permit jumping over large obstacles which is an unusual capability not reported before. in addition, we will capitalize on the thrusters action in harpy and will show that one can avoid using costly optimization - based schemes by directly regulating contact forces using an reference governor ( rgs ). we will resolve gait parameters and re - plan them during gait cycles by only assuming well - tuned supervisory controllers. then, we will focus on rg - based fine - tuning of the joints desired trajectories to satisfy unilateral contact force constraints. | arxiv:2103.15952 |
the jeffreys model ( also associated with the names of lethersich and oldroyd ) is one of the crucial conceptions in the theory of viscoelastic fluids. the models of jeffreys type describe behaviour of bitumens, blood, polymers and their solutions, dough, the earth ' s crust, concrete, lubricants etc. study of bvps corresponding to their statics and dynamics meets a lot of mathematical difficulties, which turn out to be much harder than the ones that are related to the celebrated navier - stokes system. in this work, we make an attempt to review the recent results and main unsolved problems for equations of motion for the mediums of jeffreys ' type. | arxiv:0911.2206 |
the many peculiarities of ap stars ( not only chemical ones, but also magnetic field and slow rotation ) may vary during the main - sequence evolution of these stars. we review here briefly the evidences found in the last thirty years for such evolution, with an emphasis on the more recent research. the position in the hr diagram of low mass ap stars with a significant surface magnetic field ( as measured by us ) is reviewed as well. | arxiv:0804.0711 |
we investigate the emergence of induced localized coupled modes in passive cavities with both loss and gain. our model is based on linearly coupled lugiato - lefever equations, where a gaussian pump beam is applied to only one mode. through numerical simulations, we demonstrate that self - defocusing systems can support the formation of localized stationary modes in the partner field. the characteristics of these induced modes are determined by key parameters, including coupling strength, cavity decay rate, detuning effects, and the pump beam ' s intensity and width. | arxiv:2502.07561 |
we characterize the differentiable points of the distance function from a closed subset $ n $ of an arbitrary dimensional finsler manifold in terms of the number of $ n $ - segments. in the case of a 2 - dimensional finsler manifold, we prove the structure theorem of the cut locus of a closed subset $ n $, namely that it is a local tree, it is made of countably many rectifiable jordan arcs except for the endpoints of the cut locus and that an intrinsic metric can be introduced in the cut locus and its intrinsic and induced topologies coincide. we should point out that these are new results even for riemannian manifolds. | arxiv:1207.0918 |
the effects of neutron irradiation on materials are often interpreted in terms of atomic recoils, initiated by neutron impacts and producing crystal lattice defects. in addition, there is a remarkable two - step process, strongly pronounced in the medium - weight and heavy elements. this process involves the generation of energetic { \ gamma } photons in nonelastic collisions of neutrons with atomic nuclei, achieved via capture and inelastic reactions. subsequently, high - energy electrons are excited through the scattering of { \ gamma } photons by the atomic electrons. we derive and validate equations enabling a fast and robust evaluation of photon and electron fluxes produced by the neutrons in the bulk of materials. the two - step n - { \ gamma } - e scattering creates a nonequilibrium dynamically fluctuating steady - state population of high - energy electrons, with the spectra of photon and electron energies extending well into the mega - electron - volt range. this stimulates vacancy diffusion through electron - triggered atomic recoils, primarily involving vacancy - impurity dissociation, even if thermal activation is ineffective. tungsten converts the energy of fusion or fission neutrons into a flux of { \ gamma } radiation at the conversion efficiency approaching 99 %, with implications for structural materials, superconductors, and insulators, as well as phenomena like corrosion, and helium and hydrogen isotope retention. | arxiv:2210.09667 |
we describe, in the detection of multi - sample aligned sparse signals, the critical boundary separating detectable from nondetectable signals, and construct tests that achieve optimal detectability : penalized versions of the berk - jones and the higher - criticism test statistics evaluated over pooled scans, and an average likelihood ratio over the critical boundary. we show in our results an inter - play between the scale of the sequence length to signal length ratio, and the sparseness of the signals. in particular the difficulty of the detection problem is not noticeably affected unless this ratio grows exponentially with the number of sequences. we also recover the multiscale and sparse mixture testing problems as illustrative special cases. | arxiv:1510.03659 |
the tunneling time is here investigated by means of an electromagnetic model, for a system where a gap, between two parallel planes, acts as a classically - forbidden region for an impinging pulse with incidence angle larger than the critical angle. in all cases of frustrated total reflection we obtain a superluminal behavior both for phase and group delays. | arxiv:physics/0111192 |
we have investigated both theoretically and experimentally dipolar relaxation in a gas of magnetically trapped chromium atoms. we have found that the large magnetic moment of 6 $ \ mu _ b $ results in an event rate coefficient for dipolar relaxation processes of up to $ 3. 2 \ cdot10 ^ { - 11 } $ cm $ ^ { 3 } $ s $ ^ { - 1 } $ at a magnetic field of 44 g. we present a theoretical model based on pure dipolar coupling, which predicts dipolar relaxation rates in agreement with our experimental observations. this very general approach can be applied to a large variety of dipolar gases. | arxiv:quant-ph/0307184 |
for hot spots compressed at constant velocity, we give a hydrodynamic stability criterion that describes the expected energy behavior of non - radial hydrodynamic motion for different classes of trajectories ( in $ \ rho r $ - - - $ t $ space ). for a given compression velocity, this criterion depends on $ \ rho r $, $ t $, and $ \ mathrm { d } t / \ mathrm { d } ( \ rho r ) $ ( the trajectory slope ), and applies point - wise, so that the expected behavior can be determined instantaneously along the trajectory. among the classes of trajectories are those where the hydromotion is guaranteed to decrease, and those where the hydromotion is bounded by a saturated value. we calculate this saturated value, and find the compression velocities for which hydromotion may be a substantial fraction of hot - spot energy at burn time. the lindl " attractor " trajectory ( lindl, 1995 ) is shown to experience non - radial hydrodynamic energy that grows towards this saturated state. comparing the saturation value to available detailed 3d simulation results, we find that the fluctuating velocities in these simulations reach substantial fractions of the saturated value. | arxiv:1802.06817 |
generative ai ' s expanding footprint across numerous industries has led to both excitement and increased scrutiny. this paper delves into the unique security challenges posed by generative ai, and outlines potential research directions for managing these risks. | arxiv:2402.12617 |
a deeper understanding of recent computations of the brauer group of hopf algebras is attained by explaining why a direct product decomposition for this group holds and describing the non - interpreted factor occurring in it. for a hopf algebra $ b $ in a braided monoidal category $ \ c $, and under certain assumptions on the braiding ( fulfilled if $ \ c $ is symmetric ), we construct a sequence for the brauer group $ \ bm ( \ c ; b ) $ of $ b $ - module algebras, generalizing beattie ' s one. it allows one to prove that $ \ bm ( \ c ; b ) \ cong \ br ( \ c ) \ times \ gal ( \ c ; b ), $ where $ \ br ( \ c ) $ is the brauer group of $ \ c $ and $ \ gal ( \ c ; b ) $ the group of $ b $ - galois objects. we also show that $ \ bm ( \ c ; b ) $ contains a subgroup isomorphic to $ \ br ( \ c ) \ times \ hc ( \ c ; b, i ), $ where $ \ hc ( \ c ; b, i ) $ is the second sweedler cohomology group of $ b $ with values in the unit object $ i $ of $ \ c $. these results are applied to the brauer group of a quasi - triangular hopf algebra that is a radford biproduct $ b \ times h $, where $ h $ is a usual hopf algebra over a field $ k $, the hopf subalgebra generated by the quasi - triangular structure $ \ r $ is contained in $ h $ and $ b $ is a hopf algebra in the category $ { } _ h \ m $ of left $ h $ - modules. the hopf algebras whose brauer group was recently computed fit this framework. we finally show that $ \ bm ( k, h, \ r ) \ times \ hc ( { } _ h \ m ; b, k ) $ is a subgroup of the brauer group $ \ bm ( k, b \ times h, \ r ), $ confirming the suspicion that a certain cohomology group of $ b \ times h $ ( second lazy cohomology group was conjectured ) embeds into $ \ bm ( k, b \ times h, \ r ). $ new examples of brauer groups of quasi | arxiv:0809.2517 |
we report on the structural, magnetic, and electronic properties of two new double - perovskites synthesized under high pressure ; pb2caoso6 and pb2znoso6. upon cooling below 80 k, pb2caoso6 simultaneously undergoes a metal - - insulator transition and develops antiferromagnetic order. pb2znoso6, on the other hand, remains a paramagnetic metal down to 2 k. the key difference between the two compounds lies in their crystal structure. the os atoms in pb2znoso6 are arranged on an approximately face - centred cubic lattice with strong antiferromagnetic nearest - neighbor exchange couplings. the geometrical frustration inherent to this lattice prevents magnetic order from forming down to the lowest temperatures. in contrast, the unit cell of pb2caoso6 is heavily distorted up to at least 500 k, including antiferroelectric - like displacements of the pb and o atoms despite metallic conductivity above 80 k. this distortion relieves the magnetic frustration, facilitating magnetic order which in turn drives the metal - - insulator transition. our results suggest that the phase transition in pb2caoso6 is spin - driven, and could be a rare example of a slater transition. | arxiv:2009.04196 |
weyl fermions with tilted linear dispersions characterized by several different velocities appear in some systems including the quasi - two - dimensional organic semiconductor $ \ alpha $ - ( bedt - ttf ) $ _ 2 $ i $ _ 3 $ and three - dimensional wte $ _ 2 $. the coulomb interaction between electrons modifies the velocities in an essential way in the low - energy limit, where the logarithmic corrections dominate. taking into account the coupling to both the transverse and longitudinal electromagnetic fields, we derive the renormalization group equations for the velocities of the tilted weyl fermions in two dimensions, and found that they increase as the energy decreases and eventually hit the speed of light $ c $ to result in the cherenkov radiation. especially, the system restores the isotropic weyl cone even when the bare weyl cone is strongly tilted and the velocity of electrons becomes negative in certain directions. | arxiv:1512.08704 |
we study the faint end of the hi mass function ( himf ) in order to test the predictions of the cdm theory on the number density of objects with small ( dark ) masses. the neutral hydrogen is much better tracer of the underlying mass distribution compared to the luminous matter and can be used to test the existence of a population of small galaxies in which the star formation has been partially or completely suppressed during cosmic evolution. due to technical limitations, the existing hi surveys are not very sensitive to hi masses below 10 ^ 8 m _ sun. we designed a blind hi survey to be sensitive to objects with small hi masses. the surveyed area is in the canis venatici groups of galaxies and covers in total ~ 86 deg ^ 2 of sky, with observed velocities in the range - 350 < cz < 1400 km / s. we detected 69 objects, 22 of them for the first time in hi. all new hi detections fall in the lower part of the mass - histogram, confirming our ability to detect galaxies with small hi masses. the calculated himf is flat in the faint end regime ( slope ~ - 1 ), different from the steep rise predicted by cdm models. possible effects of the environment on the estimated himf parameters are discussed. | arxiv:astro-ph/0508072 |
surface stress and surface energy are two fundamental parameters that determine the surface properties of any materials. while it is commonly believed that the surface stress and surface energy of liquids are identical, the relationship between the two parameters in soft polymeric gels remains debatable. in this work, we measured the surface stress and surface energy of soft silicone gels with varying weight ratios of crosslinkers in soft wetting experiments. above a critical density, $ k _ 0 $, the surface stress was found to increase significantly with crosslinking density while the surface energy remained unchanged. in this regime, we can estimate a non - zero surface elastic modulus that also increases with the ratio of crosslinkers. by comparing the surface mechanics of the soft gels with their bulk rheology, the surface properties near the critical density $ k _ 0 $ were found to be closely related to the underlying percolation transition of the polymer networks. | arxiv:2106.03333 |
graph states are the backbone of measurement - based continuous - variable quantum computation. however, experimental realisations of these states induce gaussian measurement statistics for the field quadratures, which poses a barrier to obtain a genuine quantum advantage. in this letter, we propose mode - selective photon addition and subtraction as viable and experimentally feasible pathways to introduce non - gaussian features in such continuous - variable graph states. in particular, we investigate how the non - gaussian properties spread among the vertices of the graph, which allows us to show the degree of control that is achievable in this approach. | arxiv:1804.09444 |
the effective coupling of two distant quantum dots through virtual photon exchange in a semiconductor microcavity is studied. the experimental conditions for strong coupling and its manifestation in the spectra of emission are analyzed. | arxiv:1007.1784 |
we addressed the challenging task of video question answering, which requires machines to answer questions about videos in a natural language form. previous state - of - the - art methods attempt to apply spatio - temporal attention mechanism on video frame features without explicitly modeling the location and relations among object interaction occurred in videos. however, the relations between object interaction and their location information are very critical for both action recognition and question reasoning. in this work, we propose to represent the contents in the video as a location - aware graph by incorporating the location information of an object into the graph construction. here, each node is associated with an object represented by its appearance and location features. based on the constructed graph, we propose to use graph convolution to infer both the category and temporal locations of an action. as the graph is built on objects, our method is able to focus on the foreground action contents for better video question answering. lastly, we leverage an attention mechanism to combine the output of graph convolution and encoded question features for final answer reasoning. extensive experiments demonstrate the effectiveness of the proposed methods. specifically, our method significantly outperforms state - of - the - art methods on tgif - qa, youtube2text - qa, and msvd - qa datasets. code and pre - trained models are publicly available at : https : / / github. com / sundoge / l - gcn | arxiv:2008.09105 |
manycore processors feature a high number of general - purpose cores designed to work in a multithreaded fashion. recent manycore processors are kept coherent using scalable distributed directories. a paramount example is the intel mesh interconnect, which consists of a network - on - chip interconnecting " tiles ", each of which contains computation cores, local caches, and coherence masters. the distributed coherence subsystem must be queried for every out - of - tile access, imposing an overhead on memory latency. this paper studies the physical layout of an intel knights landing processor, with a particular focus on the coherence subsystem, and uncovers the pseudo - random mapping function of physical memory blocks across the pieces of the distributed directory. leveraging this knowledge, candidate optimizations to improve memory latency through the minimization of coherence traffic are studied. although these optimizations do improve memory throughput, ultimately this does not translate into performance gains due to inherent overheads stemming from the computational complexity of the mapping functions. | arxiv:2011.05422 |
transport of cold atoms in shallow optical lattices is characterized by slow, nonstationary momentum relaxation. we here develop a projector operator method able to derive in this case a generalized smoluchowski equation for the position variable. we show that this explicitly non - markovian equation can be written as a systematic expansion involving higher - order derivatives. we use the latter to compute arbitrary moments of the spatial distribution and analyze their multifractal properties. | arxiv:1202.2653 |
we present the results of analytical evaluation of the indirect rkky interaction in a layered metal with nearly nested ( almost squared ) fermi surface. the final expressions are obtained in closed form as a combination of bessel functions. we discuss the notion of the ` ` 2k _ f ' ' oscillations and show that they occur as the far asymptote of our expressions. we show the existence of the intermediate asymptote of the interaction which is of the sign - reversal antiferromagnetic type and is the only term surviving in the limit of exact nesting. a good accordance of our analytical formulas with numerical findings is demonstrated until the interatomic distances. the obtained expressions for the green ' s functions extend the previous analytical results into the region of intermediate distances as well. | arxiv:cond-mat/9709090 |
a new pair of asymptotic invariants for finitely presented groups, called intrinsic and extrinsic tame filling functions, are introduced. these filling functions are quasi - isometry invariants that strengthen the notions of intrinsic and extrinsic diameter functions for finitely presented groups. we show that the existence of a ( finite - valued ) tame filling function implies that the group is tame combable. bounds on both intrinsic and extrinsic tame filling functions are discussed for stackable groups, including groups with a finite complete rewriting system, thompson ' s group f, and almost convex groups. | arxiv:1410.2669 |
a unique parametrization of secondary ( thermal ) dilepton yields in heavy - ion experiments at cern - sps is proposed. this parametrization resembles a thermal $ q \ bar q $ annihilation rate. this is inspired by the observation that lepton pair production rates are quantitatively similar, whether expressed in a hadronic or partonic basis. adding the thermal yield and the background contributions ( hadronic cocktail, drell - yan, correlated semileptonic decays of open charm ) the spectral shapes of the ceres / na45, na38, na50 and helios / 3 data from experiments with lead and sulfur beams can be well described. | arxiv:hep-ph/0010332 |
the mutual fund theorem ( mft ) is considered in a general semimartingale financial market s with a finite time horizon t, where agents maximize expected utility of terminal wealth. it is established that : 1 ) let n be the wealth process of the num \ ' eraire portfolio ( i. e. the optimal portfolio for the log utility ). if any path - independent option with maturity t written on the num \ ' eraire portfolio can be replicated by trading \ emph { only } in n, then the ( mft ) holds true for general utility functions, and the num \ ' eraire portfolio may serve as mutual fund. this generalizes merton ' s classical result on black - scholes markets. conversely, under a supplementary weak completeness assumption, we show that the validity of the ( mft ) for general utility functions implies the same replicability property for options on the num \ ' eraire portfolio described above. 2 ) if for a given class of utility functions ( i. e. investors ) the ( mft ) holds true in all complete brownian financial markets s, then all investors use the same utility function u, which must be of hara type. this is a result in the spirit of the classical work by cass and stiglitz. | arxiv:0710.1909 |
sliding - window aggregation is a widely - used approach for extracting insights from the most recent portion of a data stream. the aggregations of interest can usually be expressed as binary operators that are associative but not necessarily commutative nor invertible. non - invertible operators, however, are difficult to support efficiently. in a 2017 conference paper, we introduced daba, the first algorithm for sliding - window aggregation with worst - case constant time. before daba, if a window had size $ n $, the best published algorithms would require $ o ( \ log n ) $ aggregation steps per window operation - - - and while for strictly in - order streams, this bound could be improved to $ o ( 1 ) $ aggregation steps on average, it was not known how to achieve an $ o ( 1 ) $ bound for the worst - case, which is critical for latency - sensitive applications. this article is an extended version of our 2017 paper. besides describing daba in more detail, this article introduces a new variant, daba lite, which achieves the same time bounds in less memory. whereas daba requires space for storing $ 2n $ partial aggregates, daba lite only requires space for $ n + 2 $ partial aggregates. our experiments on synthetic and real data support the theoretical findings. | arxiv:2009.13768 |
we present accurate measurements of the linear, quadratic, and cubic local bias of dark matter halos, using curved " separate universe " n - body simulations which effectively incorporate an infinite - wavelength overdensity. this can be seen as an exact implementation of the peak - background split argument. we compare the results with the linear and quadratic bias measured from the halo - matter power spectrum and bispectrum, and find good agreement. on the other hand, the standard peak - background split applied to the sheth & tormen ( 1999 ) and tinker et al. ( 2008 ) halo mass functions matches the measured linear bias parameter only at the level of 10 %. the prediction from the excursion set - peaks approach performs much better, which can be attributed to the stochastic moving barrier employed in the excursion set - peaks prediction. we also provide convenient fitting formulas for the nonlinear bias parameters $ b _ 2 ( b _ 1 ) $ and $ b _ 3 ( b _ 1 ) $, which work well over a range of redshifts. | arxiv:1511.01096 |
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