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we propose an alternative scenario for the axion misalignment mechanism based on the nontrivial interplay between the axion and a light dilaton in the early universe. dark matter abundance is still sourced by the initial misalignment of the axion field, whose motion along the potential kicks the dilaton field away from its minimum, and dilaton starts to oscillate later with a delayed onset time for oscillation and a relatively large misalignment value due to the kick ; eventually the dilaton dominates over the axion in their energy densities, and the dilaton is identified as dark matter. the kick effect due to axion motion is the most significant if the initial field value of dilaton is near its minimum ; therefore, we call this scenario axion free - kick misalignment mechanism, where axion plays the role similar to a football player. dark matter abundance can be obtained with a lower axion decay constant compared to the conventional misalignment mechanism.
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arxiv:2211.13074
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hanle magnetoresistance ( hmr ) is a type of magnetoresistance where interplay of the spin hall effect, hanle - type spin precession, and spin - dependent scattering at the top / bottom surfaces in a heavy metal controls the effect. in this study, we modulate hmr in ultrathin pt by ionic gating, where the surface rashba field created by a strong electric field at the interface between the ionic gate and pt plays the dominant role in the modulation. this finding can facilitate investigations of gate - tunable, spin - related effects and fabrication of spin devices.
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arxiv:2302.08096
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models play an important role in our understanding of the global structure of the solar wind and its interaction with the interstellar medium. a critical ingredient in many types of models are the charge - exchange collisions between ions and neutrals. some ambiguity exists in the charge - exchange cross - section for protons and hydrogen atoms, depending on which experimental data is used. the differences are greatest at low energies, and for the plasma - neutral interaction in the outer heliosheath may exceed 50 \ %. in this paper we assess a number of existing data sets and formulae for proton - hydrogen charge - exchange. we use a global simulation of the heliosphere to quantify the differences between the currently favored cross - section, and a formulation we suggest that more closely matches the majority of available data. we find that in order to make the resulting two heliospheres the same size, the interstellar proton and hydrogen densities need to be adjusted by 10 to 15 \ %, which provides a way to link the uncertainty in the cross - section to the uncertainty in the parameters of the pristine interstellar plasma.
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arxiv:1911.09823
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we present new results of our ongoing project toward a precision determination of the kaon $ b $ parameter with the kogut - susskind quark action in quenched qcd. new results taken at $ \ beta $ = 6. 4 and $ \ beta = 5. 7 $ suggest that an apparently linear $ a $ dependence of $ b _ k $ previously observed for $ \ beta = 5. 85 - 6. 2 $ arises from a change of curvature from convex to concave as the lattice spacing is reduced. fitting data for $ \ beta \ geq 5. 93 $ with an $ o ( a ^ 2 ) $ form yields $ b _ k $ ( ndr, 2 gev ) = 0. 587 ( 7 ) ( 17 ) in the continuum limit. we also describe a finite - size study of $ b _ k $ at $ \ beta = $ 6. 0 and 6. 4, and a reanalysis of the theoretical argument for $ o ( a ^ 2 ) $ behavior.
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arxiv:hep-lat/9608134
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given a reductive lie algebra over the complex numbers, we introduce a family of category which generalises the bgg category $ \ mathcal { o } $. we also classify the simple modules for some of these categories and prove a semisimplicity result.
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arxiv:0912.3242
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the asymptotic normality of the maximum likelihood estimator ( mle ) under regularity conditions is a cornerstone of statistical theory. in this paper, we give explicit upper bounds on the distributional distance between the distribution of the mle of a vector parameter, and the multivariate normal distribution. we work with possibly high - dimensional, independent but not necessarily identically distributed random vectors. in addition, we obtain explicit upper bounds even in cases where the mle cannot be expressed analytically.
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arxiv:1510.03679
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the nodal domains of eigenvectors of the discrete schrodinger operator on simple, finite and connected graphs are considered. courant ' s well known nodal domain theorem applies in the present case, and sets an upper bound to the number of nodal domains of eigenvectors : arranging the spectrum as a non decreasing sequence, and denoting by $ \ nu _ n $ the number of nodal domains of the $ n $ ' th eigenvector, courant ' s theorem guarantees that the nodal deficiency $ n - \ nu _ n $ is non negative. ( the above applies for generic eigenvectors. special care should be exercised for eigenvectors with vanishing components. ) the main result of the present work is that the nodal deficiency for generic eigenvectors equals to a morse index of an energy functional whose value at its relevant critical points coincides with the eigenvalue. the association of the nodal deficiency to the stability of an energy functional at its critical points was recently discussed in the context of quantum graphs [ arxiv : 1103. 1423 ] and dirichlet laplacian in bounded domains in $ r ^ d $ [ arxiv : 1107. 3489 ]. the present work adapts this result to the discrete case. the definition of the energy functional in the discrete case requires a special setting, substantially different from the one used in [ arxiv : 1103. 1423, arxiv : 1107. 3489 ] and it is presented here in detail.
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arxiv:1110.3802
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in earlier versions of the community discovering problem, the overlap between communities was restricted by a simple count upper - bound [ 17, 5, 11, 8 ]. in this paper, we introduce the $ \ pi $ - packing with $ \ alpha ( ) $ - overlap problem to allow for more complex constraints in the overlap region than those previously studied. let $ \ mathcal { v } ^ r $ be all possible subsets of vertices of $ v ( g ) $ each of size at most $ r $, and $ \ alpha : \ mathcal { v } ^ r \ times \ mathcal { v } ^ r \ to \ { 0, 1 \ } $ be a function. the $ \ pi $ - packing with $ \ alpha ( ) $ - overlap problem seeks at least $ k $ induced subgraphs in a graph $ g $ subject to : ( i ) each subgraph has at most $ r $ vertices and obeys a property $ \ pi $, and ( ii ) for any pair $ h _ i, h _ j $, with $ i \ neq j $, $ \ alpha ( h _ i, h _ j ) = 0 $ ( i. e., $ h _ i, h _ j $ do not conflict ). we also consider a variant that arises in clustering applications : each subgraph of a solution must contain a set of vertices from a given collection of sets $ \ mathcal { c } $, and no pair of subgraphs may share vertices from the sets of $ \ mathcal { c } $. in addition, we propose similar formulations for packing hypergraphs. we give an $ o ( r ^ { rk } k ^ { ( r + 1 ) k } n ^ { cr } ) $ algorithm for our problems where $ k $ is the parameter and $ c $ and $ r $ are constants, provided that : i ) $ \ pi $ is computable in polynomial time in $ n $ and ii ) the function $ \ alpha ( ) $ satisfies specific conditions. specifically, $ \ alpha ( ) $ is hereditary, applicable only to overlapping subgraphs, and computable in polynomial time in $ n $. motivated by practical applications we give several examples of $ \ alpha ( ) $ functions which meet those conditions.
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arxiv:1601.03676
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it is thought that planetary mass companions may form through gravitational disk instabilities or core accretion. identifying such objects in the process of formation would provide the most direct test for the competing formation theories. one of the most promising candidates for a planetary mass object still in formation is the third object in the fw tau system. we here present alma cycle 1 observations confirming the recently published 1. 3 mm detection of a dust disk around this third object and present for the first time a clear detection of a single peak $ ^ { 12 } $ co ( 2 - 1 ) line, providing direct evidence for the simultaneous existence of a gas disk. we perform radiative transfer modeling of the third object in fw tau and find that current observations are consistent with either a brown dwarf embedded in an edge - on disk or a planet embedded in a low inclination disk, which is externally irradiated by the binary companion. further observations with alma, aiming for high snr detections of non contaminated gas lines, are required to conclusively unveil the nature of the third object in fw tau.
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arxiv:1504.05644
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we propose unified visual - semantic embeddings ( univse ) for learning a joint space of visual and textual concepts. the space unifies the concepts at different levels, including objects, attributes, relations, and full scenes. a contrastive learning approach is proposed for the fine - grained alignment from only image - caption pairs. moreover, we present an effective approach for enforcing the coverage of semantic components that appear in the sentence. we demonstrate the robustness of unified vse in defending text - domain adversarial attacks on cross - modal retrieval tasks. such robustness also empowers the use of visual cues to resolve word dependencies in novel sentences.
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arxiv:1904.05521
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esports industry has greatly progressed within the last decade in terms of audience and fund rising, broadcasting, networking and hardware. since the number and quality of professional team has evolved too, there is a reasonable need in improving skills and training process of professional esports athletes. in this work, we demonstrate a system able to collect heterogeneous data ( physiological, environmental, video, telemetry ) and guarantying synchronization with 10 ms accuracy. in particular, we demonstrate how to synchronize various sensors and ensure post synchronization, i. e. logged video, a so - called demo file, with the sensors data. our experimental results achieved on the cs : go game discipline show up to 3 ms accuracy of the time synchronization of the gaming computer.
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arxiv:1908.06404
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the online event selection is crucial to reject most of the events containing uninteresting background collisions while preserving as much as possible the interesting physical signals. the b - jet selection is part of the trigger strategy of the atlas experiment and a set of dedicated triggers was contributing to the event selection for the 2011 running. the b - jets acceptance is increased and the background reduced by lowering jet transverse energy thresholds at the first trigger level and applying b - tagging techniques at the subsequent levels. different physics channels, especially topologies containing more than one b - jet where higher rejection factors are achieved, benefit from using the b - jet trigger. an overview of the b - jet trigger menu and performance on data is presented.
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arxiv:1111.4190
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persistent homology is a powerful tool in topological data analysis ( tda ) to capture topological properties of data succinctly at different spatial resolutions. for graphical data, shape, and structure of the neighborhood of individual data items ( nodes ) is an essential means of characterizing their properties. in this paper, we propose the use of persistent homology methods to capture structural and topological properties of graphs and use it to address the problem of link prediction. we evaluate our approach on seven different real - world datasets and offer directions for future work.
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arxiv:1811.04049
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we give a fully polynomial - time approximation scheme ( fptas ) to count the number of independent sets on almost every $ \ delta $ - regular bipartite graph if $ \ delta \ ge 53 $. in the weighted case, for all sufficiently large integers $ \ delta $ and weight parameters $ \ lambda = \ tilde \ omega \ left ( \ frac { 1 } { \ delta } \ right ) $, we also obtain an fptas on almost every $ \ delta $ - regular bipartite graph. our technique is based on the recent work of jenssen, keevash and perkins ( soda, 2019 ) and we also apply it to confirm an open question raised there : for all $ q \ ge 3 $ and sufficiently large integers $ \ delta = \ delta ( q ) $, there is an fptas to count the number of $ q $ - colorings on almost every $ \ delta $ - regular bipartite graph.
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arxiv:1903.07531
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we elaborate the frame dependence of the angular conditions for spin - 1 form factors. an extra angular condition is found in addition to the usual angular condition relating the four helicity amplitudes. investigating the frame - dependence of the angular conditions, we find that the extra angular condition is in general as complicated as the usual one, although it becomes very simple in the $ q ^ + = 0 $ frame involving only two helicity amplitudes. it is confirmed that the angular conditions are identical in frames that are connected by kinematical transformations. the high $ q ^ 2 $ behaviors of the physical form factors and the limiting behaviors in special reference frames are also discussed.
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arxiv:hep-ph/0109005
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the electronic energy structures and magnetic properties of layered superconductors $ r $ ni $ _ 2 $ b $ _ 2 $ c, $ r $ fe $ _ 4 $ al $ _ 8 $ and fese are systematically studied, by using the density functional theory ( dft ). the calculations allowed us to reveal a number of features of the electronic structure, which can cause the manifestation of peculiar structural, magnetic and superconducting properties of these systems. it is demonstrated that the fermi energy $ e _ { \ rm f } $ is located close to the pronounced peaks of the electronic density of states ( dos ). the main contribution to dos at the fermi level arises from $ 3d $ - electrons. the calculations of the pressure - dependent electronic structure and the magnetic susceptibility in the normal state indicate that the novel superconductors are very close to a magnetic instability with dominating spin paramagnetism. it is shown that experimental data on the pressure dependence of the superconducting transition temperature in fese correlate qualitatively with the calculated behavior of dos at $ e _ { \ rm f } $ as a function of the pressure.
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arxiv:1404.0797
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in this paper, we consider a real - world scenario where a model that is trained on pre - defined classes continually encounters unlabeled data that contains both known and novel classes. the goal is to continually discover novel classes while maintaining the performance in known classes. we name the setting continual generalized category discovery ( c - gcd ). existing methods for novel class discovery cannot directly handle the c - gcd setting due to some unrealistic assumptions, such as the unlabeled data only containing novel classes. furthermore, they fail to discover novel classes in a continual fashion. in this work, we lift all these assumptions and propose an approach, called metagcd, to learn how to incrementally discover with less forgetting. our proposed method uses a meta - learning framework and leverages the offline labeled data to simulate the testing incremental learning process. a meta - objective is defined to revolve around two conflicting learning objectives to achieve novel class discovery without forgetting. furthermore, a soft neighborhood - based contrastive network is proposed to discriminate uncorrelated images while attracting correlated images. we build strong baselines and conduct extensive experiments on three widely used benchmarks to demonstrate the superiority of our method.
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arxiv:2308.11063
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let k be a compact semi - simple lie group. we classify k - invariant kaehler structures on the space kc / ( p, p ), where kc is the complexification of k, p is a parabolic subgroup of kc, and ( p, p ) the commutator subgroup. for each kaehler structure, we study its moment map and associated pre - quantum line bundle for geometric quantization. some holomorphic sections of the line bundle form a unitary k - representation space, and we study the multiplicity of its irreducible subrepresentations.
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arxiv:dg-ga/9608008
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in the magnetar model, the quiescent non - thermal soft x - ray emission from anomalous x - ray pulsars and soft - gamma repeaters is thought to arise from resonant comptonization of thermal photons by charges moving in a twisted magnetosphere. robust inference of physical quantities from observations is difficult, because the process depends strongly on geometry and current understanding of the magnetosphere is not very deep. the polarization of soft x - ray photons is an independent source of information, and its magnetospheric imprint remains only partially explored. in this paper we calculate how resonant cyclotron scattering would modify the observed polarization signal relative to the surface emission, using a multidimensional monte carlo radiative transfer code that accounts for the gradual coupling of polarization eigenmodes as photons leave the magnetosphere. we employ a globally - twisted, self - similar, force - free magnetosphere with a power - law momentum distribution, assume a blackbody spectrum for the seed photons, account for general relativistic light deflection close to the star, and assume that vacuum polarization dominates the dielectric properties of the magnetosphere. the latter is a good approximation if the pair multiplicity is not much larger than unity. phase - averaged polarimetry is able to provide a clear signature of the magnetospheric reprocessing of thermal photons and to constrain mechanisms generating the thermal emission. phase - resolved polarimetry, in addition, can characterize the spatial extent and magnitude of the magnetospheric twist angle at ~ 100 stellar radii, and discern between uni - or bidirectional particle energy distributions, almost independently of every other parameter in the system. we discuss prospects for detectability with gems.
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arxiv:1101.0834
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we show a necessary and sufficient condition for any ordinal number to be a polish space. we also prove that for each countable polish space, there exists a countable ordinal number that is an upper bound for the first component of the cantor - bendixson characteristic of every compact countable subset of the aforementioned space. in addition, for any uncountable polish space, for every countable ordinal number and for all nonzero natural number, we show the existence of a compact countable subset of this space such that its cantor - bendixson characteristic equals the previous pair of numbers. finally, for each polish space, we determine the cardinality of the partition, up to homeomorphisms, of the set of all compact countable subsets of the aforesaid space.
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arxiv:2003.01512
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we briefly discuss the physics motivation for a neutrino factory with varying baseline distances of about 1000 to 9000 km. we describe the amount of non planarity of the storage ring required to service three or four detectors at once. a novel bowtie storage ring is described that could in part provide these beams ; a preliminary lattice design is given. we give the space angles between the various detector locations and possible sites for neutrino factories. finally we describe detectors at the gran sasso laboratory and at a new laboratory near carlsbad, nm to observe the neutrino interactions with wrong sign leptons.
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arxiv:hep-ex/0004020
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we present preliminary results from dp - - > 3he x ( x = pi0, eta ) measurements near the eta production threshold. the data were taken during a slow ramping of the cosy internal deuteron beam scattered on a proton target. the 3he ejectiles were registered with the cosy - 11 detection setup. the ongoing data analysis should deliver high precision data for the dp - - > 3he eta total and differential cross sections for the excess energies in the range from threshold up to 9 mev. the preliminary excitation function for the reaction dp - - > 3he pi0 does not show any structure which could originate from the decay of 3he - eta bound state. we present also a threshold excitation curve for the dp - - > 3he x channel. contrary to corresponding results from saturne we see no cusp in the vicinity of the eta threshold.
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arxiv:nucl-ex/0603023
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an optical photometric observation with the batc multicolor system is carried out for the central 56 ' x 56 ' region of the nearby cluster of galaxies, abell 2634. we achieved the spectral energy distributions ( seds ) of 5572 sources detected down to $ v \ sim 20 $ mag, including 178 previously known galaxies, with fourteen filters covering a wavelength range from 3600 \ aa \ to 10000 \ aa. after excluding the foreground and background galaxies, a sample of 124 known members is formed for an investigation of the sed properties. based on the knowledge of sed properties of member galaxies, we performed the selection of faint galaxies belonging to abell 2634. the color - color diagrams are powerful in the star / galaxy separation, and 359 faint galaxies are selected by their color features. the technique of photometric redshift and color - magnitude correlation for the early - type galaxies are applied for these faint galaxies, and a list of 74 faint member galaxies is achieved. basis on the enlarged sample of member galaxies, the spatial distribution and color - magnitude relation of the galaxies in core region of abell 2634 are discussed. we find a tendency that the color index dispersion of the early - type members is larger for the outer region, which might reflect some clues about the environmental effect on the evolution of galaxies in a cluster.
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arxiv:astro-ph/0201272
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very - long - baseline interferometry can image the parsec - scale structure of radio jets, but the accretion disk close to the black hole remains invisible. one way to probe this accretion flow is provided by x - ray flux density monitoring and spectroscopy. here we report on preliminary results of a multi - band campaign on ngc1052 with the goal of combining both approaches to access to the innermost regions of this active galaxy and to establish a connection between the relativistic jets and the accretion region.
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arxiv:astro-ph/0608424
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in this paper we study the controllability of fractional neutral stochastic functional differential equations with infinite delay driven by fractional brownian motion in a real separable hilbert space. the controllability results are obtained by using stochastic analysis and a fixed - point strategy. finally, an illustrative example is provided to demonstrate the effectiveness of the theoretical result.
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arxiv:1604.04079
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we propose a scotogenic model for generating neutrino masses through a three - loop seesaw. it is a minimally extended inert doublet model with a spontaneously broken global symmetry $ u ( 1 ) ' $ and a preserved $ \ mathbb { z } _ 2 $ symmetry. the three - loop suppression allows the new particles to have masses at the tev scale without fine - tuning the yukawa couplings. the model leads to a rich phenomenology while satisfying all the current constraints imposed by neutrinoless double - beta decay, charged - lepton flavor violation, and electroweak precision observables. the relatively large yukawa couplings lead to sizable rates for charged lepton flavor violation processes, well within future experimental reach. the model could also successfully explain the $ w $ mass anomaly and provides viable fermionic or scalar dark matter candidates.
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arxiv:2212.06852
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here we develop an option pricing method based on legendre series expansion of the density function. the key insight, relying on the close relation of the characteristic function with the series coefficients, allows to recover the density function rapidly and accurately. based on this representation for the density function, approximations formulas for pricing european type options are derived. to obtain highly accurate result for european call option, the implementation involves integrating high degree legendre polynomials against exponential function. some numerical instabilities arise because of serious subtractive cancellations in its formulation ( 96 ) in proposition 7. 1. to overcome this difficulty, we rewrite this quantity as solution of a second - order linear difference equation and solve it using a robust and stable algorithm from olver. derivation of the pricing method has been accompanied by an error analysis. errors bounds have been derived and the study relies more on smoothness properties which are not provided by the payoff? functions, but rather by the density function of the underlying stochastic models. this is particularly relevant for options pricing where the payoff of the contract are generally not smooth functions. the numerical experiments on a class of models widely used in quantitative finance show exponential convergence.
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arxiv:1610.03086
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in this paper, the main aim is to demonstrate the boundedness for commutators of ( fractional ) maximal function and sharp maximal function in the slice spaces, where the symbols of the commutators belong to the bmo space, whereby some new characterizations for bmo spaces are given.
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arxiv:2409.14387
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we quantify the important effect of strong final state interactions in the weak $ k \ to 2 \ pi $ amplitudes, using the measured $ \ pi $ - $ \ pi $ phase shifts with j = 0 and $ i = 0, 2 $. the main results of this analysis, with their implications for $ \ epsilon ' / \ epsilon $ and the $ \ delta i = 1 / 2 $ rule, have been already presented in a previous paper [ 1 ]. here we provide a detailed formal derivation of those results and further discuss the standard model prediction of $ \ epsilon ' / \ epsilon $.
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arxiv:hep-ph/0007208
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the original model of axion natural inflation produces a tensor - to - scalar ratio above the experimental limit. aligned axion inflation admits inflationary trajectories that originate near a saddle point of the two - field potential, and terminate due to the instability of the orthogonal direction. the phenomenology of these solutions is within the current constraints, and a range of parameters will be probed by the next stage cmb experiments. we provide the analytic solution for these trajectories and very compact analytic expressions for the associated phenomenology. for parameters leading to the observed value for the scalar spectral tilt the extension of the inflationary trajectory is sub - planckian. however, one eigenvalue of the axion kinetic matrix ( in the basis that diagonalizes the potential ) is trans - planckian. finally, we discuss the post - inflationary evolution after the instability. in some cases, the fields reach a second inflationary valley, connected to a minimum. multiple stages of inflation might be a more general occurrence in multiple - field inflationary models with trajectories starting next to critical points.
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arxiv:2409.01126
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metrology. the institute of instrument science and technology the institute of instrument science and technology is the most important institute in the state key laboratory of precision measuring technology and instrument science at tsinghua university. the institute is equipped with advanced instruments and facilities, and its research has included every major area in modern instrument science and technology. up to 2012, the institute have produced over 1500 publications, more than 100 patents, and acquired many significant awards. the engineering research center for navigation technology the engineering research center for navigation technology is a relatively young institute in the department of precision instrument which was established in 2000, with the intention to " [ pursue ] excellence in the research and development in the field of high - accuracy inertial instruments and navigation technology, as well as in mems inertial sensor fields, and to provide advanced training for future scientists and engineers in the field of inertial technology. " its research interests cover high - accuracy inertial instruments and navigation technology, mems inertial sensors and systems, and precise electro - mechanical control systems and their application. as of 2012, the area of the center is 2900 square meters, including approximately 550 square meters of clean rooms. equipment and instruments in this center are worth over 50 million rmb ( us $ 7. 56 million ). the center for photonics and electronics the center for photonics and electronics works on advanced laser and photonic technology. it houses 200 square meters of clean rooms and very modern laser instruments and equipment. the research of this center covers solid - state laser technology, fiber laser technology, active optics technology, and laser detection technology. the center has published more than published more than 100 scientific papers including 40 indexed by sci, has 18 national patents, and also frequently exchange visits and academic conferences with foreign scholars. the sklt has one central laboratory and four sub - laboratories. it has been awarded numerous awards, including " two national natural science awards, two national invention awards, one national award for science and technology progress, two national excellent science book awards, 25 awards from ministries or provinces of china, edmond e. bisson award in 2003 from stle, the 2008 pe publishing prize by the editor and editorial board of the journal of engineering tribology. " moreover, china ' s ministry of education recognized the sklt as one of the creative groups in 2005, and the national natural science foundation of china recognized the sklt as one of the creative research groups in 2007. the tribology science fund of the key laboratory of tribology cooperates with national
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https://en.wikipedia.org/wiki/Tsinghua_University
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speak of the support of a measure in the same way. suppose that f { \ displaystyle f } is a distribution, and that u { \ displaystyle u } is an open set in euclidean space such that, for all test functions { \ displaystyle \ phi } such that the support of { \ displaystyle \ phi } is contained in u, { \ displaystyle u, } f ( ) = 0. { \ displaystyle f ( \ phi ) = 0. } then f { \ displaystyle f } is said to vanish on u. { \ displaystyle u. } now, if f { \ displaystyle f } vanishes on an arbitrary family u α { \ displaystyle u _ { \ alpha } } of open sets, then for any test function { \ displaystyle \ phi } supported in u α, { \ textstyle \ bigcup u _ { \ alpha }, } a simple argument based on the compactness of the support of { \ displaystyle \ phi } and a partition of unity shows that f ( ) = 0 { \ displaystyle f ( \ phi ) = 0 } as well. hence we can define the support of f { \ displaystyle f } as the complement of the largest open set on which f { \ displaystyle f } vanishes. for example, the support of the dirac delta is { 0 }. { \ displaystyle \ { 0 \ }. } = = singular support = = in fourier analysis in particular, it is interesting to study the singular support of a distribution. this has the intuitive interpretation as the set of points at which a distribution fails to be a smooth function. for example, the fourier transform of the heaviside step function can, up to constant factors, be considered to be 1 / x { \ displaystyle 1 / x } ( a function ) except at x = 0. { \ displaystyle x = 0. } while x = 0 { \ displaystyle x = 0 } is clearly a special point, it is more precise to say that the transform of the distribution has singular support { 0 } { \ displaystyle \ { 0 \ } } : it cannot accurately be expressed as a function in relation to test functions with support including 0. { \ displaystyle 0. } it can be expressed as an application of a cauchy principal value improper integral. for distributions in several variables, singular supports allow one to define wave front sets and understand huygens ' principle in terms of mathematical
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https://en.wikipedia.org/wiki/Support_(mathematics)
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in the spirit of historic astronomical endeavors, we invited school groups across the globe to collaborate in a solar distance measurement using the rare june 5 / 6th transit of venus. in total, we recruited 19 school groups spread over 6 continents and 10 countries to participate in our hetu ' u global network. applying the methods of french astronomer joseph - nicolas delisle, we used individual second and third venus - sun contact times to calculate the distance to the sun. ten of the sites in our network had amiable weather ; 8 of which measured second contact and 5 of which measured third contact leading to consistent solar distance measurements of 152 + / - 30 million km and 163 + / - 30 million km respectively. the distance to the sun at the time of the transit was 152. 25 million km ; therefore, our measurements are also consistent within 1sigma of the known value. the goal of our international school group network was to inspire the next generation of scientists using the excitement and accessibility of a rare astronomical event. in the process, we connected hundreds of participating students representing a diverse, multi - cultural group with differing political, economic, and racial backgrounds.
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arxiv:1210.0873
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recently, several approaches for multiscale simulations for problems with high contrast and no scale separation are introduced. among them is the nonlocal multicontinua ( nlmc ) method, which introduces multiple macroscopic variables in each computational grid. these approaches explore the entire coarse block resolution and one can obtain optimal convergence results independent of contrast and scales. however, these approaches are not amenable to many multiscale simulations, where the subgrid effects are much smaller than the coarse - mesh resolution. for example, the molecular dynamics of shale gas occurs in much smaller length scales compared to the coarse - mesh size, which is of orders of meters. in this case, one can not explore the entire coarse - grid resolution in evaluating effective properties. in this paper, we merge the concepts of nonlocal multicontinua methods and representative volume element ( rve ) concepts to explore problems with extreme scale separation. the first step of this approach is to use sub - grid scale ( sub to rve ) to write a large - scale macroscopic system. we call it intermediate scale macroscale system. in the next step, we couple this intermediate macroscale system to the simulation grid model, which are used in simulations. this is done using rve concepts, where we relate intermediate macroscale variables to the macroscale variables defined on our simulation coarse grid. our intermediate coarse model allows formulating macroscale variables correctly and coupling them to the simulation grid. we present the general concept of our approach and present details of single - phase flow. some numerical results are presented. for nonlinear examples, we use machine learning techniques to compute macroscale parameters.
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arxiv:2001.07988
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roman urdu is an informal form of the urdu language written in roman script, which is widely used in south asia for online textual content. it lacks standard spelling and hence poses several normalization challenges during automatic language processing. in this article, we present a feature - based clustering framework for the lexical normalization of roman urdu corpora, which includes a phonetic algorithm urduphone, a string matching component, a feature - based similarity function, and a clustering algorithm lex - var. urduphone encodes roman urdu strings to their pronunciation - based representations. the string matching component handles character - level variations that occur when writing urdu using roman script.
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arxiv:2004.00088
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food technology is a branch of food science that addresses the production, preservation, quality control and research and development of food products. it may also be understood as the science of ensuring that a society is food secure and has access to safe food that meets quality standards. early scientific research into food technology concentrated on food preservation. nicolas appert ' s development in 1810 of the canning process was a decisive event. the process wasn ' t called canning then and appert did not really know the principle on which his process worked, but canning has had a major impact on food preservation techniques. louis pasteur ' s research on the spoilage of wine and his description of how to avoid spoilage in 1864, was an early attempt to apply scientific knowledge to food handling. besides research into wine spoilage, pasteur researched the production of alcohol, vinegar, wines and beer, and the souring of milk. he developed pasteurization – the process of heating milk and milk products to destroy food spoilage and disease - producing organisms. in his research into food technology, pasteur became the pioneer into bacteriology and of modern preventive medicine. = = developments = = developments in food technology have contributed greatly to the food supply and have changed our world. some of these developments are : instantized milk powder – instant milk powder has become the basis for a variety of new products that are rehydratable. this process increases the surface area of the powdered product by partially rehydrating spray - dried milk powder. freeze - drying – the first application of freeze drying was most likely in the pharmaceutical industry ; however, a successful large - scale industrial application of the process was the development of continuous freeze drying of coffee. high - temperature short time processing – these processes, for the most part, are characterized by rapid heating and cooling, holding for a short time at a relatively high temperature and filling aseptically into sterile containers. decaffeination of coffee and tea – decaffeinated coffee and tea was first developed on a commercial basis in europe around 1900. the process is described in u. s. patent 897, 763. green coffee beans are treated with water, heat and solvents to remove the caffeine from the beans. process optimization – food technology now allows production of foods to be more efficient, oil saving technologies are now available on different forms. production methods and methodology have also become increasingly sophisticated. aseptic packaging – the process of filling a commercially sterile product into a sterile container and hermetically sealing the containers so that
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https://en.wikipedia.org/wiki/Food_technology
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the local galaxy bias formalism relies on the energy constraint equation at the formation time to relate the metric perturbation to the matter density contrast. in the newtonian approximation, this relationship is linear, which allows us to specify the initial galaxy density as a function of local physical operators. in general relativity however, the relationship is intrinsically nonlinear and a modulation of the short - wavelength mode by the long - wavelength mode might be expected. we describe in detail how to obtain local coordinates where the coupling of the long - to the short - wavelength modes is removed through a change of coordinates ( in the absence of the primordial non - gaussianity ). we derive the general - relativistic correction to the galaxy bias expansion at second order. the correction does not come from the modulation of small - scale clustering by the long - wavelength mode ; instead, it arises from distortions of the volume element by the long - wavelength mode and it does not lead to new bias parameters.
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arxiv:1901.07460
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relational arrays represent measures of association between pairs of actors, often in varied contexts or over time. trade flows between countries, financial transactions between individuals, contact frequencies between school children in classrooms, and dynamic protein - protein interactions are all examples of relational arrays. elements of a relational array are often modeled as a linear function of observable covariates. uncertainty estimates for regression coefficient estimators - - and ideally the coefficient estimators themselves - - must account for dependence between elements of the array ( e. g. relations involving the same actor ) and existing estimators of standard errors that recognize such relational dependence rely on estimating extremely complex, heterogeneous structure across actors. this paper develops a new class of parsimonious coefficient and standard error estimators for regressions of relational arrays. we leverage an exchangeability assumption to derive standard error estimators that pool information across actors and are substantially more accurate than existing estimators in a variety of settings. this exchangeability assumption is pervasive in network and array models in the statistics literature, but not previously considered when adjusting for dependence in a regression setting with relational data. we demonstrate improvements in inference theoretically, via a simulation study, and by analysis of a data set involving international trade.
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arxiv:1701.05530
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with the development of information technology and the internet, recommendation systems have become an important means to solve the problem of information overload. however, recommendation system is greatly fragile as it relies heavily on behavior data of users, which makes it very easy for a host of malicious merchants to inject shilling attacks in order to manipulate the recommendation results. some papers on shilling attack have proposed the detection methods, whether based on false user profiles or abnormal items, but their detection rate, false alarm rate, universality, and time overhead need to be further improved. in this paper, we propose a new item anomaly detection method, through t - distribution technology based on dynamic time intervals. first of all, based on the characteristics of shilling attack quickness ( attackers inject a large number of fake profiles in a short period in order to save costs ), we use dynamic time interval method to divide the rating history of item into multiple time windows. then, we use the t - distribution to detect the exception windows. by conducting extensive experiments on a dataset that accords with real - life situations and comparing it to currently outstanding methods, our proposed approach has a higher detection rate, lower false alarm rate and smaller time overhead to the different attack models and filler sizes.
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arxiv:1908.06967
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technology to modulate the apparent slipperiness of a glass touchscreen. in 2013, apple inc. was awarded the patent for a haptic feedback system that is suitable for multitouch surfaces. apple ' s u. s. patent for a " method and apparatus for localization of haptic feedback " describes a system where at least two actuators are positioned beneath a multitouch input device, providing vibratory feedback when a user makes contact with the unit. specifically, the patent provides for one actuator to induce a feedback vibration, while at least one other actuator uses its vibrations to localize the haptic experience by preventing the first set of vibrations from propagating to other areas of the device. the patent gives the example of a " virtual keyboard, " however, it is also noted that the invention can be applied to any multitouch interface. apple ' s iphones ( and macbooks ) featuring the " taptic engine ", accomplish their vibrations with a linear resonant actuator ( lra ), which moves a mass in a reciprocal manner by means of a magnetic voice coil, similar to how ac electrical signals are translated into motion in the cone of a loudspeaker. lras are capable of quicker response times than erms, and thus can transmit more accurate haptic imagery. = = = = virtual reality = = = = haptics are gaining widespread acceptance as a key part of virtual reality systems, adding the sense of touch to previously visual - only interfaces. systems are being developed to use haptic interfaces for 3d modeling and design, including systems that allow holograms to be both seen and felt. several companies are making full - body or torso haptic vests or haptic suits for use in immersive virtual reality to allow users to feel explosions and bullet impacts. = = = = personal computers = = = = in 2015, apple inc. ' s macbook and macbook pro started incorporating a " tactile touchpad " design with button functionality and haptic feedback incorporated into the tracking surface. the tactile touchpad allows for a feeling of " give " when clicking despite the fact that the touchpad no longer moves. = = = sensory substitution = = = = = = = sound substitution = = = = in december 2015 david eagleman demonstrated a wearable vest that " translates " speech and other audio signals into series of vibrations. this allowed hearing - impaired people to " feel " sounds on their body ; it has since been made
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https://en.wikipedia.org/wiki/Haptic_technology
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in this work, we evaluated lithuanian and general history knowledge of multilingual large language models ( llms ) on a multiple - choice question - answering task. the models were tested on a dataset of lithuanian national and general history questions translated into baltic, nordic, and other languages ( english, ukrainian, arabic ) to assess the knowledge sharing from culturally and historically connected groups. we evaluated gpt - 4o, llama3. 1 8b and 70b, qwen2. 5 7b and 72b, mistral nemo 12b, llama3 8b, mistral 7b, llama3. 2 3b, and nordic fine - tuned models ( gpt - sw3 and llama3 8b ). our results show that gpt - 4o consistently outperformed all other models across language groups, with slightly better results for baltic and nordic languages. larger open - source models like qwen2. 5 72b and llama3. 1 70b performed well but showed weaker alignment with baltic languages. smaller models ( mistral nemo 12b, llama3. 2 3b, qwen 7b, llama3. 1 8b, and llama3 8b ) demonstrated gaps with lt - related alignment with baltic languages while performing better on nordic and other languages. the nordic fine - tuned models did not surpass multilingual models, indicating that shared cultural or historical context alone does not guarantee better performance.
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arxiv:2501.09154
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collaborative filtering or recommender systems use a database about user preferences to predict additional topics or products a new user might like. in this paper we describe several algorithms designed for this task, including techniques based on correlation coefficients, vector - based similarity calculations, and statistical bayesian methods. we compare the predictive accuracy of the various methods in a set of representative problem domains. we use two basic classes of evaluation metrics. the first characterizes accuracy over a set of individual predictions in terms of average absolute deviation. the second estimates the utility of a ranked list of suggested items. this metric uses an estimate of the probability that a user will see a recommendation in an ordered list. experiments were run for datasets associated with 3 application areas, 4 experimental protocols, and the 2 evaluation metrics for the various algorithms. results indicate that for a wide range of conditions, bayesian networks with decision trees at each node and correlation methods outperform bayesian - clustering and vector - similarity methods. between correlation and bayesian networks, the preferred method depends on the nature of the dataset, nature of the application ( ranked versus one - by - one presentation ), and the availability of votes with which to make predictions. other considerations include the size of database, speed of predictions, and learning time.
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arxiv:1301.7363
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we present a theoretical study of the electronic structures of freestanding nanowires made from gallium phosphide ( gap ) - - a iii - v semiconductor with an indirect bulk bandgap. we consider [ 001 ] - oriented gap nanowires with square and rectangular cross sections, and [ 111 ] - oriented gap nanowires with hexagonal cross sections. based on tight binding models, both the band structures and wave functions of the nanowires are calculated. for the [ 001 ] - oriented gap nanowires, the bands show anti - crossing structures, while the bands of the [ 111 ] - oriented nanowires display crossing structures. two minima are observed in the conduction bands, while the maximum of the valence bands is always at the $ \ gamma $ - point. using double group theory, we analyze the symmetry properties of the lowest conduction band states and highest valence band states of gap nanowires with different sizes and directions. the band state wave functions of the lowest conduction bands and the highest valence bands of the nanowires are evaluated by spatial probability distributions. for practical use, we fit the confinement energies of the electrons and holes in the nanowires to obtain an empirical formula.
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arxiv:1606.02636
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in the context of his theory of numberings, ershov showed that kleene ' s recursion theorem holds for any precomplete numbering. we discuss various generalizations of this result. among other things, we show that arslanov ' s completeness criterion also holds for every precomplete numbering, and we discuss the relation with visser ' s adn theorem, as well as the uniformity or nonuniformity of the various fixed point theorems. finally, we base numberings on partial combinatory algebras and prove a generalization of ershov ' s theorem in this context.
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arxiv:1809.06233
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in fast wave current drive, the resonant electron is accelerated by fast wave in the direction parallel to the static magnetic field, and the parallel velocity will be increased. the trajectories of the trapped resonant electrons are calculated with a computer code in which fast wave - induced diffusion in velocity space is accounted for by a quasi - linear operator. the simulation results show that the orbit of trapped resonant electron will change from a trapped orbit to a passing orbit in some cases. we obtain the transition conditions, and if they are satisfied the trapped orbit will become a passing orbit. the transition from trapped orbit to passing orbit implies that the effect of trapped electrons on current drive will be reduced and the current drive efficiency will be improved.
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arxiv:1003.5719
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automatic structures are finitely presented structures where the universe and all relations can be recognized by finite automata. it is known that the isomorphism problem for automatic structures is complete for $ \ sigma ^ 1 _ 1 $ ; the first existential level of the analytical hierarchy. several new results on isomorphism problems for automatic structures are shown in this paper : ( i ) the isomorphism problem for automatic equivalence relations is complete for $ \ pi ^ 0 _ 1 $ ( first universal level of the arithmetical hierarchy ). ( ii ) the isomorphism problem for automatic trees of height $ n \ geq 2 $ is $ \ pi ^ 0 _ { 2n - 3 } $ - complete. ( iii ) the isomorphism problem for automatic linear orders is not arithmetical. this solves some open questions of khoussainov, rubin, and stephan.
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arxiv:1001.2086
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we consider a system of non - interacting brownian particles on the line with steplike initial condition and study the statistics of the occupation time on the positive half - line. we demonstrate that this system exhibits long - lasting memory effects of the initialization. specifically, we calculate the mean and the variance of the occupation time, demonstrating that the memory effects in the variance are determined by a generalized compressibility ( or fano factor ), associated with the initial condition. in the particular case of the uncorrelated uniform initial condition we conduct a detailed study of two probability distributions of the occupation time : annealed ( averaged over all possible initial configurations ) and quenched ( for a typical configuration ). we show that at large times both the annealed and the quenched distributions admit large deviation form and we compute analytically the associated rate functions. we verify our analytical predictions via numerical simulations using importance sampling monte - carlo strategy.
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arxiv:2311.17689
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this work determines the inaccuracy of using reynolds averaged navier stokes ( rans ) turbulence models in transition to turbulent flow regimes by predicting the model - based discrepancies between rans and large eddy simulation ( les ) models and then incorporates the capabilities of machine learning algorithms to characterize the discrepancies which are defined as a function of mean flow properties of rans simulations. first, three - dimensional cfd simulations using k - omega shear stress transport ( sst ) and dynamic one - equation subgrid - scale models are conducted in a wall - bounded channel containing a cylinder for rans and les, respectively, to identify the turbulent kinetic energy discrepancy. second, several flow features such as viscosity ratio, wall - distance based reynolds number, and vortex stretching are calculated from the mean flow properties of rans. then these flow features are regressed onto the discrepancy using a random forests regression algorithm. finally, the discrepancy of the test flow is predicted using the trained algorithm. the results reveal that a significant discrepancy exists between rans and les simulations and ml algorithm successfully predicts the increased model uncertainties caused by the employment of k - omega sst turbulence model for transitional fluid flows.
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arxiv:1807.05605
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the resonance mechanism in the initial stage of wind - wave generation proposed by phillips ( j. fluid mech., vol. 2, 1957, 417 $ \ unicode { x2013 } $ 445 ) is a foundation of wind - wave generation theory, but a precise theoretical quantification of wave energy growth in this initial stage has not been obtained yet after more than six decades of research. in this study, we aim to address this knowledge gap by developing an analytical approach based on a novel complex analysis method to theoretically investigate the temporal evolution of the wave energy in the phillips initial stage. we quantitatively derive and analyse the growth behaviour of the surface wave energy and obtain an analytical solution for its upper bound. our result highlights the crucial effects of surface tension. because the phase velocity of gravity $ \ unicode { x2013 } $ capillary waves has a minimal value at a critical wavenumber, gravity $ \ unicode { x2013 } $ capillary waves and gravity waves ( which neglect surface tension ) exhibit distinct resonance curve properties and wave energy growth behaviours. for gravity waves, the resonance curve extends indefinitely ; for gravity $ \ unicode { x2013 } $ capillary waves, it either forms a finite - length curve or does not exist, depending on the wind speed. the leading - order term of the upper - bound solution of the energy of gravity waves increases linearly over time, while for gravity $ \ unicode { x2013 } $ capillary waves, the term increases linearly over time under strong wind conditions but remains finite under weak wind conditions. this theoretical study provides an analytical framework for the generation of wind - waves in the phillips initial stage, which may inspire further theoretical, numerical, and experimental research.
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arxiv:2412.20352
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we study $ 4 $ - dimensional $ su ( n ) \ times u ( 1 ) $ gauge theories with a single massless dirac fermion in the $ 2 $ - index symmetric / antisymmetric representations and show that they are endowed with a noninvertible $ 0 $ - form $ \ widetilde { \ mathbb z } _ { 2 ( n \ pm 2 ) } ^ { \ chi } $ chiral symmetry along with a $ 1 $ - form $ \ mathbb z _ n ^ { ( 1 ) } $ center symmetry. by using the hamiltonian formalism and putting the theory on a spatial three - torus $ \ mathbb t ^ 3 $, we construct the non - unitary gauge invariant operator corresponding to $ \ widetilde { \ mathbb z } _ { 2 ( n \ pm 2 ) } ^ { \ chi } $ and find that it acts nontrivially in sectors of the hilbert space characterized by selected magnetic fluxes. when we subject $ \ mathbb t ^ 3 $ to $ \ mathbb z _ n ^ { ( 1 ) } $ twists, for $ n $ even, in selected magnetic flux sectors, the algebra of $ \ widetilde { \ mathbb z } _ { 2 ( n \ pm 2 ) } ^ { \ chi } $ and $ \ mathbb z _ n ^ { ( 1 ) } $ fails to commute by a $ \ mathbb z _ 2 $ phase. we interpret this noncommutativity as a mixed anomaly between the noninvertible and the $ 1 $ - form symmetries. the anomaly implies that all states in the torus hilbert space with the selected magnetic fluxes exhibit a two - fold degeneracy for arbitrary $ \ mathbb t ^ 3 $ size. the degenerate states are labeled by discrete electric fluxes and are characterized by nonzero expectation values of condensates. in an appendix, we also discuss how to construct the corresponding noninvertible defect via the ` ` half - space gauging ' ' of a discrete one - form magnetic symmetry.
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arxiv:2305.14425
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we study nonlinear properties of multilayer metamaterials created by graphene sheets separated by dielectric layers. we demonstrate that such structures can support localized nonlinear modes described by the discrete nonlinear schr \ " { o } dinger equation and that its solutions are associated with stable discrete plasmon solitons. we also analyze the nonlinear surface modes in truncated graphene metamaterials being a nonlinear analog of surface tamm states.
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arxiv:1410.4823
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we discuss three topics : ( i ) the dynamics of afterglow jet breaks ; ( ii ) the origin of fermi - lat photons ; ( iii ) the electromagnetic model of short grbs
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arxiv:1306.5978
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we propose to unify the gravity and standard model gauge groups by using algebraic spinors of the standard four - dimensional clifford algebra, in left - right symmetric fashion. this generates exactly a standard model family of fermions, and a pati - salam unification group emerges, at the planck scale, where ( chiral ) self - dual gravity decouples. as a remnant of the unification, isospin - triplets spin - two particles may naturally appear at the weak scale, providing a striking signal at the lhc.
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arxiv:0706.3304
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chiral molecules are widespread in nature, playing a fundamental role in bio - chemical processes and in the origin of life itself. the observation of dynamics in chiral molecules is crucial for the understanding and control of the chiral activity of photo - excited states. one of the most promising techniques for the study of photo - excited chiral systems is time - resolved photoelectron circular dichroism ( tr - pecd ), which offers an intense and sensitive probe for vibronic and geometric molecular structure as well as electronic structures, and their evolution on a femtosecond timescale. however, the non - local character of the pecd effect, which is imprinted during the electron scattering off the molecule, makes the interpretation of tr - pecd experiments challenging. in this respect, core - photoionization is known to allow site - and chemical - sensitivity to photelectron spectroscopy. here we demonstrate that tr - pecd utilising core - level photoemission enables probing the chiral electronic structure and its relaxation dynamics with atomic site sensitivity. following uv pumped excitation to a 3s rydberg state, fenchone enantiomers ( c 10 h 16 o ) were probed on a femtosecond scale using circularly polarized soft x - ray light pulses provided by the free - electron laser fermi. c 1s binding energy shifts caused by the redistribution of valence electron density in this 3s - valence - rydberg excitation allowed us to measure transient pecd chiral responses with an enhanced c - atom site - selectivity compared to that achievable in the ground state molecule. these results represent the first chemical - specific and site - specific, enantio - sensitive observations on the electronic structure of a photo - excited chiral molecule and pave the way towards chiral femtochemistry probed by core - level photoemission.
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arxiv:2202.13704
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several results are presented for site percolation on quasi - transitive, planar graphs $ g $ with one end, when properly embedded in either the euclidean or hyperbolic plane. if $ ( g _ 1, g _ 2 ) $ is a matching pair derived from some quasi - transitive mosaic $ m $, then $ p _ u ( g _ 1 ) + p _ c ( g _ 2 ) = 1 $, where $ p _ c $ is the critical probability for the existence of an infinite cluster, and $ p _ u $ is the critical value for the existence of a unique such cluster. this fulfils and extends to the hyperbolic plane an observation of sykes and essam ( 1964 ), and it extends to quasi - transitive site models a theorem of benjamini and schramm ( theorem 3. 8, j. amer. math. soc. 14 ( 2001 ) 487 - - 507 ) for transitive bond percolation. it follows that $ p _ u ( g ) + p _ c ( g _ * ) = p _ u ( g _ * ) + p _ c ( g ) = 1 $, where $ g _ * $ denotes the matching graph of $ g $. in particular, $ p _ u ( g ) + p _ c ( g ) \ ge 1 $ and hence, when $ g $ is amenable we have $ p _ c ( g ) = p _ u ( g ) \ ge \ frac12 $. when combined with the main result of the companion paper by the same authors ( " percolation critical probabilities of matching lattice - pairs ", random struct. alg. 2024 ), we obtain for transitive $ g $ that the strict inequality $ p _ u ( g ) + p _ c ( g ) > 1 $ holds if and only if $ g $ is not a triangulation. a key technique is a method for expressing a planar site percolation process on a matching pair in terms of a dependent bond process on the corresponding dual pair of graphs. amongst other things, the results reported here answer positively two conjectures of benjamini and schramm ( conjectures 7 and 8, electron. comm. probab. 1 ( 1996 ) 71 - - 82 ) in the case of quasi - transitive graphs.
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arxiv:2203.00981
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we calculate the exact landau - zener transitions probabilities for a qubit with arbitrary linear coupling to a bath at zero temperature. the final quantum state exhibits a peculiar entanglement between the qubit and the bath. in the special case of a diagonal coupling, the bath does not influence the transition probability, whatever the speed of the landau - zener sweep. it is proposed to use landau - zener transitions to determine both the reorganization energy and the integrated spectral density of the bath. possible applications include circuit qed and molecular nanomagnets.
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arxiv:cond-mat/0608333
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be divided between the formal thinking of officers brought up in the " shadow " of the napoleonic wars and younger officers like ardant du picq who tended to view fighting performance as rooted in the individual ' s and group psychology and suggested detailed analysis of this. this set in motion the eventual fascination of the military organisations with application of quantitative and qualitative research to their theories of combat ; the attempt to translate military thinking as philosophic concepts into concrete methods of combat. military implements, the supply of an army, its organization, tactics, and discipline, have constituted the elements of military science in all ages ; but improvement in weapons and accoutrements appears to lead and control all the rest. the breakthrough of sorts made by clausewitz in suggesting eight principles on which such methods can be based, in europe, for the first time presented an opportunity to largely remove the element of chance and error from command decision making process. at this time emphasis was made on the topography ( including trigonometry ), military art ( military science ), military history, organisation of the army in the field, artillery and the science of projectiles, field fortifications and permanent fortifications, military legislation, military administration and manoeuvres. the military science on which the model of german combat operations was built for the first world war remained largely unaltered from the napoleonic model, but took into the consideration the vast improvements in the firepower and the ability to conduct " great battles of annihilation " through rapid concentration of force, strategic mobility, and the maintenance of the strategic offensive better known as the cult of the offensive. the key to this, and other modes of thinking about war, remained analysis of military history and attempts to derive tangible lessons that could be replicated again with equal success on another battlefield as a sort of bloody laboratory of military science. few were bloodier than the fields of the western front between 1914 and 1918. the person who probably understood clausewitz better than most, marshal foch, initially participated in events that nearly destroyed the french army. it is not, however, true to say that military theorists and commanders were suffering from some collective case of stupidity. their analysis of military history convinced them that decisive and aggressive strategic offensive was the only doctrine of victory, and feared that overemphasis of firepower, and the resultant dependence on entrenchment would make this all but impossible, and leading to the battlefield stagnant in advantages of the defensive position, destroying troop morale and willingness to fight. because only the offensive could bring victory,
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https://en.wikipedia.org/wiki/Military_science
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root9 is a supervised system for the classification of hypernyms, co - hyponyms and random words that is derived from the already introduced root13 ( santus et al., 2016 ). it relies on a random forest algorithm and nine unsupervised corpus - based features. we evaluate it with a 10 - fold cross validation on 9, 600 pairs, equally distributed among the three classes and involving several parts - of - speech ( i. e. adjectives, nouns and verbs ). when all the classes are present, root9 achieves an f1 score of 90. 7 %, against a baseline of 57. 2 % ( vector cosine ). when the classification is binary, root9 achieves the following results against the baseline : hypernyms - co - hyponyms 95. 7 % vs. 69. 8 %, hypernyms - random 91. 8 % vs. 64. 1 % and co - hyponyms - random 97. 8 % vs. 79. 4 %. in order to compare the performance with the state - of - the - art, we have also evaluated root9 in subsets of the weeds et al. ( 2014 ) datasets, proving that it is in fact competitive. finally, we investigated whether the system learns the semantic relation or it simply learns the prototypical hypernyms, as claimed by levy et al. ( 2015 ). the second possibility seems to be the most likely, even though root9 can be trained on negative examples ( i. e., switched hypernyms ) to drastically reduce this bias.
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arxiv:1603.08702
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in this article we summarize and extend the ideas and investigations on so called target space dualities of heterotic models with ( 0, 2 ) worldsheet supersymmetry as they were partly presented on the string - math 2011 conference. after the generic description of the duality, we give some novel examples involving vector bundles that are not deformations of the tangent bundle but more generic ones corresponding to so ( 10 ) and su ( 5 ) gauge theories in four dimensions. we show explicitly that the necessary conditions for a duality also hold for compactifications of this kind. finally we will present the results of the large landscape scan of e _ 6 models.
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arxiv:1111.0491
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in emergency scenarios, unmanned aerial vehicles ( uavs ) can be deployed to assist localization and communication services for ground terminals. in this paper, we propose a new integrated air - ground networking paradigm that uses dual - functional uavs to assist the ground networks for improving both communication and localization performance. we investigate the optimization problem of deploying the minimal number of uavs to satisfy the communication and localization requirements of ground users. the problem has several technical difficulties including the cardinality minimization, the non - convexity of localization performance metric regarding uav location, and the association between user and communication terminal. to tackle the difficulties, we adopt d - optimality as the localization performance metric, and derive the geometric characteristics of the feasible uav hovering regions in 2d and 3d based on accurate approximation values. we solve the simplified 2d projection deployment problem by transforming the problem into a minimum hitting set problem, and propose a low - complexity algorithm to solve it. through numerical simulations, we compare our proposed algorithm with benchmark methods. the number of uavs required by the proposed algorithm is close to the optimal solution, while other benchmark methods require much more uavs to accomplish the same task.
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arxiv:2209.05031
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we perform a general optimization of the parameters in the multilevel monte carlo ( mlmc ) discretization hierarchy based on uniform discretization methods with general approximation orders and computational costs. we optimize hierarchies with geometric and non - geometric sequences of mesh sizes and show that geometric hierarchies, when optimized, are nearly optimal and have the same asymptotic computational complexity as non - geometric optimal hierarchies. we discuss how enforcing constraints on parameters of mlmc hierarchies affects the optimality of these hierarchies. these constraints include an upper and a lower bound on the mesh size or enforcing that the number of samples and the number of discretization elements are integers. we also discuss the optimal tolerance splitting between the bias and the statistical error contributions and its asymptotic behavior. to provide numerical grounds for our theoretical results, we apply these optimized hierarchies together with the continuation mlmc algorithm. the first example considers a three - dimensional elliptic partial differential equation with random inputs. its space discretization is based on continuous piecewise trilinear finite elements and the corresponding linear system is solved by either a direct or an iterative solver. the second example considers a one - dimensional it \ ^ o stochastic differential equation discretized by a milstein scheme.
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arxiv:1403.2480
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transport of molecules across membrane channels is investigated theoretically using exactly solvable one - dimensional discrete - state stochastic models. an interaction between molecules and membrane pores is modeled via a set of binding sites with different energies. it is shown that the interaction potential strongly influences the particle currents as well as fluctuations in the number of translocated molecules. for small concentration gradients the attractive sites lead to largest currents and fluctuations, while the repulsive interactions yield the largest fluxes and dispersions for large concentration gradients. interaction energies that lead to maximal currents and maximal fluctuations are the same only for locally symmetric potentials, while they differ for the locally asymmetric potentials. the conditions for the most optimal translocation transport with maximal current and minimal dispersion are discussed. it is argued that in this case the interaction strength is independent of local symmetry of the potential of mean forces. in addition, the effect of the global asymmetry of the interaction potential is investigated, and it is shown that it also strongly affects the particle translocation dynamics. these phenomena can be explained by analyzing the details of the particle entering and leaving the binding sites in the channel.
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arxiv:0710.4359
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the intersection between security and continuous software engineering has been of great interest since the early years of the agile development movement, and it remains relevant as software development processes are more frequently guided by agility and the adoption of devops. several authors have contributed studies about the framing of secure agile development and secure devops, motivating academic contributions to methods and practices, but also discussions around benefits and challenges. especially the challenges captured also our interest since, for the last few years, we are conducting research on secure continuous software engineering from a more applied, practical perspective with the overarching aim to introduce solutions that can be adopted at scale. the short positioning at hands summarizes a relevant part of our endeavors in which we validated challenges with several practitioners of different roles. more than framing a set of challenges, we conclude by presenting four key research directions we identified for practitioners and researchers to delineate future work.
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arxiv:2401.06529
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mapuzugun is the language of the mapuche people. due to political and historical reasons, its number of speakers has decreased and the language has been excluded from the educational system in chile and argentina. for this reason, it is very important to support the revitalization of the mapuzugun in all spaces and media of society. in this work we present a tool towards supporting educational activities of mapuzugun, tailored to the characteristics of the language. the tool consists of three parts : design and development of an orthography detector and converter ; a morphological analyzer ; and an informal translator. we also present a case study with mapuzugun students showing promising results. short abstract in mapuzuzgun : t \ " ufachi k \ " uzaw pegelfi ki \ ~ ne zugun k \ " uzawpey \ " um kelluaetew pu mapuzugun chillkatufe kimal kizu ta \ ~ ni zugun.
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arxiv:2205.10411
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we report a vlasov simulation of cosmic relic neutrinos combined with n - body simulation of cold dark matter in the context of large - scale structure formation in the universe performed on fugaku supercomputer. gravitational dynamics of the neutrinos is followed, for the first time, by directly integrating the vlasov equation in a six - dimensional phase space. our largest simulation combines the vlasov simulation on 400 trillion grids and 330 billion - body calculations in a self - consistent manner, and reproduces accurately the nonlinear dynamics of neutrinos in the universe. the novel high - order vlasov solver is optimized by combining an array of state - of - the - art numerical schemes and fully utilizing the simd instructions on the a64fx processors. time - to - solution of our simulation is an order of magnitude shorter than the largest n - body simulations. the performance scales excellently with up to 147, 456 nodes ( 7 million cpu cores ) on fugaku ; the weak and strong scaling efficiencies are 82 % - 96 % and 82 % - 93 %, respectively.
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arxiv:2110.15867
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this work proposes a novel data - driven model capable of providing accurate predictions for the power generation of all wind turbines in wind farms of arbitrary layout, yaw angle configurations and wind conditions. the proposed model functions by encoding a wind farm into a fully - connected graph and processing the graph representation through a graph transformer. the graph transformer surrogate is shown to generalise well and is able to uncover latent structural patterns within the graph representation of wind farms. it is demonstrated how the resulting surrogate model can be used to optimise yaw angle configurations using genetic algorithms, achieving similar levels of accuracy to industrially - standard wind farm simulation tools while only taking a fraction of the computational cost.
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arxiv:2311.12750
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we investigate gauge - higgs unification models in eight - dimensional spacetime where extra - dimensional space has the structure of a four - dimensional compact coset space. the combinations of the coset space and the gauge group in the eight - dimensional spacetime of such models are listed. after the dimensional reduction of the coset space, we identified $ \ mathrm { so } ( 10 ) $, $ \ mathrm { so } ( 10 ) \ times \ mathrm { u } ( 1 ) $ and $ \ mathrm { so } ( 10 ) \ times \ mathrm { u } ( 1 ) \ times \ mathrm { u } ( 1 ) $ as the possible gauge groups in the four - dimensional theory that can accomodate the standard model and thus is phenomenologically promising. representations for fermions and scalars for these gauge groups are tabulated.
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arxiv:0903.2164
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we present an inverse method to construct large classes of chaotic invariant sets together with their exact statistics. the associated dynamical systems are characterized by a probability distribution and a two - form. while our emphasis is on classical systems, we briefly speculate about possible applications to quantum field theory, in the context of generalizations of stochastic quantization.
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arxiv:0804.3793
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the coupled exciton - vibrational dynamics of a 3 - site fmo model is investigated using the numerically exact multilayer multiconfiguration time - dependent hartree approach. thereby the vibrational mode specific coupling to local electronic transitions is adapted from a discretized experimental spectral density. the solution of the resulting time - dependent schr \ " odinger equation including three electronic and 450 vibrational degrees of freedom is analyzed in terms of excitonic populations and coherences. emphasis is put onto the role of specific ranges of vibrational frequencies. it is observed that modes between 160 and 300 cm $ ^ { - 1 } $ are responsible for the subpicosecond population and coherence decay. further, it is found that a mean - field approach with respect to the vibrational degrees of freedom is not applicable.
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arxiv:1503.07059
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transformers are transforming the landscape of computer vision, especially for recognition tasks. detection transformers are the first fully end - to - end learning systems for object detection, while vision transformers are the first fully transformer - based architecture for image classification. in this paper, we integrate vision and detection transformers ( vidt ) to build an effective and efficient object detector. vidt introduces a reconfigured attention module to extend the recent swin transformer to be a standalone object detector, followed by a computationally efficient transformer decoder that exploits multi - scale features and auxiliary techniques essential to boost the detection performance without much increase in computational load. extensive evaluation results on the microsoft coco benchmark dataset demonstrate that vidt obtains the best ap and latency trade - off among existing fully transformer - based object detectors, and achieves 49. 2ap owing to its high scalability for large models. we will release the code and trained models at https : / / github. com / naver - ai / vidt
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arxiv:2110.03921
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in this article, we investigate non - trivial topological features in a heterostructure of extreme magnetoresistance ( xmr ) materials laas and labi using density functional theory ( dft ). the proposed heterostructure is found to be dynamically stable and shows bulk band inversion with non - trivial z _ { 2 } topological invariant and a dirac cone at the surface. in addition, its electron and hole carrier densities ratio is also calculated to investigate the possibility to possess xmr effect. electrons and holes in the heterostructure are found to be nearly compensated, thereby facilitating it to be a suitable candidate for xmr studies.
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arxiv:2006.00770
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in this paper, we propose a policy gradient method for confounded partially observable markov decision processes ( pomdps ) with continuous state and observation spaces in the offline setting. we first establish a novel identification result to non - parametrically estimate any history - dependent policy gradient under pomdps using the offline data. the identification enables us to solve a sequence of conditional moment restrictions and adopt the min - max learning procedure with general function approximation for estimating the policy gradient. we then provide a finite - sample non - asymptotic bound for estimating the gradient uniformly over a pre - specified policy class in terms of the sample size, length of horizon, concentratability coefficient and the measure of ill - posedness in solving the conditional moment restrictions. lastly, by deploying the proposed gradient estimation in the gradient ascent algorithm, we show the global convergence of the proposed algorithm in finding the history - dependent optimal policy under some technical conditions. to the best of our knowledge, this is the first work studying the policy gradient method for pomdps under the offline setting.
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arxiv:2305.17083
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one - dimensional anyonic models of the hubbard type show intriguing ground - state properties, effectively transmuting between bose - einstein and fermi - dirac statistics. the simplest model that one can investigate is an anyonic version of the bosonic josephson junction, the repulsive anyon - hubbard dimer. in the following we find an exact duality relation to the bethe - solvable bose - hubbard dimer, which is well known from quantum optics and information theory and has interesting connections to spin squeezing and entangled coherent states. conversely, we show that the anyonic hubbard dimer has nontrivial coherence properties that emerge from the anyonic statistics. in particular, we find that coherences can be suppressed and amplified and show that these features are remarkably robust against additional repulsive on - site interactions highlighting the distinct nature of anyons.
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arxiv:2306.00073
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more than 5 million children under five years die from largely preventable or treatable medical conditions every year, with an overwhelmingly large proportion of deaths occurring in underdeveloped countries with low vaccination uptake. one of the united nations ' sustainable development goals ( sdg 3 ) aims to end preventable deaths of newborns and children under five years of age. we focus on nigeria, where the rate of infant mortality is appalling. in particular, low vaccination uptake in nigeria is a major driver of more than 2, 000 daily deaths of children under the age of five years. in this paper, we describe our collaboration with government partners in nigeria to deploy adviser : ai - driven vaccination intervention optimiser. the framework, based on an integer linear program that seeks to maximize the cumulative probability of successful vaccination, is the first successful deployment of an ai - enabled toolchain for optimizing the allocation of health interventions in nigeria. in this paper, we provide a background of the adviser framework and present results, lessons, and success stories of deploying adviser to more than 13, 000 families in the state of oyo, nigeria.
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arxiv:2402.00017
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in this note, we prove that there is a canonical continuous hermitian metric on the cm line bundle over the proper moduli space $ \ bar { \ mathcal { m } } $ of smoothable kahler - einstein fano varieties. the curvature of this metric is the weil - petersson current, which exists as a positive ( 1, 1 ) - current on $ \ bar { \ mathcal { m } } $ and extends the canonical weil - petersson current on the moduli space parametrizing smooth kahler - einstein fano manifolds $ \ mathcal { m } $. as a consequence, we show that the cm line bundle is nef and big on $ \ bar { \ mathcal { m } } $ and its restriction on $ \ mathcal { m } $ is ample.
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arxiv:1502.06532
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as ai systems become increasingly powerful, the need for safe ai has become more pressing. humans are an attractive model for ai safety : as the only known agents capable of general intelligence, they perform robustly even under conditions that deviate significantly from prior experiences, explore the world safely, understand pragmatics, and can cooperate to meet their intrinsic goals. intelligence, when coupled with cooperation and safety mechanisms, can drive sustained progress and well - being. these properties are a function of the architecture of the brain and the learning algorithms it implements. neuroscience may thus hold important keys to technical ai safety that are currently underexplored and underutilized. in this roadmap, we highlight and critically evaluate several paths toward ai safety inspired by neuroscience : emulating the brain ' s representations, information processing, and architecture ; building robust sensory and motor systems from imitating brain data and bodies ; fine - tuning ai systems on brain data ; advancing interpretability using neuroscience methods ; and scaling up cognitively - inspired architectures. we make several concrete recommendations for how neuroscience can positively impact ai safety.
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arxiv:2411.18526
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we compute analytically the all - loop level critical exponents for a massless thermal lorentz - violating o ( $ n $ ) self - interacting $ \ lambda \ phi ^ { 4 } $ scalar field theory. for that, we evaluate, firstly explicitly up to next - to - leading order and later in a proof by induction up to any loop level, the respective $ \ beta $ - function and anomalous dimensions in a theory renormalized in the massless bphz method, where a reduced set of feynman diagrams to be calculated is needed. we investigate the effect of the lorentz violation in the outcome for the critical exponents and present the corresponding mathematical explanation and physical interpretation.
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arxiv:1503.00896
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audio - driven talking face video generation has attracted increasing attention due to its huge industrial potential. some previous methods focus on learning a direct mapping from audio to visual content. despite progress, they often struggle with the ambiguity of the mapping process, leading to flawed results. an alternative strategy involves facial structural representations ( e. g., facial landmarks ) as intermediaries. this multi - stage approach better preserves the appearance details but suffers from error accumulation due to the independent optimization of different stages. moreover, most previous methods rely on generative adversarial networks, prone to training instability and mode collapse. to address these challenges, our study proposes a novel landmark - based diffusion model for talking face generation, which leverages facial landmarks as intermediate representations while enabling end - to - end optimization. specifically, we first establish the less ambiguous mapping from audio to landmark motion of lip and jaw. then, we introduce an innovative conditioning module called talkformer to align the synthesized motion with the motion represented by landmarks via differentiable cross - attention, which enables end - to - end optimization for improved lip synchronization. besides, talkformer employs implicit feature warping to align the reference image features with the target motion for preserving more appearance details. extensive experiments demonstrate that our approach can synthesize high - fidelity and lip - synced talking face videos, preserving more subject appearance details from the reference image.
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arxiv:2408.05416
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biomolecular condensates in cells are often rich in catalytically - active enzymes. this is particularly true in the case of the large enzymatic complexes known as metabolons, which contain different enzymes that participate in the same catalytic pathway. one possible explanation for this self - organization is the combination of the catalytic activity of the enzymes and a chemotactic response to gradients of their substrate, which leads to a substrate - mediated effective interaction between enzymes. these interactions constitute a purely non - equilibrium effect and show exotic features such as non - reciprocity. here, we analytically study a model describing the phase separation of a mixture of such catalytically - active particles. we show that a michaelis - menten - like dependence of the particles ' activities manifests itself as a screening of the interactions, and that a mixture of two differently - sized active species can exhibit phase separation with transient oscillations. we also derive a rich stability phase diagram for a mixture of two species with both concentration - dependent activity and size dispersity. this work highlights the variety of possible phase separation behaviours in mixtures of chemically - active particles, which provides an alternative pathway to the passive interactions more commonly associated with phase separation in cells. our results highlight non - equilibrium organizing principles that can be important for biologically relevant liquid - liquid phase separation.
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arxiv:2105.02069
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transport phenomena in photosynthetic systems have attracted a great deal of attention due to their potential role in devising novel photovoltaic materials. in particular, energy transport in light - harvesting complexes is considered quite efficient due to the balance between coherent quantum evolution and decoherence, a phenomenon coined environment - assisted quantum transport ( enaqt ). although this effect has been extensively studied, its behavior is typically described in terms of the decoherence ' s strength, namely weak, moderate or strong. here, we study the enaqt in terms of quantum correlations that go beyond entanglement. using a subsystem of the fenna - matthews - olson complex, we find that discord - like correlations maximize when the subsystem ' s transport efficiency increases, while the entanglement between sites vanishes. our results suggest that quantum discord is a manifestation of the enaqt and highlight the importance of beyond - entanglement correlations in photosynthetic energy transport processes.
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arxiv:2104.07717
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this article has been written for an educational magazine whose target audience consists of students and teachers of mathematics in universities, colleges and schools. it concerns a notion of duality between rectangles. a proof is given that only finitely many integral sided pairs of dual rectangles exist. then a geometrical group law is shown to hold on the set of all rational self - dual rectangles. finally, the arithmetic of a cubic surface is used to construct new pairs of rational dual rectangles from old, a technique inspired by the theory of elliptic curves.
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arxiv:0906.3096
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we discuss the design of the muon capture front end for a \ mu + - \ mu - collider. in the front end, a proton bunch on a target creates secondary pions that drift into a capture transport channel, decaying into muons. a sequence of rf cavities forms the resulting muon beams into strings of bunches of differing energies, aligns the bunches to ( nearly ) equal central energies, and initiates ionization cooling. the muons are then cooled and accelerated to high energy into a storage ring for high - energy high luminosity collisions. our initial design is based on the somewhat similar front end of the international design study ( ids ) neutrino factory.
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arxiv:1202.5335
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jets are expected to play a prominent role in the ongoing efforts to characterize the hot and dense qcd medium created in ultrarelativistic heavy ion collisions. the success of this program depends crucially on the existence of a full theoretical account of the dynamical effects of the medium on the jets that develop within it. by focussing on the discussion of the essential ingredients underlying such a theoretical formulation, we aim to set the appropriate context in which current and future developments can be understood.
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arxiv:1302.2579
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renewable sources are taking center stage in electricity generation. due to the intermittent nature of these renewable resources, the problem of the demand - supply gap arises. to solve this problem, several techniques have been proposed in the literature in terms of cost ( adding peaker plants ), availability of data ( demand side management " dsm " ), hardware infrastructure ( appliance controlling dsm ) and safety ( voltage reduction ). however, these solutions are not fair in terms of electricity distribution. in many cases, although the available supply may not match the demand in peak hours, however, the total aggregated demand remains less than the total supply for the whole day. load shedding ( complete blackout ) is a commonly used solution to deal with the demand - supply gap, which can cause substantial economic losses. to solve the demand - supply gap problem, we propose a solution called soft load shedding ( sls ), which assigns electricity quota to each household in a fair way. we measure the fairness of sls by defining a function for household satisfaction level. we model the household utilities by parametric function and formulate the problem of sls as a social welfare problem. we also consider revenue generated from the fair allocation as a performance measure. to evaluate our approach, extensive experiments have been performed on both synthetic and real - world datasets, and our model is compared with several baselines to show its effectiveness in terms of fair allocation and revenue generation.
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arxiv:2002.00451
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we define homology of ternary algebras satisfying axioms derived from particle scattering or, equivalently, from the third reidemeister move. we show that ternary quasigroups satisfying these axioms appear naturally in invariants of reidemeister, yoshikawa, and roseman moves. our homology has a degenerate subcomplex. the normalized homology yields invariants of knots and knotted surfaces.
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arxiv:1706.04307
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many experiments are currently using or proposing to use large area gem foils in their detectors, which is creating a need for commercially available gem foils. currently cern is the only main distributor of large gem foils, however with the growing interest in gem technology keeping up with the increasing demand for gems will be difficult. we present here an update on the assembly and testing of triple - gem tracking detectors utilizing single - masked $ 40 \ times 40 $ cm $ ^ 2 $ commercial gem foils produced by tech - etch. the triple - gem detectors will allow us to characterize the overall quality of these tech - etch foils through gain, efficiency, and energy resolution measurements. this will be done by constructing four single - mask triple - gem detectors, using foils manufactured by tech - etch, which follow the design used by the star forward gem tracker ( fgt ). the stack is formed by gluing the foils to the frames and then gluing the frames together. the stack also includes a tech - etch produced high voltage foil and a 2d $ r - \ phi $ readout foil. while one of the four triple - gem detectors will be built identically to the star fgt, the other three will investigate ways in which to further decrease the material budget and increase the efficiency of the detector by incorporating perforated kapton spacer rings rather than g10 spacing grids to reduce the dead area of the detector.
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arxiv:1806.01892
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increasing the batch size is a popular way to speed up neural network training, but beyond some critical batch size, larger batch sizes yield diminishing returns. in this work, we study how the critical batch size changes based on properties of the optimization algorithm, including acceleration and preconditioning, through two different lenses : large scale experiments, and analysis of a simple noisy quadratic model ( nqm ). we experimentally demonstrate that optimization algorithms that employ preconditioning, specifically adam and k - fac, result in much larger critical batch sizes than stochastic gradient descent with momentum. we also demonstrate that the nqm captures many of the essential features of real neural network training, despite being drastically simpler to work with. the nqm predicts our results with preconditioned optimizers, previous results with accelerated gradient descent, and other results around optimal learning rates and large batch training, making it a useful tool to generate testable predictions about neural network optimization.
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arxiv:1907.04164
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data has exponentially grown in the last years, and knowledge graphs constitute powerful formalisms to integrate a myriad of existing data sources. transformation functions - - specified with function - based mapping languages like funul and rml + fno - - can be applied to overcome interoperability issues across heterogeneous data sources. however, the absence of engines to efficiently execute these mapping languages hinders their global adoption. we propose funmap, an interpreter of function - based mapping languages ; it relies on a set of lossless rewriting rules to push down and materialize the execution of functions in initial steps of knowledge graph creation. although applicable to any function - based mapping language that supports joins between mapping rules, funmap feasibility is shown on rml + fno. funmap reduces data redundancy, e. g., duplicates and unused attributes, and converts rml + fno mappings into a set of equivalent rules executable on rml - compliant engines. we evaluate funmap performance over real - world testbeds from the biomedical domain. the results indicate that funmap reduces the execution time of rml - compliant engines by up to a factor of 18, furnishing, thus, a scalable solution for knowledge graph creation.
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arxiv:2008.13482
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stacking as a tool for studying objects that are not individually detected is becoming popular even for radio interferometric data, and will be widely used in the ska era. stacking is typically done using imaged data rather than directly using the visibilities ( the uv - data ). we have investigated and developed a novel algorithm to do stacking using the uv - data. we have performed exten - sive simulations comparing to image - stacking, and summarize the results of these simulations. furthermore, we disuss the implications in light of the vast data volume produced by the ska. having access to the uv - stacked data provides a great advantage, as it allows the possibility to properly analyse the result with respect to calibration artifacts as well as source properties such as size. for ska the main challenge lies in archiving the uv - data. for purposes of robust stacking analysis, it would be strongly desirable to either keep the calibrated uv - data at least in an aver - age form, or implement a stacking queue where stacking positions could be provided prior to the observations and the uv - stacking is done almost in real time.
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arxiv:1501.05643
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we review recent research on the milky way galaxy and try to investigate whether its shape is similar to other barred galaxies. the emphasis is given on microlensing research because this method can be useful in determining the shape of the galaxy with the minimal set of assumptions. by analyzing plots of the microlensing optical depth, $ \ tau $ as a function of galactic coordinates for different values of the axis ratio, $ q $ of the galactic halo, we have shown that observations are best described by a flattened halo with $ 0. 2 ^ < _ \ sim q ^ < _ \ sim 0. 6 $.
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arxiv:astro-ph/9804223
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magnetic resonance imaging ( mri ) of thigh and calf muscles is one of the most effective techniques for estimating fat infiltration into muscular dystrophies. the infiltration of adipose tissue into the diseased muscle region varies in its severity across, and within, patients. in order to efficiently quantify the infiltration of fat, accurate segmentation of muscle and fat is needed. an estimation of the amount of infiltrated fat is typically done visually by experts. several algorithmic solutions have been proposed for automatic segmentation. while these methods may work well in mild cases, they struggle in moderate and severe cases due to the high variability in the intensity of infiltration, and the tissue ' s heterogeneous nature. to address these challenges, we propose a deep - learning approach, producing robust results with high dice similarity coefficient ( dsc ) of 0. 964, 0. 917 and 0. 933 for muscle - region, healthy muscle and inter - muscular adipose tissue ( imat ) segmentation, respectively.
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arxiv:1910.04866
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the consistently low activity level of the old solar analog 51 peg not only facilitated the discovery of the first hot jupiter, but also led to the suggestion that the star could be experiencing a magnetic grand minimum. however, the 50 year time series showing minimal chromospheric variability could also be associated with the onset of weakened magnetic braking ( wmb ), where sufficiently slow rotation disrupts cycling activity and the production of large - scale magnetic fields by the stellar dynamo, thereby shrinking the alfven radius and inhibiting the efficient loss of angular momentum to magnetized stellar winds. in this letter, we evaluate the magnetic evolutionary state of 51 peg by estimating its wind braking torque. we use new spectropolarimetric measurements from the large binocular telescope to reconstruct the large - scale magnetic morphology, we reanalyze archival x - ray measurements to estimate the mass - loss rate, and we detect solar - like oscillations in photometry from the transiting exoplanet survey satellite, yielding precise stellar properties from asteroseismology. our estimate of the wind braking torque for 51 peg clearly places it in the wmb regime, driven by changes in the mass - loss rate and the magnetic field strength and morphology that substantially exceed theoretical expectations. although our revised stellar properties have minimal consequences for the characterization of the exoplanet, they have interesting implications for the current space weather environment of the system.
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arxiv:2401.01944
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often the result of a scientific experiment is given by the difference of measurements in two configurations, denoted by a and b. since the measurements are not obtained simultaneously, drift of the zero - point can bias the result. in practice measurement patterns are used to minimize this bias. the time sequence ab followed by ba, for example, would cancel a linear drift in the average difference a - b. we propose taking data with an alternating series abab.., and removing drift with a post - hoc analysis. we present an analysis method that removes bias from the result for drift up to polynomial order p. a statistical cost function c ( n ) is introduced to compare the uncertainty in the end result with that from using a raw data average. for a data set size n > 30 the statistical cost is negligible. for n < 30 the cost is plotted as a function of n and filter order p and the trade off between the size of the data set and p is discussed.
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arxiv:1009.1894
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we revisit the elegant observation of t. cover ' 65 which, perhaps, is not as well - known to the broader community as it should be. the first goal of the tutorial is to explain - - - through the prism of this elementary result - - - how to solve certain sequence prediction problems by modeling sets of solutions rather than the unknown data - generating mechanism. we extend cover ' s observation in several directions and focus on computational aspects of the proposed algorithms. the applicability of the methods is illustrated on several examples, including node classification in a network. the second aim of this tutorial is to demonstrate the following phenomenon : it is possible to predict as well as a combinatorial " benchmark " for which we have a certain multiplicative approximation algorithm, even if the exact computation of the benchmark given all the data is np - hard. the proposed prediction methods, therefore, circumvent some of the computational difficulties associated with finding the best model given the data. these difficulties arise rather quickly when one attempts to develop a probabilistic model for graph - based or other problems with a combinatorial structure.
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arxiv:1608.09014
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a derivation of the anomaly - induced transport phenomena - - - the chiral magnetic / vortical effect - - - is revisited based on the imaginary - time formalism of quantum field theory. considering the simplest anomalous system composed of a single weyl fermion, we provide two derivations : perturbative ( one - loop ) evaluation of the anomalous transport coefficient, and the anomaly matching for the local thermodynamic functional.
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arxiv:1902.09166
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we theoretically consider spin pumping in a junction between a ferromagnetic insulator ( fi ) and a two - dimensional electron gas ( 2deg ) in which the rashba and dresselhaus spin - orbit interactions coexist. using second - order perturbation theory, we derive an increase in linewidth in the case of an interfacial exchange coupling in a ferromagnetic resonance ( fmr ) experiment. we clarify how the enhancement of gilbert damping depends on the resonant frequency and spin orientation of the fi. we show that this setup of an fmr experiment can provide information on the spin texture of 2deg at the fermi surface.
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arxiv:2105.11193
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we find that the equations describing t - branes with constant worldvolume fields are identical to the equations found by banks, seiberg and shenker twenty years ago to describe longitudinal five - branes in the bfss matrix model. besides giving new ways to construct t - brane solutions, this connection also helps elucidate the physics of t - branes in the regime of parameters where their worldvolume fields are larger than the string scale. we construct explicit solutions to the banks - seiberg - shenker equations and show that the corresponding t - branes admit an alternative description as abelian branes at angles.
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arxiv:1703.06106
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we perform via $ \ gamma $ - convergence a 2d - 1d dimension reduction analysis of a single - slip elastoplastic body in large deformations. rigid plastic and elastoplastic regimes are considered. in particular, we show that limit deformations can essentially freely bend even if subjected to the most restrictive constraints corresponding to the elastically rigid single - slip regime. the primary challenge arises in the upper bound where the differential constraints render any bending without incurring an additional energy cost particularly difficult. we overcome this obstacle with suitable non - smooth constructions and prove that a lavrentiev phenomenon occurs if we artificially restrict our model to smooth deformations. this issue is absent if the differential constraints are appropriately softened.
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arxiv:2211.15345
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we demonstrate that the number of cycles for two problems of the family of generalized 3x + 1 mappings is possible finite.
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arxiv:1909.00213
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we study the anomalous hall effect ( ahe ) in tilted weyl metals with weak gaussian disorder under the kubo - streda formalism in this work. to separate the three different contributions, namely the intrinsic, side jump and skew scattering contribution, it is usually considered necessary to go to the eigenstate ( chiral ) basis of the kubo - streda formula. however, it is more straight - forward to compute the total hall current in the spin basis. for the reason, we develop a systematic and transparent scheme to separate the three different contributions in the spin basis for relativistic systems by building a one - to - one correspondence between the feynman diagrams of the different mechanisms in the chiral basis and the products of the symmetric and anti - symmetric part of the polarization operator in the spin basis. we obtain the three contributions of the ahe in tilted weyl metals by this scheme and found that the side jump contribution exceeds both the intrinsic and skew scattering contribution for the low - energy effective hamiltonian. we compared the anomalous hall current obtained from our scheme with the results from the semi - classical boltzmann equation approach under the relaxation time approximation and found that the results from the two approaches agree with each other in the leading order of the tilting velocity.
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arxiv:2204.09281
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