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the experimental and theoretical issues and challenges for extracting the neutron - neutron scattering length are discussed. particular emphasis is placed on recent results and their impact on the field. comments are made regarding current experimental and theoretical possibilities. | arxiv:0904.2787 |
the ability to measure polarisation, spectrum, temporal dynamics, and spatial amplitude and phase of optical beams is essential to study fundamental phenomena in laser dynamics, telecommunications and nonlinear optics. current characterisation techniques only apply in limited contexts. non - interferometric methods typically lack access to spatial phase, while phase - sensitive approaches necessitate either an auxiliary reference source or an adequate self - reference, neither of which is universally available. regardless of the reference, deciphering complex wavefronts of multiple co - propagating incoherent fields remains particularly challenging. here, we harness the principles of quantum state tomography to circumvent these limitations. a full description of an unknown beam is retrieved by measuring its temporally and spectrally resolved density matrices for both polarisations, using a spatial light modulator to display projective holograms and a single - mode fibre to guide the collected signal to a high - speed photodiode and a spectrometer. despite no spatial resolution of the detector and the intensity - only character of the collected signal, the method resolves multiple arbitrary spatial fields within a single beam, including their phase and amplitude, as well as their spatial coherence. leveraging the coherence information unlocks unambiguous determination of the spectral and temporal evolution of mutually incoherent fields, even when these spectrally overlap or have an identical time delay. we demonstrate these hallmark features by characterising the rich spatiotemporal and spectral output of a vertical - cavity surface - emitting laser diode that has so far resisted full analysis using existing techniques. | arxiv:2202.01932 |
despite the increasing maturity of model - driven software development ( mdd ), some research challenges remain open in the field of information systems ( is ). for instance, there is a need to improve modelling techniques so that they cover several development stages in an integrated way, and they facilitate the transition from analysis to design. this paper presents message structures, a technique for the specification of communicative interactions between the is and organisational actors. this technique can be used both in the analysis stage and in the design stage. during analysis, it allows abstracting from the technology that will support the is, and to complement business process diagramming techniques with the specification of the communicational needs of the organisation. during design, message structures serves two purposes : ( i ) it allows to systematically derive a specification of the is memory ( e. g. a uml class diagram ), ( ii ) and it allows to reason the user interface design using abstract patterns. this technique is part of communication analysis, a communication - oriented requirements engineering method, but it can be adopted in order to extend widely - used business process and functional requirements modelling techniques ( e. g. bpmn, use cases ). moreover, the paper presents two tools that support message structures, one uses the xtext technology, and the other uses the eclipse modelling framework. industrial experience has shown us that the technique can be adopted and applied in complex projects. | arxiv:1101.5341 |
a realistic and detailed description of neutrinos in binary neutron star ( bns ) mergers is essential to build reliable models of such systems. to this end, we present bns _ nurates, a novel open - source numerical library designed for the efficient on - the - fly computation of neutrino interactions, with particular focus on regimes relevant to bns mergers. bns _ nurates targets a higher level of accuracy and realism in the implementation of commonly employed reactions by accounting for relevant microphysics effects on the interactions, such as weak magnetism and mean field effects. it also includes the contributions of inelastic neutrino scattering off electrons and positrons and ( inverse ) nucleon decays. finally, it offers a way to reconstruct the neutrino distribution function in the framework of moment - based transport schemes. as a first application, we compute both energy - dependent and energy - integrated neutrino emissivities and opacities for conditions extracted from a bns merger simulation with m1 transport scheme. we find some qualitative differences in the results when considering the impact of the additional relevant reactions and of microphysics effects. for example, neutrino - electron / positron scattering reactions are important for the energy exchange of heavy - type neutrinos as they do not undergo semileptonic charged - current processes, when $ \ mu ^ \ pm $ are not accounted for. moreover, weak magnetism and mean field effects can significantly modify the contribution of $ \ beta $ processes for electron - type ( anti ) neutrinos, increasing at the same time the importance of ( inverse ) neutron decays. the improved treatment for the reaction rates also modifies the conditions at which neutrinos decouple from matter in the system, potentially affecting their emission spectra. | arxiv:2412.04570 |
one of the sources of solar energetic particle ( sep ) events is shocks that are driven by fast coronal mass ejections ( cmes ). they can accelerate seps up to relativistic energies and are attributed to the largest sep events. new studies suggest that cme - driven shocks can potentially accelerate electrons to mev energies in the vicinity of the sun. we focus on relativistic electrons associated with strong ip shocks between 2007 and 2019 to determine whether the shocks can keep accelerating such electrons up to 1 au distance. we have analyzed high energy telescope ( het ) observations aboard the stereo spacecraft of potential electron energetic storm particle ( esp ) events, characterized by intensity time series that peak at the time of, or close to, the associated cme - driven shock crossing. we present a new filtering method to assess the statistical significance of particle intensity increases and apply it to mev electron observations in the vicinity of interplanetary shocks. we identified 27 candidate events by visual inspection from a stereo in - situ shock list. our method identified nine clear cases, where a significant increase of mev electrons was found in association with a shock. typically, the highest statistical significance was observed in the highest het energy channel of electrons. all nine cases were associated with shocks driven by interplanetary cmes that showed large transit speeds, in excess of 900 km / s. in several cases multiple shocks were observed within one day of the shock related to the electron increase. although electron esp events at mev energies are found to be rare at 1 au our filtering method is not designed to identify a potential interplanetary shock contribution from distances closer to the sun. future observations taken during closer approaches to the sun will likely provide clarity on interplanetary shock acceleration of electrons. | arxiv:2301.05587 |
given a generic stable strongly parabolic $ sl ( 2, \ mathbb { c } ) $ - higgs bundle $ ( \ mathcal { e }, \ varphi ) $, we describe the family of harmonic metrics $ h _ t $ for the ray of higgs bundles $ ( \ mathcal { e }, t \ varphi ) $ for $ t \ gg0 $ by perturbing from an explicitly constructed family of approximate solutions $ h _ t ^ { \ mathrm { app } } $. we then describe the natural hyperk \ " ahler metric on $ \ mathcal { m } $ by comparing it to a simpler " semi - flat " hyperk \ " ahler metric. we prove that $ g _ { l ^ 2 } - g _ { \ mathrm { sf } } = o ( \ mathrm { e } ^ { - \ gamma t } ) $ along a generic ray, proving a version of gaiotto - moore - neitzke ' s conjecture. our results extend to weakly parabolic $ sl ( 2, \ mathbb { c } ) $ - higgs bundles as well. in the case of the four - puncture sphere, we describe the moduli space and metric more explicitly. in this case, we prove that the hyperk \ " ahler metric is alg and show that the rate of exponential decay is the conjectured optimal one, $ \ gamma = 4l $, where $ l $ is the length of the shortest geodesic on the base curve measured in the singular flat metric $ | \ mathrm { det } \, \ varphi | $. | arxiv:2001.03682 |
time series forecasting holds significant importance across various industries, including finance, transportation, energy, healthcare, and climate. despite the widespread use of linear networks due to their low computational cost and effectiveness in modeling temporal dependencies, most existing research has concentrated on regularly sampled and fully observed multivariate time series. however, in practice, we frequently encounter irregular multivariate time series characterized by variable sampling intervals and missing values. the inherent intra - series inconsistency and inter - series asynchrony in such data hinder effective modeling and forecasting with traditional linear networks relying on static weights. to tackle these challenges, this paper introduces a novel model named ait. ait utilizes an adaptive linear network capable of dynamically adjusting weights according to observation time points to address intra - series inconsistency, thereby enhancing the accuracy of temporal dependencies modeling. furthermore, by incorporating the transformer module on variable semantics embeddings, ait efficiently captures variable correlations, avoiding the challenge of inter - series asynchrony. comprehensive experiments across four benchmark datasets demonstrate the superiority of ait, improving prediction accuracy by 11 % and decreasing runtime by 52 % compared to existing state - of - the - art methods. | arxiv:2505.00590 |
the jump behavior of an infinitely active it \ ^ o semimartingale can be conveniently characterized by a jump activity index of blumenthal - getoor type, typically assumed to be constant in time. we study markovian semimartingales with a non - constant, state - dependent jump activity index and a non - vanishing continuous diffusion component. a nonparametric estimator for the functional jump activity index is proposed and shown to be asymptotically normal under combined high - frequency and long - time - span asymptotics. furthermore, we propose a nonparametric drift estimator which is robust to symmetric jumps of infinite variance and infinite variation, and which attains the same asymptotic variance as for a continuous diffusion process. simulations demonstrate the finite sample behavior of our proposed estimators. the mathematical results are based on a novel uniform bound on the markov generator of the jump diffusion. | arxiv:1811.06351 |
we present the exact solution of a system of fermi particles living on the sites of a bethe lattice with coordination number z and interacting through on - site u and nearest - neighbor v interactions. this is a physical realization of the extended hubbard model in the atomic limit. within the green ' s function and equations of motion formalism, we provide a comprehensive analysis of the model and we study the phase diagram at finite temperature in the whole model ' s parameter space, allowing for the on - site and nearest - neighbor interactions to be either repulsive or attractive. we find the existence of critical regions where charge ordering ( v > 0 ) and phase separation ( v < 0 ) are observed. this scenario is endorsed by the study of several thermodynamic quantities. | arxiv:0912.4137 |
we reformulate and extend our recently introduced quantum kinetic theory for interacting fermion and scalar fields. our formalism is based on the coherent quasiparticle approximation ( cqpa ) where nonlocal coherence information is encoded in new spectral solutions at off - shell momenta. we derive explicit forms for the cqpa propagators in the homogeneous background and show that the collision integrals involving the new coherence propagators need to be resummed to all orders in gradient expansion. we perform this resummation and derive generalized momentum space feynman rules including coherent propagators and modified vertex rules for a yukawa interaction. as a result we are able to set up self - consistent quantum boltzmann equations for both fermion and scalar fields. we present several examples of diagrammatic calculations and numerical applications including a simple toy model for coherent baryogenesis. | arxiv:1006.1929 |
we present an anisotropic analysis of baryon acoustic oscillation ( bao ) signal from the sdss - iv extended baryon oscillation spectroscopic survey ( eboss ) data release 14 ( dr14 ) quasar sample. the sample consists of 147, 000 quasars distributed over a redshift range of $ 0. 8 < z < 2. 2 $. we apply the redshift weights technique to the clustering of quasars in this sample and achieve a 4. 6 per cent measurement of the angular distance measurement $ d _ m $ at $ z = 2. 2 $ and hubble parameter $ h $ at $ z = 0. 8 $. we parameterize the distance - redshift relation, relative to a fiducial model, as a quadratic expansion. the coefficients of this expansion are used to reconstruct the distance - redshift relation and obtain distance and hubble parameter measurements at all redshifts within the redshift range of the sample. reporting the result at two characteristic redshifts, we determine $ d _ m ( z = 1 ) = 3405 \ pm305 \ ( r _ { \ rm d } / r _ { \ rm d, fid } ) \ { \ rm mpc } $, $ h ( z = 1 ) = 120. 7 \ pm 7. 3 \ ( r _ { \ rm d, fid } / r _ { \ rm d } ) \ { \ rm km } \ { \ rm s } ^ { - 1 } { \ rm mpc } ^ { - 1 } $ and $ d _ m ( z = 2 ) = 5325 \ pm249 \ ( r _ { \ rm d } / r _ { \ rm d, fid } ) \ { \ rm mpc } $, $ h ( z = 2 ) = 189. 9 \ pm 32. 9 \ ( r _ { \ rm d, fid } / r _ { \ rm d } ) \ { \ rm km } \ { \ rm s } ^ { - 1 } { \ rm mpc } ^ { - 1 } $. these measurements are highly correlated. we assess the outlook of bao analysis from the final quasar sample by testing the method on a set of mocks that mimic the noise level in the final sample. we demonstrate on these mocks that redshift weighting shrinks the measurement error by over 25 per cent | arxiv:1801.03038 |
in 1995, isaacs, kantor and spaltenstein proved that for a finite simple classical group g defined over a field with q elements, and for a prime divisor p of | g | distinct from the characteristic, the proportion of p - singular elements in g ( elements with order divisible by p ) is at least a constant multiple of ( 1 - 1 / p ) / e, where e is the order of q modulo p. motivated by algorithmic applications, we define a subfamily of p - singular elements, called p - abundant elements, which leave invariant certain " large " subspaces of the natural g - module. we find explicit upper and lower bounds for the proportion of p - abundant elements in g, and prove that it approaches a ( positive ) limiting value as the dimension of g tends to infinity. it turns out that the limiting proportion of p - abundant elements is at least a constant multiple of the isaacs - kantor - spaltenstein lower bound for the proportion of all p - singular elements. | arxiv:1205.1454 |
in this paper we test the use of a deep learning approach to automatically count wandering albatrosses in very high resolution ( vhr ) satellite imagery. we use a dataset of manually labelled imagery provided by the british antarctic survey to train and develop our methods. we employ a u - net architecture, designed for image segmentation, to simultaneously classify and localise potential albatrosses. we aid training with the use of the focal loss criterion, to deal with extreme class imbalance in the dataset. initial results achieve peak precision and recall values of approximately 80 %. finally we assess the model ' s performance in relation to inter - observer variation, by comparing errors against an image labelled by multiple observers. we conclude model accuracy falls within the range of human counters. we hope that the methods will streamline the analysis of vhr satellite images, enabling more frequent monitoring of a species which is of high conservation concern. | arxiv:1907.02040 |
this paper, in french, describes a series of completely different behaviours of the mechanics of granular matter, which are obtained experimentally using periodic forcing at different amplitude, frequency and orientation. it starts with the problem of granular dissipative gas which has been investigated in micro - gravity ; it is found that such a gas exists only at very low density ; it is shown also that clustering occurs at larger density. is this a phase transition? the problem of dissipative sinai billiard is then investigated briefly ; is it ergodic? an experiment on propagation of acoustic wave is studied, with peculiar attention paid to scattering and diffusion that occurs when acoustic wavelength is comparable to the grain size. a third experiment demonstrates that bulk convection can be induced by slow ( quasi static ) horizontal forcing ; this flow is related to the quasi static rheology of granular matter, but looks rather like convection occurring under " dynamic vibration ". a fourth experiment describes pure inertial effect, making the sand behaving as a perfect ( non viscous ) fluid ; in particular, it is shown that a static swell 9that does not propagate ) is enforced at the interface between liquid and sand by strong periodic horizontal forcing. pacs # : 5. 40 ; 45. 70 ; 62. 20 ; 83. 70. fn | arxiv:cond-mat/0507261 |
we use the blm scale - fixing prescription to derive a renormalization - scheme invariant relation between the coefficient function for the bjorken sum rule for polarized deep inelastic scattering and the $ r $ - ratio for the $ e ^ + e ^ - $ annihilation cross section. this relation provides a generalization of the crewther relation to non - conformally invariant gauge theories. the derived relations allow one to calculate unambiguously without renormalization scale or scheme ambiguity the effective charges of the polarized bjorken and the gross - llewellen smith sum rules from the experimental value for the effective charge associated with $ r $ - ratio. present data are consistent with the generalized crewther relations, but measurements at higher precision and energies will be needed to decisively test these fundamental relations in qcd. | arxiv:hep-ph/9512367 |
the kato - bloch perturbation formalism is used to present a density - matrix renormalization - group ( dmrg ) method for strongly anisotropic two - dimensional systems. this method is used to study heisenberg chains weakly coupled by the transverse couplings $ j _ { \ perp } $ and $ j _ { d } $ ( along the diagonals ). an extensive comparison of the renormalization group and quantum monte carlo results for parameters where the simulations by the latter method are possible shows a very good agreement between the two methods. it is found, by analyzing ground state energies and spin - spin correlation functions, that there is a transition between two ordered magnetic states. when $ j _ { d } / j _ { \ perp } \ alt 0. 5 $, the ground state displays a n \ ' eel order. when $ j _ { d } / j _ { \ perp } \ agt 0. 5 $, a collinear magnetic ground state in which interchain spin correlations are ferromagnetic becomes stable. in the vicinity of the transition point, $ j _ { d } / j _ { \ perp } \ approx 0. 5 $, the ground state is disordered. but, the nature of this disordered ground state is unclear. while the numerical data seem to show that the chains are disconnected, the possibility of a genuine disordered two - dimensional state, hidden by finite size effects, cannot be excluded. | arxiv:cond-mat/0305608 |
the addition of durative actions to pddl2. 1 sparked some controversy. fox and long argued that actions should be considered as instantaneous, but can start and stop processes. ultimately, a limited notion of durative actions was incorporated into the language. i argue that this notion is still impoverished, and that the underlying philosophical position of regarding durative actions as being a shorthand for a start action, process, and stop action ignores the realities of modelling and execution for complex systems. | arxiv:1109.5666 |
named entity recognition ( ner ) plays an important role in text - based information retrieval. in this paper, we combine bidirectional long short - term memory ( bi - lstm ) \ cite { hochreiter1997, schuster1997 } with conditional random field ( crf ) \ cite { lafferty2001 } to create a novel deep learning model for the ner problem. each word as input of the deep learning model is represented by a word2vec - trained vector. a word embedding set trained from about one million articles in 2018 collected through a vietnamese news portal ( baomoi. com ). in addition, we concatenate a word2vec \ cite { mikolov2013 } - trained vector with semantic feature vector ( part - of - speech ( pos ) tagging, chunk - tag ) and hidden syntactic feature vector ( extracted by bi - lstm nerwork ) to achieve the ( so far best ) result in vietnamese ner system. the result was conducted on the data set vlsp2016 ( vietnamese language and speech processing 2016 \ cite { vlsp2016 } ) competition. | arxiv:1912.01109 |
we present the results from the first measurements of the time - correlated pulse - height ( tcph ) distributions from 4. 5 kg sphere of $ \ alpha $ - phase weapons - grade plutonium metal in five configurations : bare, reflected by 1. 27 cm and 2. 54 cm of tungsten, and 2. 54 cm and 7. 62 cm of polyethylene. a new method for characterizing source multiplication and shielding configuration is also demonstrated. the method relies on solving for the underlying fission chain timing distribution that drives the spreading of the measured tcph distribution. we found that a gamma distribution fits the fission chain timing distribution well and that the fit parameters correlate with both multiplication ( rate parameter ) and shielding material types ( shape parameter ). the source - to - detector distance was another free parameter that we were able to optimize, and proved to be the most well constrained parameter. mcnpx - polimi simulations were used to complement the measurements and help illustrate trends in these parameters and their relation to multiplication and the amount and type of material coupled to the subcritical assembly. | arxiv:1701.03848 |
context : type ii supernovae provide a direct way to estimate distances through the expanding photosphere method, which is independent of the cosmic distance ladder. a recently introduced gaussian process - based method allows for a fast and precise modelling of spectral time series, which puts accurate and computationally cheap type ii - based absolute distance determinations within reach. aims : the goal of the paper is to assess the internal consistency of this new modelling technique coupled with the distance estimation empirically, using the spectral time series of supernova siblings, i. e. supernovae that exploded in the same host galaxy. methods : we use a recently developed spectral emulator code, which is trained on \ textsc { tardis } radiative transfer models and is capable of a fast maximum likelihood parameter estimation and spectral fitting. after calculating the relevant physical parameters of supernovae we apply the expanding photosphere method to estimate their distances. finally, we test the consistency of the obtained values by applying the formalism of bayes factors. results : the distances to four different host galaxies were estimated based on two supernovae in each. the distance estimates are not only consistent within the errors for each of the supernova sibling pairs, but in the case of two hosts they are precise to better than 5 \ %. conclusions : even though the literature data we used was not tailored for the requirements of our analysis, the agreement of the final estimates shows that the method is robust and is capable of inferring both precise and consistent distances. by using high - quality spectral time series, this method can provide precise distance estimates independent of the distance ladder, which are of high value for cosmology. | arxiv:2302.03112 |
small angle neutron scattering ( sans ) is a non - destructive technique utilized to probe the nano - to mesoscale structure of materials by analyzing the scattering pattern of neutrons. accelerating sans acquisition for in - situ analysis is essential, but it often reduces the signal - to - noise ratio ( snr ), highlighting the need for methods to enhance snr even with short acquisition times. while deep learning ( dl ) can be used for enhancing snr of low quality sans, the amount of experimental data available for training is usually severely limited. we address this issue by proposing a plug - and - play restoration for sans ( pr - sans ) that uses domain - adapted priors. the prior in pr - sans is initially trained on a set of generic images and subsequently fine - tuned using a limited amount of experimental sans data. we present a theoretical convergence analysis of pr - sans by focusing on the error resulting from using inexact domain - adapted priors instead of the ideal ones. we demonstrate with experimentally collected sans data that pr - sans can recover high - snr 2d sans detector images from low - snr detector images, effectively increasing the snr. this advancement enables a reduction in acquisition times by a factor of 12 while maintaining the original signal quality. | arxiv:2403.10495 |
astrochemical surface reactions are thought to be responsible for the formation of complex organic molecules, which are of potential importance for the origin of life. in a situation, when the chemical composition of dust surfaces is not precisely known, the fundamental knowledge concerning such reactions gains significance. we describe an experimental technique, which can be used to measure the energy released in reactions of a single pair of reactants. these data can be directly compared with the results of quantum chemical computations leading to unequivocal conclusions regarding the reaction pathways and the presence of energy barriers. it allows for predicting the outcomes of astrochemical surface reactions with higher accuracy compared to that achieved based on gas - phase studies. however, for the highest accuracy, some understanding of the catalytic influence of specific surfaces on the reactions is required. the new method was applied to study the reactions of c atoms with h2, o2, and c2h2. the formation of hch, co + o, and triplet cyclic - c3h2 products has been revealed, correspondingly. | arxiv:2211.04437 |
we have used effective reaction rates ( err ) for the helium burning reactions to predict the yield of the gamma - emitting nuclei 26al, 44ti, and 60fe in core col - lapse supernovae. the variations in the predicted yields for values of the reaction rates allowed by the err are much smaller than obtained previously, and smaller than other uncertainties. a " filter " for supernova nucleosynthesis yields based on pre - supernova structure was used to estimate the effect of failed supernovae on the initial mass function - averaged yields ; this substantially reduced the yields of all these isotopes, but the predicted yield ratio 60fe / 26al was little affected. the robustness of this ratio is promising for comparison with data, but it is larger than observed in nature ; possible causes for this discrepancy are discussed. | arxiv:1704.01240 |
we propose and discuss a theoretical scheme to speed up zeno dynamic passage by an external acceleration hamiltonian. this scheme is a flexible and experimentally feasible acceleration because the acceleration hamiltonian does not adhere rigidly to an invariant relationship, whereas it can be a more general form $ \ sum u _ { j } ( t ) h _ { cj } $. here $ h _ { cj } $ can be arbitrarily selected without any limitation, and therefore one can always construct an acceleration hamiltonian by only using realizable $ h _ { cj } $. applying our scheme, we finally design an experimentally feasible hamiltonian as an example to speed up an entanglement preparation passage. | arxiv:1608.07884 |
let g be a connected reductive group. to any irreducible g - variety one associates a certain linear group generated by reflections called the weyl group. weyl groups play an important role in the study of embeddings of homogeneous spaces. we establish algorithms for computing weyl groups for homogeneous spaces and affine homogeneous vector bundles. for some special classes of g - varieties ( affine homogeneous vector bundles of maximal rank, affine homogeneous spaces, homogeneous spaces of maximal rank with discrete group of central automorphisms ) we compute weyl groups more or less explicitly. | arxiv:math/0612559 |
the falicov - kimball model was introduced in 1969 as a statistical model for metal - insulator transitions ; it includes itinerant and localized electrons that mutually interact with a local coulomb interaction and is the simplest model of electron correlations. it can be solved exactly with dynamical mean - field theory in the limit of large spatial dimensions which provides an interesting benchmark for the physics of locally correlated systems. in this review, we develop the formalism for solving the falicov - kimball model from a path - integral perspective, and provide a number of expressions for single and two - particle properties. we examine many important theoretical results that show the absence of fermi - liquid features and provide a detailed description of the static and dynamic correlation functions and of transport properties. the parameter space is rich and one finds a variety of many - body features like metal - insulator transitions, classical valence fluctuating transitions, metamagnetic transitions, charge density wave order - disorder transitions, and phase separation. at the same time, a number of experimental systems have been discovered that show anomalies related to falicov - kimball physics [ including ybincu4, euni2 ( si [ 1 - x ] gex ) 2, nii2 and taxn ]. | arxiv:cond-mat/0301188 |
in matching theory, barrier sets ( also known as tutte sets ) have been studied extensively due to its connection to maximum matchings in a graph. in this paper, we first define $ \ theta $ - barrier sets. our definition of a $ \ theta $ - barrier set is slightly different from that of a barrier set. however we show that $ \ theta $ - barrier sets and barrier sets have similar properties. in particular, we prove a generalized berge ' s formula and give a characterization for the set of all $ \ theta $ - special vertices in a graph. | arxiv:0909.5249 |
it is well - known that gravitational waves can induce electromagnetic perturbations in magnetised plasmas, with production occurring via the direct coupling of gravitational waves to the background magnetic field : this is the so - called gertsenshtein effect. in this short work, we consider the direct gravitational perturbations of charge carriers via their minimal coupling to gravity in a collisionless plasma. we find that for isotropic plasmas, no secondary plasma perturbations are generated. however, when an anisotropy is introduced in the form of a background plasma current, we find that gravitational waves can induce a secondary current. for a constant dc background current, the secondary current inherits the ac frequency of the gravitational waves. it will certainly be interesting to investigate this effect in astrophysical plasmas in future work as well as its wider phenomenological consequences. | arxiv:2408.02553 |
we use dual equivalence to give a short, combinatorial proof that stanley symmetric functions are schur positive. we introduce weak dual equivalence, and use it to give a short, combinatorial proof that schubert polynomials are key positive. to demonstrate further the utility of this new tool, we use weak dual equivalence to prove a nonnegative littlewood - - richardson rule for the key expansion of the product of a key polynomial and a schur polynomial, and to introduce skew key polynomials that, when skewed by a partition, expand nonnegatively in the key basis. | arxiv:1702.04051 |
it is proven that, in any given base, there are infinitely many palindromic numbers having at most six prime divisors, each relatively large. the work involves equidistribution estimates for the palindromes in residue classes to large moduli, offering upper bounds for moments and averages of certain products closely related to exponential sums over palindromes | arxiv:2307.16637 |
i review the uncertainties in two observational constraints of the galactic disc chemical evolution : the metallicity distribution ( md ) of long - lived dwarfs and the age - metallicity relation ( amr ). it is shown first that the observed md, designed with standard methods, is more fit to a closed - box model than to the infall md. we argue that this is due to the specific contribution of the thick disc population, which has been overlooked both in the derivation of the observed md and in the standard chemical evolution models. although this agreement disqualifies the md as the best supportive evidence for infall, we argue that the evolution must be more complex than described by either the closed - box or the standard infall models. a new age - metallicity distribution is obtained, where particularities of the previous recent determinations are phased out. the new amr shows a mean increase limited to about a factor of 2 in z over the disc age. it is shown that below 3 gyrs, the dispersion in metallicity is about 0. 1 dex, which, ( given the observational uncertainties ), is compatible with the small cosmic dispersion measured on the interstellar medium and meteoritic pre - solar dust grains. a population that is progressively older and more metal rich arises at a metallicity greater than that of the hyades, to reach [ fe / h ] ~ + 0. 5 dex at ages > 5 gyr. we suggest that this is best explained by radial migration. a symmetrical widening towards lower metallicities is seen at about the same age. finally, the new derived ages are sufficiently consistent that an amr within the thick disc is confirmed. these new features altogether draw a picture of the chemical evolution where dynamical effects and complexity in the amr dominate, rather than a generalized high dispersion at all ages. ( abridged ) | arxiv:astro-ph/0609523 |
despite the extensive amount of scholarly work done on indian mathematics in the last 200 years, the conditions under which it originated and evolved is still not clear. often, one reads the ancient texts with the present concepts and methods in mind. the fact of absence of script over a long stretch of indian history in ancient times also gets overlooked in such readings. the purpose of this article is to explore the journey of mathematics by examining what the ancient texts tell us about the nature of mathematics in their times. what one finds from the investigation of arithmetic, geometry and algebra is that while it was concrete and context bound, rooted in solving practical problems in ancient times, indian mathematics transitioned to context free, abstract stage with the advent of algebra supported by writing. | arxiv:2406.10147 |
oblivious ram simulation is a method for achieving confidentiality and privacy in cloud computing environments. it involves obscuring the access patterns to a remote storage so that the manager of that storage cannot infer information about its contents. existing solutions typically involve small amortized overheads for achieving this goal, but nevertheless involve potentially huge variations in access times, depending on when they occur. in this paper, we show how to de - amortize oblivious ram simulations, so that each access takes a worst - case bounded amount of time. | arxiv:1107.5093 |
a unitary operator $ v $ and a rank $ 2 $ operator $ r $ acting on a hilbert space $ \ h $ are constructed such that $ v + r $ is hypercyclic. this answers affirmatively a question of salas whether a finite rank perturbation of a hyponormal operator can be supercyclic. | arxiv:1008.3490 |
this paper explores a discrete energy state transition model for energy harvesting ( eh ) in cell - free massive multiple - input multiple - output ( cf - mmimo ) networks. multiple - antenna access points ( aps ) provide wireless power and information to single - antenna ue equipment ( ues ). the harvested energy at the ues is used for both uplink ( ul ) training and data transmission. we investigate the energy transition probabilities based on the energy differential achieved in each coherence interval. a markov chain - based stochastic process is introduced to characterize the evolving ue energy status. a detailed statistical model is developed for a non - linear eh circuit at the ues, using the derived closed - form expressions for the mean and variance of the harvested energy. more specifically, simulation results confirm that the proposed gamma distribution approximation can accurately capture the statistical behavior of the harvested energy. furthermore, the energy state transitions are evaluated using the proposed markov chain - based framework, while mathematical expressions for the self, positive and negative transition probabilities of the discrete energy states are also presented. our numerical results depict that increasing the number of aps with a constant number of service antennas provides significant improvement in the positive energy state transition and reduces the negative transition probabilities of the overall network. | arxiv:2409.01127 |
the site was bounded on the south by north avenue, and on the west by cherry street. he then sold five adjoining acres of land to the state for us $ 10, 000, ( equivalent to $ 350, 000 in 2024 ). this land was near atlanta ' s northern city limits at the time of its founding, although the city has since expanded several miles beyond it. a historical marker on the large hill in central campus says that the site occupied by the school ' s first buildings once held fortifications to protect atlanta during the atlanta campaign of the american civil war. the surrender of the city took place in 1864 on what is today the southwestern boundary of the georgia tech campus. = = = early years = = = the georgia school of technology opened in the fall of 1888 with two buildings. one building ( now tech tower, an administrative headquarters ) had classrooms to teach students ; the second building featured a shop and had a foundry, forge, boiler room, and engine room. it was designed for students to work and produce goods to sell and fund the school. the two buildings were equal in size to show the importance of teaching both the mind and the hands, though, at the time, there was some disagreement to whether the machine shop should have been used to turn a profit. on october 20, 1905, u. s. president theodore roosevelt visited georgia tech. on the steps of tech tower, roosevelt delivered a speech about the importance of technological education. he then shook hands with every student. georgia tech ' s evening school of commerce began holding classes in 1912. the evening school admitted its first female student in 1917, although the state legislature did not officially authorize attendance by women until 1920. annie t. wise became the first female graduate in 1919 and was georgia tech ' s first female faculty member the following year. in 1931, the board of regents transferred control of the evening school of commerce to the university of georgia ( uga ) and moved the civil and electrical engineering courses at uga to tech. tech replaced the commerce school with what later became the college of business. the commerce school would later split from uga and eventually become georgia state university. in 1934, the engineering experiment station ( later known as the georgia tech research institute ) was founded by w. harry vaughan with an initial budget of $ 5, 000 ( equivalent to $ 117, 525 in 2024 ) and 13 part - time faculty. in the mid to late 40s, president blake van leer had a focus on making georgia tech the " mit of the south. | https://en.wikipedia.org/wiki/Georgia_Tech |
a well - - known fact in spectral graph theory is the existence of pairs of isospectral nonisomorphic graphs ( known as pings ). the work of a. j. schwenk ( in 1973 ) and of c. godsil and b. mckay ( in 1982 ) shed some light on the explanation of the presence of isospectral graphs, and they gave routines to construct pings. here, we consider the godsil - mckay - - type routines developed for graphs, whose adjacency matrices are $ ( 0, 1 ) $ - matrices, to the level of signed graphs, whose adjacency matrices allow the presence of $ - 1 $ ' s. we show that, with suitable adaption, such routines can be successfully ported to signed graphs, and we can build pairs of cospectral switching nonisomorphic signed graphs. | arxiv:1908.02220 |
we investigate $ e ^ { + } e ^ { - } \ to \ gamma \ gamma $ process within the seiberg - witten expanded noncommutative standard model ( ncsm ) scenario in the presence of anomalous triple gauge boson couplings. this study is done with and without initial beam polarization and we restrict ourselves to leading order effects of non commutativity i. e. $ o ( \ theta ) $. the non commutative ( nc ) corrections are sensitive to the electric component ( $ \ vec { \ theta } _ e $ ) of nc parameter. we include the effects of earth rotation in our analysis. this study is done by investigating the effects of non commutativity on different time averaged cross section observables. we have also defined forward backward asymmetries which will be exclusively sensitive to anomalous couplings. we have looked into the sensitivity of these couplings at future experiments at the international linear collider ( ilc ). this analysis is done under realistic ilc conditions with the center of mass energy ( c. m. ) $ \ sqrt { s } = 800 $ gev and integrated luminosity l = 500fb $ { } ^ { - 1 } $. the scale of non commutativity is assumed to be $ \ lambda = 1 $ tev. the limits on anomalous couplings of the order $ 10 ^ { - 1 } $ from forward backward asymmetries while much stringent limits of the order $ 10 ^ { - 2 } $ from total cross section are obtained if no signal beyond sm is seen. | arxiv:1111.5173 |
we simultaneously study gravitational waves ( gws ) and free axions emitted from axionic string - wall networks in the early universe using advanced 3d lattice simulations. our simulations start before the peccei - quinn phase transition and end with the destruction of string - wall networks below the qcd scale. the axion dark matter ( dm ) relic abundance radiated from string - wall networks are updated and refined for the scenarios of $ n _ { \ rm dw } > 1 $. in this scenario, we observe that the gw spectrum is almost independent of the bias term and $ n _ { \ rm dw } $, and $ \ omega _ { \ rm gw } h ^ 2 \ propto f ^ { 1. 29 } ( f ^ { - 0. 43 } ) $ in the ir and middle - frequency regions. after considering the constraints from dm relic abundance, we found that the qcd axion model predicts undetectable gw emissions, and the axion - like particles model allows for a detectable gw signal in the nano - hertz to the milli - hertz frequency range corresponding to axion masses range from kev to tev. for $ n _ { \ rm dw } = 1 $, the gw energy density appears undetectable for qcd axions and axion - like particles. | arxiv:2311.02011 |
we prove that all spaces of finite assouad - nagata dimension admit a good order for travelling salesman problem, and provide sufficient conditions under which the converse is true. we formulate a conjectural characterisation of spaces of finite $ an $ - dimension, which would yield a gap statement for the efficiency of orders on metric spaces. under assumption of doubling, we prove a stronger gap phenomenon about all orders on a given metric space. | arxiv:2109.12181 |
we show that the ulam method applied to dynamical symplectic maps generates ulam networks which belong to the class of small world networks appearing for social networks of people, actors, power grids, biological networks and facebook. we analyze the small world properties of ulam networks on examples of the chirikov standard map and the arnold cat map showing that the number of degrees of separation, or the erd \ " os number, grows logarithmically with the network size for the regime of strong chaos. this growth is related to the lyapunov instability of chaotic dynamics. the presence of stability islands leads to an algebraic growth of the erd \ " os number with the network size. we also compare the time scales related with the erd \ " os number and the relaxation times of the perron - frobenius operator showing that they have a different behavior. | arxiv:1807.05204 |
in this paper we investigate problematic practices and consequences of large scale vision datasets. we examine broad issues such as the question of consent and justice as well as specific concerns such as the inclusion of verifiably pornographic images in datasets. taking the imagenet - ilsvrc - 2012 dataset as an example, we perform a cross - sectional model - based quantitative census covering factors such as age, gender, nsfw content scoring, class - wise accuracy, human - cardinality - analysis, and the semanticity of the image class information in order to statistically investigate the extent and subtleties of ethical transgressions. we then use the census to help hand - curate a look - up - table of images in the imagenet - ilsvrc - 2012 dataset that fall into the categories of verifiably pornographic : shot in a non - consensual setting ( up - skirt ), beach voyeuristic, and exposed private parts. we survey the landscape of harm and threats both society broadly and individuals face due to uncritical and ill - considered dataset curation practices. we then propose possible courses of correction and critique the pros and cons of these. we have duly open - sourced all of the code and the census meta - datasets generated in this endeavor for the computer vision community to build on. by unveiling the severity of the threats, our hope is to motivate the constitution of mandatory institutional review boards ( irb ) for large scale dataset curation processes. | arxiv:2006.16923 |
for physical human - robot interactions ( phri ), a robot needs to estimate the accurate body pose of a target person. however, in these phri scenarios, the robot cannot fully observe the target person ' s body with equipped cameras because the target person must be close to the robot for physical interaction. this close distance leads to severe truncation and occlusions and thus results in poor accuracy of human pose estimation. for better accuracy in this challenging environment, we propose an active measurement and sensor fusion framework of the equipped cameras with touch and ranging sensors such as 2d lidar. touch and ranging sensor measurements are sparse but reliable and informative cues for localizing human body parts. in our active measurement process, camera viewpoints and sensor placements are dynamically optimized to measure body parts with higher estimation uncertainty, which is closely related to truncation or occlusion. in our sensor fusion process, assuming that the measurements of touch and ranging sensors are more reliable than the camera - based estimations, we fuse the sensor measurements to the camera - based estimated pose by aligning the estimated pose towards the measured points. our proposed method outperformed previous methods on the standard occlusion benchmark with simulated active measurement. furthermore, our method reliably estimated human poses using a real robot, even with practical constraints such as occlusion by blankets. | arxiv:2310.08116 |
the rapid rotation ( p = 0. 44 d ) of the m dwarf v374peg ( m4 ) along with its intense magnetic field point toward magneto - centrifugal acceleration of a coronal wind. in this work, we investigate the structure of the wind of v374peg by means of 3d magnetohydrodynamical ( mhd ) numerical simulations. for the first time, an observationally derived surface magnetic field map is implemented in mhd models of stellar winds for a low mass star. we show that the wind of v374peg deviates greatly from a low - velocity, low - mass - loss rate solar - type wind. we find general scaling relations for the terminal velocities, mass - loss rates, and spin - down times of highly magnetized m dwarfs. in particular, for v374peg, our models show that terminal velocities across a range of stellar latitudes reach ~ ( 1500 - 2300 ) n _ { 12 } ^ { - 1 / 2 } km / s, where n _ { 12 } is the coronal wind base density in units of 10 ^ { 12 } cm ^ { - 3 }, while the mass - loss rates are about 4 x 10 ^ { - 10 } n _ { 12 } ^ { 1 / 2 } msun / yr. we also evaluate the angular - momentum loss of v374peg, which presents a rotational braking timescale ~ 28 n _ { 12 } ^ { - 1 / 2 } myr. compared to observationally derived values from period distributions of stars in open clusters, this suggests that v374peg may have low coronal base densities ( < 10 ^ { 11 } cm ^ { - 3 } ). we show that the wind ram pressure of v374peg is about 5 orders of magnitude larger than for the solar wind. nevertheless, a small planetary magnetic field intensity ( ~ 0. 1g ) is able to shield a planet orbiting at 1 au against the erosive effects of the stellar wind. however, planets orbiting inside the habitable zone of v374peg, where the wind ram pressure is higher, might be facing a more significant atmospheric erosion. in that case, higher planetary magnetic fields of, at least, about half the magnetic field intensity of jupiter, are required to protect the planet ' s atmosphere. | arxiv:1010.4762 |
we report a theoretical analysis of the phonon thermal conductance, \ kappa ( t ), for single wall carbon nanotubes ( swcn ). in a range of low temperatues up to 100k, \ kappa ( t ) of perfect swcn is found to increase with temperature, approximately, in a parabolic fashion. this is qualitatively consistent with recent experimental measurements where the tube - tube interactions are negligibly weak. when the carbon - carbon bond length is slightly varied, \ kappa ( t ) is found to be qualitatively unaltered which implies that the anharmonic effect does not change the qualitative behavior of \ kappa ( t ). | arxiv:cond-mat/0210395 |
we show that, for many lie superalgebras admitting a compatible $ \ mathbb { z } $ - grading, kac induction functor gives rise to a bijection between simple supermodules over a lie superalgebra and simple supermodules over the even part of this lie superalgebra. this reduces the classification problem for the former to the one for the latter. our result applies to all classical lie superalgebra of type $ i $, in particular, to the general linear lie superalgebra $ \ gl ( m | n ) $. in the latter case we also show that the rough structure of simple $ \ gl ( m | n ) $ - supermodules and also that of kac supermodules depends only on the annihilator of the $ \ mf { gl } ( m ) \ oplus \ mf { gl } ( n ) $ - input and hence can be computed using the combinatorics of bgg category $ \ mathcal { o } $. | arxiv:1801.00654 |
in arxiv : 1008. 3825, totaro gave examples of a k3 surface such that its automorphism group is not commensurable with an arithmetic group, answering a question of mazur. we give examples of rational surfaces with the same property. our examples $ y $ are looijenga pairs, i. e., there is a connected singular nodal curve $ d \ subset y $ such that $ k _ { y } + d = 0 $. | arxiv:2310.08768 |
we present an optical wavefront shaping approach that allows tracking and localization of signal hidden inside or behind a scattering medium. the method combines traditional feedback based wavefront shaping together with a switch function, controlled by two different signals. a simple, in transmission imaging system is used with two detectors : one monitors the speckle signature and the other tracks the fully hidden signal ( e. g., fluorescent beads ). the algorithm initially finds the optimal incident wavefront to maximize light transmission to generate a focus in the scattering medium. this modulation process redirects the scattered input signal inducing instantaneous changes in both monitored signals, which in turn locates the hidden objects. once the response from the hidden target becomes distinct, the algorithm switches to use this signal as the feedback. we provide experimental demonstrations as a proof of concept of our approach. potential applications of our method include extracting information from biological samples and developing non - invasive diagnosis methods. | arxiv:2201.11225 |
mobile health systems in recent times, have notably improved the healthcare sector by empowering patients to actively participate in their health, and by facilitating access to healthcare professionals. effective operation of these mobile systems nonetheless, requires high level of intelligence and expertise implemented in the form of decision support systems ( dss ). however, common challenges in the implementation include generalization and reliability, due to the dynamics and incompleteness of information presented to the inference models. in this paper, we advance the use of ad hoc mobile decision support system to monitor and detect triggers and early symptoms of respiratory distress provoked by strenuous physical exertion. the focus is on the application of certainty theory to model inexact reasoning by the mobile monitoring system. the aim is to develop a mobile tool to assist patients in managing their conditions, and to provide objective clinical data to aid physicians in the screening, diagnosis, and treatment of the respiratory ailments. we present the proposed model architecture and then describe an application scenario in a clinical setting. we also show implementation of an aspect of the system that enables patients in the self - management of their conditions. | arxiv:2110.07898 |
we demonstrate an end - to - end framework to improve the resilience of man - made systems to unforeseen events. the framework is based on a physics - based digital twin model and three modules tasked with real - time fault diagnosis, prognostics and reconfiguration. the fault diagnosis module uses model - based diagnosis algorithms to detect and isolate faults and generates interventions in the system to disambiguate uncertain diagnosis solutions. we scale up the fault diagnosis algorithm to the required real - time performance through the use of parallelization and surrogate models of the physics - based digital twin. the prognostics module tracks the fault progressions and trains the online degradation models to compute remaining useful life of system components. in addition, we use the degradation models to assess the impact of the fault progression on the operational requirements. the reconfiguration module uses pddl - based planning endowed with semantic attachments to adjust the system controls so that the fault impact on the system operation is minimized. we define a resilience metric and use the example of a fuel system model to demonstrate how the metric improves with our framework. | arxiv:2208.14525 |
gesture recognition opens up new ways for humans to intuitively interact with machines. especially for service robots, gestures can be a valuable addition to the means of communication to, for example, draw the robot ' s attention to someone or something. extracting a gesture from video data and classifying it is a challenging task and a variety of approaches have been proposed throughout the years. this paper presents a method for gesture recognition in rgb videos using openpose to extract the pose of a person and dynamic time warping ( dtw ) in conjunction with one - nearest - neighbor ( 1nn ) for time - series classification. the main features of this approach are the independence of any specific hardware and high flexibility, because new gestures can be added to the classifier by adding only a few examples of it. we utilize the robustness of the deep learning - based openpose framework while avoiding the data - intensive task of training a neural network ourselves. we demonstrate the classification performance of our method using a public dataset. | arxiv:1906.12171 |
this study uses plasma - profile data from the eurofusion pedestal database, focusing on the electron - temperature and electron - density profiles in the edge region of h - mode elmy jet iter - like - wall ( ilw ) pulses. we make systematic predictions of the electron - temperature pedestal, using the density profiles and engineering parameters of the pulses as inputs. we first present a machine - learning algorithm that, given more inputs than theory - based modelling and 80 \ % of the database as training data, can reconstruct the remaining 20 \ % of temperature profiles within 20 \ % of the experimental values, including accurate estimates of the pedestal width and location. the most important engineering parameters for these predictions are magnetic field strength, particle fuelling rate, plasma current, and strike - point configuration. this confirms the potential of accurate pedestal prediction using large databases. next, we take a simple theoretical approach assuming a local power - law relationship between the gradients of density ( $ r / l _ { n _ e } $ ) and temperature ( $ r / l _ { t _ e } $ ) : $ r / l _ { t _ e } = a \ left ( r / l _ { n _ e } \ right ) ^ \ alpha $ with $ \ alpha \ approx 0. 4 $ fits well in the steep - gradient region. when $ a $ and $ \ alpha $ are fit independently for each pedestal, a one - to - one correlation emerges, also valid for jet - c data. for $ \ alpha = 1 $, $ a \ equiv \ eta _ e $, a known control parameter for turbulence in slab - etg theory. measured values of $ \ eta _ e $ in the steep - gradient region lie well above the slab - etg stability threshold, suggesting a nonlinear threshold shift or a supercritical turbulent state. finally, we test heat - flux scalings motivated by gyrokinetic simulations, and we provide best - fit parameters for reconstructing jet - ilw pedestals. these models require additional experimental inputs to reach the accuracy of the machine - learning reconstructions. | arxiv:2504.17486 |
in this paper, we study a close relationship between relative cluster tilting theory in extriangulated categories and tau - tilting theory in module categories. our main results show that relative rigid objects are in bijection with $ \ tau $ - rigid pairs, and also relative maximal rigid objects with support tau - tilting pairs under some assumptions. these results generalize their work by adachi - iyama - reiten, yang - zhu and fu - geng - liu. finally, we introduce mutation of relative maximal rigid objects and show that any basic relative almost maximal rigid object has exactly two non - isomorphic indecomposable complements. | arxiv:1907.09963 |
the advent of the internet era has led to an explosive growth in the electronic health records ( ehr ) in the past decades. the ehr data can be regarded as a collection of clinical events, including laboratory results, medication records, physiological indicators, etc, which can be used for clinical outcome prediction tasks to support constructions of intelligent health systems. learning patient representation from these clinical events for the clinical outcome prediction is an important but challenging step. most related studies transform ehr data of a patient into a sequence of clinical events in temporal order and then use sequential models to learn patient representations for outcome prediction. however, clinical event sequence contains thousands of event types and temporal dependencies. we further make an observation that clinical events occurring in a short period are not constrained by any temporal order but events in a long term are influenced by temporal dependencies. the multi - scale temporal property makes it difficult for traditional sequential models to capture the short - term co - occurrence and the long - term temporal dependencies in clinical event sequences. in response to the above challenges, this paper proposes a multi - level representation model ( mrm ). mrm first uses a sparse attention mechanism to model the short - term co - occurrence, then uses interval - based event pooling to remove redundant information and reduce sequence length and finally predicts clinical outcomes through long short - term memory ( lstm ). experiments on real - world datasets indicate that our proposed model largely improves the performance of clinical outcome prediction tasks using ehr data. | arxiv:1911.05698 |
charged lepton flavour violating transitions would be a clear signal of new physics beyond the standard model. their search has been carried out in a variety of channels, the most sensitive being those involving a muon : however no positive evidence has been found so far. the meg experiment has recently set the best limit on such processes by investigating the existence of the $ \ mu \ to e \ gamma $ decay. in the next decade several experiments are planned to pursue the search for $ \ mu \ to e \ gamma $, $ \ mu \ to eee $, $ \ mu \ to e $ conversion in nuclei, as well as on processes involving the $ \ tau $, to an unprecedented level of precision. in this review we want to give a pedagogical introduction on the theoretical motivations for such searches as well as on the experimental aspects upon which they are based. | arxiv:1709.00294 |
it is declared that the aim of simplifying representations of coefficients of power series of classical statistical mechanics is to simplify a process of obtaining estimates of the coefficients using their simplified representations. the aim of the article is : to formulate criteria for the complexity ( from the above point of view ) of these representations and to demonstrate their application by examples of comparing ree - hoover representations of virial coefficients and such representations of power series coefficients that are based on the conception of the frame classification of labeled graphs. to solve these problems, mathematical notions were introduced ( such as a base product, a base integral, a base linear combination of integrals, a base linear combination of integrals with coefficients of negligible complexity, a base set of base linear combinations of integrals with coefficients of negligible complexity ) ; and a classification of representations of coefficients of power series of classical statistical mechanics is proposed. in this classification the class of base linear combinations of integrals with coefficients of negligible complexity is the most important class. it includes the most well - known representations of the coefficients of power series of classical statistical mechanics. three criteria are formulated to estimate the comparative complexity of base linear combinations of integrals with coefficients of negligible complexity and their extensions to the totality of base sets of base linear combinations of integrals with coefficients of negligible complexity are constructed. the application of all the constructed criteria is demonstrated by examples of comparing with each other of the above power series coefficients representations. the obtained results are presented in the tables and commented. | arxiv:2207.07583 |
even though having more possession does not necessarily lead to winning, teams like manchester city, liverpool, and leeds united notably have tried to recover the ball quickly after they lost it over the past few years. nowadays, some of the top managers in the world apply high - pressing styles, and concepts such as the five - second rule, usually credited to guardiola, have been spreading out [ 9 ] [ 10 ], becoming a fundamental part of how lots of teams have played over the recent years. expressions like " don ' t let them breathe " and " get the ball back as soon as possible " are often heard in the media [ 4 ] [ 5 ] [ 6 ], but what are the actions that most lead to a change in possession? what is the influence of a team ' s positioning on the ball recovery? which are the players that more often collapse when under pressure? can we evaluate the defensive dynamics of teams that do not necessarily press the player in possession as intensely as those mentioned above? we try to answer those and other questions in this paper by creating a generalized action based ball recovery model ( gabr ) using statsbomb 360 $ ^ \ circ $ data. | arxiv:2307.04215 |
in this paper, we propose a cooperative approach to improve the security of both primary and secondary systems in cognitive radio multicast communications. during their access to the frequency spectrum licensed to the primary users, the secondary unlicensed users assist the primary system in fortifying security by sending a jamming noise to the eavesdroppers, while simultaneously protect themselves from eavesdropping. the main objective of this work is to maximize the secrecy rate of the secondary system, while adhering to all individual primary users ' secrecy rate constraints. in the case of passive eavesdroppers and imperfect channel state information knowledge at the transceivers, the utility function of interest is nonconcave and involved constraints are nonconvex, and thus, the optimal solutions are troublesome. to address this problem, we propose an iterative algorithm to arrive at a local optimum of the considered problem. the proposed iterative algorithm is guaranteed to achieve a karush - kuhn - tucker solution. | arxiv:1703.00147 |
we report results on superconducting tunneling spectroscopy of a carbon nanotube quantum dot. using a three - probe technique that includes a superconducting tunnel probe, we map out changes in conductance due to band structure, excited states, and end - to - end bias. the superconducting probe allows us to observe enhanced spectroscopic features, such as robust signals of both elastic and inelastic co - tunneling. we also see evidence of inelastic scattering processes inside the quantum dot. | arxiv:0907.2886 |
we describe a two - player non - local game, with a fixed small number of questions and answers, such that an $ \ epsilon $ - close to optimal strategy requires an entangled state of dimension $ 2 ^ { \ omega ( \ epsilon ^ { - 1 / 8 } ) } $. our non - local game is inspired by the three - player non - local game of ji, leung and vidick [ arxiv : 1802. 04926 ]. it reduces the number of players from three to two, as well as the question and answer set sizes. moreover, it provides an ( arguably ) elementary proof of the non - closure of the set of quantum correlations, based on embezzlement and self - testing. in contrast, previous proofs involved representation theoretic machinery for finitely - presented groups and $ c ^ * $ - algebras. | arxiv:1904.02350 |
let $ g $ be a transitive permutation group acting on a finite set $ \ omega $ with $ | \ omega | \ geqslant 2 $. an element of $ g $ is said to be a derangement if it has no fixed points on $ \ omega $, and by a theorem of jordan from 1872, $ g $ always contains such an element. in particular by a theorem of fein, kantor and schacher $ g $ contains a derangement of prime power order. nevertheless there exist groups in which there are no derangements of prime order, these groups are called elusive groups. defining an natural extension of this we say $ g $ is almost elusive if it contains a unique conjugacy class of derangements of prime order. in recent work with burness, we reduced the problem of determining the almost elusive quasiprimitive groups to the almost simple and 2 - transitive affine cases. additionally we classified the primitive almost elusive almost simple groups with socle an alternating group, a sporadic group or a group of lie type with ( twisted ) lie rank equal to 1. in this paper we complete the classification of the primitive almost elusive almost simple classical groups. | arxiv:2108.10190 |
a strong coupling between electric polarization and elastic deformation in solids is an important factor in creating useful electromechanical nanodevices. such coupling is typically allowed in insulating materials with inversion symmetry breaking as exemplified by the piezoelectric effect in ferroelectric materials. therefore, materials with metallicity and centrosymmetry have tended to be out of scope in this perspective. here, we report the observation of giant elastic deformation by the application of an alternating electric current in topological semimetals ( v, mo ) te2, regardless of the centrosymmetry. considering the crystal and band structures and the asymmetric measurement configurations in addition to the absence of the electromechanical effect in a trivial semimetal tite2, the observed effect is discussed in terms of a berry - phase - derived converse flexoelectric effect in metals. the observation of the flexoelectric effect in topological semimetals paves a way for a new type of nanoscale electromechanical sensors and energy harvesting. | arxiv:2410.04831 |
memory bound functions have been proposed for fighting spam, resisting sybil attacks and other purposes. a particular implementation of such functions has been proposed in which the average effort required to generate a proof of effort is set by parameters e and l to e * l. the distribution of effort required to generate an individual proof about this average is fairly broad. when particular uses of these functions are envisaged, the choice of e and l, and the system design surrounding the generation and verification of proofs of effort, need to take the breadth of the distribution into account. we show the distribution for this implementation, discuss the system design issues in the context of two proposed applications, and suggest an improved implementation. | arxiv:cs/0311005 |
zero - shot learning ( zsl ) aims to infer novel classes without training samples by transferring knowledge from seen classes. existing embedding - based approaches for zsl typically employ attention mechanisms to locate attributes on an image. however, these methods often ignore the complex entanglement among different attributes ' visual features in the embedding space. additionally, these methods employ a direct attribute prediction scheme for classification, which does not account for the diversity of attributes in images of the same category. to address these issues, we propose a novel dual feature augmentation network ( dfan ), which comprises two feature augmentation modules, one for visual features and the other for semantic features. the visual feature augmentation module explicitly learns attribute features and employs cosine distance to separate them, thus enhancing attribute representation. in the semantic feature augmentation module, we propose a bias learner to capture the offset that bridges the gap between actual and predicted attribute values from a dataset ' s perspective. furthermore, we introduce two predictors to reconcile the conflicts between local and global features. experimental results on three benchmarks demonstrate the marked advancement of our method compared to state - of - the - art approaches. our code is available at https : / / github. com / sion1 / dfan. | arxiv:2309.13833 |
github is a popular data repository for code examples. it is being continuously used to train several ai - based tools to automatically generate code. however, the effectiveness of such tools in correctly demonstrating the usage of cryptographic apis has not been thoroughly assessed. in this paper, we investigate the extent and severity of misuses, specifically caused by incorrect cryptographic api call sequences in github. we also analyze the suitability of github data to train a learning - based model to generate correct cryptographic api call sequences. for this, we manually extracted and analyzed the call sequences from github. using this data, we augmented an existing learning - based model called deepapi to create two security - specific models that generate cryptographic api call sequences for a given natural language ( nl ) description. our results indicate that it is imperative to not neglect the misuses in api call sequences while using data sources like github, to train models that generate code. | arxiv:2211.13498 |
in this paper, as a common generalization of $ si _ { 2 } $ - continuous spaces and $ s _ { 2 } $ - quasicontinuous posets, we introduce the concepts of $ si _ { 2 } $ - quasicontinuous spaces and $ \ mathcal { gd } $ - convergence of nets for arbitrary topological spaces by the cuts. some characterizations of $ si _ { 2 } $ - quasicontinuity of spaces are given. the main results are : ( 1 ) a space is $ si _ { 2 } $ - quasicontinuous if and only if its weakly irreducible topology is hypercontinuous under inclusion order ; ( 2 ) a $ t _ { 0 } $ space $ x $ is $ si _ { 2 } $ - quasicontinuous if and only if the $ \ mathcal { gd } $ - convergence in $ x $ is topological. | arxiv:2211.12317 |
a new structural phase transition has been observed at low temperatures for the one third of a monolayer ( alpha phase ) of pb on ge ( 111 ) using a variable - temperature scanning tunneling microscope. the well - known ( r3xr3 ) r30 to ( 3x3 ) transition is accompanied by a new structural phase transition from ( 3x3 ) to a disordered phase at ~ 76 k. the formation of the new disordered phase is incompatible with the belief that the ( 3x3 ) phase is the ground state. the mechanism of the phase transition in this triangular lattice can be mapped onto antiferromagnetic spin ising model, with the geometric frustration. | arxiv:cond-mat/0407674 |
decentralized federated learning ( dfl ) enables clients ( e. g., hospitals and banks ) to jointly train machine learning models without a central orchestration server. in each global training round, each client trains a local model on its own training data and then they exchange local models for aggregation. in this work, we propose selfishattack, a new family of attacks to dfl. in selfishattack, a set of selfish clients aim to achieve competitive advantages over the remaining non - selfish ones, i. e., the final learnt local models of the selfish clients are more accurate than those of the non - selfish ones. towards this goal, the selfish clients send carefully crafted local models to each remaining non - selfish one in each global training round. we formulate finding such local models as an optimization problem and propose methods to solve it when dfl uses different aggregation rules. theoretically, we show that our methods find the optimal solutions to the optimization problem. empirically, we show that selfishattack successfully increases the accuracy gap ( i. e., competitive advantage ) between the final learnt local models of selfish clients and those of non - selfish ones. moreover, selfishattack achieves larger accuracy gaps than poisoning attacks when extended to increase competitive advantages. | arxiv:2310.13862 |
let $ u $ and $ v $ be two independent $ n $ by $ n $ random matrices that are distributed according to haar measure on $ u ( n ) $. let $ \ sigma $ be a non - negative deterministic $ n $ by $ n $ matrix. the single ring theorem [ 26 ] asserts that the empirical eigenvalue distribution of the matrix $ x : = u \ sigma v ^ * $ converges weakly, in the limit of large $ n $, to a deterministic measure which is supported on a single ring centered at the origin in $ \ mathbb { c } $. within the bulk regime, i. e. in the interior of the single ring, we establish the convergence of the empirical eigenvalue distribution on the optimal local scale of order $ n ^ { - 1 / 2 + \ varepsilon } $ and establish the optimal convergence rate. the same results hold true when ~ $ u $ and ~ $ v $ are haar distributed on $ o ( n ) $. | arxiv:1612.05920 |
in this paper the theory of time - dependent and time - independent canonical transformations is considered from a geometric perspective. both the geometric formalism and the coordinate based approach are described in detail. in particular, one - parameter groups of canonical transformations are geometrically identified with flows of hamiltonian vector fields which, in turn, are their infinitesimal generators. likewise, infinitesimal generators of invariance transformations are geometrically characterized. the main results are established in the form of theorems and the connection between the geometric and the coordinate based frameworks is remarked using concrete examples. | arxiv:2409.18848 |
we present all two - loop five - parton leading - colour finite remainders in the spinor - helicity formalism by analysing numerical evaluations of their known expressions in terms of mandelstam invariants. recasting them in terms of spinor - helicity variables allows us to obtain expressions which are more compact, faster to evaluate, numerically more stable and manifestly free from poles of higher order than necessary. at the same time, due to the better scaling of our reconstruction strategy with the complexity of the input, we required one order of magnitude fewer numerical samples to complete the analytical reconstruction than were needed by the authors of ref. \ cite { abreu : 2019odu }, albeit using higher numerical working precision. this places our reconstruction technique as an alternative to the finite - field single - numerator reconstruction for future applications. | arxiv:2010.14525 |
we present ordinary differential equation variational auto - encoder ( ode $ ^ 2 $ vae ), a latent second order ode model for high - dimensional sequential data. leveraging the advances in deep generative models, ode $ ^ 2 $ vae can simultaneously learn the embedding of high dimensional trajectories and infer arbitrarily complex continuous - time latent dynamics. our model explicitly decomposes the latent space into momentum and position components and solves a second order ode system, which is in contrast to recurrent neural network ( rnn ) based time series models and recently proposed black - box ode techniques. in order to account for uncertainty, we propose probabilistic latent ode dynamics parameterized by deep bayesian neural networks. we demonstrate our approach on motion capture, image rotation and bouncing balls datasets. we achieve state - of - the - art performance in long term motion prediction and imputation tasks. | arxiv:1905.10994 |
the lasso is a popular method to induce shrinkage and sparsity in the solution vector ( coefficients ) of regression problems, particularly when there are many predictors relative to the number of observations. solving the lasso in this high - dimensional setting can, however, be computationally demanding. fortunately, this demand can be alleviated via the use of screening rules that discard predictors prior to fitting the model, leading to a reduced problem to be solved. in this paper, we present a new screening strategy : look - ahead screening. our method uses safe screening rules to find a range of penalty values for which a given predictor cannot enter the model, thereby screening predictors along the remainder of the path. in experiments we show that these look - ahead screening rules outperform the active warm - start version of the gap safe rules. | arxiv:2105.05648 |
the nonlinear diffusion equation $ u _ t = ( u ^ { - 4 / 3 } u _ x ) _ x $ is reduced by the substitution $ u = v ^ { - 3 / 4 } $ to an equation with quadratic nonlinearities possessing a polynomial invariant linear subspace of the maximal possible dimension equal to five. the dynamics of the solutions on this subspace is described by a fifth - order nonlinear dynamical system ( v. a. galaktionov ). we found that, on differentiation, this system reduces to a single linear equation of the second order, which is a special case of the lam \ ' e equation, and that the general solution of this linear equation is expressed in terms of the weierstrass $ \ wp $ - function and its derivative. as a result, all exact solutions $ v ( x, t ) $ on a five - dimensional polynomial invariant subspace, as well as the corresponding solutions $ u ( x, t ) $ of the original equation, are constructed explicitly. using invariance condition, two families of non - invariant solutions are singled out. for one of these families, all types of solutions are considered in detail. some of them describe peculiar blow - up regimes, while others fade out in finite time. | arxiv:2109.10786 |
we study the physical - layer security of a multiple source - destination ( sd ) pairs coexisting wireless network in the face of an eavesdropper, where an eavesdropper intends to wiretap the signal transmitted by the sd pairs. in order to protect the wireless transmission against eavesdropping, we propose a cooperation framework relying on two stages. specifically, an sd pair is selected to access the total allocated spectrum using an appropriately designed scheme at the beginning of the first stage. the other source nodes ( sns ) simultaneously transmit their data to the sn of the above - mentioned sd pair relying on an orthogonal way during the first stage. then, the sn of the chosen sd pair transmits the data packets containing its own messages and the other sns ' messages to its dedicated destination node ( dn ) in the second stage, which in turn will forward all the other dns ' data to the application center via the core network. we conceive a specific sd pair selection scheme, termed as the transmit antenna selection aided source - destination pair selection ( tas - sdps ). we derive the secrecy outage probability ( sop ) expressions for the tas - sdps, as well as for the conventional round - robin source - destination pair selection ( rsdps ) and non - cooperative ( non - coop ) schemes for comparison purposes. furthermore, we carry out the secrecy diversity gain analysis in the high main - to - eavesdropper ratio ( mer ) region, showing that the tas - sdps scheme is capable of achieving the maximum attainable secrecy diversity order. | arxiv:1901.10095 |
in this paper, we propose and compare two spectral angle based approaches for spatial - spectral classification. our methods use the spectral angle to generate unary energies in a grid - structured markov random field defined over the pixel labels of a hyperspectral image. the first approach is to use the exponential spectral angle mapper ( esam ) kernel / covariance function, a spectral angle based function, with the support vector machine and the gaussian process classifier. the second approach is to directly use the minimum spectral angle between the test pixel and the training pixels as the unary energy. we compare the proposed methods with the state - of - the - art markov random field methods that use support vector machines and gaussian processes with squared exponential kernel / covariance function. in our experiments with two datasets, it is seen that using minimum spectral angle as unary energy produces better or comparable results to the existing methods at a smaller running time. | arxiv:1610.06985 |
we propose a counterfactual approach to train ` ` causality - aware " predictive models that are able to leverage causal information in static anticausal machine learning tasks ( i. e., prediction tasks where the outcome influences the features ). in applications plagued by confounding, the approach can be used to generate predictions that are free from the influence of observed confounders. in applications involving observed mediators, the approach can be used to generate predictions that only capture the direct or the indirect causal influences. mechanistically, we train supervised learners on ( counterfactually ) simulated features which retain only the associations generated by the causal relations of interest. we focus on linear models, where analytical results connecting covariances, causal effects, and prediction mean squared errors are readily available. quite importantly, we show that our approach does not require knowledge of the full causal graph. it suffices to know which variables represent potential confounders and / or mediators. we discuss the stability of the method with respect to dataset shifts generated by selection biases and validate the approach using synthetic data experiments. | arxiv:2001.03998 |
anomaly detection is the practice of identifying items or events that do not conform to an expected behavior or do not correlate with other items in a dataset. it has previously been applied to areas such as intrusion detection, system health monitoring, and fraud detection in credit card transactions. in this paper, we describe a new method for detecting anomalous behavior over network performance data, gathered by perfsonar, using two machine learning algorithms : boosted decision trees ( bdt ) and simple feedforward neural network. the effectiveness of each algorithm was evaluated and compared. both have shown sufficient performance and sensitivity. | arxiv:1801.10094 |
in this paper, we establish the quasi - compactness of the transfer operator associated with skew product systems that are semi - conjugate to piecewise convex maps with a countably infinite number of branches. these non - invertible skew products admit discontinuities, with the critical set confined to a countable collection of fibers. furthermore, we demonstrate that such systems possess an invariant measure whose disintegration along the fibers exhibits bounded variation, a concept introduced and developed in this work. | arxiv:2502.08751 |
we study the system of multi color - flux - tubes in terms of the dual ginzburg - landau theory. we consider two ideal cases, where the directions of all the color - flux - tubes are the same in one case and alternative in the other case for neighboring flux - tubes. we formulate the system of multi color - flux - tubes by regarding it as the system of two color - flux - tubes penetrating through a two dimensional sphere surface. we find the multi flux - tube configuration becomes uniform above some critical flux - tube number density $ \ rho _ c = 1. 3 \ sim 1. 7 { \ rm fm } ^ { - 2 } $. on the other hand, the inhomogeneity on the color electric distribution appears when the flux - tube density is smaller than $ \ rho _ c $. we discuss the relation between the inhomogeneity in the color - electric distribution and the flux - tube number density in the multi - flux - tube system created during the qgp formation process in the ultra - relativistic heavy - ion collision. | arxiv:hep-ph/9602412 |
quantum convolutional neural networks ( qcnns ) have been introduced as classifiers for gapped quantum phases of matter. here, we propose a model - independent protocol for training qcnns to discover order parameters that are unchanged under phase - preserving perturbations. we initiate the training sequence with the fixed - point wavefunctions of the quantum phase and then add translation - invariant noise that respects the symmetries of the system to mask the fixed - point structure on short length scales. we illustrate this approach by training the qcnn on phases protected by time - reversal symmetry in one dimension, and test it on several time - reversal symmetric models exhibiting trivial, symmetry - breaking, and symmetry - protected topological order. the qcnn discovers a set of order parameters that identifies all three phases and accurately predicts the location of the phase boundary. the proposed protocol paves the way towards hardware - efficient training of quantum phase classifiers on a programmable quantum processor. | arxiv:2211.11786 |
comprehensive 3d scene understanding, both geometrically and semantically, is important for real - world applications such as robot perception. most of the existing work has focused on developing data - driven discriminative models for scene understanding. this paper provides a new approach to scene understanding, from a synthesis model perspective, by leveraging the recent progress on implicit 3d representation and neural rendering. building upon the great success of neural radiance fields ( nerfs ), we introduce scene - property synthesis with nerf ( ss - nerf ) that is able to not only render photo - realistic rgb images from novel viewpoints, but also render various accurate scene properties ( e. g., appearance, geometry, and semantics ). by doing so, we facilitate addressing a variety of scene understanding tasks under a unified framework, including semantic segmentation, surface normal estimation, reshading, keypoint detection, and edge detection. our ss - nerf framework can be a powerful tool for bridging generative learning and discriminative learning, and thus be beneficial to the investigation of a wide range of interesting problems, such as studying task relationships within a synthesis paradigm, transferring knowledge to novel tasks, facilitating downstream discriminative tasks as ways of data augmentation, and serving as auto - labeller for data creation. | arxiv:2206.04669 |
affordance refers to the functional properties that an agent perceives and utilizes from its environment, and is key perceptual information required for robots to perform actions. this information is rich and multimodal in nature. existing multimodal affordance methods face limitations in extracting useful information, mainly due to simple structural designs, basic fusion methods, and large model parameters, making it difficult to meet the performance requirements for practical deployment. to address these issues, this paper proposes the bit - align image - depth - text affordance mapping framework. the framework includes a bypass prompt module ( bpm ) and a text feature guidance ( tfg ) attention selection mechanism. bpm integrates the auxiliary modality depth image directly as a prompt to the primary modality rgb image, embedding it into the primary modality encoder without introducing additional encoders. this reduces the model ' s parameter count and effectively improves functional region localization accuracy. the tfg mechanism guides the selection and enhancement of attention heads in the image encoder using textual features, improving the understanding of affordance characteristics. experimental results demonstrate that the proposed method achieves significant performance improvements on public agd20k and hico - iif datasets. on the agd20k dataset, compared with the current state - of - the - art method, we achieve a 6. 0 % improvement in the kld metric, while reducing model parameters by 88. 8 %, demonstrating practical application values. the source code will be made publicly available at https : / / github. com / dawdse / bit - align. | arxiv:2503.02600 |
we obtain from the quark - gluon dynamics, the gell ' mann - ne ' eman eightfold way baryons in an imaginary - time functional integral formulation of 3 + 1 lattice qcd in the strong coupling regime ( small hopping parameter $ \ kappa > 0 $ ). the model has $ { \ rm su } ( 3 ) _ c $ gauge and global $ { \ rm su } ( 3 ) _ f $ flavor symmetries. in the subspace of the physical hilbert space of vectors with an odd number of quarks, the baryons are associated with isolated dispersion curves in the energy - momentum spectrum. the spin 1 / 2 octet and spin 3 / 2 decuplet baryons have asymptotic mass $ - 3 \ ln \ kappa $ and for each baryon there is an antibaryon with identical spectral properties. all the masses have the form $ m = - 3 \ ln \ kappa - 3 \ kappa ^ 3 / 4 + \ kappa ^ 6 r ( \ kappa ) $, with $ r ( \ kappa ) $ real analytic. for each member of the octet $ r ( \ kappa ) $ is the same ; for each member of the decuplet, $ r ( 0 ) $ is the same. so, there is no mass splitting within the octet, and within the decuplet up to and including $ { \ cal o } ( \ kappa ^ 6 ) $. however, there is an octet - decuplet mass difference of $ 3 \ kappa ^ 6 / 4 + { \ cal o } ( \ kappa ^ 7 ) $. the baryon and antibaryon spectrum is the only one up to near the meson - baryon threshold of nearly $ - 5 \ ln \ kappa $. a decoupling of hyperplane method is used to naturally unveil the form of the baryon composite fields ( no a priori guesswork ), to show the existence of particles and their multiplicities using a spectral representation for the two - baryon correlation. we also obtain the ( anti - ) baryon dispersion curves which admit the representation $ w ( \ kappa, \ vec p ) = - 3 \ ln \ kappa - 3 \ kappa ^ 3 / 4 + \ kappa ^ 3 \ sum _ { j = 1, 2, 3 } ( 1 - \ cos ^ j ) / 4 + r ( \ kappa, \ vec p | arxiv:0707.1677 |
we prove an identity about partitions, previously conjectured in the study of shifted jack polynomials ( math. co / 9903020 ). the proof given is using $ \ lambda $ - ring techniques. it would be interesting to obtain a bijective proof. | arxiv:math/0001082 |
we recently formulated the canonical boundary - value problem of propagation of surface plasmon - polariton ( spp ) waves along the direction of periodicity of a one - dimensional photonic crystal. here we present the general formulation of that canonical problem supporting the oblique propagation of spp waves in the interface plane. the general dispersion equation has been obtained using the rigorous coupled - wave approach for the oblique propagation and numerically solved using the muller ' s method. a periodicity in the wavenumbers of the spp waves was observed. furthermore, the regions of high losses for the spp waves, dubbed as plasmonic bandgaps, were observed in the photonic band diagram of the spp waves. these plasmonic bandgaps can be used to construct optical filters for the spp waves. | arxiv:1907.08861 |
in this paper, we propose a novel cloud - native architecture for collaborative agentic network slicing. our approach addresses the challenge of managing shared infrastructure, particularly cpu resources, across multiple network slices with heterogeneous requirements. each network slice is controlled by a dedicated agent operating within a dockerized environment, ensuring isolation and scalability. the agents dynamically adjust cpu allocations based on real - time traffic demands, optimizing the performance of the overall system. a key innovation of this work is the development of emergent communication among the agents. through their interactions, the agents autonomously establish a communication protocol that enables them to coordinate more effectively, optimizing resource allocations in response to dynamic traffic demands. based on synthetic traffic modeled on real - world conditions, accounting for varying load patterns, tests demonstrated the effectiveness of the proposed architecture in handling diverse traffic types, including embb, urllc, and mmtc, by adjusting resource allocations to meet the strict requirements of each slice. additionally, the cloud - native design enables real - time monitoring and analysis through prometheus and grafana, ensuring the system ' s adaptability and efficiency in dynamic network environments. the agents managed to learn how to maximize the shared infrastructure with a conflict rate of less than 3 %. | arxiv:2502.10775 |
software - defined networking ( sdn ) has shifted network management by decoupling the data and control planes. this enables programmatic control via software applications using open apis. sdn ' s programmability has fueled its popularity but may have opened issues extending the attack surface by introducing vulnerable software. therefore, the research community needs to have a deep and broad understanding of the risks posed by sdn to propose mitigating measures. the literature, however, lacks a comprehensive review of the current state of research in this direction. this paper addresses this gap by providing a comprehensive overview of the state - of - the - art research in sdn security focusing on the software ( i. e., the controller, apis, applications ) part. we systematically reviewed 58 relevant publications to analyze trends, identify key testing and analysis methodologies, and categorize studied vulnerabilities. we further explore areas where the research community can make significant contributions. this work offers the most extensive and in - depth analysis of sdn software security to date. | arxiv:2502.13828 |
starting from a real analytic conformal cartan connection on a real analytic surface $ s $, we construct a complex surface $ t $ containing a family of pairs of projective lines. using the structure on $ s $ we also construct a complex $ 3 $ - space $ z $, such that $ z $ is a twistor space of a self - dual conformal $ 4 $ - fold and $ t $ is a quotient of $ z $ by a holomorphic local $ \ mathbb { c } ^ * $ action. we prove that $ t $ is a minitwistor space of an asymptotically hyperbolic einstein - weyl space with $ s $ as an asymptotic boundary. | arxiv:1312.0122 |
we ascribe the twin kilohertz quasi periodic oscillations ( khz qpos ) of x - ray spectra of low mass x - ray binaries ( lmxbs ) to the pseudo - newtonian keplerian frequency and the apogee and perigee precession frequency of the same matter in the inner disk, and ascribe 15 - 60 hz qpo ( hbo ) to the apogee ( or perigee ) precession and its second harmonic frequency to both apogee and perigee precession in the outer disk boundary of the neutron star ( ns ) magnetosphere. the radii of the inner and outer disks are correlated each other by a factor of two is assumed. the obtained conclusions include : all qpo frequencies increase and frequency difference of twin khz qpos decreases with increasing the accretion rate. the obtained theoretical relations between hbo frequency and twin khz qpos are simlilar to the measured empirical formula. further, the theoretical formula to calculate the ns mass by the twin khz qpos is proposed, and the resultant values are in the range of 1. 4 to 1. 8 solar masses. qpos from lmxbs likely provide an accurate laboratory for a strong gravitational field, by which a new method to determine the ns masses of lmxbs is suggested. | arxiv:astro-ph/9911279 |
the main subject of this paper is the mean - value of the function $ | \ zeta ( s ) | ^ { 2k - 1 } $ in the critical strip. on lindel \ " of hypothesis we give a solution to this question for some class of disconnected sets. this paper is english version of our paper \ cite { 5 }. | arxiv:1501.03325 |
using the method of energy - level statistics, the localization properties of electrons moving in two dimensions in the presence of a perpendicular random magnetic field and additional random disorder potentials are investigated. for this model, extended states have recently been proposed to exist in the middle of the band. in contrast, from our calculations of the large - $ s $ behavior of the nearest neighbor level spacing distribution $ p ( s ) $ and from a finite size scaling analysis we find only localized states in the suggested energy and disorder range. | arxiv:cond-mat/9710011 |
we compute several coefficients needed for o ( a ) improvement of currents in perturbation theory, using the brodsky - lepage - mackenzie prescription for choosing an optimal scale q *. we then compare the results to non - perturbative calculations. normalization factors of the vector and axial vector currents show good agreement, especially when allowing for small two - loop effects. on the other hand, there are large discrepancies in the coefficients of o ( a ) improvement terms. we suspect that they arise primarily from power corrections inherent in the non - perturbative methods. | arxiv:hep-lat/0208004 |
this paper presents a patch - wise low - rank based image denoising method with constrained variational model involving local and nonlocal regularization. on one hand, recent patch - wise methods can be represented as a low - rank matrix approximation problem whose convex relaxation usually depends on nuclear norm minimization ( nnm ). here, we extend the nnm to the nonconvex schatten p - norm minimization with additional weights assigned to different singular values, which is referred to as the weighted schatten p - norm minimization ( wsnm ). an efficient algorithm is also proposed to solve the wsnm problem. the proposed wsnm not only gives better approximation to the original low - rank assumption, but also considers physical meanings of different data components. on the other hand, due to the naive aggregation schema which integrates all the denoised patches into a whole image, current patch - wise denoising methods always produce various degree of artifacts in denoised results. therefore, to further reduce artifacts, a data - driven regularizer called steering total variation ( stv ) combined with nonlocal tv is derived for a variational model, which imposes local and nonlocal consistency constraints on the patch - wise denoised image. a highly simple but efficient algorithm is proposed to solve this variational model with convergence guarantee. both wsnm and local \ & nonlocal consistent regularization are integrated into an iterative restoration framework to produce final results. extensive experimental testing shows, both qualitatively and quantitatively, that the proposed method can effectively remove noise, as well as reduce artifacts compared with state - of - the - art methods. | arxiv:1501.01372 |
the convergence of energy transmission and data communication has become a key feature of decentralized energy systems across a broad spectrum of voltage / power ranges, including smart grid applications and cyber - physical power systems. this paper compares two distinct approaches : power line communications ( plc ) and talkative power conversion ( tpc ). while plc leverages existing power infrastructure for data transmission by using external data transmitters and receivers, tpc integrates communication capabilities directly into power electronic converters. we present their technical foundations and applications, benchmark their strengths and bottlenecks, and outline future research directions regarding tpc that could bridge the gap between power and communication technologies. | arxiv:2504.12015 |
taking up a variational viewpoint, we present some nonlocal - to - local asymptotic results for various kinds of integral functionals. the content of the thesis comprises the contributions first appeared in some research papers in collaboration with j. berendsen, a. cesaroni, a. chambolle, and m. novaga. | arxiv:2004.03565 |
monochromatic photons could be produced in the annihilation or decay of dark matter particles. at high energies, the search for such line features in the cosmic gamma - ray spectrum is essentially background free because plausible astrophysical processes are not expected to produce such a signal. the observation of a gamma - ray line would hence be a ` smoking - gun ' signature for dark matter, making the search for such signals particularly attractive. among the different dark matter models predicting gamma - ray lines, the local supersymmetric extension of the standard model with small r - parity violation and gravitino lsp is of particular interest because it provides a framework where primordial nucleosynthesis, gravitino dark matter and thermal leptogenesis are naturally consistent. using the two - years fermi lat data, we present a dedicated search for gamma - ray lines coming from dark matter annihilation or decay in the galactic halo. taking into account the full detector response, and using a binned profile likelihood method, we search for significant line features in the energy spectrum of the diffuse flux observed in different regions of the sky. no evidence for a line signal at the 5 - sigma level is found for photon energies between 1 and 300 gev, and conservative bounds on dark matter decay rates and annihilation cross sections are presented. implications for gravitino dark matter in presence of small r - parity violation are discussed, as well as the impact of our results on the prospect for seeing long - lived neutralinos or staus at the lhc. | arxiv:1101.2610 |
background : since their discovery by karl langer in the 19th century, skin tension lines ( stls ) have been used by surgeons to decide the location and orientation of an incision. although these lines are patient - specific, most surgeons rely on generic maps to determine their orientation. beyond the imprecise pinch test, there remains no accepted method for determining stls in vivo. methods : ( i ) the speed of an elastic motion travelling radially on the skin of canine cadavers was measured with a commercial device called the reviscometer. ( ii ) similar to the original experiments conducted by karl langer, circular excisions were made on the skin and the geometric changes to the resulting wounds and excised samples were used to determine the orientation of stls. results : a marked anisotropy in the speed of the elastic wave travelling radially was observed. the orientation of the fastest wave was found to correlate with the orientation of the elongated wound ( p < 0. 001, r ^ 2 = 74 % ). similarly, the orientation of fastest wave was the same for both in vivo and excised isolated samples, indicating that the stls have a structural basis. resulting wounds expanded by an average area of 9 % ( + 16 % along stl and - 10 % across ) while excised skin shrunk by an average area of 33 % ( 23 % along stl and 10 % across ). conclusion : elastic surface wave propagation has been validated experimentally as a robust method for determining the orientation of stls non - destructively and non - invasively. this study has implications for the identification of stls and for the prediction of skin tension levels, both important factors in both human and veterinary reconstructive surgery. | arxiv:1609.07267 |
pion dissociation in a medium of hot quark matter is studied. the decay width of pion is found to be large but finite at temperatures much higher than the so called critical temperature of chiral or deconfinement transition. consequently, pions should coexist with quarks and gluons at such high temperatures. the result is in agreement with the lattice calculations. the implication of the above result in the study of quark - gluon plasma is discussed. | arxiv:nucl-th/9803004 |
the formation of objects below or close to the hydrogen burning limit is currently vividly discussed and is one of the main open issues in the field of the origins of stars and planets. applying various observational techniques, we explored a sample of brown dwarfs and very low - mass stars in the chai star forming cloud at an age of only a few million years and determined fundamental parameters for their formation and early evolution. tracking the question of how frequent are brown dwarf binaries and if brown dwarfs have planets, one of the first radial velocity ( rv ) surveys of brown dwarfs sensitive down to planetary masses is carried out based on high - resolution spectra taken with uves at the vlt. the results hint at a low multiplicity fraction, which is in contrast to the situation for young low - mass stars. testing recent formation scenarios, which propose an ejection out of the birth place in the early accretion phase, we carried out a precise kinematic analysis of the brown dwarfs in our sample in comparison with t tauri stars in the same field. this yielded the first empirical upper limit for possible ejection velocities of a homogeneous group of brown dwarfs. rotation is a fundamental parameter for objects in this early evolutionary phase. by means of studying the line broadening of spectral features in the uves spectra as well as by tracing rotational modulation of their lightcurves due to surface spots in photometric monitoring data, one of the first rotation rates of very young brown dwarfs have been determined. in the light of the presented observational results, the current scenarios for the formation of brown dwarfs are discussed. | arxiv:astro-ph/0501220 |
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