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science of science policy ( sosp ) is an emerging interdisciplinary research area that seeks to develop theoretical and empirical models of the scientific enterprise. this scientific basis can be used to help government, and society in general, make better r & d management decisions by establishing a scientifically rigorous, quantitative basis from which policy makers and researchers may assess the impacts of the nation ' s scientific and engineering enterprise, improve their understanding of its dynamics, and assess the likely outcomes. examples of research in the science of science policy include models to understand the production of science, qualitative, quantitative and computational methods to estimate the impact of science, and processes for choosing from alternative science portfolios. : 5 = = federal sosp effort = = the federal government of the united states has long been a supporter of sosp. in 2006, in response to office of science and technology policy director john h. marburger ' s challenge for a new " science of science policy, " the national science and technology council ' s subcommittee on social, behavioral and economic sciences ( sbe ) established an interagency task group on science of science policy ( itg ) to serve as part of the internal deliberative process of the subcommittee. in 2008, the sosp itg developed and published the science of science policy : a federal research roadmap, which outlined the federal efforts necessary for the long - term development of a science of science policy, and presented this roadmap to the sosp community. the itg ' s subsequent work has been guided by the questions outlined in the roadmap and the action steps developed at the workshop. furthermore, since 2007, the national science foundation, in support of academic research to advance the field, has awarded grants from the science of science and innovation policy ( scisip ) program. the scisip research supports and complements the federal sosp efforts by providing new tools with immediate relevance to policymakers. = = science of science and innovation policy program = = the science of science and innovation policy ( scisip ) program was established at the national science foundation in 2005 in response to a call from john marburger for a " specialist scholarly community " to study the science of science policy. the program has three major goals : advancing evidence - based science and innovation policy decision making ; building a scientific community to study science and innovation policy ; and leveraging the experience of other countries. between 2007 and 2011, over one hundred and thirty awards were made in five rounds of funding. the awardees include economists, sociologists | https://en.wikipedia.org/wiki/Science_of_science_policy |
answering a question of randal - williams, we show the natural maps from split steinberg modules of a dedekind domain to the associated steinberg modules are surjective. | arxiv:2407.18208 |
we measured the temperature dependence of the 1st and the 3rd harmonics of the ac magnetic susceptibility on some type ii superconducting samples at different ac field amplitudes, hac. in order to interpret the measurements, we computed the harmonics of the ac susceptibility as function of the temperature t, by integrating the non - linear diffusion equation for the magnetic field with different creep models, namely the vortex glass - collective creep ( single - vortex, small bundle and large bundle ) and kim - anderson model. we also computed them by using a non - linear phenomenological i - v characteristics, including a power law dependence of the pinning potential on hac. our experimental results were compared with the numerically computed ones, by the analysis of the cole - cole plots. this method results more sensitive than the separate component analysis, giving the possibility to obtain detailed information about the contribution of the flux dynamic regimes in the magnetic response of the analysed samples. | arxiv:cond-mat/0309333 |
thermodynamic properties of a spin ice model on a kagom \ ' e lattice are obtained from dynamic simulations and compared with properties in square lattice spin ice. the model assumes three - component heisenberg - like dipoles of an array of planar magnetic islands situated on a kagom \ ' e lattice. ising variables are avoided. the island dipoles interact via long - range dipolar interactions and are restricted in their motion due to local shape anisotropies. we define various order parameters and obtain them and thermodynamic properties from the dynamics of the system via a langevin equation, solved by the heun algorithm. generally, a slow cooling from high to low temperature does not lead to a particular state of order, even for a set of coupling parameters that gives well thermalized states and dynamics. some suggestions are proposed for the alleviation of the geometric frustration effects and for the generation of local order in the low temperature regime. | arxiv:1407.4438 |
in this paper we introduce the $ ( n + 2 ) $ - dimensional born - infeld action with a dual field strength $ \ tilde { h } $. we compute the field equation by using schur polynomials and give a soliton solution. | arxiv:hep-th/9712002 |
in a 4 - manifold, the composition of a riemannian einstein metric with an almost paracomplex structure that is isometric and parallel, defines a neutral metric that is conformally flat and scalar flat. in this paper, we study hypersurfaces that are null with respect to this neutral metric and in particular we study their geometric properties with respect to the einstein metric. firstly, we show that all totally geodesic null hypersurfaces are scalar flat and their existence implies that the einstein metric in the ambient manifold must be ricci - flat. then, we find a necessary condition for the existence of null hypersurface with equal non - trivial principal curvatures and finally, we give a necessary condition on the ambient scalar curvature, for the existence of null ( non - minimal ) hypersurfaces that are of constant mean curvature. | arxiv:2212.10679 |
we use a schr \ " odinger wave equation formalism to solve the eikonal equation. in our framework, a solution to the eikonal equation is obtained in the limit as planck ' s constant $ \ hbar $ ( treated as a free parameter ) tends to zero of the solution to the corresponding linear schr \ " odinger equation. the schr \ " odinger equation corresponding to the eikonal turns out to be a \ emph { generalized, screened poisson equation }. despite being linear, it does not have a closed - form solution for arbitrary forcing functions. we present two different techniques to solve the screened poisson equation. in the first approach we use a standard perturbation analysis approach to derive a new algorithm which is guaranteed to converge provided the forcing function is bounded and positive. the perturbation technique requires a sequence of discrete convolutions which can be performed in $ o ( n \ log n ) $ using the fast fourier transform ( fft ) where $ n $ is the number of grid points. in the second method we discretize the linear laplacian operator by the finite difference method leading to a sparse linear system of equations which can be solved using the plethora of sparse solvers. the eikonal solution is recovered from the exponent of the resultant scalar field. our approach eliminates the need to explicitly construct viscosity solutions as customary with direct solutions to the eikonal. since the linear equation is computed for a small but non - zero $ \ hbar $, the obtained solution is an approximation. though our solution framework is applicable to the general class of eikonal problems, we detail specifics for the popular vision applications of shape - from - shading, vessel segmentation, and path planning. | arxiv:1403.1937 |
the international height reference system ( ihrs ) adopted by the iag in 2015 contains two novelties. first, the mean - tide system is adopted for handling the permanent tide. second, the reference level of height system is defined by the equipotential surface where the geopotential has a conventional value w0 = 62636853. 4 m2s - 2. this value was first determined empirically to provide a good approximation to the global mean sea level and then adopted as a reference value by convention. i analyse the tidal aspects of the reference level based on w0. the w0 is by definition independent of the tidal system adopted for the equipotential surface, but for different tidal systems, different functions are involved in the w of the equation w = w0. i find that the empirical determination of the adopted estimate w0 is inconsistent from the viewpoint of tidal systems. however, the adopted estimate and the consistent estimate from the same data round off to the same value. i propose a simplified definition of ihrf geopotential numbers that would make it possible to transform between ihrf and zero - tide geopotential numbers using a simple datum - difference surface. ihrf should adopt a conventional ( best ) estimate of the permanent tidal potential such as is contained in the iers conventions and use it as a basis for other conventional formulas. the tide - free coordinates of the itrf, and tide - free global geopotential models are central in the modelling of geopotential for the purposes of the ihrf. i present a set of correction formulas that can be used to move to the zero - tide model before, in the middle, or after the processing, and finally to the mean - tide ihrf. to reduce the confusion around the multitude of tidal systems i propose that modelling should primarily done in the zero - tide system, with the mean - tide potential as an add - on. | arxiv:2006.08440 |
helically spin - polarized dirac fermions ( hsdf ) in protected topological surface states ( tss ) are of high interest as a new state of quantum matter. in three - dimensional ( 3d ) materials with tss, electronic bulk states often mask the transport properties of hsdf. recently, the high - field hall resistance and low - field magnetoresistance indicate that the tss may coexist with a layered two - dimensional electronic system ( 2des ). here, we demonstrate quantum oscillations of the hall resistance at temperatures up to 50 k in bulk bi $ _ 2 $ se $ _ 3 $ with a high electron density $ n $ of about $ 2 \! \ cdot \! 10 ^ { 19 } $ cm $ ^ { - 3 } $. from the angular and temperature dependence of the hall resistance and the shubnikov - de haas oscillations we identify 3d and 2d contributions to transport. angular resolved photoemission spectroscopy proves the existence of tss. we present a model for bi $ _ 2 $ se $ _ 3 $ and suggest that the coexistence of tss and 2d layered transport stabilizes the quantum oscillations of the hall resistance. | arxiv:1707.09181 |
slip transfer at grain boundaries and annealing twin boundaries was studied in polycrystalline ni by means of slip trace analysis. slip transfer or blocking was assessed in $ > $ 200 boundaries and was related with geometrical criteria that establish the alignment between the active slip systems across the boundaries. it was found that slip transfer mainly occurs at low - angle regular grain boundaries and that a luster - morris parameter $ > $ 0. 8 stands for the best criterion to assess slip transfer. in the case of coherent or incoherent twin boundaries, slip transfer occurs when the residual burgers vector is close to zero through dislocation cross - slip. | arxiv:2201.04936 |
after a short summary of my talk, i discuss $ k _ { l3 } $ decays and elastic $ \ pi \ pi $ scattering in the framework of chiral perturbation theory. | arxiv:hep-ph/9906543 |
in this paper, we explore the potential of the lhc to measure the rate of $ \ mathrm { p } \ mathrm { p } \ rightarrow \ mathrm { p } ~ ww \ gamma ~ \ mathrm { p } $ process, also to probe the new effective couplings contributing to the $ ww \ gamma $ and $ ww \ gamma \ gamma $ vertices. the analysis is performed at the $ \ sqrt { s } = 13 $ tev, in the di - leptonic decay channel, and assuming 300 $ fb ^ { - 1 } $ integrated luminosity ( il ). in addition to the presence of two opposite sign leptons, a photon, and missing energy, the distinctive signature of this process is the presence of two intact protons flying few millimeters from the initial beam direction in both sides of interaction points which suppress the background process effectively. to exploit this feature of signal we benefit from forward detectors ( fds ) placed about 200 meters from the interaction point to register the kinematics of tagged protons. in order to overcome the major sources of backgrounds, we introduced three categories of selection cuts dealing with objects that strike the central detector, protons hitting the fds, and correlations of central objects and protons, respectively. we also evaluate the probability of pile - up protons to be tagged in the fds as a function of the mean number of pile - up. then the sensitivity of the lhc to observe this process and constraints on multi - boson effective couplings are extracted. the obtained expected limits show very good improvements for dimension - 8 quartic couplings and competitive bounds on dimension - 6 anomalous triple couplings w. r. t the current experimental limits. therefore, we propose this process to the lhc experiments as a sensitive and complementary channel to study the multi - gauge boson couplings. | arxiv:2004.12203 |
the existence of martingale solutions of the hydrodynamic - type equations in 3d possibly unbounded domains is proved. the construction of the solution is based on the faedo - galerkin approximation. to overcome the difficulty related to the lack of the compactness of sobolev embeddings in the case of unbounded domain we use certain fr \ ' { e } chet space. we use also compactness and tightness criteria in some nonmetrizable spaces and a version of the skorokhod theorem in non - metric spaces. the general framework is applied to the stochastic navier - stokes, magneto - hydrodynamic ( mhd ) and the boussinesq equations. | arxiv:1306.5342 |
the low - lying structure of $ ^ { 55 } $ sc has been investigated using in - beam $ \ gamma $ - ray spectroscopy with the $ ^ { 9 } $ be ( $ ^ { 56 } $ ti, $ ^ { 55 } $ sc + $ \ gamma $ ) $ x $ one - proton removal and $ ^ { 9 } $ be ( $ ^ { 55 } $ sc, $ ^ { 55 } $ sc + $ \ gamma $ ) $ x $ inelastic - scattering reactions at the riken radioactive isotope beam factory. transitions with energies of 572 ( 4 ), 695 ( 5 ), 1539 ( 10 ), 1730 ( 20 ), 1854 ( 27 ), 2091 ( 19 ), 2452 ( 26 ), and 3241 ( 39 ) kev are reported, and a level scheme has been constructed using $ \ gamma \ gamma $ coincidence relationships and $ \ gamma $ - ray relative intensities. the results are compared to large - scale shell - model calculations in the $ sd $ - $ pf $ model space, which account for positive - parity states from proton - hole cross - shell excitations, and to it ab initio shell - model calculations from the in - medium similarity renormalization group that includes three - nucleon forces explicitly. the results of proton - removal reaction theory with the eikonal model approach were adopted to aid identification of positive - parity states in the level scheme ; experimental counterparts of theoretical $ 1 / 2 ^ { + } _ { 1 } $ and $ 3 / 2 ^ { + } _ { 1 } $ states are suggested from measured decay patterns. the energy of the first $ 3 / 2 ^ { - } $ state, which is sensitive to the neutron shell gap at the fermi surface, was determined. the result indicates a rapid weakening of the $ n = 34 $ subshell closure in $ pf $ - shell nuclei at $ z > 20 $, even when only a single proton occupies the $ \ pi f _ { 7 / 2 } $ orbital. | arxiv:1710.07465 |
microboone is a neutrino experiment located in the booster neutrino beamline ( bnb ) at fermilab, which collected data from 2015 to 2021. microboone ' s liquid argon time projection chamber ( lartpc ) is accompanied by a photon detection system consisting of 32 photomultiplier tubes used to measure the argon scintillation light and determine the timing of neutrino interactions. analysis techniques combining light signals and reconstructed tracks are applied to achieve a neutrino interaction time resolution of $ \ mathcal { o } ( 1 \, \ text { ns } ) $. the result obtained allows microboone to access the ns neutrino pulse structure of the bnb for the first time. the timing resolution achieved will enable significant enhancement of cosmic background rejection for all neutrino analyses. furthermore, the ns timing resolution opens new avenues to search for long - lived - particles such as heavy neutral leptons in microboone, as well as in future large lartpc experiments, namely the sbn program and dune. | arxiv:2304.02076 |
the electromagnetic radiation that followed the neutron star merger event gw170817 revealed that gamma - ray burst afterglows from jets misaligned with our line of sight exhibit a light curve with slowly rising flux. the slope of the rising light curve depends sensitively on the angle of the observer with respect to the jet axis, which is likely to be perpendicular to the merger plane of the neutron star binary. therefore, the afterglow emission can be used to constrain the inclination of the merging system. here, we calculate the gamma - ray burst afterglow emission based on the realistic jet structure derived from general - relativistic magnetohydrodynamical simulations of a black hole torus system for the central engine of the gamma - ray burst. combined with gravitational wave parameter estimation, we fit the multi - epoch afterglow emission of gw170817. we show that with such a jet model, the observing angle can be tightly constrained by multi messenger observations. the best fit observing angle of gw170817 is $ \ theta _ { \ rm v } = 0. 38 \ pm 0. 02 $ rad. with such a constraint, we can break the degeneracy between inclination angle and luminosity distance in gravitational wave parameter estimation, and substantially increase the precision with which the hubble constant is constrained by the standard siren method. our estimation of the distance is $ d _ { \ rm l } = 43. 4 \ pm 1 \ \ rm mpc $ and the hubble constant constraint is $ 69. 5 \ pm 4 \ \ mathrm { km \ s ^ { - 1 } \ mpc ^ { - 1 } } $. as a result, multimessenger observations of short - duration gamma - ray bursts, combined with a good theoretical understanding of the jet structure, can be powerful probes of cosmological parameters. | arxiv:2009.04427 |
in this paper, we propose a new self - triggered consensus algorithm in networks of multi - agents. different from existing works, which are based on the observation of states, here, each agent determines its next update time based on its coupling structure. both centralized and distributed approaches of the algorithms have been discussed. by transforming the algorithm to a proper discrete - time systems without self delays, we established a new analysis framework to prove the convergence of the algorithm. then we extended the algorithm to networks with switching topologies, especially stochastically switching topologies. compared to existing works, our algorithm is easier to understand and implement. it explicitly provides positive lower and upper bounds for the update time interval of each agent based on its coupling structure, which can also be independently adjusted by each agent according to its own situation. our work reveals that the event / self triggered algorithms are essentially discrete and more suitable to a discrete analysis framework. numerical simulations are also provided to illustrate the theoretical results. | arxiv:1501.07349 |
the observations of magnetic field variations as a signature of flaring activity is one of the main goal in solar physics. some efforts in the past give apparently no unambiguous observations of changes. we observed that the scaling laws of the current helicity inside a given flaring active region change clearly and abruptly in correspondence with the eruption of big flares at the top of that active region. comparison with numerical simulations of mhd equations, indicates that the change of scaling behavior in the current helicity, seems to be associated to a topological reorganization of the footpoint of the magnetic field loop, namely to dissipation of small scales structures in turbulence. it is evident that the possibility of forecasting in real time high energy flares, even if partially, has a wide practical interest to prevent the effects of big flares on earth and its environment. | arxiv:astro-ph/0207244 |
a search for the direct production of charginos and neutralinos in final states with at least two hadronically decaying tau leptons is presented. the analysis uses a dataset of $ pp $ collisions corresponding to an integrated luminosity of 36. 1 fb $ ^ { - 1 } $, recorded with the atlas detector at the large hadron collider at a centre - of - mass energy of 13 tev. no significant deviation from the standard model background expectation is observed. limits are derived in scenarios of $ \ tilde { \ chi } _ { 1 } ^ { + } \ tilde { \ chi } _ { 1 } ^ { - } $ pair production and of $ \ tilde { \ chi } _ { 1 } ^ { \ pm } \ tilde { \ chi } _ { 2 } ^ { 0 } $ and $ \ tilde { \ chi } _ { 1 } ^ { + } \ tilde { \ chi } _ { 1 } ^ { - } $ production in simplified models where the neutralinos and charginos decay solely via intermediate left - handed staus and tau sneutrinos, and the mass of the $ \ tilde { \ tau } _ { \ mathrm l } $ state is set to be halfway between the masses of the $ \ tilde { \ chi } _ { 1 } ^ { \ pm } $ and the $ \ tilde { \ chi } _ { 1 } ^ { 0 } $. chargino masses up to 630 gev are excluded at 95 % confidence level in the scenario of direct production of $ \ tilde { \ chi } _ { 1 } ^ { + } \ tilde { \ chi } _ { 1 } ^ { - } $ for a massless $ \ tilde { \ chi } _ { 1 } ^ { 0 } $. common $ \ tilde { \ chi } _ { 1 } ^ { \ pm } $, $ \ tilde { \ chi } _ { 2 } ^ { 0 } $ masses up to 760 gev are excluded in the case of production of $ \ tilde { \ chi } _ { 1 } ^ { \ pm } \ tilde { \ chi } _ { 2 } ^ { 0 } $ and $ \ tilde { \ chi } _ { 1 } ^ { + } \ tilde { \ chi } _ { 1 } ^ { - } $ assuming a massless $ \ til | arxiv:1708.07875 |
in this short note, we propose a scheme, in which two instances of an equatorial state ( or a polar state ) can be remotely prepared in one - shot operation to different receivers with prior entanglement and 1 bit of broadcasting. the trade - off curve between the amount of entanglement and the achievable fidelity is derived. | arxiv:quant-ph/0302170 |
and another which is negative and denoted − x 0. { \ displaystyle - { \ sqrt { x _ { 0 } } }. } these choices define two continuous functions, both having the nonnegative real numbers as a domain, and having either the nonnegative or the nonpositive real numbers as images. when looking at the graphs of these functions, one can see that, together, they form a single smooth curve. it is therefore often useful to consider these two square root functions as a single function that has two values for positive x, one value for 0 and no value for negative x. in the preceding example, one choice, the positive square root, is more natural than the other. this is not the case in general. for example, let consider the implicit function that maps y to a root x of x 3 − 3 x − y = 0 { \ displaystyle x ^ { 3 } - 3x - y = 0 } ( see the figure on the right ). for y = 0 one may choose either 0, 3, or − 3 { \ displaystyle 0, { \ sqrt { 3 } }, { \ text { or } } - { \ sqrt { 3 } } } for x. by the implicit function theorem, each choice defines a function ; for the first one, the ( maximal ) domain is the interval [ −2, 2 ] and the image is [ −1, 1 ] ; for the second one, the domain is [ −2, ∞ ) and the image is [ 1, ∞ ) ; for the last one, the domain is ( −∞, 2 ] and the image is ( −∞, −1 ]. as the three graphs together form a smooth curve, and there is no reason for preferring one choice, these three functions are often considered as a single multi - valued function of y that has three values for −2 < y < 2, and only one value for y ≤ −2 and y ≥ −2. usefulness of the concept of multi - valued functions is clearer when considering complex functions, typically analytic functions. the domain to which a complex function may be extended by analytic continuation generally consists of almost the whole complex plane. however, when extending the domain through two different paths, one often gets different values. for example, when extending the domain of the square root function, along a path of complex numbers with positive imaginary parts, one gets i for the square root of −1 ; while, when extending through complex numbers with negative | https://en.wikipedia.org/wiki/Function_(mathematics) |
the gribov - zwanziger prescription applied within yang - mills theory is demonstrated to be an efficient method for refining the theory ' s infrared dynamics. we study the collisional energy loss experienced by a high - energetic test parton as it traverses through the grivov plasma at finite temperature. to achieve this, we employ a semi - classical approach that considers the parton ' s energy loss while accounting for the back - reaction induced by the polarization effects due to its motion in the medium. the polarization tensor of the medium is estimated within a non - perturbative resummation considering the gribov - zwanziger approach. the modification of the gluon and ghost loops due to the presence of the gribov parameter plays a vital role in our estimation. we observe that the non - perturbative interactions have a sizable effect on the parton energy loss. further, we discuss the implications of our findings in the context of relativistic heavy - ion collisions. | arxiv:2311.16005 |
this article explores citing and referencing systems in social sciences and medicine articles from different theoretical and practical perspectives, considering bibliographic references as a facet of descriptive representation. the analysis of citing and referencing elements ( i. e. bibliographic references, mentions, quotations, and respective in - text reference pointers ) identified citing and referencing habits within disciplines under consideration and errors occurring over the long term as stated by previous studies now expanded. future expected trends of information retrieval from bibliographic metadata was gathered by approaching these referencing elements from the frbr entities concepts. reference styles do not fully accomplish with their role of guiding authors and publishers on providing concise and well - structured bibliographic metadata within bibliographic references. trends on representative description revision suggest a predicted distancing on the ways information is approached by bibliographic references and bibliographic catalogs adopting frbr concepts, including the description levels adopted by each of them under the perspective of the frbr entities concept. this study was based on a subset of medicine and social sciences articles published in 2019 and, therefore, it may not be taken as a final and broad coverage. future studies expanding these approaches to other disciplines and chronological periods are encouraged. by approaching citing and referencing issues as descriptive representation ' s facets, findings on this study may encourage further studies that will support information science and computer science on providing tools to become bibliographic metadata description simpler, better structured and more efficient facing the revision of descriptive representation actually in progress. | arxiv:2009.05588 |
the analysis can improve the constraints on $ r $ and $ n _ s $. we further discuss the implications of our constraints on the test of inflation models. | arxiv:1207.6113 |
we consider jacobi matrices with eventually increasing sequences of diagonal and off - diagonal jacobi parameters. we describe the asymptotic behavior of the subordinate solution at the top of the essential spectrum, and the asymptotic behavior of the spectral density at the top of the essential spectrum. in particular, allowing on both diagonal and off - diagonal jacobi parameters perturbations of the free case of the form $ - \ sum _ { j = 1 } ^ j c _ j n ^ { - \ tau _ j } + o ( n ^ { - \ tau _ 1 - 1 } ) $ with $ 0 < \ tau _ 1 < \ tau _ 2 < \ dots < \ tau _ j $ and $ c _ 1 > 0 $, we find the asymptotic behavior of the $ \ log $ of spectral density to order $ o ( \ log ( 2 - x ) ) $ as $ x $ approaches $ 2 $. apart from its intrinsic interest, the above results also allow us to describe the asymptotics of the spectral density for orthogonal polynomials on the unit circle with real - valued verblunsky coefficients of the same form. | arxiv:1705.09461 |
we consider convex sgd updates with a block - cyclic structure, i. e. where each cycle consists of a small number of blocks, each with many samples from a possibly different, block - specific, distribution. this situation arises, e. g., in federated learning where the mobile devices available for updates at different times during the day have different characteristics. we show that such block - cyclic structure can significantly deteriorate the performance of sgd, but propose a simple approach that allows prediction with the same performance guarantees as for i. i. d., non - cyclic, sampling. | arxiv:1904.10120 |
we show in this paper that the correspondence between $ 2 $ - term representations up to homotopy and $ \ mathcal { vb } $ - algebroids, established by gracia - saz and mehta, holds also at the level of morphisms. this correspondence is hence an equivalence of categories. as an application, we study foliations and distributions on a lie algebroid, that are compatible both with the linear structure and the lie algebroid structure. in particular, we show how infinitesimal ideal systems in a lie algebroid $ a $ are related with subrepresentations of the adjoint representation of $ a $. | arxiv:1302.3987 |
determining the nature - dirac or majorana - of massive neutrinos is one of the most pressing and challenging problems in the field of neutrino physics. we discuss how one can possibly extract information on the couplings, if any, which might be involved in neutrinoless double beta - decay using a multi - isotope approach. we investigate as well the potential of combining data on the half - lives of nuclides which largely different nuclear matrix elements such as $ ^ { 136 } $ xe and of one or more of the four nuclei $ ^ { 76 } $ ge, $ ^ { 82 } $ se, $ ^ { 100 } $ mo and $ ^ { 130 } $ te, for discriminating between different pairs of non - interfering or interfering mechanisms of neutrinoless double beta - decay. the case studies do not extend to the evaluation of the theoretical uncertainties of the results, due to the nuclear matrix elements calculations and other causes. | arxiv:1510.05523 |
while the body of research directed towards constructing and generating clarifying questions in mixed - initiative conversational search systems is vast, research aimed at processing and comprehending users ' answers to such questions is scarce. to this end, we present a simple yet effective method for processing answers to clarifying questions, moving away from previous work that simply appends answers to the original query and thus potentially degrades retrieval performance. specifically, we propose a classifier for assessing usefulness of the prompted clarifying question and an answer given by the user. useful questions or answers are further appended to the conversation history and passed to a transformer - based query rewriting module. results demonstrate significant improvements over strong non - mixed - initiative baselines. furthermore, the proposed approach mitigates the performance drops when non useful questions and answers are utilized. | arxiv:2401.11463 |
we give the formula for the maximal systole of the surface admits the largest $ s ^ 3 $ - extendable abelian group symmetry. the result we get is $ 2 \ mathrm { arccosh } k $. here \ begin { eqnarray * } k & = & \ sqrt [ 3 ] { \ frac { 1 } { 216 } l ^ 3 + \ frac { 1 } { 8 } l ^ 2 + \ frac { 5 } { 8 } l - \ frac { 1 } { 8 } + \ sqrt { \ frac { 1 } { 108 } l ( l ^ 2 + 18l + 27 ) } } & & + \ sqrt [ 3 ] { \ frac { 1 } { 216 } l ^ 3 + \ frac { 1 } { 8 } l ^ 2 + \ frac { 5 } { 8 } l - \ frac { 1 } { 8 } - \ sqrt { \ frac { 1 } { 108 } l ( l ^ 2 + 18l + 27 ) } } & & + \ frac { l + 3 } { 6 }. \ end { eqnarray * } and $ l = 4 \ cos ^ 2 \ frac { \ pi } { g - 1 } $. | arxiv:1911.10474 |
in doped manganites, the strong electron - phonon coupling due to the jahn - teller effect localizes the conduction - band electrons as polarons. this results in polarons are carriers responsible for transport and ferromagnetic ordering rather than the bare eg electrons, and sequentially polaron exchange model is emerged for describing ferromagnetic ordering. in pr0. 7 ( sr1 - xcax ) 0. 3mno3 ( x = 0. 3 - 0. 6 ) epitaxial thin films, for higher - temperature paramagnetic state and lower - temperature ferromagnetic state, both the temperature dependent transports present behaviors of small polaron ; for paramagnetic - ferromagnetic transition, the experimental data of curie temperature are well described by an energy balance expression induced by polaron exchange model. these results demonstrate that the polaron models are proper ways to describe the strongly correlated electrons in the doped manganites. | arxiv:0812.2722 |
the capability of cosmic inflation to explain the latest cosmic microwave background and baryonic acoustic oscillation data is assessed by performing bayesian model comparison within the landscape of nearly three - hundred models of single - field slow - roll inflation. we present the first bayesian data analysis based on the third - order slow - roll primordial power spectra. in particular, the fourth hubble - flow function $ \ epsilon _ 4 $ remains unbounded while the third function verifies, at two - sigma, $ \ epsilon _ { 3 } \ in [ - 0. 4, 0. 5 ] $, which is perfectly compatible with the slow - roll predictions for the running of the spectral index. we also observe some residual excess of $ b $ - modes within the bicep / keck data favoring, at a non - statistically significant level, non - vanishing primordial tensor modes : $ \ log ( \ epsilon _ { 1 } ) > - 3. 9 $, at $ 68 \ % $ confidence level. then, for 283 models of single - field inflation, we compute the bayesian evidence, the bayesian dimensionality and the marginalized posteriors of all the models ' parameters, including the ones associated with the reheating era. the average information gain on the reheating parameter $ r _ \ mathrm { reh } $ reaches $ 1. 3 \ pm 0. 18 $ bits, which is more than a factor two improvement compared to the first planck data release. as such, inflationary model predictions cannot meet data accuracy without specifying, or marginalizing over, the reheating kinematics. we also find that more than $ 40 \ % $ of the scenarios are now strongly disfavored, which shows that the constraining power of cosmological data is winning against the increase of the number of proposed models. in addition, about $ 20 \ % $ of all models have evidences within the most probable region and are all favored according to the jeffreys ' scale of bayesian evidences. | arxiv:2404.10647 |
this paper develops a bayesian control chart for the percentiles of the weibull distribution, when both its in - control and out - of - control parameters are unknown. the bayesian approach enhances parameter estimates for small sample sizes that occur when monitoring rare events as in high - reliability applications or genetic mutations. the chart monitors the parameters of the weibull distribution directly, instead of transforming the data as most weibull - based charts do in order to comply with their normality assumption. the chart uses the whole accumulated knowledge resulting from the likelihood of the current sample combined with the information given by both the initial prior knowledge and all the past samples. the chart is adapting since its control limits change ( e. g. narrow ) during the phase i. an example is presented and good average run length properties are demonstrated. in addition, the paper gives insights into the nature of monitoring weibull processes by highlighting the relationship between distribution and process parameters. | arxiv:1308.0691 |
a plethora of recent work has shown that convolutional networks are not robust to adversarial images : images that are created by perturbing a sample from the data distribution as to maximize the loss on the perturbed example. in this work, we hypothesize that adversarial perturbations move the image away from the image manifold in the sense that there exists no physical process that could have produced the adversarial image. this hypothesis suggests that a successful defense mechanism against adversarial images should aim to project the images back onto the image manifold. we study such defense mechanisms, which approximate the projection onto the unknown image manifold by a nearest - neighbor search against a web - scale image database containing tens of billions of images. empirical evaluations of this defense strategy on imagenet suggest that it is very effective in attack settings in which the adversary does not have access to the image database. we also propose two novel attack methods to break nearest - neighbor defenses, and demonstrate conditions under which nearest - neighbor defense fails. we perform a series of ablation experiments, which suggest that there is a trade - off between robustness and accuracy in our defenses, that a large image database ( with hundreds of millions of images ) is crucial to get good performance, and that careful construction the image database is important to be robust against attacks tailored to circumvent our defenses. | arxiv:1903.01612 |
deep learning models often raise privacy concerns as they leak information about their training data. this enables an adversary to determine whether a data point was in a model ' s training set by conducting a membership inference attack ( mia ). prior work has conjectured that regularization techniques, which combat overfitting, may also mitigate the leakage. while many regularization mechanisms exist, their effectiveness against mias has not been studied systematically, and the resulting privacy properties are not well understood. we explore the lower bound for information leakage that practical attacks can achieve. first, we evaluate the effectiveness of 8 mechanisms in mitigating two recent mias, on three standard image classification tasks. we find that certain mechanisms, such as label smoothing, may inadvertently help mias. second, we investigate the potential of improving the resilience to mias by combining complementary mechanisms. finally, we quantify the opportunity of future mias to compromise privacy by designing a white - box ` distance - to - confident ' ( dtc ) metric, based on adversarial sample crafting. our metric reveals that, even when existing mias fail, the training samples may remain distinguishable from test samples. this suggests that regularization mechanisms can provide a false sense of privacy, even when they appear effective against existing mias. | arxiv:2006.05336 |
errors and inefficiencies. among the finding of meta - research is a low rates of reproducibility across a large number of fields. = = = replication crisis = = = = = = academic bias = = = = = = funding bias = = = = = = publication bias = = = = = = non - western methods = = = in many disciplines, western methods of conducting research are predominant. researchers are overwhelmingly taught western methods of data collection and study. the increasing participation of indigenous peoples as researchers has brought increased attention to the scientific lacuna in culturally sensitive methods of data collection. western methods of data collection may not be the most accurate or relevant for research on non - western societies. for example, " hua oranga " was created as a criterion for psychological evaluation in maori populations, and is based on dimensions of mental health important to the maori people – " taha wairua ( the spiritual dimension ), taha hinengaro ( the mental dimension ), taha tinana ( the physical dimension ), and taha whanau ( the family dimension ) ". even though western dominance seems to be prominent in research, some scholars, such as simon marginson, argue for " the need [ for ] a plural university world ". marginson argues that the east asian confucian model could take over the western model. this could be due to changes in funding for research both in the east and the west. focused on emphasizing educational achievement, east asian cultures, mainly in china and south korea, have encouraged the increase of funding for research expansion. in contrast, in the western academic world, notably in the united kingdom as well as in some state governments in the united states, funding cuts for university research have occurred, which some say may lead to the future decline of western dominance in research. = = = language = = = research is often biased in the languages that are preferred ( linguicism ) and the geographic locations where research occurs. periphery scholars face the challenges of exclusion and linguicism in research and academic publication. as the great majority of mainstream academic journals are written in english, multilingual periphery scholars often must translate their work to be accepted to elite western - dominated journals. multilingual scholars ' influences from their native communicative styles can be assumed to be incompetence instead of difference. patterns of geographic bias also show a relationship with linguicism : countries whose official languages are french or arabic are far less likely to be the focus of single - country | https://en.wikipedia.org/wiki/Research |
for the spatial generalized $ n $ - centre problem $ $ \ ddot { x } = - \ sum _ { i = 1 } ^ { n } \ frac { m _ i ( x - c _ i ) } { \ vert x - c _ i \ vert ^ { \ alpha + 2 } }, \ qquad x \ in \ mathbb { r } ^ 3 \ setminus \ { c _ 1, \ dots, c _ n \ }, $ $ where $ m _ i > 0 $ and $ \ alpha \ in [ 1, 2 ) $, we prove the existence of positive energy entire solutions with prescribed scattering angle. the proof relies on variational arguments, within an approximation procedure via ( free - time ) boundary value problems. a self - contained appendix describing a general strategy to rule out the occurrence of collisions is also included. | arxiv:1710.00522 |
we study particle and chirality production from the vacuum in the presence of a slow strong parallel electromagnetic field superimposed by a fast weak perturbative electromagnetic field. we derive an analytical formula for the particle and chirality production number based on the perturbation theory in the furry picture. with the formula, we analytically discuss the interplay and dynamical assistance between the schwinger mechanism and one - photon pair production and clarify effects of a parallel slow strong magnetic field. we also show that the dynamical assistance can significantly enhance chirality production, and that a sizable amount of chirality can be produced even for massive particles. phenomenological applications including heavy - ion collisions and intense laser experiments are also discussed. | arxiv:2003.08948 |
non - relativistic interacting bosons at zero temperature, in two and three dimensions, are expected to exhibit a fascinating critical phase, famously known as condensate phase. even though a proof of bose - einstein condensation in the thermodynamic limit is still beyond reach of the current available methods, in the past decades the mathematical physics community has gained an enhanced comprehension of other aspects of the macroscopic behavior of dilute bose gases at zero temperature. in these notes we review part of these advances, by focusing on the strict relation among the occurrence of bose - einstein condensation on large - - but finite - - boxes, and the asymptotic expansion to the ground state energy of dilute bose gases. | arxiv:2209.11714 |
we present a combined experimental and theoretical study on copper pyrimidine dinitrate [ cupm ( no3 ) 2 ( h2o ) 2 ] n, a one - dimensional s = 1 / 2 antiferromagnet with alternating local symmetry. from the local susceptibility measured by nmr at the three inequivalent carbon sites in the pyrimidine molecule we deduce a giant spin canting, i. e., an additional staggered magnetization perpendicular to the applied external field at low temperatures. the magnitude of the transverse magnetization, the spin canting of 52 degrees at 10 k and 9. 3 t and its temperature dependence are in excellent agreement with exact diagonalization calculations. | arxiv:cond-mat/0405147 |
light top superpartners play a key role in stabilizing the electroweak scale in supersymmetric theories. for $ r $ - parity conserved supersymmetric models, traditional searches are not sensitive to the compressed regions. in this paper, we propose a new method targeting this region, with stop and neutralino mass splitting ranging from $ m _ { \ tilde t } - m _ \ chi \ gtrsim m _ t $ to about 20 gev. in particular, we focus on the signal process in which a pair of stops are produced in association with a hard jet, and define a new observable $ r _ m $ whose distribution has a peak in this compressed region. the position of the peak is closely correlated with $ m _ { \ tilde t } $. we show that for 13 tev lhc with a luminosity of 3000 fb $ ^ { - 1 } $, this analysis can extend the reach of stop in the compressed region to $ m _ { \ tilde t } $ around 800 gev. | arxiv:1506.00653 |
density estimation trees ( dets ) are decision trees trained on a multivariate dataset to estimate its probability density function. while not competitive with kernel techniques in terms of accuracy, they are incredibly fast, embarrassingly parallel and relatively small when stored to disk. these properties make dets appealing in the resource - expensive horizon of the lhc data analysis. possible applications may include selection optimization, fast simulation and fast detector calibration. in this contribution i describe the algorithm, made available to the hep community in a roofit implementation. a set of applications under discussion within the lhcb collaboration are also briefly illustrated. | arxiv:1607.06635 |
we propose techniques for optimizing transmit beamforming in a full - duplex multiple - input - multiple - output ( mimo ) wireless - powered communication system, which consists of two phases. in the first phase, the wireless - powered mobile station ( ms ) harvests energy using signals from the base station ( bs ), whereas in the second phase, both ms and bs communicate to each other in a full - duplex mode. when complete instantaneous channel state information ( csi ) is available, the bs beamformer and the time - splitting ( ts ) parameter of energy harvesting are jointly optimized in order to obtain the bs - ms rate region. the joint optimization problem is non - convex, however, a computationally efficient optimum technique, based upon semidefinite relaxation and line - search, is proposed to solve the problem. a sub - optimum zero - forcing approach is also proposed, in which a closed - form solution of ts parameter is obtained. when only second - order statistics of transmit csi is available, we propose to maximize the ergodic information rate at the ms, while maintaining the outage probability at the bs below a certain threshold. an upper bound for the outage probability is also derived and an approximate convex optimization framework is proposed for efficiently solving the underlying non - convex problem. simulations demonstrate the advantages of the proposed methods over the sub - optimum and half - duplex ones. | arxiv:1705.04014 |
let $ ( m, g ) $ be a closed riemannian manifold, where g is $ c ^ 1 $ - smooth metric. consider the sequence of eigenfunctions $ u _ k $ of the laplace operator on m. let $ b $ be a ball on $ m $. we prove a sharp estimate of the number of nodal domains of $ u _ k $ that intersect $ b $. the problem of local bounds for the volume and for the number of nodal domains was raised by donnelly and fefferman, who also proposed an idea how one can prove such bounds. we combine their idea with two ingredients : the recent sharp remez type inequality for eigenfunctions and the landis type growth lemma in narrow domains. | arxiv:2008.00677 |
conjure is an automated modelling tool for constraint programming. in this documentation, you will find the following : a brief introduction to conjure, installation instructions, a description of how to use conjure through its command line user interface, a list of conjure ' s features, a description of conjure ' s input language essence, and a collection of simple demonstrations of conjure ' s use. | arxiv:1910.00475 |
we discuss gauge theories on d3 branes embedded in special non - tachyonic orientifolds of the 0b string theory. in general, they correspond to non - supersymmetric su ( n ) gauge theories with scalars in the adjoint representation and spinors in the ( anti - ) symmetric representation. we study these theories via the ads / cft correspondence and present evidence of their relation to n = 4 sym in the planar limit. we also discuss finite n properties, focusing in particular on the renormalization group flow. up to two loops, the logarithmic running of the gauge coupling is described by the dilaton tadpole and the cosmological constant that naturally emerge on the string theory side. | arxiv:hep-th/9912257 |
let g be a lie group over a local field of positive characteristic which admits a contractive automorphism f ( i. e., the forward iterates f ^ n ( x ) of each group element x converge to the neutral element 1 ). we show that then g is a torsion group of finite exponent and nilpotent. we also obtain results concerning the interplay between contractive automorphisms of lie groups over local fields, contractive automorphisms of their lie algebras, and positive gradations thereon. some of the results even extend to lie groups over arbitrary complete ultrametric fields. | arxiv:0704.3737 |
triply periodic minimal surfaces ( tpms ) possess locally minimized surface area under the constraint of periodic boundary conditions. different families of surfaces were obtained with different topologies satisfying such conditions. examples of such families include primitive ( p ), gyroid ( g ) and diamond ( d ) surfaces. from a purely mathematical subject, tpms have been recently found in materials science as optimal geometries for structural applications. proposed by mackay and terrones in 1991, schwarzites are 3d crystalline porous carbon nanocrystals exhibiting the shape of tpms. although their complex topology poses serious limitations on their synthesis with conventional nanoscale fabrication methods, such as chemical vapour deposition ( cvd ), tpms can be fabricated by additive manufacturing ( am ) techniques, such as 3d printing. in this work, we used an optimized atomic model of a schwarzite structure from the d family ( d8bal ) to generate a surface mesh that was subsequently used for 3d - printing through fused deposition modelling ( fdm ). this d schwarzite was 3d - printed with thermoplastic polylactic acid ( pla ) polymer filaments. mechanical properties under uniaxial compression were investigated for both the atomic model and the 3d - printed one. fully atomistic molecular dynamics ( md ) simulations were also carried out to investigate the uniaxial compression behavior of the d8bal atomic model. mechanical testings were performed on the 3d - printed schwarzite where the deformation mechanisms were found to be similar to those observed in md simulations. these results are suggestive of a scale - independent mechanical behavior that is dominated by structural topology. | arxiv:2001.03430 |
in the disjoint paths problem, one is given a graph with a set of $ k $ vertex pairs $ ( s _ i, t _ i ) $ and the task is to connect each $ s _ i $ to $ t _ i $ with a path, so that the $ k $ paths are pairwise disjoint. in the optimization variant, max disjoint paths, the goal is to maximize the number of vertex pairs to be connected. we study this problem on acyclic directed graphs, where disjoint paths is known to be w [ 1 ] - hard when parameterized by $ k $. we show that in this setting max disjoint paths is w [ 1 ] - hard to $ c $ - approximate for any constant $ c $. to the best of our knowledge, this is the first non - trivial result regarding the parameterized approximation for max disjoint paths with respect to the natural parameter $ k $. our proof is based on an elementary self - reduction that is guided by a certain combinatorial object constructed by the probabilistic method. | arxiv:2409.03596 |
we prove that the spectrum of the kirchhoff laplacian h0 of a finite simple barycentric refined graph and the spectrum of the connection laplacian l of g determine each other : we prove that l - l ^ ( - 1 ) is similar to the hodge laplacian h of g which is in one dimensions the direct sum of the kirchhoff laplacian h0 and its 1 - form analog h1. the spectrum of a single choice of h0, h1 or h alone determines the betti numbers b0, b1 of g as well as the spectrum of the other matrices. it follows that b0 is the number of eigenvalues 1 of l and that b1 is the number of eigenvalues - 1 of l. for a general abstract finite simplicial complex g, we express the matrix entries g ( x, y ) = w ( x ) w ( y ) x ( st ( x ) cap st ( y ) ) of the inverse of l using stars st ( x ) = { z in g | x subset of z } of x and w ( x ) = ( - 1 ) ^ dim ( x ) and euler characteristic x. one can see w + ( x ) = st ( x ) and w - ( x ) = { z in g | z subset x } as stable and unstable manifolds of a simplex x in g and g ( x, y ) = w ( x ) w ( y ) x ( w + ( x ) cap w + ( y ) ) as heteroclinic intersection numbers or curvatures and the identity l g = 1 as a collection of gauss - bonnet formulas. the homoclinic energy w ( x ) = x ( w + ( x ) cap w - ( x ) ) by definition adds up to x ( g ). the matrix m ( x, y ) = w ( x ) w ( y ) x ( w - ( x ) cap w - ( y ) ) is similar to l ( x, y ) = x ( w - ( x ) cap w - ( y ) ). the sum of the matrix entries of m is the definition of wu characteristic. for dimension 2 and higher we don ' t know yet how to recover the betti numbers from the eigenvalues of the matrix h or from l. so far, it can only be obtained from a collection of block matrices, via the hodge relations b _ k = dim ( h _ | arxiv:1802.01238 |
a recent submillimeter line survey of orion kl claimed detection of sih. this paper reports on gbt observations of the 5. 7 ghz lambda - doubling transitions of sih in orion. many recombination lines, including c164 - delta, are seen, but sih is not detected. the nondetection corresponds to an upper limit of 1. 5 x 10 ^ 15 cm ^ - 2 ( 4 sigma ) for the beam - averaged column density of sih. this suggests that the fractional abundance of sih in the extended ridge is no more than twice that in the hot core. | arxiv:astro-ph/0606495 |
we present new photometric observations of eclipsing binary systems v1241 tau and gq dra. we use the following methodology : initially, wd code is applied to the light curves, in order to determine the photometric elements of the systems. then the residuals are analysed using fourier transformation techniques. the results show that one frequency can be barely attributed to the residual light variation of v1241 tau, while there is no evidence of pulsation on the light curve of gq dra. | arxiv:1309.3130 |
the sampling kaczmarz - motzkin ( skm ) method is a generalization of the randomized kaczmarz and motzkin methods. it first samples some rows of coefficient matrix randomly to build a set and then makes use of the maximum violation criterion within this set to determine a constraint. finally, it makes progress by enforcing this single constraint. in this paper, on the basis of the framework of the skm method and considering the greedy strategies, we present two block sampling kaczmarz - motzkin methods for consistent linear systems. specifically, we also first sample a subset of rows of coefficient matrix and then determine an index in this set using the maximum violation criterion. unlike the skm method, in the rest of the block methods, we devise different greedy strategies to build index sets. then, the new methods make progress by enforcing the corresponding multiple constraints simultaneously. theoretical analyses demonstrate that these block methods converge at least as quickly as the skm method, and numerical experiments show that, for the same accuracy, our methods outperform the skm method in terms of the number of iterations and computing time. | arxiv:2011.06688 |
we investigate the statistical properties of eigenvalues of pseudo - hermitian random matrices whose eigenvalues are real or complex conjugate. it is shown that when the spectrum splits into separated sets of real and complex conjugate eigenvalues, the real ones show characteristics of an intermediate incomplete spectrum, that is, of a so - called thinned ensemble. on the other hand, the complex ones show repulsion compatible with cubic - order repulsion of non normal matrices for the real matrices, but higher order repulsion for the complex and quaternion matrices. | arxiv:2008.12088 |
multiprocessor task scheduling is an important and computationally difficult problem. this paper proposes a comparison study of genetic algorithm and list scheduling algorithm. both algorithms are naturally parallelizable but have heavy data dependencies. based on experimental results, this paper presents a detailed analysis of the scalability, advantages and disadvantages of each algorithm. multiprocessors have emerged as a powerful computing means for running real - time applications, especially where a uni - processor system would not be sufficient enough to execute all the tasks. the high performance and reliability of multiprocessors have made them a powerful computing resource. such computing environment requires an efficient algorithm to determine when and on which processor a given task should execute. in multiprocessor systems, an efficient scheduling of a parallel program onto the processors that minimizes the entire execution time is vital for achieving a high performance. this scheduling problem is known to be np - hard. in multiprocessor scheduling problem, a given program is to be scheduled in a given multiprocessor system such that the program ' s execution time is minimized. the last job must be completed as early as possible. genetic algorithm ( ga ) is one of the widely used techniques for constrained optimization. | arxiv:1002.1149 |
we present a new formula for all single trace tree amplitudes in four dimensional super yang - mills coupled to einstein supergravity. like the cachazo - he - yuan formula, our expression is supported on solutions of the scattering equations, but with momenta written in terms of spinor helicity variables. supersymmetry and parity are both manifest. in the pure gravity and pure yang - mills sectors, it reduces to the known twistor - string formulae. we show that the formula behaves correctly under factorization and sketch how these amplitudes may be obtained from a four - dimensional ( ambi ) twistor string. | arxiv:1507.02207 |
here we propose an analytically tractable model of an entangled quantum state subject to random shocks and prove that disentanglement occurs asymptotically. the system consists of two identical, two level state systems, say two entangled qubits or two entangled two state molecules, and the heat bath consists of the occurrence of state switching shocks, which happen at a poisson rate. the time dependence of such system can be explicitly obtained and the decay rate to disentanglement happens to be twice the frequency of the occurrence of shocks. | arxiv:2502.20096 |
deep neural networks have demonstrated impressive success in no - reference image quality assessment ( nr - iqa ). however, recent researches highlight the vulnerability of nr - iqa models to subtle adversarial perturbations, leading to inconsistencies between model predictions and subjective ratings. current adversarial attacks, however, focus on perturbing predicted scores of individual images, neglecting the crucial aspect of inter - score correlation relationships within an entire image set. meanwhile, it is important to note that the correlation, like ranking correlation, plays a significant role in nr - iqa tasks. to comprehensively explore the robustness of nr - iqa models, we introduce a new framework of correlation - error - based attacks that perturb both the correlation within an image set and score changes on individual images. our research primarily focuses on ranking - related correlation metrics like spearman ' s rank - order correlation coefficient ( srocc ) and prediction error - related metrics like mean squared error ( mse ). as an instantiation, we propose a practical two - stage srocc - mse - attack ( sma ) that initially optimizes target attack scores for the entire image set and then generates adversarial examples guided by these scores. experimental results demonstrate that our sma method not only significantly disrupts the srocc to negative values but also maintains a considerable change in the scores of individual images. meanwhile, it exhibits state - of - the - art performance across metrics with different categories. our method provides a new perspective on the robustness of nr - iqa models. | arxiv:2404.13277 |
we study algorithms for spectral graph sparsification. the input is a graph $ g $ with $ n $ vertices and $ m $ edges, and the output is a sparse graph $ \ tilde { g } $ that approximates $ g $ in an algebraic sense. concretely, for all vectors $ x $ and any $ \ epsilon > 0 $, $ \ tilde { g } $ satisfies $ $ ( 1 - \ epsilon ) x ^ t l _ g x \ leq x ^ t l _ { \ tilde { g } } x \ leq ( 1 + \ epsilon ) x ^ t l _ g x, $ $ where $ l _ g $ and $ l _ { \ tilde { g } } $ are the laplacians of $ g $ and $ \ tilde { g } $ respectively. we show that the fastest known algorithm for computing a sparsifier with $ o ( n \ log n / \ epsilon ^ 2 ) $ edges can actually run in $ \ tilde { o } ( m \ log ^ 2 n ) $ time, an $ o ( \ log n ) $ factor faster than before. we also present faster sparsification algorithms for slightly dense graphs. specifically, we give an algorithm that runs in $ \ tilde { o } ( m \ log n ) $ time and generates a sparsifier with $ \ tilde { o } ( n \ log ^ 3 { n } / \ epsilon ^ 2 ) $ edges. this implies that a sparsifier with $ o ( n \ log n / \ epsilon ^ 2 ) $ edges can be computed in $ \ tilde { o } ( m \ log n ) $ time for graphs with more than $ o ( n \ log ^ 4 n ) $ edges. we also give an $ \ tilde { o } ( m ) $ time algorithm for graphs with more than $ n \ log ^ 5 n ( \ log \ log n ) ^ 3 $ edges of polynomially bounded weights, and an $ o ( m ) $ algorithm for unweighted graphs with more than $ n \ log ^ 8 n ( \ log \ log n ) ^ 3 $ edges and $ n \ log ^ { 10 } n ( \ log \ log n ) ^ 5 $ edges in the weighted case. the improved sparsification algorithms are employed to accelerate linear system solvers and algorithms for computing fundamental eigenvectors of slightly dense sdd matrices. | arxiv:1209.5821 |
a value of ( - 6. 1 + - 0. 9 _ { stat } + - 0. 5 _ { syst } ) * 10 ^ { - 3 } is obtained for the quadratic slope parameter h in the k _ l - > 3 \ pi ^ 0 decay dalitz plot at the na48 experiment at the cern sps. the result is based on 14. 7 * 10 ^ 6 fully reconstructed k _ l - > 3 \ pi ^ 0 - > 6 \ gamma decays. this is the most precise measurement of any of the dalitz plot slope parameters in the charged and neutral kaon decays so far. | arxiv:hep-ex/0106075 |
we use photometric and spectroscopic observations of the eclipsing binaries v65, v66 and v69 in the field of the globular cluster m4 to derive masses, radii, and luminosities of their components. the orbital periods of these systems are 2. 29, 8. 11 and 48. 19 d, respectively. the measured masses of the primary and secondary components ( mp and ms ) are 0. 8035 + - 0. 0086 and 0. 6050 + - 0. 0044 msun for v65, 0. 7842 + - 0. 0045 and 0. 7443 + - 0. 0042 msun for v66, and 0. 7665 + - 0. 0053 and 0. 7278 + - 0. 0048 msun for v69. the measured radii ( rp and rs ) are 1. 147 + _ 0. 010 and 0. 6110 + - 0. 0092 rsun for v66, 0. 9347 + _ 0. 0048 and 0. 8298 + - 0. 0053 rsun for v66, and 0. 8655 + - 0. 0097 and 0. 8074 + - 0. 0080 rsun for v69. the orbits of v65 and v66 are circular, whereas that of v69 has an eccentricity of 0. 38. based on systemic velocities and relative proper motions, we show that all the three systems are members of the cluster. we find that the distance to m4 is 1. 82 + - 0. 04 kpc - in good agreement with recent estimates based on entirely different methods. we compare the absolute parameters of v66 and v69 with two sets of theoretical isochrones in mass - radius and mass - luminosity diagrams, and for an assumed [ fe / h ] = - 1. 20, [ alpha / fe ] = 0. 4, and y = 0. 25 we find the most probable age of m4 to be between 11. 2 and 11. 3 gyr. cmd - fitting with the same parameters yields an age close to, or slightly in excess of, 12 gyr. however, considering the sources of uncertainty involved in cmd fitting, these two methods of age determination are not discrepant. age and distance determinations can be further improved when infrared eclipse photometry is obtained. | arxiv:1301.2946 |
the final astrometric data from the gaia mission will transform our view of the stellar content of the galaxy, particularly when complemented with spectroscopic surveys providing stellar parameters, line - of - sight kinematics and elemental abundances. analyses with gaia dr1 are already demonstrating the insight gained and the promise of what is to come with future gaia releases. i present a brief overview of results and puzzles from recent galactic archaeology surveys for context, focusing on the galactic discs. | arxiv:1711.01517 |
we demonstrate quantum resonance ratchets created with bose - einstein condensates exposed to pulses of an off - resonant standing light wave. we show how some of the basic properties of the ratchets are controllable through the creation of different initial states of the system. in particular, our results prove that through an appropriate choice of initial state it is possible to reduce the extent to which the ratchet state changes with respect to time. we develop a simple theory to explain our results and indicate how ratchets might be used as part of a matter wave interferometer or quantum - random walk experiment. | arxiv:1608.09003 |
the search for weakly - interacting massive particle ( wimp ) dark matter is multi - pronged. ultimately, the wimp - dark - matter picture will only be confirmed if different classes of experiments see consistent signals and infer the same wimp properties. in this work, we review the ideas, methods, and status of direct - detection searches. we focus in particular on extracting wimp physics ( wimp interactions and phase - space distribution ) from direct - detection data in the early discovery days when multiple experiments see of order dozens to hundreds of events. to demonstrate the essential complementarity of different direct - detection experiments in this context, we create mock data intended to represent the data from the near - future generation 2 experiments. we consider both conventional supersymmetry - inspired benchmark points ( with spin - independent and - dependent elastic cross sections just below current limits ), as well as benchmark points for other classes of models ( inelastic and effective - operator paradigms ). we also investigate the effect on parameter estimation of loosening or dropping the assumptions about the local wimp phase - space distribution. we arrive at two main conclusions. firstly, teasing out wimp physics with experiments depends critically on having a wide set of detector target materials, spanning a large range of target nuclear masses and spin - dependent sensitivity. it is also highly desirable to obtain data from low - threshold experiments. secondly, a general reconstruction of the local wimp velocity distribution, which will only be achieved if there are multiple experiments using different target materials, is critical to obtaining a robust and unbiased estimate of the wimp mass. | arxiv:1310.7039 |
multiple object tracking ( mot ) in thermal imaging presents unique challenges due to the lack of visual features and the complexity of motion patterns. this paper introduces an innovative approach to improve mot in the thermal domain by developing a novel box association method that utilizes both thermal object identity and motion similarity. our method merges thermal feature sparsity and dynamic object tracking, enabling more accurate and robust mot performance. additionally, we present a new dataset comprised of a large - scale collection of thermal and rgb images captured in diverse urban environments, serving as both a benchmark for our method and a new resource for thermal imaging. we conduct extensive experiments to demonstrate the superiority of our approach over existing methods, showing significant improvements in tracking accuracy and robustness under various conditions. our findings suggest that incorporating thermal identity with motion data enhances mot performance. the newly collected dataset and source code is available at https : / / github. com / wassimea / thermalmot | arxiv:2411.12943 |
in bankruptcy prediction, the proportion of events is very low, which is often oversampled to eliminate this bias. in this paper, we study the influence of the event rate on discrimination abilities of bankruptcy prediction models. first the statistical association and significance of public records and firmographics indicators with the bankruptcy were explored. then the event rate was oversampled from 0. 12 % to 10 %, 20 %, 30 %, 40 %, and 50 %, respectively. seven models were developed, including logistic regression, decision tree, random forest, gradient boosting, support vector machine, bayesian network, and neural network. under different event rates, models were comprehensively evaluated and compared based on kolmogorov - smirnov statistic, accuracy, f1 score, type i error, type ii error, and roc curve on the hold - out dataset with their best probability cut - offs. results show that bayesian network is the most insensitive to the event rate, while support vector machine is the most sensitive. | arxiv:1803.03756 |
in this paper we develop a dynamic form of bayesian optimization for machine learning models with the goal of rapidly finding good hyperparameter settings. our method uses the partial information gained during the training of a machine learning model in order to decide whether to pause training and start a new model, or resume the training of a previously - considered model. we specifically tailor our method to machine learning problems by developing a novel positive - definite covariance kernel to capture a variety of training curves. furthermore, we develop a gaussian process prior that scales gracefully with additional temporal observations. finally, we provide an information - theoretic framework to automate the decision process. experiments on several common machine learning models show that our approach is extremely effective in practice. | arxiv:1406.3896 |
we study the emergence of phase - locking for winfree oscillators under the effect of inertia. it is known that in a large coupling regime, oscillators governed by the deterministic second - order winfree model with inertia converge to a unique equilibrium. in contrast, in this paper we show the asymptotic emergence of non - trivial synchronization in a suitably small coupling regime. moreover, we study the effect of a new stochastically perturbed winfree system with multiplicative noise and obtain lower estimates in probability for the pathwise emergence of such a synchronizing pattern, provided the noise is sufficiently small. we also provide numerical simulations which hint at the possibility of more general and stronger analytical results. | arxiv:2205.13844 |
successful smart services require seamless integration into existing corporate systems and an interdisciplinary approach that aligns the development of both business models and technical architectures. multi - disciplinarity and cocreating with customers add a layer of complexity but are essential collaboration schemes for validating the value proposition of smart services and building longterm customer loyalty. this paper explores these challenges and distills the design principles for the architectures of technical smart service systems, based on empirical data from architecture projects in two manufacturing companies. these principles contribute to the sparse academic literature on this topic and help practitioners navigate several design trade - offs commonly arising in smart service projects. | arxiv:2502.09270 |
pistons are elementary components of a wide variety of thermal engines, allowing to convert input fuel into rotational motion. here, we propose a single - piston engine where the rotational degree of freedom is effectively realized by the flux of a josephson loop - - a quantum rotor - - while the working volume corresponds to the effective length of a superconducting resonator. our autonomous design implements a carnot cycle, relies solely on standard thermal baths and can be implemented with circuit quantum electrodynamics. we demonstrate how the engine is able to extract a net positive work via its built - in synchronicity using a filter cavity as an effective valve, eliminating the need for external control. | arxiv:1802.05486 |
powerful spectrum decision schemes enable cognitive radios ( crs ) to find transmission opportunities in spectral resources allocated exclusively to the primary users. one of the key effecting factor on the cr network throughput is the spectrum sensing sequence used by each secondary user. in this paper, secondary users ' throughput maximization through finding an appropriate sensing matrix ( sm ) is investigated. to this end, first the average throughput of the cr network is evaluated for a given sm. then, an optimization problem based on the maximization of the network throughput is formulated in order to find the optimal sm. as the optimum solution is very complicated, to avoid its major challenges, three novel sub optimum solutions for finding an appropriate sm are proposed for various cases including perfect and non - perfect sensing. despite of having less computational complexities as well as lower consumed energies, the proposed solutions perform quite well compared to the optimum solution ( the optimum sm ). the structure and performance of the proposed sm setting schemes are discussed in detail and a set of illustrative simulation results is presented to validate their efficiencies. | arxiv:1111.4624 |
in the context of quantum gravity, we clarify entanglement calculations on spin networks : we distinguish the gauge - invariant entanglement between intertwiners located at the nodes and the entanglement between spin states located on the network ' s links. we compute explicitly these two notions of entanglement between neighboring nodes and show that they are always related to the typical $ \ ln ( 2j + 1 ) $ term depending on the spin $ j $ living on the link between them. this $ \ ln ( 2j + 1 ) $ contribution comes from looking at non - gauge invariant states, thus we interpret it as gauge - breaking and unphysical. in particular, this confirms that pure spin network basis states do not carry any physical entanglement, so that true entanglement and correlations in loop quantum gravity comes from spin or intertwiner superpositions. | arxiv:1709.08511 |
the status of coupling constant unification - - assuming the validity of the standard model or of its minimal supersymmetric extension at high energies - - and of relations between various yukawa couplings ( assuming the supersymmetri extension ) which are implied in certain grand - unified theories, are studied in detail. theoretical uncertainties in the calculations are emphasized, and low - energy constraints and predictions are derived. in particular, we find that bottom - tau unification favors a higgs boson lighter than 110 gev. the structure of the vacuum in the model studied is also discussed. implications of embedding supersymmetric models in grand - unified theories are further explored and are shown to affect the soft supersymmetry breaking mass parameters of the models, and thus the spectrum at low - energy. | arxiv:hep-ph/9411378 |
synthetic data is a powerful tool in training data hungry deep learning algorithms. however, to date, camera - based physiological sensing has not taken full advantage of these techniques. in this work, we leverage a high - fidelity synthetics pipeline for generating videos of faces with faithful blood flow and breathing patterns. we present systematic experiments showing how physiologically - grounded synthetic data can be used in training camera - based multi - parameter cardiopulmonary sensing. we provide empirical evidence that heart and breathing rate measurement accuracy increases with the number of synthetic avatars in the training set. furthermore, training with avatars with darker skin types leads to better overall performance than training with avatars with lighter skin types. finally, we discuss the opportunities that synthetics present in the domain of camera - based physiological sensing and limitations that need to be overcome. | arxiv:2110.04902 |
drones as advanced cyber - physical systems are undergoing a transformative shift with the advent of vision - based learning, a field that is rapidly gaining prominence due to its profound impact on drone autonomy and functionality. different from existing task - specific surveys, this review offers a comprehensive overview of vision - based learning in drones, emphasizing its pivotal role in enhancing their operational capabilities under various scenarios. we start by elucidating the fundamental principles of vision - based learning, highlighting how it significantly improves drones ' visual perception and decision - making processes. we then categorize vision - based control methods into indirect, semi - direct, and end - to - end approaches from the perception - control perspective. we further explore various applications of vision - based drones with learning capabilities, ranging from single - agent systems to more complex multi - agent and heterogeneous system scenarios, and underscore the challenges and innovations characterizing each area. finally, we explore open questions and potential solutions, paving the way for ongoing research and development in this dynamic and rapidly evolving field. with growing large language models ( llms ) and embodied intelligence, vision - based learning for drones provides a promising but challenging road towards artificial general intelligence ( agi ) in 3d physical world. | arxiv:2312.05019 |
the dielectric properties of bi $ _ 2 $ te $ _ 3 $, a layered compound crystallizing in a rhombohedral structure, are investigated by means of first - principles calculations at the random phase approximation level. a special attention is devoted to the anisotropy in the dielectric function and to the local field effects that strongly renormalize the optical properties in the uv - visible range when the electric field is polarized along the stacking axis. furthermore, both the born effective charges for each atom and the zone center phonon frequencies and eigenvectors needed to describe the dielectric response in the infrared range are computed. our theoretical near - normal incidence reflectivity spectras in both the uv - visible and infrared range are in fairly good agreement with the experimental spectras, provided that the free carriers drude contribution arising from defects is included in the infrared response. the anisotropic plasmon frequencies entering the drude model are computed within the rigid band approximation, suggesting that a measurement of the reflectivity in the infrared range for both polarizations might allow to infer not only the type of doping but also the level of doping. | arxiv:2306.15398 |
federated learning ( fl ) enables multiple clients to collaboratively train an accurate global model while protecting clients ' data privacy. however, fl is susceptible to byzantine attacks from malicious participants. although the problem has gained significant attention, existing defenses have several flaws : the server irrationally chooses malicious clients for aggregation even after they have been detected in previous rounds ; the defenses perform ineffectively against sybil attacks or in the heterogeneous data setting. to overcome these issues, we propose mab - rfl, a new method for robust aggregation in fl. by modelling the client selection as an extended multi - armed bandit ( mab ) problem, we propose an adaptive client selection strategy to choose honest clients that are more likely to contribute high - quality updates. we then propose two approaches to identify malicious updates from sybil and non - sybil attacks, based on which rewards for each client selection decision can be accurately evaluated to discourage malicious behaviors. mab - rfl achieves a satisfying balance between exploration and exploitation on the potential benign clients. extensive experimental results show that mab - rfl outperforms existing defenses in three attack scenarios under different percentages of attackers. | arxiv:2204.13256 |
a highly pure and stable single - photon source is prepared that comprises a well - designed pillar array in which each pillar contains only a few inas quantum dots. a nano - pillar in this array is in direct contact with a fiber end surface and cooled in a liquid - he bath. auto - correlation measurement shows that this source provides an average $ g ^ { ( 2 ) } ( 0 ) $ value of 0. 0174 in the measured excitation - power range. this photon source and fiber coupling are quite rigid against external disturbances such as cooling - heating cycles and vibration, with long - term stability. | arxiv:1707.03131 |
we present a new flexible estimator for comparing theoretical templates for the predicted bispectrum of the cmb anisotropy to observations. this estimator, based on binning in harmonic space, generalizes the optimal estimator of komatsu, spergel, and wandelt by allowing an adjustable weighting scheme for masking possible foreground and other contaminants and detecting particular noteworthy features in the bispectrum. the utility of this estimator is illustrated by demonstrating how acoustic oscillations in the bispectrum and other details of the bispectral shape could be detected in the future planck data provided that fnl is sufficiently large. the character and statistical weight of the acoustic oscillations and the decay tail are described in detail. | arxiv:0911.1642 |
dems have been used to experimental studying the temporal evolution of the march maximum of fluxes of near - earth daemons. it is shown that part of objects from near - earth almost circular heliocentric orbits ( neachos ), from which a rather intense flux proceeds during only about four weeks, forms in the second half of march the population in geocentric earth - surface - crossing orbits ( gescos ). the resistance of the earth ' s matter results in that gesco objects sink into the earth ' s interior, so that the gesco population nearly disappears by the end of april. | arxiv:1206.5758 |
this paper concerns some spectral properties of the scalar dynamical system defined by a linear delay - differential equation with two positive delays. more precisely, the existing links between the delays and the maximal multiplicity of the characteristic roots are explored, as well as the dominancy of such roots compared with the spectrum localization. as a by - product of the analysis, the pole placement issue is revisited with more emphasis on the role of the delays as control parameters in defining a partial pole placement guaranteeing the closed - loop stability with an appropriate decay rate of the corresponding dynamical system. | arxiv:2204.12821 |
external magnetic fields conventionally suppress superconductivity, both by orbital and paramagnetic effects. a recent experiment has shown that in a bernal stacked bilayer graphene system, the opposite occurs - - a finite critical magnetic field is necessary to observe superconducting features occurring in the vicinity of a magnetic phase transition. we propose an extraordinary electronic - correlation - driven mechanism by which this anomalous superconductivity manifests. specifically, the electrons tend to avoid band occupations near high density of states regions due to their mutual repulsion. considering the nature of spontaneous symmetry breaking involved, we dub this avoidance stoner blockade. we show how a magnetic field softens this blockade, allowing weak superconductivity to take place, consistent with experimental findings. our principle prediction is that a small reduction of the coulomb repulsion would result in sizable superconductivity gains, both in achieving higher critical temperatures and expanding the superconducting regime. within the theory we present, magnetic field and spin - orbit coupling of the ising type have a similar effect on the bernal stacked bilayer graphene system, elucidating the emergence of superconductivity when the system is proximitized to a $ \ rm wse _ 2 $ substrate. we further demonstrate in this paper the sensitivity of superconductivity to disorder in the proposed scenario. we find that a disorder that does not violate anderson ' s theorem may still induce a reduction of $ t _ c $ through its effect on the density of states, establishing the delicate nature of the bernal bilayer graphene superconductor. | arxiv:2303.04176 |
we give a general way of representing the crystal ( base ) corresponding to the intgrable highest weight modules of quantum kac - moody algebras, which is called polyhedral realizations. this is applied to describe explicitly the crystal bases of integrable highest weight modules for arbitrary rank 2 kac - moody algebra cases, the classical a _ n - case and the affine a ^ { ( 1 ) } _ { n - 1 } - case. | arxiv:math/9806085 |
we describe $ { \ rm forb } \ { k _ { 1, 3 }, \ bar { k _ { 1, 3 } } \ } $, the class of graphs $ g $ such that $ g $ and its complement $ \ bar { g } $ are claw - free. with few exceptions, it is made of graphs whose connected components consist of cycles of length at least 4, paths, and of the complements of these graphs. considering the hypergraph $ { \ mathcal h } ^ { ( 3 ) } ( g ) $ made of the 3 - element subsets of the vertex set of a graph $ g $ on which $ g $ induces a clique or an independent subset, we deduce from above a description of the boolean sum $ g \ dot { + } g ' $ of two graphs $ g $ and $ g ' $ giving the same hypergraph. we indicate the role of this latter description in a reconstruction problem of graphs up to complementation. | arxiv:1309.1835 |
the most well - known conjecture in the context of matroid secretary problems claims the existence of a constant - factor approximation applicable to any matroid. whereas this conjecture remains open, modified forms of it were shown to be true, when assuming that the assignment of weights to the secretaries is not adversarial but uniformly random ( soto [ soda 2011 ], oveis gharan and vondr \ ' ak [ esa 2011 ] ). however, so far, there was no variant of the matroid secretary problem with adversarial weight assignment for which a constant - factor approximation was found. we address this point by presenting a 9 - approximation for the \ emph { free order model }, a model suggested shortly after the introduction of the matroid secretary problem, and for which no constant - factor approximation was known so far. the free order model is a relaxed version of the original matroid secretary problem, with the only difference that one can choose the order in which secretaries are interviewed. furthermore, we consider the classical matroid secretary problem for the special case of laminar matroids. only recently, a constant - factor approximation has been found for this case, using a clever but rather involved method and analysis ( im and wang, [ soda 2011 ] ) that leads to a 16000 / 3 - approximation. this is arguably the most involved special case of the matroid secretary problem for which a constant - factor approximation is known. we present a considerably simpler and stronger $ 3 \ sqrt { 3 } e \ approx 14. 12 $ - approximation, based on reducing the problem to a matroid secretary problem on a partition matroid. | arxiv:1207.1333 |
[ context ] the growing software development market has increased the demand for qualified professionals in software engineering ( se ). to this end, companies must enhance their recruitment and selection ( r & s ) processes to maintain high quality teams, including opening opportunities for beginners, such as trainees and interns. however, given the various judgments and sociotechnical factors involved, this complex process of r & s poses a challenge for recent graduates seeking to enter the market. [ objective ] this paper aims to identify a set of anti - patterns and recommendations for early career se professionals concerning r & s processes. [ method ] under an exploratory and qualitative methodological approach, we conducted six online focus groups with 18 recruiters with experience in r & s in the software industry. [ results ] after completing our qualitative analysis, we identified 12 anti - patterns and 31 actionable recommendations regarding the hiring process focused on entry level se professionals. the identified anti - patterns encompass behavioral and technical dimensions innate to r & s processes. [ conclusion ] these findings provide a rich opportunity for reflection in the se industry and offer valuable guidance for early - career candidates and organizations. from an academic perspective, this work also raises awareness of the intersection of human resources and se, an area with considerable potential to be expanded in the context of cooperative and human aspects of se. | arxiv:2406.02487 |
quantitative descriptions of strongly correlated materials pose a considerable challenge in condensed matter physics and chemistry. a promising approach to address this problem is quantum embedding methods. in particular, the dynamical mean - field theory ( dmft ) maps the original system to an effective quantum impurity model comprising correlated orbitals embedded in an electron bath. the biggest bottleneck in dmft calculations is numerically solving the quantum impurity model, i. e., computing green ' s function. past studies have proposed theoretical methods to compute green ' s function of a quantum impurity model in polynomial time using a quantum computer. so far, however, efficient methods for computing the imaginary - time green ' s functions have not been established despite the advantages of the imaginary - time formulation. we propose a quantum - classical hybrid algorithm for computing imaginary - time green ' s functions on quantum devices with limited hardware resources by applying the variational quantum simulation. using a quantum circuit simulator, we verified this algorithm by computing green ' s functions for a dimer model as well as a four - site impurity model obtained by dmft calculations of the single - band hubbard model, although our method can be applied to general imaginary - time correlation functions. | arxiv:2112.02764 |
the spectroscopic analysis of 117 serendipitous sources in the hellas2xmm 1df ( 1 degree field ) survey is described. of these, 106 sources, of which 86 % have a spectroscopic redshift, are used to evaluate the fraction of x - ray absorbed ( log nh > 22 ) active galactic nuclei ( agn ) in the 2 - - 10 kev flux range 0. 8 - 20e - 14 erg / cm2 / s. this fraction turns out lower than what is predicted by two well known cosmic x - ray background synthesis models, and the discrepancy is significant at the 99. 999 % level. this result consolidates the findings recently obtained by other authors. in the flux interval explored, the data are consistent with an intrinsic distribution of the absorbing columns ( flat per decade above lognh > 21 ) independent of luminosity and redshift, together with an agn luminosity function evolving purely in luminosity. it is shown that, on the other hand, extrapolation to lower fluxes fails to reproduce the results inferred from the chandra deep field north survey. it is found that about 40 % of the high luminosity sources in our sample have best fit lognh > 22, and the surface density of these x - ray obscured qsos can then be estimated at about 48 per square degree, at the flux limit of ~ 1e - 14 } erg / cm2 / s of the hellas2xmm 1df survey. as a side issue, 5 or 6 out of 60 sources, that is about 10 %, identified with broad line agn, turn out to be affected by lognh > 22 absorption. | arxiv:astro-ph/0404044 |
given a weak kac system with duality $ ( \ mathcal { h }, v, u ) $ arising from regular $ \ mathrm { c } ^ { * } $ - algebraic locally compact quantum group $ ( \ mathcal { g }, \ delta ) $, a $ \ mathrm { c } ^ { * } $ - algebra $ a $, and a sufficiently well - behaved coaction $ \ alpha $, we construct natural lattice isomorphisms from the coaction invariant ideals of $ a $ to the dual coaction invariant ideals of full and reduced crossed products associated to $ ( \ mathcal { h }, v, u ) $. in particular, these lattice isomorphisms are determined by either the maximality or normality of the coaction $ \ alpha $. this result directly generalizes the main theorem of gillespie, kaliszewski, quigg, and williams in arxiv : 2406. 06780, which in turn generalized an older ideal correspondence result of gootman and lazar for locally compact amenable groups. throughout, we also develop basic conventions and motivate through elementary examples how crossed product $ \ mathrm { c } ^ { * } $ - algebras by quantum groups generalize the classical crossed product theory. | arxiv:2504.11677 |
in the context of the modified becke - johnson ( mbj ) potential, we recently underlined that $ \ bar { g } $, the average of $ \ left \ vert \ nabla \ rho \ right \ vert / \ rho $ in the unit cell, has markedly different values in transition - metal oxides and pure transition metals [ tran et al., j. appl. phys. 126, 110902 ( 2019 ) ]. however, since $ \ bar { g } $ is a constant it is not able to provide local information about a particular atom in the system. furthermore, while $ \ overline { g } $ can be used only for periodic bulk solids, a local ( i. e., position - dependent ) version would allow us to consider also low - dimensional systems and interfaces. such a local function has been proposed by rauch et al. [ j. chem. theory comput. 16, 2654 ( 2020 ) ] for the local mbj potential. actually, a local version of $ \ overline { g } $, or of another similar quantity like the reduced density gradient $ \ overline { s } $, could also be used in the framework of other methods. here, we explored the idea to use such a local function $ \ tilde { g } $ ( or $ \ tilde { s } $ ), defined as the average of $ g $ ( or $ s $ ) over a certain region around a transition - metal atom, to estimate the degree of on - site correlation on this atom. we found a large difference in our correlation estimators between non - correlated and correlated materials, proving its usefulness and reliability. our estimators can subsequently be used to determine whether or not a hubbard $ u $ on - site correction in the dft + $ u $ method should be applied to a particular atom. this is particularly interesting in cases where the degree of correlation of the transition - metal atoms is not clear, like interfaces between correlated and non - correlated materials or oxygen - covered metal surfaces. in such cases, our estimators could also be used for an interpolation of $ u $ between correlated and non - correlated atoms. | arxiv:2108.07687 |
wirelessly powered backscatter communication ( wpbc ) has been identified as a promising technology for low - power communication systems, which can reap the benefits of energy beamforming to improve energy transfer efficiency. however, existing studies on energy beamforming fail to simultaneously take energy supply and information transfer in wpbc into account. this paper takes the first step to fill this gap, by considering the restrictive relationship between the energy harvesting rate and achievable rate with estimated backscatter channel state information ( bs - csi ). to ensure reliable communication and user fairness, we formulate the energy beamforming design as a max - min optimization problem by maximizing the minimum achievable rate for all backscatter tags subject to the energy constraint. we derive the closed - form expression of the energy harvesting rate, as well as the lower bound of the achievable rate for maximum - ratio combining ( mrc ) and zero - forcing ( zf ) receivers. our numerical results indicate that our scheme significantly outperforms state - of - the - art energy beamforming schemes. additionally, the achievable rate of our scheme approaches more than $ 90 \ % $ of the rate limit achieved via beamforming with perfect csi for both receivers. | arxiv:2011.01533 |
the united rest mass and charge of a particle correspond to the two forms of the same regularity of the unified nature of its ultimate structure. each of them contains the electric, weak, strong and the gravitational contributions. as a consequence, the force of an attraction among the two neutrinos and force of their repulsion must be defined from the point of view of any of the existing types of the actions. therefore, to understand the nature of the micro world interaction at the fundamental level, one must use the fact that each of the four types of well known forces includes both a kind of the newton and a kind of the coulomb components. the opinion has been spoken that the existence of the gravitational parts of the united rest mass and charge would imply the availability of such a fifth force which come forwards in the system as a unified whole. | arxiv:hep-ph/0401230 |
let $ \ mathbb f $ denote an algebraically closed field and assume that $ q \ in \ mathbb f $ is a primitive $ d ^ { \ rm \, th } $ root of unity with $ d \ not = 1, 2, 4 $. the universal askey - - wilson algebra $ \ triangle _ q $ is a unital associative $ \ mathbb f $ - algebra defined by generators and relations. the generators are $ a, b, c $ and the relations assert that each of \ begin { gather * } a + \ frac { qbc - q ^ { - 1 } cb } { q ^ 2 - q ^ { - 2 } }, \ qquad b + \ frac { qca - q ^ { - 1 } ac } { q ^ 2 - q ^ { - 2 } }, \ qquad c + \ frac { qab - q ^ { - 1 } ba } { q ^ 2 - q ^ { - 2 } } \ qquad \ end { gather * } commutes with $ a, b, c $. we show that every finite - dimensional irreducible $ \ triangle _ q $ - module is of dimension less than or equal to $ $ \ left \ { \ begin { array } { ll } d \ quad & \ hbox { if $ d $ is odd } ; \ newline d / 2 \ quad & \ hbox { if $ d $ is even }. \ end { array } \ right. $ $ moreover we provide an example to show that the bound is tight. | arxiv:1906.01776 |
we demonstrate that the true qcd axion that solves the strong cp problem can be found in all generality outside the customary standard qcd band, with qcd being the sole source of peccei - quinn breaking. the essential reason is that the basis of axion - gluon interactions does not need to coincide with the mass basis. specifically, we consider the case in which the qcd axion field is not the only singlet scalar in nature but it mixes with other singlet scalars ( besides the $ \ eta ' $ ). we determine the exact mathematical condition for an arbitrary $ n $ - scalar potential to be peccei - quinn invariant. such potentials provide extra sources of mass for the customary axion without enlarging the standard model gauge symmetry. the contribution to the axion mass stemming from the qcd topological susceptibility is shown to be shared then among the $ n $ axion eigenstates through a precise sum rule. their location can only be displaced to the right of the standard qcd band. we demonstrate that the axion closest to this band can be displaced from it by a factor of $ \ sqrt { n } $ at most, and this corresponds to the case in which all axion signals are maximally deviated. conversely, if one axion is found on the standard qcd band, the other eigenstates will be out of experimental reach. our results imply that any alp experiment which finds a signal outside the standard qcd axion band can be solving the strong cp problem within qcd, with the associated $ n - 1 $ excitations to be found in an area of parameter space that we determine. we illustrate the results and phenomenology in some particular cases. | arxiv:2305.15465 |
golay complementary pairs ( gcps ) and complete complementary codes ( cccs ) have found a wide range of practical applications in coding, signal processing and wireless communication due to their ideal correlation properties. in fact, binary cccs have special advantages in spread spectrum communication due to their simple modulo - 2 arithmetic operation, modulation and correlation simplicity, but they are limited in length. in this paper, we present a direct construction of gcps, mutually orthogonal complementary sets ( mocss ) and binary cccs of non - power of two lengths to widen their application in the recent field. first, a generalised boolean function ( gbf ) based truncation technique has been used to construct gcps of non - power of two lengths. then complementary sets ( css ) and mocss of lengths of the form $ 2 ^ { m - 1 } + 2 ^ { m - 3 } $ ( $ m \ geq 5 $ ) and $ 2 ^ { m - 1 } + 2 ^ { m - 2 } + 2 ^ { m - 4 } $ ( $ m \ geq 6 $ ) are generated by gbfs. finally, binary cccs with desired lengths are constructed using the union of mocss. the row and column sequence peak to mean envelope power ratio ( pmepr ) has been investigated and compared with existing work. the column sequence pmepr of resultant cccs can be effectively upper bounded by $ 2 $. | arxiv:2109.08567 |
this paper shows that one can be competitive with the k - means objective while operating online. in this model, the algorithm receives vectors v _ 1,..., v _ n one by one in an arbitrary order. for each vector the algorithm outputs a cluster identifier before receiving the next one. our online algorithm generates ~ o ( k ) clusters whose k - means cost is ~ o ( w * ). here, w * is the optimal k - means cost using k clusters and ~ o suppresses poly - logarithmic factors. we also show that, experimentally, it is not much worse than k - means + + while operating in a strictly more constrained computational model. | arxiv:1412.5721 |
two key challenges within reinforcement learning involve improving ( a ) agent learning within environments with sparse extrinsic rewards and ( b ) the explainability of agent actions. we describe a curious subgoal focused agent to address both these challenges. we use a novel method for curiosity produced from a generative adversarial network ( gan ) based model of environment transitions that is robust to stochastic environment transitions. additionally, we use a subgoal generating network to guide navigation. the explainability of the agent ' s behavior is increased by decomposing complex tasks into a sequence of interpretable subgoals that do not require any manual design. we show that this method also enables the agent to solve challenging procedurally - generated tasks that contain stochastic transitions above other state - of - the - art methods. | arxiv:2104.06630 |
a characterization of dynamically defined zeta functions is presented. it comprises a list of axioms, natural extension of the one which characterizes topological degree, and a uniqueness theorem. lefschetz zeta function is the main ( and proved unique ) example of such zeta functions. another interpretation of this function arises from the notion of symmetric product from which some corollaries and applications are obtained. | arxiv:1605.08725 |
spin - charge conversion by inverse spin hall effect or inverse rashba - edelstein effect is prevalent in spintronics but dissipative. we propose a dissipationless spin - charge conversion mechanism by an excitonic pseudospin superfluid in an electron - hole double layer system. magnetic exchange fields lift singlet - triplet degeneracy of interlayer exciton levels in the double layer system. condensation of the singlet - triplet hybridized excitons breaks both a u ( 1 ) gauge symmetry and a pseudospin rotational symmetry around the fields, leading to spin - charge coupled superflow in the system. we demonstrate the mechanism by deriving spin - charge coupled josephson equations for the excitonic superflow from a coupled quantum - dot model. | arxiv:2108.00409 |
we present here preliminary results concerning 32 stars identified as main gamma doradus candidates by the corot variable classifier ( cvc ) among the 4 first fields of the exoplanet ccds. | arxiv:0909.0140 |
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