text
stringlengths 1
3.65k
| source
stringlengths 15
79
|
|---|---|
emergence and causality are two fundamental concepts for understanding complex systems. they are interconnected. on one hand, emergence refers to the phenomenon where macroscopic properties cannot be solely attributed to the cause of individual properties. on the other hand, causality can exhibit emergence, meaning that new causal laws may arise as we increase the level of abstraction. causal emergence theory aims to bridge these two concepts and even employs measures of causality to quantify emergence. this paper provides a comprehensive review of recent advancements in quantitative theories and applications of causal emergence. two key problems are addressed : quantifying causal emergence and identifying it in data. addressing the latter requires the use of machine learning techniques, thus establishing a connection between causal emergence and artificial intelligence. we highlighted that the architectures used for identifying causal emergence are shared by causal representation learning, causal model abstraction, and world model - based reinforcement learning. consequently, progress in any of these areas can benefit the others. potential applications and future perspectives are also discussed in the final section of the review.
|
arxiv:2312.16815
|
in 1973, katona raised the problem of determining the maximum number of subsets in a separating cover on n elements. the answer to katona ' s question turns out to be the inverse to the answer to a much simpler question : what is the largest integer which is the product of positive integers with sum n? we give a combinatorial explanation for this relationship, via moon and moser ' s answer to a question of erdos : how many maximal independent sets can a graph on n vertices have? we conclude by showing how moon and moser ' s solution also sheds light on a problem of mahler and popken ' s about the complexity of integers.
|
arxiv:0911.4204
|
we explore the possibility of detecting lepton flavour violation, now a well established experimental fact, at the international linear collider. using a model independent approach we conclude that, given all experimental constraints available, there is still room to detect lepton flavour violation at the ilc.
|
arxiv:0709.2818
|
real and momentum space spectrally resolved images of microcavity polariton emission in the regime of condensation are investigated under non resonant excitation using a laser source with reduced intensity fluctuations on the timescale of the exciton lifetime. we observe that the polariton emission consists of many macroscopically occupied modes. lower energy modes are strongly localized by the photonic potential disorder on a scale of few microns. higher energy modes have finite k - vectors and are delocalized over 10 - 15 microns. all the modes exhibit long range spatial coherence comparable to their size. we provide a theoretical model describing the behavior of the system with the results of the simulations in good agreement with the experimental observations. we show that the multimode emission of the polariton condensate is a result of its nonequilibrium character, the interaction with the local photonic potential and the reduced intensity fluctuations of the excitation laser.
|
arxiv:0903.1570
|
the nonlinear evolution of the quantum two - stream instability in a plasma with counter - streaming electron beams is studied. it is shown that in the long - wave limit the nonlinear stage of the instability can be described by the elliptic nonlinear string equation. we present two types of the nonlinear solutions. the first one is an unstable nonlinear mode that is continuously related with the growing linear solution and the second one is a pulsating soliton. we show that both of these solutions blow up in a finite time.
|
arxiv:2007.15694
|
in the present work, the problem about shadow, generalized on domains of space $ \ mathbb { r } ^ n $, $ n \ le 3 $, is investigated. here the shadow problem means to find the minimal number of balls satisfying some conditions an such that every line passing through the given point intersects at least one ball of the collection. it is proved that to generate the shadow at every given point of any domain of the space $ \ mathbb { r } ^ 3 $ ( $ \ mathbb { r } ^ 2 $ ) with collection of mutually non - overlapping closed or open balls which do not hold the point and with centers on the boundary of the domain, it is sufficient to have four balls.
|
arxiv:1602.01300
|
existing domain generalization methods for lidar semantic segmentation under adverse weather struggle to accurately predict " things " categories compared to " stuff " categories. in typical driving scenes, " things " categories can be dynamic and associated with higher collision risks, making them crucial for safe navigation and planning. recognizing the importance of " things " categories, we identify their performance drop as a serious bottleneck in existing approaches. we observed that adverse weather induces degradation of semantic - level features and both corruption of local features, leading to a misprediction of " things " as " stuff ". to mitigate these corruptions, we suggest our method, ntn - segment things for no - accident. to address semantic - level feature corruption, we bind each point feature to its superclass, preventing the misprediction of things classes into visually dissimilar categories. additionally, to enhance robustness against local corruption caused by adverse weather, we define each lidar beam as a local region and propose a regularization term that aligns the clean data with its corrupted counterpart in feature space. ntn achieves state - of - the - art performance with a + 2. 6 miou gain on the semantickitti - to - semanticstf benchmark and + 7. 9 miou on the semanticposs - to - semanticstf benchmark. notably, ntn achieves a + 4. 8 and + 7. 9 miou improvement on " things " classes, respectively, highlighting its effectiveness.
|
arxiv:2503.15910
|
a unifying slipping and sticking frictional impact model for multibody systems in contact with a frictional surface is presented. it is shown that the model can lead to energetic consistency in both slip state and stick state upon imposing specific constraints on the coefficient of friction ( cof ) and the coefficient of restitution ( cor ). a discriminator in the form of a quadratic function of the pre - impact velocity is introduced based on isotropic coulomb constraint such that its sign determines whether the impact occurs in the sticking mode or in the slipping mode just prior to the contact. solving the zero - crossings of such a function in terms of the cof and the cor variables leads to another discriminator called critical cof, which is the lowest static cof required to prevent the subsequent impulse vector violating the isotropic friction cone constraint. investigating conditions for the energetically consistent impact model reveals that the maximum values of either cor or cof should be limited depending on stick state or slip state. furthermore, it is shown that these upper - bound limits in conjunction with the introduced critical cof variable can be used to specify the admissible set of cor and cof parameters, which can be represented by two distinct regions in the plan of cof versus cor.
|
arxiv:2109.00333
|
the main deficiency of the algorithms running on digital computers nowadays is their inability to change themselves during the execution. in line with this, the paper introduces the so - called replicated algorithms, inspired by the concept of developing a human brain. similar to the human brain, where the process of thinking is strongly parallel, replicated algorithms, incorporated into a population, are also capable of replicating themselves and solving problems in parallel. they operate as a model for mapping the known input to a known output. in our preliminary study, these algorithms are built as sequences of arithmetic operators, applied for calculating arithmetic expressions, while their behavior showed that they can operate in the condition of open - ended evolution.
|
arxiv:2304.13524
|
we consider the positivity bounds for wimp scalar dark matter with effective higgs - portal couplings up to dimension - 8 operators. taking the superposed states for standard model higgs and scalar dark matter, we show that the part of the parameter space for the effective couplings, otherwise unconstrained by phenomenological bounds, is ruled out by the positivity bounds on the dimension - 8 derivative operators. we find that dark matter relic density, direct and indirect detection and lhc constraints are complementary to the positivity bounds in constraining the effective higgs - portal couplings. in the effective theory obtained from massive graviton or radion, there appears a correlation between dimension - 8 operators and other effective higgs - portal couplings for which the strong constraint from direct detection can be evaded. nailing down the parameter space mainly by relic density, direct detection and positivity bounds, we find that there are observable cosmic ray signals coming from the dark matter annihilations into a pair of higgs bosons, $ ww $ or $ zz $.
|
arxiv:2302.02879
|
molecular magnets based on heavy transition metals have recently attracted significant interest in the quest for novel magnetic properties. for systems with an odd number of valence electrons per molecule, high or low molecular spin states are typically expected in the double exchange or quasi - molecular orbital limits respectively. in this work, we use bulk characterization, muon spin relaxation, neutron diffraction, and inelastic neutron scattering to identify a rare intermediate spin - 3 / 2 per dimer state in the 6h - perovskite ba $ _ 3 $ laru $ _ 2 $ o $ _ 9 $ that cannot be understood in a double exchange or quasi - molecular orbital picture and instead arises from orbital - selective mott insulating behavior at the molecular level. our measurements are also indicative of collinear stripe magnetic order below $ t _ n $ = 26 ( 1 ) k for these molecular spin - 3 / 2 degrees - of - freedom, which is consistent with expectations for an ideal triangular lattice with significant next nearest neighbor in - plane exchange. finally, we present neutron diffraction and raman scattering data under applied pressure that reveal low - lying structural and spin state transitions at modest pressures p $ \ le $ 1 gpa, which highlights the delicate balance between competing energy scales in this system.
|
arxiv:2004.00661
|
a well - trained deep neural network is shown to gain capability of simultaneously restoring two kinds of images, which are completely destroyed by two distinct scattering medias respectively. the network, based on the u - net architecture, can be trained by blended dataset of speckles - reference images pairs. we experimentally demonstrate the power of the network in reconstructing images which are strongly diffused by glass diffuser or multi - mode fiber. the learning model further shows good generalization ability to reconstruct images that are distinguished from the training dataset. our work facilitates the study of optical transmission and expands machine learning ' s application in optics.
|
arxiv:1809.07706
|
the paper deals with the existence of standing wave solutions for the schr \ " odinger - poisson system with prescribed mass in dimension $ n = 2 $. this leads to investigate the existence of normalized solutions for an integro - differential equation involving a logarithmic convolution potential, namely $ $ \ left \ { \ begin { aligned } - \ delta u & + \ lambda u + \ gamma \ bigl ( \ log { | \ cdot | } * | u | ^ 2 \ bigr ) u = a | u | ^ { p - 2 } u \ qquad \ text { in $ \ mathbb r ^ 2 $, } \ \ & \ int _ { \ mathbb r ^ 2 } | u | ^ 2 dx = c \ end { aligned } \ right. $ $ where $ c > 0 $ is a given real number. under different assumptions on $ \ gamma \ in \ mathbb r $, $ a \ in \ mathbb r $, $ p > 2 $, we prove several existence and multiplicity results. here $ \ lambda \ in \ mathbb r $ appears as a lagrange parameter and is part of the unknowns. with respect to the related higher dimensional cases, the presence of the logarithmic kernel, which is unbounded from above and below, makes the structure of the solution set much richer and it forces the implementation of new ideas to catch the normalized solutions.
|
arxiv:1901.02421
|
business process enactment is generally supported by information systems that record data about process executions, which can be extracted as event logs. predictive process monitoring is concerned with exploiting such event logs to predict how running ( uncompleted ) cases will unfold up to their completion. in this paper, we propose a predictive process monitoring framework for estimating the probability that a given predicate will be fulfilled upon completion of a running case. the predicate can be, for example, a temporal logic constraint or a time constraint, or any predicate that can be evaluated over a completed trace. the framework takes into account both the sequence of events observed in the current trace, as well as data attributes associated to these events. the prediction problem is approached in two phases. first, prefixes of previous traces are clustered according to control flow information. secondly, a classifier is built for each cluster using event data to discriminate between fulfillments and violations. at runtime, a prediction is made on a running case by mapping it to a cluster and applying the corresponding classifier. the framework has been implemented in the prom toolset and validated on a log pertaining to the treatment of cancer patients in a large hospital.
|
arxiv:1506.01428
|
the extragalactic distance scale builds directly on the cepheid period - luminosity ( pl ) relation as delineated by the sample of cepheids in the large magellanic cloud ( lmc ). however, the lmc is a dwarf irregular galaxy, quite different from the massive spiral galaxies used for calibrating the extragalactic distance scale. recent investigations suggest that not only the zero - point but also the slope of the milky way pl relation differ significantly from that of the lmc, casting doubts on the universality of the cepheid pl relation. we want to make a differential comparison of the pl relations in the two galaxies by delineating the pl relations using the same method, the infrared surface brightness method ( irsb ), and the same precepts. the irsb method is a baade - wesselink type method to determine individual distances to cepheids. we apply a newly revised calibration of the method as described in an accompanying paper ( paper i ) to 36 lmc and five smc cepheids and delineate new pl relations in the v, i, j, & k bands as well as in the wesenheit indices in the optical and near - ir. we present 509 new and accurate radial velocity measurements for a sample of 22 lmc cepheids, enlarging our earlier sample of 14 stars to include 36 lmc cepheids. the new calibration of the irsb method is directly tied to the recent hst parallax measurements to ten milky way cepheids, and we find a lmc barycenter distance modulus of 18. 45 + - 0. 04 ( random error only ) from the 36 individual lmc cepheid distances. we find a significant metallicity effect on the wvi index gamma ( wvi ) = - 0. 23 + - 0. 10 mag / dex as well as an effect on the slope. the k - band pl relation on the other hand is found to be an excellent extragalactic standard candle being metallicity insensitive in both slope and zero - point and at the same time being reddening insensitive and showing the least internal dispersion.
|
arxiv:1109.2016
|
we consider the problem of mean estimation assuming only finite variance. we study a new class of mean estimators constructed by integrating over random noise applied to a soft - truncated empirical mean estimator. for appropriate choices of noise, we show that this can be computed in closed form, and utilizing relative entropy inequalities, these estimators enjoy deviations with exponential tails controlled by the second moment of the underlying distribution. we consider both additive and multiplicative noise, and several noise distribution families in our analysis. furthermore, we empirically investigate the sensitivity to the mean - standard deviation ratio for numerous concrete manifestations of the estimator class of interest. our main take - away is that an inexpensive new estimator can achieve nearly sub - gaussian performance for a wide variety of data distributions.
|
arxiv:1906.10300
|
the lamb shift results from the coupling of an atom to vacuum fluctuations of quantum fields, so corrections are expected to arise when the spacetime is curved since the vacuum fluctuations are modified by the presence of spacetime curvature. here, we calculate the curvature - induced correction to the lamb shift outside a spherically symmetric object and demonstrate that this correction can be remarkably significant outside a compact massive astrophysical body. for instance, for a neutron star or a stellar mass black hole, the correction is $ \ sim $ 25 % at a radial distance of $ 4gm / c ^ 2 $, $ \ sim $ 16 % at $ 10gm / c ^ 2 $ and as large as $ \ sim $ 1. 6 % even at $ 100gm / c ^ 2 $, where $ m $ is the mass of the object, $ g $ the newtonian constant, and $ c $ the speed of light. in principle, we can look at the spectra from a distant compact super - massive body to find such corrections. therefore, our results suggest a possible way of detecting fundamental quantum effects in astronomical observations.
|
arxiv:1204.2015
|
we propose a new method to conserve the total energy to round - off error in grid - based codes for hydrodynamic simulations with self - gravity. a formula for the energy flux due to the work done by the the self - gravitational force is given, so the change in total energy can be written in conservative form. numerical experiments with the code athena show that the total energy is indeed conserved with our new algorithm and the new algorithm is second order accurate. we have performed a set of tests that show the numerical errors in the traditional, non - conservative algorithm can affect the dynamics of the system. the new algorithm only requires one extra solution of the poisson equation, as compared to the traditional algorithm which includes self - gravity as a source term. if the poisson solver takes a negligible fraction of the total simulation time, such as when ffts are used, the new algorithm is almost as efficient as the original method. this new algorithm is useful in eulerian hydrodynamic simulations with self - gravity, especially when results are sensitive to small energy errors, as for radiation pressure dominated flow.
|
arxiv:1208.1795
|
fermilab experiment 866 has performed an absolute measurement of continuum dimuon ( drell - yan ) cross sections in 800 - gev / c $ pp $ and $ pd $ interactions. results differential in the mass, feynman - $ x $ ( $ x _ f $ ) and transverse momenta ( $ p _ t $ ) of the dimuon pairs are reported. these results represent the most extensive study of the drell - yan process to date, based on a data sample of 175, 000 dimuon events covering the widest range in kinematics yet achieved ( $ 4. 2 \ leq m \ leq 16. 85 $ gev and $ - 0. 05 \ leq x _ f \ leq 0. 8 $ ) with this level of precision. the cross sections are primarily sensitive to the magnitude and shape of the light antiquark distributions ( $ \ bar { d } ( x ) $ and $ \ bar { u } ( x ) $ ) in the nucleon, but also provide important information on the valence quarks as well as the gluons. they are in good agreement with other existing proton - induced drell - yan experiments. there is also general agreement between the data and next - to - leading - order calculations based on various sets of parton distribution functions. differences between data and theory are examined, and the potential impact of these data on future parameterizations of the parton distributions are discussed.
|
arxiv:hep-ex/0301031
|
the paper is concerned with comparative analysis of differential and integral formulations for boundary value problems in nonlocal elasticity. for the sake of simplicity, the focus is on an antiplane problem for a half - space for an exponential kernel. first, a surface loading in the form of a travelling harmonic wave is studied. this provides a counter - example, revealing that within the framework of eringen ' s theory the solution to the differential model does not satisfy the equation of motion in nonlocal stresses underlying the related integral formulation. a more general differential setup, starting from singularly perturbed equations expressing the local stresses through the nonlocal ones, is then investigated. it is emphasized that the transformation of the original integral formulation to the differential one in question is only possible provided that two additional conditions on nonlocal stresses hold on the surface. as a result, the formulated problem subject to three boundary conditions appears to be ill - posed. next, the asymptotic solution of the singularly perturbed problem, subject to a prescribed stress on the boundary, together with only one of the aforementioned extra conditions, is obtained at a small internal size. three - term expansion is obtained, leading to a boundary value problem in local stresses over interior domain. the associated differential equations are identical to those proposed by eringen, however, the derived effective boundary condition incorporates the effect of a nonlocal boundary layer which has previously been ignored. moreover, the calculated nonlocal correction to the classical antiplane problem for an elastic half - space, coming from the boundary conditions is by order of magnitude greater than that appearing in the equations of motion. finally, it is shown that the proposed effective condition supports an antiplane surface wave.
|
arxiv:2107.09925
|
we present optical and near - infrared integral field spectroscopy of the scuba galaxy smm j163650. 43 + 405734. 5 ( elais n2 850. 4 ) at z = 2. 385. we combine ly - alpha and h - alpha emission line maps and velocity structure with high resolution hst acs and nicmos imaging to probe the complex dynamics of this vigorous star - burst galaxy. the imaging data shows a complex morphology, consisting of at least three components separated by ~ 1 ' ' ( 8kpc ) in projection. when combined with the h - alpha velocity field from ukirt uist ifu observations we identify two components whose redshifts are coincident with the systemic redshift, measured from previous co observations, one of which shows signs of agn activity. a third component is offset by 220 + / - 50km / s from the systemic velocity. the total star formation rate of the whole system ( estimated from the narrow - line h - alpha and uncorrected for reddening ) is 340 + / - 50mo / yr. the ly - alpha emission mapped by the gmos ifu covers the complete galaxy and is offset by + 270 + / - 40km / s from the systemic velocity. this velocity offset is comparable to that seen in rest - frame uv - selected galaxies at similar redshifts and usually interpreted as a star - burst driven wind. the extended structure of the ly - alpha emission suggests that this wind is not a nuclear phenomenon, but is instead a galactic scale outflow. our observations suggest that the vigorous activity in n2 850. 4 is arising as a result of an interaction between at least two dynamically - distinct components, resulting in a strong starburst, a starburst - driven wind and actively - fuelled agn activity. [ abridged ]
|
arxiv:astro-ph/0502096
|
as rdf becomes more widely established and the amount of linked data is rapidly increasing, the efficient querying of large amount of data becomes a significant challenge. in this paper, we propose a family of algorithms for querying large amount of linked data in a distributed manner. these query evaluation algorithms are independent of the way the data is stored, as well as of the particular implementation of the query evaluation. we then use the mapreduce paradigm to present a distributed implementation of these algorithms and experimentally evaluate them, although the algorithms could be straightforwardly translated into other distributed processing frameworks. we also investigate and propose multiple query decomposition approaches of basic graph patterns ( subclass of sparql queries ) that are used to improve the overall performance of the distributed query answering. a deep analysis of the effectiveness of these decomposition algorithms is also provided.
|
arxiv:2209.05359
|
in this study, we establish a unified framework to deal with the high dimensional matrix completion problem under flexible nonignorable missing mechanisms. although the matrix completion problem has attracted much attention over the years, there are very sparse works that consider the nonignorable missing mechanism. to address this problem, we derive a row - and column - wise matrix u - statistics type loss function, with the nuclear norm for regularization. a singular value proximal gradient algorithm is developed to solve the proposed optimization problem. we prove the non - asymptotic upper bound of the estimation error ' s frobenius norm and show the performance of our method through numerical simulations and real data analysis.
|
arxiv:2504.04016
|
we study a recent generalization proposed for the xy model in two and three dimensions. using both, the continuum limit and discrete lattice, we obtained the vortex configuration and shown that out - of - plane vortex solutions are deeply jeopardized whenever the parameter of generalization, $ l $, is increased. the critical temperature for such models is calculated using the self consistent harmonic approximation. in both, two - and three - dimensional cases, such a temperature decreases with raising $ l $. our results are also compared with other approximated methods available in the literature.
|
arxiv:cond-mat/0306682
|
dark matter remains a topic of ongoing controversy. it has gained attention in the theoretical description of compact objects such as neutron stars with cores of very dense matter. various candidates have been proposed for dark matter in the scientific literature. among them, the sexaquark has been identified as a potential bosonic particle capable of being formed in neutron star matter based on its mass characteristics. in this study, we investigate the viability of the sexaquark as a candidate for dark matter, particularly under certain density conditions. our goal is to address the challenges associated with the formation of a bosonic particle in a highly dense medium without compromising the stability of the neutron star. to achieve this, we introduce a straightforward linear mass shift for the sexaquark within the hadronic equation of state, utilizing a relativistic density functional approach. in our investigation, it is observed that the inclusion of sexaquark as a candidate for dark matter within the hadronic matter equation of state, although featuring a repulsive interaction with baryonic matter, softens the equation of state. we suppose that the strength of the interaction of dark matter with baryonic matter increases linearly with the baryon density. we observe that raising the effective mass of the sexaquark, as a result of increasing its vacuum mass, causes an increased stiffening of the equation of state as compared to the case of a constant mass. we determine the lower and upper mass boundaries for this bosonic dark matter based on observational constraints for neutron stars within the dd2y - t model when a phase transition to quark matter phase is employed.
|
arxiv:2402.18686
|
recent progress in artificial intelligence ( ai ) marks a pivotal moment in human history. it presents the opportunity for machines to learn, adapt, and perform tasks that have the potential to assist people, from everyday activities to their most creative and ambitious projects. it also has the potential to help businesses and organizations harness knowledge, increase productivity, innovate, transform, and power shared prosperity. this tremendous potential raises two fundamental questions : ( 1 ) will ai actually advance national and global economic transformation to benefit society at large? and ( 2 ) what issues must we get right to fully realize ai ' s economic value, expand prosperity and improve lives everywhere? we explore these questions by considering the recent history of technology and innovation as a guide for the likely impact of ai and what we must do to realize its economic potential to benefit society. while we do not presume the future will be entirely like that past, for reasons we will discuss, we do believe prior experience with technological change offers many useful lessons. we conclude that while progress in ai presents a historic opportunity to advance our economic prosperity and future wellbeing, its economic benefits will not come automatically and that ai risks exacerbating existing economic challenges unless we collectively and purposefully act to enable its potential and address its challenges. we suggest a collective policy agenda - involving developers, deployers and users of ai, infrastructure providers, policymakers, and those involved in workforce training - that may help both realize and harness ai ' s economic potential and address its risks to our shared prosperity.
|
arxiv:2401.09718
|
we present an experimental study of spin - torque driven vortex self - oscillations in magnetic nanocontacts. we find that above a certain threshold in applied currents, the vortex gyration around the nanocontact is modulated by relaxation oscillations, which involve periodic reversals of the vortex core. this modulation leads to the appearance of commensurate but also more interestingly here, incommensurate states, which are characterized by devil ' s staircases in the modulation frequency. we use frequency - and time - domain measurements together with advanced time - series analyses to provide experimental evidence of chaos in incommensurate states of vortex oscillations, in agreement with theoretical predictions.
|
arxiv:1903.00921
|
we derive the formulae of fluctuating hydrodynamics appropiate to a relativistically consistent divergence type theory, obtaining landau - lifshitz fluctuating hydrodynamics as a limiting case.
|
arxiv:gr-qc/9708048
|
following the work of harris and kudla we prove a more general form of a conjecture of jacquet relating the non - vanishing of a certain period integral to non - vanishing of the central critical value of a certain $ l $ - function. as a consequence we deduce certain local results about the existence of $ gl _ 2 ( k ) $ - invariant linear forms on irreducible, admissible representations of $ gl _ 2 ( { \ bbb k } ) $ for $ { \ bbb k } $ a commutative semi - simple cubic algebra over a non - archimedean local field $ k $ in terms of certain local epsilon factors which were proved only in certain cases by the first author in his earlier work. this has been achieved by globalising a locally distinguished representation to a globally distinguished representation, a result of independent interest.
|
arxiv:math/0606515
|
rxte, ginga, and osse observations have revealed an intense low - energy gamma - ray continuum emission from the galactic plane, which is commonly interpreted as evidence for the possible existence of a strong flux of low - energy cosmic ray electrons. in this paper i discuss the scenario of a hadronic origin of the soft galactic gamma - ray continuum through inverse bremsstrahlung. a flux of low - energy cosmic rays strong enough to produce the observed spectrum of gamma - rays implies substantial gamma - ray emission at a few mev through nuclear de - excitation. it is shown that the existing limits on excess 3 - 7 mev emission from the galactic plane, in concert with the constraints from pion - decay gamma - ray emission at higher energies, are in serious conflict with an inverse bremsstrahlung origin of the galactic soft gamma - ray emission for any physically plausible low - energy cosmic ray spectrum. while in case of energetic heavy nuclei the limits are violated by about an order of magnitude, for a large population of low - energy protons the implied gamma - ray line flux and pion - decay continuum intensity are larger than the existing limits by at least a factor of 2.
|
arxiv:astro-ph/9809052
|
we consider a two - level quantum system ( qubit ) which is continuously measured by a detector and calculate the spectral density of the detector output. in the weakly coupled case the spectrum exhibits a moderate peak at the frequency of quantum oscillations and a lorentzian - shape increase of the detector noise at low frequency. with increasing coupling the spectrum transforms into a single lorentzian corresponding to random jumps between two states. we prove that the bayesian formalism for the selective evolution of the density matrix gives the same spectrum as the conventional master equation approach, despite the significant difference in interpretation. the effects of the detector nonideality and the finite - temperature environment are also discussed.
|
arxiv:cond-mat/0003225
|
we investigate a sequence of quadratic topological terms of the chern - simons type in different spacetime dimensions, related by dimensional compactification and sharing the properties of topological mass generation and statistical transmutation. the implications for bosonization in several dimensions are also analyzed.
|
arxiv:hep-th/0107109
|
axions, hypothetical particles theorized to solve the strong cp - problem, are presently being considered as strong candidates as cold dark matter constituents. the signal power of resonant - based axion detectors, known as haloscopes, is directly proportional to their quality factor $ q $. in this paper, the impact of the use of superconductors in the performances of the haloscopes is studied by evaluating the obtainable $ q $. in particular, the surface resistance $ r _ s $ of nbti, nb $ _ 3 $ sn, yba $ _ 2 $ cu $ _ 3 $ o $ _ { 7 - \ delta } $ and fese $ _ { 0. 5 } $ te $ _ { 0. 5 } $ is computed in the frequency, magnetic field and temperature ranges of interest, starting from the measured vortex motion complex resistivity and screening lengths of these materials. from $ r _ s $ the quality factor $ q $ of a cylindrical haloscope with copper conical bases and superconductive lateral wall, operating with the tm $ _ { 010 } $ mode, is evaluated and used to perform a comparison of the performances of the different materials. both yba $ _ 2 $ cu $ _ 3 $ o $ _ { 7 - \ delta } $ and fese $ _ { 0. 5 } $ te $ _ { 0. 5 } $ are shown to improve the measurement sensitivity by almost an order of magnitude with respect to a whole cu cavity, while nbti is shown to be suitable only at lower frequencies ( < 10 ghz ). nb $ _ 3 $ sn can give an intermediate improvement in the whole spectrum of interest.
|
arxiv:2112.12775
|
guided by the internal - reference rule and the known band offsets in iii - v and ii - vi diluted magnetic semiconductors, we discuss the feasibility of obtaining p - type conductivity, required for the carrier - induced ferromagnetism, as well as the cases for which the doping by shallow impurities may lead to the ferromagnetism driven by the double exchange. we consider the dependence of kinetic exchange on the p - d hybridization, on the electronic configurations of the magnetic ions, and on the energies of the charge transfer between the valence band of host materials and the magnetic ions. in the case of mn - based ii - vi compounds, the doping by acceptors is necessary for the hole - induced ferromagnetism. the latter is, however, possible without any doping for some of mn -, fe - or co - based iii - v magnetic semiconductors. in nitrides with fe or co carrier - induced ferromagnetism with t _ c > 300k is expected in the presence of acceptor doping.
|
arxiv:cond-mat/0201012
|
security becomes an extremely important issue in smart grid. to maintain the steady operation for smart power grid, massive measurement devices must be allocated widely among the power grid. previous studies are focused on false data injection attack to the smart grid system. in practice, false data injection attack is not easy to implement, since it is not easy to hack the power grid data communication system. in this paper, we demonstrate that a novel time stamp attack is a practical and dangerous attack scheme for smart grid. since most of measurement devices are equipped with global positioning system ( gps ) to provide the time information of measurements, it is highly probable to attack the measurement system by spoofing the gps. by employing the real measurement data in north american power grid, simulation results demonstrate the effectiveness of the time stamp attack on smart grid.
|
arxiv:1102.1408
|
we present a driven dissipative protocol for creating an optical analog of the laughlin state in a system of rydberg polaritons in a twisted optical cavity. we envision resonantly driving the system into a 4 - polariton state by injecting photons in carefully selected modes. the dissipative nature of the polariton - polariton interactions leads to a decay into a two - polariton analog of the laughlin state. generalizations of this technique could be used to explore fractional statistics and anyon based quantum information processing. we also model recent experiments that attempt to coherently drive into this same state.
|
arxiv:2107.06346
|
code retrieval techniques and tools have been playing a key role in facilitating software developers to retrieve existing code fragments from available open - source repositories given a user query. despite the existing efforts in improving the effectiveness of code retrieval, there are still two main issues hindering them from being used to accurately retrieve satisfiable code fragments from large - scale repositories when answering complicated queries. first, the existing approaches only consider shallow features of source code such as method names and code tokens, but ignoring structured features such as abstract syntax trees ( asts ) and control - flow graphs ( cfgs ) of source code, which contains rich and well - defined semantics of source code. second, although the deep learning - based approach performs well on the representation of source code, it lacks the explainability, making it hard to interpret the retrieval results and almost impossible to understand which features of source code contribute more to the final results. to tackle the two aforementioned issues, this paper proposes mman, a novel multi - modal attention network for semantic source code retrieval. a comprehensive multi - modal representation is developed for representing unstructured and structured features of source code, with one lstm for the sequential tokens of code, a tree - lstm for the ast of code and a ggnn ( gated graph neural network ) for the cfg of code. furthermore, a multi - modal attention fusion layer is applied to assign weights to different parts of each modality of source code and then integrate them into a single hybrid representation. comprehensive experiments and analysis on a large - scale real - world dataset show that our proposed model can accurately retrieve code snippets and outperforms the state - of - the - art methods.
|
arxiv:1909.13516
|
the main motivation for this work was to find an explicit formula for a " szego - regularized " determinant of a zeroth order pseudodifferential operator ( psdo ) on a zoll manifold. the idea of the szego - regularization was suggested by v. guillemin and k. okikiolu. they have computed the second term in a szego type expansion on a zoll manifold of an arbitrary dimension. in the present work we compute the third asymptotic term in any dimension. in the case of dimension 2, our formula gives the above mentioned expression for the szego - redularized determinant of a zeroth order psdo. the proof uses a new combinatorial identity, which generalizes a formula due to g. a. hunt and f. j. dyson. this identity is related to the distribution of the maximum of a random walk with i. i. d. steps on the real line. the full version of this paper is also available, math. fa / 0212275.
|
arxiv:math/0212273
|
the distribution is calculated of the electron spin polarization under current - driven spin injection from a probe to a ferromagnetic film. it is shown that the main parameters determining difference of the spin polarization from the equilibrium value are the current density and the spin polarization of the probe material, while the relation between the probe diameter and the spin diffusion length influences the result very weakly, to a certain extent. a possibility is shown of reaching inverse population of the spin subbands at distances from the probe boundary comparable with the spin diffusion length.
|
arxiv:0912.2602
|
temporal order in living matters reflects the self - organizing nature of dynamical processes driven out of thermodynamic equilibrium. because of functional reason, the period of a biochemical oscillation must be tuned to a specific value with precision ; however, according to the thermodynamic uncertainty relation ( tur ), the precision of oscillatory period is constrained by the thermodynamic cost of generating it. after reviewing the basics of chemical oscillations using brusselator as a model system, we study the glycolytic oscillation generated by octameric phosphofructokinase ( pfk ), which is known to display a period of several minutes. by exploring the phase space of glycolytic oscillations, we find that the glycolytic oscillation under the cellular condition is realized in a cost effective manner. specifically, over the biologically relevant range of parameter values of glycolysis and octameric pfk, the entropy production from the glycolytic oscillation is minimal when the oscillation period is ( 5 - 10 ) minutes. further, the glycolytic oscillation is found at work near the phase boundary of limit cycles, suggesting that a moderate increase of glucose injection rate leads to the loss of oscillatory dynamics, which is reminiscent of the loss of pulsatile insulin release resulting from elevated blood glucose level.
|
arxiv:2102.06748
|
general classes of bivariate distributions are well studied in literature. most of these classes are proposed via a copula formulation or extensions of some characterisation properties in the univariate case. in kundu ( 2022 ) we see one such semi - parametric family useful to model bivariate data with ties. this model is a general semi - parametric model with a baseline. in this paper we present a characterisation property of this class of distributions in terms of a functional equation. the general solution to this equation is explored. necessary and sufficient conditions under which the solution becomes a bivariate distribution is investigated.
|
arxiv:2212.13385
|
in this letter, we propose how to measure the quantized nonlinear transport using two - dimensional ultracold atomic fermi gases in a harmonic trap. this scheme requires successively applying two optical pulses in the left and lower half - planes and then measuring the number of extra atoms in the first quadrant. in ideal situations, this nonlinear density response to two successive pulses is quantized, and the quantization value probes the euler characteristic of the local fermi sea at the trap center. we investigate the practical effects in experiments, including finite pulse duration, finite edge width of pulses, and finite temperature, which can lead to deviation from quantization. we propose a method to reduce the deviation by averaging measurements performed at the first and third quadrants, inspired by symmetry considerations. with this method, the quantized nonlinear response can be observed reasonably well with experimental conditions readily achieved with ultracold atoms.
|
arxiv:2206.09845
|
the five - hundred - meter aperture spherical radio telescope ( fast ), the largest single dish radio telescope in the world, has implemented an innovative technology for its huge reflector, which changes the shape of the primary reflector from spherical to that of a paraboloid of 300 m aperture. here we explore how the current fast sensitivity can potentially be further improved by increasing the illuminated area ( i. e., the aperture of the paraboloid embedded in the spherical surface ). alternatively, the maximum zenith angle can be increased to give greater sky coverage by decreasing the illuminated aperture. different parabolic apertures within the fast capability are analyzed in terms of how far the spherical surface would have to move to approximate a paraboloid. the sensitivity of fast can be improved by approximately 10 % if the aperture of the paraboloid is increased from 300 m to 315 m. the parabolic aperture lies within the main spherical surface and does not extend beyond its edge. the maximum zenith angle can be increased to approximately 35 degrees from 26. 4 degrees, if we decrease the aperture of the paraboloid to 220 m. this would still give a sensitivity similar to the arecibo 305 m radio telescope. radial deviations between paraboloids of different apertures and the spherical surfaces of differing radii are also investigated. maximum zenith angles corresponding to different apertures of the paraboloid are further derived. a spherical surface with a different radius can provide a reference baseline for shape - changing applied through active reflector technology to fast - like telescopes.
|
arxiv:2012.11167
|
we consider the problem of jointly recovering the vector $ \ boldsymbol { b } $ and the matrix $ \ boldsymbol { c } $ from noisy measurements $ \ boldsymbol { y } = \ boldsymbol { a } ( \ boldsymbol { b } ) \ boldsymbol { c } + \ boldsymbol { w } $, where $ \ boldsymbol { a } ( \ cdot ) $ is a known affine linear function of $ \ boldsymbol { b } $ ( i. e., $ \ boldsymbol { a } ( \ boldsymbol { b } ) = \ boldsymbol { a } _ 0 + \ sum _ { i = 1 } ^ q b _ i \ boldsymbol { a } _ i $ with known matrices $ \ boldsymbol { a } _ i $ ). this problem has applications in matrix completion, robust pca, dictionary learning, self - calibration, blind deconvolution, joint - channel / symbol estimation, compressive sensing with matrix uncertainty, and many other tasks. to solve this bilinear recovery problem, we propose the bilinear adaptive vector approximate message passing ( bad - vamp ) algorithm. we demonstrate numerically that the proposed approach is competitive with other state - of - the - art approaches to bilinear recovery, including lifted vamp and bilinear gamp.
|
arxiv:1809.00024
|
we have examined the physics and the experimental feasibility at the ags of various kaon decay processes in which the polarization of a muon in the final state is measured. valuable information on cp violation, the ckm matrix or new physics can be obtained with these measurements and therefore they are well motivated. in particular, models of non - standard cp violation that produce the baryon asymmetry of the universe could also produce effects observable in these measurements. limits from measurements such as the neutron and electron electric dipole moment, and epsilon - prime over epsilon in neutral kaon decays do not eliminate all of these models. we have made a more detailed examination of the measurement of the out of the plane muon polarization in kmu3 decays. with our current knowledge of the ags kaon beams and detector techniques it is possible to measure this polarization with an error approaching 10 * * - 4. such an experiment would be well justified since the sensitivity is well beyond the current direct experimental limit ( 5. 3 times 10 * * - 3 ) and the projected sensitivity ( 10 * * - 3 ) of the currently running experiment at kek in japan.
|
arxiv:hep-ex/9608015
|
we determine the set of primitive integral solutions to the generalised fermat equation x ^ 2 + y ^ 3 = z ^ 15. as expected, the only solutions are the trivial ones with xyz = 0 and the non - trivial pair ( x, y, z ) = ( + - 3, - 2, 1 ).
|
arxiv:1309.4421
|
the aim of the papers is to describe the left regular left quotient ring $ { } ' q ( r ) $ and the right regular right quotient ring $ q ' ( r ) $ for the following algebras $ r $ : $ \ ms _ n = \ ms _ 1 ^ { \ t n } $ is the algebra of one - sided inverses, where $ \ ms _ 1 = k \ langle x, y \, | \, yx = 1 \ rangle $, $ \ ci _ n = k \ langle \ der _ 1, \ ldots, \ der _ n, \ int _ 1, \ ldots, \ int _ n \ rangle $ is the algebra of scalar integro - differential operators and the jacobian algebra $ \ ma _ 1 = k \ langle x, \ der, ( \ der x ) ^ { - 1 } \ rangle $. the sets of left and right regular elements of the algebras $ \ ms _ 1 $, $ \ ci _ 1 $, $ \ ma _ 1 $ and $ \ mi _ 1 = k \ langle x, \ der, \ int \ rangle $. a progress is made on the following conjecture, \ cite { clas - lreg - quot } : $ $ { } ' q ( \ mi _ n ) \ simeq q ( a _ n ) \ ; \ ; { \ rm where } \ ; \ ; \ mi _ n = k \ bigg \ langle x _ 1, \ ldots, x _ n, \ der _ 1, \ ldots, \ der _ n, \ int _ 1, \ ldots, \ int _ n \ bigg \ rangle $ $ is the algebra of polynomial integro - differential operators and $ q ( a _ n ) $ is the classical quotient ring ( of fractions ) of the $ n $ ' th weyl algebra $ a _ n $, i. e. a criterion is given when the isomorphism holds. we produce several general constructions of left ore and left denominator sets that appear naturally in applications and are of independent interest and use them to produce explicit left denominator sets that give the localization ring isomorphic to $ { } ' q ( \ ms _ n ) $ or $ { } ' q ( \ mi _ n ) $ or $ { } ' q ( \ ma _ n ) $ where $ \
|
arxiv:2404.12116
|
we prove the existence of global, smooth solutions to the 2d muskat problem in the stable regime whenever the product of the maximal and minimal slopes is strictly less than 1. the curvature of these solutions solutions decays to 0 as $ t $ goes to infinity, and they are unique when the initial data is $ c ^ { 1, \ epsilon } $. we do this by constructing a modulus of continuity generated by the equation, just as kiselev, nazarov, and volberg did in their proof of the global well - posedness for the quasi - geostraphic equation.
|
arxiv:1704.08401
|
learning depth and camera ego - motion from raw unlabeled rgb video streams is seeing exciting progress through self - supervision from strong geometric cues. to leverage not only appearance but also scene geometry, we propose a novel self - supervised two - stream network using rgb and inferred depth information for accurate visual odometry. in addition, we introduce a sparsity - inducing data augmentation policy for ego - motion learning that effectively regularizes the pose network to enable stronger generalization performance. as a result, we show that our proposed two - stream pose network achieves state - of - the - art results among learning - based methods on the kitti odometry benchmark, and is especially suited for self - supervision at scale. our experiments on a large - scale urban driving dataset of 1 million frames indicate that the performance of our proposed architecture does indeed scale progressively with more data.
|
arxiv:1910.01764
|
high - energy neutrinos from astrophysical transients serve as a probe of neutrino physics beyond the standard model. in particular, nonstandard interaction of neutrinos with the cosmic neutrino background or dark matter ( dm ) may have imprints on not only their spectra but also the arrival and time - delay distributions. assuming that the interaction occurs at most once during the neutrino propagation, we provide general analytic formulas for light curves of the neutrino echoes induced by bsm. the formulas can be used for constraining neutrino - neutrino scattering, neutrino - dm scattering, and other scattering processes experienced by relativistic particles.
|
arxiv:2204.08924
|
shear - banding is a curious but ubiquitous phenomenon occurring in soft matter. the phenomenological similarities between the shear - banding transition and phase transitions has pushed some researchers to adopt a ' thermodynamical ' approach, in opposition to the more classical ' mechanical ' approach to fluid flows. in this heuristic review, we describe why the apparent dichotomy between those approaches has slowly faded away over the years. to support our discussion, we give an overview of different interpretations of a single equation, the diffusive johnson - segalman ( djs ) equation, in the context of shear - banding. we restrict ourselves to djs, but we show that the equation can be written in various equivalent forms usually associated with opposite approaches. we first review briefly the origin of the djs model and its initial rheological interpretation in the context of shear - banding. then we describe the analogy between djs and reaction - diffusion equations. in the case of anisotropic diffusion, we show how the djs governing equations for steady shear flow are analogous to the equations of the dynamics of a particle in a quartic potential. going beyond the existing literature, we then draw on the lagrangian formalism to describe how the boundary conditions can have a key impact on the banding state. finally, we reinterpret the djs equation again and we show that a rigorous effective free energy can be constructed, in the spirit of early thermodynamic interpretations or in terms of more recent approaches exploiting the language of irreversible thermodynamics.
|
arxiv:1107.1247
|
quality estimation ( qe ), the evaluation of machine translation output without the need of explicit references, has seen big improvements in the last years with the use of neural metrics. in this paper we analyze the viability of using qe metrics for filtering out bad quality sentence pairs in the training data of neural machine translation systems ~ ( nmt ). while most corpus filtering methods are focused on detecting noisy examples in collections of texts, usually huge amounts of web crawled data, qe models are trained to discriminate more fine - grained quality differences. we show that by selecting the highest quality sentence pairs in the training data, we can improve translation quality while reducing the training size by half. we also provide a detailed analysis of the filtering results, which highlights the differences between both approaches.
|
arxiv:2311.05350
|
we present a study of the host galaxy of the gamma - ray burst ( grb ) of may 5 2006 ( grb 060505 ). the host is spatially resolved in both imaging data and in a long slit spectrum including the grb site. we find the galaxy to be a sbc spiral, which is unusual for a long grb host galaxy. the site of the grb is considerably different from the rest of the galaxy with intense star formation, low metallicity and a young age. this suggest a massive stellar progenitor rather than a merger of compact objects which has been suggested based on the the relatively short duration of t _ 90 = 4s for the prompt emission.
|
arxiv:0706.0674
|
we give more evidence for patterson ' s conjecture on sums of exponential sums, by getting an asymptotic for a sum of quartic exponential sums over $ \ q [ i ]. $ previously, the strongest evidence of patterson ' s conjecture over a number field is the paper of livn \ ' { e } and patterson \ cite { lp } on sums of cubic exponential sums over $ \ q [ \ omega ], \ omega ^ 3 = 1. $ the key ideas in getting such an asymptotic are a kuznetsov - like trace formula for metaplectic forms over a quartic cover of $ gl _ 2, $ and an identity on exponential sums relating kloosterman sums and quartic exponential sums. to synthesize the spectral theory and the exponential sum identity, there is need for a good amount of analytic number theory. an unexpected aspect of the asymptotic of the sums of exponential sums is that there can be a secondary main term additional to the main term which is not predicted in patterson ' s original paper \ cite { p }.
|
arxiv:1305.1243
|
active galactic nuclei ( agn ) is one of the main drivers for transition from star - forming disk to passive spheroidal galaxies. however, the role of large - scale environment versus one - on - one interactions in triggering different types of agn is still uncertain. we present a statistical study of the prevalence of the nuclear activity in isolated galaxies and physically bound isolated pairs. for the purpose of this study we considered optically and radio selected nuclear activity types. we aim to assess the effect of one - on - one interaction on the fraction of agn and the role of their large - scale environment. to study the effect of one - on - one interaction on the fraction of agn in isolated galaxy pairs, we compare with a sample of isolated galaxies homogeneously selected under the same isolation criterion. we examine the effect of the large - scale environment by comparing with control samples of single galaxies and galaxy pairs. in general we found no difference in the prevalence of optical agn for the considered samples. for massive galaxies, the fraction of optical agn in isolated galaxies is slightly higher than that in control samples. also the fraction of passives in high mass isolated galaxies is smaller than in any other sample. generally, there is no dependence on optical nuclear activity with local environment. on the other hand, we found evidence that radio agn are strongly affected by the local environment. optical agn phenomenon is related to cold gas accretion, while radio agn is related to hot gas accretion. in this context, there is more cold gas, fueling the central optical agn, in isolated systems. our results are in agreement with a scenario where cold gas accretion by secular evolution is the main driver of optical agn, while hot gas accretion and one - on - one interactions are the main drivers of radio agn activity.
|
arxiv:1605.05642
|
people deeply care about how fairly they are treated by robots. the established paradigm for probing fairness in human - robot interaction ( hri ) involves measuring the perception of the fairness of a robot at the conclusion of an interaction. however, such an approach is limited as interactions vary over time, potentially causing changes in fairness perceptions as well. to validate this idea, we conducted a 2x2 user study with a mixed design ( n = 40 ) where we investigated two factors : the timing of unfair robot actions ( early or late in an interaction ) and the beneficiary of those actions ( either another robot or the participant ). our results show that fairness judgments are not static. they can shift based on the timing of unfair robot actions. further, we explored using perceptions of three key factors ( reduced welfare, conduct, and moral transgression ) proposed by a fairness theory from organizational justice to predict momentary perceptions of fairness in our study. interestingly, we found that the reduced welfare and moral transgression factors were better predictors than all factors together. our findings reinforce the idea that unfair robot behavior can shape perceptions of group dynamics and trust towards a robot and pave the path to future research directions on moment - to - moment fairness perceptions
|
arxiv:2409.07560
|
this paper presents new constructions of models of hume ' s principle and basic law v with restricted amounts of comprehension. the techniques used in these constructions are drawn from hyperarithmetic theory and the model theory of fields, and formalizing these techniques within various subsystems of second - order peano arithmetic allows one to put upper and lower bounds on the interpretability strength of these theories and hence to compare these theories to the canonical subsystems of second - order arithmetic. the main results of this paper are : ( i ) there is a consistent extension of the hyperarithmetic fragment of basic law v which interprets the hyperarithmetic fragment of second - order peano arithmetic, and ( ii ) the hyperarithmetic fragment of hume ' s principle does not interpret the hyperarithmetic fragment of second - order peano arithmetic, so that in this specific sense there is no predicative version of frege ' s theorem.
|
arxiv:1407.0436
|
we will study the formation history of the milky way, and the earliest phases of its chemical enrichment, with a sample of more than 1. 5 million stars at high galactic latitude. elemental abundances of up to 20 elements with a precision of better than 0. 2 dex will be derived for these stars. the sample will include members of kinematically coherent substructures, which we will associate with their possible birthplaces by means of their abundance signatures and kinematics, allowing us to test models of galaxy formation. our target catalogue is also expected to contain 30, 000 stars at a metallicity of less than one hundredth that of the sun. this sample will therefore be almost a factor of 100 larger than currently existing samples of metal - poor stars for which precise elemental abundances are available ( determined from high - resolution spectroscopy ), enabling us to study the early chemical evolution of the milky way in unprecedented detail.
|
arxiv:1903.02468
|
we consider the action of a subtorus of the big torus on a toric variety. the aim of the paper is to define a natural notion of a quotient for this setting and to give an explicit algorithm for the construction of this quotient from the combinatorial data corresponding to the pair consisting of the subtorus and the toric variety. moreover, we study the relations of such quotients with good quotients. we construct a good model, i. e. a dominant toric morphism from the given toric variety to some ` ` maximal ' ' toric variety having a good quotient by the induced action of the given subtorus.
|
arxiv:math/9806049
|
in engineering and systems theory, redundancy is the intentional duplication of critical components or functions of a system with the goal of increasing reliability of the system, usually in the form of a backup or fail - safe, or to improve actual system performance, such as in the case of gnss receivers, or multi - threaded computer processing. in many safety - critical systems, such as fly - by - wire and hydraulic systems in aircraft, some parts of the control system may be triplicated, which is formally termed triple modular redundancy ( tmr ). an error in one component may then be out - voted by the other two. in a triply redundant system, the system has three sub components, all three of which must fail before the system fails. since each one rarely fails, and the sub components are designed to preclude common failure modes ( which can then be modelled as independent failure ), the probability of all three failing is calculated to be extraordinarily small ; it is often outweighed by other risk factors, such as human error. electrical surges arising from lightning strikes are an example of a failure mode which is difficult to fully isolate, unless the components are powered from independent power busses and have no direct electrical pathway in their interconnect ( communication by some means is required for voting ). redundancy may also be known by the terms " majority voting systems " or " voting logic ". redundancy sometimes produces less, instead of greater reliability – it creates a more complex system which is prone to various issues, it may lead to human neglect of duty, and may lead to higher production demands which by overstressing the system may make it less safe. redundancy is one form of robustness as practiced in computer science. geographic redundancy has become important in the data center industry, to safeguard data against natural disasters and political instability ( see below ). = = forms of redundancy = = in computer science, there are four major forms of redundancy : hardware redundancy, such as dual modular redundancy and triple modular redundancy information redundancy, such as error detection and correction methods time redundancy, performing the same operation multiple times such as multiple executions of a program or multiple copies of data transmitted software redundancy such as n - version programming a modified form of software redundancy, applied to hardware may be : distinct functional redundancy, such as both mechanical and hydraulic braking in a car. applied in the
|
https://en.wikipedia.org/wiki/Redundancy_(engineering)
|
the functional renormalisation group ( frg ) has evolved into a versatile tool in condensed matter theory for studying important aspects of correlated electron systems. practical applications of the method often involve a high numerical effort, motivating the question in how far high performance computing ( hpc ) can leverage the approach. in this work we report on a multi - level parallelisation of the underlying computational machinery and show that this can speed up the code by several orders of magnitude. this in turn can extend the applicability of the method to otherwise inaccessible cases. we exploit three levels of parallelisation : distributed computing by means of message passing ( mpi ), shared - memory computing using openmp, and vectorisation by means of simd units ( single - instruction - multiple - data ). results are provided for two distinct high performance computing ( hpc ) platforms, namely the ibm - based bluegene / q system juqueen and an intel sandy - bridge - based development cluster. we discuss how certain issues and obstacles were overcome in the course of adapting the code. most importantly, we conclude that this vast improvement can actually be accomplished by introducing only moderate changes to the code, such that this strategy may serve as a guideline for other researcher to likewise improve the efficiency of their codes.
|
arxiv:1510.07799
|
we have considered the existence of neutron star magnetic field given by the cyclotron lines. we collected the data of 9 sources of high - mass x - ray binaries with supergiant companions as a case of testing our model, to demonstrate their distribution and evolution. the wind velocity, spin period and magnetic field strength are studied under different mass loss rate. in our model, correlations between mass - loss rate and wind velocity are found and can be tested in further observations. we examined the parameter space where wind accretion is allowed, avoiding barrier of rotating magnetic fields, with robust data of magnetic field of neutron stars. our model shows that most of sources ( 6 of 9 systems ) can be fed by the wind with relatively slow velocity, and this result is consistent with previous predictions. in a few sources, our model cannot fit under the standard wind accretion scenario. in these peculiar cases, other scenarios ( disk formation, partial roche lobe overflow ) should be considered. this would provide information about the evolutionary tracks of various types of binaries, and thus show a clear dichotomy behavior in wind - fed x - ray binary systems.
|
arxiv:1809.01213
|
in this paper we deal with the signed roman domination and signed total roman domination problems. for each problem we propose two integer linear programming ( ilp ) formulations, the constraint programming ( cp ) formulation and variable neighborhood search ( vns ) method. we present proofs for the correctness of the ilp formulations and a polyhedral study in which we show that the polyhedrons of the two model relaxations are equivalent. vns uses specifically designed penalty function that allows the appearance of slightly infeasible solutions. the acceptance of these solutions directs the overall search process to the promising areas in the long run. all proposed approaches are tested on the large number of instances. experimental results indicate that all of them reach optimal solutions for the most of small and middle scale instances. both ilp models have proven to be more successful than the other two methods.
|
arxiv:2201.00394
|
the quantum machine learning model is emerging as a new model that merges quantum computing and machine learning. simulating very deep quantum machine learning models requires a lot of resources, increasing exponentially based on the number of qubits and polynomially based on the depth value. almost all related works use state - vector - based simulators due to their parallelization and scalability. extended stabilizer formalism simulators solve the same problem with fewer computations because they act on stabilizers rather than long vectors. however, the gate application sequential property leads to less popularity and poor performance. in this work, we parallelize the process, making it feasible to deploy on multi - core devices. the results show that the proposal implementation on python is faster than qiskit, the current fastest simulator, 4. 23 times in the case of 4 - qubits, 60, 2k gates.
|
arxiv:2502.10685
|
we study the semi - random graph process, and a variant process recently suggested by nick wormald. we show that these two processes are asymptotically equally fast in constructing a semi - random graph $ g $ that has property $ { \ mathcal p } $, for the following examples of $ { \ mathcal p } $ : - $ { \ mathcal p } $ is the set of graphs containing a $ d $ - degenerate subgraph, where $ d \ ge 1 $ is fixed ; - $ { \ mathcal p } $ is the set of $ k $ - connected graphs, where $ k \ ge 1 $ is fixed. in particular, our result of the $ k $ - connectedness above settles the open case $ k = 2 $ of the original semi - random graph process. we also prove that there exist properties $ { \ mathcal p } $ where the two semi - random graph processes do not construct a graph in $ { \ mathcal p } $ asymptotically equally fast. we further propose some conjectures on $ { \ mathcal p } $ for which the two processes perform differently.
|
arxiv:2309.05881
|
we introduce an iterative spectral disentangling technique combined with doppler imaging in order to recover surface temperature maps for both components of double - lined active binary systems. our method provides an opportunity to separate spectra of the active components while minimizing the unwanted disturbances on the given line profile from the other component. the efficiency of the method is demonstrated on real data of the double - lined rs cvn - type binary v824 ara. the resulting doppler images reveal cool spots on the polar regions as well as low - latitude features on both of the stars. moreover, both components have hot spots, that are facing each other. this may indicate interconnection between the stellar magnetic fields.
|
arxiv:1310.4020
|
we define, for an arbitrary partially ordered set, a multi - variable polynomial generalizing the hook polynomial.
|
arxiv:1412.7666
|
although conceptualization has been widely studied in semantics and knowledge representation, it is still challenging to find the most accurate concept phrases to characterize the main idea of a text snippet on the fast - growing social media. this is partly attributed to the fact that most knowledge bases contain general terms of the world, such as trees and cars, which do not have the defining power or are not interesting enough to social media app users. another reason is that the intricacy of natural language allows the use of tense, negation and grammar to change the logic or emphasis of language, thus conveying completely different meanings. in this paper, we present tag, a high - quality concept matching dataset consisting of 10, 000 labeled pairs of fine - grained concepts and web - styled natural language sentences, mined from the open - domain social media. the concepts we consider represent the trending interests of online users. associated with tag is a concept graph of these fine - grained concepts and entities to provide the structural context information. we evaluate a wide range of popular neural text matching models as well as pre - trained language models on tag, and point out their insufficiency to tag social media content with the most appropriate concept. we further propose a novel graph - graph matching method that demonstrates superior abstraction and generalization performance by better utilizing both the structural context in the concept graph and logic interactions between semantic units in the sentence via syntactic dependency parsing. we open - source both the tag dataset and the proposed methods to facilitate further research.
|
arxiv:2110.06892
|
the latest generation of transistors are nanoscale devices whose performance and reliability are limited by thermal noise in low - power applications. therefore developing efficient methods to compute the voltage and current fluctuations in such non - linear electronic circuits is essential. traditional approaches commonly rely on adding gaussian white noise to the macroscopic dynamical circuit laws, but do not capture rare fluctuations and lead to thermodynamic inconsistencies. a correct and thermodynamically consistent approach can be achieved by describing single - electron transfers as poisson jump processes accounting for charging effects. but such descriptions can be computationally demanding. to address this issue, we consider the macroscopic limit which corresponds to scaling up the physical dimensions of the transistor and resulting in an increase of the number of electrons on the conductors. in this limit, the thermal fluctuations satisfy a large deviations principle which we show is also remarkably precise in settings involving only a few tens of electrons, by comparing our results with gillespie simulations and spectral methods. traditional approaches are recovered by resorting to an ad hoc diffusive approximation introducing inconsistencies. to illustrate these findings, we consider a low - power cmos inverter, or not gate, which is a basic primitive in electronic design. voltage ( resp. current ) fluctuations are obtained analytically ( semi - analytically ) and reveal interesting features.
|
arxiv:2205.12659
|
the negative symmetry flows are incorporated into the riemann - hilbert problem for the homogeneous $ a _ m $ - hierarchy and its $ \ hat { gl } ( m + 1, c ) $ extension. a loop group automorphism of order two is used to define a sub - hierarchy of $ \ hat { gl } ( m + 1, c ) $ hierarchy containing only the odd symmetry flows. the positive and negative flows of the $ \ pm 1 $ grade coincide with equations of the multidimensional toda model and of topological - anti - topological fusion.
|
arxiv:hep-th/0107056
|
a theoretical model of c - axis transport properties in cuprates is proposed. inter - plane and in - plane charge fluctuations make hopping between planes incoherent and diffusive ( the in - plane momentum is not conserved after tunneling ). the non - drude optical conductivity $ \ sigma _ c ( \ omega ) $ and the power - law temperature dependence of the { \ it dc } conductivity are generically explained by the strong fluctuations excited in the process of tunneling. several microscopic models of the charge fluctuation spectrum are considered.
|
arxiv:cond-mat/0005329
|
we consider incomplete observations of stochastic processes governing the spread of infectious diseases through finite populations by way of contact. we propose a flexible semiparametric modeling framework with at least three advantages. first, it enables researchers to study the structure of a population contact network and its impact on the spread of infectious diseases. second, it can accommodate short - and long - tailed degree distributions and detect potential superspreaders, who represent an important public health concern. third, it addresses the important issue of incomplete data. starting from first principles, we show when the incomplete - data generating process is ignorable for the purpose of bayesian inference for the parameters of the population model. we demonstrate the semiparametric modeling framework by simulations and an application to the partially observed mers epidemic in south korea in 2015. we conclude with an extended discussion of open questions and directions for future research.
|
arxiv:2107.00375
|
non - relativistic potential models are considered of the pure power v ( r ) = sgn ( q ) r ^ q and logarithmic v ( r ) = ln ( r ) types. envelope representations and kinetic potentials are employed to show that these potentials are actually in a single family. the log spectra can be obtained from the power spectra by the limit q - - > 0 taken in a smooth representation p _ { n \ ell } ( q ) for the eigenvalues e _ { n \ ell } ( q ). a simple approximation formula is developed which yields the first thirty eigenvalues with error < 0. 04 %. extensions to potentials with linear combinations of terms such as - a / r + br and applications to spatially - symmetric few - body problems are discussed.
|
arxiv:math-ph/0006025
|
the blockchain technology is believed by many to be a game changer in many application domains, especially financial applications. while the first generation of blockchain technology ( i. e., blockchain 1. 0 ) is almost exclusively used for cryptocurrency purposes, the second generation ( i. e., blockchain 2. 0 ), as represented by ethereum, is an open and decentralized platform enabling a new paradigm of computing - - - decentralized applications ( dapps ) running on top of blockchains. the rich applications and semantics of dapps inevitably introduce many security vulnerabilities, which have no counterparts in pure cryptocurrency systems like bitcoin. since ethereum is a new, yet complex, system, it is imperative to have a systematic and comprehensive understanding on its security from a holistic perspective, which is unavailable. to the best of our knowledge, the present survey, which can also be used as a tutorial, fills this void. in particular, we systematize three aspects of ethereum systems security : vulnerabilities, attacks, and defenses. we draw insights into, among other things, vulnerability root causes, attack consequences, and defense capabilities, which shed light on future research directions.
|
arxiv:1908.04507
|
in this work, we show that verifying the order of a finite group given as a black - box is in the complexity class qcma. this solves an open problem asked by watrous in 2000 in his seminal paper on quantum proofs and directly implies that the group non - membership problem is also in the class qcma, which further proves a conjecture proposed by aaronson and kuperberg in 2006. our techniques also give improved quantum upper bounds on the complexity of many other group - theoretical problems, such as group isomorphism in black - box groups.
|
arxiv:2504.05547
|
a series of sigma models with torsion are analysed which generate their mass dynamically but whose ultra - violet fixed points are non - trivial conformal field theories - - in fact su ( 2 ) wzw models at level $ k $. in contrast to the more familiar situation of asymptotically free theories in which the fixed points are trivial, the sigma models considered here may be termed ` ` asymptotically cft ' '. these theories have previously been conjectured to be quantum integrable ; this is confirmed by postulating a factorizable s - matrix to describe their infra - red behaviour and then carrying out a stringent test of this proposal. the test involves coupling the theory to a conserved charge and evaluating the response of the free - energy both in perturbation theory to one loop and directly from the s - matrix via the thermodynamic bethe ansatz with a chemical potential at zero temperature. comparison of these results provides convincing evidence in favour of the proposed s - matrix ; it also yields the universal coefficients of the beta - function and allows for an evaluation of the mass gap ( the ratio of the physical mass to the $ \ lambda $ - parameter ) to leading order in $ 1 / k $.
|
arxiv:hep-th/9407113
|
the data acquisition system of the lz experiment, the 10 - tonne dark matter detector to be installed at the sanford underground research facility ( surf ), will collect signals from 788 photomultiplier tubes ( pmts ). because the signals from the time projection chamber pmts will be passed through dual - gain amplifiers, the daq system will collect waveforms from a total of 1276 channels, using custom built, 32 - channel, fpga - based digital signal processors. the appropriately conditioned signals will be digitized at 100 mhz with 14 - bit resolution. based on actual measurements with a small - scale prototype system, the lz daq is expected to be able to handle a maximum sparsified data rate of ~ 1500 mb / s. during calibrations, it is estimated that only 33 % of the system resources are utilized. the digital filters that are used for data selection operate with an aggregate throughput in excess of 595, 000 mb / s. data selection decisions are based on, for example, the amount of scintillation ( s1 ) and photoluminescence s2 light, s1 and s2 hit - patterns, and total energy deposition.
|
arxiv:1511.08385
|
in - context learning ( icl ) is a phenomenon where task learning occurs through a prompt sequence without the necessity of parameter updates. icl in multi - headed attention ( mha ) with absolute positional embedding has been the focus of more study than other sequence model varieties. we examine implications of architectural differences between gpt - 2 and llama as well as llama and mamba. we extend work done by garg et al. ( 2022 ) and park et al. ( 2024 ) to gpt - 2 / llama hybrid and llama / mamba hybrid models - examining the interplay between sequence transformation blocks and regressive performance in - context. we note that certain architectural changes cause degraded training efficiency / icl accuracy by converging to suboptimal predictors or converging slower. we also find certain hybrids showing optimistic performance improvements, informing potential future icl - focused architecture modifications. additionally, we propose the " icl regression score ", a scalar metric describing a model ' s whole performance on a specific task. compute limitations impose restrictions on our architecture - space, training duration, number of training runs, function class complexity, and benchmark complexity. to foster reproducible and extensible research, we provide a typed, modular, and extensible python package on which we run all experiments.
|
arxiv:2411.03945
|
we investigate whether present data on helioseismology and solar neutrino fluxes may constrain wimp - - matter interactions in the range of wimp parameters under current exploration in wimp searches. we find that, for a wimp mass of 30 gev, once the effect of the presence of wimps in the sun ' s interior is maximized, the squared isothermal sound speed is modified, with respect to the standard solar model, by at most 0. 4 % at the sun ' s center. the maximal effect on the boron - 8 solar neutrino flux is a reduction of 4. 5 %. larger masses lead to smaller effects. these results imply that present sensitivities in the measurements of solar properties, though greatly improved in recent years, do not provide information or constraints on wimp properties of relevance for dark matter. furthermore, we show that, when current bounds from direct wimp searches are taken into account, the effect induced by wimps with dominant coherent interactions are drastically reduced as compared to the values quoted above. the case of neutralinos in the minimal supersymmetric standard model is also discussed.
|
arxiv:hep-ph/0206211
|
we introduce two kinds of gauge invariants for any finite - dimensional hopf algebra h. when h is semisimple over c, these invariants are respectively, the trace of the map induced by the antipode on the endomorphism ring of a self - dual simple module, and the higher frobenius - schur indicators of the regular representation. we further study the values of these higher indicators in the context of complex semisimple quasi - hopf algebras h. we prove that these indicators are non - negative provided the module category over h is modular, and that for a prime p, the p - th indicator is equal to 1 if, and only if, p is a factor of dim h. as an application, we show the existence of a non - trivial self - dual simple h - module with bounded dimension which is determined by the value of the second indicator.
|
arxiv:0910.1628
|
theorem 1. 2 in their paper arxiv : 1904. 00999v1 [ math. ap ] 30 mar 2019 " reconstruction of unknown cavity by single measurement " is not valid.
|
arxiv:1904.05029
|
this report describes the results of the escf awareness workshop on handling uncertainty for data quality management - challenges from transport and supply chain management that was held on june 5, 2018 in heeze, the netherlands. the goal of this workshop was to create and enhance awareness into data quality management issues that are encountered in practice, for business organizations that aim to integrate a data - analytical mind set into their operations.
|
arxiv:1810.02091
|
the notion of $ l ^ p $ - distributions is introduced on riemannian symmetric spaces of noncompact type and their main properties are established. we use a geometric description for the topology of the space of test functions in terms of the laplace - beltrami operator. the techniques are based on a - priori estimates for elliptic operators. we show that structure theorems, similar to $ \ rn $, hold on symmetric spaces. we give estimates for the convolutions.
|
arxiv:math/0611570
|
we report first - principles calculations of the phonon dispersion spectrum, thermal expansion, and heat capacity of uranium dioxide. the so - called direct method, based on the quasiharmonic approximation, is used to calculate the phonon frequencies within a density functional framework for the electronic structure. the phonon dispersions calculated at the theoretical equilibrium volume agree well with experimental dispersions. the computed phonon density of states ( dos ) compare reasonably well with measurement data, as do also the calculated frequencies of the raman and infrared active modes including the lo / to splitting. to study the pressure dependence of the phonon frequencies we calculate phonon dispersions for several lattice constants. our computed phonon spectra demonstrate the opening of a gap between the optical and acoustic modes induced by pressure. taking into account the phonon contribution to the total free energy of uo $ _ 2 $ its thermal expansion coefficient and heat capacity have been { \ it ab initio } computed. both quantities are in good agreement with available experimental data for temperatures up to about 500 k.
|
arxiv:1110.0984
|
this paper examines a government ' s strategic resource allocation choices when facing an opposing group whose military power is uncertain. we investigate how this uncertainty affects the government ' s decision to divide resources in a way that either guarantees peace, despite unresolved uncertainty, or risks conflict. we find that under low uncertainty, the government prefers distributions which ensure peace, while under high uncertainty, they are willing to risk war. when uncertainty is low, the government ' s allocation is decreasing in uncertainty. when uncertainty is high it is increasing. the latter leads to an increased probability of fighting and falling total welfare.
|
arxiv:2410.14362
|
we performed pairwise comparisons by human raters of jpeg images from mozjpeg, libjpeg - turbo and our new jpegli encoder. when compressing images at a quality similar to libjpeg - turbo quality 95, the jpegli images were 54 % likely to be preferred over both libjpeg - turbo and mozjpeg images, but used only 2. 8 bits per pixel compared to libjpeg - turbo and mozjpeg that used 3. 8 and 3. 5 bits per pixel respectively. the raw ratings and source images are publicly available for further analysis and study.
|
arxiv:2403.18589
|
we associate with a plane meromorphic curve f a tree model t ( f ) based on its contact structure. then we give a description of the y - derivative of f ( resp. the jacobien j ( f, g ) ) in terms of t ( f ) ( resp. t ( fg ) ). we also characterize the regularity of f in terms of its tree and we give a bound for the number of its irregular values.
|
arxiv:1112.3453
|
in this paper we show how to extend the known algorithm of nodal analysis in such a way that, in the case of circuits without nullors and controlled sources ( but allowing for both, independent current and voltage sources ), the system of nodal equations describing the circuit is partitioned into one part, where the nodal variables are explicitly given as linear combinations of the voltage sources and the voltages of certain reference nodes, and another, which contains the node variables of these reference nodes only and which moreover can be read off directly from the given circuit. neither do we need preparational graph transformations, nor do we need to introduce additional current variables ( as in mna ). thus this algorithm is more accessible to students, and consequently more suitable for classroom presentations.
|
arxiv:0903.2158
|
brascamp - - lieb - type, weighted poincar \ ' { e } - type and related analytic inequalities are studied for multidimensional cauchy distributions and more general $ \ kappa $ - concave probability measures ( in the hierarchy of convex measures ). in analogy with the limiting ( infinite - dimensional log - concave ) gaussian model, the weighted inequalities fully describe the measure concentration and large deviation properties of this family of measures. cheeger - type isoperimetric inequalities are investigated similarly, giving rise to a common weight in the class of concave probability measures under consideration.
|
arxiv:0906.1651
|
the contribution of this work is twofold. the first part deals with a hilbert - space version of mccann ' s celebrated result on the existence and uniqueness of monotone measure - preserving maps : given two probability measures $ \ rm p $ and $ \ rm q $ on a separable hilbert space $ \ mathcal { h } $ where $ \ rm p $ does not give mass to " small sets " ( namely, lipschitz hypersurfaces ), we show, without imposing any moment assumptions, that there exists a gradient of convex function $ \ nabla \ psi $ pushing $ { \ rm p } $ forward to $ { \ rm q } $. in case $ \ mathcal { h } $ is infinite - dimensional, $ { \ rm p } $ - a. s. uniqueness is not guaranteed, though. if, however, $ { \ rm q } $ is boundedly supported ( a natural assumption in several statistical applications ), then this gradient is $ { \ rm p } $ a. s. unique. in the second part of the paper, we establish stability results for transport maps in the sense of uniform convergence over compact " regularity sets ". as a consequence, we obtain a central limit theorem for the fluctuations of the optimal quadratic transport cost in a separable hilbert space.
|
arxiv:2305.11751
|
theory suggests that mergers play an important role in shaping galactic discs and stellar haloes, which was observationally confirmed in the mw thanks to gaia data. in this work, aiming to probe the contribution of mergers to the in situ stellar halo formation, we analyse six m31 / mw analogues from the hestia suite of cosmological hydrodynamical zoom - in simulations of the lg. we found that all the hestia galaxies experience between one to four mergers with stellar mass ratios between 0. 2 and 1 relative to the host at the time of the merger. these significant mergers, with a single exception, happened 7 - 11gyr ago. the overall impact of the most massive mergers in hestia is clearly seen as a sharp increase in the orbital eccentricity ( and a corresponding decrease in the rotational velocity vphi of pre - existing disc stars of the main progenitor, thus nicely reproducing the splash -, plume - like feature that was discovered in the mw. we do find a correlation between mergers and close pericentric passages of massive satellites and bursts of star formation in the in situ component. massive mergers sharply increase the disc velocity dispersion of the in situ stars ; however, the latest significant merger often heats up the disc up to the numbers when the contribution of the previous ones is less prominent in the age - velocity dispersion relation. in hestia galaxies, the in situ halo is an important component of the inner stellar halo where its fraction is about 30 - 40 %, while in the outer parts it typically does not exceed ~ 5 % beyond 15 kpc. the simulations suggest that this component of the stellar haloes continues to grow well after mergers conclude ; however, the most significant contribution comes from stars that formed recently before the merger. the orbital analysis of the hestia galaxies suggests that wedges in rmax - zmax space are mainly populated by the stars born between significant mergers.
|
arxiv:2206.04521
|
a tetrad - based procedure is presented for solving einstein ' s field equations for spherically - symmetric systems ; this approach was first discussed by lasenby et al. in the language of geometric algebra. the method is used to derive metrics describing a point mass in a spatially - flat, open and closed expanding universe respectively. in the spatially - flat case, a simple coordinate transformation relates the metric to the corresponding one derived by mcvittie. nonetheless, our use of non - comoving ( ` physical ' ) coordinates greatly facilitates physical interpretation. for the open and closed universes, our metrics describe different spacetimes to the corresponding mcvittie metrics and we believe the latter to be incorrect. in the closed case, our metric possesses an image mass at the antipodal point of the universe. we calculate the geodesic equations for the spatially - flat metric and interpret them. for radial motion in the newtonian limit, the force acting on a test particle consists of the usual $ 1 / r ^ 2 $ inwards component due to the central mass and a cosmological component proportional to $ r $ that is directed outwards ( inwards ) when the expansion of the universe is accelerating ( decelerating ). for the standard $ \ lambda $ cdm concordance cosmology, the cosmological force reverses direction at about $ z \ approx 0. 67 $. we also derive an invariant fully general - relativistic expression, valid for arbitrary spherically - symmetric systems, for the force required to hold a test particle at rest relative to the central point mass.
|
arxiv:1104.4447
|
in this paper we use and extend the results present in \ cite { 1, 2, 3, 4 } and in particular in \ cite { 4 } to obtain a statistical description of the cosmological constant in a cosmological de sitter universe in terms of massless excitations with planckian effects. first of all, we show that at a classical level, the cosmological constant $ \ lambda > 0 $ can be obtained only for $ t \ rightarrow 0 $. similarly to the black hole case, when quantum effects are taken into account, a representation for $ \ lambda $ is possible in terms of massless excitations, provided that quantum corrections to the misner - sharp mass are considered. moreover, thanks to quantum fluctuations, an effective cosmological constant arises depending on the physical scale under consideration, thus representing a possible solution to the cosmological constant problem without introducing a quintessence field. the smalness of the actual value for $ \ lambda $ can be due to the existence of a quantum decoherence scale above the planck length such that the spacetime evolves as a pure de sitter universe with a small averaged cosmological constant frozen in the lowest energy state.
|
arxiv:1810.00683
|
we develop a scheme for generating a universal qubit cluster state using probabilistic bell measurements without the need for feed - forward or long - time quantum memories. borrowing ideas from percolation theory we numerically show that using unambiguous bell measurements that succeed with 75 % success probability, one could build a cluster state with an underlying pyrochlore geometry such that the probability of having a spanning cluster in a chosen direction approaches unity in the limit of an infinite lattice size. the initial resources required for the generation of a universal state in our protocol are 3 - qubit cluster states that are within experimental reach and are a minimal resource for a bell - measurement - based percolation proposal. since single and multi - photon losses can be detected in bell measurements, our protocol raises the prospect of a fully error - robust scheme.
|
arxiv:1410.3753
|
this work highlights the existence of partial symmetries in large families of iterated plethystic coefficients. the plethystic coefficients involved come from the expansion in the schur basis of iterated plethysms of schur functions indexed by one - row partitions. the partial symmetries are described in terms of an involution on partitions, the flip involution, that generalizes the ubiquitous $ \ omega $ involution. schur - positive symmetric functions possessing this partial symmetry are termed flip - symmetric. the operation of taking plethysm with $ s _ \ lambda $ preserves flip - symmetry, provided that $ \ lambda $ is a partition of two. explicit formulas for the iterated plethysms $ s _ 2 \ circ s _ b \ circ s _ a $ and $ s _ c \ circ s _ 2 \ circ s _ a $, with $ a, $ $ b, $ and $ c $ $ \ ge $ $ 2 $ allow us to show that these two families of iterated plethysms are flip - symmetric. the article concludes with some observations, remarks, and open questions on the unimodality and asymptotic normality of certain flip - symmetric sequences of iterated plethystic coefficients.
|
arxiv:2201.00240
|
this letter reports results from the nemo - 3 experiment based on an exposure of 1275 days with 661g of 130te in the form of enriched and natural tellurium foils. the double beta decay rate of 130te is found to be greater than zero with a significance of 7. 7 standard deviations and the half - life is measured to be t1 / 2 = ( 7. 0 + / - 0. 9 ( stat ) + / - 1. 1 ( syst ) ) x 10 ^ { 20 } yr. this represents the most precise measurement of this half - life yet published and the first real - time observation of this decay.
|
arxiv:1104.3716
|
towards the study of the kashiwara b ( infinity ) crystal, sets h ^ t of functions were introduced given by equivalence classes of unordered partitions satisfying certain boundary conditions. here it is shown that h ^ t is a catalan set of order t, that is to say the cardinality of h ^ t is the t - th catalan number c ( t ). this is a new description of a catalan set and moreover admits some remarkable features. thus to h ^ t there is an associated labelled graph g _ t which is shown to have a canonical decomposition into ( t - 1 )! subgraphs each with 2 ^ { t - 1 } vertices. these subgraphs, called s - graphs, have some tight properties which are needed for the study of b ( infinity ). they are described as labelled hypercubes whose edges connecting vertices with equal labels are missing. it is shown that the number of distinct hypercubes so obtained is again a catalan number, namely c ( t - 1 ). they define functions which depend on a coefficient set of non - negative integers. when the latter are non - zero and pairwise distinct, the vertices of the s - graphs describe distinct functions. moreover this property is retained if certain edges are deleted and certain vertices identified. in particular when these coefficients are all equal and non - zero, it is shown that every hypercube degenerates to a simplex, resulting in exactly t distinct functions, which for example are exactly those needed in the description of b ( infinity ) in type a.
|
arxiv:1512.00406
|
we investigate diffractive events in hadron - hadron collisions, in which two jets are produced and separated by a large rapidity gap. in perturbative qcd, the hard color - singlet object exchanged in the t - channel, and responsible for the rapidity gap, is the balitsky - fadin - kuraev - lipatov ( bfkl ) pomeron. we perform a phenomenological study including the corrections due to next - to - leading logarithms ( nll ). using a renormalisation - group improved nll kernel, we show that the bfkl predictions are in good agreement with the tevatron data, and present predictions which could be tested at the lhc.
|
arxiv:0903.4598
|
using log geometry, we study smoothability of genus zero twisted stable maps to stacky curves relative to a collection of marked points. one application is to smoothing semi - log canonical fibered surfaces with marked singular fibers.
|
arxiv:2108.05324
|
achieving the full promise of the thermodynamic variational objective ( tvo ), a recently proposed variational lower bound on the log evidence involving a one - dimensional riemann integral approximation, requires choosing a " schedule " of sorted discretization points. this paper introduces a bespoke gaussian process bandit optimization method for automatically choosing these points. our approach not only automates their one - time selection, but also dynamically adapts their positions over the course of optimization, leading to improved model learning and inference. we provide theoretical guarantees that our bandit optimization converges to the regret - minimizing choice of integration points. empirical validation of our algorithm is provided in terms of improved learning and inference in variational autoencoders and sigmoid belief networks.
|
arxiv:2010.15750
|
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.