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an overview on several mathematics modules in the transition period of introducing a new curriculum for the foundation programme in engineering at the university of nottingham malaysia campus is discussed in this paper. in order to progress to undergraduate programmes in engineering, previously the students must complete three mathematics modules of 40 credit points in total, for which one of them was a year - long module with 20 credit points. currently under the new curriculum, the students are required to complete five mathematics modules with 10 credit points each. the new curriculum gives positive impacts for both the lecturers and the students in terms of material organization, fully utilizing textbooks and a new arrangement for tutorial sessions. the new curriculum also provides the students with stronger mathematical background in critical thinking and problem solving skills to equip them to embark the undergraduate programmes in engineering.
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arxiv:1503.08921
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we consider a fluid dynamo model generated by the flow on both sides of a moving layer. the magnetic permeability of the layer is larger than that of the flow. we show that there exists an optimum value of magnetic permeability for which the critical magnetic reynolds number for dynamo onset is smaller than for a nonmagnetic material and also smaller than for a layer of infinite magnetic permeability. we present a mechanism that provides an explanation for recent experimental results. a similar effect occurs when the electrical conductivity of the layer is large.
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arxiv:1411.0449
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we build a germ of singular foliation in dimension two with analytical class of separatrix and holonomy representations prescribed. thanks to this construction, we study the link between moduli of a foliation and moduli of its separatrix.
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arxiv:math/0605755
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using a sample of $ 58 \ times 10 ^ 6 $ $ j / \ psi $ events collected with the besii detector, radiative decays $ j / \ psi \ to \ gamma \ gamma v $, where $ v = \ rho $ or $ \ phi $, are studied. a resonance around 1420 mev / c $ ^ 2 $ ( x ( 1424 ) ) is observed in the $ \ gamma \ rho $ mass spectrum. its mass and width are measured to be $ 1424 \ pm 10 ( stat ) \ pm 11 ( sys ) $ mev / c $ ^ 2 $ and $ 101. 0 \ pm 8. 8 \ pm 8. 8 $ mev / c $ ^ 2 $, respectively, and its branching ratio $ b ( j / \ psi \ to \ gamma x ( 1424 ) \ to \ gamma \ gamma \ rho ) $ is determined to be $ ( 1. 07 \ pm0. 17 \ pm 0. 11 ) \ times 10 ^ { - 4 } $. a search for $ x ( 1424 ) \ to \ gamma \ phi $ yields a 95 % c. l. upper limit $ b ( j / \ psi \ to \ gamma x ( 1424 ) \ to \ gamma \ gamma \ phi ) < 0. 82 \ times 10 ^ { - 4 } $.
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arxiv:hep-ex/0403008
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deriving atmospheric parameters of a large sample of stars is of vital importance to understand the formation and evolution of the milky way. photometric surveys, especially those with near - ultraviolet filters, can offer accurate measurements of stellar parameters, with the precision comparable to that from low / medium resolution spectroscopy. in this study, we explore the capability of measuring stellar atmospheric parameters from csst broad - band photometry ( particularly the near - ultraviolet bands ), based on synthetic colors derived from model spectra. we find that colors from the optical and near - ultraviolet filter systems adopted by csst show significant sensitivities to the stellar atmospheric parameters, especially the metallicity. according to our mock data tests, the precision of the photometric metallicity is quite high, with typical values of 0. 17 dex and 0. 20 dex for dwarf and giant stars, respectively. the precision of the effective temperature estimated from broad - band colors are within 50 k.
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arxiv:2401.05948
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the content of the present thesis is based on the papers [ arxiv : 1510. 07886 [ hep - th ] ] [ arxiv : 1505. 02287 [ hep - th ] ] [ arxiv : 1401. 6303 [ hep - th ] ] [ arxiv : 1309. 1402 [ hep - th ] ] [ arxiv : 1305. 4155 [ hep - th ] ] [ arxiv : 1212. 1003 [ hep - th ] ] [ arxiv : 1210. 4734 [ hep - th ] ] and is devoted to the study of aspects of the gribov problem in euclidean yang - mills theories coupled to matter fields. here, we present some, mathematical and physical, evidences that point to the existence of a possible interplay between the gauge sector and the matter sector, in regimes of sufficiently ow energy ( known as the infrared regime ). in other words, we claim that an effect in the vector boson sector of nature due to strong interactions ( the standard model ), at low energies, may be reflected in the matter sector, in the same regime. specifically, we propose that the gribov horizon function of the gauge sector may be felt by the matter field, and that it would be described by an effective non - local mass term attached to the matter field. such a term seems to be dynamically generated and accounts for non - perturbative aspects of the matter field.
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arxiv:1709.00078
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we explore the task of improving persona consistency of dialogue agents. recent models tackling consistency often train with additional natural language inference ( nli ) labels or attach trained extra modules to the generative agent for maintaining consistency. however, such additional labels and training can be demanding. also, we find even the best - performing persona - based agents are insensitive to contradictory words. inspired by social cognition and pragmatics, we endow existing dialogue agents with public self - consciousness on the fly through an imaginary listener. our approach, based on the rational speech acts framework ( frank and goodman, 2012 ), can enforce dialogue agents to refrain from uttering contradiction. we further extend the framework by learning the distractor selection, which has been usually done manually or randomly. results on dialogue nli ( welleck et al., 2019 ) and personachat ( zhang et al., 2018 ) dataset show that our approach reduces contradiction and improves consistency of existing dialogue models. moreover, we show that it can be generalized to improve context - consistency beyond persona in dialogues.
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arxiv:2004.05816
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in this paper, we give a topological version of scott convergence theorem for locally hypercompact spaces. we introduce the notion of $ \ mathcal { s } ^ * _ x $ - convergence on a $ t _ 0 $ topological space $ x $, and define the notion of finitely approximated spaces. monotone determined spaces are natural topological extensions of dcpos. the main results are : ( 1 ) a monotone determined space $ x $ is a locally hypercompact space iff $ \ mathcal { s } ^ * _ x $ - convergence is topological. ( 2 ) for a $ t _ 0 $ space $ x $, $ \ mathcal { s } ^ * _ x $ - convergence is topological iff $ x $ is a finitely approximating space. ( 3 ) if the lawson topology on a monotone determined space $ x $ is compact, then $ x $ is a dcpo endowed with the scott topology.
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arxiv:2209.13253
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we provide evidence that plastic depinning falls into the same class of phenomena as the random organization which was recently studied in periodically driven particle systems [ l. corte et al., nature phys. 4, 420 ( 2008 ) ]. in the plastic flow system, the pinned regime corresponds to the quiescent state and the moving state corresponds to the fluctuating state. when an external force is suddenly applied, the system eventually organizes into one of these two states with a time scale that diverges as a power law at a nonequilibrium transition. we propose a simple experiment to test for this transition in colloidal systems and superconducting vortex systems with random disorder.
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arxiv:0812.3425
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the shock model has successfully explained the observed behaviors of afterglows from long gamma - ray bursts ( grbs ). here we use it to investigate the so - called early afterglows from short grbs, which arises from blast waves that are not decelerated considerably by their surrounding medium. we consider a nearby medium loaded with $ e ^ { \ pm } $ pairs ( beloborodov 2002 ). the temporal behaviors show first a soft - to - hard spectral evolution, from the optical to hard x - ray, and then a usual hard - to - soft evolution after the blast waves begin to decelerate. the light curves show variability, and consist of two peaks. the first peak, due to the pair effect, can be observed in the x - ray, though too faint and too short in the optical. the second peak will be easily detected by { \ it swift }. we show that detections of the double - peak structure in the light curves of early afterglows are very helpful to determine all the shock parameters of short grbs, including both the parameters of the relativistic source and the surroundings. besides, from the requirement that the forward - shock emission in short grbs should be below the batse detection threshold, we give a strong constraint on the shock model parameters. in particular, the initial lorentz factor of the source is limited to be no more than $ \ sim 10 ^ 3 $, and the ambient medium density is inferred to be low, $ n \ la 10 ^ { - 1 } $ cm $ ^ { - 3 } $.
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arxiv:astro-ph/0307388
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identifying new viral threats, and developing long term defences against current and future computer viruses, requires an understanding of their behaviour, structure and capabilities. this paper aims to advance this understanding by further developing the abstract theory of computer viruses. a method of providing abstract definitions for classes of viruses is presented in this paper, which addresses inadequacies of previous techniques. formal definitions for some classes of viruses are then provided, which correspond to existing informal definitions. to relate the abstract theory to the real world, the connection between the abstract definitions and concrete virus implementations is examined. the use of the proposed method in studying the fundamental properties of computer viruses is discussed.
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arxiv:1912.06510
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a short overview is presented of current issues concerning the production and evolution of li, be and b in the milky way. it is argued that the currently popular idea that galactic cosmic rays are accelerated inside metal - rich superbubbles ( which leads ` ` naturally ' ' to the production of primary be and b, as observed ) encounters the same problems as the previously popular idea of supernovae accelerating their own ejecta. a major challenge to theories of light element production is presented by the recent ( and still preliminary ) data suggesting a surprisingly high and $ \ sim $ constant abundance of $ ^ 6 $ li in halo stars ; attempts to explain such a ` ` plateau ' ' are critically examined.
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arxiv:astro-ph/0411569
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sparse regression has recently emerged as an attractive approach for discovering models of spatiotemporally complex dynamics directly from data. in many instances, such models are in the form of nonlinear partial differential equations ( pdes ) ; hence sparse regression typically requires evaluation of various partial derivatives. however, accurate evaluation of derivatives, especially of high order, is infeasible when the data are noisy, which has a dramatic negative effect on the result of regression. we present a novel and rather general approach that addresses this difficulty by using a weak formulation of the problem. for instance, it allows accurate reconstruction of pdes involving high - order derivatives, such as the kuramoto - sivashinsky equation, from data with a considerable amount of noise. the flexibility of our approach also allows reconstruction of pde models that involve latent variables which cannot be measured directly with acceptable accuracy. this is illustrated by reconstructing a model for a weakly turbulent flow in a thin fluid layer, where neither the forcing nor the pressure field is known.
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arxiv:1911.03365
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one of the critical challenges in infrastructural constructions is designing and planning operations and their related resources. the complex interlinked composition of different factors and variables affecting resource productivity has made simulation a powerful approach for operational planning. the construction sector has recently seen a notable surge in applying various simulation tools to enhance further the quality of projects planning, particularly in large - scale infrastructure developments ( e. g., highway construction ). due to possible cost overruns in improper resource allocation, optimizing the design and construction planning stages of megaprojects such as massive pavement projects is essential. recent studies aimed to build a simulation - based strategy in construction designing and planning by combining various simulation approaches ( e. g., discrete - event simulation, system dynamics, agent - based simulation, and hybrid simulation ) to enhance the planning phase. this paper introduces an evolving real - time hybrid simulation technique regarding the projects intrinsic time - varying inputs and factors to optimize the planning of roller compacted concrete ( rcc ) pavement projects. several scenarios are investigated using various resource combinations to achieve the best execution method for delivering concrete to the project. an actual highway project case study validates the proposed model and its application for future projects. this studys findings exhibit the proficiencies of the simulation - based approach in resource planning of rcc pavement projects within the time and cost constraints and their related regulations.
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arxiv:2204.05659
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we focus on the topology and dynamics of minimal sets and levi - flats in surfaces of general type. our method relies on the ergodic theory of riemann surfaces laminations : we use harmonic measures and lyapunov exponents. our first result establishes that minimal sets have large hausdorff dimension when a leaf is simply connected. our second result shows that the class of anosov levi - flats does not occur in surfaces of general type. in particular, by using rigidity results, we obtain that levi - flats are not virtually diffeomorphic to unitary tangent bundles of hyperbolic compact surfaces, nor to hyperbolic torus bundles.
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arxiv:1203.6244
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a parameterized effective hamiltonian approach is used to investigate ktao $ _ 3 $. we find that the experimentally observed anomalous dielectric response of this incipient ferroelectric is well reproduced by this approach, once quantum effects are accounted for. quantum fluctuations suppress the paraelectric - - to - - ferroelectric phase transition ; it is unnecessary to introduce defects to explain the dielectric behavior. the resulting quantum - induced local structure exhibits off - center atomic displacements that display { \ sl longitudinal, needle - like correlations } extending a few lattice constants.
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arxiv:cond-mat/0401318
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it is well known that for a first order system of linear difference equations with rational function coefficients, a solution that is holomorphic in some left half plane can be analytically continued to a meromorphic solution in the whole complex plane. the poles stem from the singularities of the rational function coefficients of the system. just as for differential equations, not all of these singularities necessarily lead to poles in solutions, as they might be what is called removable. in our work, we show how to detect and remove these singularities and further study the connection between poles of solutions and removable singularities. we describe two algorithms to ( partially ) desingularize a given difference system and present a characterization of removable singularities in terms of shifts of the original system.
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arxiv:1802.01150
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charged excitons, or x $ ^ { \ pm } $ - trions, in monolayer transition metal dichalcogenides have binding energies of several tens of mev. together with the neutral exciton x $ ^ 0 $ they dominate the emission spectrum at low and elevated temperatures. we use charge tunable devices based on wse $ _ 2 $ monolayers encapsulated in hexagonal boron nitride, to investigate the difference in binding energy between x $ ^ + $ and x $ ^ - $ and the x $ ^ - $ fine structure. we find in the charge neutral regime, the x $ ^ 0 $ emission accompanied at lower energy by a strong peak close to the longitudinal optical ( lo ) phonon energy. this peak is absent in reflectivity measurements, where only the x $ ^ 0 $ and an excited state of the x $ ^ 0 $ are visible. in the $ n $ - doped regime, we find a closer correspondence between emission and reflectivity as the trion transition with a well - resolved fine - structure splitting of 6 ~ mev for x $ ^ - $ is observed. we present a symmetry analysis of the different x $ ^ + $ and x $ ^ - $ trion states and results of the binding energy calculations. we compare the trion binding energy for the $ n $ - and $ p $ - doped regimes with our model calculations for low carrier concentrations. we demonstrate that the splitting between the x $ ^ + $ and x $ ^ - $ trions as well as the fine structure of the x $ ^ - $ state can be related to the short - range coulomb exchange interaction between the charge carriers.
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arxiv:1705.02110
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the manga project has obtained ifu data for several thousand nearby galaxies, including barred galaxies. with the two dimensional spectral and kinematic information provided by ifus, we can measure the pattern speed of a barred galaxy, which determines the bar dynamics. we apply the non - parametric method proposed by tremaine \ & weinberg to estimate the bar pattern speed for 53 barred galaxies, making this the largest sample studied so far in this way. our sample is selected from the manga first public data release as part of sdss data release 13 according mainly to the axis ratio and position angle difference between the bar and disc, while kinematic data is from the later sdss data release 14. we have used both the photometric position angle from the photometric image and the kinematic position angle from the stellar velocity map to derive the pattern speed. combining three independent bar length measurements and the circular velocity from jeans anisotropic modelling ( jam ), we also determine the dimensionless ratio $ \ cal { r } $ of the corotation radius to the bar length. we find that the galaxy ' s position angle is the main uncertainty in determining the bar pattern speed. the kinematic position angle leads to fewer ultrafast bars than the photometric position angle, and this could be due to the method of measuring the kinematic position angle. we study the dependence of $ \ cal { r } $ values on galaxy properties such as the dark matter fraction from jam modelling and the stellar age and metallicity from stellar population synthesis ( sps ). a positive correlation between the bar length and bar strength is found : the longer the bar, the stronger the bar. however, no other significant correlations are found. this may result from errors in deriving the $ \ cal { r } $ values or from the complex formation and slowdown processes of galactic bars.
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arxiv:1810.03257
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we present a unified approach for determining and proving obstructions to small - time local controllability of scalar - input control systems. our approach views obstructions to controllability as resulting from interpolation inequalities between the functionals associated with the formal lie brackets of the system. using this approach, we give compact unified proofs of all known necessary conditions, we prove a conjecture of 1986 due to kawski, and we derive entirely new obstructions. our work doubles the number of previously - known necessary conditions, all established in the 1980s. in particular, for the third quadratic bracket, we derive a new necessary condition which is complementary to the agrachev - gamkrelidze sufficient ones. we rely on a recent magnus - type representation formula for the state, a new hall basis of the free lie algebra over two generators, an appropriate use of sussmann ' s infinite product to compute the magnus expansion, and gagliardo - nirenberg interpolation inequalities.
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arxiv:2205.14114
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this work presents a bunched of promising technologies to treat blind people : the bionic eyes. the strategy is to combine a retina implant with software capable to interpret the information received. along this line of thinking, projects such as retinal prosthetic strategy with the capacity to restore normal vision from weill medical college of cornell university project, update on retinal prosthetic research from the boston retinal implant project, and restoration of vision using wireless cortical implants from monash vision group project, have shown in a different context the use of technologies that commits to bring the vision through its use.
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arxiv:2203.17200
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despite recent progress, laminar - turbulent coexistence in transitional planar wall - bounded shear flows is still not well understood. contrasting with the processes by which chaotic flow inside turbulent patches is sustained at the local ( minimal flow unit ) scale, the mechanisms controlling the obliqueness of laminar - turbulent interfaces typically observed all along the coexistence range are still mysterious. an extension of waleffe ' s approach [ phys. fluids 9 ( 1997 ) 883 - - 900 ] is used to show that, already at the local scale, drift flows breaking the problem ' s spanwise symmetry are generated just by slightly detuning the modes involved in the self - sustainment process. this opens perspectives for theorizing the formation of laminar - turbulent patterns.
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arxiv:1712.05333
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given a finitely presented group $ g $, hopf ' s formula expresses the second integral homology of $ g $ in terms of generators and relators. we give an algorithm that exploits hopf ' s formula to estimate $ h _ 2 ( g ; k ) $, with coefficients in a finite field k, and give examples using $ g = sl _ 2 $ over specific rings of integers. these examples are related to a conjecture of quillen.
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arxiv:0901.2610
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let $ x $ be a compact riemann surface of genus $ g \ geq 3 $ and let $ \ mathcal { m } _ { \ mathrm { par } } $ be the moduli space of semistable parabolic bundles over $ x $. let $ \ mathcal { m } _ { \ mathrm { parh } } $ denote the moduli space of semistable parabolic higgs bundles over $ x $. in this article, we study the picard group of $ \ mathcal { m } _ { \ mathrm { par } } $ and $ \ mathcal { m } _ { \ mathrm { parh } } $.
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arxiv:2211.14418
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advanced gravitational wave detectors, currently under construction, are expected to directly observe gravitational wave signals of astrophysical origin. the einstein telescope, a third - generation gravitational wave detector, has been proposed in order to fully open up the emerging field of gravitational wave astronomy. in this article we describe sensitivity models for the einstein telescope and investigate potential limits imposed by fundamental noise sources. a special focus is set on evaluating the frequency band below 10hz where a complex mixture of seismic, gravity gradient, suspension thermal and radiation pressure noise dominates. we develop the most accurate sensitivity model, referred to as et - d, for a third - generation detector so far, including the most relevant fundamental noise contributions.
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arxiv:1012.0908
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recently a bps alice string has been found in a $ u ( 1 ) \ times su ( 2 ) $ gauge theory coupled with a charged complex adjoint scalar field arxiv : 1703. 08971. it is a half bps state preserving a half of supercharges when embedded into a supersymmetric gauge theory. in this paper, we study zero modes of a bps alice string. after presenting $ u ( 1 ) $ and translational zero modes, we construct the effective action of these modes. in contrast to previous analysis of the conventional alice string for which only large distance behaviors are known, we can perform calculation exactly in the full space thanks to bps properties.
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arxiv:1706.10212
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we propose the automata - based multiparty protocols framework ( amp ) for top - down protocol development. the framework features a new very general formalism for global protocol specifications called protocol state machines ( psms ), communicating state machines ( csms ) as specifications for local participants, and a type system to check a $ \ pi $ - calculus with session interleaving and delegation against the csm specification. moreover, we define a large class of psms, called " tame ", for which we provide a sound and complete pspace projection operation that computes a csm describing the same protocol as a given psm if one exists. we propose these components as a backwards - compatible new backend for frameworks in the style of multiparty session types. in comparison to the latter, amp offers a considerable improvement in expressivity, decoupling of the various components ( e. g. projection and typing ), and robustness ( thanks to the complete projection ).
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arxiv:2501.16977
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we consider asymtotically anti - de sitter spacetimes in general dimensions. we review the origin of infrared divergences in the on - shell gravitational action, and the construction of the renormalized on - shell action by the addition of boundary counterterms. in odd dimensions, the renormalized on - shell action is not invariant under bulk diffeomorphisms that yield conformal transformations in the boundary ( holographic weyl anomaly ). we obtain formulae for the gravitational stress energy tensor, defined as the metric variation of the renormalized on - shell action, in terms of coefficients in the asymptotic expansion of the metric near infinity. the stress energy tensor transforms anomalously under bulk diffeomorphisms broken by infrared divergences.
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arxiv:hep-th/0010138
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tunneling spectroscopy measurements are often used to probe the energy spectrum of andreev bound states ( abss ) in semiconductor - superconductor hybrids. recently, this spectroscopy technique has been incorporated into planar josephson junctions ( jjs ) formed in two - dimensional electron gases, a potential platform to engineer phase - controlled topological superconductivity. here, we perform abs spectroscopy at the two ends of planar jjs and study the effects of the magnetic vector potential on the abs spectrum. we show that the local superconducting phase difference arising from the vector potential is equal in magnitude and opposite in sign at the two ends, in agreement with a model that assumes localized abss near the tunnel barriers. complemented with microscopic simulations, our experiments demonstrate that the local phase difference can be used to estimate the relative position of localized abss separated by a few hundred nanometers.
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arxiv:2207.06933
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experimental data from the reaction of an 8. 0 gev / c pi - beam incident on a 197au target have been analyzed in order to investigate the integrated breakup time scale for hot residues. alpha - particle energy spectra and particle angular distributions supported by a momentum tensor analysis suggest that at large excitation energy, above 3 - 5 mev / nucleon, light - charged particles are emitted prior to or at the same time as the emission of the heavy fragments. comparison with the smm and gemini models is presented. a binary fission - like mechanism fits the experimental data at low excitation energies, but seems unable to reproduce the data at excitation energies above 3 - 5 mev / nucleon.
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arxiv:nucl-ex/0009012
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biometric systems have to address many requirements, such as large population coverage, demographic diversity, varied deployment environment, as well as practical aspects like performance and spoofing attacks. traditional unimodal biometric systems do not fully meet the aforementioned requirements making them vulnerable and susceptible to different types of attacks. in response to that, modern biometric systems combine multiple biometric modalities at different fusion levels. the fused score is decisive to classify an unknown user as a genuine or impostor. in this paper, we evaluate combinations of score normalization and fusion techniques using two modalities ( fingerprint and finger - vein ) with the goal of identifying which one achieves better improvement rate over traditional unimodal biometric systems. the individual scores obtained from finger - veins and fingerprints are combined at score level using three score normalization techniques ( min - max, z - score, hyperbolic tangent ) and four score fusion approaches ( minimum score, maximum score, simple sum, user weighting ). the experimental results proved that the combination of hyperbolic tangent score normalization technique with the simple sum fusion approach achieve the best improvement rate of 99. 98 %.
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arxiv:1805.10666
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discrete - time hidden markov models ( hmms ) have become an immensely popular tool for inferring latent animal behaviors from telemetry data. here we introduce an open - source r package, momentuhmm, that addresses many of the deficiencies in existing hmm software. features include : 1 ) data pre - processing and visualization ; 2 ) user - specified probability distributions for an unlimited number of data streams and latent behavior states ; 3 ) biased and correlated random walk movement models, including " activity centers " associated with attractive or repulsive forces ; 4 ) user - specified design matrices and constraints for covariate modelling of parameters using formulas familiar to most r users ; 5 ) multiple imputation methods that account for measurement error and temporally - irregular or missing data ; 6 ) seamless integration of spatio - temporal covariate raster data ; 7 ) cosinor and spline models for cyclical and other complicated patterns ; 8 ) model checking and selection ; and 9 ) simulation. momentuhmm considerably extends the capabilities of existing hmm software while accounting for common challenges associated with telemetery data. it therefore facilitates more realistic hypothesis - driven animal movement analyses that have hitherto been largely inaccessible to non - statisticians. while motivated by telemetry data, the package can be used for analyzing any type of data that is amenable to hmms. practitioners interested in additional features are encouraged to contact the authors.
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arxiv:1710.03786
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we develop a technique for removing stellar variability in the light curves of $ \ delta $ - scuti and similar stars. our technique, which we name the linear algorithm for significance reduction ( lasr ), subtracts oscillations from a time series by minimizing their statistical significance in frequency space. we demonstrate that lasr can subtract variable signals of near - arbitrary complexity and can robustly handle close frequency pairs and overtone frequencies. we demonstrate that our algorithm performs an equivalent fit as prewhitening to the straightforward variable signal of kic 9700322. we also show that lasr provides a better fit to seismic activity than prewhitening in the case of the complex $ \ delta $ - scuti koi - 976.
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arxiv:1804.03653
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the von neumann entropy plays a vital role in quantum information theory. the von neumann entropy determines, e. g., the capacities of quantum channels. also, entropies of composite quantum systems are important for future quantum networks, and their characterization is related to the quantum marginal problem. furthermore, they play a role in quantum thermodynamics. in this thesis the set of quantum entropies of multipartite quantum systems is studied. the problem of its characterization is not new - - however, progress has been sparse, indicating that the problem might be hard and that new methods might be needed. here, a variety of different and complementary approaches are taken. first, i look at global properties. it is known that the von neumann entropy region - - just like its classical counterpart - - forms a convex cone. i describe the symmetries of this cone and highlight geometric similarities and differences to the classical entropy cone. in a different approach, i utilize the local geometric properties of extremal rays of a cone. i show that quantum states whose entropy lies on such an extremal ray of the quantum entropy cone have a very simple structure. as the set of all quantum states is very complicated, i look at a simple subset called stabilizer states. i improve on previously known results by showing that under a technical condition on the local dimension, entropies of stabilizer states respect an additional class of information inequalities that is valid for random variables from linear codes. in a last approach i find a representation - theoretic formulation of the classical marginal problem simplifying the comparison with its quantum mechanical counterpart. this novel correspondence yields a simplified formulation of the group characterization of classical entropies ( ieee trans. inf. theory, 48 ( 7 ) : 1992 - 1995, 2002 ) in purely combinatorial terms.
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arxiv:1810.12845
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in this report we examine topics relating to previous single j shell model results. a common thread in the two problems is that they both involve the isospin variable in an important way.
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arxiv:nucl-th/0406039
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to study population dynamics, ecologists and wildlife biologists use relative abundance data, which are often subject to temporal preferential sampling. temporal preferential sampling occurs when sampling effort varies across time. to account for preferential sampling, we specify a bayesian hierarchical abundance model that considers the dependence between observation times and the ecological process of interest. the proposed model improves abundance estimates during periods of infrequent observation and accounts for temporal preferential sampling in discrete time. additionally, our model facilitates posterior inference for population growth rates and mechanistic phenometrics. we apply our model to analyze both simulated data and mosquito count data collected by the national ecological observatory network. in the second case study, we characterize the population growth rate and abundance of several mosquito species in the aedes genus.
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arxiv:2212.05180
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in this paper we present an approach towards the comprehensive analysis of the non - integrability of differential equations in the form $ \ ddot x = f ( x, t ) $ which is analogous to hamiltonian systems with 1 + 1 / 2 degree of freedom. in particular, we analyze the non - integrability of some important families of differential equations such as painlev \ ' e ii, sitnikov and hill - schr \ " odinger equation. we emphasize in painlev \ ' e ii, showing its non - integrability through three different hamiltonian systems, and also in sitnikov in which two different version including numerical results are shown. the main tool to study the non - integrability of these kind of hamiltonian systems is morales - ramis theory. this paper is a very slight improvement of the talk with the almost - same title delivered by the author in siam conference on applications of dynamical systems 2007.
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arxiv:0808.3028
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we consider a three dimensional system consisting of a large number of small spherical particles, which move due to gravity or with laminar shear and which merge when they cross. a size ratio criterion may be applied to restrict merging to similar sized particles ( locality of interactions ) or particles dissimilar in size ( nonlocality ). we perform direct numerical simulations ( dns ) of this particle system and study the resulting mass spectra. in mean field approximation, these systems can be described by the smoluchowski coagulation equation ( sce ). dns of the particle system with locality enforced show the scaling solutions or kolmogorov - zakharov spectra for the sce, signifying a constant mass flux. dns without a size ratio criterion show - 4 / 3 scaling for large particles in a system with gravity, signifying a constant flux in number of particles, which we also find analytically by assuming nonlocality of interactions in the sce. for laminar shear, this nonlocality is only marginal, and our dns show that a correction to the scaling solution is required.
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arxiv:0809.1246
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we study g - graded artinian algebras having poincar \ ' e duality and their lefschetz properties. we prove the equivalence between the toric setup and the g - graded one, and a hessian criterion in the g - graded setup. we provide an application to toric geometry.
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arxiv:2407.17811
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multibody dynamics simulations have become widely used tools for vehicle systems analysis and design. as this approach evolves, it becomes able to provide additional information for various types of analyses. one very important direction is the optimization of multibody systems. sensitivity analysis of multibody system dynamics is essential for design optimization. dynamic sensitivities, when needed, are often calculated by means of finite differences. however, depending of the number of parameters involved, this procedure can be computationally expensive. moreover, in many cases the results suffer from low accuracy when real perturbations are used. this paper develops the adjoint sensitivity analysis of multibody systems in the context of penalty formulations. the resulting sensitivities are applied to perform dynamical optimization of a full vehicle system.
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arxiv:1405.5197
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we study the conditions for convective instability in rotating, non - magnetic proto - - neutron stars. the criteria that determine stability of nascent neutron stars are analogous to the solberg - - hoiland conditions but including the presence of lepton gradients. our results show that, for standard angular velocity profiles, convectively unstable modes with wave - vectors parallel to the rotation axis are suppressed by a stable angular momentum profile, while unstable modes with wave - vectors perpendicular to the axis remain unaltered. since the wave - vector is perpendicular to the velocity perturbation, the directional selection of the unstable modes may result in fluid motions along the direction of the rotation axis. this occurs in rigidly rotating stars as well as in the inner core of differentially rotating stars. our results provide a natural source of asymmetry for proto - - neutron stars with the only requirement that angular velocities be of the order of the convective characteristic frequency.
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arxiv:astro-ph/0403021
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in this paper, we consider the wave equation with both a viscous kelvin - voigt and frictional damping as a model of viscoelasticity in which we incorporate an internal control with a moving support. we prove the null controllability when the control region, driven by the flow of an ode, covers all the domain. the proof is based upon the interpretation of the system as, roughly, the coupling of a heat equation with an ordinary differential equation ( ode ). the presence of the ode for which there is no propagation along the space variable makes the controllability of the system impossible when the control is confined into a subset in space that does not move. % accordingly, we consider the control on a moving support that, along the time interval, covers the whole domain. the null controllability of the system with a moving control is established in using the observability of the adjoint system and some carleman estimates for a coupled system of a parabolic equation and an ode with the same singular weight, adapted to the geometry of the moving support of the control. this extends to the multi - dimensional case the results by p. martin et al. on the one - dimensional case, employing 1 - d fourier analysis techniques.
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arxiv:1303.3452
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recent studies of femncocr - based high entropy alloys have demonstrated uncommon deformation behaviors such as transformation - induced plasticity, which were largely believed to be restricted to select families of steels. coupled with the potential for entropy stabilization of high symmetry phases at high temperatures, this system represents a promising class of materials for structural applications in extreme environments. yet, transformation - induced plasticity mechanisms are notably sensitive to microstructure parameters and the literature offers examples of deleterious decomposition of high entropy alloys under heat treatment, which raises concerns of resiliency in mechanical performance. here, we evaluate the evolution of microstructure and mechanical properties of a femncocr high entropy alloy after prolonged heat treatment at high temperature. microstructures are found to retain their characteristic austenite / martensite features, with parent face - centered cubic grains partitioned by hexagonal close - packed laths after heat treatment at 1200 c for up to 48 hours. results of mechanical testing reveal an unusual insensitivity of this alloy to grain growth - induced weakening effects. namely, the yield strengths of femncocr samples are observed to remain constant across all heat treatment conditions, despite a near four - fold increase in the grain size. close examination of post - heat treatment microstructures reveals a dramatic decrease in the inter - lath spacing at longer durations, which segments parent austenite grains. this crystal partitioning counteracts conventional grain growth - induced weakening by introducing additional barriers for dislocation pile - up. these results offer new insights into the mechanical resiliency of this transformation - induced plasticity high entropy alloy under prolonged high temperature heat treatment.
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arxiv:2103.05567
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forecasting future events is a fundamental challenge for temporal knowledge graphs ( tkg ). as in real life predicting a mean function is most of the time not sufficient, but the question remains how confident can we be about our prediction? thus, in this work, we will introduce a novel graph neural network architecture ( wgp - nn ) employing ( weighted ) gaussian processes ( gp ) to jointly model the temporal evolution of the occurrence probability of events and their time - dependent uncertainty. especially we employ gaussian processes to model the uncertainty of future links by their ability to predict predictive variance. this is in contrast to existing works, which are only able to express uncertainties in the learned entity representations. moreover, wgp - nn can model parameter - free complex temporal and structural dynamics of tkgs in continuous time. we further demonstrate the model ' s state - of - the - art performance on two real - world benchmark datasets.
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arxiv:2301.04977
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in response to the increasing use of interactive artificial intelligence, the demand for the capacity to handle complex questions has increased. multi - hop question generation aims to generate complex questions that requires multi - step reasoning over several documents. previous studies have predominantly utilized end - to - end models, wherein questions are decoded based on the representation of context documents. however, these approaches lack the ability to explain the reasoning process behind the generated multi - hop questions. additionally, the question rewriting approach, which incrementally increases the question complexity, also has limitations due to the requirement of labeling data for intermediate - stage questions. in this paper, we introduce an end - to - end question rewriting model that increases question complexity through sequential rewriting. the proposed model has the advantage of training with only the final multi - hop questions, without intermediate questions. experimental results demonstrate the effectiveness of our model in generating complex questions, particularly 3 - and 4 - hop questions, which are appropriately paired with input answers. we also prove that our model logically and incrementally increases the complexity of questions, and the generated multi - hop questions are also beneficial for training question answering models.
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arxiv:2404.00571
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we present rijhk imaging of seven radio galaxies from the 7c redshift survey ( 7crs ) which lack strong emission lines and we use these data to investigate their spectral energy distributions ( seds ) with models which constrain their redshifts. six of these seven galaxies have extremely red colours ( r - k > 5. 5 ) and we find that almost all of them lie in the redshift range 1 < z < 2. we also present near - infrared spectroscopy of these galaxies which demonstrate that their seds are not dominated by emission lines, although tentative lines, consistent with h - alpha at z = 1. 45 and z = 1. 61, are found in two objects. although the red colours of the 7crs galaxies can formally be explained by stellar populations which are either very old or young and heavily reddened, independent evidence favours the former hypothesis. at z ~ 1. 5 at least 1 / 4 of powerful radio jets are triggered in massive ( > l * ) galaxies which formed the bulk of their stars several gyr earlier, that is at epochs corresponding to redshifts z > 5. if a similar fraction of all z ~ 1. 5 radio galaxies are old, then extrapolation of the radio luminosity function shows that, depending on the radio source lifetimes, between 10 - 100 % of the near - ir selected extremely red object ( ero ) population undergo a radio outburst at epochs corresponding to 1 < z < 2. an ero found serendipitously in the field of one of the 7crs radio sources appears to be a radio - quiet analogue of the 7crs eros with an emission line likely to be [ oii ] at z = 1. 20. the implication is that some of the most massive elliptical galaxies formed the bulk of their stars at z > 5 and these objects probably undergo at least two periods of agn activity : one at high redshift during which the black hole forms and another one at an epoch corresponding to z ~ 1. 5.
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arxiv:astro-ph/0011082
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ultracold quantum gases of equal spin fermions with short range interactions are often considered free even in the presence of strongly binding spin - up - spin - down pairs. we describe a large class of many - particle schr \ " odinger operators with short - range pair interactions, where this approximation can be justified rigorously.
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arxiv:2201.04362
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in this paper the low energy limit of the bess model is studied in a systematic way. the method consists in eliminating the heavy vector field, by use of its classical equations of motion, in the infinite mass limit. after the elimination of the heavy degrees of freedom we get additional terms to the standard model lagrangian. after a finite renormalization of the ordinary gauge bosons wave functions, and redefinition of the lagrangian couplings in terms of $ m _ z $, the fine structure constant and the fermi constant, we can read directly the deviations from the standard model. by this procedure we can extend a result previously derived to the case in which the heavy vector bosons have a direct coupling to fermions. consequences for the anomalous trilinear couplings are discussed.
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arxiv:hep-ph/9410377
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we study the transport properties of setups with one and two mesoscopic rings threaded by ac magnetic fluxes of the form \ phi ( t ) = \ phi ^ { dc } + \ phi ^ { ac } cos ( \ omega _ 0 t + \ delta ) and connected to two different particle reservoirs. we analyze the conditions to generate a pumped dc current in the adiabatic regime. we also study the symmetry properties of the induced dc current as a function of the static component of the flux, \ phi ^ { dc }, with and without a dc bias voltage applied at the reservoirs. we analyze, in particular, the validity of the onsager - casimir relations for different configurations of the setups.
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arxiv:1211.5525
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in the late 1970 ' s, the axion was proposed as a solution to the strong cp problem, i. e. the puzzle why the strong interactions conserve parity p and the product cp of charge conjugation and parity in spite of the fact that the standard model of elementary particles as a whole violates those symmetries. the original axion was soon ruled out by laboratory experiments and astrophysical considerations, but a new version was invented which is much more weakly coupled and which evades the laboratory and astrophysical constraints. it was dubbed the invisible " axion. however, the axion cannot be arbitrarily weakly coupled because it is overproduced in the early universe by vacuum realignment in the limit of vanishing coupling. the axions produced by vacuum realignment are a form of cold dark matter today. the axion provides a solution then not only to the strong cp problem but also to the dark matter problem. various methods have been proposed to search for dark matter axions and for axions emitted by the sun. their implementation and improvement has led to significant constraints on the notion of an invisible axion. even purely laboratory methods may place significant constraints on invisible axions or axion - like particles. this review discusses the various methods that have been proposed and provides theoretical derivations of their signals.
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arxiv:2003.02206
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we report a detailed and systematic numerical study of wave propagation through a coherently amplifying random one - dimensional medium. the coherent amplification is modeled by introducing a uniform imaginary part in the site energies of the disordered single - band tight binding hamiltonian. several distinct length scales ( regimes ), most of them new, are identified from the behavior of transmittance and reflectance as a function of the material parameters. we show that the transmittance is a non - self - averaging quantity with a well defined mean value. the stationary distribution of the super reflection differs qualitatively from the analytical results obtained within the random phase approximation in strong disorder and amplification regime. the study of the stationary distribution of the phase of the reflected wave reveals the reason for this discrepancy. the applicability of random phase approximation is discussed. we emphasize the dual role played by the lasing medium, as an amplifier as well as a reflector.
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arxiv:cond-mat/9712250
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deep learning networks generally use non - biological learning methods. by contrast, networks based on more biologically plausible learning, such as hebbian learning, show comparatively poor performance and difficulties of implementation. here we show that hebbian learning in hierarchical, convolutional neural networks can be implemented almost trivially with modern deep learning frameworks, by using specific losses whose gradients produce exactly the desired hebbian updates. we provide expressions whose gradients exactly implement a plain hebbian rule ( dw ~ = xy ), grossberg ' s instar rule ( dw ~ = y ( x - w ) ), and oja ' s rule ( dw ~ = y ( x - yw ) ). as an application, we build hebbian convolutional multi - layer networks for object recognition. we observe that higher layers of such networks tend to learn large, simple features ( gabor - like filters and blobs ), explaining the previously reported decrease in decoding performance over successive layers. to combat this tendency, we introduce interventions ( denser activations with sparse plasticity, pruning of connections between layers ) which result in sparser learned features, massively increase performance, and allow information to increase over successive layers. we hypothesize that more advanced techniques ( dynamic stimuli, trace learning, feedback connections, etc. ), together with the massive computational boost offered by modern deep learning frameworks, could greatly improve the performance and biological relevance of multi - layer hebbian networks.
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arxiv:2107.01729
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microelectronic morphogenesis is the creation and maintenance of complex functional structures by microelectronic information within shape - changing materials. only recently has in - built information technology begun to be used to reshape materials and their functions in three dimensions to form smart microdevices and microrobots. electronic information that controls morphology is inheritable like its biological counterpart, genetic information, and is set to open new vistas of technology leading to artificial organisms when coupled with modular design and self - assembly that can make reversible microscopic electrical connections. three core capabilities of cells in organisms, self - maintenance ( homeostatic metabolism utilizing free energy ), self - containment ( distinguishing self from non - self ), and self - reproduction ( cell division with inherited properties ), once well out of reach for technology, are now within the grasp of information - directed materials. construction - aware electronics can be used to proof - read and initiate game - changing error correction in microelectronic self - assembly. furthermore, non - contact communication and electronically supported learning enable one to implement guided self - assembly and enhance functionality. this article reviews the fundamental breakthroughs that have opened the pathway to this prospective path, analyzes the extent and way in which the core properties of life can be addressed and discusses the potential and indeed necessity of such technology for sustainable high technology in society.
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arxiv:2306.17288
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feature matters. how to train a deep network to acquire discriminative features across categories and polymerized features within classes has always been at the core of many computer vision tasks, specially for large - scale recognition systems where test identities are unseen during training and the number of classes could be at million scale. in this paper, we address this problem based on the simple intuition that the cosine distance of features in high - dimensional space should be close enough within one class and far away across categories. to this end, we proposed the congenerous cosine ( coco ) algorithm to simultaneously optimize the cosine similarity among data. it inherits the softmax property to make inter - class features discriminative as well as shares the idea of class centroid in metric learning. unlike previous work where the center is a temporal, statistical variable within one mini - batch during training, the formulated centroid is responsible for clustering inner - class features to enforce them polymerized around the network truncus. coco is bundled with discriminative training and learned end - to - end with stable convergence. experiments on five benchmarks have been extensively conducted to verify the effectiveness of our approach on both small - scale classification task and large - scale human recognition problem.
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arxiv:1710.00870
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i very briefly describe the latest generation near infrared ( 1 - 2. 5 micron ) instruments which are available on, or under development for ` large ' ( d > = 3. 5 m ) telescopes. most of the imagers under construction are limited to relatively small fields, while the spectrometers aim at quite high resolving powers. the alternative instruments which i discuss here are - wide, a relatively low - cost instrument for the prime focus of lbt and / or of tng optimized for deep imaging of very large fields ( 12 ' x12 ' on lbt and 26 ' x26 ' on tng ) through the 1 micron, j, h, k ' broad - band filters. - amici, an ultra - high efficiency, low resolution disperser optimized for collecting complete 0. 9 - 2. 5 micron spectra of very faint objects. this device is mounted in nics ( the ir instrument for tng ) and should soon deliver spectra with quality comparable to that obtained with instruments on 8m class telescopes with similar integration times.
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arxiv:astro-ph/9909108
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when computing systems can tolerate the effects of errors or erasures in their communicated data values, they can trade this tolerance for improved resource efficiency. one method for enabling this tradeoff in the i / o subsystems of computing systems, is to use channel codes that reduce the power needed to send bits on a channel in exchange for bounded errors and erasures on numeric program values - - - value - deviation - bounded ( vdb ) codes. unlike rate distortion codes, which guarantee a bound on the expected value of channel distortion, the probabilistic vdb codes we present guarantee any desired tail distribution on integer distances of words transmitted over a channel. we extend prior work to present tighter upper bounds on the efficiency for vdb codes. we present a new probabilistic vdb encoder that lowers power dissipation in exchange for bounded channel integer distortions. the code we present takes the peculiar approach of changing the channel bit error rate across the ordinal bit positions in a word to reduce power dissipation. we implement the code table generator in a software tool built on the dreal smt solver and we validate the generated codes using monte carlo simulation. we present one realization of hardware to implement the technique, requiring 2 mm $ ^ 2 $ of circuit board area and dissipating less than 0. 5 $ \ mu $ w.
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arxiv:1804.02317
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the familiar generating functionals in quantum field theory fail to be true measures and, so they make the sense only in the framework of the perturbation theory. in our approach, generating functionals are defined strictly as the fourier transforms of gaussian measures in nuclear spaces of multimomentum canonical variables when field momenta correspond to derivatives of fields with respect to all world coordinates, not only to time.
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arxiv:hep-th/9404001
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a model for pulsars with polar - cap magnetic flux density b antiparallel with rotational spin is described. it recognizes the significance of two elementary processes, proton production in electromagnetic showers and photoelectric transitions in ions accelerated through the blackbody radiation field, which must be present at the polar cap in the antiparallel case, but not for pulsars of the opposite spin direction. the two populations are likely to be indistinguishable observationally until curvature radiation pair creation ceases to be possible. the model generates, and provides a physically realistic framework for, the polar - cap potential fluctuations and their time - scales that can produce mode - changes and nulls. the rrats are then no more than an extreme case of the more commonly observed nulls. the model is also able to support the basic features of subpulse drift and to some extent the null - memory phenomenon that is associated with it. unfortunately, it appears that the most important neutron - star parameter for quantitative predictive purposes is the whole - surface temperature, a quantity which is not readily observable at the neutron - star ages concerned.
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arxiv:1302.5260
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sharp features in the primordial power spectrum are a powerful window into the inflationary epoch. to date, the cosmic microwave background ( cmb ) has offered the most sensitive avenue to search for these signatures. in this paper, we demonstrate the power of large - scale structure observations to surpass the cmb as a probe of primordial features. we show that the signatures in galaxy surveys can be separated from the broadband power spectrum and are as robust to the nonlinear evolution of matter as the standard baryon acoustic oscillations. as a result, analyses can exploit a significant range of scales beyond the linear regime available in the datasets. we develop a feature search for large - scale structure, apply it to the final data release of the baryon oscillation spectroscopic survey and find new bounds on oscillatory features that exceed the sensitivity of planck for a significant range of frequencies. moreover, we forecast that the next generation of galaxy surveys, such as desi and euclid, will be able to improve current constraints by up to an order of magnitude over an expanded frequency range.
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arxiv:1906.08758
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( abridged ) we present results from an analysis of the x - ray properties of the ngc 383 galaxy group based on rosat pspc and hri data. x - ray emission can be traced out to ~ 1 mpc, the estimated virial radius of the system. we determine a total mass of 6x10 ^ { 13 } m _ sun for the group inside this radius with a gas mass fraction of 21 %. the intragroup - gas temperature of 1. 5 kev is both consistent with the galaxy velocity dispersion and the x - ray luminosity - temperature relation of groups and clusters suggesting that the group is fairly relaxed. this is also indicated by the almost spherically symmetric appearance of the group ' s x - ray halo. the x - ray properties of the radio galaxy ngc 383 ( 3c 31 ) which is located near the center of the group are discussed. its spectrum is best described by a two - component model, consisting of emission from a low - temperature raymond - smith plasma, and a hard tail. the possible interaction of the radio jets of 3c 31 with the igm is studied. a spatial, spectral and temporal analysis of the einstein source 1e0104 + 3153 located within the field of view is performed, one goal being the identification of the optical counterpart ( with both, a high - redshift bal quasar and a nearby elliptical galaxy, member of a small group, located within the einstein x - ray error circle ). we find evidence that the igm of the small group contributes significantly to the x - ray emission of 1e0104, which can be described by a raymond - smith model of kt ~ 2 kev and a soft x - ray luminosity of l _ x ~ 3 10 ^ { 43 } erg / s.
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arxiv:astro-ph/9902192
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we study outer lipschitz geometry of real semialgebraic or, more general, definable in a polynomially bounded o - minimal structure over the reals, surface germs. in particular, any definable h \ " older triangle is either lipschitz normally embedded or contains some " abnormal " arcs. we show that abnormal arcs constitute finitely many " abnormal zones " in the space of all arcs, and investigate geometric and combinatorial properties of abnormal surface germs. we establish a strong relation between geometry and combinatorics of abnormal h \ " older triangles.
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arxiv:2101.02302
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a covariant - tensor method for $ su ( 2 ) _ { q } $ is described. this tensor method is used to calculate q - deformed clebsch - gordan coefficients. the connection with covariant oscillators and irreducible tensor operators is established. this approach can be extended to other quantum groups.
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arxiv:hep-th/9304073
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the shear - transformation - zone ( stz ) theory of plastic deformation predicts that sufficiently soft, non - crystalline solids are linearly unstable against forming periodic arrays of microstructural shear bands. a limited nonlinear analysis indicates that this instability may be the mechanism responsible for strain softening in both constant - stress and constant - strain - rate experiments. the analysis presented here pertains only to one - dimensional banding patterns in two - dimensional systems, and only to very low temperatures. it uses the rudimentary form of the stz theory in which there is only a single kind of zone rather than a distribution of them with a range of transformation rates. nevertheless, the results are in qualitative agreement with essential features of the available experimental data. the nonlinear theory also implies that harder materials, which do not undergo a microstructural instability, may form isolated shear bands in weak regions or, perhaps, at points of concentrated stress.
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arxiv:cond-mat/0102033
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goupil is a software library designed for the monte carlo transport of low - energy gamma - rays, such as those emitted from radioactive isotopes. the library is distributed as a python module. it implements a dedicated backward sampling algorithm that is highly effective for transporting photons in low density media. in the air, computation time savings of five orders of magnitude are achieved while maintaining an accuracy comparable to that of conventional monte carlo methods, to the nearest percent.
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arxiv:2412.02414
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the strong atomistic spin orbit coupling of holes makes single - shot spin readout measurements difficult because it reduces the spin lifetimes. by integrating the charge sensor into a high bandwidth radio - frequency reflectometry setup we were able to demonstrate single - shot readout of a germanium quantum dot hole spin and measure the spin lifetime. hole spin relaxation times of about 90 $ \ mu $ s at 500 \, mt are reported. by analysing separately the spin - to - charge conversion and charge readout fidelities insight into the processes limiting the visibilities of hole spins has been obtained. the analyses suggest that very high hole visibilities are feasible at realistic experimental conditions underlying the potential of hole spins for the realization of viable qubit devices.
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arxiv:1803.01775
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we prove a liouville type theorem for arbitrarily growing positive viscosity supersolutions of fully nonlinear uniformly elliptic equations in halfspaces. precisely, let $ m ^ - _ { \ lambda, \ lambda } $ be the pucci ' s inf - operator, defined as the infimum of all linear uniformly elliptic operators with ellipticity constants $ \ lambda \ geq \ lambda > 0 $. then, we prove that the inequality $ m ^ - _ { \ lambda, \ lambda } ( d ^ 2u ) + u ^ p \ leq 0 $ does not have any positive viscosity solution in a halfspace provided that $ - 1 \ leq p \ leq ( \ lambda / \ lambda n + 1 ) / ( \ lambda / \ lambda n - 1 ) $, whereas positive solutions do exist if either $ p < - 1 $ or $ p > ( \ lambda / \ lambda ( n - 1 ) + 2 ) / ( \ lambda / \ lambda ( n - 1 ) ) $. this will be accomplished by constructing explicit subsolutions of the homogeneous equation $ m ^ - _ { \ lambda, \ lambda } ( d ^ 2u ) = 0 $ and by proving a nonlinear version in a halfspace of the classical hadamard three - circles theorem for entire superharmonic functions.
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arxiv:1111.1083
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in this paper we study the localization of a derived category of a graded gentle algebra by a subcategory generated by a spherical band object. this object corresponds to a simple closed curve under the equivalence between the perfect derived category of the graded gentle algebra and the partially wrapped fukaya category of the associated graded marked surface, as established by haiden, katzarkov and kontsevich. we describe this localization as a recollement that involves the derived category of a new graded algebra given by quiver and relations. this leads us to the introduction of the class of graded pinched gentle algebras, a generalization of graded gentle algebras. we then show that these algebras are in bijection with graded marked surfaces with conical singularities. moreover, under this correspondence the localization process amounts to the contraction of the closed curve.
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arxiv:2407.04374
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global navigation satellite systems ( gnss ) - based positioning plays a crucial role in various applications, including navigation, transportation, logistics, mapping, and emergency services. traditional gnss positioning methods are model - based and they utilize satellite geometry and the known properties of satellite signals. however, model - based methods have limitations in challenging environments and often lack adaptability to uncertain noise models. this paper highlights recent advances in machine learning ( ml ) and its potential to address these limitations. it covers a broad range of ml methods, including supervised learning, unsupervised learning, deep learning, and hybrid approaches. the survey provides insights into positioning applications related to gnss such as signal analysis, anomaly detection, multi - sensor integration, prediction, and accuracy enhancement using ml. it discusses the strengths, limitations, and challenges of current ml - based approaches for gnss positioning, providing a comprehensive overview of the field.
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arxiv:2406.16873
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we study in the present article the kardar - parisi - zhang ( kpz ) equation $ $ \ partial _ t h ( t, x ) = \ nu \ delta h ( t, x ) + \ lambda | \ nabla h ( t, x ) | ^ 2 + \ sqrt { d } \, \ eta ( t, x ), \ qquad ( t, x ) \ in \ mathbb { r } _ + \ times \ mathbb { r } ^ d $ $ in $ d \ ge 3 $ dimensions in the perturbative regime, i. e. for $ \ lambda > 0 $ small enough and a smooth, bounded, integrable initial condition $ h _ 0 = h ( t = 0, \ cdot ) $. the forcing term $ \ eta $ in the right - hand side is a regularized space - time white noise. the exponential of $ h $ - - its so - called cole - hopf transform - - is known to satisfy a linear pde with multiplicative noise. we prove a large - scale diffusive limit for the solution, in particular a time - integrated heat - kernel behavior for the covariance in a parabolic scaling. the proof is based on a rigorous implementation of k. wilson ' s renormalization group scheme. a double cluster / momentum - decoupling expansion allows for perturbative estimates of the bare resolvent of the cole - hopf linear pde in the small - field region where the noise is not too large, following the broad lines of iagolnitzer - magnen. standard large deviation estimates for $ \ eta $ make it possible to extend the above estimates to the large - field region. finally, we show, by resumming all the by - products of the expansion, that the solution $ h $ may be written in the large - scale limit ( after a suitable galilei transformation ) as a small perturbation of the solution of the underlying linear edwards - wilkinson model ( $ \ lambda = 0 $ ) with renormalized coefficients $ \ nu _ { eff } = \ nu + o ( \ lambda ^ 2 ), d _ { eff } = d + o ( \ lambda ^ 2 ) $.
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arxiv:1702.03122
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in this study, we explore the explainability of neural networks in agriculture and forestry, specifically in fertilizer treatment classification and wood identification. the opaque nature of these models, often considered ' black boxes ', is addressed through an extensive evaluation of state - of - the - art attribution maps ( ams ), also known as class activation maps ( cams ) or saliency maps. our comprehensive qualitative and quantitative analysis of these ams uncovers critical practical limitations. findings reveal that ams frequently fail to consistently highlight crucial features and often misalign with the features considered important by domain experts. these discrepancies raise substantial questions about the utility of ams in understanding the decision - making process of neural networks. our study provides critical insights into the trustworthiness and practicality of ams within the agriculture and forestry sectors, thus facilitating a better understanding of neural networks in these application areas.
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arxiv:2402.11670
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a paper, entitled " well - posedness and optimal decay rates for the viscoelastic kirchhoff equation " was published in 2016, in the journal boletim da sociedade paranaense de matematica. the main results of that paper are stated in theorem 1. 3. section 2 is devoted to stability estimates for the solutions of the galerkin approximation ( 2. 1 ) - ( 2. 2 ) of ( 1. 2 ). section 3 is devoted to the proof of the well - posedness for the kirchhoff equation ( 1. 2 ). this rebuttal is written in view to show the major flaws, and gaps in the proofs of this publication.
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arxiv:2203.17050
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the memorization capacity of neural networks with a given architecture has been thoroughly studied in many works. specifically, it is well - known that memorizing $ n $ samples can be done using a network of constant width, independent of $ n $. however, the required constructions are often quite delicate. in this paper, we consider the natural question of how well feedforward relu neural networks can memorize robustly, namely while being able to withstand adversarial perturbations of a given radius. we establish both upper and lower bounds on the possible radius for general $ l _ p $ norms, implying ( among other things ) that width logarithmic in the number of input samples is necessary and sufficient to achieve robust memorization ( with robustness radius independent of $ n $ ).
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arxiv:2502.11162
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teleportation of an epr pair using triplet in state of the horne - greenberger - zeilinger form to two receivers is considered. it needs a three - particle basis for joint measurement. by contrast the one qubit teleportation the required basis is not maximally entangled. it consists of the states corresponding to the maximally entanglement of two particles only. using outcomes of measurement both receivers can recover an unknown epr state however one of them can not do it separately. teleportation of the n - particle entanglement is discussed.
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arxiv:quant-ph/9906110
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long distance quantum communication is one of the prime goals in the field of quantum information science. with information encoded in the quantum state of photons, existing telecommunication fiber networks can be effectively used as a transport medium. to achieve this goal, a source of robust entangled single photon pairs is required. while time - bin entanglement offers the required robustness, currently used parametric down - conversion sources have limited performance due to multi - pair contributions. we report the realization of a source of single time - bin entangled photon pairs utilizing the biexciton - exciton cascade in a iii / v self - assembled quantum dot. we analyzed the generated photon pairs by an inherently phase - stable interferometry technique, facilitating uninterrupted long integration times. we confirmed the entanglement by performing a quantum state tomography of the emitted photons, which yielded a fidelity of 0. 69 ( 3 ) and a concurrence of 0. 41 ( 6 ).
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arxiv:1305.2081
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latent autoregressive models are useful time series models for the analysis of infectious disease data. evaluation of the likelihood function of latent autoregressive models is intractable and its approximation through simulation - based methods appears as a standard practice. although simulation methods may make the inferential problem feasible, they are often computationally intensive and the quality of the numerical approximation may be difficult to assess. we consider instead a weighted pairwise likelihood approach and explore several computational and methodological aspects including estimation of robust standard errors and the role of numerical integration. the suggested approach is illustrated using monthly data on invasive meningococcal disease infection in greece and italy.
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arxiv:1805.10865
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the dependence of the lyapunov exponent on the closeness parameter, $ \ epsilon $, in tangent bifurcation systems is investigated. we study and illustrate two averaging procedures for defining lyapunov exponents in such systems. first, we develop theoretical expressions for an isolated tangency channel in which the lyapunov exponent is defined on single channel passes. numerical simulations were done to compare theory to measurement across a range of $ \ epsilon $ values. next, as an illustration of defining the lyapunov exponent on many channel passes, a simulation of the intermittent transition in the logistic map is described. the modified theory for the channels is explained and a simple model for the gate entrance rates is constructed. an important correction due to the discrete nature of the iterative flow is identified and incorporated in an improved model. realistic fits to the data were made for the lyapunov exponents from the logistic gate and from the full simulation. a number of additional corrections which could improve the treatment of the gates are identified and briefly discussed.
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arxiv:chao-dyn/9810031
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the growing popular awareness of personal privacy raises the following quandary : what is the new paradigm for collecting and protecting the data produced by ever - increasing sensor devices. most previous studies on co - design of data aggregation and privacy preservation assume that a trusted fusion center adheres to privacy regimes. very recent work has taken steps towards relaxing the assumption by allowing data contributors to locally perturb their own data. although these solutions withhold some data content to mitigate privacy risks, they have been shown to offer insufficient protection against disclosure attacks. aiming at providing a more rigorous data safeguard for the internet of things ( iots ), this paper initiates the study of privacy - preserving data aggregation. we propose a novel paradigm ( called rase ), which can be generalized into a 3 - step sequential procedure, noise addition, followed by random permutation, and then parameter estimation. specially, we design a differentially private randomizer, which carefully guides data contributors to obfuscate the truth. then, a shuffler is employed to receive the noisy data from all data contributors. after that, it breaks the correct linkage between senders and receivers by applying a random permutation. the estimation phase involves using inaccurate data to calculate an approximate aggregate value. extensive simulations are provided to explore the privacy - utility landscape of our rase.
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arxiv:2405.20914
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the structure and vibrational density of states ( vdos ) of polymer glasses are investigated using numerical simulations based on the classical kremer - grest bead - spring model. we focus on the roles of chain length and bending stiffness, the latter being set by imposing three - body angular potentials along chain backbones. upon increasing the chain length and bending stiffness, structural reorganisation leads to volumetric expansion of the material and build - up of internal stresses. the vdos has two dominant bands : a low frequency one corresponding to inter - and intra - chain non - bonding interactions and a high frequency one corresponding principally to vibrations of bonded beads that constitute skeletal chain backbones. upon increasing the steepness of the angular potential, vibrational modes associated with chain bending gradually move from the low - frequency to the high - frequency band. this redistribution of modes is reflected in a reduction of the so - called boson peak upon increasing chain stiffness. remarkably, the finer structure and the peaks of the high - frequency band, and their variations with stiffness, can, for short chains, be explained using an analytical solution derived for a model triatomic molecule. for longer chains, the qualitative evolution of the vdos with chain stiffness is similar, although the distinct peaks observed for short chains become increasingly smoothed - out. our findings can be used to guide a systematic approach to interpretation of brillouin and raman scattering spectra of glassy polymers in future work, with applications in polymer processing diagnostics.
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arxiv:1801.04130
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in this work, we introduce a novel, end - to - end trainable cnn - based architecture to deliver high quality results for grasp detection suitable for a parallel - plate gripper, and semantic segmentation. utilizing this, we propose a novel refinement module that takes advantage of previously calculated grasp detection and semantic segmentation and further increases grasp detection accuracy. our proposed network delivers state - of - the - art accuracy on two popular grasp dataset, namely cornell and jacquard. as additional contribution, we provide a novel dataset extension for the ocid dataset, making it possible to evaluate grasp detection in highly challenging scenes. using this dataset, we show that semantic segmentation can additionally be used to assign grasp candidates to object classes, which can be used to pick specific objects in the scene.
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arxiv:2107.05287
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the tribonacci sequence is a well - known example of third order recurrence sequence, which belongs to a particular class of recursive sequences. in this article, other generalized tribonacci sequence is introduced and defined by $ h _ { n + 2 } = h _ { n + 1 } + h _ { n } + h _ { n - 1 } \ \ ( n \ geq 1 ) $, where $ h _ { 0 } = 3 $, $ h _ { 1 } = 0 $ and $ h _ { 2 } = 2 $. also $ n $ - th power of the generating matrix for this generalized tribonacci sequence is established and some basic properties of this sequence are obtained by matrix methods. there are many elementary formulae relating the various $ h _ { n } $, most of which, since the sequence is defined inductively, are themselves usually proved by induction.
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arxiv:1807.03340
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recent advances in high - fidelity semantic image editing heavily rely on the presumably disentangled latent spaces of the state - of - the - art generative models, such as stylegan. specifically, recent works show that it is possible to achieve decent controllability of attributes in face images via linear shifts along with latent directions. several recent methods address the discovery of such directions, implicitly assuming that the state - of - the - art gans learn the latent spaces with inherently linearly separable attribute distributions and semantic vector arithmetic properties. in our work, we show that nonlinear latent code manipulations realized as flows of a trainable neural ode are beneficial for many practical non - face image domains with more complex non - textured factors of variation. in particular, we investigate a large number of datasets with known attributes and demonstrate that certain attribute manipulations are challenging to obtain with linear shifts only.
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arxiv:2111.14825
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recent work [ j. s. lundeen et al. nature, 474, 188 ( 2011 ) ] directly measured the wavefunction by weakly measuring a variable followed by a normal ( i. e. ` strong ' ) measurement of the complementary variable. we generalize this method to mixed states by considering the weak measurement of the product of the two observables, which, as a non - hermitian operator, is normally unobservable. this generalized method provides mixed states an operational definition related to the operator representation proposed by dirac. uniquely, it can be performed ` in situ ', determing the quantum state without destroying it.
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arxiv:1110.0727
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the amount of surgical data, recorded during video - monitored surgeries, has extremely increased. this paper aims at improving existing solutions for the automated analysis of cataract surgeries in real time. through the analysis of a video recording the operating table, it is possible to know which instruments exit or enter the operating table, and therefore which ones are likely being used by the surgeon. combining these observations with observations from the microscope video should enhance the overall performance of the systems. to this end, the proposed solution is divided into two main parts : one to detect the instruments at the beginning of the surgery and one to update the list of instruments every time a change is detected in the scene. in the first part, the goal is to separate the instruments from the background and from irrelevant objects. for the second, we are interested in detecting the instruments that appear and disappear whenever the surgeon interacts with the table. experiments on a dataset of 36 cataract surgeries validate the good performance of the proposed solution.
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arxiv:1609.05619
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privacy - preserving deep neural network ( dnn ) inference is a necessity in different regulated industries such as healthcare, finance and retail. recently, homomorphic encryption ( he ) has been used as a method to enable analytics while addressing privacy concerns. he enables secure predictions over encrypted data. however, there are several challenges related to the use of he, including dnn size limitations and the lack of support for some operation types. most notably, the commonly used relu activation is not supported under some he schemes. we propose a structured methodology to replace relu with a quadratic polynomial activation. to address the accuracy degradation issue, we use a pre - trained model that trains another he - friendly model, using techniques such as trainable activation functions and knowledge distillation. we demonstrate our methodology on the alexnet architecture, using the chest x - ray and ct datasets for covid - 19 detection. experiments using our approach reduced the gap between the f1 score and accuracy of the models trained with relu and the he - friendly model to within a mere 0. 32 - 5. 3 percent degradation. we also demonstrate our methodology using the squeezenet architecture, for which we observed 7 percent accuracy and f1 improvements over training similar networks with other he - friendly training methods.
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arxiv:2111.03362
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complex systems are hard to define. nevertheless they are more and more frequently encountered. examples include a worldwide airline traffic management system, a global telecommunication or energy infrastructure or even the whole legacy portfolio accumulated for more than thirty years in a large insurance company. there are currently few engineering methods and tools to deal with them in practice. the purpose of this dagstuhl perspectives workshop on model engineering for complex systems was to study the applicability of model driven engineering ( mde ) to the development and management of complex systems. mde is a software engineering field based on few simple and sound principles. its power stems from the assumption of considering everything - engineering artefacts, manipulations of artefacts, etc - as a model. our intuition was that mde may provide the right level of abstraction to move the study of complex systems from an informal goal to more concrete grounds. in order to provide first evidence in support of this intuition, the workshop studied different visions and different approaches to the development and management of different kinds of complex systems. this note presents the summary of the discussions.
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arxiv:1409.6591
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##stitutive models describing the behavior of soil. in 1960, alec skempton carried out an extensive review of the available formulations and experimental data in the literature about the effective stress validity in soil, concrete, and rock in order to reject some of these expressions, as well as clarify what expressions were appropriate according to several working hypotheses, such as stress - strain or strength behavior, saturated or non - saturated media, and rock, concrete or soil behavior. = = roles = = = = = geotechnical investigation = = = geotechnical engineers investigate and determine the properties of subsurface conditions and materials. they also design corresponding earthworks and retaining structures, tunnels, and structure foundations, and may supervise and evaluate sites, which may further involve site monitoring as well as the risk assessment and mitigation of natural hazards. geotechnical engineers and engineering geologists perform geotechnical investigations to obtain information on the physical properties of soil and rock underlying and adjacent to a site to design earthworks and foundations for proposed structures and for the repair of distress to earthworks and structures caused by subsurface conditions. geotechnical investigations involve surface and subsurface exploration of a site, often including subsurface sampling and laboratory testing of retrieved soil samples. sometimes, geophysical methods are also used to obtain data, which include measurement of seismic waves ( pressure, shear, and rayleigh waves ), surface - wave methods and downhole methods, and electromagnetic surveys ( magnetometer, resistivity, and ground - penetrating radar ). electrical tomography can be used to survey soil and rock properties and existing underground infrastructure in construction projects. surface exploration can include on - foot surveys, geological mapping, geophysical methods, and photogrammetry. geological mapping and interpretation of geomorphology are typically completed in consultation with a geologist or engineering geologist. subsurface exploration usually involves in - situ testing ( for example, the standard penetration test and cone penetration test ). the digging of test pits and trenching ( particularly for locating faults and slide planes ) may also be used to learn about soil conditions at depth. large - diameter borings are rarely used due to safety concerns and expense. still, they are sometimes used to allow a geologist or engineer to be lowered into the borehole for direct visual and manual examination of the soil and rock stratigraphy. various soil samplers exist to meet the needs of different engineering projects. the standard penetration test, which uses a thick - walled split spoon sampler, is the most common way to
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https://en.wikipedia.org/wiki/Geotechnical_engineering
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the j - pet detector, which consists of inexpensive plastic scintillators, has demonstrated its potential in the study of fundamental physics. in recent years, a prototype with 192 plastic scintillators arranged in 3 layers has been optimized for the study of positronium decays. this allows performing precision tests of discrete symmetries ( c, p, t ) in the decays of positronium atoms. moreover, thanks to the possibility of measuring the polarization direction of the photon based on compton scattering, the predicted entanglement between the linear polarization of annihilation photons in positronium decays can also be studied. recently, a new j - pet prototype was commissioned, based on a modular design of detection units. each module consists of 13 plastic scintillators and can be used as a stand - alone, compact and portable detection unit. in this paper, the main features of the j - pet detector, the modular prototype and their applications for possible studies with positron and positronium beams are discussed. preliminary results of the first test experiment performed on two detection units in the continuous positron beam recently developed at the antimatter laboratory ( aml ) of trento are also reported.
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arxiv:2301.02832
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we present a mean - field approach to simulating merging processes of two spherical collisionless stellar systems. this approach is realized with a self - consistent field ( scf ) method in which the full spatial dependence of the density and potential of a system is expanded in a set of basis functions for solving poisson ' s equation. in order to apply this scf method to a merging situation where two systems are moving in space, we assign the expansion center to the center of mass of each system, the position of which is followed by a mass - less particle placed at that position initially. merging simulations over a wide range of impact parameters are performed using both an scf code developed here and a tree code. the results of each simulation produced by the two codes show excellent agreement in the evolving morphology of the merging systems and in the density and velocity dispersion profiles of the merged systems. however, comparing the results generated by the tree code to those obtained with the softening - free scf code, we have found that in large impact parameter cases, a softening length of the plummer type introduced in the tree code has an effect of advancing the orbital phase of the two systems in the merging process at late times. we demonstrate that the faster orbital phase originates from the larger convergence length to the pure newtonian force. other application problems suitable to the current scf code are also discussed.
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arxiv:1903.03138
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motivated by the searching for $ bb \ bar { b } \ bar { b } $ states at lhc recently, we calculate the ground - state energies of $ bb \ bar { b } \ bar { b } $ states with quantum numbers $ ij ^ p = 00 ^ +, 01 ^ +, 02 ^ + $ in a nonrelativistic chiral quark model using the gaussian expansion method. in our calculations, two structures, meson - meson and diquark - antidiquark, and their coupling, along with all possible color configurations are considered. it is expected that the studies shall be helpful for the experimental searching of fully - heavy exotic tetraquark states.
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arxiv:1902.00008
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this article aims to provide a novel formalization of the concept of computational irreducibility in terms of the exactness of functorial correspondence between a category of data structures and elementary computations and a corresponding category of ( 1 - dimensional ) cobordisms. we proceed to demonstrate that, by equipping both categories with a symmetric monoidal structure and considering the case of higher - dimensional cobordism categories, we obtain a natural extension of this formalism that serves also to encompass non - deterministic or ` ` multiway ' ' computations, in which one quantifies not only the irreducibility in the behavior of a single ( deterministic ) computation path, but in the branching and merging behavior of an entire ` ` multiway system ' ' of such paths too. we finally outline how, in the most general case, the resulting symmetric monoidal functor may be considered to be adjoint to the functor characterizing the atiyah - segal axiomatization of a functorial quantum field theory. thus, we conclude by arguing that the irreducibility of ( multi ) computations may be thought of as being dual to the locality of time evolution in functorial approaches to quantum mechanics and quantum field theory. in the process, we propose an extension of the methods of standard ( monoidal ) category theory, in which morphisms are effectively equipped with intrinsic computational complexity data, together with an algebra for how those complexities compose ( both in sequence and in parallel, subject to the monoidal structure ).
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arxiv:2301.04690
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this paper presents a new optical integrated sensing and communication ( o - isac ) framework tailored for cost - effective light - emitting diode ( led ) for enhanced internet of things ( iot ) applications. unlike prior research on isac, which predominantly focused on radio frequency ( rf ) band, o - isac capitalizes on the inherent advantages of the optical spectrum, including the ultra - wide license - free bandwidth, immunity to rf interference, and energy efficiency - - attributes crucial for iot communications. the communication and sensing in our o - isac system unfold in two phases : directionless o - isac and directional o - isac. in the first phase, distributed optical access points emit non - directional light for communication and leverage small - aperture imaging principles for sensing. in the second phase, we put forth the concept of optical beamforming, using collimating lenses to concentrate light, resulting in substantial performance enhancements in both communication and sensing. numerical and simulation results demonstrate the feasibility and impressive performance of o - isac benchmarked against optical separate communication and sensing systems.
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arxiv:2305.04395
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reward modeling in large language models is susceptible to reward hacking, causing models to latch onto superficial features such as the tendency to generate lists or unnecessarily long responses. in reinforcement learning from human feedback ( rlhf ) and more generally during post - training flawed reward signals often lead to outputs that optimize for these spurious correlates instead of genuine quality or correctness. we propose context - aware reward modeling ( carmo ), a novel approach that first generates dynamic, context - relevant criteria to ground the reward model before producing reward scores. unlike prior methods that rely on static rubrics, carmo leverages large language models ( llms ) to adaptively create evaluation criteria such as logical consistency, clarity, and depth tailored to the user query. our theoretical analysis shows that such criteria generation can mitigate reward hacking. we further demonstrate that carmo can be distilled into smaller models, reducing the computational cost of alignment. we establish a new state - of - the - art performance in zero - shot settings for generative models, achieving a 2. 1 \ % improvement on reward bench. furthermore, alignment performed on the carmo - curated preference dataset achieves 22. 5 \ % and 21. 1 \ % lc - wr and wr, respectively, on mistral - base ( 7b ).
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arxiv:2410.21545
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we give a recursion for the multivariate rogers - szeg \ " o polynomials, along with another recursive functional equation, and apply them to compute special values. we also consider the sum of all $ q $ - multinomial coefficients of some fixed degree and length, and give a recursion for this sum which follows from the recursion of the multivariate rogers - szeg \ " o polynomials, and generalizes the recursion for the galois numbers. the sum of all $ q $ - multinomial coefficients of degree $ n $ and length $ m $ is the number of flags of length $ m - 1 $ of subspaces of an $ n $ - dimensional vector space over a field with $ q $ elements. we give a combinatorial proof of the recursion for this sum of $ q $ - multinomial coefficients in terms of finite vector spaces.
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arxiv:1011.0984
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we study proton - antiproton annihilation into $ \ lambda _ c \ bar { \ lambda } _ c $ pairs within the generalized parton picture. our starting point is the double handbag diagram which is shown to factorize into soft generalized parton distributions for the $ p \ to \ lambda _ c $ ( and $ \ bar { p } \ to \ bar { \ lambda } _ c $ ) transition and a hard subprocess amplitude for $ u \ bar { u } \ to c \ bar { c } $. thereby the mass of the charm quark is taken as the hard scale so that our results are not restricted to large scattering angles and / or incredibly large energies. modelling the generalized parton distributions for the $ p \ to \ lambda _ c $ transition by an overlap of simple quark - diquark light - cone wave functions we make first predictions for $ p \ to \ lambda _ c $ transition form factors and unpolarized $ p \ bar { p } \ to \ lambda _ c \ bar { \ lambda } _ c $ cross sections. our findings may become interesting in view of forthcoming experiments at fair in darmstadt.
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arxiv:0811.2661
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we consider domain walls ( dw ' s ) between single - mode and bimodal states that occur in coupled nonlinear diffusion ( nld ), real ginzburg - landau ( rgl ), and complex ginzburg - landau ( cgl ) equations with a spatially dependent coupling coefficient. group - velocity terms are added to the nld and rgl equations, which breaks the variational structure of these models. in the simplest case of two coupled nld equations, we reduce the description of stationary configurations to a single second - order ordinary differential equation. we demonstrate analytically that a necessary condition for existence of a stationary dw is that the group - velocity must be below a certain threshold value. above this threshold, dynamical behavior sets in, which we consider in detail. in the cgl equations, the dw may generate spatio - temporal chaos, depending on the nonlinear dispersion.
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arxiv:patt-sol/9609003
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we present the general regular warped solution with 4d minkowski spacetime in six - dimensional gauged supergravity. in this framework, we can easily embed multiple conical branes into the warped geometry by choosing an undetermined holomorphic function. as an example, for the holomorphic function with many zeroes, we find warped solutions with multi - branes and discuss the generalized flux quantization in this case.
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arxiv:hep-th/0510026
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we address the hypothesis that high velocity clouds correspond to the " missing " dwarf galaxies of the local group predicted by cosmological simulations. to this end, we present optical and near - infrared photometry of five additional high velocity clouds, one of which produces lyman series absorption on the sight line towards the quasar ton s210, with sufficient resolution and sensitivity to enable the detection of an associated stellar content. we do not detect significant stellar populations intrinsic to any of the five clouds. in combination with the results from our paper i, which had yielded non detections of stellar content in another five cases, we find that there is a 50 % chance of getting a null result in ten trials if fewer than 7 % of all high velocity clouds contain stars. we conclude that the population of high velocity clouds is an unlikely repository for the " missing " dwarfs of the local group.
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arxiv:astro-ph/0610748
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we study the motion of an overdamped colloidal particle in a time - dependent non - harmonic potential. we demonstrate the first law - like balance between applied work, exchanged heat, and internal energy on the level of a single trajectory. the observed distribution of applied work is distinctly non - gaussian in good agreement with numerical calculations. both the jarzynski relation and a detailed fluctuation theorem are verified with good accuracy.
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arxiv:cond-mat/0512461
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hexagonal boron nitride ( hbn ), having an in - plane hexagonal structure in the sp2 arrangement of atoms, proclaims structural similarity with graphene with only a small lattice mismatch. despite having nearly identical atomic arrangements and exhibiting almost identical properties, the electronic structures of the two materials are fundamentally different. considering the aforementioned context, a new hybrid material with enhanced properties can be evolved combining both materials. this experiment involves liquid phase exfoliation of hbn and two - dimensional nanocomposites of go - hbn with varying hbn and graphene oxide ( go ) ratios. the optical and vibrational studies conducted using uv - vis absorption and raman spectroscopic analysis report the tuning of electron - phonon interaction ( epi ) in the go - hbn nanocomposite as a function of go content ( % ). this interaction depends on disorder - induced electronic and vibrational modifications addressed by urbach energy ( eu ) and asymmetry parameter ( q ), respectively. the epi contribution to the induced disorders estimated from uv - vis absorption spectra is represented as epi strength ( ee - p ) and its impact observed in raman phonon modes is quantified as an asymmetry parameter ( q ). the inverse of the asymmetry parameter is related to ee - p, as ee - p ~ 1 / | q |. here in this article, a linear relationship has been established between eu and the proportional parameter ( k ), where k is determined as the ratio of the intensity of specific raman mode ( i ) and q2, explaining the disorders ' effect on raman line shape. thus a correlation between urbach energy and the asymmetry parameter of raman mode confirms the tuning of epi with go content ( % ) in go - hbn nanocomposite.
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arxiv:2305.01362
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the star formation efficiency ( sfe ) measures the proportion of molecular gas converted into stars, while the star formation rate ( sfr ) indicates the rate at which gas is transformed into stars. here we propose such a model in the framework of a global radial collapse of molecular clouds, where the collapse velocity depends on the density profile and the initial mass - to - radius ratio of molecular clouds, with the collapse velocity accelerating during the collapse process. this simplified analytical model allows us to estimate a lifetime of giant molecular clouds of approximately $ 0. 44 - 7. 36 \ times 10 ^ 7 \, \ rm { yr } $, and a star formation timescale of approximately $ 0. 5 - 5. 88 \ times 10 ^ 6 \, \ rm { yr } $. additionally, we can predict an sfe of approximately $ 1. 59 \, \ % $, and an sfr of roughly $ 1. 85 \, \ rm { m _ { \ odot } \, yr ^ { - 1 } } $ for the milky way in agreement with observations.
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arxiv:2408.16299
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