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we report on the infrared limit of the quenched lattice landau gauge gluon and ghost propagators as well as the strong coupling constant computed from large asymmetric lattices. the infrared lattice propagators are compared with the pure power law solutions from dyson - schwinger equations ( dse ). for the gluon propagator, the lattice data is compatible with the dse solution. the preferred measured gluon exponent being $ \ sim 0. 52 $, favouring a null zero momentum propagator. the lattice ghost propagator shows finite volume effects and, for the volumes considered, the propagator does not follow a pure power law. furthermore, the strong coupling constant is computed and its infrared behaviour investigated.
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arxiv:hep-lat/0609027
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let a be a unital simple direct limit of recursive subhomogeneous c * - algebras with no dimension growth. we give criteria which specify exactly when a has real rank zero, and exactly when a has the property ( sp ) : every nonzero hereditary subalgebra of a contains a nonzero projection. specifically, a has real rank zero if and only if the natural map from k _ 0 ( a ) to the continuous affine functions on the tracial state space has dense range, a has the property ( sp ) if and only if the range of this map contains strictly positive functions with arbitrarily small norm. by comparison with results for unital simple direct limit of homogeneous c * - algebras with no dimension growth, one might hope that weaker conditions might suffice. we give examples to show that several plausible weaker conditions do not suffice for the results above. if a has real rank zero and at most countably many extreme tracial states, we apply results of h. lin to show that a has tracial rank zero and is classifiable.
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arxiv:math/0405265
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we discuss optical colors of 10, 592 asteroids with known orbits selected from a sample of 58, 000 moving objects observed by the sloan digital sky survey ( sdss ). this is more than ten times larger sample that includes both orbital parameters and multi - band photometric measurements than previously available. we confirm that asteroid dynamical families, defined as clusters in orbital parameter space, also strongly segregate in color space. in particular, we demonstrate that the three major asteroid families ( eos, koronis, and themis ), together with the vesta family, represent four main asteroid color types. their distinctive optical colors indicate that the variations in chemical composition within a family are much smaller than the compositional differences between families, and strongly support earlier suggestions that asteroids belonging to a particular family have a common origin. we estimate that over 90 % of asteroids belong to families.
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arxiv:astro-ph/0208098
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we consider in sufficient detail how the berry phase arises in a rotating electric field in a model system with spin one. the goal is to help the student who first encountered this interesting problem, which is fraught with some subtleties that require attention in order not to go astray.
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arxiv:2307.15093
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federated learning is highly susceptible to model poisoning attacks, especially those meticulously crafted for servers. traditional defense methods mainly focus on updating assessments or robust aggregation against manually crafted myopic attacks. when facing advanced attacks, their defense stability is notably insufficient. therefore, it is imperative to develop adaptive defenses against such advanced poisoning attacks. we find that benign clients exhibit significantly higher data distribution stability than malicious clients in federated learning in both cv and nlp tasks. therefore, the malicious clients can be recognized by observing the stability of their data distribution. in this paper, we propose adaaggrl, an rl - based adaptive aggregation method, to defend against sophisticated poisoning attacks. specifically, we first utilize distribution learning to simulate the clients ' data distributions. then, we use the maximum mean discrepancy ( mmd ) to calculate the pairwise similarity of the current local model data distribution, its historical data distribution, and global model data distribution. finally, we use policy learning to adaptively determine the aggregation weights based on the above similarities. experiments on four real - world datasets demonstrate that the proposed defense model significantly outperforms widely adopted defense models for sophisticated attacks.
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arxiv:2406.14217
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we present a systematic framework for the calculation of soft functions that are defined in terms of $ n \ geq2 $ light - like wilson lines. the formalism represents an extension of a method that we developed earlier for the calculation of dijet soft functions to the general $ n $ - jet case. we discuss the technical aspects of this generalisation, focussing on scet - 1 soft functions that obey the non - abelian exponentiation theorem in this contribution. as a first application of our method, we consider the $ n $ - jettiness observable and present numerical results for the $ 1 $ - jettiness and $ 2 $ - jettiness hadron - collider soft functions to next - to - next - to - leading order in the perturbative expansion.
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arxiv:1808.07427
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we introduce a new algorithm for solving unconstrained discrete - time optimal control problems. our method follows a direct multiple shooting approach, and consists of applying the sqp method together with an $ \ ell _ 2 $ augmented lagrangian primal - dual merit function. we use the lqr algorithm to efficiently solve the primal - dual newton - kkt system. as our algorithm is a specialization of npsqp, it inherits its generic properties, including global convergence, fast local convergence, and the lack of need for second order corrections or dimension expansions, improving on existing direct multiple shooting approaches such as acados, altro, gnms, fatrop, and fddp. the solutions of the lqr - shaped subproblems posed by our algorithm can be be parallelized to run in time logarithmic in the number of stages, states, and controls. moreover, as our method avoids sequential rollouts of the nonlinear dynamics, it can run in $ o ( 1 ) $ parallel time per line search iteration. therefore, this paper provides a practical, theoretically sound, and highly parallelizable ( for example, with a gpu ) method for solving nonlinear discrete - time optimal control problems. an open - source jax implementation of this algorithm can be found on github ( joaospinto / primal _ dual _ ilqr ).
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arxiv:2403.00748
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metal artifact correction is a challenging problem in cone beam computed tomography ( cbct ) scanning. metal implants inserted into the anatomy cause severe artifacts in reconstructed images. widely used inpainting - based metal artifact reduction ( mar ) methods require segmentation of metal traces in the projections as a first step, which is a challenging task. one approach is to use a deep learning method to segment metals in the projections. however, the success of deep learning methods is limited by the availability of realistic training data. it is laborious and time consuming to get reliable ground truth annotations due to unclear implant boundaries and large numbers of projections. we propose to use x - ray simulations to generate synthetic metal segmentation training dataset from clinical cbct scans. we compare the effect of simulations with different numbers of photons and also compare several training strategies to augment the available data. we compare our model ' s performance on real clinical scans with conventional region growing threshold - based mar, moving metal artifact reduction method, and a recent deep learning method. we show that simulations with relatively small number of photons are suitable for the metal segmentation task and that training the deep learning model with full size and cropped projections together improves the robustness of the model. we show substantial improvement in the image quality affected by severe motion, voxel size under - sampling, and out - of - fov metals. our method can be easily integrated into the existing projection - based mar pipeline to get improved image quality. this method can provide a novel paradigm to accurately segment metals in cbct projections.
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arxiv:2208.08288
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in this paper we introduce a randomized version of the backward euler method, that is applicable to stiff ordinary differential equations and nonlinear evolution equations with time - irregular coefficients. in the finite - dimensional case, we consider carath \ ' eodory type functions satisfying a one - sided lipschitz condition. after investigating the well - posedness and the stability properties of the randomized scheme, we prove the convergence to the exact solution with a rate of $ 0. 5 $ in the root - mean - square norm assuming only that the coefficient function is square integrable with respect to the temporal parameter. these results are then extended to the numerical solution of infinite - dimensional evolution equations under monotonicity and lipschitz conditions. here we consider a combination of the randomized backward euler scheme with a galerkin finite element method. we obtain error estimates that correspond to the regularity of the exact solution. the practicability of the randomized scheme is also illustrated through several numerical experiments.
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arxiv:1709.01018
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the quantum zeno effect - - suppression of decay by frequent measurements - - was believed to occur only when the response of the detector is so quick that the initial tiny deviation from the exponential decay law is detectable. however, we show that it can occur even for exactly exponentially decaying systems, for which this condition is never satisfied, by considering a realistic case where the detector has a finite energy band of detection. the conventional theories correspond to the limit of an infinite bandwidth. this implies that the zeno effect occurs more widely than expected so far.
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arxiv:quant-ph/0307075
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we present the first x - ray observation of the energetic millisecond pulsar binary psr j1431 - 4715, performed with xmm - newton and complemented with fast optical multi - band photometry acquired with the ultracam instrument at eso - ntt. it is found as a faint x - ray source without a significant orbital modulation. this contrasts with the majority of systems that instead display substantial x - ray orbital variability. the x - ray spectrum is dominated by non - thermal emission and, due to the lack of orbital modulation, does not favour an origin in an intrabinary shock between the pulsar and companion star wind. while thermal emission from the neutron star polar cap cannot be excluded in the soft x - rays, the dominance of synchrotron emission favours an origin in the pulsar magnetosphere that we describe at both x - ray and gamma - ray energies with a synchro - curvature model. the optical multi - colour light curve folded at the 10. 8h orbital period is double - humped, dominated by ellipsoidal effects, but also affected by irradiation. the ultracam light curves are fit with several models encompassing direct heating and a cold spot, or heat redistribution after irradiation either through convection or convection plus diffusion. despite the inability to constrain the best irradiation models, the fits provide consistent system parameters, giving an orbital inclination of 59 $ \ pm $ 6deg and a distance of 3. 1 $ \ pm $ 0. 3 kpc. the companion is found to be an f - type star, underfilling its roche lobe ( f _ rl = 73 $ \ pm $ 4 % ), with a mass of 0. 20 $ \ pm $ 0. 04 m _ sun, confirming the redback status, although hotter than the majority of redbacks. the stellar dayside and nightside temperatures of 7500k and 7400k, respectively, indicate a weak irradiation effect on the companion, likely due to its high intrinsic luminosity. although the pulsar mass cannot be precisely derived, a heavy ( 1. 8 - 2. 2 m _ sun ) neutron star is favoured
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arxiv:2409.02075
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we derive the precise relation between level matching condition and fractional instanton numbers in six dimensional, abelian and supersymmetric orbifolds of e8 x e8 heterotic string theory. the fractional part of the two e8 instanton numbers is explicitly calculated in terms of the gauge twist. this relation is then used to show that the classification of these orbifolds can be given in terms of flat bundles away from the orbifold singularities under the only constraint that the sum of the fractional parts of the gauge instanton numbers match the fractional part of the gravitational instanton number locally at every fixed point. this directly carries over to m - theory on s ^ 1 / z _ 2
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arxiv:hep-th/0009251
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we study a distance graph $ \ gamma _ n $ that is isomorphic to the $ 1 $ - skeleton of an $ n $ - dimensional unit hypercube. we show that every measurable set of positive upper banach density in the plane contains all sufficiently large dilates of $ \ gamma _ n $. this provides the first examples of distance graphs other than the trees for which a dimensionally sharp embedding in positive density sets is known.
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arxiv:2309.14791
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the berry phase of \ pi \ in graphene is derived in a pedagogical way. the ambiguity of how to calculate this value properly is clarified. its connection with the unconventional quantum hall effect in graphene is discussed.
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arxiv:1309.6714
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most businesses impose a supervisory hierarchy on employees to facilitate management, decision - making, and collaboration, yet routine inter - employee communication patterns within workplaces tend to emerge more naturally as a consequence of both supervisory relationships and the needs of the organization. what then is the relationship between a formal organizational structure and the emergent communications between its employees? understanding the nature of this relationship is critical for the successful management of an organization. while scholars of organizational management have proposed theories relating organizational trees to communication dynamics, and separately, network scientists have studied the topological structure of communication patterns in different types of organizations, existing empirical analyses are both lacking in representativeness and limited in size. in fact, much of the methodology used to study the relationship between organizational hierarchy and communication patterns comes from analyses of the enron email corpus, reflecting a uniquely dysfunctional corporate environment. in this paper, we develop new methodology for assessing the relationship between organizational hierarchy and communication dynamics and apply it to microsoft corporation, currently the highest valued company in the world, consisting of approximately 200, 000 employees divided into 88 teams. this reveals distinct communication network structures within and between teams. we then characterize the relationship of routine employee communication patterns to these team supervisory hierarchies, while empirically evaluating several theories of organizational management and performance. to do so, we propose new measures of communication reciprocity and new shortest - path distances for trees to track the frequency of messages passed up, down, and across the organizational hierarchy.
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arxiv:2208.01208
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recently, cui et al. [ nature \ textbf { 621 }, 711 ( 2023 ) ] reported that the jet nozzle of m87 * exhibits a precession with a period of approximately 11 years. this finding strongly suggests that the supermassive black hole in the core of m87 galaxy is a spinning black hole with a tilted accretion disk. in this paper, our aim is to utilize these observations to preliminarily constrain the parameters of the black hole by using the characteristics of the geodesic motion. firstly, we investigate the properties of the spherical orbits and the innermost stable spherical orbits with constant radius. the corresponding angular momentum, energy, and carter constant for both prograde and retrograde orbits are calculated. we find that, compared to equatorial circular orbits, these quantities exhibit significant differences for fixed tilt angles. moreover, the carter constant takes positive values for nonvanishing tilt angles. notably, the presence of misalignment of the orbit angular momentum and black hole spin leads to a precession effect in these spherical orbits. we then make use of these spherical orbits to model the warp radius of the tilted accretion disk, which allows us to determine the corresponding precession period through the motion of massive particles. further comparing with the observation of m87 *, the relationship between the black hole spin and the warp radius is given, through which if one of them is tested, the other one will be effectively determined. additionally, our study establishes an upper bound on the warp radius of the accretion disk. these findings demonstrate that the precession of the jet nozzle offers a promising approach for testing the physics of strong gravitational regions near a supermassive black holes.
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arxiv:2401.17689
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we study the resummation of soft gluon emission corrections to the production of a top - antitop pair in association with a higgs boson at the large hadron collider. starting from a soft - gluon resummation formula derived in previous work, we develop a bespoke parton - level monte carlo program which can be used to calculate the total cross section along with differential distributions. we use this tool to study the phenomenological impact of the resummation to next - to - next - to - leading logarithmic ( nnll ) accuracy, finding that these corrections increase the total cross section and the differential distributions with respect to nlo calculations of the same observables.
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arxiv:1611.00049
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in increasingly autonomous and highly distributed multi - agent systems, centralized coordination becomes impractical and raises the need for governance and enforcement mechanisms from an agent - centric perspective. in our conceptual view, sanctioning norm enforcement is part of this agent - centric approach and they aim at promoting norm compliance while preserving agents ' autonomy. the few works dealing with sanctioning norm enforcement and sanctions from the agent - centric perspective present limitations regarding the representation of sanctions and the comprehensiveness of their norm enforcement process. to address these drawbacks, we propose the npl ( s ), an extension of the npl normative programming language enriched with the representation of norms and sanctions as first - class abstractions. we also propose a bdi normative agent architecture embedding an engine for processing the npl ( s ) language and a set of capabilities for approaching more comprehensively the sanctioning norm enforcement process. we apply our contributions in a case study for improving the robustness of agents ' decision - making in a production automation system.
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arxiv:2403.15128
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maximum mean discrepancies ( mmds ) like the kernel stein discrepancy ( ksd ) have grown central to a wide range of applications, including hypothesis testing, sampler selection, distribution approximation, and variational inference. in each setting, these kernel - based discrepancy measures are required to ( i ) separate a target p from other probability measures or even ( ii ) control weak convergence to p. in this article we derive new sufficient and necessary conditions to ensure ( i ) and ( ii ). for mmds on separable metric spaces, we characterize those kernels that separate bochner embeddable measures and introduce simple conditions for separating all measures with unbounded kernels and for controlling convergence with bounded kernels. we use these results on $ \ mathbb { r } ^ d $ to substantially broaden the known conditions for ksd separation and convergence control and to develop the first ksds known to exactly metrize weak convergence to p. along the way, we highlight the implications of our results for hypothesis testing, measuring and improving sample quality, and sampling with stein variational gradient descent.
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arxiv:2209.12835
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style transfer is a field with growing interest and use cases in deep learning. recent work has shown generative adversarial networks ( gans ) can be used to create realistic images of virtually stained slide images in digital pathology with clinically validated interpretability. digital pathology images are typically of extremely high resolution, making tilewise analysis necessary for deep learning applications. it has been shown that image generators with instance normalization can cause a tiling artifact when a large image is reconstructed from the tilewise analysis. we introduce a novel perceptual embedding consistency loss significantly reducing the tiling artifact created in the reconstructed whole slide image ( wsi ). we validate our results by comparing virtually stained slide images with consecutive real stained tissue slide images. we also demonstrate that our model is more robust to contrast, color and brightness perturbations by running comparative sensitivity analysis tests.
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arxiv:1906.00617
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understanding of the electrical contact properties of semiconductor nanowire ( nw ) field effect transistors ( fets ) plays a crucial role in employing semiconducting nws as building blocks for future nanoelectronic devices and in the study of fundamental physics problems. here, we report on a study of the contact properties of ti / au, a widely used contact metal combination, to individual insb nws via both two - probe and four - probe transport measurements. we show that a schottky barrier of height $ \ phi _ { \ rm { sb } } \ sim20 \ \ rm { mev } $ is present at the metal - insb nw interfaces and its effective height is gate tunable. the contact resistance ( $ r _ { \ rm { c } } $ ) in the insb nwfets is also analyzed by magnetotransport measurements at low temperatures. it is found that $ r _ { \ rm { c } } $ at on - state exhibits a pronounced magnetic field dependent feature, namely it is increased strongly with increasing magnetic field after an onset field $ b _ { \ rm { c } } $. a qualitative picture that takes into account magnetic depopulation of subbands in the nws is provided to explain the observation. our results provide a solid experimental evidence for the presence of a schottky barrier at ti / au - insb nw interfaces and can be used as a basis for design and fabrication of novel insb nw based nanoelectronic devices and quantum devices.
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arxiv:1605.08689
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for every $ n \ geq 4 $ we construct infinitely many mutually not homotopic closed manifolds of dimension $ n $ which admit a negatively curved einstein metric but no locally symmetric metric.
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arxiv:2411.12956
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unlike static documents, version controlled documents are continuously edited by one or more authors. such collaborative revision process makes traditional modeling and visualization techniques inappropriate. in this paper we propose a new representation based on local space - time smoothing that captures important revision patterns. we demonstrate the applicability of our framework using experiments on synthetic and real - world data.
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arxiv:1003.1410
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generative models have gained many researchers ' attention in the last years resulting in models such as stylegan for human face generation or pointflow for the 3d point cloud generation. however, by default, we cannot control its sampling process, i. e., we cannot generate a sample with a specific set of attributes. the current approach is model retraining with additional inputs and different architecture, which requires time and computational resources. we propose a novel approach that enables to a generation of objects with a given set of attributes without retraining the base model. for this purpose, we utilize the normalizing flow models - conditional masked autoregressive flow and conditional real nvp, as a flow plugin network ( fpn ).
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arxiv:2110.04081
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turaev defined a function on the first homology of a rational homology 3 - sphere $ y $ as the minimal rational seifert genus of all knots in this homology class. ni and the first author discovered a lower bound of this function using the heegaard floer $ d $ - invariant and showed that floer simple knots are rational seifert genus minimizers. in this paper, we give a simple reproof of the above results. we then define a version of rational slice genus for knots in the product 4 - manifold $ y \ times i $ and investigate the analogous minimal genus problem. we prove the same lower bound in terms of the $ d $ - invariant formula and the same genus minimizers given by floer simple knots.
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arxiv:2307.06807
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we consider electroweak corrections to higgs boson pair production, taking into account the top quark yukawa and higgs boson self couplings. using differential equations we compute a deep expansion of all master integrals in the high - energy limit and present analytic results for the two - loop box - type form factors. we show that precise numerical results can be obtained even for relatively small values of the higgs boson transverse momentum. we compare against recent numerical results and find good agreement.
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arxiv:2501.17920
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we consider the nls with variable coefficients in dimension $ n \ ge3 $ \ begin { equation * } i \ partial _ t u - lu + f ( u ) = 0, \ qquad lv = \ nabla ^ { b } \ cdot ( a ( x ) \ nabla ^ { b } v ) - c ( x ) v, \ qquad \ nabla ^ { b } = \ nabla + ib ( x ), \ end { equation * } on $ \ mathbb { r } ^ { n } $ or more generally on an exterior domain with dirichlet boundary conditions, for a gauge invariant, defocusing nonlinearity of power type $ f ( u ) \ simeq | u | ^ { \ gamma - 1 } u $. we assume that $ l $ is a small, long range perturbation of $ \ delta $, plus a potential with a large positive part. the first main result of the paper is a bilinear smoothing ( interaction morawetz ) estimate for the solution. as an application, under the conditional assumption that strichartz estimates are valid for the linear flow $ e ^ { itl } $, we prove global well posedness in the energy space for subcritical powers $ \ gamma < 1 + \ frac { 4 } { n - 2 } $, and scattering provided $ \ gamma > 1 + \ frac4n $. when the domain is $ \ mathbb { r } ^ { n } $, by extending the strichartz estimates due to tataru [ tataru08 ], we prove that the conditional assumption is satisfied and deduce well posedness and scattering in the energy space.
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arxiv:1502.00937
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chvatal, roedl, szemeredi and trotter proved that the ramsey numbers of graphs of bounded maximum degree are linear in their order. in previous work, we proved the same result for 3 - uniform hypergraphs. here we extend this result to k - uniform hypergraphs, for any integer k > 3. as in the 3 - uniform case, the main new tool which we prove and use is an embedding lemma for k - uniform hypergraphs of bounded maximum degree into suitable k - uniform ` quasi - random ' hypergraphs.
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arxiv:math/0612351
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superconducting quantum interference devices ( squids ), single flux - quantum ( sfq ) logic circuits, and quantum josephson junction circuits have been developed into a family of superconductor integrated circuit, and are widely applied for subtle magnetic - field measurements, energy - efficient computing, and quantum computing, respectively. they are josephson junction networks composed of josephson junctions and normal resistor - inductor - capacitor ( rlc ) components, working with the fluxoid - quantization principle and josephson effects to achieve unique flux - modulated dynamics and characteristics ; they react to the vector potential of magnetic fields rather than the electric potential. however, the conventional circuit diagrams and nodal analysis methods focus on the electric charges flowing though branches and nodes, ignoring dynamics of the magnetic fluxes flowing from loop to loop. this article introduces a general flux - based circuit theory to unify the analyses of josephson junction circuits and normal rlc circuits. this theory presents a magnetic - flux - generator ( mfg ) concept to unify josephson junctions and normal circuit elements, and abstract both josephson junction circuits and normal rlc circuits as mfg network ; it derives a general network equation to describe dynamics of josephson junction circuits, and invents a kind of magnetic - flux flow ( mff ) diagram to depict the working principles of magnetic - flux flows inside josephson junction circuits. the flux - based theory is complementary to the conventional circuit theories in the design and analysis of superconductor integrated circuits.
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arxiv:2308.01693
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we derive the trial hall resistance formula for the quantum hall metals to address both the integer and fractional quantum hall effects. within the degenerate landau levels, zeeman splitting and level crossings in the presence of changing magnetic - field strength determine the pancharatnam phase retardation, including the phase acceleration or deceleration, which are related to the changes in the phase and group momenta of a wavefunction. we discuss the relevant physical postulates with respect to pancharatnam phase retardation to qualitatively reproduce the measured hall resistance ' s zigzag curve for both the integer and the fractional filling factors. along the way, we give out some hints to falsify our postulates with experiments.
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arxiv:1304.4531
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we give a formula to compute the dimension of the generic component of the moduli space of an irreducible germ of curve in the complex plane.
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arxiv:1610.05998
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differentiable environments have heralded new possibilities for learning control policies by offering rich differentiable information that facilitates gradient - based methods. in comparison to prevailing model - free reinforcement learning approaches, model - based reinforcement learning ( mbrl ) methods exhibit the potential to effectively harness the power of differentiable information for recovering the underlying physical dynamics. however, this presents two primary challenges : effectively utilizing differentiable information to 1 ) construct models with more accurate dynamic prediction and 2 ) enhance the stability of policy training. in this paper, we propose a differentiable information enhanced mbrl method, mb - mix, to address both challenges. firstly, we adopt a sobolev model training approach that penalizes incorrect model gradient outputs, enhancing prediction accuracy and yielding more precise models that faithfully capture system dynamics. secondly, we introduce mixing lengths of truncated learning windows to reduce the variance in policy gradient estimation, resulting in improved stability during policy learning. to validate the effectiveness of our approach in differentiable environments, we provide theoretical analysis and empirical results. notably, our approach outperforms previous model - based and model - free methods, in multiple challenging tasks involving controllable rigid robots such as humanoid robots ' motion control and deformable object manipulation.
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arxiv:2503.01178
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the rapid growth of biomedical literature poses challenges for manual knowledge curation and synthesis. biomedical natural language processing ( bionlp ) automates the process. while large language models ( llms ) have shown promise in general domains, their effectiveness in bionlp tasks remains unclear due to limited benchmarks and practical guidelines. we perform a systematic evaluation of four llms, gpt and llama representatives on 12 bionlp benchmarks across six applications. we compare their zero - shot, few - shot, and fine - tuning performance with traditional fine - tuning of bert or bart models. we examine inconsistencies, missing information, hallucinations, and perform cost analysis. here we show that traditional fine - tuning outperforms zero or few shot llms in most tasks. however, closed - source llms like gpt - 4 excel in reasoning - related tasks such as medical question answering. open source llms still require fine - tuning to close performance gaps. we find issues like missing information and hallucinations in llm outputs. these results offer practical insights for applying llms in bionlp.
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arxiv:2305.16326
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in this paper, we develop bayes and maximum a posteriori probability ( map ) approaches to monotonicity testing. in order to simplify this problem, we consider a simple white gaussian noise model and with the help of the haar transform we reduce it to the equivalent problem of testing positivity of the haar coefficients. this approach permits, in particular, to understand links between monotonicity testing and sparse vectors detection, to construct new tests, and to prove their optimality without supplementary assumptions. the main idea in our construction of multi - level tests is based on some invariance properties of specific probability distributions. along with bayes and map tests, we construct also adaptive multi - level tests that are free from the prior information about the sizes of non - monotonicity segments of the function.
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arxiv:1909.09517
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algebraic models for equivariant rational homotopy theory were developed by triantafillou and scull for finite group actions and $ s ^ 1 $ action, respectively. they showed that given a diagram of rational cohomology algebras from the orbit category of a group $ g $, there is a unique minimal system of dgas and hence a unique equivariant rational homotopy type that is weakly equivalent to it. however, there can be several equivariant rational homotopy types with the same system of cohomology algebras. halperin, stasheff, and others studied the problem of classifying rational homotopy types up to cohomology in the non - equivariant case. in this article, we consider this question in the equivariant case. we prove that when $ \ mathbb { z } _ p $ under suitable conditions, the equivariant rational homotopy types with isomorphic cohomology can be reduced to the non - equivariant case.
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arxiv:2301.06824
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we discuss the asymptotic properties of quantum states density for fundamental ( super ) membrane in the semiclassical approach. the matching of bps part of spectrum for superstring and supermembrane gives the possibility to get stringy results via membrane calculations and vice versa. the brane - black hole correspondence ( on the level of black hole states and brane microstates ) is also studied.
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arxiv:hep-th/9708136
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in this work, a new approach has been developed to obtain numerical solution of linear volterra type integral equations by obtaining asymptotic approximation to solutions. using the classical bernoulli polynomials, a set of orthonormal polynomials have been derived, and these orthonormal polynomials have been used to form an operational matrix of integration which is has been implemented to find numerical or exact solution of non - singular volterra integral equations. two linear volterra integral and two convolution integral equations of second kind have been solved to demonstrate the effectiveness of present method. obtained approximate solutions have been compared with the exact solutions for numerical values. high degree of accuracy of numerical solutions has established the credibility of the present method.
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arxiv:2007.10814
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we prove a new bound to the exponential sum of the form $ $ \ sum _ { h \ sim h } \ delta _ h \ mathop { \ sum _ { m \ sim m } \ sum _ { n \ sim n } } _ { mn \ sim x } a _ { m } b _ { n } \ e \ big ( \ alpha mn + h ( mn + u ) ^ { \ gamma } \ big ), $ $ by a new approach to the type i sum. the sum can be applied to many problems related to piatetski - shapiro primes, which are primes of the form $ \ lfloor n ^ c \ rfloor $. in this paper, we improve the admissible range of the balog - friedlander condition, which leads to an improvement to the ternary goldbach problem with piatetski - shapiro primes. we also investigate the distribution of piatetski - shapiro primes in arithmetic progressions, piatetski - shapiro primes in the intersection of multiple beatty sequences and so on.
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arxiv:2504.11464
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in a distributed computing system operating according to the map - shuffle - reduce framework, coding data prior to storage can be useful both to reduce the latency caused by straggling servers and to decrease the inter - server communication load in the shuffling phase. in prior work, a concatenated coding scheme was proposed for a matrix multiplication task. in this scheme, the outer maximum distance separable ( mds ) code is leveraged to correct erasures caused by stragglers, while the inner repetition code is used to improve the communication efficiency in the shuffling phase by means of coded multicasting. in this work, it is demonstrated that it is possible to leverage the redundancy created by repetition coding in order to increase the rate of the outer mds code and hence to increase the multicasting opportunities in the shuffling phase. as a result, the proposed approach is shown to improve over the best known latency - communication overhead trade - off.
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arxiv:1808.06583
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keyphrases are a very short summary of an input text and provide the main subjects discussed in the text. keyphrase extraction is a useful upstream task and can be used in various natural language processing problems, for example, text summarization and information retrieval, to name a few. however, not all the keyphrases are explicitly mentioned in the body of the text. in real - world examples there are always some topics that are discussed implicitly. extracting such keyphrases requires a generative approach, which is adopted here. in this paper, we try to tackle the problem of keyphrase generation and extraction from news articles using deep sequence - to - sequence models. these models significantly outperform the conventional methods such as topic rank, kpminer, and kea in the task of keyphrase extraction.
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arxiv:2009.12271
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the transiting extrasolar planet wasp - 12 b was found to be one of the most intensely irradiated exoplanets. it is unexpectedly bloated and is losing mass that may accrete into the host star. our aim was to refine the parameters of this intriguing system and search for signs of transit timing variations. we gathered high - precision light curves for two transits of wasp - 12 b. assuming various limb - darkening laws, we generated best - fitting models and redetermined parameters of the system. error estimates were derived by the prayer bead method and monte carlo simulations. system parameters obtained by us are found to agree with previous studies within one sigma. use of the non - linear limb - darkening laws results in the best - fitting models. with two new mid - transit times, the ephemeris was refined to bjd ( tdb ) = ( 2454508. 97682 + / - 0. 00020 ) + ( 1. 09142245 + / - 0. 00000033 ) e. interestingly, indications of transit timing variation are detected at the level of 3. 4 sigma. this signal can be induced by an additional planet in the system. simplified numerical simulations shows that a perturber could be a terrestrial - type planet if both planets are in a low - order orbital resonance. however, we emphasise that further observations are needed to confirm variation and to constrain properties of the perturber.
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arxiv:1102.2421
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we have investigated the longitudinal thermal conductivity of $ \ alpha $ - rucl $ _ { 3 } $, the magnetic state of which is considered to be proximate to a kitaev honeycomb model, along with the spin susceptibility and magnetic specific heat. we found that the temperature dependence of the thermal conductivity exhibits an additional peak around 100 k, which is well above the phonon peak temperature ( $ \ sim $ 50 k ). the higher - temperature peak position is comparable to the temperature scale of the kitaev couplings rather than the n \ ' eel temperatures below 15 k. the additional heat conduction was observed for all five samples used in this study, and was found to be rather immune to a structural phase transition of $ \ alpha $ - rucl $ _ { 3 } $, which suggests its different origin from phonons. combined with experimental results of the magnetic specific heat, our transport measurement suggests strongly that the higher - temperature peak in the thermal conductivity is attributed to itinerant spin excitations associated with the kitaev couplings of $ \ alpha $ - rucl $ _ { 3 } $. a kinetic approximation of the magnetic thermal conductivity yields a mean free path of $ \ sim $ 20 nm at 100 k, which is well longer than the nearest ru - ru distance ( $ \ sim $ 3 \ aa ), suggesting the long - distance coherent propagation of magnetic excitations driven by the kitaev couplings.
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arxiv:1611.04799
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we study evolution of open quadratic fermion systems in the framework of the quantum markovian semigroup approach. we show that the algebra concerning commutators of liouvillians for systems of quadratic interacting fermions of finite number, say $ \ mathcal { n } $, is isomorphic to that of certain affine transformations on the space of square matrices of size $ \ mathcal { n } $. by the use of this algebraic structure, we present a perspective method for solving master equations of quadratic fermion systems. here, we mainly deal with gauge invariant quadratic interacting fermion systems. we briefly mention similar algebraic structures for general quadratic fermion systems and quadratic boson systems. keywords : open quantum system, markovian quantum dynamical system, quadratic interacting fermion, affine transformation, asymptotic behavior, skin effect
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arxiv:2301.06069
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using a notation of corner between edges when graph has a fixed rotation, i. e. cyclical order of edges around vertices, we define combinatorial objects - combinatorial maps as pairs of permutations, one for vertices and one for faces. further, we define multiplication of these objects, that coincides with the multiplication of permutations. we consider closed under multiplication classes of combinatorial maps that consist of closed classes of combinatorial maps with fixed edges where each such class is defined by a knot. one class among them is special, containing selfconjugate maps.
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arxiv:0909.0104
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the population in sweden is growing rapidly due to immigration. in this light, the issue of infrastructure upgrades to provide telecommunication services is of importance. new antennas can be installed at hot spots of user demand, which will require an investment, and / or the clientele expansion can be carried out in a planned manner to promote the exploitation of the infrastructure in the less loaded geographical zones. in this paper, we explore the second alternative. informally speaking, the term infrastructure - stressing describes a user who stays in the zones of high demand, which are prone to produce service failures, if further loaded. we have studied the infrastructure - stressing population in the light of their correlation with geo - demographic segments. this is motivated by the fact that specific geo - demographic segments can be targeted via marketing campaigns. fuzzy logic is applied to create an interface between big data, numeric methods for processing big data and a manager.
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arxiv:1706.03940
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the knowledge of the structure and dynamics of agb - star atmospheres is crucial to better understand the mass loss. the tomographic method, that relies on the design of spectral masks containing lines forming in given ranges of optical depths in the stellar atmosphere, is an ideal technique for this purpose. it is applied to high - resolution spectro - interferometric vlti / amber observations of the mira - type agb star s ori. first, the interferometric visibilities are extracted at wavelengths contributing to the tomographic masks and fitted to those computed from a uniform disk model. this allows the measurement of the geometrical extent of the atmospheric layer probed by the corresponding mask. then, we compare the observed atmospheric extension with those measured from available 1d pulsation codex models and 3d radiative - hydrodynamics co5bold simulations. we found that while the average optical depths probed by the tomographic masks in s ori decrease ( with $ < \ log \ tau _ 0 > = - 0. 45 $, $ - 1. 45 $, and $ - 2. 45 $ from the innermost to the central and outermost layers ), the angular diameters of these layers increase, from 10. 59 $ \ pm $ 0. 09 mas through 11. 84 $ \ pm $ 0. 17 mas, up to 14. 08 $ \ pm $ 0. 15 mas. a similar behavior is observed when the tomographic method is applied to 1d and 3d dynamical models. thus, this study derives, for the first time, a quantitative relation between optical - and geometrical - depth scales when applied to the mira star s ori, or to 1d and 3d dynamical models. in the context of mira - type stars, the knowledge of the link between the optical and geometrical depths opens the way to derive the shock - wave propagation velocity, which can not be directly observed in these stars.
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arxiv:2009.03955
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we present the superconformal gauge theory living on the world - volume of d3 branes probing the toric singularities with horizon the recently discovered sasaki - einstein manifolds l ^ { p, q, r }. various checks of the identification are made by comparing the central charge and the r - charges of the chiral fields with the information that can be extracted from toric geometry. fractional branes are also introduced and the physics of the associated duality cascade discussed.
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arxiv:hep-th/0505220
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with the help of micro - doppler signature, ultra - wideband ( uwb ) through - the - wall radar ( twr ) enables the reconstruction of range and velocity information of limb nodes to accurately identify indoor human activities. however, existing methods are usually trained and validated directly using range - time maps ( rtm ) and doppler - time maps ( dtm ), which have high feature redundancy and poor generalization ability. in order to solve this problem, this paper proposes a human activity micro - doppler signature representation method based on joint boulic - sinusoidal pendulum motion model. in detail, this paper presents a simplified joint boulic - sinusoidal pendulum human motion model by taking head, torso, both hands and feet into consideration improved from boulic - thalmann kinematic model. the paper also calculates the minimum number of key points needed to describe the doppler and micro - doppler information sufficiently. both numerical simulations and experiments are conducted to verify the effectiveness. the results demonstrate that the proposed number of key points of micro - doppler signature can precisely represent the indoor human limb node motion characteristics, and substantially improve the generalization capability of the existing methods for different testers.
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arxiv:2408.12077
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the deadly triad refers to the instability of a reinforcement learning algorithm when it employs off - policy learning, function approximation, and bootstrapping simultaneously. in this paper, we investigate the target network as a tool for breaking the deadly triad, providing theoretical support for the conventional wisdom that a target network stabilizes training. we first propose and analyze a novel target network update rule which augments the commonly used polyak - averaging style update with two projections. we then apply the target network and ridge regularization in several divergent algorithms and show their convergence to regularized td fixed points. those algorithms are off - policy with linear function approximation and bootstrapping, spanning both policy evaluation and control, as well as both discounted and average - reward settings. in particular, we provide the first convergent linear $ q $ - learning algorithms under nonrestrictive and changing behavior policies without bi - level optimization.
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arxiv:2101.08862
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##ge argues that science - fiction authors cannot write realistic post - singularity characters who surpass the human intellect, as the thoughts of such an intellect would be beyond the ability of humans to express. minsky ' s 1994 article says robots will " inherit the earth ", possibly with the use of nanotechnology, and proposes to think of robots as human " mind children ", drawing the analogy from moravec. the rhetorical effect of that analogy is that if humans are fine to pass the world to their biological children, they should be equally fine to pass it to robots, their " mind " children. as per minsky, ' we could design our " mind - children " to think a million times faster than we do. to such a being, half a minute might seem as long as one of our years, and each hour as long as an entire human lifetime. ' the feature of the singularity present in minsky is the development of superhuman artificial intelligence ( " million times faster " ), but there is no talk of sudden intelligence explosion, self - improving thinking machines or unpredictability beyond any specific event and the word " singularity " is not used. tipler ' s 1994 book the physics of immortality predicts a future where super – intelligent machines will build enormously powerful computers, people will be " emulated " in computers, life will reach every galaxy and people will achieve immortality when they reach omega point. there is no talk of vingean " singularity " or sudden intelligence explosion, but intelligence much greater than human is there, as well as immortality. in 1996, yudkowsky predicted a singularity by 2021. his version of singularity involves intelligence explosion : once ais are doing the research to improve themselves, speed doubles after 2 years, then 1 one year, then after 6 months, then after 3 months, then after 1. 5 months, and after more iterations, the " singularity " is reached. this construction implies that the speed reaches infinity in finite time. in 2000, bill joy, a prominent technologist and a co - founder of sun microsystems, voiced concern over the potential dangers of robotics, genetic engineering, and nanotechnology. in 2005, kurzweil published the singularity is near. kurzweil ' s publicity campaign included an appearance on the daily show with jon stewart. from 2006 to 2012, an annual singularity summit conference was organized by machine intelligence research institute, founded by eliezer yudkowsky. in 2007, yud
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https://en.wikipedia.org/wiki/Technological_singularity
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the time dependent cluster approximation called the path probability method ( ppm ) is applied to a pseudo - spin ising hamiltonian of the slater - takagi model for kh2po4 - type hydrogen - bonded ferroelectrics in order to calculate the homogeneous dynamical susceptibility above and below the ferroelectric transition temperature. above the transition temperature all the calculations are carried out analytically in the cactus approximation of the ppm. below the transition temperature the dynamical susceptibility is also calculated accurately since the analytical solution of spontaneous polarization in the ferroelectric phase can be utilized. when the temperature is approached from both sides of the transition temperature, only one of relaxation times shows a critical slowing down and makes a main contribution to the dynamical susceptibility. the discrepancy from slater model ( ice - rule limit ) is discussed in comparison with some experimental data.
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arxiv:cond-mat/0011490
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we investigate the rotating quark matter in the three - flavor nambu and jona - lasinio ( njl ) model. the chiral condensation, spin polarization and number susceptibility of the light and strange quarks are carefully studied at finite temperature without or with finite chemical potential in this model. we find that the rotation suppresses the chiral condensation and enhances the first - order quark spin polarization, however for the second - order quark spin polarization and quark number susceptibility the effect is complicated and interesting. when extending to the situation with finite chemical potential, we find the angular velocity also plays a crucial role, at small angular velocity the chemical potential enhances the susceptibility, however in the middle region of angular velocity the effect of the chemical potential is suppressed by the angular velocity and susceptibility can be changed considerably, it can be observed that at very low temperature in the presence of quark chemical potential the quark number susceptibility has two maxima with increasing angular velocity. furthermore, it is found that at sufficiently large angular velocity the contributions played by light quark and strange quark to these phenomena are almost equal. we also explored the phase diagram in the $ t $ - $ \ omega $ plane, we observe that there exist first order phase transitions for the rotating system and the first order phase transition lines move toward a higher temperature for decreasing angular velocity. it is also found that the different chemical potentials change the boundary of phase diagram, and that a larger chemical potential shifts down the critical temperature. we expect these studies to be used to understand the chiral symmetry breaking and restoration as well as probe the qcd phase transition.
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arxiv:2104.14382
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in this work, we propose and numerically investigate a two - dimensional microlaser based on the concept of bound states in the continuum ( bic ). the device consists of a thin gain layer ( rhodamine 6g dye - doped silica ) sandwiched between two high - contrast - grating layers. the structure supports various bic modes upon a proper choice of topological parameters ; in particular it supports a high - q quasi - bic mode when partially breaking a bound state in the continuum at $ \ gamma $ point. the optically - pumped gain medium provides sufficient optical gain to compensate the quasi - bic mode losses, enabling lasing with ultra - low pump threshold ( fluence of 17 $ \ mu $ j / cm $ ^ 2 $ ) and very narrow optical linewidth in the visible range. this innovative device displays distinguished sensing performance for gas detection, and the emission wavelength sensitively shifts to the longer wavelength with the changing of environment refractive index ( in order of $ 5 \ times 10 ^ { - 4 } $ ). the achieved bulk sensitivity is 221 nm / riu with a high signal to noise ratio, and a record - high figure of merit reaches to 4420 riu $ ^ { - 1 } $. this ultracompact and low threshold quasi - bic laser facilitated by the ultra - narrow resonance can serve as formidable candidate for on - chip gas sensor.
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arxiv:2105.08885
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this report summarizes the discussions in the session 1 and session 3 groups which met to discuss the questions : ` ` what physical processes drive the multiphase interstellar medium in the local bubble? ' ', and ` ` what are the energy and pressure balances in the local bubble? ' ' most of our understanding of the local bubble has come from soft x - ray observations, but recent appreciation of the importance of solar wind charge exchange ( swcx ) reactions has shown that the heliosphere produces some fraction of the soft x - rays that were previously ascribed to the local bubble. some astronomers suggest that the swcx x - rays rather than local bubble emission could explain most of the locally produced x - rays. our discussions, therefore, also included a debate concerning the local bubble ' s existence.
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arxiv:0804.2444
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despite the growing advancements in automatic speech recognition ( asr ) models, the development of robust models for underrepresented languages, such as nepali, remains a challenge. this research focuses on making an exhaustive and generalized dataset followed by fine - tuning openai ' s whisper models of different sizes to improve transcription ( speech - to - text ) accuracy for the nepali language. we leverage publicly available asr datasets and self - recorded custom datasets with a diverse range of accents, dialects, and speaking styles further enriched through augmentation. our experimental results demonstrate that fine - tuning whisper models on our curated custom dataset substantially reduces the word error rate ( wer ) across all model sizes attributed to larger data variations in terms of speaker ' s age, gender, and sentiment, acoustic environment, dialect, denser audio segments ( 15 - 30 seconds ) that are more compatible with whisper ' s input, and manual curation of audios and transcriptions. notably, our approach outperforms whisper ' s baseline models trained on fleur ' s dataset, achieving wer reductions of up to 36. 2 % on the small and 23. 8 % on medium models. furthermore, we show that data augmentation plays a significant role in enhancing model robustness. our approach underlines the importance of dataset quality, variation, and augmentation in the adaptation of state - of - the - art models to underrepresented languages for developing accurate asr systems.
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arxiv:2411.12587
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uv observations of some massive globular clusters uncovered a significant population of very hot stars below the hot end of the horizontal branch ( hb ), the so - called blue hook stars. this feature might be explained either as results of the late hot flasher scenario where stars experience the helium flash while on the white dwarf cooling curve or by the progeny of the helium - enriched sub - population recently postulated to exist in some clusters. moderately high resolution spectra of stars at the hot end of the blue hb in omega cen were analysed for atmospheric parameters and abundances using lte and non - lte model atmospheres. in the temperature range 30, 000k to 50, 000k we find that 35 % of our stars are helium - poor ( log ( n _ he / n _ h ) < - 2 ), 51 % have solar helium abundance within a factor of 3 ( - 1. 5 < = log ( n _ he / n _ h ) < = - 0. 5 ) and 14 % are helium - rich ( log ( n _ he / n _ h ) > - 0. 4 ). we also find carbon enrichment in step with helium enrichment, with a maximum carbon enrichment of 3 % by mass. at least 14 % of the hottest hb stars in omega cen show helium abundances well above the highest predictions from the helium enrichment scenario ( y = 0. 42 corresponding to log ( n _ he / n _ h ) ~ - 0. 74 ). in addition, the most helium - rich stars show strong carbon enrichment as predicted by the late hot flasher scenario. we conclude that the helium - rich hb stars in omega cen cannot be explained solely by the helium - enrichment scenario invoked to explain the blue main sequence. ( abridged )
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arxiv:0709.2839
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in the paper i study properties of random polynomials with respect to a general system of functions. some lower bounds for the mathematical expectation of the uniform and recently introduced integral - uniform norms of random polynomials are established. { \ sc key words and phrases : } random polynomial, estimates for maximum of random process, integral - uniform norm.
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arxiv:math/0210341
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the x - ray bright z = 0. 116 quasar pks 2155 - 304 is frequently observed as a chandra calibration source, with a total of 483 ksec of low energy transmission grating ( letg ) exposure time accumulated through may 2006. highly - ionized metal absorption lines, including numerous lines at z = 0 and a putative oviii k - alpha line at z = 0. 055, have been reported in past chandra studies of this source. using all available chandra letg spectra and analysis techniques developed for such z = 0 x - ray absorption along other sightlines, we revisit these previous detections. we detect 4 absorption lines at > 3 \ sigma significance ( ovii k - alpha / beta, oviii k - alpha, and neix k - alpha ), with ovii k - alpha being a 7. 3 \ sigma detection. the 1 \ sigma ranges of z = 0 ovii column density and doppler parameter are consistent with those derived for mrk 421 and within 2 \ sigma of the mrk 279 absorption. temperatures and densities inferred from the relative ovii and other ionic column densities are found to be consistent with either the local warm - hot intergalactic medium or a galactic corona. unlike the local x - ray absorbers seen in other sightlines, a link with the low - or high - velocity far - ultraviolet ovi absorption lines cannot be ruled out. the z = 0. 055 oviii absorption reported by fang et al. is seen with 3. 5 \ sigma confidence in the acis / letg spectrum, but no other absorption lines are found at the same redshift.
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arxiv:astro-ph/0611583
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in this paper we introduce a variant of weight modules for certain conformal vertex superalgebras as an appropriate framework of the $ \ mathcal { n } = 2 $ supersymmetric coset construction. we call them weight - wise admissible modules. motivated by the work of feigin - semikhatov - tipunin, we give ( block - wise ) categorical equivalences between the categories of weight - wise admissible modules over $ \ widehat { \ mathfrak { sl } } _ { 2 } $ and the $ \ mathcal { n } = 2 $ superconformal algebra, induced by the coset construction. as an application, we obtain some character formulae of modules over the $ \ mathcal { n } = 2 $ superconformal algebra.
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arxiv:1605.02343
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the document describes a numerical algorithm to simulate plasmas and fluids in the 3 dimensional space by the euler method, in which the spatial meshes are fixed to the space. the plasmas and fluids move through the spacial euler mesh boundary. the euler method can represent a large deformation of the plasmas and fluids. on the other hand, when the plasmas or fluids are compressed to a high density, the spatial resolution should be ensured to describe the density change precisely. the present 3d euler code is developed to simulate a nuclear fusion fuel ignition and burning. therefore, the 3d euler code includes the dt fuel reactions, the alpha particle diffusion, the alpha particle deposition to heat the dt fuel and the dt fuel depletion by the dt reactions, as well as the thermal energy diffusion based on the three - temperature compressible fluid model.
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arxiv:2004.03810
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the fractal dimension of a surface allows its degree of roughness to be characterized quantitatively. however, limited effort is attempted to calculate the fractal dimension of surfaces computed from precisely known atomic coordinates from computational biomolecular and nanomaterial studies. this work proposes methods to estimate the fractal dimension of the surface of any 3d object composed of spheres, by representing the surface as either a voxelized point cloud or a mathematically exact surface, and computing its box - counting dimension. sphractal is published as a python package that provides these functionalities, and its utility is demonstrated on a set of simulated palladium nanoparticle data.
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arxiv:2401.11737
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in this paper we study in detail some spectral properties of the magnetic discrete laplacian. we identify its form - domain, characterize the absence of essential spectrum and provide the asymptotic eigenvalue distribution.
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arxiv:1106.0658
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reproducing kernel hilbert spaces ( rkhss ) are very important function spaces, playing an important role in machine learning, statistics, numerical analysis and pure mathematics. since lipschitz and h \ " older continuity are important regularity properties, with many applications in interpolation, approximation and optimization problems, in this work we investigate these continuity notion in rkhss. we provide several sufficient conditions as well as an in depth investigation of reproducing kernels inducing prescribed lipschitz or h \ " older continuity. apart from new results, we also collect related known results from the literature, making the present work also a convenient reference on this topic.
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arxiv:2310.18078
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we develop and experimentally verify a theory of type - ii spontaneous parametric down - conversion ( spdc ) in media with inhomogeneous distributions of second - order nonlinearity. as a special case, we explore interference effects from spdc generated in a cascade of two bulk crystals separated by an air gap. the polarization quantum - interference pattern is found to vary strongly with the spacing between the two crystals. this is found to be a cooperative effect due to two mechanisms : the chromatic dispersion of the medium separating the crystals and spatiotemporal effects which arise from the inclusion of transverse wave vectors. these effects provide two concomitant avenues for controlling the quantum state generated in spdc. we expect these results to be of interest for the development of quantum technologies and the generation of spdc in periodically varying nonlinear materials.
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arxiv:quant-ph/0112140
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we explore the possibilities of reaching the characterization of eigenfunction of laplacian as a degenerate case of the inverse paley - wiener theorem ( characterizing functions whose fourier transform is supported on a compact annulus ) for the riemannian symmetric spaces of noncompact type. most distinguished prototypes of these spaces are the hyperbolic spaces. the statement and the proof of the main result work mutatis - mutandis for a number of spaces including euclidean spaces and damek - ricci spaces.
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arxiv:1406.3964
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models of the cortico - basal ganglia network and volume conductor models of the brain can provide insight into the mechanisms of action of deep brain stimulation ( dbs ). in this study, the coupling of a network model, under parkinsonian conditions, to the extracellular field distribution obtained from a three dimensional finite element model of a rodent ' s brain during dbs is presented. this coupled model is used to investigate the influence of uncertainty in the electrical properties of brain tissue and encapsulation tissue, formed around the electrode after implantation, on the suppression of oscillatory neural activity during dbs. the resulting uncertainty in this effect of dbs on the network activity is quantified using a computationally efficient and non - intrusive stochastic approach based on the generalized polynomial chaos. the results suggest that variations in the electrical properties of brain tissue may have a substantial influence on the level of suppression of oscillatory activity during dbs. applying a global sensitivity analysis on the suppression of the simulated oscillatory activity showed that the influence of uncertainty in the electrical properties of the encapsulation tissue had only a minor influence, in agreement with previous experimental and computational studies investigating the mechanisms of current - controlled dbs in the literature.
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arxiv:1705.10496
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this talk presents work concepts and results for the determination of the fine structure constant $ \ alpha $ at the $ z _ 0 $ mass resonance. the problem consisting of the break - down of global duality for singular integral weights is circumvented by using a polynomial fit which mimics this weight function. this method is conservative in the sense that it is mostly independent of special assumptions. in this context the difference between local and global duality is explained.
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arxiv:hep-ph/9905373
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federated learning ( fl ) offers a decentralized training approach for machine learning models, prioritizing data privacy. however, the inherent heterogeneity in fl networks, arising from variations in data distribution, size, and device capabilities, poses challenges in user federation. recognizing this, personalized federated learning ( pfl ) emphasizes tailoring learning processes to individual data profiles. in this paper, we address the complexity of clustering users in pfl, especially in dynamic networks, by introducing a dynamic upper confidence bound ( ducb ) algorithm inspired by the multi - armed bandit ( mab ) approach. the ducb algorithm ensures that new users can effectively find the best cluster for their data distribution by balancing exploration and exploitation. the performance of our algorithm is evaluated in various cases, showing its effectiveness in handling dynamic federated learning scenarios.
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arxiv:2310.19069
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global routing has been a historically challenging problem in electronic circuit design, where the challenge is to connect a large and arbitrary number of circuit components with wires without violating the design rules for the printed circuit boards or integrated circuits. similar routing problems also exist in the design of complex hydraulic systems, pipe systems and logistic networks. existing solutions typically consist of greedy algorithms and hard - coded heuristics. as such, existing approaches suffer from a lack of model flexibility and non - optimum solutions. as an alternative approach, this work presents a deep reinforcement learning method for solving the global routing problem in a simulated environment. at the heart of the proposed method is deep reinforcement learning that enables an agent to produce an optimal policy for routing based on the variety of problems it is presented with leveraging the conjoint optimization mechanism of deep reinforcement learning. conjoint optimization mechanism is explained and demonstrated in details ; the best network structure and the parameters of the learned model are explored. based on the fine - tuned model, routing solutions and rewards are presented and analyzed. the results indicate that the approach can outperform the benchmark method of a sequential a * method, suggesting a promising potential for deep reinforcement learning for global routing and other routing or path planning problems in general. another major contribution of this work is the development of a global routing problem sets generator with the ability to generate parameterized global routing problem sets with different size and constraints, enabling evaluation of different routing algorithms and the generation of training datasets for future data - driven routing approaches.
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arxiv:1906.08809
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one can argue that on flat space $ \ mathbb { r } ^ d $ the weyl quantization is the most natural choice and that it has the best properties ( e. g. symplectic covariance, real symbols correspond to hermitian operators ). on a generic manifold, there is no distinguished quantization, and a quantization is typically defined chart - wise. here we introduce a quantization that, we believe, has the best properties for studying natural operators on pseudo - riemannian manifolds. it is a generalization of the weyl quantization - we call it the balanced geodesic weyl quantization. among other things, we prove that it maps square integrable symbols to hilbert - schmidt operators, and that even ( resp. odd ) polynomials are mapped to even ( resp. odd ) differential operators. we also present a formula for the corresponding star product and give its asymptotic expansion up to the 4th order in planck ' s constant.
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arxiv:1806.01572
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semantic communication has emerged as a transformative paradigm in next - generation communication systems, leveraging advanced artificial intelligence ( ai ) models to extract and transmit semantic representations for efficient information exchange. nevertheless, the presence of unpredictable semantic noise, such as ambiguity and distortions in transmitted representations, often undermines the reliability of received information. conventional approaches primarily adopt adversarial training with noise injection to mitigate the adverse effects of noise. however, such methods exhibit limited adaptability to varying noise levels and impose additional computational overhead during model training. to address these challenges, this paper proposes noise - resilient \ textbf { se } mantic communication with \ textbf { hi } gh - and - \ textbf { lo } w frequency decomposition ( se - hilo ) for image transmission. the proposed se - hilo incorporates a finite scalar quantization ( fsq ) based noise - resilient module, which bypasses adversarial training by enforcing encoded representations within predefined spaces to enhance noise resilience. while fsq improves robustness, it compromise representational diversity. to alleviate this trade - off, we adopt a transformer - based high - and - low frequency decomposition module that decouples image representations into high - and - low frequency components, mapping them into separate fsq representation spaces to preserve representational diversity. extensive experiments demonstrate that se - hilo achieves superior noise resilience and ensures accurate semantic communication across diverse noise environments.
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arxiv:2503.06883
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we prove an asymptotically sharp version of the bourgain - clozel - kahane and cohn - gon \ c { c } alves sign uncertainty principles for polynomials of sublinear degree times a gaussian, as the dimension tends to infinity. in particular, we show that polynomials whose degree is sublinear in the dimension cannot improve asymptotically on those of degree at most three. this question arises naturally in the study of both linear programming bounds for sphere packing and the spinless modular bootstrap bound for free bosons.
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arxiv:2210.01684
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a classic result of delsarte connects the strength ( as orthogonal array ) of a linear code with the minimum weight of its dual : the former is one less than the latter. we show that delsarte ' s observation extends to codes over arbitrary finite rings. since the paper of hammons \ emph { et al. }, there is a lot of interest in codes over rings, especially in codes over $ z _ 4 $ and their ( usually non - linear ) binary gray map images. we show that delsarte ' s observation extends to codes over arbitrary finite commutative rings with identity. also, we show that the strength of the gray map image of a $ z _ 4 $ code is one less than the minimum lee weight of its gray map image.
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arxiv:1510.01509
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a redshift survey has been carried out in the region of the hubble deep field north using the low resolution imaging spectrograph at the keck observatory. the resulting redshift catalog, which contains 671 entries, is a compendium of our own data together with published lris / keck data. it is more than 92 % complete for objects, irrespective of morphology, to $ r = 24 $ mag in the hdf itself and to $ r = 23 $ mag in the flanking fields within a diameter of 8 arcmin centered on the hdf, an unusually high completion for a magnitude limited survey performed with a large telescope. a median redshift $ z = 1. 0 $ is reached at $ r \ sim 23. 8 $. strong peaks in the redshift distribution, which arise when a group or poor cluster of galaxies intersect the area surveyed, can be identified to $ z \ sim 1. 2 $ in this dataset. more than 68 % of the galaxies are members of these redshift peaks. in a few cases, closely spaced peaks in $ z $ can be resolved into separate groups of galaxies that can be distinguished in both velocity and location on the sky. the radial separation of these peaks in the pencil - beam survey is consistent with a characteristic length scale for the their separation of $ \ approx $ 70 mpc in our adopted cosmology ( $ h = 0. 6, \ omega _ m = 0. 3 $, $ \ lambda = 0 $ ). strong galaxy clustering is in evidence at all epochs back to $ z \ le 1. 1 $. ( abstract abridged )
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arxiv:astro-ph/9912048
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we evaluate chemical patent word embeddings against known biomedical embeddings and show that they outperform the latter extrinsically and intrinsically. we also show that using contextualized embeddings can induce predictive models of reasonable performance for this domain over a relatively small gold standard.
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arxiv:2010.12912
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click - through rate ( ctr ) prediction is a pivotal task in product and content recommendation, where learning effective feature embeddings is of great significance. however, traditional methods typically learn fixed feature representations without dynamically refining feature representations according to the context information, leading to suboptimal performance. some recent approaches attempt to address this issue by learning bit - wise weights or augmented embeddings for feature representations, but suffer from uninformative or redundant features in the context. to tackle this problem, inspired by the global workspace theory in conscious processing, which posits that only a specific subset of the product features are pertinent while the rest can be noisy and even detrimental to human - click behaviors, we propose a ctr model that enables dynamic embedding learning with truncated conscious attention for ctr prediction, termed delta. delta contains two key components : ( i ) conscious truncation module ( ctm ), which utilizes curriculum learning to apply adaptive truncation on attention weights to select the most critical feature in the context ; ( ii ) explicit embedding optimization ( eeo ), which applies an auxiliary task during training that directly and independently propagates the gradient from the loss layer to the embedding layer, thereby optimizing the embedding explicitly via linear feature crossing. extensive experiments on five challenging ctr datasets demonstrate that delta achieves new state - of - art performance among current ctr methods.
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arxiv:2305.04891
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the overall performance of the development of computing systems has been engrossed on enhancing demand from the client and enterprise domains. but, the intake of ever - increasing energy for computing systems has commenced to bound in increasing overall performance due to heavy electric payments and carbon dioxide emission. the growth in power consumption of server is increased continuously, and many researchers proposed, if this pattern repeats continuously, then the power consumption cost of a server over its lifespan would be higher than its hardware prices. the power intake troubles more for clusters, grids, and clouds, which encompass numerous thousand heterogeneous servers. continuous efforts have been done to reduce the electricity intake of these massive - scale infrastructures. to identify the challenges and required future enhancements in the field of efficient energy consumption in cloud computing, it is necessary to synthesize and categorize the research and development done so far. in this paper, the authors discuss the reasons and problems associated with huge energy consumption by cloud data centres and prepare a taxonomy of huge energy consumption problems and its related solutions. the authors cover all aspects of energy consumption by cloud data centers and analyze many research papers to find the better solution for efficient energy consumption. this work gives an overall information regarding energy - consumption problems of cloud data centres and energy - efficient solutions for this problem. the paper is concluded with a conversation of future enhancement and development in energy - efficient methods in cloud computing
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arxiv:1810.07458
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the ground and low - lying collective states of a rotating system of $ n = 3 $ bosons harmonically confined in quasi - two - dimension and interacting via repulsive finite - range gaussian potential is studied in weakly to moderately interacting regime. the $ n $ - body hamiltonian matrix is diagonalized in subspaces of quantized total angular momenta $ 0 \ le l \ le 4n $ to obtain the ground and low - lying eigenstates. our numerical results show that breathing modes with $ n $ - body eigenenergy spacing of $ 2 \ hbar \ omega _ { \ perp } $, known to exist in strictly 2d system with zero - range ( $ \ delta $ - function ) interaction potential, may as well exist in quasi - 2d system with finite - range gaussian interaction potential. to gain an insight into the many - body states, the von neumann entropy is calculated as a measure of quantum correlation and the conditional probability distribution is analyzed for the internal structure of the eigenstates. in the rapidly rotating regime the ground state in angular momentum subspaces $ l = \ frac { q } { 2 } n \ left ( n - 1 \ right ) $ with $ q = 2, 4 $ is found to exhibit the anticorrelation structure suggesting that it may variationally be described by a bose - laughlin like state. we further observe that the first breathing mode exhibits features similar to the bose - laughlin state in having eigenenergy, von neumann entropy and internal structure independent of interaction for the three - boson system considered here. on the contrary, for eigenstates lying between the bose - laughlin like ground state and the first breathing mode, values of eigenenergy, von neumann entropy and internal structure are found to vary with interaction.
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arxiv:1508.05030
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the generators $ ( j _ { \ pm }, j _ 0 ) $ of the algebra $ u _ q ( sl ( 2 ) ) $ is our starting point. an invertible nonlinear map involving, apart from q, a second arbitrary complex parameter h, defines a triplet $ ( { \ hat x }, { \ hat y }, { \ hat h } ) $. the latter set forms a closed algebra under commutation relations. the nonlinear algebra $ u _ { q, h } ( sl ( 2 ) ) $, thus generated, has two different limits. for $ q \ to 1 $, the jordanian h - deformation $ u _ { h } ( sl ( 2 ) ) $ is obtained. for $ h \ to 0 $, the q - deformed algebra $ u _ { q } ( sl ( 2 ) ) $ is reproduced. from the nonlinear map, the irreducible representations of the doubly - deformed algebra $ u _ { q, h } ( sl ( 2 ) ) $ may be directly and explicitly obtained form the known representations of the algebra $ u _ q ( sl ( 2 ) ) $. here we consider only generic values of q.
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arxiv:q-alg/9612028
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the majority of existing lidar odometry solutions are based on simple geometric features such as points, lines or planes which cannot fully reflect the characteristics of surrounding environments. in this study, we propose a novel lidar odometry which effectively utilizes the overall exterior characteristics of environmental landmarks. the vehicle pose estimation is accomplished by means of two sequential pose estimation stages, namely, horizontal pose estimation and vertical pose estimation. to achieve effective landmark registration, a comprehensive index is proposed to evaluate the level of similarity between landmarks. this index takes into account two crucial aspects of landmarks, namely, dimension and shape in evaluating their similarity. to assess the performance of the proposed algorithm, we utilize the widely recognized kitti dataset as well as experimental data collected by an unmanned ground vehicle platform. both graphical and numerical results indicate that our algorithm outperforms leading lidar odometry solutions in terms of positioning accuracy.
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arxiv:2312.16787
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we consider a finite - time stochastic drift control problem with the assumption that the control is bounded and the system is controlled until the state process leaves the half - line. assuming general conditions, it is proved that the resulting parabolic hamilton - jacobi - bellman equation has a classical solution. in fact, we consider an even more general family of semilinear equations, which might be helpful in solving other control or game problems. not only is the existence result proved, but also a recursive procedure for finding a solution resulting from a fixed - point argument is provided. an application to the dividend optimization problem is presented.
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arxiv:2503.19648
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an efficient numerical code fp3d has been developed to calculate particle orbits and evaluate particle confinement in 3d magnetic fields including stellarators and tokamaks with 3d fields. the magnetic field is either calculated from coils directly or obtained from equilibrium codes. fp3d has been verified with the 3d equilibrium code vmec ( s. p. hirshman, phys. fluids 26, 3553 ( 1983 ) ) for magnetic field calculation and with the drift - kinetic code sfincs ( m. landreman, physics of plasmas 21 ( 4 ) ( 2014 ) ) for neoclassical transport. the code has been applied successfully to the ncsx stellarator ( b. nelson, fusion engineering and design 66 ( 2003 ) ) for the calculation of neoclassical transport coefficient with the 3d magnetic field obtained directly from coils. fp3d is also used to calculate ripple losses in the tokamak east ( w. yuanxi, plasma science technology 8 ( 3 ) ( 2006 ) ).
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arxiv:2310.08188
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in the field of resource - constrained robots and the need for effective place recognition in multi - robotic systems, this article introduces recnet, a novel approach that concurrently addresses both challenges. the core of recnet ' s methodology involves a transformative process : it projects 3d point clouds into range images, compresses them using an encoder - decoder framework, and subsequently reconstructs the range image, restoring the original point cloud. additionally, recnet utilizes the latent vector extracted from this process for efficient place recognition tasks. this approach not only achieves comparable place recognition results but also maintains a compact representation, suitable for sharing among robots to reconstruct their collective maps. the evaluation of recnet encompasses an array of metrics, including place recognition performance, the structural similarity of the reconstructed point clouds, and the bandwidth transmission advantages, derived from sharing only the latent vectors. our proposed approach is assessed using both a publicly available dataset and field experiments $ ^ 1 $, confirming its efficacy and potential for real - world applications.
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arxiv:2402.02192
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we present a charge and self - energy self - consistent computational scheme for correlated systems based on the korringa - kohn - rostoker ( kkr ) multiple scattering theory with the many - body effects described by the means of dynamical mean field theory ( dmft ). the corresponding local multi - orbital and energy dependent self - energy is included into the set of radial differential equations for the single - site wave functions. the kkr green ' s function is written in terms of the multiple scattering path operator, the later one being evaluated using the single - site solution for the $ t $ - matrix that in turn is determined by the wave functions. an appealing feature of this approach is that it allows to consider local quantum and disorder fluctuations on the same footing. within the coherent potential approximation ( cpa ) the correlated atoms are placed into a combined effective medium determined by the dynamical mean field theory ( dmft ) self - consistency condition. results of corresponding calculations for pure fe, ni and fe $ _ { x } $ ni $ _ { 1 - x } $ alloys are presented.
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arxiv:cond-mat/0504760
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the scaling properties of the maximal height of a growing self - affine surface with a lateral extent $ l $ are considered. in the late - time regime its value measured relative to the evolving average height scales like the roughness : $ h ^ { * } _ { l } \ sim l ^ { \ alpha } $. for large values its distribution obeys $ \ log { p ( h ^ { * } _ { l } ) } \ sim - a ( { h ^ { * } _ { l } } / l ^ { \ alpha } ) ^ { a } $, charaterized by the exponential - tail exponent $ a $. in the early - time regime where the roughness grows as $ t ^ { \ beta } $, we find $ h ^ { * } _ { l } \ sim t ^ { \ beta } [ \ ln { l } - ( { \ beta \ over \ alpha } ) \ ln { t } + c ] ^ { 1 / b } $ where either $ b = a $ or $ b $ is the corresponding exponent of the velocity distribution. these properties are derived from scaling and extreme - values arguments. they are corroborated by numerical simulations and supported by exact results for surfaces in 1d with the asymptotic behavior of a brownian path.
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arxiv:cond-mat/0105176
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we demonstrate the feasibility of framing a classically learned deep neural network as an energy based model that can be processed on a one - step quantum annealer in order to exploit fast sampling times. we propose approaches to overcome two hurdles for high resolution image classification on a quantum processing unit ( qpu ) : the required number and binary nature of the model states. with this novel method we successfully transfer a convolutional neural network to the qpu and show the potential for classification speedup of at least one order of magnitude.
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arxiv:2107.08710
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we apply implicit regularization in the calculation of the one - loop graviton and gravitino corrections to the anomalous magnetic moment of the lepton in unbroken supergravity, which is known to be an important test for any regularization method. we find a null result as it is expected from supersymmetry. we compare our results with the ones obtained by using differential regularization and dimensional reduction, which are known to preserve supersymmetry at one - loop order.
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arxiv:hep-ph/0607052
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the gluex experiment is located in experimental hall d at jefferson lab ( jlab ) and provides a unique capability to search for hybrid mesons in high - energy photoproduction, utilizing a ~ 9 gev linearly polarized photon beam. the initial, low - intensity phase of gluex was recently completed and a high - intensity phase has begun in 2020 which includes an upgraded kaon identification system, known as the dirc ( detection of internally reflected cherenkov light ), utilizing components from the decommissioned babar dirc. the identification of kaon final states will significantly enhance the gluex physics program, to aid in inferring the quark flavor content of conventional ( and potentially hybrid ) mesons. in these proceedings we describe the installation of the gluex dirc and the analysis of initial commissioning data
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arxiv:2002.07990
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pollution plume monitoring using autonomous vehicles is important due to the adverse effect of pollution plumes on the environment and associated monetary losses. using the advection - diffusion plume dispersion model, we present a control law design to track dynamic concentration level curves. we also present a gradient and divergence estimation method to enable this control law from concentration measurement only. we then present the field testing results of the control law to track concentration level curves in a plume generated using rhodamine dye as a pollution surrogate in a near - shore marine environment. these plumes are then autonomously tracked using an unmanned surface vessel equipped with fluorometer sensors. field experimental results are shown to evaluate the performance of the controller, and complexities of field experiments in real - world marine environments are discussed in the paper.
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arxiv:1804.08669
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we consider the asymptotic behavior of a family of gradient methods, which include the steepest descent and minimal gradient methods as special instances. it is proved that each method in the family will asymptotically zigzag between two directions. asymptotic convergence results of the objective value, gradient norm, and stepsize are presented as well. to accelerate the family of gradient methods, we further exploit spectral properties of stepsizes to break the zigzagging pattern. in particular, a new stepsize is derived by imposing finite termination on minimizing two - dimensional strictly convex quadratic function. it is shown that, for the general quadratic function, the proposed stepsize asymptotically converges to the reciprocal of the largest eigenvalue of the hessian. furthermore, based on this spectral property, we propose a periodic gradient method by incorporating the barzilai - borwein method. numerical comparisons with some recent successful gradient methods show that our new method is very promising.
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arxiv:1908.07111
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solid - density plasmas driven by intense x - ray free - electron laser ( xfel ) radiation are seeded by sources of non - thermal photoelectrons and auger electrons that ionize and heat the target via collisions. simulation codes that are commonly used to model such plasmas, such as collisional - radiative ( cr ) codes, typically assume a maxwellian distribution and thus instantaneous thermalization of the source electrons. in this study, we present a detailed description and initial applications of a collisional particle - in - cell code, picls, that has been extended with a self - consistent radiation transport model and monte - carlo models for photoionization and kll auger ionization, enabling the fully kinetic simulation of xfel - driven plasmas. the code is used to simulate two experiments previously performed at the linac coherent light source investigating xfel - driven solid - density al plasmas. it is shown that picls - simulated pulse transmissions using the ecker - kr \ " oll continuum - lowering model agree much better with measurements than do simulations using the stewart - pyatt model. good quantitative agreement is also found between the time - dependent picls results and those of analogous simulations by the cr code scfly, which was used in the analysis of the experiments to accurately reproduce the observed k { \ alpha } emissions and pulse transmissions. finally, it is shown that the effects of the non - thermal electrons are negligible for the conditions of the particular experiments under investigation.
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arxiv:1704.01202
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unsupervised hashing is important for indexing huge image or video collections without having expensive annotations available. hashing aims to learn short binary codes for compact storage and efficient semantic retrieval. we propose an unsupervised deep hashing layer called bi - half net that maximizes entropy of the binary codes. entropy is maximal when both possible values of the bit are uniformly ( half - half ) distributed. to maximize bit entropy, we do not add a term to the loss function as this is difficult to optimize and tune. instead, we design a new parameter - free network layer to explicitly force continuous image features to approximate the optimal half - half bit distribution. this layer is shown to minimize a penalized term of the wasserstein distance between the learned continuous image features and the optimal half - half bit distribution. experimental results on the image datasets flickr25k, nus - wide, cifar - 10, mscoco, mnist and the video datasets ucf - 101 and hmdb - 51 show that our approach leads to compact codes and compares favorably to the current state - of - the - art.
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arxiv:2012.12334
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nano - protrusion ( np ) on metal surface and its inevitable contamination layer under high electric field is often considered as the primary precursor that leads to vacuum breakdown, which plays an extremely detrimental effect for high energy physics equipment and many other devices. yet, the np growth has never been experimentally observed. here, we conduct field emission ( fe ) measurements along with in - situ transmission electron microscopy ( tem ) imaging of an amorphous - carbon ( a - c ) coated tungsten nanotip at various nanoscale vacuum gap distances. we find that under certain conditions, the fe current - voltage ( i - v ) curves switch abruptly into an enhanced - current state, implying the growth of an np. we then run field emission simulations, demonstrating that the temporary enhanced - current i - v is perfectly consistent with the hypothesis that a np has grown at the apex of the tip. this hypothesis is also confirmed by the repeatable in - situ observation of such a nano - protrusion and its continued growth during successive fe measurements in tem. we tentatively attribute this phenomenon to field - induced biased diffusion of surface a - c atoms, after performing a finite element analysis that excludes the alternative possibility of field - induced plastic deformation.
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arxiv:2403.11794
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in this paper, a modified eddington - inspired - born - infeld ( eibi ) theory with a pure trace term $ g _ { \ mu \ nu } r $ being added to the determinantal action is analysed from a cosmological point of view. it corresponds to the most general action constructed from a rank two tensor that contains up to first order terms in curvature. this term can equally be seen as a conformal factor multiplying the metric $ g _ { \ mu \ nu } $. this very interesting type of amendment has not been considered within the palatini formalism despite the large amount of works on the born - infeld - inspired theory of gravity. this model can provide smooth bouncing solutions which were not allowed in the eibi model for the same eibi coupling. most interestingly, for a radiation filled universe there are some regions of the parameter space that can naturally lead to a de sitter inflationary stage without the need of any exotic matter field. finally, in this model we discover a new type of cosmic " quasi - sudden " singularity, where the cosmic time derivative of the hubble rate becomes very large but finite at a finite cosmic time.
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arxiv:1507.00028
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currently, a major concern is the insufficient level of safety offered by commercial automated vehicles and / or services such self - driving vehicles, self - driving trucks, and robotaxis. unfortunately, stakeholders do not agree on definitions and characterizations of what is meant by safety of automated vehicles including how to measure it and how to design for it. this paper sheds some light into the answers to important questions about the safety of automated vehicles. in addition, we identify rigor as a significant missing requirement in the current literature, we also provide a discussion of rigor in the design, development, and commercialization of automated vehicles. furthermore, we discuss software tool requirements at the organizational level to support a rigorous approach for the analysis, design, and commercialization of automated vehicles. an alm tool, ewqims, is introduced emphasizing its rigorous features of its functional safety module that implements much of the iso 26262 standard.
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arxiv:2406.08350
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the goal of this note is to give an introduction to locally conformally symplectic and k \ " ahler geometry. in particular, sections 1 and 3 aim to provide the reader with enough mathematical background to appreciate this kind of geometry. the reference book for locally conformally k \ " ahler geometry is " locally conformal k \ " ahler geometry " by sorin dragomir and liviu ornea. many progresses in this field, however, were accomplished after the publication of this book, hence are not contained there. on the other hand, there is no book on locally conformally symplectic geometry and many recent advances lie scattered in the literature. sections 2 and 4 would like to demonstrate how these geometries can be used to give precise mathematical formulations to ideas deeply rooted in classical and modern physics.
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arxiv:1711.02440
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we present a generalization of luescher ' s relation between the finite - volume spectrum and scattering amplitudes to the case of three particles. we consider a relativistic scalar field theory in which the couplings are arbitrary aside from a z2 symmetry that removes vertices with an odd number of particles. the theory is assumed to have two - particle phase shifts that are bounded by \ pi / 2 in the regime of elastic scattering. we determine the spectrum of the finite - volume theory from the poles in the odd - particle - number finite - volume correlator, which we analyze to all orders in perturbation theory. we show that it depends on the infinite - volume two - to - two k - matrix as well as a nonstandard infinite - volume three - to - three k - matrix. a key feature of our result is the need to subtract physical singularities in the three - to - three amplitude and thus deal with a divergence - free quantity. this allows our initial, formal result to be truncated to a finite dimensional determinant equation. at present, the relation of the three - to - three k - matrix to the corresponding scattering amplitude is not known, although previous results in the non - relativistic limit suggest that such a relation exists.
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arxiv:1408.5933
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in this article we examine a generalized uncertainty principle which differs from the heisenberg uncertainty principle by terms linear and quadratic in particle momenta, as proposed by the authors in an earlier paper. we show that this affects all hamiltonians, and in particular those which describe low energy experiments. we discuss possible observational consequences. further, we also show that this indicates that space may be discrete at the fundamental level.
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arxiv:1001.2642
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in this work, the problem of localizing ground devices ( gds ) is studied comparing the performance of four range - free ( rf ) localization algorithms that use a mobile anchor ( ma ). all the investigated algorithms are based on the so - called heard / not - heard ( hnh ) method, which allows the gds to detect the ma at the border of their antenna communication radius. despite the simplicity of this method, its efficacy in terms of accuracy is poor because it relies on the antenna radius that continuously varies under different conditions. usually, the antenna radius declared by the manufacturer does not fully characterize the actual antenna radiation pattern. in this paper, the radiation pattern of the commercial decawave dwm1001 ultra - wide - band ( uwb ) antennas is observed in a real test - bed at different altitudes for collecting more information and insights on the antenna radius. the compared algorithms are then tested using both the observed and the manufacturer radii. the experimental accuracy is close to the expected theoretical one only when the antenna pattern is actually omnidirectional. however, typical antennas have strong pattern irregularities that decrease the accuracy. for improving the performance, we propose range - based ( rb ) variants of the compared algorithms in which, instead of using the observed or the manufacturer radii, the actual measured distances between the ma and the gd are used. the localization accuracy tremendously improves confirming that the knowledge of the exact antenna pattern is essential for any rf algorithm.
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arxiv:2102.05725
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we discuss a model of an economic community consisting of $ n $ interacting agents. the state of each agent at any time is characterized, in general, by a mixed strategy profile drawn from a space of $ s $ pure strategies. the community evolves as agents update their strategy profiles in response to payoffs received from other agents. the evolution equation is a generalization of the replicator equation. we argue that when $ n $ is sufficiently large and the payoff matrix elements satisfy suitable inequalities, the community evolves to retain the full diversity of available strategies even as individual agents specialize to pure strategies.
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arxiv:adap-org/9804004
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