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the possibility of tailoring the guidance properties of optical fibers along the same direction as the evolution of the optical field allows to explore new directions in nonlinear fiber optics. the new degree of freedom offered by axially - varying optical fibers enables to revisit well - established nonlinear phenomena, and even to discover novel short pulse nonlinear dynamics. here we study the impact of meter - scale longitudinal variations of group velocity dispersion on the propagation of bright solitons and on their associated dispersive waves. we show that the longitudinal tailoring of fiber properties allows to observe experimentally unique dispersive waves dynamics, such as the emission of cascaded, multiple or polychromatic dispersive waves. | arxiv:1710.04836 |
adversarial attacks often involve random perturbations of the inputs drawn from uniform or gaussian distributions, e. g., to initialize optimization - based white - box attacks or generate update directions in black - box attacks. these simple perturbations, however, could be sub - optimal as they are agnostic to the model being attacked. to improve the efficiency of these attacks, we propose output diversified sampling ( ods ), a novel sampling strategy that attempts to maximize diversity in the target model ' s outputs among the generated samples. while ods is a gradient - based strategy, the diversity offered by ods is transferable and can be helpful for both white - box and black - box attacks via surrogate models. empirically, we demonstrate that ods significantly improves the performance of existing white - box and black - box attacks. in particular, ods reduces the number of queries needed for state - of - the - art black - box attacks on imagenet by a factor of two. | arxiv:2003.06878 |
soap bubbles are simple, yet very unique and marvelous objects. they exhibit a number of interesting properties such as beautiful interference colors and the formation of minimal surfaces. various optical phenomena have been studied in soap films and bubbles, but so far they were not employed as optical cavities. here we demonstrate, that dye doped soap or smectic liquid crystal bubbles can support whispering gallery mode lasing, which is observed in the spectrum as hundreds of regularly spaced peaks, resembling a frequency comb. the lasing enabled the measurement of size changes as small as 10 nm in a millimeter - sized, $ \ sim $ 100 nm thick bubble. bubble lasers were used as extremely sensitive electric field sensors with a smallest measurable electric field of 110 vm $ ^ { - 1 } $ hz $ ^ { - 1 / 2 } $. they also enable the measurement of pressures up to a 100 bar with a resolution of 1. 5 pa, resulting in a dynamic range of almost $ 10 ^ 7 $. by connecting the bubble to a reservoir of air, almost arbitrarily low pressure changes can be measured while maintaining an outstanding dynamic range. the demonstrated soap bubble lasers are a very unique type of microcavities which are one of the best electric field and pressure microsensors to date and could in future also be employed to study thin films and cavity optomechanics. | arxiv:2306.14676 |
thermoreversible hydrogels are commonly prepared by cooling down to ambient temperature, aqueous polymer solutions first brought to a boil. the incubation time of the polymer solution at such a high temperature is traditionally kept to a minimum to minimize its impact on the subsequent gelation. here we study the effect of a prolonged heating of a 1. 5 \ % w / w agar solution at $ t = 80 ^ { \ circ } $ c, well above the gelling temperature. the incubation time $ \ mathcal { t } $ of the polysaccharide solution is varied from a few hours up to five days. we show that the agar solution ages as the result of both the hydrolysis and the intramolecular oxidation of the polysaccharides. as a consequence, both the viscosity and the ph of the solution decrease continuously during the incubation period. furthermore, samples withdrew at different incubation times are cooled down to form gels which structure and mechanical properties are systematically determined. cryo - microscopy and x - ray diffraction experiments reveal that agar gels formed from solutions of increasing incubation times, display a coarser microstructure composed of micron - sized foils which result from the condensation of the polysaccharides and contrast with the fibrous - like microstructure of gels prepared from a fresh agar solution. along with structural changes, a prolonged incubation time of the polymer solution at $ t = 80 ^ { \ circ } $ c leads to weaker agar gels of significantly lower shear elastic modulus. moreover, extensive macro - indentation experiments coupled to direct visualization show that increasing the incubation time of the agar solution up to a few days decreases the yield strain of the gel, while the rupture scenario turns continuously from brittle to ductile - like. our study suggests that the incubation time of agar solutions at high temperature could be used to tune the mechanical properties of agar - based gels. | arxiv:1603.00778 |
to validate the second - by - second dynamics of turbines in field experiments, it is necessary to accurately reconstruct the winds going into the turbine. current time - resolved inflow reconstruction techniques estimate wind behavior in unobserved regions using relatively simple spectral - based models of the atmosphere. here, we develop a technique for time - resolved inflow reconstruction that is rooted in a large - eddy simulation model of the atmosphere. our " large - eddy reconstruction " technique blends observations and atmospheric model information through a diffusion model machine learning algorithm, allowing us to generate probabilistic ensembles of reconstructions for a single 10 - min observational period. our generated inflows can be used directly by aeroelastic codes or as inflow boundary conditions in a large - eddy simulation. we verify the second - by - second reconstruction capability of our technique in three synthetic field campaigns, finding positive pearson correlation coefficient values ( 0. 20 > r > 0. 85 ) between ground - truth and reconstructed streamwise velocity, as well as smaller positive correlation coefficient values for unobserved fields ( spanwise velocity, vertical velocity, and temperature ). we validate our technique in three real - world case studies by driving large - eddy simulations with reconstructed inflows and comparing to independent inflow measurements. the reconstructions are visually similar to measurements, follow desired power spectra properties, and track second - by - second behavior ( 0. 25 > r > 0. 75 ). | arxiv:2410.14024 |
we present the yahoo flickr creative commons 100 million dataset ( yfcc100m ), the largest public multimedia collection that has ever been released. the dataset contains a total of 100 million media objects, of which approximately 99. 2 million are photos and 0. 8 million are videos, all of which carry a creative commons license. each media object in the dataset is represented by several pieces of metadata, e. g. flickr identifier, owner name, camera, title, tags, geo, media source. the collection provides a comprehensive snapshot of how photos and videos were taken, described, and shared over the years, from the inception of flickr in 2004 until early 2014. in this article we explain the rationale behind its creation, as well as the implications the dataset has for science, research, engineering, and development. we further present several new challenges in multimedia research that can now be expanded upon with our dataset. | arxiv:1503.01817 |
stewart shapiro, 2000. thinking about mathematics : the philosophy of mathematics. oxford university press. = = external links = = stanford encyclopedia of philosophy : " abstract objects " — by gideon rosen. wells, charles. " mathematical objects ". amof : the amazing mathematical object factory mathematical object exhibit | https://en.wikipedia.org/wiki/Mathematical_object |
the extreme ultraviolet imaging spectrometer ( eis ) on board hinode is the first solar telescope to obtain wide slit spectral images that can be used for detecting doppler flows in transition region and coronal lines on the sun and to relate them to their surrounding small scale dynamics. we select eis lines covering the temperature range 6x10 ^ 4 k to 2x10 ^ 6 k that give spectrally pure images of the sun with the 40 arcsec slit. in these images doppler shifts are seen as horizontal brightenings. inside the image it is difficult to distinguish shifts from horizontal structures but emission beyond the image edge can be unambiguously identified as a line shift in several lines separated from others on their blue or red side by more than the width of the spectrometer slit ( 40 pixels ). in the blue wing of he ii, we find a large number of events with properties ( size and lifetime ) similar to the well - studied explosive events seen in the ultraviolet spectral range. comparison with x - ray telescope ( xrt ) images shows many doppler shift events at the footpoints of small x - ray loops. the most spectacular event observed showed a strong blue shift in transition region and lower corona lines from a small x - ray spot that lasted less than 7 min. the emission appears to be near a cool coronal loop connecting an x - ray bright point to an adjacent region of quiet sun. the width of the emission implies a line - of - sight velocity of 220 km / s. in addition, we show an example of an fe xv shift with a velocity about 120 km / s, coming from what looks like a narrow loop leg connecting a small x - ray brightening to a larger region of x - ray emission. | arxiv:0807.1185 |
differential cross sections of the exclusive process $ e p \ to e ^ \ prime \ pi ^ + n $ were measured with good precision in the range of the photon virtuality $ q ^ 2 = 1. 8 - 4. 5 $ gev $ ^ 2 $, and the invariant mass range of the $ \ pi ^ + n $ final state w = 1. 6 - 2. 0 gev using the cebaf large acceptance spectrometer. data were collected with nearly complete coverage in the azimuthal and polar angles of the $ n \ pi ^ + $ center - of - mass system. more than 37, 000 cross section points were measured. the contributions of the isospin $ i = { 1 \ over 2 } $ resonances $ n ( 1675 ) { 5 \ over 2 } ^ - $, $ n ( 1680 ) { 5 \ over 2 } ^ + $ and $ n ( 1710 ) { 1 \ over 2 } ^ + $ were extracted at different values of $ q ^ 2 $ using a single - channel, energy - dependent resonance amplitude analysis. two different approaches, the unitary isobar model and the fixed - $ t $ dispersion relations, were employed in the analysis. we observe significant strength of the $ n ( 1675 ) { 5 \ over 2 } ^ - $ in the $ a _ { 1 / 2 } $ amplitude, which is in strong disagreement with quark models that predict both transverse amplitudes to be strongly suppressed. for the $ n ( 1680 ) { 5 \ over 2 } ^ + $ we observe a slow changeover from the dominance of the $ a _ { 3 / 2 } $ amplitude at the real photon point ( $ q ^ 2 = 0 $ ) to a $ q ^ 2 $ where $ a _ { 1 / 2 } $ begins to dominate. the scalar amplitude $ s _ { 1 / 2 } $ drops rapidly with $ q ^ 2 $ consistent with quark model prediction. for the $ n ( 1710 ) { 1 \ over 2 } ^ + $ resonance our analysis shows significant strength for the $ a _ { 1 / 2 } $ amplitude at $ q ^ 2 < 2. 5 $ gev $ ^ 2 $. | arxiv:1412.0274 |
we study the growth of the rank of subgroups of finite index in residually finite groups, by relating it to the notion of cost. as a by - product, we show that the ` rank vs. heegaard genus ' conjecture on hyperbolic 3 - manifolds is incompatible with the ` fixed price problem ' in topological dynamics. | arxiv:math/0701361 |
a perfect code $ c $ in a graph $ \ gamma $ is an independent set of vertices of $ \ gamma $ such that every vertex outside of $ c $ is adjacent to a unique vertex in $ c $, and a total perfect code $ c $ in $ \ gamma $ is a set of vertices of $ \ gamma $ such that every vertex of $ \ gamma $ is adjacent to a unique vertex in $ c $. let $ g $ be a finite group and $ x $ a normal subset of $ g $. the cayley sum graph $ \ mathrm { cs } ( g, x ) $ of $ g $ with the connection set $ x $ is the graph with vertex set $ g $ and two vertices $ g $ and $ h $ being adjacent if and only if $ gh \ in x $ and $ g \ neq h $. in this paper, we give some necessary conditions of a subgroup of a given group being a ( total ) perfect code in a cayley sum graph of the group. as applications, the cayley sum graphs of some families of groups which admit a subgroup as a ( total ) perfect code are classified. | arxiv:2210.03336 |
i - balls / oscillons are long - lived and spatially localized solutions of real scalar fields. they are produced in various contexts of the early universe in, such as, the inflaton evolution and the axion evolution. however, their decay process has long been unclear. in this paper, we derive an analytic formula of the decay rate of the i - balls / oscillons within the classical field theory. in our approach, we calculate the poynting vector of the perturbation around the i - ball / oscillon profile by solving a relativistic field equation, with which the decay rate of the i - ball / oscillon is obtained. we also perform a classical lattice simulation and confirm the validity of our analytical formula of the decay rate numerically. | arxiv:1901.06130 |
we describe a reproduction procedure which, given a solution of the $ \ mathfrak { gl } _ { m | n } $ gaudin bethe ansatz equation associated to a tensor product of polynomial modules, produces a family $ p $ of other solutions called the population. to a population we associate a rational pseudodifferential operator $ r $ and a superspace $ w $ of rational functions. we show that if at least one module is typical then the population $ p $ is canonically identified with the set of minimal factorizations of $ r $ and with the space of full superflags in $ w $. we conjecture that the singular eigenvectors ( up to rescaling ) of all $ \ mathfrak { gl } _ { m | n } $ gaudin hamiltonians are in a bijective correspondence with certain superspaces of rational functions. | arxiv:1809.01279 |
avalanche photo detection is commonly used in applications which require single photon sensitivity. we examine the limits of using avalanche photo diodes ( apd ) for characterising photon statistics at high data rates. to identify the regime of linear apd operation we employ a ps - pulsed diode laser with variable repetition rates between 0. 5mhz and 80mhz. we modify the mean optical power of the coherent pulses by applying different levels of well - calibrated attenuation. the linearity at high repetition rates is limited by the apd dead time and a non - linear response arises at higher photon - numbers due to multiphoton events. assuming poissonian input light statistics we ascertain the effective mean photon - number of the incident light with high accuracy. time multiplexed detectors ( tmd ) allow to accomplish photon - number resolution by photon chopping. this detection setup extends the linear response function to higher photon - numbers and statistical methods may be used to compensate for non - linearity. we investigated this effect, compare it to the single apd case and show the validity of the convolution treatment in the tmd data analysis. | arxiv:0709.3053 |
the paper relates two variants of semantic models for natural language, logical functional models and compositional distributional vector space models, by transferring the logic and reasoning from the logical to the distributional models. the geometrical operations of quantum logic are reformulated as algebraic operations on vectors. a map from functional models to vector space models makes it possible to compare the meaning of sentences word by word. | arxiv:1412.8527 |
as a continuation of our previous work \ cite { kv2 } the aim of the recent paper is to investigate the solutions of special inhomogeneous linear functional equations by using spectral synthesis in translation invariant closed linear subspaces of additive / multiadditive functions containing the restrictions of the solutions to finitely generated fields. the idea is based on the fundamental work of m. laczkovich and g. kiss \ cite { kl }. using spectral analysis in some related varieties we can prove the existence of special solutions ( automorphisms ) of the functional equation but the spectral synthesis allows us to describe the entire space of solutions on a large class of finitely generated fields. it is spanned by the so - called exponential monomials which can be given in terms of automorphisms of $ \ cc $ and differential operators. we apply the general theory to some inhomogeneous problems motivated by quadrature rules of approximate integration \ cite { kksz08 }, see also \ cite { kksz } and \ cite { kkszw }. | arxiv:1704.04755 |
we generalize a previous construction of a fermiophobic model to the case of more than one extra $ w $ and $ z $ gauge bosons. we focus in particular on the existence of screening configurations and their implication on the gauge boson mass spectrum. one of these configurations allows for the existence of a set of relatively light new gauge bosons, without violation of the quite restrictive bounds coming from the $ \ rho _ { \ rm nc } $ parameter. the links with bess and degenerate bess models are also discussed. also the signal given here by this more traditional gauge extension of the sm could help to disentangle it from the towers of kaluza - klein states over $ w $ and $ z $ gauge bosons in extra dimensions. | arxiv:hep-ph/9803278 |
let $ v _ { l } $ be the vertex algebra associated to a non - degenerate even lattice $ l $, $ \ theta $ the automorphism of $ v _ { l } $ induced from the $ - 1 $ symmetry of $ l $, and $ v _ { l } ^ { + } $ the fixed point subalgebra of $ v _ { l } $ under the action of $ \ theta $. we classify the irreducible weak $ v _ { l } ^ { + } $ - modules and show that any irreducible weak $ v _ { l } ^ { + } $ - module is isomorphic to a weak submodule of some irreducible weak $ v _ { l } $ - module or to a submodule of some irreducible $ \ theta $ - twisted $ v _ { l } $ - module. | arxiv:1910.07126 |
we study finiteness conditions on large tilting modules over arbitrary rings. we then turn to a hereditary artin algebra r and apply our results to the ( infinite dimensional ) tilting module l that generates all modules without preprojective direct summands. we show that the behaviour of l over its endomorphism ring determines the representation type of r. a similar result holds true for the ( infinite dimensional ) tilting module w that generates the divisible modules. finally, we extend to the wild case some results on baer modules and torsion - free modules proven in [ aht ] for tame hereditary algebras. | arxiv:0804.0815 |
the current status of experiments with snd detector at vepp - 2m e ^ + e ^ - collider in the energy range 2e _ 0 = 400 - 1400 mev and recent results of data analysis for $ \ phi $, $ \ omega $ and $ \ rho $ decays and e ^ + e ^ - annihilation into hadrons are presented. | arxiv:hep-ex/9910057 |
star configurations are certain unions of linear subspaces of projective space that have been studied extensively. we develop a framework for studying a substantial generalization, which we call matroid configurations, whose ideals generalize stanley - reisner ideals of matroids. such a matroid configuration is a union of complete intersections of a fixed codimension. relating these to the stanley - reisner ideals of matroids and using methods of liaison theory allows us, in particular, to describe the hilbert function and minimal generators of the ideal of, what we call, a hypersurface configuration. we also establish that the symbolic powers of the ideal of any matroid configuration are cohen - macaulay. as applications, we study ideals coming from certain complete hypergraphs and ideals derived from tetrahedral curves. we also consider waldschmidt constants and resurgences. in particular, we determine the resurgence of any star configuration and many hypersurface configurations. previously, the only non - trivial cases for which the resurgence was known were certain monomial ideals and ideals of finite sets of points. finally, we point out a connection to secant varieties of varieties of reducible forms. | arxiv:1507.00380 |
css - t codes were recently introduced as quantum error - correcting codes that respect a transversal gate. a css - t code depends on a css - t pair, which is a pair of binary codes $ ( c _ 1, c _ 2 ) $ such that $ c _ 1 $ contains $ c _ 2 $, $ c _ 2 $ is even, and the shortening of the dual of $ c _ 1 $ with respect to the support of each codeword of $ c _ 2 $ is self - dual. in this paper, we give new conditions to guarantee that a pair of binary codes $ ( c _ 1, c _ 2 ) $ is a css - t pair. we define the poset of css - t pairs and determine the minimal and maximal elements of the poset. we provide a propagation rule for nondegenerate css - t codes. we apply some main results to reed - muller, cyclic, and extended cyclic codes. we characterize css - t pairs of cyclic codes in terms of the defining cyclotomic cosets. we find cyclic and extended cyclic codes to obtain quantum codes with better parameters than those in the literature. | arxiv:2312.17518 |
we discuss hilbert - kunz function from when it was originally defined to its recent developments. a brief history of hilbert - kunz theory is first recounted. then we review several techniques involved in the study of hilbert - kunz functions by presenting some illustrative proofs without going into details of the technicalities. the second part of this article focuses on the hilbert - kunz function of an affine normal semigroup ring and relates it to ehrhart quasipolynomials. we pay extra attention to its periodic behavior and discuss how the cellular decomposition constructed by bruns and gubeladze fits into the computation of the functions. the closed forms of the hilbert - kunz function of some examples are presented. the discussion in this part highlights the close relationship between hilbert - kunz function and ehrhart theory. | arxiv:2106.14053 |
fault tree analysis ( fta ) is a prominent technique in industrial and scientific risk assessment. repairable fault trees ( rft ) enhance the classical fault tree ( ft ) model by introducing the possibility to describe complex dependent repairs of system components. usual frameworks for analyzing fts such as bdd, sbdd, and markov chains fail to assess the desired properties over rft complex models, either because these become too large, or due to cyclic behaviour introduced by dependent repairs. simulation is another way to carry out this kind of analysis. in this paper we review the rft model with repair boxes as introduced by daniele codetta - raiteri. we present compositional semantics for this model in terms of input / output stochastic automata, which allows for the modelling of events occurring according to general continuous distribution. moreover, we prove that the semantics generates ( weakly ) deterministic models, hence suitable for discrete event simulation, and prominently for rare event simulation using the fig tool. | arxiv:1910.10507 |
in the presence of independent generations of leptons, i show that the same type of ambiguity in the mass spectrum arises as was discussed in ref. [ 1 ] for neutral kaons. it results from the freedom to add to their majorana mass matrix, usually taken to be symmetric, an antisymmetric term which vanishes as soon as fermions belonging to different generations anticommute. in the simple examples proposed, dealing with two generations, this procedure introduces an extra ( mass ) parameter $ \ rho $, which is shown to connect the ( cp violating ) mixing angle to the hierarchy of neutrino masses. we use this opportunity to investigate the relations between the two ; in particular, large hierarchies are no longer preferentially attached to small mixing angles ; this can be relevant for the ` ` large mixing angle ' ' solution strongly advocated by recent experiments on neutrinos oscillations. i discuss how the $ \ rho $ parameter could be fixed, which appears, in the absence of a substructure for leptons, still more delicate than for kaons. | arxiv:hep-ph/0207040 |
we have unified quantum and classical computing in open quantum systems called qacp which is a quantum generalization of process algebra acp. but, an axiomatization for quantum and classical processes with an assumption of closed quantum systems is still missing. for closed quantum systems, unitary operator, quantum measurement and quantum entanglement are three basic components for quantum computing. this leads to probability unavoidable. along the solution of qacp to unify quantum and classical computing in open quantum systems, we unify quantum and classical computing with an assumption of closed systems under the framework of acp - like probabilistic process algebra. this unification make it can be used widely in verification for quantum and classical computing mixed systems, such as most quantum communication protocols. | arxiv:1610.02500 |
methods based on supervised learning using annotations in an end - to - end fashion have been the state - of - the - art for classification problems. however, they may be limited in their generalization capability, especially in the low data regime. in this study, we address this issue using supervised contrastive learning combined with available metadata to solve multiple pretext tasks that learn a good representation of data. we apply our approach on respiratory sound classification. this task is suited for this setting as demographic information such as sex and age are correlated with presence of lung diseases, and learning a system that implicitly encode this information may better detect anomalies. supervised contrastive learning is a paradigm that learns similar representations to samples sharing the same class labels and dissimilar representations to samples with different class labels. the feature extractor learned using this paradigm extract useful features from the data, and we show that it outperforms cross - entropy in classifying respiratory anomalies in two different datasets. we also show that learning representations using only metadata, without class labels, obtains similar performance as using cross entropy with those labels only. in addition, when combining class labels with metadata using multiple supervised contrastive learning, an extension of supervised contrastive learning solving an additional task of grouping patients within the same sex and age group, more informative features are learned. this work suggests the potential of using multiple metadata sources in supervised contrastive settings, in particular in settings with class imbalance and few data. our code is released at https : / / github. com / ilyassmoummad / scl _ icbhi2017 | arxiv:2210.16192 |
mathematical logic and to minimize the number of primitive notions, axioms, and inference rules ; to precisely express mathematical propositions in symbolic logic using the most convenient notation that precise expression allows ; to solve the paradoxes that plagued logic and set theory at the turn of the 20th century, like russell ' s paradox. there is no doubt that principia mathematica is of great importance in the history of mathematics and philosophy : as irvine has noted, it sparked interest in symbolic logic and advanced the subject by popularizing it ; it showcased the powers and capacities of symbolic logic ; and it showed how advances in philosophy of mathematics and symbolic logic could go hand - in - hand with tremendous fruitfulness. indeed, the work was in part brought about by an interest in logicism, the view on which all mathematical truths are logical truths. it was in part thanks to the advances made in principia mathematica that, despite its defects, numerous advances in meta - logic were made, including godel ' s incompleteness theorems. = = michel foucault = = in the order of things, michel foucault discuses mathesis as the conjunction point in the ordering of simple natures and algebra, paralleling his concept of taxinomia. though omitting explicit references to universality, foucault uses the term to organise and interpret all of human science, as is evident in the full title of his book : " the order of things : an archaeology of the human sciences ". = = tim maudlin = = tim maudlin ' s mathematical universe hypothesis attempts to construct " a rigorous mathematical structure using primitive terms that give a natural fit with physics " and investigating why mathematics should provide such a powerful language for describing the physical world. according to maudlin, " the most satisfying possible answer to such a question is : because the physical world literally has a mathematical structure ". = = see also = = digital physics mathematical psychology modern platonism unit - point atomism wolfram physics project mathematical universe hypothesis characteristica universalis de arte combinatoria an essay towards a real character, and a philosophical language lingua generalis = = references = = = = bibliography = = = = external links = = media related to mathematicism at wikimedia commons raul corazzon ' s ontology web page : mathesis universalis with a bibliography " mathematicism ". britannica. " mathematicism ". collins dictionary. " mathematicism ". oxford living dictionary | https://en.wikipedia.org/wiki/Mathematicism |
new experimental results on the spin dependent structure functions g _ 1 and g _ 2 which are determined from deep - inelastic scattering experiments at cern, slac and desy are reported. these results are used to evaluate the bjorken sum rule and the singlet axial charge a _ 0. results are discussed in the framework of next - to - leading order perturbative qcd. the role of the polarised gluons in the interpretation of the results on a _ 0 is emphasised. new experiments which aim to determine gluon polarisation are shortly described. | arxiv:hep-ph/9612352 |
motivated by indirect observational evidence for strongly magnetized accretion discs around black holes, and the novel theoretical properties of such solutions, we investigate how a strong magnetization state can develop and persist. to this end, we perform local simulations of accretion discs with an initially purely toroidal magnetic field of equipartition strength. we demonstrate that discs with zero net vertical magnetic flux and realistic boundary conditions cannot sustain a strong toroidal field. however, a magnetic pressure - dominated disc can form from an initial configuration with a sufficient amount of net vertical flux and realistic boundary conditions. our results suggest that poloidal flux is a necessary prerequisite for the sustainability of strongly magnetized accretion discs. | arxiv:1602.04810 |
we revisit the problem of constructing type iia orientifolds on t ^ 6 / ( z2 x z2 ) which admit ( non ) - factorisable lattices. more concretely, we consider a ( z2 x z2 ' ) orientifold with torsion, where d6 - branes wrap rigid 3 - cycles. we derive the model building rules and consistency conditions in the case where the compactification lattice is non - factorisable. we show that in this class of configurations, ( semi ) realistic models with an odd number of families can be easily constructed, in contrast to compactifications where the d6 - branes wrap non - rigid cycles. we also show that an odd number of families can be obtained in the factorisable case, without the need of tilted tori. we illustrate the discussion by presenting three family pati - salam models with no chiral exotics in both factorisable and non - factorisable toroidal compactifications. | arxiv:0806.2328 |
in math. gr / 0510298, we showed that every f - quasigroup is linear over a special kind of moufang loop called an nk - loop. here we extend this relationship by showing an equivalence between the equational class of ( pointed ) f - quasigroups and the equational class corresponding to a certain notion of generalized module ( with noncommutative, nonassociative addition ) for an associative ring. | arxiv:math/0512244 |
in this paper, we discuss the fixed point property for an infinite family of order - preserving mappings which satisfy the lipschitzian condition on comparable pairs. the underlying framework of our main results is a metric space of any global upper curvature bound $ \ kappa \ in \ mathbb { r } $, i. e., a $ \ rm { cat } ( \ kappa ) $ space. in particular, we prove the existence of a fixed point for a nonexpasive semigroup on comparable pairs. then, we propose and analyze two algorithms to approximate such a fixed point. | arxiv:1811.11585 |
a comprehensive search for variable and transient radio sources has been conducted using ~ 55, 000 snapshot images of the first survey. we present an analysis leading to the discovery of 1, 627 variable and transient objects down to mjy levels over a wide range of timescales ( few minutes to years ). variations observed range from 20 % to a factor of 25. multi - wavelength matching for counterparts reveals the diverse classes of objects exhibiting variability, ranging from nearby stars and pulsars to galaxies and distant quasars. interestingly, more than half of the objects in the sample have either no classified counterparts or no corresponding sources at any other wavelength and require multi - wavelength follow - up observations. we discuss these classes of variables and speculate on the identity of objects that lack multi - wavelength counterparts. | arxiv:1107.5901 |
using the sign expansion of the surreal numbers, we give a possible notion of convergence for surreal sequences. | arxiv:1210.5675 |
in this paper we introduce new methods for convex optimization problems with inexact stochastic oracle. first method is an extension of the intermediate gradient method proposed by devolder, glineur and nesterov for problems with inexact oracle. our new method can be applied to the problems with composite structure, stochastic inexact oracle and allows using non - euclidean setup. we prove estimates for mean rate of convergence and probabilities of large deviations from this rate. also we introduce two modifications of this method for strongly convex problems. for the first modification we prove mean rate of convergence estimates and for the second we prove estimates for large deviations from the mean rate of convergence. all the rates give the complexity estimates for proposed methods which up to multiplicative constant coincide with lower complexity bound for the considered class of convex composite optimization problems with stochastic inexact oracle. | arxiv:1411.2876 |
the words of a language reflect the structure of the human mind, allowing us to transmit thoughts between individuals. however, language can represent only a subset of our rich and detailed cognitive architecture. here, we ask what kinds of common knowledge ( semantic memory ) are captured by word meanings ( lexical semantics ). we examine a prominent computational model that represents words as vectors in a multidimensional space, such that proximity between word - vectors approximates semantic relatedness. because related words appear in similar contexts, such spaces - called " word embeddings " - can be learned from patterns of lexical co - occurrences in natural language. despite their popularity, a fundamental concern about word embeddings is that they appear to be semantically " rigid " : inter - word proximity captures only overall similarity, yet human judgments about object similarities are highly context - dependent and involve multiple, distinct semantic features. for example, dolphins and alligators appear similar in size, but differ in intelligence and aggressiveness. could such context - dependent relationships be recovered from word embeddings? to address this issue, we introduce a powerful, domain - general solution : " semantic projection " of word - vectors onto lines that represent various object features, like size ( the line extending from the word " small " to " big " ), intelligence ( from " dumb " to " smart " ), or danger ( from " safe " to " dangerous " ). this method, which is intuitively analogous to placing objects " on a mental scale " between two extremes, recovers human judgments across a range of object categories and properties. we thus show that word embeddings inherit a wealth of common knowledge from word co - occurrence statistics and can be flexibly manipulated to express context - dependent meanings. | arxiv:1802.01241 |
as robots aspire for long - term autonomous operations in complex dynamic environments, the ability to reliably take mission - critical decisions in ambiguous situations becomes critical. this motivates the need to build systems that have situational awareness to assess how qualified they are at that moment to make a decision. we call this self - evaluating capability as introspection. in this paper, we take a small step in this direction and propose a generic framework for introspective behavior in perception systems. our goal is to learn a model to reliably predict failures in a given system, with respect to a task, directly from input sensor data. we present this in the context of vision - based autonomous mav flight in outdoor natural environments, and show that it effectively handles uncertain situations. | arxiv:1607.08665 |
the united states has long pursued regulations that aim to reduce fossil fuel use. however, while potential emission reduction motivates the introduction and enforcement of these regulations, realization of this potential does not obfuscate the need for prudent economic policy. scrutinizing nearly two decades of climate regulations in the transportation, industrial, and electric power sector, we enumerate their associated cost effectiveness. our findings are twofold. firstly, we find that whereas there are instances where climate regulations carry net economic benefits, there are also cases where compliance costs substantially exceed the social cost of carbon ( scc ). aggregated across sectors and subject to the precise scc leveraged, up to 65 percent of climate regulations have abatement costs that exceed the scc. this exceedance is particularly profound in the transportation sector where up to 82 percent of regulations reviewed have abatement costs that exceed the scc. secondly, we find that whereas the economic benefits of climate regulations generally exceed the economic costs, this exceedance is largely contingent on the presence of non - climate benefits. aggregated across sectors, climate benefits account for 33 percent of overall benefits associated with a regulation, compared to 18, 46, and 2 percent for public health, private, and other benefits respectively. furthermore, we document instances where climate benefits account for as little as 1. 6 percent of overall regulatory benefits. this finding hints at a regulatory inefficiency and raises the prospect that alternative, non - climate specific regulation may be a more appropriate mechanism for realizing the non - climate benefits associated with these regulations. collectively, our findings challenge the economic pragmatism of some ( but not all ) climate regulations adopted by the united states over a period of nearly two decades. | arxiv:2503.11406 |
in this paper, we tackle the task of establishing dense visual correspondences between images containing objects of the same category. this is a challenging task due to large intra - class variations and a lack of dense pixel level annotations. we propose a convolutional neural network architecture, called adaptive neighbourhood consensus network ( anc - net ), that can be trained end - to - end with sparse key - point annotations, to handle this challenge. at the core of anc - net is our proposed non - isotropic 4d convolution kernel, which forms the building block for the adaptive neighbourhood consensus module for robust matching. we also introduce a simple and efficient multi - scale self - similarity module in anc - net to make the learned feature robust to intra - class variations. furthermore, we propose a novel orthogonal loss that can enforce the one - to - one matching constraint. we thoroughly evaluate the effectiveness of our method on various benchmarks, where it substantially outperforms state - of - the - art methods. | arxiv:2003.12059 |
in the field of spaceflight mechanics and astrodynamics, determining eclipse regions is a frequent and critical challenge. this determination impacts various factors, including the acceleration induced by solar radiation pressure, the spacecraft power input, and its thermal state all of which must be accounted for in various phases of the mission design. this study leverages recent advances in neural image processing to develop fully differentiable models of eclipse regions for highly irregular celestial bodies. by utilizing test cases involving solar system bodies previously visited by spacecraft, such as 433 eros, 25143 itokawa, 67p / churyumov - - gerasimenko, and 101955 bennu, we propose and study an implicit neural architecture defining the shape of the eclipse cone based on the sun ' s direction. employing periodic activation functions, we achieve high precision in modeling eclipse conditions. furthermore, we discuss the potential applications of these differentiable models in spaceflight mechanics computations. | arxiv:2408.05387 |
a rainbow - ladder truncation of qcd ' s dyson - schwinger equations, constrained by existing applications to hadron physics, is employed to compute the valence - quark parton distribution functions of the pion and kaon. comparison is made to pi - n drell - yan data for the pion ' s u - quark distribution and to drell - yan data for the ratio u _ k ( x ) / u _ \ pi ( x ) : the environmental influence of this quantity is a parameter - free prediction, which agrees well with existing data. our analysis unifies the computation of distribution functions with that of numerous other properties of pseudoscalar mesons. | arxiv:1102.2448 |
we define twisted alexander polynomials of a complex hypersurface with arbitrary singularities. these generalize the classical alexander polynomials of high dimensional hypersurfaces and the twisted alexander polynomial of plane curves. we recover the classical torsionness and divisibility results, which say that, under certain assumptions, the twisted alexander modules of a complex hypersurface are torsion modules, and that their orders, the twisted alexander polynomials, divide the product of certain ` local polynomials ' defined in terms of the topology near singularities. | arxiv:1501.06065 |
we study holomorphic foliations of codimension $ k \ geq 1 $ on a complex manifold $ x $ of dimension $ n + k $ from the point of view of the exceptional minimal set conjecture. for $ n \ geq 2 $ we show in particular that if the holomorphic normal bundle $ n _ { \ mathcal { f } } $ is griffiths positive, then the foliation does not admit a compact invariant set that is a complete intersection of $ k $ smooth real hypersurfaces in $ x $. | arxiv:1910.01930 |
we consider a networked control system ( ncs ) consisting of two plants, a global plant and a local plant, and two controllers, a global controller and a local controller. the global ( resp. local ) plant follows discrete - time stochastically switched linear dynamics with a continuous global ( resp. local ) state and a discrete global ( resp. local ) mode. we assume that the state and mode of the global plant are observed by both controllers while the state and mode of the local plant are only observed by the local controller. the local controller can inform the global controller of the local plant ' s state and mode through an unreliable tcp - like communication channel where successful transmissions are acknowledged. the objective of the controllers is to cooperatively minimize a modes - dependent quadratic cost over a finite time horizon. following the method developed in [ 1 ] and [ 2 ], we construct a dynamic program based on common information and a decomposition of strategies, and use it to obtain explicit optimal strategies for the controllers. in the optimal strategies, both controllers compute a common estimate of the local plant ' s state. the global controller ' s action is linear in the state of the global plant and the common estimated state, and the local controller ' s action is linear in the actual states of both plants and the common estimated state. furthermore, the gain matrices for the global controller depend on the global mode and its observation about the local mode, while the gain matrices for the local controller depend on the actual modes of both plants and the global controller ' s observation about the local mode. | arxiv:1802.00538 |
we analyze site percolation on directed and undirected graphs with site - dependent open - site probabilities. we construct upper bounds on cluster susceptibilities, vertex connectivity functions, and the expected number of simple open cycles through a chosen arc ; separate bounds are given on finite and infinite ( di ) graphs. these produce lower bounds for percolation and uniqueness transitions in infinite ( di ) graphs, and for the formation of a giant component in finite ( di ) graphs. the bounds are formulated in terms of appropriately weighted adjacency and non - backtracking ( hashimoto ) matrices. it turns out to be the uniqueness criterion that is most closely associated with an asymptotically vanishing probability of forming a giant strongly - connected component on a large finite ( di ) graph. | arxiv:1505.03963 |
we compare different polyakov loop actions yielding effective descriptions of finite - temperature su ( 2 ) yang - mills theory on the lattice. the actions are motivated by a simultaneous strong - coupling and character expansion obeying center symmetry and include both ising and ginzburg - landau type models. to keep things simple we limit ourselves to nearest - neighbor interactions. some truncations involving the most relevant characters are studied within a novel mean - field approximation. using inverse monte - carlo techniques based on exact geometrical schwinger - dyson equations we determine the effective couplings of the polyakov loop actions. monte - carlo simulations of these actions reveal that the mean - field analysis is a fairly good guide to the physics involved. our polyakov loop actions reproduce standard yang - mills observables well up to limitations due to the nearest - neighbor approximation. | arxiv:hep-lat/0502013 |
twitter is a popular microblogging platform. when users send out messages, other users have the ability to forward these messages to their own subgraph. most research focuses on increasing retweetability from a node ' s perspective. here, we center on improving message style to increase the chance of a message being forwarded. to this end, we simulate an artificial twitter - like network with nodes deciding deterministically on retweeting a message or not. a genetic algorithm is used to optimize message composition, so that the reach of a message is increased. when analyzing the algorithm ' s runtime behavior across a set of different node types, we find that the algorithm consistently succeeds in significantly improving the retweetability of a message. | arxiv:1401.4857 |
infrared studies have revealed debris likely related to planet formation in orbit around ~ 30 % of youthful, intermediate mass, main sequence stars. we present evidence, based on atmospheric pollution by various elements heavier than helium, that a comparable fraction of the white dwarf descendants of such main sequence stars are orbited by planetary systems. these systems have survived, at least in part, through all stages of stellar evolution that precede the white dwarf. during the time interval ( ~ 200 million years ) that a typical polluted white dwarf in our sample has been cooling it has accreted from its planetary system the mass of one of the largest asteroids in our solar system ( e. g., vesta or ceres ). usually, this accreted mass will be only a fraction of the total mass of rocky material that orbits these white dwarfs ; for plausible planetary system configurations we estimate that this total mass is likely to be at least equal to that of the sun ' s asteroid belt, and perhaps much larger. we report abundances of a suite of 8 elements detected in the little studied star g241 - 6 that we find to be among the most heavily polluted of all moderately bright white dwarfs. | arxiv:1007.2252 |
we show that cosmic rays in external galaxies, groups and clusters rich in gas, with an average flux similar to that observed in the milky way, could have produced the observed extragalactic diffuse gamma radiation. | arxiv:astro-ph/9501079 |
in this paper, we present a discrete - time networked seir model using population flow, its derivation, and assumptions under which this model is well defined. we identify properties of the system ' s equilibria, namely the healthy states. we show that the set of healthy states is asymptotically stable, and that the value of the equilibria becomes equal across all sub - populations as a result of the network flow model. furthermore, we explore closed - loop feedback control of the system by limiting flow between sub - populations as a function of the current infected states. these results are illustrated via simulation based on flight traffic between major airports in the united states. we find that a flow restriction strategy combined with a vaccine roll - out significantly reduces the total number of infections over the course of an epidemic, given that the initial flow restriction response is not delayed. | arxiv:2104.07600 |
we consider here the spin independent neutralino - proton cross section for a variety of sugra and d - brane models with r - parity invariance. the minimum cross section generally is > ~ 1 \ times 10 ^ { - ( 9 - 10 ) } pb ( and hence accessible to future detectors ) except for special regions of parameter space where it may drop to = ~ 10 ^ { - 12 } pb. in the latter case the gluino and squarks will be heavy ( > ~ 1 tev ). | arxiv:hep-ph/0008320 |
we report about the current status of our ongoing study of the chiral limit of two - flavor qcd at finite temperature with twisted mass quarks. we estimate the pseudo - critical temperature $ t _ c $ for three values of the pion mass in the range of $ m _ \ mathrm { ps } \ simeq 300 $ and $ 500 \ mathrm { mev } $ and discuss different chiral scenarios. furthermore, we present first preliminary results for the trace anomaly, pressure and energy density. we have studied several discretizations of euclidean time up to $ n _ \ tau = 12 $ in order to assess the continuum limit of the trace anomaly. from its interpolation we evaluate the pressure and energy density employing the integral method. here, we have focussed on two pion masses with $ m _ \ mathrm { ps } \ simeq 400 $ and $ 700 \ mathrm { mev } $. | arxiv:1212.0982 |
in this paper we express the minkowski dimension of spiral trajectories near hyperbolic saddles and semi - hyperbolic singularities in terms of the minkowski dimension of intersections of such spirals with transversals near these singularities. we apply these results to hyperbolic saddle - loops and hyperbolic $ 2 $ - cycles to obtain upper bounds on the cyclicity of such limit periodic sets. | arxiv:2306.00116 |
in this paper, we focus on a novel knowledge reuse scenario where the knowledge in the source schema needs to be translated to a semantically heterogeneous target schema. we refer to this task as " knowledge translation " ( kt ). unlike data translation and transfer learning, kt does not require any data from the source or target schema. we adopt a probabilistic approach to kt by representing the knowledge in the source schema, the mapping between the source and target schemas, and the resulting knowledge in the target schema all as probability distributions, specially using markov random fields and markov logic networks. given the source knowledge and mappings, we use standard learning and inference algorithms for probabilistic graphical models to find an explicit probability distribution in the target schema that minimizes the kullback - leibler divergence from the implicit distribution. this gives us a compact probabilistic model that represents knowledge from the source schema as well as possible, respecting the uncertainty in both the source knowledge and the mapping. in experiments on both propositional and relational domains, we find that the knowledge obtained by kt is comparable to other approaches that require data, demonstrating that knowledge can be reused without data. | arxiv:1507.03181 |
the flow field of a bluff body, a circular disk, that moves horizontally in a stratified environment is studied using large eddy simulations ( les ). five levels of stratification ( body froude numbers of fr = 0. 5, 1, 1. 5, 2 and 5 ) are simulated at reynolds number of re = 5000 and prandtl number of pr = 1. a higher re = 50, 000 database at fr = 2, 10 and pr = 1 is also examined for comparison. the wavelength and amplitude of steady lee waves are compared with a linear - theory analysis. excellent agreement is found over the entire range of fr if an equivalent body that includes the separation region is employed for the linear theory. for asymptotically large distance, the velocity amplitude varies theoretically as fr raised to negative 1 but a correction owing to dependence of the separation zone on fr is needed. the wake waves propagate in a narrow band of angles with the vertical and have a wavelength that increases with increasing fr. the envelope of wake waves, demarcated using buoyancy variance, exhibits self - similar behavior. the higher re results are consistent with the buoyancy effects exhibited at the lower re. the wake wave energy is larger at re = 50000. nevertheless, independent of fr and re, the ratio of the wake wave potential energy to the wake turbulent energy increases to approximately 0. 6 to 0. 7 in the nonequilibrium ( neq ) stage showing their energetic importance besides suggesting universality in this statistic. there is a crossover of energetic dominance of lee waves at fr less than 2 to wake - wave dominance at fr approximately equal to 5. | arxiv:2408.14683 |
smoothing is a technique for estimating the state of an imperfectly monitored open system by combining both prior and posterior measurement information. in the quantum regime, current approaches to smoothing either give unphysical outcomes, due to the non - commutativity of the measurements at different times, or require assumptions about how the environment is measuring the system, which with current technology is unverifiable. we propose a novel definition of the smoothed quantum state based on quantum bayesian retrodiction, which mirrors the classical retrodictive approach to smoothing. this approach always yields physical results and does not require any assumption on the environment. we show that this smoothed state has, on average, greater purity than the state reconstructed using just the prior information. finally, we make a connection with the smoothing theory of guevara and wiseman in a well - studied regime, and describe from a purely quantum perspective how it conditions on the posterior information. | arxiv:2501.15986 |
the preferential formation of one solid over the other, as it precipitates out from the melt at specific temperatures, is often explained by invoking a competition between thermodynamic and kinetic control. a quantitative theory, however, could not be developed because of the lack of accurate values of relevant surface tension terms. motivated by the observations that wetting of the interface between two stable phases by multiple metastable phases of intermediate order can reduce the surface tension significantly ( kirkpatrick - thirumalai - wolynes ( ktw ), phys. rev. a 1989, 40 ( 2 ), 1045 ; santra et al., j. phys. chem. b, 2013, 117, 13154 ), we develop a statistical mechanical approach based on a landau - ginzburg type free energy functional to calculate the surface tension between two stable phases in the presence of n number of metastable phases. simple model calculations are performed that show the surface tension between two coexisting stable phases ( melt and the stable crystalline forms ) depends significantly on the number, relative depths and arrangements of the free energy minima of the metastable phases, in addition to the size of the nucleus. we provide an explanation of the quickly disappearing polymorphs ( qdpms ) that often melt back to the liquid ( or, the sol ) phase. it is shown that our model systems could describe some aspects of solid formation in real polymorphic systems, like phosphates and zeolites. | arxiv:1809.00299 |
in recommender systems, cold - start issues are situations where no previous events, e. g. ratings, are known for certain users or items. in this paper, we focus on the item cold - start problem. both content information ( e. g. item attributes ) and initial user ratings are valuable for seizing users ' preferences on a new item. however, previous methods for the item cold - start problem either 1 ) incorporate content information into collaborative filtering to perform hybrid recommendation, or 2 ) actively select users to rate the new item without considering content information and then do collaborative filtering. in this paper, we propose a novel recommendation scheme for the item cold - start problem by leverage both active learning and items ' attribute information. specifically, we design useful user selection criteria based on items ' attributes and users ' rating history, and combine the criteria in an optimization framework for selecting users. by exploiting the feedback ratings, users ' previous ratings and items ' attributes, we then generate accurate rating predictions for the other unselected users. experimental results on two real - world datasets show the superiority of our proposed method over traditional methods. | arxiv:1805.09023 |
recent works on crowd counting mainly leverage cnns to count by regressing density maps, and have achieved great progress. in the density map, each person is represented by a gaussian blob, and the final count is obtained from the integration of the whole map. however, it is difficult to accurately predict the density map on dense regions. a major issue is that the density map on dense regions usually accumulates density values from a number of nearby gaussian blobs, yielding different large density values on a small set of pixels. this makes the density map present variant patterns with significant pattern shifts and brings a long - tailed distribution of pixel - wise density values. we propose a simple and effective learning to scale ( l2s ) module, which automatically scales dense regions into reasonable closeness levels ( reflecting image - plane distance between neighboring people ). l2s directly normalizes the closeness in different patches such that it dynamically separates the overlapped blobs, decomposes the accumulated values in the ground - truth density map, and thus alleviates the pattern shifts and long - tailed distribution of density values. this helps the model to better learn the density map. we also explore the effectiveness of l2s in localizing people by finding the local minima of the quantized distance ( w. r. t. person location map ). to the best of our knowledge, such a localization method is also novel in localization - based crowd counting. we further introduce a customized dynamic cross - entropy loss, significantly improving the localization - based model optimization. extensive experiments demonstrate that the proposed framework termed autoscale improves upon some state - of - the - art methods in both regression and localization benchmarks on three crowded datasets and achieves very competitive performance on two sparse datasets. | arxiv:1912.09632 |
large language models ( llms ) have demonstrated impressive capabilities across natural language processing tasks. however, their application to specialized domains such as medicine and biology requires further optimization to ensure factual accuracy, reliability, and contextual depth. we introduce medbiolm, a domain - adapted biomedical question - answering model designed to enhance both short - form and long - form queries. by integrating fine - tuning and retrieval - augmented generation ( rag ), medbiolm dynamically incorporates domain - specific knowledge, improving reasoning abilities and factual accuracy. to evaluate its effectiveness, we fine - tuned the model on diverse biomedical qa datasets, covering structured multiple - choice assessments and complex clinical reasoning tasks. fine - tuning significantly improves accuracy on benchmark datasets, while rag enhances factual consistency. these results highlight the potential of domain - optimized llms in advancing biomedical research, medical education, and clinical decision support. | arxiv:2502.03004 |
according to brønsted – lowry acid – base theory, acids are substances that donate a positive hydrogen ion to another substance in a chemical reaction ; by extension, a base is the substance which receives that hydrogen ion. a third common theory is lewis acid – base theory, which is based on the formation of new chemical bonds. lewis theory explains that an acid is a substance which is capable of accepting a pair of electrons from another substance during the process of bond formation, while a base is a substance which can provide a pair of electrons to form a new bond. there are several other ways in which a substance may be classified as an acid or a base, as is evident in the history of this concept. acid strength is commonly measured by two methods. one measurement, based on the arrhenius definition of acidity, is ph, which is a measurement of the hydronium ion concentration in a solution, as expressed on a negative logarithmic scale. thus, solutions that have a low ph have a high hydronium ion concentration and can be said to be more acidic. the other measurement, based on the brønsted – lowry definition, is the acid dissociation constant ( ka ), which measures the relative ability of a substance to act as an acid under the brønsted – lowry definition of an acid. that is, substances with a higher ka are more likely to donate hydrogen ions in chemical reactions than those with lower ka values. = = = redox = = = redox ( reduction - oxidation ) reactions include all chemical reactions in which atoms have their oxidation state changed by either gaining electrons ( reduction ) or losing electrons ( oxidation ). substances that have the ability to oxidize other substances are said to be oxidative and are known as oxidizing agents, oxidants or oxidizers. an oxidant removes electrons from another substance. similarly, substances that have the ability to reduce other substances are said to be reductive and are known as reducing agents, reductants, or reducers. a reductant transfers electrons to another substance and is thus oxidized itself. and because it " donates " electrons it is also called an electron donor. oxidation and reduction properly refer to a change in oxidation number — the actual transfer of electrons may never occur. thus, oxidation is better defined as an increase in oxidation number, and reduction as a decrease in oxidation number. = = = equilibrium = = = although the concept of equilibrium is widely used across sciences, in | https://en.wikipedia.org/wiki/Chemistry |
we have used sensitive low frequency array ( lofar ) observations of psr b0809 + 74 at 15 - - 62 mhz to study the anomalously intensive pulses, first reported by ulyanov et al. ( 2006 ) at 18 - - 30mhz. similarly to ulyanov et al., we found that the spectra of strong pulses consist of distinct bright patches. moreover, these spectral patches were spotted to drift upwards in frequency over the course of several pulse sequences. we established that this drift is not pulsar - intrinsic, but is caused by the broadband ~ 20 second - long enhancements of recorded signal, which influenced the dispersed tracks of several pulses at once. we speculate on the cause of such enhancements ( i. e. propagation or telescope - related ) and the ramifications they bring to the single - pulse studies at the very low radio frequencies. depending on the origin, the phenomenon may also affect the analysis of highly dispersed single pulses at higher radio frequencies, e. g. fast radio bursts. | arxiv:1711.07346 |
we construct the screening currents of the quantum superalgebra $ u _ q ( \ hat { sl } ( n | 1 ) ) $ for an arbitrary level $ k \ neq - n + 1 $. we show that these screening currents commute with the superalgebra modulo total difference. we propose bosonizations of the vertex operators by using the screening currents. we check that these vertex operators are the intertwiners among the fock - wakimoto representation and the typical representation for rank $ n \ leq 4 $. | arxiv:1201.4223 |
the tolman - oppenheimer - volkoff ( tov ) equation admits singular solutions in addition to regular ones. here, we prove the following theorem. for any equation of state that ( i ) is obtained from an entropy function, ( ii ) has positive pressure and ( iii ) satisfies the dominant energy condition, the tov equation can be integrated from a boundary inwards to the center. hence, thermodynamic consistency of the eos precludes pathological solutions, in which the integration terminates at finite radius ( because of horizons, or divergences / zeroes of energy density ). at the center, the mass function either vanishes ( regular solutions ) or it is negative ( singular solutions ). for singular solutions, the metric at the center is locally isomorphic to negative - mass schwarzschild spacetime. this means that matter is stabilized because the singularity is strongly repulsive. we show that singular solutions are causally well behaved : they are bounded - acceleration complete, and they are conformal to a globally hyperbolic spacetime with boundary. finally, we show how to modify unphysical equations of state in order to obtain non - pathological solutions, and we undertake a preliminary investigation of dynamical stability for singular solutions. | arxiv:2010.02279 |
the s - wave scattering length for elastic collisions between 87rb atoms in the state | f, m _ f > = | 1, 1 > is measured in the vicinity of a feshbach resonance near 1007 g. experimentally, the scattering length is determined from the mean - field driven expansion of a bose - einstein condensate in a homogeneous magnetic field. the scattering length is measured as a function of the magnetic field and agrees with the theoretical expectation. the position and the width of the resonance are determined to be 1007. 40 g and 0. 20 g, respectively. | arxiv:cond-mat/0305180 |
identifying important nodes for disease spreading is a central topic in network epidemiology. we investigate how well the position of a node, characterized by standard network measures, can predict its epidemiological importance in any graph of a given number of nodes. this is in contrast to other studies that deal with the easier prediction problem of ranking nodes by their epidemic importance in given graphs. as a benchmark for epidemic importance, we calculate the exact expected outbreak size given a node as the source. we study exhaustively all graphs of a given size, so do not restrict ourselves to certain generative models for graphs, nor to graph data sets. due to the large number of possible nonisomorphic graphs of a fixed size, we are limited to 10 - node graphs. we find that combinations of two or more centralities are predictive ( $ r ^ 2 $ scores of 0. 91 or higher ) even for the most difficult parameter values of the epidemic simulation. typically, these successful combinations include one normalized spectral centralities ( such as pagerank or katz centrality ) and one measure that is sensitive to the number of edges in the graph. | arxiv:1909.10021 |
we define an equivariant $ k _ 0 $ - theory for \ textit { yetter - drinfeld } algebras over a hopf algebra with an invertible antipode. we then show that this definition can be generalized to all hopf - module algebras. we show that there exists a pairing, generalizing connes ' pairing, between this theory and a suitably defined hopf algebra equivariant cyclic cohomology theory. | arxiv:math/0009236 |
we compute the pair entanglement between two interacting bosons in a two dimensional ( 2d ) isotropic harmonic trap. the interaction potential is modeled by a 2d regularized pseudo - potential. by analytically decomposing the wave function into the single particle basis, we show the dependency of the pair entanglement on the scattering length. our results turn out to be in good agreements with earlier results using a quasi - 2d geometry. | arxiv:0910.1765 |
in this paper, we study the stability of the conical k \ " ahler - ricci flows on fano manifolds. that is, if there exists a conical k \ " ahler - einstein metric with cone angle $ 2 \ pi \ beta $ along the divisor, then for any $ \ beta ' $ sufficiently close to $ \ beta $, the corresponding conical k \ " ahler - ricci flow converges to a conical k \ " ahler - einstein metric with cone angle $ 2 \ pi \ beta ' $ along the divisor. here, we only use the condition that the log mabuchi energy is bounded from below. this is a weaker condition than the properness that we have adopted to study the convergence before. as corollaries, we give parabolic proofs of donaldson ' s openness theorem and his existence conjecture for the conical k \ " ahler - einstein metrics with positive ricci curvatures. | arxiv:1903.07528 |
a predictive model for nanoparticle nucleation has not yet been successfully achieved. classical nucleation theory fails because the atomistic nature of the seed has to be considered since geometrical structure as well as stoichiometry do not always match the bulk values. we present a fully microscopic approach based on a first - principle study of aluminium oxide clusters. we have calculated stable structures of alxoy } and their associated thermodynamic properties. from these data, the chemical composition of a gas composed of aluminium and oxygen atoms can be calculated as a function of temperature, pressure, and aluminium to oxygen ratio. we demonstrate the accuracy of this approach in reproducing experimental results obtained with time resolved spectroscopy of a laser induced plasma from an al2o3 } target. we thus extended the calculation to lower temperatures, i. e. longer time scales, to propose a scenario of composition gas evolution leading to the first alumina seeds. | arxiv:1707.08434 |
the widespread application of artificial intelligence ( ai ) in various tasks, along with frequent reports of conflicts or violations involving ai, has sparked societal concerns about interactions with ai systems. based on wrightsman ' s philosophies of human nature scale ( phns ), a scale empirically validated over decades to effectively assess individuals ' attitudes toward human nature, we design the standardized psychological scale specifically targeting large language models ( llm ), named the machine - based philosophies of human nature scale ( m - phns ). by evaluating llms ' attitudes toward human nature across six dimensions, we reveal that current llms exhibit a systemic lack of trust in humans, and there is a significant negative correlation between the model ' s intelligence level and its trust in humans. furthermore, we propose a mental loop learning framework, which enables llm to continuously optimize its value system during virtual interactions by constructing moral scenarios, thereby improving its attitude toward human nature. experiments demonstrate that mental loop learning significantly enhances their trust in humans compared to persona or instruction prompts. this finding highlights the potential of human - based psychological assessments for llm, which can not only diagnose cognitive biases but also provide a potential solution for ethical learning in artificial intelligence. we release the m - phns evaluation code and data at https : / / github. com / kodenii / m - phns. | arxiv:2504.02304 |
in [ m. zych et al., nat. commun. 2, 505 ( 2011 ) ], the authors predicted that the interferometric visibility is affected by a gravitational field in way that cannot be explained without the general relativistic notion of proper time. in this work, we take a different route and start deriving the same effect using the unitary representation of the local lorentz transformation in the newtonian limit. in addition, we show that the effect on the interferometric visibility due to gravity persists in different spacetime geometries. however, the influence is not necessarily due to the notion of proper time. for instance, by constructing a ` astronomical ' mach - zehnder interferometer in the schwarzschild spacetime, the influence on the interferometric visibility can be due to another general relativistic effect, the geodetic precession. besides, by using the unitary representation of the local lorentz transformation, we show that this behavior of the interferometric visibility is general for an arbitrary spacetime, provided that we restrict the motion of the quanton to a two - dimensional spacial plane. | arxiv:2101.06320 |
in this paper we estimate a bayesian vector autoregressive model with factor stochastic volatility in the error term to assess the effects of an uncertainty shock in the euro area. this allows us to treat macroeconomic uncertainty as a latent quantity during estimation. only a limited number of contributions to the literature estimate uncertainty and its macroeconomic consequences jointly, and most are based on single country models. we analyze the special case of a shock restricted to the euro area, where member states are highly related by construction. we find significant results of a decrease in real activity for all countries over a period of roughly a year following an uncertainty shock. moreover, equity prices, short - term interest rates and exports tend to decline, while unemployment levels increase. dynamic responses across countries differ slightly in magnitude and duration, with ireland, slovakia and greece exhibiting different reactions for some macroeconomic fundamentals. | arxiv:1801.02925 |
we present high resolution simulations of a multiple merger of three disk galaxies including the evolution of magnetic fields performed with the n - body / sph code gadget. for the first time, we embed the galaxies in a magnetized, low - density medium, thus modeling an ambient igm. the simulations include radiative cooling and a model for star formation and supernova feedback. the progenitor disks have initial magnetic seed fields in the range of 10e - 9 to 10e - 6 g and the igm has initial fields of 10e - 12 to 10e - 9 g. the simulations are compared to a run excluding magnetic fields. we show that the propagation of interaction - driven shocks depends significantly on the initial magnetic field strength. the shocks propagate faster in simulations with stronger initial field, suggesting that the shocks are supported by magnetic pressure. the mach numbers of the shocks range from approximately m = 1. 5 for the non - magnetized case up to m = 6 for the highest initial magnetization, resulting in higher temperatures of the shock heated igm gas. the magnetic field in the system saturates rapidly after the mergers at ~ 10e - 6 g within the galaxies and ~ 10e - 8 g in the igm independent of the initial value. these field strengths agree with observed values and correspond to the equipartition value of the magnetic pressure with the turbulent pressure in the system. we also present synthetic radio and polarization maps for different phases of the evolution showing that shocks driven by the interaction produce a high amount of polarized emission. these idealized simulations indicate that magnetic fields play an important role for the hydrodynamics of the igm during galactic interactions. we also show that even weak seed fields are efficiently strengthened during multiple galactic mergers. this interaction driven amplification might have been a key process for the magnetization of the universe. | arxiv:1011.5735 |
achieving the no - regret property for reinforcement learning ( rl ) problems in continuous state and action - space environments is one of the major open problems in the field. existing solutions either work under very specific assumptions or achieve bounds that are vacuous in some regimes. furthermore, many structural assumptions are known to suffer from a provably unavoidable exponential dependence on the time horizon $ h $ in the regret, which makes any possible solution unfeasible in practice. in this paper, we identify local linearity as the feature that makes markov decision processes ( mdps ) both learnable ( sublinear regret ) and feasible ( regret that is polynomial in $ h $ ). we define a novel mdp representation class, namely locally linearizable mdps, generalizing other representation classes like linear mdps and mdps with low inherent belmman error. then, i ) we introduce cinderella, a no - regret algorithm for this general representation class, and ii ) we show that all known learnable and feasible mdp families are representable in this class. we first show that all known feasible mdps belong to a family that we call mildly smooth mdps. then, we show how any mildly smooth mdp can be represented as a locally linearizable mdp by an appropriate choice of representation. this way, cinderella is shown to achieve state - of - the - art regret bounds for all previously known ( and some new ) continuous mdps for which rl is learnable and feasible. | arxiv:2410.24071 |
different descriptions used to model a point - defect in an elastic continuum are reviewed. the emphasis is put on the elastic dipole approximation, which is shown to be equivalent to the infinitesimal eshelby inclusion and to the infinitesimal dislocation loop. knowing this elastic dipole, a second rank tensor fully characterizing the point - defect, one can directly obtain the long - range elastic field induced by the point - defect and its interaction with other elastic fields. the polarizability of the point - defect, resulting from the elastic dipole dependence with the applied strain, is also introduced. parameterization of such an elastic model, either from experiments or from atomic simulations, is discussed. different examples, like elastodiffusion and bias calculations, are finally considered to illustrate the usefulness of such an elastic model to describe the evolution of a point - defect in a external elastic field. | arxiv:1802.04062 |
we present examples of color hopf algebras, i. e. hopf algebras in color categories ( braided tensor categories with braiding induced by a bicharacter on an abelian group ), related with quantum doubles of pointed hopf algebras. we also discuss semisimple color hopf algebras. | arxiv:1212.0514 |
it shown that any coideal subalgebra of a finite dimensional hopf algebra is a cyclic module over the dual hopf algebra. using this we describe all coideal subalgebras of a cocentral abelian extension of hopf algebras extending some results from [ 4 ]. | arxiv:1203.5491 |
we present a preliminary laboratory test of a setup designed to measure hanbury brown and twiss - type intensity correlations from a chaotic light source using five spectral channels simultaneously. after averaging the zero - delay correlation peaks from all channels, we obtain an improvement of the signalto - noise ratio fairly consistent with theory. the goal is to demonstrate the feasibility and scalability of this technique to improve the sensitivity of stellar intensity interferometry using optical telescopes. | arxiv:2411.08417 |
in this paper we generalize cellular algebras by allowing different partial orderings relative to fixed idempotents. for these relative cellular algebras we classify and construct simple modules, and we obtain other characterizations in analogy to cellular algebras. we also give several examples of algebras that are relative cellular, but not cellular. most prominently, the restricted enveloping algebra and the small quantum group for $ \ mathfrak { sl } _ { 2 } $, and an annular version of arc algebras. | arxiv:1710.02851 |
this paper proposes a new mathematical approach to characterize native protein structures based on the discrete differential geometry of tetrahedron tiles. in the approach, local structure of proteins is classified into finite types according to shape. and one would obtain a number sequence representation of protein structures automatically. as a result, it would become possible to quantify structural preference of amino - acids objectively. and one could use the wide variety of sequence alignment programs to study protein structures since the number sequence has no internal structure. the programs and this paper with clear figures are available from http : / / www. genocript. com. | arxiv:q-bio/0610017 |
large language models ( llms ) often struggle with complex logical reasoning due to logical inconsistencies and the inherent difficulty of such reasoning. we use lean, a theorem proving framework, to address these challenges. by formalizing logical reasoning problems into theorems within lean, we can solve them by proving or disproving the corresponding theorems. this method reduces the risk of logical inconsistencies with the help of lean ' s symbolic solver. it also enhances our ability to treat complex reasoning tasks by using lean ' s extensive library of theorem proofs. our method achieves state - of - the - art performance on the folio dataset and achieves performance near this level on proofwriter. notably, these results were accomplished by fine - tuning on fewer than 100 in - domain samples for each dataset. | arxiv:2403.13312 |
in this paper, we prove that hitting probability of minkowski sum of fractal percolations can be characterized by capacity. then we extend this result to minkowski sum of general random sets in $ \ mathbb z ^ d $, including ranges of random walks and critical branching random walks, whose hitting probabilities are described by newtonian capacity individually. | arxiv:2412.16415 |
a common way of stating the non - cloning theorem - - one of distinguishing characteristics of quantum theory - - is that one cannot make a copy of an arbitrary unknown quantum state. even though this theorem is an important part of the ongoing discussion of the nature of a quantum state, the role of the theorem in the logical - algebraic approach to quantum theory has not yet been systematically studied. according to the standard point of view ( which is in line with the logical tradition ), quantum cloning amounts to two classical rules of inference, namely, monotonicity and idempotency of entailment. one can conclude then that the whole of quantum theory should be described through a logic wherein these rules do not hold, which is linear logic. however, in accordance with a supervaluational semantics ( that allows one to retain all the theorems of classical logic while admitting ` truth - value gaps ' ), quantum cloning necessitates the permanent loss of the truth values of experimental quantum propositions which violates the unalterability of the past. the present paper demonstrates this. | arxiv:1905.06766 |
we show that the space charge dynamics of high intensity beams in the plane perpendicular to the magnetic field in cyclotrons is described by the two - dimensional euler equations for an incompressible fluid. this analogy with fluid dynamics gives a unified and intuitive framework to explain the beam spiraling and beam break up behavior observed in experiments and in simulations. in particular, we demonstrate that beam break up is the result of a classical instability occurring in fluids subject to a sheared flow. we give scaling laws for the instability and predict the nonlinear evolution of beams subject to it. our work suggests that cyclotrons may be uniquely suited for the experimental study of shear layers and vortex distributions that are not achievable in penning - malmberg traps. | arxiv:1604.04323 |
we present a multi - scale spiking network model of all vision - related areas of macaque cortex that represents each area by a full - scale microcircuit with area - specific architecture. the layer - and population - resolved network connectivity integrates axonal tracing data from the cocomac database with recent quantitative tracing data, and is systematically refined using dynamical constraints. simulations reveal a stable asynchronous irregular ground state with heterogeneous activity across areas, layers, and populations. elicited by large - scale interactions, the model reproduces longer intrinsic time scales in higher compared to early visual areas. activity propagates down the visual hierarchy, similar to experimental results associated with visual imagery. cortico - cortical interaction patterns agree well with fmri resting - state functional connectivity. the model bridges the gap between local and large - scale accounts of cortex, and clarifies how the detailed connectivity of cortex shapes its dynamics on multiple scales. | arxiv:1511.09364 |
using quantum monte carlo simulations, we study a series of models of fermions coupled to quantum ising spins on a square lattice with $ n $ flavors of fermions per site for $ n = 1, 2 $ and $ 3 $. the models have an extensive number of conserved quantities but are not integrable, and have rather rich phase diagrams consisting of several exotic phases and phase transitions that lie beyond landau - ginzburg paradigm. in particular, one of the prominent phase for $ n > 1 $ corresponds to $ 2n $ gapless dirac fermions coupled to an emergent $ \ mathbb { z } _ 2 $ gauge field in its deconfined phase. however, unlike a conventional $ \ mathbb { z } _ 2 $ gauge theory, we do not impose the ` gauss ' s law ' by hand and instead, it emerges due to spontaneous symmetry breaking. correspondingly, unlike a conventional $ \ mathbb { z } _ 2 $ gauge theory in two spatial dimensions, our models have a finite temperature phase transition associated with the melting of the order parameter that dynamically imposes the gauss ' s law constraint at zero temperature. by tuning a parameter, the deconfined phase undergoes a transition into a short range entangled phase, which corresponds to n \ ' eel / superconductor for $ n = 2 $ and a valence bond solid for $ n = 3 $. furthermore, for $ n = 3 $, the valence bond solid further undergoes a transition to a n \ ' eel phase consistent with the deconfined quantum critical phenomenon studied earlier in the context of quantum magnets. | arxiv:1607.03912 |
we analyze the x - ray spectra and their timing properties of the compact x - ray binary 4u ~ 1820 - 30. we establish a number of spectral transitions in this source seen with bepposax and rxte. during the rxte observations ( 1996 - - 2009 ), the source were approximately 75 % of its time in the soft state making the lower banana and upper banana transitions combined with long - term low - high state transitions. we reveal that all of the x - ray spectra of 4u ~ 1820 - 30 are fit by a composition of a thermal ( blackbody ) component, a comptonization component ( comptb ) and a gaussian - line component. thus using this spectral analysis we find that the photon power - law index gamma of the comptonization component is almost unchangeable ( gamma ~ 2 ) while the electron temperature kt _ e changes from 2. 9 to 21 kev during these spectral events. we also establish that for these spectral events the normalization of comptb component ( which is proportional to mass accretion rate, \ dot m increases by factor 8 when kt _ e decreases from 21 kev to 2. 9 kev. before this index stability effect was also found analyzing x - ray data for z - source gx 340 + 0 and for atolls, 4u ~ 1728 - 34, gx ~ 3 + 1. thus, we can suggest that this spectral stability property is a spectral signature of an accreting neutron star source. on the other hand in a black hole binary gamma monotonically increases with \ dot m and ultimately its value saturates at large \ dot m. | arxiv:1303.4323 |
we describe how to apply the transport method to compute inflationary observables in a broad range of multiple - field models. the method is efficient and encompasses scenarios with curved field - space metrics, violations of slow - roll conditions and turns of the trajectory in field space. it can be used for an arbitrary mass spectrum, including massive modes and models with quasi - single - field dynamics. in this note we focus on practical issues. it is accompanied by a mathematica code which can be used to explore suitable models, or as a basis for further development. | arxiv:1502.03125 |
we investigate nonperturbatively the effect of a magnetic dopant impurity on the edge transport of a quantum spin hall ( qsh ) insulator. we show that for a strongly coupled magnetic dopant located near the edge of a system, a pair of transmission anti - resonances appear. when the chemical potential is on resonance, interaction effects broaden the anti - resonance width with decreasing temperature, thus suppressing transport for both repulsive and moderately attractive interactions. consequences for the recently observed qsh insulating phase of the $ 1 $ - t $ ^ { \ prime } $ of wte $ _ 2 $ are briefly discussed. | arxiv:1609.06227 |
recently, bocklandt proved a conjecture by van den bergh in its graded version, stating that a graded quiver algebra ( with relations ) which is calabi - yau of dimension 3 is defined from a homogeneous potential w. in this paper, we prove that if we add to w any potential of smaller degree, we get a poincare - birkhoff - witt deformation of a. such pbw deformations are calabi - yau and are characterised among all the pbw deformations of a. various examples are presented. | arxiv:math/0610112 |
when a binary fluid demixes under a slow temperature ramp, nucleation, coarsening and sedimentation of droplets lead to an oscillatory evolution of the phase separating system. the advection of the sedimenting droplets is found to be chaotic. the flow is driven by density differences between the two phases. here, we show how image processing can be combined with particle tracking to resolve droplet size and velocity simultaneously. droplets are used as tracer particles, and the sedimentation velocity is determined. taking these effects into account, droplets with radii in the range of 4 - - 40 micrometers are detected and tracked. based on this data we resolve the oscillations in the droplet size distribution which are coupled to the convective flow. | arxiv:1107.1194 |
##phisms from x to x are precisely the elements of the monoid, the identity morphism of x is the identity of the monoid, and the categorical composition of morphisms is given by the monoid operation. several definitions and theorems about monoids may be generalized for categories. similarly any group can be seen as a category with a single object in which every morphism is invertible, that is, for every morphism f there is a morphism g that is both left and right inverse to f under composition. a morphism that is invertible in this sense is called an isomorphism. a groupoid is a category in which every morphism is an isomorphism. groupoids are generalizations of groups, group actions and equivalence relations. actually, in the view of category the only difference between groupoid and group is that a groupoid may have more than one object but the group must have only one. consider a topological space x and fix a base point x 0 { \ displaystyle x _ { 0 } } of x, then π 1 ( x, x 0 ) { \ displaystyle \ pi _ { 1 } ( x, x _ { 0 } ) } is the fundamental group of the topological space x and the base point x 0 { \ displaystyle x _ { 0 } }, and as a set it has the structure of group ; if then let the base point x 0 { \ displaystyle x _ { 0 } } runs over all points of x, and take the union of all π 1 ( x, x 0 ) { \ displaystyle \ pi _ { 1 } ( x, x _ { 0 } ) }, then the set we get has only the structure of groupoid ( which is called as the fundamental groupoid of x ) : two loops ( under equivalence relation of homotopy ) may not have the same base point so they cannot multiply with each other. in the language of category, this means here two morphisms may not have the same source object ( or target object, because in this case for any morphism the source object and the target object are same : the base point ) so they can not compose with each other. any directed graph generates a small category : the objects are the vertices of the graph, and the morphisms are the paths in the graph ( augmented with loops as needed ) where composition of morphisms is concatenation of paths. such a category is called the free category | https://en.wikipedia.org/wiki/Category_(mathematics) |
the manufacture of solid oxide fuel cells ( sofcs ) involves fabrication of a multilayer ceramic structure, for which constrained sintering is a key processing step in many cases. defects are often observed in the sintered structure, but their formation during sintering is not well understood. in this work, various ceramic films were fabricated by screen printing and a variety of defects observed. some films showed mud - cracking defects, whereas others presented distributed large pores. mud cracking defects were found to originate from a network of fine cracks present in the green film and formed during drying and binder burn - out. control of these early stages is essential for producing crack - free films. in order to investigate how defects evolve during sintering, artificial cracks were introduced in the green films using indentation. it was observed that crack opening always increased during constrained sintering. in contrast, similar initial cracks could be closed and healed during co - sintering. | arxiv:1502.01878 |
in this paper, parallel interconnection of dc / dc converters is considered. for this topology of converters feeding a common load, it has been recently shown that dynamics related to voltage regulation can be completely separated from the current distribution without considering frequency separation arguments, which inevitably limits achievable performance. within the hamiltonian framework, this paper shows that this separation between current distribution and voltage regulation is linked to the energy conservative quantities : the casimir functions. furthermore, a robust control law is given in this framework to get around the fact that the load might be unknown. in this paper, we also ensure that the system converges to the optimal current repartition, without requiring explicit expression of the optimal locus. finally, resulting control law efficiency is assessed through experimental results. | arxiv:1912.07703 |
in this work, we present an analysis of sne number ratios in spiral galaxies with different morphological subtypes, luminosities, ssfr, and metallicities, to provide important information about the physical properties of the progenitor populations. | arxiv:1312.5896 |
in the present paper we consider multi - scalar extension of einstein - gauss - bonnet gravity. we focus on multi - scalar einstein - gauss - bonnet models whose target space is a three - dimensional maximally symmetric space, namely either $ \ mathbb { s } ^ 3 $, $ \ mathbb { h } ^ 3 $ or $ \ mathbb { r } ^ 3 $, and in the case when the map $ \ text { \ it spacetime } \ to \ text { \ it target space } $ is nontrivial. we prove numerically the existence of black holes in this class of models for several gauss - bonnet coupling functions, including the case of scalarization. we also perform systematic study of a variety of black hole characteristics and the space - time around them, such as the area of the horizon, the entropy and the radius of the photon sphere. one of the most important properties of the obtained solutions is that the scalar charge is zero and thus the scalar dipole radiation is suppressed which leads to much weaker observational constraints compared to the majority of modified theories possessing a scalar degree of freedom. for one of the coupling functions we could find branches of scalarized black holes which have a nontrivial structure - - there is non - uniqueness of the scalarized solutions belonging to a single branch and there is a region of the parameter space where most probably stable scalarized black holes coexist with the stable schwarzschild black holes. such a phenomena can have a clear observational signature. | arxiv:2006.11515 |
we calculate the change in the correlation gap of armchair carbon nanotubes with uniaxial elastic strain. we predict that such a stretching will enlarge the correlation gap for all carbon nanotubes by a change that could be as large as several mev per percent of applied strain, in contrast with pure band structure calculations where no change for armchair carbon nanotubes is predicted. the correlation effects are considered within a self - consistent hartree - fock approximation to the hubbard model with on - site repulsion only. | arxiv:cond-mat/0310282 |
in this paper we address the following question regarding the regularity of geodesics in the space of k \ " ahler potentials. given a geodesic which is highly regular, and has smooth boundary value, can we expect that it is actually smooth? we construct an example to show that the answer to the question is ` ` no ". | arxiv:1808.03498 |
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