1,475 research outputs found

    Local and Global Properties of the World

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    The essence of the method of physics is inseparably connected with the problem of interplay between local and global properties of the universe. In the present paper we discuss this interplay as it is present in three major departments of contemporary physics: general relativity, quantum mechanics and some attempts at quantizing gravity (especially geometrodynamics and its recent successors in the form of various pregeometry conceptions). It turns out that all big interpretative issues involved in this problem point towards the necessity of changing from the standard space-time geometry to some radically new, most probably non-local, generalization. We argue that the recent noncommutative geometry offers attractive possibilities, and gives us a conceptual insight into its algebraic foundations. Noncommutative spaces are, in general, non-local, and their applications to physics, known at present, seem very promising. One would expect that beneath the Planck threshold there reigns a ``noncommutative pregeometry'', and only when crossing this threshold the usual space-time geometry emerges.Comment: 43 pages, latex, no figures, changes: authors and abstract added to the body of pape

    Le déterminisme du hasard : Quelques exemples tirés de la théorie des graphes et des paysages

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    Au lieu d’un concept de hasard impossible Ă  cerner, ne pourrait-on pas se risquer Ă  dire qu’il existe plutĂŽt une variĂ©tĂ© de dĂ©terminismes, ceux-ci Ă©tant plus ou moins « souples », c’est-Ă -dire prĂ©sentant plus ou moins de contraintes, de rĂ©gularitĂ©s. Le concept de hasard serait alors purement relatif, au sens oĂč il n’existerait pas une notion absolue de hasard, mais une pluralitĂ© de significations du concept de « dĂ©terminisme ».Instead of a concept of chance impossible to define, could we not risk the idea that there are rather a variety of determinisms, the latter being more or less flexible, that is to say presenting more or less constraints, or regularities. The concept of chance would then be purely relative, in the sense that there would be no absolute notion of chance but a plurality of meanings of the concept of “determinism”

    Is it what you inherited or what you learnt ? Intergenerational linkage and interpersonal inequality in Senegal

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    Institutional features of the African setting -- large extended families and imperfect credit and land markets -- matter to the equity and efficiency roles played by intergenerational linkages. Using original survey data on Senegal that include an individualized measure of consumption, this paper studies the role played by land inheritance, other bequests and parental background as influences on an adult's economic welfare and economic activities. Although intergenerational linkages are evident, the analysis finds a seemingly high degree of mobility across generations, associated with the shift from farm to non-farm sectors and the greater economic activity of women. Male-dominated bequests of land and housing bring little gain to mean consumption and play little role in explaining inequality, although they have effects on the sector of activity. Inheritance of non-land assets and the education and occupation of parents (especially the mother) and their choices about children's schooling are more important to adult welfare than property inheritance. Significant gender inequality in consumption is evident, although it is almost entirely explicable in terms of factors such as education and (non-land) inheritance. There are a number of other pronounced gender differences, with intergenerational linkages coming through the mother rather than the father.Population Policies,Gender and Law,Agricultural Knowledge&Information Systems,Rural Development Knowledge&Information Systems,Gender and Health

    A micro-decomposition analysis of the macroeconomic determinants of human development

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    This paper shows how differences in aggregate human development outcomes over time and space can be additively decomposed into a pure economic-growth component, a component attributed to differences in the distribution of income, and components attributed to"non-income"factors and differences in the model linking outcomes to income or non-income characteristics. The income effect at the micro level is modeled non-parametrically, so as to flexibly reflect distributional changes. The paper illustrates the decomposition using data for Morocco and Vietnam, and the results offer some surprising insights into the observed aggregate gains in schooling attainments. A user friendly STATA program is available to implement the method in other settings.Primary Education,Education For All,Population Policies,Rural Poverty Reduction,Inequality

    From contradiction to conciliation:a way to "dualize" sheaves

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    Our aim is to give some insights about how to approach the formal description of situations where one has to conciliate several contradictory statements, rules, laws or ideas. We show that such a conciliation structure can be naturally defined on a topological space endowed with the set of its closed sets and that this specific structure is a kind of "dualization" of the sheaf concept where "global" and "local" levels are reversed

    Bases de données séquentielles et méthodes inverses appliquées au CND par courants de Foucault.

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    1pLe but de cette étude est de développer une méthode d'optimisation capable, en temps réel, de donner un résultat fiable de ContrÎle Non Destructif par Courants de Foucault (CND-CF). On utilise des bases de données séquentielles à partir desquelles il est possible de générer des données par interpolation tout en maßtrisant l'erreur maximale d'interpolation. Ces bases de données sont ensuite utilisées avec des méthodes d'optimisation afin de résoudre le problÚme de CND. D'une part, elles servent à générer rapidement des signaux utilisés par des méthodes d'optimisation particulaires, ici le PSO (Particle Swarm Optimizer). Cela permet d'accélérer considérablement la méthode PSO avec en contrepartie une perte en précision due à l'interpolation. D'autre part, elles sont utilisées comme bases d'apprentissage pour une méthode d'inversion par SVM (Support Vectors Machines). On obtient ainsi deux méthodes rapides, l'une particulaire et l'autre par apprentissage, permettant de mesurer les dimensions des défauts que l'on désire retrouver. Des premiers résultats sont exposés et les deux méthodes d'inversion sont comparées

    Particle optimization with metamodel for crack characterization

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    International audienceA new inverse method for real time eddy current testing is introduced. It is based on particle swarm optimization coupled with a metamodel. This metamodel is generated by interpolating data from an adaptive database. Linear and radial basis function interpolations are compared as means to generate the metamodel. The inverse method gives a result combined with an approximation of the likelihood function to help for decision analysis. It is finally compared to a state-of-art inverse method using support vector machine on a 3D case on simulated data with very promising results

    Determination of five folate monoglutamates in rodent diets

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    A method for the quantitative determination of folates in rodent diets is very important for correct interpretation of folate intake during feeding trials, given the possible discrepancy between the actual folate concentration in the diet and that mentioned on the product sheet. Liquid chromatography tandem-mass spectrometry is the method of choice to differentiate and quantify the individual folate species present. This discrepancy may be accounted for by, e.g., inaccurate folic acid supplementation and/or the presence of endogenous reduced and substituted folates. We developed a method, validated based on FDA guidelines, that allows the measurement of added and endogenous folates by quantitative determination of 5 folate monoglutamates with linear ranges from 8 mu g to 2 mg/kg feed. This information, combined with feed intake data, allows insight into the actual folate intake in animal feeding studies. The relevance of this method was illustrated by the analysis of several feed samples of varying composition, by the investigation of the effect of casein incorporation, and by evaluating the variability of the folate content between pellets and production batches
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