6,135 research outputs found

    Component-based simulation for a reconfiguration study of transitic systems

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    This paper is organized as follows. Part A presents the context of reconfiguring transitic systems and the main idea in implementing the decision step. It comprises sections 1 to 3. Section 3 presents an example that illustrates the concepts presented in the next sections. Parts B and C express the models and principles used to simulate transitic systems, the result of which will be helpful for choosing the new configuration. Part B focuses mainly on models. It comprises sections 4 to 6. Part C focuses mainly on simulation principles. It comprises sections 7 to 10

    Creep and depinning in disordered media

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    Elastic systems driven in a disordered medium exhibit a depinning transition at zero temperature and a creep regime at finite temperature and slow drive ff. We derive functional renormalization group equations which allow to describe in details the properties of the slowly moving states in both cases. Since they hold at finite velocity vv, they allow to remedy some shortcomings of the previous approaches to zero temperature depinning. In particular, they enable us to derive the depinning law directly from the equation of motion, with no artificial prescription or additional physical assumptions. Our approach provides a controlled framework to establish under which conditions the depinning regime is universal. It explicitly demonstrates that the random potential seen by a moving extended system evolves at large scale to a random field and yields a self-contained picture for the size of the avalanches associated with the deterministic motion. At T>0T>0 we find that the effective barriers grow with lenghtscale as the energy differences between neighboring metastable states, and demonstrate the resulting activated creep law vexp(Cfμ/T)v\sim \exp (-C f^{-\mu}/T) where the exponent μ\mu is obtained in a ϵ=4D\epsilon=4-D expansion (DD is the internal dimension of the interface). Our approach also provides quantitatively a new scenario for creep motion as it allows to identify several intermediate lengthscales. In particular, we unveil a novel ``depinning-like'' regime at scales larger than the activation scale, with avalanches spreading from the thermal nucleus scale up to the much larger correlation length RVR_{V}. We predict that RVTσfλR_{V}\sim T^{-\sigma}f^{-\lambda } diverges at small ff and TT with exponents σ,λ\sigma ,\lambda that we determine.Comment: 29 pages, 14 figures, RevTex, one figure adde

    Macrophage Migration Inhibitory Factor: Gene Polymorphisms and Susceptibility to Inflammatory Diseases

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    The cytokine macrophage migration inhibitory factor (MIF) is a constitutive element of the host antimicrobial defenses and stress response that promotes proinflammatory function of the innate and acquired immune systems. MIF plays an important role in the pathogenesis of acute and chronic inflammatory or autoimmune disorders, such as sepsis, acute respiratory distress syndrome, asthma, rheumatoid arthritis, and inflammatory bowel diseases. Polymorphisms of the humanMIF gene (that is, guanine-to-cytosine transition at position -173 or CATT-tetranucleotide repeat at position -794) have been associated with increased susceptibility to or severity of juvenile idiopathic and adult rheumatoid arthritis, ulcerative colitis, atopy, or sarcoidosis. Whether theseMIF polymorphisms affect the susceptibility to and outcome of sepsis has not yet been examined. Analyses ofMIF genotypes in patients with sepsis may help to classify patients into risk categories and to identify those patients who may benefit from anti-MIF therapeutic strategie

    Riesz transform on manifolds and heat kernel regularity

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    One considers the class of complete non-compact Riemannian manifolds whose heat kernel satisfies Gaussian estimates from above and below. One shows that the Riesz transform is LpL^p bounded on such a manifold, for pp ranging in an open interval above 2, if and only if the gradient of the heat kernel satisfies a certain LpL^p estimate in the same interval of pp's.Comment: to appear in Annales de l'Ecole Normale Superieure de Pari

    Relation Structure moléculaire - Odeur Utilisation des Réseaux de Neurones pour l’estimation de l’Odeur Balsamique

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    Les molécules odorantes (parfums ou flaveurs) sont utilisées dans une grande variété de produits de consommation, pour inciter les consommateurs à associer les impressions favorables à un produit donné. La Relation Structure moléculaire-Odeur (SOR) est cruciale pour la synthèse de ces molécules mais est très difficile à établir due à la subjectivité de l’odeur. Ce travail présente une approche de prédiction de l'odeur des molécules basée sur les descripteurs moléculaires. Les techniques d’analyse en composantes principales (PCA) et de d’analyse de colinéarité permettent d’identifier les descripteurs les plus pertinents. un réseau de neurones supervisé5 à deux couches (cachée et sortie) est employé pour corréler la structure moléculaire à l’odeur. La base de données décrite précédemment est utilisée pour l’apprentissage. Un ensemble de paramètres est modifié jusqu’à la satisfaction de la meilleure régression. Les résultats obtenus sont encouragent, ainsi les descripteurs moléculaires convenables corrèlent efficacement l'odeur des molécules. C’est la première étape d’un modèle générique en développement pour corréler l'odeur avec les structures moléculaire

    Comparative analysis between impact factor and h-index for psychiatry journals

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    International audienceObjective: Journal Impact Factor (IF) is well known for being the document measure of scientific journal impact, despite several recognised limitations. Our study tried to propose a new rating system (journal h-index) applied to a sample of psychiatry journals and compared to IF. Method: In order to strictly compare their IF and h-index using the same data, we wanted to work on all the citations obtained in 2006 by the articles published in 2004-2005 in the 50 journals of our Web of Science sample of psychiatry. We studied the statistical correlation between the IF 2006 and h-index 2006. Results: The rankings of the 50 psychiatry journals were different when we took into account respectively the descending order of IF 2006 and h-index 2006 which revealed 16 steps and therefore 16 groups of journals. We noted that two journals were up 21 places (record) in h-index 2006 ranking and one journal lost 17 places. Nevertheless we obtained a high correlation coefficient well illustrated by the group of the seven first journals whose the two rankings were very close. We noted that our sample had only two journals really specialised in the publication of reviews. Conclusions: The rating of journals starting from the h-index may represent an interesting and complementary alternative to the well-known rating based on the IF. The h-index rating proposes a categorization of journals making it possible to create classes of journals with the same h-index. This type of ranking by classes is often appreciated and used by experts and scientific committees of evaluation

    Comparative analysis between impact factor and h-index for pharmacology and psychiatry journals

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    International audienceUsing strictly the same parameters (identical two publication years (2004-2005) and identical one-year citation window (2006)), IF 2006 was compared with h-index 2006 for two samples of "Pharmacology and Pharmacy" and "Psychiatry" journals computed from the ISI Web of Science. For the two samples, the IF and the h-index rankings of the journals are very different. The correlation coefficient between the IF and the h-index is high for Psychiatry but lower for Pharmacology. The linearity test performed between the h-index and showed the great sensitivity of the model compared with . The IF and h-index can be completely complementary when evaluating journals of the same scientific discipline
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