6,995 research outputs found

    Well-posedness for the fifth-order KdV equation in the energy space

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    We prove that the initial value problem (IVP) associated to the fifth order KdV equation {equation} \label{05KdV} \partial_tu-\alpha\partial^5_x u=c_1\partial_xu\partial_x^2u+c_2\partial_x(u\partial_x^2u)+c_3\partial_x(u^3), {equation} where x∈Rx \in \mathbb R, t∈Rt \in \mathbb R, u=u(x,t)u=u(x,t) is a real-valued function and α, c1, c2, c3\alpha, \ c_1, \ c_2, \ c_3 are real constants with α≠0\alpha \neq 0, is locally well-posed in Hs(R)H^s(\mathbb R) for s≄2s \ge 2. In the Hamiltonian case (\textit i.e. when c1=c2c_1=c_2), the IVP associated to \eqref{05KdV} is then globally well-posed in the energy space H2(R)H^2(\mathbb R).Comment: We corrected a few typos and fixed a technical mistake in the proof of Lemma 6.3. We also changed a comment on the work of Guo, Kwak and Kwon on the same subject according to the new version they posted recently on the arXiv (arXiv:1205.0850v2

    Dextran sulfate enhances the level of an oxidative DNA damage biomarker, 8-oxo-7,8-dihydro-2 0-deoxyguanosine, in rat colonic mucosa

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    Dextran sodium sulfate (DSS) given in drinking water can induce colonic Inflammation and produce colorectal tumors in rodents, although it is not directly genotoxic. The hypothesis that DSS can produce free radicals and induce oxidative DNA damage in colonic mucosa has been tested. In rats fed for 2 days with water containing 3% and 6% DSS, colonic Inflammation manifestations were recorded and 8-oxo-7,8-dihydro-2 0-deoxyguanosine (8-oxodGuo), a major biomarker of oxidative DNA damage, was assayed in colonic mucosa. As compared with control rats given pure water, inflammatory manifestations were seen in rats given DSS. At the same time, 8-oxodGuo levels in colonic mucosa were doubled (P , 0:001). These results suggest that formation of oxidative DNA damage in colonic mucosa depends on inflammation and maybe on the production of reactive oxygen species. This study shows that DSS can induce oxidative DNA damage within only 2 days, which could explain in part its carcinogenic properties

    SPOT 4 space magnetic recorder mechanisms

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    The design of the SPOT 4 satellite will be quite different from the previous ones. The design of the new magnetic tape recorder, which was derived from industrial knowledge and mission requirements; the main technical characteristics of the recorder; and the mechanical subsystems of the recorder and their locations and contributions to the final performance are all discussed. The philosophy of the development program, required to achieve the desired performance and reliability for each flight model, is described, and information on the schedule and current development is presented. The components of the tape plate system, (the transmission belts, tape rollers of the recorders, and reel hub ball bearings) which are subjected to heavy mechanical operation, fatigue, and wear in the thermal environment of the mission, are discussed. For each of the components, a description of its function in the recorder is given, as well as the mechanical stress imposed during the various operational phases. The quality testing program, which was used to verify the design safety margins, is described. Finally, the first test results of a functioning model of the flight system are presented

    Coordination sécurité pour la phase génie civil du projet LHC

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    Partant des constatations que le risque d'accident est deux fois plus important dans le BTP que dans les autres branches d'activité et que 60% des accidents dans le BTP proviennent de choix effectués avant travaux, une directive européenne a été élaborée et a donné naissance à des textes de loi français. La principale mesure résultant de ces textes est la désignation, par le maßtre d'ouvrage d'un coordonnateur sécurité. Ce coordonnateur est chargé, entre autres, de prévenir les risques de coactivités des entreprises. Il intervient dÚs la phase de conception en vue d'analyser et de prévenir les risques sur le chantier et dans les interventions ultérieures. Les textes de loi décrivent également les notions de déclarations préalables, aux autorités compétentes, les plans de sécurité rédigés par le coordonnateur et les entreprises, ainsi que le dossier rassemblant les éléments utiles en matiÚre de sécurité et de santé pour d'éventuels travaux ultérieurs. Toutes ces dispositions sont mises en application par le groupe Génie civil du CERN pour la réalisation des ouvrages du projet LHC

    Ultra-low phase noise all-optical microwave generation setup based on commercial devices

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    In this paper, we present a very simple design based on commercial devices for the all-optical generation of ultra-low phase noise microwave signals. A commercial, fibered femtosecond laser is locked to a laser that is stabilized to a commercial ULE Fabry-Perot cavity. The 10 GHz microwave signal extracted from the femtosecond laser output exhibits a single sideband phase noise L(f)=−104 dBc/Hz\mathcal{L}(f)=-104 \ \mathrm{dBc}/\mathrm{Hz} at 1 Hz Fourier frequency, at the level of the best value obtained with such "microwave photonics" laboratory experiments \cite{Fortier2011}. Close-to-the-carrier ultra-low phase noise microwave signals will now be available in laboratories outside the frequency metrology field, opening up new possibilities in various domains.Comment: 8 pages, 3 figures. To be published in Applied Optics, early posting version available at http://www.opticsinfobase.org/ao/upcoming_pdf.cfm?id=23114

    Nitrogen-fixing stem nodules on Aeschynomene afraspera

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    PrĂ©sentation d'#Aeschynomene Afraspera qui est une lĂ©gumineuse tropicale qui se caractĂ©rise par de nombreuses nodulations sur la tige, fixateur d'azote. GrĂące Ă  ce potentiel de fixateur d'azote, #Aeschynomene Afraspera pourrait ĂȘtre utilisĂ© en tant qu'engrais vert pour la rizicultur

    De la quĂȘte de lĂ©gitimation Ă  la question de la lĂ©gitimitĂ© : les thĂ©rapeutiques "traditionnelles" au SĂ©nĂ©gal

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    E. Fassin & D. Fassin — From the Quest for Legitimation to the Question of Legitimacy : 'Traditional' Therapies in Senegal. The quest for new forms of recognition for traditional therapists raises the question of the relations between the different kinds of medical practices and, more precisely, that of medical legitimacy. Through three case studies carried out in Senegal, the authors attempt to show how principles of legitimation are defined today with, as essential characteristics: recognition of the least legitimate of the healers, strengthening of the legitimator's authority, and recourse to legitimating bodies outside of the medical field. This analysis shows the inanity of the classical modem/traditional opposition and leads to an examination of the meaning of a legitimacy crisis which seems to affect both doctors and healers.Fassin Éric, Fassin Didier. De la quĂȘte de lĂ©gitimation Ă  la question de la lĂ©gitimitĂ© : les thĂ©rapeutiques « traditionnelles » au SĂ©nĂ©gal.. In: Cahiers d'Ă©tudes africaines, vol. 28, n°110, 1988. pp. 207-231
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