2,275 research outputs found

    First results from the Trondheim Norway momentum-flux meteor radar

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    第3回極域科学シンポジウム 横断セッション「中層大気・熱圏」 11月26日(月) 国立極地研究所 2階大会議

    Supersymmetric solutions of N=2 d=4 sugra: the whole ungauged shebang

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    In this article we complete the classification of the supersymmetric solutions of N=2 D=4 ungauged supergravity coupled to an arbitrary number of vector- and hypermultiplets. We find that in the timelike case the hypermultiplets cause the constant-time hypersurfaces to be curved and have su(2) holonomy identical to that of the hyperscalar manifold. The solutions have the same structure as without hypermultiplets but now depend on functions which are harmonic in the curved 3-dimensional space. We discuss an example obtained from a hyper-less solution via the c-map. In the null case we find that the hyperscalars can only depend on the null coordinate and the solutions are essentially those of the hyper-less case.Comment: 27 pages, latex2

    Mécanismes de précipitation de carbonate de calcium dans les biofilms photosynthétiques

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    La précipitation de carbonate de calcium dans les systèmes benthiques est souvent associée aux biofilms photosynthétiques, et notamment observée au sein de structures d'une grande complexité morphologique comme les tapis microbiens, les stromatolithes et les microbialithes. Cette biocalcification modifie les flux de CO2, de calcium et d'alcalinité dans les hydrosystèmes (séquestration du carbone inorganique et d'alcalinité). Ce processus paraît donc très sensible aux impacts anthropiques, e.g. la perturbation globale du cycle du carbone et les contaminations atmosphériques. Son étude revêt une importance capitale pour la compréhension des paléoenvironnements. Différentes hypothèses ont été avancées pour expliquer la biocalcification dans ces biofilms. L'activité photosynthétique des cyanobactéries est souvent mise en cause, mais ce mécanisme est parfois contesté, privilégiant l'activité métabolique des bactéries organohétérotrophes, e.g. les bactéries sulfato-réductrices, qui sont associées aux micro-organismes phototrophes dans les biofilms La calcification peut aussi être contrôlée directement par l'interaction du calcium avec la matière organique, notamment les polymères extracellulaires sécrétés par les microorganismes (EPS) ou les fractions macromoléculaires riches en acides aspartique et glutamique de la matière organique dissoute (MOD)

    The supersymmetric configurations of N=2, d=4 supergravity coupled to vector supermultiplets

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    We classify all the supersymmetric configurations of ungauged N=2,d=4 supergravity coupled to n vector multiplets and determine under which conditions they are also classical solutions of the equations of motion. The supersymmetric configurations fall into two classes, depending on the timelike or null nature of the Killing vector constructed from Killing spinor bilinears. The timelike class configurations are essentially the ones found by Behrndt, Luest and Sabra, which exhaust this class and are the ones that include supersymmetric black holes. The null class configurations include pp-waves and cosmic strings.Comment: 44 pages, some references adde

    Synthesis of Porous Inorganic Hollow Fibers without Harmful Solvents

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    A route for the fabrication of porous inorganic hollow fibers with high surface-area-to-volume ratio that avoids harmful solvents is presented. The approach is based on bio-ionic gelation of an aqueous mixture of inorganic particles and sodium alginate during wet spinning. In a subsequent thermal treatment, the bio-organic material is removed and the inorganic particles are sintered. The method is applicable to the fabrication of various inorganic fibers, including metals and ceramics. The route completely avoids the use of organic solvents, such as N-methyl-2-pyrrolidone, and additives associated with the currently used fiber fabrication methods. In addition, it inherently avoids the manifestation of so-called macro voids and allows the facile incorporation of additional metal oxides in the inorganic hollow fibers

    935-38 Restenosis After Coronary Angioplasty is Associated with the Activation Status of Circulating Phagocytes Before Treatment

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    BackgroundThe purpose of this study was to identify biological risk factors for restenosis after PTCA, in order to predict the long-term outcome of PTCA before treatment.Methods and ResultsTo investigate whether blood granulocytes and monocytes could determine luminal renarrowing after PTCA, several characteristics of these phagocytes were assessed before angioplasty in 32 patients who underwent PTCA of one coronary artery and who had repeat angiograms at six months follow-up. The plasma levels 1L-1β, TNF-α, IL-6, fibrinogen, C-reactive protein and LP(a) before angioplasty were assessed as well. We found that the expression of the membrane antigens CD64, CD66 and CD67 by granulocytes was inversely associated with the luminal renarrowing normalized for vessel size (relative loss) at six months after PTCA. while the production of IL-1β by stimulated monocytes was positively associated with the relative loss. Next. these univariate predictors were corrected for the established clinical risk factors, dilation of the LAD, current smoking and angina class.Multiple linear regression analysis showed that luminal renarrowing could be predicted reliably (R2=0.65; P<0.0001) in this patients group on the basis of the vessel dilated and only two biological risk factors that reflect the activation status of blood phagocytes, i.e., the expression of CD66 by granulocytes and the production of IL-lβ by stimulated monocytes.ConclusionsThe results of the present study indicate that activated blood granulocytes prevent luminal renarrowing after PTCA, while activated blood monocytes promote restenosis. To validate this new finding further study in an independent patients group is required

    Late Lumen Loss After Coronary Angioplasty Is Associated With the Activation Status of Circulating Phagocytes Before Treatment

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    Background The purpose of this pilot study was to identify biological risk factors for restenosis after percutaneous transluminal coronary angioplasty (PTCA) to predict the long-term outcome of PTCA before treatment. Methods and Results To investigate whether blood granulocytes and monocytes could determine luminal renarrowing after PTCA, several characteristics of these phagocytes were assessed before angioplasty in 32 patients who underwent PTCA of one coronary artery and who had repeat angiograms at 6-month follow-up. The plasma levels of interleukin (IL)-1ß, tumor necrosis factor-, IL-6, fibrinogen, C-reactive protein, and lipoprotein(a) before angioplasty were assessed as well. We found that the expression of the membrane antigens CD64, CD66, and CD67 by granulocytes was inversely associated with the luminal renarrowing normalized for vessel size (relative loss) at 6 months after PTCA, while the production of IL-1ß by stimulated monocytes was positively associated with the relative loss. Next, these univariate predictors were corrected for the established clinical risk factors of dilation of the left anterior descending coronary artery and current smoking, which were statistically significant classic predictors in our patient group. Only the expression of CD67 did not predict late lumen loss independent of these established clinical risk factors. Multiple linear regression analysis showed that luminal renarrowing could be predicted reliably (R2=.65; P<.0001) in this patient group on the basis of the vessel dilated and only two biological risk factors that reflect the activation status of blood phagocytes, ie, the expression of CD66 by granulocytes and the production of IL-1ß by stimulated monocytes. Conclusions The results of the present study indicate that activated blood granulocytes prevent luminal renarrowing after PTCA, while activated blood monocytes promote late lumen loss. To validate this new finding, further study in an independent patient group is required

    Domain walls and instantons in N=1, d=4 supergravity

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    We study the supersymmetric sources of (multi-) domain-wall and (multi-) instanton solutions of generic N=1, d=4 supergravities, that is: the worldvolume effective actions for said supersymmetric topological defects. The domain-wall solutions naturally couple to the two 3-forms recently found as part of the N=1, d=4 tensor hierarchy (i.e. they have two charges in general) and their tension is the absolute value of the superpotential section L. The introduction of sources (we study sources with finite and vanishing thickness) is equivalent to the introduction of local coupling constants and results in dramatic changes of the solutions. Our results call for a democratic reformulation of N=1,d=4 supergravity in which coupling constants are, off-shell, scalar fields. The effective actions for the instantons are always proportional to the coordinate orthogonal to the twist-free embedding of the null-geodesic (in the Wick-rotated scalar manifold) describing the instanton. We show their supersymmetry and find the associated supersymmetric (multi-) instanton solutions.Comment: 34 pages, 4 figures, references adde
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