996 resultados para 160-968


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von H. Graetz

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von H. Graetz

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The production rate of right-handed neutrinos from a Standard Model plasma at a temperature above a hundred GeV has previously been evaluated up to NLO in Standard Model couplings (g ~ 2/3) in relativistic (M ~ πT) and non-relativistic regimes (M ≫ πT), and up to LO in an ultrarelativistic regime (M ≲ gT). The last result necessitates an all-orders resummation of the loop expansion, accounting for multiple soft scatterings of the nearly light-like particles participating in 1↔2 reactions. In this paper we suggest how the regimes can be interpolated into a result applicable for any right-handed neutrino mass and at all temperatures above 160GeV. The results can also be used for determining the lepton number washout rate in models containing right-handed neutrinos. Numerical results are given in a tabulated form permitting for their incorporation into leptogenesis codes. We note that due to effects from soft Higgs bosons there is a narrow intermediate regime around M ~g 1/2 T in which our interpolation is phenomenological and a more precise study would be welcome.

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Vorbesitzer: Eljāqīm Carmoly; Abraham Merzbacher

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The immunomodulatory drug FTY720 is presently approved for the treatment of relapsing-remitting multiple sclerosis. It is a prodrug that requires activation by sphingosine kinase 2 (SK-2) to induce T cell homing to secondary lymphoid tissue. In this study, we have investigated the role of SK-2 in experimental autoimmune encephalomyelitis (EAE) in C57BL/6 mice. We show that SK-2 deficiency reduced clinical symptoms of EAE. Furthermore, in SK-2-deficient mice, the protective effect of FTY720 on EAE was abolished, while the non-prodrug FTY720-derivative ST-968 was still fully active. Protection was paralleled by reduced numbers of T-lymphocytes in blood and a reduced blood-brain-barrier leakage. This correlated with reduced mRNA expression of ICAM-1, VCAM-1, but enhanced expression of PECAM-1. A similar regulation of permeability and of PECAM-1 was seen in primary cultures of isolated mouse brain vascular endothelial cells and in a human immortalized cell line upon SK-2 knockdown. In summary, these data demonstrated that deletion of SK-2 exerts a protective effect on the pathogenesis of EAE in C57BL/6 mice and that SK-2 is essential for the protective effect of FTY720 but not of ST-968. Thus, ST-968 is a promising novel immunomodulatory compound that may be a valuable alternative to FTY720 under conditions where SK-2 activity is limited.

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Vorbesitzer: Bartholomaeusstift Frankfurt am Main

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u.a.: Umzug aus gesundheitlichen Gründen nach Naumburg oder Erfurt; Einschreiten der Polizei in Frankfurt am Main; Eisenbahn Thüringen; Höhe der Miete in Berlin, Beschreibung Berliner Wohnung; Wielandt; Geheimer Hofrat Carl John;

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Vorbesitzer: Dominikanerkloster Frankfurt am Main

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Deutsche Latern: Abrechnung