4,659 research outputs found

    Acute experimental glomerulonephritis induced by the glomerular deposition of circulating polymerid IgA-Concanavalin A complexes

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    The perfusion of polymeric or secretory IgA-Concanavalin A complexes into the aorta of rats led to a mannose-dependent binding of both IgA and lectin to the glomerular capillary wall, as shown by double immunolocalization experiments, by quantitative analysis of the amount of radiolabeled complexes bound per g of kidney, and by blocking experiments with the corresponding carbohydrate. Rats injected with amounts of those complexes as low as 500 ?g developed, one hour later, a focal and segmental proliferative glomerulonephritis characterized by the deposition of injected complexes and of rat C3 and rat fibrin/ fibrinogen in most glomeruli ; focal thrombosis and small areas of necrosis in 10 to 15% of glomeruli, confined to the periphery of a single lobule of the tuft and segmental infiltration of these glomeruli by polymorphonuclear leucocytes and platelets. At the same time, many mesangial cells exhibited a hyperactive appearance, and red blood cells were noted in tubular lumens. In contrast, rats similarly injected with either monomeric IgA-ConA complexes, multimeric or secretory IgA-peanut agglutinin complexes or polymeric or monomeric IgA aggregates of comparable apparent molecular weight did not develop obvious glomerular lesions within one hour. The data indicate that preformed polymeric IgA-ConA complexes can specifically bind to glomerular structures in vivo and trigger acute glomerular lesions locally, analogous to those observed in some glomerular diseases associated with a cryoglobulinemia

    Les système MF-InF3 (M = Rb, Cs, Tl)

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    International audienceL'étude des systèmes MF-InF3 (M = Rb, Cs, Tl) met en évidence dans tous les cas des composés de formules M3InF6, MInF4 et MIn3F10..

    Atomic motion in tilted optical lattices

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    This paper presents a formalism describing the dynamics of a quantum particle in a one-dimensional, time-dependent, tilted lattice. The formalism uses the Wannier-Stark states, which are localized in each site of the lattice, and provides a simple framework allowing fully-analytical developments. Analytic solutions describing the particle motion are explicit derived, and the resulting dynamics is studied.Comment: 6 pages, 2 figs, submitted to EPJD, Springer Verlag styl

    The Carbon-Rich Gas in the Beta Pictoris Circumstellar Disk

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    The edge-on disk surrounding the nearby young star Beta Pictoris is the archetype of the "debris disks", which are composed of dust and gas produced by collisions and evaporation of planetesimals, analogues of Solar System comets and asteroids. These disks provide a window on the formation and early evolution of terrestrial planets. Previous observations of Beta Pic concluded that the disk gas has roughly solar abundances of elements [1], but this poses a problem because such gas should be rapidly blown away from the star, contrary to observations of a stable gas disk in Keplerian rotation [1, 2]. Here we report the detection of singly and doubly ionized carbon (CII, CIII) and neutral atomic oxygen (OI) gas in the Beta Pic disk; measurement of these abundant volatile species permits a much more complete gas inventory. Carbon is extremely overabundant relative to every other measured element. This appears to solve the problem of the stable gas disk, since the carbon overabundance should keep the gas disk in Keplerian rotation [3]. New questions arise, however, since the overabundance may indicate the gas is produced from material more carbon-rich than the expected Solar System analogues.Comment: Accepted for publication in Nature. PDF document, 12 pages. Supplementary information may be found at http://www.dtm.ciw.edu/akir/Documents/roberge_supp.pdf *** Version 2 : Removed extraneous publication information, per instructions from the Nature editor. No other changes mad

    Turbidity diagrams of polyanion/polycation complexes in solution as a potential tool to predict the occurrence of polyelectrolyte multilayer deposition.

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    Surface functionalization with polyelectrolyte multilayer films (PEM films) has become very popular owing to its simplicity and versatility. However, even if some research is already available, this field of surface chemistry lacks a systematic knowledge of how the polyelectrolyte structure and solution conditions influence the growth of PEM films. In this investigation, we focus on the possible relationship between turbidity of polycation and polyanion mixtures in solution, and the buildup of PEM films made from the same polyelectrolytes in the same physicochemical conditions, namely pH, temperature and ionic strength. It comes out that for six different polycation/polyanion combinations there is a clear correlation between the turbidity evolution of polycation/polyanion complexes with the salt concentration and the evolution of the film deposition with the same parameter. In this investigation, the complexes in solution were prepared in conditions where the ratio between the number of cationic to anionic groups was close to unity. Even if there is a correlation between turbidity in solution and PEM film deposition, we found some exceptions in the low salt concentration regime. This work is an extension of the preliminary works of Cohen Stuart (D. Kovačević et al. Langmuir 18 (2002) 5607-5612) and Sukishvili et al. (S.A. Sukhishvili, E. Kharlampieva and V. Izumrudov, Macromolecules 39 (2006) 8873-8881).journal articleresearch support, non-u.s. gov't2010 Jun 012010 02 21importe

    Eigenvalue estimates for non-selfadjoint Dirac operators on the real line

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    We show that the non-embedded eigenvalues of the Dirac operator on the real line with non-Hermitian potential VV lie in the disjoint union of two disks in the right and left half plane, respectively, provided that the L1normL^1-norm of VV is bounded from above by the speed of light times the reduced Planck constant. An analogous result for the Schr\"odinger operator, originally proved by Abramov, Aslanyan and Davies, emerges in the nonrelativistic limit. For massless Dirac operators, the condition on VV implies the absence of nonreal eigenvalues. Our results are further generalized to potentials with slower decay at infinity. As an application, we determine bounds on resonances and embedded eigenvalues of Dirac operators with Hermitian dilation-analytic potentials
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