44 research outputs found
K-edge X-ray absorption spectra in transition metal oxides beyond the single particle approximation: shake-up many body effects
The near edge structure (XANES) in K-edge X-ray absorption spectroscopy (XAS)
is a widely used tool for studying electronic and local structure in materials.
The precise interpretation of these spectra with the help of calculations is
hence of prime importance, especially for the study of correlated materials
which have a complicated electronic structure per se. The single particle
approach, for example, has generally limited itself to the dominant dipolar
cross-section. It has long been known however that effects beyond this approach
should be taken into account, both due to the inadequacy of such calculations
when compared to experiment and the presence of shake-up many-body satellites
in core-level photoemission spectra of correlated materials. This effect should
manifest itself in XANES spectra and the question is firstly how to account for
it theoretically and secondly how to verify it experimentally. By using
state-of-the-art first principles electronic structure calculations and 1s
photoemission measurements we demonstrate that shake-up many-body effects are
present in K-edge XAS dipolar spectra of NiO, CoO and CuO at all energy scales.
We show that shake-up effects can be included in K-edge XAS spectra in a simple
way by convoluting the single-particle first-principles calculations including
core-hole effects with the 1s photoemission spectra. We thus describe all
features appearing in the XAS dipolar cross-section of NiO and CoO and obtain a
dramatic improvement with respect to the single-particle calculation in CuO.
These materials being prototype correlated magnetic oxides, our work points to
the presence of shake-up effects in K-edge XANES of most correlated transition
metal compounds and shows how to account for them, paving the way to a precise
understanding of their electronic structure.Comment: 6 pages, 4 picture
A consistent methodology for the derivation and calibration of a macroscopic turbulence model for flows in porous media
This work aims to model turbulent flows in media laden with solid structures according to porous media approach. A complete set of macroscopic transport equations is derived by spatially averaging the Reynolds averaged governing equations. A two-scale analysis highlights energy transfers between macroscopic and sub-filter kinetic energies (dispersive and turbulent kinetic energies). Additional terms coming from the averaging procedure and representing solids/fluid interactions and turbulent contributions are modeled. Connections between turbulence modeling and dispersion modeling are presented. Other closure expressions are determined using physical considerations and spatial averaging of microscopic computations. A special care is given to the calibration methodology for the phenomenological coefficients. Results of the present model are successfully compared to volume-averaged reference results coming from fine scale computations and show significant improvements with respect to previous macroscopic models
CC9 Livestock-Associated Staphylococcus aureus Emerges in Bloodstream Infections in French Patients Unconnected With Animal Farming
We report 4 bloodstream infections associated with CC9 agr type II Staphylococcus aureus in individuals without animal exposure. We demonstrate, by microarray analysis, the presence of egc cluster, fnbA, cap operon, lukS, set2, set12, splE, splD, sak, epiD, and can, genomic features associated with a high virulence potential in human
A recessive form of hyper-IgE syndrome by disruption of ZNF341-dependent STAT3 transcription and activity.
Heterozygosity for human () dominant-negative (DN) mutations underlies an autosomal dominant form of hyper-immunoglobulin E syndrome (HIES). We describe patients with an autosomal recessive form of HIES due to loss-of-function mutations of a previously uncharacterized gene, ZNF341 is a transcription factor that resides in the nucleus, where it binds a specific DNA motif present in various genes, including the promoter. The patients\u27 cells have low basal levels of STAT3 mRNA and protein. The autoinduction of STAT3 production, activation, and function by STAT3-activating cytokines is strongly impaired. Like patients with DN mutations, ZNF341-deficient patients lack T helper 17 (T17) cells, have an excess of T2 cells, and have low memory B cells due to the tight dependence of STAT3 activity on ZNF341 in lymphocytes. Their milder extra-hematopoietic manifestations and stronger inflammatory responses reflect the lower ZNF341 dependence of STAT3 activity in other cell types. Human ZNF341 is essential for the transcription-dependent autoinduction and sustained activity of STAT3
Coccidioïdomycose : une maladie d’importation d’actualité en France
International audienceCoccidioidomycosis is an endemic mycosis in the southwest of United States resulting from the inhalation of arthrospores present in desert soil. The authors present a case of uncomplicated pulmonary coccidioidomycosis in a healthy woman, acquired during a recent trip to California. The initial clinical presentation first suggested a diagnosis of community-acquired pneumonia, then of tuberculosis. The diagnosis was finally reached with blood tests and mycological culture of broncho-alveolar lavage fluid. The final identification of Coccidioides immitis was made by molecular analysis. Clinical resolution of the infection was obtained after three months of posaconazole treatment. Coccidioidomycosis is a major cause of pneumonia. Its diagnosis requires specific investigation such as mycological culture, histology, blood tests and molecular biology helps to identify the species. The progression of the disease as well as the associated immunocellular deficit are strictly correlated with the onset of complications and late relapses despite an adequate initial treatment using antifungal molecules and/or surgery.La coccidioïdomycose est une mycose endémique résultant de l’inhalation d’arthrospores présentes dans les sols désertiques. Nous rapportons un cas de coccidioïdomycose pulmonaire non compliquée, chez une femme non immunodéprimée après un voyage en Californie. La présentation clinique initiale avait conduit à un diagnostic de pneumopathie communautaire, puis de tuberculose. Le diagnostic a été corrigé grâce à la sérologie et la culture du lavage bronchoalvéolaire, complétée par l’identification moléculaire de Coccidioides immitis. L’évolution était favorable après trois mois de traitement par posaconazole. La coccidioïdomycose est surtout responsable de pneumonies isolées. Le diagnostic nécessite une recherche spécifique et bénéficie de la biologie moléculaire pour l’identification d’espèce. Les facteurs associés, essentiellement immunitaires, expliquent la gravité de l’infection et la survenue de complications et rechutes à distance même en cas de traitement bien conduit. Celui-ci repose sur les antifongiques azolés ou polyéniques, plusieurs mois, voire à vie en cas d’atteinte neurologique et/ou déficit immunitaire