Sur les écoulements de disque tournant

Les écoulements de disque(s) tournant(s) trouvent des applications dans des domaines très variés comme l'astrophysique, la géophysique et surtout les turbomachines. Une majeure partie de cette étude concerne d'ailleurs les écoulements turbulents de type rotor-stator soumis à un flux axial, écoulements que l'on retrouve dans la turbopompe à hydrogène liquide du moteur Vulcain d'Ariane V. D'un point de vue fondamental, ils offrent une géométrie simple ou la rotation influence la structure de la turbulence. Cet article présente une revue sur les écoulements confinés entre un disque tournant et un disque fixe avec ou sans flux imposé pour une gamme de rapport d'aspect couvrant les écoulements de type Batchelor à couches limites séparées et les écoulements de type Couette de torsion à couches limites jointes. Ces écoulements ont été abordés sous différents aspects: stabilité, transition vers la turbulence et écoulements pleinement turbulents, que ce soit expérimentalement ou par simulation numérique. Des résultats concernant des écoulements turbulents avec transferts de chaleur, plus proches des écoulements industriels, sont également présentés

Expansion of Regulatory T Cells in Patients with Langerhans Cell Histiocytosis

Frederic Geissmann and colleagues find that Langerhans cell accumulation in Langerhans cell histiocytosis results from survival rather than uncontrolled proliferation, and is associated with the expansion of regulatory T cells

The Genome Sequence of the Grape Phylloxera Provides Insights into the Evolution, Adaptation, and Invasion Routes of an Iconic Pest

Background: Although native to North America, the invasion of the aphid-like grape phylloxera Daktulosphaira vitifoliae across the globe altered the course of grape cultivation. For the past 150 years, viticulture relied on grafting-resistant North American Vitis species as rootstocks, thereby limiting genetic stocks tolerant to other stressors such as pathogens and climate change. Limited understanding of the insect genetics resulted in successive outbreaks across the globe when rootstocks failed. Here we report the 294-Mb genome of D. vitifoliae as a basic tool to understand host plant manipulation, nutritional endosymbiosis, and enhance global viticulture. Results: Using a combination of genome, RNA, and population resequencing, we found grape phylloxera showed high duplication rates since its common ancestor with aphids, but similarity in most metabolic genes, despite lacking obligate nutritional symbioses and feeding from parenchyma. Similarly, no enrichment occurred in development genes in relation to viviparity. However, phylloxera evolved > 2700 unique genes that resemble putative effectors and are active during feeding. Population sequencing revealed the global invasion began from the upper Mississippi River in North America, spread to Europe and from there to the rest of the world. Conclusions: The grape phylloxera genome reveals genetic architecture relative to the evolution of nutritional endosymbiosis, viviparity, and herbivory. The extraordinary expansion in effector genes also suggests novel adaptations to plant feeding and how insects induce complex plant phenotypes, for instance galls. Finally, our understanding of the origin of this invasive species and its genome provide genetics resources to alleviate rootstock bottlenecks restricting the advancement of viticulture

Information quality and information search in judgment tasks : a laboratory study

M.S.Terrence Connoll

Mise en place d'un module d'apprentissage de la consultation en gynécologie-obstétrique sur un campus virtuel (à l'initiative du campus de gynécologie-obstétrique par un logiciel de simulation (VIPS))

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

Simulation numérique directe des écoulements rotor-stator en cavité annulaire

On revisite par DNS et visualisations les instabilités qui apparaissent le long du disque fixe dans une cavité rotor-stator annulaire. La première instabilité (type II) est convective et apparaît sous la forme de rouleaux concentriques qui se déplacent vers le centre de la cavité. La seconde de type I apparaît sous la forme de spirales positives à travers une bifurcation de Hopf supercritique. Un bon accord entre les deux approches est obtenu sur les caractéristiques de ces instabilités

Revisiting the two first instabilities of the flow in an annular rotor-stator cavity

International audienc

The Association Between Age and Admission to an Inappropriate Ward: A Cross-Sectional Survey in France

Half of elderly patient hospitalizations are preceded by an emergency department (ED) visit. Hospitalization in inappropriate wards (IWs), which is more frequent in case of ED overcrowding and high hospital occupancy, leads to increased morbidity. Elderly individuals are the most exposed to these negative health care outcomes. Based on a nationwide cross-sectional survey involving all EDs in France, the aim of this study was to explore whether age was associated with admission to an IW after visiting an ED. Among the 4384 patients admitted in a medical ward, 4065 were admitted in the same hospital where the ED was located, among which 17.7% were admitted to an IW. Older age was associated with an increased likelihood of being admitted to an IW (OR = 1.39; 95% CI = 1.02-1.90 for patients aged 85 years and older and OR = 1.40; 95% CI = 1.02-1.91 for patients aged 75-84 years, compared with those under 45 years). ED visits during peak periods and cardio-pulmonary presenting complaint were also associated with an increased likelihood of admission to an IW. Despite their higher vulnerability, elderly patients are more likely to be admitted to an IW than younger patients. This result reinforces the need for special attention to be given to the hospitalization of this fragile population

Neutrophil extracellular traps exert both pro- and anti-inflammatory actions in rheumatoid arthritis that are modulated by C1q and LL-37

International audienceObjective: Neutrophil extracellular traps (NET), produced by activated polymorphonuclear neutrophils (PMN), are supposed to play a role in the pathogenesis of rheumatoid arthritis (RA), a chronic inflammatory autoimmune disease characterized by anti-citrullinated protein antibodies (ACPA). Indeed, NET contain citrullinated autoantigens and some RA autoantibodies recognize NET. However, the mechanisms by which NET trigger or perpetuate the inflammatory process in RA are hitherto not elucidated. We hypothesized that, in addition to citrullination, NET might also contain stimulatory proteins and directly activate inflammatory target cells, as PMN and macrophages. Methods: NET antigenic and inflammatory properties were analyzed in 157 healthy donors (HD) and RA patients, the largest analysis reported so far. Primary PMN and monocyte-derived macrophages were isolated and immunoglobulin G (IgG) purified. NET were induced (NETosis), isolated and quantified. NET antigenicity was analyzed by fluorescence microscopy. PMN and macrophages were stimulated with NET with/without ACPA, C1q, LL-37 or lipopolysaccharide (LPS) and cell activation was estimated by flow cytometry and ELISA. Results: PMN from RA patients produced more NET than HD PMN. We next dissected how NET mechanistically affect inflammatory cells. Particularly, we show for the first time that RA and HD NET activated both resting macrophages and PMN, but importantly RA NET were more stimulatory, leading to secretion of inflammatory cytokines and up-regulation of HLA/CD86/CD11b. IgG from ACPA-positive RA patients specifically recognized RA and even HD NET. Nevertheless, NET-induced cell activation occurs independently of immune complex formation with ACPA. Likewise, endosomal acidification was not required. Notably, we also report that complement C1q increased the NET stimulatory activity on macrophages only, due to higher expression of C1q receptors, which was further supported by the LL-37 antimicrobial peptide. In contrast, NET specifically inhibited interleukin (IL)-6 secretion by LPS-activated macrophages and not PMN, especially with C1q/LL-37. This inhibition was not mediated by NET-derived proteases or LPS neutralization and was associated with the simultaneous induction of IL-10 secretion. Conclusion: We show that NET possess both pro- and anti-inflammatory properties depending on target cells, their activation levels and C1q/LL-37. Thus, independently of ACPA, NET modulate RA chronic inflammation via this new dual activity we identified. In addition, NET may trigger autoimmunity in RA as ACPA recognize NET antigens but not non-activated PMN. Therefore, we conclude that excess of NETosis together with enhanced NET activity participate to RA pathogenesis at different levels