The effective gravitational decoupling between dark matter and the CMB

We present a detailed and self-contained analytical derivation of the evolution of sub-horizon cosmological perturbations before decoupling, based on previous work by S. Weinberg. These solutions are valid in the minimal LCDM scenario, to first order in perturbation theory, in the tight-coupling limit and neglecting neutrino shear stress. We compare them to exact numerical solutions computed by a Boltzmann code, and we find the two to be in very good agreement. The analytic solutions show explicitly that CDM and the baryon-photon fluid effectively behave as separate self-gravitating fluids until the epoch of baryon drag. This in turn leads to the surprising conclusion that the CMB is much less sensitive to the clustering properties of minimally coupled Dark Matter models than what would be naively expected.Comment: 23 pages, 8 figures, 2 references added, few sentences clarifie

Frequency of Abnormally Low Neuropsychological Scores in Post-COVID-19 Syndrome: the Geneva COVID-COG Cohort

Objective: Several studies have reported poor long-term neuropsychological performances in patients following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but none has yet considered the effect of administering multiple intercorrelated neuropsychological tests and assessed the frequency of cognitive deficits in a normative population. Our aim was therefore to assess the presence of cumulative neuropsychological deficits in an actual post-coronavirus disease of 2019 (COVID-19) comparison group versus one simulated using Monte-Carlo methods. Method: Validated neuropsychological Monte-Carlo simulation methods were applied to scores from a battery of neuropsychological tests (memory, executive, attentional, perceptual, logical reasoning, language, and ideomotor praxis) administered to 121 patients who had had mild, moderate, or severe COVID-19 (mean age: 56.70 years; 32% women), 222 ± 43 days post-infection. The cumulative percentages of the three severity subgroups were compared with the results of a false discovery rate-corrected probability analysis based on normative data. Results: The cumulative percentages of deficits in memory and executive functions among the severe and moderate patients were significantly higher than those estimated for the normative population. Moderate patients also had significantly more deficits in perception and logical reasoning. In contrast, the mild group did not have significantly more cumulative deficits. Conclusions: Moderate and severe forms of COVID-19 cause greater long-term neuropsychological deficits than those that would be found in a normative population, reinforcing the hypothesis of long-term effects of SARS-CoV-2 on cognitive function, independent of the severity of the initial infection.</p

Réponse des têtes de bassin aux fluctuations environnementales, du Tardiglaciaire à l’Actuel : l’exemple du bassin supérieur de la Loire dans le massif du Mézenc (Velay-Vivarais, Sud-Est du Massif central, France).

International audienceDans le Massif central, les têtes de bassin (ordre Strahler 3-4 et inférieur) sont un domaine encore peu investi pour l’étude des flux hydro-sédimentaires liés aux fluctuations environnementales quaternaires. Le système hydrographique naissant recèle pourtant d’intéressantes archives sédimentaires, à l’échelle au moins des temps postérieurs au dernier glaciaire. Motivé par les observations préliminaires effectuées ces dernières années dans le massif du Mézenc (Velay oriental, bassin supérieur de la Loire), le programme WRACC, financé par l’Etablissement Public Loire et le FEDER, se propose d’aborder l’étude de ces dépôts et de leur environnement sous l’angle d’une approche géoarchéologique pluridisciplinaire. La prospection est en cours, et s’appuie sur des coupes naturelles ainsi que sur l’ouverture de tranchées en travers d’un fond de vallon (Champetienne) où se sont concentrées nos investigations. Les données analytiques ne sont pas encore disponibles. Il est cependant possible, grâce aux observations stratigraphiques et aux premières datations obtenues, de poser quelques jalons. A l’échelle de l’Holocène au moins, les cours d’eau semblent avoir fluctué dans leur fond de vallon sans progrès de l’encaissement, alternant phases de stockage et de déstockage. La forme des chenaux successifs et le gabarit des matériaux les remblayant témoignent des fluctuations corrélatives du style fluvial et de la compétence. Les séquences débutent généralement par une nappe alluviale très grossière d’âge indéterminé témoignant d’un système de forte énergie. Le 4e-5e siècle après J.-C. semble marquer le terme d’une phase de stabilité avec remaniement des horizons pédologiques et de la végétation. Après cette vigoureuse phase de détritisme, la période stable allant des 8e-9e siècles au 15e siècle est enfin suivie par une crise érosive de faible énergie à l’Epoque Moderne, où la part respective des forçages naturels (PAG) et anthropiques peut être plus particulièrement discutée

Development and manufacturing of SPO X-ray mirrors

The Silicon Pore Optics (SPO) technology has been established as a new type of X-ray optics enabling future X-ray observatories such as ATHENA. SPO is being developed at cosine together with the European Space Agency (ESA) and academic as well as industrial partners. The SPO modules are lightweight, yet stiff, high-resolution X-ray optics, allowing missions to reach a large effective area of several square meters. These properties of the optics are mainly linked to the mirror plates consisting of mono-crystalline silicon. Silicon is rigid, has a relatively low density, a very good thermal conductivity and excellent surface finish, both in terms of figure and surface roughness. For Athena, a large number of mirror plates is required, around 100,000 for the nominal configuration. With the technology spin-in from the semiconductor industry, mass production processes can be employed to manufacture rectangular shapes SPO mirror plates in high quality, large quantity and at low cost. Within the last years, several aspects of the SPO mirror plate have been reviewed and undergone further developments in terms of effective area, intrinsic behavior of the mirror plates and mass production capability. In view of flight model production, a second source of mirror plates has been added in addition to the first plate supplier. The paper will provide an overview of most recent plate design, metrology and production developments

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine