THEMIS as particle detector: Spectropolarimetry of solar flares

The progressive phases of three solar flares have beenobserv ed with THEMIS in July 2000, using the multiline spectropolarimetric MTR mode. A preliminary analysis of the characteristics of the polarization of the Hα and Hβ lines observed at the beginning of the progressive phase of one of these flares is presented

Sleeping arrangements and mass distribution of bed nets in six districts in central and northern Mozambique

OBJECTIVE: Universal coverage with insecticide-treated bed nets is a cornerstone of modern malaria control. Mozambique has developed a novel bed net allocation strategy, where the number of bed nets allocated per household is calculated on the basis of household composition and assumptions about who sleeps with whom. We set out to evaluate the performance of the novel allocation strategy. METHODS: 1,994 households were visited during household surveys following two universal coverage bed net distribution campaigns in Sofala and Nampula Provinces in 2010-2013. Each sleeping space was observed for the presence of a bed net, and the sleeping patterns for each household were recorded. The observed coverage and efficiency were compared to a simulated coverage and efficiency had conventional allocation strategies been used. A composite indicator, the product of coverage and efficiency, was calculated. Observed sleeping patterns were compared with the sleeping pattern assumptions. RESULTS: In households reached by the campaign, 93% (95% CI: 93-94%) of sleeping spaces in Sofala and 84% (82-86%) in Nampula were covered by campaign bed nets. The achieved efficiency was high, with 92% (91-93%) of distributed bed nets in Sofala and 93% (91-95%) in Nampula covering a sleeping space. Using the composite indicator, the novel allocation strategy outperformed all conventional strategies in Sofala and was tied for best in Nampula. The sleeping pattern assumptions were completely satisfied in 66% of households in Sofala and 56% of households in Nampula. The most common violation of the sleeping pattern assumptions was that male children 3-10 years of age tended not to share sleeping spaces with female children 3-10 or 10-16 years of age. CONCLUSIONS: The sleeping pattern assumptions underlying the novel bed net allocation strategy are generally valid, and net allocation using these assumptions can achieve high coverage and compare favorably with conventional allocation strategies. This article is protected by copyright. All rights reserved

Evaluation of Convalescent Plasma for Ebola Virus Disease in Guinea

: In the wake of the recent outbreak of Ebola virus disease (EVD) in several African countries, the World Health Organization prioritized the evaluation of treatment with convalescent plasma derived from patients who have recovered from the disease. We evaluated the safety and efficacy of convalescent plasma for the treatment of EVD in Guinea. : In this nonrandomized, comparative study, 99 patients of various ages (including pregnant women) with confirmed EVD received two consecutive transfusions of 200 to 250 ml of ABO-compatible convalescent plasma, with each unit of plasma obtained from a separate convalescent donor. The transfusions were initiated on the day of diagnosis or up to 2 days later. The level of neutralizing antibodies against Ebola virus in the plasma was unknown at the time of administration. The control group was 418 patients who had been treated at the same center during the previous 5 months. The primary outcome was the risk of death during the period from 3 to 16 days after diagnosis with adjustments for age and the baseline cycle-threshold value on polymerase-chain-reaction assay; patients who had died before day 3 were excluded. The clinically important difference was defined as an absolute reduction in mortality of 20 percentage points in the convalescent-plasma group as compared with the control group. : A total of 84 patients who were treated with plasma were included in the primary analysis. At baseline, the convalescent-plasma group had slightly higher cycle-threshold values and a shorter duration of symptoms than did the control group, along with a higher frequency of eye redness and difficulty in swallowing. From day 3 to day 16 after diagnosis, the risk of death was 31% in the convalescent-plasma group and 38% in the control group (risk difference, -7 percentage points; 95% confidence interval [CI], -18 to 4). The difference was reduced after adjustment for age and cycle-threshold value (adjusted risk difference, -3 percentage points; 95% CI, -13 to 8). No serious adverse reactions associated with the use of convalescent plasma were observed. : The transfusion of up to 500 ml of convalescent plasma with unknown levels of neutralizing antibodies in 84 patients with confirmed EVD was not associated with a significant improvement in survival. (Funded by the European Union's Horizon 2020 Research and Innovation Program and others; ClinicalTrials.gov number, NCT02342171.).<br/

Stacking sequence optimization of composite tubes submitted to crushing using the discrete ply model

International audienceThe purpose of this study is to study the applicability of Discrete Ply Modeling (DPM) to crushing of composite tubes and to study the effect of stacking sequence and trigger geometry on the Specific Energy Absorption (SEA). The model was first validated with experimental results after which various stacking sequences were simulated to optimize it with an aim to increase the SEA.The stacking sequence [90/02/90/03/90/0/90] performed the best in terms of SEA value. As a result, the confidence of the DPM has been proven for some draping sequences but seems to be less confident to simulate the trigger effect

Energy dissipation during tubular structures crash for aircraft seats development

International audienceDu fait de leur légèreté et propriétés mécaniques intéressantes, l’utilisation des matériaux composites dans le domaine aéronautique est de plus en plus fréquente, même pour la réalisation de parties structurales, principalement conçues à partir d’ensembles métalliques jusqu’à présent. Allant en ce sens, l’objet de cette étude est la réalisation et la validation d’une structure de siège aéronautique en composite résistant au cas d’un crash d’avion

Crash de structures composites tubulaires et absorption d’énergie pour le développement de sièges aéronautiques

National audienceDans l’optique de la conception et du développement d’un siège aéronautique et afin de respecter la règlementation sécuritaire en vigueur, la structure du siège développé doit permettre une dissipation rapide de l’énergie perçue en cas de crash aérien (Fig. 1) dans le but de protéger les passagers. La majorité des systèmes passés et actuels intégrés à la structure du siège et permettant la dissipation d’énergie (Fig. 2) est constituée de composants métalliques. Lors d’une sollicitation en cas de crash, la déformation plastique de ces pièces métalliques permet la dissipation d’énergie. Actuellement, l’industrie et la recherche se tournent vers la piste des matériaux composites pour substituer de tels systèmes. Le choix d’une structure en matériaux composites a été conduit du fait de la légèreté de ce type de matériaux, de leurs propriétés mécaniques intéressantes et du contexte aéronautique. Cependant le comportement de ces matériaux lors de sollicitations mécaniques importantes est fortement différent des matériaux métalliques, notamment dû au fait que les procédés d’endommagement sont très distincts. Le but de cette étude portant sur des structures tubulaires composites est d’évaluer leur capacité à dissiper l’énergie engendrée en cas de crash. A cette fin, différentes structures tubulaires en composites de composition différentes ont été testées en compression (Fig. 3 et 4) dans le but de déterminer leur comportement, comparer leur propriétés et enfin calculer leur valeur de SEA (absorption d'énergie spécifique, en kJ.kg-1) servant à évaluer leur capacité à dissiper de l’énergie. Ces dernières sont indirectement issues des courbes effort-déplacement obtenues lors des essais d’écrasement (Fig. 5). On peut également souligner que les différents essais de compression ont été instrumentés et suivis au moyen de caméras thermiques (Fig. 4 et 6), dans le but de comparer et de tenter de retrouver la valeur de l’énergie dissipée sous forme thermique lors de l’endommagement. Les différents résultats de comportement en compression sont également utilisés dans le but de construire et enrichir un modèle de calcul par éléments finis (Fig. 7 et 8) permettant de simuler la réponse de structures composites de différentes natures soumises au crash en intégrant la géométrie et la composition de la structure (Fig. 8). L’objectif du travail de recherche présenté est ainsi d’évaluer l’énergie pouvant être dissipée par des structures tubulaires composites, de comparer les absorptions induites par des structures composites de compositions différentes et/ou bi-matériaux et enfin de fournir un modèle éléments finis représentant le comportement de structures composites en compression jusqu’à l’endommagement et la ruine de la structure

Energy dissipation during tubular structures crash for aircraft seats development

International audienceDu fait de leur légèreté et propriétés mécaniques intéressantes, l’utilisation des matériaux composites dans le domaine aéronautique est de plus en plus fréquente, même pour la réalisation de parties structurales, principalement conçues à partir d’ensembles métalliques jusqu’à présent. Allant en ce sens, l’objet de cette étude est la réalisation et la validation d’une structure de siège aéronautique en composite résistant au cas d’un crash d’avion