Aerothermodynamic Design of an Inductively Coupled Plasma Wind Tunnel

A new type of high-enthalpy continuous wind tunnel is being developed at the von Karman Institute, cofunded by ESA and the Belgian government to provide an unpolluted facility capable of testing TPS samples for future reentry missions. The facility was designed to meet specific total pressure and stagnation point heat flux conditions and a computer model has been written to allow the determination of all flow parameters. The code uses an engineering approach of quasi-one-dimensional nozzle with inviscid and adiabatic flow of high-temperature air in thermal and chemical equilibrium and includes a calculation of heat flux rates based on Fay and Riddell's formulation which, to be accurately used, needed an analytic expression for the velocity gradient for a supersonic flow impinging on the flat base of a cylinder. The model has been validated against measurements taken in Russian facilities. It predicts values of stagnation point heat fluxes with an accuracy of 15%, including all errors d..

Dictionnaire historique de la comparaison

Qu’est-ce que la comparaison ? En quoi est-elle utile au raisonnement historique, et plus généralement aux sciences humaines et sociales ? De l’histoire comparée proposée par Marc Bloch aux débats les plus récents sur l’histoire transnationale et connectée, ce dictionnaire offre un large panorama des références, des concepts, des débats, des méthodes et des outils essentiels à la mise en œuvre de la démarche comparatiste, à la fois dans l’espace et dans le temps. Ses courtes notices seront utiles à celles et ceux qu’intéresse cette approche, qu’il s’agisse de la pratiquer, de la penser ou de la critiquer, notamment en histoire moderne et contemporaine. Le classement des quatre-vingt-quatre entrées en plusieurs rubriques — » Épistémologies », « Boîte à outils », « Groupes sociaux », « Pratiques politiques », « Cultures européennes », « Lieux », « Croisements », « Temporalités » et « Collectifs » — éclaire les axes et les enjeux explorés par les auteurs ici rassemblés. Principalement historiens et historiennes, sociologues ou spécialistes de littérature, ils ont pour point commun de dialoguer avec la pensée de l’historien Christophe Charle, dont toute l’œuvre s’est efforcée de proposer une histoire sociale et culturelle comparée à l’échelle de l’Europe

Thrombectomy complications in large vessel occlusions: Incidence, predictors, and clinical impact in the ETIS registry

International audienceBACKGROUND AND PURPOSE: Procedural complications in thrombectomy for large vessel occlusions of the anterior circulation are not well described. We investigated the incidence, risk factors, and clinical implications of thrombectomy complications in daily clinical practice. METHODS: We used data from the ongoing prospective multicenter observational Endovascular Treatment in Ischemic Stroke Registry in France. The present study is a retrospective analysis of 4029 stroke patients with anterior large vessel occlusions treated with thrombectomy between January 2015 and May 2020 in 18 centers. We systematically collected procedural data, incidence of embolic complications, perforations and dissections, clinical outcome at 90 days, and hemorrhagic complications. RESULTS: Procedural complications occurred in 7.99% (95% CI, 7.17%–8.87%), and embolus to a new territory (ENT) was the most frequent (5.2%). Predictors of ENTs were terminal carotid/tandem occlusion (odds ratio [OR], 5 [95% CI, 2.03–12.31]; P<0.001) and an increased total number of passes (OR, 1.22 [95% CI, 1.05–1.41]; P=0.006). ENTs were associated to worse clinical outcomes (90-day modified Rankin Scale score, 0–2; adjusted OR, 0.4 [95% CI, 0.25–0.63]; P<0.001), increased mortality (adjusted OR, 1.74 [95% CI, 1.2–2.53]; P<0.001), and symptomatic intracerebral hemorrhage (adjusted OR, 1.87 [95% CI, 1.15–3.03]; P=0.011). Perforations occurred in 1.69% (95% CI, 1.31%–2.13%). Predictors of perforations were terminal carotid/tandem occlusions (39.7% versus 27.6%; P=0.028). 40.7% of patients died at 90 days, and the overall rate of poor outcome was 74.6% in case of perforation. Dissections occurred in 1.46% (95% CI, 1.11%–1.88%) and were more common in younger patients (median age, 64.2 versus 70.2 years; P=0.002). Dissections did not affect the clinical outcome at 90 days. Besides dissection, complications were independent of the thrombectomy technique. CONCLUSIONS: Thrombectomy complication rate is not negligible, and ENTs were the most frequent. ENTs and perforations were associated with disability and mortality, and terminal carotid/tandem occlusions were a risk factor

Successful Thrombectomy Improves Functional Outcome in Tandem Occlusions with a Large Ischemic Core

International audienceBackground: Emergent stenting in tandem occlusions and mechanical thrombectomy (MT) of acute ischemic stroke related to large vessel occlusion (LVO-AIS) with a large core are tested independently. We aim to assess the impact of reperfusion with MT in patients with LVO-AIS with a large core and a tandem occlusion and to compare the safety of reperfusion between large core with tandem and nontandem occlusions in current practice. Methods: We analyzed data of all consecutive patients included in the prospective Endovascular Treatment in Ischemic Stroke Registry in France between January 2015 and March 2023 who presented with a pretreatment ASPECTS (Alberta Stroke Program Early CT Score) of 0–5 and angiographically proven tandem occlusion. The primary end point was a favorable outcome defined by a modified Rankin Scale (mRS) score of 0–3 at 90 days. Results: Among 262 included patients with a tandem occlusion and ASPECTS 0–5, 203 patients (77.5%) had a successful reperfusion (modified Thrombolysis in Cerebral Infarction grade 2b-3). Reperfused patients had a favorable shift in the overall mRS score distribution (adjusted odds ratio [aOR], 1.57 [1.22–2.03]; P < 0.001), higher rates of mRS score 0–3 (aOR, 7.03 [2.60–19.01]; P < 0.001) and mRS score 0–2 at 90 days (aOR, 3.85 [1.39–10.68]; P = 0.009) compared with nonreperfused. There was a trend between the occurrence of successful reperfusion and a decreased rate of symptomatic intracranial hemorrhage (aOR, 0.5 [0.22–1.13]; P = 0.096). Similar safety outcomes were observed after large core reperfusion in tandem and nontandem occlusions. Conclusions: Successful reperfusion was associated with a higher rate of favorable outcome in large core LVO-AIS with a tandem occlusion, with a safety profile similar to nontandem occlusion