Local approach to fracture based prediction of the ΔT56J and ΔTKIc 100 shifts due to irradiation for an A508 pressure vessel steel

International audienceNuclear pressure vessel steels are subjected to irradiation embrittlement which is monitored using Charpy tests. Reference index temperatures, such as the temperature for which the mean Charpy rupture energy is equal to 56 J (T56J), are used as embrittlement indicators. The safety integrity evaluation is performed assuming that the shift of the nil-ductility reference temperature RTNDT due to irradiation is equal to the shift of T56J. A material model integrating a description of viscoplasticity, ductile damage and cleavage brittle fracture is used to simulate both the Charpy test and the fracture toughness test (CT geometry). The model is calibrated on the Charpy data obtained on an unirradiated A508 Cl.3 steel. It is then applied to irradiated materials assuming that irradiation affects solely hardening. Comparison with Charpy energy data for different amounts of irradiation shows that irradiation possibly also affects brittle fracture. The model is then applied to predict the fracture toughness shifts (ΔTKIc,100) for different levels of irradiation

Local approach to fracture based prediction of the ∆T56J and ∆T K1C100 shifts due to irradiation for an A508 pressure vessel steel

International audienceA material model integrating a description of viscoplasticity, ductile damage and brittle fracture is used to simulate both the impact (Charpy) test and the toughness (CT) fracture test. The model is calibrated on the Charpy data obtained on an unirradiated A508 Cl.3 steel. It is then applied to irradiated material assuming that irradiation affects solely hardening. Comparison with Charpy energy data for different amounts of irradiation shows that irradiation probably also affects brittle fracture. The model is then used to predict the DTKIc100 shifts for different levels of irradiation

Transferability of cleavage fracture parameters between notched and cracked geometries

International audienceThe present study investigates the temperature ...

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

Coup d'arrêt aux violences conjugales ou coup d'épée dans l'eau ?

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Le mineur de 13 ans au seuil de la responsabilité pénale

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Clarification de l'élément moral de l'infraction d'appels téléphoniques malveillants : le rendez-vous manqué de la chambre criminelle

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Réflexion sur les seuils d'âge en droit pénal de fond

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Bacteria Associated with the Parasitic Nematode Haemonchus contortus and Its Control Using Antibiotics

Internal parasitism, a significant cause of production losses in sheep, is routinely controlled by anthelmintic drenches. A better understanding and alternative control strategies are needed to combat the increasing resistance. This study investigated the presence of resident bacteria in the field strain of Haemonchus contortus. Adult female worms were collected from the abomasa of sheep. DNA was extracted from adult female worms and parasite eggs laid in vitro using long or shorter enzymatic incubation methods. Polymerase Chain Reaction (PCR) was performed using universal bacterial and phylum Firmicutes-specific primers; PCR products were cloned and sequenced. The analysis of the sequences shows a majority of the sequences belong to rumen bacteria, mainly Ruminococcus. Streptococcus was detected in four eggs, and adult worm samples and the sequences had a very high homology to the Streptococcus sequences in the database. Clostridium was detected only in the adult samples, whereas Nevskia and Pseudomonas were detected only in the egg samples. Three antibiotics, Ampicillin (Amp), Gentamycin (Gen) and Tetracycline (Tet), individually or combination, were tested to establish proof of concept that abomasal nematode parasites can be controlled by killing the resident bacteria. A larval migration inhibition assay was used to test the hypothesis. Tet (10 and 20 mM) resulted in around 30% mortality in larvae. Amp and Gen did not result in significant levels of larval mortality but, when given in combination, resulted in significant mortality of the larvae, suggesting the role of antibiotics in controlling the parasites by targeting the resident bacteria