EBSD coupled to SEM in situ annealing for assessing recrystallization and grain growth mechanisms in pure tantalum

International audienceAn in situ annealing stage has been developed in-house and integrated in the chamber of a Scanning Electron Microscope equipped with an Electron BackScattered Diffraction system. Based on the Joule effect, this device can reach the temperature of 1200°C at heating rates up to 100°C/s, avoiding microstructural evolutions during heating. A high-purity tantalum deformed sample has been annealed at variable temperature in the range 750°C-1030°C, and classical mechanisms of microstructural evolutions such as recrystallization and grain coarsening phenomena have been observed. Quantitative measurements of grain growth rates provide an estimate of the mean grain boundary mobility, which is consistent with the value estimated from physical parameters reported for that material. In situ annealing therefore appears to be suited for complementing bulk measurements at relatively high temperatures, in the context of recrystallization and grain growth in such a single-phase material

Effect of grain orientation on the development of dislocation substructures during cold-deformation of pure Tantalum. Link with static recrystallization and recovery.

International audienceRecrystallization and recovery of pure polycrystalline tantalum are highly influenced by the intragranular dislocation structure developed during plastic deformation. A tantalum oligocrystal has been deformed by compression at room temperature. The resulting intragranular dislocation structures have been characterized using a FEG scanning electron microscope coupled with an EBSD system. Based on these experimental observations and crystal plasticity simulations, the development of dislocation substructures is related to the crystallographic stability of grain orientations

Mesures des hétérogénéités de déformation du tantale déformé à froid et conséquences sur la recristallisation

National audienceLa recristallisation statique du tantale est fortement dépendante de la microstructure engendrée lors de la mise en forme. Des échantillons présentant de faibles taux de déformation ont été obtenus par des essais mécaniques simples de torsion et de compression. Leur observation par microscopie électronique à balayage ainsi que la réalisation de cartographies d'orientation par EBSD, associées à des traitements thermiques in situ, ont permis de montrer qu'un grain avec un facteur de Taylor élevé recristallisait plus vite. Par ailleurs, une méthode « globale » d'évaluation de la densité de dislocations à partir de mesures de dureté a été mise en place. Elle permet d'estimer l'énergie stockée par le matériau lors de sa déformation, énergie qui peut ensuite être reliée au déclenchement de la recristallisation. Cette approche est particulièrement intéressante pour des échantillons déformés sévèrement suivant un chemin de déformation complexe, pour lesquels le calcul des facteurs de Taylor à partir d'une microstructure déformée revêt moins de sens

THERMIDE : un programme de recherche pour optimiser les opérations de mise en forme et de traitements thermiques de composants métalliques

L'objectif du programme THERMIDE est d'optimiser le procédé de fabrication des composants métalliques par une meilleure maîtrise des déformations et le contrôle de la taille de grain. Devant la complexité du problème, une attention particulière est portée à la modélisation de la recristallisation dynamique activée durant la déformation à chaud des métaux. Les applications portent sur différentes nuances d'acier pour composants nucléaires ainsi qu'un matériau « école » (le tantale). La simulation d'un traitement thermique est également abordée dans l'intention de valider le logiciel FORGE®

Political determinants of the fiscal sustainability: evidence from six individual developed countries.

This paper aims at assessing the fiscal sustainability and its political determinants in six countries, namely France, Germany, Greece, Italy, the United Kingdom, the United States. First, using the recent sustainability approach of Bohn (1998) based on fiscal reaction function, econometric findings using OLS reveal a positive response of the primary surplus to changes in debt in several countries. In other words, fiscal policy is sustainable in France, Italy, the United Kingdom, the United States, but not in Germany and Greece. Second, by introducing political dummy variables, we test the electoral budget cycle, the partisan cycle and the government coalition theories. We find the presence of electoral and partisan cycle in France, Greece, Italy but not in the rest of our countries

Religion et Politique

À travers l'analyse d'exemples de la relation politique/religion, ce dossier de Terrain souhaite réfléchir sur les diverses configurations de cette relation : mouvements religieux pour la paix, manifestation mariale dans le contexte multiconfessionnel du Liban, affrontements religieux au cours de la guerre en ex-Yougoslavie, évocation de « martyrs » dans la définition de la nation ukrainienne, création de rituels religieux autour de victimes civiles de la Mafia sicilienne..

Did the COVID-19 pandemic delay treatment for localized breast cancer patients? A multicenter study.

BackgroundLonger times between diagnosis and treatments of cancer patients have been estimated as effects of the COVID-19 pandemic. However, relatively few studies attempted to estimate actual delay to treatment at the patient level.ObjectiveTo assess changes in delays to first treatment and surgery among newly diagnosed patients with localized breast cancer (BC) during the COVID-19 pandemic.MethodsWe used data from the PAPESCO-19 multicenter cohort study, which included patients from 4 French comprehensive cancer centers. We measured the delay to first treatment as the number of days between diagnosis and the first treatment regardless of whether this was neoadjuvant chemotherapy or surgery. COVID-19 pandemic exposure was estimated with a composite index that considered both the severity of the pandemic and the level of lockdown restrictions. We ran generalized linear models with a log link function and a gamma distribution to model the association between delay and the pandemic.ResultsOf the 187 patients included in the analysis, the median delay to first treatment was 42 (IQR:32-54) days for patients diagnosed before and after the start of the 1st lockdown (N = 99 and 88, respectively). After adjusting for age and centers of inclusion, a higher composite pandemic index (> = 50 V.S. ConclusionWe found evidence of no direct impact of the pandemic on the actual delay to treatment among patients with localized BC

Anosmia but Not Ageusia as a COVID-19-Related Symptom among Cancer Patients—First Results from the PAPESCO-19 Cohort Study

International audienceBackground: Cancer patients may fail to distinguish COVID-19 symptoms such as anosmia, dysgeusia/ageusia, anorexia, headache, and fatigue, which are frequent after cancer treatments. We aimed to identify symptoms associated with COVID-19 and to assess the strength of their association in cancer and cancer-free populations. Methods: The multicenter cohort study PAPESCO-19 included 878 cancer patients and 940 healthcare workers (HCWs). At baseline and quarterly thereafter, they reported the presence or absence of 13 COVID-19 symptoms observed over 3 months and the results of routine screening RT-PCR, and they were systematically tested for SARS-CoV-2-specific antibodies. We identified the symptom combinations significantly associated with COVID-19. Results: Eight percent of cancer patients were COVID-19 positive, and 32% were symptomatic. Among the HCWs, these proportions were 9.5 and 52%, respectively. Anosmia, anorexia, fever, headache, and rhinorrhea together accurately discriminated (c-statistic = 0.7027) COVID-19 cases from cancer patients. Anosmia, dysgeusia/ageusia, muscle pain, intense fatigue, headache, and chest pain better discriminated (c-statistic = 0.8830) COVID-19 cases among the HCWs. Anosmia had the strongest association in both the cancer patients (OR = 7.48, 95% CI: 2.96–18.89) and HCWs (OR = 5.71, 95% CI: 2.21–14.75). Conclusions: COVID-19 symptoms and their diagnostic performance differ in the cancer patients and HCWs. Anosmia is associated with COVID-19 in cancer patients, while dysgeusia/ageusia is not. Cancer patients deserve tailored preventive measures due to their particular COVID-19 symptom pattern

COVID-19 Infection despite Previous Vaccination in Cancer Patients and Healthcare Workers: Results from a French Prospective Multicenter Cohort (PAPESCO-19)

International audienceIn a multicenter prospective cohort of cancer patients (CP; n = 840) and healthcare workers (HCWs; n = 935) vaccinated against COVID-19, we noticed the following: i/after vaccination, 4.4% of HCWs and 5.8% of CP were infected; ii/no characteristic was associated with post-vaccine COVID-19 infections among HCWs; iii/CP who developed infections were younger, more frequently women (NS), more frequently had gastrointestinal, gynecological, or breast cancer and a localized cancer stage; iv/CP vaccinated while receiving chemotherapy or targeted therapy had (NS) more breakthrough infections after vaccination than those vaccinated after these treatments; the opposite was noted with radiotherapy, immunotherapy, or hormonotherapy; v/most COVID-19 infections occurred either during the Alpha wave (11/41 HCW, 20/49 CP), early after the first vaccination campaign started, or during the Omicron wave (21/41 HCW, 20/49 CP), more than 3 months after the second dose; vi/risk of infection was not associated with values of antibody titers; vii/the outcome of these COVID-19 infections after vaccination was not severe in all cases. To conclude, around 5% of our CPs or HCWs developed a COVID-19 infection despite previous vaccination. The outcome of these infections was not severe