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To explain irradiation creep, several mechanisms have been proposed. Some are based on the effect of stress on either nucleation or growth of dislocation loops. To investigate these mechanisms in aluminum we combine in-situ transmission electron microscope irradiation under stress and two simulation approaches (object kinetic Monte-Carlo, molecular dynamics Frenkel pair accumulation). We observe the selectivity of Frank loop variants under electron irradiation and applied stress. When the stress is turned on after loop formation, there is no loop variant selectivity, suggesting the absence of preferential absorption on already formed loops. Object kinetic Monte-Carlo simulations, including the effect of stress on the diffusion of point defects, show no growth rate difference between loop variants. Frenkel pair accumulation simulations exhibit variant selectivity of nucleated loops. This shows that loop selectivity is due to preferential nucleation of well oriented loops under stress and not to differential growth of loops. [ABSTRACT FROM AUTHOR]

[Display omitted] We investigate the influence of elastic properties of point defects on dislocation climb under stress and irradiation. For this purpose, elastic dipole tensors and diaelastic polarizabilities are evaluated in aluminum for vacancies and self-interstitial atoms in their stable and saddle configurations, using density functional theory calculations. These parameters are introduced in an object kinetic Monte-Carlo code and a continuous diffusion model to estimate the stress dependence of dislocation climb, using a dipole of straight dislocations. We show that both parameters have an influence on absorption of point defects under stress, in agreement with previous analytical models. However, the effect of dipole tensor is found only 5 times larger than polarizability, whereas models predict a factor up to 30. In addition, including polarizability reverses the stress angular dependence when a uniaxial stress is applied orthogonal to the dislocation line, so in general polarizability cannot be ignored for simulations under applied stress. Further comparison with analytical models shows that they give a good description of angular dependence, provided saddle point configuration of point defects is not too anisotropic. For vacancies, which are strongly anisotropic in their saddle configuration, models fail to reproduce quantitatively lattice effects on stress angular dependence observed in simulations. Calculations show that dislocation climb velocity under irradiation is expected to be the highest if the stress is approximately orthogonal to the dislocation line, especially along the Burgers vector, and the lowest if the stress is applied close to the 〈 100 〉 direction with the largest projection on the dislocation line. [ABSTRACT FROM AUTHOR]

Notre objectif principal était de décrire les caractéristiques des actes auto-agressifs avec substance des sujets de moins de 18 ans pris en charge dans le cadre de la régulation téléphonique d'urgence du centre antipoison et de toxicovigilance de Marseille. Cette étude est descriptive, prospective et quantitative. Elle est monocentrique et a été réalisée au sein du centre antipoison et de toxicovigilance de Marseille. Elle a inclus l'ensemble des sujets de moins de 18 ans pour lesquels un avis au centre antipoison et de toxicovigilance de Marseille a été sollicité au décours d'un acte auto-agressif avec une substance toxique (dont des médicaments) entre le 1er octobre 2021 et le 31 janvier 2022. Les 308 sujets inclus étaient âgés de 11 à 17 ans avec un âge moyen de 14,9 ans (±1,5) pour les filles et 14,6 (±1,7) pour les garçons (p = 0,234). Le sex-ratio était de 0,14. Deux cent quarante patients (77,9 %) avaient déjà un suivi antérieur psychologique ou psychiatrique. Il s'agissait d'une récidive de tentative de suicide dans 43,8 % des cas (n = 135). Le recours aux services des urgences était quasiment systématique (n = 277, 89,9 %). Il s'agissait en majorité de mono-intoxications (n = 193, 62,7 %). Les intoxications étaient dans la plupart des cas médicamenteuses (n = 281, 91,2 %). Les antalgiques-antipyrétiques étaient la classe médicamenteuse la plus utilisée (n = 147 patients, 47,7 %), suivis par les anxiolytiques (n = 62, 20,1 %). Le paracétamol s'est avéré la substance la plus ingérée (n = 108, 35,1 %). Cent six patients sont restés asymptomatiques (34,4 %). Sur les 308 sujets inclus, 78,6 % étaient hospitalisés pour une durée moyenne de 4 ans jours. Deux cent quarante-neuf jeunes (80,8 %) avaient eu au moins un avis psychiatrique et 200 (64,9 %) avaient un rendez-vous pour une consultation psychiatrique à la sortie. Les caractéristiques démographiques des jeunes suicidants et celles de l'intoxication étaient globalement similaires à celles retrouvées dans la littérature. Le taux de récidive est plus élevé que dans la littérature. Plus de deux ans après le début de la pandémie de SARS-CoV-2, le mal-être de la jeunesse est toujours là alors que l'offre de soin est déjà saturée. Pour inverser la tendance d'ici 2027, le ministère de la Santé et de la Prévention a actualisé sa stratégie nationale de prévention par différents moyens. Une étude au décours pourrait être intéressante pour voir l'impact de ces mesures. Cette étude, même limitée dans le temps et l'espace, complète d'autres indicateurs peu nombreux et partiels, et montre que la crise de santé mentale pédiatrique s'aggrave, en particulier chez les plus jeunes adolescents, avec un taux de récidive qui augmente. Il faut rester vigilant et continuer à mettre en place des actions de dépistage et des moyens de prévention notamment des récidives. To describe poison exposures in case of self-poisoning subjects younger than 18 years old reported to the Marseille Poison Control Center. This is a descriptive, monocentric and prospective review of self-poisoning patients aged < 18 years who reported to the Marseille Poison Control Center from 1st October 2021 to 31st January 2022. The 308 subjects included were aged 11 to 17 years with an average age of 14.9 years (±1.5) for girls and 14.6 (±1.7) for boys (P = 0.234). The sex ratio was 0.14. Two hundred and forty patients (77.9%) already had prior psychological or psychiatric follow-up. It was a recurrence of suicide attempts in 43.8% of cases (n = 135). The use of an emergency department was almost systematic (n = 277, 89.9%). Most of these were mono-intoxications (n = 193, 62.7%). The poisonings were in most cases drug-induced (n = 281, 91.2%). Analgesics-antipyretics were the most used drug class (n = 147 patients, 47.7%), followed by anxiolytics (n = 62, 20.1%). Paracetamol proved to be the most ingested substance (n = 108, 35.1%). One hundred and six patients remained asymptomatic (34.4%). Of the 308 cases included, 78.6% were hospitalized for an average of four days. Two hundred forty-nine cases (80.8%) had one psychiatric evaluation in an emergency department and 200 (64.9%) will have an appointment for a psychiatric consultation on discharge. The demographic characteristics of young suicides and those of intoxication were globally like those found in the literature although our recurrence rate was higher than those in the literature. More than two years after the start of the SARS-CoV-2 pandemic, the malaise of young people remains while the care offer is already saturated. To reverse the trend by 2027 the French Ministry of Health and Prevention has updated its national prevention strategy by various means. A subsequent study could be interesting to see the impact of these measures. This study is limited but seems to complement some indicators, which shows that the pediatric mental health crisis is worsening, especially among the youngest adolescents who have an increased recurrence rate. We must remain vigilant and continue to implement screening actions and means of prevention, particularly of recurrences. [ABSTRACT FROM AUTHOR]