Use of resonance Raman spectroscopy to study the phase diagram of PbZr0.52Ti0.48O3

Evidence is presented for the first time that the sharp and continuous spectral changes observed in PbZr0.52Ti0.48O3 (PZT) between 350 and 10 K with the 647.1 nm wavelength are due to a resonance Raman effect. Such a phenomenon can be explained by means of a self-trapped exciton emission oxygen deficient complex (TiTi' - VO-) of PZT powder whose energy is close to the radiation line of the laser. This kind of approach should also be very useful to distinguish the phase transition sequence for other related ferro/ piezoelectric systems

Dielectric investigations of PZT under high pressures and low temperatures

International audienc

Comportements auto-dommageables sans intention suicidaire et conduites suicidaires chez les jeunes: une revue de littérature narrative à la lumière du modèle d’Hamza et al. (2012)

Les comportements auto-dommageables sans intention suicidaire (CADSIS) et les conduites suicidaires (CS), incluant le suicide accompli, sont des problèmes de santé publique majeurs chez les adolescents et les jeunes adultes. Ils sont constatés de manière ubiquitaire, aussi bien dans des populations cliniques que communautaires. Bien que ces deux comportements coexistent fréquemment, les distinguer clairement reste complexe. En effet, les différences entre CADSIS et CS ont été davantage investiguées que leurs liens sous-jacents, tout comme les facteurs contribuant à la transition entre CADSIS et CS. Cette revue de littérature narrative vise à rendre compte de l’état actuel des connaissances concernant les articulations entre CADSIS et CS, à la lumière du modèle intégré de Hamza et al. qui propose des hypothèses de liens entre ces comportements. En addition à cet article, notre revue se base sur des articles postérieurs ou non-cités par Hamza et al., décrivant des études transversales, longitudinales et des méta-analyses ciblant les liens et/ou les différences entre CADSIS et CS chez des adolescents et jeunes adultes âgés de 12 à 25 ans. Au vu des différents résultats, le modèle d’Hamza et al. est intéressant car il intègre des facteurs de risques communs et une forme d’habituation pour expliquer la progression fréquente des CADSIS vers des CS. Cependant, si cette trajectoire est fréquente, elle n’est pas la règle. Il s’agirait dès lors de tester les liens et variables qui caractérisent potentiellement la relation CADSIS-CS selon leur modèle.Non-suicidal self-injuries (NSSI) and suicidal conduct (SC), including completed suicide, are major public health problems among adolescents and young adults. They are seen ubiquitously in both clinical and community populations. Although these two behaviors frequently co-exist, distinguishing them clearly remains complex. Indeed, the differences between NSSI and CS have been investigated more than their underlying relationships, as have the factors contributing to the transition between NSSI and CS. This narrative literature review aims to report on the current state of knowledge regarding the articulations between NSSI and CS, in light of Hamza et al.’s integrated model that proposes hypotheses of links between these behaviors. In addition to this article, our review is based on later articles or articles not cited by Hamza et al., describing cross-sectional, longitudinal, and meta-analyses targeting the links and/or differences between CADSIS and CS in adolescents and young adults aged 12 to 25 years. Based on the various findings, Hamza et al.’s model seems interesting because it incorporates common risk factors and a form of habituation to explain the frequent progression from CADSIS to CS. However, if this trajectory is frequent, it is not the rule. It would therefore be necessary to test all the links and variables that potentially mediate the CADSIS-CS relationship according to their model

Low-symmetry phases at the tilt boundary of the Pb„Zr1−xTix...O3 solid solution

International audienceThe tilt boundary that separates the well-known rhombohedral phases R3m and R3c of the Pb_Zr1−xTix_O3 solid solution was investigated by means of time-of-flight neutron powder diffraction, dielectric measurements, and resonance Raman spectroscopy. Careful Rietveld refinements yield significantly better agreement factors using monoclinic models for the long-range structure of PbZr0.6Ti0.4O3 with a Cc space group at low temperature and with a Cm space group at high temperature rather than the widely accepted rhombohedral symmetry. The spontaneous polarization was found to lie along the pseudocubic _112_ direction instead of along the _111_ direction. This polarization direction is shown to be adopted for a wide variety of compositions, temperatures, and pressures and has major implications for the domain structure of these materials. Furthermore, the transition between the untilted and the tilted structures was found to be very diffuse and strongly dependent on the thermal history of the sample

A case of coexistent acute severe alcoholic and Q fever hepatitis: The useful contribution of repeated liver biopsies

Acute Q fever is a worldwide zoonotic infection due to C. burnetii that may be associated with hepatitis. Nonspecific clinical and biological manifestations may accompany liver involvement, including hepatomegaly and elevated liver biological tests. However, the presence of jaundice is rare. Therefore, making a diagnosis of Q fever hepatitis may be difficult in an afebrile patient with jaundice of recent onset, altered liver function tests, excessive alcohol intake and no reported contact with animals. We report here the diagnostic work-up and complex clinical management of a patient presenting with acute hepatitis resulting from both C. burnetii infection and severe alcoholic steatohepatitis. Positive serology together with a detailed examination of the liver biopsy was able to reveal the coexistence of both Q fever hepatitis with typical fibrin-ring granulomas as well as florid lesions of alcoholic steatohepatitis. A combination of antibiotics, hydroxychloroquine and steroids, guided by the helpful description of changes in histological alterations on repeated liver biopsies during the course of the disease contributed to the slow but favorable outcome

Autour de la performance

Il y a quarante ans fut publié, dans la revue Langages (1970), le premier manifeste de l'ethnolinguistique française et Geneviève Calame-Griaule participait activement à la naissance de ce mouvement, par son approche originale de la littérature orale. C'est pourquoi Autour de la performance, soixante-cinquième numéro des Cahiers de littérature orale, dont Geneviève Calame-Griaule a été la fondatrice, se veut à la fois un témoignage et un hommage adressé à cette dernière. L'impact de son livre Ethnologie et Langage (1965) a, en effet, été considérable non seulement sur les recherches française, mais aussi anglo-saxonnes, notamment sur les partisans du courant de l'ethnography of speaking and communication, dont les fondateurs les plus connus sont Dell Hymes et William Labov. Ce numéro réexamine, à travers cinq études de cas, les modes de relations de l'énonciateur (ou locuteur selon les théories) au dispositif énonciatif. Il s'agit ainsi d'une application approfondie des éléments constitutifs de la performance et de leurs interactions, dans la perspective de l'approche ethnolinguistique de la littérature orale définie par Geneviève Calame-Griaule : énonciateur, auditoire, espace et temps. Autour de la performance, centré sur des exemples de littérature orale africaine en hommage à l'africaniste Geneviève Calame Griaule, voudrait apporter quelques éléments de réflexion à tous ceux qui s'intéressent à l'oralité