La quête des origines face à la loi du secret

Au début de la Troisième République, l’Assistance publique de Paris recueille chaque année environ 3 000 enfants abandonnés. Séparés d’une famille dont ils ne gardent aucun souvenir, ces jeunes grandissent dans l’ignorance de leurs origines, conformément à la loi et à la culture administrative de l’institution. L’identité de leurs parents, les motifs et les circonstances de leur abandon sont pourtant des énigmes qui hantent la plupart d’entre eux, et dont ils imaginent que l’administration détient toutes les clés. Leur correspondance avec le directeur de l’Assistance publique témoigne de cette douloureuse obsession, et laisse apparaître le roman que ces enfants sans famille se sont parfois inventé pour combler les silences de leur histoire personnelle. Elle révèle aussi la diversité des stratégies épistolaires mises en place pour infléchir la règle du secret, ainsi que les circonstances de cette prise d’écriture qui rythme les étapes importantes de leur vie de jeunes adultes : service militaire, majorité, mariage ou naissance de leur premier enfant.The Search for origins Children of the French Assistance Publique in search of their personal history (1900-1920) At the beginning of the Third Republic, services of the Paris Assistance Publique collected about 3 000 abandoned children a year from the streets. Separated from a family of which they had no memory, these children grew up ignorant of their origins, in accordance with the law and the administrative culture of the institution. The identity of their parents and the motives and circumstances of their abandonment were enigmas plaguing most of them, convinced as they were that the administration knew where they came from. Their correspondence with the Director of the Assistance Publique bears evidence of this painful obsession. It discloses the fiction these children without families made up to fill in the gaps of their biographies. It also reveals the various epistolary strategies implemented to bypass the confidentiality rules and the circumstances of their adulthood in which they penned their milestones – entering the army, reaching majority, getting married or having their first child

Fabrice Virgili, Naître ennemi. Les enfants de couples franco-allemands nés pendant la seconde guerre mondiale

Depuis quelques années, l’historiographie des conflits du xxe siècle s’est largement intéressée à la figure de l’ennemi. À partir de sources diverses (journaux, romans, affiches, chansons, dessins) elle s’est attachée à décrire et à comprendre la façon dont chaque camp percevait celui d’en face. L’ouvrage que Fabrice Virgili consacre aux enfants nés de couples franco-allemands pendant la seconde guerre mondiale apporte une intéressante contribution à cette histoire des représentations, mais i..

Fabrice Virgili, Naître ennemi. Les enfants de couples franco-allemands nés pendant la seconde guerre mondiale

Depuis quelques années, l’historiographie des conflits du xxe siècle s’est largement intéressée à la figure de l’ennemi. À partir de sources diverses (journaux, romans, affiches, chansons, dessins) elle s’est attachée à décrire et à comprendre la façon dont chaque camp percevait celui d’en face. L’ouvrage que Fabrice Virgili consacre aux enfants nés de couples franco-allemands pendant la seconde guerre mondiale apporte une intéressante contribution à cette histoire des représentations, mais i..

Specific heat capacity and thermal conductivity of PEEK/Ag nanoparticles composites determined by Modulated-Temperature Differential Scanning Calorimetry

The thermal conductivity accurate measurement of polymer based composites is a challenge: it would allow us to understand the mechanisms of thermal transport in such materials. Silver nanoparticles were introduced in Polyetheretherketone matrix and their influence on thermal properties was studied. Thermal conductivity and specific heat capacity of composites were determined by Modulated-Temperature Differential Scanning Calorimetry and analysed as a function of particles volume content and temperature. The specific heat capacity of the composites decreases with increasing silver particles content below the electrical percolation threshold. Above the electrical percolation threshold the specific heat capacity decreases more slowly and converge toward the specific heat capacity of compressed silver nanoparticles. The evolution of the thermal conductivity with filler content exhibits a non-linear profile. Experimental data are coherent with the Maxwell model suggesting continuity of the polymer matrix and a contribution of the silver particles to the effective thermal conductivity greater than volume effect. The temperature dependence of the composites thermal conductivity is characteristic of amorphous phase, while a transition from vitreous-like to crystalline-like behaviour of the specific heat capacity is observed with the introduction of metallic particles

Thermal, mechanical and dielectric behaviour of poly(aryl ether ketone) with low melting temperature

New poly(aryl ether ketone)s (PAEKs) with a low melting temperature (relative to PEEK) are of interest in order to simplify the manufacturing of high-performance polymers or composites. In this study, we propose to investigate the physical properties of a new PAEK from Victrex, namely PAEK LM. Combinations of thermal analyses were used as follows: standard and modulated temperature differential scanning calorimetry, dynamic mechanical analysis, dynamic dielectric analysis and guarded hot plate technique. We found that the global mechanical, dielectric and thermal properties are very similar to the PEEK reference. The glass transition temperature was observed in the same range than PEEK (∼ 150 °C) while the melting temperature Tm was measured at 307 °C for PAEK LM which is about 35 °C below the melting temperature of PEEK. The degree of crystallinity of PAEK LM was found to be 27% while for PEEK it is 38%, depending on the processing conditions. This work explored crystalline structure–property relationships to explain the behaviour of PAEK LM

Silver fillers aspect ratio influence on electrical and thermal conductivity in PEEK/Ag nanocomposites

The development of polymer based conductive composites is required in aeronautical applications where electrostatic charges and heat need to be evacuated. Optimization of conductive filler content is necessary to maintain low density and high mechanical properties provided by the polymer matrix. We introduced silver nanoparticles in Polyetheretherketone. Electrical conductivity, specific heat capacity, thermal conductivity and thermal diffusivity have been determined as a function of filler content and temperature. In particular, we studied the influence of silver nanoparticles aspect ratio on these thermal properties. We compared nanospheres with nanowires. A low electrical percolation threshold (0.55 vol%) is obtained for silver nanowires composites compared to spherical particles (10.8 vol%). Thermal conductivity increases with silver content and the influence of filler aspect ratio is interesting: thanks to nanowires, the thermal conductivity enhancement is reached for lower silver content. Experimental data are well fitted with Nan model. Specific heat capacity decreases with the introduction of silver nanoparticles, following the mixture rule independently of aspect ratio. Composites thermal diffusivity also increases with increasing silver content and influence of filler aspect ratio can be brought to light. Temperature dependence of these thermal properties indicate a dominant heat transport mechanism typical of disordered materials

Staphylococcus aureus virulence and metabolism are dramatically affected by Lactococcus lactis in cheese matrix

International audienceIn complex environments such as cheeses, the lack of relevant information on the physiology and virulence expression of pathogenic bacteria and the impact of endogenous microbiota has hindered progress in risk assessment and control. Here, we investigated the behaviour of Staphylococcus aureus, a major foodborne pathogen, in a cheese matrix, either alone or in the presence of Lactococcus lactis, as a dominant species of cheese ecosystems. The dynamics of S. aureus was explored in situ by coupling a microbiological and, for the first time, a transcriptomic approach. Lactococcus lactis affected the carbohydrate and nitrogen metabolisms and the stress response of S. aureus by acidifying, proteolysing and decreasing the redox potential of the cheese matrix. Enterotoxin expression was positively or negatively modulated by both L. lactis and the cheese matrix itself, depending on the enterotoxin type. Among the main enterotoxins involved in staphylococcal food poisoning, sea expression was slightly favoured in the presence of L. lactis, whereas a strong repression of sec4 was observed in cheese matrix, even in the absence of L. lactis, and correlated with a reduced saeRS expression. Remarkably, the agr system was downregulated by the presence of L. lactis, in part because of the decrease in pH. This study highlights the intimate link between environment, metabolism and virulence, as illustrated by the influence of the cheese matrix context, including the presence of L. lactis, on two major virulence regulators, the agr system and saeRS

Spatiotemporal changes in surface sediment characteristics and benthic macrofauna composition off the Rhône River in relation to its hydrological regime

International audienceThe consequences of changes in the water flow of the Rhône River on surface sediment characteristics and benthic macrofauna composition were assessed within 3 distinct areas: (1) the delta front, (2) the prodelta, and (3) the distal zone. Five stations were sampled during or closely after: (1) an oceanic flood (April 2007), (2) a generalized flood (May 2008), (3) a Cevenol flood (December 2008), and (4) a dry period (July 2011). Measurements of sediment characteristics included granulometry (D0.5), bulk descriptors of sedimentary organics (OC, TN and THAA), descriptors of labile components of sedimentary organics (chloropigments, EHAA), and both descriptors of origin (Chl-b/Chl-a, C/N) and lability (Chl-a/(Chl-a+Phaeo-a), EHAA/THAA) of sedimentary organics. Sediment Profile Images were collected during April 2007, May 2008 and July 2011. Temporal changes in both sedimentary organics and benthic macrofauna were more important in the delta front and the prodelta than in the distal zone. Bulk characteristics of sedimentary organics presented decreasing inshore/offshore gradients during both April 2007 and July 2011 but not during May and December 2008. There were significant temporal changes in EHAA/THAA at all stations. Changes in benthic macrofauna composition differed between: (1) the delta front and the prodelta, and (2) the distal zone. In the former area, the dry period was associated with establishing a mature community characterized by high abundances and species richness. The best description of spatiotemporal changes in benthic macrofauna composition by surface sediment characteristics was obtained using D0.5, Chl-b/Chl-a, Chl-a/(Chl-a+Phaeo-a) and EHAA, which supports the role of the quality of sedimentary organics in controlling benthic macrofauna composition

What do brain endocasts tell us? A comparative analysis of the accuracy of sulcal identification by experts and perspectives in palaeoanthropology

Palaeoneurology is a complex field as the object of study, the brain, does not fossilize. Studies rely therefore on the (brain) endocranial cast (often named endocast), the only available and reliable proxy for brain shape, size and details of surface. However, researchers debate whether or not specific marks found on endocasts correspond reliably to particular sulci and/or gyri of the brain that were imprinted in the braincase. The aim of this study is to measure the accuracy of sulcal identification through an experiment that reproduces the conditions that palaeoneurologists face when working with hominin endocasts. We asked 14 experts to manually identify well-known foldings in a proxy endocast that was obtained from an MRI of an actual in vivo Homo sapiens head. We observe clear differences in the results when comparing the non-corrected labels (the original labels proposed by each expert) with the corrected labels. This result illustrates that trying to reconstruct a sulcus following the very general known shape/position in the literature or from a mean specimen may induce a bias when looking at an endocast and trying to follow the marks observed there. We also observe that the identification of sulci appears to be better in the lower part of the endocast compared to the upper part. The results concerning specific anatomical traits have implications for highly debated topics in palaeoanthropology. Endocranial description of fossil specimens should in the future consider the variation in position and shape of sulci in addition to using models of mean brain shape. Moreover, it is clear from this study that researchers can perceive sulcal imprints with reasonably high accuracy, but their correct identification and labelling remains a challenge, particularly when dealing with extinct species for which we lack direct knowledge of the brain