Cédric Audebert, La diaspora haïtienne. Territoires migratoires et réseaux transnationaux

Le dernier ouvrage de Cédric Audebert s'inscrit dans la continuité de ses précédentes publications et de ses recherches sur les mouvements migratoires depuis Haïti. Il dépasse ici les analyses qui portent sur des contextes précis d'émigration ou d'immigration pour proposer un panorama général des dynamiques sociales et spatiales qui construisent l'espace migratoire haïtien. Cette démarche est primordiale pour l'auteur qui soutient qu'il est impossible de comprendre la société haïtienne et d'..

Transformations urbaines et Migrations dans les villes espagnoles

Les 8 et 9 décembre 2011, deux journées d’étude portant sur le thème des « transformations urbaines et migrations dans les villes espagnoles » se sont déroulées dans les locaux de la MSHS de l’Université de Poitiers. Organisée par Naïk Miret (Migrinter), cette rencontre a rassemblé pour la quatrième fois consécutive des chercheurs de plusieurs disciplines. Au travers de cas de villes espagnoles marquées par l’arrivée massive de migrants internationaux depuis la décennie 1990, les intervenants..

Rencontre dans la diversité. 4e Congrès de l'Association européenne des sciences de l'occupation (OSE), à Hildesheim, Allemagne, du 8 au 9 septembre 2017

Sans résumé

Le recrutement et la fidélisation des bénévoles retraités par les associations

National audienceEn raison du temps libre engendré par l’arrêt de l’activité professionnelle, les retraités deviennent une cible très convoitée par les associations à la recherche de bénévoles. Cependant, ils sont souvent considérés comme un segment homogène, d’où des difficultés de recrutement et de fidélisation par les associations. Pour y remédier, cet article propose une typologie de bénévoles retraités sur la base de leurs motivations et de caractéristiques psychosociales liées au vieillissement. Cinq profils se dégagent : les hédonistes, les coupables, les affectifs, les soucieux de postérité, les ambitieux. Reste aux associations à cibler un ou plusieurs profils selon la fonction à pourvoir et à adapter leurs campagnes de communication en conséquence

Effect of the deposition route on the microstructure of plasma-sprayed hydroxyapatite coatings

Plasma-spray (PS) is the most common technique used to cover orthopaedic titanium-based implant surfaces with hydroxyapatite (HA - Ca10(PO4)6OH2). The objective of the current work was to explore the influence of the precursor nature and characteristics (mainly powder size, Ca/P ratio, and density) on the morphology and the microstructure of HA coatings, deposited either by conventional atmospheric plasma spray (APS) or by rf-suspension plasma spray (rf-SPS). Two powders with different size distribution, density and shape were sprayed with same operating APS conditions. In parallel two water-based suspensions with distinct particle size and chemistry (Ca/P ratio) were implemented in rf-SPS. The morphology of both APS and rf-SPS coatings observed by SEM exhibits micro and sub-micro sized structures respectively, with similar porosity and thickness. The difference in precursor particle size does not affect the coating structure in rf-SPS, unlike in APS conditions. Superimposition of topography and phases maps performed from profilometry and Raman cartographies showed no direct correlation between the surface profile and composition. But such analysis highlighted the heterogeneity of the phases composing the coating surface, opening the possibility of a better understanding of biological behaviour

Hox genes define distinct progenitor sub-domains within the second heart field

AbstractMuch of the heart, including the atria, right ventricle and outflow tract (OFT) is derived from a progenitor cell population termed the second heart field (SHF) that contributes progressively to the embryonic heart during cardiac looping. Several studies have revealed anterior-posterior patterning of the SHF, since the anterior region (anterior heart field) contributes to right ventricular and OFT myocardium whereas the posterior region gives rise to the atria. We have previously shown that Retinoic Acid (RA) signal participates to this patterning. We now show that Hoxb1, Hoxa1, and Hoxa3, as downstream RA targets, are expressed in distinct sub-domains within the SHF. Our genetic lineage tracing analysis revealed that Hoxb1, Hoxa1 and Hoxa3-expressing cardiac progenitor cells contribute to both atria and the inferior wall of the OFT, which subsequently gives rise to myocardium at the base of pulmonary trunk. By contrast to Hoxb1Cre, the contribution of Hoxa1-enhIII-Cre and Hoxa3Cre-labeled cells is restricted to the distal regions of the OFT suggesting that proximo-distal patterning of the OFT is related to SHF sub-domains characterized by combinatorial Hox genes expression. Manipulation of RA signaling pathways showed that RA is required for the correct deployment of Hox-expressing SHF cells. This report provides new insights into the regulatory gene network in SHF cells contributing to the atria and sub-pulmonary myocardium

Dynamical modeling of bi-layer Aluminium adhesive tape for laser shock applications

The presented work covers the response of Aluminium tape (Al tape) under high strain rate of deformation (order of 106s−1) using laser shock. High power laser (J) with a short pulse duration (ns) is used to create laser shock within the water confinement regime on two Al tape configurations in order to apply low and high pressure (order of MPa and GPa). Al tape has been modeled using Johnson-Cook (J-C) material model for the Al layer, and Steinberg–Cochran–Guinan (SCG) material model (elastic with pressure dependence) for the adhesive layer, both material models are coupled with Grüneisen equation of state. The Al tape model has been validated by comparing the simulated Back Face Velocity (BFV) of the target with the measured one by the Velocity Interferometer System for Any Reflector (VISAR). In addition, the validated material model is used to conduct the sensitivity studies about the transmitted pressure depending on the acoustical impedance of the target and adhesive thickness. Moreover, location and magnitude of maximum tensile stress within the target are calculated in function of the adhesive thickness of the Al tape. Finally, it has been proved that using one laser beam configuration, maximum tensile zone could appears close to the front face by increasing the adhesive thickness

Laser induced plasma characterization in direct and water confined regimes: new advances in experimental studies and numerical modelling

Optimization of the laser shock peening (LSP) and LASer Adhesion Test (LASAT) processes requires control of the laser-induced target's loading. Improvements to optical and laser technologies allow plasma characterization to be performed with greater precision than 20 years ago. Consequently, the processes involved during laser-matter interactions can be better understood. For the purposes of this paper, a self-consistent model of plasma pressure versus time is required. The current approach is called the inverse method, since it is adjusted until the simulated free surface velocity (FSV) corresponds to the experimental velocity. Thus, it is not possible to predict the behavior of the target under shock without having done the experiments. For the first time, experimental data collected in different labs with the most up-to-date laser parameters are used to validate a self-consistent model for temporal pressure-profile calculation. In addition, the parameters characterizing the plasma (temperature, thickness and duration) are obtained from the ESTHER numerical code, together with the amount of ablated matter. Finally, analytic fits are presented that can reproduce any pressure-temporal profiles in the following domains of validity: Intensities, I, ranging from 10 to 500 GW cm-2 and pulse durations, T pul, between 5 and 40 ns for the direct-illumination regime at 1053 nm, I ranging from 1 to 6 GW cm-2 and T pul between 10 to 40 ns in the water-confined regime at 1053 nm, and I from 1 to 10 GW cm-2 and T pul between 7 and 20 ns in the water-confined regime at 532 nm. These temporal pressure profiles can then be used to predict the aluminum target's behavior under laser shock using mechanical simulation software