First-order ferromagnetic transitions of lanthanide local moments in divalent compounds: An itinerant electron positive feedback mechanism and Fermi surface topological change

Around discontinuous (first-order) magnetic phase transitions the strong caloric response of materials to the application of small fields is widely studied for the development of solid-state refrigeration. Typically strong magnetostructural coupling drives such transitions and the attendant substantial hysteresis dramatically reduces the cooling performance. In this context we describe a purely electronic mechanism which pilots a first-order paramagnetic-ferromagnetic transition in divalent lanthanide compounds and which explains the giant non-hysteretic magnetocaloric effect recently discovered in a Eu$_2$In compound. There is positive feedback between the magnetism of itinerant valence electrons and the ferromagnetic ordering of local $f$-electron moments, which appears as a topological change to the Fermi surface. The origin of this electronic mechanism stems directly from Eu's divalency, which explains the absence of a similar discontinuous transition in Gd$_2$In.Comment: 8 pages, 7 figure

Inter-firm dependency and employment inequalities : Theoretical hypotheses and empirical tests

This article highlights the importance of power relations in inter-firm relations and analyses their impact on firms' employment management practices. We show, firstly, that the use of subcontracting creates a chain of inter-firm economic dependency because it leads the principal contractor to plan and control the activities of the subcontractors. We then advance the hypothesis that this chain of dependency influences both the skill structure and wage levels. Empirical tests carried out on French data confirm that firms that subcontract outsource execution tasks and that the hierarchy of firms impacts employees' wage levels.Subcontracting ; skills ; wages ; power relation

Does subsidising young people to learn to drive promote social inclusion? Evidence from a large controlled experiment in France

We assess the impact of lowering the cost of learning to drive in France by randomly assigning candidates to either of two groups of 18 to 25 years olds. Young people in the “test group” were given a €1000 voucher to pay for their driving lessons and were suported by a welfare centre throughout the time they were learning. Young people in the “control group” retained all the other welfare benefits for the underprivileged. The vouchers were given to 10 000 young people most of whom were not in education, employment or training. We investigate three types of outcome covering driving, housing and employment status. We analyse the specific role of local support in passing the driving test and we specifically take into account the possibility of spillover effects between treated and untreated individuals

Compte-rendu du symposium "Mycotoxines et alimentations"

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Relations de travail et dynamiques des arbitrages des firmes vis-à-vis des dispositifs juridiques : quelles substitutions ?

Ce rapport étudie la dynamique de l'usage de deux formes de mobilisation alternative aux CDI : le CDD comme relation d'emploi et la sous-traitance comme relation de travail. Il propose une quantification de l'évolution de l'usage des CDD et de la sous-traitance entre 1984 et 2000 et formule des hypothèses sur les déterminants du recours par les entreprises qui sont testées à partir des données d'entreprises EAE et DMMO.CDD ; Sous-traitance ; Enquêtes Annuelles d'Entreprises ; droit du travail

Dépendance interentreprises et inégalités d'emploi : hypothèses théoriques et tests empiriques

Cet article met l'accent sur le poids des rapports de force dans les relations interentreprises et analyse leur incidence sur la gestion de l'emploi. Nous montrons tout d'abord que le recours à la sous-traitance, parce qu'il conduit les donneurs d'ordres à planifier et contrôler l'activité des sous-traitants, crée une chaîne de dépendance économique interentreprises. Nous formulons ensuite l'hypothèse que cette chaîne de dépendance influence la structure des qualifications d'une part et le niveau des rémunérations d'autre part. Des tests empiriques menés sur le cas français viennent confirmer ces hypothèses : les entreprises qui sous-traitent externalisent le travail d'exécution et versent des salaires plus élevés à leurs salariés, et ce d'autant plus qu'elles ne sont pas elles-mêmes preneurs d'ordres.Sous-traitance ; Qualifications ; Salaires ; Pouvoir ; Rapport de force

Étude et durabilité de solutions de packaging polymère d'un composant diamant pour l'électronique de puissance haute température

Les besoins en électronique de puissance, de plus en plus exigeants, ont motivé des recherches à l'échelle mondiale sur d'autres matériaux tels que le diamant comme remplaçant du silicium. Nos travaux de recherche sont plus spécifiquement axés sur la définition et la qualification de matériaux polymères capables de garantir l'intégrité des fonctions physiques de modules de puissance en environnement sévère. L'étude concerne la durabilité de candidats polymères à retenir pour le boîtier dont l'objectif est de protéger l'interrupteur de l'environnement extérieur. Suite aux choix des différents polymères étudiés, variables dans leur chimie et leur morphologie (amorphe ou semi-cristallin), un premier objectif scientifique est alors de chercher les relations structures/propriétés permettant de contrôler le procédé de mise en forme des polyimides semi-cristallins et d'en déduire les conditions requises à l'obtention de performances optimisées. Un second objectif a concerné la tenue des différents matériaux sélectionnés en vieillissements isothermes thermo-oxydatifs.Requirements in power electronics are more and more demanding about materials behavior in their operating conditions. This has motivated global scale researches about other materials replacing silicon such as diamond. This study is specifically focusing on the definition and qualification of polymer materials which could preserve physical functions of power modules in severe environments. This study focuses on the durability of several polymers used for the case. This later allows to protect the chip from external environment. The choice of different studied polymers which are dissimilar in chemistry and morphology (i.e. amorphous or semicrystalline) has been made in this study. Then, a first scientific goal was to search the structures/properties relations leading to the control of the manufacturing process of semicrystalline polyimides. A second goal concerned the mechanical strength evaluation of selected materials after thermo-oxidative isothermal ageing.TOULOUSE-INP (315552154) / SudocSudocFranceF

A new subunit vaccine based on nucleoprotein nanoparticles confers partial clinical and virological protection in calves against bovine respiratory syncytial virus

Human and bovine respiratory syncytial viruses (HRSV and BRSV) are two closely related, worldwide prevalent viruses that are the leading cause of severe airway disease in children and calves, respectively. Efficacy of commercial bovine vaccines needs improvement and no human vaccine is licensed yet. We reported that nasal vaccination with the HRSV nucleoprotein produced as recombinant ringshaped nanoparticles (NSRS) protects mice against a viral challenge with HRSV. The aim of this work was to evaluate this new vaccine that uses a conserved viral antigen, in calves, natural hosts for BRSV. Calves, free of colostral or natural anti-BRSV antibodies, were vaccinated with NSRS either intramuscularly, or both intramuscularly and intranasally using MontanideTM ISA71 and IMS4132 as adjuvants and challenged with BRSV. All vaccinated calves developed anti-N antibodies in blood and nasal secretions and N-specific cellular immunity in local lymph nodes. Clinical monitoring post-challenge demonstrated moderate respiratory pathology with local lung tissue consolidations for the non vaccinated calves that were significantly reduced in the vaccinated calves. Vaccinated calves had lower viral loads than the nonvaccinated control calves. Thus NSRS vaccination in calves provided cross-protective immunity against BRSV infection without adverse inflammatory reaction