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International audience; The coherent emission of exciton polaritons was proposed as a means of lowering the lasing threshold because it does not require the dissociation of excitons to obtain an electron-hole plasma, as in a classical semiconductor laser based on population inversion. In this work we propose a method to prove clearly the polaritonic nature of lasing by combining experimental measurements with a model accounting for the permittivity change as a function of the carrier density. To do so we use angle resolved photoluminescence to observe the lasing at cryogenic temperature from a polariton mode in a zinc oxide waveguide structure, and to monitor the continuous shift of the polaritonic dispersion towards a photonic dispersion as the optical intensity of the pump is increased (up to 20 times the one at threshold). This shift is reproduced thanks to a model taking into account the reduction of the oscillator strength and the renormalization of the band gap due to the screening of the electrostatic interaction between electrons and holes. Furthermore, the measurement of the carrier lifetime at optical intensities in the order of those at which the polariton lasing occurs enables us to estimate the carrier density, confirming that it is lower than the corresponding Mott density for zinc oxide reported in the literature.

International audience

O objecto de análise deste artigo são as dinâmicas e reconfigurações do clientelismo político, um dos traços centrais do funcionamento dos sistemas políticos africanos. As recomposições e adaptações dos sistemas políticos africanos na fase das «transições» para as democracias multipartidárias, em África, face às crises políticas, sociais e económicas e o surgimento subsequente de novos actores sociais nas estruturas de poder (político) africanas são o centro de análise deste texto. O artigo sustenta que a «democracia» e o multipartidarismo não contribuíram para a erradicação ou mitigação das práticas clien­telares. O máximo que se conseguiu, até ao momento, foi a criação de condições para a renegociação destas mesmas relações clientelares.The object of this article is to examine the dynamics and reconfigurations of political clientelism, one of the major characteristics of African political systems. The analysis focuses on the restructuring and adapting of African political systems during the «tran­sitional phase» to multi-party democracies in reaction to the political, social and economic crises and the subsequent emergence of new social actors in the African (political) power structures. The article argues that «democracy» and multipartyism have not contributed to eradicate or mitigate clientelist practices and that most achieved, until now, has been the creation of conditions that favor the renegotiation of clientelist relationships.

O objecto de análise deste artigo são as dinâmicas e reconfigurações do clientelismo político, um dos traços centrais do funcionamento dos sistemas políticos africanos. As recomposições e adaptações dos sistemas políticos africanos na fase das «transições» para as democracias multipartidárias, em África, face às crises políticas, sociais e económicas e o surgimento subsequente de novos actores sociais nas estruturas de poder (político) africanas são o centro de análise deste texto. O artigo sustenta que a «democracia» e o multipartidarismo não contribuíram para a erradicação ou mitigação das práticas clien­telares. O máximo que se conseguiu, até ao momento, foi a criação de condições para a renegociação destas mesmas relações clientelares. The object of this article is to examine the dynamics and reconfigurations of political clientelism, one of the major characteristics of African political systems. The analysis focuses on the restructuring and adapting of African political systems during the «tran­sitional phase» to multi-party democracies in reaction to the political, social and economic crises and the subsequent emergence of new social actors in the African (political) power structures. The article argues that «democracy» and multipartyism have not contributed to eradicate or mitigate clientelist practices and that most achieved, until now, has been the creation of conditions that favor the renegotiation of clientelist relationships.

Écrire sur Jacques Foccart constitue pour le politologue un exercice scientifique redoutable dans la mesure où le personnage, en raison du secret dont il s'entourait, de l'influence et de la puissance qu'on lui prêtait, a pris les dimensions d'un véritable mythe. Mais Jacques Foccart n'est pas qu'un mythe. Il a rempli des fonctions importantes auprès du général de Gaulle pendant vingt-trois ans, et a exercé les fonctions officielles de secrétaire général à la Communauté, puis aux Affaires afr...

Ce travail s'inscrit dans le cadre d'un projet de recherche sur les politiques de santé en Afrique centrale (IRD-CEAN-CIESPAC). Je tiens à remercier les personnels du ministère de la Santé Publique pour leur accueil et leur disponibilité. Plus particulièrement, je tiens à remercier les docteurs Alain Vigouroux et Chevalier pour leur aide à la fois matérielle, intellectuelle et amicale. Ils m'ont introduit au domaine, nouveau pour moi, de la santé publique, mais ils ne sont pas responsables de...

Médard Jean-François. Ces messieurs Afrique.... In: Politique africaine, n°49, 1993. L'Europe et l'Afrique : le maillon manquant. pp. 146-148.

Médard Jean-François. Le changement dans la continuité. La Conférence des chefs d'Etats de France et d'Afrique (Paris, 3-4 novembre 1981) :. In: Politique africaine, n°5, 1982. La France en Afrique. pp. 28-34.

L'agglomération de Bordeaux vit sous le régime de la communauté urbaine qui prévoit un double niveau d'administration tant sur le plan des compétences que sur celui des organes. Cette réforme, qui a été imposée par la loi aux communes de l'agglomération a suscité de vives oppositions en banlieue. Les solutions de compromis relatives à la composition du Conseil de communauté et de son bureau reposent sur un équilibre subtil. Elles ont facilité sa mise en place et assurent les bases de son fonctionnement. Ce fonctionnement obéit à une logique intercommunale et non interpartisane. Le président, le vice-président, et surtout le secrétaire avec son état-major, y jouent un rôle prépondérant., Médard Jean-François. Les structures politico-administratives de l'agglomération de Bordeaux. In: Revue géographique des Pyrénées et du Sud-Ouest, tome 42, fascicule 4, 1971. Bordeaux-Toulouse. pp. 411-430.