Pour une poignée de ressources. Violences armées et pénurie des rentes en Centrafrique

Cet article discute de la pénurie des rentes d’État comme cause et conséquence des conflits armés, dans le cas de la Centrafrique et dans une perspective de géographie politique. Dans ce pays aux ressources limitées, la maigreur, la raréfaction et l’inégale redistribution des rentes d’État favorisent le recours à la violence comme mode de gouvernement et d’extorsion des ressources. Les conflits ont rendu l’État exsangue, ses ressources étant razziées ou « informalisées » par les groupes armés. L’aide internationale multiforme (humanitaire, au développement, au désarmement) se substitue à l’État en province, le maintien à flot dans la capitale, tout en étant en partie détournée, ne permettant pas de changer en profondeur la pénurie chronique des rentes d’État aggravée par les conflits.This article analyzes the shortage of State rents as a cause and a consequence of armed conflicts, in the case of the Central African Republic and in a perspective of political geography. In this country with limited resources, the increasing scarcity and unequal redistribution of State rents favour the use of violence as a mode of government and a mode of extortion of resources. Armed conflicts force the State into bankruptcy because State resources are plundered by armed groups. International aid (humanitarian, development and disarmament) replaces the State in the provinces and maintains its presence in the capital. International aid does not change the chronic shortage of state rents aggravated by conflict

Multiphoton-Excited Luminescent Lanthanide Bioprobes: Two- and Three-Photon Cross Sections of Dipicolinate Derivatives and Binuclear Helicates

Multiphoton excited luminescent properties of water-soluble EuIII and TbIII complexes with derivatives of dipicolinic acid functionalized with a polyoxyethylene pendant arm and terminal groups, [Eu(LOMe)3]3-, [Eu(LNH2)3]3-, and [Tb(LOH)3]3-, as well as of binuclear helicates with overall composition [Ln2(LCX)3] (X ) 2, 5) are investigated. Characteristic emission from the 5D0 and 5D4 excited levels of EuIII and TbIII, respectively, upon ≈800 nm excitation results from three-photon absorption (3PA) for [Eu(LOMe)3]3-, [Eu(LNH2)3]3-, [Tb(LOH)3]3-, and [Ln2(LC2)3], while luminescence from [Eu2(LC5)3] is induced by two-photon absorption (2PA) owing to its 1PA spectrum extending further into the visible. The 3PA cross sections have been determined and are the first ones reported for lanthanide complexes: (i) those of EuIII and TbIII bimetallic helicates [Ln2(LC2)3] are 20 times larger compared to the corresponding values for tris(dipicolinates); (ii) derivatization of dipicolinic acid for TbIII complexes has almost no influence on the 3PA cross section; however, for EuIII complexes a ∼2 times decrease is observed. The feasibility of [Eu2(LC5)3] as multiphoton luminescence bioprobe is demonstrated by two-photon scanning microscopy imaging experiments on HeLa cells incubated with this bimetallic helicate

Ground-breaking Exoplanet Science with the ANDES spectrograph at the ELT

In the past decade the study of exoplanet atmospheres at high-spectral resolution, via transmission/emission spectroscopy and cross-correlation techniques for atomic/molecular mapping, has become a powerful and consolidated methodology. The current limitation is the signal-to-noise ratio during a planetary transit. This limitation will be overcome by ANDES, an optical and near-infrared high-resolution spectrograph for the ELT. ANDES will be a powerful transformational instrument for exoplanet science. It will enable the study of giant planet atmospheres, allowing not only an exquisite determination of atmospheric composition, but also the study of isotopic compositions, dynamics and weather patterns, mapping the planetary atmospheres and probing atmospheric formation and evolution models. The unprecedented angular resolution of ANDES, will also allow us to explore the initial conditions in which planets form in proto-planetary disks. The main science case of ANDES, however, is the study of small, rocky exoplanet atmospheres, including the potential for biomarker detections, and the ability to reach this science case is driving its instrumental design. Here we discuss our simulations and the observing strategies to achieve this specific science goal. Since ANDES will be operational at the same time as NASA's JWST and ESA's ARIEL missions, it will provide enormous synergies in the characterization of planetary atmospheres at high and low spectral resolution. Moreover, ANDES will be able to probe for the first time the atmospheres of several giant and small planets in reflected light. In particular, we show how ANDES will be able to unlock the reflected light atmospheric signal of a golden sample of nearby non-transiting habitable zone earth-sized planets within a few tenths of nights, a scientific objective that no other currently approved astronomical facility will be able to reach.Comment: 66 pages (103 with references) 20 figures. Submitted to Experimental Astronom

Représentations médiatiques des migrants forcés d’Afrique centrale et rapports de force géopolitiques

International audienc

Les ressources de l’Etat au crible des violences en Centrafrique

National audienc

La guerre en Centrafrique à l'ombre du Tchad. Une escalade conflictuelle régionale ?

International audienceAu cœur du continent africain, la guerre civile en Centrafrique n’en finit plus. Elle s’est régionalisée par l’intervention d’acteurs armés venus des pays voisins, mais sans que les combats s’étendent au-delà des frontières. Cette guerre, dans laquelle des bandits, des rebelles et des mercenaires font le coup de feu pour le contrôle du pouvoir et des ressources, se déroule à l’ombre du Tchad. Ponctué de cartes et de témoignages, cet ouvrage explore l’escalade conflictuelle régionale et la modification par les insécurités des échanges régionaux, du peuplement et des limites interreligieuses

Mobilités sous contraintes et recompositions des échanges vivriers au nord-ouest de la Centrafrique

International audienc

Afrique subsaharienne. Régionalisation de la sécurité et de l’insécurité

International audienc

Les agriculteurs de la région de Paoua face aux conflits armés (Centrafrique)

Rapport d'expertise. Première urgence, Université Paris 1 Panthéon-Sorbonne

Tchad 2011-2012. Stabilité dans un environnement régional conflictuel

International audienc