A criterion for quadraticity of a representation of the fundamental group of an algebraic variety

13 pagesInternational audienceLet $\Gamma$ be a finitely presented group and $G$ a linear algebraic group over $\mathbb{R}$. A representation $\rho:\Gamma\rightarrow G(\mathbb{R})$ can be seen as an $\mathbb{R}$-point of the representation variety $\mathfrak{R}(\Gamma, G)$. It is known from the work of Goldman and Millson that if $\Gamma$ is the fundamental group of a compact Kähler manifold and $\rho$ has image contained in a compact subgroup then $\rho$ is analytically defined by homogeneous quadratic equations in $\mathfrak{R}(\Gamma, G)$. When $X$ is a smooth complex algebraic variety, we study a certain criterion under which this same conclusion holds

Vulnerability of the agricultural sector to climate change: The development of a pantropical Climate Risk Vulnerability Assessment to inform sub-national decision making

As climate change continues to exert increasing pressure upon the livelihoods and agricultural sector of many developing and developed nations, a need exists to understand and prioritise at the sub national scale which areas and communities are most vulnerable. The purpose of this study is to develop a robust, rigorous and replicable methodology that is flexible to data limitations and spatially prioritizes the vulnerability of agriculture and rural livelihoods to climate change. We have applied the methodology in Vietnam, Uganda and Nicaragua, three contrasting developing countries that are particularly threatened by climate change. We conceptualize vulnerability to climate change following the widely adopted combination of sensitivity, exposure and adaptive capacity. We used Ecocrop and Maxent ecological models under a high emission climate scenario to assess the sensitivity of the main food security and cash crops to climate change. Using a participatory approach, we identified exposure to natural hazards and the main indicators of adaptive capacity, which were modelled and analysed using geographic information systems. We finally combined the components of vulnerability using equal-weighting to produce a crop specific vulnerability index and a final accumulative score. We have mapped the hotspots of climate change vulnerability and identified the underlying driving indicators. For example, in Vietnam we found the Mekong delta to be one of the vulnerable regions due to a decline in the climatic suitability of rice and maize, combined with high exposure to flooding, sea level rise and drought. However, the region is marked by a relatively high adaptive capacity due to developed infrastructure and comparatively high levels of education. The approach and information derived from the study informs public climate change policies and actions, as vulnerability assessments are the bases of any National Adaptation Plans (NAP), National Determined Contributions (NDC) and for accessing climate finance

Olivier Forcade, La Censure en France pendant la Grande Guerre

Comment organiser la censure de la presse, de l’édition et des spectacles en temps de guerre dans une République qui a fait de la loi du 29 juillet 1881, un des piliers de la liberté politique par refus de la législation du Deuxième Empire ? Dans une vie politique française nourrie de réminiscences historiques pour le motif qu’elle prétend réaliser, hic et nunc, le développement d’un processus historique qui conduit inéluctablement vers l’âge positif, la date du 29 juillet renvoie aux ordonna..

Feix (Marc) et Grandhomme (Jean-Noël) dir., Les évêques alsaciens-lorrains pendant la Grande Guerre (1914-1918)

Existe-t-il un livre qui ne dévoile une part de la réalité historique ? Non. Les actes de cette journée d’études qui a tenu ses séances à Strasbourg le 18 novembre 2018 seront utiles pour la publication de documents d’accès difficile comme les lettres de soldats (à partir de la page 637) ou le dossier documentaire composé par Jeanine Siat (p. 707 et sq.) qui a recopié des documents des Archives secrètes du Saint-Siège. Ces textes, au-delà de l’empathie à éprouver à l’endroit des hommes qui on..