Duverger, semi-presidentialism and the supposed French archetype

The concept of semi-presidentialism was first operationalised by Maurice Duverger. There are now 17 countries with semi-presidential constitutions in Europe. Within this set of countries France is usually considered to be the archetypal example of semi-presidentialism. This article maps the main institutional and political features of European semi-presidentialism on the basis of Duverger’s original three-fold schema. The most striking feature is the diversity of practice within this set of countries. This means that semi-presidentialism should not be operationalised as a discrete explanatory variable. However, there are ways of systematically capturing the variation within semi-presidentialism to allow cross-national comparisons. This diversity also means that France should not be considered as the archetypal semi-presidential country. At best, France is an archetypal example of a particular type of semi-presidentialism. Overall, Duverger’s main contribution to the study of semi-presidentialism was the original identification of the concept and his implicit insight that there are different types of semi-presidentialism. In the future, the study of semi-presidentialism would benefit from the development of theory-driven comparative work that avoids a reliance on France as the supposed semi-presidential archetype

Kinase control of latent HIV-1 infection: PIM-1 kinase as a major contributor to HIV-1 reactivation

pre-printDespite the clinical relevance of latent HIV-1 infection as a block to HIV-1 eradication, the molecular biology of HIV-1 latency remains incompletely understood. We recently demonstrated the presence of a gatekeeper kinase function that controls latent HIV-1 infection. Using kinase array analysis we here expand on this finding and demonstrate that the kinase activity profile of latently HIV-1 infected T cells is altered relative to uninfected T cells. A ranking of altered kinases generated from these kinome profile data predicted PIM-1 kinase as a key switch involved in HIV-1 latency control. Using genetic and pharmacologic perturbation strategies, we demonstrate that PIM-1 activity is indeed required for HIV-1 reactivation in T cell lines and primary CD4 T cells. The presented results thus confirm that kinases are key contributors to HIV-1 latency control. In addition, through mutational studies we link the inhibitory effect of PIM-1 inhibitor IV (PIMi IV) on HIV-1 reactivation to an AP-1 motif in the CD28 responsive element of the HIV-1 long terminal repeat (LTR). The results expand our conceptual understanding of the dynamic interactions of the host-cell and the latent HIV-1 integration event and position kinome profiling as a research tool to reveal novel molecular mechanisms that can eventually be targeted to therapeutically trigger HIV-1 reactivation

Periodically Spaced CaF2_2 Semi-Insulating Thin Ribbons Growth Study on the Si(100) Surface

The use and the study of semi-insulating layers on metals and semiconductors surfaces have found continuous interest in the past decades. So far, the control of the sizes and growth location of the insulating islands on the substrate is either ill-defined or usually constrained to the use of evaporation masks which size can easily exceed tenth of nanometers. Here, we show that it is possible to grow self-organized periodically spaced thin ribbons of semi-insulating stripes on the bare Si(100) surface. The epitaxial growth of these structures is obtained by the evaporation of CaF$_2$ molecules on the silicon surface with a coverage of 1.2 monolayers. They are investigated via scanning tunneling techniques at low temperature (9K). The obtained ribbons exhibit a surface bandgap of ~3.2 eV as well as a resonant state at the central part of the ribbons at ~2.0 eV below the Fermi level energy. The use of the density functional theory allows suggesting a model structure of the observed ribbons and reproducing the experimental STM topographies. The formation of the thin ribbons is discussed and we point out the influence of the mechanical forces inside and between the structures that may influence their periodicity

Fiabilité des systèmes mécatroniques en utilisant la modélisation et la simulation

Colloque avec actes et comité de lecture. internationale.International audience"En phase de conception d’un système mécatronique, une étude de la fiabilité est généralement précédéed’une analyse qualitative qui consiste à définir, avec précision, les relations entre le système et son environnement, les différentes fonctions techniques réalisées par le système, les interactions fonctionnelles et collatérales entre ses éléments,et les différents modes de défaillance et leurs effets sur le système. Ces analyses qui sont complémentaires, peuvent permettre, si elles sont réalisées d’une manière pertinente, de modéliser et de simuler un système mécatronique afin de calculer sa fiabilité prévisionnelle, grâce par exemple, aux réseaux de Petri ou aux diagrammes de fiabilité. On propose dans cet article d’appliquer ce deux méthodes de modélisation employées en sûreté de fonctionnement sur un système mécatronique « actionneur intelligent » afin d’évaluer sa fiabilité avec ou non la prise en compte des interactions et selon son profil de mission.