Supermanifolds - Application to Supersymmetry

Parity is ubiquitous, but not always identified as a simplifying tool for computations. Using parity, having in mind the example of the bosonic/fermionic Fock space, and the framework of Z_2-graded (super) algebra, we clarify relationships between the different definitions of supermanifolds proposed by various people. In addition, we work with four complexes allowing an invariant definition of divergence: - an ascending complex of forms, and a descending complex of densities on real variables - an ascending complex of forms, and descending complex of densities on Grass mann variables. This study is a step towards an invariant definition of integrals of superfunctions defined on supermanifolds leading to an extension to infinite dimensions. An application is given to a construction of supersymmetric Fock spaces.Comment: to appear in the "Michael Marinov Memorial Volume

Simulation-based medical education training improves short and long-term competency in, and knowledge of central venous catheter insertion: A before and after intervention study

Multimodal educational interventions have been shown to improve short-term competency in, and knowledge of central venous catheter (CVC) insertion

Multiproxy analyses of Lake Allos reveal synchronicity and divergence in geosystem dynamics during the Lateglacial/Holocene in the Alps

International audiencePalaeoenvironmental reconstructions of ecosystem responses to external forcing are generally limited by the difficulty of understanding the geosystem as a whole, because of the complex interactions between ecological compartments. Therefore, identifying which geosystem compartments or proxies co-vary is a prerequisite in unravelling the propagation of disturbances (e.g. climatic or anthropogenic) from one compartment to another. A multiproxy study of a continuous 13,500-year sedimentary profile cored in Lake Allos (European Alps, 2200 m a.s.l) was carried out on the basis of high-resolution sedimentological, geochemical, and botanical analyses, as well as determination of aquatic biotic proxies (diatoms, ostracods). These multiproxy datasets are rare at these high altitudes. Major changes occurred in the course of the palaeoenvironmental history of this alpine watershed at 12,000, 8600, 7200 and 3000 cal. BP. During the Holocene, two main transitions were recorded in all the ecological compartments (8600 and 3000 cal. BP), but the period 4500-3000 cal. BP stands out because of major changes that concerned only the lacustrine ecosystem. The frequent switches in lake level might correspond to the 4.2 ka climatic event. Proximity of this alpine lake to climatically-sensitive thresholds (ice-cover, thermal stratification, hydrological balance) may have amplified climatic signals in the lake ecosystem. This study illustrates the difficulties inherent to the use of common intra-Holocene stratigraphical limits, given that ecological compartments are likely to have different responses to forcing factors depending on the characteristics of the watershed and its capacity to accommodate disturbances. (C) 2018 Elsevier Ltd. All rights reserved

The overlooked human influence in historic and prehistoric floods in the European Alps

International audienceUnderstanding the role of climate and humans in generating mountain slope instability is crucial because such instability influences downstream fluvial activity and is a major threat to societies. Here, we use the sedimentary archive of Lake Allos (southeastern France), a mountain lake in the European Alps, to characterize mountain flood deposits and vegetation dynamics over the past 7000 yr. Our results support the interpretation of a critical threshold in catchment sensitivity to erosion at 1700 calibrated (cal.) yr B.P. (A.D. 250) probably resulting from long-term, uninterrupted impacts of human activity. The frequency and severity of floods increased dramatically after this date. These results demonstrate that underestimation of human impacts over the Holocene may pose a challenge to a clear understanding of past climate changes because paleoflood records are highly likely to have been affected by geomorphic thresholds. Natural reforestation since the end of the 19th century does not appear to be sufficient to induce a flood regime comparable to that which occurred prior to 1700 cal. yr B.P. This poses the question as to whether forest restoration in high-altitude environments is liable to foster a return to a low-erosion regime over the next decades, or whether the overall severity of soil degradation has been such as to preclude a return to previous conditions

The overlooked human influence in the Late Holocene great acceleration of floods in the European Alps

International audienc

Angiotensin II activates the Smad pathway during epithelial mesenchymal transdifferentiation

Epithelial to mesenchymal transdifferentiation is a novel mechanism that promotes renal fibrosis and here we investigated whether known causes of renal fibrosis (angiotensin II and transforming growth factor β, TGFβ) act through this pathway. We infused angiotensin II into rats for 1 day and found that it activated the Smad pathway which persisted for up to 2 weeks in chronically infused rats. Renal TGF-β mRNA expression was increased at 3 days and its protein at 2 weeks suggesting Smad pathway activation occurred earlier than TGF-β upregulation. In cultured human tubuloepithelial cells, angiotensin II caused a rapid activation of Smad signaling independent of TGF-β however, Smad-dependent transcription after 1 day was TGF-β mediated. Two weeks of angiotensin II infusion activated genes associated with epithelial mesenchymal transdifferentiation. Stimulation with angiotensin II for 3 days caused transdifferentiation of the cultured epithelial cells by TGF-β-mediated processes; however, early changes were independent of endogenous TGF-β. Smad7 overexpression, which blocks Smad2/3 activation, diminished angiotensin II-induced epithelial mesenchymal transdifferentiation. Our results show that angiotensin II activates the Smad signaling system by TGF-β-independent processes, in vivo and in vitro, causing renal fibrosis