Les scénarios énergétiques à l’épreuve du stockage des énergies intermittentes

A large share of wind and solar in the electricity mix increases the part of fatal and intermittent productions which must be compensated by a back up system able to continuously equate supply and demand. The goal of the study is the dimension of this back up system. The analysis relies on information from wind and solar productions observed today in France and transposed to two scenarios considered for 2050: one with 100% renewables, the other with 50% renewables and 50% nuclear. For both cases, we compute the volume of electricity, which should be transferred annually by the back up system from times of productions surplus to those of deficits. In this operation, the back up must deliver a power and possess a capacity of storage, which are also evaluated. Knowing these required performances for the back up system, a review is made of its foreseeable constituents: exchanges with neighboring countries, adjustment of consumption, storages (gravitational, electrochemical and chemical) and, last but not least, adjustment of the supply with controlled, carbon-free, production sources (mostly hydroelectric and nuclear plants). At the end, this gives an insight on the realism of the scenarios, the efforts they require, and the uncertainties in their achievement. Even if our results could be modulated by other hypotheses, their main lesson would remain and cannot be disregarded in the conduct of the energy transition

Les scénarios énergétiques à l’épreuve du stockage des énergies intermittentes

A large share of wind and solar in the electricity mix increases the part of fatal and intermittent productions which must be compensated by a back up system able to continuously equate supply and demand. The goal of the study is the dimension of this back up system. The analysis relies on information from wind and solar productions observed today in France and transposed to two scenarios considered for 2050: one with 100% renewables, the other with 50% renewables and 50% nuclear. For both cases, we compute the volume of electricity, which should be transferred annually by the back up system from times of productions surplus to those of deficits. In this operation, the back up must deliver a power and possess a capacity of storage, which are also evaluated. Knowing these required performances for the back up system, a review is made of its foreseeable constituents: exchanges with neighboring countries, adjustment of consumption, storages (gravitational, electrochemical and chemical) and, last but not least, adjustment of the supply with controlled, carbon-free, production sources (mostly hydroelectric and nuclear plants). At the end, this gives an insight on the realism of the scenarios, the efforts they require, and the uncertainties in their achievement. Even if our results could be modulated by other hypotheses, their main lesson would remain and cannot be disregarded in the conduct of the energy transition

A robust collagen scoring method for human liver fibrosis by second harmonic microscopy.

International audienceSecond Harmonic Generation (SHG) microscopy offers the opportunity to image collagen of type I without staining. We recently showed that a simple scoring method, based on SHG images of histological human liver biopsies, correlates well with the Metavir assessment of fibrosis level (Gailhouste et al., J. Hepatol., 2010). In this article, we present a detailed study of this new scoring method with two different objective lenses. By using measurements of the objectives point spread functions and of the photomultiplier gain, and a simple model of the SHG intensity, we show that our scoring method, applied to human liver biopsies, is robust to the objective's numerical aperture (NA) for low NA, the choice of the reference sample and laser power, and the spatial sampling rate. The simplicity and robustness of our collagen scoring method may open new opportunities in the quantification of collagen content in different organs, which is of main importance in providing diagnostic information and evaluation of therapeutic efficiency

Low autocrine interferon beta production as a gene therapy approach for AIDS: Infusion of interferon beta-engineered lymphocytes in macaques chronically infected with SIVmac251

BACKGROUND: The aim of this study was to evaluate gene therapy for AIDS based on the transduction of circulating lymphocytes with a retroviral vector giving low levels of constitutive macaque interferon β production in macaques chronically infected with a pathogenic isolate of SIVmac251. RESULTS: Two groups of three animals infected for more than one year with a pathogenic primary isolate of SIVmac251 were included in this study. The macaques received three infusions of their own lymphocytes transduced ex vivo with the construct encoding macaque IFN-β (MaIFN-β or with a vector carrying a version of the MaIFN-β gene with a deletion preventing translation of the mRNA. Cellular or plasma viremia increased transiently following injection in most cases, regardless of the retroviral construct used. Transduced cells were detected only transiently after each infusion, among the peripheral blood mononuclear cells of all the animals, with copy numbers of 10 to 1000 per 10(6 )peripheral mononuclear cells. CONCLUSION: Long-term follow-up indicated that the transitory presence of such a small number of cells producing such small amounts of MaIFN-β did not prevent animals from the progressive decrease in CD4(+ )cell count typical of infection with simian immunodeficiency virus. These results reveal potential pitfalls for future developments of gene therapy strategies of HIV infection