Saint-Ellier-des-Bois : Le Plessis

Bilan scientifique DRAC Basse-Normandie1 p

The role of maternal antibodies in the emergence of severe disease as a result of fragmentation

Population fragmentation is a major problem for the conservation of mammalian species. Since the spread of an infectious disease is related to the intensity of contacts between individuals, fragmentation destabilizes the way the parasites circulate in their host population. Recently, Zinkernagel has proposed that a reduction in the frequency of infections by a parasite could lead to the emergence of severe forms of the disease, previously avoided because the disease was contracted early in life and attenuated by maternal antibodies. However, it is still unclear whether this change in disease expression increases the global mortality it induces because the disease becomes more severe and also less frequent. Here, we use a mathematical model to link population fragmentation with the hypothesis of Zinkernagel. Firstly, we show that there is a change in the severity of the disease during the fragmentation process, especially at a local scale, suggesting that host population fragmentation could be a widespread mechanism of disease emergence. Secondly, we show that the emergence of the severe form of the disease can lead to a significant increase in its induced mortality. Finally, we determine the types of interactions for which the fragmentation of the host population could be the most dangerous

La forêt sur le devant de la scène : une ressource naturelle témoin de notre temps ?

La RGA présente un numéro consacré à la forêt, une ressource territoriale ancienne qui revient au premier plan ; cette forêt aux intérêts multiples et croissants a été « mise en scène » dans des travaux récents. Aujourd’hui les enjeux liés aux besoins énergétiques futurs, l’impact du changement climatique et la conservation de la biodiversité remettent la forêt sur le devant de la scène mondiale. Ainsi 2011 a été décrétée année internationale des forêts par les Nations Unies. A l’échelle locale, un regain d’intérêt est également perceptible depuis plusieurs années ; en France les acteurs publics et privés se mobilisent, des dispositifs pour mieux gérer la forêt se mettent en place (Chartes forestières, Plan d’Approvisionnement Territoriaux, Schémas de desserte, ...). Les territoires alpins sont de ce point de vue des espaces particuliers du fait de la topographie, de l’altitude et du climat, qui impliquent des moyens de gestion adaptés. La forêt est ainsi le témoin de notre temps, de l’évolution du climat, des changements énergétiques de nos sociétés, elle structure la dynamique des paysages, elle est aussi l’espace récréatif de nos populations aujourd’hui majoritairement urbaines. This special issue of the Journal of Alpine Research focuses on the forest, a long-standing natural resource that is back in the spotlight. The forest’s multiple and increasingly important roles have been the focus of a number of studies in recent years. Today, issues relating to future energy needs, the impact of climate change, and the conservation of biodiversity, have refocused interest on forests at the world scale. Thus the United Nations declared 2011 the International Year of Forests. At the local scale, there have also been clear signs of change in recent years: in France, both private and public stakeholders are taking action, with measures being introduced to improve forest management (Forest charters, Plans d’Approvisionnement Territoriaux (government initiatives to promote the development of wood energy supplies), and Schémas de desserte (forest access programmes). In this respect, the French Alpine areas have a special place on account of their topography, altitude and climate, characteristics that call for suitably adapted management methods. The forest is thus a mirror on our time on earth, on climate change, and on energy changes within our societies. It also structures the dynamics of our landscapes and provides a recreational space for today’s largely urban populations

100 W-level peak power laser system tunable in the LWIR applied to detection of persistent chemical agents

Through the European Defence Agency, the Joint Investment Programme on CBRN protection funded the project AMURFOCAL to address detection at stand-off distances with amplified quantum cascade laser technology in the longwave infrared spectral range, where chemical agents have specific absorptions features. An instrument was developed based on infrared backscattering spectroscopy. We realized a pulsed laser system with a fast tunability from 8 to 10 μm using an external-cavity quantum cascade laser (EC-QCL) and optical parametric amplification (OPA). The EC-QCL is tunable from 8 to 10 μm and delivers output peak powers up to 500 mW. The peak power is amplified with high gain in an orientation-patterned gallium arsenide (OP-GaAs) nonlinear crystal. We developed a pulsed fiber laser acousto-optically tunable from 1880 to 1980 nm with output peak powers up to 7 kW as pump source to realize an efficient quasi-phase matched OPA without any mechanical or thermal action onto the nonlinear crystal. Mixing the EC-QCL and the pump beams within the OP-GaAs crystal and tuning the pump wavelength enables parametric amplification of the EC-QCL from 8 to 10 μm leading to up to 120 W peak power. The output is transmitted to a target at a distance of 10 – 20 m. A receiver based on a broadband infrared detector comprises a few detector elements. A 3D data cube is registered by wavelength tuning the laser emission while recording a synchronized signal received from the target. The presentation will describe the AMURFOCAL instrument, its functional units and its principles of operation

L'état des citoyennetés

Dans nos sociétés contemporaines, sans cesse bouleversées par les restructurations économiques et les recompositions sociales, les institutions étatiques doivent faire face à la difficulté d'assurer l'inclusion sociale et la participation à la vie collective des citoyens. En Europe comme dans les Amériques, nous assistons à des mutations importantes dans les régimes de citoyenneté et à des changements de formes de citoyenneté. Cet ouvrage examine en détail ces transformations, à partir de perspectives multiples qui, non seulement croisent les optiques européennes et canadiennes, mais mobilisent plusieurs disciplines, que ce soit la science politique, la sociologie, le droit ou la philosophie

First results of a QCL-OPA based standoff system, for detecting hazardous substances in the IR-fingerprint domain

Within the framework of the first European Defence Agency (EDA) call for protection against chemical, biological, radiological and nuclear threats (CBRN Protection) we established a project on active multispectral reflection fingerprinting of persistent chemical agents (AMURFOCAL). A first paper on the project AMURFOCAL has been issued last year on the SPIE conference in Warsaw, Poland. This follow up paper will be accompanied by an additional paper that deals specifically with the aspect of the 100 W-level peak power laser system tunable in the LWIR. In order to close a capability gap and to achieve detection at stand-off distances our consortium built a high peak power pulsed laser system with fast tunability from 8 to 10 μm using an external-cavity quantum cascade laser and optical parametric amplification. This system had to be tested against different substances on various surfaces with different angles of inclination to evaluate the ability for an active stand-off technology with an eye-safe laser system to detect small amounts of hazardous substances and residues. The scattered light from the background surface interferes with the signal originating from the persistent chemicals. To account for this additional difficulty new software based on neutral networks was developed for evaluation. The paper describes the basic setup of the instrument and the experiments as well as some first results for this technology

Temporal trajectories of artificial radiocaesium 137Cs in French rivers over the nuclear era reconstructed from sediment cores

(IF 3.8;Q1)International audience137Cs is a long-lived man-made radionuclide introduced in the environment worldwide at the earlybeginning of the nuclear Era during atmospheric nuclear testing’s followed by the civil use of nuclearenergy. Atmospheric fallout deposition of this major artificial radionuclide was reconstructed atthe scale of French large river basins since 1945, and trajectories in French nuclearized rivers wereestablished using sediment coring. Our results show that 137Cs contents in sediments of the studiedrivers display a large spatial and temporal variability in response to the various anthropogenicpressures exerted on their catchment. The Loire, Rhone, and Rhine rivers were the most affected byatmospheric fallout from the global deposition from nuclear tests. Rhine and Rhone also receivedsignificant fallout from the Chernobyl accident in 1986 and recorded significant 137Cs concentrations intheir sediments over the 1970–1985 period due to the regulatory releases from the nuclear industries.The Meuse River was notably impacted in the early 1970s by industrial releases. In contrast, theSeine River display the lowest 137Cs concentrations regardless of the period. All the rivers respondedsimilarly over time to atmospheric fallout on their catchment, underlying a rather homogeneousresilience capacity of these river systems to this source of contamination