Jean-David Zeitoun

  • L'amélioration de la santé humaine est une anomalie à l'échelle de l'évolution.
    Pendant des dizaines de milliers d'années, les humains ne vivaient pas plus de trente ans en moyenne. La grande extension de notre espérance de vie a commencé autour des années 1750 en Occident. Lente mais continue, elle est principalement due à la désinfection et à une meilleure alimentation. C'est ainsi que, en deux siècles, notre longévité a doublé. Depuis 1950, les progrès de la médecine et de la pharmacie ont permis de gagner encore vingt-cinq années de vie.
    Mais, en parallèle, les humains ont fait émerger deux énormes risques, environnemental et comportemental, qui causent les maladies chroniques et rendent possible une rétrogression de la santé humaine. La pandémie de Covid-19 n'est pas le fait du hasard. Elle est une illustration sévère des dysfonctionnements des sociétés humaines et notamment de leur rapport à l'environnement. Le SARS-CoV-2 est un produit naturel, mais son émergence et sa persistance sont des produits humains.
    Le grand récit de la santé humaine.

  • These proceedings comprise of invited and contributed papers presented at the 13th International Conference on X-Ray Lasers (ICXRL 2012) which was held 11-15 June 2012 in Paris, France, in the famous Quartier Latin, inside the historical Center of Cordeliers. This conference is part of a continuing series dedicated to recent developments and applications of x-ray lasers and other coherent x-ray sources with attention to supporting technologies and instrumentation.
    New results in the generation of intense coherent x-rays and progress towards practical devices and their applications are reported in these proceedings, including areas of research in plasma-based x-ray lasers, 4th generation accelerator-based sources and higher harmonic generation.
    Recent achievements related to the increase of the repetition rate up to 100 Hz and shorter wavelength collisional plasma-based soft x-ray lasers down to about 7 nm are presented. Seeding the amplifying plasma with a femtosecond high-order harmonic of infrared laser was foreseen as the required breakthrough to break the picosecond frontier. Numerical simulations based on the Maxwell-Bloch model are presented in these proceedings, transposing the chirped pulse amplification technique to the x-ray domain in order to increase the time over which the femtosecond seed can be amplified.
    These proceedings also include innovative applications of soft x-ray lasers based on techniques and diagnostics relevant to topical domains such as EUV lithography, inertial confinement fusion, or warm dense matter physics.

  • Cities built on unconsolidated sediments consisting of clays, silt, peat, and sand, are particularly susceptible to subsidence.  Such regions are common in delta areas, where rivers empty into the oceans, along flood plains adjacent to rivers, and in coastal marsh lands.  Building cities in such areas aggravates the problem for several reasons:1.  Construction of buildings and streets adds weight to the region causing additional soil deformations.
    2.  Often the regions have to be drained in order to be occupied.  This results in lowering of the water table and leads to hydro-compaction.
    3. Often the groundwater is used as a source of water for both human consumption and industrial use.  4. Levees and dams are often built to prevent or control flooding.Earth fissures caused by ground failure in areas of uneven or differential compaction have damaged buildings, roads and highways, railroads, flood-control structures and sewer lines. As emphasized by Barends , "in order to develop a legal framework to claims and litigation, it is essential that direct and indirect causes of land subsidence effects can be quantified with sufficient accuracy from a technical and scientific point of view." Most existing methods and software applications treat the subsidence problem by analyzing one of the causes.  This is due to the fact that the causes appear at different spatial scales. For example, over-pumping creates large scale subsidence, while building loading creates local subsidence/consolidation only. Then, maximum permissible land subsidence (or consolidation) is a constraint in different management problems such as: groundwater management, planning of town and/or laws on building construction. It is, therefore, necessary to quantify the contribution of each cause to soil subsidence of the ground surface in cities urban area. In this text book, we present an engineering approach based on the Biot system of equations to predict the soil settlement due to subsidence, resulting from different causes. Also we present a case study of The Bangkok Metropolitan Area (BMA).