Pauvreté et RMI en agriculture

Le Revenu minimum d'insertion (RMI) a été instauré à la fin des années quatre-vingt pour faire face à la montée de la pauvreté due au fort accroissement du chômage. Il vise d'une part à assurer un revenu minimum aux personnes durablement privées d'emploi et d'autre part à aider à leur réinsertion sociale et notamment à leur réintégration dans le marché de l'emploi. En 1992, le législateur a étendu ce dispositif au secteur agricole où les actifs sont dans leur grande majorité des travailleurs non salariés et où les situations de pauvreté ne sont pas imputables à la privation d'emploi, mais à la faiblesse des revenus tirés de l'activité professionnelle. Cependant, seulement environ 1% des exploitants agricoles bénéficient du RMI, proportion qui semble a priori très inférieure à la fréquence des situations de pauvreté au sein de la population agricole. Pour éclairer ce paradoxe, il convenait de faire le point sur l'étendue de la pauvreté dans l'agriculture, caractériser la population des bénéficiaires du RMI agricole, étudier les modalités de la mise en œuvre de ce dispositif et examiner les raisons de sa faible diffusion.

A biomechanical model of the face including muscles for the prediction of deformations during speech production

A 3D biomechanical finite element model of the face is presented. Muscles are represented by piece-wise uniaxial tension cable elements linking the insertion points. Such insertion points are specific entities differing from nodes of the finite element mesh, which makes possible to change either the mesh or the muscle implementation totally independently of each other. Lip/teeth and upper lip/lower lip contacts are also modeled. Simulations of smiling and of an Orbicularis Oris activation are presented and interpreted. The importance of a proper account of contacts and of an accurate anatomical description is show

The integrated forest biorefinery, an example of green engineering

1. Introduction Confronted by a steady decline in the demand for commodity papers, the pulp and paper industry has undertaken intensive R&D efforts to identify and develop new non paper products that could be manufactured from the forest biomass. The components of wood that can be separated and converted into new non paper products are the cellulose, hemicelluloses and lignin. Celluloses and hemicelluloses are polymers of various sugars and lignin is a polymer of phenylpropane units. This paper treats the specific case of lignin and hemicellulose extraction from a Kraft pulping process. Two processes have been investigated for the extraction of lignin from black liquor. One is an enhanced version of precipitation of lignin under low pH conditions achieved by carbonation of Kraft black liquor. The work was focused on the efficiency of the lignin flocculation and filtration steps and on the impact of the black liquor withdrawal on the chemical balance of the Kraft process. The second process focuses on the acidification of the black liquor by electrodialysis with bipolar membrane. This process produces clean lignin and valuable caustic soda. In this case the lignin is easily filtered however partial precipitation of lignin may happen in the eletrodialysis cell. A procedure was developed to avoid the occurrence of counterproductive phenomena. The extraction of hemicelluloses from wood chips and their partitioning into a mixture of C5 and C6 sugars can be accomplished by a two-step hydrolysis. The sugars can then be converted into a large number of derivatives. The case of fermentation into butanol is presented. Innovations were made in the process detoxification and the enhancement of the butanol fermentation. The process developed can be integrated to the Kraft mill from the standpoint of steam and water. The energy intensification of the site eliminates the requirement for fossil fuel thus enhancing the feasibility of the green integrated forest biorefinery. Please click Additional Files below to see the full abstract

Models of the water retention curve for soils with a fractal pore size distribution

The relationship between water content and water potential for a soil is termed its water retention curve. This basic hydraulic property is closely related to the soil pore size distribution, for which it serves as a conventional method of measurement. In this paper a general model of the water retention curve is derived for soil whose pore size distribution is fractal in the sense of the Mandelbrot number-size distribution. This model, which contains two adjustable parameters (the fractal dimension and the upper limiting value of the fractal porosity) is shown to include other fractal approaches to the water retention curve as special cases. Application of the general model to a number of published data sets covering a broad range of soil texture indicated that unique, independent values of the two adjustable parameters may be difficult to obtain by statistical analysis of water retention data for a given soil. Discrimination among different fractal approaches thus will require water retention data of high density and precision. (Résumé d'auteur