Origin and evolution of the light nuclides

After a short historical (and highly subjective) introduction to the field, I discuss our current understanding of the origin and evolution of the light nuclides D, He-3, He-4, Li-6, Li-7, Be-9, B-10 and B-11. Despite considerable observational and theoretical progress, important uncertainties still persist for each and every one of those nuclides. The present-day abundance of D in the local interstellar medium is currently uncertain, making it difficult to infer the recent chemical evolution of the solar neighborhood. To account for the observed quasi-constancy of He-3 abundance from the Big Bang to our days, the stellar production of that nuclide must be negligible; however, the scarce observations of its abundance in planetary nebulae seem to contradict this idea. The observed Be and B evolution as primaries suggests that the source composition of cosmic rays has remained quasi-constant since the early days of the Galaxy, a suggestion with far reaching implications for the origin of cosmic rays; however, the main idea proposed to account for that constancy, namely that superbubbles are at the source of cosmic rays, encounters some serious difficulties. The best explanation for the mismatch between primordial Li and the observed "Spite-plateau" in halo stars appears to be depletion of Li in stellar envelopes, by some yet poorly understood mechanism. But this explanation impacts on the level of the recently discovered early ``Li-6 plateau'', which (if confirmed), seriously challenges current ideas of cosmic ray nucleosynthesis.Comment: 18 pages, 9 figs. Invited Review in "Symposium on the Composition of Matter", honoring Johannes Geiss on the occasion of his 80th birthday (Grindelwald, Switzerland, Sept. 2006), to be published in Space Science Series of ISS

Relative frequencies of inherited retinal dystrophies and optic neuropathies in Southern France: assessment of 21-year data management

PURPOSE: Inherited retinal dystrophies (IRDs) and inherited optic neuropathies (IONs) are rare diseases defined by specific clinical and molecular features. The relative prevalence of these conditions was determined in Southern France. METHODS: Patients recruited from a specialized outpatient clinic over a 21-year period underwent extensive clinical investigations and 107 genes were screened by polymerase chain reaction/sequencing. RESULTS: There were 1957 IRD cases (1481 families) distributed in 70% of pigmentary retinopathy cases (56% non-syndromic, 14% syndromic), 20% maculopathies and 7% stationary conditions. Patients with retinitis pigmentosa were the most frequent (47%) followed by Usher syndrome (10.8%). Among non-syndromic pigmentary retinopathy patients, 84% had rod-cone dystrophy, 8% cone-rod dystrophy and 5% Leber congenital amaurosis. Macular dystrophies were encountered in 398 cases (30% had Stargardt disease and 11% had Best disease). There were 184 ION cases (127 families) distributed in 51% with dominant optic neuropathies, 33% with recessive/sporadic forms and 16% with Leber hereditary optic neuropathy. Positive molecular results were obtained in 417/609 families with IRDs (68.5%) and in 27/58 with IONs (46.5%). The sequencing of 5 genes (ABCA4, USH2A, MYO7A, RPGR and PRPH2) provided a positive molecular result in 48% of 417 families with IRDs. Except for autosomal retinitis pigmentosa, in which less than half the families had positive molecular results, about 75% of families with other forms of retinal conditions had a positive molecular diagnosis. CONCLUSIONS: Although gene discovery considerably improved molecular diagnosis in many subgroups of IRDs and IONs, retinitis pigmentosa, accounting for almost half of IRDs, remains only partly molecularly defined

L’utilisation d’une mousse terrestre (Grimmia orbicularis Bruch) comme indicateur de la présence de manganèse 54, de cæsium 137 et de strontium 90

Des mousses terrestres (Grimmia orbicularis Bruch) sont contaminées expérimentalement avec du manganèse 54, du cæsium 137 et du strontium 90. Pour chaque radionucléide, on étudie simultanément la capacité de fixation de la plante à partir de l’eau et du sol. Les auteurs cherchent par ailleurs à déterminer le rôle joué par les variations hygrométriques sur la cinétique et l’intensité de la contamination. — Pour le manganèse 54, le facteur de concentration est de l’ordre de 700. La fixation est importante à partir de l’eau; à partir du sol, elle est liée à la teneur en manganèse échangeable. — Pour le cæsium 137, le facteur de concentration est compris entre 90 et 180. Les échanges ne s’effectuent qu’entre l’eau et la plante. — Pour le strontium 90, le facteur de concentration varie de 100 à 500. Même si l’intensité des échanges est maximale entre l’eau et la plante, une possibilité de contamination secondaire à partir du sol n’en existe pas moins réellement. L’alternance de phases d’assèchement et de réhydratation du milieu influe peu sur le taux de fixation des radionucléides, car les mousses semblent bien les retenir très fortement. Les mousses terrestres, comme les mousses aquatiques, répondent de manière correcte aux exigences du contrôle sanitaire; elles peuvent être choisies comme indicatrices de pollution radioactive

Experimental study and modelling of the transfer of zinc in a low reactive sand column in the presence of acetate.

International audienc

Comparative assessment of agro-environmental performance of vineyard sprayers using a physical full scale model of a vineyard row

International audienceNational policies in Europe aim to reduce use of pesticides. Grapevine receives yearly many sprayings. There is a great variety of sprayers available for vineyards. We can sum up ques-tions addressed to research bodies by the following issues. Is it possible to sort out sprayers and practices according to crop protection and environmental performances? How much is it possible to save on amounts of chemicals sprayed when one uses an efficient sprayer? The present contribution to this research is based on a 4 rows, 10 meters length, physical full scale model of a vineyard. The Evasprayviti model of a vineyard row was designed to repro-duce different foliage volume and densities and to simulate the interaction of the canopy with the flow of plant protection product and air emitted by a mobile sprayer. It comprises a col-lecting device, and a complementary structure on each side of it. The collecting device ena-bles accurate and repeatable sampling of the spray deposits. It is composed of plastic sheets that simulate leaves, attached to vertical aluminium posts. The complementary structure pre-vents perturbative effects on the spray flow on the edges of the collecting device. Evasprayviti can be configured to simulate different growth stages (Codis&al, 2013). The test spray is a mix of a tracer, Tartrazine, and water. A standard pneumatic sprayer, an airblast sprayer and an air-assisted face to face sprayer were tested. The pneumatic sprayer was tested in 3 configurations, for spraying respectively 2, 3 and 4 rows at a time. The face to face sprayer and the airblast sprayer were configured to be used to spray 3 rows and 2 rows, respectively. The amount of product deposited in the canopy and its distribution according to depth and height of leaves was studied for early, intermediate and full growth stage, with respective Leaf Area Index (LAI) values of 0.24, 0.88 and 1.68 ha/ha. The sampling of a cross-section of the collecting device was divided in compartments (3 depths x 3 heights at full growth stage). Deposits on rows close to sprayer and on rows next to sprayer were compared when relevant. The mass of deposits per unit of leaf surface, normalised by amount sprayed per hectare of ground, was measured for each compartment. For precision assessment, this normalised deposit was divided by the reference potential deposit on the target, which is cal-culated for each growth stage according to the hypothesis that all the spray is homogeneous-ly deposited in the compartments. Results showed different deposition profiles, which are discussed. The face to face sprayer exhibited the best efficiency and homogeneity in full and intermediate growth stage, and best efficiency on early stage as well, with homogeneity comparable to the pneumatic sprayer's on this stage. The airblast sprayer used on two rows had a good overall efficiency for early and intermediate stages but a bad homogeneity at all stages

115 PW–850 J compressed beam demonstration using the PETAL facility

International audienceThe Petawatt Aquitaine Laser (PETAL) facility was designed and constructed by the French Commissariat à l'énergie atomique et aux énergies alternatives (CEA) as an additional PW beamline to the Laser MegaJoule (LMJ) facility. PETAL energy is limited to 1kJ at the beginning due to the damage threshold of the final optics. In this paper, we present the commissioning of the PW PETAL beamline. The first kJ shots in the amplifier section with a large spectrum front end, the alignment of the synthetic aperture compression stage and the initial demonstration of the 1.15 PW @ 850 J operations in the compression stage are detailed