New neutron detector based on Micromegas technology for ADS projects

A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described

The Chloroplast Genome of the Green Alga Schizomeris leibleinii (Chlorophyceae) Provides Evidence for Bidirectional DNA Replication from a Single Origin in the Chaetophorales

In the Chlorophyceae, the chloroplast genome is extraordinarily fluid in architecture and displays unique features relative to other groups of green algae. For the Chaetophorales, 1 of the 5 major lineages of the Chlorophyceae, it has been shown that the distinctive architecture of the 223,902-bp genome of Stigeoclonium helveticum is consistent with bidirectional DNA replication from a single origin. Here, we report the 182,759-bp chloroplast genome sequence of Schizomeris leibleinii, a member of the earliest diverging lineage of the Chaetophorales. Like its Stigeoclonium homolog, the Schizomeris genome lacks a large inverted repeat encoding the rRNA operon and displays a striking bias in coding regions that is associated with a bias in base composition along each strand. Our results support the notion that these two chaetophoralean genomes replicate bidirectionally from a putative origin located in the vicinity of the small subunit ribosomal RNA gene. Their shared structural characteristics were most probably inherited from the common ancestor of all chaetophoralean algae. Short dispersed repeats account for most of the 41-kb size variation between the Schizomeris and Stigeoclonium genomes, and there is no indication that homologous recombination between these repeated elements led to the observed gene rearrangements. A comparison of the extent of variation sustained by the Stigeoclonium and Schizomeris chloroplast DNAs (cpDNAs) with that observed for the cpDNAs of the chlamydomonadalean Chlamydomonas and Volvox suggests that gene rearrangements as well as changes in the abundance of intergenic and intron sequences occurred at a slower pace in the Chaetophorales than in the Chlamydomonadales

Deciduous Trees and the Application of Universal DNA Barcodes: A Case Study on the Circumpolar Fraxinus

The utility of DNA barcoding for identifying representative specimens of the circumpolar tree genus Fraxinus (56 species) was investigated. We examined the genetic variability of several loci suggested in chloroplast DNA barcode protocols such as matK, rpoB, rpoC1 and trnH-psbA in a large worldwide sample of Fraxinus species. The chloroplast intergenic spacer rpl32-trnL was further assessed in search for a potentially variable and useful locus. The results of the study suggest that the proposed cpDNA loci, alone or in combination, cannot fully discriminate among species because of the generally low rates of substitution in the chloroplast genome of Fraxinus. The intergenic spacer trnH-psbA was the best performing locus, but genetic distance-based discrimination was moderately successful and only resulted in the separation of the samples at the subgenus level. Use of the BLAST approach was better than the neighbor-joining tree reconstruction method with pairwise Kimura's two-parameter rates of substitution, but allowed for the correct identification of only less than half of the species sampled. Such rates are substantially lower than the success rate required for a standardised barcoding approach. Consequently, the current cpDNA barcodes are inadequate to fully discriminate Fraxinus species. Given that a low rate of substitution is common among the plastid genomes of trees, the use of the plant cpDNA “universal” barcode may not be suitable for the safe identification of tree species below a generic or sectional level. Supplementary barcoding loci of the nuclear genome and alternative solutions are proposed and discussed

Faut-il encore avoir peur de nos déchets ménagers ? Un risque redoutable : la dispersion incontrôlée

International audienceWith real examples in a french department it is seen that household refuse and other similar refuses are not so ordinary that it can be thought. Their scattering dilutes discharges, but often goes with no treatment and then increases health and environment risks. This scattering concerns as much products as refuses which follows from them.Par des exemples concrets sur un département, on voit que les déchets ménagers et assimilés ne sont pas aussi banals qu'on pourrait le penser. Leur dispersion dilue les rejets, mais s'accompagne souvent d'une absence de traitement et accroît alors les risques pour la santé et l'environnement. Cette dispersion concerne autant les produits d'origine que les déchets qui en découlent

Un risque redoutable : la dispersion incontrôlée

International audienceWith real examples in a french department it is seen that household refuse and other similar refuses are not so ordinary that it can be thought. Their scattering dilutes discharges, but often goes with no treatment and then increases health and environment risks. This scattering concerns as much products as refuses which follows from them.Par des exemples concrets sur un département, on voit que les déchets ménagers et assimilés ne sont pas aussi banals qu'on pourrait le penser. Leur dispersion dilue les rejets, mais s'accompagne souvent d'une absence de traitement et accroît alors les risques pour la santé et l'environnement. Cette dispersion concerne autant les produits d'origine que les déchets qui en découlent

Bernheim Rosenthal Gabrielle, Journal (1897-1932)

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My Uncle Benjamin.

Mode of access: Internet

My Uncle Benjamin,

Mode of access: Internet

Belle-Plante and Cornelius,

Mode of access: Internet

My Uncle Benjamin; a humorous, satirical, and philosophical novel,

Mode of access: Internet