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Máster Universitario en Enseñanza del Español como Lengua Extranjera y de Otras Lenguas Moderna

Evaluation de la performance des ouvrages hydrauliques en remblai soumis à la présence de la végétation arborescente : proposition d'une approche modulaire

International audienceLa végétation arborée est souvent présente sur les ouvrages hydrauliques en remblai. Or, le développement racinaire de cette végétation met en péril les ouvrages car il est susceptible de contribuer à un mécanisme d'érosion interne lors de la décomposition des racines ligneuses. Curt (2008) a développé des modèles pour l'évaluation de la performance des barrages en remblai équipés de drains et d'instruments d'auscultation. Ces modèles sont basés sur les systèmes à base de connaissances. Ils comportent trois niveaux hiérarchiques : la performance du composant analysé, la performance des fonctions et les indicateurs d'état. Cependant, ce modèle ne prend que partiellement en compte la présence de végétation arborée. De plus, les petits barrages ne sont pas toujours équipés de drains et d'instruments d'auscultation. Nous avons donc proposé une approche modulaire afin de pouvoir évaluer différents types de barrages. Notre étude s'attache donc d'une part, à identifier les indicateurs d'état spécifiques à la végétation arborescente et d'autre part à adapter et compléter les modèles d'évaluation en place. La démarche a été appliquée sur un groupe de 7 barrages français et italiens et a montré sa pertinence

Flap Endonuclease Disengages Dna2 Helicase/Nuclease from Okazaki Fragment Flaps

Okazaki fragments contain an initiator RNA/DNA primer that must be removed before the fragments are joined. In eukaryotes, the primer region is raised into a flap by the strand displacement activity of DNA polymerase {delta}. The Dna2 helicase/nuclease and then flap endonuclease 1 (FEN1) are proposed to act sequentially in flap removal. Dna2 and FEN1 both employ a tracking mechanism to enter the flap 5' end and move toward the base for cleavage. In the current model, Dna2 must enter first, but FEN1 makes the final cut at the flap base, raising the issue of how FEN1 passes the Dna2. To address this, nuclease-inactive Dna2 was incubated with a DNA flap substrate and found to bind with high affinity. FEN1 was then added, and surprisingly, there was little inhibition of FEN1 cleavage activity. FEN1 was later shown, by gel shift analysis, to remove the wild type Dna2 from the flap. RNA can be cleaved by FEN1 but not by Dna2. Pre-bound wild type Dna2 was shown to bind an RNA flap but not inhibit subsequent FEN1 cleavage. These results indicate that there is a novel interaction between the two proteins in which FEN1 disengages the Dna2 tracking mechanism. This interaction is consistent with the idea that the two proteins have evolved a special ability to cooperate in Okazaki fragment processing

Dna2p Helicase/Nuclease Is a Tracking Protein, Like FEN1, for Flap Cleavage during Okazaki Fragment Maturation

During cellular DNA replication the lagging strand is generated as discontinuous segments called Okazaki fragments. Each contains an initiator RNA primer that is removed prior to joining of the strands. Primer removal in eukaryotes requires displacement of the primer into a flap that is cleaved off by flap endonuclease 1 (FEN1). FEN1 employs a unique tracking mechanism that requires the recognition of the free 5' terminus and then movement to the base of the flap for cleavage. Abnormally long flaps are coated by replication protein A (RPA), inhibiting FEN1 cleavage. A second nuclease, Dna2p, is needed to cleave an RPA-coated flap producing a short RPA-free flap, favored by FEN1. Here we show that Dna2p is also a tracking protein. Annealed primers or conjugated biotin-streptavidin complex block Dna2p entry and movement. Single-stranded binding protein-coated flaps inhibit Dna2p cleavage. Like FEN1, Dna2p can track over substrates with a non-Watson Crick base, such as a biotin, or a missing base within a chain. Unlike FEN1, Dna2p shows evidence of a "threading-like" mechanism that does not support tracking over a branched substrate. We propose that the two nucleases both track, Dna2p first and then FEN1, to remove initiator RNA via long flap intermediates

The Baptist Church in Warren: Rehabilitation and Preservation Report

The Baptist Church in Warren is located in the Warren Waterfront Historic National Register District. Warren also has a Voluntary Historic District. Both the National Register Nomination and the Voluntary Historic District have regulations which pertain to changes to the exterior view shed of the building. Exterior work on this project will need to abide by the State of Rhode Island and the Providence Plantations Rehabilitation Code for existing buildings and structures and the Town of Warren Department of Building and Zoning. Exterior work done on a voluntary basis, according to the Warren Voluntary Historic District guidelines, will qualify for a 20% tax credit. The Baptist Church in Warren does not meet the requirements for the local and state tax credit

The Long Night

From The Sea Birds Are Still Alive (New York: Random House, 1977)

The Writers\u27 Forum: Toni Cade Bambara

Brief statement by Toni Cade Bambara for the Writers\u27 Forum