Ma petite histoire d'intégration des TIC en pédagogie

Comprend des références bibliographiques et webographique

Validity of the Adiabatic Approximation

We analyze the validity of the adiabatic approximation, and in particular the reliability of what has been called the "standard criterion" for validity of this approximation. Recently, this criterion has been found to be insufficient. We will argue that the criterion is sufficient only when it agrees with the intuitive notion of slowness of evolution of the Hamiltonian. However, it can be insufficient in cases where the Hamiltonian varies rapidly but only by a small amount. We also emphasize the distinction between the adiabatic {\em theorem} and the adiabatic {\em approximation}, two quite different although closely related ideas.Comment: 4 pages, 1 figur

Life cycle studies of the hexose transporter of Plasmodium species and genetic validation of their essentiality

A Plasmodium falciparum hexose transporter (PfHT) has previously been shown to be a facilitative glucose and fructose transporter. Its expression in Xenopus laevis oocytes and the use of a glucose analogue inhibitor permitted chemical validation of PfHT as a novel drug target. Following recent re-annotations of the P. falciparum genome, other putative sugar transporters have been identified. To investigate further if PfHT is the key supplier of hexose to P. falciparum and to extend studies to different stages of Plasmodium spp., we functionally analysed the hexose transporters of both the human parasite P. falciparum and the rodent parasite Plasmodium berghei using gene targeting strategies. We show here the essential function of pfht for the erythrocytic parasite growth as it was not possible to knockout pfht unless the gene was complemented by an episomal construct. Also, we show that parasites are rescued from the toxic effect of a glucose analogue inhibitor when pfht is overexpressed in these transfectants. We found that the rodent malaria parasite orthologue, P. berghei hexose transporter (PbHT) gene, was similarly refractory to knockout attempts. However, using a single cross-over transfection strategy, we generated transgenic P. berghei parasites expressing a PbHT–GFP fusion protein suggesting that locus is amenable for gene targeting. Analysis of pbht-gfp transgenic parasites showed that PbHT is constitutively expressed through all the stages in the mosquito host in addition to asexual stages. These results provide genetic support for prioritizing PfHT as a target for novel antimalarials that can inhibit glucose uptake and kill parasites, as well as unveiling the expression of this hexose transporter in mosquito stages of the parasite, where it is also likely to be critical for survival

Évaluation de quelques sources d’erreur dans un inventaire semi-automatisé de l’utilisation agricole du sol : étude de cas à Sainte-Foy

Un inventaire de l'occupation du sol pour chaque terrain agricole peut être produit par le croisement (automatisé) entre une image satellitaire classifiée et une image des terrains, provenant du cadastre numérisé. Trois sources d'erreur sont examinées. L'erreur planimétrique, créée par la « rasteurisation » des polygones-terrain, Terreur dans les proportions des classes d'occupation du sol due à la résolution spatiale, et l'erreur de la classification elle-même. Les résultats démontrent que chacune de ces erreurs varie en fonction des terrains, donnant des inventaires de qualité inégale. Il est difficile de le corréler avec les dimensions des terrains, et de fixer ainsi des dimensions minimales nécessaires au succès de l'inventaire agricole dans un milieu péri-urbain.An inventory of the land cover per individual agricultural plot can be produced by the cross-tabulation of a classified satellite image and an image of plots provided by the digitized land survey of the region. Three sources of error are examined. The planimetric error, created by the rasterization of the ground polygons, the proportional error in the land cover classes due to the spatial resolution and lastly, the classification error itself. The results show that each of these errors varies in relation to the land parcels which produces inventories of unequal quality. It is difficult to correlate them with the plot dimensions, and thus to set the minimal dimensions required to insure the success of the agricultural inventory in a suburban area