Au coeur du web participatif: AJAX

L’objectif principal de ce mémoire fut l'étude des différentes technologies composant Ajax et la réalisation d'un prototype d'application illustrant leur mise en œuvre. Pour ce faire nous avons commencé par exposer ce qu’est le Web et son évolution, tout en faisant le lien entre l’apparition d’applications Web se rapprochant de celles dites de bureau et l’apparition d’Ajax. Par la suite, nous avons expliqué le principe de fonctionnement d’Ajax et ce qu’il apporte, puis détaillé les différentes technologies qui le composent. Nous avons présenté la syntaxe et le fonctionnement de ces différents langages, qui peuvent d'ailleurs tous fonctionner de manière indépendants les unes des autres. Enfin, après avoir détaillé le prototype d'application et son fonctionnement, nous avons parlé, avec les frameworks, des différents moyens mis à disposition d’un développeur pour construire une application Ajax, de ses points forts et de ses points faibles ainsi que des autres méthodes permettant d’obtenir des résultats similaires à une application Ajax

Chemical and enzymatic routes to dihydroxyacetone phosphate

Stereoselective carbon-carbon bond formation with aldolases has become an indispensable tool in preparative synthetic chemistry. In particular, the dihydroxyacetone phosphate (DHAP)-dependent aldolases are attractive because four different types are available that allow access to a complete set of diastereomers of vicinal diols from achiral aldehyde acceptors and the DHAP donor substrate. While the substrate specificity for the acceptor is rather relaxed, these enzymes show only very limited tolerance for substituting the donor. Therefore, access to DHAP is instrumental for the preparative exploitation of these enzymes, and several routes for its synthesis have become available. DHAP is unstable, so chemical synthetic routes have concentrated on producing a storable precursor that can easily be converted to DHAP immediately before its use. Enzymatic routes have concentrated on integrating the DHAP formation with upstream or downstream catalytic steps, leading to multi-enzyme arrangements with up to seven enzymes operating simultaneously. While the various chemical routes suffer from either low yields, complicated work-up, or toxic reagents or catalysts, the enzymatic routes suffer from complex product mixtures and the need to assemble multiple enzymes into one reaction scheme. Both types of routes will require further improvement to serve as a basis for a scalable route to DHA

Study of Vk centers in CsI crystals

Vk centers were observed in CsI doped with Na+ and Tl+ after x-ray irradiation at liquid He temperature by using optical and EPR techniques. They are oriented along [100] directions. By studying thermoluminescence, 2 types of thermal migration were found, one due to linear displacement of the centers along the cubic axis and the other due to 90° rotations. They correspond to 2 glow peaks at 60 and 90°K, respectively

Radio and thermoluminescence studies in CsI doped with F centers

Radioluminescence, thermoluminescence, and u.v. excitation measurements in CsI additively colored crystals showed a new luminescent component at 2.5 eV. This is attributed to the radiative recombination of Vk centers with F centers. Another new component at 2.72 eV was observed only under uv excitation of 5.14 eV. This is related to the radiative recombination of localized excitons at F+ center sites (α band)

Modulation frequency-shift technique for dispersion measurements in optical fibers

An improved technique for chromatic dispersion measurements in single-mode fibers using phase-shift measurements is presented. The conventional experimental setup using a modulated light-emitting diode filtered by a monochromator as a light source, a fast receiver, and a vector voltmeter for the phase measurements suffers from inherent drawbacks such as strong phase fluctuations due to poor SNR and RF interference providing biased measurements. The improved method eliminates these drawbacks with optical signal processing by shifting the modulation frequency down to the kilohertz range and maintaining the phase resolution due to high-frequency modulation. The advantages inherent in low-frequency detection and signal processing, such as stability, low noise, and strong filtering capability, and the resolution achieved by using a high modulation frequency result in reliable and accurate group delay measurements, giving a measured standard deviation of <0.5 nm for the zero chromatic dispersion wavelength

Novel method for high-throughput colony PCR screening in nanoliter-reactors

We introduce a technology for the rapid identification and sequencing of conserved DNA elements employing a novel suspension array based on nanoliter (nl)-reactors made from alginate. The reactors have a volume of 35 nl and serve as reaction compartments during monoseptic growth of microbial library clones, colony lysis, thermocycling and screening for sequence motifs via semi-quantitative fluorescence analyses. nl-Reactors were kept in suspension during all high-throughput steps which allowed performing the protocol in a highly space-effective fashion and at negligible expenses of consumables and reagents. As a first application, 11 high-quality microsatellites for polymorphism studies in cassava were isolated and sequenced out of a library of 20 000 clones in 2 days. The technology is widely scalable and we envision that throughputs for nl-reactor based screenings can be increased up to 100 000 and more samples per day thereby efficiently complementing protocols based on established deep-sequencing technologie