Les présents travaux portent sur la prédiction du comportement d’une coque de motomarine lors de l’impact contre un plan d’eau. Ce mémoire présente la démarche suivie afin de prédire les déformations d’une coque. Dans un premier temps, on présente les résultats numériques développés pour ensuite les comparer à nos résultats analytiques et expérimentaux ainsi que d’autres provenant de la littérature. Au niveau des pressions, on semble être en mesure de bien reproduire l’interaction fluide-structure. Lorsque la taille du maillage devient trop grande, les modèles ne permettent plus de reproduire les pressions. Le modèle de motomarine discrétisé avec des éléments trop grossier ne permet pas de reproduire correctement l’interaction fluide-structure. Pour ce qui est des déformations, on remarque évidemment que lorsque l’interaction fluide-structure n’est pas reproduite adéquatement, les niveaux de déformation ne sont pas correctement prédits. D’un point de vue plus général, on constate que la forme de la trace temporelle est de même nature (c’est-à-dire la position des maximums et l’intensité relative) que ce que l’on retrouve expérimentalement. Par contre, on observe une moins bonne corrélation que celles des pressions. Par exemple, pour une erreur typique sur un maximum de pression de l’ordre de 20%, on obtient souvent une erreur plus grande sur les déformations. Dans les deux cas, les prédictions numériques ont tendance à donner des valeurs inférieures aux mesures expérimentales. Une meilleure caractérisation des matériaux est donc recommandée.

International Telemetering Conference Proceedings / October 25-28, 1999 / Riviera Hotel and Convention Center, Las Vegas, Nevada / The coverage characteristics of the GLONASS constellation is analyzed. The almanac data of GLONASS navigation message are used in the computation according to the operation of the satellites. The ground traces of the GLONASS satellites are plotted. And the probability of visible satellite number is calculated under different latitude conditions. The results are analyzed to give descriptions of the GLONASS constellation. And they are compared with those of GPS's. The conclusion is verified that GLONASS constellation provides better coverage at high latitude.

Between 40 % and 50 % of the Earth’s primary production occurs in marine environments, primarily by phytoplankton. The trace metal micronutrients iron, zinc and cobalt are known to exert a significant biological control on phytoplankton productivity by serving as essential active centres in enzymatic processes such as inorganic carbon, nitrogen and phosphorus acquisition. The distributions and biogeochemistries of iron, zinc and cobalt therefore, have the potential to impact upon the global carbon cycle and hence climate. This research involves investigations into the biogeochemical cycling of iron, zinc and cobalt in the Atlantic Ocean. Iron measurements were conducted during October and November 2009 to determine the distribution and biogeochemistry of iron in the upper water column of the Atlantic Ocean along an Atlantic Meridional Transect (AMT-19). In addition, deck board incubation experiments were performed to establish the role of iron in controlling rates of di-nitrogen (N2) fixation in the North Atlantic. The distribution patterns and biogeochemistries of iron, zinc and cobalt in the South Atlantic at 40° S were determined during the UK GEOTRACES Section GA10 cruises of October 2010 and December 2011 to January 2012. Iron distributions in North Atlantic surface waters were primarily controlled by the transport and deposition of atmospheric dust particles. In the North Atlantic, elevated surface dissolved iron concentrations (0.50 - 1.65 nM) were associated with wet and dry deposition of Saharan dust between 4 and 29° N. To the south of 4° N, surface dissolved iron concentrations were markedly reduced (0.14 nM) indicating that high precipitation rates in the Inter-Tropical Convergence Zone (4 - 10° N) formed a barrier to the large-scale transport of Saharan dust particles, thus iron, to the South Atlantic. Here, the low surface dissolved iron concentrations were balanced by a total dissolvable iron flux out of the surface mixed layer (3.2 µmol m-2 y-1) that was comparable to atmospheric input estimates. Nitrogen fixation rates in the North Atlantic were highest (0.3 – 1.1 nmol L-1 d-1) where surface dissolved iron concentrations were elevated (1.02 nM) and decreased with increasing latitude as iron decreased. Hence, iron variability in the North Atlantic was sufficient to influence nitrogen fixation over a large spatial scale. In the South Atlantic Ocean at 40° S, the vertical and horizontal distributions of dissolved zinc and cobalt showed distinct gradients associated with the water masses present. Zinc concentrations ranged from 15 pM in open ocean surface waters to 8 nM in Antarctic Bottom Waters, whilst cobalt ranged from 2 pM to 80 pM in intermediate waters and was scavenged in deeper waters. Growth limiting mixed layer zinc concentrations resulted from the lack of a direct return path for zinc to the South Atlantic pycnocline with Sub-Antarctic Mode Water. Low zinc in this return path was identified by a linear correlation between zinc and soluble reactive phosphorus that showed a kink at ~ 500 m, much deeper than that observed in other oceanographic regimes. A seasonal study in the Southeast Atlantic revealed that the depletion of zinc over spring-summer periods resulted in an increase in the nutritional importance of cobalt and a shift towards phytoplankton with a cellular preference for cobalt over zinc and/or the ability to co-substitute these two trace metals at the molecular level. These key findings demonstrate the physico-chemical and biological influences that interact to control the distributions and biogeochemistries of iron, zinc and cobalt across diverse oceanographic regimes of the Atlantic Ocean, provide the first examination of zinc and cobalt biogeochemistries along the productive 40° S parallel and highlight the need for additional research in this region.

published_or_final_version / Chemistry / Master / Master of Philosophy

No description available.

Early intervention in cancer and other illnesses is highly desired. The evolution of the proteomics field has benefited the possibility of getting to this goal by allowing researchers to look at different biomarkers. However, the high complexity of biological samples and the low levels at which biomarkers are found in these fluids make the analyses even more complicated.Protein microarrays have arisen as alternatives to traditional methods to look at multiple protein levels simultaneously with the benefit of high specificity, low limits of detection and the requirement of small samples. In this work, a significant improvement in net signals obtained with fluorescent detection (using three-dimensional scaffolds based on silica colloidal crystals -SCC-) is presented in contrast to commercially available flat substrates.A novel approach to extract trace proteins in solution and more complex matrices by using sub-micrometer silica particles as support for antibodies in affinity capture experiments is presented. Bovine Serum Albumin, Ephrin-receptor A2, Alpha-fetoprotein, and Prostate Specific Antigen have been used as model proteins. Recoveries of 90% or more are obtained with this method and reusability of the particles was achieved. MALDI-MS detection was successfully performed with the protein extracts which opens up the opportunity of further analysis such as determining post-translational modifications which is relevant when dealing with biomarker candidates.Last we present the use of our substrates as alternatives to conventional targets in mass spectrometry (MS). Traditional Matrix-assisted Laser Desorption Ionization MS (MALDI-MS) of proteins presents the problem of adduct formation with clusters from the matrix used in the process. Those adducts can affect the accurate determination of the molecular weight for a given protein and when could potentially mask slight differences in molecular weight of very similar proteins in mixtures. We present the alternative of using SCC on silicon wafers as a target for MALDI-MS samples. Our peak widths are extremely narrow and approach the one of the isotopic envelops. At the same time, porosity of our material seems to prevent the formation of adducts, which enables the differentiation of proteins with small molecular weight differences like mutants or same proteins from different sources.

Liver glutathione peroxidase activity is affected by changes in selenium (Se) status. To investigate the effect of Se status on GSH-Px protein we prepared antibodies against rat liver GSH-Px and used them in an ELISA. The immunoreactivity of the anti-GSH-Px antibodies against GSH-Px was both tissue and species specific. When rats were depleted of Se, liver GSH-Px activity decreased exponentially to zero with a half-life of 2.8 d. Liver GSH-Px protein also decreased exponentially, but not to zero, with a longer half-life of 5.2 d. Dietary repletion of Se-deficient rats with 0.5 mg Se/kg diet increased GSH-Px protein and activity after 1 d. After 14 d of repletion the levels of GSH-Px protein and activity had plateaued at the levels present in Se-adequate rats. When Se-deficient rats were injected with 15 or 60 ug Se, only rats injected with 60 ug Se and killed 24 h later showed an increase in GSH-Px protein and activity. These results suggest that when Se is limiting, GSH-Px protein and GSH-Px activity are coordinately regulated by the available Se, but in Se-adequacy homeostatic processes control the level of GSH-Px.

The effects of dietary methionine (Met) on the utilization of selenium (Se) from stored tissue Se and dietary selenomethionine (SeMet) for glutathione peroxidase (GSH-Px) synthesis were studied in male rats. Plasma, liver and muscle Se significantly increased when rats were fed 0.5 mg Se/kg diet as SeMet in a Met-deficient diet for 21 d, whereas tissue GSH-Px activities decreased 43-50% during the SeMet supplementation period, suggesting that Se is deposited as SeMet in general body proteins. By calculation, a significant lower percentage of Se was associated with GSH-Px in Met-deficient as compared to Met-supplemented rats. Dietary Met supplementation increased the incorporation of 75Se from 75SeMet into specific rat selenoproteins in addition to liver GSH-Px. Overall, these results suggest that intact SeMet is preferentially incorporated non-specifically into general body proteins in Met-deficient rats, whereas with supplemental Met, more SeMet is degraded and the released Se used for specific selenoprotein synthesis. (Abstract shortened with permission of author.)

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No description available.