<p>Two species of Chrysaora are described from the northern Benguela ecosystem: C. fulgida and C. africana. These species can be diagnosed by a combination of morphological features including lappet and tentacle number, shape of lappets, colouration patterns (alive), shape of the proximal portion of radial septa, gastrovascular pouch shape, point of attachment of gonads and the presence or absence of small raised nematocyst warts on the exumbrellar surface. Objective, quantitative statistical analyses coupled with molecular sequence data support the qualitative morphological dissimilarity observed, as these analyses unambiguously diagnose C. fulgida and C. africana as two distinct species. There is a strong superficial resemblance between the C. fulgida material described here and the preserved specimens of C. hysoscella examined at the Natural History Museum, London. Thorough investigation does however allow the separation of these two species. Morphological features found to be dissimilar were the proximal portion of the manubrium, gastrovascular pouch shape and the presence or absence of sperm sacs. Objective, quantitative statistical analyses support these findings. Nuclear sequence variation suggests considerable divergence between the two species but additional molecular work is needed.</p>

Le pont du Larivot, situé à l’embouchure de la rivière Cayenne et de l’océan Atlantique, est une artère routière indispensable au département amazonien de GuyaneFrançaise. Construit en acier au carbone, il a été fermé en 2009 pour cause de rupture d’une pile par corrosion. La corrosion influencée par les micro-organismes (CIM) estun processus naturel largement étudié dans des milieux tempérés soumis aux marées. L’objectif du travail réalisé ici est d’identifier ses marqueurs dans le cas d’un ouvraged’art en milieu amazonien.Des expériences sur site ont été réalisées sur 30 jours, avec un suivi des phénomènes de corrosion par analyses chimiques, électrochimiques, de surface, et biologiques surdifférents niveaux de marée. Elles montrent que le niveau basse mer (correspondant au niveau du fleuve lorsque la mer est au plus bas) présente les vitesses de corrosionles plus importantes (environ 0, 8 mm.an−1). Ces vitesses, une résistance à la corrosion faible, des micro-organismes fortement présents avec une forte concentration enéléments nutritifs (et particulièrement les nitrates) sont les marqueurs d’un phénomène d’ALWC (accelarated low water corrosion). Des essais effectués en conditions stérilesont confirmés la présence de CIM dans le milieu étudié.Une attention particulière a été portée sur le niveau basse mer avec une étude dynamique de la corrosion sur 50 jours. Ainsi, il a été montré que les phénomènes de surfacesont constants (dépôts de même épaisseur, diffusions de Warbrug identiques), mais avec des vitesses déterminées par courbes de polarisation augmentant linéairement (d’équation vcorr = 0, 004t + 0, 091). La présence dès 10 jours d’oxydes et d’hydroxydes de fer et, dès 30 jours, d’oxydes de manganèse et de sulfure de fer a également été mise en évidence.L’étude du bioflim corrosif montre une modification de la composition bactérienne au cours du temps avec un changement des β- vers les α-protéobactéries. Contrairement aux attentes, les procaryotes sulfato-réducteurs PSR (principalement des δ-protéobacteries) sont pratiquement absents du consortium corrosif. En revanche, des sulfato-oxydateurs sont prépondérants, et particulièrement Rheineimera aquamaris, dont le potentiel corrosif a été prouvé pour la première fois en culture pure.Ainsi, la présence de bactéries aérobies (les sulfato-oxydatrices), l’absence de bactéries anaérobies (PSR) et l’augmentation constante des vitesses montrent qu’après 50 jours le processus de corrosion se situe encore dans une des deux premières phases du modèle de Melcher. Pour compléter cette première étude dans un estuaire amazonien, des expériences à plus long terme doivent donc être réalisées en portant une attention sur la zone de marnage. / The Larivot Bridge, located at the mouth of the Cayenne River and the Atlantic Ocean, is a vital road artery of the Amazonian department of French Guiana. Built incarbon steel, it was closed in 2009 for breach of a pile due to corrosion. Corrosion influenced by microorganisms (MIC) is a natural process widely studied in temperatetidal environments. The objective of the work here is to identify markers in the case of a structure in the Amazonian environment.Experiments were carried out in situ for 30 days, with a follow-up of corrosion by chemical, electrochemical and biological analyses at the low water level. They showthat the low water level (corresponding to the level of the river when the tide is at its lowest) display the faster corrosion (about 0.8 mm.an-1). These rate, the low corrosionresistance, the high microorganisms presence with a high concentration of nutrients (especially the nitrate) are markers of a phenomenon of ALWC (accelarated low watercorrosion). Tests performed under sterile conditions have confirmed the presence of MIC in the medium studied.Particular attention was paid to the low water level with a dynamic study of corrosion on 50 days. Thus, it has been shown that surface phenomena are constant (samethickness of deposit, Warbrug diffusions identical), but with rates determined by polarization curves increasing linearly (equation of vcorr = 0.004t + 0.091). The presence at10 days of iron oxides and hydroxides and from 30 days, oxides of manganese and iron sulfide was also highlighted.The study of the corrosive bioflim shows a change in the bacterial composition over time with a change of β- to α-protéobactéries. Contrary to expectation, the sulfatereducingprokaryotes SRP (mostly δ-protéobacteries) are practically absent in the corrosive consortium. Instead, sulfate-oxidiser are paramount, especially Rheineimera Aquamaris,the corrosive potential has been proven for the first time in pure culture.Thus, the presence of aerobic bacteria (sulfate-oxydatrices), the lack of anaerobic bacteria (SRP) and the constant increase in speeds show that after 50 days the corrosionprocess is still located in one of the first two phases Melcher model. To complete this first study in the Amazon estuary, in the longer term experiments must be performedpaying attention to the tidal zone.

Magister Scientiae (Biodiversity and Conservation Biology) / Two species of Chrysaora are described from the northern Benguela ecosystem: C. fulgida and C. africana. These species can be diagnosed by a combination of morphological features including lappet and tentacle number, shape of lappets, colouration patterns (alive), shape of the proximal portion of radial septa, gastrovascular pouch shape, point of attachment of gonads and the presence or absence of small raised nematocyst warts on the exumbrellar surface. Objective, quantitative statistical analyses coupled with molecular sequence data support the qualitative morphological dissimilarity observed, as these analyses unambiguously diagnose C. fulgida and C. africana as two distinct species. There is a strong superficial resemblance between the C. fulgida material described here and the preserved specimens of C. hysoscella examined at the Natural History Museum, London. Thorough investigation does however allow the separation of these two species. Morphological features found to be dissimilar were the proximal portion of the manubrium, gastrovascular pouch shape and the presence or absence of sperm sacs. Objective, quantitative statistical analyses support these findings. Nuclear sequence variation suggests considerable divergence between the two species but additional molecular work is needed. / South Africa

This work describes the realization of economic and analytical modules of information system of a learning center. It handles about the development and perspectives of its further development. The main part of it is dedicated to the development of system architecture, specification, creation of models and diagrams. An other part handles about the implementation, usage of processing and programming methods and techniques. Highly stressed are analyses and optimalization of processes. The realization of important processes is described in details. A part of the work describes analyses and evaluation of data gained from the IS. Also stressed is the application of modules and its efficiency. Mentioned are advantages and risks brought by this system.

>Magister Scientiae - MSc / Two species of Chrysaora are described from the northern Benguela ecosystem: C. fulgida and C. africana. These species can be diagnosed by a combination of morphological features including lappet and tentacle number, shape oflappets, colouration patterns (alive), shape of the proximal portion of radial septa, gastrovascular pouch shape, point of attachment of gonads and the presence or absence of small raised nematocyst warts on the exumbrellar surface. Objective, quantitative statistical analyses coupled with molecular sequence data support the qualitative morphological dissimilarity observed, as these analyses unambiguously diagnose C. fulgida and C. africana as two distinct species. There is a strong superficial resemblance between the C. fulgida material described here and the preserved specimens of C. hysoscella examined at the Natural History Museum, London. Thorough investigation does however allow the separation of these two species. morphological features found to be dissimilar were the proximal portion of the manubrium, gastrovascular pouch shape and the presence or absence of sperm sacs. Objective, quantitative statistical analyses support these findings. Nuclear sequence variation suggests considerable divergence between the two species but additional molecular work is needed.

No description available.

In this thesis, I have sought to address these issues by developing a toolbox called “Quantitative Tract Integrity Profiles (Q-TIPs)” that: is purely MATLAB-based (making it compatible with most operating systems), has a flexible and user-friendly interface, and will be distributed as a standalone toolbox for the popular Statistical Parametric Mapping (SPM) software package. This toolbox extracts the orientation of any ROI mask by calculating the medial axis using Voronoi and Delaunay algorithms, and then cross-sectional segments along the extracted medial axis are used to create profiles based on any quantitative white matter magnetic resonance imaging metric (e.g., diffusion tensor imaging, myelin water imaging, magnetization transfer imaging, etc.). As a result, this toolbox will enable future neuroimaging studies to more easily and flexibly quantify white matter imaging signals along individual tracts as a function of neural development, healthy aging, traumatic brain injury, or neurodegenerative disease. / February 2017

Les atteintes hépatiques, asymptomatiques pour la plupart d’entre elles et pouvant évoluer vers des complications sévères telles que le carcinome hépatocellulaire (CHC) sont responsables de plus de 15 000 décès par an en France. Le manque de marqueurs cliniques et biologiques fiables pour déterminer le degré de sévérité de l’hépatopathie ainsi que pour reconnaître les stades précoces du CHC constitue actuellement un obstacle majeur à une prise en charge optimale de la maladie. Grâce aux approches de type métabolomique et aux techniques analytiques telles que la résonance magnétique nucléaire, il est désormais possible d’obtenir une véritable cartographie des métabolites d’un individu. L’objectif de ce travail a été d’explorer, par une approche RMN métabolomique, les changements métaboliques dans le foie et dans le sérum causés par différentes pathologies hépatiques afin de proposer de nouvelles pistes dans l’amélioration du diagnostic et de la prise en charge de ces maladies. Une attention particulière a également été donnée à l’étude de la validité des paramètres de qualité des modèles de discrimination réalisés lors des analyses statistiques des données multivariées. / Most liver diseases nowadays remain symptomless and tend to lead to hepatocellular carcinoma responsible for more than 15.000 patient deaths per year in France. Liver diseases are therefore a major concern for public health.Clinicians lack of non-invasive biomarkers allowing them to enhance identification of liver diseases stages in order to efficiently target the first HCC signs and accordingly improve clinical prognosis.Identification of new biomarkers set new challenges in translational research in order torefine the prognosis and adapt therapeutic procedures.Proton nuclear magnetic resonance spectroscopy-based metabolomics enable to identifyand quantify such metabolites by defining individual metabolic fingerprints.First part of this work was to explore the metabolic modifications of liver tissue to further establish diseases stages profiles.Second part was focused on the assessment of metabolic variations in HCC patients, by analyzing sequential serums taking, before and after a radiofrequency ablation curative treatment.Third and last part was centered on the validation of the quality parameters of the discriminant models used in multivariate statistical analysis.

Chez Arabidopsis thaliana, deux gènes codent des enzymes de branchement (BE) BE2.2 et BE2.1 responsables de la formation des liaisons α-1,6 de l’amidon transitoire synthétisé dans la feuille de la plante. Ces enzymes, appartenant à la famille GH13_8 de la classification CAZy, agissent en clivant une liaison α-1,4 d’un glucane puis en transférant la chaîne clivée en position α-1,6 selon un mécanisme d’action qui peut être intra ou intermoléculaire. Dans ce travail, une caractérisation enzymatique et structurale des BEs d’A. thaliana (classées de type II d’après leur séquence en acides aminés) a été réalisée et les résultats comparés à ceux de la BE d’E. coli (GlgB, enzyme de type I).L'état oligomérique, la forme en solution et l’organisation structurale des BEs ont été évalués par une approche SAXS. Par des analyses spectrophotométriques, le pH, la température, mais aussi le KM pour l’amylose et l’amylopectine ont été déterminés. Une analyse sur gel de polyacrylamide, en conditions natives, a permis d’évaluer le comportement électrophorétique des BEs en présence ou en absence de ces substrats et d’en déterminer leur constante d’affinité (Ks). Notre étude révèle que les BEs d’ A. thaliana ont plus d'affinité pour l’amylopectine que pour l’amylose contrairement à GlgB. En présence d’un substrat branché, des changements d’oligomérie et/ou de la conformation des BEs d’A. thaliana ont été observés. Finalement, des analyses en chromatographie échangeuse d'anions ont permis de déterminer la taille minimale du substrat nécessaire à l’activité des BEs et la taille des chaînes transférées. Les résultats obtenus pointent vers un mécanisme d’action intramoléculaire de BE2.2. / BE2.2 and BE2.1 are the two genetically independent branching enzymes (BE) isoforms involved in transitory starch synthesis in A. thaliana and belong to family GH13_8 (according to CAZy database). Both are classified as type II BE due to their amino acid sequence. In Arabidopsis leaves, they are the only enzymes that catalyze the formation of α-1,6 branch points by cleaving α-1,4 linkages and transferring the newly formed reducing end in α-1,6 position through an intra or intermolecular mechanism. In this work, we report in vitro enzymatic characterization and structural analysis of A. thaliana BEs, these results were compared to E. coli BE enzymatic analysis (GlgB, type I enzyme).Structural analysis using SAXS approach was used to evaluate A. thaliana BEs oligomeric state, shape in solution and to determine BE organization. In vitro enzymatic analyses were performed using spectrophotometry assays to establish their catalytic parameters such as pH, temperature and also KM for amylose and amylopectin. Native PAGE analyses were also used to assess BEs behaviour in the presence or absence of substrates and to determine their affinity constant (Ks) for amylopectin and amylose. Enzymatic characterization reveals that both A. thaliana BEs have more affinity for amylopectin than for amylose, contrary to GlgB. Moreover, interaction of A. thaliana BEs with branched substrates induces protein oligomerization and/or conformational changes. Finally, determination of the minimal length of their substrate and characterization of reaction products were performed using anions exchange chromatography analyses.Taken together, our data point to an intramolecular mechanism of action of BE2.2.

Proefschrift Universiteit van Amsterdam. / Met lit. opg. - Met samenvatting in het Nederlands.