No description available.

No description available.

No description available.

L'ozone (O3) troposphérique représente un enjeu environnemental majeur en raison de ses effets préjudiciables sur la santé humaine, la végétation et le climat. La formation photochimique de l'O3 suit une chimie non linéaire complexe, qui rend la mise en œuvre de mesures de réduction difficile. Les pouvoirs publics s’appuient sur la modélisation afin d’élaborer des stratégies de réduction des précurseurs d’O3, mais il existe encore des incertitudes importantes associées aux mécanismes chimiques utilisés dans les modèles. Une mesure directe de la vitesse de production de l'ozone, P(O3), permettrait de valider les mécanismes chimiques et de fournir des données en temps réel pour la réglementation. L'objectif principal de cette thèse a été (i) de développer nos connaissances sur la mesure de P(O3) et (ii) d’étudier la chimie de l'ozone en air ambiant. Dans ce contexte, un instrument a été développé pour la mesure de P(O3), caractérisé en laboratoire et déployé sur le terrain. Le principe de l'instrument est basé sur une mesure différentielle de Ox (O3+NO2) entre deux réacteurs d'échantillonnage, le premier opérant comme un réacteur "de référence", sans production d'ozone, et le second reproduisant la chimie de formation d’ozone de l’air ambiant. La caractérisation de l'instrument a impliqué des expériences de laboratoire et de modélisation afin d’évaluer la justesse des mesures. L’instrument a également été déployé lors de la campagne IRRONIC afin d’étudier la sensibilité de P(O3) avec NO. La comparaison des mesures de terrain avec des valeurs modélisées a permis d'évaluer les performances et les limites de cet instrument et d'évaluer la faisabilité de la mesure de P(O3). / Ground level ozone (O3) is a major environmental concern due to its detrimental impacts on human health, vegetation and climate. The photochemical formation of ozone follows a complex nonlinear chemistry that makes strategies for ozone reduction difficult to implement. Governments rely on atmospheric chemistry models to develop emission regulations, but there are still uncertainties associated with the chemical mechanisms used in these models. Direct measurements of ozone production rates, P(O3), is a new technique that can help validating current atmospheric chemical mechanisms and provide real-time data for emission regulations of ozone precursors. The main objective of this thesis was (i) to advance the understanding of P(O3) measurements and (ii) to investigate the ozone production chemistry in ambient air. In this context, an instrument capable of P(O3) measurements was developed, characterized in the laboratory and deployed in the field. The principle of the instrument is based on differential Ox (=O3+NO2) measurements between two sampling reactors, one acting as a “reference” reactor with no O3 production, and the other one reproducing the same O3 production chemistry than in ambient air. The characterization of this instrument was performed through laboratory and modelling experiments to assess the accuracy of P(O3) measurements. Finally, the instrument was deployed during the IRRONIC campaign to investigate the P(O3) sensitivity to NO in a forested area. Comparison between measured and modeled P(O3) values allowed to assess the performances and limitations of this new instrument and evaluate the feasibility of direct P(O3) measurements.

No description available.

The antral hormone gastrin has generally been regarded as a non antigenic molecule necessitating its conjugation with a large "carrier” to be an effective inducer of antibody. Such conjugation has normally taken the form of covalent binding to a highly antigenic molecule or ionic binding to an inert particle. Alternatively, some success has been achieved by the injection of impure antral extracts. This report describes four approaches to the problem of the induction of antibodies specific for gastrin. Initially, natural hog gastrin was obtained after the procedure of Gregory and Tracy (1964). The pure active hormone was modified by alkaline hydrolysis to liberate an N-terminal amino group for covalent conjugation. The modified gastrin, however, was not specifically identified or isolated in quantity. Consequently, pure and impure antral extracts, hemocyanin-bound synthetic human gastrin and latex-bound gastrin were applied to a variety of animals. Passive hemagglutination tests in ducks revealed titres of 400 to 1600 to both the pure and impure extracts but a series of four injections of pure gastrin into an antrectomized rabbit failed to raise detectable antibody. Injections of 3 mg. of SHG bound to hemocyanin was unsuccessful; antibody titre to the carrier molecule was high but no specificity appeared to be directed to the synthetic hapten. The immunization of chickens with latex-bound natural gastrin was more fruitful. Although a number of precipitin tests established the presence of antibodies to gastrin, it was apparent that the assay was inadequate as a sensitive test for the bivalent antigen. Furthermore, the antibody titre was not sufficiently high to be successfully applied to a radioimmunoassay. / Medicine, Faculty of / Cellular and Physiological Sciences, Department of / Graduate

La réduction des émissions polluantes des foyers aéronautiques est un enjeu majeur pour les motoristes. Afin de les accompagner dans cette tâche, il est nécessaire de développer des outils de simulation numérique permettant de prédire avec précision les émissions d'espèces chimiques en sortie du foyer. Pour cela, une description détaillée des réactions chimiques est nécessaire. Celle-ci est néanmoins incompatible avec la simulation des foyers industriels, compte tenu des puissances de calcul actuelles. C'est pourquoi il est nécessaire de recourir à des méthodes de réduction de la chimie qui préservent la capacité de prédire la concentration des polluants. La démarche consistant à tabuler la chimie nous a semblé appropriée pour aborder ces problèmes et son développement a fait l'objet de cette thèse. Un premier travail a été effectué afin de sélectionner dans la littérature les modèles permettant de traiter des écoulements réactifs turbulents diphasiques avec une approche de chimie tabulée. Par rapport à l’existant, des améliorations ont été apportées à la génération des tables chimiques, afin de prendre en compte l'effet du temps de résidence des gaz brûlés dans le foyer sur la formation des oxydes d'azote. Le couplage de la méthode avec un modèle de formation des suies a également été réalisé. La chimie tabulée permet d’avoir accès à la concentration des précurseurs de suie et des espèces oxydantes, quantités sur lesquelles s’appuie le modèle de formation des suies. Le modèle de chimie tabulée développé dans le cadre de cette thèse a été appliqué à la simulation d'une configuration représentative des foyers aéronautiques. Les concentrations d'oxydes d'azote, de particules de suie, mais aussi de monoxyde de carbone et d'hydrocarbures imbrûlés prédites par les calculs ont été comparées aux résultats expérimentaux. Un bon accord avec l'expérience est observé concernant la topologie du champ de suie et l'allure des profils de concentration de polluants en sortie. Néanmoins, les niveaux de concentration obtenus par les simulations diffèrent des résultats expérimentaux. Cela est imputable notamment à une erreur de prédiction du champ de température qui n'est pas due à l'approche de chimie-tabulée puisque une erreur similaire a été observée avec un autre modèle de combustion. / The reduction of pollutant emissions of aeronautical combustion chambers is a major issue for engine manufacturers. In order to support them in this task, it is necessary to develop numerical simulation tools able to predict accurately chemical species emissions at the chamber outlet. To achieve this, a detailed description of the chemical reactions is necessary. Nevertheless, considering the current computer capabilities, this description is not presently affordable. This is why the use of chemistry reduction methods preserving the capability to predict pollutants species is necessary. The method of tabulated chemistry is a good candidate to tackle these problems and therefore is used as the basis of model developments achieved in the framework of this PhD thesis. A preliminary work has been made to select in the literature tabulated chemistry methods applying to turbulent reactive two-phase flows. The technique to create the chemical tables has been improved in order to take into account the effect of the residence time of the burnt gases on nitrogen oxides formation. The coupling of the method with a soot model has also been achieved. The tabulated chemistry gives access to the concentration of soot precursors and oxidizers, quantities which are required by the model used for the soot prediction. The developed tabulated chemistry model has been applied to the simulation of a configuration representative of aeronautical combustors. The concentration of nitrogen oxides, soot particles, carbon monoxide and unburnt hydrocarbons predicted by the numerical simulations have been compared to experimental results. The topology of the soot volume fraction field and the shape of pollutant concentrations profiles at the outlet agree quite well with the experiments. Nevertheless, concentration levels obtained from the simulations differ from the experimental results. This can be imputed to the error in the prediction of the temperature field that is independent of the combustion model, since a similar error was observed with another combustion model.

La présente thèse porte sur l’individualisation et la singularisation des parcours de formation d’adultes salariés en reprise de formation. L’auteure commence par donner la parole à des usagers du dispositif, en prenant soin d’expliquer de manière très précise la méthodologie qu’elle utilise. Cela donne à voir des mondes qu’elle nomme juridique, domestique, académique, personnel et invite à comprendre comment les sujets construisent leur identité à la croisée des mondes et comment ils sont aussi croiseurs de mondes. Les mots « Sujet » et « Monde » font alors l’objet d’un travail de conceptualisation et d’une rencontreavec la communauté scientifique spécialisée dans ce champ de recherche. Après quoi une étude des mondes juridique et académique vécues par les personnes enquêtées permet de comprendre ce que sont les mondes d’arrière-fond à l’oeuvre dans le parcours du sujet croiseur de monde et comment le monde personnel, à la fois, est travaillé par ses mondes mais les travaille aussi d’une certaine manière. En conclusion, une synthèse est proposée ainsi que des pistes de recherche. / The present thesis focuses on individualizing and singularizing the training programmes of wageearning adults resuming education. The author beguins by handing over to some users of the scheme, making sure that she explains very accurately the methodology she uses. It makes us see worlds she calls juridical, domestic, personal and leads to understand how the subjects build up their identities at the crossing of worlds and how they also cross the worlds.The words “subject” and “world” are then the subject of conceptualizing process and meeting with the scientific community specialized in this field of research.Afterwards a study of juridical and academic worlds lived by the investigated on persons enables to understand what the background worlds at work are in the path of the crossing-world subject and how the personal world is both worked by these worlds and in a way works them too. To conclude, a synthesis as well as research leads are suggested.

This thesis analyses the sociological and historical genesis of enterprise skill formation in South Africa and its effective coordination. South Africa’s late nineteenth century development as an emerging economy contributed to the state often taking the lead and being at the forefront of efforts to ensure coordination in enterprise skill formation. But gradually, concerns shaped by issues related to labour supply motivated leaders in firms and enterprises to forge their own imprint on the coordination of enterprise skill formation. The thesis also shows how these concerns with the coordination of enterprise skill formation involved intellectuals and professionals who attempted to intervene on these matters. The thesis proceeds to elaborate the unique institutional architecture which was constructed at various junctures in the history of South Africa’s human resource and skill formation journey. Furthermore the thesis gives an insight into the coordination of enterprise skill formation which occurred in the period of apartheid induced reforms. The evidence however shows that even when regimes change and new political orders are established, it does not end the necessity for continuity in the coordination of enterprise skill formation. As is to be expected, the institutional, regulatory and instrumental content of the coordination of enterprise skill formation is more complex in the contemporary period (circa. 2017) than it was in the 1920s and 1930s. However, the goal striven toward then was for a more streamlined process which could contribute to a change and improvement in the existing practice of enterprise skill formation. Evidence shows that this has been ongoing for over a century. The thesis gives an intricate and detailed insight into the process of building a new coordinated skills development system that was intended to ensure the coordination of enterprise skill formation under a democratic post-apartheid political dispensation. In this period a levy-grant system underwritten by a national skills levy has been a central instrument of direct coordination into enterprise skill formation. The analysis that is provided traces the iterative steps that were treaded by policy makers and policy thinkers from at least the early 1920s as they confronted what may have appeared as an elusive enterprise skill formation process. This analysis is done with a great deal more depth for the period since the early 1990s.

Includes bibliographical references (pages 139-143). / The central theme of this study concerns the use of classification schemes on weather modification experiments designed to investigate the possibility of increasing rainfall from individual cumuli or cumulus cloud systems. The principal objectives of these experiments are the evaluation of treatment effects and the identification of situations where seeding with artificial ice-nuclei is likely to have positive results. The classification of experimental units into categories that are associated with significantly different physical processes aids the evaluation process and the formulation of seeding strategies in the desired manner. As part of this study a classification scheme, which stratifies convective events on the basis of the synoptic situations which give rise to and maintain the convection, is formulated. In chapter seven and eight this scheme and another scheme presently being employed on a cumulus cloud weather modification experiment are examined statistically. Investigations show that the formulated scheme attains the objectives of classification to a greater degree. Certain attributes of the second scheme, permit the development of a classification procedure whereby the most effective stratification of experimental units can be accomplished.