L'hydrogène moléculaire diffus et froid peut être l'un des candidats ultimes à la composante baryonique cachée de la Voie Lactée. Nous décrivons une nouvelle voie de recherche de matière transparente dans le disque et le halo galactiques, qui exploite les effets de diffraction et de réfraction de la lumière des étoiles d'arrière-plan. En simulant le retard de phase induit par un milieu turbulent, nous avons calculé la figure d'éclairement sur la terre d'une source étendue pour une bande passante donnée. Nous montrons que dans les cas favorables, la luminosité apparente d'une étoile d'arrière-plan peut être soumise à des fluctuations stochastiques de l'ordre de quelques pour cent sur une échelle de temps caractéristique de quelques minutes. Nous avons recherché de tels effets de scintillation, induits par du gaz moléculaire de nébuleuses visibles (sombres), ainsi que par d'hypothétiques (invisibles) clumpuscules d'hydrogène moléculaire froid du halo, pendant deux nuits avec le détecteur infra-rouge SOFI au foyer du télescope NTT de l'ESO. Parmi les quelques milliers d'étoiles surveillées, nous avons détecté un objet dont les variations sont compatibles avec un fort effet de scintillation à travers une structure turbulente de la nébuleuse B68. Comme par ailleurs aucun effet de scintillation n'a été trouvé vers le Petit Nuage de Magellan, nous sommes en mesure d'établir des limites supérieures sur la contribution des clumpuscules de gaz à la masse du halo galactique. Nous montrons qu'une surveillance à cadence élevée dans la bande visible avec un télescope de diamètre supérieur à quatre mètres équipé d'une caméra à lecture rapide devrait permettre, avec une exposition de quelque millions (d'heures x étoiles), de quantifier ou de borner d'une façon très significative la contribution du gaz moléculaire turbulent au halo Galactique. / Cool molecular hydrogen H2 may be the ultimate possible constituent to the Milky-Way missing baryon. We describe a new way to search for such transparent matter in the Galactic disc and halo, through the diffractive and refractive effects on the light of background stars. By simulating the phase delay induced by a turbulent medium, we computed the corresponding illumination pattern on the earth for an extended source and a given passband. We show that in favorable cases, the light of a background star can be subjected to stochastic fluctuations of the order of a few percent at a characteristic time scale of a few minutes. We have searched for scintillation induced by molecular gas in visible dark nebulae as well as by hypothetical halo clumpuscules of cool molecular hydrogen (H2_He) during two nights, using the NTT telescope and the IR SOFI detector. Amongst a few thousands of monitored stars, we found one light-curve that is compatible with a strong scintillation effect through a turbulent structure in the B68 nebula. Because no candidate were found toward the SMC, we are able to establish upper limits on the contribution of gas clumpuscules to the Galactic halo mass. We show that the short time-scale monitoring of a few 10^6 star _ hour in the visible band with a >4 m telescope and a fast readout camera should allow one to interestingly quantify or constrain the contribution of turbulent molecular gas to the Galactic halo.

A quantitative and descriptive type of study design was followed using structured self-administered questionnaires distributed among 84 conveniently selected male adolescent learners from Nanogang Community Junior Secondary School (NCJSS) in Gaborone. The purpose of this study was to describe factors that influence the uptake of safe male circumcision (SMC) as a human immune-deficiency virus (HIV) prevention strategy among male adolescent learners. The study findings show that protection from HIV and other sexually transmitted infections (STIs) was found to be the main reason for adolescent learners undergoing male circumcision (MC) (p<.01). Reasons such as maintenance of genital hygiene, culture, religion, and the enhancement of sexual pleasure were not found to be significant factors. Misconceptions such as the belief that girls do not like circumcised partners were found to be the main reason for adolescent learners not undergoing MC (p<.05). A number of factors which were claimed in previous studies to be obstacles for the uptake of MC, such as surgical complications, peer pressure, stigma, and discrimination, were not found to be major obstacles / Health Studies / M.A. (Public Health)

L'instrumentation Cigale basé sur un interféromètre de Perot-Fabry permet d'obtenir une spectroscopie de la raie H alpha dans un grand champ. Cette instrumentation est utilisée sur un petit télescope pour observer la galaxie et le Petit Nuage de Magellan pour comprendre leur structure tridimensionnelle. Nous présentons un multispectromètre a dispersion croisée permettant de couvrir le domaine spectral d'un réseau avec la grande résolution spectrale du Perot-Fabry, et ceci simultanément pour les différents points d'une source bidimensionnelle. Il est integral de champ (au sens de Courtes 1987), par la trame de lentilles qui permet d'isoler des points contigus d'une image. Il est multicanal, intégral spectral (au sens de Chabbal 1958), car il permet d'obtenir tous les éléments spectraux au cours du balayage pas à pas d'un seul ordre du Perot-Fabry. Pour 40 canaux de balayage, on obtient simultanément 400 spectres de résolution spectrale R30000 sur un domaine de 200 NM environ dans le visible pour un récepteur de 20002000 éléments.

Ce travail porte sur la simulation numérique et la modélisation du comportement thermo-mécanique des matériaux composites renforcés par des fibres. Spécifiquement les matériaux SMC (Sheet Moulding Compound) sont utilisés dans le processus de moulage par compression pour construire des pièces automobiles de haute performance. Ce travail est divisé en quatre chapitres, décrivant tout d’abord un modèle thermo-mécanique entièrement couplé pour les matériaux SMC standards et innovants à haute concentration en fibres (> 25% en volume). Le SMC est traité comme un mélange incompressible de fibre et de résine complété éventuellement par une phase de porosité compressible. Son anisotropie est modélisée au moyen de tenseurs structurels. La cinétique de réaction et de consolidation de la pièce est également modélisée et étudiée. Les données expérimentales mécaniques et thermiques enregistrées sur des échantillons de matériaux SMC sont comparées au modèle et à la solution numérique fournie par ce travail. D’un point de vue numérique, nous utilisons la méthode des domaines immergées o`u chaque phase est distinguée par une fonction distance signée. Nous décrivons le procédé de moulage par compression en proposant une résolution compressible anisotrope unifiée capable de décrire la transition compressible / incompressible du matériau SMC sous déformation. Cela permet de décrire la réponse mécanique du SMC et de prédire localement la consolidation (durcissement) de la pièce le long du cycle thermique. / This work deals with the numerical simulation and modeling of thermomechanical analysis of fiber reinforcedcomposites materials. Specifically for SMC (Sheet Molding Compound) materials that are used in compression molding processes to build automotive high performance parts. The work is divided into fourchapters, firstly describing a fully coupled thermo-mechanical model for standard SMC materials and for innovative SMC with high fiber concentration (> 25% in volume). The SMC is treated as an incompressible mixtureof fibers and paste complemented by a compressible porosity phase. Its anisotropy is modeled by means of structural tensors. Kinetic of reaction and consolidation of the part is also modeled and studied. Mechanicaland thermal experimental data recorded on samples of SMC materials are compared to the model and numerical solution provided in this work. A numerical framework, we use the immersed boundary method and the level set method. We describe the compression molding process by proposing an unified anisotropic compressible resolution able to describe the transition between compressible/ incompressible of SMC materials under deformation. We are able to describe the mechanical response of the SMC and to predict locally the consolidation (curing) of thepart throughout the thermal cycle.

L’hypertension artérielle pulmonaire idiopathique (HTAPi) se caractérise par une une augmentation des résistances vasculaire, une augmentation de la PAPm et à long terme une insuffisance ventriculaire droite. La dysfonction endothéliale est l’événement initial de la maladie. Elle résulte d’un déséquilibre de synthèse des molécules vasoactives, d’un défaut de production de facteurs de croissance. Ces perturbations affectent directement le muscle lisse adjacent qui en réponse produit une vasoconstriction et une prolifération excessive. Le muscle lisse possède également ses propres anomalies intrinsèques contribuant à amplifier son phénotype vasoconstrictif et prolifératif. Actuellement, les thérapeutiques de l’HTAP ne permettent pas de corriger le remodelage vasculaire et les données cliniques soulignent leur manque d’efficacité en ce qui concerne la survie des patients. Ces travaux de doctorat ont visé à proposer de nouvelles approches thérapeutiques. Dans cette optique, nous nous sommes intéressés à l’implication de la kinase Src dans la pathogenèse de l’HTAP. Nous avons montré que l’augmentation du niveau de Src dans les CML-AP été associée au développement de l’HTAPi. Aussi, nous avons montré que l’inhibition de Src, avec des molécules spécifiques, prévient la prolifération des CML-AP in vitro et réverse l’HTAP dans un modèle expérimental induit par la monocrotaline. Dans un second temps, nous nous sommes intéressés à l’inhibition des récepteurs adrénergiques dans l’HTAP. Nous avons comparé les effets du nébivolol, un β-bloquant de troisième génération qui possède des propriétés vasodilatatrices, aux effets du métoprolol, un β-bloquant de deuxième génération. Nous avons montré que le nébivolol, contrairement au métoprolol, a des effets positifs sur la dysfonction endothéliale, la relaxation des artères pulmonaires et sur le modèle expérimental de l’HP induite par la monocrotaline. Ainsi au cours de ce doctorat, nous avons caractérisé deux stratégies thérapeutiques différentes qui ont montré toutes deux un potentiel intéressant pour le traitement de l’HTAP. / Idiopathic Pulmonary Arterial Hypertension (iPAH) is characterized by an increased vascular resistance, increase pulmonary artery pressure, and at long term, a right ventricular failure. Endothelial dysfunction is the initial event of this pathology. It is a result of altered vasoactive molecules synthesis, altered growth factors production. These alterations directly affect the neighboring smooth muscle which produces an important vasoconstriction and a significant proliferation. Also, the smooth muscle has its own intrinsic abnormalities that participate in its vasoconstriction and proliferation phenotypes.It is to note that to date, PAH treatment strategies do not improve the vascular remodeling. Moreover, clinical results show no efficiency of these treatments on patient survival. Accordingly, this thesis studies have targeted new and better therapeutic approaches. To this aim, we have fist oriented our research toward the involvement of Src kinase in PAH pathology. We found that increased Src level in the Pulmonary Artery Smooth Muscle Cells (PA-SMC) was associated with PAH development. Also, we have showed that, in vitro, Src inhibition, with specific molecules, prevent PA-SMC proliferation and revert PAH in a monocrotaline-induced experimental model. The second aim of this thesis work was oriented toward beta-adrenergic receptor inhibition in PAH. We have compared the effect of both the nebivolol, which is a third generation of b-blockers that has a vasodilation proterties, and metoprolol, which is a second generation of -blockers. Our results show that, as opposite to metoprolol, nebivolol has positive effects on endothelial dysfunctions, pulmonary artery relaxation, and on monocrotaline-induced PH in rats.Therefore, during this thesis, we have characterized two different therapeutic strategies that both show interesting potential in PAH treatment.

Cool molecular hydrogen H2 may be the ultimate possible constituent to the Milky-Way missing baryon. We describe a new way to search for such transparent matter in the Galactic disc and halo, through the diffractive and refractive effects on the light of background stars. By simulating the phase delay induced by a turbulent medium, we computed the corresponding illumination pattern on the earth for an extended source and a given passband. We show that in favorable cases, the light of a background star can be subjected to stochastic fluctuations of the order of a few percent at a characteristic time scale of a few minutes. We have searched for scintillation induced by molecular gas in visible dark nebulae as well as by hypothetical halo clumpuscules of cool molecular hydrogen (H2_He) during two nights, using the NTT telescope and the IR SOFI detector. Amongst a few thousands of monitored stars, we found one light-curve that is compatible with a strong scintillation effect through a turbulent structure in the B68 nebula. Because no candidate were found toward the SMC, we are able to establish upper limits on the contribution of gas clumpuscules to the Galactic halo mass. We show that the short time-scale monitoring of a few 10^6 star _ hour in the visible band with a >4 m telescope and a fast readout camera should allow one to interestingly quantify or constrain the contribution of turbulent molecular gas to the Galactic halo.

What if the emergency response directly knew exactly where to go and what to do if a road accident occured? During the last ten years the number of motorcyclists in Sweden has doubled. Every year, more than 300 riders are seriously injured and over 40 die in road accidents. Being found in time is critical to increase the chance of survival. The goal of this project is to use design methods to find a solution that enables a fast and adequate emergency response for motorcyclists and other unprotected road users. / Vad hade hänt om akutsjukvårdare direkt kände till var en olycka inträffat och vilken vårdinsats som behövdes? Under de senaste tio åren har antalet motorcyklister i Sverige fördubblats. Varje år skadas över 300 förare allvarligt, och över 40 omkommer i trafikolyckor. Att bli hittad i tid är kritiskt för att öka chansen för överlevnad. Målet med det här projektet är att med designmetoder hitta ett sätt att möjliggöra en snabb och adekvat räddningsinsats för motorcyklister och andra oskyddade motortrafikanter.

Many analysts believe that problems in the United States housing market initiated the 2007-2009 global financial crisis. In this regard, the subprime mortgage crisis (SMC) shook the foundations of the financial industry by causing the failure of many iconic Wall Street investment banks and prominent depository institutions. This crisis stymied credit extension to households and businesses thus creating credit crunches and, ultimately, a global recession. This thesis specifically discusses the SMC and its components, causes, consequences and cures in relation to subprime mortgage origination, data as well as bank bailouts. In particular, the SMC has highlighted the fact that risk, credit ratings, profit and valuation as well as capital regulation are important banking considerations. With regard to risk, the thesis discusses credit (including counterparty), market (including interest rate, basis, prepayment, liquidity and price), tranching (including maturity mismatch and synthetic), operational (including house appraisal, valuation and compensation) and systemic (including maturity transformation) risks. The thesis introduces the IDIOM hypothesis that postulates that the SMC was largely caused by the intricacy and design of subprime agents, mortgage origination that led to information problems (loss, asymmetry and contagion), valuation opaqueness and ineffective risk mitigation. It also contains appropriate examples, discussions, timelines as well as appendices about the main results on the aforementioned topics. Numerous references point to the material not covered in the thesis, and indicate some avenues for further research. In the sequel, the banks that we study are subprime interbank lenders (SILs), subprime originators (SORs), subprime dealer banks (SDBs) and their special purpose vehicles (SPVs) such as Wall Street investment banks and their special structures as well as subprime investing banks (SIBs). Furthermore, the primary subprime agents that we consider are house appraisers (HAs), mortgage brokers (MBs), mortgagors (MRs), servicers (SRs), trustees, underwriters and credit enhancement providers (CEPs). Also, the insurers involved in the subprime market are originator mortgage insurers (OMIs) and monoline insurers (MLIs). The main components of the SMC are MRs, the housing market, SDBs/hedge funds/money market funds/SIBs, the economy as well as the government (G) and central banks. Here, G either plays a regulatory, bailout or policymaking role. Most of the aforementioned banks and agents are assumed to be risk neutral with SOR being the exception since it can be risk (and regret) averse on occasion. The three main aspects of the SMC - subprime mortgage origination, data and bailouts - that we cover in this thesis and the chapters in which they are found are outlined below. In Chapter 2, we discuss the dynamics of SORs' capital, information, ratings, risk and valuation under mortgage origination. In particular, we model subprime mortgages that are able to fully amortize, voluntarily prepay or default and construct a discrete-time model for SOR risk and profit incorporating costs of funds and mortgage insurance as well as loan losses. Furthermore, a constrained optimal valuation problem for SORs under mortgage origination is solved. In addition, we show how high loan-to-value ratios curtailed the refinancing of subprime mortgages, while low ratios imply favorable house equity for subprime MRs. Chapter 2 also explores the relationship between Basel capital regulation and the SMC. This involves studying bank credit and capital under Basel regulation. Further issues dealt with are the quantity and pricing of subprime mortgages as well as credit ratings under Basel capital regulation. A key problem is whether Basel capital regulation exacerbated the SMC. Very importantly, the thesis answers this question in the affirmative. Chapter 3 contains subprime data not presented in Chapters 2. We present other mortgage data that also have connections with the main subprime issues raised. In Chapter 4, a troubled SOR's recapitalization by G via subprime bank bailouts is discussed. Our research supports the view that if SOR is about to fail, it will have an incentive not to extend low risk mortgages but rather high risk mortgages thus shifting risk onto its creditors. Here, for instance, we analyze the efficiency of purchasing toxic structured mortgage products from troubled SORs as opposed to buying preferred and common equity. In this regard, we compare the cases where SORs' on-balance sheet mortgages are fully amortizing, voluntarily prepaying (refinancing and equity extraction) and involuntarily prepaying (defaulting). If bailing out SORs considered to be too big to fail involves buying assets at above fair market values, then these SORs are encouraged ex-ante to invest in high risk mortgages and toxic structured mortgage products. Contrary to the policy employed by G, purchasing common (preferred) equity is always the most (least) ex-anteand ex-post-efficient type of capital injection. Our research confirms that this is true irrespective of whether SOR volunteers for recapitalization or not. In order to understand the key results in Chapters 2 to 4, a working knowledge of discrete-time stochastic modeling and optimization is required. The work presented in this thesis is based on a book (see [103]), 2 peer-reviewed international journal articles (see [51] and [105]), 2 peer-reviewed chapters in books (see [104] and [110]) and 4 peer-reviewed conference proceedings paper (see [23], [106], [107] and [109]). / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2011.

Many analysts believe that problems in the United States housing market initiated the 2007-2009 global financial crisis. In this regard, the subprime mortgage crisis (SMC) shook the foundations of the financial industry by causing the failure of many iconic Wall Street investment banks and prominent depository institutions. This crisis stymied credit extension to households and businesses thus creating credit crunches and, ultimately, a global recession. This thesis specifically discusses the SMC and its components, causes, consequences and cures in relation to subprime mortgage origination, data as well as bank bailouts. In particular, the SMC has highlighted the fact that risk, credit ratings, profit and valuation as well as capital regulation are important banking considerations. With regard to risk, the thesis discusses credit (including counterparty), market (including interest rate, basis, prepayment, liquidity and price), tranching (including maturity mismatch and synthetic), operational (including house appraisal, valuation and compensation) and systemic (including maturity transformation) risks. The thesis introduces the IDIOM hypothesis that postulates that the SMC was largely caused by the intricacy and design of subprime agents, mortgage origination that led to information problems (loss, asymmetry and contagion), valuation opaqueness and ineffective risk mitigation. It also contains appropriate examples, discussions, timelines as well as appendices about the main results on the aforementioned topics. Numerous references point to the material not covered in the thesis, and indicate some avenues for further research. In the sequel, the banks that we study are subprime interbank lenders (SILs), subprime originators (SORs), subprime dealer banks (SDBs) and their special purpose vehicles (SPVs) such as Wall Street investment banks and their special structures as well as subprime investing banks (SIBs). Furthermore, the primary subprime agents that we consider are house appraisers (HAs), mortgage brokers (MBs), mortgagors (MRs), servicers (SRs), trustees, underwriters and credit enhancement providers (CEPs). Also, the insurers involved in the subprime market are originator mortgage insurers (OMIs) and monoline insurers (MLIs). The main components of the SMC are MRs, the housing market, SDBs/hedge funds/money market funds/SIBs, the economy as well as the government (G) and central banks. Here, G either plays a regulatory, bailout or policymaking role. Most of the aforementioned banks and agents are assumed to be risk neutral with SOR being the exception since it can be risk (and regret) averse on occasion. The three main aspects of the SMC - subprime mortgage origination, data and bailouts - that we cover in this thesis and the chapters in which they are found are outlined below. In Chapter 2, we discuss the dynamics of SORs' capital, information, ratings, risk and valuation under mortgage origination. In particular, we model subprime mortgages that are able to fully amortize, voluntarily prepay or default and construct a discrete-time model for SOR risk and profit incorporating costs of funds and mortgage insurance as well as loan losses. Furthermore, a constrained optimal valuation problem for SORs under mortgage origination is solved. In addition, we show how high loan-to-value ratios curtailed the refinancing of subprime mortgages, while low ratios imply favorable house equity for subprime MRs. Chapter 2 also explores the relationship between Basel capital regulation and the SMC. This involves studying bank credit and capital under Basel regulation. Further issues dealt with are the quantity and pricing of subprime mortgages as well as credit ratings under Basel capital regulation. A key problem is whether Basel capital regulation exacerbated the SMC. Very importantly, the thesis answers this question in the affirmative. Chapter 3 contains subprime data not presented in Chapters 2. We present other mortgage data that also have connections with the main subprime issues raised. In Chapter 4, a troubled SOR's recapitalization by G via subprime bank bailouts is discussed. Our research supports the view that if SOR is about to fail, it will have an incentive not to extend low risk mortgages but rather high risk mortgages thus shifting risk onto its creditors. Here, for instance, we analyze the efficiency of purchasing toxic structured mortgage products from troubled SORs as opposed to buying preferred and common equity. In this regard, we compare the cases where SORs' on-balance sheet mortgages are fully amortizing, voluntarily prepaying (refinancing and equity extraction) and involuntarily prepaying (defaulting). If bailing out SORs considered to be too big to fail involves buying assets at above fair market values, then these SORs are encouraged ex-ante to invest in high risk mortgages and toxic structured mortgage products. Contrary to the policy employed by G, purchasing common (preferred) equity is always the most (least) ex-anteand ex-post-efficient type of capital injection. Our research confirms that this is true irrespective of whether SOR volunteers for recapitalization or not. In order to understand the key results in Chapters 2 to 4, a working knowledge of discrete-time stochastic modeling and optimization is required. The work presented in this thesis is based on a book (see [103]), 2 peer-reviewed international journal articles (see [51] and [105]), 2 peer-reviewed chapters in books (see [104] and [110]) and 4 peer-reviewed conference proceedings paper (see [23], [106], [107] and [109]). / Thesis (Ph.D. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2011.

A quantitative and descriptive type of study design was followed using structured self-administered questionnaires distributed among 84 conveniently selected male adolescent learners from Nanogang Community Junior Secondary School (NCJSS) in Gaborone. The purpose of this study was to describe factors that influence the uptake of safe male circumcision (SMC) as a human immune-deficiency virus (HIV) prevention strategy among male adolescent learners. The study findings show that protection from HIV and other sexually transmitted infections (STIs) was found to be the main reason for adolescent learners undergoing male circumcision (MC) (p<.01). Reasons such as maintenance of genital hygiene, culture, religion, and the enhancement of sexual pleasure were not found to be significant factors. Misconceptions such as the belief that girls do not like circumcised partners were found to be the main reason for adolescent learners not undergoing MC (p<.05). A number of factors which were claimed in previous studies to be obstacles for the uptake of MC, such as surgical complications, peer pressure, stigma, and discrimination, were not found to be major obstacles / Health Studies / M.A. (Public Health)