Please read the abstract in the dissertation. Copyright / Dissertation (MEng)--University of Pretoria, 2010. / Chemical Engineering / unrestricted

HIV/AIDS rates among Asian and Pacific Islanders (APIs) have increased steadily in recent years. The Health Resources and Services Administration reported in 2011 that people living with HIV/AIDS experience psychiatric disorders at a rate 4 to 8 times higher than the general population, with as many as 60% experiencing depression. Studies show that short-term psychotherapy reduces depression and anxiety in people with HIV/AIDS, and studies have indicated that patients have better health outcomes when they receive psychotherapy in conjunction with medical treatment. It is not known how social support relates to psychotherapy attendance or health outcomes as measured by CD4 and viral load among people who are APIs and have HIV/AIDS. APIs comprise a group that does not readily engage with mental health services, thus warranting focused research attention. The purpose of this quantitative, causal, comparative study was (a) to examine the psychotherapy attendance rates of APIs and non-APIs who have HIV/AIDS, and (b) to identify the impact of social support on attendance rates and health outcomes such as CD4 and viral load. The data collected from anonymous medical files at a community health center, 993 number of records reviewed, analyzing the data using descriptive and inferential statistics in order to identify factors that increase psychotherapy attendance rates of people who are APIs and have HIV/AIDS. The study findings demonstrated that non-APIs have higher psychotherapy attendance rates over time compared to APIs, regardless of social support from case workers for attending. Positive social change for this group indicates further examination of the meaning and outcomes for API under these circumstances, with recommendation for use of qualitative data gathering the perspectives of API themselves.

No description available.

No description available.

Les structures planaires de grandes tailles sont de plus en plus utilisées dans les applications des satellites et des radars. Deux grands types de ces structures à savoir les FSS et les Reflectarrays sont particulièrement les plus intéressants dans les domaines de la conception RF. Mais en raison de leur grande taille et de la complexité des cellules élémentaires, l‘analyse complète de ces structures nécessite énormément de mémoire et des temps de calcul excessif. Par conséquent, les techniques classiques basées sur maillage linéaire soit ne parviennent pas à simuler de telles structures soit, exiger des ressources non disponibles à un concepteur d'antenne. Une technique appelée « technique par changement d'échelle » tente de résoudre ce problème par partitionnement de la géométrie du réseau par de nombreux domaines imbriqués définis à différents niveaux d'échelle du réseau. Le multi-pôle par changement d'échelle, appelé « Scale changing Network (SCN) », modélise le couplage électromagnétique entre deux échelles successives, en résolvant une formulation intégral des équations de Maxwell par une technique basée sur la méthode des moments. La cascade de ces multi-pôles par changement d'échelle, permet le calcul de la matrice d'impédance de surface de la structure complète qui peut à son tour être utilisées pour calculer la diffraction en champ lointain. Comme le calcul des multi-pôles par changement d'échelle est mutuellement indépendant, les temps d'exécution peuvent être réduits de manière significative en parallélisant le calcul. Par ailleurs, la modification de la géométrie de la structure à une échelle donnée nécessite seulement le calcul de deux multi-pôles par changement d'échelle et ne requiert pas la simulation de toute la structure. Cette caractéristique fait de la SCT un outil de conception et d'optimisation très puissant. Des structures planaires uniformes et non uniformes excité par un cornet ont étés modélisés avec succès, avec des temps de calcul délais intéressants, employant les ressources normales de l'ordinateur. / Large sized planar structures are increasingly being employed in satellite and radar applications. Two major kinds of such structures i.e. FSS and Reflectarrays are particularly the hottest domains of RF design. But due to their large electrical size and complex cellular patterns, full-wave analysis of these structures require enormous amount of memory and processing requirements. Therefore conventional techniques based on linear meshing either fail to simulate such structures or require resources not available to a common antenna designer. An indigenous technique called Scale-changing Technique addresses this problem by partitioning the cellular array geometry in numerous nested domains defined at different scale-levels in the array plane. Multi-modal networks, called Scale-changing Networks (SCN), are then computed to model the electromagnetic interaction between any two successive partitions by Method of Moments based integral equation technique. The cascade of these networks allows the computation of the equivalent surface impedance matrix of the complete array which in turn can be utilized to compute far-field scattering patterns. Since the computation of scale-changing networks is mutually independent, execution times can be reduced significantly by using multiple processing units. Moreover any single change in the cellular geometry would require the recalculation of only two SCNs and not the entire structure. This feature makes the SCT a very powerful design and optimization tool. Full-wave analysis of both uniform and nonuniform planar structures has successfully been performed under horn antenna excitation in reasonable amount of time employing normal PC resources.

Les structures planaires de tailles finies sont de plus en plus utilisées dans les applications des satellites et des radars. Deux grands types de ces structures sont les plus utilisés dans le domaine de la conception RF à savoir Les Surfaces Sélectives en Fréquence (FSS) et les Reflectarrays. Les FSSs sont un élément clé dans la conception de systèmes multifréquences. Elles sont utilisées comme filtre en fréquence, et trouvent des applications telles que les radômes, les réflecteurs pour antenne Cassegrain, etc. Les performances des FSSs sont généralement évaluées en faisant l'hypothèse d'une FSS de dimension infinie et périodique en utilisant les modes de Floquet, le temps de calcul étant alors réduit quasiment à celui de la cellule élémentaire. Plusieurs méthodes permettant la prise en compte de la taille finie des FSSs ont été développées. La méthode de Galerkin basée sur l'approche rigoureuse permet la prise en compte des interactions entre les différents éléments du réseau, mais cette technique ne fonctionne que pour les FSSs de petite taille, typiquement 3x3 éléments. Pour les grands réseaux, cette méthode n'est plus adaptée, car le temps de calcul et l'exigence en mémoire deviennent trop grands. Donc, une autre approche est utilisée, celle basée sur la décomposition spectrale en onde plane. Elle permet de considérer un réseau fini comme un réseau périodique infini, illuminé partiellement par une onde plane. Avec cette approche, des FSSs de grande taille sont simulées, mais elle ne permet pas dans la plupart des cas, de prendre en compte les couplages qui existent entre les différentes cellules du réseau, les effets de bord non plus. La simulation des FSSs par les méthodes numériques classiques basées sur une discrétisation spatiale (méthode des éléments finis, méthode des différences finies, méthode des moments) ou spectrale (méthodes modales) aboutit souvent à des matrices mal conditionnées, des problèmes de convergence numérique et/ou des temps de calcul excessifs. Pour éviter tous ces problèmes, une technique appelée technique par changements d'échelle tente de résoudre ces problèmes. Elle est basée sur le partitionnement de la géométrie du réseau en plusieurs sous-domaines imbriqués, définis à différents niveaux d'échelle du réseau. Le multi-pôle de changement d'échelle, appelé Scale-Changing Networks (SCN), modélise le couplage électromagnétique entre deux échelles successives. La cascade de ces multi-pôles de changement d'échelle, permet le calcul de la matrice d'impédance de surface de la structure complète et donc la modélisation globale du réseau. Ceci conduit à une réduction significative en termes de temps de calcul et d'espace mémoire par rapport aux méthodes numériques classiques. Comme le calcul des multi-pôles de changement d'échelle est mutuellement indépendant, les temps d'exécution peuvent encore être réduits de manière significative en parallélisant le calcul. La SCT permet donc de modéliser des FSSs Finies tout en prenant en compte le couplage entre les éléments adjacents du réseau. / The finite size planar structures are increasingly used in applications of satellite and radar. Two major types of these structures are the most used in the field of RF design ie Frequency Selective Surfaces (FSS) and the Reflectarrays. The FSSs are a key element in the design of multifrequency systems. They are used as frequency filter, and find applications such as radomes, reflector Cassegrain antenna, etc.. The performances of FSSs are generally evaluated by assuming an infinite dimensional FSS using periodic Floquet modes, the computation time is then reduced almost to that of the elementary cell. Several methods have been developed for taking into account the finite dimensions of arrays. For example the Galerkin method uses a rigorous element by element approach. With this method, the exact interactions between the elements are taken into account but this technique works only for small FSS, typically 3x3 elements. For larger surfaces, this method is no more adapted. The computation time and the memory requirement become too large. So another approach is used based on plane wave spectral decomposition. It allows considering the finite problem as a periodic infinite one locally illuminated. With this approach, large FSS are indeed simulated, but the exact interactions between the elements are not taken into account, the edge effects either. The simulation of FSS by conventional numerical methods based on spatial meshing (finite element method, finite difference, method of moments) or spectral (modal methods) often leads in the practice to poorly conditioned matrices, numerical convergence problems or/and excessive computation time. To avoid these problems, a new technique called Scale Changing Technique attempts to solve these problems. The SCT is based on the partition of discontinuity planes in multiple planar sub-domains of various scale levels. In each sub- omain the higher-order modes are used for the accurate representation of the electromagnetic field local variations while low-order modes are used for coupling the various scale levels. The electromagnetic coupling between scales is modelled by a Scale Changing Network (SCN). As the calculation of SCN is mutually independent, the execution time can still be significantly reduced by parallelizing the computation. With the SCT, we can simulate large finite FSS, taking into account the exact interactions between elements, while addressing the problem of excessive computation time and memory

Les performances des outils numériques de simulation électromagnétique de structures complexes, i.e., échelles multiples, sont souvent limitées par les ressources informatiques disponibles. De nombreux méso-centres, fermes et grilles de calcul, se créent actuellement sur les campus universitaires. Utilisant ces ressources informatiques mutualisées, ce travail de thèse s'attache à évaluer les potentialités du concept de grille de calcul (Grid Computing) pour la simulation électromagnétique de structures multi-échelles. Les outils numériques de simulation électromagnétique n'étant pas conçus pour être utilisés dans un environnement distribué, la première étape consistait donc à les modifier afin de les déployer sur une grille de calcul. Une analyse approfondie a ensuite été menée pour évaluer les performances des outils de simulation ainsi déployés sur l'infrastructure informatique. Des nouvelles approches pour le calcul électromagnétique distribué avec ces outils sont présentées et validées. En particulier, ces approches permettent la réalisation de simulation électromagnétique de structures à échelles multiples en un temps record et avec une souplesse d'utilisation. / The numerical electromagnetic tools for complex structures simulation, i.e. multi-scale, are often limited by available computation resources. Nowadays, Grid computing has emerged as an important new field, based on shared distributed computing resources of Universities and laboratories. Using these shared resources, this study is focusing on grid computing potential for electromagnetic simulation of multi-scale structure. Since the numerical simulations tools codes are not initially written for distributed environment, the first step consists to adapt and deploy them in Grid computing environment. A performance study is then realized in order to evaluate the efficiency of execution on the test-bed infrastructure. New approaches for distributing the electromagnetic computations on the grid are presented and validated. These approaches allow a very remarkable simulation time reduction for multi-scale structures and friendly-user interfaces

Abstract Recent times have witnessed increasing availability of mobile technology-based products/services in developing regions such as Africa. However, the extant literature has not traditionally focused on understanding the adoption and use of these technologies by consumers in these parts of the world. This gap cannot be ignored and the need to investigate consumer intention to use mobile based-technology in this region is becoming paramount to their successful implementation. One such mobile-based technology is the M-pesa financial service. The current study merged appropriate theories that could predict consumer intention to use this M-pesa service in two African countries, Kenya and South Africa. First, the two countries were compared in an attempt to provide an explanation of why the launch of the M-pesa service has been more successful in Kenya than in South Africa. It then examined the effects of the Technology Acceptance Model variables (perceived usefulness and perceived ease of use), subjective norm from the Theory of Reasoned Action, self efficacy from the Social Cognitive Theory, and six dimensions of Switching Costs, on consumers intention to use M-pesa. To measure the study’s variables, validated scales from the IS literature, social psychology literature, and economics literature were identified and adopted. Data were collected using paper based survey instruments from individuals residing in low-income communities in Kenya (N=265) and South Africa (N=150), thus a total of 415 responses. The results indicate there are correlations between all variables and intention to use, however, only perceived usefulness, perceived ease of use, and subjective norms have a direct influence on intention to use M-pesa. The model explained 33.1% of the variance in intention to use M-pesa. The results suggest that while switching costs do not have a direct influence on intention to use, some of their effects are mediated in predicting intention to use. Thus, this study has paved the way for future testing and enhancement of the study’s model. The study’s contribution to theory and practice are also presented.

No description available.

124 p. / Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2012-12-20T18:07:25Z No. of bitstreams: 1 11.pdf: 1814278 bytes, checksum: 84a07cb25a6715f4ed4dfcf3ba591e8d (MD5) / Made available in DSpace on 2012-12-20T18:07:25Z (GMT). No. of bitstreams: 1 11.pdf: 1814278 bytes, checksum: 84a07cb25a6715f4ed4dfcf3ba591e8d (MD5) Previous issue date: 2012 / A formação científica em níveis de mestrado e doutorado está diretamente relacionada às possibilidades de maior empregabilidade e melhor remuneração dos indivíduos. Este aspecto constitui-se no fundamento primordial deste estudo, que busca avaliar a contribuição do PIBIC/FIOCRUZ-Bahia na formação de recursos humanos para o Sistema Nacional de Ciência, Tecnologia e Inovação em Saúde. Discute-se, também, a potencialidade da iniciação científica como ferramenta de inclusão e transformação social na cidade de Salvador-BA. A pesquisa foi realizada em três etapas e se iniciou com o levantamento de dados documentais na coordenação do PIBIC/FIOCRUZ-Bahia, quando foram identificados 338 indivíduos com ingresso no programa entre os anos de 1992 e 2009. Em seguida foram realizadas buscas aos seus currículos na Plataforma Lattes do CNPq, sendo identificados 286 registros, destes, 31,81% havia ingressado em programas de mestrado e 16,78% em cursos de doutorado, até dezembro de 2011. A terceira etapa foi responsável pela coleta de dados primários através do envio de questionário eletrônico aos egressos cadastrados na Plataforma Lattes. Nessa etapa foi obtido um retorno de 26,22% de respostas que forneceram informações utilizadas para descrever o perfil sócio demográfico dos egressos, bem como, a percepção dos exbolsistas sobre aspectos relacionados aos objetivos do Programa. Concluiu-se que os egressos do PIBIC/FIOCRUZ-Bahia alcançaram desempenho significativamente superior à média nacional do índice de ingresso em programas de pós-graduação stricto sensu em nível de mestrado e, sobretudo, em nível de doutorado. Os resultados da pesquisa, por outro lado, sugerem que a FIOCRUZ-Bahia ainda pode ampliar o acesso de egressos de escolas públicas do ensino médio, afrodescendentes, pessoas com deficiência física e moradores de bairros periféricos de Salvador-BA a uma educação emancipadora, viabilizada pela iniciação científica. / Salvador