Thesis (MPH.) -- University of Limpopo, 2021 / Background: The provision and success of Antiretroviral therapy (ART) depend on monitoring and evaluation of treatment programmes which should be assessed during regular patient follow-ups. The treatment of HIV infection can only be effective if patients are retained in care and programme monitoring is adequately undertaken to understand the effectiveness of the emerging treatment. The outcome of patients lost to follow-up (LTFU) has received relatively little attention and it is predicted that these patients may have stopped taking antiretroviral drugs, resulting in high morbidity and mortality. The provision of ART was introduced into South African public health facilities in 2003 and therefore, attention has shifted from the immediate need to get patients into care, to the long-term challenges of keeping patients in care and on treatment. The objective of the current study was to determine the trends at which HIV-positive patients become LTFU on the ART programme at Shiluvana Local Area’s six clinics in the Greater Tzaneen Sub-District, Limpopo Province, South Africa. Methods: A retrospective cohort study approach was used and data was collected from the database of patients who were LTFU from 2012 – 2017 in the electronic data management system of the District Health Information System. Data was collected from 1161 patients. Data analysis was done using SPSS version 25, in which categorical data was presented using frequencies and percentages and comparisons between groups was done using Chi-square test for categorical data, and Student’s t-test for continuous data. A p-value of <0.05 was considered statistically significant. Univariate regression analysis was done to determine the contributory factors to LTFU for a period of more than 3 months. Results: The mean age of the study population was 36.5 years old ranging from 16 years to 87 years old and the age distribution of people who were LTFU for ART showed a significant association (p = 0.001). The study participants’ distribution by gender revealed that majority were females at 71.4%. The study findings also revealed there was a statistically significance difference in health status of the study population and majority of the LTFU were in the younger age group. The CD4 count of LTFU patients showed a statistically significance difference and majority of the LTFU in patients with a CD4 count of less than 200 were in younger age group also. The TB/HIV co-infection in the study population showed a statistically significance difference and majority of LTFU in the study did not have TB/HIV co-infection. The WHO clinical HIV staging in the study population did not show a statistically significance difference. Marital status, TB/HIV co-infection and WHO clinical staging were found to be a strong predictor of LTFU of more than 3 months. Conclusion: The study findings bring with them a number of recommendations such as there is a need to have a standardised tracking method of patients who migrate to other health facilities for their ART treatment. This will provide more accurate information regarding LTFU levels and reduce the misclassification of patients. The age group which is affected by LTFU in all variables was in the 20 – 34 years’ age group. This is of great concern, as this is the age group who are economically active and should contribute to the future economy of the country. It is therefore recommended that a greater focus should be placed in this age group, with policies and programmes that bring them into ART and retain them there. Lastly, educational campaigns, in a form of pamphlets and posters to emphasize adherence to ART and the importance of remaining on ART within designated health facilities. In conclusion, patients should be retained in care for as long as possible to prevent the prevalence of the ARV resistant virus that can impact negatively on the ART programme. Keywords: Antiretroviral treatment. Human immunodeficiency virus, Loss to follow-up, socio-demographic.

Thesis (Ph. D. (Statistics)) -- University of Limpopo, 2019 / Refer to document / NRF-TDG

Philosophiae Doctor - PhD / Migration is an important topic, not only for researchers in South Africa, but also for policymakers and the media. It is an issue at the top of the national and international agenda. In the debate on migration and the literature, voices of migrants themselves remain mostly unheard. The public perceptions and policy-making are often based on fear, stereotypes and common myths rather than reality. In this study, the researcher aimed to examine the socio-economic integration challenges of highly-skilled Nigerian migrants and how they may help contribute their skills towards the socioeconomic development of South Africa to potentially inform the national migration policy, as well as future research. Methodologically, the researcher conducted a mixed-method study using an interpretive paradigm. Data were derived from 22 semi-structured interviews and six in-depth interviews. The study used a combination of purposive and snowballing sampling techniques, where semi-structured and in-depth interviews, as well as observations, were also carried out. Data gathered were analysed using thematic analysis.

Ce travail est dédié à l'étude des mécanismes clés contrôlant l'écoulement linéaire et non-linéaire ainsi que l'état de dispersion des polymères fondus chargés avec des particules submicrométriques. La compréhension fondamentale est ensuite appliquée au procédé de moulage par injection céramique lors duquel un mélange-maître (i.e., une formulation complexe à base de polymères et avec un haut taux de charges de particules de céramique) est injecté dans un moule puis délianté et fritté. Un premier chapitre présente les caractéristiques principales du procédé, l'état de l'art de la compréhension des mécanismes concernés, ainsi que plus généralement, les forces d'interaction en jeu dans les polymères chargés. Ensuite, l'étude se focalise sur le polyéthylène chargé en zircone. Tout d'abord, le rôle de l'interface charge-matrice dans les propriétés rhéologiques et morphologiques est discuté. Il est montré qu'elles sont fortement influencées par la compatibilité de la charge avec la matrice. Une méthode expérimentale est développée pour ajuster la qualité de l'interface. En particulier, l'acide stéarique est déterminé comme étant le surfactant le plus efficace. La cinétique d'hydrophobisation des particules induite par l'estérification est analysée. Par la suite, les mécanismes de dispersion dans les polymères chargés sont explorés. Par exemple, il est conclu que l'acide stéarique et l'extrudeuse à fort cisaillement promeuvent la rupture et l'érosion des agglomérats. Leurs effets sur le comportement rhéologique (i.e., seuil de percolation, contrainte d'écoulement et modulus élastique dynamique) sont discutés. Enfin, la stabilité des polymères chargés, i.e., leur tendence à la floculation et à la ségrégation matrice-charge, est évaluée au repos et à haut taux de cisaillement. Deux méthodes expérimentales sont développées pour cette étude plus appliquée. Le rôle crucial de l'état de dispersion est notamment mis en avant / This work aims to investigate the relevant mechanisms controlling the linear and non-linear flow behaviors and dispersion state of molten polymers filled with submicrometer particles. The fundamental understanding is then applied to the Ceramic Injection Molding process, during which a feedstock (i.e., a complex polymer based formulation, highly filled with ceramic particles) is injected into a mold, debinded and sintered. A first chapter presents the key features of the process, a state of the art of the understanding of the involved mechanisms and more generally the interplaying interaction forces in filled polymers. Then, the study focuses on zirconia filled polyethylene. Firstly, the role of the filler-matrix interface in the rheological and morphological properties is discussed. It is shown that they are strongly influenced by the compatibility of the filler with the matrix. An experimental method is developed to adjust the interface quality. In particular, stearic acid is determined to be the most efficient surfactant. The kinetics of particles hydrophobization induced by the esterification is analyzed. Then, the dispersion mechanisms in filled polymers are explored. For instance, it is concluded that stearic acid and the high shear extruder promote the rupture and erosion of agglomerates. Their effects on the rheological behavior (i.e., percolation threshold, yield stress and dynamic storage modulus) are discussed. Finally, the stability of filled polymers, i.e., tendency to flocculation and filler-matrix segregation, is evaluated at rest and under high shear rates. Two experimental methods are developed for this more applied study. The crucial role of the dispersion state is for instance highlighted

La synthèse d'ouverture est une technique interférométrique similaire à la synthèse par rotation de la terre utilisée en radioastronomie où les signaux reçus par une paire de petites antennes sont traités de telle manière à synthétiser une seule grande antenne. Le concept de synthèse d'ouverture a été réadapté pour l'observation de la terre dans le cas de la télédétection de sources étendues de température. L'utilisation de cette technique pour l'observation de la terre a permis de contourner les limitations sur la taille d'antenne en télédétection passive. La fonction de corrélation, ou de visibilité, obtenue en inter-corrélant les signaux reçus par les an- tennes d'un système interférométrique employant une synthèse d'ouverture est définie comme étant la transformée de Fourier de la carte des températures de bril lance de la scène observée. Cette relation est connue sous le nom du théorème de Van Cittert-Zernike pour des observateurs en repos par rapport aux sources de température. La forme classique de ce théorème a été dérivée en inter-corrélant les échantillons temporels instantanés du champ électrique mesurés par différentes antennes. Un nouveau concept basé une interférométrie spatio-temporelle passive a été proposé comme étant la nouvelle génération qui succédera à la mission SMOS (Soil Moisture and Ocean Salinity) opérant dans l'espace depuis Novembre 2009. Celui-ci a pour objectif principal l'amélioration de la résolution spatiale à des ordres pouvant répondre aux applications hydrologiques à l'échelle locale où des résolutions kilométriques sont exigées. Ce concept interférométrique se base sur l'idée d'intégrer le déplacement de l'observateur (l'antenne) et ainsi la variable temps dans le calcul de la fonction de corrélation. Ceci engendre la création de nouvelles lignes de base virtuelles entre les positions des antennes à des instants différents, en plus des lignes de base physiques formées entres les positions des antennes instantanées. L'étude de ce concept de corrélation a malheureusement démontré la suppression exacte de l'information additionnelle due aux lignes de base virtuelles par le décalage Doppler induit par le déplacement. Une seconde étude du concept d'interférométrie spatio-temporelle combinée à une nouvelle procé- dure d'imagerie par corrélation dans l'espace fréquentiel, accomplie en inter-corrélant les spectres fréquentiels des champs électriques mesurés par une paire d'antennes séparées d'une distance Δr à bord d'un satellite à une hauteur h, a démontré l'obtention d'une information en 2D en températures de brillance de la scène observée. En plus, le développement théorique de la fonction de corrélation a mis en évidence une relation liant les visibilités aux températures de brillance par l'intermédiaire d'un noyau hautement oscillatoire. L'élément nouveau apporté par la corrélation dans l'espace fréquentiel consiste à exploiter l'informati- on de corrélation acquise par les antennes du satellite pour des fréquences présentant de petites dif- férences et pas seulement l'auto-corrélation. Cette propriété permet une reconstruction en 2D des températures de brillance avec seulement deux antennes / Aperture synthesis is an interferometric technique similar to Earth rotation synthesis employed in radio astronomy in which the signals received by a pair of small antennas are processed in a way to synthesize a single large antenna. The aperture synthetic concept used in radioastronomy was readapted to Earth remote sensing for large thermal sources. Thanks to this technique, limitations on antenna size in passive microwave remote sensing have been overcome. The correlation, or visibility, function obtained by cross-correlating the signals received by the antennas of an interferometric system using aperture synthesis is linked to the brightness temperature map of the observed scene by means of a Fourier-transform law. This is know as the standard form of the Van Cittert-Zernike theorem for fixed observers with respect to sources of temperature. This stan- dard formulation is derived by cross-correlating the instantaneous temporal components of the measured electric fields by different antennas. A new concept based on a passive spatio-temporal interferometry was proposed as the new generation to follow the well-known SMOS (Soil Moisture and Ocean Salinity) mission successfully operating since November 2, 2009. The aim of the proposed concept is a jump in the current achieved geometric resolution to orders capable of meeting the stringent users' needs for the study of hydrological applications in the local scale where sub-kilometric resolutions are required. This interferometric concept is based on the idea of integrating the displacement of the observer (satellite's antenna), and hence the time variable, in the calculation of the correlation function, which yields the creation of virtual baselines between the positions of antennas at different instants, in addition to the physical ones formed between the instantaneous antennas' spatial positions. Sadly, the additional information due to the virtual baseline was shown to be exactly canceled by the induced Doppler shift due to the observer's motion. We show furthermore that when using the aforementioned spatio-temporal interferometric system combined with a revolutionary Fourier Correlation Imaging (FouCoIm) procedure, consisting in cross-correlating, at slightly different frequencies, the Fourier components of the fluctuations of the re- ceived electric fields by a pair of antennas separated by a distance Δr on board of a satellite flying at height h, the 2D position-dependent brightness temperature can be reconstructed. Besides, the analytical derivation of the correlation function gives rise to a relationship linking the measured cor- relations to the position-dependent brightness temperatures by means of a Highly Oscillatory Integral (HOI) kernel. Interestingly, the analytical study of the HOI kernel showed the remarkable property that a corre- lation between both antenna-signals remains within a small frequency interval (different frequencies) outside the simple auto-correlation (same frequency). As a matter of fact, while existing systems had, until now, only considered the simple 1D information contained in the auto-correlation, it appears that the resulting correlation function from this concept bears a 2D information for the measurement of the position-dependent brightness temperature. Based on this, one is capable of reconstructing 2D bright- ness temperatures starting from a simple 1D geometry (two antennas arranged perpendicularly to the flight direction)

Indiana University-Purdue University Indianapolis (IUPUI) / There are various types of power electronic converters available in recent days. In some applications (e.g. PC power supply), it is required to supply more than one load from a single power supply. One of the main challenges while designing a power converter is to increase its e ciency especially when the number of power switches employed is relatively large. While several loads are supplied from a single source, if the power loss in the switches cannot be reduced, then the expected utilization of using a single source is not very feasible. To reduce the loss and increase e ciency, the thesis presents a novel design with reduced number of switches. The scope of this thesis is not limited to the dc-dc converter only, the converter to supply three phase ac loads from a single dc source is also presented. This discussion includes an improved fault tolerant configuration of the inverter part. The generated waveforms from the simulations are included as a demonstration of satisfactory results.

Thermosets show excellent mechanical properties and chemical resistance (for most automotive fluids) even at high temperatures up to 300 °C. Furthermore they can be highly efficient processed by injection molding. So they should be particularly suited for e.g. under the bonnet applications. However, the reality shows that thermosets are, except fiber reinforced composites, heavily underrepresented in technical applications. E.g. thermosetting components only account 0,2 % to a vehicle’s weight. Therefore reasons can be found in limited knowledge, e.g. relating mold filling behavior. The objective of the study is to analyze the influence of the mold filling behavior during injection molding of highly filled phenolic compounds on mechanical properties. Injection molding filling studies, mechanical testing and optical microscopy were done while varying mold geometry (injection gate and cavity height), mold temperature and injection rate during injection molding a highly filled phenolic compound. It was found that the mold filling behavior varies with altered injection molding parameters as well as the mold geometry. In consequence of this the mechanical properties change according to the resulting reinforcement orientation. The results can help to improve part and mold design for optimal load transmission.

Analysis of rhesus monkey alphoid DNA suggests that it arose by tandem duplication of an ancestral monomer unit followed by independent variation within two adjacent monomers (one becoming more divergent than the other) before their amplification as a dimer unit to produce tandem arrays. The rhesus monkey alphoid DNA is a tandemly repeated, 343-bp dimer; the consensus dimer is over 98% homologous to the alphoid dimers reported for baboon and bonnet monkey, 81% homologous to the African green monkey alpha monomer, and less than 70% homologous to the more divergent human alphoid DNAs. The consensus dimer consists of two wings (I and II, 172 and 171 bp, respectively) that are only 70% homologous to each other, but share seven regions of exact homology. These same regions are highly conserved among the consensus sequences of the other cercopithecid alphoid DNAs. The three alpha-protein binding sites reported for African green monkey alpha DNA by F. Strauss and A. Varshavsky (Cell 37: 889-901, 1984) occur in wings I and II, but with one site altered in wing I. Two cloned dimer segments are 98% homologous to the consensus, each containing 8 single-base-pair differences within the 343-bp segment. Surprisingly, 37% of these differences occur in regions that are evolutionarily conserved in the alphoid consensus sequences, including the alpha-protein binding sites. Sequence variation in this highly repetitive DNA family may produce unique nucleosomal architectures for different members of an alphoid array. These unique architectures may modulate the evolution of these repetitive DNAs and may produce unique centromeric characteristics in primate chromosomes.

Masters of Commerce / Highly enriched uranium (HEU) is one of the most dangerous materials in the world, because it is a key ingredient in making a nuclear bomb. If a terrorist organisation can get HEU, it would be close to making a nuclear bomb. After South Africa disarmed its nuclear weapons, it kept HEU that was extracted from the nuclear bombs. The US tried to persuade South Africa to blend down its HEU into low enriched uranium (LEU) or give it up for safekeeping. However, South Africa refused to give it up. After a breach at Pelindaba, a national key point facility where South Africa stores its HEU, the US intensified its efforts to pressure South Africa to give its HEU up. It even promised incentives to South Africa should they agree to give it up, but South Africa refused. The US used the nuclear terrorism narrative to justify its initiative to eliminate vulnerable materials in the world. However, South Africa is yet to be swayed. This is odd since South Africa's refusal can negatively affect its credentials as a nuclear non-proliferation and disarmament champion and its image as a norm entrepreneur. The objective of the study was to understand the role played by HEU in South Africa's nuclear diplomacy. It was to explore HEU as a factor in the state's nuclear diplomacy and to understand the power of having HEU in nuclear negotiations, as well as what SA intends to do with its HEU. The study is framed theoretically by drawing on foreign policy theory, namely middle-power theory, and revisionism. It juxtaposed middle power, reformist, and revisionist positions with status quo foreign policy to analyse the role of HEU in South Africa's nuclear diplomacy. As a middle power with a moral high ground, South Africa hoped that it can affect change in the nuclear regime. However, when this did not occur its foreign policy shifted to a revisionist character that is discontent with the status quo in the nuclear regime. SA is dissatisfied with the current nuclear order and wants it revised towards liberal values such as equality and non-discrimination. It views the current nuclear order as nuclear apartheid. Therefore, South Africa uses HEU as leverage against nuclear weapon states in nuclear diplomacy. It is using HEU as an act of defiance against nuclear weapon states (such as the US) that are yet to disarm their nuclear weapons.

According to several studies, it is difficult for highly educated immigrants to find a job that match their education. A large number of them are forced to work in low-skilled jobs to cope with their daily lives. In this study, I will examine highly educated immigrants experience of their situation in the Swedish labor market. The study aims to examine the obstacles and opportunities that highly educated immigrants face in the labor market. The study is based on internal opinions where personal experiences and reflections of different participants were analyzed. The focus of the study is how six educated immigrants describe their situation in the Swedish labor market. This paperaims to increase knowledge about highly educated immigrants' conditions, expectations, obstacles and opportunities in the Swedish labor market. The results of the interviews with the participants were analyzed using key concepts from the two sociologists Erving Goffman and Pierre Bourdieu. The results show that the lack of a valuable social network, loss of symbolic and cultural capital that the participants had in their home country, plus the various demands from the employer, which is a major focus on the Swedish language, makes it difficult for academic immigrants to find a qualified job. respond to their education. / Enligt flera studier är det svårt för högutbildade invandrare att hitta ett jobb som möter deras utbildning. Ett stort antal högutbildade invandrare tvingas arbeta i lågkvalificerade jobb för att klara av sitt dagliga liv. I den här studie kommer jag att undersöka högutbildade invandrares upplevelser av sin situation på den svenska arbetsmarknaden. Studien syftar till att undersöka de hinder och möjligheter som högutbildade invandrare står inför på arbetsmarknaden. Studien bygger på interna åsikter där personliga erfarenheter och reflektioner av olika deltagare analyseras. Studiens fokus ligger på hur sex högutbildade invandrare beskriver sin situation på den svenska arbetsmarknaden. Syftet är att fördjupa förståelsen kring faktorer som påverkar högutbildade invandrares inträde och integration på den svenska arbetsmarknaden. Resultaten av intervjuerna med deltagarna analyserades med hjälp av centrala begrepp från de två sociologerna Erving Goffman och Pierre Bourdieu. Mitt resultat visar att bristen på ett värdefullt socialt nätverk, förlust av symboliskt och kulturellt kapital som deltagarna hade i hemlandet, plus de olika kraven från arbetsgivaren som ligger stor fokus på det svenska språket gör det svårt för högutbildade invandrare att hitta ett kvalificerat jobb som bemöter deras utbildning.