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A system for high strain rate interruptible tensile tests
No full textThe Split Hopkinson Pressure Bar (SHPB) is a widely used piece of equipment used for measuring a material's response to high strain rates. High strain rate data is critical for exhaustive characterisation, due to the sensitivity of materials to the rate at which they are strained. The principle limitation of conventional SHPB is that there is limited control of the ultimate deformation of specimens, because specimens are rarely recoverable after having undergone a single loading event. For this reason, microstructural investigations on SHPB specimens offer limited value, as the specimen was loaded repeatedly. In the MSc, a tensile SHPB (TSHB) was designed with momentum trapping to conduct interruptible tests on specimens. This configuration makes use of tandem momentum traps, allowing for the system to be fully trapped without the need for precisely preset gaps, or tight control over striker speed. A pull-off design of tubular tensile striker was used alongside the tandem momentum trapping, in a novel configuration allowing the input bar to remain supported over its entire length. The fir-tree design of dynamic tensile specimen fixture was utilised. Thorough preliminary measurements of the wave propagation properties of the hardware are taken. Strain gauge calibration tests were then conducted, followed by a rigorous commissioning process. This involved fine-tuning trap impedances and verification of the complex critical subsystems. As the commissioning process progressed, emergent flaws were rectified, and a standard operating procedure was established to ensure the reliable performance of said subsystems. The operation of the TSHB was demonstrated by a series of experiments on DOMEX 550 specimens. The recorded loading history is compared to the measured length of recovered specimens as verification of the interruptibility of tests using this apparatus. These specimens are also compared to those tested under the same conditions, but without the interruption, further demonstrating the effectiveness of the developed system
Quantitative measurement of spatial accessibility to locations both in urban and peri-urban environments
No full textLast-mile delivery in the context of transportation and supply chain refers to the final stage of the product delivery process. The last mile is often the most challenging part of transporting packages to their final destinations. It is essential to have easily accessible infrastructure so that packages can be collected with less travel distances and transportation costs. Accessibility is an important aspect of transportation planning. It is used to measure the spatial separation of human activities such as commerce, employment and quality of life. Accessibility reflects the extent of interaction between an area's land use development and transportation system. The aim of the research is to evaluate accessibility using Geographic Information System (GIS)-based techniques, to measure coverage and associated potential market for existing pick-up points, and to suggest modifications to improve accessibility. Spatial analyses, which deal with service location modelling, are carried out using Flowmap software. The analyses include; proximity counts analysis, and catchment area analysis. Literature reviewed discusses the components of accessibility, indicators of accessibility, and GIS-based accessibility modelling. The common measurement of accessibility (gravity-based) used in trip distribution modelling is explained. Gauteng province is used as a study area. Various methods used to analyse the raw data to prepare it for use in modelling are discussed. The cumulative opportunity index, also known as the proximity count, which is an accessibility measure, is used to identify potential customers within a set distance. The user-defined distances in this case are 1610m (1-mile) and 3220m (2-miles). Without considering competition, a proximity count provides an indication of a potential market. Catchment area analyses were also performed. The technique searches within the set distance and allocates origins to the nearest destinations. Trend surface maps (suitability maps) were produced, and they showed the locations of potential populations that the parcel pickup points are not available. The maximum number of customers per site and the pickup points needed to cover an area were computed. In densely populated areas where Pargo service is already in high demand, growing the number of pickup facilities would improve accessibility. Future research directions suggested include analysis of the study areas based on land-use, assessing the accessibility of pickup facilities in densely populated areas and extending the scope beyond Gauteng province
Personal finance: a statistical analysis of the habits and behaviours of the South African consumer
Get PDFUnderstanding consumer spending behavior and the efficacy of budget setting is crucial in managing personal finances. This dissertation employs clustering methodologies and statistical models to explore the intricate dynamics of financial habits and their relationship with budget establishment using longitudinal spending data from the 22seven platform. The initial chapters delve into the analysis of consumer spending behavior through various clustering techniques, unveiling fundamental drivers of spending patterns. While highlighting the role of spending control in distinguishing consumer clusters, the study emphasizes its correlation with wealth creation potential. Subsequently, the investigation into the impact of budget setting on expenditure habits reveals compelling evidence. Individuals who set a budget exhibited a significant reduction in spending, indicating an average decrease of approximately 38% compared to non-budget setters. However, limitations in observational data analysis, including incomplete financial account linkage and potential sample bias, caution against drawing absolute conclusions. This dissertation underscores the complexity of consumer financial decision-making, calling for continued exploration and refinement of methodologies to better grasp the nuanced interplay between budget setting and expenditure patterns. While providing valuable insights, this study serves as a stepping stone for future research, encouraging a deeper understanding of effective spending control, the balance between consumption and savings, and the broader efficacy of budgeting in managing overspend
Statistical modelling to determine the influence of vaccine dose and prior Mycobacterium tuberculosis exposure on antigen-specific T cell responses
Get PDFThis dissertation investigates the effects of two subunit vaccines H1:IC31 and H56:IC31 as well as prior M.tb sensitization on the immune responses of three cohorts of South African adolescents and adults. The primary outcomes are frequencies of antigen-specific CD4 T cells expressing different combinations of immunological markers over three time points. Two M.tb antigens are investigated: Ag85B and ESAT-6. The dissertation compares the results produced by the standard procedures that would typically be employed in the immunology research community to investigate these aims with the results produced by employing a mixed effect modelling approach. Not only is it of interest to investigate whether the results agree, but also to investigate the difference in inference that one can make and whether the mixed effect modelling approach is able to provide greater insight into the data. Methods typically employed by the immunology community that are used in this thesis are non-parametric pair-wise tests and the data analysis pipelines mixture models for single-cell assays (MIMOSA) and combinatorial polyfunctionality analysis of single cells (COMPASS). For the mixed effect modelling approach, generalized linear mixed effect models with various hierarchical structures as well as latent variable models are employed. Results suggest that 5 μg of the vaccine induces the strongest immune response. The mixed effect modelling approach showed good potential in terms of depth of analysis and ease of interpretation, however many model assumptions were violated making inference difficult. The standard approaches where much more cumbersome to implement and interpret and resulted in significant multiple testing concerns
An exploration of parents' and guardians' perspectives on facilitators and barriers to menstrual cup usage amongst adolescent girls in De Doorns, Cape Winelands
Get PDFAdolescent girls in low-income communities in South Africa often cannot afford to buy disposable sanitary pads. Though menstrual cups are considered relatively cost-effective, uptake in South Africa remains low. This qualitative study investigated parents' and guardians' perspectives on factors that enable or hinder menstrual cup use among adolescent girls. Two focus group discussions and 10 individual interviews were conducted with study participants in De Doorns, a farming community in Cape Winelands. Data were uploaded onto NVivo 14 and analysed thematically. The study findings indicate that parents and guardians viewed menstrual cups as a viable option for upholding adolescent girls' dignity and alleviating the financial burden of purchasing menstrual products. This emerged as a supportive factor for adolescent girls' adoption. Further, parents and guardians believed that adolescent girls are a diverse group with varying needs, emphasising the importance of promoting their autonomy in choosing menstrual products. However, they encountered various challenges in adapting to menstrual cups, which left them feeling ill equipped to provide support to their adolescent girls. Concerns related to menstrual cup sizing and fears about potential impacts on virginity were common issues that contributed to their hesitation in endorsing usage among adolescent girls. To facilitate adoption, manufacturers of menstrual cups and community organisations involved in supporting the use of the same should consider parents' and guardians' perspectives, bearing in mind their pivotal roles as caregivers of adolescent girls. Further, there is a need for further knowledge dissemination to increase community buy-in
The heterogeneous impacts of energy type and metering systems on household welfare: insights from Ghana and South Africa
Get PDFThis thesis addresses the multifaceted challenges associated with energy delivery and usage in emerging economies, focusing on their impacts on household welfare. It examines the differential effects of electricity and other primary energy sources on household enterprise income in Ghana, highlighting the significant role of energy inputs in enterprise development. Additionally, the study investigates the relationship between prepaid electricity metering and food insecurity in South Africa, revealing how prepayment systems can exacerbate hunger due to their advance payment requirement. Furthermore, the research explores the link between prepaid electricity metering and energy poverty, showing that such systems can increase the likelihood of households becoming energy-poor and resorting to unclean energy sources. Through comprehensive empirical analyses presented in three substantive papers in Chapters Two to Four, this thesis provides critical insights into the policy implications of the Heterogeneous Impacts of Energy Type and Metering Systems on Household Welfare, advocating for targeted government interventions to alleviate food and energy poverty and promote sustainable energy use. Chapter Two presents productive electricity use by non-farm enterprises in Ghana. Energy inputs such as electricity and fuel are essential drivers of enterprise development. The research employs the Ghana Living Standard Survey (GLSS7) data to examine the importance of electricity usage on household enterprise income. This study further shows the relevance of fuel expenditure and other firm characteristics in the enterprise production process. The Lewbel IV method was the main estimation approach used in the study, with the standard Instrumental Variable (IV) results providing a foundational estimation. Both methods showed positive effects of electricity and fuel expenditure on enterprise performance. However, the test for differences between the coefficients of electricity and fuel remained insignificant, highlighting that both energy inputs are equally important. The choice between them should consider other external factors. Furthermore, heterogeneity results based on firm size, type, location, and gender revealed specific differences when considering particular inputs, but these differential impacts were statistically insignificant. Our results have significant policy implications and advance the need for enhanced government electricity programs. Additionally, the government electricity expansion program should be target-specific if the goal is to facilitate household welfare through the productive use of electricity and promote modern fuel supply to improve household enterprise income in Ghana. This chapter's academic contribution includes decomposing the composite energy input in a household enterprise income model into electricity and other primary sources of energy (referred to as fuel) to explore energy's differential and heterogeneous impacts on household enterprise income. Chapter Three discusses food insecurity, a long-time issue in South Africa, with over 12% (7.26 million) of its population suffering from hunger. Food insecurity in South Africa can be attributed to multiple factors, including income, employment, and access to food. However, prepayment systems could also explain food insecurity in the country as they require households to pay in advance, potentially reducing savings. This research investigates the differential impact of electricity prepayment systems and competing policy instruments on food insecurity. Applying robust techniques such as propensity score matching to the General Household Survey 2020 from South Africa, the findings show that households that use prepaid electricity meters have a higher probability of experiencing hunger. Specifically, using prepaid meters increases hunger in families and among adults and children by 3.9%, 4.7%, and 4.4%, respectively. However, hunger marginally decreases when households receive social interventions with prepaid meters. The study further observed multiple burdens of chronic diseases mediating the relationship between using prepaid electricity meters and hunger. Therefore, the policy implications of the results suggest reviewing prepaid metering and subsidy schemes for low-income households. Additionally, the study suggests that providing food assistance programs or subsidies may prove vital in directly addressing hunger in these vulnerable households. This chapter makes a significant academic contribution by pioneering the empirical regression analysis of the heterogeneous relationship between, among other factors, the use of prepaid electricity metering and food insecurity. Chapter Four investigates the relationship between energy poverty and prepayment systems. Energy poverty is a major global issue and has implications for the welfare of individuals and society. The main drivers and barometers in measuring this phenomenon have varied across specific indicators and country-specific case studies. An often underexplained cause is the payment systems constraining electricity consumption in multiple fuel uses, resulting in fuel switching. We use the General Household Survey data of South Africa to explain the impact of prepaid payment systems on energy poverty. Applying fractional probit regression and other robustness methods, the results show that using prepaid meters increases energy poverty between 0.03 and 0.06 percentage points. Using Propensity Score Matching (PSM) to address endogeneity and enable impact analysis through quasi-experimental methods, the study found that households using prepaid meters had a 3.35% higher likelihood of being energy-poor than those using postpaid meters. The study further revealed that households become energy-deprived by switching to unclean energy sources for cooking and heating when given prepaid meters. Specifically, prepaid meters increased biomass for cooking by 5.7%, space heating by 10.9%, and room heating by 4.3%. The results also showed that vulnerable groups or poor South Africans suffer most from energy poverty using prepaid meters. Joint use of prepaid meters and Free Basic Electricity (FBE) could reduce energy poverty. Additionally, the study highlights that the combination of the Reconstruction and Development Programme (RDP) housing scheme with prepaid meters is an effective pro-poor policy in reducing energy poverty. The study's policy implications suggest increased energy subsidies and targeted policy interventions to mitigate energy poverty. This chapter makes a significant academic contribution by pioneering the empirical regression analysis of the heterogeneous relationship between, among other factors, the use of prepaid electricity metering and energy poverty. This study emphasises the imperative for governments to prioritise cleaner energy investments, particularly in electricity, due to its comparable impact on fuel energy but with enhanced environmental sustainability. By highlighting the lack of a significant difference in the effect of electricity and fuel energy, the research underscores the ecological advantages of electricity, urging a shift away from environmentally unfriendly fuel reliance. Additionally, the study makes a novel contribution by extending the known link between payment systems and food insecurity to electricity payment systems, shedding light on an overlooked aspect in the existing literature. Furthermore, it reveals the potential impact of payment systems on food insecurity and advocates for a comprehensive approach that addresses this economic issue for adults and children, considering safeguards not previously explored in policy solutions. The exploration of the role of prepayment technology in explaining energy poverty adds another layer to the study's contributions. Moreover, the emphasis on housing policy and energy subsidies emerges as a significant revelation, serving as a policy guide for Sub-Saharan countries and developing states aiming to enhance household welfare through well-structured policies and clean energy development, aligning with the global campaign against climate change mitigation
Bridging local and external knowledge for disaster risk management planning: The perceived benefit of participatory 3D modelling in Umgungundlovu District Municipality, South Africa
Get PDFThere are natural hazards affecting communities all over the world. These events also take place in South Africa. South African disaster management legislation emphasises the indigenous knowledge of people who are most affected when hazards turn into disaster. Participatory GIS in the form of activities building and using three-dimensional models (P3DM) has been used internationally to enhance community engagement and to ensure better information exchange between people who live in the area and the disaster officials and consultants who currently inform decisions. P3DM was introduced in uMgungundlovu District Municipality through a progressive case study methodology with workshops in four locations introduced by municipal officials. This research focused on the officials' perceived value of using P3DM activities to enhance their standard disaster risk management practices. Lightning, fires, earthquakes and strong winds are all natural hazards experienced by people living in communities. Over a period of several generations, these people have developed knowledge local to their area that is relevant in planning to reduce the risk of disasters in their area. The disaster risk management legislation governing this planning requires the sharing of local knowledge. The implementation of the legislation and the sharing of local knowledge are challenging. Participatory three-dimensional modelling (P3DM) has been used in the Global South as a novel method to promote knowledge sharing in this context. Although this method is commonly used elsewhere in the Global South, it has not yet been used or introduced in South Africa. Through a progressive case study in four locations in uMgungundlovu District Municipality, P3DM was introduced to stakeholders in disaster planning. There was an opportunity to analyse and assess the perceived value of P3DM to stakeholders at each location. Observational case study methods including semi-structured interviews allowed data collection and analysis to assess the perceived value of P3DM. P3DM was found to add value to stakeholders already familiar with incorporating local knowledge in disaster planning. Officials and community members attending workshops where P3DM activities were introduced recognized that building models and adding LIK to the models facilitates knowledge sharing
Injurie in gymnastics: The knowledge, attitudes, and practices of South African gymnastics coaches
Get PDFOver the last few decades, athlete participation in gymnastics has increased. Injuries occur at all levels of participation in gymnastics from recreational to elite levels. Elite gymnasts may commence training from as early as five years of age and may train consistently for between 20 to 40 hours per week over a full calendar year. Gymnasts are at high risk of injury, and this is associated with longer practice times and increased complexity of routines. Gymnastics coaches are involved in the selection of training programmes for the athlete that may result in both an improvement in athletic performance and decrease in injury risk. Coaches are also typically responsible for promoting injury prevention behaviours in athletes. The aim of this dissertation was to describe the knowledge, attitudes and practices (KAP) of South African-based gymnastics coaches regarding injuries and injury prevention in the sport
Systematic Kaposi-Sarcoma Herpesvirus (KSHV) genome analysis from a South African HIV- and KSHV-positive patient cohort
No full textKaposi sarcoma herpesvirus (KSHV) is an oncogenic virus and the etiological agent of Kaposi's sarcoma, the most common AIDS-associated cancer. KSHV infection occurs primarily in Sub-Saharan Africa (SSA) where it is also associated with other pathologies such as Multicentric Castleman's Disease, Primary Effusion Lymphoma and KSHV-associated inflammatory cytokine syndrome, which also occur primarily with HIV co-infection. IN SSA most individuals ac-quire KSHV infection during childhood where it remains undetected until later in life when the burden of HIV takes its effect on the immune system. There are 6 predominant KSHV subtypes world-wide, namely A, B, C, D, E and F which are determined by the highly variable K1 region of the KSHV genome. Sequencing and characterizing the circulating subtypes in a specific geographical region assist in tracking evolutionary changes as well as malignant outcomes associated with different subtypes. The aim of this study was to determine the circulating KSHV subtypes in the Western Cape region of South Africa. A total of 57 DNA samples isolated from peripheral blood of confirmed HIV/KSHV co-infected patients were selected according to KSHV viral load (VL) (> 5 copies/10 μL) and volume (> 5 μL). Of these, 20 were successfully Sanger sequenced to determine K1 subtype. Additionally, 9 samples met the criteria for whole-genome sequencing using Next Generation Sequencing (NGS). This study produced 29 K1 sequences (20 via Sanger and 9 via NGS) of which 26 were of the A subtype, specifically A5, and the remaining 3 were of the B subtype, namely B2. These results are consistent with previous studies from the same region where a trend of high A5 and B subtypes in AIDS-KS patients were reported. ORF-K15 is another variable and lytic gene associated with KSHV subtyping (alleles M, N and P). Sequencing results of the K15 gene, revealed two P subtypes, three M subtypes and four N subtypes in our samples. These novel results from the Western Cape of South Africa point towards an interesting distribution of subtypes contributing to previous reports of K15 P and M subtypes being the most prevalent in Africa. There are limited whole-genome sequences available for South Africa, therefore these sequences provide a significant contribution to the pool of sequences available for this region
Assisted Partner Notification for HIV: a qualitative study of providers and female patients perspectives and experiences of assisted partner notification in Cape Town, South Africa
Get PDFBackground Assisted partner notification (APN) is a partner notification approach where trained providers assist individuals newly diagnosed with HIV to notify their partners and then link these partners to testing and treatment services. APN has been found to be more effective at increasing HIVtesting and linkage to care rates than passive referral, where HIV-positive individuals notify partners themselves. In 2016, the WHO published official APN guidelines recommending APN for HIV. However, various factors have influenced the implementation of APN such as human rights concerns and ethical dilemmas, fear of social harm, intimate partner violence or relationship dissolution, and social and cultural factors such as gender. In South Africa, there are no specific guidelines or policies informing the implementation of APN and we are unsure about how implementation unfolds. This study sought to better understand APN by exploring patients' and providers' experiences and perceptions of APN, taking into consideration different factors that shape partner notification documented in local and international literature. The influence of religion and faith and the involvement of faith-based organisations, as well as the impact of the COVID-19 pandemic on APN for HIV also feature in this study. Methods Qualitative research methods were used in this study. Thirty-four individual, semi-structured interviews with providers (n=10), female patients (n=12) and key informants (n=12) were conducted between March 2021 and February 2022. A diary study using the WhatsApp social media platform and fieldwork journals served to triangulate the interview data collected. Data analysis involved thematic analysis incorporating an intersectional lens. The data were transcribed, then coded using NVivo software. The codes were subsequently organised into overarching themes and sub-themes. Ethics approval was obtained from the Human Research Ethics Council at the University of Cape Town (HREC Ref: 840/2020) and the City of Cape Town (Ref: 28185). Results The study found that while there are no official APN guidelines in this setting, an unofficial APN process unfolded, nevertheless. Patients' views of APN were varied; some felt providerassistance for partner notification was not required at all, others felt it was required if their attempts to notify partners failed and a few saw it as a form of interference in their personal and sexual lives. Relationship type and pre-marital HIV-testing were found to influence patients' decision-making around APN engagement. Insider and outsider narratives emerged revealing the complexities involved in making decisions about who to include or exclude during APN. Providers were found to play several roles during APN: education, facilitation/mediation, and protection. Providers also expressed how their relationships with patients could considerably influence whether patients would notify partners. Factors influencing providers' willingness to offer assistance during APN included fears of causing negative events in patients' relationships and partners not maintaining confidentiality after being notified. Providers employed various trust-building strategies to navigate these concerns. Power imbalances and gendered assumptions of health service use influenced APN substantially. Women took on a central role in partner notification due to greater healthcare involvement and societal beliefs around healthcare practices. Female patients often communicated HIV matters with female providers, revealing that caregiving roles were mostly played by women in APN. Indirect and social media based-partner notification as well as 'collusion testing', where providers and patients colluded to bring partners to clinics for testing, emerged as strategies to fulfil rights and responsibilities related to APN. While some of these effectively linked sexual partners to testing and care, it raised ethical concerns about partners' rights. Provision of APN was also found to be different between non-faith-based and faith-based providers who offered either biomedical care or a form of 'umbrella care' which incorporated biomedical and psychosocial and emotional care, respectively. The moralisation of HIV and certain sexual behaviours using religion as a moral framework imposed a sense of obligation to engage in APN. Participants were ambivalent about the involvement of church elders or pastors in APN, seeing providers as being more appropriate due to their HIV-related training. However, many acknowledged the importance of religious support in motivating them to notify partners and finding hope and resilience, if diagnosed with HIV. Conclusion This study highlights the need for clear and context-specific guidelines in implementing APN. The absence of such guidelines resulted in uncertainty among both patients and providers, hindering their participation in APN. While existing policies mention APN, the study highlights partial and limited implementation, calling attention to the need for improved, localised strategies. Trust emerged as the cornerstone of the APN process, shaping both patient and provider engagement. Trust-building strategies were important for establishing a secure environment for APN. Furthermore, the study revealed gendered dynamics in APN through which care responsibilities such as mediating between providers and male sexual partners further exacerbated the feminization of HIV. Thus, the desire for greater control, agency, and shared decision-making became evident. The exploration of FBOs in APN provision also suggests the importance of holistic care, considering spiritual and medical dimensions of healthcare journeys. Drawing parallels between COVID-19 and HIV contact tracing, the study emphasises the unique challenges posed by different contexts