4. Electronic Theses and Dissertations (ETDs) - Faculties submissions

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Taphonomy and palaeoecology of a monospecific microvertebrate bonebed: behavioural implications for the late Permian (Lopingian) parareptiles
(University of the Witwatersrand, Johannesburg, 2024-06) Mukwevho, Lutendo; Choiniere, Jonah; Smith, Roger
Sociality in the vertebrate fossil record is a dynamic and fast-expanding area of research. Natural history observations of living animals are crucial for understanding and categorizing sociality, but these observations are not feasible for extinct species. Monotaxic bonebeds provide unique opportunities to conceptualize the social behaviours of these extinct animals. An unusual bonebed (SAM-PK-K11289) discovered in the uppermost Permian strata of the Balfour Formation, Karoo Supergroup, in the Eastern Cape presents a window into the sociality of Late Permian reptiles. The use of propagation phase-contrast synchrotron X-ray microcomputed tomography permitted the 3D reconstruction of skeletal elements in SAMPK-K11289, allowing the taxonomic identification of the individuals in the bonebed as most likely belonging to Owenetta. This is the largest aggregation of Owenetta individuals known to date, with a minimum number of 31, which are all very similar in body size. The ontogenetic profile of SAM-PK-K11289 was interpreted by analysing the size distribution of duplicate elements and by making comparisons with other Owenetta and procolophonid specimens. The specimens in the bonebed are all osteologically immature, indicating that they are juveniles. The bonebed occurs in a pedogenically modified ripple cross-laminated siltstone suggesting that a low-energy fluvial sedimentation likely contributed to the modification, disturbance and disarticulation of elements before the bonebed was buried at or very close to the death site. This bonebed provides novel information that directly challenges the popular belief that reptiles and their ancestors are non-social or asocial. Considering the overall circumstances of the bonebed, I hypothesize that Owenetta rubidgei juveniles were socially gregarious and this behaviour may have been induced or influenced by environmental changes during the early extinction phase of the end Permian mass extinction in the Karoo Basin.
Uhambo Lwabo: A Narrative Study of Black Dramatherapists’ Perspectives on the South African Drama Therapy Field
(University of the Witwatersrand, Johannesburg, 2024) Shabangu, Nobantu
The question of visibility as a representation gap in Drama Therapy underpins this research. Official department records show that approximately 80 percent of the total student cohort between 2014 to 2021 were women and of that percentage less than a third comprised of Black female students. According to Jones (2013), the “drama” part involves theatre, embodiment, and shamanistic qualities of performance, dance, ritual, and metaphor form part of the therapy process. As such, metaphor becomes a language for the exploration and expression of traumas, furthermore its power lies in interpretation for the means of psychoanalysis through psychodrama. Additionally, the practice is informed by classical psychology: the empirical scientific study of human cognition and behaviour. Linking back to metaphor, the research argues that despite the foundational underpinnings of the field, Drama Therapy relies on notions of the person that are still conditional to a universalising and standardized notion of the Human that make the practice of the field alienating. Similarly, Tamale (2020) articulates invisibilising as a present and exploitative by-product of colonialism still active in universities which are founded on coloniality and thus render Black bodies and their intellectual products invisible. Therefore, the research examines how dramatherapy is affected through invisibilisation and as such interrogates its complicity. Consequently, the research takes on an Afro-feminist onto-epistemological response. Five semi-structured interviews were conducted with Black women dramatherapists. Chapter 1 outlines the background of research as an outsider to the dramatherapy field and learning of the discipline from dialogues outsides of the institution thus forming my rationale. Chapter 2 is the literature review which reveals the trend of invisibilising Black students within psychology, dramatherapy foundations and the post-colonial conditions of becoming a dramatherapist. Chapter 3 summarises the methodology of narrative, the analysis method, and the role of being an insider- researcher and reflexivity. Chapter 4 presents the narratives and themes that signal to invisibilisation. Chapter 5 provides Black women dramatherapists perspectives in response and resistance to being invisibilised. Chapter 6 is the conclusion which surmises the composite implications of this research. The research demonstrated an enduring practice of invisibilising Black dramatherapy students through the low annual student intake. Secondly, that invisibilising takes place within the master’s year through teaching material and the role of clinical supervision. Lastly, the invisibilisation of Black dramatherapists extends into the profession within professional representative bodies as well as through department cultures.
Pricing Interest Rate Derivatives Using The Forward Market Model
(University of the Witwatersrand, Johannesburg, 2024-10) Konaite, Tshana Tumelo; Mudavanhu, Blessing
The IBOR are due to be discontinued and their replacements have been chosen to be the overnight rates. This change in the risk-free rate comes with challenges of how the new rates will be modelled and how the products will be priced. In this dissertation, we look to explore the classical short-rates and the new generalized Forward Market Model proposed by Andrei Lyanschenko and Fabio Mercurio in 2019. We seek to utilize this model in pricing interest rate derivatives such as caps and swaptions.
Metagenome sequencing of the lichen species Flavopunctelia flaventior and Parmotrema tinctorum from Gauteng, South Africa
(University of the Witwatersrand, Johannesburg, 2024-06) Katane, Malebogo Dimpho; Botes, Angela; De Maayer, Pieter
Lichens are defined as a mutualistic association between fungi (mycobiont) and an algal and/or cyanobacterial photobiont. Increasing evidence suggests that lichens comprise more diverse microorganisms than initially thought, where lichens represent an interaction between archaea, bacteria, filamentous fungi, green algae, yeasts, and viruses. Not many comprehensive studies have been done of South African lichen species. The present study employed metagenome sequencing to investigate the lichen microbiomes of Flavopunctelia flaventior and Parmotrema tinctorum sampled from Bryanston, Gauteng province, South Africa. Furthermore, the roles played by the members of the lichen microbiome within symbioses were also studied by functionally annotating the assembled metagenomes of the two lichen species. This study sets the groundwork for future studies on South African lichen species. In Chapter 1, an extensive literature review on lichens, their ecology, taxonomy and biology is discussed. Furthermore, it delves into the existence and shape of the microbiome beyond the mycobiont and the photobiont. Additionally, possible roles that the lichen microbiome may play in sustaining the lichen symbiosis is also discussed. In Chapter 2, the metagenomes of two lichen species were sequenced, the quality of the reads were assessed, and taxonomic classification was performed to elucidate the composition of microorganisms associated with each lichen species. Both microbiomes were dominated by bacteria, with limited fungi, viruses, and archaea. The majority of the identified phyla and genera were found to be common between the two lichen species. Similarities in the core microbiome was accounted for by the fact that F. flaventior and P. tinctorum were sampled from the same location and they are both members of the Parmeliaceae family. In Chapter 3, the metagenomic reads were assembled and functionally annotated using various bioinformatics tools. We demonstrate that the members of the lichen microbiome are involved in the cycling of nutrients such as carbon and nitrogen. We also found differences in carbon fixation pathways, which were attributed to the accessory microbiome. Finally, a summary highlights key results and recommendations on future work that could be undertaken to further provide insight into biological pathways essential to sustain the lichen symbiosis.
Communal Equity: Reimaging Educa4onal Infrastructure in Soweto
(University of the Witwatersrand, Johannesburg, 2024) Pillay, David Jonathan
In defining the urban environments of modern-day South Africa, the remnant history of separate development has so deeply disrupted the equality between our communities that they remain a challenge today. While there are efforts towards seeking a balance between communities, identified in the City of Johannesburg’s nodal development schemes, the approach through which they are carried out may be exhibiting limiting results. Equal development can often be implemented by replicating rigid templates of the ideal infrastructure across communities. These infrastructure which perform essential functions neglect the opportunity to adapt and evolve to the context and history of the populations they serve. Within this research report, the City of Johannesburg’s development of Jabulani, Soweto, will be assessed and their need for improved facilities and access within primary schools will be highlighted and addressed through an architectural intervention which reimagines educational space around the principle of equity.
Improving Iterative Soft Decision Decoding of Reed Solomon Codes Using Deep Learning
(University of the Witwatersrand, Johannesburg, 2024) Nkiwane, Kimberly Ntokozo
Telecommunications in the current information age is increasingly dependent on efficient transmission of data through a noisy channel. Therefore, utilizing For- ward Error Correction (FEC) in the development of decoding algorithms is an active area of research. This dissertation work focuses on exploiting deep learn- ing techniques and error correction techniques to improve iterative soft decision decoding of Reed Solomon codes (RS). The parity check matrix of RS codes is characterized by a dense structure. This directly affects the exchange of soft information during the iterative decoding process. Therefore, to counter this issue, a bit-level implementation is utilized with the proposed decoding approach. Furthermore, additional techniques to add sparsity to the parity check matrix are presented in this research work. The proposed method for adding sparsity leverages the cyclical properties of RS codes to add low rate rows to the parity check matrix. This sparse implementation aids with the exchange of soft information during the message passing stage of the proposed iterative decoding process. The implementation of deep learning techniques to improve iterative soft decision decoders are also presented in this dissertation. The proposed approach makes adjustments to the Neural Belief Propagation (NBP) algorithm for RS codes. The proposed NBP utilizes the sparse implementation presented in this research to improve exchange of soft information. This in turn leads to gains in error correction performance without further adding complexity which is one of the main advantages of incorporating neural networks in the iterative decoding process. Additionally, this dissertation proposes a Graph Neural Network (GNN) imple- mentation for iterative soft decision decoding of RS codes. The approach employs the GNN architecture to construct a fully connected graph. This graph represents a message passing algorithm based on the Tanner graph, with trainable weights assigned to the graph nodes. This implementation improves the error correction performance of the proposed iterative soft decision decoder while reducing the number of iterations required to decode the received vector.
The effect of cholesterol depletion on TGF-ß-induced epithelial-mesenchymal transition in pancreatic cancer cells
(University of the Witwatersrand, Johannesburg, 2024-06) Breytenbach, Andrea; Kaur, Mandeep
Pancreatic ductal adenocarcinoma (PDAC) is a highly metastatic cancer that relies on the epithelial to mesenchymal transition (EMT) program for its spread. EMT is a cell plasticity program that involves the reorganization of cell structure as cells transition from an epithelial to a mesenchymal phenotype. The dysregulated cholesterol metabolism resulting from metabolic reprogramming in PDAC is thought to play a role in EMT by affecting EMT-related signalling pathways. However, no publication has yet investigated the impact of EMT on cholesterol content in PDAC. To shed light on these dynamics, EMT was induced in PANC-1 cells using TGF-β1, thereafter the effect of cholesterol-depleting agents (KS-01 and methyl-β-cyclodextrin) alone or in combination with chemotherapeutic agents (Gemcitabine (GEM) and 5-Fluorouracil (5-FU)) on cholesterol content, EMT state, drug resistance, and invasion were investigated. Our results showed that mesenchymal cells rely on reduced membrane cholesterol levels, synthesis, and uptake, while storing more cholesterol and promoting efflux. EMT also promoted drug resistance via upregulation of ABCB1 expression and reduced hENT1 expression. Targeting cholesterol using cyclodextrins promoted a cholesterol compensatory mechanism, leading to a hybrid EMT state, drug resistance, and metastatic potential. Treating mesenchymal PANC-1 cells with GEM or 5-FU monotherapies were seen to promote EMT-transcription factors, as well as promote cholesterol efflux, synthesis, and import, an unexpected result as these chemotherapeutic agents are not known to affect cholesterol. When GEM was combined with KS-01, drug resistance, invasion, EMT-transcription factors, vimentin, and E-cadherin was promoted indicating the promotion of a hybrid EMT state. Interestingly however, combining KS-01 with 5-FU resulted in an interplay that was seen to mitigate the EMT-promoting effects typically associated with cholesterol depletion alone. The exact mechanism linking the cholesterol compensatory mechanism to EMT remains complex and unknown. Based on work presented in this dissertation, it is proposed that targeting cellular cholesterol should be continued to be investigated, particularly in understanding the repercussions of the use of cholesterol depleting agents for the treatment of other disorders in patients with PDAC.
Modelling and analysis of COVID-19 outspread at micro-levels using spatial autocorrelation: Case of eThekwini
(University of the Witwatersrand, Johannesburg, 2024-09) Ngubane, Samukelisiwe; Chimhamhiwa, Dorman; Adam, Elhadi
The alarming effects of the COVID-19 pandemic on different socio-economic spheres have been felt across the globe. These destructive effects have prompted plenty of research to understand and control the coronavirus pandemic. Notably, one strategic method of mitigating the effects of the coronavirus epidemic has been the utilisation of spatial and geostatistical models to gain insights into the potential predictors of the prevalence of the coronavirus. Considering the above, it was the aim of this study to explore the use of advanced geospatial modelling and analysis techniques, including Moran’s I, spatial error models, spatial lag models, MGWR, and GWR for analysing and modelling the settlement level determining factors of COVID-19 incidence within the eThekwini Metro to inform effectual micro-level planning. Notably, the lack of micro-level modelling of COVID-19 prevalence predictors also motivated the undertaking of this study. To the above aim, the objectives of the research were to utilise spatial autocorrelation to map the granular level COVID-19 spatial distribution over the 3rd wave in the eThekwini Metro, compare the applicability of global and local models in analysing and modelling micro-level COVID-19 incidence, analyse the spatial dependence of the occurrence of COVID-19 on local level variables through Moran’s I and to spatially model the effects of significant local-level determinants on COVID-19. The incidence of COVID-19 cases for the 3rd wave, which was from the 2nd of May 2021 to the 11th of September 2021, was analysed and modelled. The Moran’s I result illustrated that COVID-19 incidence within the eThekwini settlement places had a positive spatial autocorrelation, with a Moran’s I value of 0.14 and a p-value of 0.00. Also, the MGWR model's local R2 value was greater (72.5%) as compared to the other models. Moreover, economic wellness score, the sum of TB cases and population density came out as the significant determining factors of settlement level incidence of COVID-19. This research report offers a great foundation for gaining insights into the applicability of advanced geospatial models in guiding targeted COVID-19 interventions at lower levels.
Envisioning Empowerment: Crafting a Realm of Learning for Visually Impaired Scholars in Mondeor
(University of the Witwatersrand, Johannesburg, 2024) Van Heerden , Stefan
To address the critical need for more inclusive schools in South Africa, this project focussed on designing a school for visually impaired learner in Mondeor, Johannesburg. Currently, only three of these schools exist in Gauteng, which limits the opportunity for children with visual impairment to access quality inclusive education. My proposal aimed to change this, by making education accessible to the visually impaired . According to the White Paper 6 model, children between the ages of 7 and 15 need to be in school. This project placed the building where it would likely have maximum impact in terms of assisting the communities in the chosen area. The location of the school should not dictate who can attend. Anyone who is able to enroll will be able to do so, with preference being given to the visually impaired. The research and the building design aimed to create an inclusive building and to question what an architectural design for the visually impaired would entail. The research delved into experimentation and architectural precedents. The experimentation involved a sensory analysis, during which I spent time blindfolded to get a better sense of what it is like to be blind. The outcomes of these experiments informed the design of the school. The project examined various design precedents for these types of buildings and used the human body as an important design concept. I envisioned the classrooms as the centre points or nodes of the design, similar to the core of a human body, branching out, like limbs, into the different services that the building will offer. The building design aims to engage with the community by having a percentage of its site allocated to public space. This will hopefully ensure that the public can be involved in the inner workings of the school, creating a sense of place and belonging. The building presents opportunities for prototyping a circular economy, thereby enriching the residential context. These combined concepts and ideas strengthen the connections between the research and design development for a building of this nature. I can briefly conclude that the integrated research methods did assist in creating a design proposal that places itself into the context.
Envisioning the Future of Fashion: The Creation And Application Of Diverse Body Pose Datasets for Real-World Virtual Try-On
(University of the Witwatersrand, Johannesburg, 2024-08) Molefe, Molefe Reabetsoe-Phenyo; Klein, Richard
Fashion presents an opportunity for research methods to unite machine learning concepts with e-commerce to meet the growing demands of consumers. A recent development in intelligent fashion research envisions how individuals might appear in different clothes based on their selection, a process known as “virtual try-on”. Our research introduces a novel dataset that ensures multi-view consistency, facilitating the effective warping and synthesis of clothing onto individuals from any given perspective or pose. This addresses a significant shortfall in existing datasets, which struggle to recognise various views, thus limiting the versatility of virtual try-on. By fine-tuning state-of-the-art architectures on our dataset, we expand the utility of virtual try-on, making them more adaptable and robust across a diverse range of scenarios. A noteworthy additional advantage of our dataset is its capacity to facilitate 3D scene reconstruction. This capability arises from utilising a sparse collection of images captured from multiple angles, which, while primarily aimed at enriching 2D virtual try-on, inadvertently supports the simulation of 3D environments. This enhancement not only broadens the practical applications of virtual try-on in the real-world but also advances the field by demonstrating a novel application of deep learning within the fashion industry, enabling more realistic and comprehensive virtual try-on experiences. Therefore, our work heralds a novel dataset and approach for virtually synthesising clothing in an accessible way for real-world scenarios.

4. Electronic Theses and Dissertations (ETDs) - Faculties submissions

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