An investigation into fatigue prevalence amongst citrus packhouse sorters in the Eastern Cape province of South Africa
- Authors: Robinson, Harry Jack
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424312 , vital:72142
- Description: Background: South Africa is the second most influential exporter of citrus fruits internationally and holds a pivotal role in economic revenue for the country. Rural areas, such as the Sundays River Valley in the Eastern Cape province of South Africa, contribute to the country’s citrus production. Many women depend on citrus packhouses for employment as citrus sorters. As humans perceive certain defects in citrus fruits more accurately than machines, these sorters must identify and manually remove any fruit that does not conform with export requirements. Citrus sorters are exposed to numerous physical and cognitive stressors during the task while faced with organizational challenges, such as shift work and long working hours. Therefore, the potential for fatigue development is anticipated. Given the multifactorial nature of fatigue and the negative consequences it may have on workers, it also has the potential to impede the accuracy of the sorting performance. Stringent disciplinary action for the entire South African citrus industry may be of consequence if nonconforming or pest-infested fruit is missed by citrus sorters and exported to foreign countries. This study aimed to investigate the prevalence of fatigue among citrus sorters in a citrus packhouse in the Sundays River Valley of the Eastern Cape throughout a citrus harvesting season and to identify factors that may contribute towards fatigue development. Methods: The research design utilized a crosssectional, two-part approach that applied mixed methods. Part one was administered once-off, incorporating demographic, work-, and non-work-related questions. Part two was a self-developed repeated measures assessment comprising close-ended contextual questions, the Modified Fatigue Impact Scale, and the Karolinska Sleepiness Scale. Environmental and work output data were also recorded. Results: Citrus sorters (n= 35) recorded a mean MFIS score of 39.35 throughout the harvest season, which was above the prescribed fatigue threshold (38). However, there was no significant difference in fatigue ratings over time (p= 0.122). Day shift workers exceeded the fatigue threshold for the entire season compared to night shift workers, who only exceeded it in the last two weeks. The physical, cognitive, and psychosocial subscales found no significant difference in fatigue scores, although physical fatigue recorded the highest scores across all weeks and displayed a significant difference over time. Overall, participants, on average, perceived to be “neither sleepy nor alert” over the season. However, eight participants (22%) recorded sleepiness scores ii exceeding the excessive sleepiness threshold of seven. Educational levels, health status, work-pace, and the number of family dependents significantly contributed to fatigue development, albeit a weak correlation. Discussion: Sorters were perceived to be fatigued from week three till the end of the study; however, there was no variation in fatigue scores over time. An accumulation of physical fatigue over time was revealed where prolonged standing, repetitive work, and irregular working postures may have contributed. Night shift workers did not receive the recommended hours of sleep (7-8 hours); hence, they registered greater sleepiness scores over the season than day shift workers. Environmental and work output recordings did not prove to have a significant influence on fatigue development, and neither did work experience or physical exercise. Conclusion: An amalgamation of numerous contributing factors within the work situation, private situation, and the individual influenced the development of fatigue, where there was no primary causal factor. Future studies should consider recording the accuracy of the sorting performance to acquire rich, objective data. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
Analysing equity and ethical dimensions of water governance challenges in the lower section of the upper Vaal River catchment, Gauteng, South Africa
- Authors: Tavengwa, Noleen Shamiso
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424199 , vital:72132
- Description: Poor water governance practices have been identified as one of the root causes of water problems confronting the South African water sector. This is evident in the lower section of the Upper Vaal River Catchment, where ineffective implementation of the regulatory measures has resulted in multiple incidents of illegal discharge of effluent from municipal wastewater treatment works, industrial and mining activities. Pollution and deterioration of water quality is a major challenge in the catchment; the Vaal River is severely polluted beyond acceptable standards and impacts negatively on other water users who have legitimate rights to the water resources. Pollution not only affects human activities and use, but also has negative impacts on ecological health and functionality. Poor water governance practices raise ethical implications for the rights to water for both social and ecological components. Although many water governance challenges in South Africa have implications that border on values and ethics, the relationship between these concepts has hardly been explored. In order to contribute towards filling this gap, this study explores water governance challenges and their ethical implications, and then analyse the equity dimensions of key water challenges among institutional actors in the lower section of the Upper Vaal WMA, Gauteng. The study uses a qualitative research approach which involves several methods of data collection: document analysis, workshops, focus group discussions, key informant interviews and participant observation. The data collected were analysed using thematic analysis, and then applied an ethical framework to distil ethical implications of the identified water governance challenges. There are five water governance challenges that were identified, which are i) failure in the implementation of water legislation and regulations, ii) ineffective leadership and management, iii) cooperative governance and poor accountability, iv) decentralisation and ineffective participation, and v) finance, infrastructure, and technical capacity. The deterioration of water quality and pollution due to ineffective implementation of the regulatory system has ethical implications towards protection of the ecological system and sustainable management of the water resources for the present and future generation. Ineffective implementation of the regulatory measure also raises the issue of distributive equity between different water users and between current and future users. These implications are critical particularly when viewed from the perspective of systemic-relational ethical approach which posit that in social-ecological systems, all components ought to be treated with equal regards, and their inherent worth respected in order to maintain the unity of the SES. The idea of equal regards to the inherent worth of the component implies due respect, in ways that do not undermine the integrity of the entire system. The challenges identified in the system suggest that i) the right of the ecological system to water is undermined due to anthropogenic activities, which may in the long term undermine the functionality of the entire SES; ii) the right of the margined to access to water of the right quality is also undermined, and pollution costs is externalised. These are matters of ethics that thus deserved attention in policy and management considerations. The study analysed equity dimensions (distributive and procedural), targeting the key institutional water users (i.e., mines, industries, agriculture, municipalities, and the wastewater treatment works) in the lower section of the Upper Vaal River Catchment as equity candidates due to their activities that significantly impact the environment and the water resources. The cost of pollution caused by mining activities, industrial activities and the wastewater treatment works is externalised to other users who are not responsible for the pollution. In this regard study identified key drivers that raise concerns linked to distributive equity, which are ) pollution and water quality deterioration, ii) the legacies of mining activities, and iii) poor infrastructure maintenance, vandalism, and theft. Identifying these key drivers of distributive equity concerns is critical in ensuring that the water governance processes are designed in a way that stakeholders and actors reliant on water resources within the catchment have equitable and fair access without the effects of externalised costs from other actors. The identified water governance challenges in the catchment all borders on ethics, thus an ethical framework is crucial in tackling water related problems. The principles of ethics can be used as guidelines to decision-making process for the management and governance of water resources in South Africa. Therefore, implementing and incorporating principles of the systemic-relational ethics into policy making and water resources management will yield sustainable, efficient, and equitable use and management of water resources. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
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- Date Issued: 2023-10-13
Analysis of the role and regulation of HOP1a and HOP1b splice variants in cancer biology
- Authors: Schwarz, Kelly
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432240 , vital:72854
- Description: Restricted access. Expected lease date in 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
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- Date Issued: 2023-10-13
Application of in vitro release testing (IVRT) to assess “sameness”/differences of topical clotrimazole formulations
- Authors: Wellington, Hannah Margaret Mary
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419599 , vital:71658
- Description: Embargoed. Possible release date early 2025 pending publications. , Thesis (MSC Pharm) -- Faculty of Pharmacy, 2023
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- Date Issued: 2023-10-13
Application of web design techniques and best practices in implementing web development, maintenance and enhancement of RUBi websites and web application systems
- Authors: Tshabalalala, Thulani
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424688 , vital:72175
- Description: The popularity of the web has seen various fields, such as the sciences taking advantage of this resource to further their scientific endeavours. This has seen science groups moving into developing websites and web applications, and such a group is the Research Unit in Bioinformative (RUBi). With the use of the web, the development and maintenance of whatever web-related tools become inevitable, given the continuous changes in the web space. This continuous evolution of web development and maintenance will come with techniques, principles and standards which will not only enable faster development of web entities but also ensure that modern hardware, fulfilment of the requirements to use such hardware and modern concepts are incorporated into forming web tools that enable such progression. Furthermore, introducing the previously mentioned progress of the web becomes an essential part of its development and maintenance. This paper did implement the processes of progressing the web using the technique of documentation and version control systems. The web development for the COVIDRUG website was done for the Covidrug-Africa Consortium (COVIDRUG) using the Django webdevelopment framework. The RUBi website and the MDM-Task we band the Job Management System (JMS) web applications were maintained for the maintenance aspect. Archives brought value regarding the traceability it provides of the various web-related aspects. The development showed a website’s potential value, particularly for research groups. The maintenance carried out showed how different techniques and approaches could be used in different maintenance prospects to achieve set objectives. The development and maintenance resulted in websites and web applications that have the features stated in their respective maintenance plans. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2023
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- Date Issued: 2023-10-13
Arbuscular mycorrhizal fungi associated with maize in South Africa, under conventional and conservation agricultural cultivation
- Authors: Maússe Sitoe, Sílvia Natal David
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431846 , vital:72808
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
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- Date Issued: 2023-10-13
Arbuscular mycorrhizal fungi associated with wheat under conventional and conservation agricultural cultivation
- Authors: Dube, Makasithembe
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431688 , vital:72796
- Description: Access restricted. Expected release date in 2024. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Assessment of Pitman Model Capabilities in Modelling Surface Water-Groundwater Interactions in the Lake Sibaya Catchment, South Africa
- Authors: Ramatsabana, Phatsimo Pearl
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424188 , vital:72131
- Description: Difficulties arising from data scarcity, input data error or uncertainty, heterogeneous environments, lack of process understanding, and model structural uncertainty frequently constrain hydrological assessments of South African catchments. This research aimed to assess the usefulness of a “simpler” conceptual model for the conjunctive management of surface water and groundwater. The idea is that, to leverage the limited available data and information, a compromise between model complexity and data availability is required, which improves the use of models to produce reliable hydrological systems assessments. The research methodology focused on catchment-scale lake-groundwater dynamics to explore the limits of the groundwater components of the modified Pitman model (Hughes, 2004) in this type of environment, thus, determining the potential for using this model for integrated water assessments in South Africa. The Pitman model (Pitman, 1973; Hughes, 2013) is one of the most widely accepted models regarding surface water hydrology in South Africa; however, the newly incorporated groundwater components (Hughes, 2004) have not been applied as extensively as the surface water components. There remains uncertainty regarding their capability to adequately simulate groundwater processes and accurately represent surface and groundwater interactions in some environments. The model was assessed based on how well simulated water balance variables accurately reflected available evidence and expected catchment response (objective 1). Secondly, the research identified and addressed uncertainties as regards the structure and application of the model’s groundwater interaction components (objective 2). The model was set up for the Lake Sibaya catchment, which is a predominantly groundwater-driven system and, thus, provides an important opportunity to interrogate different aspects of uncertainty in both the conceptualizing and quantifying interaction processes. The study’s overall conclusion is that the model performed satisfactorily as it was able to simulate the lake’s water balance correctly enough such that the influences of dominating components were sensibly reflected in variations in streamflow and lake volumes. The following key findings were noted; (i) the lake volume shows a continuous decline, (ii) the lake volume decreased with increasing development (forestry and abstractions) in the lake catchment, (iii) there is significant rainfall uncertainty in the study area and the model showed high sensitivity to rainfall differences, (iv) robust conceptual knowledge of local catchment conditions was valuable for reducing some of the data related uncertainty in the study area and for producing realistic model simulations, (v) the Pitman model (Hughes, 2013) updated GW components can provide a valuable tool for modelling integrated hydrological processes; nevertheless, when applying the model to specific environments, implicit approaches may be necessary to account for processes that are not fully represented in the model. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2023
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- Date Issued: 2023-10-13
Asymmetrical zinc(II) phthalocyanines conjugated to nanomaterials for degradation of organic pollutants and inactivation of Staphylococcus aureus bacteria
- Authors: Mgidlana, Sithi
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431859 , vital:72809 , DOI 10.21504/10962/431860
- Description: This thesis reports on the syntheses and characterization of asymmetrical phthalocyanines (Pcs) with different ring substituents (tert-butyl, ester, diimide, trimethoxy, acetophenone, heptanoylphenoxy, perfluorophenoxy, dimethoxy, propanoic acid, acetic acid, carboxylic acid, aminophenoxy, acrylic acid). Several nanoparticles including metal tungstate, capped with glutathione and 1-mercaptohexanol are prepared and characterized using analytical techniques. The synthesized Pcs are covalently linked to various nanoparticles (NPs) through ester and amide bonds to form Pc-NP conjugates, in order to improve their catalytic properties. The Pcs and their conjugates are characterized using different analytical techniques. The photophysics and photochemistry of the MPcs and conjugates are studied. The conjugates T). The complexes and the conjugates with nanomaterials are evaluated for singlet oxygen-generating ability. Conjugates generate higher singlet oxygen in comparison to Pc complexes alone. The photocatalytic activity of the conjugates of ZnPc complexes with NiWO4, Ag2WO4, Bi2WO6, CoWO4, and Ag-Fe3O4-based nanoparticles is evaluated based on photodegradation of methylene blue, tetracycline, and dibenzothiophene. The photocatalytic efficiencies of the synthesized phthalocyanine complexes increased in the presence of nanoparticles. This work also reports on the photodynamic antimicrobial chemotherapy activity of these materials against Staphylococcus aureus (S. aureus) bacteria in DMSO. The results indicated that silver-based nanoconjugates exhibit high antimicrobial activity with high log reductions compared to NiWO4, CoWO4, and Ag-Fe3O4-based materials. The z-scan technique is employed to experimentally test the nonlinear optical response of complexes and nanoconjugates in solution. The nonlinear absorption coefficient, third-order optical susceptibility and optical limiting threshold of the materials are obtained from the Z-scan aperture data. The nonlinear absorption parameters improved in the presence of semiconductor quantum dots, with 1-ethanoic-CdTe/ZnSeS/ZnO giving the best results due to the presence of electron-donating substituents. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Beyond mastery: jazz, gender and power in postapartheid South Africa
- Authors: Williams, Ulagh
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432505 , vital:72876 , DOI 10.21504/10962/432512
- Description: This dissertation studies the musical lives of seven South African women who have built highprofile national and international careers as jazz musicians. Empirically it records self-reported experiences and actions that they have identified as relevant to their success within a notoriously patriarchal field. Drawing on feminist research methods and Interpretative Phenomenological Analysis the dissertation strives to develop an empathic yet critical epistemological framework attuned to the complexities of their lived experiences as women and as jazz musicians. Theoretically it investigates the power relations at play in the myriad ways they negotiate or have been impelled to negotiate gender and patriarchy as musicians. Chapter one draws attention to the ubiquity of patriarchy in South African and international jazz culture, and highlights the research participants’ numerous successes to date as performers, educators, composers, and bandleaders. Chapter two positions this study in relation to cognate work in South African jazz studies, international feminist jazz studies and feminist phenomenology. Chapters three to five successively consider the participants’ early enculturation as musical and gendered subjects, their agentic responses to structures of patriarchy and/or race as emerging and established professionals, and the ways these experiences have found expression in some of their musical utterances as performers and composers. Fusing art and activism, the participants challenge and transcend masculinist discourses of mastery that still dominate South African jazz as a field of production and aesthetic practice. , Thesis (PhD) -- Faculty of Humanities, Music and Musicology, 2023
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- Date Issued: 2023-10-13
Characterizing shift systems and exploring their effects on sleep and fatigue in South African freight railway operators
- Authors: Mona, Chumani
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424300 , vital:72141
- Description: Embargoed. Expected release date 2025. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
Comparison of the metabolic physiology of exploited and unexploited populations of red roman (Chrysoblephus laticeps) along the south coast of South Africa
- Authors: Nabani, Xolani Prince
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424358 , vital:72146
- Description: Anthropogenic-induced climate change and exploitation pose threat to many marine fishes on which a vast majority of people around the world depend. Rapid changes in sea surface temperature have a direct impact on the physiology of ectothermic organisms such as fish, potentially resulting in changes to population distribution, abundance, and demographics. In the face of climate change, the impacts of increasing temperature variability on fish populations may be exacerbated by exploitation. Understanding how the resilience of exploited populations is affected by climate change is critical to predict how fishes will respond in the future. This study aimed to augment our knowledge on the impact of exploitation and thermal variability on fishes by comparing the thermal physiology of an exploited and unexploited population of the resident, reef-dwelling, Chrysoblephus laticeps. Twenty live fish were collected from the exploited, Cape St Francis and 18 fish from the unexploited, Goukamma Marine Protected Area and transported to the laboratory. The metabolic performance, in terms of standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS) of individual C. laticeps were estimated repeatedly at 10 ℃, 16 °C and 21 °C. Linear mixed effects models were used to examine the relationship between temperature, population, and metabolic rate and a ‘cvequality’ test analysis was used to compare the variance structure of the metabolic rate regression model for each population. Overall, the findings of this study show that Chrysoblephus laticeps from the unexploited population maintains a significantly higher aerobic scope (AS) across all temperature treatments (10, 16 and 21 ℃) when compared with those from the exploited population. In addition, the maximum metabolic rate (MMR) of individuals from the unexploited population was significantly higher than that of individuals from the exploited population, but there was no evidence to suggest that variability was significantly different between the populations. On the other hand, the individuals from an exploited population had a significantly higher standard metabolic rate (SMR) at high temperatures of 21 ℃, while the unexploited population had a low SMR at these high temperatures, but a high SMR at 10 ℃. Despite these differences there was no significant variation in the SMR between the two populations. The findings of this study confirm previous work on different exploited and unexploited populations of C. laticeps and together these findings suggest that hook and line exploitation lead to reduced physiological phenotypic diversity and reduced physiological performance in exploited fish populations. These findings emphasise the importance of incorporating the iii physiological information to develop viable fisheries management tools in the context of climate change. This study also highlights the effectiveness of MPAs in conserving highperformance physiological phenotypes to maintain phenotypic diversity in fish populations. Future research should aim to evaluate the efficacy of existing MPAs in preserving the physiological diversity of important hook and line fisheries species, while fisheries managers should consider augmenting their approaches through the incorporation of well-designed MPA’s to promote physiological diversity. This will be critical to advance the development of sustainable management practices, not only in a South African context but globally, where oceanic and coastal environmental conditions are expected to rapidly change in the future. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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- Date Issued: 2023-10-13
Composition and physiological roles of gut microbiota in the False Coding Moth (Thaumatotibia leucotreta)
- Authors: Richardson, Perryn Heather
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424457 , vital:72155
- Description: Gut microbiota can have a profound influence on host performance, behaviour and fitness. For False Codling Moth (FCM), Thaumatotibia leucotreta (Lepidoptera: Tortricidae), a major pest of citrus in South Africa, little work has been undertaken to date on gut microbe diversity or its influence on the host. This thesis aimed to i) characterise the gut microbiome of FCM under laboratory conditions and in FCM from the field, ii) and produce moths with reduced gut microbiota through egg dechorionation, which was followed by iii) the measurement of a suite of physiological traits, namely mass, survival and thermal stress in FCM from normal laboratory, dechorionated laboratory and field collected larvae that may be indicative of overall field performance. We aimed to directly test the hypothesis that gut microbial diversity partly determines insect performance and fitness by measuring its effects on growth, development, and tolerance to cold temperatures in FCM. FCM eggs that underwent dechorionation with sodium hypochlorite had an overall effect on larval survival, egg morphology and both larval and adult moth physiological measures. Increasing concentrations of sodium hypochlorite significantly decreased insect survival, (𝜒2(1, n = 10 850) = 21.724, p-value < 0.0001), with a concentration of ≈3.69% as the concentration limit (p-value < 0.001). Successful dechorionation of FCM was achieved with a wash of sodium hypochlorite at around 3.69% concentration and was visually confirmed by reduction of FCM egg surface area, (𝜒2(25, n = 260) p-value < 0.0001) and Scanning Electron Micrographs of the egg morphology. The gut microbiome of FCM from the different focus treatments was successfully characterized. Identification of the dominant bacterial families in these microbiomes revealed Xanthobacteraceae, Beijerinckiaceae and Burkholderiaceae in both the laboratory reared and field collected larvae, which suggests their systematic association with T. leucotreta. The most abundant genera were revealed as Bradyrhizobium, Methylobacterium and Burkholderia-Caballeronia-Paraburkholderia. Comparison of larval mass showed that treatment (dechorionated or not) had a significant effect on larval mass (𝜒2(2, n = 230) = 22.703, p-value < 0.001), field larvae were heavier than both control larvae and larvae with a disrupted gut microbiome. However, adult insects with a disrupted gut microbiome had more mass than individuals from the control and field-collected larvae with intact gut microbiomes (𝜒2(2, n = 230) = 39.074, p-value < 0.001). Despite the difference in mass between larval treatments, there was no significant difference in relative protein (𝜒2(2, n = 24) = 5.680, p-value = 0.06), carbohydrate (𝜒2(2, n = 24) = 3.940, p-value = 0.14) or lipid (𝜒2(2, n = 24) = 6.032, p-value = 0.05) content between individuals from the control and dechorionated treatments and field-collected individuals. Turning to thermal physiology, insects collected from the field took significantly longer to recover from chill coma than both laboratory treatments with intact and disrupted gut microbiomes (𝜒2(2, n = 129 = 39.659, p-value < 0.001). In addition, exposure to cold stress showed that treatment had a significant effect on insect mortality (𝜒2(2, n = 272) = 9.176, p-value = 0.01), with individuals from the control and dechorionated treatment being less likely to die after experiencing cold stress compared to field-collected individuals. Differences in the mass and thermal tolerance of insects with intact and disrupted gut microbiota suggest that gut microbiota may play an important role in the cold performance of T. leucotreta, and these findings constitute the basis for future molecular work on the functions of these bacterial taxa. This research highlights the need for consideration of the effects of T. leucotreta microbiome in current pest control programs. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-10-13
Computational studies in human African trypanosomiasis
- Authors: Muronzi, Tendai
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431883 , vital:72812 , DOI 10.21504/10962/431885
- Description: Human African trypanosomiasis (HAT) is a neglected tropical disease (NTD) caused by two subspecies of the parasite, namely Trypanosoma brucei (Tb) gambiense (g-HAT) and rhodesiense (r-HAT). HAT is endemic in sub-Saharan countries, where the parasite transmission vectors, tsetse flies, breed. An estimated 70 million people remain at risk of contracting the disease, where the infection is classified as acute or chronic for g-HAT and r-HAT, respectively, with both forms ending in fatal meningoencephalitis when left untreated. Both g-HAT and r-HAT are responsible for widespread fatal epidemics throughout sub-Saharan African history, resulting from the complex molecular interplay between trypanosomes and humans through unique, innate immunity evasion mechanisms. Of interest, the Tbr subspecies expresses a serum resistance-associated protein (SRA), which binds to human serum lytic factor, apolipoprotein L1 (ApoL1), nullifying any trypanocidal activity. In response, ApoL1 (G1 and G2) variants found in humans of sub-Saharan African lineage have been cited for conferring resistance to the r-HAT infection in an interaction that is not fully elucidated In the event of successful infection, current HAT chemotherapeutics are plagued with complexity of administration, poor efficacy, toxicity, and potential drug resistance, highlighting a need for improved approaches. The parasite folate pathway provides a strategic target for alternative anti-trypanosomal drug development as trypanosomatids are folate auxotrophs, requiring host folate for growth and survival. Validated drug targets pteridine reductase (TbPTR1) and dihydrofolate reductase (TbDHFR) are essential for salvaging cofactors folate and folate biopterin crucial to parasite survival, making them viable targets for anti-folate investigation. The overall aims of this thesis were to a) provide insights into the molecular and dynamic basis of the SRA and ApoL1 interplay in HAT infection and b) identify safer and more efficient anti-folate anti-trypanosomal drug alternatives through in silico approaches. To achieve our first aim, in silico structure prediction was applied to generate 3D models of ApoL1 C-terminal variants G0, G1, G1G/M, G2 and G1G2, and four SRA variants retrieved from the NCBI database. The SRA and ApoL1 structures were inspected dynamically to identify the effect of the variants through molecular dynamics (MD) simulations. Dynamic residue network (DRN) analysis of MD trajectories was fundamental in identifying residues playing a vital role in the intramolecular communication of both proteins in the presence of mutations. Protein-protein docking was then applied to calculate plausible SRA-ApoL1 C-terminal wild-type complex structures to further elucidate the nature of SRA-mediated infection. Through MD simulations, twelve SRA-ApoL1 dimeric structures were narrowed down from five to two energetically sound complexes. The two feasible SRA-ApoL1 complexes (1 and 2) exhibited favourable communication observed through DRN analysis, including the retaining key communication residues identified in prior monomer DRN calculations. ApoL1 C-terminal variants were additionally incorporated into SRA-ApoL1 complexes 1 and 2 for further complex dynamics analysis This investigation into the nature of SRA-ApoL1 binding resulted in five primary outcomes: 1) highlighting the intramolecular effects ApoL1 variants have on the stability of the protein, 2) the identification of crucial SRA and ApoL1 communication residues in both monomeric or dimeric form, 3) the isolation of feasible SRA-ApoL1 complexes determined through global and local structural analyses 4) identification of residues crucial to the complex formation and maintenance of SRA-ApoL1, overlapping with those identified in (1), and 5) the minimal dissociative role of the G1 mutations in the complex, but compounding effect of the G2 deletion mutation. Computational modelling and drug repurposing were employed to achieve the thesis's second aim as they drastically cut down the costs involved in drug discovery and provide a more time-efficient screening method through numerous drug candidates. Using high throughput virtual screening, a subset of 2089 approved DrugBank compounds were screened against TbPTR1. The outputs were filtered to 24 viable compounds in 54 binding poses using binding energy and molecular interactions. Through subsequent MD simulations of 200ns, thirteen potential hit compounds were identified. The resultant hit compounds were subjected to further blind docking against TbDHFR and molecular dynamics to identify compounds with the potential for dual inhibition. The filtered subset was also tested in in vitro single concentration and dose-response bioassays to assess inhibitory properties against Trypanosoma brucei, complementing in silico findings. Post-molecular dynamics, four compounds exhibited high stabilities and molecular interactions with both TbPTR1 and TbDHFR, with two presenting favourable results in the in vitro assays. Three compounds additionally shared common structural moieties. In all, the in silico repurposing highlighted drugs characterised by favourable interactions and stabilities in TbPTR1, thus providing (1) a framework for further studies investigating anti-folate HAT compounds and (2) modulatory scaffolds based on identified moieties that can be used for the design of safe anti-folate trypanosomal drugs. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2023
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- Date Issued: 2023-10-13
COVID19 and accountability in South Africa: legislation, ethics and disaster risk management
- Authors: Chapman, Emma Deidre
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419565 , vital:71655
- Description: Embargoed. Possible release in 2026 pending publication. , Thesis (MSC Pharm) -- Faculty of Pharmacy, 2023
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- Date Issued: 2023-10-13
Design of an LMS-mediated tutorial to support deep and effective engagement in the process of learning mathematics
- Authors: Kigundu, Stephen
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431565 , vital:72786 , DOI 10.21504/10962/431565
- Description: Many institutions of Higher Learning have adopted a variety of Learning Management Systems (LMS) as platforms for e-learning implementation. However, the design and nature of LMS technologies present challenges to the design of LMS-based activities that engage students in learning to do mathematics. There are no clear guidelines or strategies for designing LMS-based activities that engage students in complex mathematical processes. Hence, using technologies in mathematics education often replicates instructivist positions and practices. Conversely, using constructivist principles, modes of mathematical engagement, and e-learning tools to mediate learning provides an integrated framework to transform the use of an LMS as a platform for e-learning implementation and promote deep engagement in mathematical learning. The objective of this study was to explore mechanisms that could be useful for conceiving activities to support the learning of Mathematics using an LMS-mediated tutorial. The design, redesign and evaluation of the e-tutorial are reported upon. In preparation for the study, an LMS-based tutorial was designed and developed to be used as a test-bed to investigate how these e-learning tools could support learning to do mathematics. A Trigonometry module, consisting of course content in the form of resources and tasks to help the students to explore, practice and apply right triangle concepts, was used to investigate and derive design strategies. A mixed method research approach with a reflexive self-study research design was used. A group of first-year university student volunteers studying mathematics in the mechanical engineering department were used to test the tutorial. The students were asked to do a series of tasks using the e-learning environment during the Mathematics tutorial period. Data was collected using in-class observations, interviews, screen capture videos, student-written responses, and system-generated data. All students were encouraged to complete a learning journal detailing their experiences during the tutorial using an LMS-based tool. The students were given no training, but a tutor (researcher) was available to answer any questions they may have had. Contradiction analysis was used to evaluate the data, compare purpose and practice and judge whether the activity or tool was fitted for the intended purpose. Findings were in the form of transformations of the e-tutorial system as it was developed. Among the most noteworthy contributory modifications were changing from 1) “read first, then do” to “do first, read when necessary”, 2) “work on the computer” to “work on paper then capture on the computer”, 3) “physically separated work with computer-enabled social contact”, to "individual computer work in face-to-face social settings.” 4) “single-level of resource provision” to “multi-level, demand-driven resource provision” and 5) “self-regulated” learning process regulation to “computer-assisted” learning process regulation. The discussion of these findings indicated that to enable students’ deep and effective engagement in the process of learning fundamental trigonometry within an LMS-mediated tutorial, one needs to design the system with some activities that can create a demand for knowledge, encourage rough work and face-to-face social interaction, supported by multi-level, demand-driven resources, and computer-assisted learning-process regulation. Contributions to research by this study were in the form of 1) Design Principles for LMS-mediated tutorials, 2) Principles for an e-tutorial development methodology, and 3) The LMS-mediated tutorial system. , Thesis (PhD) -- Faculty of Education, Primary and Early Childhood Education, 2023
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- Date Issued: 2023-10-13
Disaster risk management issues in WASH in South Africa: an examination of selected challenges and development of possible solutions
- Authors: Madikizela, Phindile
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431520 , vital:72782
- Description: Access restricted. Expected release date 2025. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2023
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- Date Issued: 2023-10-13
Discovery and classification of compact radio sources in the MeerKAT Galactic Centre data
- Authors: Rammala, Isabella Dineo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/432218 , vital:72852
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2023
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- Date Issued: 2023-10-13
Distribution and habitat preferences of marine megafauna in Nosy Be, Madagascar
- Authors: Lubbé, Alicea
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424710 , vital:72177
- Description: Marine megafauna have important ecological roles including the top-down regulation of lower trophic levels and the transport of nutrients. They are also charismatic species of socioeconomic importance, due to their public appeal and focus for ecotourism. However, these taxa face numerous anthropogenic threats including bycatch, habitat-loss, noise disturbance, prey reductions, pollution, and vessel traffic. Northwest Madagascar has been identified as an important marine mammal area and whale shark aggregation site, yet limited information on megafauna within Madagascar exists. In this thesis, I investigated the community structure, distribution trends, related environmental factors (Chapter 2) and predicted habitat suitability (Chapter 3) using a species distribution modelling approach for marine megafauna around Nosy Be, North-west Madagascar. Data collection consisted of opportunistic boatbased surveys conducted while looking for whale sharks, mobulid rays and cetaceans. These activities were performed by dedicated ‘swim with whale shark’ tourism operators, Les Baleines Rand'eau and Safari Baleine during tourism activities directed by the Madagascar Whale Shark Project over four years (2016-2019). A total of 1792 sightings were reported with 13 identified species, including elasmobranchs: whale shark, Rhincodon typus; spinetail mobula ray, Mobula japonica; giant oceanic manta ray, Manta birostris; shortfin devil ray, Mobula kuhlii; balaenids: humpback whale, Megaptera novaeangliae; Omura's whale, Balaenoptera omurai, delphinids: Indo-Pacific bottlenose dolphin, Tursiops aduncus; spinner dolphin, Stenella longirostris; pantropical spotted dolphin, Stenella attenuata; Indian ocean humpback dolphin, Sousa plumbea; false killer whale, Pseudorca crassidens; melonheaded whale, Peponocephala electra and one cheloniid species: leatherback sea turtle, Dermochelys coriacea. Sightings were spatially analysed at a community level according to feeding guilds (i.e., filter feeders vs. predators), and distribution of the megafauna groups v were compared to selected remotely sensed physico-chemical data (sea surface temperature and chlorophyll-a concentration) and bathymetry charts (depth and slope) using generalized linear models (Chapter 2). All four variables had a significant effect on filter feeder distribution. Spatial distribution of filter feeder sightings peaked at an area of steep underwater topography (18-50m; x slope=0.5%) located on the west coast of Nosy Be, where foraging aggregations of large filter feeders (primarily R. typus and B. omurai) were frequently observed. Only SST had a significant effect on the relative abundance of animals in the predator feeding guild, which demonstrated a more longitudinal distribution along the continental shelf. The maximum entropy model (Maxent) was used for predicting habitat preference for the most frequently sighted species (Chapter 3). The distribution of whale sharks, mobulid rays and Omura’s whales were significantly overlapped as they were abundant in two main hotspots, Grand banc de l’entrée (~10 km of the west coast) and near Nosy Mitsio island, (~50 km northeast of Nosy Be). Suitable habitat for the dolphins was in relatively shallow waters in temperatures <28ºC near areas of steep changes in bathymetry. Bottlenose and spinner dolphins had a more widespread distribution across the continental shelf and humpback dolphin was closely associated with inshore reefs and occur in waters <10m. The coastal and inshore region of Nosy Be is an important habitat for a variety of megafaunal species, and the continental shelf provided essential areas for feeding and breeding. The results were similar to those presented for these species in other regions of the Indian Ocean (i.e., Eastern and Southern Africa; Western Australia; Seychelles) as well as outside of the Indian Ocean (i.e., Indonesia; Caribbean; North Atlantic). Thus the results from this thesis could be considered for management recommendations for marine conservation in the region. The value and limitations of data collected by citizen science were outlined (Chapter 4). , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-10-13
Drought impacts on livestock and crop production along an urban-rural gradient: perceptions and response strategies in the Eastern Cape province, South Africa
- Authors: Pamla, Avela
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424732 , vital:72179
- Description: Drought is a major challenge threatening agricultural productivity in urban and rural areas across southern Africa. Drought events are expected to be more frequent, severe, last longer, and, impact land-based livelihoods in the coming decades. Despite the growing literature on the impacts of drought on livelihoods, there is limited focus on the impacts of droughts across rural-urban gradients. The study examined small-scale farmers’ perceptions of drought impacts and response strategies in the contexts of persistent droughts in the Eastern Cape province of South Africa. A total of 163 respondents, practicing livestock and/or crop farming across six towns, in urban and rural contexts were purposively identified. The study used snowball sampling approach to identify the relevant respondents. Data were collected through a semi-structured questionnaire survey, exploring the respondents' socio-demographic profiles, agricultural activities, perceptions of drought impacts, and drought response strategies. Qualitative data were coded and analyzed using descriptive statistics, thematic analysis, t-tests, and chi-square tests to identify patterns, themes, and relationships within the data. Nearly all (>95%) respondents owned livestock while substantially more rural farmers (81%) than urban farmers (35%) engaged in crop production. Drought was perceived by a sizeable proportion (>70%) of small-scale farmers as a very serious environmental challenge with adverse socio-economic repercussions on land-based activities. Livestock losses and crop failure were the key impacts reported by small-scale farmers in both rural and urban settings. About 86% of respondents across the sample reported declines in crop yields, with significantly more farmers in rural sites (45%) than urban sites (31%) reporting so. A substantial proportion of farmers across the sample (93%) reported drought response strategies relating to livestock and crop production, such as changing of farming practices, use of drought-resistant crops and government support, with slight differences in the proportion of farmers reporting so between urban (89 %) and rural (95 %) sites. Concerning government support, most respondents (>70%) stated that they were dissatisfied, with slightly more respondents in urban areas (77%) than in rural (70%) areas reporting so. Overall, the results of this study suggest a minimal response capacity of small-scale farmers to droughts in both rural and urban settings due to socio-economic and administrative factors, which calls for the need for drought-response strategies to build adaptive capacity for small-scale farmers. Turning to close cooperation between different stakeholders, such as local farmers, government officials, practitioners, and scientists might allow co-production of knowledge needed to inform drought response strategies. In some instances, attention needs to be given to farmers who are more vulnerable than others. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-10-13