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Managing releases of Anagyrus vladimiri (Triapitsyn) to augment biocontrol of the citrus mealybug Planococcus citri (Risso) in South African citrus orchards

  • Authors: Mommsen, Wayne Trevor
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/434952 , vital:73118
  • Description: In May 2019, South Korean inspectors rejected numerous grapefruit consignments from Letsitele, Hoedspruit and Onderberg in South Arica, because of live mealybug found on fruit. Growers expressed deep concern as mealybug management to a phytosanitary level was almost unattainable. Regular spray interventions for control of citrus black spot fungus, Phyllosticta citricarpa, and citrus thrips, Scirtothrips aurantii, cause repercussions in mealybug populations because they undermine the naturally occurring biocontrol complex. As part of an Integrated Pest Management (IPM) strategy, release of commercially produced parasitoids is common practice, to augment the naturally occurring beneficial insect populations. Prior knowledge of the harmful effects of insecticides on parasitoids is essential to IPM planning and the success of the biocontrol component in such a programme. Timing of augmentative releases to coincide with the phenology of citrus and the mealybug pest is also considered important for the successful establishment and control. Consequently, field trials were conducted to compare efficacy of early vs. late releases of Anagyrus vladimiri (Triapitsyn), an effective parasitoid of the citrus mealybug, Planococcus citri (Risso). Semi-field bioassays were conducted concurrently to determine the impact of various thripicides on A. vladimiri. The impact of sulfoxaflor, spinetoram, spirotetramat and prothiofos were rated harmless, as A. vladimiri mortality was lower than 25% after coming into contact with aged residues between 7 and 14 days old. October and November releases of A. vladimiri resulted in early parasitism and lowered peak-infestation of mealybug. January releases are possibly too late in grapefruit and lemon, open field, orchards, considering parasitism by A. vladimiri peaked in February. In mandarin orchards under net, percentage parasitism of 3rd instar mealybug increased a month later. Notably, at harvest, the difference in efficacy between treatments was not clear. This could be explained by high levels of natural parasitism observed in the treated and untreated orchards, which emphasises the importance of conservation biocontrol. In a second season, the proportion of hyperparasitoids captured (61%) from samples of mealybug-infested fruit was larger than the proportion of primary parasitoids, Anagyrus vladimiri, Coccidoxenoides perminutus (Girault) and Leptomastix dactylopii (Howard) (39%), which was far lower than the captures of eclosing primary parasitoids the previous season, which was 60%. The new discovery of Pseudaphycus sp. in citrus orchards in South Africa could be a key in explaining the uncontrollable levels of mealybug experienced and has drawn attention to a need for further understanding of ecological factors that influence biological control in citrus. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2024
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  • Date Issued: 2024-04-04

MeerKAT observations of the Abell 141 galaxy cluster

  • Authors: Stanbury, Savannah Mae
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435378 , vital:73152
  • Description: This study is aimed at being an overview and investigation of the behaviour and morphology of radio quiet (RQ) active galactic nuclei (AGN) in the radio and optical/near-infrared (NIR) bands. It is hoped that a concise description of the relation that exists between accretion activity and star formation (SF) will be achieved through utilization of multiwavelength astronomy analysis. This analysis includes the processing of data acquired from the MeerKAT International GHz Tiered Extragalactic Exploration survey (MIGHTEE), the Southern African Large Telescope (SALT), the Hyper Suprime Camera (HSC) mounted on the Subaru telescope and the VISTA telescope. In this thesis, several targets were observed using SALT spectroscopy, but a redshift of only one of them was obtained. Lastly, it was established that for the sample of RQ AGN studied, the AGN contribute a large fraction of the radio emission observed. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2024
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  • Date Issued: 2024-04-04

Paul and the soul: an analysis of the Apostle’s anthropology

  • Authors: Pluke, Dylan Hay
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435506 , vital:73164
  • Description: It may be no exaggeration to say that every aspect of the Apostle Paul’s thought is debated. This is certainly the case for his anthropology, which is to say his beliefs regarding the nature of the human person. There is intense debate concerning what Paul believed about the human person. This is especially so when arguing about whether or not Paul believed in a human soul. In the thesis that follows, I use a linguistic analysis of Paul’s writings as well as those of two of his putative backgrounds, to determine what he believed regarding the nature of the human soul. The results of this analysis are that, of the potential backgrounds that may have influenced the Apostle, the Jewish background into which he was born is the most pertinent, and that neither of the two words that Paul uses mean soul, in the sense of something which is immaterial and survives death. Rather, the psyche refers to one’s life, and the pneuma to the part of the person that connects one with God and which will replace the psyche and animate the person in the new age to come. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2024
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  • Date Issued: 2024-04-04

Perceptions of registered counselors’ ability to process clients’ narrated dreams during counselling

  • Authors: Mpondo, Nontutuzelo
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435468 , vital:73160
  • Description: Research related to South African registered counsellors (RCs) have yet to show how RCs incorporate dreamwork in their counselling sessions. Dreamwork has largely been relegated to the periphery of clinical psychological practice, posing a challenge as clients on other levels of counselling practice bring dream material to mental health practitioners often lacking confidence and competence to respond effectively to this material. Clients' discussion of dreams can be beneficial in the counselling process. However, there appears to be a gap in educational opportunities for practitioners to develop skills and competency in working with dreams. This study's objective was to contribute to the sparse research material in this area. A qualitative research approach with an exploratory design using semi-structured interviews was used to explore and understand the meaning RCs ascribed to their work with dreams and clients. Purposive sampling was used to recruit 5 participants. Social constructionism was used as a theoretical framework for understanding and interpreting the data, and the data was analysed using thematic analysis. This knowledge is geared towards providing insight into what extent university or college curriculum covered content related to dreams, dreamwork, dream theories, and dream models, and to what extent RC's training prepared them to provide essential primary psychological services related to distress arising from dreams. This research highlighted how RCs engaged and perceived their competency with dream material. This study also highlighted that RCs were interested in dreamwork training and believed it would enhance their confidence and effectiveness in working with dream material during their sessions. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
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  • Date Issued: 2024-04-04

Performance evaluation of baseline-dependent window functions with several weighing functions

  • Authors: Vanqa, Kamvulethu
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435850 , vital:73206
  • Description: Radio interferometric data volume is exponentially increasing with the potential to cause slow processing and data storage issues for radio observations recorded at high time and frequency resolutions. This necessitates that a sort of data compression is imposed. The conventional method to compress the data is averaging across time and frequency. However, this results in amplitude loss and source distortion at the edges of the field of view. To reduce amplitude loss and source distortion, baseline-dependent window functions (BDWFs) are proposed in theliterature. BDWFs are visibility data compression methods using window functions to retainthe signals within a field of interest (FoI) and to suppress signals outside this FoI. However,BDWFs are used with window functions as discussed in the signal processing field without any optimisation. This thesis evaluates the performance of BDWFs and then proposes to use machine learning with gradient descent to optimize the window functions employed in BDWFs. Results show that the convergence of the objective function is limited due to the band-limited nature of the window functions in the Fourier space. BDWFs performance is also investigated and discussed using several weighting schemes. Results show that there exists an optimal parameter tuning (not necessarily unique) that suggests an optimal combination of BDWFs and density sampling. With this, ∼ 4 % smearing is observed within the FoI, and ∼ 80 % source suppression is achieved outside the FoI using the MeerKAT telescope at 1.4 GHz, sampled at 1 s and 184.3 kHz then averaged with BDWFs to achieve a compression factor of 4 in time and 3 in frequency. , Thesis (MA) -- Faculty of Science, Mathematics, 2024
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  • Date Issued: 2024-04-04

Political competition and local government debt: implications for human development: A case study of Eastern Cape municipalities

  • Authors: Matapuri, Fadzai Valerie
  • Date: 2024-04-04
  • Subjects: Local government South Africa Eastern Cape , Municipal finance South Africa Eastern Cape , Public administration South Africa Eastern Cape , Municipal services South Africa Eastern Cape , Electoral competition , Human development
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435874 , vital:73208
  • Description: South African Municipalities are currently in a precarious financial situation. The financial distress has intensified so much that local governments are on the brink of collapse. Municipalities in South Africa currently owe over 35.5 billion rands. Reports from the Auditor-General of South Africa portrayed a grim picture of the state of financial affairs in municipalities; only 33 municipalities out of 278 had received a clean audit, with over 30 billion rands in expenditure declared irregular. The report further revealed that there were numerous cases of non-compliance with key legislation in municipalities. The poor financial audits across the country have stressed the severe lack of accountability, government issues and political turmoil. Due to this state of affairs, municipalities cannot deliver services such as sanitation, electricity, and water. As a result, many service delivery protests have occurred over the years. Political factors have been highlighted as the leading cause of these local government woes. This study aims to investigate the relationship between political competition and local government debt and its effect on human development in Eastern Cape municipalities. The study used a panel data set for 32 municipalities and electoral data from 2009 to 2016. The panel vector autoregression model, generalized least squares, fixed and random effects methods were used to investigate the relationship between political competition and local government debt. The study found a positive unidirectional relationship between political competition and local debt. This was found using the normalized Herfindahl index, debt to asset, tress index, human development index, population and poverty variables. Moreover, estimated results showed that local governments in the eastern cape were characterised by a political monopoly that, in turn, increased local government debt through growth-hindering policies adopted by political leaders. Resulting in economic concentration, which hinders local economic growth and human development. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
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  • Date Issued: 2024-04-04

Social justice implications of the language of the court judgment genre and its development in pre- and post-independence Zimbabwe

  • Authors: Nemaramba, Dylan
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/435605 , vital:73172
  • Description: Access restricted. Expected release in 2026. , Thesis (PhD) -- Humanities, Linguistics and Applied Language Studies, 2024
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  • Date Issued: 2024-04-04

The effect of Gracilaria gracilis (Rhodophyta) on growth and behaviour of farmed abalone Haliotis midae when included in the abalone diet

  • Authors: Madlala, Njabulo Praiseworth
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435332 , vital:73148
  • Description: Abalone feed naturally on algae, but commercial abalone farms rely on formulated feed. The inclusion of algae with the formulated feed in the diet improves growth, health and feed conversion ratio (FCR). However, the kelp that is currently included in the feed is wild harvested and this resource is limited and under increasing pressure. Thus, there is a need to develop an alternative sustainable source of algae. The aim was to use Gracilaria gracilis algae (that was produced with mussel in an integrated multitrophic aquaculture system; IMTA) which was then included into abalone feeds and its influence on abalone growth, FCR and behaviour was evaluated. Sea-based G. gracilis was harvested off an existing IMTA system, manufactured into Abfeed® and fed to abalone to determine growth efficiency. Abalone (30 - 40 g abalone-1) originated from the same cohort at Whale Rock Abalone Farm (Pty) Ltd., Hermanus. Abalone were fed either: Abfeed® S34 only with no algae (G0, the control); Abfeed® with sea-based IMTA G. gracilis included in the formulated feed at 0.75 % (G0.75); 1.50 % (G1.50); 3.00 % (G3.00); 6.00 % (G6.00); and 12.00 % (G12.00) inclusion; and Abfeed® S34 with fresh-live G. gracilis (cultured at Whale Rock Abalone Farm (Pty) Ltd.; Gfresh + S34s). Abalone shell length, whole body mass and FCR were measured at a four-months interval over eight months (two growth cycles). Differences in behaviour (i.e., level of activity and feeding activity) were also monitored and comparing between treatments. There was significant difference in mean whole-body mass between treatments (RMANOVA, F(6, 29) = 3.71, p = 0.007). Abalone fed the diet with the highest inclusion of dry G. gracilis (G12.00) had a lower mean whole-body mass value (74.13 ± 2.94 g abalone-1) than abalone from all the other diets after eight months. There was a negative relationship between the condition factor and dry G. gracilis inclusion rate for the first growth cycle (y = - 0.0044x + 1.222, R2 = 0.24, p=0.009) and second-growth cycle (y = - 0.0096x + 1.2233, R2 = 0.51, p = 0.00002). Abalone receiving fresh G. gracilis were less quiescent and more alert on the first hours after food distribution (p < 0.05). The same proportion of abalone with G0, G0.75, and G6.00 G. gracilis inclusion were feeding all along the 9 hours post-feeding. This study will potentially reduce the dependence of abalone farms on wild-harvested kelp in formulated feed. This will improve their contribution to a more environmentally sustainable global production of sea food products, making them more competitive on international markets. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2024
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  • Date Issued: 2024-04-04

The feasibility of task-shifting prolonged exposure for Primary Care (PE-PC) for PTSD within a low resource community in the Eastern Cape

  • Authors: Shabangu, Princess Noxolo Nonhlanhla
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435479 , vital:73161
  • Description: Although high levels of trauma exposure potentiate an alarming prevalence of PTSD, increasing the need for trauma-focused treatment, the South African health system is unable to care for the population. The South African healthcare system contains a range of systemic and structural inefficiencies, including suboptimal care and shortages of healthcare professionals. PE-PC offers a resource-constrained mental healthcare system solution by integrating an evidence-based intervention (EBI) in primary care settings. Likewise, the present study acknowledges the ratio of mental healthcare professionals to patients in low- and middle-income countries (LMIC). It explores task shifting to expand mental healthcare to primary care settings. The study follows qualitative healthcare design research to explore the experiences and perceptions of the two cohorts of trauma support workers (TSW) from Rhode University and the Joza community in Makhanda. The feasibility of the PE-PC intervention in Makhanda was illustrated through the data obtained from the TSWs' experiences and perceptions of the intervention's utility. The present study presents an essential contribution to the sparse research conducted on treating PTSD in LMIC with shortages in healthcare professionals. The thematic findings look at the trauma support workers (TSWs) role, including some of its challenges, to explore the feasibility of interventions. Some of the themes highlighted unpack the perceived utility of task-shifting in low-resource contexts, the limitations thereof and considerations for future research. Notwithstanding the challenges, the data from the present study indicates that PE-PC can be feasibly task-shifted in low-resource contexts such as Makhanda. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
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  • Date Issued: 2024-04-04

The mediating role of generational difference on the relationship between psychological capital, psychological empowerment, organisational support and the wellbeing of South African National Defence Force members

  • Authors: Selepe, Babitsanang Annah
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/435616 , vital:73173 , DOI 10.21504/10962/435616
  • Description: There is a growing concern in understanding the contribution of generational difference (as a mediating variable) and factors that increase soldiers' well-being. This study aimed to determine the relationship between Psychological Capital, Psychological Empowerment and Organisational Support, and well-being. Additionally, it proposes the generational differences as a potential mediating factor among these variables. The study was guided by a positivist philosophy and quantitative research method was employed. The sample for this research consisted of 777 members from both Internal deployed within borders of Free state and those going for external deployment at De-Brug. The results show most respondents were male (78.3%) and 21.7% female. Most respondents were categorised as Gen Y (between 1981 - 1996, 67.0%), followed by Gen X (1965 - 1980, 24.8%) and Gen Z (1997 - 2012, 8.2%). Most respondents were in the SA Army, followed by SAAF and SAMHS and the SA Navy. Spearman’s Correlation and ANOVA analyses were conducted to test the relationship between the variables. The results revealed significant relationships between the variables included in the empirical model. However, Well-being does not have a statistically significant correlation with the mediation variable, generation cohort. Similarly, generation cohorts (X, Y, Z) do not significantly correlate with the predictor variables, Perceived Organisational Support, Psychological Empowerment. However, there is a statistically significant small negative correlation between generation cohort (Age) and Psychological Capital. The multiple regression analysis exhibited a significant overall model fit, indicating that 30% of the variance in employee well-being was accounted for by the predictors. Thus, this research implicates that the South African National Defence Force (SANDF) would benefit from developing a culture and adopting policies as well as programmes that prioritises psychological well-being above physical prowess. For this reason, the present study is regarded as offering a potentially valuable contribution to the existing body of research in the positive psychology and reveals practical implications and applications within the military context. The study recommends that combat readiness requires prioritising mental health above physical strength. Policymakers should consider psychological factors like psychological capital and psychological 6 empowerment. Training programmes should include Psychological Capital and cognitive resilience. There should also be further research on positive psychology and troops' well-being. These factors can help improve peacekeeping and combat force readiness. Understanding generational variations' mediating effect can inform resilience and training programmes. Military organisations should cultivate confident, capable, and educated leaders to improve military proficiency. , Thesis (PhD) -- Humanities, Psychology, 2024
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  • Date Issued: 2024-04-04

The use of gabions as a tool for ecological engineering

  • Authors: Seath, Jessica Lauren
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/434987 , vital:73121
  • Description: Anthropogenic activities are centred in coastal ecosystems, including the development of harbours and/or marinas. The artificial structures used in coastal development typically has a different composition, orientation and level of complexity to that of natural ecosystems contributing to loss of biodiversity and increased incidence of invasive species. Ecological engineering research is attempting to identify different types of structures and materials that can increase species diversity and target species of conservation concern in coastal systems. The aim of this study was to investigate the efficacy of gabions (rock filled structures) as an ecological engineering tool by comparing community structure on these structures with pre-existing seawall structures within a small harbour and marina in South Africa (Knysna Harbour). The objectives of the study were to compare the differences in; 1) fish and; 2) colonising organisms’ diversity and composition between two artificial structures. Thirteen gabion boxes were deployed in Knysna Harbour and together with corresponding seawalls, monitored quarterly over a period of 12 months (August 2020 – August 2021) to assess taxon and functional richness, diversity, abundance and composition of fish, invertebrate and algal species. Physico-chemical characteristics of the water body were also monitored quarterly. Remote underwater video systems were used to quantify MaxN (maximum number of a fish species in the frame at any one time during each set that gives an indication of relative abundance) and identify fish species. The results of the two-way crossed ANOVAs indicated that gabion habitats recruited greater numbers and more types of fish species and from more functional groups than the seawalls, especially omnivorous and carnivorous fish. Additionally, photoquadrats were used to quantify percentage cover, counts and to identify colonising taxa. The results of the two-way crossed ANOVAs indicated that gabions hosted greater numbers of species resulting in a higher overall diversity and abundance of colonising organisms than seawalls. By contrast, the seawalls supported more types of functional groups of colonising organisms than gabions, largely due to abundances of different algal species. The results from the crossed PERMANOVAs indicated that the composition of fish and colonising organisms were vastly different from one another, and that each habitat was supporting very different functional groups. Results indicate that whilst both gabions and seawalls contain several alien species, that the ratio of native to alien species is higher in gabion habitats. Additionally, this research observed that gabion structures hosted four species listed on the IUCN Red List of Threatened Species. This study has highlighted that the use of gabions (with their natural increased complexity) could be important to consider for the future of urban coastal development in harbours such as in Knysna Harbour. Ecological engineering projects using gabions have the potential to be used in South Africa in projects that aim at increasing biodiversity in urban coastal environments. As well as increasing the settlement and abundance of habitat-forming ecosystem engineers to ensure the long-term stability of these ecosystems. They can be used both in the development of new costal development projects as well as in an ad-hoc fashion where they can be interspersed on seawalls in harbours. Additionally, gabions have the potential to be used in projects that target species of conservation concern such as the endangered Knysna Seahorse (Hippocampus capensis). It is, however, important to monitor the invasion by non-native species in future ecological engineering projects in South Africa as well as their potential for creating ecological traps (a situation in which an organism may be convinced to settle in a low-quality habitat) for certain species. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2024
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  • Date Issued: 2024-04-04

The “Inadequately Married”: extending the putative marriage doctrine to assist vulnerable parties in invalid customary marriages

  • Authors: Mavindidze, Tafadzwa Naomi
  • Date: 2024-04-04
  • Subjects: Customary law South Africa , Marriage law South Africa , Women Legal status, laws, etc. South Africa , Polygamy Law and legislation South Africa , Putative marriage , Recognition of Customary Marriages Act, 1998
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/434839 , vital:73109
  • Description: This thesis considers whether the putative marriage doctrine can be developed to assist parties that find themselves in invalid customary marriages. The thesis focuses on situations where a customary marriage is considered invalid in circumstances where a party does not meet specific legislative or customary requirements. In most instances, these women are left without protection and regulation of the proprietary consequences of the so-called marital estate. The research considers the putative marriage doctrine as a remedy to this challenge. The doctrine is utilised where one or both parties believe in good faith that their marriage is valid when, in fact, one or more of the material requirements for marriage have not been met. Currently, the judgment of Zulu v Zulu 2008 (4) SA 12 (D) impedes the doctrine’s application in polygamous customary marriages and thus impedes its use by women who are found in invalid customary marriages. The research carries out a comparative analysis of Californian and Namibian family law, in order to consider how other jurisdictions deal with similar situations. The thesis further proposes a framework to develop the putative marriage doctrine in a way that ensures the protection of customary wives in subsequent marriages that are declared invalid. , Thesis (LLM) -- Faculty of Law, Law, 2024
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  • Date Issued: 2024-04-04

To yoga or not to yoga? The effect of yoga on sustained attention: an fNIRS Study

  • Authors: Cunningham, Cornelia
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435411 , vital:73155
  • Description: Deficits in sustained attention are ubiquitous across numerous neuropsychological disorders. Besides being critical in learning, memory, and general cognitive capacity, sustained attention is thought to be the primary foundation for ‘higher’ cognitive functions including, divided, selective, and focused attention. Despite the above, sustained attention remains the lesser-researched form of attention. Sustained attention is thought to be regulated by the default mode network and the central executive network, the latter of which is situated in the dorsolateral prefrontal cortex (DLPFC), a brain region typically associated with sustained attention. Given the contributions of sustained attention in overall cognitive functioning, alternative and natural methods used to enhance this type of executive function are important. One alternative method is yoga exercise, where yoga is thought to place the body into the most favourable state to enhance sustained attention capacity. This study found a significant (p = 0.018) difference between the yoga and control group in incongruent response accuracy scores in the SCWT. However, no statistically significant differences (p < 0.05) were observed in fNIRS individual and group analyses, SCWT congruent and incongruent reaction time, as well as congruent response accuracy. This suggests that short-term yoga practice may improve behavioural markers for sustained attention, at least in terms of cognitive interference. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
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  • Date Issued: 2024-04-04

Towards a possible future solution against Multidrug Resistance: An in silico exploration of the Multidrug and Toxic compound Extrusion (MATE) transporter proteins as potential antimicrobial drug targets

  • Authors: Damji, Amira Mahamood
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435009 , vital:73123
  • Description: The rise of multidrug resistance (MDR) has become a pressing global issue, hindering the treatment of cancers and infectious diseases, and imposing a burden on healthcare systems and the economy. The Multidrug and Toxic compound Extrusion (MATE) superfamily of membrane efflux transporters is one of the key players contributing to MDR due to their ability to export a wide range of cationic and hydrophilic xenobiotics, including treatment drugs, from cells, diminishing their efficacy. Targeting MATE transporters holds great promise in achieving some cellular control over MDR, but first, a deeper understanding of their structure-function-dynamics link is required. This study aimed to explore the MATE transporters as potential antimicrobial drug targets using a two-fold in silico approach. First, virtual screening of compounds from the South African Natural Compounds Database (SANCDB) was performed to identify prospective lead inhibitory compounds against the MATE transporters using molecular docking, and top hits were selected based on their binding energy and interaction with the active site on the N-lobe of the protein. Second, to investigate the molecular-level dynamics of their extrusion mechanism, the MATE transporter structures were embedded in a POPC membrane bilayer using the CHARMM-GUI online tool and then subjected to MD simulations for 100 ns with the CHARMM 36m force field using GROMACS. The resulting trajectories were evaluated using three standard metrics – RMSD, RMSF, and Rg; significant global structural changes were observed and key functional regions in both membrane- and non-membrane transmembrane (TM) segments were identified, containing more dynamic and flexible residues than other regions. Furthermore, the MATE transporters showed more of a loosely-packed structure, providing flexibility to allow for conformational switching during their substrate-transport cycle, which is typical for proteins whose secondary structures are composed of all α-helices. The scope of this study lied in the preliminary stages of the computer-aided drug design process, and provided insights that can be used to guide the development of strategies aimed at regulating or inhibiting the function of the MATE transporters, offering a possible future solution to the growing challenge of MDR. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2024
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  • Date Issued: 2024-04-04

Towards an artificial intelligence-based agent for characterising the organisation of primes

  • Authors: Oyetunji, Nicole Armlade
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435389 , vital:73153
  • Description: Machine learning has experienced significant growth in recent decades, driven by advancements in computational power and data storage. One of the applications of machine learning is in the field of number theory. Prime numbers hold significant importance in mathematics and its applications, for example in cryptography, owing to their distinct properties. Therefore, it is crucial to efficiently obtain the complete list of primes below a given threshold, with low relatively computational cost. This study extensively explores a deterministic scheme, proposed by Hawing and Okouma (2016), that is centered around Consecutive Composite Odd Numbers, showing the link between these numbers and prime numbers by examining their internal structure. The main objective of this dissertation is to develop two main artificial intelligence agents capable of learning and recognizing patterns within a list of consecutive composite odd numbers. To achieve this, the mathematical foundations of the deterministic scheme are used to generate a dataset of consecutive composite odd numbers. This dataset is further transformed into a dataset of differences to simplify the prediction problem. A literature review is conducted which encompasses research from the domains of machine learning and deep learning. Two main machine learning algorithms are implemented along with their variations, Long Short-Term Memory Networks and Error Correction Neural Networks. These models are trained independently on two separate but related datasets, the dataset of consecutive composite odd numbers and the dataset of differences between those numbers. The evaluation of these models includes relevant metrics, for example, Root Mean Square Error, Mean Absolute Percentage Error, Theil U coefficient, and Directional Accuracy. Through a comparative analysis, the study identifies the top-performing 3 models, with a particular emphasis on accuracy and computational efficiency. The results indicate that the LSTM model, when trained on difference data and coupled with exponential smoothing, displays superior performance as the most accurate model overall. It achieves a RMSE of 0.08, which significantly outperforms the dataset’s standard deviation of 0.42. This model exceeds the performance of basic estimator models, implying that a data-driven approach utilizing machine learning techniques can provide valuable insights in the field of number theory. The second best model, the ECNN trained on difference data combined with exponential smoothing, achieves an RMSE of 0.28. However, it is worth mentioning that this model is the most computationally efficient, being 32 times faster than the LSTM model. , Thesis (MSc) -- Faculty of Science, Mathematics, 2024
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  • Date Issued: 2024-04-04

“COVID-19 made me a single parent”: an interpretative phenomenological analysis of a woman’s perinatal experiences during the COVID-19 pandemic

  • Authors: Hadebe, Asanda Locresia
  • Date: 2024-04-04
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/435437 , vital:73158
  • Description: The COVID-19 pandemic resulted in unprecedented challenges across various aspects of life. In particular, pregnant women encountered unique challenges and circumstances that necessitated adaptation to the experience of the perinatal period1 Satyanarayana et al., (2011). A considerable amount of research has been conducted regarding women's experience of the perinatal period during COVID-19, especially in first world countries. However, inadequate research has been done in the South African context and specifically, there is a lack of qualitative research providing thick descriptions of experience. The analysis describes three master themes supported by subordinate themes. The main themes are (1) A sense of loss and change, (2) Managing COVID-19 and its regulations during the perinatal period, and (3) Glimmers of hope and desirable aftermaths. The study’s findings expand and support the growing literature of women’s experiences on the perinatal period during the COVID-19 pandemic. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
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  • Date Issued: 2024-04-04

A comparative analysis of land, labour and gender in a communal area and fast track farm in Zvimba Rural District, Zimbabwe

  • Authors: Chinomona, Perpetua
  • Date: 2024-04-03
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/434612 , vital:73089 , DOI 10.21504/10962/434612
  • Description: This thesis provides a comparative analysis of gender, land, and labour between two different types of farming sites in rural Zimbabwe, namely long-established communal areas and the more recent Al fast track land reform resettlement areas. More specifically, the focus is on Kanzou Village and Stratford fast track resettlement farm respectively, located in Zvimba District in Mashonaland West Province. The study focuses on the period from the year 2000, the year in which the fast track resettlement programme was launched by the government. The thesis examines in particular the status and experience of women with regard to land acquisition, access and security as well as the division of labour (including assets, inputs and labour-time) in the spheres of production (i.e., agriculture) and social reproduction (i.e., the domestic sphere). This includes highlighting the power relations existing between men and women in both spheres, in the light of prevailing systems of patriarchy. Analytically, the thesis is framed in terms of feminism, drawing upon the complementary insights of Third World feminism and socialist feminism. In seeking to capture the perspectives and practices of men and women in the two sites, the fieldwork for the study entails a qualitative methodology. The findings of the research demonstrate the existence and relevance of patriarchal systems with respect to land and labour in Kanzou Village and Stratford fast track farm, with key commonalities appearing across the two sites with reference to the multiple ways in which women are disadvantaged and disempowered. Therefore, gender bias and inequality in land and labour are exhibited by the fact that men have, for instance, easier access to land, less involvement in labouring activities, control over a higher proportion of household income and a disproportionate level of power in the household. At the same time, there are certain differences between Kanzou Village and Stratford fast track farm around questions of gender, land and labour, but these are differences in degree rather than kind. Perhaps more important in explaining the differences between the two sites, and indeed differences within each site, are other variables. These variables include marital status, form or marriage (for example, customary or civil marriages), age and gender. By considering these variables as well, the thesis shows the importance of unpacking the notion of ‘woman’ to reveal the variegated and differential experiences of different categories of women in rural Zimbabwe. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2023
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  • Date Issued: 2024-04-03

A critical analysis of the factors influencing knowledge sharing in Indian family owned businesses in South Africa

  • Authors: Sha, Shafeek
  • Date: 2024-04-03
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Doctoral theses , text
  • Identifier: http://hdl.handle.net/10962/434817 , vital:73107 , DOI 10.21504/10962/434817
  • Description: It is commonly believed that family businesses have formed the backbone of many economies around the globe and that they have been the predominant form of enterprise that has given rise to some of the most famous multinational enterprises. Family businesses contribute to the wealth creation in most economies and conservative estimates suggest that 65% to 80% of all businesses worldwide are owned and managed by families. In South Africa, Indian family owned businesses contribute more to employment than any other family business. There is a general perception amongst South Africans that Indian family owned businesses are more successful and that this success is continued from one generation to the next. Intrigued by this “phenomenon” for many years, the researcher decided to investigate it. The perspective adopted for this research was to look at the research problem from a knowledge management discipline viewpoint, in general, with a specific focus on knowledge sharing and Indian family owned businesses. The purpose of this study is to critically analyse the factors that influence the effectiveness of knowledge sharing in Indian family owned businesses. So the research answered the question: How do Indian family owned businesses in South Africa share their knowledge to ensure the continued success of their businesses through succeeding generations? A positivist research paradigm and philosophy was adopted for this research together with a quantitative research approach using survey research as the research strategy of choice. After conducting an extensive literature review, the next step was to develop and formulate a theoretical model, and flowing from the model and prior research, a research instrument was developed and administered to a qualifying sample of Indian family owned businesses in South Africa. Structural equation modelling was used as the principal mode of statistical analysis to measure the relationships amongst the variables in the model proposed in this study. After analysing the empirical data, the following key factors were identified as statistically significant in being determinants of knowledge sharing in Indian family owned businesses in South Africa: organisational culture, learning organisation, and leadership. These findings serve to contribute to the existing literature within the fields of knowledge management and family business. This study will richly contribute to research-based evidence of the factors that influence knowledge sharing in Indian family owned businesses. The outcomes will allow existing and emerging family businesses to ensure the future success of their enterprises from one generation to the next by embracing the empirical findings of this research and thus ultimately contribute to the future success of the family business as a whole. , Thesis (PhD) -- Faculty of Commerce, Management, 2024
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  • Date Issued: 2024-04-03

An exploratory study of leadership and organisational change through the lens of organisational behaviour: a secondary school in Makhanda

  • Authors: Yedwa, Sesonasipho
  • Date: 2024-04-03
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/434595 , vital:73088
  • Description: Access restricted. Expected release in 2025. , Thesis (MSocSci) -- Faculty of Humanities, Sociology, 2024
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  • Date Issued: 2024-04-03

Capital mobility and economic growth in South Africa

  • Authors: Dhlamini, Nonceba Michelle
  • Date: 2024-04-03
  • Subjects: Uncatalogued
  • Language: English
  • Type: Academic theses , Master's theses , text
  • Identifier: http://hdl.handle.net/10962/434712 , vital:73098
  • Description: The South African current account balance has been deteriorating over the years. An investigation of the correlation between capital mobility and economic growth is of interest as South Africa is heavily reliant on capital inflows to finance the current account deficit. This research topic is of importance as there is need to devise policies that maximise the benefits the nation derives from capital mobility. The benefits that capital flows provide economies, theoretically outweigh the disadvantages, provided that capital flows are absorbed productively. The topic is also of interest in the light of the magnitude of shocks to the South African economy such as the rand crisis, dotcom bubble, stock market bubble, inflation targeting, commodity super cycle, global financial crisis, the Covid-19 pandemic and Russo-Ukrainian War, as these shocks have translated to slower economic growth and higher levels of inflation. These shocks have equally revealed that countries need to have sound macroeconomic policies in order to survive the impact of any crises. The vision 2030 secretariat has identified capital markets as the key providers of capital required for achieving social economic blueprint. The empirical evidence locally is limited in comparison to the empirical evidence from outside of South Africa. This topic is of importance as South African studies on this topic are not as recent and this study aims to bridge that gap. Data were obtained from the South African Reserve Bank Quarterly Bulletin and the World Bank database for the period 1990 to 2022. The Autoregressive Distribution Lag model was employed in order to determine the relationship. This study relied on the supply-leading theory which posits capital markets may positively or negatively affect key indicators of economic growth. The study found that there is a positive long run relationship between net capital flows, saving-investment ratio and economic growth and a negative long run relationship between the degree of trade openness and economic growth. The findings will allow opportunity to address capital flow surges and in turn boost investor confidence. Capital flow management measures can help manage destabilizing exchange rate movements and capital flows coupled with macroprudential tools helping reduce the domestic buildup of vulnerabilities. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
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  • Date Issued: 2024-04-03
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