Natural Language Processing with machine learning for anomaly detection on system call logs
- Authors: Goosen, Christo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424699 , vital:72176
- Description: Host intrusion detection systems and machine learning have been studied for many years especially on datasets like KDD99. Current research and systems are focused on low training and processing complex problems such as system call returns, which lack the system call arguments and potential traces of exploits run against a system. With respect to malware and vulnerabilities, signatures are relied upon, and the potential for natural language processing of the resulting logs and system call traces needs further experimentation. This research looks at unstructured raw system call traces from x86_64 bit GNU Linux operating systems with natural language processing and supervised and unsupervised machine learning techniques to identify current and unseen threats. The research explores whether these tools are within the skill set of information security professionals, or require data science professionals. The research makes use of an academic and modern system call dataset from Leipzig University and applies two machine learning models based on decision trees. Random Forest as the supervised algorithm is compared to the unsupervised Isolation Forest algorithm for this research, with each experiment repeated after hyper-parameter tuning. The research finds conclusive evidence that the Isolation Forest Tree algorithm is effective, when paired with a Principal Component Analysis, in identifying anomalies in the modern Leipzig Intrusion Detection Data Set (LID-DS) dataset combined with samples of executed malware from the Virus Total Academic dataset. The base or default model parameters produce sub-optimal results, whereas using a hyper-parameter tuning technique increases the accuracy to within promising levels for anomaly and potential zero day detection. , Thesis (MSc) -- Faculty of Science, Computer Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Goosen, Christo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424699 , vital:72176
- Description: Host intrusion detection systems and machine learning have been studied for many years especially on datasets like KDD99. Current research and systems are focused on low training and processing complex problems such as system call returns, which lack the system call arguments and potential traces of exploits run against a system. With respect to malware and vulnerabilities, signatures are relied upon, and the potential for natural language processing of the resulting logs and system call traces needs further experimentation. This research looks at unstructured raw system call traces from x86_64 bit GNU Linux operating systems with natural language processing and supervised and unsupervised machine learning techniques to identify current and unseen threats. The research explores whether these tools are within the skill set of information security professionals, or require data science professionals. The research makes use of an academic and modern system call dataset from Leipzig University and applies two machine learning models based on decision trees. Random Forest as the supervised algorithm is compared to the unsupervised Isolation Forest algorithm for this research, with each experiment repeated after hyper-parameter tuning. The research finds conclusive evidence that the Isolation Forest Tree algorithm is effective, when paired with a Principal Component Analysis, in identifying anomalies in the modern Leipzig Intrusion Detection Data Set (LID-DS) dataset combined with samples of executed malware from the Virus Total Academic dataset. The base or default model parameters produce sub-optimal results, whereas using a hyper-parameter tuning technique increases the accuracy to within promising levels for anomaly and potential zero day detection. , Thesis (MSc) -- Faculty of Science, Computer Science, 2023
- Full Text:
- 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
- Full Text:
- Date Issued: 2023-10-13
- 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
- Full Text:
- Date Issued: 2023-10-13
Marine plastic pollution impacts on ecosystem services and livelihoods in South Africa: a review and stakeholder perceptions
- Authors: Yose, Papama
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424743 , vital:72180
- Description: Marine plastic pollution is one of the major environmental problems globally, with adverse impacts on marine ecosystem services, functions and benefits and people. Yet, compared to plastic pollution impacts on terrestrial ecosystems, the impacts of plastic waste on marine ecosystems are little studied and poorly understood in South Africa. In response, research interest on the ecological and economic impacts of marine plastic pollution has grown rapidly but socio-cultural impacts remain poorly conceptualized and little understudied. This trend is arguably driven by the dominance of a quantitative paradigm which is arguably inadequate to respond to dynamic socio-cultural issues and contexts. Further, in South Africa, marine ecosystems are used by diverse groups of people ranging from subsistence users, tourism operators, commercial fishers and recreational users, meaning that addressing marine plastic pollution requires a multi-stakeholder approach. However, few studies explore the perceptions of diverse stakeholders regarding marine plastic pollution, its impacts and potential interventions. Against this background, the objective of the thesis are twofold: (a) to argue for a more nuanced understanding of marine plastic pollution impacts on human well-being in order to strengthen conceptualization of impacts that goes beyond direct and quantitatively measured impacts (ecological, health and economic) but considers the socio-cultural dimensions of impacts (lifestyle disruptions, mental health costs and cultural and heritage impacts), and (b) examine stakeholders’ perceptions of marine plastic pollution, its impacts and potential interventions in South Africa. Drawing on case studies, this study provides a working definition of the socio-cultural impacts of marine plastic pollution and a conceptual framework for categorizing the impacts. It highlights three dimensions of the socio-cultural impacts of marine plastic pollution (lifestyle, mental health, and cultural and heritage impacts). It also illustrates connections between marine ecosystems and marine-based livelihood activities with the social and cultural dimensions of human wellbeing to show the links between marine environments and socio-cultural contexts. Concerning stakeholder perceptions, the study showed a tendency to associate marine plastic pollution with immediate, noticeable and easily quantifiable ecological impacts such as entanglement and ingestion of marine organisms, economic impacts and social impacts (e.g., loss of aesthetic appeal). However, secondary impacts such as loss of marine biodiversity and social impacts such as human health, were largely unknown. Moreover, there was heterogeneity in perceptions of marine plastic pollution impacts among the stakeholder groups. Prospective studies researching marine plastic pollution impacts should consider divergent and diverse perceptions of different stakeholders to capture the real costs of marine plastic pollution. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Yose, Papama
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424743 , vital:72180
- Description: Marine plastic pollution is one of the major environmental problems globally, with adverse impacts on marine ecosystem services, functions and benefits and people. Yet, compared to plastic pollution impacts on terrestrial ecosystems, the impacts of plastic waste on marine ecosystems are little studied and poorly understood in South Africa. In response, research interest on the ecological and economic impacts of marine plastic pollution has grown rapidly but socio-cultural impacts remain poorly conceptualized and little understudied. This trend is arguably driven by the dominance of a quantitative paradigm which is arguably inadequate to respond to dynamic socio-cultural issues and contexts. Further, in South Africa, marine ecosystems are used by diverse groups of people ranging from subsistence users, tourism operators, commercial fishers and recreational users, meaning that addressing marine plastic pollution requires a multi-stakeholder approach. However, few studies explore the perceptions of diverse stakeholders regarding marine plastic pollution, its impacts and potential interventions. Against this background, the objective of the thesis are twofold: (a) to argue for a more nuanced understanding of marine plastic pollution impacts on human well-being in order to strengthen conceptualization of impacts that goes beyond direct and quantitatively measured impacts (ecological, health and economic) but considers the socio-cultural dimensions of impacts (lifestyle disruptions, mental health costs and cultural and heritage impacts), and (b) examine stakeholders’ perceptions of marine plastic pollution, its impacts and potential interventions in South Africa. Drawing on case studies, this study provides a working definition of the socio-cultural impacts of marine plastic pollution and a conceptual framework for categorizing the impacts. It highlights three dimensions of the socio-cultural impacts of marine plastic pollution (lifestyle, mental health, and cultural and heritage impacts). It also illustrates connections between marine ecosystems and marine-based livelihood activities with the social and cultural dimensions of human wellbeing to show the links between marine environments and socio-cultural contexts. Concerning stakeholder perceptions, the study showed a tendency to associate marine plastic pollution with immediate, noticeable and easily quantifiable ecological impacts such as entanglement and ingestion of marine organisms, economic impacts and social impacts (e.g., loss of aesthetic appeal). However, secondary impacts such as loss of marine biodiversity and social impacts such as human health, were largely unknown. Moreover, there was heterogeneity in perceptions of marine plastic pollution impacts among the stakeholder groups. Prospective studies researching marine plastic pollution impacts should consider divergent and diverse perceptions of different stakeholders to capture the real costs of marine plastic pollution. , Thesis (MSc) -- Faculty of Science, Environmental Science, 2023
- Full Text:
- 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
- Full Text:
- Date Issued: 2023-10-13
- 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
- Full Text:
- Date Issued: 2023-10-13
M3: Mining Mini-Halos with MeerKAT
- Authors: Trehaeven, Keegan Somerset
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424754 , vital:72181
- Description: This work aims to showcase the MeerKAT telescope’s capabilities and related calibration and imaging software in studying the emission of radio mini-halos. These diffuse radio synchrotron sources surround a Brightest Cluster Galaxy (BCG) in relatively relaxed clusters out to a few 100 kpc in size. They are difficult to image because of their relatively low surface brightness and small angular size. Hence, they could not be studied in great detail by previous generations of radio telescopes and much about their nature, particularly the exact production mechanism, is not yet fully understood. Thus, for the first time, MeerKAT observed a sample of five galaxy clusters to investigate the central radio mini-halo in each. Studying these sources requires the deepest images generated from the data and the effective subtraction of any projected sources obscuring or contaminating the underlying diffuse emission. Therefore, I describe the data reduction used to create third-generation calibrated, primary beam corrected, point source subtracted Stokes I L-band continuum images of these clusters. For first- and second-generation calibration, I use the CARACal pipeline, which implements software optimised explicitly for MeerKAT data. For third-generation calibration, I use the faceted approach of killMS and DDFacet, and then I perform visibility-plane point source subtraction to disentangle the compact and diffuse emissions. I then measured the size, flux density, in-band spectral properties, and radio power of the central mini-halos. I present the first new mini-halo detection by MeerKAT (MACS J2140.2-2339, Trehaeven et al. accepted), the first spectral index maps of these mini-halos, which show very interesting distributions, and a ∼100 kpc II southern extension to the ACO 3444 mini-halo previously unseen in archival VLA data. Thereafter, I present a multi-wavelength case study for two complementary mini-halos from our sample and show via a radio-to-X-ray spatial correlation test that they might be caused by different particle (re)-acceleration mechanisms. Through these initial science results, I have shown that future observations of radio mini-halos with MeerKAT are an exciting prospect that can lead to a better understanding of the fundamental physics behind these sources. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Trehaeven, Keegan Somerset
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424754 , vital:72181
- Description: This work aims to showcase the MeerKAT telescope’s capabilities and related calibration and imaging software in studying the emission of radio mini-halos. These diffuse radio synchrotron sources surround a Brightest Cluster Galaxy (BCG) in relatively relaxed clusters out to a few 100 kpc in size. They are difficult to image because of their relatively low surface brightness and small angular size. Hence, they could not be studied in great detail by previous generations of radio telescopes and much about their nature, particularly the exact production mechanism, is not yet fully understood. Thus, for the first time, MeerKAT observed a sample of five galaxy clusters to investigate the central radio mini-halo in each. Studying these sources requires the deepest images generated from the data and the effective subtraction of any projected sources obscuring or contaminating the underlying diffuse emission. Therefore, I describe the data reduction used to create third-generation calibrated, primary beam corrected, point source subtracted Stokes I L-band continuum images of these clusters. For first- and second-generation calibration, I use the CARACal pipeline, which implements software optimised explicitly for MeerKAT data. For third-generation calibration, I use the faceted approach of killMS and DDFacet, and then I perform visibility-plane point source subtraction to disentangle the compact and diffuse emissions. I then measured the size, flux density, in-band spectral properties, and radio power of the central mini-halos. I present the first new mini-halo detection by MeerKAT (MACS J2140.2-2339, Trehaeven et al. accepted), the first spectral index maps of these mini-halos, which show very interesting distributions, and a ∼100 kpc II southern extension to the ACO 3444 mini-halo previously unseen in archival VLA data. Thereafter, I present a multi-wavelength case study for two complementary mini-halos from our sample and show via a radio-to-X-ray spatial correlation test that they might be caused by different particle (re)-acceleration mechanisms. Through these initial science results, I have shown that future observations of radio mini-halos with MeerKAT are an exciting prospect that can lead to a better understanding of the fundamental physics behind these sources. , Thesis (MSc) -- Faculty of Science, Physics and Electronics, 2023
- Full Text:
- Date Issued: 2023-10-13
The effects of short-duration overnight kraaling on herbaceous vegetation and soils in mesic grassland
- Authors: Mgwali, Nompendulo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424721 , vital:72178
- Description: Land degradation is widespread in communal rangelands in the grassland biome of South Africa, and often attributed to overstocking and lack of coordinated management. Excessive pressure on the herbaceous component has contributed to the uncontrolled spread of opportunistic invasive alien woody species e.g. Acacia mearnsii in many degraded areas, resulting in significant loss of ecosystem service capacity, along with soil and land productivity. Short-duration overnight kraaling has been suggested as a tool for restoring degraded rangelands. Recent studies in semi-arid savannas and shrublands have reported increased grass cover, soil nutrients and palatability and concluded that short-duration kraaling is a low-cost and effective way of restoring degraded rangelands using livestock. However, the response of different plant functional types and communities to such intense livestock impact may vary depending on local context. This study used twelve paired kraal and control sites to investigate the effects of short-duration (7-24 days) overnight kraaling of livestock on herbaceous vegetation and soils in a mesic grassland. The study area is generally considered to be overgrazed but has considerable variation in grass composition and basal cover. Sites included relatively intact natural grassland and sites where wattle infestations had been cleared and where mostly bare ground remained. I tested the hypotheses that overnight kraaling would result in (1) increased basal cover due to introduction of grass seed and stimulation of germination through hoof action, (2) increased infiltration due to hoof action, and (3) increased soil nutrients and organic matter due to dung and urine deposition. I also hypothesized that factors such as a site’s initial grass cover, its slope, the occurrence and amount of rainfall before and during kraaling, and the kraaling intensity (number of livestock and duration of the kraaling event) would influence the magnitude and direction of the kraaling effect. The effect of kraaling on vegetation was strongly dependent on initial condition. Kraaling increased basal cover of grasses when sites had low initial basal cover, but decreased basal cover if initial values were over 50%. Infiltration increased if kraaling took place during or after rain but decreased if kraaling took place when soils were dry. Kraaling increased soil P and K. In mesic grasslands, short-duration overnight kraaling is promising as a tool for rehabilitating degraded sites but should be avoided where the grass sward is relatively intact. I recommend that the suitability of kraaling be further evaluated per vegetation type and local context. , Thesis (MSc) -- Faculty of Science, Botany, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Mgwali, Nompendulo
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424721 , vital:72178
- Description: Land degradation is widespread in communal rangelands in the grassland biome of South Africa, and often attributed to overstocking and lack of coordinated management. Excessive pressure on the herbaceous component has contributed to the uncontrolled spread of opportunistic invasive alien woody species e.g. Acacia mearnsii in many degraded areas, resulting in significant loss of ecosystem service capacity, along with soil and land productivity. Short-duration overnight kraaling has been suggested as a tool for restoring degraded rangelands. Recent studies in semi-arid savannas and shrublands have reported increased grass cover, soil nutrients and palatability and concluded that short-duration kraaling is a low-cost and effective way of restoring degraded rangelands using livestock. However, the response of different plant functional types and communities to such intense livestock impact may vary depending on local context. This study used twelve paired kraal and control sites to investigate the effects of short-duration (7-24 days) overnight kraaling of livestock on herbaceous vegetation and soils in a mesic grassland. The study area is generally considered to be overgrazed but has considerable variation in grass composition and basal cover. Sites included relatively intact natural grassland and sites where wattle infestations had been cleared and where mostly bare ground remained. I tested the hypotheses that overnight kraaling would result in (1) increased basal cover due to introduction of grass seed and stimulation of germination through hoof action, (2) increased infiltration due to hoof action, and (3) increased soil nutrients and organic matter due to dung and urine deposition. I also hypothesized that factors such as a site’s initial grass cover, its slope, the occurrence and amount of rainfall before and during kraaling, and the kraaling intensity (number of livestock and duration of the kraaling event) would influence the magnitude and direction of the kraaling effect. The effect of kraaling on vegetation was strongly dependent on initial condition. Kraaling increased basal cover of grasses when sites had low initial basal cover, but decreased basal cover if initial values were over 50%. Infiltration increased if kraaling took place during or after rain but decreased if kraaling took place when soils were dry. Kraaling increased soil P and K. In mesic grasslands, short-duration overnight kraaling is promising as a tool for rehabilitating degraded sites but should be avoided where the grass sward is relatively intact. I recommend that the suitability of kraaling be further evaluated per vegetation type and local context. , Thesis (MSc) -- Faculty of Science, Botany, 2023
- Full Text:
- Date Issued: 2023-10-13
The yield spread as a predictor for buy or sell signals for sectoral indices of the JSE
- Authors: Roeber, Christine
- Date: 2023-10-13
- Subjects: Yield curve , Rate of return South Africa , Yield spread , Interest rate , Johannesburg Stock Exchange
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419687 , vital:71666
- Description: The predictive nature of the yield curve has been of interest to researchers for years. In this thesis, the evidence for the yield curve as a predictor is examine, specifically as a predictor for bear markets in the JSE stock market for 8 sub-sectoral indices. The study explores a dynamic market timing strategy for timing the South African stock market compared to a normal buy-and-hold strategy. First, probit models are estimated for each of the sectoral indices which did not prove to have tracked well all the bear market phases. Then a dynamic market timing portfolio is simulated against a buy-and-hold only strategy, the dynamic market timing portfolio proved to have outperformed a buy-and-hold strategy for almost all the indices. Thus, a Henriksson-Merton parametric model test which tests for market timing ability was done on these sub-indices. The research finds that the yield curve in South Africa is not a useful tool for a buy-sell strategy for most of the sub-sectoral indices of the JSE. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Roeber, Christine
- Date: 2023-10-13
- Subjects: Yield curve , Rate of return South Africa , Yield spread , Interest rate , Johannesburg Stock Exchange
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419687 , vital:71666
- Description: The predictive nature of the yield curve has been of interest to researchers for years. In this thesis, the evidence for the yield curve as a predictor is examine, specifically as a predictor for bear markets in the JSE stock market for 8 sub-sectoral indices. The study explores a dynamic market timing strategy for timing the South African stock market compared to a normal buy-and-hold strategy. First, probit models are estimated for each of the sectoral indices which did not prove to have tracked well all the bear market phases. Then a dynamic market timing portfolio is simulated against a buy-and-hold only strategy, the dynamic market timing portfolio proved to have outperformed a buy-and-hold strategy for almost all the indices. Thus, a Henriksson-Merton parametric model test which tests for market timing ability was done on these sub-indices. The research finds that the yield curve in South Africa is not a useful tool for a buy-sell strategy for most of the sub-sectoral indices of the JSE. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13
The role of local level agency in a just green transition: the case of Rhodes University
- Authors: Nel, Vanray
- Date: 2023-10-13
- Subjects: Green economy , Just Transition , Clean energy South Africa Makhanda , Rhodes University , Triple bottom line , Sustainable development South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419643 , vital:71662
- Description: The research uses a richly contextualised case study of Rhodes University to explore the role of local level agency in a just green transition. The central concept of the thesis is mainstreaming sustainability. Sustainability has become a core objective both at the macro and micro levels. The just green transition and triple bottom line are shorthand for these macro and micro concepts. At the macro level, there is increasing evidence suggesting that transitioning to a sustainable economy can be a key driver of economic development. At the micro level, the elements of the triple bottom line increasingly overlap, with sustainability no longer a separate goal, or a ‘nice to have’, but integral to organisational success. However, this potential is clearly not being realised, and sustainability often remains ‘niche’. Lack of progress at the macro-level reinforces the importance of bottom-up, local level agency. In keeping with the broader micro-level literature, the case study strongly suggests that mainstreaming sustainability would have multiple benefits. These include reducing dependence on unreliable state-provided services and enhancing Rhodes University’s standing as a genuinely transformative institution. The evidence suggests that there is a pure financial case for green investments, such as the construction of a solar farm at Rhodes University, even before accounting for the social and environmental benefits of such an initiative. This shifts the focus to why institutions like Rhodes University have not been proactive in mainstreaming sustainability. The document analysis and the interviews showed that there is an awareness of the importance and potential of mainstreaming sustainability. However, the funding squeeze is often misperceived as a binding constraint, and there is an absence of innovative thinking about how to finance projects with high returns, such as a solar farm. A theme amongst several of the interviewees was that the university should embrace a policy of enhancing small changes as a way of mainstreaming sustainability gradually. Even here, there are doubts about whether the organisational structure of the university will allow this. On the other hand, there are positive signs that the increasing sense of crisis means management and other key stakeholders are gradually shifting towards seeing the crucial importance of the university embracing a more proactive stance. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Nel, Vanray
- Date: 2023-10-13
- Subjects: Green economy , Just Transition , Clean energy South Africa Makhanda , Rhodes University , Triple bottom line , Sustainable development South Africa Makhanda
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419643 , vital:71662
- Description: The research uses a richly contextualised case study of Rhodes University to explore the role of local level agency in a just green transition. The central concept of the thesis is mainstreaming sustainability. Sustainability has become a core objective both at the macro and micro levels. The just green transition and triple bottom line are shorthand for these macro and micro concepts. At the macro level, there is increasing evidence suggesting that transitioning to a sustainable economy can be a key driver of economic development. At the micro level, the elements of the triple bottom line increasingly overlap, with sustainability no longer a separate goal, or a ‘nice to have’, but integral to organisational success. However, this potential is clearly not being realised, and sustainability often remains ‘niche’. Lack of progress at the macro-level reinforces the importance of bottom-up, local level agency. In keeping with the broader micro-level literature, the case study strongly suggests that mainstreaming sustainability would have multiple benefits. These include reducing dependence on unreliable state-provided services and enhancing Rhodes University’s standing as a genuinely transformative institution. The evidence suggests that there is a pure financial case for green investments, such as the construction of a solar farm at Rhodes University, even before accounting for the social and environmental benefits of such an initiative. This shifts the focus to why institutions like Rhodes University have not been proactive in mainstreaming sustainability. The document analysis and the interviews showed that there is an awareness of the importance and potential of mainstreaming sustainability. However, the funding squeeze is often misperceived as a binding constraint, and there is an absence of innovative thinking about how to finance projects with high returns, such as a solar farm. A theme amongst several of the interviewees was that the university should embrace a policy of enhancing small changes as a way of mainstreaming sustainability gradually. Even here, there are doubts about whether the organisational structure of the university will allow this. On the other hand, there are positive signs that the increasing sense of crisis means management and other key stakeholders are gradually shifting towards seeing the crucial importance of the university embracing a more proactive stance. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13
Benchmarking tax practitioner regulation in Zimbabwe and South Africa against German best practice
- Authors: Munkuli, Charles
- Date: 2023-10-13
- Subjects: Tax consultants South Africa , Taxpayer compliance South Africa , Revenue authority , Taxation Law and legislation South Africa , Taxation Law and legislation Zimbabwe , Taxation Law and legislation Germany
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419621 , vital:71660
- Description: The regulation of professionals who offer any type of service to the public is a critical intervention towards protecting the public from unscrupulous behaviour. The regulation of tax practitioners is no exception as it is a critical element in protecting the taxpaying public and the fiscus against improper conduct by tax practitioners, as well as preventing revenue leakages due to inaccurate or incorrect declarations made by taxpayers. A major contributor of regulation would be strengthening or improving compliance. This study analyses the frameworks that regulate tax practitioners in Zimbabwe and South Africa and evaluates them against best practice as is found in Germany. Germany has been regulating tax practitioners for 50 years and can rightly be recognised as best practice. This is achieved by reviewing and evaluating institutional and legislative mechanisms in the regulatory frameworks adopted in the three countries in order to identify possible areas of improvement in Zimbabwe and South Africa. The research is situated in the interpretative paradigm and the research methodology is qualitative in nature, involving the critical review of documentary data. The study concludes that both South Africa and Zimbabwe have room to improve in certain areas and makes recommendations aimed at strengthening their respective regulatory frameworks. Both South Africa and Zimbabwe could promulgate a law that deals exclusively with the regulation of tax practitioners, and institute an independent body that deals exclusively with tax practitioner related issues. In Zimbabwe, the Public Accountants and Auditors’ Board should be replaced with a body dedicated to serving tax practitioners. Informing the taxpaying public is important and, particularly in Zimbabwe, measures should be adopted to inform taxpayers about their rights and obligations, the role of tax practitioners, and the interface with the tax administration. The Zimbabwean regulatory model should also recognise other non-accounting and auditing-oriented professions, such as the law profession, as tax practitioners. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Munkuli, Charles
- Date: 2023-10-13
- Subjects: Tax consultants South Africa , Taxpayer compliance South Africa , Revenue authority , Taxation Law and legislation South Africa , Taxation Law and legislation Zimbabwe , Taxation Law and legislation Germany
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419621 , vital:71660
- Description: The regulation of professionals who offer any type of service to the public is a critical intervention towards protecting the public from unscrupulous behaviour. The regulation of tax practitioners is no exception as it is a critical element in protecting the taxpaying public and the fiscus against improper conduct by tax practitioners, as well as preventing revenue leakages due to inaccurate or incorrect declarations made by taxpayers. A major contributor of regulation would be strengthening or improving compliance. This study analyses the frameworks that regulate tax practitioners in Zimbabwe and South Africa and evaluates them against best practice as is found in Germany. Germany has been regulating tax practitioners for 50 years and can rightly be recognised as best practice. This is achieved by reviewing and evaluating institutional and legislative mechanisms in the regulatory frameworks adopted in the three countries in order to identify possible areas of improvement in Zimbabwe and South Africa. The research is situated in the interpretative paradigm and the research methodology is qualitative in nature, involving the critical review of documentary data. The study concludes that both South Africa and Zimbabwe have room to improve in certain areas and makes recommendations aimed at strengthening their respective regulatory frameworks. Both South Africa and Zimbabwe could promulgate a law that deals exclusively with the regulation of tax practitioners, and institute an independent body that deals exclusively with tax practitioner related issues. In Zimbabwe, the Public Accountants and Auditors’ Board should be replaced with a body dedicated to serving tax practitioners. Informing the taxpaying public is important and, particularly in Zimbabwe, measures should be adopted to inform taxpayers about their rights and obligations, the role of tax practitioners, and the interface with the tax administration. The Zimbabwean regulatory model should also recognise other non-accounting and auditing-oriented professions, such as the law profession, as tax practitioners. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
The complexities of transfer pricing methods and the role of advance pricing agreements and tax audits in addressing disputes
- Authors: Ndou, Wavhudi
- Date: 2023-10-13
- Subjects: Transfer pricing Taxation Law and legislation South Africa , Advance pricing agreement , Double taxation , Arms-length transactions , Tax auditing , Advance tax ruling , Organisation for Economic Co-operation and Development , United Nations , World Bank
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419631 , vital:71661
- Description: Base erosion and profit shifting is defined as the use of tax planning strategies by multinational enterprises, often through exploiting gaps and mismatches between the countries in which they operate (OECD, 2021: p. 1). Multinational enterprises exploit these gaps through the use of transfer pricing. Goods and services are exchanged between connected persons or associated enterprises at prices that do not reflect their arm’s length price, in order to shift profits from high tax to low tax jurisdictions. In terms of section 31 of the Income Tax Act, transactions between connected persons or associated enterprises must be reflected at their arm’s length price. Transfer pricing has become an issue due to the difficulties in determining an appropriate arm’s length price. Disputes arise between a taxpayer and a tax administration on the methods to use to determine an appropriate transfer price. The use of Advance Pricing Agreements prevents these disputes from arising and provides tax certainty on the treatment of transactions for both the taxpayer and the tax administration. While the OECD recommends the use of Advance Pricing Agreements as a method to prevent disputes from arising, the OECD also argued that if a country has the resources to conduct an audit, an Advance Pricing Agreement will not lead to increased revenue collection. The research therefore analyses the problems faced in determining an appropriate arm's length price and compares the role that Advance Pricing Agreements and audits play in addressing transfer pricing issues. The possible role of Advance Tax Rulings is also explored, but they are found not to be suitable, except for the most simple transactions. The research applies a legal interpretative, doctrinal research methodology and a qualitative research method. The data comprised of relevant South African tax legislation, OECD Guidelines, the World Bank Handbook, and the UN Manual, together with the writings of acknowledged experts in the field. The study establishes that a proper functioning audit system is crucial to increasing revenue collection once a country implements an Advance Pricing Agreement. The research therefore recommends the adoption of Advance Pricing Agreements in South Africa as a dispute prevention measure. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Ndou, Wavhudi
- Date: 2023-10-13
- Subjects: Transfer pricing Taxation Law and legislation South Africa , Advance pricing agreement , Double taxation , Arms-length transactions , Tax auditing , Advance tax ruling , Organisation for Economic Co-operation and Development , United Nations , World Bank
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419631 , vital:71661
- Description: Base erosion and profit shifting is defined as the use of tax planning strategies by multinational enterprises, often through exploiting gaps and mismatches between the countries in which they operate (OECD, 2021: p. 1). Multinational enterprises exploit these gaps through the use of transfer pricing. Goods and services are exchanged between connected persons or associated enterprises at prices that do not reflect their arm’s length price, in order to shift profits from high tax to low tax jurisdictions. In terms of section 31 of the Income Tax Act, transactions between connected persons or associated enterprises must be reflected at their arm’s length price. Transfer pricing has become an issue due to the difficulties in determining an appropriate arm’s length price. Disputes arise between a taxpayer and a tax administration on the methods to use to determine an appropriate transfer price. The use of Advance Pricing Agreements prevents these disputes from arising and provides tax certainty on the treatment of transactions for both the taxpayer and the tax administration. While the OECD recommends the use of Advance Pricing Agreements as a method to prevent disputes from arising, the OECD also argued that if a country has the resources to conduct an audit, an Advance Pricing Agreement will not lead to increased revenue collection. The research therefore analyses the problems faced in determining an appropriate arm's length price and compares the role that Advance Pricing Agreements and audits play in addressing transfer pricing issues. The possible role of Advance Tax Rulings is also explored, but they are found not to be suitable, except for the most simple transactions. The research applies a legal interpretative, doctrinal research methodology and a qualitative research method. The data comprised of relevant South African tax legislation, OECD Guidelines, the World Bank Handbook, and the UN Manual, together with the writings of acknowledged experts in the field. The study establishes that a proper functioning audit system is crucial to increasing revenue collection once a country implements an Advance Pricing Agreement. The research therefore recommends the adoption of Advance Pricing Agreements in South Africa as a dispute prevention measure. , Thesis (MCom) -- Faculty of Commerce, Accounting, 2023
- Full Text:
- Date Issued: 2023-10-13
Quinolone-Pyrazinamide Derivatives: synthesis, characterisation, in silico ADME analysis and in vitro biological evaluation against Mycobacterium tuberculosis
- Authors: Rukweza, Kudakwashe Gerald
- Date: 2023-10-13
- Subjects: Quinolone antibacterial agents , Mycobacterium tuberculosis , Antitubercular agents , Tuberculosis Chemotherapy , Drug resistance , Moxifloxacin , Isoniazid
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/390901 , vital:68596
- Description: Tuberculosis is one of the leading causes of death worldwide caused by an infectious species, Mycobacterium tuberculosis (Mtb). Some of the factors that contribute to the prevalence of this disease include the complexity of diagnosis, prolonged period of therapy, side effects associated with current TB drugs, the prevalence of resistance against the current treatment options and a high incidence of co-infection with HIV/AIDS. Thus, there is a need for new alternative drugs to provide safer and shorter treatment therapy options that are not susceptible to the development of drug resistance. In this project, we focus our attention on the quinolone pharmacophore. Quinolones are currently used as alternative options in the treatment of resistant strains of Mtb. Previous work pertaining to quinolone-isoniazid hybrid compounds showed promising in vitro activity against the H37Rv strain of Mtb and served as the inspiration to pursue this project. The journey commenced with the synthesis of quinolone-pyrazinamide hybrid compounds (Figure 3.1). These compounds were synthesised, through the attachment of the quinolone and the pyrazinamide entity through a hydrazine linker. The synthesised compounds were purified, and their structural identity confirmed using common spectroscopic techniques including 1H and 13C NMR, infra-red (IR) and mass spectrometry. In vitro biological assays were performed by testing for the activity against the H37RvMA strain of Mtb. The bioassays were performed in triplicates to ensure the accuracy of the results. Moxifloxacin and isoniazid were tested as control compounds. Finally, the resultant compounds were profiled in silico for physicochemical and ADMET properties using open access software SwissADME. All the synthesised compounds 3.8a-f showed no activity against H37RvMA. In most cases, the resulting compounds showed minimal to no activity (MICs ≥ 57.3 μM) in all three media. During the in vitro studies, the compounds showed significant precipitation in the media over time suggesting poor aqueous solubility. The SwissADME analysis of these compounds indicated poor solubility in aqueous media, which is likely linked to their molecular size and complexity. Despite poor aqueous solubility, compounds 3.8a-f showed acceptable physicochemical properties and ADME parameters. No PAINs (Pan-assay interference compounds) were observed. Minimal to no interaction with CYP enzymes were predicted. Most of the compounds were compatible with the Lipinski’s rules of five. , Thesis (MSc) -- Faculty of Science, Pharmacy, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Rukweza, Kudakwashe Gerald
- Date: 2023-10-13
- Subjects: Quinolone antibacterial agents , Mycobacterium tuberculosis , Antitubercular agents , Tuberculosis Chemotherapy , Drug resistance , Moxifloxacin , Isoniazid
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/390901 , vital:68596
- Description: Tuberculosis is one of the leading causes of death worldwide caused by an infectious species, Mycobacterium tuberculosis (Mtb). Some of the factors that contribute to the prevalence of this disease include the complexity of diagnosis, prolonged period of therapy, side effects associated with current TB drugs, the prevalence of resistance against the current treatment options and a high incidence of co-infection with HIV/AIDS. Thus, there is a need for new alternative drugs to provide safer and shorter treatment therapy options that are not susceptible to the development of drug resistance. In this project, we focus our attention on the quinolone pharmacophore. Quinolones are currently used as alternative options in the treatment of resistant strains of Mtb. Previous work pertaining to quinolone-isoniazid hybrid compounds showed promising in vitro activity against the H37Rv strain of Mtb and served as the inspiration to pursue this project. The journey commenced with the synthesis of quinolone-pyrazinamide hybrid compounds (Figure 3.1). These compounds were synthesised, through the attachment of the quinolone and the pyrazinamide entity through a hydrazine linker. The synthesised compounds were purified, and their structural identity confirmed using common spectroscopic techniques including 1H and 13C NMR, infra-red (IR) and mass spectrometry. In vitro biological assays were performed by testing for the activity against the H37RvMA strain of Mtb. The bioassays were performed in triplicates to ensure the accuracy of the results. Moxifloxacin and isoniazid were tested as control compounds. Finally, the resultant compounds were profiled in silico for physicochemical and ADMET properties using open access software SwissADME. All the synthesised compounds 3.8a-f showed no activity against H37RvMA. In most cases, the resulting compounds showed minimal to no activity (MICs ≥ 57.3 μM) in all three media. During the in vitro studies, the compounds showed significant precipitation in the media over time suggesting poor aqueous solubility. The SwissADME analysis of these compounds indicated poor solubility in aqueous media, which is likely linked to their molecular size and complexity. Despite poor aqueous solubility, compounds 3.8a-f showed acceptable physicochemical properties and ADME parameters. No PAINs (Pan-assay interference compounds) were observed. Minimal to no interaction with CYP enzymes were predicted. Most of the compounds were compatible with the Lipinski’s rules of five. , Thesis (MSc) -- Faculty of Science, Pharmacy, 2023
- Full Text:
- Date Issued: 2023-10-13
Liquidity shocks and capital market efficiency in South Africa
- Matapuri, Dexter Tinotenda Kushinga
- Authors: Matapuri, Dexter Tinotenda Kushinga
- Date: 2023-10-13
- Subjects: Liquidity (Economics) , Stock exchanges South Africa , Insolvency , Securities South Africa , Capital market South Africa , Investments, Foreign
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419610 , vital:71659
- Description: Financial markets are dynamic in nature. As such, one way to keep up with their plethora of variables is to conduct research and seek understanding on how they all work together. Understanding financial market mechanics is the key to achieving and maintaining efficient capital markets. The goal of many economies is to have efficient capital markets mainly because they entail economic growth. One of the common avenues here being foreign direct investments. Therefore, over the years, a lot of financial economics research has been conducted on how best to attain financial market development which ultimately yields capital market efficiency. The opposite is also true. This research therefore set out to study the impact of liquidity shocks on capital market efficiency, more specifically stock market efficiency. As such, the overarching research goal was to determine the link between liquidity shocks and stock market efficiency in South Africa. Furthermore, the research also tested whether there is a homogenous impact exerted by liquidity shocks on the JSE Financial 15, JSE Industrial 25 and JSE Resource 20 indices. The arguments and thus conclusions of the research were constructed based on existing theories such as the Efficient Market hypothesis, Behavioural Finance and the Adaptive Market Hypothesis. Literature and existing empirical evidence related to the topic were also analysed and used for the same purpose. Econometric methods used to achieve these research goals include the time series and panel ARDL, impulse response and variance decomposition tests and the Granger Causality tests. The research found that liquidity shocks do impact stock market efficiency in South Africa in both the short run and long run. The direction of the impact was noted to vary with time and dependent on the liquidity shock proxy. Key findings here were that liquidity shocks lower JSE All-Share index efficiency in the short run thus allowing market participants to beat the market in the initial phases of a liquidity shock. Adding on, it was also found that illiquidity shocks lower efficiency for the JSE Financial 15 and Industrial 25 indices in the short run. In the long run, stock market efficiency is enhanced no matter the source of the shock. As such, the research recommended that regulatory policies should focus on liquidity shocks in the short run for the JSE All-Share index and on illiquidity shocks in the short run for the Financial 15 and Industrial 25 indices. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13
- Authors: Matapuri, Dexter Tinotenda Kushinga
- Date: 2023-10-13
- Subjects: Liquidity (Economics) , Stock exchanges South Africa , Insolvency , Securities South Africa , Capital market South Africa , Investments, Foreign
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/419610 , vital:71659
- Description: Financial markets are dynamic in nature. As such, one way to keep up with their plethora of variables is to conduct research and seek understanding on how they all work together. Understanding financial market mechanics is the key to achieving and maintaining efficient capital markets. The goal of many economies is to have efficient capital markets mainly because they entail economic growth. One of the common avenues here being foreign direct investments. Therefore, over the years, a lot of financial economics research has been conducted on how best to attain financial market development which ultimately yields capital market efficiency. The opposite is also true. This research therefore set out to study the impact of liquidity shocks on capital market efficiency, more specifically stock market efficiency. As such, the overarching research goal was to determine the link between liquidity shocks and stock market efficiency in South Africa. Furthermore, the research also tested whether there is a homogenous impact exerted by liquidity shocks on the JSE Financial 15, JSE Industrial 25 and JSE Resource 20 indices. The arguments and thus conclusions of the research were constructed based on existing theories such as the Efficient Market hypothesis, Behavioural Finance and the Adaptive Market Hypothesis. Literature and existing empirical evidence related to the topic were also analysed and used for the same purpose. Econometric methods used to achieve these research goals include the time series and panel ARDL, impulse response and variance decomposition tests and the Granger Causality tests. The research found that liquidity shocks do impact stock market efficiency in South Africa in both the short run and long run. The direction of the impact was noted to vary with time and dependent on the liquidity shock proxy. Key findings here were that liquidity shocks lower JSE All-Share index efficiency in the short run thus allowing market participants to beat the market in the initial phases of a liquidity shock. Adding on, it was also found that illiquidity shocks lower efficiency for the JSE Financial 15 and Industrial 25 indices in the short run. In the long run, stock market efficiency is enhanced no matter the source of the shock. As such, the research recommended that regulatory policies should focus on liquidity shocks in the short run for the JSE All-Share index and on illiquidity shocks in the short run for the Financial 15 and Industrial 25 indices. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2023
- Full Text:
- Date Issued: 2023-10-13