Classification and clustering based methods for outlier detection of solar resource data
- Authors: Abrahams, Waldo
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55423 , vital:51996
- Description: Almost 90% of the primary global energy demand is serviced from the burning of fossil fuels (Abas, Kalair & Khan, 2015). Owing to the detrimental environmental impact of this, a global energy transition to the use of renewable energy, including solar energy, is needed (Gielen et al., 2019). An important aspect that inhibits the growth of solar energy is accurate solar resource data. Such data is needed because knowledge of the future reliability and quality of energy production is required to analyse a system’s performance and determine financial implications (Sengupta et al., 2017). Existing methods used to detect outliers in solar resource data do not efficiently identify outliers and an accurate and robust approach is required (Eastwood, 2019). Using simulated and real-world data, this study investigates the use of several classification methods, along with a two-stage clustering-classification approach to accurately identify outliers in solar resource data. The Treebag method proves to be an adequate outlier detection method for solar resource data. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Abrahams, Waldo
- Date: 2022-04
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55423 , vital:51996
- Description: Almost 90% of the primary global energy demand is serviced from the burning of fossil fuels (Abas, Kalair & Khan, 2015). Owing to the detrimental environmental impact of this, a global energy transition to the use of renewable energy, including solar energy, is needed (Gielen et al., 2019). An important aspect that inhibits the growth of solar energy is accurate solar resource data. Such data is needed because knowledge of the future reliability and quality of energy production is required to analyse a system’s performance and determine financial implications (Sengupta et al., 2017). Existing methods used to detect outliers in solar resource data do not efficiently identify outliers and an accurate and robust approach is required (Eastwood, 2019). Using simulated and real-world data, this study investigates the use of several classification methods, along with a two-stage clustering-classification approach to accurately identify outliers in solar resource data. The Treebag method proves to be an adequate outlier detection method for solar resource data. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2022
- Full Text:
- Date Issued: 2022-04
The role of climate change on food security in Northern Uganda a case study of Lira district
- Authors: Aciro, Prudence Estel
- Date: 2022-04
- Subjects: Food security -- Uganda , Food security -- Climatic factors , Climatic changes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57513 , vital:58054
- Description: The study examines the effects of climate change in Northern Uganda to create food security solutions through the improvement of local resilience mechanisms and adaptation devices. The study adopted the interpretive paradigm within the qualitative research methodology as it investigated the subjective opinions of the respondents about the role of climate change on food security in the Lira district. The researcher used non-probability purposive sampling to identify nine officials that possessed knowledge on resilience mechanisms and also interacted directly with individual farmers. The researcher used semi-structured interviews as a tool to collect data and thematic analysis to make conclusions on findings based on the emerging themes. The findings from the study revealed that the four determinants of food security are greatly affected by climate events and these are: food utilisation, food production, food availability and access to food as well as the stability of food supply. Food storage is a problem facing the community of Lira due to extreme climate events. Climate change was found to affect food prices in such a way that when agricultural inputs are bought expensively, it leads the cost of producing crops to increase, which in turn makes food more expensive at the market. The findings also displayed that Lira’s local communities are trying to apply adaptive farming practices to ensure there is an adequate food supply, such as planting a local variety of seeds that withstand the effect of climate change, such as sorghum millet and cassava. Based on the findings, valuable recommendations are offered. These include the government rolling out a national irrigation scheme to ease the use of the drip irrigation mechanism. Also, there is a need for more interventions that support local resilience mechanisms such as the use of agricultural inputs, as these require subsidisation. It emerged from the findings of this study that there is a need for better interventions to deal with flooding. For future researchers, it was found that there is a need to explore the best post-harvest handling methods as well as food storage. , Thesis (MA) -- Faculty of Business and Economic Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Aciro, Prudence Estel
- Date: 2022-04
- Subjects: Food security -- Uganda , Food security -- Climatic factors , Climatic changes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57513 , vital:58054
- Description: The study examines the effects of climate change in Northern Uganda to create food security solutions through the improvement of local resilience mechanisms and adaptation devices. The study adopted the interpretive paradigm within the qualitative research methodology as it investigated the subjective opinions of the respondents about the role of climate change on food security in the Lira district. The researcher used non-probability purposive sampling to identify nine officials that possessed knowledge on resilience mechanisms and also interacted directly with individual farmers. The researcher used semi-structured interviews as a tool to collect data and thematic analysis to make conclusions on findings based on the emerging themes. The findings from the study revealed that the four determinants of food security are greatly affected by climate events and these are: food utilisation, food production, food availability and access to food as well as the stability of food supply. Food storage is a problem facing the community of Lira due to extreme climate events. Climate change was found to affect food prices in such a way that when agricultural inputs are bought expensively, it leads the cost of producing crops to increase, which in turn makes food more expensive at the market. The findings also displayed that Lira’s local communities are trying to apply adaptive farming practices to ensure there is an adequate food supply, such as planting a local variety of seeds that withstand the effect of climate change, such as sorghum millet and cassava. Based on the findings, valuable recommendations are offered. These include the government rolling out a national irrigation scheme to ease the use of the drip irrigation mechanism. Also, there is a need for more interventions that support local resilience mechanisms such as the use of agricultural inputs, as these require subsidisation. It emerged from the findings of this study that there is a need for better interventions to deal with flooding. For future researchers, it was found that there is a need to explore the best post-harvest handling methods as well as food storage. , Thesis (MA) -- Faculty of Business and Economic Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Evaluation of groundwater potential using geological and geophysical methods in the University of Fort Hare Alice Campus, Eastern Cape Province of South Africa
- Adesola, Gbenga Olamide https://orcid.org/0000-0002-4151-5305
- Authors: Adesola, Gbenga Olamide https://orcid.org/0000-0002-4151-5305
- Date: 2022-04
- Subjects: Groundwater , Geology, Structural -- South Africa , Geographical Information Systems
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22490 , vital:52344
- Description: Geological and geophysical methods were used to evaluate the groundwater potential in University of Fort Hare (Alice campus), Eastern Cape Province of South Africa. Methodologies adopted for obtaining these results included a comprehensive literature review, thin section analysis, scanning electron microscopy, Geographical Information Systems (GIS), remote sensing and geophysical investigations (magnetic survey and vertical electrical sounding). The geology of the study area belongs to the Balfour Formation, which forms part of the Beaufort Group in the Karoo Supergroup. The rocks within the study area are composed majorly of sandstone and mudstone. Lineaments were automatically extracted using the PCI Geomatica 2018 software. Fifteen samples were collected at various locations within the study area and were analyzed using the petrographic microscope while others were analyzed with the Scanning Electron Microscopic (SEM) combined with an Energy dispersive x-ray spectrometry. The results show that the rocks are fractured, porous and contained minerals such as quartz, feldspar, calcite, mica and clay minerals. The occurrence of these fractures helps to improve the groundwater storage capacity in the study area. Out of the twenty seven (27) rock samples collected in the field, ten (10) rock samples were selected for densities (dry, wet and grain densities) and porosity measurements in the laboratory. The rocks density values range from 2.5763 – 2.6978 g/cm3. The average porosities of the rocks range from 0.85 – 2.56 percent. The density of the sandstone ranges from 2.5908 – 2.6820 g/cm3 whilst the porosity range from 0.85 – 2.02 percent. The density of the mudstone ranges from 2.5763 – 2.6978 g/cm3 whilst the porosity ranges from 1.84 – 2.56 percent. About 8458 magnetic measurements were taken at about 20 m spacing along linear and non-linear paths and road. A variety of magnetic maps were generated. Several magnetic highs were observed and the linear highs were interpreted to be due to dolerite dykes whilst the broader high zones were inferred to be due to dolerite sills. These Karoo dolerites intruded the sediments at various depths and must have fractured the sediments causing them to be more porous and permeable. The depth slices of magnetic data reveal that near surface magnetic bodies occur within the depth of approximately 19 m from the surface while deep seated ones occur as deep as 31 m and maybe deeper. The knowledge of the dolerite intrusions enabled the location of drilling targets for groundwater. Electrical resistivity data were collected at 28 sites using the Schlumberger array and a maximum cable length (250 m) from the centre point which achieved a maximum depth penetration of about 70 m to 162 m. The results from 1D modelling using WINRESIST software showed that the vertical electric sounding curves are composed of HA and HK curve-types, which show four geoelectric layers. The resistivity of the first layer which is the topmost layer has values ranging from 20 - 5752 Ωm and the thickness is between 0.4 – 1.8 m. The second layer which consists of clay, mudstone and sandstone has resistivity values varying from 3 - 51 Ωm and thickness varying from 0.8 – 17.5 m. The third layer which is interpreted to be the aquiferous layer of the study area is made up majorly of sandstone with resistivity that varies from 136 – 352 Ωm and thickness range from 9.9 – 143.9 m. The fourth layer of resistivity varying from 44 to 60428 Ωm is made up of mudstone and sandstone, which are in some places intruded by dolerites. Groundwater potential is favourably high in some of the areas investigated. Furthermore, the results of the research indicated that secondary porosity is the main porosity for the reservoir rocks in the study area. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Adesola, Gbenga Olamide https://orcid.org/0000-0002-4151-5305
- Date: 2022-04
- Subjects: Groundwater , Geology, Structural -- South Africa , Geographical Information Systems
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/22490 , vital:52344
- Description: Geological and geophysical methods were used to evaluate the groundwater potential in University of Fort Hare (Alice campus), Eastern Cape Province of South Africa. Methodologies adopted for obtaining these results included a comprehensive literature review, thin section analysis, scanning electron microscopy, Geographical Information Systems (GIS), remote sensing and geophysical investigations (magnetic survey and vertical electrical sounding). The geology of the study area belongs to the Balfour Formation, which forms part of the Beaufort Group in the Karoo Supergroup. The rocks within the study area are composed majorly of sandstone and mudstone. Lineaments were automatically extracted using the PCI Geomatica 2018 software. Fifteen samples were collected at various locations within the study area and were analyzed using the petrographic microscope while others were analyzed with the Scanning Electron Microscopic (SEM) combined with an Energy dispersive x-ray spectrometry. The results show that the rocks are fractured, porous and contained minerals such as quartz, feldspar, calcite, mica and clay minerals. The occurrence of these fractures helps to improve the groundwater storage capacity in the study area. Out of the twenty seven (27) rock samples collected in the field, ten (10) rock samples were selected for densities (dry, wet and grain densities) and porosity measurements in the laboratory. The rocks density values range from 2.5763 – 2.6978 g/cm3. The average porosities of the rocks range from 0.85 – 2.56 percent. The density of the sandstone ranges from 2.5908 – 2.6820 g/cm3 whilst the porosity range from 0.85 – 2.02 percent. The density of the mudstone ranges from 2.5763 – 2.6978 g/cm3 whilst the porosity ranges from 1.84 – 2.56 percent. About 8458 magnetic measurements were taken at about 20 m spacing along linear and non-linear paths and road. A variety of magnetic maps were generated. Several magnetic highs were observed and the linear highs were interpreted to be due to dolerite dykes whilst the broader high zones were inferred to be due to dolerite sills. These Karoo dolerites intruded the sediments at various depths and must have fractured the sediments causing them to be more porous and permeable. The depth slices of magnetic data reveal that near surface magnetic bodies occur within the depth of approximately 19 m from the surface while deep seated ones occur as deep as 31 m and maybe deeper. The knowledge of the dolerite intrusions enabled the location of drilling targets for groundwater. Electrical resistivity data were collected at 28 sites using the Schlumberger array and a maximum cable length (250 m) from the centre point which achieved a maximum depth penetration of about 70 m to 162 m. The results from 1D modelling using WINRESIST software showed that the vertical electric sounding curves are composed of HA and HK curve-types, which show four geoelectric layers. The resistivity of the first layer which is the topmost layer has values ranging from 20 - 5752 Ωm and the thickness is between 0.4 – 1.8 m. The second layer which consists of clay, mudstone and sandstone has resistivity values varying from 3 - 51 Ωm and thickness varying from 0.8 – 17.5 m. The third layer which is interpreted to be the aquiferous layer of the study area is made up majorly of sandstone with resistivity that varies from 136 – 352 Ωm and thickness range from 9.9 – 143.9 m. The fourth layer of resistivity varying from 44 to 60428 Ωm is made up of mudstone and sandstone, which are in some places intruded by dolerites. Groundwater potential is favourably high in some of the areas investigated. Furthermore, the results of the research indicated that secondary porosity is the main porosity for the reservoir rocks in the study area. , Thesis (MSc) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
Effect of pomegranate (Punica granatum L) peel powder meal on growth performance, gut integrity, haemato-biochemical indices, meat, and bone quality of broiler chickens
- Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Authors: Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Date: 2022-04
- Subjects: Broilers (Chickens) , Meat -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23611 , vital:58218
- Description: The objective of the current study was to investigate the overall response of broiler birds to varying dietary levels of pomegranate (Punica granatum L) peel powder meal (PPPM). A total of 432-day-old Cobb 500 broiler chicks were randomly divided into six experimental groups of four replications with 18 birds per replicate in a completely randomized design (CRD). The birds were fed isonitrogenous and isocaloric experimental diets designated as: T1-control diet with 0percent additives (negative control; NEGCON); T2- control diet supplemented with α-tocopherol acetate at 200g per ton (positive control; POSCON): T3, T4, T5 and T6-control diet supplemented with 2, 4, 6 and 8g/kg PPPM (PPPM2, PPPM4, PPPM6, PPPM8). The phytochemical, nutritional and antioxidant properties of the pomegranate peel powder were determined. Results showed that the South African-grown pomegranate peel (“Wonderful” variety) had rich protein and trace mineral contents. Higher (p < 0.05) antioxidant and hepatic anti-lipid peroxidative activities were recorded in the ethanol and acetone extracts than the water extract, whereas the three extracts had no toxic effects on liver and kidney cells (p > 0.05). The dietary effects of PPPM supplementation on growth performance, digestibility, carcass, and organ weight indices of Cobb 500 birds were determined. The POSCON diet enhanced (p < 0.05) feed conversion ratio (FCR) at week 3. The average final body weight and average daily weight gain were highest (p < 0.05) in birds fed PPPM2 and PPPM4 diets, whereas birds fed PPPM2 diet had enhanced (p < 0.05) FCR and protein efficiency ratio when compared with birds on POSCON. Thigh and breast weights were highest (p < 0.05) in birds on PPPM4 and PPPM8 diets, whereas birds fed PPPM4 diet had enhanced (p < 0.05) nutrient digestibility compared with those on POSCON. The antioxidant status and breast meat quality of Cobb 500 broiler birds fed diets supplemented with PPPM were determined. Meat from birds fed PPPM8 diet had the highest (p < 0.05) thawing loss, while cooking loss was lowest (p < 0.05) in the PPPM2 group. The highest (p < 0.05) ability to scavenge ABTS [(2, 2-azinobis (3ethylbenzothiazoline-6 sulfonic acid))] radical cation (ABTS+) was recorded in the PPPM2 and PPPM4 meat while PPPM8 meat had increased (p < 0.05) catalase activity. The fatty acid composition, oxidative status, and drip loss in breast meat of Cobb 500 broiler birds fed graded levels of PPPM was determined. Meat from birds fed PPPM4 diet had the lowest (p < 0.05) margaric (C17:0) and arachidic (C20:0) acids, while meat from birds fed PPPM8 diet had higher (p < 0.05) levels of eicosadenoic (C20:2, n-6) and arachidonic (AA, 20:4) acids. The POSCON had higher (p < 0.05) ability to reduce TBARS levels in meat on day-1 and day-16 of storage than the NEGCON and PPPM diets, whereas TBARS levels were lowest (p < 0.05) in PPPM6 meat on day-16. The gut pH, histology, haematology, serum-biochemical indices, and bone quality parameters of Cobb 500 broiler birds fed diets supplemented with PPPM was determined. Birds fed POSCON, PPM2 and PPPM4 diets had the lowest (p < 0.05) pH in the duodenum, jejunum, and caecum, whereas duodenal pH values were lowest (p < 0.05) in birds fed PPPM2 and PPPM4 diets compared with birds on NEGCON. Birds fed PPPM4 diet had the highest (p < 0.01) duodenal, jejunal and ileal villi height (VH), and the highest (p < 0.01) VH to crypt depth (CD) ratio in the duodenum, jejunum, and ileum. The lowest (p < 0.05) CD in the duodenum, jejunum and ileum was also recorded in birds fed PPPM4 diet. Birds fed PPPM8 diet had higher (p < 0.05) values for white blood cell count, red blood cell count, haemoglobin concentration and packed cell volume, whereas the lowest (p < 0.05) concentration of serum aspartate transaminase was recorded in birds fed PPPM4 diet. Birds on PPM4 diet had longer (p < 0.05) bones. Bone weight and bone breaking strength were highest (p < 0.05) in birds fed PPPM8 diet. Tibia zinc and iron concentrations increased as the inclusion levels of pomegranate peel powder meal increased. It was concluded that broiler birds require 4 g/kg pomegranate peel powder for enhanced growth performance, nutrient digestibility, gut histology, quality, and antioxidant enzyme activity of meat, whereas 8 g/kg pomegranate peel powder meal supplementation is required for enhanced heamato-biochemical indices, bone quality, fatty acid composition and lipid peroxidative parameters in broiler birds. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Akuru, Eunice Amaka https://orcid.org/0000-0002-3093-0247
- Date: 2022-04
- Subjects: Broilers (Chickens) , Meat -- Quality
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/23611 , vital:58218
- Description: The objective of the current study was to investigate the overall response of broiler birds to varying dietary levels of pomegranate (Punica granatum L) peel powder meal (PPPM). A total of 432-day-old Cobb 500 broiler chicks were randomly divided into six experimental groups of four replications with 18 birds per replicate in a completely randomized design (CRD). The birds were fed isonitrogenous and isocaloric experimental diets designated as: T1-control diet with 0percent additives (negative control; NEGCON); T2- control diet supplemented with α-tocopherol acetate at 200g per ton (positive control; POSCON): T3, T4, T5 and T6-control diet supplemented with 2, 4, 6 and 8g/kg PPPM (PPPM2, PPPM4, PPPM6, PPPM8). The phytochemical, nutritional and antioxidant properties of the pomegranate peel powder were determined. Results showed that the South African-grown pomegranate peel (“Wonderful” variety) had rich protein and trace mineral contents. Higher (p < 0.05) antioxidant and hepatic anti-lipid peroxidative activities were recorded in the ethanol and acetone extracts than the water extract, whereas the three extracts had no toxic effects on liver and kidney cells (p > 0.05). The dietary effects of PPPM supplementation on growth performance, digestibility, carcass, and organ weight indices of Cobb 500 birds were determined. The POSCON diet enhanced (p < 0.05) feed conversion ratio (FCR) at week 3. The average final body weight and average daily weight gain were highest (p < 0.05) in birds fed PPPM2 and PPPM4 diets, whereas birds fed PPPM2 diet had enhanced (p < 0.05) FCR and protein efficiency ratio when compared with birds on POSCON. Thigh and breast weights were highest (p < 0.05) in birds on PPPM4 and PPPM8 diets, whereas birds fed PPPM4 diet had enhanced (p < 0.05) nutrient digestibility compared with those on POSCON. The antioxidant status and breast meat quality of Cobb 500 broiler birds fed diets supplemented with PPPM were determined. Meat from birds fed PPPM8 diet had the highest (p < 0.05) thawing loss, while cooking loss was lowest (p < 0.05) in the PPPM2 group. The highest (p < 0.05) ability to scavenge ABTS [(2, 2-azinobis (3ethylbenzothiazoline-6 sulfonic acid))] radical cation (ABTS+) was recorded in the PPPM2 and PPPM4 meat while PPPM8 meat had increased (p < 0.05) catalase activity. The fatty acid composition, oxidative status, and drip loss in breast meat of Cobb 500 broiler birds fed graded levels of PPPM was determined. Meat from birds fed PPPM4 diet had the lowest (p < 0.05) margaric (C17:0) and arachidic (C20:0) acids, while meat from birds fed PPPM8 diet had higher (p < 0.05) levels of eicosadenoic (C20:2, n-6) and arachidonic (AA, 20:4) acids. The POSCON had higher (p < 0.05) ability to reduce TBARS levels in meat on day-1 and day-16 of storage than the NEGCON and PPPM diets, whereas TBARS levels were lowest (p < 0.05) in PPPM6 meat on day-16. The gut pH, histology, haematology, serum-biochemical indices, and bone quality parameters of Cobb 500 broiler birds fed diets supplemented with PPPM was determined. Birds fed POSCON, PPM2 and PPPM4 diets had the lowest (p < 0.05) pH in the duodenum, jejunum, and caecum, whereas duodenal pH values were lowest (p < 0.05) in birds fed PPPM2 and PPPM4 diets compared with birds on NEGCON. Birds fed PPPM4 diet had the highest (p < 0.01) duodenal, jejunal and ileal villi height (VH), and the highest (p < 0.01) VH to crypt depth (CD) ratio in the duodenum, jejunum, and ileum. The lowest (p < 0.05) CD in the duodenum, jejunum and ileum was also recorded in birds fed PPPM4 diet. Birds fed PPPM8 diet had higher (p < 0.05) values for white blood cell count, red blood cell count, haemoglobin concentration and packed cell volume, whereas the lowest (p < 0.05) concentration of serum aspartate transaminase was recorded in birds fed PPPM4 diet. Birds on PPM4 diet had longer (p < 0.05) bones. Bone weight and bone breaking strength were highest (p < 0.05) in birds fed PPPM8 diet. Tibia zinc and iron concentrations increased as the inclusion levels of pomegranate peel powder meal increased. It was concluded that broiler birds require 4 g/kg pomegranate peel powder for enhanced growth performance, nutrient digestibility, gut histology, quality, and antioxidant enzyme activity of meat, whereas 8 g/kg pomegranate peel powder meal supplementation is required for enhanced heamato-biochemical indices, bone quality, fatty acid composition and lipid peroxidative parameters in broiler birds. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
Pharmacological, toxicological and phytochemical evaluation of helichrysum petiolare hilliard & b.l. burtt - an indigenous plant traditionally used in the treatment of diabetes in the eastern cape province of South Africa
- Aladejana, Adebowale Emmanuel https://orcid.org/0000-0003-1871-926X
- Authors: Aladejana, Adebowale Emmanuel https://orcid.org/0000-0003-1871-926X
- Date: 2022-04
- Subjects: Diabetes -- Alternative treatment , Traditional medicine , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22787 , vital:52755
- Description: Diabetes mellitus is one of the leading causes of death in South Africa, and it has already placed significant stress on the country’s health sector and economy. The orthodox hypoglycaemic drugs are not only ineffective in the management of the disease and its complications, but they also possess unwanted side effects. The need for alternative non-toxic drugs is therefore imperative. Various studies have listed several medicinal plants that can be successfully used in the herbal treatment of diabetes and have investigated them for their anti-diabetic potentials in vivo and/or in vitro. Out of the different potential herbal species, plants belonging to the Asteraceae family possess highly potent hypoglycaemic properties with negligible toxicities. Five Asteraceae plants widely used in different parts of South Africa for the treatment of diabetes were reviewed. The review provided an update of scientific evidence on the hypoglycaemic properties of the plants. However, Helichrysum petiolare was studied extensively in this study for its antidiabetic activity H. petiolare has been listed in many ethnobotanical surveys as a plant with potent hypoglycaemic potential, this, however, has not been properly verified in scientific literature and there has hardly been any study on the essential oil and nutritional composition, and antioxidant, antidiabetic, and cytotoxicity potentials of the plant. The effects of hydro-distillation (HD) and solvent-free microwave extraction (SFME) methods on the chemical constituents of H. petiolare-derived essential oils were evaluated. The SFME method had a higher yield of essential oil than the HD. There were substantial amounts of monoterpenes, monoterpene alcohols, sesquiterpenes, and sesquiterpene alcohols in both essential oils obtained, but these compounds were more profound in the SFME derived essential oil which has 62 compounds compared to the 52 derived through HD. The SFME derived essential oil can therefore be said to be of better quality than the HD method. The compounds obtained in the essential oils have high pharmaceutical and cosmetic value, and as observed in this study, their quantity is dependent on the method of extraction (Ibáñez and Blázquez, 2021; Kaur et al., 2021). The proximate analysis of the whole plant of H. petiolare showed high levels of Acid Detergent Fibre (ADF), vitamins (A, C and E), Neutral Detergent Fibre (NDF), and minerals. The high ADF level is believed to be responsible for the low energy, fat and carbohydrate levels observed in the study. The result showed a high level of oxalate and therefore suggests cooking of the plant before human consumption. Overall nutrition and mineral compositions of the plant showed that H. petiolare is immensely rich in vital nutrients that are of great importance to health and metabolism; these nutrients are suggested to be partly responsible for the plant’s useful medicinal properties. The phytochemical contents of the acetone (ACQ), ethanol (ETQ), and boiled (BAQ) and cold (CAQ) aqueous whole-plant extracts of Helichrysum petiolare were determined using standard phytochemical reaction methods. ABTS, DPPH, NO and TAC assays were used to evaluate their antioxidant properties. The highest total phenolic content (212,963 mg/g) was reported in the BAQ extract, while the ETQ had the highest flavonoid (172.393 mg/g) and proanthocyanidin contents (65.855 mg/g). Alkaloids, flavonols, and saponin were highest in the ACQ extract, while the CAQ had the lowest phytochemical content. Among the extracts, the BAQ had the highest DPPH•+ (IC50 0.02 mg/mL) and ABTS•+ (IC50 0.07) inhibition capacities, while the ETQ exhibited the highest NO• Inhibition (IC50 0.41 mg/mL) and TAC (IC50 0.19 mg/mL). These findings justify the use of H. petiolare in traditional medicine and further recommend the ETQ and BAQ extracts of the plant as more effective extracts for medicinal treatment. The hepatotoxicity (cytotoxicity, mitotoxicity and lipotoxicity) potential of the BAQ, CAQ and ETQ extracts of Helichrysum petiolare was evaluated using standard procedures. The results showed negligible BAQ and CAQ cytotoxicities, which were further, corroborated by stability in the mitochondrial membrane potentials and were congruent with the CAQ and BAQ results for steatosis and phospholipidosis. The data suggested favourable CAQ and BAQ toxicity profiles with limited risks for hepatotoxicity. The ETQ extract, however, showed significantly high levels of cytotoxicity and lipotoxicity, and a low level of mitotoxicity. Our result suggested a potential risk of the ETQ extract for hepatotoxicity but appears partly independent of direct mitochondrial involvement. Glucose uptake assay showed significantly increased glucose uptake in the BAQ and CAQ treated L6 and C3A cell lines. The CAQ extract enhanced glucose uptake more in the L6 myocytes than in the C3A cell-lines hepatocytes. The BAQ extract showed higher levels of inhibition on α–amylase and α-glucosidase activities as compared to CAQ. The BAQ and CAQ extracts of H. petiolare may, therefore, contain pharmacologically active and relatively non-toxic hypoglycaemic chemicals, which may be effective substitutes in the treatment of diabetes mellitus. This study provides up to date scientific information on the use of H. petiolare in the treatment of diabetes mellitus in the Eastern Cape of South Africa. It justifies the use of this plant in herbal medicine and sheds more light on its previously vaguely understood nutritional and medicinal potentials. More studies, however, need to be done to isolate, identify and purify the constituent bioactive compound(s). Their dosage of application and mode of action also needs to be understood. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Aladejana, Adebowale Emmanuel https://orcid.org/0000-0003-1871-926X
- Date: 2022-04
- Subjects: Diabetes -- Alternative treatment , Traditional medicine , Medicinal plants
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/22787 , vital:52755
- Description: Diabetes mellitus is one of the leading causes of death in South Africa, and it has already placed significant stress on the country’s health sector and economy. The orthodox hypoglycaemic drugs are not only ineffective in the management of the disease and its complications, but they also possess unwanted side effects. The need for alternative non-toxic drugs is therefore imperative. Various studies have listed several medicinal plants that can be successfully used in the herbal treatment of diabetes and have investigated them for their anti-diabetic potentials in vivo and/or in vitro. Out of the different potential herbal species, plants belonging to the Asteraceae family possess highly potent hypoglycaemic properties with negligible toxicities. Five Asteraceae plants widely used in different parts of South Africa for the treatment of diabetes were reviewed. The review provided an update of scientific evidence on the hypoglycaemic properties of the plants. However, Helichrysum petiolare was studied extensively in this study for its antidiabetic activity H. petiolare has been listed in many ethnobotanical surveys as a plant with potent hypoglycaemic potential, this, however, has not been properly verified in scientific literature and there has hardly been any study on the essential oil and nutritional composition, and antioxidant, antidiabetic, and cytotoxicity potentials of the plant. The effects of hydro-distillation (HD) and solvent-free microwave extraction (SFME) methods on the chemical constituents of H. petiolare-derived essential oils were evaluated. The SFME method had a higher yield of essential oil than the HD. There were substantial amounts of monoterpenes, monoterpene alcohols, sesquiterpenes, and sesquiterpene alcohols in both essential oils obtained, but these compounds were more profound in the SFME derived essential oil which has 62 compounds compared to the 52 derived through HD. The SFME derived essential oil can therefore be said to be of better quality than the HD method. The compounds obtained in the essential oils have high pharmaceutical and cosmetic value, and as observed in this study, their quantity is dependent on the method of extraction (Ibáñez and Blázquez, 2021; Kaur et al., 2021). The proximate analysis of the whole plant of H. petiolare showed high levels of Acid Detergent Fibre (ADF), vitamins (A, C and E), Neutral Detergent Fibre (NDF), and minerals. The high ADF level is believed to be responsible for the low energy, fat and carbohydrate levels observed in the study. The result showed a high level of oxalate and therefore suggests cooking of the plant before human consumption. Overall nutrition and mineral compositions of the plant showed that H. petiolare is immensely rich in vital nutrients that are of great importance to health and metabolism; these nutrients are suggested to be partly responsible for the plant’s useful medicinal properties. The phytochemical contents of the acetone (ACQ), ethanol (ETQ), and boiled (BAQ) and cold (CAQ) aqueous whole-plant extracts of Helichrysum petiolare were determined using standard phytochemical reaction methods. ABTS, DPPH, NO and TAC assays were used to evaluate their antioxidant properties. The highest total phenolic content (212,963 mg/g) was reported in the BAQ extract, while the ETQ had the highest flavonoid (172.393 mg/g) and proanthocyanidin contents (65.855 mg/g). Alkaloids, flavonols, and saponin were highest in the ACQ extract, while the CAQ had the lowest phytochemical content. Among the extracts, the BAQ had the highest DPPH•+ (IC50 0.02 mg/mL) and ABTS•+ (IC50 0.07) inhibition capacities, while the ETQ exhibited the highest NO• Inhibition (IC50 0.41 mg/mL) and TAC (IC50 0.19 mg/mL). These findings justify the use of H. petiolare in traditional medicine and further recommend the ETQ and BAQ extracts of the plant as more effective extracts for medicinal treatment. The hepatotoxicity (cytotoxicity, mitotoxicity and lipotoxicity) potential of the BAQ, CAQ and ETQ extracts of Helichrysum petiolare was evaluated using standard procedures. The results showed negligible BAQ and CAQ cytotoxicities, which were further, corroborated by stability in the mitochondrial membrane potentials and were congruent with the CAQ and BAQ results for steatosis and phospholipidosis. The data suggested favourable CAQ and BAQ toxicity profiles with limited risks for hepatotoxicity. The ETQ extract, however, showed significantly high levels of cytotoxicity and lipotoxicity, and a low level of mitotoxicity. Our result suggested a potential risk of the ETQ extract for hepatotoxicity but appears partly independent of direct mitochondrial involvement. Glucose uptake assay showed significantly increased glucose uptake in the BAQ and CAQ treated L6 and C3A cell lines. The CAQ extract enhanced glucose uptake more in the L6 myocytes than in the C3A cell-lines hepatocytes. The BAQ extract showed higher levels of inhibition on α–amylase and α-glucosidase activities as compared to CAQ. The BAQ and CAQ extracts of H. petiolare may, therefore, contain pharmacologically active and relatively non-toxic hypoglycaemic chemicals, which may be effective substitutes in the treatment of diabetes mellitus. This study provides up to date scientific information on the use of H. petiolare in the treatment of diabetes mellitus in the Eastern Cape of South Africa. It justifies the use of this plant in herbal medicine and sheds more light on its previously vaguely understood nutritional and medicinal potentials. More studies, however, need to be done to isolate, identify and purify the constituent bioactive compound(s). Their dosage of application and mode of action also needs to be understood. , Thesis (PhD) -- Faculty of Science and Agriculture, 2022
- Full Text:
- Date Issued: 2022-04
Refining predator-prey preference at the prey demographic level for cheetah and lion
- Authors: Annear, Eleesha
- Date: 2022-04
- Subjects: Social behavior in animals --South Africa , Predatory animals –Behavior
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55800 , vital:53880
- Description: Traditional prey preference models estimate prey preference using a coarse species-specific body mass of three-quarters of the mean adult female body mass. This is widely assumed to estimate the average mass across prey populations, accounting for neonates, juveniles, sub-adults, and adults. However, this approach negates the models’ ability to predict demography-specific prey preferences, thus reducing our ability to predict the impacts of predation on prey populations. The objectives of this study were to 1) refine the prey selection models, using lion Panthera leo and cheetah Acinonyx jubatus as model species, by incorporating prey demographic classes and season and, 2) determine the influence of seasonal variability in availability of these prey demographic classes on cheetah reproduction. Lions preferentially killed adults of larger species (e.g., wildebeest, waterbuck, and zebra) irrespective of the season, as predicted by optimal foraging theory. Sub-adult, juvenile, and neonate prey were killed by lions relative to their abundance. Cheetahs preferred juvenile prey of large species, namely kudu, zebra, and wildebeest. Season influenced cheetah preference with neonates and juveniles being preferred during the wet season and adults of smaller species, and juveniles of larger species being preferred during the dry season. Thus, results support the alternative demographic class hypothesis. Furthermore, the availability of neonate and juvenile prey drives cheetah reproduction patterns with conception and cub independence coinciding with the peak availability of easy-to-catch neonates. Lactation coincided with the high availability of relatively larger juveniles to ensure that females obtain enough resources to sustain the most energetically costly reproductive phase. In addition, I suggest cheetah may be particularly vulnerable to disturbances that impact on prey reproduction (e.g., drought, fire, and flood), given their reliance on neonate and juvenile prey. My findings highlight that estimating species-level prey preference using a coarse species-specific body mass masks the level of prey use and potential preferences for the different prey demographic classes. The use of some prey species may be largely confined to juveniles by smaller predators, meaning that prey availability would vary seasonally, may influence reproductive patterns, and carrying capacity models would need to be revised in terms of the available demographic-specific prey biomass. , Thesis (MSc) -- Faculty of Sciences, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Annear, Eleesha
- Date: 2022-04
- Subjects: Social behavior in animals --South Africa , Predatory animals –Behavior
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55800 , vital:53880
- Description: Traditional prey preference models estimate prey preference using a coarse species-specific body mass of three-quarters of the mean adult female body mass. This is widely assumed to estimate the average mass across prey populations, accounting for neonates, juveniles, sub-adults, and adults. However, this approach negates the models’ ability to predict demography-specific prey preferences, thus reducing our ability to predict the impacts of predation on prey populations. The objectives of this study were to 1) refine the prey selection models, using lion Panthera leo and cheetah Acinonyx jubatus as model species, by incorporating prey demographic classes and season and, 2) determine the influence of seasonal variability in availability of these prey demographic classes on cheetah reproduction. Lions preferentially killed adults of larger species (e.g., wildebeest, waterbuck, and zebra) irrespective of the season, as predicted by optimal foraging theory. Sub-adult, juvenile, and neonate prey were killed by lions relative to their abundance. Cheetahs preferred juvenile prey of large species, namely kudu, zebra, and wildebeest. Season influenced cheetah preference with neonates and juveniles being preferred during the wet season and adults of smaller species, and juveniles of larger species being preferred during the dry season. Thus, results support the alternative demographic class hypothesis. Furthermore, the availability of neonate and juvenile prey drives cheetah reproduction patterns with conception and cub independence coinciding with the peak availability of easy-to-catch neonates. Lactation coincided with the high availability of relatively larger juveniles to ensure that females obtain enough resources to sustain the most energetically costly reproductive phase. In addition, I suggest cheetah may be particularly vulnerable to disturbances that impact on prey reproduction (e.g., drought, fire, and flood), given their reliance on neonate and juvenile prey. My findings highlight that estimating species-level prey preference using a coarse species-specific body mass masks the level of prey use and potential preferences for the different prey demographic classes. The use of some prey species may be largely confined to juveniles by smaller predators, meaning that prey availability would vary seasonally, may influence reproductive patterns, and carrying capacity models would need to be revised in terms of the available demographic-specific prey biomass. , Thesis (MSc) -- Faculty of Sciences, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Design, Development and Testing of a Low-cost Sub-Joule μPPT for a PocketQube
- Authors: Bae, Ji Eun
- Date: 2022-04
- Subjects: Electric current converters , Pulse circuits , Plasma jets
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58295 , vital:58953
- Description: Small satellites are unmanned spacecraft with small size and mass weighing less than 500kg. A small satellite called the CubeSat was created by two university professors to help students understand satellite design. The idea of small satellites caught on and they became popular due to their low cost, quick development time and easy deployment. The inexpensive nature of small satellites has helped lower the entry barrier to space and led to a movement called the “democratisation of space”. The popularity of small satellites has also caught the eye of private companies that recognise the potential of commercialising small satellite technologies. Nowadays, small satellites are being considered for more complex and challenging space missions. However for a small satellite to reach its full potential, it needs to be equipped with a proper propulsion system. Governments, space agencies, companies and universities around the world have started to research new innovative miniaturised space propulsion technologies. Nowadays, there are many newly developed miniaturised propulsion technologies available. The new propulsion systems are either sold by the companies and universities at a very high price, or research and development is closely guarded due to the potential commercial value of the propulsion system. Companies and universities have primarily focused on researching and developing top-of-the-line micro-propulsion devices to win lucrative research funds. This has resulted in a lack of research into cheap reliable micropropulsion as there have been no incentives for companies and universities to develop this area. As a result, fund-limited students and individuals have been left behind, defeating the purpose of small satellites. This dissertation focuses on designing and developing a low-cost sub-joule micro-PPT propulsion system for a PocketQube satellite. The first section covers the literature review, which looks at the different space propulsion technologies currently available. The next section covers the micro-PPT propulsion system’s mechanical and electrical design and development process. After the development process, the performance of the prototype is tested using various input parameters, as well as in vacuum conditions and over its lifetime. The test results show that the optimal performance is obtained with an input voltage supply of 5V at a pulse frequency of 0.5Hz, which achieves a minimal impulse bit v of 0.698μNs and thrust range of 0.349~1.071μN. In comparison to the STRaND-1 3U CubeSat’s PPT, performance data show that the developed μPPT propulsion system is a competitive propulsion solution, as it achieves more thrust with similar minimal impulse bit, using only one third of the power consumption. The μPPT propulsion system is able to produce 1980 shots so far, which is far lower relatively than other established PPTs due to the limitations resulting from capacitor failure. , Thesis (MA) -- Faculty of Engineering, the Built Environment, and Technology, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bae, Ji Eun
- Date: 2022-04
- Subjects: Electric current converters , Pulse circuits , Plasma jets
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58295 , vital:58953
- Description: Small satellites are unmanned spacecraft with small size and mass weighing less than 500kg. A small satellite called the CubeSat was created by two university professors to help students understand satellite design. The idea of small satellites caught on and they became popular due to their low cost, quick development time and easy deployment. The inexpensive nature of small satellites has helped lower the entry barrier to space and led to a movement called the “democratisation of space”. The popularity of small satellites has also caught the eye of private companies that recognise the potential of commercialising small satellite technologies. Nowadays, small satellites are being considered for more complex and challenging space missions. However for a small satellite to reach its full potential, it needs to be equipped with a proper propulsion system. Governments, space agencies, companies and universities around the world have started to research new innovative miniaturised space propulsion technologies. Nowadays, there are many newly developed miniaturised propulsion technologies available. The new propulsion systems are either sold by the companies and universities at a very high price, or research and development is closely guarded due to the potential commercial value of the propulsion system. Companies and universities have primarily focused on researching and developing top-of-the-line micro-propulsion devices to win lucrative research funds. This has resulted in a lack of research into cheap reliable micropropulsion as there have been no incentives for companies and universities to develop this area. As a result, fund-limited students and individuals have been left behind, defeating the purpose of small satellites. This dissertation focuses on designing and developing a low-cost sub-joule micro-PPT propulsion system for a PocketQube satellite. The first section covers the literature review, which looks at the different space propulsion technologies currently available. The next section covers the micro-PPT propulsion system’s mechanical and electrical design and development process. After the development process, the performance of the prototype is tested using various input parameters, as well as in vacuum conditions and over its lifetime. The test results show that the optimal performance is obtained with an input voltage supply of 5V at a pulse frequency of 0.5Hz, which achieves a minimal impulse bit v of 0.698μNs and thrust range of 0.349~1.071μN. In comparison to the STRaND-1 3U CubeSat’s PPT, performance data show that the developed μPPT propulsion system is a competitive propulsion solution, as it achieves more thrust with similar minimal impulse bit, using only one third of the power consumption. The μPPT propulsion system is able to produce 1980 shots so far, which is far lower relatively than other established PPTs due to the limitations resulting from capacitor failure. , Thesis (MA) -- Faculty of Engineering, the Built Environment, and Technology, 2022
- Full Text:
- Date Issued: 2022-04
Formulation of methyldopa 250 mg tablets by direct compression using a quality by design approach
- Authors: Baguma, Murungi Isaac
- Date: 2022-04
- Subjects: Pharmaceutical chemistry , Tablets (Medicine)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58575 , vital:59929
- Description: Various pharmaceutical materials are known to take up moisture during both storage and manufacture. This phenomenon, termed hygroscopy, can result in unacceptable levels of moisture, potentially having deleterious effects on product quality, and consequently product efficacy and safety. Drug inefficacy specifically can result in life-threatening complications for the pregnant mother with uncontrolled blood pressure. Marketed as immediate release tablets, methyldopa is an antihypertensive drug commonly used in South Africa to treat hypertensive disorders of pregnancy. Despite being in use for over 50 years, the physicochemical challenges posed by methyldopa remain ever present. Methyldopa is not only significantly hygroscopic, but also prone to oxidative and hydrolytic degradation that can be accelerated by moisture. Poor compression behaviour, another limitation of methyldopa, leaves the formulation scientist with a constellation of formulation hurdles that must be faced, understood and overcome. This is a task that can be tackled using elements of the Quality by Design (QbD) approach. Using this approach, the impact of these phenomena on tablet quality can be better understood and controlled. This study was aimed at using this approach to develop a formulation of methyldopa 250 mg tablets. Direct compression, a simple and moisture-free process, was selected for the manufacture of methyldopa tablets. After careful review of literature and consultation with experts, excipients were selected for the candidate formulation and preliminary concentrations established for each. Similarly, settings for mixing and compression variables were established. Adopted from the QbD framework, the risk posed to tablet quality by these factors was qualitatively analysed using Preliminary Hazard Analysis (PHA) and quantitatively evaluated using Failure Modes and Effect Analysis (FMEA). Eight (8) factors determined to be high risk were further investigated in a preliminary experiment that followed a 12-batch Plackett Burman design. Data from this experiment was used to draw statistical relationships between the aforementioned factors and tablet quality attributes, thus shedding light on excipients and process parameters with practically significant impact on methyldopa tablet quality. Multivariate Analysis of Variance (MANOVA) of the response data reported SSG concentration, citric acid monohydrate xxvii concentration and mixing speed as key factors (p<0.05), demonstrating the need to control these factors for quality targets to be met. These three factors underpinned the 16-batch definitive experiment that followed, conceived using a Box Behnken design (BBD) including four batches prepared at the centerpoint values in the region of experimentation. The optimal methyldopa tablet formulation was achieved at the following settings: 1.0 % m/m magnesium stearate, 1.0 % m/m colloidal silica, 3.9 % m/m sodium starch glycolate, 1.7 % m/m citric acid monohydrate, mixing speed of 101 rpm, 6 minutes of pre-lubrication mixing, 2 minutes of lubrication and compression speed of 20 rpm. These settings were included in the design space and subsequent control strategy. It was learned that, within the design space, the risk to tablet quality and, by extension, the patient, was insignificant. This demonstrated that, using the QbD approach, challenges to pharmaceutical development can be effectively overcome. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Baguma, Murungi Isaac
- Date: 2022-04
- Subjects: Pharmaceutical chemistry , Tablets (Medicine)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/58575 , vital:59929
- Description: Various pharmaceutical materials are known to take up moisture during both storage and manufacture. This phenomenon, termed hygroscopy, can result in unacceptable levels of moisture, potentially having deleterious effects on product quality, and consequently product efficacy and safety. Drug inefficacy specifically can result in life-threatening complications for the pregnant mother with uncontrolled blood pressure. Marketed as immediate release tablets, methyldopa is an antihypertensive drug commonly used in South Africa to treat hypertensive disorders of pregnancy. Despite being in use for over 50 years, the physicochemical challenges posed by methyldopa remain ever present. Methyldopa is not only significantly hygroscopic, but also prone to oxidative and hydrolytic degradation that can be accelerated by moisture. Poor compression behaviour, another limitation of methyldopa, leaves the formulation scientist with a constellation of formulation hurdles that must be faced, understood and overcome. This is a task that can be tackled using elements of the Quality by Design (QbD) approach. Using this approach, the impact of these phenomena on tablet quality can be better understood and controlled. This study was aimed at using this approach to develop a formulation of methyldopa 250 mg tablets. Direct compression, a simple and moisture-free process, was selected for the manufacture of methyldopa tablets. After careful review of literature and consultation with experts, excipients were selected for the candidate formulation and preliminary concentrations established for each. Similarly, settings for mixing and compression variables were established. Adopted from the QbD framework, the risk posed to tablet quality by these factors was qualitatively analysed using Preliminary Hazard Analysis (PHA) and quantitatively evaluated using Failure Modes and Effect Analysis (FMEA). Eight (8) factors determined to be high risk were further investigated in a preliminary experiment that followed a 12-batch Plackett Burman design. Data from this experiment was used to draw statistical relationships between the aforementioned factors and tablet quality attributes, thus shedding light on excipients and process parameters with practically significant impact on methyldopa tablet quality. Multivariate Analysis of Variance (MANOVA) of the response data reported SSG concentration, citric acid monohydrate xxvii concentration and mixing speed as key factors (p<0.05), demonstrating the need to control these factors for quality targets to be met. These three factors underpinned the 16-batch definitive experiment that followed, conceived using a Box Behnken design (BBD) including four batches prepared at the centerpoint values in the region of experimentation. The optimal methyldopa tablet formulation was achieved at the following settings: 1.0 % m/m magnesium stearate, 1.0 % m/m colloidal silica, 3.9 % m/m sodium starch glycolate, 1.7 % m/m citric acid monohydrate, mixing speed of 101 rpm, 6 minutes of pre-lubrication mixing, 2 minutes of lubrication and compression speed of 20 rpm. These settings were included in the design space and subsequent control strategy. It was learned that, within the design space, the risk to tablet quality and, by extension, the patient, was insignificant. This demonstrated that, using the QbD approach, challenges to pharmaceutical development can be effectively overcome. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Foraging behaviour of the Sooty Albatross in relation to climatic variability and fisheries
- Authors: Banda, Shamiso
- Date: 2022-04
- Subjects: Spatial behavior in animals , Conservation of natural resources --South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55632 , vital:53383
- Description: As top predators, seabirds occupy the upper trophic level of marine ecosystems. They are consequently important for the maintenance of ecosystem structure and function, while also possessing characteristics which are useful for identifying climate-driven changes in oceanography at all trophic levels. This important faunal group is one of the most threatened, with climate change and fisheries bycatch mortality being the primary drivers of population declines. Understanding these threats is important for the management of threatened seabird populations. One impact of climate change and variability in climate occurs through changes in prey availability. As central place foragers, breeding seabirds have trip duration constraints due to the obligation of nest duties. This makes them particularly vulnerable to changes in prey availability within their foraging ranges. The ability to adjust foraging behaviour during environmental conditions which alter prey availability is an important attribute which can contribute to breeding success. Thus, investigating for this foraging behavioural plasticity during different breeding stages provides insights into how a species is likely to be impacted by climate change. The sooty albatross population on Marion Island was studied and displayed a degree of foraging behavioural plasticity during the five-year period of pronounced climatic variability studied. Incubating birds mainly foraged in the subtropical convergence zone (STCZ), the Sub Antarctic Front (SAF) and Subtropical Front (STF) which border it, and the region north of the STF. Brooding birds mainly used the SAF and Polar Frontal Zone (PFZ). Significantly different areas were used between years during both breeding stages. This population showed a lack of consistent habitat preferences which may offer resilience to progressive climatic variability and change. Interactions of sooty albatrosses, as well as white-chinned petrels for comparative purposes, with fisheries were also assessed. The two species were compared to shed light on possible explanations for differences in seabird-fishery interactions between the species. The impact of fisheries-related mortality (bycatch) is dependent on exposure to fishing activity and attraction to fishing boats encountered while foraging. Bycatch mortality has previously been proposed as the main cause of this sooty albatross population’s decline. Exposure and 6 attraction to fishing boats was found to be lower than that of white-chinned petrels which are bycatch prone. However, the current level of attraction exhibited by this sooty albatross population may expose a significant fraction of the population to bycatch risk due to its small population size. Additionally, all fishing boats were encountered north of the STF where non breeding individuals are now known to be distributed. Thus, the impact of fisheries on this population may mainly be mediated by more bycatch prone non-breeding individuals. Overall, the relative impact of fisheries bycatch mortality is suggested to be higher than that of climatic impacts on the sooty albatross population on Marion Island. However, this study did not incorporate dietary and demographic information which would reveal whether there are nutritional differences between years that may impact on breeding success. An integrated rather than independent assessment of foraging behavioural responses to climatic variability and fishing activity is recommended for improving our understanding of current and future conservation priorities. , Thesis (MSc) -- Faculty of Science, Zoology , 2021
- Full Text:
- Date Issued: 2022-04
- Authors: Banda, Shamiso
- Date: 2022-04
- Subjects: Spatial behavior in animals , Conservation of natural resources --South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55632 , vital:53383
- Description: As top predators, seabirds occupy the upper trophic level of marine ecosystems. They are consequently important for the maintenance of ecosystem structure and function, while also possessing characteristics which are useful for identifying climate-driven changes in oceanography at all trophic levels. This important faunal group is one of the most threatened, with climate change and fisheries bycatch mortality being the primary drivers of population declines. Understanding these threats is important for the management of threatened seabird populations. One impact of climate change and variability in climate occurs through changes in prey availability. As central place foragers, breeding seabirds have trip duration constraints due to the obligation of nest duties. This makes them particularly vulnerable to changes in prey availability within their foraging ranges. The ability to adjust foraging behaviour during environmental conditions which alter prey availability is an important attribute which can contribute to breeding success. Thus, investigating for this foraging behavioural plasticity during different breeding stages provides insights into how a species is likely to be impacted by climate change. The sooty albatross population on Marion Island was studied and displayed a degree of foraging behavioural plasticity during the five-year period of pronounced climatic variability studied. Incubating birds mainly foraged in the subtropical convergence zone (STCZ), the Sub Antarctic Front (SAF) and Subtropical Front (STF) which border it, and the region north of the STF. Brooding birds mainly used the SAF and Polar Frontal Zone (PFZ). Significantly different areas were used between years during both breeding stages. This population showed a lack of consistent habitat preferences which may offer resilience to progressive climatic variability and change. Interactions of sooty albatrosses, as well as white-chinned petrels for comparative purposes, with fisheries were also assessed. The two species were compared to shed light on possible explanations for differences in seabird-fishery interactions between the species. The impact of fisheries-related mortality (bycatch) is dependent on exposure to fishing activity and attraction to fishing boats encountered while foraging. Bycatch mortality has previously been proposed as the main cause of this sooty albatross population’s decline. Exposure and 6 attraction to fishing boats was found to be lower than that of white-chinned petrels which are bycatch prone. However, the current level of attraction exhibited by this sooty albatross population may expose a significant fraction of the population to bycatch risk due to its small population size. Additionally, all fishing boats were encountered north of the STF where non breeding individuals are now known to be distributed. Thus, the impact of fisheries on this population may mainly be mediated by more bycatch prone non-breeding individuals. Overall, the relative impact of fisheries bycatch mortality is suggested to be higher than that of climatic impacts on the sooty albatross population on Marion Island. However, this study did not incorporate dietary and demographic information which would reveal whether there are nutritional differences between years that may impact on breeding success. An integrated rather than independent assessment of foraging behavioural responses to climatic variability and fishing activity is recommended for improving our understanding of current and future conservation priorities. , Thesis (MSc) -- Faculty of Science, Zoology , 2021
- Full Text:
- Date Issued: 2022-04
Synthesis and applications of novel fluorescent and colorimetric coumarin-based sensors towards analyte sensing in aqueous systems
- Authors: Battison, Aidan Leigh
- Date: 2022-04
- Subjects: Water-supply engineering--Technological innovations , Polymers--Optical properties , Fluorescent polymers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55954 , vital:54558
- Description: The continuous growth of mankind has not been considerate to the environment. The release of millions of tonnes of toxic heavy metal cations and anionic species through industrial, mining, agricultural, and electronic dumping has led to disease and, in many instances, death. This is usually suffered by low-income informal populations residing in third world countries. Moreover, many unnecessary deaths of children are becoming more prevalent because of consumption and contact with contaminated water, agricultural, and animal sources. Bioaccumulation of these toxic species in fish, plants, and animals, inevitably make their way back to the unaware general population. As growth by mining, agriculture, and electronics are indeed vital aspects of human development, the negative side effects of these activities usually continue unregulated. Therefore, as these processes are set to continue until more stringent regulatory processes are put into legislature; low-cost, sensitive, selective organic based sensors are a step in the right direction towards highlighting the need for environmental restoration and remediation; whilst also aiming to preventing unnecessary disease and death in the process. Herein, coumarin derived small-molecule fluorescent and colorimetric sensors for the quantitative and qualitative assessment of cationic and anionic species in aqueous and organic media are described. Ten fluorescent sensors supporting 1,4-disubstituted triazolyl moieties were synthesized according to Cu(I)-catalyzed azide-alkyne cycloaddition “click” reactions. These sensors were screened for their cationic and anionic affinities in a variety of solvent systems. Majority of the sensors responded well towards Fe3+, characterized by a strong fluorescent quenching response with a good degree of sensitivity and selectivity. Selected sensors were further investigated for their affinities towards anionic species; however, they did not display the same degree of selectivity or sensitivity towards these chosen anions. Titration studies of selected sensors with Fe3+ were able to be used towards determining the modes of fluorescent quenching; the photophysical mechanisms by which quenching occurs; stoichiometric binding ratios, association constants, and the number of coordination sites present between the sensors and Fe3+. Reversibility studies of the sensor-metal complex was investigated with EDTA. Partial reversibility was achieved for the chosen sensors with Fe3+. Hydrogen potential studies further described the application of these sensors over a good pH range. The binding site between the sensors and Fe3+ was investigated by NMR studies. , Thesis (PhD) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Battison, Aidan Leigh
- Date: 2022-04
- Subjects: Water-supply engineering--Technological innovations , Polymers--Optical properties , Fluorescent polymers
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55954 , vital:54558
- Description: The continuous growth of mankind has not been considerate to the environment. The release of millions of tonnes of toxic heavy metal cations and anionic species through industrial, mining, agricultural, and electronic dumping has led to disease and, in many instances, death. This is usually suffered by low-income informal populations residing in third world countries. Moreover, many unnecessary deaths of children are becoming more prevalent because of consumption and contact with contaminated water, agricultural, and animal sources. Bioaccumulation of these toxic species in fish, plants, and animals, inevitably make their way back to the unaware general population. As growth by mining, agriculture, and electronics are indeed vital aspects of human development, the negative side effects of these activities usually continue unregulated. Therefore, as these processes are set to continue until more stringent regulatory processes are put into legislature; low-cost, sensitive, selective organic based sensors are a step in the right direction towards highlighting the need for environmental restoration and remediation; whilst also aiming to preventing unnecessary disease and death in the process. Herein, coumarin derived small-molecule fluorescent and colorimetric sensors for the quantitative and qualitative assessment of cationic and anionic species in aqueous and organic media are described. Ten fluorescent sensors supporting 1,4-disubstituted triazolyl moieties were synthesized according to Cu(I)-catalyzed azide-alkyne cycloaddition “click” reactions. These sensors were screened for their cationic and anionic affinities in a variety of solvent systems. Majority of the sensors responded well towards Fe3+, characterized by a strong fluorescent quenching response with a good degree of sensitivity and selectivity. Selected sensors were further investigated for their affinities towards anionic species; however, they did not display the same degree of selectivity or sensitivity towards these chosen anions. Titration studies of selected sensors with Fe3+ were able to be used towards determining the modes of fluorescent quenching; the photophysical mechanisms by which quenching occurs; stoichiometric binding ratios, association constants, and the number of coordination sites present between the sensors and Fe3+. Reversibility studies of the sensor-metal complex was investigated with EDTA. Partial reversibility was achieved for the chosen sensors with Fe3+. Hydrogen potential studies further described the application of these sensors over a good pH range. The binding site between the sensors and Fe3+ was investigated by NMR studies. , Thesis (PhD) -- Faculty of Science, School of Biomecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
The design of a ritual precinct for the Zion Christian Church (ZCC) in the Swartkops Nature Reserve, Gqeberha:
- Authors: Bezuidenhout, Lee Vicky
- Date: 2022-04
- Subjects: Church buildings --South Africa --Port Elizabeth-- Designs and plans , Zionist Christian Church
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57425 , vital:57758
- Description: Man and nature have become disconnected over the years, as man relies more on the advances of the technical age and less on connections to the natural world. Through this disconnect, nature is bearing the consequences and is in a state of decay. As part of the cosmos, the natural envi-ronment is inherently imbued with sacredness; this sacred nature often manifesting itself within the very structure of the earth. Importance is then placed on how we po-sition ourselves and our holy places within their natural environment in order to set a precedent for the rest of our built environments. This treatise positions itself within ecology and the sacred. It focuses on the particulars of sacredscapes and pilgrimages within a context of Afri-can landscapes and African religions. This encompasses both the built and unbuilt elements of sacred architecture as well as sacredscapes through the reflection of cosmic rhythms, manifest order and harmony in order to create a holistic living organism aware of both the “real” and the sacred. Through its roots in holistic design, is sacredscapes align very closely to that of the ecological paradigm and the creation of integrated ecosystems. Sacred place often realised through the continuation of ritual practice. These rituals are a crucial part of African religions and most often find themselves in or associated with their natural environment. Thus, this is where the focus of the treatise lies - in the ritual cleansing ceremonies of the Zion Christian Church carried out in the Swartkops River. Ritual precincts and the creation of sacredscapes as a tool to reintegrate nature into the sacred will be explored. The intervention presents itself as an emergent ecosystemic architecture creating a sacred space, at the water’s edge, imbued with the Afro-Christian narrative of the Zion Christian Church. , Thesis (MArch)-- Faculty of Engineering, the Built Environment and Technology, School of Architecture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bezuidenhout, Lee Vicky
- Date: 2022-04
- Subjects: Church buildings --South Africa --Port Elizabeth-- Designs and plans , Zionist Christian Church
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57425 , vital:57758
- Description: Man and nature have become disconnected over the years, as man relies more on the advances of the technical age and less on connections to the natural world. Through this disconnect, nature is bearing the consequences and is in a state of decay. As part of the cosmos, the natural envi-ronment is inherently imbued with sacredness; this sacred nature often manifesting itself within the very structure of the earth. Importance is then placed on how we po-sition ourselves and our holy places within their natural environment in order to set a precedent for the rest of our built environments. This treatise positions itself within ecology and the sacred. It focuses on the particulars of sacredscapes and pilgrimages within a context of Afri-can landscapes and African religions. This encompasses both the built and unbuilt elements of sacred architecture as well as sacredscapes through the reflection of cosmic rhythms, manifest order and harmony in order to create a holistic living organism aware of both the “real” and the sacred. Through its roots in holistic design, is sacredscapes align very closely to that of the ecological paradigm and the creation of integrated ecosystems. Sacred place often realised through the continuation of ritual practice. These rituals are a crucial part of African religions and most often find themselves in or associated with their natural environment. Thus, this is where the focus of the treatise lies - in the ritual cleansing ceremonies of the Zion Christian Church carried out in the Swartkops River. Ritual precincts and the creation of sacredscapes as a tool to reintegrate nature into the sacred will be explored. The intervention presents itself as an emergent ecosystemic architecture creating a sacred space, at the water’s edge, imbued with the Afro-Christian narrative of the Zion Christian Church. , Thesis (MArch)-- Faculty of Engineering, the Built Environment and Technology, School of Architecture, 2022
- Full Text:
- Date Issued: 2022-04
A Smaller Circle
- Authors: Bhikha, Nasira
- Date: 2022-04
- Subjects: Creative writing (Higher education) South Africa , South African fiction (English) 21st century , Short stories, South African (English) 21st century , Diaries -- Authorship , Autobiography , Short stories, English History and criticism , American fiction History and criticism , Mexican fiction History and criticism
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232427 , vital:49991
- Description: My thesis is a collection of prose forms weaving my identity as a South African woman of colour, my observations of life through personal, cultural and sociological lenses, where traditions are constantly challenged and evolving. The collection focuses on the untold and unresolved, using fiction as a tool of pushback and psychological reflection. I am motivated by writers who use what I would term reflective expressionism to evoke empathy by tapping into innate, universal emotions. In particular Tiff Holland’s vivid telling of family in the novella Betty Superman where she navigates complex relationships, and bell hooks’ memoirs Bone Black: Memories of Girlhood written as poetic vignettes in fluctuating points of view to draw attention to the intricacies of social structures. Joanna Walsh’s Vertigo has strongly influenced my approach to writing through her compelling imagery and use of motif in fragmented prose that delves into the psyche of her characters. I am also inspired by Lidia Yuknavitch’s visceral use of language, identifying with her invitation: “You deserve to sit at the table. The radiance falls on all of us.” , Thesis (MACW) -- Faculty of Humanities, School of Languages, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bhikha, Nasira
- Date: 2022-04
- Subjects: Creative writing (Higher education) South Africa , South African fiction (English) 21st century , Short stories, South African (English) 21st century , Diaries -- Authorship , Autobiography , Short stories, English History and criticism , American fiction History and criticism , Mexican fiction History and criticism
- Language: English
- Type: Master's thesis , text
- Identifier: http://hdl.handle.net/10962/232427 , vital:49991
- Description: My thesis is a collection of prose forms weaving my identity as a South African woman of colour, my observations of life through personal, cultural and sociological lenses, where traditions are constantly challenged and evolving. The collection focuses on the untold and unresolved, using fiction as a tool of pushback and psychological reflection. I am motivated by writers who use what I would term reflective expressionism to evoke empathy by tapping into innate, universal emotions. In particular Tiff Holland’s vivid telling of family in the novella Betty Superman where she navigates complex relationships, and bell hooks’ memoirs Bone Black: Memories of Girlhood written as poetic vignettes in fluctuating points of view to draw attention to the intricacies of social structures. Joanna Walsh’s Vertigo has strongly influenced my approach to writing through her compelling imagery and use of motif in fragmented prose that delves into the psyche of her characters. I am also inspired by Lidia Yuknavitch’s visceral use of language, identifying with her invitation: “You deserve to sit at the table. The radiance falls on all of us.” , Thesis (MACW) -- Faculty of Humanities, School of Languages, 2022
- Full Text:
- Date Issued: 2022-04
Mentoring of women-owning SMEs in the South African construction industry
- Authors: Bingwa, Nelisa
- Date: 2022-04
- Subjects: Construction industry , Small business
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57535 , vital:58059
- Description: Challenges of women-owning small business have been noted in different economic industries globally. This situation is even more prevalent in the construction industry, where women face special challenges connected to their historic exclusion in the industry. Women small and medium enterprises in the construction industry grow slowly, lack crucial skills and industry experience, making it difficult for them to sustain their businesses. In this regard, mentoring has been acknowledged globally as a viable avenue to assist in developing women-owning small businesses and their chosen business careers. Mentoring in South Africa is acknowledged for its ability to develop the skills of small businesses owners. Accordingly, the mentoring approach was embraced by the post-apartheid South African government to eliminate past apartheid-induced socio- economic inequalities to develop women-owning SMEs across complex businesses such as the construction industry. Numerous mentorship policies have been introduced to obviate the challenges experienced by previously discriminated groups such as women to whom small-medium enterprise opportunities in the construction industry were hitherto inaccessible. Despite such ameliorative measures and interventions, women-owning SMEs in the construction industry continue to experience stagnant business growth and relatively higher business failure rates. The purpose of this study, therefore, was to ascertain the enabling conditions necessary for effective mentoring of women-owning small and medium enterprises in the South African construction industry. The study adopted a qualitative interpretivistic approach that provided insights into mentoring experiences and challenges facing women’s small and medium enterprises in the construction industry. Literature was gathered on small businesses with special reference to women small and medium enterprises in construction and by contextualising issues relating to mentoring such enterprises, especially in the construction industry. Data was gathered from interviews with 18 participants using face-to-face interviews and online platforms such as Teams and WhatsApp. Participants included women-owning small businesses whose businesses have been in operation for a minimum of two years and have participated in mentoring at some point during the operation of their business. Data was analysed inductively by means of content and thematic analyses using a combination of manifest, latent and constant comparative content analyse. The results of the interviews showed that the conditions necessary to create an enabling mentoring of women-owning SMEs in the construction industry include: specific policy v development, public and private sector involvement, industry-related mentoring, provision of female role models, increasing public awareness, provision of basic resources to participate, duration of programmes, mentor and mentee commitment and mentors with exceptional characteristics. , Thesis (MA) -- Faculty of Business and Management Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bingwa, Nelisa
- Date: 2022-04
- Subjects: Construction industry , Small business
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57535 , vital:58059
- Description: Challenges of women-owning small business have been noted in different economic industries globally. This situation is even more prevalent in the construction industry, where women face special challenges connected to their historic exclusion in the industry. Women small and medium enterprises in the construction industry grow slowly, lack crucial skills and industry experience, making it difficult for them to sustain their businesses. In this regard, mentoring has been acknowledged globally as a viable avenue to assist in developing women-owning small businesses and their chosen business careers. Mentoring in South Africa is acknowledged for its ability to develop the skills of small businesses owners. Accordingly, the mentoring approach was embraced by the post-apartheid South African government to eliminate past apartheid-induced socio- economic inequalities to develop women-owning SMEs across complex businesses such as the construction industry. Numerous mentorship policies have been introduced to obviate the challenges experienced by previously discriminated groups such as women to whom small-medium enterprise opportunities in the construction industry were hitherto inaccessible. Despite such ameliorative measures and interventions, women-owning SMEs in the construction industry continue to experience stagnant business growth and relatively higher business failure rates. The purpose of this study, therefore, was to ascertain the enabling conditions necessary for effective mentoring of women-owning small and medium enterprises in the South African construction industry. The study adopted a qualitative interpretivistic approach that provided insights into mentoring experiences and challenges facing women’s small and medium enterprises in the construction industry. Literature was gathered on small businesses with special reference to women small and medium enterprises in construction and by contextualising issues relating to mentoring such enterprises, especially in the construction industry. Data was gathered from interviews with 18 participants using face-to-face interviews and online platforms such as Teams and WhatsApp. Participants included women-owning small businesses whose businesses have been in operation for a minimum of two years and have participated in mentoring at some point during the operation of their business. Data was analysed inductively by means of content and thematic analyses using a combination of manifest, latent and constant comparative content analyse. The results of the interviews showed that the conditions necessary to create an enabling mentoring of women-owning SMEs in the construction industry include: specific policy v development, public and private sector involvement, industry-related mentoring, provision of female role models, increasing public awareness, provision of basic resources to participate, duration of programmes, mentor and mentee commitment and mentors with exceptional characteristics. , Thesis (MA) -- Faculty of Business and Management Sciences, 2022
- Full Text:
- Date Issued: 2022-04
The determinants of loan delinquency among co-operative financial institutions in South Africa
- Authors: Bixa, Sisipho
- Date: 2022-04
- Subjects: Financial institutions -- South Africa , Loans
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57546 , vital:58064
- Description: The world's attention has been drawn to co-operatives since the 2008 financial crisis because of their resilience and ability to prosper in adverse economic situations. Co-operatives, particularly Co-operative Financial Institutions (CFIs), have increased their participation, proving to be a channel for increasing access to finance for the previously unbanked, poverty reduction, and sustained socioeconomic growth across the African continent. Co-operatives have the potential to be a catalyst for long-term growth, which is especially important in a country like South Africa, yet they have been failing owing to loan default. Loan delinquency is a major threat to CFI's ability to continue granting loans to loan applicants and to grow the business. CFIs are unable to recoup the monies they have provided to loan borrowers, as the default rate has steadily increased. This influences the CFIs' financial obligations. The financial growth of CFIs is vital, and failure to keeping cash in circulation has an impact on their fundamental business. In South Africa, CFIs have observed a surge in loan defaults since 2010. Proper loan appraisals, timely reminders of loan recipients' repayments, and escalation on prompt follow-up on loan defaulters all are priorities for CFI management. Despite the efforts of CFIs to reduce delinquency, it has continuously increased. The objective of this study was to figure out what factors influence loan delinquency among CFIs. The study looked at an average of 47 CFIs in South Africa. Another objective of this study was to investigate the extent of loan delinquency among South African CFIs. The study used a quantitative approach, with secondary data obtained from CBDA. Descriptive statistics were used to evaluate the model's goodness of fit. The computed results show that this study has only one-way cross-sectional effects. In this example, the null hypothesis of the Breusch-Pagan (BP) test of "POLS is appropriate" is rejected. According to the descriptive statistics presented in the following section, the null hypothesis of regularly distributed data is not rejected. Pearson correlation was used to determine whether there was a relationship between the control variables and the dependent variable. The least squares regression output from the study was presented in the final section. Finally, GLS regression with random effects was used to examine the relationship between total loan delinquency and the dependent variables. x The research looked at seven independent variables: share league/affiliation, the proportion of women in total membership, youth savings, interest rates, total account receivables, and loan portfolio. However, the results of youth savings, interest rate, and total savings deposits may not be reliable because they are statistically insignificant. According to the study, financial institutions should provide easily accessible and accurate payment methods to encourage borrowers to pay on time. This can be accomplished by creating a website. In addition, CFIs/credit intuitions use a share league/affiliation method to maximize their responsible ownership and investigate why women's membership leads to lower loan delinquency. , Thesis (MA) -- Faculty of Business and Economic science , 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bixa, Sisipho
- Date: 2022-04
- Subjects: Financial institutions -- South Africa , Loans
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57546 , vital:58064
- Description: The world's attention has been drawn to co-operatives since the 2008 financial crisis because of their resilience and ability to prosper in adverse economic situations. Co-operatives, particularly Co-operative Financial Institutions (CFIs), have increased their participation, proving to be a channel for increasing access to finance for the previously unbanked, poverty reduction, and sustained socioeconomic growth across the African continent. Co-operatives have the potential to be a catalyst for long-term growth, which is especially important in a country like South Africa, yet they have been failing owing to loan default. Loan delinquency is a major threat to CFI's ability to continue granting loans to loan applicants and to grow the business. CFIs are unable to recoup the monies they have provided to loan borrowers, as the default rate has steadily increased. This influences the CFIs' financial obligations. The financial growth of CFIs is vital, and failure to keeping cash in circulation has an impact on their fundamental business. In South Africa, CFIs have observed a surge in loan defaults since 2010. Proper loan appraisals, timely reminders of loan recipients' repayments, and escalation on prompt follow-up on loan defaulters all are priorities for CFI management. Despite the efforts of CFIs to reduce delinquency, it has continuously increased. The objective of this study was to figure out what factors influence loan delinquency among CFIs. The study looked at an average of 47 CFIs in South Africa. Another objective of this study was to investigate the extent of loan delinquency among South African CFIs. The study used a quantitative approach, with secondary data obtained from CBDA. Descriptive statistics were used to evaluate the model's goodness of fit. The computed results show that this study has only one-way cross-sectional effects. In this example, the null hypothesis of the Breusch-Pagan (BP) test of "POLS is appropriate" is rejected. According to the descriptive statistics presented in the following section, the null hypothesis of regularly distributed data is not rejected. Pearson correlation was used to determine whether there was a relationship between the control variables and the dependent variable. The least squares regression output from the study was presented in the final section. Finally, GLS regression with random effects was used to examine the relationship between total loan delinquency and the dependent variables. x The research looked at seven independent variables: share league/affiliation, the proportion of women in total membership, youth savings, interest rates, total account receivables, and loan portfolio. However, the results of youth savings, interest rate, and total savings deposits may not be reliable because they are statistically insignificant. According to the study, financial institutions should provide easily accessible and accurate payment methods to encourage borrowers to pay on time. This can be accomplished by creating a website. In addition, CFIs/credit intuitions use a share league/affiliation method to maximize their responsible ownership and investigate why women's membership leads to lower loan delinquency. , Thesis (MA) -- Faculty of Business and Economic science , 2022
- Full Text:
- Date Issued: 2022-04
Zooplankton dynamics of Algoa Bay (South Africa) under varying oceanographic conditions
- Authors: Bizani,Mfundo
- Date: 2022-04
- Subjects: Marine zooplankton -- South Africa , Climate changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55943 , vital:54554
- Description: the ecological significance of ocean plankton in terms of nutrient cycling and energy transfer is widely recognised, as is their mechanistic link with both oceanographic processes and climate. Consequently, plankton are widely regarded as sentinels of climate change, principally owing to their responsiveness to changing environmental conditions. Developing an understanding of the ecological as well as socio-economic consequences associated with changes in marine plankton dynamics has emerged as a key issue worldwide. Though many exciting advances in this respect have been attained with the aid of long-term plankton time series (>50 y), global environmental datasets and innovative meta-analyses, building deep knowledge of regional bio-physical dynamics and responses to specific perturbed states remains an essential component of the collective effort. Algoa Bay, situated on the warmtemperate south-east coast of South Africa presents a unique opportunity to study key elements of plankton ecology relevant to climate change problems in the regional sense. The embayment is locally subjected to frequent wind-driven upwelling and regionally, to periodic mesoscale oceanographic forcing (e.g., large solitary meanders, Agulhas Current intrusions), all of which culminate in a complex physical and biogeochemical environment. Using zooplankton as the focal component and drawing from a multi-year monthly dataset incorporating a bay-scale sampling framework, the present study addressed three key hypotheses pertaining to 1) drivers of spatio-temporal variability, 2) biomass rate of change over temporal scales using time-series analyses, and 3) community responses to a bay-scale biological perturbation event. Zooplankton biomass exhibited prominent seasonal patterns with bimodal peaks corresponding with near-consistent year-to-year autumn and spring blooms. Overall, the spatial trend showed no heterogeneity, though statistical significance between-station variability was noted per season. An analytical framework involving generalised additive models revealed zooplankton spatial heterogeneity in Algoa Bay to be a function of seasonal variation in a suite of physicochemical variables, including the combined effects of temperature, salinity, dissolved oxygen, total nitrogen and silicate, but not ammonium, phosphate or chlorophyll-a (as proxy for phytoplankton). Fronts (including river plumes), warm water intrusion from the Agulhas Current, and wind-driven upwelling were postulated to be key driving forces. Structural breaks analysis performed on station-specific time series revealed significant incremental increases in zooplankton biomass over time, which in turn, corresponded with a gradual decrease in thermocline depth. The most pronounced increasing effect was associated with a period (2013– 14) of amplified land-derived nutrient input and increasing harmful algal bloom (HAB) activity. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bizani,Mfundo
- Date: 2022-04
- Subjects: Marine zooplankton -- South Africa , Climate changes
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55943 , vital:54554
- Description: the ecological significance of ocean plankton in terms of nutrient cycling and energy transfer is widely recognised, as is their mechanistic link with both oceanographic processes and climate. Consequently, plankton are widely regarded as sentinels of climate change, principally owing to their responsiveness to changing environmental conditions. Developing an understanding of the ecological as well as socio-economic consequences associated with changes in marine plankton dynamics has emerged as a key issue worldwide. Though many exciting advances in this respect have been attained with the aid of long-term plankton time series (>50 y), global environmental datasets and innovative meta-analyses, building deep knowledge of regional bio-physical dynamics and responses to specific perturbed states remains an essential component of the collective effort. Algoa Bay, situated on the warmtemperate south-east coast of South Africa presents a unique opportunity to study key elements of plankton ecology relevant to climate change problems in the regional sense. The embayment is locally subjected to frequent wind-driven upwelling and regionally, to periodic mesoscale oceanographic forcing (e.g., large solitary meanders, Agulhas Current intrusions), all of which culminate in a complex physical and biogeochemical environment. Using zooplankton as the focal component and drawing from a multi-year monthly dataset incorporating a bay-scale sampling framework, the present study addressed three key hypotheses pertaining to 1) drivers of spatio-temporal variability, 2) biomass rate of change over temporal scales using time-series analyses, and 3) community responses to a bay-scale biological perturbation event. Zooplankton biomass exhibited prominent seasonal patterns with bimodal peaks corresponding with near-consistent year-to-year autumn and spring blooms. Overall, the spatial trend showed no heterogeneity, though statistical significance between-station variability was noted per season. An analytical framework involving generalised additive models revealed zooplankton spatial heterogeneity in Algoa Bay to be a function of seasonal variation in a suite of physicochemical variables, including the combined effects of temperature, salinity, dissolved oxygen, total nitrogen and silicate, but not ammonium, phosphate or chlorophyll-a (as proxy for phytoplankton). Fronts (including river plumes), warm water intrusion from the Agulhas Current, and wind-driven upwelling were postulated to be key driving forces. Structural breaks analysis performed on station-specific time series revealed significant incremental increases in zooplankton biomass over time, which in turn, corresponded with a gradual decrease in thermocline depth. The most pronounced increasing effect was associated with a period (2013– 14) of amplified land-derived nutrient input and increasing harmful algal bloom (HAB) activity. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Investment promotions within port systems: a case of the port of Ngqura, south Africa
- Authors: Booi, Nozipho
- Date: 2022-04
- Subjects: Investment -- South Africa , Investment analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57601 , vital:58180
- Description: The primary role of ports is to provide an enabling logistical solution for within the transport sector. Ports within South Africa perform this primary role in strict accordance with the National Ports Act 12 of 2005. The liberalisation of economies from closed economies to open economies has impacted the transformation of the transport sector; sea borne trade through ports accounts for 80% of the global trade by volume and 70% by value. Open economies have increased the need for integration of economies and triggered a highly competitive market for ports globally competing for volumes or throughput. To attract volumes, ports need to have sound investment promotions strategies that are responding to market needs. Thus, the primary objective of the research study was to investigate and analyse the various factors that affect investment promotions within the port system, evaluating how these factors can be utilised by the Port of Ngqura to increase volumes and grow market share. Therefore, attention was placed on understanding the value proposition the port has to offer to potential investors to foster FDIs. The researcher employed an interpretivist qualitative research methodology to explore its research aim and objectives. Secondary data in the form of document analysis was used in this research study. The documents analysed are mainly Academic Journals, Policy Documents, Transnet Annual Reports, South African Port Regulator Reports (quarterly and annual reports), Industry Articles, and Published Books. The data collected from secondary sources was analysed through content analysis. The document analysis conducted to understand the determinants of investments at the Port of Ngqura, revealed that the regulatory framework, port costs, availability of infrastructure, connectivity to the hinterland market, safety and security, intermodal transport, and efficiency levels can influence investment promotions within the port, and the determinants can be utilised to increase the volumes at the Port of Ngqura. The research study reviewed the mentioned additional factors such as the speed in responding to enquiries, the packaging of information, the linkages to other development zones and guarantees of secure operations are also determinants that potential investors look for. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Booi, Nozipho
- Date: 2022-04
- Subjects: Investment -- South Africa , Investment analysis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57601 , vital:58180
- Description: The primary role of ports is to provide an enabling logistical solution for within the transport sector. Ports within South Africa perform this primary role in strict accordance with the National Ports Act 12 of 2005. The liberalisation of economies from closed economies to open economies has impacted the transformation of the transport sector; sea borne trade through ports accounts for 80% of the global trade by volume and 70% by value. Open economies have increased the need for integration of economies and triggered a highly competitive market for ports globally competing for volumes or throughput. To attract volumes, ports need to have sound investment promotions strategies that are responding to market needs. Thus, the primary objective of the research study was to investigate and analyse the various factors that affect investment promotions within the port system, evaluating how these factors can be utilised by the Port of Ngqura to increase volumes and grow market share. Therefore, attention was placed on understanding the value proposition the port has to offer to potential investors to foster FDIs. The researcher employed an interpretivist qualitative research methodology to explore its research aim and objectives. Secondary data in the form of document analysis was used in this research study. The documents analysed are mainly Academic Journals, Policy Documents, Transnet Annual Reports, South African Port Regulator Reports (quarterly and annual reports), Industry Articles, and Published Books. The data collected from secondary sources was analysed through content analysis. The document analysis conducted to understand the determinants of investments at the Port of Ngqura, revealed that the regulatory framework, port costs, availability of infrastructure, connectivity to the hinterland market, safety and security, intermodal transport, and efficiency levels can influence investment promotions within the port, and the determinants can be utilised to increase the volumes at the Port of Ngqura. The research study reviewed the mentioned additional factors such as the speed in responding to enquiries, the packaging of information, the linkages to other development zones and guarantees of secure operations are also determinants that potential investors look for. , Thesis (MA) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
Cannabidiol: extraction and purification using flow Chemistry
- Authors: Bopape, Karabo
- Date: 2022-04
- Subjects: Supercritical fluid extraction -- South Africa , Cannabis -- Therapeutic use
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55723 , vital:53410
- Description: cannabinoids are of growing interest in research and pharmaceutical applications. Cannabidiol, which is a non-psychoactive cannabinoid, has many pharmaceutical applications. The current and main source of cannabidiol and other cannabinoids is from cannabis and hemp extractions. Current extraction methods involve the use of conventional solvent extraction, which employs the use of organic solvents, in some cases along with mechanical assistance from various equipment. Alternatively, another widely used extraction method is the use of supercritical extraction fluids (SC-CO2 being the most common). An alternative method, which uses chemical synthesis to derivatize cannabidiol to form an intermediate, which is crystalline and can easily be isolated from the extract; the crystalline intermediate can then be deprotected back to pure cannabidiol. In this research, we investigated and adapted the crystallisation method (originally employed by Adams) into continuous flow. In this research, hemp extracts and oilsrich in CBD were used as the source for cannabidiol. This synthesis was adapted into microreactors to synthesise the crystalline intermediate ester product (cannabidiol-3,5-bis-benzoate) which was subsequently reacted in a saponification ester hydrolysis to convert back and isolate pure CBD using continuous flow microreactor technology. Chapter one gives a comprehensive literature review and background on cannabidiol, along with its chemistry and pharmacological benefits in addition to a brief introduction to continuous flow technology with its advantages. Chapter two details the experimental procedures utilised for both batch and continuous flow syntheses. The continuous flow synthesis and subsequent hydrolysis of the ester intermediate, which shows the improvements in comparison to batch; giving higher product recovery (63% CBD), in shorter reaction times (2.5 min for CBD bis-benzoate; 30 min for CBD) is subsequently presented. This is expanded in chapter three with detailed discussions of the results attained during the continuous flow. The concluding remarks, the impact of this study and future work are elucidated in chapter four. , Thesis (MSc) -- Faculty of Science, Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bopape, Karabo
- Date: 2022-04
- Subjects: Supercritical fluid extraction -- South Africa , Cannabis -- Therapeutic use
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/55723 , vital:53410
- Description: cannabinoids are of growing interest in research and pharmaceutical applications. Cannabidiol, which is a non-psychoactive cannabinoid, has many pharmaceutical applications. The current and main source of cannabidiol and other cannabinoids is from cannabis and hemp extractions. Current extraction methods involve the use of conventional solvent extraction, which employs the use of organic solvents, in some cases along with mechanical assistance from various equipment. Alternatively, another widely used extraction method is the use of supercritical extraction fluids (SC-CO2 being the most common). An alternative method, which uses chemical synthesis to derivatize cannabidiol to form an intermediate, which is crystalline and can easily be isolated from the extract; the crystalline intermediate can then be deprotected back to pure cannabidiol. In this research, we investigated and adapted the crystallisation method (originally employed by Adams) into continuous flow. In this research, hemp extracts and oilsrich in CBD were used as the source for cannabidiol. This synthesis was adapted into microreactors to synthesise the crystalline intermediate ester product (cannabidiol-3,5-bis-benzoate) which was subsequently reacted in a saponification ester hydrolysis to convert back and isolate pure CBD using continuous flow microreactor technology. Chapter one gives a comprehensive literature review and background on cannabidiol, along with its chemistry and pharmacological benefits in addition to a brief introduction to continuous flow technology with its advantages. Chapter two details the experimental procedures utilised for both batch and continuous flow syntheses. The continuous flow synthesis and subsequent hydrolysis of the ester intermediate, which shows the improvements in comparison to batch; giving higher product recovery (63% CBD), in shorter reaction times (2.5 min for CBD bis-benzoate; 30 min for CBD) is subsequently presented. This is expanded in chapter three with detailed discussions of the results attained during the continuous flow. The concluding remarks, the impact of this study and future work are elucidated in chapter four. , Thesis (MSc) -- Faculty of Science, Biomolecular and Chemical Sciences, 2022
- Full Text:
- Date Issued: 2022-04
The design of a 21st century administrative headquarters for the city of Gqeberha
- Authors: Borchers, Spencer Phillip
- Date: 2022-04
- Subjects: Municipal buildings -- South Africa -- Gqeberha -- Designs and plans , Architecture, Modern -- 20th century -- Designs and plans
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57443 , vital:57870
- Description: This treatise developed through an interest in 21st century office buildings and the impact they have on the well-being of occupants. The office of the 20th century disregarded well-being and was focused on efficiently accommodating the functions of the workplace in an effort to increase productivity. Today, many of these buildings inadequately provide for the basic biological, psychological, and social needs required for the work force of the 21 st century. The nature of the office has shifted to a more socially interactive and flexible environment which attempts to obtain productivity targets through nurturing the well-being of occupants. Research has determined that biological health can be supported through the optimization of building performance; psychological health can be supported through considering environmental psychology; and social health can be supported through instilling a robust corporate culture. This treatise takes a qualitative research approach to thoroughly interpret the informants and constraints of the site in order to design additions and alterations to the existing administrative headquarters for the Nelson Mandela Bay Municipality. The updated facility will consolidate the administrative functions of local government into one 21st century administrative headquarters, located on the sites of three current NMBM offices in Govan Mbeki Avenue. , Thesis (MArch) -- Faculty of Engineering, the Built Environment and Technology, School of Architecture, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Borchers, Spencer Phillip
- Date: 2022-04
- Subjects: Municipal buildings -- South Africa -- Gqeberha -- Designs and plans , Architecture, Modern -- 20th century -- Designs and plans
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/57443 , vital:57870
- Description: This treatise developed through an interest in 21st century office buildings and the impact they have on the well-being of occupants. The office of the 20th century disregarded well-being and was focused on efficiently accommodating the functions of the workplace in an effort to increase productivity. Today, many of these buildings inadequately provide for the basic biological, psychological, and social needs required for the work force of the 21 st century. The nature of the office has shifted to a more socially interactive and flexible environment which attempts to obtain productivity targets through nurturing the well-being of occupants. Research has determined that biological health can be supported through the optimization of building performance; psychological health can be supported through considering environmental psychology; and social health can be supported through instilling a robust corporate culture. This treatise takes a qualitative research approach to thoroughly interpret the informants and constraints of the site in order to design additions and alterations to the existing administrative headquarters for the Nelson Mandela Bay Municipality. The updated facility will consolidate the administrative functions of local government into one 21st century administrative headquarters, located on the sites of three current NMBM offices in Govan Mbeki Avenue. , Thesis (MArch) -- Faculty of Engineering, the Built Environment and Technology, School of Architecture, 2022
- Full Text:
- Date Issued: 2022-04
Impacts of algal blooms in a temperate Estuarine fish nursery area, South Africa
- Authors: Bornman, Eugin
- Date: 2022-04
- Subjects: Cyanobacterial toxins --Environmental aspects , Estuarine eutrophication --South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55899 , vital:54398
- Description: Anthropogenically-derived eutrophication and Harmful Algal Blooms (HABs) are an increasing threat to estuarine ecosystems globally. The rapid population growth in coastal areas and the mismanagement of water resources have led to the rapid increase in eutrophication in estuaries. Consequently, HABs have become frequent phenomena with severe impacts on the ecological functioning of these systems. A paucity exists in understanding the specific mechanisms of how HABs impact estuarine communities globally. This has not been studied in South Africa, despite the observed increase in the occurrence of HABs in the past few decades. Therefore, this study investigated the impact of HABs on the ecological functioning of the anthropogenically altered Sundays Estuary, South Africa, which is affected by predictable and recurrent HABs of the raphidophyte, Heterosigma akashiwo. This study found that a high density (> 1000 cell m L-1 ) of H. akashiwo was present during all but the winter months in the poly- to mesohaline zone, yet it peaked in warmer spring/summer months with a density of ca. 70 000 cell m L-1 corresponding to 800 µg Chl-a L -1 . This species significantly altered the estuary's water quality, causing supersaturated surface- and hypoxic bottom-water during severe HABs or referred to as hypereutrophic bloom phases (> 60 µg Chl-a L -1 ). Despite these changes, the common copepod, Pseudodiaptomus hessei, occurred at similar densities among HAB phases and responded to similar triggers to the HAB. However, a shift in predator-prey interactions within the zooplankton community was evident, with scavenger or opportunist species such as the isopod, Cirolana fluviatilis, and the polychaete, Perinereis falsovariegata, occurring at higher densities during hypereutrophic bloom phases. The overall abundance of juvenile and small adult fishes were high during HABs, but the diversity decreased during HABs. Some species, notably the Mugilidae occurred at lower densities during HABs. Mugilidae also had pronounced histological gill alterations and a lowered proportion of secondary lamellae available for gas exchange during an in situ cage experiment where fishes were isolated inside and outside the HAB. Deformities such as tumorous growths were also found for the first time in a South African Estuary. This indicated a stressed population of Mugilidae in the Sundays Estuary. The ubiquitous mugilid, Mugil cephalus, actively avoided HABs during an acoustic telemetry study, despite having a home range that overlapped the HAB area. Tagged individuals mostly occupied areas directly above the HAB in the upper mesohaline to lower oligohaline zones and only iv briefly transitioned through the HAB area to utilise the lower reaches of the estuary. Since the formation of HABs is reliant on various factors, including specific species responses, environmental variables, nutrient enrichment, and flow characteristics, the impacts of HABs on estuarine communities may vary between estuarine systems or affected species. Therefore, more research that focuses on the impacts of HABs on estuaries is needed to limit the potential loss of ecosystem services. Particularly in light of further unsustainable development, upstream freshwater abstraction and climate change, will cause more frequent and severe HABs, that may result in fish population declines in the long-term. Better management and mitigation strategies are needed to reduce HAB formation such as reducing nutrient enrichment and restoring natural freshwater flow and flooding events to the Sundays Estuary. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Bornman, Eugin
- Date: 2022-04
- Subjects: Cyanobacterial toxins --Environmental aspects , Estuarine eutrophication --South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55899 , vital:54398
- Description: Anthropogenically-derived eutrophication and Harmful Algal Blooms (HABs) are an increasing threat to estuarine ecosystems globally. The rapid population growth in coastal areas and the mismanagement of water resources have led to the rapid increase in eutrophication in estuaries. Consequently, HABs have become frequent phenomena with severe impacts on the ecological functioning of these systems. A paucity exists in understanding the specific mechanisms of how HABs impact estuarine communities globally. This has not been studied in South Africa, despite the observed increase in the occurrence of HABs in the past few decades. Therefore, this study investigated the impact of HABs on the ecological functioning of the anthropogenically altered Sundays Estuary, South Africa, which is affected by predictable and recurrent HABs of the raphidophyte, Heterosigma akashiwo. This study found that a high density (> 1000 cell m L-1 ) of H. akashiwo was present during all but the winter months in the poly- to mesohaline zone, yet it peaked in warmer spring/summer months with a density of ca. 70 000 cell m L-1 corresponding to 800 µg Chl-a L -1 . This species significantly altered the estuary's water quality, causing supersaturated surface- and hypoxic bottom-water during severe HABs or referred to as hypereutrophic bloom phases (> 60 µg Chl-a L -1 ). Despite these changes, the common copepod, Pseudodiaptomus hessei, occurred at similar densities among HAB phases and responded to similar triggers to the HAB. However, a shift in predator-prey interactions within the zooplankton community was evident, with scavenger or opportunist species such as the isopod, Cirolana fluviatilis, and the polychaete, Perinereis falsovariegata, occurring at higher densities during hypereutrophic bloom phases. The overall abundance of juvenile and small adult fishes were high during HABs, but the diversity decreased during HABs. Some species, notably the Mugilidae occurred at lower densities during HABs. Mugilidae also had pronounced histological gill alterations and a lowered proportion of secondary lamellae available for gas exchange during an in situ cage experiment where fishes were isolated inside and outside the HAB. Deformities such as tumorous growths were also found for the first time in a South African Estuary. This indicated a stressed population of Mugilidae in the Sundays Estuary. The ubiquitous mugilid, Mugil cephalus, actively avoided HABs during an acoustic telemetry study, despite having a home range that overlapped the HAB area. Tagged individuals mostly occupied areas directly above the HAB in the upper mesohaline to lower oligohaline zones and only iv briefly transitioned through the HAB area to utilise the lower reaches of the estuary. Since the formation of HABs is reliant on various factors, including specific species responses, environmental variables, nutrient enrichment, and flow characteristics, the impacts of HABs on estuarine communities may vary between estuarine systems or affected species. Therefore, more research that focuses on the impacts of HABs on estuaries is needed to limit the potential loss of ecosystem services. Particularly in light of further unsustainable development, upstream freshwater abstraction and climate change, will cause more frequent and severe HABs, that may result in fish population declines in the long-term. Better management and mitigation strategies are needed to reduce HAB formation such as reducing nutrient enrichment and restoring natural freshwater flow and flooding events to the Sundays Estuary. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
The foraging ecology of female Cape fur seals (Arctocephalus pusillus pusillus) in South Africa
- Botha, Jonathan Aubrey, Kirkman, Stephen, Lombard, Amanda
- Authors: Botha, Jonathan Aubrey , Kirkman, Stephen , Lombard, Amanda
- Date: 2022-04
- Subjects: Seals (Animals)--Habitat—Conservation , Marine ecology—South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55965 , vital:54559
- Description: The marine environment is spatially and temporally dynamic and many marine ecosystems are experiencing impacts of broad-scale climate change. Within these ecosystems, marine predators play a crucial role in ecosystem function through their top-down influences on prey populations. These predators may also respond to bottom-up influences and changes at lower trophic levels. A thorough understanding of marine predator foraging ecology is thus important to improve our understanding of ecosystem function, inform conservation and management measures, and to predict the response of predators to future environmental change. The Cape fur seal (Arctocephalus pusillus pusillus) comprises a major proportion of the southern African marine predator biomass. However, little is known about the foraging distribution and behaviour of the species, despite its obvious importance within the ecosystem and increasing concerns regarding seal-fisheries conflict. Using a variety of technologies, including, GPS and satellite-linked tags, dive behaviour recorders, accelerometers and stable isotope analysis, this thesis investigated the foraging ecology of female Cape fur seals breeding on the coast of South Africa. First, to identify important foraging areas and assess the influence of geographic, temporal and environmental factors on these areas, lactating females from three breeding colonies were fitted with GPS or Argos-linked tracking devices, while individuals from two of these colonies were also fitted with dive behaviour recorders. Results revealed geographic differences in the foraging distributions and ranges of individuals between breeding colonies, which likely reflects a combined influence of ecological setting and density dependant competition. In addition, dive behaviour recorders revealed the occurrence of benthic foraging at both sites where they were deployed, and the dominance of this strategy in some individuals. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04
- Authors: Botha, Jonathan Aubrey , Kirkman, Stephen , Lombard, Amanda
- Date: 2022-04
- Subjects: Seals (Animals)--Habitat—Conservation , Marine ecology—South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/55965 , vital:54559
- Description: The marine environment is spatially and temporally dynamic and many marine ecosystems are experiencing impacts of broad-scale climate change. Within these ecosystems, marine predators play a crucial role in ecosystem function through their top-down influences on prey populations. These predators may also respond to bottom-up influences and changes at lower trophic levels. A thorough understanding of marine predator foraging ecology is thus important to improve our understanding of ecosystem function, inform conservation and management measures, and to predict the response of predators to future environmental change. The Cape fur seal (Arctocephalus pusillus pusillus) comprises a major proportion of the southern African marine predator biomass. However, little is known about the foraging distribution and behaviour of the species, despite its obvious importance within the ecosystem and increasing concerns regarding seal-fisheries conflict. Using a variety of technologies, including, GPS and satellite-linked tags, dive behaviour recorders, accelerometers and stable isotope analysis, this thesis investigated the foraging ecology of female Cape fur seals breeding on the coast of South Africa. First, to identify important foraging areas and assess the influence of geographic, temporal and environmental factors on these areas, lactating females from three breeding colonies were fitted with GPS or Argos-linked tracking devices, while individuals from two of these colonies were also fitted with dive behaviour recorders. Results revealed geographic differences in the foraging distributions and ranges of individuals between breeding colonies, which likely reflects a combined influence of ecological setting and density dependant competition. In addition, dive behaviour recorders revealed the occurrence of benthic foraging at both sites where they were deployed, and the dominance of this strategy in some individuals. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2022
- Full Text:
- Date Issued: 2022-04