Ndiyazi ukuba ndiza kufa njani : ingqokelela yemibongo
- Authors: Mdliva, Mqhubi Given
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , Xhosa poetry -- 21st century , Xhosa poetry -- History and criticism , Diaries -- Authorship , Xhosa fiction -- 21st century
- Language: Xhosa
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178295 , vital:42928
- Description: Le mibongo inyathela kwizinto ezitsarhayo; ukufa, ukukhula kweziganeko ezingobundlobongela obuphathelele kwezesondo nesini, kubulawa abantwana namanina ngamadoda norhwaphilizo olugqugqisayo. Lo msebenzi uphonononga ukwavavanya ukusetyenziswa kweempawu zokubhala kungalandelwa miqathango yokubhala koko kusetyenziswa ezi mpawu njengezixhobo zokuphuhlisa iimvakalelo zembongi. Ezi mpawu ziquka iidesh, iikholoni, iisemikholoni ukuqelelaniswa kwamagama kukwashiywa nezikhewu phakathi kwamagama kukhokelwa ngumoya wemibongo. Oku kubangele ukuba le mibongo ibe nezakhiwo ezahlukileyo nezingaqhelekanga kubhalo lwesiXhosa. Oko kukuthi, lo msebenzi utyebisa uncwadi lwesiXhosa ngokukwandisa kule ndlela ingaqhelekanga yokubhala. Umsebenzi kaSt E.P. Yako ube nefuthe kakhulu kulo msebenzi, ngakumbi indlela alusebenzise ngayo ulwimi oluteketeke zizafobe nemifanekiso ukubhala imibongo njengoko enzile kumbongo othi, Izibongo zikaMhlekazi uArchie Sandile. Kumbhali uMarina Tsvetaete kubolekwe indlela ayisebenzise ngayo imifanekiso kumbongo osihloko sithi, Poems for Block kuba udubula ngegama uthi thaa umfanekiso kwingqondo yomfundi. Isimbo sokuyila isakhiwo sombongo sikaSimphiwe Nolutshungu naso sibe nefuthe kule mibongo, kwaye le thisisi yandisa apho lo kaNolutshungu aphele khona ngakumbi kwindlela asebenzise ngayo iimpawu zokubhala. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mdliva, Mqhubi Given
- Date: 2021-04
- Subjects: Creative writing (Higher education) -- South Africa , Xhosa poetry -- 21st century , Xhosa poetry -- History and criticism , Diaries -- Authorship , Xhosa fiction -- 21st century
- Language: Xhosa
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/178295 , vital:42928
- Description: Le mibongo inyathela kwizinto ezitsarhayo; ukufa, ukukhula kweziganeko ezingobundlobongela obuphathelele kwezesondo nesini, kubulawa abantwana namanina ngamadoda norhwaphilizo olugqugqisayo. Lo msebenzi uphonononga ukwavavanya ukusetyenziswa kweempawu zokubhala kungalandelwa miqathango yokubhala koko kusetyenziswa ezi mpawu njengezixhobo zokuphuhlisa iimvakalelo zembongi. Ezi mpawu ziquka iidesh, iikholoni, iisemikholoni ukuqelelaniswa kwamagama kukwashiywa nezikhewu phakathi kwamagama kukhokelwa ngumoya wemibongo. Oku kubangele ukuba le mibongo ibe nezakhiwo ezahlukileyo nezingaqhelekanga kubhalo lwesiXhosa. Oko kukuthi, lo msebenzi utyebisa uncwadi lwesiXhosa ngokukwandisa kule ndlela ingaqhelekanga yokubhala. Umsebenzi kaSt E.P. Yako ube nefuthe kakhulu kulo msebenzi, ngakumbi indlela alusebenzise ngayo ulwimi oluteketeke zizafobe nemifanekiso ukubhala imibongo njengoko enzile kumbongo othi, Izibongo zikaMhlekazi uArchie Sandile. Kumbhali uMarina Tsvetaete kubolekwe indlela ayisebenzise ngayo imifanekiso kumbongo osihloko sithi, Poems for Block kuba udubula ngegama uthi thaa umfanekiso kwingqondo yomfundi. Isimbo sokuyila isakhiwo sombongo sikaSimphiwe Nolutshungu naso sibe nefuthe kule mibongo, kwaye le thisisi yandisa apho lo kaNolutshungu aphele khona ngakumbi kwindlela asebenzise ngayo iimpawu zokubhala. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
- Full Text:
- Date Issued: 2021-04
Softboi
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mall, Shireen
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164373 , vital:41113
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2020
- Full Text:
- Date Issued: 2020
Selection for improved virulence of Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) to False Codling Moth, Thaumatotibia leucotreta, by serial passage through a heterologous host
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Iita, Petrus Paulus
- Date: 2021-04
- Subjects: Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Baculoviruses , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178180 , vital:42918
- Description: The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae) is endemic to southern Africa, and strongly associated with citrus. As South African citrus production is mainly for export to foreign markets, the market access risk due to the phytosanitary status of this pest is considerable and its control is therefore imperative. Various control measures as part of a rigorous integrated pest management (IPM) programme targeted against T. leucotreta have been effective at suppressing the pest in citrus, but there is still a growing need for continued improvement of the programme and augmentation of the available control options. Of these control options, biological control, particularly the use of Cryptophlebia leucotreta granulovirus (CrleGV-SA), is a key component of IPM in citrus orchards and it has been very successful at reducing T. leucotreta populations in the field for almost two decades. There is however, a growing need for more baculovirus variants with an improved virulence against T. leucotreta for a more efficient pest management system. The newly identified insect virus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV) offers a unique opportunity for an additional biopesticide in IPM for control of T. leucotreta in the field. This study aimed to conduct serial passaging of CrpeNPV through a heterologous host, T. leucotreta, in order to determine the potential for improved virulence or speed of kill against it. In order to select for a variant of CrpeNPV with improved virulence against T. leucotreta, a high dose (LC90) of the virus OBs was used to perform 12 serial passages through T. leucotreta larvae in surface-dose bioassays. Whole genome sequencing and analysis of the passaged virus, along with restriction endonuclease profiling in silico was performed to determine if the genetic identity of the virus had changed during serial passage, in relation to the original virus. These analyses indicated that the dominant genotype of CrpeNPV was maintained following 12 serial passages through the heterologous host. The biological activity of the passaged virus, along with the original virus was evaluated against neonate T. leucotreta in surface-dose bioassays and compared. Results from dose-response bioassays showed that the virulence of CrpeNPV did not improve after 12 serial passages. The LC50 values of the passaged virus and the original virus were estimated at 1.96 × 104 and 1.58 × 104 OBs/ml, respectively, whereas the LC90 values were estimated at 3.46 × 104 OBs/ml for the passaged virus and 3.68 × 104 for the original virus. Similarly, the results from time-response bioassays showed that the speed of kill of CrpeNPV did not improve after 12 serial passages. The LT50 values of the passaged virus and the original virus were 88.44 hours (3 days and 16 hours) and 83.74 hours (3 days and 12 hours), respectively, whereas the LT90 values were 115 hours (4 days 19 hours) for the passaged virus and 102 hours (4 days 6 hours) for the original virus. The virulence and speed of kill of the passaged virus decreased significantly, in relation to the original virus. When the full genome of the passaged virus was sequenced and analysed, only a few SNPs were detected in the viral genome, in comparison to the original virus. No detectable difference in REN digestion patterns were observed following REN analysis of gDNA of the passaged virus with several restriction enzymes in silico. The results for this study suggest that CrpeNPV may already be optimally suited to the heterologous host as it persists under these conditions without significant changes to the genome. These results have positive implications for the genetic integrity of CrpeNPV as a potential biocontrol agent in the field. This study is the first to report the virulence selection of CrpeNPV by serial passage through a heterologous host, and also the first to record bioassay data in terms of dose response (or lethal concentration) against T. leucotreta second instars. The data obtained have added to the knowledge about interactions between CrpeNPV and its heterologous host, and may be fundamental to continued investigation into the effect of serial passage on pathogenicity and genetic diversity of CrpeNPV. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
Development and assessment of a fixed dose combination of perindopril arginine and indapamide loaded microparticles
- Authors: Mandava, Tavonga Tyomai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164413 , vital:41116
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
- Authors: Mandava, Tavonga Tyomai
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164413 , vital:41116
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020
An evaluation of the cytotoxic activities of novel artemisinin derivatives: towards targeted therapies for triple-negative breast cancers (TNBC)
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Kajewole, Deborah Ifeoluwa
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/163329 , vital:41029 , doi:10.21504/10962/163329
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Biochemistry and Microbiology, 2020.
- Full Text:
- Date Issued: 2020
Homecoming
- Authors: Mazwai, Nontsikelelo
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164930 , vital:41185
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2017
- Full Text:
- Date Issued: 2017
- Authors: Mazwai, Nontsikelelo
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MA
- Identifier: http://hdl.handle.net/10962/164930 , vital:41185
- Description: Thesis (MA)--Rhodes University, Faculty of Humanities, School of Languages, 2017
- Full Text:
- Date Issued: 2017
CO2-induced woody thickening depends strongly on interacting abiotic and biotic factors
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text:
- Date Issued: 2020
- Authors: Raubenheimer, Sarah Lynn
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164646 , vital:41151 , doi:10.21504/10962/164646
- Description: Thesis (PhD)--Rhodes University, Faculty of Science, Botany, 2020
- Full Text:
- Date Issued: 2020
The effect of various substrate pretreatment methods on the enzymatic degradability of a Eucalyptus sp. – a potential feedstock for producing fermentable sugars
- Authors: Thoresen, Mariska
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178580 , vital:42952
- Description: Access restricted until April 2022. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Thoresen, Mariska
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178580 , vital:42952
- Description: Access restricted until April 2022. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
The further development, application and evaluation of a sediment yield model (WQSED) for catchment management in African catchments
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Gwapedza, David
- Date: 2021-04
- Subjects: Sedimentation and deposition -- South Africa , Sedimentation and deposition -- Zimbabwe , Watersheds -- South Africa , Watersheds -- Zimbabwe , Watershed management -- Africa , Water quality -- South Africa , Water quality -- Zimbabwe , Modified Universal Soil Loss Equation (MUSLE) , Water Quality and Sediment Model (WQSED) , Soil and Water Assessment Tool (SWAT)
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/178376 , vital:42934 , 10.21504/10962/178376
- Description: Erosion and sediment transport are natural catchment processes that play an essential role in ecosystem functioning by providing habitat for aquatic organisms and contributing to the health of wetlands. However, excessive erosion and sedimentation, mostly driven by anthropogenic activity, lead to ecosystem degradation, loss of agricultural land, water quality problems, reduced reservoir storage capacity and damage to physical infrastructure. It is reported that up to 25% of dams in South Africa have lost approximately 30% of their initial storage capacity to sedimentation. Therefore, excessive sedimentation transcends from an ecological problem to a health, livelihood and water security issue. Erosion and sedimentation occur at variable temporal and spatial scales; therefore, monitoring of these processes can be difficult and expensive. Regardless of all these prohibiting factors, information on erosion and sediment remains an urgent requirement for the sustainable management of catchments. Models have evolved as tools to replicate and simulate complex natural processes to understand and manage these systems. Several models have been developed globally to simulate erosion and sediment transport. However, these models are not always applicable in Africa because 1) the conditions under which they were developed are not as relevant for African catchments 2) they have high data requirements and cannot be applied with ease in our data-scarce African catchments 3) they are sometimes complicated, and there are little training available or potential users simply have no time to dedicate towards learning these models. To respond to the problems of erosion, sedimentation, water quality and unavailability of applicable models, the current research further develops, applies and evaluates an erosion and sediment transport model, the Water Quality and Sediment Model (WQSED), for integration within the existing water resources framework in South Africa and application for practical catchment management. The WQSED was developed to simulate daily suspended sediment loads that are vital for water quality and quantity assessments. The WQSED was developed based on the Modified Universal Soil Loss Equation (MUSLE), and the Pitman model is a primary hydrological model providing forcing data, although flow data from independent sources may be used to drive the WQSED model. The MUSLE was developed in the United States of America, and this research attempts to improve the applicability of the MUSLE by identifying key issues that may impede its performance. Assessments conducted within the current research can be divided into scale assessment and application and evaluation assessment. The scale assessment involved evaluating spatial and temporal scale issues associated with the MUSLE. Spatial scale assessments were conducted using analytical and mathematical assessments on a hypothetical catchment. Temporal scale issues were assessed in terms of the vegetation cover (C) factor within the Tsitsa River catchment in South Africa. Model application and evaluation involved applying and calibrating the model to simulate daily time-series sediment yield. The model was applied to calibrated and validated (split-sample validation) in two catchments in South Africa, two catchments in Zimbabwe and three catchments were selected from the USA and associated territories for further testing as continuous daily time-series observed sediment data could not be readily accessed for catchments in the Southern African region. The catchments where the model was calibrated and validated range in size from 50 km2 to 20 000 km2. Additionally, the model was applied to thirteen ‘ungauged’ catchments selected from across South Africa, where only long-term reservoir sedimentation rates were available to compare with long term model simulations converted to sediment yield rates. The additional thirteen catchments were selected from areas of different climatic, vegetation and soils conditions characterising South Africa and range in size from 30 km2 to 2 500 km2. The current research results are split into a) MUSLE scale dependency and b) WQSED testing and evaluation. Scale dependency testing showed that the MUSLE could be spatially scale-dependent, particularly when a lumped approach is used, resulting in simulations of up to 30% more sediment. Spatial scale dependence in the MUSLE was found to be related to the runoff and topographic factors used and how they are calculated. The current study resorted to adopting a reference grid in applying the MUSLE, followed by scaling up the outputs to the total catchment area. Using a reference grid resulted in a general avoidance of the problem of spatial scale. The adoption of a seasonal vegetation cover factor was shown to significantly account for temporal changes of vegetation cover within a year and reduce over-estimations in sediment output. The temporal scale evaluation demonstrated the uncertainties associated with using a fixed vegetation cover factor in a catchment with variable rainfall and runoff pattern. The WQSED model evaluation showed that the model could be calibrated and validated to provide consistent results. Satisfactory model evaluation statistics were obtained for most catchments to which the model was applied, based on general model evaluation guidelines (Nash Sutcliffe Efficiency and R2 > 0.5). The model also performed generally well compared to established models that had been previously applied in some of the study catchments. The highest sediment yields recorded per country were 153 t km-2 year-1 (Tsitsa River; South Africa), 90 t km-2 year-1 (Odzi River; Zimbabwe) and 340 t km-2 year-1 (Rio Tanama; Puerto Rico). The results also displayed consistent underestimations of peak sediment yield events, partly attributed to sediment emanating from gullies that are not explicitly accounted for in the WQSED model structure. Furthermore, the calibration process revealed that the WQSED storage model is generally challenging to calibrate. An alternative simpler version of the storage model was easier to calibrate, but the model may still be challenging to apply to catchments where calibration data are not available. The additional evaluation of the WQSED simulated sediment yield rates against observed reservoir sediment rates showed a broad range of differences between the simulated and observed sediment yield rates. Differences between WQSED simulated sediment and observed reservoir sediment ranges from a low of 30% to a high of > 40 times. The large differences were partly attributed to WQSED being limited to simulating suspended sediment from sheet and rill processes, whereas reservoir sediment is generated from more sources that include bedload, channel and gully processes. Nevertheless, the model simulations replicated some of the regional sediment yield patterns and are assumed to represent sheet and rill contributions to reservoir sediment in selected catchments. The outcome of this study is an improved WQSED model that has successfully undergone preliminary testing and evaluation. Therefore, the model is sufficiently complete to be used by independent researchers and water resources managers to simulate erosion and sediment transport. However, the model is best applicable to areas where some observed data or regional information are available to calibrate the storage components and constrain model outputs. The report on potential MUSLE scale dependencies is relevant globally to all studies applying the MUSLE model and, therefore, can improve MUSLE application in future studies. The WQSED model offers a relatively simple, effective and applicable tool that is set to provide information to enhance catchment, land and water resources management in catchments of Africa. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-04
The Trope of the Child: Rereading Trauma, Subjectivity and Embodiment in Contemporary Child-Centred African Narratives by Ahmadou Kourouma, Chris Abani, K. Sello Duiker and Yvonne Vera
- Authors: Njovane, Thandokazi
- Date: 2019
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164557 , vital:41134 , doi:10.21504/10962/164557
- Description: Thesis (PhD)--Rhodes University, Humanities, Literary Studies in English, 2019
- Full Text:
- Date Issued: 2019
- Authors: Njovane, Thandokazi
- Date: 2019
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/164557 , vital:41134 , doi:10.21504/10962/164557
- Description: Thesis (PhD)--Rhodes University, Humanities, Literary Studies in English, 2019
- Full Text:
- Date Issued: 2019
Impact of sovereign credit ratings on emerging bond and stock market returns
- Authors: Mkhonto, Zoyisile
- Date: 2021-04
- Subjects: Rating agencies (Finance) , Credit ratings , Bond market
- Language: English
- Type: thesis , text , Masters , MCom
- Identifier: http://hdl.handle.net/10962/177170 , vital:42796
- Description: The primary role of credit rating agencies is to reduce asymmetric information between the parties in a lending relationship. The three major rating agencies have received extensive criticism over the years. These rating agencies have been accused of providing inaccurate ratings which ultimately led to various financial calamities. Late rating action has also been blamed for exacerbating financial and economic cycles. Moreover, there is an argument that emerging markets are unfairly rated in comparison to developed economies. Hence, the reliability and informational value of the assessments provided by credit rating agencies is met with scepticism. Despite these criticisms, rating agencies are characterised as gatekeepers to capital and credit ratings remain essential financial market indicators. Albeit, the literature regarding the impact of sovereign credit ratings on bond and stock markets is inconclusive. This study aims to add to the body of literature and provide insights into the informational value of sovereign credit ratings in emerging markets. More specifically to estimate the relationship between various sovereign credit rating announcements, and bond and stock market returns. Also, to examine whether sovereign credit ratings have a differential impact between bond and stock markets. As well as address the question does it matter who provides the rating? Using an event study, abnormal returns surrounding rating announcements from 2009 to 2019 for 24 emerging markets were analyzed. Firstly, this study concluded that sovereign credit ratings are informative. Secondly, the degree of informativeness differs between the bond and stock markets. Thirdly, an asymmetrical impact was observed between the types of rating announcements. Lastly, that it does matter which rating agency provides the rating because each agency has a unique reputation. The findings of this research have implications on how investors and portfolio managers decide on asset allocation. Furthermore, policymakers may find our investment grade analysis of value when evaluating regulatory reform. It’s recommended that future research refines the event methodology and examines country specific characteristics within each of the emerging markets. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mkhonto, Zoyisile
- Date: 2021-04
- Subjects: Rating agencies (Finance) , Credit ratings , Bond market
- Language: English
- Type: thesis , text , Masters , MCom
- Identifier: http://hdl.handle.net/10962/177170 , vital:42796
- Description: The primary role of credit rating agencies is to reduce asymmetric information between the parties in a lending relationship. The three major rating agencies have received extensive criticism over the years. These rating agencies have been accused of providing inaccurate ratings which ultimately led to various financial calamities. Late rating action has also been blamed for exacerbating financial and economic cycles. Moreover, there is an argument that emerging markets are unfairly rated in comparison to developed economies. Hence, the reliability and informational value of the assessments provided by credit rating agencies is met with scepticism. Despite these criticisms, rating agencies are characterised as gatekeepers to capital and credit ratings remain essential financial market indicators. Albeit, the literature regarding the impact of sovereign credit ratings on bond and stock markets is inconclusive. This study aims to add to the body of literature and provide insights into the informational value of sovereign credit ratings in emerging markets. More specifically to estimate the relationship between various sovereign credit rating announcements, and bond and stock market returns. Also, to examine whether sovereign credit ratings have a differential impact between bond and stock markets. As well as address the question does it matter who provides the rating? Using an event study, abnormal returns surrounding rating announcements from 2009 to 2019 for 24 emerging markets were analyzed. Firstly, this study concluded that sovereign credit ratings are informative. Secondly, the degree of informativeness differs between the bond and stock markets. Thirdly, an asymmetrical impact was observed between the types of rating announcements. Lastly, that it does matter which rating agency provides the rating because each agency has a unique reputation. The findings of this research have implications on how investors and portfolio managers decide on asset allocation. Furthermore, policymakers may find our investment grade analysis of value when evaluating regulatory reform. It’s recommended that future research refines the event methodology and examines country specific characteristics within each of the emerging markets. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-04
A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University
- Authors: Tsope, Lindiwe
- Date: 2021-04
- Subjects: AIDS (Disease) South Africa Makhanda , HIV infections South Africa Makhanda , College students Health and hygiene South Africa Makhanda , Universities and colleges South Africa Makhanda Employees Health and hygiene , Stigma (Social psychology) , AIDS (Disease) Social aspects South Africa Makhanda , HIV infections Social aspects South Africa Makhanda , AIDS (Disease) Psychological aspects , HIV infections Psychological aspects , Health counseling South Africa Makhanda , Discourse analysis, Narrative
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/176894 , vital:42769 , 10.21504/10962/176894
- Description: A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University Research on HIV and AIDS in university settings, especially research exploring the experience of living with the disease, has been minimal. As a response to the knowledge and research gaps, this thesis is a qualitative study involving students and staff living with HIV (LWH) and accessing treatment (ART) at the Rhodes University Health Care Centre. This study explored the personal and social symbolisms as well as meanings attached to living with HIV, through in-depth interviews with ten students and staff living with HIV, all purposively sampled and recruited through the Rhodes University Health Care Centre. Using social constructionism, symbolic interactionism and the theory of biographical disruption, the narratives revealed a positive and inspirational side of living with HIV and AIDS – especially emphasizing that PLWHA do not have to surrender to the deadly narrative of the disease. It became evident that stigma, both internal and external, largely influences illness narratives. Furthermore, the study revealed the social reconstruction of life narratives both in order to understand the illness in terms of past social experiences and to reaffirm the impression that life has a course and the self has a purpose. All participants found that accessing treatment from the Rhodes University Health Care Centre positively influenced their experiences of adherence and reconstruction of narratives. The study indicates that HIV-related interventions in place at the university need to pay more attention to the psychosocial needs of PLWH, involvement of PWLH, as well as keeping up with the continuously changing global HIV narrative. The study argues for more attention to in-depth experiences and personal narratives in HIV and AIDS, and PLWHA education at Rhodes University. , Thesis (PhD) -- Humanities, Department of Sociology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Tsope, Lindiwe
- Date: 2021-04
- Subjects: AIDS (Disease) South Africa Makhanda , HIV infections South Africa Makhanda , College students Health and hygiene South Africa Makhanda , Universities and colleges South Africa Makhanda Employees Health and hygiene , Stigma (Social psychology) , AIDS (Disease) Social aspects South Africa Makhanda , HIV infections Social aspects South Africa Makhanda , AIDS (Disease) Psychological aspects , HIV infections Psychological aspects , Health counseling South Africa Makhanda , Discourse analysis, Narrative
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/176894 , vital:42769 , 10.21504/10962/176894
- Description: A narrative study of students’ and staff’s experiences of living with HIV and AIDS at Rhodes University Research on HIV and AIDS in university settings, especially research exploring the experience of living with the disease, has been minimal. As a response to the knowledge and research gaps, this thesis is a qualitative study involving students and staff living with HIV (LWH) and accessing treatment (ART) at the Rhodes University Health Care Centre. This study explored the personal and social symbolisms as well as meanings attached to living with HIV, through in-depth interviews with ten students and staff living with HIV, all purposively sampled and recruited through the Rhodes University Health Care Centre. Using social constructionism, symbolic interactionism and the theory of biographical disruption, the narratives revealed a positive and inspirational side of living with HIV and AIDS – especially emphasizing that PLWHA do not have to surrender to the deadly narrative of the disease. It became evident that stigma, both internal and external, largely influences illness narratives. Furthermore, the study revealed the social reconstruction of life narratives both in order to understand the illness in terms of past social experiences and to reaffirm the impression that life has a course and the self has a purpose. All participants found that accessing treatment from the Rhodes University Health Care Centre positively influenced their experiences of adherence and reconstruction of narratives. The study indicates that HIV-related interventions in place at the university need to pay more attention to the psychosocial needs of PLWH, involvement of PWLH, as well as keeping up with the continuously changing global HIV narrative. The study argues for more attention to in-depth experiences and personal narratives in HIV and AIDS, and PLWHA education at Rhodes University. , Thesis (PhD) -- Humanities, Department of Sociology, 2021
- Full Text:
- Date Issued: 2021-04
Effects of organic and inorganic pollutants on the quality of river water and evaluation of possible negative effects on human health in the Eastern Cape Province
- Authors: Vumazonke, Sesethu
- Date: 2020-04
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc (Pharmacy)
- Identifier: http://hdl.handle.net/10962/164727 , vital:41158
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020-04
- Authors: Vumazonke, Sesethu
- Date: 2020-04
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc (Pharmacy)
- Identifier: http://hdl.handle.net/10962/164727 , vital:41158
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020-04
Characterization of the diversity and metabolic potential of hypolithic communities in dronning Maud Land, Antarctica
- Authors: Mikhari, Rito Leanah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178490 , vital:42944
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mikhari, Rito Leanah
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178490 , vital:42944
- Description: Access restricted until April 2022. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
Constraining the role of carbonate assimilation on spinel stability in oxide ores of the Flatreef, Bushveld Complex, South Africa
- Authors: Dyan, Siyasanga
- Date: 2021-04
- Subjects: Oxide minerals -- South Africa -- Bushveld Complex , Transvaal Supergroup (South Africa) , Magmas -- South Africa -- Bushveld Complex , Petrogenesis -- South Africa -- Bushveld Complex , Spinel group – South Africa -- South Africa -- Bushveld Complex , Dolomite -- South Africa -- Bushveld Complex
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174578 , vital:42490
- Description: The northern limb of the Bushveld Complex shows significant evidence for footwall rock- magma interaction, as a result of the emplacement of magmas onto the Transvaal Supergroup sediments. The Platreef of the northern limb is known to have involved extensive contamination of the magma. The lateral extension of the Platreef, the Flatreef, is less contaminated and comprises PGE-mineralization and thick chromitite layers. This enables successful stratigraphic correlation to the Upper Critical Zone of the eastern and western limbs of the Bushveld Complex. This study aims at addressing the influence of dolomitic floor rock contamination on the formation of spinels of the Flatreef and how they may differ to their occurrences in the Bushveld Complex elsewhere. Three main drill cores (UMT-345, UMT-335, and UMT-094) from the deep drilling program by Ivanhoe Mine, north of Turfspruit, were logged and sampled. The drill cores contained rocks contaminated by dolomite in varying degrees, depending on the proportion of carbonate xenoliths present. A total of sixty-two samples were obtained from the UG-2- equivalent chromitite seam, down into the hybrid contaminated units (Footwall Assimilation Zone; FAZ). Petrographic examination of the drill cores revealed that the feldspathic pyroxenite and chromitite layers are the most pristine lithologies in the Flatreef. The chromitite layers occur as a semi-massive to massive ores. The FAZ rocks are mainly dominated by the abundance of Al-rich Cr-spinels (Mg#30-80), clinopyroxenes with a high Ca-Tschermak component (up to 35 mol.%), olivines (Fo72-84), and plagioclase (An31-78). Geochemical characteristics of the feldspathic pyroxenite and chromitite seams include low CaO/Al2O3 and Ca/SiO2 ratios, the low abundance of REE and HFSE. In contrast, the FAZ samples display high CaO/Al2O3 and CaO/SiO2 ratios, suggesting mobilization of CaO-rich fluids derived from the associated dolomite xenoliths. Observations from lithostratigraphic element profiles indicate spikes in CaO within FAZ units relative to the feldspathic pyroxene, indicating a secondary source of CaO linked to proximity to carbonate xenoliths intersected in the core. The assimilation-fractional crystallization model performed with the Upper Critical Zone parental melt and dolomite produced assemblages dominated by spinel, olivine, clinopyroxene, and plagioclase, relating to those of the most contaminated rocks of footwall assimilation zones. The model also showed that large quantities of CO2 were produced during assimilation. High amounts of CO2-fluids mobilized in the melt would have interacted with the melt and increased the overall oxidation conditions. Oxygen fugacity (ƒO2) values were constrained from the spinels in the FAZ and chromites in chromitite seams. Spinels within the most contaminated rocks of the FAZ recorded relatively high ƒO2 values ranging between NNO-0.2 and NNO+1.8 (relative to the Nickel-Nickel-Oxide buffer. High ƒO2 values in spinels from the FAZ suggest that the melt interacted with greater amounts of oxidative CO2-fluids during decarbonation reactions. Such high redox conditions could have triggered the saturation and crystallization of spinels. Comparison of mineral compositions and ƒO2 of UG-2 chromites from the Flatreef with UG-2 from the eastern limb, western limb, chromitites from the Platreef and Uitkomst Complex reveal that Flatreef chromites are of most similar to those of the Platreef Uitkosmt Complex. The northern limb and Uitkomst Complex chromites have high ƒO2 values (NNO+0.3 to NNO+1.2), indicating their apparent link to the Malmani dolomite. Interaction of magma with the Malmani dolomite would have produced high quantities of CO2, triggering an increase in oxidizing conditions. Such an effect is most prominent in the Flatreef chromitites that are in contact with the FAZ. The chromites are characterised by high ƒO2 (NNO+1.2) and distinct compositions (low Cr2O3, high Fe3+/Fetotal, and TiO2). Thus, it is proposed that carbonate assimilation in the Flatreef triggered the precipitation of these distinctive chromites proximal to FAZ, due to liberation of substantial amounts of CO2-rich fluids with a highly oxidative capacity. Carbonate assimilation in layered intrusions can be used as a monitor potential precipitation of chromites. , Thesis (MSc)--Rhodes University, Faculty of Science, Department of Geology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Dyan, Siyasanga
- Date: 2021-04
- Subjects: Oxide minerals -- South Africa -- Bushveld Complex , Transvaal Supergroup (South Africa) , Magmas -- South Africa -- Bushveld Complex , Petrogenesis -- South Africa -- Bushveld Complex , Spinel group – South Africa -- South Africa -- Bushveld Complex , Dolomite -- South Africa -- Bushveld Complex
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174578 , vital:42490
- Description: The northern limb of the Bushveld Complex shows significant evidence for footwall rock- magma interaction, as a result of the emplacement of magmas onto the Transvaal Supergroup sediments. The Platreef of the northern limb is known to have involved extensive contamination of the magma. The lateral extension of the Platreef, the Flatreef, is less contaminated and comprises PGE-mineralization and thick chromitite layers. This enables successful stratigraphic correlation to the Upper Critical Zone of the eastern and western limbs of the Bushveld Complex. This study aims at addressing the influence of dolomitic floor rock contamination on the formation of spinels of the Flatreef and how they may differ to their occurrences in the Bushveld Complex elsewhere. Three main drill cores (UMT-345, UMT-335, and UMT-094) from the deep drilling program by Ivanhoe Mine, north of Turfspruit, were logged and sampled. The drill cores contained rocks contaminated by dolomite in varying degrees, depending on the proportion of carbonate xenoliths present. A total of sixty-two samples were obtained from the UG-2- equivalent chromitite seam, down into the hybrid contaminated units (Footwall Assimilation Zone; FAZ). Petrographic examination of the drill cores revealed that the feldspathic pyroxenite and chromitite layers are the most pristine lithologies in the Flatreef. The chromitite layers occur as a semi-massive to massive ores. The FAZ rocks are mainly dominated by the abundance of Al-rich Cr-spinels (Mg#30-80), clinopyroxenes with a high Ca-Tschermak component (up to 35 mol.%), olivines (Fo72-84), and plagioclase (An31-78). Geochemical characteristics of the feldspathic pyroxenite and chromitite seams include low CaO/Al2O3 and Ca/SiO2 ratios, the low abundance of REE and HFSE. In contrast, the FAZ samples display high CaO/Al2O3 and CaO/SiO2 ratios, suggesting mobilization of CaO-rich fluids derived from the associated dolomite xenoliths. Observations from lithostratigraphic element profiles indicate spikes in CaO within FAZ units relative to the feldspathic pyroxene, indicating a secondary source of CaO linked to proximity to carbonate xenoliths intersected in the core. The assimilation-fractional crystallization model performed with the Upper Critical Zone parental melt and dolomite produced assemblages dominated by spinel, olivine, clinopyroxene, and plagioclase, relating to those of the most contaminated rocks of footwall assimilation zones. The model also showed that large quantities of CO2 were produced during assimilation. High amounts of CO2-fluids mobilized in the melt would have interacted with the melt and increased the overall oxidation conditions. Oxygen fugacity (ƒO2) values were constrained from the spinels in the FAZ and chromites in chromitite seams. Spinels within the most contaminated rocks of the FAZ recorded relatively high ƒO2 values ranging between NNO-0.2 and NNO+1.8 (relative to the Nickel-Nickel-Oxide buffer. High ƒO2 values in spinels from the FAZ suggest that the melt interacted with greater amounts of oxidative CO2-fluids during decarbonation reactions. Such high redox conditions could have triggered the saturation and crystallization of spinels. Comparison of mineral compositions and ƒO2 of UG-2 chromites from the Flatreef with UG-2 from the eastern limb, western limb, chromitites from the Platreef and Uitkomst Complex reveal that Flatreef chromites are of most similar to those of the Platreef Uitkosmt Complex. The northern limb and Uitkomst Complex chromites have high ƒO2 values (NNO+0.3 to NNO+1.2), indicating their apparent link to the Malmani dolomite. Interaction of magma with the Malmani dolomite would have produced high quantities of CO2, triggering an increase in oxidizing conditions. Such an effect is most prominent in the Flatreef chromitites that are in contact with the FAZ. The chromites are characterised by high ƒO2 (NNO+1.2) and distinct compositions (low Cr2O3, high Fe3+/Fetotal, and TiO2). Thus, it is proposed that carbonate assimilation in the Flatreef triggered the precipitation of these distinctive chromites proximal to FAZ, due to liberation of substantial amounts of CO2-rich fluids with a highly oxidative capacity. Carbonate assimilation in layered intrusions can be used as a monitor potential precipitation of chromites. , Thesis (MSc)--Rhodes University, Faculty of Science, Department of Geology, 2021
- Full Text:
- Date Issued: 2021-04
Development and characterisation of ciprofloxacin hydrochloride solid lipid nanoparticles for ocular delivery
- Authors: Dhege, Clarence
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178446 , vital:42940
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Dhege, Clarence
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178446 , vital:42940
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Indigenous knowledge of ecosystem services in rural communities of the Eastern Cape, South Africa
- Authors: Murata, Chenai
- Date: 2021-04
- Subjects: Ethnoscience -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Nature -- Effect of human beings on -- South Africa -- Eastern Cape , Human ecology -- South Africa -- Eastern Cape , Human beings -- Effect of environment on -- South Africa -- Eastern Cape , South Africa -- Eastern Cape -- Rural conditions
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177929 , vital:42891 , 10.21504/10962/177929
- Description: This thesis is on indigenous knowledge of ecosystem services. The ecosystem service framework and its associated concepts are fairly young, having been introduced in the ecological discipline in the 1980s. The ecosystem service framework posits that the wellbeing of humans and their communities is dependent on services supplied by ecosystems. It emphasises that for the ecosystems to be able to supply the services, they need to be in a well-functioning state. This idea of well-functioning is predicated on the argument that the ecosystem service framework enjoins resource users to exercise responsible stewardship to prevent degradation and overharvesting. Moreover, the concept of dependence suggests that ecosystem services are of value to humans. The dominant means of measuring the value of ecosystem services has been the economic valuation method in which the contribution that each service makes to human wellbeing is quantified into monetary units. The framework disaggregates the services into four groups, namely provisioning, cultural, supporting and regulatory and seeks to all the pillars of human wellbeing including health, subsistence and spirituality into each of these groups. In doing all this, the framework significantly reconfigures the way we look at and present human-nature relations. This change has the potential to influence significant shifts in how ecological research and intervention programmes are conducted in the foreseeable future. However, the reality that the ecosystem service framework was formulated within, and is informed by the scientific epistemology begs the question: what do traditional rural communities who depend mainly on indigenous knowledge systems (IKS) for shaping and interoperating their relations with nature know of the ecosystem service concept? Rural communities are the ones who interact directly with nature on a day-to-day basis. This makes them a very critical component in the ecosystem service framework. Although South Africa has had studies in the ecosystem service theme, little has been done to attempt to investigate and document indigenous knowledge of ecosystem services that rural communities possess. By focusing only on scientific knowledge of ecosystem services, the South African literature does not do justice to the plural epistemologies of the ecosystem service users in the country. More importantly, the continued dearth of public information on indigenous knowledge of ecosystem services can potentially obstruct implementation of locally sensitive intervention programmes because nothing is known about how the local communities conceptualise the ecosystem service framework. All this presents a crucial gap in the South African research; one that unless effort is made to contribute towards filling it, our knowledge of how communities experience the ecosystem service framework in South Africa will remain skewed. This study set out to investigate and document indigenous knowledge of ecosystem services in order to contribute towards filling this gap. Indigenous knowledge system is an umbrella epistemic system that includes lay ecological knowledge (LEK), traditional ecological knowledge (TEK) and many other related organized systems of knowing. Although the thesis has a chapter on LEK, its primary focus was TEK because the thesis was interested in unravelling how aspects of tradition including taboos, customs, traditional rules and belief in ancestral forces influence local communities’ knowledge of some key aspects of the ecosystem service framework including knowledge of various ecosystem services, valuation of ecosystem services, management of ecosystem services and perceptions of the management practices. The decision to focus on TEK was based on the reasoning that rural communities of the Eastern Cape boast a strong reputation of being traditional, recognizing ancestral spirits, legends and taboos as critical tools of knowledge generation and transmission. Using both mixed methods in some chapters and the qualitative approach alone in others, the study collected data in five villages of Mgwalana, Mahlungulu, Colana, Gogela and Nozitshena located in the north eastern part of Eastern Cape Province of South Africa, a region formerly called Transkei. The data were collected not on ecosystem services; but on the local people’s knowledge of ecosystem services. Although literature was consulted, the study regarded respondents as the primary source of data, hence the findings and conclusions presented in this thesis are about what local people know about ecosystem services. The study uses critical realist theoretical lenses to interpret respondents’ reports. The lenses included the principle of the separation between ontology and epistemology, the iceberg metaphor of ontology, epistemological pluralism and the hermeneutic dimension. These lenses were used to make sense of both the knowledge system of local people and the things about which their knowledge was. As part of discussing the local people’s knowledge, the study sometimes refers to science. This is not because I expected them to demonstrate knowledge similar to science. Instead, it was a critical realist dialectical way of explaining what something is by demonstrating what it is not. The study made a couple of key findings that can potentially enhance the growth of the South African ecosystem service discipline. First, respondents demonstrated knowledge of ecosystem services by mentioning a range of them such as drinking water, medicinal plants, cultural plants and fuelwood and how they affect the wellbeing of humans. However, what they did not have good knowledge of is that nature services can be classified into the four groups of supporting, regulatory, cultural and provisioning. Among the four ecosystem services groups, respondents could identify two only; provisional and cultural. Second, local communities depend heavily on ecosystem services for their well-being. The services include fuelwood, construction timber, medicinal plants, wild fruits, wild fish, cultural services and thatch grass. Although they appreciate that ecosystem services have value to their wellbeing, local people found it difficult to represent the value in monetary units. The conditions that make it difficult for local people to perceive ecosystem services as commodities include the absence of well-defined property system, lack of a quantitative consumer tradition and absence of an economic conception of nature. Third, local people understand the need to keep ecosystems in a well-functioning state hence they implement several traditional practices to manage ecosystem services. These practices include taboos, designating certain resources as sacred, legends, customary law, as well as some secular practices including gelesha and stone terracing. However, it is not easy to understand how traditional management practices work because they are not empirically observable. Fourth, local people possess knowledge of the reality that if not well managed, ecosystems can undergo degradation and hence fail to supply the services needed for human wellbeing. However, they explain the causes of degradation in terms of changes observable at the empirical level and the invisible causal power of supernatural forces. The inclusion of natural forces in degradation explanations marks a departure from the scientific explanations that revolve around biophysical processes. Fifth, the use of traditional management practices such as taboos to management ecosystems is under threat at the local communities. The threat can be attributed to three groups of causes, namely changes in worldviews due to adoption of formal education and Christianity, institutional disharmony playing out between the state and local traditional leadership, and lifestyle changes. These challenges constrain the opportunity for local people to apply traditional management practices to prevent the degradation of ecosystems. The net implication of this is that it renders it difficult for researchers and policy makers to assess the effectiveness of traditional management practices because they are not being implemented in full. In light of all these findings, the thesis concludes that TEK is underlabouring for the ecosystem service framework in the sense that it is used by local communities to generate knowledge of ecological concepts and phenomena. This means that TEK does not exist for the sake of its own self. Drawing from this finding, the study proposes a framework of analysing TEK as an underlabourer for social-ecological triggers or issues. Nonetheless, there are few factors that can be sources of limitation to the study. These include the reality that it was difficult to access pure traditional knowledge because over the years the local communities have received many state-sponsored ecological intervention programmes and a possible personal bias given the reality that I grew up in a traditional household and my father was a key holder or TEK. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021 , Thesis chapter to be published in 'Green and Low-Carbon Economy'. Journal available: https://ojs.bonviewpress.com/index.php/GLCE/index
- Full Text:
- Date Issued: 2021-04
- Authors: Murata, Chenai
- Date: 2021-04
- Subjects: Ethnoscience -- South Africa -- Eastern Cape , Ecosystem management -- South Africa -- Eastern Cape , Nature -- Effect of human beings on -- South Africa -- Eastern Cape , Human ecology -- South Africa -- Eastern Cape , Human beings -- Effect of environment on -- South Africa -- Eastern Cape , South Africa -- Eastern Cape -- Rural conditions
- Language: English
- Type: thesis , text , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/177929 , vital:42891 , 10.21504/10962/177929
- Description: This thesis is on indigenous knowledge of ecosystem services. The ecosystem service framework and its associated concepts are fairly young, having been introduced in the ecological discipline in the 1980s. The ecosystem service framework posits that the wellbeing of humans and their communities is dependent on services supplied by ecosystems. It emphasises that for the ecosystems to be able to supply the services, they need to be in a well-functioning state. This idea of well-functioning is predicated on the argument that the ecosystem service framework enjoins resource users to exercise responsible stewardship to prevent degradation and overharvesting. Moreover, the concept of dependence suggests that ecosystem services are of value to humans. The dominant means of measuring the value of ecosystem services has been the economic valuation method in which the contribution that each service makes to human wellbeing is quantified into monetary units. The framework disaggregates the services into four groups, namely provisioning, cultural, supporting and regulatory and seeks to all the pillars of human wellbeing including health, subsistence and spirituality into each of these groups. In doing all this, the framework significantly reconfigures the way we look at and present human-nature relations. This change has the potential to influence significant shifts in how ecological research and intervention programmes are conducted in the foreseeable future. However, the reality that the ecosystem service framework was formulated within, and is informed by the scientific epistemology begs the question: what do traditional rural communities who depend mainly on indigenous knowledge systems (IKS) for shaping and interoperating their relations with nature know of the ecosystem service concept? Rural communities are the ones who interact directly with nature on a day-to-day basis. This makes them a very critical component in the ecosystem service framework. Although South Africa has had studies in the ecosystem service theme, little has been done to attempt to investigate and document indigenous knowledge of ecosystem services that rural communities possess. By focusing only on scientific knowledge of ecosystem services, the South African literature does not do justice to the plural epistemologies of the ecosystem service users in the country. More importantly, the continued dearth of public information on indigenous knowledge of ecosystem services can potentially obstruct implementation of locally sensitive intervention programmes because nothing is known about how the local communities conceptualise the ecosystem service framework. All this presents a crucial gap in the South African research; one that unless effort is made to contribute towards filling it, our knowledge of how communities experience the ecosystem service framework in South Africa will remain skewed. This study set out to investigate and document indigenous knowledge of ecosystem services in order to contribute towards filling this gap. Indigenous knowledge system is an umbrella epistemic system that includes lay ecological knowledge (LEK), traditional ecological knowledge (TEK) and many other related organized systems of knowing. Although the thesis has a chapter on LEK, its primary focus was TEK because the thesis was interested in unravelling how aspects of tradition including taboos, customs, traditional rules and belief in ancestral forces influence local communities’ knowledge of some key aspects of the ecosystem service framework including knowledge of various ecosystem services, valuation of ecosystem services, management of ecosystem services and perceptions of the management practices. The decision to focus on TEK was based on the reasoning that rural communities of the Eastern Cape boast a strong reputation of being traditional, recognizing ancestral spirits, legends and taboos as critical tools of knowledge generation and transmission. Using both mixed methods in some chapters and the qualitative approach alone in others, the study collected data in five villages of Mgwalana, Mahlungulu, Colana, Gogela and Nozitshena located in the north eastern part of Eastern Cape Province of South Africa, a region formerly called Transkei. The data were collected not on ecosystem services; but on the local people’s knowledge of ecosystem services. Although literature was consulted, the study regarded respondents as the primary source of data, hence the findings and conclusions presented in this thesis are about what local people know about ecosystem services. The study uses critical realist theoretical lenses to interpret respondents’ reports. The lenses included the principle of the separation between ontology and epistemology, the iceberg metaphor of ontology, epistemological pluralism and the hermeneutic dimension. These lenses were used to make sense of both the knowledge system of local people and the things about which their knowledge was. As part of discussing the local people’s knowledge, the study sometimes refers to science. This is not because I expected them to demonstrate knowledge similar to science. Instead, it was a critical realist dialectical way of explaining what something is by demonstrating what it is not. The study made a couple of key findings that can potentially enhance the growth of the South African ecosystem service discipline. First, respondents demonstrated knowledge of ecosystem services by mentioning a range of them such as drinking water, medicinal plants, cultural plants and fuelwood and how they affect the wellbeing of humans. However, what they did not have good knowledge of is that nature services can be classified into the four groups of supporting, regulatory, cultural and provisioning. Among the four ecosystem services groups, respondents could identify two only; provisional and cultural. Second, local communities depend heavily on ecosystem services for their well-being. The services include fuelwood, construction timber, medicinal plants, wild fruits, wild fish, cultural services and thatch grass. Although they appreciate that ecosystem services have value to their wellbeing, local people found it difficult to represent the value in monetary units. The conditions that make it difficult for local people to perceive ecosystem services as commodities include the absence of well-defined property system, lack of a quantitative consumer tradition and absence of an economic conception of nature. Third, local people understand the need to keep ecosystems in a well-functioning state hence they implement several traditional practices to manage ecosystem services. These practices include taboos, designating certain resources as sacred, legends, customary law, as well as some secular practices including gelesha and stone terracing. However, it is not easy to understand how traditional management practices work because they are not empirically observable. Fourth, local people possess knowledge of the reality that if not well managed, ecosystems can undergo degradation and hence fail to supply the services needed for human wellbeing. However, they explain the causes of degradation in terms of changes observable at the empirical level and the invisible causal power of supernatural forces. The inclusion of natural forces in degradation explanations marks a departure from the scientific explanations that revolve around biophysical processes. Fifth, the use of traditional management practices such as taboos to management ecosystems is under threat at the local communities. The threat can be attributed to three groups of causes, namely changes in worldviews due to adoption of formal education and Christianity, institutional disharmony playing out between the state and local traditional leadership, and lifestyle changes. These challenges constrain the opportunity for local people to apply traditional management practices to prevent the degradation of ecosystems. The net implication of this is that it renders it difficult for researchers and policy makers to assess the effectiveness of traditional management practices because they are not being implemented in full. In light of all these findings, the thesis concludes that TEK is underlabouring for the ecosystem service framework in the sense that it is used by local communities to generate knowledge of ecological concepts and phenomena. This means that TEK does not exist for the sake of its own self. Drawing from this finding, the study proposes a framework of analysing TEK as an underlabourer for social-ecological triggers or issues. Nonetheless, there are few factors that can be sources of limitation to the study. These include the reality that it was difficult to access pure traditional knowledge because over the years the local communities have received many state-sponsored ecological intervention programmes and a possible personal bias given the reality that I grew up in a traditional household and my father was a key holder or TEK. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021 , Thesis chapter to be published in 'Green and Low-Carbon Economy'. Journal available: https://ojs.bonviewpress.com/index.php/GLCE/index
- Full Text:
- Date Issued: 2021-04
Motivation to learn science and make sense of the concept of malleability through the traditional blast furnace in a grade 9 Physical Science class
- Authors: Kudumo, Wilfred Peter
- Date: 2021-04
- Subjects: Science -- Study and teaching (Secondary) -- Namibia -- Kavango West , Metals -- Effect of high temperatures on , Blast furnaces , Ethnoscience -- Namibia -- Kavango West , Ubuntu (Philosophy) , Culturally relevant pedagogy , Motivation in education -- Namibia -- Kavango West , Continuity Argumentative Theory (CAT)
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177262 , vital:42804
- Description: The current situation of teaching and learning science in Namibia is of great concern since it does not seem to take into consideration learners’ socio-cultural backgrounds. As a result, learners are finding that science is not relevant to their everyday life experiences and hence are not motivated to learn it. This is compounded in part by the fact that the Namibian curriculum seems to be silent on how science teachers should include learners’ socio-cultural backgrounds, for example, local or indigenous knowledge in their teaching repertoires. It is against this background that in this study I explored how mobilising the cultural practice of a traditional blast furnace (mudukuto) as an approach enables and/or constrains learners’ motivation to learn science and make sense of the concept of malleability. This is a qualitative case study underpinned by a combination of interpretive and Ubuntu paradigms. It was carried out in a rural school in Namibia, Kavango West Region, where I am currently teaching. The participants in the study were grade 9 learners and one expert community member. Focus group interviews, participatory observation, learners’ reflections, and stimulated recall interviews were used to gather qualitative data. Vygotsky’s socio-cultural theory was used as a theoretical framework and Ogunniyi`s Continuity Argumentative Theory (CAT) was used as analytical framework or lens to analyse the data. A thematic approach to analyse data was employed. That is, qualitative data were analysed inductively to come up with sub-themes and themes. The findings of the study revealed that the traditional furnace motivated the learners involved in this study to learn science and learners were able to extract science concepts on malleability from the traditional practice. The implication for this study is that when science is related to learners’ daily life or real-world experiences, they are enabled to bridge the gap from what they learn at home or in the community with school science. The study thus recommends that teachers should make an effort to integrate local or indigenous knowledge and practices to make science accessible and relevant in their classrooms. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Kudumo, Wilfred Peter
- Date: 2021-04
- Subjects: Science -- Study and teaching (Secondary) -- Namibia -- Kavango West , Metals -- Effect of high temperatures on , Blast furnaces , Ethnoscience -- Namibia -- Kavango West , Ubuntu (Philosophy) , Culturally relevant pedagogy , Motivation in education -- Namibia -- Kavango West , Continuity Argumentative Theory (CAT)
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177262 , vital:42804
- Description: The current situation of teaching and learning science in Namibia is of great concern since it does not seem to take into consideration learners’ socio-cultural backgrounds. As a result, learners are finding that science is not relevant to their everyday life experiences and hence are not motivated to learn it. This is compounded in part by the fact that the Namibian curriculum seems to be silent on how science teachers should include learners’ socio-cultural backgrounds, for example, local or indigenous knowledge in their teaching repertoires. It is against this background that in this study I explored how mobilising the cultural practice of a traditional blast furnace (mudukuto) as an approach enables and/or constrains learners’ motivation to learn science and make sense of the concept of malleability. This is a qualitative case study underpinned by a combination of interpretive and Ubuntu paradigms. It was carried out in a rural school in Namibia, Kavango West Region, where I am currently teaching. The participants in the study were grade 9 learners and one expert community member. Focus group interviews, participatory observation, learners’ reflections, and stimulated recall interviews were used to gather qualitative data. Vygotsky’s socio-cultural theory was used as a theoretical framework and Ogunniyi`s Continuity Argumentative Theory (CAT) was used as analytical framework or lens to analyse the data. A thematic approach to analyse data was employed. That is, qualitative data were analysed inductively to come up with sub-themes and themes. The findings of the study revealed that the traditional furnace motivated the learners involved in this study to learn science and learners were able to extract science concepts on malleability from the traditional practice. The implication for this study is that when science is related to learners’ daily life or real-world experiences, they are enabled to bridge the gap from what they learn at home or in the community with school science. The study thus recommends that teachers should make an effort to integrate local or indigenous knowledge and practices to make science accessible and relevant in their classrooms. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
Development and assessment of rifampicin loaded self-microemulsifying drug delivery systems
- Authors: Mphaphuli, Mashudu Theodore
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178503 , vital:42945
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mphaphuli, Mashudu Theodore
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178503 , vital:42945
- Description: Access restricted until April 2023. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Volatility spillovers and determinants of contagion: a case of BRICS equity and foreign exchange markets
- Authors: Nyopa, Tšepiso
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MCOM
- Identifier: http://hdl.handle.net/10962/164590 , vital:41146
- Description: Thesis (MSc)--Rhodes University, Faculty of Commerce, Economics and Economic History, 2020
- Full Text:
- Date Issued: 2020
- Authors: Nyopa, Tšepiso
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MCOM
- Identifier: http://hdl.handle.net/10962/164590 , vital:41146
- Description: Thesis (MSc)--Rhodes University, Faculty of Commerce, Economics and Economic History, 2020
- Full Text:
- Date Issued: 2020