Potential impact and host range of Pereskiophaga brasiliensis Anderson (Curculionidae): a new candidate biological control agent for the control of Pereskia aculeata Miller (Cactaceae) in South Africa
- Authors: Mdodana, Lumka Anita
- Date: 2018
- Subjects: Curculionidae -- South Africa , Cactus -- South Africa , Biological pest control agents , Alien plants-- South Africa , Pereskiophaga brasiliensis Anderson (Curculionidae) , Pereskia aculeata Miller (Cactaceae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62350 , vital:28157
- Description: Pereskia aculeata Miller (Cactaceae) is a damaging invasive alien plant in South Africa that has negative impacts to indigenous biodiversity and ecosystem functioning. Mechanical and chemical control are not effective against P. aculeata so biological control is considered the only viable option. Two biological control agents, the leaf-feeding beetle Phenrica guerini Bechyne (Chrysomelidae) and the stem-wilting bug Catorhintha schaffneri (Coreidae), have been released in South Africa thus far. Post-release evaluations have indicated that P. guerini will not reduce P. aculeata densities to acceptable levels alone, while C. schaffneri was released very recently, so it is too soon to determine how effective that agent will be. Even if C. schaffneri is extremely damaging, it is likely that further agents will be required to reduce the densities of P. aculeata to acceptable levels within a reasonable time-scale. Additional agents should target the woody stems of P. aculeata which are not impacted by the damage of either of the released agents. Pereskiophaga brasiliensis Anderson (Curculionidae) is a promising potential candidate agent that feeds on the thick woody stems of the plant in the larval stage. Climatic matching, genetic matching and field based host specificity observations all indicated that P. brasiliensis was a promising candidate. In this study, the impact of P. brasiliensis to the target weed, P. aculeata, was quantified under quarantine conditions to determine whether it was sufficiently damaging to warrant release. This was followed by host specificity testing to determine whether P. brasiliensis was suitably host specific for release in South Africa. Impact studies indicated that P. brasiliensis was damaging to P. aculeata at insect densities that would be expected in the field. Pereskiophaga brasiliensis reduced the number of leaves of P. aculeata to a greater extent than it reduced shoot lengths, but both plant parameters were significantly reduced due to the feeding damage from the insect. This suggests that the damage from P. brasiliensis may be compatible with that of C. schaffneri which reduces shoot length to a greater degree than the number of leaves. Pereskiophaga brasiliensis is therefore sufficiently damaging to warrant release, and although interaction studies with the other agents would be required, it is expected that it should complement other existing agents. Although P. brasiliensis is sufficiently damaging, at present the host specificity data indicates that it is not suitably specific for release in South Africa because oviposition and larval development to the adult stage was recorded on both indigenous and alien plant species within the families Cactaceae and Basellaceae. This non-target feeding was recorded during no-choice tests, which are very conservative, but significant non-target damage and development to the adult stage was recorded on an indigenous plant from a different family to the target weed. Further host specificity testing, including paired and multiple choice tests, are required to confirm the broad host range of P. brasiliensis. Other biological control agents that damage the woody stems of P. aculeata should be considered. The stem-borer, Acanthodoxus machacalis (Cerambycidae) is considered the most promising of the other candidate agents as it can be sourced from a climatically matched region where genetically suitable P. aculeata plants are found, it is sufficiently damaging to the woody stems of P. aculeata and there is no evidence that the species has a broad host range. Acanthodoxus machacalis should be sourced from Rio de Janeiro, Brazil, and imported into quarantine in South Africa for host specificity testing.
- Full Text:
- Date Issued: 2018
- Authors: Mdodana, Lumka Anita
- Date: 2018
- Subjects: Curculionidae -- South Africa , Cactus -- South Africa , Biological pest control agents , Alien plants-- South Africa , Pereskiophaga brasiliensis Anderson (Curculionidae) , Pereskia aculeata Miller (Cactaceae)
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62350 , vital:28157
- Description: Pereskia aculeata Miller (Cactaceae) is a damaging invasive alien plant in South Africa that has negative impacts to indigenous biodiversity and ecosystem functioning. Mechanical and chemical control are not effective against P. aculeata so biological control is considered the only viable option. Two biological control agents, the leaf-feeding beetle Phenrica guerini Bechyne (Chrysomelidae) and the stem-wilting bug Catorhintha schaffneri (Coreidae), have been released in South Africa thus far. Post-release evaluations have indicated that P. guerini will not reduce P. aculeata densities to acceptable levels alone, while C. schaffneri was released very recently, so it is too soon to determine how effective that agent will be. Even if C. schaffneri is extremely damaging, it is likely that further agents will be required to reduce the densities of P. aculeata to acceptable levels within a reasonable time-scale. Additional agents should target the woody stems of P. aculeata which are not impacted by the damage of either of the released agents. Pereskiophaga brasiliensis Anderson (Curculionidae) is a promising potential candidate agent that feeds on the thick woody stems of the plant in the larval stage. Climatic matching, genetic matching and field based host specificity observations all indicated that P. brasiliensis was a promising candidate. In this study, the impact of P. brasiliensis to the target weed, P. aculeata, was quantified under quarantine conditions to determine whether it was sufficiently damaging to warrant release. This was followed by host specificity testing to determine whether P. brasiliensis was suitably host specific for release in South Africa. Impact studies indicated that P. brasiliensis was damaging to P. aculeata at insect densities that would be expected in the field. Pereskiophaga brasiliensis reduced the number of leaves of P. aculeata to a greater extent than it reduced shoot lengths, but both plant parameters were significantly reduced due to the feeding damage from the insect. This suggests that the damage from P. brasiliensis may be compatible with that of C. schaffneri which reduces shoot length to a greater degree than the number of leaves. Pereskiophaga brasiliensis is therefore sufficiently damaging to warrant release, and although interaction studies with the other agents would be required, it is expected that it should complement other existing agents. Although P. brasiliensis is sufficiently damaging, at present the host specificity data indicates that it is not suitably specific for release in South Africa because oviposition and larval development to the adult stage was recorded on both indigenous and alien plant species within the families Cactaceae and Basellaceae. This non-target feeding was recorded during no-choice tests, which are very conservative, but significant non-target damage and development to the adult stage was recorded on an indigenous plant from a different family to the target weed. Further host specificity testing, including paired and multiple choice tests, are required to confirm the broad host range of P. brasiliensis. Other biological control agents that damage the woody stems of P. aculeata should be considered. The stem-borer, Acanthodoxus machacalis (Cerambycidae) is considered the most promising of the other candidate agents as it can be sourced from a climatically matched region where genetically suitable P. aculeata plants are found, it is sufficiently damaging to the woody stems of P. aculeata and there is no evidence that the species has a broad host range. Acanthodoxus machacalis should be sourced from Rio de Janeiro, Brazil, and imported into quarantine in South Africa for host specificity testing.
- Full Text:
- Date Issued: 2018
A medicinal chemistry study in nitrogen containing heterocycles
- Authors: Lunga, Mayibongwe Junior
- Date: 2018
- Subjects: Indole , Tetrazoles , Antimalarials , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/63521 , vital:28430
- Description: Heterocyclic structures have found extensive utility in the field of medicinal chemistry, as prominent regions of pharmacophores resulting in numerous drug treatments for many diseases. Accordingly, in this project we explored the respective antimalarial and anticancer activity exhibited by compounds featuring nitrogen containing indole and tetrazole heterocycles respectively. This thesis therefore comprises of two distinct parts. Part 1. Following the development of resistance towards traditional antimalarial therapy such as chloroquine and emerging resistance towards artemisinin combination therapies, the WHO reported the urgent need for new, effective drugs and identification of new drug targets to combat the Plasmodium falciparum parasite. In 2015 the parasite was the cause of 429 000 deaths, the majority occurring in the sub-Saharan region of Africa. This highlights the failing effectiveness of vector control strategies, reiterating the need to develop alternative control and treatment strategies. In response to this need we wanted to expand and further describe the SAR of the indole based series, indolyl-3-ethanone-α- thioethers, previously synthesized in our laboratory. These compounds were found to exhibit antimalarial activity with compounds 2.26 and 2.27 exhibiting activity against P. falciparum 3D7 in the nanomolar range. Based on these compounds we synthesized compounds 3.21 and 3.24 – 3.32 following a three step reaction pathway. Our results in this study, indicate that compound 3.28, a pnitrothiophenol analogue of 2.27 was the most active of the compounds we synthesized and furthermore was superior in activity against Plasmodium compared to 2.27. This result indicated that the presence of p-NO2 is important in enhancing anti-plasmodial activity. Comparing compounds 3.25 and 3.26 with an oxygen on the ether bridge to compounds 3.29 and 3.30 with a sulfur, we observed an increase in hydrophilicity coupled to a decrease in anti-plasmodial activity in the compounds, thus, highlighting the importance of sulfur for enhanced activity. Furthermore, we investigated bioisosteric replacement of the 5-chloro substituent present in hit compounds 2.27 and 3.28, with an electron withdrawing nitrile (3.27) and electron donating methyl (3.29) and methoxy (3.31) substituents. These substituents decreased anti-plasmodial activity, confirming that a chlorine substituent is optimal for biological activity. This study furthered our understanding of the SAR of indolyl-3-ethanone-α- thioethers for the development of potent anti-plasmodial lead compounds. Part 2. Triple negative breast cancer (TNBC), which disproportionately affects women of sub-Saharan Africa, is unresponsive to hormone-based therapies. This emergence presents a population of patients devoid of effective drug treatment, signaling the urgent need to develop new effective therapies with novel drug targets. Therefore, we identified our target in TNBC cells as the protein-protein interaction between the co-chaperones HOP and HSP90. We reasoned that a disruption of this interaction would ultimately result in cancer cell death via the degradation of essential oncogenic client proteins. Following a fragment screening campaign, which identified several acid and tetrazole containing hits (4.56 – 4.58) which bound to HOP, with low anticancer activity, we sought to develop synthetic methodology to elaborate our fragment hits synthesizing tetrazole containing fragments to target TNBC cell lines. We therefore proceeded to synthesize a range of multi substituted fragments (4.59 – 4.63), utilizing a nitrile (4.66) to access tetrazoles via 1,3-cycloaddition and an acid by nitrile hydrolysis. We successfully synthesized the tetrazole and acid fragments which are currently undergoing characterization for activity against TNBC. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
- Authors: Lunga, Mayibongwe Junior
- Date: 2018
- Subjects: Indole , Tetrazoles , Antimalarials , Heat shock proteins , Plasmodium falciparum
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/63521 , vital:28430
- Description: Heterocyclic structures have found extensive utility in the field of medicinal chemistry, as prominent regions of pharmacophores resulting in numerous drug treatments for many diseases. Accordingly, in this project we explored the respective antimalarial and anticancer activity exhibited by compounds featuring nitrogen containing indole and tetrazole heterocycles respectively. This thesis therefore comprises of two distinct parts. Part 1. Following the development of resistance towards traditional antimalarial therapy such as chloroquine and emerging resistance towards artemisinin combination therapies, the WHO reported the urgent need for new, effective drugs and identification of new drug targets to combat the Plasmodium falciparum parasite. In 2015 the parasite was the cause of 429 000 deaths, the majority occurring in the sub-Saharan region of Africa. This highlights the failing effectiveness of vector control strategies, reiterating the need to develop alternative control and treatment strategies. In response to this need we wanted to expand and further describe the SAR of the indole based series, indolyl-3-ethanone-α- thioethers, previously synthesized in our laboratory. These compounds were found to exhibit antimalarial activity with compounds 2.26 and 2.27 exhibiting activity against P. falciparum 3D7 in the nanomolar range. Based on these compounds we synthesized compounds 3.21 and 3.24 – 3.32 following a three step reaction pathway. Our results in this study, indicate that compound 3.28, a pnitrothiophenol analogue of 2.27 was the most active of the compounds we synthesized and furthermore was superior in activity against Plasmodium compared to 2.27. This result indicated that the presence of p-NO2 is important in enhancing anti-plasmodial activity. Comparing compounds 3.25 and 3.26 with an oxygen on the ether bridge to compounds 3.29 and 3.30 with a sulfur, we observed an increase in hydrophilicity coupled to a decrease in anti-plasmodial activity in the compounds, thus, highlighting the importance of sulfur for enhanced activity. Furthermore, we investigated bioisosteric replacement of the 5-chloro substituent present in hit compounds 2.27 and 3.28, with an electron withdrawing nitrile (3.27) and electron donating methyl (3.29) and methoxy (3.31) substituents. These substituents decreased anti-plasmodial activity, confirming that a chlorine substituent is optimal for biological activity. This study furthered our understanding of the SAR of indolyl-3-ethanone-α- thioethers for the development of potent anti-plasmodial lead compounds. Part 2. Triple negative breast cancer (TNBC), which disproportionately affects women of sub-Saharan Africa, is unresponsive to hormone-based therapies. This emergence presents a population of patients devoid of effective drug treatment, signaling the urgent need to develop new effective therapies with novel drug targets. Therefore, we identified our target in TNBC cells as the protein-protein interaction between the co-chaperones HOP and HSP90. We reasoned that a disruption of this interaction would ultimately result in cancer cell death via the degradation of essential oncogenic client proteins. Following a fragment screening campaign, which identified several acid and tetrazole containing hits (4.56 – 4.58) which bound to HOP, with low anticancer activity, we sought to develop synthetic methodology to elaborate our fragment hits synthesizing tetrazole containing fragments to target TNBC cell lines. We therefore proceeded to synthesize a range of multi substituted fragments (4.59 – 4.63), utilizing a nitrile (4.66) to access tetrazoles via 1,3-cycloaddition and an acid by nitrile hydrolysis. We successfully synthesized the tetrazole and acid fragments which are currently undergoing characterization for activity against TNBC. , Thesis (MSc) -- Faculty of Pharmacy, Pharmacy, 2018
- Full Text:
- Date Issued: 2018
Exploring the potential of imines as antiprotozoan agents with focus on t. Brucei and p. Falciparum
- Authors: Oluwafemi, Kola Augustus
- Date: 2018
- Subjects: Protozoa , Parasites , Imines , Nuclear magnetic resonance , HeLa cells , Plasmodium falciparum , Trypanosoma brucei , Isomerism
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/62235 , vital:28145 , DOI 10.21504/10962/62235
- Description: This work focuses on the design, synthesis and evaluation of imine-containing heterocyclic and acyclic compounds with special focus on their bioactivity against parasitic protozoans (P. falciparum and T. brucei) - given the context of drug resistance in the treatment of malaria and Human African sleeping sickness and the fact that several bioactive organic compounds have been reported to possess the imino group. Starting from 2-aminopyridine, novel #-alkylated-5-bromo-7-azabenzimidazoles and substituted 5-bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives were prepared, and their bioactivity against parasitic protozoans was assessed. NMR spectra of the substituted 5- bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives exhibited rotational isomerism, and a dynamic NMR study was used in the estimation of the rate constants and the free- energies of activation for rotation. The free-energy differences between the two rotamers were determined and the more stable conformations were predicted. Novel 2-phenyl-7-azabenzimidazoles were also synthesised from 2-aminopyridine. A convenient method for the regioselective formylation of 2,3-diaminopyridines into 2-amino- 7-(benzylimino)pyridine analogues of 2-phenyl-7-azabenzimidazole was developed, and some of the resulting imino derivatives were hydrogenated to verify the importance of the imino moiety for bioactivity. The 2-phenyl-7-azabenzimidazoles and the 2-amino-7- (benzylimino)pyridine analogues were screened for their anti-protozoal activity and their cytotoxicity level was determined against the HeLa cell line. In order to validate the importance of the pyridine moiety, novel #-(phenyl)-2- hydroxybenzylimines, #-(benzyl)-2-hydroxybenzylimines and (±)-trans-1,2-bis[2- hydroxybenzylimino]cyclohexanes were also synthesized and screened for activity against the parasitic protozoans and for cytotoxicity against the HeLa cell line. The biological assay results indicated that these compounds are not significantly cytotoxic and a good number of them show potential as lead compounds for the development of new malaria and trypanosomiasis drugs. , Thesis (PhD) -- Faculty of Science, Chemistry, 2018
- Full Text:
- Date Issued: 2018
- Authors: Oluwafemi, Kola Augustus
- Date: 2018
- Subjects: Protozoa , Parasites , Imines , Nuclear magnetic resonance , HeLa cells , Plasmodium falciparum , Trypanosoma brucei , Isomerism
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/62235 , vital:28145 , DOI 10.21504/10962/62235
- Description: This work focuses on the design, synthesis and evaluation of imine-containing heterocyclic and acyclic compounds with special focus on their bioactivity against parasitic protozoans (P. falciparum and T. brucei) - given the context of drug resistance in the treatment of malaria and Human African sleeping sickness and the fact that several bioactive organic compounds have been reported to possess the imino group. Starting from 2-aminopyridine, novel #-alkylated-5-bromo-7-azabenzimidazoles and substituted 5-bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives were prepared, and their bioactivity against parasitic protozoans was assessed. NMR spectra of the substituted 5- bromo-1-(carbamoylmethy)-7-azabenzimidazole derivatives exhibited rotational isomerism, and a dynamic NMR study was used in the estimation of the rate constants and the free- energies of activation for rotation. The free-energy differences between the two rotamers were determined and the more stable conformations were predicted. Novel 2-phenyl-7-azabenzimidazoles were also synthesised from 2-aminopyridine. A convenient method for the regioselective formylation of 2,3-diaminopyridines into 2-amino- 7-(benzylimino)pyridine analogues of 2-phenyl-7-azabenzimidazole was developed, and some of the resulting imino derivatives were hydrogenated to verify the importance of the imino moiety for bioactivity. The 2-phenyl-7-azabenzimidazoles and the 2-amino-7- (benzylimino)pyridine analogues were screened for their anti-protozoal activity and their cytotoxicity level was determined against the HeLa cell line. In order to validate the importance of the pyridine moiety, novel #-(phenyl)-2- hydroxybenzylimines, #-(benzyl)-2-hydroxybenzylimines and (±)-trans-1,2-bis[2- hydroxybenzylimino]cyclohexanes were also synthesized and screened for activity against the parasitic protozoans and for cytotoxicity against the HeLa cell line. The biological assay results indicated that these compounds are not significantly cytotoxic and a good number of them show potential as lead compounds for the development of new malaria and trypanosomiasis drugs. , Thesis (PhD) -- Faculty of Science, Chemistry, 2018
- Full Text:
- Date Issued: 2018
Baculovirus synergism: investigating mixed alphabaculovirus and betabaculovirus infections in the false codling moth, thaumatotibia leucotreta, for improved pest control
- Authors: Jukes, Michael David
- Date: 2018
- Subjects: Baculoviruses , Cryptophlebia leucotreta -- Biological control , Citrus -- Diseases and pests -- South Africa , Pests -- Integrated control , Nucleopolyhedroviruses , Natural pesticides , Cryptophlebia leucotreta granulovirus (CrleGV)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61797 , vital:28061
- Description: Baculovirus based biopesticides are an effective and environmentally friendly approach for the control of agriculturally important insect pests. The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is indigenous to southern Africa and is a major pest of citrus crops. This moth poses a serious risk to export of fruit to foreign markets and the control of this pest is therefore imperative. The Cryptophlebia leucotreta granulovirus (CrleGV) has been commercially formulated into the products Cryptogran™ and Cryptex®. These products have been used successfully for over a decade as part of a rigorous integrated pest management (IPM) programme to control T. leucotreta in South Africa. There is however, a continuous need to improve this programme while also addressing new challenges as they arise. An example of a rising concern is the possibility of resistance developing towards CrleGV. This was seen in Europe with field populations of the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), which developed resistance to the Mexican isolate of the Cydia pomonella granulovirus (CpGV-M). To prevent such a scenario occurring in South Africa, there is a need to improve existing methods of control. For example, additional baculovirus variants can be isolated and characterised for determining virulence, which can then be developed as new biopesticides. Additionally, the potential for synergistic effects between different baculoviruses infecting the same host can be explored for improved virulence. A novel nucleopolyhedrovirus was recently identified in T. leucotreta larval homogenates which were also infected with CrleGV. This provided unique opportunities for continued research and development. In this study, a method using C. pomonella larvae, which can be infected by the NPV but not by CrleGV, was developed to separate the NPV from GV-NPV mixtures in an in vivo system. Examination of NPV OBs by transmission electron microscopy showed purified occlusion bodies with a single nucleopolyhedrovirus morphology (SNPV). Genetic characterisation identified the novel NPV as Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), which was recently isolated from the litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae). To begin examining the potential for synergism between the two viruses, a multiplex PCR assay was developed to accurately detect CrleGV and/or CrpeNPV in mixed infections. This assay was applied to various samples to screen for the presence of CrpeNPV and CrleGV. Additionally, a validation experiment was performed using different combinations of CrpeNPV and/or CrleGV to evaluate the effectiveness of the mPCR assay. The results obtained indicated a high degree of specificity with the correct amplicons generated for each test sample. The biological activity of CrpeNPV and CrleGV were evaluated using surface dose bioassays, both individually and in various combinations, against T. leucotreta neonate larvae in a laboratory setting. A synergistic effect was recorded in the combination treatments, showing improved virulence when compared against each virus in isolation. The LC90 for CrpeNPV and CrleGV when applied alone against T. leucotreta was calculated to be 2.75*106 and 3.00*106 OBs.ml"1 respectively. These values decreased to 1.07*106 and 7.18*105 OBs.ml"1 when combinations of CrleGV and CrpeNPV were applied at ratios of 3:1 and 1:3 respectively. These results indicate a potential for developing improved biopesticides for the control of T. leucotreta in the field. To better understand the interactions between CrleGV and CrpeNPV, experiments involving the serial passage of these viruses through T. leucotreta larvae were performed. This was done using each virus in isolation as well as both viruses in different combinations. Genomic DNA was extracted from recovered occlusion bodies after each passage and examined by multiplex and quantitative PCR. This analysis enabled the detection of each virus present throughout this assay, as well as recording shifts in the ratio of CrleGV and CrpeNPV at each passage. CrleGV rapidly became the dominant virus in all treatments, indicating a potentially antagonistic interaction during serial passage. Additionally, CrpeNPV and CrleGV were detected in treatments which were not originally inoculated with one or either virus, indicating potential covert infections in T. leucotreta. Occlusion bodies recovered from the final passage were used to inoculate C. pomonella larvae to isolate CrpeNPV from CrleGV. Genomic DNA was extracted from these CrpeNPV OBs and examined by restriction endonuclease assays and next generation sequencing. This enabled the identification of potential recombination events which may have occurred during the dual GV and NPV infections throughout the passage assay. No recombination events were identified in the CrpeNPV genome sequences assembled from virus collected at the end of the passage assay. Lastly, the efficacy of CrpeNPV and CrleGV, both alone and in various combinations, was evaluated in the field. In two separate trials conducted on citrus, unfavorable field conditions resulted in no significant reduction in fruit infestation for both the virus and chemical treatments. While not statistically significant, virus treatments were recorded to have the lowest levels of fruit infestation with a measured reduction of up to 64 %. This study is the first to report a synergistic effect between CrleGV and CrpeNPV in T. leucotreta. The discovery of beneficial interactions creates an opportunity for the development of novel biopesticides for improved control of this pest in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Jukes, Michael David
- Date: 2018
- Subjects: Baculoviruses , Cryptophlebia leucotreta -- Biological control , Citrus -- Diseases and pests -- South Africa , Pests -- Integrated control , Nucleopolyhedroviruses , Natural pesticides , Cryptophlebia leucotreta granulovirus (CrleGV)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61797 , vital:28061
- Description: Baculovirus based biopesticides are an effective and environmentally friendly approach for the control of agriculturally important insect pests. The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is indigenous to southern Africa and is a major pest of citrus crops. This moth poses a serious risk to export of fruit to foreign markets and the control of this pest is therefore imperative. The Cryptophlebia leucotreta granulovirus (CrleGV) has been commercially formulated into the products Cryptogran™ and Cryptex®. These products have been used successfully for over a decade as part of a rigorous integrated pest management (IPM) programme to control T. leucotreta in South Africa. There is however, a continuous need to improve this programme while also addressing new challenges as they arise. An example of a rising concern is the possibility of resistance developing towards CrleGV. This was seen in Europe with field populations of the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), which developed resistance to the Mexican isolate of the Cydia pomonella granulovirus (CpGV-M). To prevent such a scenario occurring in South Africa, there is a need to improve existing methods of control. For example, additional baculovirus variants can be isolated and characterised for determining virulence, which can then be developed as new biopesticides. Additionally, the potential for synergistic effects between different baculoviruses infecting the same host can be explored for improved virulence. A novel nucleopolyhedrovirus was recently identified in T. leucotreta larval homogenates which were also infected with CrleGV. This provided unique opportunities for continued research and development. In this study, a method using C. pomonella larvae, which can be infected by the NPV but not by CrleGV, was developed to separate the NPV from GV-NPV mixtures in an in vivo system. Examination of NPV OBs by transmission electron microscopy showed purified occlusion bodies with a single nucleopolyhedrovirus morphology (SNPV). Genetic characterisation identified the novel NPV as Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), which was recently isolated from the litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae). To begin examining the potential for synergism between the two viruses, a multiplex PCR assay was developed to accurately detect CrleGV and/or CrpeNPV in mixed infections. This assay was applied to various samples to screen for the presence of CrpeNPV and CrleGV. Additionally, a validation experiment was performed using different combinations of CrpeNPV and/or CrleGV to evaluate the effectiveness of the mPCR assay. The results obtained indicated a high degree of specificity with the correct amplicons generated for each test sample. The biological activity of CrpeNPV and CrleGV were evaluated using surface dose bioassays, both individually and in various combinations, against T. leucotreta neonate larvae in a laboratory setting. A synergistic effect was recorded in the combination treatments, showing improved virulence when compared against each virus in isolation. The LC90 for CrpeNPV and CrleGV when applied alone against T. leucotreta was calculated to be 2.75*106 and 3.00*106 OBs.ml"1 respectively. These values decreased to 1.07*106 and 7.18*105 OBs.ml"1 when combinations of CrleGV and CrpeNPV were applied at ratios of 3:1 and 1:3 respectively. These results indicate a potential for developing improved biopesticides for the control of T. leucotreta in the field. To better understand the interactions between CrleGV and CrpeNPV, experiments involving the serial passage of these viruses through T. leucotreta larvae were performed. This was done using each virus in isolation as well as both viruses in different combinations. Genomic DNA was extracted from recovered occlusion bodies after each passage and examined by multiplex and quantitative PCR. This analysis enabled the detection of each virus present throughout this assay, as well as recording shifts in the ratio of CrleGV and CrpeNPV at each passage. CrleGV rapidly became the dominant virus in all treatments, indicating a potentially antagonistic interaction during serial passage. Additionally, CrpeNPV and CrleGV were detected in treatments which were not originally inoculated with one or either virus, indicating potential covert infections in T. leucotreta. Occlusion bodies recovered from the final passage were used to inoculate C. pomonella larvae to isolate CrpeNPV from CrleGV. Genomic DNA was extracted from these CrpeNPV OBs and examined by restriction endonuclease assays and next generation sequencing. This enabled the identification of potential recombination events which may have occurred during the dual GV and NPV infections throughout the passage assay. No recombination events were identified in the CrpeNPV genome sequences assembled from virus collected at the end of the passage assay. Lastly, the efficacy of CrpeNPV and CrleGV, both alone and in various combinations, was evaluated in the field. In two separate trials conducted on citrus, unfavorable field conditions resulted in no significant reduction in fruit infestation for both the virus and chemical treatments. While not statistically significant, virus treatments were recorded to have the lowest levels of fruit infestation with a measured reduction of up to 64 %. This study is the first to report a synergistic effect between CrleGV and CrpeNPV in T. leucotreta. The discovery of beneficial interactions creates an opportunity for the development of novel biopesticides for improved control of this pest in South Africa.
- Full Text:
- Date Issued: 2018
Students’ perceptions towards the influences of social media on students’ academic engagement at a tertiary institution: a case study on the use of Facebook and Twitter at Rhodes University
- Authors: Moongela, Harry
- Date: 2018
- Subjects: Facebook (Firm) , Twitter (Firm) , Social media in education -- South Africa -- Makhanda , Motivation in education -- South Africa -- Makhanda , Education, Higher -- Effect of technological innovations on -- South Africa -- Makhanda , Rhodes University
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60730 , vital:27823
- Description: The use of social media has become an integral part of student’s academic lives and has had an impact on students’ academic engagement in tertiary institutions. Subsequently, researchers have shown an interest in investigating the impact of social media on students’ academic engagement. Despite the fact that researcher have shown interest, there still remains a limited number of studies that have discussed the effects of social media on students’ academic engagement, particularly within a South African context. Also, studies that have been carried have revealed limited and mixed findings. This study then aims to further investigate whether the exposure of students to social media has an effect on their academic engagement and how tertiary institutions together with students can use social media to improve students’ academic engagement. A qualitative research method using an interpretive (inductive) approach is carried out to find out students’ perceptions towards the use of social media and its influence on students’ academic engagement. The study then reveals recommendations from students’ perceptions on the effective ways of using social media to benefit students’ academic engagement in tertiary institutions.
- Full Text:
- Date Issued: 2018
- Authors: Moongela, Harry
- Date: 2018
- Subjects: Facebook (Firm) , Twitter (Firm) , Social media in education -- South Africa -- Makhanda , Motivation in education -- South Africa -- Makhanda , Education, Higher -- Effect of technological innovations on -- South Africa -- Makhanda , Rhodes University
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60730 , vital:27823
- Description: The use of social media has become an integral part of student’s academic lives and has had an impact on students’ academic engagement in tertiary institutions. Subsequently, researchers have shown an interest in investigating the impact of social media on students’ academic engagement. Despite the fact that researcher have shown interest, there still remains a limited number of studies that have discussed the effects of social media on students’ academic engagement, particularly within a South African context. Also, studies that have been carried have revealed limited and mixed findings. This study then aims to further investigate whether the exposure of students to social media has an effect on their academic engagement and how tertiary institutions together with students can use social media to improve students’ academic engagement. A qualitative research method using an interpretive (inductive) approach is carried out to find out students’ perceptions towards the use of social media and its influence on students’ academic engagement. The study then reveals recommendations from students’ perceptions on the effective ways of using social media to benefit students’ academic engagement in tertiary institutions.
- Full Text:
- Date Issued: 2018
An investigation into the introduction of a new wealth tax in South Africa
- Authors: Arendse, Jacqueline A
- Date: 2018
- Subjects: Wealth tax -- Law and legislation -- South Africa , Taxation -- Law and legislation -- South Africa , Income tax -- South Africa , Fiscal policy -- South Africa , South Africa -- Economic conditions , Income distribution -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61379 , vital:28020
- Description: In a world of economic uncertainty and manifold social problems, South Africa has its own unique challenges of low economic growth, persistent budget deficits that produce increasing government debt and the highest level of economic inequality in the world. The history of injustice and economic marginalisation and the failure of the economy to provide inclusive growth drives an urgent need to address economic inequality through tax policy, placing ever more focus on wealth taxes as a possible solution. There is a hope is that taxing the wealthy may provide the opportunity to redistribute desperately-needed resources to those denied the opportunity to build wealth and who are trapped in the cycle of poverty. Yet, as appealing as a new wealth tax may seem, the introduction of such a tax carries with it a range of risks, not all of which are known. Of great concern is the possible effect on the economy, which, in its vulnerable state, cannot afford any loss of capital and investment. Very little research has been done on wealth tax in the South African context and there is a dearth of literature focusing on the views and perceptions of the wealthy individuals themselves. This qualitative study investigates the merits and disadvantages of a new wealth tax and seeks to identify any unintended consequences that could result from the implementation of a new wealth tax in South Africa, drawing from historical and international experience and primary data obtained from interviews with individuals likely to be affected by such a tax. Having explored the literature and international experiences with wealth tax and having probed the thinking of wealthy individuals who would be the payers of a wealth tax, the study finds that a new wealth tax may contribute towards the progressivity of the tax system, but it is doubtful whether such a tax would provide a sustainable revenue stream that would be sufficient to address economic inequality and there is a risk of causing harm to the economy. Recognising that the motivation for wealth taxes is often driven more by political argument and public perception than by rational quantitative analysis, the study also anticipates the introduction of a new wealth tax and suggests guidelines for the design of such a tax within the framework for evaluating a good tax system. This study informs the debate on wealth taxes in South Africa and contributes to the design of such a tax, should it be implemented.
- Full Text:
- Date Issued: 2018
- Authors: Arendse, Jacqueline A
- Date: 2018
- Subjects: Wealth tax -- Law and legislation -- South Africa , Taxation -- Law and legislation -- South Africa , Income tax -- South Africa , Fiscal policy -- South Africa , South Africa -- Economic conditions , Income distribution -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61379 , vital:28020
- Description: In a world of economic uncertainty and manifold social problems, South Africa has its own unique challenges of low economic growth, persistent budget deficits that produce increasing government debt and the highest level of economic inequality in the world. The history of injustice and economic marginalisation and the failure of the economy to provide inclusive growth drives an urgent need to address economic inequality through tax policy, placing ever more focus on wealth taxes as a possible solution. There is a hope is that taxing the wealthy may provide the opportunity to redistribute desperately-needed resources to those denied the opportunity to build wealth and who are trapped in the cycle of poverty. Yet, as appealing as a new wealth tax may seem, the introduction of such a tax carries with it a range of risks, not all of which are known. Of great concern is the possible effect on the economy, which, in its vulnerable state, cannot afford any loss of capital and investment. Very little research has been done on wealth tax in the South African context and there is a dearth of literature focusing on the views and perceptions of the wealthy individuals themselves. This qualitative study investigates the merits and disadvantages of a new wealth tax and seeks to identify any unintended consequences that could result from the implementation of a new wealth tax in South Africa, drawing from historical and international experience and primary data obtained from interviews with individuals likely to be affected by such a tax. Having explored the literature and international experiences with wealth tax and having probed the thinking of wealthy individuals who would be the payers of a wealth tax, the study finds that a new wealth tax may contribute towards the progressivity of the tax system, but it is doubtful whether such a tax would provide a sustainable revenue stream that would be sufficient to address economic inequality and there is a risk of causing harm to the economy. Recognising that the motivation for wealth taxes is often driven more by political argument and public perception than by rational quantitative analysis, the study also anticipates the introduction of a new wealth tax and suggests guidelines for the design of such a tax within the framework for evaluating a good tax system. This study informs the debate on wealth taxes in South Africa and contributes to the design of such a tax, should it be implemented.
- Full Text:
- Date Issued: 2018
Graphite: origin, deposits and economics : an exploration study of the Orom Graphite project
- Van den Berg, Jacobus Petrus
- Authors: Van den Berg, Jacobus Petrus
- Date: 2018
- Subjects: Graphite , Ore deposits , Geophysics , Graphite mines and mining Economic aspects Africa, East , Trenches , Project management
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63786 , vital:28489
- Description: Developing exploration projects successfully requires that the Reasonable Prospects for Eventual Economic Extraction (RPEEE) be confirmed and based on the global market perception and trend. The exploration methods applied in the attempt to establish this RPEEE must be based on a key management framework that assures the results, and eventually the conclusion, are obtained with best practical and technical approaches whilst managing the risks and capitalizing on each result. The Orom Graphite project is located within the East African Orogenic belt, a suture zone between the Congo craton and the SLAMIN shield, formed during the formation of Gondwana during the late Proterozoic to early-Phanerozoic era. The closing of the Mozambique ocean, and the eventual collision between the craton and shield, occurred along the paleo-earths equator and migrated towards lower latitudes. This, along with the period’s biodiversity boom, provided the perfect deposition environment for carbonaceous sediments which were later metamorphosed to amphibolite and granulites grade metamorphism, resulting in the carbonization and the eventual graphitization of these carbonaceous sediments. The project is located within a poorly developed part of Uganda with the closest port situated some 1 500 km to the east in Kenya. The poorly developed infrastructure along with probable high logistical cost assigns a low competitivity index if compared to the economic costs of peer projects. However, the potential resources of the Orom Graphite project suggest that the Life of Mine (LOM) can rival the largest resource currently reported within the market. The current market conditions suggest that a possible oversupply of graphite concentrate will dominate the market within the next 4 to 10 years. This suggests that new graphite projects such as the Orom Graphite project are likely to develop into the production phase once the global supply and demand stabilize. This requires the Orom Graphite project to develop from its current scoping study level to a project development study level associated with a definitive feasibility study. To date, the project developed through mapping, reconnaissance drilling, geophysical survey and trenching programs increasing the Net Present Value (NPV) considerably based upon a Cost-Based Valuation approach using Prospectivity Enhancement Multiplier (PEM). The metallurgical studies could however not produce a graphite concentrate product within industrial grade standards. The risk associated with developing the project further into the Mineral Resource Estimation (MRE) phase was quantified and risk was evaluated by implementing a point decision tree and calculating the Expected Monetary Value (EMV). Due to the unfavourable metallurgical results obtained to date, the risk associated with undertaking an additional metallurgical test is considerable with a slight chance of producing a negative project value estimated at 65%. JP van den Berg Rhodes University Overall, the Orom Graphite project contains favourable geological formations with a potential large resource. Market trends indicate that a considerable resource is currently being developed and can supply the global market for the next 4 to 10 years. The project’s location within a landlocked country decreases its economic competitiveness with peer project and the unfavourable, but not conclusive, metallurgical results obtained during the scoping phase do not instil confidence that the project will develop into a productive mine soon. Managing the project development with future graphite demand in mind is the key to determining whether the project still has future value.
- Full Text:
- Date Issued: 2018
- Authors: Van den Berg, Jacobus Petrus
- Date: 2018
- Subjects: Graphite , Ore deposits , Geophysics , Graphite mines and mining Economic aspects Africa, East , Trenches , Project management
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63786 , vital:28489
- Description: Developing exploration projects successfully requires that the Reasonable Prospects for Eventual Economic Extraction (RPEEE) be confirmed and based on the global market perception and trend. The exploration methods applied in the attempt to establish this RPEEE must be based on a key management framework that assures the results, and eventually the conclusion, are obtained with best practical and technical approaches whilst managing the risks and capitalizing on each result. The Orom Graphite project is located within the East African Orogenic belt, a suture zone between the Congo craton and the SLAMIN shield, formed during the formation of Gondwana during the late Proterozoic to early-Phanerozoic era. The closing of the Mozambique ocean, and the eventual collision between the craton and shield, occurred along the paleo-earths equator and migrated towards lower latitudes. This, along with the period’s biodiversity boom, provided the perfect deposition environment for carbonaceous sediments which were later metamorphosed to amphibolite and granulites grade metamorphism, resulting in the carbonization and the eventual graphitization of these carbonaceous sediments. The project is located within a poorly developed part of Uganda with the closest port situated some 1 500 km to the east in Kenya. The poorly developed infrastructure along with probable high logistical cost assigns a low competitivity index if compared to the economic costs of peer projects. However, the potential resources of the Orom Graphite project suggest that the Life of Mine (LOM) can rival the largest resource currently reported within the market. The current market conditions suggest that a possible oversupply of graphite concentrate will dominate the market within the next 4 to 10 years. This suggests that new graphite projects such as the Orom Graphite project are likely to develop into the production phase once the global supply and demand stabilize. This requires the Orom Graphite project to develop from its current scoping study level to a project development study level associated with a definitive feasibility study. To date, the project developed through mapping, reconnaissance drilling, geophysical survey and trenching programs increasing the Net Present Value (NPV) considerably based upon a Cost-Based Valuation approach using Prospectivity Enhancement Multiplier (PEM). The metallurgical studies could however not produce a graphite concentrate product within industrial grade standards. The risk associated with developing the project further into the Mineral Resource Estimation (MRE) phase was quantified and risk was evaluated by implementing a point decision tree and calculating the Expected Monetary Value (EMV). Due to the unfavourable metallurgical results obtained to date, the risk associated with undertaking an additional metallurgical test is considerable with a slight chance of producing a negative project value estimated at 65%. JP van den Berg Rhodes University Overall, the Orom Graphite project contains favourable geological formations with a potential large resource. Market trends indicate that a considerable resource is currently being developed and can supply the global market for the next 4 to 10 years. The project’s location within a landlocked country decreases its economic competitiveness with peer project and the unfavourable, but not conclusive, metallurgical results obtained during the scoping phase do not instil confidence that the project will develop into a productive mine soon. Managing the project development with future graphite demand in mind is the key to determining whether the project still has future value.
- Full Text:
- Date Issued: 2018
An analysis of the implementation of the Teaching Development Grant in the South African Higher Education Sector
- Authors: Moyo, Mtheto Temwa
- Date: 2018
- Subjects: Education, Higher -- Aims and objectives -- South Africa , Government aid to higher education -- South Africa , Education, Higher -- South Africa -- Evaluation , Education, Higher -- Social aspects -- South Africa , Educational leadership -- South Africa , Educational equalization -- South Africa , Education, Higher -- Economic aspects -- South Africa , Teaching Development Grant (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62225 , vital:28141
- Description: The South African government has attempted to address various transformation and efficiency challenges in the system through the steering mechanisms at its disposal. This study analyses the implementation of one of these mechanisms, the Teaching Development Grant (TDG), which is designed to enhance student learning through the improvement of teaching and teaching resources at South African universities. Since the inception as an earmarked grant ten years ago, a total of R5.5 billion has been allocated for the TDG. The study thus sought to answer the question: What are the factors enabling and constraining the use of the TDG to enhance teaching and student success at South African universities? A total of 275 TDG progress reports and budget plans were analysed alongside other TDG documentation such as TDG payment letters to universities and institutional submissions that universities made on the use of the TDG for the 2008 TDG Review. The TDG criteria and policy over the years were also included as data. The analysis used Archer’s (1995; 1996) morphogenesis/stasis framework, which is concerned with how change does or does not happen over time. Archer’s analytical dualism was used to identify the interplay of structural, cultural and agential mechanisms shaping the emergence of and practices associated with TDGs in order to make sense of the events and experiences in the data. One of the main findings of the study was that the historically-based differentiated nature of the South African higher education landscape constrained the implementation of the TDG. The stark resource differences in the sector has meant that the TDG has not fully translated into system-wide gains. In the initial years of TDG implementation from 2004 to 2013, most institutions did not use the TDG for teaching development initiatives per se, but rather spent the bulk of the funds on infrastructure and equipment. Such resource gaps have persisted and continue to compromise the academic enterprise at affected universities. The data also showed that universities which have access to additional funding other than state funding have been able to augment and advance their own funds and were thus able to at least partially counter late payments of the TDG, fluctuations in allocations, and the short-term nature of TDG budgets and inadequate allocations. This enabled relatively straightforward implementation of the teaching and learning enhancement programmes at these universities, while there were ongoing implementation difficulties at the universities with the lowest success rates, the very institutions the grant was most targeted to address. The study showed that the shortage of appropriate teaching and learning staff constrained the nature and type of interventions. Historically Disadvantaged Institutions in particular struggled to attract and retain the much-needed expertise. This emerged from multiple structural constraints such as geographical location, conditions of work, inefficient human resources systems, lack of access to financial resources for competitive packages, and instability in governance and management structures at some universities. Emerging from the data in the study is the fact that staffing challenges remain one of the core constraints in the implementation of the TDG. In particular, the data indicated that teaching and learning staff hired on the basis of TDG funds were generally hired as part-time or contract staff. This meant that their academic qualifications and experience in teaching development were limited and, in many cases, it meant that the posts were not filled at all. In some cases, the fluctuating budgets meant that some projects had to be downscaled or abandoned altogether. The study found that many of the interventions that were implemented had tenuous links to teaching and learning and, even where there were such links, these interventions were often based on fairly a-theoretical, common-sense understandings of what would develop teaching. In many universities, there was little evidence of institution-level planning of interventions aimed at fundamentally addressing the need for teaching development. The limited access to teaching and learning expertise across the sector was mirrored in the uneven distribution of expertise in administration, financial management, institutional planning and human resource divisions, which had implications for the establishment of monitoring systems and implementation processes of the TDG. The lack of strong systems and policies encouraged cultures that did not value transparency, accountability or compliance to the TDG policy. The role of corporate agency in the form of leadership and ownership of projects emerged as a key enabler in the implementation of the TDG. All of these structures shaped the ability of institutions to spend the TDG and in some cases millions of Rands in funds were not spent and so were withheld. The study found that the inability of some universities to spend was exacerbated by the problem of a lack of alignment between the DHET financial year and the academic year. Although the TDG has made a notable contribution to the advancement of teaching and learning (T&L) nationally, this study revealed that the blunt implementation of the TDG across the sector constrained the gains. In particular, the practice of withholding unspent funds focused only on the symptoms of underspending and not on the structural, cultural and agential mechanisms that led to such under-expenditure. The withheld funds were redirected by the government for national projects but as all universities including the well-resourced Historically Advantaged Institutions (HAIs) had access to these withheld funds this translated into a regressive distribution of the TDG. Limited capacity within DHET to direct, manage and monitor the grants has also had a constraining effect on their use and the secondment of a teaching and learning expert to the department was seen to be a significant but short-term enablement in this regard. The findings of how the TDG implementation has emerged in the South African higher education sector are particularly important at this point in time as the TDG together with the Research Development Grant will be reconfigured into a new grant called the University Capacity Development Grant as from 2018. This study provides significant insights into the structural, cultural, and agential enablements and constraints of this new grant being able to drive changes in the sector. The findings also provide insights into the implementation of other earmarked grants. , Boma la South Africa layesera kuthetsa mavuto omwe amadza posintha ndi kulongosola zinthu kudzera mu njira zosiyanasiyana. Kafukufukuyu akuunikira imodzi mwa njirazi yotchedwa Teaching Development Grant (TDG) yomwe inakonzedwa polimbikitsa maphunziro kudzera mukagwiritsidwe ntchito ka zipangizo zophunzitsira ndi zophunzirira za makono m’sukulu za ukachenjede ku South Africa. Ndalama zapafupifupi R5.5 billion ndi zomwe zaperekedwa kuti zigwiritsidwe nchito mu ndondomekoyi kuchokera pa nthawi yomwe inakhazikitsidwa; zaka khumi zapitazo. Kafukufukuyu anayesera kuyankha funso loti: Ndi zinthu ziti zomwe zimalimbikitsa kapena kubwezeretsa m’mbuyo kagwiritsidwe ntchito ka (TDG) polimbikitsa kuchita bwino kwa aphunzitsi ndi ophunzira m’sukulu za ukachenjede? Zikalata zosonyeza makhonzedwe a ophunzira, ndondomeko za kayendetseredwe ka chuma, zikalata za malipiridwe ndi zikalata zopezeka m’sukulu zaukachenjedezi zokhudzana ndi njira ya TDG zomwe zakhala zikugwiritsidwa ntchito zaka khumi zapitazi zinatengedwanso ngati uthenga wofunika koposa. Kauniuniyu anatsalira njira yotchedwa ‘Archer’s (1995/1996) Morphogenesis/Status Framework’ yomwe imafotokozera momwe kusintha kumachitikira pena kulepherekera. Njira younikira ya Archer: yothandizira pofufuza momwe kayendetsedwe ka bungwe, chikhalidwe komanso anthu oyendetsa bungwe amathandizira poonetsera momwe TDG imakhalira inagwiritsidwa ntchito poyesera kumvetsa zochitika komanso zopezeka mu kafukufukuyu. Chimodzi mwa zotsatira za kafukufukuyu n’chakuti kagwiritsidwe ntchito ka TDG kamabwezeredwa m’mbuyo ndi momwe sukulu za ukachenjede ku South Africa zidapangidwira. Kusiyana kwa usiwa wa zipangizo m’sukuluzi kudapangitsa kuti njira ya TDG isaonetse zipatso kwenikweni. Mu zaka zoyambirira itangokhazikidwitsa (2007 - 2013), sukulu zambiri sizidagwiritse ntchito TDG polimbikitsa kaphunzitsidwe. M’malo mwake ndalama zankhaninkhani zidagwiritsidwa ntchito pa zomangamanga ndi kugulira zipangizo. Usiwa wa zipangizowu ulipobe ndipo ukusokoneza mbali ya maphunziro m’sukulu zokhudzidwazi. Kafukufukuyu anasonyezanso kuti sukulu zomwe zimalandira thandizo lowonjezera pa lomwe zimalandira ku boma zakhala zikuyesetsa kuthana ndi vuto lopereka mochedwa ndalama za mundondomeko ya TDG ndi dongosolo la m’mene ndalamazi zigwirire ntchito. Izi zinawachititsa kuti asapeze mavuto ambiri polimbikitsa ndondomeko za kaphunzitsidwe ndi kaphunziridwe pomwe ena amavutika nazo. Enawa n’kukhala sukulu zomwe sizimachita bwino, zomwenso thandizoli lidalunjika pa izo kuti zithandizike. Kafukufukuyu anasonyeza kuti kuchepa kwa aphunzitsi kudapsinja zochitika zokhudza njirayi. Sukulu zosachita bwino kuchokera kalezi zidavutika kupeza ndi kusunga ogwira ntchito ake. Izi zimakhala choncho kaamba ka zifukwa zosiyanasiyana monga komwe sukuluyo ili, malamulo a ntchito, kupanda ukadaulo kwa oyang’anira antchitowa, kutalikirana ndi njira zina zopezera ndalama komanso kusakhazikika kwa anthu m’maudindo. Zina zotulukanso mu mfundo zotoledwazi zinaulula kuti vuto lina lalikulu linali ogwira ntchito. Polimbikitsa njira ya TDG, zimatanthauza kuti aphunzitsi omwe azilembedwa azikhala osakhazikika pa sukuluzi kapena a kontarakiti. Izi zimatanthauza kuti maphunziro ndi luntha lawo zimayenera kukhala zochepera. Mwanjira ina, tikhonza kunena kuti ogwira ntchitoyi panalibe. Nthawi zina, kusinthasintha kwa ndondomeko zachuma madongosolo ena kusiyidwa kapena kuchitika mosalongosoka. Kafukufukuyu anasonyezanso kuti zambiri mwa mfundo zomwe zinayikidwa kuti zigwiritsidwe ntchito zinali zosathandiza kwenikweni polimbikitsa maphunzirowa. Ndipo komwe mfundozi zinakhazikitsidwa, zinali chabe kufotokozera zinthu zodziwika kale ndi kale zokhudza zomwe zingalimbikitse uphunzitsi. M’sukulu zambiri za ukachenjede, pali umboni wochepa wa mfundo zomwe zinaikidwiratu ndi cholinga chopititsa patsogolo uphunzitsiwu. Kusowa kwa ukadaulo pa maphunzirowa kunaonekanso makamaka m’madera monga a oyendetsa sukuluzi, oyang’ana za chuma, olongosola malo onse komanso oyang’anira antchito. Panalibe kugawana anthuwa mofanana. Izi zidakhudza kwambiri kalondolondo ndinso kayendetsedwe ka TDG. Kusowa kwa ndondomeko zabwino ndi malamulo okhazikika kunalimbikitsa chikhalidwe cha chinyengo ndi kusatsatira mfundo za mundondomekoyi popereka utsogoleri ndi umwini ndiye unali wofunika polimbikitsa ndondomekoyi. Madongosolo otere anathandiza kuti sukulu zigwiritse ntchito njira ya TDG ndipo pena ndalama mamiliyoni zibwezedwe. Kafukufukuyu anaonetsa kuti kulephera kwa sukulu zina kugwiritsa ntchito ndalama kunachitika kaamba kosazindikira malire a chaka cha DHET ndi chaka cha maphunziro. Ngakhale njira ya TDG yathandizako kagwiritsidwe ntchito ka zipangizo zophunzitsira ndi zophunzirira, kafukufukuyu wasonyeza kuti mavuto omwe anaoneka mu ndondomeko ya TDG aphimba ubwino wake. Monga, m’chitidwe wobweza ndalama zosagwira ntchito unalunjika pa kulephera kugwiritsa ntchito ndalama zonse osati pa ubale pakati pa kayendetsedwe ka bungwe, chikhalidwe ndinso anthu oyendetsa bungwe. Ndalama zotsarazi zinalowetsedwa ku zitukuko zina ndi boma. Koma poti sukulu zonse za ukachenjede kuphatikizapo HAI zinapeza mwayi wa ndalamazi, izi zimabweretsa kulowa pansi kwa dongosolo la TDG. Kulephera mu DHET kutsogolera, kuyendetsa ndi kulondoloza thandizo kwadzetsanso mavuto pa kagwiritsidwe ntchito kake ngakhalenso kutumizidwa kwa katswiri pa kaphunzitsidwe kunaoneka ngati kofunika kosathandiza kwenikweni chifukwa kudali kwa nthawi yochepa. Zotsatira za kafukufukuyu (zokhudza maphunziro a ukachenjede ku South Africa) ndi zofunika kwambiri makamaka nthawi ino pomwe TDG pamodzi ndi RDG (Research Development Grant) zikhale kuunikiridwanso ndi kupanga thandizo latsopano lotchedwa University Capacity Development Grant kuyambira m’chaka cha 2018. Kafukufukuyu waunika mozama kayendetsedwe, chikhalidwe komanso oyendetsa zithandizo komanso mavuto kuti thandizo latsopanoli likathe kubweretsa kusintha. Zotsatirazi zaunikiranso kayendetsedwe ka zithandizo zina zomwe zikufuna kuchitika.
- Full Text:
- Date Issued: 2018
- Authors: Moyo, Mtheto Temwa
- Date: 2018
- Subjects: Education, Higher -- Aims and objectives -- South Africa , Government aid to higher education -- South Africa , Education, Higher -- South Africa -- Evaluation , Education, Higher -- Social aspects -- South Africa , Educational leadership -- South Africa , Educational equalization -- South Africa , Education, Higher -- Economic aspects -- South Africa , Teaching Development Grant (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62225 , vital:28141
- Description: The South African government has attempted to address various transformation and efficiency challenges in the system through the steering mechanisms at its disposal. This study analyses the implementation of one of these mechanisms, the Teaching Development Grant (TDG), which is designed to enhance student learning through the improvement of teaching and teaching resources at South African universities. Since the inception as an earmarked grant ten years ago, a total of R5.5 billion has been allocated for the TDG. The study thus sought to answer the question: What are the factors enabling and constraining the use of the TDG to enhance teaching and student success at South African universities? A total of 275 TDG progress reports and budget plans were analysed alongside other TDG documentation such as TDG payment letters to universities and institutional submissions that universities made on the use of the TDG for the 2008 TDG Review. The TDG criteria and policy over the years were also included as data. The analysis used Archer’s (1995; 1996) morphogenesis/stasis framework, which is concerned with how change does or does not happen over time. Archer’s analytical dualism was used to identify the interplay of structural, cultural and agential mechanisms shaping the emergence of and practices associated with TDGs in order to make sense of the events and experiences in the data. One of the main findings of the study was that the historically-based differentiated nature of the South African higher education landscape constrained the implementation of the TDG. The stark resource differences in the sector has meant that the TDG has not fully translated into system-wide gains. In the initial years of TDG implementation from 2004 to 2013, most institutions did not use the TDG for teaching development initiatives per se, but rather spent the bulk of the funds on infrastructure and equipment. Such resource gaps have persisted and continue to compromise the academic enterprise at affected universities. The data also showed that universities which have access to additional funding other than state funding have been able to augment and advance their own funds and were thus able to at least partially counter late payments of the TDG, fluctuations in allocations, and the short-term nature of TDG budgets and inadequate allocations. This enabled relatively straightforward implementation of the teaching and learning enhancement programmes at these universities, while there were ongoing implementation difficulties at the universities with the lowest success rates, the very institutions the grant was most targeted to address. The study showed that the shortage of appropriate teaching and learning staff constrained the nature and type of interventions. Historically Disadvantaged Institutions in particular struggled to attract and retain the much-needed expertise. This emerged from multiple structural constraints such as geographical location, conditions of work, inefficient human resources systems, lack of access to financial resources for competitive packages, and instability in governance and management structures at some universities. Emerging from the data in the study is the fact that staffing challenges remain one of the core constraints in the implementation of the TDG. In particular, the data indicated that teaching and learning staff hired on the basis of TDG funds were generally hired as part-time or contract staff. This meant that their academic qualifications and experience in teaching development were limited and, in many cases, it meant that the posts were not filled at all. In some cases, the fluctuating budgets meant that some projects had to be downscaled or abandoned altogether. The study found that many of the interventions that were implemented had tenuous links to teaching and learning and, even where there were such links, these interventions were often based on fairly a-theoretical, common-sense understandings of what would develop teaching. In many universities, there was little evidence of institution-level planning of interventions aimed at fundamentally addressing the need for teaching development. The limited access to teaching and learning expertise across the sector was mirrored in the uneven distribution of expertise in administration, financial management, institutional planning and human resource divisions, which had implications for the establishment of monitoring systems and implementation processes of the TDG. The lack of strong systems and policies encouraged cultures that did not value transparency, accountability or compliance to the TDG policy. The role of corporate agency in the form of leadership and ownership of projects emerged as a key enabler in the implementation of the TDG. All of these structures shaped the ability of institutions to spend the TDG and in some cases millions of Rands in funds were not spent and so were withheld. The study found that the inability of some universities to spend was exacerbated by the problem of a lack of alignment between the DHET financial year and the academic year. Although the TDG has made a notable contribution to the advancement of teaching and learning (T&L) nationally, this study revealed that the blunt implementation of the TDG across the sector constrained the gains. In particular, the practice of withholding unspent funds focused only on the symptoms of underspending and not on the structural, cultural and agential mechanisms that led to such under-expenditure. The withheld funds were redirected by the government for national projects but as all universities including the well-resourced Historically Advantaged Institutions (HAIs) had access to these withheld funds this translated into a regressive distribution of the TDG. Limited capacity within DHET to direct, manage and monitor the grants has also had a constraining effect on their use and the secondment of a teaching and learning expert to the department was seen to be a significant but short-term enablement in this regard. The findings of how the TDG implementation has emerged in the South African higher education sector are particularly important at this point in time as the TDG together with the Research Development Grant will be reconfigured into a new grant called the University Capacity Development Grant as from 2018. This study provides significant insights into the structural, cultural, and agential enablements and constraints of this new grant being able to drive changes in the sector. The findings also provide insights into the implementation of other earmarked grants. , Boma la South Africa layesera kuthetsa mavuto omwe amadza posintha ndi kulongosola zinthu kudzera mu njira zosiyanasiyana. Kafukufukuyu akuunikira imodzi mwa njirazi yotchedwa Teaching Development Grant (TDG) yomwe inakonzedwa polimbikitsa maphunziro kudzera mukagwiritsidwe ntchito ka zipangizo zophunzitsira ndi zophunzirira za makono m’sukulu za ukachenjede ku South Africa. Ndalama zapafupifupi R5.5 billion ndi zomwe zaperekedwa kuti zigwiritsidwe nchito mu ndondomekoyi kuchokera pa nthawi yomwe inakhazikitsidwa; zaka khumi zapitazo. Kafukufukuyu anayesera kuyankha funso loti: Ndi zinthu ziti zomwe zimalimbikitsa kapena kubwezeretsa m’mbuyo kagwiritsidwe ntchito ka (TDG) polimbikitsa kuchita bwino kwa aphunzitsi ndi ophunzira m’sukulu za ukachenjede? Zikalata zosonyeza makhonzedwe a ophunzira, ndondomeko za kayendetseredwe ka chuma, zikalata za malipiridwe ndi zikalata zopezeka m’sukulu zaukachenjedezi zokhudzana ndi njira ya TDG zomwe zakhala zikugwiritsidwa ntchito zaka khumi zapitazi zinatengedwanso ngati uthenga wofunika koposa. Kauniuniyu anatsalira njira yotchedwa ‘Archer’s (1995/1996) Morphogenesis/Status Framework’ yomwe imafotokozera momwe kusintha kumachitikira pena kulepherekera. Njira younikira ya Archer: yothandizira pofufuza momwe kayendetsedwe ka bungwe, chikhalidwe komanso anthu oyendetsa bungwe amathandizira poonetsera momwe TDG imakhalira inagwiritsidwa ntchito poyesera kumvetsa zochitika komanso zopezeka mu kafukufukuyu. Chimodzi mwa zotsatira za kafukufukuyu n’chakuti kagwiritsidwe ntchito ka TDG kamabwezeredwa m’mbuyo ndi momwe sukulu za ukachenjede ku South Africa zidapangidwira. Kusiyana kwa usiwa wa zipangizo m’sukuluzi kudapangitsa kuti njira ya TDG isaonetse zipatso kwenikweni. Mu zaka zoyambirira itangokhazikidwitsa (2007 - 2013), sukulu zambiri sizidagwiritse ntchito TDG polimbikitsa kaphunzitsidwe. M’malo mwake ndalama zankhaninkhani zidagwiritsidwa ntchito pa zomangamanga ndi kugulira zipangizo. Usiwa wa zipangizowu ulipobe ndipo ukusokoneza mbali ya maphunziro m’sukulu zokhudzidwazi. Kafukufukuyu anasonyezanso kuti sukulu zomwe zimalandira thandizo lowonjezera pa lomwe zimalandira ku boma zakhala zikuyesetsa kuthana ndi vuto lopereka mochedwa ndalama za mundondomeko ya TDG ndi dongosolo la m’mene ndalamazi zigwirire ntchito. Izi zinawachititsa kuti asapeze mavuto ambiri polimbikitsa ndondomeko za kaphunzitsidwe ndi kaphunziridwe pomwe ena amavutika nazo. Enawa n’kukhala sukulu zomwe sizimachita bwino, zomwenso thandizoli lidalunjika pa izo kuti zithandizike. Kafukufukuyu anasonyeza kuti kuchepa kwa aphunzitsi kudapsinja zochitika zokhudza njirayi. Sukulu zosachita bwino kuchokera kalezi zidavutika kupeza ndi kusunga ogwira ntchito ake. Izi zimakhala choncho kaamba ka zifukwa zosiyanasiyana monga komwe sukuluyo ili, malamulo a ntchito, kupanda ukadaulo kwa oyang’anira antchitowa, kutalikirana ndi njira zina zopezera ndalama komanso kusakhazikika kwa anthu m’maudindo. Zina zotulukanso mu mfundo zotoledwazi zinaulula kuti vuto lina lalikulu linali ogwira ntchito. Polimbikitsa njira ya TDG, zimatanthauza kuti aphunzitsi omwe azilembedwa azikhala osakhazikika pa sukuluzi kapena a kontarakiti. Izi zimatanthauza kuti maphunziro ndi luntha lawo zimayenera kukhala zochepera. Mwanjira ina, tikhonza kunena kuti ogwira ntchitoyi panalibe. Nthawi zina, kusinthasintha kwa ndondomeko zachuma madongosolo ena kusiyidwa kapena kuchitika mosalongosoka. Kafukufukuyu anasonyezanso kuti zambiri mwa mfundo zomwe zinayikidwa kuti zigwiritsidwe ntchito zinali zosathandiza kwenikweni polimbikitsa maphunzirowa. Ndipo komwe mfundozi zinakhazikitsidwa, zinali chabe kufotokozera zinthu zodziwika kale ndi kale zokhudza zomwe zingalimbikitse uphunzitsi. M’sukulu zambiri za ukachenjede, pali umboni wochepa wa mfundo zomwe zinaikidwiratu ndi cholinga chopititsa patsogolo uphunzitsiwu. Kusowa kwa ukadaulo pa maphunzirowa kunaonekanso makamaka m’madera monga a oyendetsa sukuluzi, oyang’ana za chuma, olongosola malo onse komanso oyang’anira antchito. Panalibe kugawana anthuwa mofanana. Izi zidakhudza kwambiri kalondolondo ndinso kayendetsedwe ka TDG. Kusowa kwa ndondomeko zabwino ndi malamulo okhazikika kunalimbikitsa chikhalidwe cha chinyengo ndi kusatsatira mfundo za mundondomekoyi popereka utsogoleri ndi umwini ndiye unali wofunika polimbikitsa ndondomekoyi. Madongosolo otere anathandiza kuti sukulu zigwiritse ntchito njira ya TDG ndipo pena ndalama mamiliyoni zibwezedwe. Kafukufukuyu anaonetsa kuti kulephera kwa sukulu zina kugwiritsa ntchito ndalama kunachitika kaamba kosazindikira malire a chaka cha DHET ndi chaka cha maphunziro. Ngakhale njira ya TDG yathandizako kagwiritsidwe ntchito ka zipangizo zophunzitsira ndi zophunzirira, kafukufukuyu wasonyeza kuti mavuto omwe anaoneka mu ndondomeko ya TDG aphimba ubwino wake. Monga, m’chitidwe wobweza ndalama zosagwira ntchito unalunjika pa kulephera kugwiritsa ntchito ndalama zonse osati pa ubale pakati pa kayendetsedwe ka bungwe, chikhalidwe ndinso anthu oyendetsa bungwe. Ndalama zotsarazi zinalowetsedwa ku zitukuko zina ndi boma. Koma poti sukulu zonse za ukachenjede kuphatikizapo HAI zinapeza mwayi wa ndalamazi, izi zimabweretsa kulowa pansi kwa dongosolo la TDG. Kulephera mu DHET kutsogolera, kuyendetsa ndi kulondoloza thandizo kwadzetsanso mavuto pa kagwiritsidwe ntchito kake ngakhalenso kutumizidwa kwa katswiri pa kaphunzitsidwe kunaoneka ngati kofunika kosathandiza kwenikweni chifukwa kudali kwa nthawi yochepa. Zotsatira za kafukufukuyu (zokhudza maphunziro a ukachenjede ku South Africa) ndi zofunika kwambiri makamaka nthawi ino pomwe TDG pamodzi ndi RDG (Research Development Grant) zikhale kuunikiridwanso ndi kupanga thandizo latsopano lotchedwa University Capacity Development Grant kuyambira m’chaka cha 2018. Kafukufukuyu waunika mozama kayendetsedwe, chikhalidwe komanso oyendetsa zithandizo komanso mavuto kuti thandizo latsopanoli likathe kubweretsa kusintha. Zotsatirazi zaunikiranso kayendetsedwe ka zithandizo zina zomwe zikufuna kuchitika.
- Full Text:
- Date Issued: 2018
Strength and conditioning practices of high school rugby coaches: a South African context
- Authors: Robinson, Bradley Charles
- Date: 2018
- Subjects: Rugby football coaches South Africa , Rugby football Coaching , Rugby football Physiological aspects , Rugby football Training , High school students Social conditions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63459 , vital:28413
- Description: Although the sport of rugby union is well established, the strength and conditioning practices of high school level players are not well known. Therefore, the purpose of this study was to examine the current strength and conditioning practices that coaches implement at South African high school level rugby. A secondary purpose was to compare practices between different types of schooling systems available in South Africa. An online survey or in person interview (depending on the school), adapted from previous strength and conditioning questionnaires, was conducted with 43 responses; including 28 schools among the top 100 rugby schools in South Africa for 2016 and 15 no-fee paying public schools in the Eastern Cape Province of South Africa. Results indicated that the top 100 rugby schools implement conditioning practices similar to the best-known international practices compared to no-fee paying schools who lacked the knowledge and skills in various strength and conditioning principles. It was found that all no-fee paying school coaches had insufficient qualifications to administer the correct training techniques. Coaches at all schools lacked the appropriate knowledge on injury prevention and scientifically based training programmes. It was concluded that education and skills around the best strength and conditioning practices for school level coaches needs to be improved and particularly in less privileged schools. The main goal being to reduce the risk of injury and improve performance across all sectors of the rugby playing population within the country. This was deemed crucial to the transformation goals set out by the South African Rugby Union, which would benefit from player development in lower socioeconomic schools.
- Full Text:
- Date Issued: 2018
- Authors: Robinson, Bradley Charles
- Date: 2018
- Subjects: Rugby football coaches South Africa , Rugby football Coaching , Rugby football Physiological aspects , Rugby football Training , High school students Social conditions
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63459 , vital:28413
- Description: Although the sport of rugby union is well established, the strength and conditioning practices of high school level players are not well known. Therefore, the purpose of this study was to examine the current strength and conditioning practices that coaches implement at South African high school level rugby. A secondary purpose was to compare practices between different types of schooling systems available in South Africa. An online survey or in person interview (depending on the school), adapted from previous strength and conditioning questionnaires, was conducted with 43 responses; including 28 schools among the top 100 rugby schools in South Africa for 2016 and 15 no-fee paying public schools in the Eastern Cape Province of South Africa. Results indicated that the top 100 rugby schools implement conditioning practices similar to the best-known international practices compared to no-fee paying schools who lacked the knowledge and skills in various strength and conditioning principles. It was found that all no-fee paying school coaches had insufficient qualifications to administer the correct training techniques. Coaches at all schools lacked the appropriate knowledge on injury prevention and scientifically based training programmes. It was concluded that education and skills around the best strength and conditioning practices for school level coaches needs to be improved and particularly in less privileged schools. The main goal being to reduce the risk of injury and improve performance across all sectors of the rugby playing population within the country. This was deemed crucial to the transformation goals set out by the South African Rugby Union, which would benefit from player development in lower socioeconomic schools.
- Full Text:
- Date Issued: 2018
The evaluation of potential dietary media, measurement parameters and storage techniques for use in forensic entomotoxicology
- Mbatha, Erica Isabel Tavares Da Silva
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
- Authors: Mbatha, Erica Isabel Tavares Da Silva
- Date: 2018
- Subjects: Blowflies -- Feeding and feeds , Blowflies -- Larvae , Blowflies -- Physiology , Blowflies -- Collection and preservation , Poisons -- Analysis , Death -- Causes , Forensic pathology , Forensic entomology , Forensic entomotoxicology
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63323 , vital:28393
- Description: The term forensic entomotoxicology was coined by Pounder and is used to describe the process of using insects to determine the presence or absence of toxicants in decomposing corpses. Forensic entomotoxicology is most applicable when the orthodox sources of evidence (i.e. blood and urine) are no longer available for testing due to the degree of putrefaction as a result of the decomposition process. As the field is relatively new, various authors have conducted studies to determine the effects of different toxicants on different insects. These studies have all been conducted in the absence of a standardised protocol and we hypothesise that this has led to conflicting results (i.e. two different authors will conduct a study using the same toxicant and model insect and the effects on the insects will differ significantly). The aim of this thesis was to identify the areas which might have led to the artefacts in the results and identify ways in which to standardise them. The three areas selected were the feeding substrates and the measures taken to quantify growth rate, as well as the preservation techniques that should be used for preserving larval flies. The recommendation from the literature review was that artificial diets would be the most appropriate dietary media to use for entomotoxicological studies. An artificial diet was selected and modified for potential used in entomotoxicological studies. Four different diets (no meat treatment, fish, beef and pork artificial diets) were used to rear Chrysomya chloropyga larvae and their growth rates were measured using length and width. The fly larvae reared on the fish and no meat treatment diets did not reach pupation stage. The beef and pork diets produced the largest larvae and the flies in these treatments reached adult stage. The recommendation was that the beef and pork treatments be tested with various toxicants to establish their stability in the matrix and the diet that provides the toxicants with the most stability should be used for future entomotoxicological studies. The two other factors selected for standardisation were the parameters used to quantify growth rate, as well as the preservation techniques used to store empty Chrysomya chloropyga pupal casings and Calliphora croceipalpis third instar larvae. Previous authors have suggested that width be used as an alternative to length to quantify growth rate. The results from this thesis show that length should continue to be used as the standard parameter because the incremental change in length is much larger than the change in width, and these larger increments allow for greater resolution when estimating the age of the larvae. Various authors have also suggested that pupal casings should be stored without any preservative, whereas fly larvae should be stored in concentrations of ethanol >70%. The results in this thesis have shown that the concentration of ethanol does not make any significant difference to the proportional change of length and width of the empty pupal casings and the third instar larvae. The recommendation is that when selecting the preservation technique, the integrity of the specimen for examination of other evidence (i.e. DNA or toxicological extraction) should take precedence. Although this thesis has not completely standardised the protocol for forensic entomotoxicology, it has indicated the areas that need to be focused on in order for standardisation to occur. Future studies should focus on standardisation, as this makes studies more comparable and ultimately makes entomotoxicological evidence admissible in the court of law.
- Full Text:
- Date Issued: 2018
Biotic and abiotic drivers of macroinvertebrate assemblages in a South African river
- Authors: Bellingan, Terence Andrew
- Date: 2018
- Subjects: Aquatic insects -- South Africa -- Eastern Cape , Stream ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape , Riparian areas -- Management , Ecosystem management -- South Africa -- Eastern Cape , Mayflies -- South Africa -- Eastern Cape , Stoneflies -- South Africa -- Eastern Cape , Keiskamma River
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61839 , vital:28067
- Description: Aquatic insects are the most numerically abundant and diverse group of organisms found in lotic ecosystems in South Africa and the world over. They play vital roles in freshwater ecosystem functioning, processing nutrients and in turn forming integral links in stream food-webs. This thesis focussed on examining the macroinvertebrate fauna within three reaches of headwater streams of the Keiskamma River system: reaches that were considered to be fishless; reaches that were invaded by non-native salmonid species; and reaches that were dominated by native fish. I described the effects of predatory fish presence through detailed examination of macroinvertebrate assemblage composition; macroinvertebrate drift timing and density; and through niche utilisation determined from stable isotope data. Patterns in the macroinvertebrate assemblages of the headwaters of the Keiskamma River appear to be driven more strongly by flow rate and seasonal influences, but fish presence and biotope availability were also significant drivers. Niche shifts due to predator presence were not easy to detect and, while patterns of influence may have been evident, they were not found to be significant. However, I demonstrated that salmonids selectively feed on native fish species when the opportunity is presented, occupying significantly higher trophic levels when co-occurring with native fish than in invaded reaches where native fish are absent. Drift timing and density were demonstrated to be significantly different between reach for specific macroinvertebrate species from the Ephemeroptera and Plecoptera, under differing fish predation regimes, in agreement with what has been observed from studies in rivers elsewhere. In freshwater ecosystems of South Africa and worldwide, mitigation of negative effects of alien fishes through their removal using piscicides may also affect non-target organisms. To better understand the effects of just such a removal operation, employed for the first time in the history of freshwater conservation in South Africa, macroinvertebrate communities were assessed for non-target effects of rotenone. The fish eradication operations were demonstrated to have a short-term negative effect on the macroinvertebrate assemblage, through water quality index measurements and alteration of densities of macroinvertebrate taxa collected from stone surfaces. However, no long-term detrimental impact was observed as macroinvertebrate faunas returned to a comparable pre-treatment state within a year of each rotenone application.
- Full Text:
- Date Issued: 2018
- Authors: Bellingan, Terence Andrew
- Date: 2018
- Subjects: Aquatic insects -- South Africa -- Eastern Cape , Stream ecology -- South Africa -- Eastern Cape , Freshwater ecology -- South Africa -- Eastern Cape , Riparian areas -- Management , Ecosystem management -- South Africa -- Eastern Cape , Mayflies -- South Africa -- Eastern Cape , Stoneflies -- South Africa -- Eastern Cape , Keiskamma River
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61839 , vital:28067
- Description: Aquatic insects are the most numerically abundant and diverse group of organisms found in lotic ecosystems in South Africa and the world over. They play vital roles in freshwater ecosystem functioning, processing nutrients and in turn forming integral links in stream food-webs. This thesis focussed on examining the macroinvertebrate fauna within three reaches of headwater streams of the Keiskamma River system: reaches that were considered to be fishless; reaches that were invaded by non-native salmonid species; and reaches that were dominated by native fish. I described the effects of predatory fish presence through detailed examination of macroinvertebrate assemblage composition; macroinvertebrate drift timing and density; and through niche utilisation determined from stable isotope data. Patterns in the macroinvertebrate assemblages of the headwaters of the Keiskamma River appear to be driven more strongly by flow rate and seasonal influences, but fish presence and biotope availability were also significant drivers. Niche shifts due to predator presence were not easy to detect and, while patterns of influence may have been evident, they were not found to be significant. However, I demonstrated that salmonids selectively feed on native fish species when the opportunity is presented, occupying significantly higher trophic levels when co-occurring with native fish than in invaded reaches where native fish are absent. Drift timing and density were demonstrated to be significantly different between reach for specific macroinvertebrate species from the Ephemeroptera and Plecoptera, under differing fish predation regimes, in agreement with what has been observed from studies in rivers elsewhere. In freshwater ecosystems of South Africa and worldwide, mitigation of negative effects of alien fishes through their removal using piscicides may also affect non-target organisms. To better understand the effects of just such a removal operation, employed for the first time in the history of freshwater conservation in South Africa, macroinvertebrate communities were assessed for non-target effects of rotenone. The fish eradication operations were demonstrated to have a short-term negative effect on the macroinvertebrate assemblage, through water quality index measurements and alteration of densities of macroinvertebrate taxa collected from stone surfaces. However, no long-term detrimental impact was observed as macroinvertebrate faunas returned to a comparable pre-treatment state within a year of each rotenone application.
- Full Text:
- Date Issued: 2018
The impact of leadership on job satisfaction at a specific bank in the Eastern Cape
- Authors: Wyngaard, Shaun Peter
- Date: 2018
- Subjects: Leadership , Bank employees Job satisfaction , Labor turnover , Transformational leadership , Bank management South Africa Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/62050 , vital:28099
- Description: This study aimed at investigating the relationship between leadership and employee job satisfaction in the banking sector of South Africa. The study drew from the fact that there is a growing emphasis in organisations to reduce employee turnover by keeping their employees satisfied. The ultimate performance, effectiveness and competitiveness of an organisation are directly related to an organisation’s ability to keep its employees optimally productive and satisfied. Numerous research studies have been conducted on transformational, transactional and passive-avoidant leadership to determine the significance of their respective relationship with the job satisfaction of employees in different scenarios. Results show that the transformational leadership style has a significant relationship with job satisfaction; while the transactional leadership style or the passive-avoidant style are applied according to changing circumstances. The study adopted a quantitative approach, using online questionnaires as an instrument for collecting primary data. The target population of the study was 380 bank employees, and the target sample was 218; 121 questionnaires were completed and used as the actual final sample. Questionnaires were completed from managers and employees of the selected bank, with the two population groups being investigated using different scales. SPSS was used in analysing the collected data. The findings of this research showed that the leadership styles under investigation have a direct impact on the job satisfaction of employees. Transformational leadership was found to have a significant positive relationship with job satisfaction, while the relationship between transactional leadership and job satisfaction was positive but moderate. A significant negative relationship was found between passive-avoidant leadership and job satisfaction. It is thus the responsibility of the financial institution under investigation to highlight the significant links and benefits of this leadership style to its management to ensure increased job satisfaction and lower turnover of employees in the institution. Literature explored in this study supported the close link between the different leadership styles and job satisfaction.
- Full Text:
- Date Issued: 2018
- Authors: Wyngaard, Shaun Peter
- Date: 2018
- Subjects: Leadership , Bank employees Job satisfaction , Labor turnover , Transformational leadership , Bank management South Africa Eastern Cape
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/62050 , vital:28099
- Description: This study aimed at investigating the relationship between leadership and employee job satisfaction in the banking sector of South Africa. The study drew from the fact that there is a growing emphasis in organisations to reduce employee turnover by keeping their employees satisfied. The ultimate performance, effectiveness and competitiveness of an organisation are directly related to an organisation’s ability to keep its employees optimally productive and satisfied. Numerous research studies have been conducted on transformational, transactional and passive-avoidant leadership to determine the significance of their respective relationship with the job satisfaction of employees in different scenarios. Results show that the transformational leadership style has a significant relationship with job satisfaction; while the transactional leadership style or the passive-avoidant style are applied according to changing circumstances. The study adopted a quantitative approach, using online questionnaires as an instrument for collecting primary data. The target population of the study was 380 bank employees, and the target sample was 218; 121 questionnaires were completed and used as the actual final sample. Questionnaires were completed from managers and employees of the selected bank, with the two population groups being investigated using different scales. SPSS was used in analysing the collected data. The findings of this research showed that the leadership styles under investigation have a direct impact on the job satisfaction of employees. Transformational leadership was found to have a significant positive relationship with job satisfaction, while the relationship between transactional leadership and job satisfaction was positive but moderate. A significant negative relationship was found between passive-avoidant leadership and job satisfaction. It is thus the responsibility of the financial institution under investigation to highlight the significant links and benefits of this leadership style to its management to ensure increased job satisfaction and lower turnover of employees in the institution. Literature explored in this study supported the close link between the different leadership styles and job satisfaction.
- Full Text:
- Date Issued: 2018
Periglacial landforms of the Ahlmannryggen and Jutulsessen areas of western Dronning Maud land, Antarctica
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
- Authors: Wilmot, Nicola Frances
- Date: 2018
- Subjects: Periglacial processes Antarctica Queen Maud Land , Geomorphology Antarctica Queen Maud Land , Permafrost Antarctica Queen Maud Land , Freezes (Meteorology) Antarctica Queen Maud Land , Thawing Antarctica Queen Maud Land
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61535 , vital:28034
- Description: Periglacial landforms are a common occurrence in Ahlmannryggen and Jutulsessen areas of western Dronning Maud land (WDML). Classification and formation of these landforms were disputed in literature. In Antarctica information on periglacial landforms is limited or confined to a specific landform. Thus a holistic approach was taken when investigating the periglacial landforms found in WDML. An overview of the existing knowledge base on periglacial landforms in WDML was given which was coupled with the analysis of archival data. The landforms found in this area were patterned ground, openwork block deposits (OBD), rock glaciers, terraces, a pronival rampart and lake ice blisters. With patterned ground being the common periglacial landform in WDML, heave monitoring was used where time-lapse videos were used to investigate the formation processes in patterned ground. From consolidating existing knowledge as well as adding new knowledge on the formation of periglacial landforms, it is clear that the landforms in Antarctica should not be compared to other examples, especially examples from the northern hemisphere. Further research in the formation of periglacial landforms is needed and can be further enhanced with more extensive use of the heave monitoring method in future research.
- Full Text:
- Date Issued: 2018
The role of African languages in the South African legal system: towards a transformative agenda
- Authors: Docrat, Zakeera
- Date: 2018
- Subjects: Forensic linguistics -- South Africa , Communication in law -- South Africa , Language policy -- South Africa , Linguistic rights -- South Africa , Court interpreting and translating -- South Africa , African languages -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/60809 , vital:27833
- Description: This interdisciplinary thesis, partly located in the emerging discipline of forensic linguistics, seeks to investigate the status and use of African languages in the South African legal system and how language can be used as a tool to transform the legal system. The research commences with an overview of the development of African languages in the legal system, pre and post Apartheid. The research proceeds to an overview of scholarly literature concerning the role of legislation, language policy and planning in regulating the use of African languages in the legal system, in order to give effect to South Africa’s constitutional provisions and enable linguistic transformation of the legal system. This research furthermore provides a critique of the constitutional language framework in relation to language rights of litigants in the legal system, when accessing justice through the medium of an African language. To this effect the research advances cases conducted in their entirety in an African language, illustrating that it is both possible and practicable. This research engages critically with the legislative and policy frameworks of the legal system, where issues concerning the equal recognition and use of African languages are highlighted. Language demographics in the form of statistics are provided, illustrative of the fact that the majority of South African’s speak an African language as their mother tongue. Additionally, the statistics provide that litigants in the legal system have poor proficiency in English, the language of record in courts. The research addresses the legislative and policy deficiencies of the non insertion of language requirements for legal practitioners and judicial officers that reflect the language demographics. Furthermore the need for linguistically competent legal practitioners and judicial officers is discussed in giving meaning to the constitutional language rights of litigants. A Canadian comparative jurisprudential case study is advanced, that can be emulated by the South African legal system. The Canadian model offers a precise and effective constitutional, legislative and policy framework where language rights are purposively interpreted in cases conducted in the official languages of the country. Furthermore the Canadian model provides that legal practitioners and judicial officers are linguistically competent in the official languages of the province in which they practice. This thesis highlights the issues hindering real transformation of the legal system, and concludes with recommendations which are both legally and linguistically sound.
- Full Text:
- Date Issued: 2018
- Authors: Docrat, Zakeera
- Date: 2018
- Subjects: Forensic linguistics -- South Africa , Communication in law -- South Africa , Language policy -- South Africa , Linguistic rights -- South Africa , Court interpreting and translating -- South Africa , African languages -- South Africa
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/60809 , vital:27833
- Description: This interdisciplinary thesis, partly located in the emerging discipline of forensic linguistics, seeks to investigate the status and use of African languages in the South African legal system and how language can be used as a tool to transform the legal system. The research commences with an overview of the development of African languages in the legal system, pre and post Apartheid. The research proceeds to an overview of scholarly literature concerning the role of legislation, language policy and planning in regulating the use of African languages in the legal system, in order to give effect to South Africa’s constitutional provisions and enable linguistic transformation of the legal system. This research furthermore provides a critique of the constitutional language framework in relation to language rights of litigants in the legal system, when accessing justice through the medium of an African language. To this effect the research advances cases conducted in their entirety in an African language, illustrating that it is both possible and practicable. This research engages critically with the legislative and policy frameworks of the legal system, where issues concerning the equal recognition and use of African languages are highlighted. Language demographics in the form of statistics are provided, illustrative of the fact that the majority of South African’s speak an African language as their mother tongue. Additionally, the statistics provide that litigants in the legal system have poor proficiency in English, the language of record in courts. The research addresses the legislative and policy deficiencies of the non insertion of language requirements for legal practitioners and judicial officers that reflect the language demographics. Furthermore the need for linguistically competent legal practitioners and judicial officers is discussed in giving meaning to the constitutional language rights of litigants. A Canadian comparative jurisprudential case study is advanced, that can be emulated by the South African legal system. The Canadian model offers a precise and effective constitutional, legislative and policy framework where language rights are purposively interpreted in cases conducted in the official languages of the country. Furthermore the Canadian model provides that legal practitioners and judicial officers are linguistically competent in the official languages of the province in which they practice. This thesis highlights the issues hindering real transformation of the legal system, and concludes with recommendations which are both legally and linguistically sound.
- Full Text:
- Date Issued: 2018
Influence of knowledge of the end-point on pacing during a 2000m rowing time trial
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
- Authors: Ferreira, Dean
- Date: 2018
- Subjects: Rowing -- Training , Rowing -- Coaching , Endurance sports -- Training , Rowers -- Ability testing , Rowing -- Training -- Psychological aspects
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/61636 , vital:28044
- Description: Introduction: A typical 2000 m rowing race requires maximal force production over six to eight minutes. Optimal distribution of energetic resources during such a race is vital for optimal performance. There is little research examining the pacing strategies employed by rowers, particularly at the sub-elite level. Aim: The purpose of this investigation was to determine the influence of knowledge of the end-point on pacing during a 2000 m rowing time trial. Methods: Eleven male rowers from a university rowing club volunteered to partake in the study. Each participant completed three experimental trials on an indoor rowing ergometer, each 2000 m. The only difference between the trials was the nature of the information provided beforehand. At the start of the control trial, participants were correctly informed about the distance to be covered. Participants were not informed of the distance to be completed in the unknown trial. For the deceptive trial, participants were told 1000 m would be completed, but when this distance was reached, they were told to continue for another 1000 m. During each trial muscle activity, power output, heart rate, performance time and perceptions of effort were measured.Results: The control trial was significantly (p<0.05) faster than both the unknown and deceptive trials, however the deceptive trial was the fastest of all trials at the 1000 m distance. The unknown trial was slowest at 1000 m and at 2000 m. Muscle activity, RPE, heart rate and power output were significantly (p<0.05) lower in the unknown trial compared to the control and deceptive trial. The control trial exhibited a reverse J-shape pacing profile. The deceptive trial revealed a significant (p<0.05) reduction in performance time, heart rate, power output and muscle activity after the 1000 m interval. The first 500 m interval had the fastest performance and highest power output in all trials. In all trials, RPE was highest at the end of the 2000 m, the greatest reading being obtained at the end of the control trial. During the first 1000 m of the deceptive trial, the dependant variables were similar to those in the control trial. Once the deception was revealed, there was a significant (p<0.05) reduction in the muscle activity, heart rate and power output. Conclusion: The results of this study indicate that accurate end-point information is crucial to the development of an optimal pacing strategy, and ultimately to successful performance. Rowers tend to adopt the reverse J-shape pacing profile most often due to the tactical and physiological benefits offered by this strategy. Unknown or inaccurate end-point information resulted in performance decrements due to the uncertainty associated with the exercise bout.
- Full Text:
- Date Issued: 2018
Modelling Ionospheric vertical drifts over the African low latitude region
- Dubazane, Makhosonke Berthwell
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
- Date Issued: 2018
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
- Date Issued: 2018
A psychobiographical study of Temple Grandin
- Authors: Wannenburg, Nicola
- Date: 2018
- Subjects: Grandin, Temple , Psychology Biographical methods , Psychoanalysis , Autistic women United States Biography , Women animal specialists United States Biography , Developmental psychology , Erikson, Erik H (Erik Homburger), 1902-1994
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57358 , vital:26877
- Description: Psychobiographical researchers methodically formulate life histories and interpret them by means of psychological theories. The research typically focuses on exemplary and completed lives. The cases that are studied are usually of individuals who are of particular interest to society as a result of excelling in their particular fields, be they to benefit or detriment of society. Temple Grandin was chosen for this study using purposive sampling as she meets the psychobiographical requirement of being an extraordinary individual. As an individual with autism Grandin faced many challenges growing up. Despite a difficult and absent beginning, Grandin developed into a stable and scientifically creative adult who contributes to society. She excels as an animal scientist and designer of humane livestock handling facilities and has an international reputation for her contribution to the livestock industry and animal welfare. The primary aim of this study is to describe and interpret the life of Temple Grandin through Erikson’s (1950/1973) theory of psychosocial development. A mixed method approach (Yin, 2006) was employed for the conduction of this study. The overarching data processing and analysis guidelines for this study were provided by Miles and Huberman (1994, 2002a, 2002b). The conduction of the processing and analysis of data was aided by Alexander’s (1988, 1990) method of asking the data questions as well as an integration of Yin’s (2014) time series analysis with Erikson’s (1950/1973) triple bookkeeping approach. This study contributes to the development of psychobiographical research in South Africa as well as to personality and developmental theory.
- Full Text:
- Date Issued: 2018
- Authors: Wannenburg, Nicola
- Date: 2018
- Subjects: Grandin, Temple , Psychology Biographical methods , Psychoanalysis , Autistic women United States Biography , Women animal specialists United States Biography , Developmental psychology , Erikson, Erik H (Erik Homburger), 1902-1994
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57358 , vital:26877
- Description: Psychobiographical researchers methodically formulate life histories and interpret them by means of psychological theories. The research typically focuses on exemplary and completed lives. The cases that are studied are usually of individuals who are of particular interest to society as a result of excelling in their particular fields, be they to benefit or detriment of society. Temple Grandin was chosen for this study using purposive sampling as she meets the psychobiographical requirement of being an extraordinary individual. As an individual with autism Grandin faced many challenges growing up. Despite a difficult and absent beginning, Grandin developed into a stable and scientifically creative adult who contributes to society. She excels as an animal scientist and designer of humane livestock handling facilities and has an international reputation for her contribution to the livestock industry and animal welfare. The primary aim of this study is to describe and interpret the life of Temple Grandin through Erikson’s (1950/1973) theory of psychosocial development. A mixed method approach (Yin, 2006) was employed for the conduction of this study. The overarching data processing and analysis guidelines for this study were provided by Miles and Huberman (1994, 2002a, 2002b). The conduction of the processing and analysis of data was aided by Alexander’s (1988, 1990) method of asking the data questions as well as an integration of Yin’s (2014) time series analysis with Erikson’s (1950/1973) triple bookkeeping approach. This study contributes to the development of psychobiographical research in South Africa as well as to personality and developmental theory.
- Full Text:
- Date Issued: 2018
Discovery and validation of a CD4 binding aptamer through Crossover SELEX towards the preliminary development of a point-of-care aptasensor for rapid CD4+ T-cell counting
- Authors: Fellows, Tamika
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63527 , vital:28431
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
- Authors: Fellows, Tamika
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/63527 , vital:28431
- Description: Expected release date-April 2020
- Full Text:
- Date Issued: 2018
Behaviour of quiet time ionospheric disturbances at African equatorial and midlatitude regions
- Authors: Orford, Nicola Diane
- Date: 2018
- Subjects: Ionospheric storms , Ionospheric storms -- Africa , Ionosphere , Plasmasphere , Q-disturbances , Total electron content (TEC)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62672 , vital:28228
- Description: Extreme ionospheric and geomagnetic disturbances affect technology adversely. Prestorm enhancements, considered a potential predictor of geomagnetic storms, occur during quiet conditions prior to geomagnetic disturbances. The ionosphere experiences general disturbances during quiet geomagnetic conditions and these Q- disturbances remain unexplored over Africa. This study used TEC data to characterize the morphology of Q-disturbances over Africa, exploring variations with solar cycle, season, time of occurrence and latitude. Observations from 10 African GPS stations in the equatorial and midlatitude regions show that Q-disturbances in the equatorial region are predominantly driven by E x B variations, while multiple mechanisms affect the midlatitude region. Q- disturbances occur more frequently during nighttime than during daytime and no seasonal trend is observed. Midlatitude Q-disturbance mechanisms are explored in depth, considering substorm activity, the plasmaspheric contribution to GPS TEC and plasma transfer between conjugate points. Substorm activity is not a dominant mechanism, although Q-disturbances occurring under elevated substorm conditions tend to have longer duration and larger amplitude than general Q-disturbances. Many observed Q-disturbances become non-significant once the plasmaspheric contribution to the TEC measurements is removed, indicating that these disturbances occur within the plasmasphere, and not the ionosphere. Transfer of plasma between conjugate points does not seem to be a mechanism driving Q-disturbances, as the corresponding nighttime behaviour expected between depletions in the summer hemisphere and enhancements in the winter hemisphere is not observed. Pre-storm enhancements occur infrequently, rendering them a poor predictor of geomagnetic disturbances. Pre-storm enhancement morphology does not differ significantly from general quiet time enhancement morphology, suggesting pre-storms are not a special case of Q-disturbances.
- Full Text:
- Date Issued: 2018
- Authors: Orford, Nicola Diane
- Date: 2018
- Subjects: Ionospheric storms , Ionospheric storms -- Africa , Ionosphere , Plasmasphere , Q-disturbances , Total electron content (TEC)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62672 , vital:28228
- Description: Extreme ionospheric and geomagnetic disturbances affect technology adversely. Prestorm enhancements, considered a potential predictor of geomagnetic storms, occur during quiet conditions prior to geomagnetic disturbances. The ionosphere experiences general disturbances during quiet geomagnetic conditions and these Q- disturbances remain unexplored over Africa. This study used TEC data to characterize the morphology of Q-disturbances over Africa, exploring variations with solar cycle, season, time of occurrence and latitude. Observations from 10 African GPS stations in the equatorial and midlatitude regions show that Q-disturbances in the equatorial region are predominantly driven by E x B variations, while multiple mechanisms affect the midlatitude region. Q- disturbances occur more frequently during nighttime than during daytime and no seasonal trend is observed. Midlatitude Q-disturbance mechanisms are explored in depth, considering substorm activity, the plasmaspheric contribution to GPS TEC and plasma transfer between conjugate points. Substorm activity is not a dominant mechanism, although Q-disturbances occurring under elevated substorm conditions tend to have longer duration and larger amplitude than general Q-disturbances. Many observed Q-disturbances become non-significant once the plasmaspheric contribution to the TEC measurements is removed, indicating that these disturbances occur within the plasmasphere, and not the ionosphere. Transfer of plasma between conjugate points does not seem to be a mechanism driving Q-disturbances, as the corresponding nighttime behaviour expected between depletions in the summer hemisphere and enhancements in the winter hemisphere is not observed. Pre-storm enhancements occur infrequently, rendering them a poor predictor of geomagnetic disturbances. Pre-storm enhancement morphology does not differ significantly from general quiet time enhancement morphology, suggesting pre-storms are not a special case of Q-disturbances.
- Full Text:
- Date Issued: 2018
Developing leadership and learner voice: a formative intervention in a Learner Representative Council in a Namibian secondary school
- Authors: Haipa, Vistorina
- Date: 2018
- Subjects: School management and organization -- Namibia , Educational leadership -- Namibia , Education, Secondary -- Namibia , Student government -- Namibia , Student participation in administration -- Namibia , Student participation in administration -- Law and legislation -- Namibia , Cultural Historical Activity Theory
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62188 , vital:28136
- Description: Learner participation in leadership in Namibian schools was legislated in 2001 through the Namibian Education Act, No. 16 of 2001. This has then become a requirement for all secondary schools to establish a Learner Representative Council (LRC). However, this legislation only gives mandates to schools with grade 8-12. Despite the impetus of having a LRC in secondary schools, learner leadership and voice remains limited, given that we are 26 years into our democracy. This awakened my interest to conduct a study aimed at developing leadership and voice within the LRC in a Namibian secondary school. Additionally, this study was conducted to contribute to filling the gap in literature of Cultural Historical Activity Theory (CHAT) studies in the field of Education Leadership and Management. In this critical case orientation, the LRC were the subjects and the object of the activity was voice and leadership development within the LRC. I investigated participants’ perspectives on LRC leadership opportunities that existed in the case study school as well as factors that enabled and constrained leadership and voice development within the LRC of Omukumo (pseudonym) Secondary School in the northern part of Namibia. My study adopted a formative intervention design, using qualitative methodologies such as document analysis, observation, interviews, questionnaires and Change Laboratory Workshops. This study was framed by the second generation of CHAT. CHAT in this study was used as a methodological and analytical tool to surface the contradictions. Additionally, data were analysed by means of constructing categories and themes. Five sets of findings emerged: (1) a lack of conceptual awareness of the construct ‘learner leadership’: learner leadership was understood in terms of the LRC, (2) LRC members were not really acknowledged as equal participants in the school decision-making due to unequal power relations between the teachers and the LRC members, (3) misinterpretation of LRC policy that speak about the establishment of learners club and inadequate LRC training hindered the development of voice and leadership within the LRC, (4) the overall leadership role assigned to the LRC was to oversee the adherence of the school rules, and last (5) learner leadership and voice was still developing in the case study school. My key recommendation based on the research findings is the need for on-going LRC training at regional level; a need for large scale comparative studies between two African countries (Namibia, & South Africa) on the topic of learner leadership development and last, a need for workshops to train teachers on the implementation of national policies in schools, in particular those that speak to issues of learner voice and leadership.
- Full Text:
- Date Issued: 2018
- Authors: Haipa, Vistorina
- Date: 2018
- Subjects: School management and organization -- Namibia , Educational leadership -- Namibia , Education, Secondary -- Namibia , Student government -- Namibia , Student participation in administration -- Namibia , Student participation in administration -- Law and legislation -- Namibia , Cultural Historical Activity Theory
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/62188 , vital:28136
- Description: Learner participation in leadership in Namibian schools was legislated in 2001 through the Namibian Education Act, No. 16 of 2001. This has then become a requirement for all secondary schools to establish a Learner Representative Council (LRC). However, this legislation only gives mandates to schools with grade 8-12. Despite the impetus of having a LRC in secondary schools, learner leadership and voice remains limited, given that we are 26 years into our democracy. This awakened my interest to conduct a study aimed at developing leadership and voice within the LRC in a Namibian secondary school. Additionally, this study was conducted to contribute to filling the gap in literature of Cultural Historical Activity Theory (CHAT) studies in the field of Education Leadership and Management. In this critical case orientation, the LRC were the subjects and the object of the activity was voice and leadership development within the LRC. I investigated participants’ perspectives on LRC leadership opportunities that existed in the case study school as well as factors that enabled and constrained leadership and voice development within the LRC of Omukumo (pseudonym) Secondary School in the northern part of Namibia. My study adopted a formative intervention design, using qualitative methodologies such as document analysis, observation, interviews, questionnaires and Change Laboratory Workshops. This study was framed by the second generation of CHAT. CHAT in this study was used as a methodological and analytical tool to surface the contradictions. Additionally, data were analysed by means of constructing categories and themes. Five sets of findings emerged: (1) a lack of conceptual awareness of the construct ‘learner leadership’: learner leadership was understood in terms of the LRC, (2) LRC members were not really acknowledged as equal participants in the school decision-making due to unequal power relations between the teachers and the LRC members, (3) misinterpretation of LRC policy that speak about the establishment of learners club and inadequate LRC training hindered the development of voice and leadership within the LRC, (4) the overall leadership role assigned to the LRC was to oversee the adherence of the school rules, and last (5) learner leadership and voice was still developing in the case study school. My key recommendation based on the research findings is the need for on-going LRC training at regional level; a need for large scale comparative studies between two African countries (Namibia, & South Africa) on the topic of learner leadership development and last, a need for workshops to train teachers on the implementation of national policies in schools, in particular those that speak to issues of learner voice and leadership.
- Full Text:
- Date Issued: 2018