Nature conservation, protected areas and local communities : the Tsitsikamma National Park
- Authors: Le Fleur, Yvette Adele
- Date: 2021-04
- Subjects: National parks and reserves -- South Africa -- Eastern Cape , Protected areas -- Management , Programme of Work on Protected Areas , Human ecology -- South Africa -- Tsitsikamma , Nature conservation -- Citizen participation
- Language: English
- Type: thesis , text , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/177247 , vital:42803
- Description: Since the twentieth century, protected areas, usually in the form of nature reserves or national parks, have become increasingly more dominant as an international conservation strategy. An important factor in protected area management is the relationship between protected areas and its surrounding communities. Historically, the fortress conservation model based on the exclusion of human use and occupation prevailed in relation to protected areas. It is known that this approach brought with it many social and environmental injustices to local communities living in or adjacent to parks. However, a shift in conservation thinking occurred towards the end of the twentieth century, where it has increasingly been advocated for a more participatory approach in protected area management. South Africa has signed the international Convention on Biological Diversity that promotes a participatory approach to nature conservation, which is also reflected in the country’s national laws and policies. In relation to the literature and the lens of political ecology, this thesis sets out to assess in what ways and to what extent the participatory approach has been embraced by South Africa’s conservation authorities. As a case study, it looks at the Tsitsikamma National P ark ( incorporated into the larger Garden Route National Park). In order to get insight on h ow the participatory approach plays itself out at the T NP and what the nature of local communities’ relationship with the park is, this study looks at the aspects of (1) local communities’ socio-economic conditions, (2) their relationship with their natural environment, (3) their perception of nature conservation and (4) their perception of tourism. Then, taking all these aspects into account, (5) how local communities, in general, perceive their relationship with the p ark and its authorities. This study looked at the communities of Kurland, Nature’s Valley, Covie and Storms River. It shows in concurrence with other studies, that despite progressive laws and policies that express the intention of the South African state and SANParks to embrace the participatory approach, its implementation o n t he g round is riddled with challenges. , Thesis (MSocSc) -- Faculty of Humanities, Athropology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Le Fleur, Yvette Adele
- Date: 2021-04
- Subjects: National parks and reserves -- South Africa -- Eastern Cape , Protected areas -- Management , Programme of Work on Protected Areas , Human ecology -- South Africa -- Tsitsikamma , Nature conservation -- Citizen participation
- Language: English
- Type: thesis , text , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/177247 , vital:42803
- Description: Since the twentieth century, protected areas, usually in the form of nature reserves or national parks, have become increasingly more dominant as an international conservation strategy. An important factor in protected area management is the relationship between protected areas and its surrounding communities. Historically, the fortress conservation model based on the exclusion of human use and occupation prevailed in relation to protected areas. It is known that this approach brought with it many social and environmental injustices to local communities living in or adjacent to parks. However, a shift in conservation thinking occurred towards the end of the twentieth century, where it has increasingly been advocated for a more participatory approach in protected area management. South Africa has signed the international Convention on Biological Diversity that promotes a participatory approach to nature conservation, which is also reflected in the country’s national laws and policies. In relation to the literature and the lens of political ecology, this thesis sets out to assess in what ways and to what extent the participatory approach has been embraced by South Africa’s conservation authorities. As a case study, it looks at the Tsitsikamma National P ark ( incorporated into the larger Garden Route National Park). In order to get insight on h ow the participatory approach plays itself out at the T NP and what the nature of local communities’ relationship with the park is, this study looks at the aspects of (1) local communities’ socio-economic conditions, (2) their relationship with their natural environment, (3) their perception of nature conservation and (4) their perception of tourism. Then, taking all these aspects into account, (5) how local communities, in general, perceive their relationship with the p ark and its authorities. This study looked at the communities of Kurland, Nature’s Valley, Covie and Storms River. It shows in concurrence with other studies, that despite progressive laws and policies that express the intention of the South African state and SANParks to embrace the participatory approach, its implementation o n t he g round is riddled with challenges. , Thesis (MSocSc) -- Faculty of Humanities, Athropology, 2021
- Full Text:
- Date Issued: 2021-04
An investigation of support services available for black female owners of bed & breakfasts in Makhanda
- Authors: Mdluli, Lukhona Silubonile
- Date: 2021-04
- Subjects: Bed and breakfast accommodations -- South Africa -- Makhanda , Businesspeople, Black -- South Africa -- Makhanda , Business enterprises, Black -- South Africa -- Makhanda , Women-owned business enterprises -- South Africa -- Makhanda , Government aid to small business -- South Africa , Small business -- South Africa -- Makhanda , Racism -- South Africa -- Makhanda , Businesswomen -- South Africa -- Makhanda
- Language: English
- Type: thesis , text , Masters , MBA
- Identifier: http://hdl.handle.net/10962/177181 , vital:42797
- Description: Over the last 26 years, the South African government has committed to SMME development. To do this, policies and support institutions were put in place which would create a favourable environment for SMME development. This was particularly important as after 1994, when the South African economy was re-integrated into global markets after years of having sanctions imposed against the country as a result of the apartheid system. The tourism industry was identified as one of the key economic drivers which would strengthen the economy and assist in job creation, especially since South Africa would be able to attract international tourists. Further, it created the opportunity for new participants to enter the industry, including black entrepreneurs who previously could not enter the industry as a result of the apartheid laws. The opening up of the country to international markets and the focus on the tourism industry also presented the opportunity for new forms of tourism to be explored including township tourism, which gave rise to the black-owned bed & breakfast sector. Over time, it has become evident that black entrepreneurs in this sector are facing a number of challenges, in spite of the pro-SMME policies and support institutions that are in place. Because this study seeks to investigate the support services available for black female bed & breakfast owners in Makhanda, a qualitative research approach using the interpretative theoretical framework was applied. By using semi-structured interview questions, to establish what challenges do black female bed and breakfast owners face the researcher was able to respond to the following; what participants identify as their needs; and whether they are able to access the support services that are made available by the Government. Results indicated that the majority of entrepreneurs have difficulty accessing funding to develop their businesses. The seasonality of Grahamstown/ Makhanda tourism businesses has its pros and cons for tourism entrepreneurs. Despite efforts by government to transform the tourism industry, black female entrepreneurs in this industry still experience a myriad of challenges, including passive racism. Insufficient institutional support and inaccessible support services for women have made it difficult to manage in this this environment. Thus, a recommendation is put forward for female focused entrepreneurship policy, which is more responsive in terms of a judicial and legal system(s) aimed at addressing women’s particular needs and challenges. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mdluli, Lukhona Silubonile
- Date: 2021-04
- Subjects: Bed and breakfast accommodations -- South Africa -- Makhanda , Businesspeople, Black -- South Africa -- Makhanda , Business enterprises, Black -- South Africa -- Makhanda , Women-owned business enterprises -- South Africa -- Makhanda , Government aid to small business -- South Africa , Small business -- South Africa -- Makhanda , Racism -- South Africa -- Makhanda , Businesswomen -- South Africa -- Makhanda
- Language: English
- Type: thesis , text , Masters , MBA
- Identifier: http://hdl.handle.net/10962/177181 , vital:42797
- Description: Over the last 26 years, the South African government has committed to SMME development. To do this, policies and support institutions were put in place which would create a favourable environment for SMME development. This was particularly important as after 1994, when the South African economy was re-integrated into global markets after years of having sanctions imposed against the country as a result of the apartheid system. The tourism industry was identified as one of the key economic drivers which would strengthen the economy and assist in job creation, especially since South Africa would be able to attract international tourists. Further, it created the opportunity for new participants to enter the industry, including black entrepreneurs who previously could not enter the industry as a result of the apartheid laws. The opening up of the country to international markets and the focus on the tourism industry also presented the opportunity for new forms of tourism to be explored including township tourism, which gave rise to the black-owned bed & breakfast sector. Over time, it has become evident that black entrepreneurs in this sector are facing a number of challenges, in spite of the pro-SMME policies and support institutions that are in place. Because this study seeks to investigate the support services available for black female bed & breakfast owners in Makhanda, a qualitative research approach using the interpretative theoretical framework was applied. By using semi-structured interview questions, to establish what challenges do black female bed and breakfast owners face the researcher was able to respond to the following; what participants identify as their needs; and whether they are able to access the support services that are made available by the Government. Results indicated that the majority of entrepreneurs have difficulty accessing funding to develop their businesses. The seasonality of Grahamstown/ Makhanda tourism businesses has its pros and cons for tourism entrepreneurs. Despite efforts by government to transform the tourism industry, black female entrepreneurs in this industry still experience a myriad of challenges, including passive racism. Insufficient institutional support and inaccessible support services for women have made it difficult to manage in this this environment. Thus, a recommendation is put forward for female focused entrepreneurship policy, which is more responsive in terms of a judicial and legal system(s) aimed at addressing women’s particular needs and challenges. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2021
- Full Text:
- Date Issued: 2021-04
Livelihood implications of a possible Ramsar declaration of the Swartkops estuary, Eastern Cape, South Africa
- Authors: Vembo, Glen Muchengeti
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164715 , vital:41157
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Environmental Science, 2020
- Full Text:
- Date Issued: 2020
- Authors: Vembo, Glen Muchengeti
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/164715 , vital:41157
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Environmental Science, 2020
- Full Text:
- Date Issued: 2020
A Systematic Visualisation Framework for Radio-Imaging Pipelines
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Andati, Lexy Acherwa Livoyi
- Date: 2021-04
- Subjects: Radio interferometers , Radio astronomy -- Data processing , Radio astronomy -- Data processing -- Software , Jupyter
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177338 , vital:42812
- Description: Pipelines for calibration and imaging of radio interferometric data produce many intermediate images and other data products (gain tables, etc.) These often contain valuable information about the quality of the data and the calibration, and can provide the user with valuable insights, if only visualised in the right way. However, the deluge of data that we’re experiencing with modern instruments means that most of these products are never looked at, and only the final images and data products are examined. Furthermore, the variety of imaging algorithms currently available, and the range of their options, means that very different results can be produced from the same set of original data. Proper understanding of this requires a systematic comparison that can be carried out both by individual users locally, and by the community globally. We address both problems by developing a systematic visualisation framework based around Jupyter notebooks, enriched with interactive plots based on the Bokeh and Datashader visualisation libraries. , Thesis (MSc) -- Faculty of Science, Department of Physics and Electronics, 2021
- Full Text:
- Date Issued: 2021-04
Observations of cosmic re-ionisation with the Hydrogen Epoch of Reionization Array: simulations of closure phase spectra
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04
- Authors: Charles, Ntsikelelo
- Date: 2021-04
- Subjects: Epoch of reionization , Space interferometry , Astronomy -- Observations , Closure phase spectra
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/174470 , vital:42480
- Description: The 21 cm transition from neutral Hydrogen promises to be the best observational probe of the Epoch of Reionisation. It has driven the construction of the new generation of low frequency radio interferometric arrays, including the Hydrogen Epoch of Reionization Array (HERA). The main difficulty in measuring the 21 cm signal is the presence of bright foregrounds that require very accurate interferometric calibration. Thyagarajan et al. (2018) proposed the use of closure phase quantities as a means to detect the 21 cm signal, which has the advantage of being independent (to first order) from calibration errors and therefore, bypasses the need for accurate calibration. Closure phases are, however, affected by so-called direction dependent effects, e.g. the fact that the dishes - or antennas - of an interferometric array are not identical to each other and , therefore, yield different antenna primary beam responses. In this thesis, we investigate the impact of direction dependent effects on closure quantities and simulate the impact that primary antenna beams affected by mutual coupling have on the foreground closure phase and its power spectrum i.e. the power spectrum of the bispectrum phase (Thyagarajan et al., 2020). Our simulations show that primary beams affected by mutual coupling lead to an overall leakage of foreground power in the so-called EoR window, i.e. power from smooth-spectrum foregrounds is confined to low k modes. We quantified this effect and found that the leakage is up to ~ 8 orders magnitude higher than the case of an ideal beam at kǁ > 0:5 h Mpc-1. We also found that the foreground leakage is worse when edge antennas are included, as they have a more different primary beam compared to antennas at the centre of the array. The leakage magnitude is worse when bright foregrounds appear in the antenna sidelobes, as expected. Our simulations provide a useful framework to interpret observations and assess which power spectrum region is expected to be most contaminated by foreground power leakage.
- Full Text:
- Date Issued: 2021-04
An assessment of the wild cyclopia subternata (vleitee) resource
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Van der Walt, Wouter
- Date: 2021-04
- Subjects: Legumes -- South Africa , Fynbos -- South Africa , Fynbos ecology -- South Africa , Fynbos -- Harvesting -- South Africa , Biodiversity conservation -- South Africa , Traditional ecological knowledge -- South Africa , Wild Cyclopia Subternata (Vleitee) , Honeybush tea industry
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176874 , vital:42767
- Description: Cyclopia spp. is used for the production of Honeybush tea, an herbal tea which is used in many cases as a substitute for rooibos tea. The wild harvesting of this fynbos plant still brings in up to 85% of the annual crop and as such needs to be carefully monitored in order to avoid over harvesting and the destruction of biodiversity within the Eastern and Western Cape mountain regions of Southern Africa. Due to the concerns of overharvesting and unsuitable use of the wild resource issues of supply security have been raised. There is a lack of formal knowledge relating to the plant, its harvesting, the industry and its economic potential. This study aimed to amend this scarcity by contributing to the knowledge of C. subternata as a wild harvested plant, the physical environment favoured by C. subternata, sustainable use through harvesting of the wild plant and harvesting methods specific to this honeybush species. The research concludes by presenting a guideline for best harvest practices of the wild C. subternata plant. , Thesis (MSc) -- Faculty of Science, Department of Geography, 2021
- Full Text:
- Date Issued: 2021-04
Creating shared value through innovating business models: a case study of the Mapela Water Project
- Authors: Moyo, Bonnie
- Date: 2021-04
- Subjects: Business planning -- South Africa , Strategic planning -- South Africa , Sustainable development -- South Africa , Social responsibility of business -- South Africa , Mineral industries -- South Africa , Mapela Water Project , Hourglass Model
- Language: English
- Type: thesis , text , Masters , MBA
- Identifier: http://hdl.handle.net/10962/177135 , vital:42793
- Description: Shared value creation is a contemporary concept that aims to address the strained relationship between business and society through business models that expand the competitive advantage of business while addressing societal challenges in the business environment. Being a novel concept, studies on how value is created and shared are limited, especially where the unit of analysis is a specific project. This paper investigates how value is created and shared among stakeholders using a water project case study reported as a shared value initiative. The investigation is considered under the Hourglass Model (Ludeke-Freund, Massa, Bocken, Brent and Musango, 2016) as a guiding framework. This sustainable business model is suggested as a business model that creates shared value. The study uses a qualitative research approach to investigate the inputs into the Hourglass Model (Ludeke-Freund et al., 2016) in the form of capitals, briefly considers the business models of specific stakeholders and then analyses the value created, missed and destroyed for each stakeholder through their value creation mechanisms. In the findings, six different capitals are identified from the participating stakeholders, and the value created, destroyed, and missed is discussed in the context of shared value principles. The findings show that capitals are used as inputs into the Hourglass Model and are consumed, created, and regenerated. There is also the realisation from the findings that different stakeholders required different and varying amounts of the six capitals identified. The interconnectedness of the capitals is shown in the study, and the findings show that the context of the environment within which a project operates contributes to the creation of shared value. As with the six capitals, the findings show that multiple stakeholders create shared value confirming stakeholder theory's guiding principles regarding stakeholder salience, which are relevant for creating shared value. Some stakeholders are identified as being more important to creating shared value in the project than others. Trade-offs are then required for value creation from a finite pool of capitals and stakeholders to consider the capitals and stakeholders' long and short-term impacts. Identifying stakeholders and the capitals allowed the researcher to consider the value created, destroyed and missed in the project. This assessment of shared value generated forms part of the findings on business models' outcomes for shared value, summarised for the project. Based on these areas where the outcomes are missing or destroying value, recommendations are made to address these opportunities, and an area of further research is identified. Drawing on these outcomes, developing clusters as per the value creation avenues of shared value would be the most appropriate avenue for this project. The study adds to the shared value body of knowledge by operationalising the Hourglass Model (Ludeke-Freund et al., 2016) and illustrating how the Model can be used to consider shared value creation. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Moyo, Bonnie
- Date: 2021-04
- Subjects: Business planning -- South Africa , Strategic planning -- South Africa , Sustainable development -- South Africa , Social responsibility of business -- South Africa , Mineral industries -- South Africa , Mapela Water Project , Hourglass Model
- Language: English
- Type: thesis , text , Masters , MBA
- Identifier: http://hdl.handle.net/10962/177135 , vital:42793
- Description: Shared value creation is a contemporary concept that aims to address the strained relationship between business and society through business models that expand the competitive advantage of business while addressing societal challenges in the business environment. Being a novel concept, studies on how value is created and shared are limited, especially where the unit of analysis is a specific project. This paper investigates how value is created and shared among stakeholders using a water project case study reported as a shared value initiative. The investigation is considered under the Hourglass Model (Ludeke-Freund, Massa, Bocken, Brent and Musango, 2016) as a guiding framework. This sustainable business model is suggested as a business model that creates shared value. The study uses a qualitative research approach to investigate the inputs into the Hourglass Model (Ludeke-Freund et al., 2016) in the form of capitals, briefly considers the business models of specific stakeholders and then analyses the value created, missed and destroyed for each stakeholder through their value creation mechanisms. In the findings, six different capitals are identified from the participating stakeholders, and the value created, destroyed, and missed is discussed in the context of shared value principles. The findings show that capitals are used as inputs into the Hourglass Model and are consumed, created, and regenerated. There is also the realisation from the findings that different stakeholders required different and varying amounts of the six capitals identified. The interconnectedness of the capitals is shown in the study, and the findings show that the context of the environment within which a project operates contributes to the creation of shared value. As with the six capitals, the findings show that multiple stakeholders create shared value confirming stakeholder theory's guiding principles regarding stakeholder salience, which are relevant for creating shared value. Some stakeholders are identified as being more important to creating shared value in the project than others. Trade-offs are then required for value creation from a finite pool of capitals and stakeholders to consider the capitals and stakeholders' long and short-term impacts. Identifying stakeholders and the capitals allowed the researcher to consider the value created, destroyed and missed in the project. This assessment of shared value generated forms part of the findings on business models' outcomes for shared value, summarised for the project. Based on these areas where the outcomes are missing or destroying value, recommendations are made to address these opportunities, and an area of further research is identified. Drawing on these outcomes, developing clusters as per the value creation avenues of shared value would be the most appropriate avenue for this project. The study adds to the shared value body of knowledge by operationalising the Hourglass Model (Ludeke-Freund et al., 2016) and illustrating how the Model can be used to consider shared value creation. , Thesis (MBA) -- Faculty of Commerce, Rhodes Business School, 2021
- Full Text:
- Date Issued: 2021-04
Bioethical analysis of selected biomedical issues in South Africa and other countries
- Authors: Rusere, Jean
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/178530 , vital:42948
- Description: Access restricted until April 2023. , Thesis (MPharm) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Rusere, Jean
- Date: 2021-04
- Subjects: To be added
- Language: English
- Type: thesis , text , Masters , MPharm
- Identifier: http://hdl.handle.net/10962/178530 , vital:42948
- Description: Access restricted until April 2023. , Thesis (MPharm) -- Faculty of Pharmacy, Pharmacy, 2021
- Full Text:
- Date Issued: 2021-04
Photodynamic antimicrobial chemotherapy against Staphylococcus aureus and Escherichia coli sensitized using indium (III) cationic porphyrins linked to core-shell magnetic nanoparticles
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Makola, Lekgowa Collen
- Date: 2021-04
- Subjects: Photochemotherapy , Photosensitizing compounds , Staphylococcus aureus , Escherichia coli , Indium , Porphyrins , Magnetic nanoparticles , Quaternize
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177225 , vital:42801
- Description: Photodynamic antimicrobial chemotherapy (PACT) is a well-known antimicrobial therapy technique used against multi-drug resistant pathogens. In this study, the syntheses, characterization, photophysicochemical properties, and the applications of symmetrically and asymmetrically substituted cationic indium (III) porphyrins linked to silver/copper ferrite core-shell (Ag/CuFe2O4) magnetic nanoparticles (MNPs) as potential photosensitizers for PACT are reported. The synthesized complexes include axially modified porphyrins quaternized through an axial ligand. All the asymmetrically substituted porphyrins were linked to the NPs via an ester bond and the symmetrically substituted porphyrins were linked (peripherally and /or axially) via self-assembly (Ag-S and/or Ag-N). The impact of axial modification, peripheral substituents, conjugation to the NPs, the number of positive charges, and the chain length of the alkyl halides quaternizing agents on PACT efficacy and photophysicochemical properties of porphyrins were studied. High singlet oxygen quantum yields and antimicrobial log reductions were observed. Lipophilicity and hydrophilicity of the porphyrins were also studies, where the complexes quaternized with methyl iodide showed relatively high hydrophilicity character. Upon in vitro PACT studies, the quaternized complexes were observed to have 0% viable colony, signifying their effectiveness. Moreover, the highest log reductions of 9.27 were observed against S. aureus and 9.58 were observed against E. coli. The findings from this work delineate that singlet oxygen generation alone is not a distinct factor on the PACT efficacy of the porphyrin complexes, since some of the complexes have practically the same singlet oxygen quantum but different PACT activity. However, other contributing factors including water solubility play a significant role. , Thesis (MSc) -- Faculty of Science, Department of Chemistry, 2021
- Full Text:
- Date Issued: 2021-04
How selected Grade 7 participants develop conceptual understanding in solving algebraic problems as a result of participating in a screencast intervention
- Authors: Wienekus, George Renier
- Date: 2021-04
- Subjects: Algebra -- Study and teaching -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa , Problem solving in children , Algebra -- Ability testing , Algebra -- Computer-assisted instruction
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/176833 , vital:42763
- Description: This research project is an interventionist case study, oriented in the interpretive paradigm, which aims to investigate how selected Grade 7 participants develop conceptual understanding in solving algebraic problems as a result of participating in screencast interventions. The aim of my screencast intervention programme, which lies at the heart of this study, is to develop practices, inter alia, of how such devices and software may be “used to develop conceptual rather than procedural or decorative knowledge” (Larkin & Calder, 2015:1) in solving linear equations. The planned intervention was delivered in the form of a series of screencasts: these take the form of audio-video lessons with an emphasis on the visual impact, and were recorded using an application called Explain Everything. The screencast interventions were delivered via Google Classroom and included animations supported by such conceptual explanations of early algebra as are relevant to Grade 7 students, and in line with the South African Curriculum and Assessment Policy Statements - Department of Education, 2011. The fundamental components of an early algebraic equation that would be relevant to a Grade 7 student were considered and used to develop an analytic framework. This was based on a taxonomy designed according to four identified “clusters” in order to analyse the workings of the purposefully selected Grade 7 participants who were video recorded and questioned in a talk-aloud interview while they completed a post-intervention pencil-and-paper test. What emerges from this research project is that there is a significant need for specific and concentrated technology-based techniques, such as the interventions undertaken here, and that exploration and development in the field could benefit the delivery of a pedagogy for algebra. The pedagogical methods implemented and studied in the form of screencasts proved to be successful and were well received by the learners particularly in relation to the conceptualisation of “symbol sense” and transformation in early algebra. The structure and design of the screencast interventions were important in supporting the acquisition of these concepts and were demonstrated to be worthwhile tools for an epistemological application in a classroom or teaching context. , Thesis (MEd) -- Rhodes University, Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Wienekus, George Renier
- Date: 2021-04
- Subjects: Algebra -- Study and teaching -- South Africa , Mathematics -- Study and teaching (Elementary) -- South Africa , Problem solving in children , Algebra -- Ability testing , Algebra -- Computer-assisted instruction
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/176833 , vital:42763
- Description: This research project is an interventionist case study, oriented in the interpretive paradigm, which aims to investigate how selected Grade 7 participants develop conceptual understanding in solving algebraic problems as a result of participating in screencast interventions. The aim of my screencast intervention programme, which lies at the heart of this study, is to develop practices, inter alia, of how such devices and software may be “used to develop conceptual rather than procedural or decorative knowledge” (Larkin & Calder, 2015:1) in solving linear equations. The planned intervention was delivered in the form of a series of screencasts: these take the form of audio-video lessons with an emphasis on the visual impact, and were recorded using an application called Explain Everything. The screencast interventions were delivered via Google Classroom and included animations supported by such conceptual explanations of early algebra as are relevant to Grade 7 students, and in line with the South African Curriculum and Assessment Policy Statements - Department of Education, 2011. The fundamental components of an early algebraic equation that would be relevant to a Grade 7 student were considered and used to develop an analytic framework. This was based on a taxonomy designed according to four identified “clusters” in order to analyse the workings of the purposefully selected Grade 7 participants who were video recorded and questioned in a talk-aloud interview while they completed a post-intervention pencil-and-paper test. What emerges from this research project is that there is a significant need for specific and concentrated technology-based techniques, such as the interventions undertaken here, and that exploration and development in the field could benefit the delivery of a pedagogy for algebra. The pedagogical methods implemented and studied in the form of screencasts proved to be successful and were well received by the learners particularly in relation to the conceptualisation of “symbol sense” and transformation in early algebra. The structure and design of the screencast interventions were important in supporting the acquisition of these concepts and were demonstrated to be worthwhile tools for an epistemological application in a classroom or teaching context. , Thesis (MEd) -- Rhodes University, Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
Exploring the influences of an intersemiotic complementarity teaching approach on Grade 9 Namibian learners’ sense-making of chemical bonding
- Aikanga, Frans Paulus Shintaleleni
- Authors: Aikanga, Frans Paulus Shintaleleni
- Date: 2021-04
- Subjects: Physical sciences -- Study and teaching (Secondary) -- Namibia , Chemical bonds , Semiotics , Cognition in children , Communication in education , Language and education -- Namibia , Visual learning , Verbal learning
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/178281 , vital:42927
- Description: Anecdotal evidence from my 10 years’ experience teaching Grade 9 Physical Science in Namibian schools revealed learners’ difficulty with making sense of chemical bonding. The Junior Secondary examiners’ reports in recent consecutive years (2014, 2015, 2016 & 2017) also revealed this challenge among Grade 10 learners (Namibia. Ministry of Education, Arts and Culture [MoEAC], 2017). The language of learning and teaching (LoLT) for most school subjects (including Physical Science) in Namibia is English, which is taken as a second language by most learners (Kisting, 2011). The results of the English Language Proficiency test written by all principals and teachers in Namibia show that most are not proficient in this language (Kisting, 2011). This has raised concern as to how teaching of content subjects may be undertaken effectively with English as the LoLT. In Namibia, chemical bonding is part of the chemistry section of Physical Science, taught as a sub-topic under the Matter section, where the nature, characteristics, and behaviour of three states of matter are explained. The difficulty students have with chemical bonding is identified as being due to complex chemical concepts (Chittleborough & Mamiala, 2006), and the specialised language of the topic these concepts involve (Gilbert & Treagust, 2009). Additionally, this difficulty may be ascribed to lack of suitable pedagogic approaches, which is linked to science teachers not being fluent in the LoLT. Despite this link, Johnstone (1982) posits that addressing the challenge of teaching and learning chemical knowledge requires teachers’ understanding of three levels of representation: macroscopic, sub-microscopic, and symbolic. Addressing this challenge may be accomplished by using multimodality in teaching, which is achievable via intersemiosis of different semiotic modes, drawing from Systemic Functional Linguistics. This is due to non-linguistic modes also having the potential to make meaning as language does, and the fact that language alone cannot fully enable effective meaning-making in discourses that are inherently multimodal, such as science. Some studies have suggested that the intersemiosis of visual and verbal semiotic modes has the potential to enable more meaning-making of scientific discourse than either of these two alone. The study reported on in this thesis has built on such previous studies in order to explore the influences of a visual-verbal intersemiotic complementarity teaching approach on Grade 9 Namibian learners’ sense-making of chemical bonding. No studies from Namibia exploring these influences on Grade 9 learners could be found. This revealed the knowledge gap that this study aimed to contribute to filling. I accomplished this goal by embarking on a two-cycle action research study. The first cycle followed a traditional teaching approach and assessment, whereas the second cycle, the intervention, included a visual-verbal intersemiotic complementarity teaching approach and assessment. I achieved visual-verbal intersemiotic complementarity teaching and assessment by coordinating spoken and written language with visuals in the form of diagrams and physical models. The critical paradigm was adopted to explore the influences of this pedagogic approach, with the underlying aim of exploring the intervention approach for bringing about a change in learners’ sense-making of chemical bonding, compared to traditional approaches that do not consider intersemiosis. This study is informed by Vygotsky’s (1978) social constructivism to account for learning as a product of social construction, and Halliday’s (1978) Systemic Functional Linguistics to account for the role played by semiotic modes in making meanings. This study involved collecting qualitative data that were accessed via document analysis, structured lesson observation, the teacher’s and learners’ reflective journals, and the pre- and post-test. Collecting these data was facilitated by a critical friend. The results reveal a positive influence of the visual-verbal intersemiotic complementarity teaching approach on Grade 9 Namibian learners’ sense-making of chemical bonding. This influence was realised in the noticeable shift from the learners’ discourse (use of talk and visuals) being perceptual (which is less scientific) to being idea-based (which is more scientific). Learners were also found to be self-motivated and keen to learn complex chemical bonding concepts after the intervention – another sign of their making sense of the topic. The implications of this study include that visual-verbal intersemiotic complementarity should be considered a pedagogic approach to chemical bonding by curriculum developers and reviewers, teacher training institutions, and science textbook authors. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Aikanga, Frans Paulus Shintaleleni
- Date: 2021-04
- Subjects: Physical sciences -- Study and teaching (Secondary) -- Namibia , Chemical bonds , Semiotics , Cognition in children , Communication in education , Language and education -- Namibia , Visual learning , Verbal learning
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/178281 , vital:42927
- Description: Anecdotal evidence from my 10 years’ experience teaching Grade 9 Physical Science in Namibian schools revealed learners’ difficulty with making sense of chemical bonding. The Junior Secondary examiners’ reports in recent consecutive years (2014, 2015, 2016 & 2017) also revealed this challenge among Grade 10 learners (Namibia. Ministry of Education, Arts and Culture [MoEAC], 2017). The language of learning and teaching (LoLT) for most school subjects (including Physical Science) in Namibia is English, which is taken as a second language by most learners (Kisting, 2011). The results of the English Language Proficiency test written by all principals and teachers in Namibia show that most are not proficient in this language (Kisting, 2011). This has raised concern as to how teaching of content subjects may be undertaken effectively with English as the LoLT. In Namibia, chemical bonding is part of the chemistry section of Physical Science, taught as a sub-topic under the Matter section, where the nature, characteristics, and behaviour of three states of matter are explained. The difficulty students have with chemical bonding is identified as being due to complex chemical concepts (Chittleborough & Mamiala, 2006), and the specialised language of the topic these concepts involve (Gilbert & Treagust, 2009). Additionally, this difficulty may be ascribed to lack of suitable pedagogic approaches, which is linked to science teachers not being fluent in the LoLT. Despite this link, Johnstone (1982) posits that addressing the challenge of teaching and learning chemical knowledge requires teachers’ understanding of three levels of representation: macroscopic, sub-microscopic, and symbolic. Addressing this challenge may be accomplished by using multimodality in teaching, which is achievable via intersemiosis of different semiotic modes, drawing from Systemic Functional Linguistics. This is due to non-linguistic modes also having the potential to make meaning as language does, and the fact that language alone cannot fully enable effective meaning-making in discourses that are inherently multimodal, such as science. Some studies have suggested that the intersemiosis of visual and verbal semiotic modes has the potential to enable more meaning-making of scientific discourse than either of these two alone. The study reported on in this thesis has built on such previous studies in order to explore the influences of a visual-verbal intersemiotic complementarity teaching approach on Grade 9 Namibian learners’ sense-making of chemical bonding. No studies from Namibia exploring these influences on Grade 9 learners could be found. This revealed the knowledge gap that this study aimed to contribute to filling. I accomplished this goal by embarking on a two-cycle action research study. The first cycle followed a traditional teaching approach and assessment, whereas the second cycle, the intervention, included a visual-verbal intersemiotic complementarity teaching approach and assessment. I achieved visual-verbal intersemiotic complementarity teaching and assessment by coordinating spoken and written language with visuals in the form of diagrams and physical models. The critical paradigm was adopted to explore the influences of this pedagogic approach, with the underlying aim of exploring the intervention approach for bringing about a change in learners’ sense-making of chemical bonding, compared to traditional approaches that do not consider intersemiosis. This study is informed by Vygotsky’s (1978) social constructivism to account for learning as a product of social construction, and Halliday’s (1978) Systemic Functional Linguistics to account for the role played by semiotic modes in making meanings. This study involved collecting qualitative data that were accessed via document analysis, structured lesson observation, the teacher’s and learners’ reflective journals, and the pre- and post-test. Collecting these data was facilitated by a critical friend. The results reveal a positive influence of the visual-verbal intersemiotic complementarity teaching approach on Grade 9 Namibian learners’ sense-making of chemical bonding. This influence was realised in the noticeable shift from the learners’ discourse (use of talk and visuals) being perceptual (which is less scientific) to being idea-based (which is more scientific). Learners were also found to be self-motivated and keen to learn complex chemical bonding concepts after the intervention – another sign of their making sense of the topic. The implications of this study include that visual-verbal intersemiotic complementarity should be considered a pedagogic approach to chemical bonding by curriculum developers and reviewers, teacher training institutions, and science textbook authors. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
An analysis of the countervailing measures used to address the anti-competitive effects of Government subsidies in the African Continental Free Trade Area
- Authors: Matsimbi, Rhulani Shaun
- Date: 2021-04
- Subjects: Subsidies -- Law and legislation -- Africa , Agreement on Subsidies and Countervailing Measures (1994 April 15) , Trade regulation -- Africa , World Trade Organization , Antitrust law -- Africa , Restraint of trade -- Africa , African Continental Free Trade (AfCFTA) Agreement
- Language: English
- Type: thesis , text , Masters , LLM
- Identifier: http://hdl.handle.net/10962/178330 , vital:42930
- Description: Government subsidies are becoming more prevalent on the African continent. Subsidies allow the government to intervene in markets to incentivise more investment into nascent and struggling industries by improving the efficiency of firms in such industries. As such, subsidies form an essential part of some African countries’ industrialisation policies. However, the use of subsidies faces a challenge because of the prohibition contained in the World Trade Organisation’s (WTO) Agreement on Subsidies and Countervailing Measures (SCM Agreement). The SCM Agreement prohibits the granting of subsidies that are contingent on export performance or the use of domestic over imported content. While African countries have not faced challenges in the WTO for their use of these subsidies, this may change with the operation of the African Continental Free Trade (AfCFTA) Agreement. This is because the AfCFTA Agreement localises the WTO’s rules on subsidisation. This study critically examines the provisions in the AfCFTA Guidelines on the Implementation of Trade Remedies that regulate the use of export subsidies and subsidies contingent on the use of domestic content. It discusses how the absolute prohibition of these subsidies in the AfCFTA Agreement is not the most effective way to regulate their anti-competitive effects in the African continent. Specifically, this study discusses the role that competition policy might play in ensuring that export subsidies and local content subsidies are regulated in a manner that suits Africa’s context. Ultimately, this study concludes and recommends that the AfCFTA must develop unique rules to regulate subsidies in a way that caters to the needs of the continent. , Thesis (LLM) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Matsimbi, Rhulani Shaun
- Date: 2021-04
- Subjects: Subsidies -- Law and legislation -- Africa , Agreement on Subsidies and Countervailing Measures (1994 April 15) , Trade regulation -- Africa , World Trade Organization , Antitrust law -- Africa , Restraint of trade -- Africa , African Continental Free Trade (AfCFTA) Agreement
- Language: English
- Type: thesis , text , Masters , LLM
- Identifier: http://hdl.handle.net/10962/178330 , vital:42930
- Description: Government subsidies are becoming more prevalent on the African continent. Subsidies allow the government to intervene in markets to incentivise more investment into nascent and struggling industries by improving the efficiency of firms in such industries. As such, subsidies form an essential part of some African countries’ industrialisation policies. However, the use of subsidies faces a challenge because of the prohibition contained in the World Trade Organisation’s (WTO) Agreement on Subsidies and Countervailing Measures (SCM Agreement). The SCM Agreement prohibits the granting of subsidies that are contingent on export performance or the use of domestic over imported content. While African countries have not faced challenges in the WTO for their use of these subsidies, this may change with the operation of the African Continental Free Trade (AfCFTA) Agreement. This is because the AfCFTA Agreement localises the WTO’s rules on subsidisation. This study critically examines the provisions in the AfCFTA Guidelines on the Implementation of Trade Remedies that regulate the use of export subsidies and subsidies contingent on the use of domestic content. It discusses how the absolute prohibition of these subsidies in the AfCFTA Agreement is not the most effective way to regulate their anti-competitive effects in the African continent. Specifically, this study discusses the role that competition policy might play in ensuring that export subsidies and local content subsidies are regulated in a manner that suits Africa’s context. Ultimately, this study concludes and recommends that the AfCFTA must develop unique rules to regulate subsidies in a way that caters to the needs of the continent. , Thesis (LLM) -- Faculty of Law, Law, 2021
- Full Text:
- Date Issued: 2021-04
Exploring how Grade 9 Physical Science teachers mediate learning of the topic of chemical changes
- Likando, Orrice Munukayumbwa
- Authors: Likando, Orrice Munukayumbwa
- Date: 2021-04
- Subjects: Science -- Study and teaching (Secondary) -- Namibia , Chemistry -- Study and teaching (Secondary) -- Namibia , Culturally relevant pedagogy , Pedagogical content knowledge , Prior learning -- Namibia
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177918 , vital:42890
- Description: The examiners’ reports for 2013-2018 indicated that learners consistently perform poorly in questions based on chemical changes. My assumption is that the reason why learners are challenged with understanding the topic of chemical changes could be due to the way this topic is taught. It is against this background that this study explored how grade 9 Physical Science teachers mediated learning of the topic of chemical changes. The study is underpinned by an interpretive paradigm. Within the interpretive paradigm, a qualitative case study research design was employed. It was conducted at two different schools in the Otjozondjupa region with two Physical Science teachers. Data were collected using semi-structured interviews, lesson observations, stimulated recall interviews, and teachers’ reflections. The study is informed by Vygotsky’s socio-cultural theory together with Shulman’s pedagogical content knowledge as the theoretical frameworks. A thematic approach to data analysis was adopted. That is, qualitative data were analysed inductively to come up with sub-themes to form themes. Moreover, validation and trustworthiness were completed through data triangulation, member checking, and watching videotaped lessons with the participants. The findings of this study revealed that the topic of chemical changes has many examples which can be used during mediation. Teachers seemed to be aware of integrating learners’ experiences into their lessons. Furthermore, they were aware that they should improvise resources during mediation of learning. In contrast, during lesson observations, the findings revealed an imbalance between this awareness and the actual knowledge of using easily accessible materials, and the elicitation and integration of prior knowledge throughout the science lessons. Moreover, hands-on practical activities were lacking in the mediation process and instead, traditional methods of teaching tended to dominate. Nonetheless, teachers’ reflections influenced them to analyse and strengthen their lessons. Thus, the study recommends that there is a need for teachers to have mentorships and platforms which can expose them to the knowledge of different types of easily accessible materials. This might strengthen their PCK. Teachers are also encouraged to do some reflections after very lesson as these have a potential to influence their pedagogical practices. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Likando, Orrice Munukayumbwa
- Date: 2021-04
- Subjects: Science -- Study and teaching (Secondary) -- Namibia , Chemistry -- Study and teaching (Secondary) -- Namibia , Culturally relevant pedagogy , Pedagogical content knowledge , Prior learning -- Namibia
- Language: English
- Type: thesis , text , Masters , MEd
- Identifier: http://hdl.handle.net/10962/177918 , vital:42890
- Description: The examiners’ reports for 2013-2018 indicated that learners consistently perform poorly in questions based on chemical changes. My assumption is that the reason why learners are challenged with understanding the topic of chemical changes could be due to the way this topic is taught. It is against this background that this study explored how grade 9 Physical Science teachers mediated learning of the topic of chemical changes. The study is underpinned by an interpretive paradigm. Within the interpretive paradigm, a qualitative case study research design was employed. It was conducted at two different schools in the Otjozondjupa region with two Physical Science teachers. Data were collected using semi-structured interviews, lesson observations, stimulated recall interviews, and teachers’ reflections. The study is informed by Vygotsky’s socio-cultural theory together with Shulman’s pedagogical content knowledge as the theoretical frameworks. A thematic approach to data analysis was adopted. That is, qualitative data were analysed inductively to come up with sub-themes to form themes. Moreover, validation and trustworthiness were completed through data triangulation, member checking, and watching videotaped lessons with the participants. The findings of this study revealed that the topic of chemical changes has many examples which can be used during mediation. Teachers seemed to be aware of integrating learners’ experiences into their lessons. Furthermore, they were aware that they should improvise resources during mediation of learning. In contrast, during lesson observations, the findings revealed an imbalance between this awareness and the actual knowledge of using easily accessible materials, and the elicitation and integration of prior knowledge throughout the science lessons. Moreover, hands-on practical activities were lacking in the mediation process and instead, traditional methods of teaching tended to dominate. Nonetheless, teachers’ reflections influenced them to analyse and strengthen their lessons. Thus, the study recommends that there is a need for teachers to have mentorships and platforms which can expose them to the knowledge of different types of easily accessible materials. This might strengthen their PCK. Teachers are also encouraged to do some reflections after very lesson as these have a potential to influence their pedagogical practices. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-04
The development, manufacture and characterisation of tenofovir encapsulated liposomes
- Authors: Mungoshi, Fadzai Naomi
- Date: 2020-04
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc (Pharmacy)
- Identifier: http://hdl.handle.net/10962/164524 , vital:41126
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020-04
- Authors: Mungoshi, Fadzai Naomi
- Date: 2020-04
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc (Pharmacy)
- Identifier: http://hdl.handle.net/10962/164524 , vital:41126
- Description: Thesis (MSc)--Rhodes University, Faculty of Pharmacy, Pharmaceutics, 2020
- Full Text:
- Date Issued: 2020-04
Development of a low-cost bioprinting system for engineering of Human Tumour Models
- Authors: Fanucci, Sidne
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163295 , vital:41026
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Fanucci, Sidne
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163295 , vital:41026
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Biotechnology Innovation Centre, 2020.
- Full Text:
- Date Issued: 2020
Physical activity, physical fitness, sedentary behaviour and screen time profiles of primary school children in a school within the Makana Municipality, Eastern Cape, South Africa
- Authors: Kade, Andréa Gaby
- Date: 2021-04
- Subjects: Sedentary behavior in children -- South Africa -- Makana Municipality , Physical fitness for children -- South Africa -- Makana Municipality , Exercise -- Physiological aspects , Exercise -- Health aspects , Diabetes -- Risk factors , Heart -- Diseases -- Risk factors
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177282 , vital:42806
- Description: There is a lack of data on the physical activity, physical fitness and sedentary behaviour of children in South Africa. Furthermore chronic diseases such as type II diabetes and coronary heart disease have been linked to childhood inactivity, and improving cardiorespiratory fitness and increasing levels of physical activity has been shown to be beneficial in reducing the risk of such diseases. In South Africa more broadly there is a lack of information on levels of physical activity and sedentary behaviour as well as physical fitness measures particularly in children. Objective: The purpose of this study was to enhance the existing body of knowledge on this, by measuring the prevalence of physical inactivity, sedentary behaviour and screen time of primary school children in a private school from the Makana Municipal region in the Eastern Cape Province of South Africa, where the evidence is most sparse. A secondary aim was to assess levels of physical fitness in this cohort, as well as to compare across grades and sexes. Method: After ethical approval was granted, stature and body mass measurements were taken and body mass index was computed for primary school children (Grade one to seven) from a private school in the Makana Municipality. Sitting stature was measured in order to determine each child’s peak height velocity and maturity offset. Five different physical fitness tests were conducted on the children and blood pressure and heart rate values were measured at rest. Physical activity and screen time questionnaires were completed by the children’s parents for a seven day period. Results: Females were found to mature faster than males. In addition females were more physically active (Females= 916 min/week; Males= 669 min/week) while also accumulating more sedentary time (Females= 1241 min/week; Males= 970 min/week) as compared to males, although no significant differences were found between males and females for these variables. The sample participated in more than 60 minutes of moderate-to-vigorous physical activity and less than two hours of screen time daily, which is in accordance with guidelines. No differences were found between grades and sexes for accumulated screen time. Strength increased significantly with grade and age, and there were also statistical differences between the sexes for all three strength measures with males being stronger than females. Females were more flexible than males and no statistical differences were found between sexes for the shuttle run test. Blood pressure correlated positively with mass, as did all the strength measures as well as maturity offset. No correlations were found between screen time and all other variables. A negative relationship was recorded between screen time and physical activity, although not significant. For females a strong positive correlation was found between sedentary behaviour and physical activity. Conclusion: The study was successful in adding to the body of knowledge regarding the prevalence of physical inactivity, sedentary behaviour and screen time within school children from the Makana Municipality in the Eastern Cape Province of South Africa. The sample was considered physically active as they accumulated on average more than 60 minutes of moderate-to-vigorous physical activity daily (Males= 96 min/day; Females 130 min/day), which is in accordance with guidelines recommended by the World Health Organization (World Health Organization, 2018). The sample accumulated more sedentary behaviour than physical activity, although not significant. Screen time was below regulations of two hours daily, indicating this population participated in more non screen related sedentary behaviour. More research is needed into the risks presented with different forms of sedentary behaviour. Physical fitness increased with increasing grade and age and males were considerably more fit. The current study did not present any concern with regards to the effects of increased physical activity and fitness levels within school aged children. More research into the current levels of physical activity, physical fitness and sedentary behaviour of school aged children in South Africa in general, and in the Eastern Cape Province, is needed. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Kade, Andréa Gaby
- Date: 2021-04
- Subjects: Sedentary behavior in children -- South Africa -- Makana Municipality , Physical fitness for children -- South Africa -- Makana Municipality , Exercise -- Physiological aspects , Exercise -- Health aspects , Diabetes -- Risk factors , Heart -- Diseases -- Risk factors
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177282 , vital:42806
- Description: There is a lack of data on the physical activity, physical fitness and sedentary behaviour of children in South Africa. Furthermore chronic diseases such as type II diabetes and coronary heart disease have been linked to childhood inactivity, and improving cardiorespiratory fitness and increasing levels of physical activity has been shown to be beneficial in reducing the risk of such diseases. In South Africa more broadly there is a lack of information on levels of physical activity and sedentary behaviour as well as physical fitness measures particularly in children. Objective: The purpose of this study was to enhance the existing body of knowledge on this, by measuring the prevalence of physical inactivity, sedentary behaviour and screen time of primary school children in a private school from the Makana Municipal region in the Eastern Cape Province of South Africa, where the evidence is most sparse. A secondary aim was to assess levels of physical fitness in this cohort, as well as to compare across grades and sexes. Method: After ethical approval was granted, stature and body mass measurements were taken and body mass index was computed for primary school children (Grade one to seven) from a private school in the Makana Municipality. Sitting stature was measured in order to determine each child’s peak height velocity and maturity offset. Five different physical fitness tests were conducted on the children and blood pressure and heart rate values were measured at rest. Physical activity and screen time questionnaires were completed by the children’s parents for a seven day period. Results: Females were found to mature faster than males. In addition females were more physically active (Females= 916 min/week; Males= 669 min/week) while also accumulating more sedentary time (Females= 1241 min/week; Males= 970 min/week) as compared to males, although no significant differences were found between males and females for these variables. The sample participated in more than 60 minutes of moderate-to-vigorous physical activity and less than two hours of screen time daily, which is in accordance with guidelines. No differences were found between grades and sexes for accumulated screen time. Strength increased significantly with grade and age, and there were also statistical differences between the sexes for all three strength measures with males being stronger than females. Females were more flexible than males and no statistical differences were found between sexes for the shuttle run test. Blood pressure correlated positively with mass, as did all the strength measures as well as maturity offset. No correlations were found between screen time and all other variables. A negative relationship was recorded between screen time and physical activity, although not significant. For females a strong positive correlation was found between sedentary behaviour and physical activity. Conclusion: The study was successful in adding to the body of knowledge regarding the prevalence of physical inactivity, sedentary behaviour and screen time within school children from the Makana Municipality in the Eastern Cape Province of South Africa. The sample was considered physically active as they accumulated on average more than 60 minutes of moderate-to-vigorous physical activity daily (Males= 96 min/day; Females 130 min/day), which is in accordance with guidelines recommended by the World Health Organization (World Health Organization, 2018). The sample accumulated more sedentary behaviour than physical activity, although not significant. Screen time was below regulations of two hours daily, indicating this population participated in more non screen related sedentary behaviour. More research is needed into the risks presented with different forms of sedentary behaviour. Physical fitness increased with increasing grade and age and males were considerably more fit. The current study did not present any concern with regards to the effects of increased physical activity and fitness levels within school aged children. More research into the current levels of physical activity, physical fitness and sedentary behaviour of school aged children in South Africa in general, and in the Eastern Cape Province, is needed. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-04
Inhibitor search and variant analysis of Acetylcholinesterase
- Authors: Ras, Harnaud
- Date: 2021-04
- Subjects: Acetylcholinesterase , Alzheimer's disease , Acetylcholinesterase -- Inhibitors , Alzheimer's disease -- Chemotherapy , Cerebrovascular disease -- Treatment , Molecular mechanics Poisson–Boltzmann surface area (MM-PBSA)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178191 , vital:42919
- Description: Acetylcholinesterase (AChE) inhibition is used to treat Alzheimer's disease by increasing the availability of acetylcholine to carry nerve signals in the brain. The response to this treatment varies widely, which may be due to altered affnity to the current drugs caused by genetic variation. Various negative side-effects limit their use. As this is one of the only available therapeutic drug targets to treat Alzheimer's disease, decreasing the negative effects is of great importance. AChE is involved in biological processes that occur after acute ischemic stroke. Stroke is the third leading cause of death worldwide, and 87% of all stroke cases belong to ischemic stroke. AchEI (cholinesterase inhibitors) have been suggested to have properties that lower the risk of stroke. AChE is one of 15 verified drug targets under study for treatment of stroke. In addition to Alzheimer's disease and stroke, Lewy body disease (LBD) may be treated using cholinesterase inhibitors. The goals of this study are to find inhibitors that can potentially be used to treat Alzheimer's disease and/or stroke and to investigate variants which may affect protein dynamics and function. Two variants were analyzed, P247L and T229S. Molecular simulation of the P247L variant resulted in a disruption in protein dynamics in comparison to the wildtype. A total of 5728 molecules were screened and 10 nanosecond simulations were used to narrow down the set of compounds. The four best performing molecules were simulated for 10 nanoseconds. MM-PBSA was performed to identify molecules with high binding free energies. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Ras, Harnaud
- Date: 2021-04
- Subjects: Acetylcholinesterase , Alzheimer's disease , Acetylcholinesterase -- Inhibitors , Alzheimer's disease -- Chemotherapy , Cerebrovascular disease -- Treatment , Molecular mechanics Poisson–Boltzmann surface area (MM-PBSA)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/178191 , vital:42919
- Description: Acetylcholinesterase (AChE) inhibition is used to treat Alzheimer's disease by increasing the availability of acetylcholine to carry nerve signals in the brain. The response to this treatment varies widely, which may be due to altered affnity to the current drugs caused by genetic variation. Various negative side-effects limit their use. As this is one of the only available therapeutic drug targets to treat Alzheimer's disease, decreasing the negative effects is of great importance. AChE is involved in biological processes that occur after acute ischemic stroke. Stroke is the third leading cause of death worldwide, and 87% of all stroke cases belong to ischemic stroke. AchEI (cholinesterase inhibitors) have been suggested to have properties that lower the risk of stroke. AChE is one of 15 verified drug targets under study for treatment of stroke. In addition to Alzheimer's disease and stroke, Lewy body disease (LBD) may be treated using cholinesterase inhibitors. The goals of this study are to find inhibitors that can potentially be used to treat Alzheimer's disease and/or stroke and to investigate variants which may affect protein dynamics and function. Two variants were analyzed, P247L and T229S. Molecular simulation of the P247L variant resulted in a disruption in protein dynamics in comparison to the wildtype. A total of 5728 molecules were screened and 10 nanosecond simulations were used to narrow down the set of compounds. The four best performing molecules were simulated for 10 nanoseconds. MM-PBSA was performed to identify molecules with high binding free energies. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
- Full Text:
- Date Issued: 2021-04
An investigation into the application of Distributed Endpoint Processing to 3D Immersive Audio Rendering
- Authors: Devonport, Robin Sean
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163258 , vital:41022
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Computer Science, 2020.
- Full Text:
- Date Issued: 2020
- Authors: Devonport, Robin Sean
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/163258 , vital:41022
- Description: Thesis (MSc)--Rhodes University, Faculty of Science, Computer Science, 2020.
- Full Text:
- Date Issued: 2020
Biology, ecology and management of the Keurboom moth, Leto venus Cramer and the leafhopper Molopopterus sp. Jacobi in cultivated Honeybush (Cyclopia spp.)
- Authors: Mushore, Tapiwa Gift
- Date: 2021-04
- Subjects: Legumes , Legumes -- Diseases and pests , Hepialidae , Leafhoppers , Pests -- Biological control , Entomopathogenic fungi , Leafhoppers -- Biological control , Hepialidae -- Biological control , Keurboom moth (Leto venus Cramer) , Molopopterus sp. Jacobi , Honeybush (Cyclopia spp.)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177125 , vital:42792
- Description: Honeybush, Cyclopia spp. Vent (Fabaceae), farmers have raised pest concerns following commercial cultivation. The Keurboom moth Leto venus Cramer (Lepidoptera: Hepialidae) and the leafhopper Molopopterus sp. Jacobi (Hemiptera: Cicadellidae), are two of the major pests identified in cultivated Honeybush. Laboratory and field studies were conducted to gain an understanding of the biology of these two pests to inform future pest management solutions. Additionally, entomopathogenic fungi were isolated from Honeybush farms and screened for virulence against Molopopterus sp. as a possible management strategy. This study showed that the L. venus infestation on Honeybush was a product of four fixed effects; stem diameter, species of Cyclopia, Farm location and age of the plants. Cyclopia subternata, had the highest likelihood of infestation. Increase in age of the plants resulted in an increase in the stem diameter and therefore a higher probability of infestation. Stem diameter was also shown to be a significant predictor of infestation likelihood. Infestation severity, determined by the number of larvae per plant, was shown to be influenced by three fixed effects; stem diameter, plant species and Farm location. The results also showed that L. venus prefers to initiate penetration at, or just aboveground level. Laboratory studies showed that the leafhopper Molopopterus sp. undergoes five nymphal instars with an average egg incubation time of 20 days, development time from 1st instar to adult of 26 days and average generation time of 47 days. Laboratory experiments revealed variations in host preference by the leafhopper over a period of 15 days. Cyclopia longifolia was identified to be the most preferred species for feeding compared to the two other commonly cultivated species, C. subternata and C. maculata. The results were consistent with those obtained from the field survey which showed that leafhopper density was influenced by four fixed effects; plant species, age of the plant, Farm location and harvesting practices. There were significant differences in leafhopper density in different species with C. longifolia having the highest number of leafhoppers per plant. There were differences in leafhopper density in different farms as 57% of the sampled farms had leafhopper infestations, of these farms, Lodestone and Kurland had the highest leafhopper densities. Harvested plants were shown to have significantly higher leafhopper density than non-harvested plants. Age was also shown to influence leafhopper density, which reduced with an increase in the age of the plants. A total of 20 fungal isolates were recovered from 98 soil samples of which 70% were from Honeybush fields and 30% were from surrounding refugia. Fusarium oxysporum isolates comprised 20% of the recovered isolates, with Metarhizium anisopliae isolates making up the remainder. Laboratory bioassays against adults and nymphs of the leafhopper, Molopopterus sp., showed that F. oxysporum isolates induced 10 – 45% mortality and M. anisopliae isolates induce 30 – 80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both Molopopterus sp. nymphs and adults. The results of this study showed pest preference towards different Cyclopia species. As such, they should be managed differently. Furthermore, L. venus was observed to occur in low densities, hence, it cannot be considered a major pest. However, Molopopterus sp. recorded high population densities making it a major pest in Honeybush production. Positive results indicated that some of the isolated fungal isolates have potential for control, an avenue worth investigating further. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Mushore, Tapiwa Gift
- Date: 2021-04
- Subjects: Legumes , Legumes -- Diseases and pests , Hepialidae , Leafhoppers , Pests -- Biological control , Entomopathogenic fungi , Leafhoppers -- Biological control , Hepialidae -- Biological control , Keurboom moth (Leto venus Cramer) , Molopopterus sp. Jacobi , Honeybush (Cyclopia spp.)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/177125 , vital:42792
- Description: Honeybush, Cyclopia spp. Vent (Fabaceae), farmers have raised pest concerns following commercial cultivation. The Keurboom moth Leto venus Cramer (Lepidoptera: Hepialidae) and the leafhopper Molopopterus sp. Jacobi (Hemiptera: Cicadellidae), are two of the major pests identified in cultivated Honeybush. Laboratory and field studies were conducted to gain an understanding of the biology of these two pests to inform future pest management solutions. Additionally, entomopathogenic fungi were isolated from Honeybush farms and screened for virulence against Molopopterus sp. as a possible management strategy. This study showed that the L. venus infestation on Honeybush was a product of four fixed effects; stem diameter, species of Cyclopia, Farm location and age of the plants. Cyclopia subternata, had the highest likelihood of infestation. Increase in age of the plants resulted in an increase in the stem diameter and therefore a higher probability of infestation. Stem diameter was also shown to be a significant predictor of infestation likelihood. Infestation severity, determined by the number of larvae per plant, was shown to be influenced by three fixed effects; stem diameter, plant species and Farm location. The results also showed that L. venus prefers to initiate penetration at, or just aboveground level. Laboratory studies showed that the leafhopper Molopopterus sp. undergoes five nymphal instars with an average egg incubation time of 20 days, development time from 1st instar to adult of 26 days and average generation time of 47 days. Laboratory experiments revealed variations in host preference by the leafhopper over a period of 15 days. Cyclopia longifolia was identified to be the most preferred species for feeding compared to the two other commonly cultivated species, C. subternata and C. maculata. The results were consistent with those obtained from the field survey which showed that leafhopper density was influenced by four fixed effects; plant species, age of the plant, Farm location and harvesting practices. There were significant differences in leafhopper density in different species with C. longifolia having the highest number of leafhoppers per plant. There were differences in leafhopper density in different farms as 57% of the sampled farms had leafhopper infestations, of these farms, Lodestone and Kurland had the highest leafhopper densities. Harvested plants were shown to have significantly higher leafhopper density than non-harvested plants. Age was also shown to influence leafhopper density, which reduced with an increase in the age of the plants. A total of 20 fungal isolates were recovered from 98 soil samples of which 70% were from Honeybush fields and 30% were from surrounding refugia. Fusarium oxysporum isolates comprised 20% of the recovered isolates, with Metarhizium anisopliae isolates making up the remainder. Laboratory bioassays against adults and nymphs of the leafhopper, Molopopterus sp., showed that F. oxysporum isolates induced 10 – 45% mortality and M. anisopliae isolates induce 30 – 80% mortality. Metarhizium anisopliae isolates J S1, KF S3, KF S11, KF S13, LS1 and LS2 were the most virulent and induced over 60% mortality in both Molopopterus sp. nymphs and adults. The results of this study showed pest preference towards different Cyclopia species. As such, they should be managed differently. Furthermore, L. venus was observed to occur in low densities, hence, it cannot be considered a major pest. However, Molopopterus sp. recorded high population densities making it a major pest in Honeybush production. Positive results indicated that some of the isolated fungal isolates have potential for control, an avenue worth investigating further. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
Baculovirus synergism for improved management of false codling moth Thaumatotibia leucotreta Meyr. (Lepidoptera: Tortricidae)
- Authors: Taylor, David Graham
- Date: 2021-04
- Subjects: Baculoviruses , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Codling moth , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176942 , vital:42774
- Description: Baculoviruses are an environmentally friendly and effective agent for managing lepidopteran pests. This includes the management of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a serious pest of citrus in Southern Africa and a major threat to the South African citrus export industry. For more than 15 years, CrleGV-SA- based biopesticides have been used as part of an integrated pest management strategy for the control of T. leucotreta in citrus orchards in South Africa, under the names Cryptogran™ and Cryptex®. While these biopesticides have been effective during this period, there are some areas in which baculovirus use could potentially be improved. Baculoviruses are notoriously slow to kill in comparison to chemical-based pesticides, and lately, pest resistance to baculoviruses has become a major concern with the development of resistance by Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) to its granulovirus occurring in the field in Europe. The consistent use of CrleGV-SA for more than 15 years in the field has raised concern that T. leucotreta could develop resistance to this virus, and has made it necessary to alter baculovirus-based management strategies to prevent this from occurring. A second baculovirus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), has recently been isolated and was shown to be effective against T. leucotreta. However, the interactions between CrleGV-SA and CrpeNPV are not yet understood and so it is important to test these interactions before both viruses are applied on the same orchards. Not only is it important to know whether these viruses could negatively impact each other, but it is also important to test whether they could interact synergistically. A synergistic interaction could not only provide a potential tool for the management of resistance, but it could also be exploited to improve baculovirus-based management of T. leucotreta. In this study, a stock of CrleGV-SA was purified by glycerol gradient centrifugation from T. leucotreta cadavers, while a stock of CrpeNPV purified from Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) cadavers was provided by River Bioscience (Pty) Ltd. These stocks were screened for purity by a multiplex polymerase chain reaction (mPCR) protocol designed to detect CrleGV-SA and CrpeNPV. The occlusion body (OB) density was then calculated using darkfield microscopy and a counting chamber. Both stocks were shown to be pure within the limits of the mPCR protocol, and the CrleGV-SA and CrpeNPV stocks were calculated to contain 3.08 × 1011 OBs/mL and 1.92 × 1011 OBs/mL respectively The first aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the dose mortality, in terms of lethal concentration. This was calculated using 7-day surface-dose biological assays for each virus and a 1:1 mixture of OBs of the two against T. leucotreta neonates. The lethal concentrations of each treatment required to kill 50 % of larvae (LC50) and 90 % of larvae (LC90) for each treatment were then calculated and compared using a probit regression. The mixed infection performed significantly better than either virus by itself, while each virus by itself did not differ significantly from the other. The LC50 for CrleGV-SA, CrpeNPV and the mixed infection were 1.53 × 104 OBs/mL, 1.15 × 104 OBs/mL and 4.38 × 103 OBs/mL respectively. The LC90 of CrleGV-SA, CrpeNPV and the mixed infection were calculated to be 4.10 × 105 OBs/mL, 1.05 × 105 OBs/mL, and 4.09 × 104 OBs/mL respectively. The second aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the speed of kill. A time-response biological assay protocol was created that allowed for effective observation of the larvae. This was then used to generate time-mortality data that were analysed by a logit regression function to calculate and compare the treatments at the time of 50 % larval mortality (LT50) and the time of 90 % mortality (LT90). Each virus by itself did not differ significantly from the other, while the mixed infection took significantly longer to kill 50 % and 90 % of the larvae, suggesting that there is competition for resources between viruses during the secondary, systemic phase of infection. The LT50 for CrleGV-SA, CrpeNPV and the mixed infection were 117.5 hours, 113.5 hours and 139.0 hours respectively. The LT90 for CrleGV-SA, CrpeNPV and the mixed infection were 153.2 hours, 159.3, and 193.4 hours respectively. Finally, the composition of OBs recovered from the cadavers produced by the time-response biological assays were investigated by mPCR. A method for extracting gDNA from OBs in neonate-sized T. leucotreta larvae is described. The presence of CrpeNPV along with CrleGV-SA was noted in 4 out of 9 larvae inoculated with only CrleGV-SA. The presence of CrleGV-SA as well as CrpeNPV was noted in all but one larva inoculated with only CrpeNPV, and both CrleGV-SA and CrpeNPV were noted in all but one larva inoculated with a 1:1 mixture of the two, with one larva only being positive for CrleGV-SA. This suggests either stock contamination or the presence of covert infections of CrleGV-SA and CrpeNPV in the T. leucotreta population used in this study. This is the second study to report an improved lethal concentration of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates, and the first study to report the slower speed of kill of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates. While the improved lethal concentration of the mixed infection is a promising step in the future improvement of baculovirus-based biopesticides, it is at the cost of a slower speed of kill. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04
- Authors: Taylor, David Graham
- Date: 2021-04
- Subjects: Baculoviruses , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Codling moth , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
- Language: English
- Type: thesis , text , Masters , MSc
- Identifier: http://hdl.handle.net/10962/176942 , vital:42774
- Description: Baculoviruses are an environmentally friendly and effective agent for managing lepidopteran pests. This includes the management of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a serious pest of citrus in Southern Africa and a major threat to the South African citrus export industry. For more than 15 years, CrleGV-SA- based biopesticides have been used as part of an integrated pest management strategy for the control of T. leucotreta in citrus orchards in South Africa, under the names Cryptogran™ and Cryptex®. While these biopesticides have been effective during this period, there are some areas in which baculovirus use could potentially be improved. Baculoviruses are notoriously slow to kill in comparison to chemical-based pesticides, and lately, pest resistance to baculoviruses has become a major concern with the development of resistance by Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) to its granulovirus occurring in the field in Europe. The consistent use of CrleGV-SA for more than 15 years in the field has raised concern that T. leucotreta could develop resistance to this virus, and has made it necessary to alter baculovirus-based management strategies to prevent this from occurring. A second baculovirus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), has recently been isolated and was shown to be effective against T. leucotreta. However, the interactions between CrleGV-SA and CrpeNPV are not yet understood and so it is important to test these interactions before both viruses are applied on the same orchards. Not only is it important to know whether these viruses could negatively impact each other, but it is also important to test whether they could interact synergistically. A synergistic interaction could not only provide a potential tool for the management of resistance, but it could also be exploited to improve baculovirus-based management of T. leucotreta. In this study, a stock of CrleGV-SA was purified by glycerol gradient centrifugation from T. leucotreta cadavers, while a stock of CrpeNPV purified from Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) cadavers was provided by River Bioscience (Pty) Ltd. These stocks were screened for purity by a multiplex polymerase chain reaction (mPCR) protocol designed to detect CrleGV-SA and CrpeNPV. The occlusion body (OB) density was then calculated using darkfield microscopy and a counting chamber. Both stocks were shown to be pure within the limits of the mPCR protocol, and the CrleGV-SA and CrpeNPV stocks were calculated to contain 3.08 × 1011 OBs/mL and 1.92 × 1011 OBs/mL respectively The first aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the dose mortality, in terms of lethal concentration. This was calculated using 7-day surface-dose biological assays for each virus and a 1:1 mixture of OBs of the two against T. leucotreta neonates. The lethal concentrations of each treatment required to kill 50 % of larvae (LC50) and 90 % of larvae (LC90) for each treatment were then calculated and compared using a probit regression. The mixed infection performed significantly better than either virus by itself, while each virus by itself did not differ significantly from the other. The LC50 for CrleGV-SA, CrpeNPV and the mixed infection were 1.53 × 104 OBs/mL, 1.15 × 104 OBs/mL and 4.38 × 103 OBs/mL respectively. The LC90 of CrleGV-SA, CrpeNPV and the mixed infection were calculated to be 4.10 × 105 OBs/mL, 1.05 × 105 OBs/mL, and 4.09 × 104 OBs/mL respectively. The second aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the speed of kill. A time-response biological assay protocol was created that allowed for effective observation of the larvae. This was then used to generate time-mortality data that were analysed by a logit regression function to calculate and compare the treatments at the time of 50 % larval mortality (LT50) and the time of 90 % mortality (LT90). Each virus by itself did not differ significantly from the other, while the mixed infection took significantly longer to kill 50 % and 90 % of the larvae, suggesting that there is competition for resources between viruses during the secondary, systemic phase of infection. The LT50 for CrleGV-SA, CrpeNPV and the mixed infection were 117.5 hours, 113.5 hours and 139.0 hours respectively. The LT90 for CrleGV-SA, CrpeNPV and the mixed infection were 153.2 hours, 159.3, and 193.4 hours respectively. Finally, the composition of OBs recovered from the cadavers produced by the time-response biological assays were investigated by mPCR. A method for extracting gDNA from OBs in neonate-sized T. leucotreta larvae is described. The presence of CrpeNPV along with CrleGV-SA was noted in 4 out of 9 larvae inoculated with only CrleGV-SA. The presence of CrleGV-SA as well as CrpeNPV was noted in all but one larva inoculated with only CrpeNPV, and both CrleGV-SA and CrpeNPV were noted in all but one larva inoculated with a 1:1 mixture of the two, with one larva only being positive for CrleGV-SA. This suggests either stock contamination or the presence of covert infections of CrleGV-SA and CrpeNPV in the T. leucotreta population used in this study. This is the second study to report an improved lethal concentration of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates, and the first study to report the slower speed of kill of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates. While the improved lethal concentration of the mixed infection is a promising step in the future improvement of baculovirus-based biopesticides, it is at the cost of a slower speed of kill. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-04