An architecture for feedback-driven learning analytics
- Authors: Winfield, Philip John
- Date: 2023-12
- Subjects: Educational statistics -- Data processing , Education -- Research -- Statistical methods , Teacher-student relationships
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62744 , vital:72935
- Description: Feedback from students provides an opportunity to gain insights into students’ learning behaviour and participation in higher education learning and teaching. Academic staff are expected to constantly review and improve the learning and teaching environment where feedback contributes vital information toward pedagogical decision-making. Reviewing student feedback is essential but time-consuming, making it crucial to explore more effective and efficient ways to analyse and present feedback that encourages intervention and support. The general design science research evaluation pattern guided the construction and evaluation of a Feedback-Driven Architecture (FDA) for Learning Analytics (LA) to address this problem. An FDA implementation using a suitable case demonstrated each component validating the feasibility and effectiveness of the proposed design. The components identified for inclusion in the FDA were integrated within layers of a three-tiered architecture pattern. The data layer incorporates the collection, preparation and storage of learning management system data which includes free-form narrative student feedback. The application layer contains logic to support the analysis of free-form narrative student feedback and extraction of learning analytics. Arrangement and visualisation of information in the presentation layer aim to promote appropriate intervention and support. Evaluation using a case study showed that the FDA provided necessary guidelines for developing an implementation that produced feedbackdriven learning analytics. Data preparation transformed unstructured data into a suitable representation for effective analysis. Cohorts within narrative feedback responses were identified using the k-means clustering algorithm and latent Dirichlet allocation. Logistic regression and support vector machines were applied as predictive models and trained using extracted quantitative markers to predict academic success. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Winfield, Philip John
- Date: 2023-12
- Subjects: Educational statistics -- Data processing , Education -- Research -- Statistical methods , Teacher-student relationships
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62744 , vital:72935
- Description: Feedback from students provides an opportunity to gain insights into students’ learning behaviour and participation in higher education learning and teaching. Academic staff are expected to constantly review and improve the learning and teaching environment where feedback contributes vital information toward pedagogical decision-making. Reviewing student feedback is essential but time-consuming, making it crucial to explore more effective and efficient ways to analyse and present feedback that encourages intervention and support. The general design science research evaluation pattern guided the construction and evaluation of a Feedback-Driven Architecture (FDA) for Learning Analytics (LA) to address this problem. An FDA implementation using a suitable case demonstrated each component validating the feasibility and effectiveness of the proposed design. The components identified for inclusion in the FDA were integrated within layers of a three-tiered architecture pattern. The data layer incorporates the collection, preparation and storage of learning management system data which includes free-form narrative student feedback. The application layer contains logic to support the analysis of free-form narrative student feedback and extraction of learning analytics. Arrangement and visualisation of information in the presentation layer aim to promote appropriate intervention and support. Evaluation using a case study showed that the FDA provided necessary guidelines for developing an implementation that produced feedbackdriven learning analytics. Data preparation transformed unstructured data into a suitable representation for effective analysis. Cohorts within narrative feedback responses were identified using the k-means clustering algorithm and latent Dirichlet allocation. Logistic regression and support vector machines were applied as predictive models and trained using extracted quantitative markers to predict academic success. , Thesis (MSc) -- Faculty of Science, School of Computer Science, Mathematics, Physics and Statistics, 2023
- Full Text:
- Date Issued: 2023-12
An exploration of stakeholder perceptions of the quality of teaching and learning in higher education
- Authors: Jackson,Linda Grace
- Date: 2023-12
- Subjects: Quality assurance --Education (Higher)-- South Africa , Teaching and learning – Nelson Mandela University , Quality education—South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62464 , vital:72757
- Description: Quality in higher education is a complex and evolving concept that has been a subject of measurement, assurance and promotion in universities globally for the past three decades. However, its precise definition remains elusive due to its fluid nature, influenced by various contextual factors and stakeholder perspectives. This study explored the concepts of quality teaching and quality learning within the specific context of Nelson Mandela University, focusing on two critical internal stakeholder groups, lecturers and students. By maintaining a constant context, the study sought to gain a deeper understanding of how these stakeholders perceived and contributed to the overall quality of education at the institution. Defining quality in higher education (HE) is important, as it directly impacts on the evaluation processes within educational institutions. Presently, most Higher Education Institutions (HEIs) assess quality using tangible inputs and outputs, resulting in a quantifiable representation of quality. Despite this approach, realistically, the anticipated improvements in the quality of teaching and learning are not apparent, leading to concerns about graduate readiness for the demands of the workforce. This situation raises imperative questions about the quality of teaching and learning within HEIs, necessitating a response to address this issue. This study used the conceptual model Schindler et al. (2015) developed to investigate stakeholder perceptions of quality teaching and quality learning in higher education (HE). The research followed a novel perspective by uncoupling quality in HE from the prevailing neoliberal approach and considering quality in HE within social inclusion interventions (Gidley et al., 2010a) already in place in HE settings. The research methodology expanded on social inclusion theory and employed a qualitative, participative and visual approach adapted from Mmogo-method®, an indigenous method. The research design fostered active participation from the participants, who assumed the role of co-researchers. Participants constructed their answers to the research question using unstructured materials, subsequently sharing, explaining, and interpreting their viewpoints within the group setting. , Thesis (PhD) -- Faculty of Education, School of teaching and learning, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Jackson,Linda Grace
- Date: 2023-12
- Subjects: Quality assurance --Education (Higher)-- South Africa , Teaching and learning – Nelson Mandela University , Quality education—South Africa
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62464 , vital:72757
- Description: Quality in higher education is a complex and evolving concept that has been a subject of measurement, assurance and promotion in universities globally for the past three decades. However, its precise definition remains elusive due to its fluid nature, influenced by various contextual factors and stakeholder perspectives. This study explored the concepts of quality teaching and quality learning within the specific context of Nelson Mandela University, focusing on two critical internal stakeholder groups, lecturers and students. By maintaining a constant context, the study sought to gain a deeper understanding of how these stakeholders perceived and contributed to the overall quality of education at the institution. Defining quality in higher education (HE) is important, as it directly impacts on the evaluation processes within educational institutions. Presently, most Higher Education Institutions (HEIs) assess quality using tangible inputs and outputs, resulting in a quantifiable representation of quality. Despite this approach, realistically, the anticipated improvements in the quality of teaching and learning are not apparent, leading to concerns about graduate readiness for the demands of the workforce. This situation raises imperative questions about the quality of teaching and learning within HEIs, necessitating a response to address this issue. This study used the conceptual model Schindler et al. (2015) developed to investigate stakeholder perceptions of quality teaching and quality learning in higher education (HE). The research followed a novel perspective by uncoupling quality in HE from the prevailing neoliberal approach and considering quality in HE within social inclusion interventions (Gidley et al., 2010a) already in place in HE settings. The research methodology expanded on social inclusion theory and employed a qualitative, participative and visual approach adapted from Mmogo-method®, an indigenous method. The research design fostered active participation from the participants, who assumed the role of co-researchers. Participants constructed their answers to the research question using unstructured materials, subsequently sharing, explaining, and interpreting their viewpoints within the group setting. , Thesis (PhD) -- Faculty of Education, School of teaching and learning, 2023
- Full Text:
- Date Issued: 2023-12
Assessing land degradation and the effectiveness of calcrete bontveld rehabilitation in a grassridge PPC cement mining area using multi-sensor remotely sensed data and machine learning techniques
- Authors: Mpisane, Khanyisa
- Date: 2023-12
- Subjects: Land degradation -- South Africa , Environmental degradation , Mines and mineral resources -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62527 , vital:72821
- Description: This study uses multi-temporal remote sensing data to spatially visualise and quantify land degradation due to mining as well as Calcrete Bontveld rehabilitation at the Grassridge PPC Cement mine, Gqeberha formerly known as Port Elizabeth in the Eastern Cape, South Africa. Botanical field data is also used to verify the suasses of rehabilitation in the area. SPOT-6 and Landsat multi-spectral images were compared, and Support Vector Machine and Random Forest algorithms were used for classification in order to determine which yields more accurate results for a limestone mine. Support Vector Machine analysis using SPOT-6 images yielded the best results. This was due to the high spatial resolution of SPOT-6 compared to Landsat and Support Vector Machine classifier was able to classify images with fewer training points compared to Random Forest. The spatio-temporal land cover change at the mine was then determined between the years 2000, 2015 and 2020. Land cover classification is useful for monitoring land degradation and, in this case, was able to show the extent of rehabilitation success. For the year 2020, a 17% area was rehabilitated; however, the algorithm could not distinguish between unmined Calcrete Bontveld matrix and rehabilitation sites that were older than five years. The performed change detection also showed that 29.50% of unmined Calcrete Bontveld matrix had changed to “mature rehabilitation” (rehabilitation sites older than five years). Again, for this percentage in some areas the algorithm could not distinguish between the unmined Calcrete Bontveld matrix and rehabilitation sites that were older than five years due to high similarities between the two land cover types. Area changes of the different land cover classes could also be used to demonstrate how rehabilitation areas have matured over time and lead to the conclusion that most of the Calcrete Bontveld which was mined, has over the years been successfully rehabilitated. Vegetation analysis was conducted to further validate the rehabilitation success of Calcrete Bontveld matrix. Multivariant Detrended Correspondent Analysis showed that rehabilitation sites which were younger than five years (2–year-old rehabilitation plots that were sampled) had great dissimilarity to the natural unmined Calcrete Bontveld matrix and that rehabilitation sites older than five years, in this case 16–years older, had high similarity and resemblance to natural unmined Calcrete Bontveld matrix and therefore could be considered as being mature. This was a more definitive assessment as it considers all aspects of the vegetation. Species cover and species richness also showed that Calcrete Bontveld matrix rehabilitation sites which have been rehabilitated for more than 5 years had greater similarity to natural unmined vegetation compared to areas that have been rehabilitated for less than five years. This study, therefore, demonstrates that due to the high similarity between mature rehabilitation sites and unmined Calcrete Bontveld, rehabilitation has been successful. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Mpisane, Khanyisa
- Date: 2023-12
- Subjects: Land degradation -- South Africa , Environmental degradation , Mines and mineral resources -- South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62527 , vital:72821
- Description: This study uses multi-temporal remote sensing data to spatially visualise and quantify land degradation due to mining as well as Calcrete Bontveld rehabilitation at the Grassridge PPC Cement mine, Gqeberha formerly known as Port Elizabeth in the Eastern Cape, South Africa. Botanical field data is also used to verify the suasses of rehabilitation in the area. SPOT-6 and Landsat multi-spectral images were compared, and Support Vector Machine and Random Forest algorithms were used for classification in order to determine which yields more accurate results for a limestone mine. Support Vector Machine analysis using SPOT-6 images yielded the best results. This was due to the high spatial resolution of SPOT-6 compared to Landsat and Support Vector Machine classifier was able to classify images with fewer training points compared to Random Forest. The spatio-temporal land cover change at the mine was then determined between the years 2000, 2015 and 2020. Land cover classification is useful for monitoring land degradation and, in this case, was able to show the extent of rehabilitation success. For the year 2020, a 17% area was rehabilitated; however, the algorithm could not distinguish between unmined Calcrete Bontveld matrix and rehabilitation sites that were older than five years. The performed change detection also showed that 29.50% of unmined Calcrete Bontveld matrix had changed to “mature rehabilitation” (rehabilitation sites older than five years). Again, for this percentage in some areas the algorithm could not distinguish between the unmined Calcrete Bontveld matrix and rehabilitation sites that were older than five years due to high similarities between the two land cover types. Area changes of the different land cover classes could also be used to demonstrate how rehabilitation areas have matured over time and lead to the conclusion that most of the Calcrete Bontveld which was mined, has over the years been successfully rehabilitated. Vegetation analysis was conducted to further validate the rehabilitation success of Calcrete Bontveld matrix. Multivariant Detrended Correspondent Analysis showed that rehabilitation sites which were younger than five years (2–year-old rehabilitation plots that were sampled) had great dissimilarity to the natural unmined Calcrete Bontveld matrix and that rehabilitation sites older than five years, in this case 16–years older, had high similarity and resemblance to natural unmined Calcrete Bontveld matrix and therefore could be considered as being mature. This was a more definitive assessment as it considers all aspects of the vegetation. Species cover and species richness also showed that Calcrete Bontveld matrix rehabilitation sites which have been rehabilitated for more than 5 years had greater similarity to natural unmined vegetation compared to areas that have been rehabilitated for less than five years. This study, therefore, demonstrates that due to the high similarity between mature rehabilitation sites and unmined Calcrete Bontveld, rehabilitation has been successful. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Assessing the effectiveness of smart solutions on potable water in rural areas within Ngqushwa local municipality
- Authors: Fodo, Portia Noluthando
- Date: 2023-12
- Subjects: Potable water -- tap water , water infrastructure
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63298 , vital:73245
- Description: Providing potable water is a critical reposition towards achieving the Sustainable Development Goal (SDG) 6, to ensure the availability and sustainable management of water and sanitation for all. In addition, the use of smart solutions facilitates towards guaranteeing smart cities aligned with SDG11 which is aimed at making cities and human settlements inclusive, secure, resilient and viable. Access to potable water is a challenging issue in most rural areas as these areas were affected by the Apartheid regime where services were distributed according to the colour of the skin. In rural areas where many black people reside, the challenge of service delivery still exists. Ngqushwa Municipality is faced with several trials in the management of water, including water scarcity, lack of water infrastructure as well as illegal water connections. Despite more than 25 years of democracy, rural dwellers in Ngqushwa Municipality still suffer from a deficiency of access to potable water, which results in other health problems, such as Cholera. This study was aimed at assessing the role of smart solutions in the effective management of potable water in rural areas in Ngqushwa Local Municipality. The objectives to be achieved include identification of the policies that support the implementation of smart solutions in the provision of potable water in Ngqushwa Local Municipality, as well as determining the opportunities and challenges associated with smart solutions in the delivery of potable water. Moreover, identifying the existing difficulties affecting the execution of smart solutions in the delivery of potable water, along with developing recommendations on how smart solutions can effectively be put into operation in rural areas to control water. A qualitative research approach was applied as the chosen research methodology most appropriate to achieving the objectives of the research study. Data was collected using secondary sources and was analysed using thematic content analysis. The study revealed that opportunities available include accurate billing, smart metering and information availability. Furthermore, the obstacles included capacity constraints, cost factors and resistance to change. The investigation recommended, inter alia, that the municipality should accurately train its employees on matters relating to change management and establish effective debt controlling mechanisms to enhance water supervision in rural areas. , Thesis (MA) -- Faculty of Humanities, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Fodo, Portia Noluthando
- Date: 2023-12
- Subjects: Potable water -- tap water , water infrastructure
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63298 , vital:73245
- Description: Providing potable water is a critical reposition towards achieving the Sustainable Development Goal (SDG) 6, to ensure the availability and sustainable management of water and sanitation for all. In addition, the use of smart solutions facilitates towards guaranteeing smart cities aligned with SDG11 which is aimed at making cities and human settlements inclusive, secure, resilient and viable. Access to potable water is a challenging issue in most rural areas as these areas were affected by the Apartheid regime where services were distributed according to the colour of the skin. In rural areas where many black people reside, the challenge of service delivery still exists. Ngqushwa Municipality is faced with several trials in the management of water, including water scarcity, lack of water infrastructure as well as illegal water connections. Despite more than 25 years of democracy, rural dwellers in Ngqushwa Municipality still suffer from a deficiency of access to potable water, which results in other health problems, such as Cholera. This study was aimed at assessing the role of smart solutions in the effective management of potable water in rural areas in Ngqushwa Local Municipality. The objectives to be achieved include identification of the policies that support the implementation of smart solutions in the provision of potable water in Ngqushwa Local Municipality, as well as determining the opportunities and challenges associated with smart solutions in the delivery of potable water. Moreover, identifying the existing difficulties affecting the execution of smart solutions in the delivery of potable water, along with developing recommendations on how smart solutions can effectively be put into operation in rural areas to control water. A qualitative research approach was applied as the chosen research methodology most appropriate to achieving the objectives of the research study. Data was collected using secondary sources and was analysed using thematic content analysis. The study revealed that opportunities available include accurate billing, smart metering and information availability. Furthermore, the obstacles included capacity constraints, cost factors and resistance to change. The investigation recommended, inter alia, that the municipality should accurately train its employees on matters relating to change management and establish effective debt controlling mechanisms to enhance water supervision in rural areas. , Thesis (MA) -- Faculty of Humanities, 2023
- Full Text:
- Date Issued: 2023-12
Assessing the effectiveness of the planning, utilisation and implementation of the electronic human resource management strategy: a case of the department of home affairs in the Eastern Cape
- Authors: Dyan, Margaret Nombuyiselo
- Date: 2023-12
- Subjects: Personnel management , Home Affairs -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63287 , vital:73244
- Description: This study assessed the effectiveness of planning, implementing and utilising the electronic human resource management (e-HRM) strategy within the King William’s Town (KWT) Department of Home Affairs (DHA) in the Eastern Cape Province (EC) of South Africa (SA). E-HRM emerged because of the advent of technology. Many organisations use information technology to optimise the performance of both the employees and the organisation. Thus, this technology has been incorporated into organisations’ human resource functions, taking advantage of the latest technology to deliver an online real-time human resource management (HRM) solution. Therefore, this study sought to assess the e-HRM strategy's effectiveness within the KWT DHA. The technology acceptance model was adopted as a theoretical framework for the study to explain the adoption of the e-HRM strategy. A qualitative research approach using a case study research design was used for this study. Non-probability purposive sampling and convenience sampling were used to identify participants for the study. These participants provided the information needed to answer the research questions. The data was collected using in-depth interviews with the participants. The data was then analysed using thematic analysis following Braun and Clarke’s guidelines (2006). The study results revealed that implementing the e-HRM strategy within KWT DHA proves to be effective and efficient. The strategy’s implementation has been associated with improved performance of the KWT DHA in the Eastern Cape. It also saves time and ensures that HR information is accessed easily. The study also found barriers to the planning, implementation and utilisation of the e-HRM strategy, including a lack of skills and knowledge and resource constraints. The study also found that the current e-HRM policies are not fully functional. The study recommends continuous personnel training regarding the strategy, maximising the use of the e-HRM strategy and addressing the resource challenges. , Thesis (MA) -- Faculty of Humanities, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Dyan, Margaret Nombuyiselo
- Date: 2023-12
- Subjects: Personnel management , Home Affairs -- Eastern Cape
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63287 , vital:73244
- Description: This study assessed the effectiveness of planning, implementing and utilising the electronic human resource management (e-HRM) strategy within the King William’s Town (KWT) Department of Home Affairs (DHA) in the Eastern Cape Province (EC) of South Africa (SA). E-HRM emerged because of the advent of technology. Many organisations use information technology to optimise the performance of both the employees and the organisation. Thus, this technology has been incorporated into organisations’ human resource functions, taking advantage of the latest technology to deliver an online real-time human resource management (HRM) solution. Therefore, this study sought to assess the e-HRM strategy's effectiveness within the KWT DHA. The technology acceptance model was adopted as a theoretical framework for the study to explain the adoption of the e-HRM strategy. A qualitative research approach using a case study research design was used for this study. Non-probability purposive sampling and convenience sampling were used to identify participants for the study. These participants provided the information needed to answer the research questions. The data was collected using in-depth interviews with the participants. The data was then analysed using thematic analysis following Braun and Clarke’s guidelines (2006). The study results revealed that implementing the e-HRM strategy within KWT DHA proves to be effective and efficient. The strategy’s implementation has been associated with improved performance of the KWT DHA in the Eastern Cape. It also saves time and ensures that HR information is accessed easily. The study also found barriers to the planning, implementation and utilisation of the e-HRM strategy, including a lack of skills and knowledge and resource constraints. The study also found that the current e-HRM policies are not fully functional. The study recommends continuous personnel training regarding the strategy, maximising the use of the e-HRM strategy and addressing the resource challenges. , Thesis (MA) -- Faculty of Humanities, 2023
- Full Text:
- Date Issued: 2023-12
Assessing the effects of fish stock management on Cape gannet foraging behaviour in South Africa
- Strydom, Zanri, Grémillet, David, Pichegru, Lorien
- Authors: Strydom, Zanri , Grémillet, David , Pichegru, Lorien
- Date: 2023-12
- Subjects: Gannets -- South Africa , Birds of prey -- Behavior -- South Africa , Fish stock assessment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62622 , vital:72887
- Description: Seabirds are one of the most threatened groups of birds under both marine and terrestrial pressures. Among seabirds, the Cape gannet Morus capensis is a southern African endemic species facing several pressures of anthropogenic origin, including competition with industrial fisheries on small pelagic fish stocks. Cape gannets, being a long-lived species that is sensitive to environmental changes, are sentinels of change in oceanic environments granting it important to understand which factors influence their foraging behaviour and breeding outputs. For example, factors like age can result in a loss of physical capabilities which can lead to behavioral compensation and subsequent changes in chick provisioning rates and amounts. With the current fisheries management the fish stocks are continually decreasing, indicating the importance of an updated fine-scale assessment on the spatiotemporal overlap between foraging gannets and fisheries. The first objective of this thesis was to determine the influence of adult Cape gannets’ age and sex on their foraging characteristics and energy expenditure during foraging. I equipped chick-rearing Cape gannets of known age and sex with a 3D accelerometer and GPS device. Foraging effort (trip duration, foraging path and maximum distance to the nest) did not differ between sexes nor with age in Cape gannets. Both sexes rested less on the water with age. Aging females also spent more time in flight than males. The age- and sexual differences in energy expenditure prevalent in our study might reflect niche and/or risk partitioning strategies to ensure adequate provisioning to the chick. The second objective of this thesis was to determine the influence of fisheries catch rates, sardine and anchovy biomass, and adult foraging effort on chick growth rates in Cape gannets, using a long-term dataset collected between 2005 and 2020 on Malgas Island. I equipped chick-rearing adults with a GPS device and I weighed the chicks for between 3 to 6 increments to calculate the average daily mass increment. Of all the variables, foraging trip duration was the main determinant of daily growth rates, with chicks benefitting from parents’ shorter foraging trip durations. Chicks tended to grow slower when fisheries catch of sardine and anchovy were higher, possibly an effect of competition with fisheries. Chicks also grew faster when fish biomass was higher. This long-term monitoring demonstrated the possible effect of food competition between Cape gannets and fisheries, with negative impacts on gannet fitness as determined via chick growth rates. The third objective of this thesis was to determine the influence of both the biomass and fisheries catch rates of sardine and anchovy on Cape gannet foraging effort at a spatial and temporal scale. This was achieved by equipping a total of 668 chick-rearing Cape gannets with a GPS device. With an increase in fisheries catch there was an increase in the birds’ foraging effort. To reduce competition between the gannets and fisheries, the gannets’ core foraging areas seldomly overlapped with the fisheries catch locations, at the cost of the gannets’ increased foraging effort. One method to halt the Cape gannet population decline would be to conserve the fish resources close to the breeding colonies. This would reduce the birds’ foraging whereby increasing their fitness. Safeguarding small pelagic fish to ensure the perseverance of the remaining Benguela seabird populations, would lead to preserving the Benguela marine ecosystem as a whole. My study provided new insight into effects of fish stock management on Cape gannet foraging behaviour in South Africa, and the need for adequate management to ensure population persistence. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Strydom, Zanri , Grémillet, David , Pichegru, Lorien
- Date: 2023-12
- Subjects: Gannets -- South Africa , Birds of prey -- Behavior -- South Africa , Fish stock assessment
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62622 , vital:72887
- Description: Seabirds are one of the most threatened groups of birds under both marine and terrestrial pressures. Among seabirds, the Cape gannet Morus capensis is a southern African endemic species facing several pressures of anthropogenic origin, including competition with industrial fisheries on small pelagic fish stocks. Cape gannets, being a long-lived species that is sensitive to environmental changes, are sentinels of change in oceanic environments granting it important to understand which factors influence their foraging behaviour and breeding outputs. For example, factors like age can result in a loss of physical capabilities which can lead to behavioral compensation and subsequent changes in chick provisioning rates and amounts. With the current fisheries management the fish stocks are continually decreasing, indicating the importance of an updated fine-scale assessment on the spatiotemporal overlap between foraging gannets and fisheries. The first objective of this thesis was to determine the influence of adult Cape gannets’ age and sex on their foraging characteristics and energy expenditure during foraging. I equipped chick-rearing Cape gannets of known age and sex with a 3D accelerometer and GPS device. Foraging effort (trip duration, foraging path and maximum distance to the nest) did not differ between sexes nor with age in Cape gannets. Both sexes rested less on the water with age. Aging females also spent more time in flight than males. The age- and sexual differences in energy expenditure prevalent in our study might reflect niche and/or risk partitioning strategies to ensure adequate provisioning to the chick. The second objective of this thesis was to determine the influence of fisheries catch rates, sardine and anchovy biomass, and adult foraging effort on chick growth rates in Cape gannets, using a long-term dataset collected between 2005 and 2020 on Malgas Island. I equipped chick-rearing adults with a GPS device and I weighed the chicks for between 3 to 6 increments to calculate the average daily mass increment. Of all the variables, foraging trip duration was the main determinant of daily growth rates, with chicks benefitting from parents’ shorter foraging trip durations. Chicks tended to grow slower when fisheries catch of sardine and anchovy were higher, possibly an effect of competition with fisheries. Chicks also grew faster when fish biomass was higher. This long-term monitoring demonstrated the possible effect of food competition between Cape gannets and fisheries, with negative impacts on gannet fitness as determined via chick growth rates. The third objective of this thesis was to determine the influence of both the biomass and fisheries catch rates of sardine and anchovy on Cape gannet foraging effort at a spatial and temporal scale. This was achieved by equipping a total of 668 chick-rearing Cape gannets with a GPS device. With an increase in fisheries catch there was an increase in the birds’ foraging effort. To reduce competition between the gannets and fisheries, the gannets’ core foraging areas seldomly overlapped with the fisheries catch locations, at the cost of the gannets’ increased foraging effort. One method to halt the Cape gannet population decline would be to conserve the fish resources close to the breeding colonies. This would reduce the birds’ foraging whereby increasing their fitness. Safeguarding small pelagic fish to ensure the perseverance of the remaining Benguela seabird populations, would lead to preserving the Benguela marine ecosystem as a whole. My study provided new insight into effects of fish stock management on Cape gannet foraging behaviour in South Africa, and the need for adequate management to ensure population persistence. , Thesis (PhD) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Assessment of knowledge, attitudes, practices and the prevalence of intestinal parasites in Sarah Baartman District, Eastern Cape
- Authors: Mrwebi, Sisanda
- Date: 2023-12
- Subjects: Intestinal parasites , Knowledge Attitudes and Practices , transmitted helminths
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62924 , vital:73070
- Description: ntestinal parasites also known as parasitic worms are one of the common water, soil and feacal transmitted infections of public importance in the world. This study evaluated the Knowledge, Attitudes and Practices (KAP) of public workers comprising EPWP and CWP general workers on intestinal parasites in a selected municipality in the study area . Additionally, using secondary data, the researcher established the prevalence of intestinal parasites in Sarah Baartman District Municipality (SBDM) from 2012 to 2020. Method: The study made use of a quantitative, cross-sectional research design resembling a study by S.D. Hambury .A structured questionnaire, closed-ended, telephonically-administered questionnaire was used to collect data from 160 Expanded Public Works Programme (EPWP) and Community Work Programme (CWP) general workers. Data on the prevalence was obtained from the SBDM National Health Laboratory Service (NHLS). Data was analysed using both inferential and descriptive statistics using SPSS software version 16.1, inferential statistics tests used were Chi2 square tests and p-value tests. Descriptive statistic tests used included frequency distributions, percentage, cumulative percent, and valid percent. Results: The participants’ overall awareness, attitudes and practices of the study were poor, 64.4% of the study participants had the correct knowledge about intestinal parasite infections. The age of study participants and who the participants thought was at risk of being infected by intestinal parasites had a non significant relationship (p>0.05). Gender and the responses to who is at risk of getting infected with intestinal parasites had a statistically significant (p<0.05) relationship. Intestinal parasite prevalence from 2012 to 2020 in SBDM was 46.37% which means it was close to half of the sampled population. Males had the highest prevalence as compared to females, with a prevalence of 53.1% xvi in males and 46.9% in females. The highest disease infection was found between ages one and six years. Conclusion: The researcher concluded that the overall awareness, attitudes and practices on intestinal parasites in SBDM were poor. The intestinal parasites present in SBDM were Cytoisospora belli (35.4%) and Giardia lamblia (35.4%), Ascaris lumbricoides (17.7%), Trichuris trichiura (3%), and Taenia species (2%). The study also revealed that the prevalence of intestinal parasites was low from 2012 to 2020. Recommendations were made with an emphasis on education to increase disease prevention and control awareness. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Mrwebi, Sisanda
- Date: 2023-12
- Subjects: Intestinal parasites , Knowledge Attitudes and Practices , transmitted helminths
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62924 , vital:73070
- Description: ntestinal parasites also known as parasitic worms are one of the common water, soil and feacal transmitted infections of public importance in the world. This study evaluated the Knowledge, Attitudes and Practices (KAP) of public workers comprising EPWP and CWP general workers on intestinal parasites in a selected municipality in the study area . Additionally, using secondary data, the researcher established the prevalence of intestinal parasites in Sarah Baartman District Municipality (SBDM) from 2012 to 2020. Method: The study made use of a quantitative, cross-sectional research design resembling a study by S.D. Hambury .A structured questionnaire, closed-ended, telephonically-administered questionnaire was used to collect data from 160 Expanded Public Works Programme (EPWP) and Community Work Programme (CWP) general workers. Data on the prevalence was obtained from the SBDM National Health Laboratory Service (NHLS). Data was analysed using both inferential and descriptive statistics using SPSS software version 16.1, inferential statistics tests used were Chi2 square tests and p-value tests. Descriptive statistic tests used included frequency distributions, percentage, cumulative percent, and valid percent. Results: The participants’ overall awareness, attitudes and practices of the study were poor, 64.4% of the study participants had the correct knowledge about intestinal parasite infections. The age of study participants and who the participants thought was at risk of being infected by intestinal parasites had a non significant relationship (p>0.05). Gender and the responses to who is at risk of getting infected with intestinal parasites had a statistically significant (p<0.05) relationship. Intestinal parasite prevalence from 2012 to 2020 in SBDM was 46.37% which means it was close to half of the sampled population. Males had the highest prevalence as compared to females, with a prevalence of 53.1% xvi in males and 46.9% in females. The highest disease infection was found between ages one and six years. Conclusion: The researcher concluded that the overall awareness, attitudes and practices on intestinal parasites in SBDM were poor. The intestinal parasites present in SBDM were Cytoisospora belli (35.4%) and Giardia lamblia (35.4%), Ascaris lumbricoides (17.7%), Trichuris trichiura (3%), and Taenia species (2%). The study also revealed that the prevalence of intestinal parasites was low from 2012 to 2020. Recommendations were made with an emphasis on education to increase disease prevention and control awareness. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
Case-based research on the fedup model for self-help housing
- Authors: Qumbisa, Nolwazi
- Date: 2023-12
- Subjects: Community participation , Human settlements , Informal settlements
- Language: English
- Type: doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/62199 , vital:72007
- Description: In South Africa, the government subsidises the building of starter homes to meet the demand for housing for people with lower incomes. However, it is necessary for the state to revise its efforts to meet the demand for housing in the country. Self-help housing is a model that can be used as an alternative to state housing subsidies. The present research study investigates the essential aspects of sustainable self-help housing in the central region of South Africa. The present study aimed to address the central research topic by eliciting responses from participants: How can self-help provision become sustainable in the central region of South Africa? In response to the question, an effective self-help housing support model was developed, the aim of which is to outline how self-help housing projects could be improved. The literature findings demonstrate the potential of this model as a viable alternative to the existing housing delivery mechanism in South Africa. This assertion is supported by a study of self-help housing trajectories and an examination of relevant South African housing policies. However, there has been a lack of emphasis on the simplification of current models to accommodate the needs of implementers, government entities, and beneficiaries of self-help housing initiatives. This study aimed to address the highlighted gaps by utilising a qualitative methodology and drawing upon the data obtained. The data collection techniques included semi-structured interviews, structured observations, and focus-group discussions. A total of 25 semi-structured interviews were conducted with key stakeholders in human settlements, while the focus-group discussions involved 50 participants. A total of 5 focus group discussions were conducted with each group consisting of 10 participants. Moreover, the researcher conducted a document analysis, observations, and questionnaire survey. The data collected were analysed thematically. The results revealed that there are still challenges with implementing self-help housing. Moreover, the results are attributed mainly to a mismatch of the roles and responsibilities and not understanding the Enhanced People’s Housing Process (EPHP) policy. The principal contribution of the thesis is that housing policies, programmes and sector plans must encourage beneficiaries to play an active role. This study found that weak or unclear project vi specifications lead to contractor misunderstandings or discrepancies in housing project implementation, resulting in poor-quality work or delays. The conventional contractor-driven housing-delivery model also has issues like poor construction, corruption and mismanagement, profit-driven contractors, high contractor rates, project delays/incomplete projects, illegal occupation of incomplete projects, riots and disputes, ineffective project specifications, and beneficiary disengagement. In this study, it is demonstrated how a positive social impact on housing could be the outcome of an improved self-help approach. Consequently, the research suggests the adoption of an effective self-help housing support model, which may effectively address the challenges posed by informal settlements while enhancing the execution of self-help housing projects. The model has the potential to make contemporary contributions to the public housing policy model in South Africa. This study contributes to the broader discourse on sustainable housing alternatives, providing insights into the various obstacles, potential advantages, and recommended strategies within the realm of selfhelp housing. The study's qualitative approach facilitated a comprehensive examination of the lived experiences and viewpoints of diverse stakeholders. This yielded valuable insights that can inform policymakers, practitioners, and communities in their efforts to improve the sustainability of self-help housing solutions in the central region of South Africa. , Thesis (PhD) -- Engineering, Built Environment and Technology, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Qumbisa, Nolwazi
- Date: 2023-12
- Subjects: Community participation , Human settlements , Informal settlements
- Language: English
- Type: doctoral's theses , text
- Identifier: http://hdl.handle.net/10948/62199 , vital:72007
- Description: In South Africa, the government subsidises the building of starter homes to meet the demand for housing for people with lower incomes. However, it is necessary for the state to revise its efforts to meet the demand for housing in the country. Self-help housing is a model that can be used as an alternative to state housing subsidies. The present research study investigates the essential aspects of sustainable self-help housing in the central region of South Africa. The present study aimed to address the central research topic by eliciting responses from participants: How can self-help provision become sustainable in the central region of South Africa? In response to the question, an effective self-help housing support model was developed, the aim of which is to outline how self-help housing projects could be improved. The literature findings demonstrate the potential of this model as a viable alternative to the existing housing delivery mechanism in South Africa. This assertion is supported by a study of self-help housing trajectories and an examination of relevant South African housing policies. However, there has been a lack of emphasis on the simplification of current models to accommodate the needs of implementers, government entities, and beneficiaries of self-help housing initiatives. This study aimed to address the highlighted gaps by utilising a qualitative methodology and drawing upon the data obtained. The data collection techniques included semi-structured interviews, structured observations, and focus-group discussions. A total of 25 semi-structured interviews were conducted with key stakeholders in human settlements, while the focus-group discussions involved 50 participants. A total of 5 focus group discussions were conducted with each group consisting of 10 participants. Moreover, the researcher conducted a document analysis, observations, and questionnaire survey. The data collected were analysed thematically. The results revealed that there are still challenges with implementing self-help housing. Moreover, the results are attributed mainly to a mismatch of the roles and responsibilities and not understanding the Enhanced People’s Housing Process (EPHP) policy. The principal contribution of the thesis is that housing policies, programmes and sector plans must encourage beneficiaries to play an active role. This study found that weak or unclear project vi specifications lead to contractor misunderstandings or discrepancies in housing project implementation, resulting in poor-quality work or delays. The conventional contractor-driven housing-delivery model also has issues like poor construction, corruption and mismanagement, profit-driven contractors, high contractor rates, project delays/incomplete projects, illegal occupation of incomplete projects, riots and disputes, ineffective project specifications, and beneficiary disengagement. In this study, it is demonstrated how a positive social impact on housing could be the outcome of an improved self-help approach. Consequently, the research suggests the adoption of an effective self-help housing support model, which may effectively address the challenges posed by informal settlements while enhancing the execution of self-help housing projects. The model has the potential to make contemporary contributions to the public housing policy model in South Africa. This study contributes to the broader discourse on sustainable housing alternatives, providing insights into the various obstacles, potential advantages, and recommended strategies within the realm of selfhelp housing. The study's qualitative approach facilitated a comprehensive examination of the lived experiences and viewpoints of diverse stakeholders. This yielded valuable insights that can inform policymakers, practitioners, and communities in their efforts to improve the sustainability of self-help housing solutions in the central region of South Africa. , Thesis (PhD) -- Engineering, Built Environment and Technology, 2023
- Full Text:
- Date Issued: 2023-12
Characterization of the coastal Aquifer of Gqeberha, South Africa : Developing a conceptual understanding
- Authors: Vandala, Bamanye
- Date: 2023-12
- Subjects: Aquifers -- South Africa -- Port Elizabeth , Groundwater ecology , Hydrogeology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62710 , vital:72932
- Description: The aquifer systems in Gqeberha are poorly understood due to a lack of groundwater studies within the area, and this is particularly the case for the coastal aquifer of Gqeberha. Amidst the water crisis the city is currently facing, groundwater has become crucial, with over 1000 boreholes reportedly drilled in the coastal area, most of which are residential. This has resulted in the need to conduct more groundwater studies in the area and in Nelson Mandela Bay. This study presents a detailed hydrogeological characterization of the coastal aquifer of Gqeberha. This was achieved through the use of different techniques, which include field mapping, geophysics, hydrochemistry, and pumping test analysis. The work was done on the coastal seeps of the Algoa Group Formation and the fractured aquifer of the Peninsula Formation. The results through mapping indicated an abundance of folds, faults, and fractures which all have implications for groundwater flow. The majority of fractures are striking in the NE-SW and NW-SE directions. The pumping test analysis also indicated fractal flow with significant matrix flow resulting in a dual porosity system up to at least 200m in depth. The transmissivity and storativity values range from 6.78 – 44.5 m2/day and 0.0172 – 0.0325, respectively. This is highly dependent on the fracture interconnectivity, which varies across the area and is higher at shallow depths, as suggested by the geophysical profiles. Geophysical profiles indicate that the contact between the Algoa Group Formations and the Peninsula Formation results in coastal seeps due to the difference in hydraulic conductivities. The hydrochemical analysis suggests that the seeps generally have Na-Cl and Ca-Mg-Cl water types. The groundwater in the eastern area has a Ca-HCO3 water type, and the groundwater in the western region has a Ca-Mg-Cl water type, with the Chelsea-Noordhoek Fault system separating the two groundwater signatures. Groundwater at greater depths has a Na-Cl water type with higher TDS values. The chemical signatures seen are due to external factors, which include sea sprays, anthropogenic activities, rock-water processes, and possibly connate water in the Peninsula Formation aquifer. The findings of this study offer valuable insights into the present conditions of the aquifer in Gqeberha. This research serves as a foundational study that can provide a baseline for future hydrogeological investigations in the area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Vandala, Bamanye
- Date: 2023-12
- Subjects: Aquifers -- South Africa -- Port Elizabeth , Groundwater ecology , Hydrogeology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62710 , vital:72932
- Description: The aquifer systems in Gqeberha are poorly understood due to a lack of groundwater studies within the area, and this is particularly the case for the coastal aquifer of Gqeberha. Amidst the water crisis the city is currently facing, groundwater has become crucial, with over 1000 boreholes reportedly drilled in the coastal area, most of which are residential. This has resulted in the need to conduct more groundwater studies in the area and in Nelson Mandela Bay. This study presents a detailed hydrogeological characterization of the coastal aquifer of Gqeberha. This was achieved through the use of different techniques, which include field mapping, geophysics, hydrochemistry, and pumping test analysis. The work was done on the coastal seeps of the Algoa Group Formation and the fractured aquifer of the Peninsula Formation. The results through mapping indicated an abundance of folds, faults, and fractures which all have implications for groundwater flow. The majority of fractures are striking in the NE-SW and NW-SE directions. The pumping test analysis also indicated fractal flow with significant matrix flow resulting in a dual porosity system up to at least 200m in depth. The transmissivity and storativity values range from 6.78 – 44.5 m2/day and 0.0172 – 0.0325, respectively. This is highly dependent on the fracture interconnectivity, which varies across the area and is higher at shallow depths, as suggested by the geophysical profiles. Geophysical profiles indicate that the contact between the Algoa Group Formations and the Peninsula Formation results in coastal seeps due to the difference in hydraulic conductivities. The hydrochemical analysis suggests that the seeps generally have Na-Cl and Ca-Mg-Cl water types. The groundwater in the eastern area has a Ca-HCO3 water type, and the groundwater in the western region has a Ca-Mg-Cl water type, with the Chelsea-Noordhoek Fault system separating the two groundwater signatures. Groundwater at greater depths has a Na-Cl water type with higher TDS values. The chemical signatures seen are due to external factors, which include sea sprays, anthropogenic activities, rock-water processes, and possibly connate water in the Peninsula Formation aquifer. The findings of this study offer valuable insights into the present conditions of the aquifer in Gqeberha. This research serves as a foundational study that can provide a baseline for future hydrogeological investigations in the area. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Chemical analysis and biological activities of crude extracts and essential oil of selected medicinal plants from the Eastern Cape, South Africa, and Volta Region of Ghana
- Authors: Agbo, Irene Adzo
- Date: 2023-12
- Subjects: Medicinal plants , Lantana camara , Peptic ulcer -- Treatment , Traditional medicine - South Africa -- Eastern Cape , Traditional medicine -- Ghana
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62431 , vital:72728
- Description: Lantana camara and Khaya grandifoliola extracts are among many plants found traditionally effective for the treatment of wounds and ulcers. This study assessed the phytochemical content, isolation and identification of single compounds from methanol and ethyl acetate extracts of Lantana camara and Khaya grandifoliola. Further, the bioactivity testing including antioxidant, antimicrobial and cytoxicity of the extracts was done to confirm the wound healing potential discovered by the traditional healers. Materials and methods: Extraction was done successively using maceration method with 100 % ethyl acetate and 100 % methanol with a biomass-to-solvent ratio of 1:3 (w/v) to obtain L. camara ethyl acetate extracts of berry (ELB), flower (ELF) and leaf (ELL) and methanol extracts of MLB, MLF, MLL and K. grandifoliola ethyl acetate extracts of leaf (EKL), root (EKR) and stem bark (EKSB) and methanol extracts of MKL, MKR, MKSB respectively. L. camara leaf essential oil (EO) was extracted using the hydro-distillation method with a Clevenger apparatus. Total phytochemical content was assessed for each extract using spectrophotometric methods and a calibration curve of standards: bromocresol green method with atropine; Folin–Ciocalteu colorimetric method with gallic acid, aluminium chloride colorimetric method with quercetin and concentrated sulphuric acid chloroform with linalool for total alkaloid, phenolic, flavonoid and terpenoid contents respectively. Single compound isolation and purification was conducted using chromatographic techniques. Elucidation of single compounds was done using spectrometric method, high resolution- mass spectrometry, and one and two-dimensional (1D and 2D)-NMR. Stereochemistry of each compound was confirmed using electronic circular dichroism spectra. A Crystalline compound was identified by single crystal X-ray diffraction using CuKα-radiation. In vitro bioactivities were assessed with methods such as 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide, free radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl, inhibitory effect on nitric oxide production in lipopolysaccharide-activated RAW 264.7 macrophages, and 96-well plate micro dilution for cytotoxicity, ant-inflammatory and antimicrobial activity testing. Results: Methanol extracts of both plants retained high phytochemical concentrations of all the phytoconstituents investigated compared with the ethyl acetate extracts which retained lower concentrations. The results of the L. camara methanol extracts include; total alkaloid content (TAC) (2.05±0.18, 1.87±1.54 and 2.60±1.10 mg AEQ/100 mg); total phenolic content (TPC) (14.05±4.04, 34.59±3.01 and 18.58±1.87 mg GAEQ/100 mg); the total flavonoid content(TFC) of flower (12.45±1.87, 20.41±2.69 and mg QEQ/100 mg); total terpenoids (TTC) (20.74±2.34, 20.74±2.34 and 15.97±1.19 mg LIN EQ/100mg) of MLB, MLF and MLL respectively. Whereas that of the K. grandifoliola methanol extracts include; TAC (7.32±0.14,8.49±0.34, 10.67±0.22 mg AEQ/100 mg); TPC (37.49±1.40, 44.41±0.69, 53.57±1.50 mgGAEQ/100 mg); TFC (6.54±0.55, 9.58±0.89 and 10.26±0.92 mg QEQ/100 mg); TTC(10.16±1.41, 35.78±2.14 and 23.45±1.76 mg LIN EQ/100mg) of MKL, MKR and MKSB respectively. The major components of essential oil, out of the 71 constituents identified include Davanone D (32.91 %), Caryophyllene (5.07 %), Nerolidol 2 (3.56 %) and GermacreneD (3.13 %). Compounds 3.47 was isolated from the methanol extract of L. camara flowers. This compound is reported for the first time from the L. camara flower extract. Two compounds, compounds 4.23, and 4.26, were isolated from the methanol extract of K. grandifoliola roots, compound 4.22 was isolated from the ethyl acetate root extract while compounds 4.24 and 4.25 were isolated from the ethyl acetate stem bark extract as isomers in a mixture. Compounds 4.22 and 4.23 are reported from K. grandifoliola root for the first time. The isolated compounds (compounds 3.47 and 4.23) were nontoxic to the Vero cell line and this may contribute to possible stimulation of cell proliferation, promoting wound healing. Cytotoxicity describes extract virulence to Vero cell line. MLF and ELB were found nontoxic even at the highest concentration of 200 μg/mL. The MKSB and MKR, as well as the EKSB were nontoxic. Antioxidant activity results, described by the percentage inhibition in the DPPH assay, showed that MLF and MKSB had the highest antioxidant activities compared with the ascorbic acid standard, with IC50 of 38.68±5.09 and 37.03±11.95 μg/mL for L. camara and K. grandifoliola respectively. ELB exhibited a significant anti-inflammatory activity inhibiting NO• radical generation in the LPS-stimulated RAW 264.7 macrophages at concentration ranging from 50 and 100 μg/mL. EKSB and MKR showed significant anti-inflammatory activity at 100 and 200 μg/ml respectively. ELL and ELF demonstrated potent growth inhibition against S. pyogenes with an MIC value ≤ 0.125 mg/mL, while the MICs of the ELB and MLL were 0.5 mg/mL and 2 mg/mL respectively. MKSB and MKR and EKSB extract exhibited an effective growth inhibition against S. aureus with MIC of 1 mg/mL. The growth of S. pyogenes was supressed by both ethyl acetate and methanol extracts of all plant parts tested with MIC ranging from 0.25–2 mg/mL. Conclusion: The potent bioactivity shown in the results of the cytotoxicity, antioxidant activity, anti-inflammatory and antimicrobial activity testing, and the nontoxic singlecompounds of L. camara and K. grandifoliola extracts led to the conclusion that the two plants had wound healing potential. The study therefore confirmed their traditional uses for treatment of wounds. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Agbo, Irene Adzo
- Date: 2023-12
- Subjects: Medicinal plants , Lantana camara , Peptic ulcer -- Treatment , Traditional medicine - South Africa -- Eastern Cape , Traditional medicine -- Ghana
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62431 , vital:72728
- Description: Lantana camara and Khaya grandifoliola extracts are among many plants found traditionally effective for the treatment of wounds and ulcers. This study assessed the phytochemical content, isolation and identification of single compounds from methanol and ethyl acetate extracts of Lantana camara and Khaya grandifoliola. Further, the bioactivity testing including antioxidant, antimicrobial and cytoxicity of the extracts was done to confirm the wound healing potential discovered by the traditional healers. Materials and methods: Extraction was done successively using maceration method with 100 % ethyl acetate and 100 % methanol with a biomass-to-solvent ratio of 1:3 (w/v) to obtain L. camara ethyl acetate extracts of berry (ELB), flower (ELF) and leaf (ELL) and methanol extracts of MLB, MLF, MLL and K. grandifoliola ethyl acetate extracts of leaf (EKL), root (EKR) and stem bark (EKSB) and methanol extracts of MKL, MKR, MKSB respectively. L. camara leaf essential oil (EO) was extracted using the hydro-distillation method with a Clevenger apparatus. Total phytochemical content was assessed for each extract using spectrophotometric methods and a calibration curve of standards: bromocresol green method with atropine; Folin–Ciocalteu colorimetric method with gallic acid, aluminium chloride colorimetric method with quercetin and concentrated sulphuric acid chloroform with linalool for total alkaloid, phenolic, flavonoid and terpenoid contents respectively. Single compound isolation and purification was conducted using chromatographic techniques. Elucidation of single compounds was done using spectrometric method, high resolution- mass spectrometry, and one and two-dimensional (1D and 2D)-NMR. Stereochemistry of each compound was confirmed using electronic circular dichroism spectra. A Crystalline compound was identified by single crystal X-ray diffraction using CuKα-radiation. In vitro bioactivities were assessed with methods such as 3-[4,5-dimethylthiazole-2-yl]-2,5-diphenyltetrazolium bromide, free radical scavenging activity of 1,1-diphenyl-2-picrylhydrazyl, inhibitory effect on nitric oxide production in lipopolysaccharide-activated RAW 264.7 macrophages, and 96-well plate micro dilution for cytotoxicity, ant-inflammatory and antimicrobial activity testing. Results: Methanol extracts of both plants retained high phytochemical concentrations of all the phytoconstituents investigated compared with the ethyl acetate extracts which retained lower concentrations. The results of the L. camara methanol extracts include; total alkaloid content (TAC) (2.05±0.18, 1.87±1.54 and 2.60±1.10 mg AEQ/100 mg); total phenolic content (TPC) (14.05±4.04, 34.59±3.01 and 18.58±1.87 mg GAEQ/100 mg); the total flavonoid content(TFC) of flower (12.45±1.87, 20.41±2.69 and mg QEQ/100 mg); total terpenoids (TTC) (20.74±2.34, 20.74±2.34 and 15.97±1.19 mg LIN EQ/100mg) of MLB, MLF and MLL respectively. Whereas that of the K. grandifoliola methanol extracts include; TAC (7.32±0.14,8.49±0.34, 10.67±0.22 mg AEQ/100 mg); TPC (37.49±1.40, 44.41±0.69, 53.57±1.50 mgGAEQ/100 mg); TFC (6.54±0.55, 9.58±0.89 and 10.26±0.92 mg QEQ/100 mg); TTC(10.16±1.41, 35.78±2.14 and 23.45±1.76 mg LIN EQ/100mg) of MKL, MKR and MKSB respectively. The major components of essential oil, out of the 71 constituents identified include Davanone D (32.91 %), Caryophyllene (5.07 %), Nerolidol 2 (3.56 %) and GermacreneD (3.13 %). Compounds 3.47 was isolated from the methanol extract of L. camara flowers. This compound is reported for the first time from the L. camara flower extract. Two compounds, compounds 4.23, and 4.26, were isolated from the methanol extract of K. grandifoliola roots, compound 4.22 was isolated from the ethyl acetate root extract while compounds 4.24 and 4.25 were isolated from the ethyl acetate stem bark extract as isomers in a mixture. Compounds 4.22 and 4.23 are reported from K. grandifoliola root for the first time. The isolated compounds (compounds 3.47 and 4.23) were nontoxic to the Vero cell line and this may contribute to possible stimulation of cell proliferation, promoting wound healing. Cytotoxicity describes extract virulence to Vero cell line. MLF and ELB were found nontoxic even at the highest concentration of 200 μg/mL. The MKSB and MKR, as well as the EKSB were nontoxic. Antioxidant activity results, described by the percentage inhibition in the DPPH assay, showed that MLF and MKSB had the highest antioxidant activities compared with the ascorbic acid standard, with IC50 of 38.68±5.09 and 37.03±11.95 μg/mL for L. camara and K. grandifoliola respectively. ELB exhibited a significant anti-inflammatory activity inhibiting NO• radical generation in the LPS-stimulated RAW 264.7 macrophages at concentration ranging from 50 and 100 μg/mL. EKSB and MKR showed significant anti-inflammatory activity at 100 and 200 μg/ml respectively. ELL and ELF demonstrated potent growth inhibition against S. pyogenes with an MIC value ≤ 0.125 mg/mL, while the MICs of the ELB and MLL were 0.5 mg/mL and 2 mg/mL respectively. MKSB and MKR and EKSB extract exhibited an effective growth inhibition against S. aureus with MIC of 1 mg/mL. The growth of S. pyogenes was supressed by both ethyl acetate and methanol extracts of all plant parts tested with MIC ranging from 0.25–2 mg/mL. Conclusion: The potent bioactivity shown in the results of the cytotoxicity, antioxidant activity, anti-inflammatory and antimicrobial activity testing, and the nontoxic singlecompounds of L. camara and K. grandifoliola extracts led to the conclusion that the two plants had wound healing potential. The study therefore confirmed their traditional uses for treatment of wounds. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Dietary assessment of Cape Gannets (Morus capensis) and African Penguins (Spheniscus demersus) in Algoa Bay using molecular scatology
- Bowmaker - Falconer, Kezia, Von Der Heyden, Sophie
- Authors: Bowmaker - Falconer, Kezia , Von Der Heyden, Sophie
- Date: 2023-12
- Subjects: Gannets , Gannets -- Food , Sea birds -- South Africa -- Bird Island, Algoa Bay.
- Language: English
- Type: Master's theses
- Identifier: http://hdl.handle.net/10948/62420 , vital:72675
- Description: Seabirds are important marine sentinels, providing valuable information about ecosystem health and condition. Dietary studies of seabirds can inform on ecosystem functioning through identifying the condition and changes occurring in their surrounding environment. Dietary studies are also crucial as they can identify threats that seabirds face. Until recently, the diets of southern African endemic and Endangered Cape Gannets Morus capensis and African Penguins Spheniscus demersus were solely investigated through stomach content analyses, which allows for the identification and quantification of prey remains. To overcome some of the limitations associated with stomach content analysis, stable isotope and fatty acid analyses were proposed. However, these methods still require bird handling and thus impose some stress on the birds. DNA metabarcoding of faecal matter shows promise as a completely noninvasive method for seabird dietary studies. This thesis first examined whether DNA metabarcoding could be used to determine the diet of Cape Gannet and African Penguin breeding in Algoa Bay, South Africa. Then, this method was used to investigate the influence of intrinsic (both seabird species) and extrinsic (African Penguins) factors on the diet of the two seabird species. For the first data chapter, stomach content samples and faecal matter were collected concurrently from breeding Cape Gannets and African Penguins on Bird Island. DNA was successfully extracted from most faecal matter samples and the primers (18S_SSU, 16S_Fish) used for group, taxa and fish prey identification allowed amplification of prey DNA for both study species. A similar piscivorous diet was determined by both dietary methods for Cape Gannets with Sardine Sardinops sagax and Atlantic Saury Scomberesox saurus dominating the diet. Sardine also dominated the African Penguin diet in both dietary methods. In addition, DNA metabarcoding in African Penguins revealed a more diverse diet compared to the one determined by stomach content analysis. This was likely due to the limitations on the allowed number of stomach content samples to be collected for that Endangered species. Non-invasive DNA metabarcoding of faecal matter was then used to investigate whether the diet varied with breeding stages (incubation, chick-rearing) and age classes (chick-rearing adults, chicks) in both seabird species, but also breeding colonies (Algoa Bay: Bird Island, St Croix Island) in African Penguins. DNA metabarcoding revealed that breeding stages influenced the diet of Cape Gannets and African Penguins on Bird Island where prey species diversity was greater for incubating adults. On the contrary, the diet of incubating and chick-rearing penguins on St Croix Island was similar. When comparing the diet of African Penguins between Bird Island and St Croix Island, there was an increased overlap in diet composition between incubating and chick-rearing adults on St Croix Island when compared to Bird Island. Importantly, DNA metabarcoding indicated an increase in fishery interactions in Algoa Bay, particularly for Cape Gannets and the hake Merluccius spp. fishery, where the contribution of hake to chick-rearing adults and chick diet was considerably greater than incubating adult diet. In this study, I showed that DNA metabarcoding of faecal matter provides an opportunity for non-invasive dietary studies in two southern African endemic and Endangered seabird species. Incorporating non-invasive methods as a complement to other dietary methods for monitoring seabird trophic ecology is crucial when considering the worsening status of several seabird species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Bowmaker - Falconer, Kezia , Von Der Heyden, Sophie
- Date: 2023-12
- Subjects: Gannets , Gannets -- Food , Sea birds -- South Africa -- Bird Island, Algoa Bay.
- Language: English
- Type: Master's theses
- Identifier: http://hdl.handle.net/10948/62420 , vital:72675
- Description: Seabirds are important marine sentinels, providing valuable information about ecosystem health and condition. Dietary studies of seabirds can inform on ecosystem functioning through identifying the condition and changes occurring in their surrounding environment. Dietary studies are also crucial as they can identify threats that seabirds face. Until recently, the diets of southern African endemic and Endangered Cape Gannets Morus capensis and African Penguins Spheniscus demersus were solely investigated through stomach content analyses, which allows for the identification and quantification of prey remains. To overcome some of the limitations associated with stomach content analysis, stable isotope and fatty acid analyses were proposed. However, these methods still require bird handling and thus impose some stress on the birds. DNA metabarcoding of faecal matter shows promise as a completely noninvasive method for seabird dietary studies. This thesis first examined whether DNA metabarcoding could be used to determine the diet of Cape Gannet and African Penguin breeding in Algoa Bay, South Africa. Then, this method was used to investigate the influence of intrinsic (both seabird species) and extrinsic (African Penguins) factors on the diet of the two seabird species. For the first data chapter, stomach content samples and faecal matter were collected concurrently from breeding Cape Gannets and African Penguins on Bird Island. DNA was successfully extracted from most faecal matter samples and the primers (18S_SSU, 16S_Fish) used for group, taxa and fish prey identification allowed amplification of prey DNA for both study species. A similar piscivorous diet was determined by both dietary methods for Cape Gannets with Sardine Sardinops sagax and Atlantic Saury Scomberesox saurus dominating the diet. Sardine also dominated the African Penguin diet in both dietary methods. In addition, DNA metabarcoding in African Penguins revealed a more diverse diet compared to the one determined by stomach content analysis. This was likely due to the limitations on the allowed number of stomach content samples to be collected for that Endangered species. Non-invasive DNA metabarcoding of faecal matter was then used to investigate whether the diet varied with breeding stages (incubation, chick-rearing) and age classes (chick-rearing adults, chicks) in both seabird species, but also breeding colonies (Algoa Bay: Bird Island, St Croix Island) in African Penguins. DNA metabarcoding revealed that breeding stages influenced the diet of Cape Gannets and African Penguins on Bird Island where prey species diversity was greater for incubating adults. On the contrary, the diet of incubating and chick-rearing penguins on St Croix Island was similar. When comparing the diet of African Penguins between Bird Island and St Croix Island, there was an increased overlap in diet composition between incubating and chick-rearing adults on St Croix Island when compared to Bird Island. Importantly, DNA metabarcoding indicated an increase in fishery interactions in Algoa Bay, particularly for Cape Gannets and the hake Merluccius spp. fishery, where the contribution of hake to chick-rearing adults and chick diet was considerably greater than incubating adult diet. In this study, I showed that DNA metabarcoding of faecal matter provides an opportunity for non-invasive dietary studies in two southern African endemic and Endangered seabird species. Incorporating non-invasive methods as a complement to other dietary methods for monitoring seabird trophic ecology is crucial when considering the worsening status of several seabird species. , Thesis (MSc) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Effects of annealing on the structural and optical properties of nanostructured TiO2
- Talla, Assane, Urgessa, Zelalem
- Authors: Talla, Assane , Urgessa, Zelalem
- Date: 2023-12
- Subjects: Titanium dioxide , Nanostructured materials , Nanotubes
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62655 , vital:72907
- Description: In this thesis, the structural, morphological and optical properties of titanium dioxide (TiO2) are investigated. Titanium dioxide (TiO2) nanotubes are prepared by anodic oxidation of titanium foil. The as-anodised samples are thermally annealed at various temperatures in nitrogen, air, oxygen and vacuum. The purpose is to study how the annealing conditions affect the properties of the nanostructures, including the anatase to rutile phase transformation. In all annealing atmospheres, except in vacuum, the dominant phase is found to be anatase when annealing is performed up to 600 oC. Above 700 oC the rutile phase becomes dominant. The anatase phase is stable above 600 oC in vacuum and does not evolve significantly up to 900 oC. The morphologies of the tubes tend to deteriorate with increased annealing temperature, in nitrogen, air and oxygen atmospheres, due to sintering effects. However, the integrity of the nanotubes is maintained up to 900 oC in vacuum. The photoluminescence (PL) spectra suggest mainly the presence of oxygen vacancies and self-trapped excitons, with respective emission bands around 2.5 eV and 2.3 eV. The results show that both the annealing temperature and atmosphere strongly influence the crystalline and optical properties of the TiO2 nanotubes. In addition, the phase transformation from anatase to rutile for samples annealed in an oxygen-rich environment is investigated in detail. Complementary structural information obtained from transmission electron microscopy and Raman analysis for oxygen-annealed samples reveals that the nucleation of the rutile phase starts from the titanium substrate and then propagates along the tubes. The results provide suitable annealing conditions to control the phase content and morphology of anodic TiO2 nanotubes. The PL characteristics of bulk crystalline anatase TiO2, namely virgin and hydrogen-annealed at 600 oC for 1 h, are studied. The low temperature PL spectra at 5.5 K shows near band edge (NBE) emissions with two dominant lines ascribed to shallow donor bound exciton and possibly free to bound recombination. The two main transitions are assisted by optical phononmodes. Temperature-dependent PL measurements performed on these anatase crystals reveal that the donor bound exciton is stable below 90 K. Hydrogen trapped in oxygen vacancies is proposed to be the shallow donor. In addition, two activation processes are involved for the thermal quenching of donor bound excitons. The total activation energy is found to correlate well with the localisation energy of the bound exciton. Site-selective PL spectra obtained from anodic TiO2 tubes reveals that the luminescence of the nanostructures depends on the morphology. The result shows unusual near-band edge emission (NBE) for these structures, which is rarely observed in indirect band gap TiO2. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Talla, Assane , Urgessa, Zelalem
- Date: 2023-12
- Subjects: Titanium dioxide , Nanostructured materials , Nanotubes
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62655 , vital:72907
- Description: In this thesis, the structural, morphological and optical properties of titanium dioxide (TiO2) are investigated. Titanium dioxide (TiO2) nanotubes are prepared by anodic oxidation of titanium foil. The as-anodised samples are thermally annealed at various temperatures in nitrogen, air, oxygen and vacuum. The purpose is to study how the annealing conditions affect the properties of the nanostructures, including the anatase to rutile phase transformation. In all annealing atmospheres, except in vacuum, the dominant phase is found to be anatase when annealing is performed up to 600 oC. Above 700 oC the rutile phase becomes dominant. The anatase phase is stable above 600 oC in vacuum and does not evolve significantly up to 900 oC. The morphologies of the tubes tend to deteriorate with increased annealing temperature, in nitrogen, air and oxygen atmospheres, due to sintering effects. However, the integrity of the nanotubes is maintained up to 900 oC in vacuum. The photoluminescence (PL) spectra suggest mainly the presence of oxygen vacancies and self-trapped excitons, with respective emission bands around 2.5 eV and 2.3 eV. The results show that both the annealing temperature and atmosphere strongly influence the crystalline and optical properties of the TiO2 nanotubes. In addition, the phase transformation from anatase to rutile for samples annealed in an oxygen-rich environment is investigated in detail. Complementary structural information obtained from transmission electron microscopy and Raman analysis for oxygen-annealed samples reveals that the nucleation of the rutile phase starts from the titanium substrate and then propagates along the tubes. The results provide suitable annealing conditions to control the phase content and morphology of anodic TiO2 nanotubes. The PL characteristics of bulk crystalline anatase TiO2, namely virgin and hydrogen-annealed at 600 oC for 1 h, are studied. The low temperature PL spectra at 5.5 K shows near band edge (NBE) emissions with two dominant lines ascribed to shallow donor bound exciton and possibly free to bound recombination. The two main transitions are assisted by optical phononmodes. Temperature-dependent PL measurements performed on these anatase crystals reveal that the donor bound exciton is stable below 90 K. Hydrogen trapped in oxygen vacancies is proposed to be the shallow donor. In addition, two activation processes are involved for the thermal quenching of donor bound excitons. The total activation energy is found to correlate well with the localisation energy of the bound exciton. Site-selective PL spectra obtained from anodic TiO2 tubes reveals that the luminescence of the nanostructures depends on the morphology. The result shows unusual near-band edge emission (NBE) for these structures, which is rarely observed in indirect band gap TiO2. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Effects of fire on architecture and composition of canopy shrubs in subtropical dune thicket of the southeastern Cape Floristic Region
- Strydom, Tiaan, Grobler, Adriaan
- Authors: Strydom, Tiaan , Grobler, Adriaan
- Date: 2023-12
- Subjects: Plant ecology -- Research , Plant communities -- South Africa , Browsing (Animal behavior)
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62632 , vital:72899
- Description: Disturbance, such as fire and megaherbivory, is a pervasive phenomenon globally and has different effects on the flora and vegetation of different ecosystems. The Cape Floristic Region (CFR) of South Africa includes the distinctive Subtropical Thicket biome, which occurs as interrupted blocks that are not exposed to fire, but also as mosaics with the fire-prone vegetation of the Fynbos biome, especially on coastal dunes where thicket species are exposed to fire. Subtropical Dune Thicket (hereafter thicket) thus co-occurs with Fynbos, capable of supporting intense fires that can lead to thicket shrub defoliation and mortality. Thicket also experiences disturbance from meso- and megaherbivores that causes defoliation and mortality of shrubs. The aim of this study was to investigate the resilience of thicket shrub species to varying disturbance levels from fire and browsing to understand what drives thicket persistence in a fire-prone landscape. Firstly, I established the architectural traits of thicket species in long unburnt and post-fire contexts and investigated the relationships between these traits and the survival, resprouting ability and persistence of thicket shrubs. In mature thicket, I identified three distinct architectural guilds, namely hedge formers, lateral spreaders, and vertical growers. In post-fire thicket I identified three resprouting architectures, namely weak resprouters, moderate resprouters and strong resprouters. There was no strong relationship between the unburnt and post-fire resprouting architectures. Secondly, I compared thicket species and architectural composition in patches of landscape that experience different levels of fire exposure to assess the potential effect of fire frequency on determining thicket structure. I recognised three thicket vegetation units, each with a distinct structure and each corresponding to the level of fire exposure in the landscape. The first unit, forest-thicket, is exposed to low levels of fire frequency (> 100 years) and harbours forest species, many of which were vertical growers. The second unit, thicket, is exposed to moderate levels of fire frequency (50-100 years) and is dominated by lateral spreaders. The last unit, fynbos-thicket, is exposed to high levels of fire frequency (10-50 years) and here hedge-forming shrubs dominate the canopy cover. Forest-thicket and fynbos-thicket had a diverse set of shrub species with many being restricted to their respective vegetation type, whereas thicket had a lower diversity with no unique shrub species. , Thesis (DPhil) -- Faculty of Science, School of Natural Resource Management, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Strydom, Tiaan , Grobler, Adriaan
- Date: 2023-12
- Subjects: Plant ecology -- Research , Plant communities -- South Africa , Browsing (Animal behavior)
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62632 , vital:72899
- Description: Disturbance, such as fire and megaherbivory, is a pervasive phenomenon globally and has different effects on the flora and vegetation of different ecosystems. The Cape Floristic Region (CFR) of South Africa includes the distinctive Subtropical Thicket biome, which occurs as interrupted blocks that are not exposed to fire, but also as mosaics with the fire-prone vegetation of the Fynbos biome, especially on coastal dunes where thicket species are exposed to fire. Subtropical Dune Thicket (hereafter thicket) thus co-occurs with Fynbos, capable of supporting intense fires that can lead to thicket shrub defoliation and mortality. Thicket also experiences disturbance from meso- and megaherbivores that causes defoliation and mortality of shrubs. The aim of this study was to investigate the resilience of thicket shrub species to varying disturbance levels from fire and browsing to understand what drives thicket persistence in a fire-prone landscape. Firstly, I established the architectural traits of thicket species in long unburnt and post-fire contexts and investigated the relationships between these traits and the survival, resprouting ability and persistence of thicket shrubs. In mature thicket, I identified three distinct architectural guilds, namely hedge formers, lateral spreaders, and vertical growers. In post-fire thicket I identified three resprouting architectures, namely weak resprouters, moderate resprouters and strong resprouters. There was no strong relationship between the unburnt and post-fire resprouting architectures. Secondly, I compared thicket species and architectural composition in patches of landscape that experience different levels of fire exposure to assess the potential effect of fire frequency on determining thicket structure. I recognised three thicket vegetation units, each with a distinct structure and each corresponding to the level of fire exposure in the landscape. The first unit, forest-thicket, is exposed to low levels of fire frequency (> 100 years) and harbours forest species, many of which were vertical growers. The second unit, thicket, is exposed to moderate levels of fire frequency (50-100 years) and is dominated by lateral spreaders. The last unit, fynbos-thicket, is exposed to high levels of fire frequency (10-50 years) and here hedge-forming shrubs dominate the canopy cover. Forest-thicket and fynbos-thicket had a diverse set of shrub species with many being restricted to their respective vegetation type, whereas thicket had a lower diversity with no unique shrub species. , Thesis (DPhil) -- Faculty of Science, School of Natural Resource Management, 2023
- Full Text:
- Date Issued: 2023-12
Effects of selected natural flavonoids on an optimized insulin resistance induction model on myotubes and hepatocytes in vitro
- Authors: Van de Venter, Ruben
- Date: 2023-12
- Subjects: Flavonoid , Insulin resistance , Myotubes and hepatocytes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63049 , vital:73085
- Description: Introduction: As the third largest life-threatening non-communicable disease, further research to improve T2DM treatment remains pivotal. The approved insulin sensitizing agents, metformin and thiazolidinediones, although effective, have an array of adverse effects. This leads to the growing need for safer insulin sensitizing agents. Aims: To induce insulin resistance, an insulin resistance induction (IRI) model consisting of palmitic acid (PA), fructose, and dexamethasone (DEX), was optimized. The model was utilized to compare the insulin sensitizing efficacy of chrysin, apigenin, luteolin, and quercetin. The most effective flavonoid was extrapolated based on the hydroxylation hypothesis and relevant SAR. The flavonoid was combined with metformin to evaluate potential insulin sensitizing synergism. Methods: C3A hepatocytes and L6 myotubes were exposed to the IRI models: IR1, IR2, and OIR, for 24 and 48h. Morphological features indicative of insulin resistance were monitored through high-content analysis (HCA). Thereafter, cells were exposed to OIR and concurrently treated with the selected flavonoids. Cytotoxicity, oxidative stress (OS), mitochondrial content, mitochondrial membrane potential (MMP), and lipid accumulation, were once again evaluated through HCA. Subsequently, quercetin was combined with metformin (QM); insulin resistant conditions established through OIR exposure, and QM administered as prophylaxis. The efficacy of QM was determined through changes in phosphorylated-Akt, glucose uptake, and gluconeogenesis. Results: IR1 and IR2 demonstrated excessive potency, whereas OIR consistently generated insulin resistant C3A/L6 cells by increasing OS (↑14%/20%), lipid accumulation (0.7-fold/1.5-fold), and decreasing MMP (↓4%/6%). Of the selected flavonoids, quercetin was most effective at ameliorating each of these parameters. Furthermore, QM demonstrated potential insulin sensitizing synergism, as it improved Akt phosphorylation (Thr308: ↑31%/↑17%; Ser473: ↑29%), glucose uptake (↑10%/ 5%), and suppressed hepatic gluconeogenesis (15↓%) more effectively compared to monotherapy. Conclusions: OIR is an effective model for the induction of complete early-stage insulin resistance in myotubes and hepatocytes. Quercetin demonstrates exceptional antidiabetic activity due its unique expression of hydroxyl groups. Lastly, QM, comparative to monotherapy, improves insulin sensitivity with enhanced efficacy. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Van de Venter, Ruben
- Date: 2023-12
- Subjects: Flavonoid , Insulin resistance , Myotubes and hepatocytes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/63049 , vital:73085
- Description: Introduction: As the third largest life-threatening non-communicable disease, further research to improve T2DM treatment remains pivotal. The approved insulin sensitizing agents, metformin and thiazolidinediones, although effective, have an array of adverse effects. This leads to the growing need for safer insulin sensitizing agents. Aims: To induce insulin resistance, an insulin resistance induction (IRI) model consisting of palmitic acid (PA), fructose, and dexamethasone (DEX), was optimized. The model was utilized to compare the insulin sensitizing efficacy of chrysin, apigenin, luteolin, and quercetin. The most effective flavonoid was extrapolated based on the hydroxylation hypothesis and relevant SAR. The flavonoid was combined with metformin to evaluate potential insulin sensitizing synergism. Methods: C3A hepatocytes and L6 myotubes were exposed to the IRI models: IR1, IR2, and OIR, for 24 and 48h. Morphological features indicative of insulin resistance were monitored through high-content analysis (HCA). Thereafter, cells were exposed to OIR and concurrently treated with the selected flavonoids. Cytotoxicity, oxidative stress (OS), mitochondrial content, mitochondrial membrane potential (MMP), and lipid accumulation, were once again evaluated through HCA. Subsequently, quercetin was combined with metformin (QM); insulin resistant conditions established through OIR exposure, and QM administered as prophylaxis. The efficacy of QM was determined through changes in phosphorylated-Akt, glucose uptake, and gluconeogenesis. Results: IR1 and IR2 demonstrated excessive potency, whereas OIR consistently generated insulin resistant C3A/L6 cells by increasing OS (↑14%/20%), lipid accumulation (0.7-fold/1.5-fold), and decreasing MMP (↓4%/6%). Of the selected flavonoids, quercetin was most effective at ameliorating each of these parameters. Furthermore, QM demonstrated potential insulin sensitizing synergism, as it improved Akt phosphorylation (Thr308: ↑31%/↑17%; Ser473: ↑29%), glucose uptake (↑10%/ 5%), and suppressed hepatic gluconeogenesis (15↓%) more effectively compared to monotherapy. Conclusions: OIR is an effective model for the induction of complete early-stage insulin resistance in myotubes and hepatocytes. Quercetin demonstrates exceptional antidiabetic activity due its unique expression of hydroxyl groups. Lastly, QM, comparative to monotherapy, improves insulin sensitivity with enhanced efficacy. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
Establishment of a high-content neurodegenerative disease model screening platform
- Authors: Swanepoel, Bresler
- Date: 2023-12
- Subjects: Molecular neurobiology , Nervous system -- Diseases , Nervous system -- Degeneration
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62644 , vital:72906
- Description: The identification of viable therapeutic targets and new treatments for central nervous system disorders, especially neurodegenerative diseases, remain major challenges in the field of drug discovery. Over the past few years there has been a steady decline in the turnaround time of current screening processes to yield viable drugs. Therefore, an increasing need exists for better technologies, protocols, and the screening of larger libraries. High-throughput screening provides the best solution to this problem and has become a key part in the drug discovery and development process. Likewise, high-content analysis has gained popularity over the past few years and is suitable for high-throughput screening. The aim of this study was to establish a comprehensive in vitro neuroprotective screening platform incorporating high throughput screening, using Parkinson’s disease as the neurodegenerative disease of interest. To evaluate the success of this platform, the neuroprotective potential of two mushrooms (Hericium erinaceus and Phlebopus sudanicus), two plants (Lippia javanica and Myrothamnus flabellifolia) and two seaweeds (Eucheuma denticulatum and Kappaphycus alvarezii) were investigated. Aqueous and ethanolic extracts of the selected natural products were evaluated across 21 parameters associated with four hallmarks of neurodegeneration: acquiring senescence, acquiring cell death, neuroinflammation and altered metabolism/cell survival. Based on the effects of these selected natural products on the 21 parameters, their potential mechanisms of action were elucidated. In addition to this, the natural products were scored under each of these therapeutic targets in an attempt to identify the most suitable animal models for future studies. The scoring system indicated that animal models investigating anti-senescence ability would be more suited for extracts of H. erinaceus, P. sudanicus and E. denticulatum whereas studies investigating the prevention of cell death would be more suited for extracts of E. denticulatum, L. javanica and K. alvarezii. Likewise, models based on neuroinflammation would be best suited for extracts of H. erinaceus, E. denticulatum and L. javanica while studies examining altered metabolism/cell survival would be best suited to extracts of H. erinaceus, E. denticulatum, K. alvarezii and M. flabellifolia. Considering the pleiotropic nature of the selected natural products, models that can combine these therapeutic targets could be of great interest. 6-OHDA proved to be capable of inducing favourable effects, in all the parameters investigated, with regard to a neurodegenerative state. However, it is known to have some disadvantages when it comes to pathological features such as the lack of the ability to induce Lewy body formation. Choosing the correct inducer remains a daunting task and no model, whether cell-based or animal-based, exists yet in which all the features of neurodegenerative diseases have been successfully replicated. The limitations of the current models, however, does not mean that they do not produce valuable insights. This is especially true if the mechanism of action for a specific compound or natural product is unknown. Animal models are still indispensable for the validation and interpretation of the results obtained from cell models with particular importance to toxicity. Therefore, this study assessed the best studied extract with the highest overall score for its toxicity using a zebrafish larvae-based model. Assessment of the toxicity of H. erinaceus revealed that both aqueous and ethanolic extracts resulted in death at the highest concentrations. This was supported by the results obtained in the in vitro cytotoxicity screening. In conclusion, this highlighted the importance of using physiologically relevant concentrations and supported the translational value of the current cell-based screening model to animal models and possibly humans. The findings of the present study suggest that a scoring system, which categorizes the different activities of selected natural products into distinct groups, can be a useful tool to improve the translatability of in vitro results to animal models. Furthermore, the current study arguably provides the most comprehensive neuroprotective screening platform in existence. Future research can look at expanding the platform through incorporation of additional parameters based on other hallmarks of neurodegeneration, not covered in this study, including protein folding and aggregation, altered epigenetics and the examination of other neuronal markers such as the involvement of astrocytes, oligodendrocytes, and microglia. In addition to this, future research can make use of more sophisticated cell models such as differentiated, human induced pluripotent stem cells and three-dimensional cultures. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Swanepoel, Bresler
- Date: 2023-12
- Subjects: Molecular neurobiology , Nervous system -- Diseases , Nervous system -- Degeneration
- Language: English
- Type: Doctorial theses , text
- Identifier: http://hdl.handle.net/10948/62644 , vital:72906
- Description: The identification of viable therapeutic targets and new treatments for central nervous system disorders, especially neurodegenerative diseases, remain major challenges in the field of drug discovery. Over the past few years there has been a steady decline in the turnaround time of current screening processes to yield viable drugs. Therefore, an increasing need exists for better technologies, protocols, and the screening of larger libraries. High-throughput screening provides the best solution to this problem and has become a key part in the drug discovery and development process. Likewise, high-content analysis has gained popularity over the past few years and is suitable for high-throughput screening. The aim of this study was to establish a comprehensive in vitro neuroprotective screening platform incorporating high throughput screening, using Parkinson’s disease as the neurodegenerative disease of interest. To evaluate the success of this platform, the neuroprotective potential of two mushrooms (Hericium erinaceus and Phlebopus sudanicus), two plants (Lippia javanica and Myrothamnus flabellifolia) and two seaweeds (Eucheuma denticulatum and Kappaphycus alvarezii) were investigated. Aqueous and ethanolic extracts of the selected natural products were evaluated across 21 parameters associated with four hallmarks of neurodegeneration: acquiring senescence, acquiring cell death, neuroinflammation and altered metabolism/cell survival. Based on the effects of these selected natural products on the 21 parameters, their potential mechanisms of action were elucidated. In addition to this, the natural products were scored under each of these therapeutic targets in an attempt to identify the most suitable animal models for future studies. The scoring system indicated that animal models investigating anti-senescence ability would be more suited for extracts of H. erinaceus, P. sudanicus and E. denticulatum whereas studies investigating the prevention of cell death would be more suited for extracts of E. denticulatum, L. javanica and K. alvarezii. Likewise, models based on neuroinflammation would be best suited for extracts of H. erinaceus, E. denticulatum and L. javanica while studies examining altered metabolism/cell survival would be best suited to extracts of H. erinaceus, E. denticulatum, K. alvarezii and M. flabellifolia. Considering the pleiotropic nature of the selected natural products, models that can combine these therapeutic targets could be of great interest. 6-OHDA proved to be capable of inducing favourable effects, in all the parameters investigated, with regard to a neurodegenerative state. However, it is known to have some disadvantages when it comes to pathological features such as the lack of the ability to induce Lewy body formation. Choosing the correct inducer remains a daunting task and no model, whether cell-based or animal-based, exists yet in which all the features of neurodegenerative diseases have been successfully replicated. The limitations of the current models, however, does not mean that they do not produce valuable insights. This is especially true if the mechanism of action for a specific compound or natural product is unknown. Animal models are still indispensable for the validation and interpretation of the results obtained from cell models with particular importance to toxicity. Therefore, this study assessed the best studied extract with the highest overall score for its toxicity using a zebrafish larvae-based model. Assessment of the toxicity of H. erinaceus revealed that both aqueous and ethanolic extracts resulted in death at the highest concentrations. This was supported by the results obtained in the in vitro cytotoxicity screening. In conclusion, this highlighted the importance of using physiologically relevant concentrations and supported the translational value of the current cell-based screening model to animal models and possibly humans. The findings of the present study suggest that a scoring system, which categorizes the different activities of selected natural products into distinct groups, can be a useful tool to improve the translatability of in vitro results to animal models. Furthermore, the current study arguably provides the most comprehensive neuroprotective screening platform in existence. Future research can look at expanding the platform through incorporation of additional parameters based on other hallmarks of neurodegeneration, not covered in this study, including protein folding and aggregation, altered epigenetics and the examination of other neuronal markers such as the involvement of astrocytes, oligodendrocytes, and microglia. In addition to this, future research can make use of more sophisticated cell models such as differentiated, human induced pluripotent stem cells and three-dimensional cultures. , Thesis (PhD) -- Faculty of Science, School of Biomolecular and Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Evaluating antidiabetic properties of selected African medicinal plants in a cell-based model
- Sirkhotte, Saeedah, Reddy, Shanika
- Authors: Sirkhotte, Saeedah , Reddy, Shanika
- Date: 2023-12
- Subjects: Medicinal plants -- South Africa , Insulin resistance , Gluconeogenesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62600 , vital:72827
- Description: The World Health Organisation lists diabetes as one of the major non-communicable diseases affecting the world, and its prevalence is expected to increase rapidly. Type II diabetes mellitus (T2DM) is characterised by insulin resistance and impaired blood glucose control. T2DM is of growing concern within South Africa, with 10.8% of the population currently diagnosed. The popularity, as well as availability, of traditional plant-based medicine in South Africa, might provide a solution. Antidiabetic potential is commonly tested by in vitro assays, however the methods to test this potential via gluconeogenesis are limited. This project aimed to optimise an in vitro hepatic gluconeogenesis model. In addition, this project aimed to determine the antidiabetic properties of Prunus africana, Hypoxis stellipilis, and Eriocephalus africanus by in vitro analysis. These properties were examined in human hepatoma cells (C3A cell line) and rat pancreatic cells (INS1 cell line) and methods included: cytotoxicity analysis, Amplex® red glucose oxidase assay, antibody staining, gene expression analysis by RT-qPCR, oxidative stress analysis, and calcium signaling for insulin release. Insulin resistance was successfully induced by exposing C3A hepatocarcinoma cells to a combination treatment of 50 μM dexamethasone, 1.25 mM fructose and 0.125 mM palmitic acid for a period of three days. Thereafter, gluconeogenesis was assessed using the Amplex® red glucose oxidase assay. The established model was effective in inducing insulin resistance and upregulating gluconeogenesis. Of the tested plant extracts, H. stellipilis showed the most potential as an antidiabetic treatment. It had low toxicity, significantly decreased hepatic glucose production and reduced the amount of phosphoenolpyruvate carboxykinase (PCK) and well as PCK gene expression, and reduced lipid content and reactive oxygen species (ROS) in the C3A cell line. H. stellipilis increased calcium signalling in INS1 rat insulinoma cells, however there was a decrease in expression of genes for insulin and glucose transporter 2 after 6 hr exposure. H. stellipilis appears be beneficial as an antidiabetic treatment. Although antidiabetic studies have been done on other Hypoxis species, this is the first study on the effects of H. stellipilis on gluconeogenesis and diabetes. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Sirkhotte, Saeedah , Reddy, Shanika
- Date: 2023-12
- Subjects: Medicinal plants -- South Africa , Insulin resistance , Gluconeogenesis
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62600 , vital:72827
- Description: The World Health Organisation lists diabetes as one of the major non-communicable diseases affecting the world, and its prevalence is expected to increase rapidly. Type II diabetes mellitus (T2DM) is characterised by insulin resistance and impaired blood glucose control. T2DM is of growing concern within South Africa, with 10.8% of the population currently diagnosed. The popularity, as well as availability, of traditional plant-based medicine in South Africa, might provide a solution. Antidiabetic potential is commonly tested by in vitro assays, however the methods to test this potential via gluconeogenesis are limited. This project aimed to optimise an in vitro hepatic gluconeogenesis model. In addition, this project aimed to determine the antidiabetic properties of Prunus africana, Hypoxis stellipilis, and Eriocephalus africanus by in vitro analysis. These properties were examined in human hepatoma cells (C3A cell line) and rat pancreatic cells (INS1 cell line) and methods included: cytotoxicity analysis, Amplex® red glucose oxidase assay, antibody staining, gene expression analysis by RT-qPCR, oxidative stress analysis, and calcium signaling for insulin release. Insulin resistance was successfully induced by exposing C3A hepatocarcinoma cells to a combination treatment of 50 μM dexamethasone, 1.25 mM fructose and 0.125 mM palmitic acid for a period of three days. Thereafter, gluconeogenesis was assessed using the Amplex® red glucose oxidase assay. The established model was effective in inducing insulin resistance and upregulating gluconeogenesis. Of the tested plant extracts, H. stellipilis showed the most potential as an antidiabetic treatment. It had low toxicity, significantly decreased hepatic glucose production and reduced the amount of phosphoenolpyruvate carboxykinase (PCK) and well as PCK gene expression, and reduced lipid content and reactive oxygen species (ROS) in the C3A cell line. H. stellipilis increased calcium signalling in INS1 rat insulinoma cells, however there was a decrease in expression of genes for insulin and glucose transporter 2 after 6 hr exposure. H. stellipilis appears be beneficial as an antidiabetic treatment. Although antidiabetic studies have been done on other Hypoxis species, this is the first study on the effects of H. stellipilis on gluconeogenesis and diabetes. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Evaluation of the antidiabetic potential, safety and efficacy of selected natural products using zebrafish larvae and in vitro bioassays
- Reddy, Shanika, Dambuza, Ntokozo
- Authors: Reddy, Shanika , Dambuza, Ntokozo
- Date: 2023-12
- Subjects: Traditional medicine -- Research -- South Africa , Medicinal plants -- South Africa -- Research , Insulin resistance
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62575 , vital:72825
- Description: Abstract. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Reddy, Shanika , Dambuza, Ntokozo
- Date: 2023-12
- Subjects: Traditional medicine -- Research -- South Africa , Medicinal plants -- South Africa -- Research , Insulin resistance
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62575 , vital:72825
- Description: Abstract. , Thesis (MSc) -- Faculty of Science, School of Biomolecular & Chemical Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Evidence of Late Holocene extreme marine wave event (tsunami) deposits along the South African coast and implications for coastal zone management
- Authors: Mfikili, Athi Nkosibonile
- Date: 2023-12
- Subjects: Tsunamis -- South Africa , Coasts -- Risk assessment , Sediments (Geology)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62517 , vital:72811
- Description: Although extreme marine wave events such as tsunamis and storm surges have always been part of human existence, their impact on ever-growing coastal population of the world’s coast was highlighted by the recent catastrophic events over the past three decades. Although in situ observations and eyewitness accounts have improved our ability to record and interpret wave inundation by modern extreme marine events, records documenting inundation by pre-historic and historical events are relatively sparse to provide reasonable information on their distribution, magnitude and frequency intervals in most parts of the world. Owing to consequences these natural coastal hazards have on coastal population and infrastructure of the world’s coast, onshore sedimentary deposits preserved in the geological records have been extensively utilized by scientists worldwide to reconstruct the record of pre-historic and historical events and establish the recurrence interval of future events. Although studies investigating inundation of past tsunami has increased worldwide over the past two decades, research on extreme marine inundation has received little attention along the South African coast, despite known inundation by recent events and potential source mechanisms. Therefore, the aim of this study is to investigate sedimentary evidence of past tsunamis and related extreme marine wave events (i.e., storm surges) preserved in the recent geological archive of several coastal environments along the South African coast. The Swartkops, Kabeljous, Kromme and Keurbooms estuaries located in log-spiral bays along the south-east coast and sheltered coastal systems of the Berg Estuary and Verlorenvlei as well as coastal lowlands of the Dwarskersbos on the west coast were selected as the study sites. The sediment cores were collected from these coastal environments and identification of extreme marine wave inundation was based on the recognition of distinct anomalous sand layers. To characterise sediment transport and reconstruct provenance source origin of the deposits, a combination of sedimentological (i.e., grain size distribution), exoscopy (i.e., quartz grain surface microtextures) and micropaleontological (i.e., foraminiferal assemblages) proxies were utilized. Furthermore, age estimation of the deposits was determined using a combination of radiocarbon (14C) and radiometric (137Cs and 210Pb) dating methods.Evidence of coastal flooding by high-energy marine wave events is found preserved in the stratigraphic records of Swartkops and Kabeljous estuaries along the south-east coast and lowlands of Dwarskersbos on the west coast in the form of anomalous sand deposits (layers). The anomalous deposits of Swartkops and Kabeljous estuaries generally consist of gravel-sized shell fragments often with a sharp erosive contact suggesting deposition by a highly energetic marine wave event. Although the preservation varies between cores, a maximum of three anomalous sand depositional layers are preserved in the Swartkops whereas only a single layer in the Kabeljous Estuary with a basal layer of calcrete deposits. 210Pb and 14C dating, constrain the ages of the younger deposits (i.e., the uppermost layer) at Swartkops between 1770-1804 AD and 339-3 cal. BP (1611-1947 cal. AD), respectively. Although these ages span over a wide period, they are interpreted to represent evidence of one of the historical tsunamis generated in the subduction zones of the Indian Ocean e.g., 1762 AD and 1797 AD events generated by 8.8 and 8.0 Mw earthquakes in the Arakan and Sunda Subduction Zones, respectively. Furthermore, the deposits could also represent geological evidence of the 1833 Mentawai events whereas evidence of 1883 Krakatau tsunami is not disregarded, since this event reportedly inundated Algoa Bay. On the other hand, the 14C dating constrain the ages of the second anomalous deposits between 1526-1253 cal. BP (424-697 cal. AD), whereas the older anomalous deposits preserved in the deeper sections of the Swartkops cores as well as the backwater channel of the Kabeljous Estuary are constrained to have been deposited around 4000 cal. BP. Although there is no known locally documented extreme marine wave event during this period, these deposits are interpreted to represent late and mid-Holocene tsunamis associated with mega-thrust subduction zones of the Indian Ocean whereas local submarine landslide generated event are also not disregarded entirely. On the west coast, three anomalous deposits representing extreme marine wave inundation are preserved in the coastal lowlands of the Dwarskersbos. Although the general sedimentary features and thickness vary between the deposits, the first anomalous deposits in the uppermost section of the cores consist of medium sand with scattered shell fragments whereas, the third anomalous deposits in the deeper section of the cores are generally coarser with gravel-sized shell fragments and sharp erosive basal contacts. By contrast, the second anomalous deposits consist of three successive sub-layers of yellow sand with variable sedimentary features and these layers represent successive wave inundation events. Although the sedimentary characteristics of these sub-layers varies, it was noted that the lowermost layers consist of coarser and less well sorted sediments often with basal erosive contact, suggesting that the first wave was more energetic than the two-succeeding waves. Furthermore, calibrated 14C dated shell fragments from the first and second anomalous deposits yielded ‘post-bomb’ ages suggesting deposition after 1950 AD. Given their position within the stratigraphic records, the two deposits are interpreted to represent first geological evidence of the 2008 west coast and 1969 Dwarskersbos events, respectively. On the other hand, the 14C dated shell fragments constrain the deposition of the third anomalous deposits between 315-0 cal. BP (1635-11950 cal. AD) and 358-0 cal. BP (1592-1950 cal. AD), respectively. The third anomalous deposits are interpreted to the 07 April 1620 event, which was described as ‘Two startling thunderclaps’ near Robben Island. Although initially associated to earthquakes, there are no records of an earthquake during this period, therefore, we postulate that the 1620 event could have been a similar event to that of 2008 that inundated the west coast region and/or an unknown event. While it is acknowledged that the absence of reliable source mechanisms poses a great challenge in the reconstruction of extreme marine wave events inundation along the south-east coast, the findings of exoscopy and micropaleontological analyses suggest that the deposits were transported to their depositional environments, although resultant microtextural features and occurrence of individual foraminiferal species and their taphonomical conditions is dependent on coastal setting. The south-east coast deposits consist of highly diverse foraminiferal assemblages, which are dominated by marine and marginal-marine taxa with relatively low abundances of estuarine-brackish species and variable taphonomical conditions. Furthermore, the mechanical-induced features such as percussion marks, fresh surfaces with sharp edges were still preserved on quartz grain surface of the Swartkops deposits, despite dominance by chemical-induced features such as dissolution. By contrast, grain surface microtextural signatures of the Dwarskersbos deposits are dominated by mechanical features such as fresh surfaces and v-percussion marks. Furthermore, the foraminiferal assemblages of the Dwarskersbos deposits consist of exclusively marine and marginal-marine species, suggesting that the sediments were sourced from shallow water environments as well as the adjacent beach. It was further noted that the foraminiferal tests of these deposits consist of higher abundance of corroded and fragmented tests indicating deposition by high-energy conditions. , Thesis (D.Phil) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Mfikili, Athi Nkosibonile
- Date: 2023-12
- Subjects: Tsunamis -- South Africa , Coasts -- Risk assessment , Sediments (Geology)
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10948/62517 , vital:72811
- Description: Although extreme marine wave events such as tsunamis and storm surges have always been part of human existence, their impact on ever-growing coastal population of the world’s coast was highlighted by the recent catastrophic events over the past three decades. Although in situ observations and eyewitness accounts have improved our ability to record and interpret wave inundation by modern extreme marine events, records documenting inundation by pre-historic and historical events are relatively sparse to provide reasonable information on their distribution, magnitude and frequency intervals in most parts of the world. Owing to consequences these natural coastal hazards have on coastal population and infrastructure of the world’s coast, onshore sedimentary deposits preserved in the geological records have been extensively utilized by scientists worldwide to reconstruct the record of pre-historic and historical events and establish the recurrence interval of future events. Although studies investigating inundation of past tsunami has increased worldwide over the past two decades, research on extreme marine inundation has received little attention along the South African coast, despite known inundation by recent events and potential source mechanisms. Therefore, the aim of this study is to investigate sedimentary evidence of past tsunamis and related extreme marine wave events (i.e., storm surges) preserved in the recent geological archive of several coastal environments along the South African coast. The Swartkops, Kabeljous, Kromme and Keurbooms estuaries located in log-spiral bays along the south-east coast and sheltered coastal systems of the Berg Estuary and Verlorenvlei as well as coastal lowlands of the Dwarskersbos on the west coast were selected as the study sites. The sediment cores were collected from these coastal environments and identification of extreme marine wave inundation was based on the recognition of distinct anomalous sand layers. To characterise sediment transport and reconstruct provenance source origin of the deposits, a combination of sedimentological (i.e., grain size distribution), exoscopy (i.e., quartz grain surface microtextures) and micropaleontological (i.e., foraminiferal assemblages) proxies were utilized. Furthermore, age estimation of the deposits was determined using a combination of radiocarbon (14C) and radiometric (137Cs and 210Pb) dating methods.Evidence of coastal flooding by high-energy marine wave events is found preserved in the stratigraphic records of Swartkops and Kabeljous estuaries along the south-east coast and lowlands of Dwarskersbos on the west coast in the form of anomalous sand deposits (layers). The anomalous deposits of Swartkops and Kabeljous estuaries generally consist of gravel-sized shell fragments often with a sharp erosive contact suggesting deposition by a highly energetic marine wave event. Although the preservation varies between cores, a maximum of three anomalous sand depositional layers are preserved in the Swartkops whereas only a single layer in the Kabeljous Estuary with a basal layer of calcrete deposits. 210Pb and 14C dating, constrain the ages of the younger deposits (i.e., the uppermost layer) at Swartkops between 1770-1804 AD and 339-3 cal. BP (1611-1947 cal. AD), respectively. Although these ages span over a wide period, they are interpreted to represent evidence of one of the historical tsunamis generated in the subduction zones of the Indian Ocean e.g., 1762 AD and 1797 AD events generated by 8.8 and 8.0 Mw earthquakes in the Arakan and Sunda Subduction Zones, respectively. Furthermore, the deposits could also represent geological evidence of the 1833 Mentawai events whereas evidence of 1883 Krakatau tsunami is not disregarded, since this event reportedly inundated Algoa Bay. On the other hand, the 14C dating constrain the ages of the second anomalous deposits between 1526-1253 cal. BP (424-697 cal. AD), whereas the older anomalous deposits preserved in the deeper sections of the Swartkops cores as well as the backwater channel of the Kabeljous Estuary are constrained to have been deposited around 4000 cal. BP. Although there is no known locally documented extreme marine wave event during this period, these deposits are interpreted to represent late and mid-Holocene tsunamis associated with mega-thrust subduction zones of the Indian Ocean whereas local submarine landslide generated event are also not disregarded entirely. On the west coast, three anomalous deposits representing extreme marine wave inundation are preserved in the coastal lowlands of the Dwarskersbos. Although the general sedimentary features and thickness vary between the deposits, the first anomalous deposits in the uppermost section of the cores consist of medium sand with scattered shell fragments whereas, the third anomalous deposits in the deeper section of the cores are generally coarser with gravel-sized shell fragments and sharp erosive basal contacts. By contrast, the second anomalous deposits consist of three successive sub-layers of yellow sand with variable sedimentary features and these layers represent successive wave inundation events. Although the sedimentary characteristics of these sub-layers varies, it was noted that the lowermost layers consist of coarser and less well sorted sediments often with basal erosive contact, suggesting that the first wave was more energetic than the two-succeeding waves. Furthermore, calibrated 14C dated shell fragments from the first and second anomalous deposits yielded ‘post-bomb’ ages suggesting deposition after 1950 AD. Given their position within the stratigraphic records, the two deposits are interpreted to represent first geological evidence of the 2008 west coast and 1969 Dwarskersbos events, respectively. On the other hand, the 14C dated shell fragments constrain the deposition of the third anomalous deposits between 315-0 cal. BP (1635-11950 cal. AD) and 358-0 cal. BP (1592-1950 cal. AD), respectively. The third anomalous deposits are interpreted to the 07 April 1620 event, which was described as ‘Two startling thunderclaps’ near Robben Island. Although initially associated to earthquakes, there are no records of an earthquake during this period, therefore, we postulate that the 1620 event could have been a similar event to that of 2008 that inundated the west coast region and/or an unknown event. While it is acknowledged that the absence of reliable source mechanisms poses a great challenge in the reconstruction of extreme marine wave events inundation along the south-east coast, the findings of exoscopy and micropaleontological analyses suggest that the deposits were transported to their depositional environments, although resultant microtextural features and occurrence of individual foraminiferal species and their taphonomical conditions is dependent on coastal setting. The south-east coast deposits consist of highly diverse foraminiferal assemblages, which are dominated by marine and marginal-marine taxa with relatively low abundances of estuarine-brackish species and variable taphonomical conditions. Furthermore, the mechanical-induced features such as percussion marks, fresh surfaces with sharp edges were still preserved on quartz grain surface of the Swartkops deposits, despite dominance by chemical-induced features such as dissolution. By contrast, grain surface microtextural signatures of the Dwarskersbos deposits are dominated by mechanical features such as fresh surfaces and v-percussion marks. Furthermore, the foraminiferal assemblages of the Dwarskersbos deposits consist of exclusively marine and marginal-marine species, suggesting that the sediments were sourced from shallow water environments as well as the adjacent beach. It was further noted that the foraminiferal tests of these deposits consist of higher abundance of corroded and fragmented tests indicating deposition by high-energy conditions. , Thesis (D.Phil) -- Faculty of Science, School of Environmental Sciences, 2023
- Full Text:
- Date Issued: 2023-12
Experiences of mothers who are on tuberculosis treatment While caring for their children in Nelson Mandela Bay health district
- Authors: Mwadiwa, Chiedza
- Date: 2023-12
- Subjects: Caring experiences -- Nelson Mandela Bay , Tuberculosis treatment
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62935 , vital:73071
- Description: Women and mothers have an important role to play as caregivers of their children. However, mothers are often faced with challenges with fulfilling this important role. Many women value the caring role as a mother over other areas of their lives, and for ill women, such as those with tuberculosis (TB) and those on TB treatment, it can be difficult to relinquish maternal responsibility. Indeed, many mothers in South Africa and other low- and middle-income countries develop TB during pregnancy and postpartum because their immune systems are compromised. For a mother who is chronically ill, carrying out a mother’s caregiving role presents a range of challenges. However, few studies have addressed this problem or explored the experiences of such mothers. The purpose of the study was to understand the experiences of mothers who are on TB treatment while caring for their children in order to establish their support needs and thereby develop recommendations to assist CHWs, nurses and nurse managers at primary healthcare (PHC) clinics to provide optimum care to such women. The Socio-Ecological model was used as the theoretical lens to explore the phenomenon under investigation. A qualitative, exploratory-descriptive research design was identified as most suited to respond to the research question. Purposive sampling was used to select both the participants and the clinics in the Nelson Mandela Bay Health District (NMBHD) for the purpose of this study. The population was mothers on TB treatment caring for their children (aged five years or younger) who were attending either one of the two of the largest PHC clinics in Sub-district C in the NMBH. Altogether ten mothers on TB treatment caring for their children took part in individual semi-structured interviews conducted telephonically. Ethical clearance was obtained from Nelson Mandela University and permission was obtained from the Department of Health (DoH), district office, operational managers at the respective clinics, and the participants involved in the study. Trustworthiness was enhanced by ensuring credibility, transferability, dependability, and confirmability. Ethical principles were upheld throughout the course of this study namely respect for persons, beneficence and justice. All interviews were recorded and transcribed, and the data was analysed using Tesch’s method of data analysis to identify the themes. Three themes came out of the data, namely: Theme 1: Mothers expressed having to navigate a range of physical and psychosocial challenges while caring for their v children; Theme 2: Mothers struggled to perform motherly roles while on TB treatment; Theme 3: Mothers described their relationships with their family, community members and clinic health practitioners. The experiences of the participants were described using direct quotations from the interviews followed by a literature control used to verify the participants’ experiences. Thereafter, the findings were used to develop recommendations to optimise the care and support of mothers on TB treatment who are caring for their children. Four recommendations were developed: Recommendation 1: Prepare and support mothers with TB to care for themselves and their children; Recommendation 2: Assist CHWs and nurses to care and support mothers with TB and their children; Recommendation 3: Prepare and support family members to support mothers with TB and their children and Recommendation 4: Educate community members regarding the needs of mothers with TB. There is limited existing research on mothers who are on TB treatment while caring for their children. This research study helped to fill this gap, particularly in an urban Eastern Cape context. The findings illustrated mothers’ physical and psychosocial challenges, as well their role-related challenges and finally the challenges related to the various spousal, family, community and clinic relationships that influence their experience of caring for their child while on TB treatment. , Thesis (MA) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Mwadiwa, Chiedza
- Date: 2023-12
- Subjects: Caring experiences -- Nelson Mandela Bay , Tuberculosis treatment
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62935 , vital:73071
- Description: Women and mothers have an important role to play as caregivers of their children. However, mothers are often faced with challenges with fulfilling this important role. Many women value the caring role as a mother over other areas of their lives, and for ill women, such as those with tuberculosis (TB) and those on TB treatment, it can be difficult to relinquish maternal responsibility. Indeed, many mothers in South Africa and other low- and middle-income countries develop TB during pregnancy and postpartum because their immune systems are compromised. For a mother who is chronically ill, carrying out a mother’s caregiving role presents a range of challenges. However, few studies have addressed this problem or explored the experiences of such mothers. The purpose of the study was to understand the experiences of mothers who are on TB treatment while caring for their children in order to establish their support needs and thereby develop recommendations to assist CHWs, nurses and nurse managers at primary healthcare (PHC) clinics to provide optimum care to such women. The Socio-Ecological model was used as the theoretical lens to explore the phenomenon under investigation. A qualitative, exploratory-descriptive research design was identified as most suited to respond to the research question. Purposive sampling was used to select both the participants and the clinics in the Nelson Mandela Bay Health District (NMBHD) for the purpose of this study. The population was mothers on TB treatment caring for their children (aged five years or younger) who were attending either one of the two of the largest PHC clinics in Sub-district C in the NMBH. Altogether ten mothers on TB treatment caring for their children took part in individual semi-structured interviews conducted telephonically. Ethical clearance was obtained from Nelson Mandela University and permission was obtained from the Department of Health (DoH), district office, operational managers at the respective clinics, and the participants involved in the study. Trustworthiness was enhanced by ensuring credibility, transferability, dependability, and confirmability. Ethical principles were upheld throughout the course of this study namely respect for persons, beneficence and justice. All interviews were recorded and transcribed, and the data was analysed using Tesch’s method of data analysis to identify the themes. Three themes came out of the data, namely: Theme 1: Mothers expressed having to navigate a range of physical and psychosocial challenges while caring for their v children; Theme 2: Mothers struggled to perform motherly roles while on TB treatment; Theme 3: Mothers described their relationships with their family, community members and clinic health practitioners. The experiences of the participants were described using direct quotations from the interviews followed by a literature control used to verify the participants’ experiences. Thereafter, the findings were used to develop recommendations to optimise the care and support of mothers on TB treatment who are caring for their children. Four recommendations were developed: Recommendation 1: Prepare and support mothers with TB to care for themselves and their children; Recommendation 2: Assist CHWs and nurses to care and support mothers with TB and their children; Recommendation 3: Prepare and support family members to support mothers with TB and their children and Recommendation 4: Educate community members regarding the needs of mothers with TB. There is limited existing research on mothers who are on TB treatment while caring for their children. This research study helped to fill this gap, particularly in an urban Eastern Cape context. The findings illustrated mothers’ physical and psychosocial challenges, as well their role-related challenges and finally the challenges related to the various spousal, family, community and clinic relationships that influence their experience of caring for their child while on TB treatment. , Thesis (MA) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
Experiences of psychological practitioners when working with Isixhosa speaking minors in the Eastern Cape.
- Authors: Matushe, Masakhane
- Date: 2023-12
- Subjects: language barriers -- Eastern Cape , Psychological practitioner
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62884 , vital:73062
- Description: Language barriers continue to pose challenges in education and the health sector where psychological assessments and tests are administered in a language that is different from that of the client. The implication this has on the interpretations of test-taker scores may be bias against those whose first language is not English or Afrikaans, which are two of the primary languages majority of the tests currently used in the South Africa are normed against. This study aimed to explore the implications of the current language repertoires on test-taker performance. This was achieved through exploring the experiences of psychological practitioners who use English language psychological tests on isiXhosa speaking child clients in the Eastern Cape. The methodology followed an exploratory-descriptive, qualitative design, adopting Lincoln and Guba's model of trustworthiness. The researcher employed a qualitative method with an exploratory-descriptive research design, and participants were recruited by utilizing a purposive sampling strategy. Thematic analysis was used as a means of data analysis,and the following themes emerged and were discussed: The use of translators & interpreters, and the challenges thereof; practitioner’s own language proficiencies and limitations; cultutral influence and langaage exposure of clients; Adaptation as well as revision of decolonization of testing measures; and training psychological practitioners. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12
- Authors: Matushe, Masakhane
- Date: 2023-12
- Subjects: language barriers -- Eastern Cape , Psychological practitioner
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/62884 , vital:73062
- Description: Language barriers continue to pose challenges in education and the health sector where psychological assessments and tests are administered in a language that is different from that of the client. The implication this has on the interpretations of test-taker scores may be bias against those whose first language is not English or Afrikaans, which are two of the primary languages majority of the tests currently used in the South Africa are normed against. This study aimed to explore the implications of the current language repertoires on test-taker performance. This was achieved through exploring the experiences of psychological practitioners who use English language psychological tests on isiXhosa speaking child clients in the Eastern Cape. The methodology followed an exploratory-descriptive, qualitative design, adopting Lincoln and Guba's model of trustworthiness. The researcher employed a qualitative method with an exploratory-descriptive research design, and participants were recruited by utilizing a purposive sampling strategy. Thematic analysis was used as a means of data analysis,and the following themes emerged and were discussed: The use of translators & interpreters, and the challenges thereof; practitioner’s own language proficiencies and limitations; cultutral influence and langaage exposure of clients; Adaptation as well as revision of decolonization of testing measures; and training psychological practitioners. , Thesis (Ma) -- Faculty of Health Science, 2023
- Full Text:
- Date Issued: 2023-12