A content analysis of the framing and representation of Black Lives Matter protests by South African mainstream media
- Authors: Manyike, Lerato Gladys
- Date: 2024-10-11
- Subjects: Black lives matter movement , Social movements South Africa , Race in mass media South Africa , Frames (Sociology) , Race discrimination South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465799 , vital:76654
- Description: This study conducted a detailed analysis of 277 headlines using content analysis, focusing on how News24 portrays racial protests, particularly within the Black Lives Matter (BLM) movement. It explored News24's coverage of BLM protests from March to December 2020, uncovering various framing strategies and language nuances in news headlines. The research aimed to identify thematic frames, linguistic patterns, and overall media framing of BLM protests. The findings highlighted different framing strategies, including legitimising, conflict, and delegitimizing frames, along with the impact of descriptive language on audience perceptions. The study concluded that media framing is dynamic, responding to evolving events and public discourse, and provided recommendations for media transparency, diversity in newsrooms, media literacy, and ethical reporting. Future research suggestions include comparative analyses, audience reception studies, and policy impact assessments to deepen understanding and inform strategic interventions in media representations and public discourse on racial justice. Overall, the study contributes valuable insights into media framing practices and their impact on societal perceptions of racial justice issues. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Manyike, Lerato Gladys
- Date: 2024-10-11
- Subjects: Black lives matter movement , Social movements South Africa , Race in mass media South Africa , Frames (Sociology) , Race discrimination South Africa
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/465799 , vital:76654
- Description: This study conducted a detailed analysis of 277 headlines using content analysis, focusing on how News24 portrays racial protests, particularly within the Black Lives Matter (BLM) movement. It explored News24's coverage of BLM protests from March to December 2020, uncovering various framing strategies and language nuances in news headlines. The research aimed to identify thematic frames, linguistic patterns, and overall media framing of BLM protests. The findings highlighted different framing strategies, including legitimising, conflict, and delegitimizing frames, along with the impact of descriptive language on audience perceptions. The study concluded that media framing is dynamic, responding to evolving events and public discourse, and provided recommendations for media transparency, diversity in newsrooms, media literacy, and ethical reporting. Future research suggestions include comparative analyses, audience reception studies, and policy impact assessments to deepen understanding and inform strategic interventions in media representations and public discourse on racial justice. Overall, the study contributes valuable insights into media framing practices and their impact on societal perceptions of racial justice issues. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-10-11
Carnivory submerged: aspects of the ecology and ecophysiology of the aquatic Utricularia stellaris L. fil. (Lentibulariaceae) in South Africa
- Authors: Marais, Alice-Jane
- Date: 2024-10-11
- Subjects: Submerged aquatic vegetation , Bladderworts South Africa , Carnivorous plants , Bladderworts Ecology , Bladderworts Ecophysiology , Plant-microbe relationships
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464473 , vital:76514
- Description: The trapping structures produced by aquatic species of Utricularia have traditionally been interpreted to function as adaptations to capture and break down zooplankton prey, as in other carnivorous plants, to overcome nutrient limitations. However, an increasing number of studies have found that these plants may also rely on benefits derived from living mutualistic microbial communities contained within traps. This study documents aspects of the environmental, growth and physiological characteristics of U. stellaris to inform and to form a basis for future investigation into the plant-microbe interaction. The environmental conditions in which U. stellaris grows were documented to identify potential adverse conditions plants are subject to in situ, from which nutrient limitation was identified as a primary limitation. Plant growth and trapping structures were then assessed to identify possible adaptations of plants to overcome these limitations. The production of trapping structures likely constitutes an adaptive trait, with 30% of total biomass per node allocated to the production of these structures. Based on their capture function, traps may aid plants based on their contents, possibly supplementing plants with nutrients. Although assessments of the habitats of U. stellaris indicate that dissolved CO₂ concentrations in the ambient water are high, CO₂ may still be limiting to the photosynthetic rates of these plants due to viscous water resisting the diffusion of CO₂. The primary site of photosynthesis in U. stellaris is leaves and trap tissue’s contribution to photosynthetic output is negligible. U. stellaris plants are subject to CO₂ limitations in natural pond conditions, making the substantial allocation of resources to non-photosynthetic trapping tissue even more costly. Therefore, benefits gained from trapping structures are likely to be derived from trap contents; having ruled out the possibility that the trap tissue itself is photosynthetic. Trap contents of U. stellaris were assessed. The proportion of traps containing living microbial communities greatly exceeded the proportion containing zooplankton prey. In addition, these communities were found to be diverse, stable, and self-sustaining. These results suggest that trapping structures may be beneficial for both the carnivorous capture of prey and the housing of living microbial communities. These results indicate the plantmicrobe interaction in U. stellaris warrants further study. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Marais, Alice-Jane
- Date: 2024-10-11
- Subjects: Submerged aquatic vegetation , Bladderworts South Africa , Carnivorous plants , Bladderworts Ecology , Bladderworts Ecophysiology , Plant-microbe relationships
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464473 , vital:76514
- Description: The trapping structures produced by aquatic species of Utricularia have traditionally been interpreted to function as adaptations to capture and break down zooplankton prey, as in other carnivorous plants, to overcome nutrient limitations. However, an increasing number of studies have found that these plants may also rely on benefits derived from living mutualistic microbial communities contained within traps. This study documents aspects of the environmental, growth and physiological characteristics of U. stellaris to inform and to form a basis for future investigation into the plant-microbe interaction. The environmental conditions in which U. stellaris grows were documented to identify potential adverse conditions plants are subject to in situ, from which nutrient limitation was identified as a primary limitation. Plant growth and trapping structures were then assessed to identify possible adaptations of plants to overcome these limitations. The production of trapping structures likely constitutes an adaptive trait, with 30% of total biomass per node allocated to the production of these structures. Based on their capture function, traps may aid plants based on their contents, possibly supplementing plants with nutrients. Although assessments of the habitats of U. stellaris indicate that dissolved CO₂ concentrations in the ambient water are high, CO₂ may still be limiting to the photosynthetic rates of these plants due to viscous water resisting the diffusion of CO₂. The primary site of photosynthesis in U. stellaris is leaves and trap tissue’s contribution to photosynthetic output is negligible. U. stellaris plants are subject to CO₂ limitations in natural pond conditions, making the substantial allocation of resources to non-photosynthetic trapping tissue even more costly. Therefore, benefits gained from trapping structures are likely to be derived from trap contents; having ruled out the possibility that the trap tissue itself is photosynthetic. Trap contents of U. stellaris were assessed. The proportion of traps containing living microbial communities greatly exceeded the proportion containing zooplankton prey. In addition, these communities were found to be diverse, stable, and self-sustaining. These results suggest that trapping structures may be beneficial for both the carnivorous capture of prey and the housing of living microbial communities. These results indicate the plantmicrobe interaction in U. stellaris warrants further study. , Thesis (MSc) -- Faculty of Science, Botany, 2024
- Full Text:
- Date Issued: 2024-10-11
Towards an Extensible Generic Agent-Based Simulator for Mammals
- Carse, Stephen, Bradshaw, Karen L
- Authors: Carse, Stephen , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475296 , vital:77793 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9856380"
- Description: Modelling tools are widely used by national parks, both within South Africa and in countries around the world. The modelling of animal behaviour, particularly in South Africa and other African countries, is well established. These models, however, tend to be developed with one particular application and species in mind and are not reusable in other scenarios, requiring further development work for the addition of another species. This paper presents an approach towards developing an agent-based generic system that simulates a range of mammal behaviours by building a set of core behaviours that can be parameterised according to the needs of each species. The system uses XML notation for the definition of a species and provides a GUI tool that produces the XML required to simulate a species and set up the initial animals present in the simulation. Various feedback tools allow the simulation to be examined and analysed in detail to ascertain the success of the simulation of the mammal behaviours and those behaviours' adaptation to various different species.
- Full Text:
- Date Issued: 2015
- Authors: Carse, Stephen , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475296 , vital:77793 , xlink:href="https://ieeexplore.ieee.org/abstract/document/9856380"
- Description: Modelling tools are widely used by national parks, both within South Africa and in countries around the world. The modelling of animal behaviour, particularly in South Africa and other African countries, is well established. These models, however, tend to be developed with one particular application and species in mind and are not reusable in other scenarios, requiring further development work for the addition of another species. This paper presents an approach towards developing an agent-based generic system that simulates a range of mammal behaviours by building a set of core behaviours that can be parameterised according to the needs of each species. The system uses XML notation for the definition of a species and provides a GUI tool that produces the XML required to simulate a species and set up the initial animals present in the simulation. Various feedback tools allow the simulation to be examined and analysed in detail to ascertain the success of the simulation of the mammal behaviours and those behaviours' adaptation to various different species.
- Full Text:
- Date Issued: 2015
Problem-solving ability of first year CS students: A case study and intervention
- Marais, Craig, Bradshaw, Karen L
- Authors: Marais, Craig , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475235 , vital:77787
- Description: This paper reports the findings of computational thinking research undertaken to develop problem-solving skills in first year computer science students. Through the use of pre-and post-tests, statistical results are presented showing the definite acquisition of problem-solving skills by the students after completing the introductory first year computer science course. These skills are argued to be both innate in some students and acquired in others. By identifying the component skills required and presenting a step-by-step approach to teaching problem solving, this research aims to provide a method for actively instilling these skills in learners who lack them.
- Full Text:
- Date Issued: 2015
- Authors: Marais, Craig , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475235 , vital:77787
- Description: This paper reports the findings of computational thinking research undertaken to develop problem-solving skills in first year computer science students. Through the use of pre-and post-tests, statistical results are presented showing the definite acquisition of problem-solving skills by the students after completing the introductory first year computer science course. These skills are argued to be both innate in some students and acquired in others. By identifying the component skills required and presenting a step-by-step approach to teaching problem solving, this research aims to provide a method for actively instilling these skills in learners who lack them.
- Full Text:
- Date Issued: 2015
Determining the difficulty of accelerating problems on a GPU
- Tristram, Dale, Bradshaw, Karen L
- Authors: Tristram, Dale , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475208 , vital:77784
- Description: General-purpose computation on graphics processing units (GPGPU) has great potential to accelerate many scientific models and algorithms. However, since some problems are considerably more difficult to accelerate than others, ascertaining the effort required to accelerate a particular problem is challenging. Through the acceleration of three typical scientific problems, seven problem attributes have been identified to assist in the evaluation of the difficulty of accelerating a problem on a GPU. These attributes are inherent parallelism, branch divergence, problem size, required computational parallelism, memory access pattern regularity, data transfer overhead, and thread cooperation. Using these attributes as difficulty indicators, an initial problem difficulty classification framework has been created that aids in evaluating GPU acceleration difficulty. The difficulty estimates obtained by applying the classification framework to the three case studies correlate well with the actual effort expended in accelerating each problem.
- Full Text:
- Date Issued: 2014
- Authors: Tristram, Dale , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475208 , vital:77784
- Description: General-purpose computation on graphics processing units (GPGPU) has great potential to accelerate many scientific models and algorithms. However, since some problems are considerably more difficult to accelerate than others, ascertaining the effort required to accelerate a particular problem is challenging. Through the acceleration of three typical scientific problems, seven problem attributes have been identified to assist in the evaluation of the difficulty of accelerating a problem on a GPU. These attributes are inherent parallelism, branch divergence, problem size, required computational parallelism, memory access pattern regularity, data transfer overhead, and thread cooperation. Using these attributes as difficulty indicators, an initial problem difficulty classification framework has been created that aids in evaluating GPU acceleration difficulty. The difficulty estimates obtained by applying the classification framework to the three case studies correlate well with the actual effort expended in accelerating each problem.
- Full Text:
- Date Issued: 2014
A multi-biometric feature-fusion framework for improved uni-modal and multi-modal human identification
- Brown, Dane L, Bradshaw, Karen L
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473696 , vital:77673 , xlink:href="https://ieeexplore.ieee.org/abstract/document/7568927"
- Description: The lack of multi-biometric fusion guidelines at the feature-level are addressed in this work. A feature-fusion framework is geared toward improving human identification accuracy for both single and multiple biometrics. The foundation of the framework is the improvement over a state-of-the-art uni-modal biometric verification system, which is extended into a multi-modal identification system. A novel multi-biometric system is thus designed based on the framework, which serves as fusion guidelines for multi-biometric applications that fuse at the feature-level. This framework was applied to the face and fingerprint to achieve a 91.11% recognition accuracy when using only a single training sample. Furthermore, an accuracy of 99.69% was achieved when using five training samples.
- Full Text:
- Date Issued: 2016
- Authors: Brown, Dane L , Bradshaw, Karen L
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/473696 , vital:77673 , xlink:href="https://ieeexplore.ieee.org/abstract/document/7568927"
- Description: The lack of multi-biometric fusion guidelines at the feature-level are addressed in this work. A feature-fusion framework is geared toward improving human identification accuracy for both single and multiple biometrics. The foundation of the framework is the improvement over a state-of-the-art uni-modal biometric verification system, which is extended into a multi-modal identification system. A novel multi-biometric system is thus designed based on the framework, which serves as fusion guidelines for multi-biometric applications that fuse at the feature-level. This framework was applied to the face and fingerprint to achieve a 91.11% recognition accuracy when using only a single training sample. Furthermore, an accuracy of 99.69% was achieved when using five training samples.
- Full Text:
- Date Issued: 2016
HADEDA: A Concurrent Music Synthesis Project for the XMOS startKIT
- Dibley, James, Bradshaw, Karen L
- Authors: Dibley, James , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475224 , vital:77786 , xlink:href="https://doi.org/10.13140/2.1.1352.3201"
- Description: The HADEDA (Highly Adaptive Device Emitting Digitally-synthesised Audio) project implements a softwaredefined audio synthesiser with stored musical sequences and real-time synthesis controls, using the XMOS startKIT low-cost development platform. This paper describes the design and implementation of the project as a practical demonstration of XMOS technology. We also demonstrate the use of XC programming techniques and the xTIMEcomposer development tools to build and test a concurrent real-time embedded application easily.
- Full Text:
- Date Issued: 2014
- Authors: Dibley, James , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475224 , vital:77786 , xlink:href="https://doi.org/10.13140/2.1.1352.3201"
- Description: The HADEDA (Highly Adaptive Device Emitting Digitally-synthesised Audio) project implements a softwaredefined audio synthesiser with stored musical sequences and real-time synthesis controls, using the XMOS startKIT low-cost development platform. This paper describes the design and implementation of the project as a practical demonstration of XMOS technology. We also demonstrate the use of XC programming techniques and the xTIMEcomposer development tools to build and test a concurrent real-time embedded application easily.
- Full Text:
- Date Issued: 2014
Drowning in data, thirsty for information and starved for understanding: A biodiversity information hub for cooperative environmental monitoring in South Africa
- MacFadyen, Sandra, Allsopp, Nicky, Altwegg, Res, Archibald, Sally, Botha, Judith, Bradshaw, Karen L, Carruthers, Jane, De Klerk, Helen, de Vos, Alta, Distiller, Greg, Foord, Stefan, Freitag-Ronaldson, Stefanie, Gibbs, Richard, Hamer, Michelle, Landi, Pietro, MacFayden, Duncan, Manuel, Jeffrey, Midgley, Guy F, Moncrieff, Glenn, Munch, Zahn, Mutanga, Onisimo, Sershen, Nenguda, Rendani, Ngwenya, Mzabalazo, Parker, Daniel M, Peel, Mike, Power, John, Pretorius, Joachim, Ramdhani, Syd, Robertson, Mark P, Rushworth, Ian, Skowno, Andrew, Slingsby, Jasper, Turner, Andrew, Visser, Vernon, van Wageningen, Gerhard, Hui, Cang
- Authors: MacFadyen, Sandra , Allsopp, Nicky , Altwegg, Res , Archibald, Sally , Botha, Judith , Bradshaw, Karen L , Carruthers, Jane , De Klerk, Helen , de Vos, Alta , Distiller, Greg , Foord, Stefan , Freitag-Ronaldson, Stefanie , Gibbs, Richard , Hamer, Michelle , Landi, Pietro , MacFayden, Duncan , Manuel, Jeffrey , Midgley, Guy F , Moncrieff, Glenn , Munch, Zahn , Mutanga, Onisimo , Sershen , Nenguda, Rendani , Ngwenya, Mzabalazo , Parker, Daniel M , Peel, Mike , Power, John , Pretorius, Joachim , Ramdhani, Syd , Robertson, Mark P , Rushworth, Ian , Skowno, Andrew , Slingsby, Jasper , Turner, Andrew , Visser, Vernon , van Wageningen, Gerhard , Hui, Cang
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415624 , vital:71271 , xlink:href="https://doi.org/10.1016/j.biocon.2022.109736"
- Description: The world is firmly cemented in a notitian age (Latin: notitia, meaning data) – drowning in data, yet thirsty for information and the synthesis of knowledge into understanding. As concerns over biodiversity declines escalate, the volume, diversity and speed at which new environmental and ecological data are generated has increased exponentially. Data availability primes the research and discovery engine driving biodiversity conservation. South Africa (SA) is poised to become a world leader in biodiversity conservation. However, continent-wide resource limitations hamper the establishment of inclusive technologies and robust platforms and tools for biodiversity informatics. In this perspectives piece, we bring together the opinions of 37 co-authors from 20 different departments, across 10 SA universities, 7 national and provincial conservation research agencies, and various institutes and private conservation, research and management bodies, to develop a way forward for biodiversity informatics in SA. We propose the development of a SA Biodiversity Informatics Hub and describe the essential components necessary for its design, implementation and sustainability. We emphasise the importance of developing a culture of cooperation, collaboration and interoperability among custodians of biodiversity data to establish operational workflows for data synthesis. However, our biggest challenges are misgivings around data sharing and multidisciplinary collaboration.
- Full Text:
- Date Issued: 2022
- Authors: MacFadyen, Sandra , Allsopp, Nicky , Altwegg, Res , Archibald, Sally , Botha, Judith , Bradshaw, Karen L , Carruthers, Jane , De Klerk, Helen , de Vos, Alta , Distiller, Greg , Foord, Stefan , Freitag-Ronaldson, Stefanie , Gibbs, Richard , Hamer, Michelle , Landi, Pietro , MacFayden, Duncan , Manuel, Jeffrey , Midgley, Guy F , Moncrieff, Glenn , Munch, Zahn , Mutanga, Onisimo , Sershen , Nenguda, Rendani , Ngwenya, Mzabalazo , Parker, Daniel M , Peel, Mike , Power, John , Pretorius, Joachim , Ramdhani, Syd , Robertson, Mark P , Rushworth, Ian , Skowno, Andrew , Slingsby, Jasper , Turner, Andrew , Visser, Vernon , van Wageningen, Gerhard , Hui, Cang
- Date: 2022
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/415624 , vital:71271 , xlink:href="https://doi.org/10.1016/j.biocon.2022.109736"
- Description: The world is firmly cemented in a notitian age (Latin: notitia, meaning data) – drowning in data, yet thirsty for information and the synthesis of knowledge into understanding. As concerns over biodiversity declines escalate, the volume, diversity and speed at which new environmental and ecological data are generated has increased exponentially. Data availability primes the research and discovery engine driving biodiversity conservation. South Africa (SA) is poised to become a world leader in biodiversity conservation. However, continent-wide resource limitations hamper the establishment of inclusive technologies and robust platforms and tools for biodiversity informatics. In this perspectives piece, we bring together the opinions of 37 co-authors from 20 different departments, across 10 SA universities, 7 national and provincial conservation research agencies, and various institutes and private conservation, research and management bodies, to develop a way forward for biodiversity informatics in SA. We propose the development of a SA Biodiversity Informatics Hub and describe the essential components necessary for its design, implementation and sustainability. We emphasise the importance of developing a culture of cooperation, collaboration and interoperability among custodians of biodiversity data to establish operational workflows for data synthesis. However, our biggest challenges are misgivings around data sharing and multidisciplinary collaboration.
- Full Text:
- Date Issued: 2022
Service learning based environmental health promotion activities for pharmacy students: educating young on the safe disposal of medicines and used sharps
- Srinivas, Sunitha C, Paphitis, Sharli, Ncomanzi, A.S, Tandlich, Roman, Bradshaw, Karen L
- Authors: Srinivas, Sunitha C , Paphitis, Sharli , Ncomanzi, A.S , Tandlich, Roman , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475255 , vital:77788
- Description: The objective of this study was to investigate the effects of a service-learning based environmental health promotion exhibit in raising awareness of safe disposal of medicines and used sharps during the 2014 National Science Festival in South Africa. The study design utilised a computer-based quiz, an information poster, an interactive model and a take-home information leaflet on the safe disposal of medicines and used sharps which were developed by students and staff in the faculty of pharmacy at Rhodes University. Predominantly school students attended the exhibit and took part in a quiz. 413 participants took part in the environmental health promotion activity, with 91% of the participating learners attending schools in the Eastern Cape Province. significant improvement (p is less than 0.001). Moreover, the results show significant gender differences for both the pre- and post-intervention mean scores. The environmental health promotion project was successful in raising awareness of the safe and appropriate disposal of medicines and used sharps by highlighting the dangers associated with their incorrect disposal, both to the environment and eventually to humans. Similar continuous health promotion activities are essential for sustainable effectiveness in the transformation of individual and communal actions in South Africa for the safe disposal of medicines and used sharps.
- Full Text:
- Date Issued: 2015
- Authors: Srinivas, Sunitha C , Paphitis, Sharli , Ncomanzi, A.S , Tandlich, Roman , Bradshaw, Karen L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475255 , vital:77788
- Description: The objective of this study was to investigate the effects of a service-learning based environmental health promotion exhibit in raising awareness of safe disposal of medicines and used sharps during the 2014 National Science Festival in South Africa. The study design utilised a computer-based quiz, an information poster, an interactive model and a take-home information leaflet on the safe disposal of medicines and used sharps which were developed by students and staff in the faculty of pharmacy at Rhodes University. Predominantly school students attended the exhibit and took part in a quiz. 413 participants took part in the environmental health promotion activity, with 91% of the participating learners attending schools in the Eastern Cape Province. significant improvement (p is less than 0.001). Moreover, the results show significant gender differences for both the pre- and post-intervention mean scores. The environmental health promotion project was successful in raising awareness of the safe and appropriate disposal of medicines and used sharps by highlighting the dangers associated with their incorrect disposal, both to the environment and eventually to humans. Similar continuous health promotion activities are essential for sustainable effectiveness in the transformation of individual and communal actions in South Africa for the safe disposal of medicines and used sharps.
- Full Text:
- Date Issued: 2015
Yield curve and business cycle dynamics in South Africa: new evidence from a Markov switching model
- Authors: Rotich, Mercyline Chepkemoi
- Date: 2024-04-03
- Subjects: Yield curve , Business cycles South Africa , Markov processes , Recessions South Africa , Multivariate analysis
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/434739 , vital:73101
- Description: Globally, several empirical studies have demonstrated the ability of the yield spread to predict a recession in a country. In South Africa, previous studies have not only shown the yield curve's predictive power but have further demonstrated that it outperforms other commonly used variables, such as the growth rate of real money supply, changes in stock prices, and the index of leading economic indicators. However, some recent studies have shown that the yield spread (the spread between 10-year bonds and 3-month Treasury bills) gave false signals of recession. In this study, we explore the possible reasons for the false signals of the yield spread by addressing the following questions. Does the yield spread used matter? Does the measure of the business cycle used matter? And do the estimation techniques used matter? To address the first question, unlike the previous studies, this paper uses four different yield spreads- depicting short-term, medium-term, and long-term government bonds against the backdrop of a changing structure of bond holding, which reflects the increasing risk eversion of investors in South Africa. Second, the paper used different measures of business cycles, namely industrial production index, lagging, coincident, and leading economic indicators. The empirical models were estimated using both univariate and multivariate Markov switching models. As economic theory suggests, the univariate Markov switching model was used to determine if each variable exhibits a significant regime switching. The multivariate Markov switching model was estimated for each business cycle and yield spread variable, with each of the other variables serving as a non-switching explanatory variable, thereby addressing potential endogeneity concerns and the predictive power of the explanatory variable. Finally, the multivariate Markov switching model was estimated for three monthly sample periods, a full sample for 1986 to 2022, and two sub-samples – 1986 to 2009 and 2010 to 2022. This analysis consistently reveals significant regime-switching behavior across all the series thus, affirming the superiority of the regime switching model over the standard model used in previous studies. By analyzing the transition probabilities and the expected durations between these regimes, we find that including the spreads in the business cycle model improves the models’ predictability, with the medium-term bonds spread performing better than the usual long-term spread. The smoothed regime probability of the best-performing models is compared with the SARB recession dates; the two closely resemble each other, proving that the Markov switching model can help predict the turning points in the business cycle in South Africa. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-04-03
- Authors: Rotich, Mercyline Chepkemoi
- Date: 2024-04-03
- Subjects: Yield curve , Business cycles South Africa , Markov processes , Recessions South Africa , Multivariate analysis
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/434739 , vital:73101
- Description: Globally, several empirical studies have demonstrated the ability of the yield spread to predict a recession in a country. In South Africa, previous studies have not only shown the yield curve's predictive power but have further demonstrated that it outperforms other commonly used variables, such as the growth rate of real money supply, changes in stock prices, and the index of leading economic indicators. However, some recent studies have shown that the yield spread (the spread between 10-year bonds and 3-month Treasury bills) gave false signals of recession. In this study, we explore the possible reasons for the false signals of the yield spread by addressing the following questions. Does the yield spread used matter? Does the measure of the business cycle used matter? And do the estimation techniques used matter? To address the first question, unlike the previous studies, this paper uses four different yield spreads- depicting short-term, medium-term, and long-term government bonds against the backdrop of a changing structure of bond holding, which reflects the increasing risk eversion of investors in South Africa. Second, the paper used different measures of business cycles, namely industrial production index, lagging, coincident, and leading economic indicators. The empirical models were estimated using both univariate and multivariate Markov switching models. As economic theory suggests, the univariate Markov switching model was used to determine if each variable exhibits a significant regime switching. The multivariate Markov switching model was estimated for each business cycle and yield spread variable, with each of the other variables serving as a non-switching explanatory variable, thereby addressing potential endogeneity concerns and the predictive power of the explanatory variable. Finally, the multivariate Markov switching model was estimated for three monthly sample periods, a full sample for 1986 to 2022, and two sub-samples – 1986 to 2009 and 2010 to 2022. This analysis consistently reveals significant regime-switching behavior across all the series thus, affirming the superiority of the regime switching model over the standard model used in previous studies. By analyzing the transition probabilities and the expected durations between these regimes, we find that including the spreads in the business cycle model improves the models’ predictability, with the medium-term bonds spread performing better than the usual long-term spread. The smoothed regime probability of the best-performing models is compared with the SARB recession dates; the two closely resemble each other, proving that the Markov switching model can help predict the turning points in the business cycle in South Africa. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2024
- Full Text:
- Date Issued: 2024-04-03
Accelerating a hydrological uncertainty ensemble model using graphics processing units (GPUs)
- Tristram, Dale, Hughes, Denis A, Bradshaw, Karen L
- Authors: Tristram, Dale , Hughes, Denis A , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475173 , vital:77781 , xlink:href="https://doi.org/10.1016/j.cageo.2013.07.011"
- Description: The practical application of hydrological uncertainty models that are designed to generate multiple ensembles can be severely restricted by the available computer processing power and thus, the time taken to generate the results. CPU clusters can help in this regard, but are often costly to use continuously and maintain, causing scientists to look elsewhere for speed improvements. The use of powerful graphics processing units (GPUs) for application acceleration has become a recent trend, owing to their low cost per FLOP, and their highly parallel and throughput-oriented architecture, which makes them ideal for many scientific applications. However, programming these devices efficiently is non-trivial, seemingly making their use impractical for many researchers. In this study, we investigate whether redesigning the CPU code of an adapted Pitman rainfall-runoff uncertainty model is necessary to obtain a satisfactory speedup on GPU devices. A twelvefold speedup over a multithreaded CPU implementation was achieved by using a modern GPU with minimal changes to the model code. This success leads us to believe that redesigning code for the GPU is not always necessary to obtain a worthwhile speedup.
- Full Text:
- Date Issued: 2014
- Authors: Tristram, Dale , Hughes, Denis A , Bradshaw, Karen L
- Date: 2014
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475173 , vital:77781 , xlink:href="https://doi.org/10.1016/j.cageo.2013.07.011"
- Description: The practical application of hydrological uncertainty models that are designed to generate multiple ensembles can be severely restricted by the available computer processing power and thus, the time taken to generate the results. CPU clusters can help in this regard, but are often costly to use continuously and maintain, causing scientists to look elsewhere for speed improvements. The use of powerful graphics processing units (GPUs) for application acceleration has become a recent trend, owing to their low cost per FLOP, and their highly parallel and throughput-oriented architecture, which makes them ideal for many scientific applications. However, programming these devices efficiently is non-trivial, seemingly making their use impractical for many researchers. In this study, we investigate whether redesigning the CPU code of an adapted Pitman rainfall-runoff uncertainty model is necessary to obtain a satisfactory speedup on GPU devices. A twelvefold speedup over a multithreaded CPU implementation was achieved by using a modern GPU with minimal changes to the model code. This success leads us to believe that redesigning code for the GPU is not always necessary to obtain a worthwhile speedup.
- Full Text:
- Date Issued: 2014
A battle of values: analysing the changing attitudes towards African refugees in Europe
- Authors: Mannion, Megan Kate
- Date: 2024-04-04
- Subjects: Refugees Africa , Refugees Public opinion Europe , Cosmopolitanism , Communitarianism , Racism against Black people , Xenophobia in mass media
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435525 , vital:73165
- Description: Cosmopolitanism is a moral perspective that stresses the importance that every human being is an equal and ultimate unit of moral concern. These principles make cosmopolitanism more concerned for and accommodative towards outsiders to a political community. Against the abstraction and universalism of cosmopolitanism, communitarianism emphasizes the role communities play in shaping our individual identities and sees it as justified that the interests and well-being of community members receive priority over those of outsiders. Both these value systems are present in Europe. The question is about which direction the trend has moved in recent decades. This dissertation examines the changing values that inform attitudes toward African refugees in Europe to get at this issue. Have attitudes towards African refugees shifted in a cosmopolitan or a communitarian direction in recent decades? This dissertation examines newspaper articles from The Guardian between 1990 and 2022 to track changes in value. The analysis of these articles uncovered that communitarian values were the most prevalent and stayed the most prevalent from 1990 to 2022. These findings indicate that communitarian values are higher than cosmopolitan values regarding African refugees within the general European context. These findings add to the growing body of knowledge regarding attitude shifts, and they provide a timeline for value changes that can help predict future values and be used in future comparative studies. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2024
- Full Text:
- Date Issued: 2024-04-04
- Authors: Mannion, Megan Kate
- Date: 2024-04-04
- Subjects: Refugees Africa , Refugees Public opinion Europe , Cosmopolitanism , Communitarianism , Racism against Black people , Xenophobia in mass media
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435525 , vital:73165
- Description: Cosmopolitanism is a moral perspective that stresses the importance that every human being is an equal and ultimate unit of moral concern. These principles make cosmopolitanism more concerned for and accommodative towards outsiders to a political community. Against the abstraction and universalism of cosmopolitanism, communitarianism emphasizes the role communities play in shaping our individual identities and sees it as justified that the interests and well-being of community members receive priority over those of outsiders. Both these value systems are present in Europe. The question is about which direction the trend has moved in recent decades. This dissertation examines the changing values that inform attitudes toward African refugees in Europe to get at this issue. Have attitudes towards African refugees shifted in a cosmopolitan or a communitarian direction in recent decades? This dissertation examines newspaper articles from The Guardian between 1990 and 2022 to track changes in value. The analysis of these articles uncovered that communitarian values were the most prevalent and stayed the most prevalent from 1990 to 2022. These findings indicate that communitarian values are higher than cosmopolitan values regarding African refugees within the general European context. These findings add to the growing body of knowledge regarding attitude shifts, and they provide a timeline for value changes that can help predict future values and be used in future comparative studies. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2024
- Full Text:
- Date Issued: 2024-04-04
The feasibility of task-shifting prolonged exposure for Primary Care (PE-PC) for PTSD within a low resource community in the Eastern Cape
- Shabangu, Princess Noxolo Nonhlanhla
- Authors: Shabangu, Princess Noxolo Nonhlanhla
- Date: 2024-04-04
- Subjects: Task shifting , Prolonged exposure therapy , Post-traumatic stress disorder , Primary health care , Community psychiatry South Africa Eastern Cape
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435479 , vital:73161
- Description: Although high levels of trauma exposure potentiate an alarming prevalence of PTSD, increasing the need for trauma-focused treatment, the South African health system is unable to care for the population. The South African healthcare system contains a range of systemic and structural inefficiencies, including suboptimal care and shortages of healthcare professionals. PE-PC offers a resource-constrained mental healthcare system solution by integrating an evidence-based intervention (EBI) in primary care settings. Likewise, the present study acknowledges the ratio of mental healthcare professionals to patients in low- and middle-income countries (LMIC). It explores task shifting to expand mental healthcare to primary care settings. The study follows qualitative healthcare design research to explore the experiences and perceptions of the two cohorts of trauma support workers (TSW) from Rhode University and the Joza community in Makhanda. The feasibility of the PE-PC intervention in Makhanda was illustrated through the data obtained from the TSWs' experiences and perceptions of the intervention's utility. The present study presents an essential contribution to the sparse research conducted on treating PTSD in LMIC with shortages in healthcare professionals. The thematic findings look at the trauma support workers (TSWs) role, including some of its challenges, to explore the feasibility of interventions. Some of the themes highlighted unpack the perceived utility of task-shifting in low-resource contexts, the limitations thereof and considerations for future research. Notwithstanding the challenges, the data from the present study indicates that PE-PC can be feasibly task-shifted in low-resource contexts such as Makhanda. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-04-04
- Authors: Shabangu, Princess Noxolo Nonhlanhla
- Date: 2024-04-04
- Subjects: Task shifting , Prolonged exposure therapy , Post-traumatic stress disorder , Primary health care , Community psychiatry South Africa Eastern Cape
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/435479 , vital:73161
- Description: Although high levels of trauma exposure potentiate an alarming prevalence of PTSD, increasing the need for trauma-focused treatment, the South African health system is unable to care for the population. The South African healthcare system contains a range of systemic and structural inefficiencies, including suboptimal care and shortages of healthcare professionals. PE-PC offers a resource-constrained mental healthcare system solution by integrating an evidence-based intervention (EBI) in primary care settings. Likewise, the present study acknowledges the ratio of mental healthcare professionals to patients in low- and middle-income countries (LMIC). It explores task shifting to expand mental healthcare to primary care settings. The study follows qualitative healthcare design research to explore the experiences and perceptions of the two cohorts of trauma support workers (TSW) from Rhode University and the Joza community in Makhanda. The feasibility of the PE-PC intervention in Makhanda was illustrated through the data obtained from the TSWs' experiences and perceptions of the intervention's utility. The present study presents an essential contribution to the sparse research conducted on treating PTSD in LMIC with shortages in healthcare professionals. The thematic findings look at the trauma support workers (TSWs) role, including some of its challenges, to explore the feasibility of interventions. Some of the themes highlighted unpack the perceived utility of task-shifting in low-resource contexts, the limitations thereof and considerations for future research. Notwithstanding the challenges, the data from the present study indicates that PE-PC can be feasibly task-shifted in low-resource contexts such as Makhanda. , Thesis (MA) -- Faculty of Humanities, Psychology, 2024
- Full Text:
- Date Issued: 2024-04-04
Carbonylation of cyclohexene with carbon dioxide (CO2) using transition metals as heterogeneous and homogeneous catalysts
- Authors: Sekaleli, Bafokeng Thabelo
- Date: 2024-10-11
- Subjects: Carbonylation , Carbon dioxide , Catalysts , Transition metals , Cyclohexene
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464565 , vital:76522
- Description: From a green chemistry perspective, carbon dioxide (CO2) emerges as an appealing C1 synthon, given its abundance in the atmosphere and cost-effectiveness. Many essential chemicals for daily life are derived from fossilized carbon sources like coal, petroleum, and natural gas. However, the by-product of these processes, CO2, poses environmental risks when excessively emitted as a greenhouse gas. Achieving a balance between carbon emissions and removal is crucial to address environmental concerns surrounding CO2. Utilizing CO2 as a C1 source in organic synthesis holds promise for mitigating this balance in the long term. Combining CO2 with other underutilized fine chemicals, such as alkanes, alkenes, and alkynes, to produce more valuable platform chemicals presents an economically viable strategy due to carbon dioxide’s abundance, low cost, and recyclability. Despite its simplicity, CO2's high thermodynamic stability and low kinetic reactivity, owing to its highly oxidized state, pose challenges to its use as a feedstock. Overcoming these hurdles requires catalysts to enhance CO2 reactivity. Our work focuses on developing and employing catalytic systems capable of activating CO2 as a C1 synthon in reactions with cyclohexene and a reducing agent to yield carboxylic acids or esters. In one approach, we have developed heterogeneous catalyst systems comprising transition metals (Au, Fe, Ni, Ru) supported on metal oxide (TiO2). Characterization techniques such as TEM, EDX, UV-Vis, BET, and XRD were used to study the properties of these materials. The catalysts were evaluated in a reaction involving cyclohexene, CO2, and H2O. In another approach, we explored the use of cyclo-tris(tetracarbonylruthenium) [Ru3(CO)12] as a homogeneous catalyst in a reaction involving cyclohexene, methanol, and CO2 in the presence of an ionic liquid, 1-Butyl-3-methylimidazolium chloride ([BMIM]+Cl-). 1H NMR and ATR-FT-IR were utilized to characterize [BMIM]+Cl-. The reaction product was characterised utilizing GC-MS. Upon seeing that Ru3(CO)12 changes color from orange to black when exposed to heat, an investigation was undertaken on the kind of transformations that the catalyst undergoes. This investigation was carried out with the hopes of finding the structures that could be resulting from Ru3(CO)12 during the reaction and their significance to it. The orange and black Ru complexes were characterized utilizing DSC, TGA, ATR-FT-IR and PXRD. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Sekaleli, Bafokeng Thabelo
- Date: 2024-10-11
- Subjects: Carbonylation , Carbon dioxide , Catalysts , Transition metals , Cyclohexene
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464565 , vital:76522
- Description: From a green chemistry perspective, carbon dioxide (CO2) emerges as an appealing C1 synthon, given its abundance in the atmosphere and cost-effectiveness. Many essential chemicals for daily life are derived from fossilized carbon sources like coal, petroleum, and natural gas. However, the by-product of these processes, CO2, poses environmental risks when excessively emitted as a greenhouse gas. Achieving a balance between carbon emissions and removal is crucial to address environmental concerns surrounding CO2. Utilizing CO2 as a C1 source in organic synthesis holds promise for mitigating this balance in the long term. Combining CO2 with other underutilized fine chemicals, such as alkanes, alkenes, and alkynes, to produce more valuable platform chemicals presents an economically viable strategy due to carbon dioxide’s abundance, low cost, and recyclability. Despite its simplicity, CO2's high thermodynamic stability and low kinetic reactivity, owing to its highly oxidized state, pose challenges to its use as a feedstock. Overcoming these hurdles requires catalysts to enhance CO2 reactivity. Our work focuses on developing and employing catalytic systems capable of activating CO2 as a C1 synthon in reactions with cyclohexene and a reducing agent to yield carboxylic acids or esters. In one approach, we have developed heterogeneous catalyst systems comprising transition metals (Au, Fe, Ni, Ru) supported on metal oxide (TiO2). Characterization techniques such as TEM, EDX, UV-Vis, BET, and XRD were used to study the properties of these materials. The catalysts were evaluated in a reaction involving cyclohexene, CO2, and H2O. In another approach, we explored the use of cyclo-tris(tetracarbonylruthenium) [Ru3(CO)12] as a homogeneous catalyst in a reaction involving cyclohexene, methanol, and CO2 in the presence of an ionic liquid, 1-Butyl-3-methylimidazolium chloride ([BMIM]+Cl-). 1H NMR and ATR-FT-IR were utilized to characterize [BMIM]+Cl-. The reaction product was characterised utilizing GC-MS. Upon seeing that Ru3(CO)12 changes color from orange to black when exposed to heat, an investigation was undertaken on the kind of transformations that the catalyst undergoes. This investigation was carried out with the hopes of finding the structures that could be resulting from Ru3(CO)12 during the reaction and their significance to it. The orange and black Ru complexes were characterized utilizing DSC, TGA, ATR-FT-IR and PXRD. , Thesis (MSc) -- Faculty of Science, Chemistry, 2024
- Full Text:
- Date Issued: 2024-10-11
The reproductive biology of warty sea cucumber, Neostichopus grammatus Clark (Holothuroidea: Echinodermata) under natural and integrated multi-trophic aquaculture (IMTA) conditions in the Eastern Cape Province, South Africa
- Authors: Senekal, Heleen Ester
- Date: 2024-10-11
- Subjects: Sea cucumbers South Africa Eastern Cape , Sea cucumbers Reproduction , Gonads , Gonadosomatic Index , Integrated aquaculture , Abalone culture , Sea cucumbers Effect of temperature on , Marine sediments
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464451 , vital:76512
- Description: This study investigated the reproductive cycle of the warty sea cucumber, Neostichopus grammatus, in the wild and in a farming environment, to test its suitability for co-culture with abalone Haliotis midae in an IMTA system. The research formed part of a broader EU H2020 program, Aquavitae, and was conducted at Wild Coast Abalone in South Africa. The study investigated several environmental parameters, such as temperature, day length, and substrate, to determine if these have any effects on the gonadal development and reproductive cycle. The natural gametogenic cycle of wild warty sea cucumbers was determined by monitoring the Gonadosomatic Index (GI) values monthly for a period of 16 months. The GI index was validated by means of other maturity assessment techniques including measurement of the size and colour of the gonads, oocyte diameter measurements and gonad histology sections. Wild collected sea cucumbers were maintained in abalone farm rearing tanks on a diet of abalone feed and faecal waste for a period of 10 months, with GI values being determined monthly. The wild and farmed sea cucumber GI data was correlated with environmental parameters. Seasonal water temperature was strongly correlated with the GI values of wild warty sea cucumbers, suggesting that water temperature likely influences gonadal development. Sea cucumbers matured sexually during colder months (May to September) and spawned from September to February, during summer. The results of oocyte measurements, macroscopic and microscopic analyses, and histological analyses in combination with the GI values, provides a practical indicator of sexual maturity for captive breeding purposes. Farmed warty sea cucumbers followed the same annual reproductive cycle as wild sea cucumbers, however they came into spawning condition approximately one month later than wild conspecifics. As the farm water temperature was significantly higher than the ambient ocean water temperature, it was hypothesised that this may have affected the gonadal development of the farmed sea cucumbers. Furthermore, the farm-reared sea cucumbers lost weight and condition, indicating a nutritional deficiency. Previous studies indicated that the presence of a sand sediment facilitated the assimilation of organic detrital matter by sea cucumbers. An additional trial was thus set up to determine the effect of a sand sediment and cooler ambient temperature on the growth and gonadal development of the warty sea cucumbers. The growth and GI values of sea cucumbers in the cool water treatment did not differ significantly from the ambient temperature control groups. However, the addition of a sand substrate to the sea cucumber tanks had a significant positive growth effect on sea cucumber body mass and GI values. Sea cucumbers fed a diet of abalone waste material on the sand substrate exhibited final average GI values of 2.99 % (SE ±0.56). In contrast, sea cucumbers kept in bare tanks and only received abalone waste as food had significantly lower average GI values of 1.36 % (SE±0.2). This suggests that the provision of a sand sustrate in sea cucumber rearing containers is essential for the adequate nutrition and gonadal development. The results of this study indicate that the warty sea cucumber is a promising candidate for inlcusion in an IMTA system with South African perlemoen abalone. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2024
- Full Text:
- Date Issued: 2024-10-11
- Authors: Senekal, Heleen Ester
- Date: 2024-10-11
- Subjects: Sea cucumbers South Africa Eastern Cape , Sea cucumbers Reproduction , Gonads , Gonadosomatic Index , Integrated aquaculture , Abalone culture , Sea cucumbers Effect of temperature on , Marine sediments
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/464451 , vital:76512
- Description: This study investigated the reproductive cycle of the warty sea cucumber, Neostichopus grammatus, in the wild and in a farming environment, to test its suitability for co-culture with abalone Haliotis midae in an IMTA system. The research formed part of a broader EU H2020 program, Aquavitae, and was conducted at Wild Coast Abalone in South Africa. The study investigated several environmental parameters, such as temperature, day length, and substrate, to determine if these have any effects on the gonadal development and reproductive cycle. The natural gametogenic cycle of wild warty sea cucumbers was determined by monitoring the Gonadosomatic Index (GI) values monthly for a period of 16 months. The GI index was validated by means of other maturity assessment techniques including measurement of the size and colour of the gonads, oocyte diameter measurements and gonad histology sections. Wild collected sea cucumbers were maintained in abalone farm rearing tanks on a diet of abalone feed and faecal waste for a period of 10 months, with GI values being determined monthly. The wild and farmed sea cucumber GI data was correlated with environmental parameters. Seasonal water temperature was strongly correlated with the GI values of wild warty sea cucumbers, suggesting that water temperature likely influences gonadal development. Sea cucumbers matured sexually during colder months (May to September) and spawned from September to February, during summer. The results of oocyte measurements, macroscopic and microscopic analyses, and histological analyses in combination with the GI values, provides a practical indicator of sexual maturity for captive breeding purposes. Farmed warty sea cucumbers followed the same annual reproductive cycle as wild sea cucumbers, however they came into spawning condition approximately one month later than wild conspecifics. As the farm water temperature was significantly higher than the ambient ocean water temperature, it was hypothesised that this may have affected the gonadal development of the farmed sea cucumbers. Furthermore, the farm-reared sea cucumbers lost weight and condition, indicating a nutritional deficiency. Previous studies indicated that the presence of a sand sediment facilitated the assimilation of organic detrital matter by sea cucumbers. An additional trial was thus set up to determine the effect of a sand sediment and cooler ambient temperature on the growth and gonadal development of the warty sea cucumbers. The growth and GI values of sea cucumbers in the cool water treatment did not differ significantly from the ambient temperature control groups. However, the addition of a sand substrate to the sea cucumber tanks had a significant positive growth effect on sea cucumber body mass and GI values. Sea cucumbers fed a diet of abalone waste material on the sand substrate exhibited final average GI values of 2.99 % (SE ±0.56). In contrast, sea cucumbers kept in bare tanks and only received abalone waste as food had significantly lower average GI values of 1.36 % (SE±0.2). This suggests that the provision of a sand sustrate in sea cucumber rearing containers is essential for the adequate nutrition and gonadal development. The results of this study indicate that the warty sea cucumber is a promising candidate for inlcusion in an IMTA system with South African perlemoen abalone. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2024
- Full Text:
- Date Issued: 2024-10-11
Volcano correlations for the reactivity of surface-confined cobalt N4-macrocyclics for the electrocatalytic oxidation of 2-mercaptoacetate
- Claußen, Jan A, Ochoa, Gonzalo, Páez, Maritza, Costamagno, Juan, Gulppi, Miguel, Nyokong, Tebello, Bedioui, Fethi, Zagal, José H
- Authors: Claußen, Jan A , Ochoa, Gonzalo , Páez, Maritza , Costamagno, Juan , Gulppi, Miguel , Nyokong, Tebello , Bedioui, Fethi , Zagal, José H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268688 , vital:54222 , xlink:href="https://doi.org/10.1007/s10008-007-0336-y"
- Description: We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin larger than Co–tetrasulfonatotetraphenylporphyrin larger than Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine. Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation for the interaction of the thiol with the active site.
- Full Text:
- Date Issued: 2008
- Authors: Claußen, Jan A , Ochoa, Gonzalo , Páez, Maritza , Costamagno, Juan , Gulppi, Miguel , Nyokong, Tebello , Bedioui, Fethi , Zagal, José H
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/268688 , vital:54222 , xlink:href="https://doi.org/10.1007/s10008-007-0336-y"
- Description: We have investigated the electrocatalytic activity of several substituted and unsubstituted cobalt–phthalocyanines of substituted tetraphenyl porphyrins and of vitamin B12, for the electro-oxidation of 2-mercaptoacetate, with the complexes pre-adsorbed on a pyrolytic graphite electrode. Several N4-macrocyclic were used to have a wide variety of Co(II)/(I) formal potentials. The electrocatalytic activity, measured as current at constant potential, increases with the Co(II)/(I) redox potential for porphyrins as Co–pentafluorotetraphenylporphyrin larger than Co–tetrasulfonatotetraphenylporphyrin larger than Co-2,2′,2″,2‴tetra-aminotetraphenylporphyrin and decreases for cobalt phthalocyanines as Co-3,4-octaethylhexyloxyphthalocyanine > Co–octamethoxyphthalocyanine > Co–tetranitrophthalocyanine Co–tetraaminophthalocyanine > Co–unsubstituted phthalocyanine > Co–tetrasulfonatophthalocyanine > Co–perfluorinated phthalocyanine. Vitamin B12 exhibits the maximum activity. A correlation of log I (at constant potential) versus the Co(II)/(I) formal potential of the catalysts gives a volcano curve. This clearly shows that the search for better catalysts for this reaction point to those N4-macrocyclic complexes with Co(II)/(I) formal potentials close to −0.84 V versus SCE, which correspond to an optimum situation for the interaction of the thiol with the active site.
- Full Text:
- Date Issued: 2008
Tuning the redox properties of metalloporphyrin-and metallophthalocyanine-based molecular electrodes for the highest electrocatalytic activity in the oxidation of thiols
- Bedioui, Fethi, Griveau, Sophie, Nyokong, Tebello, Appleby, A John, Caro, Claudia A, Gulppi, Miguel, Ochoa, Gonzalo, Zagal, José H
- Authors: Bedioui, Fethi , Griveau, Sophie , Nyokong, Tebello , Appleby, A John , Caro, Claudia A , Gulppi, Miguel , Ochoa, Gonzalo , Zagal, José H
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283988 , vital:56009 , xlink:href="https://doi.org/10.1039/B618767F"
- Description: In this work we discuss different approaches for achieving electrodes modified with N4 macrocyclic complexes for the catalysis of the electrochemical oxidation of thiols. These approaches involve adsorption, electropolymerization and molecular anchoring using self assembled monolayers. We also discuss the parameters that determine the reactivity of these complexes. Catalytic activity is associated with the nature of the central metal, redox potentials and Hammett parameters of substituents on the ligand. Correlations between catalytic activity (log i at constant E) and the redox potential of catalysts for complexes of Cr, Mn, Fe, Co, Ni and Cu are linear with an increase of activity for more positive redox potentials. For a great variety complexes bearing the same metal center (Co) correlations between log i and Eo′ of the Co(II)/Co(I) couple have the shape of an unsymmetric volcano. This indicates that the potential of the Co(II)/Co(I) couple can be tuned using the appropiate ligand to achieve maximum catalytic activity. Maximum activity probably corresponds to a ΔG of adsorption of the thiol on the Co center equal to zero, and to a coverage of active sites by the thiol equal to 0.5.
- Full Text:
- Date Issued: 2007
- Authors: Bedioui, Fethi , Griveau, Sophie , Nyokong, Tebello , Appleby, A John , Caro, Claudia A , Gulppi, Miguel , Ochoa, Gonzalo , Zagal, José H
- Date: 2007
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/283988 , vital:56009 , xlink:href="https://doi.org/10.1039/B618767F"
- Description: In this work we discuss different approaches for achieving electrodes modified with N4 macrocyclic complexes for the catalysis of the electrochemical oxidation of thiols. These approaches involve adsorption, electropolymerization and molecular anchoring using self assembled monolayers. We also discuss the parameters that determine the reactivity of these complexes. Catalytic activity is associated with the nature of the central metal, redox potentials and Hammett parameters of substituents on the ligand. Correlations between catalytic activity (log i at constant E) and the redox potential of catalysts for complexes of Cr, Mn, Fe, Co, Ni and Cu are linear with an increase of activity for more positive redox potentials. For a great variety complexes bearing the same metal center (Co) correlations between log i and Eo′ of the Co(II)/Co(I) couple have the shape of an unsymmetric volcano. This indicates that the potential of the Co(II)/Co(I) couple can be tuned using the appropiate ligand to achieve maximum catalytic activity. Maximum activity probably corresponds to a ΔG of adsorption of the thiol on the Co center equal to zero, and to a coverage of active sites by the thiol equal to 0.5.
- Full Text:
- Date Issued: 2007
Trypanosoma brucei J protein 2 is a stress inducible and essential Hsp40
- Ludewig, Michael H, Boshoff, Aileen, Horn, David, Blatch, Gregory L
- Authors: Ludewig, Michael H , Boshoff, Aileen , Horn, David , Blatch, Gregory L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/476618 , vital:77942 , xlink:href="https://doi.org/10.1016/j.biocel.2014.12.016"
- Description: Hsp40 proteins (also known as DnaJ or J proteins) serve as co-chaperones for Hsp70, but also display evidence of independent chaperone function. Furthermore, certain Hsp40s have been shown to be stress-inducible and essential. Trypanosomatids display a remarkable diversification of Hsp40 proteins, with numerous distinct Hsp40-like proteins encoded in the Trypanosoma brucei genome. This study investigated the role of one of the six T. brucei Type I Hsp40s, T. brucei J protein 2 (Tbj2). We found that Tbj2 was heat stress-inducible, and that knockdown using RNA interference resulted in a severe growth defect under normal growth temperatures. Furthermore, a green fluorescent protein (GFP)-Tbj2 fusion protein was found to be localized to the cytosol of T. brucei. Taken together, these data suggest that Tbj2 is not functionally equivalent to the other five Type I Hsp40s, and that it is an essential, cytosolic, and stress-inducible chaperone, potentially playing an important role in protein biogenesis in T. brucei.
- Full Text:
- Date Issued: 2015
- Authors: Ludewig, Michael H , Boshoff, Aileen , Horn, David , Blatch, Gregory L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/476618 , vital:77942 , xlink:href="https://doi.org/10.1016/j.biocel.2014.12.016"
- Description: Hsp40 proteins (also known as DnaJ or J proteins) serve as co-chaperones for Hsp70, but also display evidence of independent chaperone function. Furthermore, certain Hsp40s have been shown to be stress-inducible and essential. Trypanosomatids display a remarkable diversification of Hsp40 proteins, with numerous distinct Hsp40-like proteins encoded in the Trypanosoma brucei genome. This study investigated the role of one of the six T. brucei Type I Hsp40s, T. brucei J protein 2 (Tbj2). We found that Tbj2 was heat stress-inducible, and that knockdown using RNA interference resulted in a severe growth defect under normal growth temperatures. Furthermore, a green fluorescent protein (GFP)-Tbj2 fusion protein was found to be localized to the cytosol of T. brucei. Taken together, these data suggest that Tbj2 is not functionally equivalent to the other five Type I Hsp40s, and that it is an essential, cytosolic, and stress-inducible chaperone, potentially playing an important role in protein biogenesis in T. brucei.
- Full Text:
- Date Issued: 2015
SPACES Project ARS AfricaE–Adaptive Resilience of Southern African ecosystems
- Falge, E M, Brümmer, Christian, Schmullius, Christiane, Hüttich, C, Scholes, Robert J, Midgley, Guy F, Hickler, Thomas, Scheiter, Simon, Twine, Wayne, Bradshaw, Karen L, Lück, W, Lenfers, Ulfia A, Thiel-Clemen, T, Mafukute, Mukelabai, Kutsch, Werner L
- Authors: Falge, E M , Brümmer, Christian , Schmullius, Christiane , Hüttich, C , Scholes, Robert J , Midgley, Guy F , Hickler, Thomas , Scheiter, Simon , Twine, Wayne , Bradshaw, Karen L , Lück, W , Lenfers, Ulfia A , Thiel-Clemen, T , Mafukute, Mukelabai , Kutsch, Werner L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475274 , vital:77791
- Description: Nowadays, many semi-arid ecosystems are affected by at least two different kinds of disturbances: land use (change) and climate change. Based on this, it can be hypothesized that even very resilient ecosystems may not return to their initial state after disturbance, but will rather adapt to a new steady-state. We name this phenomenon "Adaptive Resilience of Ecosystems" and use it as base for the research concept of ARS AfricaE. This project wants to go beyond older approaches that only describe structural changes in savannas and their drivers. It employs functional aspects, such as the investigation of biogeochemical cycles, but also targets a deeper understanding of the functional consequences of ecosystem changes caused by multiple disturbances, and defines "degradation" as a sustained loss in the broad set of ecosystem services, i.e. a decrease in natural capital. To achieve this goal, the project will • create a network of research clusters (with natural and altered vegetation) along an aridity gradient in the Greater Karoo, Kruger National Park in South Africa, and Kataba Forest Reserve in Zambia • link biogeochemical functions with ecosystem structure, diversity of species and eco-physiological properties • describe ecosystem disturbance (and recovery) in terms of ecosystem function such as carbon balance components and water use efficiency • build an individual-based model to predict ecosystem dynamics under (post) disturbance managements • combine this model with long-term landscape dynamic information derived from remote sensing and aerial photography • develop sustainable management strategies for disturbed ecosystems and land use change.
- Full Text:
- Date Issued: 2015
- Authors: Falge, E M , Brümmer, Christian , Schmullius, Christiane , Hüttich, C , Scholes, Robert J , Midgley, Guy F , Hickler, Thomas , Scheiter, Simon , Twine, Wayne , Bradshaw, Karen L , Lück, W , Lenfers, Ulfia A , Thiel-Clemen, T , Mafukute, Mukelabai , Kutsch, Werner L
- Date: 2015
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/475274 , vital:77791
- Description: Nowadays, many semi-arid ecosystems are affected by at least two different kinds of disturbances: land use (change) and climate change. Based on this, it can be hypothesized that even very resilient ecosystems may not return to their initial state after disturbance, but will rather adapt to a new steady-state. We name this phenomenon "Adaptive Resilience of Ecosystems" and use it as base for the research concept of ARS AfricaE. This project wants to go beyond older approaches that only describe structural changes in savannas and their drivers. It employs functional aspects, such as the investigation of biogeochemical cycles, but also targets a deeper understanding of the functional consequences of ecosystem changes caused by multiple disturbances, and defines "degradation" as a sustained loss in the broad set of ecosystem services, i.e. a decrease in natural capital. To achieve this goal, the project will • create a network of research clusters (with natural and altered vegetation) along an aridity gradient in the Greater Karoo, Kruger National Park in South Africa, and Kataba Forest Reserve in Zambia • link biogeochemical functions with ecosystem structure, diversity of species and eco-physiological properties • describe ecosystem disturbance (and recovery) in terms of ecosystem function such as carbon balance components and water use efficiency • build an individual-based model to predict ecosystem dynamics under (post) disturbance managements • combine this model with long-term landscape dynamic information derived from remote sensing and aerial photography • develop sustainable management strategies for disturbed ecosystems and land use change.
- Full Text:
- Date Issued: 2015
Was Myriophyllum spicatum L.(Haloragaceae) recently introduced to South Africa from Eurasia?
- Weyl, Philip S R, Thum, Ryan A, Moody, M L, Newman, R M, Coetzee, Julie A
- Authors: Weyl, Philip S R , Thum, Ryan A , Moody, M L , Newman, R M , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425463 , vital:72242 , xlink:href="https://doi.org/10.1016/j.aquabot.2015.09.003"
- Description: There is debate over the native or exotic status of Myriophyllum spicatum L. (Haloragaceae) in South Africa, which has important implications for developing and implementing management strategies. The aim of this study was to determine if M. spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear ribosomal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations. For both these DNA markers, the South African populations were distinct from Eurasian populations, but always stemmed from a European origin. The data suggest that South African and European M. spicatum share a common ancestor, however the divergence of both markers are characteristic of a long period of isolation rather than a recent introduction from Europe. The genetic data from this study suggest that M. spicatum has not been introduced recently, but is most likely a native component of the South African flora.
- Full Text:
- Date Issued: 2016
- Authors: Weyl, Philip S R , Thum, Ryan A , Moody, M L , Newman, R M , Coetzee, Julie A
- Date: 2016
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/425463 , vital:72242 , xlink:href="https://doi.org/10.1016/j.aquabot.2015.09.003"
- Description: There is debate over the native or exotic status of Myriophyllum spicatum L. (Haloragaceae) in South Africa, which has important implications for developing and implementing management strategies. The aim of this study was to determine if M. spicatum was recently introduced from Eurasia by reconstructing the genetic relationships between South African and Eurasian M. spicatum using both a nuclear ribosomal (ITS1-5.8S-ITS2-26S) and a chloroplast intron (trnQ-rps16) sequence from 40 populations. For both these DNA markers, the South African populations were distinct from Eurasian populations, but always stemmed from a European origin. The data suggest that South African and European M. spicatum share a common ancestor, however the divergence of both markers are characteristic of a long period of isolation rather than a recent introduction from Europe. The genetic data from this study suggest that M. spicatum has not been introduced recently, but is most likely a native component of the South African flora.
- Full Text:
- Date Issued: 2016