A trait-based approach to identify indicators for measuring rocky reef ecosystem condition in South Africa
- Authors: Smit, Kaylee
- Date: 2020
- Subjects: Environmental management -- Evaluation , Environmental monitoring -- Methodology Marine ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49292 , vital:41618
- Description: An important yet challenging task for effective ecosystem-based management of marine ecosystems is the reliable measurement and monitoring of changes in ecosystem condition. In South Africa, the National Biodiversity Assessment (NBA) has relied on cumulative pressure mapping, based on the calculation of cumulative impact scores, as a proxy for measures of marine ecosystem condition. While this method is practical for broad scale assessments where ecological data are lacking, there is a need to groundtruth this approach at local scales using in-situ data. The aim of this thesis was to identify potential indicators that can be used to measure the ecosystem condition of subtidal rocky reefs on the East coast of South Africa to groundtruth national pressure-based condition assessments. This thesis constituted the first attempt to conduct a comprehensive assessment of rocky reef ecosystem condition to validate national pressure-based assessments in South Africa. Based on a comprehensive literature review, a traits-based approach was selected to ensure that ecosystem structure and function were included in condition measurements. Fish and benthic community data were collected using baited remote underwater stereo-video systems (144 video samples) from the Natal Shelf ecoregion. Sampling spanned a gradient of low to high human pressures, which incorporated an effective Marine Protected Area (to define reference conditions), as well as areas exposed to intermediate levels of human pressures and a highly impacted area offshore of a large metropolitan port city. Structural and functional indicators were compared among localities and suitable functional indicators were aggregated into multimetric indices (MMIs) to provide an integrated measurement of ecosystem condition. Approximately 840 benthic biota and 10 400 fish (representing 176 identified fish species) were counted. Results showed that functional indicators, particularly size-based ones, were more effective at detecting changes in ecosystem condition compared with structural indicators based on taxonomy. Reefs in good ecological condition had a higher biomass of target species and a higher proportion of large predatory fish with more adults, compared with impacted areas. Benthic communities, however, appeared less responsive to cumulative pressures. The MMIs, using fish and benthic community data, were used to compare condition categories with those from the NBA. Results showed that the pressure-based assessments provided a reasonable proxy of broad patterns of rocky reef ecosystem condition. However, fine-scale discrepancies between results from the data-driven approach versus the proxy method suggested that broad-scale proxies might overestimate condition in some areas and underestimate it in others. To build on these results, the applicability of structural and functional indicators and MMIs were tested using an independent stereo-BRUVs dataset from the Agulhas Shelf ecoregion. Findings showed that not all MPAs were in good ecological condition compared with adjacent impacted areas, as was estimated by the NBA. However, there is a need to improve the quality of trait data and to test indicators and indices in other ecoregions, ecosystem types and in response to a broader range of improved pressure data. Furthermore, there is a need to apply innovative research to guide the calculation of thresholds for condition categories to advance condition assessments.
- Full Text:
- Date Issued: 2020
- Authors: Smit, Kaylee
- Date: 2020
- Subjects: Environmental management -- Evaluation , Environmental monitoring -- Methodology Marine ecology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/49292 , vital:41618
- Description: An important yet challenging task for effective ecosystem-based management of marine ecosystems is the reliable measurement and monitoring of changes in ecosystem condition. In South Africa, the National Biodiversity Assessment (NBA) has relied on cumulative pressure mapping, based on the calculation of cumulative impact scores, as a proxy for measures of marine ecosystem condition. While this method is practical for broad scale assessments where ecological data are lacking, there is a need to groundtruth this approach at local scales using in-situ data. The aim of this thesis was to identify potential indicators that can be used to measure the ecosystem condition of subtidal rocky reefs on the East coast of South Africa to groundtruth national pressure-based condition assessments. This thesis constituted the first attempt to conduct a comprehensive assessment of rocky reef ecosystem condition to validate national pressure-based assessments in South Africa. Based on a comprehensive literature review, a traits-based approach was selected to ensure that ecosystem structure and function were included in condition measurements. Fish and benthic community data were collected using baited remote underwater stereo-video systems (144 video samples) from the Natal Shelf ecoregion. Sampling spanned a gradient of low to high human pressures, which incorporated an effective Marine Protected Area (to define reference conditions), as well as areas exposed to intermediate levels of human pressures and a highly impacted area offshore of a large metropolitan port city. Structural and functional indicators were compared among localities and suitable functional indicators were aggregated into multimetric indices (MMIs) to provide an integrated measurement of ecosystem condition. Approximately 840 benthic biota and 10 400 fish (representing 176 identified fish species) were counted. Results showed that functional indicators, particularly size-based ones, were more effective at detecting changes in ecosystem condition compared with structural indicators based on taxonomy. Reefs in good ecological condition had a higher biomass of target species and a higher proportion of large predatory fish with more adults, compared with impacted areas. Benthic communities, however, appeared less responsive to cumulative pressures. The MMIs, using fish and benthic community data, were used to compare condition categories with those from the NBA. Results showed that the pressure-based assessments provided a reasonable proxy of broad patterns of rocky reef ecosystem condition. However, fine-scale discrepancies between results from the data-driven approach versus the proxy method suggested that broad-scale proxies might overestimate condition in some areas and underestimate it in others. To build on these results, the applicability of structural and functional indicators and MMIs were tested using an independent stereo-BRUVs dataset from the Agulhas Shelf ecoregion. Findings showed that not all MPAs were in good ecological condition compared with adjacent impacted areas, as was estimated by the NBA. However, there is a need to improve the quality of trait data and to test indicators and indices in other ecoregions, ecosystem types and in response to a broader range of improved pressure data. Furthermore, there is a need to apply innovative research to guide the calculation of thresholds for condition categories to advance condition assessments.
- Full Text:
- Date Issued: 2020
A transportation management framework for the Polokwane local municipality during Zion Christian Church (ZCC) Easter weekend pilgrimage
- Authors: Mathebula, Andrew Mabila
- Date: 2020
- Subjects: Transportation -- Management , Urban transportation -- Planning Urban transportation -- Management Christian pilgrims and pilgrimages
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46152 , vital:39509
- Description: The study investigated the impact of the high volume of vehicular traffic on pilgrims and the community during the Zion Christian Church (ZCC) Easter weekend pilgrimage. The researcher adopted an interpretivist research philosophy, and thus attempted to understand policy, planning, and management of the ZCC Easter pilgrimage through meanings that municipal officials assign to them. The study employed the action research approach by collaborating with the Polokwane Local Municipality (PLM) with a view to evolving lasting solutions to traffic congestion during the Easter weekend. The researchers used the seven-step model proposed by Van Tonder and Dietrichsen (Van Tonder and Dietrichsen, 2008). The justification of the model is that it is aligned with the action research model of Organisational Development (OD). It requires that a diagnosis process should be collaborative and participative towards offering solutions to organisational challenges as opposed to imposing a unilateral theoretical generated solution. This model also fits the ontological stance of the researchers which assumes that reality is co-constructed through engagement with other stakeholders. The researcher conducted semi-structured individual and focus groups discussion (FGD) using openended guides. The data from the informants were collected until a point of saturation. In addition to facilitation FGD discussion, the researcher made his own personal reflection of the participatory action research (PAR). A content analysis method was used to synthesise the qualitative data. The contents were extracted from transcribed interviews. The researcher carefully reviewed the notes several times and coded the notes independently. After that, the researcher coded the codes with each other for any potential contradiction. These codes were converted into themes and sub-themes. The qualitative content analysis process, led by the researcher, was both inductive and deductive. Prior to the inductive process, the researcher listened carefully to the audio recordings transcriptions to get a general understanding of participants’ experiences. The findings indicate that the South African transportation planning approach is ossified and divorced from reality. There is a lacuna to address peak traffic challenges during the Easter weekend and the festive season. It is notable that the government-led seasonal road safety campaigns such as ‘Arrive Alive’ are curiously inadequate to address peak traffic and road accidents challenges in South Africa during the ZCC Easter pilgrimage. The transportation management framework for the PLM as well as a peak traffic standard were developed as part of the study recommendations. These recommendations augur a shift to transport planning in South Africa.
- Full Text:
- Date Issued: 2020
- Authors: Mathebula, Andrew Mabila
- Date: 2020
- Subjects: Transportation -- Management , Urban transportation -- Planning Urban transportation -- Management Christian pilgrims and pilgrimages
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/46152 , vital:39509
- Description: The study investigated the impact of the high volume of vehicular traffic on pilgrims and the community during the Zion Christian Church (ZCC) Easter weekend pilgrimage. The researcher adopted an interpretivist research philosophy, and thus attempted to understand policy, planning, and management of the ZCC Easter pilgrimage through meanings that municipal officials assign to them. The study employed the action research approach by collaborating with the Polokwane Local Municipality (PLM) with a view to evolving lasting solutions to traffic congestion during the Easter weekend. The researchers used the seven-step model proposed by Van Tonder and Dietrichsen (Van Tonder and Dietrichsen, 2008). The justification of the model is that it is aligned with the action research model of Organisational Development (OD). It requires that a diagnosis process should be collaborative and participative towards offering solutions to organisational challenges as opposed to imposing a unilateral theoretical generated solution. This model also fits the ontological stance of the researchers which assumes that reality is co-constructed through engagement with other stakeholders. The researcher conducted semi-structured individual and focus groups discussion (FGD) using openended guides. The data from the informants were collected until a point of saturation. In addition to facilitation FGD discussion, the researcher made his own personal reflection of the participatory action research (PAR). A content analysis method was used to synthesise the qualitative data. The contents were extracted from transcribed interviews. The researcher carefully reviewed the notes several times and coded the notes independently. After that, the researcher coded the codes with each other for any potential contradiction. These codes were converted into themes and sub-themes. The qualitative content analysis process, led by the researcher, was both inductive and deductive. Prior to the inductive process, the researcher listened carefully to the audio recordings transcriptions to get a general understanding of participants’ experiences. The findings indicate that the South African transportation planning approach is ossified and divorced from reality. There is a lacuna to address peak traffic challenges during the Easter weekend and the festive season. It is notable that the government-led seasonal road safety campaigns such as ‘Arrive Alive’ are curiously inadequate to address peak traffic and road accidents challenges in South Africa during the ZCC Easter pilgrimage. The transportation management framework for the PLM as well as a peak traffic standard were developed as part of the study recommendations. These recommendations augur a shift to transport planning in South Africa.
- Full Text:
- Date Issued: 2020
A tribute to you
- Ndlebe-September, Thobeka Veronica
- Authors: Ndlebe-September, Thobeka Veronica
- Date: 2020
- Subjects: South African fiction (English) -- 21st century , South African fiction (English) -- History and criticism , Short stories, South African (English) -- 21st century , Xhosa fiction -- 21st century , Xhosa fiction -- History and criticism , Short stories, Xhosa -- 21st century , Diaries -- Authorship
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/144989 , vital:38398
- Description: My collection of short stories reflects my interest in narrative biblical fiction, allegorical stories about people and nature that resonate with our daily lives. I have been greatly influenced by writers such as Joel Matlou, Flannery O’Connor, Barry Gifford, Miriam Tladi and Leah Harris amongst others. I have also been captivated by fairy tales and folk tales, and also the work of isiXhosa writers such as S. E. K. Mqhayi, Madiponi Masenya, and Hulisani Ramantswana. I have discovered that I can borrow certain styles and forms of writing to enhance my own stories which are situated within ‘local’ contexts such as education, poverty, employment, the body, life and death.
- Full Text:
- Date Issued: 2020
- Authors: Ndlebe-September, Thobeka Veronica
- Date: 2020
- Subjects: South African fiction (English) -- 21st century , South African fiction (English) -- History and criticism , Short stories, South African (English) -- 21st century , Xhosa fiction -- 21st century , Xhosa fiction -- History and criticism , Short stories, Xhosa -- 21st century , Diaries -- Authorship
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/144989 , vital:38398
- Description: My collection of short stories reflects my interest in narrative biblical fiction, allegorical stories about people and nature that resonate with our daily lives. I have been greatly influenced by writers such as Joel Matlou, Flannery O’Connor, Barry Gifford, Miriam Tladi and Leah Harris amongst others. I have also been captivated by fairy tales and folk tales, and also the work of isiXhosa writers such as S. E. K. Mqhayi, Madiponi Masenya, and Hulisani Ramantswana. I have discovered that I can borrow certain styles and forms of writing to enhance my own stories which are situated within ‘local’ contexts such as education, poverty, employment, the body, life and death.
- Full Text:
- Date Issued: 2020
A Veblenian Dichotomy re-examination of labour brokerage and South African labour market functionality
- Authors: Haaketa, Bernadatte Tina
- Date: 2020
- Subjects: Veblen, Thorstein, 1857-1929 , Contracting out -- South Africa , Temporary employment -- South Africa , Industrial relations -- South Africa , Labor supply -- South Africa , Labor supply -- Effect of technological innovations on -- South Africa , Manpower policy -- South Africa , Labor market -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/168446 , vital:41583
- Description: Labour markets ar ound the world have witnessed a great change in labour relations. The introduction of globa lisation, increased competition and technological advancements has caused business organisations to change their employment methods. While trying to survive and remain profitable, employers have adopted a new form of triangular employment relationship. Thi s form of employment relationship known as labour broking and which forms part of the Temporary Employment Services (TES) involves a relationship between the worker, labour agent (broker) and a client c ompany. Although it may seem like a good strategy for business organisations, the change in employment relationships has had negative effects and contributed to labour market dysfunctionalities . This has resulted in critics of labour broking calling or an end in labour broking and supporters of labour broking asking for better regulation of the industry. Labour markets are me When it comes to analysing labour broking and its impact on labour market functionality in South Africa. Scholars and analysts such as Budlender ( 2013 ) and Bhorat, Lil enstein, Oosthuizen , and Thornton ( 2016 ) have used the Neoclassical , New Institutional Economics and Marxist approach es. The current views on labour broking and the current schools of thought fail to look at the underlying behavioural aspect of labour brokers and the client c ompanies. Hence making it easy for labour brokers and their client companies to continue with their unscrupulous activities. However, this t hesis adapted the Veblenian Dichotomy framework which focuses on understanding the role of the evolutionary proce ss and the role of institutions in shaping economic behaviour. The Veblenian dichotomy shows that power plays an important role in how labour markets are run. Similarly, behaviour also influences the manner in which labour brokers and client companies trea t workers. And lastly the Veblenian dichotomy shows that in order for the industry to be run better there has to be change in the behaviour and cultu re of the labour brokers and client companies . This view allows for deeper analysis of the reasons for the flour ishing nature of labour broking and the rationale behind the behaviour of economic players and attempts to provide solutions on how labour brok ing can be correctly administered in South Africa. The Veblenian Dichotomy categorises institutions into t wo sets, namely the ceremonial institutions and instrumental institutions. Where Ceremonial institutions are said to be institutions that foster the interests of business such as profitability and earning of free income, even if there is no corresponding i ncrease in production. While Instrumental institutions, usually working through the influence of technology, address the interests of the common pers on and the labourer as well as business (Waller, 1982; Foster, 1981; Veblen, 1919). These two systems of va lues and institutions are antagonistic and the relative strength of one to the other determines economic outcomes and in whose interests the outcomes would be (Waller, 1982; Foster, 1981; Veblen, 1919). The Veblenian Dichotomy further looks at ceremonial encapsulation which occurs when ceremonial systems prevail over instrumental systems. Ceremonial encapsulation presents the hypothesis that the insti tutional structure will absorb new technology only to the extent that it can do so without disrupting the e xisting value structure (Waller, 1987; Bush, 1979.) The thesis use d various sources , such as working papers, public hearings, court cases, trade union submissions, integrated reports from companies, employee submissions and media publications on the debate about labour broking whether labour broking and applied the Interpretative Phenomenological Analysi s (IPA) research approach, in the process of data collection and analysis . The thesis further applied thematic analysis to derive themes that would be used to analyse the impact of labour broking on labour market functionality in South Africa. The emergent themes and subthemes were Exploitative lab our relations subthemes; job Insecurity, increased financial burden and no skills development. The second theme was; Competitive advantage and the subthemes were; i ncreased profits and organisational efficiency. The third theme was l abour market efficiency and the subthemes were. E mployment creation and labour market flexibility. And, the last theme was a mbiguous l abour regulation s with subthemes; n o freedom of association and a tool for circumventing labour regulations . Lastly, Tool’s (1994) criteria of j udgement for institutional adjustments was used to evaluate the emergent themes and to evaluate the impact of l abour broking on the overall welfare of individuals, which includes determining whether employees in the TES sector gain skills and improved stan dards of living. The findings of the research the TES sector is characterised by ceremonial values. Ceremonial values (as mentioned in section 3.3) are those values that are warranted by the ways of life that prescribe status and hierarchies and unpleasant distinctions to apply value and status on other people (Bush, 1987, 1988; Ayres, 1967). Thus changing the way in which labour brokers conduct themselves or handle labour broking activities would prove to be difficult . T he power that is mostly used in TES employment sectors is condign power. Condign power is explained as the form of power that is predominantly used in ceremonially encapsulated markets. And it involves making use of punishment or fear in order to get people to do something. This is because w orkers in the TES sector are forced to submit to conditions that they would not normally have submitted to if t hey did not have a fear of losing their jobs. This supports existing literature which shows that in the TES sector, TES employers use force and p ower in order to get the workers to do something, and this results in a master - servant relationship between the employer and the employee. Furthermore, the protests that erupt in the TES sector agree with Marxist theory which notes that the frustrations in the way workers are treated would result in a revolution of the working class against the employers. However, now, workers have not been able to overcome the employers and take over the industry. In addition to what current literature says, the research found that some managers make use of labour broking as a way of manifesting their exploitative characteristics on the labour market, thus creating information asymmetries in order to advance their own personal needs. Situations such as these reve al characteristics of opportunistic behaviour, which is perpetuated by the imperfect flow of information. This means th at the market is imperfect, and imperfect markets are characteristics of dysfunctional labour markets. The research also found that it i s the South African Constitution that protects labour brokers and client companies from accounting for the unfair treatm ent of workers. Labour brokers and client companies rely on the South African Constitution to defend them when it comes to banning labou r broking. This is because section 22 of the Constitution talks about the right of every individual to trade freely in S outh Africa (Kutumela, 2015). When institutional adjustments do not meet the requirements of the progressive criteria, it means they are regressive. Based on the data that was collected and the responses and remarks of the workers, trade unions, and trade union federations, it can be said that TES employment and labour broking hinders labour market functionality. Hence, it can be concluded that, due to the characteristics mentioned, labour broking does indeed have a regressive element which hinders labour m arket functionality. An area for further research for TES employment would be to look at the impact of the amendments to the Labour Rela tions Act. Specifically focusing on the Constitutional Court ruling, which forces labour brokers to treat employees who have been employed for longer than three months as permanent employees.
- Full Text:
- Date Issued: 2020
- Authors: Haaketa, Bernadatte Tina
- Date: 2020
- Subjects: Veblen, Thorstein, 1857-1929 , Contracting out -- South Africa , Temporary employment -- South Africa , Industrial relations -- South Africa , Labor supply -- South Africa , Labor supply -- Effect of technological innovations on -- South Africa , Manpower policy -- South Africa , Labor market -- South Africa
- Language: English
- Type: text , Thesis , Masters , MCom
- Identifier: http://hdl.handle.net/10962/168446 , vital:41583
- Description: Labour markets ar ound the world have witnessed a great change in labour relations. The introduction of globa lisation, increased competition and technological advancements has caused business organisations to change their employment methods. While trying to survive and remain profitable, employers have adopted a new form of triangular employment relationship. Thi s form of employment relationship known as labour broking and which forms part of the Temporary Employment Services (TES) involves a relationship between the worker, labour agent (broker) and a client c ompany. Although it may seem like a good strategy for business organisations, the change in employment relationships has had negative effects and contributed to labour market dysfunctionalities . This has resulted in critics of labour broking calling or an end in labour broking and supporters of labour broking asking for better regulation of the industry. Labour markets are me When it comes to analysing labour broking and its impact on labour market functionality in South Africa. Scholars and analysts such as Budlender ( 2013 ) and Bhorat, Lil enstein, Oosthuizen , and Thornton ( 2016 ) have used the Neoclassical , New Institutional Economics and Marxist approach es. The current views on labour broking and the current schools of thought fail to look at the underlying behavioural aspect of labour brokers and the client c ompanies. Hence making it easy for labour brokers and their client companies to continue with their unscrupulous activities. However, this t hesis adapted the Veblenian Dichotomy framework which focuses on understanding the role of the evolutionary proce ss and the role of institutions in shaping economic behaviour. The Veblenian dichotomy shows that power plays an important role in how labour markets are run. Similarly, behaviour also influences the manner in which labour brokers and client companies trea t workers. And lastly the Veblenian dichotomy shows that in order for the industry to be run better there has to be change in the behaviour and cultu re of the labour brokers and client companies . This view allows for deeper analysis of the reasons for the flour ishing nature of labour broking and the rationale behind the behaviour of economic players and attempts to provide solutions on how labour brok ing can be correctly administered in South Africa. The Veblenian Dichotomy categorises institutions into t wo sets, namely the ceremonial institutions and instrumental institutions. Where Ceremonial institutions are said to be institutions that foster the interests of business such as profitability and earning of free income, even if there is no corresponding i ncrease in production. While Instrumental institutions, usually working through the influence of technology, address the interests of the common pers on and the labourer as well as business (Waller, 1982; Foster, 1981; Veblen, 1919). These two systems of va lues and institutions are antagonistic and the relative strength of one to the other determines economic outcomes and in whose interests the outcomes would be (Waller, 1982; Foster, 1981; Veblen, 1919). The Veblenian Dichotomy further looks at ceremonial encapsulation which occurs when ceremonial systems prevail over instrumental systems. Ceremonial encapsulation presents the hypothesis that the insti tutional structure will absorb new technology only to the extent that it can do so without disrupting the e xisting value structure (Waller, 1987; Bush, 1979.) The thesis use d various sources , such as working papers, public hearings, court cases, trade union submissions, integrated reports from companies, employee submissions and media publications on the debate about labour broking whether labour broking and applied the Interpretative Phenomenological Analysi s (IPA) research approach, in the process of data collection and analysis . The thesis further applied thematic analysis to derive themes that would be used to analyse the impact of labour broking on labour market functionality in South Africa. The emergent themes and subthemes were Exploitative lab our relations subthemes; job Insecurity, increased financial burden and no skills development. The second theme was; Competitive advantage and the subthemes were; i ncreased profits and organisational efficiency. The third theme was l abour market efficiency and the subthemes were. E mployment creation and labour market flexibility. And, the last theme was a mbiguous l abour regulation s with subthemes; n o freedom of association and a tool for circumventing labour regulations . Lastly, Tool’s (1994) criteria of j udgement for institutional adjustments was used to evaluate the emergent themes and to evaluate the impact of l abour broking on the overall welfare of individuals, which includes determining whether employees in the TES sector gain skills and improved stan dards of living. The findings of the research the TES sector is characterised by ceremonial values. Ceremonial values (as mentioned in section 3.3) are those values that are warranted by the ways of life that prescribe status and hierarchies and unpleasant distinctions to apply value and status on other people (Bush, 1987, 1988; Ayres, 1967). Thus changing the way in which labour brokers conduct themselves or handle labour broking activities would prove to be difficult . T he power that is mostly used in TES employment sectors is condign power. Condign power is explained as the form of power that is predominantly used in ceremonially encapsulated markets. And it involves making use of punishment or fear in order to get people to do something. This is because w orkers in the TES sector are forced to submit to conditions that they would not normally have submitted to if t hey did not have a fear of losing their jobs. This supports existing literature which shows that in the TES sector, TES employers use force and p ower in order to get the workers to do something, and this results in a master - servant relationship between the employer and the employee. Furthermore, the protests that erupt in the TES sector agree with Marxist theory which notes that the frustrations in the way workers are treated would result in a revolution of the working class against the employers. However, now, workers have not been able to overcome the employers and take over the industry. In addition to what current literature says, the research found that some managers make use of labour broking as a way of manifesting their exploitative characteristics on the labour market, thus creating information asymmetries in order to advance their own personal needs. Situations such as these reve al characteristics of opportunistic behaviour, which is perpetuated by the imperfect flow of information. This means th at the market is imperfect, and imperfect markets are characteristics of dysfunctional labour markets. The research also found that it i s the South African Constitution that protects labour brokers and client companies from accounting for the unfair treatm ent of workers. Labour brokers and client companies rely on the South African Constitution to defend them when it comes to banning labou r broking. This is because section 22 of the Constitution talks about the right of every individual to trade freely in S outh Africa (Kutumela, 2015). When institutional adjustments do not meet the requirements of the progressive criteria, it means they are regressive. Based on the data that was collected and the responses and remarks of the workers, trade unions, and trade union federations, it can be said that TES employment and labour broking hinders labour market functionality. Hence, it can be concluded that, due to the characteristics mentioned, labour broking does indeed have a regressive element which hinders labour m arket functionality. An area for further research for TES employment would be to look at the impact of the amendments to the Labour Rela tions Act. Specifically focusing on the Constitutional Court ruling, which forces labour brokers to treat employees who have been employed for longer than three months as permanent employees.
- Full Text:
- Date Issued: 2020
A vision based multirotor aircraft for use in the security industry
- Authors: Nelson, Benjamin David
- Date: 2020
- Subjects: Drone aircraft -- South Africa , Mechatronics -- Research
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46816 , vital:39664
- Description: This research consisted of developing a vision based multirotor aircraft that could be used in the security industry. A second-hand aircraft was purchased and modified. The aircraft made use of a Pixhawk flight controller and a Odroid XU4 companion computer, which resulted in the computer injecting commands into the flight controller. Robot Operating System was installed and used on the companion computer to integrate the vision system and the aircraft. The vision system was designed to help develop a landing system where the aircraft would land on an ArUco marker. The vision system also allowed the aircraft to detect and follow humans. A Software in the Loop (SITL) was run alongside Gazebo, allowing the developed landing system and the human detecting system to be simulated and tested. The developed landing system was implemented on the aircraft, where the developed landing system was tested and compared to the aircraft’s current GPS based landing system. The developed landing system obtained a better overall accuracy , while also taking longer to land the aircraft compared to the GPS based landing system. There were also numerous manual and autonomous test flights implemented on the aircraft.
- Full Text:
- Date Issued: 2020
- Authors: Nelson, Benjamin David
- Date: 2020
- Subjects: Drone aircraft -- South Africa , Mechatronics -- Research
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/46816 , vital:39664
- Description: This research consisted of developing a vision based multirotor aircraft that could be used in the security industry. A second-hand aircraft was purchased and modified. The aircraft made use of a Pixhawk flight controller and a Odroid XU4 companion computer, which resulted in the computer injecting commands into the flight controller. Robot Operating System was installed and used on the companion computer to integrate the vision system and the aircraft. The vision system was designed to help develop a landing system where the aircraft would land on an ArUco marker. The vision system also allowed the aircraft to detect and follow humans. A Software in the Loop (SITL) was run alongside Gazebo, allowing the developed landing system and the human detecting system to be simulated and tested. The developed landing system was implemented on the aircraft, where the developed landing system was tested and compared to the aircraft’s current GPS based landing system. The developed landing system obtained a better overall accuracy , while also taking longer to land the aircraft compared to the GPS based landing system. There were also numerous manual and autonomous test flights implemented on the aircraft.
- Full Text:
- Date Issued: 2020
Absent fathers: psychological and socio-economic implications for black children and directions for future research
- Magqamfana, Simnikiwe H, Bazana, Sandiso
- Authors: Magqamfana, Simnikiwe H , Bazana, Sandiso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163443 , vital:41038 , DOI: 10.1080/14330237.2020.1744299
- Description: This study investigated fathers’ absence influences on the self-perceptions of South African young adults. Informants were five black university students (two females, three males; age range 20 to 28 years). They responded to semi-structured face-to-face interviews on self-perceptions from having matured in the absence of their biological fathers. Thematic analysis of the data revealed that the informants consider the father-absence when they grapple with material well-being shortage. Participants had mixed perceptions about the psychosocial effects on them from father-absence, with some believing to be thriving despite a history of father-absence. Overall, the findings suggest a need for caution in pathologising young adults with a history of father-absence as necessarily deprived.
- Full Text:
- Date Issued: 2020
- Authors: Magqamfana, Simnikiwe H , Bazana, Sandiso
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/163443 , vital:41038 , DOI: 10.1080/14330237.2020.1744299
- Description: This study investigated fathers’ absence influences on the self-perceptions of South African young adults. Informants were five black university students (two females, three males; age range 20 to 28 years). They responded to semi-structured face-to-face interviews on self-perceptions from having matured in the absence of their biological fathers. Thematic analysis of the data revealed that the informants consider the father-absence when they grapple with material well-being shortage. Participants had mixed perceptions about the psychosocial effects on them from father-absence, with some believing to be thriving despite a history of father-absence. Overall, the findings suggest a need for caution in pathologising young adults with a history of father-absence as necessarily deprived.
- Full Text:
- Date Issued: 2020
Academic readiness of students for higher education: a case for academic support at Rhodes University
- Authors: Khoza, Lebogang Peter
- Date: 2020
- Subjects: College student development programs -- South Africa -- Makhanda , Dropouts -- Prevention , College students -- South Africa-- Makhanda -- Social conditions , School failure -- South Africa -- Makhanda , Academic achievement-- South Africa -- Makhanda , Student adjustment -- South Africa -- Makhanda , Counseling in higher education -- South Africa -- Makhanda , Student Integration Model , Conceptual Framework Model , Geometric Design of Student Persistence
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/147848 , vital:38678
- Description: The worrying existence of incidences of student retention, poor pass rates and an increase in repetition rates is a cause for concern for institutions of higher learning in South Africa. The problem of student retention is not new in our institutions of higher learning. Support structures, strategies, and policies need to be developed for different academic and social challenges that students face daily. This study explores the need for academic support at Rhodes University; it also explores the internal and external problems that students face, the perceptions and experiences of students on academic support available to them. The study implemented a narrative research approach implanted within a qualitative research framework. Data was collected through a questionnaire, and narrative interviews. Tinto’s Student Integration Model was used to analyse the data in this study and was supplemented by Louw’s conceptual framework model and Swail’s Geometric Design of Student Persistence. These three models position the student experience as the foundation for academic support programmes and development. The study argues that as long as effective and adequate academic support is lacking, students will continue to experience difficulties in completing their studies. The findings from the study reveal that at present, Rhodes University provides support to students who are in extended studies. However, this support system disadvantages many students, notably those not in the extended studies programme. As a result, such students are not supported through strategies and structures that extended studies students receive. Furthermore, the data generates internal and external problems that student face daily, as a result, the findings showed that there is a need for academic support at Rhodes. The study recommends that Rhodes University must establish an academic unit that will provide academic support to all students registered in the university.
- Full Text:
- Date Issued: 2020
- Authors: Khoza, Lebogang Peter
- Date: 2020
- Subjects: College student development programs -- South Africa -- Makhanda , Dropouts -- Prevention , College students -- South Africa-- Makhanda -- Social conditions , School failure -- South Africa -- Makhanda , Academic achievement-- South Africa -- Makhanda , Student adjustment -- South Africa -- Makhanda , Counseling in higher education -- South Africa -- Makhanda , Student Integration Model , Conceptual Framework Model , Geometric Design of Student Persistence
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: http://hdl.handle.net/10962/147848 , vital:38678
- Description: The worrying existence of incidences of student retention, poor pass rates and an increase in repetition rates is a cause for concern for institutions of higher learning in South Africa. The problem of student retention is not new in our institutions of higher learning. Support structures, strategies, and policies need to be developed for different academic and social challenges that students face daily. This study explores the need for academic support at Rhodes University; it also explores the internal and external problems that students face, the perceptions and experiences of students on academic support available to them. The study implemented a narrative research approach implanted within a qualitative research framework. Data was collected through a questionnaire, and narrative interviews. Tinto’s Student Integration Model was used to analyse the data in this study and was supplemented by Louw’s conceptual framework model and Swail’s Geometric Design of Student Persistence. These three models position the student experience as the foundation for academic support programmes and development. The study argues that as long as effective and adequate academic support is lacking, students will continue to experience difficulties in completing their studies. The findings from the study reveal that at present, Rhodes University provides support to students who are in extended studies. However, this support system disadvantages many students, notably those not in the extended studies programme. As a result, such students are not supported through strategies and structures that extended studies students receive. Furthermore, the data generates internal and external problems that student face daily, as a result, the findings showed that there is a need for academic support at Rhodes. The study recommends that Rhodes University must establish an academic unit that will provide academic support to all students registered in the university.
- Full Text:
- Date Issued: 2020
Acceptance of ambulatory blood pressure monitoring in a semi-rural population in South Africa:
- Chiwanza, Farisai, Irwin, Yoland, Dowse, Roslind
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
- Authors: Chiwanza, Farisai , Irwin, Yoland , Dowse, Roslind
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/157072 , vital:40084 , DOI: https://doi.org/10.4102/hsag.v25i0.1336
- Description: Ambulatory blood pressure monitoring is a valuable tool that helps in providing an insight into the diagnosis and management of hypertension; however, no evidence exists of its acceptance in the diverse South African population. We assessed the acceptance of an ambulatory blood pressure monitor in patients attending public sector primary health care (PHC) clinics. Five PHC clinics in the Makana subdistrict in the Eastern Cape.
- Full Text:
- Date Issued: 2020
Access to social grants information by the Balfour Village elderly population in Eastern Cape Province, South Africa
- Authors: Faku, Andile
- Date: 2020
- Subjects: Information services Information resources
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Library and Information Science)
- Identifier: http://hdl.handle.net/10353/18096 , vital:42231
- Description: This study sought to investigate the access to information about social grants by the elderly population of Balfour village in Raymond Mhlaba Local Municipality in SA’s Eastern Cape Province. A study on access to information is quite relevant in the knowledge-based economies. People act when they have information and similarly elderly people require information in order to access their grants. This study is quite relevant in the Library and Information Science field. The targeted population for the study were the elderly people of the Balfour village. The qualitative research approach was used in this study. The researcher selected a sample for the study using snowballsampling procedure. Both in-depth interviews and questionnaires were employed as methods of gathering data and thematic analysis of data was used. Results showed that there is a lack of information dissemination and access to information about social grants for elderly people living in Balfour. The study found out that elderly people in Balfour complained that, in most cases, they were not sure about the documents they were supposed to bring with them when they visited the South African Social Security Agency offices. This indicates the need for SASSA to train their staff members to be customer orientated and encourage staff to empower themselves with formal educational qualifications. In addition, the distance to and from SASSA offices is of great concern because elderly people spend significant amounts of money for travelling these distances. Therefore, there must be an office that is situated in a favourable distance to the elderly so that they do not struggle when they want to reach SASSA offices. Another option would be to avail a mobile office that may serve the area two or three times a week.
- Full Text:
- Date Issued: 2020
- Authors: Faku, Andile
- Date: 2020
- Subjects: Information services Information resources
- Language: English
- Type: Thesis , Masters , MSoc. Sci (Library and Information Science)
- Identifier: http://hdl.handle.net/10353/18096 , vital:42231
- Description: This study sought to investigate the access to information about social grants by the elderly population of Balfour village in Raymond Mhlaba Local Municipality in SA’s Eastern Cape Province. A study on access to information is quite relevant in the knowledge-based economies. People act when they have information and similarly elderly people require information in order to access their grants. This study is quite relevant in the Library and Information Science field. The targeted population for the study were the elderly people of the Balfour village. The qualitative research approach was used in this study. The researcher selected a sample for the study using snowballsampling procedure. Both in-depth interviews and questionnaires were employed as methods of gathering data and thematic analysis of data was used. Results showed that there is a lack of information dissemination and access to information about social grants for elderly people living in Balfour. The study found out that elderly people in Balfour complained that, in most cases, they were not sure about the documents they were supposed to bring with them when they visited the South African Social Security Agency offices. This indicates the need for SASSA to train their staff members to be customer orientated and encourage staff to empower themselves with formal educational qualifications. In addition, the distance to and from SASSA offices is of great concern because elderly people spend significant amounts of money for travelling these distances. Therefore, there must be an office that is situated in a favourable distance to the elderly so that they do not struggle when they want to reach SASSA offices. Another option would be to avail a mobile office that may serve the area two or three times a week.
- Full Text:
- Date Issued: 2020
Accessibility of agricultural information by smallholder farmers in Amatole District Municipality: Nexus between agricultural extension services and the library
- Authors: Sigigaba, Masimthembe
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18849 , vital:42870
- Description: Accessibility to relevant, accurate and timely information remains vital in farming. For farmers to improve their productivity they depend on access to pertinent agricultural information. Such information updated them about new agricultural technologies, climate change, new cultivars, access to market and access to financial assistance. These types of information help farmers in decision making regarding their farming. Agricultural extension officers remain a reliable source where farmers could obtain relevant agricultural information. Community libraries are also channels that could be used by agricultural extension officers to complement their work of providing farmers with information. Thus, the study sought to assess linkage between these two institutions to provide farmers with information. A positivism paradigm with quantitative research approach were adopted in the study. Smallholder farmers (169), agricultural extension officers (5) and librarians (15) were the unit of analysis. A semi-structured questionnaire was used for data collection and SPSS software for analysis. Findings revealed that, agricultural extension officers mostly utilise interpersonal channels that include demonstrations, group meetings and face-to-face interaction to provide farmers with information. Community libraries were found to be non-utilised by extension services and also by farmers. Farmers were of the perception that libraries are meant for educated people. It was also discovered that community libraries have information on agriculture that only targets learners who are taking agriculture in school as a subject. There was no existing linkage between agricultural extension services and community libraries working together to provide farmers with pertinent agricultural information that can help them improve productivity
- Full Text:
- Date Issued: 2020
- Authors: Sigigaba, Masimthembe
- Date: 2020
- Subjects: Farms, Small
- Language: English
- Type: Thesis , Masters , M Agric (Agric Extension)
- Identifier: http://hdl.handle.net/10353/18849 , vital:42870
- Description: Accessibility to relevant, accurate and timely information remains vital in farming. For farmers to improve their productivity they depend on access to pertinent agricultural information. Such information updated them about new agricultural technologies, climate change, new cultivars, access to market and access to financial assistance. These types of information help farmers in decision making regarding their farming. Agricultural extension officers remain a reliable source where farmers could obtain relevant agricultural information. Community libraries are also channels that could be used by agricultural extension officers to complement their work of providing farmers with information. Thus, the study sought to assess linkage between these two institutions to provide farmers with information. A positivism paradigm with quantitative research approach were adopted in the study. Smallholder farmers (169), agricultural extension officers (5) and librarians (15) were the unit of analysis. A semi-structured questionnaire was used for data collection and SPSS software for analysis. Findings revealed that, agricultural extension officers mostly utilise interpersonal channels that include demonstrations, group meetings and face-to-face interaction to provide farmers with information. Community libraries were found to be non-utilised by extension services and also by farmers. Farmers were of the perception that libraries are meant for educated people. It was also discovered that community libraries have information on agriculture that only targets learners who are taking agriculture in school as a subject. There was no existing linkage between agricultural extension services and community libraries working together to provide farmers with pertinent agricultural information that can help them improve productivity
- Full Text:
- Date Issued: 2020
Acetophenone substituted phthalocyanines and their graphene quantum dots conjugates as photosensitizers for photodynamic antimicrobial chemotherapy against Staphylococcus aureus
- Openda, Yolande I, Sen, Pinar, Managa, Muthumuni, Nyokong, Tebello
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
- Authors: Openda, Yolande I , Sen, Pinar , Managa, Muthumuni , Nyokong, Tebello
- Date: 2020
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186507 , vital:44506 , xlink:href="https://doi.org/10.1016/j.pdpdt.2019.101607"
- Description: This work reports on the synthesis and characterization of novel acetophenone substituted phthalocyanines along with the self-assembled nanoconjugates formed via π-π stacking interaction between the synthesized unmetalated (2), zinc (3) and indium (4) phthalocyanines and graphene quantum dots (GQDs) to form 2@GQDs, 3@GQDs and 4@GQDs. The complexes and conjugates exhibited high singlet oxygen ranging from 0.20 to 0.79 in DMSO for Pcs and nanoconjugates where in all cases, the indium complexes showed the highest singlet oxygen quantum yields. The photodynamic antimicrobial chemotherapy activity of both phthalocyanines and nanoconjugates were tested against Staphylococcus aureus. 4@GQDs was found to be highly effective causing a 9.68 log reduction of the bacteria at 10 μM (based on Pc) when compared to 3.77 log reduction of 3@GQDs.
- Full Text:
- Date Issued: 2020
Activity of diverse chalcones against several targets: statistical analysis of a high-throughput virtual screen of a custom chalcone library
- Authors: Sarron, Arthur F D
- Date: 2020
- Subjects: Acetophenone , Benzaldehyde , Ketones , Pyruvate kinase , Drug development , Aromatic compounds , Heat shock proteins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116028 , vital:34291
- Description: Chalcone family molecules are well known to have therapeutic proprieties (anti-inflammatory, anti-microbial or anti-cancer, etc). However the mechanism of action in some cases is not well known. A virtual library of this family of compounds was constructed using custom scripts, based on the aldol condensation, and this library was modified further to analogues by expansion of the α,β-unsaturated ketone linker. Acetophenone and benzaldehyde derivatives which are available and purchasable were used as a base to design the chalcone virtual library. 8063 chalcones were constructed and geometrically optimized with Gaussian 09. Their physicochemical characteristics linked to the Lipinski rules were analyzed with Knime and CDK. The entire library was after docked against several targets including HIV-1 integrase, MRSA pyruvate kinase, HSP90, COX-1, COX-2, ALR2, MAOA, MAOB, acetylcholinesterase, butyrylcholinesterase and PLA2. With the exception of MAOA, which does not have a crystal structure ligand, all dockings were validated by redocking the original ligand provided by the literature. These targets are known in the literature to be inhibited by chalcone-derivatives. However, specificity of the particular known chalcone inhibitors to the particular targets is not known. To this end the performance of the generated chalcone library against the list of targets was of interest. The binding energy of ligand-protein complexes was generally good across the library. Statistical analysis including principal component analysis and hierarchical clustering analysis were made in order to investigate for any physical/chemical characteristics which might explain what chalcone features affect the binding energy of the ligand-protein complexes. The spherical polar coordinates defining the orientation of the binding poses were also calculated and used in the statistical analysis. The statistical analysis has allowed us to hypothesize the importance of these radial distances and the polar angles of key atoms in the chalcones in binding to the pyruvate kinase crystal structure. This was validated by the docking of another small library of compound models in which the α,β-unsaturated ketone chain of the chalcone was replaced by incrementally longer conjugated chains. Further studies on the chalcones themselves reveal rotameric systems in both cis and trans-configurations (which may impact binding), and also studied was the effect of Topliss-based modification and its impact of binding to HSP90. Molecular dynamics confirmed good binding of identified chalcone hits.
- Full Text:
- Date Issued: 2020
- Authors: Sarron, Arthur F D
- Date: 2020
- Subjects: Acetophenone , Benzaldehyde , Ketones , Pyruvate kinase , Drug development , Aromatic compounds , Heat shock proteins
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/116028 , vital:34291
- Description: Chalcone family molecules are well known to have therapeutic proprieties (anti-inflammatory, anti-microbial or anti-cancer, etc). However the mechanism of action in some cases is not well known. A virtual library of this family of compounds was constructed using custom scripts, based on the aldol condensation, and this library was modified further to analogues by expansion of the α,β-unsaturated ketone linker. Acetophenone and benzaldehyde derivatives which are available and purchasable were used as a base to design the chalcone virtual library. 8063 chalcones were constructed and geometrically optimized with Gaussian 09. Their physicochemical characteristics linked to the Lipinski rules were analyzed with Knime and CDK. The entire library was after docked against several targets including HIV-1 integrase, MRSA pyruvate kinase, HSP90, COX-1, COX-2, ALR2, MAOA, MAOB, acetylcholinesterase, butyrylcholinesterase and PLA2. With the exception of MAOA, which does not have a crystal structure ligand, all dockings were validated by redocking the original ligand provided by the literature. These targets are known in the literature to be inhibited by chalcone-derivatives. However, specificity of the particular known chalcone inhibitors to the particular targets is not known. To this end the performance of the generated chalcone library against the list of targets was of interest. The binding energy of ligand-protein complexes was generally good across the library. Statistical analysis including principal component analysis and hierarchical clustering analysis were made in order to investigate for any physical/chemical characteristics which might explain what chalcone features affect the binding energy of the ligand-protein complexes. The spherical polar coordinates defining the orientation of the binding poses were also calculated and used in the statistical analysis. The statistical analysis has allowed us to hypothesize the importance of these radial distances and the polar angles of key atoms in the chalcones in binding to the pyruvate kinase crystal structure. This was validated by the docking of another small library of compound models in which the α,β-unsaturated ketone chain of the chalcone was replaced by incrementally longer conjugated chains. Further studies on the chalcones themselves reveal rotameric systems in both cis and trans-configurations (which may impact binding), and also studied was the effect of Topliss-based modification and its impact of binding to HSP90. Molecular dynamics confirmed good binding of identified chalcone hits.
- Full Text:
- Date Issued: 2020
Adaptive Neuro-Fuzzy Inference System modelling of surface topology in ultra-high precision diamond turning of rapidly solidified aluminium grade (RSA 443)
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
- Authors: Zvikomborero, Hweju
- Date: 2020
- Subjects: Mechatronics Surface roughness -- Measurement
- Language: English
- Type: Thesis , Masters , MEng
- Identifier: http://hdl.handle.net/10948/49441 , vital:41721
- Description: Surface roughness prediction is a crucial stage during product manufacturing since it acts as a quality indicator. This investigative research thesis presents an online surface roughness prediction, based on the Adaptive Neuro-Fuzzy Inference System (ANFIS) model during Ultra-High Precision Diamond Turning (UHPDT) of Rapidly Solidified Aluminium (RSA-443) using water and kerosene as coolants. Based on the Taguchi L9 orthogonal array, the cutting parameters (spindle speed, depth of cut and feed rate) are varied at three levels. Acoustic Emission (AE) signals are detected during the UHPDT process using a piezoelectric sensor. Spindle speed, depth of cut, feed rate, AE root mean square, prominent frequency and peak rate are considered as model inputs in this thesis. The experimental results reveal that a better surface finish is obtained using water coolant in comparison to kerosene coolant. Mean Absolute Percentage Error (MAPE) based comparison between ANFIS and Response Surface Method (RSM) is carried out. In this study, the ANFIS model has a prediction accuracy of 79.42% and 69.40% on water-based and kerosene-based results respectively. The RSM model yields higher prediction accuracies of 98.59% and 95.55% on water-based and kerosene-based results respectively.
- Full Text:
- Date Issued: 2020
Addo Elephant National Park 1900 – 1955: An Environmental History of the struggle between elephants and emerging commercial farmers in the Sundays River Valley
- Jones,Nicholas Austen Inskip
- Authors: Jones,Nicholas Austen Inskip
- Date: 2020
- Subjects: Wildlife conservation -- South Africa -- Addo National Park
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46922 , vital:39733
- Description: The research covers the first half of the 20th Century in the Sundays River Valley, and the relations between the elephants and the local farmers. The research includes some discussion of the implementation of new ideas to agriculture, irrigation, and colonial settlement with the interplay between the colonial farmers and the Administration. There is reference to the early politics surrounding nature conservation and the difficulties faced by farmers from wildlife and the difficulty wildlife face trying to co-exist alongside early intensive commercial agriculture.Included is the decision making process of the Colonial administration with reference to wildlife and agriculture relating to charismatic animal species.
- Full Text:
- Date Issued: 2020
- Authors: Jones,Nicholas Austen Inskip
- Date: 2020
- Subjects: Wildlife conservation -- South Africa -- Addo National Park
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/46922 , vital:39733
- Description: The research covers the first half of the 20th Century in the Sundays River Valley, and the relations between the elephants and the local farmers. The research includes some discussion of the implementation of new ideas to agriculture, irrigation, and colonial settlement with the interplay between the colonial farmers and the Administration. There is reference to the early politics surrounding nature conservation and the difficulties faced by farmers from wildlife and the difficulty wildlife face trying to co-exist alongside early intensive commercial agriculture.Included is the decision making process of the Colonial administration with reference to wildlife and agriculture relating to charismatic animal species.
- Full Text:
- Date Issued: 2020
Addressing flux suppression, radio frequency interference, and selection of optimal solution intervals during radio interferometric calibration
- Authors: Sob, Ulrich Armel Mbou
- Date: 2020
- Subjects: CubiCal (Software) , Radio -- Interference , Imaging systems in astronomy , Algorithms , Astronomical instruments -- Calibration , Astronomy -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147714 , vital:38663
- Description: The forthcoming Square Kilometre Array is expected to provide answers to some of the most intriguing questions about our Universe. However, as it is already noticeable from MeerKAT and other precursors, the amounts of data produced by these new instruments are significantly challenging to calibrate and image. Calibration of radio interferometric data is usually biased by incomplete sky models and radio frequency interference (RFI) resulting in calibration artefacts that limit the dynamic range and image fidelity of the resulting images. One of the most noticeable of these artefacts is the formation of spurious sources which causes suppression of real emissions. Fortunately, it has been shown that calibration algorithms employing heavy-tailed likelihood functions are less susceptible to this due to their robustness against outliers. Leveraging on recent developments in the field of complex optimisation, we implement a robust calibration algorithm using a Student’s t likelihood function and Wirtinger derivatives. The new algorithm, dubbed the robust solver, is incorporated as a subroutine into the newly released calibration software package CubiCal. We perform statistical analysis on the distribution of visibilities and provide an insight into the functioning of the robust solver and describe different scenarios where it will improve calibration. We use simulations to show that the robust solver effectively reduces the amount of flux suppressed from unmodelled sources both in direction independent and direction dependent calibration. Furthermore, the robust solver is shown to successfully mitigate the effects of low-level RFI when applied to a simulated and a real VLA dataset. Finally, we demonstrate that there are close links between the amount of flux suppressed from sources, the effects of the RFI and the employed solution interval during radio interferometric calibration. Hence, we investigate the effects of solution intervals and the different factors to consider in order to select adequate solution intervals. Furthermore, we propose a practical brute force method for selecting optimal solution intervals. The proposed method is successfully applied to a VLA dataset.
- Full Text:
- Date Issued: 2020
- Authors: Sob, Ulrich Armel Mbou
- Date: 2020
- Subjects: CubiCal (Software) , Radio -- Interference , Imaging systems in astronomy , Algorithms , Astronomical instruments -- Calibration , Astronomy -- Data processing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/147714 , vital:38663
- Description: The forthcoming Square Kilometre Array is expected to provide answers to some of the most intriguing questions about our Universe. However, as it is already noticeable from MeerKAT and other precursors, the amounts of data produced by these new instruments are significantly challenging to calibrate and image. Calibration of radio interferometric data is usually biased by incomplete sky models and radio frequency interference (RFI) resulting in calibration artefacts that limit the dynamic range and image fidelity of the resulting images. One of the most noticeable of these artefacts is the formation of spurious sources which causes suppression of real emissions. Fortunately, it has been shown that calibration algorithms employing heavy-tailed likelihood functions are less susceptible to this due to their robustness against outliers. Leveraging on recent developments in the field of complex optimisation, we implement a robust calibration algorithm using a Student’s t likelihood function and Wirtinger derivatives. The new algorithm, dubbed the robust solver, is incorporated as a subroutine into the newly released calibration software package CubiCal. We perform statistical analysis on the distribution of visibilities and provide an insight into the functioning of the robust solver and describe different scenarios where it will improve calibration. We use simulations to show that the robust solver effectively reduces the amount of flux suppressed from unmodelled sources both in direction independent and direction dependent calibration. Furthermore, the robust solver is shown to successfully mitigate the effects of low-level RFI when applied to a simulated and a real VLA dataset. Finally, we demonstrate that there are close links between the amount of flux suppressed from sources, the effects of the RFI and the employed solution interval during radio interferometric calibration. Hence, we investigate the effects of solution intervals and the different factors to consider in order to select adequate solution intervals. Furthermore, we propose a practical brute force method for selecting optimal solution intervals. The proposed method is successfully applied to a VLA dataset.
- Full Text:
- Date Issued: 2020
Adol-Safety: A Framework for Empowering Parents to be Aware of Social Network Threats Affecting Adolescents
- Mjoli, Phumelela, Shibeshi, Z
- Authors: Mjoli, Phumelela , Shibeshi, Z
- Date: 2020
- Subjects: Social networks Social media|
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/12016 , vital:39127
- Description: The use of social networks has grown so much that adolescents have become active members of various social networks such as Twitter, Facebook, and Instagram, etc. The gradual change in how people choose to communicate, socialize and share ideas today has influenced adolescents to an extent that they find themselves wanting to engage more on social networks than they really should due to peer pressure. Whenever a person joins social networks or browses the Internet, they by default are exposed and become vulnerable to many cyber threats. Cyber threats are driven by users that have negative intentions on the Internet or social networks. Adolescents are no exception to these cyber threats. The findings of this research reveal that threats such as cyberbullying, harassment, and online predators to name a few are often designed to abuse and affect adolescents). Therefore, this research aims to prevent such threats from prevailing by empowering parents to be aware of the threats that affect their adolescents in an online environment, which typically includes social networks. To achieve this, this research starts by investigating the cyber threats that affect adolescents and then explores ways that can be used to empower parents. A framework is developed to handle this. The framework includes strategies that parents can adopt and ways in which safety on social networks can be increased, as well as guidelines that can be followed in order to prevent cyber threats. The framework also aims to enhance a parent-child relationship that can help in preventing social network threats. Lastly, the framework is implemented as a knowledgesharing website that can be used by parents to receive and give an insight into social network threats that influence adolescents on social networks.
- Full Text:
- Date Issued: 2020
- Authors: Mjoli, Phumelela , Shibeshi, Z
- Date: 2020
- Subjects: Social networks Social media|
- Language: English
- Type: Thesis , Masters , MSc (Computer Science )
- Identifier: http://hdl.handle.net/10353/12016 , vital:39127
- Description: The use of social networks has grown so much that adolescents have become active members of various social networks such as Twitter, Facebook, and Instagram, etc. The gradual change in how people choose to communicate, socialize and share ideas today has influenced adolescents to an extent that they find themselves wanting to engage more on social networks than they really should due to peer pressure. Whenever a person joins social networks or browses the Internet, they by default are exposed and become vulnerable to many cyber threats. Cyber threats are driven by users that have negative intentions on the Internet or social networks. Adolescents are no exception to these cyber threats. The findings of this research reveal that threats such as cyberbullying, harassment, and online predators to name a few are often designed to abuse and affect adolescents). Therefore, this research aims to prevent such threats from prevailing by empowering parents to be aware of the threats that affect their adolescents in an online environment, which typically includes social networks. To achieve this, this research starts by investigating the cyber threats that affect adolescents and then explores ways that can be used to empower parents. A framework is developed to handle this. The framework includes strategies that parents can adopt and ways in which safety on social networks can be increased, as well as guidelines that can be followed in order to prevent cyber threats. The framework also aims to enhance a parent-child relationship that can help in preventing social network threats. Lastly, the framework is implemented as a knowledgesharing website that can be used by parents to receive and give an insight into social network threats that influence adolescents on social networks.
- Full Text:
- Date Issued: 2020
African Foreign Policies: Selecting signifiers to explain agency
- Authors: Bischoff, Paul, 1954-
- Date: 2020
- Subjects: Africa Foreign relations 1960- , Africa Politics and government 1960-
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/161716 , vital:40657 , ISBN 9780367348281 , https://www.routledge.com/African-Foreign-Policies-Selecting-Signifiers-to-Explain-Agency/Bischoff/p/book/9780367348281
- Description: This book explores, at a time when several powers have become serious players on the continent, aspects of African agency, past and present, by African writers on foreign policy, representative of geography, language and state size. In the past, African foreign policy has largely been considered within the context of reactions to the international or global 'external factor'. This ground-breaking book, however, looks at how foreign policy has been crafted and used in response not just to external, but also, mainly, domestic imperatives or (theoretical) signifiers. As such, it narrates individual and changing foreign policy orientations over time - and as far back as independence - with mainly African-based scholars who present their own constructs of what is a useful theoretical narrative regarding foreign policy on the continent - how theory is adapted to local circumstance or substituted for continentally based ontologies. The book therefore contends that the African experience carries valuable import for expanding general understandings of foreign policy in general. This book will be of key interest to scholars and students of Foreign Policy Analysis, Foreign Policy Studies, African International Relations/Politics/Studies, Diplomacy and more broadly to International Relations. , Introduction / Paul-Henri Bischoff -- What Next? Past and present African foreign policy concepts and practices / Paul-Henri Bischoff -- The African Union as a Foreign Policy Player: African Agency in International Cooperation / Tshepo Gwatiwa -- Unprincipled Pragmatism and Anti-Imperialist Impulses in an Interconnected World: The Zuma Presidency, 2009-2017 / Mzukisi Qobo -- Towards A Strategic Culture Approach to Understanding and Conceptualising Ethiopia's Foreign Policy Towards Israel and the Middle Eastern Arab Countries / Makonnen Tesfaye -- Nigeria's Foreign Policy and Intervention Behaviour in Africa: What Role for Agency? / Olumuyiwa Amao -- Zimbabwe and New Signifiers: Towards a cultural political economy of Foreign Policy Making / Mike Mavura -- Realist Conceptions of Kenya's Foreign Policy and Foreign Policy Behaviour: A Theoretical and Contextual Disposition / Korwa Gombe Adar and Mercy Kathambi Kaburu -- Addressing the Conceptual Void of African Small State Foreign Policy in Orthodox Theory: A Case Study of Botswana's Principled Pragmatism / Kabelo M. Mahupela -- Tunisia's Foreign Policy Towards France Before and After an Undemanding 'Revolution': A Theoretical Explanation of the An-Nahdha-led Interim Governments' Soft Policy / Ahmed Ali Salem -- Straddling Between Convergence and Divergence: A Constructivist's View of Malawi's Foreign Policy in Post-independence Africa / Eugenio Njoloma -- Strategies of a Small State Between Realism and Liberalism: Sixty Years of Guinea's Diplomacy and Foreign Policy (1958-2018) / Issaka K. Souaré -- Rethinking SADC's Collective Policymaking Processes on External Relations and Non-state Participation for Region-building / Cecilia Lwiindi Nedziwe -- Towards an Understanding of the Interplay Between Ghana's Foreign and Defence Policies / Kwesi Aning and Kwaku Danso -- Conclusion / Paul-Henri Bischoff
- Full Text:
- Date Issued: 2020
- Authors: Bischoff, Paul, 1954-
- Date: 2020
- Subjects: Africa Foreign relations 1960- , Africa Politics and government 1960-
- Language: English
- Type: text , book
- Identifier: http://hdl.handle.net/10962/161716 , vital:40657 , ISBN 9780367348281 , https://www.routledge.com/African-Foreign-Policies-Selecting-Signifiers-to-Explain-Agency/Bischoff/p/book/9780367348281
- Description: This book explores, at a time when several powers have become serious players on the continent, aspects of African agency, past and present, by African writers on foreign policy, representative of geography, language and state size. In the past, African foreign policy has largely been considered within the context of reactions to the international or global 'external factor'. This ground-breaking book, however, looks at how foreign policy has been crafted and used in response not just to external, but also, mainly, domestic imperatives or (theoretical) signifiers. As such, it narrates individual and changing foreign policy orientations over time - and as far back as independence - with mainly African-based scholars who present their own constructs of what is a useful theoretical narrative regarding foreign policy on the continent - how theory is adapted to local circumstance or substituted for continentally based ontologies. The book therefore contends that the African experience carries valuable import for expanding general understandings of foreign policy in general. This book will be of key interest to scholars and students of Foreign Policy Analysis, Foreign Policy Studies, African International Relations/Politics/Studies, Diplomacy and more broadly to International Relations. , Introduction / Paul-Henri Bischoff -- What Next? Past and present African foreign policy concepts and practices / Paul-Henri Bischoff -- The African Union as a Foreign Policy Player: African Agency in International Cooperation / Tshepo Gwatiwa -- Unprincipled Pragmatism and Anti-Imperialist Impulses in an Interconnected World: The Zuma Presidency, 2009-2017 / Mzukisi Qobo -- Towards A Strategic Culture Approach to Understanding and Conceptualising Ethiopia's Foreign Policy Towards Israel and the Middle Eastern Arab Countries / Makonnen Tesfaye -- Nigeria's Foreign Policy and Intervention Behaviour in Africa: What Role for Agency? / Olumuyiwa Amao -- Zimbabwe and New Signifiers: Towards a cultural political economy of Foreign Policy Making / Mike Mavura -- Realist Conceptions of Kenya's Foreign Policy and Foreign Policy Behaviour: A Theoretical and Contextual Disposition / Korwa Gombe Adar and Mercy Kathambi Kaburu -- Addressing the Conceptual Void of African Small State Foreign Policy in Orthodox Theory: A Case Study of Botswana's Principled Pragmatism / Kabelo M. Mahupela -- Tunisia's Foreign Policy Towards France Before and After an Undemanding 'Revolution': A Theoretical Explanation of the An-Nahdha-led Interim Governments' Soft Policy / Ahmed Ali Salem -- Straddling Between Convergence and Divergence: A Constructivist's View of Malawi's Foreign Policy in Post-independence Africa / Eugenio Njoloma -- Strategies of a Small State Between Realism and Liberalism: Sixty Years of Guinea's Diplomacy and Foreign Policy (1958-2018) / Issaka K. Souaré -- Rethinking SADC's Collective Policymaking Processes on External Relations and Non-state Participation for Region-building / Cecilia Lwiindi Nedziwe -- Towards an Understanding of the Interplay Between Ghana's Foreign and Defence Policies / Kwesi Aning and Kwaku Danso -- Conclusion / Paul-Henri Bischoff
- Full Text:
- Date Issued: 2020
Afromelampsalta, a new genus, a new species, and five new combinations of African cicadettine cicadas (Hemiptera: Cicadidae: Cicadettinae):
- Sanborn, Allen F, Villet, Martin H
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
- Authors: Sanborn, Allen F , Villet, Martin H
- Date: 2020
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/140680 , vital:37909
- Description: Afromelampsalta n. gen. is described for African species currently assigned to the genera Melampsalta Kolenati, 1857. Cicadetta Kolenati, 1857 and Pauropsalta Goding and Froggatt, 1904, and the new species Afromelampsalta luteofasciata n. gen., n. sp. is described. Afromelampsalta aethiopica (Distant, 1905) n. comb., A. cadisia (Walker, 1850) n. comb. and A. leucoptera (Germar, 1830) n. comb. are reassigned from Melampsalta to Afromelampsalta n. gen., A. limitata (Walker, 1852) n. comb. is transferred from Cicadetta Kolenati, 1857 and A. mimica (Distant ,1907) n. comb. is transferred from Pauropsalta Goding and Froggatt, 1904 to Afromelampsalta n. gen. Notes on the biology of the new species, a description of the exuvia of A. mimica n. comb., and a key to the species of African Cicadettini are provided.
- Full Text:
- Date Issued: 2020
Age is nothing but a number: Ben 10s, sugar mummies, and the South African gender order in the Daily Sun’s Facebook page
- Authors: Mlangeni, Ntombikayise Lina
- Date: 2020
- Subjects: May-December romances -- South Africa , Women in mass media , Men in mass media , Sex role in mass media , Masculinity in mass media , Feminism and mass media , Critical discourse analysis , Unemployment -- Social aspects -- South Africa , Daily Sun (South Africa) , Ben 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167077 , vital:41435
- Description: This thesis examines how meanings of masculinity and femininity are negotiated by South Africans on a social media platform linked to a popular local tabloid newspaper. In particular it explores conversations surrounding the Ben 10 phenomenon on the Daily Sun’s Facebook page. A Ben 10 is commonly understood as a young man who enters into a sexual relationship with an older woman, mostly in township settings, and readers engage vociferously over the meanings of such relationships. Using a constructivist understanding of gender, a thematic analysis is used to examine the Facebook comments on the Daily Sun’s most popular Ben 10 stories. South Africa’s constitution promotes the right to gender equality and freedom, which contributes to the normalisation of sex in public conversations and political debate. However, with high levels of unemployment and poverty in South Africa, the narrative of masculine success through work remains relatively unattainable. This tension between the narrative of male-bread winner through work and the reality of South Africa’s poverty and unemployment has been referred to as the crisis of masculinity. This thesis will argue that tabloids can play a strong political role by providing an alternative public sphere and that they can also assist their readers in coping with life in a democratic society by creating an imagined community of people sharing common experiences.
- Full Text:
- Date Issued: 2020
- Authors: Mlangeni, Ntombikayise Lina
- Date: 2020
- Subjects: May-December romances -- South Africa , Women in mass media , Men in mass media , Sex role in mass media , Masculinity in mass media , Feminism and mass media , Critical discourse analysis , Unemployment -- Social aspects -- South Africa , Daily Sun (South Africa) , Ben 10
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/167077 , vital:41435
- Description: This thesis examines how meanings of masculinity and femininity are negotiated by South Africans on a social media platform linked to a popular local tabloid newspaper. In particular it explores conversations surrounding the Ben 10 phenomenon on the Daily Sun’s Facebook page. A Ben 10 is commonly understood as a young man who enters into a sexual relationship with an older woman, mostly in township settings, and readers engage vociferously over the meanings of such relationships. Using a constructivist understanding of gender, a thematic analysis is used to examine the Facebook comments on the Daily Sun’s most popular Ben 10 stories. South Africa’s constitution promotes the right to gender equality and freedom, which contributes to the normalisation of sex in public conversations and political debate. However, with high levels of unemployment and poverty in South Africa, the narrative of masculine success through work remains relatively unattainable. This tension between the narrative of male-bread winner through work and the reality of South Africa’s poverty and unemployment has been referred to as the crisis of masculinity. This thesis will argue that tabloids can play a strong political role by providing an alternative public sphere and that they can also assist their readers in coping with life in a democratic society by creating an imagined community of people sharing common experiences.
- Full Text:
- Date Issued: 2020
Age of squid Loligo reynaudii d’Orbigny, 1845, and its possible use to test effectiveness of the closed season in protecting this resource
- Mwanangombe, Collette Habani
- Authors: Mwanangombe, Collette Habani
- Date: 2020
- Subjects: Loliginidae -- Spawning -- South Africa , Loliginidae -- Age determination , Loligo fisheries -- South Africa , Fishery management -- South Africa , Otoliths , Loliginidae – Eggs -- Incubation , Loliginidae – Growth , Fish stock assessment -- South Africa , Recruitment (Population biology) -- South Africa , Loligo reynaudii d’Orbigny
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144333 , vital:38336
- Description: This study presents age distributions representing populations of adult Loligo reynaudii, together with the results of spawning and commercial catches to assist in understanding the beneficial role of the closed season. The results were based on 791 samples collected during three closed seasons (November: 2003, 2004 and 2005) and out of closed season during April/May 2005. Age and predicted growth were examined by counting daily rings on statolith microstructures. The age in days after hatching ranged from 168 to 484 days (71-425 mm) in males and from 125 to 478 days (83-263 mm) in females. Average age at spawning was found to be 323 days in males and 316 days in females. Population estimates of growth rates were best described by a linear growth model which revealed that males grew faster than females in length as they grew older with growth rate ranging between 0.63 to 0.83 mm per day for males and between 0.22 to 0.32 mm per day for females. Back-calculated hatch dates and later egg-laying events for parental populations were determined. Results from back calculated egg laying dates (presented as percentage of frequency of all laying dates) indicated a highest total of 36%, 39% and 15% of eggs from all samples were laid during the closed season and nine days after the closed season during year 2003, 2004 and 2005 respectively. Monthly commercial total catches (2002-2005) showed an increase from November soon after the fishery resumed, up until the month of January. Daily catches were highest in November (up to 290 tonnes) relative to the daily catches observed in December and January in all the years. Results led to the conclusion that the closed season (25 October to 22 November) is beneficial for both the chokka resource and the fishery. This is because: a) there is time for enough spawning biomass to accumulate, which subsequently results in high catches (good fishery), in the current year, best immediately after season opens in November; b) there is a link in the results between egg laying dates in the period of closed season and immediately afterwards, and the magnitude of catches in last nine days of November.
- Full Text:
- Date Issued: 2020
- Authors: Mwanangombe, Collette Habani
- Date: 2020
- Subjects: Loliginidae -- Spawning -- South Africa , Loliginidae -- Age determination , Loligo fisheries -- South Africa , Fishery management -- South Africa , Otoliths , Loliginidae – Eggs -- Incubation , Loliginidae – Growth , Fish stock assessment -- South Africa , Recruitment (Population biology) -- South Africa , Loligo reynaudii d’Orbigny
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/144333 , vital:38336
- Description: This study presents age distributions representing populations of adult Loligo reynaudii, together with the results of spawning and commercial catches to assist in understanding the beneficial role of the closed season. The results were based on 791 samples collected during three closed seasons (November: 2003, 2004 and 2005) and out of closed season during April/May 2005. Age and predicted growth were examined by counting daily rings on statolith microstructures. The age in days after hatching ranged from 168 to 484 days (71-425 mm) in males and from 125 to 478 days (83-263 mm) in females. Average age at spawning was found to be 323 days in males and 316 days in females. Population estimates of growth rates were best described by a linear growth model which revealed that males grew faster than females in length as they grew older with growth rate ranging between 0.63 to 0.83 mm per day for males and between 0.22 to 0.32 mm per day for females. Back-calculated hatch dates and later egg-laying events for parental populations were determined. Results from back calculated egg laying dates (presented as percentage of frequency of all laying dates) indicated a highest total of 36%, 39% and 15% of eggs from all samples were laid during the closed season and nine days after the closed season during year 2003, 2004 and 2005 respectively. Monthly commercial total catches (2002-2005) showed an increase from November soon after the fishery resumed, up until the month of January. Daily catches were highest in November (up to 290 tonnes) relative to the daily catches observed in December and January in all the years. Results led to the conclusion that the closed season (25 October to 22 November) is beneficial for both the chokka resource and the fishery. This is because: a) there is time for enough spawning biomass to accumulate, which subsequently results in high catches (good fishery), in the current year, best immediately after season opens in November; b) there is a link in the results between egg laying dates in the period of closed season and immediately afterwards, and the magnitude of catches in last nine days of November.
- Full Text:
- Date Issued: 2020