Combined spectral and stimulated luminescence study of charge trapping and recombination processes in α-Al2O3:C
- Authors: Nyirenda, Angel Newton
- Date: 2018
- Subjects: Luminescence , Thermoluminescence , Luminescence spectroscopy , Carbon-doped aluminium oxide , Radioluminescence , Time-resolved X-ray excited optical luminescence
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62683 , vital:28235
- Description: The main objective of this project was to gain a deeper and better understanding of the luminescence processes in a-Al₂O₃:C, a highly-sensitive dosimetric material, using a combined spectral and stimulated luminescence study. The spectral studies concentrated on the emission spectra obtained using X-ray induced radioluminescence (XERL), thermoluminescence (XETL) and time-resolved X-ray excited optical luminescence (TR-XEOL) techniques. The stimulated luminescence studies were based on thermoluminescence (TL), optically stimulated luminescence (OSL) and phototransferred TL (PTTL) methods that were used in the study of the radiation-induced defects at high beta-doses and the deep traps, that is, traps with thermal depths beyond 500°C. The spectral and stimulated luminescence measurements were carried out using a high sensitivity luminescence spectrometer and a Ris0 TL/OSL Model DA-20 Reader, respectively. The XERL emission spectrum measured at room temperature shows seven gaussian peaks associated with F-centres (420 nm), F+-centres (334 nm), F2+-centres (559 nm), Stoke’s vibronic band of Cr3+ (671 nm), Cr3+ R-line emission (694 nm), anti-Stokes vibronic band of Cr3+ (710 nm) and an unidentified emission band (260-300 nm) which we associate with hole recombinations at a luminescence centre. The 694-nm R-line emission from Cr3+ impurity ions is most likely due to recombination of holes at Cr2+ during stimulated luminescence and as a result of an intracentre excitation of Cr3+ in photoluminescence (PL) due to photon absorption. The Cr3+ emission decreases in intensity, whereas the intensity of F-centre emission band is almost constant with repeated XERL measurements. Depending on the amount of X-ray irradiation dose, both holes and/or electrons may take place in the emission processes of peaks I (30-80°C), II (90-250°C) and III (250-320°C) during a TL readout, albeit, electron recombination is dominant regardless of dose. At higher doses, the XETL emission spectra indicate that the dominant band associated with TL peak III (250-320°C) in the material, shifts from F-centre to Cr3+. Using the deep-traps OSL, it has been confirmed that the main TL trap is also the main OSL trap whereas the TL traps lying in the temperature range of 400-550°C constitute the secondary OSL traps. There is evidence of strong retrapping at the main trap during optical stimulation of charges from the secondary OSL traps and the deep traps and that the retrapping occurs via the delocalized bands. At high-irradiation beta-doses, aggregate defect centres which significantly alter the TL and OSL properties, are induced in the material. The induced aggregate centres get completely obliterated by heating a sample to 700°C. The radiation-induced defects cause the main TL peak to shift towards higher temperatures, increase its FWHM, reduce its maximum intensity and cause an underestimation of both the activation energy and order of kinetics of the peak. On the other hand, the OSL response of the material is enhanced following a high-irradiation dose. During sample storage in the dark at ambient temperature, charges do migrate from the deep traps (donors) to the main and intermediate traps (acceptors) and that the major donor traps during this charge transfer phenomenon lie between 500-600°C.
- Full Text:
- Authors: Nyirenda, Angel Newton
- Date: 2018
- Subjects: Luminescence , Thermoluminescence , Luminescence spectroscopy , Carbon-doped aluminium oxide , Radioluminescence , Time-resolved X-ray excited optical luminescence
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62683 , vital:28235
- Description: The main objective of this project was to gain a deeper and better understanding of the luminescence processes in a-Al₂O₃:C, a highly-sensitive dosimetric material, using a combined spectral and stimulated luminescence study. The spectral studies concentrated on the emission spectra obtained using X-ray induced radioluminescence (XERL), thermoluminescence (XETL) and time-resolved X-ray excited optical luminescence (TR-XEOL) techniques. The stimulated luminescence studies were based on thermoluminescence (TL), optically stimulated luminescence (OSL) and phototransferred TL (PTTL) methods that were used in the study of the radiation-induced defects at high beta-doses and the deep traps, that is, traps with thermal depths beyond 500°C. The spectral and stimulated luminescence measurements were carried out using a high sensitivity luminescence spectrometer and a Ris0 TL/OSL Model DA-20 Reader, respectively. The XERL emission spectrum measured at room temperature shows seven gaussian peaks associated with F-centres (420 nm), F+-centres (334 nm), F2+-centres (559 nm), Stoke’s vibronic band of Cr3+ (671 nm), Cr3+ R-line emission (694 nm), anti-Stokes vibronic band of Cr3+ (710 nm) and an unidentified emission band (260-300 nm) which we associate with hole recombinations at a luminescence centre. The 694-nm R-line emission from Cr3+ impurity ions is most likely due to recombination of holes at Cr2+ during stimulated luminescence and as a result of an intracentre excitation of Cr3+ in photoluminescence (PL) due to photon absorption. The Cr3+ emission decreases in intensity, whereas the intensity of F-centre emission band is almost constant with repeated XERL measurements. Depending on the amount of X-ray irradiation dose, both holes and/or electrons may take place in the emission processes of peaks I (30-80°C), II (90-250°C) and III (250-320°C) during a TL readout, albeit, electron recombination is dominant regardless of dose. At higher doses, the XETL emission spectra indicate that the dominant band associated with TL peak III (250-320°C) in the material, shifts from F-centre to Cr3+. Using the deep-traps OSL, it has been confirmed that the main TL trap is also the main OSL trap whereas the TL traps lying in the temperature range of 400-550°C constitute the secondary OSL traps. There is evidence of strong retrapping at the main trap during optical stimulation of charges from the secondary OSL traps and the deep traps and that the retrapping occurs via the delocalized bands. At high-irradiation beta-doses, aggregate defect centres which significantly alter the TL and OSL properties, are induced in the material. The induced aggregate centres get completely obliterated by heating a sample to 700°C. The radiation-induced defects cause the main TL peak to shift towards higher temperatures, increase its FWHM, reduce its maximum intensity and cause an underestimation of both the activation energy and order of kinetics of the peak. On the other hand, the OSL response of the material is enhanced following a high-irradiation dose. During sample storage in the dark at ambient temperature, charges do migrate from the deep traps (donors) to the main and intermediate traps (acceptors) and that the major donor traps during this charge transfer phenomenon lie between 500-600°C.
- Full Text:
Decentralization and quality assurance in the Ugandan primary education sector
- Authors: Abu-Baker, Mutaaya Sirajee
- Date: 2018
- Subjects: Schools -- Decentralization -- Uganda , Education, Primary -- Uganda , Educational change -- Uganda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57390 , vital:26897
- Description: The study presented in this thesis is a case study analysis of decentralization and quality assurance in a decentralized set up of the Ugandan Primary Schooling. The research looked at how the monitoring and evaluation informed the policy formulation process to regulate quality assurance in a decentralized governance of primary education. The Study was positioned in the critical realist paradigm, interpretive in orientation and used both coding and thematic techniques to understand the teachers’, SMC members’, and officers’ (at district and ministry levels) experiences and perceptions of quality assurance in a decentralized set up. Data was gathered using interviews, document analysis and observation methods. The findings indicated that the study was affected by eleven themes: Management System and Leadership, Human Resource Management, Finance Administration and Management, Parenting and Nutrition, Politics, Motivation, Social Structures and Patterns, Legislative Process and Policies, Infrastructure Development and Management, Community Involvement in Education and Curriculum and Professionalism. The monitoring and evaluation system had a framework in which it operates, though there was no quality assurance policy to guide the provision of quality education. The study finally indicated that there are more threats in a decentralized set up that put Quality in danger. Secondly, there was absence of supervision/inspection in schools as there was no evidence to prove this due to absence of reports. However, document analysis indicated visits of officers to schools. Records management was a problem to schools. Decentralization was adopted at different levels by different countries to address specific problems identified in view of service delivery. Finally, though monitoring and evaluation results informed the policy and decision makers, there was no quality assurance policy to guide the provision of quality education in institutions.
- Full Text:
- Authors: Abu-Baker, Mutaaya Sirajee
- Date: 2018
- Subjects: Schools -- Decentralization -- Uganda , Education, Primary -- Uganda , Educational change -- Uganda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/57390 , vital:26897
- Description: The study presented in this thesis is a case study analysis of decentralization and quality assurance in a decentralized set up of the Ugandan Primary Schooling. The research looked at how the monitoring and evaluation informed the policy formulation process to regulate quality assurance in a decentralized governance of primary education. The Study was positioned in the critical realist paradigm, interpretive in orientation and used both coding and thematic techniques to understand the teachers’, SMC members’, and officers’ (at district and ministry levels) experiences and perceptions of quality assurance in a decentralized set up. Data was gathered using interviews, document analysis and observation methods. The findings indicated that the study was affected by eleven themes: Management System and Leadership, Human Resource Management, Finance Administration and Management, Parenting and Nutrition, Politics, Motivation, Social Structures and Patterns, Legislative Process and Policies, Infrastructure Development and Management, Community Involvement in Education and Curriculum and Professionalism. The monitoring and evaluation system had a framework in which it operates, though there was no quality assurance policy to guide the provision of quality education. The study finally indicated that there are more threats in a decentralized set up that put Quality in danger. Secondly, there was absence of supervision/inspection in schools as there was no evidence to prove this due to absence of reports. However, document analysis indicated visits of officers to schools. Records management was a problem to schools. Decentralization was adopted at different levels by different countries to address specific problems identified in view of service delivery. Finally, though monitoring and evaluation results informed the policy and decision makers, there was no quality assurance policy to guide the provision of quality education in institutions.
- Full Text:
Development and validation of a health literacy measure for limited literacy public sector patients in South Africa
- Authors: Marimwe, Chipiwa
- Date: 2018
- Subjects: Health literacy -- South Africa , Patient education -- South Africa , Communication in medicine -- South Africa , Health literacy -- Social aspects -- South Africa , Poor -- Medical care -- South Africa , Analysis of variance , Multidimensional Screener of Functional Health Literacy (MSFHL)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62661 , vital:28227
- Description: The growing complexity of healthcare demands greater patient involvement and skills to navigate this complex system. It has therefore become increasingly important to identify individuals with inadequate health literacy, by using efficient, short and reliable measures for doing so. Most research on the development and validation of health literacy tests has been conducted in high-income countries, with very little reported from low-and middle-income countries (LMICs). Existing health literacy measures have come under scrutiny for their lack of cultural sensitivity, bias towards certain population groups and failure to acknowledge health literacy as a multidimensional concept. These measures usually have limited application in LMICs due to the significantly different structuring of healthcare systems, they overlook the extreme discrepancies in educational levels, and rely too heavily on the ability to read health information. No health literacy data for South Africa are available, and only a few health literacy-based research papers have been published in this country. The aim of the study was to develop and validate a health literacy measure that is contextually and culturally appropriate to measure health literacy in limited literacy public sector patients in South Africa. An Item Bank of 30 questions was developed with the input of a diverse expert consultant panel, and included skills-based and self-reported questions which ensured cultural, contextual and educational level appropriateness. The Information and Support for Health Actions Questionnaire (ISHA-Q) is a health literacy measure developed to assess health literacy for LMICs which includes 14 core scales. These were useful in ensuring coverage of a range of health literacy constructs within the Item Bank. The 30 questions were then allocated to one of three health literacy domains: Procedural knowledge, Factual knowledge and Access to healthcare, health services and social support. Ethical approval for the study was obtained. The questions were translated into isiXhosa and underwent pilot testing. Following pilot testing, 120 isiXhosa first-language speakers, at least 18 years old, who attended public sector facilities and had a maximum 12 years of education were recruited from a primary healthcare clinic in Grahamstown. An interpreter was trained and he participated in all interviews. A questionnaire was used to collect data on the 30-question Item Bank. The Multidimensional Screener of Functional Health Literacy (MSFHL) was used as the primary comparator.The second phase of the study involved the refinement of the 30 questions in the Item Bank, which involved a multi-stage process. Data were analysed statistically using t-test, correlations, chi-square and ANOVA tests at a 5% level of significance, in order to identify problematic questions. Item Response Theory was used to ascertain difficulty and discriminatory ability of the questions. Each question was further subjected to in-depth interrogation by a panel of healthcare professionals to ensure that questions were supported by the conceptual framework and the definitions of health literacy adopted for this study. The number of questions was reduced from 30 to 12, and formed the new Health Literacy Test - Limited Literacy (HELT-LL). To validate the HELT-LL, 210 patients with the same inclusion criteria as previously noted, were recruited from four primary healthcare clinics in the Eastern Cape Province. Individual interviews were conducted with the assistance of the interpreter to collect sociodemographic data as well as data from the HELT-LL, the primary comparator (MSFHL), and a secondary comparator which was a South African modified version of the Newest Vital Sign (NVS-SA). The HELT-LL was re-administered to 40 patients in a follow-up interview two weeks later. The HELT-LL categorised only 17.6% of the patients as having adequate health literacy, just over a third with inadequate health literacy, and the majority with marginal health literacy. Questions in the cognitively demanding Procedural knowledge domain were the most poorly answered, with a mean score of 48.6±24.9%. Patients had great difficulty performing the basic numeric tasks in this domain. The overall mean score for the HELT-LL was 52.8±18.4%, compared with the more cognitively demanding NVS-SA with a mean of 28.6±21.1%, and clearly illustrated the impact of the strategy to include in the HELT-LL a variety of questions with differing cognitive load. The MSFHL, which is based on demographic characteristics and perceived difficulties with reading and writing, had an overall mean score of 44.4±26.2%. Demographic characteristics including age, education and English literacy, were found to be good predictors of limited health literacy, with significant correlations being found between these variables and the mean HELT-LL score. An acceptable value for Cronbach’s alpha, excellent test-retest reliability and excellent concurrent validity show that the HELT-LL is a valid and reliable measure of health literacy in our target population. As there is a paucity of health literacy research emanating from developing countries, this study presents a significant contribution to literature. It is the first study to report the development and validation of a health literacy measure to address the dearth of available health literacy measures applicable for South Africa. If implemented for use in clinical settings and for research purposes, it could provide valuable South African health literacy data which could inform the development of interventions focusing on improving health literacy and health outcomes.
- Full Text:
- Authors: Marimwe, Chipiwa
- Date: 2018
- Subjects: Health literacy -- South Africa , Patient education -- South Africa , Communication in medicine -- South Africa , Health literacy -- Social aspects -- South Africa , Poor -- Medical care -- South Africa , Analysis of variance , Multidimensional Screener of Functional Health Literacy (MSFHL)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62661 , vital:28227
- Description: The growing complexity of healthcare demands greater patient involvement and skills to navigate this complex system. It has therefore become increasingly important to identify individuals with inadequate health literacy, by using efficient, short and reliable measures for doing so. Most research on the development and validation of health literacy tests has been conducted in high-income countries, with very little reported from low-and middle-income countries (LMICs). Existing health literacy measures have come under scrutiny for their lack of cultural sensitivity, bias towards certain population groups and failure to acknowledge health literacy as a multidimensional concept. These measures usually have limited application in LMICs due to the significantly different structuring of healthcare systems, they overlook the extreme discrepancies in educational levels, and rely too heavily on the ability to read health information. No health literacy data for South Africa are available, and only a few health literacy-based research papers have been published in this country. The aim of the study was to develop and validate a health literacy measure that is contextually and culturally appropriate to measure health literacy in limited literacy public sector patients in South Africa. An Item Bank of 30 questions was developed with the input of a diverse expert consultant panel, and included skills-based and self-reported questions which ensured cultural, contextual and educational level appropriateness. The Information and Support for Health Actions Questionnaire (ISHA-Q) is a health literacy measure developed to assess health literacy for LMICs which includes 14 core scales. These were useful in ensuring coverage of a range of health literacy constructs within the Item Bank. The 30 questions were then allocated to one of three health literacy domains: Procedural knowledge, Factual knowledge and Access to healthcare, health services and social support. Ethical approval for the study was obtained. The questions were translated into isiXhosa and underwent pilot testing. Following pilot testing, 120 isiXhosa first-language speakers, at least 18 years old, who attended public sector facilities and had a maximum 12 years of education were recruited from a primary healthcare clinic in Grahamstown. An interpreter was trained and he participated in all interviews. A questionnaire was used to collect data on the 30-question Item Bank. The Multidimensional Screener of Functional Health Literacy (MSFHL) was used as the primary comparator.The second phase of the study involved the refinement of the 30 questions in the Item Bank, which involved a multi-stage process. Data were analysed statistically using t-test, correlations, chi-square and ANOVA tests at a 5% level of significance, in order to identify problematic questions. Item Response Theory was used to ascertain difficulty and discriminatory ability of the questions. Each question was further subjected to in-depth interrogation by a panel of healthcare professionals to ensure that questions were supported by the conceptual framework and the definitions of health literacy adopted for this study. The number of questions was reduced from 30 to 12, and formed the new Health Literacy Test - Limited Literacy (HELT-LL). To validate the HELT-LL, 210 patients with the same inclusion criteria as previously noted, were recruited from four primary healthcare clinics in the Eastern Cape Province. Individual interviews were conducted with the assistance of the interpreter to collect sociodemographic data as well as data from the HELT-LL, the primary comparator (MSFHL), and a secondary comparator which was a South African modified version of the Newest Vital Sign (NVS-SA). The HELT-LL was re-administered to 40 patients in a follow-up interview two weeks later. The HELT-LL categorised only 17.6% of the patients as having adequate health literacy, just over a third with inadequate health literacy, and the majority with marginal health literacy. Questions in the cognitively demanding Procedural knowledge domain were the most poorly answered, with a mean score of 48.6±24.9%. Patients had great difficulty performing the basic numeric tasks in this domain. The overall mean score for the HELT-LL was 52.8±18.4%, compared with the more cognitively demanding NVS-SA with a mean of 28.6±21.1%, and clearly illustrated the impact of the strategy to include in the HELT-LL a variety of questions with differing cognitive load. The MSFHL, which is based on demographic characteristics and perceived difficulties with reading and writing, had an overall mean score of 44.4±26.2%. Demographic characteristics including age, education and English literacy, were found to be good predictors of limited health literacy, with significant correlations being found between these variables and the mean HELT-LL score. An acceptable value for Cronbach’s alpha, excellent test-retest reliability and excellent concurrent validity show that the HELT-LL is a valid and reliable measure of health literacy in our target population. As there is a paucity of health literacy research emanating from developing countries, this study presents a significant contribution to literature. It is the first study to report the development and validation of a health literacy measure to address the dearth of available health literacy measures applicable for South Africa. If implemented for use in clinical settings and for research purposes, it could provide valuable South African health literacy data which could inform the development of interventions focusing on improving health literacy and health outcomes.
- Full Text:
Elevated CO2 determines cell damage and nitrogen allocation in barley subjected to aphid herbivory
- Authors: Gallagher, Sean
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64337 , vital:28535
- Description: Expected release date-May 2019
- Full Text:
- Authors: Gallagher, Sean
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64337 , vital:28535
- Description: Expected release date-May 2019
- Full Text:
Energy use patterns and trends: the impact of energy policy in South African low-income households
- Israel-Akinbo, Sylvia Olawumi
- Authors: Israel-Akinbo, Sylvia Olawumi
- Date: 2018
- Subjects: Energy policy -- Social aspects -- South Africa , Energy security -- South Africa , Households -- Economic aspects -- South Africa , Poor -- Energy assistance -- South Africa , Poor -- South Africa , University of Cape Town. National Income Dynamics Study , Free Basic Electricity Policy (South Africa) , Income and Expenditure Survey (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62264 , vital:28148
- Description: Energy poverty is a growing concern especially amongst low-income populations in developing countries. The transition to modern energy carriers is associated with welfare improvement and it is considered as an important developmental goal to achieve, in order to eradicate energy poverty. As such, the South African government has made energy poverty an issue of policy focus. Literature abounds with different measures of energy poverty; energy programmes and policies are also aimed at improving the welfare of the low-income households in terms of basic services such as electricity. As a point of entry into this study, this thesis explored energy use patterns and trends in low-income South African households. The research objectives addressed in the study included investigating the extent of energy poverty through a multidimensional energy poverty index, examining the extent to which the 'energy ladder' and 'energy stacking' models explains energy transition patterns and to examining whether the Free Basic Electricity Policy has impacted on energy choices and energy poverty. In order to contribute to energy poverty and energy policy discussion in South Africa, this study has investigated the dimensions of energy poverty amongst low-income South African households from these three different perspectives (objectives). A positivist approach, by using a quantitative method was used to underpin the study. The study utilised secondary data, which were from the National Income Dynamics Survey and Income and Expenditure Survey. The former was used for the analysis of the multidimensional energy poverty index and energy transition patterns whilst the latter was used for the analysis of the impact of the Free Basic Electricity Policy. The four waves of the National Income Dynamics Survey, with 2008 as the base year and the 2010/2011 version of the Income and Expenditure Survey were used whilst the data were processed through the quantitative software package, STATA version 12. The data were then analysed using the multidimensional energy poverty framework by Nussbaumer et al. (2011) and econometric models, which best fit the objectives. The result of the panel analysis, which assesses the multidimensional energy poverty for low-income households in South Africa showed that low-income households in both urban and rural areas are in a moderate state of energy poverty but different levels. However, the cross-sectional analysis revealed that the percentage of low-income households that are energy poor is reducing for the rural households but increasing for their urban counterparts from 2008 to 2014. The panel and cross-sectional results of the contribution of the energy dimensions in multidimensional energy poverty shows that the low-income households are especially energy poor in terms of heating fuel. The findings from the econometric estimates partly confirmed an energy ladder behaviour for the energy choice for cooking. An energy stacking behaviour was confirmed for the low- income households for these energy services - heating and lighting. Moreover, it was found that with respect to cooking and heating, low-income households living in a modern dwelling, having a small household size and residing in an urban area are less likely to use transitional or traditional energy carriers but most likely to use modern energy carriers. In addition, low-income households are more likely to use modern energy carriers for their cooking and heating in 2010, 2012 and 2014 than in 2008. For lighting energy service, low- income households living in a modern dwelling in an urban settlement are most likely to use modern energy carriers for lighting and less likely to use transitional energy carriers or candles. Only in 2014 were low-income households more likely to use modern energy carriers for lighting than in 2008. The results further showed that modern energy carriers have the highest probability of being preferred for lighting followed by cooking and lastly heating. Also emerging from the findings are that more urban low-income households are receiving the Free Basic Electricity (FBE) grant than their counterparts in the rural areas. The probability of low-income households owning entertainment/education appliance and food preserving appliance is positively influenced by access to Free Basic Electricity. The low- income households living in an urban settlement and in a modern type of dwelling supported this result. However, household size does not seems to support this result should it grow larger.
- Full Text:
- Authors: Israel-Akinbo, Sylvia Olawumi
- Date: 2018
- Subjects: Energy policy -- Social aspects -- South Africa , Energy security -- South Africa , Households -- Economic aspects -- South Africa , Poor -- Energy assistance -- South Africa , Poor -- South Africa , University of Cape Town. National Income Dynamics Study , Free Basic Electricity Policy (South Africa) , Income and Expenditure Survey (South Africa)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62264 , vital:28148
- Description: Energy poverty is a growing concern especially amongst low-income populations in developing countries. The transition to modern energy carriers is associated with welfare improvement and it is considered as an important developmental goal to achieve, in order to eradicate energy poverty. As such, the South African government has made energy poverty an issue of policy focus. Literature abounds with different measures of energy poverty; energy programmes and policies are also aimed at improving the welfare of the low-income households in terms of basic services such as electricity. As a point of entry into this study, this thesis explored energy use patterns and trends in low-income South African households. The research objectives addressed in the study included investigating the extent of energy poverty through a multidimensional energy poverty index, examining the extent to which the 'energy ladder' and 'energy stacking' models explains energy transition patterns and to examining whether the Free Basic Electricity Policy has impacted on energy choices and energy poverty. In order to contribute to energy poverty and energy policy discussion in South Africa, this study has investigated the dimensions of energy poverty amongst low-income South African households from these three different perspectives (objectives). A positivist approach, by using a quantitative method was used to underpin the study. The study utilised secondary data, which were from the National Income Dynamics Survey and Income and Expenditure Survey. The former was used for the analysis of the multidimensional energy poverty index and energy transition patterns whilst the latter was used for the analysis of the impact of the Free Basic Electricity Policy. The four waves of the National Income Dynamics Survey, with 2008 as the base year and the 2010/2011 version of the Income and Expenditure Survey were used whilst the data were processed through the quantitative software package, STATA version 12. The data were then analysed using the multidimensional energy poverty framework by Nussbaumer et al. (2011) and econometric models, which best fit the objectives. The result of the panel analysis, which assesses the multidimensional energy poverty for low-income households in South Africa showed that low-income households in both urban and rural areas are in a moderate state of energy poverty but different levels. However, the cross-sectional analysis revealed that the percentage of low-income households that are energy poor is reducing for the rural households but increasing for their urban counterparts from 2008 to 2014. The panel and cross-sectional results of the contribution of the energy dimensions in multidimensional energy poverty shows that the low-income households are especially energy poor in terms of heating fuel. The findings from the econometric estimates partly confirmed an energy ladder behaviour for the energy choice for cooking. An energy stacking behaviour was confirmed for the low- income households for these energy services - heating and lighting. Moreover, it was found that with respect to cooking and heating, low-income households living in a modern dwelling, having a small household size and residing in an urban area are less likely to use transitional or traditional energy carriers but most likely to use modern energy carriers. In addition, low-income households are more likely to use modern energy carriers for their cooking and heating in 2010, 2012 and 2014 than in 2008. For lighting energy service, low- income households living in a modern dwelling in an urban settlement are most likely to use modern energy carriers for lighting and less likely to use transitional energy carriers or candles. Only in 2014 were low-income households more likely to use modern energy carriers for lighting than in 2008. The results further showed that modern energy carriers have the highest probability of being preferred for lighting followed by cooking and lastly heating. Also emerging from the findings are that more urban low-income households are receiving the Free Basic Electricity (FBE) grant than their counterparts in the rural areas. The probability of low-income households owning entertainment/education appliance and food preserving appliance is positively influenced by access to Free Basic Electricity. The low- income households living in an urban settlement and in a modern type of dwelling supported this result. However, household size does not seems to support this result should it grow larger.
- Full Text:
Factors that shape learner achievement in socially disadvantaged and rural contexts: a social realist study in two rural senior secondary schools in Omusati region, Namibia
- Authors: Shilongo, Erica
- Date: 2018
- Subjects: Academic achievement Namibia Omusati , High school students Namibia Omusati Social conditions , Rural schools Namibia Omusati , Education, Rural Namibia Omusati , Social realism
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62240 , vital:28146
- Description: Learners’ performance and the reasons for either achievement or failure in school has lo ng been a topic of debate. In early research on academic achievement, theorists, educators, biologists and psychologists traditionally focused on the learners from socially disadvantaged family backgrounds who underachieve. Much of the debate internationally centred on whether learner academic achievement / underachievement is a product of hereditary traits or the social context. In particular, arguments for and against whether the reasons for the achievement / underachievement of children from socially disadvantaged families are genetic or the social context in which they find themselves continue unabated. Such explanations do not provide insight into why it is that despite familial (genetic) and social circumstances (social disadvantage), some children succeed and/or are able to act outside expectations of failure. Little research has focused on those in the same or similar contexts who are achieving academic success despite their limiting circumstances and the reasons for their success. This study used a social realist lens to investigate the factors that shape the academic achievement of 12 learners in two rural senior secondary schools in Omusati region, Namibia. All 12 learners are from low socioeconomic family backgrounds. The data was collected through survey, interviews with learners, parents and teachers, field notes and document analysis. The main finding of the study show that contrary to research that portrayed learners’ achievement as determined either by heredity or social contexts, the 12 learners constantly used their agentic possibilities to navigate constraining structural and cultural conditions at regional, familial and school levels to achieve academic success. Their agency was shaped by the socioeconomic conditions in their lives, namely, socioeconomic deprivation; large extended families in rural households, lack of amenities and utilities in their families, participation in household chores, experience of family tragedies and of changes when they were young.
- Full Text:
- Authors: Shilongo, Erica
- Date: 2018
- Subjects: Academic achievement Namibia Omusati , High school students Namibia Omusati Social conditions , Rural schools Namibia Omusati , Education, Rural Namibia Omusati , Social realism
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62240 , vital:28146
- Description: Learners’ performance and the reasons for either achievement or failure in school has lo ng been a topic of debate. In early research on academic achievement, theorists, educators, biologists and psychologists traditionally focused on the learners from socially disadvantaged family backgrounds who underachieve. Much of the debate internationally centred on whether learner academic achievement / underachievement is a product of hereditary traits or the social context. In particular, arguments for and against whether the reasons for the achievement / underachievement of children from socially disadvantaged families are genetic or the social context in which they find themselves continue unabated. Such explanations do not provide insight into why it is that despite familial (genetic) and social circumstances (social disadvantage), some children succeed and/or are able to act outside expectations of failure. Little research has focused on those in the same or similar contexts who are achieving academic success despite their limiting circumstances and the reasons for their success. This study used a social realist lens to investigate the factors that shape the academic achievement of 12 learners in two rural senior secondary schools in Omusati region, Namibia. All 12 learners are from low socioeconomic family backgrounds. The data was collected through survey, interviews with learners, parents and teachers, field notes and document analysis. The main finding of the study show that contrary to research that portrayed learners’ achievement as determined either by heredity or social contexts, the 12 learners constantly used their agentic possibilities to navigate constraining structural and cultural conditions at regional, familial and school levels to achieve academic success. Their agency was shaped by the socioeconomic conditions in their lives, namely, socioeconomic deprivation; large extended families in rural households, lack of amenities and utilities in their families, participation in household chores, experience of family tragedies and of changes when they were young.
- Full Text:
Graphene quantum dots and their metallophthalocyanines nanoconjugates as novel photoluminescent nanosensors
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
- Authors: Achadu, Ojodomo John
- Date: 2018
- Subjects: Quantum dots , Graphene , Phthalocyanines , Nanoconjugates , Novel photoluminescent nanosensors , Metallophthalocyanines
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60719 , vital:27821
- Description: The fabrication and application of graphene quantum dots (GQDs)-based photoluminescent probes for the detection of analytes is presented. GQDs were functionalized with complexes such as metallophthalocyanines (MPcs), metal nanoparticles (Au@Ag NPs), 2,2,6,6-tetramethyl(piperidin-1-yl)oxyl (TEMPO), maleimide and thymine for the sensing of target analytes such as ascorbic acid (AA), biothiols (cysteine, homocysteine and glutathione) and mercury ion (Hg²+). The design strategy and approach was based on the quenching of the fluorescence of the GQDs upon functionalization with the above-mentioned complexes, which could be restored in the presence of the target analytes (due to their specific interaction affinity with the complexes). For the detection of AA, GQDs were covalently and/or non-covalently conjugated to TEMPO-bearing complexes to form GQDs-4A-TEMPO and GQDs-TEMPO-MPc systems with nanomolar limits of detection. For the detection of biothiols, Au@Ag NPs and maleimide-bearing complexes (MPc), which have specific affinity to interact with biothiols, were deployed. Hg²+ detection involved the use of GQDs and/or MPcs with thiol and thymine groups, respectively. In addition, a smart sensing platform was designed for the dual detection of biothiols and Hg²+ using supramolecular hybrid of polyethyleneimine functionalized-GQDs and MPc-Au@Ag conjugate. The probe could detect, in a sequential manner, Hg²+ and biothiols with high sensitivity. Results obtained from the LODs of the probes showed that GQDs sensing performances could be enhanced in the presence of MPcs. The probes designed in this work were successfully deployed in the assays of the target analytes in real samples and the recoveries obtained confirmed the analytical applicability of the probes.
- Full Text:
Integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho: a new institutional economics approach
- Authors: Rantlo, Montoeli Ashby
- Date: 2018
- Subjects: Farms, Small Lesotho , Mohair Lesotho , Institutional economics , Transaction costs , Informal sector (Economics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62275 , vital:28149
- Description: Agriculture continues to be a strategic sector in the development of most low-income countries like Lesotho where small-scale farming is the dominant livelihood activity that provides income and employment to the people. Smallholder farmers' integration into the commercial agricultural markets is a crucial element for economic development and has become a part of development strategies for developing countries and the objectives of international development institutions. The integration of the smallholders into these markets is dependent upon a number of factors including formal and informal institutions. Factors like population growth and demographic changes, technological change and introduction of new commodities, development of infrastructure and market institutions, development of the nonfarm sector and broader economy, rising labour opportunity costs, and macroeconomic, trade and sectoral policies affecting prices and other driving forces determine market participation. In addition, development of input and output markets, institutions like property rights and land tenure, market regulations, cultural and social factors affecting consumption preferences, production and market opportunities and constraints, agro-climatic conditions, and production and market related risks are other factors that affect the commercialisation process. On the other hand, factors like smallholder resource endowments including land and other natural capital, labour, physical capital, and human capital among others are household specific and considered internal determinants of market participation. Nevertheless, the decision to participate in agricultural markets lies with the individual farming household. Under the New Institutional Economics (NIE), this decision is influenced by institutional factors such as risk and preferences, factors which affect household production and the level of costs associated with market transactions. These market transactions are commonly referred to as transaction costs. The study focused on investigating the institutions that limit the integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho. The documentation and evaluation of the institutional structure of the mohair industry is performed whereby the institutional factors influencing participation of small-scale mohair farmers in formal, informal and illegal markets in Lesotho and factors contributing to transaction costs associated with the integration of small-scale farmers into the commercial mohair sector are investigated. Therefore, the investigation will help to address the institutional problems hindering the development of an effective marketing structure for the commercialisation of small-scale mohair producers in Lesotho. The results of the study show that the small-scale mohair farmers that use the formal markets are integrated into the commercial agricultural economy and these farmers' integration into the mainstream economy is influenced by access to government support in the form of shearing sheds, transport subsidies and advisory services. They also have access to market information, marketing infrastructure, knowledge of grades and standards and secure property rights. Other factors that helped their integration into the commercial economy is their contractual agreements with mohair buyers, path dependent based decision making as well as the collective approach to mohair farming. The small-scale mohair farmers using the informal markets do not receive the advantages received by the famers in the formal markets. These small-scale mohair farmers are not integrated into the commercial markets and their only option is the informal markets and their participation in these markets is enhanced by their marketing arrangements with the informal traders, culture influenced decisions, social capital and prompt payments. Despite integration into the commercial agricultural economy, small-scale farmers that use formal markets face the challenges of power imbalances, mistrust and conflicts which may affect this integration into the commercial markets if left unchecked. The study concludes that in the face of institutional challenges, the small-scale mohair farmers using the formal markets are integrated into the commercial agricultural economy and there is potential for improvement of their integration as well as the integration of the small-scale mohair farmers that use the informal markets if institutional challenges are addressed.
- Full Text:
- Authors: Rantlo, Montoeli Ashby
- Date: 2018
- Subjects: Farms, Small Lesotho , Mohair Lesotho , Institutional economics , Transaction costs , Informal sector (Economics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62275 , vital:28149
- Description: Agriculture continues to be a strategic sector in the development of most low-income countries like Lesotho where small-scale farming is the dominant livelihood activity that provides income and employment to the people. Smallholder farmers' integration into the commercial agricultural markets is a crucial element for economic development and has become a part of development strategies for developing countries and the objectives of international development institutions. The integration of the smallholders into these markets is dependent upon a number of factors including formal and informal institutions. Factors like population growth and demographic changes, technological change and introduction of new commodities, development of infrastructure and market institutions, development of the nonfarm sector and broader economy, rising labour opportunity costs, and macroeconomic, trade and sectoral policies affecting prices and other driving forces determine market participation. In addition, development of input and output markets, institutions like property rights and land tenure, market regulations, cultural and social factors affecting consumption preferences, production and market opportunities and constraints, agro-climatic conditions, and production and market related risks are other factors that affect the commercialisation process. On the other hand, factors like smallholder resource endowments including land and other natural capital, labour, physical capital, and human capital among others are household specific and considered internal determinants of market participation. Nevertheless, the decision to participate in agricultural markets lies with the individual farming household. Under the New Institutional Economics (NIE), this decision is influenced by institutional factors such as risk and preferences, factors which affect household production and the level of costs associated with market transactions. These market transactions are commonly referred to as transaction costs. The study focused on investigating the institutions that limit the integration of small-scale mohair farmers into the commercial agricultural economy in Lesotho. The documentation and evaluation of the institutional structure of the mohair industry is performed whereby the institutional factors influencing participation of small-scale mohair farmers in formal, informal and illegal markets in Lesotho and factors contributing to transaction costs associated with the integration of small-scale farmers into the commercial mohair sector are investigated. Therefore, the investigation will help to address the institutional problems hindering the development of an effective marketing structure for the commercialisation of small-scale mohair producers in Lesotho. The results of the study show that the small-scale mohair farmers that use the formal markets are integrated into the commercial agricultural economy and these farmers' integration into the mainstream economy is influenced by access to government support in the form of shearing sheds, transport subsidies and advisory services. They also have access to market information, marketing infrastructure, knowledge of grades and standards and secure property rights. Other factors that helped their integration into the commercial economy is their contractual agreements with mohair buyers, path dependent based decision making as well as the collective approach to mohair farming. The small-scale mohair farmers using the informal markets do not receive the advantages received by the famers in the formal markets. These small-scale mohair farmers are not integrated into the commercial markets and their only option is the informal markets and their participation in these markets is enhanced by their marketing arrangements with the informal traders, culture influenced decisions, social capital and prompt payments. Despite integration into the commercial agricultural economy, small-scale farmers that use formal markets face the challenges of power imbalances, mistrust and conflicts which may affect this integration into the commercial markets if left unchecked. The study concludes that in the face of institutional challenges, the small-scale mohair farmers using the formal markets are integrated into the commercial agricultural economy and there is potential for improvement of their integration as well as the integration of the small-scale mohair farmers that use the informal markets if institutional challenges are addressed.
- Full Text:
Investigating combinations of feature extraction and classification for improved image-based multimodal biometric systems at the feature level
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
- Authors: Brown, Dane
- Date: 2018
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63470 , vital:28414
- Description: Multimodal biometrics has become a popular means of overcoming the limitations of unimodal biometric systems. However, the rich information particular to the feature level is of a complex nature and leveraging its potential without overfitting a classifier is not well studied. This research investigates feature-classifier combinations on the fingerprint, face, palmprint, and iris modalities to effectively fuse their feature vectors for a complementary result. The effects of different feature-classifier combinations are thus isolated to identify novel or improved algorithms. A new face segmentation algorithm is shown to increase consistency in nominal and extreme scenarios. Moreover, two novel feature extraction techniques demonstrate better adaptation to dynamic lighting conditions, while reducing feature dimensionality to the benefit of classifiers. A comprehensive set of unimodal experiments are carried out to evaluate both verification and identification performance on a variety of datasets using four classifiers, namely Eigen, Fisher, Local Binary Pattern Histogram and linear Support Vector Machine on various feature extraction methods. The recognition performance of the proposed algorithms are shown to outperform the vast majority of related studies, when using the same dataset under the same test conditions. In the unimodal comparisons presented, the proposed approaches outperform existing systems even when given a handicap such as fewer training samples or data with a greater number of classes. A separate comprehensive set of experiments on feature fusion show that combining modality data provides a substantial increase in accuracy, with only a few exceptions that occur when differences in the image data quality of two modalities are substantial. However, when two poor quality datasets are fused, noticeable gains in recognition performance are realized when using the novel feature extraction approach. Finally, feature-fusion guidelines are proposed to provide the necessary insight to leverage the rich information effectively when fusing multiple biometric modalities at the feature level. These guidelines serve as the foundation to better understand and construct biometric systems that are effective in a variety of applications.
- Full Text:
Key considerations for novel aptamer generation and aptasensor platform design: a case study on human α-thrombin and histamine as sensor targets
- Authors: Ho, Lance St John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63534 , vital:28432
- Description: Expected release date-April 2020
- Full Text:
- Authors: Ho, Lance St John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63534 , vital:28432
- Description: Expected release date-April 2020
- Full Text:
Knowledge and knowers in Educational Leadership and Management (ELM) Master’s Programmes in South Africa
- Authors: Kajee, Farhana Amod
- Date: 2018
- Subjects: Educational leadership -- South Africa , Teachers -- Training of -- South Africa , Education, Higher -- South Africa , Master of education degree -- South Africa , Knowledge, Theory of , Educational sociology -- South Africa , Education, Higher -- Aims and objectives -- South Africa , Legitimation Code Theory (LCT)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60698 , vital:27819
- Description: This dissertation examines the knowledge and knower practices in the Master’s in Educational Leadership and Management (ELM) coursework programmes at South African public universities. This study was prompted by my growing awareness of problems and tensions in the field of ELM generally, and at the level of programme design of the M Ed degree in particular. Many of these had been identified by a national audit of coursework M Eds in ELM (CHE, 2010), and this study sought to find a way of theorising these with a view to improving both course design and teaching. To this end I employed Maton’s Legitimation Code Theory (LCT) which enables critical engagement with knowledge and knowers in programmes, how they are positioned, and how this positioning may be problematic. Hence my first research question sought to discover and critique what counted as knowledge in these programmes and why, while the second asked how knowers were positioned, and why this had come to be the case. LCT has its roots in the work of Bernstein and Maton, whose preoccupation with curriculum was/is driven by a sense of social justice: if we can understand how and why the curriculum is organised and presented in a particular way, it becomes possible to re-imagine teaching and learning, making it accessible to a broader, more inclusive body of learners. The study also drew on critical realism as an underlabourer. This philosophy provided a nuanced understanding of ontology, encouraging and enabling me, as researcher, to unearth causal mechanisms driving the status quo. Only seven South African universities currently offer the coursework option of a Master’s degree in ELM, compared to thirteen when the audit was conducted in 2010. Six of the universities agreed to take part in the study. Data was gathered through content analysis of the six course outlines and interviews with individual co-ordinators or academics centrally involved in the programmes. Through the development of a translation device I was able to establishing that a knower code was dominant in the programmes. Using this point as my departure, I interrogated the knowledge practices and found that different types of knowledge were being privileged across the programmes, with some having a practical/professional leaning and others a more academic/theoretical orientation. The resultant tension does, I argue, restrict knowledge building and helps to account for the fact that the field is generally considered to be under-theorised. The fact all of these programme are registered with the same national qualifications authority, ostensibly following the same national guidelines for Master’s degrees is worrying. The study attempts to find underlying, historically significant reasons for this unevenness. An analysis of the programmes revealed a leaning towards supportive pedagogical approaches. While all programmes promote a cultivated gaze their purposes are not always the same. While a hegemonic practices potential for opening counts as knowledge, cultivated gaze can enable transformation, it can also encourage that can impede real change and empowerment. The study has the up much needed debate on what is meant by a Master’s in ELM, what and what kinds of knower are envisaged.
- Full Text:
- Authors: Kajee, Farhana Amod
- Date: 2018
- Subjects: Educational leadership -- South Africa , Teachers -- Training of -- South Africa , Education, Higher -- South Africa , Master of education degree -- South Africa , Knowledge, Theory of , Educational sociology -- South Africa , Education, Higher -- Aims and objectives -- South Africa , Legitimation Code Theory (LCT)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60698 , vital:27819
- Description: This dissertation examines the knowledge and knower practices in the Master’s in Educational Leadership and Management (ELM) coursework programmes at South African public universities. This study was prompted by my growing awareness of problems and tensions in the field of ELM generally, and at the level of programme design of the M Ed degree in particular. Many of these had been identified by a national audit of coursework M Eds in ELM (CHE, 2010), and this study sought to find a way of theorising these with a view to improving both course design and teaching. To this end I employed Maton’s Legitimation Code Theory (LCT) which enables critical engagement with knowledge and knowers in programmes, how they are positioned, and how this positioning may be problematic. Hence my first research question sought to discover and critique what counted as knowledge in these programmes and why, while the second asked how knowers were positioned, and why this had come to be the case. LCT has its roots in the work of Bernstein and Maton, whose preoccupation with curriculum was/is driven by a sense of social justice: if we can understand how and why the curriculum is organised and presented in a particular way, it becomes possible to re-imagine teaching and learning, making it accessible to a broader, more inclusive body of learners. The study also drew on critical realism as an underlabourer. This philosophy provided a nuanced understanding of ontology, encouraging and enabling me, as researcher, to unearth causal mechanisms driving the status quo. Only seven South African universities currently offer the coursework option of a Master’s degree in ELM, compared to thirteen when the audit was conducted in 2010. Six of the universities agreed to take part in the study. Data was gathered through content analysis of the six course outlines and interviews with individual co-ordinators or academics centrally involved in the programmes. Through the development of a translation device I was able to establishing that a knower code was dominant in the programmes. Using this point as my departure, I interrogated the knowledge practices and found that different types of knowledge were being privileged across the programmes, with some having a practical/professional leaning and others a more academic/theoretical orientation. The resultant tension does, I argue, restrict knowledge building and helps to account for the fact that the field is generally considered to be under-theorised. The fact all of these programme are registered with the same national qualifications authority, ostensibly following the same national guidelines for Master’s degrees is worrying. The study attempts to find underlying, historically significant reasons for this unevenness. An analysis of the programmes revealed a leaning towards supportive pedagogical approaches. While all programmes promote a cultivated gaze their purposes are not always the same. While a hegemonic practices potential for opening counts as knowledge, cultivated gaze can enable transformation, it can also encourage that can impede real change and empowerment. The study has the up much needed debate on what is meant by a Master’s in ELM, what and what kinds of knower are envisaged.
- Full Text:
Knowledge practices and student access and success in General Chemistry at a Large South African University
- Authors: Mtombeni, Thabile Nokuthula
- Date: 2018
- Subjects: Chemistry -- Study and teaching (Higher) -- South Africa , Knowledge management , Education, Higher -- Curricula -- South Africa , Critical realism , Social integration -- South Africa , Educational equalization -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62873 , vital:28305
- Description: This dissertation reports on an investigation into the structuring principles of the General Chemistry curriculum at a Large South African University (LSAU). Student learning in the introductory modules of General Chemistry is critical for access to a range of fields since it is a requisite course for a variety of degree programmes. However, there is ample evidence that success in this subject remains a major challenge, particularly for black students. My quest in this study was to explore how the curriculum could enable greater epistemic access and thus include more students in science programmes at the LSAU. I investigated the organising principles underlying the curriculum practices of the General Chemistry module and explored the effects of the curriculum structure on student learning. Theoretically and conceptually, the study was underpinned by a social realist approach which holds that knowledge is stratified, differentiated, and has real emergent properties, powers and effects. The research question that I attempted to answer in this study was: How do knowledge practices privileged in the General Chemistry curriculum at the LSAU enable or constrain student learning? I adopted an intensive research design approach to conduct a qualitative case study using social realism and LCT as theoretical and analytical lenses. I used empirical data such as curriculum documents and interviews with lecturers to uncover the underlying generative mechanisms of the curriculum. I adopted a multi-layered data analysis process to make visible the underlying organising principles informing knowledge practices in the curriculum so that I could explain their potential effects on student learning. The first level of analysis explored the context of the curriculum and associated knowledge practices, and examined the pedagogic discourse evident in the curriculum. The second level of analysis revealed the inner logic structuring the curriculum and the associated knowledge practices. I used Maton’s Legitimation Code Theory (LCT): Specialisation to identify the specialisation codes, gazes and insights generated by the curriculum. For the third level of analysis, LCT: Semantics was used to generate the semantic profiles of learning activities to determine the extent to which the curriculum structure made cumulative learning possible. From the findings, it is evident that the verticality of knowledge in General Chemistry points to a recontextualising principle that prescribes the selection and arrangement of knowledge, and the special relationship of actors and discourses. As a result, the strong framing of the instructional discourse of General Chemistry curriculum structure is likely to constrain epistemological access for large numbers of students. In order to improve epistemological access to the field, weaker framing of the instructional discourse in introductory science is necessary. Weaker framing of the General Chemistry curriculum would require, in particular, changes to pacing, and that the evaluative criteria are made explicit. This is especially necessary when certain abstract and complex curricular content is taught, especially in the first semester. The findings also indicate that the nature of the organising principles in the curriculum are significant for improving epistemological access to knowledge. In terms of LCT: Specialisation, the General Chemistry curriculum generated a knowledge code and downplayed differences among social categories of students, thus positioning all equally in relation to the knowledge and practices of the field. Therefore, the structuring of the curriculum emphasises and legitimates students who have attained specialist knowledge without considering the nature of the new student coming into the educational setting. Simply, what is privileged is both the object of study (theoretical knowledge) and how it is studied (procedural knowledge). This finding is in line with the general outcomes of Chemistry education. In addition, the purist insight generated by the curriculum further attests to where the emphasis is placed in the curriculum. I argue that the lack of social relations in the curriculum poses a challenge for the holistic development of students as science knowers. The analysis of the learning activities shows rapid code shifts that indicate changes in cognitive demand and modes of thinking required of students. I argue that signposting the changes in complexity of knowledge and in the mode of thinking required could make learning, and thus epistemological access, more possible. Given the imperative of access to powerful knowledge, I contend that the curriculum should be reshaped to enable epistemological access for more students.
- Full Text:
- Authors: Mtombeni, Thabile Nokuthula
- Date: 2018
- Subjects: Chemistry -- Study and teaching (Higher) -- South Africa , Knowledge management , Education, Higher -- Curricula -- South Africa , Critical realism , Social integration -- South Africa , Educational equalization -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62873 , vital:28305
- Description: This dissertation reports on an investigation into the structuring principles of the General Chemistry curriculum at a Large South African University (LSAU). Student learning in the introductory modules of General Chemistry is critical for access to a range of fields since it is a requisite course for a variety of degree programmes. However, there is ample evidence that success in this subject remains a major challenge, particularly for black students. My quest in this study was to explore how the curriculum could enable greater epistemic access and thus include more students in science programmes at the LSAU. I investigated the organising principles underlying the curriculum practices of the General Chemistry module and explored the effects of the curriculum structure on student learning. Theoretically and conceptually, the study was underpinned by a social realist approach which holds that knowledge is stratified, differentiated, and has real emergent properties, powers and effects. The research question that I attempted to answer in this study was: How do knowledge practices privileged in the General Chemistry curriculum at the LSAU enable or constrain student learning? I adopted an intensive research design approach to conduct a qualitative case study using social realism and LCT as theoretical and analytical lenses. I used empirical data such as curriculum documents and interviews with lecturers to uncover the underlying generative mechanisms of the curriculum. I adopted a multi-layered data analysis process to make visible the underlying organising principles informing knowledge practices in the curriculum so that I could explain their potential effects on student learning. The first level of analysis explored the context of the curriculum and associated knowledge practices, and examined the pedagogic discourse evident in the curriculum. The second level of analysis revealed the inner logic structuring the curriculum and the associated knowledge practices. I used Maton’s Legitimation Code Theory (LCT): Specialisation to identify the specialisation codes, gazes and insights generated by the curriculum. For the third level of analysis, LCT: Semantics was used to generate the semantic profiles of learning activities to determine the extent to which the curriculum structure made cumulative learning possible. From the findings, it is evident that the verticality of knowledge in General Chemistry points to a recontextualising principle that prescribes the selection and arrangement of knowledge, and the special relationship of actors and discourses. As a result, the strong framing of the instructional discourse of General Chemistry curriculum structure is likely to constrain epistemological access for large numbers of students. In order to improve epistemological access to the field, weaker framing of the instructional discourse in introductory science is necessary. Weaker framing of the General Chemistry curriculum would require, in particular, changes to pacing, and that the evaluative criteria are made explicit. This is especially necessary when certain abstract and complex curricular content is taught, especially in the first semester. The findings also indicate that the nature of the organising principles in the curriculum are significant for improving epistemological access to knowledge. In terms of LCT: Specialisation, the General Chemistry curriculum generated a knowledge code and downplayed differences among social categories of students, thus positioning all equally in relation to the knowledge and practices of the field. Therefore, the structuring of the curriculum emphasises and legitimates students who have attained specialist knowledge without considering the nature of the new student coming into the educational setting. Simply, what is privileged is both the object of study (theoretical knowledge) and how it is studied (procedural knowledge). This finding is in line with the general outcomes of Chemistry education. In addition, the purist insight generated by the curriculum further attests to where the emphasis is placed in the curriculum. I argue that the lack of social relations in the curriculum poses a challenge for the holistic development of students as science knowers. The analysis of the learning activities shows rapid code shifts that indicate changes in cognitive demand and modes of thinking required of students. I argue that signposting the changes in complexity of knowledge and in the mode of thinking required could make learning, and thus epistemological access, more possible. Given the imperative of access to powerful knowledge, I contend that the curriculum should be reshaped to enable epistemological access for more students.
- Full Text:
Left-invariant optimal control problems of the Engel group: classification, stability, and integration
- Authors: McLean, Catherine Eve
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62949 , vital:28323 , http://doi.org/10.21504/10962/62949
- Description: Expected release date-April 2020
- Full Text:
- Authors: McLean, Catherine Eve
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62949 , vital:28323 , http://doi.org/10.21504/10962/62949
- Description: Expected release date-April 2020
- Full Text:
Long-term analysis of ionospheric response during geomagnetic storms in mid, low and equatorial latitudes
- Matamba, Tshimangadzo Merline
- Authors: Matamba, Tshimangadzo Merline
- Date: 2018
- Subjects: Ionospheric storms , Coronal mass ejections , Corotating interaction regions , Solar flares , Global Positioning System , Ionospheric critical frequencies , Equatorial Ionization Anomaly (EIA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63991 , vital:28517
- Description: Understanding changes in the ionosphere is important for High Frequency (HF) communications and navigation systems. Ionospheric storms are the disturbances in the Earth’s upper atmosphere due to solar activities such as Coronal Mass Ejections (CMEs), Corotating interaction Regions (CIRs) and solar flares. This thesis reports for the first time on an investigation of ionospheric response to great geomagnetic storms (Disturbance storm time, Dst ≤ −350 nT) that occurred during solar cycle 23. The storm periods analysed were 29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004. Global Navigation Satellite System (GNSS), Total Electron Content (TEC) and ionosonde critical frequency of F2 layer (foF2) data over northern hemisphere (European sector) and southern hemisphere (African sector) mid-latitudes were used to study the ionospheric responses within 15E° - 40°E longitude and ±31°- ±46° geomagnetic latitude. Mid-latitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low latitude changes especially the expansion of Equatorial Ionization Anomaly (EIA) also known as the dayside ionospheric super-fountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive ionospheric storm effect at mid-latitudes for some storm periods. In other cases (e.g 29 October 2003), Prompt Penetration Electric Fields (PPEF), EIA expansion and large scale Traveling Ionospheric Disturbances (TIDs) were found to be present during the positive storm effect at mid-latitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45± 5. A further report on statistical analysis of ionospheric storm effects due to Corotating Interaction Region (CIR)- and Coronal Mass Ejection (CME)-driven storms was performed. The storm periods analyzed occurred during the period 2001 - 2015 which covers part of solar cycles 23 and 24. Dst≤ -30 nT and Kp≥ 3 indices were used to identify the storm periods considered. Ionospheric TEC derived from IGS stations that lie within 30°E - 40°E geographic longitude in mid, low and equatorial latitude over the African sector were used. The statistical analysis of ionospheric storm effects were compared over mid, low and equatorial latitudes in the African sector for the first time. Positive ionospheric storm effects were more prevalent during CME-driven and CIR-driven over all stations considered in this study. Negative ionospheric storm effects occurred only during CME-driven storms over mid-latitude stations and were more prevalent in summer. The other interesting finding is that for the stations considered over mid-, low, and equatorial latitudes, negative-positive ionospheric responses were only observed over low and equatorial latitudes. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low latitude stations compared to other latitude regions.
- Full Text:
- Authors: Matamba, Tshimangadzo Merline
- Date: 2018
- Subjects: Ionospheric storms , Coronal mass ejections , Corotating interaction regions , Solar flares , Global Positioning System , Ionospheric critical frequencies , Equatorial Ionization Anomaly (EIA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63991 , vital:28517
- Description: Understanding changes in the ionosphere is important for High Frequency (HF) communications and navigation systems. Ionospheric storms are the disturbances in the Earth’s upper atmosphere due to solar activities such as Coronal Mass Ejections (CMEs), Corotating interaction Regions (CIRs) and solar flares. This thesis reports for the first time on an investigation of ionospheric response to great geomagnetic storms (Disturbance storm time, Dst ≤ −350 nT) that occurred during solar cycle 23. The storm periods analysed were 29 March - 02 April 2001, 27 - 31 October 2003, 18 - 23 November 2003 and 06 - 11 November 2004. Global Navigation Satellite System (GNSS), Total Electron Content (TEC) and ionosonde critical frequency of F2 layer (foF2) data over northern hemisphere (European sector) and southern hemisphere (African sector) mid-latitudes were used to study the ionospheric responses within 15E° - 40°E longitude and ±31°- ±46° geomagnetic latitude. Mid-latitude regions within the same longitude sector in both hemispheres were selected in order to assess the contribution of the low latitude changes especially the expansion of Equatorial Ionization Anomaly (EIA) also known as the dayside ionospheric super-fountain effect during these storms. In all storm periods, both negative and positive ionospheric responses were observed in both hemispheres. Negative ionospheric responses were mainly due to changes in neutral composition, while the expansion of the EIA led to pronounced positive ionospheric storm effect at mid-latitudes for some storm periods. In other cases (e.g 29 October 2003), Prompt Penetration Electric Fields (PPEF), EIA expansion and large scale Traveling Ionospheric Disturbances (TIDs) were found to be present during the positive storm effect at mid-latitudes in both hemispheres. An increase in TEC on the 28 October 2003 was because of the large solar flare with previously determined intensity of X45± 5. A further report on statistical analysis of ionospheric storm effects due to Corotating Interaction Region (CIR)- and Coronal Mass Ejection (CME)-driven storms was performed. The storm periods analyzed occurred during the period 2001 - 2015 which covers part of solar cycles 23 and 24. Dst≤ -30 nT and Kp≥ 3 indices were used to identify the storm periods considered. Ionospheric TEC derived from IGS stations that lie within 30°E - 40°E geographic longitude in mid, low and equatorial latitude over the African sector were used. The statistical analysis of ionospheric storm effects were compared over mid, low and equatorial latitudes in the African sector for the first time. Positive ionospheric storm effects were more prevalent during CME-driven and CIR-driven over all stations considered in this study. Negative ionospheric storm effects occurred only during CME-driven storms over mid-latitude stations and were more prevalent in summer. The other interesting finding is that for the stations considered over mid-, low, and equatorial latitudes, negative-positive ionospheric responses were only observed over low and equatorial latitudes. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low latitude stations compared to other latitude regions.
- Full Text:
Mannich base metal complexes and their thiocyanate analogues as catalysts in the oxidation of Catechol
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
- Authors: Ayeni, Ayowole Olaolu
- Date: 2018
- Subjects: Mannich bases , Catechol , Catechol -- Oxidation , Thiocyanates , Catalysts
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62339 , vital:28156
- Description: The study focused on the design of new Cu(II) and Fe(III) complexes, with or without thiocyanate (NCS-), as possible candidates of catechol oxidation using 3,5-di-tert-butyl catechol (3,5-DTBC) as substrate. Two classes of Mannich bases were studied depending on the active methylene group from which they were formed, being either p-cresol or acetaminophen. The ligands were characterised by 1H and 13C NMR spectroscopy. Crystal structures of three of the ligands are newly reported, along with detailed discussion of polymorphism observed in one of the ligands, and the nature of the hydrogen within the ligands in the solid state as well as in solution. The Mannich bases behaved as bidentate (NO), tridentate (NNO) and tetradentate (NNOO) ligands on coordination to Cu(II) and Fe(III) ions in which the hydroxyl group may be protonated or deprotonated. Coordination was determined by IR spectroscopy, investigating shifts in vOH, vC-O and in vCNC of the Mannich bases. The vCNC stretching frequencies v1 and v2 of asymmetrical piperazine Mannich bases were observed to shift upward in few cases upon complexation and this is attributed to (chair-boat) conformational change. The mode of coordination of the thiocyanate was determined by IR spectroscopy. Of the forty metal complexes investigated, six groups of metal complexes were identified as follows: (i) Ma(Ln)aClb-cH2O; (ii) Ma(HLn)a(NCS)aClb; (iii) Ma(Ln)a(NCS)aClb; (iv) Ma(HLn)aClb-cH2O; (v) Ma(Ln)a(NCS)a-cH2O; (vi) Ma(HLn)a(NCS)a-cH2O where a = 1 - 2 ; b = 1 - 4, c = 1 - 8. Molar conductivity values of 4.38 - 161.77 Q-1.cm2.mol-1 for the Cu(II) and Fe(III) complexes in DMSO showed that they range from non-electrolytes to 1:1 and 1:2 electrolytes. Electronic spectra for the ligands and the complexes were conducted in DMF and DMSO. The ligands are characterised by and n→n* and n→n* transitions. Intraligand charge transfer transitions peculiar to the nitro group were observed at about 430 nm for the nitro containing ligands. On coordination, these bands overshadowed the d-d transitions particularly for the nitro-Mannich bases. On complexation, ligand to metal charge transfer transitions associated with the hydroxyl were observed between 320 - 420 nm. Charge transfer transitions associated with the thiocyanates were also observed and discussed. The d-d transitions for high spin Fe(III) complexes are spin forbidden and generally uninformative. Those of Cu(II) are spin allowed and allow tentative structural proposals. Square planar and octahedral geometry are generally prevalent in the Cu(II) complexes with trigonal bipyramidal observed in few instances. The Fe(III) complexes are generally octahedral. Thirty-nine of the forty synthesised Cu(II) and Fe(III) complexes were catalytically active on the substrate (3,5-DTBC) in DMF with turnover rates (kcat) reported in the range of 1.86 ± 0.09 to 112.32 ± 3.72 h-1. From this pool of complexes, sixteen isostructural pairs were identified in terms of geometry, molecular formula and the source of the Mannich base and the following conclusions were made: The presence of thiocyanate in the metal complexes reduce catecholase activity; the Cu(II) complexes generally have better activity but the Fe(III) complexes become more relatively active with highly electron donating groups while the Cu(II) complexes become less; dinuclear complexes have greater activity than the mononuclear.
- Full Text:
Modelling Ionospheric vertical drifts over the African low latitude region
- Dubazane, Makhosonke Berthwell
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
- Authors: Dubazane, Makhosonke Berthwell
- Date: 2018
- Subjects: Ionospheric drift , Magnetometers , Functions, Orthogonal , Neural networks (Computer science) , Ionospheric electron density -- Africa , Communication and Navigation Outage Forecasting Systems (C/NOFS)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63356 , vital:28396
- Description: Low/equatorial latitudes vertical plasma drifts and electric fields govern the formation and changes of ionospheric density structures which affect space-based systems such as communications, navigation and positioning. Dynamical and electrodynamical processes play important roles in plasma distribution at different altitudes. Because of the high variability of E × B drift in low latitude regions, coupled with various processes that sometimes originate from high latitudes especially during geomagnetic storm conditions, it is challenging to develop accurate vertical drift models. This is despite the fact that there are very few instruments dedicated to provide electric field and hence E × B drift data in low/equatorial latitude regions. To this effect, there exists no ground-based instrument for direct measurements of E×B drift data in the African sector. This study presents the first time investigation aimed at modelling the long-term variability of low latitude vertical E × B drift over the African sector using a combination of Communication and Navigation Outage Forecasting Systems (C/NOFS) and ground-based magnetometer observations/measurements during 2008-2013. Because the approach is based on the estimation of equatorial electrojet from ground-based magnetometer observations, the developed models are only valid for local daytime. Three modelling techniques have been considered. The application of Empirical Orthogonal Functions and partial least squares has been performed on vertical E × B drift modelling for the first time. The artificial neural networks that have the advantage of learning underlying changes between a set of inputs and known output were also used in vertical E × B drift modelling. Due to lack of E×B drift data over the African sector, the developed models were validated using satellite data and the climatological Scherliess-Fejer model incorporated within the International Reference Ionosphere model. Maximum correlation coefficient of ∼ 0.8 was achieved when validating the developed models with C/NOFS E × B drift observations that were not used in any model development. For most of the time, the climatological model overestimates the local daytime vertical E × B drift velocities. The methods and approach presented in this study provide a background for constructing vertical E ×B drift databases in longitude sectors that do not have radar instrumentation. This will in turn make it possible to study day-to-day variability of vertical E×B drift and hopefully lead to the development of regional and global models that will incorporate local time information in different longitude sectors.
- Full Text:
Modelling plant water use of the grassland and thicket biomes in the Eastern Cape, South Africa: towards an improved understanding of the impact of invasive alien plants on soil chemistry, biomass production and evapotranspiration
- Authors: Gwate, Onalenna
- Date: 2018
- Subjects: Grasslands -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Rangelands -- South Africa -- Eastern Cape , Range ecology-- South Africa -- Eastern Cape , Rangelands -- Water-supply , Rangelands -- Weed control , Evapotranspiration , Plant-water relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54800 , vital:26617
- Description: It is imperative to understand the strong coupling between the carbon capture process and water use to sustainably manage rangelands. Woody encroachment is undermining rangelands grass production. Evapotranspiration (ET) highlights the links between ecosystem carbon capture process and water use. It forms the biggest flux of the hydrological cycle after precipitation yet it is not well understood. The Grassland and the Albany Thicket (AT) biomes in the Eastern Cape, South Africa, provide an interesting space to study the dynamics in rangelands biomass production and the associated water use. Therefore, the main purpose of this study was to contribute towards management of rangelands by understanding the dynamics in rangeland grass production and water use. To achieve this aim, the impact of Acacia mearnsii, an invasive alien plant, on soil chemical properties and rangelands grass production was investigated. This was achieved by analysing the biophysical attributes of A. mearnsii as they related to grass production. Secondly, selected soil variables that could be used as a prognosis for landscape recovery or deterioration were evaluated. In addition, aboveground grass biomass was measured in areas cleared of A. mearnsii and regression equations were prepared to help model aboveground grass biomass in areas cleared of A. mearnsi. The thesis also explored dynamics in water vapour and energy fluxes in these two biomes using an eddy covariance system. Consequently, water vapour and energy fluxes were evaluated in order to understand landscape water use and energy partitioning in the landscape. The study also tested the application of Penman-Monteith equation based algorithms for estimating ET with micrometeorological techniques used for validation. Pursuant to this, the Penman- Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) equations were applied. In addition, some effort was devoted to improving the estimates of ET from the PMP by incorporating a direct soil evaporation component. Finally, the influence of local changes in catchment characteristics on ET was explored through the application of a variant of the Budyko framework and investigating dynamics in the evaporative index as well as applying tests for trends and shifts on ET and rainfall data to detect changes in mean quaternary catchment rainfall and ET. Results revealed that A. mearnsii affected soil chemical properties and impaired grass production in rangelands. Hence, thinning of canopies provided an optimal solution for enhanced landscape water use to sequestrate carbon, provide shade, grazing, and also wood fuel. It was also shown that across sites, ET was water limited since differences between reference ET and actual ET were large. ET was largely sensitive to vapour pressure deficit and surface conductance than to net radiation, indicating that the canopies were strongly coupled with the boundary layer. Rangeland ET was successfully simulated and evaporation from the soil was the dominant flux, hence there is scope for reducing the so-called ‘unproductive’ water use. Further, it was shown that the PML was better able to simulate ET compared to the PMP model as revealed by different model evaluation metrics such as the root mean square error, absolute mean square error and the root mean square observations standard deviation ratio. The incorporation of a soil evaporation component in the PMP model improved estimates of ET as revealed by the root mean square error. The results also indicated that both the catchment parameter (w) and the evaporative index were important in highlighting the impacts of land cover change on ET. It was also shown that, despite changes in the local environment such as catchment characteristics, global forces also affected ET at a local scale. Overall, the study demonstrated that combining remote sensing and ground based observations was important to better understand rangeland grass production and water use dynamics.
- Full Text:
- Authors: Gwate, Onalenna
- Date: 2018
- Subjects: Grasslands -- South Africa -- Eastern Cape , Invasive plants -- South Africa -- Eastern Cape , Rangelands -- South Africa -- Eastern Cape , Range ecology-- South Africa -- Eastern Cape , Rangelands -- Water-supply , Rangelands -- Weed control , Evapotranspiration , Plant-water relationships
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/54800 , vital:26617
- Description: It is imperative to understand the strong coupling between the carbon capture process and water use to sustainably manage rangelands. Woody encroachment is undermining rangelands grass production. Evapotranspiration (ET) highlights the links between ecosystem carbon capture process and water use. It forms the biggest flux of the hydrological cycle after precipitation yet it is not well understood. The Grassland and the Albany Thicket (AT) biomes in the Eastern Cape, South Africa, provide an interesting space to study the dynamics in rangelands biomass production and the associated water use. Therefore, the main purpose of this study was to contribute towards management of rangelands by understanding the dynamics in rangeland grass production and water use. To achieve this aim, the impact of Acacia mearnsii, an invasive alien plant, on soil chemical properties and rangelands grass production was investigated. This was achieved by analysing the biophysical attributes of A. mearnsii as they related to grass production. Secondly, selected soil variables that could be used as a prognosis for landscape recovery or deterioration were evaluated. In addition, aboveground grass biomass was measured in areas cleared of A. mearnsii and regression equations were prepared to help model aboveground grass biomass in areas cleared of A. mearnsi. The thesis also explored dynamics in water vapour and energy fluxes in these two biomes using an eddy covariance system. Consequently, water vapour and energy fluxes were evaluated in order to understand landscape water use and energy partitioning in the landscape. The study also tested the application of Penman-Monteith equation based algorithms for estimating ET with micrometeorological techniques used for validation. Pursuant to this, the Penman- Monteith-Leuning (PML) and Penman-Monteith-Palmer (PMP) equations were applied. In addition, some effort was devoted to improving the estimates of ET from the PMP by incorporating a direct soil evaporation component. Finally, the influence of local changes in catchment characteristics on ET was explored through the application of a variant of the Budyko framework and investigating dynamics in the evaporative index as well as applying tests for trends and shifts on ET and rainfall data to detect changes in mean quaternary catchment rainfall and ET. Results revealed that A. mearnsii affected soil chemical properties and impaired grass production in rangelands. Hence, thinning of canopies provided an optimal solution for enhanced landscape water use to sequestrate carbon, provide shade, grazing, and also wood fuel. It was also shown that across sites, ET was water limited since differences between reference ET and actual ET were large. ET was largely sensitive to vapour pressure deficit and surface conductance than to net radiation, indicating that the canopies were strongly coupled with the boundary layer. Rangeland ET was successfully simulated and evaporation from the soil was the dominant flux, hence there is scope for reducing the so-called ‘unproductive’ water use. Further, it was shown that the PML was better able to simulate ET compared to the PMP model as revealed by different model evaluation metrics such as the root mean square error, absolute mean square error and the root mean square observations standard deviation ratio. The incorporation of a soil evaporation component in the PMP model improved estimates of ET as revealed by the root mean square error. The results also indicated that both the catchment parameter (w) and the evaporative index were important in highlighting the impacts of land cover change on ET. It was also shown that, despite changes in the local environment such as catchment characteristics, global forces also affected ET at a local scale. Overall, the study demonstrated that combining remote sensing and ground based observations was important to better understand rangeland grass production and water use dynamics.
- Full Text:
Movement of coastal fishery species in Southern Africa: research trends, characterisation of behaviours and a case study on fishery implications
- Authors: Maggs, Jade Quinton
- Date: 2018
- Subjects: Fishery management -- Africa, Southern , Fisheries -- Africa, Southern , Fisheries -- Catch effort , Fisheries -- Environmental aspects , Fisheries --Monitoring , Biotelemetry , Sustainable fisheries -- Africa, Southern , Overfishing -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60574 , vital:27798
- Description: Movement of fishes is an integral part of their daily life, but has significant implications for fishery management. As with nearly all coastal countries, South Africa relies on coastal fisheries as a renewable resource, but many stocks have been overexploited for decades. Although it has long been recognised that an understanding of fish movement is necessary for effective management, it is with some difficulty that the subject has been studied in the past. In recent years, however, improvements in technology have provided the means for more in-depth investigations into fish movement. This research has revealed a range of complex movement behaviours. Movement in fishes occurs on a variety of temporal and spatial scales leading to the characteristic patterns of distribution and abundance observed in marine ecosystems. Fishes move nearly constantly in search of food, shelter or reproductive opportunities. Observations of behaviours such as long-term site fidelity, longdistance migration and natal homing are enabling ecologists to understand patterns of distribution and abundance within a species' range. Fish movement around the South African coast has been studied on numerous occasions but this has largely been confined to studies on single species. Movement behaviour of multiple species has been studied, but this has been limited to spatially localised marine protected area research. There has been little attempt in southern Africa to synthesize interspecific movement behaviour over wide spatial scales.Unprecedented concern over the biological effects of overexploitation, together with rapid technological advances in biotelemetry, have provided the impetus for much research, on a global scale, into the movement of marine animals. I reviewed 101 marine and estuarine fish movement studies from southern Africa, published from 1928 to 2014, with the aim of synthesising research trends and findings. Trends showed an increasing emphasis on fish movement research in publications in the sub-tropical and warm-temperate biogeographic regions along the south and east coasts of southern Africa. Although 63% of publications featured only marine studies, research into fine-scale habitat use in estuaries has been on the increase, concomitant with increasing accessibility of biotelemetry. Overall, 26 fish families were identified in the surveyed literature with regionally endemic sparids featuring in 32% of the publications. Ten movement themes were identified in the surveyed literature, including broad-scale movement patterns, which featured in 68% of studies, followed by fine- scale habitat usage (33%) and protected areas (26%). The most prominent phenomenon, emerging from this research, is that of partial migration, which describes the occurrence of resident and migratory behaviour within a coexisting animal population. Substantial progress has also been made in unravelling the complexities of fine-scale movements in marine reserves and habitat usage in estuaries. While this knowledge has enabled more effective management of South Africa's multi-user, multi-species fisheries, focus should now be directed at improving our understanding of the commonalities in movement behaviour, the associated driving forces behind this behaviour and the extent of movement across reserve boundaries. Mark-recapture data, collected over the past 30 years by the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORICFTP), were used to investigate broad- scale movement patterns of 30 prominent coastal fishery species (Chapter 4). Fishes were tagged with plastic dart tags along the coastline of southern Africa from Angola to Mozambique. This exercise yielded more than 10000 recaptures. The 30 chosen species represented 14 families, although 12 species belonged to a single family (Sparidae). Overall, 67% of recaptures were reported from the original tagging locality and 73% were recorded within 5 km of the tagging locality. The remaining observations extended from 6-3000 km. Movements were assigned to four distance bins (0-5 km, 6-50km, 51-500km and >500 km) and modelled with an ordinal logistic regression. Species, life-stage (juvenile/adult) and time- at-liberty were included as predictor variables. Model coefficients were then included in a cluster analysis, which produced two primary groupings of species (Category I and II), with two sub-groupings (Category IIa and IIb). Category I species were characterised by wide-ranging movements, greatest median recapture length and highest trophic levels. Category II species were characterised by residency, lower median recapture length and lower trophic levels. These findings have implications for fisheries management. Exploitation of resident species may lead to localised depletion, but their diffuse spatial distribution may offer some resilience. In contrast, even localised targeting of migratory species may pose a population level risk if individuals are known to aggregate. Life-cycle diversity or intra-population variability describes the existence of alternative strategies or tactics among coexisting individuals within an animal population (Chapter 5). Partial migration is a specific case of life-cycle diversity where coexisting groups exhibit either resident or migratory (wide-ranging) behaviour within a single population. Mark- recapture data collected under the auspices of the ORICFTP were used to investigate the occurrence and nature of life-cycle diversity in the movement behaviour of five non- diadromous fish species around the coastline of southern Africa. Among the five species were three teleosts (Category I and IIa) and two elasmobranchs (Category I). A fish was considered to have remained resident if recaptured within 0-5 km after 365 days at liberty. A fish was considered to have undertaken a wide-ranging movement if recaptured more than 50 km away from the release site in 365 days or less. A total of 1848 individuals from the five study species were recaptured during the study, of which 73% of the observations were classified as being resident. Binomial logistic regression confirmed that species, life-stage (juvenile/adult) and ecoregion were significant (p < 0.001) predictors of the probability of wide-ranging behaviour. A Gaussian model confirmed that species and ecoregion were also significant (p < 0.001) predictors of direction and distance of wide-ranging movement. However, the direction and distance of wide-ranging movements in juveniles did not differ significantly (p > 0.05) to that of adults. The median growth rate was mostly greater in wide- ranging individuals; however, this was only statistically significant (p < 0.05) in two cases. These findings provide unequivocal evidence of life-cycle diversity in five fish species, with vastly different life-histories. This ecological phenomenon may provide species resilience at the population level and needs to be considered in fisheries management initiatives. The movement of fishes is a fundamental aspect to consider when designing fishery management regimes. Unfortunately, traditional management strategies have often disregarded movement behaviour to the detriment of fish populations (Chapter 6). As a case study, the management of Lichia amia (Category I: wide-ranging) was evaluated in the context of its movement behaviour. Long-term catch-per-unit-effort (CPUE) datasets were examined for three South African recreational fishery sectors. The CPUE was standardised using generalized linear models (delta-Gamma/hurdle approach) to reduce the effect of factors other than abundance. Factors that were available for this purpose were year, month and locality/zone. Year was included in every model as the primary objective was to detect trends in abundance over time. Although standardised CPUE for all sectors showed an overall long-term decline, there was considerable variability in trends between the different recreational sectors and between datasets. Contrasting trends between competitive shore angling and general shore angling datasets were ascribed to hyperstability in competitive CPUE data. Hyperstability in this case was mostly influenced by rapidly improving technology, techniques and communication networks amongst competitive anglers. Month and locality were significant factors explaining the probability of catching L. amia. This suggests that the predictable aggregatory behaviour of this species could further compound the observed CPUE hyperstability. Although the CPUE responded positively for six years after implementation of the first minimum size and bag limits, and for one year after the decommercialisation of the species, these regulations and their amendments failed to arrest a long-term decline in the CPUE despite the ample evidence for hyperstability. It is clear from this case study that the predictable nature of wide-ranging behaviour in L. amia has made the population vulnerable to exploitation. This has led to the demise in the population, which could have been worse if not for the occurrence of intra-population variability in its movement behaviour, which may provide some measure of resilience.
- Full Text:
- Authors: Maggs, Jade Quinton
- Date: 2018
- Subjects: Fishery management -- Africa, Southern , Fisheries -- Africa, Southern , Fisheries -- Catch effort , Fisheries -- Environmental aspects , Fisheries --Monitoring , Biotelemetry , Sustainable fisheries -- Africa, Southern , Overfishing -- Africa, Southern
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60574 , vital:27798
- Description: Movement of fishes is an integral part of their daily life, but has significant implications for fishery management. As with nearly all coastal countries, South Africa relies on coastal fisheries as a renewable resource, but many stocks have been overexploited for decades. Although it has long been recognised that an understanding of fish movement is necessary for effective management, it is with some difficulty that the subject has been studied in the past. In recent years, however, improvements in technology have provided the means for more in-depth investigations into fish movement. This research has revealed a range of complex movement behaviours. Movement in fishes occurs on a variety of temporal and spatial scales leading to the characteristic patterns of distribution and abundance observed in marine ecosystems. Fishes move nearly constantly in search of food, shelter or reproductive opportunities. Observations of behaviours such as long-term site fidelity, longdistance migration and natal homing are enabling ecologists to understand patterns of distribution and abundance within a species' range. Fish movement around the South African coast has been studied on numerous occasions but this has largely been confined to studies on single species. Movement behaviour of multiple species has been studied, but this has been limited to spatially localised marine protected area research. There has been little attempt in southern Africa to synthesize interspecific movement behaviour over wide spatial scales.Unprecedented concern over the biological effects of overexploitation, together with rapid technological advances in biotelemetry, have provided the impetus for much research, on a global scale, into the movement of marine animals. I reviewed 101 marine and estuarine fish movement studies from southern Africa, published from 1928 to 2014, with the aim of synthesising research trends and findings. Trends showed an increasing emphasis on fish movement research in publications in the sub-tropical and warm-temperate biogeographic regions along the south and east coasts of southern Africa. Although 63% of publications featured only marine studies, research into fine-scale habitat use in estuaries has been on the increase, concomitant with increasing accessibility of biotelemetry. Overall, 26 fish families were identified in the surveyed literature with regionally endemic sparids featuring in 32% of the publications. Ten movement themes were identified in the surveyed literature, including broad-scale movement patterns, which featured in 68% of studies, followed by fine- scale habitat usage (33%) and protected areas (26%). The most prominent phenomenon, emerging from this research, is that of partial migration, which describes the occurrence of resident and migratory behaviour within a coexisting animal population. Substantial progress has also been made in unravelling the complexities of fine-scale movements in marine reserves and habitat usage in estuaries. While this knowledge has enabled more effective management of South Africa's multi-user, multi-species fisheries, focus should now be directed at improving our understanding of the commonalities in movement behaviour, the associated driving forces behind this behaviour and the extent of movement across reserve boundaries. Mark-recapture data, collected over the past 30 years by the Oceanographic Research Institute’s Cooperative Fish Tagging Project (ORICFTP), were used to investigate broad- scale movement patterns of 30 prominent coastal fishery species (Chapter 4). Fishes were tagged with plastic dart tags along the coastline of southern Africa from Angola to Mozambique. This exercise yielded more than 10000 recaptures. The 30 chosen species represented 14 families, although 12 species belonged to a single family (Sparidae). Overall, 67% of recaptures were reported from the original tagging locality and 73% were recorded within 5 km of the tagging locality. The remaining observations extended from 6-3000 km. Movements were assigned to four distance bins (0-5 km, 6-50km, 51-500km and >500 km) and modelled with an ordinal logistic regression. Species, life-stage (juvenile/adult) and time- at-liberty were included as predictor variables. Model coefficients were then included in a cluster analysis, which produced two primary groupings of species (Category I and II), with two sub-groupings (Category IIa and IIb). Category I species were characterised by wide-ranging movements, greatest median recapture length and highest trophic levels. Category II species were characterised by residency, lower median recapture length and lower trophic levels. These findings have implications for fisheries management. Exploitation of resident species may lead to localised depletion, but their diffuse spatial distribution may offer some resilience. In contrast, even localised targeting of migratory species may pose a population level risk if individuals are known to aggregate. Life-cycle diversity or intra-population variability describes the existence of alternative strategies or tactics among coexisting individuals within an animal population (Chapter 5). Partial migration is a specific case of life-cycle diversity where coexisting groups exhibit either resident or migratory (wide-ranging) behaviour within a single population. Mark- recapture data collected under the auspices of the ORICFTP were used to investigate the occurrence and nature of life-cycle diversity in the movement behaviour of five non- diadromous fish species around the coastline of southern Africa. Among the five species were three teleosts (Category I and IIa) and two elasmobranchs (Category I). A fish was considered to have remained resident if recaptured within 0-5 km after 365 days at liberty. A fish was considered to have undertaken a wide-ranging movement if recaptured more than 50 km away from the release site in 365 days or less. A total of 1848 individuals from the five study species were recaptured during the study, of which 73% of the observations were classified as being resident. Binomial logistic regression confirmed that species, life-stage (juvenile/adult) and ecoregion were significant (p < 0.001) predictors of the probability of wide-ranging behaviour. A Gaussian model confirmed that species and ecoregion were also significant (p < 0.001) predictors of direction and distance of wide-ranging movement. However, the direction and distance of wide-ranging movements in juveniles did not differ significantly (p > 0.05) to that of adults. The median growth rate was mostly greater in wide- ranging individuals; however, this was only statistically significant (p < 0.05) in two cases. These findings provide unequivocal evidence of life-cycle diversity in five fish species, with vastly different life-histories. This ecological phenomenon may provide species resilience at the population level and needs to be considered in fisheries management initiatives. The movement of fishes is a fundamental aspect to consider when designing fishery management regimes. Unfortunately, traditional management strategies have often disregarded movement behaviour to the detriment of fish populations (Chapter 6). As a case study, the management of Lichia amia (Category I: wide-ranging) was evaluated in the context of its movement behaviour. Long-term catch-per-unit-effort (CPUE) datasets were examined for three South African recreational fishery sectors. The CPUE was standardised using generalized linear models (delta-Gamma/hurdle approach) to reduce the effect of factors other than abundance. Factors that were available for this purpose were year, month and locality/zone. Year was included in every model as the primary objective was to detect trends in abundance over time. Although standardised CPUE for all sectors showed an overall long-term decline, there was considerable variability in trends between the different recreational sectors and between datasets. Contrasting trends between competitive shore angling and general shore angling datasets were ascribed to hyperstability in competitive CPUE data. Hyperstability in this case was mostly influenced by rapidly improving technology, techniques and communication networks amongst competitive anglers. Month and locality were significant factors explaining the probability of catching L. amia. This suggests that the predictable aggregatory behaviour of this species could further compound the observed CPUE hyperstability. Although the CPUE responded positively for six years after implementation of the first minimum size and bag limits, and for one year after the decommercialisation of the species, these regulations and their amendments failed to arrest a long-term decline in the CPUE despite the ample evidence for hyperstability. It is clear from this case study that the predictable nature of wide-ranging behaviour in L. amia has made the population vulnerable to exploitation. This has led to the demise in the population, which could have been worse if not for the occurrence of intra-population variability in its movement behaviour, which may provide some measure of resilience.
- Full Text:
Naming in Germany in the 20th century: a sociological study of naming in times of social change, with a focus on statistical problems in empirical onomastic research
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
- Authors: Huschka, Denis
- Date: 2018
- Subjects: Onomastics , Names, Personal -- Germany , Names, German -- Etymology , Names, German -- Social aspects , German language -- Etymology -- Names , German Socio Economic Panel Study (SOEP)
- Language: German , English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63054 , vital:28359
- Description: In this thesis names are used as social indicators to observe social change in Germany in the 20th century. The German Socio Economic Panel Study (SOEP) offers the rare opportunity to analyse representative survey data of first names. The empirical results of the analyses in this thesis offer a comprehensive picture on how the naming reality in Germany looks like and how naming changed in a period of about 100 years. Names can serve as social indicators. It is demonstrated how chosen names mirror social change in the German society: Name choices have become less traditional and more individual. Over time names from other world regions and cultures have found their way into the German culture. There are more different names in use today than 100 years ago and the names have become more evenly distributed over the population. Today children are less likely to share their names with many of their peers. These are signs of an increasingly individualised, transnationalised modern behaviour of the people in contemporary Germany. Almost all of these developments started earlier and tend to be more pronounced for girl’s names. The secularisation of the German society - however - did not cause substantial changes in naming over time. Christian names still are used to the greatest extent, but – possibly – not because they are regarded as being of Christian origin. The analyses of the social-structural influences on naming touch on some effects of education and status. The analyses of differences in naming between the two German states during the time of division adds some evidence to the real-life experience that naming in the communist East Germany was much more oriented towards the free western hemisphere – a kind of silent protest. Obviously naming was a possibility to distance oneself from an un-loved regime. On a methodological level referring to onomastics, the so-called „Large Number of are Events-Zone (LNRE)“, a feature of the distribution of names that has mostly been handled inappropriately up to now, is discussed with respect to its effects on name statistics when using samples. An alternative approach is proposed for the appropriate handling of this feature. , In der vorliegenden Arbeit werden Vornamen als soziale Indikatoren benutzt, um gesellschaftlichen Wandel im 20. Jahrhundert zu beschreiben. Das Soziooekonomische Panel (SOEP) bietet die seltene Möglichkeit, Umfragedaten über die Vornamen der Deutschen repräsentativ auszuwerten. Die empirischen Ergebnisse der vorliegenden Arbeit bieten einen umfassenden Einblick in die deutsche Vornamensrealität und über die Entwicklungen der Namensvergabe in 100 Jahren. Namen sind soziale Indikatoren. Es wird aufgezeigt, wie die Namensgebung den sozialen Wandel in der deutschen Gesellschaft spiegelt: Namenwahlen weisen über die Zeit weniger traditionelle Bezüge auf, sie wurden individueller. Namen aus anderen Kulturen und Ländern fanden Eingang in die deutsche Kultur. Es werden mehr verschiedene Namen benutzt als vor 100 Jahren und die typischerweise hoch konzentrierten Verteilungen der Vornamen stellen sich über die Zeit etwas weniger konzentriert dar. Heute geborene Kinder teilen ihre Namen mit anteilig weniger anderen Kindern ihrer Kohorte. Dies sind Anzeichen für eine individualisierte, transnational orientierte moderne Gesellschaft. Fast alle dieser Entwicklungen sind für Mädchennamen früher und in deutlicherem Maße zu beobachten. Die Säkularisierung der deutschen Gesellschaft hat hingegen wenig Einfluss auf die Vornamenswahlen genommen. Nach wie vor werden vor allem christliche Namen vergeben, auch wenn der christliche Bezug unter Umständen nicht mehr der maßgebliche Grund für die Auswahl ist. Die Analyse der sozialstrukturellen Einflüsse auf Namenswahlen bestätigt einige Effekte von Bildung und Status der Mütter. Die Analyse der Unterschiede in der Namensgebung der beiden deutschen Staaten während der 40 jährigen Teilung zeigt, dass der lebensweltliche Eindruck einer zunehmenden West-Orientierung der Namenswahlen ostdeutscher Eltern nicht trügt. Offenbar waren westliche Namen eine Möglichkeit, sich vom ungeliebten Regime zu distanzieren. Auf einer statistisch-methodischen Ebene wird eine bislang in der empirischen Onomastik unrichtig gehandhabte Besonderheit von Vornamensverteilungen – die Large Number of Rare Events-Zone (LNRE) – diskutiert und Lösungsvorschläge für den statistisch korrekten Umgang mit dieser Besonderheit in Gruppenvergleichen auf der Basis von Stichproben vorgelegt.
- Full Text:
Narrated experiences of the pre-termination of pregnancy counselling healthcare encounter in the Eastern Cape public health sector
- Mavuso, Jabulile Mary-Jane Jace
- Authors: Mavuso, Jabulile Mary-Jane Jace
- Date: 2018
- Subjects: Abortion counseling -- South Africa -- Eastern Cape , Abortion -- Psychological aspects , Abortion -- Social aspects , Pro-choice movement -- South Africa -- Eastern Cape , Reproductive rights -- South Africa -- Eastern Cape , Women -- Sexual behavior -- South Africa -- Eastern Cape , Women -- South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62928 , vital:28311
- Description: Research that has been conducted about experiences of pre-abortion counselling tends to investigate either womxn's1 or healthcare providers' experiences separately, with research on womxn's experiences of abortion and abortion counselling dominating this area of research. Although some of the studies on womxn's abortion experiences have explored womxn's experiences of interactions between themselves and healthcare providers, these aspects have been underreported. To my knowledge, research that also explores womxn's interactions among themselves in the waiting room has not been done. Furthermore, research that explores the pre-termination of pregnancy healthcare encounter, where womxn's and healthcare providers' experiences of waiting room interactions and of pre-abortion counselling practices are seen as interrelated, has not been conducted. Research that has been conducted among womxn's experiences show that womxn have varying experiences of pre-abortion counselling, with some finding it useful while other womxn have found it to be lacking in relevance to their specific situation or needs. Research conducted among healthcare providers also points to varying experiences, with some healthcare providers stratifying womxn's reasons for abortion according to the acceptability of the request. This study explores health service providers’ and womxn’s narrated experiences of the pre-termination of pregnancy healthcare encounter (waiting room interactions and pre-abortion counselling) in the Eastern Cape public health sector. An African feminist post-structural approach, which enables analysis of how discursive structures and power relations may underpin African womxn's experiences of oppression and resistance, was used. Fusing this approach with a narrative-discursive analysis, enabled an exploration of the discursive resources drawn upon and the power relations referred to by participants when constructing micro-narratives and accounts of their experiences of waiting room interactions and pre-abortion counselling practices. This fusion enabled an understanding of the micro (individual) and macro (social) and how they interact and come to bear on experiences of the pre-abortion counselling healthcare encounter. Womxn's micro-narratives and healthcare providers' accounts were compared for convergences and divergences in the pre-abortion counselling practices they described. The implications of these convergences and divergences and of the power relations referred to by participants for pre-abortion counselling service provision are discussed. The research referred to in this study were conducted in contexts where abortion is legal, although the conditions under which it may be accessed differ across and within contexts. This present study is contextualised by the Choice on Termination of Pregnancy Act No. 92 of 1996 which legalises abortion and stipulates that abortion counselling should be made available to womxn but should be non-mandatory and non-directive. Data were collected at three abortion facilities located in public hospitals in the Eastern Cape. Open-ended, semi-structured interviews were conducted with 30 womxn after they received pre-abortion counselling, and four healthcare providers involved in abortion service provision. Data were analysed using an extended narrative-discursive approach which entailed exploring patterns in and across participants' talk. These patterns took the form of discursive resources (discourses and the subject positions they made available, and canonical narratives), power relations, and micro-narratives and accounts of their experiences of pre-abortion counselling practices and waiting room interactions. Participants described the following pre-abortion counselling practices: information-giving practices, consent practices, administering of LARCs, a waiting period and third-party involvement. In describing these processes, participants drew on an awfulisation of abortion discourse, moralising discourses, pronatalist discourses, and liberal discourses to construct (micro-)narratives in which liberal, pastoral and authoritarian counselling practices and power relations were constructed and referred to. In their micro-narratives, most womxn described the counselling as informative, beneficial and healing whilst also describing shock, hurt, pain and distress at the various kinds of information they received. Healthcare providers drew on discourses and canonical narratives (such as the hero and personal testimony) to justify liberal, pastoral and authoritarian counselling practices which were underpinned by constructing abortion and unintended pregnancy as problematic. The pre-abortion counselling practices that were described were directive in two ways: the coercion of contraceptive uptake post-abortion, and information provision practices which effectively work to delegitimise and persuade womxn against abortion.
- Full Text:
- Authors: Mavuso, Jabulile Mary-Jane Jace
- Date: 2018
- Subjects: Abortion counseling -- South Africa -- Eastern Cape , Abortion -- Psychological aspects , Abortion -- Social aspects , Pro-choice movement -- South Africa -- Eastern Cape , Reproductive rights -- South Africa -- Eastern Cape , Women -- Sexual behavior -- South Africa -- Eastern Cape , Women -- South Africa -- Social conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62928 , vital:28311
- Description: Research that has been conducted about experiences of pre-abortion counselling tends to investigate either womxn's1 or healthcare providers' experiences separately, with research on womxn's experiences of abortion and abortion counselling dominating this area of research. Although some of the studies on womxn's abortion experiences have explored womxn's experiences of interactions between themselves and healthcare providers, these aspects have been underreported. To my knowledge, research that also explores womxn's interactions among themselves in the waiting room has not been done. Furthermore, research that explores the pre-termination of pregnancy healthcare encounter, where womxn's and healthcare providers' experiences of waiting room interactions and of pre-abortion counselling practices are seen as interrelated, has not been conducted. Research that has been conducted among womxn's experiences show that womxn have varying experiences of pre-abortion counselling, with some finding it useful while other womxn have found it to be lacking in relevance to their specific situation or needs. Research conducted among healthcare providers also points to varying experiences, with some healthcare providers stratifying womxn's reasons for abortion according to the acceptability of the request. This study explores health service providers’ and womxn’s narrated experiences of the pre-termination of pregnancy healthcare encounter (waiting room interactions and pre-abortion counselling) in the Eastern Cape public health sector. An African feminist post-structural approach, which enables analysis of how discursive structures and power relations may underpin African womxn's experiences of oppression and resistance, was used. Fusing this approach with a narrative-discursive analysis, enabled an exploration of the discursive resources drawn upon and the power relations referred to by participants when constructing micro-narratives and accounts of their experiences of waiting room interactions and pre-abortion counselling practices. This fusion enabled an understanding of the micro (individual) and macro (social) and how they interact and come to bear on experiences of the pre-abortion counselling healthcare encounter. Womxn's micro-narratives and healthcare providers' accounts were compared for convergences and divergences in the pre-abortion counselling practices they described. The implications of these convergences and divergences and of the power relations referred to by participants for pre-abortion counselling service provision are discussed. The research referred to in this study were conducted in contexts where abortion is legal, although the conditions under which it may be accessed differ across and within contexts. This present study is contextualised by the Choice on Termination of Pregnancy Act No. 92 of 1996 which legalises abortion and stipulates that abortion counselling should be made available to womxn but should be non-mandatory and non-directive. Data were collected at three abortion facilities located in public hospitals in the Eastern Cape. Open-ended, semi-structured interviews were conducted with 30 womxn after they received pre-abortion counselling, and four healthcare providers involved in abortion service provision. Data were analysed using an extended narrative-discursive approach which entailed exploring patterns in and across participants' talk. These patterns took the form of discursive resources (discourses and the subject positions they made available, and canonical narratives), power relations, and micro-narratives and accounts of their experiences of pre-abortion counselling practices and waiting room interactions. Participants described the following pre-abortion counselling practices: information-giving practices, consent practices, administering of LARCs, a waiting period and third-party involvement. In describing these processes, participants drew on an awfulisation of abortion discourse, moralising discourses, pronatalist discourses, and liberal discourses to construct (micro-)narratives in which liberal, pastoral and authoritarian counselling practices and power relations were constructed and referred to. In their micro-narratives, most womxn described the counselling as informative, beneficial and healing whilst also describing shock, hurt, pain and distress at the various kinds of information they received. Healthcare providers drew on discourses and canonical narratives (such as the hero and personal testimony) to justify liberal, pastoral and authoritarian counselling practices which were underpinned by constructing abortion and unintended pregnancy as problematic. The pre-abortion counselling practices that were described were directive in two ways: the coercion of contraceptive uptake post-abortion, and information provision practices which effectively work to delegitimise and persuade womxn against abortion.
- Full Text: