Nonlinear optical properties of metal free thio alkyl and tert-butyl phenoxy phthalocyanine
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Joseph, Otto
- Date: 2021-10
- Subjects: Nonlinear optics , Phthalocyanines , Time-dependent density functional theory , Magnetic circular dichroism , Reverse saturable absorption (RSA) , Real Time Dependent Density Functional Theory (RT-TDDFT)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190712 , vital:45021
- Description: This work reports on the nonlinear optical properties of tetra - and octa substituted phthalocyanines (Pcs) utilising pentane thiol and 4-tertbutyl phenol as substituents. Their nonlinear absorption coefficient (𝛽) and absorption cross sections were determined using the Z-scan technique with a 10 ns pulse laser at 532 nm. The molecular second order hyperpolarizability Im[γ] was observed and the following Im[γ] trend was obtained for 𝛼-H2Pc(SC5H11)4 isomers, 5.93 ×10−31 (Cs) 2.24×10−32(D2h) > 1.21×10−32(C4h) > 1.05×10−32 (C2v) esu, respectively, in chloroform. Symmetry was seen to have an effect on the observed reverse saturable absorption (RSA) response. Based on the five level model rate equation nonlinear fit of the RSA response curves and Real Time Time Dependant Density Functional Theory (RT-TDDFT) results, the singlet excited state population dynamics was found to play a significant role in producing the observed Im[γ] trend. , Thesis (MSc) -- Faculty of Science, Chemistry, 2021
- Full Text:
- Date Issued: 2021-10
Exploring visual probability teaching strategies for enhancing mathematical thinking in grade 11 classrooms
- Nghidinwa, Lavinia Tangi-Jehova
- Authors: Nghidinwa, Lavinia Tangi-Jehova
- Date: 2021-10-29
- Subjects: Mathematics Study and teaching (Secondary) Namibia , Probabilities , Visualization , Learning models (Stochastic processes) , VIPROMaths project
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192002 , vital:45187
- Description: This Namibian case study aimed to explore the use of visualisation tools associated with different teaching strategies in the teaching of probability concepts in Grade 11 by selected teachers, to promote mathematical thinking. This research project is an integral component of the VIPROMaths project whose goal is to research the effective use of visualisation strategies in the mathematics classroom in the Southern African region. As a mathematics teacher, I have observed that mathematics teaching practices in our classrooms have relatively little connection with actual mathematics and as a result, teaching misses opportunities to promote mathematical thinking. This qualitative case study is underpinned by an interpretive paradigm and it is informed by the dual coding theory. Data was collected through survey questionnaires, reflective journals, field notes, observation schedules and stimulus-recall interviews. Firstly, I piloted my study by conducting a survey with the Grade 10-12 mathematics teachers in the Khomas region. The aim of this survey was to understand and explore how teachers in the Khomas region taught probability prior to the intervention programme. The data was analysed quantitatively using descriptive statistics such as tables and bar graphs. The findings from the survey necessitated the need for an intervention programme with some teachers in the region, focused on the use of visual tools to promote mathematical thinking. Lastly, three schools were selected from which three Grade 11 mathematics teachers were chosen to take part in an intervention programme. The goal was to observe how these three teachers use visual probability teaching strategies to enhance mathematical thinking after participating in an intervention programme. Lesson observations showed that all observed teachers used visual models to generate images and used models to develop a probability idea as well as to create platforms for classroom discussions. Interviews revealed that teachers’ views towards probability have shifted from that of being the centre of knowledge to that of a facilitator. As a result, teachers used different models to build on learners’ prior knowledge, to assess whether they grasped the probability concept and extend their teaching to real-life situations. This study concluded that the teachers need to consider using mathematical models for creating a platform for discussion to ensure that their verbal explanations are in line with the visuals incorporated. Coupled with that, the teachers’ correct use of visual probability teaching strategies has the potential of enhancing learners’ mathematical thinking. Therefore, teachers need to teach the learners how to create visuals for enhancing maximise understanding of probability concepts in mathematics. Furthermore, it is hoped that the findings will be useful to mathematics teachers, scholars and educators to improve the teaching of probability. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Nghidinwa, Lavinia Tangi-Jehova
- Date: 2021-10-29
- Subjects: Mathematics Study and teaching (Secondary) Namibia , Probabilities , Visualization , Learning models (Stochastic processes) , VIPROMaths project
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192002 , vital:45187
- Description: This Namibian case study aimed to explore the use of visualisation tools associated with different teaching strategies in the teaching of probability concepts in Grade 11 by selected teachers, to promote mathematical thinking. This research project is an integral component of the VIPROMaths project whose goal is to research the effective use of visualisation strategies in the mathematics classroom in the Southern African region. As a mathematics teacher, I have observed that mathematics teaching practices in our classrooms have relatively little connection with actual mathematics and as a result, teaching misses opportunities to promote mathematical thinking. This qualitative case study is underpinned by an interpretive paradigm and it is informed by the dual coding theory. Data was collected through survey questionnaires, reflective journals, field notes, observation schedules and stimulus-recall interviews. Firstly, I piloted my study by conducting a survey with the Grade 10-12 mathematics teachers in the Khomas region. The aim of this survey was to understand and explore how teachers in the Khomas region taught probability prior to the intervention programme. The data was analysed quantitatively using descriptive statistics such as tables and bar graphs. The findings from the survey necessitated the need for an intervention programme with some teachers in the region, focused on the use of visual tools to promote mathematical thinking. Lastly, three schools were selected from which three Grade 11 mathematics teachers were chosen to take part in an intervention programme. The goal was to observe how these three teachers use visual probability teaching strategies to enhance mathematical thinking after participating in an intervention programme. Lesson observations showed that all observed teachers used visual models to generate images and used models to develop a probability idea as well as to create platforms for classroom discussions. Interviews revealed that teachers’ views towards probability have shifted from that of being the centre of knowledge to that of a facilitator. As a result, teachers used different models to build on learners’ prior knowledge, to assess whether they grasped the probability concept and extend their teaching to real-life situations. This study concluded that the teachers need to consider using mathematical models for creating a platform for discussion to ensure that their verbal explanations are in line with the visuals incorporated. Coupled with that, the teachers’ correct use of visual probability teaching strategies has the potential of enhancing learners’ mathematical thinking. Therefore, teachers need to teach the learners how to create visuals for enhancing maximise understanding of probability concepts in mathematics. Furthermore, it is hoped that the findings will be useful to mathematics teachers, scholars and educators to improve the teaching of probability. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Numerical evolution of plane gravitational waves
- Authors: Hakata, Jonathan
- Date: 2021-10
- Subjects: Gravitational waves , Space and time , Einstein field equations , de Sitter metric , Perturbed spacetime
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190248 , vital:44977
- Description: Unlike electromagnetic waves, gravitational waves self interact. This interaction is non-linear and can have very interesting properties which effect the curvature of space-time. A gravitational plane wave collider, implemented in the Python package COFFEE [20] that been developed in recent years by the Otago relativity group and implements the method of lines, can be reliably used to study this self-interaction. This was shown to work well numerically as profounded by Frauendiener, Stevens and Whale in 2014 [24]. For this reason, COFFEE will be used to study these gravitational wave propagations and subsequently collisions. The Einstein field equations are formulated as a well-posed initial boundary value problem (IBVP) in the Friedrich-Nagy gauge [26] and due to the large class of boundary conditions admitted by this framework, a variety of investigations into the propagation of plane gravitational waves could be carried out. This study focuses on the propagation of plane gravitational waves in the de Sitter (dS) space-time, which is the maximally symmetric solution of the Einstein’s vacuum field equations with a positive cosmological constant λ. There is substantial cosmological evidence that our universe is asymptotically de Sitter, yet no work, analytical nor numerical, has been done on gravitational plane waves propagating on such a space-time, mainly due to the increased complexity from the non-vanishing λ. Firstly, it is found analytically that with an arbitrary cosmological constant λ and a non-vanishing energy momentum tensor, the constraints will propagate. This means that we still have a wellposed IBVP, which is nontrivial since the Friedrich-Nagy gauge has only been shown to lead to a wellposed IBVP without matter [26]. Using this system, we consider one ingoing wave propagating on said space-time in vacuum. The area of the ingoing wave profile is varied and inferences are made about the different phenomena that arise in the curvature of space-time during the evolution. It is found that there exists a critical value of the wave’s area, ac, whereby taking the area below this value the system asymptotes to its initial state, and above the system diverges, indicating the presence of a singularity. Furthermore, we define an expansion parameter H to measure how the gravitational waves influence the accelerated expansion, generalising (numerically) results of Tsamis and Woodard. , Thesis (MSc) -- Faculty of Science, Mathematics, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Hakata, Jonathan
- Date: 2021-10
- Subjects: Gravitational waves , Space and time , Einstein field equations , de Sitter metric , Perturbed spacetime
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190248 , vital:44977
- Description: Unlike electromagnetic waves, gravitational waves self interact. This interaction is non-linear and can have very interesting properties which effect the curvature of space-time. A gravitational plane wave collider, implemented in the Python package COFFEE [20] that been developed in recent years by the Otago relativity group and implements the method of lines, can be reliably used to study this self-interaction. This was shown to work well numerically as profounded by Frauendiener, Stevens and Whale in 2014 [24]. For this reason, COFFEE will be used to study these gravitational wave propagations and subsequently collisions. The Einstein field equations are formulated as a well-posed initial boundary value problem (IBVP) in the Friedrich-Nagy gauge [26] and due to the large class of boundary conditions admitted by this framework, a variety of investigations into the propagation of plane gravitational waves could be carried out. This study focuses on the propagation of plane gravitational waves in the de Sitter (dS) space-time, which is the maximally symmetric solution of the Einstein’s vacuum field equations with a positive cosmological constant λ. There is substantial cosmological evidence that our universe is asymptotically de Sitter, yet no work, analytical nor numerical, has been done on gravitational plane waves propagating on such a space-time, mainly due to the increased complexity from the non-vanishing λ. Firstly, it is found analytically that with an arbitrary cosmological constant λ and a non-vanishing energy momentum tensor, the constraints will propagate. This means that we still have a wellposed IBVP, which is nontrivial since the Friedrich-Nagy gauge has only been shown to lead to a wellposed IBVP without matter [26]. Using this system, we consider one ingoing wave propagating on said space-time in vacuum. The area of the ingoing wave profile is varied and inferences are made about the different phenomena that arise in the curvature of space-time during the evolution. It is found that there exists a critical value of the wave’s area, ac, whereby taking the area below this value the system asymptotes to its initial state, and above the system diverges, indicating the presence of a singularity. Furthermore, we define an expansion parameter H to measure how the gravitational waves influence the accelerated expansion, generalising (numerically) results of Tsamis and Woodard. , Thesis (MSc) -- Faculty of Science, Mathematics, 2021
- Full Text:
- Date Issued: 2021-10
The impact of the BBB-EE policy instrument on wealth inequality : A case study on the banking sector of South Africa
- Moshikaro, Kei Kgaogelo Felia
- Authors: Moshikaro, Kei Kgaogelo Felia
- Date: 2021-10
- Subjects: Black Economic Empowerment (Program : South Africa) , Income distribution South Africa , South Africa Economic policy , South Africa Economic conditions 1991- , Banks and banking South Africa , South Africa. Financial Sector Regulation Act, 2017
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191035 , vital:45052
- Description: It has been recognised that, whether measured in terms of income or wealth, South Africa remains as one of the most unequal societies in the world. Reducing these high levels of inequalities has been an important area of focus through the formulation of policy instruments by South African policy makers. Within a specific focus on the South African banking sector, the objective of this research is to ascertaining the extent to which addressing inequalities was in fact achieved through the changing of wealth ownerships under the Broad Based Black Economic Empowerment policy instrument. To contextualise, the thesis surveys literature on two stylised economic hypotheses on both income and wealth to understand the potential causes of their respective inequalities. An exploration of both income, wealth measurements and their distributions in South Africa are presented, in addition to policy instruments designed to ameliorate income and wealth inequalities in South Africa. The thesis further presents brief case studies from the literature on Brazil’s success in reducing its high income inequality and the Malaysian National Economic Policy empowerment program to effect wealth economic transformation, as comparatives to the South African experience. The thesis findings indicate that contrary to the objectives of the BBB-EE instrument and wealth transfers, the program within the banking sector resulted in highly unequal wealth shares and equally high concentration levels. The richest top one per cent of individuals participating in the BEE transactions in the banking sector captured 79 per cent of the total wealth transfers, this providing indications of extremely high concentrations of wealth. Further, wealth meaningfully cumulates at only the 50 percentage level of the wealth distribution, this additionally suggesting that wealth transfers featured less in the bottom half of the wealth distribution. The banking BBB-EE wealth Gini coefficient of 0.88 is evidence of the extremely high levels of inequality that resulted from the BBB-EE program within the banking sector. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Moshikaro, Kei Kgaogelo Felia
- Date: 2021-10
- Subjects: Black Economic Empowerment (Program : South Africa) , Income distribution South Africa , South Africa Economic policy , South Africa Economic conditions 1991- , Banks and banking South Africa , South Africa. Financial Sector Regulation Act, 2017
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191035 , vital:45052
- Description: It has been recognised that, whether measured in terms of income or wealth, South Africa remains as one of the most unequal societies in the world. Reducing these high levels of inequalities has been an important area of focus through the formulation of policy instruments by South African policy makers. Within a specific focus on the South African banking sector, the objective of this research is to ascertaining the extent to which addressing inequalities was in fact achieved through the changing of wealth ownerships under the Broad Based Black Economic Empowerment policy instrument. To contextualise, the thesis surveys literature on two stylised economic hypotheses on both income and wealth to understand the potential causes of their respective inequalities. An exploration of both income, wealth measurements and their distributions in South Africa are presented, in addition to policy instruments designed to ameliorate income and wealth inequalities in South Africa. The thesis further presents brief case studies from the literature on Brazil’s success in reducing its high income inequality and the Malaysian National Economic Policy empowerment program to effect wealth economic transformation, as comparatives to the South African experience. The thesis findings indicate that contrary to the objectives of the BBB-EE instrument and wealth transfers, the program within the banking sector resulted in highly unequal wealth shares and equally high concentration levels. The richest top one per cent of individuals participating in the BEE transactions in the banking sector captured 79 per cent of the total wealth transfers, this providing indications of extremely high concentrations of wealth. Further, wealth meaningfully cumulates at only the 50 percentage level of the wealth distribution, this additionally suggesting that wealth transfers featured less in the bottom half of the wealth distribution. The banking BBB-EE wealth Gini coefficient of 0.88 is evidence of the extremely high levels of inequality that resulted from the BBB-EE program within the banking sector. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10
What is political corruption?: A philosophical analysis
- Authors: Onah, Gideon Owogeka
- Date: 2021-10-29
- Subjects: Political corruption , Political ethics , Political science Philosophy , Philp, Mark , Thompson, Dennis F (Dennis Frank), 1940- , Miller, Seumas
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192298 , vital:45213
- Description: The concept of political corruption is crucial in political discourses. Since the 1990s, there has been a massive resurgence of focus on political corruption. Definitional accounts of the concept have been proposed. This work is a critique of the accounts that have since been provided. I argue that these definitions are inadequate, offering an alternative. The predominant definition of the concept is that it refers to public officials’ violations of public office rules due to their respective interests in private gain. I consider this wrong for three reasons. First, politics includes more than the activities of public officials. Second, that is not the only behaviour that is contrary to the moral imperatives of politics. Third, the lack of political integrity is not just about acting wrongly. It also includes the possession of political vices. Observing the inadequacy of the dominant perspective, Seumas Miller offers a more comprehensive definition. He defines political corruption as any act that despoils the moral character of political actors and undermines the processes and purposes of legitimate political institutions. However, his definition is also insufficient. First, he includes some immoral non-political acts as examples of political corruption, although he agrees that political corruption entails immorality in politics. Second, he unjustifiably excludes some immoral political actions as denoting political corruption. In contrast, I define political corruption as possessing political vices or acting contrary to moral, political imperatives. This definition is a comprehensive reflection of what it means to lack political integrity. My thesis begins with a critical account of politics and its moral imperatives. That is the criteria for determining what political corruption is. , Thesis (MA) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Onah, Gideon Owogeka
- Date: 2021-10-29
- Subjects: Political corruption , Political ethics , Political science Philosophy , Philp, Mark , Thompson, Dennis F (Dennis Frank), 1940- , Miller, Seumas
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/192298 , vital:45213
- Description: The concept of political corruption is crucial in political discourses. Since the 1990s, there has been a massive resurgence of focus on political corruption. Definitional accounts of the concept have been proposed. This work is a critique of the accounts that have since been provided. I argue that these definitions are inadequate, offering an alternative. The predominant definition of the concept is that it refers to public officials’ violations of public office rules due to their respective interests in private gain. I consider this wrong for three reasons. First, politics includes more than the activities of public officials. Second, that is not the only behaviour that is contrary to the moral imperatives of politics. Third, the lack of political integrity is not just about acting wrongly. It also includes the possession of political vices. Observing the inadequacy of the dominant perspective, Seumas Miller offers a more comprehensive definition. He defines political corruption as any act that despoils the moral character of political actors and undermines the processes and purposes of legitimate political institutions. However, his definition is also insufficient. First, he includes some immoral non-political acts as examples of political corruption, although he agrees that political corruption entails immorality in politics. Second, he unjustifiably excludes some immoral political actions as denoting political corruption. In contrast, I define political corruption as possessing political vices or acting contrary to moral, political imperatives. This definition is a comprehensive reflection of what it means to lack political integrity. My thesis begins with a critical account of politics and its moral imperatives. That is the criteria for determining what political corruption is. , Thesis (MA) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10-29
Effects of elevated temperature, rainfall and soil nutrients on acacia mearnsii invasion
- Authors: Kharivha, Tshililo
- Date: 2021-10
- Subjects: Acacia mearnsii , Acacia mearnsii Effect of high temperatures on South Africa , Acacia mearnsii Climatic factors South Africa , Plant invasions South Africa , Invasive plants , Climatic changes South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/189997 , vital:44954
- Description: Climate change is associated with the risk of plant invasion hence a better understanding of the effects of elevated temperature, precipitation and soil nutrients on dominant invasive plants is needed for effective ecological planning. This study was set out to: (i) examine how elevated temperature (±2°C increase), (ii) high (above local average) and low (below local average) precipitation, (iii) elevated soil nutrient content (increase in soil N), and (iv) a combination of the above manipulations affects germination and growth of Acacia mearnsii, a dominant invasive plant in South Africa. The study further evaluated how the above-mentioned treatments affect soil chemical properties following A. mearnsii germination and growth. The above-mentioned specific objectives were tested under manipulated greenhouse conditions over six experimental months. The results indicated that the above-mentioned climate change scenarios have the potential to facilitate germination and growth of the invasive species A. mearnsii, and this is likely to proliferate its invasion in future. Results showed that seed germination was significantly high under all climate change manipulation treatments (˃50%) with highest seed germination recorded under high rainfall treatment (64%). Plant height was significantly higher under high temperature and high rainfall treatments throughout all the experimental months, though it was lowest under high nitrogen and combined treatment with high rainfall. The numbers of branches were high under higher temperature and low rainfall treatments than under high rainfall, high nitrogen and both combined treatments of low and high rainfall. Relative to the control, plants grown under climate change scenarios increased their root lengths, but this varied across different treatments. Total dry biomass was relatively high under high temperature treatment (0,7 g). Lower plant dry biomass was observed under low and high rainfall treatments (0,4 g), high nitrogen and combined treatments with both low and high rainfall treatments (0,1 g). Concerning the effects of climate change scenarios on soil chemical properties, soil pH levels were significantly higher after A. mearnsii germination and growth than before the experiment was setup. Soil resistivity was significantly higher in climate change treatments receiving nitrogen and combined treatments of low rainfall than other treatments and the soils before experiment. Soil total P was significantly higher in all the climate change treatments after A. mearnsii germination experiment than the before experiment soils. Soils receiving high temperature, high nitrogen, and combined treatment of low rainfall had significantly higher soil total N than other treatments and the before experiment soils. Soil total C was significantly higher in soils receiving high temperature, high nitrogen, and combined treatment of low rainfall after A. mearnsii germination than other treatments and before experiment soils. The findings suggest that future climate change scenarios of increased temperature and rainfall with soil nutrients could considerably enhance growth and germination success of the invasive plant A. mearnsii. Similarly, climate change scenarios could enhance some soil nutrient properties, which in turn, is likely to give the invasive plant A. mearnsii a germination and growth advantage. These results are the first in South Africa to show that future climate changes have the potential to facilitate A. mearnsii germination and growth, making it more invasive. The findings have implications for invasive plants management, especially action for managing the plant through clearing of the plant in sensitive ecosystems (e.g. riparian systems). , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Kharivha, Tshililo
- Date: 2021-10
- Subjects: Acacia mearnsii , Acacia mearnsii Effect of high temperatures on South Africa , Acacia mearnsii Climatic factors South Africa , Plant invasions South Africa , Invasive plants , Climatic changes South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/189997 , vital:44954
- Description: Climate change is associated with the risk of plant invasion hence a better understanding of the effects of elevated temperature, precipitation and soil nutrients on dominant invasive plants is needed for effective ecological planning. This study was set out to: (i) examine how elevated temperature (±2°C increase), (ii) high (above local average) and low (below local average) precipitation, (iii) elevated soil nutrient content (increase in soil N), and (iv) a combination of the above manipulations affects germination and growth of Acacia mearnsii, a dominant invasive plant in South Africa. The study further evaluated how the above-mentioned treatments affect soil chemical properties following A. mearnsii germination and growth. The above-mentioned specific objectives were tested under manipulated greenhouse conditions over six experimental months. The results indicated that the above-mentioned climate change scenarios have the potential to facilitate germination and growth of the invasive species A. mearnsii, and this is likely to proliferate its invasion in future. Results showed that seed germination was significantly high under all climate change manipulation treatments (˃50%) with highest seed germination recorded under high rainfall treatment (64%). Plant height was significantly higher under high temperature and high rainfall treatments throughout all the experimental months, though it was lowest under high nitrogen and combined treatment with high rainfall. The numbers of branches were high under higher temperature and low rainfall treatments than under high rainfall, high nitrogen and both combined treatments of low and high rainfall. Relative to the control, plants grown under climate change scenarios increased their root lengths, but this varied across different treatments. Total dry biomass was relatively high under high temperature treatment (0,7 g). Lower plant dry biomass was observed under low and high rainfall treatments (0,4 g), high nitrogen and combined treatments with both low and high rainfall treatments (0,1 g). Concerning the effects of climate change scenarios on soil chemical properties, soil pH levels were significantly higher after A. mearnsii germination and growth than before the experiment was setup. Soil resistivity was significantly higher in climate change treatments receiving nitrogen and combined treatments of low rainfall than other treatments and the soils before experiment. Soil total P was significantly higher in all the climate change treatments after A. mearnsii germination experiment than the before experiment soils. Soils receiving high temperature, high nitrogen, and combined treatment of low rainfall had significantly higher soil total N than other treatments and the before experiment soils. Soil total C was significantly higher in soils receiving high temperature, high nitrogen, and combined treatment of low rainfall after A. mearnsii germination than other treatments and before experiment soils. The findings suggest that future climate change scenarios of increased temperature and rainfall with soil nutrients could considerably enhance growth and germination success of the invasive plant A. mearnsii. Similarly, climate change scenarios could enhance some soil nutrient properties, which in turn, is likely to give the invasive plant A. mearnsii a germination and growth advantage. These results are the first in South Africa to show that future climate changes have the potential to facilitate A. mearnsii germination and growth, making it more invasive. The findings have implications for invasive plants management, especially action for managing the plant through clearing of the plant in sensitive ecosystems (e.g. riparian systems). , Thesis (MSc) -- Faculty of Science, Environmental Science, 2021
- Full Text:
- Date Issued: 2021-10
Ecological infrastructure importance for drought mitigation in rural South African catchments: the Cacadu Catchment case example
- Authors: Xoxo, Beauten Sinetemba
- Date: 2021-10
- Subjects: Sustainable Development Goals , Water security South Africa , Remote sensing , Watershed restoration South Africa , Restoration ecology South Africa , Ecosystem services South Africa , SDG 15.3.1
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191203 , vital:45070
- Description: Water scarcity is recognised as one of the significant challenges facing many countries, including South Africa. The threat of water scarcity is exacerbated by the coupled impacts of climate and anthropogenic drivers. Ongoing droughts and continued land cover change and degradation influence the ability of catchments to partition rainwater runoff, thereby affecting streamflow returns. However, quantifying land degradation accurately remains a challenge. This thesis used the theoretical lens of investing in ecological infrastructure to improve the drought mitigation function in rural catchments. This theoretical framework allows for a social-ecological systems approach to understand and facilitate science-based strategies for promoting ecosystem recovery. Specifically, this study aimed to explore the role and benefit of ecological infrastructure for improving drought mitigation, and consequently, water security for rural communities. Thus, this study sought to assess the consequences of human actions to catchment health status using the 15th Sustainable Development Goal indicator for the proportion of degraded land over the total land area as a surrogate. Secondly, hydrological modelling was used to describe how different land covers influence catchment hydrology, which related to how ecological infrastructure enables drought risk-reduction for mitigation regulation. Finally, this study developed a spatial prioritisation plan for restoration to improve drought mitigation for four focal ecological infrastructure (EI) categories (i.e. wetlands, riparian margins, abandoned agricultural fields and grasslands). The focal EI categories were selected for their importance in delivering water-related ecosystem services when sustainably managed. Chapter 1 sets the scene (i.e. provides the study background) and Chapter 2 provides a review of the literature. In Chapter 3, the recently released global GIS toolbox (TRENDS.EARTH) was used for tracking land change and for assessing the SDG 15.3.1 degradation indicator of i.e. Cacadu catchment over 15 years at a 300 m resolution. The results showed a declining trend in biomass productivity within the Cacadu catchment led to moderate degradation, with 16.79% of the total landscape degraded, which was determined by the pugin using the one-out, all-out rule. The incidence of degradation was detected in middle reaches of the catchment (i.e. S10F-J), while some improvement was detected in upper reaches (S10A-C) and lower reaches (S10J). In Chapter 4, a GIS-based Analytic Hierarchical Process (AHP) based on community stakeholder priorities, open-access spatial datasets and expert opinions, was used to identify EI focal areas that are best suitable for restoration to increase the drought mitigation capacity of the Cacadu catchment. The collected datasets provided three broad criteria (ecosystem health, water provision and social benefit) for establishing the AHP model using 12 spatial attributes. Prioritisation results show that up to 89% of the Cacadu catchment is suitable for restoration to improve drought mitigation. Catchments S10B-D, and S10F, S10G and S10J were highly prioritised while S10A, S10E and S10H received low priority, due to improving environmental conditions and low hydrological potential. Areas that were prioritised with consideration for local livelihoods overlap the areas for drought mitigation and form a network of villages from the middle to lower catchment reaches. Prioritised restoration areas with a consideration of societal benefit made up 0.56% of wetlands, 4.27% of riparian margins, 92.06% of abandoned croplands, and 51.86% of grasslands. Chapter 5 reports on use of the Pitman groundwater model to help understand the influence of land modification on catchment hydrology, and highlight the role of restoration interventions. The Cacadu catchment is ungauged, therefore the neighbouring Indwe catchment was used for parameter transfer through a spatial regionalisation technique. Results suggest that degradation increases surface runoff and aggravates recharge reduction, thereby reducing streamflow during low flow periods. In areas where there is natural land cover recovery, the Pitman Model simulated similar dry season streamflow to the natural land cover. Combining the outcomes from the three assessments allowed the study to highlight the role and benefits of ecological infrastructure in terms of drought mitigation. Study findings were interpreted to make recommendations for the role and benefit of ecological infrastructure for drought mitigation at a landscape scale and tertiary catchment level, within the context of available management options. The results support the notion that multiple science data sources can promote investments in ecological infrastructure. However, better spatial and temporal resolution datasets at a national level are still needed to improve the accuracy of studies such as the one outlined in this thesis. The study recommends adopting better ecosystem protection approaches and collaborative governance at multiple levels to reduce the vulnerability of rural communities to drought impacts. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Xoxo, Beauten Sinetemba
- Date: 2021-10
- Subjects: Sustainable Development Goals , Water security South Africa , Remote sensing , Watershed restoration South Africa , Restoration ecology South Africa , Ecosystem services South Africa , SDG 15.3.1
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191203 , vital:45070
- Description: Water scarcity is recognised as one of the significant challenges facing many countries, including South Africa. The threat of water scarcity is exacerbated by the coupled impacts of climate and anthropogenic drivers. Ongoing droughts and continued land cover change and degradation influence the ability of catchments to partition rainwater runoff, thereby affecting streamflow returns. However, quantifying land degradation accurately remains a challenge. This thesis used the theoretical lens of investing in ecological infrastructure to improve the drought mitigation function in rural catchments. This theoretical framework allows for a social-ecological systems approach to understand and facilitate science-based strategies for promoting ecosystem recovery. Specifically, this study aimed to explore the role and benefit of ecological infrastructure for improving drought mitigation, and consequently, water security for rural communities. Thus, this study sought to assess the consequences of human actions to catchment health status using the 15th Sustainable Development Goal indicator for the proportion of degraded land over the total land area as a surrogate. Secondly, hydrological modelling was used to describe how different land covers influence catchment hydrology, which related to how ecological infrastructure enables drought risk-reduction for mitigation regulation. Finally, this study developed a spatial prioritisation plan for restoration to improve drought mitigation for four focal ecological infrastructure (EI) categories (i.e. wetlands, riparian margins, abandoned agricultural fields and grasslands). The focal EI categories were selected for their importance in delivering water-related ecosystem services when sustainably managed. Chapter 1 sets the scene (i.e. provides the study background) and Chapter 2 provides a review of the literature. In Chapter 3, the recently released global GIS toolbox (TRENDS.EARTH) was used for tracking land change and for assessing the SDG 15.3.1 degradation indicator of i.e. Cacadu catchment over 15 years at a 300 m resolution. The results showed a declining trend in biomass productivity within the Cacadu catchment led to moderate degradation, with 16.79% of the total landscape degraded, which was determined by the pugin using the one-out, all-out rule. The incidence of degradation was detected in middle reaches of the catchment (i.e. S10F-J), while some improvement was detected in upper reaches (S10A-C) and lower reaches (S10J). In Chapter 4, a GIS-based Analytic Hierarchical Process (AHP) based on community stakeholder priorities, open-access spatial datasets and expert opinions, was used to identify EI focal areas that are best suitable for restoration to increase the drought mitigation capacity of the Cacadu catchment. The collected datasets provided three broad criteria (ecosystem health, water provision and social benefit) for establishing the AHP model using 12 spatial attributes. Prioritisation results show that up to 89% of the Cacadu catchment is suitable for restoration to improve drought mitigation. Catchments S10B-D, and S10F, S10G and S10J were highly prioritised while S10A, S10E and S10H received low priority, due to improving environmental conditions and low hydrological potential. Areas that were prioritised with consideration for local livelihoods overlap the areas for drought mitigation and form a network of villages from the middle to lower catchment reaches. Prioritised restoration areas with a consideration of societal benefit made up 0.56% of wetlands, 4.27% of riparian margins, 92.06% of abandoned croplands, and 51.86% of grasslands. Chapter 5 reports on use of the Pitman groundwater model to help understand the influence of land modification on catchment hydrology, and highlight the role of restoration interventions. The Cacadu catchment is ungauged, therefore the neighbouring Indwe catchment was used for parameter transfer through a spatial regionalisation technique. Results suggest that degradation increases surface runoff and aggravates recharge reduction, thereby reducing streamflow during low flow periods. In areas where there is natural land cover recovery, the Pitman Model simulated similar dry season streamflow to the natural land cover. Combining the outcomes from the three assessments allowed the study to highlight the role and benefits of ecological infrastructure in terms of drought mitigation. Study findings were interpreted to make recommendations for the role and benefit of ecological infrastructure for drought mitigation at a landscape scale and tertiary catchment level, within the context of available management options. The results support the notion that multiple science data sources can promote investments in ecological infrastructure. However, better spatial and temporal resolution datasets at a national level are still needed to improve the accuracy of studies such as the one outlined in this thesis. The study recommends adopting better ecosystem protection approaches and collaborative governance at multiple levels to reduce the vulnerability of rural communities to drought impacts. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
Queer as Africa: Representations of queer lives in selected Nigerian, Kenyan, and South African literature and film
- Authors: Wilson, Jon Stephen Edward
- Date: 2021-10-29
- Subjects: Africans in literature , Africans in motion pictures , Homosexuality in literature , Homosexuality in motion pictures , Sexual minorities in literature , Sexual minorities in motion pictures , African literature History and criticism , Motion pictures, African History and criticism , Sexual minorities South Africa Public opinion , Sexual minorities Kenya Public opinion , Sexual minorities Nigeria Public opinion , Sexual minorities South Africa Social conditions , Sexual minorities Kenya Social conditions , Sexual minorities Nigeria Social conditions
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/187428 , vital:44651
- Description: This thesis contests the notion that nonnormative sexualities are ‘un-African’ by examining a range of representations of queer African lives on film and in literature, produced by Africans for Africans, as a means to interrogate the role played by the interconnected histories of colonialism, religion, and the policing of queer intimacy, specifically in Kenya, Nigeria, and South Africa. Through a close reading of a selection of texts from these three countries, this thesis takes a cultural-historical approach to exploring the complex struggles engaged in by queer people in Africa to protections under the law, and to represent themselves in literary and cinematic narratives. The first chapter is focused on the Kenyan film Rafiki (2018), directed by Wanuri Kahiu, which tells the story of queer love between two young Kenyan women who face the vehement condemnation of their relationship from their homophobic community. The film was banned in Kenya, but the director was granted a temporary injunction by Kenya’s high court in order for it to be screened in Nairobi. This made Rafiki the first queer film ever to be screened in Kenya, and viable for an Academy Award nomination. The second chapter focuses on the bold assertion of a queer African identity through the short story collections Queer Africa: New and Collected Fiction (2013) and Queer Africa 2: New Stories (2017). Written by various authors from the African continent, and compiled and edited by Karen Martin and Makhosazana Xaba, both collections offer a wide variety of fictional narratives focused on queer experiences in Africa. The second chapter has a focus on stories from Kenyan and Nigerian authors and explores notions of home, queer belonging, and visibility. The third chapter presents a close reading of the South African film Inxeba (2017), also known as The Wound, directed by John Trengove and adapted by Trengove and Thando Mgqolozana from Mgqolozana’s novel, A Man Who Is Not A Man (2009). The film depicts the traditional Xhosa initiation ritual, ulwaluko, and is set in the rural Eastern Cape. Inxeba is an important case study in the history of queer representation in Africa, as the film hit a nerve with many, interrogating what South Africans believe about culture, traditions, masculinity, and the right of artists to represent sacred ritual in art. This thesis pays attention to the historical entanglements between homophobia, imperialism, and Christianity – relationships that continue to affect the experiences of queer people in Africa and attitudes towards them and interrogates why queer individuals are still being left out of efforts towards creating a new normal in postcolonial Africa. This thesis suggests that increased visibility is a key aspect of queer activism in Africa – through the act of representation, sharing lived experiences, and telling queer stories. , Thesis (MA) -- Faculty of Humanities, Literary Studies in English, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Wilson, Jon Stephen Edward
- Date: 2021-10-29
- Subjects: Africans in literature , Africans in motion pictures , Homosexuality in literature , Homosexuality in motion pictures , Sexual minorities in literature , Sexual minorities in motion pictures , African literature History and criticism , Motion pictures, African History and criticism , Sexual minorities South Africa Public opinion , Sexual minorities Kenya Public opinion , Sexual minorities Nigeria Public opinion , Sexual minorities South Africa Social conditions , Sexual minorities Kenya Social conditions , Sexual minorities Nigeria Social conditions
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/187428 , vital:44651
- Description: This thesis contests the notion that nonnormative sexualities are ‘un-African’ by examining a range of representations of queer African lives on film and in literature, produced by Africans for Africans, as a means to interrogate the role played by the interconnected histories of colonialism, religion, and the policing of queer intimacy, specifically in Kenya, Nigeria, and South Africa. Through a close reading of a selection of texts from these three countries, this thesis takes a cultural-historical approach to exploring the complex struggles engaged in by queer people in Africa to protections under the law, and to represent themselves in literary and cinematic narratives. The first chapter is focused on the Kenyan film Rafiki (2018), directed by Wanuri Kahiu, which tells the story of queer love between two young Kenyan women who face the vehement condemnation of their relationship from their homophobic community. The film was banned in Kenya, but the director was granted a temporary injunction by Kenya’s high court in order for it to be screened in Nairobi. This made Rafiki the first queer film ever to be screened in Kenya, and viable for an Academy Award nomination. The second chapter focuses on the bold assertion of a queer African identity through the short story collections Queer Africa: New and Collected Fiction (2013) and Queer Africa 2: New Stories (2017). Written by various authors from the African continent, and compiled and edited by Karen Martin and Makhosazana Xaba, both collections offer a wide variety of fictional narratives focused on queer experiences in Africa. The second chapter has a focus on stories from Kenyan and Nigerian authors and explores notions of home, queer belonging, and visibility. The third chapter presents a close reading of the South African film Inxeba (2017), also known as The Wound, directed by John Trengove and adapted by Trengove and Thando Mgqolozana from Mgqolozana’s novel, A Man Who Is Not A Man (2009). The film depicts the traditional Xhosa initiation ritual, ulwaluko, and is set in the rural Eastern Cape. Inxeba is an important case study in the history of queer representation in Africa, as the film hit a nerve with many, interrogating what South Africans believe about culture, traditions, masculinity, and the right of artists to represent sacred ritual in art. This thesis pays attention to the historical entanglements between homophobia, imperialism, and Christianity – relationships that continue to affect the experiences of queer people in Africa and attitudes towards them and interrogates why queer individuals are still being left out of efforts towards creating a new normal in postcolonial Africa. This thesis suggests that increased visibility is a key aspect of queer activism in Africa – through the act of representation, sharing lived experiences, and telling queer stories. , Thesis (MA) -- Faculty of Humanities, Literary Studies in English, 2021
- Full Text:
- Date Issued: 2021-10-29
Re-imagining the use of the abacus as a visualization tool to develop number sense in Grade 3 learners
- Authors: Elifas, Taimi Ndinelago
- Date: 2021-10-29
- Subjects: Abacus , Mathematics Study and teaching (Elementary) Namibia , Visual learning , Teaching Aids and devices , Constructivism (Education) , Effective teaching Namibia
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191953 , vital:45182
- Description: The poor performance of learners in mathematics has long been a matter of concern in Namibia. After more than three decades after independence, the country's education system is still seeking ways of addressing the high rate of poor performance in mathematics. Research previously conducted pointed out the lack of number sense in learners, as one of the contributing factors to the poor performance in mathematics. This research study is a contribution towards using the abacus as a visualization tool to develop number sense in the Foundation Phase. The study was premised on the thought – supported by literature – that effective use of concrete equipment and manipulatives, of which the abacus is part of, does affect the teaching and learning of number sense. The study further examines the use of the abacus as a visualization tool to develop number sense by the four selected Grade 3 teachers. The study argues that the effective use of the abacus develops number sense in learners. This study was framed as a multiple case study that was grounded within an interpretive paradigm and informed by the constructivist learning theory. The qualitative data of this study were collected using questionnaires, observation, reflective journals, and semi-structured interviews. The data were then analyzed using thematic analysis and an analytical tool developed from relevant literature. A survey was conducted using 50 Foundation Phase teachers in the //Kharas region, while the intervention programme consisted of four purposively selected teachers from the four primary schools in the Kalahari circuit in the Keetmanshoop district. The findings of this study revealed that the majority of teachers were not aware of abacus use in teaching mathematics before the intervention programme. It was also revealed that the few teachers that use the abacus as a visualization tool to develop number sense, employ it as a counting tool for explaining certain concepts and as well as for teaching simple arithmetic. In this research study, the selected teachers use the abacus to link the abstract mathematics content to a concrete way of doing mathematics. In the absence of the abacus in classrooms, various manipulatives are used to develop learners’ number sense. Mathematical games, verbalizing mathematics concepts, and drawing pictures to visualize abstract concepts among others are used by the selected teachers to enhance the development of number sense in the Foundation Phase. The use of the abacus by the selected teachers effectively fostered the visualization process and the conceptual understanding of number sense in learners. Through the abacus, teachers led their learners into visualizing number sense concepts such as subitizing, computing, performing mental mathematics and physical representation of numbers in different ways. The abacus was used by teachers to enhance listening skills, improve concentration and strengthen the memory of learners. On the other hand, the study also revealed that despite the various benefits of the abacus, it is time consuming. The lack of abacus use in previous grades has a huge impact on the use of it and the development of learners’ number sense in the grades being studied in this research study. Teachers are recommended to make their own abacuses, encourage learners to make their own abacuses from the readily available materials, and to allow the learners to realize that the mathematics they are doing in classrooms is around them. The use of re-imagining, re-envisioning, re-conceptualizing and re-examining of so-called ‘old teaching tools’ such as the abacus, needs to be encouraged through in-service and pre-service teacher training programmes. The study concludes that the use of traditional algorithm methods do not promote conceptual understanding and visual strategies for Foundation Phase learners and should be discouraged. It is hoped that this study will contribute towards improving the practices of mathematics teachers primarily in the Keetmanshoop district, //Kharas Region and in the rest our Namibian schools. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Elifas, Taimi Ndinelago
- Date: 2021-10-29
- Subjects: Abacus , Mathematics Study and teaching (Elementary) Namibia , Visual learning , Teaching Aids and devices , Constructivism (Education) , Effective teaching Namibia
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191953 , vital:45182
- Description: The poor performance of learners in mathematics has long been a matter of concern in Namibia. After more than three decades after independence, the country's education system is still seeking ways of addressing the high rate of poor performance in mathematics. Research previously conducted pointed out the lack of number sense in learners, as one of the contributing factors to the poor performance in mathematics. This research study is a contribution towards using the abacus as a visualization tool to develop number sense in the Foundation Phase. The study was premised on the thought – supported by literature – that effective use of concrete equipment and manipulatives, of which the abacus is part of, does affect the teaching and learning of number sense. The study further examines the use of the abacus as a visualization tool to develop number sense by the four selected Grade 3 teachers. The study argues that the effective use of the abacus develops number sense in learners. This study was framed as a multiple case study that was grounded within an interpretive paradigm and informed by the constructivist learning theory. The qualitative data of this study were collected using questionnaires, observation, reflective journals, and semi-structured interviews. The data were then analyzed using thematic analysis and an analytical tool developed from relevant literature. A survey was conducted using 50 Foundation Phase teachers in the //Kharas region, while the intervention programme consisted of four purposively selected teachers from the four primary schools in the Kalahari circuit in the Keetmanshoop district. The findings of this study revealed that the majority of teachers were not aware of abacus use in teaching mathematics before the intervention programme. It was also revealed that the few teachers that use the abacus as a visualization tool to develop number sense, employ it as a counting tool for explaining certain concepts and as well as for teaching simple arithmetic. In this research study, the selected teachers use the abacus to link the abstract mathematics content to a concrete way of doing mathematics. In the absence of the abacus in classrooms, various manipulatives are used to develop learners’ number sense. Mathematical games, verbalizing mathematics concepts, and drawing pictures to visualize abstract concepts among others are used by the selected teachers to enhance the development of number sense in the Foundation Phase. The use of the abacus by the selected teachers effectively fostered the visualization process and the conceptual understanding of number sense in learners. Through the abacus, teachers led their learners into visualizing number sense concepts such as subitizing, computing, performing mental mathematics and physical representation of numbers in different ways. The abacus was used by teachers to enhance listening skills, improve concentration and strengthen the memory of learners. On the other hand, the study also revealed that despite the various benefits of the abacus, it is time consuming. The lack of abacus use in previous grades has a huge impact on the use of it and the development of learners’ number sense in the grades being studied in this research study. Teachers are recommended to make their own abacuses, encourage learners to make their own abacuses from the readily available materials, and to allow the learners to realize that the mathematics they are doing in classrooms is around them. The use of re-imagining, re-envisioning, re-conceptualizing and re-examining of so-called ‘old teaching tools’ such as the abacus, needs to be encouraged through in-service and pre-service teacher training programmes. The study concludes that the use of traditional algorithm methods do not promote conceptual understanding and visual strategies for Foundation Phase learners and should be discouraged. It is hoped that this study will contribute towards improving the practices of mathematics teachers primarily in the Keetmanshoop district, //Kharas Region and in the rest our Namibian schools. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
An analysis of selected Grade 8 mathematics teachers’ use of gestures as visualisation tools to support mathematical meaning-making
- Authors: Haipinge, David Tuhafeni
- Date: 2021-10-29
- Subjects: Gesture , Gesture in mathematics education , Visual learning , Visualization , Mathematics Study and teaching (Secondary) Namibia
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191969 , vital:45184
- Description: The purpose of this Namibian case study was to investigate how different types of gestures are used to support the construction of mathematical meaning making in teaching and learning. Gestures of three selected Grade 8 mathematics teachers were observed and analysed. This study was intended to answer the following research question: how do selected Grade 8 mathematics teachers use gestures as visualisation tools to support mathematical meaning making? The study was framed by an enactivist perspective and the research was oriented in the interpretive paradigm. Data were collected through video-recorded observations of three selected teachers and through stimulus recall interviews. In order to generate rich data and support validity, five lessons per selected teacher were video recorded. The study found that the participating teachers incorporated a variety of mathematical gestures into their lessons in order to support and provide mathematical meaning. Further, this study found that gestures facilitated meaning making in mathematics. The findings in the study suggest a need for mathematics teachers to be trained in using gestures appropriately to communicate mathematically in their lessons. In addition, this study discovered a new type of gesture – the overlapping gesture in addition to McNeill's (1992) types, namely: pointing gestures, metaphor gestures, beating gestures and iconic gestures. This case study also showed that the more experienced the teachers are, the more mathematical gestures they produce during their mathematics lessons. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Haipinge, David Tuhafeni
- Date: 2021-10-29
- Subjects: Gesture , Gesture in mathematics education , Visual learning , Visualization , Mathematics Study and teaching (Secondary) Namibia
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191969 , vital:45184
- Description: The purpose of this Namibian case study was to investigate how different types of gestures are used to support the construction of mathematical meaning making in teaching and learning. Gestures of three selected Grade 8 mathematics teachers were observed and analysed. This study was intended to answer the following research question: how do selected Grade 8 mathematics teachers use gestures as visualisation tools to support mathematical meaning making? The study was framed by an enactivist perspective and the research was oriented in the interpretive paradigm. Data were collected through video-recorded observations of three selected teachers and through stimulus recall interviews. In order to generate rich data and support validity, five lessons per selected teacher were video recorded. The study found that the participating teachers incorporated a variety of mathematical gestures into their lessons in order to support and provide mathematical meaning. Further, this study found that gestures facilitated meaning making in mathematics. The findings in the study suggest a need for mathematics teachers to be trained in using gestures appropriately to communicate mathematically in their lessons. In addition, this study discovered a new type of gesture – the overlapping gesture in addition to McNeill's (1992) types, namely: pointing gestures, metaphor gestures, beating gestures and iconic gestures. This case study also showed that the more experienced the teachers are, the more mathematical gestures they produce during their mathematics lessons. , Thesis (MEd) -- Faculty of Education, Education, 2021
- Full Text:
- Date Issued: 2021-10-29
Exploring learners’ engagement with literacy in a book club
- Authors: Jamieson, Vuyokazi
- Date: 2022-04-08
- Subjects: Book clubs (Discussion groups) South Africa Makhanda , Literacy South Africa Makhanda , High school students Books and reading South Africa Makhanda , Books and reading South Africa Makhanda , Reading, Psychology of , Service learning South Africa Makhanda , Critical realism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263601 , vital:53642
- Description: This study observes the literacy engagement of a group of learners enrolled in Grades 8–10 in Nombulelo High School, a poorly-resourced school in the city of Makhanda in the Eastern Cape, South Africa. The learners participated in a book club hosted and run by St Andrew’s College, a privileged independent school, as a community engagement initiative. The idea of extending literacy engagement and engagement with written texts beyond textbooks used in schools is critical for learners with ambitions to enter higher education. Studying at a university requires a lot of reading, and if reading has not been taken up as a practice that involves more than ‘text consulting’ (Geisler, 1994) students will be unlikely to read the number of texts required of them. Studies (see Geisler, 1994 for an overview) have shown how the literacy of the university is very different to school based literacies. The assumption behind the study on which this thesis reports is that engagement with fictional texts might promote reading and bring about understandings of this activity as enjoyable and not a task only associated with schooling. The study is underpinned by a critical realist philosophy which allowed for the identification of structures and mechanisms that led to the emergence of literacy events in learners’ lives and to their experiences and observations of those events. The study was guided by the following questions: How do learners from a poorly-resourced high school engage around fictional texts in the context of a book club? What enables or constrains this engagement? The study was impacted by the Covid-19 pandemic in that lockdown requirements meant that learners from St Andrew’s College could not participate in the book club as much as anticipated initially as they had been forced to return home to pursue online learning. Learners from Nombuelo High School were, however, granted access to College premises, where they met in the school library following strict Covid protocols. The study draws on in-depth interviews, observations and document analysis of five learners from Nombulelo High School who participated in the book club, as well as on book reviews they wrote for the book club website. The critical realist analysis allows for the identification of mechanisms in learners’ homes and communities that enable literacies, including those that are screen-based such as using a computer, mobile phones and other technologies. This study found evidence of challenges regarding school based texts, reading fictional texts and viewing it as an enrichment of the school project. Because of children were African the emergence of communal practices and story telling is woven throughout the results section. However, is an example of the complexity of social and economic challenges facing South African marginalised schools. , Thesis (MEd) -- Faculty of Education, Centre for Higher Education Research, 2022
- Full Text:
- Date Issued: 2022-04-08
- Authors: Jamieson, Vuyokazi
- Date: 2022-04-08
- Subjects: Book clubs (Discussion groups) South Africa Makhanda , Literacy South Africa Makhanda , High school students Books and reading South Africa Makhanda , Books and reading South Africa Makhanda , Reading, Psychology of , Service learning South Africa Makhanda , Critical realism
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/263601 , vital:53642
- Description: This study observes the literacy engagement of a group of learners enrolled in Grades 8–10 in Nombulelo High School, a poorly-resourced school in the city of Makhanda in the Eastern Cape, South Africa. The learners participated in a book club hosted and run by St Andrew’s College, a privileged independent school, as a community engagement initiative. The idea of extending literacy engagement and engagement with written texts beyond textbooks used in schools is critical for learners with ambitions to enter higher education. Studying at a university requires a lot of reading, and if reading has not been taken up as a practice that involves more than ‘text consulting’ (Geisler, 1994) students will be unlikely to read the number of texts required of them. Studies (see Geisler, 1994 for an overview) have shown how the literacy of the university is very different to school based literacies. The assumption behind the study on which this thesis reports is that engagement with fictional texts might promote reading and bring about understandings of this activity as enjoyable and not a task only associated with schooling. The study is underpinned by a critical realist philosophy which allowed for the identification of structures and mechanisms that led to the emergence of literacy events in learners’ lives and to their experiences and observations of those events. The study was guided by the following questions: How do learners from a poorly-resourced high school engage around fictional texts in the context of a book club? What enables or constrains this engagement? The study was impacted by the Covid-19 pandemic in that lockdown requirements meant that learners from St Andrew’s College could not participate in the book club as much as anticipated initially as they had been forced to return home to pursue online learning. Learners from Nombuelo High School were, however, granted access to College premises, where they met in the school library following strict Covid protocols. The study draws on in-depth interviews, observations and document analysis of five learners from Nombulelo High School who participated in the book club, as well as on book reviews they wrote for the book club website. The critical realist analysis allows for the identification of mechanisms in learners’ homes and communities that enable literacies, including those that are screen-based such as using a computer, mobile phones and other technologies. This study found evidence of challenges regarding school based texts, reading fictional texts and viewing it as an enrichment of the school project. Because of children were African the emergence of communal practices and story telling is woven throughout the results section. However, is an example of the complexity of social and economic challenges facing South African marginalised schools. , Thesis (MEd) -- Faculty of Education, Centre for Higher Education Research, 2022
- Full Text:
- Date Issued: 2022-04-08
Self-inquiry: Comparing Plato and Patanjali
- Authors: Coughlan, Daniel Michael
- Date: 2021-10
- Subjects: Plato , Patañjali , Self , Identity (Philosophical concept) , Comparison (Philosophy) , Justification (Theory of knowledge)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190066 , vital:44960
- Description: At its most effective my research hopes to re-affirm the central value and importance of self-inquiry. That is, I hope to echo the familiar call of the wise to know thyself. Of the many mouths and temple walls that have lent authority to this precept there is perhaps no mouth more important than one’s own. To know thyself is the task and responsibility of the individual. In order to arrive at the point where I can re-affirm its value I explore the nature of self-inquiry with the help of Plato, Patanjali and a comparison between them. I propose two general senses in which we might understand self-inquiry and seek to bring out the core problems faced by each. We find an account of these two senses and the relationship between them in both Plato and Patanjali, so too, though less obviously, in the comparison between them. The comparison provides the opportunity for reflecting on the ground that it moves from and depends on, the common ground we assume between the two compared philosophers/ies. I contend that this ground is ultimately the comparer, one’s self. The consequence is that the comparative project and the project of self-inquiry both meet and are mutually beneficial. The three together; Plato, Patanjali, and the comparison between them help us account for nature of self-inquiry in helping us to better understand the relationship between the two senses in which we can come to understand and think about it. In the first sense, self-inquiry is cast as the examination of one’s life. In the second sense, we are invited to consider the possibility of an unmediated knowing of the examiner, an unmediated self-knowing. With a better understanding of what self-inquiry is I stand to conclude by re-affirming its value. , Thesis (MPhil) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Coughlan, Daniel Michael
- Date: 2021-10
- Subjects: Plato , Patañjali , Self , Identity (Philosophical concept) , Comparison (Philosophy) , Justification (Theory of knowledge)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190066 , vital:44960
- Description: At its most effective my research hopes to re-affirm the central value and importance of self-inquiry. That is, I hope to echo the familiar call of the wise to know thyself. Of the many mouths and temple walls that have lent authority to this precept there is perhaps no mouth more important than one’s own. To know thyself is the task and responsibility of the individual. In order to arrive at the point where I can re-affirm its value I explore the nature of self-inquiry with the help of Plato, Patanjali and a comparison between them. I propose two general senses in which we might understand self-inquiry and seek to bring out the core problems faced by each. We find an account of these two senses and the relationship between them in both Plato and Patanjali, so too, though less obviously, in the comparison between them. The comparison provides the opportunity for reflecting on the ground that it moves from and depends on, the common ground we assume between the two compared philosophers/ies. I contend that this ground is ultimately the comparer, one’s self. The consequence is that the comparative project and the project of self-inquiry both meet and are mutually beneficial. The three together; Plato, Patanjali, and the comparison between them help us account for nature of self-inquiry in helping us to better understand the relationship between the two senses in which we can come to understand and think about it. In the first sense, self-inquiry is cast as the examination of one’s life. In the second sense, we are invited to consider the possibility of an unmediated knowing of the examiner, an unmediated self-knowing. With a better understanding of what self-inquiry is I stand to conclude by re-affirming its value. , Thesis (MPhil) -- Faculty of Humanities, Philosophy, 2021
- Full Text:
- Date Issued: 2021-10
Investigation of sediment buffering function of the Gatberg Floodplain Wetland in the upper Tsitsa River Catchment, South Africa
- Pakati, Sibuyisele Sweetness
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Pakati, Sibuyisele Sweetness
- Date: 2021-10
- Subjects: Sedimentation and deposition South Africa Eastern Cape , Sediment transport South Africa Eastern Cape , Floodplain morphology South Africa Eastern Cape , Wetlands South Africa Eastern Cape , Suspended sediments South Africa Eastern Cape , Floods South Africa Eastern Cape , Fluvial geomorphology South Africa Eastern Cape , Floodplain plants South Africa Eastern Cape , Inundation depth
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190792 , vital:45028
- Description: Floodplain wetlands are important components of river systems that provide various ecosystem services such as sediment buffering. These wide and often expansive storage areas have a substantial impact on downstream water quality by trapping sediment and storing ‘contaminants’ adhered to sediment thus improving water quality. The planned construction of the Ntabelanga and Lalini Dams in the Tsitsa River Catchment has been proposed; however, due to the steep landscapes and erodible soils, this promotes high erosion rates that can potentially reduce the lifespan of the proposed dams. The existing wetlands in the Tsitsa River Catchment have therefore been identified as key sediment buffers that can reduce sediment transport, but the effectiveness of these buffers is poorly researched. This study attempts to investigate the current sediment buffering function of the Gatberg Floodplain Wetland over one wet season (August 2019 to August 2020). Time integrated samplers were installed above and below the wetland to determine relative sediment volume and character coming in and out of the wetland. Five transects were surveyed across the wetland width to evaluate the topography and vegetation characteristics. Surface sediment samples on the floodplain were taken at key morphological features along each transect and along the river longitudinal profile to determine organic content, particle size, and type of stored sediment. Astro turf mats were deployed on targeted transects and on key floodplain features to determine sediment accumulation rates. Field measurements of vegetation parameters (height, density, and stem diameter) were taken to calculate vegetation-induced hydraulic roughness to understand possible sedimentation feedbacks. The relative sediment volume coming into the wetland was greater than that leaving the wetland. This implies that some of the sediment is buffered within the wetland. An approximate proportion of 73% trapping efficiency of the incoming sediment was buffered within the floodplain wetland during the wet season. This accumulated approximately 4 tons within the wetland over the monitoring frame. Bed particle size in the longitudinal profile increased with distance downstream, this was due to localized tributary and hillslope inputs. Inundation depth varied across the floodplain wetland with deeper inundation depths at the head of the wetland than at the bottom; where particle size was larger with an increase in water level depth. This may be linked to both high stream velocities and variability of the floodplain topography. However, the observed trends were inconclusive and uncertain. Stronger correlations with particle size were shown by vegetation roughness (b* = 0.41) and distance from the channel (b* = -0.38). Flood benches and banks had a coarser D50 particle size than back swamps and oxbows. Coarser sediment in flood benches are associated with proximity to the sediment-laden water that experiences abrupt flow velocity changes, while finer material in oxbows are due to minimal flow velocities which reduce with distance from the channel. Finer particles remain in suspension and are carried aloft for longer periods at very low velocities. Therefore, particle size decreased with distance from the channel due to longer travel distances and high surface area relative to weight. Further results showed that finer surface sediment particle size was associated with high vegetation roughness whilst coarser material was associated with low roughness. This was due to vegetation geometry and type or changes in flow velocity and energy. Grassy vegetation induced finer particle size than shrubby vegetation that has a greater line spacing. Furthermore, vegetation roughness varied over the wet season; roughness was highest in late summer and low in early summer. Low roughness was due to fire occurrence in the study area which resulted in a decrease in biomass. Increasing vegetation roughness can be due to increased flood events, and the introduction of non-perennial species; which can increase sediment accumulation rates. Although studies have shown that vegetation density is the most essential factor affecting flow resistance and sedimentation processes; vegetation height and stem diameter for this study area seem to contrast these observations and rather may be the most significant contributing factors in sedimentation. This concluded that vegetation density may not always be the most essential component in sedimentation processes. Sediment particle size was inversely proportional to organic content; finer particle size are more cohesive and more capable of carrying organics. Regions further away from the channel such as oxbows with stable moisture conditions favour plant growth and soil formation thus are susceptible to high organic content. Flood benches are closer to the channel, thus have coarser material and fluctuating moisture conditions that have unstable high water flow velocities. High sediment accumulation rates on flood benches and oxbows is due to high connectivity to sediment-laden water and high hydroperiods or high residence time for sediment accumulation in oxbows. Sediment accumulation rate was shown to be a function of particle size itself (b* = 0.67) rather than the expected vegetation roughness. Although a true representation of sediment accumulation rates in the Gatberg Wetland was limited by the disturbance of astro turf mats by animals and possibly by high flooding events; the wetland can be regarded as a good sediment buffer as some sediment was stored (e.g. up to 48,04 kg/m2 in flood benches) within the wetland over the monitoring period. , Thesis (MSc) -- Faculty of Science, Geography, 2021
- Full Text:
- Date Issued: 2021-10
The Relationship between capital adequacy and profitability under Basel III in the Namibian banking sector
- Authors: Pomuti, Esther Kaulinawa
- Date: 2021-10-29
- Subjects: Banks and banking Namibia , Banks and banking, International Law and legislation , Bank capital Law and legislation Namibia , Rate of return Namibia , Basle Committee on Banking Supervision , Ratio analysis , Basel III (2010)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191909 , vital:45178
- Description: Globally, capital adequacy is one of the most central topics for both regulatory authorities and banks. It promotes stability and intends to reduce bank insolvency. It also represents the most important element of banks’ profitability (Profits are the first line of defense against losses from credit loss in a bank). After the collapse of Bretton Woods in 1973, many banks incurred large foreign currency losses, with Banks outside Germany having taken heavy losses on their unsettled trades with Herstatt Bank in Cologne, West Germany, when it collapsed in June 1974. This study empirically tests the relationship between changes in the capital adequacy ratio under Basel III and return on equity (ROE) of the Namibian banking sector and whether such relationships exist in the short run or long run. The study used panel quarterly data for a sample of three Namibian commercial banks from the year 1999 to 2019.It employed one panel unit root tests namely: Im, Pesaran and Shin W-stat (IPS). To test the existence of a long-run relationship (equilibrium) or effect between the dependent and independent variables, the study employed the Panel Co-integration methods using Pedroni and Kao (Engle-Granger based) tests. The study carried out the Hausman test to determine the best approach for analysis and determined the PMG approach to be the preferable model for analysis. Various diagnostic tests such as multicollinearity through the correlation analysis, autocorrelation, and heteroscedasticity and cross-sectional dependence tests were carried out to determine if the data set is well-modelled and if the results can be taken seriously. The study’s results under the PMG model showed that ROE and CAR have a positive significant relationship in the short run. A dummy variable to capture the connection between ROE and CAR before and after BASEL III shows that the relationship is positive and significant indicating that ROE increases more when there is capital regulation than when there is no capital regulation. The study also concluded that there is no long run relationship between CAR and ROE. Finally, the interaction effect between the dummy variable and CAR is negative but significant and thus indicating that the positive relationship does not persist post Basel III. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Pomuti, Esther Kaulinawa
- Date: 2021-10-29
- Subjects: Banks and banking Namibia , Banks and banking, International Law and legislation , Bank capital Law and legislation Namibia , Rate of return Namibia , Basle Committee on Banking Supervision , Ratio analysis , Basel III (2010)
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191909 , vital:45178
- Description: Globally, capital adequacy is one of the most central topics for both regulatory authorities and banks. It promotes stability and intends to reduce bank insolvency. It also represents the most important element of banks’ profitability (Profits are the first line of defense against losses from credit loss in a bank). After the collapse of Bretton Woods in 1973, many banks incurred large foreign currency losses, with Banks outside Germany having taken heavy losses on their unsettled trades with Herstatt Bank in Cologne, West Germany, when it collapsed in June 1974. This study empirically tests the relationship between changes in the capital adequacy ratio under Basel III and return on equity (ROE) of the Namibian banking sector and whether such relationships exist in the short run or long run. The study used panel quarterly data for a sample of three Namibian commercial banks from the year 1999 to 2019.It employed one panel unit root tests namely: Im, Pesaran and Shin W-stat (IPS). To test the existence of a long-run relationship (equilibrium) or effect between the dependent and independent variables, the study employed the Panel Co-integration methods using Pedroni and Kao (Engle-Granger based) tests. The study carried out the Hausman test to determine the best approach for analysis and determined the PMG approach to be the preferable model for analysis. Various diagnostic tests such as multicollinearity through the correlation analysis, autocorrelation, and heteroscedasticity and cross-sectional dependence tests were carried out to determine if the data set is well-modelled and if the results can be taken seriously. The study’s results under the PMG model showed that ROE and CAR have a positive significant relationship in the short run. A dummy variable to capture the connection between ROE and CAR before and after BASEL III shows that the relationship is positive and significant indicating that ROE increases more when there is capital regulation than when there is no capital regulation. The study also concluded that there is no long run relationship between CAR and ROE. Finally, the interaction effect between the dummy variable and CAR is negative but significant and thus indicating that the positive relationship does not persist post Basel III. , Thesis (MCom) -- Faculty of Commerce, Economics and Economic History, 2021
- Full Text:
- Date Issued: 2021-10-29
In a novel landscape, in the Eastern Cape, South Africa, what are the key vegetation resources that support livestock production?
- Liversage-Quinlan, William Peter
- Authors: Liversage-Quinlan, William Peter
- Date: 2021-10
- Subjects: Mzimvubu River Watershed (South Africa) , Livestock productivity South Africa Mzimvubu River Watershed , Range ecology South Africa Mzimvubu River Watershed , Land degradation South Africa Mzimvubu River Watershed , Vegetation dynamics South Africa Mzimvubu River Watershed , Novel landscapes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190053 , vital:44959
- Description: The Tsitsa River is the largest remaining river that is without a dam in South Africa, and so the government has pledged to install two major dams for irrigation and hydroelectricity, under the Mzimvubu Water Project. These dams are intended to supply water and electricity to surrounding communities as well as the large neighbouring urban areas of Mthatha and Tsolo. However, large areas of the Tsitsa Catchment (~494 000 ha) are degraded, posing the possibility that if these dams were to be created, they would inevitably fill with sediment and silt within a few decades. To address these issues, the Tsitsa Project was established in 2014 to co-ordinate actions by government, developers and local communities in order to restore the landscape condition and prevent soil erosion, as well as to improve the livelihoods of the people who live there (Fabricius, Biggs, & Powell, 2016). Research into the landscape condition as well and the environmental interactions with local communities are therefore highly necessary in order to guide restoration practices to their best effect. The economic necessity for livestock production in the catchment indicates its urgent need for a better understanding of its current effects on the catchment landscape and vegetation. The overall goal of this study is to contribute to the knowledge needed to manage the area in a sustainable way. This paper will therefore examine the key vegetation resources that support livestock production in an area of the Tsitsa River Catchment, by describing the various types that exist, and by determining their relative production levels of usable livestock forage. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Liversage-Quinlan, William Peter
- Date: 2021-10
- Subjects: Mzimvubu River Watershed (South Africa) , Livestock productivity South Africa Mzimvubu River Watershed , Range ecology South Africa Mzimvubu River Watershed , Land degradation South Africa Mzimvubu River Watershed , Vegetation dynamics South Africa Mzimvubu River Watershed , Novel landscapes
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190053 , vital:44959
- Description: The Tsitsa River is the largest remaining river that is without a dam in South Africa, and so the government has pledged to install two major dams for irrigation and hydroelectricity, under the Mzimvubu Water Project. These dams are intended to supply water and electricity to surrounding communities as well as the large neighbouring urban areas of Mthatha and Tsolo. However, large areas of the Tsitsa Catchment (~494 000 ha) are degraded, posing the possibility that if these dams were to be created, they would inevitably fill with sediment and silt within a few decades. To address these issues, the Tsitsa Project was established in 2014 to co-ordinate actions by government, developers and local communities in order to restore the landscape condition and prevent soil erosion, as well as to improve the livelihoods of the people who live there (Fabricius, Biggs, & Powell, 2016). Research into the landscape condition as well and the environmental interactions with local communities are therefore highly necessary in order to guide restoration practices to their best effect. The economic necessity for livestock production in the catchment indicates its urgent need for a better understanding of its current effects on the catchment landscape and vegetation. The overall goal of this study is to contribute to the knowledge needed to manage the area in a sustainable way. This paper will therefore examine the key vegetation resources that support livestock production in an area of the Tsitsa River Catchment, by describing the various types that exist, and by determining their relative production levels of usable livestock forage. , Thesis (MSc) -- Faculty of Science, Institute for Water Research, 2021
- Full Text:
- Date Issued: 2021-10
An evolutionary study of legless skinks’ (Acontias Cuvier, 1817) head and vertebrae morphology
- Authors: Evlambiou, Anthony Andreas
- Date: 2021-10
- Subjects: Skinks South Africa , Acontias South Africa , Typhlosaurus South Africa , Acontias Morphology , Acontias Phylogeny , Acontias Evolution , Vertebrae , Skull Growth , Evolutionary developmental biology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190690 , vital:45018
- Description: Environmental factors and/or processes can produce differences in general shape between individuals or particular parts of individuals. Examples of these biological processes may include ontogenetic development, adaptation to local geographic factors, or long-term evolutionary diversification. An organism is not likely to be able to optimise a single structure for multiple purposes and so trade-offs are likely to occur. An example of such a structure is the cranium, as it can be used for multiple activities such as defensive and sexual behaviour, locomotion, prey capture, and ingestion. Morphological characteristics have historically been used in the description of species. Genetic analyses have gained popularity as species delineation techniques and have been particularly useful in identifying cryptic species, especially among morphological conserved species like legless skinks of the subfamily Acontinae (e.g. Acontias Cuvier, 1817 and Typhlosaurus Weigmann, 1834). However, completely doing away with morphological techniques during species descriptions is not the best option. Therefore, novel methods to identify species, especially those with similar body plans, are needed. In this dissertation, we explore the links between head shape and vertebral number to environmental pressures to determine whether the evolutionary process is driven by environmental pressures (soil or biome) or is retained through ancestry. A novel species/clade delineation linked to vertebral number is also investigated. Head shape was expected to have a close link to the environment and the number of vertebrae was expected to have a closer link to ancestry. The first chapter investigates the drivers behind Acontias head shape evolution using geometric morphometric techniques. We found that environmental pressures did affect the evolution of head shape especially in the “soil” and “biome” categories but further investigation is advised. The second chapter explores the viability of using vertebral counts as a novel method for species and/or clade delineation in Acontias and to determine whether vertebral number can be linked to the environment. Delineating species based on vertebral count is likely not an option, however, delineating clades proved to show promising results. A link between vertebral count and environment was found in Acontias with larger bodied species occurring in different environments to smaller body species. In conclusion, the genus Acontias is difficult to delineate morphologically. Genetic sequence analyses can indicate differences and delineate the species. Even though there were differences in morphology based on environmental factors, it is not sufficient to delineate this subfamily alone. Further research is advised and this dissertation provides a good basis to work with. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Evlambiou, Anthony Andreas
- Date: 2021-10
- Subjects: Skinks South Africa , Acontias South Africa , Typhlosaurus South Africa , Acontias Morphology , Acontias Phylogeny , Acontias Evolution , Vertebrae , Skull Growth , Evolutionary developmental biology
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190690 , vital:45018
- Description: Environmental factors and/or processes can produce differences in general shape between individuals or particular parts of individuals. Examples of these biological processes may include ontogenetic development, adaptation to local geographic factors, or long-term evolutionary diversification. An organism is not likely to be able to optimise a single structure for multiple purposes and so trade-offs are likely to occur. An example of such a structure is the cranium, as it can be used for multiple activities such as defensive and sexual behaviour, locomotion, prey capture, and ingestion. Morphological characteristics have historically been used in the description of species. Genetic analyses have gained popularity as species delineation techniques and have been particularly useful in identifying cryptic species, especially among morphological conserved species like legless skinks of the subfamily Acontinae (e.g. Acontias Cuvier, 1817 and Typhlosaurus Weigmann, 1834). However, completely doing away with morphological techniques during species descriptions is not the best option. Therefore, novel methods to identify species, especially those with similar body plans, are needed. In this dissertation, we explore the links between head shape and vertebral number to environmental pressures to determine whether the evolutionary process is driven by environmental pressures (soil or biome) or is retained through ancestry. A novel species/clade delineation linked to vertebral number is also investigated. Head shape was expected to have a close link to the environment and the number of vertebrae was expected to have a closer link to ancestry. The first chapter investigates the drivers behind Acontias head shape evolution using geometric morphometric techniques. We found that environmental pressures did affect the evolution of head shape especially in the “soil” and “biome” categories but further investigation is advised. The second chapter explores the viability of using vertebral counts as a novel method for species and/or clade delineation in Acontias and to determine whether vertebral number can be linked to the environment. Delineating species based on vertebral count is likely not an option, however, delineating clades proved to show promising results. A link between vertebral count and environment was found in Acontias with larger bodied species occurring in different environments to smaller body species. In conclusion, the genus Acontias is difficult to delineate morphologically. Genetic sequence analyses can indicate differences and delineate the species. Even though there were differences in morphology based on environmental factors, it is not sufficient to delineate this subfamily alone. Further research is advised and this dissertation provides a good basis to work with. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
A sustainability practices educational intervention in response to environmental matters of concern amongst Makhanda youth
- Authors: Musiyiwa, Fungayi Lona
- Date: 2021-10-29
- Subjects: Sustainable living South Africa Makhanda , Social learning South Africa Makhanda , Eco clubs South Africa Makhanda , Environmental education Activity programs South Africa Makhanda , Youth in development South Africa Makhanda , Youth Social conditions
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/188364 , vital:44747
- Description: This study responded to urbanisation as one of the challenges affecting youths’ lifestyles in this century. Children and youth around the world are living in overpopulated, polluted and unsafe environments which fail to produce opportunities for learning, play and recreation (World Health Organisation [WHO], 2017). This study explored these issues in the context of Makhanda with an intervention to engage youth in sustainability practices, to help them to strengthen sustainable lifestyles. The participants in this research were members of two eco-clubs from two schools in Makhanda ranging in age from 12-14 years (primary school) and 15-17 years (high school). The study explored how learning processes within a club intervention contributed to the well- being of participating youth and their capacity to live sustainable and fulfilling lives. The research explored (with participants) eight themes as matters of concern namely, ‘education’, ‘home-life’, ‘energy use’, ‘mobility’, ‘leisure and communication’, ‘waste’, ‘water’ and ‘food’. Detailed case narratives exploring Wals’ social learning stages were used to explore the themes. These themes were explored through photo narratives of the youths’ lives and matters of concern in sustainability issues, risks and practices emanating from the Makhanda context. The pedagogical framework for the intervention was guided by Wals’ social learning framework for mobilizing sustainability practices. Social learning interaction took place through all the stages of the framework and the challenges and potentials of the educational intervention were explored in relation to each stage. From the six themes suggested above the youth chose food and water as themes to take forward as a response project. The project pursued was a vegetable garden in which the youth were actively engaged in order to seek and try out sustainable ways of living. An interpretive approach was used within the interpretive paradigm. Qualitative data were generated through focus group discussions, observations, individual interviews and document analysis. Practice architectures theory was used analytically to explore the dynamics of the emergent sustainability practices initiated by the eco-club youth. I used it as a change method and a tool for initiating social learning actions for ‘sustainability practices’ projects. The study indicated that the youth’s key challenges affecting sustainability of their lifestyles are: lack of access to basic infrastructure, recreational facilities, electricity supply, transport, security and water. In this study, it was clear that much of the youth’s involvement in these matters of concern and sustainability issues was at the level of participating in the six themes through Wals’ social learning processes. This allowed youths to develop their knowledge and skills on how to participate in the gardening project rather than simply focusing on the environmental matters of concern in question. The Handprint Resource Books have been designed for educators who are looking for practical ideas to work with in the learning areas of the National Curriculum. The focus is on sustainability practices that can be taken up within the perspective that each learning area brings to environment and sustainability concerns. The use of the Handprint Resource Books promoted active youth participation and interaction encouraging youth to be reflective thinkers, which led to understanding of the issues and the sustainability practices that emerged during the discussions. The Handprint Resource Books focused on sustainability practices within the learning area of environment and sustainability concerns. Due to her facilitation skills, an environmental expert’s presentation on a sustainability topic enabled youths to select the intended project. The involvement of youth in the implementation of the vegetable garden as a sustainability practice empowered youth to be more confident in engaging in a collective action for change as they developed the capability to share and start their own vegetable gardens at their homes. , Thesis (MEd) -- Faculty of Education, Environmental Learning Research Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
- Authors: Musiyiwa, Fungayi Lona
- Date: 2021-10-29
- Subjects: Sustainable living South Africa Makhanda , Social learning South Africa Makhanda , Eco clubs South Africa Makhanda , Environmental education Activity programs South Africa Makhanda , Youth in development South Africa Makhanda , Youth Social conditions
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/188364 , vital:44747
- Description: This study responded to urbanisation as one of the challenges affecting youths’ lifestyles in this century. Children and youth around the world are living in overpopulated, polluted and unsafe environments which fail to produce opportunities for learning, play and recreation (World Health Organisation [WHO], 2017). This study explored these issues in the context of Makhanda with an intervention to engage youth in sustainability practices, to help them to strengthen sustainable lifestyles. The participants in this research were members of two eco-clubs from two schools in Makhanda ranging in age from 12-14 years (primary school) and 15-17 years (high school). The study explored how learning processes within a club intervention contributed to the well- being of participating youth and their capacity to live sustainable and fulfilling lives. The research explored (with participants) eight themes as matters of concern namely, ‘education’, ‘home-life’, ‘energy use’, ‘mobility’, ‘leisure and communication’, ‘waste’, ‘water’ and ‘food’. Detailed case narratives exploring Wals’ social learning stages were used to explore the themes. These themes were explored through photo narratives of the youths’ lives and matters of concern in sustainability issues, risks and practices emanating from the Makhanda context. The pedagogical framework for the intervention was guided by Wals’ social learning framework for mobilizing sustainability practices. Social learning interaction took place through all the stages of the framework and the challenges and potentials of the educational intervention were explored in relation to each stage. From the six themes suggested above the youth chose food and water as themes to take forward as a response project. The project pursued was a vegetable garden in which the youth were actively engaged in order to seek and try out sustainable ways of living. An interpretive approach was used within the interpretive paradigm. Qualitative data were generated through focus group discussions, observations, individual interviews and document analysis. Practice architectures theory was used analytically to explore the dynamics of the emergent sustainability practices initiated by the eco-club youth. I used it as a change method and a tool for initiating social learning actions for ‘sustainability practices’ projects. The study indicated that the youth’s key challenges affecting sustainability of their lifestyles are: lack of access to basic infrastructure, recreational facilities, electricity supply, transport, security and water. In this study, it was clear that much of the youth’s involvement in these matters of concern and sustainability issues was at the level of participating in the six themes through Wals’ social learning processes. This allowed youths to develop their knowledge and skills on how to participate in the gardening project rather than simply focusing on the environmental matters of concern in question. The Handprint Resource Books have been designed for educators who are looking for practical ideas to work with in the learning areas of the National Curriculum. The focus is on sustainability practices that can be taken up within the perspective that each learning area brings to environment and sustainability concerns. The use of the Handprint Resource Books promoted active youth participation and interaction encouraging youth to be reflective thinkers, which led to understanding of the issues and the sustainability practices that emerged during the discussions. The Handprint Resource Books focused on sustainability practices within the learning area of environment and sustainability concerns. Due to her facilitation skills, an environmental expert’s presentation on a sustainability topic enabled youths to select the intended project. The involvement of youth in the implementation of the vegetable garden as a sustainability practice empowered youth to be more confident in engaging in a collective action for change as they developed the capability to share and start their own vegetable gardens at their homes. , Thesis (MEd) -- Faculty of Education, Environmental Learning Research Centre, 2021
- Full Text:
- Date Issued: 2021-10-29
The physical activity status and the impact of lifestyle behaviours on workplace productivity and absenteeism of Transnet employees
- Authors: Zimmermann, Sharnae Vanessa
- Date: 2021-10
- Subjects: Transnet (Firm : South Africa) Employees , Absenteeism (Labor) South Africa Durban , Labor productivity South Africa Durban , Exercise , Sedentary behavior , Lifestyles
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190077 , vital:44961
- Description: Increased sitting time, insufficient physical activity and sub-optimal body composition are all contributing to the global disease burden. This is made evident by increases in obesity, type II diabetes, cardiovascular diseases (i.e. hypertension and strokes), cancer and other non-communicable diseases resulting in absenteeism and reduced productivity in the workplace. The global rise in sitting time and physical inactivity is caused, in part, by changes in transport convenience, work roles and technological advancements. Employees working in office environments or driving trains sit for prolonged periods; something which is evident in the industry that Transnet operates in. Sitting time and physical inactivity are independent risk factors for non-communicable diseases with poor nutrition, smoking, alcohol consumption and psychological wellbeing, being separate constructs. The purpose of the study is to determine the levels of sedentary behaviour, physical inactivity, obesity, nutrition, alcohol consumption, smoking, non-communicable disease risk, mental wellbeing and their association with productivity and absenteeism in office workers and train drivers at Transnet Freight Rail, Durban. A cross-sectional study was done with 40 participants, 20 office workers and 20 train drivers. Stature (175.80 ± 9.43 ±cm) and body mass (83.85 ± 20.31 kg) were measured; and body mass index calculated (26.98 ± 5.37 kg.m2). Physical activity levels, sedentary behaviour, body mass index and other lifestyle factors were explored using an amended version of The Health and Wellbeing survey, a self-report measure. The results revealed that there was a high prevalence of sedentary behaviour (train drivers = 7.85 ± 2.21 and office workers = 8.3 ± 1.03), particularly among office workers. Most of the participants had a relatively high body mass index, placing in the overweight and obese category, particularly among train drivers. The prevalence of physical inactivity was marginally higher for office workers compared to train drivers. There were significantly (p<0.05) higher levels of physical activity within train drivers with a moderate effect size. There were limited associations found between lifestyle factors and sickness absenteeism and worker productivity. Obesity had the most prominent relationship with noncommunicable diseases, followed by high levels of sedentary behaviour, not meeting physical activity guidelines, obesity, overweight, and prolonged sitting time at work. A significant and moderate correlation was found between obesity and absenteeism (train drivers: r = 0.32 and office workers: r= 0.46), however, no associations were found between sedentary behaviour, physical activity and fruit and vegetable intake and absenteeism. Lastly, the association between physical activity and productivity among the train drivers was low negative (r=-0.15) which was not significant (p>0.05). The associations between physical activity and productivity among office workers, however, was both significant (p<0.05) and moderate positive (r=0.39). The vegetable intake among the office workers showed a significant (p<0.05) moderate positive association with productivity (r=0.49). The association between vegetable intake and productivity among the train drivers was not significant (p>0.05) and low positive (r=0.16). There was a significant (p<0.05) and moderate positive association between fruit intake and productivity among both train drivers (r=0.43) and office workers (r=0.47). No significant associations between sedentary behaviour and obesity and productivity were found. The current study provided new insight into the risks associated with lifestyle factors of office workers and train drivers in the transportation sector. The poor lifestyle factors, together with the high prevalence of sedentary behaviour and physical inactivity, provide ideal opportunities for future interventions to focus on workers productivity and overall wellbeing. The job design of train drivers and office workers does not place significant importance on employee health and wellness. Essentially they are not “healthy” but they work productively, giving reason as to why employee wellness is not a priority for employers. The current findings of the study suggest that adopting regular physical activity, healthy dietary patterns and reduced sitting time should be promoted as key components of lifestyle interventions for the prevention of non-communicable diseases in office workers and train drivers. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Zimmermann, Sharnae Vanessa
- Date: 2021-10
- Subjects: Transnet (Firm : South Africa) Employees , Absenteeism (Labor) South Africa Durban , Labor productivity South Africa Durban , Exercise , Sedentary behavior , Lifestyles
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190077 , vital:44961
- Description: Increased sitting time, insufficient physical activity and sub-optimal body composition are all contributing to the global disease burden. This is made evident by increases in obesity, type II diabetes, cardiovascular diseases (i.e. hypertension and strokes), cancer and other non-communicable diseases resulting in absenteeism and reduced productivity in the workplace. The global rise in sitting time and physical inactivity is caused, in part, by changes in transport convenience, work roles and technological advancements. Employees working in office environments or driving trains sit for prolonged periods; something which is evident in the industry that Transnet operates in. Sitting time and physical inactivity are independent risk factors for non-communicable diseases with poor nutrition, smoking, alcohol consumption and psychological wellbeing, being separate constructs. The purpose of the study is to determine the levels of sedentary behaviour, physical inactivity, obesity, nutrition, alcohol consumption, smoking, non-communicable disease risk, mental wellbeing and their association with productivity and absenteeism in office workers and train drivers at Transnet Freight Rail, Durban. A cross-sectional study was done with 40 participants, 20 office workers and 20 train drivers. Stature (175.80 ± 9.43 ±cm) and body mass (83.85 ± 20.31 kg) were measured; and body mass index calculated (26.98 ± 5.37 kg.m2). Physical activity levels, sedentary behaviour, body mass index and other lifestyle factors were explored using an amended version of The Health and Wellbeing survey, a self-report measure. The results revealed that there was a high prevalence of sedentary behaviour (train drivers = 7.85 ± 2.21 and office workers = 8.3 ± 1.03), particularly among office workers. Most of the participants had a relatively high body mass index, placing in the overweight and obese category, particularly among train drivers. The prevalence of physical inactivity was marginally higher for office workers compared to train drivers. There were significantly (p<0.05) higher levels of physical activity within train drivers with a moderate effect size. There were limited associations found between lifestyle factors and sickness absenteeism and worker productivity. Obesity had the most prominent relationship with noncommunicable diseases, followed by high levels of sedentary behaviour, not meeting physical activity guidelines, obesity, overweight, and prolonged sitting time at work. A significant and moderate correlation was found between obesity and absenteeism (train drivers: r = 0.32 and office workers: r= 0.46), however, no associations were found between sedentary behaviour, physical activity and fruit and vegetable intake and absenteeism. Lastly, the association between physical activity and productivity among the train drivers was low negative (r=-0.15) which was not significant (p>0.05). The associations between physical activity and productivity among office workers, however, was both significant (p<0.05) and moderate positive (r=0.39). The vegetable intake among the office workers showed a significant (p<0.05) moderate positive association with productivity (r=0.49). The association between vegetable intake and productivity among the train drivers was not significant (p>0.05) and low positive (r=0.16). There was a significant (p<0.05) and moderate positive association between fruit intake and productivity among both train drivers (r=0.43) and office workers (r=0.47). No significant associations between sedentary behaviour and obesity and productivity were found. The current study provided new insight into the risks associated with lifestyle factors of office workers and train drivers in the transportation sector. The poor lifestyle factors, together with the high prevalence of sedentary behaviour and physical inactivity, provide ideal opportunities for future interventions to focus on workers productivity and overall wellbeing. The job design of train drivers and office workers does not place significant importance on employee health and wellness. Essentially they are not “healthy” but they work productively, giving reason as to why employee wellness is not a priority for employers. The current findings of the study suggest that adopting regular physical activity, healthy dietary patterns and reduced sitting time should be promoted as key components of lifestyle interventions for the prevention of non-communicable diseases in office workers and train drivers. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2021
- Full Text:
- Date Issued: 2021-10
Modification of Gelatin-Methacrylate, Hyaluronic-Methacrylate and Poly(ethylene) glycol Diacrylate hydrogel bioinks towards the additive manufacturing of articular cartilage
- Authors: Barwick, Matthew William
- Date: 2021-10
- Subjects: Cartilage Diseases , Cartilage Regeneration , Articular cartilage Diseases , Chondrogenesis , Stem cells , Scanning electron microscopy , Fourier transform infrared spectroscopy , Three-dimensional printing , Gelatin-Methacrylate , Hyaluronic-Methacrylate , Poly(ethylene) glycolDiacrylate , Hydrogel bioinks , Real-Time Quantitative Cell Analysis (RTCA) , Bioprinting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191181 , vital:45068
- Description: Cartilage degradation is most commonly associated with Rheumatoid arthritis and Osteoarthritis, affecting millions of people worldwide. Joint transplants commonly use titanium alloys, which have a shelf life of between 10-15 years. Although the titanium transplant restores partial mobility, side effects such as inflammation, swelling, faulty implants, and metal poisoning in some cases resulting from the transplant. The use of additive manufacturing of articular cartilage sheds new, innovative prospects for joint replacements. This study sets out to formulate and characterize five different hydrogel types towards the additive manufacturing of articular cartilage. Chondrogenic and Adipogenic differentiation was carried out on two separate adipose-mesenchymal stem cell lines A270620-01A, and A311019-02T and validation and efficiency of the differentiation and chondrogenic gene expression was carried out using Alcian Blue stain, Oil Red O stain and Quantitative Reverse Transcription PCR (RT-qPCR). Hydrogel formulation and characterisation of 10 % Gelatin-methacryloyl (GelMA), 10 % Poly (ethylene) glycol diacrylate (PEGDA), 5 % GelMA/5 % PEGDA, 10 % GelMA/0.5 % Hyaluronic Acid Methacrylate (HAMA) and 10 % PEGDA/0.5 % HAMA was carried out through swelling and degradation ratios, surface area and porosity characterisation using Scanning Electron Microscopy (SEM). Hydrogel component and spectroscopic analysis were carried using Real-Time Quantitative Cell Analysis (RTCA) and Fourier-transform Infrared Spectroscopy (FTIR) analysis for each formulated hydrogel's chemical characterisation. Three-dimensional printing (3D) of 10 % PEGDA/0.5 % HAMA and 5 % GelMA/5 % PEGDA was performed using the Zortrax INKSPIRE Resin Ultra-Violet (UV) LCD Desktop 3D Printer. Hydrogel sterility and cell viability were carried out for each hydrogel type using fluorescence microscopy. Both A270620-01A and A311019-02T cell lines showed adipogenic and chondrogenic differentiation ability, with A311019-02T cell line showing greater chondrogenic differentiation of Alcian blue staining. The A270620-01A cell line resulted in a greater collagen gene expression based on the RT-qPCR results. The hydrogel 10 % GelMA showed the greatest swelling ratio of 1260 % in DPBS and 1192 % in DMEM. A significant difference between hydrogel swelling and swelling with Dulbecco's Phosphate Buffered Saline (DPBS) and Dulbecco’s Modified Eagle Medium (DMEM) was observed. The 10 % PEGDA hydrogel had the greatest degradation ratio of 59 % mass remaining, where the 10 % GelMA/0.5 % HAMA showed the least amount of degradation with a mass remaining at 91 %. The 10 % GelMA showed the greatest porosity will the largest pore size of 14 μm in diameter. Hydrogel component and spectroscopic analysis showed no cytotoxic effects for the visible light photoinitiator used to polymerize the hydrogel and no cytotoxic effects for the concentrations used in chondrogenic differentiation. The FTIR analysis showed partial gelatin and hyaluronic acid modification with methacrylic anhydride; however, the distinction between the hybrid hydrogels and single polymer hydrogels could not be made effectively. UV and ethanol washing showed to completely sterilise the hydrogel disks from any contaminants, making them suitable for tissue culture. The cell viability analysis showed the 10 % GelMA/HAMA having the highest cell viability of 77.3 % using 5000 cells/disk and 89.64 % viability using 50 000 cells/disk over a 7-day incubation period. Overall, the combination of two polymers, GelMA and HAMA, has good potential as a 3D hydrogel scaffold towards additive manufacturing of articular cartilage. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Barwick, Matthew William
- Date: 2021-10
- Subjects: Cartilage Diseases , Cartilage Regeneration , Articular cartilage Diseases , Chondrogenesis , Stem cells , Scanning electron microscopy , Fourier transform infrared spectroscopy , Three-dimensional printing , Gelatin-Methacrylate , Hyaluronic-Methacrylate , Poly(ethylene) glycolDiacrylate , Hydrogel bioinks , Real-Time Quantitative Cell Analysis (RTCA) , Bioprinting
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/191181 , vital:45068
- Description: Cartilage degradation is most commonly associated with Rheumatoid arthritis and Osteoarthritis, affecting millions of people worldwide. Joint transplants commonly use titanium alloys, which have a shelf life of between 10-15 years. Although the titanium transplant restores partial mobility, side effects such as inflammation, swelling, faulty implants, and metal poisoning in some cases resulting from the transplant. The use of additive manufacturing of articular cartilage sheds new, innovative prospects for joint replacements. This study sets out to formulate and characterize five different hydrogel types towards the additive manufacturing of articular cartilage. Chondrogenic and Adipogenic differentiation was carried out on two separate adipose-mesenchymal stem cell lines A270620-01A, and A311019-02T and validation and efficiency of the differentiation and chondrogenic gene expression was carried out using Alcian Blue stain, Oil Red O stain and Quantitative Reverse Transcription PCR (RT-qPCR). Hydrogel formulation and characterisation of 10 % Gelatin-methacryloyl (GelMA), 10 % Poly (ethylene) glycol diacrylate (PEGDA), 5 % GelMA/5 % PEGDA, 10 % GelMA/0.5 % Hyaluronic Acid Methacrylate (HAMA) and 10 % PEGDA/0.5 % HAMA was carried out through swelling and degradation ratios, surface area and porosity characterisation using Scanning Electron Microscopy (SEM). Hydrogel component and spectroscopic analysis were carried using Real-Time Quantitative Cell Analysis (RTCA) and Fourier-transform Infrared Spectroscopy (FTIR) analysis for each formulated hydrogel's chemical characterisation. Three-dimensional printing (3D) of 10 % PEGDA/0.5 % HAMA and 5 % GelMA/5 % PEGDA was performed using the Zortrax INKSPIRE Resin Ultra-Violet (UV) LCD Desktop 3D Printer. Hydrogel sterility and cell viability were carried out for each hydrogel type using fluorescence microscopy. Both A270620-01A and A311019-02T cell lines showed adipogenic and chondrogenic differentiation ability, with A311019-02T cell line showing greater chondrogenic differentiation of Alcian blue staining. The A270620-01A cell line resulted in a greater collagen gene expression based on the RT-qPCR results. The hydrogel 10 % GelMA showed the greatest swelling ratio of 1260 % in DPBS and 1192 % in DMEM. A significant difference between hydrogel swelling and swelling with Dulbecco's Phosphate Buffered Saline (DPBS) and Dulbecco’s Modified Eagle Medium (DMEM) was observed. The 10 % PEGDA hydrogel had the greatest degradation ratio of 59 % mass remaining, where the 10 % GelMA/0.5 % HAMA showed the least amount of degradation with a mass remaining at 91 %. The 10 % GelMA showed the greatest porosity will the largest pore size of 14 μm in diameter. Hydrogel component and spectroscopic analysis showed no cytotoxic effects for the visible light photoinitiator used to polymerize the hydrogel and no cytotoxic effects for the concentrations used in chondrogenic differentiation. The FTIR analysis showed partial gelatin and hyaluronic acid modification with methacrylic anhydride; however, the distinction between the hybrid hydrogels and single polymer hydrogels could not be made effectively. UV and ethanol washing showed to completely sterilise the hydrogel disks from any contaminants, making them suitable for tissue culture. The cell viability analysis showed the 10 % GelMA/HAMA having the highest cell viability of 77.3 % using 5000 cells/disk and 89.64 % viability using 50 000 cells/disk over a 7-day incubation period. Overall, the combination of two polymers, GelMA and HAMA, has good potential as a 3D hydrogel scaffold towards additive manufacturing of articular cartilage. , Thesis (MSc) -- Faculty of Science, Biotechnology Innovation Centre, 2021
- Full Text:
- Date Issued: 2021-10
The tuber-feeding weevil Listronotus frontalis as a candidate biological control agent for the invasive semi-aquatic plant Sagittaria platyphylla within South Africa
- Authors: Rogers, Daniel James
- Date: 2021-10
- Subjects: Listronotus South Africa , Arrowhead (Plants) South Africa , Arrowhead (Plants) Biological control South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Plant populations South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190731 , vital:45023
- Description: Sagittaria platyphylla (Engelm.) J.G.Sm. (Alismataceae) is an invasive, aquatic macrophyte originating in the southern United States of America. In South Africa, the plant was first detected in Krantzkloof Nature Reserve, KwaZulu-Natal Province in 2008, and due to its known impact in other countries, it was listed as a Category 1a invader species under the National Environmental Management: Biodiversity Act 2004 (NEM:BA). This invasive plant has proved difficult to manage due to its varied growth forms and reproductive strategies, such as prolific seed and below ground tuber production. Due to the limitations of conventional control mechanisms, biological control is currently being considered as a potential control option. The tuber feeding weevil Listronotus frontalis LeConte (Coleoptera: Curculionidae) has been identified as a candidate biological control agent for this invasive species. The aims of this study were twofold; to firstly determine the importance of tubers to S. platyphylla populations growing in South Africa; and secondly, to determine the biology and suitability of L. frontalis, a tuber feeder, as a candidate biological control agent. Surveys of S. platyphylla populations in South Africa showed that tubers were found in all sampled sites, except for Krantzkloof Nature reserve in KwaZulu-Natal Province. The highest number of tubers was 97.75 ± 10.62 (SE) m-2 recorded at Jonkershoek in the Western Cape Province. Monthly sampling from two sites in the Eastern Cape Province, the Makana Botanical Gardens and Maden Dam showed that neither season nor water depth affected tuber production. However, the mean number of tubers as well as mass of tubers sampled, were consistently higher (F(1,179) = 20.9542, P < 0.0001) and heavier (F(1, 857) = 585.7293, P < 0.0001) at the Botanical Gardens than at Maden Dam, respectively. The study showed that tubers are an important life stage of S. platyphylla populations and may vary in size and abundance between and within sites. The tuber feeding weevil was shown to develop from egg to ovipositing adult within just over 40 days. Females were recorded to lay up to 48 eggs within a period of one week. Impact studies showed that adult feeding led to a reduction in all but one of the 11 measured plant growth and developmental measurements, including a reduction in the mean mass of the above-ground plant material (F(2,2743) = 12.05, P = 0.002) as well as a reduction in size and abundance of tubers (F(2,58.47) = 9.756, P = 0.0006) and stolons(F(14.943) = 8.7577, P = 0.003). These results are encouraging and suggest that if the insect is released in South Africa, it may prove to be a valuable biocontrol agent. It is concluded that, until suitable biological control options become available in South Africa, the chemical and mechanical control measures currently implemented should continue, however, controlling tubers should be considered during the planning and implementation of these strategies. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10
- Authors: Rogers, Daniel James
- Date: 2021-10
- Subjects: Listronotus South Africa , Arrowhead (Plants) South Africa , Arrowhead (Plants) Biological control South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Plant populations South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10962/190731 , vital:45023
- Description: Sagittaria platyphylla (Engelm.) J.G.Sm. (Alismataceae) is an invasive, aquatic macrophyte originating in the southern United States of America. In South Africa, the plant was first detected in Krantzkloof Nature Reserve, KwaZulu-Natal Province in 2008, and due to its known impact in other countries, it was listed as a Category 1a invader species under the National Environmental Management: Biodiversity Act 2004 (NEM:BA). This invasive plant has proved difficult to manage due to its varied growth forms and reproductive strategies, such as prolific seed and below ground tuber production. Due to the limitations of conventional control mechanisms, biological control is currently being considered as a potential control option. The tuber feeding weevil Listronotus frontalis LeConte (Coleoptera: Curculionidae) has been identified as a candidate biological control agent for this invasive species. The aims of this study were twofold; to firstly determine the importance of tubers to S. platyphylla populations growing in South Africa; and secondly, to determine the biology and suitability of L. frontalis, a tuber feeder, as a candidate biological control agent. Surveys of S. platyphylla populations in South Africa showed that tubers were found in all sampled sites, except for Krantzkloof Nature reserve in KwaZulu-Natal Province. The highest number of tubers was 97.75 ± 10.62 (SE) m-2 recorded at Jonkershoek in the Western Cape Province. Monthly sampling from two sites in the Eastern Cape Province, the Makana Botanical Gardens and Maden Dam showed that neither season nor water depth affected tuber production. However, the mean number of tubers as well as mass of tubers sampled, were consistently higher (F(1,179) = 20.9542, P < 0.0001) and heavier (F(1, 857) = 585.7293, P < 0.0001) at the Botanical Gardens than at Maden Dam, respectively. The study showed that tubers are an important life stage of S. platyphylla populations and may vary in size and abundance between and within sites. The tuber feeding weevil was shown to develop from egg to ovipositing adult within just over 40 days. Females were recorded to lay up to 48 eggs within a period of one week. Impact studies showed that adult feeding led to a reduction in all but one of the 11 measured plant growth and developmental measurements, including a reduction in the mean mass of the above-ground plant material (F(2,2743) = 12.05, P = 0.002) as well as a reduction in size and abundance of tubers (F(2,58.47) = 9.756, P = 0.0006) and stolons(F(14.943) = 8.7577, P = 0.003). These results are encouraging and suggest that if the insect is released in South Africa, it may prove to be a valuable biocontrol agent. It is concluded that, until suitable biological control options become available in South Africa, the chemical and mechanical control measures currently implemented should continue, however, controlling tubers should be considered during the planning and implementation of these strategies. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2021
- Full Text:
- Date Issued: 2021-10