Information and propaganda in the federation of Rhodesia and Nyasaland with special reference to print and radio propaganda for Africans, 1953-1963
- Authors: Zimudzi, Tapiwa Brown
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6957 , vital:21204
- Description: This thesis contributes to the history of the information and propaganda policy and practice of the government of the Federation of Rhodesia and Nyasaland by examining this government's pro-Federation print and radio propaganda for Africans in the Federation. Using a multi-theoretical approach, it analyses the character of this propaganda, highlighting its main methods and themes as well as the policy considerations, plus political and economic circumstances that gave rise to it. It also discusses how Africans in the Federation reacted to this propaganda and assesses its effectiveness in gaining the support of these Africans for Federation and the policies of the Federal government. The thesis argues that Federal government propaganda aimed at gaining the support of Africans for Federation was predominantly panic-driven propaganda and was the product of an information panic that lay at the heart of the very idea of Federation itself. This information panic arose out of the Federal government's belated recognition of the strength of African opposition to Federation and of how this opposition seriously threatened the continued survival of the Federation. It is also argued that this panic-driven pro-Federation propaganda elicited largely hostile reactions from the majority of Africans in the Federation and failed to persuade them to support Federation.
- Full Text:
- Authors: Zimudzi, Tapiwa Brown
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6957 , vital:21204
- Description: This thesis contributes to the history of the information and propaganda policy and practice of the government of the Federation of Rhodesia and Nyasaland by examining this government's pro-Federation print and radio propaganda for Africans in the Federation. Using a multi-theoretical approach, it analyses the character of this propaganda, highlighting its main methods and themes as well as the policy considerations, plus political and economic circumstances that gave rise to it. It also discusses how Africans in the Federation reacted to this propaganda and assesses its effectiveness in gaining the support of these Africans for Federation and the policies of the Federal government. The thesis argues that Federal government propaganda aimed at gaining the support of Africans for Federation was predominantly panic-driven propaganda and was the product of an information panic that lay at the heart of the very idea of Federation itself. This information panic arose out of the Federal government's belated recognition of the strength of African opposition to Federation and of how this opposition seriously threatened the continued survival of the Federation. It is also argued that this panic-driven pro-Federation propaganda elicited largely hostile reactions from the majority of Africans in the Federation and failed to persuade them to support Federation.
- Full Text:
The emergence and expression of teachers’ identities in teaching foundation phase mathematics
- Authors: Westaway, Lise
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7000 , vital:21208
- Description: The assertion that learner performance in South African schools is in crisis may be cliched but it is certainly true. The majority of learners in the schooling system are not achieving the required outcomes, particularly in language and mathematics. I use the underperformance of learners in mathematics as the impetus for my research which seeks to understand how teachers’ identities emerge and are expressed in teaching Foundation Phase mathematics. The research contributes to an emerging scholarship that strives to explain underperformance and quality in mathematics classrooms beyond structuralist theorising. Recently research, particularly in South Africa, has begun to look more closely at who the teacher is and how the teacher is key in understanding what happens in the mathematics classroom. This emerging scholarship focuses on teacher identities. Research that foregrounds teacher identities within the field of mathematics education tends to be situated within a social constructionist orientation, which assumes that our knowledge of self and the world comes from our interactions with people and not some ‘objective’ reality (Berger & Luckman, 1966). Such a perspective appears to conflate questions of how we know something with what is. In other words, it elides structure and agency, thereby making research that seeks to examine the interplay between the two in the formation and expression of teachers’ identities, practically impossible. It is for this reason, as well as the need to move beyond the hermeneutic, that my research draws on Margaret Archer’s (1995, 1996, 2000) social realist framework. Social realism posits a relativist epistemology but a realist ontology. It is underpinned by the notion of a stratified reality with structural mechanisms giving rise to events in the world whether we experience them or not. It is only through the (inter)actions of persons that such mechanisms have the tendential power to constrain or enable the projects of persons. As such, my research seeks to identify the structural and agential mechanisms that give rise to teachers’ identities and how these identities are expressed in teaching Foundation Phase mathematics. In my research, teacher identity refers to the manner in which teachers express their social roles as teachers. In the research I use a case study methodology. I provide rich data on four isiXhosa teachers teaching in low socio-economic status schools. This data is gleaned through interviews and classroom based observations which were recorded as field notes and video transcripts. Analysis of the data occurs through the thought processes of abduction and retroduction (Danermark, Ekstrom, Jakobsen, & Karlsson, 2002). These thought process enable me to (re)describe and (re)contextualise the object of study. Through the process of asking transfactual questions I identify the structural, cultural and agential mechanisms giving rise to teachers’ identities and their expression in teaching foundation phase mathematics. There are three significant findings in my research. Firstly, research that attempts to understand the emergence and expression of teacher identities should consider their broad contextual realities. The historical, economic, social and political contexts in which the teachers are born and live, influences their sense of self, personal identities and social identities (teacher identities) and as such, influences their decision to become teachers and how they express their roles as teachers of Foundation Phase mathematics. Secondly, my research suggests that teachers’ mode of reflexivity is key to understanding the decisions that they make in the classroom and how they deal with the structures that condition the manner in which they express their roles as teachers. Thirdly, collective agency is necessary to bring about change in the way in which teachers express their roles in teaching Foundation Phase mathematics. My research produces new knowledge by examining the interplay of structure, culture and agency in the constitution of foundation phase teachers’ identities and their expression in teaching foundation phase mathematics. I use a social realist orientation to examine this interplay and provide an understanding of the mechanisms giving rise to the phenomenon under consideration. In this way I contribute to the extensive research on learner underperformance by focusing more explicitly on who the teacher is in the classroom.
- Full Text:
- Authors: Westaway, Lise
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7000 , vital:21208
- Description: The assertion that learner performance in South African schools is in crisis may be cliched but it is certainly true. The majority of learners in the schooling system are not achieving the required outcomes, particularly in language and mathematics. I use the underperformance of learners in mathematics as the impetus for my research which seeks to understand how teachers’ identities emerge and are expressed in teaching Foundation Phase mathematics. The research contributes to an emerging scholarship that strives to explain underperformance and quality in mathematics classrooms beyond structuralist theorising. Recently research, particularly in South Africa, has begun to look more closely at who the teacher is and how the teacher is key in understanding what happens in the mathematics classroom. This emerging scholarship focuses on teacher identities. Research that foregrounds teacher identities within the field of mathematics education tends to be situated within a social constructionist orientation, which assumes that our knowledge of self and the world comes from our interactions with people and not some ‘objective’ reality (Berger & Luckman, 1966). Such a perspective appears to conflate questions of how we know something with what is. In other words, it elides structure and agency, thereby making research that seeks to examine the interplay between the two in the formation and expression of teachers’ identities, practically impossible. It is for this reason, as well as the need to move beyond the hermeneutic, that my research draws on Margaret Archer’s (1995, 1996, 2000) social realist framework. Social realism posits a relativist epistemology but a realist ontology. It is underpinned by the notion of a stratified reality with structural mechanisms giving rise to events in the world whether we experience them or not. It is only through the (inter)actions of persons that such mechanisms have the tendential power to constrain or enable the projects of persons. As such, my research seeks to identify the structural and agential mechanisms that give rise to teachers’ identities and how these identities are expressed in teaching Foundation Phase mathematics. In my research, teacher identity refers to the manner in which teachers express their social roles as teachers. In the research I use a case study methodology. I provide rich data on four isiXhosa teachers teaching in low socio-economic status schools. This data is gleaned through interviews and classroom based observations which were recorded as field notes and video transcripts. Analysis of the data occurs through the thought processes of abduction and retroduction (Danermark, Ekstrom, Jakobsen, & Karlsson, 2002). These thought process enable me to (re)describe and (re)contextualise the object of study. Through the process of asking transfactual questions I identify the structural, cultural and agential mechanisms giving rise to teachers’ identities and their expression in teaching foundation phase mathematics. There are three significant findings in my research. Firstly, research that attempts to understand the emergence and expression of teacher identities should consider their broad contextual realities. The historical, economic, social and political contexts in which the teachers are born and live, influences their sense of self, personal identities and social identities (teacher identities) and as such, influences their decision to become teachers and how they express their roles as teachers of Foundation Phase mathematics. Secondly, my research suggests that teachers’ mode of reflexivity is key to understanding the decisions that they make in the classroom and how they deal with the structures that condition the manner in which they express their roles as teachers. Thirdly, collective agency is necessary to bring about change in the way in which teachers express their roles in teaching Foundation Phase mathematics. My research produces new knowledge by examining the interplay of structure, culture and agency in the constitution of foundation phase teachers’ identities and their expression in teaching foundation phase mathematics. I use a social realist orientation to examine this interplay and provide an understanding of the mechanisms giving rise to the phenomenon under consideration. In this way I contribute to the extensive research on learner underperformance by focusing more explicitly on who the teacher is in the classroom.
- Full Text:
Biotic and abiotic factors promoting the development and proliferation of water hyacinth (eichhornia crassipes (Mart.) Solms-Laub.) in the Wouri Basin (Douala-Cameroon) and environs, with implications for its control
- Voukeng, Sonia Nadege Kenfack
- Authors: Voukeng, Sonia Nadege Kenfack
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7644 , vital:21281
- Description: The Wouri River, situated in the Wouri Basin, is one of the main rivers of the Littoral Region in the city of Douala in Cameroon. It is a source of income and food for the population living around these areas. Since the 1990s, the fishing, transportation, irrigation and sand extraction activities have been impeded by the invasion of aquatic plants, specifically water hyacinth (Eichhornia crassipes [Mart.] Solms-Laubach: Pontederiaceae). Introduced in 1997 to the shore of Lake Chad, water hyacinth has invaded almost 114 ha of the Wouri Basin. Furthermore, Douala, the economic capital of the Cameroon and location for more than 70% of the country’s industries, uses the Wouri River and its tributaries to deposit its effluent and waste, which has worsened the problem of water hyacinth. This thesis examined the ecological and socio-economic impacts of water hyacinth in the Wouri Basin and its possible control. An increase in the nutrients in the water has provided water hyacinth with appropriate conditions for its fast growth during both the rainy and dry seasons. The availability of nutrients in these areas is enhanced by the constant, daily tidal fluctuation of water, providing enough water to the plant for easy nutrient uptake. A survey of the impacts of water hyacinth on aquatic plant communities in the Wouri Basin showed that this plant is able to out-compete native species. Assessment of the impact of water hyacinth on the abundance and diversity of plant communities indicated that at some invaded sites, 65% of the vegetation consisted of water hyacinth. Species found in association with water hyacinth with a high level of abundance-dominance were Pistia stratiotes L. (Araceae) (another invader), Commelina benghalensis L. (Commelinaceae) and Echinochloa pyramidalis (Lam.) Hitchc. & Chase (Poaceae). This component of the study also showed that habitats rich in water hyacinth were poor in diversity, while habitats without water hyacinth were rich in diversity, thus raising awareness of the importance of monitoring invasive aquatic weeds along the Wouri Basin, and of implementing correct control management of all invasive aquatic weeds. Communities living along the invaded rivers are well aware of the range of problems caused by the weed; because as the rivers and water bodies used for fishing, transportation, and sand extraction are progressively invaded by the weed, the riparian population is the first to feel the impact. The impact on people has been noticeable, with an increase in diseases, such as malaria, cholera, diarrhoea, typhoid, filariasis, schistosomiasis, scabies and yellow fever increasing the need for a medicine and hospitalization. Economic losses due to the management of invasive aquatic weeds were recorded, and the Ministry of Environment spent an estimated US$1 200 000 between 2010 and 2015 to manage this scourge. In 2016, an amount of US$160 000 was transferred to these regions to manage invasive aquatic weeds, especially water hyacinth, although manual clearing is still the only method used to control this weed. Isolation of fungi from diseased water hyacinth plants in the Wouri Basin revealed several fungal species, most of which have been isolated from water hyacinth species in water bodies elsewhere, which showed a higher diversity during the dry season than during the rainy season. These fungi included Acremonium zonatum (Sawada). W. Gams (Hypocreaceae), Alternaria eichhorniae Nag Raj & Ponnappa (Pleosporaceae), Chaetomium sp., Colletotrichum sp., Curvularia pallescens Boedjin (Pleosporaceae), Curvalaria sp., Epicoccum nigrum Link (Pleosporaceae), Fusarium sp., Pithomyces chartarum fBerk. & M. A. Curtis) M. B. Ellis (Montagnulaceae), to a lesser extent Myrothecium roridum Tode ex Fr. (Incertae sedis) and Nigrospora sp. Although never released in Cameroon, arthropod biological control agents (Neochetina eichhorniae Warner (Coleoptera, Curculionidae) and N. bruchi Hustache (Coleoptera, Curculionidae)) were present, but their populations were relatively low. The slow spread of the insect population was explained by several factors, among them the tidal fluctuation of water, which has an impact on the population growth of the weevils. Whilst adults may be able to survive tidal fluctuations, larvae are severely impacted by them, contributing to the slow success of biological control. In this study, a significant increase in pathogen-induced disease severity and incidence was noted when Neochetina eichhorniae weevils were present, possibly because larvae tunnelling on the petiole created openings for the penetration of fungal spores. This study highlights the negative impacts of water hyacinth, on the environment, people, and thus economy of Cameroon. The presence of biological control agents and pathogens offers Cameroon the possibility of initiating and properly implementing the biological control option, or an integrated management solution, to manage water hyacinth in the Wouri Basin, and in the rest of Cameroon.
- Full Text:
- Authors: Voukeng, Sonia Nadege Kenfack
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7644 , vital:21281
- Description: The Wouri River, situated in the Wouri Basin, is one of the main rivers of the Littoral Region in the city of Douala in Cameroon. It is a source of income and food for the population living around these areas. Since the 1990s, the fishing, transportation, irrigation and sand extraction activities have been impeded by the invasion of aquatic plants, specifically water hyacinth (Eichhornia crassipes [Mart.] Solms-Laubach: Pontederiaceae). Introduced in 1997 to the shore of Lake Chad, water hyacinth has invaded almost 114 ha of the Wouri Basin. Furthermore, Douala, the economic capital of the Cameroon and location for more than 70% of the country’s industries, uses the Wouri River and its tributaries to deposit its effluent and waste, which has worsened the problem of water hyacinth. This thesis examined the ecological and socio-economic impacts of water hyacinth in the Wouri Basin and its possible control. An increase in the nutrients in the water has provided water hyacinth with appropriate conditions for its fast growth during both the rainy and dry seasons. The availability of nutrients in these areas is enhanced by the constant, daily tidal fluctuation of water, providing enough water to the plant for easy nutrient uptake. A survey of the impacts of water hyacinth on aquatic plant communities in the Wouri Basin showed that this plant is able to out-compete native species. Assessment of the impact of water hyacinth on the abundance and diversity of plant communities indicated that at some invaded sites, 65% of the vegetation consisted of water hyacinth. Species found in association with water hyacinth with a high level of abundance-dominance were Pistia stratiotes L. (Araceae) (another invader), Commelina benghalensis L. (Commelinaceae) and Echinochloa pyramidalis (Lam.) Hitchc. & Chase (Poaceae). This component of the study also showed that habitats rich in water hyacinth were poor in diversity, while habitats without water hyacinth were rich in diversity, thus raising awareness of the importance of monitoring invasive aquatic weeds along the Wouri Basin, and of implementing correct control management of all invasive aquatic weeds. Communities living along the invaded rivers are well aware of the range of problems caused by the weed; because as the rivers and water bodies used for fishing, transportation, and sand extraction are progressively invaded by the weed, the riparian population is the first to feel the impact. The impact on people has been noticeable, with an increase in diseases, such as malaria, cholera, diarrhoea, typhoid, filariasis, schistosomiasis, scabies and yellow fever increasing the need for a medicine and hospitalization. Economic losses due to the management of invasive aquatic weeds were recorded, and the Ministry of Environment spent an estimated US$1 200 000 between 2010 and 2015 to manage this scourge. In 2016, an amount of US$160 000 was transferred to these regions to manage invasive aquatic weeds, especially water hyacinth, although manual clearing is still the only method used to control this weed. Isolation of fungi from diseased water hyacinth plants in the Wouri Basin revealed several fungal species, most of which have been isolated from water hyacinth species in water bodies elsewhere, which showed a higher diversity during the dry season than during the rainy season. These fungi included Acremonium zonatum (Sawada). W. Gams (Hypocreaceae), Alternaria eichhorniae Nag Raj & Ponnappa (Pleosporaceae), Chaetomium sp., Colletotrichum sp., Curvularia pallescens Boedjin (Pleosporaceae), Curvalaria sp., Epicoccum nigrum Link (Pleosporaceae), Fusarium sp., Pithomyces chartarum fBerk. & M. A. Curtis) M. B. Ellis (Montagnulaceae), to a lesser extent Myrothecium roridum Tode ex Fr. (Incertae sedis) and Nigrospora sp. Although never released in Cameroon, arthropod biological control agents (Neochetina eichhorniae Warner (Coleoptera, Curculionidae) and N. bruchi Hustache (Coleoptera, Curculionidae)) were present, but their populations were relatively low. The slow spread of the insect population was explained by several factors, among them the tidal fluctuation of water, which has an impact on the population growth of the weevils. Whilst adults may be able to survive tidal fluctuations, larvae are severely impacted by them, contributing to the slow success of biological control. In this study, a significant increase in pathogen-induced disease severity and incidence was noted when Neochetina eichhorniae weevils were present, possibly because larvae tunnelling on the petiole created openings for the penetration of fungal spores. This study highlights the negative impacts of water hyacinth, on the environment, people, and thus economy of Cameroon. The presence of biological control agents and pathogens offers Cameroon the possibility of initiating and properly implementing the biological control option, or an integrated management solution, to manage water hyacinth in the Wouri Basin, and in the rest of Cameroon.
- Full Text:
An exploration of the prior conceptual understanding of measurement of first year national certificate (vocational) Engineering students
- Authors: Vale, Pamela
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/8033 , vital:21337
- Description: Measurement is acknowledged to be a critical component in mathematics education and is particularly important for vocational Engineering students, for whom this is a key skill required in the workplace. The goal of this research was to explore the existing measurement conceptualisations of vocational Engineering students at the outset of their course, as evident in their engagement with mediated measurement tasks. The focus on students’ prior knowledge in measurement, was for the value that this awareness holds in understanding the learning needs of the students. Students participated in five measurement tasks. Four took the form of dynamically assessed task-based interviews, and the fifth was a written test assessing what they had learned during their Mathematics classes. Domains of measurement that were assessed in these tasks included length, area, surface area, volume and flow rate. The interviewer took the role of mediator and students were assessed according to the number of moments of mediation and the degree of mediation required to successfully complete the task. Students’ responsiveness to this mediation provided insight as to their conceptualisations of the measurements relevant to the task. This research was exploratory in nature and adopted an open and flexible approach to the data analysis. Critical incidents were identified and coded according to the mediation offered and the actions of the students during the measuring activity. This allowed patterns to emerge that revealed stable and emerging conceptualisations that related to embodied and symbolic aspects of measurement. Evidence was found that for many of these students the link between the embodied and symbolic aspects of the concept was broken. This insight allowed suggestions to be formulated about how better to facilitate these students’ learning of measurement.
- Full Text:
- Authors: Vale, Pamela
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/8033 , vital:21337
- Description: Measurement is acknowledged to be a critical component in mathematics education and is particularly important for vocational Engineering students, for whom this is a key skill required in the workplace. The goal of this research was to explore the existing measurement conceptualisations of vocational Engineering students at the outset of their course, as evident in their engagement with mediated measurement tasks. The focus on students’ prior knowledge in measurement, was for the value that this awareness holds in understanding the learning needs of the students. Students participated in five measurement tasks. Four took the form of dynamically assessed task-based interviews, and the fifth was a written test assessing what they had learned during their Mathematics classes. Domains of measurement that were assessed in these tasks included length, area, surface area, volume and flow rate. The interviewer took the role of mediator and students were assessed according to the number of moments of mediation and the degree of mediation required to successfully complete the task. Students’ responsiveness to this mediation provided insight as to their conceptualisations of the measurements relevant to the task. This research was exploratory in nature and adopted an open and flexible approach to the data analysis. Critical incidents were identified and coded according to the mediation offered and the actions of the students during the measuring activity. This allowed patterns to emerge that revealed stable and emerging conceptualisations that related to embodied and symbolic aspects of measurement. Evidence was found that for many of these students the link between the embodied and symbolic aspects of the concept was broken. This insight allowed suggestions to be formulated about how better to facilitate these students’ learning of measurement.
- Full Text:
Evidence for a biological control-induced regime shift between floating and submerged invasive plant dominance in South Africa
- Authors: Strange, Emily Frances
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32448 , vital:24044
- Description: South Africa has a long history battling the establishment and spread of invasive floating macrophytes. The negative consequences of these are costly both economically and ecologically. They form dense mats on the water's surface that deplete resources such as light and oxygen to the submerged community, which creates anoxic conditions, reduces biodiversity and limits access to freshwater. The past thirty years of South African invasive plant research and the implementation of nationwide biological control programmes has led to widespread control of these species in many degraded systems. Such initiatives are aimed at restoring access to potable freshwater and increasing native biodiversity. However, in recent years, where there has been a decline in floating invasive plant populations, an increase in the establishment and spread of submerged invasive plant species has been observed. Species such as Brazilian waterweed (Egeria densa (Planch.) (Hydrocharitaceae)) and Eurasian watermilfoil (Myriophyllum spicatum (L.) (Haloragaceae)) have been recorded in South African freshwater systems, posing significant threats to aquatic ecosystems. This thesis proposes that the biological control of floating invasive plants, which occurs in numerous dams and rivers nationwide, is the catalyst of a regime shift from floating invasive to submerged invasive plant dominance. Regime shifts are large and often sudden changes in the key structure and functioning of ecosystems, and studies into their occurrence and driving mechanisms broadens understanding of community structures and can guide effective resource management. In order to explore the existence of this new regime shift, a multi-platform approach using controlled experiments and ecological modelling techniques was employed. A model system was created consisting of a floating invasive (Pistia stratiotes L. (Araceae)), a submerged invasive (E. densa) and an ecologically analogous submerged native plant species (Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae)). A suite of experiments was conducted to explore the interactions between the floating and submerged plants under varying regimes of floating plant biological control and levels of nutrient loading. These experiments revealed a competitive advantage of the invasive E. densa over the native L. major that increased by 86% under heavy nutrient loading. The relative growth rate and accumulated biomass of E. densa was significantly higher for plants grown in the presence of biologically controlled P. stratiotes (compared to insect free plants). This demonstrates a high capacity for the invasive E. densa to capitalise on resources made newly available through the biological control of the floating plants. In contrast, the native L. major fared poorly when grown in the presence of the floating P. stratiotes, regardless of applied biological control measures. The experimental observations were then used to parameterise a mathematical model, built to provide a holistic understanding of the individually assessed interactions which work together as the driving mechanisms underpinning the newly identified regime shift. This thesis utilised a multi-platform approach to build the first body of evidence in support of a newly recognised regime shift between floating invasive and submerged invasive plant dominance, as driven by biological control. The results indicate that a reduction in the nutrient loading of South Africa's freshwater systems will reduce negative impacts of submerged invasive macrophytes, whilst increasing system resilience against future invasion. The evidence presented has the potential to better inform management of South Africa's freshwater systems and highlights the importance of integrating multi-trophic interactions when considering future invasive plant management. This research also opens up a multitude of possibilities for studies into submerged plant invasion mechanisms and resilience of native macrophyte communities in South Africa, and further afield.
- Full Text:
- Authors: Strange, Emily Frances
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/32448 , vital:24044
- Description: South Africa has a long history battling the establishment and spread of invasive floating macrophytes. The negative consequences of these are costly both economically and ecologically. They form dense mats on the water's surface that deplete resources such as light and oxygen to the submerged community, which creates anoxic conditions, reduces biodiversity and limits access to freshwater. The past thirty years of South African invasive plant research and the implementation of nationwide biological control programmes has led to widespread control of these species in many degraded systems. Such initiatives are aimed at restoring access to potable freshwater and increasing native biodiversity. However, in recent years, where there has been a decline in floating invasive plant populations, an increase in the establishment and spread of submerged invasive plant species has been observed. Species such as Brazilian waterweed (Egeria densa (Planch.) (Hydrocharitaceae)) and Eurasian watermilfoil (Myriophyllum spicatum (L.) (Haloragaceae)) have been recorded in South African freshwater systems, posing significant threats to aquatic ecosystems. This thesis proposes that the biological control of floating invasive plants, which occurs in numerous dams and rivers nationwide, is the catalyst of a regime shift from floating invasive to submerged invasive plant dominance. Regime shifts are large and often sudden changes in the key structure and functioning of ecosystems, and studies into their occurrence and driving mechanisms broadens understanding of community structures and can guide effective resource management. In order to explore the existence of this new regime shift, a multi-platform approach using controlled experiments and ecological modelling techniques was employed. A model system was created consisting of a floating invasive (Pistia stratiotes L. (Araceae)), a submerged invasive (E. densa) and an ecologically analogous submerged native plant species (Lagarosiphon major (Ridl.) Moss (Hydrocharitaceae)). A suite of experiments was conducted to explore the interactions between the floating and submerged plants under varying regimes of floating plant biological control and levels of nutrient loading. These experiments revealed a competitive advantage of the invasive E. densa over the native L. major that increased by 86% under heavy nutrient loading. The relative growth rate and accumulated biomass of E. densa was significantly higher for plants grown in the presence of biologically controlled P. stratiotes (compared to insect free plants). This demonstrates a high capacity for the invasive E. densa to capitalise on resources made newly available through the biological control of the floating plants. In contrast, the native L. major fared poorly when grown in the presence of the floating P. stratiotes, regardless of applied biological control measures. The experimental observations were then used to parameterise a mathematical model, built to provide a holistic understanding of the individually assessed interactions which work together as the driving mechanisms underpinning the newly identified regime shift. This thesis utilised a multi-platform approach to build the first body of evidence in support of a newly recognised regime shift between floating invasive and submerged invasive plant dominance, as driven by biological control. The results indicate that a reduction in the nutrient loading of South Africa's freshwater systems will reduce negative impacts of submerged invasive macrophytes, whilst increasing system resilience against future invasion. The evidence presented has the potential to better inform management of South Africa's freshwater systems and highlights the importance of integrating multi-trophic interactions when considering future invasive plant management. This research also opens up a multitude of possibilities for studies into submerged plant invasion mechanisms and resilience of native macrophyte communities in South Africa, and further afield.
- Full Text:
The making of ‘loyals’ and ‘rebels’: the 1880 Transkei Rebellion and the Subversion of the chieftaincies of East Griqualand, 1874-1914
- Authors: Snell, Milner Charles
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41860 , vital:25142
- Description: In the mid-1870s, influenced by the mineral revolution in southern Africa, the Cape responsible government began to extend colonial rule over the chiefdoms that inhabited the Mthatha- Mzimkhulu region. Although white officials initially negotiated with the leadership of these chiefdoms to accept colonial rule and depended heavily on them to implement new laws, ultimately the Cape government aimed to side-line indigenous political systems and replace them with magistrates and headmen. Colonial officials mistakenly equated indigenous political structures with dictatorial chiefs whose followers were subject to their personal ambitions. In fact chiefs were part of a collective leadership and were very aware and influenced by the needs of their adherents. This work is concerned with how the chieftaincies, or indigenous political systems, of the Mthatha-Mzimkhulu region responded, survived and adapted in the face of colonialism. The chieftaincies were remarkably resilient despite the political and economic changes brought on by colonialism and capitalism and were able to retain some degree of authority amongst their followers and at times obtain recognition from the colonial state. Interactions between the chieftaincies and the colonial state were complex, fluid and ever evolving. Some leaders of chiefdoms co-operated with colonial authorities, either over particular issues at certain times or more generally over longer periods, and were considered by colonial officials to be ‘loyal’. Yet, at other times they resisted the demands and changes being brought on by colonialism and were labelled as ‘rebels’. Questions of how the chieftaincies responded to colonial rule were most critical during the Transkei Rebellion of 1880, which is a central focus of this work. Some chieftaincies co-operated with and served with the colonial military forces in order to spare themselves from the economic and social disruption brought on by war and the confiscation of land by the victors. Other chieftaincies took up arms against the colonial state in an attempt to stop the increasingly unacceptable demands being made of them and to resist the negative changes that colonialism was bringing. Despite their ability to adapt, by the early years of the twentieth century hereditary leaders found themselves increasingly caught between the expectations of their followers and demands made by the colonial administration. Faced with increasing popular criticism, many leaders adapted ambiguous and shifting stances on issues concerning their followers.
- Full Text:
- Authors: Snell, Milner Charles
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41860 , vital:25142
- Description: In the mid-1870s, influenced by the mineral revolution in southern Africa, the Cape responsible government began to extend colonial rule over the chiefdoms that inhabited the Mthatha- Mzimkhulu region. Although white officials initially negotiated with the leadership of these chiefdoms to accept colonial rule and depended heavily on them to implement new laws, ultimately the Cape government aimed to side-line indigenous political systems and replace them with magistrates and headmen. Colonial officials mistakenly equated indigenous political structures with dictatorial chiefs whose followers were subject to their personal ambitions. In fact chiefs were part of a collective leadership and were very aware and influenced by the needs of their adherents. This work is concerned with how the chieftaincies, or indigenous political systems, of the Mthatha-Mzimkhulu region responded, survived and adapted in the face of colonialism. The chieftaincies were remarkably resilient despite the political and economic changes brought on by colonialism and capitalism and were able to retain some degree of authority amongst their followers and at times obtain recognition from the colonial state. Interactions between the chieftaincies and the colonial state were complex, fluid and ever evolving. Some leaders of chiefdoms co-operated with colonial authorities, either over particular issues at certain times or more generally over longer periods, and were considered by colonial officials to be ‘loyal’. Yet, at other times they resisted the demands and changes being brought on by colonialism and were labelled as ‘rebels’. Questions of how the chieftaincies responded to colonial rule were most critical during the Transkei Rebellion of 1880, which is a central focus of this work. Some chieftaincies co-operated with and served with the colonial military forces in order to spare themselves from the economic and social disruption brought on by war and the confiscation of land by the victors. Other chieftaincies took up arms against the colonial state in an attempt to stop the increasingly unacceptable demands being made of them and to resist the negative changes that colonialism was bringing. Despite their ability to adapt, by the early years of the twentieth century hereditary leaders found themselves increasingly caught between the expectations of their followers and demands made by the colonial administration. Faced with increasing popular criticism, many leaders adapted ambiguous and shifting stances on issues concerning their followers.
- Full Text:
From dialect to ‘official’ language: towards the intellectualisation of Ndau in Zimbabwe
- Authors: Sithole, Emmanuel
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6086 , vital:21030
- Full Text:
- Authors: Sithole, Emmanuel
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/6086 , vital:21030
- Full Text:
William Blake’s animal symbols: tensions and intersections between science and allegory In Eighteenth-Century attitudes towards animals
- Authors: Singh, Jyoti
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4590 , vital:20696
- Description: This thesis explores the tensions and intersections between science, allegory, and related eighteenth-century attitudes towards animals in William Blake’s poetry through detailed analysis of individual animal symbols and tropes. It will focus specifically on the period between 1794 and 1820, to coincide with the dates of Blake’s major works. Chapter One outlines Blake’s key philosophies, concentrating on his particular approach to symbolism. By rejecting certain Enlightenment ideals and beliefs surrounding allegory, Blake created his own form of the literary tradition, and the subjects and symbols of his poetry clearly demonstrate shifting allegorical frames. The chapter also explains why he argued for the recognition, and even valorisation, of the imaginative faculty, or “Poetic Genius”, in an era which accepted reason and rational thinking as one of the main means of apprehending the world. Chapter Two considers the significance of Blake’s use of predatory animals in the SONGS Of INNOCENCE and Of EXPERIENCE. In focussing on symbolic animals, the chapter assesses whether the ‘real’ animals (with all their scientific associations) are alluded to, and the extent to which they influence their symbolic counterparts. In choosing these symbols to represent key themes throughout his oeuvre, Blake drew on some familiar associations and contemporary attitudes towards animals, but offered no critique of society’s attitudes to animals. Chapter Three identifies and analyses the “fragments of Eternity” represented in the contraries of “Good” and “Evil”, and “Energy” and “Reason” embodied by the animals in THE MARRIAGE of HEAVEN and HELL. The symbols’ division between “Reason” and “Energy” develops an understanding of the complex attitudes towards animals, both in Blake’s mind, and in that of the eighteenth-century British public. Chapter Four is concerned with Blake’s depictions of the Worm and Serpent in his poetry, and how his conception of “Beulah” provides more insight into these symbols and their functions. It also grapples with Rod Preece’s argument that the poet recognised the sanctity and divinity in all forms of life, and sought to endorse these beliefs through his animal symbols. As the thesis illustrates, though, Blake is not arguing for the sanctity of all life to be upheld, nor does he see any divinity in the beings and objects found in nature. Sanctity and divinity are constructs of the imagination, and it is through exercising the imaginative faculty - the “Poetic Genius’’ - along with our senses and instincts, that we are able to make sense of the world. The study thus concludes by considering the extent to which ‘real’ animals intrude upon Blake’s oeuvre, and attempts to determine the value of reading the symbols through an “animal studies” paradigm. It also argues that ‘real’ animals are inseparable from their cultural and symbolic representations, because these are the only means of interpretation we have.
- Full Text:
- Authors: Singh, Jyoti
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4590 , vital:20696
- Description: This thesis explores the tensions and intersections between science, allegory, and related eighteenth-century attitudes towards animals in William Blake’s poetry through detailed analysis of individual animal symbols and tropes. It will focus specifically on the period between 1794 and 1820, to coincide with the dates of Blake’s major works. Chapter One outlines Blake’s key philosophies, concentrating on his particular approach to symbolism. By rejecting certain Enlightenment ideals and beliefs surrounding allegory, Blake created his own form of the literary tradition, and the subjects and symbols of his poetry clearly demonstrate shifting allegorical frames. The chapter also explains why he argued for the recognition, and even valorisation, of the imaginative faculty, or “Poetic Genius”, in an era which accepted reason and rational thinking as one of the main means of apprehending the world. Chapter Two considers the significance of Blake’s use of predatory animals in the SONGS Of INNOCENCE and Of EXPERIENCE. In focussing on symbolic animals, the chapter assesses whether the ‘real’ animals (with all their scientific associations) are alluded to, and the extent to which they influence their symbolic counterparts. In choosing these symbols to represent key themes throughout his oeuvre, Blake drew on some familiar associations and contemporary attitudes towards animals, but offered no critique of society’s attitudes to animals. Chapter Three identifies and analyses the “fragments of Eternity” represented in the contraries of “Good” and “Evil”, and “Energy” and “Reason” embodied by the animals in THE MARRIAGE of HEAVEN and HELL. The symbols’ division between “Reason” and “Energy” develops an understanding of the complex attitudes towards animals, both in Blake’s mind, and in that of the eighteenth-century British public. Chapter Four is concerned with Blake’s depictions of the Worm and Serpent in his poetry, and how his conception of “Beulah” provides more insight into these symbols and their functions. It also grapples with Rod Preece’s argument that the poet recognised the sanctity and divinity in all forms of life, and sought to endorse these beliefs through his animal symbols. As the thesis illustrates, though, Blake is not arguing for the sanctity of all life to be upheld, nor does he see any divinity in the beings and objects found in nature. Sanctity and divinity are constructs of the imagination, and it is through exercising the imaginative faculty - the “Poetic Genius’’ - along with our senses and instincts, that we are able to make sense of the world. The study thus concludes by considering the extent to which ‘real’ animals intrude upon Blake’s oeuvre, and attempts to determine the value of reading the symbols through an “animal studies” paradigm. It also argues that ‘real’ animals are inseparable from their cultural and symbolic representations, because these are the only means of interpretation we have.
- Full Text:
Physical organic studies of substituted norbornyl systems: aspects of mechanisms and chirality
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
- Authors: Singh, Alicia
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/50558 , vital:25999
- Description: Fenchone and camphor are essential natural products that are available optically pure and contribute to the chiral pool in asymmetric synthesis. Further, they are both derivatives of norbornane, a structure that undergoes a remarkable diversity of rearrangements in acidic conditions. This work explores two aspects of the camphor/fenchone derived systems. Firstly an attempt to clarify rearrangement mechanisms on a camphor system successfully via deuterium labelling and unsuccessfully via derivatization of fenchone (with rearrangement) to produce other 13C-labelled camphor substitutions, has resulted in confirmation of a theoretically proposed, highly concerted Wagner-Meerwein, 6,2 - hydride shift, Wagner-Meerwein rearrangement in competition with an associated 2,3-methide shift. Kinetics and activation parameters for many steps have been resolved in this rearrangement of the deuterium labelled camphor-derived tosylate system to two pairs of isotopomers. Further, the kinetics and formation of an unexpected pair of dimers encountered during the scheme for 13C labelling are investigated in detail. These dimers (forming during the initial stages of the synthetic scheme) are unusual in that they are not expected rotamers of each other, but diastereomers resulting from chirality of a sulfur atom in a sulfite moiety. A feasible mechanism of formation that matches the kinetics has been proposed in this unexpectedly complex system, and thermodynamic parameters have been determined. The second aspect of substituted norbornyl systems pertains to their chirality, and the influence of this chirality on reaction mixtures, with an aim to identify novel chiral micellar catalysts for use in heterogeneous reaction mixtures. Headway has been made towards the synthesis of the appropriate surfactants to be used in the construction of these micelles, but extensive molecular dynamics simulations have illustrated the feasibility of forming the stable chiral micelles in a dual-solvent system, and detail precisely the influence of chirality on surrounding media. These studies add important physical organic data as well as show the immense possibilities pertaining to substituted norbornane systems.
- Full Text:
Talent management: a case study of Namibia’s Directorate of Civil Aviation (DCA) in securing talent for aviation safety, 2008 to 2014
- Authors: Simataa, George
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7131 , vital:21220
- Description: This study is about talent management, focusing on a case study of the initiatives undertaken by the Directorate of Civil Aviation (DCA) of Namibia over the period 2008 to 2014 in securing talent for aviation safety. The International Civil Aviation Organisation (ICAO) regularly assesses the extent to which member states comply with their safety oversight responsibilities. According to a 1996 report by the ICAO, under the auspices of its Universal Safety Oversight and Security Audit Programme (USOSAP), Namibia’s safety oversight was found to be weak, as indicative of the State’s inability to guarantee the safety of aircraft operations within the national airspace (ICAO, 1996). One of the significant audit findings was the critical shortage of qualified professionals at the Directorate Civil Aviation (DCA) to effectively perform the State’s regulatory and oversight function as contained in the Chicago Convention of 1944. The shortage of qualified professionals resulted in Namibia being unable to respond to its obligations and responsibilities under the Chicago Convention and Namibia’s subsequent blacklisting by the ICAO Audit Result Review Board (ARRB). Consequently, a corrective action plan was undertaken. This study examines one aspect of this plan, namely the initiatives that were undertaken to secure the talent required for aviation safety posts. The aim of the research is, from the perspective of talent management, to analyse the corrective action plan of the Directorate of Civil Aviation (DCA), as a process of securing talent for strategic positions in aviation safety in Namibia. This initiative was analysed from the perspective of the fourth stream of talent management, which emphasises securing talent for strategic positions (Collings and Mellahi, 2009; Huselid & Becker, 2011). Taking into account the fact that Namibia was a racially and culturally divided society until about 25 years ago, the study also deals with issues of diversity management as they impacted upon the talent management of the civil aviation industry nationally. Furthermore, the study is located against the background of the Bantu Education System that was provided by the apartheid South African government to Namibians before independence in 1990. The research design of this study involved conducting a case study that followed a deductive approach. Data were collected using multiple methods and sources such as documentation, interviews and archival records. Content analysis was used in the analysis of collected data. The findings of the study showed the talent management strategies that were adopted in managing strategic positions, the challenges encountered and the impact of the programme. The findings were initially discussed from the perspective of stream four of talent management, with its focus on strategic positions in organisations. Some of the findings of the study were in line with this approach to talent management, but certain challenges that were encountered in carrying out the talent management programme could not be addressed from this perspective, thereby exposing the limits of this approach to talent management in an emerging economy like Namibia. Consequently, a proposed model of sustainable talent management for the DCA was developed. From the perspective of this model of sustainable talent management, recommendations were made for practice and further research.
- Full Text:
- Authors: Simataa, George
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7131 , vital:21220
- Description: This study is about talent management, focusing on a case study of the initiatives undertaken by the Directorate of Civil Aviation (DCA) of Namibia over the period 2008 to 2014 in securing talent for aviation safety. The International Civil Aviation Organisation (ICAO) regularly assesses the extent to which member states comply with their safety oversight responsibilities. According to a 1996 report by the ICAO, under the auspices of its Universal Safety Oversight and Security Audit Programme (USOSAP), Namibia’s safety oversight was found to be weak, as indicative of the State’s inability to guarantee the safety of aircraft operations within the national airspace (ICAO, 1996). One of the significant audit findings was the critical shortage of qualified professionals at the Directorate Civil Aviation (DCA) to effectively perform the State’s regulatory and oversight function as contained in the Chicago Convention of 1944. The shortage of qualified professionals resulted in Namibia being unable to respond to its obligations and responsibilities under the Chicago Convention and Namibia’s subsequent blacklisting by the ICAO Audit Result Review Board (ARRB). Consequently, a corrective action plan was undertaken. This study examines one aspect of this plan, namely the initiatives that were undertaken to secure the talent required for aviation safety posts. The aim of the research is, from the perspective of talent management, to analyse the corrective action plan of the Directorate of Civil Aviation (DCA), as a process of securing talent for strategic positions in aviation safety in Namibia. This initiative was analysed from the perspective of the fourth stream of talent management, which emphasises securing talent for strategic positions (Collings and Mellahi, 2009; Huselid & Becker, 2011). Taking into account the fact that Namibia was a racially and culturally divided society until about 25 years ago, the study also deals with issues of diversity management as they impacted upon the talent management of the civil aviation industry nationally. Furthermore, the study is located against the background of the Bantu Education System that was provided by the apartheid South African government to Namibians before independence in 1990. The research design of this study involved conducting a case study that followed a deductive approach. Data were collected using multiple methods and sources such as documentation, interviews and archival records. Content analysis was used in the analysis of collected data. The findings of the study showed the talent management strategies that were adopted in managing strategic positions, the challenges encountered and the impact of the programme. The findings were initially discussed from the perspective of stream four of talent management, with its focus on strategic positions in organisations. Some of the findings of the study were in line with this approach to talent management, but certain challenges that were encountered in carrying out the talent management programme could not be addressed from this perspective, thereby exposing the limits of this approach to talent management in an emerging economy like Namibia. Consequently, a proposed model of sustainable talent management for the DCA was developed. From the perspective of this model of sustainable talent management, recommendations were made for practice and further research.
- Full Text:
Evolving an efficient and effective off-the-shelf computing infrastructure for schools in rural areas of South Africa
- Authors: Siebörger, Ingrid Gisélle
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/14557 , vital:21938
- Description: Upliftment of rural areas and poverty alleviation are priorities for development in South Africa. Information and knowledge are key strategic resources for social and economic development and ICTs act as tools to support them, enabling innovative and more cost effective approaches. In order for ICT interventions to be possible, infrastructure has to be deployed. For the deployment to be effective and sustainable, the local community needs to be involved in shaping and supporting it. This study describes the technical work done in the Siyakhula Living Lab (SLL), a long-term ICT4D experiment in the Mbashe Municipality, with a focus on the deployment of ICT infrastructure in schools, for teaching and learning but also for use by the communities surrounding the schools. As a result of this work, computing infrastructure was deployed, in various phases, in 17 schools in the area and a “broadband island” connecting them was created. The dissertation reports on the initial deployment phases, discussing theoretical underpinnings and policies for using technology in education as well various computing and networking technologies and associated policies available and appropriate for use in rural South African schools. This information forms the backdrop of a survey conducted with teachers from six schools in the SLL, together with experimental work towards the provision of an evolved, efficient and effective off-the-shelf computing infrastructure in selected schools, in order to attempt to address the shortcomings of the computing infrastructure deployed initially in the SLL. The result of the study is the proposal of an evolved computing infrastructure model for use in rural South African schools.
- Full Text:
- Authors: Siebörger, Ingrid Gisélle
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/14557 , vital:21938
- Description: Upliftment of rural areas and poverty alleviation are priorities for development in South Africa. Information and knowledge are key strategic resources for social and economic development and ICTs act as tools to support them, enabling innovative and more cost effective approaches. In order for ICT interventions to be possible, infrastructure has to be deployed. For the deployment to be effective and sustainable, the local community needs to be involved in shaping and supporting it. This study describes the technical work done in the Siyakhula Living Lab (SLL), a long-term ICT4D experiment in the Mbashe Municipality, with a focus on the deployment of ICT infrastructure in schools, for teaching and learning but also for use by the communities surrounding the schools. As a result of this work, computing infrastructure was deployed, in various phases, in 17 schools in the area and a “broadband island” connecting them was created. The dissertation reports on the initial deployment phases, discussing theoretical underpinnings and policies for using technology in education as well various computing and networking technologies and associated policies available and appropriate for use in rural South African schools. This information forms the backdrop of a survey conducted with teachers from six schools in the SLL, together with experimental work towards the provision of an evolved, efficient and effective off-the-shelf computing infrastructure in selected schools, in order to attempt to address the shortcomings of the computing infrastructure deployed initially in the SLL. The result of the study is the proposal of an evolved computing infrastructure model for use in rural South African schools.
- Full Text:
The effects of graphene and other nanomaterials on the electrocatalytic behaviour of phthalocyanines
- Authors: Shumba, Munyaradzi
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/37952 , vital:24712
- Description: Carbon based nanomaterials, gold nanorods and metallophthalocyanine nanoconjugates have been developed for electrocatalysis. Carbon based nanomaterials used are multiwalled carbon nanotubes, pristine graphene oxide nanosheets, nitrogen, boron, sulphur, phosphorus doped graphene oxide nanosheets. Cobalt phthalocyanine (CoPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPhPc), cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) and cobalt tetra carboxyphenoxy phthalocyanine (CoTCPhPc) are the phthalocyanines employed in this work. Metallophthalocyanines were employed either in their bulk form or in their nanosized form. Electrode modification by these nanomaterials was either done sequentially, premixed or linked nanoconjugates. In all sequential modification, phthalocyanines were employed on top of other nanomaterials. Sequentially modified electrodes gave higher detection currents than both premixed and covalently bonded nanoconjugates. The nanomaterials reported here were characterised by transmission electron microscopy, Raman spectroscopy, time of flight secondary ion mass spectrometry, and X-ray diffraction among other techniques. The modified electrodes were further characterised by scanning electron microscopy, scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry, while square wave, linear scan and cyclic voltammetry, rotating disc electrode and chronoamperometry have been used to evaluate the electrocatalytic behaviour of the previously mentioned towards either oxidation or reduction of L-cysteine and/or hydrogen peroxide respectively. Generally, the nanoconjugates resulted in superior catalytic performance compared to the performance of individual nanomaterials. Zinc octacarboxy phthalocyanine (ZnOCPc) conjugated to either GONS or rGONS were employed to compare electrocatalytic detection of hydrogen peroxide to its luminescence sensing.
- Full Text:
The effects of graphene and other nanomaterials on the electrocatalytic behaviour of phthalocyanines
- Authors: Shumba, Munyaradzi
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/37952 , vital:24712
- Description: Carbon based nanomaterials, gold nanorods and metallophthalocyanine nanoconjugates have been developed for electrocatalysis. Carbon based nanomaterials used are multiwalled carbon nanotubes, pristine graphene oxide nanosheets, nitrogen, boron, sulphur, phosphorus doped graphene oxide nanosheets. Cobalt phthalocyanine (CoPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPc), cobalt tetra aminophenoxy phthalocyanine (CoTAPhPc), cobalt mono carboxyphenoxy phthalocyanine (CoMCPhPc) and cobalt tetra carboxyphenoxy phthalocyanine (CoTCPhPc) are the phthalocyanines employed in this work. Metallophthalocyanines were employed either in their bulk form or in their nanosized form. Electrode modification by these nanomaterials was either done sequentially, premixed or linked nanoconjugates. In all sequential modification, phthalocyanines were employed on top of other nanomaterials. Sequentially modified electrodes gave higher detection currents than both premixed and covalently bonded nanoconjugates. The nanomaterials reported here were characterised by transmission electron microscopy, Raman spectroscopy, time of flight secondary ion mass spectrometry, and X-ray diffraction among other techniques. The modified electrodes were further characterised by scanning electron microscopy, scanning electrochemical microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry, while square wave, linear scan and cyclic voltammetry, rotating disc electrode and chronoamperometry have been used to evaluate the electrocatalytic behaviour of the previously mentioned towards either oxidation or reduction of L-cysteine and/or hydrogen peroxide respectively. Generally, the nanoconjugates resulted in superior catalytic performance compared to the performance of individual nanomaterials. Zinc octacarboxy phthalocyanine (ZnOCPc) conjugated to either GONS or rGONS were employed to compare electrocatalytic detection of hydrogen peroxide to its luminescence sensing.
- Full Text:
Nonlinear optical behavior of lanthanide phthalocyanines and their conjugates with a selection of nanomaterials
- Authors: Sekhosana, Kutloano Edward
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4580 , vital:20695
- Description: This thesis presents novel asymmetrical and symmetrical lanthanide phthalocyanines (Pcs) characterized using a number techniques including proton nuclear magnetic resonance, electron spin resonance, time correlated single photon counting, FTIR spectrometry, MALDI-TOF mass spectrometry, UV-Vis spectrometry, Raman spectroscopy and CHNS elemental analysis. The design of theses lanthanide Pcs takes the form of mononuclear, binuclear, trinuclear, bis- and tris(phthalocyanines). Nanomaterials such as zinc oxide nanoparticles (ZnO NPs), multi-walled carbon nanotubes (MWCNTs) and graphene oxide nanosheets (GONS) (oxidized and reduced) were employed for covalent linkage to mono- and binuclear phthalocyanines as conjugates. Transmission electron microscopy was used to characterize ZnO NPs, MWCNTs and GONS alone and when linked to lanthanide Pcs. Lanthanide Pcs alone and when linked to ZnO NPs, MWCNTs and GONS where embedded in polymers such as poly (methyl methacrylate) (PMMA), poly (bisphenol A carbonate) (PBC) and poly (acrylic acid) (PAA) for thin film preparation. The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction (XRD). Optical limiting properties of lanthanide Pcs alone and as conjugates in solution and when incorporated into polymers were determined by employing a Z-scan technique. It emerged that low symmetry lanthanide Pcs (19, 20 and 21), the blue forms of bis(phthalocyanines) (only in solution; 24 and 28) as well as tris(phthalocyanines) (30 and 31) exhibit low limiting threshold (Ilim) values in solution and thin films (particularly PBC and PAA). The low limiting threshold values make these lanthanide Pcs reliable optical limiters.
- Full Text:
- Authors: Sekhosana, Kutloano Edward
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/4580 , vital:20695
- Description: This thesis presents novel asymmetrical and symmetrical lanthanide phthalocyanines (Pcs) characterized using a number techniques including proton nuclear magnetic resonance, electron spin resonance, time correlated single photon counting, FTIR spectrometry, MALDI-TOF mass spectrometry, UV-Vis spectrometry, Raman spectroscopy and CHNS elemental analysis. The design of theses lanthanide Pcs takes the form of mononuclear, binuclear, trinuclear, bis- and tris(phthalocyanines). Nanomaterials such as zinc oxide nanoparticles (ZnO NPs), multi-walled carbon nanotubes (MWCNTs) and graphene oxide nanosheets (GONS) (oxidized and reduced) were employed for covalent linkage to mono- and binuclear phthalocyanines as conjugates. Transmission electron microscopy was used to characterize ZnO NPs, MWCNTs and GONS alone and when linked to lanthanide Pcs. Lanthanide Pcs alone and when linked to ZnO NPs, MWCNTs and GONS where embedded in polymers such as poly (methyl methacrylate) (PMMA), poly (bisphenol A carbonate) (PBC) and poly (acrylic acid) (PAA) for thin film preparation. The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction (XRD). Optical limiting properties of lanthanide Pcs alone and as conjugates in solution and when incorporated into polymers were determined by employing a Z-scan technique. It emerged that low symmetry lanthanide Pcs (19, 20 and 21), the blue forms of bis(phthalocyanines) (only in solution; 24 and 28) as well as tris(phthalocyanines) (30 and 31) exhibit low limiting threshold (Ilim) values in solution and thin films (particularly PBC and PAA). The low limiting threshold values make these lanthanide Pcs reliable optical limiters.
- Full Text:
A critical evaluation of inter-jurisdictional rules in the South African value-added tax system
- Authors: Schneider, Ferdinand Dirk
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7971 , vital:21329
- Description: This study analysed the current inter-jurisdictional rules in the South African Value-Added Tax (VAT) system, identified shortcomings, and proposed legislative amendments or additions to address these shortcomings. The research was conducted within an interpretative post positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the theoretical basis of a good tax system and the theory underpinning indirect and consumption taxation. The literature review also included an in-depth analysis of the South African VAT system and its treatment of resident and non-resident businesses with a South African physical or economic reach, and its treatment of local and cross-border transactions, including imported services. The literature review also considered the international VAT treatment of these transactions. To obtain a wider range of expert opinions regarding shortcomings in inter-jurisdictional rules in the South African VAT system, data was collected through structured interviews with South African and global VAT and indirect tax experts, using a questionnaire that was specifically designed for this purpose. This study proposed amendments and additions to the VAT Act, dealing with the VAT registration of non-resident suppliers; addressing various issues relating to the interjurisdictional VAT rate; proposing measures in connection with imported services; and legislating the intention of the legislator to tax final utilisation or consumption. The study finally recommended the introduction of a general place of supply rule linked to residency; specific place of supply rules for electronic, broadcasting, and telecommunication services; and zero rating provisions for electronic, broadcasting, and telecommunication services provided to non-resident suppliers by resident suppliers for services initiated outside South Africa.
- Full Text:
- Authors: Schneider, Ferdinand Dirk
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7971 , vital:21329
- Description: This study analysed the current inter-jurisdictional rules in the South African Value-Added Tax (VAT) system, identified shortcomings, and proposed legislative amendments or additions to address these shortcomings. The research was conducted within an interpretative post positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the theoretical basis of a good tax system and the theory underpinning indirect and consumption taxation. The literature review also included an in-depth analysis of the South African VAT system and its treatment of resident and non-resident businesses with a South African physical or economic reach, and its treatment of local and cross-border transactions, including imported services. The literature review also considered the international VAT treatment of these transactions. To obtain a wider range of expert opinions regarding shortcomings in inter-jurisdictional rules in the South African VAT system, data was collected through structured interviews with South African and global VAT and indirect tax experts, using a questionnaire that was specifically designed for this purpose. This study proposed amendments and additions to the VAT Act, dealing with the VAT registration of non-resident suppliers; addressing various issues relating to the interjurisdictional VAT rate; proposing measures in connection with imported services; and legislating the intention of the legislator to tax final utilisation or consumption. The study finally recommended the introduction of a general place of supply rule linked to residency; specific place of supply rules for electronic, broadcasting, and telecommunication services; and zero rating provisions for electronic, broadcasting, and telecommunication services provided to non-resident suppliers by resident suppliers for services initiated outside South Africa.
- Full Text:
A political discourse analysis of social memory, collective identity and nation-building in the Sunday Mail and the Standard of Zimbabwe between 1999 and 2013
- Authors: Santos, Phillip
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41753 , vital:25130
- Description: Although much effort has been expended on studying many sites of social memory, little attention has been directed at the media’s work of memory, especially in post-colonial Africa. The media’s work of memory is important because of its social standing as a communicative and cultural institution, and because social memory is imbricated in processes of both collective identity formation and nation-building which partly shape patterns of economic distribution, recognition, and representation in society. It is in this context that this study shows how Zimbabwe’s The Sunday Mail and The Standard newspapers used social memory to construct the country’s national identity between 1999 and 2013 in the context of a socio-economic and political crisis for the country’s poly-racial, and poly-ethno-linguistic communities. The study also explores how these newspapers worked as memory sites through their construction of Zimbabwe’s national identity during the period under study. It achieves these tasks by analysing how these newspapers reported on such issues as Zimbabwe’s colonial history, the country’s narrative of decolonisation, the Gukurahundi narrative, the land reform process, elections and independence celebrations. The study takes a critical realist approach to qualitative research, and uses Fairclough and Fairclough’s (2012) method of political discourse analysis as well as Aristotle’s approach to rhetoric for a close reading of the sampled newspaper articles. It is informed by Nancy Fraser’s Theory of Justice, Chantal Mouffe’s Model of Agonistic Pluralism, and Jurgen Habermas’s Discourse Ethics Theory. The study concludes that these two newspapers actively use social memory to construct versions of national identity for specific socio-political and economic ends. Editorials and opinions from The Sunday Mail, which construct Zimbabwean-ness in nativist terms represent the hegemonic appropriation of social memory to construct a sense of Zimbabwean nationhood. In contrast, The Standard uses social memory to construct Zimbabwean-ness in modernist terms with citizenship as the core organising principle of belonging. The political discourse analysis of The Sunday Mail’s and The Standard’s evocation of social memory shows that the two newspapers reflect the tension between indigenist and universalist imaginaries of belonging in Zimbabwe. But the newspapers’ construction of belonging in Zimbabwe is informed by justice claims as seen from each of their political standpoints. As such, their respective definitions of Zimbabweans’ justice claims in terms of their political standpoints, also propose how those justice claims should be addressed and who stands to benefit from them.
- Full Text:
- Authors: Santos, Phillip
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/41753 , vital:25130
- Description: Although much effort has been expended on studying many sites of social memory, little attention has been directed at the media’s work of memory, especially in post-colonial Africa. The media’s work of memory is important because of its social standing as a communicative and cultural institution, and because social memory is imbricated in processes of both collective identity formation and nation-building which partly shape patterns of economic distribution, recognition, and representation in society. It is in this context that this study shows how Zimbabwe’s The Sunday Mail and The Standard newspapers used social memory to construct the country’s national identity between 1999 and 2013 in the context of a socio-economic and political crisis for the country’s poly-racial, and poly-ethno-linguistic communities. The study also explores how these newspapers worked as memory sites through their construction of Zimbabwe’s national identity during the period under study. It achieves these tasks by analysing how these newspapers reported on such issues as Zimbabwe’s colonial history, the country’s narrative of decolonisation, the Gukurahundi narrative, the land reform process, elections and independence celebrations. The study takes a critical realist approach to qualitative research, and uses Fairclough and Fairclough’s (2012) method of political discourse analysis as well as Aristotle’s approach to rhetoric for a close reading of the sampled newspaper articles. It is informed by Nancy Fraser’s Theory of Justice, Chantal Mouffe’s Model of Agonistic Pluralism, and Jurgen Habermas’s Discourse Ethics Theory. The study concludes that these two newspapers actively use social memory to construct versions of national identity for specific socio-political and economic ends. Editorials and opinions from The Sunday Mail, which construct Zimbabwean-ness in nativist terms represent the hegemonic appropriation of social memory to construct a sense of Zimbabwean nationhood. In contrast, The Standard uses social memory to construct Zimbabwean-ness in modernist terms with citizenship as the core organising principle of belonging. The political discourse analysis of The Sunday Mail’s and The Standard’s evocation of social memory shows that the two newspapers reflect the tension between indigenist and universalist imaginaries of belonging in Zimbabwe. But the newspapers’ construction of belonging in Zimbabwe is informed by justice claims as seen from each of their political standpoints. As such, their respective definitions of Zimbabweans’ justice claims in terms of their political standpoints, also propose how those justice claims should be addressed and who stands to benefit from them.
- Full Text:
The epidemiology of African horse sickness in the Eastern Cape, South Africa
- Authors: Riddin, Megan Amy
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64460 , vital:28546
- Description: Expected release date-May 2019
- Full Text:
- Authors: Riddin, Megan Amy
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64460 , vital:28546
- Description: Expected release date-May 2019
- Full Text:
A critical realist dialectical understanding of learning pathways associated with two scarce skill environmental occupations within a transitioning systems frame
- Authors: Ramsarup, Presha
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5937 , vital:20992
- Description: Policy, environmental, social and economic factors are all driving South Africa's transition to sustainable development and a greener economy. Various policies have been developed to foster sustainable development in the post-apartheid era in South Africa (i.e. since 1994) and there are various projections on potential job creation for a green economy. However, there is a problem related to both the achievement of sustainable development and green economy objectives: South Africa is said to lack adequately qualified people to implement these goals resulting in what is termed 'scarce skills' in the environmental and sustainable development sector. This problem has, in turn, prompted various skills development studies in the environmental sector, including a national Environmental Sector Skills Plan produced in 2010. All these studies point to a reactive skills development system that provides inadequate learning pathways for existing and newly emerging green occupations, which provided the impetus for a more proactive, transformative praxis oriented system of skills development that supports environmental learning pathways in South Africa. A second problem is that the concept of 'learning pathway' is poorly defined in the South African environmental education and wider education and training policy context. This term is often used in policy discourse within the notion of 'seamless learning pathways' and is only vaguely defined. This study set out to investigate selected occupationally directed environmental learning pathways in the South African National Qualifications Framework (NQF) and green transitioning context. In attempting to characterise the nature of the environmental pathway, the study utilised critical realist metatheory which serves as an underlabourer for domain specific theory of transitioning societies and systems, life-course transitions and career development. This theoretical work allowed the characterisation of environmental learning pathways as educational and occupational progression. The study investigated the nature of learning and work transitions across the life- course of selected environmental professionals in two key occupational categories - environmental engineer and environmental scientist - both of which have been defined as scarce skills in South Africa. This enabled a nuanced examination of the formation of what emerged as 'boundaryless' career stories of professionals engaged in these two occupations. The study also sought to engage with a methodological problem in learning pathways research, notably that studies are generally framed either at the micro level career story, emphasising agency of individuals (voluntarism), or at the policy level, emphasising structural aspects of the skills development system (determinism). This study sought to bridge the macro-micro problem drawing on critical realist retroductive analysis; this facilitated the shift from a focus on events and experiences that can be empirically observed (captured in case study approaches) to the causal mechanisms influencing environmental learning pathways in these two scarce skill occupations (discussed and analysed using dialectical critical realism), shedding light on how systemic and structural dynamics and mechanisms shape and influence the emergence of learning pathways as experienced in scarce skill occupations in the environmental sector. The opening chapters of the thesis provide an historical view of how the South African education and training system, itself in a transitioning process, has had to grapple with how to respond to and meaningfully take up the new emerging environmental / sustainable development mandate, which is increasingly framed within a multi-levelled transitioning social-ecological system perspective in post-apartheid South Africa. These transitioning systems are shaped by substantive policy imperatives for societal transformation, social justice, sustainable development and equity. Since 1994, various transformations have been taking place, often in paradoxical forms, in both the environmental and educational sectors, shaping a complex multi-levelled transitioning systems perspective for the study. This background work on transitioning systems provides the foundation for the first data chapter, which provides a descriptive outline of key supply side systemic elements as these pertain to environmental learning pathways more broadly (qualifications; occupational framing; career systems; sector skills planning). It also points to the lack of adequate mechanisms for analysing demand for environmental occupations, and highlights some of the contradictions in the supply- demand relation as these pertain to newly emerging environmental occupations. This helps to explain the empirical findings of previous environmental sector studies on the slow and reactive defining of environmental education and training for environmental occupations within the transforming education and training system in South Africa. The next two chapters, using case-based qualitative data, present the analysis of the two scarce skill occupations investigated - environmental engineer and environmental scientist. These chapters outline the dominant institutional educational pathway and the key supply platforms that support these pathways (career guidance; qualifications, occupational framings, skills planning) and the learning and work transitions of professionals within the occupation. The chapters highlight the factors and causal mechanisms influencing these learning pathways and thus provide insight into the multi-level dynamics that underpin learning pathways. The final chapter uses dialectical critical realism to outline generative mechanisms influencing the construction of the learning pathways. It also highlights key absences that are shaping the emergence (or not) of environmental learning pathways, thus pointing to opportunities for how the NQF might respond to the two scarce skill occupations under study, and to the emergence of environmental learning pathways more broadly within the framework of society-in-transition. Through this, the study links the career stories as analysed within the framework of learning pathways and skills system transitioning literature, to generative mechanisms and system development elements. The study concludes with providing occupational and systemic insights into absences and disjunctures that characterise the emergence (or not) of occupationally oriented environmental learning pathways. It also provides insight into what leads to these absences, and how they are kept in place and suggests possibilities and openings for transformative praxis within a multi-levelled transitioning system framework. The study makes the following contributions: At a theoretical level, the study has shown that environmental learning pathways need to be viewed as a complex phenomenon that is emergent in open systems and constituted by dialectically interdependent planes. A deeper understanding of environmental learning pathways is driven by both educational and occupational progression. It utilises key contemporary ideas around learning and work transitions but links them to the broader analyses of transitioning societies influencing the environmental sector, indicating the significance of how environmental education and training system development is situated within the wider transitioning process oriented towards social-ecological sustainability, social justice and greener economies. This study has further identified green skills as an important focus in research work on transitioning societies. At a methodological level, the study has shown how macro-micro and laminated system research can be useful in studying transitioning systems. As a laminated systems study with a focus on transitioning societies, it provides a baseline for further systems study on green work and green skills. At a practical level, the study has made actual contributions to the conceptualisation of learning pathways in the South African NQF context, to building and informing future green skill developments in the South African post-school system, the environmental sector and to informing conceptualising in the emergent Green Skills project.
- Full Text:
- Authors: Ramsarup, Presha
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5937 , vital:20992
- Description: Policy, environmental, social and economic factors are all driving South Africa's transition to sustainable development and a greener economy. Various policies have been developed to foster sustainable development in the post-apartheid era in South Africa (i.e. since 1994) and there are various projections on potential job creation for a green economy. However, there is a problem related to both the achievement of sustainable development and green economy objectives: South Africa is said to lack adequately qualified people to implement these goals resulting in what is termed 'scarce skills' in the environmental and sustainable development sector. This problem has, in turn, prompted various skills development studies in the environmental sector, including a national Environmental Sector Skills Plan produced in 2010. All these studies point to a reactive skills development system that provides inadequate learning pathways for existing and newly emerging green occupations, which provided the impetus for a more proactive, transformative praxis oriented system of skills development that supports environmental learning pathways in South Africa. A second problem is that the concept of 'learning pathway' is poorly defined in the South African environmental education and wider education and training policy context. This term is often used in policy discourse within the notion of 'seamless learning pathways' and is only vaguely defined. This study set out to investigate selected occupationally directed environmental learning pathways in the South African National Qualifications Framework (NQF) and green transitioning context. In attempting to characterise the nature of the environmental pathway, the study utilised critical realist metatheory which serves as an underlabourer for domain specific theory of transitioning societies and systems, life-course transitions and career development. This theoretical work allowed the characterisation of environmental learning pathways as educational and occupational progression. The study investigated the nature of learning and work transitions across the life- course of selected environmental professionals in two key occupational categories - environmental engineer and environmental scientist - both of which have been defined as scarce skills in South Africa. This enabled a nuanced examination of the formation of what emerged as 'boundaryless' career stories of professionals engaged in these two occupations. The study also sought to engage with a methodological problem in learning pathways research, notably that studies are generally framed either at the micro level career story, emphasising agency of individuals (voluntarism), or at the policy level, emphasising structural aspects of the skills development system (determinism). This study sought to bridge the macro-micro problem drawing on critical realist retroductive analysis; this facilitated the shift from a focus on events and experiences that can be empirically observed (captured in case study approaches) to the causal mechanisms influencing environmental learning pathways in these two scarce skill occupations (discussed and analysed using dialectical critical realism), shedding light on how systemic and structural dynamics and mechanisms shape and influence the emergence of learning pathways as experienced in scarce skill occupations in the environmental sector. The opening chapters of the thesis provide an historical view of how the South African education and training system, itself in a transitioning process, has had to grapple with how to respond to and meaningfully take up the new emerging environmental / sustainable development mandate, which is increasingly framed within a multi-levelled transitioning social-ecological system perspective in post-apartheid South Africa. These transitioning systems are shaped by substantive policy imperatives for societal transformation, social justice, sustainable development and equity. Since 1994, various transformations have been taking place, often in paradoxical forms, in both the environmental and educational sectors, shaping a complex multi-levelled transitioning systems perspective for the study. This background work on transitioning systems provides the foundation for the first data chapter, which provides a descriptive outline of key supply side systemic elements as these pertain to environmental learning pathways more broadly (qualifications; occupational framing; career systems; sector skills planning). It also points to the lack of adequate mechanisms for analysing demand for environmental occupations, and highlights some of the contradictions in the supply- demand relation as these pertain to newly emerging environmental occupations. This helps to explain the empirical findings of previous environmental sector studies on the slow and reactive defining of environmental education and training for environmental occupations within the transforming education and training system in South Africa. The next two chapters, using case-based qualitative data, present the analysis of the two scarce skill occupations investigated - environmental engineer and environmental scientist. These chapters outline the dominant institutional educational pathway and the key supply platforms that support these pathways (career guidance; qualifications, occupational framings, skills planning) and the learning and work transitions of professionals within the occupation. The chapters highlight the factors and causal mechanisms influencing these learning pathways and thus provide insight into the multi-level dynamics that underpin learning pathways. The final chapter uses dialectical critical realism to outline generative mechanisms influencing the construction of the learning pathways. It also highlights key absences that are shaping the emergence (or not) of environmental learning pathways, thus pointing to opportunities for how the NQF might respond to the two scarce skill occupations under study, and to the emergence of environmental learning pathways more broadly within the framework of society-in-transition. Through this, the study links the career stories as analysed within the framework of learning pathways and skills system transitioning literature, to generative mechanisms and system development elements. The study concludes with providing occupational and systemic insights into absences and disjunctures that characterise the emergence (or not) of occupationally oriented environmental learning pathways. It also provides insight into what leads to these absences, and how they are kept in place and suggests possibilities and openings for transformative praxis within a multi-levelled transitioning system framework. The study makes the following contributions: At a theoretical level, the study has shown that environmental learning pathways need to be viewed as a complex phenomenon that is emergent in open systems and constituted by dialectically interdependent planes. A deeper understanding of environmental learning pathways is driven by both educational and occupational progression. It utilises key contemporary ideas around learning and work transitions but links them to the broader analyses of transitioning societies influencing the environmental sector, indicating the significance of how environmental education and training system development is situated within the wider transitioning process oriented towards social-ecological sustainability, social justice and greener economies. This study has further identified green skills as an important focus in research work on transitioning societies. At a methodological level, the study has shown how macro-micro and laminated system research can be useful in studying transitioning systems. As a laminated systems study with a focus on transitioning societies, it provides a baseline for further systems study on green work and green skills. At a practical level, the study has made actual contributions to the conceptualisation of learning pathways in the South African NQF context, to building and informing future green skill developments in the South African post-school system, the environmental sector and to informing conceptualising in the emergent Green Skills project.
- Full Text:
Genetic diversity, evolutionary relationships and conservation of southern African Labeo fishes in relation to water management
- Authors: Ramoejane, Mpho
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5209 , vital:20786
- Description: Labeo spp. are large, herbivorous fishes that are important components of aquatic ecosystems and are a high conservation priority in South Africa. This thesis contributes to determination of conservation priorities for Labeo umbratus (Smith 1841) by resolving the taxonomic status of this species in the evolutionary context of southern African Labeo spp., assessing the presence of unique lineages in historically isolated river basins, and assessing the threat of intra- and interspecific hybridisation associated with introductions. Phylogenetic analyses of five DNA sequence data sets (cytochrome c oxidase subunit I gene [COI], cytochrome b gene [Cyt b], Recombination activating gene 1 [Rag1], COI+Rag1 and COI+Cyt b+Rag1) showed that the Labeo umbratus group (sensu Reid, 1985), which comprises the species Labeo umbratus, Labeo capensis (Smith 1841), Labeo seeberi Gilchrist and Thompson 1911 and Labeo rubromaculatus Gilchrist and Thompson 1913, is monophyletic, morphologically distinct and geographically disjunct from other African Labeo spp. groups except in the Tugela River system were L. rubromaculatus co-occurs with Labeo molybdinus Du Plessis 1963. Phylogeographic analysis of mitochondrial DNA (Cyt b) sequence data demonstrated that the populations of the L. umbratus from the Orange and the southward-flowing river systems are reciprocally monophyletic and were identified as evolutionary significant units. The populations in the southward-flowing river systems were further divided into southwestern (Gourits and Gamtoos) and southeastern (Sundays, Bushmans, Great Fish, Keiskamma, Buffalo and Nahoon) polyp hyletic sublineages. Four management units (Gourits Basin; Gamtoos Basin; Sundays+Bushmans+Great Fish River Basins; and Keiskamma+Buffalo+Nahoon River Basin) were not reciprocally monophyletic but were proposed on the basis of containing unique haplotype frequencies for conservation purposes. To evaluate the threat of hybridisation to the genetic integrity of L. umbratus, the occurrence of Labeo umbratus x L. capensis hybrids was investigated using mtDNA Cyt b and nDNA S7 intron sequence data and morphological data. Genetic evidence for interspecific hybridisation was detected for populations in two impoundments, Hardap Dam (Orange River Basin) and Darlington Dam (Sundays River Basin, Eastern Cape, South Africa). Some putative hybrids were identifiable morphologically on account of intermediacy between the parental species in meristic and morphometric characters. Translocation via direct stocking (Hardap Dam) or via an inter-basin water transfer scheme (Darlington Dam) was identified as a driver for hybridisation. Introductions associated with an inter-basin water transfer scheme has resulted in introgression between the previously isolated Orange River and southern lineages of L. umbratus. Further translocation of fish from these affected areas to non-contaminated river systems and impoundments such as Kat River (Great Fish River) and Slagboom (Sundays River) should be avoided.
- Full Text:
- Authors: Ramoejane, Mpho
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5209 , vital:20786
- Description: Labeo spp. are large, herbivorous fishes that are important components of aquatic ecosystems and are a high conservation priority in South Africa. This thesis contributes to determination of conservation priorities for Labeo umbratus (Smith 1841) by resolving the taxonomic status of this species in the evolutionary context of southern African Labeo spp., assessing the presence of unique lineages in historically isolated river basins, and assessing the threat of intra- and interspecific hybridisation associated with introductions. Phylogenetic analyses of five DNA sequence data sets (cytochrome c oxidase subunit I gene [COI], cytochrome b gene [Cyt b], Recombination activating gene 1 [Rag1], COI+Rag1 and COI+Cyt b+Rag1) showed that the Labeo umbratus group (sensu Reid, 1985), which comprises the species Labeo umbratus, Labeo capensis (Smith 1841), Labeo seeberi Gilchrist and Thompson 1911 and Labeo rubromaculatus Gilchrist and Thompson 1913, is monophyletic, morphologically distinct and geographically disjunct from other African Labeo spp. groups except in the Tugela River system were L. rubromaculatus co-occurs with Labeo molybdinus Du Plessis 1963. Phylogeographic analysis of mitochondrial DNA (Cyt b) sequence data demonstrated that the populations of the L. umbratus from the Orange and the southward-flowing river systems are reciprocally monophyletic and were identified as evolutionary significant units. The populations in the southward-flowing river systems were further divided into southwestern (Gourits and Gamtoos) and southeastern (Sundays, Bushmans, Great Fish, Keiskamma, Buffalo and Nahoon) polyp hyletic sublineages. Four management units (Gourits Basin; Gamtoos Basin; Sundays+Bushmans+Great Fish River Basins; and Keiskamma+Buffalo+Nahoon River Basin) were not reciprocally monophyletic but were proposed on the basis of containing unique haplotype frequencies for conservation purposes. To evaluate the threat of hybridisation to the genetic integrity of L. umbratus, the occurrence of Labeo umbratus x L. capensis hybrids was investigated using mtDNA Cyt b and nDNA S7 intron sequence data and morphological data. Genetic evidence for interspecific hybridisation was detected for populations in two impoundments, Hardap Dam (Orange River Basin) and Darlington Dam (Sundays River Basin, Eastern Cape, South Africa). Some putative hybrids were identifiable morphologically on account of intermediacy between the parental species in meristic and morphometric characters. Translocation via direct stocking (Hardap Dam) or via an inter-basin water transfer scheme (Darlington Dam) was identified as a driver for hybridisation. Introductions associated with an inter-basin water transfer scheme has resulted in introgression between the previously isolated Orange River and southern lineages of L. umbratus. Further translocation of fish from these affected areas to non-contaminated river systems and impoundments such as Kat River (Great Fish River) and Slagboom (Sundays River) should be avoided.
- Full Text:
Development and assessment of ketoconazole intravaginal thermosetting hydrogel formulations
- Authors: Ramanah, Ashmita
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5198 , vital:20785
- Description: Imidazole compounds are commonly used as antifungal therapies and ketoconazole was the first broad spectrum orally active azole identified and registered. However, the risks of hepatotoxicity and drug interactions following systemic delivery and absorption of ketoconazole outweigh the therapeutic benefits and ketoconazole was therefore discontinued as first line systemic antifungal therapy in many countries. Although not yet banned in South Africa, the South African Medicine Formulary has ceased to recommend the use of ketoconazole for systemic treatment. Topical use of ketoconazole is, however, regarded as safe following extensive human use as low systemic absorption occurs following topical administration. Vulvo-vaginal candidiasis is a yeast infection that affects a large number of women, some of whom present with several infections annually. The topical treatment options for vulvo-vaginal candidiasis include the use of vaginal tablets, capsules, ovules and creams administered as a single dose or one to three times daily for three to fourteen days either alone or in combination with another dosage form depending on the regimen. Administration of the dose nightly is recommended for most vaginal creams and ovule formulation due to leakage and the uncomfortable feel of the dosage form if administered during the day. A thermosetting gel that remains in the vagina following administration and prolongs the release of ketoconazole from a once daily dose would be a useful addition to the arsenal for intra-vaginal antifungal therapy. Thermosetting gels would be more comfortable to administer as the gel would set in a form similar to naturally occurring mucous in the vagina and, if formulated with a low pH, irritation of the sensitive and fissured tissue would be minimised. A further benefit would be that once set the gel would loosely take on the anatomical shape of the vagina. A simple, precise, accurate, reproducible and sensitive stability-indicating reversed phase-high performance liquid chromatographic method using ultraviolet detection for the quantitation of ketoconazole was developed and validated. The method was specific and was applied to the determination of ketoconazole in commercial and experimental formulations in addition to samples from degradation studies and in vitro release testing. Product performance characteristics of commercial products were investigated with the goal to provide a strategy for the development of a novel intra vaginal gel in the shortest possible time. Characterisation of Xolegel®, Kez® shampoo and Ketazol® cream included an evaluation of pH, viscosity and assay, in addition to spectroscopic and thermal analysis, to identify ideal characteristics of topical products that could be used as targets during formulation development of the gel. An in vitro release method was developed and validated for precision and accuracy and the in vitro release profiles of commercial ketoconazole products were compared using analysis of variance, model dependent and independent approaches. Ketoconazole release data from test gel manufactured during formulation development were investigated to obtain information about the relationship between formulation content and drug release. Poloxamers marketed as Pluronic® and Lutrol® are synthetic non-ionic tri-block copolymers that consist of hydrophobic propylene oxide and hydrophilic polyethylene oxide blocks, which in solution interact to exhibit thermo-reversible behaviour. In situ forming hydrogels consisting of poloxamers, more specifically poloxamer 407, are activated following a temperature stimulus and undergo a sol to gel transition. This approach was used to produce a thermosetting vaginal gel that would exhibit a long residence time in the vagina with an associated enhancement of therapeutic efficacy. Ketoconazole- excipient compatibility was investigated during preformulation studies using spectroscopic and thermal analysis to enable the selection of excipients best suited for the production of a novel dosage form prior to formulation development activities. No obvious interactions between ketoconazole and excipient were observed and ketoconazole was found in an amorphous form when in combination with polysorbate 80 and poloxamers. A two-level factorial design was used to produce solvent systems with different amounts of polysorbate 80, citric acid and ethanol to identify a vehicle in which ketoconazole exhibited optimum solubility and at a pH that would be least irritating to the vaginal mucosa with a low content of excipients. The optimised vehicle consisted of 4% m/v citric acid, 1.5% v/v polysorbate 80 and 9.5% v/v ethanol made up to 50 g with citrate-phosphate buffer adjusted to pH 5.0, resulted in a vehicle of pH of 3.5 in which 71.41 mg of ketoconazole was dissolved per mL. A Central Composite Design was used to evaluate compositions for the modulation of viscosity of the thermosetting dosage form such that it was a liquid at 22 °C that rapidly formed a stiff gel when heated to 37 °C (intra-vaginal temperature) using different amounts of the poloxamer grades 407, 188 and 237. Thermosetting gels containing 2% m/v ketoconazole were manufactured using specifications generated using the Central Composite Design and the viscosity at 22 °C and 37 °C, solution to gel transition time, potency and ketoconazole release at 24, 48 and 72 hours investigated. Contour and three-dimensional response surface plots and mathematical relationships with target ranges set for responses were identified and with the aid of Central Composite Design the optimisation of a desirable thermosetting gel was achieved. The optimised composition included 16% m/v poloxamer 407, 10% m/v poloxamer 188 and 6% m/v poloxamer 237 in the gel that was used as the basis for further optimisation studies. The low ketoconazole release for ketoconazole observed indicated that the poloxamers had formed a gel matrix that sustained the release of ketoconazole and would therefore ensure that once daily administration of the gel was possible. The sol-gel transition test may be used as a simple and cheap alternative to viscosity testing for thermosetting formulations when expensive viscometers and rheometers are unavailable and was successfully used for this purpose.Ketoconazole is photolabile and is prone to degradation in aqueous solutions. The hydrophobic core of micelles formed in these dosage forms are believed to shield ketoconazole molecules and improve stability in aqueous solutions and acidic gels. The thermosetting gel optimised for poloxamer content was subjected to a further Central Composite Design in which sodium metabisulphite content and vehicle pH were investigated. The length of storage was used as a numeric variable and storage condition as a categoric variable at two levels to monitor the stability of the gels. The formulations were investigated at sample times of 0, 1, 2, 4 and 8 weeks at 5 °C, 25 °C and 40 °C. The use of a Central Composite Design facilitated an understanding of the interactions between input variables and their impact on the responses analysed including ketoconazole content, release at 24, 48 and 72 hours, gel pH and viscosity at 22 °C and 37 °C. Design of Experiments may be used as a rapid cost effective tool for an overall assessment of the stability of novel topical dosage forms. However, a more thorough assessment of stability may be required for product registration. Ketoconazole was found to be unstable in the acidic thermosetting gels despite the addition of antioxidant. The gels in liquid form at 5 °C and 25 °C have a low number of micelles for ketoconazole incorporation and therefore additional optimisation studies would be required to enhance the shelf-life of this product.
- Full Text:
- Authors: Ramanah, Ashmita
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/5198 , vital:20785
- Description: Imidazole compounds are commonly used as antifungal therapies and ketoconazole was the first broad spectrum orally active azole identified and registered. However, the risks of hepatotoxicity and drug interactions following systemic delivery and absorption of ketoconazole outweigh the therapeutic benefits and ketoconazole was therefore discontinued as first line systemic antifungal therapy in many countries. Although not yet banned in South Africa, the South African Medicine Formulary has ceased to recommend the use of ketoconazole for systemic treatment. Topical use of ketoconazole is, however, regarded as safe following extensive human use as low systemic absorption occurs following topical administration. Vulvo-vaginal candidiasis is a yeast infection that affects a large number of women, some of whom present with several infections annually. The topical treatment options for vulvo-vaginal candidiasis include the use of vaginal tablets, capsules, ovules and creams administered as a single dose or one to three times daily for three to fourteen days either alone or in combination with another dosage form depending on the regimen. Administration of the dose nightly is recommended for most vaginal creams and ovule formulation due to leakage and the uncomfortable feel of the dosage form if administered during the day. A thermosetting gel that remains in the vagina following administration and prolongs the release of ketoconazole from a once daily dose would be a useful addition to the arsenal for intra-vaginal antifungal therapy. Thermosetting gels would be more comfortable to administer as the gel would set in a form similar to naturally occurring mucous in the vagina and, if formulated with a low pH, irritation of the sensitive and fissured tissue would be minimised. A further benefit would be that once set the gel would loosely take on the anatomical shape of the vagina. A simple, precise, accurate, reproducible and sensitive stability-indicating reversed phase-high performance liquid chromatographic method using ultraviolet detection for the quantitation of ketoconazole was developed and validated. The method was specific and was applied to the determination of ketoconazole in commercial and experimental formulations in addition to samples from degradation studies and in vitro release testing. Product performance characteristics of commercial products were investigated with the goal to provide a strategy for the development of a novel intra vaginal gel in the shortest possible time. Characterisation of Xolegel®, Kez® shampoo and Ketazol® cream included an evaluation of pH, viscosity and assay, in addition to spectroscopic and thermal analysis, to identify ideal characteristics of topical products that could be used as targets during formulation development of the gel. An in vitro release method was developed and validated for precision and accuracy and the in vitro release profiles of commercial ketoconazole products were compared using analysis of variance, model dependent and independent approaches. Ketoconazole release data from test gel manufactured during formulation development were investigated to obtain information about the relationship between formulation content and drug release. Poloxamers marketed as Pluronic® and Lutrol® are synthetic non-ionic tri-block copolymers that consist of hydrophobic propylene oxide and hydrophilic polyethylene oxide blocks, which in solution interact to exhibit thermo-reversible behaviour. In situ forming hydrogels consisting of poloxamers, more specifically poloxamer 407, are activated following a temperature stimulus and undergo a sol to gel transition. This approach was used to produce a thermosetting vaginal gel that would exhibit a long residence time in the vagina with an associated enhancement of therapeutic efficacy. Ketoconazole- excipient compatibility was investigated during preformulation studies using spectroscopic and thermal analysis to enable the selection of excipients best suited for the production of a novel dosage form prior to formulation development activities. No obvious interactions between ketoconazole and excipient were observed and ketoconazole was found in an amorphous form when in combination with polysorbate 80 and poloxamers. A two-level factorial design was used to produce solvent systems with different amounts of polysorbate 80, citric acid and ethanol to identify a vehicle in which ketoconazole exhibited optimum solubility and at a pH that would be least irritating to the vaginal mucosa with a low content of excipients. The optimised vehicle consisted of 4% m/v citric acid, 1.5% v/v polysorbate 80 and 9.5% v/v ethanol made up to 50 g with citrate-phosphate buffer adjusted to pH 5.0, resulted in a vehicle of pH of 3.5 in which 71.41 mg of ketoconazole was dissolved per mL. A Central Composite Design was used to evaluate compositions for the modulation of viscosity of the thermosetting dosage form such that it was a liquid at 22 °C that rapidly formed a stiff gel when heated to 37 °C (intra-vaginal temperature) using different amounts of the poloxamer grades 407, 188 and 237. Thermosetting gels containing 2% m/v ketoconazole were manufactured using specifications generated using the Central Composite Design and the viscosity at 22 °C and 37 °C, solution to gel transition time, potency and ketoconazole release at 24, 48 and 72 hours investigated. Contour and three-dimensional response surface plots and mathematical relationships with target ranges set for responses were identified and with the aid of Central Composite Design the optimisation of a desirable thermosetting gel was achieved. The optimised composition included 16% m/v poloxamer 407, 10% m/v poloxamer 188 and 6% m/v poloxamer 237 in the gel that was used as the basis for further optimisation studies. The low ketoconazole release for ketoconazole observed indicated that the poloxamers had formed a gel matrix that sustained the release of ketoconazole and would therefore ensure that once daily administration of the gel was possible. The sol-gel transition test may be used as a simple and cheap alternative to viscosity testing for thermosetting formulations when expensive viscometers and rheometers are unavailable and was successfully used for this purpose.Ketoconazole is photolabile and is prone to degradation in aqueous solutions. The hydrophobic core of micelles formed in these dosage forms are believed to shield ketoconazole molecules and improve stability in aqueous solutions and acidic gels. The thermosetting gel optimised for poloxamer content was subjected to a further Central Composite Design in which sodium metabisulphite content and vehicle pH were investigated. The length of storage was used as a numeric variable and storage condition as a categoric variable at two levels to monitor the stability of the gels. The formulations were investigated at sample times of 0, 1, 2, 4 and 8 weeks at 5 °C, 25 °C and 40 °C. The use of a Central Composite Design facilitated an understanding of the interactions between input variables and their impact on the responses analysed including ketoconazole content, release at 24, 48 and 72 hours, gel pH and viscosity at 22 °C and 37 °C. Design of Experiments may be used as a rapid cost effective tool for an overall assessment of the stability of novel topical dosage forms. However, a more thorough assessment of stability may be required for product registration. Ketoconazole was found to be unstable in the acidic thermosetting gels despite the addition of antioxidant. The gels in liquid form at 5 °C and 25 °C have a low number of micelles for ketoconazole incorporation and therefore additional optimisation studies would be required to enhance the shelf-life of this product.
- Full Text:
Geomorphological connectivity and sensitivity examined in a recently degraded gravel-bed stream: implications for river-floodplain rehabilitation
- Authors: Powell, Rebecca
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/53722 , vital:26313
- Description: The study of river complexity and sensitivity to future human land-use activities and climate change is a fast growing field within the discipline of fluvial geomorphology. Associated with this is a need to improve river rehabilitation and catchment management approach, design and effectiveness. This study aimed to investigate drivers of the recent geomorphological sensitivity of the Baviaanskloof River-floodplain, an upland system in South Africa, by integrating the concepts of geomorphological connectivity and Panarchy. The understanding generated was used to evaluate the approach of the State agency, Working for Wetlands (WfWet), to river-floodplain rehabilitation in the catchment.The concepts of geomorphological connectivity and Panarchy provide useful frameworks for understanding interactions between geomorphological processes and structure across scales of space and time. Geomorphological connectivity explains the degree to which water and sediment is linked in a river landscape, determined by the distribution of erosional and depositional landforms (Brierley et al. 2006; Fryirs et al. 2007a; Fryirs et al. 2007b). Panarchy attempts to explain lagged response to disturbances, non-linear interactions, and sudden shifts in system state, and has been applied largely to ecological systems. Panarchy theory, when combined with the concept of geomorphological connectivity, provides a guiding framework for understanding river complexity in greater depth. The first results chapter of this study investigated river long-term and recent geomorphological history, towards understanding the nature and timing of river geomorphological cycling between erosion and deposition. Optically Stimulated Luminescence dating of alluvial fan and floodplain sedimentary units was conducted, for analysis of river-floodplain long-term history (100s to 1 000s of years). Interviews with 11 local landowners, combined with analysis of historic aerial imagery and river-floodplain topographic surveys, provided a means of describing recent (last few decades) geomorphological dynamics. The results indicated that the Baviaanskloof is naturally a cut- and-fill landscape over scales of several hundred to thousands of years, characterized by the alternation between phases of high fluvial energy and alluvial fan expansion, and low energy conditions associated with floodplain accretion. Recent and widespread river-floodplain degradation was compressed into a short period of approximately 30 years, suggesting that one or more drivers have pushed the system beyond a threshold, resulting in increased water and sediment connectivity. The second results chapter investigated the role of human land-use activities and flooding frequency and magnitude, as drivers of recent river-floodplain degradation. Human impacts were investigated by describing land-use activities for the preceding 80 years, and relating these activities to changes in river-floodplain form and behavior. Temporal trends in flood events of different frequency and magnitude were investigated by analyzing rainfall data, integrated with landowner reports of flood-inducing rainfall magnitudes. The findings indicated that human land-use activities have been an important driver of recent river- floodplain degradation, through the enhancement of water and sediment connectivity across spatial scales of the catchment. Episodic and high magnitude floods synergized with human driven increased connectivity, precipitating stream power and geomorphological threshold breaches, resulting in a shift in river behaviour. The third results chapter investigated the influence of tributary-junction streams and fans on the geomorphological form, behavior and sensitivity of the Baviaanskloof River. Local- scale topographic impacts of tributary fans and streams were described using topographic surveys and geomorphological mapping techniques. Tributary streams form a major control on the behaviour of the river, by influencing the degree of coarse sediment connectivity with the main channel. Although tributary fans buffer the river from disturbances occurring in the wider catchment, they initiate topographic variations along the floodplain, influencing local-scale patterns of deposition and erosion along the river. The main river responds to water and sediment inputs from tributary junction streams by locally adjusting longitudinal slope, maintaining an overall constant slope of 0.0066 m/m. The response of the Baviaanskloof River to tributary junction fans and streams is however variable, and is fashioned by complex interactions between geomorphological and anthropogenic factors. The final two chapters of the thesis evaluate the findings of the study within the context of river-floodplain rehabilitation approaches in South Africa, and within the theoretical, philosophical and methodological context of the research. The first of these two chapters evaluates the approach of the WfWet programme to river-floodplain rehabilitation in the Baviaanskloof. The chapter indicates that the present practice of WfWet is to reinstate a pre-degradation state, which is not suited to the Baviaanskloof River-floodplain, since the river-floodplain has passed a geomorphological threshold, resulting in a new set of interacting processes and landforms. The author presents a conceptual model illustrating the existence of geomorphological adaptive cycles interacting across spatial and temporal scales, thereby attempting to explain a river Panarchy specific to the Baviaanskloof. From this conceptual model, a hierarchical rehabilitation framework, targeting geomorphological processes and structure situated at different spatial and temporal scales of the landscape is suggested. The final chapter discusses the implications of integrating the concepts of geomorphological connectivity and river Panarchy theory in studies of river complexity and sensitivity to geomorphological change. The author suggests that there is scope for further investigation of the application of the two concepts within the discipline of fluvial geomorphology, particularly with regard to developing quantitative approaches to measuring and describing connectivity and Panarchy.
- Full Text:
- Authors: Powell, Rebecca
- Date: 2017
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/53722 , vital:26313
- Description: The study of river complexity and sensitivity to future human land-use activities and climate change is a fast growing field within the discipline of fluvial geomorphology. Associated with this is a need to improve river rehabilitation and catchment management approach, design and effectiveness. This study aimed to investigate drivers of the recent geomorphological sensitivity of the Baviaanskloof River-floodplain, an upland system in South Africa, by integrating the concepts of geomorphological connectivity and Panarchy. The understanding generated was used to evaluate the approach of the State agency, Working for Wetlands (WfWet), to river-floodplain rehabilitation in the catchment.The concepts of geomorphological connectivity and Panarchy provide useful frameworks for understanding interactions between geomorphological processes and structure across scales of space and time. Geomorphological connectivity explains the degree to which water and sediment is linked in a river landscape, determined by the distribution of erosional and depositional landforms (Brierley et al. 2006; Fryirs et al. 2007a; Fryirs et al. 2007b). Panarchy attempts to explain lagged response to disturbances, non-linear interactions, and sudden shifts in system state, and has been applied largely to ecological systems. Panarchy theory, when combined with the concept of geomorphological connectivity, provides a guiding framework for understanding river complexity in greater depth. The first results chapter of this study investigated river long-term and recent geomorphological history, towards understanding the nature and timing of river geomorphological cycling between erosion and deposition. Optically Stimulated Luminescence dating of alluvial fan and floodplain sedimentary units was conducted, for analysis of river-floodplain long-term history (100s to 1 000s of years). Interviews with 11 local landowners, combined with analysis of historic aerial imagery and river-floodplain topographic surveys, provided a means of describing recent (last few decades) geomorphological dynamics. The results indicated that the Baviaanskloof is naturally a cut- and-fill landscape over scales of several hundred to thousands of years, characterized by the alternation between phases of high fluvial energy and alluvial fan expansion, and low energy conditions associated with floodplain accretion. Recent and widespread river-floodplain degradation was compressed into a short period of approximately 30 years, suggesting that one or more drivers have pushed the system beyond a threshold, resulting in increased water and sediment connectivity. The second results chapter investigated the role of human land-use activities and flooding frequency and magnitude, as drivers of recent river-floodplain degradation. Human impacts were investigated by describing land-use activities for the preceding 80 years, and relating these activities to changes in river-floodplain form and behavior. Temporal trends in flood events of different frequency and magnitude were investigated by analyzing rainfall data, integrated with landowner reports of flood-inducing rainfall magnitudes. The findings indicated that human land-use activities have been an important driver of recent river- floodplain degradation, through the enhancement of water and sediment connectivity across spatial scales of the catchment. Episodic and high magnitude floods synergized with human driven increased connectivity, precipitating stream power and geomorphological threshold breaches, resulting in a shift in river behaviour. The third results chapter investigated the influence of tributary-junction streams and fans on the geomorphological form, behavior and sensitivity of the Baviaanskloof River. Local- scale topographic impacts of tributary fans and streams were described using topographic surveys and geomorphological mapping techniques. Tributary streams form a major control on the behaviour of the river, by influencing the degree of coarse sediment connectivity with the main channel. Although tributary fans buffer the river from disturbances occurring in the wider catchment, they initiate topographic variations along the floodplain, influencing local-scale patterns of deposition and erosion along the river. The main river responds to water and sediment inputs from tributary junction streams by locally adjusting longitudinal slope, maintaining an overall constant slope of 0.0066 m/m. The response of the Baviaanskloof River to tributary junction fans and streams is however variable, and is fashioned by complex interactions between geomorphological and anthropogenic factors. The final two chapters of the thesis evaluate the findings of the study within the context of river-floodplain rehabilitation approaches in South Africa, and within the theoretical, philosophical and methodological context of the research. The first of these two chapters evaluates the approach of the WfWet programme to river-floodplain rehabilitation in the Baviaanskloof. The chapter indicates that the present practice of WfWet is to reinstate a pre-degradation state, which is not suited to the Baviaanskloof River-floodplain, since the river-floodplain has passed a geomorphological threshold, resulting in a new set of interacting processes and landforms. The author presents a conceptual model illustrating the existence of geomorphological adaptive cycles interacting across spatial and temporal scales, thereby attempting to explain a river Panarchy specific to the Baviaanskloof. From this conceptual model, a hierarchical rehabilitation framework, targeting geomorphological processes and structure situated at different spatial and temporal scales of the landscape is suggested. The final chapter discusses the implications of integrating the concepts of geomorphological connectivity and river Panarchy theory in studies of river complexity and sensitivity to geomorphological change. The author suggests that there is scope for further investigation of the application of the two concepts within the discipline of fluvial geomorphology, particularly with regard to developing quantitative approaches to measuring and describing connectivity and Panarchy.
- Full Text: