Towards a cost-efficient & standardised monitoring protocol for subtidal reef fish in the Agulhas ecoregion of South Africa
- Bernard, Anthony Thomas Firth
- Authors: Bernard, Anthony Thomas Firth
- Date: 2013
- Subjects: Reef fishes -- South Africa Reef fishes -- Monitoring--South Africa Fish stock assessment -- South Africa Coastal zone management -- South Africa Fish communities -- South Africa Marine parks and reserves -- South Africa Marine resources conservation -- South Africa Marine biodiversity conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5585 , http://hdl.handle.net/10962/d1001674
- Description: Under the growing demand for marine fish resources, and the apparent and expected impacts of global climate change, there is a need to conduct long-term monitoring (LTM) to ensure effective management of resources and conservation of biodiversity. However LTM programmes often suffer from design deficiencies and fail to achieve their objectives. These deficiencies stem from the fact that insufficient consideration is afforded to the design phase, with programmes selecting methods that are not suitable to address the objectives, or are not cost-efficient, compromising the sustainability of the LTM. To facilitate the establishment of LTM programmes along the southern coast of South Africa, background research needed to be conducted to identify which methods were most appropriate for LTM of reef fish. This study presents a detailed field-based assessment of the suitability and cost-efficiency of monitoring methods for long-term monitoring of reef fish in the Agulhas Ecoregion of South Africa. The approach adopted to identify the method, or suite of methods most suited for LTM, involved (i) the selection of methods considered suitable for LTM, (ii) the individual assessment and optimisation of method performance, and (iii) the comparative assessment of the fish community sampled by the different methods. The most suited method(s) were then identified as those that provide the most comprehensive assessment of the fish community and had the highest cost-efficiency. The research was conducted between January 2008 and 2011 in the Tsitsikamma and Table Mountain National Park (TNP and TMNP, respectively) marine protected areas (MPAs) within the Agulhas Ecoregion. The methods selected included fish traps (FT), controlled angling (CA), underwater visual census (UVC), remote underwater video (RUV), baited RUV (BRUV) and remotely operated vehicles (ROV). The individual assessment and optimisation was conducted with the FT, UVC, RUV and BRUV methods. The assessment of the FT method aimed to identify the optimal soak time, and whether or not the size of the funnel entrance to the trap affected the catch. The results identified that larger funnel entrances caught more fish and soak times of 80 minutes produced the highest catches per unit effort. However the data were highly variable and the method detected few of the species typical of the region. Fish traps were also associated with high levels of mortality of fish post-release. The assessment of UVC strip transect method involved directly comparing the precision of data collected by researchers and volunteers using a novel double-observer technique (paired-transects). The results showed considerable error in both the volunteers and researchers data, however the researchers produced significantly higher precision data, compared to the volunteers. The distinction between researchers and volunteers was not evident in the data for the dominant species of fish. For all observers, the abundance of a species in the sample had a significant influence on its detectability, with locally scarce or rare species poorly detected. UVC was able to sample the majority of species typical of reefs in the region, however it appeared plagued by observer and detectability biases. The assessments of RUV and BRUV were conducted simultaneously which enabled the assessment of the effect of bait on the observed fish community. In addition the optimal deployment time for both methods to maximise species richness and abundance was determined. The results showed that BRUV, and to a lesser degree RUV, were able to effectively survey the reef fish community for the region with a 50 minute and 35 minute deployment time, respectively. Baited remote underwater video was especially good at detecting the invertebrate and generalist carnivores, and cartilaginous species. On the other hand, RUV was more effective at surveying the microinvertebrate carnivores. Remote underwater video was characterised by higher data variability, compared to BRUV, and was ultimately considered a less cost-efficient monitoring method. Comparative methods assessments were conducted during two field experiments with the FT, UVC and BRUV methods in the TMNP MPA, and the FT, CA, UVC, RUV, BRUV and ROV methods compared in the TNP MPA. The objectives of the comparison were to investigate differences in the fish communities observed with the different methods, and to determine the power of the data to detect an annual 10% growth in the fish populations over a period of five years. The results from the method comparison were in turn used to conduct the cost-benefit analysis to determine the efficiency of the different methods at achieving monitoring objectives requiring population data from multiple trophic and functional groups with the community, and from species of fisheries importance. The results indicated that FT, CA and ROV were ineffective at monitoring the reef fish community, although CA appeared to provide valuable data for the dominant fisheries species. Both CA and FT required minimal initial investment however, the variability in the data translated into high annual monitoring costs, as the required sampling effort was great. The ROV required the highest initial investment and was identified as the least cost-efficient method. Underwater visual census was able to adequately survey the bony fish within the community, however it did not detect the cartilaginous species. Underwater visual census required a large initial investment and was not cost-efficient, as a many samples were required to account for the variability in the data. Remote underwater video provided a comprehensive assessment of the reef fish community, however it too was associated with high levels of variability in the data, compared to BRUV, reducing its cost-efficiency. BRUV provided the most comprehensive assessment of the reef fish community and was associated with the highest cost-efficiency to address the community and fisheries species monitoring objectives. During the course of this research stereo-BRUV has gained considerable support as an effective reef fish monitoring method. Although not tested during this research, stereo-BRUV is preferred to BRUV as it provides accurate data on the size of fish. However, the initial investment of stereo-BRUV is over three times that required for the BRUV. Although it is recommended that a baited video technique be used for LTM in the Agulhas Ecoregion, the choice between BRUV and stereo-BRUV will depend on the specific objectives of the programme and the available budget at the implementing agency.
- Full Text:
- Date Issued: 2013
- Authors: Bernard, Anthony Thomas Firth
- Date: 2013
- Subjects: Reef fishes -- South Africa Reef fishes -- Monitoring--South Africa Fish stock assessment -- South Africa Coastal zone management -- South Africa Fish communities -- South Africa Marine parks and reserves -- South Africa Marine resources conservation -- South Africa Marine biodiversity conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5585 , http://hdl.handle.net/10962/d1001674
- Description: Under the growing demand for marine fish resources, and the apparent and expected impacts of global climate change, there is a need to conduct long-term monitoring (LTM) to ensure effective management of resources and conservation of biodiversity. However LTM programmes often suffer from design deficiencies and fail to achieve their objectives. These deficiencies stem from the fact that insufficient consideration is afforded to the design phase, with programmes selecting methods that are not suitable to address the objectives, or are not cost-efficient, compromising the sustainability of the LTM. To facilitate the establishment of LTM programmes along the southern coast of South Africa, background research needed to be conducted to identify which methods were most appropriate for LTM of reef fish. This study presents a detailed field-based assessment of the suitability and cost-efficiency of monitoring methods for long-term monitoring of reef fish in the Agulhas Ecoregion of South Africa. The approach adopted to identify the method, or suite of methods most suited for LTM, involved (i) the selection of methods considered suitable for LTM, (ii) the individual assessment and optimisation of method performance, and (iii) the comparative assessment of the fish community sampled by the different methods. The most suited method(s) were then identified as those that provide the most comprehensive assessment of the fish community and had the highest cost-efficiency. The research was conducted between January 2008 and 2011 in the Tsitsikamma and Table Mountain National Park (TNP and TMNP, respectively) marine protected areas (MPAs) within the Agulhas Ecoregion. The methods selected included fish traps (FT), controlled angling (CA), underwater visual census (UVC), remote underwater video (RUV), baited RUV (BRUV) and remotely operated vehicles (ROV). The individual assessment and optimisation was conducted with the FT, UVC, RUV and BRUV methods. The assessment of the FT method aimed to identify the optimal soak time, and whether or not the size of the funnel entrance to the trap affected the catch. The results identified that larger funnel entrances caught more fish and soak times of 80 minutes produced the highest catches per unit effort. However the data were highly variable and the method detected few of the species typical of the region. Fish traps were also associated with high levels of mortality of fish post-release. The assessment of UVC strip transect method involved directly comparing the precision of data collected by researchers and volunteers using a novel double-observer technique (paired-transects). The results showed considerable error in both the volunteers and researchers data, however the researchers produced significantly higher precision data, compared to the volunteers. The distinction between researchers and volunteers was not evident in the data for the dominant species of fish. For all observers, the abundance of a species in the sample had a significant influence on its detectability, with locally scarce or rare species poorly detected. UVC was able to sample the majority of species typical of reefs in the region, however it appeared plagued by observer and detectability biases. The assessments of RUV and BRUV were conducted simultaneously which enabled the assessment of the effect of bait on the observed fish community. In addition the optimal deployment time for both methods to maximise species richness and abundance was determined. The results showed that BRUV, and to a lesser degree RUV, were able to effectively survey the reef fish community for the region with a 50 minute and 35 minute deployment time, respectively. Baited remote underwater video was especially good at detecting the invertebrate and generalist carnivores, and cartilaginous species. On the other hand, RUV was more effective at surveying the microinvertebrate carnivores. Remote underwater video was characterised by higher data variability, compared to BRUV, and was ultimately considered a less cost-efficient monitoring method. Comparative methods assessments were conducted during two field experiments with the FT, UVC and BRUV methods in the TMNP MPA, and the FT, CA, UVC, RUV, BRUV and ROV methods compared in the TNP MPA. The objectives of the comparison were to investigate differences in the fish communities observed with the different methods, and to determine the power of the data to detect an annual 10% growth in the fish populations over a period of five years. The results from the method comparison were in turn used to conduct the cost-benefit analysis to determine the efficiency of the different methods at achieving monitoring objectives requiring population data from multiple trophic and functional groups with the community, and from species of fisheries importance. The results indicated that FT, CA and ROV were ineffective at monitoring the reef fish community, although CA appeared to provide valuable data for the dominant fisheries species. Both CA and FT required minimal initial investment however, the variability in the data translated into high annual monitoring costs, as the required sampling effort was great. The ROV required the highest initial investment and was identified as the least cost-efficient method. Underwater visual census was able to adequately survey the bony fish within the community, however it did not detect the cartilaginous species. Underwater visual census required a large initial investment and was not cost-efficient, as a many samples were required to account for the variability in the data. Remote underwater video provided a comprehensive assessment of the reef fish community, however it too was associated with high levels of variability in the data, compared to BRUV, reducing its cost-efficiency. BRUV provided the most comprehensive assessment of the reef fish community and was associated with the highest cost-efficiency to address the community and fisheries species monitoring objectives. During the course of this research stereo-BRUV has gained considerable support as an effective reef fish monitoring method. Although not tested during this research, stereo-BRUV is preferred to BRUV as it provides accurate data on the size of fish. However, the initial investment of stereo-BRUV is over three times that required for the BRUV. Although it is recommended that a baited video technique be used for LTM in the Agulhas Ecoregion, the choice between BRUV and stereo-BRUV will depend on the specific objectives of the programme and the available budget at the implementing agency.
- Full Text:
- Date Issued: 2013
The use of Geographical Information Systems for the promotion of spatial cognition, spatial perspective taking and problem solving in school level geography
- Authors: Britz, Hendrina Wilhemina
- Date: 2013
- Subjects: Geography -- Study and teaching -- South Africa -- Port Elizabeth , Geographic information systems -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9579 , http://hdl.handle.net/10948/d1020298
- Description: A question asked at the United States of America (USA) National Council for Geographic Education (NCGE) conference in 1967, namely, what learning does GIS allow that other ways do not and whether teaching GIS at school level is worth the time and effort required to implement it, remains largely unanswered. Literature searches suggest that little more has been done since 1967 to investigate the effectiveness of GIS in education, or that there are any findings to suggest that GIS is worth the time and effort to implement in schools. Internationally the implementation of GIS software and geo-spatial data in schools has been slow, and South Africa is no exception. The main reasons given for slow implementation internationally have included lack of resources, lack of training and lack of time. The majority of secondary schools that offer Geography in the Port Elizabeth Education District, South Africa, teach GIS theory without the use of GIS software and geo-spatial data. The purpose of this research was to elicit the perceptions of secondary school level Geography teachers and learners of the benefits, barriers and obstacles to implementing GIS software and geo-spatial data as a teaching strategy. As a focused exercise to investigate what learning using GIS allows that other ways do not, this study also investigated whether using GIS as a teaching and learning strategy enables the promotion of learners spatial cognition, spatial perspective taking and problem solving abilities better than traditional methods do. The findings are viewed through the lens of developing Crystallized Intelligence (Gc), Spatial Intelligence (Gv) and Fluid Intelligence (Gf), respectively. The study followed a concurrent transformative mixed methods design with pre-post testing and the use of crossover experimental and control groups to generate both qualitative and quantitative data. Questionnaires aimed at all secondary Geography teachers in the Port Elizabeth Education District were used to assess how GIS is taught in their schools and to evaluate their perceptions of the benefits and barriers of implementing GIS software and geo-spatial data in the classroom. Four secondary school Geography teachers in four schools volunteered to take part in the experimental aspects of the study. Empirical data on the development of spatial cognition, spatial perspective taking, and problem solving were generated via pre- and post-tests in which the grade 11 Geography learners participated. Experimental and comparison groups of learners wrote four different types of pre- and post-tests where the experimental groups worked on GIS software with geo-spatial data while the comparison groups used traditional methods. Teacher interviews and learner interviews were also conducted to assess attitudes towards GIS software and geo-spatial data as a teaching strategy. The results from this aspect of the study mirrored the benefits and barriers to implementing GIS in schools recorded in international literature. However, and possibly more importantly, the empirical data generated by the learners revealed that GIS software and geo-spatial data do statistically significantly promote better spatial cognition (Crystallized Intelligence) and spatial perspective taking (Spatial Intelligence) than traditional methods do (i.e. using atlases, rulers and calculators). No improvement was found in the experimental groups‟ problem solving abilities. This report offers possible explanations and recommendations in terms of socio-cultural findings from other educational studies on the effects of exploratory talk on the development of Fluid Intelligence. Recommendations are made for the attention of curriculum developers, teachers, school principals, departmental officials and other educational stakeholders in terms of what is required for the successful implementation of GIS software and the use of geo-spatial data in secondary school Geography classes.
- Full Text:
- Date Issued: 2013
- Authors: Britz, Hendrina Wilhemina
- Date: 2013
- Subjects: Geography -- Study and teaching -- South Africa -- Port Elizabeth , Geographic information systems -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9579 , http://hdl.handle.net/10948/d1020298
- Description: A question asked at the United States of America (USA) National Council for Geographic Education (NCGE) conference in 1967, namely, what learning does GIS allow that other ways do not and whether teaching GIS at school level is worth the time and effort required to implement it, remains largely unanswered. Literature searches suggest that little more has been done since 1967 to investigate the effectiveness of GIS in education, or that there are any findings to suggest that GIS is worth the time and effort to implement in schools. Internationally the implementation of GIS software and geo-spatial data in schools has been slow, and South Africa is no exception. The main reasons given for slow implementation internationally have included lack of resources, lack of training and lack of time. The majority of secondary schools that offer Geography in the Port Elizabeth Education District, South Africa, teach GIS theory without the use of GIS software and geo-spatial data. The purpose of this research was to elicit the perceptions of secondary school level Geography teachers and learners of the benefits, barriers and obstacles to implementing GIS software and geo-spatial data as a teaching strategy. As a focused exercise to investigate what learning using GIS allows that other ways do not, this study also investigated whether using GIS as a teaching and learning strategy enables the promotion of learners spatial cognition, spatial perspective taking and problem solving abilities better than traditional methods do. The findings are viewed through the lens of developing Crystallized Intelligence (Gc), Spatial Intelligence (Gv) and Fluid Intelligence (Gf), respectively. The study followed a concurrent transformative mixed methods design with pre-post testing and the use of crossover experimental and control groups to generate both qualitative and quantitative data. Questionnaires aimed at all secondary Geography teachers in the Port Elizabeth Education District were used to assess how GIS is taught in their schools and to evaluate their perceptions of the benefits and barriers of implementing GIS software and geo-spatial data in the classroom. Four secondary school Geography teachers in four schools volunteered to take part in the experimental aspects of the study. Empirical data on the development of spatial cognition, spatial perspective taking, and problem solving were generated via pre- and post-tests in which the grade 11 Geography learners participated. Experimental and comparison groups of learners wrote four different types of pre- and post-tests where the experimental groups worked on GIS software with geo-spatial data while the comparison groups used traditional methods. Teacher interviews and learner interviews were also conducted to assess attitudes towards GIS software and geo-spatial data as a teaching strategy. The results from this aspect of the study mirrored the benefits and barriers to implementing GIS in schools recorded in international literature. However, and possibly more importantly, the empirical data generated by the learners revealed that GIS software and geo-spatial data do statistically significantly promote better spatial cognition (Crystallized Intelligence) and spatial perspective taking (Spatial Intelligence) than traditional methods do (i.e. using atlases, rulers and calculators). No improvement was found in the experimental groups‟ problem solving abilities. This report offers possible explanations and recommendations in terms of socio-cultural findings from other educational studies on the effects of exploratory talk on the development of Fluid Intelligence. Recommendations are made for the attention of curriculum developers, teachers, school principals, departmental officials and other educational stakeholders in terms of what is required for the successful implementation of GIS software and the use of geo-spatial data in secondary school Geography classes.
- Full Text:
- Date Issued: 2013
The adaptation of the 'Clinical Outcomes in Routine Evaluation-Outcome Measure' (CORE-OM) from English into a valid Xhosa measure of distress
- Authors: Campbell, Megan Michelle
- Date: 2013 , 2013-06-06
- Subjects: Psychometrics -- Research -- South Africa Psychology -- Mathematical models -- Research -- South Africa Psychological tests -- Research -- South Africa Mental health services -- Research -- South Africa Health services accessibility -- Research -- South Africa Language disorders -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2894 , http://hdl.handle.net/10962/d1001538
- Description: In South Africa access to mental healthcare resources is restricted for a number of reasons including language barriers that prevent suitable communication between mental healthcare professionals and African language speaking South Africans. The translation of psychometric tools into African languages has been identified as one method in improving access to psychological services for African language speakers. The Clinical Outcomes in Routine Evaluation - Outcome Measure (CORE-OM) has demonstrated its clinical utility within the United Kingdom (UK) National Healthcare Service (NHS) as a standardised psychotherapy outcome measure that evaluates the degree of psychological distress individuals present with at the start of psychotherapy treatment, and the degree of change that has been effected at the termination of therapy. A measure like the CORE-OM holds valuable clinical utility for the South African context. This thesis argues that the availability of a valid Xhosa version of the CORE-OM would allow for improved access to psychotherapy resources for Xhosa speaking individuals, and allow for the evaluation of the effectiveness of psychotherapy interventions conducted in Xhosa. The CORE-OM developers have provided a translation design and set of guidelines to standardise the translation of the CORE-OM into different languages. However this thesis argues that these guidelines are incomplete. Instead International Test Commission (ITC) guidelines are recommended as a culturally sensitive method to supplement current CORE-OM translation guidelines, in order to generate a valid Xhosa measure of distress. A mixed methods approach is applied which first investigates the construct equivalence and bias of the CORE-OM English version within a South African student population sample, both qualitatively and quantitatively, in order to establish the degree of adaptation required to generate a valid Xhosa version of distress. Next the CORE-OM English version is translated into Xhosa using the five-stage translation design prescribed by the CORE System Trust, supplemented by ITC guidelines. All changes made to the CORE-OM during translation into Xhosa are documented. The CORE-OM Xhosa version is then investigated for reliability and validity. This investigation reveals low internal reliability within the subjective wellbeing domain indicating that these items are less meaningful as depictions of distress within the Xhosa language. A reduced version of the CORE-OM demonstrates strong psychometric properties as a valid Xhosa measure of distress.
- Full Text:
- Date Issued: 2013
- Authors: Campbell, Megan Michelle
- Date: 2013 , 2013-06-06
- Subjects: Psychometrics -- Research -- South Africa Psychology -- Mathematical models -- Research -- South Africa Psychological tests -- Research -- South Africa Mental health services -- Research -- South Africa Health services accessibility -- Research -- South Africa Language disorders -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2894 , http://hdl.handle.net/10962/d1001538
- Description: In South Africa access to mental healthcare resources is restricted for a number of reasons including language barriers that prevent suitable communication between mental healthcare professionals and African language speaking South Africans. The translation of psychometric tools into African languages has been identified as one method in improving access to psychological services for African language speakers. The Clinical Outcomes in Routine Evaluation - Outcome Measure (CORE-OM) has demonstrated its clinical utility within the United Kingdom (UK) National Healthcare Service (NHS) as a standardised psychotherapy outcome measure that evaluates the degree of psychological distress individuals present with at the start of psychotherapy treatment, and the degree of change that has been effected at the termination of therapy. A measure like the CORE-OM holds valuable clinical utility for the South African context. This thesis argues that the availability of a valid Xhosa version of the CORE-OM would allow for improved access to psychotherapy resources for Xhosa speaking individuals, and allow for the evaluation of the effectiveness of psychotherapy interventions conducted in Xhosa. The CORE-OM developers have provided a translation design and set of guidelines to standardise the translation of the CORE-OM into different languages. However this thesis argues that these guidelines are incomplete. Instead International Test Commission (ITC) guidelines are recommended as a culturally sensitive method to supplement current CORE-OM translation guidelines, in order to generate a valid Xhosa measure of distress. A mixed methods approach is applied which first investigates the construct equivalence and bias of the CORE-OM English version within a South African student population sample, both qualitatively and quantitatively, in order to establish the degree of adaptation required to generate a valid Xhosa version of distress. Next the CORE-OM English version is translated into Xhosa using the five-stage translation design prescribed by the CORE System Trust, supplemented by ITC guidelines. All changes made to the CORE-OM during translation into Xhosa are documented. The CORE-OM Xhosa version is then investigated for reliability and validity. This investigation reveals low internal reliability within the subjective wellbeing domain indicating that these items are less meaningful as depictions of distress within the Xhosa language. A reduced version of the CORE-OM demonstrates strong psychometric properties as a valid Xhosa measure of distress.
- Full Text:
- Date Issued: 2013
Exploring and expanding capabilities, sustainability and gender justice in science teacher education : case studies in Zimbabwe and South Africa
- Authors: Chikunda, Charles
- Date: 2013 , 2013-08-30
- Subjects: Science teachers -- Training of -- South Africa -- Case studies Science teachers -- Training of -- Zimbabwe -- Case studies Mathematics teachers -- Training of -- South Africa -- Case studies Women in education -- South Africa -- Case studies Women in education -- Zimbabwe -- Case studies Environmental education -- Study and teaching -- Case studies Curriculum planning -- South Africa Curriculum planning -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1887 , http://hdl.handle.net/10962/d1006026
- Description: The focus of this study was to explore and expand capabilities, sustainability and gender justice in Science, Mathematics and Technical subjects (SMTs) in teacher education curriculum practices as a process of Education for Sustainable Development in two case studies in Zimbabwe and South Africa. The study begins by discussing gender and science education discourse, locating it within Education for Sustainable Development discourse. Through this nexus, the study was able to explore gender and sustainability responsiveness of the curriculum practices of teacher educators in Science, Mathematics and Technical subjects; scrutinise underlying mechanisms that affect (promote or constrain) gender and sustainability responsive curriculum practices; and understand if and how teacher education curriculum practices consider the functionings and capabilities of females in relation to increased socio-ecological risk in a Southern African context. Influenced by a curriculum transformation commitment, an expansive learning phase was conducted to promote gender and sustainability responsive pedagogies in teacher education curriculum practices. As shown in the study, the expansive learning processes resulted in (re)conceptualising the curriculum practices (object), analysis of contradictions and developing new ways of doing work. Drawing from the sensitising concepts of dialectics, reflexivity and agency, the study worked with the three theoretical approaches of Cultural Historical Activity Theory (CHAT), feminist theory and capabilities theory. The capability and feminist lenses were used in the exploration of gender and sustainability responsiveness in science teacher education curriculum practices. CHAT, through its associated methodology of Developmental Work Research, offered the opportunity for researcher and participants in this study to come together to question and analyse curriculum practices and model new ways of doing work. Case study research was used in two case studies of teacher education curriculum practices in Science, Mathematics and Technical subjects, one in Zimbabwe and one in South Africa. Each case study is constituted with a networked activity system. The study used in-depth and focus group interviews and document analysis to explore gender and sustainability responsiveness in curriculum practices and to generate mirror data. Inductive and abductive modes of inference, and Critical Discourse Analysis were used to analyse data. This data was then used in Change Laboratory Workshops, where double stimulation and focus group discussions contributed to the expansive learning process. Findings from the exploration phase of the study revealed that most teacher educators in the two case studies had some basic levels of gender sensitivity, meaning that they had ability to perceive existing gender inequalities as it applies only to gender disaggregated data especially when it comes to enrolment and retention. However, there was no institutionalised pedagogic device in place in both case studies aimed at equipping future teachers with knowledge, skills, attitudes and values to promote aspects of capabilities (well-being achievement, wellbeing freedom, agency achievement and agency freedom) for girls in Science, Mathematics and Technical subjects. Science, Mathematics and Technical subjects teacher educators' curriculum practices were gender neutral, but in a gendered environment. This was a pedagogical tension that was visible in both case studies. On the other hand, socio-ecological issues, in cases where they were incorporated into the curriculum, were incorporated in a gender blind or gender neutral manner. Social ecological concerns such as climate change were treated as if they were not gendered both in their impact and in their mitigation and adaptation. It emerged that causal mechanisms shaping this situation were of a socio-political nature: there exist cultural differences between students and teacher educators; patriarchal ideology and hegemony; as well as other interfering binaries such as race and class. Other curriculum related constraints, though embedded in the socio-cultural-political nexus, include: rigid and content heavy curriculum, coupled with students who come into the system with inadequate content knowledge; and philosophy informing pedagogy namely scientism, with associated instrumentalist and functionalist tenets. All these led to contradictions between pedagogical practices with those expected by the Education for Sustainable Development framework. The study contributes in-depth insight into science teacher education curriculum development. By locating the study at the nexus of gender and Science, Mathematics and Technical subjects within the Education for Sustainable Development discourse, using the ontological lenses of feminist and capabilities, it was possible to interrogate aspects of quality and relevance of the science teacher education curriculum. The study also provides insight into participatory research and learning processes especially within the context of policy and curriculum development. It provides empirical evidence of mobilising reflexivity amongst both policy makers and policy implementers towards building human agency in policy translation for a curriculum transformation that is critical for responding to contemporary socio-ecological risks. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
- Authors: Chikunda, Charles
- Date: 2013 , 2013-08-30
- Subjects: Science teachers -- Training of -- South Africa -- Case studies Science teachers -- Training of -- Zimbabwe -- Case studies Mathematics teachers -- Training of -- South Africa -- Case studies Women in education -- South Africa -- Case studies Women in education -- Zimbabwe -- Case studies Environmental education -- Study and teaching -- Case studies Curriculum planning -- South Africa Curriculum planning -- Zimbabwe
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1887 , http://hdl.handle.net/10962/d1006026
- Description: The focus of this study was to explore and expand capabilities, sustainability and gender justice in Science, Mathematics and Technical subjects (SMTs) in teacher education curriculum practices as a process of Education for Sustainable Development in two case studies in Zimbabwe and South Africa. The study begins by discussing gender and science education discourse, locating it within Education for Sustainable Development discourse. Through this nexus, the study was able to explore gender and sustainability responsiveness of the curriculum practices of teacher educators in Science, Mathematics and Technical subjects; scrutinise underlying mechanisms that affect (promote or constrain) gender and sustainability responsive curriculum practices; and understand if and how teacher education curriculum practices consider the functionings and capabilities of females in relation to increased socio-ecological risk in a Southern African context. Influenced by a curriculum transformation commitment, an expansive learning phase was conducted to promote gender and sustainability responsive pedagogies in teacher education curriculum practices. As shown in the study, the expansive learning processes resulted in (re)conceptualising the curriculum practices (object), analysis of contradictions and developing new ways of doing work. Drawing from the sensitising concepts of dialectics, reflexivity and agency, the study worked with the three theoretical approaches of Cultural Historical Activity Theory (CHAT), feminist theory and capabilities theory. The capability and feminist lenses were used in the exploration of gender and sustainability responsiveness in science teacher education curriculum practices. CHAT, through its associated methodology of Developmental Work Research, offered the opportunity for researcher and participants in this study to come together to question and analyse curriculum practices and model new ways of doing work. Case study research was used in two case studies of teacher education curriculum practices in Science, Mathematics and Technical subjects, one in Zimbabwe and one in South Africa. Each case study is constituted with a networked activity system. The study used in-depth and focus group interviews and document analysis to explore gender and sustainability responsiveness in curriculum practices and to generate mirror data. Inductive and abductive modes of inference, and Critical Discourse Analysis were used to analyse data. This data was then used in Change Laboratory Workshops, where double stimulation and focus group discussions contributed to the expansive learning process. Findings from the exploration phase of the study revealed that most teacher educators in the two case studies had some basic levels of gender sensitivity, meaning that they had ability to perceive existing gender inequalities as it applies only to gender disaggregated data especially when it comes to enrolment and retention. However, there was no institutionalised pedagogic device in place in both case studies aimed at equipping future teachers with knowledge, skills, attitudes and values to promote aspects of capabilities (well-being achievement, wellbeing freedom, agency achievement and agency freedom) for girls in Science, Mathematics and Technical subjects. Science, Mathematics and Technical subjects teacher educators' curriculum practices were gender neutral, but in a gendered environment. This was a pedagogical tension that was visible in both case studies. On the other hand, socio-ecological issues, in cases where they were incorporated into the curriculum, were incorporated in a gender blind or gender neutral manner. Social ecological concerns such as climate change were treated as if they were not gendered both in their impact and in their mitigation and adaptation. It emerged that causal mechanisms shaping this situation were of a socio-political nature: there exist cultural differences between students and teacher educators; patriarchal ideology and hegemony; as well as other interfering binaries such as race and class. Other curriculum related constraints, though embedded in the socio-cultural-political nexus, include: rigid and content heavy curriculum, coupled with students who come into the system with inadequate content knowledge; and philosophy informing pedagogy namely scientism, with associated instrumentalist and functionalist tenets. All these led to contradictions between pedagogical practices with those expected by the Education for Sustainable Development framework. The study contributes in-depth insight into science teacher education curriculum development. By locating the study at the nexus of gender and Science, Mathematics and Technical subjects within the Education for Sustainable Development discourse, using the ontological lenses of feminist and capabilities, it was possible to interrogate aspects of quality and relevance of the science teacher education curriculum. The study also provides insight into participatory research and learning processes especially within the context of policy and curriculum development. It provides empirical evidence of mobilising reflexivity amongst both policy makers and policy implementers towards building human agency in policy translation for a curriculum transformation that is critical for responding to contemporary socio-ecological risks. , Microsoft� Word 2010 , Adobe Acrobat 9.54 Paper Capture Plug-in
- Full Text:
- Date Issued: 2013
Estuarine-dependency and multiple habitat use by dusky kob Argyrosomus Japonicus (Pisces: Sciaenidae)
- Authors: Childs, Amber-Robyn
- Date: 2013
- Subjects: Argyrosomus -- Habitat -- South Africa -- Algoa Bay , Argyrosomus -- Behavior -- South Africa -- Algoa Bay , Argyrosomus -- Migration -- South Africa -- Algoa Bay , Estuarine fishes -- South Africa -- Algoa Bay , Habitat selection -- South Africa -- Algoa Bay , Argyrosomus -- South Africa -- Sundays Estuary (Eastern Cape) , Underwater acoustic telemetry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5386 , http://hdl.handle.net/10962/d1020241
- Description: Dusky kob Argyrosomus japonicus is a wide-ranging estuarine-dependent Sciaenid and an important fishery species throughout most of its distribution. It is one of South Africa’s most valuable coastal fishery species. High levels of juvenile exploitation in estuaries and ineffective management regulations have led to stock collapse, highlighting the need to better understand the spatial and temporal aspects of estuarine-dependency and multiple habitat use. Habitat connectivity is a critical property of estuarine-associated fishes and it therefore follows that knowledge of this link is fundamental in understanding population dynamics and the nursery role of estuarine and/or marine habitats. While dusky kob occur in both estuaries and nearshore coastal zones, limited information on connectivity among these habitats exists. The aim of this study is to assess the role of estuarine nursery habitats in the life cycle of the dusky kob by examining multiple habitat connectivity and determining the drivers associated with estuarine use. A total of 96 dusky kob (237–1280 mm total length) were tagged with acoustic transmitters in both the estuarine and marine environments of Algoa Bay, Eastern Cape, South Africa between May 2008 and September 2010. Their movements were monitored using a network of automated data-logging acoustic receivers deployed in the Sundays Estuary, seven neighbouring estuarine habitats, two commercial harbours and various sites within Algoa Bay. And more...
- Full Text:
- Date Issued: 2013
- Authors: Childs, Amber-Robyn
- Date: 2013
- Subjects: Argyrosomus -- Habitat -- South Africa -- Algoa Bay , Argyrosomus -- Behavior -- South Africa -- Algoa Bay , Argyrosomus -- Migration -- South Africa -- Algoa Bay , Estuarine fishes -- South Africa -- Algoa Bay , Habitat selection -- South Africa -- Algoa Bay , Argyrosomus -- South Africa -- Sundays Estuary (Eastern Cape) , Underwater acoustic telemetry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5386 , http://hdl.handle.net/10962/d1020241
- Description: Dusky kob Argyrosomus japonicus is a wide-ranging estuarine-dependent Sciaenid and an important fishery species throughout most of its distribution. It is one of South Africa’s most valuable coastal fishery species. High levels of juvenile exploitation in estuaries and ineffective management regulations have led to stock collapse, highlighting the need to better understand the spatial and temporal aspects of estuarine-dependency and multiple habitat use. Habitat connectivity is a critical property of estuarine-associated fishes and it therefore follows that knowledge of this link is fundamental in understanding population dynamics and the nursery role of estuarine and/or marine habitats. While dusky kob occur in both estuaries and nearshore coastal zones, limited information on connectivity among these habitats exists. The aim of this study is to assess the role of estuarine nursery habitats in the life cycle of the dusky kob by examining multiple habitat connectivity and determining the drivers associated with estuarine use. A total of 96 dusky kob (237–1280 mm total length) were tagged with acoustic transmitters in both the estuarine and marine environments of Algoa Bay, Eastern Cape, South Africa between May 2008 and September 2010. Their movements were monitored using a network of automated data-logging acoustic receivers deployed in the Sundays Estuary, seven neighbouring estuarine habitats, two commercial harbours and various sites within Algoa Bay. And more...
- Full Text:
- Date Issued: 2013
Characterisation of surfaces modified through self-assembled monolayers and click chemistry
- Authors: Coates, Megan Patricia
- Date: 2013
- Subjects: Monomolecular films Gold Adsorption Nanotubes Self-assembly (Chemistry) Self-assembly (Chemistry) Scanning electrochemical microscopy X-ray photoelectron spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4277 , http://hdl.handle.net/10962/d1001684
- Description: Different approaches to surface modification were investigated in this work on gold, glassy carbon, multi-walled carbon nanotube paper and on single-walled carbon nanotubes adsorbed on glassy carbon. These approaches include electrochemical grafting, electropolymerisation, click chemistry, axial ligation, adsorption and self-assembled monolayers. The modified surfaces were characterised using a variety of techniques; predominantly electrochemistry, scanning electrochemical microscopy and X-ray photoelectron spectroscopy. For the formation of self-assembled monolayers on gold, four new manganese(III) phthalocyanines (1a-d), octa-substituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups were synthesized and characterised. X-ray photoelectron spectroscopy was used to show the formation of a sulphur-gold bond. A number of approaches using 4-azidoaniline (2a) combined with azide-alkyne click chemistry and electrochemistry were also used to anchor ferrocene and pyridine moieties on to the carbon surfaces, including direct in situ diazotation and grafting, electropolymerisation, and the synthesis of the diazonium salt followed by grafting. Iron phthalocyanine was linked to the pyridine-clicked surfaces through axial ligation, where the strong axial bond formed by the interaction between the central metal and the lone pair of the nitrogen in the pyridine group resulted in stable modified electrodes. The potential of these surfaces for the detection of analytes such as thiocyanate, hydrazine and sulphite are briefly shown as well. This work also describes for the first time the possibility of performing local micro-electrochemical grafting of a gold substrate by 4-azidobenzenediazonium (2b) using scanning electrochemical microscopy in a single and simple one step approach, without complications from adsorption.
- Full Text:
- Date Issued: 2013
- Authors: Coates, Megan Patricia
- Date: 2013
- Subjects: Monomolecular films Gold Adsorption Nanotubes Self-assembly (Chemistry) Self-assembly (Chemistry) Scanning electrochemical microscopy X-ray photoelectron spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4277 , http://hdl.handle.net/10962/d1001684
- Description: Different approaches to surface modification were investigated in this work on gold, glassy carbon, multi-walled carbon nanotube paper and on single-walled carbon nanotubes adsorbed on glassy carbon. These approaches include electrochemical grafting, electropolymerisation, click chemistry, axial ligation, adsorption and self-assembled monolayers. The modified surfaces were characterised using a variety of techniques; predominantly electrochemistry, scanning electrochemical microscopy and X-ray photoelectron spectroscopy. For the formation of self-assembled monolayers on gold, four new manganese(III) phthalocyanines (1a-d), octa-substituted at the peripheral position with pentylthio, decylthio, benzylthio, and phenylthio groups were synthesized and characterised. X-ray photoelectron spectroscopy was used to show the formation of a sulphur-gold bond. A number of approaches using 4-azidoaniline (2a) combined with azide-alkyne click chemistry and electrochemistry were also used to anchor ferrocene and pyridine moieties on to the carbon surfaces, including direct in situ diazotation and grafting, electropolymerisation, and the synthesis of the diazonium salt followed by grafting. Iron phthalocyanine was linked to the pyridine-clicked surfaces through axial ligation, where the strong axial bond formed by the interaction between the central metal and the lone pair of the nitrogen in the pyridine group resulted in stable modified electrodes. The potential of these surfaces for the detection of analytes such as thiocyanate, hydrazine and sulphite are briefly shown as well. This work also describes for the first time the possibility of performing local micro-electrochemical grafting of a gold substrate by 4-azidobenzenediazonium (2b) using scanning electrochemical microscopy in a single and simple one step approach, without complications from adsorption.
- Full Text:
- Date Issued: 2013
Modulation of Plasmodium falciparum chaperones PfHsp70-1 and PfHsp70-x by small molecules
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
- Date Issued: 2013
- Authors: Cockburn, Ingrid Louise
- Date: 2013
- Subjects: Plasmodium falciparum Heat shock proteins Molecular chaperones Homeostasis Protein folding Malaria Antimalarials Escherichia coli
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3887 , http://hdl.handle.net/10962/d1001747
- Description: The heat shock proteins of ~ 70 kDa (Hsp70s) are a conserved group of molecular chaperones important in maintaining the protein homeostasis in cells, carrying out functions including refolding of misfolded or unfolded proteins. Hsp70s function in conjunction with a number of other proteins including Hsp40 cochaperones. Central to the regulation Hsp70 activity is the Hsp70 ATPase cycle, involving ATP hydrolysis by Hsp70, and stimulation of this ATP hydrolysis by Hsp40. PfHsp70-1, the major cytosolic Hsp70 in the malaria parasite, Plasmodium falciparum, and PfHsp70-x, a novel malarial Hsp70 recently found to be exported to the host cell cytosol during the erythrocytic stages of the P. falciparum lifecycle, are both thought to play important roles in the malaria parasite’s survival and virulence, and thus represent novel antimalarial targets. Modulation of the function of these proteins by small molecules could thus lead to the development of antimalarials with novel targets and mechanisms. In the present study, malarial Hsp70s (PfHsp70-1 and PfHsp70-x), human Hsp70 (HSPA1A), malarial Hsp40 (PfHsp40) and human Hsp40 (Hsj1a) were recombinantly produced in Escherichia coli. In a characterisation of the chaperone activity of recombinant PfHsp70-x, the protein was found to have a basal ATPase activity (15.7 nmol ATP/min/mg protein) comparable to that previously described for PfHsp70-1, and an aggregation suppression activity significantly higher than that of PfHsp70-1. In vitro assays were used to screen five compounds of interest (lapachol, bromo-β-lapachona and malonganenones A, B and C) belonging to two compound classes (1,4 naphthoquinones and prenylated alkaloids) for modulatory effects on PfHsp70-1, PfHsp70-x and HsHsp70. A wide range of effects by compounds on the chaperone activities of Hsp70s was observed, including differential effects by compounds on different Hsp70s despite high conservation (≥ 70 % sequence identity) between the Hsp70s. The five compounds were shown to interact with all three Hsp70s in in vitro binding studies. Differential modulation by compounds was observed between the Hsj1a-stimulated ATPase activities of different Hsp70s, suggestive of not only a high degree of specificity of compounds to chaperone systems, but also distinct interactions between different Hsp70s and Hjs1a. The effects of compounds on the survival of P. falciparum parasites as well as mammalian cells was assessed. Bromo-β-lapachona was found to have broad effects across all systems, modulating the chaperone activities of all three Hsp70s, and showing significant toxicity toward both P. falciparum parasites and mammalian cells in culture. Malonganenone A was found to modulate only the malarial Hsp70s, not human Hsp70, showing significant toxicity toward malarial parasites (IC₅₀ ~ 0.8 μM), and comparatively low toxicity toward mammalian cells, representing therefore a novel starting point for a new class of antimalarials potentially targeting a new antimalarial drug target, Hsp70.
- Full Text:
- Date Issued: 2013
Standards to facilitate optimal experiences of short-term study abroad nursing students at a higher education institution
- Authors: Du Rand, Sussara Maria
- Date: 2013
- Subjects: Nursing -- Study and teaching -- United States , Transcultural nursing , Nursing -- Cross-cultural studies , Foreign study , Nursing students
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10066 , http://hdl.handle.net/10948/d1020659
- Description: Advances in technology have made globalization and internationalization a reality in the world. National borders are becoming more permeable and migration of goods, services, and health care workers takes place more readily. Higher Education Institutions (HEIs) have become competitors and vendors in the global knowledge economy and are expected to develop job seekers that are responsible and engaged global citizens and employees. Offering study abroad programmes is one of the ways that HEIs achieve this goal. It is estimated that in 2010, 4.7 million people studied abroad (OECD, 2012:360), and it is anticipated that this number will grow to 15 million by the year 2025 (Altbach & Knight, 2006:9). South Africa is emerging as a regional hub for study and research in sub-Saharan Africa (UNESCO: 2012b). Many organizations that train nurses are internationalizing their curriculum which effectively means that Schools of Nursing are seeking placement for students to study, gain insight into other cultures and practices, and to gain clinical experience in other countries. Students, the customers of the Higher Education Institutions, often pay large sums of money to undertake these study abroad programmes and therefore expect good quality learning experiences in return. The aim of this qualitative, contextual, exploratory, and descriptive study was to explore and describe the expectations and experiences of international nursing students and faculty members at a Higher Educational Institution in South Africa in order to develop standards that will enable HEIs to optimize the experiences of short-term study abroad nursing students. An in-depth contextual investigation was conducted on globalization and internationalization, as well as the higher education and health systems of three countries to understand the context of the study abroad programmes. Qualitative data was gathered from students and faculty members using focus groups and individual interviews to establish their expectations and experiences of the programme. Thematic synthesis was carried out on the contextual data and the qualitative data. Thereafter, thematic synthesis analysis was conducted using both sets of results to develop standards that can be used to optimize the experience of short-term study abroad nursing students at a HEI. A total of 35 standards were developed around the following main themes: the objectives of study abroad programmes should be stated clearly before arrival and include the expectations of the global, national, and local communities, the higher education institution and the staff and students; study abroad programmes should be managed in an ethical manner and in an enabling environment, as part of their strategic goals and plans of a HEI; students should be exposed to a variety of experiences and differences between the sending and hosting countries during their study abroad programmes; Standards to Facilitate Optimal Experiences of Short-term Study Abroad Nursing Students at a HEI; study abroad programmes should be evaluated at different intervals and levels to ensure quality of the programmes and to ensure that the objectives/outcomes are met. A limitation of the study was the sampling of the clinical mentors which did not include representatives from the overseas universities. It is recommended that the standards that were developed in this study be introduced and tested in HEIs and that more research be conducted on different levels and groups with regard to study abroad programmes in future.
- Full Text:
- Date Issued: 2013
- Authors: Du Rand, Sussara Maria
- Date: 2013
- Subjects: Nursing -- Study and teaching -- United States , Transcultural nursing , Nursing -- Cross-cultural studies , Foreign study , Nursing students
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10066 , http://hdl.handle.net/10948/d1020659
- Description: Advances in technology have made globalization and internationalization a reality in the world. National borders are becoming more permeable and migration of goods, services, and health care workers takes place more readily. Higher Education Institutions (HEIs) have become competitors and vendors in the global knowledge economy and are expected to develop job seekers that are responsible and engaged global citizens and employees. Offering study abroad programmes is one of the ways that HEIs achieve this goal. It is estimated that in 2010, 4.7 million people studied abroad (OECD, 2012:360), and it is anticipated that this number will grow to 15 million by the year 2025 (Altbach & Knight, 2006:9). South Africa is emerging as a regional hub for study and research in sub-Saharan Africa (UNESCO: 2012b). Many organizations that train nurses are internationalizing their curriculum which effectively means that Schools of Nursing are seeking placement for students to study, gain insight into other cultures and practices, and to gain clinical experience in other countries. Students, the customers of the Higher Education Institutions, often pay large sums of money to undertake these study abroad programmes and therefore expect good quality learning experiences in return. The aim of this qualitative, contextual, exploratory, and descriptive study was to explore and describe the expectations and experiences of international nursing students and faculty members at a Higher Educational Institution in South Africa in order to develop standards that will enable HEIs to optimize the experiences of short-term study abroad nursing students. An in-depth contextual investigation was conducted on globalization and internationalization, as well as the higher education and health systems of three countries to understand the context of the study abroad programmes. Qualitative data was gathered from students and faculty members using focus groups and individual interviews to establish their expectations and experiences of the programme. Thematic synthesis was carried out on the contextual data and the qualitative data. Thereafter, thematic synthesis analysis was conducted using both sets of results to develop standards that can be used to optimize the experience of short-term study abroad nursing students at a HEI. A total of 35 standards were developed around the following main themes: the objectives of study abroad programmes should be stated clearly before arrival and include the expectations of the global, national, and local communities, the higher education institution and the staff and students; study abroad programmes should be managed in an ethical manner and in an enabling environment, as part of their strategic goals and plans of a HEI; students should be exposed to a variety of experiences and differences between the sending and hosting countries during their study abroad programmes; Standards to Facilitate Optimal Experiences of Short-term Study Abroad Nursing Students at a HEI; study abroad programmes should be evaluated at different intervals and levels to ensure quality of the programmes and to ensure that the objectives/outcomes are met. A limitation of the study was the sampling of the clinical mentors which did not include representatives from the overseas universities. It is recommended that the standards that were developed in this study be introduced and tested in HEIs and that more research be conducted on different levels and groups with regard to study abroad programmes in future.
- Full Text:
- Date Issued: 2013
Single-end reflectometric measurements of polarization-mode dispersion in single-mode optical fibres
- Authors: Fosuhene, Samuel Kofi
- Date: 2013
- Subjects: Fiber optics , Polarization (Light) , Optical measurements
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6280 , vital:21069
- Description: In this thesis two novel single-end methods are applied to measure and characterize polarization mode dispersion in single mode optical fibres. Polarization mode dispersion (PMD) is an important factor negatively affecting the successful implementation of high speed long haul optical fibre networks operating at bit rates of 10Gb/s and above. PMD measurements are thus important for quality control during manufacturing and cabling processes. It is also useful for network operators planning to upgrade bitrates in existing networks to 10Gb/s and beyond. In an optical fibre link, sections with particularly high PMD may act to increase the entire PMD of the link. Identifying and replacing such sections can greatly reduce the PMD of the link. PMD measurements can be forward or single-end. In forward measurements, both ends of the fibre are used for input and detection. In single-end configuration, only one end of the fibre is used. For this reason, single-end measurements are more practical for the field where fibre ends are situated several kilometres apart. Single-end techniques can be implemented with a continuous wave for non-local PMD measurements (by Fresnel reflection). If a pulsed wave is used, local measurements can be achieved (by total power due to Rayleigh scattering). Two single-end schemes, one based on Fresnel reflection and the other due to Rayleigh scattering have been applied to measure non-local and local PMD of standard single mode optical fibres. For the non-local PMD measurements, the general interferometric technique (GINTY) was modified to operate in a round-trip configuration. In this configuration, the fibre was treated as a concatenation of two identical fibre segments. Three different sets of fibres were investigated, each set representing a particular mode coupling regime. For polarization maintaining fibres, (PMFs), with no mode coupling, a factor of two was found between forward and single-end measurements. For long single mode fibres in the long length regime, the factor was 1.4. For a combination of PMF and single mode fibres, a factor of 1.6 was obtained. The method which is accurate, repeatable, low cost and robust is very suitable for field applications. The second method is the polarization optical time domain reflectometric (P-OTDR) technique. This technique performs local birefringence measurements by measuring the evolution of the states of polarization (SOP). The birefringence information from such measurements was extracted and analysed to characterise four different fibres. Beat lengths and correlation lengths extracted from the P-OTDR were used to calculate the differential group delay (DGD) of the fibres. Next an expression for the root-mean-square differential group delay was derived and applied to the birefringence measurements to calculate the DGDs at a single wavelength. This method which operates at a single wavelength has a huge advantage. Firstly it is able to measure completely all the fibre characteristic parameters. Secondly it can measure mean DGD, root mean square DGD and instantaneous DGD. A plot of instantaneous DGD vs. length enables one to identify and eliminate sections with particularly high DGD. Finally since the P-OTDR system operates with a single wavelength, real time monitoring of PMD is possible via multiplexing. The results obtained are repeatable, accurate and are in good agreement with the standard Jones Matrix Eigenanalysis (JME) technique.
- Full Text:
- Date Issued: 2013
Single-end reflectometric measurements of polarization-mode dispersion in single-mode optical fibres
- Authors: Fosuhene, Samuel Kofi
- Date: 2013
- Subjects: Fiber optics , Polarization (Light) , Optical measurements
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6280 , vital:21069
- Description: In this thesis two novel single-end methods are applied to measure and characterize polarization mode dispersion in single mode optical fibres. Polarization mode dispersion (PMD) is an important factor negatively affecting the successful implementation of high speed long haul optical fibre networks operating at bit rates of 10Gb/s and above. PMD measurements are thus important for quality control during manufacturing and cabling processes. It is also useful for network operators planning to upgrade bitrates in existing networks to 10Gb/s and beyond. In an optical fibre link, sections with particularly high PMD may act to increase the entire PMD of the link. Identifying and replacing such sections can greatly reduce the PMD of the link. PMD measurements can be forward or single-end. In forward measurements, both ends of the fibre are used for input and detection. In single-end configuration, only one end of the fibre is used. For this reason, single-end measurements are more practical for the field where fibre ends are situated several kilometres apart. Single-end techniques can be implemented with a continuous wave for non-local PMD measurements (by Fresnel reflection). If a pulsed wave is used, local measurements can be achieved (by total power due to Rayleigh scattering). Two single-end schemes, one based on Fresnel reflection and the other due to Rayleigh scattering have been applied to measure non-local and local PMD of standard single mode optical fibres. For the non-local PMD measurements, the general interferometric technique (GINTY) was modified to operate in a round-trip configuration. In this configuration, the fibre was treated as a concatenation of two identical fibre segments. Three different sets of fibres were investigated, each set representing a particular mode coupling regime. For polarization maintaining fibres, (PMFs), with no mode coupling, a factor of two was found between forward and single-end measurements. For long single mode fibres in the long length regime, the factor was 1.4. For a combination of PMF and single mode fibres, a factor of 1.6 was obtained. The method which is accurate, repeatable, low cost and robust is very suitable for field applications. The second method is the polarization optical time domain reflectometric (P-OTDR) technique. This technique performs local birefringence measurements by measuring the evolution of the states of polarization (SOP). The birefringence information from such measurements was extracted and analysed to characterise four different fibres. Beat lengths and correlation lengths extracted from the P-OTDR were used to calculate the differential group delay (DGD) of the fibres. Next an expression for the root-mean-square differential group delay was derived and applied to the birefringence measurements to calculate the DGDs at a single wavelength. This method which operates at a single wavelength has a huge advantage. Firstly it is able to measure completely all the fibre characteristic parameters. Secondly it can measure mean DGD, root mean square DGD and instantaneous DGD. A plot of instantaneous DGD vs. length enables one to identify and eliminate sections with particularly high DGD. Finally since the P-OTDR system operates with a single wavelength, real time monitoring of PMD is possible via multiplexing. The results obtained are repeatable, accurate and are in good agreement with the standard Jones Matrix Eigenanalysis (JME) technique.
- Full Text:
- Date Issued: 2013
The restoration of an alien-invaded riparian zone in grassy fynbos, South Africa
- Authors: Fourie, Saskia
- Date: 2013
- Subjects: Fynbos ecology -- South Africa Riparian ecology -- South Africa Riparian restoration -- South Africa Alien plants -- South Africa Invasive plants -- South Africa Endemic plants -- South Africa Plants -- Effect of fires on -- South Africa Soil seed banks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4733 , http://hdl.handle.net/10962/d1003840
- Description: The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
- Full Text:
- Date Issued: 2013
- Authors: Fourie, Saskia
- Date: 2013
- Subjects: Fynbos ecology -- South Africa Riparian ecology -- South Africa Riparian restoration -- South Africa Alien plants -- South Africa Invasive plants -- South Africa Endemic plants -- South Africa Plants -- Effect of fires on -- South Africa Soil seed banks -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4733 , http://hdl.handle.net/10962/d1003840
- Description: The most recent surveys in South Africa estimate that invasions are still increasing, despite substantial clearing efforts. Riparian systems in South Africa are particularly vulnerable to invasion by woody IAPs. This thesis addresses the restoration of alien‐invaded riparian systems, by investigating the factors that facilitate or constrain spontaneous recovery and influence the trajectories of succession. These factors include invasion history and management history, especially the use of fire. A seedling emergence approach was used to test the presence of a viable pre‐fire seedbank, and the effect of fire on the seed bank. The efficacy of some active restoration interventions was also tested, with the aim to return invasion‐resistant, indigenous vegetation with a structure and function representative of uninvaded sites. The findings of this study indicated the presence of a viable and persistent riparian soil seed bank, even after 30 years of intermtittent invasion as well as two fire cycles under invasion. It shows that the management practice of fell‐and‐burn resulted in high soil temperatures, and that this reduced the indigenous soil seed bank density, especially in the upper soil layer. Clear germination sequences and patterns of emergence over time for different species were observed during this study, with many species exhibiting delayed emergence relative to the timing of the fire event. It is proposed that manipulation of the season of fire could be used to selectively optimise the order of arrival and therefore superior recruitment of some species over others in the Eastern Cape fynbos, and thus alter the trajectories of recovery of vegetation towards a more desired state. Active restoration in the form of indigenous seed and plant additions resulted in a significantly higher indigenous cover after seven months, compared to a control (passive restoration) or restoring with grass. Indigenous cover and composition was also strongly influenced by lateral zonation, and some key guilds and species were missing or present in much lower densities compared to reference sites. Grass restoration significantly suppressed the regeneration of A. longifolia, as well as the regeneration of indigenous species. Biotic resistance can thus be achieved through restoration, and it could be a powerful tool in the management of IAPs, although the deliberate introduction of grass after clearing in fynbos also reduces biodiversity and could have unforeseen consequences to riparian function.
- Full Text:
- Date Issued: 2013
Molecular signaling in colorectal carcinogenesis : the roles and relationships of beta-catenin, PPARgamma and COX-2
- Authors: Fredericks, Ernst
- Date: 2013
- Subjects: Colon (Anatomy) -- Cancer , Cyclooxygenase 2 , Peroxisomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10357 , http://hdl.handle.net/10948/d1021014
- Description: Colorectal cancer (CRC) is a common disease with significant morbidity and mortality. In spite of significant advances in understanding the molecular signaling in this disorder, unanswered questions remain. Cyclooxygenase-2 (COX-2) and β-catenin have established roles in colorectal carcinogenesis, with both being upregulated early in the disease course. The role of peroxisome proliferator-activated receptor γ (PPARγ) is less clear, but has been shown to be downregulated in colon cancer models. Butyrate, a short chain fatty acid, produced by colon microbiota and transported into the colonocyte by transporter proteins, appears to be important in early carcinogenesis. The butyrate concentration is reduced in CRC and so are its transporters. Interleukin-17 (IL-17) plays a role in colitis-associated colorectal cancer (CAC), but its function in sporadic CRC is less clear. Similarly, Protein kinase C (PKC) has proven involvement in many solid tumours, including CRC, but its exact mechanistic role is still speculative. AIM: To investigate the role and possible signaling pathways of the major role players, β-catenin, COX-2 and PPARγ in early CRC. Further, to elucidate the mechanistic pathways of butyrate and its transporters, IL-17 and PKC in CRC. METHOD: Informed consent was obtained for all patients. Patients were recruited in various disease categories, including normal, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and CRC. Colon biopsy specimens were obtained during colonoscopy and used for immunohistochemistry (IHC) and gene expression analysis of the above genes by quantitative polymerase chain reaction (qPCR). RESULTS: β-catenin mRNA and protein expression was increased in CRC and the IBD groups compared to the normal group, while it was reduced in the IBS groups. COX-2 mRNA expression showed a steady increase from normal, through IBS, IBD and CRC groups to a statistically significant degree. The COX-2 protein expression, however, did not match the mRNA expression with increased COX-2 protein expression in normal and IBS groups and reduced expression in IBD and CRC groups. PPARγ mRNA expression was unchanged in IBD and CRC groups, but significantly increased in the IBS group compared to normal. Butyrate transporter, SLC16A1 mRNA was significantly reduced in CRC, but also in the IBS groups, which was unexpected. In the IBD group, SLC16A1 mRNA was unchanged in Crohn’s disease (CD) but significantly reduced in ulcerative colitis (UC). Similarly, SLC5A8 mRNA expression was significantly reduced in the CRC as well as the IBS groups. In the IBD groups, SLC5A8 was unchanged in UC but significantly increased in CD. IL-17 mRNA expression was significantly reduced in CRC and IBS groups, but unchanged in the IBD groups. PKCε mRNA was significantly increased in CRC as expected. In the IBD groups, PKCε mRNA was unchanged in CD but significantly increased in UC. In the IBS groups, PKCε mRNA in constipation –IBS (C-IBS) was significantly reduced, but unchanged in diarrhoea – IBS (D-IBS). CONCLUSIONS: β-catenin mRNA and protein expression was increased in CRC and the CRC promoting IBD groups. COX-2 protein expression was incongruent with the COX-2 mRNA expression and this may reflect homeostatic control mechanisms. High COX-2 mRNA expression in CRC and CRC promoting IBD groups may be a secondary phenomenon reflecting the inflammatory milieu, rather than a true carcinogenesis-related event. PPARγ does not appear to play a central role in early colon carcinogenesis, in spite of available literature suggesting otherwise. Butyrate transporters showed inconsistent results and for now no firm conclusions can be drawn from this. IL-17 may play a role in CAC as confirmed in this and other studies, but its role in sporadic CRC is tenuous and requires further investigation. Likewise for PKCε, upregulation is associated with increased tumourigenecity as shown in this study, however, the mechanistic pathway(s) involved is still speculative and requires further study.
- Full Text:
- Date Issued: 2013
- Authors: Fredericks, Ernst
- Date: 2013
- Subjects: Colon (Anatomy) -- Cancer , Cyclooxygenase 2 , Peroxisomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10357 , http://hdl.handle.net/10948/d1021014
- Description: Colorectal cancer (CRC) is a common disease with significant morbidity and mortality. In spite of significant advances in understanding the molecular signaling in this disorder, unanswered questions remain. Cyclooxygenase-2 (COX-2) and β-catenin have established roles in colorectal carcinogenesis, with both being upregulated early in the disease course. The role of peroxisome proliferator-activated receptor γ (PPARγ) is less clear, but has been shown to be downregulated in colon cancer models. Butyrate, a short chain fatty acid, produced by colon microbiota and transported into the colonocyte by transporter proteins, appears to be important in early carcinogenesis. The butyrate concentration is reduced in CRC and so are its transporters. Interleukin-17 (IL-17) plays a role in colitis-associated colorectal cancer (CAC), but its function in sporadic CRC is less clear. Similarly, Protein kinase C (PKC) has proven involvement in many solid tumours, including CRC, but its exact mechanistic role is still speculative. AIM: To investigate the role and possible signaling pathways of the major role players, β-catenin, COX-2 and PPARγ in early CRC. Further, to elucidate the mechanistic pathways of butyrate and its transporters, IL-17 and PKC in CRC. METHOD: Informed consent was obtained for all patients. Patients were recruited in various disease categories, including normal, irritable bowel syndrome (IBS), inflammatory bowel disease (IBD) and CRC. Colon biopsy specimens were obtained during colonoscopy and used for immunohistochemistry (IHC) and gene expression analysis of the above genes by quantitative polymerase chain reaction (qPCR). RESULTS: β-catenin mRNA and protein expression was increased in CRC and the IBD groups compared to the normal group, while it was reduced in the IBS groups. COX-2 mRNA expression showed a steady increase from normal, through IBS, IBD and CRC groups to a statistically significant degree. The COX-2 protein expression, however, did not match the mRNA expression with increased COX-2 protein expression in normal and IBS groups and reduced expression in IBD and CRC groups. PPARγ mRNA expression was unchanged in IBD and CRC groups, but significantly increased in the IBS group compared to normal. Butyrate transporter, SLC16A1 mRNA was significantly reduced in CRC, but also in the IBS groups, which was unexpected. In the IBD group, SLC16A1 mRNA was unchanged in Crohn’s disease (CD) but significantly reduced in ulcerative colitis (UC). Similarly, SLC5A8 mRNA expression was significantly reduced in the CRC as well as the IBS groups. In the IBD groups, SLC5A8 was unchanged in UC but significantly increased in CD. IL-17 mRNA expression was significantly reduced in CRC and IBS groups, but unchanged in the IBD groups. PKCε mRNA was significantly increased in CRC as expected. In the IBD groups, PKCε mRNA was unchanged in CD but significantly increased in UC. In the IBS groups, PKCε mRNA in constipation –IBS (C-IBS) was significantly reduced, but unchanged in diarrhoea – IBS (D-IBS). CONCLUSIONS: β-catenin mRNA and protein expression was increased in CRC and the CRC promoting IBD groups. COX-2 protein expression was incongruent with the COX-2 mRNA expression and this may reflect homeostatic control mechanisms. High COX-2 mRNA expression in CRC and CRC promoting IBD groups may be a secondary phenomenon reflecting the inflammatory milieu, rather than a true carcinogenesis-related event. PPARγ does not appear to play a central role in early colon carcinogenesis, in spite of available literature suggesting otherwise. Butyrate transporters showed inconsistent results and for now no firm conclusions can be drawn from this. IL-17 may play a role in CAC as confirmed in this and other studies, but its role in sporadic CRC is tenuous and requires further investigation. Likewise for PKCε, upregulation is associated with increased tumourigenecity as shown in this study, however, the mechanistic pathway(s) involved is still speculative and requires further study.
- Full Text:
- Date Issued: 2013
Strategies to provide holistic care and support to children who are AIDS orphans living in township communities
- Authors: Frood, Sharron Louise
- Date: 2013
- Subjects: Children of AIDS patients -- Care -- South Africa , Orphans -- Care -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10064 , http://hdl.handle.net/10948/d1020655
- Description: The human immunodeficiency virus/acquired immune-deficiency syndrome pandemic (HIV/AIDS) continues to increase in prevalence worldwide, particularly in South Africa. “AIDS, (Acquired Immune Deficiency Syndrome), has devastated the social and economic fabric of African societies, made orphans of a whole generation of children and become the epicentre of the HIV/AIDS pandemic” (Fassin, 2007: 76). Like the virus itself, the AIDS crisis mutates rapidly. Children who are AIDS orphans living in South Africa, as in other African countries, suffer from recurrent psychological trauma. It starts with the illness and death of their parents and is followed by cycles of poverty, malnutrition, stigma, exploitation, sickness and often sexual abuse. The figures concerning those affected, which are staggering, offer various predictions regarding the number of orphans left in the wake of the pandemic. Between 1990 and 2003, the number of orphaned children rose from fewer than 1 million to more than 12 million in sub-Saharan Africa (UNICEF, 2005: 68). South Africa is severely affected by the AIDS pandemic, with the largest number of HIV infections in the world, a total of 5.7 million (RSA, 2010: 10), affecting approximately 3.2 million women and 280 000 children aged from 0 to14 years. There is a significant variation in HIV prevalence per province, with the Eastern Cape (EC) reportedly having an average prevalence rate of 28 percent. Hence South Africa is likely to be the country with highest percentage of children orphaned by AIDS within its population. Orphanhood is a major consequence of the AIDS pandemic in South Africa with an estimated 2.2 million AIDS-orphaned children, 11,188 per 100,000 by 2015. Most children who are AIDS orphans living in township communities live predominantly uncared for and unsupported. Therefore the purpose of this research study was to develop strategies to provide care and support to children who are AIDS orphans living in township communities. To achieve the purpose of this research study, a qualitative, exploratory, descriptive and contextual design was used by the researcher to gain insight from health and social care practitioners who render care and support to children who are AIDS orphans living in these communities. The data from in-depth interviews with the health and social care practitoners was used by the researcher to develop strategies to provide care and support to children who are AIDS orphans living in township communities. The study comprised the following four phases: Phase One: During this phase, the researcher will present an overview of the current legislative framework policies at an international, national and provincial level, regarding the the rights of children living in South Africa. Phase Two: During this phase data from two research populations were collected and analysed. As the research process of this study dealt with two groups of participants, namely in group one health care practitioners and group two comprised social workers and psychologists, who work in the township communities to provide care and support to children who are AIDS orphans living in these communities. The researcher discussed each group separately in the discussion of phase two of the study. Phase Three: Comprised the themes identified in the data gathered from the transcribed in-depth interviews, the field notes as well as the reflective journals were cross-validated to ensure trustworthiness of the data which was then organised into a conceptual framework. The conceptual framework was used to clarify the relationships of the concepts and the themes identified during the research process and also used to link the gathered data to previously established models and theories (Schneider, 2004: 133). Phase Four: The last phase of the research design, focused on the development of the “Steps of progression strategies” to provide holistic care and support to children who are AIDS orphans living in township communities. This was done making use of the themes identified during data analysis and the literature sources used throughout this research process. The evaluation criteria of Chinn and Kramer (2008: 237-248) were used to evaluate the strategies. It is therefore concluded that the researcher succeeded in achieving the purpose of this study because strategies which were understandable, clear, simple, applicable and significant to nursing practice have been developed for use by the Department of Health and Department of Social Development as well as primary health and social care practitioners to provide holistic care and support to children who are AIDS orphans living in township communities in South Africa.
- Full Text:
- Date Issued: 2013
- Authors: Frood, Sharron Louise
- Date: 2013
- Subjects: Children of AIDS patients -- Care -- South Africa , Orphans -- Care -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10064 , http://hdl.handle.net/10948/d1020655
- Description: The human immunodeficiency virus/acquired immune-deficiency syndrome pandemic (HIV/AIDS) continues to increase in prevalence worldwide, particularly in South Africa. “AIDS, (Acquired Immune Deficiency Syndrome), has devastated the social and economic fabric of African societies, made orphans of a whole generation of children and become the epicentre of the HIV/AIDS pandemic” (Fassin, 2007: 76). Like the virus itself, the AIDS crisis mutates rapidly. Children who are AIDS orphans living in South Africa, as in other African countries, suffer from recurrent psychological trauma. It starts with the illness and death of their parents and is followed by cycles of poverty, malnutrition, stigma, exploitation, sickness and often sexual abuse. The figures concerning those affected, which are staggering, offer various predictions regarding the number of orphans left in the wake of the pandemic. Between 1990 and 2003, the number of orphaned children rose from fewer than 1 million to more than 12 million in sub-Saharan Africa (UNICEF, 2005: 68). South Africa is severely affected by the AIDS pandemic, with the largest number of HIV infections in the world, a total of 5.7 million (RSA, 2010: 10), affecting approximately 3.2 million women and 280 000 children aged from 0 to14 years. There is a significant variation in HIV prevalence per province, with the Eastern Cape (EC) reportedly having an average prevalence rate of 28 percent. Hence South Africa is likely to be the country with highest percentage of children orphaned by AIDS within its population. Orphanhood is a major consequence of the AIDS pandemic in South Africa with an estimated 2.2 million AIDS-orphaned children, 11,188 per 100,000 by 2015. Most children who are AIDS orphans living in township communities live predominantly uncared for and unsupported. Therefore the purpose of this research study was to develop strategies to provide care and support to children who are AIDS orphans living in township communities. To achieve the purpose of this research study, a qualitative, exploratory, descriptive and contextual design was used by the researcher to gain insight from health and social care practitioners who render care and support to children who are AIDS orphans living in these communities. The data from in-depth interviews with the health and social care practitoners was used by the researcher to develop strategies to provide care and support to children who are AIDS orphans living in township communities. The study comprised the following four phases: Phase One: During this phase, the researcher will present an overview of the current legislative framework policies at an international, national and provincial level, regarding the the rights of children living in South Africa. Phase Two: During this phase data from two research populations were collected and analysed. As the research process of this study dealt with two groups of participants, namely in group one health care practitioners and group two comprised social workers and psychologists, who work in the township communities to provide care and support to children who are AIDS orphans living in these communities. The researcher discussed each group separately in the discussion of phase two of the study. Phase Three: Comprised the themes identified in the data gathered from the transcribed in-depth interviews, the field notes as well as the reflective journals were cross-validated to ensure trustworthiness of the data which was then organised into a conceptual framework. The conceptual framework was used to clarify the relationships of the concepts and the themes identified during the research process and also used to link the gathered data to previously established models and theories (Schneider, 2004: 133). Phase Four: The last phase of the research design, focused on the development of the “Steps of progression strategies” to provide holistic care and support to children who are AIDS orphans living in township communities. This was done making use of the themes identified during data analysis and the literature sources used throughout this research process. The evaluation criteria of Chinn and Kramer (2008: 237-248) were used to evaluate the strategies. It is therefore concluded that the researcher succeeded in achieving the purpose of this study because strategies which were understandable, clear, simple, applicable and significant to nursing practice have been developed for use by the Department of Health and Department of Social Development as well as primary health and social care practitioners to provide holistic care and support to children who are AIDS orphans living in township communities in South Africa.
- Full Text:
- Date Issued: 2013
Nonlinear effects with a focus on cross phase modulation and its impact on wavelength division multiplexing optical fibre networks
- Gamatham, Romeo Reginald Gunther
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
- Authors: Gamatham, Romeo Reginald Gunther
- Date: 2013
- Subjects: Wavelength division multiplexing , Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/6302 , vital:21071
- Description: The demand for faster data transmission is ever increasing. Wavelength division multiplexing (WDM) presents as a viable solution to increase the data transmission rate significantly. WDM systems are based on the ability to transmit multiple wavelengths simultaneously down the fibre. Unlike time division multiplexing (TDM) systems, WDM systems do not increase the data transfer by increasing the transmission rate of a single channel. In WDM systems the data rate per channel remains the same, only multiple channels carry data across the link. Dense wavelength division multiplexing (DWDM) promises even more wavelengths packed together in the same fibre. This multiplication of channels increases the bandwidth capacity rapidly. Networks are looking into making use of technology that will ensure no electronic signal regeneration at any point within the DWDM network. Examples are; reconfigurable optical add/drop multiplexers (ROADM) and optical cross connect (OXC) units. These components essentially enable network operators to split, combine and multiplex optical signals carried by optical fibre. WDM allows network operators to increase the capacity of existing networks without expensive re-cabling. This provides networks with the flexibility to be upgraded to larger bandwidths and for reconfiguration of network services. Further, WDM technology opens up an opportunity of marketing flexibility to network operators, where operators not only have the option to rent out cables and fibres but wavelengths as well. Cross phase modulation (XPM) poses a problem to WDM networks. The refractive index experienced by a neighbouring optical signal, not only depends on the signal’s intensity but on the intensity of the co-propagating signal as well. This effect leads to a phase change and is known as XPM. This work investigates the characteristics of XPM. It is shown that, in a two channel WDM network, a probe signal’s SOP can be steered by controlling a high intensity pump signal’s SOP. This effect could be applied to make a wavelength converter. Experimental results show that the degree of polarization (DOP) of a probe signal degrades according to a mathematical model found in literature. The pump and probe signals are shown to experience maximum interaction, for orthogonal probe-pump SOP vector orientations. This may be problematic to polarization mode dispersion compensators. Additionally, experimental results point out that the SOP of a probe signal is much more active in the presence of a high intensity pump, as compared to the single signal transmission scenario.
- Full Text:
- Date Issued: 2013
Characterisation and biotic classification of Eastern Cape mixed substrate shores
- Authors: Garner, Cornelia Johanna
- Date: 2013
- Subjects: Coastal sediments -- South Africa -- Eastern Cape , Coastal biodiversity --- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10641 , http://hdl.handle.net/10948/d1020825
- Description: A significant proportion of the South African coastline is composed of both soft (mostly sand) and hard (mostly bedrock) substrata, i.e. “mixed”. This study described and classified macrobenthic assemblages of 20 Eastern Cape mixed substrate shores that differed in shore topography and the extent and position of intertidal rock and sand. A stratified random approach was used. Species richness, composition, abundance and environmental variables were determined. Commonly used beach indices were calculated. A total of 78 macrofaunal and 172 macroalgal species from rock substrate assemblages and 205 macrofauna species from sediment were recorded. Total species richness and richness per substratum exceeded that of sandy beaches devoid of rock and rocky shores with no sand. Rhodophyta were the most diverse and abundant algae, dominating all low-elevation rock surfaces as midlittoral and infralittoral turfs. Chlorophyta diversity was higher than at rocky shores, contributing more to cover-abundance at study sites and in microhabitats with an increased sand load. Sessile macrofauna species richness and abundance was lower than that of rocky shores. Polychaetes and crustaceans were the most diverse and abundant beach infauna. Species richness of both substrates declined from the low shore towards the high shore, but abundance trends varied substantially. The presence and extent of an intertidal biotope/subzone at either substrate depended on substrate availability.The supralittoral fringe in both substrate types was most often affected. Zonal overlap was evident on rock substrate: assemblages of raised midlittoral rock surfaces were enriched by species from lower surfaces sometimes leading to elimination of character taxa. Classification and ordination identified three potential mixed substrate shore biotic types: Biotic type A (Jania-Corallina- Polysiphonia turf) was characterised by robustly-textured algal turfs, a lowered predominance and diversity of polychaetes and an increase in crustacean abundance and diversity in sediment. Biotic type B (Polysiphonia-Tayloriella-Caulacanthus turf) had intermediately and biotic type C (Arthrocardia-Laurencia turf) the most sheltered eulittoral zones and beaches. DCCA identified the major environmental parameters affecting the macrobiota as: the level of wave energy, geological control of waves by hard substrate, sediment grain size and sediment inundation. A strong cross-shore wave attenuation results in sheltered sediments and midshore rock surfaces. Beach macrofauna were highly variable and diverse, which directly opposes previous perceptions about the sediment-bound biota of mixed substrate shores. The hierarchical cluster analysis produced a biotic classification of mixed substrate shores that was indicative of a biotic response to the total effects of leading environmental parameters. Macrobenthos of rock surfaces and sediment therefore showed potential to be used as an alternative or complementary to physical characteristics in classifying mixed substrate shores.
- Full Text:
- Date Issued: 2013
- Authors: Garner, Cornelia Johanna
- Date: 2013
- Subjects: Coastal sediments -- South Africa -- Eastern Cape , Coastal biodiversity --- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10641 , http://hdl.handle.net/10948/d1020825
- Description: A significant proportion of the South African coastline is composed of both soft (mostly sand) and hard (mostly bedrock) substrata, i.e. “mixed”. This study described and classified macrobenthic assemblages of 20 Eastern Cape mixed substrate shores that differed in shore topography and the extent and position of intertidal rock and sand. A stratified random approach was used. Species richness, composition, abundance and environmental variables were determined. Commonly used beach indices were calculated. A total of 78 macrofaunal and 172 macroalgal species from rock substrate assemblages and 205 macrofauna species from sediment were recorded. Total species richness and richness per substratum exceeded that of sandy beaches devoid of rock and rocky shores with no sand. Rhodophyta were the most diverse and abundant algae, dominating all low-elevation rock surfaces as midlittoral and infralittoral turfs. Chlorophyta diversity was higher than at rocky shores, contributing more to cover-abundance at study sites and in microhabitats with an increased sand load. Sessile macrofauna species richness and abundance was lower than that of rocky shores. Polychaetes and crustaceans were the most diverse and abundant beach infauna. Species richness of both substrates declined from the low shore towards the high shore, but abundance trends varied substantially. The presence and extent of an intertidal biotope/subzone at either substrate depended on substrate availability.The supralittoral fringe in both substrate types was most often affected. Zonal overlap was evident on rock substrate: assemblages of raised midlittoral rock surfaces were enriched by species from lower surfaces sometimes leading to elimination of character taxa. Classification and ordination identified three potential mixed substrate shore biotic types: Biotic type A (Jania-Corallina- Polysiphonia turf) was characterised by robustly-textured algal turfs, a lowered predominance and diversity of polychaetes and an increase in crustacean abundance and diversity in sediment. Biotic type B (Polysiphonia-Tayloriella-Caulacanthus turf) had intermediately and biotic type C (Arthrocardia-Laurencia turf) the most sheltered eulittoral zones and beaches. DCCA identified the major environmental parameters affecting the macrobiota as: the level of wave energy, geological control of waves by hard substrate, sediment grain size and sediment inundation. A strong cross-shore wave attenuation results in sheltered sediments and midshore rock surfaces. Beach macrofauna were highly variable and diverse, which directly opposes previous perceptions about the sediment-bound biota of mixed substrate shores. The hierarchical cluster analysis produced a biotic classification of mixed substrate shores that was indicative of a biotic response to the total effects of leading environmental parameters. Macrobenthos of rock surfaces and sediment therefore showed potential to be used as an alternative or complementary to physical characteristics in classifying mixed substrate shores.
- Full Text:
- Date Issued: 2013
Towards the development of a mycoinsecticide to control white grubs (Coleoptera: Scarabaeidae) in South African sugarcane
- Authors: Goble, Tarryn Anne
- Date: 2013
- Subjects: Insecticides -- Environmental aspects Insecticides -- Toxicology Beetles -- South Africa -- KwaZulu-Natal Beetles -- Control -- South Africa -- KwaZulu-Natal Coleophoridae -- South Africa -- KwaZulu-Natal Scarabaeidae -- South Africa -- KwaZulu-Natal Sugarcane -- Diseases and pests -- South Africa -- KwaZulu-Natal Sugarcane -- Diseases and pests -- Control -- South Africa -- KwaZulu-Natal , Insecticides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5586 , http://hdl.handle.net/10962/d1001748
- Description: In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).
- Full Text:
- Date Issued: 2013
- Authors: Goble, Tarryn Anne
- Date: 2013
- Subjects: Insecticides -- Environmental aspects Insecticides -- Toxicology Beetles -- South Africa -- KwaZulu-Natal Beetles -- Control -- South Africa -- KwaZulu-Natal Coleophoridae -- South Africa -- KwaZulu-Natal Scarabaeidae -- South Africa -- KwaZulu-Natal Sugarcane -- Diseases and pests -- South Africa -- KwaZulu-Natal Sugarcane -- Diseases and pests -- Control -- South Africa -- KwaZulu-Natal , Insecticides
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5586 , http://hdl.handle.net/10962/d1001748
- Description: In the KwaZulu-Natal (KZN) Midlands North region of South Africa, the importance and increased prevalence of endemic scarabaeids, particularly Hypopholis sommeri Burmeister and Schizonycha affinis Boheman (Coleoptera: Melolonthinae), as soil pests of sugarcane, and a need for their control was established. The development of a mycoinsecticide offers an environmentally friendly alternative to chemical insecticides. The identification of a diversity of white grub species, in two Scarabaeidae subfamilies, representing seven genera were collected in sugarcane as a pest complex. Hypopholis sommeri and S. affinis were the most prevalent species. The increased seasonal abundances, diversity and highly aggregated nature of these scarabaeid species in summer months, suggested that targeting and control strategies for these pests should be considered in this season. Increased rainfall, relative humidity and soil temperatures were linked to the increased occurrence of scarab adults and neonate grubs. Beauveria brongniartii (Saccardo) Petch epizootics were recorded at two sites in the KZN Midlands North on H. sommeri. Seventeen different fluorescently-labelled microsatellite PCR primers were used to target 78 isolates of Beauveria sp. DNA. Microsatellite data resolved two distinct clusters of Beauveria isolates which represented the Beauveria bassiana senso stricto (Balsamo) Vuillemin and B. brongniartii species groups. These groupings were supported by two gene regions, the nuclear ribosomal Internal Transcribed Spacer (ITS) and the nuclear B locus (Bloc) gene of which 23 exemplar Beauveria isolates were represented and sequenced. When microsatellite data were analysed, 26 haplotypes among 58 isolates of B. brongniartii were distinguished. Relatively low levels of genetic diversity were detected in B. brongniartii and isolates were shown to be closely related. There was no genetic differentiation between the two sites, Harden Heights and Canema in the KZN Midlands North. High gene flow from swarming H. sommeri beetles is the proposed mechanism for this lack of genetic differentiation between populations. Microsatellite analyses also showed that B. brongniartii conidia were being cycled from arboreal to subterranean habitats in the environment by H. sommeri beetles. This was the first record of this species of fungus causing epizootics on the larvae and adults of H. sommeri in South Africa. The virulence of 21 isolates of Beauveria brongniartii and two isolates of B. bassiana were evaluated against the adults and larvae of S. affinis and the adults of H. sommeri and Tenebrio molitor Linnaeus (Coleoptera: Tenebrionidae). Despite being closely-related, B. brongniartii isolates varied significantly in their virulence towards different hosts and highlighted the host specific nature of B. brongniartii towards S. affinis when compared to B. bassiana. Adults of S. affinis were significantly more susceptible to B. brongniartii isolates than the second (L2) or third instar (L3) grubs. The median lethal time (LT₅₀) of the most virulent B. brongniartii isolate (C13) against S. affinis adults was 7.8 days and probit analysis estimated a median lethal concentration (LC₅₀) of 4.4×10⁷ conidia/ml⁻¹. When L2 grubs were treated with a concentration of 1.0×10⁸ conidia/ml⁻¹, B. brongniartii isolates HHWG1, HHB39A and C17 caused mortality in L2 grubs within 18.4-19.8 days (LT₅₀). Beauveria brongniartii isolate HHWG1 was tested against the L3 grubs of S. affinis at four different concentrations. At the lowest concentration (1×10⁶ conidia/ml⁻¹), the LT₅₀ was 25.8 days, and at the highest concentration (1×10⁹ conidia/ml⁻¹) the LT₅₀ dropped to 15.1 days. The persistence of B. bassiana isolate 4222 formulated on rice and wheat bran and buried at eight field sites in the KZN Midlands North was evaluated by plating out a suspension of treated soil onto a selective medium. All eight field sites showed a significant decline in B. bassiana CFUs per gram of soil over time, with few conidia still present in the samples after a year. Greater declines in CFUs were observed at some sites but there were no significant differences observed in the persistence of conidia formulated on rice or wheat bran as carriers. Overall, poor persistence of B. bassiana isolate 4222 was attributed to suboptimum temperatures, rainfall, which rapidly degraded the nutritive carriers, attenuated fungal genotype and the action of antagonistic soil microbes. Growers’ perceptions of white grubs as pests and the feasibility of a mycoinsecticide market were evaluated by means of a semi-structured questionnaire. The study showed that the reduced feasibility of application, general lack of potential demand for a product, high cost factors and most importantly, the lack of pest perception, were factors which would negatively affect the adoption of a granular mycoinsecticide. Growers however exhibited a positive attitude towards mycoinsecticides, and showed all the relevant attributes for successful technology adoption. It is recommended that because B. brongniartii epizootics were recorded on target pests which indicated good host specificity, dispersal ability and persistence of the fungus in the intended environment of application; that a mycoinsecticide based on this fungal species be developed. What will likely increase adoption and success of a mycoinsecticide is collaboration between various industries partners to increases market potential in other crops such as Acacia mearnsii De Wild (Fabales: Fabaceae).
- Full Text:
- Date Issued: 2013
"Abject dictatorship of the flesh" : corporeality in the fiction of Patrick White
- Authors: Grogan, Bridget Meredith
- Date: 2013
- Subjects: White, Patrick, 1912-1990 -- Criticism and interpretation Human body in literature Dualism in literature Human body -- Social aspects Body image -- Social aspects Australian fiction -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2166 , http://hdl.handle.net/10962/d1001554
- Description: Thesis embargoed for an indefinite period - full text not available
- Full Text: false
- Date Issued: 2013
- Authors: Grogan, Bridget Meredith
- Date: 2013
- Subjects: White, Patrick, 1912-1990 -- Criticism and interpretation Human body in literature Dualism in literature Human body -- Social aspects Body image -- Social aspects Australian fiction -- 20th century -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2166 , http://hdl.handle.net/10962/d1001554
- Description: Thesis embargoed for an indefinite period - full text not available
- Full Text: false
- Date Issued: 2013
Invasion of Lantana into India: analyzing introduction, spread, human adaptations and management
- Hari Krishnan, Ramesh Kannan
- Authors: Hari Krishnan, Ramesh Kannan
- Date: 2013
- Subjects: Lantana -- India Weeds -- Control -- India Plant introduction -- India Natural resources -- India Botany, Economic -- India Botany -- Social aspects -- India
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4728 , http://hdl.handle.net/10962/d1001756
- Description: Objectives and Research Questions 1. To reconstruct the history of invasion of Lantana in India from where, by who, and when was Lantana species introduced into India?, given its long history in the country, is it still spreading or has it become more or less stable? 2. To study the human adaptation to Lantana invasion: socioeconomic causes and consequences of the use of Lantana as an alternative source of livelihood for forest dependent communities in southern India; how have local communities adapted to the invasion?; what are the key determinants that may have driven communities to use Lantana?; what are the economic consequences of the use of Lantana by local communities? 3. To critically review local practices and forest policy for the management of Lantana in southern India.; how has the use of Lantana by local communities impacted its local regeneration?; does the use of Lantana in local context have implications for its management?; what has been the role of the Forest Department and its policies in managing Lantana?
- Full Text:
- Date Issued: 2013
- Authors: Hari Krishnan, Ramesh Kannan
- Date: 2013
- Subjects: Lantana -- India Weeds -- Control -- India Plant introduction -- India Natural resources -- India Botany, Economic -- India Botany -- Social aspects -- India
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4728 , http://hdl.handle.net/10962/d1001756
- Description: Objectives and Research Questions 1. To reconstruct the history of invasion of Lantana in India from where, by who, and when was Lantana species introduced into India?, given its long history in the country, is it still spreading or has it become more or less stable? 2. To study the human adaptation to Lantana invasion: socioeconomic causes and consequences of the use of Lantana as an alternative source of livelihood for forest dependent communities in southern India; how have local communities adapted to the invasion?; what are the key determinants that may have driven communities to use Lantana?; what are the economic consequences of the use of Lantana by local communities? 3. To critically review local practices and forest policy for the management of Lantana in southern India.; how has the use of Lantana by local communities impacted its local regeneration?; does the use of Lantana in local context have implications for its management?; what has been the role of the Forest Department and its policies in managing Lantana?
- Full Text:
- Date Issued: 2013
An exploration of conditions enabling and constraining the infusion of service-learning into the curriculum at a South African research led university
- Authors: Hlengwa, Amanda Immaculate
- Date: 2013
- Subjects: Rhodes University -- Curricula -- Evaluation Service learning -- Research -- South Africa Education, Higher -- Curricula -- South Africa -- Evaluation Curriculum planning -- Research -- South Africa Experiential learning -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1888 , http://hdl.handle.net/10962/d1006036
- Description: Drawing on critical realist philosophy as a meta-theoretical framework, this study explores the conditions that enable and constrain the infusion of service-learning in university curricula. In this study, four discipline-based cases are analysed within the context of an overarching case of one South African university. The study reports on case study research into four disciplines, broadly representing the disciplinary array offered at Rhodes University, a small traditional research-intensive university in South Africa – four cases are thus embedded within a larger over-arching case. Margret Archer’s analytical dualism is used as an analytical lens for the inquiry. It offers tools for examining the conditions for the emergence of service learning and the form it takes in each case. Archer’s framework requires the artificial separation of structural, cultural and agential mechanisms for analytical purposes in order to establish the dominant factors impacting on the infusion of service-learning in curricula. An analysis of the interplay between structure, culture and agency uncovers insights into the conditions that enable or constrain the adoption of service learning as a pedagogic tool in specific disciplines. Curriculum decision-making is a central consideration in this study. Basil Bernstein’s theory of cultural transmission provides an external language of description to theorise the pedagogic choices made in specific contexts. This body of theory provides analytical tools for generating nuanced explanations of the significance of knowledge and curriculum structures as enabling and constraining mechanisms when pedagogic decisions are made. The study shows that the nature of the discipline has a significant influence on the emergence of service-learning and the form it takes in each context. Key agents draw on available structural and cultural mechanisms to either maintain the status quo or they exercise their personal properties and powers to mitigate existing conditions. The first case examines the emergence of service-learning in a ‘hard pure’ discipline where structural and cultural conditions constrain the emergence of innovative pedagogic tools. In this case a key agent draws on a confluence of personal, structural and cultural emergent properties to initiate a service-learning course at the honours level. Factors that make service-learning possible in this case include the key agent’s seniority within the institution, his status as a prolific researcher, the possibilities for application of disciplinary knowledge, and a strong institutional discourse of service to society (RU in Society) and an institutional and departmental discourse privileging academic freedom. In the second case the conditions in the ‘hard applied’ discipline are largely enabling, however the emergence of service-learning is facilitated by the interplay of the following agential, structural and cultural emergent properties: corporate agency taking advantage of the outward focus of the discipline (a region in Bernsteinian terms) and drawing on what is termed the RU in Society discourse. The third case represents a ‘soft pure’ discipline, where service-learning does not emerge within the formal curriculum, but in a largely marginalised departmental outreach programme. This discipline is inward facing and although its knowledge base draws on challenges and phenomena in society, it remains at an esoteric level accessible mainly to the discipline community. Agents in this department draw on the insular structure of the discipline, in conjunction with the strong Academic Freedom discourse to develop a form of service-learning that furthers disciplinary aims, albeit within the context of limited engagement beyond the boundaries of the discipline and the institution. In the case of the ‘soft applied’ discipline the structural and cultural conditions are largely enabling. However the emergence of service-learning in this discipline relies on the advocacy of a powerful social agent in the department with an interest in socially equitable practice; she draws on the RU in Society discourse to promote direct engagement with communities beyond the university boundaries. The study is set in a research-intensive university and it is perhaps not surprising that the service-learning courses in three of the four cases are framed by research projects. This suggests that in the context of this kind of institution it may be imperative to draw on research activities as the basis of infusing service-learning in the curriculum. The findings of this study challenge the implicit assumption in policy documents that it is possible to institute service-learning in all disciplines.
- Full Text:
- Date Issued: 2013
- Authors: Hlengwa, Amanda Immaculate
- Date: 2013
- Subjects: Rhodes University -- Curricula -- Evaluation Service learning -- Research -- South Africa Education, Higher -- Curricula -- South Africa -- Evaluation Curriculum planning -- Research -- South Africa Experiential learning -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1888 , http://hdl.handle.net/10962/d1006036
- Description: Drawing on critical realist philosophy as a meta-theoretical framework, this study explores the conditions that enable and constrain the infusion of service-learning in university curricula. In this study, four discipline-based cases are analysed within the context of an overarching case of one South African university. The study reports on case study research into four disciplines, broadly representing the disciplinary array offered at Rhodes University, a small traditional research-intensive university in South Africa – four cases are thus embedded within a larger over-arching case. Margret Archer’s analytical dualism is used as an analytical lens for the inquiry. It offers tools for examining the conditions for the emergence of service learning and the form it takes in each case. Archer’s framework requires the artificial separation of structural, cultural and agential mechanisms for analytical purposes in order to establish the dominant factors impacting on the infusion of service-learning in curricula. An analysis of the interplay between structure, culture and agency uncovers insights into the conditions that enable or constrain the adoption of service learning as a pedagogic tool in specific disciplines. Curriculum decision-making is a central consideration in this study. Basil Bernstein’s theory of cultural transmission provides an external language of description to theorise the pedagogic choices made in specific contexts. This body of theory provides analytical tools for generating nuanced explanations of the significance of knowledge and curriculum structures as enabling and constraining mechanisms when pedagogic decisions are made. The study shows that the nature of the discipline has a significant influence on the emergence of service-learning and the form it takes in each context. Key agents draw on available structural and cultural mechanisms to either maintain the status quo or they exercise their personal properties and powers to mitigate existing conditions. The first case examines the emergence of service-learning in a ‘hard pure’ discipline where structural and cultural conditions constrain the emergence of innovative pedagogic tools. In this case a key agent draws on a confluence of personal, structural and cultural emergent properties to initiate a service-learning course at the honours level. Factors that make service-learning possible in this case include the key agent’s seniority within the institution, his status as a prolific researcher, the possibilities for application of disciplinary knowledge, and a strong institutional discourse of service to society (RU in Society) and an institutional and departmental discourse privileging academic freedom. In the second case the conditions in the ‘hard applied’ discipline are largely enabling, however the emergence of service-learning is facilitated by the interplay of the following agential, structural and cultural emergent properties: corporate agency taking advantage of the outward focus of the discipline (a region in Bernsteinian terms) and drawing on what is termed the RU in Society discourse. The third case represents a ‘soft pure’ discipline, where service-learning does not emerge within the formal curriculum, but in a largely marginalised departmental outreach programme. This discipline is inward facing and although its knowledge base draws on challenges and phenomena in society, it remains at an esoteric level accessible mainly to the discipline community. Agents in this department draw on the insular structure of the discipline, in conjunction with the strong Academic Freedom discourse to develop a form of service-learning that furthers disciplinary aims, albeit within the context of limited engagement beyond the boundaries of the discipline and the institution. In the case of the ‘soft applied’ discipline the structural and cultural conditions are largely enabling. However the emergence of service-learning in this discipline relies on the advocacy of a powerful social agent in the department with an interest in socially equitable practice; she draws on the RU in Society discourse to promote direct engagement with communities beyond the university boundaries. The study is set in a research-intensive university and it is perhaps not surprising that the service-learning courses in three of the four cases are framed by research projects. This suggests that in the context of this kind of institution it may be imperative to draw on research activities as the basis of infusing service-learning in the curriculum. The findings of this study challenge the implicit assumption in policy documents that it is possible to institute service-learning in all disciplines.
- Full Text:
- Date Issued: 2013
Petrogenesis and metallogenesis of the Panzhihua Fe-Ti oxide ore-bearing mafic layered intrusion, SW China
- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
- Full Text:
- Date Issued: 2013
- Authors: Howarth, Geoffrey Hamilton
- Date: 2013
- Subjects: Petrogenesis Metallogeny Intrusions (Geology) -- China -- Panzhihua Metallogenic provinces -- China -- Panzhihua Igneous rocks -- China -- Panzhihua Geochemistry Iron Titanium Oxides Ores Magmas
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4915 , http://hdl.handle.net/10962/d1001810
- Description: The Panzhihua intrusion is one of several large Fe-Ti oxide ore bearing intrusions related to the major flood volcanism of the Emeishan Large Igneous Province (ELIP), SW China. The Panzhihua intrusion in particular has recently become the focus of numerous studies owing to the excellent exposure in large open pit mining operations. The formation of Fe-Ti oxide ore layers has been the focus of these studies and has become a somewhat controversial topic with three separate models currently proposed for ore formation. The gabbroic Panzhihua intrusion extends for ± 19 km along strike, has a maximum thickness of 3000 m and hosts extensive (up to 60 m thick) Fe-Ti oxide ore layers in the lower portions of the intrusion. The intrusion has been divided into five zones: marginal zone (MGZ), lower zone (LZ), middle zone A (MZa), middle zone b (MZb) and the upper zone (UZ). The gabbroic rocks are comprised of plagioclase, clinopyroxene and interstitial Fe-Ti oxides with minor olivine. Apatite is present within the MZb only and shows no correlation with Fe-Ti oxide ore layers. Fe-Ti oxides are present throughout the stratigraphy of the intrusion. This is unlike typical layered intrusions where significant Fe-enrichment through fractionation of Fe-poor silicate phases (i.e. plagioclase) is required before Fe-Ti oxide saturation. There are no oxide-free cumulate rocks at the Panzhihua intrusion, implying either an evolved parent magma or very high Fe content of the source rocks. I present here new mineral composition data, whole-rock major and trace element geochemistry along with whole-rock Sr-Nd isotopes and PGEs in order to constrain the evolution of the Panzhihua parent magma en route from source to chamber and the formation of Fe-Ti oxide ore layers. Furthermore an initial pilot study using O-isotope data is conducted on Ti-magnetite and plagioclase separates from gabbroic vs. ore rocks. Results are coupled with detailed thermodynamic modeling using the software PELE in order to further constrain Fe-Ti oxide ore layer formation. The intrusion is characterised by extreme depletion of PGEs relative to the coeval flood basalts and picrites. High Cu/Pd and Pd/Pt imply two separate stages of S-saturated and S-undersaturated depletion of PGEs. Pd is highly compatible in sulphide and is quickly scavenged by sulphide liquids resulting in an increase in Cu/Pd of the residual liquid. Furthermore decoupling of Pd and Pt can be achieved by either late stage hydrothermal alteration or through S-undersaturated stage of PGE depletion where Pt is scavenged by Pt-rich alloys or oxide minerals. I show that the latter is more likely. Fractionation modeling suggests that the Panzhihua parent magma formed at depth from original picritic magma. This is consistent with several other recent studies on other layered intrusions of the ELIP. Sr-Nd isotopic ratios indicate very little crustal contamination has occurred en route to the current chamber. Sr and Nd concentrations of footwall rocks are too low to produce any significant change in initial Sr and Nd isotopic ratios of the intruding basaltic magmas, indicating that crustal contamination will not be indicated by Sr-Nd isotopic ratios. Gradational change in the Sr-Nd isotope ratios across the MGZ provides strong evidence for formation in an open system by multiple replenishments of progressively less contaminated magmas from depth. Contamination is difficult to constrain but must be occurring prior to emplacement at the current level (low Sr and Nd contents of footwall). A gradational upward decrease in highly incompatible element across the MGZ can then be explained by continuous magma flow, which effectively removes the evolved intercumulus liquids from the growing cumulate pile at the base of the chamber. The initial stages of formation of the Panzhihua intrusion are interpreted to result from prolonged low volume pulses of magma into a slowly opening chamber. The timing of Fe-Ti oxide crystallisation is fundamental in the understanding of the petrogenesis of ore layers. Distinct geochemical variation in whole-rock Fe2O3/TiO2 and Zr/Nb indicates that Timagnetite is the dominant oxide within the lower ± 270 m of the intrusion whereas above this level both Ti-magnetite and ilmenite are present as cumulus phases. This is interpreted to indicate a variation in the fO2 where the lower intrusion crystallises at higher fO2 relative to that above this level. Silicates within the ore layers, in particular plagioclase, are highly embayed and resorped where in contact with Fe-Ti oxides. This characteristic of the silicate grains implies early crystallisation prior to Fe-Ti oxides with subsequent disequilibrium conditions resulting in resorption. Furthermore distinct reaction rims of kaersutite amphibole, Fo-enriched olivine, An-enriched plagioclase and pleonaste are observed. The abundance of amphibole suggests H2O involvement in this reaction and consumption of silicates. A model for parent magma crystallisation at various H2O contents indicates that plagioclase crystallisation temperature is very sensitive to H2O content of the parent magma. Plagioclase crystallises early for “dry” compositions but significantly later for “wet” compositions. Fe-Ti oxide ore layers are generally well layered, contain gabbroic xenoliths and are observed raversing/cross-cutting the cumulate stratigraphy. I present here a new model for ore layer formation in order to account for these distinct features of the ore layers. A model invoking multiple replenishments of magma with variable oxide microphenocryst content, H2O content and volume is proposed. Magma evolving in the plumbing system and fed to the Panzhihua chamber is variably enriched in H2O, which results in significantly different crystallisation paths. High H2O magmas (> 2 wt %) crystallise Fe-Ti oxides early whereas low H2O magmas (< 1 wt %) crystallise oxides late. Early pulses of H2O-poor magma crystallise a sequence of plag+cpx+Fe-Ti oxide (±ol). Later pulses of H2Orich magma subsequently intrude the partially crystallised cumulate sequence incorporating and consuming previously crystallised silicates with subsequent early crystallisation of Ti-magnetite and formation of ore layers. H2O-rich magmas likely have suspended Ti-magnetite microphenocrysts as well, which crystallise at depth in the plumbing system. This model can account for the various characteristic features of the Fe-Ti oxide ore layers at the Panzhihua intrusion as well as other Fe-Ti oxide ore bearing intrusions in the region.
- Full Text:
- Date Issued: 2013
The contribution of submerged macrophytes and macroalgae to nutrient cycling in the Great Brak Estuary
- Authors: Human, Lucienne Ryno Daniel
- Date: 2013
- Subjects: Nutrient cycles -- South Africa -- Great Brak Estuary , Microalgae -- South Africa -- Great Brak Estuary , Estuarine ecology -- South Africa -- Great Brak Estuary
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10364 , http://hdl.handle.net/10948/d1021102
- Description: An ecological reserve study by the Department of Water Affairs on the Great Brak Estuary stated that there was a need to determine how much nitrogen and phosphorus was flowing through the estuary as well as how effective the macroalgae were at removing N and P. The objective of this study was to investigate the physico-chemical characteristics in the estuary and the influence of these on the submerged macrophytes and macroalgae. A nutrient budget for the estuary was developed in order to quantify the contribution of the submerged macrophytes and macroalgae relative to other contributing sources. The Wolwedans Dam located 3 km upstream from the estuary has reduced the amount of freshwater flow to the estuary by as much as 56 percent. The estuary has been allocated 2 x 106 m3 per annum of freshwater (ecological reserve) that is used to breach the mouth once or twice a year in spring or summer. Even though this water has been made available it is not sufficient to flush the estuary. Reduced flushing has led to an accumulation of organic matter and degradation in the water quality. Physico-chemical measurements between September 2010 and July 2012 showed that dissolved oxygen values were generally below 6 mg l-1. The average NH4+ concentration in the estuary was 7 μM and increased with depth to 12 μM at 2 m depths. Concentrations >45 μM were found in February and April 2011 at the 5 m deep hole at 3.4 km upstream. Negative correlations between dissolved oxygen and NH4+ during November 2010, February 2011, April 2011 and July 2011 (r = -0.68; -0.67; -0.63; -0.96) indicated that remineralisation of organic matter had occurred. Soluble reactive phosphorus (SRP) followed a similar trend to the NH4+ and was generally below 1 μM in the water column for most months, and had peaks at 1.0 km and 3.4 km in the bottom water. The abundance of submerged macrophytes and macroalgae below the N2 bridge were mostly influenced by mouth state and river inflow. During the closed phase the dominant macroalga Cladophora glomerata had an area cover ranging from 3000 to 6000 m2 while Zostera capensis and Ruppia cirrhosa covered an area of 2000 to 3500 m2 and 1500 to 2900 m2, respectively. After an artificial breach in February 2011, water drained out of the estuary leaving the alga stranded on the marshes and as the flood tide entered the macroalga was once again redistributed in the lower reaches. The alga utilised the available nutrients in the water column and expanded its area cover from 35000 m2 in February 2011 to 64000 m2 in March 2011. However, after the floods in June 2011, Cladophora glomerata had been washed out of the system while the submerged macrophytes responded positively extending their area cover. By comparing the artificial breach with the natural breach, and the effect on the estuary, an important observation was highlighted. Increasing the current allocated ecological reserve, and using a larger volume of water to breach the mouth artificially, would result in better scouring of sediment and associated organic matter out of the estuary. This would enable better oxygenation of the water column, reduce remineralisation and minimise algal blooms.
- Full Text:
- Date Issued: 2013
- Authors: Human, Lucienne Ryno Daniel
- Date: 2013
- Subjects: Nutrient cycles -- South Africa -- Great Brak Estuary , Microalgae -- South Africa -- Great Brak Estuary , Estuarine ecology -- South Africa -- Great Brak Estuary
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10364 , http://hdl.handle.net/10948/d1021102
- Description: An ecological reserve study by the Department of Water Affairs on the Great Brak Estuary stated that there was a need to determine how much nitrogen and phosphorus was flowing through the estuary as well as how effective the macroalgae were at removing N and P. The objective of this study was to investigate the physico-chemical characteristics in the estuary and the influence of these on the submerged macrophytes and macroalgae. A nutrient budget for the estuary was developed in order to quantify the contribution of the submerged macrophytes and macroalgae relative to other contributing sources. The Wolwedans Dam located 3 km upstream from the estuary has reduced the amount of freshwater flow to the estuary by as much as 56 percent. The estuary has been allocated 2 x 106 m3 per annum of freshwater (ecological reserve) that is used to breach the mouth once or twice a year in spring or summer. Even though this water has been made available it is not sufficient to flush the estuary. Reduced flushing has led to an accumulation of organic matter and degradation in the water quality. Physico-chemical measurements between September 2010 and July 2012 showed that dissolved oxygen values were generally below 6 mg l-1. The average NH4+ concentration in the estuary was 7 μM and increased with depth to 12 μM at 2 m depths. Concentrations >45 μM were found in February and April 2011 at the 5 m deep hole at 3.4 km upstream. Negative correlations between dissolved oxygen and NH4+ during November 2010, February 2011, April 2011 and July 2011 (r = -0.68; -0.67; -0.63; -0.96) indicated that remineralisation of organic matter had occurred. Soluble reactive phosphorus (SRP) followed a similar trend to the NH4+ and was generally below 1 μM in the water column for most months, and had peaks at 1.0 km and 3.4 km in the bottom water. The abundance of submerged macrophytes and macroalgae below the N2 bridge were mostly influenced by mouth state and river inflow. During the closed phase the dominant macroalga Cladophora glomerata had an area cover ranging from 3000 to 6000 m2 while Zostera capensis and Ruppia cirrhosa covered an area of 2000 to 3500 m2 and 1500 to 2900 m2, respectively. After an artificial breach in February 2011, water drained out of the estuary leaving the alga stranded on the marshes and as the flood tide entered the macroalga was once again redistributed in the lower reaches. The alga utilised the available nutrients in the water column and expanded its area cover from 35000 m2 in February 2011 to 64000 m2 in March 2011. However, after the floods in June 2011, Cladophora glomerata had been washed out of the system while the submerged macrophytes responded positively extending their area cover. By comparing the artificial breach with the natural breach, and the effect on the estuary, an important observation was highlighted. Increasing the current allocated ecological reserve, and using a larger volume of water to breach the mouth artificially, would result in better scouring of sediment and associated organic matter out of the estuary. This would enable better oxygenation of the water column, reduce remineralisation and minimise algal blooms.
- Full Text:
- Date Issued: 2013