Exploring pre-service teachers’ reflective practice in the context of video-based lesson analysis
- Authors: Chikiwa, Samukeliso
- Date: 2020-04-30
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/355357 , vital:64492
- Description: This study explored the development of reflective practice in foundation phase pre-service teachers in the context of video-based lesson analysis at a university in South Africa. The study was conducted in the field of mathematics education, responding to the urgent need to equip pre-service South African teachers with the knowledge and skills for effective mathematics teaching. The research is foregrounded by the continuing poor performance of South African learners in mathematics at all levels of education in the country, which has been linked to the inadequate knowledge and skills of mathematics teachers. Pre-service teacher education is putting considerable effort into improving the preparation of mathematics teachers and developing their ability to reflect on their teaching practice is one of the strategies being employed for this purpose. Research has demonstrated the importance of reflective practice (RP) in both developing and extending teachers’ mathematical knowledge for teaching. This study therefore contributes to current research that supports the development of RP as a professional skill for promoting the acquisition of knowledge for teaching in pre-service teacher education. The study adopted a qualitative case study approach with two phases of data collection. In Phase 1 I collected and analysed three sets of 19 pre-service teachers’ written reflections to establish the nature of the reflections that they developed when analysing video-recorded mathematics lessons of experienced teachers’ practice. Phase 2 was conducted with four PSTs who reflected on video-recorded mathematics lessons of their own practice, and similarly sought to investigate the nature of the reflections they developed when reflecting on practice. The four PSTs wrote one set of reflections on their own lessons, went through three sessions of facilitator-guided reflections, then wrote another set of reflections to establish if the support provided in small group facilitator-guided sessions improved their reflections. Iterative content analysis was employed to analyse the PSTs’ written reflections, using an analytic tool that I developed for this purpose through merging Lee’s (2007) and Muir and Beswick’s (2007) levels of reflection frameworks. My model had four levels of reflection: description, explanation, suggestion and reflectivity. The names of each of the levels connect to the key indicator for that level. PSTs’ written reflections were coded and analysed according to these levels. The study found that PSTs’ initial reflections were mostly description of general classroom events with little reflection at the levels of explanation and suggestion, and an absence of reflectivity. Most reflections focused on general events in the lesson rather than mathematical events, even though the six lens framework they were given to guide their reflections prompted them to steer their attention towards mathematical events. The second and third sets of reflections, although mostly still at level 1, showed some shifts towards explanation and suggestion, although an increased focus on mathematical events though reflectivity was still largely absent. No PST reached the fourth level of reflectivity in Phase 1. However, in Phase 2, the PSTs’ reflections after the three small group facilitator-guided sessions included some evidence of reflectivity. The findings suggest the need for pre-service teacher educators to make a concerted effort to teach PSTs what reflection is and how to reflect on their practice. The findings also showed the need for small group facilitator-guided support in the development of PSTs’ reflective practice. , Thesis (PhD) -- Faculty of Education, Education, 2020
- Full Text:
- Authors: Chikiwa, Samukeliso
- Date: 2020-04-30
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/355357 , vital:64492
- Description: This study explored the development of reflective practice in foundation phase pre-service teachers in the context of video-based lesson analysis at a university in South Africa. The study was conducted in the field of mathematics education, responding to the urgent need to equip pre-service South African teachers with the knowledge and skills for effective mathematics teaching. The research is foregrounded by the continuing poor performance of South African learners in mathematics at all levels of education in the country, which has been linked to the inadequate knowledge and skills of mathematics teachers. Pre-service teacher education is putting considerable effort into improving the preparation of mathematics teachers and developing their ability to reflect on their teaching practice is one of the strategies being employed for this purpose. Research has demonstrated the importance of reflective practice (RP) in both developing and extending teachers’ mathematical knowledge for teaching. This study therefore contributes to current research that supports the development of RP as a professional skill for promoting the acquisition of knowledge for teaching in pre-service teacher education. The study adopted a qualitative case study approach with two phases of data collection. In Phase 1 I collected and analysed three sets of 19 pre-service teachers’ written reflections to establish the nature of the reflections that they developed when analysing video-recorded mathematics lessons of experienced teachers’ practice. Phase 2 was conducted with four PSTs who reflected on video-recorded mathematics lessons of their own practice, and similarly sought to investigate the nature of the reflections they developed when reflecting on practice. The four PSTs wrote one set of reflections on their own lessons, went through three sessions of facilitator-guided reflections, then wrote another set of reflections to establish if the support provided in small group facilitator-guided sessions improved their reflections. Iterative content analysis was employed to analyse the PSTs’ written reflections, using an analytic tool that I developed for this purpose through merging Lee’s (2007) and Muir and Beswick’s (2007) levels of reflection frameworks. My model had four levels of reflection: description, explanation, suggestion and reflectivity. The names of each of the levels connect to the key indicator for that level. PSTs’ written reflections were coded and analysed according to these levels. The study found that PSTs’ initial reflections were mostly description of general classroom events with little reflection at the levels of explanation and suggestion, and an absence of reflectivity. Most reflections focused on general events in the lesson rather than mathematical events, even though the six lens framework they were given to guide their reflections prompted them to steer their attention towards mathematical events. The second and third sets of reflections, although mostly still at level 1, showed some shifts towards explanation and suggestion, although an increased focus on mathematical events though reflectivity was still largely absent. No PST reached the fourth level of reflectivity in Phase 1. However, in Phase 2, the PSTs’ reflections after the three small group facilitator-guided sessions included some evidence of reflectivity. The findings suggest the need for pre-service teacher educators to make a concerted effort to teach PSTs what reflection is and how to reflect on their practice. The findings also showed the need for small group facilitator-guided support in the development of PSTs’ reflective practice. , Thesis (PhD) -- Faculty of Education, Education, 2020
- Full Text:
Repurposing a polymer precursor scaffold for medicinal application: Synthesis, characterization and biological evaluation of ferrocenyl 1,3-benzoxazine derivatives as potential antiprotozoal and anticancer agents
- Authors: Mbaba, Mziyanda
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164502 , vital:41124 , DOI 10.21504/10962/164502
- Description: The benzoxazines are a prominent class of heterocyclic compounds that possess a multitude of properties. To this end, benzoxazine derivatives have been used as versatile compounds for various utilities ranging from biological applications to the fabrication of polymers. Particularly, the 1,3-benzoxazine scaffold has featured in several bioactive compounds showing antimalarial, anticancer and antibacterial activities. Traditionally, it has been employed as a substrate in the synthesis of polymers with appealing physical and chemical properties. Due to the increasing interest in the polymer application of 1,3-benzoxazines, research of the 1,3-benzoxazine motif for polymer synthesis has been prioritized over other applications including its medicinal potential. The continuous development of resistance to clinical anticancer and antimalarial drugs has necessitated the need for the search of innovative bioactive compounds as potential alternative medicinal agents. To address this, the field of medicinal chemistry is adapting new approaches to counter resistance by incorporating nonconventional chemical moieties such as organometallic complexes, like ferrocene, into bioactive chemical motifs to serve as novel compounds with medicinal benefits. Incorporation of ferrocene into known bioactive chemical moieties has been shown to impart beneficial biological effects into the resultant compounds, which include the introduction of novel, and sometimes varied, mechanistic modalities and enhanced potency. Presented with the benefits of this strategy, the current work aims to design and evaluate the pharmaceutical capacity of novel derivatives containing 1,3-benzoxazine scaffold (traditionally applied in polymer synthesis) hybridized with the organometallic ferrocene unit as bioactive agents. Using a combination of expedient synthetic procedures such as the Burke three-component Mannich-type condensation, Vilsmeier-Haack formylation and reductive amination, four series of ferrocenyl 1,3-benzoxazine derivatives were synthesized and their structures confirmed by common spectroscopic techniques: nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). The target compounds were evaluated in vitro for potential antimalarial and anticancer activities against strains of the malaria parasite (Plasmodium falciparum 3D7 and Dd2) and the triple-negative breast cancer cell line HCC70. Compounds exhibited higher potency towards the Plasmodium falciparum strains with IC50 values in the low and sub-micromolar range in comparison to the breast cancer cell line against for which mid-molar activities were observed. To gain insight into the possible mode of action of ferrocenyl 1,3-benzoxazines, representative compounds showing most efficacy from each series were assessed for DNA binding affinity by employing UV-Vis and fluorescence DNA titration experiments. The selected compounds were found to interact with the DNA by binding to the minor groove, and these findings were confirmed by in silico ligand docking studies using a B-DNA structure as the receptor. Compound 3.16c (IC50: 0.261 μM [3D7], 0.599 μM [Dd2], 11.0 μM [HCC70]), which emerged as the most promising compound, was found to induce DNA damage in HCC70 cancer cells when investigated for effects of DNA interaction. Additionally, compound 3.16c displayed a higher binding constant (Kb) against DNA isolated from 3D7 Plasmodium falciparum trophozoites (Kb = 1.88×106 M-1) than the mammalian DNA (Kb = 6.33×104 M-1) from calf thymus, thus explaining the preferred selectivity of the compounds for the malaria parasite. Moreover, the investigated compounds demonstrated binding affinity for synthetic hemozoin, β-hematin. Collectively, these data suggest that the compounds possess a dual mode of action for antimalarial activity involving DNA interaction and hemozoin inhibition. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
- Authors: Mbaba, Mziyanda
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/164502 , vital:41124 , DOI 10.21504/10962/164502
- Description: The benzoxazines are a prominent class of heterocyclic compounds that possess a multitude of properties. To this end, benzoxazine derivatives have been used as versatile compounds for various utilities ranging from biological applications to the fabrication of polymers. Particularly, the 1,3-benzoxazine scaffold has featured in several bioactive compounds showing antimalarial, anticancer and antibacterial activities. Traditionally, it has been employed as a substrate in the synthesis of polymers with appealing physical and chemical properties. Due to the increasing interest in the polymer application of 1,3-benzoxazines, research of the 1,3-benzoxazine motif for polymer synthesis has been prioritized over other applications including its medicinal potential. The continuous development of resistance to clinical anticancer and antimalarial drugs has necessitated the need for the search of innovative bioactive compounds as potential alternative medicinal agents. To address this, the field of medicinal chemistry is adapting new approaches to counter resistance by incorporating nonconventional chemical moieties such as organometallic complexes, like ferrocene, into bioactive chemical motifs to serve as novel compounds with medicinal benefits. Incorporation of ferrocene into known bioactive chemical moieties has been shown to impart beneficial biological effects into the resultant compounds, which include the introduction of novel, and sometimes varied, mechanistic modalities and enhanced potency. Presented with the benefits of this strategy, the current work aims to design and evaluate the pharmaceutical capacity of novel derivatives containing 1,3-benzoxazine scaffold (traditionally applied in polymer synthesis) hybridized with the organometallic ferrocene unit as bioactive agents. Using a combination of expedient synthetic procedures such as the Burke three-component Mannich-type condensation, Vilsmeier-Haack formylation and reductive amination, four series of ferrocenyl 1,3-benzoxazine derivatives were synthesized and their structures confirmed by common spectroscopic techniques: nuclear magnetic resonance (NMR), infrared spectroscopy (IR) and high-resolution mass spectrometry (HRMS). The target compounds were evaluated in vitro for potential antimalarial and anticancer activities against strains of the malaria parasite (Plasmodium falciparum 3D7 and Dd2) and the triple-negative breast cancer cell line HCC70. Compounds exhibited higher potency towards the Plasmodium falciparum strains with IC50 values in the low and sub-micromolar range in comparison to the breast cancer cell line against for which mid-molar activities were observed. To gain insight into the possible mode of action of ferrocenyl 1,3-benzoxazines, representative compounds showing most efficacy from each series were assessed for DNA binding affinity by employing UV-Vis and fluorescence DNA titration experiments. The selected compounds were found to interact with the DNA by binding to the minor groove, and these findings were confirmed by in silico ligand docking studies using a B-DNA structure as the receptor. Compound 3.16c (IC50: 0.261 μM [3D7], 0.599 μM [Dd2], 11.0 μM [HCC70]), which emerged as the most promising compound, was found to induce DNA damage in HCC70 cancer cells when investigated for effects of DNA interaction. Additionally, compound 3.16c displayed a higher binding constant (Kb) against DNA isolated from 3D7 Plasmodium falciparum trophozoites (Kb = 1.88×106 M-1) than the mammalian DNA (Kb = 6.33×104 M-1) from calf thymus, thus explaining the preferred selectivity of the compounds for the malaria parasite. Moreover, the investigated compounds demonstrated binding affinity for synthetic hemozoin, β-hematin. Collectively, these data suggest that the compounds possess a dual mode of action for antimalarial activity involving DNA interaction and hemozoin inhibition. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
- Full Text:
The Role of HSP70/HSP90 Organizing Protein (Hop) in the Heat Shock Factor 1 (HSF1)-mediated Stress Response
- Authors: Chakraborty, Abantika
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/163204 , vital:41018 , doi:10.21504/10962/163204
- Description: Molecular chaperones regulate cellular proteostasis. They control protein conformation and prevent misfolding and aggregation under both normal and stressful environments, ultimately resulting in cell survival. The project aimed to understand the role of the HSP70 – HSP90 Organizing Protein (Hop/STIP1) in the survival of stressed cells and the function of the stress-responsive transcription factor, Heat Shock Factor 1 (HSF1). HSF1 protein levels were significantly reduced in Hop-depleted HEK293T cells compared to controls by ELISA, western blot, and mass spectrometry. HSF1 transcriptional activity at the HSP70 promoter, and binding of a biotinylated HSE oligonucleotide under basal conditions were significantly reduced, consistent with the reduced levels of HSF1. In response to heat shock, HSF1 levels in Hop-depleted cells increased to that of controls, but there was still significantly lowerHSF1 transcriptional activity and HSE binding. Hop-depleted HEK293T cells were more sensitive than controls to the HSF1 inhibitor KRIBB11 and showed reduced short-term and long-term proliferation. Unlike the HSP90 inhibitor 17-DMAG, which had no effect, the HSP70 inhibitor JG98, further decreased the levels of HSF1 in Hop-depleted cells, suggesting a role for HSP70 in the Hop-mediated effects. There was punctate nuclear staining for HSF1 in Hop-depleted cells under both basal and heat shock conditions, as well as reduced nuclear localization and increased cytoplasmic accumulation of HSF1 in response to heat shock. Hop and HSF1 colocalized in cells, and HSF1 could be isolated in complex with Hop and HSP70. Loss of Hop reduced HSF1 in HSP70complexes but did not affect HSF1 abundance in HSP90 complexes. Hop-depleted cells showed reduced short-term and long-term survival compared to controls, an effect that was potentiated by the JG98 HSP70 inhibitor. Taken together, these data suggest that Hop regulation of HSF1activity is via a mechanism involving reductions in HSP70 interaction, as well as reduced nuclear localization, and DNA binding, and is consistent with reduced cellular fitness under basal and stress conditions. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
- Authors: Chakraborty, Abantika
- Date: 2020
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/163204 , vital:41018 , doi:10.21504/10962/163204
- Description: Molecular chaperones regulate cellular proteostasis. They control protein conformation and prevent misfolding and aggregation under both normal and stressful environments, ultimately resulting in cell survival. The project aimed to understand the role of the HSP70 – HSP90 Organizing Protein (Hop/STIP1) in the survival of stressed cells and the function of the stress-responsive transcription factor, Heat Shock Factor 1 (HSF1). HSF1 protein levels were significantly reduced in Hop-depleted HEK293T cells compared to controls by ELISA, western blot, and mass spectrometry. HSF1 transcriptional activity at the HSP70 promoter, and binding of a biotinylated HSE oligonucleotide under basal conditions were significantly reduced, consistent with the reduced levels of HSF1. In response to heat shock, HSF1 levels in Hop-depleted cells increased to that of controls, but there was still significantly lowerHSF1 transcriptional activity and HSE binding. Hop-depleted HEK293T cells were more sensitive than controls to the HSF1 inhibitor KRIBB11 and showed reduced short-term and long-term proliferation. Unlike the HSP90 inhibitor 17-DMAG, which had no effect, the HSP70 inhibitor JG98, further decreased the levels of HSF1 in Hop-depleted cells, suggesting a role for HSP70 in the Hop-mediated effects. There was punctate nuclear staining for HSF1 in Hop-depleted cells under both basal and heat shock conditions, as well as reduced nuclear localization and increased cytoplasmic accumulation of HSF1 in response to heat shock. Hop and HSF1 colocalized in cells, and HSF1 could be isolated in complex with Hop and HSP70. Loss of Hop reduced HSF1 in HSP70complexes but did not affect HSF1 abundance in HSP90 complexes. Hop-depleted cells showed reduced short-term and long-term survival compared to controls, an effect that was potentiated by the JG98 HSP70 inhibitor. Taken together, these data suggest that Hop regulation of HSF1activity is via a mechanism involving reductions in HSP70 interaction, as well as reduced nuclear localization, and DNA binding, and is consistent with reduced cellular fitness under basal and stress conditions. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2020
- Full Text:
Outcome and impact assessment in the comprehensive evaluation of rural ICT projects in developing countries
- Mtkoko, Hafeni Tulimewawa Wilhelmina Lyatenda
- Authors: Mtkoko, Hafeni Tulimewawa Wilhelmina Lyatenda
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64483 , vital:28548 , DOI 10.21504/10962/64483
- Description: Despite existing literature that indicates that Information and communication technologies (ICTs) act as tools for social change and development, there is still limited empirical evidence that demonstrates this. An outcome and impact assessment based on a comprehensive (holistic) evaluation is deemed appropriate at a time when many ICT4D programmes fail to effectively demonstrate their impact towards rural development. A comprehensive evaluation is one that incorporates the evaluation of the need, design, implementation, outcome and impact, efficiency, and scalability of a programme. These stages make up the different domains of an evaluation lifecycle. The following study aims to develop an outcome and impact assessment framework for ICT4D programmes. It forms part of continuous research associated with the development of a rural ICT Comprehensive Evaluation framework. A theoretical approach, using Design Science and Weick’s theorizing process, was applied to investigate the development of a framework (design artefact) for outcome and impact assessment of ICT4D programmes. The theorizing process analysed existing outcome and impact assessment frameworks from social programmes, information systems/technology programmes, and ICT4D programmes. The output of the theorizing process proposes five critical themes of outcome and impact assessment of rural ICT4D programmes that should be assessed. These themes include: Strategic Value, Most Significant Change, Empowerment, Livelihoods, and Sustainability. To assess its utility, the framework was implemented in the Siyakhula Living Lab and Information and Communication Technology for Rural Education (ICT4RED) projects in South Africa. Through the application of the framework in real life ICT4D contexts, the lessons learned contributed to its revision and enhancement. The proposed framework aims to guide evaluators through the assessment of outcomes and impacts in ICT4D programmes. It provides a foundation and justification for the selected outcome and impact assessment themes that contribute to a comprehensive evaluation. An outcome and impact assessment that is informed by: baseline; needs assessment; programme theory assessment; and process assessment data, provides ICT4D evaluators and project stakeholders with meaningful outcome and impact feedback. Having such an approach to outcome and impact assessment ensures that the evaluation process is seen more holistically as part of the ICT4D project as a whole. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2017
- Full Text:
- Authors: Mtkoko, Hafeni Tulimewawa Wilhelmina Lyatenda
- Date: 2017
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/64483 , vital:28548 , DOI 10.21504/10962/64483
- Description: Despite existing literature that indicates that Information and communication technologies (ICTs) act as tools for social change and development, there is still limited empirical evidence that demonstrates this. An outcome and impact assessment based on a comprehensive (holistic) evaluation is deemed appropriate at a time when many ICT4D programmes fail to effectively demonstrate their impact towards rural development. A comprehensive evaluation is one that incorporates the evaluation of the need, design, implementation, outcome and impact, efficiency, and scalability of a programme. These stages make up the different domains of an evaluation lifecycle. The following study aims to develop an outcome and impact assessment framework for ICT4D programmes. It forms part of continuous research associated with the development of a rural ICT Comprehensive Evaluation framework. A theoretical approach, using Design Science and Weick’s theorizing process, was applied to investigate the development of a framework (design artefact) for outcome and impact assessment of ICT4D programmes. The theorizing process analysed existing outcome and impact assessment frameworks from social programmes, information systems/technology programmes, and ICT4D programmes. The output of the theorizing process proposes five critical themes of outcome and impact assessment of rural ICT4D programmes that should be assessed. These themes include: Strategic Value, Most Significant Change, Empowerment, Livelihoods, and Sustainability. To assess its utility, the framework was implemented in the Siyakhula Living Lab and Information and Communication Technology for Rural Education (ICT4RED) projects in South Africa. Through the application of the framework in real life ICT4D contexts, the lessons learned contributed to its revision and enhancement. The proposed framework aims to guide evaluators through the assessment of outcomes and impacts in ICT4D programmes. It provides a foundation and justification for the selected outcome and impact assessment themes that contribute to a comprehensive evaluation. An outcome and impact assessment that is informed by: baseline; needs assessment; programme theory assessment; and process assessment data, provides ICT4D evaluators and project stakeholders with meaningful outcome and impact feedback. Having such an approach to outcome and impact assessment ensures that the evaluation process is seen more holistically as part of the ICT4D project as a whole. , Thesis (PhD) -- Faculty of Commerce, Information Systems, 2017
- Full Text:
Behaviour and trophic ecology of oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) associated with floating objects in the open ocean
- Forget, Fabien Rocky Gilbert
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
- Authors: Forget, Fabien Rocky Gilbert
- Date: 2016
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193531 , vital:45340
- Description: The oceanic triggerfish (Canthidermis maculata) and rainbow runner (Elagatis bipinnulata) are epipelagic species that commonly associate with floating objects throughout the world’s tropical oceans. Besides tunas, these two species often form the bulk of the aggregation and are major non-target species (bycatch) incidentally captured at fish aggregation devices (FADs) by tropical tuna purse seiners. Despite being abundant, little is known about their basic biology, ecology and associative behavior with floating objects. This thesis aims to address knowledge gaps in their associative behavior and ecology at floating objects and attempts to explore potential bycatch mitigation methods. Acoustic telemetry was used to characterise several aspects of the two species’ behavior at floating objects. Fish were captured and tagged at drifting FADs in the core of the western Indian Ocean tuna fishing grounds. Prolonged remote observations were obtained through satellite linked receivers which provided fine-scale data on the behavior of oceanic triggerfish (n= 46 919 cumulated observation days) and rainbow runner (n= 24 538 cumulated observation days). The two species remained associated with the same floating object for periods extending up to several months. The mean residence time estimated using a survival analysis was 65 days for oceanic triggerfish and 94 days for rainbow runner. A distinct diel pattern in association was observed; the two species were closely associated to the FAD during the night and increased their home range during the day while performing short excursions (oceanic triggerfish mean: 2.0 hours ±1.6 SD; rainbow runner mean: 2.4 hours ±2.2 SD) away from the FAD. Similarly, distinct patterns in the vertical movements and locomotory activity (measured using accelerometer tags) were observed as the two species increased their vertical movements and activity levels during the day. Generally, their vertical movements were largely restricted to the mixed layer (< 60 m). At night, the two species remained close to the surface (0-5 m) where they appear to be in a resting state. An interesting behavioural switch in activity levels and vertical distribution was observed for oceanic triggerfish which coincided with a change in the environment as the FAD drifted close to a cold-core cyclonic eddy. Ambient light appears to be the key stimulus triggering the observed diel behavioural patterns. species-specific vulnerability for target species, skipjack (Katsuwonus pelamis), yellowfin (Thunnus albacares), bigeye tuna (Thunnus obesus) and non-target species, including silky shark (Carcharhinus falciformis), oceanic triggerfish, and rainbow runner, to the purse seine fishing gear were investigated. Hourly presence rates at FADs over 24 hours were examined to assess whether the capture rate of non-target species could be reduced at specific times during the day. Silky sharks displayed a similar associative pattern to that of targeted tunas. Moreover, the vulnerability of both target and non-target species were close to the maximum during the period of behavioural transitions at sunrise when the majority of the fishing sets are made. As such, a change in set time in the western Indian Ocean does not appear to be a feasible method to reduce capture rates of non-target species. Stomach content and stable isotope analysis were conducted on oceanic triggerfish (stomach n = 152, isotope n = 65) and rainbow runner (stomach n = 156, isotope n = 71) incidentally captured individuals at FADs by purse seiners. Typical FAD-associated prey items represented a minor component of their diet as they predominantly foraged on zooplankton and micronekton in the water column, suggesting that oceanic triggerfish and rainbow runner do not associate to floating objects for direct trophic advantages. Overlap in their dietary and isotopic niches indicates an intermediate level of competition. Overall, the spatial and trophic ecology of both species are remarkably similar and prolonged associations with FADs indicates that floating objects play a significant ecological role in the pelagic environment for the two species. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2016
- Full Text:
Modification and application of the decentralised wastewater treatment technology for greywater treatment to reduce water needs
- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2015
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193509 , vital:45338
- Description: Water is a scarce resource that is being acknowledged as a limiting factor to further social- economic growth and development. Demand for freshwater is increasing with corresponding increases in human population, industrial and agricultural activities. Alternative sources, such as greywater and rainwater are often polluted. Though greywater can be used for non-potable purposes, such as irrigation, it still requires some measures of treatment to improve its quality. To improve on greywater quality to facilitate its reuse, decentralised wastewater treatment technologies carry a great potential as complementary and alternative means of wastewater management particularly in peri-urban areas. Five research goals are addressed in this thesis: (i) to monitor the performance of Fly Ash Lime Filter Tower (FLFT) in the treatment of greywater; (ii) to modify the Fly Ash Lime Filter Tower in the treatment of greywater in order to reduce the pH of the greywater, and improved on the reduction of chemical oxygen demand (COD) and coliform counts; (iii) to investigate the potential of the reuse of greywater for irrigation; (iv) to undertake a techno analysis of the FLFT system for commercial use; and (v) to evaluate the use of hydrogen-sulphide (H2S) test kit to monitor faecal contamination of various water sources using a multidisciplinary approach. The modification of the FLFT indicated good treatment efficiency, reducing the concentrations of COD, chlorides, nitrates, ammonia and sulphate by 82.6%, 60.4%, 72.9%, 60.5%, and 53.9%, respectively; while the average pH was at 8.3. Greywater contains nutrients that are beneficial to the growth of most plants. Growth variables included biomass, stem height, number of leaves and number of vegetables harvested. Soil analysis showed no effects of the treated greywater on soil physico-chemical and microbial quality with bulk density 2.0g/cm3, average pH 7.4, total phosphorus 0.16mg/L 8, faecal coliform 0.3 CFU/100 ml. The tomatoes had high biomass and dry weight (150 g; 33g) than beetroot (35 g; 15 g). Crops irrigated with greywater significantly grew faster compared with those irrigated with tap water. The community approach highlighted the value of knowledge management in greywater reuse. It highlighted the importance of creating an institutional knowledge in water management using the H2S kit. The techno-economic analysis was used to evaluate key factors and the activities that are relevant to develop a sustainable FLFT in order to gain insights into the possibility of developing, and incorporating a business model framework to support decision making in value creation and value capturing during the research and the scaling up of the system. By this, a long term perspective to accomplish sustainable FLFT service businesses can be achieved. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2015
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- Authors: Ngqwala, Nosiphiwe Patience
- Date: 2015
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/193509 , vital:45338
- Description: Water is a scarce resource that is being acknowledged as a limiting factor to further social- economic growth and development. Demand for freshwater is increasing with corresponding increases in human population, industrial and agricultural activities. Alternative sources, such as greywater and rainwater are often polluted. Though greywater can be used for non-potable purposes, such as irrigation, it still requires some measures of treatment to improve its quality. To improve on greywater quality to facilitate its reuse, decentralised wastewater treatment technologies carry a great potential as complementary and alternative means of wastewater management particularly in peri-urban areas. Five research goals are addressed in this thesis: (i) to monitor the performance of Fly Ash Lime Filter Tower (FLFT) in the treatment of greywater; (ii) to modify the Fly Ash Lime Filter Tower in the treatment of greywater in order to reduce the pH of the greywater, and improved on the reduction of chemical oxygen demand (COD) and coliform counts; (iii) to investigate the potential of the reuse of greywater for irrigation; (iv) to undertake a techno analysis of the FLFT system for commercial use; and (v) to evaluate the use of hydrogen-sulphide (H2S) test kit to monitor faecal contamination of various water sources using a multidisciplinary approach. The modification of the FLFT indicated good treatment efficiency, reducing the concentrations of COD, chlorides, nitrates, ammonia and sulphate by 82.6%, 60.4%, 72.9%, 60.5%, and 53.9%, respectively; while the average pH was at 8.3. Greywater contains nutrients that are beneficial to the growth of most plants. Growth variables included biomass, stem height, number of leaves and number of vegetables harvested. Soil analysis showed no effects of the treated greywater on soil physico-chemical and microbial quality with bulk density 2.0g/cm3, average pH 7.4, total phosphorus 0.16mg/L 8, faecal coliform 0.3 CFU/100 ml. The tomatoes had high biomass and dry weight (150 g; 33g) than beetroot (35 g; 15 g). Crops irrigated with greywater significantly grew faster compared with those irrigated with tap water. The community approach highlighted the value of knowledge management in greywater reuse. It highlighted the importance of creating an institutional knowledge in water management using the H2S kit. The techno-economic analysis was used to evaluate key factors and the activities that are relevant to develop a sustainable FLFT in order to gain insights into the possibility of developing, and incorporating a business model framework to support decision making in value creation and value capturing during the research and the scaling up of the system. By this, a long term perspective to accomplish sustainable FLFT service businesses can be achieved. , Thesis (PhD) -- Faculty of Pharmacy, Pharmacy, 2015
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Reactor development and process optimisation for the bioremediation of phenolic wastewaters by trametes species
- Authors: Ryan, Daniel Reginald
- Date: 2004-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191487 , vital:45103
- Description: In many service industries, the source of a company’s value has shifted from capital to knowledge and ideas, the quality of which is dependent on its employees (Wooldridge, 2006). In fact, human resources can be considered part of factor conditions which can positively impact on a firm’s competitive context. This impact can ultimately translate into improved financial results (Porter and Kramer, 2002). There is therefore a growing interest in ways to attract and retain talent. According to the managers of many big companies, well communicated corporate responsibility practices can improve staff attraction as well as retention rates by improving morale (CSRwire, 2002). To explore this, a small, creative company in Johannesburg which engages in charity work was selected as a case study, with the goal being to understand whether their culture of good deeds has a positive impact on staff wellbeing. While the owner of the company actively attempts to make the company an enjoyable place to work at, he appears to have initiated the philanthropic activities in a true spirit of giving, rather than with the motive of engaging staff in order to make more money. Nevertheless, the researcher’s investigative stance is that of an enlightened egoist, and the study focuses on the business case of giving being beneficial to the giver (ultimately the company) in the long term, as well as to the recipient. While the danger of suggesting that philanthropy could be instrumentalised is acknowledged (Morton, 2004), the investigation explores the possibility because such evidence could persuade other companies to become more socially concerned. Through a qualitative approach involving interviews, observation and analysis of video footage, it becomes apparent that there is clearly value for the staff in the charity work they do. Unfortunately the multiple initiatives undertaken to keep staff morale high at the company make it impossible to establish a clear link between the philanthropy and overall wellbeing, but as the study was conducted in the phenomenological paradigm the main concern was with understanding the experience of participants. However, an unexpected finding was that the employees derive great satisfaction from using their professional skills for charity work rather than just donating money to the charity. They feel that their skills uniquely position them to make significant changes to the lives of others, which gives them a sense of pride and achievement that they don’t necessarily experience in their ordinary activities at work. On the basis of this, it is recommended that companies look to involve staff with projects that require their specific expertise when evaluating philanthropic initiatives. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2004
- Full Text:
- Authors: Ryan, Daniel Reginald
- Date: 2004-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191487 , vital:45103
- Description: In many service industries, the source of a company’s value has shifted from capital to knowledge and ideas, the quality of which is dependent on its employees (Wooldridge, 2006). In fact, human resources can be considered part of factor conditions which can positively impact on a firm’s competitive context. This impact can ultimately translate into improved financial results (Porter and Kramer, 2002). There is therefore a growing interest in ways to attract and retain talent. According to the managers of many big companies, well communicated corporate responsibility practices can improve staff attraction as well as retention rates by improving morale (CSRwire, 2002). To explore this, a small, creative company in Johannesburg which engages in charity work was selected as a case study, with the goal being to understand whether their culture of good deeds has a positive impact on staff wellbeing. While the owner of the company actively attempts to make the company an enjoyable place to work at, he appears to have initiated the philanthropic activities in a true spirit of giving, rather than with the motive of engaging staff in order to make more money. Nevertheless, the researcher’s investigative stance is that of an enlightened egoist, and the study focuses on the business case of giving being beneficial to the giver (ultimately the company) in the long term, as well as to the recipient. While the danger of suggesting that philanthropy could be instrumentalised is acknowledged (Morton, 2004), the investigation explores the possibility because such evidence could persuade other companies to become more socially concerned. Through a qualitative approach involving interviews, observation and analysis of video footage, it becomes apparent that there is clearly value for the staff in the charity work they do. Unfortunately the multiple initiatives undertaken to keep staff morale high at the company make it impossible to establish a clear link between the philanthropy and overall wellbeing, but as the study was conducted in the phenomenological paradigm the main concern was with understanding the experience of participants. However, an unexpected finding was that the employees derive great satisfaction from using their professional skills for charity work rather than just donating money to the charity. They feel that their skills uniquely position them to make significant changes to the lives of others, which gives them a sense of pride and achievement that they don’t necessarily experience in their ordinary activities at work. On the basis of this, it is recommended that companies look to involve staff with projects that require their specific expertise when evaluating philanthropic initiatives. , Thesis (PhD) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2004
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Applications of camphor-derived chiral auxiliaries in the asymmetric synthesis of α-amino acids and other systems
- Authors: Matjila, Joseph Moemise
- Date: 1998-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191501 , vital:45106
- Description: A viable synthetic route to camphor-derived imino lactones as precursors for the asymmetric synthesis of a-amino acids has been established. Several synthetic strategies have been investigated and the required regioisomeric imino lactones were finally obtained via the step-wise condensation of JV-(carbobenzyloxy)glycine with the a-ketols, 3-exo-hydroxycamphor and 2-exo- hydroxy-3-bomanone. Enolates of the camphor imino lactones, generated using potassium tert- butoxide, were reacted with a range of alkyl halides. Dialkylation was observed using the 2-imino lactone, while the regioisomeric 3-imino lactone derivative gave monoalkylated products with diastereoselectivities, shown by NMR spectroscopy, to range from 43% d.e. for the methylated product to > 99% d.e. for larger alkyl groups. The expected preference for endo-alkylation is supported by NMR (chemical shift, coupling constant and NOE) data and was confirmed by acidic hydrolysis of the pentylated 3-imino lactone to afford the known acid. Computer modelling, with the software package HYPERCHEM®, was used to explore the conformational properties of the alkylated products and their enolate precursors. Exploratory work on the enantiomeric beneficiation of racemic amino acids, using alkylated imino lactone derivatives, revealed preferential exo-protonation of the enolate intermediates. Asymmetric Baylis-Hillman reactions between a novel camphor-derived acrylic ester and a range of aldehydes afforded the corresponding 2-(hydroxyalkyl)acrylates in up to 59% d.e., the observed stereoselectivities being sensitive to both steric and electronic factors. Attempts to prepare imino lactone derivatives from ketopinic acid, although unsuccessful, led to the isolation of two novel W-(carbobenzyloxy)glycinates, whose structures were established by 1- and 2-D NMR spectroscopy. Attempts to prepare "BINAP" analogues from dibomyl ether's also proved unsuccessful, but the investigation led to the discovery of a third, novel dibomyl ether. , Thesis (PhD) -- Faculty of Science, Chemistry, 1998
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- Authors: Matjila, Joseph Moemise
- Date: 1998-04
- Subjects: Uncatalogued
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/191501 , vital:45106
- Description: A viable synthetic route to camphor-derived imino lactones as precursors for the asymmetric synthesis of a-amino acids has been established. Several synthetic strategies have been investigated and the required regioisomeric imino lactones were finally obtained via the step-wise condensation of JV-(carbobenzyloxy)glycine with the a-ketols, 3-exo-hydroxycamphor and 2-exo- hydroxy-3-bomanone. Enolates of the camphor imino lactones, generated using potassium tert- butoxide, were reacted with a range of alkyl halides. Dialkylation was observed using the 2-imino lactone, while the regioisomeric 3-imino lactone derivative gave monoalkylated products with diastereoselectivities, shown by NMR spectroscopy, to range from 43% d.e. for the methylated product to > 99% d.e. for larger alkyl groups. The expected preference for endo-alkylation is supported by NMR (chemical shift, coupling constant and NOE) data and was confirmed by acidic hydrolysis of the pentylated 3-imino lactone to afford the known acid. Computer modelling, with the software package HYPERCHEM®, was used to explore the conformational properties of the alkylated products and their enolate precursors. Exploratory work on the enantiomeric beneficiation of racemic amino acids, using alkylated imino lactone derivatives, revealed preferential exo-protonation of the enolate intermediates. Asymmetric Baylis-Hillman reactions between a novel camphor-derived acrylic ester and a range of aldehydes afforded the corresponding 2-(hydroxyalkyl)acrylates in up to 59% d.e., the observed stereoselectivities being sensitive to both steric and electronic factors. Attempts to prepare imino lactone derivatives from ketopinic acid, although unsuccessful, led to the isolation of two novel W-(carbobenzyloxy)glycinates, whose structures were established by 1- and 2-D NMR spectroscopy. Attempts to prepare "BINAP" analogues from dibomyl ether's also proved unsuccessful, but the investigation led to the discovery of a third, novel dibomyl ether. , Thesis (PhD) -- Faculty of Science, Chemistry, 1998
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