Photosynthetic and growth response of C₃ and C₄ subspecies of Alloteropsis semialata to nitrogen-supply
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008
- Authors: Abraham, Trevor Ian
- Date: 2008
- Subjects: Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4182 , http://hdl.handle.net/10962/d1003750 , Photosynthesis , Plants -- Effect of nitrogen on , Growth (Plants) , Plant ecology
- Description: The greater photosynthetic nitrogen use efficiency (PNUE) of C4 compared with C3 plants may explain the relative success of C4 grasses in nutrient poor environments. This study compared the responses in photosynthetic parameters, leaf nitrogen and biomass allocation between the C3 and C4 subspecies of Alloteropsis semialata supplied soil nitrogen at three levels. Photosynthesis was assessed by means of CO2 response curves and the leaf nitrogen content assayed. Plants were destructively harvested, leaf areas determined and the dry biomass of functional plant components was measured. Results confirmed that the higher PNUE of C4 plants allowed them to accumulate more biomass than C3 plants at the high nitrogen level, despite smaller leaf areas. The greater productivity of C4 plants enabled them to invest more in storage and sexual reproduction than in leaves when compared to the C3 plants. In contrast the C3 plants invested biomass in less efficient and more nitrogen demanding leaves and bigger root systems. PNUE and photosynthetic rates were not significantly affected by nitrogen-limitation in either subspecies and the major response was a decrease in biomass accumulation and an increase in biomass allocation to roots. This altered root to shoot ratio was accompanied by a lowered allocation to sexual reproduction in the C4 subspecies, but an unaltered allocation to leaves, while in the C3 subspecies there was a decrease in leaf allocation. In a further experiment, the C4 subspecies was supplied three levels of nitrogen provided as nitrate, or alternatively as ammonium plus nitrate, and leaves were excised to within 5 cm of the ground at the start of treatment. Prior to flowering, photosynthesis was assessed by means of CO2 response curves and the plants were destructively harvested. Leaf areas and the dry biomass of functional plant components were determined, and at levels of nitrogen supply higher than those found in savanna soils the rate of photosynthesis was increased. Leaf re-growth was reduced by severe nitrogen limitation and co-provision of nitrate and ammonium had no significant effect other than increased tillering. Both subspecies of Alloteropsis semialata are adapted to nutrient poor environments and maintain photosynthetic rates by reducing leaf area. The C4 subspecies is likely to show greater resilience in disturbance-prone environments by exploiting its higher PNUE to allocate greater resources to storage and sexual reproduction, while the C3 subspecies is usually found in environments with closed canopies which favour vegetative growth, and allocate greater resources to leaves and roots.
- Full Text:
- Date Issued: 2008
Isolation and characterization of antiplasmodial metabolites from South African marine alga
- Authors: Afolayan, Anthonia Folake
- Date: 2008
- Subjects: Malaria -- Africa Antimalarials -- Therapeutic use Malaria -- Prevention Malaria -- Drug therapy Marine algae -- Therapeutic use Natural products -- Therapeutic use Plasmodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3739 , http://hdl.handle.net/10962/d1003063
- Description: Malaria is one of the three most deadly diseases in Africa. Although there are available treatments, their efficacy has been greatly reduced over the past two decades due to the development of resistance to currently available drugs. This has necessitated the search for new and effective antimalarial agents. This project approached the search for new antimalarial compounds in two ways: (i) by screening natural products isolated from marine algae against the Plasmodium parasite and (ii) by modification of selected isolated active compounds to target 1-deoxY-đ-xylulose 5-phosphate reductoisomerase (DXR), an enzyme found in the nonmevalonate isoprenoid biosynthetic pathway of Plasmodium Jalciparum. It was envisaged that such a compound would exhibit dual action on the Plasmodium parasite. Extracts obtained from 22 marine algae were prefractionated by solvent partitioning and were screened for anti plasmodial activity against the chloroquine sensitive (CQS) P. Jalciparum D 10 strain. Overall, 50% of the algae screened produced at least one crude fraction with activity against P. Jalciparum. Extracts of the algae Sargassum heterophyllum, Plocamium cornutum, Amphiroa ephedrea and Pterosiphonia cloiophylla gave the most promising results. Fractionation of S. heterophyllum afforded three tetraprenyltoluquinols (3.1, 3.2 and 3.5) and an all-trans-fucoxanthin (3.6). Three new compounds (4.5, 4.6 and 4.7) and two known halogenated monoterpenes (4.1 and 4.4) were isolated from P. cornutum. Each of the isolated compounds from both S. heterophyllum and P. cornutum showed antiplasmodial activity with IC₅₀ values ranging from 2.0 - 15.3 μM for S. heterophyllum and 13 - 230 μM for P. cornutum. Attempts to synthetically modify halogenated monoterpene 4.4 by dihydroxylation and phosphorylation in order to inhibit the DXR enzyme was unsuccessful. However, the hemiterpene analogue (5.42) of the halogenated monoterpenes was successfully phosphorylated and dihydroxylated to give compound 5.45 which showed promising activity against DXR. The result obtained indicated that the proposed phosphorylation and dihydroxylation of the halogenated monoterpene 4.4 would result in the synthesis of a potent DXR inhibitor and therefore a potential antimalarial agent with dual mode of action on the Plasmodium parasite.
- Full Text:
- Date Issued: 2008
- Authors: Afolayan, Anthonia Folake
- Date: 2008
- Subjects: Malaria -- Africa Antimalarials -- Therapeutic use Malaria -- Prevention Malaria -- Drug therapy Marine algae -- Therapeutic use Natural products -- Therapeutic use Plasmodium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3739 , http://hdl.handle.net/10962/d1003063
- Description: Malaria is one of the three most deadly diseases in Africa. Although there are available treatments, their efficacy has been greatly reduced over the past two decades due to the development of resistance to currently available drugs. This has necessitated the search for new and effective antimalarial agents. This project approached the search for new antimalarial compounds in two ways: (i) by screening natural products isolated from marine algae against the Plasmodium parasite and (ii) by modification of selected isolated active compounds to target 1-deoxY-đ-xylulose 5-phosphate reductoisomerase (DXR), an enzyme found in the nonmevalonate isoprenoid biosynthetic pathway of Plasmodium Jalciparum. It was envisaged that such a compound would exhibit dual action on the Plasmodium parasite. Extracts obtained from 22 marine algae were prefractionated by solvent partitioning and were screened for anti plasmodial activity against the chloroquine sensitive (CQS) P. Jalciparum D 10 strain. Overall, 50% of the algae screened produced at least one crude fraction with activity against P. Jalciparum. Extracts of the algae Sargassum heterophyllum, Plocamium cornutum, Amphiroa ephedrea and Pterosiphonia cloiophylla gave the most promising results. Fractionation of S. heterophyllum afforded three tetraprenyltoluquinols (3.1, 3.2 and 3.5) and an all-trans-fucoxanthin (3.6). Three new compounds (4.5, 4.6 and 4.7) and two known halogenated monoterpenes (4.1 and 4.4) were isolated from P. cornutum. Each of the isolated compounds from both S. heterophyllum and P. cornutum showed antiplasmodial activity with IC₅₀ values ranging from 2.0 - 15.3 μM for S. heterophyllum and 13 - 230 μM for P. cornutum. Attempts to synthetically modify halogenated monoterpene 4.4 by dihydroxylation and phosphorylation in order to inhibit the DXR enzyme was unsuccessful. However, the hemiterpene analogue (5.42) of the halogenated monoterpenes was successfully phosphorylated and dihydroxylated to give compound 5.45 which showed promising activity against DXR. The result obtained indicated that the proposed phosphorylation and dihydroxylation of the halogenated monoterpene 4.4 would result in the synthesis of a potent DXR inhibitor and therefore a potential antimalarial agent with dual mode of action on the Plasmodium parasite.
- Full Text:
- Date Issued: 2008
Cluster centre principals' perceptions of the implementation of the school cluster system in Namibia
- Authors: Aipinge, Lydia P
- Date: 2008
- Subjects: School management and organization -- Namibia Education -- Namibia School principals -- Namibia Educational leadership -- Namibia Educational change -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1449 , http://hdl.handle.net/10962/d1003330
- Description: The School Clustering System (SCS) was introduced five years after Namibia’s independence in 1990. The rationale for its implementation was to improve the quality of education in Namibian schools by enabling the sharing of resources, experience and expertise among clusters and facilitating school administration by pooling resources from several schools to be shared equally. It was piloted in Rundu and then gradually expanded to the whole country. The cluster system groups 5-7 schools that are eographically close and accessible to each other in one cluster under the leadership of one of the principals known as a Cluster Centre Principal (CCP). The purpose of this study was to investigate the perceptions of CCPs of the implementation of the SCS in two clusters of a particular circuit in the Omusati region. It is a case study involving two CCPs, one serving Inspector of Education (IE), a former Inspector of Education, several teachers, principals and parents. Data were collected through interviews, document analysis, and focus group discussions. The study found that the practice of cluster leaders is informed by contemporary leadership and management thinking. The participatory approach employed in clusterbased committees enables site-based management and collaboration. This has led to organisational learning. It was also found that a number of challenges are hampering the implementation of the SCS. These include lack of system support and inadequate resources. However, the human potential coupled with a high degree of readiness exhibited by cluster members are seen as potential drivers of further development of the system. The study recommends the adoption of a national policy that formalises the SCS as well as the strengthening of system support to build cluster capacity. It also makes suggestions for further research in organisational culture and behaviour with the aim of developing leadership and management practices in the SCS.
- Full Text:
- Date Issued: 2008
Cluster centre principals' perceptions of the implementation of the school cluster system in Namibia
- Authors: Aipinge, Lydia P
- Date: 2008
- Subjects: School management and organization -- Namibia Education -- Namibia School principals -- Namibia Educational leadership -- Namibia Educational change -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1449 , http://hdl.handle.net/10962/d1003330
- Description: The School Clustering System (SCS) was introduced five years after Namibia’s independence in 1990. The rationale for its implementation was to improve the quality of education in Namibian schools by enabling the sharing of resources, experience and expertise among clusters and facilitating school administration by pooling resources from several schools to be shared equally. It was piloted in Rundu and then gradually expanded to the whole country. The cluster system groups 5-7 schools that are eographically close and accessible to each other in one cluster under the leadership of one of the principals known as a Cluster Centre Principal (CCP). The purpose of this study was to investigate the perceptions of CCPs of the implementation of the SCS in two clusters of a particular circuit in the Omusati region. It is a case study involving two CCPs, one serving Inspector of Education (IE), a former Inspector of Education, several teachers, principals and parents. Data were collected through interviews, document analysis, and focus group discussions. The study found that the practice of cluster leaders is informed by contemporary leadership and management thinking. The participatory approach employed in clusterbased committees enables site-based management and collaboration. This has led to organisational learning. It was also found that a number of challenges are hampering the implementation of the SCS. These include lack of system support and inadequate resources. However, the human potential coupled with a high degree of readiness exhibited by cluster members are seen as potential drivers of further development of the system. The study recommends the adoption of a national policy that formalises the SCS as well as the strengthening of system support to build cluster capacity. It also makes suggestions for further research in organisational culture and behaviour with the aim of developing leadership and management practices in the SCS.
- Full Text:
- Date Issued: 2008
Ecological role of free-living bacteria in the microbial food web of the temporarily open/closed East Kleinemonde Estuary, South Africa
- Authors: Allan, Elizabeth Louise
- Date: 2008
- Subjects: Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5666 , http://hdl.handle.net/10962/d1005351 , Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Description: The main aim of this study was to assess the “top-down” and “bottom-up” control of bacterial production in the small temporarily open/closed East Kleinemonde Estuary, situated on the south-eastern coastline of southern Africa. Spatial and temporal patterns in bacterial abundance, biomass and production and the importance of abiotic and biotic factors were investigated over the period May 2006 to April 2007. The trophic interactions between bacteria, phytoplankton, nanoflagellates (< 20 μm), microzooplankton (< 200 μm) and mesozooplankton (< 2 000 μm) were investigated during winter and summer. Bacterial abundance, biomass and production ranged between 1.00 × 10⁹ and 4.93 × 10⁹ cells 1⁻¹, 32.4 and 109 μg C 1⁻¹ and 0.01 and 1.99 μg C 1⁻¹ h⁻¹, respectively. With a few exceptions there were no spatial patterns in the values. Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Nanoflagellate and bacterial abundances were significantly correlated to one another (lower reaches: r = 0.818, p < 0.001; middle reaches: r = 0.628, p < 0.001; upper reaches: r = 0.484, p < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the mean number of virus particles within each bacterial cell during this study demonstrated no temporal or spatial patterns and ranged from 0.5 to 6.1 % and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% of the total which suggests that viral lysis represented a very important source of bacterial mortality during this study. The biological interactions between the selected components of the plankton community demonstrated that among the heterotrophic components of the plankton, the nanoflagellates were identified as the most important consumers of bacteria and small phytoplankton cells (< 20 μm). In the presence of microzooplankton the impact of the nanoflagellates on both the bacteria and phytoplankton was reduced, indicating that larger heterotrophs were preying upon the nanoflagellates. Mesozooplankton, however, appeared to exert the greatest impact on nanoflagellates. In the cascading experiments, the data suggest that mesozooplankton consume nanoflagellates, which resulted in a decrease in the predation impact of these organisms on the bacteria. This result is consistent with predator-prey cascades. The presence of the larger heterotrophs therefore, mediates the interactions between the primary bacterivores, the nanoflagellates, and the bacteria within the temporarily open/closed East Kleinemonde Estuary.
- Full Text:
- Date Issued: 2008
- Authors: Allan, Elizabeth Louise
- Date: 2008
- Subjects: Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5666 , http://hdl.handle.net/10962/d1005351 , Bacterial growth -- South Africa -- Eastern Cape , Estuarine ecology -- South Africa -- Eastern Cape , Estuaries -- South Africa -- Eastern Cape , Microbial ecology -- South Africa -- Eastern Cape , Nutrient cycles -- South Africa -- Eastern Cape , Food chains (Ecology)
- Description: The main aim of this study was to assess the “top-down” and “bottom-up” control of bacterial production in the small temporarily open/closed East Kleinemonde Estuary, situated on the south-eastern coastline of southern Africa. Spatial and temporal patterns in bacterial abundance, biomass and production and the importance of abiotic and biotic factors were investigated over the period May 2006 to April 2007. The trophic interactions between bacteria, phytoplankton, nanoflagellates (< 20 μm), microzooplankton (< 200 μm) and mesozooplankton (< 2 000 μm) were investigated during winter and summer. Bacterial abundance, biomass and production ranged between 1.00 × 10⁹ and 4.93 × 10⁹ cells 1⁻¹, 32.4 and 109 μg C 1⁻¹ and 0.01 and 1.99 μg C 1⁻¹ h⁻¹, respectively. With a few exceptions there were no spatial patterns in the values. Bacterial abundance, biomass and production, however, demonstrated a distinct temporal pattern with the lowest values consistently recorded during the winter months. Nanoflagellate and bacterial abundances were significantly correlated to one another (lower reaches: r = 0.818, p < 0.001; middle reaches: r = 0.628, p < 0.001; upper reaches: r = 0.484, p < 0.05) suggesting a strong predator-prey relationship. The frequency of visibly infected bacterial cells and the mean number of virus particles within each bacterial cell during this study demonstrated no temporal or spatial patterns and ranged from 0.5 to 6.1 % and 12.0 to 37.5 virus particles per bacterium, respectively. Viral infection and lysis was thus a constant source of bacterial mortality throughout the year. The estimated percentage of bacterial production removed by viral lysis ranged between 7.8 and 88.9% of the total which suggests that viral lysis represented a very important source of bacterial mortality during this study. The biological interactions between the selected components of the plankton community demonstrated that among the heterotrophic components of the plankton, the nanoflagellates were identified as the most important consumers of bacteria and small phytoplankton cells (< 20 μm). In the presence of microzooplankton the impact of the nanoflagellates on both the bacteria and phytoplankton was reduced, indicating that larger heterotrophs were preying upon the nanoflagellates. Mesozooplankton, however, appeared to exert the greatest impact on nanoflagellates. In the cascading experiments, the data suggest that mesozooplankton consume nanoflagellates, which resulted in a decrease in the predation impact of these organisms on the bacteria. This result is consistent with predator-prey cascades. The presence of the larger heterotrophs therefore, mediates the interactions between the primary bacterivores, the nanoflagellates, and the bacteria within the temporarily open/closed East Kleinemonde Estuary.
- Full Text:
- Date Issued: 2008
An investigation of the implementation of the thematic approach in Namibian lower primary classrooms: a case study
- Authors: Amukushu-Niipare, Alina
- Date: 2008
- Subjects: Education, Elementary -- Namibia -- Case studies Teaching -- Namibia -- Case studies Education -- Namibia -- Case studies Educational change -- Namibia -- Case studies School integration -- Namibia -- Case studies Curriculum planning -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1651 , http://hdl.handle.net/10962/d1003534
- Description: This study focuses on the implementation of a thematic approach in the Namibian Lower Primary Phase of schooling. The purpose of the study is to investigate teachers’ perceptions and understanding of the thematic approach and also to explore how teachers plan and implement a thematic approach in their classrooms. It is argued that a thematic approach allows for a combination of subjects that integrate content across the curriculum in such a way that learners can see the relations among concepts and so build up their knowledge in a more meaningful way. The work was done in a qualitative paradigm using a case study approach. Findings reveal that the majority of teachers have a shallow conceptual understanding of the principles of a thematic approach and this causes difficulties in their practice. The investigation concludes that in order for teachers to deepen their conceptual understanding of the thematic approach, follow-up workshops are necessary to help them develop appropriate strategies for their classrooms.
- Full Text:
- Date Issued: 2008
- Authors: Amukushu-Niipare, Alina
- Date: 2008
- Subjects: Education, Elementary -- Namibia -- Case studies Teaching -- Namibia -- Case studies Education -- Namibia -- Case studies Educational change -- Namibia -- Case studies School integration -- Namibia -- Case studies Curriculum planning -- Namibia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1651 , http://hdl.handle.net/10962/d1003534
- Description: This study focuses on the implementation of a thematic approach in the Namibian Lower Primary Phase of schooling. The purpose of the study is to investigate teachers’ perceptions and understanding of the thematic approach and also to explore how teachers plan and implement a thematic approach in their classrooms. It is argued that a thematic approach allows for a combination of subjects that integrate content across the curriculum in such a way that learners can see the relations among concepts and so build up their knowledge in a more meaningful way. The work was done in a qualitative paradigm using a case study approach. Findings reveal that the majority of teachers have a shallow conceptual understanding of the principles of a thematic approach and this causes difficulties in their practice. The investigation concludes that in order for teachers to deepen their conceptual understanding of the thematic approach, follow-up workshops are necessary to help them develop appropriate strategies for their classrooms.
- Full Text:
- Date Issued: 2008
Normative indications for Xhosa-speaking unskilled workers on the trail making test and the stroop test
- Authors: Andrews, Karen Anne Hope
- Date: 2008
- Subjects: Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2926 , http://hdl.handle.net/10962/d1002435 , Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Description: The aim of the study was to produce preliminary normative indications for the Trail Making Test and the Stroop Test, administered in English, on a non-clinical sample of black, Xhosa-speaking, unskilled individuals (N = 33), with an educational level of 11 – 12 years, in two age categories (18 –29 and 30 – 40 years). The sample was equally distributed for gender and level of education. Participants, who were required to have a basic proficiency in English, were from traditionally black township schools with relatively disadvantaged quality of education. Within-sample age and gender effects were investigated. There were no significant age effects on the Trail Making Test, whereas there was one significant difference between age groups on the Stroop Test with respect to the Color-Word task, and a result that strongly approached significance on the Word task, with the younger group performing better than the older group. There were no significant gender effects on the Trail Making Test, whereas there was one significant difference between genders on the Stroop Test with respect to the Word task, and a result that approached significance on the Color task, with females performing better than males. Normative indications for both measures were compared to available normative data on western populations with higher levels and more advantaged quality of education. This comparison revealed consistently poorer performances for both the Trail Making Test and the Stroop Test, confirming the need for localised normative datasets to facilitate accurate neuropsychological diagnoses on culturally disadvantaged individuals.
- Full Text:
- Date Issued: 2008
- Authors: Andrews, Karen Anne Hope
- Date: 2008
- Subjects: Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:2926 , http://hdl.handle.net/10962/d1002435 , Neuropsychology , Neuropsychological tests -- Sex differences , Educational tests and measurements -- Sex differences , Xhosa (African people) -- Education
- Description: The aim of the study was to produce preliminary normative indications for the Trail Making Test and the Stroop Test, administered in English, on a non-clinical sample of black, Xhosa-speaking, unskilled individuals (N = 33), with an educational level of 11 – 12 years, in two age categories (18 –29 and 30 – 40 years). The sample was equally distributed for gender and level of education. Participants, who were required to have a basic proficiency in English, were from traditionally black township schools with relatively disadvantaged quality of education. Within-sample age and gender effects were investigated. There were no significant age effects on the Trail Making Test, whereas there was one significant difference between age groups on the Stroop Test with respect to the Color-Word task, and a result that strongly approached significance on the Word task, with the younger group performing better than the older group. There were no significant gender effects on the Trail Making Test, whereas there was one significant difference between genders on the Stroop Test with respect to the Word task, and a result that approached significance on the Color task, with females performing better than males. Normative indications for both measures were compared to available normative data on western populations with higher levels and more advantaged quality of education. This comparison revealed consistently poorer performances for both the Trail Making Test and the Stroop Test, confirming the need for localised normative datasets to facilitate accurate neuropsychological diagnoses on culturally disadvantaged individuals.
- Full Text:
- Date Issued: 2008
The attitudes of isiXhosa-speaking students toward various languages of learning and teaching (LOLT) issues at Rhodes University
- Authors: Aziakpono, Philomina
- Date: 2008
- Subjects: Rhodes University -- Students -- Attitudes Language and education -- South Africa Xhosa language -- Study and teaching (Higher) -- South Africa English language -- Study and teaching (Higher) -- South Africa Education, Bilingual -- South Africa Language policy -- South Africa Language planning -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2339 , http://hdl.handle.net/10962/d1002621
- Description: This study aims at eliciting opinions and beliefs of isiXhosa-speaking students to revealtheir attitudes toward various languages of learning and teaching (LOLT) issues at RhodesUniversity, and to determine the influence of a number of variables (such as age, gender,schooling background, level of study and field of study) on these attitudes. Another aim of the study is to compare the findings of this research to the recent findings on isiXhosaspeaking students’ language attitudes at the University of the Western Cape (Dyers 1999) and the University of Fort Hare (Dalvit 2004). Qualitative and quantitative methods were used: data was gathered using a survey that employed a questionnaire and interviews (individual and focus group). The questionnaire data is analysed through using percentage scores as well as mean values coupled with Chi-square tests, while the interviews are analysed qualitatively to further confirm the results of the quantitative analysis. Results are also compared with other recent surveys at South African universities. The results reveal that respondents had a generally positive attitude toward English as LOLT, based mainly on instrumental motivations. More importantly, there was a positive attitude toward the use of isiXhosa alongside English. The motivations for the use of isiXhosa were both instrumental and integrative in nature. The majority of respondents who supported a bilingual arrangement did not, however, believe that a fully-fledged bilingual policy would be practical, mainly because of the multilingual nature of Rhodes University. They felt, however, that providing English and isiXhosa exam question-papers, bilingual tutor support and isiXhosa definitions of discipline-specific technical terms would facilitate learning. Most of the variables mentioned above had an influence on the relevant language attitudes, often confirming the findings of other studies. For instance, schooling background greatly influenced the language attitudes of respondents. Those from previously advantaged English-only schools showed very positive attitudes toward an English-only policy, while most respondents from formerly disadvantaged DET bilingual schools were favourably disposed toward a bilingual policy of English and isiXhosa at Rhodes University. A comparison of the findings of this study with those of recent findings on isiXhosa students’ language attitudes at other universities reveals that respondents at the University of Fort Hare were most favourable toward a bilingual policy, those at the University of the Western Cape were to some extent favourable toward a bilingual arrangement, while respondents at Rhodes University were least favourable toward a bilingual policy.
- Full Text:
- Date Issued: 2008
- Authors: Aziakpono, Philomina
- Date: 2008
- Subjects: Rhodes University -- Students -- Attitudes Language and education -- South Africa Xhosa language -- Study and teaching (Higher) -- South Africa English language -- Study and teaching (Higher) -- South Africa Education, Bilingual -- South Africa Language policy -- South Africa Language planning -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2339 , http://hdl.handle.net/10962/d1002621
- Description: This study aims at eliciting opinions and beliefs of isiXhosa-speaking students to revealtheir attitudes toward various languages of learning and teaching (LOLT) issues at RhodesUniversity, and to determine the influence of a number of variables (such as age, gender,schooling background, level of study and field of study) on these attitudes. Another aim of the study is to compare the findings of this research to the recent findings on isiXhosaspeaking students’ language attitudes at the University of the Western Cape (Dyers 1999) and the University of Fort Hare (Dalvit 2004). Qualitative and quantitative methods were used: data was gathered using a survey that employed a questionnaire and interviews (individual and focus group). The questionnaire data is analysed through using percentage scores as well as mean values coupled with Chi-square tests, while the interviews are analysed qualitatively to further confirm the results of the quantitative analysis. Results are also compared with other recent surveys at South African universities. The results reveal that respondents had a generally positive attitude toward English as LOLT, based mainly on instrumental motivations. More importantly, there was a positive attitude toward the use of isiXhosa alongside English. The motivations for the use of isiXhosa were both instrumental and integrative in nature. The majority of respondents who supported a bilingual arrangement did not, however, believe that a fully-fledged bilingual policy would be practical, mainly because of the multilingual nature of Rhodes University. They felt, however, that providing English and isiXhosa exam question-papers, bilingual tutor support and isiXhosa definitions of discipline-specific technical terms would facilitate learning. Most of the variables mentioned above had an influence on the relevant language attitudes, often confirming the findings of other studies. For instance, schooling background greatly influenced the language attitudes of respondents. Those from previously advantaged English-only schools showed very positive attitudes toward an English-only policy, while most respondents from formerly disadvantaged DET bilingual schools were favourably disposed toward a bilingual policy of English and isiXhosa at Rhodes University. A comparison of the findings of this study with those of recent findings on isiXhosa students’ language attitudes at other universities reveals that respondents at the University of Fort Hare were most favourable toward a bilingual policy, those at the University of the Western Cape were to some extent favourable toward a bilingual arrangement, while respondents at Rhodes University were least favourable toward a bilingual policy.
- Full Text:
- Date Issued: 2008
The male novelist and the 'woman question' George Meredith's presentation of his Heroines in The Egoist (1879) and Diana of the Crossways (1885)
- Authors: Bell, Alan Nigel
- Date: 2008
- Subjects: Meredith, George, 1828-1909 -- Criticism and interpretation Meredith, George, 1828-1909. Egoist Meredith, George, 1828-1909. Diana of the Crossways English fiction -- 19th century -- History and criticism English fiction -- Male authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2203 , http://hdl.handle.net/10962/d1002245
- Description: Focusing on four early works, then three from his middle period and three from the 1890s, this dissertation explores Meredith’s role as a novelist in the unfolding of a social and literary paradox, namely, that with the death of George Eliot in 1880, the dominant writers of fiction were male, and this remained the case until the advent of Virginia Woolf, while at the same time the woman’s movement for emancipation in all spheres of life—domestic, commercial, professional and political—was gathering in strength and conviction. None of the late nineteenth-century male novelists—James, Hardy, Moore and Gissing, as well as Meredith—was ideologically committed to the feminist cause; in fact the very term ‘feminist’ did not begin to become current in England until the mid-1890s. But they were all interested in one aspect or another of the ‘Woman Question’, even if James was ambivalent about female emancipation, and Gissing, on the whole, was somewhat hostile. Of all these novelists, it was Meredith whose work, especially in its last two decades, most copiously reveals a profound sympathy for women and their struggles to realize their desires and ambitions, both inside and outside the home, in a patriarchal world. The dissertation therefore concentrates on his presentation of his heroines in their relationships with the men who, in one way or another, dominate them, and with whom they must negotiate, within the social and sexual conventions of the time, a modus vivendi—a procedure that will entail, especially in the later work, some transgression of those conventions. Chapter 1 sketches more than two centuries of development in female consciousness of severe social disadvantage, from literary observations in the mid-seventeenth century to the intensifying of political representations in the writings of Mary Wollstonecraft, and the rise of the woman’s movement in the course of the Victorian century. The chapter includes an account of the impact on Meredith of John Stuart Mill’s The Subjection of Women (1869), and an examination of some of his female friendships by way of illuminating the experiential component of his insights into the ‘Woman Question’ as reflected in his fiction and letters. His unhappy first marriage is reserved for consideration in Chapter 2, as background to the discussion of The Ordeal of Richard Feverel (1859). This early novel, Meredith’s first in the realist mode, is widely accepted as being of high quality, and is given extended treatment, together with briefer accounts of three other early works, The Shaving of Shagpat (1855), Evan Harrington (1861), and Rhoda Fleming (1865), and one from Meredith’s middle period, Beauchamp’s Career (1876). Two more novels of this period, The Egoist (1879) and Diana of the Crossways (1885), are generally considered to be among his best works, and their heroines are given chapters to themselves (3 and 4). Chapter 5 provides further contextualization for the changing socio-political circumstances of the 1880s and 1890s, with particular reference to that heightening of feminist consciousness represented by the short-lived ‘New Woman’ phenomenon, to which Diana of the Crossways had been considered by some to be a contribution. Brief discussion of some other ‘New Woman’ novels of the 80s and 90s follows, giving literary context to the heroines of Meredith’s three late candidates in the genre, One of Our Conquerors (1891), Lord Ormont and His Aminta (1894), and The Amazing Marriage (1895). The dissertation concludes with a glance at Meredith’s influence on a few early twentieth-century novelists.
- Full Text:
- Date Issued: 2008
- Authors: Bell, Alan Nigel
- Date: 2008
- Subjects: Meredith, George, 1828-1909 -- Criticism and interpretation Meredith, George, 1828-1909. Egoist Meredith, George, 1828-1909. Diana of the Crossways English fiction -- 19th century -- History and criticism English fiction -- Male authors -- History and criticism
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2203 , http://hdl.handle.net/10962/d1002245
- Description: Focusing on four early works, then three from his middle period and three from the 1890s, this dissertation explores Meredith’s role as a novelist in the unfolding of a social and literary paradox, namely, that with the death of George Eliot in 1880, the dominant writers of fiction were male, and this remained the case until the advent of Virginia Woolf, while at the same time the woman’s movement for emancipation in all spheres of life—domestic, commercial, professional and political—was gathering in strength and conviction. None of the late nineteenth-century male novelists—James, Hardy, Moore and Gissing, as well as Meredith—was ideologically committed to the feminist cause; in fact the very term ‘feminist’ did not begin to become current in England until the mid-1890s. But they were all interested in one aspect or another of the ‘Woman Question’, even if James was ambivalent about female emancipation, and Gissing, on the whole, was somewhat hostile. Of all these novelists, it was Meredith whose work, especially in its last two decades, most copiously reveals a profound sympathy for women and their struggles to realize their desires and ambitions, both inside and outside the home, in a patriarchal world. The dissertation therefore concentrates on his presentation of his heroines in their relationships with the men who, in one way or another, dominate them, and with whom they must negotiate, within the social and sexual conventions of the time, a modus vivendi—a procedure that will entail, especially in the later work, some transgression of those conventions. Chapter 1 sketches more than two centuries of development in female consciousness of severe social disadvantage, from literary observations in the mid-seventeenth century to the intensifying of political representations in the writings of Mary Wollstonecraft, and the rise of the woman’s movement in the course of the Victorian century. The chapter includes an account of the impact on Meredith of John Stuart Mill’s The Subjection of Women (1869), and an examination of some of his female friendships by way of illuminating the experiential component of his insights into the ‘Woman Question’ as reflected in his fiction and letters. His unhappy first marriage is reserved for consideration in Chapter 2, as background to the discussion of The Ordeal of Richard Feverel (1859). This early novel, Meredith’s first in the realist mode, is widely accepted as being of high quality, and is given extended treatment, together with briefer accounts of three other early works, The Shaving of Shagpat (1855), Evan Harrington (1861), and Rhoda Fleming (1865), and one from Meredith’s middle period, Beauchamp’s Career (1876). Two more novels of this period, The Egoist (1879) and Diana of the Crossways (1885), are generally considered to be among his best works, and their heroines are given chapters to themselves (3 and 4). Chapter 5 provides further contextualization for the changing socio-political circumstances of the 1880s and 1890s, with particular reference to that heightening of feminist consciousness represented by the short-lived ‘New Woman’ phenomenon, to which Diana of the Crossways had been considered by some to be a contribution. Brief discussion of some other ‘New Woman’ novels of the 80s and 90s follows, giving literary context to the heroines of Meredith’s three late candidates in the genre, One of Our Conquerors (1891), Lord Ormont and His Aminta (1894), and The Amazing Marriage (1895). The dissertation concludes with a glance at Meredith’s influence on a few early twentieth-century novelists.
- Full Text:
- Date Issued: 2008
Excavating the 'critique' : an investigation into disjunctions between the espoused and the practiced within a Fine Art studio practice curriculum
- Authors: Belluigi, Dina Zoe
- Date: 2008
- Subjects: Art -- Study and teaching (Higher) Postmodernism and education Universities and colleges -- Philosophy Universities and colleges -- Curricula Education, Higher -- Political aspects Creative thinking -- Study and teaching Discourse analysis -- Methodology Critical pedagogy
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1531 , http://hdl.handle.net/10962/d1003413
- Description: This report presents the findings of a case study excavating the event of the ‘Critique’ (crit), the formative assessment method within a Fine Art Studio Practice curriculum. Arguments informed by critical postmodernism, education theories and contemporary art criticism are utilised to construct a dialectic of higher education, contemporary art and fine art studio practice. An emphasis is placed on the importance of agency, expressed through intentionality and critical thinking, with a recognition of the relationship between ‘the self’ and ‘the other’. Using critical discourse analysis, the disjunctions between the espoused and practiced curriculum are explored. The researcher analyses how the assessment practices of the case studied are influenced by unexamined agentic factors, such as inter-departmental relations, lecturers’ assumptions and prior learning, and structural determinants, such as the medium-specific Bachelor of Fine Art degree structure and prevailing artistic traditions. The research findings indicate that these are underpinned by tensions between two orientations, the espoused curriculum’s discourse-interest informed by critical theory, and the theory-in-use. The latter is shown to have unexamined modernist leanings towards formalism and a master-apprentice relationship between lecturer and students, which encourages reproduction rather than critical, creative thinking. The dominant discourses in the case studied construct a negative dialectic of the artist-student that can be seen to deny student agency and authorial responsibility. Findings suggest that students experience this as alienating, to the extent that to preserve their sense of self, they adopted surface and strategic approaches to learning. An argument is made for lecturers’ critically reflexive engagement with their teaching practice, and thereby to model ethical relationships between ‘self’ and ‘other’ during ‘crits’. In addition, emphasis is placed on how assessment practices should be more aligned with the espoused curriculum, so that the importance of a reflexive relationship between form and content, process and product, intentionality and interpretation is acknowledged.
- Full Text:
- Date Issued: 2008
- Authors: Belluigi, Dina Zoe
- Date: 2008
- Subjects: Art -- Study and teaching (Higher) Postmodernism and education Universities and colleges -- Philosophy Universities and colleges -- Curricula Education, Higher -- Political aspects Creative thinking -- Study and teaching Discourse analysis -- Methodology Critical pedagogy
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1531 , http://hdl.handle.net/10962/d1003413
- Description: This report presents the findings of a case study excavating the event of the ‘Critique’ (crit), the formative assessment method within a Fine Art Studio Practice curriculum. Arguments informed by critical postmodernism, education theories and contemporary art criticism are utilised to construct a dialectic of higher education, contemporary art and fine art studio practice. An emphasis is placed on the importance of agency, expressed through intentionality and critical thinking, with a recognition of the relationship between ‘the self’ and ‘the other’. Using critical discourse analysis, the disjunctions between the espoused and practiced curriculum are explored. The researcher analyses how the assessment practices of the case studied are influenced by unexamined agentic factors, such as inter-departmental relations, lecturers’ assumptions and prior learning, and structural determinants, such as the medium-specific Bachelor of Fine Art degree structure and prevailing artistic traditions. The research findings indicate that these are underpinned by tensions between two orientations, the espoused curriculum’s discourse-interest informed by critical theory, and the theory-in-use. The latter is shown to have unexamined modernist leanings towards formalism and a master-apprentice relationship between lecturer and students, which encourages reproduction rather than critical, creative thinking. The dominant discourses in the case studied construct a negative dialectic of the artist-student that can be seen to deny student agency and authorial responsibility. Findings suggest that students experience this as alienating, to the extent that to preserve their sense of self, they adopted surface and strategic approaches to learning. An argument is made for lecturers’ critically reflexive engagement with their teaching practice, and thereby to model ethical relationships between ‘self’ and ‘other’ during ‘crits’. In addition, emphasis is placed on how assessment practices should be more aligned with the espoused curriculum, so that the importance of a reflexive relationship between form and content, process and product, intentionality and interpretation is acknowledged.
- Full Text:
- Date Issued: 2008
Optimisation of a sampling protocol for long-term monitoring of temperate reef fishes
- Authors: Bennett, Rhett Hamilton
- Date: 2008
- Subjects: Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5309 , http://hdl.handle.net/10962/d1005154 , Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Description: Marine Protected Areas (MPAs), the Ecosystem Approach to Fisheries management (EAF) and Integrated Coastal Management (ICM) have been identified as possible alternatives to traditional linefish management measures, which have largely failed. Monitoring and assessment of fish communities on a long-term basis is necessary, and will provide a means to evaluate the effectiveness of such management measures. Therefore, standardised protocols and optimal sampling methods for long-term monitoring (LTM) and assessment of coastal fish communities are essential. This study aimed to identify suitable methods and develop a protocol for assessment of inshore reef fish communities. A suitable location for evaluation of proposed methods was identified in the warm temperate biogeographical region of South Africa, encompassing the well-established Tsitsikamma Coastal National Park MPA and an adjacent exploited area. Chrysoblephus laticeps (roman) was identified as an indicator species for the study, as it has been well-studied and is well represented in the area. Underwater visual census (UVC) and controlled fishing were identified as suitable methods. UVC transects were found to be superior to point counts, in terms of sampling efficiency, variability, bias and required sample size. An effort of two angler hours per fishing station was shown to provide low catch variability, while at the same time a representative catch and low overall cost and required time. The methods were incorporated in a proposed sampling protocol, and evaluated. The methods were able to detect known differences between protected and exploited communities. It is recommended that LTM within protected areas, for detection of natural change, be focused on community-level indicators, while LTM in exploited areas, aimed at detection of anthropogenic change, be focused on species-level indicators. The proposed protocol with standardised methods will allow for comparisons across a network of LTM sites and provide the opportunity for a broad-scale assessment of the effects of environmental variables on reef fish stocks. The protocol developed in this study has application in other biogeographical regions in South Africa, and other parts of the world. Shift in the focus of much marine research, in South Africa and elsewhere, to LTM, highlights the relevance and timeous nature of this study.
- Full Text:
- Date Issued: 2008
- Authors: Bennett, Rhett Hamilton
- Date: 2008
- Subjects: Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5309 , http://hdl.handle.net/10962/d1005154 , Marine parks and reserves -- South Africa , Coastal zone management -- South Africa , Fishery management -- South Africa , Reef fishes -- South Africa , Fish communities -- South Africa , Fish stock assessment
- Description: Marine Protected Areas (MPAs), the Ecosystem Approach to Fisheries management (EAF) and Integrated Coastal Management (ICM) have been identified as possible alternatives to traditional linefish management measures, which have largely failed. Monitoring and assessment of fish communities on a long-term basis is necessary, and will provide a means to evaluate the effectiveness of such management measures. Therefore, standardised protocols and optimal sampling methods for long-term monitoring (LTM) and assessment of coastal fish communities are essential. This study aimed to identify suitable methods and develop a protocol for assessment of inshore reef fish communities. A suitable location for evaluation of proposed methods was identified in the warm temperate biogeographical region of South Africa, encompassing the well-established Tsitsikamma Coastal National Park MPA and an adjacent exploited area. Chrysoblephus laticeps (roman) was identified as an indicator species for the study, as it has been well-studied and is well represented in the area. Underwater visual census (UVC) and controlled fishing were identified as suitable methods. UVC transects were found to be superior to point counts, in terms of sampling efficiency, variability, bias and required sample size. An effort of two angler hours per fishing station was shown to provide low catch variability, while at the same time a representative catch and low overall cost and required time. The methods were incorporated in a proposed sampling protocol, and evaluated. The methods were able to detect known differences between protected and exploited communities. It is recommended that LTM within protected areas, for detection of natural change, be focused on community-level indicators, while LTM in exploited areas, aimed at detection of anthropogenic change, be focused on species-level indicators. The proposed protocol with standardised methods will allow for comparisons across a network of LTM sites and provide the opportunity for a broad-scale assessment of the effects of environmental variables on reef fish stocks. The protocol developed in this study has application in other biogeographical regions in South Africa, and other parts of the world. Shift in the focus of much marine research, in South Africa and elsewhere, to LTM, highlights the relevance and timeous nature of this study.
- Full Text:
- Date Issued: 2008
An investigation into the synergistic association between the major Clostridium cellulovorans cellulosomal endoglucanase and two hemicellulases on plant cell wall degradation
- Authors: Beukes, Natasha
- Date: 2008
- Subjects: Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3968 , http://hdl.handle.net/10962/d1004027 , Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
- Description: The cellulosome is a multimeric enzyme complex that has the ability to metabolise a wide variety of carbonaceous compounds. Cellulosomal composition may vary according to the microbe’s nutritional requirement and allows for the anaerobic degradation of complex substrates. The complex substrates of interest in this research study were sugarcane bagasse and pineapple fibre waste, as they represent two important lignocellulosic, South African agricultural crops. The effective degradation of complex plant biomass wastes may present a valuable source of renewable compounds for the production of a variety of biofuels, for example bioethanol, and a variety of biocomposites of industrial importance. The identification of renewable energy sources for the production of biofuels is becoming increasingly important, as a result of the rapid depletion of the fossil fuels that are traditionally used as energy sources. An effective means of completely degrading lignocellulose biomass still remains elusive due to the complex heterogeneity of the substrate structure, and the fact that the effective degradation of the substrate requires a consortium of enzymes. The cellulosome not only provides a variety of enzymes with varying specificities, but also promote a close proximity between the catalytic components (enzymes). The close proximity between the enzymes promotes the synergistic degradation of complex plant biomass for the production of valuable energy products. Previous synergy studies have focused predominantly on the synergistic associations between cellulases; however, the synergy between hemicellulases has occasionally been documented. This research project established the synergistic associations between two Clostridium cellulovorans hemicellulases that may be incorporated into the cellulosome and a cellulosomal endoglucanase that is conserved in all cellulosomes. This research study indicated that there was indeed a synergistic degradation of the complex plant biomass (sugarcane bagasse and pineapple fibre). The degrees of synergy and the ratio of the enzymes varied between the two complex substrates. The initial degradation of the bagasse required the presence of all the enzymes and proceeded at an enhanced rate under sulphidogenic conditions; however, there was a low production of fermentable sugars. The low quantity of fermentable sugars produced by the degradation of the bagasse may be related to the chemical composition of the substrate. The sugarcane contains a high percentage of lignin forming a protective layer around the holocellulose, thus the glycosidic bonds are shielded extensively from enzymatic attack. In comparison, the initial degradation of the pineapple fibre required the action of hemicellulases, and proceeded at an enhanced rate under sulphidogenic conditions. The initial degradation of the pineapple fibre produced a substantially larger quantity of fermentable sugars in comparison to the bagasse. The higher production of fermentable sugars from the degradation of the pineapple fibre may be explained by the fact that this substrate may have a lower percentage of lignin than the bagasse, thus allowing a larger percentage of the glycosidic bonds to be exposed to enzymatic attack. The data obtained also indicated that the glycosidic bonds from the hemicellulosic components of the pineapple fibre shielded the glycosidic bonds of the cellulose component. The identification of the chemical components of the different substrates may allow for the initial development of an ideal enzyme complex (designer cellulosome) with enzymes in an ideal ratio with optimal synergy that will effectively degrade the complex plant biomass substrate.
- Full Text:
- Date Issued: 2008
- Authors: Beukes, Natasha
- Date: 2008
- Subjects: Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3968 , http://hdl.handle.net/10962/d1004027 , Clostridium , Cellulose , Hemicellulose , Cellulase , Biomass conversion , Biomass energy -- South Africa , Energy crops -- South Africa , Bagasse -- Biodegradation , Pineapple -- Biodegradation
- Description: The cellulosome is a multimeric enzyme complex that has the ability to metabolise a wide variety of carbonaceous compounds. Cellulosomal composition may vary according to the microbe’s nutritional requirement and allows for the anaerobic degradation of complex substrates. The complex substrates of interest in this research study were sugarcane bagasse and pineapple fibre waste, as they represent two important lignocellulosic, South African agricultural crops. The effective degradation of complex plant biomass wastes may present a valuable source of renewable compounds for the production of a variety of biofuels, for example bioethanol, and a variety of biocomposites of industrial importance. The identification of renewable energy sources for the production of biofuels is becoming increasingly important, as a result of the rapid depletion of the fossil fuels that are traditionally used as energy sources. An effective means of completely degrading lignocellulose biomass still remains elusive due to the complex heterogeneity of the substrate structure, and the fact that the effective degradation of the substrate requires a consortium of enzymes. The cellulosome not only provides a variety of enzymes with varying specificities, but also promote a close proximity between the catalytic components (enzymes). The close proximity between the enzymes promotes the synergistic degradation of complex plant biomass for the production of valuable energy products. Previous synergy studies have focused predominantly on the synergistic associations between cellulases; however, the synergy between hemicellulases has occasionally been documented. This research project established the synergistic associations between two Clostridium cellulovorans hemicellulases that may be incorporated into the cellulosome and a cellulosomal endoglucanase that is conserved in all cellulosomes. This research study indicated that there was indeed a synergistic degradation of the complex plant biomass (sugarcane bagasse and pineapple fibre). The degrees of synergy and the ratio of the enzymes varied between the two complex substrates. The initial degradation of the bagasse required the presence of all the enzymes and proceeded at an enhanced rate under sulphidogenic conditions; however, there was a low production of fermentable sugars. The low quantity of fermentable sugars produced by the degradation of the bagasse may be related to the chemical composition of the substrate. The sugarcane contains a high percentage of lignin forming a protective layer around the holocellulose, thus the glycosidic bonds are shielded extensively from enzymatic attack. In comparison, the initial degradation of the pineapple fibre required the action of hemicellulases, and proceeded at an enhanced rate under sulphidogenic conditions. The initial degradation of the pineapple fibre produced a substantially larger quantity of fermentable sugars in comparison to the bagasse. The higher production of fermentable sugars from the degradation of the pineapple fibre may be explained by the fact that this substrate may have a lower percentage of lignin than the bagasse, thus allowing a larger percentage of the glycosidic bonds to be exposed to enzymatic attack. The data obtained also indicated that the glycosidic bonds from the hemicellulosic components of the pineapple fibre shielded the glycosidic bonds of the cellulose component. The identification of the chemical components of the different substrates may allow for the initial development of an ideal enzyme complex (designer cellulosome) with enzymes in an ideal ratio with optimal synergy that will effectively degrade the complex plant biomass substrate.
- Full Text:
- Date Issued: 2008
Ray Charles: a psychobiographical study
- Authors: Biggs, Ilze
- Date: 2008
- Subjects: Charles, Ray, 1930-2004 Psychology -- Biographical methods -- Case studies Jazz singers -- Biography Blind entertainers -- Psychology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2933 , http://hdl.handle.net/10962/d1002442
- Description: Psychobiography is the formulation of an individual's narrative according to a psychological theory. Psychobiographical researchers face a number of challenges. One pertinent challenge is the limited amount of psychobiographical research conducted at academic institutions, including South Africa. Although a number of studies had been completed in the past decade, the impact of psychobiographical research remains negligible. Although much has been written about Ray Charles, none of the existing literature adopted a specific psychological focus. Charles developed from a young boy in a poverty stricken, racially segregated society into an exceptionally successful musician who worked productively until he died at the age of 73. He was selected as the subject on the basis of interest value, uniqueness and significance of life achievements. The primary aim of this study was to explore and describe the development of Charles according to Levinson's (Levinson, et. ai, 1978) theoretical framework. Levinson's theory of adult development identifies and describes the important changes that occur throughout the lifespan of an individual. A secondary aim was to provide an understanding of Charles within the social, economic and historical context in which he lived. The data collection and analysis was conducted according to Yin's (2003) 'analytic generalization'. The data was analysed according to three linked sub-processes proposed by Huberman and Miles (1994).
- Full Text:
- Date Issued: 2008
- Authors: Biggs, Ilze
- Date: 2008
- Subjects: Charles, Ray, 1930-2004 Psychology -- Biographical methods -- Case studies Jazz singers -- Biography Blind entertainers -- Psychology
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2933 , http://hdl.handle.net/10962/d1002442
- Description: Psychobiography is the formulation of an individual's narrative according to a psychological theory. Psychobiographical researchers face a number of challenges. One pertinent challenge is the limited amount of psychobiographical research conducted at academic institutions, including South Africa. Although a number of studies had been completed in the past decade, the impact of psychobiographical research remains negligible. Although much has been written about Ray Charles, none of the existing literature adopted a specific psychological focus. Charles developed from a young boy in a poverty stricken, racially segregated society into an exceptionally successful musician who worked productively until he died at the age of 73. He was selected as the subject on the basis of interest value, uniqueness and significance of life achievements. The primary aim of this study was to explore and describe the development of Charles according to Levinson's (Levinson, et. ai, 1978) theoretical framework. Levinson's theory of adult development identifies and describes the important changes that occur throughout the lifespan of an individual. A secondary aim was to provide an understanding of Charles within the social, economic and historical context in which he lived. The data collection and analysis was conducted according to Yin's (2003) 'analytic generalization'. The data was analysed according to three linked sub-processes proposed by Huberman and Miles (1994).
- Full Text:
- Date Issued: 2008
The feeding and spatial ecologies of the large carnivore guild on Kwandwe Private Game Reserve
- Authors: Bissett, Charlene
- Date: 2008
- Subjects: Wildlife conservation -- South Africa -- Eastern Cape Kwandwe Private Game Reserve Lion -- Behavior -- South Africa -- Eastern Cape Lion -- Nutrition -- South Africa -- Eastern Cape Cheetah -- Behavior -- South Africa -- Eastern Cape Cheetah -- Nutrition -- South Africa -- Eastern Cape African wild dog -- South Africa -- Eastern Cape Spatial behavior in animals Predation (Biology) Game reserves -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5802 , http://hdl.handle.net/10962/d1006195
- Description: The reintroduction of lions, cheetahs and African wild dogs to Kwandwe Private Game Reserve in the Eastern Cape Province of South Africa created the opportunity to study the biology and behaviour of these large carnivores in an enclosed system. The research focused on space utilisation and feeding ecology of the predators, using standard observational methods. Changes in the structure of the carnivore guild, and changes in the prey base that occurred during the study were used as natural experiments to examine factors affecting space use and diet. In general, the diets of the predators were similar to previous studies and prey abundance was more important than prey species size in determining prey selection. Changes in the abundance of certain prey species was matched by a dietary switch in lions from kudu to warthog and an increase in the proportion of springbok kills by the cheetahs. There was no significant difference in the proportions of prey species detected by ad hoc or continuous observations. Core areas occupied by the predators were significantly smaller than home ranges except when females were denning. Home ranges overlapped both within and between species, but there was very little overlap of core areas. An increase in the number of lion prides in the area during the study resulted in an increase in overlap of home ranges of lions and cheetahs, but did not result in a change in home range size. Space use by female cheetahs with cubs increased as the cubs grew older. The use of thicket vegetation by cheetahs decreased with an increase in the number of lion prides. Minimum Daily Energy Expenditure, energy intake and net benefit were calculated for the predators using data from continuous observations. All predators exhibited a large net benefit and the net benefit for single female cheetahs was greater than for the members of the coalition. Net benefit for the alpha pair of African wild dogs was lower than that of the pack.
- Full Text:
- Date Issued: 2008
- Authors: Bissett, Charlene
- Date: 2008
- Subjects: Wildlife conservation -- South Africa -- Eastern Cape Kwandwe Private Game Reserve Lion -- Behavior -- South Africa -- Eastern Cape Lion -- Nutrition -- South Africa -- Eastern Cape Cheetah -- Behavior -- South Africa -- Eastern Cape Cheetah -- Nutrition -- South Africa -- Eastern Cape African wild dog -- South Africa -- Eastern Cape Spatial behavior in animals Predation (Biology) Game reserves -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5802 , http://hdl.handle.net/10962/d1006195
- Description: The reintroduction of lions, cheetahs and African wild dogs to Kwandwe Private Game Reserve in the Eastern Cape Province of South Africa created the opportunity to study the biology and behaviour of these large carnivores in an enclosed system. The research focused on space utilisation and feeding ecology of the predators, using standard observational methods. Changes in the structure of the carnivore guild, and changes in the prey base that occurred during the study were used as natural experiments to examine factors affecting space use and diet. In general, the diets of the predators were similar to previous studies and prey abundance was more important than prey species size in determining prey selection. Changes in the abundance of certain prey species was matched by a dietary switch in lions from kudu to warthog and an increase in the proportion of springbok kills by the cheetahs. There was no significant difference in the proportions of prey species detected by ad hoc or continuous observations. Core areas occupied by the predators were significantly smaller than home ranges except when females were denning. Home ranges overlapped both within and between species, but there was very little overlap of core areas. An increase in the number of lion prides in the area during the study resulted in an increase in overlap of home ranges of lions and cheetahs, but did not result in a change in home range size. Space use by female cheetahs with cubs increased as the cubs grew older. The use of thicket vegetation by cheetahs decreased with an increase in the number of lion prides. Minimum Daily Energy Expenditure, energy intake and net benefit were calculated for the predators using data from continuous observations. All predators exhibited a large net benefit and the net benefit for single female cheetahs was greater than for the members of the coalition. Net benefit for the alpha pair of African wild dogs was lower than that of the pack.
- Full Text:
- Date Issued: 2008
The antecedents of customer satisfaction in a financial institution : a qualitative study
- Authors: Bleske, Adrian
- Date: 2008
- Subjects: Standard Bank Properties , Banks and banking -- South Africa , Banks and banking -- Customer services -- South Africa , Financial services industry -- South Africa , Bank management -- South Africa , Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:840 , http://hdl.handle.net/10962/d1015482
- Description: The following is a case study report on the Cape Town business unit of Standard Bank Properties. The research project falls within the ambit of services marketing which introduces several unique management challenges for service businesses that sell services as a core offering. The principal aim of the case study is to gain an understanding of why customers bank at the business unit and to discover what aspects are critical to customer satisfaction. A further goal of the research is to examine how the business unit could improve customer satisfaction and to highlight any impediments to further improving customer satisfaction at the business unit. It is generally regarded that quality customer service is essential to building customer relationships and hence the research project emphasis on services marketing and customer satisfaction within a financial services context. The paper commences with an overview of the South African Banking Sector and its unique challenges such as the Financial Service Charter and newly introduced legislation such as Financial Intelligence Centre Act. The case study will specifically investigate the property finance industry and a detailed analysis of the business unit's operations and process flow will also be undertaken. The reason for this background information is to assist the reader to understand how the business unit operates. The research project will investigate four unique differences between goods marketing and services marketing whereafter three theoretical propositions are introduced, namely the dyadic interaction and service encounter, the Service Profit Chain and finally Relationship Marketing. Evidence in the form of a narrative will be led from insights obtained from interviews conducted with customers and staff at the business unit against these propositions with support (or otherwise) from independent surveys and documents from the business unit. The result of this analysis is the identification of several areas of concern specifically: New employees and the service encounter, Problems with FICA, Lack of a customer complaint handling system, Empowerment issues, Turnaround times, Reliance on key staff These insights together with the evidence from the literature review will be analysed and several recommendations made to improve customer service and ultimately customer satisfaction at the business unit. Several recommendations for further research are offered as well as the identification of limitations including but not limited to the specificity of the case study report.
- Full Text:
- Date Issued: 2008
- Authors: Bleske, Adrian
- Date: 2008
- Subjects: Standard Bank Properties , Banks and banking -- South Africa , Banks and banking -- Customer services -- South Africa , Financial services industry -- South Africa , Bank management -- South Africa , Banks and banking -- Customer services -- Effect of marketing on
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:840 , http://hdl.handle.net/10962/d1015482
- Description: The following is a case study report on the Cape Town business unit of Standard Bank Properties. The research project falls within the ambit of services marketing which introduces several unique management challenges for service businesses that sell services as a core offering. The principal aim of the case study is to gain an understanding of why customers bank at the business unit and to discover what aspects are critical to customer satisfaction. A further goal of the research is to examine how the business unit could improve customer satisfaction and to highlight any impediments to further improving customer satisfaction at the business unit. It is generally regarded that quality customer service is essential to building customer relationships and hence the research project emphasis on services marketing and customer satisfaction within a financial services context. The paper commences with an overview of the South African Banking Sector and its unique challenges such as the Financial Service Charter and newly introduced legislation such as Financial Intelligence Centre Act. The case study will specifically investigate the property finance industry and a detailed analysis of the business unit's operations and process flow will also be undertaken. The reason for this background information is to assist the reader to understand how the business unit operates. The research project will investigate four unique differences between goods marketing and services marketing whereafter three theoretical propositions are introduced, namely the dyadic interaction and service encounter, the Service Profit Chain and finally Relationship Marketing. Evidence in the form of a narrative will be led from insights obtained from interviews conducted with customers and staff at the business unit against these propositions with support (or otherwise) from independent surveys and documents from the business unit. The result of this analysis is the identification of several areas of concern specifically: New employees and the service encounter, Problems with FICA, Lack of a customer complaint handling system, Empowerment issues, Turnaround times, Reliance on key staff These insights together with the evidence from the literature review will be analysed and several recommendations made to improve customer service and ultimately customer satisfaction at the business unit. Several recommendations for further research are offered as well as the identification of limitations including but not limited to the specificity of the case study report.
- Full Text:
- Date Issued: 2008
Tripping over our own feet : a critical discussion of Trade Related Intellectual Property Rights (TRIPS) with specific reference to their impact on South Africa's ability to combat HIV and AIDS
- Authors: Brennan, Jade
- Date: 2008
- Subjects: Agreement on Trade-Related Aspects of Intellectual Property Rights, (1994) Trade regulation -- South Africa Intellectual property -- South Africa HIV (Viruses) -- South Africa AIDS (Disease) -- South Africa Patients -- Civil rights -- South Africa Human rights -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2850 , http://hdl.handle.net/10962/d1006316
- Description: This thesis aims to look at the agreement on Trade Related Intellectual Property Rights (TRIPS) with specific reference to their impact on South Africa's ability to combat HIV and AIDS. It begins by looking at the history of patents and intellectual property rights and illustrates why and how the TRIPS Agreement came into existence. The TRIPS Agreement exemplifies the disparities between developed and developing countries and this can clearly be seen with regard to the provision of anti-HIV and AIDS drugs. The developing world deals with the bulk of the HIV and AIDS epidemic whilst the developed world holds most of the patents on the medication needed to treat those living with HIV and AIDS. This situation lends itself to a rift between patient rights on the one hand, and patent rights on the other. Traditionally the state has been the provider of rights such as health, but TRIPS alters this to include strong patent protection that is in line with neo liberal doctrine. The thesis examines these tensions with specific reference to South Africa's ability successfully to implement programmes to combat HIV and AIDS.
- Full Text:
- Date Issued: 2008
- Authors: Brennan, Jade
- Date: 2008
- Subjects: Agreement on Trade-Related Aspects of Intellectual Property Rights, (1994) Trade regulation -- South Africa Intellectual property -- South Africa HIV (Viruses) -- South Africa AIDS (Disease) -- South Africa Patients -- Civil rights -- South Africa Human rights -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2850 , http://hdl.handle.net/10962/d1006316
- Description: This thesis aims to look at the agreement on Trade Related Intellectual Property Rights (TRIPS) with specific reference to their impact on South Africa's ability to combat HIV and AIDS. It begins by looking at the history of patents and intellectual property rights and illustrates why and how the TRIPS Agreement came into existence. The TRIPS Agreement exemplifies the disparities between developed and developing countries and this can clearly be seen with regard to the provision of anti-HIV and AIDS drugs. The developing world deals with the bulk of the HIV and AIDS epidemic whilst the developed world holds most of the patents on the medication needed to treat those living with HIV and AIDS. This situation lends itself to a rift between patient rights on the one hand, and patent rights on the other. Traditionally the state has been the provider of rights such as health, but TRIPS alters this to include strong patent protection that is in line with neo liberal doctrine. The thesis examines these tensions with specific reference to South Africa's ability successfully to implement programmes to combat HIV and AIDS.
- Full Text:
- Date Issued: 2008
Melatonin and anticancer therapy interactions with 5-Fluorouracil
- Authors: Cassim, Layla
- Date: 2008
- Subjects: Melatonin Melatonin -- Therapeutic use Antineoplastic agents Fluorouracil Fluorouracil -- Toxicology Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3746 , http://hdl.handle.net/10962/d1003224
- Description: On the basis of clinical studies, some researchers have advocated that the neurohormone and antioxidant melatonin, shown to possess intrinsic anticancer properties, be used as co-therapy in cancer patients being treated with the antineoplastic agent 5-fluorouracil, as increased patient survival times and enhanced quality of life have been observed. The focus of this research was thus to investigate the mechanisms of this seemingly beneficial drug interaction between 5-fluorouracil and melatonin. Metabolism studies were undertaken, in which it was established that there is no hepatic metabolic drug interaction between these agents by cytochrome P450, and that neither agent alters the activity of this enzyme system. Co-therapy with melatonin is thus unlikely to alter plasma levels of 5-fluorouracil by this mechanism. Novel mechanisms by which 5-fluorouracil is toxic were elucidated, such as the induction of lipid peroxidation, due to the formation of reactive oxygen species; decreases in brain serotonin, dopamine and norepinephrine levels, possibly leading to depression; hippocampal shrinkage and morphological alterations and lysis of hippocampal cells, which may underlie cognitive impairment; and a reduction in the nociceptive threshold when administered acutely. All these deleterious effects are attenuated by the co-administration of melatonin, suggesting that the agent exhibits antidepressive and analgesic properties, in addition to its known antioxidative and free radical-scavenging abilities. This suggests that melatonin cotherapy can significantly decrease 5-fluorouracil-induced toxicity, but this may also exert a protective effect on cancer cells and thus compromise the anticancer efficacy of 5-fluorouracil. It was, furthermore, found that stimulation of indoleamine 2,3-dioxygenase activity, mediated by increases in superoxide anion and interferon-γ levels, may underlie resistance to 5-fluorouracil therapy. Melatonin was shown to increase superoxide anion levels in vivo, and this is believed to be by conversion to the metabolite and known oxidant 6- hydroxymelatonin. This highlights that the possible deleterious effects of melatonin metabolites should be studied further. Serum corticosterone levels and cytokine profiles are unaltered by both 5-FU and melatonin, suggesting that these agents may be used by HIV infected individuals without promoting the progression to AIDS. It can thus be concluded that melatonin co-therapy is potentially useful in countering 5-fluorouracil toxicity.
- Full Text:
- Date Issued: 2008
- Authors: Cassim, Layla
- Date: 2008
- Subjects: Melatonin Melatonin -- Therapeutic use Antineoplastic agents Fluorouracil Fluorouracil -- Toxicology Cancer -- Treatment
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3746 , http://hdl.handle.net/10962/d1003224
- Description: On the basis of clinical studies, some researchers have advocated that the neurohormone and antioxidant melatonin, shown to possess intrinsic anticancer properties, be used as co-therapy in cancer patients being treated with the antineoplastic agent 5-fluorouracil, as increased patient survival times and enhanced quality of life have been observed. The focus of this research was thus to investigate the mechanisms of this seemingly beneficial drug interaction between 5-fluorouracil and melatonin. Metabolism studies were undertaken, in which it was established that there is no hepatic metabolic drug interaction between these agents by cytochrome P450, and that neither agent alters the activity of this enzyme system. Co-therapy with melatonin is thus unlikely to alter plasma levels of 5-fluorouracil by this mechanism. Novel mechanisms by which 5-fluorouracil is toxic were elucidated, such as the induction of lipid peroxidation, due to the formation of reactive oxygen species; decreases in brain serotonin, dopamine and norepinephrine levels, possibly leading to depression; hippocampal shrinkage and morphological alterations and lysis of hippocampal cells, which may underlie cognitive impairment; and a reduction in the nociceptive threshold when administered acutely. All these deleterious effects are attenuated by the co-administration of melatonin, suggesting that the agent exhibits antidepressive and analgesic properties, in addition to its known antioxidative and free radical-scavenging abilities. This suggests that melatonin cotherapy can significantly decrease 5-fluorouracil-induced toxicity, but this may also exert a protective effect on cancer cells and thus compromise the anticancer efficacy of 5-fluorouracil. It was, furthermore, found that stimulation of indoleamine 2,3-dioxygenase activity, mediated by increases in superoxide anion and interferon-γ levels, may underlie resistance to 5-fluorouracil therapy. Melatonin was shown to increase superoxide anion levels in vivo, and this is believed to be by conversion to the metabolite and known oxidant 6- hydroxymelatonin. This highlights that the possible deleterious effects of melatonin metabolites should be studied further. Serum corticosterone levels and cytokine profiles are unaltered by both 5-FU and melatonin, suggesting that these agents may be used by HIV infected individuals without promoting the progression to AIDS. It can thus be concluded that melatonin co-therapy is potentially useful in countering 5-fluorouracil toxicity.
- Full Text:
- Date Issued: 2008
Synthesis, photochemical and photophysical properties of gallium and indium phthalocyanine derivatives
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
- Authors: Chauke, Vongani Portia
- Date: 2008
- Subjects: Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4375 , http://hdl.handle.net/10962/d1005040 , Phthalocyanines , Photochemotherapy , Electrochemistry , Gallium , Indium
- Description: The syntheses of octasubstituted and unsusbstitituted Gallium(III) chloride and indium(III) chloride phthalocyanines (GaPc and InPc), their photophysical, photochemical and nonlinear optical parameters are hereby presented. The photocatalytic oxidation of 1-hexene using the synthesized GaPc and InPc complexes as well as electrochemical characterization is also presented in this thesis. Fluorescence quantum yields do not vary much among the four Ga complexes, except for complex 21c; therefore it was concluded that the effect of substituents is not significant among them. Solvents however, had an effect on the results. Lower Φ[subscript F] values were obtained in low viscosity solvents like toluene, relative to highly viscous solvents, such as DMSO. The triplet quantum yields were found to be lower in DMSO than in DMF and toluene. The rate constants for fluorescence, intersystem crossing and internal conversion as well as fluorescence and triplet lifetimes are reported. Photodegradation and singlet oxygen quantum yields have also been reported. There was no clear correlation between the latter parameters. It was however established that the four gallium MPcs were stable, within the allowed stability range for phthalocyanines. High quantum yields of triplet state (Φ[subscript T] ranging from 0.70 to 0.91 in dimethysulfoxide, DMSO) and singlet oxygen generation (Φ[subscript greek capital letter delta], ranging from 0.61 to 0.79 in DMSO) were obtained. Short triplet lifetimes 50 to 60 μs were obtained in DMSO). Calculated non-linear parameters of these complexes are compared with those of the corresponding GaPc derivatives and tetrasubstituted GaPc and InPc complexes. The optical limiting threshold intensity (I[subscript lim]) values for the InPc and GaPc derivatives were calculated and compared with those of corresponding tetrasubstituted InPc and GaPc complexes. The octasubstituted were found to be better optical limiters. Photocatalytic oxidation of 1-hexene by GaPc (21a-c) and InPc (22a-c) derivatives is also presented. The photocatalytic oxidation products for 1-hexene were 1,2- epoxyhexane and 1-hexen-3-ol. The % conversion values of 1-hexene and % selectivity of 1,2-epoxyhexane were generally higher for InPc derivatives. Even though InPc derivatives showed better photocatalytic results than GaPc derivatives, the former were less stable relative to the latter. Both type I and type II mechanism were implicated in the photocatalysis mechanism.
- Full Text:
- Date Issued: 2008
The variability and predictability of the IRI shape parameters over Grahamstown, South Africa
- Authors: Chimidza, Oyapo
- Date: 2008
- Subjects: Ionosphere -- Mathematical models -- South Africa , Atmosphere, Upper -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5496 , http://hdl.handle.net/10962/d1005282 , Ionosphere -- Mathematical models -- South Africa , Atmosphere, Upper -- South Africa
- Description: The International Reference Ionosphere (IRI) shape parameters B0, B1, and D1 provide a representation of the shape of the F2 layer, the thickness of the F2 layer and the shape of the F1 layer of the ionosphere respectively. The aim of this study was to examine the variability of these parameters using Grahamstown, South Africa (33.3±S, 26.5±E) ionosonde data and determine their predictability by the IRI-2001 model. A further aim of this study was to investigate developing an alternative model for predicting these parameters. These parameters can be determined from electron density profiles that are inverted from ionograms recorded with an ionosonde. Data representing the B0, B1 and D1 parameters, with half hourly or hourly intervals, were scaled and deduced from the digital pulse sounder (DPS) ionosonde for the period April 1996 to December 2006. An analysis of the diurnal, seasonal, and solar variations of the behaviour of these parameters was undertaken for the years 2000, 2004 and 2005 using monthly medians. Comparisons between the observational results and that of the IRI model (IRI 2001 version) indicate that the IRI-2001 model does not accurately represent the diurnal and seasonal variation of the parameters. A preliminary model was thus developed using the technique of Neural Networks (NNs). All available data from the Grahamstown ionosonde from 1996 to 2006 were used in the training of the NNs and the prediction of the variation of the shape parameters. Inputs to the model were the day number, the hour of day, the solar activity and the magnetic index. Comparisons between the preliminary NN model and the IRI-2001 model indicated that the preliminary model was more accurate at the prediction of the parameters than the IRI-2001 model. This analysis showed the need to improve the existing IRI model or develop a new model for the South African region. This thesis describes the results from this feasibility study which show the variability and predictability of the IRI shape parameters.
- Full Text:
- Date Issued: 2008
- Authors: Chimidza, Oyapo
- Date: 2008
- Subjects: Ionosphere -- Mathematical models -- South Africa , Atmosphere, Upper -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5496 , http://hdl.handle.net/10962/d1005282 , Ionosphere -- Mathematical models -- South Africa , Atmosphere, Upper -- South Africa
- Description: The International Reference Ionosphere (IRI) shape parameters B0, B1, and D1 provide a representation of the shape of the F2 layer, the thickness of the F2 layer and the shape of the F1 layer of the ionosphere respectively. The aim of this study was to examine the variability of these parameters using Grahamstown, South Africa (33.3±S, 26.5±E) ionosonde data and determine their predictability by the IRI-2001 model. A further aim of this study was to investigate developing an alternative model for predicting these parameters. These parameters can be determined from electron density profiles that are inverted from ionograms recorded with an ionosonde. Data representing the B0, B1 and D1 parameters, with half hourly or hourly intervals, were scaled and deduced from the digital pulse sounder (DPS) ionosonde for the period April 1996 to December 2006. An analysis of the diurnal, seasonal, and solar variations of the behaviour of these parameters was undertaken for the years 2000, 2004 and 2005 using monthly medians. Comparisons between the observational results and that of the IRI model (IRI 2001 version) indicate that the IRI-2001 model does not accurately represent the diurnal and seasonal variation of the parameters. A preliminary model was thus developed using the technique of Neural Networks (NNs). All available data from the Grahamstown ionosonde from 1996 to 2006 were used in the training of the NNs and the prediction of the variation of the shape parameters. Inputs to the model were the day number, the hour of day, the solar activity and the magnetic index. Comparisons between the preliminary NN model and the IRI-2001 model indicated that the preliminary model was more accurate at the prediction of the parameters than the IRI-2001 model. This analysis showed the need to improve the existing IRI model or develop a new model for the South African region. This thesis describes the results from this feasibility study which show the variability and predictability of the IRI shape parameters.
- Full Text:
- Date Issued: 2008
An empirical analysis of the long-run comovement, dynamic returns linkages and volatility transmission between the world major and the South African stock markets
- Authors: Chinzara, Zivanemoyo
- Date: 2008
- Subjects: Stock exchanges -- South Africa , Globalization -- Economic aspects -- South Africa , International economic relations , Portfolio management -- South Africa , Monetary policy -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:970 , http://hdl.handle.net/10962/d1002704 , Stock exchanges -- South Africa , Globalization -- Economic aspects -- South Africa , International economic relations , Portfolio management -- South Africa , Monetary policy -- South Africa
- Description: The international linkages of stock markets have important implications for cost of capital and portfolio diversification. Recent trends in globalization, financial liberalization and financial innovation raises questions with regard to whether African stock markets are being integrated into world equity markets. This study examines the extent to which the South African (SA) equity market is integrated into the world equity markets using daily data for the period 1995-2007. The study is divided into three main parts, each looking at the different ways in which integration can be considered. The first investigates whether there is long run comovement between the SA and the major global equity markets. Both bivariate and multivariate Johansen (1988) and Johansen and Juselius (1990) cointegration approaches were utilised. Vector Error Correction Models (VECMs) are then estimated for portfolios which show evidence of cointegration. The second part analyses returns linkages using the Vector Autoregressive (VAR), block exogeneity, impulse response and variance decomposition. The third part examines the behaviour of volatility and volatility linkages among the stock markets. Firstly volatility is analysed using the GARCH, EGARCH and GJR GARCH. Simultaneously, the hypothesis that investors receive a premium for investing in more risky stock markets is explored using the GARCH-in mean. The long term trend of volatility is also examined. Volatility linkages are then analysed using the VAR, block exogeneity, impulse response and variance decomposition. The first part established that no bivariate cointegration exists between the SA and any of the stock markets being studied, implying that pairwise portfolio diversification is potentially worthwhile for SA portfolio managers. However, multivariate cointegration exists for some portfolios, with the US, UK, Germany and SA showing evidence of error correction for some of these portfolios. Findings on return linkages is that there are significant returns linkages among the markets, with the US and SA being the most exogenous and most endogenous respectively. Findings regarding volatility are that the volatility in all the markets is inherently asymmetric and that except for the US there is no risk premium in any of the markets. The long term trend of volatility in all the stock markets was found to be relatively stable. The final finding was that significant volatility linkages exist among the markets, with the US being the most exogenous and SA and China showing evidence of bidirectional linkages. Overall, except for volatility linkages, the integration of SA into the global equity markets is still quite low. Thus, both SA and international investors can capitalise on this portfolio diversification potential. On the other hand, policy makers should capitalise on this and make policies that will attract the much needed foreign investors.
- Full Text:
- Date Issued: 2008
- Authors: Chinzara, Zivanemoyo
- Date: 2008
- Subjects: Stock exchanges -- South Africa , Globalization -- Economic aspects -- South Africa , International economic relations , Portfolio management -- South Africa , Monetary policy -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:970 , http://hdl.handle.net/10962/d1002704 , Stock exchanges -- South Africa , Globalization -- Economic aspects -- South Africa , International economic relations , Portfolio management -- South Africa , Monetary policy -- South Africa
- Description: The international linkages of stock markets have important implications for cost of capital and portfolio diversification. Recent trends in globalization, financial liberalization and financial innovation raises questions with regard to whether African stock markets are being integrated into world equity markets. This study examines the extent to which the South African (SA) equity market is integrated into the world equity markets using daily data for the period 1995-2007. The study is divided into three main parts, each looking at the different ways in which integration can be considered. The first investigates whether there is long run comovement between the SA and the major global equity markets. Both bivariate and multivariate Johansen (1988) and Johansen and Juselius (1990) cointegration approaches were utilised. Vector Error Correction Models (VECMs) are then estimated for portfolios which show evidence of cointegration. The second part analyses returns linkages using the Vector Autoregressive (VAR), block exogeneity, impulse response and variance decomposition. The third part examines the behaviour of volatility and volatility linkages among the stock markets. Firstly volatility is analysed using the GARCH, EGARCH and GJR GARCH. Simultaneously, the hypothesis that investors receive a premium for investing in more risky stock markets is explored using the GARCH-in mean. The long term trend of volatility is also examined. Volatility linkages are then analysed using the VAR, block exogeneity, impulse response and variance decomposition. The first part established that no bivariate cointegration exists between the SA and any of the stock markets being studied, implying that pairwise portfolio diversification is potentially worthwhile for SA portfolio managers. However, multivariate cointegration exists for some portfolios, with the US, UK, Germany and SA showing evidence of error correction for some of these portfolios. Findings on return linkages is that there are significant returns linkages among the markets, with the US and SA being the most exogenous and most endogenous respectively. Findings regarding volatility are that the volatility in all the markets is inherently asymmetric and that except for the US there is no risk premium in any of the markets. The long term trend of volatility in all the stock markets was found to be relatively stable. The final finding was that significant volatility linkages exist among the markets, with the US being the most exogenous and SA and China showing evidence of bidirectional linkages. Overall, except for volatility linkages, the integration of SA into the global equity markets is still quite low. Thus, both SA and international investors can capitalise on this portfolio diversification potential. On the other hand, policy makers should capitalise on this and make policies that will attract the much needed foreign investors.
- Full Text:
- Date Issued: 2008
Toward the development of a rearing protocol for juvenile dusky kob, Argyrosomus japonicus (Pisces: Sciaenidae)
- Authors: Collett, Paul David
- Date: 2008
- Subjects: Argyrosomus -- South Africa , Mariculture -- South Africa , Fishes -- Nutrition -- South Africa , Fishes -- Growth -- South Africa , Fish trade -- South Africa , Sciaenidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5325 , http://hdl.handle.net/10962/d1005171 , Argyrosomus -- South Africa , Mariculture -- South Africa , Fishes -- Nutrition -- South Africa , Fishes -- Growth -- South Africa , Fish trade -- South Africa , Sciaenidae
- Description: The South African mariculture industry is developing the rearing technology of indigenous fish species. Dusky kob (Argyrosomus japonicus) has high-quality flesh and a good market demand. Research is needed to determine the environmental requirements under which growth of dusky kob is optimised. This study assessed the effect of temperature, light intensity, feeding frequency and stocking density, respectively, on growth, feed conversion ratio (FCR) and survival of juvenile dusky kob within a weight range of 10-60 g fish⁻¹) in a series of four growth trials. The effect of temperature on growth and FCR was assessed at 14 temperatures from 17 to 28°C. The temperature for best growth was estimated to be 25.3 °C, while 21.4 °C was the temperature at which the best FCR was achieved. A growth trial testing the effect of light intensity on growth showed that light intensity did not affect growth in the range of 23 – 315 lx. Fish fed a restricted ration of 3.6% body weight per day (chapter 2) or 3.41% body weight per day (chapter 4) had a better FCR than fish fed to satiation. A trial to assess the effect of feeding frequency on growth and FCR showed that fish fed both two or three times daily grew better than those fed once daily. FCR was best in fish that were fed once or twice daily. Preliminary analysis of the results from a stocking density trial showed that stocking density in the range of 10 – 50 kg m⁻³ did not affect growth of juvenile dusky kob. It is recommended to culture dusky kob at a temperature of 25.3 - 21.4 °C at stocking densities up 50 kg m⁻³ to maximise growth. However, a study is needed to determine the environmental conditions needed to maximise profit under commercial conditions. The results allow the South African industry the opportunity to assess the culture potential of this species. In addition, the results will help develop protocols that can be used in other South African candidate aquaculture species such as silver kob, yellowtail, white-stumpnose and sole.
- Full Text:
- Date Issued: 2008
- Authors: Collett, Paul David
- Date: 2008
- Subjects: Argyrosomus -- South Africa , Mariculture -- South Africa , Fishes -- Nutrition -- South Africa , Fishes -- Growth -- South Africa , Fish trade -- South Africa , Sciaenidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5325 , http://hdl.handle.net/10962/d1005171 , Argyrosomus -- South Africa , Mariculture -- South Africa , Fishes -- Nutrition -- South Africa , Fishes -- Growth -- South Africa , Fish trade -- South Africa , Sciaenidae
- Description: The South African mariculture industry is developing the rearing technology of indigenous fish species. Dusky kob (Argyrosomus japonicus) has high-quality flesh and a good market demand. Research is needed to determine the environmental requirements under which growth of dusky kob is optimised. This study assessed the effect of temperature, light intensity, feeding frequency and stocking density, respectively, on growth, feed conversion ratio (FCR) and survival of juvenile dusky kob within a weight range of 10-60 g fish⁻¹) in a series of four growth trials. The effect of temperature on growth and FCR was assessed at 14 temperatures from 17 to 28°C. The temperature for best growth was estimated to be 25.3 °C, while 21.4 °C was the temperature at which the best FCR was achieved. A growth trial testing the effect of light intensity on growth showed that light intensity did not affect growth in the range of 23 – 315 lx. Fish fed a restricted ration of 3.6% body weight per day (chapter 2) or 3.41% body weight per day (chapter 4) had a better FCR than fish fed to satiation. A trial to assess the effect of feeding frequency on growth and FCR showed that fish fed both two or three times daily grew better than those fed once daily. FCR was best in fish that were fed once or twice daily. Preliminary analysis of the results from a stocking density trial showed that stocking density in the range of 10 – 50 kg m⁻³ did not affect growth of juvenile dusky kob. It is recommended to culture dusky kob at a temperature of 25.3 - 21.4 °C at stocking densities up 50 kg m⁻³ to maximise growth. However, a study is needed to determine the environmental conditions needed to maximise profit under commercial conditions. The results allow the South African industry the opportunity to assess the culture potential of this species. In addition, the results will help develop protocols that can be used in other South African candidate aquaculture species such as silver kob, yellowtail, white-stumpnose and sole.
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- Date Issued: 2008