Ligand isotope vibrational spectroscopic and DFT studies of Pt(II) and Cu(I) complexes
- Authors: Medina, Gerardo Juan
- Date: 2005
- Subjects: Ligands Spectrum analysis Vibrational spectra Infrared spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4324 , http://hdl.handle.net/10962/d1004982
- Description: Ligand-isotope labelling studies were performed on Zeise’s salt derivatives with pyridine N-oxide and quinoline N-oxide, their perdeuterated and O-18 isotopomers, C₂D₄ and ¹³CO, and the results of the vibrational analyses are reported. The isotopomers are modelled utilizing DFT calculations at the B3LYP level with the 6-31 G** basis set, and a pseudopotential level for the Pt atom. The calculated and observed structure and vibrational spectra correlate well. The crystal structures of [Pt(C₂2H₄)(pyO)Cl₂] and [Pt(CO)(quinO)Br₂] are reported. The frequency for the νPt-O vibration, ambiguously assigned in the literature, is here assigned unequivocally at 400 cm⁻¹. Previously observed, but inadequately described phenomena are addressed: the νN-O vibration in substituted quinoline N-oxides has been assigned previously at significantly different frequencies, depending on the nature of the substituent. This suggests that there is no specific mid-ir band associated with a high N-O character. A suitable explanation is presented for this phenomenon, showing that in low symmetry systems (eg. quinO) the N-O stretch is dispersed among several modes, whereas in high symmetry systems (eg. pyO) only a few limited modes have a high N-O character. A theoretical study of Cu(I) carbonyl compounds with macrocyclic ligands is presented. Local and global HSAB parameters applied to the donor and Cu atoms are used to explain the observed reactivities and the available spectroscopic data. Extended to [Cu(CO){H₂N(CH₂)[subscript n]NH(CH₂)[subscript m] NH₂}] BPh₄ (where n = 2, m = 2, 3 and n =3, m = 3, 4) and their -d₅ and ¹³CO isotopomers, subtle differences obtained experimentally for the CO stretching frequency in this series have been reproduced in the DFT calculations at the B3LYP level, using the 6-31 G* and 6-31 G** basis sets. Several properties (ligand pK[subscript a] values, νCO frequencies, etc.) correlate with some HSAB descriptors. Vibrational analyses are presented of Cu(I) carbonyl Schiff-base derivatives of N-Benzylidene-N’-[2-(benzyilidene-amino)-ethyl]-ethane-1,2-diamine, {2,2N3(C₆H₄R)₂}, and their -d₅ and ¹³CO isotopomers. The crystal structure of [Cu(CO){2,2N3(C₆H₅)₂}]BPh₄ is reported. From geometry optimizations and the HSAB descriptors, spectroscopic trends ([n]Cu-N and [nu]CO) are related to calculated global hardness and the Hammett substituent parameters, and are discussed in terms of σ-donation and π-backbonding of Cu- CO.
- Full Text:
- Date Issued: 2005
- Authors: Medina, Gerardo Juan
- Date: 2005
- Subjects: Ligands Spectrum analysis Vibrational spectra Infrared spectroscopy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4324 , http://hdl.handle.net/10962/d1004982
- Description: Ligand-isotope labelling studies were performed on Zeise’s salt derivatives with pyridine N-oxide and quinoline N-oxide, their perdeuterated and O-18 isotopomers, C₂D₄ and ¹³CO, and the results of the vibrational analyses are reported. The isotopomers are modelled utilizing DFT calculations at the B3LYP level with the 6-31 G** basis set, and a pseudopotential level for the Pt atom. The calculated and observed structure and vibrational spectra correlate well. The crystal structures of [Pt(C₂2H₄)(pyO)Cl₂] and [Pt(CO)(quinO)Br₂] are reported. The frequency for the νPt-O vibration, ambiguously assigned in the literature, is here assigned unequivocally at 400 cm⁻¹. Previously observed, but inadequately described phenomena are addressed: the νN-O vibration in substituted quinoline N-oxides has been assigned previously at significantly different frequencies, depending on the nature of the substituent. This suggests that there is no specific mid-ir band associated with a high N-O character. A suitable explanation is presented for this phenomenon, showing that in low symmetry systems (eg. quinO) the N-O stretch is dispersed among several modes, whereas in high symmetry systems (eg. pyO) only a few limited modes have a high N-O character. A theoretical study of Cu(I) carbonyl compounds with macrocyclic ligands is presented. Local and global HSAB parameters applied to the donor and Cu atoms are used to explain the observed reactivities and the available spectroscopic data. Extended to [Cu(CO){H₂N(CH₂)[subscript n]NH(CH₂)[subscript m] NH₂}] BPh₄ (where n = 2, m = 2, 3 and n =3, m = 3, 4) and their -d₅ and ¹³CO isotopomers, subtle differences obtained experimentally for the CO stretching frequency in this series have been reproduced in the DFT calculations at the B3LYP level, using the 6-31 G* and 6-31 G** basis sets. Several properties (ligand pK[subscript a] values, νCO frequencies, etc.) correlate with some HSAB descriptors. Vibrational analyses are presented of Cu(I) carbonyl Schiff-base derivatives of N-Benzylidene-N’-[2-(benzyilidene-amino)-ethyl]-ethane-1,2-diamine, {2,2N3(C₆H₄R)₂}, and their -d₅ and ¹³CO isotopomers. The crystal structure of [Cu(CO){2,2N3(C₆H₅)₂}]BPh₄ is reported. From geometry optimizations and the HSAB descriptors, spectroscopic trends ([n]Cu-N and [nu]CO) are related to calculated global hardness and the Hammett substituent parameters, and are discussed in terms of σ-donation and π-backbonding of Cu- CO.
- Full Text:
- Date Issued: 2005
Re-inventing educational leadership for school and community transformation: learning from the Educational Leadership Management and Development programme of the University of Fort Hare
- Authors: Moyo, George
- Date: 2005
- Subjects: University of Fort Hare. Educational Leadership Management and Development Educational leadership -- South Africa Educational change -- South Africa School management and organization -- South Africa School improvement programs -- South Africa School principals -- South Africa Community and school -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1719 , http://hdl.handle.net/10962/d1003602
- Description: This study explores educational leadership development and social change strategies pioneered by one programme, the Educational Leadership Management and Development (ELMD) programme of the University of Fort Hare. The programme seeks to model a way of doing social and educational transformation through educational leadership development. Conceptually, the model was meant to draw together a number of education stakeholders operating at various levels of the schooling system to undergo the same programme of leadership development. The programme participants, who included district education officials, schools principals, members of school management teams, educators and members of School Governing Bodies, were to enrol as teams. They would work on learning tasks that were both academic and practical in nature, with an emphasis on experiential learning that leads to the creation of district and community networks of partners, development teams or forums and communities of practice, as well as the production and implementation of district and school development plans. Informed by this conceptual position, the study was structured by two underlying questions. First, whether the ELMD was re-inventing educational leadership beyond the traditional focus on principalship towards one that is inclusive of other education stakeholders. Second, how leadership development as a vehicle for social and educational change can be carried out. The research process was guided by a multi-paradigm perspective which drew heavily on the interpretive and critical science orientations. This led to the crafting of research methods that looked for data that would assist in an understanding of what was happening in the programme, as well as what power dynamics were at play and with what consequences for innovation. The evidence emanating from the study suggests a number of possibilities for consideration by future leadership development programme designers. First, the ELMD programme delivery design shows what can be done to draw participants from various levels of the schooling system, district, school and community and teach them educational leadership together in a mode that mobilizes them for change. Second, how social distance separating different levels of the education hierarchy and status consciousness may disappear gradually as people are brought together to work on tasks of mutual concern. Third, after a year of engagement with ELMD ideas and approach, the participants in the programme appeared to have started a journey of selftransformation towards becoming qualitatively different people who saw themselves as teams capable of tackling education and social problems in their schools and communities. These participants had begun to forge working networks, but the extent to which these could be characterized as knowledge ecosystems and communities of practice remains a question to explore. Fourth, that the current higher education accreditation policies and practices do not accommodate innovative learning approaches of the kind that the ELMD is developing. In this regard, the ELMD experienced difficulties in coming up with an assessment policy and practices which meet the academic as well as the practical developmental concerns of the programme. Fifth, programme instrumentalities and mandates that are put in place do not, in themselves, bring about change. The actual change comes about through the actions of human leadership capable of navigating between structural enablers and constraints.
- Full Text:
- Date Issued: 2005
- Authors: Moyo, George
- Date: 2005
- Subjects: University of Fort Hare. Educational Leadership Management and Development Educational leadership -- South Africa Educational change -- South Africa School management and organization -- South Africa School improvement programs -- South Africa School principals -- South Africa Community and school -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1719 , http://hdl.handle.net/10962/d1003602
- Description: This study explores educational leadership development and social change strategies pioneered by one programme, the Educational Leadership Management and Development (ELMD) programme of the University of Fort Hare. The programme seeks to model a way of doing social and educational transformation through educational leadership development. Conceptually, the model was meant to draw together a number of education stakeholders operating at various levels of the schooling system to undergo the same programme of leadership development. The programme participants, who included district education officials, schools principals, members of school management teams, educators and members of School Governing Bodies, were to enrol as teams. They would work on learning tasks that were both academic and practical in nature, with an emphasis on experiential learning that leads to the creation of district and community networks of partners, development teams or forums and communities of practice, as well as the production and implementation of district and school development plans. Informed by this conceptual position, the study was structured by two underlying questions. First, whether the ELMD was re-inventing educational leadership beyond the traditional focus on principalship towards one that is inclusive of other education stakeholders. Second, how leadership development as a vehicle for social and educational change can be carried out. The research process was guided by a multi-paradigm perspective which drew heavily on the interpretive and critical science orientations. This led to the crafting of research methods that looked for data that would assist in an understanding of what was happening in the programme, as well as what power dynamics were at play and with what consequences for innovation. The evidence emanating from the study suggests a number of possibilities for consideration by future leadership development programme designers. First, the ELMD programme delivery design shows what can be done to draw participants from various levels of the schooling system, district, school and community and teach them educational leadership together in a mode that mobilizes them for change. Second, how social distance separating different levels of the education hierarchy and status consciousness may disappear gradually as people are brought together to work on tasks of mutual concern. Third, after a year of engagement with ELMD ideas and approach, the participants in the programme appeared to have started a journey of selftransformation towards becoming qualitatively different people who saw themselves as teams capable of tackling education and social problems in their schools and communities. These participants had begun to forge working networks, but the extent to which these could be characterized as knowledge ecosystems and communities of practice remains a question to explore. Fourth, that the current higher education accreditation policies and practices do not accommodate innovative learning approaches of the kind that the ELMD is developing. In this regard, the ELMD experienced difficulties in coming up with an assessment policy and practices which meet the academic as well as the practical developmental concerns of the programme. Fifth, programme instrumentalities and mandates that are put in place do not, in themselves, bring about change. The actual change comes about through the actions of human leadership capable of navigating between structural enablers and constraints.
- Full Text:
- Date Issued: 2005
The nature and potential of industrial development within the Southern African Development Community (SADC) and the facilitating role of trade liberalisation and foreign direct investment in selected countries
- Authors: Mutambara, Tsitsi Effie
- Date: 2005
- Subjects: Southern African Development Community Investments, Foreign -- Africa, Southern Free trade -- Africa, Southern Economic development -- Africa, Southern Industrialization -- Africa, Southern Industrial policy -- Africa, Southern Africa, Southern -- Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1071 , http://hdl.handle.net/10962/d1007732
- Description: To date the SADC region has managed to develop a manufacturing base but this base is still small as evidenced by its low contribution to GDP. For example, only three out of the fourteen SADC countries, viz. Mauritius, South Africa and Swaziland, had over 20 percent of their GDP originating from the manufacturing sector throughout the 1990s. Also to note is that while the manufacturing sector is quite diversified, the sector is dominated by industrial processes which are more of resource and labour-intensive in nature than those processes of scale-intensive, differentiated and science based in nature. TIle trade performance of the manufacturing sector supports these observations and as such the region is heavily dependent on imports for scale-intensive, differentiated and science based commodities. However, despite the fact that the region tends to focus more on resource- and labour-intensive manufacturing activities, products from these manufacturing activities are still significant components of manufactured goods imports into the region. Also to note is that since resource- and labour-intensive industries dominate manufacturing activities; these are the areas in which investment opportunities abound. For example, agro-based manufacturing presents most of the investment opportunities, with food processing presenting the majority of the investment opportunities followed by garments and textiles production. Mineral processing also presents significant investment opportunities. The analyses of the nature of the manufacturing sector also show that in a few SADC countries, viz. Mauritius, South Africa and Zimbabwe; scale-intensive, differentiated and science based industries also form a significant component of the industrial base implying more technologically complex manufacturing sectors. Since high technology and technologically complex manufacturing activities are limited, investment opportunities in these manufacturing sub-sectors are also limited to just a few countries However, with the SADC ITA in place, opportunities could arise for these limited technology-related manufacturing facilities to expand or engage in import substitution production so as to meet the demands of the growing regional market. It is also important to note that, while the region may not have as competitive advantage in these industries as in the resource- and labour-intensive industries, there is a need for the region to selectively identify and target such industries for priority development, a lesson SADC could learn from the East Asian NIC's took in their industrialisation strategy. The study also shows that the manufacturing sector has been a priority sector for both domestic and foreign investors. This has implications for industrial development because a strong and dynamic manufacturing sector would be developed, forming a sound basis for industrialisation as well as being able to effectively link and support all the other sectors of the economy. FDI could help the region to fully utilise the labour-intensive industries and use them as a stepping-stone to higher levels of industrial development. This is a lesson to SADC from the experiences of the East Asian NICs where while industrialisation was initiated by labour-intensive manufacturing, the countries were able to move into capital-intensive manufacturing due to FDI as it enabled the establishment of the industrial bases, thus leading to a rise in the share of manufactured exports. FDI could also help to develop the resource-intensive industries further by promoting further processing of raw materials into products of more value, thus propelling industrialisation through a resource-led industrial development programme as the current resource-intensive industries become fully utilised. The raw materials which occur in great abundance in the region's primary sector would have a ready market in the manufacturing sector where they would serve as inputs to the production of high value products. The currently smaller industrial base for scale-intensive products, differentiated and science-based manufactured products would benefit from the improved technological capabilities and managerial skills that result from FDI. Therefore, by impacting positively on manufacturing activities of both low and high MVA, FDI would thus have a facilitating role in establishing a more solid industrial base, broadening the current manufacturing base, and improving installed capacity utilisation. The study also shows that investment in productive capacity in the form of machinery and equipment is of great importance in the sampled SADC countries. Investment towards the acquisition of this capital is very important as this is directly relevant towards improving productive capacity. FDI could thus play a facilitating role by augmenting the current domestic investment in machinery and equipment. While the manufacturing sector within the region is still small and the current utilisation of installed industrial capacity is low, there is potential for further industrial growth. The current process to usher in the SADC Free Trade Area would have a facilitating role through various ways: viz. increasing the market size and enabling easier access through the reduction of tariff and non-tariff barriers, promoting regional competitiveness, improved utilisation of regional corridors, increasing opportunities for utilising identified intra-industry trade potentials, and providing opportunities for increased regional cross-border investment. Apart from the SADC FTA, the USA African Growth and Opportunity Act (AGOA) and the Cotonou Agreement will also motivate the identification and utilisation of existing and new potentials within the manufacturing sector in SADC. In order to improve the current nature of industries in the region, there is also a need to design and implement appropriate industrial policies and strategies. Such policies should consider the region's trade policies and the recently launched Regional Indicative Strategic Development Plan (RISDP) so as to complement them. The industrial policies should also address issues relating to industrial investment, technology and local technological capabilities development, human resources development, the structure and nature of industry, the competitiveness of industries, as well as facilitating the complementarities between the agricultural and manufacturing sectors. To this end therefore, instead of relying solely on individual national industrial policies, SADC is in the process of formulating a regional industrial policy and strategies which seek to promote and support sustainable industrial growth across the region, thus facilitating industrial development.
- Full Text:
- Date Issued: 2005
- Authors: Mutambara, Tsitsi Effie
- Date: 2005
- Subjects: Southern African Development Community Investments, Foreign -- Africa, Southern Free trade -- Africa, Southern Economic development -- Africa, Southern Industrialization -- Africa, Southern Industrial policy -- Africa, Southern Africa, Southern -- Economic policy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1071 , http://hdl.handle.net/10962/d1007732
- Description: To date the SADC region has managed to develop a manufacturing base but this base is still small as evidenced by its low contribution to GDP. For example, only three out of the fourteen SADC countries, viz. Mauritius, South Africa and Swaziland, had over 20 percent of their GDP originating from the manufacturing sector throughout the 1990s. Also to note is that while the manufacturing sector is quite diversified, the sector is dominated by industrial processes which are more of resource and labour-intensive in nature than those processes of scale-intensive, differentiated and science based in nature. TIle trade performance of the manufacturing sector supports these observations and as such the region is heavily dependent on imports for scale-intensive, differentiated and science based commodities. However, despite the fact that the region tends to focus more on resource- and labour-intensive manufacturing activities, products from these manufacturing activities are still significant components of manufactured goods imports into the region. Also to note is that since resource- and labour-intensive industries dominate manufacturing activities; these are the areas in which investment opportunities abound. For example, agro-based manufacturing presents most of the investment opportunities, with food processing presenting the majority of the investment opportunities followed by garments and textiles production. Mineral processing also presents significant investment opportunities. The analyses of the nature of the manufacturing sector also show that in a few SADC countries, viz. Mauritius, South Africa and Zimbabwe; scale-intensive, differentiated and science based industries also form a significant component of the industrial base implying more technologically complex manufacturing sectors. Since high technology and technologically complex manufacturing activities are limited, investment opportunities in these manufacturing sub-sectors are also limited to just a few countries However, with the SADC ITA in place, opportunities could arise for these limited technology-related manufacturing facilities to expand or engage in import substitution production so as to meet the demands of the growing regional market. It is also important to note that, while the region may not have as competitive advantage in these industries as in the resource- and labour-intensive industries, there is a need for the region to selectively identify and target such industries for priority development, a lesson SADC could learn from the East Asian NIC's took in their industrialisation strategy. The study also shows that the manufacturing sector has been a priority sector for both domestic and foreign investors. This has implications for industrial development because a strong and dynamic manufacturing sector would be developed, forming a sound basis for industrialisation as well as being able to effectively link and support all the other sectors of the economy. FDI could help the region to fully utilise the labour-intensive industries and use them as a stepping-stone to higher levels of industrial development. This is a lesson to SADC from the experiences of the East Asian NICs where while industrialisation was initiated by labour-intensive manufacturing, the countries were able to move into capital-intensive manufacturing due to FDI as it enabled the establishment of the industrial bases, thus leading to a rise in the share of manufactured exports. FDI could also help to develop the resource-intensive industries further by promoting further processing of raw materials into products of more value, thus propelling industrialisation through a resource-led industrial development programme as the current resource-intensive industries become fully utilised. The raw materials which occur in great abundance in the region's primary sector would have a ready market in the manufacturing sector where they would serve as inputs to the production of high value products. The currently smaller industrial base for scale-intensive products, differentiated and science-based manufactured products would benefit from the improved technological capabilities and managerial skills that result from FDI. Therefore, by impacting positively on manufacturing activities of both low and high MVA, FDI would thus have a facilitating role in establishing a more solid industrial base, broadening the current manufacturing base, and improving installed capacity utilisation. The study also shows that investment in productive capacity in the form of machinery and equipment is of great importance in the sampled SADC countries. Investment towards the acquisition of this capital is very important as this is directly relevant towards improving productive capacity. FDI could thus play a facilitating role by augmenting the current domestic investment in machinery and equipment. While the manufacturing sector within the region is still small and the current utilisation of installed industrial capacity is low, there is potential for further industrial growth. The current process to usher in the SADC Free Trade Area would have a facilitating role through various ways: viz. increasing the market size and enabling easier access through the reduction of tariff and non-tariff barriers, promoting regional competitiveness, improved utilisation of regional corridors, increasing opportunities for utilising identified intra-industry trade potentials, and providing opportunities for increased regional cross-border investment. Apart from the SADC FTA, the USA African Growth and Opportunity Act (AGOA) and the Cotonou Agreement will also motivate the identification and utilisation of existing and new potentials within the manufacturing sector in SADC. In order to improve the current nature of industries in the region, there is also a need to design and implement appropriate industrial policies and strategies. Such policies should consider the region's trade policies and the recently launched Regional Indicative Strategic Development Plan (RISDP) so as to complement them. The industrial policies should also address issues relating to industrial investment, technology and local technological capabilities development, human resources development, the structure and nature of industry, the competitiveness of industries, as well as facilitating the complementarities between the agricultural and manufacturing sectors. To this end therefore, instead of relying solely on individual national industrial policies, SADC is in the process of formulating a regional industrial policy and strategies which seek to promote and support sustainable industrial growth across the region, thus facilitating industrial development.
- Full Text:
- Date Issued: 2005
A commercial process development for plant food formulation using polyprotic acids from natural extracts as chelating agents
- Authors: Ndibewu, Peter Papoh
- Date: 2005
- Subjects: Chelates , Lemon juice , Liquid fertilizers
- Language: English
- Type: Thesis , Doctoral , DTech (Chemistry)
- Identifier: vital:10368 , http://hdl.handle.net/10948/153 , Chelates , Lemon juice , Liquid fertilizers
- Description: The citrus industry is one of South Africa's largest agricultural sectors in terms of export earnings with lemon fruits and juice as a trendsetter due to their high grade quality. According to growers, the Eastern Cape Province of South Africa alone produces an excess of about 10-14,000 tons of lemon juice which is presently of no economic value due to the sour taste and “bitterness”. As a result of this excess and in order to make use of the polyprotic acids naturally occurring in the lemon juice, four fertilizer nutrient mixtures are formulated, using lemon juice as base. From a conceptual scientific approach, characterization (physico-chemical and functional properties determinations) of Eureka Lemon fruit juices were undertaken, followed by smaller scale batch formulation experiments. On the basis that these lemon juice-based fertilizer mixtures are prepared following standard liquid fertilizer formulation guidelines, a field test was conducted to evaluate their potential effectiveness to influence plant growth. A growth chamber testing on tomato plants revealed high growth response (> 99.9 % certainty) potential in two of the semi-organic mixtures formulated while the organic mixture showed a relatively good growth rate as compared to the control (pure tap water). According to statistical analysis (ANOVA) comparison, two of the semi-organic mixtures performed considerably better than the two commercial samples evaluated. Potential benefits profoundly associated with these nutrient mixtures as compared to similar liquid fertilizer products on the market is that most nutrients are chelated and dissolved in solution. Also, the mixtures contain all necessary nutrients including plant growth substances required for healthier plant growth. The most important socioeconomic impact is the value addition to the technology chain in the citrus industry. The use of fluid fertilizers in significant quantities is less than twenty years old. Nevertheless, growth has been so rapid that in South Africa demand for mixed liquid fertilizer has greatly increased from 90 000 tons NPK & blended micronutrients in 1955 to more than 600 000 per annum tons today (Report 41/2003, Department of Minerals and Energy). The liquid fertilizers market is sparsely specialized with major competitors like Omnia, Kynoch and Foskor supplying more than 50 % of the market demand. Amongst the nutrient mixtures formulated, mixture one is an NPK (1-1-2) based nutrient mixture containing both secondary nutrients (0.5 % Mg & 1.0 % Ca) and seven micronutrients (0.1 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co). The composition of this mixture offers the formula a potential to be used as a general purpose (all stages of plant growth) fertilization mixture in view of its balanced composition (containing all essential plant nutrients). Mixture two contains essentially the micronutrients and in higher concentrations (0.3 % Fe, 0.3 % Cu, 0.1 % Zn, 0.2 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co) as compared to mixture one except for boron, molybdenum and cobalt. The concentration of the micronutrients contained in this mixture is adequately high which offers a potential for it to be used in supplementing nutrition in plants with critical micronutrient-deficient symptoms. Mixture three is very similar to mixture two (1.0 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 Mn, 0.05 % B, 0.0005 % Mo and 0.0005 % Co) except that the concentrations of all seven micronutrients are considerably less than those of contained in mixture two. However, the concentration of iron in this mixture is as high as 1.0 %. The mixture has a potential to be used in high iron-deficient situations. Mixture four is an organic formula with relatively low nutrient concentrations (NPK-0.02-0.02-1, 0.27 % Mg, 0.02 % Ca, 0.008 % Fe, 0.26 % Cu, 0.012 % Zn, 0.009 % Mn). Nevertheless, this mixture is appealing for organically grown crops where the use of chemicals is prohibited by standards. These lemon juice-based nutrient mixtures were further characterized and tested for stability and storability over a period of eight weeks. This study revealed no major change in the physical quality (colour, pH and “salt out” effect). The basic formulation methodology is a two-step procedure that involves filtration of the lemon juice to remove membranous materials, mixing at ambient temperature and stabilization of the nutrient mixtures. However, for the organic nutrient formula mix, filtration follows after extraction of nutrients from plant materials using the lemon juice.
- Full Text:
- Date Issued: 2005
- Authors: Ndibewu, Peter Papoh
- Date: 2005
- Subjects: Chelates , Lemon juice , Liquid fertilizers
- Language: English
- Type: Thesis , Doctoral , DTech (Chemistry)
- Identifier: vital:10368 , http://hdl.handle.net/10948/153 , Chelates , Lemon juice , Liquid fertilizers
- Description: The citrus industry is one of South Africa's largest agricultural sectors in terms of export earnings with lemon fruits and juice as a trendsetter due to their high grade quality. According to growers, the Eastern Cape Province of South Africa alone produces an excess of about 10-14,000 tons of lemon juice which is presently of no economic value due to the sour taste and “bitterness”. As a result of this excess and in order to make use of the polyprotic acids naturally occurring in the lemon juice, four fertilizer nutrient mixtures are formulated, using lemon juice as base. From a conceptual scientific approach, characterization (physico-chemical and functional properties determinations) of Eureka Lemon fruit juices were undertaken, followed by smaller scale batch formulation experiments. On the basis that these lemon juice-based fertilizer mixtures are prepared following standard liquid fertilizer formulation guidelines, a field test was conducted to evaluate their potential effectiveness to influence plant growth. A growth chamber testing on tomato plants revealed high growth response (> 99.9 % certainty) potential in two of the semi-organic mixtures formulated while the organic mixture showed a relatively good growth rate as compared to the control (pure tap water). According to statistical analysis (ANOVA) comparison, two of the semi-organic mixtures performed considerably better than the two commercial samples evaluated. Potential benefits profoundly associated with these nutrient mixtures as compared to similar liquid fertilizer products on the market is that most nutrients are chelated and dissolved in solution. Also, the mixtures contain all necessary nutrients including plant growth substances required for healthier plant growth. The most important socioeconomic impact is the value addition to the technology chain in the citrus industry. The use of fluid fertilizers in significant quantities is less than twenty years old. Nevertheless, growth has been so rapid that in South Africa demand for mixed liquid fertilizer has greatly increased from 90 000 tons NPK & blended micronutrients in 1955 to more than 600 000 per annum tons today (Report 41/2003, Department of Minerals and Energy). The liquid fertilizers market is sparsely specialized with major competitors like Omnia, Kynoch and Foskor supplying more than 50 % of the market demand. Amongst the nutrient mixtures formulated, mixture one is an NPK (1-1-2) based nutrient mixture containing both secondary nutrients (0.5 % Mg & 1.0 % Ca) and seven micronutrients (0.1 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co). The composition of this mixture offers the formula a potential to be used as a general purpose (all stages of plant growth) fertilization mixture in view of its balanced composition (containing all essential plant nutrients). Mixture two contains essentially the micronutrients and in higher concentrations (0.3 % Fe, 0.3 % Cu, 0.1 % Zn, 0.2 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co) as compared to mixture one except for boron, molybdenum and cobalt. The concentration of the micronutrients contained in this mixture is adequately high which offers a potential for it to be used in supplementing nutrition in plants with critical micronutrient-deficient symptoms. Mixture three is very similar to mixture two (1.0 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 Mn, 0.05 % B, 0.0005 % Mo and 0.0005 % Co) except that the concentrations of all seven micronutrients are considerably less than those of contained in mixture two. However, the concentration of iron in this mixture is as high as 1.0 %. The mixture has a potential to be used in high iron-deficient situations. Mixture four is an organic formula with relatively low nutrient concentrations (NPK-0.02-0.02-1, 0.27 % Mg, 0.02 % Ca, 0.008 % Fe, 0.26 % Cu, 0.012 % Zn, 0.009 % Mn). Nevertheless, this mixture is appealing for organically grown crops where the use of chemicals is prohibited by standards. These lemon juice-based nutrient mixtures were further characterized and tested for stability and storability over a period of eight weeks. This study revealed no major change in the physical quality (colour, pH and “salt out” effect). The basic formulation methodology is a two-step procedure that involves filtration of the lemon juice to remove membranous materials, mixing at ambient temperature and stabilization of the nutrient mixtures. However, for the organic nutrient formula mix, filtration follows after extraction of nutrients from plant materials using the lemon juice.
- Full Text:
- Date Issued: 2005
Virtuous living towards an African theology of wisdom in the context of the African renaissance
- Nkesiga, Reverend Solomon Basabose
- Authors: Nkesiga, Reverend Solomon Basabose
- Date: 2005
- Subjects: Wisdom -- Religious aspects , Ethics -- Africa -- Religious aspects , Black theology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8414 , http://hdl.handle.net/10948/454 , http://hdl.handle.net/10948/d1011900 , Wisdom -- Religious aspects , Ethics -- Africa -- Religious aspects , Black theology
- Description: The structure of this study is a complex inter-relationship of a variety of sources in a theological work, namely, personal experience, African social and politico-economic context, philosophical reflection, wisdom traditions and Christian theology. These sources form a coherent inter-relationship which is foundational for an African theology of wisdom. The introduction gives an overview of my moral and theological formation. This is intended to provide a perspective through which the issue of moral orientation in African context has been approached. It is therefore entitled: Moral formation and the shaping of a theological mind. The first chapter answers the question: Why is Africa in need of a wisdom theology that addresses the issue of moral regeneration? This question is posed in the broader context of the current African Renaissance debates. The links between the Italian (European) and African Renaissance indicate that moral regeneration is a crucial part of the socio-political, intellectual and economic re-birth of Africa. This “socio-historical” source gives the context and urgency of a wisdom theology. It is therefore entitled: A contextual analysis: The European and African Renaissance. The second chapter re-asserts the rise of virtue ethics as an alternative ethical theory to the predominant deontological and utilitarian traditions. This is achieved through analysing Alisdair MacIntyre’s earlier work, After Virtue: A Study in Moral Theory (1981), set in the context of Iris Murdoch and Elizabeth Anscombe, the modern initiators of a virtue ethic. This “philosophical” source gives the theoretical framework that addresses the question of moral formation. It is therefore entitled: A philosophical analysis: The rise of virtue ethics as alternative ethical theory. The third chapter is devoted to two related “wisdom” themes: Firstly, the seven traditional virtues are briefly described highlighting the virtue of wisdom as foundational. Secondly, the idea of wisdom is further developed via three wisdom traditions, namely: wisdom in the Hellenistic, Judeo-Christian and African traditions. This “sapiential” source gives this African theology of wisdom its most important building blocks. This chapter is therefore entitled: A sapiential analysis: Wisdom as foundation for virtue ethics in Africa. The last chapter brings the previous sources together under a specific theological perspective. It draws on aspects of recent African theologians’ work, notably: Kwame Gyekye and Benezet Bujo who engage with and bring together Western and African theological traditions. I answer a pertinent question, “What does such a ‘theological’ perspective entail?” I draw on Scripture and its Trinitarian tradition to demonstrate how African wisdom, reinforced by the framework of virtue theory, and developed in the context of present-day Africa by an African student of theology, has the potential to contribute to the moral transformation of Africa. This more overt “theological” source is the distinctive Christian enterprise of an African wisdom theology. The chapter title is aligned with the overall title of this study: A theological analysis: Toward an African virtue ethics? To this end, this study achieves its attempt to construct an inter-related framework from which an African theology of wisdom may emerge.
- Full Text:
- Date Issued: 2005
- Authors: Nkesiga, Reverend Solomon Basabose
- Date: 2005
- Subjects: Wisdom -- Religious aspects , Ethics -- Africa -- Religious aspects , Black theology
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8414 , http://hdl.handle.net/10948/454 , http://hdl.handle.net/10948/d1011900 , Wisdom -- Religious aspects , Ethics -- Africa -- Religious aspects , Black theology
- Description: The structure of this study is a complex inter-relationship of a variety of sources in a theological work, namely, personal experience, African social and politico-economic context, philosophical reflection, wisdom traditions and Christian theology. These sources form a coherent inter-relationship which is foundational for an African theology of wisdom. The introduction gives an overview of my moral and theological formation. This is intended to provide a perspective through which the issue of moral orientation in African context has been approached. It is therefore entitled: Moral formation and the shaping of a theological mind. The first chapter answers the question: Why is Africa in need of a wisdom theology that addresses the issue of moral regeneration? This question is posed in the broader context of the current African Renaissance debates. The links between the Italian (European) and African Renaissance indicate that moral regeneration is a crucial part of the socio-political, intellectual and economic re-birth of Africa. This “socio-historical” source gives the context and urgency of a wisdom theology. It is therefore entitled: A contextual analysis: The European and African Renaissance. The second chapter re-asserts the rise of virtue ethics as an alternative ethical theory to the predominant deontological and utilitarian traditions. This is achieved through analysing Alisdair MacIntyre’s earlier work, After Virtue: A Study in Moral Theory (1981), set in the context of Iris Murdoch and Elizabeth Anscombe, the modern initiators of a virtue ethic. This “philosophical” source gives the theoretical framework that addresses the question of moral formation. It is therefore entitled: A philosophical analysis: The rise of virtue ethics as alternative ethical theory. The third chapter is devoted to two related “wisdom” themes: Firstly, the seven traditional virtues are briefly described highlighting the virtue of wisdom as foundational. Secondly, the idea of wisdom is further developed via three wisdom traditions, namely: wisdom in the Hellenistic, Judeo-Christian and African traditions. This “sapiential” source gives this African theology of wisdom its most important building blocks. This chapter is therefore entitled: A sapiential analysis: Wisdom as foundation for virtue ethics in Africa. The last chapter brings the previous sources together under a specific theological perspective. It draws on aspects of recent African theologians’ work, notably: Kwame Gyekye and Benezet Bujo who engage with and bring together Western and African theological traditions. I answer a pertinent question, “What does such a ‘theological’ perspective entail?” I draw on Scripture and its Trinitarian tradition to demonstrate how African wisdom, reinforced by the framework of virtue theory, and developed in the context of present-day Africa by an African student of theology, has the potential to contribute to the moral transformation of Africa. This more overt “theological” source is the distinctive Christian enterprise of an African wisdom theology. The chapter title is aligned with the overall title of this study: A theological analysis: Toward an African virtue ethics? To this end, this study achieves its attempt to construct an inter-related framework from which an African theology of wisdom may emerge.
- Full Text:
- Date Issued: 2005
Synthesis and electrocatalytic properties of polymerizable metallophthalocyanines
- Authors: Obirai, Joseph Chinye
- Date: 2005
- Subjects: Phthalocyanines Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4447 , http://hdl.handle.net/10962/d1007733
- Description: The syntheses, spectral and electrochemical characterization of new family electropolymerizable pyrrole, thiophene and mercaptopyrimidin substituted metallophthalocyanine (MPc) complexes are described. Tetraamino substituted chromium and manganese phthalocyanine complexes were also synthesized and characterized. The spectral and electrochemical results are comparable to literature reports. The complexes formed stable films when deposited on electrode surfaces. The MPc films were formed by electropolymerization, drop-dry method and self-assembling. Nickel hydroxide-like electrodes were formed by electrotransformation of nickel-tetra-4- (pyrrol-1-yl)phenoxy phthalocyanine polymer films to the corresponding PcNi-O-NiPc modified electrodes in alkaline solution. The thiophene, mercaptopyrimidine functionalized MPcs and amino group containing complexes formed good self-assembled monolayers (SAMs) on gold electrode. The electrode modification processes were reproducible. The conductivities of the electrode were dependent on the surface concentrations of the complexes as a function of electropolymerization scan numbers. The electrodes showed good catalytic responses toward L-cysteine, nitrite, nitric oxide (NO), glycine, phenol and its derivative and oxygen. The results also suggest that the presence of thio groups on the ring substituents lowers the oxidation potential of Lcysteine more compared to literature values. The stability of the amperometric responses toward the various analytes is used to diagnose the applicability of the materials for electroanalytical purposes. The limits of detection for L-cysteine, nitrite, NO and glycine were in the range of ~10⁻⁷ to 10⁻⁵ mol dm⁻³.
- Full Text:
- Date Issued: 2005
- Authors: Obirai, Joseph Chinye
- Date: 2005
- Subjects: Phthalocyanines Electrochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4447 , http://hdl.handle.net/10962/d1007733
- Description: The syntheses, spectral and electrochemical characterization of new family electropolymerizable pyrrole, thiophene and mercaptopyrimidin substituted metallophthalocyanine (MPc) complexes are described. Tetraamino substituted chromium and manganese phthalocyanine complexes were also synthesized and characterized. The spectral and electrochemical results are comparable to literature reports. The complexes formed stable films when deposited on electrode surfaces. The MPc films were formed by electropolymerization, drop-dry method and self-assembling. Nickel hydroxide-like electrodes were formed by electrotransformation of nickel-tetra-4- (pyrrol-1-yl)phenoxy phthalocyanine polymer films to the corresponding PcNi-O-NiPc modified electrodes in alkaline solution. The thiophene, mercaptopyrimidine functionalized MPcs and amino group containing complexes formed good self-assembled monolayers (SAMs) on gold electrode. The electrode modification processes were reproducible. The conductivities of the electrode were dependent on the surface concentrations of the complexes as a function of electropolymerization scan numbers. The electrodes showed good catalytic responses toward L-cysteine, nitrite, nitric oxide (NO), glycine, phenol and its derivative and oxygen. The results also suggest that the presence of thio groups on the ring substituents lowers the oxidation potential of Lcysteine more compared to literature values. The stability of the amperometric responses toward the various analytes is used to diagnose the applicability of the materials for electroanalytical purposes. The limits of detection for L-cysteine, nitrite, NO and glycine were in the range of ~10⁻⁷ to 10⁻⁵ mol dm⁻³.
- Full Text:
- Date Issued: 2005
Photophysical and photochemical studies of non-transition metal phthalocyanine derivatives
- Ogunsipe, Abimbola Olukayode
- Authors: Ogunsipe, Abimbola Olukayode
- Date: 2005
- Subjects: Photochemotherapy Phthalocyanines Spectrum analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4445 , http://hdl.handle.net/10962/d1007721
- Description: A detailed photophysicochemical study of some non-transition metal (AI, Zn, Si, Ge, and Sn) metallophthalocyanine (MPc) derivatives is presented. The effects of substituents, central metal ions and solvents on the photophysical and photochemical properties are investigated and rationalized accordingly. The presence of peripheral substituents on the macrocycle enhances the yield of the triplet state. Near infra-red absorptions of the solvents reveal that solvents which absorb around 1100 nm and around 1270 nm, quench the triplet state of the MPc derivative and singlet oxygen, respectively. Although water has a high singlet oxygen quenching effect, the singlet oxygen quantum yield (Φ∆) value for sulphonated zinc phthalocyanine in water is still reasonably high at 0.48, which may provide an explanation for the efficient photosensitization by this molecule in photodynamic studies. The lowering of Φ∆ following protonation of the MPc macrocycle is attributed to the lowering of triplet energy to the level where energy transfer to ground state oxygen is no longer favourable. MPc inclusion complexes with cyclodextrins showed larger Φ∆ values when compared to the complexes before inclusion. Job's plots show that 2:1 and 4:1 (CD:MPc) complexes may be formed. Fluorescence quenching by electron donors and acceptors were analysed by StemVolmer relationship and the results used in determining fluorescence lifetimes of the complexes. Qualitative and quantitative interpretations of the interaction of sulphonated MPcs with bovine serum albumin (BSA) are provided in this thesis. 1:1 adducts were formed with BSA, but the binding feasibilities varied markedly. Spectral, photophysical and photochemical properties of the complexes are altered in the presence of BSA.
- Full Text:
- Date Issued: 2005
- Authors: Ogunsipe, Abimbola Olukayode
- Date: 2005
- Subjects: Photochemotherapy Phthalocyanines Spectrum analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4445 , http://hdl.handle.net/10962/d1007721
- Description: A detailed photophysicochemical study of some non-transition metal (AI, Zn, Si, Ge, and Sn) metallophthalocyanine (MPc) derivatives is presented. The effects of substituents, central metal ions and solvents on the photophysical and photochemical properties are investigated and rationalized accordingly. The presence of peripheral substituents on the macrocycle enhances the yield of the triplet state. Near infra-red absorptions of the solvents reveal that solvents which absorb around 1100 nm and around 1270 nm, quench the triplet state of the MPc derivative and singlet oxygen, respectively. Although water has a high singlet oxygen quenching effect, the singlet oxygen quantum yield (Φ∆) value for sulphonated zinc phthalocyanine in water is still reasonably high at 0.48, which may provide an explanation for the efficient photosensitization by this molecule in photodynamic studies. The lowering of Φ∆ following protonation of the MPc macrocycle is attributed to the lowering of triplet energy to the level where energy transfer to ground state oxygen is no longer favourable. MPc inclusion complexes with cyclodextrins showed larger Φ∆ values when compared to the complexes before inclusion. Job's plots show that 2:1 and 4:1 (CD:MPc) complexes may be formed. Fluorescence quenching by electron donors and acceptors were analysed by StemVolmer relationship and the results used in determining fluorescence lifetimes of the complexes. Qualitative and quantitative interpretations of the interaction of sulphonated MPcs with bovine serum albumin (BSA) are provided in this thesis. 1:1 adducts were formed with BSA, but the binding feasibilities varied markedly. Spectral, photophysical and photochemical properties of the complexes are altered in the presence of BSA.
- Full Text:
- Date Issued: 2005
Contending issues in South Africa's foreign policy : universalism versus economic national interest : the case of South Africa's arms sales to 'pariah states' 1994-1999
- Authors: Othieno, Timothy
- Date: 2005
- Subjects: South Africa -- Foreign relations -- 1994- South Africa -- Politics and government -- 1994- South Africa -- Foreign economic relations Arms transfers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2868 , http://hdl.handle.net/10962/d1007712
- Description: This study examines post-apartheid South African foreign policy under former President Nelson Mandela, and the apparent ambiguities that were its recurrent feature in the period from 1994 to 1999. Its focus is on the inherent irreconcilability of the economic national interests and the foreign policy principles which included the promotion of and respect for universalist principles and interests such as human rights, democracy, international peace and security. In examining South African foreign policy during this period, it would appear that the country was trapped between two competing priorities: the need to promote "universalist" principles and the need to satisfy its national economic interests. The main aim of the study is to explain how this "irreconcilability" between universalist principles and national economic interests would later create ambiguities and contradictions in South Africa's foreign policy, weaken respect for its foreign policy principles, and ultimately lead to ideological failure among politicians who employed 'short-term gain' policy decision-making in dealing with 'pariah states'. The study further demonstrates that "realist" national interests are frequently short-term, realizable and vital for a country, while universalist interests are long-term, idealistic and usually not easily realizable. It will be argued, therefore, that a country faced with making decisions about its vital national interests, will not make efforts to pursue long-term universalist interests if that choice would in any way endanger its fundamental national interests. In order to better assess this ambiguity, this thesis will provide a case study of Pretoria's arms sales to 'pariah states' during the period. The purpose of this study is not to attempt to explain all of the issues around post-apartheid foreign policymaking, or even to argue whether the sale of arms to 'pariah states' was 'politically incorrect', but to provide a 'piece of the puzzle' which might explain how the social and economic situation may have compelled Pretoria to sell arms when these actions disregarded universalist principles of foreign policy. The conclusion seems to confirm the realist view that universal values and principles can be regarded only when they are in harmony with a state's perceived self-interests.
- Full Text:
- Date Issued: 2005
- Authors: Othieno, Timothy
- Date: 2005
- Subjects: South Africa -- Foreign relations -- 1994- South Africa -- Politics and government -- 1994- South Africa -- Foreign economic relations Arms transfers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2868 , http://hdl.handle.net/10962/d1007712
- Description: This study examines post-apartheid South African foreign policy under former President Nelson Mandela, and the apparent ambiguities that were its recurrent feature in the period from 1994 to 1999. Its focus is on the inherent irreconcilability of the economic national interests and the foreign policy principles which included the promotion of and respect for universalist principles and interests such as human rights, democracy, international peace and security. In examining South African foreign policy during this period, it would appear that the country was trapped between two competing priorities: the need to promote "universalist" principles and the need to satisfy its national economic interests. The main aim of the study is to explain how this "irreconcilability" between universalist principles and national economic interests would later create ambiguities and contradictions in South Africa's foreign policy, weaken respect for its foreign policy principles, and ultimately lead to ideological failure among politicians who employed 'short-term gain' policy decision-making in dealing with 'pariah states'. The study further demonstrates that "realist" national interests are frequently short-term, realizable and vital for a country, while universalist interests are long-term, idealistic and usually not easily realizable. It will be argued, therefore, that a country faced with making decisions about its vital national interests, will not make efforts to pursue long-term universalist interests if that choice would in any way endanger its fundamental national interests. In order to better assess this ambiguity, this thesis will provide a case study of Pretoria's arms sales to 'pariah states' during the period. The purpose of this study is not to attempt to explain all of the issues around post-apartheid foreign policymaking, or even to argue whether the sale of arms to 'pariah states' was 'politically incorrect', but to provide a 'piece of the puzzle' which might explain how the social and economic situation may have compelled Pretoria to sell arms when these actions disregarded universalist principles of foreign policy. The conclusion seems to confirm the realist view that universal values and principles can be regarded only when they are in harmony with a state's perceived self-interests.
- Full Text:
- Date Issued: 2005
The status and natural history of pygmy (Kogia breviceps) and dwarf (K. sima) sperm whales off Southern Africa
- Authors: Plön, Stephanie
- Date: 2005
- Subjects: Pygmy sperm whale Dwarf sperm whale Population genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5772 , http://hdl.handle.net/10962/d1005460
- Description: For the present study 106 strandings of Kogia breviceps and 85 strandings of K. sima along the South African coastline between 1880 and 1995 were analysed in order to examine the age and growth, male and female reproduction, diet, stranding patterns, and population genetic structure of both species. Length and weight at birth were about 120cm and 53kg for K. breviceps and about 103cm and 14kg for K. sima. Von Bertalanffy growth curves were fitted to the data and indicated that physical maturity was reached at around 15 years in both sexes of K. breviceps and at 13 years in female and 15 years in male K. sima. Asymptotic length was reached at 306.0 and 286.1cm in female and male K. breviceps and 249.14 and 263.75cm in female and male K. sima, respectively. Maximum ages were16 years for male K. breviceps and 23 years for females and 17 years for male K. sima and 22 years for females. Reversed sexual size dimorphism was suggested for K. breviceps, while in K. sima males were larger than females. Attainment of sexual maturity in males occurred at between 2.5 and 5 years of age in K. breviceps and 2.6 and 3 years in K. sima, corresponding to 241-242cm and 197cm body length, respectively. The maximum combined testis weight comprised 1.04% and 2.00% for K. breviceps and K. sima, respectively, and a polygynous mating system with a roving male strategy was proposed for both species. The sperm morphology for both Kogia species was described and is characterised by 20-25 spherical mitochondria arranged in rows around the midpiece. Attainment of sexual maturity in females occurred at 5 years in both Kogia species, and at 262cm and 215cm body length in K. breviceps and K. sima, respectively. The ovulation rates were 0.9 and 0.7 per year for K. breviceps and K. sima, respectively. In K. breviceps conceptions occurred from April to September and births from March to August, while in K. sima both conceptions and births occurred from December to March. Annual reproduction and a post-partum oestrus was suggested for both Kogia species. The diet of K. breviceps comprised 50 different cephalopod species from 22 families and 17 other prey species, while K. sima fed on 32 cephalopod species from 17 families and six others. Although niche overlap indices between the two species and between groups within each species were high, some differences in diet could be determined, which allow these two sympatrically occurring species to share the same ecological niche off the coast of Southern Africa. An analysis of the stranding patterns revealed that K. sima has a closer affinity to the Agulhas current and to higher water temperatures than K. breviceps, which is supported by differences in the size of the appendages between the two species. The population genetic analysis revealed a high haplotype and nucleotide diversity for K. breviceps in the Southern hemisphere, but a lack of significant phylogeographic structure, indicating substantial gene flow among populations and inhibiting genetic differentiation of local populations, although the South African population was somewhat isolated from others in the Southern Hemisphere. In contrast the data on the phylogeographic structure of K. sima were somewhat restrictive as the majority of the samples originated from South Africa. Nevertheless, both nucleotide and haplotype diversities were markedly lower than in K. breviceps and more similar to those for other small cetacean populations, suggesting a smaller population size for K. sima than for K. breviceps. Although both Kogia species belong to the medium to larger-sized odontocetes their life histories are located near the fast end of the slow-fast continuum of life histories of marine mammals, indicating high mortality rates. The “false-gill” marking and the ability to squirt ink are thought to reflect adaptations to predator mimicry and avoidance.
- Full Text:
- Date Issued: 2005
- Authors: Plön, Stephanie
- Date: 2005
- Subjects: Pygmy sperm whale Dwarf sperm whale Population genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5772 , http://hdl.handle.net/10962/d1005460
- Description: For the present study 106 strandings of Kogia breviceps and 85 strandings of K. sima along the South African coastline between 1880 and 1995 were analysed in order to examine the age and growth, male and female reproduction, diet, stranding patterns, and population genetic structure of both species. Length and weight at birth were about 120cm and 53kg for K. breviceps and about 103cm and 14kg for K. sima. Von Bertalanffy growth curves were fitted to the data and indicated that physical maturity was reached at around 15 years in both sexes of K. breviceps and at 13 years in female and 15 years in male K. sima. Asymptotic length was reached at 306.0 and 286.1cm in female and male K. breviceps and 249.14 and 263.75cm in female and male K. sima, respectively. Maximum ages were16 years for male K. breviceps and 23 years for females and 17 years for male K. sima and 22 years for females. Reversed sexual size dimorphism was suggested for K. breviceps, while in K. sima males were larger than females. Attainment of sexual maturity in males occurred at between 2.5 and 5 years of age in K. breviceps and 2.6 and 3 years in K. sima, corresponding to 241-242cm and 197cm body length, respectively. The maximum combined testis weight comprised 1.04% and 2.00% for K. breviceps and K. sima, respectively, and a polygynous mating system with a roving male strategy was proposed for both species. The sperm morphology for both Kogia species was described and is characterised by 20-25 spherical mitochondria arranged in rows around the midpiece. Attainment of sexual maturity in females occurred at 5 years in both Kogia species, and at 262cm and 215cm body length in K. breviceps and K. sima, respectively. The ovulation rates were 0.9 and 0.7 per year for K. breviceps and K. sima, respectively. In K. breviceps conceptions occurred from April to September and births from March to August, while in K. sima both conceptions and births occurred from December to March. Annual reproduction and a post-partum oestrus was suggested for both Kogia species. The diet of K. breviceps comprised 50 different cephalopod species from 22 families and 17 other prey species, while K. sima fed on 32 cephalopod species from 17 families and six others. Although niche overlap indices between the two species and between groups within each species were high, some differences in diet could be determined, which allow these two sympatrically occurring species to share the same ecological niche off the coast of Southern Africa. An analysis of the stranding patterns revealed that K. sima has a closer affinity to the Agulhas current and to higher water temperatures than K. breviceps, which is supported by differences in the size of the appendages between the two species. The population genetic analysis revealed a high haplotype and nucleotide diversity for K. breviceps in the Southern hemisphere, but a lack of significant phylogeographic structure, indicating substantial gene flow among populations and inhibiting genetic differentiation of local populations, although the South African population was somewhat isolated from others in the Southern Hemisphere. In contrast the data on the phylogeographic structure of K. sima were somewhat restrictive as the majority of the samples originated from South Africa. Nevertheless, both nucleotide and haplotype diversities were markedly lower than in K. breviceps and more similar to those for other small cetacean populations, suggesting a smaller population size for K. sima than for K. breviceps. Although both Kogia species belong to the medium to larger-sized odontocetes their life histories are located near the fast end of the slow-fast continuum of life histories of marine mammals, indicating high mortality rates. The “false-gill” marking and the ability to squirt ink are thought to reflect adaptations to predator mimicry and avoidance.
- Full Text:
- Date Issued: 2005
The early proterozoic Makganyene glacial event in South Africa : its implication in sequence stratigraphy interpretations, paleoenvironmental conditions and iron and manganese ore deposition
- Authors: Polteau, Stéphane
- Date: 2005
- Subjects: Geology, Stratigraphic -- South Africa -- Northern Cape Geochemistry -- South Africa -- Northern Cape Paleogeography -- South Africa -- Northern Cape Petrology -- South Africa -- Northern Cape Ore deposits -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5039 , http://hdl.handle.net/10962/d1007612
- Description: The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.
- Full Text:
- Date Issued: 2005
- Authors: Polteau, Stéphane
- Date: 2005
- Subjects: Geology, Stratigraphic -- South Africa -- Northern Cape Geochemistry -- South Africa -- Northern Cape Paleogeography -- South Africa -- Northern Cape Petrology -- South Africa -- Northern Cape Ore deposits -- South Africa -- Northern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5039 , http://hdl.handle.net/10962/d1007612
- Description: The Makganyene Formation forms the base of the Postmasburg Group in the Transvaal Supergroup in the Griqualand West Basin. It consists of diamictites, sandstones, banded iron-formations (BIFs), shales, siltstones and carbonates. It is generally accepted that the Makganyene Formation rests on an erosive regional unconformity throughout the Northern Cape Province. However this study demonstrates that this stratigraphic relationship is not universal, and conformable contacts have been observed. One of the principal aims of this study is to identify the nature of the Makganyene basal contact throughout the Griqualand West Basin. Intensive fieldwork was carried out from Prieska in the south, to Danielskuil in the north. In the Sishen and Hotazel areas, only borehole material was available to assess the stratigraphy. The Griquatown Fault Zone delimits the boundary between the deep basin and platform facies. The Koegas Subgroup is only present south of the Griquatown Fault Zone, where it pinches out. However, the transition Griquatown BIFs-Koegas Subgroup occurs in lacustrine deposits on the Ghaap platform (Beukes, 1983). The Griquatown Fault Zone represents the edge of the basin, which corresponds to a hinge rather than a fault zone. The Makganyene Formation rests with a conformable contact on the Koegas Subgroup south of the Griquatown Hinge Zone, and north of it the Makganyene Formation lies unconformably on the Asbestos Hills Subgroup. The Makganyene Formation displays lateral facies changes that reflect the paleogeography of the Griqualand West Basin, and the development of ice sheets/shelves. The Ghaap platform is characterised by coarse immature sand interbedded with the diamictites. The clasts in this area contain local Asbestos Hills material and no dropstones are present. Such settings are typical of sediments that are being deposited below a grounded ice mass. At the Griquatown Hinge Zone, the sandstone lenses are smaller, and the clasts consist of chert, of which a great number are striated and faceted. In the Matsap area, the presence of dropstones is strong evidence for the presence of a floating ice shelf that released its material by basal melting. Further south, the Makganyene Formation contains stromatolitic bioherms that only form if clastic contamination is minimal and therefore the ice that transported the detritus to the basin did not extend far into open sea conditions. The base of the Hotazel Formation also contains diamictite levels. Dropstones have been identified, implying a glacial origin. The Hotazel diamictites are interbedded with hyaloclastites and BIFs. The Makganyene glacial event, therefore, was not restricted to the Makganyene Formation, but also included the Ongeluk Formation, through to the base of the Hotazel Formation. Petrographic studies of the Makganyene Formation and the base of the Hotazel Formation reveal mineral assemblages that are diagnostic of early to late diagenetic crystallisation and of low-grade metamorphism not exceeding the very low green-schist facies. The facies identified display the same sense of basin deepening, from shallow high-energy Hotazel area on the Ghaap platform, to the deep basin in the Matsap area. Whole-rock geochemical analyses reveal that the elemental composition of the Makganyene Formation is very similar to that of the Asbestos Hills BIFs, which were the most important source of clastic detritus for the Makganyene Formation. However, minor amounts of carbonates of the Campbellrand Subgroup, as well as a felsic crustal input from the Archean granitoid basement, made contributions. On the Ghaap platform, the Makganyene diamictite is enriched in iron, calcium, and magnesium, while in the deeper parts of the basin the diamictites are enriched in detrital elements, such as titanium and aluminium, which occur in the fine clay component. The Hotazel diamictite displays a distinct mafic volcanic input, related to the extrusion of the Ongeluk basaltic andesites, which was incorporated in the glacial sediments. Sequence stratigraphy is based on the recognition of contacts separating the different systems tracts that compose a depositional sequence. However, because the basal contact of the Makganyene Formation has not been properly identified in previous work, no correct model has been proposed so far. Therefore correlations between the Griqualand West and the Transvaal basins, based on lithostratigraphic similarities and extrapolations of unconformities, have to be reviewed, especially since the publication of new radiometric ages contradict all previously proposed correlations. It is proposed here that the Transvaal Supergroup in the Griqualand West Basin represents a continuous depositional event that lasted about 200 Ma. The Makganyene glacial event occurred during changing conditions in the chemistries of the atmosphere and ocean, and in the continental configuration. A Snowball Earth event has been proposed as the causative process of such paleoenvironmental changes. However, evidence presented here of less dramatic glacial conditions, with areas of ice-free waters, implies an alternative to the Snowball Earth event. The paleoenvironmental changes are thought to represent a transition from an anaerobic to aerobic atmosphere, that was responsible for the global cooling of the surface of the Earth, Such a glacial event may have aided in the large-scale precipitation of iron and manganese in areas of intense upwellings.
- Full Text:
- Date Issued: 2005
Supervision : a Foucaultian exploration of institutional and interpersonal power relations between postgraduate supervisors, their students and the university domain
- Authors: Rau, Asta
- Date: 2005
- Subjects: Foucault, Michel, 1926-1984 -- Methodology Foucault, Michel, 1926-1984 -- Criticism and interpretation Graduate students -- Supervision of Dissertations, Academic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1786 , http://hdl.handle.net/10962/d1003671
- Description: Supervision is widely acknowledged as influencing the quality of postgraduate theses, and by association, of postgraduates. Despite this, publications on conducting research offer far less guidance on managing the supervision relationship than on the practicalities of producing a thesis. In-depth, qualitative supervision studies are few and fewer still examine power in the supervision relationship. Michel Foucault’s insights are used to explore the question: How do postgraduate supervisors and their Master’s students experience the supervision relationship and how are the dynamics of interpersonal and institutional power implicated in these relationships? Foucault argues that power relations always involve resistances; these function primarily through institutionalized discourses to produce different forms of knowledge, one form of which is identity or subjectivity. Accordingly, power relations are explored in terms of thesis-as-product, person-as-product and the impact of both on the mediation of knowledge in the educational domain. Four institutionalized discourses in the university domain are examined: · Commercial educational management discourse: targets academics through issues of quality assurance, throughput, publication, research productivity and funding. · Anarchic educational leadership discourse: integrates quantum principles with commercial demands, change management strategies and meaningful participation. · Humanistic discourse: favours a pastoral ethic and is person-centered. · Holistic discourse: cultivates ecological sensibility and values the interconnectedness of all aspects of being-in-the-world. Data collected in sixteen semi-structured interviews with three matched supervisor-student pairs selected from the humanities and education faculties of one South African university, are presented as case studies. Data analysis combines grounded theory techniques with selected aspects of Foucault’s methods. A conceptual model is devised to analyse how participants use resistance strategies to interface their autonomy and dependency with their expectations, abilities, and professional and pastoral care. The research yields rich data in which several thematic correlations in interpersonal and institutional power dynamics are grounded. These include: the significance of supervisor-student matching; links between expectations, abilities, the way participants negotiate power and the quality of professional and pastoral care they experience; the benefit of personal affinity to thesis-as-product and person-as-product; and the impact of commercial demands on participants’ power relations. Participants tend to reproduce the discourses in which they are embedded and adopt or adapt aspects of contesting discourses to this end. Potential avenues are identified for improving supervision practice and for further research.
- Full Text:
- Date Issued: 2005
- Authors: Rau, Asta
- Date: 2005
- Subjects: Foucault, Michel, 1926-1984 -- Methodology Foucault, Michel, 1926-1984 -- Criticism and interpretation Graduate students -- Supervision of Dissertations, Academic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1786 , http://hdl.handle.net/10962/d1003671
- Description: Supervision is widely acknowledged as influencing the quality of postgraduate theses, and by association, of postgraduates. Despite this, publications on conducting research offer far less guidance on managing the supervision relationship than on the practicalities of producing a thesis. In-depth, qualitative supervision studies are few and fewer still examine power in the supervision relationship. Michel Foucault’s insights are used to explore the question: How do postgraduate supervisors and their Master’s students experience the supervision relationship and how are the dynamics of interpersonal and institutional power implicated in these relationships? Foucault argues that power relations always involve resistances; these function primarily through institutionalized discourses to produce different forms of knowledge, one form of which is identity or subjectivity. Accordingly, power relations are explored in terms of thesis-as-product, person-as-product and the impact of both on the mediation of knowledge in the educational domain. Four institutionalized discourses in the university domain are examined: · Commercial educational management discourse: targets academics through issues of quality assurance, throughput, publication, research productivity and funding. · Anarchic educational leadership discourse: integrates quantum principles with commercial demands, change management strategies and meaningful participation. · Humanistic discourse: favours a pastoral ethic and is person-centered. · Holistic discourse: cultivates ecological sensibility and values the interconnectedness of all aspects of being-in-the-world. Data collected in sixteen semi-structured interviews with three matched supervisor-student pairs selected from the humanities and education faculties of one South African university, are presented as case studies. Data analysis combines grounded theory techniques with selected aspects of Foucault’s methods. A conceptual model is devised to analyse how participants use resistance strategies to interface their autonomy and dependency with their expectations, abilities, and professional and pastoral care. The research yields rich data in which several thematic correlations in interpersonal and institutional power dynamics are grounded. These include: the significance of supervisor-student matching; links between expectations, abilities, the way participants negotiate power and the quality of professional and pastoral care they experience; the benefit of personal affinity to thesis-as-product and person-as-product; and the impact of commercial demands on participants’ power relations. Participants tend to reproduce the discourses in which they are embedded and adopt or adapt aspects of contesting discourses to this end. Potential avenues are identified for improving supervision practice and for further research.
- Full Text:
- Date Issued: 2005
The development of an electrochemical process for the production of para-substituted di-hydroxy benzenes
- Authors: Rautenbach, Daniel
- Date: 2005
- Subjects: Phenol , Benzene
- Language: English
- Type: Thesis , Doctoral , DTech (Science)
- Identifier: vital:10367 , http://hdl.handle.net/10948/159 , Phenol , Benzene
- Description: The project was concerned with the investigation of the electrochemical oxidation of various phenols, and to develop a viable reaction system for the production of the respective hydroquinones. Current production routes utilizing phenol as starting material have the limitations of using large amounts of acids, having to be stopped at low conversions and producing a mixture of the hydroquinones and catechols. Of the possible routes to the respective hydroquinones from the various phenols, the electrochemical oxidation of these phenols offers commercial and environmental advantages and hence formed the theme of the investigation. The synthetic possibilities proved to be more prevalent in a system when the electrochemical oxidation of these phenols was performed in an aqueous medium utilizing an organic co-solvent. Results obtained during this investigation made it possible to make certain predications about the mechanism taking place. This was found to depend on the anode material used for the oxidation. The results showed that the process developed for the electrochemical oxidation of these phenols, yields mainly the para-isomers of the respective hydroquinones and benzoquinones in good yields and selectivities, with fair current efficiencies and good mass balances at high conversions. For example: * Phenol (batch) 8 F: 345% current efficiency, 70% hydroquinone, 6% catechol, 9% benzoquinone, 9% phenol and 94 mass balance. * 2-Tert-butylphenol (flow) 10 F: 37% current efficiency, 65% hydroquinone, 33% benzoquinone, 2% phenol and 100% mass balance. * 2,6-Di-tert-butylphenol (flow) 11 F: 23% current efficiency, 92 % hydroquinone, 6% benzoquinone, 1% phenol and 99% mass balance. The developed electrochemical oxidation system offers the following advantages over previous and current methods: simplified isolation and extraction procedures, smaller amounts of acid usage, reasonably selective synthesis of the para-isomer and a less corrosive system all at high conversions.
- Full Text:
- Date Issued: 2005
- Authors: Rautenbach, Daniel
- Date: 2005
- Subjects: Phenol , Benzene
- Language: English
- Type: Thesis , Doctoral , DTech (Science)
- Identifier: vital:10367 , http://hdl.handle.net/10948/159 , Phenol , Benzene
- Description: The project was concerned with the investigation of the electrochemical oxidation of various phenols, and to develop a viable reaction system for the production of the respective hydroquinones. Current production routes utilizing phenol as starting material have the limitations of using large amounts of acids, having to be stopped at low conversions and producing a mixture of the hydroquinones and catechols. Of the possible routes to the respective hydroquinones from the various phenols, the electrochemical oxidation of these phenols offers commercial and environmental advantages and hence formed the theme of the investigation. The synthetic possibilities proved to be more prevalent in a system when the electrochemical oxidation of these phenols was performed in an aqueous medium utilizing an organic co-solvent. Results obtained during this investigation made it possible to make certain predications about the mechanism taking place. This was found to depend on the anode material used for the oxidation. The results showed that the process developed for the electrochemical oxidation of these phenols, yields mainly the para-isomers of the respective hydroquinones and benzoquinones in good yields and selectivities, with fair current efficiencies and good mass balances at high conversions. For example: * Phenol (batch) 8 F: 345% current efficiency, 70% hydroquinone, 6% catechol, 9% benzoquinone, 9% phenol and 94 mass balance. * 2-Tert-butylphenol (flow) 10 F: 37% current efficiency, 65% hydroquinone, 33% benzoquinone, 2% phenol and 100% mass balance. * 2,6-Di-tert-butylphenol (flow) 11 F: 23% current efficiency, 92 % hydroquinone, 6% benzoquinone, 1% phenol and 99% mass balance. The developed electrochemical oxidation system offers the following advantages over previous and current methods: simplified isolation and extraction procedures, smaller amounts of acid usage, reasonably selective synthesis of the para-isomer and a less corrosive system all at high conversions.
- Full Text:
- Date Issued: 2005
Enabling reflexivity and the development of reflexive competence within course processes: a case study of an environmental education professional development course
- Authors: Raven, Glenda C
- Date: 2005
- Subjects: Rhodes University / Gold Fields Course in Environmental Education Environmental education -- Research -- South Africa Environmental education -- South Africa -- Curricula Competency-based education -- South Africa Education and state -- South Africa Education -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1507 , http://hdl.handle.net/10962/d1003389
- Description: This research was undertaken in the context of socio-economic transformation in South Africa, and more specifically, in the context of change in education policy. To support socio-economic transformation in South Africa after the first democratic elections in 1994, a competence-based National Qualifications Framework (NQF) was introduced in 1995. In responding to the particular socio-historical context of South Africa, the South African NQF is underpinned by the notion of applied competence, integrating practical, foundational and reflexive competence, which is the key and distinguishing feature of this competence-based framework. In this context of transformation, the research was aimed at an in-depth exploration of the notion of reflexivity and reflexive competence, and course processes that enable its development, with a view to providing curriculum development insights for learning programme development in the competence-based NQF, more broadly, and environmental education professional development programmes, more specifically. To enable these aims, the research was undertaken in the context of the Rhodes University / Gold Fields Participatory Course in Environmental Education (RU/GF course), as a case example of a professional development course that aims to develop critically reflexive practitioners. Within an interpretivist orientation, a multiple-embedded case study approach was used to gain insight into the relationship between course processes, reflexivity and the development of reflexive competence to clarify and provide a critical perspective on how competence develops in the context of the course. Data was collected over a period of one year using observation, interviewing and document analysis as the primary data collection techniques. Data was analysed through various phases and layers to inform data generation and the synthesising of data for further interpretation. Through the literature review undertaken within the study, various significant insights emerged around the notion of reflexivity and reflexive competence. Firstly, there appears to be a need to distinguish between reflexivity as social processes of change (social actions and interactions within social systems, structures and processes) and reflexive competence (a range of integrative elements of competence) that provides the evidence of an engagement within social processes of change. The second key insight emerging is the significance of social structure in shaping participation in reflexive processes, thus emphasising the duality of structure as both the medium for, and outcome of reflexive social actions and interactions and so challenges the deterministic conception of social structure. Further, the significance of an epistemologically framed notion of reflexivity and reflexive competence emerged, in the context of responding to the complex and uncertain quality of socio-ecological risks and in supporting change in context. Reflexivity, distinguished from processes of critical reflection, foregrounds a critical exploration of both knowledge and unawareness. As such a reinterpretation of reflexive competence is offered as a process of potential challenge to dominant and reigning forms of reasoning (knowledge frameworks) and consequent principles of ordering. Through this reframing of reflexive competence, the potential exists to destabilise dominant forms of reasoning and principles of ordering to create a broader scope of possibilities for action and change in context. This reframing of reflexive competence in the context of transformation in South Africa has critical implications for engaging within processes of learning programme design in the NQF to support an engagement within reflexive processes of change and the development of a range of integrative elements of reflexive competence. In this light, the study attempts to make the following contribution to curriculum deliberations within the context of environmental education and the NQF in relation to reflexivity, reflexive competence and change: ♦ Reflexivity is conceptualised as social processes of change with reflexive competence providing evidence of engagement within these social processes of change; ♦ An epistemologically framed conception of reflexivity and reflexive competence recognises how rules of reason and the ordering of the ‘reasonable’ person come to shape social life; and so ♦ Change is conceptualised as ruptures and breaks in dominant knowledge frames and the power relations embedded in these; ♦ Unawareness emerges as a key dimension within reflexive environmental education processes in responding to the unpredictable and uncertain nature of risks; ♦ An epistemological framing of reflexivity and reflexive competence highlights the need to develop open processes of learning to support the critical exploration of knowledge and unawareness; and ♦ Within this framing of reflexivity and reflexive competence, the difficulty emerges in specifically predefining reflexive competence to inform standard setting processes within a context of intended change. In framing data within this emerging conception of reflexivity and reflexive competence, a review of course processes highlighted potential areas for reorienting the RU/GF course to support change in context, for which I make specific recommendations. Drawing on the review of course processes in the RU/GF course, and in light of the reframing of reflexivity and reflexive competence, I further offer summative discussions as ‘possible implications’ for learning programme design in the South African competence-based NQF, broadly and environmental education professional development programmes in this framework, more specifically.
- Full Text:
- Date Issued: 2005
- Authors: Raven, Glenda C
- Date: 2005
- Subjects: Rhodes University / Gold Fields Course in Environmental Education Environmental education -- Research -- South Africa Environmental education -- South Africa -- Curricula Competency-based education -- South Africa Education and state -- South Africa Education -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1507 , http://hdl.handle.net/10962/d1003389
- Description: This research was undertaken in the context of socio-economic transformation in South Africa, and more specifically, in the context of change in education policy. To support socio-economic transformation in South Africa after the first democratic elections in 1994, a competence-based National Qualifications Framework (NQF) was introduced in 1995. In responding to the particular socio-historical context of South Africa, the South African NQF is underpinned by the notion of applied competence, integrating practical, foundational and reflexive competence, which is the key and distinguishing feature of this competence-based framework. In this context of transformation, the research was aimed at an in-depth exploration of the notion of reflexivity and reflexive competence, and course processes that enable its development, with a view to providing curriculum development insights for learning programme development in the competence-based NQF, more broadly, and environmental education professional development programmes, more specifically. To enable these aims, the research was undertaken in the context of the Rhodes University / Gold Fields Participatory Course in Environmental Education (RU/GF course), as a case example of a professional development course that aims to develop critically reflexive practitioners. Within an interpretivist orientation, a multiple-embedded case study approach was used to gain insight into the relationship between course processes, reflexivity and the development of reflexive competence to clarify and provide a critical perspective on how competence develops in the context of the course. Data was collected over a period of one year using observation, interviewing and document analysis as the primary data collection techniques. Data was analysed through various phases and layers to inform data generation and the synthesising of data for further interpretation. Through the literature review undertaken within the study, various significant insights emerged around the notion of reflexivity and reflexive competence. Firstly, there appears to be a need to distinguish between reflexivity as social processes of change (social actions and interactions within social systems, structures and processes) and reflexive competence (a range of integrative elements of competence) that provides the evidence of an engagement within social processes of change. The second key insight emerging is the significance of social structure in shaping participation in reflexive processes, thus emphasising the duality of structure as both the medium for, and outcome of reflexive social actions and interactions and so challenges the deterministic conception of social structure. Further, the significance of an epistemologically framed notion of reflexivity and reflexive competence emerged, in the context of responding to the complex and uncertain quality of socio-ecological risks and in supporting change in context. Reflexivity, distinguished from processes of critical reflection, foregrounds a critical exploration of both knowledge and unawareness. As such a reinterpretation of reflexive competence is offered as a process of potential challenge to dominant and reigning forms of reasoning (knowledge frameworks) and consequent principles of ordering. Through this reframing of reflexive competence, the potential exists to destabilise dominant forms of reasoning and principles of ordering to create a broader scope of possibilities for action and change in context. This reframing of reflexive competence in the context of transformation in South Africa has critical implications for engaging within processes of learning programme design in the NQF to support an engagement within reflexive processes of change and the development of a range of integrative elements of reflexive competence. In this light, the study attempts to make the following contribution to curriculum deliberations within the context of environmental education and the NQF in relation to reflexivity, reflexive competence and change: ♦ Reflexivity is conceptualised as social processes of change with reflexive competence providing evidence of engagement within these social processes of change; ♦ An epistemologically framed conception of reflexivity and reflexive competence recognises how rules of reason and the ordering of the ‘reasonable’ person come to shape social life; and so ♦ Change is conceptualised as ruptures and breaks in dominant knowledge frames and the power relations embedded in these; ♦ Unawareness emerges as a key dimension within reflexive environmental education processes in responding to the unpredictable and uncertain nature of risks; ♦ An epistemological framing of reflexivity and reflexive competence highlights the need to develop open processes of learning to support the critical exploration of knowledge and unawareness; and ♦ Within this framing of reflexivity and reflexive competence, the difficulty emerges in specifically predefining reflexive competence to inform standard setting processes within a context of intended change. In framing data within this emerging conception of reflexivity and reflexive competence, a review of course processes highlighted potential areas for reorienting the RU/GF course to support change in context, for which I make specific recommendations. Drawing on the review of course processes in the RU/GF course, and in light of the reframing of reflexivity and reflexive competence, I further offer summative discussions as ‘possible implications’ for learning programme design in the South African competence-based NQF, broadly and environmental education professional development programmes in this framework, more specifically.
- Full Text:
- Date Issued: 2005
The degradation of lignocellulose in a biologically-generated sulphidic environment
- Authors: Roman, Henry James
- Date: 2005
- Subjects: Lignocellulose Sulfides Lignin Lignocellulose -- Biodegradation Mines and mineral resources -- Waste disposal Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3997 , http://hdl.handle.net/10962/d1004057
- Description: South Africa is renowned for its mining industry. The period over which the polluted waters from the existing and abandoned mines will require treatment has driven research into the development of passive treatment systems. These waters are characterised by a low pH, high concentrations of heavy metals, high levels of sulphate salts and low concentrations of organic material. The biological treatment of these waters has been a subject of increasing focus as an alternative to physicochemical treatment. The utilisation of lignocellulose as a carbon source has been restricted by the amount of reducing equivalents available within the lignocellulose matrix. After a few months of near 100% sulphate reduction, it was found that although there was a large fraction of lignin and cellulose remaining, sulphate reduction was reduced to less than 20%. The present study demonstrated that lignocellulose can be utilised as a carbon source for sulphate reduction. It was established that lignocellulose degradation was enhanced under biosulphidogenic conditions and that lignin could be degraded by a sulphate reducing microbial consortium. It was established using lignin model compounds synthesized in our laboratory, that the bonds within the lignin polymer can be cleaved within the sulphidic environment. The presence of cellulolytic enzymes, using CMCase as a marker enzyme, was detected within the sulphate reducing microbial consortium. Based on the results obtained a descriptive model was formulated for the degradation of lignocellulose under biosulphidogenic conditions. It was determined that the initial reduction in sulphate observed using lignocellulose as a carbon source was due to the easily extractable components. The degradation of which resulted in the production of sulphide, which aided in the degradation of lignin, allowing greater access to cellulose. Once the easily extractable material is exhausted, the cycle is halted, unless the sulphide production can be maintained. This is the focus of an ongoing project, testing the hypothesis that an easy to assimilate carbon source added after exhaustion of the easily extractable material, can maintain the sulphide production.
- Full Text:
- Date Issued: 2005
- Authors: Roman, Henry James
- Date: 2005
- Subjects: Lignocellulose Sulfides Lignin Lignocellulose -- Biodegradation Mines and mineral resources -- Waste disposal Acid mine drainage
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3997 , http://hdl.handle.net/10962/d1004057
- Description: South Africa is renowned for its mining industry. The period over which the polluted waters from the existing and abandoned mines will require treatment has driven research into the development of passive treatment systems. These waters are characterised by a low pH, high concentrations of heavy metals, high levels of sulphate salts and low concentrations of organic material. The biological treatment of these waters has been a subject of increasing focus as an alternative to physicochemical treatment. The utilisation of lignocellulose as a carbon source has been restricted by the amount of reducing equivalents available within the lignocellulose matrix. After a few months of near 100% sulphate reduction, it was found that although there was a large fraction of lignin and cellulose remaining, sulphate reduction was reduced to less than 20%. The present study demonstrated that lignocellulose can be utilised as a carbon source for sulphate reduction. It was established that lignocellulose degradation was enhanced under biosulphidogenic conditions and that lignin could be degraded by a sulphate reducing microbial consortium. It was established using lignin model compounds synthesized in our laboratory, that the bonds within the lignin polymer can be cleaved within the sulphidic environment. The presence of cellulolytic enzymes, using CMCase as a marker enzyme, was detected within the sulphate reducing microbial consortium. Based on the results obtained a descriptive model was formulated for the degradation of lignocellulose under biosulphidogenic conditions. It was determined that the initial reduction in sulphate observed using lignocellulose as a carbon source was due to the easily extractable components. The degradation of which resulted in the production of sulphide, which aided in the degradation of lignin, allowing greater access to cellulose. Once the easily extractable material is exhausted, the cycle is halted, unless the sulphide production can be maintained. This is the focus of an ongoing project, testing the hypothesis that an easy to assimilate carbon source added after exhaustion of the easily extractable material, can maintain the sulphide production.
- Full Text:
- Date Issued: 2005
International relations and change: a Kuhnian interpretation
- Authors: Schoeman, Jacobus
- Date: 2005
- Subjects: Kuhn, Thomas S Kuhn, Thomas S -- Criticism and interpretation International relations International relations -- Philosophy Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2830 , http://hdl.handle.net/10962/d1003040
- Description: Using notions of change developed by Thomas Kuhn, the thesis argues that the rise of globalisation and the end of the Cold War presented the Westphalian or state-centric paradigm of international relations with a Kuhnian paradigm “crisis”. As a result, both the theory and the practice of international relations are in the midst of (what Kuhn calls) a “paradigm shift”. Emerging from this shift is (what is described in this work as) “Access World” and “Denial World” – a particular global configuration of the practice of international relations. Kuhn’s idea of “incommensurability” seems to typify the relationship between the two components of this bifurcated configuration of the international. Both intellectual risk-taking and political courage are required if the ontological struggle raging between “Access World” and “Denial World” is to be settled. This will pave the way for a new paradigm to emerge. Kuhn provides us with the insight that, to achieve this ontological breakthrough, a fundamental change in our vision of the discipline of International Relations, but also of the world of everyday international relations, is required. This entails recasting the study of International Relations as an emancipatory project and by recognising the centrality of human beings in the practice of international relations. Only if this is done, will we be able to arrive at a cosmopolitan political bargain that is appropriate for the 21st century.
- Full Text:
- Date Issued: 2005
- Authors: Schoeman, Jacobus
- Date: 2005
- Subjects: Kuhn, Thomas S Kuhn, Thomas S -- Criticism and interpretation International relations International relations -- Philosophy Knowledge, Theory of
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2830 , http://hdl.handle.net/10962/d1003040
- Description: Using notions of change developed by Thomas Kuhn, the thesis argues that the rise of globalisation and the end of the Cold War presented the Westphalian or state-centric paradigm of international relations with a Kuhnian paradigm “crisis”. As a result, both the theory and the practice of international relations are in the midst of (what Kuhn calls) a “paradigm shift”. Emerging from this shift is (what is described in this work as) “Access World” and “Denial World” – a particular global configuration of the practice of international relations. Kuhn’s idea of “incommensurability” seems to typify the relationship between the two components of this bifurcated configuration of the international. Both intellectual risk-taking and political courage are required if the ontological struggle raging between “Access World” and “Denial World” is to be settled. This will pave the way for a new paradigm to emerge. Kuhn provides us with the insight that, to achieve this ontological breakthrough, a fundamental change in our vision of the discipline of International Relations, but also of the world of everyday international relations, is required. This entails recasting the study of International Relations as an emancipatory project and by recognising the centrality of human beings in the practice of international relations. Only if this is done, will we be able to arrive at a cosmopolitan political bargain that is appropriate for the 21st century.
- Full Text:
- Date Issued: 2005
The life history patterns of the polychaete, Terebrasabella heterouncinata, a pest of cultured abalone
- Authors: Simon, Carol Anne
- Date: 2005
- Subjects: Polychaeta -- Physiology Sabellidae -- Physiology Abalones -- Diseases Polychaeta -- Reproduction Sabellidae -- Reproduction Abalone culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5336 , http://hdl.handle.net/10962/d1005632
- Description: Terebrasabella heterouncinata is a small K-selected sabellid polychaete. It is a simultaneous hermaphrodite with a semi-continuous mode of reproduction, producing relatively few large eggs that are brooded within the parental burrow until the larvae emerge, to settle on the growing edge of the abalone shell. Despite its low fecundity, this worm has become problematic on abalone farms in South Africa. The present study was conducted to gain an understanding of the life history patterns of T. helerouncinata to determine how they contributed to the success of these worms under altered conditions. This study demonstrated that conditions prevalent on abalone farms were conducive to enhancing the reproductive success of this worm, and suggests that larger, more fecund worms may have been selected for in the decade that these worms have been present on the farms. Increased nutrient availability, and possibly the increased stability of the farm environment relative to its natural environment, has led to a 1.5-fold increase in the average size of the worms. Body size was found to be positively correlated with brood size, and this resulted in worms on farms brooding 3 to 4.5 times more offspring at a time than worms from wild abalone. The ability to increase the number of eggs produced at a time may have been limited by the fact that these worms have only two ovaries. Thus, the increase in fecundity may have been related primarily to the increase in the rate at which the eggs were laid by the worms on the farms, and the increase in the coelomic space available for the storage of these rapidly developing eggs. The ability to increase the rate at which oocytes develop may be related to the vitellogenic mechanisms employed by these worms. Vitellogenic oocytes are able to incorporate high molecular weight yolk precursors from the surrounding coelomic fluid through endocytotic activity. This may allow the oocytes to increase the rate at which they incorporate yolk material under conditions of nutrient enrichment. The increase in fecundity did not occur at the expense of offspring size and, presumably, quality. The increased reproductive output on the farms was compounded by a proportionate increase in the number of reproducing worms within the population. In addition, these worms are long-lived (worms from farmed abalone reached a maximum age of approximately 40 months) and exhibit negligible senescence. Thus, their reproductive output did not change significantly with an increase in age. Furthermore, the proportion of the reproductive worms did not decrease with an increase in age. Thus, within the age range tested, worms of all ages have the potential to make equal contributions to population growth. While diet and abalone stocking density could not be identified as having a significant effect on reproductive output and infestation rate under intensive culture conditions, it was demonstrated that in a naïve abalone population, the total intensity of infestation increased exponentially with time. This increase may be a consequence of an increase in fertilisation success. These worms continuously produce entaquasperm that are released into the water column. The sperm are collected by other individuals that then store the sperm in a single spermatheca. The ability to store sperm relieves individuals of a dependence on the synchronisation of spawning of eggs and sperm. As the population size and density increases, there could be more individuals releasing sperm into the water column, resulting in a continuous supply of sperm. The increased production of eggs would therefore not be constrained by a lack of sperm. The stored sperm are released into the brood chamber to fertilise eggs as they are laid, and this would probably increase the fertilisation success in the species. This study also provides evidence to suggest that reproduction in this worm has a seasonal component. Future studies should concentrate on measuring fertilisation success in greater detail, measuring the effect of season on reproduction, determining whether there are genetic differences between worms on farmed and wild abalone and determining whether wild worms have similar life-spans and age-related fecundity as worms on farms.
- Full Text:
- Date Issued: 2005
- Authors: Simon, Carol Anne
- Date: 2005
- Subjects: Polychaeta -- Physiology Sabellidae -- Physiology Abalones -- Diseases Polychaeta -- Reproduction Sabellidae -- Reproduction Abalone culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5336 , http://hdl.handle.net/10962/d1005632
- Description: Terebrasabella heterouncinata is a small K-selected sabellid polychaete. It is a simultaneous hermaphrodite with a semi-continuous mode of reproduction, producing relatively few large eggs that are brooded within the parental burrow until the larvae emerge, to settle on the growing edge of the abalone shell. Despite its low fecundity, this worm has become problematic on abalone farms in South Africa. The present study was conducted to gain an understanding of the life history patterns of T. helerouncinata to determine how they contributed to the success of these worms under altered conditions. This study demonstrated that conditions prevalent on abalone farms were conducive to enhancing the reproductive success of this worm, and suggests that larger, more fecund worms may have been selected for in the decade that these worms have been present on the farms. Increased nutrient availability, and possibly the increased stability of the farm environment relative to its natural environment, has led to a 1.5-fold increase in the average size of the worms. Body size was found to be positively correlated with brood size, and this resulted in worms on farms brooding 3 to 4.5 times more offspring at a time than worms from wild abalone. The ability to increase the number of eggs produced at a time may have been limited by the fact that these worms have only two ovaries. Thus, the increase in fecundity may have been related primarily to the increase in the rate at which the eggs were laid by the worms on the farms, and the increase in the coelomic space available for the storage of these rapidly developing eggs. The ability to increase the rate at which oocytes develop may be related to the vitellogenic mechanisms employed by these worms. Vitellogenic oocytes are able to incorporate high molecular weight yolk precursors from the surrounding coelomic fluid through endocytotic activity. This may allow the oocytes to increase the rate at which they incorporate yolk material under conditions of nutrient enrichment. The increase in fecundity did not occur at the expense of offspring size and, presumably, quality. The increased reproductive output on the farms was compounded by a proportionate increase in the number of reproducing worms within the population. In addition, these worms are long-lived (worms from farmed abalone reached a maximum age of approximately 40 months) and exhibit negligible senescence. Thus, their reproductive output did not change significantly with an increase in age. Furthermore, the proportion of the reproductive worms did not decrease with an increase in age. Thus, within the age range tested, worms of all ages have the potential to make equal contributions to population growth. While diet and abalone stocking density could not be identified as having a significant effect on reproductive output and infestation rate under intensive culture conditions, it was demonstrated that in a naïve abalone population, the total intensity of infestation increased exponentially with time. This increase may be a consequence of an increase in fertilisation success. These worms continuously produce entaquasperm that are released into the water column. The sperm are collected by other individuals that then store the sperm in a single spermatheca. The ability to store sperm relieves individuals of a dependence on the synchronisation of spawning of eggs and sperm. As the population size and density increases, there could be more individuals releasing sperm into the water column, resulting in a continuous supply of sperm. The increased production of eggs would therefore not be constrained by a lack of sperm. The stored sperm are released into the brood chamber to fertilise eggs as they are laid, and this would probably increase the fertilisation success in the species. This study also provides evidence to suggest that reproduction in this worm has a seasonal component. Future studies should concentrate on measuring fertilisation success in greater detail, measuring the effect of season on reproduction, determining whether there are genetic differences between worms on farmed and wild abalone and determining whether wild worms have similar life-spans and age-related fecundity as worms on farms.
- Full Text:
- Date Issued: 2005
The anatomy and distribution of the cyperaceae in the Eastern Cape region of South Africa
- Authors: Sonnenberg, Bernd Jürgen
- Date: 2005
- Subjects: Cyperaceae Cyperaceae -- Anatomy Cyperaceae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4228 , http://hdl.handle.net/10962/d1003797
- Description: The principal objective of this investigation, was to collect the family Cyperaceae and to study their leaf, bract and culm anatomy. The second was to examine the collection for unique structures or forms, whilst a third was to classify the Cyperaceae according to their photosynthetic structures and types. Distribution of the Cyperaceae within the broad region defined as the Eastern Cape would be influenced by rainfall pattern. It was expected that C₃ species would predominate in more mesic environments and habitats, whilst the C₄ species would be found in drier less favourable habitats. Collection within the region (November 1993 to late January 1997), yielded 106 species, totalling some 600 specimens. Both sub-families of the Cyperaceae (Caricoideae and Cyperoideae), eight tribes (Abildgaardieae, Cariceae, Cypereae, Hypotvtreae, Rhynchosporeae, Shoeneae, Sirpeae and Slerieae) and twenty five genera were found to be present. Sixty percent of the species were C₃ and forty percent were C₄. Sixteen new species, which had not been collected within the boundaries of the region previously were also found. Over 43 percent of the species collected had unique anatomical characteristics that appeared to be influenced by habitat and or climate influenced. These are the characters influenced by hydromorphic, mesomorphic and xeromorphic environments. These anatomical characters: Thickness of leaves and bracts; thickness of the adaxial and abaxial epidermis of the leaves and bracts; flush, sunken and raised stomata; presence or absence of bulliform cells; presence and distribution of sclerenchymatous structures; presence or absence of a hypodermis; presence or absence of cavities in the leaves, bracts and culms; mesophyll or ground tissue structure, and the presence or absence of secretary structures. A few noteworthy anatomical characters that are influenced by climate are present in Cladium mariscus subsp. jamaicense (Schoeneae), the Cariceae, the Cypereae and the Sclerieae. Within Cladium mariscus subsp. jamaicense the pseudo-dorsiventral leaves and bracts, as well as the large lamina cavities, containing trans-lamina girders are unique. Papillate epidermal cells are limited to the tribe Cariceae. In the Cypereae many of the species lack bulliform cells and hypodermal layers. In Pycreus cooperi (Cypereae) the vascular bundles of the leaves and bracts, appear to be stacked in rows, that are inter-spaced with lamina cavities. In the Sclerieae the mesophyll structure is specific to the species level. Unique anatomical characteristics were also present in the leaves, bracts and culms of the genus Carpha. In this genus distinctive lateral vascular bundles were present abutting the large bundles and/or midrib bundle. The most distinctive anatomical characteristics that could be used to separate the members of the Cyperaceae were the structures and associated structures related to the photosynthetic pathway. The Eastern Cape Cyperaceae could be divided into three distinct groups based on photosynthetic structure, namely one C₃, a C₄ and a potential C₃-C₄ intermediate group. The C₃ group was found to have non-radiate mesophyll and an outer parenchymatous sheath with small chloroplasts (Cariceae, Cyperaceae [in part], Hypolytreae (Chrysithrix capensis], Rhynchosporeae [R. brownii], Schoeneae, Scirpeae and Sclerieae). The C₄ group has radiate mesophyll and an inner parenchymatous sheath with enlarged chloroplasts (Kranz or PCR sheath). The C₄ species are present in tribes Abildgaardieae, Cypereae (in part) and Rhynchosporeae (R. barrosiana). In the Eastern Cape, a few species with C₃ anatomy have anatomical characteristics that are similar to the species with C₄ anatomy (Cyathocoma hexandra [bracts], Cyperus tennellus var. tennellus [leaves and bracts], Ficinia bulbosa [leaves], F. dura [leaves and bracts], F. lateralis coastal [leaves and bracts], F. oligantha [bracts], F. pingiour [bracts], F. stolonifera [leaves and bracts], F. tribracteata [leaves and bracts], F. zeyheri [leaves and bracts], Isolepis cernua [leaves and bracts], I. costata var. macra [bracts], Schoenus nigricans [leaves], Scirpus nodosus [bracts] and Tetraria cuspidata [leaves and bracts)). The vascular bundles within this intermediate group, fall within the Hattersleyand Watson (1975) minimal cell lateral count and maximal cell distal count criteria for C₄ grass species. However, no biochemical data exists to see whether they are C₃-C₄ intermediates or whether the Hattersley and Watson (1975) C₄ criteria for grasses applies to smaller, or scutiform Cyperaceae or not. Based on the results presented here, five distinct structural forms/types were found to be present in the C₃, C₄ and C₃-C₄ intermediate groups. The C₃ and the potential C₃-C₄ intermediate species may be divided into two types, based on the number of vascular sheaths present. In the first or A-type, vascular bundles are surrounded by two sheaths and in the more dominant B-type, by three. The A-type was found in the Cypereae (Cyperus denudatus and C. textilis) and most of the Scirpeae. B-type anatomy occurred in the Cariceae, Cypereae (c. difformis, C. pulcher, C. sphaerospermus, C. tennellus var. tennellus and P. mundii), Hypolytreae, Rhynchosporeae (R. brownii), Schoeneae, Scirpeae (Bolboschoenus maritimus, Ficinia cinnamomea, F. fascicularis, F. lateralis both, F. pingiour, the genus Fuirena, I. diabolica, I. fluitans, I. prolifera and Schoenoplectus paludicola) and Sclerieae tribes. Based on the vascular sheath structure, the C₄ species could be divided into three groups, namely bulbostyloid, chlorocyperoid and fimbristyloid, where the bulbostyloid structure occurred in Bulbostylis schoenoides. Cyperus (in part), Kyllinga, Mariscus and Pycreus (except P. mundii) had a chlorocyperoid structure. Genera with fimbristyloid structure were recorded in the genera Abildgaardia, Bulbostylis and Fimbristylis. The bulbostyloid type represents a potential a fifth C₄ anatomical type within the C₄ Cyperaceae. As a result of this observation, it is possible that the C₄ syndrome may have evolved five times in the Cyperaceae and not four as previously suggested by Bruhl and Perry (1995) and by Soros and Dengler (2001). The C₃ Cyperaceae species within the Eastern Cape are more dominant in higher elevation habitats the C₄ species, similar to the C₃ grasses. The only C₄ species that occur at high elevations are those with three sheaths. The C₃ and C₄ species within the region occur in similar low rainfall habitat ranges, where the C₄'s are more dominant in xeric habitats on drier soils than the C₃ species, similar to the grasses. Where more C₃ species occur in higher rainfall habitats than the C₄ species. With the exception of the Afromontane Bulbostylis schoenoides and R. barrosiana, the C₄ species similar to the grasses are dominant in high light and temperature habitats with low rainfall, unlike the C₄ Cyperaceae of Japan and America. Only five species occur in the desert like conditions of the Karoo-Namib biome (Cyperus laevigatus, C. rupestris var. rupestris, I. cernua, M. capensis and M. uitenhagensis), which have less than 250mm of rainfall per annum. Only three species are habitat-specific or may be endemic to a specific area within the Eastern Cape, namely A. capensis, Chrysithrix capensis and R. barrosiana. A. capensis in marshes on the Amatole mountains near Alice and Hogsback. C. capensis to the Tstsikamma mountains of the Wite Els Bosch forests. R. barrosiana to the marshlands of the Cape Morgan coastal Nature reserve at Kei Mouth. The anatomical types of the C₃ and more especially C₄ Cyperaceae are not specifically found in a particular rainfall regime or habitat type, which is contrary to the thesis hypothesis. However, the C₃ species are mostly correlated with hydrophytic to mesic habitats, with the exception of Ficinia and the two sheathed species. Ficinia is dominant in mesic grasslands and halophytic habitats. The two sheathed C₃ species are mostly present in halophytic habitats. The C₄ species are also more dominant in mesic to xerophytic grasslands, as expected in the hypothesis. Where only a few species occur in habitats correlated with increasing rainfall and temperature similar to the C₄ Cyperaceae of Japan and America. It may thus be that the development and evolution of the different C₄ anatomical forms (or phylogenetic forms) within the Cyperaceae may have enabled these species to establish themselves in habitats that were alien to their origins. It may be that the ability to regulate photoassimilate and water transport within the Cyperaceae enables their success in a dynamic and unpredictable climate, such as the Eastern Cape. Many of the anatomical characteristics reported in this thesis and its appendices are unique to the tribes, genera and/or species of the Eastern Cape Cyperaceae and thus may be valuable to future taxonomic classifications of the family. The research presented here should provide a good working platform for future, more detailed research on this often forgotten component of the vegetation.
- Full Text:
- Date Issued: 2005
- Authors: Sonnenberg, Bernd Jürgen
- Date: 2005
- Subjects: Cyperaceae Cyperaceae -- Anatomy Cyperaceae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4228 , http://hdl.handle.net/10962/d1003797
- Description: The principal objective of this investigation, was to collect the family Cyperaceae and to study their leaf, bract and culm anatomy. The second was to examine the collection for unique structures or forms, whilst a third was to classify the Cyperaceae according to their photosynthetic structures and types. Distribution of the Cyperaceae within the broad region defined as the Eastern Cape would be influenced by rainfall pattern. It was expected that C₃ species would predominate in more mesic environments and habitats, whilst the C₄ species would be found in drier less favourable habitats. Collection within the region (November 1993 to late January 1997), yielded 106 species, totalling some 600 specimens. Both sub-families of the Cyperaceae (Caricoideae and Cyperoideae), eight tribes (Abildgaardieae, Cariceae, Cypereae, Hypotvtreae, Rhynchosporeae, Shoeneae, Sirpeae and Slerieae) and twenty five genera were found to be present. Sixty percent of the species were C₃ and forty percent were C₄. Sixteen new species, which had not been collected within the boundaries of the region previously were also found. Over 43 percent of the species collected had unique anatomical characteristics that appeared to be influenced by habitat and or climate influenced. These are the characters influenced by hydromorphic, mesomorphic and xeromorphic environments. These anatomical characters: Thickness of leaves and bracts; thickness of the adaxial and abaxial epidermis of the leaves and bracts; flush, sunken and raised stomata; presence or absence of bulliform cells; presence and distribution of sclerenchymatous structures; presence or absence of a hypodermis; presence or absence of cavities in the leaves, bracts and culms; mesophyll or ground tissue structure, and the presence or absence of secretary structures. A few noteworthy anatomical characters that are influenced by climate are present in Cladium mariscus subsp. jamaicense (Schoeneae), the Cariceae, the Cypereae and the Sclerieae. Within Cladium mariscus subsp. jamaicense the pseudo-dorsiventral leaves and bracts, as well as the large lamina cavities, containing trans-lamina girders are unique. Papillate epidermal cells are limited to the tribe Cariceae. In the Cypereae many of the species lack bulliform cells and hypodermal layers. In Pycreus cooperi (Cypereae) the vascular bundles of the leaves and bracts, appear to be stacked in rows, that are inter-spaced with lamina cavities. In the Sclerieae the mesophyll structure is specific to the species level. Unique anatomical characteristics were also present in the leaves, bracts and culms of the genus Carpha. In this genus distinctive lateral vascular bundles were present abutting the large bundles and/or midrib bundle. The most distinctive anatomical characteristics that could be used to separate the members of the Cyperaceae were the structures and associated structures related to the photosynthetic pathway. The Eastern Cape Cyperaceae could be divided into three distinct groups based on photosynthetic structure, namely one C₃, a C₄ and a potential C₃-C₄ intermediate group. The C₃ group was found to have non-radiate mesophyll and an outer parenchymatous sheath with small chloroplasts (Cariceae, Cyperaceae [in part], Hypolytreae (Chrysithrix capensis], Rhynchosporeae [R. brownii], Schoeneae, Scirpeae and Sclerieae). The C₄ group has radiate mesophyll and an inner parenchymatous sheath with enlarged chloroplasts (Kranz or PCR sheath). The C₄ species are present in tribes Abildgaardieae, Cypereae (in part) and Rhynchosporeae (R. barrosiana). In the Eastern Cape, a few species with C₃ anatomy have anatomical characteristics that are similar to the species with C₄ anatomy (Cyathocoma hexandra [bracts], Cyperus tennellus var. tennellus [leaves and bracts], Ficinia bulbosa [leaves], F. dura [leaves and bracts], F. lateralis coastal [leaves and bracts], F. oligantha [bracts], F. pingiour [bracts], F. stolonifera [leaves and bracts], F. tribracteata [leaves and bracts], F. zeyheri [leaves and bracts], Isolepis cernua [leaves and bracts], I. costata var. macra [bracts], Schoenus nigricans [leaves], Scirpus nodosus [bracts] and Tetraria cuspidata [leaves and bracts)). The vascular bundles within this intermediate group, fall within the Hattersleyand Watson (1975) minimal cell lateral count and maximal cell distal count criteria for C₄ grass species. However, no biochemical data exists to see whether they are C₃-C₄ intermediates or whether the Hattersley and Watson (1975) C₄ criteria for grasses applies to smaller, or scutiform Cyperaceae or not. Based on the results presented here, five distinct structural forms/types were found to be present in the C₃, C₄ and C₃-C₄ intermediate groups. The C₃ and the potential C₃-C₄ intermediate species may be divided into two types, based on the number of vascular sheaths present. In the first or A-type, vascular bundles are surrounded by two sheaths and in the more dominant B-type, by three. The A-type was found in the Cypereae (Cyperus denudatus and C. textilis) and most of the Scirpeae. B-type anatomy occurred in the Cariceae, Cypereae (c. difformis, C. pulcher, C. sphaerospermus, C. tennellus var. tennellus and P. mundii), Hypolytreae, Rhynchosporeae (R. brownii), Schoeneae, Scirpeae (Bolboschoenus maritimus, Ficinia cinnamomea, F. fascicularis, F. lateralis both, F. pingiour, the genus Fuirena, I. diabolica, I. fluitans, I. prolifera and Schoenoplectus paludicola) and Sclerieae tribes. Based on the vascular sheath structure, the C₄ species could be divided into three groups, namely bulbostyloid, chlorocyperoid and fimbristyloid, where the bulbostyloid structure occurred in Bulbostylis schoenoides. Cyperus (in part), Kyllinga, Mariscus and Pycreus (except P. mundii) had a chlorocyperoid structure. Genera with fimbristyloid structure were recorded in the genera Abildgaardia, Bulbostylis and Fimbristylis. The bulbostyloid type represents a potential a fifth C₄ anatomical type within the C₄ Cyperaceae. As a result of this observation, it is possible that the C₄ syndrome may have evolved five times in the Cyperaceae and not four as previously suggested by Bruhl and Perry (1995) and by Soros and Dengler (2001). The C₃ Cyperaceae species within the Eastern Cape are more dominant in higher elevation habitats the C₄ species, similar to the C₃ grasses. The only C₄ species that occur at high elevations are those with three sheaths. The C₃ and C₄ species within the region occur in similar low rainfall habitat ranges, where the C₄'s are more dominant in xeric habitats on drier soils than the C₃ species, similar to the grasses. Where more C₃ species occur in higher rainfall habitats than the C₄ species. With the exception of the Afromontane Bulbostylis schoenoides and R. barrosiana, the C₄ species similar to the grasses are dominant in high light and temperature habitats with low rainfall, unlike the C₄ Cyperaceae of Japan and America. Only five species occur in the desert like conditions of the Karoo-Namib biome (Cyperus laevigatus, C. rupestris var. rupestris, I. cernua, M. capensis and M. uitenhagensis), which have less than 250mm of rainfall per annum. Only three species are habitat-specific or may be endemic to a specific area within the Eastern Cape, namely A. capensis, Chrysithrix capensis and R. barrosiana. A. capensis in marshes on the Amatole mountains near Alice and Hogsback. C. capensis to the Tstsikamma mountains of the Wite Els Bosch forests. R. barrosiana to the marshlands of the Cape Morgan coastal Nature reserve at Kei Mouth. The anatomical types of the C₃ and more especially C₄ Cyperaceae are not specifically found in a particular rainfall regime or habitat type, which is contrary to the thesis hypothesis. However, the C₃ species are mostly correlated with hydrophytic to mesic habitats, with the exception of Ficinia and the two sheathed species. Ficinia is dominant in mesic grasslands and halophytic habitats. The two sheathed C₃ species are mostly present in halophytic habitats. The C₄ species are also more dominant in mesic to xerophytic grasslands, as expected in the hypothesis. Where only a few species occur in habitats correlated with increasing rainfall and temperature similar to the C₄ Cyperaceae of Japan and America. It may thus be that the development and evolution of the different C₄ anatomical forms (or phylogenetic forms) within the Cyperaceae may have enabled these species to establish themselves in habitats that were alien to their origins. It may be that the ability to regulate photoassimilate and water transport within the Cyperaceae enables their success in a dynamic and unpredictable climate, such as the Eastern Cape. Many of the anatomical characteristics reported in this thesis and its appendices are unique to the tribes, genera and/or species of the Eastern Cape Cyperaceae and thus may be valuable to future taxonomic classifications of the family. The research presented here should provide a good working platform for future, more detailed research on this often forgotten component of the vegetation.
- Full Text:
- Date Issued: 2005
An investigation into the antidepressant activity of hypericum perforatum
- Authors: Stephens, Linda Lee
- Date: 2005
- Subjects: Hypericum perforatum -- Physiological effect Hypericum perforatum -- Therapeutic use Antidepressants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3793 , http://hdl.handle.net/10962/d1003271
- Description: Hypericum perforatum is a herbal medicine that has been used for centuries for the treatment of depression. Many studies have been conducted in the Northern hemisphere on the efficacy of the HP extracts produced there. These studies include clinical trials and pharmacological investigations using a standardised HP extract or a fraction of the HP extract containing certain compounds, such as hypericin, pseudohypericin, hyperforin and several of the flavonoids thought to be responsible for the antidepressant activity. The mechanism of action of HP and its constituents is still not completely clear and it is speculated that the antidepressant activity is the result of several of the compounds acting synergistically. HP is indigenous to and also cultivated in the Western Cape of South Africa. Extracts from these plants are sold in the local health shops and there are no previous studies evaluating the efficacy of these products. The aim of this thesis is to investigate the antidepressant activity of one of these products and two of its constituents, quercetin and caffeic acid, to gain further insight into their mode of antidepressant action and to compare these results with similar studies which used a standardised extract produced in the northern hemisphere. The first study investigated the effect of HP, quercetin and caffeic acid on pineal metabolism. Changes in the synthesis of melatonin produced by the pineal gland have been implicated in depression. The results showed an increase in the level of melatonin produced in the animals treated with quercetin, which suggests that this compound may mediate antidepressant activity through such a mechanism. There are no previous reports on the in vivo effects of HP or any of its constituents on pineal metabolism. The second study investigated the effect of HP, quercetin and caffeic acid on the activity of the liver enzyme, tryptophan-2,3-dioxygenase (TDO). Inhibition of this enzyme has been shown to increase plasma levels of tryptophan, a precursor of serotonin and thereby result in increased serotonin levels in the brain. Low levels of serotonin in the brain have been implicated in depression. This study revealed significant inhibition of TDO by caffeic acid and this suggests that this constituent of HP could be contributing to its antidepressant activity through such a mechanism. There are no previous reports investigating the in vivo effect of HP or any of its constituents on TDO activity. Modulation of the levels of indoleamines, serotonin (5-HT) and dopamine (DA) as well as the metabolites, 3,4 dihydroxyphenyl acetic acid (DOPAC), 5-hydroxyindole acetic acid (5-HIAA) and homovallinic acid (HVA) in the brain have been implicated in the neuropharmacology of depression. Different studies using enzyme-linked immunosorbant assay (ELISA), high performance liquid chromatography with electrochemical detection (HPLC-ECD) and liquid chromatography-mass spectrometry (LC-MS) were used to determine changes in the levels of these indoleamines brought about after treatment with HP caffeic acid and quercetin. The results of the ELISA study showed significant increases in 5-HT levels in the brains of the animals treated with caffeic acid and quercetin. The results of the HPLC-ECD studies also revealed significant increases in 5-HT levels and a decrease in the turnover of 5-HT in the animals treated with quercetin. A significant increase in DA levels in the animals treated with quercetin was shown in both the HPLC-ECD and LC-MS studies. There was also an increase in DA turnover in the animals treated with HP shown in the HPLC-ECD and LC-MS studies. These results suggest that HP and its constituents, quercetin and caffeic acid mediate their antidepressant effects through serotonergic and dopaminergic neurotransmission. Adaptive changes in the density of b-adrenergic (b-AR), 5-HT2 and N-methyl-D-aspartate (NMDA) receptors have been implicated in depression. Several studies, investigating the effect of treatment with HP and quercetin on these different receptor densities, were undertaken using radioactive binding assays. Treatment with HP resulted in significant down regulation of b-AR and NMDA receptor densities and up-regulation of 5HT2 receptors. The effects on the b-AR and 5-HT2 receptors are similar to the results reported using HP in the Northern hemisphere, but the effect on the NMDA receptors is novel providing insight into the mode of action of HP. Apoptosis of neuronal cells has been implicated in neuro-degenerative and depressive disorders. Detection of apoptosis, using fluorescent microscopy observed through the labelling of DNA strand breaks, showed a decrease in the amount of apoptosis in the animals treated with HP and quercetin. This adds further support for the use of HP as an antidepressant and these results are similar to results reported from the Northern hemisphere. The results of all these studies suggest that the quality of the locally produced tincture is similar in efficacy to that of the standardised product of the Northern hemisphere.
- Full Text:
- Date Issued: 2005
- Authors: Stephens, Linda Lee
- Date: 2005
- Subjects: Hypericum perforatum -- Physiological effect Hypericum perforatum -- Therapeutic use Antidepressants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3793 , http://hdl.handle.net/10962/d1003271
- Description: Hypericum perforatum is a herbal medicine that has been used for centuries for the treatment of depression. Many studies have been conducted in the Northern hemisphere on the efficacy of the HP extracts produced there. These studies include clinical trials and pharmacological investigations using a standardised HP extract or a fraction of the HP extract containing certain compounds, such as hypericin, pseudohypericin, hyperforin and several of the flavonoids thought to be responsible for the antidepressant activity. The mechanism of action of HP and its constituents is still not completely clear and it is speculated that the antidepressant activity is the result of several of the compounds acting synergistically. HP is indigenous to and also cultivated in the Western Cape of South Africa. Extracts from these plants are sold in the local health shops and there are no previous studies evaluating the efficacy of these products. The aim of this thesis is to investigate the antidepressant activity of one of these products and two of its constituents, quercetin and caffeic acid, to gain further insight into their mode of antidepressant action and to compare these results with similar studies which used a standardised extract produced in the northern hemisphere. The first study investigated the effect of HP, quercetin and caffeic acid on pineal metabolism. Changes in the synthesis of melatonin produced by the pineal gland have been implicated in depression. The results showed an increase in the level of melatonin produced in the animals treated with quercetin, which suggests that this compound may mediate antidepressant activity through such a mechanism. There are no previous reports on the in vivo effects of HP or any of its constituents on pineal metabolism. The second study investigated the effect of HP, quercetin and caffeic acid on the activity of the liver enzyme, tryptophan-2,3-dioxygenase (TDO). Inhibition of this enzyme has been shown to increase plasma levels of tryptophan, a precursor of serotonin and thereby result in increased serotonin levels in the brain. Low levels of serotonin in the brain have been implicated in depression. This study revealed significant inhibition of TDO by caffeic acid and this suggests that this constituent of HP could be contributing to its antidepressant activity through such a mechanism. There are no previous reports investigating the in vivo effect of HP or any of its constituents on TDO activity. Modulation of the levels of indoleamines, serotonin (5-HT) and dopamine (DA) as well as the metabolites, 3,4 dihydroxyphenyl acetic acid (DOPAC), 5-hydroxyindole acetic acid (5-HIAA) and homovallinic acid (HVA) in the brain have been implicated in the neuropharmacology of depression. Different studies using enzyme-linked immunosorbant assay (ELISA), high performance liquid chromatography with electrochemical detection (HPLC-ECD) and liquid chromatography-mass spectrometry (LC-MS) were used to determine changes in the levels of these indoleamines brought about after treatment with HP caffeic acid and quercetin. The results of the ELISA study showed significant increases in 5-HT levels in the brains of the animals treated with caffeic acid and quercetin. The results of the HPLC-ECD studies also revealed significant increases in 5-HT levels and a decrease in the turnover of 5-HT in the animals treated with quercetin. A significant increase in DA levels in the animals treated with quercetin was shown in both the HPLC-ECD and LC-MS studies. There was also an increase in DA turnover in the animals treated with HP shown in the HPLC-ECD and LC-MS studies. These results suggest that HP and its constituents, quercetin and caffeic acid mediate their antidepressant effects through serotonergic and dopaminergic neurotransmission. Adaptive changes in the density of b-adrenergic (b-AR), 5-HT2 and N-methyl-D-aspartate (NMDA) receptors have been implicated in depression. Several studies, investigating the effect of treatment with HP and quercetin on these different receptor densities, were undertaken using radioactive binding assays. Treatment with HP resulted in significant down regulation of b-AR and NMDA receptor densities and up-regulation of 5HT2 receptors. The effects on the b-AR and 5-HT2 receptors are similar to the results reported using HP in the Northern hemisphere, but the effect on the NMDA receptors is novel providing insight into the mode of action of HP. Apoptosis of neuronal cells has been implicated in neuro-degenerative and depressive disorders. Detection of apoptosis, using fluorescent microscopy observed through the labelling of DNA strand breaks, showed a decrease in the amount of apoptosis in the animals treated with HP and quercetin. This adds further support for the use of HP as an antidepressant and these results are similar to results reported from the Northern hemisphere. The results of all these studies suggest that the quality of the locally produced tincture is similar in efficacy to that of the standardised product of the Northern hemisphere.
- Full Text:
- Date Issued: 2005
A history of the direct taxation of the African people of Kenya, 1895-1973
- Authors: Tarus, Isaac Kipsang
- Date: 2005
- Subjects: Mau Mau -- History Taxation -- Kenya Tax collection -- Kenya Fiscal policy -- Kenya Kenya -- Economic policy Kenya -- History -- 1895-1963
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2561 , http://hdl.handle.net/10962/d1002414
- Description: This study examines the origin, the manifestation and impact of the direct taxation of Africans in Kenya. While the state had several reasons for imposing taxation on Africans, the basic factor weighed on the need for a definitive source of revenue. For most of the colonial period, this aggregated to about 37½ percent of the total revenues. The thesis shows how taxes were collected from Africans, how this led to participation in the cash economy and how they continually resisted and evaded such taxation. Tax collection was synonymous with colonialism and this was manifested through the central role of chiefs, who used taxes and force to coerce Africans into migrant wage labour. Through taxation policies, legislation and African resourcefulness, migrant wage labour served the needs of a colonial capitalist settler economy. In this way, the colonial state revealed its capacity for dominance, power and exploitation. Evidence has been adduced to show that African taxation was an important factor in Kenya’s administrative, political and economic development. The policy of African taxation, land loss and poor working conditions are remembered as having interfered with African mechanisms for accumulating wealth. One of the main objections of the payment of taxes was the manner of its collection. Those unable to pay were imprisoned or detained while many took to instant flight at the sight of the tax collector. The thesis shows that in spite of all these harsh tax collection methods, peasants remained largely resilient and industrious. The Mau Mau movement was the culmination of various peasant grievances in which the colonial state used steep taxation as a counter-insurgency measure. Kenya’s independence in 1963, however, never altered the predatory nature of the state. Subtle, opportunistic and overt ways continued to be used to extract taxes from the peasants and the working class. It was not until 1973 that the much-hated colonial poll tax that had been renamed as graduated poll tax was abolished and replaced by indirect taxation. Finally, taxation like other colonial legacies has endured and has become one of the most important sources of revenue for the government to manage its fiscal policies.
- Full Text:
- Date Issued: 2005
- Authors: Tarus, Isaac Kipsang
- Date: 2005
- Subjects: Mau Mau -- History Taxation -- Kenya Tax collection -- Kenya Fiscal policy -- Kenya Kenya -- Economic policy Kenya -- History -- 1895-1963
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2561 , http://hdl.handle.net/10962/d1002414
- Description: This study examines the origin, the manifestation and impact of the direct taxation of Africans in Kenya. While the state had several reasons for imposing taxation on Africans, the basic factor weighed on the need for a definitive source of revenue. For most of the colonial period, this aggregated to about 37½ percent of the total revenues. The thesis shows how taxes were collected from Africans, how this led to participation in the cash economy and how they continually resisted and evaded such taxation. Tax collection was synonymous with colonialism and this was manifested through the central role of chiefs, who used taxes and force to coerce Africans into migrant wage labour. Through taxation policies, legislation and African resourcefulness, migrant wage labour served the needs of a colonial capitalist settler economy. In this way, the colonial state revealed its capacity for dominance, power and exploitation. Evidence has been adduced to show that African taxation was an important factor in Kenya’s administrative, political and economic development. The policy of African taxation, land loss and poor working conditions are remembered as having interfered with African mechanisms for accumulating wealth. One of the main objections of the payment of taxes was the manner of its collection. Those unable to pay were imprisoned or detained while many took to instant flight at the sight of the tax collector. The thesis shows that in spite of all these harsh tax collection methods, peasants remained largely resilient and industrious. The Mau Mau movement was the culmination of various peasant grievances in which the colonial state used steep taxation as a counter-insurgency measure. Kenya’s independence in 1963, however, never altered the predatory nature of the state. Subtle, opportunistic and overt ways continued to be used to extract taxes from the peasants and the working class. It was not until 1973 that the much-hated colonial poll tax that had been renamed as graduated poll tax was abolished and replaced by indirect taxation. Finally, taxation like other colonial legacies has endured and has become one of the most important sources of revenue for the government to manage its fiscal policies.
- Full Text:
- Date Issued: 2005
Modeling and measurement of torqued procession in radio pulsars
- Authors: Tiplady, Adrian John
- Date: 2005
- Subjects: Pulsars , Radio telescopes , Radio astronomy , Precession , Hartebeeshoek Radio Astronomy Observatory (HartRAO)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5475 , http://hdl.handle.net/10962/d1005260
- Description: The long term isolated pulsar monitoring program, which commenced in 1984 using the 26 m radio telescope at the Hartebeeshoek Radio Astronomy Observatory (HartRAO), has produced high resolution timing residual data over long timespans. This has enabled the analysis of observed spin down behaviour for 27 braking pulsars, most of which have dataspans longer than 14 years. The phenomenology of observed timing residuals of certain pulsars can be explained by pseudo periodic effects such as precession. Analytic and numerical models are developed to study the kinematic and dynamic behaviour of isolated but torqued precessing pulsars. The predicted timing residual behaviour of the models is characterised, and confronted with timing data from selected pulsars. Cyclic variations in the observed timing residuals of PSR B1642-03, PSR B1323-58 and PSR B1557-50 are fitted with a torqued precession model. The phenomenology of the observed timing behaviour of these pulsars can be explained by the precession models, but precise model fitting was not possible. This is not surprising given that the complexity of the pulsar systems is not completely described by the model. The extension of the pulsar monitoring program at HartRAO is used as motivation for the design and development of a new low cost, multi-purpose digital pulsar receiver. The instrument is implemented using a hybrid filterbank architecture, consisting of an analogue frontend and digital backend, to perform incoherent dedispersion. The design of a polyphase filtering system, which will consolidate multiple processing units into a single filtering solution, is discussed for future implementation.
- Full Text:
- Date Issued: 2005
- Authors: Tiplady, Adrian John
- Date: 2005
- Subjects: Pulsars , Radio telescopes , Radio astronomy , Precession , Hartebeeshoek Radio Astronomy Observatory (HartRAO)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5475 , http://hdl.handle.net/10962/d1005260
- Description: The long term isolated pulsar monitoring program, which commenced in 1984 using the 26 m radio telescope at the Hartebeeshoek Radio Astronomy Observatory (HartRAO), has produced high resolution timing residual data over long timespans. This has enabled the analysis of observed spin down behaviour for 27 braking pulsars, most of which have dataspans longer than 14 years. The phenomenology of observed timing residuals of certain pulsars can be explained by pseudo periodic effects such as precession. Analytic and numerical models are developed to study the kinematic and dynamic behaviour of isolated but torqued precessing pulsars. The predicted timing residual behaviour of the models is characterised, and confronted with timing data from selected pulsars. Cyclic variations in the observed timing residuals of PSR B1642-03, PSR B1323-58 and PSR B1557-50 are fitted with a torqued precession model. The phenomenology of the observed timing behaviour of these pulsars can be explained by the precession models, but precise model fitting was not possible. This is not surprising given that the complexity of the pulsar systems is not completely described by the model. The extension of the pulsar monitoring program at HartRAO is used as motivation for the design and development of a new low cost, multi-purpose digital pulsar receiver. The instrument is implemented using a hybrid filterbank architecture, consisting of an analogue frontend and digital backend, to perform incoherent dedispersion. The design of a polyphase filtering system, which will consolidate multiple processing units into a single filtering solution, is discussed for future implementation.
- Full Text:
- Date Issued: 2005