Synthesis of novel inhibitors of 1-Deoxy-D-xylulose-5-phosphate reductoisomerase as potential anti-malarial lead compounds
- Authors: Mutorwa, Marius Kudumo
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Malaria -- Chemotherapy Drug development Lead compounds Phosphonates Phosphonic acids Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4372 , http://hdl.handle.net/10962/d1005037
- Description: This research has focused on the development of novel substrate mimics as potential DXR inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate-independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate (DOXP) into 2C-methyl-D-erithrytol 4-phosphate (MEP) and has been validated as an attractive target for the development of novel anti-malarial chemotherapeutic agents. Reaction of various amines with specially prepared 4-phosphonated crotonic acid in the presence of the peptide coupling reagent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), has afforded a series of amido-phosphonate esters in moderate to good yields (48% - 73%) which, using a RuCl₃/CeCl₃/NaIO₄ catalyst system, have been dihydroxylated to furnish the dihydroxy-amido phosphonate ester pro-drugs; subsequent hydrolysis under microwave irradiation has afforded the corresponding phosphonic acids. A second series of potential inhibitors viz., 3-substituted aniline-derived phosphonate esters, their corresponding phosphonic acids and mono-sodium salts, have also been successfully synthesised. In these compounds, the essential functional groups are separated by one, two, three or four methylene groups, Deprotonation of the 3-substituted aniline substrates, followed by reaction with the appropriate ω-chloroalkanoyl chloride produced the ω-chloroamide intermediates, which were subjected to the Michaelis-Arbuzov reaction to afford the diethyl phosphonate esters in moderate to good yields (48% - 74%). Microwave-assisted TMSBrmediated cleavage of the phosphonate esters furnished the phosphonic acids, neutralisation of which afforded the mono-sodium salts. Furan-derived phosphate esters and phosphonic acids have been prepared as conformationally-restricted DOXP analogues. Functionalization at C-5 of the trityl-protected furan was achieved using the Vilsmeier-Haack formylation and Friedel-Crafts acylation reactions and, following de-tritylation, phosphorylation and oximation, using hydroxylamine hydrochloride, the novel oxime derivatives have been isolated as a third series of potential DXR inhibitors in very good yields (87% - 96%). Finally, in order to exploit an additional binding pocket in the PƒDXR active site, a series of N-benzylated phosphoramidic derivatives were obtained in seven steps from the starting material, diethyl phosphoramidate. The known inhibitors, fosmidomycin and its acetyl derivative FR900098, were also successfully synthesised as standards for STD-NMR binding and inhibition assays. In all, over 200 compounds (136 novel) have been prepared and appropriately characterised using 1-and 2-D NMR and IR spectroscopic analysis and, where necessary, HRMS or combustion analysis. Saturation Transfer Difference (STD) protein-NMR experiments, undertaken using selected compounds, have revealed binding of most of the ligands examined to EcDXR. Computersimulated docking studies have also been used to explore the preferred ligand-binding conformations and interactions between the ligands and essential DXR active-site residues, while DXR-enzyme inhibition assays of selected synthesised ligands have revealed certain patterns of inhibitory activity.
- Full Text:
- Date Issued: 2011
- Authors: Mutorwa, Marius Kudumo
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Malaria -- Chemotherapy Drug development Lead compounds Phosphonates Phosphonic acids Ligands
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4372 , http://hdl.handle.net/10962/d1005037
- Description: This research has focused on the development of novel substrate mimics as potential DXR inhibitors of 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR), an essential enzyme in the mevalonate-independent pathway for the biosynthesis of isoprenoids in Plasmodium falciparum. DXR mediates the isomerisation and reduction of 1-deoxy-D-xylulose-5-phosphate (DOXP) into 2C-methyl-D-erithrytol 4-phosphate (MEP) and has been validated as an attractive target for the development of novel anti-malarial chemotherapeutic agents. Reaction of various amines with specially prepared 4-phosphonated crotonic acid in the presence of the peptide coupling reagent, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC), has afforded a series of amido-phosphonate esters in moderate to good yields (48% - 73%) which, using a RuCl₃/CeCl₃/NaIO₄ catalyst system, have been dihydroxylated to furnish the dihydroxy-amido phosphonate ester pro-drugs; subsequent hydrolysis under microwave irradiation has afforded the corresponding phosphonic acids. A second series of potential inhibitors viz., 3-substituted aniline-derived phosphonate esters, their corresponding phosphonic acids and mono-sodium salts, have also been successfully synthesised. In these compounds, the essential functional groups are separated by one, two, three or four methylene groups, Deprotonation of the 3-substituted aniline substrates, followed by reaction with the appropriate ω-chloroalkanoyl chloride produced the ω-chloroamide intermediates, which were subjected to the Michaelis-Arbuzov reaction to afford the diethyl phosphonate esters in moderate to good yields (48% - 74%). Microwave-assisted TMSBrmediated cleavage of the phosphonate esters furnished the phosphonic acids, neutralisation of which afforded the mono-sodium salts. Furan-derived phosphate esters and phosphonic acids have been prepared as conformationally-restricted DOXP analogues. Functionalization at C-5 of the trityl-protected furan was achieved using the Vilsmeier-Haack formylation and Friedel-Crafts acylation reactions and, following de-tritylation, phosphorylation and oximation, using hydroxylamine hydrochloride, the novel oxime derivatives have been isolated as a third series of potential DXR inhibitors in very good yields (87% - 96%). Finally, in order to exploit an additional binding pocket in the PƒDXR active site, a series of N-benzylated phosphoramidic derivatives were obtained in seven steps from the starting material, diethyl phosphoramidate. The known inhibitors, fosmidomycin and its acetyl derivative FR900098, were also successfully synthesised as standards for STD-NMR binding and inhibition assays. In all, over 200 compounds (136 novel) have been prepared and appropriately characterised using 1-and 2-D NMR and IR spectroscopic analysis and, where necessary, HRMS or combustion analysis. Saturation Transfer Difference (STD) protein-NMR experiments, undertaken using selected compounds, have revealed binding of most of the ligands examined to EcDXR. Computersimulated docking studies have also been used to explore the preferred ligand-binding conformations and interactions between the ligands and essential DXR active-site residues, while DXR-enzyme inhibition assays of selected synthesised ligands have revealed certain patterns of inhibitory activity.
- Full Text:
- Date Issued: 2011
Performance improvement in South African construction
- Authors: Emuze, Fidelis Abumere
- Date: 2011
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9678 , http://hdl.handle.net/10948/1642 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Description: In general, dreams are conceived, ideas are conceptualised, and initiatives are embarked upon in order to alter the state of realities. Dreams change realities; when mechanisms are put in place to realise them, dreams succeed. However, anecdotal evidence as well as empirical findings has continued to reiterate the difficulties associated with realising dreams related to construction projects. Extending the „dream‟ analogy to the South African construction industry context therefore paints an uninspiring picture. Dreams associated with construction do not have a 100% chance of becoming realities as evident in reported poor project performance in the industry. Shattered dreams in the form of poor performing projects, poorly implemented construction processes, or worst, projects delivered at the expense of unexpected cost to the client as a direct result of poor H&S or time overruns, negate the intent of dreams. This thesis is primarily concerned with project performance related bottlenecks in South African construction. After an extensive review of related literature that entails the analysis of publications related to non-value adding activities (NVAAs), supply chain management (SCM), and system dynamics (SD) in the construction project management realm, an exhaustive mixed-mode quantitative survey was conducted among key participants in the South African infrastructure sector. Public sector clients, consulting engineers and contractors that were involved in civil engineering projects were surveyed repeatedly with approximately five survey instruments at convenient intervals. Results arising from the study, inter-alia, indicate that: an appreciable amount of NVAAs occur in South African construction; these NVAAs become further compounded when propagated into other value adding activities (VAAs) in the construction process; the identified NVAAs equally perpetrate the menace associated with poor performance to the detriment of the achievement of cost, H&S, quality, and time project targets, and the root cause of these NVAAs that often contribute to poor performance is not far from the much reported „shortage of skills‟ in South Africa. Notable contributions to the body of knowledge include SD models are extendable regardless of the source of their empirical data as evident in the qualitative models proposed in this study; within the SD domain, it is advisable to consider the „competence‟ of individuals assigned to tasks especially in a developing country as this study revealed that human resources issues predominate among the sources of NVAAs that eventuate in a range of poor project performance; the NVAAs that occur, and their causes on projects are perceived to be due to lapses and / or inadequacies that involved the entire construction supply chain; there is no single construction process / task that is immune from being affected by NVAAs; and within the South African, and by implication construction context generally iii in developing countries, the adequacy of required knowledge among project stakeholders is the most crucial determinant of project performance. As opposed to what is obtainable in developed countries, the construction industry in developing countries, particularly in South Africa, should take advantage of knowledge management (KM) techniques such as brainstorming, communities of practices, and face-to-face interactions. These techniques can be driven through appropriate mentorship programmes, industry focused built environment education, and other human resources driven avenues that do not necessarily require substantial investment in technologies, so that to a large extent organisations in the industry can prioritise KM, and thereafter, continually engage in it for future performance improvement. Using inferential statistical methods for hypotheses testing, and SD concepts for creating qualitative models led to a range of recommendations which, inter-alia, propose that halting the tide of NVAAs and poor performance requires the management of both tacit and explicit knowledge gained in construction; and most importantly, it requires the assurance that „competence‟ is the overriding criteria for selecting project partners, and also, for assigning either design or construction related activities to responsible parties involved in project realisation in South Africa. In effect, in order to engender a culture of continuous improvement in South African construction, other considerations should be subservient to „competence‟ in the construction supply chain. Competence must be located among everyone involved in project realisation, that is, enhancing the competence of all involved in project realisation is as good as ensuring performance improvement, which in turn, equates to the acceleration of project delivery in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Emuze, Fidelis Abumere
- Date: 2011
- Subjects: Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9678 , http://hdl.handle.net/10948/1642 , Construction industry -- South Africa -- Management , Project management -- South Africa , Construction projects -- Management , Business logistics -- South Africa -- Management
- Description: In general, dreams are conceived, ideas are conceptualised, and initiatives are embarked upon in order to alter the state of realities. Dreams change realities; when mechanisms are put in place to realise them, dreams succeed. However, anecdotal evidence as well as empirical findings has continued to reiterate the difficulties associated with realising dreams related to construction projects. Extending the „dream‟ analogy to the South African construction industry context therefore paints an uninspiring picture. Dreams associated with construction do not have a 100% chance of becoming realities as evident in reported poor project performance in the industry. Shattered dreams in the form of poor performing projects, poorly implemented construction processes, or worst, projects delivered at the expense of unexpected cost to the client as a direct result of poor H&S or time overruns, negate the intent of dreams. This thesis is primarily concerned with project performance related bottlenecks in South African construction. After an extensive review of related literature that entails the analysis of publications related to non-value adding activities (NVAAs), supply chain management (SCM), and system dynamics (SD) in the construction project management realm, an exhaustive mixed-mode quantitative survey was conducted among key participants in the South African infrastructure sector. Public sector clients, consulting engineers and contractors that were involved in civil engineering projects were surveyed repeatedly with approximately five survey instruments at convenient intervals. Results arising from the study, inter-alia, indicate that: an appreciable amount of NVAAs occur in South African construction; these NVAAs become further compounded when propagated into other value adding activities (VAAs) in the construction process; the identified NVAAs equally perpetrate the menace associated with poor performance to the detriment of the achievement of cost, H&S, quality, and time project targets, and the root cause of these NVAAs that often contribute to poor performance is not far from the much reported „shortage of skills‟ in South Africa. Notable contributions to the body of knowledge include SD models are extendable regardless of the source of their empirical data as evident in the qualitative models proposed in this study; within the SD domain, it is advisable to consider the „competence‟ of individuals assigned to tasks especially in a developing country as this study revealed that human resources issues predominate among the sources of NVAAs that eventuate in a range of poor project performance; the NVAAs that occur, and their causes on projects are perceived to be due to lapses and / or inadequacies that involved the entire construction supply chain; there is no single construction process / task that is immune from being affected by NVAAs; and within the South African, and by implication construction context generally iii in developing countries, the adequacy of required knowledge among project stakeholders is the most crucial determinant of project performance. As opposed to what is obtainable in developed countries, the construction industry in developing countries, particularly in South Africa, should take advantage of knowledge management (KM) techniques such as brainstorming, communities of practices, and face-to-face interactions. These techniques can be driven through appropriate mentorship programmes, industry focused built environment education, and other human resources driven avenues that do not necessarily require substantial investment in technologies, so that to a large extent organisations in the industry can prioritise KM, and thereafter, continually engage in it for future performance improvement. Using inferential statistical methods for hypotheses testing, and SD concepts for creating qualitative models led to a range of recommendations which, inter-alia, propose that halting the tide of NVAAs and poor performance requires the management of both tacit and explicit knowledge gained in construction; and most importantly, it requires the assurance that „competence‟ is the overriding criteria for selecting project partners, and also, for assigning either design or construction related activities to responsible parties involved in project realisation in South Africa. In effect, in order to engender a culture of continuous improvement in South African construction, other considerations should be subservient to „competence‟ in the construction supply chain. Competence must be located among everyone involved in project realisation, that is, enhancing the competence of all involved in project realisation is as good as ensuring performance improvement, which in turn, equates to the acceleration of project delivery in South Africa.
- Full Text:
- Date Issued: 2011
Fundamental investigations into the factors affecting the response of laccase-based electrochemical biosensors
- Authors: Fogel, Ronen
- Date: 2011
- Subjects: Laccase Phenols Biosensors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4073 , http://hdl.handle.net/10962/d1007166
- Description: Given their widespread effects and distribution in both natural and industrial environments, the monitoring of phenolic compounds is of considerable analytical interest. Electrochemical biosensor technologies, in particular those comprising laccase enzymes, afford many potential benefits to address this analytical need. However, several key factors affecting sensor response currently limit their applicability. This Thesis reports on the fabrication and optimisation of an electrochemical laccase-based biosensor towards the application of the monitoring of phenolic compounds. Selected factors considered to affect sensor response were investigated using the optimised biosensor. These included: electrochemical, biochemical and substrate-dependent factors, which were found to intersect in modulating biosensor response signals. Through the application of transducer-dependent and substrate-dependent parameters, the selective and simultaneous detection of a mixture of different phenolic analytes is successfully demonstrated. This Thesis also investigates the use of Quartz-Crystal Microbalance with Dissipation (QCM-D) technology, an analytical technique that measures physical parameters of thin-film structures, towards the successful monitoring of enzyme immobilisation strategies. These strategies are fundamental to the successful fabrication of biosensors, and the real-time monitoring of immobilised film formations is of considerable research interest. In the studies reported on in this Thesis, QCM-D technology was demonstrated to be an effective complementary technology in the prediction of film immobilisation techniques on the resultant biochemical kinetics of immobilised enzymes.
- Full Text:
- Date Issued: 2011
- Authors: Fogel, Ronen
- Date: 2011
- Subjects: Laccase Phenols Biosensors
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4073 , http://hdl.handle.net/10962/d1007166
- Description: Given their widespread effects and distribution in both natural and industrial environments, the monitoring of phenolic compounds is of considerable analytical interest. Electrochemical biosensor technologies, in particular those comprising laccase enzymes, afford many potential benefits to address this analytical need. However, several key factors affecting sensor response currently limit their applicability. This Thesis reports on the fabrication and optimisation of an electrochemical laccase-based biosensor towards the application of the monitoring of phenolic compounds. Selected factors considered to affect sensor response were investigated using the optimised biosensor. These included: electrochemical, biochemical and substrate-dependent factors, which were found to intersect in modulating biosensor response signals. Through the application of transducer-dependent and substrate-dependent parameters, the selective and simultaneous detection of a mixture of different phenolic analytes is successfully demonstrated. This Thesis also investigates the use of Quartz-Crystal Microbalance with Dissipation (QCM-D) technology, an analytical technique that measures physical parameters of thin-film structures, towards the successful monitoring of enzyme immobilisation strategies. These strategies are fundamental to the successful fabrication of biosensors, and the real-time monitoring of immobilised film formations is of considerable research interest. In the studies reported on in this Thesis, QCM-D technology was demonstrated to be an effective complementary technology in the prediction of film immobilisation techniques on the resultant biochemical kinetics of immobilised enzymes.
- Full Text:
- Date Issued: 2011
The role of the mite Orthogalumna terebrantis in the biological control programme for water hyacinth, Eichhornia crassipes, in South Africa
- Authors: Marlin, Danica
- Date: 2011
- Subjects: Water hyacinth -- Biological control -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Mites -- South Africa Mites as biological pest control agents -- South Africa Biological pest control agents -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5762 , http://hdl.handle.net/10962/d1005450
- Description: Water hyacinth (Eichhornia crassipes) is an aquatic macrophyte originating from the Amazon basin. Due to its beautiful appearance it has been introduced into numerous countries across the world as an ornamental pond plant. It was introduced into South Africa in the early 1900s and has since reached pest proportions in many of the country’s fresh water bodies, causing significant economic and ecological losses. It is now considered to be the worst aquatic weed in South Africa. Efforts to control the spread of the weed began in the early 1970s and there have been some successes. Biological control has been used widely as an alternative to mechanical and chemical controls because it is cost-effective, self-sustaining and environmentally friendly. To date, six biological control agents have been introduced onto water hyacinth in South Africa. However, due to factors such as cold winter temperatures and interference from chemical control, the agent populations are occasionally knocked-down and thus the impact of biological control on the weed population is variable. In addition, many South African water systems are highly eutrophic, and in these systems the plant growth may be accelerated to such an extent that the negative impact of the agents’ herbivory is mitigated. One of the agents established on the weed is the galumnid mite Orthogalumna terebrantis, which originates from Uruguay. In South Africa, the mite was initially discovered on two water hyacinth infestations in the Mpumalanga Province in 1989 and it is now established at 17 sites across the country. Many biological control researchers believe that the mite is a good biological control agent but, prior to this thesis, little quantitative data existed to confirm the belief. Thus, this thesis is a post-release evaluation of O. terebrantis in which various aspects of the mite-plant relationship were investigated to determine the efficacy of the mite and thus better understand the role of the mite in the biological control programme of water hyacinth in South Africa. From laboratory experiments, in which mite densities were lower than densities occurring in the field, it was found that water hyacinth growth is largely unaffected by mite herbivory, except possibly at very high mite densities. When grown in high nutrient conditions the growth of the plant is so great that any affect the mite has is nullified. Plant growth is thus more affected by nutrients than by mite herbivory. However, mite feeding was also influenced by water nutrient levels and mite herbivory was greatest on plants grown in high nutrient conditions. The presence of the mite had a positive effect on the performance of the mirid Eccritotarsus catarinensis, such that the interactions of the two agents together had a greater negative impact on the plant’s growth than the individual agents had alone. Furthermore, water hyacinth physiological parameters, such as the plant’s photosynthetic ability, were negatively impacted by the mite, even at the very low mite densities used in the study. Plant growth rate is dependent on photosynthetic ability i.e. the rate of photosynthesis, and thus a decrease in the plant’s photosynthetic ability will eventually be translated into decreased plant growth rates which would ultimately result in the overall reduction of water hyacinth populations. In addition, temperature tolerance studies showed that the mite was tolerant of low temperatures. The mite already occurs at some of the coldest sites in South Africa. Therefore, the mite should be able to establish at all of the water hyacinth infestations in the country, but because it is a poor disperser it is unlikely to establish at new sites without human intervention. It is suggested that the mite be used as an additional biological control agent at sites where it does not yet occur, specifically at cold sites where some of the other, less cold-tolerant, agents have failed to establish. Finally, conditions of where, how many and how often the mite should be distributed to water hyacinth infestation in South Africa are discussed.
- Full Text:
- Date Issued: 2011
- Authors: Marlin, Danica
- Date: 2011
- Subjects: Water hyacinth -- Biological control -- South Africa Aquatic weeds -- South Africa Invasive plants -- South Africa Mites -- South Africa Mites as biological pest control agents -- South Africa Biological pest control agents -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5762 , http://hdl.handle.net/10962/d1005450
- Description: Water hyacinth (Eichhornia crassipes) is an aquatic macrophyte originating from the Amazon basin. Due to its beautiful appearance it has been introduced into numerous countries across the world as an ornamental pond plant. It was introduced into South Africa in the early 1900s and has since reached pest proportions in many of the country’s fresh water bodies, causing significant economic and ecological losses. It is now considered to be the worst aquatic weed in South Africa. Efforts to control the spread of the weed began in the early 1970s and there have been some successes. Biological control has been used widely as an alternative to mechanical and chemical controls because it is cost-effective, self-sustaining and environmentally friendly. To date, six biological control agents have been introduced onto water hyacinth in South Africa. However, due to factors such as cold winter temperatures and interference from chemical control, the agent populations are occasionally knocked-down and thus the impact of biological control on the weed population is variable. In addition, many South African water systems are highly eutrophic, and in these systems the plant growth may be accelerated to such an extent that the negative impact of the agents’ herbivory is mitigated. One of the agents established on the weed is the galumnid mite Orthogalumna terebrantis, which originates from Uruguay. In South Africa, the mite was initially discovered on two water hyacinth infestations in the Mpumalanga Province in 1989 and it is now established at 17 sites across the country. Many biological control researchers believe that the mite is a good biological control agent but, prior to this thesis, little quantitative data existed to confirm the belief. Thus, this thesis is a post-release evaluation of O. terebrantis in which various aspects of the mite-plant relationship were investigated to determine the efficacy of the mite and thus better understand the role of the mite in the biological control programme of water hyacinth in South Africa. From laboratory experiments, in which mite densities were lower than densities occurring in the field, it was found that water hyacinth growth is largely unaffected by mite herbivory, except possibly at very high mite densities. When grown in high nutrient conditions the growth of the plant is so great that any affect the mite has is nullified. Plant growth is thus more affected by nutrients than by mite herbivory. However, mite feeding was also influenced by water nutrient levels and mite herbivory was greatest on plants grown in high nutrient conditions. The presence of the mite had a positive effect on the performance of the mirid Eccritotarsus catarinensis, such that the interactions of the two agents together had a greater negative impact on the plant’s growth than the individual agents had alone. Furthermore, water hyacinth physiological parameters, such as the plant’s photosynthetic ability, were negatively impacted by the mite, even at the very low mite densities used in the study. Plant growth rate is dependent on photosynthetic ability i.e. the rate of photosynthesis, and thus a decrease in the plant’s photosynthetic ability will eventually be translated into decreased plant growth rates which would ultimately result in the overall reduction of water hyacinth populations. In addition, temperature tolerance studies showed that the mite was tolerant of low temperatures. The mite already occurs at some of the coldest sites in South Africa. Therefore, the mite should be able to establish at all of the water hyacinth infestations in the country, but because it is a poor disperser it is unlikely to establish at new sites without human intervention. It is suggested that the mite be used as an additional biological control agent at sites where it does not yet occur, specifically at cold sites where some of the other, less cold-tolerant, agents have failed to establish. Finally, conditions of where, how many and how often the mite should be distributed to water hyacinth infestation in South Africa are discussed.
- Full Text:
- Date Issued: 2011
An investigation into Grade R teachers' experiences of implementing numeracy in Grade R
- Authors: Barnard, Elna
- Date: 2011
- Subjects: Teachers -- South Africa -- Attitudes Numeracy -- Study and teaching (Elementary) -- South Africa Teachers -- Training of -- South Africa Mathematics teachers -- In-service training -- South Africa Early childhood education -- South Africa -- History Early childhood education -- South Africa -- Political aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1855 , http://hdl.handle.net/10962/d1004529
- Description: This research study investigates how selected Grade R teachers implement numeracy in their classrooms, based on their experiences, personal beliefs and perceptions. This study adopts the view that a teacher's practice is not only informed on what she believes about her learners, but also on how she organises her classroom environment and her own teaching practice. However, the teacher cannot be divorced from the political and historical background of Early Childhood Development (ECD), as these factors have an impact on her numeracy implementation. Integrated in this research study is thus not only a comprehensive historical analysis of the historical and political background of ECD, but also an in-depth look at the complex curriculum road the Grade R teacher had to travel over the past twelve years. The aim of this case study is to understand and describe what is happening in Grade R classrooms when numeracy is implemented, as well as identifying possible barriers which Grade R teachers may experience in implementing numeracy. The author utilized an adapted Interactive Qualitative Analysis Framework to explore Grade R teachers' views and experiences. Open-ended focus group interviews were used to develop a framework for individual interviews. This interview framework guided the data collection of nine audio-video tapes of classroom activities and nine semi-structured individual interviews. Analysis of the individual interviews revealed each teacher's understanding as well as her perceptions and needs regarding the implementation of numeracy in her classroom. The transcriptions of the individual interviews were compared to the audio-video tapes of what happened in each classroom. This was done in order to determine whether the teachers' practices were consistent with what they said in the interviews. Paradoxes and inconsistencies were documented. The historical and political analysis of ECD illustrates the complex development of ECD in South Africa over the last few decades. It therefore also highlights and brings to the fore the complex journey that Grade R teachers had to navigate in adapting their practice to ever changing curriculum requirements. The empirical results show that there are inconsistencies between what selected teachers know and believe, and what they are implementing. However, "silent themes" which did not come to the fore in the focus group or individual interviews, were identified in the audiovideo tapes of classroom activities. Also, many "silent themes" indicate that there are numerous concerns, such as lack of proficiency in bridging the gap between theory and practice, regarding the implementation of numeracy in Grade R. It was found that many of the selected Grade R teachers struggle to implement numeracy in their classrooms, as they lack the skills and support to teach numeracy in a Grade R context.
- Full Text:
- Date Issued: 2011
- Authors: Barnard, Elna
- Date: 2011
- Subjects: Teachers -- South Africa -- Attitudes Numeracy -- Study and teaching (Elementary) -- South Africa Teachers -- Training of -- South Africa Mathematics teachers -- In-service training -- South Africa Early childhood education -- South Africa -- History Early childhood education -- South Africa -- Political aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1855 , http://hdl.handle.net/10962/d1004529
- Description: This research study investigates how selected Grade R teachers implement numeracy in their classrooms, based on their experiences, personal beliefs and perceptions. This study adopts the view that a teacher's practice is not only informed on what she believes about her learners, but also on how she organises her classroom environment and her own teaching practice. However, the teacher cannot be divorced from the political and historical background of Early Childhood Development (ECD), as these factors have an impact on her numeracy implementation. Integrated in this research study is thus not only a comprehensive historical analysis of the historical and political background of ECD, but also an in-depth look at the complex curriculum road the Grade R teacher had to travel over the past twelve years. The aim of this case study is to understand and describe what is happening in Grade R classrooms when numeracy is implemented, as well as identifying possible barriers which Grade R teachers may experience in implementing numeracy. The author utilized an adapted Interactive Qualitative Analysis Framework to explore Grade R teachers' views and experiences. Open-ended focus group interviews were used to develop a framework for individual interviews. This interview framework guided the data collection of nine audio-video tapes of classroom activities and nine semi-structured individual interviews. Analysis of the individual interviews revealed each teacher's understanding as well as her perceptions and needs regarding the implementation of numeracy in her classroom. The transcriptions of the individual interviews were compared to the audio-video tapes of what happened in each classroom. This was done in order to determine whether the teachers' practices were consistent with what they said in the interviews. Paradoxes and inconsistencies were documented. The historical and political analysis of ECD illustrates the complex development of ECD in South Africa over the last few decades. It therefore also highlights and brings to the fore the complex journey that Grade R teachers had to navigate in adapting their practice to ever changing curriculum requirements. The empirical results show that there are inconsistencies between what selected teachers know and believe, and what they are implementing. However, "silent themes" which did not come to the fore in the focus group or individual interviews, were identified in the audiovideo tapes of classroom activities. Also, many "silent themes" indicate that there are numerous concerns, such as lack of proficiency in bridging the gap between theory and practice, regarding the implementation of numeracy in Grade R. It was found that many of the selected Grade R teachers struggle to implement numeracy in their classrooms, as they lack the skills and support to teach numeracy in a Grade R context.
- Full Text:
- Date Issued: 2011
Women's empowerment in the post-1994 Rwanda: the case study of Mayaga Region
- Authors: Hategekimana, Celestin
- Date: 2011
- Subjects: Women in development -- Rwanda , Women -- Rwanda -- Social conditions , Women -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9068 , http://hdl.handle.net/10948/1314 , Women in development -- Rwanda , Women -- Rwanda -- Social conditions , Women -- Economic conditions
- Description: This research looks at the process of women’s empowerment in post- 1994 Rwanda, with special focus on twelve cooperatives working in Mayaga region and the way these cooperatives empower women, their households and the community at large. Traditional Rwandan society has been always bound by patriarchy which has not valued the reproductive roles of women as economically productive in their households and the society as a whole. On the one hand, this understanding was reversed in the post-1994 Rwanda by the commitment of the government to gender equality at the highest level of political leadership through progressive policies and legislation. On the other hand, in Mayaga region, cooperatives brought about socio-economic development and changed relationships of gender and power in a patriarchal post-conflict society. The findings from cooperatives in Mayaga region show that to prevent women from reaching their full potential is economic folly. If women are empowered, they can generate important development outcomes such as improved health, education, income levels and conflict resolution. The findings further indicate how women’s empowerment is determined by the livelihood strategies women adopt themselves to respond to their vulnerability, and by the ways in which they express their agency in making a living in a sustainable way, with the available community assets that they have access to (financial, social, human, natural and physical). This research highlights that the accessibility of the community assets used by women in Mayaga region and in Rwanda as a whole is also determined by policies, institutions and processes that are able to influence their livelihoods positively.
- Full Text:
- Date Issued: 2011
- Authors: Hategekimana, Celestin
- Date: 2011
- Subjects: Women in development -- Rwanda , Women -- Rwanda -- Social conditions , Women -- Economic conditions
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9068 , http://hdl.handle.net/10948/1314 , Women in development -- Rwanda , Women -- Rwanda -- Social conditions , Women -- Economic conditions
- Description: This research looks at the process of women’s empowerment in post- 1994 Rwanda, with special focus on twelve cooperatives working in Mayaga region and the way these cooperatives empower women, their households and the community at large. Traditional Rwandan society has been always bound by patriarchy which has not valued the reproductive roles of women as economically productive in their households and the society as a whole. On the one hand, this understanding was reversed in the post-1994 Rwanda by the commitment of the government to gender equality at the highest level of political leadership through progressive policies and legislation. On the other hand, in Mayaga region, cooperatives brought about socio-economic development and changed relationships of gender and power in a patriarchal post-conflict society. The findings from cooperatives in Mayaga region show that to prevent women from reaching their full potential is economic folly. If women are empowered, they can generate important development outcomes such as improved health, education, income levels and conflict resolution. The findings further indicate how women’s empowerment is determined by the livelihood strategies women adopt themselves to respond to their vulnerability, and by the ways in which they express their agency in making a living in a sustainable way, with the available community assets that they have access to (financial, social, human, natural and physical). This research highlights that the accessibility of the community assets used by women in Mayaga region and in Rwanda as a whole is also determined by policies, institutions and processes that are able to influence their livelihoods positively.
- Full Text:
- Date Issued: 2011
Development and testing of liposome encapsulated cyclic dipeptides
- Authors: Kilian, Gareth
- Date: 2011
- Subjects: Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10136 , http://hdl.handle.net/10948/1397 , Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Description: Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).
- Full Text:
- Date Issued: 2011
- Authors: Kilian, Gareth
- Date: 2011
- Subjects: Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10136 , http://hdl.handle.net/10948/1397 , Peptide antibiotics , Peptide drugs -- Therapeutic use , Peptides -- Synthesis , Antibacterial agents -- Therapeutic use -- Testing , Cyclic peptides , Liposomes
- Description: Cyclic dipeptides have been well characterized for their multitude of biological activities, including antimicrobial and anticancer activities. Cyclo(His-Gly) and cyclo(His-Ala) have also recently been shown to possess significant anticancer activity against a range of cell lines, despite the limitations of these two molecules with respect to their physicochemical properties. Low Log P results in poor cell permeability which can often be problematic for drugs with intracellular mechanisms of action. It can also results in poor biodistribution, and theoretical Log P values for cyclo(His-Gly) and cyclo(His-Ala) were extremely low making them ideal candidates for inclusion into a nanoparticulate drug delivery system. The aim of this study was therefore to formulate and evaluate liposome-encapsulated cyclic dipeptides that increase the tumour-suppressive actions of the cyclic dipeptides, while showing a high degree of specificity for tumour cells. While liposomes are relatively simple to prepare, inter batch variation, low encapsulation and poor stability are often problematic in their production and this has lead to very few liposomal products on the market. This study aimed at using a comprehensive statistical methodology in optimizing liposome formulations encapsulating cyclo(His-Gly) and cyclo(His-Ala). Initial screening of potential factors was conducted using a 25-1 fractional factorial design. This design made use of two levels for each of the five factors and abbreviated the design to minimize runs. Although not much information is provided by these types of designs, the design was sufficient in identifying two critical factors that would be studies further in a more robust design. The two factors selected, based on the screening study, were cholesterol and stearylamine content. These two factors were then used in designing a response surface methodology (RSM) design making use of a central composite rotatable vii design (CCRD) at five levels (-1.5, -1, 0, 1, 1.5) for each factor in order to better understand the design space. Various factors influenced the measured responses of encapsulation efficiency, zeta potential, polydispersity index, cellular uptake and leakage, but most notable were the adverse effects of increasing stearylamine levels on encapsulations efficiency and cholesterol levels on leakage for both cyclo(His-Gly) and cyclo(His-Ala) liposomes. Optimized formulations were derived from the data and prepared. Fair correlation between the predicted and measured responses was obtained. The cytotoxic activity of the encapsulated cyclic dipeptides were assessed against HeLa and MCF-7 cells and found to have limited improvement in activity. However, modification of the polyethylene glycol (PEG) grafted to the liposome surface in order to target folate receptors showed good benefit in significantly decreasing the IC50 values recorded in all cells lines tested, particularly low folate HeLa cells with the lowest IC50 being recorded as 0.0962 mM for folate targeted cyclo(His-Ala). The results therefore indicate that hydrophilic cyclic dipeptides are ideal candidates for inclusion into targeted drug delivery systems such as liposomes. Key words: Liposomes, cyclo(His-Gly), cyclo(His-Ala), cyclic dipeptides, HeLa, MCF-7, folate receptors, factorial design, response surface methodology (RSM), central composite rotatable design (CCRD).
- Full Text:
- Date Issued: 2011
Performance evaluation of buildings in educational institutions: a case of Universities in South-East Nigeria
- Authors: Okolie, Kevin Chuks
- Date: 2011
- Subjects: Buildings -- Nigeria -- Evaluation , College buildings -- Nigeria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9683 , http://hdl.handle.net/10948/1423 , Buildings -- Nigeria -- Evaluation , College buildings -- Nigeria
- Description: Buildings constitute a substantial percentage of most educational institutions' assets, user needs and operating costs. The performance level of this resource is therefore very critical to educational effectiveness. However, despite the crucial role of this resource in the education and construction sectors of the economy, evaluation of building performance is not a mainstream activity in Africa, particularly Nigeria. Presently, there is limited or no research/data in Nigeria to assess how extensively the use of or lack of building performance evaluation techniques affect teaching, learning spaces and overall organisational performance. The aim of this research was to develop an appropriate model for building performance evaluation in higher education institutions based on performance indicators, for improved awareness, understanding and practice. The research primarily focused on "user needs/requirements" within the organisational context. The methodology employed in the study included a review of the relevant literature and multiple case-studies conducted on four Federal Government universities in South East Nigeria. The target universities constituted the units of analyses and therefore provided opportunity for in-depth examination of the links between users, building facilities and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically positivist. However, some qualitative aspects of data were relevant to the study and therefore used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources. The sampling technique was sequential involving both purposive and stratified random sampling. The study reveals apparent lack of a systematic mechanism for evaluating the success or performance of completed and occupied buildings and so the interaction between users and buildings did not add value to learning and working experiences in the target institutions. The bespoke methodology and conceptual process model developed in this research constitute an innovative and pioneering contribution to building performance evaluation as a developing field of knowledge. The study has established a basic level of awareness and understanding among construction practitioners that building performance evaluation can be used as a tool for delivering strategic objectives in the management of educational buildings. The study strongly advocates the inclusion of building performance evaluation as part of the building procurement process. The proposed model in the study provides a useful guide needed by the institutions to navigate to future competitive success in higher education built asset/facilities management.
- Full Text:
- Date Issued: 2011
- Authors: Okolie, Kevin Chuks
- Date: 2011
- Subjects: Buildings -- Nigeria -- Evaluation , College buildings -- Nigeria
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9683 , http://hdl.handle.net/10948/1423 , Buildings -- Nigeria -- Evaluation , College buildings -- Nigeria
- Description: Buildings constitute a substantial percentage of most educational institutions' assets, user needs and operating costs. The performance level of this resource is therefore very critical to educational effectiveness. However, despite the crucial role of this resource in the education and construction sectors of the economy, evaluation of building performance is not a mainstream activity in Africa, particularly Nigeria. Presently, there is limited or no research/data in Nigeria to assess how extensively the use of or lack of building performance evaluation techniques affect teaching, learning spaces and overall organisational performance. The aim of this research was to develop an appropriate model for building performance evaluation in higher education institutions based on performance indicators, for improved awareness, understanding and practice. The research primarily focused on "user needs/requirements" within the organisational context. The methodology employed in the study included a review of the relevant literature and multiple case-studies conducted on four Federal Government universities in South East Nigeria. The target universities constituted the units of analyses and therefore provided opportunity for in-depth examination of the links between users, building facilities and organisational processes as established in the literature review. Epistemologically, the research is objectivist and paradigmically positivist. However, some qualitative aspects of data were relevant to the study and therefore used in a complementary manner. The case approach utilized mixed methods by applying a range of data collection techniques and evidence from multiple sources. The sampling technique was sequential involving both purposive and stratified random sampling. The study reveals apparent lack of a systematic mechanism for evaluating the success or performance of completed and occupied buildings and so the interaction between users and buildings did not add value to learning and working experiences in the target institutions. The bespoke methodology and conceptual process model developed in this research constitute an innovative and pioneering contribution to building performance evaluation as a developing field of knowledge. The study has established a basic level of awareness and understanding among construction practitioners that building performance evaluation can be used as a tool for delivering strategic objectives in the management of educational buildings. The study strongly advocates the inclusion of building performance evaluation as part of the building procurement process. The proposed model in the study provides a useful guide needed by the institutions to navigate to future competitive success in higher education built asset/facilities management.
- Full Text:
- Date Issued: 2011
Effect of nanoparticles on the photophysicochemical behaviour of metallophthalocyanines
- Moeno, Sharon Keitumetse Gail Mpheletso
- Authors: Moeno, Sharon Keitumetse Gail Mpheletso
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Nanoparticles Photochemistry Quantum dots
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4310 , http://hdl.handle.net/10962/d1004968
- Description: The synthesis, spectroscopic characterization, and studies of the photophysicochemical behaviour of selective anionic, cationic and neutral metallophthallocyanine (MPc) complexes were carried out and the results are presented herein. Studies on the effect of the central metal ion, the solvent used and the presence of nanoparticles on the photophysicochemical properties were conducted. The findings showed that the photophysicochemical parameters were mostly enhanced in the presence of central metal ions of high atomic numbers and also in the presence of nanoparticles. It was also observed that solvents that encouraged the monomericity of the MPc complexes also lead to improved photophysical and photochemical behaviour. CdTe quantum dots (QDs) stabilized with mercaptocarbonic acids were also observed to cause stimulated emission of the MPcs through Förster resonance energy transfer (FRET) thus acting as energy donors while the respective MPc acted as energy acceptors in all the FRET studies. FRET was observed following the photoexcitation of QDs for all monomeric anionic MPcs but it was also shown to occur for some cationic MPcs in organic media. Both the substituent and solvent used were found to exert a strong influence on the occurrence of FRET. Other cationic MPcs however showed different behaviour in the presence of the meraptocarbonic stabilized CdTe QDs; with the cationic porphyrazine giving clear indications of Pc ring reduction. The rest of the cationic MPcs did not give clear evidence of Pc ring reduction, instead they showed signs of aggregate formation possibly from the assembly of electrostatic ion pair complexes which could result in reduction of the quaternized pyridinium ring of the substituent. Both the QDs and the MPc complex emission spectra were significantly quenched for each in the presence of the other. Stern-Volmer quenching studies indicated that both static and dynamic quenching of the QDs in the presence of MPcs took place. The fluorescence lifetimes of the mercaptopropionic acid (MPA) capped CdTe QDs in the presence of various MPc complexes showed quenching of mostly the longer lifetimes of the QDs in the presence of MPcs suggesting that the surface defects and states are involved in the interaction of the QDs and MPcs. An MPc complex terminating in thio tethers was employed in the conjugation to AuNPs. Spectroscopic and microscopic studies confirmed the formation of the MPc-AuNP conjugate which was also shown to exhibit improved photophysicochemical properties compared to the free MPc.
- Full Text:
- Date Issued: 2011
- Authors: Moeno, Sharon Keitumetse Gail Mpheletso
- Date: 2011 , 2011-03-30
- Subjects: Phthalocyanines Nanoparticles Photochemistry Quantum dots
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4310 , http://hdl.handle.net/10962/d1004968
- Description: The synthesis, spectroscopic characterization, and studies of the photophysicochemical behaviour of selective anionic, cationic and neutral metallophthallocyanine (MPc) complexes were carried out and the results are presented herein. Studies on the effect of the central metal ion, the solvent used and the presence of nanoparticles on the photophysicochemical properties were conducted. The findings showed that the photophysicochemical parameters were mostly enhanced in the presence of central metal ions of high atomic numbers and also in the presence of nanoparticles. It was also observed that solvents that encouraged the monomericity of the MPc complexes also lead to improved photophysical and photochemical behaviour. CdTe quantum dots (QDs) stabilized with mercaptocarbonic acids were also observed to cause stimulated emission of the MPcs through Förster resonance energy transfer (FRET) thus acting as energy donors while the respective MPc acted as energy acceptors in all the FRET studies. FRET was observed following the photoexcitation of QDs for all monomeric anionic MPcs but it was also shown to occur for some cationic MPcs in organic media. Both the substituent and solvent used were found to exert a strong influence on the occurrence of FRET. Other cationic MPcs however showed different behaviour in the presence of the meraptocarbonic stabilized CdTe QDs; with the cationic porphyrazine giving clear indications of Pc ring reduction. The rest of the cationic MPcs did not give clear evidence of Pc ring reduction, instead they showed signs of aggregate formation possibly from the assembly of electrostatic ion pair complexes which could result in reduction of the quaternized pyridinium ring of the substituent. Both the QDs and the MPc complex emission spectra were significantly quenched for each in the presence of the other. Stern-Volmer quenching studies indicated that both static and dynamic quenching of the QDs in the presence of MPcs took place. The fluorescence lifetimes of the mercaptopropionic acid (MPA) capped CdTe QDs in the presence of various MPc complexes showed quenching of mostly the longer lifetimes of the QDs in the presence of MPcs suggesting that the surface defects and states are involved in the interaction of the QDs and MPcs. An MPc complex terminating in thio tethers was employed in the conjugation to AuNPs. Spectroscopic and microscopic studies confirmed the formation of the MPc-AuNP conjugate which was also shown to exhibit improved photophysicochemical properties compared to the free MPc.
- Full Text:
- Date Issued: 2011
Exploring ways of assisting Lesotho educators to offer care and support to children orphaned and rendered vulnerable by HIV and AIDS
- Authors: Ntaote, Grace Makeletso
- Date: 2011
- Subjects: Orphans -- Developing Countries -- Social conditions , HIV infections
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9503 , http://hdl.handle.net/10948/1320 , Orphans -- Developing Countries -- Social conditions , HIV infections
- Description: The HIV and AIDS pandemic has resulted in 14 million children being orphaned worldwide. In Lesotho alone, where this study was carried out, there are about 180 000 of these children (UNAIDS, 2007). Teachers, especially in Lesotho‘s primary schools need to be equipped to better deal with the challenges that result from having these children in their classrooms. At the Lesotho College of Education, where I have worked for 12 years as a teacher educator, pre-service and in-service student teachers are not trained to offer care and support to orphans and vulnerable children. They experience problems in the classroom emanating from the needs of these children. This study followed an action research design to find ways to support teachers to better deal with the issues they face as a result of having orphans and vulnerable children in their classes. Using a qualitative approach, educators perceptions, feelings, attitudes and experiences in dealing with orphans and vulnerable children in their schools were identified, and it became apparent that educators were negatively affected on a personal and professional level. It was concluded that the development of resilience in educators would help them to better cope with orphans and vulnerable children in their classes. The chosen intervention Resilient Educators Programme (REds) was implemented and evaluated and findings revealed that it was beneficial in increasing educator resilience. Recommendations, based on the findings of the study, were made for future teacher education in this area.
- Full Text:
- Date Issued: 2011
- Authors: Ntaote, Grace Makeletso
- Date: 2011
- Subjects: Orphans -- Developing Countries -- Social conditions , HIV infections
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9503 , http://hdl.handle.net/10948/1320 , Orphans -- Developing Countries -- Social conditions , HIV infections
- Description: The HIV and AIDS pandemic has resulted in 14 million children being orphaned worldwide. In Lesotho alone, where this study was carried out, there are about 180 000 of these children (UNAIDS, 2007). Teachers, especially in Lesotho‘s primary schools need to be equipped to better deal with the challenges that result from having these children in their classrooms. At the Lesotho College of Education, where I have worked for 12 years as a teacher educator, pre-service and in-service student teachers are not trained to offer care and support to orphans and vulnerable children. They experience problems in the classroom emanating from the needs of these children. This study followed an action research design to find ways to support teachers to better deal with the issues they face as a result of having orphans and vulnerable children in their classes. Using a qualitative approach, educators perceptions, feelings, attitudes and experiences in dealing with orphans and vulnerable children in their schools were identified, and it became apparent that educators were negatively affected on a personal and professional level. It was concluded that the development of resilience in educators would help them to better cope with orphans and vulnerable children in their classes. The chosen intervention Resilient Educators Programme (REds) was implemented and evaluated and findings revealed that it was beneficial in increasing educator resilience. Recommendations, based on the findings of the study, were made for future teacher education in this area.
- Full Text:
- Date Issued: 2011
The druggable antimalarial target 1-deoxy-D-xylulose-5-phosphate reductoisomerase: purfication, kinetic characterization and inhibition studies
- Authors: Goble, Jessica Leigh
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Drug development Plasmodium falciparum -- Purification Plasmodium falciparum -- Inhibitors Enzyme kinetics Malaria -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3949 , http://hdl.handle.net/10962/d1004008
- Description: Plasmodium falciparum 1–deoxy–D–xylulose–5 phosphatereductoisomerase (PfDXR) plays a role in isoprenoid biosynthesis in the malaria parasite and is absent in the human host, making this parasite enzyme an attractive target for antimalarial drug design. To characterize PfDXR, it is necessary to produce large quantities of the enzyme in a soluble and functional form. However, the over–production of malarial proteins in prokaryotic host systems often results in the formation of truncated proteins or insoluble protein aggregates. A heterologous expression system was developed for the production of active PfDXR using codon harmonization and tight control of expression in the presence of lac repressor. Yields of up to 2 mg/l of enzyme were reported using the optimised expression system, which is 8 to 10– fold greater than previously reported yields. The kinetic parameters Km, Vmax and kcat were determined for PfDXR; values reported in this study were consistent with those reported in the literature for other DXR enzymes. A three–dimensional model of the malarial drug target protein PfDXR was generated, and validated using structure–checking programs and protein docking studies. Structural and functional features unique to PfDXR were identified using the model and comparative sequence analyses with apicomplexan and non–apicomplexan DXR proteins. Residues Val44 and Asn45, essential for NADPH binding; and catalytic hatch residues Lys224 and Lys226, which are unique to the species of Plasmodium, were mutated to resemble those of E. coli DXR. Interestingly,these mutations resulted in significant reductions in substrate affinity, when compared to the unmutated PfDXR. Mutant enzymes PfDXR(VN43,44AG) and PfDXR(KK224,226NS) also demonstrated a decreased ability to turnover substrate by 4–fold and 2–fold respectively. This study indicates a difference in the role of the catalytic hatch of PfDXR with regards to the way in which it captures substrates. The study also highlights subtle differences in cofactor binding to PfDXR, compared with the well characterized EcDXR enzyme. The validated PfDXR model was also used to develop a novel efficient in silico screening method for potential tool compounds for use in the rational design of novel DXR inhibitors. Following in silico screening of 46 potential DXR inhibitors, a two–tiered in vitro screening approach was undertaken. DXR inhibition was assessed for the 46 novel compounds using an NADPH– ependant DXP enzyme inhibition assay and antimalarial potential was assessed using P.falciparum–infected erythrocyte growth assays. Select compounds were tested in human cells in order to determine whether they were toxic to the host. From the parallel in silico and in vitro drug screening, it was evident that only a single compound demonstrated reasonable potential binding to DXR (determined using in silico docking), inhibited DXR in vitro and inhibited P. falciparum growth, without being toxic to human cells. Its potential as a lead compound in antimalarial drug development is therefore feasible. Two outcomes were evident from this work. Firstly, analogues of known antimalarial natural products can be screened against malaria, which may then lead towards the rational design of novel compounds that are effective against a specific antimalarial drug target enzyme, such as PfDXR. Secondly, the rational design of novel compounds against a specific antimalarial drug target enzyme can be untaken by adopting a coupled in silico and in vitro approach to drug discovery.
- Full Text:
- Date Issued: 2011
- Authors: Goble, Jessica Leigh
- Date: 2011
- Subjects: Antimalarials -- Development Plasmodium falciparum Drug development Plasmodium falciparum -- Purification Plasmodium falciparum -- Inhibitors Enzyme kinetics Malaria -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3949 , http://hdl.handle.net/10962/d1004008
- Description: Plasmodium falciparum 1–deoxy–D–xylulose–5 phosphatereductoisomerase (PfDXR) plays a role in isoprenoid biosynthesis in the malaria parasite and is absent in the human host, making this parasite enzyme an attractive target for antimalarial drug design. To characterize PfDXR, it is necessary to produce large quantities of the enzyme in a soluble and functional form. However, the over–production of malarial proteins in prokaryotic host systems often results in the formation of truncated proteins or insoluble protein aggregates. A heterologous expression system was developed for the production of active PfDXR using codon harmonization and tight control of expression in the presence of lac repressor. Yields of up to 2 mg/l of enzyme were reported using the optimised expression system, which is 8 to 10– fold greater than previously reported yields. The kinetic parameters Km, Vmax and kcat were determined for PfDXR; values reported in this study were consistent with those reported in the literature for other DXR enzymes. A three–dimensional model of the malarial drug target protein PfDXR was generated, and validated using structure–checking programs and protein docking studies. Structural and functional features unique to PfDXR were identified using the model and comparative sequence analyses with apicomplexan and non–apicomplexan DXR proteins. Residues Val44 and Asn45, essential for NADPH binding; and catalytic hatch residues Lys224 and Lys226, which are unique to the species of Plasmodium, were mutated to resemble those of E. coli DXR. Interestingly,these mutations resulted in significant reductions in substrate affinity, when compared to the unmutated PfDXR. Mutant enzymes PfDXR(VN43,44AG) and PfDXR(KK224,226NS) also demonstrated a decreased ability to turnover substrate by 4–fold and 2–fold respectively. This study indicates a difference in the role of the catalytic hatch of PfDXR with regards to the way in which it captures substrates. The study also highlights subtle differences in cofactor binding to PfDXR, compared with the well characterized EcDXR enzyme. The validated PfDXR model was also used to develop a novel efficient in silico screening method for potential tool compounds for use in the rational design of novel DXR inhibitors. Following in silico screening of 46 potential DXR inhibitors, a two–tiered in vitro screening approach was undertaken. DXR inhibition was assessed for the 46 novel compounds using an NADPH– ependant DXP enzyme inhibition assay and antimalarial potential was assessed using P.falciparum–infected erythrocyte growth assays. Select compounds were tested in human cells in order to determine whether they were toxic to the host. From the parallel in silico and in vitro drug screening, it was evident that only a single compound demonstrated reasonable potential binding to DXR (determined using in silico docking), inhibited DXR in vitro and inhibited P. falciparum growth, without being toxic to human cells. Its potential as a lead compound in antimalarial drug development is therefore feasible. Two outcomes were evident from this work. Firstly, analogues of known antimalarial natural products can be screened against malaria, which may then lead towards the rational design of novel compounds that are effective against a specific antimalarial drug target enzyme, such as PfDXR. Secondly, the rational design of novel compounds against a specific antimalarial drug target enzyme can be untaken by adopting a coupled in silico and in vitro approach to drug discovery.
- Full Text:
- Date Issued: 2011
Core self-evaluations, racial evaluation and learning amongst Zulu students at the university of Zululand
- Authors: Dodd Nicole Marguerite
- Date: 2011
- Subjects: Zulu (African people) -- Ethnic identity , Self-evaluation , Ethnicity
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9879 , http://hdl.handle.net/10948/d1008398 , Zulu (African people) -- Ethnic identity , Self-evaluation , Ethnicity
- Description: Core Self-Evaluations [CSE] are a person’s estimation of his/her own worth and ability (Judge & Scott 2009). This in turn, is related to Racial Evaluation which is a person’s internal evaluation of his/her racial identity (Diller, 2010). The Employment Equity Act (55 of 1998) makes provision for the employment of equity candidates who can acquire skills in a reasonable amount of time. This requires individuals to be able to learn and then achieve in outcomes-based assessment. Core Self-Evaluations and Racial Evaluation can have an impact on how individuals perceive themselves, and how they perform in education, training and development (Hanley & Noblit, 2009). This study explored the relationship between Core Self-Evaluation, Racial Evaluation, Learning and Outcomes-Based Assessment using an experimental design. The Core Self-Evaluation scores in this study (n=230) were consistent with levels found internationally (Broucek, 2005). There was positive Racial Evaluation, with a relationship existing between Racial Evaluation and Core Self-Evaluations. This means that part of a person’s identity as an individual is related to Racial Evaluation, with that Racial Evaluation being positive amongst young Zulu students at the University of Zululand. There was a statistically significant, but small correlation between Learning and Core Self- Evaluation and a relationship was also found between CSE and Outcomes-Based Assessment results. When Core Self-Evaluation is higher, Learning tends to be more likely. The same pattern does not hold for Outcomes-Based Assessment results. Among Zulu students, lower CSE is linked to improved Outcomes-Based Assessment results. Racial Evaluation has a small relationship with CSE. However, efforts to remedy apartheid may be directed towards socio-economic development and need not focus on boosting Racial Evaluation when it comes to young Zulu adults.
- Full Text:
- Date Issued: 2011
- Authors: Dodd Nicole Marguerite
- Date: 2011
- Subjects: Zulu (African people) -- Ethnic identity , Self-evaluation , Ethnicity
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9879 , http://hdl.handle.net/10948/d1008398 , Zulu (African people) -- Ethnic identity , Self-evaluation , Ethnicity
- Description: Core Self-Evaluations [CSE] are a person’s estimation of his/her own worth and ability (Judge & Scott 2009). This in turn, is related to Racial Evaluation which is a person’s internal evaluation of his/her racial identity (Diller, 2010). The Employment Equity Act (55 of 1998) makes provision for the employment of equity candidates who can acquire skills in a reasonable amount of time. This requires individuals to be able to learn and then achieve in outcomes-based assessment. Core Self-Evaluations and Racial Evaluation can have an impact on how individuals perceive themselves, and how they perform in education, training and development (Hanley & Noblit, 2009). This study explored the relationship between Core Self-Evaluation, Racial Evaluation, Learning and Outcomes-Based Assessment using an experimental design. The Core Self-Evaluation scores in this study (n=230) were consistent with levels found internationally (Broucek, 2005). There was positive Racial Evaluation, with a relationship existing between Racial Evaluation and Core Self-Evaluations. This means that part of a person’s identity as an individual is related to Racial Evaluation, with that Racial Evaluation being positive amongst young Zulu students at the University of Zululand. There was a statistically significant, but small correlation between Learning and Core Self- Evaluation and a relationship was also found between CSE and Outcomes-Based Assessment results. When Core Self-Evaluation is higher, Learning tends to be more likely. The same pattern does not hold for Outcomes-Based Assessment results. Among Zulu students, lower CSE is linked to improved Outcomes-Based Assessment results. Racial Evaluation has a small relationship with CSE. However, efforts to remedy apartheid may be directed towards socio-economic development and need not focus on boosting Racial Evaluation when it comes to young Zulu adults.
- Full Text:
- Date Issued: 2011
An assessment of the implementation of continuing professional development programmes for primary school teachers in Malawi: a case of Zomba rural education district
- Authors: Selemani-Meke, Elizabeth
- Date: 2011
- Subjects: Primary school teachers -- Malawi , Teachers -- Vocational guidance -- Malawi , Teachers -- Development -- Zimbabwe , Teachers -- Education (Primary) -- Malawi , Teachers -- Economic conditions , Teachers -- In-service training -- Malawi , Teachers -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16178 , http://hdl.handle.net/10353/501 , Primary school teachers -- Malawi , Teachers -- Vocational guidance -- Malawi , Teachers -- Development -- Zimbabwe , Teachers -- Education (Primary) -- Malawi , Teachers -- Economic conditions , Teachers -- In-service training -- Malawi , Teachers -- Social conditions
- Description: This study assessed the implementation of Continuing Professional Development (CPD) Programmes for primary school teachers in Zomba Rural Education District in Malawi. The study arose from a concern that, despite the Government of Malawi putting in place structures to facilitate the implementation of CPD for primary school teachers, research has shown that teachers have not improved their classroom practice. As a result, there has been poor learner performance at all levels of the primary education system to the extent that learners scored the lowest in the 2005 international examinations for the Southern Africa Development Community. From the literature, it appears that no thorough and conclusive studies to look into the issues behind the implementation of CPD programmes in Malawi have been conducted. Hence the researcher was motivated to assess how the CPD programmes are implemented with the view to explore better ways of implementing CPD programmes for teachers that can result in teacher change. The study was placed within the post-positivism paradigm and used a mixed method research design that incorporated concurrent procedures in the collection, analysis and interpretation of the data. Questionnaires were used to collect quantitative data while qualitative data were collected through interviews, focus group discussions, CPD observations and document analysis. A total of 798 teachers filled the questionnaires. This figure represented 47% of the total number of teachers in the district. The researcher conducted 34 focus group discussions with teachers from various schools. She also held interviews with 34 head teachers and CPD programme facilitators (12 Primary Education Advisors and 3 CPD facilitators from organizations). Other interviews were held with the District Education Manager, the Coordinating Primary Education Advisor, the Coordinator of the New Curriculum, and the Coordinator for the Department of Teacher Education and Development. Further, the researcher made 3 CPD observations. The study revealed weaknesses in the implementation of CPD programmes for teachers in the district. Generally the study noted that there was much emphasis on the transmissive model of CPD implementation, to the neglect of transitional and transformative models such that the personal, social and occupational aspects of professional learning were not holistically considered in the programme designs. Specifically, the duration of the programmes was found to be inadequate for meaningful assimilation of new knowledge and skills; the expertise of facilitators was sometimes questionable; and the use of the cascade mode left teachers unsure and with knowledge gaps. Further, the study noted that the monitoring and support mechanisms for the programmes were weak; the consultation processes for teacher inputs in the CPD programme designs were dismal; and the welfare of teachers at the CPD venues was poorly handled.. At school level the study revealed that the teaching and learning environment compounded the problem of teachers’ difficulty in implementing what they learnt from CPD training. Large classes, inadequate teachers, lack of teaching and learning resources, limited infrastructure, lack of accommodation for teachers, lack of support from colleagues and learner absenteeism were some of the factors hindering implementation of CPD programmes at school level. The study has put forth recommendations for the effective implementation of CPD programmes for teachers in the district. Furthermore, based on the findings of the study and an extensive literature search, the researcher has suggested an alternative model for CPD implementation that can result in teacher change. Overall there is need for collaborative effort among stakeholders in education to ensure effective delivery of CPDs and their subsequent translation into practice at classroom level.
- Full Text:
- Date Issued: 2011
- Authors: Selemani-Meke, Elizabeth
- Date: 2011
- Subjects: Primary school teachers -- Malawi , Teachers -- Vocational guidance -- Malawi , Teachers -- Development -- Zimbabwe , Teachers -- Education (Primary) -- Malawi , Teachers -- Economic conditions , Teachers -- In-service training -- Malawi , Teachers -- Social conditions
- Language: English
- Type: Thesis , Doctoral , PhD (Education)
- Identifier: vital:16178 , http://hdl.handle.net/10353/501 , Primary school teachers -- Malawi , Teachers -- Vocational guidance -- Malawi , Teachers -- Development -- Zimbabwe , Teachers -- Education (Primary) -- Malawi , Teachers -- Economic conditions , Teachers -- In-service training -- Malawi , Teachers -- Social conditions
- Description: This study assessed the implementation of Continuing Professional Development (CPD) Programmes for primary school teachers in Zomba Rural Education District in Malawi. The study arose from a concern that, despite the Government of Malawi putting in place structures to facilitate the implementation of CPD for primary school teachers, research has shown that teachers have not improved their classroom practice. As a result, there has been poor learner performance at all levels of the primary education system to the extent that learners scored the lowest in the 2005 international examinations for the Southern Africa Development Community. From the literature, it appears that no thorough and conclusive studies to look into the issues behind the implementation of CPD programmes in Malawi have been conducted. Hence the researcher was motivated to assess how the CPD programmes are implemented with the view to explore better ways of implementing CPD programmes for teachers that can result in teacher change. The study was placed within the post-positivism paradigm and used a mixed method research design that incorporated concurrent procedures in the collection, analysis and interpretation of the data. Questionnaires were used to collect quantitative data while qualitative data were collected through interviews, focus group discussions, CPD observations and document analysis. A total of 798 teachers filled the questionnaires. This figure represented 47% of the total number of teachers in the district. The researcher conducted 34 focus group discussions with teachers from various schools. She also held interviews with 34 head teachers and CPD programme facilitators (12 Primary Education Advisors and 3 CPD facilitators from organizations). Other interviews were held with the District Education Manager, the Coordinating Primary Education Advisor, the Coordinator of the New Curriculum, and the Coordinator for the Department of Teacher Education and Development. Further, the researcher made 3 CPD observations. The study revealed weaknesses in the implementation of CPD programmes for teachers in the district. Generally the study noted that there was much emphasis on the transmissive model of CPD implementation, to the neglect of transitional and transformative models such that the personal, social and occupational aspects of professional learning were not holistically considered in the programme designs. Specifically, the duration of the programmes was found to be inadequate for meaningful assimilation of new knowledge and skills; the expertise of facilitators was sometimes questionable; and the use of the cascade mode left teachers unsure and with knowledge gaps. Further, the study noted that the monitoring and support mechanisms for the programmes were weak; the consultation processes for teacher inputs in the CPD programme designs were dismal; and the welfare of teachers at the CPD venues was poorly handled.. At school level the study revealed that the teaching and learning environment compounded the problem of teachers’ difficulty in implementing what they learnt from CPD training. Large classes, inadequate teachers, lack of teaching and learning resources, limited infrastructure, lack of accommodation for teachers, lack of support from colleagues and learner absenteeism were some of the factors hindering implementation of CPD programmes at school level. The study has put forth recommendations for the effective implementation of CPD programmes for teachers in the district. Furthermore, based on the findings of the study and an extensive literature search, the researcher has suggested an alternative model for CPD implementation that can result in teacher change. Overall there is need for collaborative effort among stakeholders in education to ensure effective delivery of CPDs and their subsequent translation into practice at classroom level.
- Full Text:
- Date Issued: 2011
Regional application of the Pitman monthly rainfall-runoff model in Southern Africa incorporating uncertainty
- Authors: Kapangaziwiri, Evison
- Date: 2011
- Subjects: Water supply -- Africa, Southern Water supply -- Measurement -- Africa, Southern Hydrology -- Mathematical models -- Africa, Southern Hydrologic models Rain and rainfall -- Mathematical models -- Africa, Southern Runoff -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6037 , http://hdl.handle.net/10962/d1006178
- Description: Climate change and a growing demand for freshwater resources due to population increases and socio-economic changes will make water a limiting factor (in terms of both quantity and quality) in development. The need for reliable quantitative estimates of water availability cannot be over-emphasised. However, there is frequently a paucity of the data required for this quantification as many basins, especially in the developing world, are inadequately equipped with monitoring networks. Existing networks are also shrinking due mainly to shortages in human and financial resources. Over the past few decades mathematical models have been used to bridge the data gap by generating datasets for use in management and policy making. In southern Africa, the Pitman monthly rainfall-runoff model has enjoyed relatively popular use as a water resources estimation tool. However, it is acknowledged that models are abstractions of reality and the data used to drive them is imperfect, making the model outputs uncertain. While there is acknowledgement of the limitations of modelled data in the southern African region among water practitioners, there has been little effort to explicitly quantify and account for this uncertainty in water resources estimation tools and explore how it affects the decision making process. Uncertainty manifests itself in three major areas of the modelling chain; the input data used to force the model, the parameter estimation process and the model structural errors. A previous study concluded that the parameter estimation process for the Pitman model contributed more to the global uncertainty of the model than other sources. While the literature abounds with uncertainty estimation techniques, many of these are dependent on observations and are therefore unlikely to be easily applicable to the southern African region where there is an acute shortage of such data. This study focuses on two aspects of making hydrologic predictions in ungauged basins. Firstly, the study advocates the development of an a priori parameter estimation process for the Pitman model and secondly, uses indices of hydrological functional behaviour to condition and reduce predictive uncertainty in both gauged and ungauged basins. In this approach all the basins are treated as ungauged, while the historical records in the gauged basins are used to develop regional indices of expected hydrological behaviour and assess the applicability of these methods. Incorporating uncertainty into the hydrologic estimation tools used in southern Africa entails rethinking the way the uncertain results can be used in further analysis and how they will be interpreted by stakeholders. An uncertainty framework is proposed. The framework is made up of a number of components related to the estimation of the prior distribution of the parameters, used to generate output ensembles which are then assessed and constrained using regionalised indices of basin behavioural responses. This is premised on such indices being based on the best available knowledge covering different regions. This framework is flexible enough to be used with any model structure to ensure consistent and comparable results. While the aim is to eventually apply the uncertainty framework in the southern African region, this study reports on the preliminary work on the development and testing of the framework components based on South African basins. This is necessitated by the variations in the availability and quality of the data across the region. Uncertainty in the parameter estimation process was incorporated by assuming uncertainty in the physical and hydro-meteorological data used to directly quantify the parameter. This uncertainty was represented by the range of variability of these basin characteristics and probability distribution functions were developed to account for this uncertainty and propagate it through the estimation process to generate posterior distributions for the parameters. The results show that the framework has a great deal of potential but can still be improved. In general, the estimated uncertain parameters managed to produce hydrologically realistic model outputs capturing the expected regimes across the different hydro-climatic and geo-physical gradients examined. The regional relationships for the three indices developed and tested in this study were in general agreement with existing knowledge and managed to successfully provide a multi-criteria conditioning of the model output ensembles. The feedback loop included in the framework enabled a systematic re-examination of the estimation procedures for both the parameters and the indices when inconsistencies in the results were identified. This improved results. However, there is need to carefully examine the issues and problems that may arise within other basins outside South Africa and develop guidelines for the use of the framework. , iText 1.4.6 (by lowagie.com)
- Full Text:
- Date Issued: 2011
- Authors: Kapangaziwiri, Evison
- Date: 2011
- Subjects: Water supply -- Africa, Southern Water supply -- Measurement -- Africa, Southern Hydrology -- Mathematical models -- Africa, Southern Hydrologic models Rain and rainfall -- Mathematical models -- Africa, Southern Runoff -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6037 , http://hdl.handle.net/10962/d1006178
- Description: Climate change and a growing demand for freshwater resources due to population increases and socio-economic changes will make water a limiting factor (in terms of both quantity and quality) in development. The need for reliable quantitative estimates of water availability cannot be over-emphasised. However, there is frequently a paucity of the data required for this quantification as many basins, especially in the developing world, are inadequately equipped with monitoring networks. Existing networks are also shrinking due mainly to shortages in human and financial resources. Over the past few decades mathematical models have been used to bridge the data gap by generating datasets for use in management and policy making. In southern Africa, the Pitman monthly rainfall-runoff model has enjoyed relatively popular use as a water resources estimation tool. However, it is acknowledged that models are abstractions of reality and the data used to drive them is imperfect, making the model outputs uncertain. While there is acknowledgement of the limitations of modelled data in the southern African region among water practitioners, there has been little effort to explicitly quantify and account for this uncertainty in water resources estimation tools and explore how it affects the decision making process. Uncertainty manifests itself in three major areas of the modelling chain; the input data used to force the model, the parameter estimation process and the model structural errors. A previous study concluded that the parameter estimation process for the Pitman model contributed more to the global uncertainty of the model than other sources. While the literature abounds with uncertainty estimation techniques, many of these are dependent on observations and are therefore unlikely to be easily applicable to the southern African region where there is an acute shortage of such data. This study focuses on two aspects of making hydrologic predictions in ungauged basins. Firstly, the study advocates the development of an a priori parameter estimation process for the Pitman model and secondly, uses indices of hydrological functional behaviour to condition and reduce predictive uncertainty in both gauged and ungauged basins. In this approach all the basins are treated as ungauged, while the historical records in the gauged basins are used to develop regional indices of expected hydrological behaviour and assess the applicability of these methods. Incorporating uncertainty into the hydrologic estimation tools used in southern Africa entails rethinking the way the uncertain results can be used in further analysis and how they will be interpreted by stakeholders. An uncertainty framework is proposed. The framework is made up of a number of components related to the estimation of the prior distribution of the parameters, used to generate output ensembles which are then assessed and constrained using regionalised indices of basin behavioural responses. This is premised on such indices being based on the best available knowledge covering different regions. This framework is flexible enough to be used with any model structure to ensure consistent and comparable results. While the aim is to eventually apply the uncertainty framework in the southern African region, this study reports on the preliminary work on the development and testing of the framework components based on South African basins. This is necessitated by the variations in the availability and quality of the data across the region. Uncertainty in the parameter estimation process was incorporated by assuming uncertainty in the physical and hydro-meteorological data used to directly quantify the parameter. This uncertainty was represented by the range of variability of these basin characteristics and probability distribution functions were developed to account for this uncertainty and propagate it through the estimation process to generate posterior distributions for the parameters. The results show that the framework has a great deal of potential but can still be improved. In general, the estimated uncertain parameters managed to produce hydrologically realistic model outputs capturing the expected regimes across the different hydro-climatic and geo-physical gradients examined. The regional relationships for the three indices developed and tested in this study were in general agreement with existing knowledge and managed to successfully provide a multi-criteria conditioning of the model output ensembles. The feedback loop included in the framework enabled a systematic re-examination of the estimation procedures for both the parameters and the indices when inconsistencies in the results were identified. This improved results. However, there is need to carefully examine the issues and problems that may arise within other basins outside South Africa and develop guidelines for the use of the framework. , iText 1.4.6 (by lowagie.com)
- Full Text:
- Date Issued: 2011
Systematics, morphology, phylogeny and historical biogeography of the Mayfly family Prosopistomatidae (Ephemeroptera: Insecta) of the world
- Barber-James, Helen Margaret
- Authors: Barber-James, Helen Margaret
- Date: 2011
- Subjects: Mayflies Mayflies -- Classification Mayflies -- Morphology Mayflies -- Phylogeny Mayflies -- Geographical distribution Ephemeridae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5785 , http://hdl.handle.net/10962/d1005473
- Description: The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa.
- Full Text:
- Date Issued: 2011
- Authors: Barber-James, Helen Margaret
- Date: 2011
- Subjects: Mayflies Mayflies -- Classification Mayflies -- Morphology Mayflies -- Phylogeny Mayflies -- Geographical distribution Ephemeridae
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5785 , http://hdl.handle.net/10962/d1005473
- Description: The diversity, classification and historical biogeography of the mayfly family Prosopistomatidae are explored. First, the higher classification of the Ephemeroptera is reviewed, focussing on the phylogenetic placement of the Prosopistomatidae relative to other mayfly families. All relevant literature from 1762 to 2010 is synthesized. Baetiscidae are established as the probable sister lineage of Prosopistomatidae, the two constituting the superfamily Baetiscoidea. Next, qualitative morphological variation within the Prosopistomatidae is reviewed and revised, emphasizing nymphs because imaginal specimens are few. The labium and associated structures and the hypopharynx of nymphs, and the highly-derived wing venation of the imaginal stages, are re-interpreted. The structure of the male tarsal claws changes considerably between subimago and imago, which, together with deeply scalloped ridges on male imaginal forelegs and unusual pits on the female thorax, are interpreted as providing an unusual mating mechanism. These structures provide morphological characters for species definition and phylogenetic analyses. Two approaches to species delimitation are explored. First, morphometric variation is analysed using Principal Component Analysis, revealing groupings that can be interpreted as species, although there is some overlap between them. Discriminant Function Analysis shows that head width and carapace shape have the most value in identifying nymphs of different species. The carapace of Prosopistoma nymphs is shown to grow allometrically and gradually, in contrast with that of Baetisca, indicating a difference in early ontogeny. Second, an Artificial Neural Network algorithm applied to nymphal morphological characters accurately identified species. This computer-driven artificial intelligence method has power to provide future easy-to-use electronic identification aids. Phylogenetic analysis of nymphal morphology using the parsimony method shows two clades of Prosopistomatidae, one sharing characters with the type species, Prosopistoma variegatum and the other predominating in Africa, although also occurring in Asia; these clades are named the “P. variegatum” and “African” clades, respectively. Parsimony analysis of adult morphology supports these two clades, but supertree analysis obscures the relationships, nesting the “P. variegatum” lineage within the other clade. Preliminary molecular phylogenetic analysis of the 16S rRNA, (mitochondrial) 18S rRNA and Histone-3 genes using Bayesian Inference methods does not support the two clades shown by morphology. Instead, there is a strong relationship between the European species and one African species, with the single Asian representative being most distantly related. These results are limited by lack of fresh material, patchy taxon sampling, and problems with finding suitable primers. A molecular clock program, BEAST, calibrated using fossils, suggests divergence times for the oldest crown-group Prosopistoma clade, represented by the Asian P. wouterae, of about 131 Ma, with the youngest species, the African P. crassi, of 1.21 Ma. Stem-group relationships are analysed using parsimony analysis, focussing on wing characters of the Baetiscoidea, other extant mayfly lineages, and extinct stem-group lineages. This suggests that the Baetiscoidea diverged from main-line Ephemeroptera earlier than any other extant mayfly lineage. This approach expands upon ideas hinted at by earlier scientists. Finally, historical biogeographical analysis of the distribution of known Baetiscoidea s.s. stem-group fossils implies a once Pangean distribution of the lineage. Changing palaeo-climate, catastrophic extinction events and plate tectonic movements in relation to the distribution of crown-group species are reviewed. Other approaches to historical biogeography that build on both morphological and molecular phylogenies are used to interpret disperalist and vacarianist arguments. Distribution patterns of eight unrelated freshwater organisms which share a similar distribution pattern are compared, assuming that shared patterns indicate similar historic biogeographic processes. The distribution of recent Prosopistoma species is seen to be the product of evolution resulting from both vicariance and dispersal. In conclusion, this thesis encompasses a variety of disciplines. It successfully recognises new characters and distinguishes previously unknown species. It uses new approaches to delimiting species and known methods to determine phylogeny from several angles. The analysis of stem-group relationships offers an insight into possible early lineage splitting within Ephemeroptera. Interpretation of historical biogeography allows for both a Gondwanan origin of Prosopistomatidae, with rafting of species on the Deccan plate to Asia, and for subsequent dispersal from Asia down to Australia and across to Europe, and possibly back to Africa.
- Full Text:
- Date Issued: 2011
Adequacy of the advanced certificate in education to develop the work-intergrated learning competencies of principals: a case study
- Authors: Dali, Christopher Malizo
- Date: 2011
- Subjects: School principals -- Training of -- South Africa -- Eastern Cape , Emotional intelligence -- Study and teaching -- South Africa -- Eastern Cape , Educational leadership -- South Africa -- Eastern Cape , School management and organization -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9472 , http://hdl.handle.net/10948/1342 , School principals -- Training of -- South Africa -- Eastern Cape , Emotional intelligence -- Study and teaching -- South Africa -- Eastern Cape , Educational leadership -- South Africa -- Eastern Cape , School management and organization -- South Africa -- Eastern Cape
- Description: The aim of this study was to explore the adequacy of the Advanced Certificate in Education (School Leadership) programme to develop the school principals’ workintegrated learning competencies (WILCs) at the Higher Education Institutions (HEIs). One of the objectives of this study was therefore to determine the extent to which the Advanced Certificate in Education (ACE) – School Leadership (SL) programme could utilise emotional intelligence (EI) to develop the principals’ intrapersonal and interpersonal competencies for collegial leadership. Another objective was to explore the school principals’ perceptions of their emotional competencies that could link their theoretical studies at the Nelson Mandela Metropolitan University (NMMU) with their practical learning experiences in their schools. Presently, one of the major programmes that could use EI in the development of school principals’ WILCs is the ACE (SL) programme offered by HEIs. The challenge for HEIs, such as the NMMU, is to offer an ACE (SL) programme that is capable of empowering principals from divergent school backgrounds. This would enable them to better understand and interpret the contextual evironments in their schools and their emotional relationships with their teachers as colleagues. The purposively selected research participants for this study comprised of school principals from one hundred and thirty rural, urban, township and farm schools. These schools are located in areas such as Lusikisiki, Bizana, Kokstad, Maluti, Mount Frere, Mount Fletcher, Cradock, Graaff-Reinet, Uitenhage and Port Elizabeth. For the purposes of triangulation, forty-two semi-structured questionnaire responses, five focus group interviews, ten in-depth interviews, and the school principals’ portfolio reflections, were used in the collection and analysis of the data. The findings of this interpretive, explorative, descriptive, and phenomenological study revealed that generally, the school principals had satisfactory levels of EI, firstly especially in terms of their intrapersonal competencies such as adaptability, v achievement drive, commitment, initiative and optimism. The school principals valued the opportunity afforded to them by the ACE (SL) programme to discuss their individual emotions and experiences with principals from similar and different school contexts. The ACE (SL) programme helped them to interrogate and express their own perceptions and experiences and the WILCs required in their leadership positions in schools. Secondly, the findings on the effectiveness of the interpersonal WILCs revealed that most of the school principals were adept at inducing desirable feelings and actions in their teachers. The feedback from the semi-structured questionnaire, the in-depth interviews, the focus group interviews, and the principals’ reflection portfolios indicated that EI could strongly influence the development of the WILCs of school principals. Politically astute principals know how to collaborate with teachers to achieve school goals. They create a culture of trust and achievement as they collaborate as colleagues in their schools. In conceptualising the development of the WILCs of school principals, one of the major recommendations emanating from this study is the utilisation of the WILCs model to develop the school principals’ collegial leadership abilities. The WILCs model was developed as a recommendation to provide a common language for discussing emotional capabilities and guidance for a host of WILCs such as self-awareness, selfregulation, empathy, conflict management, building bonds, enabling and inspiring others to develop in a collaborative and collegial manner. Underpinning the WILCs model are five major assumptions. The first assumption is that although the intrapersonal and interpersonal competencies are essential, generic and could be applied to any organisational context, the focus in this study is on school principals and their school environments. The second assumption of this model is that the WILCs are the result of rigorous research and represent a way of describing the effective leadership abilities of principals within their school contexts. The third assumption is that the WILCs are interrelated, complex, and serve to highlight key elements of effective leadership in the school environment without privileging one over another. Fourthly, the conceptual basis for the construction of the WILCs model is the vi empowerment of principals and their interpersonal relationships with the wider school community. Fifthly, and a highly relevant assumption for school principals, this WILCs model brings together the social constructivist essence of the two epistemic sites of learning discussed in this study – the schools and the HEIs – and the interconnectedness between EI and IQ in the development of principals’ WILCs for collegial leadership. Evidently, principals cannot solely depend on their experiences only to hone their leadership competencies. Formal programmes, such as the ACE (SL) programme, are essential to develop the WILCs of school principals. Nothing less should be contemplated to develop their collegial leadership competencies.
- Full Text:
- Date Issued: 2011
- Authors: Dali, Christopher Malizo
- Date: 2011
- Subjects: School principals -- Training of -- South Africa -- Eastern Cape , Emotional intelligence -- Study and teaching -- South Africa -- Eastern Cape , Educational leadership -- South Africa -- Eastern Cape , School management and organization -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9472 , http://hdl.handle.net/10948/1342 , School principals -- Training of -- South Africa -- Eastern Cape , Emotional intelligence -- Study and teaching -- South Africa -- Eastern Cape , Educational leadership -- South Africa -- Eastern Cape , School management and organization -- South Africa -- Eastern Cape
- Description: The aim of this study was to explore the adequacy of the Advanced Certificate in Education (School Leadership) programme to develop the school principals’ workintegrated learning competencies (WILCs) at the Higher Education Institutions (HEIs). One of the objectives of this study was therefore to determine the extent to which the Advanced Certificate in Education (ACE) – School Leadership (SL) programme could utilise emotional intelligence (EI) to develop the principals’ intrapersonal and interpersonal competencies for collegial leadership. Another objective was to explore the school principals’ perceptions of their emotional competencies that could link their theoretical studies at the Nelson Mandela Metropolitan University (NMMU) with their practical learning experiences in their schools. Presently, one of the major programmes that could use EI in the development of school principals’ WILCs is the ACE (SL) programme offered by HEIs. The challenge for HEIs, such as the NMMU, is to offer an ACE (SL) programme that is capable of empowering principals from divergent school backgrounds. This would enable them to better understand and interpret the contextual evironments in their schools and their emotional relationships with their teachers as colleagues. The purposively selected research participants for this study comprised of school principals from one hundred and thirty rural, urban, township and farm schools. These schools are located in areas such as Lusikisiki, Bizana, Kokstad, Maluti, Mount Frere, Mount Fletcher, Cradock, Graaff-Reinet, Uitenhage and Port Elizabeth. For the purposes of triangulation, forty-two semi-structured questionnaire responses, five focus group interviews, ten in-depth interviews, and the school principals’ portfolio reflections, were used in the collection and analysis of the data. The findings of this interpretive, explorative, descriptive, and phenomenological study revealed that generally, the school principals had satisfactory levels of EI, firstly especially in terms of their intrapersonal competencies such as adaptability, v achievement drive, commitment, initiative and optimism. The school principals valued the opportunity afforded to them by the ACE (SL) programme to discuss their individual emotions and experiences with principals from similar and different school contexts. The ACE (SL) programme helped them to interrogate and express their own perceptions and experiences and the WILCs required in their leadership positions in schools. Secondly, the findings on the effectiveness of the interpersonal WILCs revealed that most of the school principals were adept at inducing desirable feelings and actions in their teachers. The feedback from the semi-structured questionnaire, the in-depth interviews, the focus group interviews, and the principals’ reflection portfolios indicated that EI could strongly influence the development of the WILCs of school principals. Politically astute principals know how to collaborate with teachers to achieve school goals. They create a culture of trust and achievement as they collaborate as colleagues in their schools. In conceptualising the development of the WILCs of school principals, one of the major recommendations emanating from this study is the utilisation of the WILCs model to develop the school principals’ collegial leadership abilities. The WILCs model was developed as a recommendation to provide a common language for discussing emotional capabilities and guidance for a host of WILCs such as self-awareness, selfregulation, empathy, conflict management, building bonds, enabling and inspiring others to develop in a collaborative and collegial manner. Underpinning the WILCs model are five major assumptions. The first assumption is that although the intrapersonal and interpersonal competencies are essential, generic and could be applied to any organisational context, the focus in this study is on school principals and their school environments. The second assumption of this model is that the WILCs are the result of rigorous research and represent a way of describing the effective leadership abilities of principals within their school contexts. The third assumption is that the WILCs are interrelated, complex, and serve to highlight key elements of effective leadership in the school environment without privileging one over another. Fourthly, the conceptual basis for the construction of the WILCs model is the vi empowerment of principals and their interpersonal relationships with the wider school community. Fifthly, and a highly relevant assumption for school principals, this WILCs model brings together the social constructivist essence of the two epistemic sites of learning discussed in this study – the schools and the HEIs – and the interconnectedness between EI and IQ in the development of principals’ WILCs for collegial leadership. Evidently, principals cannot solely depend on their experiences only to hone their leadership competencies. Formal programmes, such as the ACE (SL) programme, are essential to develop the WILCs of school principals. Nothing less should be contemplated to develop their collegial leadership competencies.
- Full Text:
- Date Issued: 2011
"But what story?": a narrative-discursive analysis of "white" Afrikaners' accounts of male involvement in parenthood decision-making
- Authors: Morison, Tracy
- Date: 2011
- Subjects: Family planning -- South Africa -- Psychological aspects Family size Birth intervals Men -- South Africa -- Attitudes Men -- South Africa -- Psychology Couples -- South Africa -- Psychology Afrikaners -- Attitudes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3025 , http://hdl.handle.net/10962/d1002534
- Description: Despite the increased focus on men in reproductive research, little is known about male involvement in the initial decision/s regarding parenthood (i.e., to become a parent or not) and the subsequent decision-making that may ensue (e.g., choices about timing or spacing of births). In particular, the parenthood decision-making of “White”, heterosexual men from the middle class has been understudied, as indicated in the existing literature. In South Africa, this oversight has been exacerbated by the tendency for researchers to concentrate on “problematic” men, to the exclusion of the “boring, normal case”. I argue that this silence in the literature is a result of the taken for granted nature of parenthood in the “normal” heterosexual life course. In this study, I have turned the spotlight onto the norm of “Whiteness” and heterosexuality by studying those who have previously been overlooked by researchers. I focus on “White” Afrikaans men’s involvement in parenthood decision-making. My aim was to explore how constructions of gender inform male involvement in decision-making, especially within the South African context where social transformation has challenged traditional conceptions of male selfhood giving rise to new and contested masculine identities and new discourses of manhood and fatherhood. In an effort to ensure that women’s voices are not marginalised in the research, as is often the case in studies of men and masculinity, I conducted in-depth, semi-structured interviews about male involvement in decision-making with both “White” Afrikaans women and men. There were 23 participants in total, who all identified as heterosexual and middle-class. The participants were divided into two age cohorts (21 – 30 years and >40 years), which were then differentiated according to gender, reproductive status, and relationship status. Treating the interviews as jointly produced narratives, I analysed them by means of a performativity/performance lens. This dual analytic lens focuses on how particular narrative performances are simultaneously shaped by the interview setting and the broader discursive context. The lens was fashioned by synthesising Butler’s theory of performativity with Taylor’s narrative-discursive method. This synthesis (1) allows for Butler’s notion of “performativity” to be supplemented with that of “performance”; (2) provides a concrete analytical strategy in the form of positioning analysis; and (3) draws attention to both the micro politics of the interview conversation and the operation of power on the macro level, including the possibility of making “gender trouble”. The findings of the study suggest that the participants experienced difficulty narrating about male involvement in parenthood decision-making, owing to the taken for granted nature of parenthood for heterosexual adults. This was evident in participants’ sidelining of issues of “deciding” and “planning” and their alternate construal of childbearing as a non-choice, which, significantly served to bolster hetero-patriarchal norms. A central rhetorical tool for accomplishing these purposes was found in the construction of the “sacralised” child. In discursively manoeuvring around the central problematic, the participants ultimately produced a “silence” in the data that repeats the one in the research literature.
- Full Text:
- Date Issued: 2011
- Authors: Morison, Tracy
- Date: 2011
- Subjects: Family planning -- South Africa -- Psychological aspects Family size Birth intervals Men -- South Africa -- Attitudes Men -- South Africa -- Psychology Couples -- South Africa -- Psychology Afrikaners -- Attitudes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3025 , http://hdl.handle.net/10962/d1002534
- Description: Despite the increased focus on men in reproductive research, little is known about male involvement in the initial decision/s regarding parenthood (i.e., to become a parent or not) and the subsequent decision-making that may ensue (e.g., choices about timing or spacing of births). In particular, the parenthood decision-making of “White”, heterosexual men from the middle class has been understudied, as indicated in the existing literature. In South Africa, this oversight has been exacerbated by the tendency for researchers to concentrate on “problematic” men, to the exclusion of the “boring, normal case”. I argue that this silence in the literature is a result of the taken for granted nature of parenthood in the “normal” heterosexual life course. In this study, I have turned the spotlight onto the norm of “Whiteness” and heterosexuality by studying those who have previously been overlooked by researchers. I focus on “White” Afrikaans men’s involvement in parenthood decision-making. My aim was to explore how constructions of gender inform male involvement in decision-making, especially within the South African context where social transformation has challenged traditional conceptions of male selfhood giving rise to new and contested masculine identities and new discourses of manhood and fatherhood. In an effort to ensure that women’s voices are not marginalised in the research, as is often the case in studies of men and masculinity, I conducted in-depth, semi-structured interviews about male involvement in decision-making with both “White” Afrikaans women and men. There were 23 participants in total, who all identified as heterosexual and middle-class. The participants were divided into two age cohorts (21 – 30 years and >40 years), which were then differentiated according to gender, reproductive status, and relationship status. Treating the interviews as jointly produced narratives, I analysed them by means of a performativity/performance lens. This dual analytic lens focuses on how particular narrative performances are simultaneously shaped by the interview setting and the broader discursive context. The lens was fashioned by synthesising Butler’s theory of performativity with Taylor’s narrative-discursive method. This synthesis (1) allows for Butler’s notion of “performativity” to be supplemented with that of “performance”; (2) provides a concrete analytical strategy in the form of positioning analysis; and (3) draws attention to both the micro politics of the interview conversation and the operation of power on the macro level, including the possibility of making “gender trouble”. The findings of the study suggest that the participants experienced difficulty narrating about male involvement in parenthood decision-making, owing to the taken for granted nature of parenthood for heterosexual adults. This was evident in participants’ sidelining of issues of “deciding” and “planning” and their alternate construal of childbearing as a non-choice, which, significantly served to bolster hetero-patriarchal norms. A central rhetorical tool for accomplishing these purposes was found in the construction of the “sacralised” child. In discursively manoeuvring around the central problematic, the participants ultimately produced a “silence” in the data that repeats the one in the research literature.
- Full Text:
- Date Issued: 2011
Money attitudes and materialism among generation Y South Africans: a life-course study
- Authors: Duh, Helen Inseng
- Date: 2011
- Subjects: Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: vital:9286 , http://hdl.handle.net/10948/d1008612 , Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Description: Materialism has long been a subject of interest to researchers. More negative than positive consequences have been reported from studies on the lifestyles of materialists. For example, increased consumer and credit card debt, shrinking saving rates, increased number of consumers filing for bankruptcy, lower levels of life satisfaction and the depletion of natural resources are reported to be emanating from the increasing levels of materialism in societies. It is thus important to investigate the factors that can be implicated for the growth of materialism. Most of the studies attempt to explain materialism at a given point in time in isolation of the events people have experienced in their early life or childhood. Realizing that this practice is a shortcoming in consumer research, there is a call that consumer behaviour, such as materialism, be studied as a function of past life experiences using the life-course approach. While few studies have applied this approach to understanding materialism, little is known about the psychological processes that link childhood family structure to materialism. It is against this background that this study used the life-course approach to study how childhood family structure affects materialism through psychological processes of perceived family resources (tangible and intangible), perceived stress from the disruptive family events, and money attitudes of Generation Y South Africans. The study also assessed the moderating role of money attitudes on the relationship between childhood family experiences and materialism. Money attitude dimensions of status, achievement, worry, security and budget were introduced to broaden the life-course study of materialism because they are reported to begin in childhood, to remain in adulthood and they function in the background of every behavioural intention and action. Generation Y (commonly reported to be born between 1977 and 1994) were the subject of this study, because the literature reviewed revealed that these emerging consumers are not only numerous (about 30 percent of South Africans are Generation Y), have considerable influence and spending power, but most have been raised in disrupted single-parent/income families. With reports from family sociologists on the outcomes of divorce and single-parenthood (for example, stress, inadequate family resources, and low self-esteem) questions were raised as to how these outcomes would affect Generation Y money attitudes and materialistic values. Ten hypotheses were formulated to empirically answer the research questions. Using quantitative methodologies based on the nature of the research questions and problems, data were collected through online questionnaire from 826 business undergraduate students from the Nelson Mandela Metropolitan and Western Cape Universities. University-aged respondents were appropriate for this study since they are ideally suited to remember their past family circumstances and must have already formed consumption habits, attitudes and values at their age. The first research problem was to evaluate how two of the life-course theoretical perspectives (i.e., family resources and stress) selected for this study would explain the materialistic values of Generation Y South Africans raised in non-intact (did not live with both biological parents before 18th birthday) and intact (lived with both biological parents before 18th birthday) family structures through the money attitudes adopted. The results showed that even though a significant difference in perceived family resources (both tangible and intangible) and stress was found between subjects raised in non-intact (or disrupted) and intact families, the difference in materialism as a whole was not significant. In terms of the three materialistic values of success, happiness and centrality, subjects raised in disrupted families significantly scored higher in the happiness dimension. For the money attitude dimensions of status, achievement, worry, budget and security they significantly scored higher in the worry money attitude. Results of the correlation analyses showed that perceived decrease in tangible (food, clothing and pocket money) family resources was a childhood factor that affected later worry money attitude to significantly and positively influence all of the three materialistic values. Perceived decreases in intangible family resources (for example, love and emotional support) negatively affected the symbolic money attitudes of status and worry, which in turn, positively affected only the happiness dimension of materialism. Perceived increase in stress positively affected all of the symbolic money attitudes of status, worry and achievement. These, in turn, positively influenced only the success and happiness materialistic values. The second research problem was based on an assessment of the moderating role of money attitudes on the childhood family experiences to materialism relationship. Using hierarchical regression analyses, it was found that only the achievement and worry money attitude dimensions moderated the family resources to materialism relationship. This means that when subjects hold higher worry and achievement money attitudes, an increase in family resources (tangible and intangible) will have less effect in reducing materialistic tendencies. For the stress to materialism relationship, only the worry money attitude dimension had a moderating effect, meaning that when higher worry money attitude is held, an increase in stress from family disruptions would have a greater effect in increasing materialistic tendencies. None of the five money attitude dimensions did, however, moderate the childhood family structure to materialism relationship. The results of this study do not only have theoretical implications, but also provide valuable information to consumer-interest groups, banks and retailers, especially in terms of the money attitudes of Generation Y consumers in South Africa.
- Full Text:
- Date Issued: 2011
- Authors: Duh, Helen Inseng
- Date: 2011
- Subjects: Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Language: English
- Type: Thesis , Doctoral , DCom
- Identifier: vital:9286 , http://hdl.handle.net/10948/d1008612 , Consumers -- Research , Materialism , Consumer -- Behaviour , Consumer credit
- Description: Materialism has long been a subject of interest to researchers. More negative than positive consequences have been reported from studies on the lifestyles of materialists. For example, increased consumer and credit card debt, shrinking saving rates, increased number of consumers filing for bankruptcy, lower levels of life satisfaction and the depletion of natural resources are reported to be emanating from the increasing levels of materialism in societies. It is thus important to investigate the factors that can be implicated for the growth of materialism. Most of the studies attempt to explain materialism at a given point in time in isolation of the events people have experienced in their early life or childhood. Realizing that this practice is a shortcoming in consumer research, there is a call that consumer behaviour, such as materialism, be studied as a function of past life experiences using the life-course approach. While few studies have applied this approach to understanding materialism, little is known about the psychological processes that link childhood family structure to materialism. It is against this background that this study used the life-course approach to study how childhood family structure affects materialism through psychological processes of perceived family resources (tangible and intangible), perceived stress from the disruptive family events, and money attitudes of Generation Y South Africans. The study also assessed the moderating role of money attitudes on the relationship between childhood family experiences and materialism. Money attitude dimensions of status, achievement, worry, security and budget were introduced to broaden the life-course study of materialism because they are reported to begin in childhood, to remain in adulthood and they function in the background of every behavioural intention and action. Generation Y (commonly reported to be born between 1977 and 1994) were the subject of this study, because the literature reviewed revealed that these emerging consumers are not only numerous (about 30 percent of South Africans are Generation Y), have considerable influence and spending power, but most have been raised in disrupted single-parent/income families. With reports from family sociologists on the outcomes of divorce and single-parenthood (for example, stress, inadequate family resources, and low self-esteem) questions were raised as to how these outcomes would affect Generation Y money attitudes and materialistic values. Ten hypotheses were formulated to empirically answer the research questions. Using quantitative methodologies based on the nature of the research questions and problems, data were collected through online questionnaire from 826 business undergraduate students from the Nelson Mandela Metropolitan and Western Cape Universities. University-aged respondents were appropriate for this study since they are ideally suited to remember their past family circumstances and must have already formed consumption habits, attitudes and values at their age. The first research problem was to evaluate how two of the life-course theoretical perspectives (i.e., family resources and stress) selected for this study would explain the materialistic values of Generation Y South Africans raised in non-intact (did not live with both biological parents before 18th birthday) and intact (lived with both biological parents before 18th birthday) family structures through the money attitudes adopted. The results showed that even though a significant difference in perceived family resources (both tangible and intangible) and stress was found between subjects raised in non-intact (or disrupted) and intact families, the difference in materialism as a whole was not significant. In terms of the three materialistic values of success, happiness and centrality, subjects raised in disrupted families significantly scored higher in the happiness dimension. For the money attitude dimensions of status, achievement, worry, budget and security they significantly scored higher in the worry money attitude. Results of the correlation analyses showed that perceived decrease in tangible (food, clothing and pocket money) family resources was a childhood factor that affected later worry money attitude to significantly and positively influence all of the three materialistic values. Perceived decreases in intangible family resources (for example, love and emotional support) negatively affected the symbolic money attitudes of status and worry, which in turn, positively affected only the happiness dimension of materialism. Perceived increase in stress positively affected all of the symbolic money attitudes of status, worry and achievement. These, in turn, positively influenced only the success and happiness materialistic values. The second research problem was based on an assessment of the moderating role of money attitudes on the childhood family experiences to materialism relationship. Using hierarchical regression analyses, it was found that only the achievement and worry money attitude dimensions moderated the family resources to materialism relationship. This means that when subjects hold higher worry and achievement money attitudes, an increase in family resources (tangible and intangible) will have less effect in reducing materialistic tendencies. For the stress to materialism relationship, only the worry money attitude dimension had a moderating effect, meaning that when higher worry money attitude is held, an increase in stress from family disruptions would have a greater effect in increasing materialistic tendencies. None of the five money attitude dimensions did, however, moderate the childhood family structure to materialism relationship. The results of this study do not only have theoretical implications, but also provide valuable information to consumer-interest groups, banks and retailers, especially in terms of the money attitudes of Generation Y consumers in South Africa.
- Full Text:
- Date Issued: 2011
A framework to evaluate usable security in online social networking
- Authors: Yeratziotis, Alexandros
- Date: 2011
- Subjects: Online social networks -- Security measures , Computer security , Data protection
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9807 , http://hdl.handle.net/10948/d1012933
- Description: It is commonly held in the literature that users find security and privacy difficult to comprehend. It is also acknowledged that most end-user applications and websites have built-in security and privacy features. Users are expected to interact with these in order to protect their personal information. However, security is generally a secondary goal for users. Considering the complexity associated with security in combination with the notion that it is not users’ primary task, it makes sense that users tend to ignore their security responsibilities. As a result, they make poor security-related decisions and, consequently, their personal information is at risk. Usable Security is the field that investigates these types of issue, focusing on the design of security and privacy features that are usable. In order to understand and appreciate the complexities that exist in the field of Usable Security, the research fields of Human-Computer Interaction and Information Security should be examined. Accordingly, the Information Security field is concerned with all aspects pertaining to the security and privacy of information, while the field of Human-Computer Interaction is concerned with the design, evaluation and implementation of interactive computing systems for human use. This research delivers a framework to evaluate Usable Security in online social networks. In this study, online social networks that are particular to the health domain were used as a case study and contributed to the development of a framework consisting of three components: a process, a validation tool and a Usable Security heuristic evaluation. There is no existing qualitative process that describes how one would develop and validate a heuristic evaluation. In this regard a heuristic evaluation is a usability inspection method that is used to evaluate the design of an interface for any usability violations in the field of Human-Computer Interaction. Therefore, firstly, a new process and a validation tool were required to be developed. Once this had been achieved, the process could then be followed to develop a new heuristic evaluation that is specific to Usable Security. In order to assess the validity of a new heuristic evaluation a validation tool is used. The development of tools that can improve the design of security and privacy features on end-user applications and websites in terms of their usability is critical, as this will ensure that the intended users experience them as usable and can utilise them effectively. The framework for evaluating Usable Security contributes to this objective in the context of online social networks.
- Full Text:
- Date Issued: 2011
- Authors: Yeratziotis, Alexandros
- Date: 2011
- Subjects: Online social networks -- Security measures , Computer security , Data protection
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9807 , http://hdl.handle.net/10948/d1012933
- Description: It is commonly held in the literature that users find security and privacy difficult to comprehend. It is also acknowledged that most end-user applications and websites have built-in security and privacy features. Users are expected to interact with these in order to protect their personal information. However, security is generally a secondary goal for users. Considering the complexity associated with security in combination with the notion that it is not users’ primary task, it makes sense that users tend to ignore their security responsibilities. As a result, they make poor security-related decisions and, consequently, their personal information is at risk. Usable Security is the field that investigates these types of issue, focusing on the design of security and privacy features that are usable. In order to understand and appreciate the complexities that exist in the field of Usable Security, the research fields of Human-Computer Interaction and Information Security should be examined. Accordingly, the Information Security field is concerned with all aspects pertaining to the security and privacy of information, while the field of Human-Computer Interaction is concerned with the design, evaluation and implementation of interactive computing systems for human use. This research delivers a framework to evaluate Usable Security in online social networks. In this study, online social networks that are particular to the health domain were used as a case study and contributed to the development of a framework consisting of three components: a process, a validation tool and a Usable Security heuristic evaluation. There is no existing qualitative process that describes how one would develop and validate a heuristic evaluation. In this regard a heuristic evaluation is a usability inspection method that is used to evaluate the design of an interface for any usability violations in the field of Human-Computer Interaction. Therefore, firstly, a new process and a validation tool were required to be developed. Once this had been achieved, the process could then be followed to develop a new heuristic evaluation that is specific to Usable Security. In order to assess the validity of a new heuristic evaluation a validation tool is used. The development of tools that can improve the design of security and privacy features on end-user applications and websites in terms of their usability is critical, as this will ensure that the intended users experience them as usable and can utilise them effectively. The framework for evaluating Usable Security contributes to this objective in the context of online social networks.
- Full Text:
- Date Issued: 2011
Molecular analysis of genetic diversity in dometicated pigeonpea (Cajanus cajan (L.) Millsp.) and wild relatives
- Authors: Kassa, Mulualem Tamiru
- Date: 2011
- Subjects: Pigeon pea -- Variation Cajanus -- Variation Pigeon pea -- Genetics Cajanus -- Genetics Biodiversity Pigeon pea -- Phylogeny Cajanus -- Phylogeny Plant hybridization Plant diversity Transgenic plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4204 , http://hdl.handle.net/10962/d1003773
- Description: Cajanus cajan (L.) Millsp. (Pigeonpea) belongs to the Leguminosae genus Cajanus which is composed of 34 species. Pigeonpea is the only cultivated member of the genus, while the remaining species are wild relatives belonging mainly to the secondary gene pool. DNA sequence data from the nuclear ITS region and the chloroplast trnL-F spacer were utilized to investigate the phylogenetic relationships between Cajanus and five other allied genera in the subtribe Cajaninae. This study revealed the non-monophyly of Cajanus and Rhynchosia and supported the monophyly of Eriosema and Flemingia, but more sampling ,especially from the large genera of Rhynchosia and Eriosema, is recommend to adequately test the hypothesis of generic monophyly. The phylogenetic relationships within the genus Cajanus resolved Cajanus scarabaeoides (L.) Thouars as the most basal species in the Cajanus clade. The study also utilized Single Nucleotide Polymorphism (SNP) markers derived from low copy orthologous genes and genotyped using the high throughput SNP-OPA Illumina golden gate assay. The aim was to understand phylogenetic and domestication history, genetic structure, patterns of genetic diversity, gene flow and historical hybridization between Cajanus cajan (pigeonpea) and wild relatives. The neighbor-joining tree resolved well-supported clusters, which reflect the distinctiveness of species and congruence with their geographical origin. It supported the ITS based phylogeny and resolved C. scarabaeoides as basal to the Cajanus clade. The phylogenetic signal and genetic signatures revealed insights into the domestication history of pigeonpea. Our results supported Cajanus cajanifolius as the presumed progenitor of pigeonpea and we speculate that for pigeonpea there was a single major domestication event in India. Genetic admixture and historical hybridization were evident between pigeonpea and wild relatives. Abundant allelic variation and genetic diversity was found in the wild relatives, with the exception of wild species from Australia, as compared to the domesticated pigeonpea. There was a reduction of about 75% in genetic polymorphism in domesticated pigeonpea as compared to the wild relatives, indicating a severe “domestication bottleneck” during pigeonpea domestication. We discovered SNP markers associated with disease resistance (NBS-LRR) loci. The SNPs were mined in a comparison of BAC-end sequences (BES) of C. cajan and amplicons of the wild species, C. scarabaeoides. A total of ~3000 SNPs were identified from 304 BES. These SNPs could potentially be used in constructing a genetic map and for marker assisted breeding.
- Full Text:
- Date Issued: 2011
- Authors: Kassa, Mulualem Tamiru
- Date: 2011
- Subjects: Pigeon pea -- Variation Cajanus -- Variation Pigeon pea -- Genetics Cajanus -- Genetics Biodiversity Pigeon pea -- Phylogeny Cajanus -- Phylogeny Plant hybridization Plant diversity Transgenic plants
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4204 , http://hdl.handle.net/10962/d1003773
- Description: Cajanus cajan (L.) Millsp. (Pigeonpea) belongs to the Leguminosae genus Cajanus which is composed of 34 species. Pigeonpea is the only cultivated member of the genus, while the remaining species are wild relatives belonging mainly to the secondary gene pool. DNA sequence data from the nuclear ITS region and the chloroplast trnL-F spacer were utilized to investigate the phylogenetic relationships between Cajanus and five other allied genera in the subtribe Cajaninae. This study revealed the non-monophyly of Cajanus and Rhynchosia and supported the monophyly of Eriosema and Flemingia, but more sampling ,especially from the large genera of Rhynchosia and Eriosema, is recommend to adequately test the hypothesis of generic monophyly. The phylogenetic relationships within the genus Cajanus resolved Cajanus scarabaeoides (L.) Thouars as the most basal species in the Cajanus clade. The study also utilized Single Nucleotide Polymorphism (SNP) markers derived from low copy orthologous genes and genotyped using the high throughput SNP-OPA Illumina golden gate assay. The aim was to understand phylogenetic and domestication history, genetic structure, patterns of genetic diversity, gene flow and historical hybridization between Cajanus cajan (pigeonpea) and wild relatives. The neighbor-joining tree resolved well-supported clusters, which reflect the distinctiveness of species and congruence with their geographical origin. It supported the ITS based phylogeny and resolved C. scarabaeoides as basal to the Cajanus clade. The phylogenetic signal and genetic signatures revealed insights into the domestication history of pigeonpea. Our results supported Cajanus cajanifolius as the presumed progenitor of pigeonpea and we speculate that for pigeonpea there was a single major domestication event in India. Genetic admixture and historical hybridization were evident between pigeonpea and wild relatives. Abundant allelic variation and genetic diversity was found in the wild relatives, with the exception of wild species from Australia, as compared to the domesticated pigeonpea. There was a reduction of about 75% in genetic polymorphism in domesticated pigeonpea as compared to the wild relatives, indicating a severe “domestication bottleneck” during pigeonpea domestication. We discovered SNP markers associated with disease resistance (NBS-LRR) loci. The SNPs were mined in a comparison of BAC-end sequences (BES) of C. cajan and amplicons of the wild species, C. scarabaeoides. A total of ~3000 SNPs were identified from 304 BES. These SNPs could potentially be used in constructing a genetic map and for marker assisted breeding.
- Full Text:
- Date Issued: 2011