Movement patterns, stock delineation and conservation of an overexploited fishery species, Lithognathus Lithognathus (Pisces: Sparidae)
- Authors: Bennett, Rhett Hamilton
- Date: 2012
- Subjects: Reef fishes -- Behavior , Endangered species -- South Africa , Fish stock assessment -- South Africa , Fishery management -- South Africa , Fish communities -- South Africa , Sparidae , Lithognathus , Lithognathus -- Growth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5374 , http://hdl.handle.net/10962/d1015709
- Description: White steenbras Lithognathus lithognathus (Pisces: Sparidae) has been a major target species of numerous fisheries in South Africa, since the late 19th century. Historically, it contributed substantially to annual catches in commercial net fisheries, and became dominant in recreational shore catches in the latter half of the 20th century. However, overexploitation in both sectors resulted in severe declines in abundance. The ultimate collapse of the stock by the end of the last century, and the failure of traditional management measures to protect the species indicate that a new management approach for this species is necessary. The species was identified as a priority for research, management and conservation in a National Linefish Status Report. Despite knowledge on aspects of its biology and life history, little is known about juvenile habitat use patterns, home range dynamics and movement behaviour in estuaries. Similarly, the movement and migration of larger juveniles and adults in the marine environment are poorly understood. Furthermore, there is a complete lack of information on its genetic stock structure. Such information is essential for effective management of a fishery species. This thesis aimed to address the gaps in the understanding of white steenbras movement patterns and genetic stock structure, and provide an assessment of its current conservation status. The study adopted a multidisciplinary approach, incorporating a range of methods and drawing on available information, including published literature, unpublished reports and data from long-term monitoring programmes. Acoustic telemetry, conducted in a range of estuaries, showed high site fidelity, restricted area use, small home ranges relative to the size of the estuary, and a high level of residency within estuaries at the early juvenile life stage. Behaviour within estuaries was dominated by station-keeping, superimposed by a strong diel behaviour, presumably based on feeding and/or predator avoidance, with individuals entering the shallow littoral zone at night to feed, and seeking refuge in the deeper channel areas during the daytime. Conventional dart tagging and recapture data from four ongoing, long-term coastal fish tagging projects, spread throughout the distribution of this species, indicated high levels of residency in the surf zone at the late juvenile and sub-adult life stages. Consequently, juvenile and sub-adult white steenbras are vulnerable to localised depletion, although they can be effectively protected by suitably positioned estuarine protected areas (EPAs) and marine protected areas (MPAs), respectively. It has been hypothesized that adult white steenbras undertake large-scale coastal migrations between summer aggregation areas and winter spawning grounds. The scale of observed coastal movements was correlated with fish size (and age), with larger fish undertaking considerably longer-distance coastal movements than smaller individuals, supporting this hypothesis. Given the migratory behaviour of adults, and indications that limited spawning habitat exists, MPAs designed to protect white steenbras during the adult life stage should encompass all known spawning aggregation sites. The fishery is plagued by problems such as low compliance and low enforcement capacity, and alternative management measures, such as seasonal closure, need to be evaluated. Despite considerable conventional dart tagging effort around the coastline (5 782 fish tagged) with 292 recaptures there remains a lack of empirical evidence of fish migrating long distances (> 600 km) between aggregation and spawning areas. This uncertainty in the level of connectivity among coastal regions was addressed using mitochondrial DNA sequencing and genotyping of microsatellite repeat loci in the nuclear genome, which showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the white steenbras core distribution showed high genetic diversity, low genetic differentiation and no evidence of isolation by distance or localised spawning. Although historically dominant in several fisheries, analysis of long-term commercial and recreational catch data for white steenbras indicated considerable declines and ultimately stock collapse. Improved catch-per-unit-effort in two large MPAs subsequent to closure confirmed that MPAs can be effective for the protection of white steenbras. However, the current MPA network encompasses a low proportion of sandy shoreline, for which white steenbras exhibits an affinity. Many MPAs do not prohibit recreational shore angling, which currently accounts for the greatest proportion of the total annual catch. Furthermore, EPAs within the juvenile distribution protect a negligible proportion of the total available surface area of estuaries – habitat on which white steenbras is wholly dependent. Despite some evidence of recent increases in abundance in estuaries and the surf zone in certain areas, white steenbras meets the criteria for “Endangered” on the IUCN Red List of Threatened Species, and for “Protected species” status on the National Environmental Management: Biodiversity Act of South Africa. The species requires improved management, with consideration for its life-history style, estuarine dependency, surf zone residency, predictable spawning migrations and its poor conservation status. The multidisciplinary approach provides valuable information towards an improved scientific basis for the management of white steenbras and a framework for research that can be adopted for other overexploited, estuarine-associated coastal fishery species.
- Full Text:
- Date Issued: 2012
- Authors: Bennett, Rhett Hamilton
- Date: 2012
- Subjects: Reef fishes -- Behavior , Endangered species -- South Africa , Fish stock assessment -- South Africa , Fishery management -- South Africa , Fish communities -- South Africa , Sparidae , Lithognathus , Lithognathus -- Growth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5374 , http://hdl.handle.net/10962/d1015709
- Description: White steenbras Lithognathus lithognathus (Pisces: Sparidae) has been a major target species of numerous fisheries in South Africa, since the late 19th century. Historically, it contributed substantially to annual catches in commercial net fisheries, and became dominant in recreational shore catches in the latter half of the 20th century. However, overexploitation in both sectors resulted in severe declines in abundance. The ultimate collapse of the stock by the end of the last century, and the failure of traditional management measures to protect the species indicate that a new management approach for this species is necessary. The species was identified as a priority for research, management and conservation in a National Linefish Status Report. Despite knowledge on aspects of its biology and life history, little is known about juvenile habitat use patterns, home range dynamics and movement behaviour in estuaries. Similarly, the movement and migration of larger juveniles and adults in the marine environment are poorly understood. Furthermore, there is a complete lack of information on its genetic stock structure. Such information is essential for effective management of a fishery species. This thesis aimed to address the gaps in the understanding of white steenbras movement patterns and genetic stock structure, and provide an assessment of its current conservation status. The study adopted a multidisciplinary approach, incorporating a range of methods and drawing on available information, including published literature, unpublished reports and data from long-term monitoring programmes. Acoustic telemetry, conducted in a range of estuaries, showed high site fidelity, restricted area use, small home ranges relative to the size of the estuary, and a high level of residency within estuaries at the early juvenile life stage. Behaviour within estuaries was dominated by station-keeping, superimposed by a strong diel behaviour, presumably based on feeding and/or predator avoidance, with individuals entering the shallow littoral zone at night to feed, and seeking refuge in the deeper channel areas during the daytime. Conventional dart tagging and recapture data from four ongoing, long-term coastal fish tagging projects, spread throughout the distribution of this species, indicated high levels of residency in the surf zone at the late juvenile and sub-adult life stages. Consequently, juvenile and sub-adult white steenbras are vulnerable to localised depletion, although they can be effectively protected by suitably positioned estuarine protected areas (EPAs) and marine protected areas (MPAs), respectively. It has been hypothesized that adult white steenbras undertake large-scale coastal migrations between summer aggregation areas and winter spawning grounds. The scale of observed coastal movements was correlated with fish size (and age), with larger fish undertaking considerably longer-distance coastal movements than smaller individuals, supporting this hypothesis. Given the migratory behaviour of adults, and indications that limited spawning habitat exists, MPAs designed to protect white steenbras during the adult life stage should encompass all known spawning aggregation sites. The fishery is plagued by problems such as low compliance and low enforcement capacity, and alternative management measures, such as seasonal closure, need to be evaluated. Despite considerable conventional dart tagging effort around the coastline (5 782 fish tagged) with 292 recaptures there remains a lack of empirical evidence of fish migrating long distances (> 600 km) between aggregation and spawning areas. This uncertainty in the level of connectivity among coastal regions was addressed using mitochondrial DNA sequencing and genotyping of microsatellite repeat loci in the nuclear genome, which showed no evidence of major geographic barriers to gene flow in this species. Samples collected throughout the white steenbras core distribution showed high genetic diversity, low genetic differentiation and no evidence of isolation by distance or localised spawning. Although historically dominant in several fisheries, analysis of long-term commercial and recreational catch data for white steenbras indicated considerable declines and ultimately stock collapse. Improved catch-per-unit-effort in two large MPAs subsequent to closure confirmed that MPAs can be effective for the protection of white steenbras. However, the current MPA network encompasses a low proportion of sandy shoreline, for which white steenbras exhibits an affinity. Many MPAs do not prohibit recreational shore angling, which currently accounts for the greatest proportion of the total annual catch. Furthermore, EPAs within the juvenile distribution protect a negligible proportion of the total available surface area of estuaries – habitat on which white steenbras is wholly dependent. Despite some evidence of recent increases in abundance in estuaries and the surf zone in certain areas, white steenbras meets the criteria for “Endangered” on the IUCN Red List of Threatened Species, and for “Protected species” status on the National Environmental Management: Biodiversity Act of South Africa. The species requires improved management, with consideration for its life-history style, estuarine dependency, surf zone residency, predictable spawning migrations and its poor conservation status. The multidisciplinary approach provides valuable information towards an improved scientific basis for the management of white steenbras and a framework for research that can be adopted for other overexploited, estuarine-associated coastal fishery species.
- Full Text:
- Date Issued: 2012
Assessing linkages between local ecological knowledge, HIV/AIDS and the commercialisation of natural resources across Southern Africa
- Authors: Weyer, Dylan James
- Date: 2012
- Subjects: AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4769 , http://hdl.handle.net/10962/d1007180 , AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Description: That natural resources (NRs) are important to those experiencing adversity, and, especially, vulnerability associated with HIV/AIDS, is well documented, particularly with respect to food and energy security. What is unclear is where HIV/AIDS ranks in terms of its significance in comparison to other household shocks, the role local ecological knowledge may (LEK) play in households' response to shock, a propos the types of coping strategies that are employed. Consequently, this research aims to bridge the knowledge gap between HIV/AIDS and the degree to which it is contributing to the expansion of NR commercialisation and to explore the unknowns surrounding the influence of LEK on people's choice of coping strategy. A two phase study was designed to provide quantitative rigour with qualitative depth. Phase one was an extensive, rapid survey of NR traders within urban and rural settings in five southern Africa countries. The principle objective was to profile the trade, the livelihoods of those involved and their reasons for entering the trade, to ultimately establish to what degree HIV/AIDS may have been a catalyst for this. Almost one third of the sample entered the trade in response to illness and/or death in their households, with 80% of deaths being of breadwinners. The findings illustrated considerable dependence on the sale of NRs; for almost 60% of the sample it was their household's only source of income. There was evidently increased blurring of the lines between rural and urban NR use with a greater diversity of products being traded in urban areas. Phase two involved in-depth interviews and work with a smaller sample at two sites selected based on the findings from the first phase. It incorporated three groups of households; non-trading, inexperienced trading and experienced trading households. Key areas of focus were household shocks, coping strategies employed in response to these and the role LEK may be playing in the choice of coping strategies. Within a two year period, 95% of households registered at least one shock, of which 80% recorded AIDS-related proxy shocks. Non-trading households were significantly worse-off in this regard, while in the case of non-AIDS proxy shocks, there was no such difference between groups. The most frequently employed coping strategy was the consumption and sale of NRs and was of particular importance when households were faced with AIDS proxy shocks. Trading households emerged as having superior levels of LEK in comparison to non-trading households, even for non-traded NRs, suggesting that prior LEK of NRs opened up opportunities to trade in NR as a coping strategy. Further inspection of the latter group however revealed that the portion of non-trading households who traded on a very ad hoc basis actually had comparable levels of LEK to the trading households. Despite the ad hoc trading households' vulnerable state and their disproportionately high level of AIDS proxy measures, they had at their disposal, sufficient LEK to unlock certain key coping strategies, namely the NR trade. In this sense there are apparent linkages between LEK, HIV/AIDS and the expansion of the commercialisation of NRs.
- Full Text:
- Date Issued: 2012
- Authors: Weyer, Dylan James
- Date: 2012
- Subjects: AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4769 , http://hdl.handle.net/10962/d1007180 , AIDS (Disease) -- Africa, Southern , HIV infections -- Africa, Southern , Natural resources -- Management -- Africa, Southern , Traditional ecological knowledge -- Africa, Southern , Households -- Economic aspects -- Africa, Southern , Poverty -- Environmental aspects -- Africa, Southern , Ecology -- Economic aspects -- Africa, Southern
- Description: That natural resources (NRs) are important to those experiencing adversity, and, especially, vulnerability associated with HIV/AIDS, is well documented, particularly with respect to food and energy security. What is unclear is where HIV/AIDS ranks in terms of its significance in comparison to other household shocks, the role local ecological knowledge may (LEK) play in households' response to shock, a propos the types of coping strategies that are employed. Consequently, this research aims to bridge the knowledge gap between HIV/AIDS and the degree to which it is contributing to the expansion of NR commercialisation and to explore the unknowns surrounding the influence of LEK on people's choice of coping strategy. A two phase study was designed to provide quantitative rigour with qualitative depth. Phase one was an extensive, rapid survey of NR traders within urban and rural settings in five southern Africa countries. The principle objective was to profile the trade, the livelihoods of those involved and their reasons for entering the trade, to ultimately establish to what degree HIV/AIDS may have been a catalyst for this. Almost one third of the sample entered the trade in response to illness and/or death in their households, with 80% of deaths being of breadwinners. The findings illustrated considerable dependence on the sale of NRs; for almost 60% of the sample it was their household's only source of income. There was evidently increased blurring of the lines between rural and urban NR use with a greater diversity of products being traded in urban areas. Phase two involved in-depth interviews and work with a smaller sample at two sites selected based on the findings from the first phase. It incorporated three groups of households; non-trading, inexperienced trading and experienced trading households. Key areas of focus were household shocks, coping strategies employed in response to these and the role LEK may be playing in the choice of coping strategies. Within a two year period, 95% of households registered at least one shock, of which 80% recorded AIDS-related proxy shocks. Non-trading households were significantly worse-off in this regard, while in the case of non-AIDS proxy shocks, there was no such difference between groups. The most frequently employed coping strategy was the consumption and sale of NRs and was of particular importance when households were faced with AIDS proxy shocks. Trading households emerged as having superior levels of LEK in comparison to non-trading households, even for non-traded NRs, suggesting that prior LEK of NRs opened up opportunities to trade in NR as a coping strategy. Further inspection of the latter group however revealed that the portion of non-trading households who traded on a very ad hoc basis actually had comparable levels of LEK to the trading households. Despite the ad hoc trading households' vulnerable state and their disproportionately high level of AIDS proxy measures, they had at their disposal, sufficient LEK to unlock certain key coping strategies, namely the NR trade. In this sense there are apparent linkages between LEK, HIV/AIDS and the expansion of the commercialisation of NRs.
- Full Text:
- Date Issued: 2012
An investigation of how enquiry-based fieldwork develops action competence in Grade 12 Geography: a Namibian case study
- Authors: Simasiku, Frederick
- Date: 2012
- Subjects: Competency-based education -- Namibia -- Hardap Geography -- Study and teaching (Secondary) -- Namibia -- Hardap Student-centered learning -- Namibia -- Hardap Active learning -- Namibia -- Hardap Environmental education -- Namibia -- Hardap Environmental education -- Activity programs -- Namibia -- Hardap
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1629 , http://hdl.handle.net/10962/d1003511
- Description: The goal of the study was twofold: firstly to investigate and describe how senior secondary school geography teachers were implementing enquiry-based learning through fieldwork. Secondly, to investigate and document how enquiry-based learning through fieldwork facilitated the development of action competence amongst learners in a geography classroom. In order to address the first goal, a survey questionnaire was utilised to generate descriptive data from a sample of seven geography teachers in the Hardap region of Namibia. Although teachers engaged learners with enquiry-based fieldwork learning activities it is suggested, based on the findings of data of this goal, that teachers face severe limitations in terms of integrating environmental learning into the geography curriculum. The main limitations of the teachers include: limited practical knowledge of and training in how to teach fieldwork skills; a lack of teaching resource materials; time constraints; heavy personal loads; and lack of school support for environmental education. In addressing the second goal an enquiry-based fieldwork learning unit was planned and implemented in the researcher’s classroom. Observation, focus group interviews, and audio records of learning interactions, were used as data generation methods for this cycle of the study. An indicator framework for identifying action competence in learners was constructed as a data analysis tool. In terms of the findings of goal two it is evident that enquiry-based learning through fieldwork facilitated the development of action competence amongst learners. Six overarching benefits of this type of learning were identified in this study, namely: - It empowered learners to develop contextual knowledge and understanding of issues that they investigated. - It facilitated commitment thus motivated learners to take indirect action. - It promoted social interaction and group cohesion amongst learners thus enhanced their decision-making ability for problem-solving and action taking. - It elicited emotional responses and a greater understanding of learners’ own and others’ attitudes and values towards issues. - It fostered critical thinking thus permitted learners to envisage a future based on their learning experiences. - It enabled learners to plan and take indirect action during the learning process. Based on the research findings, some lessons learned are presented in an attempt to contribute to the effective implementation of enquiry-based fieldwork at the classroom level.
- Full Text:
- Date Issued: 2012
- Authors: Simasiku, Frederick
- Date: 2012
- Subjects: Competency-based education -- Namibia -- Hardap Geography -- Study and teaching (Secondary) -- Namibia -- Hardap Student-centered learning -- Namibia -- Hardap Active learning -- Namibia -- Hardap Environmental education -- Namibia -- Hardap Environmental education -- Activity programs -- Namibia -- Hardap
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1629 , http://hdl.handle.net/10962/d1003511
- Description: The goal of the study was twofold: firstly to investigate and describe how senior secondary school geography teachers were implementing enquiry-based learning through fieldwork. Secondly, to investigate and document how enquiry-based learning through fieldwork facilitated the development of action competence amongst learners in a geography classroom. In order to address the first goal, a survey questionnaire was utilised to generate descriptive data from a sample of seven geography teachers in the Hardap region of Namibia. Although teachers engaged learners with enquiry-based fieldwork learning activities it is suggested, based on the findings of data of this goal, that teachers face severe limitations in terms of integrating environmental learning into the geography curriculum. The main limitations of the teachers include: limited practical knowledge of and training in how to teach fieldwork skills; a lack of teaching resource materials; time constraints; heavy personal loads; and lack of school support for environmental education. In addressing the second goal an enquiry-based fieldwork learning unit was planned and implemented in the researcher’s classroom. Observation, focus group interviews, and audio records of learning interactions, were used as data generation methods for this cycle of the study. An indicator framework for identifying action competence in learners was constructed as a data analysis tool. In terms of the findings of goal two it is evident that enquiry-based learning through fieldwork facilitated the development of action competence amongst learners. Six overarching benefits of this type of learning were identified in this study, namely: - It empowered learners to develop contextual knowledge and understanding of issues that they investigated. - It facilitated commitment thus motivated learners to take indirect action. - It promoted social interaction and group cohesion amongst learners thus enhanced their decision-making ability for problem-solving and action taking. - It elicited emotional responses and a greater understanding of learners’ own and others’ attitudes and values towards issues. - It fostered critical thinking thus permitted learners to envisage a future based on their learning experiences. - It enabled learners to plan and take indirect action during the learning process. Based on the research findings, some lessons learned are presented in an attempt to contribute to the effective implementation of enquiry-based fieldwork at the classroom level.
- Full Text:
- Date Issued: 2012
Synthetic and bioactivity studies of antiplasmodial and antibacterial marine natural products
- Authors: Young, Ryan Mark
- Date: 2012
- Subjects: Antibacterial agents Marine natural products Marine pharmacology Plasmodium falciparum Staphylococcus aureus Isocyanides Imidazoles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4378 , http://hdl.handle.net/10962/d1005043
- Description: This thesis is divided into two parts, assessing marine and synthetic compounds active firstly against Plasmodium falciparum (Chapter 3 and 4) and secondly active against methicillin resistant Staphylococcus aureus (MRSA, Chapter 5). In Chapter 3 the synthesis of nine new tricyclic podocarpanes (3.203-3.207 and 3.209-3.212) from the diterpene (+)-manool is described. Initial SAR study of synthetic podocarpanes concluded that the most active compound was a C-13 phenyl substituted podocarpane (3.204, IC₅₀ 6.6 μM). By preparing analogues with varying halogenated substituents on the phenyl ring (3.209-3.212) the antiplasmodial activity was improved (IC₅₀ 1.4 μM), while simultaneously decreasing the haemolysis previously reported for this class of compounds. Inspired by the antiplasmodial activity of Wright and Wattanapiromsakul’s tricycle marine isonitriles (2.16-2.21 and 2.24-2.27) an unsuccessfully attempt was made to convert tertiary alcohol moieties to isonitrile functionalities in compounds 3.188, 3.204-3.207 and 3.209-3.212. Over a decade ago Wright et al. proposed a putative antiplasmodial mechanism of action for marine isonitriles (2.4, 2.9, 2.15, 2.19 and 2.35) and isothiocyanate (2.34) which involved interference in haem detoxification by P. falciparum thus inhibiting the growth of the parasite. In Chapter 4 we describe how we successfully managed to scale down Egan’s β-haematin inhibition assay for the analyses of small quantities of marine natural products as potential β-haematin inhibitors. Our modified assay revealed that the most active antiplasmodial marine isonitrile 2.9 (IC₅₀ 13 nM) showed total β-haematin inhibition while 2.15 (IC₅₀ 81 nM) and 2.19 (IC₅₀ 31 nM) showed partial inhibition at three equivalents relative to haem. Using contempary molecular modelling techniques the charge on the isonitrile functionality was more accurately describe and the modified charge data sets was used to explore docking of marine isonitriles to haem using AutoDock. In Chapter 5 we describe how a lead South African marine bisindole MRSA pyruvate kinase inhibitor (5.8) was discovered in collaboration with colleagues at the University of British Columbia (UBC) and how this discovery inspired us to design a synthetic route to the dibrominated bisindole, isobromotopsentin (5.20) in an attempt to increase the bioactivity displayed by 5.8. We devised a fast and high yielding synthetic route using microwave assited organic synthesis. We first tested this synthesis using simple aryl glyoxals (5.27-5.32) as precursors to synthesize biphenylimidazoles (5.21-5.26), which later allowed us to synthesize the ascidian natural product 5.111. This method was sucessfully extended to the synthesis of deoxytopsentin (5.33) from an N-Boc protected indole methyl ketone (5.89). We subsequently were able to effectively remove the carbamate protection via thermal decomposition by heating the protected bisindole imidazole (5.90) in a microwave reactor for 5 min under argon. The synthesis of 5.20 resulted in an inseparable mixture of monoprotected and totally deprotected topsentin products, and due to time constraints we were not able to optimise this synthesis. Nonetheless our synthesis of the marine natural product 5.33 which was faster and higher yielding than previously reported routes could be extended to the synthesis of other topsentin bisindoles (5.138-5.140). Work towards this goal continues in our laboratory.
- Full Text:
- Date Issued: 2012
- Authors: Young, Ryan Mark
- Date: 2012
- Subjects: Antibacterial agents Marine natural products Marine pharmacology Plasmodium falciparum Staphylococcus aureus Isocyanides Imidazoles
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4378 , http://hdl.handle.net/10962/d1005043
- Description: This thesis is divided into two parts, assessing marine and synthetic compounds active firstly against Plasmodium falciparum (Chapter 3 and 4) and secondly active against methicillin resistant Staphylococcus aureus (MRSA, Chapter 5). In Chapter 3 the synthesis of nine new tricyclic podocarpanes (3.203-3.207 and 3.209-3.212) from the diterpene (+)-manool is described. Initial SAR study of synthetic podocarpanes concluded that the most active compound was a C-13 phenyl substituted podocarpane (3.204, IC₅₀ 6.6 μM). By preparing analogues with varying halogenated substituents on the phenyl ring (3.209-3.212) the antiplasmodial activity was improved (IC₅₀ 1.4 μM), while simultaneously decreasing the haemolysis previously reported for this class of compounds. Inspired by the antiplasmodial activity of Wright and Wattanapiromsakul’s tricycle marine isonitriles (2.16-2.21 and 2.24-2.27) an unsuccessfully attempt was made to convert tertiary alcohol moieties to isonitrile functionalities in compounds 3.188, 3.204-3.207 and 3.209-3.212. Over a decade ago Wright et al. proposed a putative antiplasmodial mechanism of action for marine isonitriles (2.4, 2.9, 2.15, 2.19 and 2.35) and isothiocyanate (2.34) which involved interference in haem detoxification by P. falciparum thus inhibiting the growth of the parasite. In Chapter 4 we describe how we successfully managed to scale down Egan’s β-haematin inhibition assay for the analyses of small quantities of marine natural products as potential β-haematin inhibitors. Our modified assay revealed that the most active antiplasmodial marine isonitrile 2.9 (IC₅₀ 13 nM) showed total β-haematin inhibition while 2.15 (IC₅₀ 81 nM) and 2.19 (IC₅₀ 31 nM) showed partial inhibition at three equivalents relative to haem. Using contempary molecular modelling techniques the charge on the isonitrile functionality was more accurately describe and the modified charge data sets was used to explore docking of marine isonitriles to haem using AutoDock. In Chapter 5 we describe how a lead South African marine bisindole MRSA pyruvate kinase inhibitor (5.8) was discovered in collaboration with colleagues at the University of British Columbia (UBC) and how this discovery inspired us to design a synthetic route to the dibrominated bisindole, isobromotopsentin (5.20) in an attempt to increase the bioactivity displayed by 5.8. We devised a fast and high yielding synthetic route using microwave assited organic synthesis. We first tested this synthesis using simple aryl glyoxals (5.27-5.32) as precursors to synthesize biphenylimidazoles (5.21-5.26), which later allowed us to synthesize the ascidian natural product 5.111. This method was sucessfully extended to the synthesis of deoxytopsentin (5.33) from an N-Boc protected indole methyl ketone (5.89). We subsequently were able to effectively remove the carbamate protection via thermal decomposition by heating the protected bisindole imidazole (5.90) in a microwave reactor for 5 min under argon. The synthesis of 5.20 resulted in an inseparable mixture of monoprotected and totally deprotected topsentin products, and due to time constraints we were not able to optimise this synthesis. Nonetheless our synthesis of the marine natural product 5.33 which was faster and higher yielding than previously reported routes could be extended to the synthesis of other topsentin bisindoles (5.138-5.140). Work towards this goal continues in our laboratory.
- Full Text:
- Date Issued: 2012
An investigation of the role of physical manipulatives in the teaching and learning of measurement in Grade 8 : a case study using surface area and volume
- Authors: Chiphambo, Shakespear M E K
- Date: 2012
- Subjects: Measurement -- Study and teaching -- Research Mathematics -- Education (Secondary) -- Study and teaching Teaching -- Aids and devices -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1657 , http://hdl.handle.net/10962/d1003540
- Description: The purpose of this study is to investigate the role of physical manipulatives in the teaching and learning of measurement in Grade 8. The study focuses on how the use of physical manipulatives promotes learners' mathematical proficiency in relation to the five strands of Kilpatrick, Swafford and Findell (2001). The basis of the research is a case study in the interpretive paradigm involving 18 out of a cohort of 270 Grade 8 learners in the school where I teach. The data was collected using a range of methods including: (i) baseline assessment tasks, first piloted using 7 Grade 8 learners and then given to the target group; (ii) an intervention programme with intervention tasks; (iii) a post-intervention task; (iv) observations during the intervention; and (v) individual interviews. The results of the baseline assessment and the post-intervention tasks were analysed both quantitatively and qualitatively. My research findings indicate an overall improvement of the performance after learners engaged in using physical manipulatives. The average mark of the learners in the baseline assessment task was 23% and after the intervention programme the average mark was 31 %. The responses from the learners interviewed showed that they were motivated and that the use of physical manipulatives assisted them in understanding the concepts of measurement, in particular surface area and volume. The results of my study thus reveal that the use of physical manipulatives in teaching and learning mathematics has a positive role to play in learners' understanding of surface area and volume at the Grade 8 level. The fmdings of this case study support other research regarding the importance of using physical manipulatives in teaching and learning mathematics. They align with other findings that assert that manipulatives are essential mediating tools in the development of the conceptual and procedural understanding of mathematical concepts, clarifying and helping learners to visualize abstract mathematical concepts.
- Full Text:
- Date Issued: 2012
- Authors: Chiphambo, Shakespear M E K
- Date: 2012
- Subjects: Measurement -- Study and teaching -- Research Mathematics -- Education (Secondary) -- Study and teaching Teaching -- Aids and devices -- Research
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1657 , http://hdl.handle.net/10962/d1003540
- Description: The purpose of this study is to investigate the role of physical manipulatives in the teaching and learning of measurement in Grade 8. The study focuses on how the use of physical manipulatives promotes learners' mathematical proficiency in relation to the five strands of Kilpatrick, Swafford and Findell (2001). The basis of the research is a case study in the interpretive paradigm involving 18 out of a cohort of 270 Grade 8 learners in the school where I teach. The data was collected using a range of methods including: (i) baseline assessment tasks, first piloted using 7 Grade 8 learners and then given to the target group; (ii) an intervention programme with intervention tasks; (iii) a post-intervention task; (iv) observations during the intervention; and (v) individual interviews. The results of the baseline assessment and the post-intervention tasks were analysed both quantitatively and qualitatively. My research findings indicate an overall improvement of the performance after learners engaged in using physical manipulatives. The average mark of the learners in the baseline assessment task was 23% and after the intervention programme the average mark was 31 %. The responses from the learners interviewed showed that they were motivated and that the use of physical manipulatives assisted them in understanding the concepts of measurement, in particular surface area and volume. The results of my study thus reveal that the use of physical manipulatives in teaching and learning mathematics has a positive role to play in learners' understanding of surface area and volume at the Grade 8 level. The fmdings of this case study support other research regarding the importance of using physical manipulatives in teaching and learning mathematics. They align with other findings that assert that manipulatives are essential mediating tools in the development of the conceptual and procedural understanding of mathematical concepts, clarifying and helping learners to visualize abstract mathematical concepts.
- Full Text:
- Date Issued: 2012
Identifying expansive learning opportunities to foster a more sustainable food economy: a case study of Rhodes University dining halls
- Authors: Agbedahin, Adesuwa Vanessa
- Date: 2012
- Subjects: Food supply -- Education (Higher) -- South Africa -- Case studies Food industry and trade -- Education (Higher) -- Standards -- South Africa -- Case studies Food service employees -- Education (Higher) -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1560 , http://hdl.handle.net/10962/d1003442
- Description: This is a one year half thesis. This research was conducted within the context of the food services sector of Higher Education Institution dining halls and in the midst of the rising global call for food resource management and food waste reduction. The main aim of this research therefore was to identify opportunities for learning and change for a more sustainable food economy, contributing to Education for Sustainable Production and Consumption, and by further implication, Education for Sustainable Development. To achieve this aim, I used Cultural Historical Activity Theory as theoretical and methodological framework; drawing on the second and the third generations of this theory. Implicated in the above research approach is the identification of expansive learning opportunities from the surfacing of ‘tensions’ and ‘contradictions’. In this case study of the Rhodes University Campus Food Services, such tensions and contradictions inhibiting a more sustainable food economy, involving food waste production were identified. To narrow the scope of the study, one dining hall formed the focus of the case, with a two phased research approach whereby one research question and three goals were developed for each phase. The former being the exploration phase and the latter being the initial stages of the expansive phase. Methods used in line with the methodological framework included ten individual interviews with food producers (staff members), nine focus group discussions with food consumers (students), observations of the dining hall activities which lasted for over a month and two ‘Change Laboratory Workshops’. Some of the findings of this research are that food wastage cannot be addressed and appropriately curtailed without an intensive consideration of all the stages of food economy. Multiple contradictions and sources of tensions embedded in the Food Services Sector constituted major causes of food waste. Additionally, the lack of substantial food waste related teaching and learning activities, the presence of disputed rules, institutional structure and traditional practices within the Food Services all exacerbated the tensions and contradictions. More so, prioritizing some of this identified contradictions and tensions hindering a more sustainable food economy and relegating some as unimportant or nonurgent is unproductive. Finally, the non-existence of facilitated deliberation, consultation, dialogue, collaboration between food producers and food consumers has been identified as an obstacle to learning and institutional change. Recommendations abound in re-orienting, re-educating, and re-informing the constituents of the food economy. Re-visiting and revising of rules and regulations guiding conduct of students and kitchen staff members in the RU dining halls, as well as revision of existing learning support materials and mediating tools in use is needed. Recognition and consideration of the concerns and interests of students and kitchen staff members are also needed. Finally, there is a need to continue to address the tensions and contradictions identified in this case study, to further the Expansive Learning Process if a more sustainable food economy at Rhodes University is to be established.
- Full Text:
- Date Issued: 2012
- Authors: Agbedahin, Adesuwa Vanessa
- Date: 2012
- Subjects: Food supply -- Education (Higher) -- South Africa -- Case studies Food industry and trade -- Education (Higher) -- Standards -- South Africa -- Case studies Food service employees -- Education (Higher) -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1560 , http://hdl.handle.net/10962/d1003442
- Description: This is a one year half thesis. This research was conducted within the context of the food services sector of Higher Education Institution dining halls and in the midst of the rising global call for food resource management and food waste reduction. The main aim of this research therefore was to identify opportunities for learning and change for a more sustainable food economy, contributing to Education for Sustainable Production and Consumption, and by further implication, Education for Sustainable Development. To achieve this aim, I used Cultural Historical Activity Theory as theoretical and methodological framework; drawing on the second and the third generations of this theory. Implicated in the above research approach is the identification of expansive learning opportunities from the surfacing of ‘tensions’ and ‘contradictions’. In this case study of the Rhodes University Campus Food Services, such tensions and contradictions inhibiting a more sustainable food economy, involving food waste production were identified. To narrow the scope of the study, one dining hall formed the focus of the case, with a two phased research approach whereby one research question and three goals were developed for each phase. The former being the exploration phase and the latter being the initial stages of the expansive phase. Methods used in line with the methodological framework included ten individual interviews with food producers (staff members), nine focus group discussions with food consumers (students), observations of the dining hall activities which lasted for over a month and two ‘Change Laboratory Workshops’. Some of the findings of this research are that food wastage cannot be addressed and appropriately curtailed without an intensive consideration of all the stages of food economy. Multiple contradictions and sources of tensions embedded in the Food Services Sector constituted major causes of food waste. Additionally, the lack of substantial food waste related teaching and learning activities, the presence of disputed rules, institutional structure and traditional practices within the Food Services all exacerbated the tensions and contradictions. More so, prioritizing some of this identified contradictions and tensions hindering a more sustainable food economy and relegating some as unimportant or nonurgent is unproductive. Finally, the non-existence of facilitated deliberation, consultation, dialogue, collaboration between food producers and food consumers has been identified as an obstacle to learning and institutional change. Recommendations abound in re-orienting, re-educating, and re-informing the constituents of the food economy. Re-visiting and revising of rules and regulations guiding conduct of students and kitchen staff members in the RU dining halls, as well as revision of existing learning support materials and mediating tools in use is needed. Recognition and consideration of the concerns and interests of students and kitchen staff members are also needed. Finally, there is a need to continue to address the tensions and contradictions identified in this case study, to further the Expansive Learning Process if a more sustainable food economy at Rhodes University is to be established.
- Full Text:
- Date Issued: 2012
Electrospun nanofibers : an alternative sorbent material for solid phase extraction
- Chigome, Samuel, Samuel Chigome
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
- Authors: Chigome, Samuel , Samuel Chigome
- Date: 2012 , 2012-03-26
- Subjects: Nanofibers -- Research Electrospinning -- Research Sorbents -- Research Extraction (Chemistry) -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4314 , http://hdl.handle.net/10962/d1004972
- Description: The work described in the thesis seeks to lay a foundation for a better understanding of the use of electrospun nanofibers as a sorbent material. Three miniaturised electrospun nanofiber based solid phase extraction devices were fabricated. For the first two, 10 mg of electrospun polystyrene fibers were used as a sorbent bed for a micro column SPE device (8 mm bed height in a 200 μl pipette tip) and a disk (I) SPE device (5 mm 1 mm sorbent bed in a 1000 μl SPE barrel). While for the third, 4.6 mg of electrospun nylon nanofibers were used as a sorbent bed for a disk (II) SPE device, (sorbent bed consisting of 5 5 mm 350 μm stacked disks in a 500 μl SPE barrel). Corticosteroids were employed as model analytes for performance evaluation of the fabricated SPE devices. Quantitative recoveries (45.5-124.29 percent) were achieved for all SPE devices at a loading volume of 100 μl and analyte concentration of 500 ng ml-1. Three mathematical models; the Boltzmann, Weibull five parameter and the Sigmoid three parameter were employed to describe the break through profiles of each of the sorbent beds. The micro column SPE device exhibited a breakthrough volume of 1400 μl, and theoretical plates (7.98-9.1) while disk (I) SPE device exhibited 400-500 μl and 1.39-2.82 respectively. Disk (II) SPE device exhibited a breakthrough volume of 200 μl and theoretical plates 0.38-1.15. It was proposed that the formats of future electrospun nanofiber sorbent based SPE devices will be guided by mechanical strength of the polymer. The study classified electrospun polymer fibers into two as polystyrene type (relatively low mechanical strength) and nylon type (relatively high mechanical strength).
- Full Text:
- Date Issued: 2012
Investigating tools and techniques for improving software performance on multiprocessor computer systems
- Authors: Tristram, Waide Barrington
- Date: 2012
- Subjects: Multiprocessors , Multiprogramming (Electronic computers) , Parallel programming (Computer science) , Linux , Abstract data types (Computer science) , Threads (Computer programs) , Computer programming
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4655 , http://hdl.handle.net/10962/d1006651 , Multiprocessors , Multiprogramming (Electronic computers) , Parallel programming (Computer science) , Linux , Abstract data types (Computer science) , Threads (Computer programs) , Computer programming
- Description: The availability of modern commodity multicore processors and multiprocessor computer systems has resulted in the widespread adoption of parallel computers in a variety of environments, ranging from the home to workstation and server environments in particular. Unfortunately, parallel programming is harder and requires more expertise than the traditional sequential programming model. The variety of tools and parallel programming models available to the programmer further complicates the issue. The primary goal of this research was to identify and describe a selection of parallel programming tools and techniques to aid novice parallel programmers in the process of developing efficient parallel C/C++ programs for the Linux platform. This was achieved by highlighting and describing the key concepts and hardware factors that affect parallel programming, providing a brief survey of commonly available software development tools and parallel programming models and libraries, and presenting structured approaches to software performance tuning and parallel programming. Finally, the performance of several parallel programming models and libraries was investigated, along with the programming effort required to implement solutions using the respective models. A quantitative research methodology was applied to the investigation of the performance and programming effort associated with the selected parallel programming models and libraries, which included automatic parallelisation by the compiler, Boost Threads, Cilk Plus, OpenMP, POSIX threads (Pthreads), and Threading Building Blocks (TBB). Additionally, the performance of the GNU C/C++ and Intel C/C++ compilers was examined. The results revealed that the choice of parallel programming model or library is dependent on the type of problem being solved and that there is no overall best choice for all classes of problem. However, the results also indicate that parallel programming models with higher levels of abstraction require less programming effort and provide similar performance compared to explicit threading models. The principle conclusion was that the problem analysis and parallel design are an important factor in the selection of the parallel programming model and tools, but that models with higher levels of abstractions, such as OpenMP and Threading Building Blocks, are favoured.
- Full Text:
- Date Issued: 2012
- Authors: Tristram, Waide Barrington
- Date: 2012
- Subjects: Multiprocessors , Multiprogramming (Electronic computers) , Parallel programming (Computer science) , Linux , Abstract data types (Computer science) , Threads (Computer programs) , Computer programming
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4655 , http://hdl.handle.net/10962/d1006651 , Multiprocessors , Multiprogramming (Electronic computers) , Parallel programming (Computer science) , Linux , Abstract data types (Computer science) , Threads (Computer programs) , Computer programming
- Description: The availability of modern commodity multicore processors and multiprocessor computer systems has resulted in the widespread adoption of parallel computers in a variety of environments, ranging from the home to workstation and server environments in particular. Unfortunately, parallel programming is harder and requires more expertise than the traditional sequential programming model. The variety of tools and parallel programming models available to the programmer further complicates the issue. The primary goal of this research was to identify and describe a selection of parallel programming tools and techniques to aid novice parallel programmers in the process of developing efficient parallel C/C++ programs for the Linux platform. This was achieved by highlighting and describing the key concepts and hardware factors that affect parallel programming, providing a brief survey of commonly available software development tools and parallel programming models and libraries, and presenting structured approaches to software performance tuning and parallel programming. Finally, the performance of several parallel programming models and libraries was investigated, along with the programming effort required to implement solutions using the respective models. A quantitative research methodology was applied to the investigation of the performance and programming effort associated with the selected parallel programming models and libraries, which included automatic parallelisation by the compiler, Boost Threads, Cilk Plus, OpenMP, POSIX threads (Pthreads), and Threading Building Blocks (TBB). Additionally, the performance of the GNU C/C++ and Intel C/C++ compilers was examined. The results revealed that the choice of parallel programming model or library is dependent on the type of problem being solved and that there is no overall best choice for all classes of problem. However, the results also indicate that parallel programming models with higher levels of abstraction require less programming effort and provide similar performance compared to explicit threading models. The principle conclusion was that the problem analysis and parallel design are an important factor in the selection of the parallel programming model and tools, but that models with higher levels of abstractions, such as OpenMP and Threading Building Blocks, are favoured.
- Full Text:
- Date Issued: 2012
Photophysicochemical and photodynamic studies of phthalocyanines conjugated to selected drug delivery agents
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
Diagnosing organizational effectiveness in the tourism sector of Zanzibar
- Authors: Raja, Sanjay Kanji
- Date: 2012
- Subjects: Organizational effectiveness -- Zanzibar Management by objectives -- Zanzibar Tourism -- Zanzibar Tourism -- Management -- Zanzibar Job satisfaction -- Zanzibar Employee motivation -- Zanzibar
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:780 , http://hdl.handle.net/10962/d1003901
- Description: The tourism sector in Zanzibar Tanzania has emerged strongly in the past 15 years, helping the development of other Industries that support it. As a result, Industries such as telecommunication, IT, transport and hospitality have also emerged recently. It is, however, speculated that organizations in the tourism sector in Zanzibar generally lack the effective performance that is required of them to compete in the contemporary complex and turbulent market environment. This research thus set out to explore and diagnose the organizational effectiveness of the accommodation units of the tourism sector in Zanzibar. The research had specific objectives of diagnosing and finding the gap between the current and the optimal organizational performance in two particular units of accommodation as well as determining the factors affecting organizational performance in these units. The study furthermore set out to recommend implementation of suitable intervention activities to improve organizational performance in the units analyzed. In order to achieve the above objectives the research deployed an action research strategy with the Weisbord’s six box model as a framework to diagnose two five star grade accommodation units in Zanzibar. A qualitative method was used to collect data. Key findings of the research are briefly presented below: - The service output of the accommodation units analyzed was not very consistent and fell short of the expectation of their customers. This showed a gap in terms of the organizations’ performance. - Factors affecting organizational effectiveness were found to be mainly in the Purpose and Rewards functions of the organizations. - The specific areas in the Purpose function that appeared to have substantial problems were: -- Goals of the organization were not clearly stated -- Employees did not understand the purpose of the organization -- Employees were not involved in deciding their work unit goals -- Employees were not in agreement with the goals of their work units. -- Employees did not understand priorities of the organization The specific areas in the Reward function that appeared to have substantial problems were: -- The pay scale and benefits of the organization did not treat employees equitably. -- Employees felt that the salary they received was not commensurate with the jobs they performed. -- Not all tasks to be accomplished were associated with incentives. Following the diagnostics findings above, the research suggested the following intervention activities that could possibly help to address the above mentioned problems: - A Management by Objectives (MBO) process was suggested to redress the problems indicated in the Purpose function. This would help to set clearly agreed goals at all levels of the organizations. Employees and resources would then be directed towards achieving these goals that would enable the organizations to perform more effectively. - Revision of the current reward system was suggested to redress the problems indicated in the Reward function. The reward system should be implemented in a manner that creates a feeling of both internal as well as external (market) equity among employees. Furthermore, rewards should be linked to performance in order to direct behaviour and motivation among employees. The performance based reward system can also help to achieve the MBO process proposed above since rewards will be designated for achievement of individual, departmental and finally organizational objectives, thus increasing organizational effectiveness.
- Full Text:
- Date Issued: 2012
- Authors: Raja, Sanjay Kanji
- Date: 2012
- Subjects: Organizational effectiveness -- Zanzibar Management by objectives -- Zanzibar Tourism -- Zanzibar Tourism -- Management -- Zanzibar Job satisfaction -- Zanzibar Employee motivation -- Zanzibar
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:780 , http://hdl.handle.net/10962/d1003901
- Description: The tourism sector in Zanzibar Tanzania has emerged strongly in the past 15 years, helping the development of other Industries that support it. As a result, Industries such as telecommunication, IT, transport and hospitality have also emerged recently. It is, however, speculated that organizations in the tourism sector in Zanzibar generally lack the effective performance that is required of them to compete in the contemporary complex and turbulent market environment. This research thus set out to explore and diagnose the organizational effectiveness of the accommodation units of the tourism sector in Zanzibar. The research had specific objectives of diagnosing and finding the gap between the current and the optimal organizational performance in two particular units of accommodation as well as determining the factors affecting organizational performance in these units. The study furthermore set out to recommend implementation of suitable intervention activities to improve organizational performance in the units analyzed. In order to achieve the above objectives the research deployed an action research strategy with the Weisbord’s six box model as a framework to diagnose two five star grade accommodation units in Zanzibar. A qualitative method was used to collect data. Key findings of the research are briefly presented below: - The service output of the accommodation units analyzed was not very consistent and fell short of the expectation of their customers. This showed a gap in terms of the organizations’ performance. - Factors affecting organizational effectiveness were found to be mainly in the Purpose and Rewards functions of the organizations. - The specific areas in the Purpose function that appeared to have substantial problems were: -- Goals of the organization were not clearly stated -- Employees did not understand the purpose of the organization -- Employees were not involved in deciding their work unit goals -- Employees were not in agreement with the goals of their work units. -- Employees did not understand priorities of the organization The specific areas in the Reward function that appeared to have substantial problems were: -- The pay scale and benefits of the organization did not treat employees equitably. -- Employees felt that the salary they received was not commensurate with the jobs they performed. -- Not all tasks to be accomplished were associated with incentives. Following the diagnostics findings above, the research suggested the following intervention activities that could possibly help to address the above mentioned problems: - A Management by Objectives (MBO) process was suggested to redress the problems indicated in the Purpose function. This would help to set clearly agreed goals at all levels of the organizations. Employees and resources would then be directed towards achieving these goals that would enable the organizations to perform more effectively. - Revision of the current reward system was suggested to redress the problems indicated in the Reward function. The reward system should be implemented in a manner that creates a feeling of both internal as well as external (market) equity among employees. Furthermore, rewards should be linked to performance in order to direct behaviour and motivation among employees. The performance based reward system can also help to achieve the MBO process proposed above since rewards will be designated for achievement of individual, departmental and finally organizational objectives, thus increasing organizational effectiveness.
- Full Text:
- Date Issued: 2012
"Is more, less?" : insect-insect interactions in a biological control context using water hyacinth as a model
- Weyl, Philip Sebastian Richard
- Authors: Weyl, Philip Sebastian Richard
- Date: 2012
- Subjects: Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5724 , http://hdl.handle.net/10962/d1005410 , Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Description: Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.
- Full Text:
- Date Issued: 2012
- Authors: Weyl, Philip Sebastian Richard
- Date: 2012
- Subjects: Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5724 , http://hdl.handle.net/10962/d1005410 , Water hyacinth -- South Africa -- Eastern Cape , Water hyacinth -- Biological control -- South Africa -- Eastern Cape , Insects as biological pest control agents , Miridae -- South Africa -- Eastern Cape , Beetles -- South Africa -- Eastern Cape , Competition (Biology)
- Description: Interactions between insects have been shown to be important regulators of population abundances and dynamics as well as drivers of spatial segregation and distribution. These are important aspects of the ecology of insects used in biological control and may have implications for the overall success of a particular programme. In the history of biological control there has been a tendency to release a suite of agents against a weed, which in some cases has increased the level of success, while in others little change has been observed. In most of these cases the implications of increasing the level of complexity of the system is not taken into account and there is little research on the effect of releasing another agent into the system. A brief meta-analysis was done on all the biological control programmes initiated in South Africa. Emphasis was placed on multi-species releases and the effects that overlapping niches were having on the number of agents responsible for the success of a programme. Where overlapping niches were present among agents released the number of agents responsible for success was lower than the number established. Water hyacinth, Eichhornia crassipes (Martius) Solms-Laubach in South Africa has more arthropod agents released against it than anywhere else in the world, yet control has been variable. If the biology and host utilisation of all the agents against water hyacinth is considered, a definite overlap of niches is apparent in at least one life stage of all the agents. Therefore the probability of these insects interacting is high, especially if they are established at the same site in the field. Three of the insects released in South Africa have been selected to investigate possible interactions. They are Neochetina eichhorniae Warner, Neochetina bruchi Hustache and Eccritotarsus catarinensis (Carvalho). Y-tube olfactometer bioassays were used to measure responses of these insects to water hyacinth with prior feeding damage by either conspecifics or heterospecifics. This was done to determine whether olfactory cues played a role in host acceptability and avoidance of conspecifics or heterospecifics. The insects were given a choice between damaged and undamaged plants in various combinations. There was a significant preference for the undamaged plants when given a choice between undamaged and damaged plants. However when the insects were given a choice between two damaged plants there was no discrimination between heterospecific or conspecific damaged plants. This may indicate that there is little or no ecological cost for the insect to share a plant with other insects utilising a similar resource. Insect – insect interactions were investigated in a common garden plot experiment to measure the impact that pairwise combinations of the insect may have on their performance. There was a significant interaction between the mirid E. catarinensis and the weevil N. eichhorniae, with the weevil not performing as well when in combination with the mirid than when alone. Interestingly there was a negative interaction between the two weevil species when in combination, however it was impossible to determine which species was being affected if not both. None of the insects performed significantly better when in combination with another insect. A field study on Wriggleswade Dam in the Eastern Cape, South Africa was initiated to determine whether the relationship between the mirid E. catarinensis and the weevil N. eichhorniae could be determined in the field. The performance of the insects at the different sites in the field suggests that there was an interaction between the agents. This interaction did not limit the establishment of either insect at a site, but it did result in one insect dominating at a site over another. Interactions between the three species of insect tested in this thesis suggest that there are both negative and neutral relationships between them. A basic comparison between the insect performances from 15 sites around the country was done to determine if the spatial segregation observed in the field could be extrapolated to the natural South African situation. The interaction observed between N. eichhorniae and E. catarinensis does seem to extrapolate to the general South African situation where there is definite spatial segregation on a landscape level. The co–occurrence of the two Neochetina weevils at these sites suggests that the negative relationship observed between them in the common garden experiment does not extrapolate to the field. The results from this thesis suggest that the interactions between the agents tested would not limit establishment or have significant ramifications on performance. However, there may be spatial and temporal segregation of these species in the introduced range.
- Full Text:
- Date Issued: 2012
An assessment of caracal population density and human-predator conflict in the Winterberg, Eastern Cape, South Africa
- Authors: Smith, Emma Ruth
- Date: 2012
- Subjects: Felis -- South Africa -- Eastern Cape , Felis -- Effect of human beings on -- South Africa -- Eastern Cape , Predatory animals -- Control -- South Africa -- Eastern Cape , Wildlife depredation -- South Africa -- Eastern Cape , Human-animal relationships , Felis -- Conservation -- South Africa -- Eastern Cape , Felis -- Monitoring -- South Africa -- Eastern Cape , Animal populations -- Estimates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5644 , http://hdl.handle.net/10962/d1005326 , Felis -- South Africa -- Eastern Cape , Felis -- Effect of human beings on -- South Africa -- Eastern Cape , Predatory animals -- Control -- South Africa -- Eastern Cape , Wildlife depredation -- South Africa -- Eastern Cape , Human-animal relationships , Felis -- Conservation -- South Africa -- Eastern Cape , Felis -- Monitoring -- South Africa -- Eastern Cape , Animal populations -- Estimates
- Description: Human-wildlife conflict frequently involves carnivores, mainly because of their large home ranges and dietary requirements. As such, carnivores tend to be the first animals to be lost in human-dominated ecosystems. This is significant because the removal of carnivores can alter the functionality of ecosystems. However, the conservation of carnivores depends as much on the socio-political and socio-economic landscapes as it does on the ecological one. The consolidation of vast, un-fragmented conservation areas in Africa and the world is unlikely. Thus, unravelling the factors (both biological and sociological) responsible for and influencing human-predator conflict is critical for carnivore conservation. The Winterberg district in the Eastern Cape, South Africa has been a sheep (Ovis aries) farming stronghold for nearly 200 years. Consequently, conflict between farmers and predators is commonplace and depredation of livestock by caracals (Caracai caracal) remains a perennial problem. However, the extent of this human-predator conflict (including a reliable assessment of caracal density) has not been quantified. This study used camera trapping to estimate the density of caracals (a nonindividually recognisable species) in the Winterberg and a structured questionnaire to gauge the general attitudes of the farmers of the region. Caracal density was estimated to be 0.20 caracals/km². This estimate equates to a population of approximately 54 caracals across the entire district. Therefore, caracals do not appear to occur at high densities in the Winterberg. However, the survey of the residents of the Winterberg Conservancy revealed that predators were rated as the greatest problem faced by farmers in the area. Although not significant, it also showed that the size of a respondent's property and sheep mortality due to caracals had the greatest probability of affecting attitudes towards predators. The farmers lost less than 10% of their stock to caracal depredation on an annual basis. Therefore, the general perception that predators were the most important factor in stock loss in the area does not appear to be fully supported by my data. The Winterberg is a male-dominated, multigenerational society and it is likely this propagates certain perceptions towards predators which are a reflection of long-held family traditions and beliefs. Such situations can result in reactions which are disproportionate to the actual scale of the problem. However, my study was limited to a sub-set of the landowners in the Winterberg. Thus, more intensive assessments of caracal space use and community attitudes towards predators are recommended.
- Full Text:
- Date Issued: 2012
- Authors: Smith, Emma Ruth
- Date: 2012
- Subjects: Felis -- South Africa -- Eastern Cape , Felis -- Effect of human beings on -- South Africa -- Eastern Cape , Predatory animals -- Control -- South Africa -- Eastern Cape , Wildlife depredation -- South Africa -- Eastern Cape , Human-animal relationships , Felis -- Conservation -- South Africa -- Eastern Cape , Felis -- Monitoring -- South Africa -- Eastern Cape , Animal populations -- Estimates
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5644 , http://hdl.handle.net/10962/d1005326 , Felis -- South Africa -- Eastern Cape , Felis -- Effect of human beings on -- South Africa -- Eastern Cape , Predatory animals -- Control -- South Africa -- Eastern Cape , Wildlife depredation -- South Africa -- Eastern Cape , Human-animal relationships , Felis -- Conservation -- South Africa -- Eastern Cape , Felis -- Monitoring -- South Africa -- Eastern Cape , Animal populations -- Estimates
- Description: Human-wildlife conflict frequently involves carnivores, mainly because of their large home ranges and dietary requirements. As such, carnivores tend to be the first animals to be lost in human-dominated ecosystems. This is significant because the removal of carnivores can alter the functionality of ecosystems. However, the conservation of carnivores depends as much on the socio-political and socio-economic landscapes as it does on the ecological one. The consolidation of vast, un-fragmented conservation areas in Africa and the world is unlikely. Thus, unravelling the factors (both biological and sociological) responsible for and influencing human-predator conflict is critical for carnivore conservation. The Winterberg district in the Eastern Cape, South Africa has been a sheep (Ovis aries) farming stronghold for nearly 200 years. Consequently, conflict between farmers and predators is commonplace and depredation of livestock by caracals (Caracai caracal) remains a perennial problem. However, the extent of this human-predator conflict (including a reliable assessment of caracal density) has not been quantified. This study used camera trapping to estimate the density of caracals (a nonindividually recognisable species) in the Winterberg and a structured questionnaire to gauge the general attitudes of the farmers of the region. Caracal density was estimated to be 0.20 caracals/km². This estimate equates to a population of approximately 54 caracals across the entire district. Therefore, caracals do not appear to occur at high densities in the Winterberg. However, the survey of the residents of the Winterberg Conservancy revealed that predators were rated as the greatest problem faced by farmers in the area. Although not significant, it also showed that the size of a respondent's property and sheep mortality due to caracals had the greatest probability of affecting attitudes towards predators. The farmers lost less than 10% of their stock to caracal depredation on an annual basis. Therefore, the general perception that predators were the most important factor in stock loss in the area does not appear to be fully supported by my data. The Winterberg is a male-dominated, multigenerational society and it is likely this propagates certain perceptions towards predators which are a reflection of long-held family traditions and beliefs. Such situations can result in reactions which are disproportionate to the actual scale of the problem. However, my study was limited to a sub-set of the landowners in the Winterberg. Thus, more intensive assessments of caracal space use and community attitudes towards predators are recommended.
- Full Text:
- Date Issued: 2012
Optimistic science: the effectiveness of economic methodology in achieving objectivity
- Authors: Holl, Ryan
- Date: 2012
- Subjects: Economics -- Methodology , Social epistemology , Knowledge, Theory of -- Science , Objectivity -- Science , Science -- Methodology , Optimism
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1105 , http://hdl.handle.net/10962/d1013393
- Description: This thesis examines the extent to which optimism has a bearing on objectivity in scientific inquiry. It is not, however, a psychological level examination into objectivity. Rather, the discussion focuses on collective attitudes, whether in the form of science or a more general public opinion. In essence, sources of optimism at the fundamental level of scientific inquiry are articulated with a careful attempt to differentiate between attitudes about the subject (methodology) and the object of study. The antithetical thread of optimism versus pessimism is teased out with the use of a joint case study of liberalism and Stalinism. The idea of antithesis, however, is contrasted by the fact that, although mirror image ideologies, these collective attitudes share a common faith in progress (albeit through different social mechanisms). This faith in progress provides the basis for the crux of the thesis as it moves to discuss scientific methodology. There is general agreement on what good science should look like and the possibility of progressive science can be articulated. However, it is also possible to highlight the conditions for degenerative science and to further link this to a degenerative social totality in which democracy and social progress are undermined. Economics is used as a case study and it is argued that dogmatic notions on progress have proved to be a major stumbling block to objectivity in the discipline. Furthermore, the implications on the real world are serious.
- Full Text:
- Date Issued: 2012
- Authors: Holl, Ryan
- Date: 2012
- Subjects: Economics -- Methodology , Social epistemology , Knowledge, Theory of -- Science , Objectivity -- Science , Science -- Methodology , Optimism
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1105 , http://hdl.handle.net/10962/d1013393
- Description: This thesis examines the extent to which optimism has a bearing on objectivity in scientific inquiry. It is not, however, a psychological level examination into objectivity. Rather, the discussion focuses on collective attitudes, whether in the form of science or a more general public opinion. In essence, sources of optimism at the fundamental level of scientific inquiry are articulated with a careful attempt to differentiate between attitudes about the subject (methodology) and the object of study. The antithetical thread of optimism versus pessimism is teased out with the use of a joint case study of liberalism and Stalinism. The idea of antithesis, however, is contrasted by the fact that, although mirror image ideologies, these collective attitudes share a common faith in progress (albeit through different social mechanisms). This faith in progress provides the basis for the crux of the thesis as it moves to discuss scientific methodology. There is general agreement on what good science should look like and the possibility of progressive science can be articulated. However, it is also possible to highlight the conditions for degenerative science and to further link this to a degenerative social totality in which democracy and social progress are undermined. Economics is used as a case study and it is argued that dogmatic notions on progress have proved to be a major stumbling block to objectivity in the discipline. Furthermore, the implications on the real world are serious.
- Full Text:
- Date Issued: 2012
Foreign reference products in the registration of generic medicines in South Africa a case study
- Authors: Hwengwere, Eldinah
- Date: 2012
- Subjects: Generic drugs -- Law and legislation -- South Africa Case studies Generic drugs -- South Africa Case studies Drugs -- Law and legislation -- South Africa Case studies Pharmacy -- Law and legislation -- South Africa Case studies
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3762 , http://hdl.handle.net/10962/d1003240
- Description: Introduction: Due to the increase in healthcare costs, generic medicines have been adopted for used in both developed and developing countries. When a generic or ‘multisource interchangeable medicine’ is to be registered, studies that prove that the generic is equivalent to the Innovator Product (IP) are used. The generic medicine is required to prove that it will mirror the IP in terms of safety, quality and efficacy and, in South Africa, the Medicines Control Council (MCC) ensures that generic medicines meet these requirements. Generic medicines may be registered using bioequivalence data obtained from comparison with a domestic reference product (usually the local innovator product) or in certain cases, a foreign reference product (FRP). The bioequivalence data can either be from in vivo or in vitro studies. The MCC guidelines require that for modified release preparations, in vivo bioequivalence studies are done for approval of registration; the exception being if a proportionally higher dose has already been registered. No information is currently given to prescribers and dispensers or to the public about whether a generic product was registered against a foreign or domestic reference product. Aims and Objectives: 1.) To determine the number of generic medicines in a predetermined sample registered using a FRP as comparator and to document the transparency of pharmaceutical companies when approached to disclose information regarding the registration of these products. 2.) To describe and document the use of the Promotion of Access to Information Act (Act 2 of 2000) [PAIA] from the perspective of a ‘layperson’ in the context of medicines’ regulation, in both private and public bodies. Methods: 20 modified release and Biopharmaceutics Classification System (BCS) class IV products were selected from the ‘generics dictionary’ – a commercial publication – and letters were sent to the manufacturers of the products requesting information about the tests done to prove equivalence and whether they were performed against a domestic or foreign reference product. The same information was also requested from the MCC. The requests were all made using the Promotion of Access to Information Act (PAIA). Results: Nine companies were represented by the 20 products chosen. Information was obtained about thirteen products. Ten of these products were registered using FRPs. Four products were registered based only on comparative dissolution studies. Four companies provided the requested information, two companies responded by refusing the requests and three did not respond at all. The MCC refused the request for information even after an internal appeal was lodged. Conclusions: The Promotion of Access to information Act was unsuccessful in obtaining information from the public body, and partly successful in obtaining it from the private bodies. While the title of the Act seems to indicate that the Act can be used to obtain information as such, it only provides for access to specified records. The MCC and the pharmaceutical companies involved in the study were under no obligation to provide the information as the request had not complied with PAIA requirements. The use of FRPs for registration is a reality in the pharmaceutical industry in South Africa. Neither the public nor healthcare professionals who prescribe medicines or who are involved in dispensing generic medicines as substitutes are aware of whether or not a FRP has been used to register a generic. Interchangeability cannot necessarily be guaranteed if the reference product was not proven equivalent to the local innovator product. It is debatable as to whether or not this information would be of any particular benefit to members of the public. Prescribers may choose to write ‘no substitution’ on their prescriptions if they were unconvinced that an FRP is acceptable. This could have consequences for healthcare costs. Dispensers are the most vulnerable in South Africa as they are obliged by law to substitute generic medicines when innovator medicines have been prescribed. Dispensers’ views on the acceptability of the use of FRPs can be seen as irrelevant. In the end, as this study demonstrates, the only option in the present situation is to rely entirely on the MCC’s rigour in assessing applications for registration of generic medicines.
- Full Text:
- Date Issued: 2012
- Authors: Hwengwere, Eldinah
- Date: 2012
- Subjects: Generic drugs -- Law and legislation -- South Africa Case studies Generic drugs -- South Africa Case studies Drugs -- Law and legislation -- South Africa Case studies Pharmacy -- Law and legislation -- South Africa Case studies
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:3762 , http://hdl.handle.net/10962/d1003240
- Description: Introduction: Due to the increase in healthcare costs, generic medicines have been adopted for used in both developed and developing countries. When a generic or ‘multisource interchangeable medicine’ is to be registered, studies that prove that the generic is equivalent to the Innovator Product (IP) are used. The generic medicine is required to prove that it will mirror the IP in terms of safety, quality and efficacy and, in South Africa, the Medicines Control Council (MCC) ensures that generic medicines meet these requirements. Generic medicines may be registered using bioequivalence data obtained from comparison with a domestic reference product (usually the local innovator product) or in certain cases, a foreign reference product (FRP). The bioequivalence data can either be from in vivo or in vitro studies. The MCC guidelines require that for modified release preparations, in vivo bioequivalence studies are done for approval of registration; the exception being if a proportionally higher dose has already been registered. No information is currently given to prescribers and dispensers or to the public about whether a generic product was registered against a foreign or domestic reference product. Aims and Objectives: 1.) To determine the number of generic medicines in a predetermined sample registered using a FRP as comparator and to document the transparency of pharmaceutical companies when approached to disclose information regarding the registration of these products. 2.) To describe and document the use of the Promotion of Access to Information Act (Act 2 of 2000) [PAIA] from the perspective of a ‘layperson’ in the context of medicines’ regulation, in both private and public bodies. Methods: 20 modified release and Biopharmaceutics Classification System (BCS) class IV products were selected from the ‘generics dictionary’ – a commercial publication – and letters were sent to the manufacturers of the products requesting information about the tests done to prove equivalence and whether they were performed against a domestic or foreign reference product. The same information was also requested from the MCC. The requests were all made using the Promotion of Access to Information Act (PAIA). Results: Nine companies were represented by the 20 products chosen. Information was obtained about thirteen products. Ten of these products were registered using FRPs. Four products were registered based only on comparative dissolution studies. Four companies provided the requested information, two companies responded by refusing the requests and three did not respond at all. The MCC refused the request for information even after an internal appeal was lodged. Conclusions: The Promotion of Access to information Act was unsuccessful in obtaining information from the public body, and partly successful in obtaining it from the private bodies. While the title of the Act seems to indicate that the Act can be used to obtain information as such, it only provides for access to specified records. The MCC and the pharmaceutical companies involved in the study were under no obligation to provide the information as the request had not complied with PAIA requirements. The use of FRPs for registration is a reality in the pharmaceutical industry in South Africa. Neither the public nor healthcare professionals who prescribe medicines or who are involved in dispensing generic medicines as substitutes are aware of whether or not a FRP has been used to register a generic. Interchangeability cannot necessarily be guaranteed if the reference product was not proven equivalent to the local innovator product. It is debatable as to whether or not this information would be of any particular benefit to members of the public. Prescribers may choose to write ‘no substitution’ on their prescriptions if they were unconvinced that an FRP is acceptable. This could have consequences for healthcare costs. Dispensers are the most vulnerable in South Africa as they are obliged by law to substitute generic medicines when innovator medicines have been prescribed. Dispensers’ views on the acceptability of the use of FRPs can be seen as irrelevant. In the end, as this study demonstrates, the only option in the present situation is to rely entirely on the MCC’s rigour in assessing applications for registration of generic medicines.
- Full Text:
- Date Issued: 2012
Development of a hydraulic sub-model as part of a desktop environmental flow assessment method
- Authors: Desai, Ahmed Yacoob
- Date: 2012
- Subjects: Hydrologic models -- Research -- South Africa Hydraulic engineering -- South Africa Rivers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6041 , http://hdl.handle.net/10962/d1006200
- Description: Countries around the world have been developing ecological policies to protect their water resources and minimise the impacts of development on their river systems. The concept of ‘minimum flows’ was initially established as a solution but it did not provide sufficient protection as all elements of a flow regime were found to be important for the protection of the river ecosystem. “Environmental flows” were developed to determine these flow regimes to maintain a river in some defined ecological condition. Rapid, initial estimates of the quantity component of environmental flows may be determined using the Desktop Reserve Model in South Africa. However, the Desktop Reserve Model is dependent upon the characteristics of the reference natural hydrology used. The advancements in hydraulic and ecological relationships from the past decade have prompted the development of a Revised Desktop Reserve Model (RDRM) that would incorporate these relationships. The research in this thesis presents the development of the hydraulic sub-model for the RDRM. The hydraulic sub-model was designed to produce a realistic representation of the hydraulic conditions using hydraulic parameters/characteristics from readily available information for any part of South Africa. Hydraulic data from past EWR studies were used to estimate the hydraulic parameters. These estimated hydraulic parameters were used to develop hydraulic estimation relationships and these relationships were developed based on a combination of regression and rule-based procedures. The estimation relationships were incorporated into the hydraulic sub-model of the integrated RDRM and assessments of the hydraulic outputs and EWR results were undertaken to assess the ‘applicability’ of the hydraulic sub-model. The hydraulic sub-model was assessed to be at a stage where it can satisfactorily be incorporated in the RDRM and that it is adequately robust in many situations. Recommendations for future work include the refinement of estimation of the channel forming discharge or the use of spatial imagery to check the maximum channel width estimation. It is also proposed that a future version of the hydraulic sub-model could include flow regime change impacts on channel geomorphology and sedimentology so that flow management scenarios can be more effectively assessed.
- Full Text:
- Date Issued: 2012
- Authors: Desai, Ahmed Yacoob
- Date: 2012
- Subjects: Hydrologic models -- Research -- South Africa Hydraulic engineering -- South Africa Rivers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6041 , http://hdl.handle.net/10962/d1006200
- Description: Countries around the world have been developing ecological policies to protect their water resources and minimise the impacts of development on their river systems. The concept of ‘minimum flows’ was initially established as a solution but it did not provide sufficient protection as all elements of a flow regime were found to be important for the protection of the river ecosystem. “Environmental flows” were developed to determine these flow regimes to maintain a river in some defined ecological condition. Rapid, initial estimates of the quantity component of environmental flows may be determined using the Desktop Reserve Model in South Africa. However, the Desktop Reserve Model is dependent upon the characteristics of the reference natural hydrology used. The advancements in hydraulic and ecological relationships from the past decade have prompted the development of a Revised Desktop Reserve Model (RDRM) that would incorporate these relationships. The research in this thesis presents the development of the hydraulic sub-model for the RDRM. The hydraulic sub-model was designed to produce a realistic representation of the hydraulic conditions using hydraulic parameters/characteristics from readily available information for any part of South Africa. Hydraulic data from past EWR studies were used to estimate the hydraulic parameters. These estimated hydraulic parameters were used to develop hydraulic estimation relationships and these relationships were developed based on a combination of regression and rule-based procedures. The estimation relationships were incorporated into the hydraulic sub-model of the integrated RDRM and assessments of the hydraulic outputs and EWR results were undertaken to assess the ‘applicability’ of the hydraulic sub-model. The hydraulic sub-model was assessed to be at a stage where it can satisfactorily be incorporated in the RDRM and that it is adequately robust in many situations. Recommendations for future work include the refinement of estimation of the channel forming discharge or the use of spatial imagery to check the maximum channel width estimation. It is also proposed that a future version of the hydraulic sub-model could include flow regime change impacts on channel geomorphology and sedimentology so that flow management scenarios can be more effectively assessed.
- Full Text:
- Date Issued: 2012
Investigating the impact of brand reputation on brand architecture strategies : a study on a South African automotive company
- Authors: Waddington, Andrew John
- Date: 2012
- Subjects: Branding (Marketing) -- Case studies Automobile industry and trade -- South Africa -- Case studies Toyota Jidōsha Kōgyō Kabushiki Kaisha -- Case studies Automobiles -- Marketing -- Case studies Product management -- Case studies Branding (Marketing) -- Management -- Case studies Corporate image -- Management -- Case studies Brand name products -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1179 , http://hdl.handle.net/10962/d1002796
- Description: The brand architecture of an organisation has become increasingly important to global management and marketing professionals, as it deals with structures and designs of brands which are constantly influenced by a changing environment. The market realities and changes brands face continuously impact the reputation of the brand, which is critical to sustain competitive advantage. The primary purpose of the study was to investigate the impact brand reputation has on brand architecture strategies, and an automotive company was chosen as the focus of the research. This research aims to help managers, marketers and brand owners make informative decisions regarding the brand architecture of a company. A quantitative content analysis methodology was used along with a webpage keyword counting application (WebWords). The application was used based on the principles outlined by Corporate Brand and Reputation Analysis (COBRA), which uses a four step progressive filtering process in filtering traditional and consumer generated media. The results from WebWords were then aligned to the brand architecture strategies from the brand relationship spectrum (BRS) to gain insight as to which of the strategies from the BRS were most vulnerable to reputational damage. The study found that the branded house and sub-brand strategies were most vulnerable to reputational damage based on the number reputational hits received. The connection between the master brand and the sub-brands could cause both brands to be affected should any reputational issues arise.
- Full Text:
- Date Issued: 2012
- Authors: Waddington, Andrew John
- Date: 2012
- Subjects: Branding (Marketing) -- Case studies Automobile industry and trade -- South Africa -- Case studies Toyota Jidōsha Kōgyō Kabushiki Kaisha -- Case studies Automobiles -- Marketing -- Case studies Product management -- Case studies Branding (Marketing) -- Management -- Case studies Corporate image -- Management -- Case studies Brand name products -- South Africa -- Case studies
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1179 , http://hdl.handle.net/10962/d1002796
- Description: The brand architecture of an organisation has become increasingly important to global management and marketing professionals, as it deals with structures and designs of brands which are constantly influenced by a changing environment. The market realities and changes brands face continuously impact the reputation of the brand, which is critical to sustain competitive advantage. The primary purpose of the study was to investigate the impact brand reputation has on brand architecture strategies, and an automotive company was chosen as the focus of the research. This research aims to help managers, marketers and brand owners make informative decisions regarding the brand architecture of a company. A quantitative content analysis methodology was used along with a webpage keyword counting application (WebWords). The application was used based on the principles outlined by Corporate Brand and Reputation Analysis (COBRA), which uses a four step progressive filtering process in filtering traditional and consumer generated media. The results from WebWords were then aligned to the brand architecture strategies from the brand relationship spectrum (BRS) to gain insight as to which of the strategies from the BRS were most vulnerable to reputational damage. The study found that the branded house and sub-brand strategies were most vulnerable to reputational damage based on the number reputational hits received. The connection between the master brand and the sub-brands could cause both brands to be affected should any reputational issues arise.
- Full Text:
- Date Issued: 2012
The effects of sustained attention, workload and task-related fatigue on physiological measures and performance during a tracking task
- Authors: De Gray Birch, Casey
- Date: 2012
- Subjects: Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5120 , http://hdl.handle.net/10962/d1005198 , Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Description: Despite extensive research into the concept of mental fatigue there is as yet no “gold standard” definition or measurement technique available. Because of this a large amount of fatigue-related errors are still seen in the workplace. The complexity of the problem lies with the inability to directly measure mental processes as well as the various endogenous and exogenous factors that interact to produce the experienced fatigue. Fatigue has been divided into sleep-related and task-related fatigue; however the task-related aspect is evident both during normal waking hours as well as during periods of sleep deprivation, therefore this aspect is considered important in the understanding of fatigue in general. The concept of task-related fatigue has further been divided into active and passive fatigue states; however differentiation between the two requires careful consideration. Various physiological measures have been employed in an attempt to gain a better understanding of the mechanisms involved in the generation of fatigue, however often studies have produced dissociating results. The current study considered the task-related fatigue elicited by a tracking task requiring sustained attention, in order to evaluate the usefulness of various cardiovascular and oculomotor measures as indicators of fatigue. A secondary aim was to determine whether the behavioural and physiological parameter responses could be used to infer the type of fatigue incurred (i.e. an active versus passive fatigue state) as well as the energetical mechanisms involved during task performance. A simple driving simulator task was used as the main tracking task, requiring constant attention and concentration. This task was performed for approximately two hours. Three experimental groups (consisting of 14 subjects each) were used: a control group that performed the tracking task only, a group that performed a five minute auditory memory span task concurrently with the driving task after every 20 minutes of pure driving, and a group that performed a visual choice reaction task for five minutes following every 20 minute driving period. The secondary tasks were employed in order to evaluate the extent of resource allocation as well as arousal level. Performance measures included various driving performance parameters, as well as secondary task performance. Physiological measures included heart rate frequency (HR) and various time- and frequency-domain heart rate variability (HRV)parameters, pupil dilation, blink frequency and duration, fixations, and saccadic parameters as well as critical flicker fusion frequency (CFFF). The Borg CR-10 scale was used to evaluate subjective fatigue during the task, and the NASA-TLX was completed following the task. A decline in driving performance over time was supplemented by measures such as HR, HRV and pupil dilation indicating an increase in parasympathetic activity (or a reduction in arousal). An increase in blink frequency was considered as a sign of withdrawal of attentional resources over time. Longer and faster saccades were also evident over time, coupled with shorter fixations. With regards to the secondary task influence, the choice RT task did not affect any behavioural or physiological parameters, thereby contesting the active fatigue theory of resource depletion, as well as implying that the increase in demand for the same resources used by the primary task was insufficient to affect the state of the subjects. The increased load elicited by the memory span task improved driving performance and increased measures of HR, HRV, pupil dilation and blink frequency. Some of these measures produced opposite effects to what was expected; an attempt to explain the dissociation of the various physiological parameters was expressed in terms of arousal, effort and resource theories. Overall, the results indicate that the fatigue and/or reduced arousal accompanying a monotonous sustained attention task can, to some degree, be alleviated through intermittent performance of a secondary task engaging mental resources other than the ones used for the primary task. The degree to which such a task is beneficial, however, requires careful consideration as while an immediate increase in arousal and primary task performance is noted, the impact of the task on general attentional resources may be detrimental in the case of reacting should an emergency situation occur.
- Full Text:
- Date Issued: 2012
- Authors: De Gray Birch, Casey
- Date: 2012
- Subjects: Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5120 , http://hdl.handle.net/10962/d1005198 , Fatigue -- Physiological aspects -- Research , Attention -- Physiological aspects -- Research , Human engineering -- Research
- Description: Despite extensive research into the concept of mental fatigue there is as yet no “gold standard” definition or measurement technique available. Because of this a large amount of fatigue-related errors are still seen in the workplace. The complexity of the problem lies with the inability to directly measure mental processes as well as the various endogenous and exogenous factors that interact to produce the experienced fatigue. Fatigue has been divided into sleep-related and task-related fatigue; however the task-related aspect is evident both during normal waking hours as well as during periods of sleep deprivation, therefore this aspect is considered important in the understanding of fatigue in general. The concept of task-related fatigue has further been divided into active and passive fatigue states; however differentiation between the two requires careful consideration. Various physiological measures have been employed in an attempt to gain a better understanding of the mechanisms involved in the generation of fatigue, however often studies have produced dissociating results. The current study considered the task-related fatigue elicited by a tracking task requiring sustained attention, in order to evaluate the usefulness of various cardiovascular and oculomotor measures as indicators of fatigue. A secondary aim was to determine whether the behavioural and physiological parameter responses could be used to infer the type of fatigue incurred (i.e. an active versus passive fatigue state) as well as the energetical mechanisms involved during task performance. A simple driving simulator task was used as the main tracking task, requiring constant attention and concentration. This task was performed for approximately two hours. Three experimental groups (consisting of 14 subjects each) were used: a control group that performed the tracking task only, a group that performed a five minute auditory memory span task concurrently with the driving task after every 20 minutes of pure driving, and a group that performed a visual choice reaction task for five minutes following every 20 minute driving period. The secondary tasks were employed in order to evaluate the extent of resource allocation as well as arousal level. Performance measures included various driving performance parameters, as well as secondary task performance. Physiological measures included heart rate frequency (HR) and various time- and frequency-domain heart rate variability (HRV)parameters, pupil dilation, blink frequency and duration, fixations, and saccadic parameters as well as critical flicker fusion frequency (CFFF). The Borg CR-10 scale was used to evaluate subjective fatigue during the task, and the NASA-TLX was completed following the task. A decline in driving performance over time was supplemented by measures such as HR, HRV and pupil dilation indicating an increase in parasympathetic activity (or a reduction in arousal). An increase in blink frequency was considered as a sign of withdrawal of attentional resources over time. Longer and faster saccades were also evident over time, coupled with shorter fixations. With regards to the secondary task influence, the choice RT task did not affect any behavioural or physiological parameters, thereby contesting the active fatigue theory of resource depletion, as well as implying that the increase in demand for the same resources used by the primary task was insufficient to affect the state of the subjects. The increased load elicited by the memory span task improved driving performance and increased measures of HR, HRV, pupil dilation and blink frequency. Some of these measures produced opposite effects to what was expected; an attempt to explain the dissociation of the various physiological parameters was expressed in terms of arousal, effort and resource theories. Overall, the results indicate that the fatigue and/or reduced arousal accompanying a monotonous sustained attention task can, to some degree, be alleviated through intermittent performance of a secondary task engaging mental resources other than the ones used for the primary task. The degree to which such a task is beneficial, however, requires careful consideration as while an immediate increase in arousal and primary task performance is noted, the impact of the task on general attentional resources may be detrimental in the case of reacting should an emergency situation occur.
- Full Text:
- Date Issued: 2012
A baculovirus-mediated expression system for the analysis of HaSV RNA packaging
- Authors: Mendes, Adriano
- Date: 2012
- Subjects: RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4025 , http://hdl.handle.net/10962/d1004085 , RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Description: The Helicoverpa armigera stunt virus (HaSV) is a member of a family of small nonenveloped (+) ssRNA insect viruses currently known as the Tetraviridae. This family is unique in terms of the T=4 quasi-symmetry of its capsid particles and the unusually narrow host range and tissue tropism. Assembly of tetraviral particles has been well characterised and involves the combination of 240 copies of a single capsid precursor protein (VCap) into a procapsid followed by autoproteolytic cleavage to yield the major (β) and minor (γ) capsid subunits within the mature particle. HaSV has two genomic RNAs, RNA 1 encoding the replicase and RNA 2 encoding VCap and p17, the ORF of which lies upstream of and overlaping with the 5’ end of the VCap ORF. Prior to this study, Vlok (2009) used a plasmid expression system to study RNA packaging in HaSV VLPs assembled in Spodoptera frugiperda 9 (Sf9) cells co-expressing p17 and VCap. The study showed that the p17 ORF was required for the packaging of RNA 2 during capsid assembly but it was unclear whether p17 expression was required for packaging. In addition, expression from the transfected plasmids was sub-optimal affecting both the yield of VLPs and the detection of p17. The aim of this study was to use the plasmid system to test whether p17 expression was required for plasmid-derived VLP RNA packaging and then develop a baculovirus-mediated system to test this hypothesis. By using a plasmid in which the start codon of p17 was mutated, it was shown that p17 expression was required for RNA 2 packaging into plasmid-VLPs. For the baculovirus system, four recombinant baculoviruses based upon the pFastBac Dual expression system, were constructed. These included Bac20, expressing wild type RNA 2, Bac21, RNA 2 with p17 silenced, Bac23, RNA 2 and p17 expressed on a separate transcript and Bac24, RNA 2 with p17 silenced plus p17 expressed on a separate transcript. Assembly of VLPs was more efficient using the baculovirus expression system and p17 expression was observed in cells infected with Bac20, Bac23 and Bac24, but not Bac21. In contrast to the plasmid-VLPs, bac-VLPs did not require p17 for the encapsidation of RNA 2. In addition to RNA 2, Bac23 and Bac24 packaged the p17 mRNA transcribed separately from RNA 2. This insinuated that bac-VLPs may be packaging RNA non-selectively. It was proposed that p17 may play a role in packaging in an RNA-limiting environment (plasmid system) but functioned differently when viral RNA was in excess (baculovirus system). This data points to the importance of developing a replication system for the analysis of the packaging pathways of these viruses and this study has laid down the foundations for such a system in which RNA 1 and RNA 2 can be introduced into a single cell by means of a single recombinant virus.
- Full Text:
- Date Issued: 2012
- Authors: Mendes, Adriano
- Date: 2012
- Subjects: RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4025 , http://hdl.handle.net/10962/d1004085 , RNA , Baculoviruses , Helicoverpa armigera , Plasmids
- Description: The Helicoverpa armigera stunt virus (HaSV) is a member of a family of small nonenveloped (+) ssRNA insect viruses currently known as the Tetraviridae. This family is unique in terms of the T=4 quasi-symmetry of its capsid particles and the unusually narrow host range and tissue tropism. Assembly of tetraviral particles has been well characterised and involves the combination of 240 copies of a single capsid precursor protein (VCap) into a procapsid followed by autoproteolytic cleavage to yield the major (β) and minor (γ) capsid subunits within the mature particle. HaSV has two genomic RNAs, RNA 1 encoding the replicase and RNA 2 encoding VCap and p17, the ORF of which lies upstream of and overlaping with the 5’ end of the VCap ORF. Prior to this study, Vlok (2009) used a plasmid expression system to study RNA packaging in HaSV VLPs assembled in Spodoptera frugiperda 9 (Sf9) cells co-expressing p17 and VCap. The study showed that the p17 ORF was required for the packaging of RNA 2 during capsid assembly but it was unclear whether p17 expression was required for packaging. In addition, expression from the transfected plasmids was sub-optimal affecting both the yield of VLPs and the detection of p17. The aim of this study was to use the plasmid system to test whether p17 expression was required for plasmid-derived VLP RNA packaging and then develop a baculovirus-mediated system to test this hypothesis. By using a plasmid in which the start codon of p17 was mutated, it was shown that p17 expression was required for RNA 2 packaging into plasmid-VLPs. For the baculovirus system, four recombinant baculoviruses based upon the pFastBac Dual expression system, were constructed. These included Bac20, expressing wild type RNA 2, Bac21, RNA 2 with p17 silenced, Bac23, RNA 2 and p17 expressed on a separate transcript and Bac24, RNA 2 with p17 silenced plus p17 expressed on a separate transcript. Assembly of VLPs was more efficient using the baculovirus expression system and p17 expression was observed in cells infected with Bac20, Bac23 and Bac24, but not Bac21. In contrast to the plasmid-VLPs, bac-VLPs did not require p17 for the encapsidation of RNA 2. In addition to RNA 2, Bac23 and Bac24 packaged the p17 mRNA transcribed separately from RNA 2. This insinuated that bac-VLPs may be packaging RNA non-selectively. It was proposed that p17 may play a role in packaging in an RNA-limiting environment (plasmid system) but functioned differently when viral RNA was in excess (baculovirus system). This data points to the importance of developing a replication system for the analysis of the packaging pathways of these viruses and this study has laid down the foundations for such a system in which RNA 1 and RNA 2 can be introduced into a single cell by means of a single recombinant virus.
- Full Text:
- Date Issued: 2012
Emancipatory spaces in the post-colony : South Africa and the case for AbM and UPM
- Authors: Tselapedi, Thapelo
- Date: 2012
- Subjects: Local government -- South Africa -- Grahamstown Postcolonialism -- South Africa -- Grahamstown Apartheid -- South Africa Civil society -- South Africa -- Grahamstown Social movements -- South Africa -- Grahamstown South Africa -- Economic conditions -- 1991- South Africa -- Economic policy South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2839 , http://hdl.handle.net/10962/d1004451
- Description: This thesis is about the relationship between local government, grassroots organisations and the organisation of power resulting from the interaction of the two. Exploring this relationship this thesis investigates whether the actions of grassroots movements can bring local government in line with their developmental role as accorded to them by the Constitution. The assumption embedded in this question is that the current balance of power at the local level exists outside of the service of the historically disadvantaged. Following on from that, the thesis explores, through different modes of analysis, theoretical and historical, the policy and constitutional framework for local government, and then it unravels the context set by the political economy of South Africa. The aim is to make a significant attempt at understanding the possible implications of the interventions grassroots movements make in the public space. The thesis does this also by looking at the strengths and weaknesses of the strategies of the UDF to makes an assessment of the possible endurance of post-apartheid grassroots movements. Since civil society ‘suffers’ from nationalist politics, with its own corporatist institutions, the thesis searches deep within or arguably 'outside of civil society', subjecting AbM and UPM to academic critique, to see how movements embedded among the poor and carrying the political instrument of anger and marginalisation, can dislodge the power of capital. More importantly, the thesis situates the post-apartheid moment within postcolonial politics; navigating through the legacy of Colonialism of a Special Type (CSP), the thesis explores the limits and opportunities at the disposal of grassroots movements. From a different perspective, the thesis is an examination of the organisation and movement of power and the spaces within which power and ideas are contested. Drawing on the political and economic engagements, dubbed the Dar Es Salaam debates, in the 1970’s and 1980’s spurred on by Issa Shivji, the late Prof Dani Wadada Nabudere and Mahmood Mandani, the conclusions of this thesis develops these engagements, essentially making a case for the continued centrality of the post-apartheid state. However, the thesis also asserts the indubitable role that both grassroots movements and civil society need to play, not necessarily in the democratisation of the state, though that goes without saying, but in taking the post-colonial state on its own terms. Consequently, the thesis puts forward the idea that issue-based mobilisation does exactly this, and in the manner that acknowledges the state’s centrality and makes paramount the self-organisation (popular assemblies) of ordinary people in public affairs. The thesis categorically concludes that the centrality of the post-apartheid state and its progressive outlook (constitutional values) is contingent on organs of popular assemblies which need to take the state on its (progressive) terms.
- Full Text:
- Date Issued: 2012
- Authors: Tselapedi, Thapelo
- Date: 2012
- Subjects: Local government -- South Africa -- Grahamstown Postcolonialism -- South Africa -- Grahamstown Apartheid -- South Africa Civil society -- South Africa -- Grahamstown Social movements -- South Africa -- Grahamstown South Africa -- Economic conditions -- 1991- South Africa -- Economic policy South Africa -- Politics and government -- 1994-
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2839 , http://hdl.handle.net/10962/d1004451
- Description: This thesis is about the relationship between local government, grassroots organisations and the organisation of power resulting from the interaction of the two. Exploring this relationship this thesis investigates whether the actions of grassroots movements can bring local government in line with their developmental role as accorded to them by the Constitution. The assumption embedded in this question is that the current balance of power at the local level exists outside of the service of the historically disadvantaged. Following on from that, the thesis explores, through different modes of analysis, theoretical and historical, the policy and constitutional framework for local government, and then it unravels the context set by the political economy of South Africa. The aim is to make a significant attempt at understanding the possible implications of the interventions grassroots movements make in the public space. The thesis does this also by looking at the strengths and weaknesses of the strategies of the UDF to makes an assessment of the possible endurance of post-apartheid grassroots movements. Since civil society ‘suffers’ from nationalist politics, with its own corporatist institutions, the thesis searches deep within or arguably 'outside of civil society', subjecting AbM and UPM to academic critique, to see how movements embedded among the poor and carrying the political instrument of anger and marginalisation, can dislodge the power of capital. More importantly, the thesis situates the post-apartheid moment within postcolonial politics; navigating through the legacy of Colonialism of a Special Type (CSP), the thesis explores the limits and opportunities at the disposal of grassroots movements. From a different perspective, the thesis is an examination of the organisation and movement of power and the spaces within which power and ideas are contested. Drawing on the political and economic engagements, dubbed the Dar Es Salaam debates, in the 1970’s and 1980’s spurred on by Issa Shivji, the late Prof Dani Wadada Nabudere and Mahmood Mandani, the conclusions of this thesis develops these engagements, essentially making a case for the continued centrality of the post-apartheid state. However, the thesis also asserts the indubitable role that both grassroots movements and civil society need to play, not necessarily in the democratisation of the state, though that goes without saying, but in taking the post-colonial state on its own terms. Consequently, the thesis puts forward the idea that issue-based mobilisation does exactly this, and in the manner that acknowledges the state’s centrality and makes paramount the self-organisation (popular assemblies) of ordinary people in public affairs. The thesis categorically concludes that the centrality of the post-apartheid state and its progressive outlook (constitutional values) is contingent on organs of popular assemblies which need to take the state on its (progressive) terms.
- Full Text:
- Date Issued: 2012
Comparative biogeography and ecology of freshwater fishes in the Breede and associated river systems, South Africa
- Authors: Chakona, Albert
- Date: 2012
- Subjects: Freshwater fishes -- South Africa -- Breede River , Freshwater fishes -- South Africa -- Geographical distribution , Freshwater fishes -- Ecology , Feshwater fishes -- Genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5372 , http://hdl.handle.net/10962/d1015694
- Description: Distribution patterns and levels of genetic diversity in extant taxa are a product of complex palaeogeographic processes and climatic oscillations as well as the species’ intrinsic ecological adaptations. The Cape Floristic Region of South Africa presents a unique system for studying the processes that promote species diversification and distribution patterns. This region has a high degree of endemism of both terrestrial and aquatic biota and is clearly isolated from neighbouring areas by the Cape Fold Mountains and the Great Escarpment. The objective of this study was to firstly examine the ecology of freshwater fishes belonging to the genera Galaxias, Pseudobarbus and Sandelia in the south-western CFR. This was followed by an assessment of the genetic diversity of these taxa. Unique lineages were identified and their distribution was mapped. The work aimed to explore the role of the region’s complex palaeogeographic and climatic history as well as the role of the species’ ecological adaptations in driving lineage diversification and shaping contemporary distribution patterns. The four main components of the study can be summarised as follows: 1. Habitat associations of three widely distributed lineages of Galaxias zebratus Pseudobarbus burchelli and Sandelia capensis were evaluated at multiple localities in minimally disturbed mountain tributaries of the Breede, Duiwenhoks and Goukou River systems. The lineages have distinct habitat associations which were related to differences in their morphological traits. The slender-bodied Galaxias ‘nebula’ and the fusiform-shaped Pseudobarbus ‘Breede’ are capable of exploiting upper reaches with faster water velocity. By contrast, the laterally compressed Sandelia ‘eastern’ is restricted to lower reaches, making this lineage more susceptible to a wide array of impacts. 2. A recently discovered lineage of Galaxias zebratus, (Galaxias ‘nebula’), was found to be capable of tolerating emersion for a prolonged period of time. This is the first time that such capabilities have been documented in an African galaxiid. These adaptations have implications for the interpretation of Galaxias ‘nebula’s wide distribution range. 3. The phylogeography of Galaxias ‘nebula’ across its entire distribution range was investigated using two mitochondrial genes (cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b)). This lineage has a complex evolutionary history that was influenced by both intrinsic and extrinsic factors. Rare events such as episodic drainage connections during Pleistocene and Holocene pluvial periods, possibly augmented by river confluences during periods of lower sea-levels and river capture events seem to be the most credible explanation for the extensive contemporary distribution and the relatively shallow genetic divergence between different river systems. 4. Mitochondrial cyt b sequences were used (i) to assess genetic diversity in G. zebratus, P. burchelli and S. capensis from the south-western CFR and (ii) to determine the roles of intrinsic ecological adaptations and extrinsic landscape and climatic changes in promoting genetic diversification and shaping present day distribution patterns of lineages in the three taxa. Marine incursions during periods of major sea-level transgressions are proposed to have isolated populations in upland refugia, thereby driving allopatric divergence in these species. Subsequent connections of rivers during wetter periods and lower sea-levels are proposed to have facilitated post-speciation dispersal of lineages to attain present day distribution patterns. While detailed morphological studies and further genetic analysis are needed to substantiate the taxonomic status of the newly discovered lineages of Galaxias zebratus, Pseudobarbus burchelli and Sandelia capensis, results of the present study indicate that the south-western CFR represents a previously unrecognised centre of freshwater fish diversity and microendemism in the broader Cape Floristic Region. Accurate identification of lineages and comprehensive mapping of their distribution is a fundamental pre-requisite for ecological studies, assessing conservation status and implementation of appropriate conservation measures.
- Full Text:
- Date Issued: 2012
- Authors: Chakona, Albert
- Date: 2012
- Subjects: Freshwater fishes -- South Africa -- Breede River , Freshwater fishes -- South Africa -- Geographical distribution , Freshwater fishes -- Ecology , Feshwater fishes -- Genetics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5372 , http://hdl.handle.net/10962/d1015694
- Description: Distribution patterns and levels of genetic diversity in extant taxa are a product of complex palaeogeographic processes and climatic oscillations as well as the species’ intrinsic ecological adaptations. The Cape Floristic Region of South Africa presents a unique system for studying the processes that promote species diversification and distribution patterns. This region has a high degree of endemism of both terrestrial and aquatic biota and is clearly isolated from neighbouring areas by the Cape Fold Mountains and the Great Escarpment. The objective of this study was to firstly examine the ecology of freshwater fishes belonging to the genera Galaxias, Pseudobarbus and Sandelia in the south-western CFR. This was followed by an assessment of the genetic diversity of these taxa. Unique lineages were identified and their distribution was mapped. The work aimed to explore the role of the region’s complex palaeogeographic and climatic history as well as the role of the species’ ecological adaptations in driving lineage diversification and shaping contemporary distribution patterns. The four main components of the study can be summarised as follows: 1. Habitat associations of three widely distributed lineages of Galaxias zebratus Pseudobarbus burchelli and Sandelia capensis were evaluated at multiple localities in minimally disturbed mountain tributaries of the Breede, Duiwenhoks and Goukou River systems. The lineages have distinct habitat associations which were related to differences in their morphological traits. The slender-bodied Galaxias ‘nebula’ and the fusiform-shaped Pseudobarbus ‘Breede’ are capable of exploiting upper reaches with faster water velocity. By contrast, the laterally compressed Sandelia ‘eastern’ is restricted to lower reaches, making this lineage more susceptible to a wide array of impacts. 2. A recently discovered lineage of Galaxias zebratus, (Galaxias ‘nebula’), was found to be capable of tolerating emersion for a prolonged period of time. This is the first time that such capabilities have been documented in an African galaxiid. These adaptations have implications for the interpretation of Galaxias ‘nebula’s wide distribution range. 3. The phylogeography of Galaxias ‘nebula’ across its entire distribution range was investigated using two mitochondrial genes (cytochrome c oxidase subunit I (COI) and cytochrome b (cyt b)). This lineage has a complex evolutionary history that was influenced by both intrinsic and extrinsic factors. Rare events such as episodic drainage connections during Pleistocene and Holocene pluvial periods, possibly augmented by river confluences during periods of lower sea-levels and river capture events seem to be the most credible explanation for the extensive contemporary distribution and the relatively shallow genetic divergence between different river systems. 4. Mitochondrial cyt b sequences were used (i) to assess genetic diversity in G. zebratus, P. burchelli and S. capensis from the south-western CFR and (ii) to determine the roles of intrinsic ecological adaptations and extrinsic landscape and climatic changes in promoting genetic diversification and shaping present day distribution patterns of lineages in the three taxa. Marine incursions during periods of major sea-level transgressions are proposed to have isolated populations in upland refugia, thereby driving allopatric divergence in these species. Subsequent connections of rivers during wetter periods and lower sea-levels are proposed to have facilitated post-speciation dispersal of lineages to attain present day distribution patterns. While detailed morphological studies and further genetic analysis are needed to substantiate the taxonomic status of the newly discovered lineages of Galaxias zebratus, Pseudobarbus burchelli and Sandelia capensis, results of the present study indicate that the south-western CFR represents a previously unrecognised centre of freshwater fish diversity and microendemism in the broader Cape Floristic Region. Accurate identification of lineages and comprehensive mapping of their distribution is a fundamental pre-requisite for ecological studies, assessing conservation status and implementation of appropriate conservation measures.
- Full Text:
- Date Issued: 2012