Ecology and degree of specialization of South African milkweeds with diverse pollination systems
- Authors: Coombs, Gareth
- Date: 2010
- Subjects: Milkweeds -- South Africa Milkweeds -- South Africa -- Ecology Milkweeds -- South Africa -- Pollination Allee effect Self-pollination Pollination by insects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4189 , http://hdl.handle.net/10962/d1003758
- Description: Like orchids, the complexity of flowers found in asclepiads (Asclepiadoideae, Apocynaceae) and the fact that pollen is presented as pollinaria, offers excellent opportunities to study various aspects of plant-pollinator interactions. In this thesis I investigated two broad themes: ecological aspects of the pollination biology of hymenopteran and fly-pollinated asclepiads as well as the degree of specialization to certain pollinators in these species. Colonizing plants often reproduce through self-pollination, or have highly generalized pollination systems, or both. These characteristics facilitate establishment in small founding populations and generates the prediction that reproductive success should be independent of population size in these species. Chapter one examines the pollination biology of Gomphocarpus physocarpus, an indigenous, weedy species and investigates the relationship between reproductive success and population size. In this species, there is no evidence of an Allee effect and reproductive success is not correlated with population size. In addition G. physocarpus is not capable of self-pollination, suggesting it is completely reliant on pollinators for seed set. The lack of a relationship between pollination success and population size is therefore likely explained by the generalized wasp pollination system of this species. Several milkweeds are invasive outside of their native ranges. Invasive species either need to co-opt native pollinators in order to reproduce or reduce their reliance on pollinators through having the ability to self-pollinate. Co-opting native pollinators is expected to be easier in species that have generalized pollination systems, alternatively species with specialized flower morphologies need to rely on similar functional groups of pollinators to be present within the invaded range. Chapter two investigates the pollination biology and pollination success of the invasive milkweed, Araujia sericifera, and finds that in South Africa, this species is visited mainly by native honeybees and nocturnal moths. Moths however contribute little to pollen removal, and deposition. Based on the apparent morphological mismatch between the flower of A. sericifera and native honeybees, I propose that the native pollinators of this species are likely to be larger Hymenoptera (e.g. Bumblebees). Data from a breeding system study, indicated that this species is not capable of automatic self-pollination, but could set fruit from geitonogamous self-pollinations pointing to the importance of native pollinators for successful reproduction. The pollinaria of milkweeds can accumulate on pollinators to form pollen masses large enough to physically interfere with the foraging behaviour of pollinating insects. In chapter three I describe the pollination biology of Cynanchum ellipticum and find that this species is mainly pollinated by honeybees although this species is visited by several other members of Hymenoptera, Lepidoptera and Diptera. Due to the structure of the pollinaria, these chain together relatively efficiently and frequently form large pollinarium loads on the mouthparts of honeybees. However there is little evidence that these pollinarium loads influence the foraging times of pollinators and only a few individual honeybees exhibited longer foraging times and most honeybees were unaffected by the presence of large pollinarium loads. Within the genus Cynanchum there is large variation in the gynostegium structure that may influence the pattern of pollinarium loading on pollinators as well as pollen reception as shown in chapter three. In Chapter four, the pollination biology of Cynanchum obtusifolium is examined, and like that of C. ellipticum, this species is visited by a wide diversity of pollinators but honeybees appear to be the primary pollinators. More importantly this species is shown to be andromonoecious and produces two morphologically different flower types, that may be distinguished based on differences in the gynostegium structure. These two types of flower could mainly be distinguished by the length of the anther wings. I found that flowers with short anther wings function as male flowers by only exporting- and rarely receiving pollinia. Flowers with longer anther wings function as hermaphrodite flowers and can both export and receive pollinia. The ratio of male to hermaphrodite flowers varied at different times during the flowering season, but preliminary data suggested that this was not related to levels of pollination success. The genera Stapelia and Ceropegia are well known for their intricate floral adaptations that mimic the brood and feeding substrates of pollinating flies. Despite several studies that have documented the various adaptations to fly pollination in different species, there is a lack of natural history studies documenting different flower visitors, pollen loads and long term levels of pollination success in these species. In Chapter six I document the pollination biology of Ceropegia ampliata by documenting different pollinators and quantifying average levels of pollination success and the nectar reward. I also experimentally manipulated the trapping hairs of this species to determine whether trapping hairs influence average levels of pollen export and receipt. I show that Ceropegia ampliata is pollinated by a generalist guild of flies (mainly Tachinidae, Sarcophagidae, Muscidae and Lauxaniidae) and produces minute quantities of relatively dilute nectar as a reward. Pollination success was generally low in this species and increases periodically suggesting that the abundance of pollinators is patchy. I found that flowers with trapping hairs that had already wilted had higher levels of pollinarium removal than flowers with erect hairs, however experimentally removing the hairs had no significant effect on pollen export and receipt. In Chapter seven, I document the pollinators, pollen loads and long term levels of pollination success in Stapelia hirsuta var. bayllissi, a rare sapromyiophilous stapeliad. I find that, in contrast to C. ampliata, this species was specialized to pollination by small flies of the family Anthomyiidae. Similar to the results from Chapter seven, I find that long term levels of pollination success were typically low but could increase periodically, although such increases were generally unpredictable. There are currently very few records documenting pollinator interactions in the Periplocoideae. Many species within this subfamily exhibit open-access flowers suggestive of pollination by short-tongued insects. I investigated the pollination biology of Chlorocyathus lobulata, a rare species with a highly localized distribution. I aimed to determine the pollinators, average levels of pollination success and demography of this species in order to determine whether this rare species is suffering from the collapse of a highly specialized pollinator mutualism. I also quantified the high incidence of flower herbivory caused by larvae of the moth, Bocchoris onychinalis. I find that C. lobulata has a highly generalized fly pollination system and average levels of pollination success suggested that a large proportion of flowers had pollen removed and deposited suggesting that this species is not experiencing pollination failure. The large numbers of juveniles present also indicated that recruitment is taking place.
- Full Text:
- Date Issued: 2010
- Authors: Coombs, Gareth
- Date: 2010
- Subjects: Milkweeds -- South Africa Milkweeds -- South Africa -- Ecology Milkweeds -- South Africa -- Pollination Allee effect Self-pollination Pollination by insects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4189 , http://hdl.handle.net/10962/d1003758
- Description: Like orchids, the complexity of flowers found in asclepiads (Asclepiadoideae, Apocynaceae) and the fact that pollen is presented as pollinaria, offers excellent opportunities to study various aspects of plant-pollinator interactions. In this thesis I investigated two broad themes: ecological aspects of the pollination biology of hymenopteran and fly-pollinated asclepiads as well as the degree of specialization to certain pollinators in these species. Colonizing plants often reproduce through self-pollination, or have highly generalized pollination systems, or both. These characteristics facilitate establishment in small founding populations and generates the prediction that reproductive success should be independent of population size in these species. Chapter one examines the pollination biology of Gomphocarpus physocarpus, an indigenous, weedy species and investigates the relationship between reproductive success and population size. In this species, there is no evidence of an Allee effect and reproductive success is not correlated with population size. In addition G. physocarpus is not capable of self-pollination, suggesting it is completely reliant on pollinators for seed set. The lack of a relationship between pollination success and population size is therefore likely explained by the generalized wasp pollination system of this species. Several milkweeds are invasive outside of their native ranges. Invasive species either need to co-opt native pollinators in order to reproduce or reduce their reliance on pollinators through having the ability to self-pollinate. Co-opting native pollinators is expected to be easier in species that have generalized pollination systems, alternatively species with specialized flower morphologies need to rely on similar functional groups of pollinators to be present within the invaded range. Chapter two investigates the pollination biology and pollination success of the invasive milkweed, Araujia sericifera, and finds that in South Africa, this species is visited mainly by native honeybees and nocturnal moths. Moths however contribute little to pollen removal, and deposition. Based on the apparent morphological mismatch between the flower of A. sericifera and native honeybees, I propose that the native pollinators of this species are likely to be larger Hymenoptera (e.g. Bumblebees). Data from a breeding system study, indicated that this species is not capable of automatic self-pollination, but could set fruit from geitonogamous self-pollinations pointing to the importance of native pollinators for successful reproduction. The pollinaria of milkweeds can accumulate on pollinators to form pollen masses large enough to physically interfere with the foraging behaviour of pollinating insects. In chapter three I describe the pollination biology of Cynanchum ellipticum and find that this species is mainly pollinated by honeybees although this species is visited by several other members of Hymenoptera, Lepidoptera and Diptera. Due to the structure of the pollinaria, these chain together relatively efficiently and frequently form large pollinarium loads on the mouthparts of honeybees. However there is little evidence that these pollinarium loads influence the foraging times of pollinators and only a few individual honeybees exhibited longer foraging times and most honeybees were unaffected by the presence of large pollinarium loads. Within the genus Cynanchum there is large variation in the gynostegium structure that may influence the pattern of pollinarium loading on pollinators as well as pollen reception as shown in chapter three. In Chapter four, the pollination biology of Cynanchum obtusifolium is examined, and like that of C. ellipticum, this species is visited by a wide diversity of pollinators but honeybees appear to be the primary pollinators. More importantly this species is shown to be andromonoecious and produces two morphologically different flower types, that may be distinguished based on differences in the gynostegium structure. These two types of flower could mainly be distinguished by the length of the anther wings. I found that flowers with short anther wings function as male flowers by only exporting- and rarely receiving pollinia. Flowers with longer anther wings function as hermaphrodite flowers and can both export and receive pollinia. The ratio of male to hermaphrodite flowers varied at different times during the flowering season, but preliminary data suggested that this was not related to levels of pollination success. The genera Stapelia and Ceropegia are well known for their intricate floral adaptations that mimic the brood and feeding substrates of pollinating flies. Despite several studies that have documented the various adaptations to fly pollination in different species, there is a lack of natural history studies documenting different flower visitors, pollen loads and long term levels of pollination success in these species. In Chapter six I document the pollination biology of Ceropegia ampliata by documenting different pollinators and quantifying average levels of pollination success and the nectar reward. I also experimentally manipulated the trapping hairs of this species to determine whether trapping hairs influence average levels of pollen export and receipt. I show that Ceropegia ampliata is pollinated by a generalist guild of flies (mainly Tachinidae, Sarcophagidae, Muscidae and Lauxaniidae) and produces minute quantities of relatively dilute nectar as a reward. Pollination success was generally low in this species and increases periodically suggesting that the abundance of pollinators is patchy. I found that flowers with trapping hairs that had already wilted had higher levels of pollinarium removal than flowers with erect hairs, however experimentally removing the hairs had no significant effect on pollen export and receipt. In Chapter seven, I document the pollinators, pollen loads and long term levels of pollination success in Stapelia hirsuta var. bayllissi, a rare sapromyiophilous stapeliad. I find that, in contrast to C. ampliata, this species was specialized to pollination by small flies of the family Anthomyiidae. Similar to the results from Chapter seven, I find that long term levels of pollination success were typically low but could increase periodically, although such increases were generally unpredictable. There are currently very few records documenting pollinator interactions in the Periplocoideae. Many species within this subfamily exhibit open-access flowers suggestive of pollination by short-tongued insects. I investigated the pollination biology of Chlorocyathus lobulata, a rare species with a highly localized distribution. I aimed to determine the pollinators, average levels of pollination success and demography of this species in order to determine whether this rare species is suffering from the collapse of a highly specialized pollinator mutualism. I also quantified the high incidence of flower herbivory caused by larvae of the moth, Bocchoris onychinalis. I find that C. lobulata has a highly generalized fly pollination system and average levels of pollination success suggested that a large proportion of flowers had pollen removed and deposited suggesting that this species is not experiencing pollination failure. The large numbers of juveniles present also indicated that recruitment is taking place.
- Full Text:
- Date Issued: 2010
Multilingualism and ICT education at Rhodes University: an exploratory study
- Authors: Dalvit, Lorenzo
- Date: 2010
- Subjects: Educational technology -- South Africa Educational equalization -- South Africa Digital divide -- South Africa Information technology -- Social aspects -- South Africa Educational innovations Information technology -- Study and teaching Language and education -- South Africa Native language and education -- South Africa Rhodes University -- Students -- Attitudes Computer science -- Study and teaching (Higher)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1673 , http://hdl.handle.net/10962/d1003556
- Description: In South Africa, the linguistic hegemony of English over the African languages in the academic field reproduces unequal power relationships between their speakers. The present study shows that an intervention shaped by a counterhegemonic ideology can change the attitudes of Black university students, key players in spearheading social change. Usign statistical analysis and survey methodologies, this research explored the hegemonic role of English as the only language of learning and teaching (LoLT) in the discipline of Computer Science (CS) at Rhodes University. The study found that those speakers of an African language who are the most disadvantaged by the use of English as LoLT are also the most likely to resist a more extensive use of their mother tongue as an alternative. A group of such students were involved in the development and use of an online glossary of CS terms translated, explained and exemplified in an African language (isiXhosa). This experience increased the support for the use of African languages as additional LoLT, even in the Englishdominated field of study of Computer Science. This is an initial step towards promoting linguistic equality between English and African languages and social equality between their speakers.
- Full Text:
- Date Issued: 2010
- Authors: Dalvit, Lorenzo
- Date: 2010
- Subjects: Educational technology -- South Africa Educational equalization -- South Africa Digital divide -- South Africa Information technology -- Social aspects -- South Africa Educational innovations Information technology -- Study and teaching Language and education -- South Africa Native language and education -- South Africa Rhodes University -- Students -- Attitudes Computer science -- Study and teaching (Higher)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1673 , http://hdl.handle.net/10962/d1003556
- Description: In South Africa, the linguistic hegemony of English over the African languages in the academic field reproduces unequal power relationships between their speakers. The present study shows that an intervention shaped by a counterhegemonic ideology can change the attitudes of Black university students, key players in spearheading social change. Usign statistical analysis and survey methodologies, this research explored the hegemonic role of English as the only language of learning and teaching (LoLT) in the discipline of Computer Science (CS) at Rhodes University. The study found that those speakers of an African language who are the most disadvantaged by the use of English as LoLT are also the most likely to resist a more extensive use of their mother tongue as an alternative. A group of such students were involved in the development and use of an online glossary of CS terms translated, explained and exemplified in an African language (isiXhosa). This experience increased the support for the use of African languages as additional LoLT, even in the Englishdominated field of study of Computer Science. This is an initial step towards promoting linguistic equality between English and African languages and social equality between their speakers.
- Full Text:
- Date Issued: 2010
Photoluminescence study of ZnO doped with nitrogen and arsenic
- Authors: Dangbegnon, Julien Kouadio
- Date: 2010
- Subjects: Photoluminescence , Zinc oxide , Nitrogen , Arsenic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10518 , http://hdl.handle.net/10948/1216 , Photoluminescence , Zinc oxide , Nitrogen , Arsenic
- Description: In this work, the optical properties of ZnO doped with arsenic and nitrogen were studied. The ZnO samples were grown by Metalorganic Chemical Vapor Deposition (MOCVD). The solubility of nitrogen in the ZnO films, as well as its activation upon annealing, was also investigated. Hydrogen is known as a major source for passivation of the acceptors in ZnO:N. Therefore, it is crucial to dissociate the complex(es) formed by nitrogen and hydrogen and diffuse out the hydrogen in order to prevent the reformation of such complexes. High temperatures (≥ 600 C) are required for these purposes. In order to effectively remove the hydrogen impurities from the sample, it is important to know the optical fingerprints of hydrogen and its thermal stability. Therefore, the effects of annealing and hydrogen plasma treatment on bulk ZnO (hydrothermally grown) were first studied. The use of bulk material for this purpose was motivated by the well-resolved photoluminescence (PL) lines observed for bulk ZnO, which allow the identification of the different lines related to hydrogen after plasma treatment. Annealing at 850 C was effective for the removal of most of the hydrogen related transitions in the near-band-edge emission. Also, additional transitions at ~3.364 eV and ~3.361 eV were observed after hydrogen plasma treatment, which were ascribed to hydrogen-Zn vacancy complexes. In this work, a comparative study of the annealing ambient and temperature on ZnO films grown on GaAs substrate, using diethyl zinc (DEZn) and tertiary butanol (TBOH), showed that arsenic diffuses in the ZnO films and gives a shallow level in the band gap, which is involved in an acceptor-bound exciton line at 3.35 eV. This shallow level is visible when annealing is performed in oxygen, but not when annealing is performed in nitrogen, and indeed only for annealing temperatures around 550 C. However, annealing in either ambient also causes zinc to diffuse from the ZnO films into the GaAs substrate, rendering the electrical properties deduced from Hall measurements ambiguous. For ZnO:N, NO was used as both oxygen and nitrogen sources. Monitoring the concentration of nitrogen, carbon and hydrogen in the ZnO films, the formation of different complexes from these impurities were deduced. Furthermore, an investigation of the effect of annealing on the concentrations of impurities showed that their out- diffusion was strongly dependent on the crystalline quality of the ZnO films. For porous ZnO films, obtained at low growth temperatures (≤310 C), the out-diffusion of impurities was efficient, whereas for films grown at higher temperatures, which have improved crystalline quality, the out-diffusion was practically nonexistent. The out-diffusion of unwanted impurities may activate the nitrogen dopant in the ZnO films, as was confirmed by the PL measurements on the different samples grown at different temperatures. PL transitions at ~3.24 eV and ~3.17 eV were related to substitutional NO. These transitions were more dominant in the spectra of samples grown at low temperatures. An additional transition at ~3.1 eV was assigned to a donor-acceptor pair transition involving VZn, instead of NO, as previously reported.
- Full Text:
- Date Issued: 2010
- Authors: Dangbegnon, Julien Kouadio
- Date: 2010
- Subjects: Photoluminescence , Zinc oxide , Nitrogen , Arsenic
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10518 , http://hdl.handle.net/10948/1216 , Photoluminescence , Zinc oxide , Nitrogen , Arsenic
- Description: In this work, the optical properties of ZnO doped with arsenic and nitrogen were studied. The ZnO samples were grown by Metalorganic Chemical Vapor Deposition (MOCVD). The solubility of nitrogen in the ZnO films, as well as its activation upon annealing, was also investigated. Hydrogen is known as a major source for passivation of the acceptors in ZnO:N. Therefore, it is crucial to dissociate the complex(es) formed by nitrogen and hydrogen and diffuse out the hydrogen in order to prevent the reformation of such complexes. High temperatures (≥ 600 C) are required for these purposes. In order to effectively remove the hydrogen impurities from the sample, it is important to know the optical fingerprints of hydrogen and its thermal stability. Therefore, the effects of annealing and hydrogen plasma treatment on bulk ZnO (hydrothermally grown) were first studied. The use of bulk material for this purpose was motivated by the well-resolved photoluminescence (PL) lines observed for bulk ZnO, which allow the identification of the different lines related to hydrogen after plasma treatment. Annealing at 850 C was effective for the removal of most of the hydrogen related transitions in the near-band-edge emission. Also, additional transitions at ~3.364 eV and ~3.361 eV were observed after hydrogen plasma treatment, which were ascribed to hydrogen-Zn vacancy complexes. In this work, a comparative study of the annealing ambient and temperature on ZnO films grown on GaAs substrate, using diethyl zinc (DEZn) and tertiary butanol (TBOH), showed that arsenic diffuses in the ZnO films and gives a shallow level in the band gap, which is involved in an acceptor-bound exciton line at 3.35 eV. This shallow level is visible when annealing is performed in oxygen, but not when annealing is performed in nitrogen, and indeed only for annealing temperatures around 550 C. However, annealing in either ambient also causes zinc to diffuse from the ZnO films into the GaAs substrate, rendering the electrical properties deduced from Hall measurements ambiguous. For ZnO:N, NO was used as both oxygen and nitrogen sources. Monitoring the concentration of nitrogen, carbon and hydrogen in the ZnO films, the formation of different complexes from these impurities were deduced. Furthermore, an investigation of the effect of annealing on the concentrations of impurities showed that their out- diffusion was strongly dependent on the crystalline quality of the ZnO films. For porous ZnO films, obtained at low growth temperatures (≤310 C), the out-diffusion of impurities was efficient, whereas for films grown at higher temperatures, which have improved crystalline quality, the out-diffusion was practically nonexistent. The out-diffusion of unwanted impurities may activate the nitrogen dopant in the ZnO films, as was confirmed by the PL measurements on the different samples grown at different temperatures. PL transitions at ~3.24 eV and ~3.17 eV were related to substitutional NO. These transitions were more dominant in the spectra of samples grown at low temperatures. An additional transition at ~3.1 eV was assigned to a donor-acceptor pair transition involving VZn, instead of NO, as previously reported.
- Full Text:
- Date Issued: 2010
Molecular and cellular analysis of the interaction between soluble CD23 and CD11/CD18 integrins
- Authors: Daniels, Brodie Belinda
- Date: 2010
- Subjects: CD23 antigen , Immune response -- Regulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10303 , http://hdl.handle.net/10948/1217 , CD23 antigen , Immune response -- Regulation
- Description: The low affinity IgE receptor, CD23, is expressed by a wide variety of cells and cleaved from its original 45 kDa size to several smaller soluble CD23 proteins. Soluble CD23 function depends on the form of the protein and its interaction with various ligands. CD23 is believed to play an important role in regulating allergic responses and in inflammation, amongst others. β2 integrins are important in a variety of cell-adhesion reactions during immune-inflammatory mechanisms and the binding of their natural ligands generates outside-in cellular signalling, leading to cell activation. Although the binding of CD23 to β2 integrins contributes to this signalling in monocytes, the interaction site for CD23 is unknown. This study focused on the interaction of three soluble CD23 proteins with the β2 integrins CD11b/CD18 and CD11c/CD18. Differentiated HL60, THP1 and U937 monocytic cells were used to demonstrate the binding of three recombinant CD23 constructs (corresponding to 16, 25 and 33 kDa human soluble CD23) to upregulated CD11b/CD18 and CD11c/CD18. This binding was partially blocked by an antibody specific for the CD11b/CD18 αI domain, demonstrating that αI domains are involved in binding to CD23. Recombinant αI domain proteins of CD11b and CD11c were demonstrated to bind CD23 using ELISA and in surface plasmon resonance spectroscopy. The dissociation constants for CD23-CD11b/CD18 and CD23-CD11c/CD18 are comparable to other integrin ligands. This study has shown that CD23 interacts directly with the αI domains of β2 integrins and that the interaction surface likely spans the lectin domain as well as either the stalk and/or C-terminal tail of CD23. This study also looked at the effect that soluble CD23 proteins had on monocyte biology. It appears that iv sCD23 proteins have little effect on the phagocytic or chemotactic ability of monocytes, while an increase in oxidative burst was shown with the 16 kDa and 25 kDa CD23 proteins. Signalling pathways for the production of reactive oxygen species were investigated and it appears that the CD23 proteins signal mainly through the phosphoinositide-3 kinase pathway, although the mitogen activated protein kinase and Src kinase pathways may also play a role. These data suggest that sCD23 proteins induce outside-in signalling of β2 integrins and are able to change the activation state of CD11b/CD11c by stimulating oxidative burst. This needs to be further investigated by determining how the three sCD23 proteins are binding the CD11 proteins and investigating further leukocyte function and inflammatory responses by the cells.
- Full Text:
- Date Issued: 2010
- Authors: Daniels, Brodie Belinda
- Date: 2010
- Subjects: CD23 antigen , Immune response -- Regulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10303 , http://hdl.handle.net/10948/1217 , CD23 antigen , Immune response -- Regulation
- Description: The low affinity IgE receptor, CD23, is expressed by a wide variety of cells and cleaved from its original 45 kDa size to several smaller soluble CD23 proteins. Soluble CD23 function depends on the form of the protein and its interaction with various ligands. CD23 is believed to play an important role in regulating allergic responses and in inflammation, amongst others. β2 integrins are important in a variety of cell-adhesion reactions during immune-inflammatory mechanisms and the binding of their natural ligands generates outside-in cellular signalling, leading to cell activation. Although the binding of CD23 to β2 integrins contributes to this signalling in monocytes, the interaction site for CD23 is unknown. This study focused on the interaction of three soluble CD23 proteins with the β2 integrins CD11b/CD18 and CD11c/CD18. Differentiated HL60, THP1 and U937 monocytic cells were used to demonstrate the binding of three recombinant CD23 constructs (corresponding to 16, 25 and 33 kDa human soluble CD23) to upregulated CD11b/CD18 and CD11c/CD18. This binding was partially blocked by an antibody specific for the CD11b/CD18 αI domain, demonstrating that αI domains are involved in binding to CD23. Recombinant αI domain proteins of CD11b and CD11c were demonstrated to bind CD23 using ELISA and in surface plasmon resonance spectroscopy. The dissociation constants for CD23-CD11b/CD18 and CD23-CD11c/CD18 are comparable to other integrin ligands. This study has shown that CD23 interacts directly with the αI domains of β2 integrins and that the interaction surface likely spans the lectin domain as well as either the stalk and/or C-terminal tail of CD23. This study also looked at the effect that soluble CD23 proteins had on monocyte biology. It appears that iv sCD23 proteins have little effect on the phagocytic or chemotactic ability of monocytes, while an increase in oxidative burst was shown with the 16 kDa and 25 kDa CD23 proteins. Signalling pathways for the production of reactive oxygen species were investigated and it appears that the CD23 proteins signal mainly through the phosphoinositide-3 kinase pathway, although the mitogen activated protein kinase and Src kinase pathways may also play a role. These data suggest that sCD23 proteins induce outside-in signalling of β2 integrins and are able to change the activation state of CD11b/CD11c by stimulating oxidative burst. This needs to be further investigated by determining how the three sCD23 proteins are binding the CD11 proteins and investigating further leukocyte function and inflammatory responses by the cells.
- Full Text:
- Date Issued: 2010
Enhancing self-esteem as a teacher of English using action research
- Authors: Didloft, Virginia Charmaine
- Date: 2010
- Subjects: Self-esteem in children -- South Africa , Self-esteem -- Study and teaching , Self-perception in children -- South Africa , Social interaction in children -- South Africa , Educational psychology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9496 , http://hdl.handle.net/10948/1520 , Self-esteem in children -- South Africa , Self-esteem -- Study and teaching , Self-perception in children -- South Africa , Social interaction in children -- South Africa , Educational psychology -- South Africa
- Description: This thesis offers a critical reflection of a study I initiated to enhance self-esteem for self-actualization. The research process involved enhancing my own self-esteem before facilitating the enhancement of the self-esteem of my participants. This endeavour included the simultaneous exposure given to researcher and researched, with the aim of helping to attain the respective transformative potentials of the latter. An action research methodology was used, intending to improve my own practice and to involve and learn from the participants in order for all relevant stakeholders to capitalize from the learning experience. Whilst undertaking this study, I learned to reflect on my values, attitudes and relationships with my learners. I also became aware of how individuals‟ perceptions of themselves can influence other aspects of their development. This awareness enabled me to become more sensitive to the emotional needs of the learners in my care and also led to a greater understanding of their individuality. I came to comprehend the impact of a positive self-esteem on the learning process that aided me in developing an understanding of the positive impact an enhanced self-esteem has on how my learners view themselves. In the course of the research, I developed an awareness of the need to create a caring practice centred on values of gentleness, respect, kindness, awareness and recognition of individual strengths. These afore-mentioned values are premised on the recognition and acknowledgement of basic human rights, inclusivity, equality and social justice; principles reflecting my own living standards. This heightened vii awareness influenced the ways I organized the learning and teaching process in my classroom. Enhancing my own self-esteem and those of my learners basically involved interchangeable interventions such as encouraging involvement, allocating responsibilities, creating opportunities for assertiveness and being generous with affirmation, praise and motivation. These endeavours occurred within a social constructivist approach, enabling participants to construct their own epistemologies within their respective ontologies. My findings offer new conceptualizations about how an enhanced self-esteem can help individuals realize their fullest potential.
- Full Text:
- Date Issued: 2010
- Authors: Didloft, Virginia Charmaine
- Date: 2010
- Subjects: Self-esteem in children -- South Africa , Self-esteem -- Study and teaching , Self-perception in children -- South Africa , Social interaction in children -- South Africa , Educational psychology -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9496 , http://hdl.handle.net/10948/1520 , Self-esteem in children -- South Africa , Self-esteem -- Study and teaching , Self-perception in children -- South Africa , Social interaction in children -- South Africa , Educational psychology -- South Africa
- Description: This thesis offers a critical reflection of a study I initiated to enhance self-esteem for self-actualization. The research process involved enhancing my own self-esteem before facilitating the enhancement of the self-esteem of my participants. This endeavour included the simultaneous exposure given to researcher and researched, with the aim of helping to attain the respective transformative potentials of the latter. An action research methodology was used, intending to improve my own practice and to involve and learn from the participants in order for all relevant stakeholders to capitalize from the learning experience. Whilst undertaking this study, I learned to reflect on my values, attitudes and relationships with my learners. I also became aware of how individuals‟ perceptions of themselves can influence other aspects of their development. This awareness enabled me to become more sensitive to the emotional needs of the learners in my care and also led to a greater understanding of their individuality. I came to comprehend the impact of a positive self-esteem on the learning process that aided me in developing an understanding of the positive impact an enhanced self-esteem has on how my learners view themselves. In the course of the research, I developed an awareness of the need to create a caring practice centred on values of gentleness, respect, kindness, awareness and recognition of individual strengths. These afore-mentioned values are premised on the recognition and acknowledgement of basic human rights, inclusivity, equality and social justice; principles reflecting my own living standards. This heightened vii awareness influenced the ways I organized the learning and teaching process in my classroom. Enhancing my own self-esteem and those of my learners basically involved interchangeable interventions such as encouraging involvement, allocating responsibilities, creating opportunities for assertiveness and being generous with affirmation, praise and motivation. These endeavours occurred within a social constructivist approach, enabling participants to construct their own epistemologies within their respective ontologies. My findings offer new conceptualizations about how an enhanced self-esteem can help individuals realize their fullest potential.
- Full Text:
- Date Issued: 2010
The introduction of cyberhunts as a teaching and learning strategy to guide teachers towards the integration of computer technology in schools
- Authors: Du Plessis, André
- Date: 2010
- Subjects: Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9555 , http://hdl.handle.net/10948/1210 , Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Description: This study, which is based on a computer literacy teacher development programme that included introducing the teacher participants to the Internet, investigated whether the development of teacher ICT skills through the design of cyberhunts in a learning-as-design context, has the potential to promote the critical and developmental outcomes which form the basis of the South African National Curriculum Statement (NCS) and Draft White Paper on e-Education. The research was conducted within the post-positivist paradigm underpinned by a critical realist position and made use of qualitative and quantitative data1 gathering methods (mixed research) within an interpretative case study. Several different quantitative and qualitative data collection tools were used. Quantitative data gathering tools that had been used comprised of Likert scale questionnaires, a computer skills questionnaire, as well as certain sections within semi-closed-openended questionnaires. The qualitative data gathering tools that had been used were semi-closed-openended questionnaires, journal reflection sheets, observation and interviews. Ontologically the research was informed by a critical-realist perspective, epistemologically by a socio-cultural perspective; including situated learning within communities of practice; recognising the cognitive, social and situated learning dimension of teacher learning. Methodologically an interpretive case study approach was used, as the aim was to explore and investigate what the participants experienced, perceived and to understand the participants: what they felt, how they felt and why they felt and responded in certain ways. Initially the study focused on identifying how ready the participating schools and their participating teachers were in terms of the implementation and integration of Information and Communications Technology (ICT) with reference to first- and second order barriers. The findings suggest that addressing the first- and second order barriers is a vital aspect when assisting schools to move towards ICT integration. The next phase of the research focused on whether the cyberhunt design approach is capable of developing the critical outcomes of the NCS, whether it promotes motivation and interest, and whether it promotes collaboration. Both the quantitative and qualitative data portrayed positive results regarding the perceptions of the participating teachers in the cyberhunt design approach related to the critical and 1PLEASE NOTE: All the data referred to as in the appendix and all appendices are attached to this thesis on a CD containing the portable document format (PDF) files. This can be found at the back. iv developmental outcomes with reference to search and research, reading attitude, decision making, planning skills - which include time management and goal setting, knowledge and skills related to composing questions on different cognitive levels, computer skills, reflection and design skills. Positive results were also found related to audience, confidence, mental effort, motivation, interest and collaboration. The probabilities (p values) and practical statistical significance in the form of Cohen's d, were highly significant. The teachers’ final cyberhunt products suggest that the majority of the participants had obtained basic cyberhunt design skills. However, in spite of the positive results, it was found that not all teachers are yet ready to implement this approach exactly as it is intended. When interpreted within an activity theory perspective; the positive results might be attributed to the unmediated functioning of the rules, division of labour and community aspects of the theory, while the conditions required by complexity theory for the development of a complex learning community appear to have been met by the implementation of cyberhunts as a strategy. The conditions for enabling the development of a complex learning community; namely internal diversity, redundancy, decentralised control, organised randomness and neighbour interaction; also appear to have interacted with the unmediated aspects of activity theory in developing consensual rules and through the negotiation of the division of labour located within the community. In a like manner, positive results related to search and research, decision making, questioning, computer skills, reflection, design skills and audience reported can most likely be attributed to the functioning of the mediational tools as described by activity theory such as the computer technology, the Internet, the software that had been used and language. The data thus suggest that the interaction between both the unmediated elements and higher order mediated elements of activity theory, have most likely been the defining factors which created high levels of motivation, interest, collaboration and a positive classroom culture through which the critical and developmental outcomes of the South Africa curriculum can possibly be achieved within a complex learning community. The study also investigated how the teacher development process regarding ICT implementation should be managed. This study found that the acronym CRAR3FS2 holds the key to teacher development and classroom implementation. This acronym represents the verbs or actions that the participating teachers highly valued during implementation and what they have indicated as being important, namely: Care, Relate, Assess, Reflect, Read, Re-Plan, Feedback, Share and Support.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis, André
- Date: 2010
- Subjects: Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9555 , http://hdl.handle.net/10948/1210 , Educational technology , Computers -- Study and teaching , Computer-assisted instruction , Competency-based education
- Description: This study, which is based on a computer literacy teacher development programme that included introducing the teacher participants to the Internet, investigated whether the development of teacher ICT skills through the design of cyberhunts in a learning-as-design context, has the potential to promote the critical and developmental outcomes which form the basis of the South African National Curriculum Statement (NCS) and Draft White Paper on e-Education. The research was conducted within the post-positivist paradigm underpinned by a critical realist position and made use of qualitative and quantitative data1 gathering methods (mixed research) within an interpretative case study. Several different quantitative and qualitative data collection tools were used. Quantitative data gathering tools that had been used comprised of Likert scale questionnaires, a computer skills questionnaire, as well as certain sections within semi-closed-openended questionnaires. The qualitative data gathering tools that had been used were semi-closed-openended questionnaires, journal reflection sheets, observation and interviews. Ontologically the research was informed by a critical-realist perspective, epistemologically by a socio-cultural perspective; including situated learning within communities of practice; recognising the cognitive, social and situated learning dimension of teacher learning. Methodologically an interpretive case study approach was used, as the aim was to explore and investigate what the participants experienced, perceived and to understand the participants: what they felt, how they felt and why they felt and responded in certain ways. Initially the study focused on identifying how ready the participating schools and their participating teachers were in terms of the implementation and integration of Information and Communications Technology (ICT) with reference to first- and second order barriers. The findings suggest that addressing the first- and second order barriers is a vital aspect when assisting schools to move towards ICT integration. The next phase of the research focused on whether the cyberhunt design approach is capable of developing the critical outcomes of the NCS, whether it promotes motivation and interest, and whether it promotes collaboration. Both the quantitative and qualitative data portrayed positive results regarding the perceptions of the participating teachers in the cyberhunt design approach related to the critical and 1PLEASE NOTE: All the data referred to as in the appendix and all appendices are attached to this thesis on a CD containing the portable document format (PDF) files. This can be found at the back. iv developmental outcomes with reference to search and research, reading attitude, decision making, planning skills - which include time management and goal setting, knowledge and skills related to composing questions on different cognitive levels, computer skills, reflection and design skills. Positive results were also found related to audience, confidence, mental effort, motivation, interest and collaboration. The probabilities (p values) and practical statistical significance in the form of Cohen's d, were highly significant. The teachers’ final cyberhunt products suggest that the majority of the participants had obtained basic cyberhunt design skills. However, in spite of the positive results, it was found that not all teachers are yet ready to implement this approach exactly as it is intended. When interpreted within an activity theory perspective; the positive results might be attributed to the unmediated functioning of the rules, division of labour and community aspects of the theory, while the conditions required by complexity theory for the development of a complex learning community appear to have been met by the implementation of cyberhunts as a strategy. The conditions for enabling the development of a complex learning community; namely internal diversity, redundancy, decentralised control, organised randomness and neighbour interaction; also appear to have interacted with the unmediated aspects of activity theory in developing consensual rules and through the negotiation of the division of labour located within the community. In a like manner, positive results related to search and research, decision making, questioning, computer skills, reflection, design skills and audience reported can most likely be attributed to the functioning of the mediational tools as described by activity theory such as the computer technology, the Internet, the software that had been used and language. The data thus suggest that the interaction between both the unmediated elements and higher order mediated elements of activity theory, have most likely been the defining factors which created high levels of motivation, interest, collaboration and a positive classroom culture through which the critical and developmental outcomes of the South Africa curriculum can possibly be achieved within a complex learning community. The study also investigated how the teacher development process regarding ICT implementation should be managed. This study found that the acronym CRAR3FS2 holds the key to teacher development and classroom implementation. This acronym represents the verbs or actions that the participating teachers highly valued during implementation and what they have indicated as being important, namely: Care, Relate, Assess, Reflect, Read, Re-Plan, Feedback, Share and Support.
- Full Text:
- Date Issued: 2010
A combination of platinum anticancer drugs and mangiferin causes increased efficacy in cancer cell lines
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
Mobile phones interaction techniques for second economy people
- Authors: Edim, Azom Emmanuel
- Date: 2010
- Subjects: Rural development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Cell phone systems -- South Africa -- Eastern Cape , User interfaces (Computer systems) , Human-computer interaction , Community development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: vital:11392 , http://hdl.handle.net/10353/519 , Rural development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Cell phone systems -- South Africa -- Eastern Cape , User interfaces (Computer systems) , Human-computer interaction , Community development -- South Africa -- Eastern Cape
- Description: Second economy people in developing countries are people living in communities that are underserved in terms of basic amenities and social services. Due to literacy challenges and user accessibility problems in rural communities, it is often difficult to design user interfaces that conform to the capabilities and cultural experiences of low-literacy rural community users. Rural community users are technologically illiterate and lack the knowledge of the potential of information and communication technologies. In order to embrace new technology, users will need to perceive the user interface and application as useful and easy to interact with. This requires proper understanding of the users and their socio-cultural environment. This will enable the interfaces and interactions to conform to their behaviours, motivations as well as cultural experiences and preferences and thus enhance usability and user experience. Mobile phones have the potential to increase access to information and provide a platform for economic development in rural communities. Rural communities have economic potential in terms of agriculture and micro-enterprises. Information technology can be used to enhance socio-economic activities and improve rural livelihood. We conducted a study to design user interfaces for a mobile commerce application for micro-entrepreneurs in a rural community in South Africa. The aim of the study was to design mobile interfaces and interaction techniques that are easy to use and meet the cultural preferences and experiences of users who have little to no previous experience of mobile commerce technology. And also to explore the potentials of information technologies rural community users, and bring mobile added value services to rural micro-entrepreneurs. We applied a user-centred design approach in Dwesa community and used qualitative and quantitative research methods to collect data for the design of the user interfaces (graphic user interface and voice user interface) and mobile commerce application. We identified and used several interface elements to design and finally evaluate the graphical user interface. The statistics analysis of the evaluation results show that the users in the community have positive perception of the usefulness of the application, the ease of use and intention to use the application. Community users with no prior experience with this technology were able to learn and understand the interface, recorded minimum errors and a high level of v precision during task performance when they interacted with the shop-owner graphic user interface. The voice user interface designed in this study consists of two flavours (dual tone multi-frequency input and voice input) for rural users. The evaluation results show that community users recorded higher tasks successes and minimum errors with the dual tone multi-frequency input interface than the voice only input interface. Also, a higher percentage of users prefer the dual tone multi-frequency input interface. The t-Test statistical analysis performed on the tasks completion times and error rate show that there was significant statistical difference between the dual tone multi-frequency input interface and the voice input interface. The interfaces were easy to learn, understand and use. Properly designed user interfaces that meet the experience and capabilities of low-literacy users in rural areas will improve usability and users‟ experiences. Adaptation of interfaces to users‟ culture and preferences will enhance information services accessibility among different user groups in different regions. This will promote technology acceptance in rural communities for socio-economic benefits. The user interfaces presented in this study can be adapted to different cultures to provide similar services for marginalised communities in developing countries
- Full Text:
- Date Issued: 2010
- Authors: Edim, Azom Emmanuel
- Date: 2010
- Subjects: Rural development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Cell phone systems -- South Africa -- Eastern Cape , User interfaces (Computer systems) , Human-computer interaction , Community development -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Computer Science)
- Identifier: vital:11392 , http://hdl.handle.net/10353/519 , Rural development projects -- South Africa -- Eastern Cape , Poverty -- South Africa -- Eastern Cape , Cell phone systems -- South Africa -- Eastern Cape , User interfaces (Computer systems) , Human-computer interaction , Community development -- South Africa -- Eastern Cape
- Description: Second economy people in developing countries are people living in communities that are underserved in terms of basic amenities and social services. Due to literacy challenges and user accessibility problems in rural communities, it is often difficult to design user interfaces that conform to the capabilities and cultural experiences of low-literacy rural community users. Rural community users are technologically illiterate and lack the knowledge of the potential of information and communication technologies. In order to embrace new technology, users will need to perceive the user interface and application as useful and easy to interact with. This requires proper understanding of the users and their socio-cultural environment. This will enable the interfaces and interactions to conform to their behaviours, motivations as well as cultural experiences and preferences and thus enhance usability and user experience. Mobile phones have the potential to increase access to information and provide a platform for economic development in rural communities. Rural communities have economic potential in terms of agriculture and micro-enterprises. Information technology can be used to enhance socio-economic activities and improve rural livelihood. We conducted a study to design user interfaces for a mobile commerce application for micro-entrepreneurs in a rural community in South Africa. The aim of the study was to design mobile interfaces and interaction techniques that are easy to use and meet the cultural preferences and experiences of users who have little to no previous experience of mobile commerce technology. And also to explore the potentials of information technologies rural community users, and bring mobile added value services to rural micro-entrepreneurs. We applied a user-centred design approach in Dwesa community and used qualitative and quantitative research methods to collect data for the design of the user interfaces (graphic user interface and voice user interface) and mobile commerce application. We identified and used several interface elements to design and finally evaluate the graphical user interface. The statistics analysis of the evaluation results show that the users in the community have positive perception of the usefulness of the application, the ease of use and intention to use the application. Community users with no prior experience with this technology were able to learn and understand the interface, recorded minimum errors and a high level of v precision during task performance when they interacted with the shop-owner graphic user interface. The voice user interface designed in this study consists of two flavours (dual tone multi-frequency input and voice input) for rural users. The evaluation results show that community users recorded higher tasks successes and minimum errors with the dual tone multi-frequency input interface than the voice only input interface. Also, a higher percentage of users prefer the dual tone multi-frequency input interface. The t-Test statistical analysis performed on the tasks completion times and error rate show that there was significant statistical difference between the dual tone multi-frequency input interface and the voice input interface. The interfaces were easy to learn, understand and use. Properly designed user interfaces that meet the experience and capabilities of low-literacy users in rural areas will improve usability and users‟ experiences. Adaptation of interfaces to users‟ culture and preferences will enhance information services accessibility among different user groups in different regions. This will promote technology acceptance in rural communities for socio-economic benefits. The user interfaces presented in this study can be adapted to different cultures to provide similar services for marginalised communities in developing countries
- Full Text:
- Date Issued: 2010
Implementation of novel flow cytometric methods to assess the in vitro antidiabetic mechanism of a Sutherlandia Frutescens extract
- Authors: Elliot, Gayle Pamela
- Date: 2010
- Subjects: Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10304 , http://hdl.handle.net/10948/1439 , Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Description: The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole-body glucose homeostasis. Deregulation of insulin action manifests itself as insulin resistance, a key component of type 2 diabetes. Insulin resistance is also observed in HIV patients receiving protease inhibitors. An agent that can reversibly induce an insulin-resistant state would be a very useful tool in developing model systems that mimic the pathogenesis of type 2 diabetes. Insulin resistance can arise from defects in insulin signal transduction, changes in the expression of proteins or genes that are targets of insulin action, cross talk from other hormonal systems or metabolic abnormalities. Deterioration of the insulin-receptor-signalling pathway at different levels leading to decreased levels of signalling pathway intermediates and/or decreased activation through phosphorylation accounts for the evolution from an insulin-resistant state to type 2 diabetes. In addition, defects in GLUT4 glucose transporter translocation are observed, further fuelling impairments in skeletal muscle glucose uptake. Levels of insulin-induced GLUT4 translocation in the skeletal muscle of type 2 diabetic patients are typically reduced by 90%. Many cellular pathways & their intermediates are in some way or another linked to insulin signalling. This study focused on three of these namely the PI3-kinase/Akt pathway, the Mitogen Activated Protein Kinase (MAPK) cascade and the AMP Kinase pathway, with successful monitoring of the PI3-K pathway. Investigations involved observing and evaluating the effects of various compounds as well as an indigenous medicinal plant, Sutherlandia frutescens on the activities of key insulin signalling pathway intermediates within the three fore mentioned pathways including Akt, AMPK and MEK1/2 as well as membrane surface GLUT4 levels. Scientific research has in the past leant heavily on Western blotting as the method of choice for gaining vital information relating to signal transduction pathways, however for research into cellular mechanisms the negatives of this method outweigh the positives. The drawbacks include a need for large amount of cells, multiple washing steps which may be disadvantageous to any weak and transient interactions as well as lysing of cells which may interfere with the maintenance of the subcellular localisation of a specific signalling event. Based on these, the need for a better method in terms of speed & reliability to monitor phosphorylation states of signal transduction pathway intermediates & GLUT4 translocation was evident and was one VII of the main aims & successes of this study. The method created used the mouse muscle cell line C2C12 in conjunction with the quick, sensitive method of flow cytometry which allowed us to monitor these processes in these cells through immune-labelling. Adherent cell cultures such as the C2C12 cell line pose the problem of possible damage to plasma membrane receptors (including insulin receptors) during harvesting to obtain a cell suspension for flow cytometry. We however used C2C12 mouse myocytes to optimize a method yielding insulin responsive cells in suspension that were successfully used for flow cytometry after immunelabelling of insulin signalling intermediates. Insulin (0.1μM) significantly raised the levels of both P-Akt and GLUT4 above basal levels. This effect was shown to be dose dependent. At a concentration of 50μg/ml, Sutherlandia frutescens was able to act as an insulin-mimetic in terms of its ability to increase P-Akt levels, GLUT4 translocation and glucose utilisation in an acute manner. These increases could be reduced with the addition of wortmannin, a PI3-K inhibitor. Therefore, these results suggest the mechanism of the plant extract’s insulin-like activity may be in part due to the activation of the insulin signalling pathway leading to GLUT4 translocation, which involves the phosphorylation of insulin receptor- and subsequent PI3-K activity, leading to P-Akt activity. These results provide further evidence of this plant extract’s anti-diabetic potential. The effect of Sutherlandia frutescens on insulin secretion, calcium signalling and proliferation in INS-1 rat pancreatic cells was also investigated and it was found to increase the activities of all of these processes. However no change in the levels of GLUT2 glucose transporter was seen. Ritonavir is prescribed by the South African Department of Health in co-formulation with other protease inhibitors within its second regime in the treatment of HIV and AIDS. Using C2C12 cells, ritonavir decreased glucose uptake acutely and had no effect on GLUT4 translocation however surprisingly increased P-Akt levels. In conclusion, it was found that Sutherlandia frutescens has antidiabetic benefits, diverse in nature depending on tissue type as well as length of time administered. The establishment of novel flow cytometry techniques to assess antidiabetic properties using in vitro cell culture was achieved. These methods will be useful in the future for the assessment of insulin sensitivity and in the identification of novel compounds that stimulate the insulin signalling pathways.
- Full Text:
- Date Issued: 2010
- Authors: Elliot, Gayle Pamela
- Date: 2010
- Subjects: Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10304 , http://hdl.handle.net/10948/1439 , Insulin resistance -- South Africa , Insulin -- Therapeutic use -- South Africa , Medicinal plants -- South Africa , Non-insulin-dependent diabetes -- South Africa
- Description: The ability of insulin to stimulate glucose uptake into muscle and adipose tissue is central to the maintenance of whole-body glucose homeostasis. Deregulation of insulin action manifests itself as insulin resistance, a key component of type 2 diabetes. Insulin resistance is also observed in HIV patients receiving protease inhibitors. An agent that can reversibly induce an insulin-resistant state would be a very useful tool in developing model systems that mimic the pathogenesis of type 2 diabetes. Insulin resistance can arise from defects in insulin signal transduction, changes in the expression of proteins or genes that are targets of insulin action, cross talk from other hormonal systems or metabolic abnormalities. Deterioration of the insulin-receptor-signalling pathway at different levels leading to decreased levels of signalling pathway intermediates and/or decreased activation through phosphorylation accounts for the evolution from an insulin-resistant state to type 2 diabetes. In addition, defects in GLUT4 glucose transporter translocation are observed, further fuelling impairments in skeletal muscle glucose uptake. Levels of insulin-induced GLUT4 translocation in the skeletal muscle of type 2 diabetic patients are typically reduced by 90%. Many cellular pathways & their intermediates are in some way or another linked to insulin signalling. This study focused on three of these namely the PI3-kinase/Akt pathway, the Mitogen Activated Protein Kinase (MAPK) cascade and the AMP Kinase pathway, with successful monitoring of the PI3-K pathway. Investigations involved observing and evaluating the effects of various compounds as well as an indigenous medicinal plant, Sutherlandia frutescens on the activities of key insulin signalling pathway intermediates within the three fore mentioned pathways including Akt, AMPK and MEK1/2 as well as membrane surface GLUT4 levels. Scientific research has in the past leant heavily on Western blotting as the method of choice for gaining vital information relating to signal transduction pathways, however for research into cellular mechanisms the negatives of this method outweigh the positives. The drawbacks include a need for large amount of cells, multiple washing steps which may be disadvantageous to any weak and transient interactions as well as lysing of cells which may interfere with the maintenance of the subcellular localisation of a specific signalling event. Based on these, the need for a better method in terms of speed & reliability to monitor phosphorylation states of signal transduction pathway intermediates & GLUT4 translocation was evident and was one VII of the main aims & successes of this study. The method created used the mouse muscle cell line C2C12 in conjunction with the quick, sensitive method of flow cytometry which allowed us to monitor these processes in these cells through immune-labelling. Adherent cell cultures such as the C2C12 cell line pose the problem of possible damage to plasma membrane receptors (including insulin receptors) during harvesting to obtain a cell suspension for flow cytometry. We however used C2C12 mouse myocytes to optimize a method yielding insulin responsive cells in suspension that were successfully used for flow cytometry after immunelabelling of insulin signalling intermediates. Insulin (0.1μM) significantly raised the levels of both P-Akt and GLUT4 above basal levels. This effect was shown to be dose dependent. At a concentration of 50μg/ml, Sutherlandia frutescens was able to act as an insulin-mimetic in terms of its ability to increase P-Akt levels, GLUT4 translocation and glucose utilisation in an acute manner. These increases could be reduced with the addition of wortmannin, a PI3-K inhibitor. Therefore, these results suggest the mechanism of the plant extract’s insulin-like activity may be in part due to the activation of the insulin signalling pathway leading to GLUT4 translocation, which involves the phosphorylation of insulin receptor- and subsequent PI3-K activity, leading to P-Akt activity. These results provide further evidence of this plant extract’s anti-diabetic potential. The effect of Sutherlandia frutescens on insulin secretion, calcium signalling and proliferation in INS-1 rat pancreatic cells was also investigated and it was found to increase the activities of all of these processes. However no change in the levels of GLUT2 glucose transporter was seen. Ritonavir is prescribed by the South African Department of Health in co-formulation with other protease inhibitors within its second regime in the treatment of HIV and AIDS. Using C2C12 cells, ritonavir decreased glucose uptake acutely and had no effect on GLUT4 translocation however surprisingly increased P-Akt levels. In conclusion, it was found that Sutherlandia frutescens has antidiabetic benefits, diverse in nature depending on tissue type as well as length of time administered. The establishment of novel flow cytometry techniques to assess antidiabetic properties using in vitro cell culture was achieved. These methods will be useful in the future for the assessment of insulin sensitivity and in the identification of novel compounds that stimulate the insulin signalling pathways.
- Full Text:
- Date Issued: 2010
Beta-N-methylamino-L-alanine in South African fresh water cyanobacteria : incidence, prevalence, ecotoxicological considerations and human exposure risk
- Authors: Esterhuizen-Londt, Maranda
- Date: 2010
- Subjects: Cyanobacteria , Bioaccumulation , Chromatographic analysis , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10306 , http://hdl.handle.net/10948/1473 , Cyanobacteria , Bioaccumulation , Chromatographic analysis , Neurotoxic agents
- Description: β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid associated with human neurodegenerative disease. Due to the cosmopolitan nature of cyanobacteria, detection of BMAA in cyanobacteria has caused concerns about human exposure risk. This study was therefore based on the hypothesis that BMAA poses a health risk to humans either by direct ingestion or by indirect exposure to BMAA from a cyanobacterial source via a freshwater food chain. A validated gas chromatography-mass spectrometry (GC-MS) BMAA analysis method and a confirmatory liquid chromatography-mass spectrometry (LC-MS) method, with improved sensitivity, were developed in addition to a LC-MS/MS method for analyte confirmation. These methods were used to quantify BMAA in South African cyanobacteria, isolated from various potable water reservoirs. The majority of the isolates tested, contained BMAA. Possible human exposure by direct consumption of BMAA released from cyanobacterial blooms was investigated by the development of a robust solid phase extraction (SPE) method used for BMAA concentration and quantification in raw and treated tap water. Despite the use of the SPE method that facilitated the concentration of BMAA from large quantities of water, no free dissolved BMAA was detected in raw or processed fresh water. The fate of exogenous BMAA was therefore investigated firstly by evaluating the efficacy of standard water treatment processes employed in South Africa and secondly by investigating the possibility of BMAA bioaccumulation and biomagnification in aquatic food chains. Standard water treatment processes proved highly efficient at removing free dissolved BMAA, explaining the absence of BMAA in treated tap water. However, the cause of the BMAA absence in raw potable water remained unknown. Uptake of BMAA by model aquatic organisms was investigated in controlled experiments. BMAA uptake was documented in both Ceratophyllum demersum and Daphnia magna, however, BMAA-protein association and biomagnification were not observed in D. magna. BMAA had an inhibitory effect on the oxidative stress enzyme acitivties of both organisms tested (as well as human S9 extracts), resulting in accumulation of detrimental reactive oxygen species (ROS) in the cells. Exposure of crop plants to BMAA in controlled experiments resulted in BMAA uptake, protein association, and subsequent inhibition of the antioxidative enzyme activities. However, BMAA was detected in neither free nor protein-associated form in natural crop plants irrigated with known BMAA-containing bloom water. Post-mortem liver samples of Clarias gariepinus (Catfish) and Crocodylus niloticus (Crocodile), from a natural fresh water ecosystem that experienced frequent cyanobacterial blooms, contained both free and protein-associated BMAA. Higher BMAA concentrations were found in crocodile liver samples compared to fish liver samples, strongly suggesting biomagnification from one trophic level to the next. BMAA concentrations corresponded to crocodile age. This is the first report of bioaccumulation and biomagnification in two trophic levels in a fresh water ecosystem. These findings strongly suggest possible human exposure via aquatic food chains of cyanobacterial origin. Direct BMAA exposure via drinking water is not plausible due to the efficiency of standard water treatment processes to remove BMAA. The use of raw water for agricultural and recreational use, however, remains a problem. The development of management strategies as well as daily tolerable levels for BMAA is urgently required.
- Full Text:
- Date Issued: 2010
- Authors: Esterhuizen-Londt, Maranda
- Date: 2010
- Subjects: Cyanobacteria , Bioaccumulation , Chromatographic analysis , Neurotoxic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10306 , http://hdl.handle.net/10948/1473 , Cyanobacteria , Bioaccumulation , Chromatographic analysis , Neurotoxic agents
- Description: β-N-methylamino-L-alanine (BMAA) is a non-proteinogenic amino acid associated with human neurodegenerative disease. Due to the cosmopolitan nature of cyanobacteria, detection of BMAA in cyanobacteria has caused concerns about human exposure risk. This study was therefore based on the hypothesis that BMAA poses a health risk to humans either by direct ingestion or by indirect exposure to BMAA from a cyanobacterial source via a freshwater food chain. A validated gas chromatography-mass spectrometry (GC-MS) BMAA analysis method and a confirmatory liquid chromatography-mass spectrometry (LC-MS) method, with improved sensitivity, were developed in addition to a LC-MS/MS method for analyte confirmation. These methods were used to quantify BMAA in South African cyanobacteria, isolated from various potable water reservoirs. The majority of the isolates tested, contained BMAA. Possible human exposure by direct consumption of BMAA released from cyanobacterial blooms was investigated by the development of a robust solid phase extraction (SPE) method used for BMAA concentration and quantification in raw and treated tap water. Despite the use of the SPE method that facilitated the concentration of BMAA from large quantities of water, no free dissolved BMAA was detected in raw or processed fresh water. The fate of exogenous BMAA was therefore investigated firstly by evaluating the efficacy of standard water treatment processes employed in South Africa and secondly by investigating the possibility of BMAA bioaccumulation and biomagnification in aquatic food chains. Standard water treatment processes proved highly efficient at removing free dissolved BMAA, explaining the absence of BMAA in treated tap water. However, the cause of the BMAA absence in raw potable water remained unknown. Uptake of BMAA by model aquatic organisms was investigated in controlled experiments. BMAA uptake was documented in both Ceratophyllum demersum and Daphnia magna, however, BMAA-protein association and biomagnification were not observed in D. magna. BMAA had an inhibitory effect on the oxidative stress enzyme acitivties of both organisms tested (as well as human S9 extracts), resulting in accumulation of detrimental reactive oxygen species (ROS) in the cells. Exposure of crop plants to BMAA in controlled experiments resulted in BMAA uptake, protein association, and subsequent inhibition of the antioxidative enzyme activities. However, BMAA was detected in neither free nor protein-associated form in natural crop plants irrigated with known BMAA-containing bloom water. Post-mortem liver samples of Clarias gariepinus (Catfish) and Crocodylus niloticus (Crocodile), from a natural fresh water ecosystem that experienced frequent cyanobacterial blooms, contained both free and protein-associated BMAA. Higher BMAA concentrations were found in crocodile liver samples compared to fish liver samples, strongly suggesting biomagnification from one trophic level to the next. BMAA concentrations corresponded to crocodile age. This is the first report of bioaccumulation and biomagnification in two trophic levels in a fresh water ecosystem. These findings strongly suggest possible human exposure via aquatic food chains of cyanobacterial origin. Direct BMAA exposure via drinking water is not plausible due to the efficiency of standard water treatment processes to remove BMAA. The use of raw water for agricultural and recreational use, however, remains a problem. The development of management strategies as well as daily tolerable levels for BMAA is urgently required.
- Full Text:
- Date Issued: 2010
Critical reflections on the war on terrorism from an international human rights perspective
- Fabbriciani, Antonio Antonino
- Authors: Fabbriciani, Antonio Antonino
- Date: 2010
- Subjects: Human rights , War on Terrorism, 2001-2009 , Civil rights , International law
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9041 , http://hdl.handle.net/10948/1205 , Human rights , War on Terrorism, 2001-2009 , Civil rights , International law
- Description: This study explored the balancing out of the rights associated with terrorist and counter-terrorist attacks by using descriptive case studies of the US 9/11 attacks; and the counter-terrorist attacks on Afghanistan and Iraq. The research was conducted within a critical theory paradigm, drawing on the ideas of Habermas and other Critical Theorists. The research design was influenced by the securitive and ideological nature of the topic and it was decided that an extensive review of literature would be more suitable than a field study. A small number of interviews added to the richness of the data. Human rights, needs and international relations were investigated to serve as a theoretical starting-point for the study (Chapter 2). The case studies were subsequently explored against the background of this theoretical approach. This thesis therefore assessed the impact of human rights law on terrorism and counter-terrorism attacks under the Human Rights Act (1998). It considered how the provisions of the Human Rights Act have influenced the formulation and interpretation of anti-terrorism laws, and it examined the role of the judiciary in adjudicating disputes between the individual and the state. It further discussed human needs and the progress on human rights, terrorist attacks, as well as counter-terrorism attacks. Extensive data was gathered on the 9/11 attacks, and it was concluded that these attacks fall within the definition of crimes against humanity under international human rights jurisprudence. To bring about a truly secure world we must adopt a new paradigm that shifts priority to the security of the individuals and of communities to achieving human security, the honouring of human rights, and respect for the rule of law. This will obviously require a renewed commitment by all individuals and a shared sense of responsibility for all people, all over the world. What we need now is a major course correction – a new iii A. Fabbriciani approach which begins with a broader understanding of what defines human rights and the rule of law (Wilson, 2007). The study also focuses on counter-terrorist attacks in Afghanistan and Iraq (Chapters 3 and 4). It was shown that counter-terrorist attacks had an effect on the global economic system and development policies, which have been dominated by ideological strategies for many years. However, resistance has come from Islamic states, which have realised that new-liberal economic practices are incompatible with their theological and economic traditions. This has caused a situation to rethink global development programmes by political leaders, and to move away from new-liberal schemes towards true global development strategies. One of the main findings of the study was that the crimes of persecution and torture on the basis of political or religious views have been perpetrated by both parties, namely Al-Qaeda, and the US and its allies. It has been shown that the explored acts of terrorism and counter-attacks represent crimes against humanity, as defined by the relevant provisions of international law.
- Full Text:
- Date Issued: 2010
- Authors: Fabbriciani, Antonio Antonino
- Date: 2010
- Subjects: Human rights , War on Terrorism, 2001-2009 , Civil rights , International law
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9041 , http://hdl.handle.net/10948/1205 , Human rights , War on Terrorism, 2001-2009 , Civil rights , International law
- Description: This study explored the balancing out of the rights associated with terrorist and counter-terrorist attacks by using descriptive case studies of the US 9/11 attacks; and the counter-terrorist attacks on Afghanistan and Iraq. The research was conducted within a critical theory paradigm, drawing on the ideas of Habermas and other Critical Theorists. The research design was influenced by the securitive and ideological nature of the topic and it was decided that an extensive review of literature would be more suitable than a field study. A small number of interviews added to the richness of the data. Human rights, needs and international relations were investigated to serve as a theoretical starting-point for the study (Chapter 2). The case studies were subsequently explored against the background of this theoretical approach. This thesis therefore assessed the impact of human rights law on terrorism and counter-terrorism attacks under the Human Rights Act (1998). It considered how the provisions of the Human Rights Act have influenced the formulation and interpretation of anti-terrorism laws, and it examined the role of the judiciary in adjudicating disputes between the individual and the state. It further discussed human needs and the progress on human rights, terrorist attacks, as well as counter-terrorism attacks. Extensive data was gathered on the 9/11 attacks, and it was concluded that these attacks fall within the definition of crimes against humanity under international human rights jurisprudence. To bring about a truly secure world we must adopt a new paradigm that shifts priority to the security of the individuals and of communities to achieving human security, the honouring of human rights, and respect for the rule of law. This will obviously require a renewed commitment by all individuals and a shared sense of responsibility for all people, all over the world. What we need now is a major course correction – a new iii A. Fabbriciani approach which begins with a broader understanding of what defines human rights and the rule of law (Wilson, 2007). The study also focuses on counter-terrorist attacks in Afghanistan and Iraq (Chapters 3 and 4). It was shown that counter-terrorist attacks had an effect on the global economic system and development policies, which have been dominated by ideological strategies for many years. However, resistance has come from Islamic states, which have realised that new-liberal economic practices are incompatible with their theological and economic traditions. This has caused a situation to rethink global development programmes by political leaders, and to move away from new-liberal schemes towards true global development strategies. One of the main findings of the study was that the crimes of persecution and torture on the basis of political or religious views have been perpetrated by both parties, namely Al-Qaeda, and the US and its allies. It has been shown that the explored acts of terrorism and counter-attacks represent crimes against humanity, as defined by the relevant provisions of international law.
- Full Text:
- Date Issued: 2010
Improving Productivity of Maize-based Smallholder Irrigated Cropping Systems: A Case Study of Zanyokwe Irrigation Scheme, Eastern Cape, South Africa
- Authors: Fanadzo, Morris
- Date: 2010
- Subjects: Farms, Small -- South Africa -- Eastern Cape Crop yields -- South Africa -- Eastern Cape Agricultural productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/11009 , vital:36450
- Description: Smallholder irrigation schemes (SIS) in South Africa have performed poorly and failed to achieve the development objectives of sustaining rural livelihoods by increasing crop production and income. Limited knowledge of crop production among farmers is one constraint to improved crop productivity and, yet little research has been carried out to relate agronomic practices to productivity. This study was aimed at identifying strategies to improve the productivity of maize-based smallholder irrigated cropping systems in South Africa, using Zanyokwe irrigation scheme (ZIS) in the Eastern Cape Province as a case study. The research design was emergent, developed progressively as influenced by the progressive analyses that were made. The research work involved two main phases: exploratory studies and refinement on-farm experiments for testing technologies as informed by the exploratory studies. Exploratory studies were aimed at describing farmer crop production practices in major crop enterprises and identifying and prioritizing major agronomic yield constraints. Findings indicated that the overall performance of the cropping systems was poor as evidenced by low overall yields of < 25% of the potential in maize and butternut. Poor management of weeds, soil fertility, plant populations and water, late planting and poor cultivar choice were the most important yield constraints. The average cropping intensity achieved by farmers was only 48%. New hybrids yielded 50 - 65% higher grain than the cultivars commonly grown by farmers. However, farmers favoured their traditional cultivars, as they preferred green maize production as opposed to dry grains. As a result of these findings, focused research was designed on options for iii improving green maize production, soil fertility, crop stand and weed management in crop production. On-farm trials were, therefore, designed to (1) compare the response to nitrogen (N) rate of direct seeded and transplanted maize; (2) evaluate comparative performance of direct seeded and transplanted green maize under farmer management, and to work out the economics of transplanting; (3) investigate the effects of row spacing and atrazine dosage on weed dynamics maize yield; (4) determine the effects of inter-row spacing and plant population on weed dynamics and maize yield; and (5) investigate the effects of pre-plant weed control, N rate and plant population on weed dynamics and butternut yield. Maize transplanting improved crop stand, had earlier maturity and yielded higher at lower N rates compared to direct seeding for both green and grain maize. Total costs that varied were higher by R3 565 ha-1 for transplanted maize compared to direct-seeded maize, but the net benefits from transplanting were also much higher by R8 773 ha-1. Farmers favoured transplanting, citing bigger cobs, early maturity and the absence of seedling damage by birds, when maize was transplanted. However, a follow-up survey conducted during the subsequent year indicated that five of the six farmers abandoned transplanting, citing shortage of labour and high cost of commercially produced seedlings. It was concluded that transplanting is unlikely to be adopted unless the labour intensiveness of manual transplanting can be solved. Increasing atrazine dosage from a third of the label recommended dosage (LRD) and reducing row spacing from 90 to 45 cm resulted in an increase in weed mortality. A 100% kill of annual broadleaf weeds was possible while iv perennial grasses and the annual broadleaf weed, Oxalis latifolia, could not be controlled even at the LRD. However, improved weed mortality with increase in atrazine dosage and/or narrow rows did not translate into improved maize productivity. In butternut, pre-plant weed control resulted in a six-fold decrease in weed biomass and a 100% increase in fruit yield. These findings demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on maize yields in smallholder farming systems. The results also suggested that pre-plant weed control is one of the pre-requisite to successful butternut production in SIS in South Africa. Increasing maize population from 40 000 to 60 000 plants ha-1 resulted in a 30% grain yield increase, but decreased length of cobs. Row spacing had no effect on maize yield at 40 000 plants ha-1, but at 60 000 plants ha-1 45 cm rows resulted in 11% higher grain yield (12 547 kg ha-1) than 90 cm rows (11 288 kg ha-1). Butternut yield increased significantly (p < 0.01) with increase in plant population and N rate. The optimum butternut population and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. Pre-plant weed control in butternut resulted in a six-fold decrease in weed biomass. Increasing butternut planting density from 10 000 to 30 000 plants ha-1 decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. This result suggest that application of non-selective herbicide before planting is one technique that can be used by farmers as part of integrated weed management to give the crop a competitive advantage in the early growth stages before the plants start to produce vines. Yield increased significantly (p < 0.01) with increase in plant density and N rate. The optimum plant density and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. These findings emphasise the need to take into consideration production practices by farmers as a basis to build up skills in the management of crop enterprises and the farm as a viable business in any efforts to improve on the performance of SIS in South Africa. Future research should concentrate on labour-saving sustainable production technologies for SIS in South Africa.
- Full Text:
- Date Issued: 2010
- Authors: Fanadzo, Morris
- Date: 2010
- Subjects: Farms, Small -- South Africa -- Eastern Cape Crop yields -- South Africa -- Eastern Cape Agricultural productivity -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/11009 , vital:36450
- Description: Smallholder irrigation schemes (SIS) in South Africa have performed poorly and failed to achieve the development objectives of sustaining rural livelihoods by increasing crop production and income. Limited knowledge of crop production among farmers is one constraint to improved crop productivity and, yet little research has been carried out to relate agronomic practices to productivity. This study was aimed at identifying strategies to improve the productivity of maize-based smallholder irrigated cropping systems in South Africa, using Zanyokwe irrigation scheme (ZIS) in the Eastern Cape Province as a case study. The research design was emergent, developed progressively as influenced by the progressive analyses that were made. The research work involved two main phases: exploratory studies and refinement on-farm experiments for testing technologies as informed by the exploratory studies. Exploratory studies were aimed at describing farmer crop production practices in major crop enterprises and identifying and prioritizing major agronomic yield constraints. Findings indicated that the overall performance of the cropping systems was poor as evidenced by low overall yields of < 25% of the potential in maize and butternut. Poor management of weeds, soil fertility, plant populations and water, late planting and poor cultivar choice were the most important yield constraints. The average cropping intensity achieved by farmers was only 48%. New hybrids yielded 50 - 65% higher grain than the cultivars commonly grown by farmers. However, farmers favoured their traditional cultivars, as they preferred green maize production as opposed to dry grains. As a result of these findings, focused research was designed on options for iii improving green maize production, soil fertility, crop stand and weed management in crop production. On-farm trials were, therefore, designed to (1) compare the response to nitrogen (N) rate of direct seeded and transplanted maize; (2) evaluate comparative performance of direct seeded and transplanted green maize under farmer management, and to work out the economics of transplanting; (3) investigate the effects of row spacing and atrazine dosage on weed dynamics maize yield; (4) determine the effects of inter-row spacing and plant population on weed dynamics and maize yield; and (5) investigate the effects of pre-plant weed control, N rate and plant population on weed dynamics and butternut yield. Maize transplanting improved crop stand, had earlier maturity and yielded higher at lower N rates compared to direct seeding for both green and grain maize. Total costs that varied were higher by R3 565 ha-1 for transplanted maize compared to direct-seeded maize, but the net benefits from transplanting were also much higher by R8 773 ha-1. Farmers favoured transplanting, citing bigger cobs, early maturity and the absence of seedling damage by birds, when maize was transplanted. However, a follow-up survey conducted during the subsequent year indicated that five of the six farmers abandoned transplanting, citing shortage of labour and high cost of commercially produced seedlings. It was concluded that transplanting is unlikely to be adopted unless the labour intensiveness of manual transplanting can be solved. Increasing atrazine dosage from a third of the label recommended dosage (LRD) and reducing row spacing from 90 to 45 cm resulted in an increase in weed mortality. A 100% kill of annual broadleaf weeds was possible while iv perennial grasses and the annual broadleaf weed, Oxalis latifolia, could not be controlled even at the LRD. However, improved weed mortality with increase in atrazine dosage and/or narrow rows did not translate into improved maize productivity. In butternut, pre-plant weed control resulted in a six-fold decrease in weed biomass and a 100% increase in fruit yield. These findings demonstrated the possibility of incorporation of reduced herbicide dosages and narrow rows to achieve adequate weed control and optimise on maize yields in smallholder farming systems. The results also suggested that pre-plant weed control is one of the pre-requisite to successful butternut production in SIS in South Africa. Increasing maize population from 40 000 to 60 000 plants ha-1 resulted in a 30% grain yield increase, but decreased length of cobs. Row spacing had no effect on maize yield at 40 000 plants ha-1, but at 60 000 plants ha-1 45 cm rows resulted in 11% higher grain yield (12 547 kg ha-1) than 90 cm rows (11 288 kg ha-1). Butternut yield increased significantly (p < 0.01) with increase in plant population and N rate. The optimum butternut population and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. Pre-plant weed control in butternut resulted in a six-fold decrease in weed biomass. Increasing butternut planting density from 10 000 to 30 000 plants ha-1 decreased weed biomass by 47%. No marketable fruits were obtained when planting was done without prior weed control. This result suggest that application of non-selective herbicide before planting is one technique that can be used by farmers as part of integrated weed management to give the crop a competitive advantage in the early growth stages before the plants start to produce vines. Yield increased significantly (p < 0.01) with increase in plant density and N rate. The optimum plant density and N rate were estimated at 25 000 plants ha-1 and 120 kg N ha-1, respectively. These findings emphasise the need to take into consideration production practices by farmers as a basis to build up skills in the management of crop enterprises and the farm as a viable business in any efforts to improve on the performance of SIS in South Africa. Future research should concentrate on labour-saving sustainable production technologies for SIS in South Africa.
- Full Text:
- Date Issued: 2010
Promoting social inclusion in school: reflecting on ourselves
- Authors: Geduld, Deidre Chante
- Date: 2010
- Subjects: Inclusive education -- South Africa -- Eastern Cape , Social integration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9445 , http://hdl.handle.net/10948/1522 , Inclusive education -- South Africa -- Eastern Cape , Social integration -- South Africa -- Eastern Cape
- Description: This thesis is an account of the transformation of my personal thinking and practice, as I developed my own new living theories about my practice. As I chose an action research approach for my research, my research is practice based, as outlined by Whitehead (1989), McNiff, Lomax and Whitehead (2003), McNiff and Whitehead (2005b), and Whitehead and McNiff (2006). As McNiff et al. (2003) explain, action research focuses on learning and embodies good professional practice and praxis; it will hopefully lead to personal and social improvement; it is a response to a social situation; it demands critical thinking and political intention; and the focus is on transformation within this thesis. The thesis comprises an account of my learning at both theoretical and practical levels, as I discovered how to live my values more fully in my practice. Inclusivity and leadership establish a set of values and purposes that underpins the educational process in a school. The individual commitment of the teachers and leader drives the values and purposes into reality. Values without implementation do little for school improvement. It is in dealing with the challenge to change and improve, often by confronting unacceptable practices, that teachers and leaders show their educational values. The thesis is the story of how I learned to speak for myself and came to regard her as a person who has something to say for herself in the context of the impoverished schools of South Africa. My thesis is an articulation of my belief that teachers and learners should be counted „among those with the authority to participate both in the critique and in the reform of education‟ (Cook-Sather, 2002:3). It also articulates my commitment to a scholarship of teaching that allows teachers to learn from pedagogical experience and exchange that learning in acts of scholarship that contribute to the wisdom of practice across the profession (Shulman, 1999:17). Collaborative and reflective discussion allowed me to capitalise on the social nature of learning. I not only considered how education could be used to assist children‟s growth, learning and development, but also applied the same concepts in the development, growth and learning of their teachers. I would argue that through my own work, I have attempted to establish a community of enquiry within my school that draws on a multi-generational model of knowledge production through bringing together teachers, researchers, students and critical friends.
- Full Text:
- Date Issued: 2010
- Authors: Geduld, Deidre Chante
- Date: 2010
- Subjects: Inclusive education -- South Africa -- Eastern Cape , Social integration -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9445 , http://hdl.handle.net/10948/1522 , Inclusive education -- South Africa -- Eastern Cape , Social integration -- South Africa -- Eastern Cape
- Description: This thesis is an account of the transformation of my personal thinking and practice, as I developed my own new living theories about my practice. As I chose an action research approach for my research, my research is practice based, as outlined by Whitehead (1989), McNiff, Lomax and Whitehead (2003), McNiff and Whitehead (2005b), and Whitehead and McNiff (2006). As McNiff et al. (2003) explain, action research focuses on learning and embodies good professional practice and praxis; it will hopefully lead to personal and social improvement; it is a response to a social situation; it demands critical thinking and political intention; and the focus is on transformation within this thesis. The thesis comprises an account of my learning at both theoretical and practical levels, as I discovered how to live my values more fully in my practice. Inclusivity and leadership establish a set of values and purposes that underpins the educational process in a school. The individual commitment of the teachers and leader drives the values and purposes into reality. Values without implementation do little for school improvement. It is in dealing with the challenge to change and improve, often by confronting unacceptable practices, that teachers and leaders show their educational values. The thesis is the story of how I learned to speak for myself and came to regard her as a person who has something to say for herself in the context of the impoverished schools of South Africa. My thesis is an articulation of my belief that teachers and learners should be counted „among those with the authority to participate both in the critique and in the reform of education‟ (Cook-Sather, 2002:3). It also articulates my commitment to a scholarship of teaching that allows teachers to learn from pedagogical experience and exchange that learning in acts of scholarship that contribute to the wisdom of practice across the profession (Shulman, 1999:17). Collaborative and reflective discussion allowed me to capitalise on the social nature of learning. I not only considered how education could be used to assist children‟s growth, learning and development, but also applied the same concepts in the development, growth and learning of their teachers. I would argue that through my own work, I have attempted to establish a community of enquiry within my school that draws on a multi-generational model of knowledge production through bringing together teachers, researchers, students and critical friends.
- Full Text:
- Date Issued: 2010
A chemo-enzymatic process for the production of beta-thymidine, a key intermediate in antiretrovirol manufacture
- Gordon, Gregory Ernest Robert
- Authors: Gordon, Gregory Ernest Robert
- Date: 2010
- Subjects: HIV infections -- Treatment -- South Africa , HIV infections -- South Africa -- Prevention , Antiretroviral agents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10423 , http://hdl.handle.net/10948/d1016217
- Description: The socio-economic impact of HIV/AIDS on South Africa has resulted in lower gross domestic product, loss of skills in key sectors such as education, and increased health-care costs in providing access to treatment. Currently active pharmaceutical ingredients (API’s) such as stavudine (d4T) and azidothymidine (AZT) are imported from India and China, while formulation is conducted locally. A strategy was initiated between CSIR Biosciences and LIFElab under the auspices of Arvir Technologies to investigate the feasibility of local antiretroviral manufacture (d4T and AZT) or the manufacture of a key intermediate such as β- thymidine (dT). Several advantages associated with successful implementation of this strategy include ensuring a local supply of API’s, thus reducing reliance on procurement from foreign sources and reducing the effect of foreign exchange rate fluctuations on providing cost effective access to treatment. A local supply source would also reduce the imports and thus aid the balance of payments deficit, and in addition to this, provide stimulus in the local pharmaceutical manufacturing industry (which has been in decline for several decades), resulting in increased skills and employment opportunities. This thesis describes the development of a superior chemo-enzymatic process for the production of β-thymidine (72 percent yield, prior to isolation), a key intermediate in the preparation of anti-retrovirals. Alternative processes based purely on chemical or bioprocess transformations to prepare either 5-methyluridine (5-MU) or dT suffer from several disadvantages: lengthy transformations due to protection/deprotection strategies, low selectivties and product yields (30 percent in the chemical process) and isolation of the product from dilute process streams requiring the use of large uneconomical reactors (bioprocesss). This contributes significantly to the cost of d4T and AZT manufacture. Our novel chemoenzymatic process comprises of a biocatalytic reaction for the production of 5-MU, with subsequent chemical transformation into dT (3 steps) negating and circumventing the limitations of the chemical or bioprocess routes. During the course of this project development, the β-thymidine selling price declined from 175 $/kg (2005) to 100 $/kg (2008). However, the process described in this work is still competitive based on the current β- thymidine selling price of 100 $/kg. The process economics show that with further optimization and increasing the isolated dT yield from 70 percent to 90 percent, the variable cost decreases from 136 $/kg to 110 $/kg. The increase in isolated yield is highly probable, based on solubility data of β-thymidine. The decrease in β-thymidine selling price and technological improvement in dT manufacture should translate into lower API manufacture costs and more cost effective access to treatment. Our novel biocatalytic process producing 5-MU uses a coupled enzyme system employing PNP, Purine Nucleoside Phosphorylase and PyNP, Pyrimidine Nucleoside Phosphorylase. The overall transglycosylation reaction may be decoupled into the phosphorolysis reaction (PNP) and synthesis reaction (PyNP). During the phosphorolysis reaction, guanosine is converted into guanine and ribose-1-phosphate (R-1-P) in the presence of PNP enzyme. The reaction intermediate R-1-P is then coupled to thymine in the presence of PyNP enzyme during the synthesis reaction, producing 5-MU. The process was scaled up from lab-scale to bench-scale (10 - 20 L) and demonstrated to be robust and reproducible. This is evident from the average guanosine conversion (94.7 percent ± 2.03) and 5-MU yield (88.2 percent ± 6.21) and mole balance (104 percent ± 7.61) which were obtained at bench-scale (3 replicates, 10 L). The reaction was carried out at reactor productivities of between 7 – 11 g.L-1.h-1. The integration of the biocatalytic process and chemical processes was successfully carried out, showing that 5-MU produced using our novel biocatalytic process behaved similarly to commercially available 5- MU (ex. Dayang Chemicals, China). A PCT patent application (Ref. No. P44422PC01) on this chemo-enzymatic process has been filed and currently public private partnerships are being explored through Arvir Technologies to evaluate and validate this technology at one ton scale.
- Full Text:
- Date Issued: 2010
- Authors: Gordon, Gregory Ernest Robert
- Date: 2010
- Subjects: HIV infections -- Treatment -- South Africa , HIV infections -- South Africa -- Prevention , Antiretroviral agents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10423 , http://hdl.handle.net/10948/d1016217
- Description: The socio-economic impact of HIV/AIDS on South Africa has resulted in lower gross domestic product, loss of skills in key sectors such as education, and increased health-care costs in providing access to treatment. Currently active pharmaceutical ingredients (API’s) such as stavudine (d4T) and azidothymidine (AZT) are imported from India and China, while formulation is conducted locally. A strategy was initiated between CSIR Biosciences and LIFElab under the auspices of Arvir Technologies to investigate the feasibility of local antiretroviral manufacture (d4T and AZT) or the manufacture of a key intermediate such as β- thymidine (dT). Several advantages associated with successful implementation of this strategy include ensuring a local supply of API’s, thus reducing reliance on procurement from foreign sources and reducing the effect of foreign exchange rate fluctuations on providing cost effective access to treatment. A local supply source would also reduce the imports and thus aid the balance of payments deficit, and in addition to this, provide stimulus in the local pharmaceutical manufacturing industry (which has been in decline for several decades), resulting in increased skills and employment opportunities. This thesis describes the development of a superior chemo-enzymatic process for the production of β-thymidine (72 percent yield, prior to isolation), a key intermediate in the preparation of anti-retrovirals. Alternative processes based purely on chemical or bioprocess transformations to prepare either 5-methyluridine (5-MU) or dT suffer from several disadvantages: lengthy transformations due to protection/deprotection strategies, low selectivties and product yields (30 percent in the chemical process) and isolation of the product from dilute process streams requiring the use of large uneconomical reactors (bioprocesss). This contributes significantly to the cost of d4T and AZT manufacture. Our novel chemoenzymatic process comprises of a biocatalytic reaction for the production of 5-MU, with subsequent chemical transformation into dT (3 steps) negating and circumventing the limitations of the chemical or bioprocess routes. During the course of this project development, the β-thymidine selling price declined from 175 $/kg (2005) to 100 $/kg (2008). However, the process described in this work is still competitive based on the current β- thymidine selling price of 100 $/kg. The process economics show that with further optimization and increasing the isolated dT yield from 70 percent to 90 percent, the variable cost decreases from 136 $/kg to 110 $/kg. The increase in isolated yield is highly probable, based on solubility data of β-thymidine. The decrease in β-thymidine selling price and technological improvement in dT manufacture should translate into lower API manufacture costs and more cost effective access to treatment. Our novel biocatalytic process producing 5-MU uses a coupled enzyme system employing PNP, Purine Nucleoside Phosphorylase and PyNP, Pyrimidine Nucleoside Phosphorylase. The overall transglycosylation reaction may be decoupled into the phosphorolysis reaction (PNP) and synthesis reaction (PyNP). During the phosphorolysis reaction, guanosine is converted into guanine and ribose-1-phosphate (R-1-P) in the presence of PNP enzyme. The reaction intermediate R-1-P is then coupled to thymine in the presence of PyNP enzyme during the synthesis reaction, producing 5-MU. The process was scaled up from lab-scale to bench-scale (10 - 20 L) and demonstrated to be robust and reproducible. This is evident from the average guanosine conversion (94.7 percent ± 2.03) and 5-MU yield (88.2 percent ± 6.21) and mole balance (104 percent ± 7.61) which were obtained at bench-scale (3 replicates, 10 L). The reaction was carried out at reactor productivities of between 7 – 11 g.L-1.h-1. The integration of the biocatalytic process and chemical processes was successfully carried out, showing that 5-MU produced using our novel biocatalytic process behaved similarly to commercially available 5- MU (ex. Dayang Chemicals, China). A PCT patent application (Ref. No. P44422PC01) on this chemo-enzymatic process has been filed and currently public private partnerships are being explored through Arvir Technologies to evaluate and validate this technology at one ton scale.
- Full Text:
- Date Issued: 2010
A contribution to TEC modelling over Southern Africa using GPS data
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
- Authors: Habarulema, John Bosco
- Date: 2010
- Subjects: Electrons -- Mathematical models Radio wave propagation Global positioning system -- Measurement Ionospheric radio wave propagation Atmospheric physics -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5456 , http://hdl.handle.net/10962/d1005241
- Description: Modelling ionospheric total electron content (TEC) is an important area of interest for radio wave propagation, geodesy, surveying, the understanding of space weather dynamics and error correction in relation to Global Navigation Satellite Systems (GNNS) applications. With the utilisation of improved ionosonde technology coupled with the use of GNSS, the response of technological systems due to changes in the ionosphere during both quiet and disturbed conditions can be historically inferred. TEC values are usually derived from GNSS measurements using mathematically intensive algorithms. However, the techniques used to estimate these TEC values depend heavily on the availability of near-real time GNSS data, and therefore, are sometimes unable to generate complete datasets. This thesis investigated possibilities for the modelling of TEC values derived from the South African Global Positioning System (GPS)receiver network using linear regression methods and artificial neural networks (NNs). GPS TEC values were derived using the Adjusted Spherical Harmonic Analysis (ASHA) algorithm. Considering TEC and the factors that influence its variability as “dependent and independent variables” respectively, the capabilities of linear regression methods and NNs for TEC modelling were first investigated using a small dataset from two GPS receiver stations. NN and regression models were separately developed and used to reproduce TEC fluctuations at different stations not included in the models’ development. For this purpose, TEC was modelled as a function of diurnal variation, seasonal variation, solar and magnetic activities. Comparative analysis showed that NN models provide predictions of GPS TEC that were an improvement on those predicted by the regression models developed. A separate study to empirically investigate the effects of solar wind on GPS TEC was carried out. Quantitative results indicated that solar wind does not have a significant influence on TEC variability. The final TEC simulation model developed makes use of the NN technique to find the relationship between historical TEC data variations and factors that are known to influence TEC variability (such as solar and magnetic activities, diurnal and seasonal variations and the geographical locations of the respective GPS stations) for the purposes of regional TEC modelling and mapping. The NN technique in conjunction with interpolation and extrapolation methods makes it possible to construct ionospheric TEC maps and to analyse the spatial and temporal TEC behaviour over Southern Africa. For independent validation, modelled TEC values were compared to ionosonde TEC and the International Reference Ionosphere (IRI) generated TEC values during both quiet and disturbed conditions. This thesis provides a comprehensive guide on the development of TEC models for predicting ionospheric variability over the South African region, and forms a significant contribution to ionospheric modelling efforts in Africa.
- Full Text:
- Date Issued: 2010
Psigobiografiese persoonlikheidsbeskrywing van Generaal Christiaan de Wet
- Authors: Henning, Riana
- Date: 2010
- Subjects: De Wet, Christiaan Rudolf, 1854-1922 Psychology -- Biographical methods Psychoanalysis Big Five model Politicians -- Psychology South Africa -- Politics and government -- 1836-1909 South Africa -- Politics and government -- 1909-1948
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2990 , http://hdl.handle.net/10962/d1002499
- Description: Hierdie is 'n psigobiografiese studie van Generaal Christiaan Rudolph de Wet. 'n Psigobiografiese studie is die bestudering van 'n persoon se volledige lewe met die doel om die persoon beter te verstaan. Psigobiografiese navorsing maak gebruik van psigologiese teorieë wat aangewend word om die biografiese data van 'n persoon se lewe te beskryf en moontlik ook te verklaar. Die individu wat bestudeer word, is gewoonlik 'n bekende, invloedryke, navolgenswaardige, interessante of modelfiguur. Daar is tans 'n oplewing in die veld van psigobiografiese studies, maar daar word nog steeds nie genoeg in die akademiese veld gedoen om psigobiografiese studies te bevorder nie. De Wet (1854-1922) is vir hierdie studie gekies omdat hy 'n interessante, dog komplekse figuur was. Hy het veral tydens die Anglo-Boereoorlog in 1899-1902 bekendheid verwerf. As 45-jarige man het De Wet in die Anglo-Boereoorlog geveg en vinnig opgang as 'n militêre leier gemaak. Sy vindingryke ontsnappingspogings het die Britse magte hoofbrekens besorg. Wat De Wet verder uniek maak, is dat hy met net drie maande skoolopleiding in die parlement gedien het, as president verkies is, die hoogste gesag in die Verdedigingsmag gehad het en 'n boek oor sy oorlogsherinneringe geskryf het. Alhoewel daar akademiese werke oor De Wet bestaan, is daar tot op hede nog geen psigobiografiese studie oor hom gedoen nie. Die doel van die studie was om die mens agter die legende na vore te bring. Daar is ook gepoog om moontlike antwoorde en verklarings op onbeantwoorde vrae te gee. Die studie het van beide kwalitatiewe en kwantitatiewe data gebruik gemaak en kan as 'n psigobiografiese gevalstudie beskryf word. Die Vyf-faktor model van Costa en McCrae (1992) is op die biografiese data van De Wet toegepas om sodoende sy persoonlikheidseienskappe te beskryf. Die bevindinge het interessante persoonlikheidseienskappe van De Wet deur middel van die Vyf-faktor model aan die lig gebring. Volgens die kwalitatiewe navorsingsbevindinge was De Wet 'n vyandige, aksie-gedrewe, bevoegde, prestasie-strewende, selfgedissiplineerde, warm, openhartige, saggeaarde en beskeie persoon. Die kwalitatiewe en kwantitatiewe data-ontledings het uiteenlopende persoonlikheidskenmerke by De Wet geïdentifiseer. Die grootste verskille het by die fasette warmte, openhartigheid en altruïsme voorgekom. Die waarde van die studie is dat 'n wetenskaplike persoonlikheidsontleding van De Wet gedoen is. Dit is ook die eerste studie waar 'n teoretiese model op De Wet se persoonlikheid toegepas is. Alhoewel die studie sekere tekortkominge toon, beklemtoon dit terselfdertyd die wenslikheid daarvan om alternatiewe modelle te gebruik tydens die ontleding van persoonlikheidskenmerke. Die studie dui ook op die behoefte aan verdere navorsing, byvoorbeeld soortgelyke ontledings en vergelykings van die persoonlikhede van ander militêre bevelvoerders (De la Rey, Smuts, Beyers, Hertzog).
- Full Text:
- Date Issued: 2010
- Authors: Henning, Riana
- Date: 2010
- Subjects: De Wet, Christiaan Rudolf, 1854-1922 Psychology -- Biographical methods Psychoanalysis Big Five model Politicians -- Psychology South Africa -- Politics and government -- 1836-1909 South Africa -- Politics and government -- 1909-1948
- Language: Afrikaans
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2990 , http://hdl.handle.net/10962/d1002499
- Description: Hierdie is 'n psigobiografiese studie van Generaal Christiaan Rudolph de Wet. 'n Psigobiografiese studie is die bestudering van 'n persoon se volledige lewe met die doel om die persoon beter te verstaan. Psigobiografiese navorsing maak gebruik van psigologiese teorieë wat aangewend word om die biografiese data van 'n persoon se lewe te beskryf en moontlik ook te verklaar. Die individu wat bestudeer word, is gewoonlik 'n bekende, invloedryke, navolgenswaardige, interessante of modelfiguur. Daar is tans 'n oplewing in die veld van psigobiografiese studies, maar daar word nog steeds nie genoeg in die akademiese veld gedoen om psigobiografiese studies te bevorder nie. De Wet (1854-1922) is vir hierdie studie gekies omdat hy 'n interessante, dog komplekse figuur was. Hy het veral tydens die Anglo-Boereoorlog in 1899-1902 bekendheid verwerf. As 45-jarige man het De Wet in die Anglo-Boereoorlog geveg en vinnig opgang as 'n militêre leier gemaak. Sy vindingryke ontsnappingspogings het die Britse magte hoofbrekens besorg. Wat De Wet verder uniek maak, is dat hy met net drie maande skoolopleiding in die parlement gedien het, as president verkies is, die hoogste gesag in die Verdedigingsmag gehad het en 'n boek oor sy oorlogsherinneringe geskryf het. Alhoewel daar akademiese werke oor De Wet bestaan, is daar tot op hede nog geen psigobiografiese studie oor hom gedoen nie. Die doel van die studie was om die mens agter die legende na vore te bring. Daar is ook gepoog om moontlike antwoorde en verklarings op onbeantwoorde vrae te gee. Die studie het van beide kwalitatiewe en kwantitatiewe data gebruik gemaak en kan as 'n psigobiografiese gevalstudie beskryf word. Die Vyf-faktor model van Costa en McCrae (1992) is op die biografiese data van De Wet toegepas om sodoende sy persoonlikheidseienskappe te beskryf. Die bevindinge het interessante persoonlikheidseienskappe van De Wet deur middel van die Vyf-faktor model aan die lig gebring. Volgens die kwalitatiewe navorsingsbevindinge was De Wet 'n vyandige, aksie-gedrewe, bevoegde, prestasie-strewende, selfgedissiplineerde, warm, openhartige, saggeaarde en beskeie persoon. Die kwalitatiewe en kwantitatiewe data-ontledings het uiteenlopende persoonlikheidskenmerke by De Wet geïdentifiseer. Die grootste verskille het by die fasette warmte, openhartigheid en altruïsme voorgekom. Die waarde van die studie is dat 'n wetenskaplike persoonlikheidsontleding van De Wet gedoen is. Dit is ook die eerste studie waar 'n teoretiese model op De Wet se persoonlikheid toegepas is. Alhoewel die studie sekere tekortkominge toon, beklemtoon dit terselfdertyd die wenslikheid daarvan om alternatiewe modelle te gebruik tydens die ontleding van persoonlikheidskenmerke. Die studie dui ook op die behoefte aan verdere navorsing, byvoorbeeld soortgelyke ontledings en vergelykings van die persoonlikhede van ander militêre bevelvoerders (De la Rey, Smuts, Beyers, Hertzog).
- Full Text:
- Date Issued: 2010
Hotel rating through guest feedback
- Authors: Hensens, Wouter
- Date: 2010
- Subjects: Hospitality industry -- Customer services , Hotels , Hotels -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9264 , http://hdl.handle.net/10948/1631 , Hospitality industry -- Customer services , Hotels , Hotels -- Evaluation
- Description: Hotel rating refers to the process where the comfort and services of a hotel are assessed and classified, usually in five categories, using stars as symbols. Conventional hotel rating systems are generally operated by governments or independent parties. However, with the growth of social media and customer-review sites, guest review platforms became an important source of information. The main aim of this study is to establish whether guest feedback can determine hotel ratings more accurately than conventional methods and whether a social media platform such as TripAdvisor can provide the necessary data to do so. The customer-review website, TripAdvisor, has grown rapidly and made a strong impact on the tourism and hotel industry. This study identifies the nature of TripAdvisor, its reliability, how its ratings compare with conventional ratings, and what criteria are used in guest reviews on TripAdvisor when assessing the quality of a hotel. These findings were triangulated with findings from the conventional rating systems of the 11 destinations that were sampled for this study to identify the value of TripAdvisor. Two samples were taken from TripAdvisor of 110 and 33 hotels, respectively. From the latter, ten guest reviews were gathered and analysed per hotel, resulting in a total of 330 reviews that were analysed. The study’s findings indicate that TripAdvisor is the largest guest feedback platform for hotels and its data can be considered to be reliable. The TripAdvisor ratings were not connected to the conventional ratings of the sampled hotels. The criteria used in TripAdvisor reviews focused more on service delivery than on the objective tangible elements used in most hotel rating systems. The rich context found in most guest reviews makes the information presented on TripAdvisor valuable. There is no evidence that conventionalrating system controls are linked to the comments found in TripAdvisor reviews. The results facilitated the identification of the delight and frustration factors in services marketing for the hotel industry. A new theory to include guest feedback in hotel ratings is developed and proposed. The study further presents two future scenarios, the most likely one of which predicts the demise of conventional rating systems as a result of the success of guest feedback platforms such as TripAdvisor.
- Full Text:
- Date Issued: 2010
- Authors: Hensens, Wouter
- Date: 2010
- Subjects: Hospitality industry -- Customer services , Hotels , Hotels -- Evaluation
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:9264 , http://hdl.handle.net/10948/1631 , Hospitality industry -- Customer services , Hotels , Hotels -- Evaluation
- Description: Hotel rating refers to the process where the comfort and services of a hotel are assessed and classified, usually in five categories, using stars as symbols. Conventional hotel rating systems are generally operated by governments or independent parties. However, with the growth of social media and customer-review sites, guest review platforms became an important source of information. The main aim of this study is to establish whether guest feedback can determine hotel ratings more accurately than conventional methods and whether a social media platform such as TripAdvisor can provide the necessary data to do so. The customer-review website, TripAdvisor, has grown rapidly and made a strong impact on the tourism and hotel industry. This study identifies the nature of TripAdvisor, its reliability, how its ratings compare with conventional ratings, and what criteria are used in guest reviews on TripAdvisor when assessing the quality of a hotel. These findings were triangulated with findings from the conventional rating systems of the 11 destinations that were sampled for this study to identify the value of TripAdvisor. Two samples were taken from TripAdvisor of 110 and 33 hotels, respectively. From the latter, ten guest reviews were gathered and analysed per hotel, resulting in a total of 330 reviews that were analysed. The study’s findings indicate that TripAdvisor is the largest guest feedback platform for hotels and its data can be considered to be reliable. The TripAdvisor ratings were not connected to the conventional ratings of the sampled hotels. The criteria used in TripAdvisor reviews focused more on service delivery than on the objective tangible elements used in most hotel rating systems. The rich context found in most guest reviews makes the information presented on TripAdvisor valuable. There is no evidence that conventionalrating system controls are linked to the comments found in TripAdvisor reviews. The results facilitated the identification of the delight and frustration factors in services marketing for the hotel industry. A new theory to include guest feedback in hotel ratings is developed and proposed. The study further presents two future scenarios, the most likely one of which predicts the demise of conventional rating systems as a result of the success of guest feedback platforms such as TripAdvisor.
- Full Text:
- Date Issued: 2010
Induced plant responses of different Lantana camara L. (Verbenaceae) varieties to herbivory by Falconia intermedia (distant) (Hemiptera: Miridae)
- Heshula, Unathi-Nkosi Lelethu Peter
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
- Authors: Heshula, Unathi-Nkosi Lelethu Peter
- Date: 2010
- Subjects: Lantana camara -- South Africa -- Eastern Cape , Lantana camara -- Biological control -- South Africa -- Eastern Cape , Biological pest control agents -- South Africa -- Eastern Cape , Weeds -- Biological control -- South Africa -- Eastern Cape , Invasive plants -- Biological control -- South Africa -- Eastern Cape , Hemiptera -- South Africa -- Eastern Cape , Miridae -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5911 , http://hdl.handle.net/10962/d1015368
- Description: A highly variable invasive shrub, Lantana camara L. (Verbenaceae), has been notoriously difficult to control thus far despite a well established biological control programme in South Africa. A promising leaf-feeding biological control agent, Falconia intermedia (Distant) (Hemiptera: Miridae), released to control this invasive plant eventually crashed at three out of five sites in the Eastern Cape Province. In the Mpumalanga Province, after initially colonising and building up high numbers on the L. camara stands the agent populations crashed. Several reasons for these population crashes have been suggested, but induced plant defences have not been investigated. Although plants face the challenge of herbivory by various organisms while remaining immobile, some plants may possess the ability to induce physical and/or chemical defensive responses following feeding and thus prevent further plant tissue damage and loss. Laboratory trials were conducted to determine the existence, nature and effect of physical and chemical feeding-induced responses of L. camara on the performance of the leaf-feeding biological control agent, F. intermedia. Lantana camara plants used in the study were obtained from five localities in the Eastern Cape Province, South Africa, while the insect culture was established from field populations. Plants from all varieties on which F. intermedia was released significantly increased the toughness of their leaves compared to control treatment plants. In addition, plants from three localities: Lyndhurst Farm, East London and Port Alfred, significantly increased trichome density after prolonged feeding by F. intermedia. On the three varieties showing increases in these two factors (i.e. leaf toughness and trichome density), oviposition, survival and feeding damage by the mirid agent was significantly lower on previously damaged plants. A significant negative correlation between trichome density and population numbers was found (R²= 0.52, p < 0.0003), suggesting that an increase in trichome density strongly contributes to a reduction in F. intermedia's growth. The growth and reproduction of the resistant plants was not significantly impacted by F. intermedia feeding. The defensive responses were found to be plant systemic and rapidly induced as they were elicited and expressed throughout the plant in both damaged and undamaged leaves within five weeks after insect release. Leaf toughness and trichome density were not significantly increased after feeding on plants from Whitney Farm and Heather Glen Farm. On the contrary, mirid individuals performed significantly better on plants from Whitney Farm and Heather Glen Farm than on plants of other varieties, indicating their susceptibility and suitability to the agent and the lack of induced resistance against the agent. Plants from all localities besides East London showed some level of tolerance and overcompensated for feeding damage by increasing plant growth and reproductive factors on plants fed upon. This was however only significant in two variables of the more susceptible localities, Whitney Farm and Heather Glen Farm. This increase in plant fitness did however indicate an induced defence response by these plants to feeding, a response designed to lessen the effects of agent feeding. Headspace volatile analysis was used to investigate any volatile chemical responses by L. camara due to F. intermedia feeding at two of the five localities chosen: East London and Whitney Farm. There was no significant difference in headspace volatiles emitted by leaves of plants from the East London insect infested and control treatment plants. On the Whitney Farm damaged plants however there was a 2.5 fold increase in the emission intensity of one of the three main compounds, later identified as Beta-caryophyllene. Three major chemical constituents which were found to be common to leaf volatiles of the two varieties were identified through gas chromatography-mass spectrometry (GC-MS) from the damaged and undamaged leaves of these two varieties. The methods used in collecting leaf volatiles were shown to be significant in the strength of chromatogram peaks. Using general authentication methods and purified standards, one of these was identified as the sesquiterpene, Beta-caryophyllene (C₁₅H₂₄). This compound is one of the major constituents found in isolations of L. camara varieties worldwide. This is the first such work done on a variety of L. camara in South Africa, and hopefully the beginning of more in-depth studies of the volatile organic chemicals from the numerous naturalised varieties of L. camara. It is suggested that the sum of these responses may play a role bigger than is currently understood in this plant-insect relationship. It is also argued that feeding induced plant defences may play an important role in attempts to control alien plants using insect agents.
- Full Text:
- Date Issued: 2010
The impact of the Western conceptualization of the Christian gospel on its communication in a non-Western environment, with particular reference to the AmaXhosa
- Authors: Higgs, Michael John
- Date: 2010
- Subjects: Christianity and culture -- South Africa , Church history , Missions -- South Africa -- Eastern Cape , Xhosa (African people) -- Religion , Communication -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , D Th
- Identifier: vital:11800 , http://hdl.handle.net/10353/356 , Christianity and culture -- South Africa , Church history , Missions -- South Africa -- Eastern Cape , Xhosa (African people) -- Religion , Communication -- Religious aspects -- Christianity
- Description: This thesis examines the extent and nature of the impact of the contextualization of Christianity upon the amaXhosa from the missionary irruption in the nineteenth century to the present day, and proceeds to examine the implications of this impact for the presentation of the Christian gospel in the contemporary Eastern Cape. Chapter One describes the problem, offers definitions of key concepts and outlines the procedural method for the rest of the thesis. Chapter Two deals with the question of the cross-cultural communication of the Christian gospel in theory. Doctrinal questions such as the nature of the gospel are examined. The basic hermeneutical issue of the categorization of doctrinal tenets according to whether they are required or simply permitted is discussed in terms of Osborne's categories: 'cardinal', 'non-cardinal'. Tenets which are found to be 'anti-scriptural' would be rejected. Specific hermeneutical topics such as language and meaning, symbolics, textuality and orality are then discussed. This is followed by a survey of secular influences which affect a conceptualization. This chapter is preparatory to, and definitive for, the discourse which follows. Chapter Three outlines the cultural heritage from which the Western missionary contextualization of Christianity developed. It shows the extent to which this presentation of the gospel was dependent upon the philosophy which Britain and Europe inherited from the classical Greek culture. More modern developments such as the Enlightenment, Empiricism and Historicism bring the discourse up to the point at which the missionaries arrived. Chapter Four deals with the initial encounter between the missionaries and the amaXhosa. A brief account is given of the nature of the religious and spiritual aspects of the Xhosa culture which first encountered Christianity. The doctrinal section of this chapter deals with those doctrines in the missionary message which became issues for the amaXhosa. The hermeneutical section shows how the cultural setting of the West (vii) affected both the contextualization by the missionaries and the conceptualization by the amaXhosa. To a large extent, the missionaries made the double mistake of imposing their culture on the amaXhosa and failing to accord respect, even recognition, to the Xhosa culture. This amounted to imperialism, which, together with the political imperialism of Britain as the colonizing power, evoked responses from the Xhosa community which are outlined in section 4.4, including those of Nxele and Ntsikana. Because the impact of the Western contextualization is an on-going phenomenon, the thesis continues to trace its development up to the present time. Apartheid is briefly mentioned in Chapter Five. The point is made that all white people were perceived by the amaXhosa to be Christians, and the architects and practitioners of apartheid claimed to be Christians. This ideology therefore had a direct effect on the Xhosa conceptualization of the gospel. The architects of apartheid actually believed that they were accepting God's gift and mandate. This chapter includes Black theological reaction to apartheid in terms of the South African version of Liberation theology. Chapter Six returns to Western Theology in order to bring the sphere of discourse from the point at which it left off at the end of Chapter Three up to the present time. The schools of thought in this period are: Secularism and Existentialism, together with their theological extension, Demythologization. The main religious movements are the Charismatic Movement and Neo-Pentecostalism. Postmodernism came as a later philosophical school, to be followed by Globality. Chapter Seven deals with black South African reactive and proactive responses. The predominant theologies are those of Dwane, Buthelezi, Boesak and Mtuze. Although Dwane, Buthelezi and Boesak came on the scene at the same time as the black theologians reviewed in Chapter Five, their work is placed here because it differs significantly from the more radical responses of the latter. Mtuze is post-apartheid, and responds to the developments outlined in Chapter Six. Chapter Eight draws the findings of the thesis together, by considering how the Christian Gospel ought to be presented to the various contemporary sub-cultures of the amaXhosa. (viii) The last Chapter applies the findings of the thesis to the task in hand. The desired outcomes are listed and briefly discussed. The task ahead is enunciated in terms of manpower and other resources for the effective communication of the Christian gospel in the twenty-first century. The past, present and projected programmes of the Bible Institute Eastern Cape [the target institution] are described and assessed. Finally, topics which presented themselves in the course of the preparation of this thesis are suggested for future research.
- Full Text:
- Date Issued: 2010
- Authors: Higgs, Michael John
- Date: 2010
- Subjects: Christianity and culture -- South Africa , Church history , Missions -- South Africa -- Eastern Cape , Xhosa (African people) -- Religion , Communication -- Religious aspects -- Christianity
- Language: English
- Type: Thesis , Doctoral , D Th
- Identifier: vital:11800 , http://hdl.handle.net/10353/356 , Christianity and culture -- South Africa , Church history , Missions -- South Africa -- Eastern Cape , Xhosa (African people) -- Religion , Communication -- Religious aspects -- Christianity
- Description: This thesis examines the extent and nature of the impact of the contextualization of Christianity upon the amaXhosa from the missionary irruption in the nineteenth century to the present day, and proceeds to examine the implications of this impact for the presentation of the Christian gospel in the contemporary Eastern Cape. Chapter One describes the problem, offers definitions of key concepts and outlines the procedural method for the rest of the thesis. Chapter Two deals with the question of the cross-cultural communication of the Christian gospel in theory. Doctrinal questions such as the nature of the gospel are examined. The basic hermeneutical issue of the categorization of doctrinal tenets according to whether they are required or simply permitted is discussed in terms of Osborne's categories: 'cardinal', 'non-cardinal'. Tenets which are found to be 'anti-scriptural' would be rejected. Specific hermeneutical topics such as language and meaning, symbolics, textuality and orality are then discussed. This is followed by a survey of secular influences which affect a conceptualization. This chapter is preparatory to, and definitive for, the discourse which follows. Chapter Three outlines the cultural heritage from which the Western missionary contextualization of Christianity developed. It shows the extent to which this presentation of the gospel was dependent upon the philosophy which Britain and Europe inherited from the classical Greek culture. More modern developments such as the Enlightenment, Empiricism and Historicism bring the discourse up to the point at which the missionaries arrived. Chapter Four deals with the initial encounter between the missionaries and the amaXhosa. A brief account is given of the nature of the religious and spiritual aspects of the Xhosa culture which first encountered Christianity. The doctrinal section of this chapter deals with those doctrines in the missionary message which became issues for the amaXhosa. The hermeneutical section shows how the cultural setting of the West (vii) affected both the contextualization by the missionaries and the conceptualization by the amaXhosa. To a large extent, the missionaries made the double mistake of imposing their culture on the amaXhosa and failing to accord respect, even recognition, to the Xhosa culture. This amounted to imperialism, which, together with the political imperialism of Britain as the colonizing power, evoked responses from the Xhosa community which are outlined in section 4.4, including those of Nxele and Ntsikana. Because the impact of the Western contextualization is an on-going phenomenon, the thesis continues to trace its development up to the present time. Apartheid is briefly mentioned in Chapter Five. The point is made that all white people were perceived by the amaXhosa to be Christians, and the architects and practitioners of apartheid claimed to be Christians. This ideology therefore had a direct effect on the Xhosa conceptualization of the gospel. The architects of apartheid actually believed that they were accepting God's gift and mandate. This chapter includes Black theological reaction to apartheid in terms of the South African version of Liberation theology. Chapter Six returns to Western Theology in order to bring the sphere of discourse from the point at which it left off at the end of Chapter Three up to the present time. The schools of thought in this period are: Secularism and Existentialism, together with their theological extension, Demythologization. The main religious movements are the Charismatic Movement and Neo-Pentecostalism. Postmodernism came as a later philosophical school, to be followed by Globality. Chapter Seven deals with black South African reactive and proactive responses. The predominant theologies are those of Dwane, Buthelezi, Boesak and Mtuze. Although Dwane, Buthelezi and Boesak came on the scene at the same time as the black theologians reviewed in Chapter Five, their work is placed here because it differs significantly from the more radical responses of the latter. Mtuze is post-apartheid, and responds to the developments outlined in Chapter Six. Chapter Eight draws the findings of the thesis together, by considering how the Christian Gospel ought to be presented to the various contemporary sub-cultures of the amaXhosa. (viii) The last Chapter applies the findings of the thesis to the task in hand. The desired outcomes are listed and briefly discussed. The task ahead is enunciated in terms of manpower and other resources for the effective communication of the Christian gospel in the twenty-first century. The past, present and projected programmes of the Bible Institute Eastern Cape [the target institution] are described and assessed. Finally, topics which presented themselves in the course of the preparation of this thesis are suggested for future research.
- Full Text:
- Date Issued: 2010
Surveillance of invasive vibro species in discharged aqueous efflents of wastewater treatment plants in the Eastern Cape province of South Africa
- Authors: Igbinosa, Etinosa Ogbomoede
- Date: 2010
- Subjects: Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11267 , http://hdl.handle.net/10353/245 , Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.
- Full Text:
- Date Issued: 2010
- Authors: Igbinosa, Etinosa Ogbomoede
- Date: 2010
- Subjects: Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , PhD (Microbiology)
- Identifier: vital:11267 , http://hdl.handle.net/10353/245 , Vibrio -- South Africa -- Eastern Cape , Water -- Fluoridation -- South Africa -- Eastern Cape , Water -- Pollution -- South Africa -- Eastern Cape , Effluent quality -- South Africa -- Eastern Cape , Water -- Purification -- South Africa -- Eastern Cape
- Description: Vibrio infections remain a serious threat to public health. In the last decade, Vibrio disease outbreaks have created a painful awareness of the personal, economic, societal, and public health costs associated with the impact of contaminated water in the aquatic milieu. This study was therefore designed to assess the prevalence of Vibrio pathogens in the final effluents of wastewater treatment plants (WWTPs) in the Eastern Cape Province, as well as their abilities to survive the treatment processes of the activated sludge system either as free cells or as plankton-associated entities in relation to the physicochemical qualities of the effluents. Three wastewater treatment facilities were selected to represent typical urban, sub-urban and rural communities, and samples were collected monthly from August 2007 to July 2008 from the final effluent, discharge point, 500 meter upstream and downstream of the discharge points and analysed for physicochemical parameters, Vibrio pathogens prevalence and their antibiogram characteristics using both culture based and molecular techniques. Physicochemical parameters measured include pH, temperature, electrical conductivity, salinity, turbidity, total dissolved solid (TDS), dissolved oxygen (DO), chemical oxygen demand (COD), nitrate, nitrite and orthophosphate levels. Unacceptably high levels of the assayed parameters were observed in many cases for COD (<10 - 1180 mg/l), nitrate (0.08 - 13.14 mg NO3- as N/l), nitrite (0.06 - 6.78 mg NO2- as N/l), orthophosphate (0.07-4.81 mg PO43- as P/l), DO (1.24 - 11.22 mg/l) and turbidity (2.04 -159.06 NTU). Temperature, COD and nitrite varied significantly with season (P < 0.05), while pH, EC, salinity, TDS, COD, and nitrate all varied significantly with sampling site (P < 0.01; P < 0.05). In the rural wastewater treatment facility, free-living Vibrio densities varied from 0 to 3.45 × 101 cfu ml-1, while the plankton-associated Vibrio densities vary with plankton sizes as follows: 180 μm (0 – 4.50 × 103 cfu ml-1); 60 μm (0 – 4.86 × 103 cfu ml-1); 20 μm (0 – 1.9 × 105 cfu ml-1). The seasonal variations in the Vibrio densities in the 180 and 60 μm plankton size samples were significant (P < 0.05), while the 20 μm plankton size and free-living vibrios densities were not. Molecular confirmation of the presumptive vibrios isolates revealed V. fluvialis (36.5 percent), as the predominant species, followed by V. vulnificus (34.6 percent), and V. parahaemolyticus (23.1 percent), and V. metschnikovii (5.8 percent) (detected using only API 20 NE), suggesting high incidence of pathogenic Vibrio species in the final effluent of the wastewater facility. Correlation analysis suggested that the concentration of Vibrio species correlated negatively with salinity and temperature (P < 0.001 and P < 0.002 respectively) as well as with pH and turbidity (P < 0.001), in the final effluent. Population density of total Vibrio ranged from 2.1 × 101 to 4.36 × 104 cfu ml-1 and from 2.80 ×101 to 1.80 × 105 cfu ml-1 for the sub-urban and urban communities treatment facilities respectively. Vibrio species associated with 180 μm, 60 μm, and 20 μm plankton sizes, were observed at densities of 0 - 1.36 × 103 cfu ml-1, 0 - 8.40 × 102 cfu ml-1 and 0 - 6.80 × 102 cfu ml-1 respectively at the sub-urban community‘s WWTP. In the urban community, counts of culturable vibrios ranged from 0 - 2.80 × 102 cfu ml-1 (180 μm); 0 - 6.60 × 102 cfu ml-1 (60 μm) and 0 -1.80 × 103 cfu ml-1 (20 μm). Abundance of free-living Vibrio species varied between 0 and the orders of 102 and 103 cfu ml-1 in the sub-urban and urban communities WWTPs respectively. Molecular confirmation of the presumptive vibrios isolates revealed the presence of V. fluvialis (41.38 percent), V. vulnificus (34.48 percent), and V. parahaemolyticus (24.14 percent) in the sub-urban community effluents. In the urban community V. fluvialis (40 percent), V. vulnificus (36 percent), and V. parahaemolyticus (24 percent) were detected. There was no significant correlation between Vibrio abundance and season, either as free-living or plankton-associated entities, while Vibrio species abundance correlated positively with temperature (r = 0.565; P < 0.01), salinity and dissolved oxygen (P < 0.05). Turbidity and pH showed significant seasonal variation (P < 0.05) in both locations. The Vibrio strains showed the typical multi-antibiotic-resistance of an SXT element. They were resistant to sulfamethoxazole (Sul), trimethoprim (Tmp), cotrimoxazole (Cot), chloramphenicol (Chl) and streptomycin (Str), as well as other antibiotics such as ampicillin (Amp), penicillin (Pen), erythromycin (Ery), tetracycline (Tet), nalidixic acid (Nal), and gentamicin (Gen). The antibiotic resistance genes detected includes dfr18 and dfrA1 for trimethoprim; tetA, strB, floR, sul2 blaP1, for tetracycline, streptomycin, chloramphenicol, sulfamethoxazole and β-lactams respectively. A number of these genes were only recently described from clinical isolates, demonstrating genetic exchange between clinical and environmental Vibrio species. This study revealed that there was an adverse impact on the physicochemical characteristics of the receiving watershed as a result of the discharge of inadequately treated effluents from the wastewater treatment facilities. The occurrence of Vibrio species as plankton-associated entities confirms the role of plankton as potential reservoir for this pathogen. Also the treated final effluents are reservoirs of various antibiotics resistance genes. This could pose significant health and environmental risk to the biotic component of the environment including communities that rely on the receiving water for domestic purposes and may also affect the health status of the aquatic milieu in the receiving water. There is need for consistent monitoring programme by appropriate regulatory agencies to ensure compliance of the wastewater treatment facilities to regulatory effluent quality standards.
- Full Text:
- Date Issued: 2010