The effect of human soluble FceRII on the RPMI 8866 B-Lymphoblastoid and the U937 Monocyte cell lines
- Authors: Daniels, Brodie Belinda
- Date: 2003
- Subjects: Developmental inmmunology , Cellular control mechanisms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11084 , http://hdl.handle.net/10948/322 , Developmental inmmunology , Cellular control mechanisms
- Description: Due to the diverse functions of Fc eRII, such as its roles in cellular adhesion, growth and differentiation of B and T lymphocytes, rescue of B cells from apoptosis and release of cytotoxic mediators, it is clear why it is believed to be a central molecule in allergic response. Because of its important role in the regulation of IgE production, FceRII may be the primary cause of certain allergic conditions. This study attempted to express and purify a recombinant human soluble FceRII to test its effect on a B-lymphoblastoid (RPMI 8866) and a monocytic (U937) cell line. The protein was expressed in Escherichia coli inclusion bodies, before being refolded and purified in a single gel chromatography step. This pure protein was then tested for biological activity by testing its IgE binding func tion. Once proven functional, it was used to test its effect on the cell lines at three concentrations for its apoptotic rescue properties and its cytokine effects. The recombinant protein did not seem to have any significant effect on the apoptotic rescue of either cell line. While the recombinant sFceRII appeared to have a slight effect on the stimulation of IL-1ß and TNFa in the RPMI 8866 cells, there was no apparent effect on the production of NF?B. In U937 cells, the protein did not seem to have any effect on the stimulation of IL-1ß, TNFa or NF?B. However, the cytokine effects of the recombinant protein were tested on isolated PBMCs from a healthy individual and a hyper-IgE syndrome patient. The recombinant protein was able to stimulate the production of cytokines in both individuals’ PBMCs, proving that it has the same effect as the natural protein. The upregulation of these cytokines indicates that the recombinant protein is able to stimulate the immune system. Therefore, this recombinant soluble FceRII protein could possibly be used for immune therapy.
- Full Text:
- Date Issued: 2003
- Authors: Daniels, Brodie Belinda
- Date: 2003
- Subjects: Developmental inmmunology , Cellular control mechanisms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11084 , http://hdl.handle.net/10948/322 , Developmental inmmunology , Cellular control mechanisms
- Description: Due to the diverse functions of Fc eRII, such as its roles in cellular adhesion, growth and differentiation of B and T lymphocytes, rescue of B cells from apoptosis and release of cytotoxic mediators, it is clear why it is believed to be a central molecule in allergic response. Because of its important role in the regulation of IgE production, FceRII may be the primary cause of certain allergic conditions. This study attempted to express and purify a recombinant human soluble FceRII to test its effect on a B-lymphoblastoid (RPMI 8866) and a monocytic (U937) cell line. The protein was expressed in Escherichia coli inclusion bodies, before being refolded and purified in a single gel chromatography step. This pure protein was then tested for biological activity by testing its IgE binding func tion. Once proven functional, it was used to test its effect on the cell lines at three concentrations for its apoptotic rescue properties and its cytokine effects. The recombinant protein did not seem to have any significant effect on the apoptotic rescue of either cell line. While the recombinant sFceRII appeared to have a slight effect on the stimulation of IL-1ß and TNFa in the RPMI 8866 cells, there was no apparent effect on the production of NF?B. In U937 cells, the protein did not seem to have any effect on the stimulation of IL-1ß, TNFa or NF?B. However, the cytokine effects of the recombinant protein were tested on isolated PBMCs from a healthy individual and a hyper-IgE syndrome patient. The recombinant protein was able to stimulate the production of cytokines in both individuals’ PBMCs, proving that it has the same effect as the natural protein. The upregulation of these cytokines indicates that the recombinant protein is able to stimulate the immune system. Therefore, this recombinant soluble FceRII protein could possibly be used for immune therapy.
- Full Text:
- Date Issued: 2003
The establishment of a virus free laboratory colony of Cryptophlebia leucotreta (False Codling Moth) and characterisation of Cryptophlebia leucotreta Granulovirus (CrleGV) genes
- Authors: Ludewig, Michael Hans
- Date: 2003
- Subjects: Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , DNA viruses , Agricultural pests -- Biological control , Baculoviruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3957 , http://hdl.handle.net/10962/d1004016 , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , DNA viruses , Agricultural pests -- Biological control , Baculoviruses
- Description: Cryptophlebia leucotreta is an economically important agricultural pest throughout Sub-Saharan Africa. CrleGV has been considered as an alternative to chemical control of this pest due to its host specificity and innocuous nature towards vertebrates. A CrleGV free laboratory colony of C. leucotreta would be useful for the isolation of genotypically pure strains of the CrleGV and for virulence comparisons between isolates. It is preferable to have a full characterisation of CrleGV prior to its registration and release into the environment as a biopesticide. A laboratory colony of C. leucotreta, set up at Rhodes University, containing a low level of infection indicated that CrleGV is vertically transmitted. To establish a virus free laboratory colony of C. leucotreta, a solution of 3.5% sodium hypochlorite and 1% Tween 20 was used to surface decontaminate C. leucotreta eggs for removal of transovum CrleGV from the laboratory colony. No apparent infection by CrleGV was induced by subjecting larvae to stress. PCR of DNA extracted from larvae using CTAB failed to detect virus in the laboratory colony. This detection protocol was able to detect down to 60 fg (480 genome copies of CrleGV). The possibility of low-level virus remaining in the colony requires monitoring of genotypic purity of virus manipulated in the colony. Sequencing of Bam HI/KpnI fragments produced a preliminary sequence of the granulin region of CrleGV. This preliminary sequence supports the trend that the gene organisation of the granulin region of the granuloviruses infecting the family Tortricidae is conserved.
- Full Text:
- Date Issued: 2003
- Authors: Ludewig, Michael Hans
- Date: 2003
- Subjects: Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , DNA viruses , Agricultural pests -- Biological control , Baculoviruses
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3957 , http://hdl.handle.net/10962/d1004016 , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Control , Pests -- Biological control , DNA viruses , Agricultural pests -- Biological control , Baculoviruses
- Description: Cryptophlebia leucotreta is an economically important agricultural pest throughout Sub-Saharan Africa. CrleGV has been considered as an alternative to chemical control of this pest due to its host specificity and innocuous nature towards vertebrates. A CrleGV free laboratory colony of C. leucotreta would be useful for the isolation of genotypically pure strains of the CrleGV and for virulence comparisons between isolates. It is preferable to have a full characterisation of CrleGV prior to its registration and release into the environment as a biopesticide. A laboratory colony of C. leucotreta, set up at Rhodes University, containing a low level of infection indicated that CrleGV is vertically transmitted. To establish a virus free laboratory colony of C. leucotreta, a solution of 3.5% sodium hypochlorite and 1% Tween 20 was used to surface decontaminate C. leucotreta eggs for removal of transovum CrleGV from the laboratory colony. No apparent infection by CrleGV was induced by subjecting larvae to stress. PCR of DNA extracted from larvae using CTAB failed to detect virus in the laboratory colony. This detection protocol was able to detect down to 60 fg (480 genome copies of CrleGV). The possibility of low-level virus remaining in the colony requires monitoring of genotypic purity of virus manipulated in the colony. Sequencing of Bam HI/KpnI fragments produced a preliminary sequence of the granulin region of CrleGV. This preliminary sequence supports the trend that the gene organisation of the granulin region of the granuloviruses infecting the family Tortricidae is conserved.
- Full Text:
- Date Issued: 2003
The hydrolysis of primary sewage sludge under biosulphidogenic conditions
- Molwantwa, Jennifer Balatedi
- Authors: Molwantwa, Jennifer Balatedi
- Date: 2003
- Subjects: Sewage sludge , Hydrolysis , Sewage -- Purification -- Activated sludge process
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3961 , http://hdl.handle.net/10962/d1004020 , Sewage sludge , Hydrolysis , Sewage -- Purification -- Activated sludge process
- Description: The potential for using readily available and cost-effective complex carbon sources such as primary sewage sludge for a range of environmental remediation processes, including biological sulphate reduction, biological nutrient removal and the bioremediation of acid mine drainage, has been constrained by the slow rate of solubilization and low yield of soluble products, which drive the above mentioned processes. Previous work conducted by the Environmental Biotechnology Group at Rhodes University indicated that the degradation of primary sewage sludge was enhanced under sulphate reducing conditions. This was proven in both laboratory and pilot-scale (Reciprocating Sludge Bed Reactor) systems, where the particulate matter accumulated in the sludge bed and the molecules in smaller flocs were rapidly solubilized. The current study was aimed at investigating in more detail the factors that govern the enhanced hydrolysis under sulphate reducing conditions, and to develop a descriptive model to explain the underlying mechanism involved. The solubilization of primary sewage sludge under sulphate reducing conditions was conducted in controlled flask studies and previously reported findings of enhanced hydrolysis were confirmed. The maximum percentage solubilization obtained in this study was 31% and 63% for the methanogenic and sulphidogenic systems respectively, and this was achieved over a period of 10 days. A rate of reducing sugar production and complex molecule breakdown of 51 mg. L⁻¹.hr⁻¹ and 167 mg.L⁻¹.hr⁻¹ was observed for the methanogenic and sulphidogenic systems respectively. The flask studies revealed that during hydrolysis of primary sewage sludge under sulphidogenic conditions there was enhanced production of soluble products, specifically carbohydrates (reducing sugars) and volatile fatty acids, compared to methanogenic conditions. The rate at which these products were utilized was also found to be more rapid under sulphidogenic as compared to methanogenic conditions. A study of the distribution of volatile fatty acids indicated that acetate was utilized preferentially in the methanogenic system, and that propionate, butyrate and valerate accumulated with time. The converse was found to occur in the sulphidogenic system. The descriptive model developed from the results of this study was based on the fact that a consortium of bacteria, composed of hydrolytic, acidogenic and acetogenic species, carries out the solubilization of complex carbon sources. Furthermore, it is essential that equilibrium between product formation and utilization is maintained, and that accumulation of soluble end products impacts negatively on the rate of the hydrolysis step. It is therefore proposed that the relatively poor utilization of VFA and reducing sugars in the methanogenic system activates a negative feedback inhibition on the hydrolytic and/ or acidogenic step. This inhibition is reduced in the sulphidogenic system where the utilization of end products is higher.
- Full Text:
- Date Issued: 2003
- Authors: Molwantwa, Jennifer Balatedi
- Date: 2003
- Subjects: Sewage sludge , Hydrolysis , Sewage -- Purification -- Activated sludge process
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3961 , http://hdl.handle.net/10962/d1004020 , Sewage sludge , Hydrolysis , Sewage -- Purification -- Activated sludge process
- Description: The potential for using readily available and cost-effective complex carbon sources such as primary sewage sludge for a range of environmental remediation processes, including biological sulphate reduction, biological nutrient removal and the bioremediation of acid mine drainage, has been constrained by the slow rate of solubilization and low yield of soluble products, which drive the above mentioned processes. Previous work conducted by the Environmental Biotechnology Group at Rhodes University indicated that the degradation of primary sewage sludge was enhanced under sulphate reducing conditions. This was proven in both laboratory and pilot-scale (Reciprocating Sludge Bed Reactor) systems, where the particulate matter accumulated in the sludge bed and the molecules in smaller flocs were rapidly solubilized. The current study was aimed at investigating in more detail the factors that govern the enhanced hydrolysis under sulphate reducing conditions, and to develop a descriptive model to explain the underlying mechanism involved. The solubilization of primary sewage sludge under sulphate reducing conditions was conducted in controlled flask studies and previously reported findings of enhanced hydrolysis were confirmed. The maximum percentage solubilization obtained in this study was 31% and 63% for the methanogenic and sulphidogenic systems respectively, and this was achieved over a period of 10 days. A rate of reducing sugar production and complex molecule breakdown of 51 mg. L⁻¹.hr⁻¹ and 167 mg.L⁻¹.hr⁻¹ was observed for the methanogenic and sulphidogenic systems respectively. The flask studies revealed that during hydrolysis of primary sewage sludge under sulphidogenic conditions there was enhanced production of soluble products, specifically carbohydrates (reducing sugars) and volatile fatty acids, compared to methanogenic conditions. The rate at which these products were utilized was also found to be more rapid under sulphidogenic as compared to methanogenic conditions. A study of the distribution of volatile fatty acids indicated that acetate was utilized preferentially in the methanogenic system, and that propionate, butyrate and valerate accumulated with time. The converse was found to occur in the sulphidogenic system. The descriptive model developed from the results of this study was based on the fact that a consortium of bacteria, composed of hydrolytic, acidogenic and acetogenic species, carries out the solubilization of complex carbon sources. Furthermore, it is essential that equilibrium between product formation and utilization is maintained, and that accumulation of soluble end products impacts negatively on the rate of the hydrolysis step. It is therefore proposed that the relatively poor utilization of VFA and reducing sugars in the methanogenic system activates a negative feedback inhibition on the hydrolytic and/ or acidogenic step. This inhibition is reduced in the sulphidogenic system where the utilization of end products is higher.
- Full Text:
- Date Issued: 2003
The potential of abalone stock enhancement in the Eastern Cape Province of South Africa
- Authors: Godfrey, Brian Peter
- Date: 2003
- Subjects: Abalones -- South Africa -- Eastern Cape , Abalone culture , Abalone fisheries -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5312 , http://hdl.handle.net/10962/d1005157 , Abalones -- South Africa -- Eastern Cape , Abalone culture , Abalone fisheries -- South Africa -- Eastern Cape
- Description: The largest abalone in South Africa, the perlemoen, Haliotis midae, occurs along approximately two-thirds of the country's coastline, but has only been the target of an extensive commercial fishery in the south-western part of South Africa. Large-scale illegal fishing has however proliferated throughout its entire range over the last 10–15 years, which has had serious effects on stock abundance and once productive populations are facing economic collapse. Abalone stock enhancement has been put forward as an addition or alternative to traditional fisheries management practices, which can potentially rehabilitate overfished abalone populations and enhance natural production. The aim of this project was to investigate the potential of abalone stock enhancement for managing an area in the Eastern Cape Province, which was being subjected to intense illegal fishing pressure. A research approach was adopted to investigate the scale and effects of this poaching and to investigate the survival of artificially cultured abalone seed in the natural environment. A model of a commercial-scale ranching operation was investigated to assess the economic feasibility of such a scheme. Analysis of poaching cases and research samples from Cape Recife indicated high levels of fishing effort that appeared to be causing the observed declines in emergent abalone abundance and average size. Poaching cases from Cape Recife contributed 32% of the total number of cases of known origin in the Eastern Cape Province from 1998–2002, with the majority of the cases (82%) originating from within the Port Elizabeth metropole. There was an exponential increase in the number of poaching cases in the Eastern Cape Province (r²=0.967) and Port Elizabeth over this period but actual annual total catch stabilized, particularly at Cape Recife, where estimates of CPUE declined significantly from 2000–2002 (p<0.001). The annual proportion of emergent abalone under the MLS from Cape Recife was always >85% in confiscations and research collections, and did not change significantly over the period of examination. Comparison of illegal catches with an adjacent site indicated that the emergent abalone population at Cape Recife had a significantly higher proportion of undersized emergent animals (p<0.001) and they were significantly smaller than the abalone from the closest site, Noordhoek, and other areas in Port Elizabeth from 2000–2002 (p<0.001). The apparent declines in emergent abalone abundance indicated by the poaching data were corroborated by sampling of emergent abalone abundance at Cape Recife. Numbers of abalone declined significantly from 125.6 to 53.8 per 20min count (p<0.001), from April 1998–October 2001 and density declined from 1.3 to 0.8m⁻² over a similar period (p<0.001). Juvenile density did not change over this period, although there were significant differences in density observed between two different habitats (p<0.001). Initial releases of cultured juvenile abalone showed that they could be distinguished from their wild counterparts for at least a year after release, by their different shell colouration. Short-term, small-scale trials (7–10 days) using animals between 17 and 30mm SL had mean survival rates of 64–82% (mean 70.4%) and the effect of size on survival was not significant in most cases, although the power to detect differences was low. Attempts to measure the effect of habitat on survival were not conclusive, although refuges under sea urchins appeared to be favoured by both seed and wild abalone, although urchins were not an absolute requirement for survival. Similar medium-term trials (31–74 days) in sheltered sites yielded mean returns of 53.1% using 25mm SL animals and similar trials in a more exposed area had more variable survival rates of between 18.4 and 73.6%, after 25–27 days. A comparison between careful hand-seeding and surface-scattering seed release methods in the open-ocean habitat showed no significant differences in survival rate after 41 days. Larger seed survived significantly better than the smaller seed when scattered on the surface (p<0.0001) and the smaller seed survived significantly better when seeded carefully by hand onto the substrate (p<0.028). Further medium-term releases of large numbers of seed abalone, released using the surface-scattering method in open-ocean habitat, gave mean survival rates of 32.8% over periods of 83–114 days. Assessment of a seeding trial using release modules to seed juvenile animals in the open-ocean was hampered by poor sea conditions and difficult to search substrates, and a mean recovery rate of 3.1% was obtained for the sites that were sampled. Movement of seed was low in the more sheltered sites, and also appeared to be affected by the amount of available habitat. Growth of seed was measured using changes in shell colouration and there were significant differences between areas. An average growth of 1.6mm.month⁻¹ shell length was calculated for all areas. The potential for commercial scale abalone ranching to be used to enhance a territorial user right fishery was investigated using a model of economic feasibility. Internal rates of return of 30.3 and 36.9% were obtained from two harvest regimes using different harvest sizes. There was a high degree of risk associated with these figures owing to a lack of consistent seed survival rate estimates, and the input parameters, which are subject to variation, showed a significant effect on profitability. The operation of this type of ranching scheme is probably not economically feasible as a stand-alone operation but could probably be operated effectively in conjunction with an existing abalone farm. By adding a small wild catch component the profitability of a ranching scheme could be significantly improved. The results of the present study indicate that high levels of poaching at Cape Recife have led to declines in emergent abalone abundance, which will probably lead to stock collapse in the near future. This implies that fisheries managers have failed to fulfil the provisions of fisheries policy in South Africa. The present results from seeding trials show that cultured juveniles can survive and make a contribution to overall stock abundance. Furthermore, while there are obstacles to economic feasibility, commercial ranching has the potential to be a valuable addition to current abalone management strategy.
- Full Text:
- Date Issued: 2003
- Authors: Godfrey, Brian Peter
- Date: 2003
- Subjects: Abalones -- South Africa -- Eastern Cape , Abalone culture , Abalone fisheries -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5312 , http://hdl.handle.net/10962/d1005157 , Abalones -- South Africa -- Eastern Cape , Abalone culture , Abalone fisheries -- South Africa -- Eastern Cape
- Description: The largest abalone in South Africa, the perlemoen, Haliotis midae, occurs along approximately two-thirds of the country's coastline, but has only been the target of an extensive commercial fishery in the south-western part of South Africa. Large-scale illegal fishing has however proliferated throughout its entire range over the last 10–15 years, which has had serious effects on stock abundance and once productive populations are facing economic collapse. Abalone stock enhancement has been put forward as an addition or alternative to traditional fisheries management practices, which can potentially rehabilitate overfished abalone populations and enhance natural production. The aim of this project was to investigate the potential of abalone stock enhancement for managing an area in the Eastern Cape Province, which was being subjected to intense illegal fishing pressure. A research approach was adopted to investigate the scale and effects of this poaching and to investigate the survival of artificially cultured abalone seed in the natural environment. A model of a commercial-scale ranching operation was investigated to assess the economic feasibility of such a scheme. Analysis of poaching cases and research samples from Cape Recife indicated high levels of fishing effort that appeared to be causing the observed declines in emergent abalone abundance and average size. Poaching cases from Cape Recife contributed 32% of the total number of cases of known origin in the Eastern Cape Province from 1998–2002, with the majority of the cases (82%) originating from within the Port Elizabeth metropole. There was an exponential increase in the number of poaching cases in the Eastern Cape Province (r²=0.967) and Port Elizabeth over this period but actual annual total catch stabilized, particularly at Cape Recife, where estimates of CPUE declined significantly from 2000–2002 (p<0.001). The annual proportion of emergent abalone under the MLS from Cape Recife was always >85% in confiscations and research collections, and did not change significantly over the period of examination. Comparison of illegal catches with an adjacent site indicated that the emergent abalone population at Cape Recife had a significantly higher proportion of undersized emergent animals (p<0.001) and they were significantly smaller than the abalone from the closest site, Noordhoek, and other areas in Port Elizabeth from 2000–2002 (p<0.001). The apparent declines in emergent abalone abundance indicated by the poaching data were corroborated by sampling of emergent abalone abundance at Cape Recife. Numbers of abalone declined significantly from 125.6 to 53.8 per 20min count (p<0.001), from April 1998–October 2001 and density declined from 1.3 to 0.8m⁻² over a similar period (p<0.001). Juvenile density did not change over this period, although there were significant differences in density observed between two different habitats (p<0.001). Initial releases of cultured juvenile abalone showed that they could be distinguished from their wild counterparts for at least a year after release, by their different shell colouration. Short-term, small-scale trials (7–10 days) using animals between 17 and 30mm SL had mean survival rates of 64–82% (mean 70.4%) and the effect of size on survival was not significant in most cases, although the power to detect differences was low. Attempts to measure the effect of habitat on survival were not conclusive, although refuges under sea urchins appeared to be favoured by both seed and wild abalone, although urchins were not an absolute requirement for survival. Similar medium-term trials (31–74 days) in sheltered sites yielded mean returns of 53.1% using 25mm SL animals and similar trials in a more exposed area had more variable survival rates of between 18.4 and 73.6%, after 25–27 days. A comparison between careful hand-seeding and surface-scattering seed release methods in the open-ocean habitat showed no significant differences in survival rate after 41 days. Larger seed survived significantly better than the smaller seed when scattered on the surface (p<0.0001) and the smaller seed survived significantly better when seeded carefully by hand onto the substrate (p<0.028). Further medium-term releases of large numbers of seed abalone, released using the surface-scattering method in open-ocean habitat, gave mean survival rates of 32.8% over periods of 83–114 days. Assessment of a seeding trial using release modules to seed juvenile animals in the open-ocean was hampered by poor sea conditions and difficult to search substrates, and a mean recovery rate of 3.1% was obtained for the sites that were sampled. Movement of seed was low in the more sheltered sites, and also appeared to be affected by the amount of available habitat. Growth of seed was measured using changes in shell colouration and there were significant differences between areas. An average growth of 1.6mm.month⁻¹ shell length was calculated for all areas. The potential for commercial scale abalone ranching to be used to enhance a territorial user right fishery was investigated using a model of economic feasibility. Internal rates of return of 30.3 and 36.9% were obtained from two harvest regimes using different harvest sizes. There was a high degree of risk associated with these figures owing to a lack of consistent seed survival rate estimates, and the input parameters, which are subject to variation, showed a significant effect on profitability. The operation of this type of ranching scheme is probably not economically feasible as a stand-alone operation but could probably be operated effectively in conjunction with an existing abalone farm. By adding a small wild catch component the profitability of a ranching scheme could be significantly improved. The results of the present study indicate that high levels of poaching at Cape Recife have led to declines in emergent abalone abundance, which will probably lead to stock collapse in the near future. This implies that fisheries managers have failed to fulfil the provisions of fisheries policy in South Africa. The present results from seeding trials show that cultured juveniles can survive and make a contribution to overall stock abundance. Furthermore, while there are obstacles to economic feasibility, commercial ranching has the potential to be a valuable addition to current abalone management strategy.
- Full Text:
- Date Issued: 2003
The specification and design of a prototype 2-D MPEG-4 authoring tool
- Authors: Viljoen, Deon Walter
- Date: 2003
- Subjects: MPEG (Video coding standard) , Digital video -- Standards , Multimedia systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11092 , http://hdl.handle.net/10948/d1015741 , MPEG (Video coding standard) , Digital video -- Standards , Multimedia systems
- Description: The purpose of this project was the specification, design and implementation of a prototype 2-D MPEG-4 authoring tool. A literature study was conducted of the MPEG-4 standard and multimedia authoring tools to determine the specification and design of a prototype 2- D MPEG-4 authoring tool. The specification and design was used as a basis for the implementation of a prototype 2-D MPEG-4 authoring tool that complies with the Complete 2-D Scene Graph Profile. The need for research into MPEG-4 authoring tools arose from the reported lack of knowledge of the MPEG-4 standard and the limited implementations of MPEG-4 authoring tools available to content authors. In order for MPEG-4 to reach its full potential, it will require authoring tools and content players that satisfy the needs of its users. The theoretical component of this dissertation included a literature study of the MPEG-4 standard and an investigation of relevant multimedia authoring systems. MPEG-4 was introduced as a standard that allows for the creation and streaming of interactive multimedia content at variable bit rates over high and low bandwidth connections. The requirements for the prototype 2-D MPEG-4 authoring system were documented and a prototype system satisfying the requirements was designed, implemented and evaluated. The evaluation of the prototype system showed that the system successfully satisfied all its requirements and that it provides the user with an easy to use and intuitive authoring tool. MPEG-4 has the potential to satisfy the increasing demand for innovative multimedia content on low bandwidth networks, including the Internet and mobile networks, as well as the need expressed by users to interact with multimedia content. This dissertation makes an important contribution to the understanding of the MPEG-4 standard, its functionality and the design of a 2-D MPEG-4 Authoring tool. Keywords: MPEG-4; MPEG-4 authoring; Binary Format for Scenes.
- Full Text:
- Date Issued: 2003
- Authors: Viljoen, Deon Walter
- Date: 2003
- Subjects: MPEG (Video coding standard) , Digital video -- Standards , Multimedia systems
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11092 , http://hdl.handle.net/10948/d1015741 , MPEG (Video coding standard) , Digital video -- Standards , Multimedia systems
- Description: The purpose of this project was the specification, design and implementation of a prototype 2-D MPEG-4 authoring tool. A literature study was conducted of the MPEG-4 standard and multimedia authoring tools to determine the specification and design of a prototype 2- D MPEG-4 authoring tool. The specification and design was used as a basis for the implementation of a prototype 2-D MPEG-4 authoring tool that complies with the Complete 2-D Scene Graph Profile. The need for research into MPEG-4 authoring tools arose from the reported lack of knowledge of the MPEG-4 standard and the limited implementations of MPEG-4 authoring tools available to content authors. In order for MPEG-4 to reach its full potential, it will require authoring tools and content players that satisfy the needs of its users. The theoretical component of this dissertation included a literature study of the MPEG-4 standard and an investigation of relevant multimedia authoring systems. MPEG-4 was introduced as a standard that allows for the creation and streaming of interactive multimedia content at variable bit rates over high and low bandwidth connections. The requirements for the prototype 2-D MPEG-4 authoring system were documented and a prototype system satisfying the requirements was designed, implemented and evaluated. The evaluation of the prototype system showed that the system successfully satisfied all its requirements and that it provides the user with an easy to use and intuitive authoring tool. MPEG-4 has the potential to satisfy the increasing demand for innovative multimedia content on low bandwidth networks, including the Internet and mobile networks, as well as the need expressed by users to interact with multimedia content. This dissertation makes an important contribution to the understanding of the MPEG-4 standard, its functionality and the design of a 2-D MPEG-4 Authoring tool. Keywords: MPEG-4; MPEG-4 authoring; Binary Format for Scenes.
- Full Text:
- Date Issued: 2003
The structure of ant communities and their impact on soil-pupating pests in citrus orchards in the Grahamstown area of the Eastern Cape
- Authors: Bownes, Angela
- Date: 2003
- Subjects: Ants -- South Africa -- Eastern Cape , Pests -- Control -- South Africa , Homoptera -- Control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5775 , http://hdl.handle.net/10962/d1005463 , Ants -- South Africa -- Eastern Cape , Pests -- Control -- South Africa , Homoptera -- Control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- South Africa -- Eastern Cape
- Description: Two ant species, Pheidole megacephala (Fabricius) and Anoplolepis custodiens (Smith) reach pest status in citrus orchards through precipitating outbreaks of homopterous pests. However, predacious ants, including these two ant species, play an important role in pest suppression in agroecosystems and are therefore beneficial to these systems. If A. custodiens and P. megacephala are important natural control agents in citrus, using ant bands to break the mutualism between the ants and the Homoptera as a method of ant control is preferable to poisoning. Ant communities were sampled by pitfall trapping in three experimental subunits of 2-, 4-, 15- and 30-year-old citrus orchards, in the Grahamstown area of the Eastern Cape. In one subunit in each orchard, populations of P. megacephala and A. custodiens were suppressed by poison applications. In a second subunit, trees were banded with trunk barriers so that ants were prevented from foraging in the trees and a third subunit served as the untreated control. Bait pupae of bollworm, false codling moth and fruit fly were planted in bait trays in all of the subunits to investigate predation on these citrus pests in the relative absence of predacious ants and where they were excluded from the trees. Pheidole megacephala dominated exclusively in all of the plots. Community composition did not change dramatically with increasing age of the trees, but species diversity and species abundance did. Rank-abundance curves showed that community diversity was highest in the 2-year-old plots and lowest in the 30-year-old plots. The Simpson and Shannon-Wiener diversity indices and their evenness measures indicated that diversity and equitability were highest in the poisoned subunits and lowest in the banded subunits. Principle component analysis revealed that the poisoned subunits were similar and distinct in species composition, that there was significant monthly variation in species composition and that community stability increases with an increase in orchard age. The presence of P. megacephala was significantly negatively correlated (rs = -0.293; p < 0.001) with pest pupal survival. Pupal survival was significantly higher for bollworm (p < 0.001), FCM (p < 0.001) and fruit fly (p < 0.001) in the poisoned subunits, than in the banded and control subunits. There was a general trend for survivorship to increase with an increase in the age of the trees. A significant difference (p < 0.001) was found between the months in which the trials were carried out. Pupal survival was significantly lower (p < 0.001) for FCM than for bollworm and fruit fly. In citrus orchards, ant communities are organised by ecological processes and interactions and are influenced by methods of ant control. Ant bands are preferable to poisoning as a method of ant control, so that beneficial species are left on the ground to prey on pests that pupate in the soil. Maintaining high ant species diversity in citrus orchards would be beneficial as predation on the pupae was more effective where ant species diversity was higher.
- Full Text:
- Date Issued: 2003
- Authors: Bownes, Angela
- Date: 2003
- Subjects: Ants -- South Africa -- Eastern Cape , Pests -- Control -- South Africa , Homoptera -- Control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5775 , http://hdl.handle.net/10962/d1005463 , Ants -- South Africa -- Eastern Cape , Pests -- Control -- South Africa , Homoptera -- Control -- South Africa -- Eastern Cape , Citrus -- Diseases and pests -- South Africa -- Eastern Cape
- Description: Two ant species, Pheidole megacephala (Fabricius) and Anoplolepis custodiens (Smith) reach pest status in citrus orchards through precipitating outbreaks of homopterous pests. However, predacious ants, including these two ant species, play an important role in pest suppression in agroecosystems and are therefore beneficial to these systems. If A. custodiens and P. megacephala are important natural control agents in citrus, using ant bands to break the mutualism between the ants and the Homoptera as a method of ant control is preferable to poisoning. Ant communities were sampled by pitfall trapping in three experimental subunits of 2-, 4-, 15- and 30-year-old citrus orchards, in the Grahamstown area of the Eastern Cape. In one subunit in each orchard, populations of P. megacephala and A. custodiens were suppressed by poison applications. In a second subunit, trees were banded with trunk barriers so that ants were prevented from foraging in the trees and a third subunit served as the untreated control. Bait pupae of bollworm, false codling moth and fruit fly were planted in bait trays in all of the subunits to investigate predation on these citrus pests in the relative absence of predacious ants and where they were excluded from the trees. Pheidole megacephala dominated exclusively in all of the plots. Community composition did not change dramatically with increasing age of the trees, but species diversity and species abundance did. Rank-abundance curves showed that community diversity was highest in the 2-year-old plots and lowest in the 30-year-old plots. The Simpson and Shannon-Wiener diversity indices and their evenness measures indicated that diversity and equitability were highest in the poisoned subunits and lowest in the banded subunits. Principle component analysis revealed that the poisoned subunits were similar and distinct in species composition, that there was significant monthly variation in species composition and that community stability increases with an increase in orchard age. The presence of P. megacephala was significantly negatively correlated (rs = -0.293; p < 0.001) with pest pupal survival. Pupal survival was significantly higher for bollworm (p < 0.001), FCM (p < 0.001) and fruit fly (p < 0.001) in the poisoned subunits, than in the banded and control subunits. There was a general trend for survivorship to increase with an increase in the age of the trees. A significant difference (p < 0.001) was found between the months in which the trials were carried out. Pupal survival was significantly lower (p < 0.001) for FCM than for bollworm and fruit fly. In citrus orchards, ant communities are organised by ecological processes and interactions and are influenced by methods of ant control. Ant bands are preferable to poisoning as a method of ant control, so that beneficial species are left on the ground to prey on pests that pupate in the soil. Maintaining high ant species diversity in citrus orchards would be beneficial as predation on the pupae was more effective where ant species diversity was higher.
- Full Text:
- Date Issued: 2003
The suitability of Alagoasa extrema Jacoby (Coleoptera: Chrysomelidae: Alticinae), as a biological control agent for Lantana camara L. in South Africa
- Authors: Williams, Hester Elizabeth
- Date: 2003
- Subjects: Lantana camara , Lantana camara -- South Africa , Biological pest control agents -- South Africa , Chrysomelidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5783 , http://hdl.handle.net/10962/d1005471 , Lantana camara , Lantana camara -- South Africa , Biological pest control agents -- South Africa , Chrysomelidae
- Description: Lantana camara Linnaeus (Verbenaceae), commonly known as lantana, is a highly invasive weed in many parts of the world. In South Africa it is naturalized in several provinces where it invades pastures, riverbanks, mountain slopes and valleys and commercial and natural forests, forming dense, impenetrable thickets. Chemical and mechanical control methods are expensive, labour intensive and provide only temporary relief as cleared areas are rapidly reinfested by seedlings and coppice growth. A biological control programme was initiated in South Africa in the 1960s, but despite the establishment of 11 agent species, it was considered to have had limited success. Several factors are thought to restrict the impact of the biocontrol agents. Firstly, L. camara occurs in a range of climatic regions, some of which are unsuitable for the establishment of agent species of tropical and subtropical origin. Secondly, L. camara is the result of hybridization between several Lantana species, forming a complex of hybridized and hybridizing varieties in the field, which match none of the Lantana species in the region of origin. This causes partial insect-host incompatibility, displayed as varietal preference. Thirdly, parasitism appears to have significantly reduced the effectiveness of several natural enemies. In spite of all these constraints, biological control has reduced invasion by L. camara by 26%. However, the weed is still very damaging and additional natural enemies are required to reduce infestations further. A flea-beetle species, Alagoasa extrema Jacoby (Coleoptera: Chrysomelidae), was collected from several sites in the humid subtropical and tropical regions of Mexico, and imported into quarantine in South Africa and studied as a potential biocontrol agent for L. camara. Favourable biological characteristics of this beetle included long-lived adults, several overlapping generations per year, and high adult and larval feeding rates. Observations from the insect’s native range and studies in South Africa suggest that A. extrema would probably be more suited to the subtropical, rather than the temperate areas in South Africa. Laboratory impact studies indicated that feeding damage by A. extrema larvae, over a period spanning the larval stage (16 to 20 days), reduced the above-ground biomass of L. camara plants by up to 29%. Higher larval populations resulted in a higher reduction of biomass. Varietal preference and suitability studies indicated that A. extrema exhibits a degree of varietal preference under laboratory conditions, with one of the white pink L. camara varieties proving the most suitable host. This variety is one of the most damaging varieties in South Africa and is particularly widespread in Mpumalanga Province. Although A. extrema proved to be damaging to L. camara, laboratory host range trials showed it to be an oligophagous species, capable of feeding and developing on several non-target species, especially two native Lippia species (Verbenaceae). The host suitability of these species was marginally lower than that of L. camara and the potential risk to these indigenous species was deemed to be too high to warrant release. It was therefore recommended that A. extrema not be considered for release in South Africa.
- Full Text:
- Date Issued: 2003
- Authors: Williams, Hester Elizabeth
- Date: 2003
- Subjects: Lantana camara , Lantana camara -- South Africa , Biological pest control agents -- South Africa , Chrysomelidae
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5783 , http://hdl.handle.net/10962/d1005471 , Lantana camara , Lantana camara -- South Africa , Biological pest control agents -- South Africa , Chrysomelidae
- Description: Lantana camara Linnaeus (Verbenaceae), commonly known as lantana, is a highly invasive weed in many parts of the world. In South Africa it is naturalized in several provinces where it invades pastures, riverbanks, mountain slopes and valleys and commercial and natural forests, forming dense, impenetrable thickets. Chemical and mechanical control methods are expensive, labour intensive and provide only temporary relief as cleared areas are rapidly reinfested by seedlings and coppice growth. A biological control programme was initiated in South Africa in the 1960s, but despite the establishment of 11 agent species, it was considered to have had limited success. Several factors are thought to restrict the impact of the biocontrol agents. Firstly, L. camara occurs in a range of climatic regions, some of which are unsuitable for the establishment of agent species of tropical and subtropical origin. Secondly, L. camara is the result of hybridization between several Lantana species, forming a complex of hybridized and hybridizing varieties in the field, which match none of the Lantana species in the region of origin. This causes partial insect-host incompatibility, displayed as varietal preference. Thirdly, parasitism appears to have significantly reduced the effectiveness of several natural enemies. In spite of all these constraints, biological control has reduced invasion by L. camara by 26%. However, the weed is still very damaging and additional natural enemies are required to reduce infestations further. A flea-beetle species, Alagoasa extrema Jacoby (Coleoptera: Chrysomelidae), was collected from several sites in the humid subtropical and tropical regions of Mexico, and imported into quarantine in South Africa and studied as a potential biocontrol agent for L. camara. Favourable biological characteristics of this beetle included long-lived adults, several overlapping generations per year, and high adult and larval feeding rates. Observations from the insect’s native range and studies in South Africa suggest that A. extrema would probably be more suited to the subtropical, rather than the temperate areas in South Africa. Laboratory impact studies indicated that feeding damage by A. extrema larvae, over a period spanning the larval stage (16 to 20 days), reduced the above-ground biomass of L. camara plants by up to 29%. Higher larval populations resulted in a higher reduction of biomass. Varietal preference and suitability studies indicated that A. extrema exhibits a degree of varietal preference under laboratory conditions, with one of the white pink L. camara varieties proving the most suitable host. This variety is one of the most damaging varieties in South Africa and is particularly widespread in Mpumalanga Province. Although A. extrema proved to be damaging to L. camara, laboratory host range trials showed it to be an oligophagous species, capable of feeding and developing on several non-target species, especially two native Lippia species (Verbenaceae). The host suitability of these species was marginally lower than that of L. camara and the potential risk to these indigenous species was deemed to be too high to warrant release. It was therefore recommended that A. extrema not be considered for release in South Africa.
- Full Text:
- Date Issued: 2003
Using E-learning to support IT education in a university environment a case study approach
- Authors: Taljaard, Marinda
- Date: 2003
- Subjects: Education, Higher -- South Africa -- Port Elizabeth -- Computer-assisted instruction , Internet in education , Information technology -- Study and teaching (Higher) -- South Africa -- Port Elizabeth , College teaching -- South Africa -- Port Elizabeth -- Computer network resources , University of Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11091 , http://hdl.handle.net/10948/d1015740 , Education, Higher -- South Africa -- Port Elizabeth -- Computer-assisted instruction , Internet in education , Information technology -- Study and teaching (Higher) -- South Africa -- Port Elizabeth , College teaching -- South Africa -- Port Elizabeth -- Computer network resources , University of Port Elizabeth
- Description: At the University of Port Elizabeth (UPE), the End User Computing course (EUC) acts as a service course for many departments. This implies that many students are forced by their curricula to register for this course. The ever-increasing numbers in EUC place a considerable load on existing human and physical resources. In lecture groups of 120 –160, students rarely get the attention they need, and the pace at which the content is delivered (too slow or too fast) may also inhibit the learning process. During an initial investigation into E-learning at UPE in 1999, a prototype virtual classroom was developed. There were, however, a number of problems with this prototype. Firstly, it was implemented using a number of different technologies, which made it difficult to extend and maintain. Secondly, it only addressed some aspects of an E-learning environment, which proved insufficient for the EUC course. In the existing EUC course at UPE, the students are already exposed to some E-learning concepts, as a section of their skills training component is handled by using multimedia software in a simulated environment. The objective of this project was to extend the E-learning component further to determine the advantages and disadvantages of using E-learning to support information technology (IT) education in a contact-university environment. This project included a literature search and survey of existing E-learning environments at other universities. This research was used to develop a draft framework for an E-learning environment. The framework was used to select a tool to create an E-learning environment at UPE. An experiment was designed using this E-learning environment to support two IT courses at different year levels. The results of the experiment were analysed using qualitative and quantitative methods to determine the impact of using E-learning to support IT education at UPE. The results of this research show that E-learning can be used to support IT education at UPE. More success, however, was achieved at postgraduate level than at first-year level. Making use of Elearning increased student satisfaction and promoted active learning, while providing benefits like convenience, communication, flexibility and scaffolding. We conclude, therefore, that E-learning can provide a flexible approach to IT education in a university environment in the future.
- Full Text:
- Date Issued: 2003
- Authors: Taljaard, Marinda
- Date: 2003
- Subjects: Education, Higher -- South Africa -- Port Elizabeth -- Computer-assisted instruction , Internet in education , Information technology -- Study and teaching (Higher) -- South Africa -- Port Elizabeth , College teaching -- South Africa -- Port Elizabeth -- Computer network resources , University of Port Elizabeth
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:11091 , http://hdl.handle.net/10948/d1015740 , Education, Higher -- South Africa -- Port Elizabeth -- Computer-assisted instruction , Internet in education , Information technology -- Study and teaching (Higher) -- South Africa -- Port Elizabeth , College teaching -- South Africa -- Port Elizabeth -- Computer network resources , University of Port Elizabeth
- Description: At the University of Port Elizabeth (UPE), the End User Computing course (EUC) acts as a service course for many departments. This implies that many students are forced by their curricula to register for this course. The ever-increasing numbers in EUC place a considerable load on existing human and physical resources. In lecture groups of 120 –160, students rarely get the attention they need, and the pace at which the content is delivered (too slow or too fast) may also inhibit the learning process. During an initial investigation into E-learning at UPE in 1999, a prototype virtual classroom was developed. There were, however, a number of problems with this prototype. Firstly, it was implemented using a number of different technologies, which made it difficult to extend and maintain. Secondly, it only addressed some aspects of an E-learning environment, which proved insufficient for the EUC course. In the existing EUC course at UPE, the students are already exposed to some E-learning concepts, as a section of their skills training component is handled by using multimedia software in a simulated environment. The objective of this project was to extend the E-learning component further to determine the advantages and disadvantages of using E-learning to support information technology (IT) education in a contact-university environment. This project included a literature search and survey of existing E-learning environments at other universities. This research was used to develop a draft framework for an E-learning environment. The framework was used to select a tool to create an E-learning environment at UPE. An experiment was designed using this E-learning environment to support two IT courses at different year levels. The results of the experiment were analysed using qualitative and quantitative methods to determine the impact of using E-learning to support IT education at UPE. The results of this research show that E-learning can be used to support IT education at UPE. More success, however, was achieved at postgraduate level than at first-year level. Making use of Elearning increased student satisfaction and promoted active learning, while providing benefits like convenience, communication, flexibility and scaffolding. We conclude, therefore, that E-learning can provide a flexible approach to IT education in a university environment in the future.
- Full Text:
- Date Issued: 2003