ATP mimics as glutamine synthetase inhibitors : an exploratory synthetic study
- Authors: Salisu, Sheriff Tomilola
- Date: 2008
- Subjects: Glutamine synthetase Tuberculosis -- Treatment Tuberculosis -- Chemotherapy Adenosine triphosphate Adenosine triphosphate -- Synthesis Drug development
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4408 , http://hdl.handle.net/10962/d1006715
- Description: Using a mechanism-based approach to drug discovery, efforts have been directed towards developing novel ATP mimics that can act as GS inhibitors. The purine-based systems, adenosine, adenine and allopurinol, were identified as possible scaffolds for potential ATP mimics, while various meta-disubstituted benzenoid compounds, 3-aminobenzonitrile, 3-aminophenol, resorcinol, 3-aminobenzyl alcohol, 3-hydroxybenzoic acid and 3-aminobenzoic acid have been explored as adenine analogues. These compounds were treated with different alkylating and acylating agents. Allylation of all the substrates was achieved using allyl bromide and N-9 alkylation of protected allopurinol was effected using a number of specially prepared Baylis-Hillman adducts. Acylation of the benzenoid precursors with chloroacetyl chloride, acetoxyacetyl chloride, acryloyl chloride and specially prepared 2,3,4,5,6-pentaacetylgluconoyl chloride afforded the corresponding mono- and /or diacylated products in varying yields (4-96%). Elaboration of the alkylated and acylated products has involved the reaction of hydroxy systems with diethyl chloro phosphate and chloro derivatives with triethyl phosphite in Arbuzov-type reactions to afford phosphorylated products. In all cases, products were fully characterized using 1- and 2-D NMR analysis and, where appropriate, high-resolution mass spectrometry. The application of Modgraph and ChemWindow NMR prediction programmes has been explored and the resulting data have been compared with experimental chemical shift assignments to confirm chemical structures and, in some cases, to establish the position of allylation or acylation. Experimental assignments were found to be generally comparable with the Modgraph data, but not always with the ChemWindow values. The docking of selected products in the 'active-site' of GS and their structural homology with ATP, both in their free and bound conformations have been studied using the ACCELERYS Cerius² platform. All the selected ATP mimics exhibit some form of interaction with the 'active-site' residues, and a number of them appear to be promising GS ligands.
- Full Text:
- Date Issued: 2008
- Authors: Salisu, Sheriff Tomilola
- Date: 2008
- Subjects: Glutamine synthetase Tuberculosis -- Treatment Tuberculosis -- Chemotherapy Adenosine triphosphate Adenosine triphosphate -- Synthesis Drug development
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4408 , http://hdl.handle.net/10962/d1006715
- Description: Using a mechanism-based approach to drug discovery, efforts have been directed towards developing novel ATP mimics that can act as GS inhibitors. The purine-based systems, adenosine, adenine and allopurinol, were identified as possible scaffolds for potential ATP mimics, while various meta-disubstituted benzenoid compounds, 3-aminobenzonitrile, 3-aminophenol, resorcinol, 3-aminobenzyl alcohol, 3-hydroxybenzoic acid and 3-aminobenzoic acid have been explored as adenine analogues. These compounds were treated with different alkylating and acylating agents. Allylation of all the substrates was achieved using allyl bromide and N-9 alkylation of protected allopurinol was effected using a number of specially prepared Baylis-Hillman adducts. Acylation of the benzenoid precursors with chloroacetyl chloride, acetoxyacetyl chloride, acryloyl chloride and specially prepared 2,3,4,5,6-pentaacetylgluconoyl chloride afforded the corresponding mono- and /or diacylated products in varying yields (4-96%). Elaboration of the alkylated and acylated products has involved the reaction of hydroxy systems with diethyl chloro phosphate and chloro derivatives with triethyl phosphite in Arbuzov-type reactions to afford phosphorylated products. In all cases, products were fully characterized using 1- and 2-D NMR analysis and, where appropriate, high-resolution mass spectrometry. The application of Modgraph and ChemWindow NMR prediction programmes has been explored and the resulting data have been compared with experimental chemical shift assignments to confirm chemical structures and, in some cases, to establish the position of allylation or acylation. Experimental assignments were found to be generally comparable with the Modgraph data, but not always with the ChemWindow values. The docking of selected products in the 'active-site' of GS and their structural homology with ATP, both in their free and bound conformations have been studied using the ACCELERYS Cerius² platform. All the selected ATP mimics exhibit some form of interaction with the 'active-site' residues, and a number of them appear to be promising GS ligands.
- Full Text:
- Date Issued: 2008
Availability of pharmacoeconomic data and its use in the development of drug formularies in South Africa
- Authors: Keele, Mothobi Godfrey
- Date: 2008
- Subjects: Drugs -- Cost effectiveness , Pharmacy -- Economic aspects
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:10146 , http://hdl.handle.net/10948/685 , Drugs -- Cost effectiveness , Pharmacy -- Economic aspects
- Description: In an attempt to manage scarce health care resources and keep drug expenditure low, health care administrators worldwide have to make careful considerations regarding the choice of drugs to be provided to patients within their systems. One of the key strategies that is being employed to achieve this goal is the use of formularies. A major challenge in the formulary development process is to use pharmacoeconomics and outcomes research effectively to arrive at formularies that simultaneously provide patients with effective pharmacotherapy whilst maintaining financial stability. The extent to which this can be successfully achieved depends to a large extent on the availability of appropriate pharmacoeconomic data. The primary objectives of this study were to describe the availability and quality of literature pertaining to South African based pharmacoeconomic research, and to establish the manner in and extent to which pharmacoeconomic data is used in drug formulary decision-making processes, in both the private and public health care sectors in South Africa. A structured bibliographic search for South African pharmacoeconomic studies was conducted and a qualitative assessment of the identified studies which met the predetermined inclusion criteria was completed, using a pre-validated quality evaluation tool. In order to determine the use of pharmacoeconomic data in the formulary decisionmaking processes, by various stake holders in both the public and private of health care sectors in South Africa, a cross-sectional, descriptive study using a self-administered questionnaire was conducted. The results suggest that there is a limited availability of pharmacoeconomic research data in South Africa. Only 16 full pharmacoeconomic studies could be identified as having been published between 01 January 1995 and 30 June 2007. The quality of 3 of these studies was considered to be ‘dubious’, one study was found to be of high standard whilst the other 12 (74.95%) were of acceptable quality and thus could be considered as suitable to be used in formulary decision-making. The results of the national survey indicated that pharmacoeconomics is considered to be of importance and is used in formulary decision-making processes in both the public and private sectors. The primary source of pharmacoeconomic data used in formulary decisions appears to be international peer-reviewed publications. Of concern however, is the finding that this data, mostly from studies conducted outside of South Africa, is applied directly without sensitivity analysis or modelling. The results of the literature search and the subsequent quality appraisal suggest that pharmacoeconomic research and the use of pharmacoeconomic data in formulary decisions is at its infancy in South Africa. Thus efforts are needed to develop and grow the discipline of pharmacoeconomics in South Africa.
- Full Text:
- Date Issued: 2008
- Authors: Keele, Mothobi Godfrey
- Date: 2008
- Subjects: Drugs -- Cost effectiveness , Pharmacy -- Economic aspects
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: vital:10146 , http://hdl.handle.net/10948/685 , Drugs -- Cost effectiveness , Pharmacy -- Economic aspects
- Description: In an attempt to manage scarce health care resources and keep drug expenditure low, health care administrators worldwide have to make careful considerations regarding the choice of drugs to be provided to patients within their systems. One of the key strategies that is being employed to achieve this goal is the use of formularies. A major challenge in the formulary development process is to use pharmacoeconomics and outcomes research effectively to arrive at formularies that simultaneously provide patients with effective pharmacotherapy whilst maintaining financial stability. The extent to which this can be successfully achieved depends to a large extent on the availability of appropriate pharmacoeconomic data. The primary objectives of this study were to describe the availability and quality of literature pertaining to South African based pharmacoeconomic research, and to establish the manner in and extent to which pharmacoeconomic data is used in drug formulary decision-making processes, in both the private and public health care sectors in South Africa. A structured bibliographic search for South African pharmacoeconomic studies was conducted and a qualitative assessment of the identified studies which met the predetermined inclusion criteria was completed, using a pre-validated quality evaluation tool. In order to determine the use of pharmacoeconomic data in the formulary decisionmaking processes, by various stake holders in both the public and private of health care sectors in South Africa, a cross-sectional, descriptive study using a self-administered questionnaire was conducted. The results suggest that there is a limited availability of pharmacoeconomic research data in South Africa. Only 16 full pharmacoeconomic studies could be identified as having been published between 01 January 1995 and 30 June 2007. The quality of 3 of these studies was considered to be ‘dubious’, one study was found to be of high standard whilst the other 12 (74.95%) were of acceptable quality and thus could be considered as suitable to be used in formulary decision-making. The results of the national survey indicated that pharmacoeconomics is considered to be of importance and is used in formulary decision-making processes in both the public and private sectors. The primary source of pharmacoeconomic data used in formulary decisions appears to be international peer-reviewed publications. Of concern however, is the finding that this data, mostly from studies conducted outside of South Africa, is applied directly without sensitivity analysis or modelling. The results of the literature search and the subsequent quality appraisal suggest that pharmacoeconomic research and the use of pharmacoeconomic data in formulary decisions is at its infancy in South Africa. Thus efforts are needed to develop and grow the discipline of pharmacoeconomics in South Africa.
- Full Text:
- Date Issued: 2008
Baited traps may be an alternative to conventional pesticides in the integrated crop management of chicory (Compositae) in South Africa
- Midgley, John M, Hill, Martin P, Villet, Martin H
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6858 , http://hdl.handle.net/10962/d1011141 , http://dx.doi.org/10.1603/0022-0493(2008)101[99:BTMBAA]2.0.CO;2 , https://orcid.org/0000-0003-0579-5298
- Description: Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.
- Full Text:
- Date Issued: 2008
- Authors: Midgley, John M , Hill, Martin P , Villet, Martin H
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6858 , http://hdl.handle.net/10962/d1011141 , http://dx.doi.org/10.1603/0022-0493(2008)101[99:BTMBAA]2.0.CO;2 , https://orcid.org/0000-0003-0579-5298
- Description: Chicory, Chicorium intybus L. (Compositae), is a major field crop in the Eastern Cape Province of South Africa. Several pests feed on the leaves of the plant, resulting in reduced yield. The most important of these are the noctuid moths Helicoverpa armigera (Hübner), Chrysodeixis acuta (Walker), and Trichoplusia orichalcea (F.). The use of attract-and-kill traps offers an alternative to broad-based insecticides in the control of these species. Three fields were treated with normal insecticides and three fields with yellow-baited traps. Eight additional traps were placed in each field, with half of the traps containing the insecticide 2,2-dichlorovinyl dimethyl phosphate (dichlorvos) and half without dichlorvos; and half yellow and half green. Total moth numbers and nonphytophage diversity were measured from these eight traps. Although no differences in H. armigera or T. orichalcea catches were observed between insecticide- and trap-treated fields, numbers of C. acuta and the total number of moths were significantly higher in insecticide-treated fields. Yellow traps containing dichlorvos contained more moths than yellow traps without dichlorvos, or green traps with dichlorvos, or green traps without dichlorvos; but they also contained more nonphytophagous insects. Yellow traps also enhanced the catches of thrips on card traps associated with them. These results offer an opportunity for the South African chicory industry to reduce pesticide applications and thus mitigate environmental impacts.
- Full Text:
- Date Issued: 2008
Barriers and drivers to the implementation of the "clean development mechanism" within the Nelson Mandela Bay Municipality: a case study
- Authors: Wilson, Craig Michael
- Date: 2008
- Subjects: Nelson Mandela Metropolitan Municipality (Eastern Cape, South Africa) Local government -- South Africa -- Eastern Cape -- Case studies Climatic changes -- South Africa -- Eastern Cape -- Case studies Greenhouse gases -- Environmental aspects -- South Africa -- Eastern Cape -- Case studies Environmental economics -- South Africa -- Eastern Cape -- Case studies Greenhouse effect, Atmospheric Global warming
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:731 , http://hdl.handle.net/10962/d1003851
- Description: The global threat of climate change is one of the most crucial environmental issues facing the world in modern times. In response to this threat, international governments have drafted the Kyoto Protocol which included the Clean Development Mechanism (CDM). The CDM is a scheme which invited developing countries, like South Africa, to become involved in climate change mitigation projects. While South Africa has been identified as an attractive host country for CDM projects, research has revealed that it lags behind other developing countries in this regard. This study provides a theoretical background to the CDM and grounds the subject within the field of Environmental Economics. Following a literature review of factors that could influence the involvement of a municipality in CDM projects, this thesis undertook a case study of the barriers and drivers to CDM implementation within the Nelson Mandela Bay Municipality (NMBM). Use was made of semi-structured interviews, where a questionnaire was used to guide the researcher’s interview process. Five NMBM officers, who were likely to have been involved with CDM project implementation, were interviewed. Data collected was analyzed using a coding technique and was compared and contrasted to the literature in a process of explanation building. It was possible to elicit 14 factors that acted as CDM-barriers; seven that acted as CDM-drivers; and 10 that were required to change within the NMBM to encourage greater CDM involvement. Of the barriers, lack of awareness, poor political will and lack of funding emerged as the most inhibiting. Of the CDM-drivers, the potential financial benefits; ownership of infrastructure capable of producing carbon assets; and technology transfer emerged as the factors most likely to promote CDM involvement. With regards the factors that require change, it emerged that a positive response would result from a proactive stance by National Government on the CDM; the use of Public-Private-Partnerships to facilitate CDM projects; and improved communication and capacity building within the NMBM and the Nelson Mandela Bay business community. The main recommendation offered to the NMBM was for it to draft a Sustainable Development Policy as well as a formal sustainable development strategy to drive a coherent and consolidated approach to the Municipality’s involvement with CDM projects. Further, it was proposed that the NMBM should, lobby National Government for it to promulgate enabling legislation and a framework which would encourage CDM investment in South Africa; and engage with local business to promote the active involvement of the Nelson Mandela Bay with the implementation of CDM projects. Keywords: Global Warming, Kyoto Protocol, Clean Development Mechanism, Sustainable Development, Environmental Economics, Public Sector, Nelson Mandela Bay Municipality.
- Full Text:
- Date Issued: 2008
- Authors: Wilson, Craig Michael
- Date: 2008
- Subjects: Nelson Mandela Metropolitan Municipality (Eastern Cape, South Africa) Local government -- South Africa -- Eastern Cape -- Case studies Climatic changes -- South Africa -- Eastern Cape -- Case studies Greenhouse gases -- Environmental aspects -- South Africa -- Eastern Cape -- Case studies Environmental economics -- South Africa -- Eastern Cape -- Case studies Greenhouse effect, Atmospheric Global warming
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:731 , http://hdl.handle.net/10962/d1003851
- Description: The global threat of climate change is one of the most crucial environmental issues facing the world in modern times. In response to this threat, international governments have drafted the Kyoto Protocol which included the Clean Development Mechanism (CDM). The CDM is a scheme which invited developing countries, like South Africa, to become involved in climate change mitigation projects. While South Africa has been identified as an attractive host country for CDM projects, research has revealed that it lags behind other developing countries in this regard. This study provides a theoretical background to the CDM and grounds the subject within the field of Environmental Economics. Following a literature review of factors that could influence the involvement of a municipality in CDM projects, this thesis undertook a case study of the barriers and drivers to CDM implementation within the Nelson Mandela Bay Municipality (NMBM). Use was made of semi-structured interviews, where a questionnaire was used to guide the researcher’s interview process. Five NMBM officers, who were likely to have been involved with CDM project implementation, were interviewed. Data collected was analyzed using a coding technique and was compared and contrasted to the literature in a process of explanation building. It was possible to elicit 14 factors that acted as CDM-barriers; seven that acted as CDM-drivers; and 10 that were required to change within the NMBM to encourage greater CDM involvement. Of the barriers, lack of awareness, poor political will and lack of funding emerged as the most inhibiting. Of the CDM-drivers, the potential financial benefits; ownership of infrastructure capable of producing carbon assets; and technology transfer emerged as the factors most likely to promote CDM involvement. With regards the factors that require change, it emerged that a positive response would result from a proactive stance by National Government on the CDM; the use of Public-Private-Partnerships to facilitate CDM projects; and improved communication and capacity building within the NMBM and the Nelson Mandela Bay business community. The main recommendation offered to the NMBM was for it to draft a Sustainable Development Policy as well as a formal sustainable development strategy to drive a coherent and consolidated approach to the Municipality’s involvement with CDM projects. Further, it was proposed that the NMBM should, lobby National Government for it to promulgate enabling legislation and a framework which would encourage CDM investment in South Africa; and engage with local business to promote the active involvement of the Nelson Mandela Bay with the implementation of CDM projects. Keywords: Global Warming, Kyoto Protocol, Clean Development Mechanism, Sustainable Development, Environmental Economics, Public Sector, Nelson Mandela Bay Municipality.
- Full Text:
- Date Issued: 2008
Beneficial effects of medicinal plants in fish diseases
- Stratev, Deyan, Zhelyazkov, Georgi, Noundou, Xavier Siwe, Krause, Rui W M
- Authors: Stratev, Deyan , Zhelyazkov, Georgi , Noundou, Xavier Siwe , Krause, Rui W M
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123487 , vital:35447 , https://doi.org/10.1007/s10499-017-0219-x
- Description: Fish are constantly in contact with pathogens inhabiting water. High population density as well as poor hydrodynamic conditions and feeding lead to an increased sensitivity towards infections. In order to prevent major economic losses due to diseases, various medications are used for treatment and prevention of infections. The use of antimicrobial drugs in aquacultures could lead to emergence of resistance in pathogenic microorganisms. Alternatives are being sought over the last few years to replace antibiotics, and medicinal plants are one of available options for this purpose. These plants are rich in secondary metabolites and phytochemical compounds, which have an effect against viral, bacterial, and parasitic diseases in fish. Their main advantage is their natural origin and most of these plants do not represent threat for human health, the fish, and the environment. The goal of this review is to present information on the treatment of viral, bacterial, and parasitic diseases in fish through medicinal plants, with focus on the mechanisms of action of the identified secondary metabolites, fractions, or plant extracts.
- Full Text:
- Date Issued: 2008
- Authors: Stratev, Deyan , Zhelyazkov, Georgi , Noundou, Xavier Siwe , Krause, Rui W M
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/123487 , vital:35447 , https://doi.org/10.1007/s10499-017-0219-x
- Description: Fish are constantly in contact with pathogens inhabiting water. High population density as well as poor hydrodynamic conditions and feeding lead to an increased sensitivity towards infections. In order to prevent major economic losses due to diseases, various medications are used for treatment and prevention of infections. The use of antimicrobial drugs in aquacultures could lead to emergence of resistance in pathogenic microorganisms. Alternatives are being sought over the last few years to replace antibiotics, and medicinal plants are one of available options for this purpose. These plants are rich in secondary metabolites and phytochemical compounds, which have an effect against viral, bacterial, and parasitic diseases in fish. Their main advantage is their natural origin and most of these plants do not represent threat for human health, the fish, and the environment. The goal of this review is to present information on the treatment of viral, bacterial, and parasitic diseases in fish through medicinal plants, with focus on the mechanisms of action of the identified secondary metabolites, fractions, or plant extracts.
- Full Text:
- Date Issued: 2008
Between hotel mama and petrol station manager: the represatations of women's realities in a selection of African films
- Authors: O'Reilly, Kevin Joseph
- Date: 2008
- Subjects: Motion pictures -- Africa , Women in motion pictures
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8404 , http://hdl.handle.net/10948/789 , Motion pictures -- Africa , Women in motion pictures
- Description: The roles that women perform as depicted in African films are often dictated to by the type of society they find themselves in. At first glance traditional societies can be seen as oppressive because of the presence of certain cultural practices. Alternatively modern urban settings appear to offer women authority and empowerment through employment. However, with a closer examination one sees that the situation is not so simplistic. Such is the case when certain traditional practices that are deemed oppressive through a Western perspective, are still found in urban societies. Films on the subject of African women have to be cautious not place their characters in stereotypical roles. Therefore, it is not enough to merely portray African women as ‘oppressed’. African films that engage in a feminist critique need to present ‘realistic’ portrayals of African women. Such characters are layered and complex. The film Faat Kine (2000) depicts such a character in the authoritative protagonist Kine. The film La Vie est Belle (1987) examines the issue of polygamous marriages and patriarchy from the point of view of two African women living in France. Touki Bouki (1973) examines two young characters living in Senegal and questions the possibility of escape from ones circumstances. Traditional practices such as polygamous marriages are explored in Xala (1975), and Finzan (1989) explores cultural practices such as forced marriages and female circumcision. This treatise will consider women and work in both traditional society and urban settings. African feminism will also be investigated for the purpose of exploring common social perceptions of women in Africa.
- Full Text:
- Date Issued: 2008
- Authors: O'Reilly, Kevin Joseph
- Date: 2008
- Subjects: Motion pictures -- Africa , Women in motion pictures
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:8404 , http://hdl.handle.net/10948/789 , Motion pictures -- Africa , Women in motion pictures
- Description: The roles that women perform as depicted in African films are often dictated to by the type of society they find themselves in. At first glance traditional societies can be seen as oppressive because of the presence of certain cultural practices. Alternatively modern urban settings appear to offer women authority and empowerment through employment. However, with a closer examination one sees that the situation is not so simplistic. Such is the case when certain traditional practices that are deemed oppressive through a Western perspective, are still found in urban societies. Films on the subject of African women have to be cautious not place their characters in stereotypical roles. Therefore, it is not enough to merely portray African women as ‘oppressed’. African films that engage in a feminist critique need to present ‘realistic’ portrayals of African women. Such characters are layered and complex. The film Faat Kine (2000) depicts such a character in the authoritative protagonist Kine. The film La Vie est Belle (1987) examines the issue of polygamous marriages and patriarchy from the point of view of two African women living in France. Touki Bouki (1973) examines two young characters living in Senegal and questions the possibility of escape from ones circumstances. Traditional practices such as polygamous marriages are explored in Xala (1975), and Finzan (1989) explores cultural practices such as forced marriages and female circumcision. This treatise will consider women and work in both traditional society and urban settings. African feminism will also be investigated for the purpose of exploring common social perceptions of women in Africa.
- Full Text:
- Date Issued: 2008
Biodiversity of Salmonella strains isolated from selected water sources and wastewater discharge points in the Easern Cape Province of South Africa
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
- Authors: Mafu, Nwabisa Charity
- Date: 2008
- Subjects: Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Language: English
- Type: Thesis , Masters , MSc (Microbiology)
- Identifier: vital:11248 , http://hdl.handle.net/10353/74 , Biodiversity conservation -- South Africa -- Eastern Cape , Biodiversity -- South Africa -- Eastern Cape , Salmonella typhimurium
- Description: In this study, the diversity of forty Salmonella isolates from selected drinking water and wastewater sources in the Eastern Cape Province of South Africa was assessed using parameters such as protein and lipopolysaccharide profile analysis, DNA fingerprinting and antibiotic susceptibility profile as test indices. Wastewater samples from Amalinda, Shornville and Fort Hare wastewater plants, and water samples from Gogogo and Tyume rivers were collected on ice and transported to the laboratory of the department of Microbiology and Biochemistry, University of Fort Hare for processing. The DNA dendograms of Salmonella and the applied UPGMA revealed 4 similarity groups of the strains. Most of the strains recovered from Amalinda, Shornville, Fort Hare wastewater plants, Gogogo and Tyume rivers show a high percentage of genetic similarity. On the other hand, protein dendograms of Salmonella isolates revealed 2 similarity groups which varied widely. Also, the lipopolysaccharide dendograms revealed three similarity groups with the first similarity groups showing a very high relatedness between strains from different water sources. The second similarity group included 16 strains which formed a rather homogenous group, and the third similarity group formed a distinct group. Of the seven antibiotics and sulfonamides tested against the Salmonella species, five namely, neomycin, chloramphenicol, kanamycin, streptomycin and cotrimoxazole were significantly inhibitory, while the bacteria showed considerable resistance to doxycycline and sulphamethoxazole. Our results based on restriction digestion, SDS/PAGE and dendogram construction show that there is a high similarity between the forty Salmonella strains studied, and that these methods are valuable tools for evaluating the relatedness ofSalmonella species. Our observations have proffered a veritable reference point on the diversity of Salmonella strains in the studied area.
- Full Text:
- Date Issued: 2008
Biological responses to a resumption in river flow in a freshwater-deprived, permanently open Southern African estuary
- Vorwerk, Paul D, Froneman, P William, Paterson, Angus W, Strydom, Nadine A, Whitfield, A K
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, A K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
- Authors: Vorwerk, Paul D , Froneman, P William , Paterson, Angus W , Strydom, Nadine A , Whitfield, A K
- Date: 2008
- Language: English
- Type: text , Article
- Identifier: vital:6886 , http://hdl.handle.net/10962/d1011645
- Description: The Kariega Estuary is a freshwater-deprived system due to numerous impoundments in the catchment. This system has had little or no horizontal salinity gradient over the last 15 years, with hypersaline conditions sometimes predominating in the upper reaches. Following high rainfall events in the catchment during the spring of 2006, including a flood event (approximate 1:10 year) in August 2006, a series of riverine pulses entered the estuary and a horizontal salinity gradient was established. This study examined the influence of this freshwater pulse on four components of the biota within the estuary, namely the zooplankton, and larval, littoral and demersal fishes. The study demonstrated that in three of these components elevated densities were recorded following the riverine input, with only the littoral fishes retaining an almost constant density. In addition, changes in the relative contributions of the estuarine utilisation classes for all three fish groups examined indicated that freshwater input into these systems positively influences the abundances. This has significant implications for water managers as it demonstrates the importance of an Ecological Reserve (defined as ‘the water required to protect the aquatic ecosystems of the water resource’) for this system.
- Full Text:
- Date Issued: 2008
Bioprocess development for removal of nitrogenous compounds from precious metal refinery wastewater
- Manipura, Walappuly Mudiyanselage Janakasiri Aruna Shantha Bandara
- Authors: Manipura, Walappuly Mudiyanselage Janakasiri Aruna Shantha Bandara
- Date: 2008
- Subjects: Factory and trade waste Centralized industrial waste treatment facilities Metals -- Absorption and adsorption Metals -- Environmental aspects Water -- Purification -- Mathematical models Water quality management Water reuse Metals -- Refining Microbiology -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4076 , http://hdl.handle.net/10962/d1007341
- Description: Removal of nitrogenous compounds from precious metal refinery (PMR) wastewater is important in terms of avoiding eutrophication (environmental protection), metal recovery (increased overall process efficiency and value recovery) and reuse of treated water (maximum use of natural resources). Extreme pH conditions (4 to 13 depending on the wastewater stream), high chemical oxygen demand (> 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.
- Full Text:
- Date Issued: 2008
- Authors: Manipura, Walappuly Mudiyanselage Janakasiri Aruna Shantha Bandara
- Date: 2008
- Subjects: Factory and trade waste Centralized industrial waste treatment facilities Metals -- Absorption and adsorption Metals -- Environmental aspects Water -- Purification -- Mathematical models Water quality management Water reuse Metals -- Refining Microbiology -- Research
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4076 , http://hdl.handle.net/10962/d1007341
- Description: Removal of nitrogenous compounds from precious metal refinery (PMR) wastewater is important in terms of avoiding eutrophication (environmental protection), metal recovery (increased overall process efficiency and value recovery) and reuse of treated water (maximum use of natural resources). Extreme pH conditions (4 to 13 depending on the wastewater stream), high chemical oxygen demand (> 10,000 mg/I), numerous metals and high concentrations of those metals (> 20 mg/l of platinum group metals) in the wastewater are the main challenges for biological removal of nitrogenous compounds from PMR wastewater. Nitrogenous compounds such as NH₄⁺-N and N0₃-N are strong metal ligands, which make it difficult to recover metals from the wastewater. Therefore, a bioprocess was developed for removal of nitrogenous compounds from carefully simulated PMR wastewater. A preliminary investigation of metal wastewater was carried out to determine its composition and physico-chemical properties, the ability to nitrify and denitrify under different pH conditions and denitrification with different carbon Source compounds and amounts. Even at pH 4, nitrification could be carried out. A suitable hydraulic retention time was found to be 72 hours. There was no significant difference between sodium acetate and sodium lactate as carbon sources for denitrification. Based on these results, a reactor comparison study was carried out using simulated PMR wastewater in three types of reactors: continuously stirred tank reactor (CSTR), packed-bed reactor (PBR) and airlift suspension reactor (ALSR). These reactors were fed with 30 mg/l of Rh bound in an NH₄⁺ based compound (Claus salt: pentaaminechlororhodium (III) dichloride). Total nitrogen removal efficiencies of > 68 % , > 79 % and > 45 % were obtained in the CSTR, PBR and ALSR, respectively. Serially connected CSTR-PBR and PBR-CSTR reactor configurations were then studied to determine the best configuration for maximum removal of nitrogenous compounds from the wastewater. The PBR-CSTR configuration gave consistent biomass retention and automatic pH control in the CSTR. Ammonium removal efficiencies > 95 % were achieved in both reactors. As poor nitrate removal was observed a toxicity study was carried out using respirometry and the half saturation inhibition coefficients for Pt, Pd, Rh and Ru were found to be 15.81, 25.00, 33.34 and 39.25 mg/l, respectively. A mathematical model was developed to describe the nitrogen removal in PMR wastewater using activated sludge model number 1 (ASMl), two step nitrification and metal toxicity. An operational protocol was developed based on the literature review, experimental work and simulation results. The optimum reactor configuration under the set conditions (20 mg/I of Rh and < 100 mg/I of NH₄⁺-N) was found to be PBR-CSTR-PBR process, which achieved overall NH₄⁺-N and N0₃⁻-N removal efficiencies of > 90 % and 95 %, respectively. Finally, a rudimentary microbial characterisation was carried out on subsamples from the CSTR and PBRsecondary. It was found that the CSTR biomass consisted of both rods and cocci while PBRsecondary consisted of rods only. Based on these experimental works, further research needs and recommendations were made for optimisation of the developed bioprocess for removal of nitrogenous compounds from PMR wastewater.
- Full Text:
- Date Issued: 2008
Biosorption of precious metals from synthetic and refinery wastewaters by immobilized saccharomyces cerevisiae
- Authors: Mack, Cherie-Lynn
- Date: 2008
- Subjects: Metals -- Refining Metals -- Absorption and adsorption Saccharomyces cerevisiae Factory and trade waste Water reuse Platinum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4071 , http://hdl.handle.net/10962/d1006977
- Description: The process of precious metal refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not an effective means for selective recovery of precious metals from a wastewater. Biosorption, the ability of certain types of biomass to bind and concentrate metals from even very dilute aqueous solutions, may be an effective point-source metal recovery strategy. The yeast, Saccharomyces cerevisiae, has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. As such, it represents a possible precious metal sorbent for application to refining wastewaters. In this investigation, S. cerevisiae biomass was immobilized, using polyethyleneimine and glutaraldehyde, to produce a suitable sorbent, which was found to be capable of high platinum uptake (150 to 170 mg/g) at low pH (< 2). The sorption mechanism was elucidated and found to be a chemical reaction, which made effective desorption impossible. The sorption process was investigated in a packed bed column conformation, the results of which showed that the diameter and height of the column require further optimization in order to attain the metal uptake values achieved in the batch studies. When applied to a refinery wastewater, two key wastewater characteristics limited the success of the sorption process; the high inorganic ion content and the complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilized yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before the biosorption process can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to an industrial wastewater.
- Full Text:
- Date Issued: 2008
- Authors: Mack, Cherie-Lynn
- Date: 2008
- Subjects: Metals -- Refining Metals -- Absorption and adsorption Saccharomyces cerevisiae Factory and trade waste Water reuse Platinum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4071 , http://hdl.handle.net/10962/d1006977
- Description: The process of precious metal refining can be up to 99.99% efficient at best, and although it may seem small, the amount of valuable metal lost to waste streams is appreciable enough to warrant recovery. The method currently used to remove entrained metal ions from refinery wastewaters, chemical precipitation, is not an effective means for selective recovery of precious metals from a wastewater. Biosorption, the ability of certain types of biomass to bind and concentrate metals from even very dilute aqueous solutions, may be an effective point-source metal recovery strategy. The yeast, Saccharomyces cerevisiae, has been found capable of sorbing numerous precious and base metals, and is a cheap and abundant source of biomass. As such, it represents a possible precious metal sorbent for application to refining wastewaters. In this investigation, S. cerevisiae biomass was immobilized, using polyethyleneimine and glutaraldehyde, to produce a suitable sorbent, which was found to be capable of high platinum uptake (150 to 170 mg/g) at low pH (< 2). The sorption mechanism was elucidated and found to be a chemical reaction, which made effective desorption impossible. The sorption process was investigated in a packed bed column conformation, the results of which showed that the diameter and height of the column require further optimization in order to attain the metal uptake values achieved in the batch studies. When applied to a refinery wastewater, two key wastewater characteristics limited the success of the sorption process; the high inorganic ion content and the complex speciation of the platinum ions. The results proved the concept principle of platinum recovery by immobilized yeast biosorption and indicated that a more detailed understanding of the platinum speciation within the wastewater is required before the biosorption process can be applied. Overall, the sorption of platinum by the S. cerevisiae sorbent was demonstrated to be highly effective in principle, but the complexity of the wastewater requires that pretreatment steps be taken before the successful application of this process to an industrial wastewater.
- Full Text:
- Date Issued: 2008
Black parental involvement in education
- Authors: Mbokodi, Sindiswa Madgie
- Date: 2008
- Subjects: Education -- Parent participation -- South Africa , Parent-teacher relationships -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9518 , http://hdl.handle.net/10948/1013 , Education -- Parent participation -- South Africa , Parent-teacher relationships -- South Africa
- Description: The study was conducted in the backdrop of Section 24(1)(a) of the South African Schools Act (SASA) 84 of 1996 which promulgated that parents should be involved in the education of their children. To fulfil this requirement, each school is expected to have a legally constituted School Governing Body (SGB) as part of school governance. The involvement of the SGB does not exclude parents involving themselves in school activities as individuals but as organised groups geared towards working on a specific project of the school. Involvement also implies helping the child at home. The study investigated the extent to which black parents involve themselves in school activities as envisaged by the SASA. Conceptual literature relating to issues of parental involvement in school was reviewed. Specifically the concept parent/parental involvement as it relates to black parents was explored. Factors promoting or hindering parental involvement in school were also examined. The research is qualitative. Participants included principals, teachers, learners and chairpersons of school governing bodies of ten selected schools in the major townships of Port Elizabeth. Views and experiences of participants were captured and explained through in-depth interviews and observations. Results are discussed in relation to the relevant literature, allowing grounded theory to emerge. What emerged was a desperate situation of non-involvement of black parents in school activities largely because of the failure of the Department of Education (DoE) to capacitate all parties involved in strategies to involve parents in school. The potential for generalizability and transferability is discussed in the report and possible intervention strategies are recommended at micro- and macro-levels. The study demonstrates that the DoE needs to follow up on its policies to ensure that the envisaged change is realized.
- Full Text:
- Date Issued: 2008
- Authors: Mbokodi, Sindiswa Madgie
- Date: 2008
- Subjects: Education -- Parent participation -- South Africa , Parent-teacher relationships -- South Africa
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9518 , http://hdl.handle.net/10948/1013 , Education -- Parent participation -- South Africa , Parent-teacher relationships -- South Africa
- Description: The study was conducted in the backdrop of Section 24(1)(a) of the South African Schools Act (SASA) 84 of 1996 which promulgated that parents should be involved in the education of their children. To fulfil this requirement, each school is expected to have a legally constituted School Governing Body (SGB) as part of school governance. The involvement of the SGB does not exclude parents involving themselves in school activities as individuals but as organised groups geared towards working on a specific project of the school. Involvement also implies helping the child at home. The study investigated the extent to which black parents involve themselves in school activities as envisaged by the SASA. Conceptual literature relating to issues of parental involvement in school was reviewed. Specifically the concept parent/parental involvement as it relates to black parents was explored. Factors promoting or hindering parental involvement in school were also examined. The research is qualitative. Participants included principals, teachers, learners and chairpersons of school governing bodies of ten selected schools in the major townships of Port Elizabeth. Views and experiences of participants were captured and explained through in-depth interviews and observations. Results are discussed in relation to the relevant literature, allowing grounded theory to emerge. What emerged was a desperate situation of non-involvement of black parents in school activities largely because of the failure of the Department of Education (DoE) to capacitate all parties involved in strategies to involve parents in school. The potential for generalizability and transferability is discussed in the report and possible intervention strategies are recommended at micro- and macro-levels. The study demonstrates that the DoE needs to follow up on its policies to ensure that the envisaged change is realized.
- Full Text:
- Date Issued: 2008
Breaking into the conversation: cultural value and the role of the South African National Arts Festival from apartheid to democracy
- Snowball, Jeanette D, Webb, Arthur C M
- Authors: Snowball, Jeanette D , Webb, Arthur C M
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71311 , vital:29832 , https://doi.org/10.1080/10286630802106326
- Description: The paper examines the value of the South African National Arts Festival (NAF) in the transition to democracy using theories of cultural capital. NAF history from 1974 to 2004 is used to argue that the Festival provided an important arena for the expression of political resistance in the 1980s and, to some degree, continues to do so today. It is concluded that an important part of the value of the arts is their ability to provide a forum for debating the goals and values of society and that individualistic utility theory is not always successful in measuring such social value.
- Full Text:
- Date Issued: 2008
- Authors: Snowball, Jeanette D , Webb, Arthur C M
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/71311 , vital:29832 , https://doi.org/10.1080/10286630802106326
- Description: The paper examines the value of the South African National Arts Festival (NAF) in the transition to democracy using theories of cultural capital. NAF history from 1974 to 2004 is used to argue that the Festival provided an important arena for the expression of political resistance in the 1980s and, to some degree, continues to do so today. It is concluded that an important part of the value of the arts is their ability to provide a forum for debating the goals and values of society and that individualistic utility theory is not always successful in measuring such social value.
- Full Text:
- Date Issued: 2008
Building and Woodworkers International (BWI) Baseline gender survey
- Authors: Benjamin, Nina
- Date: 2008
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60109 , vital:27737
- Description: This Gender Survey is about exploring both the nature of as well as the shifts in the gender relations between men women in the construction sector. The report is defining gender relations as the power relations between men and women. In the context of the construction sector, workers and particularly semi and unskilled workers generally have appalling working conditions. These conditions affect both men and women workers but the vast majority of women workers find themselves right at the bottom of a hierarchy that is shaped by class, race and gender. Large multinational construction companies are still owned and controlled by rich white men while black women, youth and the disabled find themselves right at the bottom of the hierarchy.
- Full Text:
- Date Issued: 2008
- Authors: Benjamin, Nina
- Date: 2008
- Language: English
- Type: article , text
- Identifier: http://hdl.handle.net/10962/60109 , vital:27737
- Description: This Gender Survey is about exploring both the nature of as well as the shifts in the gender relations between men women in the construction sector. The report is defining gender relations as the power relations between men and women. In the context of the construction sector, workers and particularly semi and unskilled workers generally have appalling working conditions. These conditions affect both men and women workers but the vast majority of women workers find themselves right at the bottom of a hierarchy that is shaped by class, race and gender. Large multinational construction companies are still owned and controlled by rich white men while black women, youth and the disabled find themselves right at the bottom of the hierarchy.
- Full Text:
- Date Issued: 2008
Business process security maturity: a paradigm convergence
- Authors: Box, Debra
- Date: 2008
- Subjects: Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9785 , http://hdl.handle.net/10948/722 , Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Description: Information technology developments in software and hardware have enabled radical changes in information systems, culminating in the paradigm Business Process Management. There has been a concomitant rise in the importance of information security and security engineering due to the increased reliance by society on information. Information is seen as a critical success factor which needs protection. Information security is the response to increased hazards created through recent innovations in Web technology and the advent of intra and inter enterprise-wide systems. Security engineering is based on a variety of codes of practice and security metrics which aim at ameliorating these increased security hazards. Its aim is to produce a balanced set of security needs which are integrated into the system activities to establish confidence in the effectiveness of the security counter-measures. It is generally accepted that security should be applied in an integrated approach, for example, in Information Systems development. This has proved to be a noble thought but is the exception to the rule. Security, historically, is generally applied as an after-thought in an Information Technology implementation. This motivated the concept of formulating a model of integrating security inherently within the paradigm of BPM. The overarching requirements of the model are to align the overall organisational security initiatives and ensure continuous improvement through constant evaluation and adaptation of the security processes. It is the intention of this research to show that these requirements are achievable through aligning the process management methodology of BPM, with the security paradigms of Information Security Management (using the ISO 17799 standard) and security engineering (using the Systems Security Engineering Capability Maturity Model – SSE-CMM). The aim of the Business Process Security Maturity model as the output of this research, is to link the SSE-CMM, as the security metric and appraisal method, to the ISO 17799 security standard, which provides the guidance for the information security management framework and security control selection, within the Business Process Management environment. The SSE-CMM, as the security version of the Capability Maturity Model, provides the necessary strategy to control the security engineering processes that support the information systems and it maintains that as processes mature they become more predictable, effective and manageable. The aim of the model is to provide an integrated, mature security strategy within the business process and monitor and correct the security posture of the implemented counter-measures.
- Full Text:
- Date Issued: 2008
- Authors: Box, Debra
- Date: 2008
- Subjects: Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: vital:9785 , http://hdl.handle.net/10948/722 , Management information systems , Reengineering (Management) , Organizational change , Systems engineering , Information resources management
- Description: Information technology developments in software and hardware have enabled radical changes in information systems, culminating in the paradigm Business Process Management. There has been a concomitant rise in the importance of information security and security engineering due to the increased reliance by society on information. Information is seen as a critical success factor which needs protection. Information security is the response to increased hazards created through recent innovations in Web technology and the advent of intra and inter enterprise-wide systems. Security engineering is based on a variety of codes of practice and security metrics which aim at ameliorating these increased security hazards. Its aim is to produce a balanced set of security needs which are integrated into the system activities to establish confidence in the effectiveness of the security counter-measures. It is generally accepted that security should be applied in an integrated approach, for example, in Information Systems development. This has proved to be a noble thought but is the exception to the rule. Security, historically, is generally applied as an after-thought in an Information Technology implementation. This motivated the concept of formulating a model of integrating security inherently within the paradigm of BPM. The overarching requirements of the model are to align the overall organisational security initiatives and ensure continuous improvement through constant evaluation and adaptation of the security processes. It is the intention of this research to show that these requirements are achievable through aligning the process management methodology of BPM, with the security paradigms of Information Security Management (using the ISO 17799 standard) and security engineering (using the Systems Security Engineering Capability Maturity Model – SSE-CMM). The aim of the Business Process Security Maturity model as the output of this research, is to link the SSE-CMM, as the security metric and appraisal method, to the ISO 17799 security standard, which provides the guidance for the information security management framework and security control selection, within the Business Process Management environment. The SSE-CMM, as the security version of the Capability Maturity Model, provides the necessary strategy to control the security engineering processes that support the information systems and it maintains that as processes mature they become more predictable, effective and manageable. The aim of the model is to provide an integrated, mature security strategy within the business process and monitor and correct the security posture of the implemented counter-measures.
- Full Text:
- Date Issued: 2008
Camphor derivatives in asymmetric synthesis: a synthetic, mechanistic and theoretical study
- Authors: Lobb, Kevin Alan
- Date: 2008
- Subjects: Chemistry, Organic -- Research Esters Organic compounds -- Synthesis Alkylation Chemical reactions -- Computer simulation Chemical kinetics Camphor Cinnamomum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4414 , http://hdl.handle.net/10962/d1006770
- Description: A series of 3,3-ethylenedioxy-exo- and endo- bornyl esters have been prepared and subjected to α-benzylation using lithium diisopropylamide and benzyl bromide. In the exo-series of esters the diastereofacial selectivity of benzylation was found to improve (up to 34% d.e.) as the steric bulk of the O-alkyl group increased, whereas in the endo-series, a surprising decrease in stereoselectivity was observed as the steric bulk increased – an observation attributed to flexibility of the metal-coordinated endo-enolate system, compared to the relative rigidity of the exo analogues. The conformational options for each series was explored at the density functional theory level. Reductive cyclization of a range of specially prepared N-carbobenzyloxy-amino acid esters has been shown to afford the corresponding derivatives, contrary to previous reports that the cyclization is limited to the glycine derivative. The cyclization sequence has been explored in detail, and the yield has been shown to be critically dependent on the stereochemistry of the α-amino acid moiety. Moreover, it seems that reductive cyclization occurs more readily with the endo- rather than the exo-bornyl N-CBZ-amino acid esters. Molecular modelling of relevant transition states at the DFT levels indicates that L-amino acid-derived systems should cyclize preferably in the exo-series and D-amino acid-derived systems should cyclize preferably in the endo series. Studies of alkylation of an iminolactone system have reported an interesting anomaly - exo-methylation is observed while endo-alkylation predominates for larger alkyl groups. This has been studied in detail at the DFT level, and the anomaly is attributed to thermodynamic control in the methyl case, whereas kinetic control is the norm in this system. Preliminary computer modelling of the intramolecular rearrangement of a 3,3-xylylbornyl system at the HF/STO-3G level raised doubts concerning the structure assigned by Evans to one of the rearrangement products, prompting an X-ray crystallographic analysis and leading to the revision of its structure from a pinene to a camphene derivative. The previously elusive spiro[bornane-3,2’-indan]-2-exo-tosylate has been successfully isolated, and the kinetics of its ready decomposition to the two camphene products has been followed by 1H NMR spectroscopy. The endo-tosylate analogue, on the other hand, was found to be remarkably stable. Kinetic data obtained for rearrangement of this exo-bornyl tosylate have indicated the operation of tandem autocatalytic and pseudo-first-order transformations leading sequentially to the two isomeric camphene products. An extensive coset analysis of all possible rearrangement processes of the initially-formed cation formed from decomposition of the exo-tosylate has afforded a graph containing 336 classical cations (modelled at the AM1 and B3LYP levels) and 526 transition-state complexes (modelled at the AM1 level). This analysis afforded a viable 4-step classical mechanism connecting the first camphene product with the second. A more realistic study, involving non-classical carbocations, has afforded a graph of all possible (classical and non-classical) cations that could be formed by rearrangment of the initiallyformed cation. The resulting graph confirms that the only energetically feasible path corresponds to the classical mechanism, but simply involves two steps, including a novel, concerted Wagner-Meerwein – 6,2-hydride shift – Wagner-Meerwein rearrangement.
- Full Text:
- Date Issued: 2008
- Authors: Lobb, Kevin Alan
- Date: 2008
- Subjects: Chemistry, Organic -- Research Esters Organic compounds -- Synthesis Alkylation Chemical reactions -- Computer simulation Chemical kinetics Camphor Cinnamomum
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4414 , http://hdl.handle.net/10962/d1006770
- Description: A series of 3,3-ethylenedioxy-exo- and endo- bornyl esters have been prepared and subjected to α-benzylation using lithium diisopropylamide and benzyl bromide. In the exo-series of esters the diastereofacial selectivity of benzylation was found to improve (up to 34% d.e.) as the steric bulk of the O-alkyl group increased, whereas in the endo-series, a surprising decrease in stereoselectivity was observed as the steric bulk increased – an observation attributed to flexibility of the metal-coordinated endo-enolate system, compared to the relative rigidity of the exo analogues. The conformational options for each series was explored at the density functional theory level. Reductive cyclization of a range of specially prepared N-carbobenzyloxy-amino acid esters has been shown to afford the corresponding derivatives, contrary to previous reports that the cyclization is limited to the glycine derivative. The cyclization sequence has been explored in detail, and the yield has been shown to be critically dependent on the stereochemistry of the α-amino acid moiety. Moreover, it seems that reductive cyclization occurs more readily with the endo- rather than the exo-bornyl N-CBZ-amino acid esters. Molecular modelling of relevant transition states at the DFT levels indicates that L-amino acid-derived systems should cyclize preferably in the exo-series and D-amino acid-derived systems should cyclize preferably in the endo series. Studies of alkylation of an iminolactone system have reported an interesting anomaly - exo-methylation is observed while endo-alkylation predominates for larger alkyl groups. This has been studied in detail at the DFT level, and the anomaly is attributed to thermodynamic control in the methyl case, whereas kinetic control is the norm in this system. Preliminary computer modelling of the intramolecular rearrangement of a 3,3-xylylbornyl system at the HF/STO-3G level raised doubts concerning the structure assigned by Evans to one of the rearrangement products, prompting an X-ray crystallographic analysis and leading to the revision of its structure from a pinene to a camphene derivative. The previously elusive spiro[bornane-3,2’-indan]-2-exo-tosylate has been successfully isolated, and the kinetics of its ready decomposition to the two camphene products has been followed by 1H NMR spectroscopy. The endo-tosylate analogue, on the other hand, was found to be remarkably stable. Kinetic data obtained for rearrangement of this exo-bornyl tosylate have indicated the operation of tandem autocatalytic and pseudo-first-order transformations leading sequentially to the two isomeric camphene products. An extensive coset analysis of all possible rearrangement processes of the initially-formed cation formed from decomposition of the exo-tosylate has afforded a graph containing 336 classical cations (modelled at the AM1 and B3LYP levels) and 526 transition-state complexes (modelled at the AM1 level). This analysis afforded a viable 4-step classical mechanism connecting the first camphene product with the second. A more realistic study, involving non-classical carbocations, has afforded a graph of all possible (classical and non-classical) cations that could be formed by rearrangment of the initiallyformed cation. The resulting graph confirms that the only energetically feasible path corresponds to the classical mechanism, but simply involves two steps, including a novel, concerted Wagner-Meerwein – 6,2-hydride shift – Wagner-Meerwein rearrangement.
- Full Text:
- Date Issued: 2008
Challenges and opportunities: an evaluation of the implementation of gender mainstreaming in South African government departments, with specific reference to the department of justice and constitutional development (DoJ&CD) and the department of foreign affairs (DFA)
- Authors: Sedibelwana, Maria Valerie
- Date: 2008
- Subjects: Women government executives , Sex discrimination , Women in the civil service -- South Africa , Gender mainstreaming -- South Africa
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:8243 , http://hdl.handle.net/10948/757 , Women government executives , Sex discrimination , Women in the civil service -- South Africa , Gender mainstreaming -- South Africa
- Description: The aim of this research project is to conduct an evaluation on the implementation of gender mainstreaming in South African government departments, with specific reference to the Department of Justice and Constitutional Development (DoJ&CD) and the Department of Foreign Affairs (DFA). The research project is based on the hypothesis that despite the existence of a National Gender Machinery, Gender Focal Points (GFPs) face numerous challenges in implementing gender mainstreaming, due to various internal and external factors. Based on the two case studies, the research project concludes that despite a strong commitment from government, GFPs still face challenges in effectively implementing gender mainstreaming. This is due to a lack of accountability, an understanding of the concept of gender mainstreaming, as well as a lack of resources. Furthermore, systemic weaknesses within the National Gender Machinery are exacerbating the challenges faced GFP
- Full Text:
- Date Issued: 2008
- Authors: Sedibelwana, Maria Valerie
- Date: 2008
- Subjects: Women government executives , Sex discrimination , Women in the civil service -- South Africa , Gender mainstreaming -- South Africa
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:8243 , http://hdl.handle.net/10948/757 , Women government executives , Sex discrimination , Women in the civil service -- South Africa , Gender mainstreaming -- South Africa
- Description: The aim of this research project is to conduct an evaluation on the implementation of gender mainstreaming in South African government departments, with specific reference to the Department of Justice and Constitutional Development (DoJ&CD) and the Department of Foreign Affairs (DFA). The research project is based on the hypothesis that despite the existence of a National Gender Machinery, Gender Focal Points (GFPs) face numerous challenges in implementing gender mainstreaming, due to various internal and external factors. Based on the two case studies, the research project concludes that despite a strong commitment from government, GFPs still face challenges in effectively implementing gender mainstreaming. This is due to a lack of accountability, an understanding of the concept of gender mainstreaming, as well as a lack of resources. Furthermore, systemic weaknesses within the National Gender Machinery are exacerbating the challenges faced GFP
- Full Text:
- Date Issued: 2008
Challenges faced by secondary school teachers in integrating ICT into the curriculum: a multiple case study in the Grahamstown Circuit
- Maholwana-Sotashe, Nikiwe Laura
- Authors: Maholwana-Sotashe, Nikiwe Laura
- Date: 2008
- Subjects: Educational technology -- South Africa -- Grahamstown Education, Secondary -- South Africa -- Grahamstown -- Data processing Information technology -- Study and teaching (Secondary) -- South Africa -- Grahamstown Internet in education -- South Africa -- Grahamstown Information technology -- South Africa -- Grahamstown Computer-assisted instruction -- South Africa -- Grahamstown Education, Secondary -- Curricula -- South Africa -- Grahamstown Educational innovations
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1445 , http://hdl.handle.net/10962/d1003326
- Description: The integration of Information and Communication Technology (ICT) into the curriculum has become the major issue worldwide. The education system does not only pursue the integration of ICT into the curriculum because of its popularity in the market system, but because of the role it is perceived to play in the changing curriculum (encourages active construction of knowledge). According to White Paper 7 e-Education policy (2004:17) every South African learner should be able to use ICTs confidently and creatively to develop the skills and knowledge they need to achieve personal goals and to be full participants in the global community by 2013. The central role played by teachers in teaching and learning requires them to have a holistic understanding of ICT integration. Furthermore they should be able to analyse when ICT integration is appropriate according to what is expected from the learner in the teaching and learning process. Drawing on the evidence from a survey of nine secondary schools in the Grahamstown Circuit of the Eastern Cape, this study examines how teachers from three different types of secondary schools: Former Department of Education (FDET) schools, Former House of Representatives (FHOR) schools and Former Model C (FMC) schools perceive the integration of ICTs in the curriculum. The salient ideas of how teachers perceive the integration of ICTs into the curriculum emerge from what they view as benefits of using ICT and what they view as challenges of integrating ICT into the curriculum. Contrary to expectations, the degree of ICT integration within the curriculum did not correspond directly with the availability of sufficient hardware, software or Internet connectivity at the participating schools.
- Full Text:
- Date Issued: 2008
- Authors: Maholwana-Sotashe, Nikiwe Laura
- Date: 2008
- Subjects: Educational technology -- South Africa -- Grahamstown Education, Secondary -- South Africa -- Grahamstown -- Data processing Information technology -- Study and teaching (Secondary) -- South Africa -- Grahamstown Internet in education -- South Africa -- Grahamstown Information technology -- South Africa -- Grahamstown Computer-assisted instruction -- South Africa -- Grahamstown Education, Secondary -- Curricula -- South Africa -- Grahamstown Educational innovations
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1445 , http://hdl.handle.net/10962/d1003326
- Description: The integration of Information and Communication Technology (ICT) into the curriculum has become the major issue worldwide. The education system does not only pursue the integration of ICT into the curriculum because of its popularity in the market system, but because of the role it is perceived to play in the changing curriculum (encourages active construction of knowledge). According to White Paper 7 e-Education policy (2004:17) every South African learner should be able to use ICTs confidently and creatively to develop the skills and knowledge they need to achieve personal goals and to be full participants in the global community by 2013. The central role played by teachers in teaching and learning requires them to have a holistic understanding of ICT integration. Furthermore they should be able to analyse when ICT integration is appropriate according to what is expected from the learner in the teaching and learning process. Drawing on the evidence from a survey of nine secondary schools in the Grahamstown Circuit of the Eastern Cape, this study examines how teachers from three different types of secondary schools: Former Department of Education (FDET) schools, Former House of Representatives (FHOR) schools and Former Model C (FMC) schools perceive the integration of ICTs in the curriculum. The salient ideas of how teachers perceive the integration of ICTs into the curriculum emerge from what they view as benefits of using ICT and what they view as challenges of integrating ICT into the curriculum. Contrary to expectations, the degree of ICT integration within the curriculum did not correspond directly with the availability of sufficient hardware, software or Internet connectivity at the participating schools.
- Full Text:
- Date Issued: 2008
Changing words and worlds?: a phenomenological study of the acquisition of an academic literacy
- Authors: Thomson, Carol Irene
- Date: 2008
- Subjects: Education -- Study and teaching (Higher) -- South Africa Universities and colleges -- South Africa College student development programs -- South Africa Literacy -- South Africa Education, Higher -- Philosophy Educational change -- South Africa Phenomenology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1446 , http://hdl.handle.net/10962/d1003327
- Description: This study is contextualised within the field of post-graduate, continuing teacher education, and the vibrant and demanding policy context that has characterised higher education in post-apartheid South Africa. Situated within a module specifically designed to address what is commonly understood to be the academic literacy development needs of students in the Bachelor of Education Honours programme at the former University of Natal, it aims to unveil the lived experiences of students taking this module. The module, Reading and Writing Academic Texts (RWAT), was developed in direct response to academics’ call that something be done about the ‘problem’ of students’ reading and writing proficiency. As a core, compulsory module, RWAT was informed by Systemic Functional Linguistics and drew on Genre Theory for its conceptual and theoretical framework. It foregrounded the genre of the academic argument as the key academic literacy that was taught. The motivation for this study came from my own increasing concern that the theoretical and conceptual framework we had adopted for the module was emerging as an inherently limiting and formulaic model of literacy, and was resulting in students exiting the module with little or no ‘critical’ perspective on any aspect of literacy as social practice. I was also keen, in a climate of increasing de-personalisation and the massification of education, to reinstate the personal. Thus, I chose to focus on individual lives, and through an exploration of a small group of participants’ ‘lived’ experiences of the RWAT module, ascertain what it is like to acquire an academic literacy. The key research question is, therefore: What is it like to acquire an academic literacy? The secondary research question is: How is this experience influenced by the mode of delivery in which it occurs? For its conceptual and theoretical framing, this study draws on social literacy theory and phenomenology, the latter as both a philosophy and a methodology. However, although the study has drawn significantly on the phenomenological tradition for inspiration and direction, it has not done so uncritically. Thus, the study engages with phenomenology-as-philosophy in great depth before turning to phenomenology-as-methodology, in order to arrive at a point where the methods and procedures applied in it, are justified. The main findings of the study suggest that, despite the RWAT module espousing an ideological model (Street, 1984) of literacy in its learning materials and readings, participants came very much closer to experiencing an autonomous model of literacy (Street, 1984). The data shows that the RWAT module was largely inadequate to the task of inducting participants into the ‘situated practices’ and ‘situated meanings’ of the Discourse of Genre Theory and/or the academy, hence the many ‘lived’ difficulties participants experienced. The data also highlights the ease with which an autonomous model of literacy can come to govern practice and student experience even when curriculum intention is underpinned by an ideological position on literacy as social practice. Finally, the study suggests that the research community in South Africa, characterised as it is by such diversity, would be enriched by more studies derived from phenomenology, and a continuing engagement with phenomenology-as-a-movement in order to both challenge and expand its existing framework.
- Full Text:
- Date Issued: 2008
- Authors: Thomson, Carol Irene
- Date: 2008
- Subjects: Education -- Study and teaching (Higher) -- South Africa Universities and colleges -- South Africa College student development programs -- South Africa Literacy -- South Africa Education, Higher -- Philosophy Educational change -- South Africa Phenomenology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1446 , http://hdl.handle.net/10962/d1003327
- Description: This study is contextualised within the field of post-graduate, continuing teacher education, and the vibrant and demanding policy context that has characterised higher education in post-apartheid South Africa. Situated within a module specifically designed to address what is commonly understood to be the academic literacy development needs of students in the Bachelor of Education Honours programme at the former University of Natal, it aims to unveil the lived experiences of students taking this module. The module, Reading and Writing Academic Texts (RWAT), was developed in direct response to academics’ call that something be done about the ‘problem’ of students’ reading and writing proficiency. As a core, compulsory module, RWAT was informed by Systemic Functional Linguistics and drew on Genre Theory for its conceptual and theoretical framework. It foregrounded the genre of the academic argument as the key academic literacy that was taught. The motivation for this study came from my own increasing concern that the theoretical and conceptual framework we had adopted for the module was emerging as an inherently limiting and formulaic model of literacy, and was resulting in students exiting the module with little or no ‘critical’ perspective on any aspect of literacy as social practice. I was also keen, in a climate of increasing de-personalisation and the massification of education, to reinstate the personal. Thus, I chose to focus on individual lives, and through an exploration of a small group of participants’ ‘lived’ experiences of the RWAT module, ascertain what it is like to acquire an academic literacy. The key research question is, therefore: What is it like to acquire an academic literacy? The secondary research question is: How is this experience influenced by the mode of delivery in which it occurs? For its conceptual and theoretical framing, this study draws on social literacy theory and phenomenology, the latter as both a philosophy and a methodology. However, although the study has drawn significantly on the phenomenological tradition for inspiration and direction, it has not done so uncritically. Thus, the study engages with phenomenology-as-philosophy in great depth before turning to phenomenology-as-methodology, in order to arrive at a point where the methods and procedures applied in it, are justified. The main findings of the study suggest that, despite the RWAT module espousing an ideological model (Street, 1984) of literacy in its learning materials and readings, participants came very much closer to experiencing an autonomous model of literacy (Street, 1984). The data shows that the RWAT module was largely inadequate to the task of inducting participants into the ‘situated practices’ and ‘situated meanings’ of the Discourse of Genre Theory and/or the academy, hence the many ‘lived’ difficulties participants experienced. The data also highlights the ease with which an autonomous model of literacy can come to govern practice and student experience even when curriculum intention is underpinned by an ideological position on literacy as social practice. Finally, the study suggests that the research community in South Africa, characterised as it is by such diversity, would be enriched by more studies derived from phenomenology, and a continuing engagement with phenomenology-as-a-movement in order to both challenge and expand its existing framework.
- Full Text:
- Date Issued: 2008
Characterization of a succession of small insect viruses in a wild South African population of Nudaurelia cytherea capensis (Lepidoptera: Saturniidae)
- Walter, Cheryl T, Tomasicchio, Michelle, Hodgson, V, Hendry, Donald A, Hill, Martin P, Dorrington, Rosemary A
- Authors: Walter, Cheryl T , Tomasicchio, Michelle , Hodgson, V , Hendry, Donald A , Hill, Martin P , Dorrington, Rosemary A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6474 , http://hdl.handle.net/10962/d1006161 , http://www.scielo.org.za/scielo.php?pid=S0038-23532008000200015&script=sci_arttext
- Description: The Tetraviridae are a family of small insect RNA viruses first discovered in South Africa some 40 years ago. They consist of one or two single-stranded (+) RNAs encapsidated in an icosahedral capsid of approximately 40 nm in diameter, with T = 4 symmetry. The type members of the two genera within this family, Nudaurelia β virus (NβV) and Nudaurelia ω virus (NωV), infect Nudaurelia cytherea capensis (pine emperor moth) larvae. The absence of N. capensis laboratory colonies and tissue culture cell lines susceptible to virus infection have limited research on the biology of NβV and NωV because the availability of infectious virus is dependent upon sporadic outbreaks in the wild N. capensis populations. In September 2002, dead and dying N. capensis larvae exhibiting symptoms similar to those reported previously in other tetravirus infections were observed in a wild population in a pine forest in the Western Cape province of South Africa. We report here the isolation of three small insect viruses from this population over a period of three years. Transmission electron microscopy and serological characterization indicate that all three are tetra-like virus isolates. One isolate was shown by cDNA sequence analysis to be NβV, which was thought to have been extinct since 1985. The two other isolates are likely new tetraviruses, designated Nudaurelia ψ virus (NψV) and Nudaurelia ζ virus (NζV), which are morphologically and serologically related to NωV and NβV, respectively.
- Full Text:
- Date Issued: 2008
- Authors: Walter, Cheryl T , Tomasicchio, Michelle , Hodgson, V , Hendry, Donald A , Hill, Martin P , Dorrington, Rosemary A
- Date: 2008
- Language: English
- Type: Article
- Identifier: vital:6474 , http://hdl.handle.net/10962/d1006161 , http://www.scielo.org.za/scielo.php?pid=S0038-23532008000200015&script=sci_arttext
- Description: The Tetraviridae are a family of small insect RNA viruses first discovered in South Africa some 40 years ago. They consist of one or two single-stranded (+) RNAs encapsidated in an icosahedral capsid of approximately 40 nm in diameter, with T = 4 symmetry. The type members of the two genera within this family, Nudaurelia β virus (NβV) and Nudaurelia ω virus (NωV), infect Nudaurelia cytherea capensis (pine emperor moth) larvae. The absence of N. capensis laboratory colonies and tissue culture cell lines susceptible to virus infection have limited research on the biology of NβV and NωV because the availability of infectious virus is dependent upon sporadic outbreaks in the wild N. capensis populations. In September 2002, dead and dying N. capensis larvae exhibiting symptoms similar to those reported previously in other tetravirus infections were observed in a wild population in a pine forest in the Western Cape province of South Africa. We report here the isolation of three small insect viruses from this population over a period of three years. Transmission electron microscopy and serological characterization indicate that all three are tetra-like virus isolates. One isolate was shown by cDNA sequence analysis to be NβV, which was thought to have been extinct since 1985. The two other isolates are likely new tetraviruses, designated Nudaurelia ψ virus (NψV) and Nudaurelia ζ virus (NζV), which are morphologically and serologically related to NωV and NβV, respectively.
- Full Text:
- Date Issued: 2008
Characterization of polarization dependent loss in optical fibres and optical components in the presence of polarization mode dispersion
- Authors: Pelaelo, Gaoboelwe
- Date: 2008
- Subjects: Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10528 , http://hdl.handle.net/10948/695 , Fiber optics , Polarization (Light)
- Description: In this study, the Jones matrix eigenanalysis (JME), optical spectrum analyzer (OSA) and polarization scrambling methods were used to investigate polarization dependent loss (PDL) in the presence of polarization mode dispersion (PMD) in optical components and fibres. The PDL measurements were conducted both in the laboratory and in the field. For field measurements, a buried link (28.8 km) and an aerial fibre (7.1 km) were extensively studied. The findings obtained from these studies are very important for network operators who must assess the impact of PDL on the network reliability. The three different PDL measurement methods (JME, OSA and polarization scrambling) were compared and their PDL values were found to agree very well at the selected wavelength of 1550 nm. Concatenation of PDL components showed that as expected, PDL increase as the number of PDL components were added. The interactions between PMD and PDL measurements were analyzed. A PMD/PDL emulator was constructed. We observed that PMD decreased while PDL increased. The PMD decrease was a result of the PMD vector cancellation enhanced by the randomly distributed mode coupling angles while PDL increase was a result of each PM fibre segments contributing to the overall global PDL. It was observed that the presence of PMD in a link containing PDL, results in PDL being wavelength dependent and this resulted in the extraction of the PMD information from the PDL data. PDL was found to be Maxwellian distributed when considering low values of PMD. High PMD values resulted in the PDL distribution deviating from Maxwellian. Long-term PDL and PMD (average DGD) measurements indicated that the PDL and PMD varied slowly with time and wavelength for both the laboratory and field measurements. It was observed that the BER increase as both PDL and PMD increased for simulated optical link.
- Full Text:
- Date Issued: 2008
- Authors: Pelaelo, Gaoboelwe
- Date: 2008
- Subjects: Fiber optics , Polarization (Light)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10528 , http://hdl.handle.net/10948/695 , Fiber optics , Polarization (Light)
- Description: In this study, the Jones matrix eigenanalysis (JME), optical spectrum analyzer (OSA) and polarization scrambling methods were used to investigate polarization dependent loss (PDL) in the presence of polarization mode dispersion (PMD) in optical components and fibres. The PDL measurements were conducted both in the laboratory and in the field. For field measurements, a buried link (28.8 km) and an aerial fibre (7.1 km) were extensively studied. The findings obtained from these studies are very important for network operators who must assess the impact of PDL on the network reliability. The three different PDL measurement methods (JME, OSA and polarization scrambling) were compared and their PDL values were found to agree very well at the selected wavelength of 1550 nm. Concatenation of PDL components showed that as expected, PDL increase as the number of PDL components were added. The interactions between PMD and PDL measurements were analyzed. A PMD/PDL emulator was constructed. We observed that PMD decreased while PDL increased. The PMD decrease was a result of the PMD vector cancellation enhanced by the randomly distributed mode coupling angles while PDL increase was a result of each PM fibre segments contributing to the overall global PDL. It was observed that the presence of PMD in a link containing PDL, results in PDL being wavelength dependent and this resulted in the extraction of the PMD information from the PDL data. PDL was found to be Maxwellian distributed when considering low values of PMD. High PMD values resulted in the PDL distribution deviating from Maxwellian. Long-term PDL and PMD (average DGD) measurements indicated that the PDL and PMD varied slowly with time and wavelength for both the laboratory and field measurements. It was observed that the BER increase as both PDL and PMD increased for simulated optical link.
- Full Text:
- Date Issued: 2008