A molecular analysis of the Afrotropical Baetidae
- Gattolliat, J L, Monaghan, M T, Sartori, Michel, Elouard, J M, Barber-James, Helen M, Derleth, P, Glaizot, Olivier, De Moor, Ferdy C, Vogler, Alfred P
- Authors: Gattolliat, J L , Monaghan, M T , Sartori, Michel , Elouard, J M , Barber-James, Helen M , Derleth, P , Glaizot, Olivier , De Moor, Ferdy C , Vogler, Alfred P
- Date: 2008
- Language: English
- Type: Text
- Identifier: vital:528 , http://hdl.handle.net/10962/d1008393
- Description: Recent work on the Afrotropical Baetidae has resulted in a number of important taxonomic changes: several polyphyletic genera have been split and more than 30 new Afrotropical genera have been established. In order to test their phylogenetic relevance and to clarify the suprageneric relationships, we reconstructed the first comprehensive molecular phylogeny of the Afrotropical Baetidae. We sequenced a total of ca. 2300 bp from nuclear (18S) and mitochondrial (12S and 16S) gene regions from 65 species belonging to 26 genera. We used three different approaches of phylogeny reconstruction: direct optimization, maximum parsimony and maximum likelihood. The molecular reconstruction indicates the Afrotropical Baetidae require a global revision at a generic as well as suprageneric level. Only four of the 12 genera were monophyletic when represented by more than one species in the analysis. Historically, two conflicting concepts of the suprageneric classification of Afrotropical Baetidae were proposed. One was based on the gathering of sister genera into complexes and the other on the division of the family into a restricted number of subfamilies. According to our reconstruction, neither is completely satisfactory: the major complexes of genera present in Africa are either paraphyletic or polyphyletic and the division of the Afrotropical Baetidae into two subfamilies is probably too simplified.
- Full Text:
- Date Issued: 2008
- Authors: Gattolliat, J L , Monaghan, M T , Sartori, Michel , Elouard, J M , Barber-James, Helen M , Derleth, P , Glaizot, Olivier , De Moor, Ferdy C , Vogler, Alfred P
- Date: 2008
- Language: English
- Type: Text
- Identifier: vital:528 , http://hdl.handle.net/10962/d1008393
- Description: Recent work on the Afrotropical Baetidae has resulted in a number of important taxonomic changes: several polyphyletic genera have been split and more than 30 new Afrotropical genera have been established. In order to test their phylogenetic relevance and to clarify the suprageneric relationships, we reconstructed the first comprehensive molecular phylogeny of the Afrotropical Baetidae. We sequenced a total of ca. 2300 bp from nuclear (18S) and mitochondrial (12S and 16S) gene regions from 65 species belonging to 26 genera. We used three different approaches of phylogeny reconstruction: direct optimization, maximum parsimony and maximum likelihood. The molecular reconstruction indicates the Afrotropical Baetidae require a global revision at a generic as well as suprageneric level. Only four of the 12 genera were monophyletic when represented by more than one species in the analysis. Historically, two conflicting concepts of the suprageneric classification of Afrotropical Baetidae were proposed. One was based on the gathering of sister genera into complexes and the other on the division of the family into a restricted number of subfamilies. According to our reconstruction, neither is completely satisfactory: the major complexes of genera present in Africa are either paraphyletic or polyphyletic and the division of the Afrotropical Baetidae into two subfamilies is probably too simplified.
- Full Text:
- Date Issued: 2008
Strategies for retaining talented staff and knowledge managers : a case study
- Authors: Gatyeni, Litha
- Date: 2008
- Subjects: Employee retention -- South Africa , Employee motivation -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8710 , http://hdl.handle.net/10948/958 , Employee retention -- South Africa , Employee motivation -- South Africa
- Description: The South African government is currently targeting 6 per cent economic growth for the country (Mail & Guardian, 2006). The construction industry is one of the growing forces contributing to the current economic growth of South Africa. However, in the speech made by the president Thabo Mbeki, he highlighted the labour market as one of the key constraints to achieving higher and sustainable growth. It is believed that there is a skills shortage or a mismatch in the labour market (Mail & Guardian, 2006). The construction industry has seen a steady growth over the past number of years. When South Africa won the bid to host the 2010 world cup, this required more building work to be done, such as construction of stadia, hotels, etc. This has put further strain in the construction industry. As the work load increases, the companies in the industry require more resources, with the human resources being the most affected. This has seen a high rate of talented staff turnover in the industry as companies seek to increase their capacity to allow them cope with the current work load. The consulting engineering industry plays a critical role of the construction industry. The selected company is part of the electrical and mechanical consulting engineering industry which has also been affected by the high talented staff turnover. The main purpose for this research was to identify retention strategies that can be used by the selected company to reduce the turnover of their talented staff. The research also investigated methods to retain the knowledge within the company that was possibly lost due to a high talented staff turnover rate. The first step used to resolve the issues discussed above was to complete a full literature study. The literature study sought to reveal what characteristics were required in the company that ensured staff would be happy in that company and remain there for a long time. The literature study also covered what knowledge iv management methods can be used by the company to retain its valuable knowledge. Secondly, the views of current staff, ex-staff and management of the selected company on staff and knowledge management strategies were asked in an empirical study, which involved completing questionnaires and conducting structured interviews. Based on the findings of the literature study and the empirical study, the last step was to make recommendations on what strategies should be implemented to retain staff and knowledge for the selected company.
- Full Text:
- Date Issued: 2008
- Authors: Gatyeni, Litha
- Date: 2008
- Subjects: Employee retention -- South Africa , Employee motivation -- South Africa
- Language: English
- Type: Thesis , Masters , MBA
- Identifier: vital:8710 , http://hdl.handle.net/10948/958 , Employee retention -- South Africa , Employee motivation -- South Africa
- Description: The South African government is currently targeting 6 per cent economic growth for the country (Mail & Guardian, 2006). The construction industry is one of the growing forces contributing to the current economic growth of South Africa. However, in the speech made by the president Thabo Mbeki, he highlighted the labour market as one of the key constraints to achieving higher and sustainable growth. It is believed that there is a skills shortage or a mismatch in the labour market (Mail & Guardian, 2006). The construction industry has seen a steady growth over the past number of years. When South Africa won the bid to host the 2010 world cup, this required more building work to be done, such as construction of stadia, hotels, etc. This has put further strain in the construction industry. As the work load increases, the companies in the industry require more resources, with the human resources being the most affected. This has seen a high rate of talented staff turnover in the industry as companies seek to increase their capacity to allow them cope with the current work load. The consulting engineering industry plays a critical role of the construction industry. The selected company is part of the electrical and mechanical consulting engineering industry which has also been affected by the high talented staff turnover. The main purpose for this research was to identify retention strategies that can be used by the selected company to reduce the turnover of their talented staff. The research also investigated methods to retain the knowledge within the company that was possibly lost due to a high talented staff turnover rate. The first step used to resolve the issues discussed above was to complete a full literature study. The literature study sought to reveal what characteristics were required in the company that ensured staff would be happy in that company and remain there for a long time. The literature study also covered what knowledge iv management methods can be used by the company to retain its valuable knowledge. Secondly, the views of current staff, ex-staff and management of the selected company on staff and knowledge management strategies were asked in an empirical study, which involved completing questionnaires and conducting structured interviews. Based on the findings of the literature study and the empirical study, the last step was to make recommendations on what strategies should be implemented to retain staff and knowledge for the selected company.
- Full Text:
- Date Issued: 2008
The career development of low socioeconomic status black South African adolescents: a career systems perspective
- Authors: Geijsendorpher, Clare
- Date: 2008
- Subjects: Blacks -- Education -- South Africa , Education and state -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9920 , http://hdl.handle.net/10948/670 , Blacks -- Education -- South Africa , Education and state -- South Africa , Vocational guidance -- South Africa
- Description: The adolescent stage of development entails many overt and covert challenges and influences that have bearing on spheres of later life, including career development. With South African counsellors being largely dependent on Western career theories, the influence of contextual factors such as cultural beliefs and historical background on the career development of South African adolescents has been largely ignored. The recent acknowledgement of the unique and complex interrelationship between individuals and their specific social, environmental and societal context has motivated the development of an overarching theoretical framework of career development, the Systems Theory Framework (STF). The present study has therefore employed the STF and a qualitative career assessment measure, the My System of Career Influences (MSCI), to facilitate in exploring and describing the unique systems of career influence on the career development of a group of South African adolescents. A non-probability, purposive sampling technique was employed to obtain the sample from a co-educational, Xhosa-speaking secondary school situated in a low socioeconomic area. The research approach was exploratory and descriptive in nature, and the MSCI assisted in the collection of qualitative and quantitative data from a sample of 64 Grade 9, 10 and 11 female and male black adolescents from low socioeconomic status environments. The qualitative data was subjected to content analysis to identify themes, while frequency counts/percentages were used for the quantitative data. The results of the study indicate that all influences within the three interrelated career systems have an influence on the career development of black adolescents. Furthermore, the MSCI workbook was shown to assist participants in identifying and evaluating significant systemic influences that have contributed to their career development to date. Participants from both genders and all grade levels were able to successfully complete the MSCI workbook and provide reflective comments on their MSCI personalised diagrams. The applicability of both the STF and the MSCI are acknowledged. Limitations and recommendations for future research based on the present findings are suggested.
- Full Text:
- Date Issued: 2008
- Authors: Geijsendorpher, Clare
- Date: 2008
- Subjects: Blacks -- Education -- South Africa , Education and state -- South Africa , Vocational guidance -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9920 , http://hdl.handle.net/10948/670 , Blacks -- Education -- South Africa , Education and state -- South Africa , Vocational guidance -- South Africa
- Description: The adolescent stage of development entails many overt and covert challenges and influences that have bearing on spheres of later life, including career development. With South African counsellors being largely dependent on Western career theories, the influence of contextual factors such as cultural beliefs and historical background on the career development of South African adolescents has been largely ignored. The recent acknowledgement of the unique and complex interrelationship between individuals and their specific social, environmental and societal context has motivated the development of an overarching theoretical framework of career development, the Systems Theory Framework (STF). The present study has therefore employed the STF and a qualitative career assessment measure, the My System of Career Influences (MSCI), to facilitate in exploring and describing the unique systems of career influence on the career development of a group of South African adolescents. A non-probability, purposive sampling technique was employed to obtain the sample from a co-educational, Xhosa-speaking secondary school situated in a low socioeconomic area. The research approach was exploratory and descriptive in nature, and the MSCI assisted in the collection of qualitative and quantitative data from a sample of 64 Grade 9, 10 and 11 female and male black adolescents from low socioeconomic status environments. The qualitative data was subjected to content analysis to identify themes, while frequency counts/percentages were used for the quantitative data. The results of the study indicate that all influences within the three interrelated career systems have an influence on the career development of black adolescents. Furthermore, the MSCI workbook was shown to assist participants in identifying and evaluating significant systemic influences that have contributed to their career development to date. Participants from both genders and all grade levels were able to successfully complete the MSCI workbook and provide reflective comments on their MSCI personalised diagrams. The applicability of both the STF and the MSCI are acknowledged. Limitations and recommendations for future research based on the present findings are suggested.
- Full Text:
- Date Issued: 2008
A model to improve the effectiveness of the Occupational Health and Safety Inspectorate function relative to South African construction
- Authors: Geminiani, Franco Luciano
- Date: 2008
- Subjects: Construction industry -- Safety measures
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9695 , http://hdl.handle.net/10948/719 , Construction industry -- Safety measures
- Description: Irrespective of all the efforts made by the Department of Labour (DoL) and other relevant stakeholders to improve the performance of Occupational Health and Safety (OH&S) in construction. In the Construction Industry, there is still a very high level of accidents and fatalities in South Africa. Injuries and accidents to workers do not help a community in any nation. The construction industry in South Africa is generally known to be one of the most hazardous and has one of the most dismal OH&S records among all industrial segments with an unacceptably high level of injuries and fatalities resulting in considerable human suffering. A doctoral study was recently conducted with the aim of investigating the effectiveness and performance of the DoL OH&S Inspectorate in South Africa. The empirical study was conducted among a range of stakeholders: civil engineering and building contractors; OH&S consultants; project managers; DoL inspectors; and designers by means of a questionnaire survey. The methodology adopted in this study included the exploratory and descriptive methods, which entails the technique of observation including the use of questionnaires and data analysis. The salient findings of the study are presented and elucidate that the DoL OH&S Inspectorate is not effective in terms of OH&S relative to the construction industry in South Africa. Conclusions and recommendations included expound that the DoL OH&S Inspectorate is not effectively conducting their duties reinforcing the need for a reviewed OH&S Inspectorate model framework. The proposed structured normative model consists of fundamental elements which would improve the effectiveness of the DoL OH&S Inspectorate. The findings of the study with recommendations are included.
- Full Text:
- Date Issued: 2008
- Authors: Geminiani, Franco Luciano
- Date: 2008
- Subjects: Construction industry -- Safety measures
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9695 , http://hdl.handle.net/10948/719 , Construction industry -- Safety measures
- Description: Irrespective of all the efforts made by the Department of Labour (DoL) and other relevant stakeholders to improve the performance of Occupational Health and Safety (OH&S) in construction. In the Construction Industry, there is still a very high level of accidents and fatalities in South Africa. Injuries and accidents to workers do not help a community in any nation. The construction industry in South Africa is generally known to be one of the most hazardous and has one of the most dismal OH&S records among all industrial segments with an unacceptably high level of injuries and fatalities resulting in considerable human suffering. A doctoral study was recently conducted with the aim of investigating the effectiveness and performance of the DoL OH&S Inspectorate in South Africa. The empirical study was conducted among a range of stakeholders: civil engineering and building contractors; OH&S consultants; project managers; DoL inspectors; and designers by means of a questionnaire survey. The methodology adopted in this study included the exploratory and descriptive methods, which entails the technique of observation including the use of questionnaires and data analysis. The salient findings of the study are presented and elucidate that the DoL OH&S Inspectorate is not effective in terms of OH&S relative to the construction industry in South Africa. Conclusions and recommendations included expound that the DoL OH&S Inspectorate is not effectively conducting their duties reinforcing the need for a reviewed OH&S Inspectorate model framework. The proposed structured normative model consists of fundamental elements which would improve the effectiveness of the DoL OH&S Inspectorate. The findings of the study with recommendations are included.
- Full Text:
- Date Issued: 2008
Agathis bishopi (Nixon) (Hymenoptera: braconidae) its biology and usefulness as a biological control agent for false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: tortricidae), on citrus bishopi (Nixon) (Hymenoptera: braconidae) its biology and usefulness as a biological control agent for false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: tortricidae), on citrus
- Authors: Gendall, Kierryn Leigh
- Date: 2008
- Subjects: Cryptophlebia leucotreta -- Parasites , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Tortricidae , Braconidae , Citrus -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5635 , http://hdl.handle.net/10962/d1005317 , Cryptophlebia leucotreta -- Parasites , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Tortricidae , Braconidae , Citrus -- Diseases and pests
- Description: The false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is one of the major pests of citrus in South Africa, the others being mealybug, Mediterranean fruit fly, bollworm and some mites. Due to problems such as the expense of pesticides, insects evolving pesticide resistance (Hogsette 1999), chemical residue on the skin of export fruit and the negative impact of pesticides on the environment, it became necessary to find alternative methods for pest control (Viggiani 2000). Agathis bishopi (Nixon) (Hymenoptera: Braconidae), a larval parasitoid of false codling moth known only from the Sundays River Valley area (Sishuba 2003), offers a means of control for the pest. A total of 11 389 navel oranges were collected from various orchards in the Addo/Kirkwood area, and false codling moth larvae infested 36.09% of the fruit. A single parasitoid species, A. bishopi, was reared from these larvae. In 2006 the highest parasitism rate, 11.43%, was recorded in May and in 2007, the highest parasitism rate, 13.27%, was in April. Agathis bishopi parasitizes larvae in instars 2 and 3, possibly due to the accessibility of these younger instars to the female parasitoid and possibly due to the length of the life cycle of this koinobiont. Second instar hosts yielded the highest number of parasitoids, and there was no emergence of parasitoids from fifth instar larvae. Females of A. bishopi live for 18.5 days (n = 20; S.E. = 3.1) and males for 8.25 days (n = 20; S.E. = 1.23). Females produce an average of 23 offspring in a lifetime, while female false codling moths produce about 800 eggs each. A high number of parasitoids will be required per hectare to reduce the population of false codling moth. Captive rearing of A. bishopi proved difficult due to viral and fungal contamination. Agathis bishopi has potential for use in an integrated pest management programme once the hurdle of mass-rearing has been overcome.
- Full Text:
- Date Issued: 2008
- Authors: Gendall, Kierryn Leigh
- Date: 2008
- Subjects: Cryptophlebia leucotreta -- Parasites , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Tortricidae , Braconidae , Citrus -- Diseases and pests
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5635 , http://hdl.handle.net/10962/d1005317 , Cryptophlebia leucotreta -- Parasites , Cryptophlebia leucotreta -- Control , Pests -- Biological control , Tortricidae , Braconidae , Citrus -- Diseases and pests
- Description: The false codling moth, Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is one of the major pests of citrus in South Africa, the others being mealybug, Mediterranean fruit fly, bollworm and some mites. Due to problems such as the expense of pesticides, insects evolving pesticide resistance (Hogsette 1999), chemical residue on the skin of export fruit and the negative impact of pesticides on the environment, it became necessary to find alternative methods for pest control (Viggiani 2000). Agathis bishopi (Nixon) (Hymenoptera: Braconidae), a larval parasitoid of false codling moth known only from the Sundays River Valley area (Sishuba 2003), offers a means of control for the pest. A total of 11 389 navel oranges were collected from various orchards in the Addo/Kirkwood area, and false codling moth larvae infested 36.09% of the fruit. A single parasitoid species, A. bishopi, was reared from these larvae. In 2006 the highest parasitism rate, 11.43%, was recorded in May and in 2007, the highest parasitism rate, 13.27%, was in April. Agathis bishopi parasitizes larvae in instars 2 and 3, possibly due to the accessibility of these younger instars to the female parasitoid and possibly due to the length of the life cycle of this koinobiont. Second instar hosts yielded the highest number of parasitoids, and there was no emergence of parasitoids from fifth instar larvae. Females of A. bishopi live for 18.5 days (n = 20; S.E. = 3.1) and males for 8.25 days (n = 20; S.E. = 1.23). Females produce an average of 23 offspring in a lifetime, while female false codling moths produce about 800 eggs each. A high number of parasitoids will be required per hectare to reduce the population of false codling moth. Captive rearing of A. bishopi proved difficult due to viral and fungal contamination. Agathis bishopi has potential for use in an integrated pest management programme once the hurdle of mass-rearing has been overcome.
- Full Text:
- Date Issued: 2008
Towards understanding the mechanism of dimerisation of Saccharomyces cerevisiae eukaryotic translation initiation factor 5A
- Authors: Gentz, Petra Monika
- Date: 2008
- Subjects: Cytology Molecular biology Biochemistry Proteins -- Analysis Proteomics Polypeptides Amino acids -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3992 , http://hdl.handle.net/10962/d1004052
- Description: Eukaryotic translation initiation factor 5A (eIF5A) is the only known protein to contain hypusine, formed by post-translational modification of a highly conserved lysine residue. Hypusination is essential for eIF5A function, being required for binding of a specific subset of mRNAs necessary for progression of eukaryotic cells through the G1-S checkpoint. Little structural information is available for eIF5A other than that derived from archaeal homologues. The aim of this study was to conduct structure-function studies on Saccharomyces cerevisiae (yeast) eIF5A, encoded by TIF51A. Homology models of eIF5A were generated from the Methanococcus jannaschii archaeal homologue (aIF5A) and two Leishmania eIF5As. The models, along with secondary structure predictions identified an a-helix on the C-terminal domain, unique to eukaryote eIF5A. The Neurospora crassa structural analogue, HEX-1, which dimerises in three configurations, was used to generate similar dimeric model configurations of eIF5A. A biochemical and functional analysis was used to validate the homology models of eIF5A.Since the crystal structures of aIF5A and eIF5A were solved from unhypusinated protein produced in Escherichia coli, 6 x His-tagged eIF5A (His-eIF5A) was used for biochemical analysis. This analysis revealed that eIF5A existed as a dimer in solution, dependent on the presence of the highly conserved Cys 39 residue. A yeast TIF51A/TIF51B null yeast strain, with a chromosomal copy of TIF51A under control of PGAL1, was used to confirm that HiseIF5A and selected eIF5A mutants were functional in vivo. Biochemical analysis showed that hypusinated His-eIF5A also exists as a dimer, but neither the dimerisation, nor the function of eIF5A are dependent on the presence of Cys 39. Rather they depend on the presence of hypusine (Hpu) 51 and the presence of RNA leading to the conclusion that RNA and hypusine are required for dimerisation and hence function, of native eIF5A in vivo. In contrast, a Lys 51 to Arg 51 substitution or RNase treatment of His-eIF5A produced in E. coli did not destabilize the dimeric form, suggesting different folding/dimerisation mechanisms in E. coli and yeast cells. The information obtained from the initial homology models, together with the results of the biochemical analysis was used to propose a mechanism for dimerisation of yeast eIF5A involving both hypusine and RNA.
- Full Text:
- Date Issued: 2008
- Authors: Gentz, Petra Monika
- Date: 2008
- Subjects: Cytology Molecular biology Biochemistry Proteins -- Analysis Proteomics Polypeptides Amino acids -- Synthesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3992 , http://hdl.handle.net/10962/d1004052
- Description: Eukaryotic translation initiation factor 5A (eIF5A) is the only known protein to contain hypusine, formed by post-translational modification of a highly conserved lysine residue. Hypusination is essential for eIF5A function, being required for binding of a specific subset of mRNAs necessary for progression of eukaryotic cells through the G1-S checkpoint. Little structural information is available for eIF5A other than that derived from archaeal homologues. The aim of this study was to conduct structure-function studies on Saccharomyces cerevisiae (yeast) eIF5A, encoded by TIF51A. Homology models of eIF5A were generated from the Methanococcus jannaschii archaeal homologue (aIF5A) and two Leishmania eIF5As. The models, along with secondary structure predictions identified an a-helix on the C-terminal domain, unique to eukaryote eIF5A. The Neurospora crassa structural analogue, HEX-1, which dimerises in three configurations, was used to generate similar dimeric model configurations of eIF5A. A biochemical and functional analysis was used to validate the homology models of eIF5A.Since the crystal structures of aIF5A and eIF5A were solved from unhypusinated protein produced in Escherichia coli, 6 x His-tagged eIF5A (His-eIF5A) was used for biochemical analysis. This analysis revealed that eIF5A existed as a dimer in solution, dependent on the presence of the highly conserved Cys 39 residue. A yeast TIF51A/TIF51B null yeast strain, with a chromosomal copy of TIF51A under control of PGAL1, was used to confirm that HiseIF5A and selected eIF5A mutants were functional in vivo. Biochemical analysis showed that hypusinated His-eIF5A also exists as a dimer, but neither the dimerisation, nor the function of eIF5A are dependent on the presence of Cys 39. Rather they depend on the presence of hypusine (Hpu) 51 and the presence of RNA leading to the conclusion that RNA and hypusine are required for dimerisation and hence function, of native eIF5A in vivo. In contrast, a Lys 51 to Arg 51 substitution or RNase treatment of His-eIF5A produced in E. coli did not destabilize the dimeric form, suggesting different folding/dimerisation mechanisms in E. coli and yeast cells. The information obtained from the initial homology models, together with the results of the biochemical analysis was used to propose a mechanism for dimerisation of yeast eIF5A involving both hypusine and RNA.
- Full Text:
- Date Issued: 2008
An assessment of the accelerated professional trade competency development programme within the department of public works in the province of the Eastern Cape
- Authors: George, Thembakazi Caroline
- Date: 2008
- Subjects: Construction workers -- Training of -- South Africa , Skilled labor -- South Africa -- Eastern Cape , Construction workers -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:8223 , http://hdl.handle.net/10948/959 , Construction workers -- Training of -- South Africa , Skilled labor -- South Africa -- Eastern Cape , Construction workers -- South Africa -- Eastern Cape
- Description: In an attempt to address the challenges relating to the lack of well-trained and skilled workers, which directly impacts on the quality of products delivered by the construction sector, this study focuses on an assessment of the Accelerated Professional Trade Competency Development Programme within the Department of Public Works in the province of the Eastern Cape in South Africa. The main focal area of the study is the OR Tambo Region. These challenges manifest themselves through, among others, backlogs in the delivery of housing by the Eastern Cape Department of Housing and Local Government where the majority of houses demonstrate poor workmanship. Hence the Department of Public works has introduced the Accelerated Professional Trade Competency Development Programme. This study investigates the effectiveness of the implementation of the Accelerated Professional Trade Competency Development Programme. Particular attention is paid to the extent to which the Programme contributes towards the development of qualified artisans and what improvement areas can be effected to achieve its objectives.
- Full Text:
- Date Issued: 2008
- Authors: George, Thembakazi Caroline
- Date: 2008
- Subjects: Construction workers -- Training of -- South Africa , Skilled labor -- South Africa -- Eastern Cape , Construction workers -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MPA
- Identifier: vital:8223 , http://hdl.handle.net/10948/959 , Construction workers -- Training of -- South Africa , Skilled labor -- South Africa -- Eastern Cape , Construction workers -- South Africa -- Eastern Cape
- Description: In an attempt to address the challenges relating to the lack of well-trained and skilled workers, which directly impacts on the quality of products delivered by the construction sector, this study focuses on an assessment of the Accelerated Professional Trade Competency Development Programme within the Department of Public Works in the province of the Eastern Cape in South Africa. The main focal area of the study is the OR Tambo Region. These challenges manifest themselves through, among others, backlogs in the delivery of housing by the Eastern Cape Department of Housing and Local Government where the majority of houses demonstrate poor workmanship. Hence the Department of Public works has introduced the Accelerated Professional Trade Competency Development Programme. This study investigates the effectiveness of the implementation of the Accelerated Professional Trade Competency Development Programme. Particular attention is paid to the extent to which the Programme contributes towards the development of qualified artisans and what improvement areas can be effected to achieve its objectives.
- Full Text:
- Date Issued: 2008
Electrooxidation of hydrazine catalyzed by noncovalently functionalized single-walled carbon nanotubes with CoPc
- Geraldo, Daniela A, Togo, Chamunorwa A, Limson, Janice, Nyokong, Tebello
- Authors: Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265963 , vital:53904 , xlink:href="https://doi.org/10.1016/j.electacta.2008.05.083"
- Description: We report on the electrooxidation of hydrazine catalyzed by single-walled carbon nanotube (SWCNT) functionalized with cobalt phthalocyanine (CoPc) which shows that the presence of the single-walled carbon nanotubes enhances the catalytic activity of the CoPc itself without any change in the reaction mechanism. A synergistic effect, in terms of reactivity when the new nanocomposite material was adsorbed on the GC electrode, was observed. The obtained hybrid electrodes were tested under hydrodynamic conditions, showing two different oxidation processes, which suggest the presence of two different types of active sites on the electrode surface catalyzing the reaction. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the GC/SWCNT + CoPc showed much lower electron-resistance (Ret) confirming the synergistic effect of the composite mentioned above. Atomic force microscopy (AFM) images showed the clear differences in surface roughness for each film, confirming the different compositions of the hybrid electrodes used in this study.
- Full Text:
- Date Issued: 2008
- Authors: Geraldo, Daniela A , Togo, Chamunorwa A , Limson, Janice , Nyokong, Tebello
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/265963 , vital:53904 , xlink:href="https://doi.org/10.1016/j.electacta.2008.05.083"
- Description: We report on the electrooxidation of hydrazine catalyzed by single-walled carbon nanotube (SWCNT) functionalized with cobalt phthalocyanine (CoPc) which shows that the presence of the single-walled carbon nanotubes enhances the catalytic activity of the CoPc itself without any change in the reaction mechanism. A synergistic effect, in terms of reactivity when the new nanocomposite material was adsorbed on the GC electrode, was observed. The obtained hybrid electrodes were tested under hydrodynamic conditions, showing two different oxidation processes, which suggest the presence of two different types of active sites on the electrode surface catalyzing the reaction. Electrochemical impedance spectroscopy (EIS) analyses in the presence of [Fe(CN)6]3−/4− as a redox probe revealed that the GC/SWCNT + CoPc showed much lower electron-resistance (Ret) confirming the synergistic effect of the composite mentioned above. Atomic force microscopy (AFM) images showed the clear differences in surface roughness for each film, confirming the different compositions of the hybrid electrodes used in this study.
- Full Text:
- Date Issued: 2008
The zonation of coastal dune plants in relation to sand burial, resource availability and physiological adaptation
- Authors: Gilbert, Matthew Edmund
- Date: 2008
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Botany -- South Africa -- Eastern Cape Coastal biology -- South Africa -- Eastern Cape Littoral plants -- South Africa -- Eastern Cape Littoral plants Sand dune plants -- Ecophysiology Sand dune plants -- Geographical distribution
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4195 , http://hdl.handle.net/10962/d1003764
- Description: When considering the large amount of work done on dune ecology, and that a number of the classical ecological theories originate from work on dunes, it is apparent that there remains a need for physiological and mechanistic explanations of dune plant phenomena. This thesis demonstrated that in the extreme coastal environment dune plants must survive both high rates of burial (disturbance), and low nutrient availability (stress). The ability of four species to respond to these two factors corresponded with their position in a vegetation gradient on the dunes. A low stem tissue density was shown to enhance the potential stem elongation rate of buried plants, but reduced the maximum height to which a plant could grow. Such a tradeoff implies that tall light-competitive plants are able to survive only in stable areas, while burial responsive mobile-dune plants are limited to areas of low vegetation height. This stem tissue density tradeoff was suggested as the mechanism determining the zonation that species show within the dune vegetation gradient present at various sites in South Africa. Finally, detailed investigations of dune plant ecophysiology found that: 1) The resources used in the response to burial derive from external sources of carbon and nitrogen, as well as simple physiological and physical mechanisms of resource allocation. 2) The leaves of dune plants were found to be operating at one extreme of the photosynthetic continuum; viz efficient use of leaf nitrogen at the expense of water loss. 3) Contrary to other ecosystems, the environmental characteristics of dunes may allow plants to occupy a high disturbance, high stress niche, through the maintenance of lowered competition. 4) At least two mobile-dune species form steep dunes, and are able to optimise growth, on steeper dunes, such that they have to grow less in response to burial than plants that form more shallow dunes. In this thesis, it was shown that the link between the carbon and nitrogen economies of dune plants was pivotal in determining species distributions and survival under extreme environmental conditions. As vast areas of the world’s surface are covered by sand dunes these observations are not just of passing interest.
- Full Text:
- Date Issued: 2008
- Authors: Gilbert, Matthew Edmund
- Date: 2008
- Subjects: Sand dune conservation -- South Africa -- Eastern Cape Coastal ecology -- South Africa -- Eastern Cape Botany -- South Africa -- Eastern Cape Coastal biology -- South Africa -- Eastern Cape Littoral plants -- South Africa -- Eastern Cape Littoral plants Sand dune plants -- Ecophysiology Sand dune plants -- Geographical distribution
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4195 , http://hdl.handle.net/10962/d1003764
- Description: When considering the large amount of work done on dune ecology, and that a number of the classical ecological theories originate from work on dunes, it is apparent that there remains a need for physiological and mechanistic explanations of dune plant phenomena. This thesis demonstrated that in the extreme coastal environment dune plants must survive both high rates of burial (disturbance), and low nutrient availability (stress). The ability of four species to respond to these two factors corresponded with their position in a vegetation gradient on the dunes. A low stem tissue density was shown to enhance the potential stem elongation rate of buried plants, but reduced the maximum height to which a plant could grow. Such a tradeoff implies that tall light-competitive plants are able to survive only in stable areas, while burial responsive mobile-dune plants are limited to areas of low vegetation height. This stem tissue density tradeoff was suggested as the mechanism determining the zonation that species show within the dune vegetation gradient present at various sites in South Africa. Finally, detailed investigations of dune plant ecophysiology found that: 1) The resources used in the response to burial derive from external sources of carbon and nitrogen, as well as simple physiological and physical mechanisms of resource allocation. 2) The leaves of dune plants were found to be operating at one extreme of the photosynthetic continuum; viz efficient use of leaf nitrogen at the expense of water loss. 3) Contrary to other ecosystems, the environmental characteristics of dunes may allow plants to occupy a high disturbance, high stress niche, through the maintenance of lowered competition. 4) At least two mobile-dune species form steep dunes, and are able to optimise growth, on steeper dunes, such that they have to grow less in response to burial than plants that form more shallow dunes. In this thesis, it was shown that the link between the carbon and nitrogen economies of dune plants was pivotal in determining species distributions and survival under extreme environmental conditions. As vast areas of the world’s surface are covered by sand dunes these observations are not just of passing interest.
- Full Text:
- Date Issued: 2008
The effect of varied instructions on prison guard role behaviour expectations
- Authors: Githaiga, Sandra J N
- Date: 2008
- Subjects: Prison psychology -- Experiments , Role expectations , Imprisonment -- Experiments
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9908 , http://hdl.handle.net/10948/961 , Prison psychology -- Experiments , Role expectations , Imprisonment -- Experiments
- Description: The Stanford Prison Experiment (SPE) was conducted to determine the psychological and behavioural effects of adopting the roles of prisoners or prison guards. In various published research articles Zimbardo reported that he instructed the prison guards to maintain law and order (Haney, Banks, & Zimbardo, 1973). However, in the Quiet Rage video (Zimbardo, 1989), Zimbardo gave the prison guards additional detailed instructions. To examine the effects of these different instructions on expected prison guard role behaviour, first year Psychology students were requested to predict expected prison guard role behaviour under two different conditions. In the order condition, participants received the instructions used in published research articles. While in the fear condition, participants received the instructions from the Quiet Rage video (Zimbardo, 1989). Participants estimated the likelihood of 50 guard behaviours. Participants in the order condition predicted more pleasant behaviour, while participants in the fear condition predicted more unpleasant behaviours. This indicates that the different instructions influenced their intent to perform the different behaviours. There was no significant difference between the fear and order conditions, and the control behaviours. Participants in both the fear and order conditions rated the control items as expected prison guard role behaviour. Participants in both conditions indicated that they would behave in this manner. Gender had no significant influence on expected prison guard role behavior.
- Full Text:
- Date Issued: 2008
- Authors: Githaiga, Sandra J N
- Date: 2008
- Subjects: Prison psychology -- Experiments , Role expectations , Imprisonment -- Experiments
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:9908 , http://hdl.handle.net/10948/961 , Prison psychology -- Experiments , Role expectations , Imprisonment -- Experiments
- Description: The Stanford Prison Experiment (SPE) was conducted to determine the psychological and behavioural effects of adopting the roles of prisoners or prison guards. In various published research articles Zimbardo reported that he instructed the prison guards to maintain law and order (Haney, Banks, & Zimbardo, 1973). However, in the Quiet Rage video (Zimbardo, 1989), Zimbardo gave the prison guards additional detailed instructions. To examine the effects of these different instructions on expected prison guard role behaviour, first year Psychology students were requested to predict expected prison guard role behaviour under two different conditions. In the order condition, participants received the instructions used in published research articles. While in the fear condition, participants received the instructions from the Quiet Rage video (Zimbardo, 1989). Participants estimated the likelihood of 50 guard behaviours. Participants in the order condition predicted more pleasant behaviour, while participants in the fear condition predicted more unpleasant behaviours. This indicates that the different instructions influenced their intent to perform the different behaviours. There was no significant difference between the fear and order conditions, and the control behaviours. Participants in both the fear and order conditions rated the control items as expected prison guard role behaviour. Participants in both conditions indicated that they would behave in this manner. Gender had no significant influence on expected prison guard role behavior.
- Full Text:
- Date Issued: 2008
Jantjie v The Minister of Labour Unreported Eastern Cape Division Case No 2193/2006
- Authors: Glover, Graham B , Beard, M
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186891 , vital:44545 , xlink:href="///C:/Users/User/Downloads/41DeJure648%20(1).pdf"
- Description: James Joyce once wrote that "mistakes ... are the portals of discovery" (Ulysses (1964) Ch 9). This aptly describes the legal significance of the judgment in Jantjie v Minister of Labour (unreported decision of the High Court, Eastern Cape Division, case no 3193/2006, decided on 2007-06- 14). In this case, Leach J had to deal with a matter of civil procedure that does not seem to have been dealt with in any reported judgment - the effect of an attorney of record mistakenly failing to sign a notice of motion where an application is brought before the High Court.
- Full Text:
- Date Issued: 2008
- Authors: Glover, Graham B , Beard, M
- Date: 2008
- Subjects: To be catalogued
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/186891 , vital:44545 , xlink:href="///C:/Users/User/Downloads/41DeJure648%20(1).pdf"
- Description: James Joyce once wrote that "mistakes ... are the portals of discovery" (Ulysses (1964) Ch 9). This aptly describes the legal significance of the judgment in Jantjie v Minister of Labour (unreported decision of the High Court, Eastern Cape Division, case no 3193/2006, decided on 2007-06- 14). In this case, Leach J had to deal with a matter of civil procedure that does not seem to have been dealt with in any reported judgment - the effect of an attorney of record mistakenly failing to sign a notice of motion where an application is brought before the High Court.
- Full Text:
- Date Issued: 2008
"A complex and delicate web" : a comparative study of selected speculative novels by Margaret Atwood, Ursula K. Le Guin, Doris Lessing and Marge Piercy
- Authors: Glover, Jayne Ashleigh
- Date: 2008
- Subjects: Atwood, Margaret Eleanor, 1939- -- Criticism and interpretation Le Guin, Ursula K., 1929- -- Criticism and interpretation Lessing, Doris May, 1919- -- Criticism and interpretation Piercy, Marge Piercy, Marge -- Criticism and interpretation Utopias in literature Dystopias in literature Science fiction, English -- History and criticism Fantasy fiction -- History and criticism Fantasy literature -- History and criticism Women authors -- 20th Century Women authors -- 21st Century English fiction -- 20th Century English fiction -- 21st Century
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2199 , http://hdl.handle.net/10962/d1002241
- Description: This thesis examines selected speculative novels by Margaret Atwood, Ursula K. Le Guin, Doris Lessing and Marge Piercy. It argues that a specifiable ecological ethic can be traced in their work – an ethic which is explored by them through the tensions between utopian and dystopian discourses. The first part of the thesis begins by theorising the concept of an ecological ethic of respect for the Other through current ecological philosophies, such as those developed by Val Plumwood. Thereafter, it contextualises the novels within the broader field of science fiction, and speculative fiction in particular, arguing that the shift from a critical utopian to a critical dystopian style evinces their changing treatment of this ecological ethic within their work. The remainder of the thesis is divided into two parts, each providing close readings of chosen novels in the light of this argument. Part Two provides a reading of Le Guin’s early Hainish novels, The Left Hand of Darkness, The Word for World is Forest and The Dispossessed, followed by an examination of Piercy’s Woman on the Edge of Time, Lessing’s The Marriages Between Zones Three, Four and Five, and Atwood’s The Handmaid’s Tale. The third, and final, part of the thesis consists of individual chapters analysing the later speculative novels of each author. Piercy’s He, She and It, Le Guin’s The Telling, and Atwood’s Oryx and Crake are all scrutinised, as are Lessing’s two recent ‘Ifrik’ novels. This thesis shows, then, that speculative fiction is able to realise through fiction many of the ideals of ecological thinkers. Furthermore, the increasing dystopianism of these novels reflects the greater urgency with which the problem of Othering needs to be addressed in the light of the present global ecological crisis.
- Full Text:
- Date Issued: 2008
- Authors: Glover, Jayne Ashleigh
- Date: 2008
- Subjects: Atwood, Margaret Eleanor, 1939- -- Criticism and interpretation Le Guin, Ursula K., 1929- -- Criticism and interpretation Lessing, Doris May, 1919- -- Criticism and interpretation Piercy, Marge Piercy, Marge -- Criticism and interpretation Utopias in literature Dystopias in literature Science fiction, English -- History and criticism Fantasy fiction -- History and criticism Fantasy literature -- History and criticism Women authors -- 20th Century Women authors -- 21st Century English fiction -- 20th Century English fiction -- 21st Century
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2199 , http://hdl.handle.net/10962/d1002241
- Description: This thesis examines selected speculative novels by Margaret Atwood, Ursula K. Le Guin, Doris Lessing and Marge Piercy. It argues that a specifiable ecological ethic can be traced in their work – an ethic which is explored by them through the tensions between utopian and dystopian discourses. The first part of the thesis begins by theorising the concept of an ecological ethic of respect for the Other through current ecological philosophies, such as those developed by Val Plumwood. Thereafter, it contextualises the novels within the broader field of science fiction, and speculative fiction in particular, arguing that the shift from a critical utopian to a critical dystopian style evinces their changing treatment of this ecological ethic within their work. The remainder of the thesis is divided into two parts, each providing close readings of chosen novels in the light of this argument. Part Two provides a reading of Le Guin’s early Hainish novels, The Left Hand of Darkness, The Word for World is Forest and The Dispossessed, followed by an examination of Piercy’s Woman on the Edge of Time, Lessing’s The Marriages Between Zones Three, Four and Five, and Atwood’s The Handmaid’s Tale. The third, and final, part of the thesis consists of individual chapters analysing the later speculative novels of each author. Piercy’s He, She and It, Le Guin’s The Telling, and Atwood’s Oryx and Crake are all scrutinised, as are Lessing’s two recent ‘Ifrik’ novels. This thesis shows, then, that speculative fiction is able to realise through fiction many of the ideals of ecological thinkers. Furthermore, the increasing dystopianism of these novels reflects the greater urgency with which the problem of Othering needs to be addressed in the light of the present global ecological crisis.
- Full Text:
- Date Issued: 2008
Educators perceived challenges in dealing with HIV and AIDS orphans and vulnerable children
- Authors: Goba, Linda
- Date: 2008
- Subjects: Children of AIDS patients -- Education -- South Africa , Orphans -- Education -- South Africa , Teachers -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9526 , http://hdl.handle.net/10948/963 , Children of AIDS patients -- Education -- South Africa , Orphans -- Education -- South Africa , Teachers -- South Africa -- Attitudes
- Description: The HIV and AIDS pandemic in South Africa has increased the number of orphans and vulnerable children in the school system. Given the prominent role that teachers can play in ensuring that these children receive a quality education so as to maximise their life opportunities, it is important for teachers to be empowered and equipped to enable them to deal with issues surrounding orphans and vulnerable children (OVC) at schools. This study focuses on how teachers are experiencing the impact of HIV and AIDS in schools as a result of having OVC in their classes. The Department of Education has developed training courses to help teachers cope with the impact of HIV and AIDS, but the effectiveness of these programmes has not yet been evaluated. This study aims to establish how teachers who have attended these programmes feel about the assistance rendered to them to deal with OVC related issues. In order to meet this aim, a qualitative enquiry was conducted among a sample of selected teachers from the Eastern Cape. The findings suggest that, while the training has helped to improve the knowledge and attitudes of the teachers, it has not equipped them with the necessary skills to overcome barriers to implement the training programmes at school level. The findings also suggest that there is a need for ongoing support from the Department of Education and the trainers it contracts to ensure that learning from the training is implemented in the schools. Based on the research findings, the study concludes with recommendations that will help teachers to better cope with OVC related issues at school.
- Full Text:
- Date Issued: 2008
- Authors: Goba, Linda
- Date: 2008
- Subjects: Children of AIDS patients -- Education -- South Africa , Orphans -- Education -- South Africa , Teachers -- South Africa -- Attitudes
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:9526 , http://hdl.handle.net/10948/963 , Children of AIDS patients -- Education -- South Africa , Orphans -- Education -- South Africa , Teachers -- South Africa -- Attitudes
- Description: The HIV and AIDS pandemic in South Africa has increased the number of orphans and vulnerable children in the school system. Given the prominent role that teachers can play in ensuring that these children receive a quality education so as to maximise their life opportunities, it is important for teachers to be empowered and equipped to enable them to deal with issues surrounding orphans and vulnerable children (OVC) at schools. This study focuses on how teachers are experiencing the impact of HIV and AIDS in schools as a result of having OVC in their classes. The Department of Education has developed training courses to help teachers cope with the impact of HIV and AIDS, but the effectiveness of these programmes has not yet been evaluated. This study aims to establish how teachers who have attended these programmes feel about the assistance rendered to them to deal with OVC related issues. In order to meet this aim, a qualitative enquiry was conducted among a sample of selected teachers from the Eastern Cape. The findings suggest that, while the training has helped to improve the knowledge and attitudes of the teachers, it has not equipped them with the necessary skills to overcome barriers to implement the training programmes at school level. The findings also suggest that there is a need for ongoing support from the Department of Education and the trainers it contracts to ensure that learning from the training is implemented in the schools. Based on the research findings, the study concludes with recommendations that will help teachers to better cope with OVC related issues at school.
- Full Text:
- Date Issued: 2008
Economic valuation of communal rangelands in the Eastern Cape Province of South Africa
- Authors: Gombakomba, Gift
- Date: 2008
- Subjects: Rangelands -- South Africa -- Eastern Cape -- Evaluation , Rural development -- South Africa -- Eastern Cape -- Evaluation , Commons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11166 , http://hdl.handle.net/10353/351 , Rangelands -- South Africa -- Eastern Cape -- Evaluation , Rural development -- South Africa -- Eastern Cape -- Evaluation , Commons -- South Africa -- Eastern Cape
- Description: The exploitation and conversion of rangeland ecosystems is often explained by economists as being the result of an undervaluation of the goods and services provided by the rangelands. Undervaluation of rangelands may contribute to their mismanagement or their transformation to monoculture, such as livestock or gathering. Similarly, this may lead to inappropriate policy recommendations and prescriptions. This study undertakes a valuation exercise in an effort to address causes of undervaluation. The objective of the study is to estimate the annual direct, indirect and non-use values per household of communal rangelands in the Eastern Cape Province, based on both primary and secondary data. The exercise incorporates the two major direct uses, both marketed and non-marketed, of rangelands - livestock and gathering. Contingent valuation method based on stated preferences by individual household was used to value the indirect and non-use values of the communal rangelands (e.g. erosion protection and burial sites). Data was collected using PRAs, structured questionnaires and interviews by trained enumerators. The study shows that half of the households owned livestock, which is the main economic use of the rangelands and gathering of natural resources also made an economic contribution. Every household was involved in collection of range resources such as fuel wood, wild fruits, thatch grass, building poles, hunting, fishing make a significant contribution to the direct use values: in the case of gathering it shows that there is “hidden harvest” of many of the natural resources from the rangelands. Indirect and non-use values are shown to be important in the communal areas but are difficult to quantify; the results of these are based on qualitative analysis. Keywords: communal rangelands, demand curve, direct use values, indirect use values, individuals’ preferences, non-use values, willingness-to-accept and willingness-to-pay.
- Full Text:
- Date Issued: 2008
- Authors: Gombakomba, Gift
- Date: 2008
- Subjects: Rangelands -- South Africa -- Eastern Cape -- Evaluation , Rural development -- South Africa -- Eastern Cape -- Evaluation , Commons -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Masters , MSc Agric (Agricultural Economics)
- Identifier: vital:11166 , http://hdl.handle.net/10353/351 , Rangelands -- South Africa -- Eastern Cape -- Evaluation , Rural development -- South Africa -- Eastern Cape -- Evaluation , Commons -- South Africa -- Eastern Cape
- Description: The exploitation and conversion of rangeland ecosystems is often explained by economists as being the result of an undervaluation of the goods and services provided by the rangelands. Undervaluation of rangelands may contribute to their mismanagement or their transformation to monoculture, such as livestock or gathering. Similarly, this may lead to inappropriate policy recommendations and prescriptions. This study undertakes a valuation exercise in an effort to address causes of undervaluation. The objective of the study is to estimate the annual direct, indirect and non-use values per household of communal rangelands in the Eastern Cape Province, based on both primary and secondary data. The exercise incorporates the two major direct uses, both marketed and non-marketed, of rangelands - livestock and gathering. Contingent valuation method based on stated preferences by individual household was used to value the indirect and non-use values of the communal rangelands (e.g. erosion protection and burial sites). Data was collected using PRAs, structured questionnaires and interviews by trained enumerators. The study shows that half of the households owned livestock, which is the main economic use of the rangelands and gathering of natural resources also made an economic contribution. Every household was involved in collection of range resources such as fuel wood, wild fruits, thatch grass, building poles, hunting, fishing make a significant contribution to the direct use values: in the case of gathering it shows that there is “hidden harvest” of many of the natural resources from the rangelands. Indirect and non-use values are shown to be important in the communal areas but are difficult to quantify; the results of these are based on qualitative analysis. Keywords: communal rangelands, demand curve, direct use values, indirect use values, individuals’ preferences, non-use values, willingness-to-accept and willingness-to-pay.
- Full Text:
- Date Issued: 2008
A supplementary coping skills programme for parents of children diagnosed with attention deficit hyperactivity disorder
- Authors: Gomes, Ana Maria
- Date: 2008
- Subjects: Attention-deficit-disordered children -- Family relationships , Children with disabilities -- Education
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9471 , http://hdl.handle.net/10948/686
- Description: Attention Deficit Hyperactivity Disorder (ADHD)-related behaviour difficulties are said to be the cause of much of the disharmony and discord that exists within many families with ADHD-diagnosed children. On the basis of this understanding, a supplementary programme of behaviour modification, referred to as the Coping Skills Programme, was designed and implemented over a designated period of time, as a trial efficiency test, with a view to alleviate some of the family environmental stress caused by the effects of this disorder. There were three main aims to this research project, related to the research questions: Firstly, to establish to what extent this programme helped with the kinds of problems and difficulties being experienced by the parents of ADHD-diagnosed children and by the children themselves; secondly, to make recommendations regarding how to access and use such a programme and learn its skills, and thirdly to determine further ways with which to improve the Coping Skills Programme. The research design was based on Interpretive Theory and was qualitative in nature. An in-depth literature study was undertaken, which together with all the field notes acquired during the course of the study, formed the foundation of the study. A needs analysis was also carried out to ascertain the level and variety of ADHD-related needs that exist within the family unit. This needs analysis took place in the Nelson Mandela Metropole in the Eastern Cape to ascertain the level and variety of ADHD-related needs that exist within the family unit. The sampling selection of participants was both purposeful and dependent on availability, in order obtain as wide a range of information as possible, regarding specific ADHD-related criteria. This data was used as a foundation for the programme’s development. Information was gathered by means of phenomenological interviews, case study analysis, a focus group interview, field notes, observations and an audit trail. Measures were taken to ensure that the study was ethically conducted and trustworthiness maintained. The Coping Skills Programme was implemented with different families with ADHD-diagnosed children, within its designated time, which varied from family to family from between 8 and 10 weeks. Finally, three families were xx selected as case studies to substantiate the findings of this research study. Their selection was based on the range of the children’s age, the variety of their combined needs, the way in which each family dealt with the challenges posed by the programme, the parents’ involvement and the rate of success experienced by each family at the end of the allotted time. At the end of the programme’s implementation period it was found that confusion regarding parental role clarity and the role of the child in the home had a strong bearing on the treatment and management of ADHD-related difficulties. It was also found that the effect of parental unity and/or discord had a direct impact on ADHD-related behaviour. Equally important to the effective management of ADHD-related difficulties were the parental understanding and perceptions regarding their child’s ADHD-related needs and difficulties. The effectiveness of behaviour modification in relation to the level of parental involvement was also salient, as was the use of effective, positive communication to achievement of optimum results. Parental understanding of the role of discipline and how the effective use of this skill benefits the ADHD-diagnosed child became clear, as did the value of consistency in behaviour modification. The conclusion was reached that a programme as flexible as the Coping Skills Programme, when used appropriately and as a supplement to other forms of therapy, may be a significant source of assistance, support, encouragement and empowerment to families with members suffering with ADHD.
- Full Text:
- Date Issued: 2008
- Authors: Gomes, Ana Maria
- Date: 2008
- Subjects: Attention-deficit-disordered children -- Family relationships , Children with disabilities -- Education
- Language: English
- Type: Thesis , Doctoral , DEd
- Identifier: vital:9471 , http://hdl.handle.net/10948/686
- Description: Attention Deficit Hyperactivity Disorder (ADHD)-related behaviour difficulties are said to be the cause of much of the disharmony and discord that exists within many families with ADHD-diagnosed children. On the basis of this understanding, a supplementary programme of behaviour modification, referred to as the Coping Skills Programme, was designed and implemented over a designated period of time, as a trial efficiency test, with a view to alleviate some of the family environmental stress caused by the effects of this disorder. There were three main aims to this research project, related to the research questions: Firstly, to establish to what extent this programme helped with the kinds of problems and difficulties being experienced by the parents of ADHD-diagnosed children and by the children themselves; secondly, to make recommendations regarding how to access and use such a programme and learn its skills, and thirdly to determine further ways with which to improve the Coping Skills Programme. The research design was based on Interpretive Theory and was qualitative in nature. An in-depth literature study was undertaken, which together with all the field notes acquired during the course of the study, formed the foundation of the study. A needs analysis was also carried out to ascertain the level and variety of ADHD-related needs that exist within the family unit. This needs analysis took place in the Nelson Mandela Metropole in the Eastern Cape to ascertain the level and variety of ADHD-related needs that exist within the family unit. The sampling selection of participants was both purposeful and dependent on availability, in order obtain as wide a range of information as possible, regarding specific ADHD-related criteria. This data was used as a foundation for the programme’s development. Information was gathered by means of phenomenological interviews, case study analysis, a focus group interview, field notes, observations and an audit trail. Measures were taken to ensure that the study was ethically conducted and trustworthiness maintained. The Coping Skills Programme was implemented with different families with ADHD-diagnosed children, within its designated time, which varied from family to family from between 8 and 10 weeks. Finally, three families were xx selected as case studies to substantiate the findings of this research study. Their selection was based on the range of the children’s age, the variety of their combined needs, the way in which each family dealt with the challenges posed by the programme, the parents’ involvement and the rate of success experienced by each family at the end of the allotted time. At the end of the programme’s implementation period it was found that confusion regarding parental role clarity and the role of the child in the home had a strong bearing on the treatment and management of ADHD-related difficulties. It was also found that the effect of parental unity and/or discord had a direct impact on ADHD-related behaviour. Equally important to the effective management of ADHD-related difficulties were the parental understanding and perceptions regarding their child’s ADHD-related needs and difficulties. The effectiveness of behaviour modification in relation to the level of parental involvement was also salient, as was the use of effective, positive communication to achievement of optimum results. Parental understanding of the role of discipline and how the effective use of this skill benefits the ADHD-diagnosed child became clear, as did the value of consistency in behaviour modification. The conclusion was reached that a programme as flexible as the Coping Skills Programme, when used appropriately and as a supplement to other forms of therapy, may be a significant source of assistance, support, encouragement and empowerment to families with members suffering with ADHD.
- Full Text:
- Date Issued: 2008
Applications of thermal spray technology for surface protection
- Authors: Gorlach, I A
- Subjects: Metal spraying , Surfaces (Technology)
- Language: English
- Type: text , Lectures
- Identifier: http://hdl.handle.net/10948/21866 , vital:29795
- Description: With the rapid development of modern industry, the quality of surfaces of structures, products and components is important in terms of many aspects such as efficiency, reliability, appearance, maintenance costs and economy. A local failure on the surface usually causes the entire component to be rejected or it may lead to a failure of a machine or structure. It is estimated that in developed countries, the loss caused by corrosion is up to 2-4% of gross national product [1]. Thus, many countries have made great efforts to improve the surface performance of parts in order to enhance the reliability of mechanical equipment and prolong their service life.
- Full Text: false
- Authors: Gorlach, I A
- Subjects: Metal spraying , Surfaces (Technology)
- Language: English
- Type: text , Lectures
- Identifier: http://hdl.handle.net/10948/21866 , vital:29795
- Description: With the rapid development of modern industry, the quality of surfaces of structures, products and components is important in terms of many aspects such as efficiency, reliability, appearance, maintenance costs and economy. A local failure on the surface usually causes the entire component to be rejected or it may lead to a failure of a machine or structure. It is estimated that in developed countries, the loss caused by corrosion is up to 2-4% of gross national product [1]. Thus, many countries have made great efforts to improve the surface performance of parts in order to enhance the reliability of mechanical equipment and prolong their service life.
- Full Text: false
An analysis of current East African higher education systems and institutions
- Authors: Gouws, Jeanine
- Date: 2008
- Subjects: Education, Higher -- Africa, East -- Evaluation , Universities and colleges -- Africa, East
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:16147 , http://hdl.handle.net/10948/785 , Education, Higher -- Africa, East -- Evaluation , Universities and colleges -- Africa, East
- Description: Higher education (HE) institutions play a vital role in the generation of new knowledge in the 21st Century, as HE is recognised as a key force for modernisation and development. The development and advancement of information technology have led to an interconnected, borderless world of knowledge, and HE institutions have become part of what is known as the global HE network society. HE institutions in developed countries are the most actively involved in producing and disseminating knowledge, and compete with one another in adding to this world stock of knowledge. In addition, HE has become a national priority in developed countries, and governments place pressure on HE institutions to form part of and remain active in the global HE network society in order to contribute to the knowledge-centred economy of today. However, the developing world lags far behind in becoming part of the global HE network society. As long as the developing world face constraints in attempts to improve national economies, alleviate poverty and maintain sustainability, prospects of contributing to, and participating in the global HE network society seem unlikely. HE can be used as a tool in addressing national development needs. With the necessary support and recognition from governments, HE should play a vital role in the process of reform and the revitalisation of developing countries. Africa is the least developed in terms of HE institutions. Approximately 300 institutions fit the definition of a university across the continent. While some countries on the continent, especially in Southern and Northern Africa, can claim comprehensive academic systems, most have just a few academic institutions and some countries have not yet even established differentiated post-secondary systems. It is generally assumed that most countries south of the Sahara lack adequate HE systems, or that they have no HE systems at all. Very little information on African HE systems and institutions, and how they function, is available, and there is a need for a deeper investigation into African HE systems and institutions. The vastness and diversity of the African continent does not allow for a single study of all African countries and their HE systems and institutions. It is for this reason that East Africa, comprising Kenya, Uganda and Tanzania, was chosen for this study. This specific region exhibits common characteristics amongst its countries. A British colonial history, similar secondary schooling systems and a predominance of the English language, set East Africa apart from the rest of the African continent. East African HE functions on a regional, national, and institutional level, and their way of functioning is interdependent.
- Full Text:
- Date Issued: 2008
- Authors: Gouws, Jeanine
- Date: 2008
- Subjects: Education, Higher -- Africa, East -- Evaluation , Universities and colleges -- Africa, East
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:16147 , http://hdl.handle.net/10948/785 , Education, Higher -- Africa, East -- Evaluation , Universities and colleges -- Africa, East
- Description: Higher education (HE) institutions play a vital role in the generation of new knowledge in the 21st Century, as HE is recognised as a key force for modernisation and development. The development and advancement of information technology have led to an interconnected, borderless world of knowledge, and HE institutions have become part of what is known as the global HE network society. HE institutions in developed countries are the most actively involved in producing and disseminating knowledge, and compete with one another in adding to this world stock of knowledge. In addition, HE has become a national priority in developed countries, and governments place pressure on HE institutions to form part of and remain active in the global HE network society in order to contribute to the knowledge-centred economy of today. However, the developing world lags far behind in becoming part of the global HE network society. As long as the developing world face constraints in attempts to improve national economies, alleviate poverty and maintain sustainability, prospects of contributing to, and participating in the global HE network society seem unlikely. HE can be used as a tool in addressing national development needs. With the necessary support and recognition from governments, HE should play a vital role in the process of reform and the revitalisation of developing countries. Africa is the least developed in terms of HE institutions. Approximately 300 institutions fit the definition of a university across the continent. While some countries on the continent, especially in Southern and Northern Africa, can claim comprehensive academic systems, most have just a few academic institutions and some countries have not yet even established differentiated post-secondary systems. It is generally assumed that most countries south of the Sahara lack adequate HE systems, or that they have no HE systems at all. Very little information on African HE systems and institutions, and how they function, is available, and there is a need for a deeper investigation into African HE systems and institutions. The vastness and diversity of the African continent does not allow for a single study of all African countries and their HE systems and institutions. It is for this reason that East Africa, comprising Kenya, Uganda and Tanzania, was chosen for this study. This specific region exhibits common characteristics amongst its countries. A British colonial history, similar secondary schooling systems and a predominance of the English language, set East Africa apart from the rest of the African continent. East African HE functions on a regional, national, and institutional level, and their way of functioning is interdependent.
- Full Text:
- Date Issued: 2008
Practical and scalable synthesis of N-Alkyl-N,N'Diacylhydrazines
- Authors: Gouws, Melissa Claire
- Date: 2008
- Subjects: Chemistry, Organic , Acylation , Insecticides
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10406 , http://hdl.handle.net/10948/696 , Chemistry, Organic , Acylation , Insecticides
- Description: The work presented in this thesis is concerned with the evaluation of potential synthetic routes for the diacylhydrazine group of compounds, and particularly, unsymmetrical diacylhydrazines. Diacylhydrazines form the basis for a relatively new group of insecticides that have molt accelerating properties, and which are considered to offer substantial advantages over other insecticides used for the control of certain insects. The overall objective for this study is to evaluate different potential synthetic routes for a model diacylhydrazine with the view to define potentially scaleable routes. The compound selected for this study was the unsymmetrical diacylhydrazine, N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)-carboxamide since it offers the same range of challenges that would be expected for the synthesis of other similar unsymmetrical diacylhydrazines. Thus, the synthesis of unsymmetrical diacylhydrazines require two reaction steps: The first step is the synthesis of the intermediate mono-acylhydrazine, while the second step is the synthesis of the desired diacylhydrazine from the intermediate mono-acylhydrazine. The most important factor in the two-step reaction sequence is to obtain a high degree of selectivity for the desired mono-acylhydrazine isomer. Acylation of t-butylhydrazine using 4-methylbenzoyl chloride can produce the desired product N-[(tert-butyl)amino](4-methylphenyl)carboxamide in yields above 90 percent, but this reaction produces a variety of by-products, including the “wrong” isomer (N-amino-N- (tert-butyl)(4-methylphenyl)carboximide). Unexpected byproducts for this particular acylation reaction, not previously reported in the literature have also been identified during this investigation. This includes a de-butylated diacylhydrazine, (4-methylphenyl)- N-[(4-methylphenyl)carbonylamino] carboxamide. Although the reaction between tert-butylhydrazine and 4-methylbenzaldehyde is very selective giving near quantitative yields of the desired hydrazone, the subsequent conversion of the hydrazone into the desired mono-acylhydrazine is problematic. The most promising route appears via bromination to form the hydrazidic bromide, followed by hydrolysis of the hydrazidic bromide. Yields for the bromination reaction during this investigation were somewhat higher than that reported previously in literature. Hydrolysis of the hydrazidic bromide, apparently also results in the hydrolysis of the reaction product to give an ester of the free acid (when an ester solvent is used). The synthesis of N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide was only briefly considered to evaluate essentially two approaches, namely: · The conversion of the monoacylhydrazine, N-[(tert-butyl)amino](4- methylphenyl)carboxamide, by acylating with either benzoyl chloride or methylbenzoate (gave 86 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide when benzoyl chloride was used as acylating agent); and · The one-pot conversion of the hydrazone, [(1E)-2-(4-methylphenyl)-1- azavinyl](tert-butyl)]amine, by bromination/hydrolysis and acylation. In this case, benzoyl chloride (2 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide), benzoic acid (80.67 percent N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)carboxamide) were evaluated as potential acylating agents.
- Full Text:
- Date Issued: 2008
- Authors: Gouws, Melissa Claire
- Date: 2008
- Subjects: Chemistry, Organic , Acylation , Insecticides
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10406 , http://hdl.handle.net/10948/696 , Chemistry, Organic , Acylation , Insecticides
- Description: The work presented in this thesis is concerned with the evaluation of potential synthetic routes for the diacylhydrazine group of compounds, and particularly, unsymmetrical diacylhydrazines. Diacylhydrazines form the basis for a relatively new group of insecticides that have molt accelerating properties, and which are considered to offer substantial advantages over other insecticides used for the control of certain insects. The overall objective for this study is to evaluate different potential synthetic routes for a model diacylhydrazine with the view to define potentially scaleable routes. The compound selected for this study was the unsymmetrical diacylhydrazine, N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)-carboxamide since it offers the same range of challenges that would be expected for the synthesis of other similar unsymmetrical diacylhydrazines. Thus, the synthesis of unsymmetrical diacylhydrazines require two reaction steps: The first step is the synthesis of the intermediate mono-acylhydrazine, while the second step is the synthesis of the desired diacylhydrazine from the intermediate mono-acylhydrazine. The most important factor in the two-step reaction sequence is to obtain a high degree of selectivity for the desired mono-acylhydrazine isomer. Acylation of t-butylhydrazine using 4-methylbenzoyl chloride can produce the desired product N-[(tert-butyl)amino](4-methylphenyl)carboxamide in yields above 90 percent, but this reaction produces a variety of by-products, including the “wrong” isomer (N-amino-N- (tert-butyl)(4-methylphenyl)carboximide). Unexpected byproducts for this particular acylation reaction, not previously reported in the literature have also been identified during this investigation. This includes a de-butylated diacylhydrazine, (4-methylphenyl)- N-[(4-methylphenyl)carbonylamino] carboxamide. Although the reaction between tert-butylhydrazine and 4-methylbenzaldehyde is very selective giving near quantitative yields of the desired hydrazone, the subsequent conversion of the hydrazone into the desired mono-acylhydrazine is problematic. The most promising route appears via bromination to form the hydrazidic bromide, followed by hydrolysis of the hydrazidic bromide. Yields for the bromination reaction during this investigation were somewhat higher than that reported previously in literature. Hydrolysis of the hydrazidic bromide, apparently also results in the hydrolysis of the reaction product to give an ester of the free acid (when an ester solvent is used). The synthesis of N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide was only briefly considered to evaluate essentially two approaches, namely: · The conversion of the monoacylhydrazine, N-[(tert-butyl)amino](4- methylphenyl)carboxamide, by acylating with either benzoyl chloride or methylbenzoate (gave 86 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide when benzoyl chloride was used as acylating agent); and · The one-pot conversion of the hydrazone, [(1E)-2-(4-methylphenyl)-1- azavinyl](tert-butyl)]amine, by bromination/hydrolysis and acylation. In this case, benzoyl chloride (2 percent N-[N-(tert-butyl)phenylcarbonylamino](4-methyl phenyl)carboxamide), benzoic acid (80.67 percent N-[N-(tertbutyl) phenylcarbonylamino](4-methylphenyl)carboxamide) were evaluated as potential acylating agents.
- Full Text:
- Date Issued: 2008
Isolation, purification and characterization of a 'factor' from Fusarium oxysporum responsible for platinum nanoparticle formation
- Authors: Govender, Yageshni
- Date: 2008
- Subjects: Nanoparticles , Platinum , Fusarium oxysporum , Fungi , Hydragenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3923 , http://hdl.handle.net/10962/d1003982 , Nanoparticles , Platinum , Fusarium oxysporum , Fungi , Hydragenase
- Description: Nanoparticles are microscopic particles in the nanometre range of between 1-100 nm. A wide variety of metal nanoparticles have been found to be produced by prokaryotic and eukaryotic organisms including several fungal species, when exposed to solutions containing metal salts. Previous studies have suggested that this bioreduction of metal particles may occur via an active reductase/hydrogenase enzyme process where H2 is the electron donor and positively charged platinum species act as the electron acceptors becoming reduced to a neutral metal nanoparticle. In view of this on going research, the current study investigated the “factors” in the fungus Fusarium oxysporum which were responsible for platinum nanoparticle formation. The fungus F.oxysporum was used in this study as it has been previously shown to produce a variety of nanoparticles including gold and silver. During exposure of the biomass to H2PtCl6 the initial response to the platinum salts was metal internalisation and subsequent reduction of H2PtCI6 to produce platinum nanoparticles. The observed localization and distribution of platinum precipitates provided some evidence for a hydrogenase mediated bioreduction of platinum salts to produce nanoparticles. Factors secreted by the fungus into the extracellular fluids, were shown to be responsible for platinum nanoparticle formation. From the identification, purification and characterisation studies it was concluded that a hydrogenase and other “factors” were responsible for platinum nanoparticle formation in F.oxysporum. Purification of the hydrogenase by freeze-drying and Sephacryl S200 size exclusion- ion exchange chromatography revealed the enzyme to be a dimer with a 29.4 and 44.5 kDa when analysed by a 10 % SDS-PAGE. Characterisation of the enzyme revealed optimal activity at a pH of 7.5 and temperature of 38 °C while it exhibited a poor thermal stability with a half life of 36 minutes. The kinetic parameters Vmax and Km were 3.16 U ml-1 and 3.64 mM respectively. The purified hydrogenase was used in subsequent experiments for the reduction of platinum salts, H2PtCl6 and PtCl2. the results indicated an over 90 % reduction of the platinum salts and TEM micrographs indicated the production of platinum nanoparticles under the various experimental conditions.
- Full Text:
- Date Issued: 2008
- Authors: Govender, Yageshni
- Date: 2008
- Subjects: Nanoparticles , Platinum , Fusarium oxysporum , Fungi , Hydragenase
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3923 , http://hdl.handle.net/10962/d1003982 , Nanoparticles , Platinum , Fusarium oxysporum , Fungi , Hydragenase
- Description: Nanoparticles are microscopic particles in the nanometre range of between 1-100 nm. A wide variety of metal nanoparticles have been found to be produced by prokaryotic and eukaryotic organisms including several fungal species, when exposed to solutions containing metal salts. Previous studies have suggested that this bioreduction of metal particles may occur via an active reductase/hydrogenase enzyme process where H2 is the electron donor and positively charged platinum species act as the electron acceptors becoming reduced to a neutral metal nanoparticle. In view of this on going research, the current study investigated the “factors” in the fungus Fusarium oxysporum which were responsible for platinum nanoparticle formation. The fungus F.oxysporum was used in this study as it has been previously shown to produce a variety of nanoparticles including gold and silver. During exposure of the biomass to H2PtCl6 the initial response to the platinum salts was metal internalisation and subsequent reduction of H2PtCI6 to produce platinum nanoparticles. The observed localization and distribution of platinum precipitates provided some evidence for a hydrogenase mediated bioreduction of platinum salts to produce nanoparticles. Factors secreted by the fungus into the extracellular fluids, were shown to be responsible for platinum nanoparticle formation. From the identification, purification and characterisation studies it was concluded that a hydrogenase and other “factors” were responsible for platinum nanoparticle formation in F.oxysporum. Purification of the hydrogenase by freeze-drying and Sephacryl S200 size exclusion- ion exchange chromatography revealed the enzyme to be a dimer with a 29.4 and 44.5 kDa when analysed by a 10 % SDS-PAGE. Characterisation of the enzyme revealed optimal activity at a pH of 7.5 and temperature of 38 °C while it exhibited a poor thermal stability with a half life of 36 minutes. The kinetic parameters Vmax and Km were 3.16 U ml-1 and 3.64 mM respectively. The purified hydrogenase was used in subsequent experiments for the reduction of platinum salts, H2PtCl6 and PtCl2. the results indicated an over 90 % reduction of the platinum salts and TEM micrographs indicated the production of platinum nanoparticles under the various experimental conditions.
- Full Text:
- Date Issued: 2008
Retrospective stock assessment of the Emperor red snapper (Lutjanus sebae) on the Seychelles Bank between 1977 and 2006
- Grandcourt, E M, Hecht, Thomas, Booth, Anthony J, Robinson, J
- Authors: Grandcourt, E M , Hecht, Thomas , Booth, Anthony J , Robinson, J
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125887 , vital:35829 , https://doi.10.1093/icesjms/fsn064
- Description: The Emperor red snapper, Lutjanus sebae, known as “Bourzwa” in the Seychelles, is distributed throughout the Indo-West Pacific from the southern Red Sea and East Africa to New Caledonia, north to Japan and south to Australia. It occurs near coral or rocky reefs and also over adjacent sand flats and gravel patches between 5 and 180 m deep (Allen, 1985; Anderson, 1986). Juveniles are frequently commensal with sea urchins (Kuiter and Tonozuka, 2001), and are found in nearshore, turbid waters (Williams and Russ, 1992), mangrove areas (Allen, 1985), and around coastal and offshore reefs (Williams and Russ, 1992). Larger L. sebae are generally found deeper, although they are also known to move into shallower water during winter (McPherson et al., 1988; Williams and Russ, 1992). Prey items include fish, crabs, other benthic crustaceans, and cephalopods. Lutjanus sebae is a large, long-lived species, attaining a maximum size of 116 cm fork length (McPherson and Squire, 1992) and maximum age of 34 years (Newman and Dunk, 2002). Despite an absence of data on its population structure, mixing, and identity, the population on the Seychelles Bank has been considered to be a unit stock for assessment purposes because of its remote location (e.g. Lablache and Carrara, 1988; Mees, 1992).
- Full Text:
- Date Issued: 2008
- Authors: Grandcourt, E M , Hecht, Thomas , Booth, Anthony J , Robinson, J
- Date: 2008
- Language: English
- Type: text , article
- Identifier: http://hdl.handle.net/10962/125887 , vital:35829 , https://doi.10.1093/icesjms/fsn064
- Description: The Emperor red snapper, Lutjanus sebae, known as “Bourzwa” in the Seychelles, is distributed throughout the Indo-West Pacific from the southern Red Sea and East Africa to New Caledonia, north to Japan and south to Australia. It occurs near coral or rocky reefs and also over adjacent sand flats and gravel patches between 5 and 180 m deep (Allen, 1985; Anderson, 1986). Juveniles are frequently commensal with sea urchins (Kuiter and Tonozuka, 2001), and are found in nearshore, turbid waters (Williams and Russ, 1992), mangrove areas (Allen, 1985), and around coastal and offshore reefs (Williams and Russ, 1992). Larger L. sebae are generally found deeper, although they are also known to move into shallower water during winter (McPherson et al., 1988; Williams and Russ, 1992). Prey items include fish, crabs, other benthic crustaceans, and cephalopods. Lutjanus sebae is a large, long-lived species, attaining a maximum size of 116 cm fork length (McPherson and Squire, 1992) and maximum age of 34 years (Newman and Dunk, 2002). Despite an absence of data on its population structure, mixing, and identity, the population on the Seychelles Bank has been considered to be a unit stock for assessment purposes because of its remote location (e.g. Lablache and Carrara, 1988; Mees, 1992).
- Full Text:
- Date Issued: 2008