The isolation and characterisation of thermostable hydantoinases from hydantoinase-producing bacteria
- Authors: Phehane, Vuyisile Ntosi
- Date: 1999
- Subjects: Hydantoin , Bacteria -- Physiology , Enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3998 , http://hdl.handle.net/10962/d1004058 , Hydantoin , Bacteria -- Physiology , Enzymes
- Description: In order to characterise thermostable hydantoin-hydrolysing enzymes from bacteria, locally-isolated thermophilic organisms were screened for the ability to convert hydantoin to N-carbamylglycine at 55°C using the hydantoinase enzyme. Cell disruption of a selected strain, RU-20-15, was conducted by French pressing to release enzyme from within the cell. In all of the experiments conducted, the amounts of product were low. In view of the low yields of products formed by the thermophiles, a previously-isolated Gram negative strain, RU-KM3L was selected from a number of mesophiles by screening for hydantoinase and carbamylase activity over a 40-55°C temperature range. Hydantoin conversion at 40°C using crude extract from pressed cells of this organism was similar to conversion at 50°C, and therefore subsequent assays were conducted at the higher temperature. The growth kinetics of RU-KM3L cells were studied and the enzyme activities of the extracts were compared in complete and chemically-defined media. The results suggested that the optimal time to harvest cells was at early stationary phase, when using complete medium for culture of cells; the specific activity of enzyme extracts produced by culture in complete medium was higher than that obtained in chemically-defined medium. 5-methylhydantoin was shown to be the preferred substrate for both the hydantoinase and carbamylase enzymes in the crude extract of RU-KM3L. The substrate specificity of the hydantoinase and carbamylase enzymes of the crude RU-KM3L extract was observed to be altered in the presence of increasing amounts of hydantoin, 5,5-dihydrouracil (DHU) and 5-thiouracil (TU) as inducers, showing selectivity for 5-methylhydantoin over hydantoin at inducer concentrations of 0.1 to 1%. A limiting effect on the hydrolysis of 5-methylhydantoin was observed when DHU and 5,5-dimethylhydantoin (DMH) were used as inducers, while the limiting effect on hydantoin specificity was observed when DHU and TU were used as inducers. The limiting effect was observed to be dependent upon the concentration of inducer, and was not observed when hydantoin was used as an inducer. The optimal time for assay of the hydantoinase enzyme in crude extract preparations at 50°C was observed to be 3h. Alkaline conditions were shown to be optimal for both the hydantoinase and carbamylase enzymes of RU-KM3L. Assay for enzyme activities of RU-KM3L extract in the presence of metal ions showed Mn²⁺ ions (and to a lesser extent, Co²⁺) to activate both the hydantoinase and carbamylase activities. Cu²⁺ ions were observed to inhibit the hydantoinase enzyme. In order to determine the location of the enzymes within the cell, cell debris from disrupted cells of RU-KM3L was removed by centrifugation. A decrease in enzyme activity in the supernatant was observed, and suggested association of the enzymes with the cell membrane. Ammonium sulfate fractionation experiments conducted on the crude extract provided further evidence for this result. Sonication of the crude enzyme extract was the only successful method for the releasing of membrane-associated enzyme. Of a number of strategies investigated, the use of sucrose at 50% (w/v) concentration was shown to preserve the hydantoinase and carbamylase enzyme activities during lyophilisation. Furthermore, assay for these enzyme activities showed the activities to be higher after lyophilisation in the presence of sucrose. However, sucrose did not increase the thermostability of lyophilised crude enzyme extracts. Water-miscible organic solvents at 1% concentration were shown to be inhibitory to the hydantoinase and carbamylase enzymes of RU-KM3L, and the inhibition was also observed to increase with increasing concentrations of these solvents. Hydantoinase activity in the presence of water-immiscible organic solvents was shown to increase with an increase in the hydrophobicity of these solvents, but the activity observed was not significantly higher than activity in the absence of solvent when hydantoin and 5-methylhydantoin were used as substrates. The possibility of reversing the hydantoinase enzyme reaction by water-immiscible organic solvents was investigated, and the results obtained suggested that the reaction could be reversed. It was thought that the partitioning of substrates or products into hydrophobic organic solvents could influence the reaction equilibrium, but the partitioning observed was not sufficient to affect reaction rates. Peptide synthesis was shown to have occurred in small amounts when the hydantoinase reaction was carried out in the presence of water-immiscible organic solvents. In conclusion, the hydantoin-hydrolyzing enzyme activity of a crude extract preparation from the bacterial strain RU-KM3L was characterised at elevated temperatures, and in the presence of watermiscible and -immiscible organic solvents.
- Full Text:
- Date Issued: 1999
- Authors: Phehane, Vuyisile Ntosi
- Date: 1999
- Subjects: Hydantoin , Bacteria -- Physiology , Enzymes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3998 , http://hdl.handle.net/10962/d1004058 , Hydantoin , Bacteria -- Physiology , Enzymes
- Description: In order to characterise thermostable hydantoin-hydrolysing enzymes from bacteria, locally-isolated thermophilic organisms were screened for the ability to convert hydantoin to N-carbamylglycine at 55°C using the hydantoinase enzyme. Cell disruption of a selected strain, RU-20-15, was conducted by French pressing to release enzyme from within the cell. In all of the experiments conducted, the amounts of product were low. In view of the low yields of products formed by the thermophiles, a previously-isolated Gram negative strain, RU-KM3L was selected from a number of mesophiles by screening for hydantoinase and carbamylase activity over a 40-55°C temperature range. Hydantoin conversion at 40°C using crude extract from pressed cells of this organism was similar to conversion at 50°C, and therefore subsequent assays were conducted at the higher temperature. The growth kinetics of RU-KM3L cells were studied and the enzyme activities of the extracts were compared in complete and chemically-defined media. The results suggested that the optimal time to harvest cells was at early stationary phase, when using complete medium for culture of cells; the specific activity of enzyme extracts produced by culture in complete medium was higher than that obtained in chemically-defined medium. 5-methylhydantoin was shown to be the preferred substrate for both the hydantoinase and carbamylase enzymes in the crude extract of RU-KM3L. The substrate specificity of the hydantoinase and carbamylase enzymes of the crude RU-KM3L extract was observed to be altered in the presence of increasing amounts of hydantoin, 5,5-dihydrouracil (DHU) and 5-thiouracil (TU) as inducers, showing selectivity for 5-methylhydantoin over hydantoin at inducer concentrations of 0.1 to 1%. A limiting effect on the hydrolysis of 5-methylhydantoin was observed when DHU and 5,5-dimethylhydantoin (DMH) were used as inducers, while the limiting effect on hydantoin specificity was observed when DHU and TU were used as inducers. The limiting effect was observed to be dependent upon the concentration of inducer, and was not observed when hydantoin was used as an inducer. The optimal time for assay of the hydantoinase enzyme in crude extract preparations at 50°C was observed to be 3h. Alkaline conditions were shown to be optimal for both the hydantoinase and carbamylase enzymes of RU-KM3L. Assay for enzyme activities of RU-KM3L extract in the presence of metal ions showed Mn²⁺ ions (and to a lesser extent, Co²⁺) to activate both the hydantoinase and carbamylase activities. Cu²⁺ ions were observed to inhibit the hydantoinase enzyme. In order to determine the location of the enzymes within the cell, cell debris from disrupted cells of RU-KM3L was removed by centrifugation. A decrease in enzyme activity in the supernatant was observed, and suggested association of the enzymes with the cell membrane. Ammonium sulfate fractionation experiments conducted on the crude extract provided further evidence for this result. Sonication of the crude enzyme extract was the only successful method for the releasing of membrane-associated enzyme. Of a number of strategies investigated, the use of sucrose at 50% (w/v) concentration was shown to preserve the hydantoinase and carbamylase enzyme activities during lyophilisation. Furthermore, assay for these enzyme activities showed the activities to be higher after lyophilisation in the presence of sucrose. However, sucrose did not increase the thermostability of lyophilised crude enzyme extracts. Water-miscible organic solvents at 1% concentration were shown to be inhibitory to the hydantoinase and carbamylase enzymes of RU-KM3L, and the inhibition was also observed to increase with increasing concentrations of these solvents. Hydantoinase activity in the presence of water-immiscible organic solvents was shown to increase with an increase in the hydrophobicity of these solvents, but the activity observed was not significantly higher than activity in the absence of solvent when hydantoin and 5-methylhydantoin were used as substrates. The possibility of reversing the hydantoinase enzyme reaction by water-immiscible organic solvents was investigated, and the results obtained suggested that the reaction could be reversed. It was thought that the partitioning of substrates or products into hydrophobic organic solvents could influence the reaction equilibrium, but the partitioning observed was not sufficient to affect reaction rates. Peptide synthesis was shown to have occurred in small amounts when the hydantoinase reaction was carried out in the presence of water-immiscible organic solvents. In conclusion, the hydantoin-hydrolyzing enzyme activity of a crude extract preparation from the bacterial strain RU-KM3L was characterised at elevated temperatures, and in the presence of watermiscible and -immiscible organic solvents.
- Full Text:
- Date Issued: 1999
The legal position of unmarried fathers in the adoption process after Fraser v Children's Court, Pretoria North, and others 1997 (2) SA 261 (CC) : towards a constitutionally-sound adoption statute
- Schäfer, Lawrence Ivan, 1972-
- Authors: Schäfer, Lawrence Ivan, 1972-
- Date: 1999
- Subjects: Unmarried fathers -- Legal status, laws, etc. -- South Africa , Unmarried fathers -- Legal status, laws, etc. -- Case studies , Children's rights -- South Africa , Adoption -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3694 , http://hdl.handle.net/10962/d1003209 , Unmarried fathers -- Legal status, laws, etc. -- South Africa , Unmarried fathers -- Legal status, laws, etc. -- Case studies , Children's rights -- South Africa , Adoption -- Law and legislation -- South Africa
- Description: The subject-matter of this thesis is the rule, previously contained in section 18(4)(d) of the Child Care Act 74 of 1983, in terms of which a mother could surrender her child born out of wedlock for adoption without the consent of its father. This section was struck down as unconstitutional by the Constitutional Court in Fraser v Children's Court, Pretoria North and others 1997 (2) SA 261 (CC), on the grounds that it violated an unmarried father’s constitutional rights to equality and non-discrimination. In the light of this judgment, this thesis seeks to articulate the constitutional parameters within which section 18(4)(d) must be amended. The requirements of Fraser are identified and discussed. Regard is also had to other constitutional rights upon which Fraser might have been decided; in particular, an unmarried father’s right to procedural fairness, and his child’s right to family or parental care. Case law from the United States, Canada, Ireland and the European Court of Human Rights is also discussed. The end product of this examination is an exposition of the various constitutional rights which vest in the father of a child born out of wedlock. A separate exposition is given of the distinct rights which vest in all children in the adoption process. The latter set of rights is drawn both from the Constitution of the Republic of South Africa Act 96 of 1996, and the United Nations Convention on the Rights of the Child. The thesis then proceeds to examine the Adoption Matters Amendment Act 56 of 1998, which was enacted in response to Fraser. The consent and notice provisions of adoption statutes in the United States, Canada, Australia, Ireland and England are also examined, and compared to the provisions of the Adoption Matters Amendment Act. The object, here, is two-fold: first, to consider the practical value of this Act; and second, to consider whether it satisfies the constitutional requirements identified earlier in this thesis. The thesis concludes with suggestions for the improvement of this Act.
- Full Text:
- Date Issued: 1999
- Authors: Schäfer, Lawrence Ivan, 1972-
- Date: 1999
- Subjects: Unmarried fathers -- Legal status, laws, etc. -- South Africa , Unmarried fathers -- Legal status, laws, etc. -- Case studies , Children's rights -- South Africa , Adoption -- Law and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:3694 , http://hdl.handle.net/10962/d1003209 , Unmarried fathers -- Legal status, laws, etc. -- South Africa , Unmarried fathers -- Legal status, laws, etc. -- Case studies , Children's rights -- South Africa , Adoption -- Law and legislation -- South Africa
- Description: The subject-matter of this thesis is the rule, previously contained in section 18(4)(d) of the Child Care Act 74 of 1983, in terms of which a mother could surrender her child born out of wedlock for adoption without the consent of its father. This section was struck down as unconstitutional by the Constitutional Court in Fraser v Children's Court, Pretoria North and others 1997 (2) SA 261 (CC), on the grounds that it violated an unmarried father’s constitutional rights to equality and non-discrimination. In the light of this judgment, this thesis seeks to articulate the constitutional parameters within which section 18(4)(d) must be amended. The requirements of Fraser are identified and discussed. Regard is also had to other constitutional rights upon which Fraser might have been decided; in particular, an unmarried father’s right to procedural fairness, and his child’s right to family or parental care. Case law from the United States, Canada, Ireland and the European Court of Human Rights is also discussed. The end product of this examination is an exposition of the various constitutional rights which vest in the father of a child born out of wedlock. A separate exposition is given of the distinct rights which vest in all children in the adoption process. The latter set of rights is drawn both from the Constitution of the Republic of South Africa Act 96 of 1996, and the United Nations Convention on the Rights of the Child. The thesis then proceeds to examine the Adoption Matters Amendment Act 56 of 1998, which was enacted in response to Fraser. The consent and notice provisions of adoption statutes in the United States, Canada, Australia, Ireland and England are also examined, and compared to the provisions of the Adoption Matters Amendment Act. The object, here, is two-fold: first, to consider the practical value of this Act; and second, to consider whether it satisfies the constitutional requirements identified earlier in this thesis. The thesis concludes with suggestions for the improvement of this Act.
- Full Text:
- Date Issued: 1999
The process of learning and teaching in supplemental instruction groups at Rhodes University
- Authors: Vorster, Jo-Anne Elizabeth
- Date: 1999
- Subjects: Group work in education , Team learning approach in education , College teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3081 , http://hdl.handle.net/10962/d1002590 , Group work in education , Team learning approach in education , College teaching -- South Africa
- Description: This thesis investigates the process of peer collaborative learning in three Supplemental Instruction (SI) groups at Rhodes University. The roles of the SI leader, the students and the task in the peer-collaborative learning-teaching process were researched. The research is rooted in sociocultural theories of learning and development. The notion of activity is thus central to this investigation. The tasks, goals and interactions in the SI sessions were analysed in order to arrive at an understanding of the process of learning-teaching in each of the three SI sessions. A method of analysis devised by Van Vlaenderen to study the process of everyday cognition in the problem solving activities of community activists (1997) was adapted for this study. The method of analysis was used to study the interaction processes of participants in the SI groups. Each interaction between the SI participants was broken into its constituent parts and labeled in terms of the goals of the interactions in relation to the preceding interaction or operation, the task or subtask under discussion, and the SI session as a whole. Data from the analysis of the activity were quantified in order to assess the quality of the learning-teaching process. A qualitative analysis of the patterns of mediation was used in conjunction with the quantified data of interaction patterns to draw conclusions about the nature of the peer collaborative learning-teaching process in the three SI sessions. The research findings indicate that the nature of the SI task is crucial; students in SI need to be able and willing to participate; and the facilitation style of the SI leader plays a role in determining the quality of the activity in the SI session. The thesis explicates learning-teaching activity that results in higher order learning.
- Full Text:
- Date Issued: 1999
- Authors: Vorster, Jo-Anne Elizabeth
- Date: 1999
- Subjects: Group work in education , Team learning approach in education , College teaching -- South Africa
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:3081 , http://hdl.handle.net/10962/d1002590 , Group work in education , Team learning approach in education , College teaching -- South Africa
- Description: This thesis investigates the process of peer collaborative learning in three Supplemental Instruction (SI) groups at Rhodes University. The roles of the SI leader, the students and the task in the peer-collaborative learning-teaching process were researched. The research is rooted in sociocultural theories of learning and development. The notion of activity is thus central to this investigation. The tasks, goals and interactions in the SI sessions were analysed in order to arrive at an understanding of the process of learning-teaching in each of the three SI sessions. A method of analysis devised by Van Vlaenderen to study the process of everyday cognition in the problem solving activities of community activists (1997) was adapted for this study. The method of analysis was used to study the interaction processes of participants in the SI groups. Each interaction between the SI participants was broken into its constituent parts and labeled in terms of the goals of the interactions in relation to the preceding interaction or operation, the task or subtask under discussion, and the SI session as a whole. Data from the analysis of the activity were quantified in order to assess the quality of the learning-teaching process. A qualitative analysis of the patterns of mediation was used in conjunction with the quantified data of interaction patterns to draw conclusions about the nature of the peer collaborative learning-teaching process in the three SI sessions. The research findings indicate that the nature of the SI task is crucial; students in SI need to be able and willing to participate; and the facilitation style of the SI leader plays a role in determining the quality of the activity in the SI session. The thesis explicates learning-teaching activity that results in higher order learning.
- Full Text:
- Date Issued: 1999
The psychological adjustment of middle managers after revolutionary organisational change
- Authors: Coates, Nicholas Robert
- Date: 1999
- Subjects: Psychology, Industrial -- South Africa Organizational change -- South Africa Organizational change -- Psychological aspects Management -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3190 , http://hdl.handle.net/10962/d1008554
- Description:
With the accelerated process of political and socio-economic transformation in South Africa, revolutionary organisational change has become a given in contemporary South African business life (Human & Horwitz, 1992). For revolutionary organisational change to succeed in South Africa, middle managers who represent the 'cement' of the organisation, need to adjust at the individual level. However, the literature on organisational change remains curiously silent about individual adjustment (Ashford, 1988). The goals of the research were firstly, to recount the middle manager's perceptions and experiences of revolutionary organisational change. Secondly, to detail the psychological re-
- Full Text:
- Date Issued: 1999
- Authors: Coates, Nicholas Robert
- Date: 1999
- Subjects: Psychology, Industrial -- South Africa Organizational change -- South Africa Organizational change -- Psychological aspects Management -- Psychological aspects
- Language: English
- Type: Thesis , Masters , MSocSc
- Identifier: vital:3190 , http://hdl.handle.net/10962/d1008554
- Description:
With the accelerated process of political and socio-economic transformation in South Africa, revolutionary organisational change has become a given in contemporary South African business life (Human & Horwitz, 1992). For revolutionary organisational change to succeed in South Africa, middle managers who represent the 'cement' of the organisation, need to adjust at the individual level. However, the literature on organisational change remains curiously silent about individual adjustment (Ashford, 1988). The goals of the research were firstly, to recount the middle manager's perceptions and experiences of revolutionary organisational change. Secondly, to detail the psychological re-
- Full Text:
- Date Issued: 1999
The relative influence of value priorities ethnicity and worries in the determination of political party affiliation amongst Ugandan university students
- Authors: Kibanja, Grace M
- Date: 1999
- Subjects: Political psychology , Uganda -- Politics and government -- 1979- , Students -- Uganda -- Political activity , College students -- Uganda -- Psychology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3003 , http://hdl.handle.net/10962/d1002512 , Political psychology , Uganda -- Politics and government -- 1979- , Students -- Uganda -- Political activity , College students -- Uganda -- Psychology
- Description: This study examines the relative influence of value priorities, ethnicity and 'worries' in the determination of political party affiliation amongst Ugandan university students. Schwartz's values questionnaire was administered to 309 male and 176 female first year students from the faculties of engineering, medicine, law, commerce, social sciences, sciences, education and mass communication at Makerere University Uganda. The sample included respondents from all of the six sub-ethnic groups in Uganda. Respondents also covered the major religious groups in the country and were also representative of the major political parties. Results from the statistical analysis on the data show that ethnicity and certain values playa role in the determination of these students' affiliation to a political party. Chi-square results show that achievement, benevolence, universalism, security, tradition and conformity values are given differing importance across political parties. And, Anova results show that the tradition value has a significant mean difference across parties. Other factors such as religion and course of study are also found to have significant influence on these student's affiliation to political parties. Although 'worries' are found not to have a significant influence on student's political party affiliation, findings show that students from different political parties differ in their ratings of the different types of ' worries'. Therefore results show that ethnicity and value priorities do infl4ence these students' affiliation to a political party but ' worries' do not. The discussion section explores these findings in the context of contemporary Ugandan politics.
- Full Text:
- Date Issued: 1999
- Authors: Kibanja, Grace M
- Date: 1999
- Subjects: Political psychology , Uganda -- Politics and government -- 1979- , Students -- Uganda -- Political activity , College students -- Uganda -- Psychology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3003 , http://hdl.handle.net/10962/d1002512 , Political psychology , Uganda -- Politics and government -- 1979- , Students -- Uganda -- Political activity , College students -- Uganda -- Psychology
- Description: This study examines the relative influence of value priorities, ethnicity and 'worries' in the determination of political party affiliation amongst Ugandan university students. Schwartz's values questionnaire was administered to 309 male and 176 female first year students from the faculties of engineering, medicine, law, commerce, social sciences, sciences, education and mass communication at Makerere University Uganda. The sample included respondents from all of the six sub-ethnic groups in Uganda. Respondents also covered the major religious groups in the country and were also representative of the major political parties. Results from the statistical analysis on the data show that ethnicity and certain values playa role in the determination of these students' affiliation to a political party. Chi-square results show that achievement, benevolence, universalism, security, tradition and conformity values are given differing importance across political parties. And, Anova results show that the tradition value has a significant mean difference across parties. Other factors such as religion and course of study are also found to have significant influence on these student's affiliation to political parties. Although 'worries' are found not to have a significant influence on student's political party affiliation, findings show that students from different political parties differ in their ratings of the different types of ' worries'. Therefore results show that ethnicity and value priorities do infl4ence these students' affiliation to a political party but ' worries' do not. The discussion section explores these findings in the context of contemporary Ugandan politics.
- Full Text:
- Date Issued: 1999
The removal of toxic heavy metals from aqueous solutions by algal extracellular polysaccharides
- Authors: Selepe, Mamaropeng Marcus
- Date: 1999
- Subjects: Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3994 , http://hdl.handle.net/10962/d1004054 , Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Description: This study investigated the possible use of algal extracellular polysaccharide as a biosorbent for removal of heavy metals (copper and lead) from aqueous solutions as a means of bioremediation for metal containing effluents. This biopolymer has good biosorbent properties and a potential to provide a cost effective, selective and efficient purification system. A variety of environmental conditions induce the production of extracellular polysaccharides in algae. The production of exopolysaccharides by Dunaliella cultures was induced by nitrogen deficient conditions. A high ratio of carbon to nitrogen source considerably enhanced the polysaccharide release. Purified extracellular polysaccharide samples exhibited a monosaccharide composition consisting of the following sugars: xylose, arabinose, 2-0-methyl mannose, mannose, glucose and galactose. The relative abundance (%) of these sugars were calculated relative to xylose. The major sugar constituent was 2-0-methyl mannose, which was present at approximately 160% relative to xylose. The percentage relative abundance of other sugars was as follows: 18.8; 86.8; 85.3 and 22.3% for arabinose; mannose; glucose and galactose respectively. The identity of the various constituents were confirmed by mass spectrometry. The ability of Dunaliella exopolysaccharides to accumulate metals was investigated. The following parameters were studied because they affect metal uptake: solution pH, biomass concentration, temperature, time and metal concentration. The uptake of both copper and lead were pH dependent. However, metal uptake was not significantly affected by temperature. Kinetic studies showed that Dunaliella extracellular polysaccharides exhibit good bioremediation properties. Metal uptake was rapid. In addition, the exopolysaccharide has good metal binding capacity with an uptake capacity for lead of 80 mg/g from a solution containing initial lead concentration of approximately 40 mg/l. Competition studies revealed that the presence of a second metal in solution inhibits uptake of the other metal compared to uptake in single metal solution of that particular metal. The presence of lead inhibited the uptake of copper from approximately 65% in single metal solution to 10% in binary metal solution. The presence of copper also inhibited lead uptake, though not to the same extent. Higher concentrations of lead could not completely prevent removal of copper from solution and visa versa. The same was true for lead which could not be displaced by a four-fold concentration of copper. Instead, a certain percentage of copper was always removed showing that lead did not compete with copper for these binding sites. In conclusion it appears that, copper and lead bind to different sites on Dunaliella exopolysaccharides and that they exhibit selective or preferential removal of lead.
- Full Text:
- Date Issued: 1999
- Authors: Selepe, Mamaropeng Marcus
- Date: 1999
- Subjects: Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3994 , http://hdl.handle.net/10962/d1004054 , Heavy metals -- Absorption and adsorption , Copper , Lead , Algae -- Biotechnology , Polysaccharides -- Biotechnology
- Description: This study investigated the possible use of algal extracellular polysaccharide as a biosorbent for removal of heavy metals (copper and lead) from aqueous solutions as a means of bioremediation for metal containing effluents. This biopolymer has good biosorbent properties and a potential to provide a cost effective, selective and efficient purification system. A variety of environmental conditions induce the production of extracellular polysaccharides in algae. The production of exopolysaccharides by Dunaliella cultures was induced by nitrogen deficient conditions. A high ratio of carbon to nitrogen source considerably enhanced the polysaccharide release. Purified extracellular polysaccharide samples exhibited a monosaccharide composition consisting of the following sugars: xylose, arabinose, 2-0-methyl mannose, mannose, glucose and galactose. The relative abundance (%) of these sugars were calculated relative to xylose. The major sugar constituent was 2-0-methyl mannose, which was present at approximately 160% relative to xylose. The percentage relative abundance of other sugars was as follows: 18.8; 86.8; 85.3 and 22.3% for arabinose; mannose; glucose and galactose respectively. The identity of the various constituents were confirmed by mass spectrometry. The ability of Dunaliella exopolysaccharides to accumulate metals was investigated. The following parameters were studied because they affect metal uptake: solution pH, biomass concentration, temperature, time and metal concentration. The uptake of both copper and lead were pH dependent. However, metal uptake was not significantly affected by temperature. Kinetic studies showed that Dunaliella extracellular polysaccharides exhibit good bioremediation properties. Metal uptake was rapid. In addition, the exopolysaccharide has good metal binding capacity with an uptake capacity for lead of 80 mg/g from a solution containing initial lead concentration of approximately 40 mg/l. Competition studies revealed that the presence of a second metal in solution inhibits uptake of the other metal compared to uptake in single metal solution of that particular metal. The presence of lead inhibited the uptake of copper from approximately 65% in single metal solution to 10% in binary metal solution. The presence of copper also inhibited lead uptake, though not to the same extent. Higher concentrations of lead could not completely prevent removal of copper from solution and visa versa. The same was true for lead which could not be displaced by a four-fold concentration of copper. Instead, a certain percentage of copper was always removed showing that lead did not compete with copper for these binding sites. In conclusion it appears that, copper and lead bind to different sites on Dunaliella exopolysaccharides and that they exhibit selective or preferential removal of lead.
- Full Text:
- Date Issued: 1999
The role of indigenous knowledge in/for environmental education: the case of a Nguni story in the Schools Water Action Project
- Authors: Masuku, Lynette Sibongile
- Date: 1999
- Subjects: Environmental education Environmental education -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1749 , http://hdl.handle.net/10962/d1003633
- Description: In March 1997 an indigenous knowledge story was included by the Schools Water Action Project (SWAP)partners in a resource pack for Water Week educational activities. This research developed as the result of an interaction between myself and some of the schools while we investigated water quality within Howick in the KwaZulu Natal Midlands. An interest in understanding the role of indigenous knowledge in/for environmental education developed. Some of the teachers and students involved in the water audit were requested to share their views on the role of indigenous knowledge in/for environmental education. From here the study broadened to also include interviews with elderly community members and environmental educators involved in materials development processes. This post-positivistic case study documents the views of a small sample of interviewees using the SWAP story entitled Sweet Water as a spring board towards a better understanding of indigenous knowledge within the school context, with a particular aim to inform educational materials development processes. The study displayed that a link which exists between indigenous knowledge and environmental education needs to be brought to the fore. This is likely to happen with the blurring of boundaries between home and school as learning contexts, a process which student interviewees emphasised, along with the need for respecting values that award respect to the environment. Elderly community members were of the view that they have a role to play in addressing educational problems such as interpersonal and intercultural respect. However, the study also raised several issues around the complexities surrounding indigenous knowledge processes, including its appropriation, commodification and reification.
- Full Text:
- Date Issued: 1999
- Authors: Masuku, Lynette Sibongile
- Date: 1999
- Subjects: Environmental education Environmental education -- South Africa -- KwaZulu-Natal
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1749 , http://hdl.handle.net/10962/d1003633
- Description: In March 1997 an indigenous knowledge story was included by the Schools Water Action Project (SWAP)partners in a resource pack for Water Week educational activities. This research developed as the result of an interaction between myself and some of the schools while we investigated water quality within Howick in the KwaZulu Natal Midlands. An interest in understanding the role of indigenous knowledge in/for environmental education developed. Some of the teachers and students involved in the water audit were requested to share their views on the role of indigenous knowledge in/for environmental education. From here the study broadened to also include interviews with elderly community members and environmental educators involved in materials development processes. This post-positivistic case study documents the views of a small sample of interviewees using the SWAP story entitled Sweet Water as a spring board towards a better understanding of indigenous knowledge within the school context, with a particular aim to inform educational materials development processes. The study displayed that a link which exists between indigenous knowledge and environmental education needs to be brought to the fore. This is likely to happen with the blurring of boundaries between home and school as learning contexts, a process which student interviewees emphasised, along with the need for respecting values that award respect to the environment. Elderly community members were of the view that they have a role to play in addressing educational problems such as interpersonal and intercultural respect. However, the study also raised several issues around the complexities surrounding indigenous knowledge processes, including its appropriation, commodification and reification.
- Full Text:
- Date Issued: 1999
The role of vitamin E succinate in regulation of growth and cyclooxygenase expression in B16 murine melanoma cells
- Van der Merwe, Adele Shanette
- Authors: Van der Merwe, Adele Shanette
- Date: 1999
- Subjects: Melanoma , Vitamin E
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3988 , http://hdl.handle.net/10962/d1004047 , Melanoma , Vitamin E
- Description: This study was undertaken to determine the effects and possible mechanism of action of vitamin E succinate supplementation on B16 murine melanoma cell growth in vitro. Studies revealed that supplementation of 5, 7 and 10µg/ml of this vitamin significantly inhibited growth of B16 cells. Non-malignant LLCMK cells supplemented with the same concentrations of vitamin E succinate resulted in similar inhibition of cell growth. The actual mechanism by which vitamin E succinate inhibits B16 cell growth is unclear, though there has been much speculation about its possible role as an antioxidant. Vitamin E succinate is not a physiological antioxidant and for this ester to behave as an antioxidant, cleavage of the ester bond must occur, releasing the antioxidant vitamin E part of the molecule. To determine whether the observed inhibitory effects on B16 cell growth were due to the intact vitamin E succinate or the vitamin E cleavage product, cleavage studies were undertaken. Results from these studies revealed that in B16 cells vitamin E succinate cleavage did not occur suggesting that the observed inhibitory effects of vitamin E succinate on B16 cells were due to the intact compound. In contrast vitamin E succinate cleavage was shown to occur in LLCMK cells, suggesting that these cells may contain an esterase capable of liberating succinic acid and vitamin E. Further studies focussed on the possible role of vitamin E succinate in regulation of cyclooxygenase activity in B16 cells as vitamin E succinate was found to effect the activity of various enzymes involved in the arachidonic acid cascade, notably cyclooxygenase, the rate-limiting enzyme in prostaglandin synthesis. Time course studies were used to determine when the cyclooxygenase protein was being produced, thus allowing an estimation of when the gene was being 'switched on'. These studies revealed that vitamin E succinate does not significantly effect cyclooxygenase activity in B16 cells over a period of 2 to 12 hours as compared to the OE control cultures. Further studies using RNA techniques investigated whether vitamin E succinate was having an effect on cyclooxygenase activity at a molecular level. These investigations were unsuccessful for the 6 day supplementation for a number of possible reasons, the main reason being RNA stability. Subsequent studies revealed an increase in COX mRNA after 2 hours, suggesting that the gene was 'switched on' soon after supplementation with vitamin E succinate, and further increases in COX mRNA were observed after 8 to 12 hours. The molecular studies were, however, inconclusive. Previous studies suggested that vitamin E succinate was indirectly causing growth inhibition of B16 cells via regulation of cyclooxygenase activity, however, this study does not support these findings and it would seem unlikely that regulation of cyclooxygenase expression in B16 cells by vitamin E succinate has a role to play in the mechanism by which vitamin E succinate inhibits growth in B16 cells.
- Full Text:
- Date Issued: 1999
- Authors: Van der Merwe, Adele Shanette
- Date: 1999
- Subjects: Melanoma , Vitamin E
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:3988 , http://hdl.handle.net/10962/d1004047 , Melanoma , Vitamin E
- Description: This study was undertaken to determine the effects and possible mechanism of action of vitamin E succinate supplementation on B16 murine melanoma cell growth in vitro. Studies revealed that supplementation of 5, 7 and 10µg/ml of this vitamin significantly inhibited growth of B16 cells. Non-malignant LLCMK cells supplemented with the same concentrations of vitamin E succinate resulted in similar inhibition of cell growth. The actual mechanism by which vitamin E succinate inhibits B16 cell growth is unclear, though there has been much speculation about its possible role as an antioxidant. Vitamin E succinate is not a physiological antioxidant and for this ester to behave as an antioxidant, cleavage of the ester bond must occur, releasing the antioxidant vitamin E part of the molecule. To determine whether the observed inhibitory effects on B16 cell growth were due to the intact vitamin E succinate or the vitamin E cleavage product, cleavage studies were undertaken. Results from these studies revealed that in B16 cells vitamin E succinate cleavage did not occur suggesting that the observed inhibitory effects of vitamin E succinate on B16 cells were due to the intact compound. In contrast vitamin E succinate cleavage was shown to occur in LLCMK cells, suggesting that these cells may contain an esterase capable of liberating succinic acid and vitamin E. Further studies focussed on the possible role of vitamin E succinate in regulation of cyclooxygenase activity in B16 cells as vitamin E succinate was found to effect the activity of various enzymes involved in the arachidonic acid cascade, notably cyclooxygenase, the rate-limiting enzyme in prostaglandin synthesis. Time course studies were used to determine when the cyclooxygenase protein was being produced, thus allowing an estimation of when the gene was being 'switched on'. These studies revealed that vitamin E succinate does not significantly effect cyclooxygenase activity in B16 cells over a period of 2 to 12 hours as compared to the OE control cultures. Further studies using RNA techniques investigated whether vitamin E succinate was having an effect on cyclooxygenase activity at a molecular level. These investigations were unsuccessful for the 6 day supplementation for a number of possible reasons, the main reason being RNA stability. Subsequent studies revealed an increase in COX mRNA after 2 hours, suggesting that the gene was 'switched on' soon after supplementation with vitamin E succinate, and further increases in COX mRNA were observed after 8 to 12 hours. The molecular studies were, however, inconclusive. Previous studies suggested that vitamin E succinate was indirectly causing growth inhibition of B16 cells via regulation of cyclooxygenase activity, however, this study does not support these findings and it would seem unlikely that regulation of cyclooxygenase expression in B16 cells by vitamin E succinate has a role to play in the mechanism by which vitamin E succinate inhibits growth in B16 cells.
- Full Text:
- Date Issued: 1999
The social construction of 'capacity building': a grounded theory study of organisation development consultants' accounts
- Authors: Eagar, Ryan
- Date: 1999
- Subjects: Organizational change -- South Africa , Business consultants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:2969 , http://hdl.handle.net/10962/d1002478 , Organizational change -- South Africa , Business consultants -- South Africa
- Description: The primary aim of this thesis is to explore, through organisation development (OD) consultants' accounts, the meaning of 'capacity building' in the South African development context. The need for theory development in this area is apparent from two interrelated vantage points. Firstly, while 'capacity building' is an increasingly espoused development approach, it is seen to be a confusing and ill-defined concept, for which there exists no adequate theory. Secondly, there is an growing call within the OD field to perfonn 'recOIlllaissance' (Weick,1990) on OD as it is being practised in different socio-historical and organisational contexts, so as to discern future trends for this discipline. Due to the lack of documented debate which grounds OD issues in the South African development sector, OD practitioners' 'capacity building' interventions were seen to provide suitably unchartered terrain for this study. Given that theory generation was intended, the general epistemological principles provided by Glaser and Strauss's (1967) 'grounded theory' methodology were adopted. As a way of avoiding some of the criticisms and limitations of this approach, this thesis followed later conceptualisations of this method, in particular its reframing within the social constructionist idiom. In accordance with this perspective, this study directed attention to the ways in which OD consultants, in a non-governmental organisational (NGO) sector known as 'intermediary' NGOs, accounted for their 'capacity building' role in this development context. The results, based on in-depth interviews with ten OD consultants, indicate that 'capacity building' is an elusive and inchoate concept with more than one meaning for the participants. Their narrative account variously constructs 'capacity building' as value-driven OD process facilitation; funder and market regulated service provision; and people-driven product delivery. As a result of this multi-vocal construction, the participants' accounts reveal that OD consultancy in this sector is primarily concerned with 'managing the tensions' of the consultants' ambiguous and contradictory roles. By examining how the tensions articulated by the consultants inhere in their relationship to the environment in which they operate, this thesis firstly explores how the contradiction and anlbiguity attached to this concept can be traced to different stakeholder expectations of 'capacity building'. Secondly, it exanlines how these different stakeholder discourses conflict with each other and with an OD perspective. Thirdly, through an explication of the core category of 'managing tensions', it explores the image of OD consulting as a 'shifting and inconstant balancing act'. Fourthly, it shows how there exist wider contextual forces operating in the development sector which serve to throw these consultants 'off balance' and into delimited and 'received' service provision roles which run counter to their raison d'etre. Finally, the research examines new ways of approaching the 'capacity building' question and of understanding the nature of OD consultancy. It concludes with an attempt to respond to a conceptual aporia in OD literature by examining possible alternative images and metaphors for the role of the OD consultant.
- Full Text:
- Date Issued: 1999
- Authors: Eagar, Ryan
- Date: 1999
- Subjects: Organizational change -- South Africa , Business consultants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:2969 , http://hdl.handle.net/10962/d1002478 , Organizational change -- South Africa , Business consultants -- South Africa
- Description: The primary aim of this thesis is to explore, through organisation development (OD) consultants' accounts, the meaning of 'capacity building' in the South African development context. The need for theory development in this area is apparent from two interrelated vantage points. Firstly, while 'capacity building' is an increasingly espoused development approach, it is seen to be a confusing and ill-defined concept, for which there exists no adequate theory. Secondly, there is an growing call within the OD field to perfonn 'recOIlllaissance' (Weick,1990) on OD as it is being practised in different socio-historical and organisational contexts, so as to discern future trends for this discipline. Due to the lack of documented debate which grounds OD issues in the South African development sector, OD practitioners' 'capacity building' interventions were seen to provide suitably unchartered terrain for this study. Given that theory generation was intended, the general epistemological principles provided by Glaser and Strauss's (1967) 'grounded theory' methodology were adopted. As a way of avoiding some of the criticisms and limitations of this approach, this thesis followed later conceptualisations of this method, in particular its reframing within the social constructionist idiom. In accordance with this perspective, this study directed attention to the ways in which OD consultants, in a non-governmental organisational (NGO) sector known as 'intermediary' NGOs, accounted for their 'capacity building' role in this development context. The results, based on in-depth interviews with ten OD consultants, indicate that 'capacity building' is an elusive and inchoate concept with more than one meaning for the participants. Their narrative account variously constructs 'capacity building' as value-driven OD process facilitation; funder and market regulated service provision; and people-driven product delivery. As a result of this multi-vocal construction, the participants' accounts reveal that OD consultancy in this sector is primarily concerned with 'managing the tensions' of the consultants' ambiguous and contradictory roles. By examining how the tensions articulated by the consultants inhere in their relationship to the environment in which they operate, this thesis firstly explores how the contradiction and anlbiguity attached to this concept can be traced to different stakeholder expectations of 'capacity building'. Secondly, it exanlines how these different stakeholder discourses conflict with each other and with an OD perspective. Thirdly, through an explication of the core category of 'managing tensions', it explores the image of OD consulting as a 'shifting and inconstant balancing act'. Fourthly, it shows how there exist wider contextual forces operating in the development sector which serve to throw these consultants 'off balance' and into delimited and 'received' service provision roles which run counter to their raison d'etre. Finally, the research examines new ways of approaching the 'capacity building' question and of understanding the nature of OD consultancy. It concludes with an attempt to respond to a conceptual aporia in OD literature by examining possible alternative images and metaphors for the role of the OD consultant.
- Full Text:
- Date Issued: 1999
The use of investigative methods in teaching and learning primary mathematics in Lebowa schools : a case study
- Authors: Sebela, Mokgoko Petrus
- Date: 1999
- Subjects: Mathematics -- Study and teaching (Primary) -- South Africa -- Northern Province -- Case studies Mathematics -- Study and teaching (Primary) -- South Africa -- Northern Province
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1814 , http://hdl.handle.net/10962/d1003700
- Description: This is a report on research conducted in Lebowa (Northern Province) Primary Mathematics Project schools. In view of the high failure rate of matric students, the researcher believes that it is necessary that ways should be devised to improve mathematics understanding from the first level of schooling. A research study was made of constructivist and investigative teaching and learning methods as employed by teachers in a number of primary schools in the area. The researcher believes that investigative and constructivist teaching approaches produce better results than the traditional approach. He further believes that children learn better in a co-operative non-threatening classroom environment. A pilot study was made with two experimental schools and two control schools. The schools were selected from both urban and rural areas. The experimental schools are operating under the PMP and the control schools are not. The experimental schools are also supported by expert teachers called key teachers. Many of these key teachers have attended courses at Leeds University, while others have been trained locally in the theory and practice of constructivist and investigative teaching and learning. Chapter 3 illustrates clearly what is done in the Project schools. The methodology employed in the research included qUestionnaire responses from 174 teachers. Written tests by four schools (350 pupils), and interviews with 55 people, including directors of education, inspectors, principals, teachers and parents. Observations in classes were also done. Another questionnaire was given to 484 pupils. The tests were mitten on two occasions: an initial test was written during November 1993, the second year of the PMP project, while a second test was written the following year. Data collected was analysed and positive results obtained. The results from the tests indicated that pupils in experimental schools where constructivist and investigative approaches are used, perform better than those from schools where the traditional approach is still used. They indicated that children in PMP schools develop a better understanding of mathematics. This would seem to indicate that the constructivist and investigative approach to teaching produces better results than the traditional approaches. The reader will find graphs indicating the results and their analysis in Chapters 4 and 5. It is recommended by the researcher that: - Constructivist and investigative teaching and learning methods be introduced to all schools. - The services of key teachers be supported by the Department - The Department should equip all schools with the necessary materials for proper teaching and learning, or provide materials for schools to make their own teaching aids. - Teachers be involved with materials production where they are given guidance on how teaching aids can be made. - The curriculum for primary school mathematics be revised and changed, especially in view of the fact that at present it does not cater for local needs. It was planned by whites and it caters mainly for those with an European cultural background.
- Full Text:
- Date Issued: 1999
- Authors: Sebela, Mokgoko Petrus
- Date: 1999
- Subjects: Mathematics -- Study and teaching (Primary) -- South Africa -- Northern Province -- Case studies Mathematics -- Study and teaching (Primary) -- South Africa -- Northern Province
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1814 , http://hdl.handle.net/10962/d1003700
- Description: This is a report on research conducted in Lebowa (Northern Province) Primary Mathematics Project schools. In view of the high failure rate of matric students, the researcher believes that it is necessary that ways should be devised to improve mathematics understanding from the first level of schooling. A research study was made of constructivist and investigative teaching and learning methods as employed by teachers in a number of primary schools in the area. The researcher believes that investigative and constructivist teaching approaches produce better results than the traditional approach. He further believes that children learn better in a co-operative non-threatening classroom environment. A pilot study was made with two experimental schools and two control schools. The schools were selected from both urban and rural areas. The experimental schools are operating under the PMP and the control schools are not. The experimental schools are also supported by expert teachers called key teachers. Many of these key teachers have attended courses at Leeds University, while others have been trained locally in the theory and practice of constructivist and investigative teaching and learning. Chapter 3 illustrates clearly what is done in the Project schools. The methodology employed in the research included qUestionnaire responses from 174 teachers. Written tests by four schools (350 pupils), and interviews with 55 people, including directors of education, inspectors, principals, teachers and parents. Observations in classes were also done. Another questionnaire was given to 484 pupils. The tests were mitten on two occasions: an initial test was written during November 1993, the second year of the PMP project, while a second test was written the following year. Data collected was analysed and positive results obtained. The results from the tests indicated that pupils in experimental schools where constructivist and investigative approaches are used, perform better than those from schools where the traditional approach is still used. They indicated that children in PMP schools develop a better understanding of mathematics. This would seem to indicate that the constructivist and investigative approach to teaching produces better results than the traditional approaches. The reader will find graphs indicating the results and their analysis in Chapters 4 and 5. It is recommended by the researcher that: - Constructivist and investigative teaching and learning methods be introduced to all schools. - The services of key teachers be supported by the Department - The Department should equip all schools with the necessary materials for proper teaching and learning, or provide materials for schools to make their own teaching aids. - Teachers be involved with materials production where they are given guidance on how teaching aids can be made. - The curriculum for primary school mathematics be revised and changed, especially in view of the fact that at present it does not cater for local needs. It was planned by whites and it caters mainly for those with an European cultural background.
- Full Text:
- Date Issued: 1999
Through our eyes: teachers using cameras to engage in environmental education curriculum development processes
- Authors: Du Toit, Derick
- Date: 1999
- Subjects: Environmental education -- South Africa Curriculum change -- South Africa Photography in education Competency-based education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1800 , http://hdl.handle.net/10962/d1003685
- Description: This research explores the potential for engaging teachers in school-based environmental education curriculum development processes by using camera. The research, through its epistemological and ontological position, is closely linked to educational orientations associated with aspects of outcomes-based educational transformation in South Africa. A participatory approach that recognises teachers as co-researchers, each bringing to the inquiry her or his questions and constructions of meaning, was adopted. Participatory inquiry was initiated by setting up cluster meetings that allowed for teacher inputs through open dialogic processes. Fundamental to the inquiry is the notion that context shapes curriculum and curriculum development processes. It was from this orientation that a group of 13 teachers, using cameras to create visual narratives, explored their own diverse and complex contexts. These narratives (or stories) form the basis for further inquiry and development of sophistication with respect to the concept of environment. The research process is critically and reflexively documented as a series of field and research texts constructed from a variety of data sources gathered over the period of one year. The work is presented as a process of engaging critically with environmental education curriculum development and an opportunity to raise questions, rather than seek answers in this regard.
- Full Text:
- Date Issued: 1999
- Authors: Du Toit, Derick
- Date: 1999
- Subjects: Environmental education -- South Africa Curriculum change -- South Africa Photography in education Competency-based education -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1800 , http://hdl.handle.net/10962/d1003685
- Description: This research explores the potential for engaging teachers in school-based environmental education curriculum development processes by using camera. The research, through its epistemological and ontological position, is closely linked to educational orientations associated with aspects of outcomes-based educational transformation in South Africa. A participatory approach that recognises teachers as co-researchers, each bringing to the inquiry her or his questions and constructions of meaning, was adopted. Participatory inquiry was initiated by setting up cluster meetings that allowed for teacher inputs through open dialogic processes. Fundamental to the inquiry is the notion that context shapes curriculum and curriculum development processes. It was from this orientation that a group of 13 teachers, using cameras to create visual narratives, explored their own diverse and complex contexts. These narratives (or stories) form the basis for further inquiry and development of sophistication with respect to the concept of environment. The research process is critically and reflexively documented as a series of field and research texts constructed from a variety of data sources gathered over the period of one year. The work is presented as a process of engaging critically with environmental education curriculum development and an opportunity to raise questions, rather than seek answers in this regard.
- Full Text:
- Date Issued: 1999
Towards modelling the formation of ore bodies initial results dealing with the fluid mechanical aspects of magma chamber convection
- Authors: Botha, André Erasmus
- Date: 1999
- Subjects: Ore deposits , Fluid mechanics , Magmatism
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5492 , http://hdl.handle.net/10962/d1005278 , Ore deposits , Fluid mechanics , Magmatism
- Description: This thesis forms part of a larger effort which aims to establish the means of assessing the fluid mechanical behaviour of magma 1 as it cools inside a magma chamber surrounded by porous country rock. The reason for doing so is to advance the understanding of some types of mineral deposits; for example,the Platinum Group Elements (PGEs). The magma is modelled with the governing equations for a single-phase incompressible Newtonian fluid with variable viscosity and density. In this thesis, thermal conductivity and specific heat are approximated as constants and the country rock is treated as a conducting solid so as to save on computational time in the initial phases of the project. A basic review of the relevant literature is presented as background material and three basic models of magma chambers are discussed: crystal settling, compositional convection and double diffusive convection.The results presented in this thesis are from finite element calculations by a commercial computer code: ANSYS 5.4. This code has been employed in industry for over 26 years and has a long and successful benchmark history. In this context, finite element methods that are applicable to the code are discussed in chapter 5. In chapter 6, results that were obtained in the course of this research are presented. The thesis concludes with an indication of the possible geological significance of the results and various refinements that should be made to future models.
- Full Text:
- Date Issued: 1999
- Authors: Botha, André Erasmus
- Date: 1999
- Subjects: Ore deposits , Fluid mechanics , Magmatism
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5492 , http://hdl.handle.net/10962/d1005278 , Ore deposits , Fluid mechanics , Magmatism
- Description: This thesis forms part of a larger effort which aims to establish the means of assessing the fluid mechanical behaviour of magma 1 as it cools inside a magma chamber surrounded by porous country rock. The reason for doing so is to advance the understanding of some types of mineral deposits; for example,the Platinum Group Elements (PGEs). The magma is modelled with the governing equations for a single-phase incompressible Newtonian fluid with variable viscosity and density. In this thesis, thermal conductivity and specific heat are approximated as constants and the country rock is treated as a conducting solid so as to save on computational time in the initial phases of the project. A basic review of the relevant literature is presented as background material and three basic models of magma chambers are discussed: crystal settling, compositional convection and double diffusive convection.The results presented in this thesis are from finite element calculations by a commercial computer code: ANSYS 5.4. This code has been employed in industry for over 26 years and has a long and successful benchmark history. In this context, finite element methods that are applicable to the code are discussed in chapter 5. In chapter 6, results that were obtained in the course of this research are presented. The thesis concludes with an indication of the possible geological significance of the results and various refinements that should be made to future models.
- Full Text:
- Date Issued: 1999
Women's understandings and experiences of empowerment in an organisation: a qualitative feminist approach
- Authors: Jamieson, Sally Anne
- Date: 1999
- Subjects: Employee empowerment , Women -- Employment -- Social aspects , Feminism , Psychology, Industrial
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2997 , http://hdl.handle.net/10962/d1002506 , Employee empowerment , Women -- Employment -- Social aspects , Feminism , Psychology, Industrial
- Description: This study explores women's understandings and experiences of empowerment so that they could empower themselves by using their own knowledge to see through factors that serve to disempower them. At a time when empowerment and its future is under intense discussion in South Africa, it seems wise to move away from quantitative studies which do not facilitate the development of comprehensive theory in industrial psychology. This study provides a qualitative feminist analysis of women's understandings and experiences of empowerment in an organisation. Written protocols, interviews and a workshop were used as data collection tools and seven women from one organisation participated in the study. The research revealed that women understand and experience empowerment in a number of ways. These understandings and experiences are affected by various factors: organisational factors; personal characteristics and abilities; their relationship with others at work and at home; and societal factors such as double standards for men and women and role expectations. The breadth and scope of the results imply that any attempt to empower women should include relational, motivational and feminist perspectives on power and empowerment. In addition, the results indicate that providing a space in which the women could explore the network of disempowering practices in their lives, was empowering for the women. Through the process of the research, the participants' understandings of empowerment evolved from viewing empowerment as something that is predominantly external (for example, influenced by others and organisational factors) to something that is internal (for example, influenced by motivational factors). This study cautions against seeing empowerment as something that is solely internal because by doing so women are placing the responsibility of empowerment upon themselves thus setting themselves up for failure. However, through the process of seeing empowerment as internal, the women were able to move towards a feminist understanding of empowerment in which not only is empowerment external ("out there") or internal ("within") but includes acknowledging one's own responsibility in empowerment as well as external societal factors that serve to hamper women.
- Full Text:
- Date Issued: 1999
- Authors: Jamieson, Sally Anne
- Date: 1999
- Subjects: Employee empowerment , Women -- Employment -- Social aspects , Feminism , Psychology, Industrial
- Language: English
- Type: Thesis , Masters , MA
- Identifier: vital:2997 , http://hdl.handle.net/10962/d1002506 , Employee empowerment , Women -- Employment -- Social aspects , Feminism , Psychology, Industrial
- Description: This study explores women's understandings and experiences of empowerment so that they could empower themselves by using their own knowledge to see through factors that serve to disempower them. At a time when empowerment and its future is under intense discussion in South Africa, it seems wise to move away from quantitative studies which do not facilitate the development of comprehensive theory in industrial psychology. This study provides a qualitative feminist analysis of women's understandings and experiences of empowerment in an organisation. Written protocols, interviews and a workshop were used as data collection tools and seven women from one organisation participated in the study. The research revealed that women understand and experience empowerment in a number of ways. These understandings and experiences are affected by various factors: organisational factors; personal characteristics and abilities; their relationship with others at work and at home; and societal factors such as double standards for men and women and role expectations. The breadth and scope of the results imply that any attempt to empower women should include relational, motivational and feminist perspectives on power and empowerment. In addition, the results indicate that providing a space in which the women could explore the network of disempowering practices in their lives, was empowering for the women. Through the process of the research, the participants' understandings of empowerment evolved from viewing empowerment as something that is predominantly external (for example, influenced by others and organisational factors) to something that is internal (for example, influenced by motivational factors). This study cautions against seeing empowerment as something that is solely internal because by doing so women are placing the responsibility of empowerment upon themselves thus setting themselves up for failure. However, through the process of seeing empowerment as internal, the women were able to move towards a feminist understanding of empowerment in which not only is empowerment external ("out there") or internal ("within") but includes acknowledging one's own responsibility in empowerment as well as external societal factors that serve to hamper women.
- Full Text:
- Date Issued: 1999