Association between teacher confidence and student mathematics outcomes
- Authors: Qwelani, Noluthando
- Date: 2018
- Subjects: Human capital
- Language: English
- Type: Thesis , Masters , MCom (Economics)
- Identifier: http://hdl.handle.net/10353/13955 , vital:39732
- Description: Teacher attributes such as teacher’s confidence in knowledge are important in the ability to teach. It is further, expected in developing countries that teachers from high socio-economic schools are highly confident in teaching mathematics whilst teachers from low socioeconomic schools are expected to be less confident. Hence, teacher attributes decisions are of great importance in achieving skills development goals. The realisation of the impact teachers’ confidence has on mathematics performance requires an investigation based on multilateral measures of teacher confidence. The purpose of this study is to investigate and analyse the impact of teacher abilities on student’s performance on mathematics in South Africa, this will be realised through an analysis of teacher confidence as the main variable and teacher qualifications, teacher characteristics and socio economic status as controlling variables. The study employed Trends in International Mathematics and Sciences studies (TIMSS) 2011 cross sectional data for South Africa. Descriptive statistics, inferential statistics and the Ordinary Least Squares (OLS) econometric technique were employed in analysing the data. The empirical results revealed that majority of South African teachers rated themselves highly confident but showed no significant impact in the performance of students. This implies that South African teachers who produce poor student’s performance are not open about their lack of confidence in teaching mathematics. However, from the student’s perspective, teacher confidence showed a strong impact on students’ performance in mathematics. The third findings were that, teachers who are happy as educators do not have a significant impact at all. The empirical results also revealed that teachers who felt they wee being allocated more than enough time to teach mathematics showed a strong negative relationship with student performance when compared to teachers who felt otherwise. The findings from the study imply that an open policy should be encouraged in which teachers are encouraged to openly express their views and any shortcomings. This will make it easier to identify the best intervention strategy on helping the teachers. Based on the findings again, it is encouraged that periodic training of mathematical teachers be encouraged. This is likely to boost teacher’s confidence and improve the mathematical results in the country.
- Full Text:
- Date Issued: 2018
- Authors: Qwelani, Noluthando
- Date: 2018
- Subjects: Human capital
- Language: English
- Type: Thesis , Masters , MCom (Economics)
- Identifier: http://hdl.handle.net/10353/13955 , vital:39732
- Description: Teacher attributes such as teacher’s confidence in knowledge are important in the ability to teach. It is further, expected in developing countries that teachers from high socio-economic schools are highly confident in teaching mathematics whilst teachers from low socioeconomic schools are expected to be less confident. Hence, teacher attributes decisions are of great importance in achieving skills development goals. The realisation of the impact teachers’ confidence has on mathematics performance requires an investigation based on multilateral measures of teacher confidence. The purpose of this study is to investigate and analyse the impact of teacher abilities on student’s performance on mathematics in South Africa, this will be realised through an analysis of teacher confidence as the main variable and teacher qualifications, teacher characteristics and socio economic status as controlling variables. The study employed Trends in International Mathematics and Sciences studies (TIMSS) 2011 cross sectional data for South Africa. Descriptive statistics, inferential statistics and the Ordinary Least Squares (OLS) econometric technique were employed in analysing the data. The empirical results revealed that majority of South African teachers rated themselves highly confident but showed no significant impact in the performance of students. This implies that South African teachers who produce poor student’s performance are not open about their lack of confidence in teaching mathematics. However, from the student’s perspective, teacher confidence showed a strong impact on students’ performance in mathematics. The third findings were that, teachers who are happy as educators do not have a significant impact at all. The empirical results also revealed that teachers who felt they wee being allocated more than enough time to teach mathematics showed a strong negative relationship with student performance when compared to teachers who felt otherwise. The findings from the study imply that an open policy should be encouraged in which teachers are encouraged to openly express their views and any shortcomings. This will make it easier to identify the best intervention strategy on helping the teachers. Based on the findings again, it is encouraged that periodic training of mathematical teachers be encouraged. This is likely to boost teacher’s confidence and improve the mathematical results in the country.
- Full Text:
- Date Issued: 2018
Attitudes and perceptions of retail workers towards trade unions: the case of SACCAWU members in KwaZakhele Shoprite-Checkers
- Authors: Majola, Ezekiel
- Date: 2018
- Subjects: Retail trade -- Labor unions -- South Africa -- Port Elizabeth , Labor unions -- South Africa -- Port Elizabeth Retail trade -- Employees -- South Africa -- Port Elizabeth South African Commercial Catering and Allied Workers Union (SACCAWU)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/31499 , vital:31496
- Description: The South African trade union movement faces challenges, that are negatively affecting their role and relevance to their members. It is argued that the use of contract workers in the labour market has significantly reduced the bargaining power of the unions, mainly because the unions are finding it difficult to mobilize contract workers and the workers themselves are believed to be reluctant to join trade unions (Mathekga, 2009). This research project investigated and sought to provide an account of the attitudes and perceptions of the retail workers towards their retail trade union in South Africa. South African Commercial Catering and Allied Workers Union (SACCAWU) is one of the trade unions that is representing these workers in the retail sector and thus also affected by the use of flexible employment arrangements, global work insecurity, and poorly organized labour worldwide. Globally, trade unions are not exempted from the impact of the use flexible labour. Lynch, Pyman, Bailey & Price (2009) pointed out that workers in the European retail sector are employed mainly as contract workers and these workers are rarely involved in trade union activities, consequently the number of unionized workers in the workplace is declining. This context speaks to the changing of attitudes of workers towards their unions. This research study explores the attitudes and perceptions of SACCAWU members towards their union in the retail sector, South Africa. The study was conducted in Port Elizabeth, using in-depth interviews, focus group discussions and observations to ascertain the worker participation and perceptions about their union, SACCAWU. The study seems to confirm most of the labour studies scholars work on disconnection between labour unions and their members, while increasing ‘precarity’ forces workers to stay on unionized despite the negative attitude prevailing.
- Full Text:
- Date Issued: 2018
- Authors: Majola, Ezekiel
- Date: 2018
- Subjects: Retail trade -- Labor unions -- South Africa -- Port Elizabeth , Labor unions -- South Africa -- Port Elizabeth Retail trade -- Employees -- South Africa -- Port Elizabeth South African Commercial Catering and Allied Workers Union (SACCAWU)
- Language: English
- Type: Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10948/31499 , vital:31496
- Description: The South African trade union movement faces challenges, that are negatively affecting their role and relevance to their members. It is argued that the use of contract workers in the labour market has significantly reduced the bargaining power of the unions, mainly because the unions are finding it difficult to mobilize contract workers and the workers themselves are believed to be reluctant to join trade unions (Mathekga, 2009). This research project investigated and sought to provide an account of the attitudes and perceptions of the retail workers towards their retail trade union in South Africa. South African Commercial Catering and Allied Workers Union (SACCAWU) is one of the trade unions that is representing these workers in the retail sector and thus also affected by the use of flexible employment arrangements, global work insecurity, and poorly organized labour worldwide. Globally, trade unions are not exempted from the impact of the use flexible labour. Lynch, Pyman, Bailey & Price (2009) pointed out that workers in the European retail sector are employed mainly as contract workers and these workers are rarely involved in trade union activities, consequently the number of unionized workers in the workplace is declining. This context speaks to the changing of attitudes of workers towards their unions. This research study explores the attitudes and perceptions of SACCAWU members towards their union in the retail sector, South Africa. The study was conducted in Port Elizabeth, using in-depth interviews, focus group discussions and observations to ascertain the worker participation and perceptions about their union, SACCAWU. The study seems to confirm most of the labour studies scholars work on disconnection between labour unions and their members, while increasing ‘precarity’ forces workers to stay on unionized despite the negative attitude prevailing.
- Full Text:
- Date Issued: 2018
Attitudes of midwives towards the use of traditional medicine among pregnant women in Nelson Mandela Bay
- Simelane, Nompumelelo Andiswa
- Authors: Simelane, Nompumelelo Andiswa
- Date: 2018
- Subjects: Midwifery -- South Africa -- Nelson Mandela Bay Municipality , Pregnancy -- Alternative treatment -- South Africa -- Nelson Mandela Bay Municipality Women's health services -- Social aspects -- South Africa -- Nelson Mandela Bay Municipality Traditional medicine -- South Africa -- Nelson Mandela Bay Municipality Integrative medicine -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: http://hdl.handle.net/10948/23197 , vital:30452
- Description: The use of traditional medicines by pregnant women is a global concern. Despite limited theoretical evidence on the safety profile of traditional medicines to substantiate their use in pregnancy, expectant mothers are found to be widely using them. Safety concerns related to traditional medicine use in pregnancy include its use during the critical embryonic period, antenatal and intrapartum periods. These medications were associated with complications such as obstructed labour, foetal distress, emergency caesarean sections having to be performed and neonates delivered with low Apgar scorings. Midwives are usually the first and at times the only healthcare providers that come into contact with pregnant women. It was therefore necessary to investigate the midwives’ attitudes towards the use of traditional medicine among pregnant women. The objectives of this study were to: Explore and describe the attitudes of midwives towards the use of traditional medicine in Nelson Mandela Bay. Based on the findings of the study, make recommendations for midwives and nurse managers on how they could inform pregnant women of the benefits and harms of using traditional medicine during pregnancy. The study was conducted between November 2016 and January 2017, using a quantitative approach with an explorative, descriptive, and contextual design having obtained the necessary approval from the university and relevant authorities. The research population was midwives who work in maternity units in Nelson Mandela Bay. Self-administered questionnaires were used to collect data from conveniently sampled participants using set inclusion and exclusion criteria after obtaining informed consent. Data were captured by the researcher on a Microsoft Excel spread sheet and were reduced and analysed with the help of a statistician using the software package IBM SPSS Statistics 24 to ensure efficacy of the results. One hundred and twenty questionnaires were distributed and 89 were returned, yielding a 74% response rate. From the research findings, midwives in the Nelson Mandela Bay do not support the use of traditional medicine during pregnancy. Midwives acknowledged their responsibility to enquire and provide relevant information regarding the use of traditional medicine in pregnancy. Furthermore, midwives associated the use of traditional medicine with womens’ cultural diversity and lack of knowledge about pregnancy and labour. Based on these findings, recommendations for midwives and nurse managers on how they could inform pregnant women of the benefits and harms of using traditional medicine during pregnancy were made. Further recommendations were made for midwifery practice, nursing education and future research. The researcher used a literature control to ensure validation and integrity of the study. Further quality of the study was maintained by observing the principles of reliability and validity. Ethical considerations were guided by the Belmont Report adopting the principles of respect for persons, beneficence, and justice.
- Full Text:
- Date Issued: 2018
- Authors: Simelane, Nompumelelo Andiswa
- Date: 2018
- Subjects: Midwifery -- South Africa -- Nelson Mandela Bay Municipality , Pregnancy -- Alternative treatment -- South Africa -- Nelson Mandela Bay Municipality Women's health services -- Social aspects -- South Africa -- Nelson Mandela Bay Municipality Traditional medicine -- South Africa -- Nelson Mandela Bay Municipality Integrative medicine -- South Africa -- Nelson Mandela Bay Municipality
- Language: English
- Type: Thesis , Masters , MCur
- Identifier: http://hdl.handle.net/10948/23197 , vital:30452
- Description: The use of traditional medicines by pregnant women is a global concern. Despite limited theoretical evidence on the safety profile of traditional medicines to substantiate their use in pregnancy, expectant mothers are found to be widely using them. Safety concerns related to traditional medicine use in pregnancy include its use during the critical embryonic period, antenatal and intrapartum periods. These medications were associated with complications such as obstructed labour, foetal distress, emergency caesarean sections having to be performed and neonates delivered with low Apgar scorings. Midwives are usually the first and at times the only healthcare providers that come into contact with pregnant women. It was therefore necessary to investigate the midwives’ attitudes towards the use of traditional medicine among pregnant women. The objectives of this study were to: Explore and describe the attitudes of midwives towards the use of traditional medicine in Nelson Mandela Bay. Based on the findings of the study, make recommendations for midwives and nurse managers on how they could inform pregnant women of the benefits and harms of using traditional medicine during pregnancy. The study was conducted between November 2016 and January 2017, using a quantitative approach with an explorative, descriptive, and contextual design having obtained the necessary approval from the university and relevant authorities. The research population was midwives who work in maternity units in Nelson Mandela Bay. Self-administered questionnaires were used to collect data from conveniently sampled participants using set inclusion and exclusion criteria after obtaining informed consent. Data were captured by the researcher on a Microsoft Excel spread sheet and were reduced and analysed with the help of a statistician using the software package IBM SPSS Statistics 24 to ensure efficacy of the results. One hundred and twenty questionnaires were distributed and 89 were returned, yielding a 74% response rate. From the research findings, midwives in the Nelson Mandela Bay do not support the use of traditional medicine during pregnancy. Midwives acknowledged their responsibility to enquire and provide relevant information regarding the use of traditional medicine in pregnancy. Furthermore, midwives associated the use of traditional medicine with womens’ cultural diversity and lack of knowledge about pregnancy and labour. Based on these findings, recommendations for midwives and nurse managers on how they could inform pregnant women of the benefits and harms of using traditional medicine during pregnancy were made. Further recommendations were made for midwifery practice, nursing education and future research. The researcher used a literature control to ensure validation and integrity of the study. Further quality of the study was maintained by observing the principles of reliability and validity. Ethical considerations were guided by the Belmont Report adopting the principles of respect for persons, beneficence, and justice.
- Full Text:
- Date Issued: 2018
Automatic unfair dismissal with reference to section 187(1)(c) of the Labour Relations Act
- Authors: Janniker, Jonathan
- Date: 2018
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Unfair labor practices -- South Africa Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/30584 , vital:30966
- Description: Automatic unfair dismissal are relatively new concept in South African employment law. The concept was only introduced in South African legislation with the promulgation of the labour relations act 66 of 1995(hearafter LRA) The concept however, found its roots from international labour organisation convention 58 of 1982. The court in South Africa under the guidance of the ILO convention were limited to two possible ways of dealing with automatically unfair dismissals. One was to criminalize the practice, and other was to ensure that such dismissals were considered unacceptable.
- Full Text: false
- Date Issued: 2018
- Authors: Janniker, Jonathan
- Date: 2018
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Unfair labor practices -- South Africa Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/30584 , vital:30966
- Description: Automatic unfair dismissal are relatively new concept in South African employment law. The concept was only introduced in South African legislation with the promulgation of the labour relations act 66 of 1995(hearafter LRA) The concept however, found its roots from international labour organisation convention 58 of 1982. The court in South Africa under the guidance of the ILO convention were limited to two possible ways of dealing with automatically unfair dismissals. One was to criminalize the practice, and other was to ensure that such dismissals were considered unacceptable.
- Full Text: false
- Date Issued: 2018
Bacterial colonisation and degradation of geologically weathered and discard coal
- Authors: Olawale, Jacob Taiwo
- Date: 2018
- Subjects: Coal mine waste , Coal -- Biodegradation , Coal mines and mining -- Environmental aspects , Land degradation , Electron microscopy , Extracellular polymeric substances , Flagella (Microbiology) , Fourier transform infrared spectroscopy , Microbiologically influenced corrosion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61625 , vital:28043
- Description: Bacterial beneficiation of low-grade coal, coal discard, and waste has the potential to mitigate land degradation, water and soil pollution and, be a strategy for mining companies to responsibly extract and process coal with environmental sustainability. This study investigated the colonisation and biodegradation or depolymerisation of coal discard and geologically weathered coal by selected strains of bacteria, and an attempt has been made to describe the mechanisms associated with colonisation and biodegradation of this carbonaceous material. Ten bacterial strains, Bacillus strain ECCN 18b, Citrobacter strain ECCN 19b, Proteus strain ECCN 20b, Exiguobacterium strain ECCN 21b, Microbacterium strain ECCN 22b, Proteus strain ECCN 23b, Serratia strain ECCN 24b, Escherichia strain ECCN 25b, Bacillus strain ECCN 26b and Bacillus strain ECCN 41b, isolated from diesel-contaminated soil and coal slurry and identified using DNA sequencing, were rescreened and their coal biodegradation potential ranked. The ranking of the bacterial strains was undertaken using several indicators including; formation of brown halos on the plate culture (solid), change in colour intensity of the medium in liquid culture, change in culture media pH, and an increase in absorbance at 280nm and 450nm. Although, all the ten strains showed evidence of biodegradation of coal discard and geologically weathered coal based on the ranking employed, and the three strains considered the best candidates were Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. The actions of the three bacterial strains were further studied and characterised in relation to coal degradation. Electron microscopy revealed that Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b attached to the surface of coal discard and geologically weathered coal by a process that appeared to involve extracellular polymeric substances (EPS), and flagella. The presence of flagella for Citrobacter strain ECCN 19b and Serratia strain ECCN 24b was confirmed by transmission electron microscopy. Bacterial degradation of coal discard and geologically weathered coal by these selected strains resulted in the release of soluble and insoluble products. Ultraviolet/ visible spectrophotometric (UV/VIS) analysis revealed that the soluble products resembled humic acid-like substances, which was confirmed following Fourier Transform Infrared (FTIR) spectroscopy. Analysis revealed that the coal-derived humic acid-like substances were similar to commercial humic acid extracted from bituminous coal. Elemental analysis of the insoluble product residue after bacterial biodegradation revealed the modification of the chemical compositions of the coal discard and geologically weathered coal substrates. Characterisation of the functional groups of the insoluble product using FTIR spectroscopy indicated changes, with the appearance of new peaks at 1737cm-1, 1366cm-1, 1228cm-1, and 1216cm-1 characteristic of aldehyde, ketones, carboxylic acids, esters, amines, and alkanes. Broad spectra regions of 3500 -3200cm-1, characteristic of alcohol and phenol, were also observed. Together, these results were taken as evidence for increased oxidation of the coal substrates, presumably as a consequence of bacterial catalysed biodegradation of coal discard and geologically weathered coal. During bacterial degradation of coal discard and geologically weathered coal, strains produced extracellular protein, which was detected and further investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE). At least three protein bands with molecular mass 53 kDa, 72 kDa, and 82 kDa were common to the three bacterial strains. Following ammonium sulphate precipitation and gel filtration chromatography, additional bands with molecular mass 16 kDa, 33 kDa, 37 kDa, and 43 kDa were detected. An extracellular laccase activity was detected in cultures of Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. Cytochrome P450 activity was detected in all the bacterial strains in the presence of both coal discard and geologically weathered coal. This is the first time that cytochrome P450 activity has been reported following exposure of these three bacterial strains to a coal substrate. Overall, this research has successfully demonstrated the partial degradation of coal discard and geologically weathered coal by Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b and the release of humic acid-like substances. Thus, the biodegradation process involved adherence to and growth of the bacteria on the surface of coal substrate and appeared to require the formation of alkaline substances and the combined activities of extracellular LAC and cytochrome P450. Since bacterial degradation of low-grade coal and discard appears to be viable, the bacteria isolated in this study can potentially be used either for conversion of discard into valuable chemicals or to mitigate the deleterious effects of stockpiled coal discard on the environment.
- Full Text:
- Date Issued: 2018
- Authors: Olawale, Jacob Taiwo
- Date: 2018
- Subjects: Coal mine waste , Coal -- Biodegradation , Coal mines and mining -- Environmental aspects , Land degradation , Electron microscopy , Extracellular polymeric substances , Flagella (Microbiology) , Fourier transform infrared spectroscopy , Microbiologically influenced corrosion
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61625 , vital:28043
- Description: Bacterial beneficiation of low-grade coal, coal discard, and waste has the potential to mitigate land degradation, water and soil pollution and, be a strategy for mining companies to responsibly extract and process coal with environmental sustainability. This study investigated the colonisation and biodegradation or depolymerisation of coal discard and geologically weathered coal by selected strains of bacteria, and an attempt has been made to describe the mechanisms associated with colonisation and biodegradation of this carbonaceous material. Ten bacterial strains, Bacillus strain ECCN 18b, Citrobacter strain ECCN 19b, Proteus strain ECCN 20b, Exiguobacterium strain ECCN 21b, Microbacterium strain ECCN 22b, Proteus strain ECCN 23b, Serratia strain ECCN 24b, Escherichia strain ECCN 25b, Bacillus strain ECCN 26b and Bacillus strain ECCN 41b, isolated from diesel-contaminated soil and coal slurry and identified using DNA sequencing, were rescreened and their coal biodegradation potential ranked. The ranking of the bacterial strains was undertaken using several indicators including; formation of brown halos on the plate culture (solid), change in colour intensity of the medium in liquid culture, change in culture media pH, and an increase in absorbance at 280nm and 450nm. Although, all the ten strains showed evidence of biodegradation of coal discard and geologically weathered coal based on the ranking employed, and the three strains considered the best candidates were Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. The actions of the three bacterial strains were further studied and characterised in relation to coal degradation. Electron microscopy revealed that Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b attached to the surface of coal discard and geologically weathered coal by a process that appeared to involve extracellular polymeric substances (EPS), and flagella. The presence of flagella for Citrobacter strain ECCN 19b and Serratia strain ECCN 24b was confirmed by transmission electron microscopy. Bacterial degradation of coal discard and geologically weathered coal by these selected strains resulted in the release of soluble and insoluble products. Ultraviolet/ visible spectrophotometric (UV/VIS) analysis revealed that the soluble products resembled humic acid-like substances, which was confirmed following Fourier Transform Infrared (FTIR) spectroscopy. Analysis revealed that the coal-derived humic acid-like substances were similar to commercial humic acid extracted from bituminous coal. Elemental analysis of the insoluble product residue after bacterial biodegradation revealed the modification of the chemical compositions of the coal discard and geologically weathered coal substrates. Characterisation of the functional groups of the insoluble product using FTIR spectroscopy indicated changes, with the appearance of new peaks at 1737cm-1, 1366cm-1, 1228cm-1, and 1216cm-1 characteristic of aldehyde, ketones, carboxylic acids, esters, amines, and alkanes. Broad spectra regions of 3500 -3200cm-1, characteristic of alcohol and phenol, were also observed. Together, these results were taken as evidence for increased oxidation of the coal substrates, presumably as a consequence of bacterial catalysed biodegradation of coal discard and geologically weathered coal. During bacterial degradation of coal discard and geologically weathered coal, strains produced extracellular protein, which was detected and further investigated using sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS- PAGE). At least three protein bands with molecular mass 53 kDa, 72 kDa, and 82 kDa were common to the three bacterial strains. Following ammonium sulphate precipitation and gel filtration chromatography, additional bands with molecular mass 16 kDa, 33 kDa, 37 kDa, and 43 kDa were detected. An extracellular laccase activity was detected in cultures of Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b. Cytochrome P450 activity was detected in all the bacterial strains in the presence of both coal discard and geologically weathered coal. This is the first time that cytochrome P450 activity has been reported following exposure of these three bacterial strains to a coal substrate. Overall, this research has successfully demonstrated the partial degradation of coal discard and geologically weathered coal by Citrobacter strain ECCN 19b, Exiguobacterium strain ECCN 21b and Serratia strain ECCN 24b and the release of humic acid-like substances. Thus, the biodegradation process involved adherence to and growth of the bacteria on the surface of coal substrate and appeared to require the formation of alkaline substances and the combined activities of extracellular LAC and cytochrome P450. Since bacterial degradation of low-grade coal and discard appears to be viable, the bacteria isolated in this study can potentially be used either for conversion of discard into valuable chemicals or to mitigate the deleterious effects of stockpiled coal discard on the environment.
- Full Text:
- Date Issued: 2018
Baculovirus synergism: investigating mixed alphabaculovirus and betabaculovirus infections in the false codling moth, thaumatotibia leucotreta, for improved pest control
- Authors: Jukes, Michael David
- Date: 2018
- Subjects: Baculoviruses , Cryptophlebia leucotreta -- Biological control , Citrus -- Diseases and pests -- South Africa , Pests -- Integrated control , Nucleopolyhedroviruses , Natural pesticides , Cryptophlebia leucotreta granulovirus (CrleGV)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61797 , vital:28061
- Description: Baculovirus based biopesticides are an effective and environmentally friendly approach for the control of agriculturally important insect pests. The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is indigenous to southern Africa and is a major pest of citrus crops. This moth poses a serious risk to export of fruit to foreign markets and the control of this pest is therefore imperative. The Cryptophlebia leucotreta granulovirus (CrleGV) has been commercially formulated into the products Cryptogran™ and Cryptex®. These products have been used successfully for over a decade as part of a rigorous integrated pest management (IPM) programme to control T. leucotreta in South Africa. There is however, a continuous need to improve this programme while also addressing new challenges as they arise. An example of a rising concern is the possibility of resistance developing towards CrleGV. This was seen in Europe with field populations of the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), which developed resistance to the Mexican isolate of the Cydia pomonella granulovirus (CpGV-M). To prevent such a scenario occurring in South Africa, there is a need to improve existing methods of control. For example, additional baculovirus variants can be isolated and characterised for determining virulence, which can then be developed as new biopesticides. Additionally, the potential for synergistic effects between different baculoviruses infecting the same host can be explored for improved virulence. A novel nucleopolyhedrovirus was recently identified in T. leucotreta larval homogenates which were also infected with CrleGV. This provided unique opportunities for continued research and development. In this study, a method using C. pomonella larvae, which can be infected by the NPV but not by CrleGV, was developed to separate the NPV from GV-NPV mixtures in an in vivo system. Examination of NPV OBs by transmission electron microscopy showed purified occlusion bodies with a single nucleopolyhedrovirus morphology (SNPV). Genetic characterisation identified the novel NPV as Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), which was recently isolated from the litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae). To begin examining the potential for synergism between the two viruses, a multiplex PCR assay was developed to accurately detect CrleGV and/or CrpeNPV in mixed infections. This assay was applied to various samples to screen for the presence of CrpeNPV and CrleGV. Additionally, a validation experiment was performed using different combinations of CrpeNPV and/or CrleGV to evaluate the effectiveness of the mPCR assay. The results obtained indicated a high degree of specificity with the correct amplicons generated for each test sample. The biological activity of CrpeNPV and CrleGV were evaluated using surface dose bioassays, both individually and in various combinations, against T. leucotreta neonate larvae in a laboratory setting. A synergistic effect was recorded in the combination treatments, showing improved virulence when compared against each virus in isolation. The LC90 for CrpeNPV and CrleGV when applied alone against T. leucotreta was calculated to be 2.75*106 and 3.00*106 OBs.ml"1 respectively. These values decreased to 1.07*106 and 7.18*105 OBs.ml"1 when combinations of CrleGV and CrpeNPV were applied at ratios of 3:1 and 1:3 respectively. These results indicate a potential for developing improved biopesticides for the control of T. leucotreta in the field. To better understand the interactions between CrleGV and CrpeNPV, experiments involving the serial passage of these viruses through T. leucotreta larvae were performed. This was done using each virus in isolation as well as both viruses in different combinations. Genomic DNA was extracted from recovered occlusion bodies after each passage and examined by multiplex and quantitative PCR. This analysis enabled the detection of each virus present throughout this assay, as well as recording shifts in the ratio of CrleGV and CrpeNPV at each passage. CrleGV rapidly became the dominant virus in all treatments, indicating a potentially antagonistic interaction during serial passage. Additionally, CrpeNPV and CrleGV were detected in treatments which were not originally inoculated with one or either virus, indicating potential covert infections in T. leucotreta. Occlusion bodies recovered from the final passage were used to inoculate C. pomonella larvae to isolate CrpeNPV from CrleGV. Genomic DNA was extracted from these CrpeNPV OBs and examined by restriction endonuclease assays and next generation sequencing. This enabled the identification of potential recombination events which may have occurred during the dual GV and NPV infections throughout the passage assay. No recombination events were identified in the CrpeNPV genome sequences assembled from virus collected at the end of the passage assay. Lastly, the efficacy of CrpeNPV and CrleGV, both alone and in various combinations, was evaluated in the field. In two separate trials conducted on citrus, unfavorable field conditions resulted in no significant reduction in fruit infestation for both the virus and chemical treatments. While not statistically significant, virus treatments were recorded to have the lowest levels of fruit infestation with a measured reduction of up to 64 %. This study is the first to report a synergistic effect between CrleGV and CrpeNPV in T. leucotreta. The discovery of beneficial interactions creates an opportunity for the development of novel biopesticides for improved control of this pest in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Jukes, Michael David
- Date: 2018
- Subjects: Baculoviruses , Cryptophlebia leucotreta -- Biological control , Citrus -- Diseases and pests -- South Africa , Pests -- Integrated control , Nucleopolyhedroviruses , Natural pesticides , Cryptophlebia leucotreta granulovirus (CrleGV)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/61797 , vital:28061
- Description: Baculovirus based biopesticides are an effective and environmentally friendly approach for the control of agriculturally important insect pests. The false codling moth (FCM), Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), is indigenous to southern Africa and is a major pest of citrus crops. This moth poses a serious risk to export of fruit to foreign markets and the control of this pest is therefore imperative. The Cryptophlebia leucotreta granulovirus (CrleGV) has been commercially formulated into the products Cryptogran™ and Cryptex®. These products have been used successfully for over a decade as part of a rigorous integrated pest management (IPM) programme to control T. leucotreta in South Africa. There is however, a continuous need to improve this programme while also addressing new challenges as they arise. An example of a rising concern is the possibility of resistance developing towards CrleGV. This was seen in Europe with field populations of the codling moth, Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae), which developed resistance to the Mexican isolate of the Cydia pomonella granulovirus (CpGV-M). To prevent such a scenario occurring in South Africa, there is a need to improve existing methods of control. For example, additional baculovirus variants can be isolated and characterised for determining virulence, which can then be developed as new biopesticides. Additionally, the potential for synergistic effects between different baculoviruses infecting the same host can be explored for improved virulence. A novel nucleopolyhedrovirus was recently identified in T. leucotreta larval homogenates which were also infected with CrleGV. This provided unique opportunities for continued research and development. In this study, a method using C. pomonella larvae, which can be infected by the NPV but not by CrleGV, was developed to separate the NPV from GV-NPV mixtures in an in vivo system. Examination of NPV OBs by transmission electron microscopy showed purified occlusion bodies with a single nucleopolyhedrovirus morphology (SNPV). Genetic characterisation identified the novel NPV as Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), which was recently isolated from the litchi moth, Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae). To begin examining the potential for synergism between the two viruses, a multiplex PCR assay was developed to accurately detect CrleGV and/or CrpeNPV in mixed infections. This assay was applied to various samples to screen for the presence of CrpeNPV and CrleGV. Additionally, a validation experiment was performed using different combinations of CrpeNPV and/or CrleGV to evaluate the effectiveness of the mPCR assay. The results obtained indicated a high degree of specificity with the correct amplicons generated for each test sample. The biological activity of CrpeNPV and CrleGV were evaluated using surface dose bioassays, both individually and in various combinations, against T. leucotreta neonate larvae in a laboratory setting. A synergistic effect was recorded in the combination treatments, showing improved virulence when compared against each virus in isolation. The LC90 for CrpeNPV and CrleGV when applied alone against T. leucotreta was calculated to be 2.75*106 and 3.00*106 OBs.ml"1 respectively. These values decreased to 1.07*106 and 7.18*105 OBs.ml"1 when combinations of CrleGV and CrpeNPV were applied at ratios of 3:1 and 1:3 respectively. These results indicate a potential for developing improved biopesticides for the control of T. leucotreta in the field. To better understand the interactions between CrleGV and CrpeNPV, experiments involving the serial passage of these viruses through T. leucotreta larvae were performed. This was done using each virus in isolation as well as both viruses in different combinations. Genomic DNA was extracted from recovered occlusion bodies after each passage and examined by multiplex and quantitative PCR. This analysis enabled the detection of each virus present throughout this assay, as well as recording shifts in the ratio of CrleGV and CrpeNPV at each passage. CrleGV rapidly became the dominant virus in all treatments, indicating a potentially antagonistic interaction during serial passage. Additionally, CrpeNPV and CrleGV were detected in treatments which were not originally inoculated with one or either virus, indicating potential covert infections in T. leucotreta. Occlusion bodies recovered from the final passage were used to inoculate C. pomonella larvae to isolate CrpeNPV from CrleGV. Genomic DNA was extracted from these CrpeNPV OBs and examined by restriction endonuclease assays and next generation sequencing. This enabled the identification of potential recombination events which may have occurred during the dual GV and NPV infections throughout the passage assay. No recombination events were identified in the CrpeNPV genome sequences assembled from virus collected at the end of the passage assay. Lastly, the efficacy of CrpeNPV and CrleGV, both alone and in various combinations, was evaluated in the field. In two separate trials conducted on citrus, unfavorable field conditions resulted in no significant reduction in fruit infestation for both the virus and chemical treatments. While not statistically significant, virus treatments were recorded to have the lowest levels of fruit infestation with a measured reduction of up to 64 %. This study is the first to report a synergistic effect between CrleGV and CrpeNPV in T. leucotreta. The discovery of beneficial interactions creates an opportunity for the development of novel biopesticides for improved control of this pest in South Africa.
- Full Text:
- Date Issued: 2018
Balancing the interests of employer and employee in dismissal for misconduct
- Pillay, Prushothman Subramoney
- Authors: Pillay, Prushothman Subramoney
- Date: 2018
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Labor discipline -- Law and legislation -- South Africa South Africa -- Employment Equity Act, 1998 South Africa -- Basic Conditions of Employment Act, 1997 South Africa -- Labour Relations Act, 1995 Unfair labor practices -- South Africa Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/34414 , vital:33375
- Description: South Africa emerged from a history dogged by an oppressive system in which race was used as a medium of oppression. Workers and in particular African workers’ rights were severely curtailed. However, following the advent of the Constitution, several employees’ rights and freedoms are now entrenched key amongst them in the right to fair labour practices is enshrined in section 23 (1) of the Constitution. Post 1994, South Africa adopted various new forms of labour legislation, including the Labour Relations Act. This marked the watershed in changing the balance of power away from the employer. The LRA gives form and content to the rights enshrined in the Constitution by establishing substantive and procedural requirements prior to dismissal. Equally important is the guidelines contained in schedule 8 to the LRA which depict an attempt by the legislature to ensure that employees are protected against unfair dismissal. The historical background of the employment relationship stems from the Master and Servant Act. The common law evolved in South Africa from Roman-Dutch and English practices. The common law was shaped against the backdrop of Apartheid modified to some extent through the Wiehahn Commission4 and more recently politically through union and National Economic Development and Labour Council (NEDLAC) involvement regulating labour practices through legislation. In South Africa, the employment relationship is regulated by three main sources of law. These include the Constitution, labour legislation and the law of contract. Besides these sources, South Africa is a member state of the International Labour Organisation.
- Full Text:
- Date Issued: 2018
- Authors: Pillay, Prushothman Subramoney
- Date: 2018
- Subjects: Employees -- Dismissal of -- Law and legislation -- South Africa , Labor discipline -- Law and legislation -- South Africa South Africa -- Employment Equity Act, 1998 South Africa -- Basic Conditions of Employment Act, 1997 South Africa -- Labour Relations Act, 1995 Unfair labor practices -- South Africa Labor laws and legislation -- South Africa
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/34414 , vital:33375
- Description: South Africa emerged from a history dogged by an oppressive system in which race was used as a medium of oppression. Workers and in particular African workers’ rights were severely curtailed. However, following the advent of the Constitution, several employees’ rights and freedoms are now entrenched key amongst them in the right to fair labour practices is enshrined in section 23 (1) of the Constitution. Post 1994, South Africa adopted various new forms of labour legislation, including the Labour Relations Act. This marked the watershed in changing the balance of power away from the employer. The LRA gives form and content to the rights enshrined in the Constitution by establishing substantive and procedural requirements prior to dismissal. Equally important is the guidelines contained in schedule 8 to the LRA which depict an attempt by the legislature to ensure that employees are protected against unfair dismissal. The historical background of the employment relationship stems from the Master and Servant Act. The common law evolved in South Africa from Roman-Dutch and English practices. The common law was shaped against the backdrop of Apartheid modified to some extent through the Wiehahn Commission4 and more recently politically through union and National Economic Development and Labour Council (NEDLAC) involvement regulating labour practices through legislation. In South Africa, the employment relationship is regulated by three main sources of law. These include the Constitution, labour legislation and the law of contract. Besides these sources, South Africa is a member state of the International Labour Organisation.
- Full Text:
- Date Issued: 2018
Barriers and drivers to the implementation of renewable energy technologies in South Africa’s aquaculture industry
- Authors: Van Wyk, Nicholas Kelly
- Date: 2018
- Subjects: Renewable energy sources South Africa , Aquaculture Environmental aspects South Africa , Sustainable aquaculture Economic aspects South Africa , Renewable energy sources Economic aspects South Africa , Renewable energy sources Environmental aspects South Africa
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/61969 , vital:28090
- Description: South Africa is plagued by socio-economic issues of poverty, inequality and high rates of unemployment. The government of South Africa has as such launched an ambitious plan known as operation PHAKISA which will complement the National Development Plan in addressing the countries aforementioned shortcomings. In the operations first phase, the focus is on growing South Africa’s ocean economy. Within the ocean economy, the growth of aquaculture has been identified as an industry with the potential to create jobs and aid in economic growth of South Africa. Aquaculture, the farming of any aquatic organisms, has been the fastest growing food production sector for the past 50 years. While natural capture fisheries have stagnated in production capacity, aquaculture has grown exponentially in order to feed a global population which is fast approaching nine billion people. However, South Africa’s aquaculture production lags significantly behind other third world countries. The sustainability of aquaculture has frequently been called into question due to the possibility of various detrimental environmental effects it may cause. To further complicate the matter, Climate Change is today an overarching threat to life as we know it, and must be taken into account if we plan to keep growing our populations and economies. As such, if South Africa wants to grow its aquaculture sector, it must be done so in a sustainable manner. This research thus sought to investigate one aspect which may increase the sustainability of aquaculture in South Africa, that being the implementation of renewable energy in the sector. Renewable energy has been identified by the United Nations Intergovernmental Panel on Climate Change as key to mitigating the effects of climate change. In order to aid Renewable Energy (RE) implementation in South Africa’s aquaculture sector, this research aimed to identify the barriers and the drivers to implementing renewable energy within aquaculture. To do this, a literature review was conducted to identify possible barriers and drivers to renewable energy implementation. These were then drafted into an online questionnaire and sent via Email to all the aquaculture organisations in South Africa that could be contacted (n = 195). Respondents were asked to rank the proposed barriers and drivers to renewable energy according to their perceived importance on a Likert Scale. A total of 18 responses could be analysed with descriptive statistics. Further, three structured interviews were conducted with members of South African aquaculture organisations who had implemented some form of Renewable Energy Technology (RET). These interviews provided in-depth insights into the importance of the various proposed barriers and drivers. The results revealed the most important barriers to RE implementation were: High Initial investments, Utility monopoly of production, Lack of RE experts on a governmental level, Lack of incentives/subsidies from government, Lack of legal framework for Independent Power Producers and Power Purchase Agreements, and Diseconomy of scale respectively. The most important drivers to RE implementation were ranked as: Long term cost benefits, Reduction in cost of RETs, Innovation / advancement of RETS, Incentives or subsidies to implement renewable energy, Adequate legal framework and legislation for Power Purchase Agreement and Preference for environmentally-friendly electricity generation. Importantly, it was found that barriers and drivers are dependent on the type of RE being implemented. A Photo Voltaic (Solar Power) system will not necessarily experience the same barriers or drivers that a Wave Energy Converter system would. In order to drive investment in RE and remove the barriers that may be preventing its implementation in aquaculture, policy will have to be adapted. Particularly in terms of legislation around Power Purchase Agreements. Further, by providing subsidies for RE implementation, it is possible to sustainably grow South Africa’s aquaculture industry.
- Full Text:
- Date Issued: 2018
- Authors: Van Wyk, Nicholas Kelly
- Date: 2018
- Subjects: Renewable energy sources South Africa , Aquaculture Environmental aspects South Africa , Sustainable aquaculture Economic aspects South Africa , Renewable energy sources Economic aspects South Africa , Renewable energy sources Environmental aspects South Africa
- Language: English
- Type: text , Thesis , Masters , MBA
- Identifier: http://hdl.handle.net/10962/61969 , vital:28090
- Description: South Africa is plagued by socio-economic issues of poverty, inequality and high rates of unemployment. The government of South Africa has as such launched an ambitious plan known as operation PHAKISA which will complement the National Development Plan in addressing the countries aforementioned shortcomings. In the operations first phase, the focus is on growing South Africa’s ocean economy. Within the ocean economy, the growth of aquaculture has been identified as an industry with the potential to create jobs and aid in economic growth of South Africa. Aquaculture, the farming of any aquatic organisms, has been the fastest growing food production sector for the past 50 years. While natural capture fisheries have stagnated in production capacity, aquaculture has grown exponentially in order to feed a global population which is fast approaching nine billion people. However, South Africa’s aquaculture production lags significantly behind other third world countries. The sustainability of aquaculture has frequently been called into question due to the possibility of various detrimental environmental effects it may cause. To further complicate the matter, Climate Change is today an overarching threat to life as we know it, and must be taken into account if we plan to keep growing our populations and economies. As such, if South Africa wants to grow its aquaculture sector, it must be done so in a sustainable manner. This research thus sought to investigate one aspect which may increase the sustainability of aquaculture in South Africa, that being the implementation of renewable energy in the sector. Renewable energy has been identified by the United Nations Intergovernmental Panel on Climate Change as key to mitigating the effects of climate change. In order to aid Renewable Energy (RE) implementation in South Africa’s aquaculture sector, this research aimed to identify the barriers and the drivers to implementing renewable energy within aquaculture. To do this, a literature review was conducted to identify possible barriers and drivers to renewable energy implementation. These were then drafted into an online questionnaire and sent via Email to all the aquaculture organisations in South Africa that could be contacted (n = 195). Respondents were asked to rank the proposed barriers and drivers to renewable energy according to their perceived importance on a Likert Scale. A total of 18 responses could be analysed with descriptive statistics. Further, three structured interviews were conducted with members of South African aquaculture organisations who had implemented some form of Renewable Energy Technology (RET). These interviews provided in-depth insights into the importance of the various proposed barriers and drivers. The results revealed the most important barriers to RE implementation were: High Initial investments, Utility monopoly of production, Lack of RE experts on a governmental level, Lack of incentives/subsidies from government, Lack of legal framework for Independent Power Producers and Power Purchase Agreements, and Diseconomy of scale respectively. The most important drivers to RE implementation were ranked as: Long term cost benefits, Reduction in cost of RETs, Innovation / advancement of RETS, Incentives or subsidies to implement renewable energy, Adequate legal framework and legislation for Power Purchase Agreement and Preference for environmentally-friendly electricity generation. Importantly, it was found that barriers and drivers are dependent on the type of RE being implemented. A Photo Voltaic (Solar Power) system will not necessarily experience the same barriers or drivers that a Wave Energy Converter system would. In order to drive investment in RE and remove the barriers that may be preventing its implementation in aquaculture, policy will have to be adapted. Particularly in terms of legislation around Power Purchase Agreements. Further, by providing subsidies for RE implementation, it is possible to sustainably grow South Africa’s aquaculture industry.
- Full Text:
- Date Issued: 2018
Barriers to picking and packing in pharmaceutical warehousing and distribution in South Africa
- Authors: Kemp, Nicholas
- Date: 2018
- Subjects: Pharmaceutical industry -- Materials management , Warehouses -- Management Pharmaceutical industry -- South Africa Physical distribution of goods -- Management
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/30627 , vital:30994
- Description: Barriers within the supply chain play an evident role in decreasing its efficiency. The supply chain system is not well documented in the pharmaceutical sector. The aim of this study was to identify any barriers to the movement of picking and packing operators within 6 distribution facilities throughout South Africa using a time and motion analysis. A pilot study was initially conducted to choose the stopwatch application for Android® devices and to ensure reliability of the tools utilised. The motions during the processes of fulfilling an order were identified during the case picking, bulk picking and packing processes by direct observation of operators. The direct observation was performed using a stopwatch application for Android® devices and a tool on Microsoft Excel®. The data was analysed using Microsoft Excel®, using a student’s T-test and an analysis of variance (ANOVA) approach to identify similarities and differences between the facilities. The data was further analysed using a descriptive statistics approach to identify the common barriers amongst the distribution centres. Thereafter, the data was analysed by identifying a value-quotient. The value-quotient was used to identify how much time was spent on value-adding activities with each facility. The observation of the operators was done randomly at each facility to avoid subjectivity and bias. Results: The pilot study identified which stopwatch application was to be utilised. The pilot study aided to improve upon the design of the data collection tool used for the transcribing of the timing operation. The student’s T-test and ANOVA revealed that there were statistically significant differences in case picking amongst facilities, namely using the radio frequency identification devices (RFID), picking and transfer of stock. In the bulk picking process, there was a statistically significant difference amongst the facilities, namely using the RFID, pick and transfer of stock. In the packing process there was a statistically significant difference amongst the facilities in the packing process. The analysis of barriers within the distribution centres revealed that the 16 common barriers amongst the picking processes at the facilities included raising the platform, waiting for colleagues to depart an aisle, RFID malfunctions and answering their phones. No common barriers during the packing process was identified. The value-quotient revealed that most of the facilities spent more than 50 percent of their time on value-adding activities during the case picking, bulk picking and packing processes. A time and motion analysis proved to be an effective method to identify similarities and barriers between the six facilities. It was recommended to investigate a few of the basic operations to improve upon, as well as the possibility of implementing a barcoded system to the stock.
- Full Text:
- Date Issued: 2018
- Authors: Kemp, Nicholas
- Date: 2018
- Subjects: Pharmaceutical industry -- Materials management , Warehouses -- Management Pharmaceutical industry -- South Africa Physical distribution of goods -- Management
- Language: English
- Type: Thesis , Masters , MPharm
- Identifier: http://hdl.handle.net/10948/30627 , vital:30994
- Description: Barriers within the supply chain play an evident role in decreasing its efficiency. The supply chain system is not well documented in the pharmaceutical sector. The aim of this study was to identify any barriers to the movement of picking and packing operators within 6 distribution facilities throughout South Africa using a time and motion analysis. A pilot study was initially conducted to choose the stopwatch application for Android® devices and to ensure reliability of the tools utilised. The motions during the processes of fulfilling an order were identified during the case picking, bulk picking and packing processes by direct observation of operators. The direct observation was performed using a stopwatch application for Android® devices and a tool on Microsoft Excel®. The data was analysed using Microsoft Excel®, using a student’s T-test and an analysis of variance (ANOVA) approach to identify similarities and differences between the facilities. The data was further analysed using a descriptive statistics approach to identify the common barriers amongst the distribution centres. Thereafter, the data was analysed by identifying a value-quotient. The value-quotient was used to identify how much time was spent on value-adding activities with each facility. The observation of the operators was done randomly at each facility to avoid subjectivity and bias. Results: The pilot study identified which stopwatch application was to be utilised. The pilot study aided to improve upon the design of the data collection tool used for the transcribing of the timing operation. The student’s T-test and ANOVA revealed that there were statistically significant differences in case picking amongst facilities, namely using the radio frequency identification devices (RFID), picking and transfer of stock. In the bulk picking process, there was a statistically significant difference amongst the facilities, namely using the RFID, pick and transfer of stock. In the packing process there was a statistically significant difference amongst the facilities in the packing process. The analysis of barriers within the distribution centres revealed that the 16 common barriers amongst the picking processes at the facilities included raising the platform, waiting for colleagues to depart an aisle, RFID malfunctions and answering their phones. No common barriers during the packing process was identified. The value-quotient revealed that most of the facilities spent more than 50 percent of their time on value-adding activities during the case picking, bulk picking and packing processes. A time and motion analysis proved to be an effective method to identify similarities and barriers between the six facilities. It was recommended to investigate a few of the basic operations to improve upon, as well as the possibility of implementing a barcoded system to the stock.
- Full Text:
- Date Issued: 2018
Bayesian hierarchical modelling with application in spatial epidemiology
- Authors: Southey, Richard Robert
- Date: 2018
- Subjects: Bayesian statistical decision theory , Spatial analysis (Statistics) , Medical mapping , Pericarditis , Mortality Statistics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59489 , vital:27617
- Description: Disease mapping and spatial statistics have become an important part of modern day statistics and have increased in popularity as the methods and techniques have evolved. The application of disease mapping is not only confined to the analysis of diseases as other applications of disease mapping can be found in Econometric and financial disciplines. This thesis will consider two data sets. These are the Georgia oral cancer 2004 data set and the South African acute pericarditis 2014 data set. The Georgia data set will be used to assess the hyperprior sensitivity of the precision for the uncorrelated heterogeneity and correlated heterogeneity components in a convolution model. The correlated heterogeneity will be modelled by a conditional autoregressive prior distribution and the uncorrelated heterogeneity will be modelled with a zero mean Gaussian prior distribution. The sensitivity analysis will be performed using three models with conjugate, Jeffreys' and a fixed parameter prior for the hyperprior distribution of the precision for the uncorrelated heterogeneity component. A simulation study will be done to compare four prior distributions which will be the conjugate, Jeffreys', probability matching and divergence priors. The three models will be fitted in WinBUGS® using a Bayesian approach. The results of the three models will be in the form of disease maps, figures and tables. The results show that the hyperprior of the precision for the uncorrelated heterogeneity and correlated heterogeneity components are sensitive to changes and will result in different results depending on the specification of the hyperprior distribution of the precision for the two components in the model. The South African data set will be used to examine whether there is a difference between the proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the correlated heterogeneity component in a convolution model. Two models will be fitted in WinBUGS® for this comparison. Both the hyperpriors of the precision for the uncorrelated heterogeneity and correlated heterogeneity components will be modelled using a Jeffreys' prior distribution. The results show that there is no significant difference between the results of the model with a proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the South African data, although there are a few disadvantages of using a proper conditional autoregressive prior for the correlated heterogeneity which will be stated in the conclusion.
- Full Text:
- Date Issued: 2018
- Authors: Southey, Richard Robert
- Date: 2018
- Subjects: Bayesian statistical decision theory , Spatial analysis (Statistics) , Medical mapping , Pericarditis , Mortality Statistics
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/59489 , vital:27617
- Description: Disease mapping and spatial statistics have become an important part of modern day statistics and have increased in popularity as the methods and techniques have evolved. The application of disease mapping is not only confined to the analysis of diseases as other applications of disease mapping can be found in Econometric and financial disciplines. This thesis will consider two data sets. These are the Georgia oral cancer 2004 data set and the South African acute pericarditis 2014 data set. The Georgia data set will be used to assess the hyperprior sensitivity of the precision for the uncorrelated heterogeneity and correlated heterogeneity components in a convolution model. The correlated heterogeneity will be modelled by a conditional autoregressive prior distribution and the uncorrelated heterogeneity will be modelled with a zero mean Gaussian prior distribution. The sensitivity analysis will be performed using three models with conjugate, Jeffreys' and a fixed parameter prior for the hyperprior distribution of the precision for the uncorrelated heterogeneity component. A simulation study will be done to compare four prior distributions which will be the conjugate, Jeffreys', probability matching and divergence priors. The three models will be fitted in WinBUGS® using a Bayesian approach. The results of the three models will be in the form of disease maps, figures and tables. The results show that the hyperprior of the precision for the uncorrelated heterogeneity and correlated heterogeneity components are sensitive to changes and will result in different results depending on the specification of the hyperprior distribution of the precision for the two components in the model. The South African data set will be used to examine whether there is a difference between the proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the correlated heterogeneity component in a convolution model. Two models will be fitted in WinBUGS® for this comparison. Both the hyperpriors of the precision for the uncorrelated heterogeneity and correlated heterogeneity components will be modelled using a Jeffreys' prior distribution. The results show that there is no significant difference between the results of the model with a proper conditional autoregressive prior and intrinsic conditional autoregressive prior for the South African data, although there are a few disadvantages of using a proper conditional autoregressive prior for the correlated heterogeneity which will be stated in the conclusion.
- Full Text:
- Date Issued: 2018
Bayesian spatial modelling of tuberculosis and its effects on socio-economic and demographic factors in South Africa : a case study of the Eastern Cape Province
- Authors: Obaromi, Abiodun Davies
- Date: 2018
- Subjects: Tuberculosis -- South Africa -- Eastern Cape Tuberculosis -- Epidemiology -- Statistics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9648 , vital:34813
- Description: This dissertation is concerned with evolving and extending statistical models in the area of Bayesian spatial modelling, an increasingly important field of spatial epidemiology with particular interest towards application to Tuberculosis data in the Eastern Cape province of South Africa. In spatial epidemiology, the diseases to be examined usually occur within a map that needs spatial statistical methods that are appropriate, to model the observed data in the presence of some covariates and also cater for the variation of the disease. In this thesis, the Bayesian models were developed in such a way that they allowed several factors classified as fixed and random effects, to be included in the models and using the Bayesian approach. The basic model used in disease mapping is the Besag, York and Mollie model, which incorporates two random effects; one which is spatially structured and the other random effect which is spatially unstructured. The effects (fixed and random) were the covariate effects, socio-economic and demographic variability and the spatial variability respectively, which were all investigated in seven different hierarchical/multilevel Bayesian models. These factors showed varying and substantial effects in the posterior relative risk estimation of the disease. We assumed a negative binomial and generalized Poisson distributions to the response variable or relative risk estimate, 𝑦𝑖 ,to capture the over-dispersion phenomenon that is common and inherent with Poisson density for counts data. Spatial and non-spatial models were developed to model over-dispersion with all the distributions; Poisson, negative binomial and generalized Poisson. Negative binomial and generalized Poisson showed varying properties from comparisons with DIC values and parameter estimates to standard errors, which made either of them fit depending on the choice of model selection. It was found that a lower DIC value could be insufficient to determine a best fit model, if other models present estimates with lower variances even at higher DIC values. The generalized Poisson, a two parameter distribution like the negative binomial, which also has the ability to capture both under-dispersion and over-dispersion, was found to perform better in the results than the negative binomial on the basis of a lower variance and with more exact parameter estimates. A new weighted prior distribution, the “Besag2” ICAR model for the structured spatial random effects, which is an extension of the traditional ICAR prior model with two hyperparameters, was also developed and compared with some existing prior models; BYM and ICAR, to measure for spatial dependency in the regions. This new prior distribution was found to show a better fit, when compared to the basic ICAR prior usually assumed for the spatial random effect in the BYM model. This newly parameterized prior distribution in the Besag, York and Mollie model also led to improved parameter control, as the hyperparameters can be seen independently from each other. The result also showed that the new model performed well, both presenting good learning abilities and good shrinkage behaviour. In terms of model choice criteria, the proposed model performed at least equally well and better than the existing models, and the new formulation also gave parameters that are interpretable and have a clearer meaning. To interpolate scattered or regularly distributed data, there are imprecise or exact methods, but there are some of these methods that could be used for interpolating data in a regular grid and others in an irregular grid. Linear and biharmonic spline methods were implemented in MATLAB, to compare for smoothing in the distribution patterns of tuberculosis in the province. This smoothing spline is a method of fitting a smooth curve to a set of noisy observations using a spline function. This new method is rarely used in disease mapping applications, but it has a superior advantage to be assessed at subjective locations rather than only on a rectangular grid as seen in most traditional GIS methods of geospatial analyses. The proposed new models and methods in this thesis were found to be flexible and robust, since they can be reduced or extended according to the nature of the data. Nevertheless, great care must be considered in the choice of prior densities. The approaches developed in this dissertation helped to broaden the scope for spatial analysis and disease mapping applications in epidemiology and public health studies.
- Full Text:
- Date Issued: 2018
- Authors: Obaromi, Abiodun Davies
- Date: 2018
- Subjects: Tuberculosis -- South Africa -- Eastern Cape Tuberculosis -- Epidemiology -- Statistics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9648 , vital:34813
- Description: This dissertation is concerned with evolving and extending statistical models in the area of Bayesian spatial modelling, an increasingly important field of spatial epidemiology with particular interest towards application to Tuberculosis data in the Eastern Cape province of South Africa. In spatial epidemiology, the diseases to be examined usually occur within a map that needs spatial statistical methods that are appropriate, to model the observed data in the presence of some covariates and also cater for the variation of the disease. In this thesis, the Bayesian models were developed in such a way that they allowed several factors classified as fixed and random effects, to be included in the models and using the Bayesian approach. The basic model used in disease mapping is the Besag, York and Mollie model, which incorporates two random effects; one which is spatially structured and the other random effect which is spatially unstructured. The effects (fixed and random) were the covariate effects, socio-economic and demographic variability and the spatial variability respectively, which were all investigated in seven different hierarchical/multilevel Bayesian models. These factors showed varying and substantial effects in the posterior relative risk estimation of the disease. We assumed a negative binomial and generalized Poisson distributions to the response variable or relative risk estimate, 𝑦𝑖 ,to capture the over-dispersion phenomenon that is common and inherent with Poisson density for counts data. Spatial and non-spatial models were developed to model over-dispersion with all the distributions; Poisson, negative binomial and generalized Poisson. Negative binomial and generalized Poisson showed varying properties from comparisons with DIC values and parameter estimates to standard errors, which made either of them fit depending on the choice of model selection. It was found that a lower DIC value could be insufficient to determine a best fit model, if other models present estimates with lower variances even at higher DIC values. The generalized Poisson, a two parameter distribution like the negative binomial, which also has the ability to capture both under-dispersion and over-dispersion, was found to perform better in the results than the negative binomial on the basis of a lower variance and with more exact parameter estimates. A new weighted prior distribution, the “Besag2” ICAR model for the structured spatial random effects, which is an extension of the traditional ICAR prior model with two hyperparameters, was also developed and compared with some existing prior models; BYM and ICAR, to measure for spatial dependency in the regions. This new prior distribution was found to show a better fit, when compared to the basic ICAR prior usually assumed for the spatial random effect in the BYM model. This newly parameterized prior distribution in the Besag, York and Mollie model also led to improved parameter control, as the hyperparameters can be seen independently from each other. The result also showed that the new model performed well, both presenting good learning abilities and good shrinkage behaviour. In terms of model choice criteria, the proposed model performed at least equally well and better than the existing models, and the new formulation also gave parameters that are interpretable and have a clearer meaning. To interpolate scattered or regularly distributed data, there are imprecise or exact methods, but there are some of these methods that could be used for interpolating data in a regular grid and others in an irregular grid. Linear and biharmonic spline methods were implemented in MATLAB, to compare for smoothing in the distribution patterns of tuberculosis in the province. This smoothing spline is a method of fitting a smooth curve to a set of noisy observations using a spline function. This new method is rarely used in disease mapping applications, but it has a superior advantage to be assessed at subjective locations rather than only on a rectangular grid as seen in most traditional GIS methods of geospatial analyses. The proposed new models and methods in this thesis were found to be flexible and robust, since they can be reduced or extended according to the nature of the data. Nevertheless, great care must be considered in the choice of prior densities. The approaches developed in this dissertation helped to broaden the scope for spatial analysis and disease mapping applications in epidemiology and public health studies.
- Full Text:
- Date Issued: 2018
Beasts we love
- Authors: Masolane, Tseliso Chrisjan
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Detective and mystery stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63098 , vital:28363
- Description: My thesis is a novella in flash, written as political crime fiction. It is set in contemporary South Africa and tells the story of Rafau Lekopo, a teacher from a little township called Dikgohlong, whose life is changed forever after he finds his wife and the mayor in bed and shoots them both dead. The information contained within the dead mayor's notebook proves to be explosive, showing that the mayor is far more than he seems, and that he is in fact in the employ of a foreign intelligence service. After his release from prison, the embittered Lekopo sets about his revenge against powerful men who abuse their political power. He takes refuge in Lesotho, masterminds a series of heists, car-hijackings and human trafficking, and expands his syndication back in South Africa. Using the contacts and information from the mayor's notebook, he manipulates the Lesotho government into a diplomatic feud with South Africa which treatens to escalate into a military conflict.
- Full Text:
- Date Issued: 2018
- Authors: Masolane, Tseliso Chrisjan
- Date: 2018
- Subjects: Creative writing (Higher education) -- South Africa , South African fiction (English) -- 21st century , Detective and mystery stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63098 , vital:28363
- Description: My thesis is a novella in flash, written as political crime fiction. It is set in contemporary South Africa and tells the story of Rafau Lekopo, a teacher from a little township called Dikgohlong, whose life is changed forever after he finds his wife and the mayor in bed and shoots them both dead. The information contained within the dead mayor's notebook proves to be explosive, showing that the mayor is far more than he seems, and that he is in fact in the employ of a foreign intelligence service. After his release from prison, the embittered Lekopo sets about his revenge against powerful men who abuse their political power. He takes refuge in Lesotho, masterminds a series of heists, car-hijackings and human trafficking, and expands his syndication back in South Africa. Using the contacts and information from the mayor's notebook, he manipulates the Lesotho government into a diplomatic feud with South Africa which treatens to escalate into a military conflict.
- Full Text:
- Date Issued: 2018
Beginner teachers’ leadership development opportunities: an interventionist case study in a rural combined school in the Ohangwena region, Namibia
- Authors: Ndakolonkoshi, Klaudia
- Date: 2018
- Subjects: School management and organization -- Namibia , Teacher participation in administration -- Namibia , Educational leadership -- Namibia , Teacher effectiveness -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61603 , vital:28041
- Description: The emergence of distributed leadership theory encourages multiple involvement of individuals in leadership of the school, regardless of their leadership positions (Spillane, 2006). The manifestation of teacher leadership through distributed leadership theory grants opportunities to teachers to enact leadership roles. This study explored how the notion of teacher leadership is understood, the leadership roles existing for the beginner teachers, and the constraining and enabling factors to the practice of teacher leadership in a rural combined school in Ohangwena region, in Namibia. The study is a formative intervention adopting a case study approach located in a critical paradigm since it aimed to bring changes in the activity system of the beginner teachers. The data were collected from ten participants: four beginner teachers, four experienced teachers, the principal and the Head of Department. The data were generated using the following techniques: document analysis, interview, questionnaires, observation and Change Laboratory workshops. The data were analysed thematically using second generation of Cultural Historical Activity Theory (CHAT) and Grant’s (2006, 2008, 2010) Teacher Leadership Model. The findings revealed that there were different understandings of the concept of teacher leadership. It was viewed as participation, influence, motivation and mentoring. It was also revealed that beginner teachers practiced leadership roles across the four zones of Grant’s (2006, 2008, 2010) Teacher Leadership Model, but to various extents. A high participation was noted in zone one within the classroom and zone two in curricular and extra-curricular activities and minimal participation was reported in zone three within the whole school development and zone four beyond the school into the community. Teacher leadership in the case study school was constrained by several factors, including teachers’ reluctance to lead, cultural beliefs, top-down leadership structure and lack of experience. Due to the minimal participation of beginner teachers in zone three and four, the findings suggested that the school should foster a collaborative culture, establish induction and mentoring committees in the school and encourage beginner teachers to take up leadership roles by providing opportunities for them to lead through delegation. In a series of Change Laboratory workshops (CLW) the principal and the Head of Department took up the responsibility of providing leadership training to the teachers to enable them to assume leadership roles in the school. In addition, participants agreed to establish induction and mentoring committees in the school to provide guidance and assistance to teacher leaders.
- Full Text:
- Date Issued: 2018
- Authors: Ndakolonkoshi, Klaudia
- Date: 2018
- Subjects: School management and organization -- Namibia , Teacher participation in administration -- Namibia , Educational leadership -- Namibia , Teacher effectiveness -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/61603 , vital:28041
- Description: The emergence of distributed leadership theory encourages multiple involvement of individuals in leadership of the school, regardless of their leadership positions (Spillane, 2006). The manifestation of teacher leadership through distributed leadership theory grants opportunities to teachers to enact leadership roles. This study explored how the notion of teacher leadership is understood, the leadership roles existing for the beginner teachers, and the constraining and enabling factors to the practice of teacher leadership in a rural combined school in Ohangwena region, in Namibia. The study is a formative intervention adopting a case study approach located in a critical paradigm since it aimed to bring changes in the activity system of the beginner teachers. The data were collected from ten participants: four beginner teachers, four experienced teachers, the principal and the Head of Department. The data were generated using the following techniques: document analysis, interview, questionnaires, observation and Change Laboratory workshops. The data were analysed thematically using second generation of Cultural Historical Activity Theory (CHAT) and Grant’s (2006, 2008, 2010) Teacher Leadership Model. The findings revealed that there were different understandings of the concept of teacher leadership. It was viewed as participation, influence, motivation and mentoring. It was also revealed that beginner teachers practiced leadership roles across the four zones of Grant’s (2006, 2008, 2010) Teacher Leadership Model, but to various extents. A high participation was noted in zone one within the classroom and zone two in curricular and extra-curricular activities and minimal participation was reported in zone three within the whole school development and zone four beyond the school into the community. Teacher leadership in the case study school was constrained by several factors, including teachers’ reluctance to lead, cultural beliefs, top-down leadership structure and lack of experience. Due to the minimal participation of beginner teachers in zone three and four, the findings suggested that the school should foster a collaborative culture, establish induction and mentoring committees in the school and encourage beginner teachers to take up leadership roles by providing opportunities for them to lead through delegation. In a series of Change Laboratory workshops (CLW) the principal and the Head of Department took up the responsibility of providing leadership training to the teachers to enable them to assume leadership roles in the school. In addition, participants agreed to establish induction and mentoring committees in the school to provide guidance and assistance to teacher leaders.
- Full Text:
- Date Issued: 2018
Behaviour of quiet time ionospheric disturbances at African equatorial and midlatitude regions
- Authors: Orford, Nicola Diane
- Date: 2018
- Subjects: Ionospheric storms , Ionospheric storms -- Africa , Ionosphere , Plasmasphere , Q-disturbances , Total electron content (TEC)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62672 , vital:28228
- Description: Extreme ionospheric and geomagnetic disturbances affect technology adversely. Prestorm enhancements, considered a potential predictor of geomagnetic storms, occur during quiet conditions prior to geomagnetic disturbances. The ionosphere experiences general disturbances during quiet geomagnetic conditions and these Q- disturbances remain unexplored over Africa. This study used TEC data to characterize the morphology of Q-disturbances over Africa, exploring variations with solar cycle, season, time of occurrence and latitude. Observations from 10 African GPS stations in the equatorial and midlatitude regions show that Q-disturbances in the equatorial region are predominantly driven by E x B variations, while multiple mechanisms affect the midlatitude region. Q- disturbances occur more frequently during nighttime than during daytime and no seasonal trend is observed. Midlatitude Q-disturbance mechanisms are explored in depth, considering substorm activity, the plasmaspheric contribution to GPS TEC and plasma transfer between conjugate points. Substorm activity is not a dominant mechanism, although Q-disturbances occurring under elevated substorm conditions tend to have longer duration and larger amplitude than general Q-disturbances. Many observed Q-disturbances become non-significant once the plasmaspheric contribution to the TEC measurements is removed, indicating that these disturbances occur within the plasmasphere, and not the ionosphere. Transfer of plasma between conjugate points does not seem to be a mechanism driving Q-disturbances, as the corresponding nighttime behaviour expected between depletions in the summer hemisphere and enhancements in the winter hemisphere is not observed. Pre-storm enhancements occur infrequently, rendering them a poor predictor of geomagnetic disturbances. Pre-storm enhancement morphology does not differ significantly from general quiet time enhancement morphology, suggesting pre-storms are not a special case of Q-disturbances.
- Full Text:
- Date Issued: 2018
- Authors: Orford, Nicola Diane
- Date: 2018
- Subjects: Ionospheric storms , Ionospheric storms -- Africa , Ionosphere , Plasmasphere , Q-disturbances , Total electron content (TEC)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/62672 , vital:28228
- Description: Extreme ionospheric and geomagnetic disturbances affect technology adversely. Prestorm enhancements, considered a potential predictor of geomagnetic storms, occur during quiet conditions prior to geomagnetic disturbances. The ionosphere experiences general disturbances during quiet geomagnetic conditions and these Q- disturbances remain unexplored over Africa. This study used TEC data to characterize the morphology of Q-disturbances over Africa, exploring variations with solar cycle, season, time of occurrence and latitude. Observations from 10 African GPS stations in the equatorial and midlatitude regions show that Q-disturbances in the equatorial region are predominantly driven by E x B variations, while multiple mechanisms affect the midlatitude region. Q- disturbances occur more frequently during nighttime than during daytime and no seasonal trend is observed. Midlatitude Q-disturbance mechanisms are explored in depth, considering substorm activity, the plasmaspheric contribution to GPS TEC and plasma transfer between conjugate points. Substorm activity is not a dominant mechanism, although Q-disturbances occurring under elevated substorm conditions tend to have longer duration and larger amplitude than general Q-disturbances. Many observed Q-disturbances become non-significant once the plasmaspheric contribution to the TEC measurements is removed, indicating that these disturbances occur within the plasmasphere, and not the ionosphere. Transfer of plasma between conjugate points does not seem to be a mechanism driving Q-disturbances, as the corresponding nighttime behaviour expected between depletions in the summer hemisphere and enhancements in the winter hemisphere is not observed. Pre-storm enhancements occur infrequently, rendering them a poor predictor of geomagnetic disturbances. Pre-storm enhancement morphology does not differ significantly from general quiet time enhancement morphology, suggesting pre-storms are not a special case of Q-disturbances.
- Full Text:
- Date Issued: 2018
Beneficiary perceptions regarding farm worker equity share schemes in South Africa
- Authors: Xolo, Siyavuya Nicholas
- Date: 2018
- Subjects: Investments -- South Africa , Investment analysis Land reform -- South Africa Agricultural laborers -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/36323 , vital:33920
- Description: The study aimed to assess beneficiary perceptions regarding farm worker equity share schemes in South Africa. Farm worker equity share schemes started in the early 1990s with the aim of having a special arrangement pertaining to the ownership and operation of a farm between the farmer and the farm workers. This was intended to assist farm workers in not only remaining as farm workers but also to gain ownership of the farm. This could lead to the empowerment of farm workers, better working conditions, improved living standards and their rights to land ownership. Farm worker equity share schemes have been widely reported as having failed to meet their intended objectives, thus, in 2009, the Department of Rural Development and Land Reform initiated a study to assess the implementation of equity share schemes. Although the report was not made public, it reports that out of the 88 equity share schemes at the time, only nine managed to pay dividends ranging from R200 to R2000 per year. As a result, the Department of Rural Development and Land Reform put a moratorium on equity share schemes; this was however removed in 2011. It is against this background that this study was undertaken to assess beneficiaries’ perceptions regarding farm worker equity share schemes in South Africa. A positivistic research paradigm was employed in this study, by means of quantitative research. Secondary data in the form of textbooks, journal articles and Internet sources provided the theoretical framework for this study. Primary data was obtained using the survey method, by means of self-administered structured questionnaires. Convenience and purposive sampling were applied in order to select 20 farms that use equity share schemes. The farms selected for this study were located in the Eastern Cape, Gauteng, Mpumalanga and the Western Cape provinces, covering a variety of farming activities such as citrus fruits, crops, vegetables and wineries. Ideally, a total of 15 farm workers per farm were targeted. However, due to a variation in these farm worker equity share schemes, on some farms less than 15 workers and in others more than 15 workers were selected for the study; this resulted in a total sample size of 341 farm workers. Ten null-hypotheses and a hypothetical model of beneficiary perceptions regarding farm worker equity share schemes were tested. The influence of seven independent variables were tested, these are: stakeholder trust, operational risks, government interventions, two-way communication, farm worker empowerment, training and skills development, and access to resources on farm worker equity share schemes. In addition, the influence of farm worker equity share schemes on three dependent variables, namely, farming performance, sustainability and employee expectations were tested. The Statistica (version 13.2) computer programme was used to analyse the results by means of advanced statistical techniques (such as exploratory factor analysis, regression and correlation analyses) as well as descriptive analysis and frequency distributions. After various statistical procedures, the model was re-specified; some of the variables were then renamed and the hypotheses were adjusted accordingly. The empirical results showed that three key variables to the success of farm worker equity share schemes are stakeholder trust, government interventions and farm owner support. It was determined that these key variables could lead to increased farming performance, farming sustainability and meeting employee expectations. This study provided useful and practical guidelines to farm owners and administrators of equity share schemes, so as to ensure effective strategising that could enhance their competitiveness and long term survival. The findings of this study could inform strategy policy formulation and implementation in the agricultural sector, as pertaining to farm worker equity share schemes. The study used a sound and well-developed research design and methodology, which has been justified and successfully applied to this research; this method can be utilised by other similar studies to conduct empirical research in the field of farm worker equity share schemes. It is envisaged that the results and recommendations of this study could be used to implement effective strategies that could ensure the effective functioning of farm worker equity share schemes in South Africa.
- Full Text:
- Date Issued: 2018
- Authors: Xolo, Siyavuya Nicholas
- Date: 2018
- Subjects: Investments -- South Africa , Investment analysis Land reform -- South Africa Agricultural laborers -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/36323 , vital:33920
- Description: The study aimed to assess beneficiary perceptions regarding farm worker equity share schemes in South Africa. Farm worker equity share schemes started in the early 1990s with the aim of having a special arrangement pertaining to the ownership and operation of a farm between the farmer and the farm workers. This was intended to assist farm workers in not only remaining as farm workers but also to gain ownership of the farm. This could lead to the empowerment of farm workers, better working conditions, improved living standards and their rights to land ownership. Farm worker equity share schemes have been widely reported as having failed to meet their intended objectives, thus, in 2009, the Department of Rural Development and Land Reform initiated a study to assess the implementation of equity share schemes. Although the report was not made public, it reports that out of the 88 equity share schemes at the time, only nine managed to pay dividends ranging from R200 to R2000 per year. As a result, the Department of Rural Development and Land Reform put a moratorium on equity share schemes; this was however removed in 2011. It is against this background that this study was undertaken to assess beneficiaries’ perceptions regarding farm worker equity share schemes in South Africa. A positivistic research paradigm was employed in this study, by means of quantitative research. Secondary data in the form of textbooks, journal articles and Internet sources provided the theoretical framework for this study. Primary data was obtained using the survey method, by means of self-administered structured questionnaires. Convenience and purposive sampling were applied in order to select 20 farms that use equity share schemes. The farms selected for this study were located in the Eastern Cape, Gauteng, Mpumalanga and the Western Cape provinces, covering a variety of farming activities such as citrus fruits, crops, vegetables and wineries. Ideally, a total of 15 farm workers per farm were targeted. However, due to a variation in these farm worker equity share schemes, on some farms less than 15 workers and in others more than 15 workers were selected for the study; this resulted in a total sample size of 341 farm workers. Ten null-hypotheses and a hypothetical model of beneficiary perceptions regarding farm worker equity share schemes were tested. The influence of seven independent variables were tested, these are: stakeholder trust, operational risks, government interventions, two-way communication, farm worker empowerment, training and skills development, and access to resources on farm worker equity share schemes. In addition, the influence of farm worker equity share schemes on three dependent variables, namely, farming performance, sustainability and employee expectations were tested. The Statistica (version 13.2) computer programme was used to analyse the results by means of advanced statistical techniques (such as exploratory factor analysis, regression and correlation analyses) as well as descriptive analysis and frequency distributions. After various statistical procedures, the model was re-specified; some of the variables were then renamed and the hypotheses were adjusted accordingly. The empirical results showed that three key variables to the success of farm worker equity share schemes are stakeholder trust, government interventions and farm owner support. It was determined that these key variables could lead to increased farming performance, farming sustainability and meeting employee expectations. This study provided useful and practical guidelines to farm owners and administrators of equity share schemes, so as to ensure effective strategising that could enhance their competitiveness and long term survival. The findings of this study could inform strategy policy formulation and implementation in the agricultural sector, as pertaining to farm worker equity share schemes. The study used a sound and well-developed research design and methodology, which has been justified and successfully applied to this research; this method can be utilised by other similar studies to conduct empirical research in the field of farm worker equity share schemes. It is envisaged that the results and recommendations of this study could be used to implement effective strategies that could ensure the effective functioning of farm worker equity share schemes in South Africa.
- Full Text:
- Date Issued: 2018
Best simultaneous approximation in normed linear spaces
- Authors: Johnson, Solomon Nathan
- Date: 2018
- Subjects: Normed linear spaces , Approximation theory , Mathematical analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58985 , vital:27400
- Description: In this thesis we consider the problem of simultaneously approximating elements of a set B C X by a single element of a set K C X. This type of a problem arises when the element to be approximated is not known precisely but is known to belong to a set.Thus, best simultaneous approximation is a natural generalization of best approximation which has been studied extensively. The theory of best simultaneous approximation has been studied by many authors, see for example [4], [8], [25], [28], [26] and [12] to name but a few.
- Full Text:
- Date Issued: 2018
- Authors: Johnson, Solomon Nathan
- Date: 2018
- Subjects: Normed linear spaces , Approximation theory , Mathematical analysis
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/58985 , vital:27400
- Description: In this thesis we consider the problem of simultaneously approximating elements of a set B C X by a single element of a set K C X. This type of a problem arises when the element to be approximated is not known precisely but is known to belong to a set.Thus, best simultaneous approximation is a natural generalization of best approximation which has been studied extensively. The theory of best simultaneous approximation has been studied by many authors, see for example [4], [8], [25], [28], [26] and [12] to name but a few.
- Full Text:
- Date Issued: 2018
Between blue and light
- Authors: Campbell, Jennifer
- Date: 2018
- Subjects: South African fiction (English) -- 21st century , Short stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63570 , vital:28441
- Description: My novella follows a narrator observing her life, as she struggles with what it is to live in a world that she finds simultaneously frightening and beautiful. The story touches on the limitations of human connection and with loss in various forms. Set in both Cape Town and small town South Africa, the story explores the inner life of a woman detached and adrift.
- Full Text:
- Date Issued: 2018
- Authors: Campbell, Jennifer
- Date: 2018
- Subjects: South African fiction (English) -- 21st century , Short stories, South African (English) -- 21st century
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: http://hdl.handle.net/10962/63570 , vital:28441
- Description: My novella follows a narrator observing her life, as she struggles with what it is to live in a world that she finds simultaneously frightening and beautiful. The story touches on the limitations of human connection and with loss in various forms. Set in both Cape Town and small town South Africa, the story explores the inner life of a woman detached and adrift.
- Full Text:
- Date Issued: 2018
Biochemical characterisation and small molecule modulation of the interaction between two cytosolic Hsp70s from Trypanosoma brucei and potential co-chaperones
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
- Authors: Bentley, Stephen John
- Date: 2018
- Subjects: Uncatalogued
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/63402 , vital:28407
- Description: Expected release date-April 2019
- Full Text:
- Date Issued: 2018
Bioinformatics tool development with a focus on structural bioinformatics and the analysis of genetic variation in humans
- Authors: Brown, David K
- Date: 2018
- Subjects: Bioinformatics , Human genetics -- Variation , High performance computing , Workflow management systems , Molecular dynamics , Next generation sequencing , Human Mutation Analysis (HUMA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60708 , vital:27820
- Description: This thesis is divided into three parts, united under the general theme of bioinformatics tool development and variation analysis. Part 1 describes the design and development of the Job Management System (JMS), a workflow management system for high performance computing (HPC). HPC has become an integral part of bioinformatics. Computational methods for molecular dynamics and next generation sequencing (NGS) analysis, which require complex calculations on large datasets, are not yet feasible on desktop computers. As such, powerful computer clusters have been employed to perform these calculations. However, making use of these HPC clusters requires familiarity with command line interfaces. This excludes a large number of researchers from taking advantage of these resources. JMS was developed as a tool to make it easier for researchers without a computer science background to make use of HPC. Additionally, JMS can be used to host computational tools and pipelines and generates both web-based interfaces and RESTful APIs for those tools. The web-based interfaces can be used to quickly and easily submit jobs to the underlying cluster. The RESTful web API, on the other hand, allows JMS to provided backend functionality for external tools and web servers that want to run jobs on the cluster. Numerous tools and workflows have already been added to JMS, several of which have been incorporated into external web servers. One such web server is the Human Mutation Analysis (HUMA) web server and database. HUMA, the topic of part 2 of this thesis, is a platform for the analysis of genetic variation in humans. HUMA aggregates data from various existing databases into a single, connected and related database. The advantages of this are realized in the powerful querying abilities that it provides. HUMA includes protein, gene, disease, and variation data and can be searched from the angle of any one of these categories. For example, searching for a protein will return the protein data (e.g. protein sequences, structures, domains and families, and other meta-data). However, the related nature of the database means that genes, diseases, variation, and literature related to the protein will also be returned, giving users a powerful and holistic view of all data associated with the protein. HUMA also provides links to the original sources of the data, allowing users to follow the links to find additional details. HUMA aims to be a platform for the analysis of genetic variation. As such, it also provides tools to visualize and analyse the data (several of which run on the underlying cluster, via JMS). These tools include alignment and 3D structure visualization, homology modeling, variant analysis, and the ability to upload custom variation datasets and map them to proteins, genes and diseases. HUMA also provides collaboration features, allowing users to share and discuss datasets and job results. Finally, part 3 of this thesis focused on the development of a suite of tools, MD-TASK, to analyse genetic variation at the protein structure level via network analysis of molecular dynamics simulations. The use of MD-TASK in combination with the tools developed in the previous parts of this thesis is showcased via the analysis of variation in the renin-angiotensinogen complex, a vital part of the renin-angiotensin system.
- Full Text:
- Date Issued: 2018
- Authors: Brown, David K
- Date: 2018
- Subjects: Bioinformatics , Human genetics -- Variation , High performance computing , Workflow management systems , Molecular dynamics , Next generation sequencing , Human Mutation Analysis (HUMA)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/60708 , vital:27820
- Description: This thesis is divided into three parts, united under the general theme of bioinformatics tool development and variation analysis. Part 1 describes the design and development of the Job Management System (JMS), a workflow management system for high performance computing (HPC). HPC has become an integral part of bioinformatics. Computational methods for molecular dynamics and next generation sequencing (NGS) analysis, which require complex calculations on large datasets, are not yet feasible on desktop computers. As such, powerful computer clusters have been employed to perform these calculations. However, making use of these HPC clusters requires familiarity with command line interfaces. This excludes a large number of researchers from taking advantage of these resources. JMS was developed as a tool to make it easier for researchers without a computer science background to make use of HPC. Additionally, JMS can be used to host computational tools and pipelines and generates both web-based interfaces and RESTful APIs for those tools. The web-based interfaces can be used to quickly and easily submit jobs to the underlying cluster. The RESTful web API, on the other hand, allows JMS to provided backend functionality for external tools and web servers that want to run jobs on the cluster. Numerous tools and workflows have already been added to JMS, several of which have been incorporated into external web servers. One such web server is the Human Mutation Analysis (HUMA) web server and database. HUMA, the topic of part 2 of this thesis, is a platform for the analysis of genetic variation in humans. HUMA aggregates data from various existing databases into a single, connected and related database. The advantages of this are realized in the powerful querying abilities that it provides. HUMA includes protein, gene, disease, and variation data and can be searched from the angle of any one of these categories. For example, searching for a protein will return the protein data (e.g. protein sequences, structures, domains and families, and other meta-data). However, the related nature of the database means that genes, diseases, variation, and literature related to the protein will also be returned, giving users a powerful and holistic view of all data associated with the protein. HUMA also provides links to the original sources of the data, allowing users to follow the links to find additional details. HUMA aims to be a platform for the analysis of genetic variation. As such, it also provides tools to visualize and analyse the data (several of which run on the underlying cluster, via JMS). These tools include alignment and 3D structure visualization, homology modeling, variant analysis, and the ability to upload custom variation datasets and map them to proteins, genes and diseases. HUMA also provides collaboration features, allowing users to share and discuss datasets and job results. Finally, part 3 of this thesis focused on the development of a suite of tools, MD-TASK, to analyse genetic variation at the protein structure level via network analysis of molecular dynamics simulations. The use of MD-TASK in combination with the tools developed in the previous parts of this thesis is showcased via the analysis of variation in the renin-angiotensinogen complex, a vital part of the renin-angiotensin system.
- Full Text:
- Date Issued: 2018
Biological activities of tulbaghia violacea against cryptococcus species
- Authors: Mitradev, Pattoo
- Date: 2018
- Subjects: Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Medicinal plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32772 , vital:32357
- Description: Cryptococcus neoformans and Cryptococcus gattii, which are environmental yeasts, are the etiological agents of cryptococcosis in both immunocompromised and immunocompetent individuals, and account for high mortality and morbidity rates in sub-Saharan Africa. The current antifungal agents used for treatment of cryptococcal infections either target the fungal cell wall (β-(1,3) glucan and chitin) or cell membrane directly or ergosterol biosynthetic pathways or fungal DNA and RNA. Gaps in antifungal therapy include the unavailability and exhorbitant costs of these drugs especially to patients in the developing world. Drug resistance to conventional drugs is also an ever-increasing problem. It is therefore essential to find alternative natural compounds from medicinal plants that are safer, cheaper and more widely available. Tulbaghia violacea, also known as wild garlic, has been used as a traditional remedy in South Africa for the treatment of several ailments. Aqueous and organic extracts of the plant have been demonstrated to have antimicrobial and antifungal activity against several pathogens. However, there is a huge gap in our current knowledge in that the mechanism/s of action/s of these extracts have not been fully investigated. The focus of the current study therefore was to determine whether T. violacea extracts from the roots, rhizome, leaves and tubers exhibited antifungal activity against C. neoformans and C. gattii and to evaluate the ability of the rhizome extract to induce changes in key fungal virulence factors. Three mechanisms (ergosterol, β-(1,3) glucan and chitin production) regulating the antifungal activity of the rhizome extract were also examined. In the current study, phytochemical analysis of aqueous extracts of the roots, leaves, rhizomes and tubers showed that the rhizomes had the highest phenolic, saponin and tannin content when compared to the other plant organs. Fingerprinting by GC-MS revealed identical compounds in the different plant parts with the detection of 4 H Pyran-4-one DDMP (known antifungal), previously unreported in studies on T. violacea. The bulk of the extract comprised of 40% sulphur-containing and 20% furan-containing compounds. The remaining minor compounds comprised of 2x alcohols (13.3%), 1x pyran (6.7%), 1x ketone (6.7%), 1x halogen (6.7%) and 1x acid (6.7%) compounds. The rhizomes also had highest content of 2 methyl methioacetic acid, benzophenone and chloromethyl methylsulfide compared to the other plant parts. The rhizomes were found to be more potent against both pathogenic fungi tested here with an MIC and MFC of 1.25 mg/ml. Nystatin was included as a positive control when determining the MIC’s and MFC’s of the different plant extracts. The antifungal nature of the T. violacea extracts in the current study may be due to the synergistic effects of the sulphide, furan, pyran and ketone compounds present in the extracts, but this still remains to be verified in future studies. An investigation of the effects of an aqueous rhizome extract of T. violacea on Cryptococcus virulence factors showed that phospholipase activity of C. neoformans and C. gattii remained unaffected with increasing sub-lethal doses of the plant extract. There was significant reduction in urease production in both fungi in a dose dependent manner relative to the untreated cultures after 24 hr exposure to the extract. However, urease production reverted to normal after 48 hr post exposure implying that the cultures were able to recover due to temporary inhibition of urease activity. A significant decrease in melanin production was observed in both C. neoformans and C. gattii with increasing sub-inhibitory concentrations of the rhizome extract. Investigation of the effect of the plant extract on the ultrastucture of the fungi via Transmission Electron Microscopy showed the induction of cytomorphological changes in C. neoformans and C. gattii. Changes included thickening of the cell wall, an increase in the number of vacuoles, mitochondrial swelling and occasional detachment of the membrane from the cell wall. These changes suggest the activation of possible defence mechanisms to compensate for the loss of cellular materials or an effort to sequester toxic T. violacea components or toxic intermediates generated from inhibited cellular pathways. The capsule size and architecture remained unaltered in the presence of sub-lethal doses of the rhizome extract. To study the mechanism of action of the rhizome extract on ergosterol biosynthesis, total sterols were extracted and ergosterol, squalene, 2,3-oxidosqualene and lanosterol were quantified using Reverse Phase High Performance Liquid Chromatography. Ergosterol concentration declined in a dose dependent manner for both pathogenic yeasts similar to the positive control terbinafine, while there was a slight accumulation of squalene in C. gattii only. 2,3-oxidosqualene levels accumulated in both fungi relative to the untreated control. Lanosterol production showed an oscillatory trend for the two microorganisms. Together, these findings indicate that the rhizome extract is capable of inhibiting squalene epoxidase and 2,3-oxidosqualene/ lanosterol cyclase causing a decrease in ergosterol production.
- Full Text:
- Date Issued: 2018
- Authors: Mitradev, Pattoo
- Date: 2018
- Subjects: Violaceae -- Therapeutic use -- South Africa , Anticoagulants (Medicine) , Medicinal plants -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/32772 , vital:32357
- Description: Cryptococcus neoformans and Cryptococcus gattii, which are environmental yeasts, are the etiological agents of cryptococcosis in both immunocompromised and immunocompetent individuals, and account for high mortality and morbidity rates in sub-Saharan Africa. The current antifungal agents used for treatment of cryptococcal infections either target the fungal cell wall (β-(1,3) glucan and chitin) or cell membrane directly or ergosterol biosynthetic pathways or fungal DNA and RNA. Gaps in antifungal therapy include the unavailability and exhorbitant costs of these drugs especially to patients in the developing world. Drug resistance to conventional drugs is also an ever-increasing problem. It is therefore essential to find alternative natural compounds from medicinal plants that are safer, cheaper and more widely available. Tulbaghia violacea, also known as wild garlic, has been used as a traditional remedy in South Africa for the treatment of several ailments. Aqueous and organic extracts of the plant have been demonstrated to have antimicrobial and antifungal activity against several pathogens. However, there is a huge gap in our current knowledge in that the mechanism/s of action/s of these extracts have not been fully investigated. The focus of the current study therefore was to determine whether T. violacea extracts from the roots, rhizome, leaves and tubers exhibited antifungal activity against C. neoformans and C. gattii and to evaluate the ability of the rhizome extract to induce changes in key fungal virulence factors. Three mechanisms (ergosterol, β-(1,3) glucan and chitin production) regulating the antifungal activity of the rhizome extract were also examined. In the current study, phytochemical analysis of aqueous extracts of the roots, leaves, rhizomes and tubers showed that the rhizomes had the highest phenolic, saponin and tannin content when compared to the other plant organs. Fingerprinting by GC-MS revealed identical compounds in the different plant parts with the detection of 4 H Pyran-4-one DDMP (known antifungal), previously unreported in studies on T. violacea. The bulk of the extract comprised of 40% sulphur-containing and 20% furan-containing compounds. The remaining minor compounds comprised of 2x alcohols (13.3%), 1x pyran (6.7%), 1x ketone (6.7%), 1x halogen (6.7%) and 1x acid (6.7%) compounds. The rhizomes also had highest content of 2 methyl methioacetic acid, benzophenone and chloromethyl methylsulfide compared to the other plant parts. The rhizomes were found to be more potent against both pathogenic fungi tested here with an MIC and MFC of 1.25 mg/ml. Nystatin was included as a positive control when determining the MIC’s and MFC’s of the different plant extracts. The antifungal nature of the T. violacea extracts in the current study may be due to the synergistic effects of the sulphide, furan, pyran and ketone compounds present in the extracts, but this still remains to be verified in future studies. An investigation of the effects of an aqueous rhizome extract of T. violacea on Cryptococcus virulence factors showed that phospholipase activity of C. neoformans and C. gattii remained unaffected with increasing sub-lethal doses of the plant extract. There was significant reduction in urease production in both fungi in a dose dependent manner relative to the untreated cultures after 24 hr exposure to the extract. However, urease production reverted to normal after 48 hr post exposure implying that the cultures were able to recover due to temporary inhibition of urease activity. A significant decrease in melanin production was observed in both C. neoformans and C. gattii with increasing sub-inhibitory concentrations of the rhizome extract. Investigation of the effect of the plant extract on the ultrastucture of the fungi via Transmission Electron Microscopy showed the induction of cytomorphological changes in C. neoformans and C. gattii. Changes included thickening of the cell wall, an increase in the number of vacuoles, mitochondrial swelling and occasional detachment of the membrane from the cell wall. These changes suggest the activation of possible defence mechanisms to compensate for the loss of cellular materials or an effort to sequester toxic T. violacea components or toxic intermediates generated from inhibited cellular pathways. The capsule size and architecture remained unaltered in the presence of sub-lethal doses of the rhizome extract. To study the mechanism of action of the rhizome extract on ergosterol biosynthesis, total sterols were extracted and ergosterol, squalene, 2,3-oxidosqualene and lanosterol were quantified using Reverse Phase High Performance Liquid Chromatography. Ergosterol concentration declined in a dose dependent manner for both pathogenic yeasts similar to the positive control terbinafine, while there was a slight accumulation of squalene in C. gattii only. 2,3-oxidosqualene levels accumulated in both fungi relative to the untreated control. Lanosterol production showed an oscillatory trend for the two microorganisms. Together, these findings indicate that the rhizome extract is capable of inhibiting squalene epoxidase and 2,3-oxidosqualene/ lanosterol cyclase causing a decrease in ergosterol production.
- Full Text:
- Date Issued: 2018