A chemo-enzymatic process for the production of beta-thymidine, a key intermediate in antiretrovirol manufacture
- Gordon, Gregory Ernest Robert
- Authors: Gordon, Gregory Ernest Robert
- Date: 2010
- Subjects: HIV infections -- Treatment -- South Africa , HIV infections -- South Africa -- Prevention , Antiretroviral agents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10423 , http://hdl.handle.net/10948/d1016217
- Description: The socio-economic impact of HIV/AIDS on South Africa has resulted in lower gross domestic product, loss of skills in key sectors such as education, and increased health-care costs in providing access to treatment. Currently active pharmaceutical ingredients (API’s) such as stavudine (d4T) and azidothymidine (AZT) are imported from India and China, while formulation is conducted locally. A strategy was initiated between CSIR Biosciences and LIFElab under the auspices of Arvir Technologies to investigate the feasibility of local antiretroviral manufacture (d4T and AZT) or the manufacture of a key intermediate such as β- thymidine (dT). Several advantages associated with successful implementation of this strategy include ensuring a local supply of API’s, thus reducing reliance on procurement from foreign sources and reducing the effect of foreign exchange rate fluctuations on providing cost effective access to treatment. A local supply source would also reduce the imports and thus aid the balance of payments deficit, and in addition to this, provide stimulus in the local pharmaceutical manufacturing industry (which has been in decline for several decades), resulting in increased skills and employment opportunities. This thesis describes the development of a superior chemo-enzymatic process for the production of β-thymidine (72 percent yield, prior to isolation), a key intermediate in the preparation of anti-retrovirals. Alternative processes based purely on chemical or bioprocess transformations to prepare either 5-methyluridine (5-MU) or dT suffer from several disadvantages: lengthy transformations due to protection/deprotection strategies, low selectivties and product yields (30 percent in the chemical process) and isolation of the product from dilute process streams requiring the use of large uneconomical reactors (bioprocesss). This contributes significantly to the cost of d4T and AZT manufacture. Our novel chemoenzymatic process comprises of a biocatalytic reaction for the production of 5-MU, with subsequent chemical transformation into dT (3 steps) negating and circumventing the limitations of the chemical or bioprocess routes. During the course of this project development, the β-thymidine selling price declined from 175 $/kg (2005) to 100 $/kg (2008). However, the process described in this work is still competitive based on the current β- thymidine selling price of 100 $/kg. The process economics show that with further optimization and increasing the isolated dT yield from 70 percent to 90 percent, the variable cost decreases from 136 $/kg to 110 $/kg. The increase in isolated yield is highly probable, based on solubility data of β-thymidine. The decrease in β-thymidine selling price and technological improvement in dT manufacture should translate into lower API manufacture costs and more cost effective access to treatment. Our novel biocatalytic process producing 5-MU uses a coupled enzyme system employing PNP, Purine Nucleoside Phosphorylase and PyNP, Pyrimidine Nucleoside Phosphorylase. The overall transglycosylation reaction may be decoupled into the phosphorolysis reaction (PNP) and synthesis reaction (PyNP). During the phosphorolysis reaction, guanosine is converted into guanine and ribose-1-phosphate (R-1-P) in the presence of PNP enzyme. The reaction intermediate R-1-P is then coupled to thymine in the presence of PyNP enzyme during the synthesis reaction, producing 5-MU. The process was scaled up from lab-scale to bench-scale (10 - 20 L) and demonstrated to be robust and reproducible. This is evident from the average guanosine conversion (94.7 percent ± 2.03) and 5-MU yield (88.2 percent ± 6.21) and mole balance (104 percent ± 7.61) which were obtained at bench-scale (3 replicates, 10 L). The reaction was carried out at reactor productivities of between 7 – 11 g.L-1.h-1. The integration of the biocatalytic process and chemical processes was successfully carried out, showing that 5-MU produced using our novel biocatalytic process behaved similarly to commercially available 5- MU (ex. Dayang Chemicals, China). A PCT patent application (Ref. No. P44422PC01) on this chemo-enzymatic process has been filed and currently public private partnerships are being explored through Arvir Technologies to evaluate and validate this technology at one ton scale.
- Full Text:
- Date Issued: 2010
- Authors: Gordon, Gregory Ernest Robert
- Date: 2010
- Subjects: HIV infections -- Treatment -- South Africa , HIV infections -- South Africa -- Prevention , Antiretroviral agents
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10423 , http://hdl.handle.net/10948/d1016217
- Description: The socio-economic impact of HIV/AIDS on South Africa has resulted in lower gross domestic product, loss of skills in key sectors such as education, and increased health-care costs in providing access to treatment. Currently active pharmaceutical ingredients (API’s) such as stavudine (d4T) and azidothymidine (AZT) are imported from India and China, while formulation is conducted locally. A strategy was initiated between CSIR Biosciences and LIFElab under the auspices of Arvir Technologies to investigate the feasibility of local antiretroviral manufacture (d4T and AZT) or the manufacture of a key intermediate such as β- thymidine (dT). Several advantages associated with successful implementation of this strategy include ensuring a local supply of API’s, thus reducing reliance on procurement from foreign sources and reducing the effect of foreign exchange rate fluctuations on providing cost effective access to treatment. A local supply source would also reduce the imports and thus aid the balance of payments deficit, and in addition to this, provide stimulus in the local pharmaceutical manufacturing industry (which has been in decline for several decades), resulting in increased skills and employment opportunities. This thesis describes the development of a superior chemo-enzymatic process for the production of β-thymidine (72 percent yield, prior to isolation), a key intermediate in the preparation of anti-retrovirals. Alternative processes based purely on chemical or bioprocess transformations to prepare either 5-methyluridine (5-MU) or dT suffer from several disadvantages: lengthy transformations due to protection/deprotection strategies, low selectivties and product yields (30 percent in the chemical process) and isolation of the product from dilute process streams requiring the use of large uneconomical reactors (bioprocesss). This contributes significantly to the cost of d4T and AZT manufacture. Our novel chemoenzymatic process comprises of a biocatalytic reaction for the production of 5-MU, with subsequent chemical transformation into dT (3 steps) negating and circumventing the limitations of the chemical or bioprocess routes. During the course of this project development, the β-thymidine selling price declined from 175 $/kg (2005) to 100 $/kg (2008). However, the process described in this work is still competitive based on the current β- thymidine selling price of 100 $/kg. The process economics show that with further optimization and increasing the isolated dT yield from 70 percent to 90 percent, the variable cost decreases from 136 $/kg to 110 $/kg. The increase in isolated yield is highly probable, based on solubility data of β-thymidine. The decrease in β-thymidine selling price and technological improvement in dT manufacture should translate into lower API manufacture costs and more cost effective access to treatment. Our novel biocatalytic process producing 5-MU uses a coupled enzyme system employing PNP, Purine Nucleoside Phosphorylase and PyNP, Pyrimidine Nucleoside Phosphorylase. The overall transglycosylation reaction may be decoupled into the phosphorolysis reaction (PNP) and synthesis reaction (PyNP). During the phosphorolysis reaction, guanosine is converted into guanine and ribose-1-phosphate (R-1-P) in the presence of PNP enzyme. The reaction intermediate R-1-P is then coupled to thymine in the presence of PyNP enzyme during the synthesis reaction, producing 5-MU. The process was scaled up from lab-scale to bench-scale (10 - 20 L) and demonstrated to be robust and reproducible. This is evident from the average guanosine conversion (94.7 percent ± 2.03) and 5-MU yield (88.2 percent ± 6.21) and mole balance (104 percent ± 7.61) which were obtained at bench-scale (3 replicates, 10 L). The reaction was carried out at reactor productivities of between 7 – 11 g.L-1.h-1. The integration of the biocatalytic process and chemical processes was successfully carried out, showing that 5-MU produced using our novel biocatalytic process behaved similarly to commercially available 5- MU (ex. Dayang Chemicals, China). A PCT patent application (Ref. No. P44422PC01) on this chemo-enzymatic process has been filed and currently public private partnerships are being explored through Arvir Technologies to evaluate and validate this technology at one ton scale.
- Full Text:
- Date Issued: 2010
A chronic care coordination model for HIV-positive children requiring antiretroviral therapy
- Authors: Williams, Margaret
- Date: 2013
- Subjects: HIV-positive children -- Care -- South Africa , HIV-positive persons -- Care -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10062 , http://hdl.handle.net/10948/d1020346
- Description: The human immunodeficiency virus / acquired immune deficiency syndrome pandemic (HIV/AIDS) continues to increase in prevalence worldwide, particularly in South Africa. There is a concurrent and distinct increase in the prevalence of HIV/AIDS and HIV-related diseases in the paediatric population in South Africa, particularly those using public sector health services, with a corresponding increase in morbidity and mortality rates (Abdool Karim & Abdool Karim, 2010:363), which impacts greatly on paediatric healthcare services. Adding to this, the provision of paediatric antiretroviral care has numerous stumbling blocks, not least of which is lack of decentralisation of facilities to provide treatment. There is the additional shortage of staff, which includes staff that are comfortable dealing with children, lack of training programmes on the provision of antiretroviral therapy to children, and minimal on-site mentorship of staff regarding HIV/AIDS disease in children. This lack of capacity in the healthcare system means that not all of those who require treatment will be able to access it, and this is particularly pertinent to paediatric patients (Meyers et al., 2007:198). Therefore the purpose of this research was to develop a nursing model that would assist healthcare professionals, in particular professional nurses, to optimise the comprehensive treatment, care and support for HIV-positive children who require antiretroviral therapy at PHC clinics. To achieve the purpose of this study, a theory-generating design based on a qualitative, explorative, descriptive and contextual approach was implemented by the researcher to gain an understanding of how the healthcare professionals and parents/caregivers of HIV-positive children experienced the comprehensive treatment, care and support provided at primary healthcare clinics. The information obtained was used to develop a chronic care coordination model for the optimisation of comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy. The study design comprised the following four steps: Step One of the research design focused on the identification, classification and definition of the major concepts of the study. This involved describing and selecting the research population and the sampling process prior to conducting the field work which comprised in-depth interviews with two groups of participants, namely healthcare professionals and parents/caregivers who accompany their HIV-positive children to PHC clinics in order to receive antiretroviral therapy. Step Two of the research design focused on the development of relationship statements in order to bring clarity and direction to the understanding of the phenomenon of interest. Step Three of the design concentrated on the development and description of the chronic care coordination model for optimising comprehensive treatment, care and support for HIV-positive children who require antiretroviral therapy in order to ensure a well-managed child on ART. A visual representation of the structure of the model for chronic care coordination was given and described as well as a detailed description of the process of the model. Step Four was the last step of the research design and its focus was the development of guidelines for the operationalisation of the model for chronic care coordination for the optimisation of comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy at PHC clinics. Guidelines and operational implications for each of the five sequential steps of the model were developed. The evaluation criteria of Chinn & Kramer (2008:237‒248) were used to evaluate the model. It is therefore concluded that the researcher succeeded in achieving the purpose for this study because a chronic care coordination model that is understandable, clear, simple, applicable and significant to nursing practice has been developed for use by healthcare professionals, particularly professional nurses, in order to optimise the comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy at primary healthcare clinics.
- Full Text:
- Date Issued: 2013
- Authors: Williams, Margaret
- Date: 2013
- Subjects: HIV-positive children -- Care -- South Africa , HIV-positive persons -- Care -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10062 , http://hdl.handle.net/10948/d1020346
- Description: The human immunodeficiency virus / acquired immune deficiency syndrome pandemic (HIV/AIDS) continues to increase in prevalence worldwide, particularly in South Africa. There is a concurrent and distinct increase in the prevalence of HIV/AIDS and HIV-related diseases in the paediatric population in South Africa, particularly those using public sector health services, with a corresponding increase in morbidity and mortality rates (Abdool Karim & Abdool Karim, 2010:363), which impacts greatly on paediatric healthcare services. Adding to this, the provision of paediatric antiretroviral care has numerous stumbling blocks, not least of which is lack of decentralisation of facilities to provide treatment. There is the additional shortage of staff, which includes staff that are comfortable dealing with children, lack of training programmes on the provision of antiretroviral therapy to children, and minimal on-site mentorship of staff regarding HIV/AIDS disease in children. This lack of capacity in the healthcare system means that not all of those who require treatment will be able to access it, and this is particularly pertinent to paediatric patients (Meyers et al., 2007:198). Therefore the purpose of this research was to develop a nursing model that would assist healthcare professionals, in particular professional nurses, to optimise the comprehensive treatment, care and support for HIV-positive children who require antiretroviral therapy at PHC clinics. To achieve the purpose of this study, a theory-generating design based on a qualitative, explorative, descriptive and contextual approach was implemented by the researcher to gain an understanding of how the healthcare professionals and parents/caregivers of HIV-positive children experienced the comprehensive treatment, care and support provided at primary healthcare clinics. The information obtained was used to develop a chronic care coordination model for the optimisation of comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy. The study design comprised the following four steps: Step One of the research design focused on the identification, classification and definition of the major concepts of the study. This involved describing and selecting the research population and the sampling process prior to conducting the field work which comprised in-depth interviews with two groups of participants, namely healthcare professionals and parents/caregivers who accompany their HIV-positive children to PHC clinics in order to receive antiretroviral therapy. Step Two of the research design focused on the development of relationship statements in order to bring clarity and direction to the understanding of the phenomenon of interest. Step Three of the design concentrated on the development and description of the chronic care coordination model for optimising comprehensive treatment, care and support for HIV-positive children who require antiretroviral therapy in order to ensure a well-managed child on ART. A visual representation of the structure of the model for chronic care coordination was given and described as well as a detailed description of the process of the model. Step Four was the last step of the research design and its focus was the development of guidelines for the operationalisation of the model for chronic care coordination for the optimisation of comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy at PHC clinics. Guidelines and operational implications for each of the five sequential steps of the model were developed. The evaluation criteria of Chinn & Kramer (2008:237‒248) were used to evaluate the model. It is therefore concluded that the researcher succeeded in achieving the purpose for this study because a chronic care coordination model that is understandable, clear, simple, applicable and significant to nursing practice has been developed for use by healthcare professionals, particularly professional nurses, in order to optimise the comprehensive treatment, care and support for HIV-positive children requiring antiretroviral therapy at primary healthcare clinics.
- Full Text:
- Date Issued: 2013
A classification of large wetlands in Africa’s elevated drylands based on their formation, structure, and hydrological functioning using Earth Observation (EO) data and Geographic Information System (GIS)
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
- Date Issued: 2020
- Authors: Lidzhegu, Zwidofhelangani
- Date: 2020
- Subjects: Wetlands -- Africa -- Classification , Wetlands -- Africa -- Research , Wetlands -- Africa -- Monitoring , Topographical surveying -- Africa , Hydrological surveys == Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142668 , vital:38100
- Description: Due to wetland inaccessibility and limited wetland geomorphological studies, there is limited information on the geomorphological origin and hydrological functioning of different types of wetlands in Africa’s elevated drylands. As a result, there is limited information for the development of a comprehensive wetland classification system that classifies wetlands based on long-term geomorphic processes that determine their formation and shape, their structure and hydrological functioning. Therefore, the current study was designed to classify large wetlands in Africa’s elevated drylands based on processes that determine their formation, and shape their structure and hydrological functioning using remote sensing and Geographic Information System (GIS) techniques. Although wetlands perform a number of hydrological functions including groundwater recharge and water purification, the current study focuses mainly on their flood attenuation function. Detailed analysis of topographic information was undertaken using Shuttle Radar Topographic Mission (SRTM) elevations measured at the scale of 30 m x 30 m. LandsatLook and Google Earth images, tectonic as well as geological data were used as supplementary data for developing an understanding of the origin, structure and hydrological characteristics of wetlands. The Principal Component Analysis (PCA) of wetland environmental variables was used to identify and explain wetland heterogeneity. The results of the study showed that fluvial processes, tectonic history and the evolution of Africa’s landscape played a fundamental role in the formation and evolution of wetlands. This study demonstrates a wide range of processes that contribute to wetland formation, structure and functioning. At one extreme it is clear that tectonic processes may be primarily responsible for the creation of basins that host wetlands. At another extreme, wetlands may be structured primarily by fluvial processes. At a third extreme are wetlands that superficially appear to be structured by fluvial processes, but which have their structures modified by gradual rising of the base level at their distal ends, either through marginal uplift adjacent to rift valleys, or through aggradation of a floodplain that blocks a tributary valley. Overall, the classification of wetlands considered in this study can be summarised into four distinct groupings, with two of these divided further into two groupings each: (1) Tectonic basins with little or no indication of fluvial development (Bahi and Wembere wetlands), (2) Tectonic basins evolving towards a wetland with a structure increasingly shaped by fluvial characteristics (Usangu wetland), (3) Fluvially modified valleys with a local base level at the toe of the wetland such as a resistant lithology or a tectonic control that limits the rate of incision of easily weathered and eroded lithologies, leading to valley widening and longitudinal slope reduction, which are of two distinct types: (a) With a catchment on Kalahari Group sediment that is transported fluvially as bedload, and therefore with no prominent alluvial ridge or backwater depressions (Upper Zambezi and Barotse wetlands), (b) With a catchment that produces abundant fine sediment that is deposited as overbank sediments, leading to channel migration via meandering and to the construction of an elevated alluvial ridge (Lufira wetland), (4) Fluvially modified basins with evidence of gradual elevation of the base level at the toe of the wetland, which are of two types: (a) Tectonic marginal rift valley uplift such that they behave more as depression wetlands rather than as wetlands shaped by fluvial processes (Kafue and Luapula wetlands), (b) Tributary valley wetlands blocked by aggradation of the trunk valley (Lukanga wetland). In conclusion, although few geomorphological studies have been conducted on southern African wetlands because of their inaccessibility, Africa’s surface topography and its historical evolution, as well as aridity, provide an opportunity for illustrating the important role that the long-term tectonic, geological and geomorphological processes play in determining wetland origin, structure and dynamics. GIS methodology and Earth Observation (EO) data on the other hand, provide a practical means for acquiring information on inaccessible and hard to traverse wetland systems. A novel cut-and-fill approach for delineating wetlands from a Digital Elevation Model (DEM) was presented as another way in which GIS methodology and Earth Observation (EO) data can provide practical means for assessing inaccessible and hard to traverse wetland systems.
- Full Text:
- Date Issued: 2020
A co-constructed practice model for supporting parents of children in conflict with the law
- Authors: Abdulla, Zurina
- Date: 2019
- Subjects: Children's rights -- South Africa , Children -- Legal status, laws, etc --South Africa , Parent and child -- Research -- South Africa , Social work with youth -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30474 , vital:30949
- Description: The unique historical stressors linked to South Africa’s apartheid legacy, continues to manifest in the form of economic exclusion, social exclusion, inequality and poverty, with parents being subjugated to service users and extenders rather than included as service advocates, particularly in the child justice system. Furthermore, policies and practices do not include, engage and support parents on an intra and interpersonal level. Parents of children in conflict with the law, experience their children’s charge or arrest as well as their subsequent journey through the child justice system as a crisis resulting in their need for emotional, informational, practical and professional support during the child justice process. The similarities and differences between the contexts of child protection and child justice in supporting parents illuminates the existing gaps in child justice legislation, policy and practice resulting in a lack of support for parents during the child justice process. In the Children’s Act 38 of 2005, it is recognised that parents have a legal responsibility towards their children and that in fulfilling this responsibility parents can access support services to assist them when they face challenges in fulfilling this responsibility. In contrast, despite 80 percent of children in conflict with the law being released into parental care and parents expressing the need for support in fulfilling their parental responsibility, in this regard the Child Justice Act 75 of 2008 fails to make provision for parents to access support services. The child justice system’s narrow focus on parents as service extenders contributes to parents’ being excluded from targeted support services resulting in parents’ support needs not being addressed. The lack of programmes and services aimed at supporting parents highlight the need for coordinated services that address the multiple stressors parents are exposed to. To this end, this study was aimed at coconstructing a practice model for supporting parents of children in conflict with the law. The theoretical lenses employed in the current study namely; the Ecological systems model and the Buffering effect model describes the various systems parents need support from and the type of support they need from their family, community and professionals. Guided by a qualitative approach, the present study integrated applied research, in particular intervention design and development with participatory action research as it allowed systematic collaboration during the research process to ensure rigour. This study involved participants from two research sites namely, the Nerina One- Stop Child Justice Centre in Port Elizabeth and the Reception, Assessment and Referral office at the Uitenhage magistrates’ court. Employing a non-probability purposive sampling method, this study facilitated the participation of parents of children in conflict with the law and child justice officials who met the inclusion criteria, in the co-design and development of a practice model for supporting parents of children in conflict with the law. Participants assumed an expert and collaborative role, which enabled the co-construction of knowledge, meaning and innovation of the practice model. Qualitative data collection methods namely, twelve focus groups and thirty two participant observations, were used to explore, co-construct, describe and design a practice model for supporting parents of children in conflict with the law during the child justice process. Thematic analyses was employed to condense the data, search for codes, categories, themes, relationships and patterns in the data. Due to the research approach and design, data analysis was ongoing and informed design and development of the practice model. Based on the thematic analysis and synthesis both descriptive and analytic themes emerged. To ensure trustworthiness, this study employed various strategies to strengthen commitment, rigour, transparency and coherence. In addition, the participative research process, the inclusion of multiple forms of qualitative inquiry and the significance of the study contributed to the validity and quality of the study. Ethical considerations applicable to the study included participants’ voluntary participation, their informed consent and ensuring participants’ privacy or maintaining confidentially. Various strategies were employed to prevent or minimise risk to participants. The findings showed that formal sources of support, in particular, offer opportunities for parents to access individual and family counselling, parenting advice, and peer support. The study also highlighted the importance of recognising parents as a subsystem in the child justice system offers potential opportunities for inclusion of parents as co-facilitators of parenting programmes or support groups, as peer supporters during the child justice process. Parents’ inclusion as a partner in the child justice system is highlighted as an opportunity for parents to be able to vi participate in child justice fora, oversight committees and accreditation committees to influence policy, services and budget allocations for services to support parents of children in conflict with the law. This study’s contribution to the existing body of knowledge is an integrated, multidisciplinary, multi-phase co-constructed practice model that would enable inclusion of, and support for, parents of children in conflict with the law prior to, during and after the child justice. The co-constructed practice model (a) involves a continuum of parent-centred support for and inclusion of parents prior to, during and after the child justice process; (b) advances an inclusive and collaborative child justice system that views parents as important stakeholders in determining the type of services they need and being involved in developing practice; and (c) promotes parents as equal partners in decision making and policy making to influence legislation, policy and practice in the child justice system.
- Full Text:
- Date Issued: 2019
- Authors: Abdulla, Zurina
- Date: 2019
- Subjects: Children's rights -- South Africa , Children -- Legal status, laws, etc --South Africa , Parent and child -- Research -- South Africa , Social work with youth -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/30474 , vital:30949
- Description: The unique historical stressors linked to South Africa’s apartheid legacy, continues to manifest in the form of economic exclusion, social exclusion, inequality and poverty, with parents being subjugated to service users and extenders rather than included as service advocates, particularly in the child justice system. Furthermore, policies and practices do not include, engage and support parents on an intra and interpersonal level. Parents of children in conflict with the law, experience their children’s charge or arrest as well as their subsequent journey through the child justice system as a crisis resulting in their need for emotional, informational, practical and professional support during the child justice process. The similarities and differences between the contexts of child protection and child justice in supporting parents illuminates the existing gaps in child justice legislation, policy and practice resulting in a lack of support for parents during the child justice process. In the Children’s Act 38 of 2005, it is recognised that parents have a legal responsibility towards their children and that in fulfilling this responsibility parents can access support services to assist them when they face challenges in fulfilling this responsibility. In contrast, despite 80 percent of children in conflict with the law being released into parental care and parents expressing the need for support in fulfilling their parental responsibility, in this regard the Child Justice Act 75 of 2008 fails to make provision for parents to access support services. The child justice system’s narrow focus on parents as service extenders contributes to parents’ being excluded from targeted support services resulting in parents’ support needs not being addressed. The lack of programmes and services aimed at supporting parents highlight the need for coordinated services that address the multiple stressors parents are exposed to. To this end, this study was aimed at coconstructing a practice model for supporting parents of children in conflict with the law. The theoretical lenses employed in the current study namely; the Ecological systems model and the Buffering effect model describes the various systems parents need support from and the type of support they need from their family, community and professionals. Guided by a qualitative approach, the present study integrated applied research, in particular intervention design and development with participatory action research as it allowed systematic collaboration during the research process to ensure rigour. This study involved participants from two research sites namely, the Nerina One- Stop Child Justice Centre in Port Elizabeth and the Reception, Assessment and Referral office at the Uitenhage magistrates’ court. Employing a non-probability purposive sampling method, this study facilitated the participation of parents of children in conflict with the law and child justice officials who met the inclusion criteria, in the co-design and development of a practice model for supporting parents of children in conflict with the law. Participants assumed an expert and collaborative role, which enabled the co-construction of knowledge, meaning and innovation of the practice model. Qualitative data collection methods namely, twelve focus groups and thirty two participant observations, were used to explore, co-construct, describe and design a practice model for supporting parents of children in conflict with the law during the child justice process. Thematic analyses was employed to condense the data, search for codes, categories, themes, relationships and patterns in the data. Due to the research approach and design, data analysis was ongoing and informed design and development of the practice model. Based on the thematic analysis and synthesis both descriptive and analytic themes emerged. To ensure trustworthiness, this study employed various strategies to strengthen commitment, rigour, transparency and coherence. In addition, the participative research process, the inclusion of multiple forms of qualitative inquiry and the significance of the study contributed to the validity and quality of the study. Ethical considerations applicable to the study included participants’ voluntary participation, their informed consent and ensuring participants’ privacy or maintaining confidentially. Various strategies were employed to prevent or minimise risk to participants. The findings showed that formal sources of support, in particular, offer opportunities for parents to access individual and family counselling, parenting advice, and peer support. The study also highlighted the importance of recognising parents as a subsystem in the child justice system offers potential opportunities for inclusion of parents as co-facilitators of parenting programmes or support groups, as peer supporters during the child justice process. Parents’ inclusion as a partner in the child justice system is highlighted as an opportunity for parents to be able to vi participate in child justice fora, oversight committees and accreditation committees to influence policy, services and budget allocations for services to support parents of children in conflict with the law. This study’s contribution to the existing body of knowledge is an integrated, multidisciplinary, multi-phase co-constructed practice model that would enable inclusion of, and support for, parents of children in conflict with the law prior to, during and after the child justice. The co-constructed practice model (a) involves a continuum of parent-centred support for and inclusion of parents prior to, during and after the child justice process; (b) advances an inclusive and collaborative child justice system that views parents as important stakeholders in determining the type of services they need and being involved in developing practice; and (c) promotes parents as equal partners in decision making and policy making to influence legislation, policy and practice in the child justice system.
- Full Text:
- Date Issued: 2019
A collaboratively constructed process model for understanding and supporting the work of the community volunteer in a community school
- Authors: Damons, Bruce Peter
- Date: 2017
- Subjects: Volunteer workers in education -- South Africa Community schools -- South Africa , Volunteers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15049 , vital:28116
- Description: This thesis sought to explore how community volunteers could be recruited, supported and sustained to assist a community school operating in difficult socioeconomic conditions in achieving basic school functionality. Through a collaborative process, the participants in the study attempted to address a significant gap in the literature, namely how this could be achieved in a way that would be beneficial both to the community volunteers and to the school itself. Based on existing literature, the vast majority of South African schools are struggling to reach the basic functionality levels required in terms of legislation. My interest in this topic was piqued while serving as principal of one such school; hence the focus in this thesis on whether schools would benefit in terms of achieving functionality if they partnered with the communities in which they are located. However, communities are seldom actively involved in the schools and school activities on an ongoing daily basis. In this thesis, I argue for an opportunity for schools and the community to collaborate in a way that would be mutually beneficial. In this, I was guided by the School-Based Complementary Learning Framework (SBCLF) in gaining a greater understanding of how multiple stakeholders could support a school to obtain basic functionality. A key stakeholder is the community in which a school is located, and the multidimensional framework provided a framework to understand why the community would want to get involved in the school. Following a Participatory Action Learning and Action Research (PALAR) design, I recruited 15 community volunteers from the existing pool at my then school; some of whom had been volunteering for over twelve years. We formed an action learning set where we collaboratively sought to understand the processes and conditions needed to recruit, support and sustain community volunteers and their involvement in the school. From this action learning set emerged a key advisors’ set, comprising five members of the action learning set, who were entrusted with the responsibility of planning, preparing and analysing the action learning set meetings. Transcripts and visual artefacts from the action learning set meetings and a focus group meeting of the school management team were analysed to generate data, complemented by secondary sources, such as documents. This participatory approach to data generation allowed the voice of every participant to be heard; agency was increased through active participation; and the sense of affiliation to the group was deepened. The iterative design of the research process further ensured that the participants also engaged in a critical discourse analysis of the emerging data, of which the trustworthiness was enhanced through the use of dialogic and process, catalytic, rhetoric, democratic and outcome validity. The emergence of the data through this collaborative engagement was underpinned by the ethical values of mutual respect; equality and inclusion; democratic participation; active learning; making a difference; collective action; and personal integrity. The findings revealed that community volunteers did add immense value to the school by supporting teaching and learning processes. However, the community volunteers also harboured expectations of material support and opportunities to develop skills. In addition, the study revealed that the hierarchical culture and structures present in most South African schools need to become more democratic and collaborative, with those working to make the school more functional, including community volunteers, being valued, acknowledged and supported. The participants also constructed their understanding of what a community school should be and do and how it should serve the interests of the children from the community. A process model was constructed from these findings regarding on ways to recruit, sustain and support community volunteers involved in community schools, specially designed so that schools could adapt it to suit individual contexts. This study is unique; I am not aware of any similar study ever having been conducted in a community school in South Africa. Furthermore, the collaborative approach used in the study helped ensure that the methodology used could be of value to principals and other school stakeholders in addressing the various complex challenges that confront schools in these contexts. Also, the findings will add to the theoretical body of knowledge around volunteerism, especially in difficult socioeconomic conditions.
- Full Text:
- Date Issued: 2017
- Authors: Damons, Bruce Peter
- Date: 2017
- Subjects: Volunteer workers in education -- South Africa Community schools -- South Africa , Volunteers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15049 , vital:28116
- Description: This thesis sought to explore how community volunteers could be recruited, supported and sustained to assist a community school operating in difficult socioeconomic conditions in achieving basic school functionality. Through a collaborative process, the participants in the study attempted to address a significant gap in the literature, namely how this could be achieved in a way that would be beneficial both to the community volunteers and to the school itself. Based on existing literature, the vast majority of South African schools are struggling to reach the basic functionality levels required in terms of legislation. My interest in this topic was piqued while serving as principal of one such school; hence the focus in this thesis on whether schools would benefit in terms of achieving functionality if they partnered with the communities in which they are located. However, communities are seldom actively involved in the schools and school activities on an ongoing daily basis. In this thesis, I argue for an opportunity for schools and the community to collaborate in a way that would be mutually beneficial. In this, I was guided by the School-Based Complementary Learning Framework (SBCLF) in gaining a greater understanding of how multiple stakeholders could support a school to obtain basic functionality. A key stakeholder is the community in which a school is located, and the multidimensional framework provided a framework to understand why the community would want to get involved in the school. Following a Participatory Action Learning and Action Research (PALAR) design, I recruited 15 community volunteers from the existing pool at my then school; some of whom had been volunteering for over twelve years. We formed an action learning set where we collaboratively sought to understand the processes and conditions needed to recruit, support and sustain community volunteers and their involvement in the school. From this action learning set emerged a key advisors’ set, comprising five members of the action learning set, who were entrusted with the responsibility of planning, preparing and analysing the action learning set meetings. Transcripts and visual artefacts from the action learning set meetings and a focus group meeting of the school management team were analysed to generate data, complemented by secondary sources, such as documents. This participatory approach to data generation allowed the voice of every participant to be heard; agency was increased through active participation; and the sense of affiliation to the group was deepened. The iterative design of the research process further ensured that the participants also engaged in a critical discourse analysis of the emerging data, of which the trustworthiness was enhanced through the use of dialogic and process, catalytic, rhetoric, democratic and outcome validity. The emergence of the data through this collaborative engagement was underpinned by the ethical values of mutual respect; equality and inclusion; democratic participation; active learning; making a difference; collective action; and personal integrity. The findings revealed that community volunteers did add immense value to the school by supporting teaching and learning processes. However, the community volunteers also harboured expectations of material support and opportunities to develop skills. In addition, the study revealed that the hierarchical culture and structures present in most South African schools need to become more democratic and collaborative, with those working to make the school more functional, including community volunteers, being valued, acknowledged and supported. The participants also constructed their understanding of what a community school should be and do and how it should serve the interests of the children from the community. A process model was constructed from these findings regarding on ways to recruit, sustain and support community volunteers involved in community schools, specially designed so that schools could adapt it to suit individual contexts. This study is unique; I am not aware of any similar study ever having been conducted in a community school in South Africa. Furthermore, the collaborative approach used in the study helped ensure that the methodology used could be of value to principals and other school stakeholders in addressing the various complex challenges that confront schools in these contexts. Also, the findings will add to the theoretical body of knowledge around volunteerism, especially in difficult socioeconomic conditions.
- Full Text:
- Date Issued: 2017
A combination of a stationary and non-stationary model to predict corporate failure in South Africa
- Authors: Court, Philip Wathen
- Date: 1994
- Subjects: Bankruptcy -- South Africa Business planning -- South Africa Business failures -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1183 , http://hdl.handle.net/10962/d1002800
- Description: Business failure should be of concern in most industralised countries and the importance of accurately evaluating the phenomenon from a management and investment point of view is enormous. Were it possible to predict failure with a certain degree of confidence, steps could be taken to rectify the situation and the benefit would accrue to all of the stakeholders in the macroenvironment. In essence, the profitability of a business is influenced by two sets of variables. In the first instance, it is influenced by a variety of internal (microeconomic) variables which are firm- specific and which management is generally able to control. A further distinction in this regard may be made between the financial and non-financial variables. In the second instance, it is generally accepted that profitability will be influenced by a number of external (macroeconomic) variables which are generally beyond the control of management. In the main, however, the profitability of the firm is generally determined by a combination of both sets of factors. To date, a great deal of research has been undertaken in an attempt to establish a reliable model which may be used to predict failure. This has mainly been confined to the microeconomic variables which can be used to predict failure and attempts have been made to isolate either a single financial ratio or a number of financial and non-financial variables which can be used to model corporate failure. The research has met with a certain degree of success although this appears to be confined to the economic environment to which the models have been applied. The models are less successful when applied to other macroenvironments. Limited research has been undertaken into the macroeconomic variables which contribute to business failure or to a combination of the two types of variables. It is appropriate therefore that further consideration be given to the establishment of a model incorporating ALL the variables which could contribute to corporate failure. The purpose of this research is to undertake an investigation of micro- and macroeconomic variables that are freely available to reserachers and which may be used in a failure prediction model. The intention is to obtain a comprehensive, yet simple model which can be used as an overall predictor of PENDING failure.
- Full Text:
- Date Issued: 1994
- Authors: Court, Philip Wathen
- Date: 1994
- Subjects: Bankruptcy -- South Africa Business planning -- South Africa Business failures -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1183 , http://hdl.handle.net/10962/d1002800
- Description: Business failure should be of concern in most industralised countries and the importance of accurately evaluating the phenomenon from a management and investment point of view is enormous. Were it possible to predict failure with a certain degree of confidence, steps could be taken to rectify the situation and the benefit would accrue to all of the stakeholders in the macroenvironment. In essence, the profitability of a business is influenced by two sets of variables. In the first instance, it is influenced by a variety of internal (microeconomic) variables which are firm- specific and which management is generally able to control. A further distinction in this regard may be made between the financial and non-financial variables. In the second instance, it is generally accepted that profitability will be influenced by a number of external (macroeconomic) variables which are generally beyond the control of management. In the main, however, the profitability of the firm is generally determined by a combination of both sets of factors. To date, a great deal of research has been undertaken in an attempt to establish a reliable model which may be used to predict failure. This has mainly been confined to the microeconomic variables which can be used to predict failure and attempts have been made to isolate either a single financial ratio or a number of financial and non-financial variables which can be used to model corporate failure. The research has met with a certain degree of success although this appears to be confined to the economic environment to which the models have been applied. The models are less successful when applied to other macroenvironments. Limited research has been undertaken into the macroeconomic variables which contribute to business failure or to a combination of the two types of variables. It is appropriate therefore that further consideration be given to the establishment of a model incorporating ALL the variables which could contribute to corporate failure. The purpose of this research is to undertake an investigation of micro- and macroeconomic variables that are freely available to reserachers and which may be used in a failure prediction model. The intention is to obtain a comprehensive, yet simple model which can be used as an overall predictor of PENDING failure.
- Full Text:
- Date Issued: 1994
A combination of platinum anticancer drugs and mangiferin causes increased efficacy in cancer cell lines
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
A combinatorial analysis of barred preferential arrangements
- Authors: Nkonkobe, Sithembele
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/36228 , vital:24530
- Description: For a non-negative integer n an ordered partition of a set Xn with n distinct elements is called a preferential arrangement (PA). A barred preferential arrangement (BPA) is a preferential arrangement with bars in between the blocks of the partition. An integer sequence an associated with the counting PA's of Xn has been intensely studied over a century and a half in many different contexts. In this thesis we develop a unified combinatorial framework to study the enumeration of BPAs and a special subclass of BPAs. The results of the study lead to a positive settlement of an open problem and a conjecture by Nelsen. We derive few important identities pertaining to the number of BPAs and restricted BPAs of an n element set using generating- functionology. Later we show that the number of restricted BPAs of Xn are intricately related to well-known numbers such as Eulerian numbers, Bell numbers, Poly-Bernoulli numbers and the number of equivalence classes of fuzzy subsets of Xn under some equivalent relation.
- Full Text:
- Date Issued: 2016
- Authors: Nkonkobe, Sithembele
- Date: 2016
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/36228 , vital:24530
- Description: For a non-negative integer n an ordered partition of a set Xn with n distinct elements is called a preferential arrangement (PA). A barred preferential arrangement (BPA) is a preferential arrangement with bars in between the blocks of the partition. An integer sequence an associated with the counting PA's of Xn has been intensely studied over a century and a half in many different contexts. In this thesis we develop a unified combinatorial framework to study the enumeration of BPAs and a special subclass of BPAs. The results of the study lead to a positive settlement of an open problem and a conjecture by Nelsen. We derive few important identities pertaining to the number of BPAs and restricted BPAs of an n element set using generating- functionology. Later we show that the number of restricted BPAs of Xn are intricately related to well-known numbers such as Eulerian numbers, Bell numbers, Poly-Bernoulli numbers and the number of equivalence classes of fuzzy subsets of Xn under some equivalent relation.
- Full Text:
- Date Issued: 2016
A combined modelling approach for simulating channel–wetland exchanges in large African river basins
- Authors: Makungu, Eunice J
- Date: 2020
- Subjects: Watersheds -- Africa , Watershed management -- Africa , Water resources development -- Africa -- International cooperation , Floodplain management -- Africa , Wetland ecology -- Simulation methods -- Africa , Wetland management -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/123288 , vital:35424
- Description: In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose.
- Full Text:
- Date Issued: 2020
A combined modelling approach for simulating channel–wetland exchanges in large African river basins
- Authors: Makungu, Eunice J
- Date: 2020
- Subjects: Watersheds -- Africa , Watershed management -- Africa , Water resources development -- Africa -- International cooperation , Floodplain management -- Africa , Wetland ecology -- Simulation methods -- Africa , Wetland management -- Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/123288 , vital:35424
- Description: In Africa, many large and extensive wetlands are hydrologically connected to rivers, and their environmental integrity, as well as their influence on downstream flow regimes, depends on the prevailing channel–wetland exchange processes. These processes are inherently complex and vary spatially and temporally. Understanding channel–wetland exchanges is therefore, indispensable for the effective management of wetlands and the associated river basins. However, this information is limited in most of the river basins containing large wetlands in Africa. Furthermore, it is important to understand the links between upstream and downstream flow regimes and the wetland dynamics themselves, specifically where there are water resource developments that may affect these links (upstream developments), or be affected by them (downstream developments). Hydrological modelling of the entire basin using basin-scale models that include wetland components in their structures can be used to provide the information required to manage water resources in such basins. However, the level of detail of wetland processes included in many basin-scale models is typically very low and the lack of understanding of the wetland dynamics makes it difficult to quantify the relevant parameters. Detailed hydraulic models represent the channel-wetland exchanges in a much more explicit manner, but require relatively more data and time resources to establish than coarser scale hydrological models. The main objective of this study was, therefore, to investigate the use of a detailed hydraulic wetland model to provide a better understanding of channel–wetland exchanges and wetland dynamics, and to use the results to improve the parameterisation of a basin-scale model. The study focused on improving the water resource assessments modelling of three data-scarce African river basins that contain large wetlands: the floodplains of the Luangwa and Upper Zambezi River basins and the Usangu wetland in the Upper Great Ruaha River basin. The overall objective was achieved through a combined modelling approach that uses a detailed high-resolution LISFLOOD-FP hydraulic model to inform the structure and parameters of the GW Pitman monthly hydrological model. The results from the LISFLOOD-FP were used to improve the understanding of the channel–wetland exchange dynamics and to establish the wetland parameters required in the GW Pitman model. While some wetland parameters were directly quantified from the LISFLOOD-FP model results, others, which are highly empirical, were estimated by manually calibrating the GW Pitman wetland sub-model implemented in excel spreadsheets containing the LISFLOOD-FP model results. Finally, the GW Pitman model with the inclusion of the estimated wetland parameters was applied for each basin and the results compared to the available downstream observed flow data. The two models have been successfully applied in southern Africa, with the GW Pitman model being one of the most widely applied hydrological models in this region. To address the issue of data scarcity, during setup of these models, the study mainly relied on the global datasets which clearly adds to the overall uncertainty of the modelling approach. However, this is a typical situation for most of the data scarce regions of the continent. A number of challenges were, however, faced during the setup of the LISFLOOD-FP, mainly due to the limitations of the data inputs. Some of the LISFLOOD-FP data inputs include boundary conditions (upstream and downstream), channel cross-sections and wetland topography. In the absence of observed daily flows to quantify the wetland upstream boundary conditions, monthly flow volumes simulated using the GW Pitman monthly model (without including the wetland sub-model) were disaggregated into daily flows using a disaggregation sub-model. The simulated wetland inflows were evaluated using the observed flow data for downstream gauging stations that include the wetland effects. The results highlighted that it is important to understand the possible impacts of each wetland on the downstream flow regime during the evaluations of the model simulation results. Although the disaggregation approach cannot be validated due to a lack of observed data, it at least enables the simulated monthly flows to be used in the daily time step hydraulic model. One of the recommendations is that improvements are required in gauging station networks to provide more observed information for the main river and the larger tributary inflows into these large and important wetland systems. Even a limited amount of newly observed data would be helpful to reduce some of the uncertainties in the combined modelling approach. The SRTM 90 m DEM (used to represent wetland topography) was filtered to reduce local variations and noise effects (mainly vegetation bias), but there were some pixels that falsely affect the inundation results, and the recently released vegetation-corrected DEMs are suggested to improve the simulation results. Channel cross-section values derived from global datasets should be examined because some widths estimated from the Andreadis et al. (2013) dataset were found to be over-generalised and did not reflect widths measured using high-resolution Google Earth in many places. There is an indication that channel cross-sections digitised from Google Earth images can be successfully used in the model setup except in densely vegetated swamps where the values are difficult to estimate, and in such situations, field measured cross-section data are required. Small channels such as those found in the Usangu wetland could play major role in the exchange dynamics, but digitising them all was not straightforward and only key ones were included in the model setup. Clearly, this inevitably introduced uncertainties in the simulated results, and future studies should consider applying methods that simplify extractions of most of these channels from high-resolution images to improve the simulated results. The study demonstrated that the wetland and channel physical characteristics, as well as the seasonal flow magnitude, largely influence the channel–wetland exchanges and wetland dynamics. The inundation results indicated that the area–storage and storage–inflow relationships form hysteretic curves, but the shape of these curves vary with flood magnitude and wetland type. Anticlockwise hysteresis curves were observed in both relationships for the floodplains (Luangwa and Barotse), whereas there appears to be no dominant curve type for the Usangu wetlands. The lack of well-defined hysteretic relationships in the Usangu could be related to some of the difficulties (and resulting uncertainties) that were experienced in setting up the model for this wetland. The storage–inflow relationships in all wetlands have quite complex rising limbs due to multiple flow peaks during the main wet season. The largest inundation area and storage volume for the Barotse and Usangu wetlands occurred after the peak discharge of the wet season, a result that is clearly related to the degree of connectivity between the main channel and those areas of the wetlands that are furthest away from the channel. Hysteresis effects were found to increase with an increase in flood magnitudes and temporal variations in the wetland inflows. Overall, hysteresis behaviour is common in large wetlands and it is recommended that hysteresis curves should be reflected in basin-scale modelling of large river basins with substantial wetland areas. At a daily time scale, inflow–outflow relationships showed a significant peak reduction and a delayed time to peak of several weeks in the Barotse and Usangu wetlands, whereas the attenuation effects of the Luangwa floodplain are minimal. To a large extent, the LISFLOOD-FP results provided useful information to establish wetland parameters and assess the structure of Pitman wetland sub-model. The simple spreadsheet used to estimate wetland parameters did not account for the wetland water transfers from the upstream to the next section downstream (the condition that is included in the LISFLOOD-FP model) for the case when the wetlands were distributed across more than one sub-basin. It is recommended that a method that allows for the upstream wetland inflows and the channel inflows should be included in the spreadsheet. The same is true to the Pitman model structure, and a downstream transfer of water can be modelled through return flows to the channel. The structure of the wetland sub-model was modified to allow an option for the return flows to occur at any time during the simulation period to provide for types of wetlands (e.g. the Luangwa) where spills from the channel and drainage back to the channel occur simultaneously. The setup of the GW Pitman model with the inclusion of wetland parameters improved the simulation results. However, the results for the Usangu wetlands were not very satisfactory and the collection of additional field data related to exchange dynamics is recommended to achieve improvements. The impacts of the Luangwa floodplain on the flow regime of the Luangwa River are very small at the monthly time scale, whereas the Barotse floodplain system and the Usangu wetlands extensively regulate flows of the Zambezi River and the Great Ruaha River, respectively. The results highlighted the possibilities of regionalising some wetland parameters using an understanding of wetland physical characteristics and their water exchange dynamics. However, some parameters remain difficult to quantify in the absence of site-specific information about the water exchange dynamics. The overall conclusion is that the approach implemented in this study presents an important step towards the improvements of water resource assessments modelling for research and practical purposes in data-scarce river basins. This approach is not restricted to the two used models, as it can be applied using different model combinations to achieve similar study purpose.
- Full Text:
- Date Issued: 2020
A commentary on the eleventh book of the Punica of Silius Italicus
- Matier, K O (Kenneth Ogilvie)
- Authors: Matier, K O (Kenneth Ogilvie)
- Date: 1980
- Subjects: Silius Italicus, Tiberius Catius. Punica Latin literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3624 , http://hdl.handle.net/10962/d1007535
- Description: Preface: The scope of the commentary is limited. I have been concerned with establishing the diction of Silius in Book 11. I have shown which words are confined to epic, which words are poetic and which words are prosaic. I have not attempted to establish whether there is a correlation between Silius' use of 'poetic' and' prosaic' words and the content of what he is saying. But I have noticed that Silius frequently uses prosaic words when he is following Livy or some other historical source. In other cases, Silius may be using prosaic words because of his own training as an orator. He is clearly indebted to Cicero. Nor have I attempted to establish whether there is any particular effect when Silius uses a'poetic' or 'prosaic' word or phrase or construction. I have been influenced by considerations of length and also by the fact that I believe any such attempted interpretation, although it might produce valuable results, would of necessity be much more subjective than what I have actually done. I leave any such interpretation to future researchers of Silius.
- Full Text:
- Date Issued: 1980
- Authors: Matier, K O (Kenneth Ogilvie)
- Date: 1980
- Subjects: Silius Italicus, Tiberius Catius. Punica Latin literature -- History and criticism
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3624 , http://hdl.handle.net/10962/d1007535
- Description: Preface: The scope of the commentary is limited. I have been concerned with establishing the diction of Silius in Book 11. I have shown which words are confined to epic, which words are poetic and which words are prosaic. I have not attempted to establish whether there is a correlation between Silius' use of 'poetic' and' prosaic' words and the content of what he is saying. But I have noticed that Silius frequently uses prosaic words when he is following Livy or some other historical source. In other cases, Silius may be using prosaic words because of his own training as an orator. He is clearly indebted to Cicero. Nor have I attempted to establish whether there is any particular effect when Silius uses a'poetic' or 'prosaic' word or phrase or construction. I have been influenced by considerations of length and also by the fact that I believe any such attempted interpretation, although it might produce valuable results, would of necessity be much more subjective than what I have actually done. I leave any such interpretation to future researchers of Silius.
- Full Text:
- Date Issued: 1980
A commercial process development for plant food formulation using polyprotic acids from natural extracts as chelating agents
- Authors: Ndibewu, Peter Papoh
- Date: 2005
- Subjects: Chelates , Lemon juice , Liquid fertilizers
- Language: English
- Type: Thesis , Doctoral , DTech (Chemistry)
- Identifier: vital:10368 , http://hdl.handle.net/10948/153 , Chelates , Lemon juice , Liquid fertilizers
- Description: The citrus industry is one of South Africa's largest agricultural sectors in terms of export earnings with lemon fruits and juice as a trendsetter due to their high grade quality. According to growers, the Eastern Cape Province of South Africa alone produces an excess of about 10-14,000 tons of lemon juice which is presently of no economic value due to the sour taste and “bitterness”. As a result of this excess and in order to make use of the polyprotic acids naturally occurring in the lemon juice, four fertilizer nutrient mixtures are formulated, using lemon juice as base. From a conceptual scientific approach, characterization (physico-chemical and functional properties determinations) of Eureka Lemon fruit juices were undertaken, followed by smaller scale batch formulation experiments. On the basis that these lemon juice-based fertilizer mixtures are prepared following standard liquid fertilizer formulation guidelines, a field test was conducted to evaluate their potential effectiveness to influence plant growth. A growth chamber testing on tomato plants revealed high growth response (> 99.9 % certainty) potential in two of the semi-organic mixtures formulated while the organic mixture showed a relatively good growth rate as compared to the control (pure tap water). According to statistical analysis (ANOVA) comparison, two of the semi-organic mixtures performed considerably better than the two commercial samples evaluated. Potential benefits profoundly associated with these nutrient mixtures as compared to similar liquid fertilizer products on the market is that most nutrients are chelated and dissolved in solution. Also, the mixtures contain all necessary nutrients including plant growth substances required for healthier plant growth. The most important socioeconomic impact is the value addition to the technology chain in the citrus industry. The use of fluid fertilizers in significant quantities is less than twenty years old. Nevertheless, growth has been so rapid that in South Africa demand for mixed liquid fertilizer has greatly increased from 90 000 tons NPK & blended micronutrients in 1955 to more than 600 000 per annum tons today (Report 41/2003, Department of Minerals and Energy). The liquid fertilizers market is sparsely specialized with major competitors like Omnia, Kynoch and Foskor supplying more than 50 % of the market demand. Amongst the nutrient mixtures formulated, mixture one is an NPK (1-1-2) based nutrient mixture containing both secondary nutrients (0.5 % Mg & 1.0 % Ca) and seven micronutrients (0.1 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co). The composition of this mixture offers the formula a potential to be used as a general purpose (all stages of plant growth) fertilization mixture in view of its balanced composition (containing all essential plant nutrients). Mixture two contains essentially the micronutrients and in higher concentrations (0.3 % Fe, 0.3 % Cu, 0.1 % Zn, 0.2 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co) as compared to mixture one except for boron, molybdenum and cobalt. The concentration of the micronutrients contained in this mixture is adequately high which offers a potential for it to be used in supplementing nutrition in plants with critical micronutrient-deficient symptoms. Mixture three is very similar to mixture two (1.0 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 Mn, 0.05 % B, 0.0005 % Mo and 0.0005 % Co) except that the concentrations of all seven micronutrients are considerably less than those of contained in mixture two. However, the concentration of iron in this mixture is as high as 1.0 %. The mixture has a potential to be used in high iron-deficient situations. Mixture four is an organic formula with relatively low nutrient concentrations (NPK-0.02-0.02-1, 0.27 % Mg, 0.02 % Ca, 0.008 % Fe, 0.26 % Cu, 0.012 % Zn, 0.009 % Mn). Nevertheless, this mixture is appealing for organically grown crops where the use of chemicals is prohibited by standards. These lemon juice-based nutrient mixtures were further characterized and tested for stability and storability over a period of eight weeks. This study revealed no major change in the physical quality (colour, pH and “salt out” effect). The basic formulation methodology is a two-step procedure that involves filtration of the lemon juice to remove membranous materials, mixing at ambient temperature and stabilization of the nutrient mixtures. However, for the organic nutrient formula mix, filtration follows after extraction of nutrients from plant materials using the lemon juice.
- Full Text:
- Date Issued: 2005
- Authors: Ndibewu, Peter Papoh
- Date: 2005
- Subjects: Chelates , Lemon juice , Liquid fertilizers
- Language: English
- Type: Thesis , Doctoral , DTech (Chemistry)
- Identifier: vital:10368 , http://hdl.handle.net/10948/153 , Chelates , Lemon juice , Liquid fertilizers
- Description: The citrus industry is one of South Africa's largest agricultural sectors in terms of export earnings with lemon fruits and juice as a trendsetter due to their high grade quality. According to growers, the Eastern Cape Province of South Africa alone produces an excess of about 10-14,000 tons of lemon juice which is presently of no economic value due to the sour taste and “bitterness”. As a result of this excess and in order to make use of the polyprotic acids naturally occurring in the lemon juice, four fertilizer nutrient mixtures are formulated, using lemon juice as base. From a conceptual scientific approach, characterization (physico-chemical and functional properties determinations) of Eureka Lemon fruit juices were undertaken, followed by smaller scale batch formulation experiments. On the basis that these lemon juice-based fertilizer mixtures are prepared following standard liquid fertilizer formulation guidelines, a field test was conducted to evaluate their potential effectiveness to influence plant growth. A growth chamber testing on tomato plants revealed high growth response (> 99.9 % certainty) potential in two of the semi-organic mixtures formulated while the organic mixture showed a relatively good growth rate as compared to the control (pure tap water). According to statistical analysis (ANOVA) comparison, two of the semi-organic mixtures performed considerably better than the two commercial samples evaluated. Potential benefits profoundly associated with these nutrient mixtures as compared to similar liquid fertilizer products on the market is that most nutrients are chelated and dissolved in solution. Also, the mixtures contain all necessary nutrients including plant growth substances required for healthier plant growth. The most important socioeconomic impact is the value addition to the technology chain in the citrus industry. The use of fluid fertilizers in significant quantities is less than twenty years old. Nevertheless, growth has been so rapid that in South Africa demand for mixed liquid fertilizer has greatly increased from 90 000 tons NPK & blended micronutrients in 1955 to more than 600 000 per annum tons today (Report 41/2003, Department of Minerals and Energy). The liquid fertilizers market is sparsely specialized with major competitors like Omnia, Kynoch and Foskor supplying more than 50 % of the market demand. Amongst the nutrient mixtures formulated, mixture one is an NPK (1-1-2) based nutrient mixture containing both secondary nutrients (0.5 % Mg & 1.0 % Ca) and seven micronutrients (0.1 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co). The composition of this mixture offers the formula a potential to be used as a general purpose (all stages of plant growth) fertilization mixture in view of its balanced composition (containing all essential plant nutrients). Mixture two contains essentially the micronutrients and in higher concentrations (0.3 % Fe, 0.3 % Cu, 0.1 % Zn, 0.2 % Mn, 0.02 % B, 0.0005 % Mo and 0.0005 % Co) as compared to mixture one except for boron, molybdenum and cobalt. The concentration of the micronutrients contained in this mixture is adequately high which offers a potential for it to be used in supplementing nutrition in plants with critical micronutrient-deficient symptoms. Mixture three is very similar to mixture two (1.0 % Fe, 0.05 % Cu, 0.05 % Zn, 0.05 Mn, 0.05 % B, 0.0005 % Mo and 0.0005 % Co) except that the concentrations of all seven micronutrients are considerably less than those of contained in mixture two. However, the concentration of iron in this mixture is as high as 1.0 %. The mixture has a potential to be used in high iron-deficient situations. Mixture four is an organic formula with relatively low nutrient concentrations (NPK-0.02-0.02-1, 0.27 % Mg, 0.02 % Ca, 0.008 % Fe, 0.26 % Cu, 0.012 % Zn, 0.009 % Mn). Nevertheless, this mixture is appealing for organically grown crops where the use of chemicals is prohibited by standards. These lemon juice-based nutrient mixtures were further characterized and tested for stability and storability over a period of eight weeks. This study revealed no major change in the physical quality (colour, pH and “salt out” effect). The basic formulation methodology is a two-step procedure that involves filtration of the lemon juice to remove membranous materials, mixing at ambient temperature and stabilization of the nutrient mixtures. However, for the organic nutrient formula mix, filtration follows after extraction of nutrients from plant materials using the lemon juice.
- Full Text:
- Date Issued: 2005
A comparative analysis of anti-corruption legislation and anti-corruption agencies in the Eastern Cape and Northern Cape provices : a governance perspective
- Authors: Majila, Victoria Thozama
- Date: 2012
- Subjects: Political corruption -- South Africa , Misconduct in office -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8179 , http://hdl.handle.net/10948/2117 , Political corruption -- South Africa , Misconduct in office -- South Africa
- Description: This thesis analysed and compared the effectiveness of the anti-corruption legislation and anti-corruption agencies in the Eastern Cape and Northern Cape provinces. The thesis consists of six chapters. This study is based on the assumption that the struggle against corruption is best approached by developing a system of laws, institutions and supporting practices which promote integrity and make corrupt conduct a high-risk activity. It is imperative that a systemic approach is embarked upon in order to address the manner in which the major institutions and processes of the state are conquered and exploited by corrupt individuals and groups. With the magnitude in which hurdles exist that hamper the effectiveness of the country's anti-corruption legislation and anti-corruption agencies; South Africa is incapable of curbing corruption. With the purpose to determine a desired state of affairs, characteristics of effective anti-corruption agencies and anti-corruption legislation were presented. These served as a yardstick in measuring how effective such agencies and legislation are in South Africa. Reasons for failure of agencies and legislation are discussed. After discussing types of anti-corruption agencies, those that perform better than ix others were identified. Through literature review, the status quo concerning anti-corruption initiatives in South Africa was assessed. It was revealed that the level of the success of South African anti-corruption agencies and legislation has been limited. In the case of anti-corruption agencies, weaknesses such as fragmentation; insufficient coordination; poor delineation of responsibility; and assimilation of corruption work into a broader mandate were identified as major causes. Measures that are needed, such as informed citizens; a need to foster and sustain high levels of professional and ethically imbued civil servants; and legislation that supports the transition towards a corruption-free society that are needed to complement implementation of anti-corruption legislation, were also recognised. Ways of addressing such shortcomings that the writers identified are also presented. The methodology and design followed in the study are described. This is followed by the analysis and interpretation of the survey. The research findings are then presented. Based on the findings a number of recommendations that would assist in improving the effectiveness of anticorruption agencies and anti-corruption legislation are made. Flowing from the discussion of effective anti-corruption models that were identified by literature a model that would be ideal for South Africa is recommended.
- Full Text:
- Date Issued: 2012
- Authors: Majila, Victoria Thozama
- Date: 2012
- Subjects: Political corruption -- South Africa , Misconduct in office -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8179 , http://hdl.handle.net/10948/2117 , Political corruption -- South Africa , Misconduct in office -- South Africa
- Description: This thesis analysed and compared the effectiveness of the anti-corruption legislation and anti-corruption agencies in the Eastern Cape and Northern Cape provinces. The thesis consists of six chapters. This study is based on the assumption that the struggle against corruption is best approached by developing a system of laws, institutions and supporting practices which promote integrity and make corrupt conduct a high-risk activity. It is imperative that a systemic approach is embarked upon in order to address the manner in which the major institutions and processes of the state are conquered and exploited by corrupt individuals and groups. With the magnitude in which hurdles exist that hamper the effectiveness of the country's anti-corruption legislation and anti-corruption agencies; South Africa is incapable of curbing corruption. With the purpose to determine a desired state of affairs, characteristics of effective anti-corruption agencies and anti-corruption legislation were presented. These served as a yardstick in measuring how effective such agencies and legislation are in South Africa. Reasons for failure of agencies and legislation are discussed. After discussing types of anti-corruption agencies, those that perform better than ix others were identified. Through literature review, the status quo concerning anti-corruption initiatives in South Africa was assessed. It was revealed that the level of the success of South African anti-corruption agencies and legislation has been limited. In the case of anti-corruption agencies, weaknesses such as fragmentation; insufficient coordination; poor delineation of responsibility; and assimilation of corruption work into a broader mandate were identified as major causes. Measures that are needed, such as informed citizens; a need to foster and sustain high levels of professional and ethically imbued civil servants; and legislation that supports the transition towards a corruption-free society that are needed to complement implementation of anti-corruption legislation, were also recognised. Ways of addressing such shortcomings that the writers identified are also presented. The methodology and design followed in the study are described. This is followed by the analysis and interpretation of the survey. The research findings are then presented. Based on the findings a number of recommendations that would assist in improving the effectiveness of anticorruption agencies and anti-corruption legislation are made. Flowing from the discussion of effective anti-corruption models that were identified by literature a model that would be ideal for South Africa is recommended.
- Full Text:
- Date Issued: 2012
A comparative analysis of aspects of criminal and civil forfeitures: suggestions for South African asset forfeiture law reform
- Ndzengu, Nkululeko Christopher
- Authors: Ndzengu, Nkululeko Christopher
- Date: 2017
- Subjects: Forfeiture -- South Africa , Forfeiture -- South Africa -- Criminal provisions Reparation (Criminal justice) -- South Africa
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: http://hdl.handle.net/10948/14267 , vital:27501
- Description: In order for the proceeds of unlawful activities to be completely dislodged from the criminals’ hands, the latter should be effectively deterred from allowing their assets to be used to execute or facilitate the commission of offences. When properly exacted, in the interests of justice and within the existing constitutional framework, the legal process known as asset forfeiture should ensure that crime never pays. Asset forfeiture refers to both criminal forfeiture, which is conviction based following the United Kingdom asset forfeiture regime and civil forfeiture, which is non-conviction based following the United States of America one.2 Chapter 5 provisions of the Prevention of Organised Crime Act3 (hereafter POCA) provides for court, Basdeo M – Search, Seizure and Asset Forfeiture in the South African Criminal Justice System: Drawing a Balance between Public Utility and Constitutional Rights (2013) LLD, University of South Africa in Chapter 5 where a comprehensive comparative study of SA POCA and United States of America’s asset forfeiture and origin is undertaken. 3 Act 121 of applications for a restraint, confiscation and realisation for the recovery of proceeds of unlawful activities. The restraint is invoked when a suspect is to be charged or has been charged or prosecuted, there are reasonable grounds to believe that a conviction may follow and that a confiscation order may be made. Chapter 6 provisions of POCA provide for court applications for preservation and forfeiture order targeting both the proceeds of unlawful activities and removal from public circulation of instruments or assets used in the commission of offences where the guilt of the wrongdoer is not relevant. POCA has a Schedule with 34 items setting out examples of offences in relation to which civil forfeiture may be invoked. When the State discharges this noble professed task in the name of public safety, security and crime combating, legal challenges arise. This is more so within a constitutional democratic context where both individual and property rights are enshrined and protected. This study deals with some of these challenges. To the mind of a legal researcher, the law of asset forfeiture is, in this process, moulded and developed. South Africa (a developing country), Canada and New Zealand (developed countries in the north and southern hemispheres) have constitutional democracies. They also have asset forfeiture regimes, which attracted the attention of the researcher. The question is: can the developing country learn some best practices from the developed countries in this particular field? It would be interesting to establish this and the level of development of this field in the three countries under study. South Africa, with no federal government, has nine Provinces, single asset forfeiture legislation5 (combining both criminal forfeiture i.e. restraint, confiscation and realisation applications and civil forfeiture i.e. preservation and forfeiture applications), and a criminal statute6 applicable to all such Provinces. It also has, like Canada and New Zealand, pockets of asset forfeiture provisions embedded in various statutes. There is only one asset forfeiture office under the umbrella of the National Prosecuting Authority.7 It has branches8 in the Provinces, invoking the provisions of POCA, since 1999. It is not part of the police department. The researcher joined the South African Port Elizabeth branch in March 2003, Bloemfontein, Kimberly and Mmabatho branches from 2010 to 2011, July 2012 onwards in the Port Elizabeth and has practical experience in this regard. The Prevention of Organised Crime Act 121 of 1998. The Namibian POCA 29 of 2004 is almost a replica of the South African POCA except that the former makes express recognition of the victims of the underlying victims. The Criminal Procedure Act, 51 of 1977 (as amended). The Asset Forfeiture Unit (AFU) with its Head Office situated in Pretoria under the umbrella of the National Prosecution Authority, which Raylene Keightley in Young S Civil Forfeiture of Criminal Property Legal Measures for Targeting the Proceeds of Crime (2009) Cheltenham Edward Elgar Publishing, Inc.: Northampton, MA at 94 calls a specialist implementation agency. In Pretoria, Johannesburg, Cape Town, Port Elizabeth, East London, Durban, Bloemfontein, Kimberley, Mmabatho, Mpumalanga and Limpopo. It comprises of eleven Provinces to which the Criminal Code of Canada, the Controlled Drugs and Substances Act 1996 and a host of other statutes apply. Eight of the eleven Provinces have their own and distinct primary stand-alone asset forfeiture statutes introducing civil forfeiture10 as more fully explained in Chapter 2 of this study.
- Full Text:
- Date Issued: 2017
- Authors: Ndzengu, Nkululeko Christopher
- Date: 2017
- Subjects: Forfeiture -- South Africa , Forfeiture -- South Africa -- Criminal provisions Reparation (Criminal justice) -- South Africa
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: http://hdl.handle.net/10948/14267 , vital:27501
- Description: In order for the proceeds of unlawful activities to be completely dislodged from the criminals’ hands, the latter should be effectively deterred from allowing their assets to be used to execute or facilitate the commission of offences. When properly exacted, in the interests of justice and within the existing constitutional framework, the legal process known as asset forfeiture should ensure that crime never pays. Asset forfeiture refers to both criminal forfeiture, which is conviction based following the United Kingdom asset forfeiture regime and civil forfeiture, which is non-conviction based following the United States of America one.2 Chapter 5 provisions of the Prevention of Organised Crime Act3 (hereafter POCA) provides for court, Basdeo M – Search, Seizure and Asset Forfeiture in the South African Criminal Justice System: Drawing a Balance between Public Utility and Constitutional Rights (2013) LLD, University of South Africa in Chapter 5 where a comprehensive comparative study of SA POCA and United States of America’s asset forfeiture and origin is undertaken. 3 Act 121 of applications for a restraint, confiscation and realisation for the recovery of proceeds of unlawful activities. The restraint is invoked when a suspect is to be charged or has been charged or prosecuted, there are reasonable grounds to believe that a conviction may follow and that a confiscation order may be made. Chapter 6 provisions of POCA provide for court applications for preservation and forfeiture order targeting both the proceeds of unlawful activities and removal from public circulation of instruments or assets used in the commission of offences where the guilt of the wrongdoer is not relevant. POCA has a Schedule with 34 items setting out examples of offences in relation to which civil forfeiture may be invoked. When the State discharges this noble professed task in the name of public safety, security and crime combating, legal challenges arise. This is more so within a constitutional democratic context where both individual and property rights are enshrined and protected. This study deals with some of these challenges. To the mind of a legal researcher, the law of asset forfeiture is, in this process, moulded and developed. South Africa (a developing country), Canada and New Zealand (developed countries in the north and southern hemispheres) have constitutional democracies. They also have asset forfeiture regimes, which attracted the attention of the researcher. The question is: can the developing country learn some best practices from the developed countries in this particular field? It would be interesting to establish this and the level of development of this field in the three countries under study. South Africa, with no federal government, has nine Provinces, single asset forfeiture legislation5 (combining both criminal forfeiture i.e. restraint, confiscation and realisation applications and civil forfeiture i.e. preservation and forfeiture applications), and a criminal statute6 applicable to all such Provinces. It also has, like Canada and New Zealand, pockets of asset forfeiture provisions embedded in various statutes. There is only one asset forfeiture office under the umbrella of the National Prosecuting Authority.7 It has branches8 in the Provinces, invoking the provisions of POCA, since 1999. It is not part of the police department. The researcher joined the South African Port Elizabeth branch in March 2003, Bloemfontein, Kimberly and Mmabatho branches from 2010 to 2011, July 2012 onwards in the Port Elizabeth and has practical experience in this regard. The Prevention of Organised Crime Act 121 of 1998. The Namibian POCA 29 of 2004 is almost a replica of the South African POCA except that the former makes express recognition of the victims of the underlying victims. The Criminal Procedure Act, 51 of 1977 (as amended). The Asset Forfeiture Unit (AFU) with its Head Office situated in Pretoria under the umbrella of the National Prosecution Authority, which Raylene Keightley in Young S Civil Forfeiture of Criminal Property Legal Measures for Targeting the Proceeds of Crime (2009) Cheltenham Edward Elgar Publishing, Inc.: Northampton, MA at 94 calls a specialist implementation agency. In Pretoria, Johannesburg, Cape Town, Port Elizabeth, East London, Durban, Bloemfontein, Kimberley, Mmabatho, Mpumalanga and Limpopo. It comprises of eleven Provinces to which the Criminal Code of Canada, the Controlled Drugs and Substances Act 1996 and a host of other statutes apply. Eight of the eleven Provinces have their own and distinct primary stand-alone asset forfeiture statutes introducing civil forfeiture10 as more fully explained in Chapter 2 of this study.
- Full Text:
- Date Issued: 2017
A comparative analysis of the enforcement of market abuse provisions
- Authors: Chitimira, Howard
- Date: 2012
- Subjects: Corporation law -- South Africa , Insider trading in securities -- South Africa , Securities -- South Africa , Efficient market theory , Securities fraud
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:10240 , http://hdl.handle.net/10948/d1015008
- Description: Market abuse practices may directly or indirectly give rise to diverse problems such as inaccurate stock market prices, low public investor confidence, reduced market integrity and poor efficiency in the affected financial markets. This thesis reveals that three major forms of market abuse, namely insider trading, prohibited trading practices (trade-based market manipulation) and the making or publication of false, misleading or deceptive statements, promises and forecasts relating to listed securities (disclosure-based market manipulation) are prohibited in South Africa. However, although South Africa has had market abuse legislation for about 30 years, and must be commended for its great effort to enhance market integrity by combating market abuse practices, the enforcement of such legislation is still problematic. Moreover, in spite of the fact that there is no empirical data or accurate figures quantifying the occurrence and extent of market abuse activities in the South African financial markets, this thesis submits that market abuse practices are still to be completely eradicated. Accordingly, this thesis suggests that the aforementioned problem might have been aggravated by inter alia, various gaps, flaws and/or inconsistent implementation and enforcement of the market abuse legislation in South Africa. To this end, the anti-market abuse enforcement framework under the Securities Services Act 36 of 2004 is analysed to investigate its adequacy. The co-operation and role of the Financial Services Board, the courts, the Directorate of Market Abuse and other relevant stakeholders is also examined and discussed. Moreover, the co-operation between the Financial Services Board and similar international agencies is discussed to gauge its effectiveness in relation to the combating of cross-border market abuse practices. The adequacy of the awareness and preventative measures in place to curb market abuse practices is also investigated to determine whether such measures are robust enough to combat other new challenges that were posed by the 2007 to 2009 global financial crisis. Furthermore, a comparative analysis is undertaken of the enforcement of the market abuse prohibition in other jurisdictions, namely the United States of America, the United Kingdom, the European Union and Australia. This was done to investigate the relevant lessons that can be learnt or adopted from these jurisdictions. The thesis further discusses the adequacy of the recently introduced provisions of the Financial Markets Bill as well as the subsequent market abuse provisions of the Financial Markets Bill 2012. The thesis highlights that the aforementioned Bills are positive attempts by the policy makers to improve the enforcement of the market abuse provisions in South Africa. Nonetheless, the thesis reveals that most of the shortcomings contained in the Securities Services Act 36 of 2004 were duplicated in the Financial Markets Bill and the Financial Markets Bill 2012. In light of this, it remains to be seen whether the market abuse provisions contained in the Financial Markets Bill and/or the Financial Markets Bill 2012 will improve the combating of market abuse practices in South Africa. Consequently, it is hoped that the relevant market abuse provisions of the Securities Services Act 36 of 2004, the Financial Markets Bill and/or the Financial Markets Bill 2012 will be comprehensively reviewed in regard to the recommendations made in this thesis. To this end, the thesis proposes a viable anti-market abuse model and policy framework and sets out both policy objectives and provisions which policy makers could use to strengthen some of the market abuse provisions in South Africa.
- Full Text:
- Date Issued: 2012
- Authors: Chitimira, Howard
- Date: 2012
- Subjects: Corporation law -- South Africa , Insider trading in securities -- South Africa , Securities -- South Africa , Efficient market theory , Securities fraud
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:10240 , http://hdl.handle.net/10948/d1015008
- Description: Market abuse practices may directly or indirectly give rise to diverse problems such as inaccurate stock market prices, low public investor confidence, reduced market integrity and poor efficiency in the affected financial markets. This thesis reveals that three major forms of market abuse, namely insider trading, prohibited trading practices (trade-based market manipulation) and the making or publication of false, misleading or deceptive statements, promises and forecasts relating to listed securities (disclosure-based market manipulation) are prohibited in South Africa. However, although South Africa has had market abuse legislation for about 30 years, and must be commended for its great effort to enhance market integrity by combating market abuse practices, the enforcement of such legislation is still problematic. Moreover, in spite of the fact that there is no empirical data or accurate figures quantifying the occurrence and extent of market abuse activities in the South African financial markets, this thesis submits that market abuse practices are still to be completely eradicated. Accordingly, this thesis suggests that the aforementioned problem might have been aggravated by inter alia, various gaps, flaws and/or inconsistent implementation and enforcement of the market abuse legislation in South Africa. To this end, the anti-market abuse enforcement framework under the Securities Services Act 36 of 2004 is analysed to investigate its adequacy. The co-operation and role of the Financial Services Board, the courts, the Directorate of Market Abuse and other relevant stakeholders is also examined and discussed. Moreover, the co-operation between the Financial Services Board and similar international agencies is discussed to gauge its effectiveness in relation to the combating of cross-border market abuse practices. The adequacy of the awareness and preventative measures in place to curb market abuse practices is also investigated to determine whether such measures are robust enough to combat other new challenges that were posed by the 2007 to 2009 global financial crisis. Furthermore, a comparative analysis is undertaken of the enforcement of the market abuse prohibition in other jurisdictions, namely the United States of America, the United Kingdom, the European Union and Australia. This was done to investigate the relevant lessons that can be learnt or adopted from these jurisdictions. The thesis further discusses the adequacy of the recently introduced provisions of the Financial Markets Bill as well as the subsequent market abuse provisions of the Financial Markets Bill 2012. The thesis highlights that the aforementioned Bills are positive attempts by the policy makers to improve the enforcement of the market abuse provisions in South Africa. Nonetheless, the thesis reveals that most of the shortcomings contained in the Securities Services Act 36 of 2004 were duplicated in the Financial Markets Bill and the Financial Markets Bill 2012. In light of this, it remains to be seen whether the market abuse provisions contained in the Financial Markets Bill and/or the Financial Markets Bill 2012 will improve the combating of market abuse practices in South Africa. Consequently, it is hoped that the relevant market abuse provisions of the Securities Services Act 36 of 2004, the Financial Markets Bill and/or the Financial Markets Bill 2012 will be comprehensively reviewed in regard to the recommendations made in this thesis. To this end, the thesis proposes a viable anti-market abuse model and policy framework and sets out both policy objectives and provisions which policy makers could use to strengthen some of the market abuse provisions in South Africa.
- Full Text:
- Date Issued: 2012
A comparative analysis of the rights of the child with particular reference to child soldiers
- Authors: Anwo, Joel Olasunkanmi
- Date: 2008
- Subjects: Children's rights -- Child welfare -- Demobilization of children , Disarmament -- Reintegration
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:11108 , http://hdl.handle.net/10353/102 , Children's rights -- Child welfare -- Demobilization of children , Disarmament -- Reintegration
- Description: The recruitment, enlistment and forceful conscription of children as soldiers is a cause for grave concern all over the world and most especially in Africa, where years of factional fighting, civil wars and cross border conflicts have raged, children and youth have been pulled into violence not only as victims, but also as perpetrators. The involvement of children in war posses a severe challenge to prevailing moral and legal norms of the conduct of modern warfare. A major problem and most controversial issue, among others, is on the age at which children should be eligible to become combatants. Children, who may be viewed as a valuable resource due to their often inherent malleability, wish to avenge family member(s) killed in war, sense of immunity to danger, and or feeling of power in participating in the violence. Can the use of children as soldiers be effectively regulated in Africa? All efforts to assist child soldiers in recovering from the devastating effects of wars often unwillingly helped promote the growing number of child soldiers. This is in part because wars are now more fought internally among rebel armies and factions vying for power with the government and thus enlist children into their various armies. The study comes to a conclusion that drastic steps need to be taken to ameliorate this unfortunate situation. This formed the basis of the recommendations offered in the thesis to assist the African continent.
- Full Text:
- Date Issued: 2008
- Authors: Anwo, Joel Olasunkanmi
- Date: 2008
- Subjects: Children's rights -- Child welfare -- Demobilization of children , Disarmament -- Reintegration
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: vital:11108 , http://hdl.handle.net/10353/102 , Children's rights -- Child welfare -- Demobilization of children , Disarmament -- Reintegration
- Description: The recruitment, enlistment and forceful conscription of children as soldiers is a cause for grave concern all over the world and most especially in Africa, where years of factional fighting, civil wars and cross border conflicts have raged, children and youth have been pulled into violence not only as victims, but also as perpetrators. The involvement of children in war posses a severe challenge to prevailing moral and legal norms of the conduct of modern warfare. A major problem and most controversial issue, among others, is on the age at which children should be eligible to become combatants. Children, who may be viewed as a valuable resource due to their often inherent malleability, wish to avenge family member(s) killed in war, sense of immunity to danger, and or feeling of power in participating in the violence. Can the use of children as soldiers be effectively regulated in Africa? All efforts to assist child soldiers in recovering from the devastating effects of wars often unwillingly helped promote the growing number of child soldiers. This is in part because wars are now more fought internally among rebel armies and factions vying for power with the government and thus enlist children into their various armies. The study comes to a conclusion that drastic steps need to be taken to ameliorate this unfortunate situation. This formed the basis of the recommendations offered in the thesis to assist the African continent.
- Full Text:
- Date Issued: 2008
A comparative analysis of the use of participatory practices by indigenous trusts and mainstream development NGOs in Zvimba Communal Area Zimbabwe
- Authors: Mbanje, Bowden Bolt
- Date: 2020
- Subjects: Caritas Zimbabwe , Zvimba Community Share Ownership Trust (ZvCSOT) , Non-governmental organizations -- Zimbabwe -- Zvimba District , Community development -- Zimbabwe -- Zvimba District , Rural development -- Zimbabwe -- Zvimba District , Zvimba Communal Land (Zimbabwe)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167099 , vital:41437
- Description: This thesis compares the extent to which participatory practices have been used by Caritas Zimbabwe, a mainstream NGO, and the Zvimba Community Share Ownership Trust (ZvCSOT), an indigenous Trust, in Zvimba District, Zimbabwe. Participatory development initiatives are common practice in NGO and government development work in Zimbabwe. The thesis begins with a discussion of two aspects of participatory development (PD). Firstly, PD is discussed in relation to decentralization processes where central government transfers administrative and financial authority to sub-national government units in order to enhance the participation of rural communities in development interventions. Secondly, PD is discussed in relation to the increased role of NGOs in development work. During the 1980s and 1990s, shifts in development thinking resulted in NGOs being perceived as important actors who could attend to the development gaps left by an economically incapacitated state. Both NGOs and sub-national government units were seen to be closer to rural communities and so were thought to be in a better position to enhance the participation of these communities in meaningful development projects. An analysis of the practices of the NGO and CSOT under consideration in this study shows that while there has been much rhetorical commitment to participation, community participation in the development interventions of the NGO and the CSOT is inadequate. In introducing and implementing development interventions, there has been a tendency by both the NGO and CSOT to give priority to organizational preferences over local needs. While recognizing the participatory efforts made by mainstream development NGOs (Caritas in particular) and indigenous Trusts (Zvimba Community Share Ownership Trust in particular) in Zimbabwe, this thesis also considers the impact of other factors on participatory development initiatives. A major observation from the study is that in as much as we expect genuine participatory approaches which include grassroots communities’ inputs from the project’s conceptualization all the way to its evaluation, the challenge is that the elites at the higher level (central government and donor offices) have their own development preferences and interests while the elites at the lower levels (local government and NGO offices) also have their own priorities and needs. Consequently, local communities tend to be confined to implementing development projects foisted on them by elites at the higher level as well as those at the lower level. Worse still, the study shows that elites at the lowest level (community) sometimes hijack or take advantage of the imposed projects. Participation has been stalled by elites at various levels of the participatory development ladder. Thus, unless power imbalances are seriously addressed at all levels, participatory development will remain elusive.
- Full Text:
- Date Issued: 2020
- Authors: Mbanje, Bowden Bolt
- Date: 2020
- Subjects: Caritas Zimbabwe , Zvimba Community Share Ownership Trust (ZvCSOT) , Non-governmental organizations -- Zimbabwe -- Zvimba District , Community development -- Zimbabwe -- Zvimba District , Rural development -- Zimbabwe -- Zvimba District , Zvimba Communal Land (Zimbabwe)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167099 , vital:41437
- Description: This thesis compares the extent to which participatory practices have been used by Caritas Zimbabwe, a mainstream NGO, and the Zvimba Community Share Ownership Trust (ZvCSOT), an indigenous Trust, in Zvimba District, Zimbabwe. Participatory development initiatives are common practice in NGO and government development work in Zimbabwe. The thesis begins with a discussion of two aspects of participatory development (PD). Firstly, PD is discussed in relation to decentralization processes where central government transfers administrative and financial authority to sub-national government units in order to enhance the participation of rural communities in development interventions. Secondly, PD is discussed in relation to the increased role of NGOs in development work. During the 1980s and 1990s, shifts in development thinking resulted in NGOs being perceived as important actors who could attend to the development gaps left by an economically incapacitated state. Both NGOs and sub-national government units were seen to be closer to rural communities and so were thought to be in a better position to enhance the participation of these communities in meaningful development projects. An analysis of the practices of the NGO and CSOT under consideration in this study shows that while there has been much rhetorical commitment to participation, community participation in the development interventions of the NGO and the CSOT is inadequate. In introducing and implementing development interventions, there has been a tendency by both the NGO and CSOT to give priority to organizational preferences over local needs. While recognizing the participatory efforts made by mainstream development NGOs (Caritas in particular) and indigenous Trusts (Zvimba Community Share Ownership Trust in particular) in Zimbabwe, this thesis also considers the impact of other factors on participatory development initiatives. A major observation from the study is that in as much as we expect genuine participatory approaches which include grassroots communities’ inputs from the project’s conceptualization all the way to its evaluation, the challenge is that the elites at the higher level (central government and donor offices) have their own development preferences and interests while the elites at the lower levels (local government and NGO offices) also have their own priorities and needs. Consequently, local communities tend to be confined to implementing development projects foisted on them by elites at the higher level as well as those at the lower level. Worse still, the study shows that elites at the lowest level (community) sometimes hijack or take advantage of the imposed projects. Participation has been stalled by elites at various levels of the participatory development ladder. Thus, unless power imbalances are seriously addressed at all levels, participatory development will remain elusive.
- Full Text:
- Date Issued: 2020
A comparative exposition of Islamic law relating to the law of husband and wife
- Authors: Denson, Razaana
- Date: 2017
- Subjects: Husband and wife (Islamic law) Marriage (Islamic law)
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: http://hdl.handle.net/10948/19564 , vital:28894
- Description: Notwithstanding the enactment of the Constitution of the Republic of South Africa, 1996 the recognition of systems of religious, personal or family law for certain cultural and religious groups has either been limited or is virtually non-existent. To this extent, marriages concluded in terms of Islamic rites do not enjoy the same legal recognition that is accorded to civil and customary marriages. Non-recognition of Muslim marriages means there is no legal regulatory framework to enforce any of the consequences that arise as a result of the marriage, or any orders that are made by the Ulama, thereby creating a perilous situation that has dire consequences for spouses to a Muslim marriage. Despite South Africa’s commitment to the right of equality and freedom of religion, the courts have acknowledged that the failure to grant recognition to Muslim marriages on the ground of gender equality, has worsened the plight of women in these marriages, in that they were left without effective legal protection, should the union be dissolved either by death or divorce. Whilst the ad hoc recognition of certain consequences of Muslim marriages by the judiciary has gone a some way to redress the plight of Muslim women, and provided relief to the lived realities of Muslim women, these decisions are in fact contrary to the teachings and principles of Islam and therefore problematic for Muslims. These court decisions, that are in conflict with Muslim Personal Law (MPL), will ultimately lead to the emergence of a distorted set of laws relating to Muslim family law. This is a real cause for concern. This thesis is written from an Islamic legal theory perspective, which is contrary to western legal theory, as the latter adopts a human rights perspective. The basis of modern western democratic societies is a constitution that is premised on human rights and equality and which advocates the notion that the rights contained in the constitution reign supreme in all matters, religion included. Therefore, where a conflict arises in respect of the freedom of religion and the right to equality, western ideologies and philosophies dictate that the latter trump the former. This would inevitably mean that religious law would have to be adapted and ultimately amended so that it is in compliance with the constitution. From an Islamic religious perspective, this is not feasible and practicing Muslims will find this untenable. This may be legally uncomfortable in South Africa as a constitutional democracy but it is the reality for the adherents of the Muslim faith. A draft Muslim Marriages Bill (MMB) was released in 2003, and an amended MMB was tabled in Parliament in 2010. Both MMBs propose the legal recognition and regulation of Muslim marriages in South Africa. However, the two major issues delaying the enactment of the MMB into legislation are, firstly, whether or not the MMB would pass constitutional muster and secondly, the lack of agreement in the Muslim community on whether the MMB is Shari’ah compliant. Despite the largely consultative process that the MMBs underwent the legislative attempts to enact the MMB into legislation has not been successful. This thesis seeks to provide a possible solution whereby legislation regulating MPL law can be implemented in South Africa, notwithstanding the apparent conflict existing between MPL and the rights contained in the Bill of Rights. Notwithstanding the preference shown by the legislature to enact the MMB into legislation which will grant recognition to Muslim marriages, it is submitted there is a need for the legislature to rethink the approach that has to date been adopted. To this extent, it is submitted that the legislature should reconsider granting recognition to Muslim marriages by enacting legislation that takes the form of general legislation where state recognition is granted to all religious marriages, whether it be Muslim, Hindu or Jewish marriages. General legislation would mean that the state would require the marriage to be registered. However, the prescribed requirements, formalities and the consequences of the marriage would be determined by the chosen religious system of the spouses. On a national level a comparative analysis between Islamic law and the South African legal system, relating to the law of marriage is conducted. For the comparative analysis on an international level the law of marriage in England and Wales has been chosen. South Africa and England and Wales share a commitment to human rights and have adopted various approaches in respect of accommodating the application of Islamic law. Furthermore, an internal pluralism exists within the Muslim communities in South Africa, England and Wales as the majority of Muslims in these countries have to varying degrees developed diverse strategies to ensure compliance with Islamic law, and as well as South African and English law. The manner in which MPL is granted recognition needs to be given careful consideration as the implementation of this legislation will only be successful if it is compatible with the rulings and teachings of Islamic law. Caution should therefore be exercised to ensure that the fundamental aspects of MPL are not compromised as this will result in the legislation not being Shari’ah compliant and there will be no buyin from the Muslim community, with the consequence that this legislation will be mere paper law.
- Full Text:
- Date Issued: 2017
- Authors: Denson, Razaana
- Date: 2017
- Subjects: Husband and wife (Islamic law) Marriage (Islamic law)
- Language: English
- Type: Thesis , Doctoral , LLD
- Identifier: http://hdl.handle.net/10948/19564 , vital:28894
- Description: Notwithstanding the enactment of the Constitution of the Republic of South Africa, 1996 the recognition of systems of religious, personal or family law for certain cultural and religious groups has either been limited or is virtually non-existent. To this extent, marriages concluded in terms of Islamic rites do not enjoy the same legal recognition that is accorded to civil and customary marriages. Non-recognition of Muslim marriages means there is no legal regulatory framework to enforce any of the consequences that arise as a result of the marriage, or any orders that are made by the Ulama, thereby creating a perilous situation that has dire consequences for spouses to a Muslim marriage. Despite South Africa’s commitment to the right of equality and freedom of religion, the courts have acknowledged that the failure to grant recognition to Muslim marriages on the ground of gender equality, has worsened the plight of women in these marriages, in that they were left without effective legal protection, should the union be dissolved either by death or divorce. Whilst the ad hoc recognition of certain consequences of Muslim marriages by the judiciary has gone a some way to redress the plight of Muslim women, and provided relief to the lived realities of Muslim women, these decisions are in fact contrary to the teachings and principles of Islam and therefore problematic for Muslims. These court decisions, that are in conflict with Muslim Personal Law (MPL), will ultimately lead to the emergence of a distorted set of laws relating to Muslim family law. This is a real cause for concern. This thesis is written from an Islamic legal theory perspective, which is contrary to western legal theory, as the latter adopts a human rights perspective. The basis of modern western democratic societies is a constitution that is premised on human rights and equality and which advocates the notion that the rights contained in the constitution reign supreme in all matters, religion included. Therefore, where a conflict arises in respect of the freedom of religion and the right to equality, western ideologies and philosophies dictate that the latter trump the former. This would inevitably mean that religious law would have to be adapted and ultimately amended so that it is in compliance with the constitution. From an Islamic religious perspective, this is not feasible and practicing Muslims will find this untenable. This may be legally uncomfortable in South Africa as a constitutional democracy but it is the reality for the adherents of the Muslim faith. A draft Muslim Marriages Bill (MMB) was released in 2003, and an amended MMB was tabled in Parliament in 2010. Both MMBs propose the legal recognition and regulation of Muslim marriages in South Africa. However, the two major issues delaying the enactment of the MMB into legislation are, firstly, whether or not the MMB would pass constitutional muster and secondly, the lack of agreement in the Muslim community on whether the MMB is Shari’ah compliant. Despite the largely consultative process that the MMBs underwent the legislative attempts to enact the MMB into legislation has not been successful. This thesis seeks to provide a possible solution whereby legislation regulating MPL law can be implemented in South Africa, notwithstanding the apparent conflict existing between MPL and the rights contained in the Bill of Rights. Notwithstanding the preference shown by the legislature to enact the MMB into legislation which will grant recognition to Muslim marriages, it is submitted there is a need for the legislature to rethink the approach that has to date been adopted. To this extent, it is submitted that the legislature should reconsider granting recognition to Muslim marriages by enacting legislation that takes the form of general legislation where state recognition is granted to all religious marriages, whether it be Muslim, Hindu or Jewish marriages. General legislation would mean that the state would require the marriage to be registered. However, the prescribed requirements, formalities and the consequences of the marriage would be determined by the chosen religious system of the spouses. On a national level a comparative analysis between Islamic law and the South African legal system, relating to the law of marriage is conducted. For the comparative analysis on an international level the law of marriage in England and Wales has been chosen. South Africa and England and Wales share a commitment to human rights and have adopted various approaches in respect of accommodating the application of Islamic law. Furthermore, an internal pluralism exists within the Muslim communities in South Africa, England and Wales as the majority of Muslims in these countries have to varying degrees developed diverse strategies to ensure compliance with Islamic law, and as well as South African and English law. The manner in which MPL is granted recognition needs to be given careful consideration as the implementation of this legislation will only be successful if it is compatible with the rulings and teachings of Islamic law. Caution should therefore be exercised to ensure that the fundamental aspects of MPL are not compromised as this will result in the legislation not being Shari’ah compliant and there will be no buyin from the Muslim community, with the consequence that this legislation will be mere paper law.
- Full Text:
- Date Issued: 2017
A comparative polarimetric study of the 43 GHz and 86 GHz SiO masers toward the supergiant star VY CMa
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
- Date Issued: 2012
- Authors: Richter, Laura
- Date: 2012
- Subjects: Masers Supergiant stars Polarization (Light) Very long baseline interferometry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5454 , http://hdl.handle.net/10962/d1005239
- Description: The aim of this thesis is to perform observational tests of SiO maser polarisation and excitation models, using component-level comparisons of multiple SiO maser transitions in the 43 GHz and 86 GHz bands at milliarcsecond resolution. These observations reqwre very long baseline interferometric imaging with very accurate polarimetric calibration. The supergiant star VY CMa was chosen as the object of this study due to its high SiO maser luminosity, many detected SiO maser lines, and intrinsic scientific interest. Two epochs of full-polarisation VLBA observations of VY CMa were performed. The Epoch 2 observations were reduced using several new data reduction methods developed as part of this work, and designed specifically to improve the accuracy of circular polarisation calibration of spectral-line VLBI observations at millimetre wavelengths. The accuracy is estimated to be better than 1% using these methods. The Epoch 2 images show a concentration of v= l and v=2 J= 1-0 SiO masers to the east and northeast of the assumed stellar position. The v=l J=2-1 masers were more evenly distributed around the star, with a notable lack of emission in the northeast. There is appreciable spatial overlap between these three lines. The nature of the overlap is generally consistent with the predictions of hydrodynamical circumstellar SiO maser simulations. Where the v=l J = 1-0 and J =2-1 features overlap, the v=l J = 2-1 emission is usually considerably weaker. This is not predicted by current hydrodynamical models, but can be explained in the context of collisional pumping in a low density environment. Six observational tests of weak-splitting maser polarisation models were performed, including intercomparisons of linear polarisation in the v=l J=1-0 and J=2-1lines, linear polarisation versus saturation level, linear polarisation versus distance from the star, circular polarisation in the v= l J = 1-0 and J=2-1 lines, circular versus linear polarisation and modeling of ~ 900 electric-vector position angle rotations. The polarisation model tests generally do not support non-Zeeman circular polarisation mechanisms. For the linear polarisation tests, the results are more consistent with models that predict similar linear polarisation across transitions. The scientific importance of these tests is described in detail and avenues for future work are described.
- Full Text:
- Date Issued: 2012
A comparative study of artificial neural networks and physics models as simulators in evolutionary robotics
- Pretorius, Christiaan Johannes
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
A comparative study of atmospheric dynamics in the mesosphere and lower thermosphere (MLT) near Grahamstown (South Africa) and Adelaide (Australia)
- Authors: Malinga, Sandile Bethuel
- Date: 2002
- Subjects: Atmospheric physics Atmospheric physics -- South Africa -- Eastern Cape Atmospheric physics -- Australia Dynamic meteorology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5506 , http://hdl.handle.net/10962/d1007307
- Description: The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.
- Full Text:
- Date Issued: 2002
- Authors: Malinga, Sandile Bethuel
- Date: 2002
- Subjects: Atmospheric physics Atmospheric physics -- South Africa -- Eastern Cape Atmospheric physics -- Australia Dynamic meteorology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5506 , http://hdl.handle.net/10962/d1007307
- Description: The observations made near Grahamstown (33 .3°S, 26.5°E), South Africa and Adelaide (34.5°S, 138.5°E), Australia over the years 1987 to 1994 are used to study the dynamics of the mesosphere and lower thermosphere (ML T) region with a focus on ∼ 90 km altitude. In particular this thesis deals with on the atmospheric mean flow and the solar diurnal and semi diurnal oscillations with a view to (i) deducing their patterns at the two sites, (ii) comparing the dynamic structures observed at the two sites with special emphases on longitudinal variations, and (iii) putting these observations in a global context by comparing with other ground-based observations, satellite observations and numerical simulations. The main findings are summarised below. The mean flow and the tides at Grahamstown and Adelaide are characteristically variable at planetary time scales. Wavelet spectral and multiresolution analyses reveal that the dominant planetary oscillation is the quasi-16-day oscillation. However, no apparent correlation in the 16-day waves of the mean flow, the diurnal tide and the semidiurnal tide was found. The short-term fluctuations were also investigated using complex demodulation and bispectral techniques and it was found that some of the observed variations in tides could be due to non-linear wave-wave interactions. The long-term trends of the mean flow and tides show patterns that are in broad agreement with theory, results from elsewhere (ground-based and satellite) and the results of the Global-Scale Wave Model and various models by Portnyagin and others. In general the mean flow, the amplitudes and phases of both tides were found to exhibit seasonal and interannual variations which are thought to be related to various factors including (i) changes in the atmospheric mean environment, (ii) thermotidal forcing (iii) gravity wave effects, (iv) planetary scale influence, (v) long-term (e.g. quasi-biennial oscillation) modulation, and (vi) solar activity. There are significant longitudinal differences in the dynamic structure between Grahamstown and Adelaide. More especially, Grahamstown tends to have stronger mean flow and tidal activity than Adelaide. For tides, these differences are thought to be partly due to nonmigrating tidal modes but, in general, migrating modes were found to be dominant.
- Full Text:
- Date Issued: 2002