Legal remedies against corruption: lessons from Guatemala
- Cordell, Cameron George Thomas
- Authors: Cordell, Cameron George Thomas
- Date: 2019
- Subjects: Remedies (Law) -- Guatemala , Remedies (Law) -- South Africa Criminal law -- Guatemala Criminal law -- South Africa Public law -- South Africa Public law -- Guatemala
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/38013 , vital:34281
- Description: Corruption is a crime which has affected all levels of government in South Africa. Despite the multi-agency system developed since the advent of democracy, levels of corruption are still on the rise, with greater levels of impunity. It is clear that reform is needed within South Africa’s anti-corruption framework. The state of Guatemala has meanwhile achieved results that have been described as transcendental in the fight against corruption, via a novel anti-corruption commission formed in collaboration with the United Nations, known as the Commission against Impunity in Guatemala (CICIG). This dissertation begins with an examination of the content of the crime of corruption via a historical approach – charting the course of corruption and effort to curb it from Ancient Greece, Mesoamerica and Africa, through the various legal systems that have resulted in the modern-day legal frameworks of South Africa and Guatemala. In doing so, a working definition of corruption has been developed – namely the unlawful and unethical enrichment of the self at the expense of the state. This definition aids in clearly defining proven instances of corruption within the public sector in modern South Africa. While corruption as a crime is generally clandestine in nature and difficult to deal with quantitatively, it is clearly demonstrated from the instances of corruption that have been proven that the offence is dealt with ineffectually by the existing policy and legal framework. Examinations of corruption scandals such as the capture of the state by private family corporations, to the collapse of South Africa’s Social Security Agency (SASSA), show that even when proven, corrupt politicians rarely face consequences for their actions. This is due to the lack of clarity in the primary legislation dealing with corruption – the Prevention and Combatting of Corrupt Activity Act (PRECCA), combined with a multi-agency approach wherein the various bodies tasked with combatting corruption are not working cohesively. The solution to this problem is a single commission to integrate the anti-corruption framework, as well as providing a fresh perspective about how to deal with the crime. The CICIG has served this role in Guatemala, resulting in successful investigations and prosecutions of former Presidents, judges and members of the legislature. It has achieved this by supporting and working with the existing anti-corruption bodies, as well as advising government on effective policy reform. It is further staffed by anti-corruption experts who are from the Central and South American region, providing a level of trust and regional knowledge. There is no bar in South African law for the creation of a similar international body. Such a move is necessary to provide a fresh outlook on the fight against corruption in South Africa. An international body, staffed by African anti-corruption experts, would be an effective means to work with the multi-agency system currently in place to aid it in working cohesively, but also to provide African solutions to the scourge of corruption through policy reform.
- Full Text:
- Date Issued: 2019
- Authors: Cordell, Cameron George Thomas
- Date: 2019
- Subjects: Remedies (Law) -- Guatemala , Remedies (Law) -- South Africa Criminal law -- Guatemala Criminal law -- South Africa Public law -- South Africa Public law -- Guatemala
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: http://hdl.handle.net/10948/38013 , vital:34281
- Description: Corruption is a crime which has affected all levels of government in South Africa. Despite the multi-agency system developed since the advent of democracy, levels of corruption are still on the rise, with greater levels of impunity. It is clear that reform is needed within South Africa’s anti-corruption framework. The state of Guatemala has meanwhile achieved results that have been described as transcendental in the fight against corruption, via a novel anti-corruption commission formed in collaboration with the United Nations, known as the Commission against Impunity in Guatemala (CICIG). This dissertation begins with an examination of the content of the crime of corruption via a historical approach – charting the course of corruption and effort to curb it from Ancient Greece, Mesoamerica and Africa, through the various legal systems that have resulted in the modern-day legal frameworks of South Africa and Guatemala. In doing so, a working definition of corruption has been developed – namely the unlawful and unethical enrichment of the self at the expense of the state. This definition aids in clearly defining proven instances of corruption within the public sector in modern South Africa. While corruption as a crime is generally clandestine in nature and difficult to deal with quantitatively, it is clearly demonstrated from the instances of corruption that have been proven that the offence is dealt with ineffectually by the existing policy and legal framework. Examinations of corruption scandals such as the capture of the state by private family corporations, to the collapse of South Africa’s Social Security Agency (SASSA), show that even when proven, corrupt politicians rarely face consequences for their actions. This is due to the lack of clarity in the primary legislation dealing with corruption – the Prevention and Combatting of Corrupt Activity Act (PRECCA), combined with a multi-agency approach wherein the various bodies tasked with combatting corruption are not working cohesively. The solution to this problem is a single commission to integrate the anti-corruption framework, as well as providing a fresh perspective about how to deal with the crime. The CICIG has served this role in Guatemala, resulting in successful investigations and prosecutions of former Presidents, judges and members of the legislature. It has achieved this by supporting and working with the existing anti-corruption bodies, as well as advising government on effective policy reform. It is further staffed by anti-corruption experts who are from the Central and South American region, providing a level of trust and regional knowledge. There is no bar in South African law for the creation of a similar international body. Such a move is necessary to provide a fresh outlook on the fight against corruption in South Africa. An international body, staffed by African anti-corruption experts, would be an effective means to work with the multi-agency system currently in place to aid it in working cohesively, but also to provide African solutions to the scourge of corruption through policy reform.
- Full Text:
- Date Issued: 2019
Factors influencing employee participation in employee health and wellness programmes : the case of Mdantsane Police Station
- Kwayiba, Nthabiseng Justinah
- Authors: Kwayiba, Nthabiseng Justinah
- Date: 2018
- Subjects: Employee assistance programs Health behavior Motivation (Psychology)
- Language: English
- Type: Thesis , Masters , Social Work
- Identifier: http://hdl.handle.net/10353/17127 , vital:40858
- Description: The purpose of the study was to determine the factors influencing participation in Employee Health and Wellness programmes rendered by South African Police Service. Qualitative method was used and case study design was chosen. Data was collected from twenty-two participants. Semi structured interviews was used as an instrument to collect data. Interpretivism paradigm was followed for data analysis. The findings of this study revealed that participation in EHW Programmes is indeed low at Mdantsane Accountable Police Station. Most of the participants did not show any interest in the services rendered by SAPS. Their belief systems and perceptions about EHW Programs are a contributing factor to the non-utilisation of the services. One major factor that was identified by this research was the impact police training has on the decisions police members make to participate or not to participate in EHW Programmes. SAPS is a male dominated organisation, with employees that are rooted in cultural beliefs. Some participants, especially men mentioned that it is against their culture to talk about their personal problems to strangers, referring to EHW Professionals, others believed that seeking professional help from a female professional is a sign of losing your manhood an indication that you are weak. With this kind of personal belief, the researcher is of the view that SAPS has to consider adopting a new EHW Model, a model that will be relevant to the objectives of SAPS. Engaging police officers in physical activities will be more effective in promoting participation because Police work requires that police members need more than just task competencies or technical knowledge to do their work (Turner, 2014), they need to be physically fit in order to protect themselves and the community they are serving. Engaging them in counselling and educational programmes will not increase participation since they regard such services to be meant for the weak police officers.
- Full Text:
- Date Issued: 2018
- Authors: Kwayiba, Nthabiseng Justinah
- Date: 2018
- Subjects: Employee assistance programs Health behavior Motivation (Psychology)
- Language: English
- Type: Thesis , Masters , Social Work
- Identifier: http://hdl.handle.net/10353/17127 , vital:40858
- Description: The purpose of the study was to determine the factors influencing participation in Employee Health and Wellness programmes rendered by South African Police Service. Qualitative method was used and case study design was chosen. Data was collected from twenty-two participants. Semi structured interviews was used as an instrument to collect data. Interpretivism paradigm was followed for data analysis. The findings of this study revealed that participation in EHW Programmes is indeed low at Mdantsane Accountable Police Station. Most of the participants did not show any interest in the services rendered by SAPS. Their belief systems and perceptions about EHW Programs are a contributing factor to the non-utilisation of the services. One major factor that was identified by this research was the impact police training has on the decisions police members make to participate or not to participate in EHW Programmes. SAPS is a male dominated organisation, with employees that are rooted in cultural beliefs. Some participants, especially men mentioned that it is against their culture to talk about their personal problems to strangers, referring to EHW Professionals, others believed that seeking professional help from a female professional is a sign of losing your manhood an indication that you are weak. With this kind of personal belief, the researcher is of the view that SAPS has to consider adopting a new EHW Model, a model that will be relevant to the objectives of SAPS. Engaging police officers in physical activities will be more effective in promoting participation because Police work requires that police members need more than just task competencies or technical knowledge to do their work (Turner, 2014), they need to be physically fit in order to protect themselves and the community they are serving. Engaging them in counselling and educational programmes will not increase participation since they regard such services to be meant for the weak police officers.
- Full Text:
- Date Issued: 2018
A critical analysis of housing provision, livelihood activities and social reproduction in urban communities in South Africa: the case of Ezamokuhle, Mpumalanga
- Authors: Nkambule, Sipho Jonathan
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7788 , vital:21298
- Description: The post-apartheid South African state has formulated, introduced and implemented nationwide policies and programmes pertaining to urban housing in order to address and tackle the challenges of social reproduction in and for poor urban black communities. This however has been undermined for a number of reasons, such as state incapacities and the state’s neo-liberal overreliance on the market to remedy past injustices. At the same time households, as critical sites of social reproduction in poor urban black communities and under conditions of extreme vulnerability, engage in a range of productive and non-productive activities often in a desperate bid to construct and maintain a semblance of livelihood sustainability. The thesis seeks to critically understand the relationship between state housing programmes and the diverse livelihood activities of poor urban black households in South Africa in the context of an ongoing systemic crisis of social reproduction which exists in these urban communities. This is pursued with specific reference to eZamokuhle Township in Amersfoort, Mpumalanga Province. The thesis is framed conceptually in terms of the notion of social reproduction. In doing so, it brings together two sets of literature which are often disconnected. On the one hand, there is South African literature which critically analyses the post-apartheid state’s housing programmes including the many challenges which exist in this regard. On the other hand, there is literature which considers the urban livelihoods of poor black communities in contemporary South Africa and often from within some kind of livelihoods perspective. The thesis is innovative in bringing these two sets of literature together in terms of the overarching notion of social reproduction and providing, therefore, a more holistic and integrated understanding of the multi-dimensional character of social reproduction. The depth of the crisis of social reproduction in eZamokuhle is explicated and examined in this way but in a manner which articulates the lived experiences and agency of eZamokhule households despite vulnerability constraints and challenges.
- Full Text:
- Date Issued: 2017
- Authors: Nkambule, Sipho Jonathan
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7788 , vital:21298
- Description: The post-apartheid South African state has formulated, introduced and implemented nationwide policies and programmes pertaining to urban housing in order to address and tackle the challenges of social reproduction in and for poor urban black communities. This however has been undermined for a number of reasons, such as state incapacities and the state’s neo-liberal overreliance on the market to remedy past injustices. At the same time households, as critical sites of social reproduction in poor urban black communities and under conditions of extreme vulnerability, engage in a range of productive and non-productive activities often in a desperate bid to construct and maintain a semblance of livelihood sustainability. The thesis seeks to critically understand the relationship between state housing programmes and the diverse livelihood activities of poor urban black households in South Africa in the context of an ongoing systemic crisis of social reproduction which exists in these urban communities. This is pursued with specific reference to eZamokuhle Township in Amersfoort, Mpumalanga Province. The thesis is framed conceptually in terms of the notion of social reproduction. In doing so, it brings together two sets of literature which are often disconnected. On the one hand, there is South African literature which critically analyses the post-apartheid state’s housing programmes including the many challenges which exist in this regard. On the other hand, there is literature which considers the urban livelihoods of poor black communities in contemporary South Africa and often from within some kind of livelihoods perspective. The thesis is innovative in bringing these two sets of literature together in terms of the overarching notion of social reproduction and providing, therefore, a more holistic and integrated understanding of the multi-dimensional character of social reproduction. The depth of the crisis of social reproduction in eZamokuhle is explicated and examined in this way but in a manner which articulates the lived experiences and agency of eZamokhule households despite vulnerability constraints and challenges.
- Full Text:
- Date Issued: 2017
The design and testing of a national estuarine monitoring prgramme for South Africa
- Authors: Cilliers, Gerhard Jordaan
- Date: 2017
- Subjects: Estuaries -- South Africa Berg Estuary (South Africa)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/15490 , vital:28258
- Description: Adaptive water resource management requires sound scientific based decisions, emanating from robust scientific data. The Department of Environmental Affairs are mandated for collaborative management of the South African coast, including estuaries, through the Integrated Coastal Management Act (Act no 24 of 2008) (ICMA). The Department Water and Sanitation is mandated through the National Water Act (Act no 36 of 1998) (NWA) to design, test and implement monitoring programmes to provide water resource data. Extensive freshwater monitoring programmes exist in South Africa but there is no standard long-term monitoring programme for estuaries. This study designed and tested a National Estuarine Monitoring Programme (NESMP) that is anchored in the NWA and the ICMA. The design was based on a review of international estuary monitoring programmes, consultation with relevant role players and five decades experience in the design, testing and implementation of water resource monitoring programmes by DWS. The main objective of this thesis is 1) to design a national estuarine monitoring programme 2) test the design of the programme for practical implementation by reflecting on collected data from case studies, and 3) design a Decision Support System to translate complex monitoring data into management information. The main objective of the NESMP is 1) to collect long-term data to determine trends in the condition of estuaries in South Africa and 2) to provide management orientated information for effective estuary management. The National Estuary Monitoring programme consists of three tiers. Tier 1 focuses on basic data including system variables and nutrient data. Tier 2 collects data required for the determination of the Ecological Water Requirements (EWR) of estuaries in accordance with a standardised method used by DWS. A tailor made monitoring programme addressing specific issues including pollution incidents and localised development pressure, making use of a combination of Tier 1 and Tier 2 components, forms Tier 3 of the NESMP. This study tested the Tier 1 components of the programme on 28 estuaries across the South African coast since 2012. However, due to space constraints, the data reflected on in this thesis, is only for case studies on the Berg and Breede estuaries between 2012 and 2016. The results indicate that the establishment and operation of the NESMP on South African estuaries making use of monthly surveys, and the deployment of permanent water quality loggers, in line with the proposed protocol, are possible. This does however require collaboration with other role players in order to share responsibility and associated resources. A tiered management structure ensures national, regional and local level implementation takes place seamlessly. A decision support system (DSS) was also designed as part of this thesis to assist with data interpretation and the creation of management orientated information. This DSS includes a measurement of the percentage exceedance of the Threshold of Potential Concern (TPC), which acts as an early warning system for water resource deterioration. This study showed that effective collaboration will ensure the sustainability of the NESMP. Implementation of the more complex and resource intensive Tier 2 and Tier 3 sampling will however need to be investigated to establish the overall success of the NESMP.
- Full Text:
- Date Issued: 2017
- Authors: Cilliers, Gerhard Jordaan
- Date: 2017
- Subjects: Estuaries -- South Africa Berg Estuary (South Africa)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/15490 , vital:28258
- Description: Adaptive water resource management requires sound scientific based decisions, emanating from robust scientific data. The Department of Environmental Affairs are mandated for collaborative management of the South African coast, including estuaries, through the Integrated Coastal Management Act (Act no 24 of 2008) (ICMA). The Department Water and Sanitation is mandated through the National Water Act (Act no 36 of 1998) (NWA) to design, test and implement monitoring programmes to provide water resource data. Extensive freshwater monitoring programmes exist in South Africa but there is no standard long-term monitoring programme for estuaries. This study designed and tested a National Estuarine Monitoring Programme (NESMP) that is anchored in the NWA and the ICMA. The design was based on a review of international estuary monitoring programmes, consultation with relevant role players and five decades experience in the design, testing and implementation of water resource monitoring programmes by DWS. The main objective of this thesis is 1) to design a national estuarine monitoring programme 2) test the design of the programme for practical implementation by reflecting on collected data from case studies, and 3) design a Decision Support System to translate complex monitoring data into management information. The main objective of the NESMP is 1) to collect long-term data to determine trends in the condition of estuaries in South Africa and 2) to provide management orientated information for effective estuary management. The National Estuary Monitoring programme consists of three tiers. Tier 1 focuses on basic data including system variables and nutrient data. Tier 2 collects data required for the determination of the Ecological Water Requirements (EWR) of estuaries in accordance with a standardised method used by DWS. A tailor made monitoring programme addressing specific issues including pollution incidents and localised development pressure, making use of a combination of Tier 1 and Tier 2 components, forms Tier 3 of the NESMP. This study tested the Tier 1 components of the programme on 28 estuaries across the South African coast since 2012. However, due to space constraints, the data reflected on in this thesis, is only for case studies on the Berg and Breede estuaries between 2012 and 2016. The results indicate that the establishment and operation of the NESMP on South African estuaries making use of monthly surveys, and the deployment of permanent water quality loggers, in line with the proposed protocol, are possible. This does however require collaboration with other role players in order to share responsibility and associated resources. A tiered management structure ensures national, regional and local level implementation takes place seamlessly. A decision support system (DSS) was also designed as part of this thesis to assist with data interpretation and the creation of management orientated information. This DSS includes a measurement of the percentage exceedance of the Threshold of Potential Concern (TPC), which acts as an early warning system for water resource deterioration. This study showed that effective collaboration will ensure the sustainability of the NESMP. Implementation of the more complex and resource intensive Tier 2 and Tier 3 sampling will however need to be investigated to establish the overall success of the NESMP.
- Full Text:
- Date Issued: 2017
Mechanism and synchronicity of wheat (Triticum aestivum) resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1
- Authors: Njom, Henry Akum
- Date: 2016
- Subjects: Wheat -- Disease and pest resistance Bacterial diseases of plants Russian wheat aphid
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2700 , vital:28056
- Description: Wheat (Triticum aestivum and T. Durum) is an extremely important agronomic crop produced worldwide. Wheat consumption has doubled in the last 30 years with approximately 600 million tons consumed per annum. According to the International Maize and Wheat Improvement Center, worldwide wheat demand will increase over 40 percent by 2020, while land as well as resources available for the production will decrease significantly if the current trend prevails. The wheat industry is challenged with abiotic and biotic stressors that lead to reduction in crop yields. Increase knowledge of wheat’s biochemical constitution and functional biology is of paramount importance to improve wheat so as to meet with this demand. Pesticides and fungicides are being used to control biotic stress imposed by insect pest and fungi pathogens but these chemicals pose a risk to the environment and human health. To this effect, there is re-evaluation of pesticides currently in use by the Environmental Protection Agency, via mandates of the 1996 Food Quality Protection Act and those with higher perceived risks are banned. Genetic resistance is now a more environmental friendly and effective method of controlling insect pest and rust diseases of wheat than the costly spraying with pesticides and fungicides. Although, resistant cultivars effectively prevent current prevailing pathotypes of leaf rust and biotypes of Russian wheat aphid from attacking wheat, new pathotypes and biotypes of the pathogen/pest may develop and infect resistant cultivars. Therefore, breeders are continually searching for new sources of resistance. Proteomic approaches can be utilised to ascertain target enzymes and proteins from resistant lines that could be utilised to augment the natural tolerance of agronomically favourable varieties of wheat. With this ultimate goal in mind, the aim of this study was to elucidate the mechanism and synchronicity of wheat resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1. To determine the resistance mechanism of the wheat cultivars to leaf rust infection and Russian wheat aphid infestation, a proteomics approach using two-dimensional gel electrophoresis was used in order to determine the effect of RWA SA1 on the wheat cultivars proteome. Differentially expressed proteins that were up or down regulated (appearing or disappearing) were identified using PDQuestTM Basic 2-DE Gel analysis software. Proteins bands of interest were in-gel trypsin digested as per the protocol described in Schevchenko et al. (2007) and analysed using a Dionex Ultimate 3000 RSLC system coupled to an AB Sciex 6600 TripleTOF mass spectrometer. Protein pilot v5 using Paragon search engine (AB Sciex) was used for comparison of the obtained MS/MS spectra with a custom database containing sequences of Puccinia triticina (Uniprot Swissprot), Triticum aestivum (Uniprot TrEMBL) and Russian wheat aphid (Uniprot TrEMBL) as well as a list of sequences from common contaminating proteins. Proteins with a threshold of ≥99.9 percent confidence were reported. A total of 72 proteins were putatively identified from the 37 protein spots excised originating from either leaf rust or Russian wheat aphid experiments. Sixty-three of these proteins were associated with wheat response to stress imposed by RWA SA1 feeding while 39 were associated with infection by Puccinia triticina. Several enzymes involved in the Calvin cycle, electron transport and ATP synthesis were observed to be differentially regulated suggesting greater metabolic requirements in the wheat plants following aphid infestation and leaf rust infection. Proteins directly associated with photosynthesis were also differentially regulated following RWA SA1 infestation and P.
- Full Text:
- Date Issued: 2016
- Authors: Njom, Henry Akum
- Date: 2016
- Subjects: Wheat -- Disease and pest resistance Bacterial diseases of plants Russian wheat aphid
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/2700 , vital:28056
- Description: Wheat (Triticum aestivum and T. Durum) is an extremely important agronomic crop produced worldwide. Wheat consumption has doubled in the last 30 years with approximately 600 million tons consumed per annum. According to the International Maize and Wheat Improvement Center, worldwide wheat demand will increase over 40 percent by 2020, while land as well as resources available for the production will decrease significantly if the current trend prevails. The wheat industry is challenged with abiotic and biotic stressors that lead to reduction in crop yields. Increase knowledge of wheat’s biochemical constitution and functional biology is of paramount importance to improve wheat so as to meet with this demand. Pesticides and fungicides are being used to control biotic stress imposed by insect pest and fungi pathogens but these chemicals pose a risk to the environment and human health. To this effect, there is re-evaluation of pesticides currently in use by the Environmental Protection Agency, via mandates of the 1996 Food Quality Protection Act and those with higher perceived risks are banned. Genetic resistance is now a more environmental friendly and effective method of controlling insect pest and rust diseases of wheat than the costly spraying with pesticides and fungicides. Although, resistant cultivars effectively prevent current prevailing pathotypes of leaf rust and biotypes of Russian wheat aphid from attacking wheat, new pathotypes and biotypes of the pathogen/pest may develop and infect resistant cultivars. Therefore, breeders are continually searching for new sources of resistance. Proteomic approaches can be utilised to ascertain target enzymes and proteins from resistant lines that could be utilised to augment the natural tolerance of agronomically favourable varieties of wheat. With this ultimate goal in mind, the aim of this study was to elucidate the mechanism and synchronicity of wheat resistance to leaf rust (Puccinia triticina) and Russian wheat aphid (Duiraphis noxia) SA1. To determine the resistance mechanism of the wheat cultivars to leaf rust infection and Russian wheat aphid infestation, a proteomics approach using two-dimensional gel electrophoresis was used in order to determine the effect of RWA SA1 on the wheat cultivars proteome. Differentially expressed proteins that were up or down regulated (appearing or disappearing) were identified using PDQuestTM Basic 2-DE Gel analysis software. Proteins bands of interest were in-gel trypsin digested as per the protocol described in Schevchenko et al. (2007) and analysed using a Dionex Ultimate 3000 RSLC system coupled to an AB Sciex 6600 TripleTOF mass spectrometer. Protein pilot v5 using Paragon search engine (AB Sciex) was used for comparison of the obtained MS/MS spectra with a custom database containing sequences of Puccinia triticina (Uniprot Swissprot), Triticum aestivum (Uniprot TrEMBL) and Russian wheat aphid (Uniprot TrEMBL) as well as a list of sequences from common contaminating proteins. Proteins with a threshold of ≥99.9 percent confidence were reported. A total of 72 proteins were putatively identified from the 37 protein spots excised originating from either leaf rust or Russian wheat aphid experiments. Sixty-three of these proteins were associated with wheat response to stress imposed by RWA SA1 feeding while 39 were associated with infection by Puccinia triticina. Several enzymes involved in the Calvin cycle, electron transport and ATP synthesis were observed to be differentially regulated suggesting greater metabolic requirements in the wheat plants following aphid infestation and leaf rust infection. Proteins directly associated with photosynthesis were also differentially regulated following RWA SA1 infestation and P.
- Full Text:
- Date Issued: 2016
Structural, optical and electrical characterization of nano-sized c-tio2 quamtum dots synthesized by spray pyrolysis
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
- Authors: Taziwa, Raymond Tichaona
- Date: 2014
- Language: English
- Type: Thesis , Doctoral , PhD (Chemistry)
- Identifier: vital:11342 , http://hdl.handle.net/10353/d1016089
- Description: In the 21st century, scientific communities face challenges and opportunities concerning future development, where innovations must be a key driver over the past, evolution of African societies were based on incomplete models, only taking into account economical growth and not paying attention to environmental deterioration as a consequence of anthropogenic activity and environmental pollution. We have to learn from our past mistakes in order not to repeat them. Education and research of today as the embryonic stages of the development models of tomorrow should be directed toward a sustainable mentality. In this sense, solar energy technologies have emerged as key instruments for minimizing environmental impact as well as reducing economic cost in the field of renewable energies. Titanium dioxide is a fascinating low cost material exhibiting unique properties of stability and photo catalytic activities, leading to clean technologies in water purification and energy conversion of sunlight. However, conventional techniques (high temperature, high vacuum, high pressures) of processing titanium dioxide are a technological limitation due to excessive energy consumption. This poses a handicap for practical applications in areas such as preparation of hybrid organic/Titanium dioxide materials or devices on thermo flexible substrates such as plastic material. It is for this reason that the investigation presented in this Ph.D thesis deals with the development of spray pyrolysis techniques for preparation of carbon doped titanium dioxide nano powders for solar cell applications. This thesis is therefore structured as follows: Chapter 1 gives a general overview of the work done in this thesis. This work relies greatly on the excellent structural optical and electrical properties of TiO2 thin films, as well as its chemical resistance and insulating properties. A summary of the physical, optical, electrical and chemical properties reported in the literature, with an emphasis on those relevant to solar cell fabrication, is presented in Chapter 2. Chapter 3 gives a concise literature review on models governing droplet formation in ultrasonic spray pyrolysis (USP) techniques, the limitations of these models have been exposed and a new relation model for estimating the final particle size given a set of initial reaction conditions has been proposed. The presently derived model is quite advantageous in that it does not require the investigator to look up values of surface tension and density for every precursor solution. Chapter 4 presents in detail the designed and constructed spray pyrolysis system capable of realizing desired nano structures for photovoltaic applications. The first system employed an ultrasonic atomization spray nozzle in order to create an aerosol of the TiO2 precursor. The reasons for choosing ultrasonic spray deposition (USP) and the TiO2 precursors, titanium iso propoxide and titanium tetra butoxide are discussed. Chapter 5 outlines experimental methodologies used in synthesis and characterization of the materials used in this study. Chapter 5 further provides experimental methodologies used in fabrication of a new type of photo electrochemical solar cells (PECs). Chapter 6 reveals the opto-electrical results of PECs solar cells fabricated. There are numerous properties that are affected by the size but emphasis will be placed on nano-size and confinement effects. Chapter 7 presents a confirmation of the phonon confinement effects in C-TiO2 QDs for the first time. In addition Chapter 7 also presents a new phonon confinement model. Chapter 8 reveals the optical, structural and electronic properties of C-TiO2 QDs synthesized by USP and PSP techniques. In addition the electrical properties of C-TiO2 QDs PEC solar cells devices are reported in Chapter 8. Concluding remarks, with potential future research projects are presented in Chapter 9. Through these 9 chapters, all research questions have been answered satisfactorily and all objectives met. Most of the work contained in this thesis has been subjected to external reviews through publication of these peer reviewed articles.
- Full Text:
- Date Issued: 2014
Understanding the harm of rape
- Authors: Kelland, Lindsay-Ann
- Date: 2013-04-19
- Subjects: Rape -- Social aspects--Research -- South Africa Rape -- Psychological aspects -- Research -- South Africa Rape trauma syndrome -- Research -- South Africa Rape victims -- South Africa Patriarchy -- South Africa Sexual dominance and submission -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2700 , http://hdl.handle.net/10962/d1001582
- Description: The aims of this thesis are twofold: to provide an account of the lived experience of the harm of male-on-female rape in patriarchal societies and, on the basis of this account, to generate suggestions that could be of use in the recovery process for survivors of this type of rape. In order to reach these aims my thesis is divided into three parts. In the first part, I propose a phenomenologically based account of women’s situation as a group under patriarchy, according to which women as a group are subjugated to the hegemonic rule of patriarchal ideology. I argue, further, that the meaning, place and pervasiveness of sexual objectification in the lives of women under patriarchy typically results in women’s alienation from their bodies and creates an atmosphere of threat under which women qua women are especially vulnerable to rape. In the second part, I explore the lived experience of the harm of rape; focusing, first, on the reflexive process whereby a survivor attempts to understand how she has been harmed and, second, on providing explanations based on shared features in the lives of women for two phenomena reported to be experienced by rape victims in the aftermath of the trauma, which I call ‘shattering’ and ‘fragmentation'. My discussion of the lived experience of the harm of rape is meant to supplement existing accounts in the contemporary literature that, I argue, are limited to a thirdperson, objective point of view and so fail to provide a link between the harms they describe and the victim’s actual experience of these harms. Finally, I defend two suggestions for the building up of the survivor’s agency and personhood in the aftermath of rape—the deliberate therapeutic use of feminist consciousness-raising and the use of narrative understanding. , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
- Authors: Kelland, Lindsay-Ann
- Date: 2013-04-19
- Subjects: Rape -- Social aspects--Research -- South Africa Rape -- Psychological aspects -- Research -- South Africa Rape trauma syndrome -- Research -- South Africa Rape victims -- South Africa Patriarchy -- South Africa Sexual dominance and submission -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2700 , http://hdl.handle.net/10962/d1001582
- Description: The aims of this thesis are twofold: to provide an account of the lived experience of the harm of male-on-female rape in patriarchal societies and, on the basis of this account, to generate suggestions that could be of use in the recovery process for survivors of this type of rape. In order to reach these aims my thesis is divided into three parts. In the first part, I propose a phenomenologically based account of women’s situation as a group under patriarchy, according to which women as a group are subjugated to the hegemonic rule of patriarchal ideology. I argue, further, that the meaning, place and pervasiveness of sexual objectification in the lives of women under patriarchy typically results in women’s alienation from their bodies and creates an atmosphere of threat under which women qua women are especially vulnerable to rape. In the second part, I explore the lived experience of the harm of rape; focusing, first, on the reflexive process whereby a survivor attempts to understand how she has been harmed and, second, on providing explanations based on shared features in the lives of women for two phenomena reported to be experienced by rape victims in the aftermath of the trauma, which I call ‘shattering’ and ‘fragmentation'. My discussion of the lived experience of the harm of rape is meant to supplement existing accounts in the contemporary literature that, I argue, are limited to a thirdperson, objective point of view and so fail to provide a link between the harms they describe and the victim’s actual experience of these harms. Finally, I defend two suggestions for the building up of the survivor’s agency and personhood in the aftermath of rape—the deliberate therapeutic use of feminist consciousness-raising and the use of narrative understanding. , Adobe Acrobat 9.53 Paper Capture Plug-in
- Full Text:
An investigation into the factors that influence the success of small business in Port Elizabeth
- Authors: Wilmot, Chloé Margot
- Date: 2013
- Subjects: Small business -- South Africa -- Port Elizabeth Job creation -- South Africa Entrepreneurship -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1162 , http://hdl.handle.net/10962/d1001629
- Description: South Africa has one of the highest unemployment rates in the world, currently 23.90%. One way for the government and policy-makers of South Africa to address this dire statistic is through the fostering and promotion of entrepreneurship and small business creation. The benefits of entrepreneurship are numerous and can include: increasing a country’s productivity, enhancing the welfare and well-being of its citizens, reducing emigration rates, improving economic development and perhaps, most importantly, increasing employment rates. Worldwide, small businesses within the private sector have become indispensable to sustainable job creation and therefore it is of the utmost importance that small businesses in any economy develop, grow and succeed. Despite the fact that research pertaining to small businesses has increased over the years, little empirical evidence has been established. In particular, research into what makes small businesses successful has been limited. Entrepreneurial activity in South Africa remains less than ideal and therefore it is appropriate that research into the success factors of small businesses in South Africa be investigated. Furthermore, the survival of South African small businesses beyond four to five years of being in operation is estimated at only 20.00%. It is evident that a lack of knowledge exists and with respect to this research the factors found to be the most common determinants of success for small businesses in Port Elizabeth were determined and investigated. Convenience- and snowball sampling techniques were used to identify potential participants. In total 43 usable questionnaires were returned. Methodological triangulation was used to analyse the data, according to descriptive- and inferential statistics, as well as content analysis. This being so, the research was conducted within two paradigms, primarily, the positivist research paradigm and also the phenomenological research paradigm. The key findings of this study indicate personal factors to be the most important success factor group, while the environmental success factor group is considered the least important. The most important factors attributable to the success of participants’ small businesses include: maintaining good customer services skills and relationships; having a strong commitment to product/service quality; and having honest employees with sound professional ii knowledge and a positive morale. The least important success factors include: trade exhibitions and business fairs; small business legislation; and industry structure and competition. Finally, the hypothesis tests indicate that significant differences only exist between: the relationship statuses and business factors and the business sectors and environmental factors. The results of this research have significant practical implications for the various stakeholders of entrepreneurship. It is hoped that the results will add to the existing body of knowledge and in turn aid South Africa in becoming aware of the factors essential for small business success. In doing so, South Africa at large will be able to take full advantage of entrepreneurship and small business creation, which continue to remain well within its reach
- Full Text:
- Date Issued: 2013
- Authors: Wilmot, Chloé Margot
- Date: 2013
- Subjects: Small business -- South Africa -- Port Elizabeth Job creation -- South Africa Entrepreneurship -- South Africa Success in business -- South Africa
- Language: English
- Type: Thesis , Masters , MCom
- Identifier: vital:1162 , http://hdl.handle.net/10962/d1001629
- Description: South Africa has one of the highest unemployment rates in the world, currently 23.90%. One way for the government and policy-makers of South Africa to address this dire statistic is through the fostering and promotion of entrepreneurship and small business creation. The benefits of entrepreneurship are numerous and can include: increasing a country’s productivity, enhancing the welfare and well-being of its citizens, reducing emigration rates, improving economic development and perhaps, most importantly, increasing employment rates. Worldwide, small businesses within the private sector have become indispensable to sustainable job creation and therefore it is of the utmost importance that small businesses in any economy develop, grow and succeed. Despite the fact that research pertaining to small businesses has increased over the years, little empirical evidence has been established. In particular, research into what makes small businesses successful has been limited. Entrepreneurial activity in South Africa remains less than ideal and therefore it is appropriate that research into the success factors of small businesses in South Africa be investigated. Furthermore, the survival of South African small businesses beyond four to five years of being in operation is estimated at only 20.00%. It is evident that a lack of knowledge exists and with respect to this research the factors found to be the most common determinants of success for small businesses in Port Elizabeth were determined and investigated. Convenience- and snowball sampling techniques were used to identify potential participants. In total 43 usable questionnaires were returned. Methodological triangulation was used to analyse the data, according to descriptive- and inferential statistics, as well as content analysis. This being so, the research was conducted within two paradigms, primarily, the positivist research paradigm and also the phenomenological research paradigm. The key findings of this study indicate personal factors to be the most important success factor group, while the environmental success factor group is considered the least important. The most important factors attributable to the success of participants’ small businesses include: maintaining good customer services skills and relationships; having a strong commitment to product/service quality; and having honest employees with sound professional ii knowledge and a positive morale. The least important success factors include: trade exhibitions and business fairs; small business legislation; and industry structure and competition. Finally, the hypothesis tests indicate that significant differences only exist between: the relationship statuses and business factors and the business sectors and environmental factors. The results of this research have significant practical implications for the various stakeholders of entrepreneurship. It is hoped that the results will add to the existing body of knowledge and in turn aid South Africa in becoming aware of the factors essential for small business success. In doing so, South Africa at large will be able to take full advantage of entrepreneurship and small business creation, which continue to remain well within its reach
- Full Text:
- Date Issued: 2013
Regulating cartel activity in South Africa
- Authors: Mushi, Walter
- Date: 2012
- Subjects: South Africa. -- Competition Act, 1998 , Antitrust law -- South Africa , Competition
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10286 , http://hdl.handle.net/10948/d1018685
- Description: Competition among firms is a central feature in all free market economies such as South Africa. One of the biggest threats to competition is the presence of cartels in markets. Cartels are firms which collude and compete unfairly in order to obtain monopoly-like profits. For more than fifty years South Africa’s economic landscape has been dominated by a vast network of cartels invital industries, such as bread, cement and fertiliser. South Africa promulgated the Competition Act 89 of 1998 to eradicate cartels and promote and maintain competition within the South African economy. The Competition Act 89 of 1998 prohibits cartel activity and provides for a fine of 10% of turn over for firms found to have engaged in cartel activity. For a variety of reasons, these administrative fines have failed to deter firms from commencing and/or continuing to engage in cartel activity. This is evidenced by the increasing number of firms engaged in large -scale cartels in essential industries, such as construction and food. Public outcry and global trends have persuaded legislators to enactment more stringent penalties in the Competition Amendment Act 1 of 2009. Section 12 of the Competition Amendment Act , which inserts section 73A, creates a cartel of fence in terms of which a director who causes his firm to engage in cartel activity faces ten year imprisonment or a fine of R500, 000. This research shall critically analyse the Competition Amendment Acts effect on deterring cartel activity in South Africa. Despite the legislators’ aim to provide a bigger deterrent for engaging in cartel activity, section 73A of the Competition Amendment Act arouses scrutiny. Firstly, the promulgation of the new cartel offence is contrary to the decimalisation trend in South African company law which recognises the difficulty in enforcing complex regulatory offences with criminal provisions. Secondly, Section 73(5)A appears to infringe an accused director's right to be presumed innocent. Lastly there are co-ordination issues between the National Prosecuting Authority and the Corporate Leniency Policy relating to the granting of prose cutorial immunity for firms which cooperate with the Competition Commission. There search will out line these problems in full. With regards to the problems caused by section 73A, the research will use a comparative analysis with the positionin the United States. Of all the jurisdictions which criminalise cartel activity, the United States was one of the earliest and the most prolific insecuring convictions for directors who cause their firms to engage in cartel activity. The United States has taken innovative steps to supplement their public cartel enforcement drive such as the prosecution of international cartels and the use of private actions. In this regard, the research will extrapolate favourable cartel enforcement measures from the United States for recommendation in order to assist with South Africa’s cartel enforcement and alleviate the problems caused by section 73A, outlined above.
- Full Text:
- Date Issued: 2012
- Authors: Mushi, Walter
- Date: 2012
- Subjects: South Africa. -- Competition Act, 1998 , Antitrust law -- South Africa , Competition
- Language: English
- Type: Thesis , Masters , LLM
- Identifier: vital:10286 , http://hdl.handle.net/10948/d1018685
- Description: Competition among firms is a central feature in all free market economies such as South Africa. One of the biggest threats to competition is the presence of cartels in markets. Cartels are firms which collude and compete unfairly in order to obtain monopoly-like profits. For more than fifty years South Africa’s economic landscape has been dominated by a vast network of cartels invital industries, such as bread, cement and fertiliser. South Africa promulgated the Competition Act 89 of 1998 to eradicate cartels and promote and maintain competition within the South African economy. The Competition Act 89 of 1998 prohibits cartel activity and provides for a fine of 10% of turn over for firms found to have engaged in cartel activity. For a variety of reasons, these administrative fines have failed to deter firms from commencing and/or continuing to engage in cartel activity. This is evidenced by the increasing number of firms engaged in large -scale cartels in essential industries, such as construction and food. Public outcry and global trends have persuaded legislators to enactment more stringent penalties in the Competition Amendment Act 1 of 2009. Section 12 of the Competition Amendment Act , which inserts section 73A, creates a cartel of fence in terms of which a director who causes his firm to engage in cartel activity faces ten year imprisonment or a fine of R500, 000. This research shall critically analyse the Competition Amendment Acts effect on deterring cartel activity in South Africa. Despite the legislators’ aim to provide a bigger deterrent for engaging in cartel activity, section 73A of the Competition Amendment Act arouses scrutiny. Firstly, the promulgation of the new cartel offence is contrary to the decimalisation trend in South African company law which recognises the difficulty in enforcing complex regulatory offences with criminal provisions. Secondly, Section 73(5)A appears to infringe an accused director's right to be presumed innocent. Lastly there are co-ordination issues between the National Prosecuting Authority and the Corporate Leniency Policy relating to the granting of prose cutorial immunity for firms which cooperate with the Competition Commission. There search will out line these problems in full. With regards to the problems caused by section 73A, the research will use a comparative analysis with the positionin the United States. Of all the jurisdictions which criminalise cartel activity, the United States was one of the earliest and the most prolific insecuring convictions for directors who cause their firms to engage in cartel activity. The United States has taken innovative steps to supplement their public cartel enforcement drive such as the prosecution of international cartels and the use of private actions. In this regard, the research will extrapolate favourable cartel enforcement measures from the United States for recommendation in order to assist with South Africa’s cartel enforcement and alleviate the problems caused by section 73A, outlined above.
- Full Text:
- Date Issued: 2012
Spermiogenesis, sperm ultrastructure and reproductive tract morphology in cicadas implications for systematic relationships
- Chawanji, Abraham Simbarashe
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
- Full Text:
- Date Issued: 2007
- Authors: Chawanji, Abraham Simbarashe
- Date: 2007
- Subjects: Cicadas Cicadas -- Reproduction Spermiogenesis in animals
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5770 , http://hdl.handle.net/10962/d1005458
- Description: Sperm structure in five species of cicadine cicadas (Albanycada albigera, Azanicada zuluensis, Platypleura capensis, P. hirtipennis and Pycna semiclara) and five species of cicadettine cicadas (Melampsalta leucoptera, Quintilia walkeri, Stagira simplex, Xosopsaltria thunbergi and Monomatapa matoposa) was investigated by light and electron microscopy. In addition, spermiogenesis in cicadas was described; the information was derived from two cicadettines (Diceroprocta biconica and M. matoposa) and three cicadines (Kongota punctigera, P. capensis and P. semiclara). Mature spermatozoa of all species investigated are elongate and filiform, consisting of three distinct regions: the head (acrosome and nucleus), mid-piece and tail. All species produce more than one discrete length of nucleated, motile sperm, a form of sperm polymorphism termed polymegaly. Polymegaly is expressed in three ways; sperm have uni-, bi- or trimodal nucleus and tail lengths. Besides the differences in length, there are also notable differences in the size of nuclei. The anterior parts of sperm heads are embedded in an elongate homogenous matrix forming spermatodesmata. The conical acrosome is deeply invaginated posteriorly, and sits on top of the nucleus. The acrosomal contents are differentiated internally with a tubular substructure and a subacrosomal space. The anterior of the nucleus intrudes into the posterior section of the subacrosomal space. Anteriorly the acrosome is laterally flattened; posteriorly it extends as two tubular processes on either side of the nucleus that gradually decrease in diameter. The homogenously electron-dense nucleus is pointed anteriorly and is generally cylindrical, although posteriorly there is a lateral invagination that extends part-way along the nucleus. This invagination houses fine granular material of the putative centriolar adjunct which does not form in close proximity to the centriole and hence may not be a true centriolar adjunct. The lamellate disposition of the centriolar adjunct material within the sperm-midpiece of cicadettine cicadas is distinct, and separates these cicadas from their cicadine counterparts in which the centriolar adjunct material is non-lamellate. Vesicle-like elements that are associated with both the posterior nucleus and the centriolar adjunct are also found within the invagination. Immediately posterior of and adjoining the centriolar adjunct is a pair of mitochondrial derivatives that are elongated and extend for almost the entire length of the tail. Except for size the architecture of short and long spermatozoa is generally similar in all species. The absence of accessory bodies in cicada sperm suggests that within the Cicadomorpha, the families Cicadidae and Cercopidae are closely related. Only long nuclei were observed in the fertilized eggs of A. zuluensis indicating that sperm with long nuclei might be favoured for fertilization. Spermiogenesis involves: (a) development of the acrosome from a proacrosomal granule; (b) development of the nucleus, characterized by elongation and streamlining with a simultaneous condensation of chromatin; (c) development of the axoneme from the centriole; (d) amalgamation of individual small mitochondria to form elongated mitochondrial derivatives in which cristae are arranged into regularly spaced lamellae; and (f) elimination of cytoplasm. The presence of a manchette, a transient microtubular organelle, which surrounds the acrosome, nucleus and mitochondrial derivatives, is a characteristic feature of spermiogenesis. The gross morphology of the reproductive tract in both male and female cicadas exhibits an organization similar to that in most oviparous insects. The non-functional spermatheca is the only exceptional feature in the female reproductive tract. Its role has been taken over by the common oviduct which, subsequently, has become modified into a swollen, differentiated structure with a dual role of receiving oocytes from the paired ovaries and storage of spermatozoa. Testis mass varies between cicada species; this variation might be linked to the intensity of sperm competition which has been found to be positively correlated with relative investment in spermatogenesis. Based on the preliminary findings of this study, K. punctigera, with its larger testis relative to body size, would be the ideal candidate to show the greatest levels of sperm competition. Accessory glands in both male and female A. zuluensis, D. biconica, P. hirtipennis and O. quadraticollis are very long; this character might be of phylogenetic significance. Despite being notoriously refractory spermiocladistics is potentially valuable in systematic and phylogenic studies of cicadas, especially at the subfamily level.
- Full Text:
- Date Issued: 2007
African mead biotechnology and indigenous knowledge systems in iQhilika process development
- Authors: Cambray, Garth Anton
- Date: 2005
- Subjects: Biotechnology Indigenous peoples -- Africa Ethnoscience -- Africa Mead -- Africa Brewing -- Microbiology Honeybee Honey
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3929 , http://hdl.handle.net/10962/d1003988
- Description: While the production of mead, a fermented honey beverage, has declined in popularity around the world in recent centuries, a substantial mead industry continues to exist in Africa with an estimated annual production of 1 to 1.7 billion litres. This is largely an ‘invisible industry’, and has functioned outside the formal economy due to proscription of indigenous beverages during colonial times. The traditional African mead industry is, however, also now under pressure due to the environmental degradation of scarce natural ingredients, urbanisation and loss of indigenous knowledge systems (IKS) and, with time, the beverage will likely follow the declining trend of mead consumption observed elsewhere. An analysis of early reports of African mead production suggested that the Khoi-San, among the earliest inhabitants of the continent, are the originators of the mead making techniques which use fibrous plant materials derived from specific plant species, to facilitate mead fermentation in some way. The Eastern Cape represents a region with a large body of Khoi-San IKS preserved in their descendants among the Afrikaans and Xhosa populations. A survey to establish a baseline of mead-making technology in the Eastern Cape was undertaken, and involved interviewing traditional mead makers across an area of roughly 100 000 km2, showing that the mead, iQhilika(Xhosa) Kari (Khoi-San/Afrikaans), is produced using a very similar process throughout the region. This involves the roots of a Trichodiadema sp. plant (imoela – Xhosa, karimoer – Afrikaans/Khoi-San), honey, extract of brood and/or pollen and water. Various other fruit sugar sources were also found to be added at times producing seasonal beverages with unique organoleptic properties. A model traditional iQhilika production operation was investigated in order to describe the main features of the process. Biomass immobilised on Trichodiadema root segments was found to be distributed evenly through the profile of the bioreactor resulting in a well mixed fermentation and a productivity of 0.74 g EtOH/l/h. In the initial stages of fermentation, the ethanol yield was highest in the mid-regions of the bioreactor, but with time the regions closer to the surface, which had atmospheric contact had a higher yield. This phenomenon was attributed to aerobic fatty acid synthesis which allowed the yeast close to the surface to function more efficiently despite rising ethanol concentrations. The mead contained 44.25 g/l (7 % volume) ethanol produced in a fermentation time of 43.5 h. Yeast biomass in the traditional process was either immobilised in the form of flocs or attached to the Trichodiadema intonsum support. Electron microscopy revealed that the cells were covered in a layer of extra-cellular polymeric substance apparently assisting the immobilization, and which was populated by a consortium of yeasts and bacteria. Yeasts isolated from iQhilika brewed in two regions separated by 350 km were found to be very closely related Saccharomyces cerevisiae strains as determined by molecular genetic analysis. The traditional beverage was found to contain populations of Lactic acid bacteria (LAB), which are known spoilage organisms in other beverages. Spoilage characteristics of these organisms matched descriptions of spoilage provided by the IKS survey. Other possibly beneficial LAB, which may contribute useful flavour compounds, were also found to be present in the system. The basic functional aspects of the traditional process were used to design a continuous bench-scale tower bioreactor and process development was based on the IKS survey. This consisted of a packed bed bioreactor, consisting of 2 mm3 T. intonsum root segments, immobilising a novel Saccharomyces cerevisiae strain isolated from a traditional batch of iQhilika. The bioreactor performed well with a yield of close to the theoretical maximum and an ethanol productivity of 3.45 g EtOH/l/h. The parameters of the 5.6 l/d bench-scale bioreactor were used to design a full-scale production bioreactor with a planned maximum output of 330 l/d. This bioreactor had a productivity of 0.19 g EtOH/l/h. The organoleptic properties of the product produced were considered by a taste panel to be better than those of the product of the bench-scale tower bioreactor. This research was based on the development of IKS which imposed a number of constraints and obligations on the project to ensure environmental, and social, in addition to financial viability of the scale-up operation. Makana Meadery was established in partnership with Rhodes University as an empowerment company which, in addition to undertaking the commercialisation of the iQhilika process, would also develop methods for the production of scarce ingredients traditionally unsustainably sourced from fragile ecosystems, provide beekeeping training and the manufacture of beehives.
- Full Text:
- Date Issued: 2005
- Authors: Cambray, Garth Anton
- Date: 2005
- Subjects: Biotechnology Indigenous peoples -- Africa Ethnoscience -- Africa Mead -- Africa Brewing -- Microbiology Honeybee Honey
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3929 , http://hdl.handle.net/10962/d1003988
- Description: While the production of mead, a fermented honey beverage, has declined in popularity around the world in recent centuries, a substantial mead industry continues to exist in Africa with an estimated annual production of 1 to 1.7 billion litres. This is largely an ‘invisible industry’, and has functioned outside the formal economy due to proscription of indigenous beverages during colonial times. The traditional African mead industry is, however, also now under pressure due to the environmental degradation of scarce natural ingredients, urbanisation and loss of indigenous knowledge systems (IKS) and, with time, the beverage will likely follow the declining trend of mead consumption observed elsewhere. An analysis of early reports of African mead production suggested that the Khoi-San, among the earliest inhabitants of the continent, are the originators of the mead making techniques which use fibrous plant materials derived from specific plant species, to facilitate mead fermentation in some way. The Eastern Cape represents a region with a large body of Khoi-San IKS preserved in their descendants among the Afrikaans and Xhosa populations. A survey to establish a baseline of mead-making technology in the Eastern Cape was undertaken, and involved interviewing traditional mead makers across an area of roughly 100 000 km2, showing that the mead, iQhilika(Xhosa) Kari (Khoi-San/Afrikaans), is produced using a very similar process throughout the region. This involves the roots of a Trichodiadema sp. plant (imoela – Xhosa, karimoer – Afrikaans/Khoi-San), honey, extract of brood and/or pollen and water. Various other fruit sugar sources were also found to be added at times producing seasonal beverages with unique organoleptic properties. A model traditional iQhilika production operation was investigated in order to describe the main features of the process. Biomass immobilised on Trichodiadema root segments was found to be distributed evenly through the profile of the bioreactor resulting in a well mixed fermentation and a productivity of 0.74 g EtOH/l/h. In the initial stages of fermentation, the ethanol yield was highest in the mid-regions of the bioreactor, but with time the regions closer to the surface, which had atmospheric contact had a higher yield. This phenomenon was attributed to aerobic fatty acid synthesis which allowed the yeast close to the surface to function more efficiently despite rising ethanol concentrations. The mead contained 44.25 g/l (7 % volume) ethanol produced in a fermentation time of 43.5 h. Yeast biomass in the traditional process was either immobilised in the form of flocs or attached to the Trichodiadema intonsum support. Electron microscopy revealed that the cells were covered in a layer of extra-cellular polymeric substance apparently assisting the immobilization, and which was populated by a consortium of yeasts and bacteria. Yeasts isolated from iQhilika brewed in two regions separated by 350 km were found to be very closely related Saccharomyces cerevisiae strains as determined by molecular genetic analysis. The traditional beverage was found to contain populations of Lactic acid bacteria (LAB), which are known spoilage organisms in other beverages. Spoilage characteristics of these organisms matched descriptions of spoilage provided by the IKS survey. Other possibly beneficial LAB, which may contribute useful flavour compounds, were also found to be present in the system. The basic functional aspects of the traditional process were used to design a continuous bench-scale tower bioreactor and process development was based on the IKS survey. This consisted of a packed bed bioreactor, consisting of 2 mm3 T. intonsum root segments, immobilising a novel Saccharomyces cerevisiae strain isolated from a traditional batch of iQhilika. The bioreactor performed well with a yield of close to the theoretical maximum and an ethanol productivity of 3.45 g EtOH/l/h. The parameters of the 5.6 l/d bench-scale bioreactor were used to design a full-scale production bioreactor with a planned maximum output of 330 l/d. This bioreactor had a productivity of 0.19 g EtOH/l/h. The organoleptic properties of the product produced were considered by a taste panel to be better than those of the product of the bench-scale tower bioreactor. This research was based on the development of IKS which imposed a number of constraints and obligations on the project to ensure environmental, and social, in addition to financial viability of the scale-up operation. Makana Meadery was established in partnership with Rhodes University as an empowerment company which, in addition to undertaking the commercialisation of the iQhilika process, would also develop methods for the production of scarce ingredients traditionally unsustainably sourced from fragile ecosystems, provide beekeeping training and the manufacture of beehives.
- Full Text:
- Date Issued: 2005
On the mocvd growth of ZnO
- Authors: Pagni, Olivier Demeno
- Date: 2004
- Subjects: Zinc oxide thin films , Metal organic chemical vapor deposition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11075 , http://hdl.handle.net/10948/382 , Zinc oxide thin films , Metal organic chemical vapor deposition
- Description: Zinc oxide (ZnO) is a II-VI semiconductor material that offers tremendous potential as a light emitter in the blue-to-UV range. It has a wurtzite structure, and a direct band gap that can be tuned from 3.0 to 4.0 eV by alloying with Cd or Mg, respectively. In this work, ZnO thin films were grown by metalorganic chemical vapor deposition (MOCVD) on n-Si 2 ° off (100), amorphous glass, n-GaAs (100), and c-plane sapphire substrates. Diethyl zinc (DEZn) and tert-butanol (TBOH) were chosen as precursors. For the first time, Second Harmonic Generation Imaging was applied to the mapping of ZnO epilayers. The images obtained highlighted the polycrystalline character of the thin films, and provided insight as to the growth mode of ZnO on Si. The influence of substrate temperature on the structural properties of the epilayers was investigated by X-ray diffraction and optical microscopy. Grain sizes as high as 54 nm were measured. The optimum temperature range for this system proved to be 450 – 500 °C. The influence of the VI:II ratio during growth on the optical properties of the epilayers was studied by UV-vis-near IR spectroscopy. The lowest Urbach tail E0 parameter was measured for material grown at a VI:II ratio of 18:1. The films’ free electron concentration was shown to decrease by over two orders of magnitude, from 1019 to 1017 cm-3, as the VI:II ratio increased from 10 to 60:1. This decrease in carrier concentration with rising VI:II ratio was paralleled to the surge at 12 K of a photoluminescence (PL) emission band characteristic of p-type ZnO. The band gap energies extracted from room temperature transmission spectra ranged between 3.35 and 3.38 eV, in agreement with the value of 3.35 eV measured by room temperature PL. Moreover, variable temperature PL spectra were recorded between 12 and 298 K on ZnO grown on Si. The 12 K spectrum was dominated by a donor-bound exciton (D°X) at 3.36 eV, while the 298 K scan displayed strong free exciton emission (FX) at 3.29 eV. The width of the D°X band proved to be as narrow as 7 meV. The intensity ratio between the room temperature near-band edge emission and the defect-related green band was as high as 28:1, highlighting the optical quality of the layers deposited in this work. The electrical properties of the thin films were studied by Hall measurements (van der Pauw configuration), and a maximum room temperature mobility of 11 cm2/Vs was recorded. Furthermore, a palladium (Pd) Schottky barrier diode on ZnO was fabricated. The barrier height and ideality factor were calculated from current–voltage measurements to be 0.83 eV and 1.6, respectively. The capacitance–voltage curve of the diode yielded a carrier concentration in the depletion region of 8·1017 cm-3. This study has shown that the optical and electrical properties of ZnO depend strongly on the growth conditions employed. A suitable choice of growth parameters can yield high quality ZnO that may be used for various devices. Keywords: Hall, MOCVD, optical spectroscopy, photoluminescence, Schottky barrier diode, SH Imaging, X-ray diffraction, ZnO.
- Full Text:
- Date Issued: 2004
- Authors: Pagni, Olivier Demeno
- Date: 2004
- Subjects: Zinc oxide thin films , Metal organic chemical vapor deposition
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11075 , http://hdl.handle.net/10948/382 , Zinc oxide thin films , Metal organic chemical vapor deposition
- Description: Zinc oxide (ZnO) is a II-VI semiconductor material that offers tremendous potential as a light emitter in the blue-to-UV range. It has a wurtzite structure, and a direct band gap that can be tuned from 3.0 to 4.0 eV by alloying with Cd or Mg, respectively. In this work, ZnO thin films were grown by metalorganic chemical vapor deposition (MOCVD) on n-Si 2 ° off (100), amorphous glass, n-GaAs (100), and c-plane sapphire substrates. Diethyl zinc (DEZn) and tert-butanol (TBOH) were chosen as precursors. For the first time, Second Harmonic Generation Imaging was applied to the mapping of ZnO epilayers. The images obtained highlighted the polycrystalline character of the thin films, and provided insight as to the growth mode of ZnO on Si. The influence of substrate temperature on the structural properties of the epilayers was investigated by X-ray diffraction and optical microscopy. Grain sizes as high as 54 nm were measured. The optimum temperature range for this system proved to be 450 – 500 °C. The influence of the VI:II ratio during growth on the optical properties of the epilayers was studied by UV-vis-near IR spectroscopy. The lowest Urbach tail E0 parameter was measured for material grown at a VI:II ratio of 18:1. The films’ free electron concentration was shown to decrease by over two orders of magnitude, from 1019 to 1017 cm-3, as the VI:II ratio increased from 10 to 60:1. This decrease in carrier concentration with rising VI:II ratio was paralleled to the surge at 12 K of a photoluminescence (PL) emission band characteristic of p-type ZnO. The band gap energies extracted from room temperature transmission spectra ranged between 3.35 and 3.38 eV, in agreement with the value of 3.35 eV measured by room temperature PL. Moreover, variable temperature PL spectra were recorded between 12 and 298 K on ZnO grown on Si. The 12 K spectrum was dominated by a donor-bound exciton (D°X) at 3.36 eV, while the 298 K scan displayed strong free exciton emission (FX) at 3.29 eV. The width of the D°X band proved to be as narrow as 7 meV. The intensity ratio between the room temperature near-band edge emission and the defect-related green band was as high as 28:1, highlighting the optical quality of the layers deposited in this work. The electrical properties of the thin films were studied by Hall measurements (van der Pauw configuration), and a maximum room temperature mobility of 11 cm2/Vs was recorded. Furthermore, a palladium (Pd) Schottky barrier diode on ZnO was fabricated. The barrier height and ideality factor were calculated from current–voltage measurements to be 0.83 eV and 1.6, respectively. The capacitance–voltage curve of the diode yielded a carrier concentration in the depletion region of 8·1017 cm-3. This study has shown that the optical and electrical properties of ZnO depend strongly on the growth conditions employed. A suitable choice of growth parameters can yield high quality ZnO that may be used for various devices. Keywords: Hall, MOCVD, optical spectroscopy, photoluminescence, Schottky barrier diode, SH Imaging, X-ray diffraction, ZnO.
- Full Text:
- Date Issued: 2004
Action research case studies of participatory materials development in two community contexts in Zambia
- Authors: Lupele, Justin Kalaba
- Date: 2003
- Subjects: Community development -- Zambia -- Case studies Environmental education -- Zambia -- Case studies Sustainable development -- Zambia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1417 , http://hdl.handle.net/10962/d1003298
- Description: This research reports on two action research case studies of participatory materials development in two rural community contexts in Zambia, namely Chiawa and Nalusanga. It aims to explore and articulate the relationships between community-based environmental education and participatory materials development in the WWF Zambia Education Project context; clarify participatory materials development processes by identifying the roles of different ‘actors’ in these processes and identify and analyse the contextual and other factors that may influence development and use of environmental education materials in rural communities. These aims were explored by means of a number of action research cycles of inquiry in the two communities. The study also articulates the significance of considering ambivalent globalising influences such as international conferences, debates, overseas development aid, national policies and how these shape and influence materials development work in a local context. In order to gain more insight into the local contexts, I developed contextual profiles on the two communities. These capture the contextual factors that influenced the participatory materials development processes. They include issues such as language, ethnicity, literacy, power relations and the local social economy, amongst others. Although this study has been predominately guided by the socially critical orientation to research and education, I have drawn on aspects of other research orientations. I have also explored some of the emerging critiques of the socially critical orientation. The findings of this study reveal the different roles participants can play in participatory materials development; participatory materials development processes as a learning process; the dynamics of participation in an African context; the role of language and literacy in materials development; the need for open-ended process models of learning amongst adult learners and the importance of merging expert and local knowledge in participatory materials development. This study opens up possibilities for further exploration of participatory materials development processes within the WWF ZEP context and beyond.
- Full Text:
- Date Issued: 2003
- Authors: Lupele, Justin Kalaba
- Date: 2003
- Subjects: Community development -- Zambia -- Case studies Environmental education -- Zambia -- Case studies Sustainable development -- Zambia -- Case studies
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1417 , http://hdl.handle.net/10962/d1003298
- Description: This research reports on two action research case studies of participatory materials development in two rural community contexts in Zambia, namely Chiawa and Nalusanga. It aims to explore and articulate the relationships between community-based environmental education and participatory materials development in the WWF Zambia Education Project context; clarify participatory materials development processes by identifying the roles of different ‘actors’ in these processes and identify and analyse the contextual and other factors that may influence development and use of environmental education materials in rural communities. These aims were explored by means of a number of action research cycles of inquiry in the two communities. The study also articulates the significance of considering ambivalent globalising influences such as international conferences, debates, overseas development aid, national policies and how these shape and influence materials development work in a local context. In order to gain more insight into the local contexts, I developed contextual profiles on the two communities. These capture the contextual factors that influenced the participatory materials development processes. They include issues such as language, ethnicity, literacy, power relations and the local social economy, amongst others. Although this study has been predominately guided by the socially critical orientation to research and education, I have drawn on aspects of other research orientations. I have also explored some of the emerging critiques of the socially critical orientation. The findings of this study reveal the different roles participants can play in participatory materials development; participatory materials development processes as a learning process; the dynamics of participation in an African context; the role of language and literacy in materials development; the need for open-ended process models of learning amongst adult learners and the importance of merging expert and local knowledge in participatory materials development. This study opens up possibilities for further exploration of participatory materials development processes within the WWF ZEP context and beyond.
- Full Text:
- Date Issued: 2003
Parasitism and invasive species : an ecological study of mussel populations
- Calvo Ugarteburu, Miren Gurutze
- Authors: Calvo Ugarteburu, Miren Gurutze
- Date: 1997
- Subjects: Perna -- Parasites Mytilidae -- Parasites Perna -- Ecology Mytilidae -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5736 , http://hdl.handle.net/10962/d1005422
- Description: The Mediterranean mussel Mytilus galloprovincialis, was introduced accidentally to South Africa and has since become invasive. One possible explanation for the success of this species is that it has been released from the effects of parasites which affect the indigenous species of mussels. The aim of this work was to examine the parasitic load of different mussel populations along the southern African coast and to assess the effects of parasites on their hosts. A survey was done to quantify the levels of parasitism in indigenous populations of Perna perna from Southern Africa and of Mytilus galloprovincialis from South Africa (where it is exotic) and Spain (where it is indigenous). This survey was carried out at three different geographic scales: small scale (metres), studying the incidence of parasites within a mussel bed; medium scale (kilometres to tens of kilometres), comparing prevalences of infection among different localities; and large scale (hundreds to thousands of kilometres), examining infection rates along the Southern African coast, as well as the coast of the Basque Country (North Spain). During this survey metazoan parasites other than trematodes were rare. Four species of trematodes were commonly found infecting the indigenous mussel Perna perna. These were metacercariae of the genus Proctoeces, bucephalid sporocysts, encysted metacercariae on the labial palps and gelatinous cysts with metacercariae inside. A detailed description of Proctoeces is given; the other parasites are described elsewhere. No parasites were found in M. galloprovincialis either in South Africa or in Spain. This thesis concentrates on the study of prevalences of Proctoeces and bucephalid sporocysts and their effects on Perna perna. Infection rates with Proctoeces are highly dependent on the sex of the host, with more females than males being infected, and are also size dependent, though only for females. Identification of the sex of mussels infected with bucephalid sporocysts is often not possible since the sporocysts spread over the gonad and replace it. Prevalence of infection with this parasite also increases with the size of the host. To study the influence of Proctoeces and bucephalid sporocysts on the ecological fitness of Perna perna, their effects on survival and competitive ability were tested. The results showed significant negative effects. Both parasites significantly depressed condition but only after spawning, when the mussels were already stressed. In order to check for effects on host survival, the effects of both parasites on mortality rates, gaping behaviour and water loss of mussels exposed to air were also examined. Neither parasite affected mortality rate or gaping behaviour of Perna perna. Proctoeces did not affect the amount of water lost by mussels, but the bucephalid sporocysts did. Mussels infected with sporocysts lost significantly more water than non-infected individuals. This increase in water loss was not related to the gaping behaviour, but a test of the strength of the adductor muscles showed that less force was needed to open mussels with bucephalid sporocysts than non-infected mussels. This was not the case for mussels infected by Proctoeces. Weaker mussels will fail to seal the valves properly, resulting in an increase of water loss on exposure to air by evaporation. Another factor that will have an obvious effect on a population is the reproductive output of the animals. Histological sections of the gonad of infected and non-infected females were cut to study the effects of both parasites on reproduction. Statistical tests comparing the numbers and sizes of oocytes in females infected with Proctoeces and non-infected females showed no significant differences. However, bucephalid sporocysts have a dramatic effect on reproduction by castrating the host, leaving no trace of sex products. One of the major factors shaping the composition of a mussel bed is competition for space and food, with smaller mussels being at a competitive disadvantage. Thus, in order to examine effects of both parasites on the competitive ability of Perna perna, summer and winter growth rates were compared for infected and non-infected mussels. Proctoeces reduced growth both in summer and in winter whilst bucephalid sporocysts had no significant effect. Both growth and reproduction are important components of the energy budget of an animal, and each is affected by either Proctoeces or the bucephalid sporocysts. In an attempt to test if Perna perna compensates energetically for these negative effects, filtration rates and oxygen consumption of mussels with and without parasites were measured. Neither parasite had a significant effect on filtration rates or oxygen consumption of the host. All these results indicate that both Proctoeces and the bucephalid sporocysts have a detrimental effect on their host, and that the mussels do not compensate for these negative effects. There is neither an increase in filtration, nor a decrease in respiration to balance the energy lost to the parasite. The two parasites studied affect the host in different but complementary ways. The effects of both parasites are concentrated on those size classes of mussel which channel most energy into the portion of the energy budget affected by the parasite. Proctoeces affects growth only in the smaller individuals, which under normal conditions would put most energy into growth; and the bucephalid sporocysts castrate the bigger mussels, which would expend most energy on reproduction. By reducing growth rates of small mussels or castrating large mussels, these parasites effectively remove them from the breeding population and reduce their competitive abilities. These negative effects, together with the high prevalence of both parasites in Perna perna along the South African coast and their absence in Mytilus galloprovincialis, suggest that parasites may be an important reason for the success of Mytilus.
- Full Text:
- Date Issued: 1997
- Authors: Calvo Ugarteburu, Miren Gurutze
- Date: 1997
- Subjects: Perna -- Parasites Mytilidae -- Parasites Perna -- Ecology Mytilidae -- Ecology
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5736 , http://hdl.handle.net/10962/d1005422
- Description: The Mediterranean mussel Mytilus galloprovincialis, was introduced accidentally to South Africa and has since become invasive. One possible explanation for the success of this species is that it has been released from the effects of parasites which affect the indigenous species of mussels. The aim of this work was to examine the parasitic load of different mussel populations along the southern African coast and to assess the effects of parasites on their hosts. A survey was done to quantify the levels of parasitism in indigenous populations of Perna perna from Southern Africa and of Mytilus galloprovincialis from South Africa (where it is exotic) and Spain (where it is indigenous). This survey was carried out at three different geographic scales: small scale (metres), studying the incidence of parasites within a mussel bed; medium scale (kilometres to tens of kilometres), comparing prevalences of infection among different localities; and large scale (hundreds to thousands of kilometres), examining infection rates along the Southern African coast, as well as the coast of the Basque Country (North Spain). During this survey metazoan parasites other than trematodes were rare. Four species of trematodes were commonly found infecting the indigenous mussel Perna perna. These were metacercariae of the genus Proctoeces, bucephalid sporocysts, encysted metacercariae on the labial palps and gelatinous cysts with metacercariae inside. A detailed description of Proctoeces is given; the other parasites are described elsewhere. No parasites were found in M. galloprovincialis either in South Africa or in Spain. This thesis concentrates on the study of prevalences of Proctoeces and bucephalid sporocysts and their effects on Perna perna. Infection rates with Proctoeces are highly dependent on the sex of the host, with more females than males being infected, and are also size dependent, though only for females. Identification of the sex of mussels infected with bucephalid sporocysts is often not possible since the sporocysts spread over the gonad and replace it. Prevalence of infection with this parasite also increases with the size of the host. To study the influence of Proctoeces and bucephalid sporocysts on the ecological fitness of Perna perna, their effects on survival and competitive ability were tested. The results showed significant negative effects. Both parasites significantly depressed condition but only after spawning, when the mussels were already stressed. In order to check for effects on host survival, the effects of both parasites on mortality rates, gaping behaviour and water loss of mussels exposed to air were also examined. Neither parasite affected mortality rate or gaping behaviour of Perna perna. Proctoeces did not affect the amount of water lost by mussels, but the bucephalid sporocysts did. Mussels infected with sporocysts lost significantly more water than non-infected individuals. This increase in water loss was not related to the gaping behaviour, but a test of the strength of the adductor muscles showed that less force was needed to open mussels with bucephalid sporocysts than non-infected mussels. This was not the case for mussels infected by Proctoeces. Weaker mussels will fail to seal the valves properly, resulting in an increase of water loss on exposure to air by evaporation. Another factor that will have an obvious effect on a population is the reproductive output of the animals. Histological sections of the gonad of infected and non-infected females were cut to study the effects of both parasites on reproduction. Statistical tests comparing the numbers and sizes of oocytes in females infected with Proctoeces and non-infected females showed no significant differences. However, bucephalid sporocysts have a dramatic effect on reproduction by castrating the host, leaving no trace of sex products. One of the major factors shaping the composition of a mussel bed is competition for space and food, with smaller mussels being at a competitive disadvantage. Thus, in order to examine effects of both parasites on the competitive ability of Perna perna, summer and winter growth rates were compared for infected and non-infected mussels. Proctoeces reduced growth both in summer and in winter whilst bucephalid sporocysts had no significant effect. Both growth and reproduction are important components of the energy budget of an animal, and each is affected by either Proctoeces or the bucephalid sporocysts. In an attempt to test if Perna perna compensates energetically for these negative effects, filtration rates and oxygen consumption of mussels with and without parasites were measured. Neither parasite had a significant effect on filtration rates or oxygen consumption of the host. All these results indicate that both Proctoeces and the bucephalid sporocysts have a detrimental effect on their host, and that the mussels do not compensate for these negative effects. There is neither an increase in filtration, nor a decrease in respiration to balance the energy lost to the parasite. The two parasites studied affect the host in different but complementary ways. The effects of both parasites are concentrated on those size classes of mussel which channel most energy into the portion of the energy budget affected by the parasite. Proctoeces affects growth only in the smaller individuals, which under normal conditions would put most energy into growth; and the bucephalid sporocysts castrate the bigger mussels, which would expend most energy on reproduction. By reducing growth rates of small mussels or castrating large mussels, these parasites effectively remove them from the breeding population and reduce their competitive abilities. These negative effects, together with the high prevalence of both parasites in Perna perna along the South African coast and their absence in Mytilus galloprovincialis, suggest that parasites may be an important reason for the success of Mytilus.
- Full Text:
- Date Issued: 1997
Entrants to training college : an investigation into the ability in, aptitude for and attitude towards arithmetic and mathematics, displayed by entrants to training colleges for White persons in the Cape Province
- Authors: Venter, Ian Andri
- Date: 1973
- Subjects: Arithmetic -- Study and teaching (Elementary) -- South Africa Mathematics -- Study and teaching (Elementary) -- South Africa Mathematics -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1916 , http://hdl.handle.net/10962/d1007283
- Description: In many cases topics for research are presented to a student in capsulated, clearly defined terms, either as the result of his own experience or as a request by some institution. In other cases the topic takes shape but gradually, very often as the result of a student slowly becoming aware of a field of research through repeated observation of related factors. In some cases the aim of research is to determine whether there is a relationship between various factors; or disprove such in others the main aim may be to prove relationship in unequivocal terms. A large body of research is, however, concerned mainly with the statement of a problem or the finding of facts. The work presented in the following pages can be regarded as falling in the last-mentioned category. A vague suspicion was gradually strengthened by observation and experience until it finally crystallised to form the basis of the research. Facts and figures were gathered and analysed and some conclusions drawn, conclusions that gave rise to more questions and problems than fall within the scope of this work. It was, in fact, found that this research raised more questions than were answered by it and served mainly to underline the magnitude of the problem rather than to offer a solution.
- Full Text:
- Date Issued: 1973
- Authors: Venter, Ian Andri
- Date: 1973
- Subjects: Arithmetic -- Study and teaching (Elementary) -- South Africa Mathematics -- Study and teaching (Elementary) -- South Africa Mathematics -- Study and teaching (Secondary) -- South Africa
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1916 , http://hdl.handle.net/10962/d1007283
- Description: In many cases topics for research are presented to a student in capsulated, clearly defined terms, either as the result of his own experience or as a request by some institution. In other cases the topic takes shape but gradually, very often as the result of a student slowly becoming aware of a field of research through repeated observation of related factors. In some cases the aim of research is to determine whether there is a relationship between various factors; or disprove such in others the main aim may be to prove relationship in unequivocal terms. A large body of research is, however, concerned mainly with the statement of a problem or the finding of facts. The work presented in the following pages can be regarded as falling in the last-mentioned category. A vague suspicion was gradually strengthened by observation and experience until it finally crystallised to form the basis of the research. Facts and figures were gathered and analysed and some conclusions drawn, conclusions that gave rise to more questions and problems than fall within the scope of this work. It was, in fact, found that this research raised more questions than were answered by it and served mainly to underline the magnitude of the problem rather than to offer a solution.
- Full Text:
- Date Issued: 1973
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