Evaluating uncertainty in water resources estimation in Southern Africa : a case study of South Africa
- Authors: Sawunyama, Tendai
- Date: 2009
- Subjects: Water supply -- South Africa , Water supply -- Africa, Southern , Hydrology -- South Africa , Hydrology -- Africa, Southern , Hydrologic models , Hydrology research -- South Africa , Hydrology research -- Africa, Southern , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6035 , http://hdl.handle.net/10962/d1006176
- Description: Hydrological models are widely used tools in water resources estimation, but they are simple representations of reality and are frequently based on inadequate input data and uncertainties in parameter values. Data observation networks are expensive to establish and maintain and often beyond the resources of most developing countries. Consequently, measurements are difficult to obtain and observation networks in many countries are shrinking, hence obtaining representative observations in space and time remains a challenge. This study presents some guidelines on the identification, quantification and reduction of sources of uncertainty in water resources estimation in southern Africa, a data scarce region. The analyses are based on example sub-basins drawn from South Africa and the application of the Pitman hydrological model. While it has always been recognised that estimates of water resources availability for the region are subject to possible errors, the quantification of these uncertainties has never been explicitly incorporated into the methods used in the region. The motivation for this study was therefore to contribute to the future development of a revised framework for water resources estimation that does include uncertainty. The focus was on uncertainties associated with climate input data, parameter estimation (and recognizing the uncertainty due model structure deficiencies) methods and water use data. In addition to variance based measures of uncertainty, this study also used a reservoir yield based statistic to evaluate model output uncertainty, which represents an integrated measure of flow regime variations and one that can be more easily understood by water resources managers. Through a sensitivity analysis approach, the results of the individual contribution of each source of uncertainty suggest regional differences and that clear statements about which source of uncertainty is likely to dominate are not generally possible. Parameter sensitivity analysis was used in identifying parameters which are important withinspecific sub-basins and therefore those to focus on in uncertainty analysis. The study used a simple framework for evaluating the combined contribution of uncertainty sources to model outputs that is consistent with the model limitations and data available, and that allows direct quantitative comparison between model outputs obtained by using different sources of information and methods within Spatial and Time Series Information Modelling (SPATSIM) software. The results from combining the sources of uncertainties showed that parameter uncertainty dominates the contribution to model output uncertainty. However, in some parts of the country especially those with complex topography, which tend to experience high rainfall spatial variability, rainfall uncertainty is equally dominant, while the contributions of evaporation and water use data uncertainty are relatively small. While the results of this study are encouraging, the weaknesses of the methods used to quantify uncertainty (especially subjectivity involved in evaluating parameter uncertainty) should not be neglected and require further evaluations. An effort to reduce data and parameter uncertainty shows that this can only be achieved if data access at appropriate scale and quality improves. Perhaps the focus should be on maintaining existing networks and concentrating research efforts on making the most out of the emerging data products derived from remote sensing platforms. While this study presents some initial guidelines for evaluating uncertainty in South Africa, there is need to overcome several constraints which are related to data availability and accuracy, the models used and the capacity or willingness to adopt new methods that incorporate uncertainty. The study has provided a starting point for the development of new approaches to modelling water resources in the region that include uncertain estimates.
- Full Text:
- Date Issued: 2009
- Authors: Sawunyama, Tendai
- Date: 2009
- Subjects: Water supply -- South Africa , Water supply -- Africa, Southern , Hydrology -- South Africa , Hydrology -- Africa, Southern , Hydrologic models , Hydrology research -- South Africa , Hydrology research -- Africa, Southern , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:6035 , http://hdl.handle.net/10962/d1006176
- Description: Hydrological models are widely used tools in water resources estimation, but they are simple representations of reality and are frequently based on inadequate input data and uncertainties in parameter values. Data observation networks are expensive to establish and maintain and often beyond the resources of most developing countries. Consequently, measurements are difficult to obtain and observation networks in many countries are shrinking, hence obtaining representative observations in space and time remains a challenge. This study presents some guidelines on the identification, quantification and reduction of sources of uncertainty in water resources estimation in southern Africa, a data scarce region. The analyses are based on example sub-basins drawn from South Africa and the application of the Pitman hydrological model. While it has always been recognised that estimates of water resources availability for the region are subject to possible errors, the quantification of these uncertainties has never been explicitly incorporated into the methods used in the region. The motivation for this study was therefore to contribute to the future development of a revised framework for water resources estimation that does include uncertainty. The focus was on uncertainties associated with climate input data, parameter estimation (and recognizing the uncertainty due model structure deficiencies) methods and water use data. In addition to variance based measures of uncertainty, this study also used a reservoir yield based statistic to evaluate model output uncertainty, which represents an integrated measure of flow regime variations and one that can be more easily understood by water resources managers. Through a sensitivity analysis approach, the results of the individual contribution of each source of uncertainty suggest regional differences and that clear statements about which source of uncertainty is likely to dominate are not generally possible. Parameter sensitivity analysis was used in identifying parameters which are important withinspecific sub-basins and therefore those to focus on in uncertainty analysis. The study used a simple framework for evaluating the combined contribution of uncertainty sources to model outputs that is consistent with the model limitations and data available, and that allows direct quantitative comparison between model outputs obtained by using different sources of information and methods within Spatial and Time Series Information Modelling (SPATSIM) software. The results from combining the sources of uncertainties showed that parameter uncertainty dominates the contribution to model output uncertainty. However, in some parts of the country especially those with complex topography, which tend to experience high rainfall spatial variability, rainfall uncertainty is equally dominant, while the contributions of evaporation and water use data uncertainty are relatively small. While the results of this study are encouraging, the weaknesses of the methods used to quantify uncertainty (especially subjectivity involved in evaluating parameter uncertainty) should not be neglected and require further evaluations. An effort to reduce data and parameter uncertainty shows that this can only be achieved if data access at appropriate scale and quality improves. Perhaps the focus should be on maintaining existing networks and concentrating research efforts on making the most out of the emerging data products derived from remote sensing platforms. While this study presents some initial guidelines for evaluating uncertainty in South Africa, there is need to overcome several constraints which are related to data availability and accuracy, the models used and the capacity or willingness to adopt new methods that incorporate uncertainty. The study has provided a starting point for the development of new approaches to modelling water resources in the region that include uncertain estimates.
- Full Text:
- Date Issued: 2009
Evaluation of a plant-herbivore system in determining potential efficacy of a candidate biological control agent, cornops aquaticum for water hyacinth, eichhornia crassipes
- Authors: Bownes, Angela
- Date: 2009
- Subjects: Water hyacinth -- Control -- South Africa , Eichhornia crassipedes , Pontederiaceae , Grasshoppers , Biological pest control agents -- South Africa , Weeds -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5687 , http://hdl.handle.net/10962/d1005373
- Description: Water hyacinth, Eichhornia crassipes Mart. Solms-Laubach (Pontederiaceae), a freefloating aquatic macrophyte of Neotropical origin, was introduced into South Africa as an ornamental aquarium plant in the early 1900’s. By the 1970’s it had reached pest proportions in dams and rivers around the country. Due to the sustainability, cost efficiency and low environmental risk associated with biological control, this has been a widely used method in an attempt to reduce infestations to below the threshold where they cause economic and ecological damage. To date, five arthropod and one pathogen biocontrol agents have been introduced for the control of water hyacinth but their impact has been variable. It is believed that their efficacy is hampered by the presence of highly eutrophic systems in South Africa in which plant growth is prolific and the negative effects of herbivory are therefore mitigated. It is for these reasons that new, potentially more damaging biocontrol agents are being considered for release. The water hyacinth grasshopper, Cornops aquaticum Brüner (Orthoptera: Acrididae), which is native to South America and Mexico, was brought into quarantine in Pretoria, South Africa in 1995. Although the grasshopper was identified as one of the most damaging insects associated with water hyacinth in its native range, it has not been considered as a biocontrol agent for water hyacinth anywhere else in the world. After extensive host-range testing which revealed it to be safe for release, a release permit for this candidate agent was issued in 2007. However, host specificity testing is no longer considered to be the only important component of pre-release screening of candidate biocontrol agents. Investigating biological and ecological aspects of the plant-herbivore system that will assist in determination of potential establishment, efficacy and the ability to build up good populations in the recipient environment are some of the important factors. This thesis is a pre-release evaluation of C. aquaticum to determine whether it is sufficiently damaging to water hyacinth to warrant its release. It investigated interactions between the grasshopper and water hyacinth under a range of nutrient conditions found in South African water bodies as well as the impact of the grasshopper on the competitive performance of water hyacinth. Both plant growth rates and the response of water hyacinth to herbivory by the grasshopper were influenced by nutrient availability to the plants. The ability of water hyacinth to compensate for loss of tissue through herbivory was greater under eutrophic nutrient conditions. However, a negative linear relationship was found between grasshopper biomass and water hyacinth performance parameters such as biomass accumulation and leaf production, even under eutrophic conditions. Water hyacinth’s compensatory ability in terms of its potential to mitigate to detrimental effects of insect feeding was dependent on the amount of damage caused by herbivory by the grasshopper. Plant biomass and the competitive ability of water hyacinth in relation to another freefloating aquatic weed species were reduced by C. aquaticum under eutrophic nutrient conditions, in a short space of time. It was also found that grasshopper feeding and characteristics related to their population dynamics such as fecundity and survival were significantly influenced by water nutrient availability and that environmental nutrient availability will influence the control potential of this species should it be released in South Africa. Cornops aquaticum shows promise as a biocontrol agent for water hyacinth but additional factors that were not investigated in this study such as compatibility with the South African climate and the current water hyacinth biocontrol agents need to be combined with these data to make a decision on its release. Possible management options for this species if it is to be introduced into South Africa are discussed.
- Full Text:
- Date Issued: 2009
- Authors: Bownes, Angela
- Date: 2009
- Subjects: Water hyacinth -- Control -- South Africa , Eichhornia crassipedes , Pontederiaceae , Grasshoppers , Biological pest control agents -- South Africa , Weeds -- Biological control -- South Africa , Invasive plants -- Biological control -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5687 , http://hdl.handle.net/10962/d1005373
- Description: Water hyacinth, Eichhornia crassipes Mart. Solms-Laubach (Pontederiaceae), a freefloating aquatic macrophyte of Neotropical origin, was introduced into South Africa as an ornamental aquarium plant in the early 1900’s. By the 1970’s it had reached pest proportions in dams and rivers around the country. Due to the sustainability, cost efficiency and low environmental risk associated with biological control, this has been a widely used method in an attempt to reduce infestations to below the threshold where they cause economic and ecological damage. To date, five arthropod and one pathogen biocontrol agents have been introduced for the control of water hyacinth but their impact has been variable. It is believed that their efficacy is hampered by the presence of highly eutrophic systems in South Africa in which plant growth is prolific and the negative effects of herbivory are therefore mitigated. It is for these reasons that new, potentially more damaging biocontrol agents are being considered for release. The water hyacinth grasshopper, Cornops aquaticum Brüner (Orthoptera: Acrididae), which is native to South America and Mexico, was brought into quarantine in Pretoria, South Africa in 1995. Although the grasshopper was identified as one of the most damaging insects associated with water hyacinth in its native range, it has not been considered as a biocontrol agent for water hyacinth anywhere else in the world. After extensive host-range testing which revealed it to be safe for release, a release permit for this candidate agent was issued in 2007. However, host specificity testing is no longer considered to be the only important component of pre-release screening of candidate biocontrol agents. Investigating biological and ecological aspects of the plant-herbivore system that will assist in determination of potential establishment, efficacy and the ability to build up good populations in the recipient environment are some of the important factors. This thesis is a pre-release evaluation of C. aquaticum to determine whether it is sufficiently damaging to water hyacinth to warrant its release. It investigated interactions between the grasshopper and water hyacinth under a range of nutrient conditions found in South African water bodies as well as the impact of the grasshopper on the competitive performance of water hyacinth. Both plant growth rates and the response of water hyacinth to herbivory by the grasshopper were influenced by nutrient availability to the plants. The ability of water hyacinth to compensate for loss of tissue through herbivory was greater under eutrophic nutrient conditions. However, a negative linear relationship was found between grasshopper biomass and water hyacinth performance parameters such as biomass accumulation and leaf production, even under eutrophic conditions. Water hyacinth’s compensatory ability in terms of its potential to mitigate to detrimental effects of insect feeding was dependent on the amount of damage caused by herbivory by the grasshopper. Plant biomass and the competitive ability of water hyacinth in relation to another freefloating aquatic weed species were reduced by C. aquaticum under eutrophic nutrient conditions, in a short space of time. It was also found that grasshopper feeding and characteristics related to their population dynamics such as fecundity and survival were significantly influenced by water nutrient availability and that environmental nutrient availability will influence the control potential of this species should it be released in South Africa. Cornops aquaticum shows promise as a biocontrol agent for water hyacinth but additional factors that were not investigated in this study such as compatibility with the South African climate and the current water hyacinth biocontrol agents need to be combined with these data to make a decision on its release. Possible management options for this species if it is to be introduced into South Africa are discussed.
- Full Text:
- Date Issued: 2009
Factors influencing survivor qualities after downsizing
- Authors: Chipunza, Crispen
- Date: 2009
- Subjects: Downsizing of organizations -- South Africa , Organizational change -- South Africa , Cost control , Unemployment -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9381 , http://hdl.handle.net/10948/1219 , Downsizing of organizations -- South Africa , Organizational change -- South Africa , Cost control , Unemployment -- Psychological aspects
- Description: Today organisations all over the world have to cope with the ever-increasing rate of local and global change. Those in developing countries have to cope with the inefficiencies engendered by state-led economic, developmental and political strategies, such as new government regulations. These have had an impact on the management of human resources and are exemplified by an increasing adoption of strategies meant to reduce pressure on costs and margins. An increasing popular management response to these challenges has been to engage in some form of organisational restructuring such as downsizing. Often employees who remain (survivors) after downsizing are not given much attention, yet the achievement of new strategic goals depends on the survivors having positive attitudes, relentless commitment and high motivation. Research indicates that employees who are motivated and committed contribute vastly to the financial-bottom-line of the organisation. Therefore, downsizing organisations should continuously search for ways to increase such qualities among their survivors. The objective of this study was to identify the factors that influence the attitudes, commitment and motivation of survivors in a developing economy with a volatile environment. To achieve this objective, a theoretical survivor quality model was presented. In order to present the model, firstly, a literature survey on the importance of survivor quality in terms of attitudes, commitment, and motivation among survivors was conducted. Secondly, literature survey pertaining to the drivers of survivor quality was done, and thirdly, literature dealing with strategies to deal with survivor quality was surveyed. The theoretical survivor quality model was used to compile the research instrument that determined the attitudinal, commitment and motivational levels of survivors, how the three constructs are related after downsizing, as well as the factors influencing the observed levels. The questionnaire was randomly distributed among survivors in the selected manufacturing organisations in Zimbabwe. The empirical results obtained from the study showed that survivors in a developing economy with a volatile environment had moderate levels of attitudes, commitment ad motivation. Two categories of factors were identified as important in influencing these levels. They were downsizing strategy and demographic factors. The downsizing strategy factors were communication and victim support, while education, age, and number of years employed emerged as the demographic factors. The study further highlighted that older survivors with less education contributed more to the moderate levels of attitude, commitment and motivation observed. The study highlights that these variables must be taken into consideration when implementing downsizing in an economically volatile environment in order to manage survivor quality. A further point emanating from the study is that prior to downsizing, organisations should adopt effective communication strategies throughout the process. The key factors identified as influencing survivor quality in this study were integrated into the survivor quality model which can be used by other organisations in a similar context to manage survivor quality in order to increase their efficiency, effectiveness, iv and competitive advantage after downsizing.
- Full Text:
- Date Issued: 2009
- Authors: Chipunza, Crispen
- Date: 2009
- Subjects: Downsizing of organizations -- South Africa , Organizational change -- South Africa , Cost control , Unemployment -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:9381 , http://hdl.handle.net/10948/1219 , Downsizing of organizations -- South Africa , Organizational change -- South Africa , Cost control , Unemployment -- Psychological aspects
- Description: Today organisations all over the world have to cope with the ever-increasing rate of local and global change. Those in developing countries have to cope with the inefficiencies engendered by state-led economic, developmental and political strategies, such as new government regulations. These have had an impact on the management of human resources and are exemplified by an increasing adoption of strategies meant to reduce pressure on costs and margins. An increasing popular management response to these challenges has been to engage in some form of organisational restructuring such as downsizing. Often employees who remain (survivors) after downsizing are not given much attention, yet the achievement of new strategic goals depends on the survivors having positive attitudes, relentless commitment and high motivation. Research indicates that employees who are motivated and committed contribute vastly to the financial-bottom-line of the organisation. Therefore, downsizing organisations should continuously search for ways to increase such qualities among their survivors. The objective of this study was to identify the factors that influence the attitudes, commitment and motivation of survivors in a developing economy with a volatile environment. To achieve this objective, a theoretical survivor quality model was presented. In order to present the model, firstly, a literature survey on the importance of survivor quality in terms of attitudes, commitment, and motivation among survivors was conducted. Secondly, literature survey pertaining to the drivers of survivor quality was done, and thirdly, literature dealing with strategies to deal with survivor quality was surveyed. The theoretical survivor quality model was used to compile the research instrument that determined the attitudinal, commitment and motivational levels of survivors, how the three constructs are related after downsizing, as well as the factors influencing the observed levels. The questionnaire was randomly distributed among survivors in the selected manufacturing organisations in Zimbabwe. The empirical results obtained from the study showed that survivors in a developing economy with a volatile environment had moderate levels of attitudes, commitment ad motivation. Two categories of factors were identified as important in influencing these levels. They were downsizing strategy and demographic factors. The downsizing strategy factors were communication and victim support, while education, age, and number of years employed emerged as the demographic factors. The study further highlighted that older survivors with less education contributed more to the moderate levels of attitude, commitment and motivation observed. The study highlights that these variables must be taken into consideration when implementing downsizing in an economically volatile environment in order to manage survivor quality. A further point emanating from the study is that prior to downsizing, organisations should adopt effective communication strategies throughout the process. The key factors identified as influencing survivor quality in this study were integrated into the survivor quality model which can be used by other organisations in a similar context to manage survivor quality in order to increase their efficiency, effectiveness, iv and competitive advantage after downsizing.
- Full Text:
- Date Issued: 2009
From song to literary texts : a study of the influence of isiXhosa lyrics on selected isiXhosa texts
- Authors: Dlepu, Siziwe Everrette
- Date: 2009
- Subjects: Xhosa (African people) -- Songs and music -- Texts , Folk songs, Xhosa -- South Africa , Xhosa (African people) -- Music , Xhosa -- Music
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8460 , http://hdl.handle.net/10948/943 , Xhosa (African people) -- Songs and music -- Texts , Folk songs, Xhosa -- South Africa , Xhosa (African people) -- Music , Xhosa -- Music
- Description: Songs play a vital role in the everyday life of the AmaXhosa. Each and every occasion or gathering is accompanied by singing. Their anger or pain, sorrow or joy is reflected in their singing. Although these songs are composed for social purposes and entertainment, they are also educational. Songs may be composed and sung to comment on political affairs, complain against the abuse of power by the authorities, declare war, protest, praise a hero, encourage working together and ridicule the foolishness of someone. Vocabulary and diction used in the composition of these songs, relays the message in a clever and witty style. Since the AmaXhosa are intellectuals, irony and satire are used. The satirical or ironical songs hide the meaning and the listener must unravel the real meaning. AmaXhosa singing, chanting and dancing is accompanied by instruments. These instruments add more rhythm to the dance.The AmaXhosa use anything at their disposal when carving their instruments. Their songs may be accompanied by the beating of cow-hide drums, blowing of reed-pipe whistles, animal horns, beating of sticks and hand-clapping. The most important instrument the AmaXhosa use is the human voice. They are experts in humming, gruff singing and whistling. The songs of the AmaXhosa encourage togetherness. When one composes a song, one does not express one’s own feelings, but also the feelings of the community. The AmaXhosa songs are about participation so group singing and dancing is encouraged. Everyone participates either by singing, dancing or clapping. x Respect is the central core of the AmaXhosa songs. That is why the songs are composed according to age groups and sex. Instruments are also used according to ages and sex. Written texts are also a tool to educate the reader. The writers have decided to include songs in their writings to act as a form of entertainment and education. Although some songs lack the hallmarks of a traditional song, they communicate the idea or relay the message the writer wants to convey to the reader. Terms: Mock enconuim, the grotesque and the principle of beautiful deformity, anaphoric construction, diction and connotation, authorial comments, the mask-persona form, usurping of authority and reduction of traditional status.
- Full Text:
- Date Issued: 2009
From song to literary texts : a study of the influence of isiXhosa lyrics on selected isiXhosa texts
- Authors: Dlepu, Siziwe Everrette
- Date: 2009
- Subjects: Xhosa (African people) -- Songs and music -- Texts , Folk songs, Xhosa -- South Africa , Xhosa (African people) -- Music , Xhosa -- Music
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:8460 , http://hdl.handle.net/10948/943 , Xhosa (African people) -- Songs and music -- Texts , Folk songs, Xhosa -- South Africa , Xhosa (African people) -- Music , Xhosa -- Music
- Description: Songs play a vital role in the everyday life of the AmaXhosa. Each and every occasion or gathering is accompanied by singing. Their anger or pain, sorrow or joy is reflected in their singing. Although these songs are composed for social purposes and entertainment, they are also educational. Songs may be composed and sung to comment on political affairs, complain against the abuse of power by the authorities, declare war, protest, praise a hero, encourage working together and ridicule the foolishness of someone. Vocabulary and diction used in the composition of these songs, relays the message in a clever and witty style. Since the AmaXhosa are intellectuals, irony and satire are used. The satirical or ironical songs hide the meaning and the listener must unravel the real meaning. AmaXhosa singing, chanting and dancing is accompanied by instruments. These instruments add more rhythm to the dance.The AmaXhosa use anything at their disposal when carving their instruments. Their songs may be accompanied by the beating of cow-hide drums, blowing of reed-pipe whistles, animal horns, beating of sticks and hand-clapping. The most important instrument the AmaXhosa use is the human voice. They are experts in humming, gruff singing and whistling. The songs of the AmaXhosa encourage togetherness. When one composes a song, one does not express one’s own feelings, but also the feelings of the community. The AmaXhosa songs are about participation so group singing and dancing is encouraged. Everyone participates either by singing, dancing or clapping. x Respect is the central core of the AmaXhosa songs. That is why the songs are composed according to age groups and sex. Instruments are also used according to ages and sex. Written texts are also a tool to educate the reader. The writers have decided to include songs in their writings to act as a form of entertainment and education. Although some songs lack the hallmarks of a traditional song, they communicate the idea or relay the message the writer wants to convey to the reader. Terms: Mock enconuim, the grotesque and the principle of beautiful deformity, anaphoric construction, diction and connotation, authorial comments, the mask-persona form, usurping of authority and reduction of traditional status.
- Full Text:
- Date Issued: 2009
Guidelines for the management of patients with diabetes mellitus at health care clinics in the Cacadu region of the Eastern Cape Province of South Africa
- De Mendonça, Hester Magdalena
- Authors: De Mendonça, Hester Magdalena
- Date: 2009
- Subjects: Diabetics -- Treatment -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DCur
- Identifier: vital:10011 , http://hdl.handle.net/10948/1017 , Diabetics -- Treatment -- South Africa -- Eastern Cape
- Description: Diabetes Mellitus (DM) is the new epidemic in the world with 246 million people suffering from the disease at the moment and a projected increase to 380 million in 2025 (IDF, 2007b:36). The developing countries are the most vulnerable. Statistics state that SA and Egypt have the most diabetics on the continent. Globally, each year 3,8 million deaths are attributable to DM (IDF, 2007a). The Department of Health (DOH) and the Cacadu District Municipality (Eastern Cape) are serving a population of 102 721 in the Kouga and Koukamma areas, which covers an area of 5 992 km², with health care. There are 22 clinics with 28 registered nurses for all the clinics and between 3 and 9 lay health workers (LHWs) per clinic. For the purpose of this research study, the persons suffering from DM (±3550) in this area were taken into consideration (Strydom, 2005). DM is a chronic disorder and therefore patients should be able to manage their disease pattern for the rest of their lives (Healthline, 2008, Mbanya, 2006:12). In order to achieve this, continuous and effective patient education by health care providers are necessary. This disease affects more and more people each passing day, because of the rapid westernisation of the South African population, leading to more people attending clinics in the public health sector (Bonnici, 2002:32). There are specific guidelines laid down by the Department of Health (DOH) pertaining to the control and management of DM. Guidelines include the early diagnosis, treatment and patient education regarding DM (Department of Health, 1997, [revised 2004]). Evidence from previous research studies showed that not all registered nurses are aware of these guidelines and most have not been educated regarding the utilisation of these guidelines (O’Brien, van Rooyen & Carlson, 2006:36-40). In the clinics, the health care givers are confronted with a number of difficulties, such as a lack of funds to enable them to order adequate equipment and medicine. Another problem is the migration of registered nurses out of the country thus; there is also a shortage of staff to operate these clinics (Mkhize, 2004). The organisational structure in the clinics does not function optimally and there is a lack of communication between provincial, district and clinic level. Due to the above-mentioned challenges there is also a lack of efficient auditing systems to ensure quality assurance. Furthermore, a knowledge deficit pertaining to DM and the management thereof in all the groups participating in this study, namely the registered nurses, the lay health workers (LHWs) and the diabetic patients was found. The empowerment process of the LHW is not explored fully and therefore not executed to its full potential. To be able to improve the management of DM in this region, it is important to know what the difficulties are that the health care givers as well as the patients experience in relation to this issue. This study therefore explored and described these difficulties. The research was based on a qualitative, quantitative, explorative, descriptive and contextual research design. Health care givers as well as diabetic patients attending clinics in the Cacadu region of the Eastern Cape have been requested to complete questionnaires pertaining to their knowledge of Diabetes Mellitus. The current organisational structure of the provincial department of health was explored and findings analysed using the activities of the management process (Muller, 2006:106). The SA Government is committed to combining the national human resource development strategy with the rapid upgrading of service delivery to all of the nation’s communities. Stemming from this undertaking, suitable members of the community are to be trained as LHWs. LHWs are to play an integral role in strengthening the abilities of the community to empower themselves to participate and take responsibility for their own health and wellness (Department of Health, 2001a:4). From the research, it was found that the above-mentioned national plan had been implemented, but is not functioning at optimum level due to several shortcomings/deficits. Proposed guidelines were therefore designed to address the shortcomings and fragmentation of the plan. As specific knowledge deficits in DM were identified during this research study, general educational guidelines were included for the registered nurses and the diabetic patients. The LHW was identified as an indispensable link in the chain of efficient health care and therefore, specific educational guidelines on DM were generated to prepare her for the role. With her knowledge, insight into DM and the management thereof and newly required skills in educating and supporting of the patient, she could be an asset in the road to optimum self-care for the diabetic patient.
- Full Text:
- Date Issued: 2009
- Authors: De Mendonça, Hester Magdalena
- Date: 2009
- Subjects: Diabetics -- Treatment -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DCur
- Identifier: vital:10011 , http://hdl.handle.net/10948/1017 , Diabetics -- Treatment -- South Africa -- Eastern Cape
- Description: Diabetes Mellitus (DM) is the new epidemic in the world with 246 million people suffering from the disease at the moment and a projected increase to 380 million in 2025 (IDF, 2007b:36). The developing countries are the most vulnerable. Statistics state that SA and Egypt have the most diabetics on the continent. Globally, each year 3,8 million deaths are attributable to DM (IDF, 2007a). The Department of Health (DOH) and the Cacadu District Municipality (Eastern Cape) are serving a population of 102 721 in the Kouga and Koukamma areas, which covers an area of 5 992 km², with health care. There are 22 clinics with 28 registered nurses for all the clinics and between 3 and 9 lay health workers (LHWs) per clinic. For the purpose of this research study, the persons suffering from DM (±3550) in this area were taken into consideration (Strydom, 2005). DM is a chronic disorder and therefore patients should be able to manage their disease pattern for the rest of their lives (Healthline, 2008, Mbanya, 2006:12). In order to achieve this, continuous and effective patient education by health care providers are necessary. This disease affects more and more people each passing day, because of the rapid westernisation of the South African population, leading to more people attending clinics in the public health sector (Bonnici, 2002:32). There are specific guidelines laid down by the Department of Health (DOH) pertaining to the control and management of DM. Guidelines include the early diagnosis, treatment and patient education regarding DM (Department of Health, 1997, [revised 2004]). Evidence from previous research studies showed that not all registered nurses are aware of these guidelines and most have not been educated regarding the utilisation of these guidelines (O’Brien, van Rooyen & Carlson, 2006:36-40). In the clinics, the health care givers are confronted with a number of difficulties, such as a lack of funds to enable them to order adequate equipment and medicine. Another problem is the migration of registered nurses out of the country thus; there is also a shortage of staff to operate these clinics (Mkhize, 2004). The organisational structure in the clinics does not function optimally and there is a lack of communication between provincial, district and clinic level. Due to the above-mentioned challenges there is also a lack of efficient auditing systems to ensure quality assurance. Furthermore, a knowledge deficit pertaining to DM and the management thereof in all the groups participating in this study, namely the registered nurses, the lay health workers (LHWs) and the diabetic patients was found. The empowerment process of the LHW is not explored fully and therefore not executed to its full potential. To be able to improve the management of DM in this region, it is important to know what the difficulties are that the health care givers as well as the patients experience in relation to this issue. This study therefore explored and described these difficulties. The research was based on a qualitative, quantitative, explorative, descriptive and contextual research design. Health care givers as well as diabetic patients attending clinics in the Cacadu region of the Eastern Cape have been requested to complete questionnaires pertaining to their knowledge of Diabetes Mellitus. The current organisational structure of the provincial department of health was explored and findings analysed using the activities of the management process (Muller, 2006:106). The SA Government is committed to combining the national human resource development strategy with the rapid upgrading of service delivery to all of the nation’s communities. Stemming from this undertaking, suitable members of the community are to be trained as LHWs. LHWs are to play an integral role in strengthening the abilities of the community to empower themselves to participate and take responsibility for their own health and wellness (Department of Health, 2001a:4). From the research, it was found that the above-mentioned national plan had been implemented, but is not functioning at optimum level due to several shortcomings/deficits. Proposed guidelines were therefore designed to address the shortcomings and fragmentation of the plan. As specific knowledge deficits in DM were identified during this research study, general educational guidelines were included for the registered nurses and the diabetic patients. The LHW was identified as an indispensable link in the chain of efficient health care and therefore, specific educational guidelines on DM were generated to prepare her for the role. With her knowledge, insight into DM and the management thereof and newly required skills in educating and supporting of the patient, she could be an asset in the road to optimum self-care for the diabetic patient.
- Full Text:
- Date Issued: 2009
Hierarchical spatial structure and levels of resolution of intertidal grazing and their consequences on predictability and stability at small scales
- Authors: Diaz Diaz, Eliecer Rodrigo
- Date: 2009
- Subjects: Marine algae -- Effect of grazing on Shorelines -- South Africa Zostera marina Intertidal ecology Spatial analysis (Statistics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5707 , http://hdl.handle.net/10962/d1005393
- Description: The aim of this research was to assess three hierarchical aspects of alga-grazer interactions in intertidal communities on a small scale: spatial heterogeneity, grazing effects and spatial stability in grazing effects. First, using semivariograms and cross-semivariograms I observed hierarchical spatial patterns in most algal groups and in grazers. However, these patterns varied with the level on the shore and between shores, suggesting that either human exploitation or wave exposure can be a source of variability. Second, grazing effects were studied using manipulative experiments at different levels on the shore. These revealed significant effects of grazing on the low shore and in tidal pools. Additionally, using a transect of grazer exclusions across the shore, I observed unexpected hierarchical patchiness in the strength of grazing, rather than zonation in its effects. This patchiness varied in time due to different biotic and abiotic factors. In a separate experiment, the effect of mesograzers effects were studied in the upper eulittoral zone under four conditions: burnt open rock (BOR), burnt pools (Bpool), non-burnt open rock (NBOR) and non-burnt pools (NBpool). Additionally, I tested spatial stability in the effects of grazing in consecutive years, using the same plots. I observed great spatial variability in the effects of grazing, but this variability was spatially stable in Bpools and NBOR, meaning deterministic and significant grazing effects in consecutive years on the same plots. Both the significance in grazing effects and spatial stability depended on the level of resolution (species, functional, biomass) at which the algal assemblage was evaluated, suggesting hierarchical variability. In order to be able to predict spatial variability in the effects of grazers in the upper eulittoral zone using biotic and abiotic micro- and macrofactors, a conceptual model was proposed, based on data from several multiple-regressions. This linked the interactions among three elements: idiosyncratic heterogeneity, micro and macrofactors. This suggests that spatial variability can be a product of these factors, while spatial stability can be caused by the same or different combinations of factors. In conclusion, grazing and other ecological phenomena must be studied hierarchically, not only through spatiotemporal scales, but also at different levels of resolution, as these also influence our perception of patterns.
- Full Text:
- Date Issued: 2009
- Authors: Diaz Diaz, Eliecer Rodrigo
- Date: 2009
- Subjects: Marine algae -- Effect of grazing on Shorelines -- South Africa Zostera marina Intertidal ecology Spatial analysis (Statistics)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5707 , http://hdl.handle.net/10962/d1005393
- Description: The aim of this research was to assess three hierarchical aspects of alga-grazer interactions in intertidal communities on a small scale: spatial heterogeneity, grazing effects and spatial stability in grazing effects. First, using semivariograms and cross-semivariograms I observed hierarchical spatial patterns in most algal groups and in grazers. However, these patterns varied with the level on the shore and between shores, suggesting that either human exploitation or wave exposure can be a source of variability. Second, grazing effects were studied using manipulative experiments at different levels on the shore. These revealed significant effects of grazing on the low shore and in tidal pools. Additionally, using a transect of grazer exclusions across the shore, I observed unexpected hierarchical patchiness in the strength of grazing, rather than zonation in its effects. This patchiness varied in time due to different biotic and abiotic factors. In a separate experiment, the effect of mesograzers effects were studied in the upper eulittoral zone under four conditions: burnt open rock (BOR), burnt pools (Bpool), non-burnt open rock (NBOR) and non-burnt pools (NBpool). Additionally, I tested spatial stability in the effects of grazing in consecutive years, using the same plots. I observed great spatial variability in the effects of grazing, but this variability was spatially stable in Bpools and NBOR, meaning deterministic and significant grazing effects in consecutive years on the same plots. Both the significance in grazing effects and spatial stability depended on the level of resolution (species, functional, biomass) at which the algal assemblage was evaluated, suggesting hierarchical variability. In order to be able to predict spatial variability in the effects of grazers in the upper eulittoral zone using biotic and abiotic micro- and macrofactors, a conceptual model was proposed, based on data from several multiple-regressions. This linked the interactions among three elements: idiosyncratic heterogeneity, micro and macrofactors. This suggests that spatial variability can be a product of these factors, while spatial stability can be caused by the same or different combinations of factors. In conclusion, grazing and other ecological phenomena must be studied hierarchically, not only through spatiotemporal scales, but also at different levels of resolution, as these also influence our perception of patterns.
- Full Text:
- Date Issued: 2009
Immobilization of catalyst in a wall-coated micro-structured reactor for gas/liquid oxidation of p-cymene
- Authors: Makgwane, Peter Ramashadi
- Date: 2009
- Subjects: Oxidation , Cymene
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10389 , http://hdl.handle.net/10948/1182 , Oxidation , Cymene
- Description: The selective, liquid phase oxidation of p-cymene is an important synthetic route for the production of p-cresol via the tertiary cymene hydroperoxide (TCHP). The industrial-scale oxidation process is characterised by slow oxidation rates due to limitations in the mass transfer of oxidant (gaseous oxygen) into the liquid phase. However, like all other autoxidation reactions, the oxidation reaction is exothermic, following the typical free radical autoxidation reaction mechanism, which implies that careful temperature control is critical in order to prevent the further reaction of the initially formed hydroperoxide species. In the presence of metal catalysts, the limiting oxidation rate is the transfer of oxygen from the gas to liquid boundary interface. As a result, low product yields and poor productivity space-time yield are typically experienced. At high substrate conversions, by-products resulting from the decomposition of the formed hydroperoxides predominate. For this reason, the conversion of substrate is restricted to preserve the TCHP selectivity. The slow rates in industrial-scale p-cymene oxidations results in long oxidation times, typically 8-12 h. Substrate conversions are typically between 15-20 percent, and the TCHP selectivity ranges between 65-70 percent. The work described in this thesis concerns the oxidation of p-cymene in a microstructured falling film reactor (FFMSR). These reactor systems facilitate chemical reactors to have high mass and heat transfer rates because of high surface area-to-volume ratios. Due to their small internal volumes, these reactors are inherently safe to operate. These properties were exploited to improve the p-cymene oxidation rate and, consequently, the space-time yield. In order to evaluate the suitability of vanadium phosphate oxide (VPO) catalysts for use as supported catalyst in the FFMSR, different catalysts prepared from VOHPO4∙0.5H2O and VO(H2PO4)2 precursors was first evaluated for the oxidation of p-cymene in a well-stirred batch reactor. The results of the two activated catalysts, (VO)2P2O7 and VO(PO3)2 when used as powders in their pure form, showed a significant improvement in p-cymene oxidation rates with conversions up to 40 percent in 3-4 h reaction time with a TCHP selectivity of 75-80 percent. The (VO)2P2O7 catalyst showed better oxidation rates and selectivity when compared to the VO(PO3)2 catalyst obtained from the VO(H2PO4)2 precursor. The (VO)2P2O7 catalyst was supported on a stainless steel plate and the coated plate used to study the long-term stability and catalytic perfornance of the catalyst during p-cymene oxidations in a batch reactor. Comparable oxidation rates and TCHP selectivity were obtained with the stainless steel coated VPO catalyst when compared to the “free powder” (VO)2P2O7 catalyst. The results also showed that the stainless steel coated catalyst displays a slow, yet significant deactivation over extended reaction periods (250 h onstream). Characterization of the exposed (VO)2P2O7 catalyst to p-cymene oxidation conditions by powder XRD, SEM and TGA-MS showed that (VO)2P2O7 phase undergoes structural transformation back to VOHPO4∙0.5H2O phase over time. The (VO)2P2O7/-Al2O3 catalyst was used to coat the micro-channel reaction plates of the FFMSR. Both uncoated and coated micro-channel reaction plates were evaluated in the FFMSR for the oxidation of p-cymene. The FFMSR showed effective improvement of oxidation rates in terms of productivity space-time-yield at comparable batch p-cymene conversions. A Typical 10 percent conversion in catalysed batch oxidations at 1-2 h reaction time was achieved in few seconds (19 s) reaction time in FFMSR. The comparison of uncoated (i.e. uncatalysed) and coated (i.e. catalysed) FFMSR oxidations showed slight differences in oxidation rates. No clear explanation could be established with the present results for the observed same behaviour. However, the insufficient contact time between the gas and liquid reactants with the wall-coated solid catalyst is one of the possible causes for the observed behaviour of the coated and uncoated micro-channel plates. A simple developed kinetic model was used to confirm the obtained batch oxidation results using cumene as probe compound due to its similarity to p-cumene oxidation and extensive studied kinetics. With the estimated K values and available rate constants from literature, it was possible to predict the conversions in a batch reactor at the same typical micro-structured reactor residence time (i.e. of 19 s). The predicted conversions in the batch reactor were less than 0.1 percent even at harsh conditions such as 170 oC when compared to about 10 percent achieved in the micro-structured reactor at the same reaction temperature, reactants concentration and reaction time of 19 s. This difference in the reactor systems performance indicates the unique advantages offered by micro-structured reactors (e.g. improved mass transfer, temperature management and high surface-to-volume ratios) to perform typical gas/liquid mass transfer limited reactions such as cumene and p-cymene autoxidations.
- Full Text:
- Date Issued: 2009
- Authors: Makgwane, Peter Ramashadi
- Date: 2009
- Subjects: Oxidation , Cymene
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10389 , http://hdl.handle.net/10948/1182 , Oxidation , Cymene
- Description: The selective, liquid phase oxidation of p-cymene is an important synthetic route for the production of p-cresol via the tertiary cymene hydroperoxide (TCHP). The industrial-scale oxidation process is characterised by slow oxidation rates due to limitations in the mass transfer of oxidant (gaseous oxygen) into the liquid phase. However, like all other autoxidation reactions, the oxidation reaction is exothermic, following the typical free radical autoxidation reaction mechanism, which implies that careful temperature control is critical in order to prevent the further reaction of the initially formed hydroperoxide species. In the presence of metal catalysts, the limiting oxidation rate is the transfer of oxygen from the gas to liquid boundary interface. As a result, low product yields and poor productivity space-time yield are typically experienced. At high substrate conversions, by-products resulting from the decomposition of the formed hydroperoxides predominate. For this reason, the conversion of substrate is restricted to preserve the TCHP selectivity. The slow rates in industrial-scale p-cymene oxidations results in long oxidation times, typically 8-12 h. Substrate conversions are typically between 15-20 percent, and the TCHP selectivity ranges between 65-70 percent. The work described in this thesis concerns the oxidation of p-cymene in a microstructured falling film reactor (FFMSR). These reactor systems facilitate chemical reactors to have high mass and heat transfer rates because of high surface area-to-volume ratios. Due to their small internal volumes, these reactors are inherently safe to operate. These properties were exploited to improve the p-cymene oxidation rate and, consequently, the space-time yield. In order to evaluate the suitability of vanadium phosphate oxide (VPO) catalysts for use as supported catalyst in the FFMSR, different catalysts prepared from VOHPO4∙0.5H2O and VO(H2PO4)2 precursors was first evaluated for the oxidation of p-cymene in a well-stirred batch reactor. The results of the two activated catalysts, (VO)2P2O7 and VO(PO3)2 when used as powders in their pure form, showed a significant improvement in p-cymene oxidation rates with conversions up to 40 percent in 3-4 h reaction time with a TCHP selectivity of 75-80 percent. The (VO)2P2O7 catalyst showed better oxidation rates and selectivity when compared to the VO(PO3)2 catalyst obtained from the VO(H2PO4)2 precursor. The (VO)2P2O7 catalyst was supported on a stainless steel plate and the coated plate used to study the long-term stability and catalytic perfornance of the catalyst during p-cymene oxidations in a batch reactor. Comparable oxidation rates and TCHP selectivity were obtained with the stainless steel coated VPO catalyst when compared to the “free powder” (VO)2P2O7 catalyst. The results also showed that the stainless steel coated catalyst displays a slow, yet significant deactivation over extended reaction periods (250 h onstream). Characterization of the exposed (VO)2P2O7 catalyst to p-cymene oxidation conditions by powder XRD, SEM and TGA-MS showed that (VO)2P2O7 phase undergoes structural transformation back to VOHPO4∙0.5H2O phase over time. The (VO)2P2O7/-Al2O3 catalyst was used to coat the micro-channel reaction plates of the FFMSR. Both uncoated and coated micro-channel reaction plates were evaluated in the FFMSR for the oxidation of p-cymene. The FFMSR showed effective improvement of oxidation rates in terms of productivity space-time-yield at comparable batch p-cymene conversions. A Typical 10 percent conversion in catalysed batch oxidations at 1-2 h reaction time was achieved in few seconds (19 s) reaction time in FFMSR. The comparison of uncoated (i.e. uncatalysed) and coated (i.e. catalysed) FFMSR oxidations showed slight differences in oxidation rates. No clear explanation could be established with the present results for the observed same behaviour. However, the insufficient contact time between the gas and liquid reactants with the wall-coated solid catalyst is one of the possible causes for the observed behaviour of the coated and uncoated micro-channel plates. A simple developed kinetic model was used to confirm the obtained batch oxidation results using cumene as probe compound due to its similarity to p-cumene oxidation and extensive studied kinetics. With the estimated K values and available rate constants from literature, it was possible to predict the conversions in a batch reactor at the same typical micro-structured reactor residence time (i.e. of 19 s). The predicted conversions in the batch reactor were less than 0.1 percent even at harsh conditions such as 170 oC when compared to about 10 percent achieved in the micro-structured reactor at the same reaction temperature, reactants concentration and reaction time of 19 s. This difference in the reactor systems performance indicates the unique advantages offered by micro-structured reactors (e.g. improved mass transfer, temperature management and high surface-to-volume ratios) to perform typical gas/liquid mass transfer limited reactions such as cumene and p-cymene autoxidations.
- Full Text:
- Date Issued: 2009
Implementation of a 150kva biomass gasifier system for community economic empowerment in South Africa
- Mamphweli, Ntshengedzeni Sampson
- Authors: Mamphweli, Ntshengedzeni Sampson
- Date: 2009
- Subjects: Rural development -- South Africa , Electric power distribution -- South Africa , Condensation , Rural electrification -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11591 , http://hdl.handle.net/10353/262 , Rural development -- South Africa , Electric power distribution -- South Africa , Condensation , Rural electrification -- South Africa
- Description: There is growing interest in research and development activities on biomass gasification technologies as an alternative to fossil fuels technologies. However not much has been done in terms of technology transfer, particularly in under-developed and developing countries such as South Africa. This is mainly because of the lack of resources such as funding. Most parts of the under-developed and developing countries fall within rural areas and semi-urban centers, which are endowed with biomass resources. South Africa has a number of sawmill operators who generate tons of biomass waste during processing of timber; the large proportion of this is burned in furnaces as a means for waste management while a very small proportion is collected and used by people in rural areas for cooking their food. The majority of people in rural areas of South Africa are either unemployed or cannot afford the current energy services. The main aim of this research was to establish the viability of electricity generation for community economic development through biomass gasification, specifically using the locally designed System Johansson Biomass Gasifier™ (SJBG), and to establish the efficiency of the gasifier and associated components with a view of developing strategies to enhance it. The study established the technical and economic feasibility of using the SJBG to generate low-cost electricity for community empowerment. The study also developed strategies to improve the particle collection efficiency of the cyclone. In addition to this, a low-cost gas and temperature monitoring system capable of monitoring gas and temperature at various points of the gasifier was developed. The system was built from three Non- Dispersive Infrared gas sensors, one Palladium/Nickel gas sensor and four type K thermocouples. The study also investigated the impact of fuel compartment condensates on gasifier conversion efficiency. This is an area that has not yet been well researched since much has been done on energy recovery using combined heat and power applications that do not utilize the energy in condensates because these are produced in the gasifier and drained with chemical energy stored in them. The study established that the condensates do not have a significant impact on efficiency.
- Full Text:
- Date Issued: 2009
- Authors: Mamphweli, Ntshengedzeni Sampson
- Date: 2009
- Subjects: Rural development -- South Africa , Electric power distribution -- South Africa , Condensation , Rural electrification -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11591 , http://hdl.handle.net/10353/262 , Rural development -- South Africa , Electric power distribution -- South Africa , Condensation , Rural electrification -- South Africa
- Description: There is growing interest in research and development activities on biomass gasification technologies as an alternative to fossil fuels technologies. However not much has been done in terms of technology transfer, particularly in under-developed and developing countries such as South Africa. This is mainly because of the lack of resources such as funding. Most parts of the under-developed and developing countries fall within rural areas and semi-urban centers, which are endowed with biomass resources. South Africa has a number of sawmill operators who generate tons of biomass waste during processing of timber; the large proportion of this is burned in furnaces as a means for waste management while a very small proportion is collected and used by people in rural areas for cooking their food. The majority of people in rural areas of South Africa are either unemployed or cannot afford the current energy services. The main aim of this research was to establish the viability of electricity generation for community economic development through biomass gasification, specifically using the locally designed System Johansson Biomass Gasifier™ (SJBG), and to establish the efficiency of the gasifier and associated components with a view of developing strategies to enhance it. The study established the technical and economic feasibility of using the SJBG to generate low-cost electricity for community empowerment. The study also developed strategies to improve the particle collection efficiency of the cyclone. In addition to this, a low-cost gas and temperature monitoring system capable of monitoring gas and temperature at various points of the gasifier was developed. The system was built from three Non- Dispersive Infrared gas sensors, one Palladium/Nickel gas sensor and four type K thermocouples. The study also investigated the impact of fuel compartment condensates on gasifier conversion efficiency. This is an area that has not yet been well researched since much has been done on energy recovery using combined heat and power applications that do not utilize the energy in condensates because these are produced in the gasifier and drained with chemical energy stored in them. The study established that the condensates do not have a significant impact on efficiency.
- Full Text:
- Date Issued: 2009
Indigenous knowledges: a genealogy of representations and applications in developing contexts of environmental education and development in southern Africa
- Authors: Shava, Soul
- Date: 2009
- Subjects: Foucault, Michel, 1926-1984 Education -- Africa, Southern Environmental education -- Africa, Southern Indigenous peoples -- Africa, Southern Ethnoscience -- Africa, Southern Knowledge, Theory of Genealogy (Philosophy) Medicinal plants -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1885 , http://hdl.handle.net/10962/d1005920
- Description: This study was developed around concerns about how indigenous knowledges have been represented and applied in environment and development education. The first phase of the study is a genealogical analysis after Michel Foucault. This probes representations and applications of plant-based indigenous knowledge in selected anthropological, botanical and environmental education texts in southern Africa. The emerging insights were deepened using a Social (Critical) Realism vantage point after Margaret Archer to shed light on agential issues in environmental education and development contexts. Here her morphogenetic/morphostatic analysis of social transformation or reproduction is used to trace changes in indigenous knowledge representations and applications over time (from the pre-colonial into the post-colonial era). The second phase uses the same perspectives and tools to extend the analysis of power/knowledge relationships into the interface of indigenous communities and modern institutions in two case study settings in the Eastern Cape of South Africa. This study reveals colonially-derived hegemonic processes of modern/Western scientific institutional representations/interpretations of the knowledges of indigenous communities. It also tracks a continuing trajectory of their dominating and prescriptive mediating control over local knowledges from the pre-colonial context through into the post-colonial period in southern Africa. The analysis reveals how this hegemony is sustained through the deployment of institutional strategies of representation that transform local knowledges into the disciplinary knowledge discourses of modern scientific institutions. These representational strategies therefore generate/reproduce and validate disciplinary discourses about the other, constructing disciplinary 'regimes of truth'. In this way modern institutions appropriate and displace indigenous/local knowledges, silence the voices of local communities and regulate individual and community agency within a continuing subjugation of indigenous knowledges. This study reveals how working within modern institutions and disciplinary knowledges in participative education and development interactions can serve to implicate indigenous researchers in these institutional hegemonic processes. The study also notes evidence of a continued resistance to hegemonic Western knowledge discourses as indigenous communities have sustained many knowledge practices alongside Western knowledge discourses. There is also evidence of a recent emergence of counter-hegemonic indigenous knowledge discourses in environmental education and development practices in southern Africa. It is noted that these have been contingent upon the changing political terrain in southern Africa as this has opened the way for alternative discourses to the dominant conventional Western knowledges in formal education and development contexts. The counterhegemonic discourses invert power/knowledge relations, decentre hegemonic discourses and reposition indigenous knowledges in formal education and development contexts. This study suggests the need to foreground indigenous knowledges as a process of knowledge decolonisation that gives contextual and epistemic relevance to environmental education and development processes. This calls for a need for new strategies to transform existing institutions by creating enabling spaces for the representational inclusion of indigenous knowledges in formal/conventional knowledge discourses and their application in social contexts. This opens up possibilities for plural knowledge representations and for their integrative and reciprocal co-engagement in situated contexts of environmental education and development in southern Africa.
- Full Text:
- Date Issued: 2009
- Authors: Shava, Soul
- Date: 2009
- Subjects: Foucault, Michel, 1926-1984 Education -- Africa, Southern Environmental education -- Africa, Southern Indigenous peoples -- Africa, Southern Ethnoscience -- Africa, Southern Knowledge, Theory of Genealogy (Philosophy) Medicinal plants -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1885 , http://hdl.handle.net/10962/d1005920
- Description: This study was developed around concerns about how indigenous knowledges have been represented and applied in environment and development education. The first phase of the study is a genealogical analysis after Michel Foucault. This probes representations and applications of plant-based indigenous knowledge in selected anthropological, botanical and environmental education texts in southern Africa. The emerging insights were deepened using a Social (Critical) Realism vantage point after Margaret Archer to shed light on agential issues in environmental education and development contexts. Here her morphogenetic/morphostatic analysis of social transformation or reproduction is used to trace changes in indigenous knowledge representations and applications over time (from the pre-colonial into the post-colonial era). The second phase uses the same perspectives and tools to extend the analysis of power/knowledge relationships into the interface of indigenous communities and modern institutions in two case study settings in the Eastern Cape of South Africa. This study reveals colonially-derived hegemonic processes of modern/Western scientific institutional representations/interpretations of the knowledges of indigenous communities. It also tracks a continuing trajectory of their dominating and prescriptive mediating control over local knowledges from the pre-colonial context through into the post-colonial period in southern Africa. The analysis reveals how this hegemony is sustained through the deployment of institutional strategies of representation that transform local knowledges into the disciplinary knowledge discourses of modern scientific institutions. These representational strategies therefore generate/reproduce and validate disciplinary discourses about the other, constructing disciplinary 'regimes of truth'. In this way modern institutions appropriate and displace indigenous/local knowledges, silence the voices of local communities and regulate individual and community agency within a continuing subjugation of indigenous knowledges. This study reveals how working within modern institutions and disciplinary knowledges in participative education and development interactions can serve to implicate indigenous researchers in these institutional hegemonic processes. The study also notes evidence of a continued resistance to hegemonic Western knowledge discourses as indigenous communities have sustained many knowledge practices alongside Western knowledge discourses. There is also evidence of a recent emergence of counter-hegemonic indigenous knowledge discourses in environmental education and development practices in southern Africa. It is noted that these have been contingent upon the changing political terrain in southern Africa as this has opened the way for alternative discourses to the dominant conventional Western knowledges in formal education and development contexts. The counterhegemonic discourses invert power/knowledge relations, decentre hegemonic discourses and reposition indigenous knowledges in formal education and development contexts. This study suggests the need to foreground indigenous knowledges as a process of knowledge decolonisation that gives contextual and epistemic relevance to environmental education and development processes. This calls for a need for new strategies to transform existing institutions by creating enabling spaces for the representational inclusion of indigenous knowledges in formal/conventional knowledge discourses and their application in social contexts. This opens up possibilities for plural knowledge representations and for their integrative and reciprocal co-engagement in situated contexts of environmental education and development in southern Africa.
- Full Text:
- Date Issued: 2009
Insect pests of cultivated and wild olives, and some of their natural enemies, in the Eastern Cape, South Africa
- Authors: Mkize, Nolwazi
- Date: 2009
- Subjects: Pests -- Control -- South Africa -- Eastern Cape Olive -- Diseases and pests -- South Africa -- Eastern Cape Agriculture -- South Africa -- Eastern Cape Fruit-flies -- South Africa -- Eastern Cape Tephritidae Flea beetles Lace bugs
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5717 , http://hdl.handle.net/10962/d1005403
- Description: This thesis has two focuses. The first problem facing the olive industry in the Eastern Cape is the growers’ perceptions of both what the industry will provide them and what a pest management program might entail. The second focus is the biology of olive pests in the Eastern Cape in terms of understanding their populations and their natural enemies on private farms, with future hopes of understanding how Integrated Pest Management strategies can be developed for this crop. Eastern Cape private farmers, small-scale farmers and workers from agricultural training institutions were interviewed regarding the history and cultivation of the local olive crop. Only one commercially viable olive grove was identified; other groves were small, experimental pilot ventures. The introduction of olives to small-scale farmers and agricultural training schools was generally a top-down initiative that led to a lack of sense of ownership and the trees being neglected. Other problems included poor human capital; poor financial capital; lack of adequate support; lack of knowledge transfer and stability; lack of communication and evaluation procedures of the project; miscommunication; and finally, olive pests. Apart from hesitancy to plant at a commercial scale, the main problem facing private farmers (Varnam Farm, Hewlands Farm and Springvale Farm) was pests. Therefore an investigation of pests from private farms was conducted ranging from collection of cultivated and wild olive fruit and flea beetle larvae for parasitism, trapping systems both for fruit flies and olive flea beetle adults. A survey of olive fruits yielded larval fruit flies of the families Tephritidae (Bactrocera oleae (Rossi), B. biguttula (Bezzi) and Ceratitis capitata (Wiedemann)) and Drosophilidae (Drosophila melanogaster (Meigen)) from wild olives (O. europaea cuspidata (Wall. ex G. Don) Cif.) but none from cultivated olives (O. e. europaea L.). Braconid wasps (Opiinae and Braconinae) were reared only from fruits containing B. oleae and B. biguttula. This suggests that B. oleae is not of economic significance in the Eastern Cape, perhaps because it is controlled to a significant level by natural enemies, but B. biguttula may be a potential economic pest. A survey of adult fruit flies using ChamP traps baited with ammonium bicarbonate and spiroketal capsules and Sensus trap baited with methyl eugenol and Questlure confirmed the relative importance of B. biguttula over B. oleae. ChamP traps were over 50 times better than Sensus traps for mass trapping of B. biguttula but both were ineffective for trapping B. oleae and C. capitata. Six indigenous flea beetles of the genus Argopistes Motschulsky (Chrysomelidae: Alticinae) were found, three described by Bryant in 1922 and 1944 and three new species. Their morphology was investigated by scanning electron microscopy and mutivariate morphometric analysis. The leaf-mining larvae are pests of wild and cultivated olives in South Africa and threaten the local olive industry. At Springvale Farm, A. oleae Bryant and A. sexvittatus Bryant preferred the upper parts of trees, near new leaves. Pseudophanomeris inopinatus (Blkb.) (Braconidae) was reared from 23 Argopistes larvae. The beetle larvae might not be controlled to a significant level by natural enemies because the rate of parasitism was low. The olive flea beetles showed no attraction to traps containing various volatile compounds as baits. The lace bug, Plerochila australis Distant (Tingidae), was sometimes a pest. It showed a preference for the underside of leaves on the lower parts of the trees. A moth, Palpita unionalis Hübner (Crambidae), was reared in very low numbers and without parasitoids. A twig-boring beetle larva, chalcidoid parasitoids and seed wasps of the families Eurytomidae, Ormyridae and Eupelmidae were also recorded.
- Full Text:
- Date Issued: 2009
- Authors: Mkize, Nolwazi
- Date: 2009
- Subjects: Pests -- Control -- South Africa -- Eastern Cape Olive -- Diseases and pests -- South Africa -- Eastern Cape Agriculture -- South Africa -- Eastern Cape Fruit-flies -- South Africa -- Eastern Cape Tephritidae Flea beetles Lace bugs
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5717 , http://hdl.handle.net/10962/d1005403
- Description: This thesis has two focuses. The first problem facing the olive industry in the Eastern Cape is the growers’ perceptions of both what the industry will provide them and what a pest management program might entail. The second focus is the biology of olive pests in the Eastern Cape in terms of understanding their populations and their natural enemies on private farms, with future hopes of understanding how Integrated Pest Management strategies can be developed for this crop. Eastern Cape private farmers, small-scale farmers and workers from agricultural training institutions were interviewed regarding the history and cultivation of the local olive crop. Only one commercially viable olive grove was identified; other groves were small, experimental pilot ventures. The introduction of olives to small-scale farmers and agricultural training schools was generally a top-down initiative that led to a lack of sense of ownership and the trees being neglected. Other problems included poor human capital; poor financial capital; lack of adequate support; lack of knowledge transfer and stability; lack of communication and evaluation procedures of the project; miscommunication; and finally, olive pests. Apart from hesitancy to plant at a commercial scale, the main problem facing private farmers (Varnam Farm, Hewlands Farm and Springvale Farm) was pests. Therefore an investigation of pests from private farms was conducted ranging from collection of cultivated and wild olive fruit and flea beetle larvae for parasitism, trapping systems both for fruit flies and olive flea beetle adults. A survey of olive fruits yielded larval fruit flies of the families Tephritidae (Bactrocera oleae (Rossi), B. biguttula (Bezzi) and Ceratitis capitata (Wiedemann)) and Drosophilidae (Drosophila melanogaster (Meigen)) from wild olives (O. europaea cuspidata (Wall. ex G. Don) Cif.) but none from cultivated olives (O. e. europaea L.). Braconid wasps (Opiinae and Braconinae) were reared only from fruits containing B. oleae and B. biguttula. This suggests that B. oleae is not of economic significance in the Eastern Cape, perhaps because it is controlled to a significant level by natural enemies, but B. biguttula may be a potential economic pest. A survey of adult fruit flies using ChamP traps baited with ammonium bicarbonate and spiroketal capsules and Sensus trap baited with methyl eugenol and Questlure confirmed the relative importance of B. biguttula over B. oleae. ChamP traps were over 50 times better than Sensus traps for mass trapping of B. biguttula but both were ineffective for trapping B. oleae and C. capitata. Six indigenous flea beetles of the genus Argopistes Motschulsky (Chrysomelidae: Alticinae) were found, three described by Bryant in 1922 and 1944 and three new species. Their morphology was investigated by scanning electron microscopy and mutivariate morphometric analysis. The leaf-mining larvae are pests of wild and cultivated olives in South Africa and threaten the local olive industry. At Springvale Farm, A. oleae Bryant and A. sexvittatus Bryant preferred the upper parts of trees, near new leaves. Pseudophanomeris inopinatus (Blkb.) (Braconidae) was reared from 23 Argopistes larvae. The beetle larvae might not be controlled to a significant level by natural enemies because the rate of parasitism was low. The olive flea beetles showed no attraction to traps containing various volatile compounds as baits. The lace bug, Plerochila australis Distant (Tingidae), was sometimes a pest. It showed a preference for the underside of leaves on the lower parts of the trees. A moth, Palpita unionalis Hübner (Crambidae), was reared in very low numbers and without parasitoids. A twig-boring beetle larva, chalcidoid parasitoids and seed wasps of the families Eurytomidae, Ormyridae and Eupelmidae were also recorded.
- Full Text:
- Date Issued: 2009
Investigation of device and performance parameters of photovoltaic devices
- Macabebe, Erees Queen Barrido
- Authors: Macabebe, Erees Queen Barrido
- Date: 2009
- Subjects: Photovoltaic cells , Solar cells , Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10538 , http://hdl.handle.net/10948/1003 , http://hdl.handle.net/10948/d1012890 , Photovoltaic cells , Solar cells , Photovoltaic power systems , Photovoltaic power generation
- Description: In order to investigate the influence of parasitic resistances, saturation current and diode ideality factor on the performance of photovoltaic devices, parameter extraction routines employing the standard iteration (SI) method and the particle swarm optimization (PSO) method were developed to extract the series resistance, shunt resistance, saturation current and ideality factor from the I-V characteristics of solar cells and PV modules. The well-known one- and two-diode models were used to describe the behavior of the I-V curve and the parameters of the models were determined by approximation and iteration techniques. The SI and the PSO extraction programmes were used to assess the suitability of the one- and the two-diode solar cell models in describing the I-V characteristics of mono- and multicrystalline silicon solar cells, CISS- and CIGSS-based solar cells. This exercise revealed that the two-diode model provides more information regarding the different processes involved in solar cell operation. Between the two methods developed, the PSO method is faster, yielded fitted curves with lower standard deviation of residuals and, therefore, was the preferred extraction method. The PSO method was then used to extract the device parameters of CISS-based solar cells with the CISS layer selenized under different selenization process conditions and CIGSS-based solar cells with varying i-ZnO layer thickness. For the CISS-based solar cells, the detrimental effect of parasitic resistances on device performance increased when the temperature and duration of the selenization process was increased. For the CIGSS-based devices, photogeneration improved with increasing i-ZnO layer thickness. At high forward bias, bulk recombination and/or tunneling-assisted recombination were the dominant processes affecting the I-V characteristics of the devices. v Lastly, device and performance parameters of mono-, multicrystalline silicon and CIS modules derived from I-V characteristics obtained under dark and illuminated conditions were analyzed considering the effects of temperature on the performance of the devices. Results showed that the effects of parasitic resistances are greater under illumination and, under outdoor conditions, the values further declined due to increasing temperature. The saturation current and ideality factor also increased under outdoor conditions which suggest increased recombination and, coupled with the adverse effects of parasitic resistances, these factors result in lower FF and lower maximum power point. Analysis performed on crystalline silicon and thin film devices utilized in this study revealed that parameter extraction from I-V characteristics of photovoltaic devices and, in particular, the implementation of PSO in solar cell device parameter extraction developed in this work is a useful characterization technique.
- Full Text:
- Date Issued: 2009
- Authors: Macabebe, Erees Queen Barrido
- Date: 2009
- Subjects: Photovoltaic cells , Solar cells , Photovoltaic power systems , Photovoltaic power generation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10538 , http://hdl.handle.net/10948/1003 , http://hdl.handle.net/10948/d1012890 , Photovoltaic cells , Solar cells , Photovoltaic power systems , Photovoltaic power generation
- Description: In order to investigate the influence of parasitic resistances, saturation current and diode ideality factor on the performance of photovoltaic devices, parameter extraction routines employing the standard iteration (SI) method and the particle swarm optimization (PSO) method were developed to extract the series resistance, shunt resistance, saturation current and ideality factor from the I-V characteristics of solar cells and PV modules. The well-known one- and two-diode models were used to describe the behavior of the I-V curve and the parameters of the models were determined by approximation and iteration techniques. The SI and the PSO extraction programmes were used to assess the suitability of the one- and the two-diode solar cell models in describing the I-V characteristics of mono- and multicrystalline silicon solar cells, CISS- and CIGSS-based solar cells. This exercise revealed that the two-diode model provides more information regarding the different processes involved in solar cell operation. Between the two methods developed, the PSO method is faster, yielded fitted curves with lower standard deviation of residuals and, therefore, was the preferred extraction method. The PSO method was then used to extract the device parameters of CISS-based solar cells with the CISS layer selenized under different selenization process conditions and CIGSS-based solar cells with varying i-ZnO layer thickness. For the CISS-based solar cells, the detrimental effect of parasitic resistances on device performance increased when the temperature and duration of the selenization process was increased. For the CIGSS-based devices, photogeneration improved with increasing i-ZnO layer thickness. At high forward bias, bulk recombination and/or tunneling-assisted recombination were the dominant processes affecting the I-V characteristics of the devices. v Lastly, device and performance parameters of mono-, multicrystalline silicon and CIS modules derived from I-V characteristics obtained under dark and illuminated conditions were analyzed considering the effects of temperature on the performance of the devices. Results showed that the effects of parasitic resistances are greater under illumination and, under outdoor conditions, the values further declined due to increasing temperature. The saturation current and ideality factor also increased under outdoor conditions which suggest increased recombination and, coupled with the adverse effects of parasitic resistances, these factors result in lower FF and lower maximum power point. Analysis performed on crystalline silicon and thin film devices utilized in this study revealed that parameter extraction from I-V characteristics of photovoltaic devices and, in particular, the implementation of PSO in solar cell device parameter extraction developed in this work is a useful characterization technique.
- Full Text:
- Date Issued: 2009
Lead-radium dating of two deep-water fishes from the southern hemisphere, Patagonian toothfish (Dissostichus eleginoides) and Orange Roughy (Hoplostethus atlanticus)
- Authors: Andrews, Allen Hia
- Date: 2009
- Subjects: Fishes -- Age determination , Fishes -- Southern hemisphere -- Longevity , Fishes -- Growth , Radioactive dating , Patagonian toothfish , Patagonian toothfish -- Fisheries , Orange roughy , Orange roughy -- Fisheries , Deep-sea fishes -- Southern hemisphere , Deep-sea fisheries , Deep-sea fisheries -- Southern hemisphere
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5295 , http://hdl.handle.net/10962/d1005140
- Description: Patagonian toothfish (Dissostichus eleginoides) or "Chilean sea bass" support a valuable and controversial fishery, but the life history is little known and longevity estimates range from ~20 to more than 40 or 50 yr. In this study, lead-radium dating provided validated age estimates from juveniles to older adults, supporting the use of otoliths as accurate indicators of age. The oldest age groups were near 30 yr, which provided support for age estimates exceeding 40 or 50 yr from grow zone counts in otolith sections. Hence, scale reading, which rarely exceeds 20 years, has the potential for age underestimation. Lead-radium dating revealed what may be minor differences in age interpretation between two facilities and findings may provide an age-validated opportunity for the CCAMLR Otolith Network to reassess otolith interpretations. Orange roughy (Hoplostethus atlanticus) support a major deep-sea fishery and stock assessments often depend on age analyses, but lifespan estimates range from ~20 to over 100 yr and validation of growth zone counts remained unresolved. An early application of lead-radium dating supported centenarian ages, but the findings were met with disbelief and some studies have attempted to discredit the technique and the long lifespan. In this study, an improved lead-radium dating technique used smaller samples than previously possible and circumvented assumptions that were previously necessary. Lead-radium dating of otolith cores, the first few years of growth, provided ratios that correlated well with the ingrowth curve. This provided robust support for age estimates from otolith thin sections. Use of radiometric ages as independent age estimates indicated the fish in the oldest group were at least 93 yr. Lead-radium dating has validated a centenarian lifespan for orange roughy. To date, radium-226 has been measured in otoliths of 39 fish species ranging from the northern Pacific and Atlantic Oceans to the Southern Ocean. In total, 367 reliable radium-226 measurements were made in 36 studies since the first lead-radium dating study on fish in 1982. The activity of radium-226 measurements ranged over 3 orders of magnitude (<0.001 to >1.0 dpm.g⁻¹). An analysis revealed ontogenetic differences in radium-226 uptake that may be attributed to changes in habitat or diet. Radiometric age from otolith core studies was used to describe a radium-226 uptake time-series for some species, which revealed interesting patterns over long periods. This synopsis provides information on the uptake of radium-226 to otoliths from an environmental perspective, which can be used as a basis for future studies.
- Full Text:
- Date Issued: 2009
- Authors: Andrews, Allen Hia
- Date: 2009
- Subjects: Fishes -- Age determination , Fishes -- Southern hemisphere -- Longevity , Fishes -- Growth , Radioactive dating , Patagonian toothfish , Patagonian toothfish -- Fisheries , Orange roughy , Orange roughy -- Fisheries , Deep-sea fishes -- Southern hemisphere , Deep-sea fisheries , Deep-sea fisheries -- Southern hemisphere
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5295 , http://hdl.handle.net/10962/d1005140
- Description: Patagonian toothfish (Dissostichus eleginoides) or "Chilean sea bass" support a valuable and controversial fishery, but the life history is little known and longevity estimates range from ~20 to more than 40 or 50 yr. In this study, lead-radium dating provided validated age estimates from juveniles to older adults, supporting the use of otoliths as accurate indicators of age. The oldest age groups were near 30 yr, which provided support for age estimates exceeding 40 or 50 yr from grow zone counts in otolith sections. Hence, scale reading, which rarely exceeds 20 years, has the potential for age underestimation. Lead-radium dating revealed what may be minor differences in age interpretation between two facilities and findings may provide an age-validated opportunity for the CCAMLR Otolith Network to reassess otolith interpretations. Orange roughy (Hoplostethus atlanticus) support a major deep-sea fishery and stock assessments often depend on age analyses, but lifespan estimates range from ~20 to over 100 yr and validation of growth zone counts remained unresolved. An early application of lead-radium dating supported centenarian ages, but the findings were met with disbelief and some studies have attempted to discredit the technique and the long lifespan. In this study, an improved lead-radium dating technique used smaller samples than previously possible and circumvented assumptions that were previously necessary. Lead-radium dating of otolith cores, the first few years of growth, provided ratios that correlated well with the ingrowth curve. This provided robust support for age estimates from otolith thin sections. Use of radiometric ages as independent age estimates indicated the fish in the oldest group were at least 93 yr. Lead-radium dating has validated a centenarian lifespan for orange roughy. To date, radium-226 has been measured in otoliths of 39 fish species ranging from the northern Pacific and Atlantic Oceans to the Southern Ocean. In total, 367 reliable radium-226 measurements were made in 36 studies since the first lead-radium dating study on fish in 1982. The activity of radium-226 measurements ranged over 3 orders of magnitude (<0.001 to >1.0 dpm.g⁻¹). An analysis revealed ontogenetic differences in radium-226 uptake that may be attributed to changes in habitat or diet. Radiometric age from otolith core studies was used to describe a radium-226 uptake time-series for some species, which revealed interesting patterns over long periods. This synopsis provides information on the uptake of radium-226 to otoliths from an environmental perspective, which can be used as a basis for future studies.
- Full Text:
- Date Issued: 2009
Learning, governance and livelihoods : toward adaptive co-management under resource poor conditions in South Africa
- Authors: Cundill, Georgina
- Date: 2009
- Subjects: Natural resources -- Co-management -- South Africa Rural poor -- South Africa Rural development -- South Africa Households -- Economic aspects -- South Africa Sustainable development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4747 , http://hdl.handle.net/10962/d1006961
- Description: Through collaborative monitoring and case study comparison, this thesis explores conceptual and methodological approaches to monitoring transitions toward adaptive co-management. In so doing, a number of knowledge gaps are addressed. Firstly, conceptual and methodological frameworks are developed for monitoring transitions toward adaptive co-management. Secondly, a conceptual and practical approach to monitoring the processes of collaboration and learning is developed and tested. Thirdly, a conceptual and practical approach to monitoring the governance outcomes of adaptive co-management is developed and tested. Fourthly, a conceptual and practical approach to monitoring the livelihood outcomes of adaptive co-management is developed and tested. Based on the outcomes from these four components of the study, this thesis explores the ways in which transitions toward adaptive co-management might be initiated under the resource poor conditions that characterise South Africa's communal areas. The four case studies explored in the study are described as 'resource poor' in terms of institutional capacity, ecosystem productivity and social vulnerability. From a resilience perspective these case studies can be described as being in the re-organisation phase of the adaptive cycle following multiple disturbances over time, largely due to South Africa's historical 'separate development' policies. Scholars have suggested that it is in this re-organisation phase that innovation and novelty might occur. The lens of social learning is applied to analyse collaborative processes within these contexts. Results indicate that the institutional innovation necessary for transitions toward adaptive co-management relies on careful facilitation by an 'honest broker'. Equally important is finding a balance between maintaining key individuals and knowledge holders within decision making networks, and preventing rigidity and vulnerability within communities of practice. The results point to an over simplification in the rhetoric that currently surrounds the learning outcomes of multi level networks. The governance outcomes of the initiatives are explored through the lenses of adaptive governance, social capital, adaptive capacity and self-organisation. Results indicate that under resource poor conditions creating the conditions that facilitate self-organisation is the major challenge facing transformations toward adaptive governance. Long term access to reliable information and capacity and financial support for adaptive management are key constraining variables. The livelihood outcomes of the initiatives are analysed through the lens of resilience and diversification. Results suggest that flexibility, rather than livelihood diversity, is the key livelihood strategy employed by households in situations were options are limited. Interventions that enhance opportunities for households to specialise in situ by actively dealing with structural constraints, such as access to markets and credit, is vital to encouraging innovation during transitions toward adaptive co-management. Based on the results from monitoring, this study identifies key focus areas that require a great deal more attention if transitions toward adaptive co-management are to be initiated under resource poor conditions.
- Full Text:
- Date Issued: 2009
- Authors: Cundill, Georgina
- Date: 2009
- Subjects: Natural resources -- Co-management -- South Africa Rural poor -- South Africa Rural development -- South Africa Households -- Economic aspects -- South Africa Sustainable development -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4747 , http://hdl.handle.net/10962/d1006961
- Description: Through collaborative monitoring and case study comparison, this thesis explores conceptual and methodological approaches to monitoring transitions toward adaptive co-management. In so doing, a number of knowledge gaps are addressed. Firstly, conceptual and methodological frameworks are developed for monitoring transitions toward adaptive co-management. Secondly, a conceptual and practical approach to monitoring the processes of collaboration and learning is developed and tested. Thirdly, a conceptual and practical approach to monitoring the governance outcomes of adaptive co-management is developed and tested. Fourthly, a conceptual and practical approach to monitoring the livelihood outcomes of adaptive co-management is developed and tested. Based on the outcomes from these four components of the study, this thesis explores the ways in which transitions toward adaptive co-management might be initiated under the resource poor conditions that characterise South Africa's communal areas. The four case studies explored in the study are described as 'resource poor' in terms of institutional capacity, ecosystem productivity and social vulnerability. From a resilience perspective these case studies can be described as being in the re-organisation phase of the adaptive cycle following multiple disturbances over time, largely due to South Africa's historical 'separate development' policies. Scholars have suggested that it is in this re-organisation phase that innovation and novelty might occur. The lens of social learning is applied to analyse collaborative processes within these contexts. Results indicate that the institutional innovation necessary for transitions toward adaptive co-management relies on careful facilitation by an 'honest broker'. Equally important is finding a balance between maintaining key individuals and knowledge holders within decision making networks, and preventing rigidity and vulnerability within communities of practice. The results point to an over simplification in the rhetoric that currently surrounds the learning outcomes of multi level networks. The governance outcomes of the initiatives are explored through the lenses of adaptive governance, social capital, adaptive capacity and self-organisation. Results indicate that under resource poor conditions creating the conditions that facilitate self-organisation is the major challenge facing transformations toward adaptive governance. Long term access to reliable information and capacity and financial support for adaptive management are key constraining variables. The livelihood outcomes of the initiatives are analysed through the lens of resilience and diversification. Results suggest that flexibility, rather than livelihood diversity, is the key livelihood strategy employed by households in situations were options are limited. Interventions that enhance opportunities for households to specialise in situ by actively dealing with structural constraints, such as access to markets and credit, is vital to encouraging innovation during transitions toward adaptive co-management. Based on the results from monitoring, this study identifies key focus areas that require a great deal more attention if transitions toward adaptive co-management are to be initiated under resource poor conditions.
- Full Text:
- Date Issued: 2009
Livestock, rural livelihoods and rural development interventions in the Eastern Cape: case studies of Chris Hani, Alfred Nzo and Amathole district municipalities
- Authors: Phiri, Christopher
- Date: 2009
- Subjects: Rural development -- South Africa -- Eastern Cape Province , Livestock -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , D Soc Sc (Rural Development)
- Identifier: vital:11937 , http://hdl.handle.net/10353/184 , Rural development -- South Africa -- Eastern Cape Province , Livestock -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Description: This study explores how livestock in rural communities were accessed, used as livelihoods portfolios and how off-farm activities and portfolios such as social grants, support from family members and employment assisted the rural poor to build their asset base. Empirical data was collected from 26 villages in the three districts. In particular the study examines firstly, the nature of rural poverty in these villages in the three districts and how households with and without livestock (cattle, sheep, goats, dogs, pigs, cats, ducks, horses and donkeys) used livestock local knowledge to sustain a living. Secondly it explores how the local government and related rural development agencies, intervened in livestock production and the thesis highlights the problematic nature of these interventions, and the implications this has for the form and nature of livestock ownership and use in relation to rural livelihoods. Arising from this, the thesis thirdly explores Ruliv‟s through concrete case studies, the challenges, constraints and implications of a pre-dominant top-down approach to rural development. Contrary to this approach, the study illustrates, through the Rhoxeni case study, the potential effectiveness of a „bottom-up‟ actor oriented approach to rural development. Fourthly, the study explores how local government initiatives intervened in the development of a rural livestock project in Alfred Nzo District Municipality through the Integrated Sustainable Rural Development Programme Goat Project. Here iv the concerns of „commercialisation‟ of livestock production are explored and the thesis points to the implications that the exclusion of social and cultural meanings of livestock have for assumed paths of commercialisation and its associations with development. Fifthly the study explores the potentiality of emerging black commercial farmers who had acquired large areas of agricultural land through local government interventions (Land Redistribution Agricultural Development) but who lacked further support and capacity to transform themselves into commercial farmers. The thesis concludes that their livestock and crop farming activities remained more subsistence and livelihood based, than any transition to expected technical market oriented commercial farming. Overall, the thesis argues that while local government planning for rural development prioritised commercial agriculture as the basis of rural development and the key mechanism of rural poverty alleviation in developmental policies (PGDP, IDP, LED), rural poverty has actually been deepening. In this context, the study argues that the value of livestock to the rural poor lies „outside‟ of its assumed economic value and is more firmly and determinedly located in its social meanings and values, despite these significant levels of material poverty. This has major implications for understanding livelihoods, engaging livestock agency, defining farming and what it means to be a „farmer‟ and engaging with prevalent understandings and practices directed at rural development.
- Full Text:
- Date Issued: 2009
- Authors: Phiri, Christopher
- Date: 2009
- Subjects: Rural development -- South Africa -- Eastern Cape Province , Livestock -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , D Soc Sc (Rural Development)
- Identifier: vital:11937 , http://hdl.handle.net/10353/184 , Rural development -- South Africa -- Eastern Cape Province , Livestock -- South Africa -- Eastern Cape , Rural poor -- South Africa -- Eastern Cape
- Description: This study explores how livestock in rural communities were accessed, used as livelihoods portfolios and how off-farm activities and portfolios such as social grants, support from family members and employment assisted the rural poor to build their asset base. Empirical data was collected from 26 villages in the three districts. In particular the study examines firstly, the nature of rural poverty in these villages in the three districts and how households with and without livestock (cattle, sheep, goats, dogs, pigs, cats, ducks, horses and donkeys) used livestock local knowledge to sustain a living. Secondly it explores how the local government and related rural development agencies, intervened in livestock production and the thesis highlights the problematic nature of these interventions, and the implications this has for the form and nature of livestock ownership and use in relation to rural livelihoods. Arising from this, the thesis thirdly explores Ruliv‟s through concrete case studies, the challenges, constraints and implications of a pre-dominant top-down approach to rural development. Contrary to this approach, the study illustrates, through the Rhoxeni case study, the potential effectiveness of a „bottom-up‟ actor oriented approach to rural development. Fourthly, the study explores how local government initiatives intervened in the development of a rural livestock project in Alfred Nzo District Municipality through the Integrated Sustainable Rural Development Programme Goat Project. Here iv the concerns of „commercialisation‟ of livestock production are explored and the thesis points to the implications that the exclusion of social and cultural meanings of livestock have for assumed paths of commercialisation and its associations with development. Fifthly the study explores the potentiality of emerging black commercial farmers who had acquired large areas of agricultural land through local government interventions (Land Redistribution Agricultural Development) but who lacked further support and capacity to transform themselves into commercial farmers. The thesis concludes that their livestock and crop farming activities remained more subsistence and livelihood based, than any transition to expected technical market oriented commercial farming. Overall, the thesis argues that while local government planning for rural development prioritised commercial agriculture as the basis of rural development and the key mechanism of rural poverty alleviation in developmental policies (PGDP, IDP, LED), rural poverty has actually been deepening. In this context, the study argues that the value of livestock to the rural poor lies „outside‟ of its assumed economic value and is more firmly and determinedly located in its social meanings and values, despite these significant levels of material poverty. This has major implications for understanding livelihoods, engaging livestock agency, defining farming and what it means to be a „farmer‟ and engaging with prevalent understandings and practices directed at rural development.
- Full Text:
- Date Issued: 2009
Mathematical requirements for first-year BCOM students at NMMU
- Authors: Walton, Marguerite
- Date: 2009
- Subjects: Business mathematics -- South Africa , Mathematics -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10502 , http://hdl.handle.net/10948/886 , Business mathematics -- South Africa , Mathematics -- Study and teaching (Higher) -- South Africa
- Description: These studies have focused on identifying the mathematical requirements of first-year BCom students at Nelson Mandela Metropolitan University. The research methodology used in this quantitative study was to make use of interviewing, questionnaire investigation, and document analysis in the form of textbook, test and examination analysis. These methods provided data that fitted into a grounded theory approach. The study concluded by identifying the list of mathematical topics required for the first year of the core subjects in the BCom degree programme. In addition, the study found that learners who study Mathematics in the National Senior Certificate should be able to cope with the mathematical content included in their BCom degree programme, while learners studying Mathematical Literacy would probably need support in some of the areas of mathematics, especially algebra, in order to cope with the mathematical content included in their BCom degree programme. It makes a valuable contribution towards elucidating the mathematical requirements needed to improve the chances of successful BCom degree programme studies at South African universities. It also draws the contours for starting to design an efficient support course for future “at-risk” students who enter higher education studies.
- Full Text:
- Date Issued: 2009
- Authors: Walton, Marguerite
- Date: 2009
- Subjects: Business mathematics -- South Africa , Mathematics -- Study and teaching (Higher) -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10502 , http://hdl.handle.net/10948/886 , Business mathematics -- South Africa , Mathematics -- Study and teaching (Higher) -- South Africa
- Description: These studies have focused on identifying the mathematical requirements of first-year BCom students at Nelson Mandela Metropolitan University. The research methodology used in this quantitative study was to make use of interviewing, questionnaire investigation, and document analysis in the form of textbook, test and examination analysis. These methods provided data that fitted into a grounded theory approach. The study concluded by identifying the list of mathematical topics required for the first year of the core subjects in the BCom degree programme. In addition, the study found that learners who study Mathematics in the National Senior Certificate should be able to cope with the mathematical content included in their BCom degree programme, while learners studying Mathematical Literacy would probably need support in some of the areas of mathematics, especially algebra, in order to cope with the mathematical content included in their BCom degree programme. It makes a valuable contribution towards elucidating the mathematical requirements needed to improve the chances of successful BCom degree programme studies at South African universities. It also draws the contours for starting to design an efficient support course for future “at-risk” students who enter higher education studies.
- Full Text:
- Date Issued: 2009
Milk production and calf performance in Nguni and crossbred cattle raised on communal rangelands of the Eastern Cape province of South Africa
- Authors: Mapekula, Monde
- Date: 2009
- Subjects: Nguni cattle , Communal rangelands -- South Africa -- Eastern Cape , Dairy processing -- South Africa -- Eastern Cape , Milk yield -- South Africa -- Eastern Cape , Amino acids -- South Africa -- Eastern Cape , Fatty acids
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11813 , http://hdl.handle.net/10353/247 , Nguni cattle , Communal rangelands -- South Africa -- Eastern Cape , Dairy processing -- South Africa -- Eastern Cape , Milk yield -- South Africa -- Eastern Cape , Amino acids -- South Africa -- Eastern Cape , Fatty acids
- Description: Information on milk production could be useful in designing strategies that would help to improve milk production in communal farming systems. This study was conducted to determine milk production and calf performance of Nguni and crossbreds under smallholder cattle production conditions. Four trials were conducted in the study. The objective of the first trial was to determine farmer perceptions on milk production and calf rearing in smallholder areas. Data were obtained from 218 smallholder farmers, using a structured questionnaire. Smallholder farmer sector is constituted by small scale commercial farmers and communal farmers. Small-scale commercial farmers in South Africa obtained farms from the government through land claims or they bought the farms. Their farming background is a communal type. Communal farmers are farmers that are sharing the same grazing land and animals are managed according to the experience of the owner. The findings in this study indicated that there were numerous constraints to milk production in smallholder areas. These included lack of technical expertise and poor veterinary support services. The farmers also indicated that calf performance was low. The second trial was conducted to determine if there were differences in calf performance, gastrointestinal parasites and nutritionally-related blood metabolites between Nguni and crossbred calves. Body weights and faecal samples were collected monthly until weaning at six months. The levels of total protein, albumin, globulins, non-esterified fatty acids (NEFA), glucose, cholesterol and minerals were determined monthly. Nguni calves had higher birth weights than crossbreds (P<0.05). Average daily gain and weaning weights of Nguni calves were greater than crossbred calves (P<0.05. Nguni calves had lower total protein at early age after birth (P<0.05). However, at weaning Nguni calves had higher total protein than crossbreds (P<0.05). Nguni calves had higher levels of glucose and NEFA concentrations than crossbred calves (P<0.05). In the third trial, milk utilisation patterns in smallholder areas of the Eastern Cape were assessed. Cattle owners (n = 130) were randomly selected in three different regions to determine milk consumption patterns, milk sales, prices and factors influencing these activities. The information was gathered using milk recording sheets, which were administered in February (early lactation) and June (late lactation) in 2009. Milk consumption per household was similar among the three districts (P>0.05). Milk was utilised as both fresh and sour. Fresh milk was utilised with tea/coffee and porridge. Excess fresh milk was utilised to feed pets (mostly cats and puppies). The puppies were fed on mostly whey, and, at times, on fresh milk. Sour milk was utilised to prepare of umvubo (a mixture of sour milk and scrambled porridge (umphokoqo) or a mixture of sour milk and bread). In some cases, excess milk was given to neighbours as a form of social investment and fame. The quality of milk from Nguni and crossbred cows was compared in the fourth trial. Milk samples were evaluated for quality in early (February), mid (April) and late (June) lactation in 2009. The essential amino acids, non-essential amino acids and fatty acids were determined. Nguni milk had higher amino acids and fatty acids concentration than crossbreds (P<0.05). Nguni milk had higher arginine levels in the early and mid lactation periods compared to crossbred cows (P<0.05). Nguni milk had higher methionine and threonine levels than crossbred cows (P<0.05). Methionine levels in Nguni were 0.15, 0.19 and 0.18 in early, mid and late lactation while crossbred had 0.05, 0.05 and 0.06 (g/100ml), respectively. There were significant interactions between lactation stage and genotype for lysine levels with Nguni milk having higher (P<0.05) lysine levels in the mid and late lactation periods. Nguni cows had higher tyrosine, glycine and proline levels than crossbred cows (P<0.05). In the early lactation, Nguni cows had higher serine levels than crossbred cows (P<0.05). In mid lactation crossbred cows had higher serine levels than Nguni cows (P<0.05). There were significant differences between genotypes on fatty acid composition. Nguni milk had higher C12:0 levels than crossbreds (P<0.05). However, milk from crossbred cows had higher C14:0 levels than that for Nguni cows (P<0.05) and also had higher levels of C16:0 and C18:0 fatty acids compared to Nguni cows. Crossbred milk had higher levels of C18n1n9t in early lactation period than Nguni and decreased as the stage of lactation progressed (P<0.05). In the early lactation, the levels of C18n1nC in Nguni milk were higher (P<0.05) than in late lactation. In the mid and late lactation, crossbred cows milk had higher C18n1nC levels than in early lactation (P<0.05). Lactation stage and genotype affected saturated fatty, monounsaturated fatty acids, cis-fatty acids and omega 3 (n-3) to omega 6 (n-6). In general, Nguni milk had higher mineral composition than crossbred milk (P<0.05). In conclusion, Nguni calves performed better than crossbred calves under communal rangelands. There is a need for crossing Nguni cows with dairy breeds in commercial dairying by smalhoder farmers as a strategy for improving both milk quality and quantity.
- Full Text:
- Date Issued: 2009
- Authors: Mapekula, Monde
- Date: 2009
- Subjects: Nguni cattle , Communal rangelands -- South Africa -- Eastern Cape , Dairy processing -- South Africa -- Eastern Cape , Milk yield -- South Africa -- Eastern Cape , Amino acids -- South Africa -- Eastern Cape , Fatty acids
- Language: English
- Type: Thesis , Doctoral , PhD (Animal Science)
- Identifier: vital:11813 , http://hdl.handle.net/10353/247 , Nguni cattle , Communal rangelands -- South Africa -- Eastern Cape , Dairy processing -- South Africa -- Eastern Cape , Milk yield -- South Africa -- Eastern Cape , Amino acids -- South Africa -- Eastern Cape , Fatty acids
- Description: Information on milk production could be useful in designing strategies that would help to improve milk production in communal farming systems. This study was conducted to determine milk production and calf performance of Nguni and crossbreds under smallholder cattle production conditions. Four trials were conducted in the study. The objective of the first trial was to determine farmer perceptions on milk production and calf rearing in smallholder areas. Data were obtained from 218 smallholder farmers, using a structured questionnaire. Smallholder farmer sector is constituted by small scale commercial farmers and communal farmers. Small-scale commercial farmers in South Africa obtained farms from the government through land claims or they bought the farms. Their farming background is a communal type. Communal farmers are farmers that are sharing the same grazing land and animals are managed according to the experience of the owner. The findings in this study indicated that there were numerous constraints to milk production in smallholder areas. These included lack of technical expertise and poor veterinary support services. The farmers also indicated that calf performance was low. The second trial was conducted to determine if there were differences in calf performance, gastrointestinal parasites and nutritionally-related blood metabolites between Nguni and crossbred calves. Body weights and faecal samples were collected monthly until weaning at six months. The levels of total protein, albumin, globulins, non-esterified fatty acids (NEFA), glucose, cholesterol and minerals were determined monthly. Nguni calves had higher birth weights than crossbreds (P<0.05). Average daily gain and weaning weights of Nguni calves were greater than crossbred calves (P<0.05. Nguni calves had lower total protein at early age after birth (P<0.05). However, at weaning Nguni calves had higher total protein than crossbreds (P<0.05). Nguni calves had higher levels of glucose and NEFA concentrations than crossbred calves (P<0.05). In the third trial, milk utilisation patterns in smallholder areas of the Eastern Cape were assessed. Cattle owners (n = 130) were randomly selected in three different regions to determine milk consumption patterns, milk sales, prices and factors influencing these activities. The information was gathered using milk recording sheets, which were administered in February (early lactation) and June (late lactation) in 2009. Milk consumption per household was similar among the three districts (P>0.05). Milk was utilised as both fresh and sour. Fresh milk was utilised with tea/coffee and porridge. Excess fresh milk was utilised to feed pets (mostly cats and puppies). The puppies were fed on mostly whey, and, at times, on fresh milk. Sour milk was utilised to prepare of umvubo (a mixture of sour milk and scrambled porridge (umphokoqo) or a mixture of sour milk and bread). In some cases, excess milk was given to neighbours as a form of social investment and fame. The quality of milk from Nguni and crossbred cows was compared in the fourth trial. Milk samples were evaluated for quality in early (February), mid (April) and late (June) lactation in 2009. The essential amino acids, non-essential amino acids and fatty acids were determined. Nguni milk had higher amino acids and fatty acids concentration than crossbreds (P<0.05). Nguni milk had higher arginine levels in the early and mid lactation periods compared to crossbred cows (P<0.05). Nguni milk had higher methionine and threonine levels than crossbred cows (P<0.05). Methionine levels in Nguni were 0.15, 0.19 and 0.18 in early, mid and late lactation while crossbred had 0.05, 0.05 and 0.06 (g/100ml), respectively. There were significant interactions between lactation stage and genotype for lysine levels with Nguni milk having higher (P<0.05) lysine levels in the mid and late lactation periods. Nguni cows had higher tyrosine, glycine and proline levels than crossbred cows (P<0.05). In the early lactation, Nguni cows had higher serine levels than crossbred cows (P<0.05). In mid lactation crossbred cows had higher serine levels than Nguni cows (P<0.05). There were significant differences between genotypes on fatty acid composition. Nguni milk had higher C12:0 levels than crossbreds (P<0.05). However, milk from crossbred cows had higher C14:0 levels than that for Nguni cows (P<0.05) and also had higher levels of C16:0 and C18:0 fatty acids compared to Nguni cows. Crossbred milk had higher levels of C18n1n9t in early lactation period than Nguni and decreased as the stage of lactation progressed (P<0.05). In the early lactation, the levels of C18n1nC in Nguni milk were higher (P<0.05) than in late lactation. In the mid and late lactation, crossbred cows milk had higher C18n1nC levels than in early lactation (P<0.05). Lactation stage and genotype affected saturated fatty, monounsaturated fatty acids, cis-fatty acids and omega 3 (n-3) to omega 6 (n-6). In general, Nguni milk had higher mineral composition than crossbred milk (P<0.05). In conclusion, Nguni calves performed better than crossbred calves under communal rangelands. There is a need for crossing Nguni cows with dairy breeds in commercial dairying by smalhoder farmers as a strategy for improving both milk quality and quantity.
- Full Text:
- Date Issued: 2009
Myth, Music & Modernism: the Wagnerian dimension in Virginia Woolf's Mrs Dalloway and the waves and James Joyce’s Finnegans Wake
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
- Authors: McGregor, Jamie Alexander
- Date: 2009
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/77069 , vital:30662
- Description: The study of Wagner's influence on the modernist novel is an established field with clear room for further contributions. Very little of the criticism undertaken to date takes full cognizance of the philosophical content of Wagner's dramas: a revolutionary form of romanticism that calls into question the very nature of the world, its most radical component being Schopenhauer's version of transcendental idealism. The compatibility of this doctrine with Wagner's earlier work, with its already marked privileging of myth over history, enabled his later dramas, consciously influenced by Schopenhauer, to crown a body of work greater than the sum of its parts. In works by Virginia Woolf and James Joyce, the "translation" of Wagnerian ideas into novelistic form demonstrates how they might be applied in "real life". In Mrs Dalloway, the figure of Septimus can be read as partly modelled on Wagner's heroes Siegfried and Tristan, two outstanding examples of the opposing heroic types found throughout his oeuvre, whose contrasting attributes are fused in Septimus's bipolar personality. The Wagnerian pattern also throws light on Septimus's transcendental "relationship" with a woman he does not even know, and on the implied noumenal identity of seemingly isolated individuals. In The Waves, the allusions to both Parsifal and the Ring need to be reconsidered in light of the fact that these works' heroes are all but identical (a fact overlooked in previous criticism); as Wagner's solar hero par excellence, Siegfried is central to the novel's cyclical symbolism. The Waves also revisits the question of identity but in a more cosmic context – the metaphysical unity of everything. In Finnegans Wake, the symbolism of the cosmic cycle is again related to the Ring, as are Wagner's two heroic types to the Shem / Shaun opposition (the Joyce / Woolf parallels here have also been overlooked in criticism to date). All three texts reveal a fascination with the two contrasting faces of a Wagnerian hero who embodies the dual nature of reality, mirroring in himself the eternal rise and fall of world history and, beyond them, the timeless stasis of myth.
- Full Text:
- Date Issued: 2009
New platinum coordination compounds : their synthesis, characterization and anticancer application
- Authors: Oosthuizen, Lukas Marthinus
- Date: 2009
- Subjects: Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10430 , http://hdl.handle.net/10948/d1018795
- Description: The aim of this thesis was to investigate the properties of novel platinum compounds with possible potential as anticancer agents, and to determine how their behaviour could lead to a better understanding of the chemistry involved. The final criteria were improvement of their anticancer behaviour. Since many questions are still unanswered as to the role of sulfur in anticancer action, studies were undertaken to synthesize novel platinum(II) complexes having non-leaving groups consisting of a combination of an aromatic nitrogen and thioetherial sulfur capable of forming a five membered ring upon coordination. The structural unit was 1-methyl-2-methylthioalkyl/aryl. Numerous complexes formed by these ligands each having chloro, bromo, iodo and oxalato leaving groups were then fully characterized. The results obtained by the various synthetic methods were compared and explained in terms of the chemistry involved. The role of the sulfur donor was indicated in both the halo- and oxalato-complexes and proved to be strongly influenced by the nature of the leaving groups. Their differences are reflected in their anticancer behaviour. The study was extended to mononitroplatinum(IV) complexes, in view of the kinetically stable platinum(IV) compounds and advantages related to this. A specific mononitroplatinum(IV) complex which proved to have good anticancer and STAT 3 properties could according to the literature not be synthesized successfully in a good yield and a high degree of purity. The results of extensive studies showed that the main problem centred around the simultaneous reactions in equilibrium during the synthesis. A number of these species formed as a result of side reactions could be identified and their close separation factors indicated chromatographically. The mechanism of these reactions and the unstable intermediate species involved could be rationalized and compared to analogues in the literature. All the complexes studied were characterized by spectral and thermal methods both in solution as well as the solid state. Their anticancer behaviour towards three anticancer cell lines (Hela, MCF 7, Ht 29) were determined and acted as a guide towards possible structural modifications for their improved capability. Three crystal structures of platinum(II) complexes were determined. The extent of the ionization of the platinum(II) complexes as well the redox potentials (Pt(II) / Pt(IV)) of the platinum(IV) complexes were particularly important factors pertaining to their anticancer action.
- Full Text:
- Date Issued: 2009
- Authors: Oosthuizen, Lukas Marthinus
- Date: 2009
- Subjects: Platinum compounds , Antineoplastic agents
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10430 , http://hdl.handle.net/10948/d1018795
- Description: The aim of this thesis was to investigate the properties of novel platinum compounds with possible potential as anticancer agents, and to determine how their behaviour could lead to a better understanding of the chemistry involved. The final criteria were improvement of their anticancer behaviour. Since many questions are still unanswered as to the role of sulfur in anticancer action, studies were undertaken to synthesize novel platinum(II) complexes having non-leaving groups consisting of a combination of an aromatic nitrogen and thioetherial sulfur capable of forming a five membered ring upon coordination. The structural unit was 1-methyl-2-methylthioalkyl/aryl. Numerous complexes formed by these ligands each having chloro, bromo, iodo and oxalato leaving groups were then fully characterized. The results obtained by the various synthetic methods were compared and explained in terms of the chemistry involved. The role of the sulfur donor was indicated in both the halo- and oxalato-complexes and proved to be strongly influenced by the nature of the leaving groups. Their differences are reflected in their anticancer behaviour. The study was extended to mononitroplatinum(IV) complexes, in view of the kinetically stable platinum(IV) compounds and advantages related to this. A specific mononitroplatinum(IV) complex which proved to have good anticancer and STAT 3 properties could according to the literature not be synthesized successfully in a good yield and a high degree of purity. The results of extensive studies showed that the main problem centred around the simultaneous reactions in equilibrium during the synthesis. A number of these species formed as a result of side reactions could be identified and their close separation factors indicated chromatographically. The mechanism of these reactions and the unstable intermediate species involved could be rationalized and compared to analogues in the literature. All the complexes studied were characterized by spectral and thermal methods both in solution as well as the solid state. Their anticancer behaviour towards three anticancer cell lines (Hela, MCF 7, Ht 29) were determined and acted as a guide towards possible structural modifications for their improved capability. Three crystal structures of platinum(II) complexes were determined. The extent of the ionization of the platinum(II) complexes as well the redox potentials (Pt(II) / Pt(IV)) of the platinum(IV) complexes were particularly important factors pertaining to their anticancer action.
- Full Text:
- Date Issued: 2009
On the evaluation of spectral effects on photovoltaic modules performance parameters and hotspots in solar cells
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
- Date Issued: 2009
- Authors: Simon, Michael
- Date: 2009
- Subjects: Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Language: English
- Type: Thesis , Doctoral , PhD (Physics)
- Identifier: vital:11593 , http://hdl.handle.net/10353/257 , Photovoltaic cells , Energy dissipation , Electric power production , Photovoltaic power generation , Solar energy , Spectral energy distribution
- Description: The performance of photovoltaic (PV) modules in terms of their ability to convert incident photon to electrical energy (efficiency) depends mostly on the spectral distribution of incident radiation from the sun. The incident spectrum finally perceived by the module depends strongly on the composition of the medium in which it has traveled. The composition of the earth’s atmosphere, which includes, amongst others, water vapour, gases such as carbon dioxide and oxygen, absorbs or scatters some of the sunlight. The incident solar spectrum is also modified by the diffuse aspect of radiation from the sky which strongly depends on aerosol concentration, cloudiness and local reflection of the earth’s surface. Although it is well known that the changes in outdoor spectrum affect device performance, little work has been conducted to support this theory. This is probably due to lack of spectral data or in certain instances where data is available, little knowledge of interpreting that data. The outdoor spectral data that one obtains in the field does not come clearly for just simple interpretation. Different analytical interpretation procedures have been proposed, all trying to explain and quantify the spectral influence on PV devices. In this study an assessment methodology for evaluating the effects of outdoor spectra on device performance parameters during the course of the day, seasons and or cloudy cover has been developed. The methodology consists of developing a device dependant concept, Weighted Useful Fraction (WUF) using the outdoor measured spectral data. For measuring PV module’s performance parameters, a current-voltage (I-V) tester was developed in order to monitor the performance of six different module technologies. The Gaussian distribution was used to interpret the data. For hot-spot analysis, different techniques were used, which include Infrared thermographic technique for identifying the hot-spots in the solar cells, SEM and EDX techniques. The AES technique was also used in order to identify other elements at hot-spots sites that could not be detected by the EDX technique. iii Results obtained indicate that multicrystalline modules performance is affected by the changes in the outdoor spectrum during summer or winter seasons. The modules prefer a spectrum characterized by WUF = 0.809 during summer season. This spectrum corresponds to AM 2.19 which is different from AM 1.5 used for device ratings. In winter, the mc-Si module’s WUF (0.7125) peaks at 13h00 at a value corresponding to AM 1.83. Although these devices have a wider wavelength range, they respond differently in real outdoor environment. Results for mono – Si module showed that the device performs best at WUF = 0.6457 which corresponds to AM 1.83 during summer season, while it operates optimally under a winter spectrum indicated by WUF of 0.5691 (AM2.58). The seasonal changes resulted in the shift in WUF during day time corresponding to the “preferred” spectrum. This shift indicates that these devices should be rated using AM values that correspond to the WUF values under which the device operates optimally. For poly-Si, it was also observed the WUF values are lower than the other two crystalline-Si counterparts. The pc-Si was observed to prefer a lower AM value indicated by WUF = 0.5813 during winter season while for summer it prefers a spectrum characterized by WUF = 0.5541 at AM 3.36. The performance of the single junction a-Si module degraded by 67 percent after an initial outdoor exposure of 16 kWh/m² while the HIT module did not exhibit the initial degradation regardless of their similarities in material composition. It was established that the WUF before degradation peaks at 15h00 at a value of 0.7130 corresponding to AM 4.50 while the WUF after degradation “prefers” the spectrum (WUF = 0.6578) experienced at 15h30 corresponding to AM value of 5.57. Comparing the before and after degradation scenarios of a-Si:H, it was observed that the device spends less time under the red spectrum which implies that the device “prefers” a full spectrum to operate optimally. The degradation of a-Si:H device revealed that the device spectral response was also shifted by a 7.7 percent after degradation. A higher percentage difference (61.8 percent) for spectral range for the HIT module is observed, but with no effects on device parameters. Seasonal changes (summer/winter) resulted in the outdoor spectrum of CuInSe2 to vary by WUF = 1.5 percent, which resulted in the decrease in Isc. This was ascertained by iv analyzing the percentage change in WUF and evaluating the corresponding change in Isc. The analysis showed that there was a large percentage difference of the module’s Isc as the outdoor spectrum changed during the course of the day. This confirmed that the 17 percent decrease in Isc was due to a WUF of 1.5 percent. In mc-Si solar cells used in this study, it was found that elemental composition across the entire solar cell was not homogenously distributed resulting in high concentration of transition metals which were detected at hot spot areas. The presence of transition metals causes hot-spot formation in crystalline solar cells. Although several transition elements exist at hot-spot regions, the presence of oxygen, carbon, iron and platinum was detected in high concentrations. From this study, it is highly recommended that transition elements and oxygen must be minimized so as to increase the life expectancy of these devices and improve overall systems reliability
- Full Text:
- Date Issued: 2009
Patterns and determinants of species richness in mesic temparate grasslands of South Africa
- Authors: Hoare, David Barry
- Date: 2009
- Subjects: Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10613 , http://hdl.handle.net/10948/1275 , Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Description: The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.
- Full Text:
- Date Issued: 2009
- Authors: Hoare, David Barry
- Date: 2009
- Subjects: Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10613 , http://hdl.handle.net/10948/1275 , Grassland ecology -- South Africa -- Eastern Cape , Plant diversity -- South Africa -- Eastern Cape , Vegetation and climate
- Description: The aim of this study is to gain a predictive understanding of the patterns and determinants of plant biodiversity in temperate, mesic grasslands of South Africa with a primary focus on the geographical area of the Eastern Cape. From a review of the literature on hypotheses explaining diversity (Chapter 2) it was possible to formulate a number of hypotheses that could be tested to explain species richness patterns in Eastern Cape grasslands. This thesis is organised so that each main chapter deals with a specific body of theory concerning the explanation of diversity patterns. A detailed description of the study area is provided (Chapter 3), including environmental variation and a description of major vegetation patterns. A summary is provided of grassland plant community patterns, as determined by phytosociological studies in the study area. A multivariate analysis of environmental variables was undertaken to determine which variables contributed the most towards explaining environmental variation in the study area and to determine whether any variables co-vary, a possible problem for any multivariate analysis in later chapters. Altitude produced one of the strongest gradients in the study area. There were a number of variables that were correlated with altitude, most notably temperature. Rainfall co-varied partially with altitude, but there was also a strong rainfall gradient perpendicular to the altitude gradient. A description of species richness, diversity and evenness patterns at the plot scale within different grassland plant communities of the Eastern Cape is provided in Chapter 4. To determine whether the environment acts differently on different growth forms, the contribution to species richness by different major growth forms is analysed. Furthermore, since the majority of literature attempts to explain diversity in terms of environmental factors, it was necessary to analyse the relationship between species richness and various environmental variables. The results indicate that there is high variation in species richness both within and among grassland communities. Forbs make the most significant contribution to overall species richness per 100 m2, followed by grasses. Variance in richness of all species together is not significantly related to environmental variables in mesic grasslands, but is significantly related to environmental variables in semi-arid grasslands. The result of greatest interest from this chapter is the fact that richness amongst different life-forms in the same place is explained by different environmental factors, indicating that the environmental factors that affect coexistence of species have a different effect on different life-forms. A classification of all the species of the dataset into plant functional types using a multivariate approach based on functional traits was conducted (Chapter 5). The grass species were classified into 16 functional types and the forbs into 14 functional types. The functional type classification provided the opportunity for undertaking analyses to develop an understanding of 8 the contribution by niche differentiation towards promoting species richness (Chapter 6). The results provide evidence of niche differentiation in the grasslands of the study area and also that niche differentiation promotes species richness in the grasslands of the study area. It was found that higher rainfall grasslands are less structured by niche differentiation than semi-arid grasslands. A regional / historical analysis is undertaken (Chapter 7) to investigate the relationship between the regional species pool and local richness, and the relationship between local richness and phytochorological diversity. Regional richness appears to have little effect in promoting local richness in grassland plant communities of the study area except at sites where there is high local richness. This provides an indication that regional richness only promotes local richness in the absence of local limiting factors. Phytochorological diversity promotes local richness, but mostly through diversity amongst species with narrow distribution ranges. Some theories ascertain that seasonal uncertainty may provide opportunities to species that would otherwise be outcompeted and thereby promote local richness. The degree to which seasonal uncertainty and seasonality promote local richness in the Eastern Cape grasslands was therefore investigated (Chapter 8). A weak relationship exists between these variables and local species richness in grassland communities of the study area, indicating that they do not promote niche differentiation to a significant degree in the study area. It is clear that in the grasslands of the Eastern Cape, environmental limiting factors are more important in semi-arid grasslands and species interactions are more important in mesic grasslands for structuring plant communities (Chapter 9, Discussion). Regional processes do not appear to be important in structuring local communities, but the analysis undertaken in this study shows that they may be significant when factors operating at the other two levels are overcome (species interactions and environmental limiting factors.
- Full Text:
- Date Issued: 2009