The use of a rapid incineration field test for determining soil organic carbon in the Southern Cape Region
- Authors: Ackhurst, Albert Arthur
- Date: 2014-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53336 , vital:45135
- Description: Knowledge of soil organic carbon levels is important both for agricultural effectiveness and soil carbon sequestration accounting, especially against the backdrop of increased climate change impacts and pressure on food production landscapes. However, current methods for soil carbon determination are expensive, energy intensive, time consuming and potentially hazardous leading to a call for alternative methods, which should be cheap, fast, simple, accurate, safe and usable where resources and soil analysis laboratories are limited. To this end the student invented a novel rapid incineration field test (RIFT) for determining soil organic carbon and tested its validity in this study. This method incorporates principles found in dry combustion as well as loss-on-ignition and quantifying organic carbon through gravimetric analysis. In order to illustrate effectiveness and accuracy it was necessary to correlate RIFT with a reference method, in this instance dry combustion with a Leco device as well as another commonly used indirect method namely the Walkley-Black wet chemical oxidation method. Samples from eleven soil forms were collected from the Southern Cape region and they were subjected to the three testing methods. It was found that RIFT is indeed as effective and in 72% of the soil forms even more effective than Walkley-Black. Furthermore, it was ascertained whether the accuracy of RIFT can be improved by correcting for clay content. The correlation of RIFT with clay % was not very significant and clay % as a variable was therefore not used in this study to obtain further refinement of RIFT predictions. Another finding was also that RIFT illustrated less variability than both the Leco and Walkley-Black methods. Lastly it was ascertained that the RIFT device and methodology is indeed cost effective, energy efficient, fast and safe in terms of the need to use potentially hazardous chemicals. , Thesis (MA) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2014-12
- Authors: Ackhurst, Albert Arthur
- Date: 2014-12
- Subjects: Port Elizabeth (South Africa) , Eastern Cape (South Africa) , South Africa
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10948/53336 , vital:45135
- Description: Knowledge of soil organic carbon levels is important both for agricultural effectiveness and soil carbon sequestration accounting, especially against the backdrop of increased climate change impacts and pressure on food production landscapes. However, current methods for soil carbon determination are expensive, energy intensive, time consuming and potentially hazardous leading to a call for alternative methods, which should be cheap, fast, simple, accurate, safe and usable where resources and soil analysis laboratories are limited. To this end the student invented a novel rapid incineration field test (RIFT) for determining soil organic carbon and tested its validity in this study. This method incorporates principles found in dry combustion as well as loss-on-ignition and quantifying organic carbon through gravimetric analysis. In order to illustrate effectiveness and accuracy it was necessary to correlate RIFT with a reference method, in this instance dry combustion with a Leco device as well as another commonly used indirect method namely the Walkley-Black wet chemical oxidation method. Samples from eleven soil forms were collected from the Southern Cape region and they were subjected to the three testing methods. It was found that RIFT is indeed as effective and in 72% of the soil forms even more effective than Walkley-Black. Furthermore, it was ascertained whether the accuracy of RIFT can be improved by correcting for clay content. The correlation of RIFT with clay % was not very significant and clay % as a variable was therefore not used in this study to obtain further refinement of RIFT predictions. Another finding was also that RIFT illustrated less variability than both the Leco and Walkley-Black methods. Lastly it was ascertained that the RIFT device and methodology is indeed cost effective, energy efficient, fast and safe in terms of the need to use potentially hazardous chemicals. , Thesis (MA) -- Faculty of Science, School of Natural Resource Management, 2021
- Full Text:
- Date Issued: 2014-12
A comparative assessment of dairy calf feeding management systems at Fernwood Dairy Farm, Alexandria, Eastern Cape
- Phakwago, Potego Steward Kgaditsi
- Authors: Phakwago, Potego Steward Kgaditsi
- Date: 2014
- Subjects: Dairy cattle -- Nutrition -- Requirements , Dairy cattle -- Feeding and feeds , Cattle -- Feed utilization efficiency
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48069 , vital:40468
- Description: The study compared fresh milk as group control to three different milk replacers (Blossom® Easymix, Denkavit® Milk-Bar and Surromel® Calf) and two milk supplements (Byboost Calf® and SupaCalf®) mixed with fresh milk at Fernwood Dairy Farm in Alexandria, Eastern Cape. The objectives of the study were to compare the growth rate of the calves in a trial from day two to 49 at weaning and to calculate average daily gain with the aim of comparison of the cost/weight gain ratio of each liquid feed fed. Sixty Holstein (60) heifer calves were used in a completely randomised design to calculate average daily body weight gains in the six calf groups fed six different milk feeds. Calves were fed four litres liquid feeds every day. Water and solid feeds (Olifantskop® calf starter pellets and lucerne hay) were available. Results comprise of details regarding weather conditions, weight gain results, and body stature measurements, including body weight, wither height, hip height and heart girth. Statistical analysis of the weight gain and body stature measurements was essential to determine the usefulness and reliability of the research data. Results of the statistical calculations indicated that the body weight gain data provided very useful results with statistical significant differences between the six groups (F=5.09; P=0.0008). Body stature measurements are not as reliable. Results are summarised as follows: Liquid feed Cost/kg weight gain Average daily gain • Fresh milk R 34.29 0.50 kg/day • Blossom®Easymix R39.25 0.35 kg/day • Denkavit® Milk-Bar R22.57 0.42 kg/day • Surromel® Calf R23.48 0.39 kg/day • Fresh milk + Byboost Calf® R37.46 0.47 kg/day • Fresh milk +SupaCalf® R29.76 0.62 kg/day Comparison of the cost/weight gain ratio of milk replacers and fresh milk draws the following conclusions: The cost of feeding a calf was significantly lower when milk replacers Denkavit® and Surromel® were used; however this yielded a lower average daily gain when compared with that of fresh milk. Denkavit® milk replacer had a lower cost than fresh milk in terms of the average daily gain. The cost of the Denkavit was the lowest of all the products (R22.56/kg) and was in the fourth position in weight gain (0.42kg/day). Surromel® lay in the fifth place for both cost (R23.48/kg) and weight gain (0.39 kg/day). Blossom® Easymix milk replacer had a higher cost than fresh milk. Blossom was the most costly of all the feeds (R39.25/kg) but had the lowest average daily gain (0.35 kg/day). Comparison of fresh milk plus additives to fresh milk alone: The use of SupaCalf® additive to fresh milk resulted in the highest average daily gain of 0.62 kg/day at a cost of R29.76/kg which was more cost effective than the control fresh milk group (0.50 kg/day, R34.29/kg), When using Byboost® additive the average daily gain of 0.47 kg/day at a cost of R37.46, less cost effective than fresh milk (0.50 kg/day, R34.29). Statistical analysis of body stature measurements yielded one significant result(F=3.20; p=0.0140) confirming that use of SupaCalf® additive resulted in the biggest heart girth increase at 16.90 cm and the smallest being Blossom® Easymix at 11.88 cm. Figure for the control fresh milk group was 12.86 cm. Dairy calves all over the world are fed different feeds depending on the farm owner or manager’s preference and budget. For those who have been in the industry for a while as well as the newcomers, this study can help when weighing options and deciding on which feeds to use.
- Full Text:
- Date Issued: 2014
- Authors: Phakwago, Potego Steward Kgaditsi
- Date: 2014
- Subjects: Dairy cattle -- Nutrition -- Requirements , Dairy cattle -- Feeding and feeds , Cattle -- Feed utilization efficiency
- Language: English
- Type: Thesis , Masters , MTech
- Identifier: http://hdl.handle.net/10948/48069 , vital:40468
- Description: The study compared fresh milk as group control to three different milk replacers (Blossom® Easymix, Denkavit® Milk-Bar and Surromel® Calf) and two milk supplements (Byboost Calf® and SupaCalf®) mixed with fresh milk at Fernwood Dairy Farm in Alexandria, Eastern Cape. The objectives of the study were to compare the growth rate of the calves in a trial from day two to 49 at weaning and to calculate average daily gain with the aim of comparison of the cost/weight gain ratio of each liquid feed fed. Sixty Holstein (60) heifer calves were used in a completely randomised design to calculate average daily body weight gains in the six calf groups fed six different milk feeds. Calves were fed four litres liquid feeds every day. Water and solid feeds (Olifantskop® calf starter pellets and lucerne hay) were available. Results comprise of details regarding weather conditions, weight gain results, and body stature measurements, including body weight, wither height, hip height and heart girth. Statistical analysis of the weight gain and body stature measurements was essential to determine the usefulness and reliability of the research data. Results of the statistical calculations indicated that the body weight gain data provided very useful results with statistical significant differences between the six groups (F=5.09; P=0.0008). Body stature measurements are not as reliable. Results are summarised as follows: Liquid feed Cost/kg weight gain Average daily gain • Fresh milk R 34.29 0.50 kg/day • Blossom®Easymix R39.25 0.35 kg/day • Denkavit® Milk-Bar R22.57 0.42 kg/day • Surromel® Calf R23.48 0.39 kg/day • Fresh milk + Byboost Calf® R37.46 0.47 kg/day • Fresh milk +SupaCalf® R29.76 0.62 kg/day Comparison of the cost/weight gain ratio of milk replacers and fresh milk draws the following conclusions: The cost of feeding a calf was significantly lower when milk replacers Denkavit® and Surromel® were used; however this yielded a lower average daily gain when compared with that of fresh milk. Denkavit® milk replacer had a lower cost than fresh milk in terms of the average daily gain. The cost of the Denkavit was the lowest of all the products (R22.56/kg) and was in the fourth position in weight gain (0.42kg/day). Surromel® lay in the fifth place for both cost (R23.48/kg) and weight gain (0.39 kg/day). Blossom® Easymix milk replacer had a higher cost than fresh milk. Blossom was the most costly of all the feeds (R39.25/kg) but had the lowest average daily gain (0.35 kg/day). Comparison of fresh milk plus additives to fresh milk alone: The use of SupaCalf® additive to fresh milk resulted in the highest average daily gain of 0.62 kg/day at a cost of R29.76/kg which was more cost effective than the control fresh milk group (0.50 kg/day, R34.29/kg), When using Byboost® additive the average daily gain of 0.47 kg/day at a cost of R37.46, less cost effective than fresh milk (0.50 kg/day, R34.29). Statistical analysis of body stature measurements yielded one significant result(F=3.20; p=0.0140) confirming that use of SupaCalf® additive resulted in the biggest heart girth increase at 16.90 cm and the smallest being Blossom® Easymix at 11.88 cm. Figure for the control fresh milk group was 12.86 cm. Dairy calves all over the world are fed different feeds depending on the farm owner or manager’s preference and budget. For those who have been in the industry for a while as well as the newcomers, this study can help when weighing options and deciding on which feeds to use.
- Full Text:
- Date Issued: 2014
A context-aware model to improve usability of information presented on mobile devices
- Authors: Ntawanga, Felix Fred
- Date: 2014
- Subjects: Context-aware computing , Online information services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10495 , http://hdl.handle.net/10948/d1020768
- Description: Online information access on mobile devices is increasing as a result of the growth in the use of Internet-enabled handheld (or pocket-size) devices. The combined influence of recent enabling technologies such as Web 2.0, mobile app stores and improved wireless networks have driven the increase in online applications that allow users to access various types of information on mobile devices regardless of time and location. Examples of such applications (usually shortened to app) include: social media, such as FacebookTM App and TwitterTM App, banking applications such as (Standard Bank South Africa)TM Mobile Banking App and First National Bank (FNB) BankingTM App, and news application such as news 24TM App and BBCTM News App. Online businesses involved in buying, selling and business transaction processing activities via the Internet have exploited the opportunity to extend electronic commerce (e-commerce) initiatives into mobile commerce (m-commerce). Online businesses that interact with end user customers implement business to consumer (B2C) m-commerce applications that enable customers to access and browse product catalogue information on mobile devices, anytime, anywhere. Customers accessing electronic product catalogue information on a mobile device face a number of challenges such as a long list of products presented on a small screen and a longer information download time. These challenges mainly originate from the limiting and dynamic nature of the mobile apps operating environment, for example, dynamic location, bandwidth fluctuations and, diverse and limited device features, collectively referred to as context. The goal of this research was to design and implement a context-aware model that can be incorporated into an m-commerce application in order to improve the presentation of product catalogue information on m-commerce storefronts. The motivation for selecting product catalogue is prompted by literature which indicates that improved presentation of information in m-commerce (and e-commerce) applications has a positive impact on usability of the websites. Usable m-commerce (and e-commerce) websites improve efficiency in consumer behaviour that impacts sales, profits and business growth. The context-aware model aimed at collecting context information within the user environment and utilising it to determine optimal retrieval and presentation of product catalogue in m-commerce. An integrated logical context sensor and Mathematical algorithms were implemented in the context-aware model. The integrated logical context sensor was responsible for the collection of different types of predetermined context information such as device specification or capabilities, connection bandwidth, location and time of the day as well as the user profile. The algorithms transformed the collected context information into usable formats and enabled optimal retrieval and presentation of product catalogue data on a specific mobile device. Open-source implementation tools were utilised to implement components of the model including: HTML5, PhP, JavaScript and MySQL database. The context-aware model was incorporated into an existing m-commerce application. Two user evaluation studies were conducted during the course of the research. The first evaluation was to evaluate the accuracy of information collected by the context sensor component of the model. This survey was conducted with a sample of 30 users from different countries across the world. In-between the context sensor and main evaluation surveys, a pilot study was conducted with a sample of 19 users with great experience in mobile application development and use from SAP Next Business and Technology, Africa. Finally an overall user evaluation study was conducted with a sample of 30 users from a remote area called Kgautswane in Limpopo Province, South Africa. The results obtained indicate that the context-aware model was able to determine accurate context information in real-time and effectively determine how much product information should be retrieved and how the information should be presented on a mobile device interface. Two main contributions emerged from the research, first the research contributed to the field of mobile Human Computer Interaction. During the research, techniques of evaluating and improving usability of mobile applications were demonstrated. Secondly, the research made a significant contribution to the upcoming field of context-aware computing. The research brought clarity with regard to context-aware computing which is lacking in existing, current research despite the field’s proven impact of improving usability of applications. Researchers can utilise contributions made in this research to develop further techniques and usable context-aware solutions.
- Full Text:
- Date Issued: 2014
- Authors: Ntawanga, Felix Fred
- Date: 2014
- Subjects: Context-aware computing , Online information services
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10495 , http://hdl.handle.net/10948/d1020768
- Description: Online information access on mobile devices is increasing as a result of the growth in the use of Internet-enabled handheld (or pocket-size) devices. The combined influence of recent enabling technologies such as Web 2.0, mobile app stores and improved wireless networks have driven the increase in online applications that allow users to access various types of information on mobile devices regardless of time and location. Examples of such applications (usually shortened to app) include: social media, such as FacebookTM App and TwitterTM App, banking applications such as (Standard Bank South Africa)TM Mobile Banking App and First National Bank (FNB) BankingTM App, and news application such as news 24TM App and BBCTM News App. Online businesses involved in buying, selling and business transaction processing activities via the Internet have exploited the opportunity to extend electronic commerce (e-commerce) initiatives into mobile commerce (m-commerce). Online businesses that interact with end user customers implement business to consumer (B2C) m-commerce applications that enable customers to access and browse product catalogue information on mobile devices, anytime, anywhere. Customers accessing electronic product catalogue information on a mobile device face a number of challenges such as a long list of products presented on a small screen and a longer information download time. These challenges mainly originate from the limiting and dynamic nature of the mobile apps operating environment, for example, dynamic location, bandwidth fluctuations and, diverse and limited device features, collectively referred to as context. The goal of this research was to design and implement a context-aware model that can be incorporated into an m-commerce application in order to improve the presentation of product catalogue information on m-commerce storefronts. The motivation for selecting product catalogue is prompted by literature which indicates that improved presentation of information in m-commerce (and e-commerce) applications has a positive impact on usability of the websites. Usable m-commerce (and e-commerce) websites improve efficiency in consumer behaviour that impacts sales, profits and business growth. The context-aware model aimed at collecting context information within the user environment and utilising it to determine optimal retrieval and presentation of product catalogue in m-commerce. An integrated logical context sensor and Mathematical algorithms were implemented in the context-aware model. The integrated logical context sensor was responsible for the collection of different types of predetermined context information such as device specification or capabilities, connection bandwidth, location and time of the day as well as the user profile. The algorithms transformed the collected context information into usable formats and enabled optimal retrieval and presentation of product catalogue data on a specific mobile device. Open-source implementation tools were utilised to implement components of the model including: HTML5, PhP, JavaScript and MySQL database. The context-aware model was incorporated into an existing m-commerce application. Two user evaluation studies were conducted during the course of the research. The first evaluation was to evaluate the accuracy of information collected by the context sensor component of the model. This survey was conducted with a sample of 30 users from different countries across the world. In-between the context sensor and main evaluation surveys, a pilot study was conducted with a sample of 19 users with great experience in mobile application development and use from SAP Next Business and Technology, Africa. Finally an overall user evaluation study was conducted with a sample of 30 users from a remote area called Kgautswane in Limpopo Province, South Africa. The results obtained indicate that the context-aware model was able to determine accurate context information in real-time and effectively determine how much product information should be retrieved and how the information should be presented on a mobile device interface. Two main contributions emerged from the research, first the research contributed to the field of mobile Human Computer Interaction. During the research, techniques of evaluating and improving usability of mobile applications were demonstrated. Secondly, the research made a significant contribution to the upcoming field of context-aware computing. The research brought clarity with regard to context-aware computing which is lacking in existing, current research despite the field’s proven impact of improving usability of applications. Researchers can utilise contributions made in this research to develop further techniques and usable context-aware solutions.
- Full Text:
- Date Issued: 2014
A framework for the management of environmental information in Higher Education Institutions
- Authors: Jonamu, Blessing Tapiwa
- Date: 2014
- Subjects: Sustainability , Universities and colleges , Environmental management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10492 , http://hdl.handle.net/10948/d1020620
- Description: Higher Education Institutions (HEIs) are not immune to the global environment problems. An increasing awareness of the environmental responsibilities of HEIs has led researchers to investigate the role of environmental information and Environmental Management Information Systems (EMISs) in HEIs. EMISs play a major role in environmental management and environmental decision making in HEIs. Internationally, an increasing number of HEIs are embracing the concept of ‘sustainable HEIs’ by undertaking green campus initiatives. HEIs often use diverse information systems, some of which are manual systems, proven to be inefficient and this gives rise to redundant and inconsistent databases which result in non-compliance with regulations, confusion and lack of co-ordinated effort. There is therefore need for an integrated, comprehensive software system and framework which can assist with the efficient management of environmental information at South African HEIs. This study fills a gap in the field of environmental sustainability at HEIs as the evaluation of existing sustainability programs has shown common weakness such as: Failure to effectively set baselines, flaws in data acquisition and management and missing documentation. The aim of this study is to propose a framework for Environmental Information Management (EIM) in HEIs. The framework includes guidelines related to the components of the framework which can also be used to perform a gap analysis to facilitate the improved design of effective and efficient EIM processes and data stores. The Design Science Research (DSR) methodology is the research methodology used in the development of the two artifacts of this study namely: The EIM framework for HEIs and an EMIS prototype to serve as proof of concept. Problem identification and motivation was the first activity of the DSR which was done through a rigorous literature review and an investigation and evaluation of extant systems. This resulted in the design of an initial EIM framework for HEIs. Nelson Mandela Metropolitan University (NMMU) was the HEI used as the case study. The EIM framework was applied at NMMU and this enabled the researcher to understand the current As-Is EIM processes at NMMU and this resulted in clear objectives of a solution. The EMIS prototype (data warehouse) was then designed and implemented based on the theoretical framework. Three sets of evaluations were done to determine the acceptance of the EIM framework for HEIs and the performance of the EMIS prototype. The EIM framework was generally positively accepted and minor suggestions were made. An updated version of the EIM framework was proposed and evaluated. The experimental evaluation results showed that the EMIS prototype was efficient and effective. The contribution of this study is an EIM framework for HEIs and an implementation of an EMIS (EnviroDW) at NMMU that could be utilised by other HEIs.
- Full Text:
- Date Issued: 2014
- Authors: Jonamu, Blessing Tapiwa
- Date: 2014
- Subjects: Sustainability , Universities and colleges , Environmental management
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10492 , http://hdl.handle.net/10948/d1020620
- Description: Higher Education Institutions (HEIs) are not immune to the global environment problems. An increasing awareness of the environmental responsibilities of HEIs has led researchers to investigate the role of environmental information and Environmental Management Information Systems (EMISs) in HEIs. EMISs play a major role in environmental management and environmental decision making in HEIs. Internationally, an increasing number of HEIs are embracing the concept of ‘sustainable HEIs’ by undertaking green campus initiatives. HEIs often use diverse information systems, some of which are manual systems, proven to be inefficient and this gives rise to redundant and inconsistent databases which result in non-compliance with regulations, confusion and lack of co-ordinated effort. There is therefore need for an integrated, comprehensive software system and framework which can assist with the efficient management of environmental information at South African HEIs. This study fills a gap in the field of environmental sustainability at HEIs as the evaluation of existing sustainability programs has shown common weakness such as: Failure to effectively set baselines, flaws in data acquisition and management and missing documentation. The aim of this study is to propose a framework for Environmental Information Management (EIM) in HEIs. The framework includes guidelines related to the components of the framework which can also be used to perform a gap analysis to facilitate the improved design of effective and efficient EIM processes and data stores. The Design Science Research (DSR) methodology is the research methodology used in the development of the two artifacts of this study namely: The EIM framework for HEIs and an EMIS prototype to serve as proof of concept. Problem identification and motivation was the first activity of the DSR which was done through a rigorous literature review and an investigation and evaluation of extant systems. This resulted in the design of an initial EIM framework for HEIs. Nelson Mandela Metropolitan University (NMMU) was the HEI used as the case study. The EIM framework was applied at NMMU and this enabled the researcher to understand the current As-Is EIM processes at NMMU and this resulted in clear objectives of a solution. The EMIS prototype (data warehouse) was then designed and implemented based on the theoretical framework. Three sets of evaluations were done to determine the acceptance of the EIM framework for HEIs and the performance of the EMIS prototype. The EIM framework was generally positively accepted and minor suggestions were made. An updated version of the EIM framework was proposed and evaluated. The experimental evaluation results showed that the EMIS prototype was efficient and effective. The contribution of this study is an EIM framework for HEIs and an implementation of an EMIS (EnviroDW) at NMMU that could be utilised by other HEIs.
- Full Text:
- Date Issued: 2014
A hybrid model for managing personal health records in South Africa
- Authors: Kyazze, Michael
- Date: 2014
- Subjects: Cloud computing -- South Africa , Information storage and retrieval systems -- Medical care -- South Africa , Medical records -- Management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3145 , vital:20403
- Description: Doctors can experience difficulty in accessing medical information of new patients. One reason for this is that the management of medical records is mostly institution-centred. The lack of access to medical information may negatively affect patients in several ways. These include new medical tests that may need to be carried out at a cost to the patient and doctors prescribing drugs to which the patient is allergic. This research investigates how patients can play an active role in sharing their personal health records (PHRs) with doctors located in geographically separate areas. In order to achieve the goal of this research, existing literature concerning medical health records and standards was reviewed. A literature review of techniques that can be used to ensure privacy of health information was also undertaken. Interview studies were carried out with three medical practices in Port Elizabeth with the aim of contextualising the findings from the literature study. The Design Science Research methodology was used for this research. A Hybrid Model for Managing Personal Health Records in South Africa is proposed. This model allows patients to view their PHRs on their mobile phones and medical practitioners to manage the patients’ PHRs using a web-based application. The patients’ PHR information is stored both on a cloud server and on mobile devices hence the hybrid nature. Two prototypes were developed as a proof of concept; a mobile application for the patients and a web-based application for the medical practitioners. A field study was carried out with the NMMU health services department and 12 participants over a period of two weeks. The results of the field study were highly positive. The successful evaluation of the prototypes provides empirical evidence that the proposed model brings us closer to the realisation of ubiquitous access to PHRS in South Africa.
- Full Text:
- Date Issued: 2014
- Authors: Kyazze, Michael
- Date: 2014
- Subjects: Cloud computing -- South Africa , Information storage and retrieval systems -- Medical care -- South Africa , Medical records -- Management -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3145 , vital:20403
- Description: Doctors can experience difficulty in accessing medical information of new patients. One reason for this is that the management of medical records is mostly institution-centred. The lack of access to medical information may negatively affect patients in several ways. These include new medical tests that may need to be carried out at a cost to the patient and doctors prescribing drugs to which the patient is allergic. This research investigates how patients can play an active role in sharing their personal health records (PHRs) with doctors located in geographically separate areas. In order to achieve the goal of this research, existing literature concerning medical health records and standards was reviewed. A literature review of techniques that can be used to ensure privacy of health information was also undertaken. Interview studies were carried out with three medical practices in Port Elizabeth with the aim of contextualising the findings from the literature study. The Design Science Research methodology was used for this research. A Hybrid Model for Managing Personal Health Records in South Africa is proposed. This model allows patients to view their PHRs on their mobile phones and medical practitioners to manage the patients’ PHRs using a web-based application. The patients’ PHR information is stored both on a cloud server and on mobile devices hence the hybrid nature. Two prototypes were developed as a proof of concept; a mobile application for the patients and a web-based application for the medical practitioners. A field study was carried out with the NMMU health services department and 12 participants over a period of two weeks. The results of the field study were highly positive. The successful evaluation of the prototypes provides empirical evidence that the proposed model brings us closer to the realisation of ubiquitous access to PHRS in South Africa.
- Full Text:
- Date Issued: 2014
A hybridisation technique for game playing using the upper confidence for trees algorithm with artificial neural networks
- Authors: Burger, Clayton
- Date: 2014
- Subjects: Neural networks (Computer science) , Computer algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3957 , vital:20495
- Description: In the domain of strategic game playing, the use of statistical techniques such as the Upper Confidence for Trees (UCT) algorithm, has become the norm as they offer many benefits over classical algorithms. These benefits include requiring no game-specific strategic knowledge and time-scalable performance. UCT does not incorporate any strategic information specific to the game considered, but instead uses repeated sampling to effectively brute-force search through the game tree or search space. The lack of game-specific knowledge in UCT is thus both a benefit but also a strategic disadvantage. Pattern recognition techniques, specifically Neural Networks (NN), were identified as a means of addressing the lack of game-specific knowledge in UCT. Through a novel hybridisation technique which combines UCT and trained NNs for pruning, the UCTNN algorithm was derived. The NN component of UCT-NN was trained using a UCT self-play scheme to generate game-specific knowledge without the need to construct and manage game databases for training purposes. The UCT-NN algorithm is outlined for pruning in the game of Go-Moku as a candidate case-study for this research. The UCT-NN algorithm contained three major parameters which emerged from the UCT algorithm, the use of NNs and the pruning schemes considered. Suitable methods for finding candidate values for these three parameters were outlined and applied to the game of Go-Moku on a 5 by 5 board. An empirical investigation of the playing performance of UCT-NN was conducted in comparison to UCT through three benchmarks. The benchmarks comprise a common randomly moving opponent, a common UCTmax player which is given a large amount of playing time, and a pair-wise tournament between UCT-NN and UCT. The results of the performance evaluation for 5 by 5 Go-Moku were promising, which prompted an evaluation of a larger 9 by 9 Go-Moku board. The results of both evaluations indicate that the time allocated to the UCT-NN algorithm directly affects its performance when compared to UCT. The UCT-NN algorithm generally performs better than UCT in games with very limited time-constraints in all benchmarks considered except when playing against a randomly moving player in 9 by 9 Go-Moku. In real-time and near-real-time Go-Moku games, UCT-NN provides statistically significant improvements compared to UCT. The findings of this research contribute to the realisation of applying game-specific knowledge to the UCT algorithm.
- Full Text:
- Date Issued: 2014
- Authors: Burger, Clayton
- Date: 2014
- Subjects: Neural networks (Computer science) , Computer algorithms
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/3957 , vital:20495
- Description: In the domain of strategic game playing, the use of statistical techniques such as the Upper Confidence for Trees (UCT) algorithm, has become the norm as they offer many benefits over classical algorithms. These benefits include requiring no game-specific strategic knowledge and time-scalable performance. UCT does not incorporate any strategic information specific to the game considered, but instead uses repeated sampling to effectively brute-force search through the game tree or search space. The lack of game-specific knowledge in UCT is thus both a benefit but also a strategic disadvantage. Pattern recognition techniques, specifically Neural Networks (NN), were identified as a means of addressing the lack of game-specific knowledge in UCT. Through a novel hybridisation technique which combines UCT and trained NNs for pruning, the UCTNN algorithm was derived. The NN component of UCT-NN was trained using a UCT self-play scheme to generate game-specific knowledge without the need to construct and manage game databases for training purposes. The UCT-NN algorithm is outlined for pruning in the game of Go-Moku as a candidate case-study for this research. The UCT-NN algorithm contained three major parameters which emerged from the UCT algorithm, the use of NNs and the pruning schemes considered. Suitable methods for finding candidate values for these three parameters were outlined and applied to the game of Go-Moku on a 5 by 5 board. An empirical investigation of the playing performance of UCT-NN was conducted in comparison to UCT through three benchmarks. The benchmarks comprise a common randomly moving opponent, a common UCTmax player which is given a large amount of playing time, and a pair-wise tournament between UCT-NN and UCT. The results of the performance evaluation for 5 by 5 Go-Moku were promising, which prompted an evaluation of a larger 9 by 9 Go-Moku board. The results of both evaluations indicate that the time allocated to the UCT-NN algorithm directly affects its performance when compared to UCT. The UCT-NN algorithm generally performs better than UCT in games with very limited time-constraints in all benchmarks considered except when playing against a randomly moving player in 9 by 9 Go-Moku. In real-time and near-real-time Go-Moku games, UCT-NN provides statistically significant improvements compared to UCT. The findings of this research contribute to the realisation of applying game-specific knowledge to the UCT algorithm.
- Full Text:
- Date Issued: 2014
A method for the evaluation of similarity measures on graphs and network-structured data
- Authors: Naude, Kevin Alexander
- Date: 2014
- Subjects: Graph theory , Network analysis (Planning)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10494
- Description: Measures of similarity play a subtle but important role in a large number of disciplines. For example, a researcher in bioinformatics may devise a new computed measure of similarity between biological structures, and use its scores to infer bio-logical association. Other academics may use related approaches in structured text search, or for object recognition in computer vision. These are diverse and practical applications of similarity. A critical question is this: to what extent can a given similarity measure be trusted? This is a difficult problem, at the heart of which lies the broader issue: what exactly constitutes good similarity judgement? This research presents the view that similarity measures have properties of judgement that are intrinsic to their formulation, and that such properties are measurable. The problem of comparing similarity measures is one of identifying ground-truths for similarity. The approach taken in this work is to examine the relative ordering of graph pairs, when compared with respect to a common reference graph. Ground- truth outcomes are obtained from a novel theory: the theory of irreducible change in graphs. This theory supports stronger claims than those made for edit distances. Whereas edit distances are sensitive to a configuration of costs, irreducible change under the new theory is independent of such parameters. Ground-truth data is obtained by isolating test cases for which a common outcome is assured for all possible least measures of change that can be formulated within a chosen change descriptor space. By isolating these specific cases, and excluding others, the research introduces a framework for evaluating similarity measures on mathematically defensible grounds. The evaluation method is demonstrated in a series of case studies which evaluate the similarity performance of known graph similarity measures. The findings of these experiments provide the first general characterisation of common similarity measures over a wide range of graph properties. The similarity computed from the maximum common induced subgraph (Dice-MCIS) is shown to provide good general similarity judgement. However, it is shown that Blondel's similarity measure can exceed the judgement sensitivity of Dice-MCIS, provided the graphs have both sufficient attribute label diversity, and edge density. The final contribution is the introduction of a new similarity measure for graphs, which is shown to have statistically greater judgement sensitivity than all other measures examined. All of these findings are made possible through the theory of irreducible change in graphs. The research provides the first mathematical basis for reasoning about the quality of similarity judgments. This enables researchers to analyse similarity measures directly, making similarity measures first class objects of scientific inquiry.
- Full Text:
- Date Issued: 2014
- Authors: Naude, Kevin Alexander
- Date: 2014
- Subjects: Graph theory , Network analysis (Planning)
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: vital:10494
- Description: Measures of similarity play a subtle but important role in a large number of disciplines. For example, a researcher in bioinformatics may devise a new computed measure of similarity between biological structures, and use its scores to infer bio-logical association. Other academics may use related approaches in structured text search, or for object recognition in computer vision. These are diverse and practical applications of similarity. A critical question is this: to what extent can a given similarity measure be trusted? This is a difficult problem, at the heart of which lies the broader issue: what exactly constitutes good similarity judgement? This research presents the view that similarity measures have properties of judgement that are intrinsic to their formulation, and that such properties are measurable. The problem of comparing similarity measures is one of identifying ground-truths for similarity. The approach taken in this work is to examine the relative ordering of graph pairs, when compared with respect to a common reference graph. Ground- truth outcomes are obtained from a novel theory: the theory of irreducible change in graphs. This theory supports stronger claims than those made for edit distances. Whereas edit distances are sensitive to a configuration of costs, irreducible change under the new theory is independent of such parameters. Ground-truth data is obtained by isolating test cases for which a common outcome is assured for all possible least measures of change that can be formulated within a chosen change descriptor space. By isolating these specific cases, and excluding others, the research introduces a framework for evaluating similarity measures on mathematically defensible grounds. The evaluation method is demonstrated in a series of case studies which evaluate the similarity performance of known graph similarity measures. The findings of these experiments provide the first general characterisation of common similarity measures over a wide range of graph properties. The similarity computed from the maximum common induced subgraph (Dice-MCIS) is shown to provide good general similarity judgement. However, it is shown that Blondel's similarity measure can exceed the judgement sensitivity of Dice-MCIS, provided the graphs have both sufficient attribute label diversity, and edge density. The final contribution is the introduction of a new similarity measure for graphs, which is shown to have statistically greater judgement sensitivity than all other measures examined. All of these findings are made possible through the theory of irreducible change in graphs. The research provides the first mathematical basis for reasoning about the quality of similarity judgments. This enables researchers to analyse similarity measures directly, making similarity measures first class objects of scientific inquiry.
- Full Text:
- Date Issued: 2014
A study of the reintegration of female former child soldiers in Gulu District, northern Uganda
- Authors: Bertelsen, Anna
- Date: 2014
- Subjects: Women soldiers -- Uganda -- Gulu District , Child soldiers -- Uganda -- Gulu District , Patriarchy -- Uganda -- Gulu District
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:8324 , http://hdl.handle.net/10948/d1020192
- Description: This research explores the perceptions and experiences of female former child soldiers in regard to their reintegration within the community of Gulu District, northern Uganda. In many societies women are generally excluded due to prevailing patriarchal hegemonies, with northern Uganda being no exception. Moreover, former child soldiers are commonly marginalized and discriminated against because members of communities commonly believe that they should be punished for the perceived atrocities that they allegedly committed during times of conflict, rather than be reintegrated into society. In this regard female former child soldiers can be identified as a particularly vulnerable and marginalized group. Therefore, it can be suggested that although the distinction between traditional gender roles has been eroded during times of armed conflict, there is still widespread evidence that women are largely overlooked and disregarded in the process of peace building. In order to explore the perceptions and experiences of former female child soldiers, a qualitative case study method was utilized based on in-depth face to face interviews with women from Gulu District, northern Uganda. The findings of this study indicate that, even though these women went through considerable hardships, all of them displayed a strong sense of resilience. Many of them had taken on the role as active change agents in their own lives and provided an array of suggestions on how their situation could be improved. The major themes constructed from the study include: challenges facing returnees; facilitating factors for returnees and suggestions on improved reintegration. Based on these findings a number of recommendations emerged. The recommendations are presented in order to assist organizations and other stakeholders involved in reintegration of child soldiers in northern Uganda and elsewhere in the world. Apart from providing information to the existing body of research, future areas of proposed research are also outlined.
- Full Text:
- Date Issued: 2014
- Authors: Bertelsen, Anna
- Date: 2014
- Subjects: Women soldiers -- Uganda -- Gulu District , Child soldiers -- Uganda -- Gulu District , Patriarchy -- Uganda -- Gulu District
- Language: English
- Type: Thesis , Masters , MPhil
- Identifier: vital:8324 , http://hdl.handle.net/10948/d1020192
- Description: This research explores the perceptions and experiences of female former child soldiers in regard to their reintegration within the community of Gulu District, northern Uganda. In many societies women are generally excluded due to prevailing patriarchal hegemonies, with northern Uganda being no exception. Moreover, former child soldiers are commonly marginalized and discriminated against because members of communities commonly believe that they should be punished for the perceived atrocities that they allegedly committed during times of conflict, rather than be reintegrated into society. In this regard female former child soldiers can be identified as a particularly vulnerable and marginalized group. Therefore, it can be suggested that although the distinction between traditional gender roles has been eroded during times of armed conflict, there is still widespread evidence that women are largely overlooked and disregarded in the process of peace building. In order to explore the perceptions and experiences of former female child soldiers, a qualitative case study method was utilized based on in-depth face to face interviews with women from Gulu District, northern Uganda. The findings of this study indicate that, even though these women went through considerable hardships, all of them displayed a strong sense of resilience. Many of them had taken on the role as active change agents in their own lives and provided an array of suggestions on how their situation could be improved. The major themes constructed from the study include: challenges facing returnees; facilitating factors for returnees and suggestions on improved reintegration. Based on these findings a number of recommendations emerged. The recommendations are presented in order to assist organizations and other stakeholders involved in reintegration of child soldiers in northern Uganda and elsewhere in the world. Apart from providing information to the existing body of research, future areas of proposed research are also outlined.
- Full Text:
- Date Issued: 2014
An architecutre for the effective use of mobile devices in supporting contact learning
- Authors: Alnseerat, Nemr
- Date: 2014
- Subjects: Mobile communication systems in education , Educational technology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10490 , http://hdl.handle.net/10948/d1020079
- Description: The features and capacities of mobile devices offer a wide range of significant opportunities for providing learning content in workplaces and educational institutions. This new approach of teaching, called mobile learning, allows for the delivery of learning content on the move at any time. Mobile learning supports learning by producing learning content to learners in a modern and acceptable way. The number of mobile learning applications has increased rapidly in educational environments. There are, however, limited mobile learning applications that take advantage of mobile devices to support contact learning in the classroom environment. The aim of this research was to design a mobile learning architecture to effectively support contact learning in the classroom. The researcher investigated the historical and theoretical background of mobile learning and reported these findings. This included an overview of existing mobile learning architectures. After identifying their limitations, the researcher designed the Contact Instruction Mobile Learning Architecture (CIMLA) to facilitate the use of mobile devices in the classroom. The researcher developed the LiveLearning prototype based on the proposed architecture as a proof of concept. He conducted a usability evaluation in order to determine the usability of LiveLearning. The results indicated that the LiveLearning prototype is effective in supporting contact learning in the classroom.
- Full Text:
- Date Issued: 2014
- Authors: Alnseerat, Nemr
- Date: 2014
- Subjects: Mobile communication systems in education , Educational technology
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10490 , http://hdl.handle.net/10948/d1020079
- Description: The features and capacities of mobile devices offer a wide range of significant opportunities for providing learning content in workplaces and educational institutions. This new approach of teaching, called mobile learning, allows for the delivery of learning content on the move at any time. Mobile learning supports learning by producing learning content to learners in a modern and acceptable way. The number of mobile learning applications has increased rapidly in educational environments. There are, however, limited mobile learning applications that take advantage of mobile devices to support contact learning in the classroom environment. The aim of this research was to design a mobile learning architecture to effectively support contact learning in the classroom. The researcher investigated the historical and theoretical background of mobile learning and reported these findings. This included an overview of existing mobile learning architectures. After identifying their limitations, the researcher designed the Contact Instruction Mobile Learning Architecture (CIMLA) to facilitate the use of mobile devices in the classroom. The researcher developed the LiveLearning prototype based on the proposed architecture as a proof of concept. He conducted a usability evaluation in order to determine the usability of LiveLearning. The results indicated that the LiveLearning prototype is effective in supporting contact learning in the classroom.
- Full Text:
- Date Issued: 2014
An information services framework for commercial extension services
- Authors: Simpson, Antony Paul
- Date: 2014
- Subjects: Agricultural extension work , Business networks , Information resources management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8575 , vital:26408
- Description: The first of the eight United Nations Millennium Development Goals for 2015 is to “Eradicate Extreme Poverty and Hunger”. Achieving this goal would be aided by having an effective and productive agricultural community. Agricultural organisations assist producers to be more effective in their operation through Commercial Extension Services (CES). Through CES, producers are advised and educated about new agricultural practices, techniques and products. A key component of CES is the provision of relevant information to producers. The problem this research addressed was that producers experience difficulty in accessing the information they require in a timeous, relevant and personalised manner. No suitable framework was found for agricultural organisations to use when designing and implementing an Information Services Platform. The main research objective was to develop and evaluate an Information Services Framework (ISF) for organisations offering information as a CES. The research methodology used to achieve this objective was Design Science Research (DSR). DSR is an iterative methodology with three cycles, namely the relevance, the design and the rigor cycles. The relevance cycle was used to acquire the information required to inform the design cycle. The information was collected by using literature research and empirical studies. The first study, the Producer Information Requirements Survey (PIRS) sought to determine the information requirements of grain producers and was conducted by interviewing grain producers in the Swartland region of South Africa. The second study, the Internet and Mobile Device Usage Survey (IMDUS) investigated the use of the Internet and mobile devices amongst South African producers by means of a national on-line survey. The quantitative and qualitative results of the analysis were used during the design phase to develop the ISF. The design phase of DSR process led to the creation of an ISF for providing Information as a Service (IaaS) in CES. The framework allows for information services to be provided in a manner and form customised to an individual producer’s preferences. The foundation of the framework is that information can be sourced from various sources, internal or external to the organisation and distributed to producers by using a unified platform. During the research, an agricultural organisation, BKB GrainCo used the proposed ISF to develop an Information Services Platform (ISP) to provide information to its producers. BKB GrainCo’s development process included two evaluations. The first evaluation, the Information Preferences Prototype Survey, was intended to test a key component of the framework, the nformation Preferences Profile. The Information Preferences Profile was conceptualized following the PIRS. In the PIRS it was determined that individual producers would prefer to specify what information they would receive, when they required it and have it delivered by using a medium of their choice. The second evaluation of the design phase was a Usability Study. The Usability Study was intended to test the functionality of the system across various technologies. The rigor cycle, following the implementation of BKB GrainCo’s ISP, contained the main evaluation, the Information Services Platform Evaluation. The evaluation was used to test the impact of BKB GrainCo’s ISP on perception of received service. The evaluation used a standardised version of the standardised SERVQUAL instrument specifically adapted in this research to measure the provision of IaaS. The results obtained during the evaluation indicated that the BKB GrainCo’s Information Services Platform was found to be valued by producers and improved the communication services of agricultural organisations. It was inferred from the successful implementation of BKB GrainCo’s ISP and the positive response from producers, after the evaluations, that the developed ISF was suitable for an agricultural organisation to provide CES. The theoretical contributions included underpinning the concept of CES in terms of stakeholder theory. Its underpinning provides justification for agricultural organisations to improve CES – including the provision of information. A second theoretical contribution was the extension of SERVQUAL as an IS theory by developing and validating a dimension designed to test the provision of IaaS. Providing producers with accurate and reliable personalised information has the capacity to improve producers’ ability to make informed decisions. Informed decision making will contribute to having an effective and productive agricultural community; resulting in improvement of agricultural output and contributing to food security and job creation. Improved agricultural output, better food security and job creation are aspects which will contribute toward the attainment of the first of eight United Nations Millennium Development Goals for 2015, which is to “Eradicate Extreme Poverty and Hunger”.
- Full Text:
- Date Issued: 2014
- Authors: Simpson, Antony Paul
- Date: 2014
- Subjects: Agricultural extension work , Business networks , Information resources management
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/8575 , vital:26408
- Description: The first of the eight United Nations Millennium Development Goals for 2015 is to “Eradicate Extreme Poverty and Hunger”. Achieving this goal would be aided by having an effective and productive agricultural community. Agricultural organisations assist producers to be more effective in their operation through Commercial Extension Services (CES). Through CES, producers are advised and educated about new agricultural practices, techniques and products. A key component of CES is the provision of relevant information to producers. The problem this research addressed was that producers experience difficulty in accessing the information they require in a timeous, relevant and personalised manner. No suitable framework was found for agricultural organisations to use when designing and implementing an Information Services Platform. The main research objective was to develop and evaluate an Information Services Framework (ISF) for organisations offering information as a CES. The research methodology used to achieve this objective was Design Science Research (DSR). DSR is an iterative methodology with three cycles, namely the relevance, the design and the rigor cycles. The relevance cycle was used to acquire the information required to inform the design cycle. The information was collected by using literature research and empirical studies. The first study, the Producer Information Requirements Survey (PIRS) sought to determine the information requirements of grain producers and was conducted by interviewing grain producers in the Swartland region of South Africa. The second study, the Internet and Mobile Device Usage Survey (IMDUS) investigated the use of the Internet and mobile devices amongst South African producers by means of a national on-line survey. The quantitative and qualitative results of the analysis were used during the design phase to develop the ISF. The design phase of DSR process led to the creation of an ISF for providing Information as a Service (IaaS) in CES. The framework allows for information services to be provided in a manner and form customised to an individual producer’s preferences. The foundation of the framework is that information can be sourced from various sources, internal or external to the organisation and distributed to producers by using a unified platform. During the research, an agricultural organisation, BKB GrainCo used the proposed ISF to develop an Information Services Platform (ISP) to provide information to its producers. BKB GrainCo’s development process included two evaluations. The first evaluation, the Information Preferences Prototype Survey, was intended to test a key component of the framework, the nformation Preferences Profile. The Information Preferences Profile was conceptualized following the PIRS. In the PIRS it was determined that individual producers would prefer to specify what information they would receive, when they required it and have it delivered by using a medium of their choice. The second evaluation of the design phase was a Usability Study. The Usability Study was intended to test the functionality of the system across various technologies. The rigor cycle, following the implementation of BKB GrainCo’s ISP, contained the main evaluation, the Information Services Platform Evaluation. The evaluation was used to test the impact of BKB GrainCo’s ISP on perception of received service. The evaluation used a standardised version of the standardised SERVQUAL instrument specifically adapted in this research to measure the provision of IaaS. The results obtained during the evaluation indicated that the BKB GrainCo’s Information Services Platform was found to be valued by producers and improved the communication services of agricultural organisations. It was inferred from the successful implementation of BKB GrainCo’s ISP and the positive response from producers, after the evaluations, that the developed ISF was suitable for an agricultural organisation to provide CES. The theoretical contributions included underpinning the concept of CES in terms of stakeholder theory. Its underpinning provides justification for agricultural organisations to improve CES – including the provision of information. A second theoretical contribution was the extension of SERVQUAL as an IS theory by developing and validating a dimension designed to test the provision of IaaS. Providing producers with accurate and reliable personalised information has the capacity to improve producers’ ability to make informed decisions. Informed decision making will contribute to having an effective and productive agricultural community; resulting in improvement of agricultural output and contributing to food security and job creation. Improved agricultural output, better food security and job creation are aspects which will contribute toward the attainment of the first of eight United Nations Millennium Development Goals for 2015, which is to “Eradicate Extreme Poverty and Hunger”.
- Full Text:
- Date Issued: 2014
An investigation into the use of a ceramifiable Ethylene Vinyl Acetate (EVA) co-polymer formulation to aid flame retardency in electrical cables
- Authors: Bambalaza, Sonwabo Elvis
- Date: 2014
- Subjects: Vinyl acetate , Polymeric composites , Inorganic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10433 , http://hdl.handle.net/10948/d1020159
- Description: The concept of a unique ceramifiable Ethylene vinyl acetate (EVA) based polymer composite was based on the incorporation of inorganic compounds such as aluminium hydroxide, calcium carbonate, muscovite mica, and calcined kaolinite within a 95 percent EVA/ 5 percent Polydimethylsiloxane (PDMS) polymer matrix such tha t upon heating to elevated temperatures of about 1000 oC, a solid end-product with ceramic-like properties would be formed. The ceramifiable EVA based polymer composite was developed to be used as electric cable insulation or sheath as the formation of a ceramic based material at elevated temperatures would provide flame retardant properties during fire situations. The flame retardant properties at elevated temperatures would ensure that the insulation remains at such temperatures due to some of the properties of the resultant ceramic such as reasonably high flexural strength, high thermal stability, non-reactivity and high melting point. During a fire this would ensure that flames would not be propagated along the length of the cable and also protect the underlying conducting wires from being exposed to the high temperatures of the fire. Its application as a cable insulation also required that the material functions as a cable insulator under ambient temperature conditions where the ceramifiable polymer composite should retain certain polymer properties such as the post-cure tensile strength (MPa), degree of polymer elongation (percent), thermal expansion, thermal slacking, limited oxygen index and electrical insulation. This study made use of a composite experimental design approach that would allow for the optimization of the amounts of the additives in the ceramifiable polymer composite giving both the desired mechanical properties of the material under normal operating temperatures as a polymer and also as a ceramic once exposed to elevated temperatures. The optimization of additives used in the ceramifiable polymer composite was done by using a D-optimal mixture design of experiments (DoE) which was analyzed by multiple linear regression.
- Full Text:
- Date Issued: 2014
- Authors: Bambalaza, Sonwabo Elvis
- Date: 2014
- Subjects: Vinyl acetate , Polymeric composites , Inorganic compounds
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10433 , http://hdl.handle.net/10948/d1020159
- Description: The concept of a unique ceramifiable Ethylene vinyl acetate (EVA) based polymer composite was based on the incorporation of inorganic compounds such as aluminium hydroxide, calcium carbonate, muscovite mica, and calcined kaolinite within a 95 percent EVA/ 5 percent Polydimethylsiloxane (PDMS) polymer matrix such tha t upon heating to elevated temperatures of about 1000 oC, a solid end-product with ceramic-like properties would be formed. The ceramifiable EVA based polymer composite was developed to be used as electric cable insulation or sheath as the formation of a ceramic based material at elevated temperatures would provide flame retardant properties during fire situations. The flame retardant properties at elevated temperatures would ensure that the insulation remains at such temperatures due to some of the properties of the resultant ceramic such as reasonably high flexural strength, high thermal stability, non-reactivity and high melting point. During a fire this would ensure that flames would not be propagated along the length of the cable and also protect the underlying conducting wires from being exposed to the high temperatures of the fire. Its application as a cable insulation also required that the material functions as a cable insulator under ambient temperature conditions where the ceramifiable polymer composite should retain certain polymer properties such as the post-cure tensile strength (MPa), degree of polymer elongation (percent), thermal expansion, thermal slacking, limited oxygen index and electrical insulation. This study made use of a composite experimental design approach that would allow for the optimization of the amounts of the additives in the ceramifiable polymer composite giving both the desired mechanical properties of the material under normal operating temperatures as a polymer and also as a ceramic once exposed to elevated temperatures. The optimization of additives used in the ceramifiable polymer composite was done by using a D-optimal mixture design of experiments (DoE) which was analyzed by multiple linear regression.
- Full Text:
- Date Issued: 2014
Analysis of the interaction between recombinant human Beta2 integrin I-domains and CD23
- Authors: Sprong, Kaitlin
- Date: 2014
- Subjects: Immune response -- Regulation , Immunoglobulins , CD23 antigen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10362 , http://hdl.handle.net/10948/d1021078
- Description: In order to further elucidate the interaction between CD23 and β2 integrins (CD11b/CD18) the following objectives were established: Expression and purification of CD11b I-domain as a GST-fusion protein using Escherichia coli; Cloning, synthesis and expression of CD18 I-Like domain.CD11b I-domain has previously been expressed as a GST-fusion protein (Daniels, 2010) and consequently led to comparable expression of CD18 I-like domain as a GST-fusion protein; Preparation of two site-directed mutants of CD18 I-Like domain in order to study the function of the serine residue involved in the S116P mutation. The serine was mutated to proline, as in LAD patients, as well as alanine, a non-polar alternative, in order to contrast and compare binding characteristics. Expression, refolding and purification of sCD23, and a double mutatedsCD23 (RKΔAA) from E. coli; This was performed according to the method described by Daniels et al. (2005); Investigation of the CD23-CD11b I-like domain interaction through surface plasmon resonance spectroscopy.
- Full Text:
- Date Issued: 2014
- Authors: Sprong, Kaitlin
- Date: 2014
- Subjects: Immune response -- Regulation , Immunoglobulins , CD23 antigen
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10362 , http://hdl.handle.net/10948/d1021078
- Description: In order to further elucidate the interaction between CD23 and β2 integrins (CD11b/CD18) the following objectives were established: Expression and purification of CD11b I-domain as a GST-fusion protein using Escherichia coli; Cloning, synthesis and expression of CD18 I-Like domain.CD11b I-domain has previously been expressed as a GST-fusion protein (Daniels, 2010) and consequently led to comparable expression of CD18 I-like domain as a GST-fusion protein; Preparation of two site-directed mutants of CD18 I-Like domain in order to study the function of the serine residue involved in the S116P mutation. The serine was mutated to proline, as in LAD patients, as well as alanine, a non-polar alternative, in order to contrast and compare binding characteristics. Expression, refolding and purification of sCD23, and a double mutatedsCD23 (RKΔAA) from E. coli; This was performed according to the method described by Daniels et al. (2005); Investigation of the CD23-CD11b I-like domain interaction through surface plasmon resonance spectroscopy.
- Full Text:
- Date Issued: 2014
Analysis of the tectonic and basin evolution of the seychelles microcontinent during the mesozoic to cenozoic, based on seismic and well data
- Authors: Mondon, Jean-Luc Andre
- Date: 2014
- Subjects: Sedimentation and deposition , Gondwana (Continent) , Sedimentary basins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4386 , vital:20593
- Description: The Seychelles Microcontinent (SMc) is a fragment of continental lithosphere that experienced multiple phases of rifting and thermal subsidence during its isolation and submergence within the Indian Ocean. Originally part of central Gondwana, along with India and Madagascar, the SMc first emerged during Mesozoic fragmentation of Gondwana (ca. 220 – 180 Ma) along a complex rifted margin. Fragmentation involved three major rift phases, viz.: 1) Middle Triassic – Middle Jurassic (Rift I), associated with the “Karoo rifts” and break-up between [India-Madagascar-Seychelles] and East Africa; 2) Middle Jurassic – Early Cretaceous (Rift II), associated with the rifting and break-up of Madagascar from [India-Seychelles]; 3) Late Cretaceous (Rift III), associated with the rifting and final break-away of the SMc from India. In this study, the tectonic and sedimentary history of the SMc is analysed using 2D seismic reflection datasets and three exploration wells. Seismic to well-log correlations provide a chrono-stratigraphic framework that identifies seven sequences from the Middle Triassic to the Paleogene. This also identified horst and graben structures related to the extensional tectonics and thermal subsidence of this continental fragment. The latter is reflected also in changes of its litho-facies preserved on the SMc, from terrestrial to marine. The oldest sedimentary rocks identified on the SMc are Middle Triassic organic rich claystones (Sequence 7, Rift I), which grade upwards into alternating Upper Triassic sandstones and mudstones (Sequence 6, Rift I) followed by upward coarsening Lower Jurassic mudstones to sandstone units (Sequence 5, Rift I). These sequences are interpreted as lacustrine facies that evolved into fluvial channel migration facies and finally into progradational delta front facies. Sequence 5 is overlain by Middle Jurassic oolitic limestones that grade upwards into organic rich mudstones (Sequence 4, thermal subsidence after Rift I); the latter are interpreted as restricted-marginal marine deposits. Following Sequence 4, separated by a major break-up unconformity (BU), are the Upper Cretaceous open marine deposits comprising limestones, claystones and sandstones, and terminated with basaltic volcanics (ca. 66 Ma) prior to the separation of the SMc from India (Sequence 3, Rift III). This is overlain by the post-rift – thermal subsidence sequences comprising open marine claystones and shelf limestones (Sequence 2) followed by a sequence of shelf limestones (Sequence 1) that form the present carbonate platform, the Seychelles Plateau that lies approximately 200 m below the present sea-level. Backstripping and subsidence analysis quantifies 3 stages of subsidence; Phase A: Slow subsidence (ca. 5-20 m/Ma), from the Middle Jurassic to the Upper Cretaceous that terminated during a major marine transgression during ingression of the Tethys Sea between East Africa and [Madagascar-Seychelles-India]. This created marine conditions and the subsequent deposition of Sequences 4 and 3; Phase B: Accelerated subsidence (ca. 35-60 m/Ma) recorded throughout the Paleocene to the middle Eocene leading to deeper marine conditions and the subsequent deposition of Sequence 2; and Phase C: Reduced subsidence (ca. 10-30 m/Ma) following the interaction between the Carlsberg Ridge and the Reunion hotspot (ca. 55 Ma) that possibly introduced a reduction in subsidence and the subsequent deposition of Sequence 1 as the SMc drifted and thermally subsided to its submerged present location, and is now dominated mainly by marine carbonates. The effects of the Madagascar and Seychelles/India separation (ca. 84 Ma) are not observed in the subsidence analysis, possibly because it involved transcurrent-rotational movement between the two plates over a short period of time.
- Full Text:
- Date Issued: 2014
- Authors: Mondon, Jean-Luc Andre
- Date: 2014
- Subjects: Sedimentation and deposition , Gondwana (Continent) , Sedimentary basins
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/4386 , vital:20593
- Description: The Seychelles Microcontinent (SMc) is a fragment of continental lithosphere that experienced multiple phases of rifting and thermal subsidence during its isolation and submergence within the Indian Ocean. Originally part of central Gondwana, along with India and Madagascar, the SMc first emerged during Mesozoic fragmentation of Gondwana (ca. 220 – 180 Ma) along a complex rifted margin. Fragmentation involved three major rift phases, viz.: 1) Middle Triassic – Middle Jurassic (Rift I), associated with the “Karoo rifts” and break-up between [India-Madagascar-Seychelles] and East Africa; 2) Middle Jurassic – Early Cretaceous (Rift II), associated with the rifting and break-up of Madagascar from [India-Seychelles]; 3) Late Cretaceous (Rift III), associated with the rifting and final break-away of the SMc from India. In this study, the tectonic and sedimentary history of the SMc is analysed using 2D seismic reflection datasets and three exploration wells. Seismic to well-log correlations provide a chrono-stratigraphic framework that identifies seven sequences from the Middle Triassic to the Paleogene. This also identified horst and graben structures related to the extensional tectonics and thermal subsidence of this continental fragment. The latter is reflected also in changes of its litho-facies preserved on the SMc, from terrestrial to marine. The oldest sedimentary rocks identified on the SMc are Middle Triassic organic rich claystones (Sequence 7, Rift I), which grade upwards into alternating Upper Triassic sandstones and mudstones (Sequence 6, Rift I) followed by upward coarsening Lower Jurassic mudstones to sandstone units (Sequence 5, Rift I). These sequences are interpreted as lacustrine facies that evolved into fluvial channel migration facies and finally into progradational delta front facies. Sequence 5 is overlain by Middle Jurassic oolitic limestones that grade upwards into organic rich mudstones (Sequence 4, thermal subsidence after Rift I); the latter are interpreted as restricted-marginal marine deposits. Following Sequence 4, separated by a major break-up unconformity (BU), are the Upper Cretaceous open marine deposits comprising limestones, claystones and sandstones, and terminated with basaltic volcanics (ca. 66 Ma) prior to the separation of the SMc from India (Sequence 3, Rift III). This is overlain by the post-rift – thermal subsidence sequences comprising open marine claystones and shelf limestones (Sequence 2) followed by a sequence of shelf limestones (Sequence 1) that form the present carbonate platform, the Seychelles Plateau that lies approximately 200 m below the present sea-level. Backstripping and subsidence analysis quantifies 3 stages of subsidence; Phase A: Slow subsidence (ca. 5-20 m/Ma), from the Middle Jurassic to the Upper Cretaceous that terminated during a major marine transgression during ingression of the Tethys Sea between East Africa and [Madagascar-Seychelles-India]. This created marine conditions and the subsequent deposition of Sequences 4 and 3; Phase B: Accelerated subsidence (ca. 35-60 m/Ma) recorded throughout the Paleocene to the middle Eocene leading to deeper marine conditions and the subsequent deposition of Sequence 2; and Phase C: Reduced subsidence (ca. 10-30 m/Ma) following the interaction between the Carlsberg Ridge and the Reunion hotspot (ca. 55 Ma) that possibly introduced a reduction in subsidence and the subsequent deposition of Sequence 1 as the SMc drifted and thermally subsided to its submerged present location, and is now dominated mainly by marine carbonates. The effects of the Madagascar and Seychelles/India separation (ca. 84 Ma) are not observed in the subsidence analysis, possibly because it involved transcurrent-rotational movement between the two plates over a short period of time.
- Full Text:
- Date Issued: 2014
Biofuel, land-use tradeoffs and livelihoods in Southern Africa
- Authors: Von Maltitz, Graham Paul
- Date: 2014
- Subjects: Biomass energy -- Climatic factors -- Africa, Southern , Land use -- Environmental aspects , Jatropha -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10643 , http://hdl.handle.net/10948/d1021005
- Description: The rapid expansion of biofuel projects in southern Africa creates an opportune issue against which to examine land-use tradeoffs within the areas of customary land tenure. For this an ecosystems services approach is used. Jatropha curcas (L), a perennial oilseed plant which has been the key focus of most of the region’s biofuel expansion to date is used as the focus biofuel crop for which case study data were obtained from Malawi, Mozambique, Zambia and South Africa. Despite the initial enthusiasm for jatropha, most projects have proven less successful than hoped, and many have collapsed. A few are, however, still showing signs of possible success and it is two of these that form the basis of the case studies. Hugely complex tradeoffs are involved when considering biofuel as a land-use option for communal areas. They range from global impacts such as biodiversity and global climate forcing, through national concerns of rural development, national food security and national fuel security, to local household concerns around improving livelihoods. Land that is converted to biofuel needs to be removed from some previous use, and in the southern African case it is typically woodlands and the multitude of services they provide, that suffer. The nature of the tradeoffs and the people affected change over the scale under consideration. For the local farmer it is only the local issues that are of concern, but national and global forces will change the policy environment and lead to new types of development such as biofuels. Change is inevitable, and in all developments there are likely to be both winners and losers. It is clear that the impacts arising from biofuel are situation dependent, and each community and location has unique social and environmental considerations that need to be taken into account. In the case of jatropha the final realised yield and the economic returns that this can generate, will be of critical importance and remain one of the main uncertainties. There are promising signs that under certain circumstances the balance of benefits from jatropha biofuel may be positive, but if implemented incorrectly or in the wrong place, there is extensive evidence of total project failure. It is clear that evidence-based data and assessment tools are needed to assist communities, developers and government departments to make sound decisions around biofuel (or other land-use based) development. A number of such tools are suggested in the thesis. Both the use of large-scale plantations or small-scale farmer centred projects have their advantages and disadvantages. It is probable that in the correct circumstances either can work. However, large-scale plantations can have huge negative social and environmental consequences if poorly implemented. Small-scale projects, though improving livelihoods, are unlikely to take the farmers out of poverty. Tradeoffs from any land-use change are inevitable. Empirical data on biofuel impacts on the environment and society are needed for the development of sound policy. A favourable policy environment can ensure that positive benefits from biofuel are obtained, whilst minimising negative impacts. To develop this policy means that southern African countries will have to clearly understand what they wish to achieve from biofuel, as well as having a clear understanding of impacts from biofuel implementation. Sound scientific knowledge needs to underpin this process. For instance governments may wish to increase the ratio of small-scale to large-scale plantation to increase the developmental benefits, ensure biofuel is used to promote national fuel security rather than being exported, or develop a medium-scale farming sector which can help move farmers out of poverty and assist in developing a market surplus of agricultural commodities. Analysing impacts from biofuel expansion is a complex and multi-dimensional problem and as such will require multi-criteria analysis tools to develop solutions. Global, national and local tradeoffs must all be considered. In addition a wide range of stakeholders are involved and participatory processes may be needed to capture their inputs. Tools to better analyse impacts, specifically at the local level are needed. These local results need to feed into national level economic assessments. The cost of biofuel introduction should be considered against the costs of not implementing biofuel, realising that doing nothing also has a cost and long-term impact. Third-party certification provides a useful tool for shifting costs of ensuring compliance with social and environmental legislation, from the state to biofuel companies. In addition ongoing monitoring and evaluation of existing projects is needed to learn from successes and failures, to identify unintended consequences, and to increase the resilience of projects, community livelihoods and the national economy. This will have to be supplemented with additional focused and ongoing research.
- Full Text:
- Date Issued: 2014
- Authors: Von Maltitz, Graham Paul
- Date: 2014
- Subjects: Biomass energy -- Climatic factors -- Africa, Southern , Land use -- Environmental aspects , Jatropha -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10643 , http://hdl.handle.net/10948/d1021005
- Description: The rapid expansion of biofuel projects in southern Africa creates an opportune issue against which to examine land-use tradeoffs within the areas of customary land tenure. For this an ecosystems services approach is used. Jatropha curcas (L), a perennial oilseed plant which has been the key focus of most of the region’s biofuel expansion to date is used as the focus biofuel crop for which case study data were obtained from Malawi, Mozambique, Zambia and South Africa. Despite the initial enthusiasm for jatropha, most projects have proven less successful than hoped, and many have collapsed. A few are, however, still showing signs of possible success and it is two of these that form the basis of the case studies. Hugely complex tradeoffs are involved when considering biofuel as a land-use option for communal areas. They range from global impacts such as biodiversity and global climate forcing, through national concerns of rural development, national food security and national fuel security, to local household concerns around improving livelihoods. Land that is converted to biofuel needs to be removed from some previous use, and in the southern African case it is typically woodlands and the multitude of services they provide, that suffer. The nature of the tradeoffs and the people affected change over the scale under consideration. For the local farmer it is only the local issues that are of concern, but national and global forces will change the policy environment and lead to new types of development such as biofuels. Change is inevitable, and in all developments there are likely to be both winners and losers. It is clear that the impacts arising from biofuel are situation dependent, and each community and location has unique social and environmental considerations that need to be taken into account. In the case of jatropha the final realised yield and the economic returns that this can generate, will be of critical importance and remain one of the main uncertainties. There are promising signs that under certain circumstances the balance of benefits from jatropha biofuel may be positive, but if implemented incorrectly or in the wrong place, there is extensive evidence of total project failure. It is clear that evidence-based data and assessment tools are needed to assist communities, developers and government departments to make sound decisions around biofuel (or other land-use based) development. A number of such tools are suggested in the thesis. Both the use of large-scale plantations or small-scale farmer centred projects have their advantages and disadvantages. It is probable that in the correct circumstances either can work. However, large-scale plantations can have huge negative social and environmental consequences if poorly implemented. Small-scale projects, though improving livelihoods, are unlikely to take the farmers out of poverty. Tradeoffs from any land-use change are inevitable. Empirical data on biofuel impacts on the environment and society are needed for the development of sound policy. A favourable policy environment can ensure that positive benefits from biofuel are obtained, whilst minimising negative impacts. To develop this policy means that southern African countries will have to clearly understand what they wish to achieve from biofuel, as well as having a clear understanding of impacts from biofuel implementation. Sound scientific knowledge needs to underpin this process. For instance governments may wish to increase the ratio of small-scale to large-scale plantation to increase the developmental benefits, ensure biofuel is used to promote national fuel security rather than being exported, or develop a medium-scale farming sector which can help move farmers out of poverty and assist in developing a market surplus of agricultural commodities. Analysing impacts from biofuel expansion is a complex and multi-dimensional problem and as such will require multi-criteria analysis tools to develop solutions. Global, national and local tradeoffs must all be considered. In addition a wide range of stakeholders are involved and participatory processes may be needed to capture their inputs. Tools to better analyse impacts, specifically at the local level are needed. These local results need to feed into national level economic assessments. The cost of biofuel introduction should be considered against the costs of not implementing biofuel, realising that doing nothing also has a cost and long-term impact. Third-party certification provides a useful tool for shifting costs of ensuring compliance with social and environmental legislation, from the state to biofuel companies. In addition ongoing monitoring and evaluation of existing projects is needed to learn from successes and failures, to identify unintended consequences, and to increase the resilience of projects, community livelihoods and the national economy. This will have to be supplemented with additional focused and ongoing research.
- Full Text:
- Date Issued: 2014
Biospeciation and antidiabetic effects of oxidovanadium(IV) complexes
- Authors: Ugirinema, Vital
- Date: 2014
- Subjects: Vanadium compounds , Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10442 , http://hdl.handle.net/10948/d1020973
- Description: The syntheses of bis(1R-imidazole-2/4-carboxylato)oxidovanadium(IV) complexes was successfully carried out and the complexes were isolated in the solid state. The coordinated water was confirmed by elemental analyses, and single crystal XRD. The complexes were therefore distorted octahedral rather than square planar due to the coordination of water at the sixth position. The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), and phosphate (Phos)] and high molecular weight (HMM) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid base titrations under oxygen and carbon dioxide–free conditions. The data obtained from these titrations was used to calculate the binary and ternary stability constants using the programme HYPERQUAD. The overall stability constants for VO2+-L-Ox system (log β1111 = 18.9, 18.79 and 19.86), VO2+-L-Lact system (log β1111 = 21.83, 20.98 and 22.86), and VO2+-L-Phos system (log β1111 = 27.35, 24.16 and 27.42) (for L= Im4COOH, Im2COOH and MeIm2COOH, respectively) were obtained. The species distribution diagrams showed that under physiological pH the following ternary and quaternary species; [(VO)L(bL)], and [VO(L)(bL)(OH)], would dominate provided that the competition with serum proteins is not too strong. These species were also confirmed by HPLC, LC-MS and EPR. The overall stability constants for the VO2+-L-HSA system (log β2,1,1,0 = 24.3, 23.7 and 24.7), and for the VO2+-L-hTf system (log β2,2,1,0 = 31.1, 30.8, 36.4 for L = Im4COOH, Im2COOH and MeIm2COOH, respectively), suggesting stronger binding of transferrin. The formation constants for the formation of binary (VO(IV) and the proteins) were 9.1 and 13 for log β11, and 20.9 and 25.2 for β12, for human serum albumin and human serum transferrin respectively. The species distribution diagrams for the proteins (HMM) with oxidovanadium(IV) under physiological pH was dominated by VO(HMM)2, VOL(HMM) for unsubstituted Im4COOH and Im2COOH, however, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH, were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by HPLC, MALDI-TOF-MS and EPR. The glucose stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at 1μM concentration which was established through cytotoxicity studies via the MTT assay. The vanadium salt (VOSO4), cationic vanadium(IV) complex ([VO(MeImCH2OH)2]2+) were also included in the GSIS study in addition to the three neutral complexes [VO(Im4COO)2, VO(Im2COO)2 and VO(MeIm2COO)2] for comparison. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic complex and the vanadium salt.
- Full Text:
- Date Issued: 2014
- Authors: Ugirinema, Vital
- Date: 2014
- Subjects: Vanadium compounds , Diabetes
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10442 , http://hdl.handle.net/10948/d1020973
- Description: The syntheses of bis(1R-imidazole-2/4-carboxylato)oxidovanadium(IV) complexes was successfully carried out and the complexes were isolated in the solid state. The coordinated water was confirmed by elemental analyses, and single crystal XRD. The complexes were therefore distorted octahedral rather than square planar due to the coordination of water at the sixth position. The reaction of the vanadyl ion (VO2+) with imidazole-4-carboxylic acid (Im4COOH), imidazole-2-carboxylic acid (Im2COOH) and methylimidazole-2-carboxylic acid (MeIm2COOH), respectively, in the presence of small bioligands (bL) [oxalate (Ox), lactate (Lact), and phosphate (Phos)] and high molecular weight (HMM) human serum proteins [albumin (HSA) and transferrin (hTf)] were studied in aqueous solution using potentiometric acid base titrations under oxygen and carbon dioxide–free conditions. The data obtained from these titrations was used to calculate the binary and ternary stability constants using the programme HYPERQUAD. The overall stability constants for VO2+-L-Ox system (log β1111 = 18.9, 18.79 and 19.86), VO2+-L-Lact system (log β1111 = 21.83, 20.98 and 22.86), and VO2+-L-Phos system (log β1111 = 27.35, 24.16 and 27.42) (for L= Im4COOH, Im2COOH and MeIm2COOH, respectively) were obtained. The species distribution diagrams showed that under physiological pH the following ternary and quaternary species; [(VO)L(bL)], and [VO(L)(bL)(OH)], would dominate provided that the competition with serum proteins is not too strong. These species were also confirmed by HPLC, LC-MS and EPR. The overall stability constants for the VO2+-L-HSA system (log β2,1,1,0 = 24.3, 23.7 and 24.7), and for the VO2+-L-hTf system (log β2,2,1,0 = 31.1, 30.8, 36.4 for L = Im4COOH, Im2COOH and MeIm2COOH, respectively), suggesting stronger binding of transferrin. The formation constants for the formation of binary (VO(IV) and the proteins) were 9.1 and 13 for log β11, and 20.9 and 25.2 for β12, for human serum albumin and human serum transferrin respectively. The species distribution diagrams for the proteins (HMM) with oxidovanadium(IV) under physiological pH was dominated by VO(HMM)2, VOL(HMM) for unsubstituted Im4COOH and Im2COOH, however, for the N-substituted MeIm2COOH, the species distribution diagrams under physiological pH, were dominated by VOL2, VO(HMM)2 and VO2L2(HMM). These species were further confirmed by HPLC, MALDI-TOF-MS and EPR. The glucose stimulated insulin secretion (GSIS) action of the complexes was investigated using INS-1E cells at 1μM concentration which was established through cytotoxicity studies via the MTT assay. The vanadium salt (VOSO4), cationic vanadium(IV) complex ([VO(MeImCH2OH)2]2+) were also included in the GSIS study in addition to the three neutral complexes [VO(Im4COO)2, VO(Im2COO)2 and VO(MeIm2COO)2] for comparison. The neutral complexes, especially VO(MeIm2COO)2, showed promising results in the stimulation of insulin secretion than the cationic complex and the vanadium salt.
- Full Text:
- Date Issued: 2014
Causal determinants of the public's attitudes towards hunting as a basis for strategies to improve the social legitimacy of hunting
- Coetzer, Wentzel Christoffel
- Authors: Coetzer, Wentzel Christoffel
- Date: 2014
- Subjects: Hunting -- South Africa , Wildlife management -- South Africa , Wildlife conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10759 , http://hdl.handle.net/10948/d1021164
- Description: It is widely acknowledged that the organised wildlife and hunting industry in South Africa contributes significantly to the country’s economy, as well as to the effective management and conservation of wildlife on privately owned land. Despite this, hunting has come under increasing attack by anti-hunting proponents who wish to bring a ban on hunting. A number of broad shifts across society at large and lobbying against hunting by anti-hunting proponents have given rise to legitimate concerns regarding the social acceptability of hunting. To maintain the social legitimacy of hunting, it is imperative to put strategies in place to actively broaden the base of public acceptance of hunting. Towards this aim, this study is an empirical investigation of the causal determinants of the public’s attitudes towards hunting and of the implications it holds for improving the social legitimacy of hunting. The study commenced by building a sound theoretical foundation from the available literature on the measurement of attitudes, the structure and formation of attitudes, the instrumental and experiential aspects of attitudes, attitudinal ambivalence, the psychology of strong attitudes, as well as the phenomenon of cognitive dissonance. Thereafter, the study turned to identify an adequate and empirically valid research approach for investigating attitudes and its causal determinants. A popular attitude theory in social psychology, namely the theory of reasoned action, was identified as a suitable conceptual framework for conducting this study. According to the reasoned action model, the salient behavioural beliefs people associate with a particular behaviour form the informational foundation (or cognitive foundation) on which their attitudes towards the behaviour are based. More specifically, the model suggests that peoples’ overall attitude towards a behaviour is a function of their perceived probability that a behaviour will produce certain outcomes (belief strength), as well as the degree to which they judge the perceived outcomes of the behaviour as positive or negative (outcome evaluation). The methodological design of the study’s empirical component was strictly based on the standard procedures prescribed by the theory of reasoned action. Two consecutive and methodologically interrelated surveys were conducted amongst members of the public to collect the study’s primary data. The main salient behavioural beliefs on which different attitudes towards hunting are based were identified and further investigated. The results were analysed from the perspective of the theory of reasoned action and a clear understanding of the causal determinants of different attitudes towards hunting were attained. Based on the findings of the study, a number of conclusions and recommendations were made that may guide the development of future strategies to improve the social legitimacy of hunting. Amongst other things, it was suggested that public education programmes should be developed to address the public’s misconceptions of hunting; that public relation campaigns be undertaken to improve the public’s negative image of hunters; and that hunter education programmes be put in place to make hunters aware of the role they could play at community level to improve the social acceptability of hunting. Detailed guidelines regarding the contents of such education programmes and public relation campaigns were provided.
- Full Text:
- Date Issued: 2014
- Authors: Coetzer, Wentzel Christoffel
- Date: 2014
- Subjects: Hunting -- South Africa , Wildlife management -- South Africa , Wildlife conservation -- South Africa
- Language: English
- Type: Thesis , Doctoral , DTech
- Identifier: vital:10759 , http://hdl.handle.net/10948/d1021164
- Description: It is widely acknowledged that the organised wildlife and hunting industry in South Africa contributes significantly to the country’s economy, as well as to the effective management and conservation of wildlife on privately owned land. Despite this, hunting has come under increasing attack by anti-hunting proponents who wish to bring a ban on hunting. A number of broad shifts across society at large and lobbying against hunting by anti-hunting proponents have given rise to legitimate concerns regarding the social acceptability of hunting. To maintain the social legitimacy of hunting, it is imperative to put strategies in place to actively broaden the base of public acceptance of hunting. Towards this aim, this study is an empirical investigation of the causal determinants of the public’s attitudes towards hunting and of the implications it holds for improving the social legitimacy of hunting. The study commenced by building a sound theoretical foundation from the available literature on the measurement of attitudes, the structure and formation of attitudes, the instrumental and experiential aspects of attitudes, attitudinal ambivalence, the psychology of strong attitudes, as well as the phenomenon of cognitive dissonance. Thereafter, the study turned to identify an adequate and empirically valid research approach for investigating attitudes and its causal determinants. A popular attitude theory in social psychology, namely the theory of reasoned action, was identified as a suitable conceptual framework for conducting this study. According to the reasoned action model, the salient behavioural beliefs people associate with a particular behaviour form the informational foundation (or cognitive foundation) on which their attitudes towards the behaviour are based. More specifically, the model suggests that peoples’ overall attitude towards a behaviour is a function of their perceived probability that a behaviour will produce certain outcomes (belief strength), as well as the degree to which they judge the perceived outcomes of the behaviour as positive or negative (outcome evaluation). The methodological design of the study’s empirical component was strictly based on the standard procedures prescribed by the theory of reasoned action. Two consecutive and methodologically interrelated surveys were conducted amongst members of the public to collect the study’s primary data. The main salient behavioural beliefs on which different attitudes towards hunting are based were identified and further investigated. The results were analysed from the perspective of the theory of reasoned action and a clear understanding of the causal determinants of different attitudes towards hunting were attained. Based on the findings of the study, a number of conclusions and recommendations were made that may guide the development of future strategies to improve the social legitimacy of hunting. Amongst other things, it was suggested that public education programmes should be developed to address the public’s misconceptions of hunting; that public relation campaigns be undertaken to improve the public’s negative image of hunters; and that hunter education programmes be put in place to make hunters aware of the role they could play at community level to improve the social acceptability of hunting. Detailed guidelines regarding the contents of such education programmes and public relation campaigns were provided.
- Full Text:
- Date Issued: 2014
Characterization of animal fibres
- Authors: Notayi, Mzwamadoda
- Date: 2014
- Subjects: Animal fibres , Textile fabrics , Animal science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10552 , http://hdl.handle.net/10948/d1020426
- Description: Identification of fibres, particularly in blends, requires knowledge of their characteristics. Individual Identifying features between wool and mohair fibres were investigated in this study using a Scanning Electron Microscope (SEM), Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), Fourier Transform Raman and Atomic Force Microscope (AFM). This study confirmed that wool and mohair can be differentiated and identified in blends using the cuticle scale height (CSH) criterion, wool having an average CSH of 0.6 ± 0.1 μm and mohair having an average CSH of 0.4 ± 0.1 μm. The AFM provided highly reproducible CSH results, which also confirmed the SEM results that indeed wool and mohair could be differentiated using the CSH as criterion. The AFM gave a CSH value of 0.9 ± 0.2 μm for wool and 0.6 ± 0.2 μm for mohair, the difference between the two results being statistically significant according to the student t-test. It has been demonstrated that wool and mohair identification in blends is possible, by using the AFM to measure CSH, although the method is very time consuming and might be expensive. The FTIR-ATR showed similar spectra for wool and mohair fibres, confirming that the two fibre types consist of the same polymer material. Nevertheless, a difference was observed in the ratios of the relative intensities of the amide I (around 1630 cm-1) to the amide II (around 1515cm-1) absorption bands. The FT Raman provided similar spectra for the wool and mohair fibres, although a possible distinguishing feature between the two fibres could be the intensities of the alkyl side chains chemical band near 2940 cm-1 in the spectra of the two fibre types. According to the results obtained in this study, the FTIR-ATR and the FT Raman techniques may have potential for differentiating between wool and mohair but this requires further investigation.
- Full Text:
- Date Issued: 2014
- Authors: Notayi, Mzwamadoda
- Date: 2014
- Subjects: Animal fibres , Textile fabrics , Animal science
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10552 , http://hdl.handle.net/10948/d1020426
- Description: Identification of fibres, particularly in blends, requires knowledge of their characteristics. Individual Identifying features between wool and mohair fibres were investigated in this study using a Scanning Electron Microscope (SEM), Fourier Transform Infrared-Attenuated Total Reflection (FTIR-ATR), Fourier Transform Raman and Atomic Force Microscope (AFM). This study confirmed that wool and mohair can be differentiated and identified in blends using the cuticle scale height (CSH) criterion, wool having an average CSH of 0.6 ± 0.1 μm and mohair having an average CSH of 0.4 ± 0.1 μm. The AFM provided highly reproducible CSH results, which also confirmed the SEM results that indeed wool and mohair could be differentiated using the CSH as criterion. The AFM gave a CSH value of 0.9 ± 0.2 μm for wool and 0.6 ± 0.2 μm for mohair, the difference between the two results being statistically significant according to the student t-test. It has been demonstrated that wool and mohair identification in blends is possible, by using the AFM to measure CSH, although the method is very time consuming and might be expensive. The FTIR-ATR showed similar spectra for wool and mohair fibres, confirming that the two fibre types consist of the same polymer material. Nevertheless, a difference was observed in the ratios of the relative intensities of the amide I (around 1630 cm-1) to the amide II (around 1515cm-1) absorption bands. The FT Raman provided similar spectra for the wool and mohair fibres, although a possible distinguishing feature between the two fibres could be the intensities of the alkyl side chains chemical band near 2940 cm-1 in the spectra of the two fibre types. According to the results obtained in this study, the FTIR-ATR and the FT Raman techniques may have potential for differentiating between wool and mohair but this requires further investigation.
- Full Text:
- Date Issued: 2014
Characterization of chromatic dispersion in single mode fibre
- Authors: Wassin, Shukree
- Date: 2014
- Subjects: Fiber optics Electromagnetic waves , Electromagnetic waves -- Transmission
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47807 , vital:40379
- Description: In this dissertation, an investigation of chromatic dispersion is presented. The Pulse delay and phase Shift chromatic dispersion characterization techniques were used for conducting the measurements. The experiments were performed in a modern optical fibre research laboratory and chromatic dispersion measurements were carried out on several lengths of G.652 and G.655 single mode fibres. The pulse delay characterization technique measures the time of flight between two modulated optical signals whilst propagating along the fibre under test. During phase shift experiments, the group delay is obtained by measuring the relative phase difference as a function of wavelength, between adjacent sinusoidal light signals. The pulse delay and phase shift characterization techniques illustrated excellent agreement in the measured! chromatic Dispersion coefficients along the G.652 standard single mode! fibre as well as the G.655 positive and negative non-zero dispersion shifted fibre. It was found that the measurement accuracy improved as the fibre length increased. A periodic shift between the modulated optical signals, propagating along the fibre was experimentally observed. It is to be remarked that the longer wavelength signals propagated faster along the G.655 positive non-zero dispersion shifted fibre in comparison to its transmission within the G.655 negative non-zero dispersion shifted fibre. Furthermore, it was found that the sinusoidal signal shifted towards the left along the G.655 negative NZDSF fibre whilst the shift occurred towards the right along the G.655 positive NZDSF fibre. Generally, the shift arising along the G.655 fibres was found to be smaller than the shift seen throughout the G.652 fibres. Towards the end of this study, a chromatic dispersion compensation system was designed and tested. Once characterization of the compensation link was completed, it was experimentally illustrated that the chromatic dispersion across the system was successfully reduced. Finally, a sum of squares of error statistical test showed that the phase shift technique is more accurate in comparison to the pulse delay method. This result was found to be in good agreement with published work found in literature.
- Full Text:
- Date Issued: 2014
- Authors: Wassin, Shukree
- Date: 2014
- Subjects: Fiber optics Electromagnetic waves , Electromagnetic waves -- Transmission
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10948/47807 , vital:40379
- Description: In this dissertation, an investigation of chromatic dispersion is presented. The Pulse delay and phase Shift chromatic dispersion characterization techniques were used for conducting the measurements. The experiments were performed in a modern optical fibre research laboratory and chromatic dispersion measurements were carried out on several lengths of G.652 and G.655 single mode fibres. The pulse delay characterization technique measures the time of flight between two modulated optical signals whilst propagating along the fibre under test. During phase shift experiments, the group delay is obtained by measuring the relative phase difference as a function of wavelength, between adjacent sinusoidal light signals. The pulse delay and phase shift characterization techniques illustrated excellent agreement in the measured! chromatic Dispersion coefficients along the G.652 standard single mode! fibre as well as the G.655 positive and negative non-zero dispersion shifted fibre. It was found that the measurement accuracy improved as the fibre length increased. A periodic shift between the modulated optical signals, propagating along the fibre was experimentally observed. It is to be remarked that the longer wavelength signals propagated faster along the G.655 positive non-zero dispersion shifted fibre in comparison to its transmission within the G.655 negative non-zero dispersion shifted fibre. Furthermore, it was found that the sinusoidal signal shifted towards the left along the G.655 negative NZDSF fibre whilst the shift occurred towards the right along the G.655 positive NZDSF fibre. Generally, the shift arising along the G.655 fibres was found to be smaller than the shift seen throughout the G.652 fibres. Towards the end of this study, a chromatic dispersion compensation system was designed and tested. Once characterization of the compensation link was completed, it was experimentally illustrated that the chromatic dispersion across the system was successfully reduced. Finally, a sum of squares of error statistical test showed that the phase shift technique is more accurate in comparison to the pulse delay method. This result was found to be in good agreement with published work found in literature.
- Full Text:
- Date Issued: 2014
Comparison of the population growth potential of South African loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles
- Authors: Tucek, Jenny Bianka
- Date: 2014
- Subjects: Sea turtles -- Population viability analysis -- South Africa , Migratory animals -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/5032 , vital:20793
- Description: A beach conservation programme protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles in South Africa was started in 1963. As initial numbers of nesting females were low for both species (107 loggerheads and 24 leatherbacks) it was proposed that the protection of eggs, hatchlings and nesting females along the nesting beach would induce population growth and prohibit local extinction. Today, 50 years later, the loggerhead population exceeds 650 females per annum, whereas the leatherback population counts about 65 nesting females per year. The trend for leatherback turtles is that the population has been stable for about 30 years whereas loggerheads are increasing exponentially. Thus, this thesis investigated several life-history traits to explain the differing responses to the ongoing beach conservation programme. Reproductive output and success were assessed for both species; it was hypothesised that environmental conditions are sub-optimal for leatherback turtles to reproduce successfully. It was ascertained that nesting loggerhead females deposit larger clutches than leatherbacks (112 ± SD 20 eggs and 100 ± SD 23 eggs, respectively), but that annual reproductive output per individual leatherback female exceeds that of loggerhead turtles (±700 eggs and ±448 eggs, respectively) because they exhibit a higher intra-seasonal nesting frequency (leatherbacks n = 7 and loggerheads n = 4 from Nel et al. 2013). Emergence success (i.e. the percentage of hatchlings produced) per nest was similar for both species (loggerhead 73.6 ± SD 27.68 % and leatherback turtles 73.8 ± SD 22.70 %), but as loggerhead turtles nest in greater numbers, i.e. producing more hatchlings per year, the absolute population growth potential favours the loggerhead turtle. The second factor investigated was sex ratio because sea turtles display temperature-dependent sex determination (TSD) where extreme incubation temperatures can skew the sex ratio (i.e. feminising or masculinising a clutch). It was suspected that leatherback turtles are male-biased as this is the southern-most rookery (for both species). Further, leatherback nests are generally closer to the high tide mark, which might induce a cooling effect. Standard histological techniques were applied to sex hatchlings and a generalized linear model (GLM) was used to approximate annual sex ratio. Loggerhead sex ratio (2009 - 2011) was estimated at 86.9 ± SE 0.35 % female-biased; however, sufficient replication for the leatherback population was only obtained for season 2010, which indicated a 97.1 % (95 % CI 93.3 - 98.7) female bias. Both species are, thus, highly female-biased, and current sex ratio for leatherback turtles is not prohibiting population growth. Current sex ratios, however, are not necessarily indicative of sex ratios in the past which would have induced present population growth. Thus, to account for present population growth profiles, sex ratios from the past needed to be ascertained. Annual sex ratios (1997 - 2011) were modelled from historical air and sea surface temperatures (SSTs) but no significant change over time was obtained for either loggerhead or leatherback turtles (linear regression; p ≥ 0.45). The average sex ratio over this 15-year period for the South African loggerhead turtle was approximated at 77.1 ± SE 3.36 % female-biased, whereas leatherbacks exhibited a 99.5 ± SE 0.24 % female bias. Re-analysing data from the mid-80s by Maxwell et al. (1988) also indicated a 77.4 % female bias for the South African loggerhead population. It is, therefore, highly likely that sex ratios of the South African loggerhead and leatherback sea turtle populations have been stable for at least three decades and are not accountable for the differing population growth profiles as they are displayed today. Another possibility that could explain the opposed population growth profiles is the time taken for animals to replace themselves, i.e. age at maturity. It was suspected that age at maturity for the South African loggerhead turtle is comparable with that for leatherbacks. Using data from a 30-year mutilation tagging experiment (i.e. notching), age at first reproduction for South African loggerhead females was estimated. Results ranged broadly but a mean of 36.2 ± SD 7.71 years was obtained using a Gaussian distribution. Age at reproduction of the South African leatherback turtle was not determined but the literature suggests a much younger age of 13.3 - 26.8 years (Zug & Parham 1996, Dutton et al. 2005, Avens et al. 2009, Jones et al. 2011). Therefore, population growth would favour leatherback turtles as they exhibit a much shorter generation time. Finally, it was concluded that all life-history parameters investigated favour leatherback turtles, yet loggerheads are displaying population growth. However, as there were no obvious constraints to population growth on the nesting beach, it is suspected that population growth of the South African leatherback turtle is either unobserved (due to inadequate monitoring not capturing sufficient numbers of nesting events to establish a trend) or that population growth is prohibited by some offshore factor such as industrial fisheries (or some other driver not yet identified). Monitoring should, thus, be expanded and offshore mortality monitored as the leatherback population nesting in South Africa is still critically endangered with nesting numbers dangerously low.
- Full Text:
- Date Issued: 2014
- Authors: Tucek, Jenny Bianka
- Date: 2014
- Subjects: Sea turtles -- Population viability analysis -- South Africa , Migratory animals -- South Africa
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10948/5032 , vital:20793
- Description: A beach conservation programme protecting nesting loggerhead (Caretta caretta) and leatherback (Dermochelys coriacea) sea turtles in South Africa was started in 1963. As initial numbers of nesting females were low for both species (107 loggerheads and 24 leatherbacks) it was proposed that the protection of eggs, hatchlings and nesting females along the nesting beach would induce population growth and prohibit local extinction. Today, 50 years later, the loggerhead population exceeds 650 females per annum, whereas the leatherback population counts about 65 nesting females per year. The trend for leatherback turtles is that the population has been stable for about 30 years whereas loggerheads are increasing exponentially. Thus, this thesis investigated several life-history traits to explain the differing responses to the ongoing beach conservation programme. Reproductive output and success were assessed for both species; it was hypothesised that environmental conditions are sub-optimal for leatherback turtles to reproduce successfully. It was ascertained that nesting loggerhead females deposit larger clutches than leatherbacks (112 ± SD 20 eggs and 100 ± SD 23 eggs, respectively), but that annual reproductive output per individual leatherback female exceeds that of loggerhead turtles (±700 eggs and ±448 eggs, respectively) because they exhibit a higher intra-seasonal nesting frequency (leatherbacks n = 7 and loggerheads n = 4 from Nel et al. 2013). Emergence success (i.e. the percentage of hatchlings produced) per nest was similar for both species (loggerhead 73.6 ± SD 27.68 % and leatherback turtles 73.8 ± SD 22.70 %), but as loggerhead turtles nest in greater numbers, i.e. producing more hatchlings per year, the absolute population growth potential favours the loggerhead turtle. The second factor investigated was sex ratio because sea turtles display temperature-dependent sex determination (TSD) where extreme incubation temperatures can skew the sex ratio (i.e. feminising or masculinising a clutch). It was suspected that leatherback turtles are male-biased as this is the southern-most rookery (for both species). Further, leatherback nests are generally closer to the high tide mark, which might induce a cooling effect. Standard histological techniques were applied to sex hatchlings and a generalized linear model (GLM) was used to approximate annual sex ratio. Loggerhead sex ratio (2009 - 2011) was estimated at 86.9 ± SE 0.35 % female-biased; however, sufficient replication for the leatherback population was only obtained for season 2010, which indicated a 97.1 % (95 % CI 93.3 - 98.7) female bias. Both species are, thus, highly female-biased, and current sex ratio for leatherback turtles is not prohibiting population growth. Current sex ratios, however, are not necessarily indicative of sex ratios in the past which would have induced present population growth. Thus, to account for present population growth profiles, sex ratios from the past needed to be ascertained. Annual sex ratios (1997 - 2011) were modelled from historical air and sea surface temperatures (SSTs) but no significant change over time was obtained for either loggerhead or leatherback turtles (linear regression; p ≥ 0.45). The average sex ratio over this 15-year period for the South African loggerhead turtle was approximated at 77.1 ± SE 3.36 % female-biased, whereas leatherbacks exhibited a 99.5 ± SE 0.24 % female bias. Re-analysing data from the mid-80s by Maxwell et al. (1988) also indicated a 77.4 % female bias for the South African loggerhead population. It is, therefore, highly likely that sex ratios of the South African loggerhead and leatherback sea turtle populations have been stable for at least three decades and are not accountable for the differing population growth profiles as they are displayed today. Another possibility that could explain the opposed population growth profiles is the time taken for animals to replace themselves, i.e. age at maturity. It was suspected that age at maturity for the South African loggerhead turtle is comparable with that for leatherbacks. Using data from a 30-year mutilation tagging experiment (i.e. notching), age at first reproduction for South African loggerhead females was estimated. Results ranged broadly but a mean of 36.2 ± SD 7.71 years was obtained using a Gaussian distribution. Age at reproduction of the South African leatherback turtle was not determined but the literature suggests a much younger age of 13.3 - 26.8 years (Zug & Parham 1996, Dutton et al. 2005, Avens et al. 2009, Jones et al. 2011). Therefore, population growth would favour leatherback turtles as they exhibit a much shorter generation time. Finally, it was concluded that all life-history parameters investigated favour leatherback turtles, yet loggerheads are displaying population growth. However, as there were no obvious constraints to population growth on the nesting beach, it is suspected that population growth of the South African leatherback turtle is either unobserved (due to inadequate monitoring not capturing sufficient numbers of nesting events to establish a trend) or that population growth is prohibited by some offshore factor such as industrial fisheries (or some other driver not yet identified). Monitoring should, thus, be expanded and offshore mortality monitored as the leatherback population nesting in South Africa is still critically endangered with nesting numbers dangerously low.
- Full Text:
- Date Issued: 2014
Contemporary use and seasonal abundance of indigenous edible plants (with an emphasis on geophytes) available to human foragers on the Cape south coast, South Africa
- Authors: De Vynck, Jan Carlo
- Date: 2014
- Subjects: Wild plants, Edible -- Africa, Southern , Coastal plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10638 , http://hdl.handle.net/10948/d1020044
- Description: Human subsistence within the Cape Floristic Region (Cape) dates back to our inception as a distinct species. Unique archaeological evidence found here for the defining attribute of cognitive modernity, as well as coinciding paleo-climatic challenges to survival, both highlight the Cape’s potential to support the existence of pre-historic hunter-gatherers. This habitat, with its unprecedented diversity of geophytes and other plant growth forms, has not yet revealed its potential to provide carbohydrate resources for early Homo sapiens sapiens. In order to investigate this potential, an ethnobotanical survey of the south Cape coastal area near Still Bay was conducted. Despite 17th Century colonialism marking the onset of indigenous plant knowledge decline, the 18 people of Khoe-San descent interviewed in this survey still actively used 58 indigenous edible plant species with a variety of 69 uses. Fruit showed the highest popularity of plants used (52 percent) followed by nectar, with plants having underground storage organs (USOs) ranking third (34 percent). Among growth forms, shrubs dominated (34 percent) followed by geophytes and trees (both 21 percent). With the exception of Prionium serratum, which was rare in the research area, this study failed to identify species that could have formed a staple source of carbohydrate for pre-colonial Khoe-San peoples of the Cape south coast. While eight species of USOs were identified (12 percent of total) only Cyphia species emerged as an important carbohydrate source. This study indicated the importance of Thicket Biome species as a source of edible plants. The second component of the study comprised a two year phenological survey of indigenous edible plant species in four primary vegetation types. A total of 32 USO species and 21 species with aboveground edible carbohydrates (fruiting species) were identified across all sites. Limestone Fynbos had the richest flora of edible species (21 USO species and 18 fruiting species), followed by Strandveld (15 USOs and 13 fruiting species), Renosterveld (8 and 8, respectively) and lastly Sand Fynbos (5 and 5, respectively). The season of highest apparency showed slight variation amongst the four sites over the two years, with more variation evident in the period of apparency. The first survey year had below average rainfall, while the second year received an average rainfall amount. The second year saw a dramatic increase in apparency of abundance for all sites (50 to 60 percent increase) except for the Sand Fynbos site, which showed little change. The other sites showed a one month increase in the period of apparency in the second survey year. Overall, late summer to autumn was the period of lowest apparency of USOs. The ripening of certain fruiting species during this time would have provided a source of carbohydrate when USO availability was at its lowest. Strandveld had the highest biomass in the peak of apparency (over 80 kgha-1) in the first year with a nearly 20 percent increase for the second year. The combined biomass for the four study sites in the first survey year was roughly 150 kgha-1 and 185 kgha-1 for the second year. The apparency of abundance (ripe and edible phase) of fruiting species did not increase much for Renosterveld and Strandveld in the second survey year, except for Limestone Fynbos (49 percent increase) and Sand Fynbos (53 percent). A multivariate analysis showed seven phenophases for high apparency of edible USOs and ripe fruit across the four vegetation types. Given the contribution of evergreen USOs and fruiting species, there would always have been carbohydrates available for foragers to collect in the major vegetation types of the south Cape coast. However, harvesting and processing this carbohydrate resource would have posed cognitive challenges for MSA hunter-gatherers, given the interwoven taxonomic complexity of numerous toxic plant species, and the diverse phenology of edible plant species within the varied vegetation types. These challenges were undoubtedly mastered, highlighting the Cape environment as a possible catalyst to improved human cognitive maturity.
- Full Text:
- Date Issued: 2014
- Authors: De Vynck, Jan Carlo
- Date: 2014
- Subjects: Wild plants, Edible -- Africa, Southern , Coastal plants -- South Africa
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:10638 , http://hdl.handle.net/10948/d1020044
- Description: Human subsistence within the Cape Floristic Region (Cape) dates back to our inception as a distinct species. Unique archaeological evidence found here for the defining attribute of cognitive modernity, as well as coinciding paleo-climatic challenges to survival, both highlight the Cape’s potential to support the existence of pre-historic hunter-gatherers. This habitat, with its unprecedented diversity of geophytes and other plant growth forms, has not yet revealed its potential to provide carbohydrate resources for early Homo sapiens sapiens. In order to investigate this potential, an ethnobotanical survey of the south Cape coastal area near Still Bay was conducted. Despite 17th Century colonialism marking the onset of indigenous plant knowledge decline, the 18 people of Khoe-San descent interviewed in this survey still actively used 58 indigenous edible plant species with a variety of 69 uses. Fruit showed the highest popularity of plants used (52 percent) followed by nectar, with plants having underground storage organs (USOs) ranking third (34 percent). Among growth forms, shrubs dominated (34 percent) followed by geophytes and trees (both 21 percent). With the exception of Prionium serratum, which was rare in the research area, this study failed to identify species that could have formed a staple source of carbohydrate for pre-colonial Khoe-San peoples of the Cape south coast. While eight species of USOs were identified (12 percent of total) only Cyphia species emerged as an important carbohydrate source. This study indicated the importance of Thicket Biome species as a source of edible plants. The second component of the study comprised a two year phenological survey of indigenous edible plant species in four primary vegetation types. A total of 32 USO species and 21 species with aboveground edible carbohydrates (fruiting species) were identified across all sites. Limestone Fynbos had the richest flora of edible species (21 USO species and 18 fruiting species), followed by Strandveld (15 USOs and 13 fruiting species), Renosterveld (8 and 8, respectively) and lastly Sand Fynbos (5 and 5, respectively). The season of highest apparency showed slight variation amongst the four sites over the two years, with more variation evident in the period of apparency. The first survey year had below average rainfall, while the second year received an average rainfall amount. The second year saw a dramatic increase in apparency of abundance for all sites (50 to 60 percent increase) except for the Sand Fynbos site, which showed little change. The other sites showed a one month increase in the period of apparency in the second survey year. Overall, late summer to autumn was the period of lowest apparency of USOs. The ripening of certain fruiting species during this time would have provided a source of carbohydrate when USO availability was at its lowest. Strandveld had the highest biomass in the peak of apparency (over 80 kgha-1) in the first year with a nearly 20 percent increase for the second year. The combined biomass for the four study sites in the first survey year was roughly 150 kgha-1 and 185 kgha-1 for the second year. The apparency of abundance (ripe and edible phase) of fruiting species did not increase much for Renosterveld and Strandveld in the second survey year, except for Limestone Fynbos (49 percent increase) and Sand Fynbos (53 percent). A multivariate analysis showed seven phenophases for high apparency of edible USOs and ripe fruit across the four vegetation types. Given the contribution of evergreen USOs and fruiting species, there would always have been carbohydrates available for foragers to collect in the major vegetation types of the south Cape coast. However, harvesting and processing this carbohydrate resource would have posed cognitive challenges for MSA hunter-gatherers, given the interwoven taxonomic complexity of numerous toxic plant species, and the diverse phenology of edible plant species within the varied vegetation types. These challenges were undoubtedly mastered, highlighting the Cape environment as a possible catalyst to improved human cognitive maturity.
- Full Text:
- Date Issued: 2014