A case study : exploring a DVD driven approach for teaching and learning mathematics, at secondary school level, with a framework of blended learning
- Authors: Padayachee, Pragashni
- Date: 2010
- Subjects: Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10504 , http://hdl.handle.net/10948/1384 , Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Description: Post-apartheid South Africa is witnessing an education crisis of significant proportions. The new outcomes-based education system has failed to deliver and universities are suffering the consequences of under-preparation of learners for tertiary studies especially in mathematics. The educator corps is lacking and it has become common practice for universities to deploy augmented programmes in mathematics for secondary school learners in the surrounding areas. This thesis describes a particular approach of blended learning, devised for the Incubator School Project (ISP), an initiative of the Nelson Mandela Metropolitan University (NMMU) in the Eastern Cape of South Africa. The defining feature of this blended approach is that it incorporates DVD technology, which offers an affordable and accessible option for the particular group of learners and the schools they attend. The thesis poses the research question: How did the use of the DVD approach within a blended learning environment support the learning of mathematics? This case study explores the particular blended approach and reports six fold on the approach – qualitatively based firstly on a questionnaire completed by learners and secondly on interviews of learners, thirdly on the facilitators reports, fourthly quantitatively on learner performance before and after the intervention. Fifthly six schools are used as a case study where the mathematics performance of the learners who participated in the ISP is compared to those who did not participate in the ISP. Finally the scope of blending of this model is evaluated by means of a radar chart, adapted from an existing radar measure. This research revealed that using the DVD approach within a blended learning environment did lead to an improvement in learners perceptions about mathematics, an improvement in the manner in which they learned mathematics, an extension in their mathematics knowledge and provided learners with a supportive environment in which to learn mathematics. The elements which supported learning in this approach are presented. The findings of the study suggest that this approach impacted favourably on the mathematics learning and enhanced the mathematics learning and performance of these learners. Recommendations are offered for practice, teachers and schools and for further research possibilities.
- Full Text:
- Date Issued: 2010
- Authors: Padayachee, Pragashni
- Date: 2010
- Subjects: Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10504 , http://hdl.handle.net/10948/1384 , Matehmatics -- Study and Teaching (Secondary) -- Audio-visual aids , Matehmatics -- Study and Teaching (Secondary) -- South Africa -- Port Elizabeth
- Description: Post-apartheid South Africa is witnessing an education crisis of significant proportions. The new outcomes-based education system has failed to deliver and universities are suffering the consequences of under-preparation of learners for tertiary studies especially in mathematics. The educator corps is lacking and it has become common practice for universities to deploy augmented programmes in mathematics for secondary school learners in the surrounding areas. This thesis describes a particular approach of blended learning, devised for the Incubator School Project (ISP), an initiative of the Nelson Mandela Metropolitan University (NMMU) in the Eastern Cape of South Africa. The defining feature of this blended approach is that it incorporates DVD technology, which offers an affordable and accessible option for the particular group of learners and the schools they attend. The thesis poses the research question: How did the use of the DVD approach within a blended learning environment support the learning of mathematics? This case study explores the particular blended approach and reports six fold on the approach – qualitatively based firstly on a questionnaire completed by learners and secondly on interviews of learners, thirdly on the facilitators reports, fourthly quantitatively on learner performance before and after the intervention. Fifthly six schools are used as a case study where the mathematics performance of the learners who participated in the ISP is compared to those who did not participate in the ISP. Finally the scope of blending of this model is evaluated by means of a radar chart, adapted from an existing radar measure. This research revealed that using the DVD approach within a blended learning environment did lead to an improvement in learners perceptions about mathematics, an improvement in the manner in which they learned mathematics, an extension in their mathematics knowledge and provided learners with a supportive environment in which to learn mathematics. The elements which supported learning in this approach are presented. The findings of the study suggest that this approach impacted favourably on the mathematics learning and enhanced the mathematics learning and performance of these learners. Recommendations are offered for practice, teachers and schools and for further research possibilities.
- Full Text:
- Date Issued: 2010
A combination of platinum anticancer drugs and mangiferin causes increased efficacy in cancer cell lines
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
- Authors: Du Plessis-Stoman, Debbie
- Date: 2010
- Subjects: Cancer -- Chemotherapy , Antineoplastic agents , Platinum compounds -- Therapeutic use , Cancer cells
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10338 , http://hdl.handle.net/10948/d1016160
- Description: This thesis mainly deals with some biochemical aspects regarding the efficacy of novel platinum anticancer compounds alone and in combination with mangiferin, as part of a broader study in which both chemistry and biochemistry are involved. Various novel diamine and N-S donor chelate compounds of platinum II and IV have been developed in which factors such as stereochemistry, ligand exchange rate and biocompatibility were considered as additional parameters. In the first order testing, each of these compounds was tested with reference to their “killing” potential by comparing their rate of killing, over a period of 48 hours with those of cisplatin and oxaliplatin. Numerous novel compounds were tested in this way, using the MTT cell viability assay and the three cancer cell lines MCF7, HT29 and HeLa. Although only a few could be regarded as equal to or even better than cisplatin, CPA7 and oxaliplatin, the testing of these compounds on cancer cells provided useful knowledge for the further development of novel compounds. Three of the better compounds, namely Yol 25, Yol 29.1 and Mar 4.1.4 were selected for further studies, together with oxaliplatin and CPA7 as positive controls, to obtain more detailed knowledge of their anticancer action, both alone and when applied in combination with mangiferin. In addition to the above, resistant cells were produced for each of the three different cell lines tested and all the selected compounds, both in the presence and absence of mangiferin. The effects of these treatments on the activation of NFĸB when applied to normal and resistant cell lines were also investigated. All the compounds induced apoptosis in the cell lines tested as well as alter the DNA cycle at one or more phase. Additionally, combination of these compounds with mangiferin enhanced the above-mentioned effects. Mangiferin decreases the IC50 values of the platinum drugs by up to 3.4 times and, although mangiferin alone did not induce cell cycle arrest, the presence of mangiferin in combination with oxaliplatin and Yol 25 shows an earlier and greatly enhanced delay in the S-phase, while cells treated with CPA7, Yol 29.1 and Mar 4.1.4 in combination with mangiferin showed a later, but greatly enhanced delay in the S-phase. It was also found that mangiferin acts as an NFĸB inhibitor when applied in combination with these drugs, which, in turn, reduces the occurrence of resistance in the cell lines. Resistance to oxaliplatin was counteracted by the combination with mangiferin in HeLa and HT29, but not in MCF7 cells, while resistance to CPA7 was only counteracted in the MCF7 cell line. Yol 25 and Mar 4.1.4 did not seem to induce resistance in HeLa and MCF7 cells, but did in HT29 cells, whereas Yol 29.1 caused resistance in HeLa and HT29 cells, but not in MCF7 cells. Finally, an effort was made to evaluate the different compounds by comparing them with respect to their properties relating to anticancer action with and without the addition of mangiferin.
- Full Text:
- Date Issued: 2010
A comparative study of artificial neural networks and physics models as simulators in evolutionary robotics
- Pretorius, Christiaan Johannes
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
- Authors: Pretorius, Christiaan Johannes
- Date: 2019
- Subjects: Neural networks (Computer science)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30789 , vital:31131
- Description: The Evolutionary Robotics (ER) process is a technique that applies evolutionary optimization algorithms to the task of automatically developing, or evolving, robotic control programs. These control programs, or simply controllers, are evolved in order to allow a robot to perform a required task. During the ER process, use is often made of robotic simulators to evaluate the performance of candidate controllers that are produced in the course of the controller evolution process. Such simulators accelerate and otherwise simplify the controller evolution process, as opposed to the more arduous process of evaluating controllers in the real world without use of simulation. To date, the vast majority of simulators that have been applied in ER are physics- based models which are constructed by taking into account the underlying physics governing the operation of the robotic system in question. An alternative approach to simulator implementation in ER is the usage of Artificial Neural Networks (ANNs) as simulators in the ER process. Such simulators are referred to as Simulator Neural Networks (SNNs). Previous studies have indicated that SNNs can successfully be used as an alter- native to physics-based simulators in the ER process on various robotic platforms. At the commencement of the current study it was not, however, known how this relatively new method of simulation would compare to traditional physics-based simulation approaches in ER. The study presented in this thesis thus endeavoured to quantitatively compare SNNs and physics-based models as simulators in the ER process. In order to con- duct this comparative study, both SNNs and physics simulators were constructed for the modelling of three different robotic platforms: a differentially-steered robot, a wheeled inverted pendulum robot and a hexapod robot. Each of these two types of simulation was then used in simulation-based evolution processes to evolve con- trollers for each robotic platform. During these controller evolution processes, the SNNs and physics models were compared in terms of their accuracy in making pre- dictions of robotic behaviour, their computational efficiency in arriving at these predictions, the human effort required to construct each simulator and, most im- portantly, the real-world performance of controllers evolved by making use of each simulator. The results obtained in this study illustrated experimentally that SNNs were, in the majority of cases, able to make more accurate predictions than the physics- based models and these SNNs were arguably simpler to construct than the physics simulators. Additionally, SNNs were also shown to be a computationally efficient alternative to physics-based simulators in ER and, again in the majority of cases, these SNNs were able to produce controllers which outperformed those evolved in the physics-based simulators, when these controllers were uploaded to the real-world robots. The results of this thesis thus suggest that SNNs are a viable alternative to more commonly-used physics simulators in ER and further investigation of the potential of this simulation technique appears warranted.
- Full Text:
- Date Issued: 2019
A comparison of programming notations for a tertiary level introductory programming course
- Authors: Cilliers, Charmain Barbara
- Date: 2004
- Subjects: Computer programming -- Study and teaching (Higher) -- South Africa , Computer programmers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11093 , http://hdl.handle.net/10948/d1019679
- Description: Increasing pressure from national government to improve throughput at South African tertiary education institutions presents challenges to educators of introductory programming courses. In response, educators must adopt effective methods and strategies that encourage novice programmers to be successful in such courses. An approach that seeks to increase and maintain satisfactory throughput is the modification of the teaching model in these courses by adjusting presentation techniques. This thesis investigates the effect of integrating an experimental iconic programming notation and associated development environment with existing conventional textual technological support in the teaching model of a tertiary level introductory programming course. The investigation compares the performance achievement of novice programmers using only conventional textual technological support with that of novice programmers using the integrated iconic and conventional textual technological support. In preparation for the investigation, interpretation of existing knowledge on the behaviour of novice programmers while learning to program results in a novel framework of eight novice programmer requirements for technological support in an introductory programming course. This framework is applied in the examination of existing categories of technological support as well as in the design of new technological support for novice programmers learning to program. It thus provides information for the selection of existing and the design of new introductory programming technological support. The findings of the investigation suggest strong evidence that performance achievement of novice programmers in a tertiary level introductory programming course improves significantly with the inclusion of iconic technological support in the teaching model. The benefits are particularly evident in the portion of the novice programmer population who have been identified as being at risk of being successful in the course. Novice programmers identified as being at risk perform substantially better when using iconic technological support concurrently with conventional textual technological support than their equals who use only the latter form. Considerably more at risk novice programmers using the integrated form of technological support are in fact successful in the introductory programming course when compared with their counterparts who use conventional textual technological support only. The contributions of this thesis address deficiencies existing in current documented research. These contributions are primarily apparent in a number of distinct areas, namely: • formalisation of a novel framework of novice programmer requirements for technological support in an introductory programming course; • application of the framework as a formal evaluation technique; • application of the framework in the design of a visual iconic programming notation and development environment; • enhancement of existing empirical evidence and experimental research methodology typically applied to studies in programming; as well as • a proposal for a modified introductory programming course teaching model. The thesis has effectively applied substantial existing research on the cognitive model of the novice programmer as well as that on experimental technological support. The increase of throughput to a recommended rate of 75 percent in the tertiary level introductory programming course at the University of Port Elizabeth is attributed solely to the incorporation of iconic technological support in the teaching model of the course.
- Full Text:
- Date Issued: 2004
- Authors: Cilliers, Charmain Barbara
- Date: 2004
- Subjects: Computer programming -- Study and teaching (Higher) -- South Africa , Computer programmers -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:11093 , http://hdl.handle.net/10948/d1019679
- Description: Increasing pressure from national government to improve throughput at South African tertiary education institutions presents challenges to educators of introductory programming courses. In response, educators must adopt effective methods and strategies that encourage novice programmers to be successful in such courses. An approach that seeks to increase and maintain satisfactory throughput is the modification of the teaching model in these courses by adjusting presentation techniques. This thesis investigates the effect of integrating an experimental iconic programming notation and associated development environment with existing conventional textual technological support in the teaching model of a tertiary level introductory programming course. The investigation compares the performance achievement of novice programmers using only conventional textual technological support with that of novice programmers using the integrated iconic and conventional textual technological support. In preparation for the investigation, interpretation of existing knowledge on the behaviour of novice programmers while learning to program results in a novel framework of eight novice programmer requirements for technological support in an introductory programming course. This framework is applied in the examination of existing categories of technological support as well as in the design of new technological support for novice programmers learning to program. It thus provides information for the selection of existing and the design of new introductory programming technological support. The findings of the investigation suggest strong evidence that performance achievement of novice programmers in a tertiary level introductory programming course improves significantly with the inclusion of iconic technological support in the teaching model. The benefits are particularly evident in the portion of the novice programmer population who have been identified as being at risk of being successful in the course. Novice programmers identified as being at risk perform substantially better when using iconic technological support concurrently with conventional textual technological support than their equals who use only the latter form. Considerably more at risk novice programmers using the integrated form of technological support are in fact successful in the introductory programming course when compared with their counterparts who use conventional textual technological support only. The contributions of this thesis address deficiencies existing in current documented research. These contributions are primarily apparent in a number of distinct areas, namely: • formalisation of a novel framework of novice programmer requirements for technological support in an introductory programming course; • application of the framework as a formal evaluation technique; • application of the framework in the design of a visual iconic programming notation and development environment; • enhancement of existing empirical evidence and experimental research methodology typically applied to studies in programming; as well as • a proposal for a modified introductory programming course teaching model. The thesis has effectively applied substantial existing research on the cognitive model of the novice programmer as well as that on experimental technological support. The increase of throughput to a recommended rate of 75 percent in the tertiary level introductory programming course at the University of Port Elizabeth is attributed solely to the incorporation of iconic technological support in the teaching model of the course.
- Full Text:
- Date Issued: 2004
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 contribution to the theory of prime modules
- Authors: Ssevviiri, David
- Date: 2013
- Subjects: Modules (Algebra) , Radical theory , Rings (Algebra)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10510 , http://hdl.handle.net/10948/d1019923
- Description: This thesis is aimed at generalizing notions of rings to modules. In par-ticular, notions of completely prime ideals, s-prime ideals, 2-primal rings and nilpotency of elements of rings are respectively generalized to completely prime submodules and classical completely prime submodules, s-prime submodules, 2-primal modules and nilpotency of elements of modules. Properties and rad-icals that arise from each of these notions are studied.
- Full Text:
- Date Issued: 2013
- Authors: Ssevviiri, David
- Date: 2013
- Subjects: Modules (Algebra) , Radical theory , Rings (Algebra)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10510 , http://hdl.handle.net/10948/d1019923
- Description: This thesis is aimed at generalizing notions of rings to modules. In par-ticular, notions of completely prime ideals, s-prime ideals, 2-primal rings and nilpotency of elements of rings are respectively generalized to completely prime submodules and classical completely prime submodules, s-prime submodules, 2-primal modules and nilpotency of elements of modules. Properties and rad-icals that arise from each of these notions are studied.
- Full Text:
- Date Issued: 2013
A framework for designing ambient assisted living services for disabled individuals
- Authors: Kyazze, Michael
- Date: 2018
- Subjects: Assistive computer technology , Computers and people with disabilities Self-help devices for people with disabilities People with disabilities -- Means of communication -- Technological innovations Communication devices for people with disabilities
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/31240 , vital:31347
- Description: Physically disabled individuals face a number of challenges when carrying out their everyday activities such as moving around, communicating with others, and their personal care. One way of overcoming these challenges is by using personal assistants. An alternative is to enable independence through assistive technology. This research aimed to investigate how physically disabled individuals experience these challenges, and how assistive technology can enable them to be more independent. In order to achieve the goal of this research, existing literature was reviewed on disability, assisted living, and interaction techniques. The literature study on disability identified some of the challenges faced by disabled individuals in their daily lives. In order to contextualize these challenges, interview studies with eighteen disabled individuals, and twelve personal assistants were carried out in Kampala, Uganda and Port Elizabeth, South Africa. The participants from both Uganda and South Africa were limited to those living in urban areas. The Ugandan participants noted that, whereas technology may assist their daily lives, their most essential needs are basic disability support aids such as wheelchairs and better long canes. This was in contrast with the South African participants, who have access to basic disability support aids. The South African participants identified their key needs as controlling an electronic environment without assistance, e.g. house lights, using a mobile phone, and using a computer without assistance. The interviews narrowed down the scope to focus on individuals with quadriplegia, specifically individuals who have limited hand use, but can comfortably speak and move their heads, and make gestures such as head shake and nod. Literature on assisted living technologies and frameworks, provided the technical foundation for the research. The literature review of interaction techniques identified a number of possible ways in which individuals with quadriplegia can interact with technology. An appropriate set of interaction techniques, namely head shake and nod, voice, and facial feature tracking were identified. Evaluations of the interaction techniques excluded head shake and nod, because of an inconsistency in detecting an individual’s head pose in different lighting conditions, when using a Microsoft Kinect. Voice and facial feature tracking using a standard computer camera were identified as the most suitable interaction techniques for this study. A framework for designing assisted living software services was developed. The framework allows disability researchers and solution developers to understand the needs of a given disability group, and design relevant solutions. To demonstrate that the proposed framework iii | P a g e addresses the main aim of this research, a prototype was developed that enables users to control smart lights (Phillips hue), a Smart TV (Samsung), and carry out basic navigation and webbrowsing on a computer. Users could interact with the software using voice and facial feature commands. A usability study was carried out with fifteen physically disabled individuals in Port Elizabeth, South Africa. The results of the evaluation study were highly positive. The successful evaluation of the prototype provided empirical evidence that the proposed framework does assist in the design of relevant and useful software services, to meet the unique needs of physically disabled individuals.
- Full Text:
- Date Issued: 2018
- Authors: Kyazze, Michael
- Date: 2018
- Subjects: Assistive computer technology , Computers and people with disabilities Self-help devices for people with disabilities People with disabilities -- Means of communication -- Technological innovations Communication devices for people with disabilities
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/31240 , vital:31347
- Description: Physically disabled individuals face a number of challenges when carrying out their everyday activities such as moving around, communicating with others, and their personal care. One way of overcoming these challenges is by using personal assistants. An alternative is to enable independence through assistive technology. This research aimed to investigate how physically disabled individuals experience these challenges, and how assistive technology can enable them to be more independent. In order to achieve the goal of this research, existing literature was reviewed on disability, assisted living, and interaction techniques. The literature study on disability identified some of the challenges faced by disabled individuals in their daily lives. In order to contextualize these challenges, interview studies with eighteen disabled individuals, and twelve personal assistants were carried out in Kampala, Uganda and Port Elizabeth, South Africa. The participants from both Uganda and South Africa were limited to those living in urban areas. The Ugandan participants noted that, whereas technology may assist their daily lives, their most essential needs are basic disability support aids such as wheelchairs and better long canes. This was in contrast with the South African participants, who have access to basic disability support aids. The South African participants identified their key needs as controlling an electronic environment without assistance, e.g. house lights, using a mobile phone, and using a computer without assistance. The interviews narrowed down the scope to focus on individuals with quadriplegia, specifically individuals who have limited hand use, but can comfortably speak and move their heads, and make gestures such as head shake and nod. Literature on assisted living technologies and frameworks, provided the technical foundation for the research. The literature review of interaction techniques identified a number of possible ways in which individuals with quadriplegia can interact with technology. An appropriate set of interaction techniques, namely head shake and nod, voice, and facial feature tracking were identified. Evaluations of the interaction techniques excluded head shake and nod, because of an inconsistency in detecting an individual’s head pose in different lighting conditions, when using a Microsoft Kinect. Voice and facial feature tracking using a standard computer camera were identified as the most suitable interaction techniques for this study. A framework for designing assisted living software services was developed. The framework allows disability researchers and solution developers to understand the needs of a given disability group, and design relevant solutions. To demonstrate that the proposed framework iii | P a g e addresses the main aim of this research, a prototype was developed that enables users to control smart lights (Phillips hue), a Smart TV (Samsung), and carry out basic navigation and webbrowsing on a computer. Users could interact with the software using voice and facial feature commands. A usability study was carried out with fifteen physically disabled individuals in Port Elizabeth, South Africa. The results of the evaluation study were highly positive. The successful evaluation of the prototype provided empirical evidence that the proposed framework does assist in the design of relevant and useful software services, to meet the unique needs of physically disabled individuals.
- Full Text:
- Date Issued: 2018
A framework for grain commodity trading decision support in South Africa
- Authors: Ayankoya, Kayode Anthony
- Date: 2016
- Subjects: Grain trade -- South Africa Commodity exchanges -- South Africa Food industry and trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11437 , vital:26925
- Description: In several countries around the world, grain commodities are traded as assets on stock exchanges. This indicate that the market and effectively the prices of the grain commodities in such countries, are controlled by several local and international economic, political and social factors that are rapidly changing. As a result, the prices of some grain commodities are volatile and trading in such commodities are prone to price-related risks. There are different trading strategies for minimising price-related risks and maximising profits. But empirical research suggests that making the right decision for effective grain commodities trading has been a difficult task for stakeholders due to high volatility of grain commodities prices. Studies have shown that this is more challenging among grain commodities farmers because of their lack of skills and the time to sift through and make sense of the datasets on the plethora of factors that influence the grain commodities market. This thesis focused on providing an answer for the main research problem that grain farmers in South Africa do not take full advantage of all the available strategies for trading their grain commodities because of the complexities associated with monitoring the large datasets that influence the grain commodities market. The main objective set by this study is to design a framework that can be followed to collect, integrate and analyse datasets that influence trading decisions of grain farmers in South Africa about grain commodities. This study takes advantage of the developments in Big Data and Data Science to achieve the set objective using the Design Science Research (DSR) methodology. The prediction of future prices of grain commodities for the different trading strategies was identified as an important factor for making better decisions when trading grain commodities and the key factors that influence the prices were identified. This was followed by a critical review of the literature to determine how the concepts of Big Data and Data Science can be leveraged for an effective grain commodities trading decision support. This resulted in a proposed framework for grain commodities trading. The proposed framework suggested an investigation of the factors that influence the prices of grain commodities as the basis for acquiring the relevant datasets. The proposed framework suggested the adoption of the Big Data approach in acquiring, preparing and integrating relevant datasets from several sources. Furthermore, it was suggested that algorithmic models for predicting grain commodities prices can be developed on top of the data layer of the proposed framework to provide real-time decision support. The proposed framework suggests the need for a carefully designed visualisation of the result and the collected data that promotes user experience. Lastly, the proposed framework included a technology consideration component to support the Big Data and Data Science approach of the framework. To demonstrate that the proposed framework addressed the main problem of this research, datasets from several sources on trading white maize in South Africa and the factors that influence market were streamed, integrated and analysed. Backpropagation Neural Network algorithm was used for modelling the prices of white maize for spot and futures trading strategies were predicted. There are other modelling techniques such as the Box-Jenkins statistical time series analysis methodology. But, Neural Networks was identified as more suitable for time series data with complex patterns and relationships. A demonstration system was setup to provide effective decision support by using near real-time data to provide a dynamic predictive analytics for the spot and December futures contract prices of white maize in South Africa. Comparative analysis of predictions made using the model from the proposed framework to actual data indicated a significant degree of accuracy. A further evaluation was carried out by asking experienced traders to make predictions for the spot and December futures contract prices of white maize. The result of the exercise indicated that the predictions from the developed model were much closer to the actual prices. This indicated that the proposed framework is technically capable and generally useful. It also shows that the proposed framework can be used to provide decision support about trading grain commodities to stakeholders with lesser skills, experience and resources. The practical contribution of this thesis is that relevant datasets from several sources can be streamed into an integrated data source in real-time, which can be used as input for a real-time learning algorithmic model for predicting grain commodities prices. This will make it possible for a predictive analytics that responds to market volatility thereby providing an effective decision support for grain commodities trading. Another practical contribution of this thesis is a proposed framework that can be followed for developing a Decision Support System for trading in grain commodities. This thesis made theoretical contributions by building on the information processing theory and the decision making theory. The theoretical contribution of this thesis consists of the identification of Big Data approach, tools and techniques for eradicating uncertainty and equivocality in grain commodities trading decision making process.
- Full Text:
- Date Issued: 2016
- Authors: Ayankoya, Kayode Anthony
- Date: 2016
- Subjects: Grain trade -- South Africa Commodity exchanges -- South Africa Food industry and trade -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11437 , vital:26925
- Description: In several countries around the world, grain commodities are traded as assets on stock exchanges. This indicate that the market and effectively the prices of the grain commodities in such countries, are controlled by several local and international economic, political and social factors that are rapidly changing. As a result, the prices of some grain commodities are volatile and trading in such commodities are prone to price-related risks. There are different trading strategies for minimising price-related risks and maximising profits. But empirical research suggests that making the right decision for effective grain commodities trading has been a difficult task for stakeholders due to high volatility of grain commodities prices. Studies have shown that this is more challenging among grain commodities farmers because of their lack of skills and the time to sift through and make sense of the datasets on the plethora of factors that influence the grain commodities market. This thesis focused on providing an answer for the main research problem that grain farmers in South Africa do not take full advantage of all the available strategies for trading their grain commodities because of the complexities associated with monitoring the large datasets that influence the grain commodities market. The main objective set by this study is to design a framework that can be followed to collect, integrate and analyse datasets that influence trading decisions of grain farmers in South Africa about grain commodities. This study takes advantage of the developments in Big Data and Data Science to achieve the set objective using the Design Science Research (DSR) methodology. The prediction of future prices of grain commodities for the different trading strategies was identified as an important factor for making better decisions when trading grain commodities and the key factors that influence the prices were identified. This was followed by a critical review of the literature to determine how the concepts of Big Data and Data Science can be leveraged for an effective grain commodities trading decision support. This resulted in a proposed framework for grain commodities trading. The proposed framework suggested an investigation of the factors that influence the prices of grain commodities as the basis for acquiring the relevant datasets. The proposed framework suggested the adoption of the Big Data approach in acquiring, preparing and integrating relevant datasets from several sources. Furthermore, it was suggested that algorithmic models for predicting grain commodities prices can be developed on top of the data layer of the proposed framework to provide real-time decision support. The proposed framework suggests the need for a carefully designed visualisation of the result and the collected data that promotes user experience. Lastly, the proposed framework included a technology consideration component to support the Big Data and Data Science approach of the framework. To demonstrate that the proposed framework addressed the main problem of this research, datasets from several sources on trading white maize in South Africa and the factors that influence market were streamed, integrated and analysed. Backpropagation Neural Network algorithm was used for modelling the prices of white maize for spot and futures trading strategies were predicted. There are other modelling techniques such as the Box-Jenkins statistical time series analysis methodology. But, Neural Networks was identified as more suitable for time series data with complex patterns and relationships. A demonstration system was setup to provide effective decision support by using near real-time data to provide a dynamic predictive analytics for the spot and December futures contract prices of white maize in South Africa. Comparative analysis of predictions made using the model from the proposed framework to actual data indicated a significant degree of accuracy. A further evaluation was carried out by asking experienced traders to make predictions for the spot and December futures contract prices of white maize. The result of the exercise indicated that the predictions from the developed model were much closer to the actual prices. This indicated that the proposed framework is technically capable and generally useful. It also shows that the proposed framework can be used to provide decision support about trading grain commodities to stakeholders with lesser skills, experience and resources. The practical contribution of this thesis is that relevant datasets from several sources can be streamed into an integrated data source in real-time, which can be used as input for a real-time learning algorithmic model for predicting grain commodities prices. This will make it possible for a predictive analytics that responds to market volatility thereby providing an effective decision support for grain commodities trading. Another practical contribution of this thesis is a proposed framework that can be followed for developing a Decision Support System for trading in grain commodities. This thesis made theoretical contributions by building on the information processing theory and the decision making theory. The theoretical contribution of this thesis consists of the identification of Big Data approach, tools and techniques for eradicating uncertainty and equivocality in grain commodities trading decision making process.
- Full Text:
- Date Issued: 2016
A gatherer’s paradise? early humans and plant foraging on the Cape south coast, South Africa
- Authors: Botha, Maria Susan
- Date: 2019
- Subjects: Plant remains (Archaeology) -- South Africa , Plant physiology Plant ecology Botany -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/37139 , vital:34124
- Description: Humans were driven to refugia during the cold and dry glacial Marine Isotope Stage 6 (MIS6) (~195–125 ka); only a few places, including the Cape south coast, show archaeological evidence of continuous human occupation. It has been hypothesised that the Cape south coast provided the requisite shelter to ensure human’s earliest survival because it provided all the right ingredients. The shores offer abundant shellfish, the land a diverse array of plants, and the climate was ameliorated due to the proximity of the then exposed Palaeo-Agulhas Plain to the warm Agulhas current. The aim of this study is to determine whether the indigenous flora of this region could have provided a sufficient edible resource for early humans. Residents of the Cape south coast have genetic ancestry linking them to the Khoe-San, the original inhabitants of the area, and still have an extensive knowledge of the local edible plants. With their help, I set out to determine a) whether humans have been utilising the same plant species over time, b) what the foraging potential of the edible plants in the region is and c) how resilient these plants are to human foraging. If we know whether the plant species known and used today were the same as those that were utilised by past humans, we can then use the contemporary knowledge to make predictions about past utilisation. To answer this question, I collated two databases: archaeological (all plant species found in archaeological sites [dating 0 to 80,000 BP]) and contemporary (all plant species in the modern-day ethnographic literature [last 400 years]) that occur within the Greater Cape Floristic Region(GCFR). I found a significant number of plant species shared between the two databases, which suggests that at least some plant species have been used by humans over a long period of time. To determine the indigenous plant foraging potential of the region, I foraged for food in the Cape south coast (451 bouts) monthly over a two-year period with the help of local inhabitants. The findings show that edible plant resources are distributed patchily and focusing on specific vegetation types would greatly enhance chances of harvesting 2,000 kcal per day, which is considered the daily calorific requirements for a typical hunter-gatherer. I then sought to understand how resilient these plants [(with an emphasis on plants with an underground storage organ (USO)] would be to human foraging. To do this, I set out plots and harvested all edible foods for three consecutive years with the help of foragers. Results indicate that there was a significant reduction in edible weight only in the third year of consecutive harvesting. In conclusion, using various approaches, this study investigates the plant food potential of the Cape south coast from the perspective of early human consumers. The findings suggest that knowledge regarding useful plants dates back to at least 80,000 BP. Food resources are patchily distributed across the main vegetation types found within the Cape south coast and occur in hotspots, i.e. concentrated areas hosting high densities of edible plant foods, surrounded by areas with very low plant food densities. Foragers could have harvested their daily calorific quota more easily if they focused their harvesting efforts in specific vegetation types found in the Cape south coast. Furthermore, many USOs circumvent climatic fluctuations, herbivory or both by staggering their emergence over multiple years, which implies they have some resilience to human foraging.
- Full Text:
- Date Issued: 2019
- Authors: Botha, Maria Susan
- Date: 2019
- Subjects: Plant remains (Archaeology) -- South Africa , Plant physiology Plant ecology Botany -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/37139 , vital:34124
- Description: Humans were driven to refugia during the cold and dry glacial Marine Isotope Stage 6 (MIS6) (~195–125 ka); only a few places, including the Cape south coast, show archaeological evidence of continuous human occupation. It has been hypothesised that the Cape south coast provided the requisite shelter to ensure human’s earliest survival because it provided all the right ingredients. The shores offer abundant shellfish, the land a diverse array of plants, and the climate was ameliorated due to the proximity of the then exposed Palaeo-Agulhas Plain to the warm Agulhas current. The aim of this study is to determine whether the indigenous flora of this region could have provided a sufficient edible resource for early humans. Residents of the Cape south coast have genetic ancestry linking them to the Khoe-San, the original inhabitants of the area, and still have an extensive knowledge of the local edible plants. With their help, I set out to determine a) whether humans have been utilising the same plant species over time, b) what the foraging potential of the edible plants in the region is and c) how resilient these plants are to human foraging. If we know whether the plant species known and used today were the same as those that were utilised by past humans, we can then use the contemporary knowledge to make predictions about past utilisation. To answer this question, I collated two databases: archaeological (all plant species found in archaeological sites [dating 0 to 80,000 BP]) and contemporary (all plant species in the modern-day ethnographic literature [last 400 years]) that occur within the Greater Cape Floristic Region(GCFR). I found a significant number of plant species shared between the two databases, which suggests that at least some plant species have been used by humans over a long period of time. To determine the indigenous plant foraging potential of the region, I foraged for food in the Cape south coast (451 bouts) monthly over a two-year period with the help of local inhabitants. The findings show that edible plant resources are distributed patchily and focusing on specific vegetation types would greatly enhance chances of harvesting 2,000 kcal per day, which is considered the daily calorific requirements for a typical hunter-gatherer. I then sought to understand how resilient these plants [(with an emphasis on plants with an underground storage organ (USO)] would be to human foraging. To do this, I set out plots and harvested all edible foods for three consecutive years with the help of foragers. Results indicate that there was a significant reduction in edible weight only in the third year of consecutive harvesting. In conclusion, using various approaches, this study investigates the plant food potential of the Cape south coast from the perspective of early human consumers. The findings suggest that knowledge regarding useful plants dates back to at least 80,000 BP. Food resources are patchily distributed across the main vegetation types found within the Cape south coast and occur in hotspots, i.e. concentrated areas hosting high densities of edible plant foods, surrounded by areas with very low plant food densities. Foragers could have harvested their daily calorific quota more easily if they focused their harvesting efforts in specific vegetation types found in the Cape south coast. Furthermore, many USOs circumvent climatic fluctuations, herbivory or both by staggering their emergence over multiple years, which implies they have some resilience to human foraging.
- Full Text:
- Date Issued: 2019
A methodology to institutionalise user experience in a South African provincial government
- Authors: Pretorius, Marco Cobus
- Date: 2012
- Subjects: Human-computer interaction , User interfaces (Computer systems) , Government Web sites -- South Africa , Web site development , Electronic government information
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10489 , http://hdl.handle.net/10948/d1019961
- Description: The number of citizens, who access e-Government websites, is growing significantly and their expectations for additional services are increasing. The Internet has become an essential instrument to distribute information to citizens. Poorly designed websites, however, can divide governments and its citizens. Consensus amongst researchers is that user experience (UX) is an important factor in designing websites specifically e-Government websites. Problems, experienced with website usability, prevent people from accessing and eventually adopting technology, such as e-Government. Countries, such as the United States, United Kingdom and Canada, have shown increased support for UX in e-Government websites. At present, a number of guidelines and design principles exists for e-Government website UX design; however, the effectiveness of the implementation of these guidelines and principles depends on the profiles of the individuals on a website development team and on an organisation’s understanding of UX. Despite the highlighted importance of UX, guidelines and principles are rarely adopted in South African e-Government websites. Usability and UX guidelines cannot be implemented; if there is no executive support; an inadequately trained staff; no routine UX practice; insufficient budget; inefficient use of usability methodologies and user-centred design (UCD) processes. The challenge at present in the UX design field is the institutionalisation of UX, specifically at government level. The goal of this research was to propose and evaluate a methodology to institutionalise UX in South African Provincial Governments (PGs), named the “Institutionalise UX in Government (IUXG) methodology”. The research used the Western Cape Government (WCG) in South Africa as a case study to evaluate the proposed methodology to institutionalise UX in a South African PG. The IUXG methodology (1.0) was proposed from five UX methodologies, as well as from best practices found in literature. The IUXG methodology (1.1) was updated, based on results of a survey to South African PGs, a survey to WCG employees, as well as literature from the WCG. The IUXG methodology (2.0) was updated a final time, based on the case study results and on a confirmation survey with WCG employees after the implementation of the case study. The research study made use of three surveys during this research. The first survey, incorporating UX maturity models, confirmed that understanding and buy-in of UX are limited and that UX maturity levels are low at South African PG level. The second and third surveys were administered to WCG e-Government website officials before and after the implementation of the IUXG methodology. The surveys measured the UX maturity level of the WCG in the component, e-Government for Citizens (e-G4C), responsible for the WCG e-Government website. The final survey results demonstrated that, after the implementation of the IUXG methodology, the WCG improved its level of UX maturity on the identified UX maturity models. Implementation of the IUXG methodology institutionalised UX in the WCG. UX activities became standard practice in the e-Government website environment after the systems development lifecycle (SDLC) incorporated UCD. UX policy, strategy and guidelines were documented for the WCG e-Government website. The WCG constructed the first usability testing facility for a South African PG and improvements to the WCG e-Government website were implemented. The proposed IUXG methodology institutionalised UX in the WCG e-Government website environment. This research is a major contribution, to addressing the current lack of UX practices in South African PGs. South African PGs can use the proposed IUXG methodology to institutionalise UX and it will assist PG officials to develop increased UX maturity levels. The advantage of the IUXG methodology is that it provides PG officials with a step-by-step method how to institutionalise UX in a PG by following the six phases of the IUXG methodology: startup, setup, organisation, method, standards and long-term. The IUXG methodology will assist South African PGs to establish UX practice as a norm. The IUXG methodology will assist PGs with the resources, methods and tools to enable them to implement UX guidelines, which will result in an improved, more usable and more user-centric PG e-Government website.
- Full Text:
- Date Issued: 2012
- Authors: Pretorius, Marco Cobus
- Date: 2012
- Subjects: Human-computer interaction , User interfaces (Computer systems) , Government Web sites -- South Africa , Web site development , Electronic government information
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10489 , http://hdl.handle.net/10948/d1019961
- Description: The number of citizens, who access e-Government websites, is growing significantly and their expectations for additional services are increasing. The Internet has become an essential instrument to distribute information to citizens. Poorly designed websites, however, can divide governments and its citizens. Consensus amongst researchers is that user experience (UX) is an important factor in designing websites specifically e-Government websites. Problems, experienced with website usability, prevent people from accessing and eventually adopting technology, such as e-Government. Countries, such as the United States, United Kingdom and Canada, have shown increased support for UX in e-Government websites. At present, a number of guidelines and design principles exists for e-Government website UX design; however, the effectiveness of the implementation of these guidelines and principles depends on the profiles of the individuals on a website development team and on an organisation’s understanding of UX. Despite the highlighted importance of UX, guidelines and principles are rarely adopted in South African e-Government websites. Usability and UX guidelines cannot be implemented; if there is no executive support; an inadequately trained staff; no routine UX practice; insufficient budget; inefficient use of usability methodologies and user-centred design (UCD) processes. The challenge at present in the UX design field is the institutionalisation of UX, specifically at government level. The goal of this research was to propose and evaluate a methodology to institutionalise UX in South African Provincial Governments (PGs), named the “Institutionalise UX in Government (IUXG) methodology”. The research used the Western Cape Government (WCG) in South Africa as a case study to evaluate the proposed methodology to institutionalise UX in a South African PG. The IUXG methodology (1.0) was proposed from five UX methodologies, as well as from best practices found in literature. The IUXG methodology (1.1) was updated, based on results of a survey to South African PGs, a survey to WCG employees, as well as literature from the WCG. The IUXG methodology (2.0) was updated a final time, based on the case study results and on a confirmation survey with WCG employees after the implementation of the case study. The research study made use of three surveys during this research. The first survey, incorporating UX maturity models, confirmed that understanding and buy-in of UX are limited and that UX maturity levels are low at South African PG level. The second and third surveys were administered to WCG e-Government website officials before and after the implementation of the IUXG methodology. The surveys measured the UX maturity level of the WCG in the component, e-Government for Citizens (e-G4C), responsible for the WCG e-Government website. The final survey results demonstrated that, after the implementation of the IUXG methodology, the WCG improved its level of UX maturity on the identified UX maturity models. Implementation of the IUXG methodology institutionalised UX in the WCG. UX activities became standard practice in the e-Government website environment after the systems development lifecycle (SDLC) incorporated UCD. UX policy, strategy and guidelines were documented for the WCG e-Government website. The WCG constructed the first usability testing facility for a South African PG and improvements to the WCG e-Government website were implemented. The proposed IUXG methodology institutionalised UX in the WCG e-Government website environment. This research is a major contribution, to addressing the current lack of UX practices in South African PGs. South African PGs can use the proposed IUXG methodology to institutionalise UX and it will assist PG officials to develop increased UX maturity levels. The advantage of the IUXG methodology is that it provides PG officials with a step-by-step method how to institutionalise UX in a PG by following the six phases of the IUXG methodology: startup, setup, organisation, method, standards and long-term. The IUXG methodology will assist South African PGs to establish UX practice as a norm. The IUXG methodology will assist PGs with the resources, methods and tools to enable them to implement UX guidelines, which will result in an improved, more usable and more user-centric PG e-Government website.
- Full Text:
- Date Issued: 2012
A model for mobile, context-aware in-car communication systems to reduce driver distractions
- Authors: Tchankue-Sielinou, Patrick
- Date: 2015
- Subjects: Automobiles -- Safety measures , Context-aware computing , Mobile communication systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4144 , vital:20556
- Description: Driver distraction remains a matter of concern throughout the world as the number of car accidents caused by distracted driving is still unacceptably high. Industry and academia are working intensively to design new techniques that will address all types of driver distraction including visual, manual, auditory and cognitive distraction. This research focuses on an existing technology, namely in-car communication systems (ICCS). ICCS allow drivers to interact with their mobile phones without touching or looking at them. Previous research suggests that ICCS have reduced visual and manual distraction. Two problems were identified in this research: existing ICCS are still expensive and only available in limited models of car. As a result of that, only a small number of drivers can obtain a car equipped with an ICCS, especially in developing countries. The second problem is that existing ICCS are not aware of the driving context, which plays a role in distracting drivers. This research project was based on the following thesis statement: A mobile, context-aware model can be designed to reduce driver distraction caused by the use of ICCS. A mobile ICCS is portable and can be used in any car, addressing the first problem. Context-awareness will be used to detect possible situations that contribute to distracting drivers and the interaction with the mobile ICCS will be adapted so as to avert calls and text messages. This will address the second problem. As the driving context is dynamic, drivers may have to deal with critical safety-related tasks while they are using an existing ICCS. The following steps were taken in order to validate the thesis statement. An investigation was conducted into the causes and consequences of driver distraction. A review of literature was conducted on context-aware techniques that could potentially be used. The design of a model was proposed, called the Multimodal Interface for Mobile Info-communication with Context (MIMIC) and a preliminary usability evaluation was conducted in order to assess the feasibility of a speech-based, mobile ICCS. Despite some problems with the speech recognition, the results were satisfying and showed that the proposed model for mobile ICCS was feasible. Experiments were conducted in order to collect data to perform supervised learning to determine the driving context. The aim was to select the most effective machine learning techniques to determine the driving context. Decision tree and instance-based algorithms were found to be the best performing algorithms. Variables such as speed, acceleration and linear acceleration were found to be the most important variables according to an analysis of the decision tree. The initial MIMIC model was updated to include several adaptation effects and the resulting model was implemented as a prototype mobile application, called MIMIC-Prototype.
- Full Text:
- Date Issued: 2015
- Authors: Tchankue-Sielinou, Patrick
- Date: 2015
- Subjects: Automobiles -- Safety measures , Context-aware computing , Mobile communication systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/4144 , vital:20556
- Description: Driver distraction remains a matter of concern throughout the world as the number of car accidents caused by distracted driving is still unacceptably high. Industry and academia are working intensively to design new techniques that will address all types of driver distraction including visual, manual, auditory and cognitive distraction. This research focuses on an existing technology, namely in-car communication systems (ICCS). ICCS allow drivers to interact with their mobile phones without touching or looking at them. Previous research suggests that ICCS have reduced visual and manual distraction. Two problems were identified in this research: existing ICCS are still expensive and only available in limited models of car. As a result of that, only a small number of drivers can obtain a car equipped with an ICCS, especially in developing countries. The second problem is that existing ICCS are not aware of the driving context, which plays a role in distracting drivers. This research project was based on the following thesis statement: A mobile, context-aware model can be designed to reduce driver distraction caused by the use of ICCS. A mobile ICCS is portable and can be used in any car, addressing the first problem. Context-awareness will be used to detect possible situations that contribute to distracting drivers and the interaction with the mobile ICCS will be adapted so as to avert calls and text messages. This will address the second problem. As the driving context is dynamic, drivers may have to deal with critical safety-related tasks while they are using an existing ICCS. The following steps were taken in order to validate the thesis statement. An investigation was conducted into the causes and consequences of driver distraction. A review of literature was conducted on context-aware techniques that could potentially be used. The design of a model was proposed, called the Multimodal Interface for Mobile Info-communication with Context (MIMIC) and a preliminary usability evaluation was conducted in order to assess the feasibility of a speech-based, mobile ICCS. Despite some problems with the speech recognition, the results were satisfying and showed that the proposed model for mobile ICCS was feasible. Experiments were conducted in order to collect data to perform supervised learning to determine the driving context. The aim was to select the most effective machine learning techniques to determine the driving context. Decision tree and instance-based algorithms were found to be the best performing algorithms. Variables such as speed, acceleration and linear acceleration were found to be the most important variables according to an analysis of the decision tree. The initial MIMIC model was updated to include several adaptation effects and the resulting model was implemented as a prototype mobile application, called MIMIC-Prototype.
- Full Text:
- Date Issued: 2015
A multiscale remote sensing assessment of subtropical indigenous forests along the wild coast, South Africa
- Authors: Blessing, Sithole Vhusomuzi
- Date: 2015
- Subjects: Forests and forestry -- South Africa -- Remote sensing , Forest conservation , Remote sensing , Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10677 , http://hdl.handle.net/10948/d1021169
- Description: The subtropical forests located along South Africa’s Wild Coast region, declared as one of the biodiversity hotspots, provide benefits to the local and national economy. However, there is evidence of increased pressure exerted on the forests by growing population and reduced income from activities not related to forest products. The ability of remote sensing to quantify subtropical forest changes over time, perform species discrimination (using field spectroscopy) and integrating field spectral and multispectral data were all assessed in this study. Investigations were conducted at pixel, leaf and sub-pixel levels. Both per-pixel and sub-pixel classification methods were used for improved forest characterisation. Using SPOT 6 imagery for 2013, the study determined the best classification algorithm for mapping sub-tropical forest and other land cover types to be the maximum likelihood classifier. Maximum likelihood outperformed minimum distance, spectral angle mapper and spectral information divergence algorithms, based on overall accuracy and Kappa coefficient values. Forest change analysis was made based on spectral measurements made at top of the atmosphere (TOC) level. When applied to the 2005 and 2009 SPOT 5 images, subtropical forest changes between 2005-2009 and 2009-2013 were quantified. A temporal analysis of forest cover trends in the periods 2005-2009 and 2009-2013 identified a decreasing trend of -3648.42 and -946.98 ha respectively, which translated to 7.81 percent and 2.20 percent decrease. Although there is evidence of a trend towards decreased rates of forest loss, more conservation efforts are required to protect the Wild Coast ecosystem. Using field spectral measurements data, the hierarchical method (comprising One-way ANOVA with Bonferroni correction, Classification and Regression Trees (CART) and Jeffries Matusita method) successfully selected optimal wavelengths for species discrimination at leaf level. Only 17 out of 2150 wavelengths were identified, thereby reducing the complexities related to data dimensionality. The optimal 17 wavelength bands were noted in the visible (438, 442, 512 and 695 nm), near infrared (724, 729, 750, 758, 856, 936, 1179, 1507 and 1673 nm) and mid-infrared (2220, 2465, 2469 and 2482 nm) portions of the electromagnetic spectrum. The Jeffries-Matusita (JM) distance method confirmed the separability of the selected wavelength bands. Using these 17 wavelengths, linear discriminant analysis (LDA) classified subtropical species at leaf level more accurately than partial least squares discriminant analysis (PLSDA) and random forest (RF). In addition, the study integrated field-collected canopy spectral and multispectral data to discriminate proportions of semi-deciduous and evergreen subtropical forests at sub-pixel level. By using the 2013 land cover (using MLC) to mask non-forested portions before sub-pixel classification (using MTMF), the proportional maps were a product of two classifiers. The proportional maps show higher proportions of evergreen forests along the coast while semi-deciduous subtropical forest species were mainly on inland parts of the Wild Coast. These maps had high accuracy, thereby proving the ability of an integration of field spectral and multispectral data in mapping semi-deciduous and evergreen forest species. Overall, the study has demonstrated the importance of the MLC and LDA and served to integrate field spectral and multispectral data in subtropical forest characterisation at both leaf and top-of-atmosphere levels. The success of both the MLC and LDA further highlighted how essential parametric classifiers are in remote sensing forestry applications. Main subtropical characteristics highlighted in this study were species discrimination at leaf level, quantifying forest change at pixel level and discriminating semi-deciduous and evergreen forests at sub-pixel level.
- Full Text:
- Date Issued: 2015
- Authors: Blessing, Sithole Vhusomuzi
- Date: 2015
- Subjects: Forests and forestry -- South Africa -- Remote sensing , Forest conservation , Remote sensing , Geographic information systems
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10677 , http://hdl.handle.net/10948/d1021169
- Description: The subtropical forests located along South Africa’s Wild Coast region, declared as one of the biodiversity hotspots, provide benefits to the local and national economy. However, there is evidence of increased pressure exerted on the forests by growing population and reduced income from activities not related to forest products. The ability of remote sensing to quantify subtropical forest changes over time, perform species discrimination (using field spectroscopy) and integrating field spectral and multispectral data were all assessed in this study. Investigations were conducted at pixel, leaf and sub-pixel levels. Both per-pixel and sub-pixel classification methods were used for improved forest characterisation. Using SPOT 6 imagery for 2013, the study determined the best classification algorithm for mapping sub-tropical forest and other land cover types to be the maximum likelihood classifier. Maximum likelihood outperformed minimum distance, spectral angle mapper and spectral information divergence algorithms, based on overall accuracy and Kappa coefficient values. Forest change analysis was made based on spectral measurements made at top of the atmosphere (TOC) level. When applied to the 2005 and 2009 SPOT 5 images, subtropical forest changes between 2005-2009 and 2009-2013 were quantified. A temporal analysis of forest cover trends in the periods 2005-2009 and 2009-2013 identified a decreasing trend of -3648.42 and -946.98 ha respectively, which translated to 7.81 percent and 2.20 percent decrease. Although there is evidence of a trend towards decreased rates of forest loss, more conservation efforts are required to protect the Wild Coast ecosystem. Using field spectral measurements data, the hierarchical method (comprising One-way ANOVA with Bonferroni correction, Classification and Regression Trees (CART) and Jeffries Matusita method) successfully selected optimal wavelengths for species discrimination at leaf level. Only 17 out of 2150 wavelengths were identified, thereby reducing the complexities related to data dimensionality. The optimal 17 wavelength bands were noted in the visible (438, 442, 512 and 695 nm), near infrared (724, 729, 750, 758, 856, 936, 1179, 1507 and 1673 nm) and mid-infrared (2220, 2465, 2469 and 2482 nm) portions of the electromagnetic spectrum. The Jeffries-Matusita (JM) distance method confirmed the separability of the selected wavelength bands. Using these 17 wavelengths, linear discriminant analysis (LDA) classified subtropical species at leaf level more accurately than partial least squares discriminant analysis (PLSDA) and random forest (RF). In addition, the study integrated field-collected canopy spectral and multispectral data to discriminate proportions of semi-deciduous and evergreen subtropical forests at sub-pixel level. By using the 2013 land cover (using MLC) to mask non-forested portions before sub-pixel classification (using MTMF), the proportional maps were a product of two classifiers. The proportional maps show higher proportions of evergreen forests along the coast while semi-deciduous subtropical forest species were mainly on inland parts of the Wild Coast. These maps had high accuracy, thereby proving the ability of an integration of field spectral and multispectral data in mapping semi-deciduous and evergreen forest species. Overall, the study has demonstrated the importance of the MLC and LDA and served to integrate field spectral and multispectral data in subtropical forest characterisation at both leaf and top-of-atmosphere levels. The success of both the MLC and LDA further highlighted how essential parametric classifiers are in remote sensing forestry applications. Main subtropical characteristics highlighted in this study were species discrimination at leaf level, quantifying forest change at pixel level and discriminating semi-deciduous and evergreen forests at sub-pixel level.
- Full Text:
- Date Issued: 2015
A new synthetic approach for preparation of Efavirenz
- Authors: Chada, Sravanthi
- Date: 2017
- Subjects: Antiretroviral agents , Asymmetric synthesis , Enzyme inhibitors , HIV (Viruses) -- Enzymes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15512 , vital:28265
- Description: Efavirenz, a drug that is still inaccessible to millions of people worldwide, is potent non nucleoside reverse transcriptase inhibitor (NNRTI), is one of the preferred agents used in combination therapy for first-line treatment of the human immunodeficiency virus (HIV). NNRTIs attach to and block an HIV enzyme called reverse transcriptase, by blocking reverse transcriptase; NNRTIs prevent HIV from multiplying and can reduce the amount of HIV in the body. Efavirenz can't cure HIV/AIDS, but taken in combination with other HIV medicines (called an HIV regimen) every day helps people with HIV live longer healthier lives. Efavirenz also reduces the risk of HIV transmission and can be used by children who are suffering from HIV/AIDS. All the above therapeutic uses of efavirenz prompted us to identify the novel and hopefully cost efficient synthetic methodology for the preparation of efavirenz. In this thesis a new synthetic method for asymmetric synthesis of efavirenz is described. This route started from commercially available starting materials and it is first established in traditional batch chemistry and further the parameters transferred to a semi continuous flow protocol for optimization.
- Full Text:
- Date Issued: 2017
- Authors: Chada, Sravanthi
- Date: 2017
- Subjects: Antiretroviral agents , Asymmetric synthesis , Enzyme inhibitors , HIV (Viruses) -- Enzymes
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/15512 , vital:28265
- Description: Efavirenz, a drug that is still inaccessible to millions of people worldwide, is potent non nucleoside reverse transcriptase inhibitor (NNRTI), is one of the preferred agents used in combination therapy for first-line treatment of the human immunodeficiency virus (HIV). NNRTIs attach to and block an HIV enzyme called reverse transcriptase, by blocking reverse transcriptase; NNRTIs prevent HIV from multiplying and can reduce the amount of HIV in the body. Efavirenz can't cure HIV/AIDS, but taken in combination with other HIV medicines (called an HIV regimen) every day helps people with HIV live longer healthier lives. Efavirenz also reduces the risk of HIV transmission and can be used by children who are suffering from HIV/AIDS. All the above therapeutic uses of efavirenz prompted us to identify the novel and hopefully cost efficient synthetic methodology for the preparation of efavirenz. In this thesis a new synthetic method for asymmetric synthesis of efavirenz is described. This route started from commercially available starting materials and it is first established in traditional batch chemistry and further the parameters transferred to a semi continuous flow protocol for optimization.
- Full Text:
- Date Issued: 2017
Advanced high speed data and clock transmission over optical fibre for square kilometre telescope array
- Authors: Isoe, George Mosoti
- Date: 2018
- Subjects: Very large array telescopes -- South Africa , Semiconductor lasers Optical communications Optical amplifiers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30375 , vital:30935
- Description: There is an ever present need from Internet users for more bandwidth. This is manifested by continuous increase in bandwidth demanding applications such as 5G wireless, new end user consumer links like thunderbolt, video conferencing, high definition video-on-demand transmitted over the Internet and massive data transfers required with and within data centres for backup, storage and data processing in cloud computing. Fibre optic communications technologies are playing a pivotal role in communication, being a major enabling technology in our increasingly Internet-centric society. As network services continue to become more dynamic and diverse, Internet service providers are faced with a challenge of cost reduction in the transmission network, power and spectral efficiency as well as scalability of the optical network infrastructure to support incremental expansions and virtual machines. Intelligent design of terrestrial optical networks to allow for simultaneous signal transmission through shared network infrastructure, and the use of low cost, power efficient, high bandwidth transmitters such as vertical surface emitting lasers (VCSELs) as well as exploitation of spectral efficient in-complex advanced modulation formats is a viable approach to this situation. In this study, techniques for spectral efficiency upgrade and simultaneous transmission of data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) over shared infrastructure have experimentally been optimized in a laboratory environment for adoption in next-generation telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time(UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres. This work starts by experimentally optimizing VCSEL technology for simultaneous transmission of 10 Gbps data and 1.712 GHz RF clock signal over a single G. 655 optical fibre of length 24.75 Km at different channel spacing and different propagation direction for implementation in a cost effective next-generation telescope array network. The wavelength tuneability property of VCSEL transmitters allows for wavelength adjustment, a key requirement for simultaneous data and RF clock signal transmission over a single optical fibre. A receiver sensitivity of -19.19 dBm was experimentally achieved at back-to-back analysis. A 24.75 Km of simultaneous data and RF clock signal transmission performed at 0.4 nm channel spacing introduced a transmission penalty of 1.07 dB and 1.63 dB for counter and co-propagation scheme respectively. This work mainly utilized direct modulation and direct detection using a positive intrinsic negative (PIN) due to its simplicity and cost effectiveness. A novel modulation technique for simultaneous data and polarization-based pulse-per-second timing clock signal transmission using a single VCSEL carrier is experimentally demonstrated. Two signal types, a directly modulated 10 Gbps data signal and a polarization-based pulse per second (PPS) clock signal are modulated onto a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm. Spectral efficiency is maximized by exploiting the inherent orthogonal polarization switching of the xiv VCSEL with changing bias in transmission of the PPS signal. A 10 Gbps VCSEL transmission with PPS over 11 Km of G.652 fibre introduced a transmission penalty of 0.52 dB. The contribution of PPS clock signal to this penalty was found to be 0.08 dB. A technique for simultaneous directly modulated data and phase modulated reference clock signal transmission over a signal channel in wavelength division multiplexing (WDM) solutions is experimentally demonstrated. This is to prepare solutions to the ever-increasing demand over gigabit/s, terabit/s and gigahertz capacities in WDM-based terrestrial optical fibre transmission systems such as telescope array networks. a total capacity of 30 Gbps (310 Gbps) data and 12 GHz ( 4 3 GHz) reference clock signal are multiplexed at a channel spacing of 100 GHz and simultaneously transmitted over a single mode G.655 fibre of length 24.73 Km. The recovery of the phase modulated RF clock signal using a differential delay line interferometry technique is experimentally demonstrated. A 625 Gbps (2525 Gbps) DWDM data transmission system is further implemented in simulation by multiplexing 25 channels at 25 Gbps per channel using 50 GHz channel spacing. A four level pulse amplitude modulation (4-PAM) data modulation format employing VCSELs is experimentally demonstrated for adoption in high bitrate networks such as big data science projects and data centre networks. 4-PAM offers a good trade-off between complexity, efficiency, reach, and sensitivity. A software defined digital signal processing (DSP) receiver is designed and implemented in MATLAB to recover the transmitted 4-PAM data signal cost effectively without the necessity of costly receiver hardware. A novel technique for maximizing carrier spectral efficiency through simultaneous 20 Gbps 4-PAM data and phase modulated 2 GHz RF clock signal transmission on a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm is experimentally demonstrated for the first time to the best of our knowledge. Data transmission and clock stability performance of the designed high spectral efficient VCSEL-based link network is evaluated through BER curve plots, phase noise measurements and Allan variance analysis respectively. VCSEL-based Raman amplification is experimentally demonstrated as a viable approach for RF clock signal distribution in extended reach astronomical telescope array networks and other extended reach terrestrial optical fibre network application. This is achieved by adopting two pumping techniques namely forward pumping and backward pumping. A maximum on off gain of 5.7 dB and 1.5 dB was experimentally attained for forward pumping and backward pumping at 24 dBm pump power respectively, while a maximum 100.8 Km fibre transmission achieved experimentally. In summary, this study has successfully demonstrated in-complex, spectral efficient, low cost and power efficient simultaneous data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) transmission techniques over shared network infrastructure. Simultaneous transmission of data, RF clock and PPS timing signal is relevant in nextgeneration telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time (UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres.
- Full Text:
- Date Issued: 2018
- Authors: Isoe, George Mosoti
- Date: 2018
- Subjects: Very large array telescopes -- South Africa , Semiconductor lasers Optical communications Optical amplifiers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/30375 , vital:30935
- Description: There is an ever present need from Internet users for more bandwidth. This is manifested by continuous increase in bandwidth demanding applications such as 5G wireless, new end user consumer links like thunderbolt, video conferencing, high definition video-on-demand transmitted over the Internet and massive data transfers required with and within data centres for backup, storage and data processing in cloud computing. Fibre optic communications technologies are playing a pivotal role in communication, being a major enabling technology in our increasingly Internet-centric society. As network services continue to become more dynamic and diverse, Internet service providers are faced with a challenge of cost reduction in the transmission network, power and spectral efficiency as well as scalability of the optical network infrastructure to support incremental expansions and virtual machines. Intelligent design of terrestrial optical networks to allow for simultaneous signal transmission through shared network infrastructure, and the use of low cost, power efficient, high bandwidth transmitters such as vertical surface emitting lasers (VCSELs) as well as exploitation of spectral efficient in-complex advanced modulation formats is a viable approach to this situation. In this study, techniques for spectral efficiency upgrade and simultaneous transmission of data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) over shared infrastructure have experimentally been optimized in a laboratory environment for adoption in next-generation telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time(UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres. This work starts by experimentally optimizing VCSEL technology for simultaneous transmission of 10 Gbps data and 1.712 GHz RF clock signal over a single G. 655 optical fibre of length 24.75 Km at different channel spacing and different propagation direction for implementation in a cost effective next-generation telescope array network. The wavelength tuneability property of VCSEL transmitters allows for wavelength adjustment, a key requirement for simultaneous data and RF clock signal transmission over a single optical fibre. A receiver sensitivity of -19.19 dBm was experimentally achieved at back-to-back analysis. A 24.75 Km of simultaneous data and RF clock signal transmission performed at 0.4 nm channel spacing introduced a transmission penalty of 1.07 dB and 1.63 dB for counter and co-propagation scheme respectively. This work mainly utilized direct modulation and direct detection using a positive intrinsic negative (PIN) due to its simplicity and cost effectiveness. A novel modulation technique for simultaneous data and polarization-based pulse-per-second timing clock signal transmission using a single VCSEL carrier is experimentally demonstrated. Two signal types, a directly modulated 10 Gbps data signal and a polarization-based pulse per second (PPS) clock signal are modulated onto a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm. Spectral efficiency is maximized by exploiting the inherent orthogonal polarization switching of the xiv VCSEL with changing bias in transmission of the PPS signal. A 10 Gbps VCSEL transmission with PPS over 11 Km of G.652 fibre introduced a transmission penalty of 0.52 dB. The contribution of PPS clock signal to this penalty was found to be 0.08 dB. A technique for simultaneous directly modulated data and phase modulated reference clock signal transmission over a signal channel in wavelength division multiplexing (WDM) solutions is experimentally demonstrated. This is to prepare solutions to the ever-increasing demand over gigabit/s, terabit/s and gigahertz capacities in WDM-based terrestrial optical fibre transmission systems such as telescope array networks. a total capacity of 30 Gbps (310 Gbps) data and 12 GHz ( 4 3 GHz) reference clock signal are multiplexed at a channel spacing of 100 GHz and simultaneously transmitted over a single mode G.655 fibre of length 24.73 Km. The recovery of the phase modulated RF clock signal using a differential delay line interferometry technique is experimentally demonstrated. A 625 Gbps (2525 Gbps) DWDM data transmission system is further implemented in simulation by multiplexing 25 channels at 25 Gbps per channel using 50 GHz channel spacing. A four level pulse amplitude modulation (4-PAM) data modulation format employing VCSELs is experimentally demonstrated for adoption in high bitrate networks such as big data science projects and data centre networks. 4-PAM offers a good trade-off between complexity, efficiency, reach, and sensitivity. A software defined digital signal processing (DSP) receiver is designed and implemented in MATLAB to recover the transmitted 4-PAM data signal cost effectively without the necessity of costly receiver hardware. A novel technique for maximizing carrier spectral efficiency through simultaneous 20 Gbps 4-PAM data and phase modulated 2 GHz RF clock signal transmission on a single mode 10 GHz bandwidth VCSEL carrier at 1310 nm is experimentally demonstrated for the first time to the best of our knowledge. Data transmission and clock stability performance of the designed high spectral efficient VCSEL-based link network is evaluated through BER curve plots, phase noise measurements and Allan variance analysis respectively. VCSEL-based Raman amplification is experimentally demonstrated as a viable approach for RF clock signal distribution in extended reach astronomical telescope array networks and other extended reach terrestrial optical fibre network application. This is achieved by adopting two pumping techniques namely forward pumping and backward pumping. A maximum on off gain of 5.7 dB and 1.5 dB was experimentally attained for forward pumping and backward pumping at 24 dBm pump power respectively, while a maximum 100.8 Km fibre transmission achieved experimentally. In summary, this study has successfully demonstrated in-complex, spectral efficient, low cost and power efficient simultaneous data signal, reference frequency (RF) clock signal and pulse-per-second (PPS) transmission techniques over shared network infrastructure. Simultaneous transmission of data, RF clock and PPS timing signal is relevant in nextgeneration telescope array networks such as the Square Kilometre Array (SKA), time keeping systems such as banking systems, Coordinated Universal Time (UTC) timing and Global Positioning Systems (GPS), as well as high capacity spectral efficient short reach optical fibre networks such as data centres.
- Full Text:
- Date Issued: 2018
Advances in platinum-amine chemotherapeutic agents : their chemistry and applicationc
- Authors: Jaganath, Yatish
- Date: 2009
- Subjects: Coordination compounds , Antineoplastic antibiotics , Cancer -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10446 , http://hdl.handle.net/10948/d1021222
- Description: The research conducted in this study focussed on advancing the knowledge database of diamineplatinum complexes on two frontiers: 1) the development of novel anticancer complexes, and 2) improvements in their synthetic chemistry. Novel square-planar dichloro and oxalato platinum(II) complexes were synthesized as potential anticancer agents in accordance with a comprehensive set of factors identified as being significant in optimizing such action. The nonleaving ligands consisted of asymmetric chelating chiral diamines of the form 1- (1-R-imidazol-2yl)(R')methanamine (R representing methyl, butyl and R' methyl, phenyl). The complexes were characterized by a host of spectral, thermal and crystallographic techniques. In addition, the stabilities of the complexes were monitored in aqueous and saline solutions. Cytotoxicity screening on three cultured cancer cell lines (MCF-7, HeLa and HT29) indicated the compounds, present as their respective racemates, to have rather modest activities relative to cisplatin; with complexes having the smallest substituents, R,R' = methyl, being most active. In recognition of the limitations of traditional silver-based syntheses of oxalatoplatinum(II) complexes, innovative non-silver methods were developed using the well known cancer drug, oxaliplatin, (trans-R,R-1,2- diaminocyclohexane)oxalatoplatinum(II), as a prototype. These involved direct ligand exchange reactions of the dichloro precursor, (trans-R,R-1,2- diaminocyclohexane)dichloroplatinum(II), with tetrabutylammonium oxalate in essentially non-aqueous solvents. A 90:10 mixture of isoamyl alcohol (3-methyl- 1-butanol):water, proved to be a promising solvent, enabling the recovery of pure oxaliplatin (~98 percent) after 9 hours at 88 °C in yields of up to 86 percent. In light of the perceived unique mode of anticancer action available to mononitroplatinum(IV) complexes (i.e. their STAT3-binding potential), octahedral diamineoxalatoplatinum(IV) complexes containing axially-coordinated nitro and halo co-ligands were synthesized and extensively characterized. Electrochemical studies revealed trends in reduction potential which could be correlated to structural / chemical traits of the coordinated diamine and axial ligands. The similarities of the determined cytotoxicities of the platinum(IV) compounds and their respective platinum(II) analogues, implicated reduction as a means of activation of the platinum(IV) complexes.
- Full Text:
- Date Issued: 2009
- Authors: Jaganath, Yatish
- Date: 2009
- Subjects: Coordination compounds , Antineoplastic antibiotics , Cancer -- Chemotherapy
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10446 , http://hdl.handle.net/10948/d1021222
- Description: The research conducted in this study focussed on advancing the knowledge database of diamineplatinum complexes on two frontiers: 1) the development of novel anticancer complexes, and 2) improvements in their synthetic chemistry. Novel square-planar dichloro and oxalato platinum(II) complexes were synthesized as potential anticancer agents in accordance with a comprehensive set of factors identified as being significant in optimizing such action. The nonleaving ligands consisted of asymmetric chelating chiral diamines of the form 1- (1-R-imidazol-2yl)(R')methanamine (R representing methyl, butyl and R' methyl, phenyl). The complexes were characterized by a host of spectral, thermal and crystallographic techniques. In addition, the stabilities of the complexes were monitored in aqueous and saline solutions. Cytotoxicity screening on three cultured cancer cell lines (MCF-7, HeLa and HT29) indicated the compounds, present as their respective racemates, to have rather modest activities relative to cisplatin; with complexes having the smallest substituents, R,R' = methyl, being most active. In recognition of the limitations of traditional silver-based syntheses of oxalatoplatinum(II) complexes, innovative non-silver methods were developed using the well known cancer drug, oxaliplatin, (trans-R,R-1,2- diaminocyclohexane)oxalatoplatinum(II), as a prototype. These involved direct ligand exchange reactions of the dichloro precursor, (trans-R,R-1,2- diaminocyclohexane)dichloroplatinum(II), with tetrabutylammonium oxalate in essentially non-aqueous solvents. A 90:10 mixture of isoamyl alcohol (3-methyl- 1-butanol):water, proved to be a promising solvent, enabling the recovery of pure oxaliplatin (~98 percent) after 9 hours at 88 °C in yields of up to 86 percent. In light of the perceived unique mode of anticancer action available to mononitroplatinum(IV) complexes (i.e. their STAT3-binding potential), octahedral diamineoxalatoplatinum(IV) complexes containing axially-coordinated nitro and halo co-ligands were synthesized and extensively characterized. Electrochemical studies revealed trends in reduction potential which could be correlated to structural / chemical traits of the coordinated diamine and axial ligands. The similarities of the determined cytotoxicities of the platinum(IV) compounds and their respective platinum(II) analogues, implicated reduction as a means of activation of the platinum(IV) complexes.
- Full Text:
- Date Issued: 2009
Aerial optical fibres in telecommunication systems : SOP and PMD monitoring, and tolerance of modulation formats
- Authors: Ireeta, Winston Tumps
- Date: 2010
- Subjects: Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10542 , http://hdl.handle.net/10948/1478 , http://hdl.handle.net/10948/d1012894 , Optical communications , Fiber optics
- Description: The topic of this thesis is aerial optical fibres in telecommunication systems: state of polarization (SOP) and polarization mode dispersion (PMD) monitoring and tolerance of modulation formats. Errors in optical fibre telecommunication systems are introduced when these polarization effects (SOP and PMD) change. These changes are so intense especially in aerial optical fibres. Part of the backbone of South Africa’s national grid includes long distances of aerial optical fibre between transmission exchange stations. The work in this thesis can be divided into three parts which all deal with the major aspects of PMD in deployed aerial optical fibres: characterization, environmental effects plus other perturbations, and tolerance of different modulation formats. In our work, SOP and PMD field measurements revealed that they both fluctuate more rapidly in deployed aerial optical fibres especially on windy and hot days. The SOP and PMD changes in the aerial optical fibres showed a significant correlation with these environmental parameters. SOP and PMD are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. In our work, with only 184 PMD values measured and obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47 ps and standard deviation of 0.08 ps. This small standard deviation was justification for its robustness and accuracy. The statistical distributions for first-order polarization mode dispersion (FO-PMD) and second-order polarization mode dispersion (SO-PMD) for the first time were experimentally confirmed when measured using the FTB-5700 single-ended dispersion analyzer instrument for deployed aerial optical fibres. We were also able to determine the time scale over which to compensate FO-PMD in deployed aerial fibres using the directional time drift autocorrelation function method. It is slightly higher than 390 s for SOP measurements made on a particular windy and hot day. This is due to the fact that the changes of the PMD vector are known to be slower than the SOP changes. vi We also investigated the theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fibre) or with time (for aerial fibre). Our results showed that the statistics of the relative SOP changes approached the distribution proposed by Foschini et al. (2000). Advanced optical modulation formats have become a key ingredient in the design of modern state-of-the-art wavelength-division-multiplexed (WDM) optical transmission systems. In our work, we investigated which of these advanced modulation formats is best suited for the South African network especially on systems that have links of aerial optical fibres. Keywords: aerial optical fibre, polarization mode dispersion (PMD), principal states of polarization (PSP), state of polarization (SOP), first-order PMD, second-order PMD.
- Full Text:
- Date Issued: 2010
- Authors: Ireeta, Winston Tumps
- Date: 2010
- Subjects: Optical communications , Fiber optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10542 , http://hdl.handle.net/10948/1478 , http://hdl.handle.net/10948/d1012894 , Optical communications , Fiber optics
- Description: The topic of this thesis is aerial optical fibres in telecommunication systems: state of polarization (SOP) and polarization mode dispersion (PMD) monitoring and tolerance of modulation formats. Errors in optical fibre telecommunication systems are introduced when these polarization effects (SOP and PMD) change. These changes are so intense especially in aerial optical fibres. Part of the backbone of South Africa’s national grid includes long distances of aerial optical fibre between transmission exchange stations. The work in this thesis can be divided into three parts which all deal with the major aspects of PMD in deployed aerial optical fibres: characterization, environmental effects plus other perturbations, and tolerance of different modulation formats. In our work, SOP and PMD field measurements revealed that they both fluctuate more rapidly in deployed aerial optical fibres especially on windy and hot days. The SOP and PMD changes in the aerial optical fibres showed a significant correlation with these environmental parameters. SOP and PMD are stochastic in nature due to changes in the properties of the optical fibres and its positions because of both intrinsic and extrinsic perturbations. In our work, with only 184 PMD values measured and obtained by use of the FTB-5700 single-ended dispersion analyzer, the predicted theoretical Gaussian fit was obtained with a mean of 0.47 ps and standard deviation of 0.08 ps. This small standard deviation was justification for its robustness and accuracy. The statistical distributions for first-order polarization mode dispersion (FO-PMD) and second-order polarization mode dispersion (SO-PMD) for the first time were experimentally confirmed when measured using the FTB-5700 single-ended dispersion analyzer instrument for deployed aerial optical fibres. We were also able to determine the time scale over which to compensate FO-PMD in deployed aerial fibres using the directional time drift autocorrelation function method. It is slightly higher than 390 s for SOP measurements made on a particular windy and hot day. This is due to the fact that the changes of the PMD vector are known to be slower than the SOP changes. vi We also investigated the theoretical statistical distribution that corresponds to output SOP variations. The SOP variations can either be with wavelength (for buried fibre) or with time (for aerial fibre). Our results showed that the statistics of the relative SOP changes approached the distribution proposed by Foschini et al. (2000). Advanced optical modulation formats have become a key ingredient in the design of modern state-of-the-art wavelength-division-multiplexed (WDM) optical transmission systems. In our work, we investigated which of these advanced modulation formats is best suited for the South African network especially on systems that have links of aerial optical fibres. Keywords: aerial optical fibre, polarization mode dispersion (PMD), principal states of polarization (PSP), state of polarization (SOP), first-order PMD, second-order PMD.
- Full Text:
- Date Issued: 2010
An ecosystem-based spatial conservation plan for the South African sandy beaches
- Authors: Harris, Linda Rozanne
- Date: 2012
- Subjects: Seashore -- South Africa , Bathing beaches -- South Africa , Shorelines -- South Africa , Conservation biology , PhD Thesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10688 , http://hdl.handle.net/10948/d1007920 , Seashore -- South Africa , Bathing beaches -- South Africa , Shorelines -- South Africa , Conservation biology
- Description: An ecosytem-based spatial conservation plan for the South African sandy beaches. Sandy beaches are valuable ecosystems. They support a collection of species that is unique, comprising many endemic species, and provide a number of key ecosystem goods and services, including scenic vistas for human recreation, nesting sites for turtles and birds, and important areas for biogeochemical recycling, water filtration and purification. However, sandy beaches have not been well understood or appreciated as ecosystems, and consequently have a legacy of poor coastal management. In many instances this has lead to a "tyranny of small decisions", where multiple, seemingly insignificant management decisions and actions have resulted in complete transformation and degradation of the shoreline in several places. In addition to inappropriate management strategies, beaches are also poorly represented in conservation areas. Further, where they are recognised as being "conserved" in marine protected areas, this often is a false sense of protection because the far more sensitive dune portion of the littoral active zone is invariably not included in the reserve. In short, there is a need for a new way to approach sandy beach conservation and management that includes the system (dunes, intertidal beaches and surf zones) as a whole. On one hand, the approach should make provision for use of the abundant natural resources and opportunities associated with sandy shores in ways that are sustainable and contribute to biodiversity stewardship - through ecosystem-based management and marine spatial planning. But, on the other hand, it must simultaneously contribute to securing a sufficient amount of the key ecological attributes of beaches (habitats, biodiversity and processes) in a network of reserves, to ensure that the ecosystem, natural resources, and services all persist in perpetuity - through systematic conservation planning. The aim of this Thesis is to integrate these into a single approach, which I call ecosystem-based spatial conservation planning for sandy beaches, using the South African sandy shores as a case study. To achieve this broad aim, the Thesis is divided into three parts. Part 1 deals with establishing baseline information by quantifying spatial patterns in sandy beach habitats (Chapter 1), biodiversity, key assemblages and processes, and outstanding physical features (Chapter 2). First, mapping sandy beach habitats is a challenge given the vast, linear extent of shorelines and significant resources required to complete the project. Therefore, a novel approach was derived using statistical techniques (conditional inference trees) to identify physical features of beaches that can be observed on Google Earth (or similar) imagery, and that can provide good predictions of beach morphodynamic (habitat) types. Based on the results of this analysis, sandy beaches (and all other coastal habitat types) were mapped digitally in ArcGIS. Second, spatial patterns in sandy beach biodiversity (vertebrates, macrofauna, microflora and foredune plants) were mapped by compiling existing data on the distributions of key species that have been well studied or mapped previously (vertebrates and foredune plants), and by niche modelling (macrofauna and microflora). For the latter, data from all previous sandy-beach sampling events in South Africa were compiled from published and unpublished sources, and supplemented with additional sampling of 23 beaches along the national shoreline, targeting macrofauna and phytoplankton. Altogether, the macrofauna database comprised data from 135 sites and 186 sampling events, and the microflora (phytoplankton and microphytobenthos) database comprised data from 73 sites and 510 samples. The probabilistic distribution of each "resident" species (present at 10 or more sites) was modelled in MaxEnt version 3.3.3k, probability thresholds were determined statistically (to convert the data into predicted presence-absence), and displayed as a digital map. A composite biodiversity map was compiled, and key trends in species richness and endemism along the national shoreline were quantified. To supplement biodiversity proper, additional valued-features of sandy beaches were mapped, including: important assemblages; unique habitat features; and sites associated with key ecological processes. Part 2 considers threats to sandy beaches in the context of deriving an appropriate management strategy that seeks to provide for use of the coast, but in a way that has least overall impact to the ecosystem. A method for assessing cumulative threats to sandy beaches is adapted from an existing framework (Chapter 4). This entailed compiling a list of threats to beaches, and scoring these (out of 10) in terms of the severity of their respective impacts to beaches, and how long it would take the ecosystem to recover should the threat be removed. The scoring was based on the collective expert opinion of the scientific community working on sandy beaches, at a workshop during the VIth International Sandy Beach Symposium 2012. To standardize the scores and ensure broad applicability, a base case scenario of a pristine beach was established, and maximum theoretical scores were provided for this context. The method for integrating these scores into a spatial, cumulative threat assessment was then determined. In Chapter 5, the maximum theoretical scores (from Chapter 4) were down-scaled to suit the current threat regime to the South African sandy beaches, and the cumulative threat assessment methodology was applied. From this analysis, the most threatened beaches in South Africa, and the most important threats were highlighted. A decision-support tool for managers was derived from the site-specific cumulative threat-impact scores, based first on the degree of permanent habitat transformation, and second on the cumulative impact of other stressors where the impacts these stressors have could potentially be mitigated or ameliorated. Part 3 concerns conservation of beaches explicitly. It addresses how much of which valued features of beaches is required to ensure their long-term persistence, and the design of a network of beaches in South Africa that are of ecological importance and should be set aside as reserves. Conservation targets are set in Chapter 6, using species-area curves to determine a baseline percentage-area required to protect sandy beach habitats, which is modified using heuristic principles based on habitat rarity and threat status (from a recent national assessment). A fixed target was applied to all species, also modified by heuristic principles, and another fixed target was applied to key assemblages and processes.
- Full Text:
- Date Issued: 2012
- Authors: Harris, Linda Rozanne
- Date: 2012
- Subjects: Seashore -- South Africa , Bathing beaches -- South Africa , Shorelines -- South Africa , Conservation biology , PhD Thesis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10688 , http://hdl.handle.net/10948/d1007920 , Seashore -- South Africa , Bathing beaches -- South Africa , Shorelines -- South Africa , Conservation biology
- Description: An ecosytem-based spatial conservation plan for the South African sandy beaches. Sandy beaches are valuable ecosystems. They support a collection of species that is unique, comprising many endemic species, and provide a number of key ecosystem goods and services, including scenic vistas for human recreation, nesting sites for turtles and birds, and important areas for biogeochemical recycling, water filtration and purification. However, sandy beaches have not been well understood or appreciated as ecosystems, and consequently have a legacy of poor coastal management. In many instances this has lead to a "tyranny of small decisions", where multiple, seemingly insignificant management decisions and actions have resulted in complete transformation and degradation of the shoreline in several places. In addition to inappropriate management strategies, beaches are also poorly represented in conservation areas. Further, where they are recognised as being "conserved" in marine protected areas, this often is a false sense of protection because the far more sensitive dune portion of the littoral active zone is invariably not included in the reserve. In short, there is a need for a new way to approach sandy beach conservation and management that includes the system (dunes, intertidal beaches and surf zones) as a whole. On one hand, the approach should make provision for use of the abundant natural resources and opportunities associated with sandy shores in ways that are sustainable and contribute to biodiversity stewardship - through ecosystem-based management and marine spatial planning. But, on the other hand, it must simultaneously contribute to securing a sufficient amount of the key ecological attributes of beaches (habitats, biodiversity and processes) in a network of reserves, to ensure that the ecosystem, natural resources, and services all persist in perpetuity - through systematic conservation planning. The aim of this Thesis is to integrate these into a single approach, which I call ecosystem-based spatial conservation planning for sandy beaches, using the South African sandy shores as a case study. To achieve this broad aim, the Thesis is divided into three parts. Part 1 deals with establishing baseline information by quantifying spatial patterns in sandy beach habitats (Chapter 1), biodiversity, key assemblages and processes, and outstanding physical features (Chapter 2). First, mapping sandy beach habitats is a challenge given the vast, linear extent of shorelines and significant resources required to complete the project. Therefore, a novel approach was derived using statistical techniques (conditional inference trees) to identify physical features of beaches that can be observed on Google Earth (or similar) imagery, and that can provide good predictions of beach morphodynamic (habitat) types. Based on the results of this analysis, sandy beaches (and all other coastal habitat types) were mapped digitally in ArcGIS. Second, spatial patterns in sandy beach biodiversity (vertebrates, macrofauna, microflora and foredune plants) were mapped by compiling existing data on the distributions of key species that have been well studied or mapped previously (vertebrates and foredune plants), and by niche modelling (macrofauna and microflora). For the latter, data from all previous sandy-beach sampling events in South Africa were compiled from published and unpublished sources, and supplemented with additional sampling of 23 beaches along the national shoreline, targeting macrofauna and phytoplankton. Altogether, the macrofauna database comprised data from 135 sites and 186 sampling events, and the microflora (phytoplankton and microphytobenthos) database comprised data from 73 sites and 510 samples. The probabilistic distribution of each "resident" species (present at 10 or more sites) was modelled in MaxEnt version 3.3.3k, probability thresholds were determined statistically (to convert the data into predicted presence-absence), and displayed as a digital map. A composite biodiversity map was compiled, and key trends in species richness and endemism along the national shoreline were quantified. To supplement biodiversity proper, additional valued-features of sandy beaches were mapped, including: important assemblages; unique habitat features; and sites associated with key ecological processes. Part 2 considers threats to sandy beaches in the context of deriving an appropriate management strategy that seeks to provide for use of the coast, but in a way that has least overall impact to the ecosystem. A method for assessing cumulative threats to sandy beaches is adapted from an existing framework (Chapter 4). This entailed compiling a list of threats to beaches, and scoring these (out of 10) in terms of the severity of their respective impacts to beaches, and how long it would take the ecosystem to recover should the threat be removed. The scoring was based on the collective expert opinion of the scientific community working on sandy beaches, at a workshop during the VIth International Sandy Beach Symposium 2012. To standardize the scores and ensure broad applicability, a base case scenario of a pristine beach was established, and maximum theoretical scores were provided for this context. The method for integrating these scores into a spatial, cumulative threat assessment was then determined. In Chapter 5, the maximum theoretical scores (from Chapter 4) were down-scaled to suit the current threat regime to the South African sandy beaches, and the cumulative threat assessment methodology was applied. From this analysis, the most threatened beaches in South Africa, and the most important threats were highlighted. A decision-support tool for managers was derived from the site-specific cumulative threat-impact scores, based first on the degree of permanent habitat transformation, and second on the cumulative impact of other stressors where the impacts these stressors have could potentially be mitigated or ameliorated. Part 3 concerns conservation of beaches explicitly. It addresses how much of which valued features of beaches is required to ensure their long-term persistence, and the design of a network of beaches in South Africa that are of ecological importance and should be set aside as reserves. Conservation targets are set in Chapter 6, using species-area curves to determine a baseline percentage-area required to protect sandy beach habitats, which is modified using heuristic principles based on habitat rarity and threat status (from a recent national assessment). A fixed target was applied to all species, also modified by heuristic principles, and another fixed target was applied to key assemblages and processes.
- Full Text:
- Date Issued: 2012
An evaluation and comparison of the plasticiser effects of p -Menthane-3,8-diol-citronellal acetal plasticiser with triethyl citrate and bis(2-ethylhexyl) terephthalate on ethylcellulose films.
- Authors: Marx, Johannes Scheepers
- Date: 2019
- Subjects: Plasticisers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44629 , vital:38164
- Description: In recent years, much attention has been focused on research to replace petroleumbased commodity plastics, in a cost-effective manner, with biodegradable materials offering competitive mechanical properties. The use of natural and/or biodegradable plasticisers, with low toxicity and good compatibility with several plastics, resins, rubber and elastomers in substitution of conventional plasticisers, such as phthalates and other synthetic plasticisers attract the market along with the increasing worldwide trend towards the use of bio-polymers. The main research objective entailed the behaviour of the novel bio-plasticiser PMDcitronellal acetal (PMD-CA) and its comparison with other commercial bio-plasticiser, triethyl citrate (TEC) and a non-phthalate plasticiser bis(2-ethylhexyl) terephthalate (DOTP), on ethylcellulose (EC) films to evaluate whether it would be feasible to replace them with PMD-CA. The films were produced by a casting technique and were characterised by mechanical properties, thermoanalysis, Scanning Electron Microscopy, disintegration and Fourier-Transform Infrared (FT-IR) spectroscopy. The addition of any of the three plasticisers to EC film increased the flexibility of the films. The plasticisers PMD-CA and DOTP added to EC formed tougher films as compared to EC films containing TEC shown by the high % elongation at break, strain and displacement. Statistically, it was proved that PMD-CA and DOTP had a more significant effect on % elongation of EC films than TEC, postulated to be due to their similar molecular size and structure. Thermoanalytical studies conducted revealed that the thermal degradation process of EC films proceeded in three basic stages, namely dehydration, depolymerisation and pyrolytic decomposition. Thermoanalytical analysis showed that unplasticised EC films had a higher glass transition value compared to the films containing any of the plasticisers and that PMD-CA and DOTP are more effective plasticisers compared to TEC due to their lower glass transition temperatures. The presence of plasticisers in the polymer matrix did change the surface morphology of polymer films. The addition of hydroxypropyl methylcellulose (HPMC) to EC PMD-CA and EC DOTP films caused more significant globule-like bubbles which were not uniform in size on the surface of these films. Observations were made that the type of plasticiser coating with or without pore former influenced the disintegration properties of films. HPMC, as pore former, played a significant role in the drug release system matrix. EC PMD-CA and EC DOTP polymeric films controlled the disintegration of the films in the acidic and weakly acidic medium. EC and EC TEC films had less significant control on the disintegration rate of the acidic and weakly acidic disintegration media. FT-IR characterisation of the films revealed comparable peaks observed in all the polymer-plasticiser combinations and therefore it was concluded that chemical interactions did not exist between the polymers and plasticisers. Added excipients (plasticisers and pore formers) were found to be compatible with EC films. It was concluded within the scope of this research that EC films plasticised with PMDCA, DOTP or TEC outperformed film properties of those compared to unplasticised EC film. The plasticising properties of the novel bio-plasticiser PMD-CA are similar compared to DOTP, and superior to triethyl citrate and could therefore be considered as an effective bioplasticiser for enteric coating formulations in the pharmaceutical industry.
- Full Text:
- Date Issued: 2019
- Authors: Marx, Johannes Scheepers
- Date: 2019
- Subjects: Plasticisers
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/44629 , vital:38164
- Description: In recent years, much attention has been focused on research to replace petroleumbased commodity plastics, in a cost-effective manner, with biodegradable materials offering competitive mechanical properties. The use of natural and/or biodegradable plasticisers, with low toxicity and good compatibility with several plastics, resins, rubber and elastomers in substitution of conventional plasticisers, such as phthalates and other synthetic plasticisers attract the market along with the increasing worldwide trend towards the use of bio-polymers. The main research objective entailed the behaviour of the novel bio-plasticiser PMDcitronellal acetal (PMD-CA) and its comparison with other commercial bio-plasticiser, triethyl citrate (TEC) and a non-phthalate plasticiser bis(2-ethylhexyl) terephthalate (DOTP), on ethylcellulose (EC) films to evaluate whether it would be feasible to replace them with PMD-CA. The films were produced by a casting technique and were characterised by mechanical properties, thermoanalysis, Scanning Electron Microscopy, disintegration and Fourier-Transform Infrared (FT-IR) spectroscopy. The addition of any of the three plasticisers to EC film increased the flexibility of the films. The plasticisers PMD-CA and DOTP added to EC formed tougher films as compared to EC films containing TEC shown by the high % elongation at break, strain and displacement. Statistically, it was proved that PMD-CA and DOTP had a more significant effect on % elongation of EC films than TEC, postulated to be due to their similar molecular size and structure. Thermoanalytical studies conducted revealed that the thermal degradation process of EC films proceeded in three basic stages, namely dehydration, depolymerisation and pyrolytic decomposition. Thermoanalytical analysis showed that unplasticised EC films had a higher glass transition value compared to the films containing any of the plasticisers and that PMD-CA and DOTP are more effective plasticisers compared to TEC due to their lower glass transition temperatures. The presence of plasticisers in the polymer matrix did change the surface morphology of polymer films. The addition of hydroxypropyl methylcellulose (HPMC) to EC PMD-CA and EC DOTP films caused more significant globule-like bubbles which were not uniform in size on the surface of these films. Observations were made that the type of plasticiser coating with or without pore former influenced the disintegration properties of films. HPMC, as pore former, played a significant role in the drug release system matrix. EC PMD-CA and EC DOTP polymeric films controlled the disintegration of the films in the acidic and weakly acidic medium. EC and EC TEC films had less significant control on the disintegration rate of the acidic and weakly acidic disintegration media. FT-IR characterisation of the films revealed comparable peaks observed in all the polymer-plasticiser combinations and therefore it was concluded that chemical interactions did not exist between the polymers and plasticisers. Added excipients (plasticisers and pore formers) were found to be compatible with EC films. It was concluded within the scope of this research that EC films plasticised with PMDCA, DOTP or TEC outperformed film properties of those compared to unplasticised EC film. The plasticising properties of the novel bio-plasticiser PMD-CA are similar compared to DOTP, and superior to triethyl citrate and could therefore be considered as an effective bioplasticiser for enteric coating formulations in the pharmaceutical industry.
- Full Text:
- Date Issued: 2019
An evaluation of programming assistance tools to support the learning of IT programming: a case study in South African secondary schools
- Authors: Koorsse, Melisa
- Date: 2012
- Subjects: Computer science , Computer literacy , Computer programming
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10472 , http://hdl.handle.net/10948/d1010581 , Computer science , Computer literacy , Computer programming
- Description: Worldwide, there is a decline in interest in the computer science profession and in the subject at secondary school level. Novice programmers struggle to understand introductory programming concepts and this difficulty of learning to program is contributing to the lack of interest in the field of computer science. Information Technology (IT) learners in South African secondary schools are novice programmers, introduced to introductory programming concepts in the subject which also includes topics on hardware and system software, e-communication, social and ethical issues, spreadsheets and databases. The difficulties faced by IT learners are worsened by the lack of suitably qualified teachers, a saturated learning programme that allocates very little time to the understanding of complex programming concepts and limited class time where practical examples can be implemented with the support of the IT teacher. This research proposes that IT learners could be supported by a programming assistance tool (PAT). A PAT is a software program that can be used by novice programmers to learn how to program and/or improve their understanding of programming concepts. PATs use different techniques to assist novice programmers. The main objective of this research was to determine whether the use of a PAT impacted IT learners’ understanding of programming concepts and motivation towards programming. The literature study and feedback from IT learners and teachers were used to identify novice programming difficulties and IT learner programming difficulties, respectively. Selection criteria were derived from the programming difficulties identified. The selection criteria were grouped into three categories, namely, programming concepts, programming knowledge and programming skills. Existing PATs were evaluated using the selection criteria and three PATs, namely, RoboMind, Scratch and B#, were selected as suitable for use by IT learners. RoboMind was adapted in this research study, allowing it to support the Delphi programming language. The three PATs were evaluated by participating IT learners at four schools. The findings of this research provided no conclusive evidence that IT learners who used a PAT had a significantly better understanding of programming concepts and motivation towards programming than learners who did not use a PAT. IT learner feedback was used to identify the strengths and shortcomings of the three PATs and to provide recommendations for the development of PATs specifically to support IT learners. This research study has provided several theoretical and practical contributions, including the research design, selection criteria, adaptations to RoboMind and the evaluation of the three PATs. In addition, IT teachers and learners have been made aware of PATs and the support that can be provided by these PATs. IT teachers have also been provided with a means of selecting PATs applicable to the IT curriculum. All the research contributions have formed the basis for future work, such as improving and extending RoboMind’s functionality and support of programming concepts, the refinement of the selection criteria and, ultimately, the development of a new PAT, specifically designed to support IT learner understanding of programming concepts and motivation towards programming.
- Full Text:
- Date Issued: 2012
- Authors: Koorsse, Melisa
- Date: 2012
- Subjects: Computer science , Computer literacy , Computer programming
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:10472 , http://hdl.handle.net/10948/d1010581 , Computer science , Computer literacy , Computer programming
- Description: Worldwide, there is a decline in interest in the computer science profession and in the subject at secondary school level. Novice programmers struggle to understand introductory programming concepts and this difficulty of learning to program is contributing to the lack of interest in the field of computer science. Information Technology (IT) learners in South African secondary schools are novice programmers, introduced to introductory programming concepts in the subject which also includes topics on hardware and system software, e-communication, social and ethical issues, spreadsheets and databases. The difficulties faced by IT learners are worsened by the lack of suitably qualified teachers, a saturated learning programme that allocates very little time to the understanding of complex programming concepts and limited class time where practical examples can be implemented with the support of the IT teacher. This research proposes that IT learners could be supported by a programming assistance tool (PAT). A PAT is a software program that can be used by novice programmers to learn how to program and/or improve their understanding of programming concepts. PATs use different techniques to assist novice programmers. The main objective of this research was to determine whether the use of a PAT impacted IT learners’ understanding of programming concepts and motivation towards programming. The literature study and feedback from IT learners and teachers were used to identify novice programming difficulties and IT learner programming difficulties, respectively. Selection criteria were derived from the programming difficulties identified. The selection criteria were grouped into three categories, namely, programming concepts, programming knowledge and programming skills. Existing PATs were evaluated using the selection criteria and three PATs, namely, RoboMind, Scratch and B#, were selected as suitable for use by IT learners. RoboMind was adapted in this research study, allowing it to support the Delphi programming language. The three PATs were evaluated by participating IT learners at four schools. The findings of this research provided no conclusive evidence that IT learners who used a PAT had a significantly better understanding of programming concepts and motivation towards programming than learners who did not use a PAT. IT learner feedback was used to identify the strengths and shortcomings of the three PATs and to provide recommendations for the development of PATs specifically to support IT learners. This research study has provided several theoretical and practical contributions, including the research design, selection criteria, adaptations to RoboMind and the evaluation of the three PATs. In addition, IT teachers and learners have been made aware of PATs and the support that can be provided by these PATs. IT teachers have also been provided with a means of selecting PATs applicable to the IT curriculum. All the research contributions have formed the basis for future work, such as improving and extending RoboMind’s functionality and support of programming concepts, the refinement of the selection criteria and, ultimately, the development of a new PAT, specifically designed to support IT learner understanding of programming concepts and motivation towards programming.
- Full Text:
- Date Issued: 2012
An in vitro evaluation of anti-breast cancer activity of novel, heterocyclic aromatic compounds in combination with curcumin
- Authors: Pereira, Melanie Claire
- Date: 2017
- Subjects: Breast -- Cancer Heterocyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/20416 , vital:29284
- Description: Nearly two thirds of breast cancers are classified as estrogen receptor positive. Estrogen receptor (+) breast cancer is usually treated with anti-estrogen therapy, using Tamoxifen as the primary standard of treatment. Unfortunately, resistance to Tamoxifen is known to occur after 1 to 3 years of Tamoxifen therapy. For this reason, improved treatment strategies for ER (+) breast cancer are urgently needed. The general toxicity exerted by most anti-cancer drugs on proliferating cells, as well as some normal cells, restricts their therapeutic use. Novel cytotoxic agents developed with unique mechanisms of action have not been therapeutically suitable, since many of these compounds lack tumour selectivity. The adverse effects and the inefficacies of most chemotherapeutic therapies have motivated extensive investigations of alternatives. Numerous studies have demonstrated the advantages of using combination therapy with naturally-derived agents as an alternative, due to the higher therapeutic efficacy; with the added benefit of lower drug usage and reduction in drug-resistance development. An excellent example of a naturally derived and common dietary agent is curcumin, the active constituent of turmeric. Curcumin is known to modulate several signalling pathways in addition to displaying a diverse range of anti-tumour activities against a number of cancer cells. Several reports point to curcumin being beneficial if used in addition to chemotherapeutic drugs. In this study, synthetic aminonaphthoquinone derivatives (coded Rau 008, Rau 010, Rau 015 and Rau 018) were tested individually and in combination with curcumin for the potential as anti-breast cancer agents in different tumour cell lines. Notably, the aminonaphthoquinone class of compounds have shown potential as anti-cancer agents in various tumour cell lines. This study was thus aimed at screening the Rau compounds (and selected combinations with curcumin) for anti-cancer activity using a range of in vitro biological assays, and was not mechanistic in nature. The IC50 values of the individual and combined drugs were determined from dose-response curves using non-linear regression analyses. Synergistic, additive and antagonistic drug interactions were assessed using combination index and isobologram approaches. Based on these interactions, selected drug combinations were then further analysed for their potential anti-estrogenic, cytotoxic, anti-angiogenic and anti-metastatic effects against the ER(-) MDA-MB-231 and ER(+) MCF-7 breast cancer cell lines. The potential anti-cancer effects of the selected drug combinations on other estrogen-responsive models, such as the osteosarcoma (MG-63) and endometrial cancer (HEC-1A) cell lines, were also investigated. Overall, the findings of this study indicated that the sensitivity of the tumour cells to the various test compounds was significantly enhanced when combined with curcumin. For instance, in the presence of curcumin, Rau 008 or Rau 010 reduced the metastatic capability of ER(-) breast cancer cells significantly. The anti-proliferative effect of the Rau 015+curcumin combination was enhanced in ER(+) and ER(-) breast cancer, including oteosarcoma cells, while a combination of Rau 015 and curcumin induced a significant cytotoxic effect in ER(-) breast cancer and endometrial cancer-derived cells. A combination of Rau 018 and curcumin inhibited the proliferation of ER(+) breast cancer, and the combined effect was significantly more enhanced compared to individual treatment. A similar effect was noted in osteosarcoma-derived cells. Further, the Rau 018+curcumin combination exerted a marked cytotoxic and anti-angiogenic effect in ER(-) breast cancer, osteosarcoma and endometrial cancer in addition to inhibiting the attachment of ER(-) breast cancer cells to collagen. Notably, curcumin enhanced the anti-proliferative effect of Tamoxifen in breast cancer (MCF-7 and MDA-MB-231), osteosarcoma and endometrial cancer, and also induced a significant cytotoxic effect against ER(+) breast cancer and osteosarcoma, whilst also reducing the invasive potential of ER(-) breast cancer. A combination of 17β-estradiol and curcumin induced a marked anti-proliferative effect in ER(+) and ER(-) breast cancer, reduced the adhesion of ER(-) breast cancer to laminin, and elicited a significant cytotoxic and anti-angiogenic effect against endometrial cancer. Notably all the selected combinations (except Rau 018 and curcumin) inhibited bone mineralization. These findings point to the vital influence of curcumin in the responsiveness of ER(+) and ER(-) tumours towards the relative test agents. Further, among the Rau+curcumin combinations tested in this study, the anti-cancer activity of Rau 015+curcumin and Rau 018+curcumin appeared to be the most effective in the different cell lines tested. Nonetheless, it appears that a combination of 30 μM Rau 018 with 100 μM curcumin may be more promising as an anti-breast cancer agent against ER(+) and perhaps triple negative breast cancer, and warrants further investigation.
- Full Text:
- Date Issued: 2017
- Authors: Pereira, Melanie Claire
- Date: 2017
- Subjects: Breast -- Cancer Heterocyclic compounds
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/20416 , vital:29284
- Description: Nearly two thirds of breast cancers are classified as estrogen receptor positive. Estrogen receptor (+) breast cancer is usually treated with anti-estrogen therapy, using Tamoxifen as the primary standard of treatment. Unfortunately, resistance to Tamoxifen is known to occur after 1 to 3 years of Tamoxifen therapy. For this reason, improved treatment strategies for ER (+) breast cancer are urgently needed. The general toxicity exerted by most anti-cancer drugs on proliferating cells, as well as some normal cells, restricts their therapeutic use. Novel cytotoxic agents developed with unique mechanisms of action have not been therapeutically suitable, since many of these compounds lack tumour selectivity. The adverse effects and the inefficacies of most chemotherapeutic therapies have motivated extensive investigations of alternatives. Numerous studies have demonstrated the advantages of using combination therapy with naturally-derived agents as an alternative, due to the higher therapeutic efficacy; with the added benefit of lower drug usage and reduction in drug-resistance development. An excellent example of a naturally derived and common dietary agent is curcumin, the active constituent of turmeric. Curcumin is known to modulate several signalling pathways in addition to displaying a diverse range of anti-tumour activities against a number of cancer cells. Several reports point to curcumin being beneficial if used in addition to chemotherapeutic drugs. In this study, synthetic aminonaphthoquinone derivatives (coded Rau 008, Rau 010, Rau 015 and Rau 018) were tested individually and in combination with curcumin for the potential as anti-breast cancer agents in different tumour cell lines. Notably, the aminonaphthoquinone class of compounds have shown potential as anti-cancer agents in various tumour cell lines. This study was thus aimed at screening the Rau compounds (and selected combinations with curcumin) for anti-cancer activity using a range of in vitro biological assays, and was not mechanistic in nature. The IC50 values of the individual and combined drugs were determined from dose-response curves using non-linear regression analyses. Synergistic, additive and antagonistic drug interactions were assessed using combination index and isobologram approaches. Based on these interactions, selected drug combinations were then further analysed for their potential anti-estrogenic, cytotoxic, anti-angiogenic and anti-metastatic effects against the ER(-) MDA-MB-231 and ER(+) MCF-7 breast cancer cell lines. The potential anti-cancer effects of the selected drug combinations on other estrogen-responsive models, such as the osteosarcoma (MG-63) and endometrial cancer (HEC-1A) cell lines, were also investigated. Overall, the findings of this study indicated that the sensitivity of the tumour cells to the various test compounds was significantly enhanced when combined with curcumin. For instance, in the presence of curcumin, Rau 008 or Rau 010 reduced the metastatic capability of ER(-) breast cancer cells significantly. The anti-proliferative effect of the Rau 015+curcumin combination was enhanced in ER(+) and ER(-) breast cancer, including oteosarcoma cells, while a combination of Rau 015 and curcumin induced a significant cytotoxic effect in ER(-) breast cancer and endometrial cancer-derived cells. A combination of Rau 018 and curcumin inhibited the proliferation of ER(+) breast cancer, and the combined effect was significantly more enhanced compared to individual treatment. A similar effect was noted in osteosarcoma-derived cells. Further, the Rau 018+curcumin combination exerted a marked cytotoxic and anti-angiogenic effect in ER(-) breast cancer, osteosarcoma and endometrial cancer in addition to inhibiting the attachment of ER(-) breast cancer cells to collagen. Notably, curcumin enhanced the anti-proliferative effect of Tamoxifen in breast cancer (MCF-7 and MDA-MB-231), osteosarcoma and endometrial cancer, and also induced a significant cytotoxic effect against ER(+) breast cancer and osteosarcoma, whilst also reducing the invasive potential of ER(-) breast cancer. A combination of 17β-estradiol and curcumin induced a marked anti-proliferative effect in ER(+) and ER(-) breast cancer, reduced the adhesion of ER(-) breast cancer to laminin, and elicited a significant cytotoxic and anti-angiogenic effect against endometrial cancer. Notably all the selected combinations (except Rau 018 and curcumin) inhibited bone mineralization. These findings point to the vital influence of curcumin in the responsiveness of ER(+) and ER(-) tumours towards the relative test agents. Further, among the Rau+curcumin combinations tested in this study, the anti-cancer activity of Rau 015+curcumin and Rau 018+curcumin appeared to be the most effective in the different cell lines tested. Nonetheless, it appears that a combination of 30 μM Rau 018 with 100 μM curcumin may be more promising as an anti-breast cancer agent against ER(+) and perhaps triple negative breast cancer, and warrants further investigation.
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- Date Issued: 2017