Interrogating the specific challenges of teaching play texts in heterogeneous classrooms in the Eastern Cape
- Authors: Hayes, Nicola
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:6022 , http://hdl.handle.net/10962/d1021251
- Description: This study is an autoethnographic reflection, rooted in Action Research based on my teaching experience in a multicultural high school environment in the Eastern Cape, South Africa. It is an analysis, in particular, of teaching play texts in two classes, Dramatic Arts and English Home Language, at matric level. A combination of discourse analysis and autoethnography formed the theoretical basis for the interpretation of data drawn from lesson transcripts, group interviews, learners’ reflections and my own journalled reflections. This analysis has formed the foundation for a deeper reflection on culture, the colonist within, and the colonialism embedded with in my teaching, and in the education system more broadly. At a practical level, I suggest embracing student-led and co-led discussions of literature, as advocated by Mayer (2012), as well as transcultural readings (Keating, 2007), and Drama activities, as ideals in the teaching of play texts. These techniques are designed to encourage learners to develop intellectual authority as well as allowing them the space to enter discussions around culturally sensitive topics, while minimising the teacher’s hierarchical, dominant position. I also argue for the importance of making culture an overt topic of conversation. White English-speaking South African culture, in particular has been prone to “invisibility” and, through this, an unspoken normative position, particularly in multicultural school environments. I challenge myself and others to engage in ongoing efforts to articulate our particular perception of our cultures, dynamic and diverse though they may be.
- Full Text:
- Date Issued: 2016
- Authors: Hayes, Nicola
- Date: 2016
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:6022 , http://hdl.handle.net/10962/d1021251
- Description: This study is an autoethnographic reflection, rooted in Action Research based on my teaching experience in a multicultural high school environment in the Eastern Cape, South Africa. It is an analysis, in particular, of teaching play texts in two classes, Dramatic Arts and English Home Language, at matric level. A combination of discourse analysis and autoethnography formed the theoretical basis for the interpretation of data drawn from lesson transcripts, group interviews, learners’ reflections and my own journalled reflections. This analysis has formed the foundation for a deeper reflection on culture, the colonist within, and the colonialism embedded with in my teaching, and in the education system more broadly. At a practical level, I suggest embracing student-led and co-led discussions of literature, as advocated by Mayer (2012), as well as transcultural readings (Keating, 2007), and Drama activities, as ideals in the teaching of play texts. These techniques are designed to encourage learners to develop intellectual authority as well as allowing them the space to enter discussions around culturally sensitive topics, while minimising the teacher’s hierarchical, dominant position. I also argue for the importance of making culture an overt topic of conversation. White English-speaking South African culture, in particular has been prone to “invisibility” and, through this, an unspoken normative position, particularly in multicultural school environments. I challenge myself and others to engage in ongoing efforts to articulate our particular perception of our cultures, dynamic and diverse though they may be.
- Full Text:
- Date Issued: 2016
Towards large scale software based network routing simulation
- Authors: Herbert, Alan
- Date: 2015
- Subjects: Routers (Computer networks) , Computer software , Linux
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4709 , http://hdl.handle.net/10962/d1017931
- Description: Software based routing simulators suffer from large simulation host requirements and are prone to slow downs because of resource limitations, as well as context switching due to user space to kernel space requests. Furthermore, hardware based simulations do not scale with the passing of time as their available resources are set at the time of manufacture. This research aims to provide a software based, scalable solution to network simulation. It aims to achieve this by a Linux kernel-based solution, through insertion of a custom kernel module. This will reduce the number of context switches by eliminating the user space context requirement, and serve to be highly compatible with any host that can run the Linux kernel. Through careful consideration in data structure choice and software component design, this routing simulator achieved results of over 7 Gbps of throughput over multiple simulated node hops on consumer hardware. Alongside this throughput, this routing simulator also brings to light scalability and the ability to instantiate and simulate networks in excess of 1 million routing nodes within 1 GB of system memory
- Full Text:
- Date Issued: 2015
- Authors: Herbert, Alan
- Date: 2015
- Subjects: Routers (Computer networks) , Computer software , Linux
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4709 , http://hdl.handle.net/10962/d1017931
- Description: Software based routing simulators suffer from large simulation host requirements and are prone to slow downs because of resource limitations, as well as context switching due to user space to kernel space requests. Furthermore, hardware based simulations do not scale with the passing of time as their available resources are set at the time of manufacture. This research aims to provide a software based, scalable solution to network simulation. It aims to achieve this by a Linux kernel-based solution, through insertion of a custom kernel module. This will reduce the number of context switches by eliminating the user space context requirement, and serve to be highly compatible with any host that can run the Linux kernel. Through careful consideration in data structure choice and software component design, this routing simulator achieved results of over 7 Gbps of throughput over multiple simulated node hops on consumer hardware. Alongside this throughput, this routing simulator also brings to light scalability and the ability to instantiate and simulate networks in excess of 1 million routing nodes within 1 GB of system memory
- Full Text:
- Date Issued: 2015
The attitudes and perceptions of secondary school pupils in Transkei towards geography: a case study of the Butterworth district
- Authors: Sarpong, Emmanuel
- Date: 1992
- Subjects: Students, Black -- South Africa -- Attitudes Geography -- South Africa -- Transkei -- Study and teaching (Secondary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1425 , http://hdl.handle.net/10962/d1003306
- Description: Considerable attention has in recent times been given to the attitudes of secondary school pupils towards Geography among black schools in South Africa. Many reasons account for this. It is partly because of the poor results and falling numbers of pupils in the discipline. Concern has also been expressed on the relevance of the Geography syllabus to the black pupils. Evidence suggests that these problems are evident in Transkei. The need therefore exists to assess pupils' attitudes towards Geography in Transkei. Arising from this background, this study sets out to assess the attitudes of secondary school pupils in Transkei towards Geography. Two hundred and thirty four pupils from eight urban and rural secondary schools in the Butterworth District of the Republic of Transkei were used in the study. Attitudes were measured in terms of "interest in Geography", "desire to study the discipline", "commitment to Geography" and the perceived relevance of the discipline. Through the use of techniques such as percentages, chi-square and principal component analysis - among others - for the analysis of the data, the following information emerged from the study: (1) Geography is generally perceived as being worthy of study; (2) Differences in responses were noted to result from a complex of factors which were grouped into home environmental factors and school environmental ones. (3) The major factor influencing attitudes towards Geography was noted to be home environmental conditions.In general pupils from lower income families expressed more positive views about the worth of Geography than those from the upper income families. From the above findings, it has been proposed that teachers and educational planners need to be made aware of these findings as they are important for classroom practice. It has also been recommended that there is a need to improve certain school practices such as taking pupils on Geography excursions more often as factors such as this were shown to improve pupils' attitudes towards the discipline.
- Full Text:
- Date Issued: 1992
- Authors: Sarpong, Emmanuel
- Date: 1992
- Subjects: Students, Black -- South Africa -- Attitudes Geography -- South Africa -- Transkei -- Study and teaching (Secondary)
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1425 , http://hdl.handle.net/10962/d1003306
- Description: Considerable attention has in recent times been given to the attitudes of secondary school pupils towards Geography among black schools in South Africa. Many reasons account for this. It is partly because of the poor results and falling numbers of pupils in the discipline. Concern has also been expressed on the relevance of the Geography syllabus to the black pupils. Evidence suggests that these problems are evident in Transkei. The need therefore exists to assess pupils' attitudes towards Geography in Transkei. Arising from this background, this study sets out to assess the attitudes of secondary school pupils in Transkei towards Geography. Two hundred and thirty four pupils from eight urban and rural secondary schools in the Butterworth District of the Republic of Transkei were used in the study. Attitudes were measured in terms of "interest in Geography", "desire to study the discipline", "commitment to Geography" and the perceived relevance of the discipline. Through the use of techniques such as percentages, chi-square and principal component analysis - among others - for the analysis of the data, the following information emerged from the study: (1) Geography is generally perceived as being worthy of study; (2) Differences in responses were noted to result from a complex of factors which were grouped into home environmental factors and school environmental ones. (3) The major factor influencing attitudes towards Geography was noted to be home environmental conditions.In general pupils from lower income families expressed more positive views about the worth of Geography than those from the upper income families. From the above findings, it has been proposed that teachers and educational planners need to be made aware of these findings as they are important for classroom practice. It has also been recommended that there is a need to improve certain school practices such as taking pupils on Geography excursions more often as factors such as this were shown to improve pupils' attitudes towards the discipline.
- Full Text:
- Date Issued: 1992
On the occasion of Professor Brommert's retirement
- Authors: Henderson, Derek Scott
- Date: 1986-09-18
- Language: English
- Type: Text
- Identifier: vital:7532 , http://hdl.handle.net/10962/d1018409
- Full Text:
- Date Issued: 1986-09-18
- Authors: Henderson, Derek Scott
- Date: 1986-09-18
- Language: English
- Type: Text
- Identifier: vital:7532 , http://hdl.handle.net/10962/d1018409
- Full Text:
- Date Issued: 1986-09-18
Exploring the correlation between language medium and academic achievement: a comparative study of the language of learning and teaching (LoLT) and mathematics results in the 2010 Grade 12 National Senior Certificate examinations in the Eastern Cape
- Mbude-Shale, Beryl Ntombizanele
- Authors: Mbude-Shale, Beryl Ntombizanele
- Date: 2013
- Subjects: Academic achievement -- Research -- South Africa -- Eastern Cape Language and education -- Research -- South Africa -- Eastern Cape Language policy -- South Africa -- Eastern Cape Mathematics -- Study and teaching (Elementary) -- South Africa -- Eastern Cape Education, Secondary -- South Africa -- Eastern Cape Matric Learners Language planning Mathematics Policies Academic performance Mother-tongue
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3559 , http://hdl.handle.net/10962/d1001863
- Description: In 2009, of the 68,129 learners who wrote Matric, only 34,731 learners passed. In 2010, there was an increase in the provincial pass rate causing much excitement across the board. The reality was that of the 64,090 learners who wrote, only 37,345 learners passed. In 2010, a result below 50% was recorded for Mathematics and Physical Science nationally (DBE; 2011). Despite efforts by the Education Department to support MSTE; establishing Mathematics and Science schools, NGOs and HEIs giving extra Mathematics and Science support to students and teachers, the offering of Saturday classes and incubation camps, we still get minimal return on investment. This thesis analyses these results against the backdrop of language planning theory, particularly language-in-education policies, pre and post-apartheid. The correlation between language medium and academic performance in language (LoLT) and Mathematics of Grade 12 learners is explored. Worldwide the issue of low achievement in Mathematics by ESL students is of great concern (Cuevas, 1984). The 2004 Systemic Evaluation sample of learners was in Grade 6 then; in 2010 they wrote Grade 12. The purpose of the systemic evaluation was to provide an insight into the levels of learner performance in Maths, Natural Science and LoLT in Grade 6 (IPSER, 2006). A major finding of the IPSER was that language was an important factor related to learner achievement. A major disparity was observed in this research, that although the Eastern Cape performed below the national average in the three subjects evaluated, the learners for whom LoLT was the same as their home language obtained scores that were significantly higher than those whose home language was different from the LoLT. The provincial average for Mathematics was 23.40% compared to the national average of 27.80%. For LoLT the province scored 30.16 against the national score of 38.03%. Of interest in this study is a juxtaposition of the Matric results of this same group of learners in 2010 and see whether issues that came up then are still significant in mitigating achievement in Mathematics and Language (LoLT). Some research studies have been conducted in South Africa (Adler, 1998; Setati, 1996-2002; Moloi, 2006) identifying the vital role language plays in learning Mathematics, especially for English L2 learners. Building on research and findings of academics such as the late Alexander, Ramani, Joseph, Hendricks, Heugh, Dalvit, Webb and Murray, this thesis suggests that a mother-tongue-based-bilingual approach to education should be adopted as a matter of urgency
- Full Text:
- Date Issued: 2013
- Authors: Mbude-Shale, Beryl Ntombizanele
- Date: 2013
- Subjects: Academic achievement -- Research -- South Africa -- Eastern Cape Language and education -- Research -- South Africa -- Eastern Cape Language policy -- South Africa -- Eastern Cape Mathematics -- Study and teaching (Elementary) -- South Africa -- Eastern Cape Education, Secondary -- South Africa -- Eastern Cape Matric Learners Language planning Mathematics Policies Academic performance Mother-tongue
- Language: English
- Type: text , Thesis , Masters , MA
- Identifier: vital:3559 , http://hdl.handle.net/10962/d1001863
- Description: In 2009, of the 68,129 learners who wrote Matric, only 34,731 learners passed. In 2010, there was an increase in the provincial pass rate causing much excitement across the board. The reality was that of the 64,090 learners who wrote, only 37,345 learners passed. In 2010, a result below 50% was recorded for Mathematics and Physical Science nationally (DBE; 2011). Despite efforts by the Education Department to support MSTE; establishing Mathematics and Science schools, NGOs and HEIs giving extra Mathematics and Science support to students and teachers, the offering of Saturday classes and incubation camps, we still get minimal return on investment. This thesis analyses these results against the backdrop of language planning theory, particularly language-in-education policies, pre and post-apartheid. The correlation between language medium and academic performance in language (LoLT) and Mathematics of Grade 12 learners is explored. Worldwide the issue of low achievement in Mathematics by ESL students is of great concern (Cuevas, 1984). The 2004 Systemic Evaluation sample of learners was in Grade 6 then; in 2010 they wrote Grade 12. The purpose of the systemic evaluation was to provide an insight into the levels of learner performance in Maths, Natural Science and LoLT in Grade 6 (IPSER, 2006). A major finding of the IPSER was that language was an important factor related to learner achievement. A major disparity was observed in this research, that although the Eastern Cape performed below the national average in the three subjects evaluated, the learners for whom LoLT was the same as their home language obtained scores that were significantly higher than those whose home language was different from the LoLT. The provincial average for Mathematics was 23.40% compared to the national average of 27.80%. For LoLT the province scored 30.16 against the national score of 38.03%. Of interest in this study is a juxtaposition of the Matric results of this same group of learners in 2010 and see whether issues that came up then are still significant in mitigating achievement in Mathematics and Language (LoLT). Some research studies have been conducted in South Africa (Adler, 1998; Setati, 1996-2002; Moloi, 2006) identifying the vital role language plays in learning Mathematics, especially for English L2 learners. Building on research and findings of academics such as the late Alexander, Ramani, Joseph, Hendricks, Heugh, Dalvit, Webb and Murray, this thesis suggests that a mother-tongue-based-bilingual approach to education should be adopted as a matter of urgency
- Full Text:
- Date Issued: 2013
A critical evaluation of inter-jurisdictional rules in the South African value-added tax system
- Authors: Schneider, Ferdinand Dirk
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7971 , vital:21329
- Description: This study analysed the current inter-jurisdictional rules in the South African Value-Added Tax (VAT) system, identified shortcomings, and proposed legislative amendments or additions to address these shortcomings. The research was conducted within an interpretative post positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the theoretical basis of a good tax system and the theory underpinning indirect and consumption taxation. The literature review also included an in-depth analysis of the South African VAT system and its treatment of resident and non-resident businesses with a South African physical or economic reach, and its treatment of local and cross-border transactions, including imported services. The literature review also considered the international VAT treatment of these transactions. To obtain a wider range of expert opinions regarding shortcomings in inter-jurisdictional rules in the South African VAT system, data was collected through structured interviews with South African and global VAT and indirect tax experts, using a questionnaire that was specifically designed for this purpose. This study proposed amendments and additions to the VAT Act, dealing with the VAT registration of non-resident suppliers; addressing various issues relating to the interjurisdictional VAT rate; proposing measures in connection with imported services; and legislating the intention of the legislator to tax final utilisation or consumption. The study finally recommended the introduction of a general place of supply rule linked to residency; specific place of supply rules for electronic, broadcasting, and telecommunication services; and zero rating provisions for electronic, broadcasting, and telecommunication services provided to non-resident suppliers by resident suppliers for services initiated outside South Africa.
- Full Text:
- Date Issued: 2017
- Authors: Schneider, Ferdinand Dirk
- Date: 2017
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/7971 , vital:21329
- Description: This study analysed the current inter-jurisdictional rules in the South African Value-Added Tax (VAT) system, identified shortcomings, and proposed legislative amendments or additions to address these shortcomings. The research was conducted within an interpretative post positivism paradigm, applied a qualitative research methodology, and a doctrinal research method. A detailed review of the literature was conducted to establish the theoretical basis of a good tax system and the theory underpinning indirect and consumption taxation. The literature review also included an in-depth analysis of the South African VAT system and its treatment of resident and non-resident businesses with a South African physical or economic reach, and its treatment of local and cross-border transactions, including imported services. The literature review also considered the international VAT treatment of these transactions. To obtain a wider range of expert opinions regarding shortcomings in inter-jurisdictional rules in the South African VAT system, data was collected through structured interviews with South African and global VAT and indirect tax experts, using a questionnaire that was specifically designed for this purpose. This study proposed amendments and additions to the VAT Act, dealing with the VAT registration of non-resident suppliers; addressing various issues relating to the interjurisdictional VAT rate; proposing measures in connection with imported services; and legislating the intention of the legislator to tax final utilisation or consumption. The study finally recommended the introduction of a general place of supply rule linked to residency; specific place of supply rules for electronic, broadcasting, and telecommunication services; and zero rating provisions for electronic, broadcasting, and telecommunication services provided to non-resident suppliers by resident suppliers for services initiated outside South Africa.
- Full Text:
- Date Issued: 2017
A study of petrol and diesel fuel blends with special reference to their thermodynamic properties and phase equilibria
- Authors: Heyward, Caroline
- Date: 1986
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21167 , http://hdl.handle.net/10962/6695
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols. Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application.
- Full Text:
- Date Issued: 1986
- Authors: Heyward, Caroline
- Date: 1986
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:21167 , http://hdl.handle.net/10962/6695
- Description: The ternary phase behaviour of the n-heptane-l-propanol-water system was studied and compared with the theoretical prediction based on the UNIQUAC model for non-electrolyte solutions. The results showed that this model adequately approximated experimental studies. The excess enthalpies and excess volumes for several binary mixtures were determined. The excess enthalpies were measured using a LKB flow microcalorimeter and the excess -volumes determined using a PAAR densitometer. The study showed that no significant enthalpy or volume changes occurred when petrol/n-heptane were mixed with alcohols. Ternary phase diagrams, including tie lines have been determined for a number of petrol-alcohol-water systems (including the Sasol blend of alcohols). The tie line results show that the concentration of water in the water-rich layer is strongly dependent on the type of alcohol used. The Sasol alcohol blended with petrol resulted in a high water concentration in the water-rich layer which forms on phase separation. This is believed to contribute significantly to the corrosion problems experienced by motorists using the Sasol blended fuel on the Witwatersrand. The effect of temperature on several of these blends was included in the study. Diesel-alcohol blends and the co-solvent properties of ethyl acetate investigated. Ethyl acetate ensures miscibility at low concentrations for diesel-ethanol blends. Octyl nitrate and two cetane improvers from AECI were assessed in terms of their ability to restore cetane rating of blended diesel fuel to that of pure diesel fuel. The results indicated that all three samples were successful in this application.
- Full Text:
- Date Issued: 1986
Enactment of hands-on practical activities through using easily accessible resources in a Grade 10 Physical Science classroom
- Authors: Ndevahoma, Martha Kashike
- Date: 2020
- Subjects: Physical science -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/110229 , vital:33251
- Description: The Namibian National Subject Policy Guide for Physical Science Grade 8-12 (MoE, 2010) indicates that science teachers should be creative and innovative in producing their own teaching and learning support materials that are linked to practice. Practical activities play a major role in the learning of science. Due to the lack of science laboratory equipment, however, minimal practical activities are done in some schools especially under-resourced disadvantaged schools. It is against this background that this case study investigated the possibilities and challenges associated with the use of easily accessible resources to carry out hands-on practical activities. Underpinned by an interpretive paradigm, this study used a mixed-method approach by generating both quantitative and qualitative data. It was carried out in the Otjozondjupa region in Namibia at Wato Secondary School (pseudonym). It was conducted with a Grade 10 Physical Science class consisting of 30 learners. To generate data, questionnaires, focus group interviews, lesson observations, stimulated recall interviews, as well as learners’ journal reflections were used. Conceptions, dispositions, interest and sense-making were used as conceptual lenses while Vygotsky’s social constructivism was the theoretical framework that informed this study. Quantitative data were analysed using the conceptual lenses and were subsequently presented in tables and graphs. That is, a deductive approach to analysis was used. On the other hand, a thematic approach was used to analyse the qualitative data. That is, qualitative data were inductively analysed to come up with sub-themes and themes. The findings from this study revealed significant shifts in learners’ conceptions, dispositions and interest towards science after the use of easily accessible resources to do hands-on practical activities. Similarly, learners’ sense-making of science concepts improved. This study thus recommends that science teachers should, where possible, make use of easily accessible resources to carry out hands-on practical activities during their science lessons. During such hands-on practicals, however, emphasis should be on the development of scientific concepts.
- Full Text:
- Date Issued: 2020
- Authors: Ndevahoma, Martha Kashike
- Date: 2020
- Subjects: Physical science -- Study and teaching (Secondary) -- Namibia
- Language: English
- Type: text , Thesis , Masters , MEd
- Identifier: http://hdl.handle.net/10962/110229 , vital:33251
- Description: The Namibian National Subject Policy Guide for Physical Science Grade 8-12 (MoE, 2010) indicates that science teachers should be creative and innovative in producing their own teaching and learning support materials that are linked to practice. Practical activities play a major role in the learning of science. Due to the lack of science laboratory equipment, however, minimal practical activities are done in some schools especially under-resourced disadvantaged schools. It is against this background that this case study investigated the possibilities and challenges associated with the use of easily accessible resources to carry out hands-on practical activities. Underpinned by an interpretive paradigm, this study used a mixed-method approach by generating both quantitative and qualitative data. It was carried out in the Otjozondjupa region in Namibia at Wato Secondary School (pseudonym). It was conducted with a Grade 10 Physical Science class consisting of 30 learners. To generate data, questionnaires, focus group interviews, lesson observations, stimulated recall interviews, as well as learners’ journal reflections were used. Conceptions, dispositions, interest and sense-making were used as conceptual lenses while Vygotsky’s social constructivism was the theoretical framework that informed this study. Quantitative data were analysed using the conceptual lenses and were subsequently presented in tables and graphs. That is, a deductive approach to analysis was used. On the other hand, a thematic approach was used to analyse the qualitative data. That is, qualitative data were inductively analysed to come up with sub-themes and themes. The findings from this study revealed significant shifts in learners’ conceptions, dispositions and interest towards science after the use of easily accessible resources to do hands-on practical activities. Similarly, learners’ sense-making of science concepts improved. This study thus recommends that science teachers should, where possible, make use of easily accessible resources to carry out hands-on practical activities during their science lessons. During such hands-on practicals, however, emphasis should be on the development of scientific concepts.
- Full Text:
- Date Issued: 2020
The incorporation of GeoGebra as a visualisation tool to teach calculus in teacher education institutions: the Zambian case
- Authors: Kangwa, Lemmy
- Date: 2022-10-14
- Subjects: GeoGebra , Calculus Study and teaching (Secondary) Zambia , Visual learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405470 , vital:70174 , DOI
- Description: This qualitative case study investigated teacher educators’ (lecturers) use of the dynamic mathematics software, GeoGebra, to teach calculus in three teacher education institutions (TEIs) in Zambia. Visualisation, a key characteristic of GeoGebra, is increasingly gaining recognition of playing a critical role in mathematics teaching and learning, especially in problem solving tasks. It is considered a powerful didactical tool for students to construct mental and physical representations that can enhance conceptual understanding of mathematics. GeoGebra is a visualisation tool that can be used for problem-oriented teaching and foster mathematical experiments and discoveries. GeoGebra’s inherent visualisation characteristics align well with the teaching of calculus, the mathematical domain of this study. The study (whose research methodology was underpinned by the interpretive paradigm) was undertaken with a broader goal of designing and implementing GeoGebra applets and instructional materials on various calculus topics. The study is located within the “Teaching and Learning Mathematics with GeoGebra (TLMG) project” – a project that involves mathematics teachers and lecturers in Zambia. The case in this study is the six mathematics lecturers who co-designed and used GeoGebra applets to teach derivatives and integrals to pre-service mathematics teachers in TEIs. The unit of analysis therefore is the six lecturers’ use of GeoGebra as a visualisation tool to teach calculus to enhance conceptual understanding, their perceptions and experiences of using GeoGebra and the enabling and constraining factors of using GeoGebra to teach and learn mathematics. The data for the study were video recordings of observations and interviews of lecturers. The data was analysed thematically and was guided and informed by an analytical framework adopted from the theory of constructivism – the umbrella theoretical framework of this study – and the models of Technological Pedagogical Content Knowledge (TPACK), and the Technology Acceptance Model (TAM). A detailed analysis of the lecturers’ interactions with the applets enabled me to gain insights into the participants’ experiences and perceptions of GeoGebra applets in the teaching and learning process. The findings of the study revealed that the visualisation characteristics of GeoGebra generally enhanced the conceptual understanding of calculus. It also revealed that adequate training, coupled with sufficient knowledge of the subject matter in calculus, were necessary for lecturers to use GeoGebra effectively, and that the lack of resources and expertise were major hindrances in the use of GeoGebra to teach mathematics in TEIs. It also revealed that there is a need to equip GeoGebra with other features that would make it more versatile, and suggested a teaching approach that would complement the use of conventional methods and GeoGebra to provide a link between abstract and concrete concepts of calculus. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-10-14
- Authors: Kangwa, Lemmy
- Date: 2022-10-14
- Subjects: GeoGebra , Calculus Study and teaching (Secondary) Zambia , Visual learning
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/405470 , vital:70174 , DOI
- Description: This qualitative case study investigated teacher educators’ (lecturers) use of the dynamic mathematics software, GeoGebra, to teach calculus in three teacher education institutions (TEIs) in Zambia. Visualisation, a key characteristic of GeoGebra, is increasingly gaining recognition of playing a critical role in mathematics teaching and learning, especially in problem solving tasks. It is considered a powerful didactical tool for students to construct mental and physical representations that can enhance conceptual understanding of mathematics. GeoGebra is a visualisation tool that can be used for problem-oriented teaching and foster mathematical experiments and discoveries. GeoGebra’s inherent visualisation characteristics align well with the teaching of calculus, the mathematical domain of this study. The study (whose research methodology was underpinned by the interpretive paradigm) was undertaken with a broader goal of designing and implementing GeoGebra applets and instructional materials on various calculus topics. The study is located within the “Teaching and Learning Mathematics with GeoGebra (TLMG) project” – a project that involves mathematics teachers and lecturers in Zambia. The case in this study is the six mathematics lecturers who co-designed and used GeoGebra applets to teach derivatives and integrals to pre-service mathematics teachers in TEIs. The unit of analysis therefore is the six lecturers’ use of GeoGebra as a visualisation tool to teach calculus to enhance conceptual understanding, their perceptions and experiences of using GeoGebra and the enabling and constraining factors of using GeoGebra to teach and learn mathematics. The data for the study were video recordings of observations and interviews of lecturers. The data was analysed thematically and was guided and informed by an analytical framework adopted from the theory of constructivism – the umbrella theoretical framework of this study – and the models of Technological Pedagogical Content Knowledge (TPACK), and the Technology Acceptance Model (TAM). A detailed analysis of the lecturers’ interactions with the applets enabled me to gain insights into the participants’ experiences and perceptions of GeoGebra applets in the teaching and learning process. The findings of the study revealed that the visualisation characteristics of GeoGebra generally enhanced the conceptual understanding of calculus. It also revealed that adequate training, coupled with sufficient knowledge of the subject matter in calculus, were necessary for lecturers to use GeoGebra effectively, and that the lack of resources and expertise were major hindrances in the use of GeoGebra to teach mathematics in TEIs. It also revealed that there is a need to equip GeoGebra with other features that would make it more versatile, and suggested a teaching approach that would complement the use of conventional methods and GeoGebra to provide a link between abstract and concrete concepts of calculus. , Thesis (PhD) -- Faculty of Education, Education, 2022
- Full Text:
- Date Issued: 2022-10-14
St Mary's Diocesan School for Girls, Pretoria, prize-giving
- Authors: Henderson, Derek Scott
- Date: 1986-11-27
- Language: English
- Type: Text
- Identifier: vital:7548 , http://hdl.handle.net/10962/d1018425
- Full Text:
- Date Issued: 1986-11-27
- Authors: Henderson, Derek Scott
- Date: 1986-11-27
- Language: English
- Type: Text
- Identifier: vital:7548 , http://hdl.handle.net/10962/d1018425
- Full Text:
- Date Issued: 1986-11-27
Representation and use of indigenous heritage constructs : implications for the quality and relevance of heritage education in post colonial southern Africa
- Authors: Zazu, Cryton
- Date: 2013
- Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
- Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
- Full Text:
- Date Issued: 2013
- Authors: Zazu, Cryton
- Date: 2013
- Subjects: Albany Museum (Grahamstown, South Africa) Cultural property -- Conservation and restoration -- Research -- Africa, Southern Great Zimbabwe (Extinct city) Indigenous peoples -- Material culture -- Africa, Southern Anthropological museums and collections -- Management -- Research -- Africa, Southern Cultural property -- Management -- Research Ethnoscience -- Study and teaching -- Africa, Southern
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:1407 , http://hdl.handle.net/10962/d1002015
- Description: This study explores representation and use of indigenous heritage constructs with a view to identifying implications thereof for the quality and relevance of heritage education practices in post colonial southern Africa. Framed within a critical hermeneutic research paradigm under-laboured by critical realist ontology, the study was conducted using a multiple case study research design. The data collection protocol was three-phased, starting with a process of contextual profiling, within which insights were gained into discourses shaping the constitution and orientation of heritage education practices at the Albany Museum in South Africa, the Great Zimbabwe Monument in Zimbabwe and the Supa Ngwao Museum in Botswana. The second phase of data collection entailed modelling workshops in which educators engaged in discussion around the status of heritage education in post apartheid South Africa. This highlighted, through modelled lessons, some of the tensions, challenges and implications for working with notions of social transformation and inclusivity in heritage education. The third phase of data collection involved in-depth interviews. Twelve purposively selected research participants were interviewed between 2010 and 2011. Data generated across the study was processed and subjected to different levels of critical discourse analysis. Besides noting how heritage education in post colonial southern Africa is poorly framed and under-researched, this study revealed that current forms of representing indigenous heritage constructs are influenced more by socio-political discourses than the need to protect and conserve local heritage resources. The study also noted that the observed heritage education practices are oriented more towards addressing issues related to marginalisation and alienation of indigenous cultures and practices, than enhancing learners’ agency to manage and utilise local heritage resources in a more sustainable ways. Based on these findings the study recommends re-positioning heritage education within the framework of Education for Sustainable Development (ESD). ESD acknowledges both issues of social justice and the dialectical interplay between nature and culture; as such, it may allow for representation and use of indigenous heritage constructs in ways that expand current political orientations to include sustainability as an additional objective of heritage education. Given that little research focusing on heritage education has been undertaken within southern Africa, the findings of this study provide a basis upon which future research may emerge.
- Full Text:
- Date Issued: 2013
Curriculum outcomes, teaching practices and learner competencies in isiXhosa in three Grahamstown schools
- Authors: Fobe, Mila Pamella
- Date: 2014
- Subjects: Xhosa language -- Study and teaching (Primary) -- South Africa -- Grahamstown Xhosa language -- Study and teaching (Secondary) -- South Africa -- Grahamstown Language and education -- South Africa -- Grahamstown Curriculum planning Second language acquisition Public schools -- South Africa -- Grahamstown Language policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3630 , http://hdl.handle.net/10962/d1012072
- Description: This study looks at the curriculum outcomes, teaching practices and learner competencies in isiXhosa at three Eastern Cape schools and across three different grades, 7-9. It explores the link between language learning and teaching as well as the teaching strategies used within the classroom. In particular, the study seeks to analyse how isiXhosa is taught at three different levels of instruction, namely at Home Language (HL), First Additional Language (FAL) and Second Additional Language (SAL) levels. Qualitative methods were used, and the study took the form of interpretive case studies within the respective schools. The purpose of using multiple case studies was to investigate the reality within the three sites selected. The three schools had three extreme settings, in the sense that one of the schools is a rich isiXhosa environment and the other two schools are English environments. The tools used for data gathering were interviews, classroom observations, and an analysis of documents from the Department of Basic Education. Data was then presented and analysed in Chapter 4 and 5 against the backdrop of an extensive literature review in Chapter 2 as well as a detailed methodological approach as outlined in Chapter 3. One of the findings of this research indicates that in two of the schools the teaching culture is largely from a western perspective, whereas in one of the schools the learners are primarily isiXhosa speaking and teachers use a different linguistic approach to imparting knowledge. In the private and ex-Model C school it was found that a lack of exposure to isiXhosa is the primary cause of language problems for L2 learners. Secondly the L1 is not appropriately maintained or promoted in the school environment because it is presumed that learners are sufficiently exposed to their L1 at home. The research found therefore that in this particular schooling environment there is an inconsistency between the curricula that is taught in relation to the linguistic abilities of the learners, many of whom are mother tongue speakers of isiXhosa. Furthermore and more generally, it was found that teachers are still not well informed concerning South Africa’s Language-in-Education-Policy and there is a need for more inservice training that will focus on the nature of additional language acquisition in order to address the challenges of teaching these languages. The thesis concludes that extensive work needs to be done in order to reposition the teaching of isiXhosa at all three levels, but particularly at FAL level. This research shows that there is a disjuncture between the proposed curriculum/learning outcomes and the standards or levels achieved by the learners, more especially at FAL and SAL where oral proficiency in isiXhosa remains a challenge. Specific recommendations are contained in the final chapter of the thesis which also makes reference to the draft policy of the Ministry of Basic Education regarding the incremental introduction of the teaching of African languages from 2014 onwards. This thesis also makes takes as a point of departure the importance of multilingualism in a multicultural society such as South Africa where language is suggested as a strong factor in the fostering of social cohesion. It is for this reason that the thesis argues that the expert teaching of African languages, in this case isiXhosa, at both mother tongue and second language levels is of fundamental importance to the future of South African society.
- Full Text:
- Date Issued: 2014
- Authors: Fobe, Mila Pamella
- Date: 2014
- Subjects: Xhosa language -- Study and teaching (Primary) -- South Africa -- Grahamstown Xhosa language -- Study and teaching (Secondary) -- South Africa -- Grahamstown Language and education -- South Africa -- Grahamstown Curriculum planning Second language acquisition Public schools -- South Africa -- Grahamstown Language policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3630 , http://hdl.handle.net/10962/d1012072
- Description: This study looks at the curriculum outcomes, teaching practices and learner competencies in isiXhosa at three Eastern Cape schools and across three different grades, 7-9. It explores the link between language learning and teaching as well as the teaching strategies used within the classroom. In particular, the study seeks to analyse how isiXhosa is taught at three different levels of instruction, namely at Home Language (HL), First Additional Language (FAL) and Second Additional Language (SAL) levels. Qualitative methods were used, and the study took the form of interpretive case studies within the respective schools. The purpose of using multiple case studies was to investigate the reality within the three sites selected. The three schools had three extreme settings, in the sense that one of the schools is a rich isiXhosa environment and the other two schools are English environments. The tools used for data gathering were interviews, classroom observations, and an analysis of documents from the Department of Basic Education. Data was then presented and analysed in Chapter 4 and 5 against the backdrop of an extensive literature review in Chapter 2 as well as a detailed methodological approach as outlined in Chapter 3. One of the findings of this research indicates that in two of the schools the teaching culture is largely from a western perspective, whereas in one of the schools the learners are primarily isiXhosa speaking and teachers use a different linguistic approach to imparting knowledge. In the private and ex-Model C school it was found that a lack of exposure to isiXhosa is the primary cause of language problems for L2 learners. Secondly the L1 is not appropriately maintained or promoted in the school environment because it is presumed that learners are sufficiently exposed to their L1 at home. The research found therefore that in this particular schooling environment there is an inconsistency between the curricula that is taught in relation to the linguistic abilities of the learners, many of whom are mother tongue speakers of isiXhosa. Furthermore and more generally, it was found that teachers are still not well informed concerning South Africa’s Language-in-Education-Policy and there is a need for more inservice training that will focus on the nature of additional language acquisition in order to address the challenges of teaching these languages. The thesis concludes that extensive work needs to be done in order to reposition the teaching of isiXhosa at all three levels, but particularly at FAL level. This research shows that there is a disjuncture between the proposed curriculum/learning outcomes and the standards or levels achieved by the learners, more especially at FAL and SAL where oral proficiency in isiXhosa remains a challenge. Specific recommendations are contained in the final chapter of the thesis which also makes reference to the draft policy of the Ministry of Basic Education regarding the incremental introduction of the teaching of African languages from 2014 onwards. This thesis also makes takes as a point of departure the importance of multilingualism in a multicultural society such as South Africa where language is suggested as a strong factor in the fostering of social cohesion. It is for this reason that the thesis argues that the expert teaching of African languages, in this case isiXhosa, at both mother tongue and second language levels is of fundamental importance to the future of South African society.
- Full Text:
- Date Issued: 2014
Isolation and characterization of genes encoding heat shock protein 70s (hsp 70s) from two species of the coelacanth, Latimeria chalumnae and Latimeria menadoensis
- Modisakeng, Keoagile William
- Authors: Modisakeng, Keoagile William
- Date: 2007
- Subjects: Coelacanth Coelacanth -- Genetics Heat shock proteins Molecular chaperones Proteins -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3971 , http://hdl.handle.net/10962/d1004030
- Description: The extant coelacanths have a close resemblance to the coelacanth fossil records dating back to 230mya. Like their predecessors, the extant coelacanths inhabit rocky caves at a depth of 100-300m below sea level. In the Comoros, the water temperature at these depths is estimated to fluctuate between 14-20°C. High-level adaptation to these environment and lack of competition are thought to have led to the morphological uniformity and slow change throughout the history of the coelacanths. Under stress conditions, proteins unfold or misfold leading to the formation of aggregates. Molecular chaperones facilitate the correct folding of other proteins so that they can attain a stable tertiary structure. In addition, molecular chaperones aid the refolding of denatured proteins and the degradation of terminally misfolded protein after cellular stress. Heat shock proteins form one of the major classes of molecular chaperones. Here we show that, despite high-level adaptation to a unique habitat and slow change, the genome of the coelacanth encodes the major and highly conserved molecular chaperone, Hsp70. Latimeria menadoensis and Latimeria chalumnae contain intronless hsp70 genes encoding Hsp70 proteins archetypal of known Hsp70s. Based on the coelacanth codon usage, we have shown that bacterial protein expression systems, particularly Escherichia coli, may not be appropriate for the overproduction of coelacanth Hsp70s and coelacanth proteins in general. Also interesting, was the discovery that like the rat Hsc70, the L. menadoensis Hsp70 could not reverse thermal sensitivity in a temperate sensitive E. coli DnaK mutant strain, BB2362. We also report the successful isolation of a 1.2 kb region of L. menadoensis hsp70 upstream regulatory region. This region contain three putative heat shock elements, a TATA- box and two CAAT-boxes. This regulatory region resembled the Xenopus, mouse, and particularly tilapia hsp70 promoters, all of which have been shown to drive the expression of reporter genes in a heat dependent manner. Taken together, this data is the first to strongly suggest an inducible Hsp70-base cytoprotection mechanism in the coelacanth. It further provides basis to formulate testable predictions about the regulation, structure and function of Hsp70s in the living fossil, Latimeria.
- Full Text:
- Date Issued: 2007
- Authors: Modisakeng, Keoagile William
- Date: 2007
- Subjects: Coelacanth Coelacanth -- Genetics Heat shock proteins Molecular chaperones Proteins -- Analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3971 , http://hdl.handle.net/10962/d1004030
- Description: The extant coelacanths have a close resemblance to the coelacanth fossil records dating back to 230mya. Like their predecessors, the extant coelacanths inhabit rocky caves at a depth of 100-300m below sea level. In the Comoros, the water temperature at these depths is estimated to fluctuate between 14-20°C. High-level adaptation to these environment and lack of competition are thought to have led to the morphological uniformity and slow change throughout the history of the coelacanths. Under stress conditions, proteins unfold or misfold leading to the formation of aggregates. Molecular chaperones facilitate the correct folding of other proteins so that they can attain a stable tertiary structure. In addition, molecular chaperones aid the refolding of denatured proteins and the degradation of terminally misfolded protein after cellular stress. Heat shock proteins form one of the major classes of molecular chaperones. Here we show that, despite high-level adaptation to a unique habitat and slow change, the genome of the coelacanth encodes the major and highly conserved molecular chaperone, Hsp70. Latimeria menadoensis and Latimeria chalumnae contain intronless hsp70 genes encoding Hsp70 proteins archetypal of known Hsp70s. Based on the coelacanth codon usage, we have shown that bacterial protein expression systems, particularly Escherichia coli, may not be appropriate for the overproduction of coelacanth Hsp70s and coelacanth proteins in general. Also interesting, was the discovery that like the rat Hsc70, the L. menadoensis Hsp70 could not reverse thermal sensitivity in a temperate sensitive E. coli DnaK mutant strain, BB2362. We also report the successful isolation of a 1.2 kb region of L. menadoensis hsp70 upstream regulatory region. This region contain three putative heat shock elements, a TATA- box and two CAAT-boxes. This regulatory region resembled the Xenopus, mouse, and particularly tilapia hsp70 promoters, all of which have been shown to drive the expression of reporter genes in a heat dependent manner. Taken together, this data is the first to strongly suggest an inducible Hsp70-base cytoprotection mechanism in the coelacanth. It further provides basis to formulate testable predictions about the regulation, structure and function of Hsp70s in the living fossil, Latimeria.
- Full Text:
- Date Issued: 2007
An investigation of Wikipedia translation as an additive pedagogy for Oshikwanyama first language learning
- Authors: Hautemo, Aletta Mweneni
- Date: 2014
- Subjects: Kuanyama language -- Study and teaching (Secondary) -- Computer-assisted instruction , Kuanyama language -- Machine translating -- Namibia , Language and languages -- Study and teaching (Secondary) -- Computer-assisted instruction , Computer-assisted instruction -- Study and teaching (Secondary) -- Namibia , Information technology -- Study and teaching (Secondary) -- Namibia , Educational technology -- Namibia , Wikipedia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1982 , http://hdl.handle.net/10962/d1013139
- Description: The integration of Information and Communication Technology in the indigenous language classroom lags behind compared to other subjects. In many ways, indigenous language teachers find it difficult and to some extent, impossible to integrate ICT into their classroom activities. The focus of this study is to explore the ways in which ICT could be used as a learning tool in an Oshikwanyama First Language classroom. I investigated the use of Wikipedia translation as an additional teaching and learning tool. I concentrated on the impact that ICT tools have on learning, and the motivation it has on learners to learn Oshikwanyama. This qualitative case study was conducted in an urban school in northern Namibia. The adoption of ICT at the school is good as there is a full-fledged computer lab with unlimited wireless internet access. This was a requirement for the project to enable the participants to work online. I purposefully chose higher-level learners (Secondary phase) for this study. I conducted a survey with them on their access to and use of ICT devices in their daily lives, and thereafter conducted a basic computer workshop and a Wikipedia translation project with them. My research findings show that although the use of ICT is part of the learners’ lives, most of the communication through ICT devices is done in English not Oshikwanyama. Wikipedia translation offers a stimulating learning platform for learners to learn Oshikwanyama and English at the same time and this improved their performance in both languages. Furthermore, the Wikipedia translation, which was done collaboratively, gave learners the confidence to work with other learners to create knowledge. Lastly, Wikipedia translation motivates learners to learn Oshikwanyama and use it in their daily ICT interaction.
- Full Text:
- Date Issued: 2014
- Authors: Hautemo, Aletta Mweneni
- Date: 2014
- Subjects: Kuanyama language -- Study and teaching (Secondary) -- Computer-assisted instruction , Kuanyama language -- Machine translating -- Namibia , Language and languages -- Study and teaching (Secondary) -- Computer-assisted instruction , Computer-assisted instruction -- Study and teaching (Secondary) -- Namibia , Information technology -- Study and teaching (Secondary) -- Namibia , Educational technology -- Namibia , Wikipedia
- Language: English
- Type: Thesis , Masters , MEd
- Identifier: vital:1982 , http://hdl.handle.net/10962/d1013139
- Description: The integration of Information and Communication Technology in the indigenous language classroom lags behind compared to other subjects. In many ways, indigenous language teachers find it difficult and to some extent, impossible to integrate ICT into their classroom activities. The focus of this study is to explore the ways in which ICT could be used as a learning tool in an Oshikwanyama First Language classroom. I investigated the use of Wikipedia translation as an additional teaching and learning tool. I concentrated on the impact that ICT tools have on learning, and the motivation it has on learners to learn Oshikwanyama. This qualitative case study was conducted in an urban school in northern Namibia. The adoption of ICT at the school is good as there is a full-fledged computer lab with unlimited wireless internet access. This was a requirement for the project to enable the participants to work online. I purposefully chose higher-level learners (Secondary phase) for this study. I conducted a survey with them on their access to and use of ICT devices in their daily lives, and thereafter conducted a basic computer workshop and a Wikipedia translation project with them. My research findings show that although the use of ICT is part of the learners’ lives, most of the communication through ICT devices is done in English not Oshikwanyama. Wikipedia translation offers a stimulating learning platform for learners to learn Oshikwanyama and English at the same time and this improved their performance in both languages. Furthermore, the Wikipedia translation, which was done collaboratively, gave learners the confidence to work with other learners to create knowledge. Lastly, Wikipedia translation motivates learners to learn Oshikwanyama and use it in their daily ICT interaction.
- Full Text:
- Date Issued: 2014
Bioaccumulation and histopathology of copper in Oreochromis mossambicus
- Authors: Naigaga, Irene
- Date: 2003
- Subjects: Mozambique tilapia , Copper , Marine toxins , Fishes -- Effect of water pollution on , Water -- Pollution -- Environmental aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5234 , http://hdl.handle.net/10962/d1005077 , Mozambique tilapia , Copper , Marine toxins , Fishes -- Effect of water pollution on , Water -- Pollution -- Environmental aspects
- Description: Cu is one of the most toxic elements that affect fish populations when the fish are exposed to concentrations exceeding their tolerance. To investigate the effects of elementary Cu on aspects of bioconcentration, histology and behaviour, O. mossambicus were exposed to 0 and 0.75 ± 0.20 mg/l of Cu for 96 hours (short-term study), and 0, 0.11 ± 0.02, 0.29 ± 0.02, and 0.47 ± 0.04 mg/l of Cu for 64 days (longterm study) under controlled conditions in the laboratory. For the long-term study fish were sampled for gills, liver, and kidney Cu accumulation analysis after 1, 32 and 64 days of exposure and after 1, 2, 4, 16, 32, and 64 days for gills, liver and spleen histology analysis. Cu accumulation was concentration-duration dependent with the highest accumulation capacity in the liver. A multifactor linear model was developed for the relationship between exposure dose, exposure duration and Cu accumulation in the organs with the liver model: Log L = 3.35 + 0.85W + 0.31T (r² = 0.892) giving a better fit than the gills: G = −35.09 + 10.58W + 17.58T (r² = 0.632). Where L = Cu accumulation values in the liver, G = Cu accumulation values in the gills (both in μg/g dry mass); W = exposure dose in water (mg/l); and T = exposure time (days). Using this model Cu accumulation in organs can be estimated when exposure concentration and duration is known. This model should be tested under different conditions to determine the potential of the model in monitoring Cu toxicity in the environment. Lesions were observed in the liver, gills and spleen in all Cu treatments at all exposure concentration and exposure durations. However, the incidence and the degree of alteration was related to the concentration of Cu and duration of exposure. The sequential appearance of lesions in the order of, hepatic vacuolar degeneration, fatty degeneration and necrosis indicated a gradual increase in liver damage with larger duration of exposure time and increasing Cu concentration. The initial lesions in the gills were manifested as hypertrophy and hyperplasia of the gill epithelium causing increase in the thickness of the secondary lamellae, mucous cell hypertrophy and proliferation, mucous hypersecretion, proliferation of eosinophilic granule cells and hyperplasia of interlamellar cells. With increase in exposure time, necrosis of the eosinophilic granule cells, lamellar oedema, epithelial desquamation and increase in severity of lamellar hyperplasia were observed. These lesions indicated an initial defence mechanism of the fish against Cu toxicity followed by advanced histological changes that were related to Cu concentration and duration of exposure. Changes in the spleen were haemosiderosis, increase in the white pulp and macrophage centres, reduction in the red pulp, and necrosis suggesting that fish exposed to environmentally relevant levels of Cu may be histopathologically altered leading to anaemia and immunosuppression. Regression analysis was used to quantify the relationship between the total activity of the fish, and duration of exposure. There was a gradual decline in fish activity related to Cu concentration and duration of exposure before introducing food into the tanks. There was a constant activity after introducing food in the tanks at the control and 0.11 ± 0.02 mg/l Cu exposure levels irrespective of exposure time. Analysis of covariance (ANCOVA) was used to test for the difference in slopes between treatments. There was no significant difference (p > 0.05) between slopes of the control and 0.11 ± 0.02 mg/l Cu, and between 0.29 ± 0.02 and 47 ± 0.04 mg/l Cu before and after introducing food in the tanks. The slopes of both the control and 0.11 ± 0.02 mg/l Cu were significantly different from those of 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu (p < 0.05). There were significant differences in the mean opercular movements per minute between treatments (p < 0.05). There was hyperventilation at 0.11 ± 0.02 mg/l Cu i.e. 87 ± 18 opercular movements per minute (mean ± standard deviation) and hypoventilation at 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu i.e. 37 ± 34 and 13 ± 6 opercular movements per minute compared to the control. Hypo- and hyperventilation were related to the lesser and greater gill damage, respectively. In conclusion Cu accumulation and effects on histology of the liver, gills and were related to the concentration of Cu in the water and duration of exposure showing a gradual increase in incidence and intensity with larger duration of exposure time and increasing Cu concentration. The fish were initially able to homeostatically regulate and detoxify Cu. However, as the exposure continued, the homeostatic mechanism appears to have failed to cope with the increasing metal burden causing advanced histological changes.
- Full Text:
- Date Issued: 2003
- Authors: Naigaga, Irene
- Date: 2003
- Subjects: Mozambique tilapia , Copper , Marine toxins , Fishes -- Effect of water pollution on , Water -- Pollution -- Environmental aspects
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5234 , http://hdl.handle.net/10962/d1005077 , Mozambique tilapia , Copper , Marine toxins , Fishes -- Effect of water pollution on , Water -- Pollution -- Environmental aspects
- Description: Cu is one of the most toxic elements that affect fish populations when the fish are exposed to concentrations exceeding their tolerance. To investigate the effects of elementary Cu on aspects of bioconcentration, histology and behaviour, O. mossambicus were exposed to 0 and 0.75 ± 0.20 mg/l of Cu for 96 hours (short-term study), and 0, 0.11 ± 0.02, 0.29 ± 0.02, and 0.47 ± 0.04 mg/l of Cu for 64 days (longterm study) under controlled conditions in the laboratory. For the long-term study fish were sampled for gills, liver, and kidney Cu accumulation analysis after 1, 32 and 64 days of exposure and after 1, 2, 4, 16, 32, and 64 days for gills, liver and spleen histology analysis. Cu accumulation was concentration-duration dependent with the highest accumulation capacity in the liver. A multifactor linear model was developed for the relationship between exposure dose, exposure duration and Cu accumulation in the organs with the liver model: Log L = 3.35 + 0.85W + 0.31T (r² = 0.892) giving a better fit than the gills: G = −35.09 + 10.58W + 17.58T (r² = 0.632). Where L = Cu accumulation values in the liver, G = Cu accumulation values in the gills (both in μg/g dry mass); W = exposure dose in water (mg/l); and T = exposure time (days). Using this model Cu accumulation in organs can be estimated when exposure concentration and duration is known. This model should be tested under different conditions to determine the potential of the model in monitoring Cu toxicity in the environment. Lesions were observed in the liver, gills and spleen in all Cu treatments at all exposure concentration and exposure durations. However, the incidence and the degree of alteration was related to the concentration of Cu and duration of exposure. The sequential appearance of lesions in the order of, hepatic vacuolar degeneration, fatty degeneration and necrosis indicated a gradual increase in liver damage with larger duration of exposure time and increasing Cu concentration. The initial lesions in the gills were manifested as hypertrophy and hyperplasia of the gill epithelium causing increase in the thickness of the secondary lamellae, mucous cell hypertrophy and proliferation, mucous hypersecretion, proliferation of eosinophilic granule cells and hyperplasia of interlamellar cells. With increase in exposure time, necrosis of the eosinophilic granule cells, lamellar oedema, epithelial desquamation and increase in severity of lamellar hyperplasia were observed. These lesions indicated an initial defence mechanism of the fish against Cu toxicity followed by advanced histological changes that were related to Cu concentration and duration of exposure. Changes in the spleen were haemosiderosis, increase in the white pulp and macrophage centres, reduction in the red pulp, and necrosis suggesting that fish exposed to environmentally relevant levels of Cu may be histopathologically altered leading to anaemia and immunosuppression. Regression analysis was used to quantify the relationship between the total activity of the fish, and duration of exposure. There was a gradual decline in fish activity related to Cu concentration and duration of exposure before introducing food into the tanks. There was a constant activity after introducing food in the tanks at the control and 0.11 ± 0.02 mg/l Cu exposure levels irrespective of exposure time. Analysis of covariance (ANCOVA) was used to test for the difference in slopes between treatments. There was no significant difference (p > 0.05) between slopes of the control and 0.11 ± 0.02 mg/l Cu, and between 0.29 ± 0.02 and 47 ± 0.04 mg/l Cu before and after introducing food in the tanks. The slopes of both the control and 0.11 ± 0.02 mg/l Cu were significantly different from those of 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu (p < 0.05). There were significant differences in the mean opercular movements per minute between treatments (p < 0.05). There was hyperventilation at 0.11 ± 0.02 mg/l Cu i.e. 87 ± 18 opercular movements per minute (mean ± standard deviation) and hypoventilation at 0.29 ± 0.02 and 0.47 ± 0.04 mg/l Cu i.e. 37 ± 34 and 13 ± 6 opercular movements per minute compared to the control. Hypo- and hyperventilation were related to the lesser and greater gill damage, respectively. In conclusion Cu accumulation and effects on histology of the liver, gills and were related to the concentration of Cu in the water and duration of exposure showing a gradual increase in incidence and intensity with larger duration of exposure time and increasing Cu concentration. The fish were initially able to homeostatically regulate and detoxify Cu. However, as the exposure continued, the homeostatic mechanism appears to have failed to cope with the increasing metal burden causing advanced histological changes.
- Full Text:
- Date Issued: 2003
PyMORESANE: A Pythonic and CUDA-accelerated implementation of the MORESANE deconvolution algorithm
- Authors: Kenyon, Jonathan
- Date: 2015
- Subjects: Radio astronomy , Imaging systems in astronomy , MOdel REconstruction by Synthesis-ANalysis Estimators (MORESANE)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5563 , http://hdl.handle.net/10962/d1020098
- Description: The inadequacies of the current generation of deconvolution algorithms are rapidly becoming apparent as new, more sensitive radio interferometers are constructed. In light of these inadequacies, there is renewed interest in the field of deconvolution. Many new algorithms are being developed using the mathematical framework of compressed sensing. One such technique, MORESANE, has recently been shown to be a powerful tool for the recovery of faint difuse emission from synthetic and simulated data. However, the original implementation is not well-suited to large problem sizes due to its computational complexity. Additionally, its use of proprietary software prevents it from being freely distributed and used. This has motivated the development of a freely available Python implementation, PyMORESANE. This thesis describes the implementation of PyMORESANE as well as its subsequent augmentation with MPU and GPGPU code. These additions accelerate the algorithm and thus make it competitive with its legacy counterparts. The acceleration of the algorithm is verified by means of benchmarking tests for varying image size and complexity. Additionally, PyMORESANE is shown to work not only on synthetic data, but on real observational data. This verification means that the MORESANE algorithm, and consequently the PyMORESANE implementation, can be added to the current arsenal of deconvolution tools.
- Full Text:
- Date Issued: 2015
- Authors: Kenyon, Jonathan
- Date: 2015
- Subjects: Radio astronomy , Imaging systems in astronomy , MOdel REconstruction by Synthesis-ANalysis Estimators (MORESANE)
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:5563 , http://hdl.handle.net/10962/d1020098
- Description: The inadequacies of the current generation of deconvolution algorithms are rapidly becoming apparent as new, more sensitive radio interferometers are constructed. In light of these inadequacies, there is renewed interest in the field of deconvolution. Many new algorithms are being developed using the mathematical framework of compressed sensing. One such technique, MORESANE, has recently been shown to be a powerful tool for the recovery of faint difuse emission from synthetic and simulated data. However, the original implementation is not well-suited to large problem sizes due to its computational complexity. Additionally, its use of proprietary software prevents it from being freely distributed and used. This has motivated the development of a freely available Python implementation, PyMORESANE. This thesis describes the implementation of PyMORESANE as well as its subsequent augmentation with MPU and GPGPU code. These additions accelerate the algorithm and thus make it competitive with its legacy counterparts. The acceleration of the algorithm is verified by means of benchmarking tests for varying image size and complexity. Additionally, PyMORESANE is shown to work not only on synthetic data, but on real observational data. This verification means that the MORESANE algorithm, and consequently the PyMORESANE implementation, can be added to the current arsenal of deconvolution tools.
- Full Text:
- Date Issued: 2015
Development and optimisation of a novel Plasmodium falciparum Hsp90-Hop interaction assay
- Authors: Wambua, Lynn
- Date: 2018
- Subjects: Plasmodium falciparum , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Antimalarials
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62626 , vital:28216
- Description: Protein-protein interactions are involved in a range of disease processes and thus have become the focus of many drug discovery programs. Widespread drug resistance to all currently used antimalarial drugs drives the search for alternative drug targets with novel mechanisms of action that offer new therapeutic options. Molecular chaperones such as heat shock proteins facilitate protein folding, play a role in protein trafficking and prevent protein misfolding in cells under stress. Heat shock protein 90 (Hsp90) is a well-studied chaperone that has been the focus of cancer drug development with moderate success. In Plasmodium falciparum (P. falciparum), heat shock proteins are thought to play a vital role in parasite survival of the physiologically diverse habitats of the parasite lifecycle and because Hsp90 is prominently expressed in P. falciparum, the chaperone is considered a potentially ideal drug target. Hsp90 function in cells is regulated by interactions with co-chaperones, which includes Heat shock protein 70-Heat shock protein 90 organising protein (Hop). As opposed to directly inhibiting Hsp90 activity, targeting Hsp90 interaction with Hop has recently been suggested as an alternative method of Hsp90 inhibition that has not been explored in P. falciparum. The aim of this research project was to demonstrate PfHsp90 and PfHop robustly interact in vitro and to facilitate high-throughput screening of PfHsp90-PfHop inhibitors by developing and optimising a novel plate capture Hsp90-Hop interaction assay. To establish the assay, the respective domains of the proteins that mediate Hsp90-Hop interaction were used (Hsp90 C- terminal domain and Hop TPR2A domain). The human Hsp90 C-terminal domain and glutathione-S-transferase (GST) coding sequences were cloned into pET-28a(+) and murine and P. falciparum TPR2A sequences into pGEX-4T-1 plasmids to enable expression of histidine-tagged and GST fusion proteins, respectively, in Escherichia coli. The P. falciparum Hsp90 C-terminal domain sequence cloned into pET-28a(+) was supplied by GenScript. The constructs were transformed into T7 Express lysYcompetent E. coli cells and subsequent small- scale expression studies showed the recombinant proteins were expressed in a soluble form allowing for subsequent protein purification. Purification of the recombinant proteins was achieved using nickel-NTA and glutathione affinity chromatography for the His-tagged (Hsp90 C-terminal domains and GST) and GST fusion proteins (TPR2A domains), respectively. The purified proteins were used to establish and optimise mammalian and P. falciparum Hsp90- Hop interaction assays on nickel-coated plates by immobilising the His-tagged C-terminal domains on the plates and detecting the binding of the GST-TPR2A domains using a colorimetric GST enzyme assay. Z’-factor values above 0.5 were observed for both assays indicating good separation between the protein interaction signals and negative control background signals, although relatively high background signals were observed for the mammalian interaction due to non-specific binding of murine TPR2A to the plate. Designed human and P. falciparum TPR peptides were observed to be effective inhibitors of the mammalian and P. falciparum interactions, demonstrating the assay’s ability to respond to inhibitor compounds. Comparison of assay performance using GST assay kit reagents and lab- prepared reagents showed the assay was more efficient using lab-prepared reagents, however, lower GST signals were observed when comparing assay performance using a custom prepared Ni-NTA plate to a purchased Ni-NTA plate. The Hsp90-Hop interaction assays were also performed using an alternative assay format in which the GST-TPR2A fusion proteins were immobilised on glutathione-coated plates and binding of the His-tagged C-terminal domains detected with a nickel-horseradish peroxidase (HRP) conjugate and a colorimetric HRP substrate. The assay showed higher interaction signals for the P. falciparum proteins but comparatively low signals for the mammalian proteins. Z’-factor values for the assay were above 0.8 for both protein sets, suggesting this assay format is superior to the GST assay. However, further optimisation of this assay format is required. This study demonstrated direct binding of PfHsp90-PfHop in vitro and established a novel and robust PfHsp90-PfHop interaction assay format that can be used in future screening campaigns.
- Full Text:
- Date Issued: 2018
- Authors: Wambua, Lynn
- Date: 2018
- Subjects: Plasmodium falciparum , Molecular chaperones , Heat shock proteins , Protein-protein interactions , Antimalarials
- Language: English
- Type: text , Thesis , Masters , MSc
- Identifier: http://hdl.handle.net/10962/62626 , vital:28216
- Description: Protein-protein interactions are involved in a range of disease processes and thus have become the focus of many drug discovery programs. Widespread drug resistance to all currently used antimalarial drugs drives the search for alternative drug targets with novel mechanisms of action that offer new therapeutic options. Molecular chaperones such as heat shock proteins facilitate protein folding, play a role in protein trafficking and prevent protein misfolding in cells under stress. Heat shock protein 90 (Hsp90) is a well-studied chaperone that has been the focus of cancer drug development with moderate success. In Plasmodium falciparum (P. falciparum), heat shock proteins are thought to play a vital role in parasite survival of the physiologically diverse habitats of the parasite lifecycle and because Hsp90 is prominently expressed in P. falciparum, the chaperone is considered a potentially ideal drug target. Hsp90 function in cells is regulated by interactions with co-chaperones, which includes Heat shock protein 70-Heat shock protein 90 organising protein (Hop). As opposed to directly inhibiting Hsp90 activity, targeting Hsp90 interaction with Hop has recently been suggested as an alternative method of Hsp90 inhibition that has not been explored in P. falciparum. The aim of this research project was to demonstrate PfHsp90 and PfHop robustly interact in vitro and to facilitate high-throughput screening of PfHsp90-PfHop inhibitors by developing and optimising a novel plate capture Hsp90-Hop interaction assay. To establish the assay, the respective domains of the proteins that mediate Hsp90-Hop interaction were used (Hsp90 C- terminal domain and Hop TPR2A domain). The human Hsp90 C-terminal domain and glutathione-S-transferase (GST) coding sequences were cloned into pET-28a(+) and murine and P. falciparum TPR2A sequences into pGEX-4T-1 plasmids to enable expression of histidine-tagged and GST fusion proteins, respectively, in Escherichia coli. The P. falciparum Hsp90 C-terminal domain sequence cloned into pET-28a(+) was supplied by GenScript. The constructs were transformed into T7 Express lysYcompetent E. coli cells and subsequent small- scale expression studies showed the recombinant proteins were expressed in a soluble form allowing for subsequent protein purification. Purification of the recombinant proteins was achieved using nickel-NTA and glutathione affinity chromatography for the His-tagged (Hsp90 C-terminal domains and GST) and GST fusion proteins (TPR2A domains), respectively. The purified proteins were used to establish and optimise mammalian and P. falciparum Hsp90- Hop interaction assays on nickel-coated plates by immobilising the His-tagged C-terminal domains on the plates and detecting the binding of the GST-TPR2A domains using a colorimetric GST enzyme assay. Z’-factor values above 0.5 were observed for both assays indicating good separation between the protein interaction signals and negative control background signals, although relatively high background signals were observed for the mammalian interaction due to non-specific binding of murine TPR2A to the plate. Designed human and P. falciparum TPR peptides were observed to be effective inhibitors of the mammalian and P. falciparum interactions, demonstrating the assay’s ability to respond to inhibitor compounds. Comparison of assay performance using GST assay kit reagents and lab- prepared reagents showed the assay was more efficient using lab-prepared reagents, however, lower GST signals were observed when comparing assay performance using a custom prepared Ni-NTA plate to a purchased Ni-NTA plate. The Hsp90-Hop interaction assays were also performed using an alternative assay format in which the GST-TPR2A fusion proteins were immobilised on glutathione-coated plates and binding of the His-tagged C-terminal domains detected with a nickel-horseradish peroxidase (HRP) conjugate and a colorimetric HRP substrate. The assay showed higher interaction signals for the P. falciparum proteins but comparatively low signals for the mammalian proteins. Z’-factor values for the assay were above 0.8 for both protein sets, suggesting this assay format is superior to the GST assay. However, further optimisation of this assay format is required. This study demonstrated direct binding of PfHsp90-PfHop in vitro and established a novel and robust PfHsp90-PfHop interaction assay format that can be used in future screening campaigns.
- Full Text:
- Date Issued: 2018
Opening 28th Annual General Meeting of SA Pharmacy Students Federation
- Authors: Henderson, Derek Scott
- Date: 1981-06-30
- Language: English
- Type: Text
- Identifier: vital:7433 , http://hdl.handle.net/10962/d1018310
- Full Text:
- Date Issued: 1981-06-30
- Authors: Henderson, Derek Scott
- Date: 1981-06-30
- Language: English
- Type: Text
- Identifier: vital:7433 , http://hdl.handle.net/10962/d1018310
- Full Text:
- Date Issued: 1981-06-30
Photophysicochemical and photodynamic studies of phthalocyanines conjugated to selected drug delivery agents
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
- Authors: Nombona, Nolwazi
- Date: 2012
- Subjects: Phthalocyanines Photochemistry Photochemotherapy Drug delivery systems Magnesium Zinc Nanoparticles Staphylococcus aureus
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4333 , http://hdl.handle.net/10962/d1004994
- Description: This work reports on the successful synthesis, characterisation and photophysical properties of new asymmetric metal free, magnesium and zinc phthalocyanines. The synthesis of symmetrical phthalocyanines is also reported. A selection of phthalocyanines have been conjugated, covalently linked, encapsulated or mixed with selected of drug delivery agents which include gold or silver nanoparticles, poly-L-lysine, liposomes and folic acid. The influence of delivery agent on the photophysical and photochemical properties of conjugated phthalocyanine is investigated. The studies showed that the Au nanoparticle significantly lowered the fluorescence quantum yield values of the phthalocyanines. The photodynamic activity of Zn phthalocyanine-ε-polylysine conjugates in the presence of nanoparticles towards the inactivation of Staphylococcus aureus showed high photoinactivation in the presence of silver nanoparticles. The presence of silver nanoparticels from the minimal inhibition concentration (MIC₅₀) studies showed remarkable growth inhibition for the tested conjugates even at low concentrations. The conjugate also showed no dark toxicity when evaluated using the chick choriallantoic membrane (CAM) assay. The efficiency of selected zinc phthalocyanine as photodynamic therapy (PDT) agents was investigated. The production of reactive oxygen species (ROS) and phototoxicity of the photosensitizers were assessed. Healthy fibroblast cells and breast cancer (MCF-7) cells were treated with either free phthalocyanine or phthalocyanine bound to either gold nanoparticles or encapsulated in liposomes. Cell viability studies showed the optimum phototoxic effect on non-malignant cells to be 4.5 J.cm⁻². The PDT effect of the liposome bound phthalocyanine showed extensive damage of the breast cancer cells. Gold nanoparticles only showed a modest improvement in PDT activity.
- Full Text:
- Date Issued: 2012
Epithermal precious metal deposits physicochemical constraints, classification characteristics and exploration guidelines
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997
- Authors: McIver, Donald A
- Date: 1997
- Subjects: Precious metals , Geothermal resources
- Language: English
- Type: Thesis , Masters , MSc
- Identifier: vital:4941 , http://hdl.handle.net/10962/d1005553 , Precious metals , Geothermal resources
- Description: Epithermal deposits include a broad range of precious metal, base metal, mercury, and stibnite deposits. These deposits exhibit a low temperature of formation (180-280°C) at pressures of less than a few hundred bars (equivalent to depths of 1.5 - 2.0lkm). Epithermal gold deposits are the product of large-scale hydrothermal systems which mostly occur in convergent plate margin settings. Associated volcanism is largely of andesitic arc (calcalkaline to alkaline), or rhyolitic back-arc type. Porphyry Cu-Mo-Au deposits form deeper in the same systems. Genetic processes within individual deposits take place in an extremely complex manner. The resultant mineral associations, alteration styles and metal deposition patterns are even more complicated. Many attempts have been made to classify epithermal deposits based on mineralogy and alteration, host rocks, deposit form, genetic models, and standard deposits. For the explorationist, the most useful classification schemes should be brief, simple, descriptive, observationally based, and informative. Ultimately, two distinct styles of epithermal gold deposits are readily recognised: high-sulphidation, acid sulphate and low-sulphidation, adularia-sericite types. The terms high-sulphidation (HS) and low-sulphidation (IS) are based on the sulphidation state of associated sulphide minerals, which, along with characteristic hydrothermal alteration, reflect fundamental chemical differences in the epithermal environment. Highsulphidation-type deposits form in the root zones of volcanic domes from acid waters that contain residual magmatic volatiles. The low-sulphidation-type deposits form in geothermal systems where surficial waters mix with deeper, heated saline waters in a lateral flow regime, where neutral to weakly acidic, alkali chloride waters are dominant. The HSILS classification, combined with a simple description of the form of the deposit, conveys a large amount of information on mineralogy, alteration, and spatial characteristics of the mineralisation, and allows inferences to be drawn regarding likely regional controls, and the characteristics of the ore-forming fluids. The modern understanding of these environments allows us to quite effectively identify the most probable foci of mineral deposition in any given district. Current knowledge of these deposits has been derived from studies of active geothermal systems. Through comparison with alteration zones within these systems, the exploration geologist may determine the potential distribution and types of ore in a fossil geothermal system. Alteration zoning specifically can be used as a guide towards the most prospective part of the system. Epithermal gold deposits of both HS- and LS-styles are nevertheless profoundly difficult exploration targets. Successful exploration must rely on the integration of a variety of exploration techniques, guided by an understanding of the characteristics of the deposits and the processes that form them. There are no simple formulae for success in epithermal exploration: what works best must be determined for each terrain and each prospect. On a regional scale tectonic, igneous and structural settings can be used, together with assessment of the depth of erosion, to select areas for project area scale exploration. Integrated geological-geophysical interpretation derived from airborne geophysics providesa basis of targeting potential ore environments for follow-up. Geology, geochemistry and surface geophysics localise mineral concentrations within these target areas
- Full Text:
- Date Issued: 1997