Learners' numeracy progression and the role of mediation in the context of two after school mathematics clubs
- Authors: Stott, Deborah Ann
- Date: 2015
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , After-school programs -- South Africa , Numeracy -- Study and teaching (Elementary) -- South Africa , Learning, Psychology of , Education -- Research -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2017 , http://hdl.handle.net/10962/d1017181
- Description: National and international assessment results, research studies and reports point to South Africa as having educational challenges, specifically with mathematics, science and language. Addressing some of these issues is a key aim for the SANC project at Rhodes University, the context in which this study takes place. Working from a broad Vygotskian perspective of learning and development, this study had a dual focus and investigated how Grade 3 learners’ mathematical proficiency progressed (or not) whilst participating in after school maths clubs over the course of a year, and explored how the mediation offered in the clubs enabled or constrained the emergence of zones of proximal development (ZPD) and thus learning for the club learners. Methodologically, this study works within a largely qualitative, interpretive research paradigm and is designed using a longitudinal case study research strategy. Two after school maths clubs formed the empirical field. The study drew on a range of data collection methods to investigate the dual nature of the research questions for Grade 3 learners. Examples include adapted one-to-one mathematical proficiency interviews and paired task based interviews. The study highlighted the relationship between the multiple roles I played both within the research study and within the SANC project context and emphasises the influence and future implications for these various roles within the SANC project and beyond in terms of my own role as club mentor, for the future design of the SANC project maths club programme and for broader teacher and club facilitator development within and beyond the project. This study has offered insight into how mathematical proficiency may develop in Grade 3 South African learners and as such is an important contribution to the newly developing field of both numeracy and primary educational research in Southern Africa. Additionally, the research findings point to the clubs, as an example of an out-of-school time (OST) programme, providing potentially enabling spaces for both recovery and extension of mathematical proficiency in learners as these spaces are free from several contextual constraints that teachers face in their classrooms. Furthermore, it was found that learners showed development of their conceptual understanding, procedural fluency and adaptive reasoning as proposed by Kilpatrick, Swafford and Findell (2001). The use of various elements of the Maths Recovery (MR) programme (Wright, 2003) in the research process has highlighted various important contributions for broader research. For example, the need to investigate less time consuming approaches to both diagnostic assessment and learner mathematical profiling. Findings from this study support Meira and Lerman’s (2001, 2009) recently developed notion that catching attention is key to the creation or emergence of a ZPD. The study found that a combination of ‘attention catching’ and ‘tuning in’ enabled the creation (emergence) and sustainment of ZPDs in club learners. The study proposed the notion of tuning in where participants in a mathematical interaction continually adjust to each other in order to communicate mathematically. Furthermore, the study found that when attention is not caught or the participants are not tuned in, the learning activity may still be useful in assisting learners to consolidate their existing learning and / or build confidence and as such is particularly relevant to the South African context where fluency in calculating is weak (Hoadley, 2012; Schollar, 2008). This emergent notion of ‘flow’ additionally can play a supporting role in the emergence of a ZPD. The study also found that the manner in which the mediation was offered is important. The results show that the mathematical contributions learners make during interactions captured the mentors’ attention and resulted in mediation that was intentional but spontaneous, flexible, responsive and in-the-moment. This study makes theoretical and methodological contributions to various aspects of mathematics education research particularly with regard to how ZPDs emerge and are sustained and how mediation is offered to facilitate the emergence of ZPDs. Additionally, some aspects of the Learning Framework in Number (LFIN) as part of the Maths Recovery programme have been extended to work in a South African after school club context and to provide useful information for both learner progression over time and for planning of club activities. As such this study thus also contributes to the newly developing field of primary mathematics research in South Africa and to the body of research on primary after school learning programmes both locally and internationally.
- Full Text:
- Date Issued: 2015
- Authors: Stott, Deborah Ann
- Date: 2015
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , After-school programs -- South Africa , Numeracy -- Study and teaching (Elementary) -- South Africa , Learning, Psychology of , Education -- Research -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2017 , http://hdl.handle.net/10962/d1017181
- Description: National and international assessment results, research studies and reports point to South Africa as having educational challenges, specifically with mathematics, science and language. Addressing some of these issues is a key aim for the SANC project at Rhodes University, the context in which this study takes place. Working from a broad Vygotskian perspective of learning and development, this study had a dual focus and investigated how Grade 3 learners’ mathematical proficiency progressed (or not) whilst participating in after school maths clubs over the course of a year, and explored how the mediation offered in the clubs enabled or constrained the emergence of zones of proximal development (ZPD) and thus learning for the club learners. Methodologically, this study works within a largely qualitative, interpretive research paradigm and is designed using a longitudinal case study research strategy. Two after school maths clubs formed the empirical field. The study drew on a range of data collection methods to investigate the dual nature of the research questions for Grade 3 learners. Examples include adapted one-to-one mathematical proficiency interviews and paired task based interviews. The study highlighted the relationship between the multiple roles I played both within the research study and within the SANC project context and emphasises the influence and future implications for these various roles within the SANC project and beyond in terms of my own role as club mentor, for the future design of the SANC project maths club programme and for broader teacher and club facilitator development within and beyond the project. This study has offered insight into how mathematical proficiency may develop in Grade 3 South African learners and as such is an important contribution to the newly developing field of both numeracy and primary educational research in Southern Africa. Additionally, the research findings point to the clubs, as an example of an out-of-school time (OST) programme, providing potentially enabling spaces for both recovery and extension of mathematical proficiency in learners as these spaces are free from several contextual constraints that teachers face in their classrooms. Furthermore, it was found that learners showed development of their conceptual understanding, procedural fluency and adaptive reasoning as proposed by Kilpatrick, Swafford and Findell (2001). The use of various elements of the Maths Recovery (MR) programme (Wright, 2003) in the research process has highlighted various important contributions for broader research. For example, the need to investigate less time consuming approaches to both diagnostic assessment and learner mathematical profiling. Findings from this study support Meira and Lerman’s (2001, 2009) recently developed notion that catching attention is key to the creation or emergence of a ZPD. The study found that a combination of ‘attention catching’ and ‘tuning in’ enabled the creation (emergence) and sustainment of ZPDs in club learners. The study proposed the notion of tuning in where participants in a mathematical interaction continually adjust to each other in order to communicate mathematically. Furthermore, the study found that when attention is not caught or the participants are not tuned in, the learning activity may still be useful in assisting learners to consolidate their existing learning and / or build confidence and as such is particularly relevant to the South African context where fluency in calculating is weak (Hoadley, 2012; Schollar, 2008). This emergent notion of ‘flow’ additionally can play a supporting role in the emergence of a ZPD. The study also found that the manner in which the mediation was offered is important. The results show that the mathematical contributions learners make during interactions captured the mentors’ attention and resulted in mediation that was intentional but spontaneous, flexible, responsive and in-the-moment. This study makes theoretical and methodological contributions to various aspects of mathematics education research particularly with regard to how ZPDs emerge and are sustained and how mediation is offered to facilitate the emergence of ZPDs. Additionally, some aspects of the Learning Framework in Number (LFIN) as part of the Maths Recovery programme have been extended to work in a South African after school club context and to provide useful information for both learner progression over time and for planning of club activities. As such this study thus also contributes to the newly developing field of primary mathematics research in South Africa and to the body of research on primary after school learning programmes both locally and internationally.
- Full Text:
- Date Issued: 2015
Maintenance management systems of on-campus student hostels at Nigerian universities
- Authors: Adamu, Anita Dzikwi
- Date: 2015
- Subjects: School buildings -- Maintenance and repair , Dormitories -- Nigeria , Nigeria -- Student housing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9710 , http://hdl.handle.net/10948/d1020168
- Description: Most universities have long recognised the importance and contribution of on-campus hostels to the learning process. In so doing, most of these institutions have provided and maintained building facilities for academic purposes (teaching and research). Hostels are integral components of most campuses of Nigerian universities, and they are part of the built assets of the institutions in terms of both administration and maintenance management. Currently, there is little understanding of the maintenance management systems of on-campus hostel buildings in both the public and the private universities. Moreover, there is a dearth of research evidence demonstrating that there is an appreciable difference in the maintenance management systems of the Federal, State and private universities in Nigeria. This research aimed at establishing an understanding of maintenance management systems of on-campus hostel buildings at Nigerian universities owned by the Federal and State governments and the Private Sector, relative to stipulated criteria for best practice.The qualitative method of research inquiry that is rooted in the phenomenological paradigm was employed in the investigations. The research activities included a comprehensive review of the related literature and study of selected cases. The North-central geopolitical zone of Nigeria was the selected geographical scope of this research. Ten universities were purposefully selected for the study, and they include three Federal, four state and three private universities. The nature and differences in the research questions necessitated generating different forms of data. The questions that were related to the maintenance management systems for the hostels in place at the universities were addressed with the outcomes of interviews with the hostel managers. The questions that were about the structures and current conditions of the hostel buildings at the three categories of universities were addressed with data that were generated from condition assessments of the facilities and physical observations with the aid of cameras. The study reveals apparent deteriorated and unhealthy conditions of most of the on-campus hostels at the public universities, while those of the private universities are satisfactory. The research also found that the maintenance management systems in use at all the universities are reactive and lack proper planning and coordination of maintenance activities. There is no significant difference in the maintenance management systems of hostels at the public and the private universities and the systems have major negative impact on the conditions of the buildings and their performances. The research has developed a conceptual model for the study of maintenance management informed by the theoretical framework. The model considered the impact of the external environmental factors on the management and maintenance of the hostels. Secondly, the interrelationships of strategic and performance management with maintenance management in developing an effective maintenance management system were established. The study has achieved its aim of establishing an understanding of maintenance management systems of on-campus hostel buildings at Nigerian universities owned by the Federal and, State governments and the Private Sector. The maintenance management model developed in the study is recommended to maintenance management departments as a guide for effective maintenance of the built facilities in their institutions.
- Full Text:
- Date Issued: 2015
- Authors: Adamu, Anita Dzikwi
- Date: 2015
- Subjects: School buildings -- Maintenance and repair , Dormitories -- Nigeria , Nigeria -- Student housing
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9710 , http://hdl.handle.net/10948/d1020168
- Description: Most universities have long recognised the importance and contribution of on-campus hostels to the learning process. In so doing, most of these institutions have provided and maintained building facilities for academic purposes (teaching and research). Hostels are integral components of most campuses of Nigerian universities, and they are part of the built assets of the institutions in terms of both administration and maintenance management. Currently, there is little understanding of the maintenance management systems of on-campus hostel buildings in both the public and the private universities. Moreover, there is a dearth of research evidence demonstrating that there is an appreciable difference in the maintenance management systems of the Federal, State and private universities in Nigeria. This research aimed at establishing an understanding of maintenance management systems of on-campus hostel buildings at Nigerian universities owned by the Federal and State governments and the Private Sector, relative to stipulated criteria for best practice.The qualitative method of research inquiry that is rooted in the phenomenological paradigm was employed in the investigations. The research activities included a comprehensive review of the related literature and study of selected cases. The North-central geopolitical zone of Nigeria was the selected geographical scope of this research. Ten universities were purposefully selected for the study, and they include three Federal, four state and three private universities. The nature and differences in the research questions necessitated generating different forms of data. The questions that were related to the maintenance management systems for the hostels in place at the universities were addressed with the outcomes of interviews with the hostel managers. The questions that were about the structures and current conditions of the hostel buildings at the three categories of universities were addressed with data that were generated from condition assessments of the facilities and physical observations with the aid of cameras. The study reveals apparent deteriorated and unhealthy conditions of most of the on-campus hostels at the public universities, while those of the private universities are satisfactory. The research also found that the maintenance management systems in use at all the universities are reactive and lack proper planning and coordination of maintenance activities. There is no significant difference in the maintenance management systems of hostels at the public and the private universities and the systems have major negative impact on the conditions of the buildings and their performances. The research has developed a conceptual model for the study of maintenance management informed by the theoretical framework. The model considered the impact of the external environmental factors on the management and maintenance of the hostels. Secondly, the interrelationships of strategic and performance management with maintenance management in developing an effective maintenance management system were established. The study has achieved its aim of establishing an understanding of maintenance management systems of on-campus hostel buildings at Nigerian universities owned by the Federal and, State governments and the Private Sector. The maintenance management model developed in the study is recommended to maintenance management departments as a guide for effective maintenance of the built facilities in their institutions.
- Full Text:
- Date Issued: 2015
Metallophthalocyanine-gold nanoparticle conjugates for photodynamic antimicrobial chemotherapy
- Mthethwa, Thandekile Phakamisiwe
- Authors: Mthethwa, Thandekile Phakamisiwe
- Date: 2015
- Subjects: Nanochemistry , Phthalocyanines , Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4543 , http://hdl.handle.net/10962/d1017923
- Description: This thesis presents the synthesis of neutral and cationic metallophthalocyanines and their gold nanoparticles conjugates. The spectroscopic characterization of these compounds is presented herein. The studies presented in this work shows that the conjugation of gold nanoparticles influenced both photophysical and photochemical properties. Gold nanoparticles were found to enhance the singlet oxygen quantum yield while lowering the fluorescence quantum yields. This work also looks at the effect of anisotropic gold nanoparticles such as nanorods and bipyramids on the photophysical behaviour of the metallophthalocyanines. The effect of the size of the gold nanorods was investigated herein. The results show that photophysical and photochemical properties can be influenced by both size and shape of the nanoparticles. Physical characterization about the loading of nanoparticles was also looked into. Parameters such as the surface area, the number of surface atoms, the number of atoms as well as the number of nanoparticles loaded on the surface of the phthalocyanines were studied. The self-assembled monolayers formed by phthalocyanines on gold surfaces were studied using the X-ray photoelectron spectroscopy (XPS). The gold nanoparticles synthesized herein include both organic and water soluble, different capping agents (citrate, tetraammonium bromide (TAOBr) and cetrimethylammonium bromide (CTAB). The concentration of the gold nanoparticles was measured on the inductively coupled plasma (ICP) and their size and shape were obtained from the transmission electron microscopy (TEM) images. A cationic aluminium phthalocyanine and its conjugates were used for photoinactivation of bacteria and fungi. The results show significant reduction and higher activity in the presence of gold nanoparticles, especially nanorods. A small chapter in this work presents an attempted work on the binding of metallothionein protein with protophorphyrin (IX). The pH and concentration dependent binding studies were investigated
- Full Text:
- Date Issued: 2015
- Authors: Mthethwa, Thandekile Phakamisiwe
- Date: 2015
- Subjects: Nanochemistry , Phthalocyanines , Photochemistry
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4543 , http://hdl.handle.net/10962/d1017923
- Description: This thesis presents the synthesis of neutral and cationic metallophthalocyanines and their gold nanoparticles conjugates. The spectroscopic characterization of these compounds is presented herein. The studies presented in this work shows that the conjugation of gold nanoparticles influenced both photophysical and photochemical properties. Gold nanoparticles were found to enhance the singlet oxygen quantum yield while lowering the fluorescence quantum yields. This work also looks at the effect of anisotropic gold nanoparticles such as nanorods and bipyramids on the photophysical behaviour of the metallophthalocyanines. The effect of the size of the gold nanorods was investigated herein. The results show that photophysical and photochemical properties can be influenced by both size and shape of the nanoparticles. Physical characterization about the loading of nanoparticles was also looked into. Parameters such as the surface area, the number of surface atoms, the number of atoms as well as the number of nanoparticles loaded on the surface of the phthalocyanines were studied. The self-assembled monolayers formed by phthalocyanines on gold surfaces were studied using the X-ray photoelectron spectroscopy (XPS). The gold nanoparticles synthesized herein include both organic and water soluble, different capping agents (citrate, tetraammonium bromide (TAOBr) and cetrimethylammonium bromide (CTAB). The concentration of the gold nanoparticles was measured on the inductively coupled plasma (ICP) and their size and shape were obtained from the transmission electron microscopy (TEM) images. A cationic aluminium phthalocyanine and its conjugates were used for photoinactivation of bacteria and fungi. The results show significant reduction and higher activity in the presence of gold nanoparticles, especially nanorods. A small chapter in this work presents an attempted work on the binding of metallothionein protein with protophorphyrin (IX). The pH and concentration dependent binding studies were investigated
- Full Text:
- Date Issued: 2015
Minding your own game : self-regulation and psychological momentum among golfers
- Authors: Kingma, Graham
- Date: 2015
- Subjects: Golf -- Strategic aspects , Golf -- Psychological aspects , Athletes , Self-control , Golfers -- Conduct of life
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3260 , http://hdl.handle.net/10962/d1017883
- Description: Psychological momentum (PM) is often regarded as an important phenomenon that influences athlete performance. Nevertheless, conceptualisations of PM are criticised for being speculative, vague and impractical for scientific inquiry. In contrast, self-regulation is a long-standing, well researched concept used to explain performance outcomes, yet not clearly integrated in current PM conceptualisations. Hence, this thesis explores self-regulation relative to PM. Golf was considered to be an appropriate context for the empirical inquiries on the basis that it serves as a metaphor for managing life’s challenges. Three studies were conducted. The first study entailed a systematic conceptual analysis of PM based on previous conceptualisations and studies in relevant scientific literature. Self-regulatory processes were identified among the key psychological mechanisms and moderators related to PM. The second study aimed to identify key self-regulation strategies in PM experiences among 16 golfers. A mixed method approach including novel “walk-along” and “think aloud” data collection techniques was used. An inductive thematic analysis yielded a comprehensive typology golfing strategies. Nevertheless, the study did not find consistent strategy patterns in positive or negative PM phases. The third study explored the self-regulation of identity (ego-regulation) in relation to PM phases. A staggered multiple-baseline single-case research methodology was used with five golfers (three professionals and two amateurs). Ego-regulation was manipulated through a mindfulness-based schema mode program tailored to golf (Mindfulness for Golf; MFG). Pre-, mid- and post-intervention data showed positive changes among the participants on two dimensions of PM as well as performance outcomes. Overall the results suggest that golfers use idiosyncratic self-regulation processes to facilitate performance, but these are not directly linked to PM phases. Nonetheless, there are promising indications that enhancing ego-regulation through the MFG program facilitates positive momentum among golfers. Based on the results of the studies in this thesis, and for the sake of scientific parsimony and pragmatism, it is recommended that self-regulation models incorporating motivation are used to explain momentum in athletic activity. In this view, PM has the function of describing, not influencing, goal-driven performance
- Full Text:
- Date Issued: 2015
- Authors: Kingma, Graham
- Date: 2015
- Subjects: Golf -- Strategic aspects , Golf -- Psychological aspects , Athletes , Self-control , Golfers -- Conduct of life
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3260 , http://hdl.handle.net/10962/d1017883
- Description: Psychological momentum (PM) is often regarded as an important phenomenon that influences athlete performance. Nevertheless, conceptualisations of PM are criticised for being speculative, vague and impractical for scientific inquiry. In contrast, self-regulation is a long-standing, well researched concept used to explain performance outcomes, yet not clearly integrated in current PM conceptualisations. Hence, this thesis explores self-regulation relative to PM. Golf was considered to be an appropriate context for the empirical inquiries on the basis that it serves as a metaphor for managing life’s challenges. Three studies were conducted. The first study entailed a systematic conceptual analysis of PM based on previous conceptualisations and studies in relevant scientific literature. Self-regulatory processes were identified among the key psychological mechanisms and moderators related to PM. The second study aimed to identify key self-regulation strategies in PM experiences among 16 golfers. A mixed method approach including novel “walk-along” and “think aloud” data collection techniques was used. An inductive thematic analysis yielded a comprehensive typology golfing strategies. Nevertheless, the study did not find consistent strategy patterns in positive or negative PM phases. The third study explored the self-regulation of identity (ego-regulation) in relation to PM phases. A staggered multiple-baseline single-case research methodology was used with five golfers (three professionals and two amateurs). Ego-regulation was manipulated through a mindfulness-based schema mode program tailored to golf (Mindfulness for Golf; MFG). Pre-, mid- and post-intervention data showed positive changes among the participants on two dimensions of PM as well as performance outcomes. Overall the results suggest that golfers use idiosyncratic self-regulation processes to facilitate performance, but these are not directly linked to PM phases. Nonetheless, there are promising indications that enhancing ego-regulation through the MFG program facilitates positive momentum among golfers. Based on the results of the studies in this thesis, and for the sake of scientific parsimony and pragmatism, it is recommended that self-regulation models incorporating motivation are used to explain momentum in athletic activity. In this view, PM has the function of describing, not influencing, goal-driven performance
- Full Text:
- Date Issued: 2015
Modification and application of the decentralised wastewater treatment technology for greywater treatment to reduce water needs
- Authors: Ngqwala, Nosiphiwe P
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/103714 , vital:32290
- Description: Expected release date-April 2017
- Full Text: false
- Date Issued: 2015
- Authors: Ngqwala, Nosiphiwe P
- Date: 2015
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/103714 , vital:32290
- Description: Expected release date-April 2017
- Full Text: false
- Date Issued: 2015
Molecular systematics and biology of two closely related blowflies : Lucilia sericata and Lucilia cuprina
- Authors: Williams, Kirstin Alexa
- Date: 2015
- Subjects: Lucilia sericata , Lucilia cuprina
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5934 , http://hdl.handle.net/10962/d1017812
- Description: The greenbottle blowflies, Lucilia sericata (Meigen, 1826) and Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) are very difficult to distinguish on the basis of their external morphology. The literature suggests that these two species may be interbreeding. Sequencing two nuclear (28S rRNA and Period) and one mitochondrial (COI) gene indicated that there has been an ancient hybridization event and that mtDNA of L. sericata has become fixed in a lineage of L. cuprina through mtDNA introgression, possibly involving Wolbachia infection. This has implications for identifications of these species based on mtDNA alone. No study has shown explicitly that hybrids of L. sericata and L. cuprina can be identified morphologically. Morphological characters used to identify L. sericata and L. cuprina were scored and tested using specimens of both species and known hybrids. Discriminant function analysis of the characters successfully separated the specimens into three unambiguous groups – L. sericata, L. cuprina and hybrids. This is the first evidence that hybrids of these two species can be identified from physical characteristics.Lucilia sericata and L. cuprina have medical, veterinary and forensic importance. Knowing their distribution in South Africa would allow more effective management and utilisation of these flies. Their predicted geographic distributions in South Africa were modelled using maximum entropy analysis of selected climatic variables. The most important environmental variables in modelling their distributions were magnitude of monthly rainfall and the magnitude of the monthly maximum temperature for L. sericata, and the seasonal variation in monthly mean humidity and magnitude of monthly rainfall for L. cuprina. Both species have a widespread distribution in South Africa and one therefore cannot identify specimens of these flies by locality of capture alone.Luciliinae is a diverse and geographically widespread subfamily containing four genera - Hemipyrellia, Lucilia, Dyscritomyia and Hypopygiopsis – that all contain parasitic species ranging from saprophages to obligate parasites. The phylogenetic relationships between these genera are unclear. The 28S rRNA, COI and Period genes of 14 species of Lucilia and Hemipyrellia were partially sequenced and analysed together with 11sequences from GenBank and the Barcode of Life Database (BOLD). Lucilia sericata and L. cuprina were shown to be sister-species. Three cases of paraphylly were identified within Lucilia that affects identification of these species using mtDNA alone. Hemipyrellia consistently caused Lucilia to be paraphyletic when it was included in analyses, so Hemipyrellia should be synonymized with Lucilia. The relationships of Dyscritomyia and Hypopygiopsis to Lucilia are unclear and further studies are required. No geographic pattern was found within the different forms of parasitism within this group, but the different degrees of parasitism were phylogenetically clustered.
- Full Text:
- Date Issued: 2015
- Authors: Williams, Kirstin Alexa
- Date: 2015
- Subjects: Lucilia sericata , Lucilia cuprina
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:5934 , http://hdl.handle.net/10962/d1017812
- Description: The greenbottle blowflies, Lucilia sericata (Meigen, 1826) and Lucilia cuprina (Wiedemann, 1830) (Diptera: Calliphoridae) are very difficult to distinguish on the basis of their external morphology. The literature suggests that these two species may be interbreeding. Sequencing two nuclear (28S rRNA and Period) and one mitochondrial (COI) gene indicated that there has been an ancient hybridization event and that mtDNA of L. sericata has become fixed in a lineage of L. cuprina through mtDNA introgression, possibly involving Wolbachia infection. This has implications for identifications of these species based on mtDNA alone. No study has shown explicitly that hybrids of L. sericata and L. cuprina can be identified morphologically. Morphological characters used to identify L. sericata and L. cuprina were scored and tested using specimens of both species and known hybrids. Discriminant function analysis of the characters successfully separated the specimens into three unambiguous groups – L. sericata, L. cuprina and hybrids. This is the first evidence that hybrids of these two species can be identified from physical characteristics.Lucilia sericata and L. cuprina have medical, veterinary and forensic importance. Knowing their distribution in South Africa would allow more effective management and utilisation of these flies. Their predicted geographic distributions in South Africa were modelled using maximum entropy analysis of selected climatic variables. The most important environmental variables in modelling their distributions were magnitude of monthly rainfall and the magnitude of the monthly maximum temperature for L. sericata, and the seasonal variation in monthly mean humidity and magnitude of monthly rainfall for L. cuprina. Both species have a widespread distribution in South Africa and one therefore cannot identify specimens of these flies by locality of capture alone.Luciliinae is a diverse and geographically widespread subfamily containing four genera - Hemipyrellia, Lucilia, Dyscritomyia and Hypopygiopsis – that all contain parasitic species ranging from saprophages to obligate parasites. The phylogenetic relationships between these genera are unclear. The 28S rRNA, COI and Period genes of 14 species of Lucilia and Hemipyrellia were partially sequenced and analysed together with 11sequences from GenBank and the Barcode of Life Database (BOLD). Lucilia sericata and L. cuprina were shown to be sister-species. Three cases of paraphylly were identified within Lucilia that affects identification of these species using mtDNA alone. Hemipyrellia consistently caused Lucilia to be paraphyletic when it was included in analyses, so Hemipyrellia should be synonymized with Lucilia. The relationships of Dyscritomyia and Hypopygiopsis to Lucilia are unclear and further studies are required. No geographic pattern was found within the different forms of parasitism within this group, but the different degrees of parasitism were phylogenetically clustered.
- Full Text:
- Date Issued: 2015
Negotiating historical continuities in contested terrain : a narrative-based reflection on the post-apartheid psychosocial legacies of conscription into the South African Defence Force
- Authors: Edlmann, Tessa Margaret
- Date: 2015
- Subjects: South Africa. National Defence Force , Draft -- South Africa -- History -- 20th century , Draft -- Psychological aspects , Masculinity -- South Africa , Sociology, Military -- South Africa , Whites -- Race identity -- South Africa , South Africa -- Politics and government -- 1948-1994 , Narrative inquiry (Research method)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2608 , http://hdl.handle.net/10962/d1012811
- Description: For a 25-year period during the apartheid era in South Africa, all school-leaving white men were issued with a compulsory call-up to national military service in the South African Defence Force. It is estimated that 600 000 men were conscripted between 1968 and 1993, undergoing military training and being deployed in Namibia, Angola and South Africa. The purpose of this system of military conscription was to support both the apartheid state’s role in the “Border War” in Namibia and Angola and the suppression of anti-apartheid resistance within South Africa. It formed part of the National Party’s strategy of a “total response” to what it perceived as the “total onslaught” of communism and African nationalism. While recruiting and training young white men was the focus of the apartheid government’s strategy, all of white South African society was caught up in supporting, contesting, avoiding and resisting this system in one way or another. Rather than being a purely military endeavour, conscription into the SADF therefore comprised a social and political system with wide-ranging ramifications. The 1994 democratic elections in South Africa heralded the advent of a very different political, social and economic system to what had gone before. The focus of this research is SADF conscripts’ narrations of identity in the contested narrative terrain of post-apartheid South Africa. The thesis begins with a contextual framing of the historical, social and political systems of which conscription was a part. Drawing on narrative psychology as a theoretical framework, the thesis explores discursive resources of whiteness, masculinities and perceptions of threat in conscripts’ narrations of identity, the construction of memory fields in narrating memories of war and possible trauma, and the notions of moral injury and moral repair in dealing with legacies of war. Using a narrative discursive approach, the thesis then reflects on historical temporal threads, and narrative patterns that emerge when analysing a range of texts about the psychosocial legacies of conscription, including interviews, research, memoirs, plays, media reports, video documentaries, blogs and photographic exhibitions. Throughout the thesis, conscripts’ and others’ accounts of conscription and its legacies are regarded as cultural texts. This serves as a means to highlight both contextual narrative negotiations and the narrative-discursive patterns of conscripts’ personal accounts of their identities in the post-apartheid narrative terrain. The original contribution of this research is the development of conceptual and theoretical framings of the post-apartheid legacies of conscription. Key to this has been the use of narrative-based approaches to highlight the narrative-discursive patterns, memory fields and negotiations of narrative terrains at work in texts that focus on various aspects of conscription and its ongoing aftereffects. The concept of temporal threads has been developed to account for the emergence and shifts in these patterns over time. Existing narrative-discursive theory has formed the basis for conscripts’ negotiations of identity being identified as acts of narrative reinforcement and narrative repair. The thesis concludes with reflections on the future possibilities for articulating and supporting narrative repair that enables a shift away from historical discursive laagers and a reconfiguration of the narrative terrain within which conscripts narrate their identities. , Also known as: Edlmann, Theresa
- Full Text:
- Date Issued: 2015
- Authors: Edlmann, Tessa Margaret
- Date: 2015
- Subjects: South Africa. National Defence Force , Draft -- South Africa -- History -- 20th century , Draft -- Psychological aspects , Masculinity -- South Africa , Sociology, Military -- South Africa , Whites -- Race identity -- South Africa , South Africa -- Politics and government -- 1948-1994 , Narrative inquiry (Research method)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2608 , http://hdl.handle.net/10962/d1012811
- Description: For a 25-year period during the apartheid era in South Africa, all school-leaving white men were issued with a compulsory call-up to national military service in the South African Defence Force. It is estimated that 600 000 men were conscripted between 1968 and 1993, undergoing military training and being deployed in Namibia, Angola and South Africa. The purpose of this system of military conscription was to support both the apartheid state’s role in the “Border War” in Namibia and Angola and the suppression of anti-apartheid resistance within South Africa. It formed part of the National Party’s strategy of a “total response” to what it perceived as the “total onslaught” of communism and African nationalism. While recruiting and training young white men was the focus of the apartheid government’s strategy, all of white South African society was caught up in supporting, contesting, avoiding and resisting this system in one way or another. Rather than being a purely military endeavour, conscription into the SADF therefore comprised a social and political system with wide-ranging ramifications. The 1994 democratic elections in South Africa heralded the advent of a very different political, social and economic system to what had gone before. The focus of this research is SADF conscripts’ narrations of identity in the contested narrative terrain of post-apartheid South Africa. The thesis begins with a contextual framing of the historical, social and political systems of which conscription was a part. Drawing on narrative psychology as a theoretical framework, the thesis explores discursive resources of whiteness, masculinities and perceptions of threat in conscripts’ narrations of identity, the construction of memory fields in narrating memories of war and possible trauma, and the notions of moral injury and moral repair in dealing with legacies of war. Using a narrative discursive approach, the thesis then reflects on historical temporal threads, and narrative patterns that emerge when analysing a range of texts about the psychosocial legacies of conscription, including interviews, research, memoirs, plays, media reports, video documentaries, blogs and photographic exhibitions. Throughout the thesis, conscripts’ and others’ accounts of conscription and its legacies are regarded as cultural texts. This serves as a means to highlight both contextual narrative negotiations and the narrative-discursive patterns of conscripts’ personal accounts of their identities in the post-apartheid narrative terrain. The original contribution of this research is the development of conceptual and theoretical framings of the post-apartheid legacies of conscription. Key to this has been the use of narrative-based approaches to highlight the narrative-discursive patterns, memory fields and negotiations of narrative terrains at work in texts that focus on various aspects of conscription and its ongoing aftereffects. The concept of temporal threads has been developed to account for the emergence and shifts in these patterns over time. Existing narrative-discursive theory has formed the basis for conscripts’ negotiations of identity being identified as acts of narrative reinforcement and narrative repair. The thesis concludes with reflections on the future possibilities for articulating and supporting narrative repair that enables a shift away from historical discursive laagers and a reconfiguration of the narrative terrain within which conscripts narrate their identities. , Also known as: Edlmann, Theresa
- Full Text:
- Date Issued: 2015
Network simulation for professional audio networks
- Authors: Otten, Fred
- Date: 2015
- Subjects: Sound engineers , Ethernet (Local area network system) , Computer networks , Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4713 , http://hdl.handle.net/10962/d1017935
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet AVB. Bandwidth utilisation and parameter groupings are among the factors which need to be considered in these designs. An implementation of an extensible, generic simulation framework would allow audio engineers to easily compare protocols and networking technologies and get near real time responses with regards to bandwidth utilisation. Our hypothesis is that an application-level capability can be developed which uses a network simulation framework to enable this process and enhances the audio engineer’s experience of designing and configuring a network. This thesis presents a new, extensible simulation framework which can be utilised to simulate professional audio networks. This framework is utilised to develop an application - AudioNetSim - based on the requirements of an audio engineer. The thesis describes the AudioNetSim models and implementations for Ethernet AVB, Firewire and the AES- 64 control protocol. AudioNetSim enables bandwidth usage determination for any network configuration and connection scenario and is used to compare Firewire and Ethernet AVB bandwidth utilisation. It also applies graph theory to the circular join problem and provides a solution to detect circular joins.
- Full Text:
- Date Issued: 2015
- Authors: Otten, Fred
- Date: 2015
- Subjects: Sound engineers , Ethernet (Local area network system) , Computer networks , Computer simulation
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4713 , http://hdl.handle.net/10962/d1017935
- Description: Audio Engineers are required to design and deploy large multi-channel sound systems which meet a set of requirements and use networking technologies such as Firewire and Ethernet AVB. Bandwidth utilisation and parameter groupings are among the factors which need to be considered in these designs. An implementation of an extensible, generic simulation framework would allow audio engineers to easily compare protocols and networking technologies and get near real time responses with regards to bandwidth utilisation. Our hypothesis is that an application-level capability can be developed which uses a network simulation framework to enable this process and enhances the audio engineer’s experience of designing and configuring a network. This thesis presents a new, extensible simulation framework which can be utilised to simulate professional audio networks. This framework is utilised to develop an application - AudioNetSim - based on the requirements of an audio engineer. The thesis describes the AudioNetSim models and implementations for Ethernet AVB, Firewire and the AES- 64 control protocol. AudioNetSim enables bandwidth usage determination for any network configuration and connection scenario and is used to compare Firewire and Ethernet AVB bandwidth utilisation. It also applies graph theory to the circular join problem and provides a solution to detect circular joins.
- Full Text:
- Date Issued: 2015
Neurocognitive effects of head and body collisions on club level rugby union players
- Authors: Zoccola, Diana
- Date: 2015
- Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3257 , http://hdl.handle.net/10962/d1016397
- Description: The objective of the study was to investigate the cumulative neurocognitive effects of repetitive concussive and subconcussive events in club level Rugby Union (hereafter rugby) during the course of one rugby season, in a combined group and individualized case-based approach. Amateur adult club level rugby players (n = 20) were compared with a non-contact control group (n = 22) of equivalent age, years of education and estimated IQ (p = > .05, in all instances), although the two groups were clearly differentiated on the basis of a history of reported concussions (p = < .05). Video analyses documented the tackling maneuvers observed amongst the players during all matches across the rugby season revealing a sobering average of more than a thousand tackles per player, excluding any contact practice sessions. Five rugby players (n = 5) who were observed to have a head jarring event were also isolated for individualized postconcussive follow-up analysis of their neurocognitive profiles. Measures included the ImPACT Verbal and Visual Memory, Visual Motor Speed and Reaction Time composites and the Purdue Pegboard. Independent and dependent statistical analyses were employed to compare the rugby versus control group neurocognitive test profiles at and between the three test intervals. Correlational analyses explored the association between concussion, tackling and neurocognitive test outcomes. Descriptive comparisons of individual neurocognitive test scores with normative data were employed for the case analyses. Taken together, the results implicated vulnerability amongst club rugby players on the motor and speeded tasks, with less robust indications on the memory tasks. While limited in terms of its small sample size, it is considered that the outcome of the study was rendered more robust by virtue of being methodologically multifaceted with heuristic implications for future research studies in the area. The novel inclusion of tackling data as well as fine-tuned case analyses, were of particular relevance in that regard. The results add to a growing body of literature that implicates deleterious neurocognitive effects in participants of a sport such as rugby due to repetitive head jarring incidents that are intrinsic to the game.
- Full Text:
- Date Issued: 2015
- Authors: Zoccola, Diana
- Date: 2015
- Subjects: Head -- Wounds and injuries -- Psychology , Neuropsychological tests , Head -- Wounds and injuries , Sports injuries -- Psychological aspects
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:3257 , http://hdl.handle.net/10962/d1016397
- Description: The objective of the study was to investigate the cumulative neurocognitive effects of repetitive concussive and subconcussive events in club level Rugby Union (hereafter rugby) during the course of one rugby season, in a combined group and individualized case-based approach. Amateur adult club level rugby players (n = 20) were compared with a non-contact control group (n = 22) of equivalent age, years of education and estimated IQ (p = > .05, in all instances), although the two groups were clearly differentiated on the basis of a history of reported concussions (p = < .05). Video analyses documented the tackling maneuvers observed amongst the players during all matches across the rugby season revealing a sobering average of more than a thousand tackles per player, excluding any contact practice sessions. Five rugby players (n = 5) who were observed to have a head jarring event were also isolated for individualized postconcussive follow-up analysis of their neurocognitive profiles. Measures included the ImPACT Verbal and Visual Memory, Visual Motor Speed and Reaction Time composites and the Purdue Pegboard. Independent and dependent statistical analyses were employed to compare the rugby versus control group neurocognitive test profiles at and between the three test intervals. Correlational analyses explored the association between concussion, tackling and neurocognitive test outcomes. Descriptive comparisons of individual neurocognitive test scores with normative data were employed for the case analyses. Taken together, the results implicated vulnerability amongst club rugby players on the motor and speeded tasks, with less robust indications on the memory tasks. While limited in terms of its small sample size, it is considered that the outcome of the study was rendered more robust by virtue of being methodologically multifaceted with heuristic implications for future research studies in the area. The novel inclusion of tackling data as well as fine-tuned case analyses, were of particular relevance in that regard. The results add to a growing body of literature that implicates deleterious neurocognitive effects in participants of a sport such as rugby due to repetitive head jarring incidents that are intrinsic to the game.
- Full Text:
- Date Issued: 2015
Nonlinear optical studies of phthalocyanines and their conjugates with nanomaterials
- Authors: Sanusi, Sikiru Olukayode
- Date: 2015
- Subjects: Phthalocyanines , Nonlinear optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4545 , http://hdl.handle.net/10962/d1017925
- Description: A number of metallophthalocyanines (MPcs) and metal-free phthalocyanines (H₂Pcs) have been synthesized and characterized using various characterization tools such as ¹H-NMR, TOF mass spectrometry, FT-IR, UV-visible spectrophotometry and CHNS elemental analysis. Some of the MPcs were covalently linked to nanomaterials such as silica nanoparticles (SiNPs), single-walled carbon nanotubes (SWCNTs), magnetite nanoparticles (MNPs) and quantum dots (QDs), or embedded in polymer thin-films using poly(methyl methacrylate) (PMMA) and poly(acrylic acid) (PAA) as the polymer sources. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), thermogravimetry analysis and X-ray diffractometry. The nonlinear optical (NLO) properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. In general, most of the investigated MPcs showed good optical limiting behaviors, except for a few, like the non-peripherally-substituted 2-pyridyloxy phthalocyanines, which showed inhibited NLO response as a result of the ring-strain effects. The absence of a metal center was found to greatly reduce the inherent high nonlinearities expected of some of the phthalocyanine complexes. The octaphenoxy derivatives (61a – 61e) were found to exhibit reverse saturable absorption (RSA) that depends on the singlet-singlet transitions, hence making them less reliable optical limiters. The optical limiting properties of the MPcs were improved in the presence of nanomaterials such as the QDs, MNPs and SWCNTs, with MPc-QDs showing the best optical limiting behavior of the three. SiNPs have no significant effect on the optical limiting behavior of the MPcs. The optical limiting properties of the MPcs were greatly enhanced in the presence of PMMA or PAA polymers. The PAA polymer showed better optical limiting behavior compared to PMMA
- Full Text:
- Date Issued: 2015
- Authors: Sanusi, Sikiru Olukayode
- Date: 2015
- Subjects: Phthalocyanines , Nonlinear optics
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4545 , http://hdl.handle.net/10962/d1017925
- Description: A number of metallophthalocyanines (MPcs) and metal-free phthalocyanines (H₂Pcs) have been synthesized and characterized using various characterization tools such as ¹H-NMR, TOF mass spectrometry, FT-IR, UV-visible spectrophotometry and CHNS elemental analysis. Some of the MPcs were covalently linked to nanomaterials such as silica nanoparticles (SiNPs), single-walled carbon nanotubes (SWCNTs), magnetite nanoparticles (MNPs) and quantum dots (QDs), or embedded in polymer thin-films using poly(methyl methacrylate) (PMMA) and poly(acrylic acid) (PAA) as the polymer sources. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), thermogravimetry analysis and X-ray diffractometry. The nonlinear optical (NLO) properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. In general, most of the investigated MPcs showed good optical limiting behaviors, except for a few, like the non-peripherally-substituted 2-pyridyloxy phthalocyanines, which showed inhibited NLO response as a result of the ring-strain effects. The absence of a metal center was found to greatly reduce the inherent high nonlinearities expected of some of the phthalocyanine complexes. The octaphenoxy derivatives (61a – 61e) were found to exhibit reverse saturable absorption (RSA) that depends on the singlet-singlet transitions, hence making them less reliable optical limiters. The optical limiting properties of the MPcs were improved in the presence of nanomaterials such as the QDs, MNPs and SWCNTs, with MPc-QDs showing the best optical limiting behavior of the three. SiNPs have no significant effect on the optical limiting behavior of the MPcs. The optical limiting properties of the MPcs were greatly enhanced in the presence of PMMA or PAA polymers. The PAA polymer showed better optical limiting behavior compared to PMMA
- Full Text:
- Date Issued: 2015
On the characterisation of diffused light and optical elements in high concentrator photovoltaic modules
- Authors: Schultz, Ross Dane
- Date: 2015
- Subjects: Photovoltaic cells , Solar concentrators , Optical materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5170 , vital:20817
- Description: High Concentrated Photovoltaics (H-CPV) promise a more efficient, higher power output than traditional photovoltaic modules. This is achieved by concentrating sunlight onto a small triple junction (CTJ) InGaP/InGaAs/Ge cell (ranging from 3.14 mm2 to 1 cm2) by using precision optical systems. These systems utilise non-imaging optics to concentrate and distribute the incident solar flux uniformly onto the CTJ device receiver to achieve maximum performance and power output from an H-CPV module. However, the performance of the device can be reduced due to the partial or complete absorption of a range of wavelengths present in the solar spectrum by the optical materials that are used for concentration. An investigation to determine the current density topographies of each subcell in a CTJ cell by multiple raster scans of an optical fibre receiver of a spectrometer in the plane of the aperture of the secondary’s optical element was conducted. Results showed that the physical properties of the optical elements’ material absorbed different amounts of the spectral content with respect to the subcell photosensitive wavelength regions. The facet properties of the primary optical Fresnel lens showed that the more rounded the Fresnel facets were, the lower the concentration of sunlight incident onto the CTJ cell. The increase in facet numbers showed an increase in scattering of the incident sunlight and chromatic aberrations. Chromatic aberration created by the refractive optics showed a variation in the amount of concentration on each individual subcell as well as the difference in intensity profiles across for the different subcells. Based on these results and the development of new multi-junction devices by industry, the performance of a four and six-junction device with the optical materials was investigated by simulations. The simulations showed that the careful integration of an additional subcell in a multi-junction device could rectify current mismatch between the subcells in the device. Based on the simulations, the best performing multi-junction cell was identified as the four-junction device that showed a cell and module efficiency under operation of 42.5 % and 35.5 %, respectively. Additionally, based on the performance results observed from the H-CPV module, the development of an HCPV module that would attempt to harness the incident tracked diffuse sunlight available to a concentrator photovoltaic (CPV) module for additional energy yield was undertaken. The part of the study comprised of measurements of the solar source, design of a prototype Hybrid High Concentrator Photovoltaic (HH-CPV) module. Results showed that power generation from the H-CPV system was highly dependent on the DNI levels and fluctuates greatly with variation in the DNI. The irradiance levels within the diffuse regions of the H-CPV module showed that the baseplate and vertical sides had an average irradiance range of 140-450 and 50-225 W.m-2, respectively. Irradiance topographic raster scans revealed that the baseplate and vertical sides had a relatively uniform intensity distribution and was identified as favourable sites for diffuse cell population. Simulations of various PV technologies showed the most suitable technology for the placement within the cavity of the HH-CPV module. The developed HH-CPV module was finalized with the utilization of CIS modules to harness the diffuse irradiance. During a 3 month power monitoring of the HH-CPV system, it was determined that the major power generation for the HH-CPV module come from the CPV component, while the CIS modules showed a minor power contribution. The total energy yield for the monitoring period was 45.99, 3.89 and 1.76 kW.h for the CPV, four-vertical sides and baseplate components, respectively. The increase in energy yield of the HH-CPV module when compared to the standard H-CPV module was determined to be 12.35 % for the monitoring period. The incorporation of the CIS modules into the H-CPV module to create the HH-CPV module did increase the energy yield of the module during high DNI conditions and did offset the almost zero power generation during low DNI conditions.
- Full Text:
- Date Issued: 2015
- Authors: Schultz, Ross Dane
- Date: 2015
- Subjects: Photovoltaic cells , Solar concentrators , Optical materials
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/5170 , vital:20817
- Description: High Concentrated Photovoltaics (H-CPV) promise a more efficient, higher power output than traditional photovoltaic modules. This is achieved by concentrating sunlight onto a small triple junction (CTJ) InGaP/InGaAs/Ge cell (ranging from 3.14 mm2 to 1 cm2) by using precision optical systems. These systems utilise non-imaging optics to concentrate and distribute the incident solar flux uniformly onto the CTJ device receiver to achieve maximum performance and power output from an H-CPV module. However, the performance of the device can be reduced due to the partial or complete absorption of a range of wavelengths present in the solar spectrum by the optical materials that are used for concentration. An investigation to determine the current density topographies of each subcell in a CTJ cell by multiple raster scans of an optical fibre receiver of a spectrometer in the plane of the aperture of the secondary’s optical element was conducted. Results showed that the physical properties of the optical elements’ material absorbed different amounts of the spectral content with respect to the subcell photosensitive wavelength regions. The facet properties of the primary optical Fresnel lens showed that the more rounded the Fresnel facets were, the lower the concentration of sunlight incident onto the CTJ cell. The increase in facet numbers showed an increase in scattering of the incident sunlight and chromatic aberrations. Chromatic aberration created by the refractive optics showed a variation in the amount of concentration on each individual subcell as well as the difference in intensity profiles across for the different subcells. Based on these results and the development of new multi-junction devices by industry, the performance of a four and six-junction device with the optical materials was investigated by simulations. The simulations showed that the careful integration of an additional subcell in a multi-junction device could rectify current mismatch between the subcells in the device. Based on the simulations, the best performing multi-junction cell was identified as the four-junction device that showed a cell and module efficiency under operation of 42.5 % and 35.5 %, respectively. Additionally, based on the performance results observed from the H-CPV module, the development of an HCPV module that would attempt to harness the incident tracked diffuse sunlight available to a concentrator photovoltaic (CPV) module for additional energy yield was undertaken. The part of the study comprised of measurements of the solar source, design of a prototype Hybrid High Concentrator Photovoltaic (HH-CPV) module. Results showed that power generation from the H-CPV system was highly dependent on the DNI levels and fluctuates greatly with variation in the DNI. The irradiance levels within the diffuse regions of the H-CPV module showed that the baseplate and vertical sides had an average irradiance range of 140-450 and 50-225 W.m-2, respectively. Irradiance topographic raster scans revealed that the baseplate and vertical sides had a relatively uniform intensity distribution and was identified as favourable sites for diffuse cell population. Simulations of various PV technologies showed the most suitable technology for the placement within the cavity of the HH-CPV module. The developed HH-CPV module was finalized with the utilization of CIS modules to harness the diffuse irradiance. During a 3 month power monitoring of the HH-CPV system, it was determined that the major power generation for the HH-CPV module come from the CPV component, while the CIS modules showed a minor power contribution. The total energy yield for the monitoring period was 45.99, 3.89 and 1.76 kW.h for the CPV, four-vertical sides and baseplate components, respectively. The increase in energy yield of the HH-CPV module when compared to the standard H-CPV module was determined to be 12.35 % for the monitoring period. The incorporation of the CIS modules into the H-CPV module to create the HH-CPV module did increase the energy yield of the module during high DNI conditions and did offset the almost zero power generation during low DNI conditions.
- Full Text:
- Date Issued: 2015
On the characterisation of solar cells using light beam induced current measurements
- Authors: Kwarikunda, Nicholas
- Date: 2015
- Subjects: Solor cells Spectrum, Solar
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11147 , vital:26889
- Description: The presence of inhomogeneities in semiconductor materials used to fabricate solar cell devices may result in spatial non uniformities in the device properties which may affect current generation in these devices. Besides, current reducing defects such as inclusions, local shunts and optical blockages may be introduced during the various device manufacturing processes which may adversely affect the performance and overall efficiency of solar cells. Diagnostic techniques are therefore needed to identify these defects so as to improve the production technology. This thesis presents the Light Beam Induced Current (LBIC) technique for mapping spatial non uniformities in solar cell devices. The LBIC is a non destructive characterisation technique that uses a focused light beam to raster scan a solar cell surface as the photo-generated current is recorded as a function of position to generate a photo-response map. The technique was used to obtain photoresponse maps for a mc-Si, Back contact Back junction (BC-BJ) silicon solar cell and the InGaP/InGaAs/Ge concentrating triple junction (CTJ) solar cell from which various local current reducing defects were mapped. A reflection signal detector was incorporated into the LBIC measurement system to enable us distinguish between optical blockages on the cell surface and current reducing defects within the solar cell devices. By dynamically biasing the solar cell devices, the electrical activity of the identified defects was investigated and also point-by-point current-voltage (I-V) characteristics were obtained. An interval division algorithm was applied to the measured point-by-point I-V characteristics to extract device and performance parameters from which device and performance parameter uniformity of the devices were mapped. Dark and full cell solar illumination I-V characteristics were also measured to extract device parameters. Analysis of extracted parameters revealed differences between extracted dark and illuminated device parameters which was attributed to departure from the superposition principle due to non-linearity of the semiconductor device equations with respect to carrier concentration. An investigation into the effect of illumination intensity on the I-V parameters of a spot illuminated BC-BJ Si solar cell showed a linear increase and a logarithmic increase of the short circuit current and open circuit voltage respectively with intensity while the series resistance decreased with intensity, which was attributed to increase in conductivity of the active layer. The ideality factor and saturation current were observed to increase while the shunt resistance initially increased before decreasing at higher intensity levels. Under monochromatic illumination, the photo-response of the BC-BJ Si cell was higher at 785nm than at 445nm due to low absorption coefficient of Si for longer wavelength radiations, resulting in carrier generation within the bulk, where there is a higher probability of carriers being collected at the p-n junction before they recombine. Under solar illumination, as the spectral content was altered using long pass colour filters with cut off wavelengths of 610nm and 1000nm, the performance parameters were observed to decrease and this was mainly due to decrease in intensity. For the CTJ solar cell, however, blocking of radiations below 610nm resulted in current mismatch that severely degraded the short circuit current (Isc). The current mismatch affected the extracted device and performance parameters. With a 1000nm long pass filter, a dark I-V was obtained since only the bottom Ge subcell was activated.
- Full Text:
- Date Issued: 2015
- Authors: Kwarikunda, Nicholas
- Date: 2015
- Subjects: Solor cells Spectrum, Solar
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10948/11147 , vital:26889
- Description: The presence of inhomogeneities in semiconductor materials used to fabricate solar cell devices may result in spatial non uniformities in the device properties which may affect current generation in these devices. Besides, current reducing defects such as inclusions, local shunts and optical blockages may be introduced during the various device manufacturing processes which may adversely affect the performance and overall efficiency of solar cells. Diagnostic techniques are therefore needed to identify these defects so as to improve the production technology. This thesis presents the Light Beam Induced Current (LBIC) technique for mapping spatial non uniformities in solar cell devices. The LBIC is a non destructive characterisation technique that uses a focused light beam to raster scan a solar cell surface as the photo-generated current is recorded as a function of position to generate a photo-response map. The technique was used to obtain photoresponse maps for a mc-Si, Back contact Back junction (BC-BJ) silicon solar cell and the InGaP/InGaAs/Ge concentrating triple junction (CTJ) solar cell from which various local current reducing defects were mapped. A reflection signal detector was incorporated into the LBIC measurement system to enable us distinguish between optical blockages on the cell surface and current reducing defects within the solar cell devices. By dynamically biasing the solar cell devices, the electrical activity of the identified defects was investigated and also point-by-point current-voltage (I-V) characteristics were obtained. An interval division algorithm was applied to the measured point-by-point I-V characteristics to extract device and performance parameters from which device and performance parameter uniformity of the devices were mapped. Dark and full cell solar illumination I-V characteristics were also measured to extract device parameters. Analysis of extracted parameters revealed differences between extracted dark and illuminated device parameters which was attributed to departure from the superposition principle due to non-linearity of the semiconductor device equations with respect to carrier concentration. An investigation into the effect of illumination intensity on the I-V parameters of a spot illuminated BC-BJ Si solar cell showed a linear increase and a logarithmic increase of the short circuit current and open circuit voltage respectively with intensity while the series resistance decreased with intensity, which was attributed to increase in conductivity of the active layer. The ideality factor and saturation current were observed to increase while the shunt resistance initially increased before decreasing at higher intensity levels. Under monochromatic illumination, the photo-response of the BC-BJ Si cell was higher at 785nm than at 445nm due to low absorption coefficient of Si for longer wavelength radiations, resulting in carrier generation within the bulk, where there is a higher probability of carriers being collected at the p-n junction before they recombine. Under solar illumination, as the spectral content was altered using long pass colour filters with cut off wavelengths of 610nm and 1000nm, the performance parameters were observed to decrease and this was mainly due to decrease in intensity. For the CTJ solar cell, however, blocking of radiations below 610nm resulted in current mismatch that severely degraded the short circuit current (Isc). The current mismatch affected the extracted device and performance parameters. With a 1000nm long pass filter, a dark I-V was obtained since only the bottom Ge subcell was activated.
- Full Text:
- Date Issued: 2015
Organizational culture in the South African construction industry : effects on work-life balance and individual performance
- Dlamini, Gcebekile Tikhokhile
- Authors: Dlamini, Gcebekile Tikhokhile
- Date: 2015
- Subjects: Construction industry -- South Africa , Work-life balance -- South Africa , Corporate culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9702 , http://hdl.handle.net/10948/d1018513
- Description: The South African construction industry plays an important role in the economy and overall development of the country, with respect to its total fiscal contribution and the total number of people who are employed. In addition, it is a major contributor to infrastructure development. However, the human resource base within this industry is confronted with a plethora of challenges that are inherent to the construction industry. These manifest themselves in stressful working conditions and long working hours, labour intensive jobs, reduced job security due to job losses and short-term projects, and the feeble health and safety (H&S) standards. Together with a variety of socio-economic and political issues, these challenges form a perceived and broad organisational culture of this industry, which impacts on the industry‟s productivity. As construction management efforts in the development of the human resources base increase, the industry recognises that work-life balance is an important and critical issue in the 21st century. Construction management is a discipline that embodies two interdependent dimensions; the management of the business of construction and the management of projects. Of the latter, the key principles thereof are, as part of a management strategy, planning, organizing, leading, controlling and coordinating projects. To achieve these strategic components, an effective human resource base is required. Work-life balance is therefore a management issue and organizational culture sets a backdrop from which it can be understood. This study focused on the status of the organisational culture of the production establishments that form part of the construction industry and the manner in which it manifests on the work-life balance of the workers. Furthermore, the correlation between work-life balance and individual work performance was examined. An exploratory research approach was adopted and the research technique followed an interview protocol. The main findings demonstrate that the South African construction industry is predominantly a clan culture with minor characteristics of the hierarchy, adhocracy and market cultures. Furthermore, work-life balance is difficult to attain and it influences individual work performance. The main conclusion is that organizational culture in construction firms is imbalanced. Thus, the main recommendation is that the industry adopts a balanced organizational culture and modern human resource practices.
- Full Text:
- Date Issued: 2015
- Authors: Dlamini, Gcebekile Tikhokhile
- Date: 2015
- Subjects: Construction industry -- South Africa , Work-life balance -- South Africa , Corporate culture -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:9702 , http://hdl.handle.net/10948/d1018513
- Description: The South African construction industry plays an important role in the economy and overall development of the country, with respect to its total fiscal contribution and the total number of people who are employed. In addition, it is a major contributor to infrastructure development. However, the human resource base within this industry is confronted with a plethora of challenges that are inherent to the construction industry. These manifest themselves in stressful working conditions and long working hours, labour intensive jobs, reduced job security due to job losses and short-term projects, and the feeble health and safety (H&S) standards. Together with a variety of socio-economic and political issues, these challenges form a perceived and broad organisational culture of this industry, which impacts on the industry‟s productivity. As construction management efforts in the development of the human resources base increase, the industry recognises that work-life balance is an important and critical issue in the 21st century. Construction management is a discipline that embodies two interdependent dimensions; the management of the business of construction and the management of projects. Of the latter, the key principles thereof are, as part of a management strategy, planning, organizing, leading, controlling and coordinating projects. To achieve these strategic components, an effective human resource base is required. Work-life balance is therefore a management issue and organizational culture sets a backdrop from which it can be understood. This study focused on the status of the organisational culture of the production establishments that form part of the construction industry and the manner in which it manifests on the work-life balance of the workers. Furthermore, the correlation between work-life balance and individual work performance was examined. An exploratory research approach was adopted and the research technique followed an interview protocol. The main findings demonstrate that the South African construction industry is predominantly a clan culture with minor characteristics of the hierarchy, adhocracy and market cultures. Furthermore, work-life balance is difficult to attain and it influences individual work performance. The main conclusion is that organizational culture in construction firms is imbalanced. Thus, the main recommendation is that the industry adopts a balanced organizational culture and modern human resource practices.
- Full Text:
- Date Issued: 2015
Performing whiteness; representing otherness : Hugh Tracey and African music
- Authors: Coetzee, Paulette June
- Date: 2015
- Subjects: Tracey, Hugh , Music -- Africa , International Library of African Music , Ethnomusicology -- Africa , Ethnomusicologists -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2327 , http://hdl.handle.net/10962/d1016502
- Description: This thesis provides a critical study of texts associated with Hugh Tracey (1903–1977). Tracey is well-known for his work in African music studies, particularly for his major contribution to the recorded archive of musical sound in sub-Saharan Africa and his founding of the International Library of African Music (ILAM) in 1954. My reading of him is informed by a postcolonial perspective, whiteness studies and African scholarship on ways in which constructions of African identity and tradition have been shaped by the colonial archive. In my view, Tracey was part of a mid-twentieth century movement which sought to marshal positive representations of traditional African culture in the interest of maintaining and strengthening colonial rule. While his recording project may have fostered inclusion through creating spaces for indigenous musicians to be heard, it also functioned to promote racist exclusion in the manner of its production, distribution and claims to expertise. Moreover, his initial strategy for ILAM’s sustainability targeted colonial government and industry as primary clients, with the promise that promoting traditional music as a means of entertainment and self-expression for black subjects and workers would ease administration and reduce conflict. I believe that it is important to acknowledge and interrogate the problematic racial attitudes and practices associated with the history of Tracey’s archive – not to undermine its significance in any way but to allow it to be better understood and used more productively in the future.
- Full Text:
- Date Issued: 2015
- Authors: Coetzee, Paulette June
- Date: 2015
- Subjects: Tracey, Hugh , Music -- Africa , International Library of African Music , Ethnomusicology -- Africa , Ethnomusicologists -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2327 , http://hdl.handle.net/10962/d1016502
- Description: This thesis provides a critical study of texts associated with Hugh Tracey (1903–1977). Tracey is well-known for his work in African music studies, particularly for his major contribution to the recorded archive of musical sound in sub-Saharan Africa and his founding of the International Library of African Music (ILAM) in 1954. My reading of him is informed by a postcolonial perspective, whiteness studies and African scholarship on ways in which constructions of African identity and tradition have been shaped by the colonial archive. In my view, Tracey was part of a mid-twentieth century movement which sought to marshal positive representations of traditional African culture in the interest of maintaining and strengthening colonial rule. While his recording project may have fostered inclusion through creating spaces for indigenous musicians to be heard, it also functioned to promote racist exclusion in the manner of its production, distribution and claims to expertise. Moreover, his initial strategy for ILAM’s sustainability targeted colonial government and industry as primary clients, with the promise that promoting traditional music as a means of entertainment and self-expression for black subjects and workers would ease administration and reduce conflict. I believe that it is important to acknowledge and interrogate the problematic racial attitudes and practices associated with the history of Tracey’s archive – not to undermine its significance in any way but to allow it to be better understood and used more productively in the future.
- Full Text:
- Date Issued: 2015
Photophysical studies of Zinc phthalocyanine-silica nanoparticles conjugates
- Authors: Fashina, Adedayo
- Date: 2015
- Subjects: Nanoparticles , Phthalocyanines , Zinc , Silica , Photochemistry , Adsorption
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4537 , http://hdl.handle.net/10962/d1017917
- Description: This thesis reports on the synthesis and characterization of both symmetrical and asymmetrical Zinc phthalocyanine complexes. The complexes contained groups such as carboxylic, amino and alkyne for covalent grafting to the surface of silica nanoparticles. The use of symmetrical and asymmetrical complexes was geared towards comparing the non-specific binding of the symmetrical complexes to the specific binding observed in the asymmetrical complexes. The complexes were also doped within the silica matrix and compared to the surface grafted conjugates. The complexes and the conjugates were well characterized with a variety of techniques. The fluorescence lifetimes of the phthalocyanine complexes containing either terminal carboxylic groups or an alkyne group showed a mono-exponential decay while the amino containing phthalocyanine complexes gave a bi-exponential decay. A similar trend was observed for their respective conjugates. Some of the conjugates of the asymmetrical complexes showed a decrease in fluorescence lifetimes and a corresponding decrease in fluorescence quantum yields. The fluorescence quantum yields for all the symmetrical complexes studied showed either an improvement or retained the luminescence of the grafted phthalocyanine complex. Most of the conjugates showed a faster intersystem crossing time in comparison to the complexes alone. The grafted or doped conjugates containing symmetrical phthalocyanine complexes with carboxyl groups showed improvements both in fluorescence and triplet quantum yields. All the conjugates except two showed an increase in triplet lifetimes when compared to their respective phthalocyanine complexes. Optical nonlinearities of nine of the phthalocyanine complexes were studied and all the complexes showed characteristic reverse saturable absorption behavior. Complex 10 showed the most promising optical limiting behavior. The aggregation and dissolution studies of the conjugates were also carried out in a simulated biological medium and the silicon level detected was noticed to have increased with incubation time.
- Full Text:
- Date Issued: 2015
- Authors: Fashina, Adedayo
- Date: 2015
- Subjects: Nanoparticles , Phthalocyanines , Zinc , Silica , Photochemistry , Adsorption
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4537 , http://hdl.handle.net/10962/d1017917
- Description: This thesis reports on the synthesis and characterization of both symmetrical and asymmetrical Zinc phthalocyanine complexes. The complexes contained groups such as carboxylic, amino and alkyne for covalent grafting to the surface of silica nanoparticles. The use of symmetrical and asymmetrical complexes was geared towards comparing the non-specific binding of the symmetrical complexes to the specific binding observed in the asymmetrical complexes. The complexes were also doped within the silica matrix and compared to the surface grafted conjugates. The complexes and the conjugates were well characterized with a variety of techniques. The fluorescence lifetimes of the phthalocyanine complexes containing either terminal carboxylic groups or an alkyne group showed a mono-exponential decay while the amino containing phthalocyanine complexes gave a bi-exponential decay. A similar trend was observed for their respective conjugates. Some of the conjugates of the asymmetrical complexes showed a decrease in fluorescence lifetimes and a corresponding decrease in fluorescence quantum yields. The fluorescence quantum yields for all the symmetrical complexes studied showed either an improvement or retained the luminescence of the grafted phthalocyanine complex. Most of the conjugates showed a faster intersystem crossing time in comparison to the complexes alone. The grafted or doped conjugates containing symmetrical phthalocyanine complexes with carboxyl groups showed improvements both in fluorescence and triplet quantum yields. All the conjugates except two showed an increase in triplet lifetimes when compared to their respective phthalocyanine complexes. Optical nonlinearities of nine of the phthalocyanine complexes were studied and all the complexes showed characteristic reverse saturable absorption behavior. Complex 10 showed the most promising optical limiting behavior. The aggregation and dissolution studies of the conjugates were also carried out in a simulated biological medium and the silicon level detected was noticed to have increased with incubation time.
- Full Text:
- Date Issued: 2015
Photophysicochemical properties and in vitro photodynamic therapy activities of zinc phthalocyanine conjugates with biomolecules and single-walled carbon nanotubes
- Authors: Ogbodu, Racheal O
- Date: 2015
- Subjects: Photochemotherapy , Phthalocyanines , Biomolecules
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4544 , http://hdl.handle.net/10962/d1017924
- Description: The synthesis, photophysicochemcial properties, in vitro dark toxicity and photodynamic therapy (PDT) activities of different derivatives of zinc phthalocyanine (ZnPc) conjugates with biomolecules (folic acid, bovine serum albumin (BSA), ascorbic acid, uridine or spermine) and single-walled carbon nanotubes (SWCNTs) are presented in this work. The fluorescence quantum yields (ΦF) (Subscript F) of the ZnPc derivatives or ZnPc-biomolecule conjugates remained relatively the same as compared to the precursor Pcs. Slight increases were observed in the ΦF (Subscript F) values of conjugates containing substituents such as pyrene, folic acid or BSA with intrinsic fluorescence properties. The triplet quantum yield (ΦT ) (Subscript T) values for some ZnPc conjugates increases compared to the precursor ZnPcs due to extended π conjugation (for the conjugate with pyrene) and the presence of phenyl ring that support spin-orbit charge transfer intersystem crossing to triplet state. While some conjugates showed decreases in the ΦT (Subscript T) values compared to precursor ZnPcs due to the presence of substituents that could quench photo-excited state properties. The singlet oxygen quantum yield (ΦΔ ) values follow the trends of the triplet quantum yield values. The conjugates containing BSA also show increases in the ΦΔ values without corresponding increases in ΦT (Subscript T) values due to the ability of BSA to generate free radicals including singlet oxygen. The presence of SWCNTs decreases the photophysicochemcial properties of some ZnPc-SWCNT conjugates compared to the precursor ZnPcs due to photo-induced electron transfer from an excited Pc complex (electron donor) to SWCNTs (electron acceptor). However, increases were observed in some ZnPc-SWCNT conjugates as a result of fast charge recombination process due to highly short-lived radical ion pair produced. These phenomena affected the ΦF (Suscript F) values, ΦT (Suscript T) values, and the ΦΔ values. Increases or decreases in ΦT (Suscript T) values resulted in corresponding increases or decreases in ΦΔ values
- Full Text:
- Date Issued: 2015
- Authors: Ogbodu, Racheal O
- Date: 2015
- Subjects: Photochemotherapy , Phthalocyanines , Biomolecules
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4544 , http://hdl.handle.net/10962/d1017924
- Description: The synthesis, photophysicochemcial properties, in vitro dark toxicity and photodynamic therapy (PDT) activities of different derivatives of zinc phthalocyanine (ZnPc) conjugates with biomolecules (folic acid, bovine serum albumin (BSA), ascorbic acid, uridine or spermine) and single-walled carbon nanotubes (SWCNTs) are presented in this work. The fluorescence quantum yields (ΦF) (Subscript F) of the ZnPc derivatives or ZnPc-biomolecule conjugates remained relatively the same as compared to the precursor Pcs. Slight increases were observed in the ΦF (Subscript F) values of conjugates containing substituents such as pyrene, folic acid or BSA with intrinsic fluorescence properties. The triplet quantum yield (ΦT ) (Subscript T) values for some ZnPc conjugates increases compared to the precursor ZnPcs due to extended π conjugation (for the conjugate with pyrene) and the presence of phenyl ring that support spin-orbit charge transfer intersystem crossing to triplet state. While some conjugates showed decreases in the ΦT (Subscript T) values compared to precursor ZnPcs due to the presence of substituents that could quench photo-excited state properties. The singlet oxygen quantum yield (ΦΔ ) values follow the trends of the triplet quantum yield values. The conjugates containing BSA also show increases in the ΦΔ values without corresponding increases in ΦT (Subscript T) values due to the ability of BSA to generate free radicals including singlet oxygen. The presence of SWCNTs decreases the photophysicochemcial properties of some ZnPc-SWCNT conjugates compared to the precursor ZnPcs due to photo-induced electron transfer from an excited Pc complex (electron donor) to SWCNTs (electron acceptor). However, increases were observed in some ZnPc-SWCNT conjugates as a result of fast charge recombination process due to highly short-lived radical ion pair produced. These phenomena affected the ΦF (Suscript F) values, ΦT (Suscript T) values, and the ΦΔ values. Increases or decreases in ΦT (Suscript T) values resulted in corresponding increases or decreases in ΦΔ values
- Full Text:
- Date Issued: 2015
Phthalocyanine-nanoparticle conjugates for photodynamic therapy of cancer and phototransformation of organic pollutants
- Authors: Khoza, Phindile Brenda
- Date: 2015
- Subjects: Phthalocyanines , Nanoparticles , Photochemotherapy , Cancer -- Chemotherapy , Zinc oxide , Photocatalysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4538 , http://hdl.handle.net/10962/d1017918
- Description: The synthesis and extensive spectroscopical characterization of novel phthalocyanines are reported. The new compounds were characterized by elemental analysis, FT-IR, ¹HNMR, mass spectrometry and UV–Vis spectroscopy. The new phthalocyanines showed remarkable photophysicochemical behaviour. The novel phthalocyanines were then conjugated to nanoparticles, silver and ZnO. The coupling of the novel Pcs to nanoparticles was through covalent bonding and ligand exchange. These conjugates were supported onto electrospun polystyrene fibers and chitosan microbeads for use as photocatalysts. The efficiency of the immobilized Pcs and Pc-nanoparticles was assessed by the phototrasfromation of organic pollutants, methyl orange and Rhodamine 6G as model dyes. Upon conjugating phthalocyanines to nanoparticles, there was a great increase in the rate of photodegradation of the model dyes. The photodynamic activity of the novel phthalocyanines upon conjugating to nanoparticles and selected targeting agents is also reported. The targeting agents employed in this study are folic acid and polylysine. Conjugating the phthalocyanines to folic acid or polylysine improved the solubility of the phthalocyanines in aqueous media. The potency of the conjugates was investigated on breast (MCF-7), prostate and melanoma cancer cell lines. The phthalocyanines showed no toxicity in the absence of light. However, upon illumination, a concentration dependent cellular decrease was observed.
- Full Text:
- Date Issued: 2015
- Authors: Khoza, Phindile Brenda
- Date: 2015
- Subjects: Phthalocyanines , Nanoparticles , Photochemotherapy , Cancer -- Chemotherapy , Zinc oxide , Photocatalysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4538 , http://hdl.handle.net/10962/d1017918
- Description: The synthesis and extensive spectroscopical characterization of novel phthalocyanines are reported. The new compounds were characterized by elemental analysis, FT-IR, ¹HNMR, mass spectrometry and UV–Vis spectroscopy. The new phthalocyanines showed remarkable photophysicochemical behaviour. The novel phthalocyanines were then conjugated to nanoparticles, silver and ZnO. The coupling of the novel Pcs to nanoparticles was through covalent bonding and ligand exchange. These conjugates were supported onto electrospun polystyrene fibers and chitosan microbeads for use as photocatalysts. The efficiency of the immobilized Pcs and Pc-nanoparticles was assessed by the phototrasfromation of organic pollutants, methyl orange and Rhodamine 6G as model dyes. Upon conjugating phthalocyanines to nanoparticles, there was a great increase in the rate of photodegradation of the model dyes. The photodynamic activity of the novel phthalocyanines upon conjugating to nanoparticles and selected targeting agents is also reported. The targeting agents employed in this study are folic acid and polylysine. Conjugating the phthalocyanines to folic acid or polylysine improved the solubility of the phthalocyanines in aqueous media. The potency of the conjugates was investigated on breast (MCF-7), prostate and melanoma cancer cell lines. The phthalocyanines showed no toxicity in the absence of light. However, upon illumination, a concentration dependent cellular decrease was observed.
- Full Text:
- Date Issued: 2015
Pitied plumage and dying birds : the public mourning of national heroines and post-apartheid foundational mythology construction
- Authors: Kerseboom, Simone
- Date: 2015
- Subjects: Women heroes -- South Africa , Nationalism -- South Africa , Nationalism and collective memory -- South Africa , Post-apartheid era -- South Africa , Women political activists -- South Africa , Dead -- Political aspects -- South Africa , Critical discourse analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2625 , http://hdl.handle.net/10962/d1019884
- Description: The original contribution of this thesis is the examination of the official construction of a post-apartheid foundation myth through the analysis of the dead body politics of five iconic South African women that spans the three presidencies that have defined South Africa’s democratic era. This thesis examines the death and funeral of Albertina Sisulu, the return and burial of Sara Baartman, and the commemoration of Charlotte Maxeke, Lilian Ngoyi, and Helen Joseph. Sisulu, Baartman, Maxeke, Ngoyi, and Joseph have been constructed as heroines and as foundational figures for the post-apartheid nation in official rhetoric. It will contend that the dead body politics of these women not only informs a new foundational mythology, but also features in the processes of regime legitimation when the ANC-dominated government faces strong societal criticism. Although such official expressions of nationalism may appear exhausted, this thesis will show that nationalism remains a powerful and dangerous force in South Africa that attempts to silence opposition and critical analysis of perceived failing government policies or inaction. This thesis will indicate that as women’s bodies and legacies are appropriated for nationalist projects they are subsumed in discourses of domestic femininity in official rhetoric that dangerously detract from women’s democratic rights and their ability to exercise responsible and productive citizenship in the post-apartheid state. It will argue that women’s historic political activism is contained within the meta-narrative of ‘The Struggle’ and that women are re-subsumed into the patriarchal discourses of the past that are inherited in the present. This thesis approaches this topic by considering a top-to-bottom construction of post-apartheid nationalism through applying feminist critical discourse analysis to official rhetoric articulated at the public mourning and commemorative rituals of these five women.
- Full Text:
- Date Issued: 2015
- Authors: Kerseboom, Simone
- Date: 2015
- Subjects: Women heroes -- South Africa , Nationalism -- South Africa , Nationalism and collective memory -- South Africa , Post-apartheid era -- South Africa , Women political activists -- South Africa , Dead -- Political aspects -- South Africa , Critical discourse analysis
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2625 , http://hdl.handle.net/10962/d1019884
- Description: The original contribution of this thesis is the examination of the official construction of a post-apartheid foundation myth through the analysis of the dead body politics of five iconic South African women that spans the three presidencies that have defined South Africa’s democratic era. This thesis examines the death and funeral of Albertina Sisulu, the return and burial of Sara Baartman, and the commemoration of Charlotte Maxeke, Lilian Ngoyi, and Helen Joseph. Sisulu, Baartman, Maxeke, Ngoyi, and Joseph have been constructed as heroines and as foundational figures for the post-apartheid nation in official rhetoric. It will contend that the dead body politics of these women not only informs a new foundational mythology, but also features in the processes of regime legitimation when the ANC-dominated government faces strong societal criticism. Although such official expressions of nationalism may appear exhausted, this thesis will show that nationalism remains a powerful and dangerous force in South Africa that attempts to silence opposition and critical analysis of perceived failing government policies or inaction. This thesis will indicate that as women’s bodies and legacies are appropriated for nationalist projects they are subsumed in discourses of domestic femininity in official rhetoric that dangerously detract from women’s democratic rights and their ability to exercise responsible and productive citizenship in the post-apartheid state. It will argue that women’s historic political activism is contained within the meta-narrative of ‘The Struggle’ and that women are re-subsumed into the patriarchal discourses of the past that are inherited in the present. This thesis approaches this topic by considering a top-to-bottom construction of post-apartheid nationalism through applying feminist critical discourse analysis to official rhetoric articulated at the public mourning and commemorative rituals of these five women.
- Full Text:
- Date Issued: 2015
Primary maths teacher learning and identity within a numeracy in-service community of practice
- Authors: Pausigere, Peter
- Date: 2015
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Teachers -- In-service training -- South Africa , Student-centered learning -- South Africa , Communities of practice -- South Africa , Educational change -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2019 , http://hdl.handle.net/10962/d1017183
- Description: This study focuses on the processes of primary maths teacher learning and how their identities and practices evolve in relation to participation in a primary maths focused in-service teacher education programme, called the Numeracy Inquiry Community of Leader Educators (NICLE).Additionally it investigates activities, relations and forms of participation within the Community of Practice (CoP) which enable or constrain evolving primary maths identities and practices and how these relate to the broader context. The study draws from the situative-participationists (Lave, 1996; Wenger, 1998; Sfard & Prusak, 2005; Wenger et al, 2002) theoretical framework supplemented by Bernstein’s (2000) pedagogic identity model. Using a qualitative educational interpretive approach I sampled 8 primary teachers drawn from NICLE and gathered data through participant observations, interactive interviews, document analysis and reflective journals. Analysing the key data themes that emerged from teacher learning stories, which I have called stelos, the study explains the nature of the primary maths teachers’ learning, transformation and participation experiences in NICLE using the synonyms reinvigoration and remediation and activation and relating these semantics to the teachers’ mathematical identities and histories. The study also explains the processes through which primary maths teacher identities evolve in relation to participation in an in-service CoP as ‘insiding’ and ‘outcropping’. Interpreting qualitative data from the empirical field indicates that teachers participating in NICLE mostly took-up into their maths classrooms key numeracy-domain concepts, resources and issues presented by primary maths experts which are informed by research and theory that link to practices. Teachers collaboratively and actively engaged in a range of activities that relate to classroom practices. Teacher learning was also enabled when teachers engaged in maths overlapping communities of practice, shared classroom experiences in friendly ways with fellow NICLE teachers and engaged with NICLE presenters who mutually respected and regarded them as professionals. Such affordances were said to enable teachers to engage learners in maths classes and improve their understanding of specific primary maths concepts. On the other hand teachers felt challenged by the travelling distance, limited time and also raised the tension of how to scale-up maths professional development initiatives to include schools from their community. The study makes a theoretical contribution by illustrating how Bernstein’s pedagogic identity model and its elaboration by Tyler (1999) provides analytical tools to interrogate macro educational changes and connect these to the micro processes and teacher identities.
- Full Text:
- Date Issued: 2015
- Authors: Pausigere, Peter
- Date: 2015
- Subjects: Mathematics -- Study and teaching (Elementary) -- South Africa , Teachers -- In-service training -- South Africa , Student-centered learning -- South Africa , Communities of practice -- South Africa , Educational change -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:2019 , http://hdl.handle.net/10962/d1017183
- Description: This study focuses on the processes of primary maths teacher learning and how their identities and practices evolve in relation to participation in a primary maths focused in-service teacher education programme, called the Numeracy Inquiry Community of Leader Educators (NICLE).Additionally it investigates activities, relations and forms of participation within the Community of Practice (CoP) which enable or constrain evolving primary maths identities and practices and how these relate to the broader context. The study draws from the situative-participationists (Lave, 1996; Wenger, 1998; Sfard & Prusak, 2005; Wenger et al, 2002) theoretical framework supplemented by Bernstein’s (2000) pedagogic identity model. Using a qualitative educational interpretive approach I sampled 8 primary teachers drawn from NICLE and gathered data through participant observations, interactive interviews, document analysis and reflective journals. Analysing the key data themes that emerged from teacher learning stories, which I have called stelos, the study explains the nature of the primary maths teachers’ learning, transformation and participation experiences in NICLE using the synonyms reinvigoration and remediation and activation and relating these semantics to the teachers’ mathematical identities and histories. The study also explains the processes through which primary maths teacher identities evolve in relation to participation in an in-service CoP as ‘insiding’ and ‘outcropping’. Interpreting qualitative data from the empirical field indicates that teachers participating in NICLE mostly took-up into their maths classrooms key numeracy-domain concepts, resources and issues presented by primary maths experts which are informed by research and theory that link to practices. Teachers collaboratively and actively engaged in a range of activities that relate to classroom practices. Teacher learning was also enabled when teachers engaged in maths overlapping communities of practice, shared classroom experiences in friendly ways with fellow NICLE teachers and engaged with NICLE presenters who mutually respected and regarded them as professionals. Such affordances were said to enable teachers to engage learners in maths classes and improve their understanding of specific primary maths concepts. On the other hand teachers felt challenged by the travelling distance, limited time and also raised the tension of how to scale-up maths professional development initiatives to include schools from their community. The study makes a theoretical contribution by illustrating how Bernstein’s pedagogic identity model and its elaboration by Tyler (1999) provides analytical tools to interrogate macro educational changes and connect these to the micro processes and teacher identities.
- Full Text:
- Date Issued: 2015
Pro-active visualization of cyber security on a National Level : a South African case study
- Authors: Swart, Ignatius Petrus
- Date: 2015
- Subjects: Internet -- Security measures -- South Africa , Computer security -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4718 , http://hdl.handle.net/10962/d1017940
- Description: The need for increased national cyber security situational awareness is evident from the growing number of published national cyber security strategies. Governments are progressively seen as responsible for cyber security, but at the same time increasingly constrained by legal, privacy and resource considerations. Infrastructure and services that form part of the national cyber domain are often not under the control of government, necessitating the need for information sharing between governments and commercial partners. While sharing of security information is necessary, it typically requires considerable time to be implemented effectively. In an effort to decrease the time and effort required for cyber security situational awareness, this study considered commercially available data sources relating to a national cyber domain. Open source information is typically used by attackers to gather information with great success. An understanding of the data provided by these sources can also afford decision makers the opportunity to set priorities more effectively. Through the use of an adapted Joint Directors of Laboratories (JDL) fusion model, an experimental system was implemented that visualized the potential that open source intelligence could have on cyber situational awareness. Datasets used in the validation of the model contained information obtained from eight different data sources over a two year period with a focus on the South African .co.za sub domain. Over a million infrastructure devices were examined in this study along with information pertaining to a potential 88 million vulnerabilities on these devices. During the examination of data sources, a severe lack of information regarding the human aspect in cyber security was identified that led to the creation of a novel Personally Identifiable Information detection sensor (PII). The resultant two million records pertaining to PII in the South African domain were incorporated into the data fusion experiment for processing. The results of this processing are discussed in the three case studies. The results offered in this study aim to highlight how data fusion and effective visualization can serve to move national cyber security from a primarily reactive undertaking to a more pro-active model.
- Full Text:
- Date Issued: 2015
- Authors: Swart, Ignatius Petrus
- Date: 2015
- Subjects: Internet -- Security measures -- South Africa , Computer security -- Government policy -- South Africa
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: vital:4718 , http://hdl.handle.net/10962/d1017940
- Description: The need for increased national cyber security situational awareness is evident from the growing number of published national cyber security strategies. Governments are progressively seen as responsible for cyber security, but at the same time increasingly constrained by legal, privacy and resource considerations. Infrastructure and services that form part of the national cyber domain are often not under the control of government, necessitating the need for information sharing between governments and commercial partners. While sharing of security information is necessary, it typically requires considerable time to be implemented effectively. In an effort to decrease the time and effort required for cyber security situational awareness, this study considered commercially available data sources relating to a national cyber domain. Open source information is typically used by attackers to gather information with great success. An understanding of the data provided by these sources can also afford decision makers the opportunity to set priorities more effectively. Through the use of an adapted Joint Directors of Laboratories (JDL) fusion model, an experimental system was implemented that visualized the potential that open source intelligence could have on cyber situational awareness. Datasets used in the validation of the model contained information obtained from eight different data sources over a two year period with a focus on the South African .co.za sub domain. Over a million infrastructure devices were examined in this study along with information pertaining to a potential 88 million vulnerabilities on these devices. During the examination of data sources, a severe lack of information regarding the human aspect in cyber security was identified that led to the creation of a novel Personally Identifiable Information detection sensor (PII). The resultant two million records pertaining to PII in the South African domain were incorporated into the data fusion experiment for processing. The results of this processing are discussed in the three case studies. The results offered in this study aim to highlight how data fusion and effective visualization can serve to move national cyber security from a primarily reactive undertaking to a more pro-active model.
- Full Text:
- Date Issued: 2015