List of Titles

The National Skills Fund and green skills: towards a generative mechanism approach

Authors: Sauls, Gideon George
Date: 2018
Subjects: South Africa. National Skills Fund , Environmental education Finance South Africa , Green technology Study and teaching South Africa , Postsecondary education South Africa
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/63740 , vital:28482
Description: The aim of the study was to investigate the role of the South African National Skills Fund (NSF) in responding to green skills training for the sake of better integration and optimal effectiveness in relation to the green economy in South Africa. The NSF is a multi-billion rand fund for skills development, with the responsibility to respond effectively to the country’s skills development needs. Part of the NSF’s mandate is to ensure the development of green skills in South Africa, with special reference to the allocation of grants, as a key mechanism in ensuring adherence to properly governed skills development funding requirements. This study considers the identification of green skills funding as a skills planning and implementation challenge within the post-school education and training context, the NSF, the green economy and related skills debates, both locally and globally. The study contributes to a growing body of research in South Africa that seeks a wider systemic perspective on green skills concerns. The NSF and its functioning is a critical dimension of the wider skills system and is a significant system element influencing further emergence of a coherent national system for green skills development. Providing further rationale for this study is the 2011 finding of the International Labour Organisation, that the green skills development system in South Africa is re-active and poorly systematised, a finding that was also noted in the first ever Environmental Sector Skills Plan for South Africa undertaken by the Department of Environmental Affairs in 2010. As the study is mainly focused on one aspect of the policy system, namely the NSF’s role in green skills funding, the bulk of the data used in this study is documentary. Research information was obtained from NSF documentary sources to describe the NSF organisationally. Information was also obtained from green skills documentary sources to obtain a better understanding of the nature and purpose of the development of green skills in South Africa. The study has also drawn on references related to grant management as a mechanism for seeding meaningful transformations and skills development research in South Africa to understand the skills development landscape, with special reference to the Department of Higher Education and Training’s (DHET) post-school education and training system. Documentary data was supplemented by selected key respondent interviews from the skills sector and from the green skills research community to provide further perspective on the research focus. Critical realism (CR) is utilised as a meta-theoretical framework that seeks to inform the overall academic reflection and interpretation process. The work of Danermark, Ekström, Jakobsen and Karlsson (2002), which describes the process of data analysis in critical realism, was adapted into a four-phased research approach for this particular policy study, which I framed as a Quadrilateral Policy Analysis Framework (QPAF). This provided a data analysis framework which allowed for taking account of the mechanisms shaping the NSF as an important systemic funding agency within South Africa’s emerging post-school education and training context, as this relates to green skills. However, to further analyse this research question and context, I needed to work with substantive policy theory. Given the nature of the policy object that I was investigating, I found Feiock’s (2013) Institutional Collective Action Framework to be a helpful substantive policy theory as it has adequate nuance with which I could describe the NSF’s core function, namely that of grant-making for the post-schooling policy context. Based on the critical realist meta-theoretical framework and the substantive policy theoretical frameworks, I developed four phases of analysis, namely a) descriptive analysis which is divided into Part A (describing the green skills landscape and its funding demands ) and Part B (describing the NSF as it relates to green skills); b) component analysis which further analyses key components of the above; c) abductive policy analysis which identifies critical mechanisms and how they operate; and d) generative mechanism analysis which identifies the underlying generative mechanisms shaping the NSF’s engagement with green skills (or lack thereof). The following main findings are identified: • It emerged that the responsiveness of the NSF to green skills is emergent, essential and yet multifaceted due to competing stakeholder interests, expectations and claims; • Key strategic relations with critical role players within South Africa’s skills levy funding matrix emerged as a fundamental requirement towards the achievement of the NSF’s organisational mandate to respond effectively to national green skills needs and expectations; • Contracting is the central mechanism driving the NSF grant-making process. Related to this is the finding that partnerships emerged as the most versatile and underutilised mechanism that cuts across all four of the NSF grant-making phases; • The NSF’s current method of making sense of funding policy indications as per national policy documents is too reductionist because the method betrays an alignment-mirroring form of sense-making awareness that uncritically endorses substratum philosophical assumptions like Human Capital Theory (HCT) and associated neoclassical economic theories embedded in the policy frameworks. These assumptions contradict and potentially limit engagement with wider theories and policy frameworks for guiding skills development that are oriented towards the wider common good as argued by non-anthropocentric orientations in critical realism and the green skills sector. In summary, an argument is put forward that the NSF is a key funding mechanism towards green skills delivery in South Africa, but that this funding mechanism is under-utilised and inadequately mobilised for transitioning towards sustainability in South Africa. The study recommends that, in pursuit of better integration and optimal effectiveness thereof and in line with the fund’s legislative, organisational and public mandate, a consensual negotiation skills planning mechanism be considered from an institutional collective action response platform. In terms of recommendations for further research, it is proposed that a comparative analysis study could be considered between the NSF and other leading global funding agencies or other national skills funding mechanisms that are also concerned with the inclusion of green skills development. Comparative studies of this nature could potentially enhance the fund’s policy-making process and assist in the development of more appropriate institutional arrangements towards optimal funding responsiveness. Lastly, in the light of the NSF’s current contribution to green skills in the country, an impact evaluation study on the return on green skills investment presents an additional intriguing research endeavour which would contribute further perspective on the arguments presented in this study.
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Date Issued: 2018

Studies of the population structure and generic diversity of domesticated and "wild" ostriches (Struthio camelus)

Authors: Bezuidenhout, Cornelius Carlos
Date: 2000
Subjects: Ostriches Ostriches -- Genetics Ostriches -- South Africa
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:3907 , http://hdl.handle.net/10962/d1003966
Description: DNA sequencing and restriction fragment length polymorphism analysis (RFLP) of polymerase chain reaction (PCR) amplified mitochondrial DNA fragments, and random amplified polymorphic DNA sequence (RAPD) analysis were techniques evaluated in this study for applicability in the investigation various aspects of genetic diversity within the ostrich (Struthio camelus). The genetic aspects that were investigated were (i) relationships between ostrich subspecies, (ii) genetic variability between and within domesticated populations of southern African ostriches (Struthio camelus australis), (iii) linking egg production in domesticated ostriches to RAPD profiles, and (iv) determining the zygosity of twin ostriches. In the first part of this study DNA sequencing and the polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) methods were evaluated for resolving genetic differences in the small mtDNA fragments ofthe ostrich. DNA sequencing ofPCR amplified 450 bp 12S rRNA gene fragments of representatives from the southern African population ostrich (S.c. australis) did not reveal any differences between the populatiohs from different geographical areas, representing ostrich lineages with different breeding histories. The PCRRFLP analysis ofmtDNA fragments (450 bp 12S rRNA gene fragment and 550 bp D-loop region) also did not reveal any genetic variability between the domesticated s.,c. australis populations included in this study. PCR-RFLP analysis of a 450 bp 12S rRNA gene fragment, however, showed differences between the subspecies s.c. australis and s.c. molybdophanes. The proportion of shared fragments (F) between these two subspecies was 0.286 and nucleotide sequence divergence estimated at 8.9 %. Divergence time between these two subspecies was estimated at 4.5 million years ago. The data presented from this study are comparable to the data from a previous study in which the entire mitochondrial genome and a larger number of restriction enzymes were used. The PCR-RFLP method thus demonstrated its usefulness for genetic studies of ostriches at thesubspecies level. The sequences used in this study could not reveal any markers that were useful for genetic studies of ostriches at the population level. In the second part of the study the RAPD method was evaluated for application in the genetic studies of ostriches. RAPD profiles, based on three RAPD primers, revealed differences between three subspecies of ostriches and indicated relationships between these subspecies that are consistent with observations from other studies. The numerical analysis of pooled and individual primer data demonstrated that the subspecies s.c. australis is more closely related to s.c. massaicus than to s.c. molybdophanes. RAPD marker differences between s.c. molybdophanes on the one hand, and s.c. massaicus and s.c. australis on the other is also consistent with observations from studies that proposed separate specie~ status for s.c. molybdophanes. RAPD analysis by five primers revealed geographic variation between s.c. australis populations. The clustering patterns observed in the dendrograms and Neighbour Joining Trees generated by computer programs showed trends of separating ostric1;t populations into geographical groups, possibly reflecting their different breeding histories. In the RAPD profiles of the inbred population, band-sharing was generally greater than in the outbreeding group. RAPD analysis thus showed that it may be a useful method in the population studies of domesticated S. c. australis. RAPDs also generated data that grouped ostriches according to trends in egg production capabilities. Analysis ofRAPD profiles by computer software showed a Neighbour Joining Tree and a dendrogram that predominantly grouped ostriches into clusters associated with either good or poor egg production. Evidence supporting the suitability of RAPDs as a tool in breeding programmes of ostriches was thus provided by this study. RAPDs also provided data, demonstrating that two sets of ostrich twins were non-identical twins. It was demonstrated by this study that RAPDs analysis may be a useful technique for applying to (1) systematic (2) population (3) breeding and (4) twin studies of ostriches (Struthio camelus).
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Date Issued: 2000

Bush clumps as indicators of thresholds of change in Arid Thicket mosaic piospheres

Authors: Schmidt, Anton George
Date: 2017
Subjects: Biodiversity conservation Ecological processes
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10948/20811 , vital:29403
Description: In the literature, Arid Thicket transformation by domestic meso-herbivores is purported to follow a state-and-transition model, whereby the ecosystem is initially resilient to herbivory until some threshold is crossed, where after there is a rapid shift to a new alternative stable state. My study represents a first attempt to verify this hypothesis by searching for evidence of stable ecosystem states separated by structural, functional and degradation thresholds in Pruim-Spekboomveld, a variation of Arid Thicket found in the southern Cape of South Africa. In this variation, thicket bush clumps ranging in size from approximately 1 m2 to 100 m2 are interspersed in a matrix of Succulent Karoo vegetation. I correlate structural and functional attributes of the thicket bush clumps and the soil environment beneath them (indicators of ecosystem function) to distance from artificial watering points in four piosphere treatments that have had a different rangeland management history. I mostly fit linear, exponential and sigmoid regression models to my data and use Akaike’s Information Criterion to select the best fitting model. When analysing data on changes in the variation of vegetation production with distance from water using the Normalized Difference Vegetation Index, I additionally fit Generalized Additive Models to the data to take into account more complex predicted patterns of change. Furthermore, I compare the end regions of my data in the piosphere treatments to each other and to similar data collected in a transformed and untransformed reference site. I use both the pattern and extent of transformation within and between the treatments and the reference sites, to verify the existence of stable states and structural, functional and degradation thresholds. I also subject my entire dataset to multivariate analysis using ordination and permutation procedures, in an attempt to corroborate my results from the univariate analysis and to assess the response of bush clump community composition to herbivory. My results indicate that at the scale of a bush clump, a threshold reduction in species richness, functional type diversity, succulent shrub redundancy and cover, palatable shrub cover and bush clump leaf mass below 1.5 m occurs in regions intensively used by domestic meso-herbivores. Furthermore, at the landscape scale there is a threshold reduction in canopy tree cover and bush clump density. In addition to these structural threshold changes, results from a Landscape Function Analysis indicate that soil nutrient cycling, soil water infiltration and soil stability thresholds are crossed at the landscape scale. The soil nutrient cycling threshold is affirmed by soil chemical analyses which indicate that the most rested treatment in the study area has low carbon and nitrogen levels. Furthermore, the keystone species, Portulacaria afra, is unable to re-establish itself in any of the treatments. High pH and potassium levels in all the treatments, relative to the untransformed reference site, indicate that Portulacaria afra (which prefers moderate soil conditions) is unlikely to re-establish in the study area. This finding suggests that all my treatments have crossed a degradation threshold and therefore represent an alternative stable state to the untransformed reference site. My multivariate analysis supports this finding and further indicates that the sampling zones within 25 m of the watering points in the most utilized treatments have crossed a second degradation threshold. This finding is supported by my results that indicate that structural and function thresholds (related to the size, density and ability of bush clumps to capture and retain soil resources) have been crossed. Furthermore, excessively high concentrations of base cations in these sampling zones, relative to the untransformed reference site, affirm the crossing of a degradation threshold. My results on the changes in the variation of vegetation production with distance from water using the Normalized Difference Vegetation Index, support the growing body of evidence in the literature that suggests that increases in the variance of ecosystem processes and services are important indicators of impending ecological thresholds. In general, my findings support the prediction in the literature that domestic meso-herbivore induced transformation of Arid Mosaic Thicket will follow a state-andtransition model.
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Date Issued: 2017

A social realist account of the tutorial system at the University of Johannesburg

Authors: Layton, Delia Melanie
Date: 2013
Subjects: University of Johannesburg Education, Higher -- South Africa Tutors and tutoring -- South Africa College teaching -- South Africa Archer, Margaret Scotford College student development programs -- South Africa Social realism , Tutorial system
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:1314 , http://hdl.handle.net/10962/d1001621
Description: Using Margaret Archer’s social realist methodology, this study critically examines the construction of the tutorial system in several departments and faculties at the Auckland Park campus of the University of Johannesburg. The purpose of the study is to investigate the extent to which tutorials support the acquisition of programme and disciplinary epistemologies. Social realism calls for analytical dualism of ‘the people’ (agents) from ‘the parts’ (structure and culture). This requires the separate consideration of structures (social systems, rules, roles, practices, policies, institutions, and organisational structures like committees, units, departments, faculties), culture (ideologies, theories, beliefs and values as evidenced in discourses), and agency (people and their ability to act within and upon their own world in terms of their social roles and positions dependent on their ability to activate their emergent properties and powers). Through this investigation, an understanding was gained into how the emergent properties and powers contained within the material, ideational and agential elements helped to generate certain events and practices in the tutorial system. These generative mechanisms were examined to explore whether they enabled or constrained the construction of the tutorial system to provide epistemological access. The study shows that while many official policy documents construct the tutorial system as being an intervention to support academic success, particularly for first-years, there are some tensions within the document discourses, where, on the one hand, student success is constructed in terms of throughput numbers, or, on the other hand, as being about becoming a particular kind of person who is able to access and add to powerful knowledge. Furthermore, the study found that policies are not being consistently implemented. While certain key agents and actors, in the form of management, academics and tutors, were found to be able to overcome constraints and introduce innovative ways of enhancing access to target epistemologies, there is a need for consideration of structural and cultural constraints. For example, structures in the form of funding, venues and timetabling were found to constrain the tutorial system as did some of the discourses in the cultural domain: for example, in the form of certain dominant discourses around teaching and learning, beliefs about the purpose of the tutorial and the relationship between academics and the tutorial system. The study also found that the ontological aspects of ‘learning to be’ were not fore-grounded to any great extent in the ways in which the tutorial system was constructed. There needs to be more consideration of the ontological as well as the epistemological aspects of first-year study so as to take cognisance of the different learning needs of an increasingly diverse student body and to encourage the development of the student agency necessary for a deep engagement with the disciplinary epistemologies.
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Date Issued: 2013

A systems approach to mainstreaming environment and sustainability in universities : the case of Rhodes University, South Africa

Authors: Togo, Muchaiteyi
Date: 2009
Subjects: Rhodes University Education, Higher -- South Africa Universities and colleges -- South Africa Universities and colleges -- Environmental aspects -- South Africa -- Case studies Environmental education -- South Africa -- Case studies Sustainable development -- South Africa -- Case studies
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:4768 , http://hdl.handle.net/10962/d1007175
Description: This study is influenced by the objectives of the Mainstreaming Environment and Sustainability in African Universities Partnership which aims to enhance the quality and relevance of university education through implementation of Environmental Education and sustainability across university functions and operations. It contributes to Education for Sustainable Development through the development of tools to assess sustainability in higher education, investigating sustainability practices in universities and proposing strategies for improving mainstreaming of sustainability. It also contributes to systems approaches in mainstreaming contextual sustainability challenges in university functions and operations. The aim of the study was to investigate how universities can mainstream sustainability in their functions and operations in response to contextual sustainability challenges in a changing environment using a systems approach. The research was a case study of Rhodes University in South Africa, which is situated in the impoverished Eastern Cape Province. The study involved 12 teaching departments (representing all faculties at the university), four research units and institutes, five managements units, the Estates Division and the Student Representative Council. The theoretical framework of the study draws from a critical realist ontology and systems thinking epistemology. Systems thinking emphasises the interdependencies of phenomena, thus providing the methodology and tools for a systems view of relationships between education and the environmental context in which it is embedded. Critical realism was employed as an underlabourer to systems thinking as it provides for some of the dimensions absent in systems thinking including its depth ontology which facilitates isolating causal factors influencing empirical reality. It recognises that explanation of phenomena can be embedded in history and acknowledges the fallibility of knowledge. The data collection methods employed in the study include a sustainability assessment using a Unit-based Sustainability Assessment Tool developed as part of the study, interviews, content analyses and observations. Data analyses were performed through employing morphogenetic analysis, and inductive, abductive and retroductive modes of inference. The morphogenetic analysis of social transformation/reproduction was employed to trace the historical emergence of sustainability initiatives at Rhodes University. Induction facilitated reorganisation of the data into themes which particularly represent the main sustainability activities at Rhodes University. Abduction, through recontextualising data in a systems thinking framework, enabled further insights into the phenomena. In the study, it enabled use of systems lenses as a framework and led to identification of systemic issues affecting mainstreaming and later, the development of systems thinking approaches in mainstreaming sustainability. Retroduction enabled identification of causal mechanisms which influenced the emergence of sustainability initiatives at the university. The study established that the emergence of sustainability initiatives at Rhodes University followed the 1990 Talloires Declaration and paralleled international institutional developments in relation to environmental and sustainability challenges. Since then, sustainability initiatives have continuously been emerging in various operational dimensions of the university in line with emerging sustainability challenges which resulted in a morphogenetic cycle. The study revealed that Rhodes University has mainstreamed sustainability across the functions and operations of most of the departments/divisions/units forming part of the study, especially in functions like teaching, research, community engagement and operations. There were a few exceptions like the Human Resources Division and to an extent the Research Office/Management Division which are not yet considering sustainability in their operations. While most of the teaching departments had sustainability initiatives in teaching, research and community engagement, there was diversity in the dimension(s) of sustainable development that the departments addressed and this seemed to relate to the disciplinary content of their subjects. In the Estates Division sustainability initiatives included sustainable landscaping, campus environmental management, water and energy conservation initiatives, waste recycling, use of biodiesel, to mention a few. Students were also involved in various sustainability activities especially through voluntary community engagement initiatives. Sustainability initiatives at the university were also discovered to be embedded within and responding to sustainability challenges of the immediate university environment of Makana District. The study unearthed the causal mechanisms enabling and constraining mainstreaming activities at the university. These were found to be embedded in the history and context within which the university is operating, and other factors related to university structures and agency of lecturers, other employees and students. Examples of these factors are unsustainable patterns in society, policies and the need to redress past inequalities. The study noted the existence of systemic issues at the university which need to be addressed to enable and enhance the promotion of a systems approach to mainstreaming: notably, complexity owing to diversity of approaches employed in mainstreaming, the absence of clearly defined university sustainability goals, problems of institutional support and in some cases, disciplinary governing rules which do not leave room for mainstreaming sustainability. The study established the possibility of improving mainstreaming of sustainability through the adoption of more explicit systems approaches. It suggests use of systems models including the systems-environment model, the functions/structure model and the motion picture model in the process. It recommends making the goal of mainstreaming more upfront, developing a shared understanding of sustainability and mapping out/defining contextual sustainable development issues to grapple with. The study also recommends adopting a holistic approach in mainstreaming, making it a campus-wide initiative, involving all students and developing interdisciplinary curricula. It suggests setting up of supporting mechanisms to strengthen, extend and spearhead mainstreaming and enhancement of collaborative work in sustainable development issues.
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Date Issued: 2009

Assessment of the implementation of the National Certificate (Vocational) plant production modules

Authors: Langa, Phakama Perry Macmillan
Date: 2016
Subjects: Curriculum planning Technical education -- Curricula Vocational education -- Curricula
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10353/2359 , vital:27778
Description: From 2010, the South African vocational skills education is offered by the Department of Higher Education and Training (DHET) through the Technical Vocational Education and Training (TVET) colleges. TVET colleges need to be transformed in order to empower young learners with the skills required by the various sectors of the economy. The purpose of this study was to assess the implementation of the National Certificate (Vocational) Plant Production module in Training and Vocational Education and Training (TVET) Colleges. The sample for this study is concurrent triangulation whereby complementary methods of data sources were brought together to offset each other‘s weaknesses. The sample for this study consisted of participants from three TVET colleges: one deep rural, one semi-rural/semi-urban and one urban in terms of geographical location. A total of 18 participants were interviewed: 2 subject advisors engaged by the colleges, 1 lecturer from college A, 3 lecturers from college B, 2 lecturers from college C, 4 graduates from college B, 3 graduates from college C and 3 employers .Research design for this study has features of both a survey and a case study. The mixed-method approach was applied using document analysis, questionnaires and interviews for data collection. The researcher found out that there is a disparity between the Plant Production guidelines and their implementation and assessment. Among the main reasons for failure to implement the guidelines properly are poor or inadequate infrastructure for doing practical work, high rate of student absenteeism within the investigated categories, and the high drop-out rate at Levels 2–4. To minimize the challenges in offering the Plant Production module, the study recommends that since some colleges cannot afford purchasing large sizes of land to properly implement the Plant Production guidelines, the government and the DHET should link the Primary Agriculture training to the land reform program where students can be trained under the land reform program.
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Date Issued: 2016

Plastochron index - an indicator of plant structure and function a case study using Pisum sativum L

Authors: Ade-Ademilua, Omobolanle Elizabeth
Date: 2006
Subjects: Plant anatomy Plant physiology Peas -- Anatomy Peas -- Physiology
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:4183 , http://hdl.handle.net/10962/d1003751
Description: The use of chronological age for example, using days after sowing (DAS), or days after germination (DAG) as a time variable may result in the inherent variability between plants resulting in differences which can be large enough to obscure subtle developmental trends that become evident among plants sown at the same time. An alternative to DAS or DAG is the plastochron index (PI), first used by Erickson and Michelini (1957) as a morphological time scale and numerical index; which to according to the authors suggested and represented a more accurate reflection of the developmental status of a plant. The research presented in this thesis was therefore aimed specifically at utilizing the index in qualitative and quantitative analyses, to confirm its usefulness in analyzing and predicting plant growth and development. Specifically this research focused on investigating various morphological and physiological events that together, hopefully, would serve as a template for the prediction of the growth, development and reactions of Pisum sativum L. to different growth conditions. In Chapter 3, the use of the average length of the first pair of leaflets on each node as a suitable parameter for calculating PI in P. sativum is suggested. The results presented in Chapter 3 suggest that plant age is best expressed using the plastochron index, as this reflects the time interval between the initiations of successive pairs of leaflets. This section of the research has been published as “Ade-Ademilua OE, Botha CEJ (2005) A re-evaluation of plastochron index in peas - a case for using leaflet length. South African Journal of Botany 71: 76-80”. The PI formula developed was subsequently used in this research to conduct qualitative and quantitative investigations of plant growth and development in which all data and observations were related directly to the plastochron index. In Chapter 4, the sink to source transition in Pisum sativum L. leaves at different plastochron ages in nodulating plants was investigated using the phloem-mobile fluorescent marker, 5,6-carboxyfluorescein (5,6-CF). The results demonstrated that young leaves remained strong sinks up until LPI 0, after which sink-source transition occurred up to LPI 1.8 and leaflets transitioned to strong source systems by LPI 2.0. A well-developed cross-connected phloem system between paired leaflets in peas, and the petiole and the stem vascular supply was observed. The data presented in the second part of Chapter 4 suggest that the phloem transport between leaflet pairs is independent of the sink/source state of the leaflets, or of movement along the source to sink gradient. The data support the presence of a modular transport system which may ensure re-allocation and balancing between leaflets of the same physiological age and photosynthetic and transport status, thereby load-balancing the local transport system, before exporting to other younger (sink) regions. The investigation of leaf development using the plastochron index (Chapter 5) revealed that the formation of air spaces in the palisade and spongy mesophyll, one of the preparatory events for transition from sink to source state in developing leaves, occurs between LPI 0 and LPI 1 in pea leaflets. Results of the anatomical and ultrastructural study related to PI are presented in Chapter 5. The density of wall ingrowths in transfer cells of minor veins increased with LPI and appeared to be associated with the probable transition to source state and the related potential increase in the production of assimilates for export. The onset of wall ingrowth development in leaflets at LPI 0 provided evidence that sink-to-source transition commences at LPI 0 in P. sativum. Presumably-functional plasmodesmata as well as a few mature sieve elements were evident in class IV veins in the apical region of young and older leaflets at LPI 0. The number of mature sieve elements per vein however, increased with increasing LPI. Most class V veins were still undergoing division at LPI 0 and their sieve elements did not show signs of maturity until LPI 1. The increase in the number of mature metaphloem sieve elements in young, supposedly importing tissue at LPI 0 to older, supposedly exporting tissues at LPI 2 is evidence of the association between phloem maturation and transition from importing to exporting status. In Chapter 6, I report on the effects of elevated CO[subscript 2] on the growth and leaf development of nodulating and non-nodulating Pisum sativum L var. Greenfeast grown under controlled environment of the same nitrogen (6mM) and nitrogen- free nutrient solution conditions. Shortterm exposure to elevated CO[subscript 2] induced rapid plant growth, irrespective of treatment. However, long-term elevated CO[subscript 2] treatment did not affect rate of leaf appearance (RLA) in nodulated plants, irrespective of mineral N supply but enhanced RLA in non- nodulating plants supplied with mineral N. Supplied N resulted in a significant increase in leaflet elongation rate (LfER) under both ambient and elevated CO[subscript 2], but LfER was not significantly affected by nodulation but was increased by high CO[subscript 2]. This suggested that the growth of nodulating P. sativum L may not be significantly affected under CO[subscript 2] levels as high as 1000 μmol mol[superscript -1]. The data suggest that elevated CO[subscript 2] will enhance canopy size, provided adequate soil N is available and more so in non-nodulating plants. This section of the research has been published as “Ade-Ademilua OE, Botha CEJ (2004) The effects of elevated CO[subscript 2] and nitrogen availability supersedes the need for nodulation in peas grown under controlled environmental conditions. South African Journal of Botany 70: 816 – 823”. This thesis demonstrates that the similarity in the qualitative analyses results obtained from plants from different CO[subscript 2], nitrogen and nodulation treatment conditions, highlights the fact that plants of same PI value are at the same developmental state, irrespective of the growth condition. Furthermore, changes in plant structure and function observed under different growth conditions can be related simply to changes in plastochron index. The work presented in this thesis demonstrate that changes in plant structure and function analyzed are related to changes in PI. An important finding of this thesis is that with the use of PI, results can be compiled as a template for predicting the structure- function state of pea plants at any plastochron age, under any growth conditions, before using small representative sample populations.
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Date Issued: 2006

Challenging desire : performing whiteness in post-apartheid South Africa

Authors: Smit, Sonja
Date: 2014
Subjects: Performance art -- South Africa , Bailey, Brett, 1967- , Cohen, Steven, 1962- , Antwoord (Musical group) , MacGarry, Michael , Eurocentrism -- South Africa
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:2164 , http://hdl.handle.net/10962/d1016358
Description: The central argument of this thesis asserts that in the process of challenging dominant subject positions, such as whiteness, performance creates the possibilities for new or alternative arrangements of desire. It examines how the creative process of desire is forestalled (reified) by habitual representations of whiteness as a privileged position, and proposes that performance can be a valid form of resistance to static conceptions of race and subjectivity. The discussion takes into account how the privilege of whiteness finds representation through forms of neo-liberalism and neo-colonialism in the post apartheid context. The analysis focuses on the work of white South African artists whose work offers a critique from within the privileged “centre” of whiteness. The research is situated within the inter-disciplinary field of performance studies entailing a reading and application of critical texts to the analysis. Alongside this qualitative methodology surfaces a subjective dialogue with the information presented on whiteness. Part Two includes an analysis of Steven Cohen’s The Cradle of Humankind (2011), Brett Bailey’s Exhibit A (2011) and Michael MacGarry’s LHR-JNB (2010). Each section examines the way in which the respective works engage in a questioning of whiteness through performance. Part Three investigates South African rap-rave duo, Die Antwoord and how their appropriation of Zef interrogates desires for an essential authenticity. Part Four focuses on my own performance practice and the proposed value of engaging with a form of practice-led research. This is particularly relevant in relation to critical race studies that require a level of self-reflexivity from the researcher. It presents an analysis of the work entitled Villain (2012) as a disturbance of theatrical desire through a process of ‘becoming’. This notion of meaning and identity as ‘becoming’ is argued as a strategy to challenge prevailing modes of perception which can possibly restore the production of desire to the viewer. The thesis concludes with the notion that performance can offer a mode of immanent ethics which is significant in creating both vulnerable and critical forms of whiteness.
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Date Issued: 2014

Towards a norm of compliance in recreational fisheries

Authors: Bova, Christopher S
Date: 2019
Subjects: Fishing -- Management -- South Africa , Fishery law and legislation -- South Africa
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/95909 , vital:31213
Description: The activity of fishing can be traced back to prehistoric times. However, only in the last century has there been a focus on the management of fisheries. Fishery regulations are tools used by resource managers with the aim of protecting the long-term sustainability of fishery resources. Although there is an overwhelming amount of evidence demonstrating the decline of fisheries, non-compliance with these regulations by fishers continues to manifest, which can exacerbate the negative ecological impacts of fisheries. Popular methods towards the measurement of noncompliance in fisheries derived from previous human dimensions literature may be flawed. Theories on improving compliance behaviour have typically relied on theory, which has at times proved paradoxical. Addressing the issues of non-compliance within a fishery of interest requires measuring the levels of non-compliance within the fishery and determining the relevant sociopsychological drivers behind the non-compliant behaviour. The data collection methods used during these assessments are limited in human dimensions research and are often case and context specific, requiring researchers to identify which approach is most practical for the specific fishery of interest. By identifying relevant behavioural drivers of non-compliance, a more effective approach aimed at improving compliance can be tailored. The recreational marine-based shore fishery (MBSF) in South Africa is not impervious to noncomplaint behaviour. In fact, it has been estimated to have relatively high rates of non-compliance. This high level of non-compliance makes the South African MBSF a unique and optimal context in which to undertake research that aims to formulate a framework towards compliance assessments and that develops a suitable approach for improving compliance rates. Using surveys to obtain compliance data can provide a range of details about violators, however they are susceptible to social desirability bias (SDB). Choosing the best method for controlling SDB required an assessment of existing methods for doing so. In this first part of the study, only fishers who were covertly observed breaking the rules were surveyed, using one of three methods for reducing SDB, to ground-truth the responses. Ground-truthing was done to determine which method would be most effective for a large-scale study within the same fishery. Of the methods used, which include the direct questioning method (DQM), the random response technique (RRT) and the ballot box method (BBM), all contained some level of SDB. However, the BBM provided a significantly higher level of response accuracy (79.6% ± 11.9) than the DQM (46.5% ± 14.9) and the RRT (44.3% ± 12.5). Random-stratified roving creel compliance surveys that employed the BBM were then undertaken at various locations along South Africa’s coastline to estimate current rates of non-compliance, and the face-to-face results were compared to results from an identical online survey to determine the suitability of online surveys as a replacement. The results indicated that online surveys only represent a subgroup of the fisher population within the MBSF, suggesting that face-to-face survey methods are required to obtain a more comprehensive sample and a more robust estimate of noncompliance. The results, based on 453 face-to-face surveys, showed a high level of overall self-reported noncompliance (48.3%) within the fishery. Responses to Likert scale survey questions on various aspects of the fishery, including angler motivations for fishing, were then modelled to test the relationship between the anglers’ responses and their compliance behaviour. In the South African MBSF context, the most significant behavioural drivers behind non-compliance related to normative concepts. Specifically, the poor perceptions of management and value-based legitimacy as well as low levels of moral obligation to adhere to the regulations appeared to contribute most to the observed non-compliant behaviour. Angler motivations for fishing also played a significant role in determining the compliance behaviour of anglers, with those fishing for food being more likely to violate regulations. In most countries, regardless of economic context, interventions to improve recreational fishery compliance have been developed around the instrumental concept. However, these findings suggest that for recreational fisheries, managers would do well to evaluate the impact of normative concepts on compliance and to design interventions aimed at addressing these. In the case of the South African MBSF, interventions that address angler perceptions of legitimacy and aim to correct misperceptions about social norms of compliance may provide a more practical and cost- effective method for improving poor compliance behaviour.
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Date Issued: 2019

Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films

Authors: Nwaji, Njemuwa Njoku
Date: 2019
Subjects: Electrochemistry , Phthalocyanines , Nanoparticles , Bioconjugates , Thin films , Polymers , Nonlinear optics , Nonlinear optical spectroscopy , Nanostructured materials , Raman effect
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/71625 , vital:29926
Description: A number of zinc, gallium and indium metallophthalocyanines (MPcs) with diverse substituents have been synthesized and characterized using various characterization tools such as proton nuclear magnetic resonance (1HNMR), matrix assisted laser desorption time of flight (MALDI-TOF) mass spectrometry, Fourier-transformed infra-red (FT-IR), Ultraviolet-visible (Uv-vis) spectrophotometry, magnetic circular dichroism and CHNS elemental analysis. The time dependent density functional theory was employed to probe the origin of spectroscopic information in these complexes. Complexes with gallium and indium as central metal showed higher triplet quantum yield compared to the zinc derivatives. Some of the MPcs were covalently linked to nanomaterials such as CdTe, CdTeSe, CdTeSe/ZnO, graphene quantum dots (GQDs) as well as metallic gold (AuNPs) and silver (AgNPs) nanoparticles. Others were either surface assembled onto AuNPs and AgNPs or embedded into polystyrene as polymer source. The phthalocyanine-nanomaterial composites (Pc-NMCs) were characterized with FT-IR, UV-visible spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and X-ray diffractometry (XRD). The thickness of the thin films was determined by utilization of the knife edge attachment of the A Bruker D8 Discover X-ray diffraction. The optical limiting properties (using the open-aperture Z-scan technique) of the MPcs and the Pc-NMCs were investigated. The investigated MPcs complexes generally showed good optical limiting properties. The nonlinear optical response of the MPcs were improved in the presence of nanomaterials such as the semiconductor quantum dots (SQDs), graphene quantum dots (GQDs) as well as metallic AuNPs and AgNPs with MPc-QDs showing the best optical limiting behavior. The optical limiting properties of the MPcs were greatly enhanced in the presence of polymer thin films.
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Date Issued: 2019

The assembly of p-aryl triazole foldamers into double and other super- helical structures

Authors: Okerio, Jaspher Mosomi , Klumperman, Bert
Date: 2017
Subjects: Supramolecular chemistry Chemistry
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10948/20548 , vital:29319
Description: The assembly of poly(para-aryltriazoles) (pPATs), synthesized via Cu(I)-catalysed azide-alkyne cycloaddition, into highly ordered structures is investigated. Firstly, the assembly of the pPATs into double helical structures, as a function of solvent quality and side chain chirality, was studied. The solvents employed (DMF and water) induced changes in van der Waals forces and surface free energy thus influencing the order of the pPATs’ random coils into double helical structures. The observed double helical structures, assembly that was analyzed using ultraviolet-visible (UV-Vis) specroscopy, circular dichroism (CD) spectroscopy, scanning transmission electron microscopy (STEM) and confocal fluorescence imaging microscopy upon addition of 0 – 80% water into the pPATs’ random coils, exhibit stable morphologies stabilized by π-π stacking and hydrogen bonding at 80% water content. The pPATs exist as random coils at 10% water in DMF. At 40% water in DMF, the pPATs’ strands were observed to exist in a side-by-side orientation. The adjacent strands, side by side, intertwine into double helices and eventually stack as the amount of water is increased to 80%. The obtained results present a facile strategy for the fabrication of polymeric double helical structures with stable morphologies. The average diameter of the resulting one-handed and opposite handed double helical structures is about 200 nm, a pitch of 170 nm and an overall length of several micrometres. The assembly of the pPATs into ordered structures in the presence of a neutral organic template and anions was also assessed. Hydrophobic poly(γ-benzyl-L-glutamate) (PBLG) template was introduced at various concentrations and transition region of the pPATs (10% water in DMF). At this stage the PBLG template is CD inactive. The template modified the assembly mechanism to afford structures, which cannot be achieved in its absence. It disallows the organization of the pPATs into double helical structures. The pPATs strands thread around the template and stack into long tubules of up to 10 microns and irregular diameter. The irregular diameter is attributed to uneven threading of pPATs strands around the template at some sections. The sensitivity and binding ability of the pPAT system to halide ions such as F-, Cl- and Br- , which involves re-organization of the aryl-triazole bonds, is explored using NMR and UV-Vis and CD spectroscopies. Br- which induces the highest shift of the triazole C-H proton signal in the NMR analysis also shows the highest dynamic quenching of the pPATs’ UV-Vis and CD spectra. The UV-Vis and CD signals are linearly dependent on the concentration of the anions. This confirms non-aggregation assembly in the presence of anions. Conclusively, the pPATs interact with the bromide anion in aqueous solution, which consequently prevents the aggregation of the foldamers. Finally, using PATs with different amounts of chiral side chains, co-operativity among side chains that leads to transfer, propagation and amplification of chirality is confirmed. A non-linear dependence of the CD signal on the amount of chiral side chains was observed. Chiral amplification was observed as low as 1% of the chiral side chains. However, approximately 20% of the chiral side chains are needed to obtain half the intensity of the cotton effect exhibited by the homochiral pPAT.
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Date Issued: 2017

Ammophila arenaria (L.) Link (marram grass) in South Africa and its potential invasiveness

Authors: Hertling, Ursula Margret
Date: 1998
Subjects: Grasses -- South Africa Alien plants -- South Africa Sand dune plants -- South Africa Grasses -- Ecology -- South Africa Sand dune ecology -- South Africa
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:4198 , http://hdl.handle.net/10962/d1003767
Description: Ammophila arenaria (L.) Link is a European sand binding plant which was introduced to South Africa in the 1870's for the purpose of dune stabilisation. Because of its known invasiveness along the west coast of North America, and the problems South African ecosystems experience with alien invader plants, it was deemed necessary to study the biology and ecology of this species in South Africa. The aim of this thesis is to establish the potential invasiveness of A. arenaria on Cape coastal dunes and assess whether its use for dune stabilisation is still justifiable. A. arenaria occurs nowadays between the Langebaan area on the west coast and Gonubie in the Eastern Cape. Although widespread, the grass appears to occur only in areas where it has been planted. Its unaided spread may be prevented by adverse climatic conditions. Studies on the community biology of South African A. arenaria communities as compared to indigenous dune plant communities and natural A. arenaria communities in Europe cannot confirm the aggressive behaviour that A. arenaria shows in California and Oregon. In South Africa, A. arenaria does not exert strong floristic control over other species or outcompete and replace them, neither does it alter the topography of South African beaches and dunes. It forms weaker species associations and tends to develop communities of little species variability along the coast, thereby proving its alienness in South Africa, but this does not imply its invasiveness. Studies on succession of A. arenaria stabilisation areas show that monospecific A. arenaria plantings can be succeeded by a species-rich indigenous dune scrub or dune fynbos within a few decades. Plant-parasitic nematodes have been recorded, which may play an important role in the succession of A. arenaria stands in South Africa as was observed in Europe. Monitoring of A. arenaria communities and indigenous communities over nearly three years shows that A. arenaria is not spreading and replacing indigenous plants but in fact rather being replaced by the latter. A. arenaria profits from a superior sand burial tolerance but is affected by adverse climatic factors, mostly the lack of rainfall and strong radiation. In comparison to the indigenous dune grasses Thinopyrum distichum and Ehrharta villosa, it does not show any superior demographic traits such as an unusually high growth rate or large aboveground biomass production. Although A. arenaria produces viable seed in South Africa, the indigenous grasses show better germination and seedling establishment in the field. This study indicates that A. arenaria is not invasive in South Africa, nor likely to become an invader species in the near future. However, more research is required to confirm these results and more caution recommended regarding the further use of this alien grass for dune stabilisation.
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Date Issued: 1998

Culturally-informed coping strategies of posttraumatic stress disorders among the black Africans in the greater Accra region of Ghana and black Africans in the eastern cape of South Africa

Authors: Thompson, Sandra
Date: 2019
Subjects: Posttraumatic stress disorder
Language: English
Type: Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10948/44625 , vital:38154
Description: The influence of culture in coping with Posttraumatic Stress Disorders (PTSD) has been highlighted in literature. However, these culture specific coping strategies are not as yet, extensively explored. The research sought to explore and describe the culturally - informed coping strategies of PTS D among the black Africans in the Greater Accra Region of Ghana and black Africans in the Eastern Cape of South Africa. A qualitative methodological approach was used to explore the phenomenon under study. Purposive non - probability sampling was employed to obtain access to participants who could inform the objectives of the study. Data was collected using semi - structured interviews with traumatised individuals and focus group discussions with cultural leaders. All interviews were audio - recorded, transcribed, translated and analysed using thematic content analysis to facilitate the description and comparison of the similarities and distinctive features emerging from the two African communities. The findings indicated that a number of cultural factors influence interpretation of symptoms of PTSD and the adopted coping strategies. Participants’ understanding of symptoms of PTSD relied heavily on Christian Religious and African cultural understandings. It was evident that almost all explanations were purely spiritual and minimal knowledge was expressed on cognitive interpretations. A great deal of emphasis by the Ghanaians and isiXhosa of South Africa, was on dreams and such interpretations were deferred to an authoritative individual (especially the traditional healer). An obvious hierarchy for coping emerged with the traditional healer playing a major role for the Ghanaian and isiXhosa participants. Performing rites and the use of plants were essential to healing for these group of individuals. Whereas, the Coloured - Afrikaans made reference to a higher power “God”. An outstanding observation was the extent to which Ghanaian and isiXhosa participants have incorporated Christian and traditional practices (i.e. praying to God, performing rites and using herbs or plants). Even where an individual did not wish to mix practice because of upbringing, they acknowledged the existence and effectiveness of these practices. Colonisation was drawn on as an explanation for such mixed practices. The advent of Christianity was explained as having established Western culture (specifically Christianity) that is incorporated by participants. The Coloured - Afrikaans on the other hand, were consistent with the Christian practices “prayers to God”. A great deal of consistency however existed among all participants. Social support was considered very important. Talking with family and friends were relevant to the healing process as it gets rid of distorted thought patterns and avoids isolation considered as a serious current threat to healing. While there was an element of cognitive understanding, Western based treatment using cognitive restructuring was not a treatment option. Clinical practitioners or Psychologists that come into contact with the black Ghanaians and black South Africans should consider collaborative treatment strategies using the draft checklist as a guide.
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Date Issued: 2019

The investigation, development and characterisation of novel zirconium-based tanning agents

Authors: Guthrie-Strachan, Jeffry James
Date: 2006
Subjects: Zirconium Tanning Leather
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:4319 , http://hdl.handle.net/10962/d1004977
Description: Various oxygen- and nitrogen-donor ligands were investigated as potential zirconium masking agents in zirconium tanning. α-Hydroxycarboxylic acid ligands were identified as effective zirconium(IV) chelators in acidic aqueous solution. Glycolic acid, lactic acid, mandelic acid, 4-hydroxymandelic acid, 4-chloromandelic acid and 4-bromomandelic acid complexes were synthesised, isolated and characterised using a range of analytical techniques. Linear Free Energy Relationships were examined to optimise the stability of the zirconium complexes. Hammett [sigma] plots and Yukawa-Tsuno modified σ plots of the mandelate ligand and zirconium complex series indicated that inductive effects dominate within the benzene ring, however, mesomeric effects are significant outside the ring. Zirconium 4-hydroxymandelate complex solutions were identified as the most effective tanning agents and achieved shrinkage temperatures of 80 and 97ºC for hide powder and goatskin, respectively. The zirconium and 4-hydroxymandelic acid interact synergistically to yield leather equivalent to combination tanned leather in one step. Tanning was performed similarly to vegetable tanning processes with a pickle pH of approximately 5 and fixation was achieved upon acidification. Pilot-scale tanning of goatskin produced white tanned leathers and crust leathers which were physically and aesthetically comparable to matched chromium tanned material.
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Date Issued: 2006

Characterisation of Trypanosomal Type III and Type IV Hsp40 proteins

Authors: Louw, Cassandra Alexandrovna
Date: 2009
Subjects: Trypanosoma Heat shock proteins African trypanosomiasis Epidemic encephalitis
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:3926 , http://hdl.handle.net/10962/d1003985
Description: The heat shock protein-70 (Hsp70) family of molecular chaperones are ubiquitous highly conserved proteins that are critical for the viability of cellular homeostasis. The ATPase activity of Hsp70 proteins is critical to their function as the affinity of a given Hsp70 for non-native substrate is modulated by ATP binding and hydrolysis. When bound to ATP, Hsp70s possess a low affinity for a given substrate protein, while the hydrolysis of ATP to ADP causes a conformational change that results in a high affinity for substrate proteins. The basal ATPase activity of Hsp70s is too low to facilitate their function in vivo, and co-chaperones are essential to modulate the efficient protein folding by Hsp70. Heat shock protein-40 (Hsp40) heat shock proteins are essential for the in vivo function of Hsp70s by stimulating the ATPase activity of these proteins and facilitating transfer of substrates. The Type III class of Hsp40 proteins have not been well characterised due to their poor levels of conservation at the primary sequence level. This is due to the fact that Type III Hsp40s only contain a J-domain and a poorly conserved C-terminal region. The newly identified Type IV class of Hsp40s, contain an abrogated HPD tripeptide motif in the J-domain and have also not been extensively studied. Trypanosoma brucei (T. brucei) is a unicellular flagellated protozoan parasite. It is the causative agent of Human African Trypansomiasis (HAT) which results in thousands of deaths and devastating agricultural losses in many parts of Africa. T. brucei undergoes a complex lifecycle that is characterised by the transition from an insect vector to a mammalian host in markedly different conditions of temperature, pH, nutrient availability and respiratory requirements. It has been proposed that molecular chaperones may enhance the survival of these parasites due to their cytoprotective effect in combating cellular stress. Due to the fact that T. brucei infection is invariably fatal if left untreated, and that no novel treatment regimens have been developed recently, the identification of potential novel drug targets among proteins essential to the parasite’s survival in the host organism is an attractive aspect of T. brucei research. Because Type III Hsp40s are poorly conserved with respect to Hsp40s found in the human host, the identification of any of these proteins found to be essential to T. brucei survival in humans could potentially make attractive novel drug targets. An in depth in silico investigation into the Type III Hsp40 complement as well as partner Hsp70 proteins in T.brucei was performed. T. brucei possesses 65 Hsp40 proteins, of which 47 were classed as Type III and 6 of which were identified as being putative Type IV Hsp40s. A small but significant number (5) of Type III TbHsp40s contained tetratricopeptide (TPR) domains in addition to the J-domain. The J-domains of the Type III TbHsp40 complement were found to be conserved with respect to those of canonical Hsp40 proteins, although the mutation of certain residues that play a key role in Hsp40-Hsp70 interaction was noted. Potential partnerships of these proteins in the parasite was also investigated. The coding regions of three previously uncharacterised TbHsp40s were successfully amplified from T. brucei TREU927 genomic DNA and cloned into an expression vector. Tbj1, a Tcj1 ortholog, was selected for further study and successfully expressed and biochemically characterised. Tbj1 expressed in E. coli was found to be insoluble, but large amounts were recovered with the aid of a denaturing purification followed by refolding elution strategies, and the bulk of the protein recovered was in compact monomeric form as determined by size-exclusion chromatography fast protein liquid chromatography (SEC-FPLC). The addition of Tbj1 to a thermally aggregated substrate resulted in increased levels of aggregation, although Tbj1 was able to assist two Hsp70 proteins in the suppression of aggregation. Tbj1 proved unable to stimulate the ATPase activity of these same Hsp70s, and could not rescue temperature sensitive cells when replacing E.coli DnaJ and CbpA. It was concluded that Tbj1 does not possess independent chaperone activity, but could display Hsp40 co-chaperone properties under certain circumstances. This could allude to a specialised function in the T. brucei parasite. The lack of human orthologues to Tbj1 could result in the attractiveness of this protein as a novel drug target.
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Date Issued: 2009

Application of computational methods in elucidating the isomerization step in the biosynthesis of coumarins

Authors: Tshiwawa, Tendamudzimu
Date: 2019
Subjects: Coumarins , Isomerization , Biosynthesis , Organic compounds -- Synthesis , Cinnamic acid
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/67646 , vital:29124
Description: The identity of the enzyme(s) responsible for the biosynthetic transformation of cinnamic acid derivatives to important, naturally occurring coumarins has yet to be established. This study constitutes a high-level theoretical analysis of the possibility that a recently reported molecular mechanism of the synthesis of coumarins from Baylis-Hillman adducts, may provide a viable model for three critical phases in the biosynthetic pathway Particular attention has been given to the first of these phases: i) E→Z isomerisation of the cinnamic acid precursor; ii) Cyclisation (lactonisation) to the hemi-acetal intermediate; and ii) Dehydration to afford the coumarin derivative. In order to accomplish this analysis, an enzyme capable, theoretically, of effecting this E→Z isomerisation required identification, and its potential involvement in the transformation mechanism explored. Combined Molecular Mechanics and high-level Quantum Mechanical/DFT calculations were used to access complementary models of appropriate complexes and relevant processes within the enzyme active sites of a range of eleven Chalcone Isomerase (CHI) enzyme candidates, the structures of which were downloaded from the Protein Data Bank. Detailed B3LYP/6-31+G(d,p) calculations have provided pictures of the relative populations of conformations within the ensemble of conformations available at normal temperatures. Conformations of several protonation states of cinnamic acid derivatives have been studied in this way, and the results obtained showed that coupled protonation and deprotonation of (E)-o-coumaric acid provides a viable approach to achieve the E→Z isomerization. In silico docking of the B3LYP/6-31+G(d,p) optimized (E)-o-coumaric acid derivatives in the active sites of each of the candidate CHI enzymes (CHI) revealed that (E)-o-coumaric acid fits well within the active sites of Medicago Sativa CHI crystallographic structures with 1FM8 showing best potential for not only accommodating (E)-o-coumaric acid , but also providing appropriate protein active site residues to effect the simultaneous protonation and deprotonation of the substrate , two residues being optimally placed to facilitate these critical processes. Further exploration of the chemical properties and qualities of selected CHI enzymes, undertaken using High Throughput Virtual Screening (HTVS), confirmed 1FM8 as a viable choice for further studies of the enzyme-catalysed E→Z isomerization of (E)-o-coumaric acid. A molecular dynamics study, performed to further evaluate the evolution of (E)-o-coumaric acid in the CHI active site over time, showed that the ligand in the 1FM8 active site is not only stable, but also that the desired protein-ligand interactions persist throughout the simulation period to facilitate the E→Z isomerization. An integrated molecular orbital and molecular mechanics (ONIOM) study of the 1FM8-(E)-o-coumaric acid complex, involving the direct protonation and deprotonation of the ligand by protein residues; has provided a plausible mechanism for the E → Z isomerization of (E)-o-coumaric acid within the 1FM8 active site; a transition state complex (with an activation energy of ca. 50 kCal.mol-1) has been located and its connection with both the (E)- and (Z)-o-coumaric acid isomer has been confirmed by Intrinsic Reaction Coordinate (IRC) calculations. More realistic models of the 1FM8-(E)-o-coumaric acid complex, with the inclusion of water solvent molecules, have been obtained at both the QM/MM and adaptive QM/MM levels which simulate the dynamic active site at the QM level. The results indicate that the simultaneous protonation and deprotonation of (E)-o-coumaric acid within the CHI enzyme is a water-mediated process – a conclusion consistent with similar reported processes. Visual inspection of the 1FM8-(Z)-o-coumaric acid complex reveals both the necessary orientation of the phenolic and carboxylic acid moieties of the (Z)-o-coumaric acid and the presence of appropriate, proximal active site residues with the potential to permit catalysis of the subsequent lactonisation and dehydration steps required to generate coumarin.
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Date Issued: 2019

The role of conflict management in maintenance of discipline : the case of Kenya's public secondary schools

Authors: Kibui, Agnes Wanja
Date: 2013
Subjects: School discipline -- Kenya , Discipline of children -- Kenya
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:16151 , http://hdl.handle.net/10948/d1020074
Description: This study set out to establish the role of conflict Management in Maintenance of Discipline in Kenya’s Public Secondary Schools. The study formulated 6 objectives as follows: examine the nature of Conflict experienced in Public Secondary Schools in Kenya; establish how teachers and students perceive conflict in secondary schools; determine how teachers and students experience conflict in Secondary Schools; investigate the effectiveness of conflict Management Programmes used in Secondary Schools; discover suitable conflict management programmes to address present and future conflict in secondary schools; generate findings based on a theoretical approach for understanding and managing conflict in secondary schools with particular reference to schools in Kenya. The research was conducted in the form of a descriptive survey design with a mixed methods approach which combined qualitative research design and quantitative research technique. A sample of 649 Students, 16 secondary school head teachers, and 16 secondary school guidance and counseling officers from 4 provinces in Kenya was used to obtain data for the study. Random and purposive sampling techniques were used. Data was collected using questionnaires and structured interviews. Descriptive statistics such as mean, percentages, standard deviation, and frequencies was used to discuss the research findings. The study also used inferential statistics, particularly chi-square to test the significant statistical differences on the nature of conflict in schools, how students and teachers experience and perceive conflict in different categories of schools. From the findings, students witness conflict in form of theft, 51.7%, bullying, 29 percent, rumours and fights. Results from males and females indicate that drugs are abused in secondary schools (males (26.8%) and females (13.6 percent). All the respondents revealed that students take drugs to please their peers, and to release stress, and for adventure. On the effectiveness of conflict management programmes, a majority of students accept punishment when they break the school rules (80.0%) as they feel that punishments improve their behaviour. Most of the teachers had not had proper training in conflict management and some of them do not understand the role of peer mediation as they lack such programmes in their schools. The study concluded that failure to train teachers in conflict management skills, and to involve students in decision making causes conflict in schools. The study recommended that life skills, and peace keeping lessons should be taught in schools. In addition, head teachers and teachers should go for a refresher course in conflict management. Also, the study recommends that a comparative study should be done in a wider scope in secondary schools that experience conflict and those that do not, so as to get an insight of the suitable strategies needed to manage conflict in schools.
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Date Issued: 2013

Production of Cydia pomonella granulovirus (CpGV) in a heteralogous host, Thaumatotibia Leucotreta (Meyrick) (False codling moth)

Authors: Chambers, Craig Brian
Date: 2015
Subjects: Cryptophlebia leucotreta -- South Africa , Codling moth -- South Africa , Apples -- Diseases and pests -- South Africa , Codling moth -- Biological control -- South Africa , Insect pests -- Biological control -- South Africa , Biological pest control agents -- South Africa , Baculoviruses -- South Africa
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:5935 , http://hdl.handle.net/10962/d1017906
Description: Cydia pomonella (Linnaeus) (Family: Tortricidae), the codling moth, is considered one of the most significant pests of apples and pears worldwide, causing up to 80% crop loss in orchards if no control measures are applied. Cydia pomonella is oligophagous feeding on a number of alternate hosts including quince, walnuts, apricots, peaches, plums and nectarines. Historically the control of this pest has been achieved with the use of various chemical control strategies which have maintained pest levels below the economic threshold at a relatively low cost to the grower. However, there are serious concerns surrounding the use of chemical insecticides including the development of resistance in insect populations, the banning of various insecticides, regulations for lowering of the maximum residue level and employee and consumer safety. For this reason, alternate measures of control are slowly being adopted by growers such as mating disruption, cultural methods and the use of baculovirus biopesticides as part of integrated pest management programmes. The reluctance of growers to accept baculovirus or other biological control products in the past has been due to questionable product quality and inconsistencies in their field performance. Moreover, the development and application of biological control products is more costly than the use of chemical alternatives. Baculoviruses are arthropod specific viruses that are highly virulent to a number of lepidopteran species. Due to the virulence and host specificity of baculoviruses, Cydia pomonella granulovirus has been extensively and successfully used as part of integrated pest management systems for the control of C. pomonella in Europe and around the world, including South Africa. Commercial formulations have been typically based on the Mexican strain of CpGV. However due to long-term multiple applications of CpGV and the reliance on CpGV in organic farming practices in Europe, resistance to the CpGV-M strain has developed in a number of field populations of C. pomonella. This study aimed to identify and characterize novel isolates of CpGV in South Africa and compare their virulence with the commercial standard CpGV-M. Secondly, since C. pomonella is difficult to culture on a large scale, an alternate method of CpGV production was investigated in order to determine if CpGV could be produced more efficiently and at a reduced cost without negatively impacting the quality of the product. Several isolates of CpGV were recovered either from field collected larvae or from a laboratory-reared C. pomonella colony. Characterisation of DNA profiles using a variety of restriction enzymes revealed that only a single isolate, CpGV-SA, was genetically different from the Mexican strain of the virus used in the commercially available CpGV based products in South Africa. In dose-response bioassays using CpGV-SA, LC₅₀ and LC₉₀ values for neonate C. pomonella larvae were 3.18 x 10³ OBs/ml and 7.33 x 10⁴ respectively. A comparison of these values with those of CpGV-M indicated no significant difference in the virulence of the two isolates under laboratory conditions. This is a first report of a genetically distinct CpGV isolate in South Africa. The biological activity and novelty of CpGV-SA makes this isolate a potentially important tool for CpGV resistance management in South Africa. In order to justify production of CpGV in an alternative host, studies on the comparative biological performance of C. pomonella and T. leucotreta based on oviposition, time to hatch, larval developmental times and rearing efficiency as well as production costs were performed. Thaumatotibia leucotreta was found to be more fecund and to have significantly shorter egg and larval developmental times. In addition, larval production per unit of artificial diet was significantly higher than for C. pomonella. This resulted in T. leucotreta being more cost effective to produce with implications for reduced insectary space, sanitation practices as well as the labour component of production. Virus yield data generated by inoculation both C. pomonella and T. leucotreta with nine concentrations of CpGV resulted in comparable virus yields, justifying the continuation of the research into production of CpGV in T. leucotreta. It was important to determine the LC and LT values required for mass production of CpGV in late instar T. leucotreta larvae. Dose- and time-response bioassays with CpGV-M were conducted on artificial diet to determine these values. Fourth instar LC₅₀ and LC₉₀ values were 5.96 x 10³ OBs/ml and 1.64 x 10⁵ OBs/ml respectively. LT50 and LT90 values were 81.10 hours and 88.58 hours respectively. Fifth instar LC₅₀ and LC₉₀ values were 6.88 x 10⁴ OBs/ml and 9.78 x 10⁶ OBs/ml respectively. LT₅₀ and LT₉₀ values were 111.56 hours and 137.57 hours respectively. Virus produced in fourth instar T. leucotreta larvae was bioassayed against C. pomonella neonate larvae and compared to CpGV-M to establish if production in the heterologous host negatively affected the virulence of the isolate. No significant difference in virulence was observed between virus produced in T. leucotreta and that produced in C. pomonella. The data generated in the bioassays was used in CpGV mass production trials to evaluate production. All production methods tested produced acceptable virus yields. To examine the quality of the virus product, genomic DNA was extracted from larval cadavers and subjected to REN analysis with HindIII. The resulting DNA profiles indicated that the virus product was contaminated with the homologous virus, CrleGV. Based on the above results, the use of T. leucotreta as an alternate host for the in vivo production of CpGV on a commercial basis is not at this stage viable and requires further investigation before this production methodology can be reliable used to produce CpGV. However, this study has shown that CpGV can be produced in a homologous host, T. leucotreta and significant strides have been made towards developing a set of quality control standards that are essential for further development of successful production methodology. Finally a novel isolate of CpGV has been identified with comparable virulence to the CpGV-M. This is an important finding as it has broad reaching implications for resistance management of CpGV products in South Africa.
Full Text:
Date Issued: 2015

Prioritising biological control agents for release against Sporobolus pyramidalis and Sporobolus natalensis (Poaceae) in Australia

Authors: Sutton, Guy Frederick
Date: 2021
Subjects: Grasses -- Diseases and pests , Bruchophagus , Wasps , Alien plants -- Biological control -- Australia , Sporobolus -- Biological control -- Africa , Sporobolus -- Biological control -- Australia , Insects as biological pest control agents -- Australia , Insects as biological pest control agents -- Africa
Language: English
Type: text , Thesis , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/172445 , vital:42201 , 10.21504/10962/172445
Description: Sporobolus pyramidalis Beauv. and S. natalensis (Steud.) Th. Dur. and Schinz. (giant rat’s tail grass) (Poaceae), invade rangelands and pastures in eastern Australia, costing the livestock industry approximately AUS$ 60 million per annum in grazing losses. Mechanical and chemical control options are costly and largely ineffective. Biological control is viewed as the most promising control option, however this management strategy has largely been avoided for grasses, due to their perceived lack of suitably host-specific and damaging natural enemies. In this thesis, the prospects for using biological control against S. pyramidalis and S. natalensis in Australia was assessed, in light of these potential challenges. Climate matching models were used to identify high-priority geographic regions within the plants’ native distributions to survey for potential biological control agents. High-priority regions to perform surveys were identified by modelling the climatic suitability for S. pyramidalis and S. natalensis in sub-Saharan Africa (i.e. their potential native ranges’), and climatic compatibility with regions where biological control is intended in Australia. High-priority regions for S. pyramidalis included: (1) coastal East Africa, ranging from north-eastern South Africa to Uganda, including south-eastern DRC, (2) some parts of West Africa, including inland regions of the Ivory Coast and western Nigeria, (3) northern Angola and (4) eastern Madagascar, and for S. natalensis included: (1) eastern South Africa, (2) eastern Zimbabwe, (3) Burundi, (4) central Ethiopia and (5) central Madagascar. Prospective control agents collected from these regions have the highest probability of establishing and proliferating in Australia, if released. In surveys of the insect assemblages on S. pyramidalis and S. natalensis in the climatically-matched region of eastern South Africa fifteen insect herbivores associated with the grasses were identified. Insect feeding guild, geographic distributions, and seasonal abundances suggest that three stem-boring phytophagous wasps, Tetramesa sp. 1, Tetramesa sp. 2 and Bruchophagus sp. 1 (Hymenoptera: Eurytomidae), have potential as control agents. Species accumulation curves indicated that additional surveys in South Africa are unlikely to yield additional potential control agents. Field host-range surveys of 47 non-target grass species in South Africa showed that Tetramesa sp. 1, Tetramesa sp. 2, and Bruchophagus sp. 1, were only recorded from S. pyramidalis and S. natalensis. Integrating field host-range with phylogenetic relationships between plant species indicated that no native Australian Sporobolus species or economic crops and pastures are expected to be attacked by these wasps. All three wasp species are predicted to be suitably host-specific for release in Australia. Three other endophagous herbivores attacked non-target native African Sporobolus species that share a close phylogenetic relationship to native Australian Sporobolus species, and therefore, demonstrate considerable risk of non-target damage. These species should not be considered as potential control agents. Under native-range, open-field conditions, Tetramesa sp. 1 caused an approximately 5-fold greater reduction in plant survival and reproductive output than Tetramesa sp. 2 and Bruchophagus sp. 1. Tetramesa sp. 1 in combination with Tetramesa sp. 2 did not significantly increase the level of damage, while Bruchophagus sp. 1 may decrease the efficiency of Tetramesa sp. 1, if released in combination. Tetramesa 1 is therefore the most promising candidate agent. Prioritising potential agents using predicted efficacy allowed otherwise equally suitable prospective agents to be prioritised in a strategic manner. Prioritising which natural enemies to target as biological control agents is a complex task. Field host range and damage assessments in the native range may provide more realistic data than typical studies performed under artificial conditions in a laboratory or quarantine. Moreover, it could assist practitioners in prioritising the most suitable agent(s) at the earliest stage in the programme as possible. This study demonstrated that grasses are suitable targets for biological control as they can harbour host-specific and damaging natural enemies.
Full Text:
Date Issued: 2021

Application of dermal microdialysis and tape stripping methods to determine the bioavailability and/or bioequivalence of topical ketoprofen formulations

Authors: Tettey-Amlalo, Ralph Nii Okai
Date: 2008
Subjects: Drugs -- Therapeutic equivalency Transdermal medication High performance liquid chromatography Nonsteroidal anti-inflammatory agents -- Bioavailability Nonsteroidal anti-inflammatory agents -- Effectiveness Nonsteroidal anti-inflammatory agents -- Testing Nonsteroidal anti-inflammatory agents -- Side effects
Language: English
Type: Thesis , Doctoral , PhD
Identifier: vital:3796 , http://hdl.handle.net/10962/d1003274
Description: The widespread acceptance of topical formulations intended for local and/or regional activity has prompted renewed interest in developing a model to determine the bioavailability of drugs in order to establish bioequivalence as a means of evaluating formulation performance of multisource products and also for use during formulation development. Current in vivo techniques such as blister suction and skin biopsy amongst others used to determine the bioavailability and/or bioequivalence of topical formulations are either too invasive to generate appropriate concentration-time profiles or require large numbers of study subjects thereby making the study expensive and time-consuming. Moreover, there are currently no sampling techniques that can demonstrate dermal bioavailability and/or bioequivalence of topical formulations intended for local and/or regional activity. Dermal microdialysis is a relatively new application of microdialysis that permits continuous monitoring of endogenous and/or exogenous solutes in the interstitial fluid. The technique is involves the implantation of semi-permeable membranes which are perfused with an isotonic medium at extremely slow flow rates and collection of microlitre sample volumes containing diffused drugs. Tape stripping, a relatively older technique, has been extensively used in comparative bioavailability studies of various topical formulations. However, due to shortcomings arising from reproducibility and inter-subject variation amongst others, the published FDA guidance outlining the initial protocol was subsequently withdrawn. The incorporation of transepidermal water loss with tape stripping has garnered renewed interest and has been used for the determination of drug bioavailability from a number of topical formulations. Hence the primary objective of this research is to develop and evaluate microdialysis sampling and tape stripping techniques, including the incorporation of the determination of transepidermal water loss, to assess the dermal bioavailability of ketoprofen from topical gel formulations and to develop models for bioequivalence assessment. A rapid UPLC-MS/MS method with requisite sensitivity for the analysis of samples generated from dermal microdialysis was developed and validated which accommodated the microlitre sample volumes collected. An HPLC-UV method was developed and validated for the analysis of samples generated from the in vitro microdialysis and in vivo tape stripping studies. The work presented herein contributes to a growing body of scientific knowledge seeking to develop a model for the determination of bioequivalence of pharmaceutically equivalent topical formulations intended for local and/or regional activity in human subjects.
Full Text:
Date Issued: 2008

Showing items 201 - 220 of 2208

The National Skills Fund and green skills: towards a generative mechanism approach

Studies of the population structure and generic diversity of domesticated and "wild" ostriches (Struthio camelus)

Bush clumps as indicators of thresholds of change in Arid Thicket mosaic piospheres

A social realist account of the tutorial system at the University of Johannesburg

A systems approach to mainstreaming environment and sustainability in universities : the case of Rhodes University, South Africa

Assessment of the implementation of the National Certificate (Vocational) plant production modules

Plastochron index - an indicator of plant structure and function a case study using Pisum sativum L

Challenging desire : performing whiteness in post-apartheid South Africa

Towards a norm of compliance in recreational fisheries

Nonlinear optical responses of targeted phthalocyanines when conjugated with nanomaterials or fabricated into polymer thin films

The assembly of p-aryl triazole foldamers into double and other super- helical structures

Ammophila arenaria (L.) Link (marram grass) in South Africa and its potential invasiveness

Culturally-informed coping strategies of posttraumatic stress disorders among the black Africans in the greater Accra region of Ghana and black Africans in the eastern cape of South Africa

The investigation, development and characterisation of novel zirconium-based tanning agents

Characterisation of Trypanosomal Type III and Type IV Hsp40 proteins

Application of computational methods in elucidating the isomerization step in the biosynthesis of coumarins

The role of conflict management in maintenance of discipline : the case of Kenya's public secondary schools

Production of Cydia pomonella granulovirus (CpGV) in a heteralogous host, Thaumatotibia Leucotreta (Meyrick) (False codling moth)

Prioritising biological control agents for release against Sporobolus pyramidalis and Sporobolus natalensis (Poaceae) in Australia

Application of dermal microdialysis and tape stripping methods to determine the bioavailability and/or bioequivalence of topical ketoprofen formulations