List of Titles

Analysis of the role of Hsp90 in colon cancer and cancer stem-like cell biology in vitro using a genetically paired cell line model

Authors: Slater, Cindy
Date: 2015-04-09
Subjects: Uncatalogued
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/480345 , vital:78433
Description: Colon cancers are commonly associated with mutations or changes in signaling in the Wnt/β-catenin pathway. Cancer treatments, such as chemotherapy and radiation, are challenged by the limited methods of disease detection and the insufficient elimination of contributing factors, such as cancer stem-like cells (CSC), to metastatic disease. CSC are characterised by their ability to survive anchorage-independently and attribute to therapeutic resistance. To examine the biological changes associated with the progression of human colon cancers and the role of Hsp90 in cancer and CSC biology, SW480 and SW620 genetically paired (isogenic) colon cancer cell lines from the same patient were characterised for populations of putative CSC, tumoursphere (TS) forming ability, cell growth, behaviour and response to anti-cancer therapeutics. The SW480 cell line was established from a primary colon adenocarcinoma and the SW620 was established from a lymph node metastasis of the primary cancer one year later. To address the role of Hsp90 in colon cancer, the sensitivity of cells and TS were analysed in response to geldanamycin and novobiocin, and an isoform-specific approach to the targeting of Hsp90α was developed. Flow cytometric analysis of putative CSC by phenotype revealed variable proportions of cells bearing the CD44+/CD133+ surface protein marker, widely used in the identification of colon CSC, in SW480 and SW620 cells. The paired cell lines maintained similar proportions of putative CSC, identified by the expression of the ABCG2 protein (side population; 1 %) and through high aldehyde dehydrogenase activity (ALDEFLUOR; 6 %). SW480 cells demonstrated greater TS forming efficiency than SW620 cells (49.9 and 35.5 %, respectively) and observations of wound-healing showed SW480 cells to be more migratory than SW620 cells. No difference in response to Hsp90 inhibition was observed between paired cell lines, however SW480 TS resisted treatment with geldanamycin. This the first study to report a dose-dependent increase in TS growth in response to novobiocin inhibition of Hsp90, and to demonstrate that that the sensitivity of SW480 and SW620 TS to oxaliplatin, a common drug for the treatment of metastatic colon cancers, was enhanced by novobiocin, providing promise for the elimination of CSC with combined chemotherapeutics. We analysed the Wnt/β-catenin pathway in response to expression of short hairpin RNA (shRNA) against Hsp90α or a control non-targeting shRNA, under the control of a tetracycline-responsive promoter. Hsp90α knockdown contributed to a deregulated stress response, presenting with reduced Hsp27 and β-catenin protein, but corresponded to an increase in the association between Hsp90, β-catenin and Hsp27 in vitro. The reduction of Hsp90α did not influence sensitivity of the colon cancer cells to activators or inhibitors of the Wnt pathway, but rather correlated to reduced TS formation, cell adhesion and spreading, identifying potential therapeutic benefit to the controlled reduction of Hsp90α for the deregulation of colon cancer characteristics. Given that Hsp27 and β-catenin are both involved in cell adhesion, cytoskeletal dynamics and interact directly with each other, we propose a role for targeting Hsp90α in the regulation cell adherence indirectly via reductions in levels of β-catenin and Hsp27, rather than by modifying the transcriptional activity of β-catenin. , Thesis (PhD) -- Faculty of Science, Biochemistry and Microbiology, 2015
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Date Issued: 2015-04-09

Systematics and phylogeography of mormyrid fishes in South Africa

Authors: Maake, Pholoshi Abram
Date: 2015-04-09
Subjects: Uncatalogued
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/480323 , vital:78431
Description: Two genera of mormyrids have been reognised from South Africa. Marcuseniusis the largest genus of the Mormyridae, comprising 38 species distributed throughout tropical and sub-tropical Africa. In southern and eastern Africa eight species have been recognized, including M. pongolensis from South Africa. Petrocephalushas about 30 species distributed mainly in tropical Africa, and 15 of these were recently identified in southern and eastern Africa.This thesis integrated several techniques, through the collection of complementary, but separate data sets to investigate the phylogeography of M. pongolensis in South Africa, and the systematics, evolutionary history, biogeography of Marcusenius and Petrocephalusfishes in southern and eastern Africa. Mitochondrial and nuclear genetic markers consistently demonstrated strong population structuring and identified three divergent lineages within South Africa. The widespread Pongola Lineage occurs partly in the Limpopo River system, and is very common in the Incomati, Pongola (type locality) and Kosi river systems. The Limpopo Lineage endemic only in the Limpopo River system is monophyletic with the Mhlatuze-Nseleni Lineage which is only known from the Mhlatuze and Nseleni rivers in the south. There was strong indication of historical isolation, in the form of allopatric fragmentation between genetically divergent Limpopo and Mhlatuze-Nseleni lineages. High genetic diversity was observed in the Limpopo River system within the Limpopo Lineage and the Pongola Lineage. The occurrence of the Mhlatuze-Nseleni Lineage in the far south cannot be explained by the hypothesis of confluence of rivers, river capture or episodic drainage connections, as the Mhlatuze and Nseleni Rivers would not have had a common confluence or shared low relief terrain with the Limpopo, Incomati, Pongola or Kosi river systems. Morphological studies of these lineages revealed even more differentiations and were described as: Marcuseniuskrameri sp. nov. for the Limpopo Lineage, and M. caudisquamatus sp. nov. from the Mhlatuze and Nseleni river systems. The specimens from the Ruvuma River were also well differentiated from all southern and eastern African species of Marcusenius, and were therefore recognised as M. lucombesisp. nov. New diagnosis characters of M. pongolensis were re-described and akey to the southern and eastern African species of Marcuseniuswas also provided. The results of all phylogenetic approaches that included all known southern and eastern AfricanMarcusenius species are highly congruent and provided very strong support for recognizing Marcuseniusspecies from these regions as a monophyletic assemblage that evolved from a single common ancestor. The southern and eastern African Petrocephalus is divided into two deeply mitochondrial and nuclear divergent Western and Eastern groups that are separated by the Victoria Falls. The phylogenetic relationships within each group were not supported and future studies incorporating more molecular characters andspecies will likely help to resolve the relationships. Speciation within Marcusenius and Petrocephalus ranges in the focus of at least 0.8-5 Million years ago in agreement with geological data, which suggested that vicariant events associated with the formation of the major river systems played a major role in the evolution and distribution of both genera in southern and eastern Africa. The high degree of genetic differentiation and at least four previously undescribed lineages recovered in this study suggested that mormyrid diversity within southern and eastern Africa may be underestimated. Possible threats to the studied mormyrid species and lineages and other freshwater-dependent species were identified during the course of this study. When described, the unidentified lineages would further increase the species diversity of both Marcusenius and Petrocephalus,and, therefore, the southern and eastern African ichthyofauna. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2025
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Date Issued: 2015-04-09

Exploring pre-service teachers’ reflective practice in the context of video-based lesson analysis

Authors: Chikiwa, Samukeliso
Date: 2020-04-30
Subjects: Uncatalogued
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/355357 , vital:64492
Description: This study explored the development of reflective practice in foundation phase pre-service teachers in the context of video-based lesson analysis at a university in South Africa. The study was conducted in the field of mathematics education, responding to the urgent need to equip pre-service South African teachers with the knowledge and skills for effective mathematics teaching. The research is foregrounded by the continuing poor performance of South African learners in mathematics at all levels of education in the country, which has been linked to the inadequate knowledge and skills of mathematics teachers. Pre-service teacher education is putting considerable effort into improving the preparation of mathematics teachers and developing their ability to reflect on their teaching practice is one of the strategies being employed for this purpose. Research has demonstrated the importance of reflective practice (RP) in both developing and extending teachers’ mathematical knowledge for teaching. This study therefore contributes to current research that supports the development of RP as a professional skill for promoting the acquisition of knowledge for teaching in pre-service teacher education. The study adopted a qualitative case study approach with two phases of data collection. In Phase 1 I collected and analysed three sets of 19 pre-service teachers’ written reflections to establish the nature of the reflections that they developed when analysing video-recorded mathematics lessons of experienced teachers’ practice. Phase 2 was conducted with four PSTs who reflected on video-recorded mathematics lessons of their own practice, and similarly sought to investigate the nature of the reflections they developed when reflecting on practice. The four PSTs wrote one set of reflections on their own lessons, went through three sessions of facilitator-guided reflections, then wrote another set of reflections to establish if the support provided in small group facilitator-guided sessions improved their reflections. Iterative content analysis was employed to analyse the PSTs’ written reflections, using an analytic tool that I developed for this purpose through merging Lee’s (2007) and Muir and Beswick’s (2007) levels of reflection frameworks. My model had four levels of reflection: description, explanation, suggestion and reflectivity. The names of each of the levels connect to the key indicator for that level. PSTs’ written reflections were coded and analysed according to these levels. The study found that PSTs’ initial reflections were mostly description of general classroom events with little reflection at the levels of explanation and suggestion, and an absence of reflectivity. Most reflections focused on general events in the lesson rather than mathematical events, even though the six lens framework they were given to guide their reflections prompted them to steer their attention towards mathematical events. The second and third sets of reflections, although mostly still at level 1, showed some shifts towards explanation and suggestion, although an increased focus on mathematical events though reflectivity was still largely absent. No PST reached the fourth level of reflectivity in Phase 1. However, in Phase 2, the PSTs’ reflections after the three small group facilitator-guided sessions included some evidence of reflectivity. The findings suggest the need for pre-service teacher educators to make a concerted effort to teach PSTs what reflection is and how to reflect on their practice. The findings also showed the need for small group facilitator-guided support in the development of PSTs’ reflective practice. , Thesis (PhD) -- Faculty of Education, Education, 2020
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Date Issued: 2020-04-30

Maternal health care services in waiting mothers’ shelters: the case of Mawadza village in Bonda, Manicaland, Zimbabwe

Authors: Muchabveyo, Brenda Hamufari
Date: 2021
Subjects: Pregnant women Zimbabwe Manicaland Province , Women's shelters Zimbabwe Manicaland Province , Maternal health services Zimbabwe Manicaland Province , Integrative medicine , Childbirth Social aspects Zimbabwe Manicaland Province
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/476912 , vital:78017 , DOI 10.21504/10962/476912
Description: This study explores the experiences and perceptions of expectant mothers during prenatal, intra-, and postpartum care. It focuses on expectant mother‘s use or non-use of a waiting mothers' shelter within a medical pluralistic village within a context where hospitals and maternal health care facilities are not proximate. Special focus was on Mawadza village in the Mutasa district in Manicaland Province of Zimbabwe. A sample of 48 participants was used for collecting data in this study. The sample consisted of 15 women some of whom were expectant mothers in the waiting mothers‘ shelter (11) and others had used (4) the shelter once or twice since 2015. Participants were drawn mainly from Mawadza village and Bonda Mission Hospital while others were from the district and provincial offices of the Ministry of Health and Child Care of Zimbabwe. The study adopted a qualitative research methodology, which employed in-depth interviews; key informant interviews (KIIs) and focus group discussions (FGDs) as the main data gathering strategies. In-depth interviews were conducted with the expectant mothers and those who had formerly used the shelter since 2015, while, key informant interviews were conducted with the hospital staff members, traditional healers and the midwives from Mawadza village. Focus group discussions were also conducted with both male and female community members from Mawadza village. The study carried out face to face interviews and notes were handwritten and transcribed at the end of each day. Data coding was used to analyse data. The paradigms and theoretical underpinnings of the study were influenced by the symbolic interactionist theory. The theory made it possible to understand the social processes of pregnancy and childbirth in the waiting mothers' shelter due to its interpretive approach to social research and the legitimacy it places on the social interaction and meanings that social actors place on interactions in their environments. The study documented the ways pregnancy and childbirth are perceived, understood, and experienced in Mawadza village within the context of medical pluralism. In Mawadza village, pregnancy and childbirth are highly embedded in the cultural beliefs of the local people, hence, treated with importance and assumed important symbolic meanings. On the contrary, the waiting mothers‘ shelter as a biomedical facility handles pregnancy and childbirth from a biomedical approach, basing its practices and operations on pure science. Expectant mothers who await labour in this facility are therefore involved in several biomedical activities during prenatal, intra- and post-partum care in the waiting mothers‘ shelter. The need to access skilled birth attendants and the criminalisation of home births in Mawadza village have been the major reasons that influence the expectant mothers to use the waiting mothers‘ shelter. Nevertheless, factors such as medical pluralism, child care, and family commitments, lack of understanding of the importance of the waiting mothers‘ shelter, lack of privacy in the shelter, and cost of food and utilities during the expectant mothers' stay in this facility among others are factors that deter expectant mothers from using the waiting mothers' shelter. Lack of practice of bodily agency where practices common in preparation for childbirth such as opening the birth canal which is not accepted was also reported among common problems that discourage expectant mothers from preferring use of the shelters. The study also revealed that the community is involved in the operations of the waiting mothers‘ shelter, although, the involvement is gendered since there are more women involved as compared to men. The study concluded that even biological processes such as pregnancy and childbirth can only be fully understood within a social context given the different meanings which are attached to the various aspects of the childbirth process by the various actors such as expectant mothers, mothers, biomedical practitioners, traditional healers and communities in Mawadza village. Also, in a medical pluralistic village, the different health care providers who deal with pregnant women do not necessarily conflict as evidenced by the complementary role of these two (complementary insofar as they achieve collectively desired outcomes, albeit in parallel and (mutually) exclusive means) in caring for women during pregnancy and childbirth. , Thesis (PhD) -- Faculty of Humanities, Sociology, 2021
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Date Issued: 2021

Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa

Authors: Memela, Sinenhlanhla
Date: 2021-04-28
Subjects: Land use South Africa Makhanda Decision making , Land use, Urban South Africa Makhanda Decision making , Residential real estate South Africa Makhanda , Urban ecology (Sociology) South Africa Makhanda , Urban gardening South Africa Makhanda , Urban livestock production systems South Africa Makhanda
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/322694 , vital:60589 , DOI 10.21504/10962/322694
Description: This study seeks to understand land use decision-making dynamics on large residential plots in Fingo Village, Makhanda (Grahamstown). Fingo Village was selected as a study area because it is one of the poorest urban settings in South Africa where urban poverty is observed alongside access to land. A dominant economic perspective not only suggests that land use decisions are motivated by economic motives, but also implies that access to land would enable people to generate income from its use to improve their livelihoods. This study argues against an uncritical embrace of this assumption. Lefebvre’s production of space thesis provides a holistic understanding of the factors involved in the making of land use decisions. The focus of this study is on the dialectic process in the spatial triad– spatial practice, representational space and representations of space. This involved the reading of government policies and legislation together with local lived experiences to gain an understanding of the particular spatial practices seen in Fingo Village. Snowball and convenience sampling were used to select 36 household plots in Fingo Village. Primary data was gathered by means of semi-structured interviews and participatory mapping while additional information was sourced from secondary sources and desktop analysis. The findings of the study show that there is no uniform pattern of land use and success. Different land use activities found on the selected residential plots, including the main house, backyard flat or flats, spaza shops, a funeral parlour, livestock keeping, cultural use (a kraal for ancestral worship) and food gardening. These activities are motivated by residents’ perceptions and attitudes towards their spaces, as well as the value and meaning they attach to the land which is not limited to economic factors, but is also influenced by socio-cultural, political and biophysical considerations. Although some spatial practices are prohibited by the government, they are important to the residents. Other participants fail to use the land as would be expected by a conventional economic perspective, due to spatial conflict relating to different interests as a result of collective land ownership and the failure of municipalities to enforce policies and regulations. The fact that numerous factors influence households’ land use decisions means that access to land does not always directly translate into economic benefits. It is all about what people think or do about their land, as well as what the state lays out in terms of policy and legislation, that will influence whether those people with large plots of land will ‘prosper’ or not. , Thesis (PhD) -- Faculty of Science, Geography, 2021
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Date Issued: 2021-04-28

Constraints and enablements on quality improvement in higher education

Authors: Browning, Leanne Elizabeth
Date: 2021-10-29
Subjects: Education, Higher Aims and objectives South Africa , Education, Higher Evaluation , Quality assurance South Africa , Educational evaluation South Africa , Self-evaluation , Critical realism
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294956 , vital:57273 , DOI 10.21504/10962/294956
Description: This study contributes to the literature on quality improvement in higher education by examining the structural, cultural and agential constraints and enablements on a quality process at a university in South Africa. It examined four cases and developed an understanding of the complex interaction of structure, culture and agency and the mechanisms that enable or constrain quality improvement in higher education. The study drew on the literature on higher education quality for the theoretical basis for what is known contributes to the way in which quality assurance and improvement is implemented and its impact on the higher education context. Critical Realism provided the ontological framework and conceptual tools to understand and explore the complex social world within which the quality process took place. The literature on the morphogenetic approach provided the analytical framework for the data analysis and findings. The data consisted of a set of documents from a quality process that took place over a five-year period. The data analysis revealed that different departmental contexts impact on how mechanisms are activated. Each school context shapes the way in which people engage with the review process and consequently, processes and procedures are mediated in each context. This research therefore adds to the understanding of the way in which quality processes take place at a micro-level within an institutional context and informs the approach to quality improvement more broadly, nationally and internationally. The research contributes to the knowledge that will inform planning, policies and practices in quality improvement processes in higher education and the findings identify a number of factors (mechanisms) that should inform the way in which a quality process is facilitated, will enable effective self-evaluation and review processes, and consequently are more likely to lead to quality improvement. , Thesis (PhD) -- Faculty of Education, Centre for Higher Education Research, Teaching and Learning, 2021
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Date Issued: 2021-10-29

Culture, gender and forests: social differentiation in coping and adapting to climate change and other stressors in the south west and east regions of Cameroon

Authors: Enokwena Baa, Ojongetakah
Date: 2021-10-29
Subjects: Climatic changes Cameroon , Differentiation (Sociology) Cameroon , Climatic changes Social aspects Cameroon , Cultural awareness Cameroon , Environmental justice Cameroon , Social justice Cameroon , Environmental risk assessment Cameroon , Political ecology Cameroon , Ecofeminism Cameroon , Social capital (Sociology) Cameroon , Community forests Cameroon , Deforestation Cameroon
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/295040 , vital:57284 , DOI 10.21504/10962/295040
Description: Climate change adaptation scholars and practitioners are beginning to acknowledge that the impact of climate change and other related shocks and stressors will be felt, and reacted to, differently across genders and other types of intersecting social categories, such as age, wealth, and culture, in rural communities. However, to date, most research unpacking these differential impacts and responses has been limited to 'men' versus 'women'. Few studies go beyond this male-female dichotomy to include the different gender structures of households and the intersection with other social factors that contribute to marginalisation, such as ethnicity. This research aimed to explore how different gendered household types in two ethnically diverse communities, the Ejagham and the Baka communities in the SSouth West and East regions of Cameroon, experienced and responded to climate change and other stressors. The central argument of the study is that social differentiation present dynamics and complexities across intersecting identities which determines varied levels of vulnerabilities, adaptive capacity, and livelihood outcomes. The study thus sets out to examine cultural and gendered differentiation in household assets and livelihood activities, how multiple shocks and stressors are experienced, and the differentiated responses to these, focussing specifically on forest and social safety nets. The findings were used to develop an integrated understanding of the complex socially differentiated dimensions of vulnerability and adaptation within the two communities and the implications for more climate secure and equitable livelihoods. The study drew on social-ecological systems, social justice, and feminist political ecology as guiding theoretical lenses. The study further integrated the Moser gender planning and Harvard analytical frameworks as tools for unpacking gender inequality. It followed a mixed methods research design that included household surveys, key informant interviews, and focus group discussions that applied participatory exercises. Financial, human, and physical capital were arguably limited within all household types in both the Ejagham and the Baka communities. Social and natural capital were the most common form of assets that households relied on, with ‘savings groups’ in the Ejagham communities being particularly prevalent. Most households were involved in crop cultivation and forest product collection although there were gendered and cultural differences. Collection of wild fruits, medicinal plants, and condiments, for example, was a more common livelihood activity within the Baka communities and amongst female-headed households. Cultivation of pumpkins and vegetables was dominant amongst households in Ejagham, with these being grown mainly by women, while the cultivation of yams was done by men. Across both communities, female-headed households had less ownership of land compared to male-headed households. The current pressure on agricultural land in the Ejagham communities has decreased crop productivity, with female-headed households disproportionately affected by less ownership of land and thus, options to diversify agricultural activities. Similarly, the rise in individual and private land ownership, in response to resource scarcity and large-scale deforestation in East Cameroon, has further dispossessed female-headed households in the Baka communities, already marginalised by their ethnicity, of land. Inequitable access to assets and the disparity in ownership of these assets across the study communities was both a cause and effect of households' differential livelihood activities and responses to shocks and stressors. Several of the shocks and stressors households were exposed to differed across the two sites. The Ejagham communities, being predominantly agricultural, frequently identified warming temperatures as a climatic stressor and increased sensitivity to the impacts of these. The Baka faced similar climate stressors, although more frequent storms were mentioned as a shock by a significant number of households. The impacts of these storms include damage and destruction of houses due to the traditional construction methods used. Since women are often tasked with the building of houses this adds another layer of stress for them. In terms of idiosyncratic shocks, the death of the main breadwinner was most frequently reported in both communities as a non-climatic shock, although this was higher within the Ejagham communities than in the Baka communities, and particularly so for female-headed households. The varied experiences from multiple shocks and stressors resulted in households' differential coping and adaptation responses. Among the different response options, social and forest safety nets, especially the use and sale of forest products (NTFPs) remained the main response options used by households in both communities. Forest products further supported households during periods of food shortage, especially female-headed households in the Ejagham communities. Households further supported one another through social groups such as savings, farming, hunting (particularly for men) and NTFP collection (for women) groups. By exploring social-ecological interactions, the study highlights the complexities around gender inequalities, vulnerabilities, and responses across socially differentiated groups of people which should be considered in policy, practice, and research. Several of my findings challenge mainstream discourses that generally group women, for instance, as a homogenous category when looking at vulnerability. For example, findings revealed that it is possible for different types of households, both women and men, to be both advantaged and vulnerable at the same time, depending on the shock or stressor faced and the livelihood activities they engage in. The same also applies to ethnicity. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
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Date Issued: 2021-10-29

Integrative systematic structuring of the widespread psammophiid snakes (Psammophiidae): a multi-evidence species delineation approach

Authors: Keates, Chad
Date: 2021-10-29
Subjects: Psammophis South Africa , Herpetology , Herpetology Africa , Molecular biology , Psammophis Classification , Psammophis Genetics , Psammophis Morphology , Psammophis Phylogeny , Morphology Mathematics , Psammophylax
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/295077 , vital:57288 , DOI 10.21504/10962/295079
Description: Species form the foundations upon which we build our understanding of the natural world. Although a focus of much scientific attention, our understanding of species is stunted by the intrinsic ‘fuzziness’ of boundaries within nature. Due to the complexity of the evolutionary process, coupled with an ever-changing abiotic landscape, species are hard to delineate, even at the best of times. Whilst various species concepts and sophisticated delimitation methods have helped scientists tease apart species, many species complexes persist. This is because taxonomy is a discrete ordering system imposed upon the continuous and intercalated structure of life. To improve our understanding of a wide-ranging family of snakes, I investigated the taxonomy and evolutionary structuring within Psammophiidae using both molecular and morphological approaches, employing phylogenetic, phylogeographic, and morphometric analyses on the group. The systematic complexity of the family (as evidenced by past research) coupled with the group’s widespread distribution and ecological importance, made the taxon an ideal candidate for a broad-sweeping multi-level systematic analysis using multiple species delimitation methods. Additionally, in this thesis I attempted to build on the ground-breaking work of Christopher Kelly by addressing several knowledge gaps identified within the family, and in so doing, produce the most thorough evolutionary and taxonomic study of Psammophiidae possible. Given the taxonomic uncertainty associated with the family, Chapter Two used a representative sampling from every available species (near complete taxon sampling approach) in the family. The chapter used both standard and time-calibrated phylogenetic modelling and distance/threshold-based species delimitation, to elucidate the finer-level structuring within the family. Geometric morphometrics was used to determine whether there were diagnosable differences in head structure between the different genera. The final phylogenetic tree incorporated 320 samples, representing the most comprehensive phylogenetic reconstruction of the family to date. By using a near-complete taxon sampling approach, I was able to resolve previously unsupported relationships within the family whilst also identifying several novel instances of an under- and over-appreciation of species diversity within the family. Geometric morphometrics also identified clear distinctions between genera based on head shape (head width and ‘beakedness’). This chapter showcased the importance of complete taxon sampling and robust methodology for species delimitation and the deleterious effect of species concepts when implemented in isolation. In Chapter Three, I narrowed the scope of the study to focus on the genus level. Psammophylax (Fitzinger 1843) is an abundant, yet poorly studied genus of grass snakes, endemic to Africa. The generalist nature of the genus and wide-spanning distributions of the constituent species has given rise to several subspecies and a poor understanding of the taxonomic structuring within the genus. The overlapping distributions (sympatry) of many of Psammophylax species, coupled with the potential for cryptic speciation via mechanisms such as convergent evolution, made the group the ideal candidate for a broad-sweeping systematic study (as evidenced in Chapter Two). By applying the suite of analyses used in Chapter Two to the generic level, we aimed to determine the effectiveness of a multi-evidence species delineation approach when tackling systematic problems at lower taxonomic levels. A genetic phylogeny of six of the seven species was estimated using multiple phylogenetic and distance/ threshold-based species delimitation methods. To support the molecular analyses, we conducted morphological analyses on the body (traditional morphology) and head (geometric morphometrics) separately. Phylogenetic analyses recovered a similar topology to past studies, but with better resolution and node support. I found substantial genetic structuring within the genus, supported by significantly different head shapes between Ps. a. acutus and other Psammophylax species. Psammophylax a. acutus was recovered as sister to its congeners, and sequence divergence values and morphometrics supported its recognition as a new genus. Increased sampling in East Africa (Tanzania, Kenya, and Ethiopia) revealed that Psammophylax multisquamis is polyphyletic, necessitating the description of a new, morphologically cryptic, species from northern Tanzania. The distribution of Ps. multisquamis sensu stricto is likely restricted to Kenya and Ethiopia. Within this chapter, taxon-specific phylogenetic analyses yielded stronger intrageneric support as compared to Chapter Two, allowing for more defensible conclusions about taxonomical amendments. Geometric morphometrics proved similarly useful (as compared to Chapter Two) in teasing apart genera within the family but lacked the robustness to delineate species within Psammophylax with confidence, highlighting the apparent convergence of form within the genus. In Chapter Four, I investigated the evolutionary structuring within the Southern African endemic Psammophylax rhombeatus. The structural and environmental heterogeneity within the region has given rise to many morphological forms distributed throughout the country, with previous studies neglecting the associated molecular significance of these forms. Irrespective of their small sample sizes, both Chapter Two and Three identified substantial phylogenetic structuring within the species, making Ps. rhombeatus the ideal candidate for a multi-faceted systematic review, using a combination of phylogenetics, geometric morphometrics and, for the first time in this species, phylogeographic analyses. By investigating a single species, in detail, I was able to assess the effectiveness of the methodologies implemented in previous chapters on systematic sorting using the multi-evidence species delineation approach. Phylogenetic and haplotype analysis retrieved four well-supported clades: southeast South Africa (SESA), southwest South Africa (SWSA), north-eastern South Africa (NESA) and western South Africa (WSA). Although not variable enough to warrant taxonomic re-evaluation, the clades represented important genetic hotspots, with relatively high intraspecific genetic divergence values separating them, irrespective of the small geographic distances separating populations. This is likely a product of the taxon’s habitat-generalist lifestyle, enabling them to bypass vicariant barriers that might otherwise cause speciation in less versatile species. The clades are also geographically distinct, with little overlap, indicating previous vicariance, a finding that is supported by the split of Ps. rhombeatus from Ps. ocellatus in the mid-Pliocene, followed by the diversification of Ps. rhombeatus into four clades throughout the Pleistocene. The genetic structuring observed in Ps. rhombeatus may be a product of population expansion following ancient refugial isolation (potentially Last Glacial Maximum [LGM]). The molecular distinctiveness of the clades was not replicated in the morphological component of this chapter, with neither dorsal nor lateral geometric morphometric analyses of head shape showing any discernible distinctiveness based on geography. Whilst head shape has not been shown to be an effective delineator of evolutionary units at the species level (within this taxon), body colour, scalation, and snout-vent length has been linked to morphotypes within the species based on the work of Broadley (1966). These morphological groupings are loosely attributable to the molecular clades identified in the phylogenetic analyses, highlighting the complex interplay of genetic and morphological characteristics in the process of speciation, and their representation in systematic accounts. This thesis represents the most thorough evolutionary and systematic study of the family currently possible. In addition to identifying and describing both a new genus and species, this thesis also highlighted several instances of an over- and under-appreciation of species diversity within Psammophiidae. By applying a multi-evidence species delineation approach to this thesis, I show the intricacy of the evolutionary process (at various taxonomic levels) and showcase the ease to which species boundaries can be confounded when species concepts are implemented in isolation. These findings also highlighted the importance of sample size, sample range, species delimitation method on the outcome of taxonomic analyses, and their interpretation. Lastly, this thesis addressed the knowledge gaps left by Christopher Kelly’s PhD work and investigated the findings of recent papers that attempted to do the same. Whilst this study answers the questions of old, the taxon-intensive focus revealed several new knowledge gaps within the family, highlighting how much we know about snake systematics, and furthermore, how much we still need to learn about evolutionary structuring. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2021
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Date Issued: 2021-10-29

A wideband spectropolarimetry study of the spatially resolved radio galaxies: Cygnus A & Hydra A

Authors: Sebokolodi, Makhuduga Lerato Lydia
Date: 2022-04-04
Subjects: Radio astronomy , Radio galaxies , Faraday effect , Astrophysical spectropolarimetry , Intracluster medium , Cosmic magnetic fields
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/454415 , vital:75342 , DOI 10.21504/10962/454415
Description: This study presented results from our deep, wideband, high-spectral and high-spatial-resolution polarisation observations of the two most powerful radio galaxies, namely Cygnus A and Hydra A, with the Jansky Very Large Array (JVLA). The high surface brightness and strong polarisation of these radio sources enabled detailed polarimetric imaging, providing images at 0.75′′ resolution across 2−18 GHz and 2000 independent lines-of-sight across Cygnus A, and images at 1.5′′ (2 − 12 GHz) and 600 lines-of-sight across Hydra A. Our data revealed significant depolarisation and depolarisation structure, as well as deviations from a _2-law. We also found complicated structures in the Faraday spectra ranging from single-peaked to blended/resolved double- and multiple-peaked. The Faraday spectra of Hydra A were more multiple-peaked than Cygnus A. The fractional polarisation increased monotonically with increasing resolution, as expected. However, there were numerous lines-of-sight with complicated behaviour. We also found that the structure and complexity in the depolarisation increased at lower resolutions, suggesting substantial spatial structures across the lobes/tails. We fitted the 0.3′′ (6−18 GHz) and 0.50′′ (6−12 GHz) images of Cygnus A and Hydra A, respectively, with a simple model incorporating random, unresolved fluctuations in the cluster magnetic field to determine the high-resolution, high-frequency properties of the sources and the cluster. We found rotation measures (RM) between −5000 rad m−2 and +6400 rad m−2 across Cygnus A, and −2000 rad m−2 and +11900 rad m−2 across Hydra A, consistent with previous studies. From these derived properties, we generated predicted polarisation images of the sources at lower frequencies (< 6 GHz), convolved to 0.75′′ for Cygnus A and 1.5′′ for Hydra A. The predictions were remarkably consistent with the observed emission in both sources, providing strong support for the depolarisation being a result of unresolved fluctuations in the magnetic fields. We fitted various analytical models to the wideband data. We found that the data for both sources were inconsistent with a wholly mixed gas of thermal and synchrotron gas, particularly for regions withRM > 1000 rad m−2. Instead, the data required a dominant Faraday rotating screen in the foreground of the radio sources. The wideband modelling also showed preference towards models with at least two or more unresolved Faraday rotating patches. Single depolarising models fail to describe the data. This implies the presence of more than one depolarising screen in the vicinity of these sources. The observations were consistent with the lower-frequency depolarisation due to unresolved fluctuations on scales ≳ 300−700 pc in the magnetic field or the electron density superposed on a partially ordered field component. Both the large-scale magnetic fields and unresolved magnetic field fluctuations are external to the radio emission. The magnetic fields around Cygnus A are located in the ambient cluster gas, the shocked gas in the boundary of the lobes or both, while the magnetic fields around Hydra A are most likely located in the ambient cluster gas. , Thesis (PhD) -- Faculty of Science, Physics, 2022
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Date Issued: 2022-04-04

A framework for the economic valuation of wetland rehabilitation: case studies from South Africa

Authors: Browne, Michelle
Date: 2022-04-06
Subjects: Wetland restoration South Africa , Wetland management South Africa , Ecosystem management South Africa , Ecosystem services South Africa , Ecosystem management Economic aspects South Africa , Wetland restoration Cost effectiveness South Africa
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/263560 , vital:53638 , DOI 10.21504/10962/263561
Description: Wetlands are recognised as having the potential to contribute long-term benefits to society; wetland rehabilitation is undertaken to recover these benefits in response to widespread wetland degradation. Increasingly, there have been calls to value the benefits of wetland rehabilitation to justify further investment. Such is the case in South Africa. Furthermore, recent global agendas and targets for ecosystem restoration, such as the declaration of the Decade of Restoration 2021-2030, suggest increasing pressure on governments to implement rehabilitation and imply a concomitant increase in decision-making regarding where and how to rehabilitate. In response to these information needs, this thesis explores the economic valuation of wetland rehabilitation through a narrative review of the foundational theory of values and valuation, a quantitative review of applied wetland rehabilitation economic valuation studies, and the evaluation of five wetland rehabilitation projects from South Africa. Projects were selected as case studies to represent various rehabilitation goals and explore different contexts (urban-rural; beneficiary groups), the timing of the evaluation (ex ante, ex post) and value types and valuation methods. The final chapter of the thesis integrates the case study experiences with the findings of the theoretical research components to propose a framework for the valuation of wetland rehabilitation, which can be applied in South Africa, and more generally, to further demonstrate the values of wetland rehabilitation, and as a tool to guide wetland rehabilitation decision-making. While initially grounded in mainstream economics, the research led into a number of fields including philosophy, social-ecological systems and social-ecological relations thinking, several environmental science areas and livelihood and human well-being frameworks. A deeper look into economic theory and history revealed an evolution of thinking on the meaning of ‘value’ and view of ‘nature’ and numerous critiques of standard neoclassical economics. From the insights gained and the case study experiences, this thesis argues that the neoclassical economic perspective, especially combined with a monetary metric, is too restrictive, and arguably too abstract in its assumptions of human behaviour and reliance on mathematical models, as an overarching framework for the valuation of wetland rehabilition. This is not to suggest that standard economic valuation concepts and methods cannot be useful, as the research case studies illustrated, but rather that wetland valuation must be approached from a value pluralism perspective. To this end, the proposed framework offers a way to think beyond, or in addition to, standard economic approaches in articulating the values of wetland rehabilitation. , Thesis (PhD) -- Faculty of Commerce, Economics and Economic History, 2022
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Date Issued: 2022-04-06

Institutional self-deception

Authors: Jacot-Guillarmod, Genevieve Nicole
Date: 2022-04-07
Subjects: Self-deception , Business ethics , Social responsibility of business , Responsibility , Collective behavior Moral and ethical aspects , Attribution (Social psychology)
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294548 , vital:57231 , DOI https://doi.org/10.21504/10962/294548
Description: There are many examples of institutions which have made false claims, or performed certain acts, that have had, to varying degrees, a negative impact on their societies. For example, many corporations go to great lengths to present themselves as being environmentally friendly when in fact they are not. Many corporations have also been forced to recall dangerous products which they at one time or another insisted were safe. Research teams have misled participants with regard to what they can expect from their participation in studies, with grave consequences. Governments throughout the world are mired in corruption, and yet deny that this is so. One possible explanation is that in such situations these institutions are simply lying. However, another possible explanation is that these institutions are self-deceived, or lying to themselves. Recently it has been suggested that self-deception is something that affects certain groups as well as individuals. Given that institutions can wield a great deal of political, social and economic power, if institutions are capable of self-deception there is room for things to go awry on a very large scale with potentially dire consequences. Yet the explanations currently on offer for group-level self-deception appear to amount to instances of individual self-deception (either to certain key individual members of those groups being self-deceived, or to all or most members of a group sharing the same self-deceptive belief), and as such I do not regard the explanations currently on offer as satisfactory. I propose that there are certain situations in which we ought to see institutions themselves as self-deceived or lying to themselves. While the terms ‘self-deception’ and ‘lying to oneself’ are often used interchangeably, I differentiate between the two and argue that both institutional self-deception and an institution lying to itself are institution-level phenomena, and do not rely on any individual within the institution being self-deceived or lying to themselves. That this is so is of relevance to our attributions of accountability, and makes changes to institutional structure and procedures the focus of concern when it comes to preventing an institution succumbing to self-deception or lying to itself. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
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Date Issued: 2022-04-07

The fiction of scarcity: conceptualising scarcity in terms of global justice

Authors: Brotherton, Michelle
Date: 2022-04-07
Subjects: Scarcity Philosophy , Distributive justice , Political science Philosophy , Philosophy , Justification (Ethics) , Fallacies (Logic)
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294526 , vital:57229 , DOI https://dx.doi.org/10.21504/10962/294526
Description: This thesis intends to contribute to the discourse on global justice as it pertains to resources, the distribution of resources, and the allocation of resources. The focus is on the concept of scarcity. I examine scarcity for how it is understood, interpreted, and applied in the literature on global justice. This thesis argues that scarcity lacks conceptual clarity in the discourse on global justice and argues that if scarcity is misconstrued, the consequences can be severe. Conceptual clarity is thus necessary to ensure that scarcity is properly referred to in the discourse on global justice so that scarcity is not erroneously used when justifications are sought for material deprivation and consequent human suffering. In the process, I will also examine how scarcity is used as a justification in instances of material deprivation and why this is problematic. Given the lack of conceptual clarity regarding scarcity, I argue that reliance on scarcity as justification may be erroneous. The conflation of absolute scarcity and relative scarcity may amount to a category mistake. This thesis purports to clarify scarcity conceptually in the context of global justice. In doing so, I recommend that a resource-centric approach to resource scarcity is adopted to accurately account for the scarcity status of resources. A resource-centric approach to resource scarcity based on a more nuanced understanding of scarcity avoids the potential category mistake. Such an approach ensures that material deprivation and consequent human suffering are not wrongfully attributed to scarcity. , Thesis (PhD) -- Faculty of Humanities, Philosophy, 2022
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Date Issued: 2022-04-07

Umzi ka Mama Family property transfer practices and the historical significance of title deeds to African female heads of household in Fingo Village: a participatory theatre approach

Authors: Hellemann, Phemelo Cordelia
Date: 2022-04-07
Subjects: Public history South Africa Eastern Cape , Oral history South Africa Eastern Cape , Women Housing South Africa Eastern Cape , Feminism Africa , Apartheid Law and legislation South Africa , Participatory theater South Africa Eastern Cape , Playback theater , Theater and society South Africa Eastern Cape , History Citizen participation , South Africa. Group Areas Act, 1950
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294537 , vital:57230 , DOI https://doi.org/10.21504/10962/294537
Description: Many everyday stories and experiences of African women remain underrepresented and undocumented. For example, the omission of Fingo Village women’s names from official deeds records silenced their voices. African women faced gender and racial discrimination that denied them fundamental human rights and limited their participation in urban life. Title deed records constitute one type of public record where African women’s names were omitted for centuries by the colonial and apartheid governments. Under apartheid, African women occupied the social status of minors; hence, the government denied them urban land rights. This African feminist study enlists narratives of a sample of seven African female heads of households residing in Fingo Village who are also property owners. Fingo Village is an atypical environment where African people had a rare legal advantage of owning title deeds dating back to 1855. This study employed an interdisciplinary approach by mixing oral history methodology and applied theatre methods to record, interpret and present Fingo Village women’s narratives of family property inheritance and the significance of title deed documentation in the suburb. The multiple technique approach created opportunities for authentic dialogue between the researcher and the participants beyond the inherent limitations of public history oral interviews. The traditional oral history interview and the participatory theatre methods helped uncover unconventional practices in family property relations. Though customary transfers of family homes to custodians were prevalent, title deed registration of family property was also acknowledged as a vital practice that empowered women legally. The researcher used participatory theatre techniques inspired by playback, image and forum theatre to enhance the researcher and participants’ relationship. These methods encouraged the researcher and respondents’ shared authority as they embarked on an extended participatory research project. In this regard, through dialogical and performance-based activities, the participants and the researcher became co-creators of untold Fingo Village stories. Moreover, the theatre techniques became interpretation and analysis tools that ensured that the participants’ untold stories were well represented. The first phase of the research involved engaging with the literature about the title deeds history of Fingo Village and conducting oral history interviews that served as data. In the second phase, the interviews were analysed and packaged in a documentary format. The third phase was a playback theatre inspired session in a 10-minute performance based on themes from the participants’ filmed interviews. Additionally, the performance was a catalyst for forum theatre activities that allowed the participants to interact with the performer and suggest solutions to the dilemma posed by the performer regarding family property use. The participants were decision-makers and family property relations experts within this imagined context. In the fourth phase, the image theatre adaptation and memory work activities were essential tools. The tools aided the visuals and information from an existing Fingo Village exhibition as additional resources that prompted dialogue and discussions. The exhibition encouraged participants to share their personal experiences and memories of the Group Areas Act (GAA) era. The findings showed that the GAA era saw many families revert to communal tenure practices as a strategy to evade forced sales; as such, this gave rise to undocumented family property transfers. Additionally, the findings revealed that though customary practices are often patriarchal, there are circumstances favouring women as the preferred family property custodian. These are embedded in the social status of women who are traditional healers, firstborn daughters, and those from families with just daughters. This study contributes to the growing literature that advocates for positive representation of African women’s stories by using active research methodologies that strengthen partnerships and shared authority between the researcher and the public. This methodology could inspire other researchers to explore theatre techniques to create more profound and meaningful engagements with their participants. The links to the video materials accompanying this thesis are provided on the contents page. , Thesis (PhD) -- Faculty of Humanities, History, 2022
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Date Issued: 2022-04-07

Developing taxonomic and trait-based approaches for assessing and predicting macroinvertebrate responses to elevated fine sediments in the Tsitsa River and its tributaries, South Africa

Authors: Ntloko, Pindiwe
Date: 2022-04-08
Subjects: Water quality South Africa Mzimvubu River Watershed , Sedimentation and deposition South Africa Mzimvubu River Watershed , Aquatic invertebrates Effect of sediments on South Africa Mzimvubu River Watershed , Aquatic invertebrates Classification , Environmental monitoring South Africa Mzimvubu River Watershed , Analysis of variance , Multivariate analysis
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294692 , vital:57245 , DOI 10.21504/10962/294692
Description: Sedimentation of freshwater systems is one of the leading causes of water quality deterioration. The Mzimvubu River catchment, which includes the Tsitsa River and its tributaries, in the Eastern Cape is prone to elevated sediment impact due to dispersive soils that are easily erodible. In this study, taxonomy and trait-based approaches were used to assess the responses of macroinvertebrates to fine sediments in the Tsitsa River and its tributaries. Macroinvertebrates and environmental variables were sampled seasonally in winter, spring, summer and autumn of 2016 to 2018 in six selected sites, using the South African Scoring System version 5 as a collecting protocol. The sites were selected to represent a decreasing gradient of sediment influence from the highly impacted Sites 1 (Tsitsa upstream) 2 (Tsitsa downstream), and 3 (Qurana River) to moderately impacted Sites 4 (Millstream upstream) and 5 (Millstream downstream) and the least impacted Sites 6 (Pot River upstream), 7 (Little Pot River) and 8 (Pot River downstream), which were collectively referred to as the control sites. Analysis of basic physico-chemical variables, dissolved oxygen, pH, electrical conductivity, turbidity, total suspended solids, temperature and nutrients were undertaken seasonally over the study period. Sediments grain sizes were also analysed. All collected data were subjected to appropriate statistical tests – univariate and multivariate techniques. A fine-sediment-specific multimetric index was developed to monitor the impact of fine sediments on macroinvertebrate assemblages of the Tsitsa River and its tributaries. A total of 12 traits, resolved into 48 trait attributes, were selected to explore their distribution in relation to a fine-sediment stress gradient, and identify the trait-based signature of fine-sediment impact. A trait-based approach was then developed to classify South African macroinvertebrates into two groups: taxa that are potentially vulnerable to fine-sediment impact and those potentially resilient, based on the combination of traits possessed. Two-way analysis of variance (ANOVA) indicated that electrical conductivity, turbidity, embeddedness and total suspended solids were statistically significantly different between the sites. Apart from Dissolved oxygen, the remaining variables were statistically significantly lower at the control sites (P < 0.05). The two-way multivariate analysis of variance (MANOVA) indicated global significant differences between sites and seasons. The two-way MANOVA also revealed that the interaction between the sites and seasons were statistically significant. The MANOVA indicated global combined interactive effects across the sites for suspended fine-sediment grain sizes, two-way ANOVA, followed by a Tukey’s post-hoc test, was carried out to indicate where the significant differences lay. The one-way ANOVA results indicated that very fine sand, very coarse silt, medium silt, and fine silt were significantly higher at Tsitsa upstream, Tsitsa downstream, Qurana tributary that is at Millstream upstream, Millstream downstream and Control sites. The rest of the grain sizes did not differ statistically between the sites. In terms of the settled sediment grain sizes, the volumetric analysis did not show considerable differences across the sites. Settled fine-sediment grain sizes were evenly distributed across the sites. Statistically, MANOVA results indicated no significant differences across sites or across seasons. The developed Sediment Multimetric Index indicated that the sites in the Tsitsa River and those in the Qurana River were highly sedimented during the wet season, but became moderately sedimented during the dry season, indicating that the index responded to seasonality. The sediment multimetric index indicated that the control sites were less sedimented during both the wet season and dry seasons, suggesting minimal seasonal effects at the control sites. Traits such as an exposed and soft body, collector-filterers, shredding, feeding on coarse particulate organic matter and a high sensitivity to dissolved oxygen were identified as fine- sediment-sensitive indicator traits. Identified fine-sediment-tolerant traits and ecological preferences included complete sclerotisation, a cased/tubed body, a preference for fine particulate organic matter, a high tolerance to dissolved oxygen depletion, and climbing and skating behaviours. Regarding the trait-based approach followed for classifying macroinvertebrates into vulnerable taxa and resilient taxa, the results revealed that the relative abundance and richness of the vulnerable taxa decreased predictably along the increasing gradient of sediment impact. However, the relative abundance and richness of resilient taxa showed no marked response to the impact of an increasing gradient of fine sediments. Overall, the present study makes a contribution to the complementary application of trait-and taxonomy-based approaches to freshwater biomonitoring. The trait-based approach enables predictions to be made and tested based on the mechanistic understanding of the mediating roles of traits in organism- environment interaction. A fundamental challenge, which showcases the limitation of the current study, is the sparse trait data on Afrotropical macroinvertebrates at the species or generic levels. In this regard, the iv trait-based approaches developed here were the family level instead of species or genus. This is the first study in South Africa to develop explicit trait-based indicators of elevated fine sediments as well as an approach for predicting macroinvertebrate vulnerability and resilience to fine-sediment effects, thus advancing the science and practice of freshwater biomonitoring. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2022
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Date Issued: 2022-04-08

Dynamics of charge movement in ∞-Al2O3:C,Mg using thermoluminescence phototransferred and optically stimulated luminescence

Authors: Lontsi Sob, Aaron Joel
Date: 2022-04-08
Subjects: Thermoluminescence , Optically stimulated luminescence , Phototransfer‎ , Deep traps‎ , Phototransferred thermoluminescence (PTTL)‎
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294607 , vital:57237 , DOI 10.21504/10962/294607
Description: The dosimetric features of ∞-Al2O3:C,Mg have been investigated for unannealed and annealed samples. The unannealed sample is referred to as sample A whereas the samples annealed at 700, 900 and 1200°C for 15 minutes each are referred to as samples B, C and D respectively. A glow curve of unannealed ∞-Al2O3:C,Mg measured at 1°C/s after irradiation to 2.0 Gy consists of peaks at 43, 73, 164, 195, 246, 284, 336 and 374°C respectively. For sample B (annealed at 700°C), a glow curve measured at 1°C/s after irradiation to 3.0 Gy has peaks at 46, 76, 100, 170, 199, 290, 330 and 375°C whereas the glow curve of sample C (annealed at 900°C) recorded under the same conditions consists of peaks at 49, 80, 100, 174, 206, 235, 290, 335 and 375°C respectively. Sample D (annealed at 1200°C) is the most sensitive of the four samples. A glow curve of sample D measured at 1°C/s after irradiation to 0.2 Gy has peaks at 52, 82, 102, 174, 234, 288 and 384°C respectively. The peaks are labelled I-VIII in order of appearance. The 100°C peak, labelled IIa, is induced by annealing at or above 700°C. The dose response of these peaks was studied for doses within 0.1-8.2 Gy. The reported peaks follow first-order kinetics irrespective of annealing temperature. Peaks I-III of each sample are reproduced under phototransfer for preheating up to 400°C. For the unannealed sample, the reproduced peaks are labelled A1-A3 whereas for the annealed samples, they are labelled B1-B3, C1-C3 and D1-D3 respectively. The annealing-induced peak at 100°C is reproduced as B2a, C2a and D2a for samples B, C and D respectively. A PTTL peak labelled C2b or D2b is also observed near 140°C in samples C and D. In addition to these PTTL peaks, a PTTL peak corresponding to peak IV is also found for sample D and for the unannealed sample. As the corresponding conventional peaks, the PTTL peaks of each sample follow first-order kinetics. Peak I and its corresponding PTTL peak for each sample are unstable and fade to a minimal level after 300 s of storage time. On the other hand, peak II of each sample and its corresponding PTTL peak could still be observed with delay up to 5000 s. Peak III of the unannealed sample remains stable with storage time up to 48 hours. Irrespective of annealing, the trap corresponding to peak III is the most sensitive to optical stimulation. Time-dependent profiles of PTTL from unannealed and annealed ∞-Al2O3:C,Mg were also studied. The mathematical analysis of the PTTL time-response profiles is based on experimental results. The role of various electron traps in PTTL was determined by using pulse annealing and by monitoring the dependence of peak intensity on duration of illumination for peaks not removed by preheating. The presence and role of deep traps were further demonstrated with thermally assisted optically stimulated luminescence. For the unannealed sample, the activation energy for thermal assistance is 0.033 ± 0.001 eV and the activation energy for thermal i quenching is 1.043 ± 0.001 eV. For sample C, the activation energy for thermal assistance is 0.044 ± 0.003 eV whereas that for thermal quenching is 1.110 ± 0.006 eV. The values for the activation energy for thermal assistance are lower than those reported in literature. Only the values for the activation energy for thermal quenching are somewhat comparable to values reported elsewhere. , Thesis (PhD) -- Faculty of Science, Physics and Electronics, 2022
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Date Issued: 2022-04-08

Inhibition of aluminium corrosion using phthalocyanines: Experimental and computational studies

Authors: Nnaji, Nnaemeka Joshua
Date: 2022-04-08
Subjects: Aluminum Corrosion , Electrochemistry , Phthalocyanines , Corrosion and anti-corrosives , Protective coatings , Density functionals
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294643 , vital:57240 , DOI 10.21504/10962/294643
Description: Metal deterioration over time is a process known as corrosion, an electrochemical process, which can occur by surface chemical actions on metals by its environment. Metal corrosion have great economic, security, and environmental consequences, and its control is a major research area in corrosion science. Amongst the different corrosion protecting approaches, the use of corrosion inhibitors and protective coatings have attracted enormous research interest in this area of scholasticism. This has necessitated the computational and electrochemical investigations of aluminium corrosion inhibitive potentials of some compounds in 1M HCl. Metal free (5_H2), ClGa(III) (5_Ga) and Co(II) (5_Co) tetrakis(4-acetamidophenoxy)phthalocyanines as well as Co(II) 2,9,16-tris(4-(tert-butyl)phenoxy)-23-(pyridin-4-yloxy)phthalocyanine (6) and Co(II) 2,9,16,24-tetrakis(4-(tert-butyl)phenoxy)phthalocyanine (7) were synthesized for the first time and studied for corrosion inhibition. The reported ClGa(III) tetrakis(benzo[d]thiazol-2-yl-thio)phthalocyaninine (1), ClGa(III) tetrakis(benzo[d]thiazol-2ylphenoxy)phthalocyanine (2), ClGa(III) tetrakis-4-(hexadecane-1,2-dioxyl)-bis(phthalocyanine) (3) and ClGa(III) tetrakis-4,4′-((4-(benzo[d]thiazol-2-yl)-1,2-bis(phenoxy)-bis(phthalocyanine) (4) were also employed for corrosion inhibition of Al in HCl. Corrosion inhibition measurements using electrochemical techniques showed that increased π conjugation caused (1) to (2) to outperform (1a) and (2a) respectively as aluminium corrosion inhibitors in 1.0 M hydrochloric acid. For similar reason, (4) outperformed 2. (1) and (2) were successfully electrodeposited onto aluminium for corrosion retardation in 1.0 M hydrochloric acid solution. Measurements obtained from electrochemical impedance spectroscopy gave corrosion inhibition efficiency values of 82% for 1 and 86% for 2 in 1.0 M hydrochloric acid solution and showed that electrodeposited phthalocyanines have enhanced aluminium corrosion retardation than when in solution. The use of reduced graphene oxide nanosheets (rGONS) alone as aluminium corrosion inhibitor is discouraged because of poor aluminium corrosion inhibition in 1M HCl. However, synergistic effects were observed when rGONS was mixed each with (4) and (3). (5_H2), (5_Ga) and (5_Co) decreased aluminium corrosion in 1M HCl and observation was that the heavier the atom the more decreased the protection and the free base performed best of the three. Studied tertbutylphenoxy-derived CoPcs (6 and 7) exhibited good aluminium corrosion inhibition properties in studied acidic solution and the unsymmetric CoPc (6) which has more heteroatoms, gave better performance. Quantum chemical calculations involved the use of density functional theoretical (DFT) approaches and gave results which corroborated with experimental findings. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
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Date Issued: 2022-04-08

Quantifying the impacts of cactus biological control agents in South Africa

Authors: Mnqeta, Zezethu
Date: 2022-04-08
Subjects: Cactus Biological control South Africa , Noxious weeds South Africa , Invasive plants Biological control South Africa , Insects as biological pest control agents South Africa , Cochineal insect South Africa , Mealybugs South Africa , Agricultural productivity South Africa
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294631 , vital:57239 , DOI 10.21504/10962/294631
Description: Invasive alien cacti are prominent weeds that threaten indigenous biodiversity and have a negative impact on agricultural productivity in South Africa. These plants are problematic because they form dense thickets that reduce the carrying capacity of rangelands; restrict the movement of livestock and wildlife thus reducing access to shade and water sources; and are directly harmful to livestock, wildlife and people due to their sharp spines. Biological control is the most effective, affordable and environmentally friendly method to control invasive alien cacti and minimize their negative impacts. Cochineal insects (Dactylopius spp.: Dactylopiidae) and the gall-forming mealybug, Hypogeococcus sp. (Pseudococcidae) are used as biological control agents for cacti. The agents are however poor dispersers, so mass-rearing and augmentative releases are required in order to establish the agents at sites where they are needed. This study aimed to evaluate the mass-rearing and release efforts of cactus biological control in South Africa, quantify the impact of the biological control agents on cactus plant populations through long-term monitoring, and assess the benefits accrued due to the biological control agents through the perceptions of land-users. An assessment of the effectiveness of the release effort for cactus biological control agents was conducted by comparing where biological control agents have been released with the known distribution of the target weeds. Only 26% of the quarter degree squares that are known to be occupied by invasive alien cacti have had biological control agents released in them. This indicated that the mass-rearing and release efforts in South Africa are inadequate and should be increased, especially in areas where few releases have been made and many cacti are present, such as the Limpopo Province. The impact of the biological control agents on cactus plant populations was assessed by monitoring agent densities, target plant densities and target plant reproductive outputs before and after releases. Plant biomass and reproductive output were reduced by biological control agents for three of the target weeds that were assessed, while the duration of the study was too short to measure reductions for the fourth target weed. Benefits to land-users were then quantified through a questionnaire survey. Land-users perceived biological control as an effective management option, with 81% of the land-users reporting that there was less invasive alien cactus after releasing biological control agents on their land. Forty-nine percent of the land-users believed that the negative impacts of the cactus had been reduced and that they benefited more from their land since control was achieved. Since land-users were only interviewed within four years of the releases being conducted, it is expected that the percentage of land-users who gained benefits from biological control will increase in future. Ninety-seven percent of the land-users stated that the agents were safe and had not fed on any other plants or had any detrimental impacts. These perceptions indicated that land-users regarded biological control as a safe and effective method of controlling invasive alien cacti. This study confirms that biological control is an effective and safe way of controlling invasive alien Cactaceae. It is also the first to assess some of the benefits that land-users have accrued due to biological control of cactus weeds. It is however evident that a greater mass-rearing and release effort is required for South Africa to get the maximum benefits possible from the use of the biological control agents for cactus weeds that are available in the country. , Izityalo ze-cactus ezisuka kwamanye amazwe zilukhula olubalaseleyo, olwenza ingxaki kwintlobo ngeentlobo zezityalo nezilwanyana kwaye ezizityalo zinefuthe neziphumo ezingalunganga kwimveliso yezolimo eMzantsi Afrika. Ezi zizityalo ziyingxaki kuba zenza amatyholo ashinyeneyo athi anciphise umthamo wokusebenzisa umhlaba: zinqanda ukuhamba nogkukhululekileyo kwemfuyo nezilwanyana zasendle ngokwenza oko zingakwazi ukufikelela emthuzini xa kutshisa nakwimithombo yamanzi yokusela; zikwayiyo nengozi kwimfuyo, izilwanyana zasendle kunye nabantu ngenxa yamave abukhali afumaneka kwezizityalo. Ukulawula nokwehliza ubunzini nezinga lemigcipheko yezizityalo, kusetyenziswa indlela ekuthiwa yi-biological control. Lendlela yeyona ndlela isebenza ngokuphucukileyo, efikelelayo, nengenabungozi kokusingqongileyo. Izinambuzane ze- cochineal (i-Dactylopius spp.: Dactylopiidae) kunye ne-mealybug, i-Hypogeococcus sp. (Pseudococcidae) zisetyenziswe njengezixhobo ze-biological control ezinceda ukulawula ezizityalo ze-cactus zingafunekiyo. Ingxaki yazo ezizinambuzane zizixhobo ze-biological control zingentla kukuba azikwazi kuzisasaza ngokwazo ukuba zifikelele nakwizityalo ezikude ngoko ke ukukhuliswa nokukhutshwa ngobuninzi bazo kuyafuneka ukukhawulelana nalengxaki kunye nokwandisa amathuba wokuba zifikelele kuzozonke izityalo ze-cactus ekufuneka zizilawule. Olu phononongo lujolise ekuvavanyeni iinzame zokukhulisa ngobuninzi nokukhupha ezezinambuzane zizixhobo ze-bioloigical control zokulawula izityalo ze-cactus eMzantsi Afrika, ukujonga ubungakanani befuthe notshintsho elenziwa zezinambuzane zizixhobo ze-bioloigical control kwizityalo ze-cactus emva kwexesha elide lokuzijonga, kunye nokuvavanya inzuzo efunyenwe ngenxa yokulawula ezizityalo ze-cactus ngokwemibono yabasebenzisi bomhlaba. Uvavanyo lweenzame zokukhutshwa kwezixhobo zezixhobo zezinambuzane ze-bioloigical control kwizityalo ze-cactus lwenziwa ngokuthelekisa iindawo apho izixhobo zezinambuzane ze-biological control zikhutshwe khona kunye neendawo apho izityalo ze-cactus kwaziwayo ukuba ziyafumaneka khona. Yi-26% kuphela yesikwere sekota eyaziwayo ukuba kukhona izityalo ze-cactus nalapho kukhutshwe khona kwezinambuzane ezizixhobo ze-biological control. Oku kubonisa ukuba iinzame zokukhulisa nokukhutshwa kwezinambuzane ezizixhobo ze-biological control eMzantsi Afrika azanelanga kwaye kufuneka zandiswe, ngakumbi kwiindawo apho kukho ukhutsho olumbalwa olwenziweyo kunye nezityalo ze-cactus ezininzi ezifumaneka khona, njengePhondo laseLimpopo. Iimpembelelo yokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwizityalo ze-cactus zavavanywa ngokujonga ubunizi bezinambuzane ezizixhobo ze-biological control, ukuxinana kwezityalo ze-cactus ekujoliswe kuzo kunye nemveliso yokuzala kwezityalo ze-cactus phambi nasemva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control. Ubungakanani bezityalo ze-cactus kunye nemveliso yokuzala ziye zacutheka emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control kwinzityalo ezintathu ze-cactus ebekujoliswe uvavanyo kuzo, ngelixa ixesha lophononongo lalifutshane kakhulu ukuvavanya unciphiso kwisityalo se-cactus sesine. Izibonelelo zabasebenzisi bomhlaba zaye zavavanywa kusetyenziswa uhlobo lwemibuzo. Abasebenzisi bomhlaba balubona ukusetyenziswa kwezinambuzane ezizixhobo ze-biological control njengendlela yolawulo olusebenzayo, yi81% yabasebenzisi bomhlaba echaze ukuba izityalo ze-cactus zecuthekile emva kokukhutshwa kwezinambuzane ezizixhobo ze-biological control emhlabeni wabo. Amashumi amane anesithoba eepesenti zabasebenzisi bomhlaba bakholelwa ukuba impembelelo ezingalunganga ze-cactus zincitshisiwe kwaye baxhamle kakhulu kumhlaba wabo okoko lwaphunyenzwa. Oludliwano-ndlebe belwenziwe kubasebenzisi bomhlaba kwisithuba seminyaka emine emva kokuba kukhutshwe izinambuzane ezizixhobo ze-biological control, kulindeleke ukuba ipesenti yabasebenzisi bomhlaba abathe bafumana izibonelelo kwi-biological control lonyuke kwixesha elizayo. Amashumi alithoba anesixhenxe ekhulwini abasebenzisi bomhlaba bachaze ukuba izinambuzane ezizixhobo ze-biological control zikhuselekile kwaye khange zidle kuzo naziphi na ezinye izityalo ezingezi eze-cactus ebekujoliswe kuzo okanye zineempembelelo eyingozi. Ezi mbono ziyabonisa ukuba abasebenzi bomhlaba bayithatha i-biological control njengendlela ekhuselekileyo nesebenzayo yokulawula izityalo ze-cactus zamanye amazwe. Olu phononongo luqinisekisa ukuba ulawulo olusebenzisa izinambuzane ezizixhobo ze-biological control yindlela esebenzayo nekhuselekileyo yokulawula iCactaceae yamanye amazwe. Ikwangolokuqala ukuvavanya ezinye zezibonelelo ezizuzwe ngabasebenzisi bomhlaba ngenxa ye-biological control yezityalo ze-cactus. Nangona kunjalo kucacile ukuba ukwandisa inzame zokukhulisa nokukhupha ngobuninzi izinambuzane ezizixhobo ze-biological control kuyafuneka ukuze uMzantsi Afrika ufumane izibonelelo eziphakamileyo enokubakho ngokusetyenziswa kwe zinambuzane ezizixhobo ze-biological control zokulawula ukhula lwe-cactus olukhoyo kweli lizwe. , Thesis (PhD) -- Faculty of Science, Zoology and Entomology, 2022
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Date Issued: 2022-04-08

Singlet oxygen and optical limiting applications of BODIPYs and other molecular dyes

Authors: May, Aviwe Khanya
Date: 2022-04-08
Subjects: Dyes and dyeing Chemistry , Phthalocyanines , Photochemotherapy , Active oxygen , Nonlinear optics , Time-dependent density functional theory , Photochemistry
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294618 , vital:57238 , DOI 10.21504/10962/294620
Description: A series of structurally diverse novel and previously synthesized BODIPY core dyes are synthesized and characterized in this thesis. These BODIPYs were synthesized using 2-methylpyrrole, 2-ethylpyrrole, 2,4-dimethylpyrrole and 3-ethyl-2,4-dimethylpyrrole as the starting pyrroles. The combination of different pyrroles with the same aldehyde results in BODIPY core dyes that are structural analogues. These core dyes were used as precursors to synthesise halogenated BODIPYs and novel styrylBODIPY dyes, which were successfully characterized using FT-IR and 1H NMR spectroscopy. The halogenated BODIPY core dyes and the styrylBODIPY dyes were also characterized using MALDI-TOF mass spectrometry. The introduction of heavy atoms on the BODIPY core leads to a red shift of the main spectral. In the presence of styryl groups, the main spectral band red shifts to the far red end of the visible region. As expected, the halogenated BODIPY core dyes also had moderate singlet oxygen quantum yields. These halogenated core dyes were found to be suitable as photosensitizers as all the dyes reduced bacterial viability to below 50% during photodynamic antimicrobial chemotherapy (PACT) studies against Staphylococcus aureus. The structure-property relationships studied demonstrate that the presence of protons rather than methyls at the 1,7-positions or iodines at the 2,6-positions results in more favorable PACT activity. This is likely to be related to the greater ability of the meso-aryl to rotate into the plane of the dipyrromethene ligand and suggests that there should be a stronger focus on dyes of this type in future studies in this field. During nonlinear optical (NLO) studies, all the styrylBODIPYs exhibited favorable reverse saturable absorption (RSA) responses. In the absence of methyl groups at the 1,7-positions, the meso-aryl ring lies closer to the π-system of the BODIPY core, enhancing donor (D)–π–acceptor (A) properties and resulting in slightly enhanced optical limiting (OL) parameters. Additionally, there is no evidence that the introduction of heavy atoms at the 2,6-positions significantly enhances OL properties. In a similar manner, alkyl substituents at these positions also do not significantly enhance OL properties; this was studied for the first time using 15 with ethyl groups at the 2,6-positions. The combination of z-scan data and transient spectroscopy for 16 demonstrated that the main mechanism responsible for the NLO properties of nonhalogenated BODIPY dyes is one-photon absorption from the ground state followed by ESA in the singlet manifold. From the NLO studies of 25, OL parameters of 1,3,5-tristyrylBODIPY dyes were found to be similar in magnitude to properties of distyrylBODIPY dyes, but to have less favorable optical properties for OL applications. The OL properties of scandium phthalocyanines were assessed for the first time, since the Sc(III) ion, unusually for a first row transition metal ion, is known to readily form sandwich complexes. The presence of a Sc(III) ion does not significantly enhance the OL properties of phthalocyanines relative to those of rare earth metal ions that also form complexes of this type. Because BODIPYs and phthalocyanines typically absorb significantly in the visible region, transparent PBC polymer thin films of disilane-bridged compounds with minimal absorption in this region were studied and exhibited an excellent RSA response. These compounds may be useful in the design of OL materials that can protect the human eye. The optimized geometries and spectroscopic properties of selected BODIPYs were studied. As expected, the presence of bromine, iodine, ethyl and styryl groups at different positions of the BODIPY core leads to a narrowing of the HOMO–LUMO band gap, which results in a red-shift of the main spectral band. Partial atomic charges have also been calculated for some of the styrylBODIPY dyes studied for application in OL, and electrostatic potential energy maps were also visualized to better assess how the dipole moment of BODIPY dyes can be modulated since this can affect the OL properties. For all the BODIPYs studied, the electronegativity of the atoms present influences charge distribution on the BODIPY structure. , Thesis (PhD) -- Faculty of Science, Chemistry, 2022
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Date Issued: 2022-04-08

Synthesis and evaluation of the medicinal potential of novel 4-hydroxycoumarin derivatives

Authors: Manyeruke, Meloddy Hlatini
Date: 2022-04-08
Subjects: Uncatalogued
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/164458 , vital:41120 , doi:10.21504/10962/164458
Description: This research has focused on the synthesis and biological evaluation of a broad range of compounds characterised by the presence of the pharmacologically significant 4-hydroxycoumalin scaffold. The compounds were designed to contain additional pharmachophoric centres to enhance bioactivity and generate lead compounds with dualaction potential. The use of 4-hydroxycoumarin as the primary synthon enabled access to various series of 4-hydroxycoumarin conjugates, the reactive 3-position on the 4-hydroxycoumarin moiety being exploited for regioselective construction of the targeted compounds in several steps. Some of the reactants required in the construction of these compounds were specially synthesised and included propargyloxy benzaldehydes, benzyloxy benzaldehydes and 2,3-dihydroxysuccino-dihydride. Overall, eight different families of novel compounds were accessed, comprising conjugates of 4-hydroxycoumarin with bisethylidenesuccinohyrazide, trifluoroacetamide, amino, benzyloxyphenyl-iminoethyl, benzylidenehyrazinyl-thiazoyl, benzylidenehydrazonoethyl, propargyloxybenzylidenehydrazonoethyl and phenylacryloyl moieties using protocols that required minimal work-up and purification. The eighty novel compounds synthesised in the study were fully characterised using HMRS and advanced NMR techniques. Cytotoxicity, HIV-1 IN and PR inhibitory, and antitrypanosomal, antimalarial and anti-Mtb assays were conducted on the synthesised coumarin derivatives. Several compounds exhibited activity against HIV-1 IN, the most potent being a bis-ethylidenesuccinohyrazide with an IC50 value of 3.5 μM. Various compounds exhibited anti-malarial activity (% pLDH viability in the range 62-77%), anti-trypanosomal activity (the most potent with an IC50 = 0.9 μM against T.b. brucei) and a measure of anti-Mtb activity. Apart from two chalconyl derivatives, none of the synthesised compounds exhibited significant cytotoxicity. Conflicting results were obtained from the in silico docking studies; in some cases supporting the observed in vitro assay data while, in others, exhibiting no correlation. , Thesis (PhD) -- Faculty of Science, Chemistry, 2020
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Date Issued: 2022-04-08

The role of angling-guides in promoting pro-environmental catch-and-release attitudes and behaviours in the recreational angling community

Authors: Farthing, Matthew William
Date: 2022-04-08
Subjects: Fishing , Fishing Catch effort , Fishing guides , Fishers , Human behavior , Role models
Language: English
Type: Academic theses , Doctoral theses , text
Identifier: http://hdl.handle.net/10962/294583 , vital:57235 , DOI 10.21504/10962/294585
Description: Angling-guides are respected as opinion leaders of the recreational angling community, but nothing is known of their influence on angler behaviour. Given their social-standing, angling-guides may be perceived as role-models by angling-clients – thereby promoting the adoption of best and/or poor catch-and-release (C&R) practices, depending on their individual knowledge, attitudes and behaviour. It is critical to understand their potential influence, their knowledge and their behaviours to inform effective intervention strategies which could exploit their extensive networking potential. The aim of this thesis was to better understand the potential utility of angling-guides in efforts to improve angler behaviour. Firstly, this was done by investigating whether angling-guides are perceived as role-models by angling-clients (Chapter 2). Secondly, it was done by assessing the current level of knowledge, attitudes and behaviours of angling-guides from around the world (Chapter 3). Thirdly, it was done by exploring the relationship between angling-guide knowledge, attitudes, intentions and actual behaviour in a case-study of guided-angling trips (Chapter 4). Lastly, it was done by exploring intervention frameworks and incorporating insights into potential strategies for promoting pro-environmental angling behaviours to angling-guides (Chapter 5). To understand if angling-guides are perceived as role-models by the recreational angling community (Chapter 2), a digital survey was designed to assess previous angling-clients’ attitudes towards angling-guides serving the three role-model functions proposed in the Motivational Theory of Role-Modelling, namely as Behavioural models, Representations of the Possible and Inspiration. Of the 492 angling-clients (27 countries), most agreed that angling-guides were competent, skilled, and worth emulating (91.1%), suggesting they are perceived as Behavioural Models. Less agreed that angling-guides were Inspirational or Representations of the Possible (54.8%), suggesting they are less likely to motivate anglers to adopt and/or pursue new goals. As Behavioural Models, angling-guide C&R practices are likely to be emulated, which is of both utility and concern to managers. As angling-guides are likely to be emulated, a digital survey was designed to assess their knowledge, attitudes and behaviours (particularly C&R best-practices) (Chapter 3). Of the 342 angling-guides (47 countries), few had accredited training (9.4%). However, most were deemed “knowledgeable of best-practices” (69.0%), but pervasive misconceptions of key C&R best-practices were observed. Attitudes towards best-practices were generally pro-environmental, and those deemed knowledgeable had significantly more pro-environmental attitudes (p = 0.003). Most angling-guides had pro-environmental attitudes towards their environmental responsibilities (87.1 - 89.5%), but these broad attitudes cannot predict specific pro-environmental behaviours during guided-angling trips where angler satisfaction is often at odds with best-practice. Angling-client satisfaction has important financial implications for angling-guides, and even those with pro-environmental intentions may struggle to adhere to C&R best-practices with inherent sacrifices for the angling-client’s enjoyment. Observation of behaviour in context is critical for understanding the behaviour to be changed. To explore the relationship between angling-guide knowledge, intentions and actual behaviour (Chapter 4), five angling-guides were observed (and filmed) interacting with groups of angling-clients during their guided-angling trips over a 30 day period. Five angling behaviours of interest were identified, and a survey focussed on these behaviours was disseminated (18 months later) to the five angling-guides previously observed to assess their knowledge, attitudes, reported behaviours and perceptions of the norm. Generally the subjects’ reported behaviours aligned well with their knowledge of best-practice, but their actual behaviour was not well aligned (24.4%). Instead, their actual behaviour aligned better with their perceptions of the norm (80.9%), which was generally a “worse” practice than what they reported. Angling-guides appeared to favour client-satisfaction over pro-environmental behaviour. Gaps between angling-guides’ knowledge of best-practice and their actual behaviour indicate that there may be obscure and complex barriers to pro-environmental angling-guide behaviour. Many barriers are seemingly impossible to overcome, such as economic limitations and financial disincentives. These barriers may limit the efficacy of traditional knowledge-attitude-behaviour (KAB) change interventions. The strong alignment of angling-guide behaviour with social norms, and the strong community orientation of recreational angling suggests that the Community-Based Social Marketing (CBSM) approach may be a more effective framework for interventions that aim to promote pro-environmental catch-and-release behaviours at angling-guide level. The CBSM approach allows interventionists to leverage a larger suite of cognitive biases than KAB approaches, provided that sufficient understanding of the context, barriers and benefits for a given segment of the angling-guide community (likely defined by style-of-participation) are obtained. Furthermore, the success of the CBSM approach will depend on the ability of interventionists to effectively recruit and incentivise disjunct and isolated communities of angling-guides to participate in training and workshops in order to achieve the important in-person contact on which the CBSM approach depends. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2022
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Date Issued: 2022-04-08

Showing items 1 - 20 of 283

Analysis of the role of Hsp90 in colon cancer and cancer stem-like cell biology in vitro using a genetically paired cell line model

Systematics and phylogeography of mormyrid fishes in South Africa

Exploring pre-service teachers’ reflective practice in the context of video-based lesson analysis

Maternal health care services in waiting mothers’ shelters: the case of Mawadza village in Bonda, Manicaland, Zimbabwe

Land use decision-making on residential plots in Fingo Village, Makhanda (Grahamstown), South Africa

Constraints and enablements on quality improvement in higher education

Culture, gender and forests: social differentiation in coping and adapting to climate change and other stressors in the south west and east regions of Cameroon

Integrative systematic structuring of the widespread psammophiid snakes (Psammophiidae): a multi-evidence species delineation approach

A wideband spectropolarimetry study of the spatially resolved radio galaxies: Cygnus A & Hydra A

A framework for the economic valuation of wetland rehabilitation: case studies from South Africa

Institutional self-deception

The fiction of scarcity: conceptualising scarcity in terms of global justice

Umzi ka Mama Family property transfer practices and the historical significance of title deeds to African female heads of household in Fingo Village: a participatory theatre approach

Developing taxonomic and trait-based approaches for assessing and predicting macroinvertebrate responses to elevated fine sediments in the Tsitsa River and its tributaries, South Africa

Dynamics of charge movement in ∞-Al2O3:C,Mg using thermoluminescence phototransferred and optically stimulated luminescence

Inhibition of aluminium corrosion using phthalocyanines: Experimental and computational studies

Quantifying the impacts of cactus biological control agents in South Africa

Singlet oxygen and optical limiting applications of BODIPYs and other molecular dyes

Synthesis and evaluation of the medicinal potential of novel 4-hydroxycoumarin derivatives

The role of angling-guides in promoting pro-environmental catch-and-release attitudes and behaviours in the recreational angling community