Towards development of a malaria diagnostic: Generation, screening and validation of novel aptamers recognising Plasmodium falciparum lactate dehydrogenase
- Authors: Frith, Kelly-Anne
- Date: 2020
- Subjects: Plasmodium falciparum , Malaria -- Chemotherapy , Oligonucleotides , Lactate dehydrogenase , Biochemical markers , Systematic evolution of ligands through exponential enrichment (SELEX)
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/142247 , vital:38062
- Description: Malaria, caused by infection with the Plasmodium parasite, is one of the leading causes of death in under-developed countries. Early detection is crucial for the effective treatment of malaria, particularly in cases where infection is due to Plasmodium falciparum. There is, therefore, an enduring need for portable, sensitive, reliable, accurate, durable, self-validating and cost-effective techniques for the rapid detection of malaria. Moreover, there is a demand to distinguish between various infectious species causing malaria. Research in the area of malarial biomarkers has identified a unique, species-specific, epitope of P. falciparum lactate dehydrogenase (PfLDH), enhancing prospects for the development of diagnostics capable of identifying the species causing malarial infection. In recent years, improvements have been made towards the development of rapid diagnostic tests for detecting malarial biomarkers. Owing to their low cost, ease of labeling, and high thermal stability (relative to antibodies), the development and synthesis of aptamers that target the malarial lactate dehydrogenase represents one of the key innovations in the field of rapid diagnostics for malaria. This study explored the generation of aptamers that specifically target P. falciparum. Two sets of aptamers with diagnostically-supportive functions were generated independently, through parallel SELEX of recombinantly-expressed, full-length Plasmodium falciparum lactate dehydrogenase (rPfLDH), and an oligopeptide comprising the P. falciparum-specific epitope on lactate dehydrogenase (LDHp). The latter offers a promising solution for generating aptamers capable of binding with high specificity to P. falciparum. In this work, an rLDH class of aptamers was generated when SELEX was performed using the full-length rPfLDH protein as the target and the LDHp class of aptamers was generated when SELEX was performed using the oligopeptide LDHp as a target. Aptamers were successfully generated through the process of SELEX (systematic evolution of ligands through exponential enrichment) following the study and application of several optimisation steps, particularly during the amplification stage of SELEX. Optimisation steps included the study of improvements in PCR conditions; role of surfactants (Triton-X), modifying the PCR clean-up protocol; and agarose gel excision. Structurally-relevant moieties with particular consensus sequences (GGTAG and GGCG) were found in aptamers both reported here and previously published, confirming their importance in recognition of the target. Novel moieties particular to this work (ATTAT and poly-A stretches) were identified. Clades of consensus sequences were identified in both the rLDH and LDHp groups of aptamers, where sequences in the rLDH clade did not show preferential binding to rPfLDH while those in the LDHp clade (particularly LDHp 3 and 18) were able to recognise and bind only LDHp. Of the 19 sequences returned from the parallel SELEX procedures for rPfLDH (11 sequences) and LDHp (8 sequences), six rPfLDH and all eight LDHp sequences underwent preliminary screening and those with low responses eliminated. Of the eight LDHp-targeting aptamer sequences, five were preliminarily shown to bind to LDHp, whereas only two rPfLDH-targeting sequences were shown to bind to the target (rLDH 4 and 7). To this small selection of rPfLDH oligonucleotide sequences, two more (rLDH 1 and 15) were chosen for further study based on their sequences, secondary and predicted tertiary conformations. Sequences chosen for further study were therefore: rLDH 1, 4, 7 and 15 in the rLDH class, and LDHp 1, 3, 11, 14 and 18 in the LDHp class. Binding properties of the aptamers towards their targets were investigated using enzyme-linked oligonucleotide assays (ELONA), fluorophore-linked oligonucleotide assays (FLONA), electromobility shift assays (EMSA), surface plasmon resonance (SPR), and GelRed dissociation assays, while applications towards aptasensors were explored using electrochemical impedance spectroscopy (EIS) and fluorescent microscopy. Some inconsistencies were seen for specific aptamer to target binding interactions using specific techniques; however, generally, binding to the targets was observed across the techniques assessed. These varied responses demonstrate the need to screen and validate aptamers using a variety of techniques and platforms not necessarily specific for the proposed application. From the aptamer binding screening studies using ELONA, the most promising aptamers generated were identified as LDHp 11, rLDH 4, rLDH 7 and rLDH 15. Aptamer rLDH 4, which was generated against rPfLDH, exhibited preferential and specific binding to the lactate dehydrogenase from P. falciparum, over the recombinantly-expressed lactate dehydrogenase from Plasmodium vivax (rPvLDH), albeit with lowered responses compared to LDHp 11 in ELONA and EMSA studies. However, in kinetic ELONA studies rLDH 4 showed binding to both rPfLDH and rPvLDH. Aptamer rLDH 7 showed high affinity for rPfLDH and rPvLDH in kinetic studies using ELONA. However, screening studies with ELONA indicates that aptamer rLDH 7 may not be suitable for diagnostic tests in serum samples given its non-specific binding to human serum albumin (HSA). Aptamer rLDH 15 exhibited species specificity for rPfLDH in screening studies using ELONA but showed affinity towards rPvLDH (albeit lower relative to its affinity for rPfLDH) in kinetic studies using ELONA. LDHp 11, generated against the PfLDH peptide, showed a clear preference for rPfLDH when compared to rPvLDH and other control proteins, in both sets of ELONA studies conducted, as well as EMSA, thus possessing a strong ability to identify the presence of Plasmodium falciparum owing to its generation against the species-specific epitope. While LDHp 1 demonstrated binding to plasmodial LDH in a flow-through system (SPR), so reiterating ELONA responses, it did not perform well in the remaining methodologies. Aptamers rLDH 1 and 15 and LDHp 3, 14 and 18 exhibited a mixed set of results throughout the target protein screening analyses and were, thus, not considered for selective binding in P. falciparum parasite bodies. In studies aimed at exploring biosensor assemblies utilising the developed aptamers, both rLDH 4 and LDHp 11, along with rLDH 7, LDHp 1 and pL1, demonstrated in situ binding to the native PfLDH in fluorescent microscopy. LDHp 11 exhibited FITC-based fluorescence equivalent to the anti-rPfLDHp IgY antibody in confocal fluorescent microscopy indicating superior binding to the native PfLDH compared to the remaining aptamers. An examination of electrochemical impedance as a platform for a biosensor assembly did not, in these studies, exhibit the required sensitivity using physiologically relevant concentrations of analyte expected for pLDH following infection with Plasmodium spp. Malstat/LDH activity was explored for application in a colorimetric aptasensor. A decrease in both rPfLDH and rPvLDH activity was observed following incubation with the tested aptamers, but rLDH 1, rLDH 7 and LDHp 14 did not exhibit similar decreases in rPvLDH activity. Aptamers rLDH 1, 4 and 7 and LDHp 11 and 14 were, therefore, not selected as candidates for LDH capture in LDH activity-based diagnostic devices for P. falciparum. The decreases in pLDH activity in the presence of aptamers could hold promise as direct or antagonistic malaria therapeutic agents. Preliminary studies on the application of aptamers as malaria therapeutic agents, while of interest, should be viewed with due caution given the challenges of aptamers reaching the intracellular native plasmodial LDH hosted within the red blood cells. In conclusion, this work has shown the ability of the LDHp 11 aptamer, generated in these studies, to selectively bind rPfLDH over rPvLDH, and to bind to the native PfLDH in fluorescent microscopy, indicating that this aptamer holds promise as a biorecognition element in malaria biosensors and other diagnostic devices for the detection, and differentiation, of P. falciparum and P. vivax. The use of a species-specific epitope of P. falciparum as a target in aptamer generation paves the way for similar such studies aimed at generating aptamers with species selectivity for other Plasmodium species.
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Transformative ICT education practices in rural secondary schools for developmental needs and realities: the Eastern Cape Province, South Africa
- Authors: Simuja, Clement
- Date: 2020
- Subjects: Education, Secondary -- South Africa -- Data processing , Information technology -- Study and teaching (Secondary) --South Africa , Educational technology -- Developing countries , Rural development -- Developing countries , Computer-assisted instruction -- South Africa -- Eastern Cape , Internet in education -- South Africa , Rural schools -- South Africa -- Eastern Cape , Community and school -- South Africa -- Eastern Cape
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/150631 , vital:38991
- Description: The perceived social development significance of Information and Communication Technology (ICT) has dramatically expanded the domains in which this cluster of ICTs is being discussed and acted upon. The action to promote community development in rural areas in South Africa has made its way into the introduction of ICT education in secondary schools. Since rural secondary schools form part of the framework for rural communities, they are being challenged to provide ICT education that makes a difference in learners’ lives. This requires engaging education practices that inspire learners to construct knowledge of ICT that does not only respond to examination purposes but rather, to the needs and development aspirations of the community. This research examines the experience of engaging learners and communities in socially informed ICT education in rural secondary schools. Specifically, it seeks to develop a critique of current practices involved in ICT education in rural secondary schools, and explores plausible alternatives to such practices that would make ICT education more transformative and structured towards the developmental concerns of communities. The main empirical focus for the research was five rural secondary schools in the Eastern Cape Province in South Africa. The research involved 53 participants that participated in a socially informed ICT training process. The training was designed to inspire participants to share their self-defined ICT education and ICT knowledge experiences. Critical Action Learning and Philosophical Inquiry provided the methodological framework, whilst the theoretical framework draws on Foucault’s philosophical ideas on power-knowledge relations. Through this theoretical analysis, the research examines the dynamic interplay of practices in ICT education with the values, ideals, and knowledge that form the core-life experiences of learners and rural communities. The research findings of this study indicate that current ICT education practices in rural secondary schools are endowed with ideologies that are affecting learners’ identity, social experiences, power, and ownership of the reflective meaning of using ICTs in community development. The contribution of this thesis lies in demonstrating ways that reframe ICT education transformatively, and more specifically its practices in the light of the way power, identity, ownership and social experience construct and offer learners a transformative view of self and the world. This could enable ICT education to fulfil the potential of contributing to social development in rural communities. The thesis culminates by presenting a theoretical framework that articulates the structural and authoritative components of ICT education practices – these relate to learners’ conscious understandings and represented thoughts, sensations and meanings embedded in the context, and actions and locations of using their knowledge of ICT.
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Understanding a West African recreational fishery as a complex social-ecological system – a case study of the fishery for giant African threadfin Polydactylus quadrifilis (Cuvier, 1829) in the Kwanza Estuary, Angola
- Authors: Butler, Edward C
- Date: 2020
- Subjects: Cuanza River (Angola) , Fishing -- Angola , Polynemidae , Fishes -- Angola -- Ecology
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/146688 , vital:38548
- Description: Despite increasing global recognition of the importance of recreational fisheries, their management largely remains poor. This is because they exhibit unique human-nature relationships and are nested within complex social-ecological systems (SESs). Recreational fisheries in the developing world have large potential for socio-economic development, but are generally underappreciated, in terms of their value and their impact, and are poorly governed. This is particularly concerning as they are highly complex and often compete for resources with dependent artisanal and subsistence fisheries. Developing world recreational fishery SESs are not well understood and present an important research gap for improved governance. The general aim of this thesis was to explore the recreational fishery targeting Polydactylus quadrifilis on the Kwanza Estuary, Angola, and provide context for how managers should approach recreational fisheries in the developing world and in Africa. To do this, the recreational fishery SES was explored using a combination of methodologies including those characteristic of traditional fisheries science, and new methods involving biology, sociology, and economics. The thesis contains an introductory chapter, a chapter describing the background, study area and study species, five data chapters and a discussion chapter. Chapter 3 aimed to investigate the reproductive style of P. quadrifilis. Results identified the species as a protandrous hermaphrodite. Evidence to suggest this included degenerating testicular tissue and the presence of early developing ovarian tissues in transitional individuals. Early-stage oocytes were commonly found in the outer area of male regions and residual late-stage spermatids and spermatozoa were found in the luminal space of ovarian regions, suggesting a process of sex change from the outside inwards. Owing to the species’ reliance on large highly fecund females for reproduction, it is likely that P. quadrifilis will be sensitive to fisheries that target larger individuals, such as trophy recreational fisheries and line fisheries within other sectors. Chapter 4 aimed to investigate alternative methods for adequately describing the growth of P. quadrifilis individuals belonging to either one of two distinct hypothetical life-history pathways: pathway I (‘changers’) – initial maturation as a primary male followed by a sex change to female; pathway II (‘non-changers’) – initial maturation as a male fish with no subsequent sex change, using von Bertalanffy Growth Functions (VBGFs). Other specific objectives included determining the size- and age-at-maturity and size- and age-at-sex-change for P. quadrifilis. Otolith aging revealed rapid growth and early maturation (L50 = 399.2 mm FL, A50 = 1.50 years) and sex change occurred over a wide size (790–1125 mm FL) and age (3–8 years) range. There was strong evidence for partial protandry in P. quadrifilis with several extremely old male fish (up to 22 years) observed in the population. When compared to the conventional model produced for the entire population, there were significant differences in the models for the ‘non-changers’ (LRT, p < 0.01) and their parameters L∞ (full model = 130.8, ‘non-changers’ = 113.3, p < 0.01), k (0.32, 0.44, p < 0.01) and t0 (0.23, 0.43, p = 0.03) in the first approach and the models (LRT, p < 0.01) and their L∞ (‘changers’ = 113.7, p < 0.01) values in the second approach. This suggests that utilising conventional modelling techniques may be inappropriate for the stock assessment and management of P. quadrifilis and, potentially, other sequentially hermaphroditic fishery species. Chapter 5 aimed to assess the sensitivity of P. quadrifilis to recreational C&R within the foreign recreational fishery using a rapid assessment approach. To do this, a number of C&R variables including fight time, air exposure, hook placement, hooking injury, total time of the stress event, river depth and angling method were measured and related to two indicators of fish health and survival – the physiological stress indicators blood glucose and blood lactate concentration and reflex action mortality predictors (RAMPs). Air exposure was identified as a major contributor to motor impairment (Cumulative Link Model: p < 0.01) and fight time was an important contributor to motor impairment via its interaction with air exposure (Cumulative Link Model: p = 0.02). Handling practices appear to be particularly important for larger individuals as fish size was positively correlated with air exposure (Pearson’s r coefficient = 0.41, p < 0.01) and fight times (0.88, p < 0.01). The findings suggest that recreational C&R may result in mortalities directly, via C&R, and indirectly, via predation, and several recommendations were made for best practice. Chapter 6 aimed to assess the direct economic contribution of the recreational fishery for Polydactylus quadrifilis on the Kwanza Estuary. Results indicated that the recreational fishery for contributed significantly to the economy of an area that would otherwise likely receive little external input ($282 054 per four-month fishing season). However, high rates of economic leakage from the study area were identified (58.7%–92.9% of locally spent revenue) and were attributed to the sourcing of lodge supplies, services and staff outside of the local area and the repatriation of profit by foreign business owners. Capacity building within the local community is likely required to develop ‘linkages’ between the local community and the recreational fishery. Greater community involvement in the fishery is suggested to incentivise the protection of recreationally important fishery species and their associated ecosystems. Chapter 7 aimed to investigate the resource user groups involved within the SES. Results illustrated that artisanal and domestic recreational anglers are well-established and are characterised by long histories of participation. The artisanal fishery was highly valued as a source of livelihoods for the local community. Artisanal fishers were eager for involvement in the recreational sector, through the chartering of their vessels, due to the attractiveness of extra earnings. Both recreational and artisanal fishers reported recent decreases in P. quadrifilis catch and anticipated further declines. Domestic recreational anglers appeared to be highly consumptive in their use of the fishery and C&R angling was uncommon. User conflict may be problematic for future management as recreational anglers perceived the artisanal gill-net fishery to be a threat towards P. quadrifilis stocks. In conclusion, the open-access nature of the fishery was identified as the most pertinent threat to its sustainability and likely needs to be addressed. Potential solutions involve offering users the opportunity to purchase access rights (e.g. day permits), thus initiating the concept that users must pay for their use of public resources. Management should aim to protect large female fish due to their increased reproductive value and worth as trophy fish. Thus, C&R angling is likely to be an important interaction between users and the resource. However, angler behaviour will need to be manipulated to promote C&R and minimise C&R-related mortalities. Solutions include angler educational drives and interventions and the implementation of competitive C&R-only angling. Foreign recreational fisheries, although touted as potential ecotourism ventures, will only succeed in improving the lives of local people if they fully integrate the community into the operation of the fishery.
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Understanding biotic interactions in invaded pond communities in the Sundays River irrigation network, South Africa
- Authors: Mofu, Lubabalo
- Date: 2020
- Subjects: Mozambique tilapia -- South Africa -- Sundays River (Eastern Cape) , Western mosquitofish -- South Africa -- Sundays River (Eastern Cape) , Gobiidae -- South Africa -- Sundays River (Eastern Cape) , Clupeidae -- South Africa -- Sundays River (Eastern Cape) , Reservoirs -- South Africa -- Sundays River (Eastern Cape) , Zooplankton -- South Africa -- Sundays River (Eastern Cape) , Freshwater ecology -- South Africa -- Sundays River (Eastern Cape) , Biotic communities -- South Africa -- Sundays River (Eastern Cape) , Fishes -- Effect of temperature on -- South Africa -- Sundays River (Eastern Cape) , Stable isotopes , Relative Impact Potential
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167089 , vital:41436
- Description: The Sundays River valley irrigation ponds provide a unique opportunity to investigate biotic interactions within a biological invasions context, as they contain both native and non-native fish species. This study focusses on two native species (Glossogobius callidus and Gilchristella aestuaria) and two non-native species (Oreochromis mossambicus and Gambusia affinis). The ecology of the ponds was driven by physico-chemical variables, mainly temperature, but the interactions between fishes were a complex interplay between temperature, pond community ecology and food web structure. Seasonal changes in temperature and subsequent fluctuations in water levels resulted in changes in zooplankton community. Chlorophyll-a, temperature, G. callidus and G. affinis were the drivers of the seasonal changes in macroinvertebrate composition. Stable isotope analysis identified substantial ontogenetic dietary shifts in all species, corresponding to changes in body size. Stable isotope analysis revealed that the niche space occupied by G. affinis was broad and overlapped with that of the other three focal species. Stable isotope metrics showed that G. affinis and O. mossambicus utilised a wide range of resources compared to G. callidus and G. aestuaria. Stomach content analysis showed that G. callidus, O. mossambicus and G. affinis fed predominantly on benthic resources, while G. aestuaria fed mainly plankton resources. Functional response experiments revealed that G. callidus and G. affinis both displayed Type II functional responses. In single fish trials, G. affinis had significantly higher functional responses than G. callidus. In heterospecific G. callidus-G. affinis combinations the functional response of G. callidus was reduced by the presence of G. affinis, whereas, this combination greatly enhanced G. affinis functional response magnitudes. The functional response of G. callidus, O. mossambicus and G. affinis under two temperature treatments along with fish abundance data was used to determine temporal differences in the ecological impacts of each fish species between seasons. The relative impact potential of O. mossambicus was consistently higher than that of G. callidus and G. affinis. This study demonstrates how seasonal temperature fluctuations affect the relative impact capacities of introduced species. Overall, this thesis showed that high temperature along with life-history traits contributes to the biotic interactions between native and non-native species in novel environments.
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Understanding climate change and rural livelihoods in Zimbabwe: adaptation by communal farmers in Ngundu, Chivi District
- Authors: Nciizah, Elinah
- Date: 2020
- Subjects: Agriculture -- Zimbabwe , Agriculture -- Climatic factors -- Chivi District (Zimbabwe) , Chivi District (Zimbabwe) -- Rural conditions
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/118765 , vital:34666
- Description: Climate change and variability is a global phenomenon which has deeply localised patterns, dynamics and effects. Amongst those people who are particularly vulnerable to climate change effects are small-scale farmers who are dependent in large part on rain-fed agriculture in pursuing their livelihoods. This is true of small-scale farmers in contemporary Zimbabwe and, more specifically, farmers in communal areas. At the same time, at international and national levels, there are attempts currently to minimise the effects of, and to adapt to, climate change. However, adaptation measures also exist at local levels amongst small-scale farmers, such as communal farmers in Zimbabwe. In this context, as its main objective, this thesis examines climate change and small-scale farmer livelihood adaptation to climate change with specific reference to communal farmers in Chivi District in Zimbabwe and, in particular, in Ward 25 which is popularly known as Ngundu. In pursuing this main objective, a number of subsidiary objectives are addressed, including a focus on the established livelihoods of Ngundu farmers, the perceptions and concerns of Ngundu farmers about climate change, the coping and adaptation measures of Ngundu farmers, and the enablements and constraints which affect attempts by Ngundu farmers to adopt such measures. The fieldwork for the thesis involved a diverse array of research methods, such as a questionnaire survey, life-history interviews, key informant interviews, focus group discussions and transect walks. In terms of theoretical framing, the thesis makes use of both middle-level theory (the Sustainable Livelihoods Framework) and macro-theory in the form of the sociological work of Margaret Archer. Combined, these two theories allow for a focus on both structure and agency when seeking to understand livelihood adaptations to climate change by communal farmers in Ngundu. The thesis concludes that there are massive constraints inhibiting adaptation measures by Ngundu farmers, but that this should not distract from the deep, often historically-embedded, concerns of Ngundu farmers about climate change and the multiple ways in which they express agency in and through adaptation and coping activities. It also highlights the need for more specifically sociological investigations of climate change and small-scale farmer adaptation, as well as the need for localised studies which are able to identify and analyse the specificities of adaptation.
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Urbanisation, foraging and household food security in urban South Africa
- Authors: Garekae, Hesekia
- Date: 2020
- Subjects: Food sovereignty -- South Africa , Food security -- South Africa , Urban density -- South Africa , Urban agriculture -- Law and legislation -- South Africa , Sustainable urban development -- South Africa , Urban ecology (Sociology) -- South Africa , Nutrition surveys -- South Africa -- Potchefstroom , Nutrition surveys -- South Africa -- Thabazimbi , Wild plants, Edible -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/167054 , vital:41433
- Description: Over the past several decades, the world’s population has been rapidly urbanising, which has resulted in a marked shift of global population from rural to urban areas. About half of the global population now reside in urban areas and is projected to increase to two-thirds by the year 2050. However, the majority of the future urban population growth is projected to be largely concentrated in Asia and sub-Saharan Africa. Despite the economic prospects normally synonymous with urbanisation, the current speed and scale of urban transformation comes with formidable challenges to contemporary urban society in these two continents. Urbanisation may presents social, economic, health and environmental challenges in urban areas, not least being a shift of the locus of food insecurity from rural to urban areas, leading to poor dietary diversity among many urban dwellers. Similarly, urbanisation alters key ecosystem services and drives habitat alteration and fragmentation, biodiversity loss, proliferation of non-native species and changes on species diversity and richness. The aforementioned changes can result in a deterioration of living conditions and decline on the quality of life for the urban dwellers. However, on the other hand, urban green infrastructure is posed as vital tool in promoting liveable cities and enhancing livelihood resilience. Against this backdrop, this study portrays wild plants, a component of urban green infrastructure, as a key resource in promoting food security and dietary diversity, thereby promoting livelihood resilience and reduced vulnerability, especially of the urban poor. Framed under the ‘right to the city’ approach, this study examined urban foraging practices and their potential contribution to dietary diversity and how they are shaped by and respond to urbanisation in two medium-sized South African towns. The study was conducted in the towns of Potchefstroom and Thabazimbi, South Africa. An explanatory sequential mixed method design was employed for data collection. Multi-stage sampling was employed in selecting the study participants. Firstly, the study towns were stratified into four socio-economic zones: informal, reconstruction and development programme, township and affluent. These zones resemble high density (informal, reconstruction and development programme), medium density (township) and low density (affluent) areas. Then, a total of 374 households were randomly sampled across the socio-economic zones for the main survey (Chapter 3 and 5). A subset of this sample, i.e. 72 participants was considered for dietary recalls, alongside with a random sample of 65 non-foragers (Chapter 4). An inventory of plant species available in a given foraging space was conducted from a total of 136 plots spread across different urban spaces (Chapter 2). Semi-structured interviews were conducted with a total of 81 participants (sub population of the main survey) for elucidating data on urban dynamics (Chapter 6). Lastly, complementary in-depth interviews with 46 participants were conducted. The findings showed that different urban spaces were constituted by diverse vegetation, with 262 distinct plant species encountered across the spaces. The majority (60.7%) were indigenous to South Africa. Species composition and diversity varied with space type, being significantly high in protected areas as compared to the other space types. About half (53%) of the identified plant species had at least one documented use, with medicine, food and firewood being modal, in order of frequency. Species composition and diversity differed between forageable and non-forageable species, being significantly high for forageable species. Urban foraging was widespread, about 68% of the respondents reported foraging. Foraging provided food, fuel energy, medicine, and cultural affirmation, among others. Despite the high prevalence rate of foraging, the study did not find any meaningful contribution of wild foods to overall diets. Nonetheless, wild foods demonstrated a substantial contribution in diversifying diets within particular food groups consumed such as vegetables, thus emerging essential in mitigating monotonous urban diets, particularly of the urban poor. Besides, the prevalence of foraging differed significantly between and within towns, being high for Thabazimbi (54.7%) and residents in the outskirts of town (86.2%) than Potchefstroom (45.3%) and residents in the inner part of town (33.3%). Participation in foraging was primarily a function of childhood (91.8%) exposure and experience with foraging, positive perceptions (79%) towards practice, resident in the outskirts of town (86.2%) and low household income (49.2%). The findings indicated that foraging was driven by multifaceted motivations, with culture (91.8%), health (88.7%), livelihoods needs (75.0%) and leisure (73.8%) being the most common. Vacant spaces (54.7%), riparian areas (30%), and domestic gardens (17.9%) were the most preferred foraging spaces, albeit with differences within towns. Similarly, the mean frequency of access varied with foraging spaces, being slightly high for vacant spaces than riparian areas and domestic gardens. The majority of the respondents were unaware of both formal and informal regulations managing urban landscapes, with those acknowledging some awareness falling short of articulating on the specificities of the regulations. Besides, the findings showed that foraging practice was threatened by urban transformation. Foragers perceived that the practice has changed over time, in terms of spaces, participants and regulations. There was a decreasing trend on the number and size of foraging spaces as well as shifting demographic trends of foragers. Moreover, urban transformation brought about a new set of regulations used for managing certain spaces within the urban landscape. However, some regulations prohibited or restricted access and rights to certain spaces for foraging. Hence, this prompted foragers to devise adaptation strategies to cope with the said changing dynamics. Exploring new foraging sites within and outside forager’s neighbourhoods and negotiating access entry were the most frequently mentioned adaptation strategies. This study contributes to the emerging body of knowledge on urban foraging, which has being seldom understood in the Global South.
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Walking at the intersection of Seamon’s place ballet and Relph’s insideness: understanding how students experience the university as a place through their everyday habitual walking
- Authors: Mtolo, Siyathokoza Monwabisi
- Date: 2020
- Subjects: Seamon, David , Relph, EC , College students -- South Africa -- Makhanda -- Attitudes , Walking -- Sociological aspects , College students -- South Africa -- Makhanda -- Political activity , Rhodes University -- Students -- Attitudes , Student movements -- South Africa -- Makhanda
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/162901 , vital:40995
- Description: Walking as a way to experience a place is a relatively understudied area of phenomenological study. Furthermore, globally (the world) and locally (South Africa) the study of the experience of tertiary education institutions as walked environments is minimal (see Puig-Ribera et al., 2008; Speck et al., 2010; Mtolo, 2017). However, the events of the South African #MustFall moment – especially the #RhodesMustFall part of the moment and how it began with the desecration of a statue that was walked past and found to be a misplaced artefact in a society that is in postcolonial/post-Apartheid times and space – highlighted the pressing need to study the experience of the university as a place through which habitual walking takes the student through moments of movement, rest, and encounter that are a highly consequential way in which placeness is experienced. This study is a way to document how students at Rhodes University experience the university’s placeness quality, through habitual walking, in an example of the way in which a place is experienced through moments of movement, rest, and encounter. For this study in-depth mobile interviews were conducted with 12 student participants from Rhodes University. The interviews were video-recorded as the participants talked while traversing through habitually walked areas of the campus that are the meaning-infused spaces which make up the Rhodes University that they traverse through on a daily basis. The dissertation found that in the experience of Rhodes University, through habitually walking its placeness, people experience moments of movement, rest, and encounter that are highly targeted and personalised. The experience of the Rhodes University campus is an experience of people and the built-up and decorated environment along similar lines. People bring to the experience of their walked space past experiences which inform consequentially how any space that is walked is experienced. People further employ strategies to ensure that the experience of walking a space is more to their desired quality as an experience, which ends up being meaningful and most likely to affect future instances of walking through meaning-infusing and meaning-infused space. Ultimately, the habitual walking of Rhodes University consequentially informs the relationship between students and Rhodes University’s placeness, as the walking is a way of learning how to be within a placeness that is engaged through alternating moments of movement, rest, and encounter that incrementally ‘open’ for experience Rhodes University in such a targeted manner that every student eventually has their personal and customised Rhodes University by virtue of it being just those sites and situations which have been engaged through habitual walking.
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Zimbabwean women online: an investigation of how gendered identities are negotiated in Zimbabwean women’s online spaces
- Authors: Ndlovu, Nonhlanhla
- Date: 2020
- Subjects: Woman -- Zimbabwe -- Social life and customs Social media -- Social aspects -- Zimbabwe Facebook (Firm) Women -- Zimbabwe
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/140452 , vital:37890
- Description: This study is concerned with the construction of Zimbabwean women’s identities in this contemporary internet age. Two Facebook groups are of particular interest here due to the vibrant conversations that take place on a daily basis, that is, Makhox Women’s League and Baking & Cooking: ZW Women’s Diaries. Conceiving these internet sites as discursive spaces, I unpack the contesting discourses and tensions in the different narratives offered by Zimbabwean women and identify and critique the competing sets of feminine subjectivities. I achieve this by drawing on poststructuralist and postcolonialist feminist theories in order to situate these groups as cultural sites that are particularly identity defining. I particularly draw on Foucauldian theories of discourse, power and the subject to conceptualise the formation of particular discursive gendered subjectivities. With an understanding that discourse is constitutive of power relations and contestations, and that discourse should be historically contextualised in order to take into account particular conditions of existence; I draw on Mamdani’s (1996) conceptualisation of how power is organised in Africa within a historical and institutional context, and identify the bifurcated nature of the postcolonial Zimbabwean state as a colonial residue as necessitating a particular kind of subjectivity. To this end, one can understand the different femininities on Makhox Women’s League and Baking & Cooking: ZW Women’s Diaries as constituted within, and complexly negotiating, a traditional/customary discourse and a rights-based modern one. This qualitative inquiry is informed by an eclectic approach that combines methods of textual analysis that complements both critical linguistics and media studies and attends to lexical structure as well as narrative and rhetorical analysis respectively. Combined with an online ethnographic approach I employ these tools to analyse these particular Facebook groups with the understanding that as women converse daily on these platforms, they ‘govern’ each other’s conduct and thought processes in interesting ways. I argue that these conversations discursively constitute the performances of different femininities on both sites that also take into account the diasporic condition of Zimbabwean women. I show how they negotiate and mediate feminine performance and in so doing propose and contest certain ‘truths’ that are frequently validated.
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‘Being regional’: an analysis of the conceptualisation, operations and embeddedness of regional non-governmental organisations responding to HIV and AIDS in Southern Africa
- Authors: Mushonga, Allan
- Date: 2020
- Subjects: AIDS (Disease) -- South Africa -- Finance , Non-governmental organizations -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/118733 , vital:34663
- Description: This thesis offers an original sociological analysis of regional Non-Governmental Organisations (RNGOs) responding to the HIV epidemic in the Southern African Development Community (SADC) in respect of their emergence, constitution, role, function, embeddedness, accountability and practice of being regional in the HIV response. In doing so, it offers propositions on the conceptualisation of RNGOs and the concept being regional in clarifying regional HIV programming in the context of regionalisation. It also highlights the nexus between regional HIV work, and country and global HIV governance and programming as components of the global architecture of development regime under the tutelage of the United Nations as influenced by the dominant powers. The analysis is based on a hybrid of social systems, actor systems dynamics, institutional and network theoretical analytical frameworks. A triangulation of these frameworks provides a comprehensive grounding on which it is possible to identify and analyse RNGOs as social systems, institutions, actors and nodes that constitute part of the global architecture of the HIV response. This also facilitates the conceptualisation of being regional as both a programmatic typology and state of existence of RNGOs, thus locating these regional actors in the framework of the global HIV governance and programming. It locates them in the resultant web of social relations connecting various development agents in hierarchical and institutionalised structures constructed around HIV governance and responses. Social embeddedness and hence accountability of RNGOs is thus presented as determined by this complex context. Based on an extensive use of organisational documents as well as key informant interviews, the thesis reveals the dominance of funding organisations in determining regional and national HIV programme design and content as well as structuring the organisational practices of RNGOs and other development agents in the HIV response. Because of the demands by donors for accountability on the part of RNGOs for funds received, upward accountability becomes a major preoccupation of RNGOs and becomes privileged compared to downward accountability to their programme beneficiaries. However, RNGOs still enact agency in seeking to manoeuvre their way through the worldwide development system in order to advance the HIV response while also ensuring their own organisational sustainability.
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“A position of great trust and responsibility”: a social history of the Grahamstown Asylum, 1875 – c. 1905
- Authors: Van Zyl, Kylie
- Date: 2020
- Subjects: Mental health services -- South Africa -- Cape of Good Hope , Psychiatric hospitals -- South Africa -- History , South Africa -- Race relations -- Social aspects , Mentally ill -- Commitment and detention -- South Africa , Mentally ill -- Abuse of -- South Africa , Mental health policy -- South Africa , Asylums -- South Africa -- Grahamstown , Discrimination in mental health services -- South Africa , Health and race -- South Africa -- History
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/151031 , vital:39025
- Description: Much has been written about the inequalities inherent in the psychiatric care provided to mentally ill individuals in the Cape Colony, but to date few works have been produced that describe in detail the processes and care regimes at particular institutions. This thesis examines the history of care and custody provided by the Grahamstown Asylum in the Cape between the years of 1875 and 1905. The intention is to determine the means and methods by which the Asylum’s authorities developed, almost unchallenged, a system of unequal treatment and favouritism within that facility, and what this meant for the men and women committed to the Asylum’s custody. To this end, contemporaneous official reports from Asylum staff and Colonial authorities were consulted, in conjunction with the Asylum’s internal records such as registers and individual patient files. This thesis concludes that the evolution of the Colony’s psychiatric community’s beliefs around mental illness, philosophies of protective custody and moral treatment within the psychiatric community at the time, the region’s laws governing psychiatric institutionalisation, and the larger context of the Cape’s socio-political environment at the time converged to create an institution that practiced discrimination on both a macro- and micro-level. This discriminatory framework affected who was admitted, the diagnosis that each person received, the asylum facilities to which they had access, and further, to the odds against their recovery. The implications of this study are relevant in the present day, as the modern South African system of psychiatric institutionalisation, though embedded within a socio-political context of equality and non-discrimination nevertheless appears to suffer from a similarly undemocratic framework of operation.
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“Don’t be alarmed. It’s to do with sex.” Sherlock Holmes fanfiction and freedom of the imaginary domain
- Authors: van der Nest, Megan
- Date: 2020
- Subjects: Fan fiction , Fans (Persons) -- Fiction , Holmes, Sherlock , Literature and the internet , Sex in literature
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/124208 , vital:35576
- Description: In this thesis I argue that, for the individual fan, reading and writing fanfiction texts, and engaging with the online fandom communities within which these texts are produced, is a potentially valuable experience. This is because the kind of social and creative spaces found in these communities allow for, and celebrate, the free imaginative play with romantic and sexual desires, identities, and relationships. To articulate the importance of these spaces, I draw on Drucilla Cornell’s concept of the imaginary domain, defined as the psychic space each individual uses to explore different sexual desires and personae, which exploration is necessary for the development of full personhood. I also argue that the growing visibility and influence of fandom in modern society means that it could serve as a mechanism for social change, particularly in the acceptance and support of multiple sexual identities and forms of love. Selected texts, drawn from the Sherlock fandom, are discussed as representative of the approach taken within fanfiction communities towards various aspects of sexuality and sexual ethics. This approach combines the enthusiastic exploration of sexual desires without shame or fear of judgment with an ongoing, critical interrogation of sexual ethics.
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#KeepItReal: discursive constructions of authenticity in South African consumer culture
- Authors: Plüg, Simóne Nikki
- Date: 2019
- Subjects: Consumer behavior Consumers' preferences -- South Africa Brand choice -- South Africa Marketing -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/64973 , vital:28641
- Description: Writers as diverse as Oscar Wilde (1915), Matthew Arnold (1960), Erich Fromm (1997) and a proliferation of contemporary self-help gurus, variously assert that it is preferable for people to focus on “being”, or to value “who you are”, instead of emphasising “having” or the material possessions you have acquired. These discourses assert that individuals content with “being” are happier and more fulfilled than those involved in the constant (and alienating) motion of acquiring material goods as representations of themselves (de Botton, 2004; Fromm, 1997; James, 2007). This thesis provides an in-depth critical exploration of one of these ideal “ways of being”: authenticity. It does not seek to discover what authenticity is in an empirical sense, nor to define what it should be in a normative sense, but to map the cultural work done by changing and often contradictory discourses of personal authenticity. More specifically, this study uses a qualitative research design, social constructionist theoretical framework, and discourse analytic method to critically discuss the discursive constructions of subject authenticity in South African brand culture. The sample consisted of (1.) ten marketing campaigns of several large, mainstream brands, which were popular in South Africa from 2015 to 2017, and (2.) fifteen smaller South African “craft” brands popular in the “artisanal” context. The analysis is presented in two distinct, but interrelated, sections (namely, Selling Stories and Crafting Authenticity), where the relevant discourses of authenticity for each data set are explored in depth. Through this analysis the thesis provides a critical discussion of the ways in which these discourses of authenticity work to produce and maintain, (or challenge and subvert), subject positions, ideologies, and power relations that structure contemporary South African society.
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A critical realist exploration of the culture of resistance in educational technology integration practices at a South African university
- Authors: Tshuma, Nompilo
- Date: 2019
- Subjects: Critical realism , Educational technology -- South Africa , Education, Higher -- Effect of technological innovations on -- South Africa , College teachers -- South Africa , College teaching -- Sociological aspects -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/72318 , vital:30033
- Description: This thesis seeks to address a number of troubling concerns related to research and practice in the field of educational technology in South African higher education. Firstly, educational technology research has been criticised for a lack of theoretical rigour resulting in perspectives that are tightly focused mostly on practice but fail to adequately interrogate the socio-political complexities of integrating educational technology. Secondly, while research in the field has been criticised for failing to adequately contextualise the study of educational technology, it also fails to interrogate the impact of colonial legacies and Western-developed technologies on integration practices. Thirdly, there seems to be a disconnect between academics’ practices and choices with educational technology, and the expectations and assumptions of educational technologists. As such, this thesis predominantly follows inductive reasoning where literature and theory are applied to the empirical situation retrospectively in order to avoid the potential influences and biases of mostly Western-driven discourses on educational technology integration practices. Critical realism is used to ‘underlabour’ this study. This meta-theory asserts that there are multiple perspectives of an independent reality, and the work of research is to use these perspectives to draw closer to an understanding of that reality. As such, it allows me to interrogate my perspectives firstly, and secondly those of my research participants, about factors that constrain educational technology integration in the South African context through the use of theory (abstract concepts) and data (research participants’ multiple perspectives). However, critical realism is somewhat cautious in how to access this reality. Therefore, a critical ethnographic epistemology is employed to strengthen critical realism’s aim of accessing knowledge. A critical epistemology emphasises exposing hidden power structures, value judgements as well as self-knowledge and reflexivity. The thesis thus shows how a critical realist ontology could be complemented by a critical ethnographic methodology, particularly in critically-orientated research that has an emancipatory focus which seeks to uncover the socio-political context within which educational technology practices take place. A key argument is that critical realism can be employed as an ontological underlabourer for critical research because of: 1) its immanent critique of traditionally-accepted philosophies, 2) its emphasis on critique of our knowledge claims and value judgements, 3) its insistence that knowledge of the social world necessarily precedes emancipation, and 4) its different conceptions of power (oppressive power and transformatory power). This critical ethnographic research is conducted in a South African university with eight female academics. Data collection is in the form of interviews, observations and reflections, as well as informal and work-related interactions. At each data collection moment, I have had to be reflexively aware of my positionality as an educational technologist, the impact of a colonially-motivated methodology and an ethically-aware approach that seeks to put the needs of the research participants first. Critical ethnography’s meaning-making and critical realism’s abduction and retroduction are used to analyse and make sense of the data. In my attempt to contextualise the study’s findings, I first uncover structural forces and their impact on the academic role before attempting to correlate this with educational technology practices. The study’s findings point to two main structural forces in the socio-political context of South African higher education: the teaching/research tension and the elevation of one dominant culture. In terms of the teaching/research tension, the female academics in this study have to balance the urgent teaching function with the valued research function. They struggle to find this balance because of ambiguous messages from different structures, their passion for teaching, oppressive departmental dynamics and the pressures of their career trajectory. The elevation of one dominant culture is demonstrated through both oppressive cultural practices and untransformed curricula. The study shows that academics mitigate these structural constraints mostly through subtle every day resistance that seeks to mitigate their effect on both the academics and, where applicable, their students. Archer’s morphogenetic/morphostatic cycle is used retrospectively, in response to fieldwork, to conceptualise why this resistance comes about. A resistance framework developed using Archer is then used to understand educational technology choices and practices. The results of the research show that while academics are often pictured as resistant to technology as a response to different barriers, they actually often employ technology to resist structural forces. That is, with this thesis I show that there is a focus on resistance with technology rather than resistance to technology. The study shows how the research participants resist structural forces (teaching tension and dominant culture) by using technology to create safe and responsive learning spaces. As such, this thesis challenges educational technologists to re-think the way they support academics by recommending support strategies that acknowledge both the structural forces in the South African higher education context, as well as the culture of resistance, both of which impact academics’ educational technology choices and practices.
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A development method for deriving reusable concurrent programs from verified CSP models
- Authors: Dibley, James
- Date: 2019
- Subjects: CSP (Computer program language) , Sequential processing (Computer science) , Go (Computer program language) , CSPIDER (Open source tool)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/72329 , vital:30035
- Description: This work proposes and demonstrates a novel method for software development that applies formal verification techniques to the design and implementation of concurrent programs. This method is supported by a new software tool, CSPIDER, which translates machine-readable Communicating Sequential Processes (CSP) models into encapsulated, reusable components coded in the Go programming language. In relation to existing CSP implementation techniques, this work is only the second to implement a translator and it provides original support for some CSP language constructs and modelling approaches. The method is evaluated through three case studies: a concurrent sorting array, a trialdivision prime number generator, and a component node for the Ricart-Agrawala distributed mutual exclusion algorithm. Each of these case studies presents the formal verification of safety and functional requirements through CSP model-checking, and it is shown that CSPIDER is capable of generating reusable implementations from each model. The Ricart-Agrawala case study demonstrates the application of the method to the design of a protocol component. This method maintains full compatibility with the primary CSP verification tool. Applying the CSPIDER tool requires minimal commitment to an explicitly defined modelling style and a very small set of pre-translation annotations, but all of these measures can be instated prior to verification. The Go code that CSPIDER produces requires no intervention before it may be used as a component within a larger development. The translator provides a traceable, structured implementation of the CSP model, automatically deriving formal parameters and a channel-based client interface from its interpretation of the CSP model. Each case study demonstrates the use of the translated component within a simple test development.
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A dynamics based analysis of allosteric modulation in heat shock proteins
- Authors: Penkler, David Lawrence
- Date: 2019
- Subjects: Heat shock proteins , Molecular chaperones , Allosteric regulation , Homeostasis , Protein kinases , Transcription factors , Adenosine triphosphatase , Cancer -- Chemotherapy , Molecular dynamics , High throughput screening (Drug development)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/115948 , vital:34273
- Description: The 70 kDa and 90 kDa heat shock proteins (Hsp70 and Hsp90) are molecular chaperones that play central roles in maintaining cellular homeostasis in all organisms of life with the exception of archaea. In addition to their general chaperone function in protein quality control, Hsp70 and Hsp90 cooperate in the regulation and activity of some 200 known natively folded protein clients which include protein kinases, transcription factors and receptors, many of which are implicated as key regulators of essential signal transduction pathways. Both chaperones are considered to be large multi-domain proteins that rely on ATPase activity and co-chaperone interactions to regulate their conformational cycles for peptide binding and release. The unique positioning of Hsp90 at the crossroads of several fundamental cellular pathways coupled with its known association with diverse oncogenic peptide clients has brought the molecular chaperone under increasing interest as a potential anti-cancer target that is crucially implicated with all eight hallmarks of the disease. Current orthosteric drug discovery efforts aimed at the inhibition of the ATPase domain of Hsp90 have been limited due to high levels of associated toxicity. In an effort to circumnavigate this, the combined focus of research efforts is shifting toward alternative approaches such as interference with co-chaperone binding and the allosteric inhibition/activation of the molecular chaperone. The overriding aim of this thesis was to demonstrate how the computational technique of Perturbation response scanning (PRS) coupled with all-atom molecular dynamics simulations (MD) and dynamic residue interaction network (DRN) analysis can be used as a viable strategy to efficiently scan and accurately identify allosteric control element capable of modulating the functional dynamics of a protein. In pursuit of this goal, this thesis also contributes to the current understanding of the nucleotide dependent allosteric mechanisms at play in cellular functionality of both Hsp70 and Hsp90. All-atom MD simulations of E. coli DnaK provided evidence of nucleotide driven modulation of conformational dynamics in both the catalytically active and inactive states. PRS analysis employed on these trajectories demonstrated sensitivity toward bound nucleotide and peptide substrate, and provided evidence of a putative allosterically active intermediate state between the ATPase active and inactive conformational states. Simultaneous binding of ATP and peptide substrate was found to allosterically prime the chaperone for interstate conversion regardless of the transition direction. Detailed analysis of these allosterically primed states revealed select residue sites capable of selecting a coordinate shift towards the opposite conformational state. In an effort to validate these results, the predicted allosteric hot spot sites were cross-validated with known experimental works and found to overlap with functional sites implicated in allosteric signal propagation and ATPase activation in Hsp70. This study presented for the first time, the application of PRS as a suitable diagnostic tool for the elucidation and quantification of the allosteric potential of select residues to effect functionally relevant global conformational rearrangements. The PRS methodology described in this study was packaged within the Python programming environment in the MD-TASK software suite for command-line ease of use and made freely available. Homology modelling techniques were used to address the lack of experimental structural data for the human cytosolic isoform of Hsp90 and for the first time provided accurate full-length structural models of human Hsp90α in fully-closed and partially-open conformations. Long-range all-atom MD simulations of these structures revealed nucleotide driven modulation of conformational dynamics in Hsp90. Subsequent DRN and PRS analysis of these MD trajectories allowed for the quantification and elucidation of nucleotide driven allosteric modulation in the molecular chaperone. A detailed PRS analysis revealed allosteric inter-domain coupling between the extreme terminals of the chaperone in response to external force perturbations at either domain. Furthermore PRS also identified several individual residue sites that are capable of selecting conformational rearrangements towards functionally relevant states which may be considered to be putative allosteric target sites for future drug discovery efforts Molecular docking techniques were employed to investigate the modulation of conformational dynamics of human Hsp90α in response to ligand binding interactions at two identified allosteric sites at the C-terminal. High throughput screening of a small library of natural compounds indigenous to South Africa revealed three hit compounds at these sites: Cephalostatin 17, 20(29)-Lupene-3β isoferulate and 3'-Bromorubrolide F. All-atom MD simulations on these protein-ligand complexes coupled with DRN analysis and several advanced trajectory based analysis techniques provided evidence of selective allosteric modulation of Hsp90α conformational dynamics in response to the identity and location of the bound ligands. Ligands bound at the four-helix bundle presented as putative allosteric inhibitors of Hsp90α, driving conformational dynamics in favour of dimer opening and possibly dimer separation. Meanwhile, ligand interactions at an adjacent sub-pocket located near the interface between the middle and C-terminal domains demonstrated allosteric activation of the chaperone, modulating conformational dynamics in favour of the fully-closed catalytically active conformational state. Taken together, the data presented in this thesis contributes to the understanding of allosteric modulation of conformational dynamics in Hsp70 and Hsp90, and provides a suitable platform for future biochemical and drug discovery studies. Furthermore, the molecular docking and computational identification of allosteric compounds with suitable binding affinity for allosteric sites at the CTD of human Hsp90α provide for the first time “proof-of-principle” for the use of PRS in conjunction with MD simulations and DRN analysis as a suitable method for the rapid identification of allosteric sites in proteins that can be probed by small molecule interaction. The data presented in this section could pave the way for future allosteric drug discovery studies for the treatment of Hsp90 associated pathologies.
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A multi-threading software countermeasure to mitigate side channel analysis in the time domain
- Authors: Frieslaar, Ibraheem
- Date: 2019
- Subjects: Computer security , Data encryption (Computer science) , Noise generators (Electronics)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71152 , vital:29790
- Description: This research is the first of its kind to investigate the utilisation of a multi-threading software-based countermeasure to mitigate Side Channel Analysis (SCA) attacks, with a particular focus on the AES-128 cryptographic algorithm. This investigation is novel, as there has not been a software-based countermeasure relying on multi-threading to our knowledge. The research has been tested on the Atmel microcontrollers, as well as a more fully featured system in the form of the popular Raspberry Pi that utilises the ARM7 processor. The main contributions of this research is the introduction of a multi-threading software based countermeasure used to mitigate SCA attacks on both an embedded device and a Raspberry Pi. These threads are comprised of various mathematical operations which are utilised to generate electromagnetic (EM) noise resulting in the obfuscation of the execution of the AES-128 algorithm. A novel EM noise generator known as the FRIES noise generator is implemented to obfuscate data captured in the EM field. FRIES comprises of hiding the execution of AES-128 algorithm within the EM noise generated by the 512 Secure Hash Algorithm (SHA) from the libcrypto++ and OpenSSL libraries. In order to evaluate the proposed countermeasure, a novel attack methodology was developed where the entire secret AES-128 encryption key was recovered from a Raspberry Pi, which has not been achieved before. The FRIES noise generator was pitted against this new attack vector and other known noise generators. The results exhibited that the FRIES noise generator withstood this attack whilst other existing techniques still leaked out secret information. The visual location of the AES-128 encryption algorithm in the EM spectrum and key recovery was prevented. These results demonstrated that the proposed multi-threading software based countermeasure was able to be resistant to existing and new forms of attacks, thus verifying that a multi-threading software based countermeasure can serve to mitigate SCA attacks.
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A physiological study on a commercial reef fish to quantify the relationship between exploitation and climate change resilience
- Authors: Duncan, Murray Ian
- Date: 2019
- Subjects: Chrysoblephus laticeps -- Climatic factors , Chrysoblephus laticeps -- Physiology , Sparidae -- South Africa -- Climatic factors , Reef fishes -- South Africa -- Climatic factors , Fish populations -- South Africa -- Climatic factors , Fish populations -- Measurement , Fish populations -- Monitoring , Fisheries -- South Africa -- Environmental aspects , Ocean temperature -- Physiological effect -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76541 , vital:30599
- Description: The persistence of harvested fish populations in the Anthropocene will be determined, above all, by how they respond to the interacting effects of climate change and fisheries exploitation. Predicting how populations will respond to both these threats is essential for any adaptive and sustainable management strategy. The response of fish populations to climate change is underpinned by physiological rates and tolerances, and emerging evidence suggests there may be physiological-based selection in capture fisheries. By quantifying important physiological rates of a model species, the endemic seabream, Chrysoblephus laticeps, across ecologically relevant thermal gradients and from populations subjected to varying intensities of commercial exploitation, this thesis aimed to 1) provide the first physiologically grounded climate resilience assessment for a South African linefish species, and 2) elucidate whether exploitation can drive populations to less physiologically resilient states in response to climate change. To identify physiologically limiting sea temperatures and to determine if exploitation alters physiological trait distributions, an intermittent flow respirometry experiment was used to test the metabolic response of spatially protected and exploited populations of C. laticeps to acute thermal variability. Exploited populations showed reduced metabolic phenotype diversity, fewer high-performance aerobic scope phenotypes, and a significantly lower aerobic scope curve across all test temperatures. Although both populations maintained a relatively high aerobic scope across a wide thermal range, their metabolic rates were compromised when extreme cold events were simulated (8 °C), suggesting that predicted future increases in upwelling frequency and intensity may be the primary limiting factor in a more thermally variable future ocean. The increment widths of annuli in the otoliths of C. laticeps from contemporary and historic collections were measured, as a proxy for the annual growth rate of exploited and protected populations. Hierarchical mixed models were used to partition growth variation within and among individuals and ascribe growth to intrinsic and extrinsic effects. The best model for the protected population indicated that the growth response of C. laticeps was poorer during years characterised by a high cumulative upwelling intensity, and better during years characterised by higher mean autumn sea surface temperatures. The exploited population growth chronology was too short to identify an extrinsic growth driver. The growth results again highlight the role of thermal variability in modulating the response of C. laticeps to its ambient environment and indicate that the predicted increases in upwelling frequency and intensity may constrain future growth rates of this species. A metabolic index (ϕ), representing the ratio of O2 supply to demand at various temperatures and oxygen concentrations, was estimated for exploited and protected populations of C. laticeps and used to predict future distribution responses. There was no difference in the laboratory calibrations of ϕ between populations, and all data was subsequently combined into a single piecewise (12 °C) calibrated ϕ model. To predict the distribution of C. laticeps, ϕ was projected across a high-resolution ocean model of the South African coastal zone, and a species distribution model implemented using the random forest algorithm and C. laticeps occurrence points. The future distribution of C. laticeps was estimated by predicting trained models across ocean model projections up to 2100. The best predictor of C. laticeps’ current distribution was minimum monthly ϕ and future predictions indicated only a slight range contraction on either edge of C. laticeps’ distribution by 2100. In order to provide policy makers, currently developing climate change management frameworks for South Africa’s ocean, with a usable output, the results of all research chapters were combined into a marine spatial model. The spatial model identified areas where C. laticeps is predicted to be resilient to climate change in terms of physiology, growth and distribution responses, which can then be prioritised for adaptation measures, such as spatial protection from exploitation. While these results are specific to C. laticeps, the methodology developed to identify areas of climate resilience has broad applications across taxa. From a global perspective, perhaps the most salient points to consider from this case study are the evidence of selective exploitation on physiological traits and the importance of environmental variability, rather than long-term mean climate changes, in affecting organism performance. These ideas are congruent with the current paradigm shift in how we think of the ocean, selective fisheries, and how they relate to organism climate resilience.
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A social realist account of constraints and enablements navigated by South African students during the four year professional accounting programme at Rhodes University, South Africa
- Authors: Myers, Lyndrianne Peta
- Date: 2019
- Subjects: Rhodes University -- Students , Accounting -- Study and teaching (Higher) -- South Africa , Education, Higher -- South Africa , Education, Higher -- Social aspects -- South Africa , Education, Higher -- Finance -- South Africa , Higher education and state -- South Africa
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/93800 , vital:30946
- Description: This dissertation is an analysis of the enablements and constraints navigated by 43 students from different academic years within the Department of Accounting, Rhodes University, in their pursuit of obtaining the postgraduate Diploma in Accounting (DipAcc) qualification. Passing this diploma year entitles students to become Trainee Accountants, which is one of the requirements for their ultimate goal of becoming a chartered accountant. In the course of semi-structured, face-to-face interviews conducted for this study, students from across the four years of the professional degree programme, shared what had helped or hindered them on their journeys to and through Rhodes University, and within the Department of Accounting at this university. Focus group discussions were then held with academics from the department, where the student participants’ experiences were shared. The responses of the members of the focus groups confirmed many of the student participants’ experiences as did interviews with representatives from the South African Institute of Chartered Accountants (SAICA). These representatives also spoke about students’ experiences at other campuses. To determine how localised the student participants’ experiences were, selected individuals from a number of other Departments or Schools of Accounting at SAICA-accredited institutions in South Africa were also interviewed. SAICA representatives also discussed the ‘pervasive skills’ which trainee accountants are expected to acquire. The perspectives from these different groups, have provided validation of the student research participants’ experiences. Critical Realism and Social Realism were used as theoretical underpinnings while Social Realism, Bernstein’s Pedagogic Device, Legitimation Code Theory and New Literacies Theory were used as explanatory theories. Using these theories, the participants’ experiences were analysed and could be understood in a different way. This dissertation reveals how this unequal privileging of individuals as a result of the existing structures is perpetuated at university level. It is the poorer students from under-resourced schools who generally struggle with the language and the practices and ways of being required for success at university. Student participants’ experiences of constraint and enablement arose primarily in the areas of the finances required for tuition and living expenses while at university; having English as a language of learning; and difficulties experienced with taking advantage of the learning opportunities within the department. Research participants also spoke about their experiences of transformation in terms of both student protests, and a mentoring programme which assisted them in gaining access to the practises and ways of being required for the discipline. In so doing they were inducted into the discipline’s community of practice. This dissertation has assisted in providing an understanding of what has helped and what has hindered students at Rhodes University, on their journeys towards obtaining the Postgraduate Diploma in Accounting qualification. It has also provided insight into the mechanisms which lie behind these experiences. This study will provide practitioners and policy-makers with the opportunity to be better informed about students’ struggles, to contemplate their interactions with students and to identify, remove or reduce unnecessarily burdensome hurdles. Equally and perhaps more importantly, this study and the work which emerges as a result of this research, will provide students with tools to assist them in their academic journeys, to manage essential hurdles, and to eliminate or avoid unnecessary hurdles.
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A sociological understanding of urban governance and social accountability: the case of Bulawayo, Zimbabwe
- Authors: Sivalo, Delta Mbonisi
- Date: 2019
- Subjects: Zimbabwe -- Politics and government -- 1980- , Municipal government -- Zimbabwe -- Harare , Municipal government -- Sociological aspects-- Zimbabwe -- Harare , Municipal government -- Citizen participation -- Zimbabwe -- Harare
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/71515 , vital:29860
- Description: This thesis seeks to understand the ways in which urban governance and urban-based civic participation interact with each other in contemporary Zimbabwe, with a particular focus on the factors influencing and shaping social accountability and effective citizen involvement in urban governance processes. This main objective is pursued with specific reference to Bulawayo, which is one of two metropolitan centres in Zimbabwe. The focus is specifically on questions around social accountability, citizen participation and centralised urban governance. In this regard, it is important to recognise that social accountability and urban governance need to be understood in the context of their inherent relationship and how these both shape and determine each other. In this respect, there is need to probe the foundations that shape the lived experiences of communities, through social accountability and urban governance, and how these pattern development and social change. Zimbabwe for over a decade now has gone through a series of economic and political crises which have impacted detrimentally on urban governance. With the economy in free-fall, local authorities have had to pursue a range of strategies to sustain themselves. These socio-economic conditions have forced a change in relations between the state, cities and citizens. Many studies have examined this regarding the politics of contestation between the ruling party (ZANU-PF), the state, and the main opposition party (MDC) in urban governance in Zimbabwe. However, this study zeros in on social accountability and how it is shaped by the prevailing socio-economic and political environment in Zimbabwe. At the same time, the lived experiences of communities vary and this variance influences and affects social accountability interventions and outcomes in cities like Bulawayo. Importantly, the thesis offers a longitudinal study which can map the contextual factors affecting and influencing social accountability in Bulawayo over time. Though recognising the debilitating effects of centralised urban governance on social accountability, the thesis also raises questions about the shifting, and often tenuous, relationship between the city and the central state, on one hand, and the city and its citizens on the other. In doing so, it considers the role of citizens, institutions and actors in responding to the impacts of urban governance and social accountability. In pursuing this thesis, a range of mainly qualitative research methods were used, including key informant interviews, focus group discussions, observation and use of documents. In the end, the thesis offers a nuanced analysis of the everyday complexities and challenges for social accountability in urban Bulawayo, Zimbabwe and thereby contributes to theorising social accountability and urban governance in Africa more broadly.
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Aiding the education agenda? the role of non-governmental organisations in learner performance and retention in Joza, Grahamstown, South Africa
- Authors: Nomsenge, Sinazo Onela
- Date: 2019
- Subjects: Non-governmental organizations , Non-governmental organizations -- South Africa -- Makhanda , Black people -- Education -- South Africa -- Makhanda , Education -- South Africa -- Makhanda , Joza Youth Hub (Makhanda) , Upstart Youth Development Project (Makhanda) , Village Scribe Association (Makhanda) , Ikamba Youth (Makhanda) , Access Music Project(Makhanda)
- Language: English
- Type: text , Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10962/76468 , vital:30568
- Description: This thesis describes the network of complexities that characterise the world and work of Non-Governmental Organisations (NGOs). It examines the ways in which organisations navigate different internal, sectoral and contextual intricacies while operating under the command of their chosen developmental mandates. This description is drawn from a sociological analysis of the internal workings of education NGOs, their external affiliations as well as the negotiations which underpin their operations and survival. Collectively, the careful illustration of these underpinnings outlines both the role that NGOs play in the performance and retention of learners in the Grahamstown-east township of Joza and also their position in the town’s basic education sector. Private and non-governmental interveners have, particularly from the closing decades of the 20th century, been conceptually and operationally deployed as panaceas of the socio-economic scarcities which continue to pervade much of the ‘developing’ world. Their involvement in the socio-economic missions of populations living in the Global South has grown both laterally and in the depth of how development is understood and defined, carried out and also measured. NGOs, as widely acclaimed institutional arms of global development imperatives, therefore assume prominent positions in framing policy and implementation models, prescribing performance benchmarks and pronouncing non-compliance. Likewise, education NGOs have obtained normative prescription status in global education policy and practice largely on the back of the Education for All (EFA) objectives, the Millennium Development Goals (MDGs) and the neo-liberal logics which have championed state retreat in favour of private sector ascendance in globalised development. This, in conjunction with the persistent struggles of educational transformation in the Global South, has given NGOs little trouble in legitimising their prominent presence in education and other sectors of socio-economic relief in these parts of the world. Little illusion remains however, in many commentary circles, of the role of NGOs in advancing development ideals, the honesty of their altruistic intents, their ideological leanings as well as their efficacy in carrying out their mandates. As such, the logics which have been used to dethrone developing state structures in order to expand the space for private intervention along with the prevailing and deepening markers of educational underperformance, have been central features of the criticisms levelled against NGOs. This thesis intervenes in these ongoing reflections by describing the role of NGOs in educational outcomes, particularly learner performance and retention in Joza. This analysis demonstrates the organisational, sector-level and broader community forces which influence not only the form which non-state interventions take on and the daily preoccupations of their carriers but broadly, the position they occupy in the town’s overall educational profile. By way of locating NGOs within Grahamstown’s educational landscape, this thesis first demonstrates, the conflicted nature of NGO operations from an international, sectoral, national, local and organisational level. The discussion then illustrates how the preoccupations of NGOs are scattered between the different communities which they occupy within these levels. Their reliance on these players demands that organisations be tactical in guarding both their survival and, at times, the conflicting allegiances which grant them different forms of legitimacy. Internal struggles which characterise this imbalance of forces results in a trade-off which often favours organisational preservation mechanisms over systemic educational overhaul. As such, while non-state interveners can be lauded for extending educational support to those who would otherwise not have such, the gains of NGO intervention are often absorbed by internal urgencies for organisational legitimacy and preservation. This, in a context which possesses a unique set of socio-economic and educational deficits that require, at the very least, radical and unbridled mediation, means that pre-existing inequalities in educational inputs and outcomes along with the resultant inequities in youth socio-economic prospects, can find refuge in the very sector whose support and intervention is sought out and justified for such. This thesis lays out the nuances of these tensions and contradictions and offers this case as a point of reference for further considerations of the persistent markers of underperformance which characterise developing communities that enjoy high concentrations of non-state educational intervention.
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