List of Titles

Constraining simulation uncertainties in a hydrological model of the Congo River Basin including a combined modelling approach for channel-wetland exchanges

- Kabuya, Pierre Mulamba

Authors: Kabuya, Pierre Mulamba
Date: 2021-04
Subjects: Congo River Watershed , Watersheds -- Congo (Democratic Republic) , Hydrologic models , Rain and rainfall -- Mathematical models , Runoff -- Mathematical models , Wetland hydrology
Language: English
Type: thesis , text , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/177997 , vital:42897 , 10.21504/10962/177997
Description: Compared to other large river basins of the world, such as the Amazon, the Congo River Basin appears to be the most ungauged and less studied. This is partly because the basin lacks sufficient observational hydro-climatic monitoring stations and appropriate information on physiographic basin properties at a spatial scale deemed for hydrological applications, making it difficult to estimate water resources at the scale of sub-basins (Chapter 3). In the same time, the basin is facing the challenges related to rapid population growth, uncontrolled urbanisation as well as climate change. Adequate quantification of hydrological processes across different spatial and temporal scales in the basin, and the drivers of change, is essential for prediction and strategic planning to ensure sustainable management of water resources in the Congo River Basin. Hydrological models are particularly important to generate the required information. However, the shortness of the available streamflow records, lack of spatial representativeness of the available streamflow gauging stations and the lack of understanding of the processes in channel-wetland exchanges, are the main challenges that constrain the use of traditional approaches to models development. They also contribute to increased uncertainty in the estimation of water resources across the basin (Chapter 1 and 2). Given this ungauged nature of the Congo River Basin, it is important to resort to hydrological modelling approaches that can reasonably quantify and model the uncertainty associated with water resources estimation (Chapter 4) to make hydrological predictions reliable. This study explores appropriate methods for hydrological predictions and water resources assessment in ungauged catchments of the Congo River Basin. In this context, the core modelling framework combines the quantification of uncertainty in constraint indices, hydrological modelling and hydrodynamic modelling. The latter accounts for channel-wetland exchanges in sub-basins where wetlands exert considerable influence on downstream flow regimes at the monthly time scale. The constraint indices are the characteristics of a sub-basin’s long-term hydrological behaviour and may reflect the dynamics of the different components of the catchment water balance such as climate, water storage and different runoff processes. Currently, six constraint indices namely the mean monthly runoff volume (MMQ in m3 *106), mean monthly groundwater recharge depth (MMR in mm), the 10th, 50th and 90th percentiles of the flow duration curve expressed as a fraction of MMQ (Q10/MMQ, Q50/MMQ, Q90/MMQ) and the percentage of time that zero flows are expected (%Zero), are used in the modelling approach. These were judged to be the minimum number of key indices that can discriminate between different hydrological responses. The constraint indices in the framework help to determine an uncertainty range within which behavioural model parameters of the expected hydrological response can be identified. Predictive equations of the constraint indices across all climate and physiographic regions of the Congo Basin were based only on the aridity index because it was the most influential sub-basin attribute (Chapter 5) for which quantitative information was available. The degree of uncertainty in the constraint Q10/MMQ and Q50/MMQ indices is less than 41%, while it is somewhat higher for the mean monthly runoff (MMQ) and Q90/MMQ constraint indices. The established uncertainty ranges of the constraint indices were tested in some selected sub-basins of the Congo Basin, including the Lualaba (93 sub-basins), Sangha (24 sub-basins), Oubangui (19 sub-basins), Batéké plateaux (4 sub-basins), Kasai (4 sub-basins) and Inkisi (3 sub-basins). The results proved useful through the application of a 2-stage uncertainty approach of the PITMAN model. However, it comes out of this study that the application of the original constraint indices ranges (Chapter 5) generated satisfactory simulation results in some areas, while in others both small and large adjustments were required to fully capture some aspects of the observed hydrological responses (Chapter 6). Part of the reason is attributed to the availability and quality of streamflow data used to develop the constraint indices ranges (Chapter 5). The main issue identified in the modelling process was whether the changes made to the original constraints at headwater-gauged sub-basins can be applied to ungauged upstream sub-basins to match the observed flow at downstream gauging stations. Ideally, only gauged sub-basin’s constraints can be easily revised based on the observed flow. However, the refinement made to gauged sub-basins alone may fail to substantially affect the results if ungauged upstream sub-basins exert a major impact on defining downstream hydrological response. The majority of gauging stations used in this analysis are located downstream of many upstream ungauged sub-basins and therefore adjustments were required in ungauged sub-basins. These adjustments consist of shifting the full range of a constraint index either towards higher or lower values, depending on the degree to which the simulated uncertainty bounds depart from the observed flow. While this modelling approach seems effective in capturing many aspects of the hydrological responses with a reduced level of uncertainty compared to a previous study, it is recommended that the approach be extended to the remaining parts of the Congo Basin and assessed under current and future development conditions including environmental changes. A 2D hydrodynamic river-wetland model (LISFLOOD-FP) has been used to explicitly represent the inundation process exchanges between river channels and wetland systems. The hydrodynamic modelling outputs are used to calibrate the PITMAN wetland sub-model parameters. The five hydrodynamic models constructed for Ankoro, Kamalondo, Kundelungu, Mweru and Tshiangalele wetland systems have been partially validated using independent estimates of inundation extents available from Landsat imagery. Other sources of data such as remote sensing of water level altimetry, SAR images and wetland storage estimates may be used to improve the validation results. However, the important objective in this study was to make sure that flow volume exchanges between river channels and their adjacent floodplains were being simulated realistically. The wetland sub-model parameters are calibrated in a spreadsheet version of the PITMAN wetland routine to achieve visual correspondence between the LISFLOOD-FP and PITMAN wetland sub-model outputs (Storage volumes and channel outputs). The hysteretic patterns of the river-wetland processes were quantified using hysteresis indices and were associated with the spill and return flow parameters of the wetland sub-model and eventually with the wetland morphometric characteristics. One example is the scale parameter of the return flow function (AA), which shows a good relationship with the average surface slope of the wetland when the coefficient parameter (BB) of the same function is kept constant to a value of 1.25. The same parameter (AA) is a good indicator of the wetland emptying mechanism. A small AA indicates a wetland that slowly releases its flow, resulting in a highly delayed and attenuated hydrological response in downstream sub-basins. This understanding has a practical advantage for the estimation of the PITMAN wetland parameters in the many areas where it is not possible, or where the resources are not available, to run complex hydrodynamic models (Chapter 7). The inclusion of these LISFLOOD-FP informed wetland parameters in the basin-scale hydrological modelling results in acceptable simulations for the lower Lualaba drainage system. The small wetlands, like Ankoro and Tshiangalele, have a negligible impact on downstream flow regimes, whereas large wetlands, such as Kamalondo and Mweru, have very large impacts. In general, the testing of the original constraint indices in the region of wetlands and further downstream of the Lualaba drainage system has shown acceptable results. However, there remains an unresolved uncertainty issue related to the under and over-estimation of some aspects of the hydrological response at both Mulongo and Ankoro, two gauging stations in the immediate downstream of the Kamalondo wetland system. It is difficult to attribute this uncertainty to Kamalondo wetland parameters alone because many of the incremental sub-basins contributing to wetland inflows are ungauged. The issue at Mulongo is the under simulation of low flow, while the high flows at the Ankoro gauging station are over-simulated. However, the pattern of the calibrated constraint indices in this region (Chapter 8) shows that the under simulation of low flow at Mulongo cannot be attributed to incremental sub-basins (between Bukama, Kapolowe and Mulongo gauging stations), because their Q90/MMQ constraint indices are even slightly above the original constraint ranges, but maintain a spatial consistency with sub-basins of other regions. Similarly, sub-basins located between Mulongo, Luvua and Ankoro gauging stations have high flow indices slightly below the original constraint ranges and therefore they are unlikely to be responsible for the over simulation of high flow at the Ankoro gauging station. These facts highlight the need for a further understanding of the complex wetland system of Kamalondo. Short-term data collection and monitoring programme are required. Important tributaries that drain to this wetland need to be monitored by installing water level loggers and periodically collecting flow data and river bathymetry. This programme should lead to the development of rating curves of wetland input tributaries. This would partially solve the unresolved uncertainty issues at the Ankoro and Mulongo gauging stations. The integrated modelling approach offers many opportunities in the Congo Basin. The quantified and modelled uncertainty helps to identify regions with high uncertainty and allows for the identification of various data collection and management strategies that can potentially contribute to the uncertainty reduction. The quantified channel-wetland exchanges contribute to the improvement of the overall knowledge of water resources estimation within the regions where the effects of wetlands are evident even at the monthly time scale. In contrast, ignoring uncertainty in the estimates of water resources availability means that water resources planning and management decisions in the Congo Basin will continue to be based on inadequate information and unquantified uncertainty, thus increasing the risk associated with water resources decision making. , Thesis (PhD) -- Faculty of Science, Institute for Water Research, 2021
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Date Issued: 2021-04

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Design of Immunobiosensors for Detection of Tumor-Associated Anti-P53 Autoantibodies: Method Development

- Adeniyi, Omotayo Kayode

Authors: Adeniyi, Omotayo Kayode
Date: 2020
Subjects: Uncatalogued
Language: English
Type: thesis , text , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/162988 , vital:41002 , 10.21504/10962/162988
Description: Introduction -- Experimental -- Label-Free Impedimetric Sensing of Anti-P53ab... -- Fluorescent detection of Anti-P53ab -- Peroxidase-like activity of Fe3O4@SiNP-APTES-Au@Pd... -- Colorimetric detection of Anti-P53ab , Thesis (PhD)--Rhodes University, Science Faculty, Department of Chemistry, 2020. , Detection and profiling of circulating tumor-associated autoantibodies (TAAbs) are useful for screening and early-stage diagnosis of asymptomatic lung cancer. Immunobiosensor technologies aimed to accomplish the highly sensitive, rapid and low-cost detection of TAAbs can improve the early-stage detection of lung cancer. Immunobiosensors for the detection of anti-P53-tumour associated autoantibodies have been developed in this work. The design of sensing interfaces with immobilized P53 protein (P53ag) as a sensing element layer on a solid interface was investigated. Several methods of detecting anti-P53-antibodies (anti-P53ab) were investigated. These methods are label-free detection using electrochemical impedance spectroscopy (EIS) and two label techniques. The label-free electrochemical techniques utilize gold electrode pre-modified with a conducting layer of electrochemically grafted phenylethylamine for covalent immobilization of P53ag. The limit of anti-P53ab detection with the label-free EIS was 103.0 pg.ml-1. The labeled technique developed utilizes fluorescent, and peroxidase-like nanomaterial labeled antibody as a detection probe. For the fluorescence detection, fluorescent silica nanoparticles were synthesized by overloading FITC into the silica matrix and conjugated to detection antibody (anti-IgG). The detection of the anti-P53ab was based on the dissolution of the silica nanoparticles to release the loaded dye as a signal amplification strategy. The fluorescence detection was carried out on a microplate, and magnetic bead modified P53-antigen platforms and limit of detection (LoD) were 42.0 fg.ml-1 and 3.3 fg.ml-1 for anti-P53ab; respectively. Fe3O4@SiNP-APTES-Au@Pd hybrid nanoparticles were synthesized, and their peroxidase-like activity and colorimetric detection were evaluated. The Fe3O4@SiNP-APTES-Au@Pd exhibited comparable activity to HRP. The Fe3O4@SiNP-APTES-Au@Pd was conjugated to protein-G-anti-IgG for the detection of anti-P53ab on a microplate and cellulose paper platforms. The LoD was 20.0 fg.ml-1 and 63.0 fg.ml-1 for the microplate and cellulose paper platform; respectively. The potential application of the designed immunobiosensor was evaluated in simulated serum samples. The developed sensors showed higher detection sensitivity, stability and had a lower detection limit for anti-P53ab when compared with the ELISA based detection. The results have provided alternative and effective quantification approaches to ELISA and a promising future for multiplexed detection of tumor-associated autoantibodies. The developed methodologies in this thesis could be applied for the detection of other autoantibodies in other cancer types and auto-immune diseases.
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Date Issued: 2020

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Umemulo and Zulu girlhood: From preservation to variations of ukuhlonipha nokufihla (respect and secrecy)

- Mntambo, Londiwe Nompilo

Authors: Mntambo, Londiwe Nompilo
Date: 2021-04
Subjects: Virginity , Zulu (African people) -- Rites and ceremonies , Zulu (African people) -- Social life and customs , Virginity -- Social aspects , Women, Zulu -- South Africa -- KwaZulu-Natal -- Social conditions , Women -- Social and moral questions
Language: English , Zulu
Type: thesis , text , Masters , MA
Identifier: http://hdl.handle.net/10962/178352 , vital:42932
Description: This study examines evolving definitions of ukuziphatha kahle that historically relied on the preservation of virginity for Zulu girls, who participate in the umemulo ceremony that marks the transition from girlhood to womanhood. It examines notions of Zulu girlhood as understood through preservation - ukugcina isibaya sikaBaba - and through respectability and secrecy - ukuhlonipha nokufihla. The study analyses how conceptions of ukuziphatha kahle (good behavior) have evolved in the context of sexual rights in the performance of Zulu girlhood. It is located in the interdisciplinary literature of global girlhood studies, and African feminist lenses of womanhood and rites of passages. The study draws from 26 interviews with Zulu women who have gone through umemulo, elder women who facilitate virginity testing and umemulo; and female relatives of women who have gone through umemulo in Estcourt, Wembezi, Paapkalius Fountain, Ntabamhlophe and Cornfields in KwaZulu-Natal. This thesis contextualises umemulo and ukuziphatha kahle (good behaviour) in democratic South Africa. Umemulo is a ritual done for a Zulu girl whose behaviour is deemed to be good. While this is clear, what constitutes ukuziphatha kahle (good behaviour) is contested. On stricter terms, ukuziphatha kahle means to be intombi nto (a virgin). The interviews with women who went through umemulo show that most of them were not virgins at the time of the ritual. The elder and younger women expressed that ukuziphatha kahle for them goes beyond the girl’s virginity. Instead, they understand it as a girl who does not have a child, and who has shown respect and obedience to her parents and elders. Strikingly, the study shows an inter-generational collusion between the younger and elder women, who maintain the outward appearance of virginity of the girls who participate in umemulo. The study argues that there are variations of ukuhlonipha (respect), which in the rights context of democratic South Africa overlap into ukufihla (secrecy). Importantly, it is clear that the concept of being a good Zulu womanhood holds and remains important for Zulu girls and women. However, the ways in which Zulu women experience and perform this is complex. The findings show that while many Zulu girls want to be seen as performing accepted good Zulu womanhood, they do so in ways that allow them to enjoy their sexual rights and pleasure. This is not a tension. , Thesis (MA) -- Faculty of Humanities, Politial and International Studies, 2021
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Date Issued: 2021-04

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Inhibitor search and variant analysis of Acetylcholinesterase

- Ras, Harnaud

Authors: Ras, Harnaud
Date: 2021-04
Subjects: Acetylcholinesterase , Alzheimer's disease , Acetylcholinesterase -- Inhibitors , Alzheimer's disease -- Chemotherapy , Cerebrovascular disease -- Treatment , Molecular mechanics Poisson–Boltzmann surface area (MM-PBSA)
Language: English
Type: thesis , text , Masters , MSc
Identifier: http://hdl.handle.net/10962/178191 , vital:42919
Description: Acetylcholinesterase (AChE) inhibition is used to treat Alzheimer's disease by increasing the availability of acetylcholine to carry nerve signals in the brain. The response to this treatment varies widely, which may be due to altered affnity to the current drugs caused by genetic variation. Various negative side-effects limit their use. As this is one of the only available therapeutic drug targets to treat Alzheimer's disease, decreasing the negative effects is of great importance. AChE is involved in biological processes that occur after acute ischemic stroke. Stroke is the third leading cause of death worldwide, and 87% of all stroke cases belong to ischemic stroke. AchEI (cholinesterase inhibitors) have been suggested to have properties that lower the risk of stroke. AChE is one of 15 verified drug targets under study for treatment of stroke. In addition to Alzheimer's disease and stroke, Lewy body disease (LBD) may be treated using cholinesterase inhibitors. The goals of this study are to find inhibitors that can potentially be used to treat Alzheimer's disease and/or stroke and to investigate variants which may affect protein dynamics and function. Two variants were analyzed, P247L and T229S. Molecular simulation of the P247L variant resulted in a disruption in protein dynamics in comparison to the wildtype. A total of 5728 molecules were screened and 10 nanosecond simulations were used to narrow down the set of compounds. The four best performing molecules were simulated for 10 nanoseconds. MM-PBSA was performed to identify molecules with high binding free energies. , Thesis (MSc) -- Faculty of Science, Biochemistry and Microbiology, 2021
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Date Issued: 2021-04

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Motivation to learn science and make sense of the concept of malleability through the traditional blast furnace in a grade 9 Physical Science class

- Kudumo, Wilfred Peter

Authors: Kudumo, Wilfred Peter
Date: 2021-04
Subjects: Science -- Study and teaching (Secondary) -- Namibia -- Kavango West , Metals -- Effect of high temperatures on , Blast furnaces , Ethnoscience -- Namibia -- Kavango West , Ubuntu (Philosophy) , Culturally relevant pedagogy , Motivation in education -- Namibia -- Kavango West , Continuity Argumentative Theory (CAT)
Language: English
Type: thesis , text , Masters , MEd
Identifier: http://hdl.handle.net/10962/177262 , vital:42804
Description: The current situation of teaching and learning science in Namibia is of great concern since it does not seem to take into consideration learners’ socio-cultural backgrounds. As a result, learners are finding that science is not relevant to their everyday life experiences and hence are not motivated to learn it. This is compounded in part by the fact that the Namibian curriculum seems to be silent on how science teachers should include learners’ socio-cultural backgrounds, for example, local or indigenous knowledge in their teaching repertoires. It is against this background that in this study I explored how mobilising the cultural practice of a traditional blast furnace (mudukuto) as an approach enables and/or constrains learners’ motivation to learn science and make sense of the concept of malleability. This is a qualitative case study underpinned by a combination of interpretive and Ubuntu paradigms. It was carried out in a rural school in Namibia, Kavango West Region, where I am currently teaching. The participants in the study were grade 9 learners and one expert community member. Focus group interviews, participatory observation, learners’ reflections, and stimulated recall interviews were used to gather qualitative data. Vygotsky’s socio-cultural theory was used as a theoretical framework and Ogunniyi`s Continuity Argumentative Theory (CAT) was used as analytical framework or lens to analyse the data. A thematic approach to analyse data was employed. That is, qualitative data were analysed inductively to come up with sub-themes and themes. The findings of the study revealed that the traditional furnace motivated the learners involved in this study to learn science and learners were able to extract science concepts on malleability from the traditional practice. The implication for this study is that when science is related to learners’ daily life or real-world experiences, they are enabled to bridge the gap from what they learn at home or in the community with school science. The study thus recommends that teachers should make an effort to integrate local or indigenous knowledge and practices to make science accessible and relevant in their classrooms. , Thesis (MEd) -- Faculty of Education, Education, 2021
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Date Issued: 2021-04

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The role of open government data in the repurposing of land administration in postapartheid South Africa : an exploration

- Manona, Siyabulela Sobantu

Authors: Manona, Siyabulela Sobantu
Date: 2021-04
Subjects: Transparency in government -- South Africa , Land reform -- South Africa , Qualitative research -- Methodology , Postcolonialism -- South Africa , Post-apartheid era -- South Africa , South Africa -- Economic conditions -- 1991- , South Africa -- Social conditions -- 1994- , South Africa -- Politics and government -- 1994- , Open Government Data (OGD)
Language: English
Type: thesis , text , Doctoral , PhD
Identifier: http://hdl.handle.net/10962/178397 , vital:42936 , 10.21504/10962/178397
Description: Almost three decades after the official end of the apartheid, South Africa has been on a sturdy path that is characterised by deepening spatial economic inequalities. A plethora of policy instruments unleashed since 1994 had not only failed to stem the tide of poverty and inequality, but had deepened them. As part of this, South Africa’s most ambitious social engineering programme – land reform -- had disappointing outcomes. Premised on a view that these apartheid continuities were embedded in South Africa’s land administration system – which was incoherent and fragmented and requiring a systemic overhaul -- the study sought to explore the potential role of Open Government Data (OGD) in the repurposing of land administration system in the post-apartheid South Africa. To achieve this goal, the study was guided by the following objectives: to explore the ontology and the state of land governance and administration in the context of the post-apartheid South Africa; to undertake an evaluation or assessment of South Africa’s land data ecosystem; and to explore the potential role of OGD in the repurposing of land administration system in the postapartheid of South Africa. This study was steeped in qualitative research methods, underpinned by primary and secondary literature review. While the study was primarily pitched on a national scale – the combination of the systems and multiple scales approaches – yielded results which dislodges solutions that are required outside of the domain of a single state. This is one glaring example of land governance complexities that straddle beyond national scale – specifically in respect of new policy trajectories on trans-national boundaries and governance of water resources. Based on the holistic ontology of land, this study concludes that land administration and land governance overarching conceptual orientation -- concerned with land use decisions made by humans at various scales from a praxis and policy perspective –constitute two sides of the same coin, the former steeped towards practice and the latter steeped towards policy. Drawing from decolonial theories the study concludes that land does not only have multiple dimensions, but it also has multiple meanings, in a manner that calls for an ontological shift away from the western ontology, towards an inclusive and holistic conceptualisation. Historiography that is anchored in de-colonial thinking of South Africa’s land governance helps us understand how and why – colonial/apartheid norms acrimoniously found their way into the post-apartheid order -- the post-apartheid institutions of modernity rest on the same hierarchies of identities, classification and pathologisation. The study concludes that, while the colonial/apartheid administration may be gone, it’s underlying power matrices continue -- i.e. capitalism/European/patriachal/white – in a manner which explains the continuities of South Africa’s spatial inequalities and the associated economic inequalities. The organising principle for land relations (including opportunities) continues to be underpinned by gender, race and class, in ways that expose the mythical dimensions of the 'post-apartheid' underbelly. While identifying the need for homogenisation and rationalistion of colonial, apartheid and post-apartheid institutions (on a national scale) that is insufficient for the transformation of the colonial situation of what is in essence a part of the global system, the study advocates for the ‘repurposing of land governance and administration’ – underpinned by de-colonial thinking. Repurposing is seen as political imaginary that would entail uncoupling thought processes and praxis from the colonial matrices of power. The study goes on to conclude that there is a definite role for Open Government Data in repurposing of land administration in the post-apartheid South Africa – as a necessary, though in and of it’s own it is an insufficient condition to achieve that ideal -- but presents an opportunity to enhance transdisciplinarity approaches and efficiencies in internal government functioning and evidence-based decision making and policy formulation processes. , Thesis (PhD) -- Faculty of Science, Geography, 2021
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Date Issued: 2021-04

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Baculovirus synergism for improved management of false codling moth Thaumatotibia leucotreta Meyr. (Lepidoptera: Tortricidae)

- Taylor, David Graham

Authors: Taylor, David Graham
Date: 2021-04
Subjects: Baculoviruses , Cryptophlebia leucotreta , Cryptophlebia leucotreta -- Biological control , Biological pest control agents , Citrus -- Diseases and pests , Codling moth , Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV)
Language: English
Type: thesis , text , Masters , MSc
Identifier: http://hdl.handle.net/10962/176942 , vital:42774
Description: Baculoviruses are an environmentally friendly and effective agent for managing lepidopteran pests. This includes the management of Thaumatotibia leucotreta (Meyrick) (Lepidoptera: Tortricidae), a serious pest of citrus in Southern Africa and a major threat to the South African citrus export industry. For more than 15 years, CrleGV-SA- based biopesticides have been used as part of an integrated pest management strategy for the control of T. leucotreta in citrus orchards in South Africa, under the names Cryptogran™ and Cryptex®. While these biopesticides have been effective during this period, there are some areas in which baculovirus use could potentially be improved. Baculoviruses are notoriously slow to kill in comparison to chemical-based pesticides, and lately, pest resistance to baculoviruses has become a major concern with the development of resistance by Cydia pomonella (Linnaeus) (Lepidoptera: Tortricidae) to its granulovirus occurring in the field in Europe. The consistent use of CrleGV-SA for more than 15 years in the field has raised concern that T. leucotreta could develop resistance to this virus, and has made it necessary to alter baculovirus-based management strategies to prevent this from occurring. A second baculovirus, Cryptophlebia peltastica nucleopolyhedrovirus (CrpeNPV), has recently been isolated and was shown to be effective against T. leucotreta. However, the interactions between CrleGV-SA and CrpeNPV are not yet understood and so it is important to test these interactions before both viruses are applied on the same orchards. Not only is it important to know whether these viruses could negatively impact each other, but it is also important to test whether they could interact synergistically. A synergistic interaction could not only provide a potential tool for the management of resistance, but it could also be exploited to improve baculovirus-based management of T. leucotreta. In this study, a stock of CrleGV-SA was purified by glycerol gradient centrifugation from T. leucotreta cadavers, while a stock of CrpeNPV purified from Cryptophlebia peltastica (Meyrick) (Lepidoptera: Tortricidae) cadavers was provided by River Bioscience (Pty) Ltd. These stocks were screened for purity by a multiplex polymerase chain reaction (mPCR) protocol designed to detect CrleGV-SA and CrpeNPV. The occlusion body (OB) density was then calculated using darkfield microscopy and a counting chamber. Both stocks were shown to be pure within the limits of the mPCR protocol, and the CrleGV-SA and CrpeNPV stocks were calculated to contain 3.08 × 1011 OBs/mL and 1.92 × 1011 OBs/mL respectively The first aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the dose mortality, in terms of lethal concentration. This was calculated using 7-day surface-dose biological assays for each virus and a 1:1 mixture of OBs of the two against T. leucotreta neonates. The lethal concentrations of each treatment required to kill 50 % of larvae (LC50) and 90 % of larvae (LC90) for each treatment were then calculated and compared using a probit regression. The mixed infection performed significantly better than either virus by itself, while each virus by itself did not differ significantly from the other. The LC50 for CrleGV-SA, CrpeNPV and the mixed infection were 1.53 × 104 OBs/mL, 1.15 × 104 OBs/mL and 4.38 × 103 OBs/mL respectively. The LC90 of CrleGV-SA, CrpeNPV and the mixed infection were calculated to be 4.10 × 105 OBs/mL, 1.05 × 105 OBs/mL, and 4.09 × 104 OBs/mL respectively. The second aspect of the interaction between CrleGV-SA and CrpeNPV that was investigated was the speed of kill. A time-response biological assay protocol was created that allowed for effective observation of the larvae. This was then used to generate time-mortality data that were analysed by a logit regression function to calculate and compare the treatments at the time of 50 % larval mortality (LT50) and the time of 90 % mortality (LT90). Each virus by itself did not differ significantly from the other, while the mixed infection took significantly longer to kill 50 % and 90 % of the larvae, suggesting that there is competition for resources between viruses during the secondary, systemic phase of infection. The LT50 for CrleGV-SA, CrpeNPV and the mixed infection were 117.5 hours, 113.5 hours and 139.0 hours respectively. The LT90 for CrleGV-SA, CrpeNPV and the mixed infection were 153.2 hours, 159.3, and 193.4 hours respectively. Finally, the composition of OBs recovered from the cadavers produced by the time-response biological assays were investigated by mPCR. A method for extracting gDNA from OBs in neonate-sized T. leucotreta larvae is described. The presence of CrpeNPV along with CrleGV-SA was noted in 4 out of 9 larvae inoculated with only CrleGV-SA. The presence of CrleGV-SA as well as CrpeNPV was noted in all but one larva inoculated with only CrpeNPV, and both CrleGV-SA and CrpeNPV were noted in all but one larva inoculated with a 1:1 mixture of the two, with one larva only being positive for CrleGV-SA. This suggests either stock contamination or the presence of covert infections of CrleGV-SA and CrpeNPV in the T. leucotreta population used in this study. This is the second study to report an improved lethal concentration of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates, and the first study to report the slower speed of kill of a mixed infection of CrleGV-SA and CrpeNPV against T. leucotreta neonates. While the improved lethal concentration of the mixed infection is a promising step in the future improvement of baculovirus-based biopesticides, it is at the cost of a slower speed of kill. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
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Date Issued: 2021-04

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Hierdie keer gaan nie maklik wees nie

- Visser, Deon Claudius

Authors: Visser, Deon Claudius
Date: 2021-04
Subjects: Creative writing (Higher education) -- South Africa , Diaries -- Authorship , Short stories, Afrikaans -- 21st century , Afrikaans fiction -- 21st century , Afrikaans fiction -- History and criticism
Language: Afrikaans
Type: thesis , text , Masters , MA
Identifier: http://hdl.handle.net/10962/178317 , vital:42929
Description: My tesis bestaan uit twee versamelings van prosa wat verwant en in noue verband met mekaar tree. Die prosa is fragmentaries en kort maar verbind met ‟n oorkoepelende storie wat in beide Afrikaans en Engels voorgelê word. Die Afrikaanse deel van my tesis ondersoek die verlede, en die Engels die toekoms. My algemene bron van inspirasie vir die struktuur en voorlegging van die tesis word verkry vanaf die klassieke raamverteller konvensie soos gebruik in One Thousand and One Nights, hierdie konvensie maak gebruik van raamfragmente wat binne ‟n groter geheel gevind kan word. Dit is juis hierdie komplekse struktuur wat dit moontlik maak om tyd, hede en verlede asook die toekoms, te kan ondersoek en uit te beeld. Verder maak dit dit ook moontlik om gekoppelde herinneringe, gedagteneigings, en fantasieverhale te kan gebruik as die dryfkrag van die oorkoepelende storie. Met betrekking tot kontemporêre fiksie vind ek die meeste aanklank en invloed by Sandra Cisneros se boek House on Mango Street. Ek het by hierdie verhaal geleer hoe om vignette en kortverhale onafhanklik maar met ‟n motief-verbinding aan mekaar te koppel. Tematies gesproke handel my tesis oor herinneringe, nostalgie, familieverhoudings, die dood asook afsluiting en aanbeweging. In terme van hierdie temas vind ek dat Nathan Trantraal se Chokers en Survivors, en Noudat Slapende Honde deur Ronelda S. Kamfer my die meeste insae gee oor die verhouding tussen Afrikaans en Engels in die literatuur. Verder is Loftus Marais se taalgebruik en die vermenging van taal in Staan in die Algemeen Nader aan Vensters ook insiggewend. , Thesis (MA) -- Faculty of Humanities, School of Languages and Literatures, 2021
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Date Issued: 2021-04

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Customer perceptions on Customer Relationship Management (CRM) and its possible influence on Revenue Management (RM) at a selected water board in South Africa

- Manyonganise, Joshua Anesu

Authors: Manyonganise, Joshua Anesu
Date: 2021-04
Subjects: Customer relations -- Management , Revenue management -- South Africa -- Eastern Cape , Municipal government -- South Africa -- Eastern Cape , Municipal services -- South Africa -- Eastern Cape , Water-supply -- South Africa -- Eastern Cape , Amatola Water (Utility) , South Africa. National Water Act, 1998
Language: English
Type: thesis , text , Masters , MCom
Identifier: http://hdl.handle.net/10962/177214 , vital:42800
Description: The primary activity of water boards is to provide water services (bulk portable, and bulk wastewater) to other water services institutions within its respective service areas. They may perform other activities under conditions set out in the Water Services Act of 1997. Water boards’ revenues come from the municipalities they deliver services to. Not all municipalities have been paying for the services delivered to them, which led to the aim of this study being to gauge the perceptions of Water Board X and Water Board X’s customers of selected Customer Relationship Management (CRM) factors (service quality, customer involvement, customer value, information technology, and management commitment) that may possibly influence Revenue Management (RM). This could possibly assist Water Board X in the future to improve its revenue and debt collection. This thesis employed an interpretivist qualitative research methodology to explore its research aims and objectives. Open-ended semi-structured interviews were conducted with thirteen participants from Water Board X and four municipalities which Water Board X provides services. The data collected from the interviews were analysed manually through thematic analysis. The outcome of the interviews noted that an organisation that delivered high levels of service quality to its customers, could possibly improve its RM as the customers are of the opinion that their needs and requirements have been met and would be willing to pay for the services rendered. It was furthermore found that an organisation that involves its customers could possibly improve its RM as the organisation constantly communicates with its customers during, for example, the different stages of a project to ensure that the organisation does not deliver a project that does not meet the customers’ requirements at the end of the project life cycle. In addition the use of information technology played a pivotal in an organisation as the use of information technology assisted to develop effective methods in customer relationship management such as, data management, improving communication within the organisation, and with the customers, and the decision making. Furthermore, this study suggested the importance for an organisation to add value to the services that they deliver and for an organisation’s management to be committed to ensure that their customers’ expectations and requirements are met. The findings of the study suggest that CRM factors (service quality, customer involvement, customer value, information technology, and management commitment) could influence RM, and it is suggested that Water Board X adopts CRM strategies accordingly to improve its RM. Some of these strategies include adopting a coherent and sustainable revenue strategy through the use of appropriate tariff structures that are simple, equitable, affordable, financially sustainable, and transparent for all; showing commitment by prioritising water loss management and by properly auditing water supplies and water treatment revenue while increasing efficiency in supply and revenue recovery as this allowed Water Board X to better serve its customers, improve its financial standing, and allocate funding for water infrastructure upgrades and to adopt technologies that are on the market as these technologies can detect leakages, manage payments, control water flow and transmit data. , Thesis (MCom) -- Faculty of Commerce, Department of Management, 2021
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Date Issued: 2021-04

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