Octa carboxy metal (II) phthalocyanine covalent films as pH sensitive electrochemical sensor for neurotransmitters
- Authors: Moyo, Iphithuli
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424525 , vital:72161
- Description: Octa acyl chloride metallophthalocyanines of cobalt (CoOAClPc) and iron (FeOAClPc) were synthesized and characterized using spectroscopic and electrochemical techniques. The metallophthalocyanines were fabricated as thin films onto phenylethylamine (PEA) pre-grafted Au electrode following a covalent amide reaction. The spectroscopic and electrochemical characterization confirmed the modification of the bare Au with PEA monolayer thin film (Au-PEA) and the covalent immobilization of MOAClPc to yield Au-PEA-MOAClPc (where M is Co and Fe). The acyl chloride functional groups were hydrolyzed forming pH sensitive thin films of terminal carboxylic acid (-COOH) functional groups (Au-PEA-MOCAPc). The Au-PEA-MOCAPc electrode exhibited pH selectivity and sensitivity properties towards the negatively charged [Fe(CN)6]3-/4- and positively charged [Ru(NH3)6]2+/3+ redox probes. The Au-PEA-MOCAPc electrodes were studied for their electrocatalytic and electroanalytical properties towards the detection of catecholamine neurotransmitters; dopamine (DA), epinephrine (EP) and norepinephrine (NOR). The electrodes were further investigated in the screening of ascorbic and uric acids by means of pH sensitive functional groups. The modification process exhibited good reproducibility. Excellent electrocatalytic and electroanalytical properties were observed. The limits of detection (LOD) determined using 3σ/m was found to be 64 nM, 0.22 μM and 0.17 μM for DA, EP and NOR respectively using Au-PEA-CoOCAPc. For Au-PEA-FeOCAPc, the LOD was found to 0.24 μM, 0.45 μM and 0.34 μM for DA, EP and NOR respectively. The Au-PEA-MOCAPc electrodes screened off the strong interferents, ascorbic and uric acid. The Au-PEA-FeOCAPc electrode was evaluated for its potential application in real sample analysis using new born calf serum, and it showed excellent percentage recoveries. , Thesis (MSc) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Origin and metallogenic significance of alkali metasomatism in the Paleoproterozoic Mapedi Formation, Kalahari Manganese Field, South Africa
- Authors: Ikwen, Emmanuella Biye
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424632 , vital:72170
- Description: The occurrence of alkali-rich metasomatic assemblages has been widely reported in various regions of the Kalahari Manganese Field (KMF). This alkali metasomatism has been characterized by the secondary introduction of elements such as K, Na, Li, Ba, P, V, Zn, As, amongst others. This study further explores the possibility of widespread alkali metasomatism in the KMF by reporting on and examining the occurrence of sugilite and other alkali-rich minerals at the contact between the Transvaal and Olifantshoek Supergroups in the Hotazel Mine area of the north-eastern KMF. The lithologies observed at the contact show macroscopic (such as cross cutting veins) and microscopic evidence of hydrothermal alteration. Using analytical methods such as X-ray diffraction, X-ray fluorescence, and scanning electron microscopy, results showed that in the north-eastern region of the KMF, the metasomatism observed at the Transvaal-Olifantshoek contact is mainly characterized by enrichment in sodium, and the occurrence of sodium minerals, predominantly in the form of aegirine. The aegirine forms exclusively in the quartzites of the Mapedi Formation along with minerals such as sugilite, baryte, banalsite, amongst others. Albite also occurs within the quartzites, but also within the Mapedi red shales. The secondary nature of these minerals is established by geochemical comparisons with pristine, as well as alkali-metasomatized samples of the same formation which were obtained from other parts of the KMF and Postmasburg. These comparisons showed that the Mapedi quartzites in the north-eastern KMF have undergone extensive oxidation compared to samples of the same formation which were obtained from Postmasburg. The north-eastern quartzites have an average hematite abundance of 17 wt.% compared to Postmasburg quartzite which have an average of 7 wt.% hematite. Furthermore, some quartzite samples contained up to 40 wt.% in hematite content. The comparisons also showed that Mapedi quartzites from the north-eastern KMF are substantially more sodium enriched compared to Mapedi quartzites from the Postmasburg region, which on average have sodium oxide content below detection limits. Geochemical comparisons were made between pristine Hotazel Formation samples from north-western KMF (Gloria Mine) and samples obtained from the north-eastern KMF (Hotazel Mine). Results showed that the samples obtained from the top of the Hotazel Formation (in the Hotazel mine area) are likely altered hematite lutite and not Banded Iron Formation, evident by their substantially high manganese oxide content (over 30 wt.% in some cases). When compared to pristine samples, the lutite also showed evidence of hydrothermal alteration, predominantly in the form of phosphate and barium enrichment, evident by the occurrence of baryte and apatite. The alkali metasomatism occurring at the contact between the Transvaal and Olifantshoek Supergroups was shown to be predominantly characterized by enrichment in Na, K, Li, Al, Ba, Sr, and P. The metasomatism characterized in this study was also proposed to possibly post-date an earlier metasomatic event which was characterized by leaching of silica and extensive oxidation of the rocks observed at the Transvaal-Olifantshoek contact in the north-eastern KMF. The occurrence of the alkali-rich minerals outlined above geochemically parallels other alkali-rich metasomatic assemblages reported in other parts of the KMF, as well as in the Postmasburg Manganese Field. Thus, based on the consistent occurrence of secondary, alkali-rich mineral assemblages across the KMF, characterized by the common occurrence of aegirine along with minerals such as sugilite and albite, there is evidence of a large-scale alkali metasomatism in the KMF. This study also explores the possible role that the Transvaal-Olifantshoek unconformity might have played in acting as a major conduit for fluid propagation because the observed mineral assemblages occur right at the contact between the Hotazel and Mapedi Formations. The occurrence of the alkali-rich minerals predominantly around the unconformity, as well as the relative depletion of phosphates in stratigraphically deeper parts of the Hotazel suggest that the fluid metasomatism was aided by the Olifantshoek-Transvaal unconformity surface. This study concludes that there is evidence for a strong link between the metasomatism occurring at the contact between the Hotazel and Mapedi formations (in the north-eastern KMF) and what is observed in the broader KMF region. , Thesis (MSc) -- Faculty of Science, Geology, 2023
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- Date Issued: 2023-10-13
Perceptions of African musical arts education in foundation and intermediate phases in government schools as seen through the South African academy since 2011: an exploration through meta-ethnography
- Authors: Chirombo, Ilana Elize Caroline
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425366 , vital:72233
- Description: The aim of this study is twofold: first, to understand meta-ethnography as a tool of synthesis; second, to use this methodology to explore perceptions of African musical arts education in the Foundation and Intermediate Phases in government schools in South Africa after 2011. Meta-ethnography is a methodology used to synthesise qualitative material by means of seven distinct phases: getting started; deciding what is relevant to the initial interest; reading the studies; determining how they are related; translating the studies into one another; weaving them together into a synthesis; and expressing the synthesis. This study synthesises five articles discovered through a deep search of the literature. Through the process of synthesis, a narrative emerges that connects past prejudice in music education in South Africa to present day educational inequality, one that looks towards a future in which children’s agency is harnessed in the multicultural world we live in to teach music in a relevant, contextual way. The synthesis extracts perceptions on colonialism and apartheid; educational access; post-apartheid curricula; music education pedagogies; informal music making; children’s games and agency; into the classroom; and how to assess. These themes weave a clear perspective on African musical arts education, and a reciprocal synthesis of the views of the articles’ authors. This study finds meta-ethnography to be a rigorous, understandable methodological tool for qualitative synthesis, one which serves the purpose of researchers, no matter the depth of their engagement with the synthesis. , Thesis (MMus) -- Faculty of Humanities, Music and Musicology, 2023
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- Date Issued: 2023-10-13
Phonological awareness skills of emergent bilingual Rumanyo-English learners
- Authors: Karupu, Erwina Mushinga
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425100 , vital:72210
- Description: This thesis is an account of a cross-sectional study which focused on investigating Phonological Awareness (PA) in emergent Rumanyo/English bilingual learners. PA and its contribution to reading fluency were investigated among 47 third grade learners with an average age of 9. 19, at a Namibian School, for which Rumanyo is the language of instruction and English, the first additional language. This cross-sectional study examines two levels of PA: Syllable awareness and phoneme awareness. Measures included three subtasks: identification, segmenting and deletion. Reading fluency was measured through oral reading fluency and silent reading. The findings suggest that learners’ levels of PA are still developing with learners performing better on syllable awareness measures than on phoneme awareness. Reading fluency results evince low levels of proficiency in Rumanyo and in English, an average level of proficiency was recorded. To determine the relationship between PA and reading fluency, a Correlation Matrix was run and followed later with a linear regression. The findings demonstrate that syllable awareness predicted reading fluency in Rumanyo, whilst phoneme awareness did not show any association and as such, the model fit did not show any relationship either. With regards to English, neither syllables nor phonemes were a predictor of reading fluency. The study further examined to what extent the phonology of Rumanyo transferred to English. , Thesis (MA) -- Faculty of Humanities, Linguistics and Applied Language Studies, 2023
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- Date Issued: 2023-10-13
Phylogeography of two small owl species in South Africa: population genetics and phenotypic variation in the African Barred Owlet (Glaucidium capense) and the African Scops Owl (Otus senegalensis)
- Authors: Balmer, Jonathan Peter
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424369 , vital:72147
- Description: Embargoed. Expected release date in 2025. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-10-13
Phytoplankton and aquatic macroinvertebrate assemblages from coastal and inland lakes of South Africa
- Authors: Nkibi, Esethu
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424435 , vital:72153
- Description: Freshwater lakes are generally defined as permanent natural standing water bodies, with some of them having a direct and indirect connection with groundwater, rivers, and the ocean. Freshwater lakes provide essential socio-economic and ecological goods and services including recreation, aesthetic, support aquatic biodiversity, food in a form of fisheries and water for domestic use. Given their critical role in sustainability in providing socio-economic services, freshwater lakes are among the most threatened ecosystems globally due to intense human impacts over the last decades. South Africa has limited freshwater lakes, which according to the National Biodiversity Assessment (NBA 2018), we know little about their current biology except historic aquatic biodiversity studies conducted in the early 1940s. There are no management strategies in place to protect and conserve freshwater lake biodiversity and important ecosystem services. This thesis aims to: (1) produce a biodiversity inventory of phytoplankton and aquatic macroinvertebrate species and, (2) investigate important environmental drivers responsible for phytoplankton and aquatic macroinvertebrate species composition from six South African freshwater lakes. It was hypothesized that the three lake types will show different phytoplankton and aquatic macroinvertebrates species composition attributed by the geographical region (coastal and inland lake) and related physico-chemical parameters. Study sites consisted of two Northern KwaZulu-Natal coastal lakes (hereafter Coastal Lakes, CL) i.e., Lake Sibaya, Lake Mzingazi; two fresh inland lakes (hereafter Fresh Inland Lakes, FIL) i.e., Lake Banagher fresh and Lake Tevrede Se Pan; and two inland salt lakes (hereafter Salt Inland Lakes, SIL) i.e., Lake Banagher salt and Lake Chrissiesmeer, all inland lakes are situated in Mpumalanga province, together with other Pans making up the Mpumalanga Lake District of South Africa. The study sites were categorized based on their geographical position i.e., coastal vs inland and physico-chemical characteristics i.e., the presence and absence of aquatic vegetation, dominate substrate, salinity and different physico-chemical concentration i.e., Temperature, Dissolved Oxygen. Aquatic macroinvertebrates were collected from four littoral zone sites (< 1-meter depth) around each lake, whereas phytoplankton samples were collected from four water column sites (> 5-meters depth) and (0.5-meter depth) from the water surface at each lake during summer and winter season. The results were consistent with our hypothesis that both phytoplankton and aquatic macroinvertebrate species composition were influenced by physico-chemical parameters and that the differences in salinity concentration and aquatic vegetation between CL, FIL, and SIL were the driving factors for phytoplankton and aquatic macroinvertebrate species composition. In summary, one hundred and twenty-two phytoplankton taxa were collected and identified during this study, belonging to seven Phyla which included Chlorophyta, Bacillariophyta, Cyanophyta, Chrysophyta, Dinophyta, Euglenophyta, and Cryptophyta. The most abundant phytoplankton groups were Bacillariophyta and Chlorophyta. Phytoplankton relative taxa abundance, Pielou’s evenness, taxa richness, and Shannon diversity were significantly different between lake types. Aquatic macroinvertebrates, on the other hand, summed up to 10 orders, 67 families, and 80 taxa. The most abundant group were the order Coleoptera, Hemiptera, Odonata, and Gastropoda. Aquatic macroinvertebrate relative taxa abundance, taxa richness, and Shannon diversity were also significantly different between lake types. Aquatic macroinvertebrate relative taxa abundance, Pielous evenness, and Shannon diversity index were not significant between seasons, and only taxa richness was significant. Canonical analysis of principal coordinates (CAP) results further showed unique and distinct phytoplankton and aquatic macroinvertebrates community composition between lake types. The present study provides baseline biodiversity inventory (or species list) for important lake ecosystems biological indicators i.e., phytoplankton and aquatic macroinvertebrates and species composition in relation to lake type for six freshwater lakes in South Africa. Furthermore, the study provides empirical evidence that will inform policy and the development of management strategies for freshwater lakes in South Africa which is currently missing. The current study will also contribute to the next National Biodiversity Assessment Report (2024), concerning the freshwater lakes biological data deficiency noted in the previous NBA (2018) report. The study will also fill up the gaps to better understand species composition in lake systems and how they function which is currently limited. , Thesis (MSc) -- Faculty of Science, Zoology and Entomology, 2023
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- Date Issued: 2023-10-13
Prediction of mass spectra using an ab initio approach
- Authors: Novokoza, Yolanda
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/${Handle} , vital:72818
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Quantifying the training demands of an amateur women’s Rugby union team using Global Positioning System
- Authors: Mbane, Nomabhelu
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424289 , vital:72140
- Description: Rugby union is a dynamic sport that has grown to not only be played by men but by women too. The professionalisation of the sport that happened in 1995 developed the game immeasurably including the focus given to its scientific research. This is important as literature on the demands of the game has become vital in improving the performance of Rugby union players (Deutch et al., 1998; Kay and Gill, 2004; Kruger, 2012). Scientific evidence-based data on the physical and physiological demands is imperative in the planning and setting up of training regimes (Deutch et al., 1998; Kay and Gill, 2004; Kruger, 2012). Unfortunately, the growth in the participation of women’s Rugby union has not been matched with scientific evidence-based literature that seeks to improve the performance of this population of players. Therefore, due to the unavailability of match-play during the COVID-19 outbreak, this study aimed to quantify the physical and physiological demands of training sessions of amateur women’s Rugby union players from the Sarah Baartman District, South Africa using Global Positioning System (GPS). The training’ data collected was compared to previous literature, including studies that also focused on match-play. Furthermore, players were categorized into forwards and backs, allowing for the comparison between the two playing categories. An exploratory, descriptive, observational, and comparative research design was used for the current study. The physical and physiological demands of eighteen women Rugby union players (eight forwards and ten backs) aged between 18 – 36 years old were assessed during training (for a total of nine sessions). To inform the participants’ characteristics, the players’ demographic, and anthropometric characteristics (age, stature, and body mass) were obtained. Using GPS and Zephyr technology the players’ training physical (time spent in speed zones, maximum speed, total distance travelled, number of impacts in the various impact zones) and physiological (heart rate) demands were explored. Statistical analysis methods including descriptive, independent t-test, one-way and two-way ANOVA tests were employed to analyse the data and evaluate the differences between forwards and backs. The mean age and stature for all players was 25,44±5,6 years and 1,60±0,06 m respectively, with no significant differences found between backs and forwards. With regards to body mass, forwards weighed 82,0±9,4 kg while backs weighed significantly lighter at 58,0±5,8 kg. Significant differences (p < 0,05) were found for all players in the time spent in speed zones and the number of impacts in impact zones. When all forwards’ and backs’ physical and physiological demands were compared the results showed no significant differences. The average time spent in all six speed zones combined was 11,41 and 11,62 mins for forwards and backs, respectively. The maximum speeds reached by forwards (21,35±5,72 km/h) and backs (22,85±3,88 km/h) were similar. All players combined travelled an average total distance of 2,14±0,76 km. The total number of impacts in all six impact zones, totalled 116 impacts for forwards and 97 for backs. Heart rate responses recorded for forwards and backs were 139±15 bpm and 134±13 bpm. Based on the findings of this study, the training intensity of amateur women’s Rugby union was lower than the demands experienced in the training and match-play of previous research. It was also observed that there was no specificity with regards to the training programs allocated between forwards and backs of this study. Further research on amateur women’s Rugby union is required to characterise training and match-play demands of these players. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
Quantifying the work demands of municipal waste workers to determine physical workload and perception
- Authors: Mamabolo, Lerato
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424267 , vital:72138
- Description: Objective: This study aimed to quantify physical and perceptual workloads through the nature of the work demands of municipal waste workers. Waste workers investigated were waste collectors, street sweepers [or public cleansers], drivers and mechanics. Methods: 154 City of Tshwane municipal waste workers volunteered to participate in the study. Observation-based tools were used to measure physical workload namely, the RAMP 1 and 2, REBA and RULA, and the hand-held dynamometer was used for pushing and pulling tasks. Subjective perceptual questionnaires were used to measure Perceptual load namely the NASA TLX and the QWIQ. Results: Differences in physical workload were evident between the occupation groups. Round bin collection was the waste collection type pertaining to the highest work-related risk of musculoskeletal development. Public cleansers and flatbed truck collectors' results displayed lower task-related risks associated in relation to the other occupations. Significant differences were found between the groups, particularly between waste collectors and drivers [had high workload outputs] in relation to public cleansers [low workload] for both perceptual workload tools. A significant difference was found in the mental and physical demands, as well as the organisational constraints and quantitative workloads. Mechanics showed no significant differences between groups but had high levels of frustration. Conclusion: A relationship between physical and perceived workload intensity is evident. development of musculoskeletal diseases and injury shall incur if measures are not reinstated. , Thesis (MSc) -- Faculty of Science, Human Kinetics and Ergonomics, 2023
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- Date Issued: 2023-10-13
Racism against Black soccer players in the English Premier League
- Authors: Zinyemba, Douglas Takudzwa
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425300 , vital:72227
- Description: This study analyses racism against black players in the English Premier League. To that end, this thesis studies online articles published between 2018 and 2021 by two British tabloids, namely, The Daily Mail and The Sun, to make sense of the various ways in which black soccer players experience racism. This thesis uses the theoretical concept of “racial xenophobia” to analyse and understand expressions of antipathy towards black players playing in the Premier League. A key finding in the thesis suggests that fans and players racially abuse black players in the stadiums by liking them to animals and treating them as sub-human. Another finding in the study is that fans use the bad performances of black players as an excuse to racially abuse them via social media platforms. Social media in the 21st century has now accelerated the rate at which racism is perpetrated as fans now have more access to players through their accounts. The study also found that tabloids do not only report about racist abuse but are also guilty of portraying black players in racially stereotypical ways. This research concludes that racism against black players remains a constant feature of football in the English Premier League from the time black players started to feature in the sport in the 1970s. , Thesis (MA) -- Faculty of Humanities, Political and International Studies, 2023
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- Date Issued: 2023-10-13
Relating vegetation distribution to cycles of erosion and deposition in the Kromme River wetlands
- Authors: Jarvis, Samuel Cameron
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424582 , vital:72166
- Description: The role of geomorphic disturbance has been increasingly recognized as fundamental in the creation and functioning of wetlands. This is true of the Kromme River wetland which has been formed through repeated cycles of erosion and deposition. However, the response – and influence – of wetland plants to these sorts of disturbance has not been investigated. This study sought to fill this knowledge gap by classifying vegetation communities over a range of hydrological and geomorphic disturbance regimes that have happened over the last few decades, and relating those vegetation communities to environmental factors. The study identified seven vegetation communities based on their species composition and abundance, which were related to geomorphic disturbance events. A conceptual model that accounts for vegetation distribution in the Kromme wetland was developed. Soil saturation was the most important factor explaining vegetation community distribution, which, in turn, is influenced by cycles of erosion and deposition. Following an erosional event on the valley floor, Prionium serratum dominated wetland is converted to a number of other vegetation communities. On the floodplain surface adjacent to the eroded gully, the Prionium serratum dominated wetland is transformed over time to Cynodon dactylon and Sporobolus fimbriatus communities. Prionium serratum clumps immediately adjacent to the recently incised gullies are able to persist, having sufficient access to water. Within the newly formed gullies, Juncus lomatophyllus colonizes the gully beds flooded to a shallow depth, Miscanthus capensis colonizes the gully bars and Setaria incrassata colonizes the exposed gully banks. Localised depositional features close to the thalweg in the gully are colonized by Prionium serratum seedlings and vegetative propagules. These plants represent the regenerating phase of Prionium serratum wetland, which also colonizes depositional floodouts downstream of the newly-formed gully. The Stenotaphrum secundatum community dominates drier, more elevated areas of the floodout. Over time, as the gully fills, Prionium serratum expands beyond the gully onto the valley floor, to replace the floodplain communities Cynodon dactylon and Sporobolus fimbriatus. Over time, Prionium serratum is thought to colonize the valley floor as the gully fills, stabilising it and promoting diffuse flow. Many restoration efforts in damaged palmiet wetlands have been focused on the preservation of intact palmiet communities upstream of erosional headcuts, with limited understanding of vegetation dynamics associated with the cut-and-fill cycles that naturally occur in these wetlands. Understanding the regeneration of Prionium serratum following erosional events is thus important for wetland restoration, as it should focus more attention on promoting palmiet restoration on depositional floodouts downstream of eroded gullies. A secondary aim of this study was to explore the possibility of mapping palmiet communities in Kromme River wetland using remote sensing techniques. Using a combination of ground-truthed data from this and previous studies in the Kromme River wetland, together with raster layers derived from a LiDAR survey, an overlay analysis was developed to effectively map the distribution of the Prionium serratum dominated community. The overlay was created using a machine learning library in RStudios known as Rpart. The results found that the model were 91% effective in classifying the distribution of the Prionium serratum community. A secondary finding was that the inclusion of a Relative Elevation Model in the overlay analysis allowed for the identification of Prionium serratum communities vulnerable to degradation following previous geomorphic disturbance events and those Prionium serratum communities that are likely to persist following a geomorphic disturbance event. , Thesis (MSc) -- Faculty of Science, Geography, 2023
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- Date Issued: 2023-10-13
Remote sensing as a monitoring solution for water hyacinth (Pontederia crassipes) in the context of the biological control programme at Hartbeespoort Dam
- Authors: Kinsler, David Louis
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424599 , vital:72167
- Description: Water hyacinth (Pontederia crassipes (C.Mart.) Solms (Pontederiaceae)) is a significant aquatic weed both globally and in South Africa. Despite notable success with biological control of other invasive macrophytes, the plant remains as a problematic weed in many aquatic systems in South Africa, particularly due to the eutrophic status of many of its water systems, as well as the plant’s tolerance to cooler climatic conditions than most of its existing biological control agents. Hartbeespoort Dam, located about 30 kilometres west of Pretoria, South Africa, has been infamously infested with water hyacinth for decades, which impacts the important socioeconomic utility of the dam and functioning of natural ecological processes in the system. The dam has a long history of efforts to control water hyacinth, which include widespread herbicidal spray, mechanical removal and classical biological control programmes since the early 1990s - mostly with limited or short-lived success. However, after the introduction of a new, cold-tolerant biological control agent, Megamelus scutellaris Berg (Hemiptera: Delphacidae) in 2018 with an inundative release strategy, the water hyacinth dropped significantly from a maximum cover of about 45 percent (819 hectares) down to less than two percent (40 hectares) over a three-month period (November 2019 – January 2020). This was significant, as it marked the first successful biological control of water hyacinth in a eutrophic, temperate system in South Africa. However, due to the scale of Hartbeespoort Dam (1820 hectares) and the high spatiotemporal variation of the floating mats across time and space, quantifying and monitoring these rapid changes has proved difficult. In response to this problem, this thesis proposed a remote sensing solution to address the need for accurate, timely and readily accessible monitoring data of the water hyacinth population on the dam. Leveraging the temporally frequent (< 5 days revisit time) Sentinel-2 multispectral satellite data, as well as the powerful cloud-computing resources of Google Earth Engine, this thesis developed and deployed a relatively simple and robust index-based decision tree classification method to demonstrate the value of these technologies as an effective monitoring and analysis tool for monitoring large macrophyte infestations. To this end, several challenges had to be overcome in order to produce easily accessible data that was accurate and reliable. For example, due to the size of the Sentinel-2 Level-1C image dataset from August 2015 to March 2021 (n = 654), an automated process of filtering out clouded images was required. Additionally, the co-presence of algal and cyanobacterial blooms necessitated the development of a novel index, coined the Algae Resistant Macrophyte Index (ARMI), to deal with the challenges of accurate macrophyte detection. The high spatiotemporal variability of the floating mats meant that a typical, location-based confusion matrix as a means of assessing the accuracy of the decision tree classifier required a different approach which compared the total classified areas with higher resolution images. This thesis aims to demonstrate the utility of remote sensing tools to provide effective monitoring information to managers, researchers and other stakeholders. There is scope to expand to more areas in South Africa and beyond and may prove an invaluable tool to augment and support on-going and future macrophyte monitoring programmes. , Thesis (MSc) -- Faculty of Science, Geography, 2023
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- Date Issued: 2023-10-13
Screening isolation and biological characterization of antibacterial secondary metabolites from macrofauna endemic to the southern African coast
- Authors: Njanje, Idris
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431944 , vital:72817
- Description: Access restricted. Expected release date in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Selected medicinal plants leaves identification: a computer vision approach
- Authors: Deyi, Avuya
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424552 , vital:72163
- Description: Identifying and classifying medicinal plants are valuable and essential skills during drug manufacturing because several active pharmaceutical ingredients (API) are sourced from medicinal plants. For many years, identifying and classifying medicinal plants have been exclusively done by experts in the domain, such as botanists, and herbarium curators. Recently, powerful computer vision technologies, using machine learning and deep convolutional neural networks, have been developed for classifying or identifying objects on images. A convolutional neural network is a deep learning architecture that outperforms previous advanced approaches in image classification and object detection based on its efficient features extraction on images. In this thesis, we investigate different convolutional neural networks and machine learning algorithms for identifying and classifying leaves of three species of the genus Brachylaena. The three species considered are Brachylaena discolor, Brachylaena ilicifolia and Brachylaena elliptica. All three species are used medicinally by people in South Africa to treat diseases like diabetes. From 1259 labelled images of those plants species (at least 400 for each species) split into training, evaluation and test sets, we trained and evaluated different deep convolutional neural networks and machine learning models. The VGG model achieved the best results with 98.26% accuracy from cross-validation. , Thesis (MSc) -- Faculty of Science, Mathematics, 2023
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- Date Issued: 2023-10-13
Silica supported sulfuric acid-catalysed one-pot processes for the synthesis of n-heterocycles
- Authors: Ndagano, Urbain Nshokano
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431921 , vital:72815
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Chemistry, 2023
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- Date Issued: 2023-10-13
Singing madness: three performative analyses of the “mad scene” from Lucia di Lammermoor
- Authors: Le Kay, Jo-Nette
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/425377 , vital:72234
- Description: This study describes three internationally recognised sopranos and their presentations of character psychology on stage, during their performances of the famous “mad scene” from Gaetano Donizetti’s opera Lucia di Lammermoor. These sopranos are Joan Sutherland, Mariella Devia, and Lisette Oropesa. I use Margaret Kartomi’s (2014) model of performativity to interpret the “madness” depicted by the three selected sopranos, as based on my interpretations of commercially released audio-visual recordings of their performances in the role of Lucia. Through analysing these performances with the help of Kartomi’s performativity model (which focuses on persona, emotion-and intersubjectivity, and reception), my research determines – with speculative interpretation, and within the reasonable limits of standard psychiatric frameworks – which mental illnesses the sopranos can be understood to have portrayed in their interpretations of the role of Lucia. The study’s goal is not to make an accurate mental health diagnosis of someone’s portrayal of a fictional character. (Considering the fact that one cannot make accurate mental health diagnoses for people who do not exist.) Rather, my focus is to discover which dramatic and possibly musical characteristics are utilised to perform this fictional character and give expressive content to her “madness”. The concept of “madness” and its psychological characterisation during performance thus becomes the framework from which to interpret and understand vocal and acting techniques related to opera in general and to bel canto more specifically. My research findings are that the three performers use facial expressions, different aspects of using the voice through bel canto singing, and body movements as a way of expression. Bel canto characteristics include coloratura embellishments, fioritura, melismas, messa di voce, squillo and chiaroscuro. The sopranos also show musical and dramatic elements in how they respond to the flute or glass harmonica during the ‘Mad Scene’ – which counts as the personae expressed by the performers. These personae are further applied in the emotional and intersubjectivity and the reception aspects of Kartomi’s performativity model. In the emotional and intersubjectivity aspect, the chorus and other characters singing on stage are read as emphasising the reaction of society on the mentally dysfunctional behaviour enacted by the sopranos. In the reception aspect, reviewers are used to filling in for audience members. I read their reactions as contributing factors in forming an understanding of the interpretations of the “mad scene” performed by the three sopranos. My reading of the three interpretations of the “mad scene” goes further by subjectively interpreting how these sopranos approximate different states of mental collapse. These readings include approximations of psychosis such as mania, dissociative personality disorder, and paranoid schizophrenic behaviour. Always, though, these mental health behaviours are identified as approximations to better understand vocal and acting techniques. , Thesis (MMus) -- Faculty of Humanities, Music and Musicology, 2023
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- Date Issued: 2023-10-13
Spatial analysis of littoral and demersal fish assemblages within the Knysna Estuary system
- Authors: Meiklejohn, Andrew Keith
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424334 , vital:72144
- Description: The Knysna Estuary is a unique system as it is the only “estuarine bay” system in the warm-temperate region of South Africa and is the largest estuary system on the southern coastline of South Africa. The Knysna Estuary has been identified as the estuary with the highest conversation priority in South Africa. The volume of research undertaken on the Knysna Estuary has led to it being rated “excellent” in terms of research productivity. However, despite this, surprisingly little work has been undertaken and published around the dynamics of fish assemblages occurring in the system, with little to no research assessing the demersal fish assemblage. The last widespread fish sampling effort that has been published was conducted in 1994, highlighting the need for an updated fish assessment with a focused sampling effort targeting both the littoral and demersal fish populations. The identification of key habitats for estuarine fish assemblages is essential for addressing estuarine conservation needs. Despite the importance of spatial data in addressing conservation planning, few estuarine studies have used spatial analyses in Geographic Information Systems (GIS) to identify conservation priority areas. Such information is critical for effective estuarine management plans. The aim of this project was to identify juvenile fish density hotspots to inform future systematic conservation planning. This study made use of two methods of sampling, seine netting to target the littoral fish assemblage and beam trawling to target demersal fish species. Two dedicated sampling trips for each sampling method were undertaken in June 2021 and March 2022 for Seine net sampling and November 2021 and March 2022 for Beam trawl sampling. Fish were identified to species level, measured (mm TL) and categorised into life history stages (i.e. settlement stage, juvenile and adult) and thereafter assigned into their various estuarine association guilds. A total of 47 species were recorded, with 42 species were caught in the seine net sampling and 24 species in the beam trawl sampling. The results from this study showed the vast extent of marine dominance in the Knysna Estuary, with marine estuarine-opportunist (MEO) species dominating catches (richness) from both sampling methods. The spatial analysis highlighted the importance of the lower “marine bay” region of the system, with the majority of estuarine guilds showing a high abundance in this region. Key fishery species and dominant fish species were identified during this study, the dominant species during the sampling effort were identified as ecologically important fish species and were dominated by adult specimens. The key fishery species sampled during this study were dominated by juvenile specimens. This highlights the role of the Knysna Estuary as a nursery area for juvenile fishery species and the contribution of the estuary to the estuarine and adjacent coastal fisheries. Key hotspots were identified for fishery species, these being the “Ashmead Channel” in the marine bay region and the “Belvidere” section of the lagoon region. Ashmead channel is sheltered backwater area while the Belvidere section is some distance from the main river channel, reducing the anthropogenic impact on these areas. The low anthropogenic utilization of these areas along with weaker water current in these regions was linked to the usage of these region by key fishery species. These areas were highlighted as important conservation hotspots with both currently not adequately protected under the current habitat sensitivity management model. , Thesis (MSc) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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- Date Issued: 2023-10-13
Species diversity and distribution patterns of three freshwater fish genera in southern Africa
- Authors: Mutizwa, Tadiwa Isaac
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431896 , vital:72813
- Description: Access restricted. Expected release in 2025. , Thesis (PhD) -- Faculty of Science, Ichthyology and Fisheries Science, 2023
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- Date Issued: 2023-10-13
Status and potential of green infrastructure to support urban resilience in Zomba City, Malawi
- Authors: Likongwe, Patrick Jeremy
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Doctoral theses , text
- Identifier: http://hdl.handle.net/10962/431821 , vital:72806 , DOI 10.21504/10962/431821
- Description: Small and medium towns with less than one million inhabitants are regarded to be the fastest growing urban centres globally, absorbing the bulk of the urban population growth. This urban growth drives the diminishing natural capital within the urban settings, resulting in compromised ecosystem services delivery, thereby rendering urban dwellers and systems less resilient to hazards and shocks. It is known that urban resilience discourse is rooted in robust, empirical assessments of the nature, composition and distribution of urban green infrastructure. Using the concept of green infrastructure, a mechanism for the delivery of ecosystem services that are multi-functional, well connected, and that integrate the grey-green infrastructure while providing room for social inclusion, anchored the research in a small city of Zomba, Malawi, which is a fast-growing city facing natural resource and ecosystem service degradation. The research therefore was set to understand the status of urban green infrastructure in Zomba over space and time as the basis for enhancing urban resilience. This was facilitated by an understanding of the spatial and temporal quantity, quality, diversity and distribution of urban greenspaces and the composition, structure, diversity and distributional differences of urban trees within different urban greenspace classes. Further to this was an investigation on the perceptions of and preferences for urban greenspaces among the different socio-demographic groups and finally the role of residents, institutions and institutional frameworks in building urban resilience through the delivery of ecosystem services. To achieve these objectives, the study used a suite of methods. First was geographical information system and remote sensing to understand the spatial and temporal changes in greenspaces within the city in terms of quantity and distribution. Ecological methods of assessing the tree species composition, diversity, population structure and distribution were also employed. To gauge the perceptions of and preferences for urban greenspaces, a survey was done, targeting users found within the urban greenspaces plus residents that claimed to have patronised the urban greenspaces. Finally, to understand the role of nature and the relevant urban ecosystem services provided towards building urban resilience, remote sensing and key informant interviews were done to enrich the literature searches on a case study of urban community efforts involved in managing Sadzi hill to reverse ecosystem disservices versus Chiperoni hill that was not managed. A general impression of declining urban green infrastructure was verified through the study. The city has indeed lost 14 % tree cover between 1998 and 2018 due to increased housing and creation of agricultural land to support the growing urban population. The city has 168 tree species with 65 % of them being indigenous. Residential areas were dominated by exotic trees, mainly due to the abundance of exotic fruit trees like Mangifera indica. Generally, the city has a good tree diversity score but unequally distributed, with the formal residential areas, where the colonial masters settled, having more trees than the mixed and informal residential areas. Nine urban greenspace types were identified, but there was a low per capita urban greenspace area of 11.6 m2 per person, slightly above the minimum standard set by World Health Organisation. From the preferences for and perceptions of urban greenspaces, patronage to these greenspaces (treated as parks) was highest among the educated youth, a majority being from the high housing density areas where there are no urban parks. Walking to the nearest urban greenspace took more than 10 minutes for 85 % of the respondents. With the available by-laws in support for the governance of greenspaces within the city and the role of residents towards the same, restoration efforts that targeted Sadzi hill yielded positive results through reversing ecosystem disservices that were being experienced by the community members around the hill. The community enjoys several ecosystem services that have also contributed towards building their resilience to climatic and environmental hazards. The results of this study have unveiled several green infrastructure attributes that can contribute towards building urban social ecological resilience like the presence of high proportion of indigenous tree species, healthy urban forest, high proportion of fruit trees, high diversity scores, unparalleled demand for urban greenspaces for cultural and regulatory ecosystem services, the willingness to pay and work towards managing and conserving greenspaces and the social capital available from the urban communities. However, the study also unveiled several green infrastructure related attributes that if not checked will continue to undermine efforts towards building urban resilience. These included the continued drop in tree and greenspace cover, poor governance of the available public greenspaces, unequal distribution of trees and urban greenspaces, poor management of greenspaces, bare river banks, lack of park amenities and a lack of a clear strategy, policy or an urban plan that clearly outlines green infrastructure. Efforts towards addressing these will mean acknowledging the role of green infrastructure in supporting urban social ecological resilience. , Thesis (PhD) -- Faculty of Science, Environmental Science, 2023
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- Date Issued: 2023-10-13
Stimulating continuous professional development and teacher leadership in a rural Namibian school: a participatory action research
- Authors: Mario, Kangende Mebin
- Date: 2023-10-13
- Subjects: Uncatalogued
- Language: English
- Type: Academic theses , Master's theses , text
- Identifier: http://hdl.handle.net/10962/424075 , vital:72121
- Description: Namibia values democratic and quality education. One way to improve quality education is by allowing teachers autonomy and offering continuous professional development (CPD) to teachers. Historically, the CPD programmes on offer in Namibia were centralised and generic, using a ‘one-size-fits-all’ approach offered as mini workshops to train teachers. In 2012, a decentralised method of school-based CPD program was initiated in schools, to give opportunities to schools to identify, plan, implement and evaluate their own professional needs. However, a recent study indicated that these initiatives have failed due to poor leadership, a lack of training and support as well as limited knowledge of principals in running CPD initiatives. Against this backdrop, my study aimed at engaging in a participatory action research process with teachers and SMT members in a rural combined school in the Kavango West region to stimulate the failed school-based CPD program and develop teacher leadership. My study therefore aligned with the international recommendations that school-based CPD be built around the notions of distributed leadership and teacher leadership (Smulyan, 2016; Hunzicker, 2018). The three-step model of change and action research developed by Kurt Lewin served as the underpinning theory for this study. The study was situated within a critical paradigm and driven by the question: “Does the involvement in participatory action research process stimulate a school-based CPD programme and develop teacher leadership?” The study involved two phases. The contextual profiling stage generated data through the analysis of documents, focus group interviews, and observation. Phase 2 engaged the participant in participatory action research to stimulate school-based CPD and develop teacher leadership. Thematic analysis supported by both inductive and deductive methods was used to analyse the data. The findings from phase one indicated that CPD was interpreted differently by the participants and confirmed that there was no CPD program in the school. Using Grant's (2017) model of teacher leadership, the findings further revealed that although teacher leadership was practised in all four zones, it was strongest in the classroom and initiated through delegated practices. Using Angelle and Dehart (2010), constraining forces included negative teachers’ attitudes, limited knowledge, skills, and confidence as well as a school culture of distrust. Phase 2 revealed that participatory action research can be a useful stimulus for school-based CPD. A tangible output from the PAR sessions was a template for the internal policy for school-based continuous teacher development. In addition, the findings from the sessions indicated the significance of supportive leadership to ensure the efficacy of school-based CPD and teacher leadership. , Thesis (MEd) -- Faculty of Education, Primary and Early Childhood Education, 2023
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- Date Issued: 2023-10-13