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Item Climate change and heritage tourism: threats to Makgabeng in a regional context, Limpopo South Africa(2020-11) Mcpherson, Fazlin AhdielahThe Makgabeng area is situated in the north-west corner of the Limpopo province in South Africa. The Makgabeng area is an emerging tourist destination with a variety of activities to offer. The area is rich in ancient rock art sites and, as a result, has great potential for the development of heritage tourism. Extensive research has been conducted on the rock art in this region. However, the impact of climate change on heritage tourism has not yet been explored. The local community of the Makgabeng area is developing a heritage tourism destination within the region and it is important to determine whether the initiative will be sustainable, especially in the context of climate change threats to the region. In a region such as Makgabeng where the primary attraction is natural heritage tourism rather than cultural, this then poses a severe threat to tourism within the region, especially since most of these attractions are outdoors. Hence, this research project is primarily aimed at determining climate change threats to heritage tourism in the Makgabeng region, South Africa. The research has employed a mixed-method approach consisting of interviews done with various stakeholders within the tourism industry and community members in the Makgabeng region. The other methods used are hard-copy and online questionnaires, TripAdvisor reviews, and the Tourism Climatic Index (TCI). What the research has found is that people do not know that Makgabeng exists, and for those who are aware of its existence they have never visited the region. this is because the area is not being marketed effectively. The TCI scores show that winter is the best time of the year for tourism. Consequently, stakeholders and community members should market the area with this in mind. However, tourists have said they enjoy the weather in the region all year round.Item A comparative analysis of classic Geometrical methods and sparse regression methods for linearly unmixing hyperspectral image data(2019) Nicolae, AurelThis research report presents an across-the-board comparative analysis on algorithms for linearly unmixing hyperspectral image data cubes. Convex geometry based endmember extraction algorithms (EEAs) such as the pixel purity index (PPI) algorithm and N-FINDR have been commonly used to derive the material spectral signatures called endmembers from the hyperspectral images. The estimation of their corresponding fractional abundances is done by solving the related inverse problem in a least squares sense. Semi-supervised sparse regression algorithms such as orthogonal matching pursuit (OMP) and sparse unmixing algorithm via variable splitting and augmented Lagrangian (SUnSAL) bypass the endmember extraction process by employing widely available spectral libraries a priori, automatically returning the fractional abundances and sparsity estimates. The main contribution of this work is to serve as a rich resource on hyperspectral image unmixing, providing end-to-end evaluation of a wide variety of algorithms using di erent arti cial data sets.Item Comparing the effectiveness of LSTM, ARIMA, and GRU algorithms for forecasting customer charging behavior in the electric mobility industry in Europe(University of the Witwatersrand, Johannesburg, 2023) Pelwan, Robyne ChimereForecasting, a powerful technique for unveiling potential future events, relies on historical data and methodological approaches to provide valuable insights. This dissertation delves into the domain of electric mobility, investigating the effectiveness of three distinct algorithms—Long Short-term Memory (LSTM), Autoregressive Integrated Moving Average (ARIMA), and Gated Recurrent Unit (GRU)—for predicting customer charging behavior. Specifically, it focuses on forecasting the number of charges over a 7-day period using time-series data from European electric mobility customers. In this study, we scrutinize the interplay between algorithmic performance and the intricacies of the dataset. Root mean squared error (RMSE) serves as a metric for gauging predictive accuracy. The findings highlight the supremacy of the ARIMA model in single-variable analysis, surpassing the predictive capabilities of both LSTM and GRU models. Even when additional features are introduced to enhance LSTM and GRU predictions, the superiority of ARIMA remains pronounced. Notably, this research underscores that ARIMA is particularly well-suited for time series data of this nature due to its tailored design. It contributes valuable insights for both researchers and practitioners in the electric mobility industry, aiding in the strategic selection of forecasting methodologies.Item Enumeration of binary strings and applications to compositions and partitions(University of the Witwatersrand, Johannesburg, 2023) Raphadu, MalekaIn this dissertation we first introduce binary strings and give a historical background. Then we discus some techniques for enumerating restricted sets of binary strings ,with several example . We employ mainly the symbolic method and recursive techniques, among others, to obtain our results. A chapter is devoted to a discussion of some published case studies on bit string enumerations which are relevant to our project. Then we consider how the study of binary string may facilitate the enumeration of selected classes of compositions and integer partitions.Item Estimating skills in discrete pursuit-evasion games(University of the Witwatersrand, Johannesburg, 2023) Gomes, Byron John; Rosman, BenjaminGame Theory is a well-established field in mathematics, economics, and computer science, with a rich history of studying n-person, zero-sum games. Researchers have utilized the best computational power of their time to create computational players that are able to beat the best human players at complex two-player, zero-sum games such as Chess and Go. In the field of Reinforcement Learning and Robotics, these types of games are considered useful environments to conduct experiments about agent behavior and learning. In this research report we explore a subset of discrete skill-dependent pursuit-evasion games upon which we build a framework to estimate player skills. In this game environment a player’s skill determines the actions available to them in each state and the transition dynamics resulting from the chosen action. The game offers a simplified depresentation of more complex games which often have vast state and action spaces, making it difficult to model and analyze player behavior. In this game environment we find that players with incorrect assumptions about an opponent’s skill perform sub-optimally at winning games. Given that knowledge of an opponent’s skill impacts on player performance, we demonstrate that players can use Bayesian inference to estimate their opponent’s skill, based on the action outcomes of an opponent. We also demonstrate that skill estimation is a valuable exercise for players to undertake and show that the performance of players that estimate their opponent’s skill converges to the performance of players given perfect knowledge of their opponent’s skill. This research contributes to our understanding of Bayesian skill estimation in skill-dependent pursuit-evasion games which may be useful in the fields of Multi-agent Reinforcement Learning and Robotics.Item Fabrication of polyaniline/indium oxide /onion-like carbon ternary nanocomposite for room tempera ture gas sensing applications(University of the Witwatersrand, Johannesburg, 2022-08) Mathe, Boipelo Nicholette; Linganiso, E.C; Tetana, Z; Moma, JMonitoring and documenting chemical stimuli or environmental fluctuations is vital to daily health care and environmental monitoring. This objective can be accomplished through the development of high-performance sensors able to detect toxic gases such as ammonia, volatile organic compounds (VOCs) and many more. The modification of carbon nano-onions with metal oxides/conducting polymer could enhance sensing performances at room temperature. This research focuses on the development of a flexible room temperature gas sensor for ammonia sensing with a sensing layer composed of indium oxide (In2O3)/onion-like carbons (OLCs)/ polyaniline (PANI). The current sensors were tested at a 40-45 percentage humidity. Polyaniline was produced utilizing the rapid polymerization technique with aniline and ammonium persulfate as precursors. Carbon nano-onions were obtained by the flame pyrolysis process with candle wax as the carbon source. The present study compared two microwave-assisted solution-phase methods for the synthesis of indium oxides. The first methods produced indium hydroxide (In(OH)3) followed by its conversion to In2O3 through annealing at 400 oC, and the second used a one-step method where ethanol was used as a solvent instead of water. Different reaction times were used to determine the effect of microwave power on the indium oxide formed through a solution-phase method, and several characterizations techniques were performed to characterize the products, including transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, Brunauer-Emmett-Teller, X-ray photoelectron spectroscopy and Ultraviolet-visible spectroscopy. The ternary In2O3/PANI/OLCs nanocomposite was fabricated using physical mixing by adding varying amounts of In2O3 to fixed quantities of PANI and OLCs. Using gold-plated interdigitated electrodes (IDEs) embedded on a printed circuit board (PCB) substrate, inexpensive and room temperature functional sensors based on plain PANI, OLCs, OLCs/PANI, and OLCs/PANI/In2O3 were developed. The sensors based on ternary composites outperformed of sensors based on pure PANI, OLCs, and PANI/OLCs, due synergic effect of PANI, OLCs and In2O3 when combined. The sensor with the highest response among the sensors with the ternary nanocomposite as the sensing layer, was chosen for further evaluations of recovery time, reaction time, repeatability, and selectivity. The sensor containing (4.6 mg) B-In2O3/PANI/OLCs was particularly responsive to ammonia in comparison to other analytes (hexane, isopropanol, acetone), with the response and recovery durations of 2.2 minutes and 4.3 minutes, respectively, spanning a concentration range of 25 ppm to 125 ppm. Current results showed that In2O3 materials can be successfully applied in room temperature gas sensing application and further enhance the sensing response to levels that cannot be obtained when using PANI or OLC individually.Item Functional feeding groups of mayfly nymphs (Ephemeroptera) in South African rivers of the North West and Limpopo Provinces(University of the Witwatersrand, Johannesburg, 2024-02) Bossman, Esi H.; Harrison, James du G.; Woodford, Darragh J.Researchers, primarily in the Northern hemisphere, have extensively studied mouthpart morphology and dietary variability in Ephemeroptera (colloquially called mayflies). Ephemeroptera are key primary consumers in rivers around the world and are used as aquatic biomonitoring indicators due to interspecific variation in ecological tolerances that make them good indicator taxa. Cummins (1973, 1974) created a functional feeding groups (FFG) classification system, based on northern hemisphere macroinvertebrates, as a universal tool to functionally categorise organisms based on their primary feeding mode within their habitat. The FFG classification system is useful in identifying interrelations between structural and functional components of an ecosystem. The aim of this study was to contribute knowledge on FFGs for particular mayfly species, in the southern African savanna biome, through mouthpart morphology and gut content analysis. Four study sites were sampled from the Magaliesberg (M) and Waterberg (W) catchments. There were three species studied, namely Afroptilum parvum (Family Baetidae), Afronurus barnardi (Family Heptageniidae) and Elassoneuria sp. (Family Oligoneuriidae). These species’ mouthparts were dissected and their macro- and microstructures were prepared for viewing with Scanning Electron Microscopy (SEM) and light microscopy. Micrographs and images showed variation in mouthpart morphology between all three species, with special attention to the labia and maxilla microstructures. The identification and description of microstructures that differentiate mayfly species (and the adaptations of these appendages to facilitate food uptake and ingestion) are important to address knowledge gaps regarding mayfly mouthpart morphology. A Principal Component Analysis (PCA) showed distinct grouping of the three species, with mandibles and maxillary palps showing the most variation between species. After analysis, the following feeding groups were assigned: Afroptilum parvum is a collector-gatherer feeder, Afronurus barnardi is a brusher-scraper feeder and Elassoneuria sp. is a filter feeder. This study showed, in part, that the Cummins’ (1973, 1974) classification categories were too broad for classifying organisms from a South African savanna stream. However, it is a good foundational starting point for region specific FFG classification systems. Thus, it is recommended to use the classification system Cummins created as a starting point for classifying organisms into FFGs with an initial definition that can be expanded upon to create individual classification systems for different localities.Item Investigating the regulation of PXDN expression by the early growth response 1(EGR1) transcription factor in the context of human fibrotic diseases(University of the Witwatersrand, Johannesburg, 2023) Makhanya, ThokozilePeroxidasin (PXDN) is a novel member of the peroxidase-cyclooxygenase family of haem containing proteins that catalyze oxidative reactions. It consolidates the extracellular matrix (ECM) by using hydrogen peroxide (H2O2) as a substrate to generate hypohalous acid intermediates, which help catalyze the formation of sulfilimine bonds between collagen IV protomers. The aberrant expression of PXDN has been linked to the development of various diseases where the architecture of the ECM is compromised such as cardiovascular diseases, ocular diseases, cancer, and fibrosis. Fibrosis develops due to repetitive tissue injury which is followed by aberrant wound healing that causes the excessive deposition of ECM proteins such as collagen into the injured tissue. In turn, ECM crosslinking enzymes such as PXDN are upregulated, and the matrix becomes thick and heavily crosslinked. This study aims to elucidate whether early growth response 1 (EGR1), a zinc-finger transcription factor which regulates cell proliferation, differentiation, apoptosis, and a key pro-fibrotic protein, can drive PXDN expression. To address the aim, HEK293 cells were treated with TGF-β1, a master activator of fibrotic genes, and western blot and immunofluorescence microscopy were performed to detect EGR1 and PXDN and their cellular localization, respectively. Chromatin immunoprecipitation (ChIP) was performed to determine if EGR1 binds to the PXDN promoter and the luciferase reporter assay was employed to determine if the interaction resulted in an alteration in gene expression. Our western blot findings showed that for EGR1, there was a statistically insignificant increase in protein expression in response to the TGF-β1 treatment. PXDN expression could not be quantified due to the high background on the blots. Further analysis by immunofluorescence microscopy showed that EGR1 expression was increased and was localised to the nuclei in response to the TGF-β1 treatment. We also observed that PXDN was predominantly expressed extracellularly and showed a significant increase in protein expression with treatment. The bioinformatics analysis has identified two putative EGR1 binding sites in the PXDN promoter and ChIP-PCR showed that binding occurred at one of these sites. This site was cloned into the pGL4.10 vector to determine whether EGR1 drives PXDN expression. Due to unsuccessful transfection optimization, the luciferase assay could not be performed and therefore for future work this assay needs to be performed to verify if EGR1 can drive PXDN expression. In conclusion, we showed that PXDN is a TGF-β1-responsive gene and may be regulated by EGR1. Studying the interaction of EGR1 and PXDN may establish roles for PXDN in fibrosis and further consolidate PXDN as a possible anti-fibrotic therapeutic target.Item On polarity-based semantics for non-distributive modal logics(University of the Witwatersrand, Johannesburg, 2023) Clingman, R.; Conradie, WillemThis masters study builds upon recent research in polarity-based semantics for non-distributive modal logics (NDMLs). Current formulations of polarity-based semantics for NDML impose compatibility requirements on additional relations of polarity-based frames, hindering applicability of the semantics, as arbitrary frames need not be compatible. In this study we develop a polarity-based semantics for NDML with modalites that are, in general, neither normal nor distributive and without the imposition of compatibility requirements. We provide a sound and complete axiomatization of this logic. The second half of the thesis focuses on a special class of enriched polarities, those who are in a sense liftings of Kripke frames. The compatibility of these liftings combined with the intuitive nature of the underlying Kripke frames makes for a useful case study in which to explore p-morphisms between enriched polarities, and enriched polarity-based models, from a relational perspective.Item Resolvability of groups(University of the Witwatersrand, Johannesburg, 2020) Ndhlalane, MororisengA topological group is called resolvable if it can be partitioned into two dense subsets. A group is absolutely resolvable if it can be partitioned into two subsets dense in any nondescript group topology. The aim of this dissertation is to give a unified exposition of some major results about resolvability of groups. In particular, we show that; 1. Every countable nondescript topological group not containing an open Boolean subgroup is resolvable, 2. Every infinite Abelian group not containing an infinite Boolean subgroup is absolutely resolvable.Item The genome sequence of the Yellow-billed Duck (Anas undulata)(University of the Witwatersrand, Johannesburg, 2024-01) Ngxamani, Namhla; De Maayer, Pieter; Mollett, JeanNo abstract givenItem The influence of plant phenolic compounds on the host range of Coniatus tamarisci Fabr. (Coleoptera: Curculionidae): a potential biological control agent of invasive Tamarix L. (Caryophyllales: Tamaricaceae) Taxa in South Africa(University of the Witwatersrand, Johannesburg, 2022) Hatile, Sivenathi Luvolwethu; Byrne, Marcus; Mayonde, SamalesuTamarix L. (Caryophyllales: Tamaricaceae) are halophyte species that are native to Eurasia, North Africa, and southwestern Africa. These phreatophyte trees or shrubs have become prominent and widespread invaders in North America, South America, Australia, and South Africa. In South Africa, the Alien and Invasive Species regulations of the National Environmental Management: Biodiversity Act 2014 (NEM:BA) has classified invasive Tamarix as category 1b invader, which require control. Thus, three potential biological control agents have undergone laboratory-based host-specificity trials for the long-term sustainable control of Tamarix. The first two of these biocontrol agents, Diorhabda carinulata (Desbrochers.) (Coleoptera: Chrysomelidae) and Trabutina mannipara (Hemprich & Ehrenberg) (Hemiptera: Pseudococcidae), both failed the laboratory-based host-specificity trials because they completed their life cycle on the indigenous T. usneoides E. Mey ex Bunge. Previously, potential biocontrol agents were selected based on their native distribution and the phylogenetic relatedness of the invasive weed to indigenous nontarget species. However, it has recently been suggested that secondary metabolites also play a major role in insect host selection, and thus should be considered to improve the selection criteria of potential biocontrol agents. The current study is based on the third biocontrol agent that recently underwent laboratory based host-specificity trials in South Africa, Coniatus tamarisci (Fabr.) (Coleoptera: Curculionidae). This was in conjunction with an analysis of the potential influence Tamarix phenolic compounds have on insect host selection. The results show that although C. tamarisci could complete its’ life cycle on T. usneoides, the weevil had a low affiliation/risk associated with the indigenous Tamarix taxon. This advocates for the conduction of open field host-specificity trials, which will allow for a better understanding of C. tamarisci behaviour in a natural setting. Regarding phenolic compounds, three phenolic acids have been identified as being significantly prominent in T. usneoides compared to the invasive Tamarix taxa present in South Africa. These are gallic acid, dehydrodigallic acid, and syringic acid. These compounds are associated with protection from plant herbivory, which could explain the behaviour of C. tamarisci when exposed to and reared on T. usneoides.Item The role of place names as indegenous knowledge in the archeology of the Makgabeng-Blouberg area, South Africa(University of the Witwatersrand, Johannesburg, 2024) Vena, Kgolagano; Namono, CatherineThe act of naming places has a twofold process of significance, firstly, it acts a locator of a particular geographical place and secondly reveals the ideology of the place that gives it its legitimacy. As such, place names represent one of the oldest forms of human cultural heritage. Place names are tailored for encrypting heritage and indigenous knowledge. However, in areas that have had significant interaction with external naming regimes, the indigenous naming processes have been suppressed. The Makgabeng-Blouberg area cultural landscape has an exceedingly long and interactive process with colonial naming processes. This research analyses the socio-political processes that shaped the prevalence of colonial place names in the Makgabeng-Blouberg area and significance of indigenous toponyms to the community. The study suggests that colonial power had far reaching effects in the region. The prevalence of colonial names is a result of subsequent naming regimes continuing the hegemonic ideological dominance over places to reflect their control. However, these indigenous communities, navigate this subjugation through engaging in alternative naming systems. Indigenous place names are used by these communities to preserve their culture and heritage. As such, these place names became part of the community's sense of identity and their historical value, thus creating generational ties and anthropological places for the community.