List of Titles

Chemostratigraphy of the lowermost iron-manganese cycle of the Hotazel Formation, and implications for its primary depositional environment

- Masoabi, Ntseka Thomas

Authors: Masoabi, Ntseka Thomas
Date: 2022-10-14
Subjects: Chemostratigraphy , Great Oxygenation Event , Manganese ores Geology South Africa Northern Cape , Banded iron formation
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/362938 , vital:65376
Description: The giant Kalahari Manganese Field (KMF), located in the Northern Cape Province, South Africa, comprises approximately half of the world’s manganese resources, estimated at about eight billion tons at grades ranging from 20-48 wt%. The KMF is linked to a period in geological time when the Earth’s atmospheric and oceanic conditions underwent a major transition from oxygen-deficient to oxygen-enriched conditions – an event famously referred to as the Great Oxidation Event (GOE) that occurred around 2.4 Ga. The KMF deposits are hosted in Banded Iron Formation (BIF) of the Paleoproterozoic Hotazel Formation in the uppermost Transvaal Supergroup. The sedimentary Mn ores are interbedded with Hotazel BIF in the form of three alternating depositional cycles of BIF, transitional hematite lutite and laminated, carbonate-rich manganese ore. The lowermost and thickest of the three cycles is the most economically significant and has been mined for several decades on a large scale from the southernmost KMF. In this study, two drill cores from the southern KMF were inspected, logged and sampled at a high resolution of approximately half-meter interval per sample. The selected cores, namely G774, capturing the lower portion of the Hotazel Formation from the Mamatwan locality, and MP-56, capturing the corresponding portion from the Middleplaats locality, are geographically proximal to each other, with a horizontal distance of roughly 3 km separating the two of them. The G774 drill core is characterized by a conspicuously thick manganese layer covering a thickness of 50 m, with the overlying BIF reaching a total thickness of 11 m. The MP-56 drill core, on the other hand, has a relatively thinner corresponding manganese layer of 30 m in thickness, while the overlying BIF layer exhibits a thickness of 24 m. The extent of sampling up-section was constrained by an apparently coeval black shale layer which represents the chosen upper stratigraphic marker for the lower part of the Hotazel section in the broader area that is under investigation in this thesis. That way, a high resolution chemostratigraphic approach was employed to elucidate the potential factors contributing to the relative sedimentary lateral thickness variations seen across the southernmost KMF. High-resolution geochemical data were used to explore relationships and signals that might constrain relative precipitation rates for iron and manganese against detrital species, fluctuating redox conditions in the original environment of deposition, and chemostratigraphic correlation. All geochemical data (i.e., major oxides, minor and trace elements and carbonate carbon isotopes) were obtained respectively through employing X-ray Fluorescence (XRF), Laser Ablation Inductively Coupled Mass Spectrometry (ICP-MS), and Gas-source mass spectrometry. Comparative considerations made between the bulk geochemistry of the two sequences (i.e., Mamatwan and Middleplaats sections) reveal that periods of high-Mn deposition in the Hotazel Formation appear to be very Ca-carbonate rich (as indicated by high CaO, LOI and Sr concentrations). This, in turn, suggests that the Mn abundance is in the Hotazel ores is controlled mainly by the silicate phase braunite and is diluted by the deposition of Ca-carbonate through time. Bulk-rock concentration results for trace elements of the High Field Strength Element (HFSE) group (namely Zr, Hf, Y, Nb and Sc) were utilized to constrain the rates of either clastic and/or volcanic detrital inputs, as they traditionally represent refractory mineral particles of a common detrital/volcanic origin. The two chemosedimentary sequences preserve these elements in very low and thus quantitatively negligible concentrations – suggesting that the Hotazel depositional environment received very low and insignificant influx of a terrigeneous detrital component. A selection of these elements was therefore used to deduce, with caution, the relative as opposed to absolute precipitation rate of the major chemical constituents (i.e., Fe + Si vs Mn + carbonate), assuming a constant detrital flux through time. It was found that the relative abundances of Zr, Y and Nb is roughly 1.5 – 2 times as high in the BIF lithofacies relative to the Mn ones at both localities. This led to the inference that the Mn-enriched portion of the sediment must have been deposited at approximately twice the rate that the Fe-rich (BIF) portion was originally deposited. In terms of redox-sensitive elements, the elements Co and Mo seem to reveal the most valuable insights into the redox environment of primary chemical deposition. Cobalt displays a unique pattern in that its highest concentration is attained at the hematite lutite transitions (similarly with the REE in this regard), while very low and seemingly invariant concentration is exhibited within the core of the main orebodies. The same pattern seems to be reproduced to a degree by the corresponding bulk MgO component, whereby MgO abundance maxima are associated with the basal hematite lutite and the hematitic flanks of the Mn-ore zone, while the core of the Mn-rich layer attains relatively low and essentially invariant MgO concentrations. This implicates a close and direct association of Co with the hematite fraction of the rocks and a concurrent enrichment in Mn-rich carbonate (dolomite). On the other hand, Mo seems to have a direct and clear association with peak MnO2 content of the rocks, which in turn presents a high possibility of Mo having adsorbed onto primary Mn-oxyhydroxides in the water column, thus providing evidence that Mn-oxide must have acted as an important Mo sink, at least locally. Finally, the carbonate-carbon isotope results provide a useful tool that brings the two stratigraphic sections “together“, in conjunction with other correlatable chemostratigraphic parameters (e.g. Co, Mg). The results demonstrate that bulk carbon fluxes and isotopic signals in the sediments must reflect primary processes of deposition, and that correlation across two apparently disparate lithostratigraphic sections can be effected. The key finding is that, at times, manganese deposition in one part of a vii stratified basin was evidently accompanied by simultaneous BIF deposition at another, thus painting a very complex picture of massive primary chemical precipitation of Fe and Mn at the dawn of the GOE. , Thesis (MSc) -- Faculty of Science, Geology, 2022
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Date Issued: 2022-10-14

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The use of smartphones and visualisation processes for conceptual understanding of mensuration: a case study of the Mathcitymap Project in Namibia

- Shimakeleni, Liina

Authors: Shimakeleni, Liina
Date: 2022-04-08
Subjects: Mathematics Study and teaching (Secondary) Namibia Oshana , Smartphones , Visual learning , Measurement , Concept learning , ‎MathCityMap (MCM) project
Language: English
Type: Academic theses , Master's theses , text
Identifier: http://hdl.handle.net/10962/290649 , vital:56771
Description: The aim of this study was to investigate and analyse the potential use of smartphones as visualisation tools by learners to enhance conceptual understanding through mathematics trails developed using the MathCityMap (MCM) project. This research study is part of the VIPROmaths project which seeks to research the effective use of visualisation processes in mathematics classrooms in South Africa, Namibia, Zambia, Switzerland and Germany. This study adopted a case of twelve purposively selected Grade 9 learners from a school in the Eheke circuit of the Oshana region, Namibia. This study was framed within a social constructivist perspective and sought to investigate visualisation processes as well as conceptual understanding of learners as they conceptualised the MCM tasks in new, outdoor and collaborative learning situations. The MCM app was installed on selected learners’ smartphones to access and to walk the MCM trails located in various places in the schoolyard. Three MCM trails based on three key themes of mensuration (perimeter, area and volume) were created. Each consisted of four tasks that were sourced and developed in line with the Grade 9 Namibian mathematics syllabus. This study is oriented in an interpretive paradigm and employed video-recorded observations and focus group interviews as qualitative data collection methods. Data collected were analysed first using the themes developed from Ho’s (2010) work on visualisation processes and Kilpatrick, Swafford, and Findell’s (2001) conceptual understanding. During analysis, some themes emerged from the data and were considered. Findings from this study revealed that smartphones afforded learners ample opportunities to enhance the visualisation processes that they went through as they learned the concepts of measurement. In addition to this, some learners were initially pessimistic regarding the use of smartphones for learning purposes. This study recommends that resources such as MCM be effectively be used in formal school settings. The learning of measurement can be advanced in outdoor settings where learners have physical and spatial access to the learning content. Smartphone technology can be used as an additional tool to integrate Information and Communication Technology (ICT) in learning mathematics within the Namibian context. , Thesis (MED) -- Faculty of Education, Education, 2022
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Date Issued: 2022-04-08

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Exploring the effect of the indigenous technology of oil extraction on Grade 10 Biology learners’ perspectives and sense making of enzymes

- Nyamakuti, Martha Ndeyatila

Authors: Nyamakuti, Martha Ndeyatila
Date: 2021-10-29
Subjects: Biology Study and teaching (Secondary) , Enzymes , Traditional ecological knowledge Namibia , Culturally relevant pedagogy Namibia , Reasoning , Contiguity Argumentation Theory (CAT) , Namibian National Curriculum for Basic Education(NCBE) , Socio-cultural theory
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/192019 , vital:45188
Description: The current status quo is that African learners’ local indigenous knowledge (IK) and experiences from home (cultural heritage) are not considered in science classrooms. In the context of Namibia, it seems that the Namibian curriculum policies do little or nothing to decolonise and address the issues of equity and social injustice in Namibian schools. For instance, although the Namibian National Curriculum for Basic Education (NCBE) claims that it “embraces traditional knowledge”, it does not specify how this should be done in schools. As a result, little or no integration of IK is enacted in many of our schools in Namibia. Resultantly, learners seem to find science inaccessible and irrelevant to their everyday lives. It is against this background that in this study I sought to explore how the mobilisation of the indigenous technology of oil extraction (okuyenga) from marula nuts and melon seeds influences (or not) Grade 10 Biology learners’ conceptions, dispositions and sense making of the topic of enzymes. The study was located within the interpretive and indigenous research paradigms. Central to the interpretive paradigm is the development of a greater understanding of how people make sense of the contexts in which they live and work. On the other hand, central to indigenous research paradigms are belief systems based on the lived experiences, values, and histories of the participants. The Ubuntu perspective or approach in which respect and humble togetherness is emphasised is critical in indigenous research paradigms especially when researchers are working with and in communities as I did in this study. The study was conducted in an under resourced school in Walvis Bay, Namibia. A qualitative case study approach was used and data were derived from a focus group interview, participatory classroom observations, learners’ reflections, and a stimulated recall interview. Vygotsky’s socio-cultural theory was employed as a theoretical framework. Within the socio-cultural theory, mediation of learning, social interactions, and the zone of proximal development (ZPD) were used as analytical lenses. The conceptual framework comprised of perspectives (conceptions, dispositions) and sense making of enzymes by the learners. Criteria were also adapted from Atallah, Bryant, and Dada to analyse learners’ perspectives. A thematic approach to analysis was employed to come up with categories and sub-themes and thereafter, common sub-themes were combined to form themes. The findings of the study revealed that the presentations on the indigenous technology of oil extraction by the expert community members influenced learners’ conceptions, dispositions, and sense making of enzymes and other associated science concepts. This was noticed when learners extracted emerging science concepts from the indigenous technology of oil extraction. The implication of this study is that there is a need for science teachers to consider learners’ cultural heritage and integrate local IK in their Biology classrooms in order to make science accessible and relevant to learners. Moreover, the integration of local IK is critical for learners to embrace and respect their cultural heritage. This study thus recommends that teachers should make efforts to collaborate with expert community members who are the custodians of local IK and tap into their cultural heritage and wisdom to enrich teaching in their science classrooms. , Thesis (MEd) -- Faculty of Education, Education, 2021
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Date Issued: 2021-10-29

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What are the pertinent intersections in the lives of black women at Rhodes University?

- Gushman, Lutho Phinda

Authors: Gushman, Lutho Phinda
Date: 2021-10-29
Subjects: Women, Black South Africa Makhanda , Student movements South Africa Makhanda , Intersectionality (Sociology) , Pluralism , Matrix organization South Africa Makhanda , Women, Black Education (Higher) South Africa Makhanda , Social action South Africa Makhanda , Rhodes University
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/190990 , vital:45047
Description: After the 2016 #FeesMustFall protest(s), higher education institutions were dramatically altered with respect to their institutional cultures; the narratives of those who were historically side-lined and marginalised took centre stage. At Rhodes University social activism was constitutive of three components; a ‘revolt’ against the fee increment; a contestation of the rape culture; and a rejection of the colonial curriculum. These concerns, in their varied articulations, made up different social and academic realities that define(d) Rhodes University and affected how individuals experienced institutional culture. According to Ndlovu (2017) while these expressed acts (in the form of protests and institutional shutdowns) of resistance against the system of higher education subsided after the fees must fall campaign, these served to centre the narratives of the marginalised. Keeping with this thinking, the argument presented in this thesis explores the experiences of black women in higher education after the call towards coordinated resistance. Using qualitative data in the form of narrative interviews, the thesis documents how the participants continued their academic and social life post-resistance. This rupture of resistance created a complex matrix of individual subjectivity where participants engaged with traditional social academic norms in new spaces of resistance; a phenomenon that enlivened the intersectionality that came to define the higher education landscape of the country. This thesis explores the stories of the participant’s as they engage(d) with what is becoming a new institution—that is the University in South Africa, with a case-in-point being Rhodes University—and to understand the power relations and intersections that define their lived experiences. This study found that the reality of existing within the confines of power—with its fluidity—meant that black women operate both within spaces of privilege and oppression simultaneously. As such, and following Vivian May’s (2015) argument, this study concludes that black women are situated and simultaneously constrained by power. Thus spaces of resistance are constantly in flux and determined by their relations within power. , Thesis (MA) -- Faculty of Humanities, Politics and International Studies, 2021
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Date Issued: 2021-10-29

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Larval fish dynamics within the coastal nearshore of the Eastern Cape, South Africa

- Sotshongaye, Oko

Authors: Sotshongaye, Oko
Date: 2021-04
Subjects: Fishes -- Larvae -- South Africa -- Eastern Cape , Fishes -- Larvae -- Development -- South Africa -- Eastern Cape , Fishes -- Larvae -- Ecology -- South Africa -- Eastern Cape , Coastal ecology -- South Africa -- Eastern Cape , Fishes -- Larvae -- Dispersal -- South Africa -- Eastern Cape
Language: English
Type: thesis , text , Masters , MSc
Identifier: http://hdl.handle.net/10962/176977 , vital:42776
Description: The coastal nearshore is important for the early development of fishes as it is used for spawning and/or as a nursery. One of the central concerns in coastal ecology is understanding the role of the nearshore for larvae, ultimately providing key knowledge on population dynamics and hence helping in making decisions pertaining to conservation and resource management. The aim of this study was to investigate the alongshore and cross-shore distribution of larval fishes and the links to the physio-chemical conditions (including prevailing winds) and hydrodynamics in the region of Algoa Bay, situated on the south east coast in the warm temperate region of South Africa. Fish larvae were sampled at nine sites for the first component of the study (January 2016 –March 2017) and at four sites for the second component (November 2019), near the surface and bottom (15-50 m) of the water column as well as at two different distances from shore (~400 m/~3 km) using a set of bongo plankton nets towed behind a boat. Environmental data were simultaneously collected using and acoustic Doppler current profiler (ADCP) and conductivity, temperature, depth (CTD) profiler. Larval fish abundance generally decreased with increasing distance from the shore, however, this varied in space and time, with some larval species recorded in high abundances offshore. Close inshore the larvae of coastal fish species producing benthic eggs (CBE) including the Blenniidae and Gobiesocidae mostly dominated, while offshore the larvae of coastal fish species producing pelagic eggs (CPE) i.e. Sparidae and Cynoglossidae, as well as pelagic fish species producing pelagic eggs (PPE) i.e. Clupeidae and Engraulidae mostly dominated. Vertical distribution of larvae differed according to taxon, with the Callionymidae (CPE), Cynoglossidae and Gobiesocidae occurring at high densities at the bottom of the water column, while the Blenniidae dominated near the surface. Fluorescence, temperature and salinity varied with depth (surface/bottom), being particularly high at the surface; currents moved faster at the surface than the bottom of the water column. Increased abundances of larval fishes were evident after upwelling events (associated with easterly winds) in the Bay, while during downwelling (associated with westerly winds), low densities were generally recorded, except for the sites situated near headlands/capes where there were higher densities of fish larvae during downwelling events. Overall, the results of this study suggest that spawning mode of the adults, oceanography and environmental conditions coupled with what is known of the behaviour of fish larvae, were important in shaping the larval fish community of the Algoa Bay region. These results highlight the importance of incorporating multiple biological (developmental stage, reproductive mode, species) and physical (currents, fluorescence, wind-driven up/down-welling) factors when addressing the mechanims of transport of larval fish in the coastal nearshore. , Thesis (MSc) -- Faculty of Science, Department of Zoology and Entomology, 2021
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Date Issued: 2021-04

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The effects of extracellular and intracellular Hop on cell migration processes

- Contu, Lara

Authors: Contu, Lara
Date: 2014
Subjects: Heat shock proteins , Metastasis , Cancer Chemotherapy , Molecular chaperones , Cell migration
Language: English
Type: Master's theses , text
Identifier: http://hdl.handle.net/10962/193961 , vital:45410
Description: The Hsp70/Hsp90-organising protein (Hop) is a 60 kDa co-chaperone that acts as an adaptor molecule, facilitating the transfer of client proteins between the Hsp70 and Hsp90 chaperone systems. Hop functions both intracellularly and extracellularly and has been implicated in many processes involved in cancer progression, including cell migration and invasion. Little is known about the mechanisms or domains by which extracellular Hop functions. In addition, little is known about the effects of Hop on signalling molecules involved in cell migration and invasion through regulation of actin dynamics. It was hypothesised that both extracellular and intracellular pools of Hop would regulate distinct cell migration processes by activation of cell signalling pathways or direct interactions with signalling intermediates. HS578T cells were treated with recombinant full length and truncated murine Hop proteins (overexpressed and purified in this study) to determine the effects of extracellular Hop and the independent domains on cell migration processes. Additionally, RNA interference (RNAi) techniques were used to determine the effect of Hop knockdown on cell migration related signalling intermediates and cell morphologies. A short hairpin RNA (shRNA) system for the stable knockdown of Hop was developed and used for a number of these studies. Treatment of HS578T cells with the TPR2A2B and TPR1 domains of Hop resulted in a significant decrease in cell migration and caused changes in the actin cytoskeleton and extracellular matrix proteins, gelatin and fibronectin. RhoC immunoprecipitated in a common complex with Hop and Hsp90. Hop knockdown reduced levels of actin and total RhoC, as well as active RhoC. In addition, knockdown of Hop resulted in a reduced migratory phenotype. We interpreted these data to indicate that intracellular Hop played a role in cell migration through regulation of RhoC activity, either through a direct interaction between Hop and RhoC, or an indirect interaction of RhoC with the Hsp90 multichaperone heterocomplex. Taken together, the data suggested that extracellular and intracellular Hop played distinct roles in extracellular and intracellular processes that lead to actin dynamics and cell migration. Understanding the mechanistic role of Hop in these processes is essential as it would aid in assessing the viability of Hop as a potential drug target for the treatment of metastatic cancers. , Thesis (MSc) -- Faculty of Science, Biochemistry, Microbiology and Biotechnology, 2014
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Date Issued: 2014

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