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    A field, petrographic and geochemical investigation of norite and anorthosite rocks related to the potholed Merensky Reef sub-facies at Northam Platinum Zondereinde mine, Western Bushveld Complex
    (University of the Witwatersrand, Johannesburg, 2025-10) Keikabile, Zanele; Hayes, Ben
    This research study is an investigation of norite and anorthosite bodies identified within potholed Merensky Reef in the southwestern extension of Northam Platinum’s Zondereinde Mine, situated in the Western Limb of the Bushveld Complex, South Africa. This study aims to understand the nature and impact of these bodies on the reef as well as constrain their effect on PGE grade and mining. Data from underground geological mapping and borehole logging is combined with petrography and bulk rock trace element geochemistry. Comparisons are also made with similar norites in the hanging wall and footwall of the Merensky Reef. Underground mapping and core logging demonstrate the unpredictable spatial distribution of these bodies, with both sharp and gradational contacts being observed. Potholing and slumping of the reef also appear to be closely related to the norite-anorthosite bodies. Microstructural observations from thin sections indicate there are textural similarities between the norite bodies and the hanging wall norite to the Merensky Reef, which is also supported by the bulk rock trace element compositions. These similarities between the norite bodies and the layered stratigraphy above the Merensky Reef suggest they are connected (i.e., cogenetic) to the layered stratigraphy and they are not of an intrusive or exotic origin. The possible relationship between the norite-anorthosite bodies and Iron-Rich Ultramafic Pegmatoids is also explored, as the latter commonly replace the norite and anorthosite bodies at Zondereinde Mine. It is also shown that the norite-anorthosite bodies are barren in terms of PGE grade, and they therefore significantly dilute the PGE grades of the mined Merensky Reef, such that they pose substantial challenges to mining operations. A recommendation from this study is that there should be increased diamond drilling to better delineate the spatial distribution of these bodies. This will inform mining strategies, increase efficiency, and minimise geological losses in the southwestern extension of Zondereinde Mine.
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    Potential functional trade-offs in skeletal muscle and verte brae characteristics between three ventrally keeled and smooth arboreal snake species (Philothamnus)
    (University of the Witwatersrand, Johannesburg, 2025) Janse van Rensburg, Ilanka; Reddy, Deran; Engelbrecht, Hanlie M
    The study species are closely related and morphologically very similar, however two are ventrally keeled (Philothamnus natalensis and Philothamnus semivariegatus) while the other is ventrally smooth (Philothamnus hoplogaster). Given that most ventrally keeled snakes are arboreal, ventral keeling is presumably advantageous for climbing; yet its absence in some arboreal lineages suggests functional trade-offs, potentially associated with aquatic habits or other ecological constraints. The research aims to look at muscle strength indicators as a reason to the loss of ventral keeling in snakes due to possible energetic trade-offs. The vertebral architecture, muscle size in cross-sectional area, and muscle fibre type composition were used to examine differences in the muscle load bearing capacity of ventrally keeled and ventrally smooth snakes. Examining these strength indicators was executed through Computed Tomography (CT) scans of the vertebrae, histological staining for the muscle cross-sectional area and histochemical staining for the muscle fibre types. Certain epaxial (semispinalis spinalis, longissimus dorsi, and iliocostalis) and hypaxial (costocutaneous inferior, transversus ventralis, and scutali interscutali complex) muscles were selected for analysis. PCAs, K-means analysis, and ANOVAs and Kruskal-Wallis tests were used for statistical analysis. The hypothesis of the study was that ventrally smooth species would have a greater muscle load bearing capacity than ventrally keeled species. The results showed that although the ventrally smooth P. hoplogaster was distinct from the other species for most muscle strength indicators, it was unexpectedly due to consistently lower measurements in the muscle strength indicators. They had smaller vertebral structures and muscle cross-sectional sizes and more oxidative muscle fibre types than the keeled species.
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    Assessing perceptions of environmental management in the construction industry: a case study of construction companies in the Gauteng Province
    (University of the Witwatersrand, Johannesburg, 2025-10) Hlungwane, Rhulani Hlulani; Kubanza, Nzalalemba Serge
    This study looks into the perceptions of construction industry professionals working for grade 9 CIDB registered companies within the Gauteng Province of South Africa. Given that construction is not only of high economic value but also of high environmental impact, understanding the perceptions of construction professionals regarding their obligation towards the environment is crucial for ensuring sustainability in the construction industry. Informed by Stakeholder Theory, Institutional Theory and the Theory of Planned Behavior, the investigation used a quantitative cross-sectional design entailing structured questionnaires among Environmental Officers (EOs) and Project Managers (PMs). There were 66 valid responses (35 EOs and 31 PMs) which were analyzed with descriptive and inferential statistics. Respondents showed a very high sense of consciousness and positive attitudes towards environmental regulations, with a 90% of them rating compliance at "extremely important." Yet environmental practice application remains reactive and inconsistent, with prevalence of the obsessions of audits rather than inherent commitment. Key inhibitions reported were lack of funds, insufficiency of commitment by management, lack of coordination and ambiguity of regulations. Notably, cost perception was a key inhibition reported and environmental compliance was viewed as an added cost burden. The study concludes that while environmental stewardship commitment at the theoretical level does exist, application is limited by structural, institutional and perceptual problems. Its recommendation for greater policy conformity, capacity building initiatives and organizational leadership acts to promote mainstreaming of sustainable construction practice. Such a result seeks to bring environmental policy closer to on-site practice for South Africa's construction industry.
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    Taxonomy, ecology and conservation of selected rare and threatened Kniphofia species
    (University of the Witwatersrand, Johannesburg, 2025-10) Hlongwane, Ndumiso; Witkowski, Ed T.F.; Victor, Janine
    Kniphofia is a genus of 71 species with an African distribution. Forty-eight of these occur in southern Africa. The genus has several taxonomic issues that require investigation, and these difficulties are related to intermediate forms that put these species' taxonomic status in doubt. There are currently 14 threatened species of Kniphofia as reported on the SANBI Redlist, however, a detailed study on the threats and population size structure has only been conducted on one Critically Endangered (CR) species, Kniphofia umbrina from Eswatini. This study was prompted by a lack of knowledge concerning the current population sizes, structures, threats, and distribution of 13 other threatened taxa. Most of these 13 taxa are poorly known taxonomically. The aim was to revise the taxonomic status of five threatened Kniphofia taxa (K. leucocephala, K. pauciflora, K. drepanophylla, K. ichopensis var. aciformis, and K. crassifolia), and their five morphologically similar congeneric species (K. baurii, K. ichopensis var. ichopensis, K. laxiflora, K. angustifolia, and K. fibrosa) (eight species plus two varieties), conduct population studies on these species, and assess their conservation status. Morphological characters (qualitative and quantitative) were evaluated in 191 specimens from South African herbaria. The data were analysed using the Statistical Package for the Social Sciences (SPSS) and Paleontological Statistics (PAST). The findings relating to K. leucocephala and K. pauciflora suggest that the two species are morphologically similar, although they exhibit different flower colours. The two species show a different altitudinal range, differ in flowering time and are distributed in different vegetation types. Morphological and flowering similarities were also noted between K. baurii and K. drepanophylla. These two species differed in altitude and vegetation type. A close morphological similarity between K. baurii and K. fibrosa was noted but needs further investigation. Kniphofia ichopensis var. ichopensis was morphologically similar to K. ichopensis var. aciformis and K. angustifolia but significantly different to K. laxiflora. Similar flowering times were noted between K. ichopensis var. ichopensis and K. ichopensis var.aciformis, while those of K. angustifolia and K. laxiflora differed. There was no altitudinal difference between K. ichopensis var. ichopensis and both K. ichopensis var. aciformis and K. laxiflora. However, K. angustifolia differed in altitude from K. ichopensis var. ichopensis. Their distribution within vegetation types also differed among all these species. Due to the absence of herbarium material for K. crassifolia, the study could not establish its taxonomic relationship with K. fibrosa. A neotype was designated for K. leucocephala in this study due to a missing type specimen. Although the study recognised most of the compared Kniphofia species as morphologically indistinguishable species, taxonomic changes were not made due to a lack of a detailed phylogenetic study inclusive of all the species in this genus. Therefore, the status quo of the currently recognised morphological units and Codd species concept is maintained at present. The study also recognised the work done by Ramdhani et al. (2009) but suggests that the work needs to be expanded to better understand monophyly and species relationships within this genus. A single population of each of the paired Kniphofia species was assessed in KwaZulu-Natal, and the combined population sizes were found to be very low (220 individuals), of which 44% were reproductive adults. Least Concern (LC) species had higher population sizes compared to threatened species, with sizes ranging from 14 to 40 plants. Bimodal and J-shaped size class distribution (SCD) were the most common across all populations, suggesting episodic recruitment and the domination of adult individuals. Of the three measures of SCD explored, plant height was the preferred measure for these species. Most of these populations were in areas dominated by grassy vegetation, with disturbance factors such as the prevalence of invasive alien plant species (IAPs), rubbish dumping, trampling, and overgrazing, which may cause habitat degradation. Field search of K. crassifolia subpopulations was fruitless, suggesting a possible extinction in the wild. Using population data from this current study, the status of K. leucocephala and K. pauciflora was confirmed to be Critically Endangered (CR). This is due to high risks from IAP species such as Eucalyptus, urban expansion, reduction in habitat quality and low Area of Occupancy (AOO) and Extent of Occurrence (EOO). Although K. drepanophylla currently has 15 populations, only one is known to be in a conserved area, and the populations outside the nature reserves face a higher risk of trampling, uncontrolled fires, overgrazing, and harvesting on communal land. Therefore, the study proposes a Vulnerable (VU) category and immediate re-assessment of the other populations that were not surveyed during this study to confirm this proposed status. There was limited information on the status of K. ichopensis var. aciformis prior to this study; however, it has been established that there are only four currently known populations of this species. The surveyed population is threatened by cattle trampling, overgrazing and unmanaged IAP, and three of its populations occur in habitats that are poorly protected, which also makes it vulnerable to extinction. Therefore, a VU category is proposed for this species. Although K. baurii, K. ichopensis var. ichopensis, K. laxiflora, K. angustifolia, and K. fibrosa are listed as LC, there were few individuals (all <40) in each of these populations. These populations were mainly threatened by trampling from humans and livestock, harvesting, rubbish dumping, IAP and overgrazing. The results suggest that although these species are categorised as LC, they are facing a serious decline due to multiple threats and will also need conservation and monitoring directed towards them. The current conservation status for these species was provisionally retained, but more extensive surveys, preferably of all known populations, are a priority. The study provided baseline information for suitable conservation adaptive management plans, with fencing populations outside conserved areas proposed. Further studies are needed to assess suitable fire regimes and the potential to augment them with additional seedlings to increase their viability, given the very small population sizes.
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    Toolkit for high-dimensional quantum light
    (University of the Witwatersrand, Johannesburg, 2025) Gounden, Neelan
    The manipulation of light’s various degrees of freedom, known as structuring light, has become useful in the development of both classical and quantum technologies. Two-dimensional quantum states have been investigated optically for many years, but have a limited amount of information which can be encoded into them. In order to surpass this limitation, high-dimensional quantum states have also been studied using light in quantum optics experiments. High-dimensional quantum states al- low for large amounts of information to be encoded into the states and bi-photon quantum states present an added advantage of non-local measurements. However, high-dimensional bi-photon states impose challenges such as efficient generation and detection of the states. In this dissertation we explore a generation technique for high dimensional states as well efficient detection techniques and methods which can be employed to com- bat challenges which may arise. The high-dimensional degrees of freedom that will be used are orbital angular momentum and transverse spatial position. The cor- relations between a pair of entangled photons are exploited in order to perform measurements on a bi-photon high-dimensional quantum state. The theory and experimental implementation of characterisation techniques for high-dimensional quantum states are discussed such as OAM bandwidth measurements, Bell inequal- ity violations and reconstructing the information of a quantum state using quantum state tomography. Quantum ghost imaging is a quantum imaging technique that uses the transverse position correlations between the entangled photons. The theory and experimental implementation of ghost imaging using high-dimensional bi-photon position states is explored. The uncertainty principle between angular position and OAM is inves- tigated for a bi-photon quantum state and how a non-local induced OAM spread is limited by the spread in OAM of the initial quantum state produced from spon- taneous parametric down-conversion. A link between a quantum search algorithm (Grover’s algorithm) and quantum ghost imaging is investigated and similarities are drawn. The complexity of Grover’s algorithm is alleviated by leveraging high- dimensional bi-photon position states.