WIReDSpace

Welcome to WIReDSpace (Wits Institutional Repository on DSpace)

For queries relating to content and technical issues, please contact IR specialists via this email address : openscholarship.library@wits.ac.za,
Tel: 011 717 4652 or 011 717 1954

Photo by @inspiredimages

Communities in WIReDSpace

Select a community to browse its collections.

Now showing 1 - 5 of 19

Recent Submissions

  • Thumbnail Image
    Item type:Item,
    Prenatal fumonisin exposure impairs bone development via disturbances in the OC/Leptin and RANKL/RANK/OPG systems in weaned rat offspring
    (MDPI, 2023-05) Tomaszewska, Ewa; Rudyk, Halyna; Muszynski, Siemowit; Hułas-Stasiak, Monika; Leszczynski, Norbert; Mielnik-Błaszczak, Maria; Donaldson, Janine; Dobrowolski, Piotr
    The goal of the current study was to examine the effects of prenatal exposure to fumonisins (FBs) on bone properties and metabolism in weaned rat offspring divided into groups intoxicated with FBs at either 0 (the 0 FB group), 60 (the 60 FB group), or 90 mg/kg b.w. 0 (the 90 FB group). Female and male offspring exposed to FBs at a dose of 60 mg/kg b.w. had heavier femora. Mechanical bone parameters changed in a sex and FBs dose-dependent manner. Growth hormone and osteoprotegerin decreased in both sexes, regardless of FBs dose. In males osteocalcin decreased, while receptor activator for nuclear factor kappa-B ligand increased regardless of FBs dose; while in females changes were dose dependent. Leptin decreased in both male FBs-intoxicated groups, bone alkaline phosphatase decreased only in the 60 FB group. Matrix metalloproteinase-8 protein expression increased in both female FBs-intoxicated groups and decreased in male 90 FB group. Osteoprotegerin and tissue inhibitor of metalloproteinases 2 protein expression decreased in males, regardless of FBs dose, while nuclear factor kappa-B ligand expression increased only in the 90 FB group. The disturbances in bone metabolic processes seemed to result from imbalances in the RANKL/RANK/OPG and the OC/leptin systems
  • Thumbnail Image
    Item type:Item,
    Basal intestinal morphology, immunolocalization of Leptin and Ghrelin and their receptors in newborn Wistar rats after prenatal exposure to fumonisins
    (MDPI, 2023-05) Tomaszewska, Ewa; Rudyk, Halyna; Dobrowolski, Piotr; Arciszewski, Marcin B.; Donaldson, Janine; Kras, Katarzyna; Abramowicz, Beata; Kuc, Damian; Muszynski, Siemowit
    Animal feed is very frequently contaminated with different types of mold, the metabolites of which are toxic to living organisms. Mold-contaminated cereal is rich in heat-resistant and harmful metabolites such as fumonisins (FBs). The amount of FBs consumed as part of animal feed, including livestock feed, is unknown. Therefore, this study aimed to evaluate the effects of maternal oral FB intoxication on basal duodenum morphology and the immunolocalization of gut hormones responsible for food intake (leptin and ghrelin), as well as their receptors, in newborn rat offspring. Pregnant Wistar rats were randomly allocated to one of three groups: a control group or one of two FB-intoxicated groups (60 or 90 mg FB/kg b.w., respectively). Basal morphological duodenal parameters changed in a dose- and sex-dependent manner. The intensity of the ghrelin immunoreaction was unchanged in females, while in males it increased after FB exposure (60 mg/kg b.w.), with a simultaneous decrease in expression of the ghrelin receptor. Leptin and its receptor immunoreaction intensity was decreased in both sexes following FB exposure. The current study highlighted the potential involvement of intestinal ghrelin and leptin in the metabolic disturbances observed later in life in offspring that were prenatally exposed to fumonisins.
  • Thumbnail Image
    Item type:Item,
    Comparing the performance of mobile and static LiDAR in detecting underground rock deformation
    (University of the Witwatersrand, Johannesburg, 2025) Dlamini, Lubanzi Zolibonga Desree; Adam, Elhadi; Atif, Iqra
    Accurate deformation monitoring is essential for ensuring structural stability in underground mining environments. This study, therefore, evaluates the performance of mobile and static LiDAR scanners in capturing and analysing rock deformation within a controlled underground mock mine. The point cloud data was collected pre-and post-deformation using both scanning platforms and was processed in the open source CloudCompare for registration, segmentation and deformation analysis. The comparative assessment focused mainly on point cloud characteristics, surface errors and deformation mapping accuracy. The comparative results show that static LiDAR has a higher point resolution and lower surface errors, while mobile LiDAR allows for rapid data acquisition with a broader spatial coverage. Deformation measurements obtained from both platforms show a strong correlation with the field measurements; this is confirmed by statistical analysis with 𝑅2 Values greater than 0.99. Furthermore, a paired t-test resulting in a p-value of 0.188 exceeded the commonly used threshold of 0.05, indicating no significant difference between the two methods. Moreover, a trade-off between accuracy and operational efficiency was identified; where static LiDAR ensures high data quality, it is constrained by occlusions and acquisition time. Meanwhile, mobile LiDAR is more adaptable to confined environments. These findings contribute to optimising LiDAR-based deformation monitoring strategies in underground mining, balancing precision, efficiency, and practical implementation.
  • Thumbnail Image
    Item type:Item,
    Challenges and Opportunities of Corporate Climate Action in South Africa: An Investigation Using the Aqal Framework of The Integral Theory
    (University of the Witwatersrand, Johannesburg, 2022) Dhlamini, Neliswa Proserpina; Schwaibold, Ute
    Climate change is a complex, wicked problem of the 21st century caused by greenhouse gas (GHG) emissions produced by economic growth endeavours and urban life. World leaders have signed agreements to work towards Net Zero emissions by 2050 and keep global average temperatures below 2°C. However, almost a decade later, global temperatures are reaching all-time highs and there seems to be no change in sight. Because the private sector is the leading emitter, this study aimed to determine the personal and cultural values, beliefs and perceptions, behaviours, and systems that foster (opportunities) or impede (challenges) corporate climate action in South Africa. A holistic approach – the AQAL (all quadrants, all levels, all lines, all states, all types) framework of the Integral Theory – was used, considering that South Africa is a developing country that is dealing with a number of urgent environmental, social, and economic challenges and understanding the complexity of social issues and the South African context particularly. Data were collected through interviews with environmental/sustainability specialists practicing in the private sector, environmental and business organisations, government and academics in sociology, business, and climate change. Furthermore, content analysis of climate change legislation, policies and guidelines relevant to South Africa, as well as climate change related business reports of a sample of JSE listed companies was conducted. The results showed that companies are starting to consider climate change in relation to their operations, however, they were perceived to be performing poorly, only taking opportunities that are easy and quick to return benefit and not taking transformative climate actions to reengineer their core operations. The challenges that were found to be impeding corporate climate action in South Africa were uncertainties around climate change, ineffectiveness of climate change campaigns and guidelines in enforcing climate action, a perverse economic system, socio-economic priorities that take precedence over climate action requirements, South African social dynamics relating to poverty and aspirations that stymie the activism culture, a lack of financial and technical capacity and expertise, tension between young, creative thinkers who are more concerned about climate change and old leaders who may be skeptics and make decisions based only on financial flows, a lack of infrastructure for certain climate related actions such as recycling, issues relating to the coal and energy sector and national governance. The opportunities that could be leveraged related to platforms like the NBI where businesses can collaborate on policy, global initiatives, and workable solutions, opportunities to collaborate with academics and other research organisations who are producing contextual data and solutions, young creative thinkers whose ideas can be integrated into decisions making processes, existing climate change awareness and activism by NGOs and conscious civil society, opportunities for government and business to band together to share resources, technical capacity and expertise, leveraging public and private funds to invest in climate change projects and infrastructure, possibilities of diversifying the energy mix through private energy production and grid feed-in, and positioning the country to receive international aid. Recommendations to mitigate the barriers of corporate climate action and leverage opportunities include collaboration between the different stakeholders to come up with comprehensive solutions and policies to create and enabling environment for positive business response, government finding the political will to make hard decisions, combining business and government resources, capacities and competencies, delegating certain mandates to other stakeholders such as business and environmental organisations, opening up communication pathways for bottom-up influence in business, and business and government leveraging their roles as opinion shapers to educate, raise awareness, shift mindsets and reframe aspirations.
  • Thumbnail Image
    Item type:Item,
    Cooling by dousing with cold water does not alter the pathophysiological biochemical changes induced by capture in blesbok (damaliscus pygargus phillipsi)
    (2023) Leiberich, Marion; Fitte, Agustina; Burroughs, Richard E.J.; Steyl, Johan Christian Abraham; Goddard, Amelia; Haw, Anna Jean; Boesch, Jordyn Marie; Kohn, Tertius Abraham; Meyer, Leith Carl Rodney
    Wild animals are commonly captured for conservation, research, and wildlife management purposes. However, capture is associated with a high risk of morbidity or mortality. Capture-induced hyperthermia is a commonly encountered complication believed to contribute significantly to morbidity and mortality. Active cooling of hyperthermic animals by dousing with water is believed to treat capture-induced pathophysiological effects, but remains untested. This study aimed to determine the pathophysiological effects of capture, and whether cooling by dousing with cold water effectively reduces these effects in blesbok (Damaliscus pygargus phillipsi). Thirty-eight blesbok were randomly allocated into three groups: a control group that was not chased (Ct, n=12), chased not cooled (CNC, n=14), and chased plus cooled group (C+C, n=12). The CNC and C+C groups were chased for 15 min prior to chemical immobilization on day 0. Animals in the C+C group were cooled with 10 L of cold water (4 C) for 10 min during immobilization. All animals were immobilized on days 0, 3, 16, and 30. During each immobilization, rectal and muscle temperatures were recorded, and arterial and venous blood samples collected. Blesbok in the CNC and C+C groups presented with capture-induced pathophysiological changes characterized by hyperthermia, hyperlactatemia, increased markers of liver, skeletal, and cardiac muscle damage, hypoxemia, and hypocapnia. Cooling effectively returned body temperatures to normothermic levels, but neither the magnitude nor the duration of the pathophysiological changes differed between the CNC and C+C groups. Therefore, at least in blesbok, capture-induced hyperthermia appears not to be the primary cause of the pathophysiological changes, but is more likely a clinical sign of the hypermetabolism resulting from capture-induced physical and psychological stress. Although cooling is still recommended to prevent the compounding cytotoxic effects of persistent hyperthermia, it is unlikely to prevent stress- and hypoxia-induced damage caused by the capture procedure.