UWCScholar
This repository serves as a digital archive for the preservation of research outputs from the University of the Western Cape.
Communities in UWCScholar
Select a community to browse its collections.
Recent Submissions
Longitudinal impact of past-year reproductive coercion on contraceptive use dynamics in Sub-Saharan Africa: evidence from eight population-based cohorts
(Elsevier Ltd, 2024) Omoluabi, Elizabeth; Wood, Shannon N; Thomas, Haley L
Background: Reproductive coercion (RC) is a type of abuse where a partner intentionally attempts to interfere with fertility through deception or violence, often by manipulating one's contraceptive use or reproductive decision-making. Cross-sectional studies on the magnitude of RC across sub-Saharan Africa have noted associations with contraceptive use. No studies have longitudinally examined RC experiences as related to future contraceptive dynamics, including discontinuation or forgoing use altogether. Methods: Two rounds of longitudinal population-based cohorts across eight sites in sub-Saharan Africa, from November 2020 to January 2023, were used to prospectively examine past-year RC's impact on future contraceptive dynamics (discontinuation and switching vs. continuation for contraceptive users at baseline; adoption vs. continued non-use for contraceptive non-users at baseline) using bivariate and multivariable multinomial and logistic regression. Findings: Minimal differences in women's past-year RC experiences were observed over a two-year period. In many settings, RC prevalence decreased. Only in Uganda did past-year RC increase between rounds (15.8% to 17.8%). RC's impact on contraceptive dynamics over one year differed by setting. In Burkina Faso, women with past-year RC had a three-fold increased risk of discontinuing contraception, as compared to continuing (RRR = 2.63; 95% CI = 1.28–5.42; p<0.01). In Uganda, past-year RC was marginally associated with reduced odds of contraceptive adoption, compared to continued non-use (p<0.1). Interpretation: In this first longitudinal study of RC, trajectories varied across settings, as did RC's impact on contraception, affirming the importance of context. Future work should clarify RC trajectories and drivers thereof. Providers must be aware of RC leading to potential discontinuation. Contraceptive provision must be flexible and reflect women's life circumstances, including partner dynamics. Funding: This work was supported, in whole, by the Bill & Melinda Gates Foundation [ INV-046501 and INV-009639]. Under the grant conditions of the Foundation, a Creative Commons Attribution 4.0 Generic License has already been assigned to the Author Accepted Manuscript version that might arise from this submission.
Towards cosmography of the local universe
(National University of Ireland Maynooth, 2024) Adamek, Julian; Clarkson, Chris; Durrer, Ruth
Anisotropies in the distance–redshift relation of cosmological sources are expected due to large-scale inhomogeneities in the local Universe. When the observed sources are tracing a large-scale matter flow in a general spacetime geometry, the distance–redshift relation with its anisotropies can be described with a geometrical prediction that generalises the well-known Friedmann-Lemaître-Robertson-Walker result. Furthermore, it turns out that a finite set of multipole coefficients contain the full information about a finite-order truncation of the distance–redshift relation of a given observer. The multipoles of the distance–redshift relation are interesting new cosmological observables that have a direct physical interpretation in terms of kinematical quantities of the underlying matter flow. Using light cones extracted from N-body simulations we quantify the anisotropies expected in a Λ cold dark matter cosmology by running a Markov chain Monte Carlo analysis on the observed data. In this observational approach the survey selection implements an implicit smoothing scale over which the effective rest frame of matter is fitted. The perceived anisotropy therefore depends significantly on the redshift range and distribution of sources. We find that the multipoles of the expansion rate, as well as the observer’s velocity with respect to the large-scale matter flow, can be determined robustly with our approach.
Using multisource remotely sensed data and cloudcomputing approaches to map non-native species in thesemi-arid savannah rangelands of Mpumalanga, South Africa
(Taylor & Francis, 2025) Maphanga, Thabang; Dube, Timothy; Sibanda, Mbulisi; Gxokwe, Siyamthanda
Semi-arid savannah rangelands are diverse environments (in terms of species) that play an important role in sustaining biodiversity and providing ecosystem services. However, the emergence of non-native species, as well as bush encroachment, are currently threatening these (semi-arid rangeland and grassland) ecosystems. The purpose of this study was therefore to map and quantify the spatial extents of non-native woody vegetation in the Kruger National Park and surrounding communal areas in Mpumalanga, South Africa. To achieve the study’s objectives, Sentinel-1 and Sentinel-2 remotely sensed data were combined and analysed using the random forest (RF) machine-learning algorithm in the Google Earth Engine (GEE) cloud computing platform. Specifically, spectral bands and selected spectral derivatives, e.g. enhanced vegetation index (EVI2), normalized difference moisture index (NDMI) and normalized difference phenology index (NDPI) were computed and used to map non-native woody vegetation. After optimizing the model combination, the classification outputs had an overall accuracy of 70%, with class accuracies such as producer’s accuracy (PA) and user’s accuracy (UA) ranging from 67% to 95%.It was shown in this study that using Sentinel-2 and Sentinel-1 data together led to better overall accuracy than using single sensor models when mapping semi-arid savannah rangelands. It was also found in this study that the overall classification accuracy of non-native (invasive) species using optical sensors was higher than in previous studies. On a free platform like GEE, it was possible to utilize advanced classification processes to fully exploit the informative content of Sentinel-1 and Sentinel-2 data.
Copyright Law as it pertains to machine learning as an artificial intelligence pillar in South Africa
(University of the Western Cape, 2024) Fisher, Amy; Wandrag, Riekie
Globally, artificial intelligence has drawn much interest in the literature in most sectors of the economy. What many scholars have been grappling with is the relationship between artificial intelligence and legislation. Some of these areas include criminal law, labour law, ethics, amongst other areas. Hence, it is no surprise that artificial intelligence also raises issues in copyright law, mainly concerning a critical question about what protection authors and owners have with regard to artificial intelligence and copyright law. Based on an examination of artificial intelligence and copyright law (that is, the existing intellectual property system), this mini-thesis contends that the current legislation is inadequate to keep abreast with the advances and complexity of artificial intelligence. The absence of updated copyright legislation is a serious concern for artificial intelligence authors and owners. This problematic phenomenon presents itself all over the world, such as the United States, the United Kingdom, China and many other countries. Several efforts made to protect the author and owner has rendered ineffective, due to the insurmountable challenge of keeping pace with the rapid advances of technology.
Derivatives of pyrazole-based compounds as prospective cancer agents
(American Chemical Society, 2025) Alexander, Orbett T; Ramoba, Lesetja V.; Nzondomyo, Wakopo J.
Five pyrazole-based compounds, 3,5-dimethyl-1H-pyrazole, L1; 3,5-diphenyl-1H-pyrazole, L2; 3-(trifluoromethyl)-5-phenyl-1H-pyrazole, L3; 3-(trifluoromethyl)-5-methyl-1H-pyrazole, L4; and 3,5-ditert-butyl-1H-pyrazole, L5 were synthesized from a typical condensation reaction of β-diketone derivatives with hydrazine hydrate reagent and characterized using various spectroscopic techniques such as FT-IR, UV-vis, 1H and 13C NMR, and LC-MS spectroscopy. L1 was further analyzed by single-crystal X-ray diffraction, and the N1-N1′ bond distance was found to be 1.361(3) Å and correlated well with other pyrazole-based compounds. The short-term cytotoxicity of 10 μM pyrazole compounds (L1-L5) was evaluated against pancreatic (CFPAC-1 and PANC-1), breast (MDA-MB-231 and MCF-7), and cervical (CaSki and HeLa) cancer cell lines using the MTT cell viability assay. Cisplatin and gemcitabine were included as positive control drugs followed by the determination of the half-maximal effective concentrations of prospective compounds. L2 and L3, respectively, displayed moderate cytotoxicity against CFPAC-1 (61.7 ± 4.9 μM) and MCF-7 (81.48 ± 0.89 μM) cell lines.