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- This community is for all faculties and schools' research outputs and publications by Wits academics and researchers.
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- This Community hosts a collection of electronic theses and dissertations (ETDs) submitted by doctoral and masters' students of Wits University.
- This community is for all faculties and schools' theses and dissertations by masters and doctoral students.
Recent Submissions
Two-dimensional turbulent classical and momentumless thermal wakes
(University of the Witwatersrand, Johannesburg, 2023-07) Mubai, Erick; Mason, David Paul
The two-dimensional classical turbulent thermal wake and the two-dimensional momentumless turbulent thermal wake are studied. The governing partial differential equations result from Reynolds averaging the Navier-Stokes, the continuity and energy balance equations. The averaged Navier-Stokes and energy balance equations are closed using the Boussinesq hypothesis and an analogy of Fourier’s law of heat conduction. They are further simplified using the boundary layer approximation. This leads to one momentum equation with the continuity equation for an incompressible fluid and one thermal energy equation. The partial differential equations are written in terms of a stream function for the mean velocity deficit that identically satisfies the continuity equation and the mean temperature difference which vanishes on the boundary of the wake. The mixing length model and a model that
assumes that the eddy viscosity and eddy thermal conductivity depend on spatial variables only are analysed. We extend the von Kármán similarity hypothesis to thermal wakes and derive a new thermal mixing length. It is shown that the kinematic viscosity and thermal conductivity play an important role in the mathematical analysis of turbulent thermal wakes. We obtain and use conservation laws and associated Lie point symmetries to reduce the governing partial differential equations to ordinary differential equations. As a result we find new analytical solutions for the two-dimensional turbulent thermal classical wake and momentumless wake. When the ordinary differential equations cannot be solved analytically we use a numerical shooting method that uses the two conserved quantities as the targets.
Determinants of sub-optimal glycaemic control among patients enrolled in a medicine dispensing programme in Kwazulu-Natal: A cohort study, 2018 – 2021
(University of the Witwatersrand, Johannesburg, 2023) Johnston, Leigh Clare
Background: In South Africa, type 2 diabetes mellitus (T2DM) is a growing public health problem, thus, by 2030, 50% of T2DM patients, receiving treatment, must achieve optimal glycaemic control (haemoglobin A1c (HbA1c) ≤7%). The CCMDD (Central Chronic Medicines Dispensing and Distribution) programme allows glycaemically-stable patients to collect their medication from community-based pick-up points. While the CCMDD is a large public health programme, there is a paucity in stakeholder’s knowledge of T2DM patients glycaemic control over time. We determined glycaemic control for CCMDD-enrolled T2DM patients in eThekwini, South Africa from 2018-2021, as well as the rate and predictors of becoming sub-optimally controlled.
Methods: We performed a cohort study, linking HbA1c data from the National Health Laboratory Service to CCMDD-enrolled patients in eThekwini, South Africa from 2018–2021. We included patients optimally controlled at their baseline HbA1c, and having ≥1 repeat test available. We used Kaplan Meier analysis to assess survival rates and Cox regression to determine associations between time to sub-optimal control (HbA1c > 7%) and several factors. Adjusted hazard ratios (aHR), 95% confidence interval (95% CI), and p-values are reported.
Results: Of 41145 T2DM patients enrolled in the CCMDD, 7960 (19%) had an available HbA1c result over the study period. A quarter of patients (2147/7960; 27%) were optimally controlled at their baseline HbA1c. Of those controlled at baseline, 695 (32%) patients had a repeat test available, with 35% (242/695) changing their status to sub-optimal control. Patients prescribed dual-therapy had a higher risk of sub-optimal glycaemic control (aHR: 1.503; 95% CI: 1.16–1.95; p-value=0.002) compared to those on monotherapy. HbA1c testing frequency per national guidelines (aHR: 0.46; 95% CI: 0.24–0.91; p-value=0.024) was associated with a lower hazard of sub-optimal glycaemic control.
Conclusions: HbA1c monitoring, in line with testing frequency guidelines, is needed to flag sub- optimally controlled patients who become ineligible for CCMDD enrolment. Patients receiving dual-therapy may require special consideration. Addressing these shortfalls can assist planning and implementation to achieve 2030 targets.
Extension of efficacy range for targeted malariaelimination interventions due to spillover effects
(NATURE PUBLISHING GROUP) Jade Benjamin-Chung; Haodong Li; Anna Nguyen; Gabriella B Heitmann; E et al; Immo Kleinschmidt
Transethnic genomic informed risk assessment for Alzeheimers disease an international Hundred K and Cohorts Consortium
PM Sleiman; H-Q Qu; JJ Connolly; F Mentch; Stephen Tollman; Ananyo Choudhury; Michele Ramsay; E et al
Adverse Pregnancy Outcomes Among Women with Human Immunodeficiency Virus Taking Isoniazid Preventive Therapy During the First Trimester
(OXFORD UNIV PRESS INC) A Gupta; M Hughes; J Leon-Cruz; A Avihingsanon; Noluthando Mwelase; E et al