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Communities in WIReDSpace
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- This community is for all faculties and schools' research outputs/journal articles by Wits academics and researchers.
- This community hosts traditional outputs such as published and unpublished research articles, conference papers, book chapters and other research outputs authored by Wits academics and researchers. Items in this collection are also mapped to relevant collections within the Faculties/Schools/Departments communities for more specific browsing and searching.
- This community is for all faculties and schools' electronic theses and dissertations (ETDs) by masters and doctoral students. NB: All electronic theses and dissertations to be edited and moved/uploaded here.
- This community for all Wits Inaugural lectures.
- This community is for all Wits Libraries staff presentations and publications.
Recent Submissions
Parenting in place: young children's living arrangement and migrants' sleep health in South Africa
(Wiley, 2023-06) Madhavan, Sangeetha; Kim, Seung Wan; White, Michael; Gomez‐Olive, Xavier
Migration research tends to treat childrearing as a secondary role for migrants. By prioritising the economic objectives of migration, most models present migrants as either delaying childbearing or, if they have young children, not living with them. However, migration has become increasingly feminised, the types of mobility more varied, while the returns to migration remain uncertain at best. At the same time, norms around childrearing are shifting, and the capacity of kin to take care of children may be weakening. In such contexts, migrants may not want to or be able to be separated from their children. Confronting such difficult decisions and their consequences may be reflected in poor sleep health for the migrant parent. We draw on data from the Migration and Health Follow‐Up Study (MHFUS) in South Africa to examine the following questions: (i) To what extent is children's coresidence associated with sleep health for migrant parents? (ii) Do effects vary by sex of migrant? and (iii) Do effects vary by location of migrant? Results from propensity score matching confirm that migrants who coreside with all their young children are more likely to experience healthy sleep compared to those who have nonresident or no young children. However, stratified analysis shows that these effects are only significant for women and those not living in Gauteng province. The value of these findings is underscored by the need for research on the well‐being of migrant parents who are negotiating multiple agendas in economically precarious and physically insecure destinations.
An inertial-type method for solving image restoration problems
(Springer, 2023-07) Izuchukwu, Chinedu; Shehu, Yekini; Reich, Simeon
We first establish weak convergence results regarding an inertial Krasnosel’skiĭ-Mann iterative method for approximating common fixed points of countable families of nonexpansive mappings in real Hilbert spaces with no extra assumptions on the considered countable families of nonexpansive mappings. The method of proof and the imposed conditions on the iterative parameters are different from those already available in the literature. We then present some applications to the Douglas–Rachford splitting method and image restoration problems, and compare the performance of our method with that of other popular inertial Krasnosel’skiĭ-Mann methods which can be found in the literature.
Introducing a secondary segmentation to construct a radiomics model for pulmonary tuberculosis cavities
(Springer, 2023) du Plessis, Tamarisk; Ramkilawon, Gopika; Duncombe Rae, William Ian; Botha, Tanita; Martinson, Neil Alexander; Dixon, Sarah Alice Parry; Kyme, Andre; Sathekge, Mike Michael
Purpose: Accurate segmentation (separating diseased portions of the lung from normal appearing lung) is a challenge in radiomic studies of non-neoplastic diseases, such as pulmonary tuberculosis (PTB). In this study, we developed a segmentation method, applicable to chest X-rays (CXR), that can eliminate the need for precise disease delineation, and that is effective for constructing radiomic models for automatic PTB cavity classification.
Methods: This retrospective study used a dataset of 266 posteroanterior CXR of patients diagnosed with laboratory confirmed PTB. The lungs were segmented using a U-net-based in-house automatic segmentation model. A secondary segmentation was developed using a sliding window, superimposed on the primary lung segmentation. Pyradiomics was used for feature extraction from every window which increased the dimensionality of the data, but this allowed us to accurately capture the spread of the features across the lung. Two separate measures (standard-deviation and variance) were used to consolidate the features. Pearson’s correlation analysis (with a 0.8 cut-off value) was then applied for dimensionality reduction followed by the construction of Random Forest radiomic models.
Results: Two almost identical radiomic signatures consisting of 10 texture features each (9 were the same plus 1 other feature) were identified using the two separate consolidation measures. Two well performing random forest models were constructed from these signatures. The standard-deviation model (AUC = 0.9444 (95% CI, 0.8762; 0.9814)) performed marginally better than the variance model (AUC = 0.9288 (95% CI, 0.9046; 0.9843)).
Conclusion: The introduction of the secondary sliding window segmentation on CXR could eliminate the need for disease delineation in pulmonary radiomic studies, and it could improve the accuracy of CXR reporting currently regaining prominence as a high-volume screening tool as the developed radiomic models correctly classify cavities from normal CXR.
Female condom color and scent preference in Durban, South Africa
(Elsevier, 2023-06) Beksinska, Mags; Smit, Jenni; Mona, Amanda; Maphumulo, Virginia; Mphili, Nonhlanhla; Manzini-Matebula, Nontsikelelo; Chidarikire, Thato
Objectives: To assess preferences for female condom (FC) colors and scents.
Study design: Women aged 18–40 years were randomized to one of three FCs (FC2, Cupid1, Cupid2) two of
which offered a choice of color and scent (red/strawberry, purple/vanilla, natural/unscented). Women could
choose any variety within condom types while participating in an FC contraceptive efficacy study in South
Africa.
Results: One hundred and thirty-three women were allocated to each FC type. Strawberry was the most
popular variety for both FC2 and Cupid1 (60.9%, 78.3% respectively). Some women chose more than one
variety but few chose the natural.
Conclusions: Data support a clear preference for colored and scented FCs.
Implications: These data can inform FC programme managers to predict demand for different varieties of FC
and can adjust supply of FCs accordingly
The stability of C-peptide and insulin in plasma and serum samples under different storage conditions
(De Gruyter, 2023-07) Nkuna, Delhia X.; Khoza, Siyabonga P.; George, Jaya A.; Maphayi, Mpho R.
Objectives: C-peptide and insulin are peptide hormones and their stability is affected by a number of pre-analytical factors. The study aimed to investigate the impact of sample type, storage temperature and time delays before centrifugation and analysis on the stability of C-peptide and insulin.
Methods: Ten healthy non-diabetic adults in fasting and non-fasting state were enrolled. 40 mL of blood was collected from each participant into SST and dipotassium EDTA tubes. Samples were centrifuged immediately or at timed intervals (8, 12, 48 and 72 h). After baseline measurements on the Roche Cobas e602 analyzer using electrochemiluminescence immunoassays, aliquots were stored at room temperature (RT), 2–8 and −20 °C for 4 h to 30 days. The percentage deviation (PD) from baseline was calculated and a change greater than desirable biological variation total error was considered clinically significant.
Results: C-peptide was more stable in separated serum than plasma (PD of −5 vs. −13 %) samples stored at 2–8 °C for 7 days and was most unstable at RT when centrifugation was delayed (PD −46 % in plasma and −74 % in serum after 48 h). Insulin was more stable in plasma than in serum under the different storage conditions with a minimum PD of −1% when stored at −20 °C for 30 days. When samples were kept unspun at RT for 72 h, PD was −23 and −80 % in plasma and serum, respectively.
Conclusions: C-peptide was more stable in serum provided the sample was centrifuged immediately and stored in the fridge or freezer while insulin was found to be more stable in EDTA plasma.