1. Academic Wits Research Publications (Faculties submissions)
Permanent URI for this communityhttps://hdl.handle.net/10539/37774
Browse
16 results
Search Results
Item Batch and semi-continuous fermentation with Parageobacillus thermoglucosidasius DSM 6285 for H2 production(BMC, 2025) de Maayer, Pieter; Ardila, Magda S.; Aliyu, Habibu; Neumann, AnkeBackground Parageobacillus thermoglucosidasius is a facultatively anaerobic thermophile that is able to produce hydrogen (H2) gas from the oxidation of carbon monoxide through the water–gas shift reaction when grown under anaerobic conditions. The water–gas shift (WGS) reaction is driven by a carbon monoxide dehydrogenase– hydrogenase enzyme complex. Previous experiments exploring hydrogenogenesis with P. thermoglucosidasius have relied on batch fermentations comprising defned media compositions and gas atmospheres. This study evaluated the efects of a semi-continuous feeding strategy on hydrogenogenesis. Results A batch and two semi-continuous fermentations, with feeding of the latter fresh media (with glucose) in either 24 h or 48 h intervals were undertaken and H2 production, carbon monoxide dehydrogenase (CODH) activity, and metabolite consumption/production were monitored throughout. Maximum H2 production rates (HPR) of 0.14 and 0.3 mmol min−1, were observed for the batch and the semi-continuous fermentations, respectively. Daily feeding attained stable H2 production for 7 days, while feeding every 48 h resulted in high variations in H2 production. CODH enzyme activity correlated with H2 production, with a maximum of 1651 U mL−1 on day 14 with the 48 h feeding strategy, while CODH activity remained relatively constant throughout the fermentation process with the 24 h feeding strategy. Conclusions The results emphasize the signifcance of a semi-continuous glucose-containing feed for attaining stable hydrogen production with P. thermoglucosidasius. The semi-continuous fermentations achieved a 46% higher HPR than the batch fermentation. The higher HPRs achieved with both semi-continuous fermentations imply that this approach could enhance the biohydrogen platform. However, optimizing the feeding interval is pivotal to ensuring stable hydrogen production.Item New modern and Pleistocene fossil micromammal assemblages from Swartkrans, South Africa: Paleobiodiversity, taphonomic, and environmental context(Elsevier, 2024-03) Steininger, Christine; Clarke, Ronald J.; Caruana, Matthew V.; Kuman, Kathleen; Pickering, Travis Rayne; Linchamps, Pierre; Stoetzel, Emmanuelle; Amberny, LaurieThe oldest deposit at the hominin-bearing cave of Swartkrans, South Africa, is the Lower Bank of Member 1, dated to ca. 2.2 million years ago. Excavations of this unit have produced a diverse and extensive mammalian fossil record, including Paranthropus robustus and early Homo fossils, along with numerous Oldowan stone tools. The present study focuses on the taxonomic analysis of the micromammalian fossil assemblage obtained from recent excavations of the Lower Bank, conducted between 2005 and 2010, as part of the Swartkrans Paleoanthropological Research Project. The taxonomic composition of this assemblage is dominated by Mystromys, a rodent indicative of grassland environments. Taphonomic analysis indicates an accumulation of prey by Tyto alba (Barn owl) or a related species. Environments inferred from this evidence reflect an open landscape primarily covered by grassland vegetation, but they also feature components of wooded areas, rocky outcrops, and the proximity of a river. The Swartkrans fossil assemblage is compared with Cooper's D (dated to ca. 1.4 Ma) and a modern coprocoenosis of Bubo africanus (spotted eagle-owl) collected within the Swartkrans cave for taxonomic, taphonomic, and paleoecological perspectives. Contrasting fossil and modern micromammalian data provide a better understanding of accumulation processes and facilitate a diachronic reconstruction of changes in climate and landscape evolution. Issues regarding paleoenvironmental reconstruction methodologies based on micromammals are also discussed.Item Time and frequency nexus among public debt, exchange rate, inflation, monetary policy rate and economic growth in Ghana(Elsevier, 2025-01) Owusu Junior, Peterson; Odoom, Absalom; Adu-Asare Idun, Anthony; Akorsu, Patrick KwashieThe debate about the influence of public debt on an economy has gained long-standing attention among policy-makers, regulators and academic scholars. The excessive expansion of Ghana’s public debt to GDP demands a fresh insight into the macroeconomic variables that are connected to economic growth. This study utilised wavelet techniques to investigate the nexus and effect of public debt, exchange rate, inflation rate, and monetary policy rate on economic growth in Ghana using monthly data from 2000 to 2022. Diks and Panchenko (2006) was used as a battery test for the wavelet results. We found a significant negative correlation between public debt and GDP at both short- and long-term frequencies, though there was no notable connection in the medium term. The causality analysis suggests a possibility of bidirectional causality between GDP and public debt in both the short and medium term. Interestingly, the COVID-19 pandemic had minimal impact on this relationship when comparing the pre-pandemic and during-pandemic periods. The only observed coherence (negative) between monetary policy and GDP occurred between 2000 and 2003, at low and medium frequencies. The WMCC results depicted that no variable was seen to lead or lag during the pandemic period however, GDP (exchange rate) reacted to shocks first (last) in the short run (long run) prior to the pandemic. The result of this research is crucial for policy implementation. The GDP-public debt negative nexus offers strong evidence for the government to make determined efforts to reduce external borrowing. The positive coherence of exchange rates and the public debt offers a strong incentive to the monetary authorities to make determined efforts to stop the rapid rise of exchange rates.Item Mobile Technology use in clinical research examining challenges and implivations for health promotion in South Africa: mixed methods study(JMIR Publications, 2024) Norris, Shane A.; Mabetha, Khuthala; Soepnel, Larske M.; Mabena, Gugulethu; Motlhathedi, Molebogeng; Nyathi, Lukhanyo; Draper, Catherine E.Background: The use of mobile technologies in fostering health promotion and healthy behaviors is becoming an increasingly common phenomenon in global health programs. Although mobile technologies have been effective in health promotion initiatives and follow-up research in higher-income countries and concerns have been raised within clinical practice and research in low- and middle-income settings, there is a lack of literature that has qualitatively explored the challenges that participants experience in terms of being contactable through mobile technologies. Objective: This study aims to explore the challenges that participants experience in terms of being contactable through mobile technologies in a trial conducted in Soweto, South Africa. Methods: A convergent parallel mixed methods research design was used. In the quantitative phase, 363 young women in the age cohorts 18 to 28 years were contacted telephonically between August 2019 and January 2022 to have a session delivered to them or to be booked for a session. Call attempts initiated by the study team were restricted to only 1 call attempt, and participants who were reached at the first call attempt were classified as contactable (189/363, 52.1%), whereas those whom the study team failed to contact were classified as hard to reach (174/363, 47.9%). Two outcomes of interest in the quantitative phase were "contactability of the participants" and "participants' mobile number changes," and these outcomes were analyzed at a univariate and bivariate level using descriptive statistics and a 2-way contingency table. In the qualitative phase, a subsample of young women (20 who were part of the trial for ≥12 months) participated in in-depth interviews and were recruited using a convenience sampling method. A reflexive thematic analysis approach was used to analyze the data using MAXQDA software (version 20; VERBI GmbH). Results: Of the 363 trial participants, 174 (47.9%) were hard to reach telephonically, whereas approximately 189 (52.1%) were easy to reach telephonically. Most participants (133/243, 54.7%) who were contactable did not change their mobile number. The highest percentage of mobile number changes was observed among participants who were hard to reach, with three-quarters of the participants (12/16, 75%) being reported to have changed their mobile number ≥2 times. Eight themes were generated following the analysis of the transcripts, which provided an in-depth account of the reasons why some participants were hard to reach. These included mobile technical issues, coverage issues, lack of ownership of personal cell phones, and unregistered number. Conclusions: Remote data collection remains an important tool in public health research. It could, thus, serve as a hugely beneficial mechanism in connecting with participants while actively leveraging the established relationships with participants or community-based organizations to deliver health promotion and practice.Item Antecedents of attitudes towards the use of environmentally friendly household applicance products in Zimbabwe An extension of the theory of planned behaviour(Emerald Publishing Limited, 2023) Maziriri, E.T.; Nyagadza, Brighton; Chuchu, Tinashe; Mazuruse, GideonPurpose– This study aims to determine the antecedents that influence attitudes towards the use of environmentally friendly household appliance products and consumers’ green purchase intention among consumers in Harare, Zimbabwe. Design/methodology/approach– Data were collected from 329 consumers in Harare, Zimbabwe’s commercial capital who were served fromfive using a structured questionnaire via an online web-based crosssectional survey. Hypothesised relationships were tested throughstructural equation modellingwith the aid of Smart PLS software. Findings– Green product awareness, social influence, perceived benefit and attitude towards green appliances were found to have a significant positive effect on green purchase intention. Research limitations/implications– The study’s findings may not be generalised to other contexts as sample data was only collected in Zimbabwe. Complementary cross-sectional research studies can be done in other parts of the world to enable cross-cultural comparisons and methodological validations.Item Mobile technology use in clinical research examining challenges and implications for health promotion in South Africa: mixed methods study(JMIR Publications, 2024-04) Norris, Shane A.; Cohen, Emmanuel; Slemming, Wiedaad; Wrottesley, Stephanie V.; Prioreschi, AlessandraBackground: The use of mobile technologies in fostering health promotion and healthy behaviors is becoming an increasingly common phenomenon in global health programs. Although mobile technologies have been effective in health promotion initiatives and follow-up research in higher-income countries and concerns have been raised within clinical practice and research in lowand middle-income settings, there is a lack of literature that has qualitatively explored the challenges that participants experience in terms of being contactable through mobile technologies. Objective: This study aims to explore the challenges that participants experience in terms of being contactable through mobile technologies in a trial conducted in Soweto, South Africa. Methods: A convergent parallel mixed methods research design was used. In the quantitative phase, 363 young women in the age cohorts 18 to 28 years were contacted telephonically between August 2019 and January 2022 to have a session delivered to them or to be booked for a session. Call attempts initiated by the study team were restricted to only 1 call attempt, and participants who were reached at the first call attempt were classified as contactable (189/363, 52.1%), whereas those whom the study team failed to contact were classified as hard to reach (174/363, 47.9%). Two outcomes of interest in the quantitative phase were “contactability of the participants” and “participants’ mobile number changes,” and these outcomes were analyzed at a univariate and bivariate level using descriptive statistics and a 2-way contingency table. In the qualitative phase, a subsample of young women (20 who were part of the trial for ≥12 months) participated in in-depth interviews and were recruited using a convenience sampling method. A reflexive thematic analysis approach was used to analyze the data using MAXQDA software (version 20; VERBI GmbH). Results: Of the 363 trial participants, 174 (47.9%) were hard to reach telephonically, whereas approximately 189 (52.1%) were easy to reach telephonically. Most participants (133/243, 54.7%) who were contactable did not change their mobile number. The highest percentage of mobile number changes was observed among participants who were hard to reach, with three-quarters of the participants (12/16, 75%) being reported to have changed their mobile number ≥2 times. Eight themes were generated following the analysis of the transcripts, which provided an in-depth account of the reasons why some participants were hard to reach. These included mobile technical issues, coverage issues, lack of ownership of personal cell phones, and unregistered number. Conclusions: Remote data collection remains an important tool in public health research. It could, thus, serve as a hugely beneficial mechanism in connecting with participants while actively leveraging the established relationships with participants or community-based organizations to deliver health promotion and practice.Item A qualitative analysis of community health worker perspectives on the implementation of the preconception and pregnancy phases of the Bukhali randomised controlled trial(Public Library of Science, 2024) Norris, Shane A.; Soepnel, Larske M.; Mabetha, Khuthala; Motlhatlhedi, Molebogeng; Nkosi, Nokuthula; Lye, Stephen; Draper, Catherine E.Community health workers (CHWs) play an important role in health systems in low- and middle- income countries, including South Africa. Bukhali is a CHW-delivered intervention as part of a randomised controlled trial, to improve the health trajectories of young women in Soweto, South Africa. This study aimed to qualitatively explore factors influencing implementation of the preconception and pregnancy phases of Bukhali, from the perspective of the CHWs (Health Helpers, HHs) delivering the intervention. As part of the Bukhali trial process evaluation, three focus group discussions were conducted with the 13 HHs employed by the trial. A thematic approach was used to analyse the data, drawing on elements of a reflexive thematic and codebook approach. The following six themes were developed, representing factors impacting implementation of the HH roles: interaction with the existing public healthcare sector; participant perceptions of health; health literacy and language barriers; participants’ socioeconomic constraints; family, partner, and community views of trial components; and the HH-participant relationship. HHs reported uses of several trial-based tools to overcome implementation challenges, increasing their ability to implement their roles as planned. The relationship of trust between the HH and participants seemed to function as one important mechanism for impact. The findings supported a number of adaptations to the implementation of Bukhali, such as intensified trial-based follow-up of referrals that do not receive management at clinics, continued HH training and community engagement parallel to trial implementation, with an increased emphasis on health-related stigma and education. HH perspectives on intervention implementation highlighted adaptations across three broad strategic areas: navigating and bridging healthcare systems, adaptability to individual participant needs, and navigating stigma around disease. These findings provide recommendations for the next phases of Bukhali, for other CHW-delivered preconception and pregnancy trials, and for the strengthening of CHW roles in clinical settings with similar implementation challenges.Item Explainable early prediction of gestational diabetes biomarkers by combining medical background and wearable devices: a pilot study with a cohort group in South Africa(Institute of Electrical and Electronics Engineers, 2024) Norris, Shane; Kolozali, Sefki; White, Sara L.; Fasli, Maria; van Heerden, AlastairThis study aims to explore the potential of Internet of Things (IoT) devices and explainable Artificial Intelligence (AI) techniques in predicting biomarker values associated with GDM when measured 13–16 weeks prior to diagnosis. We developed a system that forecasts biomarkers such as LDL, HDL, triglycerides, cholesterol, HbA1c, and results from the Oral Glucose Tolerance Test (OGTT) including fasting glucose, 1-hour, and 2-hour postload glucose values. These biomarker values are predicted based on sensory measurements collected around week 12 of pregnancy, including continuous glucose levels, short physical movement recordings, and medical background information. To the best of our knowledge, this is the first study to forecast GDM-associated biomarker values 13 to 16 weeks prior to the GDM screening test, using continuous glucose monitoring devices, a wristband for activity detection, and medical background data. We applied machine learning models, specifically Decision Tree and Random Forest Regressors, along with Coupled-Matrix Tensor Factorisation (CMTF) and Elastic Net techniques, examining all possible combinations of these methods across different data modalities. The results demonstrated good performance for most biomarkers. On average, the models achieved Mean Squared Error (MSE) between 0.29 and 0.42 and Mean Absolute Error (MAE) between 0.23 and 0.45 for biomarkers like HDL, LDL, cholesterol, and HbA1c. For the OGTT glucose values, the average MSE ranged from 0.95 to 2.44, and the average MAE ranged from 0.72 to 0.91. Additionally, the utilisation of CMTF with Alternating Least Squares technique yielded slightly better results (0.16 MSE and 0.07 MAE on average) compared to the well-known Elastic Net feature selection technique. While our study was conducted with a limited cohort in South Africa, our findings offer promising indications regarding the potential for predicting biomarker values in pregnant women through the integration of wearable devices and medical background data in the analysis. Nevertheless, further validation on a larger, more diverse cohort is imperative to substantiate these encouraging results.Item Young women’s social support networks during pregnancy in Soweto, South Africa(OASIS, 2024-04) Norris, Shane A.; Mabetha, Kuthala; Soepnel, Larske M.; Klingberg, Sonja; Mabena, Gugulethu; Motlhatlhedi, Molebogeng; Draper, Catherine E.Background: Although studies from high-income countries have examined social support during pregnancy, it remains unclear what type of support is received by expectant mothers from low- and middle-income country settings. Aim: To explore young women’s social support networks during pregnancy in Soweto, South Africa. Setting: This study was undertaken in an academic hospital based in the Southwestern Townships (Soweto), Johannesburg, in Gauteng province, South Africa. Methods: An exploratory descriptive qualitative approach was employed. Eighteen (18) young pregnant women were recruited using a purposive sampling approach. In-depth interviews were conducted, and data were analysed using inductive thematic analysis. Results: Analysis of the data resulted in the development of two superordinate themes namely; (1) relationships during pregnancy and (2) network involvement. Involvement of the various social networks contributed greatly to the young women having a greater sense of potential parental efficacy and increased acceptance of their pregnancies. Pregnant women who receive sufficient social support from immediate networks have increased potential to embrace and give attention to pregnancy-related changes. Conclusion: Focusing on less-examined characteristics that could enhance pregnant women’s health could help in the reduction of deaths that arise because of pregnancy complications and contribute in globally accelerating increased accessibility to adequate reproductive health. Contribution: This study’s findings emphasise the necessity for policymakers and healthcare providers to educate the broader community about the importance of partner, family and peer support to minimise risks that may affect pregnancy care and wellbeing of mothers.Item Corporate financialisation: a conceptual clarification and critical review of the literature(Southern Centre for Inequality Studies, 2024-05) Reddy, Niall; Rabinovich, JoelCorporate financialisation (CF) comprises a major field of financialisation studies centred on the belief that significant changes in corporate governance and business models have been driven by financial imperatives, which have had a profound impact on investment habits, labour policies, organisational practices and the distribution of revenues. Experiencing explosive growth in recent years, this field has become mired in conceptual ambiguity, mirroring problems with financialisation studies as a whole. While seeking to restore some conceptual clarity and clearly delineate the boundaries of the concept, this paper offers a detailed review of empirical work on CF. At the core of the field, we identify four sub-theories, each addressing distinct aspects of the way business models have become financialised under the influence of shareholder value principles. Our dissection of the literature shows, however, that these theories mostly remain under-substantiated. The connection of financialisation strategies to key outcomes of interest, such as declining investment and rising inequality, remains nebulous in most cases. Beyond this, we identify key weaknesses in the way shareholder value orientation – the causal lynch pin of CF accounts – has been theorised. The field as a whole has paid insufficient attention to the variegated and uneven nature of the shareholder revolution, which has prevented a single uniform set of governance principles from diffusing. We also argue that the tendency to dilute definitions of corporate financialisation across explanans and explanandum has masked problems of verification. The critique concludes with a call for conceptual clarity and more care in distinguishing financialisation from causal channels associated with other structural dynamics, such as monopolisation.