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Welcome to the NWU Repository, the open access Institutional Repository of the North-West University (NWU-IR). This is a digital archive that collects, preserves and distributes research material created by members of NWU. The aim of the NWU-IR is to increase the visibility, availability and impact of the research output of the North-West University through Open Access, search engine indexing and harvesting by several initiatives.

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Recent Submissions

The Failure of African Leaders to Revive the Economy and Alleviate Poverty through the African Union
(E-Journal of Humanities, Arts and Social Sciences, 2024) Marumo, Phemelo Olifile; Motswaledi, Thabang Richard; 30084253
This paper assessed the economic shortfalls of the African leaders in/ through the African Union (AU) in the revival of the African economy and that continues to hinder the continent's development. In doing so, the study employed qualitative techniques. Document analysis was used to illustrate that the African leaders in the organization have not done justice to their goal of being role players economic development of the continent. This has led to the contemporary mediocrity performance of continental economic development. This paper discovered that the economic vision of the African leaders through the AU has not been met thus far. This is a clear indication of the failure of the leaders to meet the organization’s objective in terms ofpoverty alleviation is concerned. The study recommends various mechanisms to enhance Africa’s development through internal trade and economic integration. Hence, it concludes that it is clear that the African Union has not yet achieved its economic objectives. To change this, Africa needs to promote unity and establish itself as a key player in global economic trade, rather than being on the sidelines.
Isolation, screening and biological activity Of Ocotea bullata and Aloe lettyae`s endophytes and metabolites
(North-West University, 2025) Marokane Radebe, CK; Adeleke, RA; Amoo, SO
This study investigated the potential of endophytes from endangered plants to support sustainable agriculture, species conservation efforts, and human health applications, focusing on Ocotea bullata (O. bullata) and Aloe lettyae (A. lettyae). Endophytes, known for synthesizing medicinal, agricultural, and biotechnological metabolites, may provide sustainable solutions for conservation efforts. In addition to the primary focus on the endangered A. lettyae, the study included Aloe longibracteata (A. longibracteata), a closely related non-endangered species, as a comparative model to identify traits beneficial for conservation and stress resilience. Comparative analysis revealed a diverse array of plant growth-promoting metabolites, such as indole-3-acetic acid (IAA) and 5-hydroxy indole-3-acetic acid, with significant implications for species conservation and agricultural applications. Endophytes from both Aloe species, predominantly belonging to the Bacillusmand Enterobacter genera, exhibited key plant growth-promoting traits including: 100% of isolates that fixed nitrogen, 35% that solubilised phosphate, 76% that produced siderophores, and IAA production ranging from 10 to 75 μg/mL. These traits collectively contribute to plant health and stress tolerance. This study also emphasized the importance of sustainable resource utilization, particularly by demonstrating the feasibility of harvesting metabolites from the leaves of the endangered O. bullata. The results showed that the leaves contain a diverse range of metabolites with potential human health applications, including ascorbate, gentisic acid, gallic acid, and chlorogenic acid, providing a sustainable alternative to harvesting the bark and thereby contributing to the protection of the species. Additionally, the endophytes isolated from O. bullata exhibited strong plant growth-promoting properties, including enhancing germination in tomato seeds and exhibiting antimicrobial activity, which could support the plant's health and resilience. The inclusion of A. longibracteata also allowed for the assessment of its potential as a donor of beneficial endophytes for transfer to A. lettyae, offering a novel conservation strategy for the endangered species. Future research should leverage the optimised metabolite extraction methods to explore additional applications while ensuring that the safety of using these Aloe species is thoroughly evaluated. The findings highlight the potential of metabolites derived from these plant species for biofertilizer and biocontrol applications, offering opportunities to develop eco-friendly agricultural solutions while contributing to the preservation of biodiversity.
Equity factor timing framework using the Kalman Filter and Gaussian Hidden Markov Model
(North-West University, 2025) Mashamba, TP; Seitshiro, MB; Seitshiro, I
Factor investment strategies aim to capture persistent risk premia, enhancing risk-adjusted returns over the long term. Traditional approaches, however, provide static exposure and fail to adapt to changing market conditions. Factor timing introduces dynamic adjustments to factor exposures based on expected market trends, with the goal of limiting risk, minimising losses and maximising returns by favouring outperforming factors and avoiding underperforming ones. Although factor timing presents opportunities to exploit market anomalies and inefficiencies, existing literature offers mixed evidence on its effectiveness due to several challenges that includes, knowing when to time factor adjustments during market fluctuations, creating reliable trading signals, accounting for transaction costs, evaluating diversification in dynamic portfolios and limiting the influence of manager’s skill when implementing a factor timing strategy. This study addresses these challenges by using the Kalman filter, ARIMA forecasting, the Hidden Markov model, copula-based diversification analysis, and a hybrid fund of funds approach. The focus is mainly placed on the five most popular factors, namely momentum, value, growth, quality, and size. A momentum factor timing strategy entails a portfolio optimisation process for constructing a large-capitalisation pure momentum portfolio. The process includes a dynamic portfolio construction criterion for selecting stocks, estimated from historical data of the United States of America (US) large-capitalisation stocks from January 2013 to June 2023 and South African (SA) large-capitalisation stocks from January 2013 to June 2024. The Kalman filter is applied to assess historical performance, while ARIMA forecasting estimates expected returns and confidence intervals. The mixture copula models are utilised to determine the dependence structure of a pure momentum portfolio. The portfolio is constructed from a population of large-capitalisation stocks, in which the top 20 stocks with the highest average momentum scores are selected. The value versus growth factor investing framework is assessed and analysed using the US exchange-traded funds (ETFs) from January 2013 to December 2024. A fund of funds is composed of the three largest exchange-traded funds ranked by assets under management, listed in the US. The HMM is used for factor timing. The findings reveal that a dynamic, large-capitalisation momentum portfolio constructed using historical criteria and optimised using a Kalman filter and ARIMA performed well when trading costs were low. Copula analysis revealed that SA momentum portfolios were more diversified than US equivalents. HMM showed value factors recovered faster after market downturns. A combined value and growth fund of funds achieved higher returns than either alone. Comparing Kalman filter and HMM revealed that shorter rebalancing periods improve factor timing effectiveness, suiting active management styles. The HMM outperformed the Kalman filter. It turns out that factor timing can enhance returns by exploiting cyclical factor performance, but effectiveness is constrained by transaction costs and the need for frequent rebalancing. It is recommended that factor timing should complement, rather than replace, static multifactor portfolios. Empirical results show that HMM and Kalman filter methods can theoretically generate profitable trading signals, but practical success depends on cost control and disciplined execution.
Surveillance of ESKAPE pathogens in wastewater environments
(North-West University, 2025) Mabeo, OR; Molale-Tom, LG; Bezuidenhout, CC
Wastewater constitutes a considerable source of environmental contamination, notably as a medium for the proliferation and dissemination of antibiotic-resistant bacteria (ARB) and antibiotic-resistance genes (ARGs). The ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonasaeruginosa, and Enterobacter species) that form part of ARBs are notable for their elevated antibiotic resistance and their common link to severe, frequently hospital-acquired infections, representing a substantial global health risk. The presence of ESKAPE pathogens in the environment constitutes a potential threat to public health, as exposure to these bacteria may result in infections that are challenging to treat due to their intrinsic antibiotic resistance. The One Health Approach necessitates the development of efficient surveillance strategies to prevent and manage the dissemination of ESKAPE pathogens and antibiotic resistance in human, veterinary, and environmental settings. These surveillance strategies have been widely implemented in clinical settings, but few have been implemented in the wastewater environment. In addition, ESKAPE pathogen surveillance in the wastewater environment, especially at wastewater treatment plants (WWTPs) in South Africa, remains unexplored. To contribute towards the One Health Approach, this study aimed to evaluate the presence and characteristics of ESKAPE pathogens in the wastewater environment and to use the data obtained to propose a surveillance programme for the North West and Gauteng provinces of South Africa. The first objective of the study was to compare agar-based enumeration with real-time PCR (RT-PCR) approaches to detecting ESKAPE pathogens in WWTP influent, effluent, and downstream sites. Agar-based enumeration detected all species, while RT-PCR identified only four (E. faecium, S. aureus, K. pneumoniae, and A. baumannii). Enterobacter sp. was most prevalent in agar-based enumeration, while K. pneumoniae was predominant in RT-PCR. Both methods corresponded with high ESKAPE pathogen levels in WWTP influent, gradually decreasing in WWTP effluent. RT-PCR indicated higher downstream ESKAPE pathogen levels than agar-based enumeration. The highest removal efficiency (100%) was observed at some WWTPs, but traces of pathogens remained in downstream sites, indicated by removal efficiency below 99% at WWTPs. The second objective of the study quantified ARGs at WWTP influent, effluent, and downstream sites. Among the six plasmid-mediated AmpC (pAmpC) ARGs, blaMOX had the highest levels, while blaDHA had the lowest. blaMOX was detected in 80% of WWTP effluent and downstream sites. The int1 gene, representing environmental ARGs, was more prevalent than sul1, with 80% detection across all WWTPs. While many WWTPs significantly reduced ARG levels, traces were still discharged into the environment. These findings reinforced concerns that conventional WWTPs cannot fully eliminate antibiotics, ARBs, and ARGs, posing potential risks to receiving water bodies. The third objective of the study was to examine the antibiotic resistance, virulence factors and genomic characteristics of K. pneumoniae from WWTP influent and effluent using culture-based and genomic approaches. β-lactam resistance detected in culture-based tests was confirmed by PCR. Whole genome sequencing (WGS) identified diverse antibiotic resistance genes (ARGs), including ESBLs, and plasmid analysis revealed horizontal gene transfer mechanisms. Virulence genes related to adhesion, biofilm formation, and iron acquisition were also detected. Genomic comparisons showed a shared "core" genome but unique environmental clusters, indicating niche-specific adaptations. These findings emphasized the need for improved surveillance and management to curb antibiotic resistance spread in wastewater ecosystems. The fourth objective of the study was to monitor K. pneumoniae and pAmpC genes at a functional WWTP in the North West province for 12 months. Findings showed positive correlations between K. pneumoniae, pAmpC genes, and physicochemical parameters, indicating their influence on pathogen and ARG presence and dissemination. K. pneumoniae was detected throughout the year, peaking in WWTP influent (June 2021) and WWTP effluent (February 2021), aligning with pAmpC gene trends where blaFOX and blaMOX were most prevalent. While notable reductions were observed (pAmpC genes removal efficiency: 80%–99%, K. pneumoniae removal efficiency: 6%–98%), no reduction occurred in February 2021. This objective confirmed that even well-functioning WWTPs cannot completely eliminate priority pathogens and ARGs, leading to their release into water bodies. In conclusion, the overall findings of this study could be used in policymaking strategies aimed at wastewater-based epidemiology and ESKAPE pathogens surveillance.
Constraining Interacting Dark Energy Models with Cosmological Data
(North-West University, 2025) Thubisi, R. F.; Gidelew, AA; Akalu, SS
In this dissertation, the background of cosmology has been investigated in the framework of the non-gravitational interaction between dark matter and dark energy models (IDE), with the latest cosmological data. Although the initial motivation for the IDE models was to alleviate the coincidence problem, recently, the models have become popular to emphasise the discrepancy between the Hubble measurements from the late- and early-cosmological measurements. We take into account the linear phenomenological models namely: Q = ξHρdm (IDE1), Q = ξHρde (IDE2), and Q = 3ξH(ρdm + ρde) (IDE3); and non-linear models such as Q = 3Hξ ρdmρde ρdm+ρde (IDE4) and Q = 3Hξ√ρdmρde (IDE5) to explore the deviation of each model from the ΛCDM model to systematically investigate the implications of alternative cosmological scenarios. Using baryonic acoustic oscillation data released from the dark energy spectroscopic instrument (BAO DESI), Pantheon+ Supernovae Type Ia combined with SH0ES Cepheid (PantheonP + SH0ES), and cosmic chronometer (CC ) datasets, we constrain the cosmological parameters Ωm, ξ, ω and H0 for each model. Furthermore, we assess the viability of all models compared to ΛCDM by performing the statistical analysis through Bayesian evidence. The results indicate that one of our models, IDE4, remains a better candidate than the other IDE models. Followed by the IDE5, with potential to reduce the H0 tension, making it the second better viable candidate.