Baze University

The migration of contaminants through inactive supply wells (ISWs) has drawn significant scrutiny because these wells can act as preferential flow pathways for contaminant transfer between aquifers. Declines in groundwater levels and clogging around ISWs can significantly reduce flow rates through these wells. Moreover, these wells can be surrounded by a finite-thickness skin, such as a gravel pack, and physical and biochemical clogs. Nevertheless, the impacts of fluctuating flow rates and the presence of a skin zone on contaminant migration through ISWs have not been exhaustively investigated. This study addresses this critical gap by initially fitting observational data from fieldwork carried out in California, USA, to characterize the variability in flow rates. Subsequently, a semi-analytical model incorporating both variable flow rates and skin effects was developed to elucidate contaminant migration. When benchmarked against a numerical solution, the approach exhibited superior accuracy and robustness. Several noteworthy findings emerged. First, the proposed exponential function precisely captures the variability in flow rates. Second, even minor alterations in the power index λ lead to substantial changes in breakthrough curves (BTCs), underscoring the high sensitivity of contaminant migration to variable flow rates. Third, increased dispersivity or reduced effective porosity within the skin zone accelerates contaminant migration. Furthermore, the contrast in dispersivity between the skin and aquifer leads to sharp changes in the spatial distribution of contaminants at their interface, which affects contaminant migration potential. Thus, variations in flow rates and skin effects profoundly influence contaminant migration through ISWs and must be rigorously considered in cross-contamination assessments.

To support the global transition from fossil fuel to cleaner energy sources, this study conducts the techno-economic analyses of four hybrid energy systems: Grid/photovoltaic (PV)/Hydro, PV/Hydro, Grid/Hydro, and Grid/PV for sustainable rural electrification in Nigeria. While hybrid energy systems using solar PV, wind, and diesel have attracted credible attention, this work highlights the untapped potential of run-of-river hydro-power, a carbon-free resource with widespread networks across the globe. The analyses using the HOMER pro software tool incorporated the incessant utility grid interruption characteristics of developing countries. Results reveal that the hybrid Grid/PV/Hydro system is optimal in meeting the community’s electricity demand of 2,822.20 kWh/day at the lowest net present cost of 9,160,308.00 and levelized cost of energy of0.13/kWh. The micro-hydro power plants, solar PV, and grid, respectively, contribute 80.90

Health economics is crucial for optimizing resource allocation and achieving equitable health outcomes in Africa. This study reviewed the historical evolution and current state of health economics in Africa, focusing on healthcare financing mechanisms, resource allocation strategies, and policy interventions. Data from peer-reviewed articles, research reports, and grey literature were synthesized from databases like PubMed, Scopus, Google Scholar and African Journals Online (AJOL). While healthcare financing dominated the literature, this review also covers resource allocation and broader health economics, highlighting key gaps in African research. Findings highlight significant challenges such as low public expenditure, high out-of-pocket costs, and inadequate insurance coverage. Out-of-pocket payments constitute over 40

This study presents a novel compartmental mathematical model for analyzing crime and corruption within socio-political systems, with a focus on Colombia, Guatemala, and Venezuela. Recognizing the mutually reinforcing nature of crime and corruption, the model incorporates key population compartments: vulnerable citizens, law enforcement, exposed individuals, corrupt agents, persistent criminals, prosecuted individuals, and those in correctional institutions. A system of nonlinear differential equations captures the dynamic transitions between these states, driven by socio-institutional and behavioral parameters. Qualitative analysis establishes the model’s positivity, boundedness, and equilibria analysis, while the basic reproduction number ℛ_0 is derived using the next-generation matrix method to assess the threshold conditions for persistence or eradication of corruption and crime. The model is calibrated using empirical data from the United Nations Office on Drugs and Crime (UNODC), with country specific simulations revealing divergent trajectories. Results indicate that high transition into corruption and low prosecution rates exacerbate systemic corruption, particularly in Guatemala. In contrast, Colombia’s strong enforcement and moderate transition rates yield better containment. Venezuela presents an intermediate case, with early gains diminishing over time. Policy simulations suggest that increasing prosecution and sentencing rates significantly reduce long-term corruption prevalence.

This study examines strategies for improving cost performance through effective internal stakeholder management in building construction projects in Nigeria. Despite the critical role of stakeholder management in project success, limited empirical research exists on specific strategies that enhance cost outcomes in the Nigerian construction context. Anchored on stakeholder theory and the resource-based view, this study evaluates stakeholder management strategies across five dimensions: stakeholder identification and analysis, communication and information sharing, trust and expectation management, conflict resolution and collaboration, and continuous improvement and feedback mechanisms. A quantitative survey research design was employed, with data collected from 106 construction professionals in North-Western Nigeria using structured questionnaires. Data were analyzed using descriptive statistics (mean scores, standard deviations, Relative Importance Index) and multiple regression analysis with comprehensive diagnostic testing. The findings reveal that trust between departments (RII = 0.745), consistency and transparency in decision-making (RII = 0.769), stakeholder participation in decision-making (RII = 0.759), and timely communication of project updates (RII = 0.745) are the most effective strategies for improving cost performance. Regression analysis, validated through multicollinearity diagnostics (VIF < 10) and stepwise regression, identified six significant predictors, with trust between departments (β = 7.852, p = 0.009), consistency in decision-making (β = 4.126, p = 0.025), and timely communication (β = 4.069, p = 0.026) as the strongest positive predictors. The study concludes that structured stakeholder management practices significantly enhance cost performance and recommends the adoption of systematic stakeholder identification tools, transparent communication protocols, collaborative decision-making processes, and continuous feedback mechanisms in Nigerian building construction projects.