The present paper expounds upon the findings of characterization studies conducted on three laterite quarries in Burkina Faso. These quarries have been deemed suitable for utilization in standardized masonry structures. Despite its abundance, the utilization of Laterite Stone (LS) as a construction material in buildings remains underutilized. Consequently, there is an absence of technical data necessary for the design of safe structures. Samples were obtained from both artisanal and mechanized quarries and subsequently submitted to laboratory analysis. A comprehensive study of the physical and mechanical properties has been conducted to dismantle the influence of the geometry of the blocks on the characteristic values, such as the compressive strength and the elastic moduli, according to different standards observed. The objective of this study is twofold: first, to ascertain the viability of this material for low-rise or mid-rise constructions, and second, to examine the impact of anisotropy on the characteristics under investigation. The dimensions of the blocks utilized in this study range from 70×70 mm² to 140×140 mm² for compression tests and from 50×50×300 mm³ to 30×100×350 mm³ for flexural tensile strength tests. The dimensions are reported with a margin of error of approximately 2 millimeters. The mineralogical composition of the LS use is primarily comprised of kaolinite, quartz, and goethite. On the one hand, the findings indicated a substantial variation in the elastic moduli and the modulus of rupture, contingent on the dimensions of the blocks. Conversely, the compressive strength values exhibited approximately 27% higher values when the load was applied in the plane perpendicular to the schistosity beds of the layers as opposed to the plane parallel to it.
Fisheries worldwide exhibit puzzling boom-and-bust cycles despite regulatory efforts, raising questions about what drives these oscillations. We investigate whether temporal delays in monitoring and decision-making contribute to system instability. Our model uses delay differential equations to track an exploiting population and its renewable resources, incorporating two distinct delays: one for perceiving resource status (τ2) and another for implementing management responses (τ1). We establish the existence, uniqueness, and positivity of solutions, then analyze equilibrium stability through linearization and Lyapunov–Razumikhin functions. The characteristic equation reveals Hopf bifurcations at critical delay thresholds. Numerical simulations across 1600 parameter combinations using MATLAB R2023b’s DDE23 algorithm quantify these transitions. The results show a critical threshold near 1.64 years (20 months): below this value, systems converge to a stable equilibrium, while above it, persistent oscillations emerge within 20–26 year periods. Unexpectedly, one large delay destabilizes less than two moderate delays summing to the same total, contradicting uniform improvement strategies. Convergence to limit cycles requires roughly 40 years, exceeding typical management horizons and potentially masking true system dynamics. The critical threshold lies within realistic administrative timescales, suggesting that institutional delays may substantially contribute to observed population fluctuations. These findings indicate that accelerating either monitoring or decision processes rather than providing modest improvements to both could better stabilize exploited resources.
Background: Diarrhea accounts for nearly one in five child deaths, with approximately 1.5 million annual fatalities, mainly in peri-urban and rural settings with poor living conditions. This study assessed environmental and household Behavioral factors associated with childhood diarrhea in Maluku I. Methods: A cross-sectional study was conducted in 239 households with children aged 0–59 months. Data were collected using structured questionnaires and analyzed using logistic regression, with associations expressed as odds ratios (ORs) and p-values (<0.05). Results: The prevalence of childhood diarrhea was 21.3%. Households with clean yards showed an 11-fold lower risk (OR = 0.09; 95% CI: 0.01–0.88; p = 0.039), whereas access to improved water reduced the risk by 7.7-fold (OR = 0.13; 95% CI: 0.11–0.29; p < 0.001). Lack of handwashing at critical times emerged as the strongest risk factor, increasing the likelihood of diarrhea approximately six-fold (OR = 6.13; 95% CI: 2.09–18.00; p < 0.001). Conclusion: Childhood diarrhea in Maluku I remains highly prevalent and is strongly influenced by modifiable environmental and behavioral factors, highlighting the need for targeted interventions.
The review discusses the advancements in vermifiltration research over the last decade, focusing on pollution removal mechanisms, system performance, the fate of filter components, and by-products. Vermifiltration has demonstrated remarkable capabilities, particularly in treating highly contaminated wastewater with Chemical Oxygen Demand (COD) levels exceeding 92,000 mg/L and Biochemical Oxygen Demand (BOD5) levels over 25,000 mg/L, achieving removal rates of approximately 89% and 91%, respectively. Importantly, vermifiltration maintains its effectiveness even with fluctuating organic loads at the inlet, thanks to optimization of parameters like Hydraulic Loading Rate, biodegradable organic strength, earthworm density and active layer depth. Clogging issues can be minimized through parameters optimization. The review also highlights vermifiltrations’ potential in co-treating the organic fraction of municipal solid waste while significantly reducing heavy metal concentrations, including Cd, Ni, Pb, Cu, Cr, and Zn, during the treatment process. Earthworms play a pivotal role in the removal of various components, with impressive removal percentages, such as 75% for Total Organic Carbon (TOC), 86% for Total COD, 87% for BOD5, 59% for ammonia nitrogen, and 99.9% for coliforms. Furthermore, vermifiltration-treated effluents can be readily utilized in agriculture, with the added benefit of producing vermicompost, a nutrient-rich biofertilizer. The technology contributes to environmental sustainability, as it helps reduce greenhouse gas emissions (GHG), thanks to earthworm activity creating an aerobic environment, minimizing GHG production compared to other wastewater treatment methods. In terms of pollutant degradation modeling, the Stover-Kincannon model outperforms the first-order and Grau second-order models, with higher regression coefficients (R2 = 0.9961 for COD and R2 = 0.9353 for TN). Overall, vermifiltration emerges as an effective and sustainable wastewater treatment solution, capable of handling challenging wastewater sources, while also producing valuable by-products and minimizing environmental impacts.
To estimate differential settlements of building foundation soils, the site on which the structure is based must be geotechnically surveyed in order to determine the deformation parameters and the thickness of the compressible soil layers in various places. This involves conducting destructive surveys. In this study, the use of geophysical methods (electrical soundings) as a substitute for the conventional methods used was considered. The Schlumberger electrodes array was deployed at the level of a control borehole and at three projected footings. The combination of the results of the electrical soundings with the lithological section of the borehole reveals a significant correlation between the variations of cumulative resistivities and the lithological section of the subsoil. The thickness of the compressible layers at the level of the projected footings is estimated to vary between 5 and 6 m. Œdometric differential settlements have an estimated maximum value of 4.56 cm
