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ItemA statistical comparison of finite Time Lyapunov exponents and Okubbo-Weiss parameter(Makerere University, 2026)In this study, we have investigated stirring and mixing properties of particle transport by analyzing the statistical moments from PDFs of Okubbo-Weiss (OW) or Finite time lyapunov exponet (FTLE) diagnostics. In contrast with OW metric, FTLE tools have the advantage of exploiting both spatial and temporal variability of the velocity field and are in principle able to unveil subgrid filaments generated by chaotic stirring. However, one may wonder whether why this statistical advantage is of practical interest in real-data, mesoscale and sub-mesoscale analysis, because of the uncertainties from resolution and binning of data. Here we have compared the ability of OW and the FTLE statistics in detecting transport and mixing properties in fluid flows. By considering two examples of geophysical interest the meandering jet flow and ABC steady flow, we found that the two approaches provide similar results for slowly evolving vortices at early times. However, the FTLE was also able to predict the filamentary processes. Such filaments were also observed, with some mismatch in the two velocity fields, didn’t show any compact relation with other OW diagnostic. It has been found that the OW is a limiting case of the FTLE, Probability distribution functions (PDFs) of FTLEs and OW are computed to better understand implications for mixing and stirring. The study of the shape of the PDFs and their sensitivity, or lack thereof, to whether the FTLE or OW is computed based on 2D or 3D flows allowed us to make inferences about the nature of mixing and stirring. The probability distribution functions (PDFs) are found to be non Gaussian. The nonGaussianity of these PDFs suggests that parameterization schemes in existing numerical models should be improved.
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ItemAssessment of pesticide residues from herbal medicines sold in selected markets in Kampala District, Uganda(Makerere University, 2025)The growing reliance on herbal medicines in Uganda, especially in Kampala District's urban areas, has raised safety concerns due to potential pesticide contamination. This study evaluated pesticide residue levels in herbal medicines sold in four major markets (Kalerwe, Usafi, Owino, and Nakasero) in Kampala District and evaluated the associated health risks through consumption of pesticide-contaminated herbal medicines. A total of 64 herbal medicine samples (48 liquid and 16 solid formulations) were analysed. Samples were extracted using solvent-based techniques (acetonitrile for liquids and a mixture of n-hexane/dichloromethane for solids), cleaned with Florisil-packed columns, and analyzed using gas chromatography-mass spectrometry (GC-MS) for 31 pesticides of various chemical groups (organochlorines, OCPs; organophosphates, OPPs; herbicides; other pesticides, namely cypermethrin, quinoxyfen, and cybutryne). Pesticide levels in liquid samples ranged from 1.20 to 306.07µg kg⁻¹ f.w., with the total mean of 96.89 µg kg⁻¹ f.w. OCPs were the most predominant pesticides (45.1% of the total pesticides), followed by others (23.2%). For solid samples, pesticide concentrations varied from 0.36 to 307.34 µg kg⁻¹ d.w., with the total mean of 162.11 µg kg⁻¹ d.w. The herbal medicines from Nakasero market had the highest total mean concentrations (148.9 µg kg⁻¹), followed by Owino (112.60 µg kg⁻¹). Endrin-aldehyde was the most frequently detected pesticide (98.4% of the samples), while hexachlorobenzene was the least detected (14.1%). In general, the pesticide levels were below the limits set by the World Health Organization (WHO), Food and Agriculture Organization (FAO), and Codex Alimentarius Commission for herbal products. Most of the samples had HQ and HI values
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ItemImpact of depositional architecture on petroleum reservoir quality of South Lake Albert Basin, Western Uganda(Makerere University, 2026)Depositional environments and architectures’ interpretations and analyses were carried out in the South Lake Albert Basin to map out depositional environments and their associated architectures with the main objective of establishing the impact of depositional architecture on the petroleum reservoir quality within the stratigraphic section, Late Miocene to Late Pliocene stratigraphic interval (11.6 ma to 5.3 ma). Structural modelling was conducted to generate depth structural maps to guide the development of zoned models. In addition, facies and petroleum reservoir property modelling, geological sampling and stratigraphic logging were undertaken to evaluate petroleum reservoir properties and depositional environments with their associated architectures. Thin section analysis was conducted on cored and field samples to investigate spatial and stratigraphic distribution of porosity and permeability. The results indicate that South Lake Albert Basin is comprised of structural compartments, pinchouts, flower structures, folds, a fault that makes a terrace in the basin, and a basin bounding fault in the Kaiso-Tonya area, normal faults with limited displacements and a basin bounding fault in the Kingfisher area. Sediments were also found to be highly intercalated. Alluvial fans, fluvial, deltaic and lacustrine depositional environments with associated depositional architectures are found. Petroleum reservoir quality in both Kaiso-Tonya and Kingfisher areas was found to be very low to high. Sections that are close to the basin bounding fault for both Kaiso-Tonya and Kingfisher areas consist of alluvial fan and fluvial depositional environments and have low to moderate petroleum reservoir quality. The section that is close to the lake and under the lake consists of deltaic and lacustrine depositional environments and has moderate to high petroleum reservoir quality. The results found that compartmentalization, pinchouts and intercalations and facies heterogeneity of sediments, and all other identified architectural elements influence the petroleum reservoir quality. They found that these identified architectural elements have a high effect on the connectivity, fluid saturation and flow, and delineation/extent of the reservoir continuity. Structural compartments stacked or intercalated sediments, pinchouts lead to reduced connectivity within sediments. They further contribute to the uncertainty in reservoir continuity, stacked petroleum reservoirs with undefined lateral extent and the low to moderate petroleum reservoir quality. The study further developed a petroleum reservoir quality predictive model that will guide future petroleum exploitation programs within the study area and basins with similar sedimentological and structural settings.
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ItemMineralogical and geochemical characterization of Nyamuliro Wolfram Mine Tailings, Rubanda District, Southwestern Uganda(Makerere University, 2026)Nyamuliro Wolfram Mine is located in Rubanda District, Southwestern Uganda in the Akanyaru Ankole Supergroup geological formation. The selective mining methods used in Nyamuliro has generated huge volumes of tailings since 1970s. The artisanal and small-scale mining activities. Mineralogical characterization using X-ray Diffraction show that Nyamuliro wolfram mine tailings have several mineral types of quartz, alite, huanzalit, piemontite, halloysite, sanmartinite, muscovite, lizardite and pyromangite. Petrological analysis shows presence quartz, wolframite, pyrite, chalcopyrite, arsenopyrite and some sphalerite, ilmenite and gold. The geochemical characteristics of the tailings show a high concentration of wolfram (5.39-46.94 wt%) iron (27.54 to 64.97wt%, titanium (2.96 to 9.45 wt% for mine tailings and 2.22 to 6.18 wt% for metallurgical tailings) yttirium concentrations (0.10 to 0.66 wt% for mine tailings and 0.06 to 0.28 wt% for metallurgical tailings). Also in detectable amounts are other critical elements such as Nb, Ta, Zn, Pb,As and Hg. The high quartz content of the tailings makes them suitable for the manufacture of ceramics, cement and other industrial applications. The results also show that Nyamuliro wolfram tailings are viable secondary resources for wolfram and other critical metals including iron and gold. The presence of sulphide minerals and high concentration of heavy metals requires that the tailings are properly managed to avoid exposure that can lead to environmental pollution through acid mine drainage and release of heavy metals. The shaking table and process fines are likely harboring most of the heavy metals and critical metals. Recovering wolfram and other critical metals and minerals from these tailings at a profit will in turn provide solution for difficulty engineering and risks of slope collapse. It will also provide a robust plan to manage the formation of acid mine drainage and minimize the contamination of water bodies and soil within the mining communities.
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ItemGenesis and distribution of gold deposits in Nyakishenyi Village, Buhweju District, Southwestern Uganda(Makerere University, 2026)This study investigates the genesis and spatial distribution of gold deposits in Nyakishenyi Village, Buhweju District, South Western Uganda, with the main aim of understanding the structural and geochemical controls of orogenic gold systems. The study area is found within the Proterozoic Kibaran Belt and this region represents a geologically significant yet underexplored segment of Uganda’s Precambrian terranes. Quartz veins within schists, quartzites, and granitoid contacts host the primary gold deposits, with NW–SE and NE–SW trending shear zones and faults acting as key fluid pathways. Primary gold mineralization is concentrated at lithological boundaries and fault –fault intersections, reinforced by elevated pathfinder elements ( e.g As, Sb, Cu, W)confirming an orogenic origin. Secondary placer deposits in colluvial zones and stream channels represent erosional derivatives of the primary lodes. GIS modeling exposed strong links between fault density, structural intersections, geochemical anomalies, and artisanal mining spots. Quartz veins reverted peak gold gradesof1.65 ounces per ton. averaging 0.5–1.2 ounces per ton. in shear zones, while placer deposits generated 0.3–0.8 g/t, indicating secondary enrichment. High-grade zones averaged2.5faults/km², with mineralization hotspots concentrated at fault intersections and lithological contacts between schists, quartzites, and granitoids. Elevated pathfinder elements (As, Sb, Cu, W) frequently align with high gold values (>1.5oz/t), while major oxides (Fe₂O₃, Al₂O₃, Na₂O) specify hydrothermal alteration, confirming the orogenic nature of the gold system. Nyakishenyi hosts both structurally controlled orogenic gold deposits and secondary placer accumulations. Integrating structural and geochemical data provides a strong predictive framework for future exploration in the Kibaran Belt and similar Precambrian terrains.