School of Physical Sciences (Phys-Sciences) Collections

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Now showing 1 - 5 of 227
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    Heavy metal pollution indices in sediments and bio accumulation factor in the root tubers grown in selected wetlands of Lake Victoria Basin
    (Makerere University, 2025) Isooba, Richard
    This study assessed Heavy metal pollution indices in sediments and bioaccumulation in root tubers grown in selected wetlands of Lake Victoria basin. Sediment samples at the surface (at depth < 0.2m) were taken. Plant materials were hand-pulled, and tubers separated, washed and kept at 40C until analysis. Heavy metals were determined using a Perkin Elmer model 1100B AAS, and data were analysed using the analysis of variance (ANOVA) in Excel at a 0.05 significance level (p<0.05). Highest concentrations of Cu and Pb were observed in Murchison Bay sediments ranging from (172.16±2.9) mg/kg Cu and (107.68±2.32) mg/kg Pb in cassava garden to (143.39±2.68) mg/kg Cu and (97.82±2.21) mg/kg Pb in cocoyam gardens. In root tubers, the concentrations were in the order: cassava ˃ sweet potatoes ˃ cocoyam. Nalusojjolo wetland registered the lowest concentrations in both the sediments and tubers. Ni & Cr were relatively low in sediments and root tubers in all the wetlands, except cadmium in Murchison Bay sediments, which exceeded the USEPA permissible limit value of 1.2mg/kg. Murchison Bay recorded the highest mean concentration of metal with Cu > Cr >Pb > Ni > Cd, and Nalusojjolo the least. The Cf and PLI values for the metals observed in this study displayed, Nalusojjolo and Kyetinda wetlands were uncontaminated for all metals except Cd, with moderate contamination in Kyetinda wetland. Ni and Cr in both Murchison Bay and Namanve registered Cf to low contamination. Murchison Bay and Namanve wetland had considerable Cf values of 4.012 and 5.103 for Cu, Pb and 3.075 and 4.900 for Pb, Cd, respectively. Nalusojjolo and Kyetinda PLI < 1, while the other two wetlands had PLI ˃ 1. The I-geo rating for Cu, Pb, Ni and Cr were < 0 for Nalusojjolo and Kyetinda wetlands, except Cd in Kyetinda. Therefore, Cu, Pb, Ni and Cr levels in sediments were not from anthropogenic activity but may be from parent material that formed the soil. The Igeo ˃ 0 for Murchison Bay and Namanve for Cu, Pb and Cd implied that most of the metal pollution originates from anthropogenic activities. The BAF values for all plants were < 0 despite of high concentration of metal in roots, suggesting that tubers can absorb but not bioaccumulate the metal.
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    Geological and geomorphological factors influencing mass wasting susceptibility in the Nyabage Watershed, Kabezi Commune, Wetern Burundi
    (Makerere University, 2025) Kwizera, Adronis
    Landslides are among the most destructive natural hazards in Burundi, particularly within the Nyabage watershed of Kabezi Commune, where they pose a serious threat to infrastructure, human lives, and land use sustainability. This study assessed the geological and geomorphological factors influencing mass wasting susceptibility in this region by integrating field investigations, laboratory testing, petrographic analysis, and spatial modeling. Twelve rock samples and over forty soil samples were collected and analyzed to evaluate key physical and mechanical properties, including grain size distribution, Atterberg limits, porosity, permeability, shear strength, and uniaxial compressive strength. Petrographic analysis of thin sections revealed that the watershed is underlain by biotite- and muscovite-rich lithologies, including granite gneiss, granite, and micaceous sandstone, which are structurally weak due to schistosity, foliation, and pervasive microfracturing. These lithologies significantly reduce shear strength and promote water infiltration. ArcGIS 10.8 spatial analysis combined with kriging interpolation reveals that landslides in the Nyabage watershed mainly occur on steep, concave slopes (20°–40°), eastern aspects, and areas with high moisture content. These zones feature fine-grained, cohesive soils with moderate to high plasticity (PI 8–19%), a liquid limit of 39.3%, a plastic limit of 27.1%, high porosity (32%), low permeability (8.8 × 10⁻⁶ m/s), and low shear strength (friction angle 18.64°; cohesion 44.3 kPa). When paired with structurally weak rocks and intensified land use or deforestation, these geotechnical and geomorphic factors primarily control landslide occurrences in the watershed. This study demonstrates that the susceptibility to mass wasting in the Nyabage watershed arises from a combination of lithological weakness, geotechnical vulnerability, slope configuration, and anthropogenic pressure. The integrated methodological approach offers a scientifically robust framework for hazard mapping and risk assessment. These findings contribute to regional disaster risk reduction strategies and support informed land-use planning and infrastructure development in geologically sensitive areas.
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    Geological and geomorphological factors influencing mass wasting susceptibility in the Nyabage Watershed, Kabezi Commune, Western Burundi
    (Makerere University, 2025) Kwizera, Adronis
    Landslides are among the most destructive natural hazards in Burundi, particularly within the Nyabage watershed of Kabezi Commune, where they pose a serious threat to infrastructure, human lives, and land use sustainability. This study assessed the geological and geomorphological factors influencing mass wasting susceptibility in this region by integrating field investigations, laboratory testing, petrographic analysis, and spatial modeling. Twelve rock samples and over forty soil samples were collected and analyzed to evaluate key physical and mechanical properties, including grain size distribution, Atterberg limits, porosity, permeability, shear strength, and uniaxial compressive strength. Petrographic analysis of thin sections revealed that the watershed is underlain by biotite- and muscovite-rich lithologies, including granite gneiss, granite, and micaceous sandstone, which are structurally weak due to schistosity, foliation, and pervasive microfracturing. These lithologies significantly reduce shear strength and promote water infiltration. ArcGIS 10.8 spatial analysis combined with kriging interpolation reveals that landslides in the Nyabage watershed mainly occur on steep, concave slopes (20°–40°), eastern aspects, and areas with high moisture content. These zones feature fine-grained, cohesive soils with moderate to high plasticity (PI 8–19%), a liquid limit of 39.3%, a plastic limit of 27.1%, high porosity (32%), low permeability (8.8 × 10⁻⁶ m/s), and low shear strength (friction angle 18.64°; cohesion 44.3 kPa). When paired with structurally weak rocks and intensified land use or deforestation, these geotechnical and geomorphic factors primarily control landslide occurrences in the watershed. This study demonstrates that the susceptibility to mass wasting in the Nyabage watershed arises from a combination of lithological weakness, geotechnical vulnerability, slope configuration, and anthropogenic pressure. The integrated methodological approach offers a scientifically robust framework for hazard mapping and risk assessment. These findings contribute to regional disaster risk reduction strategies and support informed land-use planning and infrastructure development in geologically sensitive areas.
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    A hybrid stress testing mathematical model for evaluating financial stability in selected commercial banks in Uganda
    (Makerere University, 2025) Bwesigye, Emmanuel
    This study is on the multidimensional risks a ecting commercial banks in Uganda through the development of a hybrid stress testing model that integrates market, credit, liquid- ity, systemic, and climate-related risks. The study enhances nancial system resilience by capturing both idiosyncratic and systemic vulnerabilities through simulation-based methodologies tailored to the Ugandan context. The study focuses on eleven commercial banks in Uganda that were selected based on pro tability as at the end of 2023. The study approach combines agent-based modeling, Monte Carlo simulations, and scenario analysis to evaluate the impact of extreme but plausible macro- nancial shocks. The Climate Extended Risk Model (CERM) was im- plemented to project climate-induced GDP losses using historical trends and stochastic climate parameters. Systemic risk was modeled through interbank exposure networks and covariance-based metrics to simulate contagion and failure cascades. Market and credit risks were assessed using Value-at-Risk (VaR), CoVaR and ∆CoVaR, applied to Uganda-speci c macroeconomic indicators. Results show that severe physical climate risk scenarios could cause cumulative GDP losses of approximately UGX 1.87 trillion (≈ USD 492 million) over 25 years. Credit losses tied to agricultural lending are projected to reach UGX 21.43 billion (≈ USD 5.6 million). Simulated contagion revealed an average of 3.54 bank failures per shock, corresponding to expected losses of UGX 565.70 billion (≈ USD 150 million). Liquidity and capital bu ers of less pro table commercial banks were found to be more vulnerable to cascading defaults; with a total liquidity loss of UGX 138.55 billion (≈ USD 36.46 million). Total CoVaR estimates indicate potential losses of UGX 115.15 billion (≈ USD 31 million) for credit risk and UGX 91.82 billion (≈ USD 25 million) for market risk, primarily driven by exchange rate volatility (exchange rate is assumed to be UGX 3800 per USD). The ndings underscore the urgent need for policymakers and regulators to strengthen macroprudential policies, enhance climate- nancial risk disclosure, and promote sectoral diversi cation in lending portfolios. It is recommended that the Bank of Uganda adopt hybrid stress testing models in supervisory practices and expand data collection for gran- ular sectoral exposures. Targeted capital and liquidity requirements for vulnerable com- mercial banks, coupled with coordinated climate adaptation policies, will be critical for safeguarding nancial stability in Uganda
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    On the construction of cousin complexes
    (Makerere University, 2025) Wepukhulu, Nick
    This research aims to construct Cousin complexes that exhibit geometric and algebraic properties. The geometric construction begins with a topological space X endowed with a decreasing filtration of closed subsets Zₙ ⊆ ⋯ ⊆ Z^2⊆ Z^1⊆ X , and employs sheaves and their sections with support in these subsets. By applying the global section functor Γ(X,-), its variants Γ_Z (X,-),Γ_(z_1/z_2 ) (X,-) and their derived functors Hⁱ(X,-),Hⁱ_z (X,-) and Hⁱ_(z_1/z_2 ) (X,-), long exact sequences in cohomology are obtained, from which the geometric version of the Cousin complex is constructed. The algebraic analogue is constructed using an A-module over a commutative ring A. Beginning with an A-module M and defining the initial morphisms d^(-2): M^(-2)→ M^(-1) with M^(-2)= 0 and M^(-1)= M, the construction proceeds inductively to produce a Cousin complex 0 → M →ᵈ^(-1) M^0→ᵈ^0 M^1→ᵈ^1⋯ .