Faculty of Science (FSC)

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Now showing 1 - 5 of 39
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    Characterizing absolutely irreducible integer-valued polynomials over discrete valuation domains
    (Journal of Algebra 633 (2023) 696–72, 2023-08-12) Hiebler, Moritz; Nakato, Sarah; Roswitha,Rissner
    Rings of integer-valued polynomials are known to be atomic, non-factorial rings furnishing examples for both irreducible elements for which all powers factor uniquely (absolutely irreducibles) and irreducible elements where some power has a factorization different from the trivial one. In this paper, we study irreducible polynomials F ∈ Int(R) where R is a discrete valuation domain with finite residue field and show that it is possible to explicitly determine a number S ∈ N that reduces the absolute irreducibility of F to the unique factorization of F S . To this end, we establish a connection between the factors of powers of F and the kernel of a certain linear map that we associate to F . This connection yields a characterization of absolute irreducibility in terms of this so-called fixed divisor kernel. Given a non-trivial element v of this kernel, we explicitly construct non-trivial factorizations of F k , provided that k ≥ L, where L depends on F as well as the choice of v. We further show that this bound cannot be improved in general. Additionally, we provide other (larger) lower bounds for k, one of which only depends on the valuation of the denominator of F and the size of the residue class field of R.
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    Conservation of forest biomass and forest–dependent wildlife population: Uncertainty quantification of the model parameters
    (Heliyon, 2023-07-06) Ibrahim, M. Fanuel; Silas, Mirau; Damian, Kajunguri; Francis, Moyo
    The ecosystem is confronted with numerous challenges as a consequence of the escalating human population and its corresponding activities. Among these challenges lies the degradation of forest biomass, which directly contributes to a reduction in forested areas and poses a significant threat to the survival of wildlife species through the intensification of intraspecific competition. In this paper, a non–linear mathematical model to study the conservation of forest and wildlife species that are reliant on forest ecosystem within the framework of human population dynamics and its related activities is developed and analysed. The study assessed the impacts of economic measures in the form of incentives on reducing population pressure on forest resources as well as the potential benefits of technological efforts to accelerate the rate of reforestation. Qualitative and quantitative analyses reveals that economic and technological factors have the potential to contribute to resource conservation efforts. However, these efforts can only be used to a limited extent, and contrary to that, the system will be destabilised. Sensitivity analysis identified the parameters pertaining to human population, human activities, economic measures, and technological efforts as the most influential factors in the model.
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    Modeling Radionuclide Transfer from Pasture to Milk in Kisoro, South- Western Uganda
    (East African Journal of Science, Technology and Innovation,, 2023-06-30) Habakwiha V,; Oruru B,; Tumps Ireeta W
    Determination of radionuclide transfer from animal feeds to animal products and ingestion transfer rates is important in assessing internal radiation risk to humans who consume the animal products. Seventy-nine (79) pasture samples and milk samples were collected from cattle farms in seven sub- counties. Activity concentrations of radionuclides in the samples were determined using gamma spectroscopy. Transfer ratios of radionuclides to from pasture to milk were calculated. Ingestion transfer rates of radionuclide from pasture to cow were also determined. Radionuclide accumulation to the body of the cow was modeled. Contributions to radiological effects due to accumulation of radionuclides in the body were estimated. Transfer ratios of uranium and thorium from pasture to milk varied from 0.07 to 0.17, and 0.05 to 0.17, respectively. The ingestion transfer rates of uranium varied from 3.1 10-6 to 7.6 10-6 y l-1 while for thorium, the ingestion transfer rates varied from 2.2 10-6 to 7.5 10-6 y l-1. The contribution to radium equivalent (Bq l-1), annual effective dose equivalent (mSv y l-1), and excess lifetime cancer Risk due to the radionuclide transfer were 0.074, 0.002, and 0.0061 10-3, respectively. Comparing with the safe values of annual effective dose equivalent in foodstuffs of 0.14 mSv y l-1 which translates to excess cancer risk of 0.42 10-3, these contributions to radiological effects only account for about 1.5% of the total safe value of excess lifetime cancer risk, therefore, radionuclide transfer from pasture to milk causes a minimal radiation hazard to the milk consumers in Kisoro District.
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    Citrus Fruit Farmers’ Adaptation Capacities to Climate Variability in Ngora District, Eastern Uganda.
    (Kabale University, 2022) Achuu, Simon Peter; Nachuha, Sarah; Nakizito, Joweria; Musoke, Semakula Henry; Opedes, Hosea Enos
    Over the past three decades the government of Uganda prioritized fruits growing in Teso sub-region as a means to promote socioeconomic development. However, climate variability threatens the realization of this initiative and yet inadequate research has been done to address this gap. This study assessed citrus fruit farmers’ adaptation capacities to climate variability in Ngora district, eastern Uganda. Longitudinal and cross-sectional research designs were adopted in which 135 randomly selected farmers were interviewed. Findings indicated that 82% of the respondents attested that rainfall amounts and temperature patterns had changed with the highest rainfall of 1686 mm received in 1991, and the lowest amount of 785mm received in 2009. Average annual temperatures in the same period varied between 23.8ºC and 25.7ºC. These variations contributed to a drop in orange fruit yields from 90% in 2015 to below 54% in 2016. Overall, 94.8% of citrus farmers were aware of the term climate variability and they associated it to variation in rainfall amounts and distribution, rise in surface temperature and occurrence of droughts; 73.3% of the farmers had positive attitude towards climate variability adaptation especially in instances where it directly affected their livelihoods. Only 21% of the farmers did something to adapt to climate variability through irrigating young orange trees. Conclusively, citrus growing provided an option to poverty eradication, however climate variability threatens farmer’s efforts. In a short-run farmers may be encouraged to work in groups. Overall capital investment on irrigation technology by government and or other stakeholders will offer lasting solutions. Keywords: Citrus Fruits - Climatic Factors, Climatic Changes, Agriculture - Environmental Aspects , Ngora District, Uganda.
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    Antiplasmodial Compounds from Millettia Dura.
    (Kabale University, 2022) Buyinza, Daniel; Derese, Solomon; Ndakala, Albert
    Malaria still poses a big challenge to the health care of many tropical countries. The plasmodium resistance to the conventional drugs is the major hitch in its treatment. Higher plants have produced single line antimalarials and given important lead molecules. On this basis, flavonoids isolated from millettia dura by chromatographic techniques were screened againest W2 and D6 strains of plasmoduim falcipalum. Both, the crude and pure compounds tested showed mild activities against the test organisms. The crude extract of the stem bark had the highest respective activity of 63.7±8.6 and 46.1±4.5 μg/ml against W2 and D6. Of the pure compounds, milletosin was active towards both W2 and D6 with a respective IC50s of 87.9±8.9 and 66.70±30.3 μg/ml. Synergistic effect might have contributed to the relative high activity of the crude than the pure compounds. Basing on the structure activity relationship of the tested compounds, suitable structural modification could be ideal to enhance the antiplasmodial activity. Keywords: Antiplasmodial, Compounds, Millettia Dura.