Browsing by Author "Abera, Tadele"

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    Antidiarrheal Activity of Aqueous and 80% Methanol Extracts of the Leaves of Leucas Abyssinica (Lamiaceae) in Mice
    (Addis Abeba University, 2020-11) Abera, Tadele; Abula, Teferra( Professor)
    Leucas abyssinica (Lamiaceae family) is one of the medicinal plants used for the management of diarrhea in Ethiopia but it lacks scientific evidence. Thus, this study was aimed to evaluate the antidiarrheal activities of aqueous and 80% methanol extracts of the leaves of Leucas abyssinica using experimental models in mice. castor oil induced diarrhea, misoprostol induced enteropooling, normal and castor oil induced gastrointestinal transit in mice models were used to evaluate antidiarrheal activity of the plant. Five groups of mice (six animals per group) were used for each model. These groups were negative control group (received distilled water 10 ml/kg), positive control group (administered loperamide 3 mg/kg) and three test groups (treated with graded dose of 100, 200 and 400 mg/kg aqueous and methanol 80% extracts respectively). Pretreatment of mice with stated doses of both extracts of the plant significantly reduced the frequency of wet and total feces, the weight of wet and total feces as well as increased diarrheal free periods compared to negative controls. Both extracts produced significant reduction in both the weight and volume of intestinal contents induced by misoprostol in a dose dependent manner. The percentage of inhibition of gastrointestinal transit induced by castor oil for both extracts were significant (p < 0.001) at all the tested doses in a dose dependent fashion. But none of the tested doses of both extracts significantly reduced normal gastrointestinal transit in mice. Finally, the results from this study suggests that both extracts of the plant have significant antidiarrheal effect on animal models and this finding supports the antidiarrheal traditional use of the plant for management of diarrhea.
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    Frequency Assignment Problem Optimization of GSM Network in the case of Addis Ababa
    (Addis Ababa University, 2014-09) Abera, Tadele; Negash, Yalemzewud
    In GSM systems, radio frequencies are repeatedly used in order to efficiently use assigned frequency bands. To expand the network capacity, one solution is to reuse the limited frequency resources. Currently the 4x3 frequency reuse technologies for GSM network is in common use here in Addis Ababa. For this reuse model “4” indicates the number of Base Transceiver Stations (BTSs) in the reuse clusters, and “3” indicates the number of cells (sectors) under each BTS. As the number of users increases from time to time, the number of cells increases. Thus, the search space which is the possible range where optimum solution is attained increases. Furthermore, attaining optimum frequencies under each cell is challenging task. This thesis presents group frequency assignment method for the frequency assignment problem in Addis Ababa using genetic algorithm technique. Without violating the 4x3 frequency reuse used currently, the optimization was performed in Addis Ababa with 933 DCS (Digital Communication) 1800 MHz bandwidth cells (sectors). With proper optimization five frequencies can be used under each cell with a group of 24 cells and 125 generations or iterations using the algorithm. This assignment enhanced us to use two more frequencies under each cell than ethio telecom assignment which uses Mentum planet as optimization tool. And thus, capacity of the system increased. Key words: Frequency Assignment Problem Optimization; Genetic Algorithm