Addis Ababa University
  • Addis Ababa, Addis Ababa, Ethiopia
Recent publications
Honey is a sweet natural product synthesized from nectars of flowers by different types of honey bees. It has been used as medicine in different cultures. The aim of this study was to investigate the antimicrobial activities of honey samples from different sources against selected clinical and standard microorganisms. Antimicrobial activities of the honey samples against selected standard and clinical microorganisms were done using agar disc and agar well diffusion methods. The highest diameter of inhibition zone against clinical and standard strains was recorded for Meliponula beccarii honey (MBH) (16 ± 3 mm) followed by Apis mellifera fresh honey (AMFH) (15 ± 2 mm) and Apis mellifera market honey (AMMH) (11 ± 3 mm) by well diffusion method. The mean inhibition zone recorded by the disc diffusion method were generally lower than that of the well diffusion method. However, none of the honey samples inhibited Candida albicans. The mean Minimum Inhibitory Concentration (%) and Minimum Bactericidal Concentration (%) against all the tested bacteria were 9.9 and 53.6 by MBH, 11.0 and 56.2 by AMFH, and 15.4 and 64.3 by AMMH, respectively. The fresh honey samples directly collected from the hives and honey samples from stingless bees showed higher antimicrobial effects against the tested pathogenic bacteria. This implies that honey could be used as an alternative therapy against diseases caused by the bacterial pathogens.
Chrome tanned leather accounts for 90% of leather in the world. However, chromium is a global environmental disaster and puts the health of millions of leather workers and ordinary citizens at risk. The use of natural materials that is eco-friendly on leather as vegetable tanning is therefore, a matter of significant importance. Thus, the current study focused to investigate the potential effectiveness of the extracted tannin from Sodom apple (Solanum Incanum) fruit as vegetable tanning agent on goatskins. It was extracted with distilled water, methanol, petroleum ether and ethanol by using Soxhlet extraction method. Although the amount of material extracted was significant in all extracting solvents, water was a more efficient solvent (extraction yield of 16.71%) than the others. The qualitative analysis and structural characterization of the extracts were done using thin-layer chromatography (TLC), Ultraviolet (UV) spectrometer and Fourier Transform Infrared (FT-IR) spectrometer which confirmed the presence of condensed tannins in the extract. The Scanning Electron Microscope (SEM) was carried out to study the effect of the tannin system on the structural and morphological characteristics of the tanned leathers. Similarly, the organoleptic and strength properties of the tanned leathers were evaluated in comparison with the control ones. Finally, the pollution load of tanning liquors in Sodom apple tanning was significantly reduced as compared to the control (mimosa). Hence, from the current study, it is possible to conclude that Sodom apple fruit extract is a cleaner alternative and promising pathway for goatskin tanning.
Nowadays, video streaming has become one of the most dominant services due to increasing interest in watching online television programs and video-on-demand activities. Providing this service requires high quality, high speed and high-capacity network infrastructures. In this work, we propose a data-driven-based fuzzy logic inference algorithm for quality of experience (QoE) modeling of video streaming services in Addis Ababa City LTE network. The proposed fuzzy logic inference system model is used to measure the user perception from the key quality of indicator (KQI) parameters. The model is essential to replace conventional subjective measurement techniques that are costly and inefficient. In addition, the proposed fuzzy logic inference system model is helpful for business decision making, network planning and optimization activities. To analyze the performance of the proposed model, we consider main KQI parameters such as video streaming start success rate, video streaming start delay, video streaming play disconnection rate, video streaming stall frequency and video streaming stalled time rate. We perform numerical simulation to analyze the proposed model and to validate the impacts of main KQI parameters on the quality of experience in LTE video streaming services. The simulation results show that video streaming stall frequency and video streaming start delay rate play a major impact on user perception by 33% and 25%, respectively. Besides, validation of the results shows that the proposed fuzzy logic inference system model is accurate, consistent and linear compared to currently existing models. © 2022 The Author(s). This open access article is distributed under a Creative Commons Attribution (CC-BY) 4.0 license.
Form several countries trend bamboo has been used as a scaffolding material in building projects. Nonetheless, Ethiopia is known for the high population of bamboo vegetation such utilization of the material remained untapped. The purpose of this paper is to identify factors that influence bamboo’s structural suitability as a temporary material and to create a conceptual map for using it as an alternative structural material. Following the identification of important applications influencing parameters via literature analysis, both qualitative and quantitative approaches were used to identify significant factors. The paper also used a series of protocols; at first, several documents were selected based on criteria to provide an overview of bamboo-based construction systems. Following that, four major categories for SWOT analysis were chosen to examine the Ethiopian construction industry’s stance on the use of bamboo as a scaffolding material. Finally, a scoring model was employed as a quantitative analysis protocol to calculate the weight of factors (safety, procedure and implementation, time, and cost) through expert opinions. The investigation revealed that the use of bamboo has a cost and time savings advantage, while an increase in trash at acute and intermittent areas was one of the challenges. Furthermore, one of the challenges in creating bamboo formwork is a lack of complementary joinery techniques. Besides that, it is expected that the bamboo content will fall short of technical requirements. On the Brightside, every single respondent stated unequivocally that bamboo-made formwork meets a low-cost requirement.
Abstract This study aimed at examining journalists’ organizational trust by focusing on the relationships to the predictor variables of organizational commitment, job satisfaction and socio-economic exchanges at Amhara Media Corporation (AMC). Data were collected from self-administered report scales of 250 full-time employed journalists in the head office and across six branches of AMC in Ethiopia. The result of multiple regression analysis showed there were statistically significant associations of organizational trust with commitment, social exchange and job satisfaction positively and with economic exchange negatively. The higher levels of organizational commitment and social exchange journalists experience in AMC are associated with higher levels of organizational trust. Journalists’ job satisfaction had a minimum impact on their organizational trust. The economic exchange journalists had in AMC did not determine their level of trust. Further, the result of parallel mediation analysis conducted using the Hayes PROCESS macro model showed organizational commitment and organizational trust were fully mediated by social exchange and job satisfaction. Journalists with high organizational commitment were likely to have higher levels of social exchange and job satisfaction indicating a culture of high levels of social exchange and job satisfaction are more likely to lead to trust in the media organization. Keywords: Amhara Media Corporation; journalists; organizational trust; organizational commitment; parallel mediation analysis; socio-economic exchanges
Foreign aid is one source of physical capital accumulation in Ethiopia. It is also a main media of government revenue in meeting increasing trends of government expenditure. To investigate the impact of foreign aid flow on economic growth, various empirical studies were conducted, but they came up with mixed result. This leads to raise question of why impact of aid on economic growth in Ethiopia continues to be paradoxical in its findings. To assess the effectiveness of foreign aid in Ethiopia; this study sets predictability of foreign aid and economic growth in Ethiopia as a general objective. Specifically, the study sought to examine the contribution of foreign aid and the macroeconomic policy environment to economic growth in the country. In order to meet the aforementioned objective, the study employed an autoregressive distributed lag (ARDL) approach over the period 1985-2019. The empirical finding shows that foreign aid has a positive role in economic growth in the long run but its short run effect is found to be insignificant. Again, this finding also reveals that both in the short run and long run the predictability of foreign aid has a positive effect both on economic growth. Macroeconomic policy index also has a positive effect in the long run, but its short run effect become negative. Based on the listed empirical finding, the study came up with policy recommendation; the government should allocate the external assistance on the successful development projects rather than simply on consumption. Furthermore, for the persistent and predictable flow of foreign aid overtime, joint mechanism of transparency has to be developed between Ethiopian government and donor communities. Keywords: Foreign Aid; Ethiopia; Economic Growth; Macroeconomic Policy; ARDL
Background The need for understanding spatial distribution of forest aboveground carbon density (ACD) has increased to improve management practices of forest ecosystems. This study examined spatial distribution of the ACD in the Harana Forest. A grid sampling technique was employed and three nested circular plots were established at each point where grids intersected. Forest-related data were collected from 1122 plots while the ACD of each plot was estimated using the established allometric equation. Environmental variables in raster format were downloaded from open sources and resampled into a spatial resolution of 30 m. Descriptive statistics were computed to summarize the ACD. A Random Forest classification model in the R-software package was used to select strong predictors, and to predict the spatial distribution of ACD. Results The mean ACD was estimated at 131.505 ton per ha in this study area. The spatial prediction showed that the high class of the ACD was confined to eastern and southwest parts of the Harana Forest. The Moran’s statistics depicted similar observations showing the higher clustering of ACD in the eastern and southern parts of the study area. The higher ACD clustering was linked with the higher species richness, species diversity, tree density, tree height, clay content, and SOC. Conversely, the lower ACD clustering in the Harana Forest was associated with higher soil cation exchange capacity, silt content, and precipitation. Conclusions The spatial distribution of ACD in this study area was mainly influenced by attributes of the forest stand and edaphic factors in comparison to topographic and climatic factors. Our findings could provide basis for better management and conservation of aboveground carbon storage in the Harana Forest, which may contribute to Ethiopia’s strategy of reducing carbon emission.
Background This study was carried out in Gerba Dima Forest, South-Western Ethiopia, to determine the floristic composition, species diversity and community types along environmental gradients. Identifying and interpreting the structure of species assemblages is the main goal of plant community ecology. Investigation of forest community composition and structure is very useful in understanding the status of tree population, regeneration, and diversity for conservation purposes. Method Ninety sample plots having a size of 25 × 25 m (625 m ² ) were laid by employing stratified random sampling. Nested plots were used to sample plants of different sizes and different environmental variables. All woody plant species with Diameter at breast height (DBH) ≥ 2.5 cm and height ≥ 1.5 m were recorded in 25 m × 25 m plots. Hierarchical (agglomerative) cluster analysis was performed using the free statistical software R version 3.6.1 using package cluster to classify the vegetation into plant community types. Redundancy Analysis (RDA) ordination was used in describing the pattern of plant communities along an environmental gradient. Result One hundred and eighty plant species belonging to 145 genera, 69 families and comprising of 15 endemic species were recorded. Of these, 52 species (28.9%) were trees, 6 species (3.33%) were Trees/shrubs, 31 species (17.22%) were shrubs, 76 species (42.22%) were herbs, and 15 species (8.33%) were Lianas. Rubiaceae , Acanthaceae and Asteraceae were the richest family each represented by 11 genera and 11 species (6.11%), 9 genera and 11 species (6.11%), 6 genera and 11 species (6.11%), respectively of total floristic composition. Cluster analysis resulted in five different plant communities and this result was supported by the ordination result. RDA result showed altitude was the main environmental variable in determining the plant communities. The ANOVA test indicated that the five community types differ significantly from each other with regard to Electrical Conductivity and Potassium. Conclusions Description of floristic diversity of species in Gerba Dima forest revealed the presence of high species diversity and richness. The presence of endemic plant species in the study forest shows the potential of the area for biodiversity conservation.
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3,736 members
Ermias Lulekal
  • Department of Plant Biology and Biodiversity Management
Wamisho, B.L.
  • Department of Orthopedics
Negussie Deyessa
  • Department of Internal Medicine
Bekele Megersa
  • College of Veterinary Medicine and Agriculture
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