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Nighttime ionospheric irregularity during intense geomagnetic storm events over the Europe-African longitudinal sector

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Heliyon 2024年第19期10卷 e38138页

作者： Kassa, Yibekal Tebabal, Ambelu Damtie, Baylie College of Science Department of Physics Washera Geospace and Radar Science Research Laboratory (WaGRL) Bahir Dar University Ethiopia College of Natural and Computational Science Department of Physics Debre Markos University Ethiopia Institute of Geophysics Space Science and Astronomy Addis Ababa University Ethiopia

Radio communication and navigation systems can be severely impacted by irregularities in the ionosphere. There is still much to learn about how geomagnetic storms affect the occurrence of these irregularities. Ionosphere studies in different regions, particularly the equatorial and low-latitudes, are necessary to enhance the forecasting of this phenomenon. This study investigates the effect of intense geomagnetic storm events of August 27, October 7 and December 22, 2015, on nighttime ionospheric irregularities. Data collected from the receivers of the Global Navigation Satellite Systems (GNSS) in specific longitudinal sector of 15^∘W – 0^∘, 0^∘ – 15^∘E, 15^∘E – 30^∘E and 30^∘E – 45^∘E, as well as from the Swarm constellations in the longitude range of 30^∘W – 70^∘E and the latitude range of 50^∘S – 50^∘N, have been used. The rate of change of the total electron content (TEC) index (ROTI) and the rate of change of the electron density index (RODI) were analyzed. In the main phases of the storms, at equatorial and low-latitude regions we observed ionospheric irregularities in the African longitudinal sectors of 15^∘W – 0^∘, 0^∘ – 15^∘E and 30^∘E – 45^∘E in the three storm events. The observed ionospheric irregularities were more pronounced in the western than eastern regions. These irregularities were possibly driven by the Prompt Penetration Electric Fields (PPEFs) that point east to west during nighttime. Ionospheric irregularities were inhibited in the selected storm periods over the middle latitudes in the African sector. In the longitudinal sector of 15^∘E – 30^∘E, we obtained inhibition of irregularity in the study periods. In the case of the top-side ionosphere, we observed enhanced and depleted electron density during the storm in the low latitude and equatorial

关键词： Geomagnetic storm Irregularity Longitudinal sectors RODI ROTI

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Ignoring the Impact of Fermentation Could Result in Substantial Misestimation of Folate and Cobalamin Adequacy: A Simulation Study on Injera Consumption in the Ethiopian Context

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Current Developments in Nutrition 2025年第4期9卷 104581-104581页

作者： Verger, Eric O Fortin, Sonia Tamene, Aynadis Ashagrie, Henok Mouquet-Rivier, Claire Humblot, Christèle MoISA Univ Montpellier CIRAD CIHEAM-IAMM INRAE IRD L'Institut Agro Montpellier France Qualisud Univ Montpellier IRD Institut Agro CIRAD Avignon Université Univ de La Réunion Montpellier France Center for Food Science and Nutrition College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia

B-vitamin content of plant-based foods can be deeply modified by fermentation, particularly the active cobalamin form, which is often considered to be zero in food composition databases. We simulated the consequences of including or excluding the impact of fermentation in estimating folate and cobalamin adequacy using secondary data obtained from a survey of 323 women in Ethiopia plus the vitamin content of injera (fermented flat bread) reported in the literature. As folate content can change during fermentation, the prevalence of inadequacy in scenarios that include the effect of fermentation was higher (90%) or lower (67%) than in the original data. Our simulation based on data obtained using cobalamin-producing microorganisms lowered the prevalence of inadequacy to 54%. Ignoring the impact of fermentation may result in substantial misestimation of folate and cobalamin adequacy in Ethiopia, and it should be evaluated in other contexts in which fermented foods are consumed as staple foods. © 2025 The Author(s)

关键词： fermented food nutrient adequacy resource-poor settings vitamin B12 vitamin B9

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The sustainability of reforesting landscapes with exotic species: a case study of eucalypts in Ethiopia

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Sustainable Earth 2021年第1期4卷 1-11页

作者： Zerga, Belay Warkineh, Bikila Teketay, Demel Woldetsadik, Muluneh Center for Environmental Science College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia Department of Plant Biology and Biodiversity Management College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia Department of Natural Resources Management College of Agriculture and Natural Resource Wolkite University Gubrei Ethiopia Department of Range and Forest Resources Faculty of Natural Resources Botswana University of Agriculture and Natural Resources Sebele Botswana Department of Geography and Environmental Studies College of Social Sciences Addis Ababa University Addis Ababa Ethiopia

Eucalypt reforestation has been a common feature of many countries, especially in the developing countries, such as Ethiopia. Farmers in Ethiopia plant large numbers of eucalypts on small areas of land and manage them to yield a variety of products, including leaves and small branches for fuelwood, and poles and posts for house building and other farm uses. Many people in Ethiopia are dependent on eucalypts as a source of fuel and house building material. The use of trees, especially eucalypts, as a living bank account, to be harvested when there is a need for cash, is widespread. This being the reality, the arguments for and against planting eucalypts in Ethiopia has been mounting from time to time, especially associated with water use, soil fertility, soil erosion, allelopathic effects, understory vegetation and plant diversity as well as wild animals. The paradox of reforestation using eucalypts results, mostly, from inappropriate species-site matching and poor management rather than the inherent biological characteristics of the species. Therefore, the debate on eucalypts under the pretext of concern for indigenous species and natural forests should shift to how both plantations established using eucalypts and indigenous species as well as natural forests can help in the enhancement of the socio-economic development and environmental conservation of countries, such as Ethiopia. Despite the claimed negative impacts of eucalypts, farmers in Ethiopia have utilized their traditional knowledge and experience in establishing and managing eucalypt stands. In addition, the available reports in Ethiopia are in favour of planting eucalypts since the authors acknowledge that: (i) the negative impacts can be minimized provided that the choice of species and site as well as the management of the stands are appropriate, (ii) the benefit derived can offset the losses that can occur from such plantations, (iii) no other species seems to replace them to bridge the ever-widening

关键词： Allelopathic impact hydrology plant diversity soil fertility and erosion wild animals policy implications

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The Effect of MS strength, pH and Sucrose Concentrations on In vitro Propagation of Okra (A belmoschus esculentus L.) from Shoot Tip Explants .

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Research Square 2021年

作者： Woldeyes, Girma Gebrehiwot Senbeta, Tileye Feyissa Adugna, Alelegne Yeshamebel Abegaz, Agegnehu Wasse Department of Biology Meskerem Secondary School Addis Ababa Ethiopia Institute of Biotechnology Addis Ababa University Addis Ababa Ethiopia Department of Biology Faculty of Natural and Computational Science Kotebe Metropolitan University Addis Ababa Ethiopia Department of Biology Faculty of Natural and computational science Wolayta Sodo University Ethiopia

Background Okra (Abelmoschus esculentus) is belongs to the family Malvaceae and genus Hibiscus. Conventional propagation of okra in a large scale is limited due to bacterial, fungal, viral disease and seed dormancy. Hence, micropropagation offers great potential to increasing the commercial availability of okra. This study aimed to investigate the effect of MS strength, sucrose concentration, and pH on the in vitro propagation of A. esculentus from shoot tips. Results Okra seeds were sterilized with 70% alcohol, 30% (v/v) Berekina and 0.13% HgCl2 (w/v) for 5, 40 and 10 minutes respectively. The shoots were excised from in vitro germinated seedlings and transferred to full strength MS liquid medium containing 1mg/L BAP. The in vitro initiated shoot tips were transferred to different MS strength (1, ½,, ¼) medium, sucrose concentration (30 g/L, 20 g/L, 15 g/L, 10 g/L) and pH level (pH 6.6, 6.2, 5.8, 5.4, 5.0) that contained 1.5 mg/L BAP and 200 mg/L activated charcoal. For rooting, different MS strength (full, ½,, ¼), sucrose (30 g/L, 20 g/L, 15 g/L and 10 g/L) and pH (6.6, 6.2, 5.8, 5.4, 5.0) that contained 1mg/L IBA with 200 mg/L activated charcoal were used. Full strength MS medium containing 30 g/L sucrose at pH 5.8 produced the highest mean shoot number (7.93), mean leaf number (14.37) and mean length (6.4 cm) per explant. Similarly, at pH 6.2 and 6.6 maximum shoot mean number (6.53, 5.80), leaf number (12.77, 10.43) and shoot length (6.32, 5.82 cm) were produced respectively. Maximum mean root number (15.73) and root length (6.05 cm) were recorded at ½ MS strength. At pH 5.8, 6.2 and 6.6 maximum mean root number (1.77, 1.47, 1.80) and root length (1.38, 1.25, 1.39 cm) were obtained. After acclimatization, 86% of plants survived in greenhouse. Conclusion Decreasing the MS strength, sucrose concentration and pH level had an inhibiting effect on both shoot multiplication and root formation of okra. Besides increasing pH value showed inhibiting effect on shoot multi

关键词： Sugar (sucrose)

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Numerical Calculations for a Boundary Layer Flow past a Moving Vertical Porous Plate with Suction/Injection and Thermal Radiation

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Applied Mathematics 2020年第3期11卷 172-183页

作者： Okey Oseloka Onyejekwe Yohannes Demiss Belete Nahom Alemseged Worku Computational Mechanics and Dynamics Systems Group Computational Science Program Addis Ababa University Arat Kilo Campus Addis Ababa Ethiopia

The work presented herein investigates the velocity, heat transfer, Nusselt number and skin friction profiles involved in boundary layer flow past a moving vertical porous plate. Similarity transformations are employed to convert the governing nonlinear unsteady momentum and energy equations from their partial differential equation forms to boundary value ordinary differential equations. The resulting equations are then solved numerically by the Runge-Kutta fourth order method with the help of a shooting technique. Several features of the flow and heat transfer characteristics for different values of problem parameters are analyzed and discussed. These include the effects of the radiation parameter (R), suction and injection parameter (c), Grashof (Gr) and Prandtl (Pr) numbers on the flow and heat profiles. Numerical results show the impact of blowing and sucking as well as radation on boundary layer flows of this type. Both the skin frictions as well as the heat transfer rate are also significantly related to the radiation parameter. For all these cases;the numerical results are found to be in agreement with the physics of the problem.

关键词： Momentum and Energy Grashof Number Prandtl Number Similarity Transformation Radiation Parameter Suction Blowing Radiation Po-rous Plate

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Environmental Radioactivity evaluation and its health-related effects using gamma spectrometry in Delanta-Dawunt, Wollo District, Ethiopia

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Research Square 2021年

作者： Legasu, Mekuanint Lemlem Chaubey, Ashok K. Addis Ababa University School of Computational and Natural Science Department of Physics Nuclear Physics Stream Arat Kilo Addis Ababa Ethiopia

Background & Methodology : The specific activity concentration of naturally occurring radionuclides 226Ra, 232Th, 40K and their health related effects were determined in different environmental samples(gemstones) collected from Delanta-Dawunt. Which is one of the mining place in Ethiopia to extract mainly opals (gemstones). Sample collection and the gamma spectroscopic analysis followed the recommended international procedures for such type of research. Gamma-ray spectrometry was applied using HPGe gamma-ray detector and PC-based MCA. The Purpose of this research: to determine the activity concentrations of the radionuclides U/Th series and K of gemstones(opals), to determine life time cancer risk of radionuclide in the environment, to assess the hazard and risk to the public associated with these dose values, to conduct the geochemical studies by quantifying the levels of trace gemstones as well as the physical parameters in soil samples within and around it, and To determine the radiation doses from these activity concentrations and compare with international recommended dose limits. Results: The results of the activity concentration on our research work showed significant variations from 11.97 ± 2.46 to 62.44 ± 14.99 Bq kg-1 for 226Ra, 25.69 ± 3.69 to 137.84 ± 13.23 Bq kg-1 for 232Th and 184.84 ± 3.59 to 969.56 ±18.16 Bq kg-1 for 40K. The mean radioactivity concentration of 226Ra, 232Th, and 40K was found to be around 29.84 ± 6.53, 68.44 ± 18.94, 390.87 ± 6.09 Bk kg-1 respectively. Conculsion: The mean values of Radium equivalent activity (Raeq), absorbed dose, annual effective dose equivalent, external and internal radiation hazard (Hex and Hin) index,and activity utilization index is 151.68±19.46 Bq kg-1, 72.19 ± 8.48 nGy h-1, 0.07 ± 0.01mSv y-1,0.43, 0.51, 0.57 ± 0.08 and 0.29 ± 0.03 respectively. The specific activity of 232Th is higher than the world mean value and 40K is the same as the world mean value. The radiation hazard indices, ELCR values found in th

关键词： Radioisotopes

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Development of sorghum mutant genotypes and analysis of their agro-morphological diversity

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Research Square 2021年

作者： Takele, Abera Feyisa, Tileye Disasa, Tesfaye Institute of Biotechnology Addis Ababa University Addis Ababa Ethiopia Department of Plant Science Salale University Fiche Ethiopia Department of Microbial Cellular and Molecular Biology College of Natural and Computational Science Addis Ababa University Addis Ababa Ethiopia Department of Plant Science National Agricultural Biotechnology Research Center Addis Ababa Ethiopia

Sorghum is one of the most important cereal grains in Africa's Sub-Saharan region, used for human consumption and animal feed, but its production is hampered by biotic and abiotic constraints, necessitating genetic improvement of sorghum. The goal of this experiment was to use the ethyl methane sulfonate induced mutation technique to develop superior genotypes for sorghum production and quality for food and industry in order to achieve food security. The concentration of EMS was initially optimized by calculating LD50. Both Argity and Dekeba genotypes were treated with six different concentrations of EMS (0.10, 0.25, 0.30, 0.50, 0.75 and 1.00 %) and three different soaking periods (7, 8 and 9 hrs). The 0.25% EMS concentration at 8 hrs was chosen because it had a 50% seed survival rate and the highest frequency of mutations to generate M1 seeds. From M2 and M3, about 4000 and 2000 mutant populations were screened, respectively. For trait characterization, 190 mutated lines were selected from a mutant population of 2000M2. The 190 mutant populations and two parents were evaluated for genetic diversity, character association, and genetic divergence. For the observed quantitative phenotypic traits, analyses of variance showed substantial inter-population difference. When compared to their parent cultivars, the study mean of six treatment populations in each cultivar showed significantly superior quantitative phenotypic traits. Plant height, flowering date, maturity date, stem diameter, grain weight, and thousand seed weight varied with 81.48, 77, 42.03, 56.11, 11.44, and 96.68 % heritability in the mutant lines, according to agro-morphological characterization. The elite mutants were identified using principal component analysis based on their agro-morphological traits, while Pearson's correlation findings showed a positive correlation between yield component traits. Finally, our research allowed the identification of new promising mutant genotypes that could be tested

关键词： Seed

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Graphitic Carbon Nitride with Extraordinary Photocatalytic Activity Under Visible Light Irradiation 8th

Graphitic Carbon Nitride with Extraordinary Photocatalytic A...

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8th EAI International Conference on Advancement of science and Technology, ICAST 2020

作者： Gebreslassie, Gebrehiwot Bharali, Pankaj Gebremariam, Gebremedhin Sergawie, Assefa Alemayehu, Esayas Department of Industrial Chemistry College of Applied Sciences Addis Ababa Science and Technology University Addis Ababa16417 Ethiopia Department of Chemical Sciences Tezpur University Napaam Tezpur784028 India Department Chemistry College of Natural and Computational Sciences Mekelle University Mekelle231 Ethiopia Faculty of Civil and Environmental Engineering Jimma University Jimma378 Ethiopia

ISBN: (纸本)9783030806170

Catalytic activities of graphitic carbon nitride (g-C3N4) are restricted thanks to inadequate visible light absorption and high rate electron–hole recombination. In this work, we synthesized porous g-C3N4 using polycondensation process. Structural and physico-chemical characteristics of the prepared g-C3N4 materials were studied via XRD, DRS, PL, FTIR, Raman spectroscopy, SEM, BET and CHN elemental analyzer. The prepared samples exhibited surprising catalytic activity for the photo-oxidation of rhodamine-B (RhB) in visible light irradiation. From the fabricated g-C3N4 materials, the g-C3N4-550 showed photodegradation efficiency of 100% towards the RhB pollutant in water within 30 min. No appreciable decrease of the photocatalytic efficiency of g-C3N4 was observed up to five consecutive cycles, confirming the synthesized g-C3N4 was highly stable. Thus, this work gave a simple process for large scale production of highly visible light responsive and stable g-C3N4 materials used for environmental remediation. © 2021, ICST Institute for Computer sciences, Social Informatics and Telecommunications Engineering.

关键词： Porous materials

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Analysis of Atmospheric Air Pollutants Using Lichens as a Bio-Monitor by Calibration Free-Laser Induced Breakdown Spectroscopy Technique

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SSRN 2023年

作者： Assefa, M. Dilbetigle Chaubey, A.K. Taddesse, Awoke Asres, Yihunie Hibstie Physics Department Addis Ababa University P. O. Box 1176 Addis Ababa Ethiopia Laser Spectroscopy Research Laboratory Department of Physics University of Allahabad U.P. Allahabad211 002 India Department of Physics Debre Markos University Faculty of Natural and Computational Science P.O. Box 193 Debre Markos Ethiopia

Biomonitoring provides information on the quality of the environment or its modification and has been used as an alternative to monitoring chemical pollutants. The lichen bio-monitoring technique and calibration Free-Laser induced Breakdown spectroscopy (CF-LIBS) were used to study trace element atmospheric deposition in five areas of addis ababa city. The emission of air pollutants, mainly from anthropogenic sources, has led to the degradation of air quality. The element contents of the transplanted Epiphytic lichen were determined in the vicinity of different heavy traffic and small industry places. We identified twenty-one elements (Fe, Ti, U, V, Ni, Eu, Zr, Sr, Ba, Hf, Na, K, Sc, Si, Al, Mg, Ca, C, N, O, and H). Calibration Free-Laser induced breakdown spectroscopy and semi-quantitative methods were used to calculate the concentration of pollutants to point out the most polluted areas for the chemical analysis. Dried samples of the lichen containing heavy pollutants elements like Fe, Ti, Sr, Sc, Ba, Ni, Eu, and Zn are found, and their concentration is determined. Comparison of the elemental concentration in lichen samples transplanted in 4-kilo and science faculty compound with those the Bola airport, central bus station, and Laghar train station reveals that the science faculty compound and 4-kilo areas show a considerably higher concentration of most elements in the lichen than observed in the other areas of the city where lichen samples have been transplanted. © 2023, The Authors. All rights reserved.

关键词： Calibration

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Local Communities' and Parishioners' Perceptions on Monasteries' Forest Patch Plant Biodiversity Conservation in Northern Wollo Ethiopia

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International Journal of Forestry Research 2023年第1期2023卷

作者： Abebe Semu, Arayaselassie Bekele, Tamrat Lulekal, Ermias Coayla, Edelina Department of Biology and Biodiversity Management College of Natural and Computational Sciences Addis Ababa University Addis Ababa Ethiopia Range Ecology and Biodiversity Program College of Agriculture and Environmental Sciences Haramaya University P.O. Box 138 Dire Dawa Ethiopia Faculty of Economic Sciences Universidad Nacional Federico Villarreal Lima Peru

Both anthropogenic and climate change threaten Ethiopia's forest regions. Sacred and religious sites maintain most indigenous and native plant species. Northern Ethiopia farmed and settled for thousands of years, causing environmental damage and deforestation. This study examines biodiversity conservation perceptions and biodiversity preferences by local communities and churchgoers. Among the five monasteries in the area, two were selected based on the stated chriteria. The selection criteria for monasteries were a historical antiquity of more than 50 years and a thick forest cover of more than 10 hectares. Multistage sampling was utilized to choose sample residences. Respondents were chosen using simple random sampling and proportion to population size. Among the total population, 310 survey participants were selected. It was found that the commitment to biodiversity conservation of local people and parishioners is directly explained by age, education, the number of years in a status region, and income. It is highlighted that a higher level of education, age above 51 years, and middle-income socioeconomic status most significantly affect respondents' biodiversity engagement. © 2023 Arayaselassie Abebe Semu et al.

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