Gebrelibanos T.,Aksum University |
Assen M.,Addis Ababa Institute of Technology
African Journal of Ecology | Year: 2014
This study aimed to determine the spatial variation of topsoil properties as influenced by slope aspects and vegetation types. Three vegetation types and two slope aspects were considered. Disturbed and undisturbed samples were taken from the top soils. A two-way analysis of variance was used to test significant mean differences (α = 0.05). Results showed that contents of bulk density, total porosity, organic matter and exchangeable magnesium were significantly different with changes in slope aspect (P < 0.05). Textural classes, organic matter, available phosphorus, carbon-to-nitrogen ratio, cation-exchange capacity, per cent base saturation and exchangeable bases demonstrated significant variation among vegetation types (P < 0.05). The south-facing aspect and the grass vegetation showed higher bulk density but lower organic matter and total porosity. As a remedy for the identified problems, there is a need to undertake plantation of indigenous trees. © 2013 John Wiley & Sons Ltd.
Gebru B.,Aksum University |
Bezu S.,Norwegian University of Life Sciences
Environment and Development Economics | Year: 2014
This paper examines the adverse effect of natural resources scarcity on children's schooling and the possible gender bias of resource collection work against girls' schooling. It uses cross-sectional data on 316 children aged 7-18 years collected from 120 rural households in Tigray, northern Ethiopia. The two-stage conditional maximum likelihood estimation technique is employed to take care of endogeneity between schooling and collection intensity decisions. The results revealed that a 50 per cent increase in collection intensity reduces the likelihood of child schooling by approximately 11 per cent. However, we find no evidence of gender bias against girls' schooling. Copyright © Cambridge University Press 2013.
Mathew S.,Aksum University
African Journal of Biotechnology | Year: 2010
The paper gives an overview on the allelic variant of CYP2D6 genotype. The gene CYP2D6*3 encodes a member of the cytochrome P450 super family of enzymes. The cytochrome P450 proteins are monooxygenases which catalyze many reactions involved in drug metabolism and synthesis of cholesterol, steroids and other lipids. The protein localizes to the endoplasmic reticulum and is known to metabolize as many as 20% of commonly prescribed drugs. Its substrates include debrisoquine, an adrenergic-blocking drug; sparteine and propafenone, both anti-arrythmic drugs; and amitryptiline, an anti-depressant. The emerging application of pharmacogenomics in the clinical trials requires careful comparison with the traditional genotypic methodologies particularly in the drug metabolism area. © 2010 Academic Journals.
Mulugeta Y.,Aksum University |
Woldeghebriel H.,Mekelle University
Computational and Theoretical Chemistry | Year: 2014
The geometric and electronic structures of lead telluride clusters are investigated numerically. The result provided both vertical and adiabatic electron affinities (VEAs and AEAs) for this clusters, revealing a pattern of alternating values in which even n clusters exhibited lower values than odd n clusters up until Computations found lead telluride clusters with even n to be thermodynamically more stable than their immediate odd n neighbors, with a consistent pattern also being found in their HOMO-LUMO gaps. Analysis of cluster dissociation energies found at cube to be the preferred product of the queried fragmentation processes, consistent with our finding that cluster exhibits enhanced stability; it is a magic number species. Beyond, prefer two dimensional stacking of face-sharing lead telluride cubical units, where lead and tellurium atoms possess a maximum of fivefold coordination. The preference for sixfold coordination, which is observed in the bulk, was not observed at these cluster sizes. © 2014 Elsevier B.V.
Mengistu E.,Aksum University |
Kassa T.,Bahir Dar University
Advances in Space Research | Year: 2015
In this paper, we reported on a case study of the temporal characteristics of the Equatorial Electrojet (EEJ) and Counter Electrojet (CEJ) over Ethiopian sector during an interval on August 27, 2008 inferred from ground-based magnetometer observations. The EEJ is an intense eastward flowing electric current on the dayside along the dip equator in the equatorial ionospheric E-region between about 90-120 km. This intense current has an associated magnetic field ΔH which can produce a large enhancement on the horizontal component of the geomagnetic field. Calculating the difference between the horizontal components of magnetic perturbation (H) at the equator and off the equator, ΔH, yields information about the strength of the EEJ current. Simultaneously, the sign of the current provides us with information on the direction of current flow (when the normal eastward flow of the EEJ is reversed, the resulting current is known as the CEJ). By using data collected during an interval on August 27, 2008 from Addis Ababa, Ethiopia, observatory in conjunction with Adigrat, Ethiopia, observatory and applying the above mentioned technique, we have observed the electrojet as well as the CEJ in the sector. The electrojet has been observed between about 09:15-14:30 LT (LT: local time). The electrojet and CEJ are peaked at about 12:00 and 08:00 LT, respectively. In addition, we have also observed the CEJ between about 09:00-09:15 LT and in the afternoon about 14:00 LT. This study also presents the temporal and diurnal variations of the field on different quiet and disturbed days during an interval from September 01-19, 2008. Strongly perturbed, dimly perturbed, and almost smooth variations on the fields are observed. For example, strongly perturbed fields are observed on September 03-04, 2008 and September 15, 2008 days and smooth curves are observed between September 11-14, 2008 and September 17, 2008. © 2014 COSPAR.