Browsing by Author "Tesfaye, Kassahun"

Now showing 1 - 3 of 3
  • No Thumbnail Available
    Item
    Determination of the Levels of Pb, Cr, Zn, Cu and Al in Soil from Selected Garage Site in Addis Ababa, Ethiopia
    (Addis Ababa University, 2020-02-02) Tesfaye, Kassahun; Tessema, Merid (PhD)
    Both natural and human activities adds heavy metals to soil, natural activities have a little effect on soil pollution, however soil pollution mainly causes from anthropogenic activities of humans that lead to heavy metals toxicity into the soils. Garages are one of the major sources of increase in heavy metal concentration in soils of Addis Ababa, Ethiopia. Three garage sites were selected for the study, which include; Zenebework (Z.W), Amanuel (A) and Kotebe (K). Heavy metals in the soil samples at 0-10 cm depth were collected. After proper sample pretreatment, the type and volume of reagents to be used, digestion temperature and digestion time were optimized. Then using the optimized conditions sample preparation was made and levels of metals such as Lead (Pb), Zinc (Zn), Chromium (Cr), Copper (Cu) and Aluminium (Al) in each soil were determined by microwave plasma atomic emission spectrometry (MP-AES). The accuracy of the optimized procedure was evaluated by analyzing the digestion of the spiked samples with standard solution and the percentage recoveries varied from 86% to 112%. The mean concentration of metals obtained in each site at 0-10 cm depth by MP-AES (mg/kg) were; (Z.W; Zn: 422 ± 31.8, Cr: 58 ± 6.8, Cu: 71 ± 6.1, Al: 47601 ± 2350), (A; Zn: 657 ± 42, Cr: 146 ± 12.8, Cu: 307.5 ± 14.4, Al: 16132 ± 664), (K; Zn: 447 ± 20, Cr: 57 ± 4.5, Cu: 188 ± 6.1, Al: 17486 ± 953.6). The levels of metal concentration in the soils from these experimental sites were higher than the recommended limits given by World Health Organization (WHO). In these study; Lead (Pb) is below the detection limit.
  • No Thumbnail Available
    Item
    Molecular Characterization of Ethiopian Indigenous Goat Populations: Genetic Diversity and Structure, Demogrphic Dynamics And Assessment of the Kisspeptin Gene Polymorphism
    (Addis Ababa Universty, 2016-06) Mekuriaw, Getinet; Tesfaye, Kassahun
    Ethiopia lies within the earliest geographic center for the dispersal of livestock into the African continent. It therefore comprises a unique repository of livestock genetic diversity in the continent. However, information relating to the origin and divergence of domestic goats in the NOIth-East African region, and Ethiopia in particular, remains unknown despite the availability of genomic tools to assess the same. Here, the complete mitochondrial DNA D-loop region of 309 individuals representing \3 Ethiopian indigenous populations of goats was sequenced to investigate the maternal historical demographic dynamics of Ethiopian indigenous goats, Similarly, genotype data were generated from 14 populations by the 50K Caprine SNP CHIP array to investigate the genetic diversity and structure of Ethiopian indigenous goats, The Chinese Cashmere, Cashmere-Ibex hybrid and the wild Swiss Alpine Ibex populations were also included as outgroup for comparison, In addition, analysis of polymorphism of the KISS I gene and its association with litter size, and haplotype and patterns of linkage disequilibrium (LD) analysis were conducted in exon regions of the kisspeptin gene of Gondar and Woyto-Guji goat populations. A total of 173 and 242 Sanger sequences were employed for further analysis of exonl (1210 bp) and exon2 (325 bp) regions of the kisspeptin gene, respectively, Sequencing of the mtDNA, 174 variable sites that generated 231 haplotypes were observed in the D-loop region of mtDNA sequences and these haplotypes defined two haplogroups lacking a phylogeographic structure but with a high genetic diversity. In a combined analysis of reference haplotypes representing the six globally defined Caprine haplogroups revealed out two haplogroups to be A and G, with the former being the most predominant. The lack of phylogeographic structure and a weak population differentiation (overall PST = 0.0245) suggest extensive gene flow amongst indigenous Ethiopian goats. In the gcnome wide survey, high genetic diversity (HE :0: 0.35) but low level of genetic differcntiation among the populations is revealed. Thc 14 populations were grouped into six clusters and none of them was spccific to one population or geographic region. Interestingly, population phylogenetic analysis did not support the classification of Ethiopian goats based on their agro-ecological location, associated production system and phenotypic family as suggested previously, but differentiated the Kaffa goat from the rest of 13 Ethiopian goat populations. Based on the admixture and phylogenetic network analyses, the 14 Ethiopian goat populations can be re-grouped into seven goat types. On the other hand, polymorphism analysis of the KISS I gene revealed five complete substitutions and 15 polymorphic sites in both exon regions. The overall average HE was 0.18863±0.21 for exonl and 0.031 55±0.0 I for exon2. Among detected polymorphic sites only four SNPs contributed 18%-31 % multiple birth. Similarly, a total of29 and three haplotypes were detected in exonl and exon2, respectively. The overall haplotype diversity was 0.8703 for exon I and 0.0703 for exon2. Lowest (0.083 for Woyto-Guji and 0.081 for GondaI' goats) and modest (0.656 for Woyto-Guji and 0.635 for GondaI' goats) average estimates of R2 and ID'I were obtained in LD decay analysis in exonl, respectively, and most of the R2 and ID'I values suffer floor and ceiling effects. The neutrality tests showed significant and negative values of Fs for Woyto-Guji (Fs = -8.098) and for GondaI' " goats (Fs = -12.08); whereas, the Tajima's D test was positive and non-significant. Overall, there was high goat population dynamics that causcd to have highest level of population admixture. The KISS I gene polymorphism analysis showed importance of the gene for multiple birth in Ethiopian goats and can be suggested for marker assisted selection breeding program. Key words: Ethiopia, Genetic diversity, Haplogroup, High density SNP Chip, Indigenous goat, Kisspeptin gene, Population expansion, Neutrality test
  • No Thumbnail Available
    Item
    Recurrent Neural Network
    (Addis Ababa University, 2011-01) Tesfaye, Kassahun; Bekele, Berhanu (PhD)
    The purpose of the study was to investigate Neural Networks in general and Recurrent Neural Network in particular. The investigation was to construct a model that shows the complex data processing of these Neural Networks and their functions in a simple way by using Artificial Neural Networks. Therefore, in order to carry out this task, Perceptron, Feed Forward and Recurrent Neural Networks, and the basic concept of Biological Neural Networks, which are among the contents of this paper, are very important. From a biological point of view, Neural Networks are networks of biological neurons. Basically, they are networks of sensory, motor and associative neurons functionally, and axon, cell body and dendrites structurally. Now, when an external or internal signal reaches the sensory neuron through the receptors, then it passes to the motor neuron through the associative neuron within the central nervous system. Since motor neuron has connection with the brain, then it immediately fires through the command that comes from the brain. This means that it gives response for that particular signal. In this paper we extend these concepts to mathematical model by using the concepts of mathematics. For instance, a Heaviside function is a simple mathematical model of Neural Network. On the other hand, Recurrent Neural Network consists of the graphG=(N,A)and a family of formal neuronsG=(V,E)-(X,Y,a,S) each associated to one of the Vertices IEVThis paper also provides details about the types of Neural Networks present in human being and also provides details about the Artificial Neural Networks. This paper also presents some Applications of Neural Networks