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  Subjects -> SCIENCES: COMPREHENSIVE WORKS (Total: 374 journals)
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SINET : Ethiopian Journal of Science
Number of Followers: 5  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0379-2897
Published by African Journals Online Homepage  [261 journals]
  • Improved Principal Component Analysis and Linear Discriminant Analysis for
           the Determination of Origin of Coffee Beans using

    • Authors: Endale Deribe Jiru , Berhanu Guta Wordofa , Mesfin Redi-Abshiro
      Pages: 1 - 25
      Abstract: In this work an improved Principal Component Analysis (pca) method is used for better determination of geographical origins of Ethiopian Green Coffee Beans. In the commercially available and widely employed pca methods the dataset is commonly normalized using Z-score procedure, which reduces the influence of the spread of data (or dispersion degree differences) on principal components (pcs). In the improved method, a new normalization procedure is introduced with the aim to improve the spread (dispersion) of data points around the mean. The pcs computed from the improved procedure could significantly better reflect information of the original dataset. The dispersion degree information in the original dataset was retained relatively much by using the improved pca than the Z-score-based pca. The improved pca was then used to identify the most discriminating variables corresponding to the coffee samples and, based on that, Linear Discrimination Analysis (lda) model was developed to classify and predict samples. The recognition and prediction abilities of the improved pca and lda at regional level respectively were 95.7% and 94% (using Chlorogenic Acids (cga s) content), 91% and 97% (using Fatty Acids (FA) content), 99% and 100% (and using the combined cga and FA contents). Mehari et al. (2016, 2019) reported recognition and prediction of the pca, they applied on the same dataset, at regional level were 91% and 90% (using cga s content) and 95% and 92 % (using fas content), respectively. The result reveals that the newly introduced method is superior and the best discriminations of coffee beans were achieved. The combined analysis of cga and fa concentrations is a useful tool for the determination of origin of coffee beans, and we recommend that the concerned bodies should use it to address the characterization, classification and authentication of Ethiopian coffee beans according to their geographical origins.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.1
      Issue No: Vol. 45, No. 1 (2022)
       
  • Vegetables for building molecular models

    • Authors: Zewdu Gebeyehu, Rajeev B Dabke
      Pages: 26 - 32
      Abstract: An exciting classroom activity involving the construction of molecular models and building hybrid orbitals is presented in this paper. Basic molecular geometries were built by connecting different types of vegetables using bamboo skewers. Vegetable of different shapes were used to describe the hybridization of atomic orbitals. This exercise is suitable for high school and undergraduate chemistry students. The activity helps students to apply Valence Shell Electron Pair Repulsion (VSEPR) theory to envisage the basic shapes of molecules and to conceptualize the hybridization of the atomic orbitals
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.2
      Issue No: Vol. 45, No. 1 (2022)
       
  • The influence of parent rock, mining and processing technologies on the
           industrial quality of kaolin concentrate –case study from Bombowha
           kaolin, Ethiopia

    • Authors: Tilahun W/Mariam , Worash Getaneh
      Pages: 33 - 47
      Abstract: Bombowha kaolin deposit is a primary deposit formed mainly through weathering of granite and pegmatite. This research was designed to evaluate the influence of parent material, mining practices and processing technology on the quality of processed kaolin. Geochemical, mineralogical, and technological properties of kaolin were analyzed and field observations conducted to evaluate the influence. Samples of the parent rocks, kaolin deposit, Run-Of-Mine, and processed kaolin were analyzed for their geochemistry, mineralogy and physical properties. Results show that the kaolin derived from pegmatite has better quality (high alumina, low silica, better plasticity, low coloring elements and others) than the granite-derived one. The poor quality of the granite-derived kaolin is ascribed to its incomplete kaolinization as evidenced by the presence of minor halloysite. The geochemical analysis of the Run-Of-Mine shows close similarity to that of the parent granite demonstrating severe dilution during mining, hauling and storage of kaolin ore. The high pit-wall angle (80-85°), the rheologically weak overburden, old excavation machinery and unsystematic delineation of mineable portion of the deposit contributed to high level of dilution. The properties of processed kaolin show the wet processing method brought substantial improvement in the quality of the kaolin (Al2O3 increased by nearly 98% and SiO2 decreased by 36% with respect to the Run-Of-Mine). Had the feed kaolin ore not been diluted, the kaolin concentrate would have been better than what is achieved through the adopted processing method. Systematic mine design, selective mining, and graded stockpiling of kaolin ore are advised for better quality kaolin concentrate.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.3
      Issue No: Vol. 45, No. 1 (2022)
       
  • User resistance in post enterprise resource planning implementation phase

    • Authors: Temtim Assefa Temtim Assefa
      Pages: 48 - 60
      Abstract: User resistance in post Enterprise Resource Planning (erp) implementation phase is one of the main causes for failure of erp systems. Existing research identified different factors that cause erp failure in the post erp implementation phase. However, existing research is fragmented without strong theoretical base. The main objective of this study is to identify factors that cause user resistance in the post erp implementation phase using innovation resistance theory as a theoretical lens. The study used causal research design as a research method. Data was collected using Google’s online form. The empirical data from this research revealed that risk barriers and usability barriers as main factors that increase user resistance in the post erp implementation phase. The research also developed and validated data collection instruments to use innovation resistance theory for empirical investigation of user resistance in the post erp implementation phase for other researchers. It has also practical implication for managers what intervention to undertake so as to increase success of erp system implementation.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.4
      Issue No: Vol. 45, No. 1 (2022)
       
  • Trends in the occurrence of Helicobacter pylori infection in Arada
           Sub-City: A 5-year retrospective study.

    • Authors: Tamrat Birru Haile , Tegenu Gelana Tiki
      Pages: 61 - 68
      Abstract: Helicobacter pylori infection remains a major public health problem in Ethiopia. This retrospective study aims at determining the prevalence of H. pylori infection over a period of 5 years, from 2016 to 2020 among dyspeptic patients at nine Health Centers of Arada sub-city, Addis Ababa. Data were collected from the patients record books of the nine Health Centers. At the health centers a stool antigen test is most often used than a serology antibody test, because stool antigen test is more specific and detects only an active infection. Chi-square analysis was employed to identify associations between variables. A P-value of <0.05 was considered significant. In the present study, the overall prevalence of H. pylori was 49.2%. The prevalence was higher among patients of age  60 years and above (59%); whereas it was lower in the age category of 15 to 29 years (43%). No association was observed between H. pylori infection and the sex (gender) of the studied cases.  However, statistically significant increments in H. pylori cases were observed over the five year study periods.  It can be concluded that the overall prevalence of H. pylori was 49.2% and there were no associations between sex (gender) and H. pylori infection. The authors would like to recommend the health centers to use stool antigen test and to provide an awareness for the study population.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.5
      Issue No: Vol. 45, No. 1 (2022)
       
  • In vitro evaluation of marker assisted conversion of adapted sorghum
           varieties into Striga hermonthica resistant versions

    • Authors: Teklay Abebe Teklay Abebe , Gurja Belay , Taye Tadesse, Gemechu Keneni
      Pages: 69 - 85
      Abstract: Striga has long been recognized to infest staple food crops like sorghum in Ethiopia. This study was designed to introgress Striga-resistance genes into popular and farmer-preferred varieties through marker-assisted backcrossing and to assess resistance based on Striga germination stimulant activity inagar-gel assay (aga). The experiment was arranged in completely randomized design with four replications. Genotypes performance, heritability and genetic advance were analyzed and Germination rate was measured. The progeny showed significant genetic variation for maximum germination distance (mgd), germination rate (gr), and germination index (gi). The mean mgd ranged from 0.0 mm to 29.45 mm and gr ranged from 0.0% to 72.38%.Of the 118 backcrossed lines, 22.9% showed less than 10 mm of mgd and gr of <30%, revealing provision of low germination stimulant/strigolactones production (lgs). There were significant positive (r = 0.4-0.81) correlations showing the roles of these parameters as selection criteria in breeding for resistance. The existence of higher heritability (h2b = 77-83%) and genetic advance (ga = 62-93%) for the germination parameters indicated possibilities for improving resistance against Striga through selection. Genotypes that carry different qtls showed different capacity of producing Striga germination stimulants in the aga. The combined effect of two qtls (lgs2_SBI-05_60404021 and lgs_3_60629027) at a time showed lower Striga germination stimulant activity and better field resistance indicating existence of possible cumulative effects. Thus, the study showed that marker-assisted backcrossing for transfer of lgs qtls from donor into popular and farmers preferred cultivars has the potential to enhance tolerance/resistance to Striga in sorghum.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.6
      Issue No: Vol. 45, No. 1 (2022)
       
  • Population density, feeding and, reproductive ecology of rodents from
           Alemsaga Priority State Forest and adjacent farmlands

    • Authors: Bewketu Takele, Mesele Yihune , Afework Bekele
      Pages: 86 - 96
      Abstract: A study on population density, feeding, and reproductive ecology of rodents from Alemsaga Priority State Forest and the adjacent farmlands was conducted from July 2018-September 2020. Live and snap traps were used for capturing rodents from the study area. The Capture-Mark-Release method was employed to estimate the population size and respective density of rodents. Snap traps were used to capture rodents for body measurement and stomach content analysis. Embryo count was carried out from 64 pregnant females. Data were computed using descriptive statistics and compared with chi-square. Lophuromys simensis, Arvicanthis abyssinicus, Desmomys harringtoni, Mastomys natalensis, Stenocephalemys albipes, Rattus rattus, Arvicanthis dembeensis, Mus musculus, and Acomys cahrinus were recorded from the six habitats. The result indicated that a total of 1140 and 171 individuals were trapped in the study area with live and snap traps, respectively. The average population density of rodents was 47.4 h-1. The highest density was recorded in bushland habitat (75.1 h-l) while the least was in Carissa land (32.2h-l). In terms of species, L. simensis showed the highest density (111.65 h-l) whereas A. cahrinus was the lowest (1.7 ha-1). The overall densities of rodents were 224.82 ha-1 and 162.93 ha-1 during the wet and dry seasons, respectively. The total rodent biomass in the study area was 160,495 g. The number of embryos counted ranged from 4-12 and 2-8 during the wet and dry seasons, respectively. However, there was no statistical significance between the two seasons (χ2 = 0.74, df=1, p> 0.05). Plant matters constituted a higher proportion of stomach contents (64.4%) compared to animal matters (13.2%). Generally, Alemsaga State Forest harbors rodent species with high density and biomass. Proper conservation of the area will contribute to the betterment of species density and biomass.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.7
      Issue No: Vol. 45, No. 1 (2022)
       
  • Weak idempotent rings

    • Authors: Dereje Wasihun, Tilahun Abebaw, Yibeltal Yitayew, Venkateswarlu Kolluru
      Pages: 97 - 104
      Abstract: In  this paper is to introduce the notion of weak idempotent rings as a generalization of Boolean like rings. We obtain many formal properties of the class of weak idempotent rings and furnish certain examples of the class of weak idempotent rings. Furthermore, we obtain the properties of completely prime ideal and left and right completely primary ideals of weak idempotent rings.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.8
      Issue No: Vol. 45, No. 1 (2022)
       
  • Zeros of a two-parameter family of harmonic quadrinomials

    • Authors: Oluma Ararso Alemu, Hunduma Legesse Geleta
      Pages: 105 - 114
      Abstract: In this paper, we determine the number of zeros and the zero inclusion regions of a two-parameter family of harmonic quadrinomials. We also determine a curve that separates sensepreserving and sense-reversing regions for these families of quadrinomials. Our work makes practical and effective use of the work of Wilmshurst, Khavinson, Dehmer, and also Bezout’s Theorem in the plane.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.
      Issue No: Vol. 45, No. 1 (2022)
       
  • Determining regions of higher extinction risk occurrences in South African
           cycads

    • Authors: Bamigboye Samuel O.
      Pages: 115 - 124
      Abstract: Extinction crisis in South African cycads has been very high in recent times. This study used comprehensive distribution records of cycads that occurred in South Africa.  The records obtained from the South African national herbarium named South African National Biodiversity Institute (sanbi) through the herbarium sheets were used to determine the regions of higher extinction crisis in South Africa. The threat status of the herbarium taxa was obtained from iucn 2019 version and was analysed. Threats to these taxa were extracted from iucn and the numbers of taxa facing each threat were determined to unravel the prominent threats. The herbarium records were used to construct a species distribution map for all the cycads in South Africa and another map for Critically Endangered and Extinct South African cycads. This study revealed that regions of high species richness for South African cycads are not the same as regions with highly threatened and extinct South African cycads. Prominent threats found in this plant group are also the major threats causing extinction crisis in the highly threatened and extinct cycads that occurs in few provinces in South Africa. This study therefore recommends that conservation efforts for South African cycads should be intensified in the hotspots of highly threatened and extinct South African cycads identified in this study to further mitigate extinction crisis of South African cycads.
      PubDate: 2022-04-27
      DOI: 10.4314/sinet.v45i1.10
      Issue No: Vol. 45, No. 1 (2022)
       
 
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