College of Natural and Computational Sciences

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2, 4, 6-Tris (N-Salicylidenehydrazino) S-Triazine and its Copper (II) Complex-Synthesis, Characterization and Antimicrobial Screening
(Addis Ababa Universty, 2008-07) Haile Kiros; Raju V.J.T. (Professor)
A new tripodal ligand 2, 4, 6-Tris (N-Salicylidenehydrazino)-s-Triazine (L) was synthesized by the condensation of salicylaldehyde with 2, 4, 6-tris-(hydrazine)- s-triazine(THSTZ) in acetonitrile. Copper complex of the ligand was synthesized in chloroform-methanol 50% v/v medium. The ligand and the metal complex were characterized by employing spectral (IR,Uv-Vis,AAS, NMR), conductance and magnetic susceptibility studies. The purities of the compounds were established by TLC. The studies support formation of stable metal complex corresponding to the formulae: [Cu(II)LH2O] .4H2O. Conductivity measurement indicates that the complex is a non-electrolyte. Spectral and Magnetic data suggest dibasic ONN donor behavior of the ligand towards Cu(II). Square planar geometry for Cu2+ complex has been proposed. The ligand, metal complex and related compounds were screened for antimicrobial activities against Escherichia coli, Pseudomonas eruginosa, Staphylococcus aureus and Bacillus cereus bacteria by employing tetracycline as test control agent. The result showed that both the ligand and the metal complexes were inactive, while the ligand precursor (THSTZ) and the metal salt (CuCl2.2H2O) were active. As such derivatization and the complexation can help in detoxication purposes. Key words: 2, 4, 6-Tris (N-Salicylidenehydrazino)-s-Triazine (L), tripodal ONN donor, Cu2+ complex, Square planar geometry, antimicrobial.
2d Geometry of Quadrapole Magnetic field Lines from Neutron Star and Associated Radiation Pressure
(Addis Ababa University, 2011-06) Girma, Melkameshet; Wetro, Legesse (PhD)
In this thesis we have derived the vector potential to determine the analytic expressions for the magnetic eld of dipole and quadrupole components of neutron star, we develop the eld line equations and the magnetic eld line geometry of both dipole and quadrupole terms. The magnetic eld varies with time and as well as the induced electric eld. As a result the neutron star can generate electromagnetic radiation. This electromagnetic radiation has pressure. We have derived the radiation pressure at any distance r out side of the surface of the neutron star
A 2D Monte Carlo Investigation of Static and Dynamic Properties of Ring polymer
(Addis Ababa University, 2015-02) Admasu, Ashenafi; Yergou, Tatek (PhD)
Monte Carlo simulation technique has been used to investigate the static properties and translocation characteristics of ring polymers in two dimensions. Each chain consists of exible linkage between monomers forming a closed loop. We consider the unbiased translocation process of the ring where the polymer translocates purely due to thermal uctuations. The average escape time has been analyzed as a function of chain length N. And we found that, the polymer escape time of the ring polymers having a length N < 100, also has a scaling behavior N where is more closer to 1 + 2 in which is the Flory exponent of value 3/4 in 2D and 3/5 in 3D. Such scaling is also the scaling behavior of the unbiased long linear chains. We study the static property of the small cyclical polymer chains by calculating the mean-squared radius of gyration Rg. Bond uctuation method (BFM) is implemented to study both characteristics of the particular ring polymers
2D Spin-Dependent Electron Scattering by Nanomagnets
(Addis Ababa University, 2012-02) Senbeta, Teshome
The 2D scattering problem of an electron by a magnetized nanoparticle is solved in the Born approximation with account of the dipole - dipole interaction of the magnetic moments of electron and nanomagnet. The scattering amplitudes in this problem are the two-component spinors. They are obtained as functions of the electron spin orientation, the electron energy and show anisotropy in scattering angle. The initially polarized beam of electrons scattered by nanomagnet consists of electrons with no spin flipped and spin flipped. The majority of electrons with no spin flipped are scattered by small angles. This can be used as one method of controlling spin currents. 2D spin-dependent scattering of slow unpolarized beams of electrons by charged nanomagnets is analyzed in the Born approximation. The obtained scattering lengths are larger than those from the neutral nanomagnets approximately by one order. It is shown that for particular parameters of the system it is possible to polarize completely the scattered electrons in a narrow range of scattering angles. The most suitable system for realization of these effects is 2D Si electron gas with immersed nanomagnets. The 2D spin-dependent electron scattering by the linear chain of periodic nanomagnets with account of the diffraction effects was studied. This effect takes place in 2D electron gas with immersed nanomagnets. By tuning a distance between nanomagnets, it is possible to obtain diffraction maximum of the scattered electrons at scattering angle, which corresponds to complete spin polarization of electrons. The total diffraction scattering lengths are proportional to N2 (N is a number of nanomagnets). The proposed system can be an efficient separator of spin polarized currents
3d Modelling for Urban Cadasteral Regestration,Management and Administration; The Case of Bahir Dar Town Ethiopia
(Addis Ababa Universty, 2016-06) Hamid, Ahmed; Berihan, Getachew (PhD)
High rate of Population growth, coupled urbanization and industrialization results for high demand for land. In order to increase availability of land, the government of Ethiopia has introduced the construction of multipurpose buildings which allows vertical expansion rather than horizontal. Due to this mode of expansion there is a need to establish a land tenure system which considers the use and registration of multipurpose buildings in 3D environment. In Ethiopia, using aerial photography for cadastral mapping is not a new thing for the processes of extraction of 2D cadastral layer but most of the time it is not seen using for 3D cadastral registration system. Method of feature extraction in 3D environment using aerial photograph is cheaper than that of LIDAR. 2D cadastral and property registration system cannot solve the problem related to building height and was difficult to standardize building construction, even if it has been employed for a long period of time. 2D cadastral registration system is not able to clearly indicate the property right of individuals having multi-purpose buildings. Due to this it is difficult to register, manage, and visualize their institute condition for decision making and for a given applications such as infrastructure development. This study is intended to examine the applicability of Aerial photo and CGA script for automated 3D objects modeling, design cadastral information system for commonly owned residential building and commercial centers, examine legal and institutional aspects of 3D property information and representation system for land registration, management, administration, urban planning and decision making process in Bahir Dar town by applying 3D GIS techniques. The existing 2D cadastral registration system was carefully assessed and the gaps are well identified prior to propose a new registration system. The ESRI 3D city engine module was used to reconstruct the multipurpose buildings after carried out photogrammetric processes. CGA rule was written for each textures such as wall, roof, road, façade, window and door to produce an automated 3D urban model. From the study it is found that the existing cadastral registration system in Bahir Dar land management and development office does not consider the registration of multipurpose buildings. Due to this a new registration system was proposed to incorporate multipurpose buildings in the future cadastral registration processes. It was also found that a 3D model cadaster supports better in managing increased demand of land and building constructions. Key words: 3D model; Cadaster; aerial photo; CGA rule; Façade; Registration; Management Administration, Bahir Dar
9,9-Disubstituted Fluorene-Based Polymers: Preparation and Characterization
(Addis Ababa Universty, 2009-07) Hussen, Ayalew; Mammo, Wendimagegn (Professor)
A family of conjugated polymers based on 9,9-disubstituted fluorenes and cyanovinylenes were reported. The polymers were synthesized by employing a slightly modified Suzuki coupling polymerization reaction and condensation polymerization utilizing the Knoevenagel reaction. The resulting polymers showed good solubility in chloroform. The energetic positions of the band edges were determined by cyclic voltammetry. The synthesized polymers were characterized by using spectroscopic techniques such as UV-Vis and 1H- NMR. The presented polymers exhibited emission of blue to red colors.
AB Initio calculation of Optical Absorption and Optical Gap of Silicon Nanocrystallites
(Addis Ababa University, 2007-07) Gugsa, Derese
The electronic and optical properties of hydrogenated silicon nanocrystals have been investigated both in the ground- and in an excited-state configuration, through different ab-initio techniques. The presence of an electron-hole pair leads to a strong interplay between the structural and optical properties of the system. The aim of this work was to investigate the optical properties of hydrogenated Si nanoclusters (H-Si-nc) that has recent experimental interest for photonic applications. The optical absorption spectra of small SinHm nanoclusters are computed using a linear response theory within the time-dependent local density approximation (TDLDA). The TDLDA formalism allows the electronic screening and correlation effects, which determine exciton binding energies, to be naturally incorporated within an ab initio framework. We examined that the calculated excitation energies and optical absorption gaps to be in good agreement with experiment
Ab-Initio Calculations of High Pressure Phase Transition, Structural and Electronic Properties of Bexznl _Xs (X = 9.00, 0,41, 0.66 and 1.00) Ternary Alloys
(Addis Ababa University, 2013-06) Fufa, Fatana; Mazher, Javed(Prof)
In this piece of research, we have performed self-consistent ab-initio calculations to study the structural and e lectronic properties of BexZnl -xS mixed crystals in the various low and high pressure crystallographic phases of thc alloy. The zinc blend phase and rock salt phase of compositionally variant zinc-bery llium-sulfide have been used for the calc ul ations of' structura l and electronic properties within the local density approximation of density fu nctional theory. The concent rat ion of Be (X) changes f'rom 0.00, 0.41 , and 0.66 to 1.00 in the al loy. Super cells (54 atoms) of the all oys are constructed and fully relaxed. Al l the values of ternary and binary alloy lattice constants, bulk modulus and cnergy band gap are calculated on these relaxed structures. Our results are comparable to the contemporary theoreti cal and experimental observations. Our values for the structural parameters obtained in the LOA approximation are also in good agreement with the experimental values. We have also observed direct band to indirect band gap (r ..... r) ..... (r ..... X) by increasi ng beryl lium concentrations along with some LOA related under estimation s of gap widt hs. For al l the samples of the alloy, high pressure phase tran sitions are found to present and reported in the range of' giga pascal pressures. At the same time, increase of hardening of the al loy is reported due to Be content and the bulk modulus correspondingly increases in the alloy. We have also analyzed the concentration related effects on electronic density of states and bowing parameters.
The Abo Blood Group and Plasmodium Falciparum Malaria in Awash, Metehara and Ziway Areas, Ethiopia.
(Addis Ababa University, 2008-07-05) Tekeste Zinaye; Petros Beyene (Professor)
The study aimed at investigating the relationship between blood group type and severe disease in P.falciparum malaria in three Ethiopian malaria endemic localities. A total of 210 cases of malaria (70 severe and 140 uncomplicated) and 190 healthy controls participated in the study. In the severe malaria category, there were 25 (35.7%), 15 (21.4%), 14 (20%) and 16 (22.9%) blood group A, B, AB and O patients respectively. Blood group O was the dominant blood type in both uncomplicated malaria (45.7%) and healthy controls (41.6 %). As compared to the uncomplicated malaria, a case of severe malaria was almost twice as likely to be of type A as to be of type O (O vs. A, odds ratio 0.42, 95% confidence interval 0.2007- 0.8789), and more than twice as likely to be of type B as to be of type O (O vs. B, odds ratio 0.38, 95% confidence interval 0.1638-0.8973), and in both cases the difference was statically significant (P=0.019 for O vs. A; P= 0.02 for O vs. B). Furthermore, individuals with severe malaria were about seven fold less likely to be of O as to be of type AB (O vs. AB, odds ratio 0.19, 95%; P=0.0005). There was significantly low mean hemoglobin concentration in the severe malaria patients than the uncomplicated malaria and healthy controls (P <.0001). Although the mean parasite density in individuals with severe malaria was higher than in those with uncomplicated malaria, the difference was not significant (P=0.35). Blood group O malaria patients had high mean hemoglobin concentration than those with blood group A, B, or AB, with significant difference only between blood group O and A (P=0.012), and blood group O and B (P=0.050). Furthermore, blood group O malaria patients were found to have a relatively low mean parasite density than patients with either blood group A or AB, but there was no significant difference in both cases (P=0.55 for O vs. A; P= 0.90 for O vs. AB) .The study revealed that on the basis of depressed hemoglobin concentration, patients with blood group O were less prone to severe P.falciparum malaria as compared to patients with blood groups A or B.
Absorption Coefficient and Dielectric function of direct Band Gap silicon Nanocrystallites
(Addis Ababa University, 2007-07) Gebrehiwet, Hagos
Silicon is an ubiquitous electronic material and the discovery of strong room temperature luminescence from porous silicon in 1990 raised hopes it may find a new lease of life in the emerging field of optoelectronics. First, the luminescence was shown to be emitted from nanostructures in a porous silicon network. Later the same emission was seen from silicon nanocrystallites and the concept of a silicon quantum dot emerged. A number of different models have been proposed for the origin of the light emission. Some involve interface states between a silicon nanocrystallite and a surrounding shell, while others consider the effect of quantum confinement in an indirect bandgap semiconductor. In order to clarify the influence of morphological properties, such as size or shape, of a silicon nanocrystallite on its optical properties, calculations of optical absorption coefficient and dielectric function of silicon nanocrystallites as a function of effective silicon nanocluster size (diameter) and photon energy were attempted using k.p method. To conclude, the work presented in this thesis gives support to the quantum confinement effect in explaining the optical properties of band gap nano-sized silicon below 10nm, as well as highlighting the importance of calculating optical parameters of silicon nanocrystallites to understand optical properties in the luminescence process
Abundance and Diversity of Top Soil Earthworms in Relation to Chemical Use in Golden Rose Agrofarm, Tefki Area, Ethiopia
(Addis Ababa University, 2007-07) Mergia, Addisu; Mengistou, Seyoum (PhD)
Despite the current environmental controversies, flower farms are becoming hot areas of investment in Ethiopia. Golden Rose Agro Farm is one of the largest, and the pioneer, flower industries in the country. To study the abundance and distribution of top soil earthworms in relation to chemical use in the farm, a total of 208 1mx1 m quadrates were marked on the ground in 10 randomly selected greenhouses. Similarly, 208 quadrates were marked in the outside chemical-free farm for comparison. Soil was then dug to a depth of 15 cm in all of the marked quadrates and hand-sorted to collect top soil earthworms. Eight plastic buckets, each filled with soil at 15 cm depth, were taken and 15 adult worms originally from chemical-free soil were introduced in to each and all were put in the greenhouses, some under chemical treatment and some free for comparison. Worms from the rose farm were also transferred to chemicalfree soil and changes were observed after 20 days. Earthworms were taxonomically identified to genus level using taxonomic keys. There was strong statistically significant variation in abundance of both adult and juvenile top soil earthworms between the two farms (P < 0.01, α=0.05). Out of the 75 adult worms introduced into the chemical-treated buckets, 98.7% (74) were dead, and in the Chemical-free buckets, out of the 45 worms originally introduced, about 95.6% (38 adult and 5 juveniles) were recaptured. About four genera of earthworms were identified in the study area, but majority of them belong to the genus Eiseniella and Dendrobaena. Seasonal variation in number and distribution of earthworms was also observed in the study. Chemical use in Golden Rose Agrofarm strongly affected abundance and distribution of top soil earthworms in the area
Abundance of Rodent on Different Land Management Intervention in Simien Mountains National Park, North Ethiopia
(Addis Ababa University, 2018-10-04) Deksios Derbe; Jebessa Habte (Professor)
This study deals with the abundance rodents in different land management intervention. Overgrazing is one of the conservation challenges of the Simien Mountains National Park . Overgrazing has been devastating the fragile afro-alpine Ecosystem. The objective of this study was to identify habitat quality and abundance of rodent by recording the new rodent hole and the common mole rat hill between May, 2017 (wet season) and January and February 2018 (dry season), assessed thirteen transect lines in average 2-4 km each. In more rodents captured were investigated in six major sites (within twelve) sub sites and the grids were established within representative vegetation covers.During dry season, five species of rodents Lophuromys flavopunctatus, Arvicanthis abyssinicus, Stenocephalemys grisiecauda, Otomys typus,Mus mahomet and one species of insectivores, Crocidiura baileyi, were recorded. There was significance variation in habitat quality among different land management intervention fresh rodent holes and common mole rat hills (p<0.002 and P<0.003), respectively. ANOVA analytical test result also indicated that rodents’ distribution were significantly different with different land management such as moderate, slightly grazed and overgrazed habitats across afro-alpine ecosystem of Simen Mountains National Park. There was also variation in species abundance in grazed, unglazed and completely grazed land management system. The highest abundance was Arvicanthus abysinicus 56% six major sites; in twelve subsets no rodent was recorded in overgrazed Wezahla one low abundance C.baileyi 0.6%. Density of rodents highest in Alchemilla plant species 8/km2and 0 in overgrazed Hypericum revolutum plant species. There was significant different in rodent abundance (P<0.04) in different land management intervention. In general, grazing pressure were negatively affected the habitat quality of rodent and common mole rats' abundances. . Therefore, to reduce overgrazing, it is recommended to strength habitat conservation to gain habitat quality. To follow participatory conservation reduce overgrazing allowing rotational cut and carry system with limited time bound exclude core area and it should be applied in local bases.
Abundance, Composition and Habitat Association of Rodents in Wonji Sugarcane Area; Ethiopia
(Addis Ababa University, 2006-06) Takele Serekebirhan; Bekele Afework (Professor); M.Balakrishnan (Professor)
A study on the ecology of rodents was carried out in Wonji Sugarcane Plantation from August 2005 to March 2006. Three trapping grids were randomly selected in the sugarcane plantation based on the growth stage of the cane as- immature sugarcane plant (ISP), young sugarcane plant (YSP), and old sugarcane plant (OSP). An additional grid was selected from bushland area outside the sugarcane plantation. A total of 629 captures were made in 2940 trap nights. Out of these, 557 individuals represented eight species of rodents: Mastomys natalensis, Arvicanthis dembeensis, Arvicanthis niloticus, Stenocephalemys albipes, Pelomys harringtoni, Mus mahomet, Mus musculus, and Rattus rattus. The remaining 72 individuals represented two insectivore species; Crocidura flavescence and Crocidura fumosa. Abundance of species varied in different growth stages of the sugarcane plantation and bushland area. There was seasonal difference in the abundance of the rodents. However, species composition was the same in all the three growth stages of the sugarcane plants and in bushland area. Variation in trap success with different growth stages of the of sugarcane plantations was significant. All age groups were represented in the population of most species. Breeding was seasonal for most of the species. The pest status of rodents in the sugarcane plantation was assessed. Analysis of the stomach contents of snap trapped rodents from the plantations showed sugarcane fibers that confirm the pest status of rodents in the sugarcane plantation while monocot plants were dominant in rodents captured from bushland area. Population estimation using minimum number alive (MNA) showed decline in each trapping session.
Abundance, Distribution and Insecticide Resistance of Anopheles Mosquitoes (Diptera: Culicidae) and Malaria Transmission Intensity in Relation to Agro-ecology in Sekoru District, Southwestern Ethiopia
(Addis Ababa University, 2017-06) Ejeta, Desta; Tekie, Habte(PhD)
Malaria is a leading cause of morbidity and mortality in several sub-Saharan African countries. Environmental/ecological changes due to anthropogenic activities are among the determinant factors for malaria transmission. Agricultural practices are among anthropogenic activities that contribute to malaria incidence and transmission. Understanding association of ecological changes due to anthropogenic activities on mosquito species composition, abundance, distribution, dynamics, insecticide resistance and malaria transmission intensity is important to plan and implement effective vector control intervention strategies. Thus, the aim of this study was to investigate species composition, abundance, distribution and infectious rate of Anopheles mosquitoes and their knockdown resistance (kdr) status in relation to agricultural practices. A longitudinal entomological study was conducted from January to December 2015 in Sekoru District, southwestern Ethiopia. Anopheles mosquito larvae and adults were collected using different methods from villages with different agro-ecology. The mosquitoes were identified to species level using standard keys. Molecular identification of Anopheles gambiae complex and detection of knockdown insecticide resistance (kdr) was conducted using species-specific PCR and allele specific PCR techniques. Moreover, Plasmodium circumsporozoite protein was detected for both Plasmodium falciparum and P. vivax using Enzyme-linked Immunosorbent Assay (ELISA). Eight Anopheles mosquito species (Anophelesarabiensis,An. demeilloni, An. squamosus, An. garnhami, An. christyi, An. pretoriensis, An. longipalpis and An. marshallii) were identified, of which An. arabiensis was the predominant species (46.2%; n=715). The highest number of Anopheles mosquitoes (66%; n=1019) was collected from the irrigated village. The xvi infection rate of An. arabiensis was higher in the irrigated village (10.8 infective bites/person/month) as compared to rain fed agriculture practicing village (5.99 infective bites/person/month) and human settlement village (zero infective bite). Anopheles gambiaes.l. larvae were the predominant (57.4%) larval species identified. The highest larval density (2.12 larvae/dip) was recorded from the irrigated village. Only West African kdr mutation (L1014F) was detected with an allelic frequency of 83.88%. The distribution and frequency of kdr allele were significantly associated with study villages (X2=133.85, df=2, P <0.001). The kdr allele frequency was 95%in the irrigated village, 78.87%in village with rain fed agriculture, and 3.89% in the human settlement village. In conclusion, Anopheles mosquito abundance, distribution, infection rate and insecticide resistance were significantly associated with agro-ecology. Agro-ecological practices need to be considered in the management of Anopheles vectors of malaria. Keywords: Anopheles mosquitoes, Agro-ecology, Insecticide resistance, Irrigation, Larval habitats, Malaria, Sekoru District
Ab–initio Calculations of Structural and Electronic Properties of a BexZn1-xSe Ternary Alloy
(Addis Ababa Universty, 2012-06) Mulualem, Getasew; Mazher, Javed (Professor)
We have used the ab-initio SIESTA code within the framework of DFT, LDA method to calculate the structural and electronic properties of BexZn1-xSe alloy for different compositions x = 0.0, 0.33, 0.66, and 1.0. The system is modelled in various possible configurations using a large 54-atom supercell. It is noteworthy to mention that the determination of structural and electronic properties of a BexZn1-xSe ternary alloy at x = 0.33 and 0.66 have not been reported earlier to the best of our knowledge. We analyze composition effect on lattice constants, bulk modulus, pressure derivative, bandgap, and density of states. Deviations of the lattice constant from Vegard’s law and the bulk modulus from linear concentration dependence are observed. It was deduced that increasing the Be composition in the alloy increases the hardness of the materials. In addition, the calculated band structures showed that the bandgap undergoes a direct-to-indirect transition at the composition of 0.84. The bandgap is found to vary non-linearly with Be composition. Using the approach of Bernard and Zunger, the microscopic origins of bandgap bowing is also explained. It is concluded that the energy bandgap bowing is primarily due to volume deformation effect. Furthermore, the structural phase transformations of ZnSe under high pressure are also studied by similar method. It is found that ZnSe undergoes a first-order phase transition from the zinc blende structure to the rock salt structure at approximately 13.75 GPa. The ground state properties of the phases of ZnSe are also calculated. Our results are in good agreements with experimental observations.
An Academic Resource Centre in the University of Malawi: It’s Need and a Plan for Its Development, Together With Prototype Databases
(Addis Ababa University, 1993-06) Duncan Vote; Neelameghan A. (Professor)
The Academic Resource Centro (ARC) discussed in this thesis is an information facility designed to provide information support for the efficient and effective performance of the statutory and public service functions of the University of Malawi and its associated institutions and organizations including related government departments, pastorals, research centers etc. It is conceived as an information center forming an integral part of the university college and institutions associated with higher learning and research in Malawi. The ARC will utilize viable information technology in conjunction with manual methods. Pr-planning studies undertaken include: a review of trends in information technology (IT), a survey of a accessibility to IT in \ Malawi, an assessment of the existing information support systems of the University of Malawi and their inadequacies in relation to the information and data needs of the variety of users of the academic and research community and the related government and para statal organizations . Based on the findings, plans to develop the ARC and steps to implement the plans are proposed. The ARC is conceived as a networking of -viiinformation systems within the university and the associated institutions as well as of appropriate institutions in the country and abroad. The ARC plan outlines the requirements in terms of manpower, systems design and implementation. Libraries and information centers which could participate in the ARC network are mentioned. A set of integrated databases consisting of : bibliographic records; information on . \ curriculum development, academic prospectus etc; profiles of experts and institutions; of databases and information systems; of ongoing projects and researches in the university of Malawi, Government and other selected research institutions, is presented as prototypes for the databases to be developed at the ARC. Data entry guidelines are also provided. Training facilities for IT personnel are not adequate in the country and it has led to under utilization of equipment and heavy reliance on vendor service support for the systems. Some suggestions are made in overcoming this problem. Introduction of IT in libraries, documentation and information centres in the country is slowly gaining ground and currently is largely being applied in special -viiilibraries and to a certain extent in academic libraries as well. However, IT applications to generate information products and services is currently limited to word processing and in-house bibliographic database management. Emerging its, such as CD-ROM, networking and desktop publishing, are yet to be widely used in Malawi. The need for developing national databases to capture and disseminate information generated in the country is emphasized.
An Academic Resource Centre in the University of Malawi: It’s Need and a Plan for its Development, Together with Prototype Databases.
(Addis Ababa University, 1993-05) Duncan, Vote; Neelameghan, A. (Prof.)
The Academic Resource Centre (ARC) discussed in this thesis is an information facility designed to provide information support for the efficient and effective performance of the statutory and public service functions of the University of Malawi and its associated institutions and organizations including related government departments, parastatals, research centres etc. It is conceived as an information centre forming an i ntegral part of the university college and institutions associated with higher learning and research in Malawi. The ARC will utilize viable information technology in conjunction with manual methods. Pre-planning studies undertaken include: a review of trends in information technology (IT), a survey of accessibility to IT in Malawi, an assessment of the existing information support systems of the University of Malawi and their inadequacies in relation to the information and data needs of the variety of users of the academic and research community and the related government and parastatal organizations. Based on the findings, plans to develop the ARC and steps to implement the plans are proposed. The ARC is conceived as a networking of i nformat ion systems wi thi n t he university and the associated institutions as · well as of appropriate institutions in the country and abroad. The ARC plan outlines the requirements in terms of manpower, systems design and implementation. Libraries and information centres which could participate in the ARC network are mentioned. A set of integrated databases consisting of: bibliographic records; information on curriculum development, academic prospectus etc; profiles of experts and institutions; of databases and information systems; of ongoing projects and researches in the University of Malawi, Government and other selected research institutions, databases to is be presented developed as prototypes for the at the ARC. Data entry guideliness are also provided .Training fa c ilities for IT personnel are not adequate in the country and it has led to underutilization of equipment and heavy reliance on vendor service support for the systems. Some suggestions are made in overcoming this problem. Introduction of IT in libraries, documentation and information centres in the country is slowly gaining ground and currently is largely being applied in special libraries and to a certain extent i n academic libraries as well. However, IT applications to generate information products and services is currently limited to word processing and in-house bibliographic database management. Emerging Its, such as CD-ROM, networking and desktop publishing, are yet to be widely used in Malawi. The need for developing national databases to capture and disseminate information generated in the country is emphasized.
Acaia Byssinica Hochst. Exbenth: Pod and Seed Characteristics, Germination Physiology and Potentials for Seedling Establishment on Degraded Land
(Addis Ababa University, 1998-06) Haile, Berhank; Negash, Legesse (PhD)
This study was conducted on pod and seed characteristics, gel1ninalion physiology as well as the potentials of Acacia abyssinica Hochst. ex Benlll ssp. abyssinica fOI' growing on degraded land. Mature pods of A. abyssinica were collected ji'01/l Irees found in alld around Addis Ababa (wilhin a radius of 35 km). One hundred pods pel' tree were collected ji'on, 26 diJ)erellt frees. Comparison of the lIIeans of pod lenglh, pod widlh and seed nUlllber per pod showed Significant dij)erences (p < 0.05) among samples obtained ji'om the dij)erent localities. Pod lenglh, pod width and number of seeds per pod ranged between 3.7 and 14.4 cm, 1.0 and 2.7 CIII and 2 and 13 respeclively. 11lere was no significant correlation benveen pod lenglh and widlh. Pod lenglh and number of seeds per pod were significanlly correlated (p ~ O. OOO). On the other hand, pod widlh and number of seeds pel' pod were negalively cOI1'elaled (p ~ 0.000). Seeds collecled ji'om 35 dij)erent h'ees were made into 17 bulks (each containing 1000 seeds). 111e weight oflhe bulks ranged ji'om 74.01 to 116.11 g. There were significant dij)erences (p ~ O. OOO) among Ihe mean weights of the 17 seed bulks. E.Dects of gibberrelic acid (GA;I, indole-3-aceclic acid (lAA) and kinetin wilh concenh'alions ranging ji'01n 1IJ' M to 11J7 JIIi on percentage gennination and radicle length of chemically scarified seeds ofA. abyssinica were exall/ined None of Ihe plant growth regulators significantly increased Ihe total percenlage gel1l1ination of seeds as compared to the control. Gennination percentage decreased Significantly at higher concenh'ations of fAA (IIJ' ,vi and 10-' Ai) and kinetin (I (f' ill!). 1AA at 11J' }.i delayed genllination for aboul a week as compared to the other concenh'alions of the same, Ihough 63% of the seeds genllinated wilhin 10-15 days after incubalioll. GA, (at 11J' ill!) Significantly increased radicle length, while 1AA at 10-' 1'v1, 1IJ'M and 11J7 ivi significantly decreased the radicle length as call/pared 10 the confrol. The investigation on the potential of Ihe species for growing on degraded land involved the growing of seedlings (GA, 10-' }v1 h'eated and Ihe conh'ol) in plastic bags in Ihe greenhouse. Soil samples ji'Oln degraded land were collecled ji'om geomorphicolly different locations ji'om an area co 4 km' along Ihe road on Ihe l'vfodjo-Zeway road, at aboul 81 km soulh of Addis Ababa. Soil samples that served as a control were collected ji'01l/ places in and orollnd Addis Ababa where A. abyssinica is currently found growing. Gel1ninants ji'om 10-' JIIi GA, and the conh'ol were plan led in bolh types of soils and were left 10 grow in Ihe greenhouse fOI' 12 weeks. All the seedlings slllvived until ha/vest. Chemical and physical analyses of the soil samples were conducled in Ihe National Soils Laborato/y in Addis Ababa. The results of the analyses indicate that 10talnih'Ogen, organic carbon and available phosphorus were Significantly higher (p < O. 05) in the soils collecled ji'om places where A. abyssinica is cun'enlly grolVing than those ji'om Ihe deg/'Qded land On fhe other hand pH, No, K, Co, and CEC were found Significantly higher (p ~ 0.00) ill the soils collectedjimll degraded land The JIIeall vollies of plant height. IIIlmber ofbrallches. IIl1l1/ber of leaves. shoot dry weight alld root dry weight were fOlllld to be sigllificalltly higher ill the controls. FroJII the resllits. it cOllld be cOllelllded that: (I) the presellce of hard seed coats is the most ill/portallt factor inhibitillg gel7nillalioll ill seeds of A. abyssillica; (2) provided that seeds are carejilily scarified (chemically or mechanically), no gennination stimulators are required for obtaining maximum percentage germination; and (3) the slllvival (IIntii hmvesl) of the seedlillgs ill soils collected ji'om degraded lalld cOllld illdicate that A. abyssillica has the potelllials for growillg ill degraded land provided that the minimllm moistllre reqllirements of the species is met.
Acceptance and Use of E-Library Services in Ethiopian Universities: The Case of Addis Ababa and Adama Universities
(Addis Ababa University, 2010-07) Ali, Abinew; Beshah, Tibebe (PhD)
The introduction of new information and communication technologies in libraries during the last two decades has altogether changed the concepts of libraries where library patrons need not necessarily go to the library physically since the library services and resources are no longer confined to the walls of the physical library. However, for these e-library services to be utilized effectively and efficiently, library end users must accept and use them. This study was mainly conducted to empirically investigate the determinants of elibrary end users acceptance and use in academic libraries within Ethiopian context. The study had applied the SO-UTAUT technology acceptance model which is appropriate in a library context. Cross sectional survey research method was used to capture the data. Questionnaire survey was employed to collect data from both Adama University and Addis Ababa University postgraduate students and academic staffs. SPSS and PLS graph beta testing software were used to analyze the data. Hence, Descriptive statistics and Structural Equation Modeling techniques using PLS were applied for analysis. The study found out performance expectancy as a major determinant factor which demonstrated the most significant contribution (36.2%) on behavioral intention to use elibrary services. Moreover, behavioral intention has shown to be the core determinant factor (40.2% contribution) for the actual usage behavior. Awareness has demonstrated a significant moderating effect on relevancy and facilitating condition constructs. The SO-UTAUT model has been proved to be valid in Ethiopian context, since it can explain 22.2% of the variance on behavioral intention, 29.9% of the variance on behavioral usage and 52.2% of the variance on expected benefits of e-library services in the users’ acceptance and use behaviors of the services.
Accessing Databases Using Amharic Natural Language
(Addis Ababa University, 10/6/2020) Legesse, Beniyam; Assabie, Yaregal (PhD)
Nowadays, day to day activities of human beings is highly dependent on the information distributed in every part of the world. One major source of the information, which is the collection of related data, is the database. To extract the information from the database, it is required to formulate a structured query language which is understood by the database engine. The SQL query is not known by everyone in the world as it requires studying and remembering its syntax and semantics. Only professionals who study the SQL can formulate the query to access the database. On the other hand, human beings communicate with each other using natural language. It would be easier to access the content of the database using that natural language which in turn contributes to the field of natural language interface to the database. Since in many private and public organizations, peoples are performing day to day activities in Amharic language and many of them are not skilled in formulating structured query language, it would be better if there is a mechanism by which the users can directly extract information from the database using the Amharic language. This research accepts questions that are written in Amharic natural language and converts to its equivalent structured query language. A dataset which consists of an input word that is tagged with the appropriate output variable is prepared. Features which represent the Amharic questions are identified and given to the classifier for training purpose. Stemmer, Morphological analyzer, and pre-processor prepare the input question in the format required by the classifier. To identify appropriate query elements, Query Element Identifier uses the dictionary which is prepared by applying the concept of semantic free grammar. The query constructor constructs the required SQL query using these identified query elements. A prototype called Amharic Database querying system is developed to demonstrate the idea raised by this research. Testers from different departments having different mother tongue language test the performance of the system.

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