Browsing by Author "Abraha, Alem"
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Item Determining the Academic English Language Needs of(Addis Ababa University, 2007-07) Abraha, AlemThe purpose of this study was to investigate the academic English language needs of computer science students at HiLCoE College. The target needs were specified in terms of the four macro skills and the most common language activities under each macro skill. Questionnaires were designed and distributed to two different groupsinstructors of computer science courses and students of computer science at the college. Interviews were conducted with the instructors and students to cross check the responses obtained through the questionnaires. With these instruments, the subjects of the study were asked to indicate the degree of importance of the macro skills and language activities to students of computer science in the college. The findings revealed that the receptive skills - listening and reading are the most important skills followed by writing and speaking respectively. The findings have also shown that the main language activities under each macro skills are: a, Listening -listening to lecture, listening to teachers’ explanation and listening to class discussion, b. Speaking- asking questions, answering questions and Participating in group discussion, c. Writing- making lecture notes, writing other assignments and writing test answers d. Reading – reading lecture notes, reading text books and reading hand outs. An analysis of the course book in use was also carried out to see whether it was relevant to the needs of the learners. It was found out that it largely fails to meet the needs of the learners in that the findings of the analysis did not correspond to the identified needs of the learners.Item The Theory of Superconductivity and Some Electron Pairing Mechanis(Addis Ababa University, 1988-06) Abraha, Alem; V.N. Mal'nev (PhD)The recent discovery of high··temperature superconductivity brought about the necessity of clal'ifying a set of questions. One of these is regarding the electron pairing mechanism. Upto now, we have a well-developed microscopic theory of the conventional supel'conductivity, the so-called BCS theory. lIs we know, the pairing of electrons in this theory is realiz!!d through the exchange of virtual phonons. This mechanism leads to the existence of energy gap in the spectrum of elementary excitations of low-temperature superconductivity. And, in the absence of magnetic field, it is known that the normal-superconducting transition is second-order phase transition. ThllS, the BCS theory gives the recipe for calculating all physical quantities of cOllventional superconductors. The situation with the high-temperature superconductivity ;s much more complex. The mechaIYism of high - Tc superconductivity is still unkonwn. This is the reason we decided to give in this pape!' the revie~1 of conventional phenomenological t,heories of superconductivity and give new formulation of BCS theory ;,/hich is b,lsed on retarded thermal Green's function method. We a 1 so attempted to analyze the ava i1 ab 1 e eXperimenta 1 data on hi gh - T c and some of the pairing mechanisms discussed in the literature. We finally Pt'oposed a mode 1 ~/hich can execute hi gil-temperature superconduct; vity where .' '? electrons are paired by the exchange of virtual plasmons which can be OOset'ved in some specially prepal'ed thin films