Code-mixing of Arabic and English in a university science-teaching context : frequency, grammatical categories, and attitudes

This study explores a language contact phenomenon in the monolingual Arabic-speaking country of Libya. It investigates aspects of Arabic-English code-mixing in a university scientific and technical teaching context. While the language policy in Libya is one which promotes the maintenance and purification of Arabic, and there are ideological barriers against the use of foreign languages (Al-Galley, 1989), English is a guest language that plays an important role in attaining some educational goals, especially at post-secondary levels. For the purpose of this investigation, code-mixing is defined as: the verbal behavior of embedding English words, phrases, sentences, or constituents in Arabic-based instruction. The present study addressed itself to three questions: (1) To what extent does the phenomenon of code-mixing exist in the language of instruction ? (2) Which grammatical categories are susceptible to being rendered by English ? and (3) What are the general trends of students' attitudes toward code-mixing ? (Abstract shortened by UMI.

GENETIC DIVERSITY ASSESSMENT OF IN VITRO IRRADIATED TOMATO (LYCOPERSICON ESCULENTUM MILL.) USING SCOT MARKERS

Tomato (Lycopersicon esculentum Mill.) is considered the major and important globally vegetable crops especially in Egypt. Tissue culture techniques have facilitated the induction of mutant which helps in crop improvement. The mutation induction in vegetative crops through tissue culture may be the optimal method to improve these crops. Tomato explants of Idkawy Egyptian cultivar were cultured in vitro on MS medium supplemented with 0.2 mg/L BAP. The resulted plantlets were irradiated with different gamma radiation doses (50, 100, 150, 200 or 250 Gy) and the survival and mean of shoot length decreased as gamma radiation doses increased. The survival percentages of irradiated plantlets were ranged from 78.75% with 50 Gy dose to 18.75% with 250 Gy dose, while the shoot length values were decreased by a rate of 2.71 cm for dose 50 Gy and 1.2 cm for 250 Gy dose. The ten SCoT primers amplified a total of 114 amplicons with a range from 4 with SCoT-4 primer to 18 amplicons with SCoT-5  primer with an average of 11.4 amplicons per primer, The radiation specific markers were ranged from one fragment with SCoT-1 and SCoT-2 primers, SCoT- 5 two fragments with primer to five fragments with SCoT-3 and SCoT-33 primers

Mathematical formulae for neutron self-shielding properties of media in an isotropic neutron field

The complexity of the neutron transport phenomenon throws its shadows on every physical system wherever neutron is produced or used. In the current study, an ab initio derivation of the neutron self-shielding factor to solve the problem of the decrease of the neutron flux as it penetrates into a material placed in an isotropic neutron field. We have employed the theory of steady-state neutron transport, starting from Stuart's formula. Simple formulae were derived based on the integral cross-section parameters that could be adopted by the user according to various variables, such as the neutron flux distribution and geometry of the simulation at hand. The concluded formulae of the self-shielding factors comprise an inverted sigmoid function normalized with a weight representing the ratio between the macroscopic total and scattering cross-sections of the medium. The general convex volume geometries are reduced to a set of chord lengths, while the neutron interactions probabilities within the volume are parameterized to the epithermal and thermal neutron energies. The arguments of the inverted-sigmoid function were derived from a simplified version of neutron transport formulation. Accordingly, the obtained general formulae were successful in giving the values of the experimental neutron self-shielding factor for different elements and different geometries.Comment: 14 pages, 5 figures, 1 graphical abstract, 73 references, and 2 tables, include improvement of illustration and story-telling writing styl

The Attenuation Capability ofSelected Steel Alloys for Nuclear Reactor Applications

Neutronsand gamma ray attenuation of different steel grades (SS304, SS304L, SS316L, SS430, a modified high manganese-nitrogen austenitic stainless steel, and developed cobalt-free Maraging steel) was measured to study their capability to be used as nuclear reactor materials. The hardness and microstructure of the studied steel alloys were carried out using Vickers hardness and optical microscope respectively.Neutron and gamma rays measurements were carried out using a narrow beam transmissions geometry method. Measurements and calculations of gamma ray attenuation coefficients were carried out at energies 238.63, 338.28, 583.19, 911.2, 968.97, 1173.23, 1332.49, and 2614.51 keV. The transmitted gamma rays were detected by the Hyper Pure Germanium detector (HPGe), while, the neutron flux emitted from 241Am-Be neutron source was used to measure the neutron removal cross section for both slow and total neutrons. The transmitted beam of neutrons was measured under a good geometric conditions using 3He counter.A good agreement between experimental data of mass attenuation coefficients and theoretical results calculated by the WinXcom computer program (version 3.1) was obtained

Stimulated perturbation on the neutron flux distribution in the mutually-dependent source-to-absorber geometry

The complexity of the neutron transport phenomenon throws its shadows on every physical system wherever neutron is produced or absorbed. The Monte Carlo N-Particle Transport Code (MCNP) was used to investigate the flux perturbations in the neutron field caused by an absorber. The geometry of the present experiment was designed to reach a simulation of an isotopic neutron field. The neutron source was a ${}^{241}$AmBe with the production physics of neutrons is dependent only on alpha-beryllium interaction and is independent of what happened to the neutron after it was generated. The geometries have been designed to get a volume of uniform neutron densities within a spherical volume of radius 15 cm in every neutron energy group up to 10 MeV. Absorbers of different dimensions were placed within the volume to investigate the field perturbation. Different neutron absorbers were used to correlate the phenomenon to the integral cross-section of the absorber. Flux density inside and outside the absorber samples was determined, while the spatial neutron flux distribution produced by the AmBe source without an absorber was taken as a reference. This study displayed that absorbers of various dimensions perturb the neutron field in a way that is dependent on the absorption and scattering cross-sections, particularly in the neutron resonance region. Unlike the simple picture of reducing the number density of neutrons, the perturbation was found to influence the moderation of neutrons in the medium, significantly above 1 MeV.Comment: 10 pages, 13 figures, 26 reference