626 research outputs found

    Coastal development and pollution impact on the distribution of macrobenthic communities along the eastern coast of the Gulf of Suez (Egypt)

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    The configuration for the eastern side of the Gulf of Suez was studied over 241 km from Ras Mohammed to Ras Sudr including 35 station. Litters, tar balls and aged oil patches aggregated in considerable amounts on the beach and shore line of the middle part due to the oil spills from off-shore oil wells. A large reef flat in the shallow intertidal waters exists at stations 1 and 2 (Ras Mohammed, Protected area) and spars coral patches are less frequent at the Stations from 7 to 13. Density and diversity of marine benthos were higher on hard and cobble bottoms compared to muddy sand and sandy substrates. The assemblages of the benthic fauna are dominated by the gastropod Courmya (Thericium) vulgata; the bivalve Brachiodontes variabilis, and the barnacles Chthamalus stellatus, Balanus amphitrite and Tetraclita rubescens. The distribution of the algal cover in the intertidal region shows high abundance of the brown algae, Sargassum latifolium; padina pavonica and Cystoseira trinodis rather than the green and red algae. These species are found in both polluted and unpolluted areas. The changes in benthic structures in the study area depend not only on the state of pollution but also on the type of substrates

    SEISMIC PERFORMANCE OF BUILDINGS WITH MULTIPLE UNDERGROUND STORIES

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    This thesis is dedicated to investigate the seismic performance of moment-resisting frame steel buildings with multiple underground stories resting on shallow foundations and to evaluate the current common modeling assumption of analyzing the seismic response of these buildings fixed at the ground surface. The role of the Soil-Structure Interaction (SSI) phenomenon in the seismic design of buildings was extensively reviewed from the structural and geotechnical perspective. The rocking behavior of shallow foundations can greatly affect the seismic response of the supported structures. Thus, one of the main objectives of this thesis is to develop and validate a practical and reliable modeling approach suitable for analyzing the cyclic response of 3D shallow foundations with special attention to their moment-rotation behavior. A parametric study that involved evaluating the nonlinear seismic response of five, ten and fifteen story moment-resisting frame steel buildings resting on a flexible ground surface, and buildings having one, three and five underground stories was performed. It was found that SSI can greatly affect the seismic performance of buildings in terms of the seismic storey shear and moment demand, and the deformations of their structural components. Although most building codes postulate that SSI effects generally decrease the force demand on buildings but increase the deformation demand, it was found that, for some of the cases considered, SSI effects increased both the force and deformation demand on the buildings. iii The SSI effects generally depend on the stiffness of the foundation and the number of underground stories. SSI effects are significant for soft soil conditions and negligible for stiff soil conditions. It was also found that SSI effects are significant for buildings resting on flexible ground surface with no underground stories, and gradually decrease with the increase of the number of underground stories

    The Quiet Role of OAU In Africa\u27s Liberation

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    Arabic Language Online Learning System

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    In recent times, there has been a strong push for higher education institutions to offer more online courses to cater for students who otherwise would be denied university education. While this may benefit the many distance education students, the take-up rate of totally online education by current on-campus students remains uncertain. At the same time, many lecturers have started to design and develop online teaching material for their courses; many do so without the support of their employer which is the university that they work in. The purpose of this study is two-fold. Firstly, to gain an insight into how UUM's (Universiti Utara Malaysia) students perceive online Arabic learning and to examine their readiness and willingness to make the shift from conventional classroom learning to online learning with no face-to-face contact. Secondly, to develop an online learning system for teaching Arabic language so that teaching can be made more effective and at the same time enjoyable. Students can learn Arabic language via the online system anytime, anywhere and at anyplace

    The Effect of Electronic Marketing on the Quality of Tourism Services in Libya

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    The paper investigates enterprises in the Libyan tourism industry and their perception of the role of e-marketing in developing the industry. It considers enterprises that do not apply e- marketing, the problems they face and the benefits they would gain from an e-marketing programme. In relation to this the importance of e-marketing and the extent to which theory is followed is examined. The paper explores what should be done to develop e-marketing for tourist enterprises and how to implement strategic plans for the industry to increase its market share to enable it to compete in the international market place. The tourism industry is important to Libya’s economy and greater consideration should be given to its development and, in particular, to e-marketing. This is especially the case for small and medium-sized tourism enterprises (SMTEs) since most industrial sectors depend on these composing 50% privately owned and the rest full or part government owned

    Acute toxicity of four heavy metals to Sphaeroma walkeri and Ciroiana bovina (Crustacea:Isopoda)

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    The median lethal concentrations (LC50) of two Isopoda species exposed to each tested metal (Cu. Co, Cd and Zn) in static tests for different exposure periods are quite variable depending on the tested metal The LC50 values for Sphaeroma walkeri after 24 hours exposure to Cu and Co were estimated graphically to be 11.20 and 7.00 mg/1 respectively. The correspoding values for Cirolana bovina exposed to Cu, Co, Cd and Zn were 3.60, 11.0, 3.80 and 4.80 mg/1 respectively. For 2 days the LC50 of S. walkeri exposed to Cd was 5.60 mg/l, but it was 10.10 mg/l for 3 days exposure to Zn. After prolonged exposure the LC50 values decreased proportionally with the exposure duration of the test the percentages of surviving animals demonstrated a progressive decrease with increasing concentratins as a main factor from the analysis of variance (ANOV A). The sensitivity of adult S. walkeri exposed to the four heavy metals for different exposure times ranked: Cd>Co>Zn>Cu. Cirolana bovina appeared to be more sensitive to Cu. Cd and Zn than to Co. Species in order of increasing sensitivity is C. bovina more than S. walker

    THE CONTROL OF APRICOT SEED DORMANCY AND GERMINATION BY LOW TEMPERATURE TREATMENTS

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    Objective: Freshly harvested seeds of “Local” apricot variety were found to be dormant and did not germinate at all. A specific low-temperature stratification treatment was required to overcome seed dormancy. The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C cold stratification (CS). Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds. Methods: For stratification treatments, the seeds with removed endocarp were mixed with moistened sand. Afterward, they were subjected to a period of stratification at 5°C. Seeds were stratified in pots of 30 cm×40 cm. Stratified seeds were regularly irrigated once per week. To prevent the water loss during stratification upper surface of pots was covered by a sack. The following stratification was applied for apricot variety: CS for 0, 3, 6, 9, 12, and15 days in 1998 and 1999 years for “Local” variety. Results: Apricot seeds required a CS of about 15 days for “Local” variety to reach maximum germination and normal seedling growth. Moreover, when stratification period was prolonged, some of the chemical constituents of apricot seeds were increased and other was decreased. Therefore, it can be suggested that breaking of dormancy is coincided with several changes in different chemical constituents of seeds. Some of these materials increased (total, reducing and non-reducing sugars, total free amino acids, total indoles, and total and conjugated phenols) and other materials such as free phenols which decreased at seed germinations. Conclusion: The most effective temperature for breaking seed dormancy, germination, and seedling growth was 5°C CS. Increased seed germination percentage was recorded when the period of stratification prolonged. Seedling developed from stratified seeds had better growth than those developed from non-stratified seeds

    Detection of Trypanosoma brucei gambiense and T. b. rhodesiense in Glossina fuscipes fuscipes (Diptera: Glossinidae) and Stomoxys flies using the polymerase chain reaction (PCR) technique in southern Sudan

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    Ethanol-fixed entire bodies of the tsetse fly, Glossina fuscipes fuscipes, and unidentified stable flies, Stomoxys spp., collected from near Juba town, southern Sudan, were  tested for Trypanozoon trypanosomes infections using polymerase chain reaction (PCR) technique for the first time in Sudan. The crude target DNA sequences were extracted by incubation of entire flies in Nonindet PCR template buffer containing proteinase-K. The DNA amplification sets of conditions were adjusted for each pair of primers employed. The oligonucleotide primers used included TBR1-2, SRAA-E, SRAB537-B538 and TgsGPFOR-REV. The results showed that 74.4% of G. f. fuscipes and 39.36% of Stomoxys spp. were infected with Trypanozoon trypanosomes. Out of the 117 examined G. f. fuscipes, 46.2, 24.8, 35.04, 17.09 and 10.26% were due to T. b. gambiense (TgsGPFOR-REV), T. b. rhodesiense (SRAA-E), T. b. rhodesiense (SRA3537-3538), mixed infection with T. b. gambiense and T. b. rhodesiense and T. b. brucei, respectively. However, infections in Stomoxys spp. of 2.13 and 37.2% were due to T. b. rhodesiense and T. b. brucei, respectively.Key words: Glossina fuscipes fuscipes, T. b. gambiense, T. b. Rhodesiense, vectoral capacity, infection rate, PCR technology

    Tests of Storage Rack Channel Columns with Rear Flanges

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    An experimental study was performed to investigate the ultimate strength and modes of failure of axially loaded channel rack columns with rear flanges. A total of 16 column specimens fabricated by press-brake forming method were tested up to failure. The material properties of the column specimens were determined using standard tensile coupon tests. The deformation and stress behavior of the tested columns were monitored using displacement transducers and strain gauges. The effects of column slenderness ratio, thickness, perforation, and end conditions on the column ultimate strength and mode of failure were studied. The test failure loads were compared to the ultimate load predictions of the 2001 AISI North American Specification. The comparison showed that the AISI procedure overestimates the failure load, which suggests that the proportioning of the cross-sectional dimensions of the lipped channel sections with rear flanges has a direct effect on the capacity of the columns
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