356 research outputs found

    An Electrodynamics Solver for Moving Sources

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    An Electrodynamics solver for moving sources is introduced. The main challenges and formulation are highlighted. The solver enables the simulation of fields for sources undergoing arbitrary motion. Two examples of uniformly moving current sources are provided to correlate the numerical solver computations with theory, based on the solution of Maxwell's equations and the relativistic transformation of the electromagnetic fields

    Editorial

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    Effect of salinity degree of injected water on oil recovery from carbonate reservoir

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    32-37Water injection is considered the most successful and widespread secondary recovery method. Low salinity water injections is a well-established and proved technique for water flooding application in sandstone rocks to enhance the recovery efficiency; where the water salinity is adapted to a certain degree to extract the highest amount of oil from a reservoir. Reserve-estimation statistics show the significance of oil reserves in carbonate reservoirs, hence this work deals with the carbonate rocks where water flooding may fail due to many reasons, and the most common one is fractures existence in the carbonate rocks. This work applied the water injection for six carbonate (limestone) core samples from Belayim Formation of Middle Miocene age that extracted from an Egyptian offshore oil field in the Gulf of Suez. This carbonate facies is hard, vuggy, fragmented, dolomitic, and highly saturated with oil and considered a good reservoir. Relative permeability test was carried out to investigate the reservoir response in terms of recovery efficiency hence residual oil saturation, when flooding the reservoir with waters having different salinity ratios. Results showed an increase in recovery efficiency for all the tested samples, on applying the low salinity water injection, where all the relative permeability curves displayed wettability modification/alteration toward water wetness properties

    Beneficial effects of voluntary over forced exercise on skeletal muscle structure and myokines’ expression

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    Background: Myokines, a group of small proteins — mainly cytokines, are released by myocytes during muscular contraction and proved to have many biological effects locally or at systemic levels. The main objective was to study the morphological alterations and myokines expression in rat gastrocnemius muscle following forced compared to voluntary muscle contraction. Materials and methods: Thirty-six adult male Wistar rats were divided into three groups: control, voluntary exercise and forced swimming regimen. The experiment last for 3 weeks. The weight of rats and serum corticosterone levels were recorded. The gastrocnemius muscle samples were processed for histological and immunohistochemical study of different myokines. Results: The mean weight of rats showed no statistical difference between groups. Corticosterone level significantly increased after forced exercise. Voluntary exercise muscle fibres appeared hypertrophied with prominent transverse banding and dominating satellite cells. Forced exercise muscle showed atrophied widely spaced muscle fibres and inflammatory cell infiltrate. Voluntary exercise significantly increased optic density of interleukin 6, macrophage inhibitory and brain derived neurotrophic factors, whereas the forced exercise group showed significant decrease in their optic densities. The optic density of vascular endothelial growth factor significantly decreased in the forced exercise group. Forced exercise could be harmful to the skeletal muscle fibres and it decreases the secretion of important myokines. Further, forced exercise significantly increases the serum corticosterone level. Conclusions: The use of exercise for the attainment of healthy life style or in psycho- or neuro-therapy should follow a thoroughly studied programme for welfare of human health

    Transactions Briefs__________________________________________________________________ An Efficient Architecture for Multi-Dimensional Convolution

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    Abstract-This paper presents modified parallel architectures for multidimensional ( -d) convolution. We show that for two-dimensional (2-d) convolutions, with careful design, the number of lower-order 2-d convolutions can be reduced from nine to six with a computation saving of 33%. Moreover, the original speed of the computations is not affected. The proposed partitioning strategy results in a core of data-independent convolution computations, and can be generalized to the -d convolution. The resulting very large scale integration networks have very simple modular structure, highly regular topology, and use simple arithmetic devices

    Viability of laser cleaning of papyrus: Conservation and scientific assessment

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    There has been a growing interest in laser cleaning applications for a variety of organic materials such as paper, parchment, textiles, and leather during the last decade. However, archaeological organic materials, notably papyrus, have rarely been investigated. This contribution examines whether removal of burial encrustation can be justified in view of its short-term and long-term effects on the substrate. To examine this, tests using mock objects have been performed. Using artificially soiled and archaeological papyrus samples, optimization of laser cleaning parameters using a picosecond laser (1064 nm, various operating conditions) was attempted. Optimization was based on colorimetry, optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and cellulose degree of polymerization data, both before and after accelerated degradation. In papyrus, there is no clear damage threshold, and substrate degradation can always be observed and is comparable in treated (cleaned) and untreated (soiled) objects. Therefore, the decision on whether to clean papyrus using lasers is predominantly based on aesthetic and treatability (e.g. need for consolidation) criteria

    Protective effect of some plant oils on diazinon induced hepatorenal toxicity in male rats

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    AbstractEnvironmental pollution and exposure to environmental pollutants are still some of the major global health issues. Pesticides have been linked to a wide range of health hazards. The toxicity of pesticides depends on several factors such as its chemical properties, doses, exposure period, exposure methods, gender, genetics, age, nutritional status and physiological case of exposed individuals. Medicinal plants, natural products and nutrition continue to play a central role in the healthcare system of large proportions of the world’s population. Alternative medicine plays an important role in health services around the world. The aim of this study was to investigate the effect of olive, sesame and black seed oils on hepatorenal toxicity induced by diazinon (DZN) in male rats. The experimental animals were divided into nine groups. The first group served as control. The second group was exposed to DZN. The third group was treated with olive oil and DZN. Rats of the fourth group were subjected to sesame oil and DZN. Rats of the fifth group were exposed to black seed oil and DZN. The sixth, seventh and eighth groups were supplemented with olive, sesame and black seed oils respectively. Rats of the ninth group were treated with corn oil. Levels of serum alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, gamma glutamyl transferase, total bilirubin, creatinine, blood urea nitrogen and malondialdehyde were significantly increased in rats exposed to DZN. Moreover, levels of serum glutathione and superoxide dismutase were significantly decreased. Several histopathological changes were observed in the structures of liver and kidney due to DZN exposure. This study showed that these oils attenuated the physiological disturbances and histopathological alterations induced by DZN intoxication. Moreover, the antioxidant properties of these oils support the bioactive roles of its protective effects on DZN toxicity. This study therefore suggests that these oils could be used as preventive factors against the toxicity of DZN due to its antioxidant properties

    Effect of acidizing rate on enhanced oil recovery for Eocene Thebes limestone, Eastern of the Gulf of Suez, Egypt

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    38-42Thebes Limestone of Eocene age contributes to oil producing reservoir of Abu Rudeis Field. Acidizing process has been applied successfully for many years to increase the productivity of petroleum wells in carbonate formations, consequently demands of application acidizing techniques are increasing. Carbonate acidizing differs than that occurs in sandstone because the reactive nature of a carbonate rock, as a result of this, carbonate acidizing causes formation of large flow channels in some portions of the rock comparing with the original pore size distrubution, in addition enlarging of some aspects as diameters, areas and volumes of original pores. This study investigated that the presence of oil slows reaction rate of HCL acid with a carbonate reservoir rock, where the treatment of carbonate reservoir rock with high concentrated HCL acid speeds up the acidizing rate, decreases the effect of oil within the rock and creates much new channels that facilitate injectivity and productivity of oil wells. The effects of acidizing on carbonate rocks at various conditions were different and obvious, consequently help us to improve the oil recovery from reservoir rocks
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