检索结果-南通市图书馆

Five-dimensional teleparallel theory equivalent to general relativity,the axially symmetric solution,energy and spatial momentum

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2011年第11期20卷 102-109页

作者： gamal G.L.Nashed mathematics Department Faculty of ScienceAin Shams University

A theory of （4＋1）-dimensional gravity is developed on the basis of the teleparallel theory equivalent to general relativity. The fundamental gravitational field variables are the five-dimensional vector fields （pentad）, defined globally on a manifold m, and gravity is attributed to the torsion. The Lagrangian density is quadratic in the torsion tensor. We then give the exact five-dimensional solution. The solution is a generalization of the familiar Schwarzschild and Kerr solutions of the four-dimensional teleparallel equivalent of general relativity. We also use the definition of the gravitational energy to calculate the energy and the spatial momentum.

关键词： five-dimensional teleparallel equivalent of general relativity five-dimensional solution energy and spatial momentum

Teleparallel equivalent theory of (1+1)-dimensional gravity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2010年第11期19卷 124-131页

作者： gamal G.L.Nashed mathematics Department Faculty of ScienceAin Shams UniversityCairoEgypt Centre for Theoretical Physics The Bvitish University in EgyptEl-Sherouk CityMisr-Ismalia Desert RoadPostal No.11837P.O.Box 43Egypt

A theory of （1＋1）-dimensional gravity is constructed on the basis of the teleparallel equivalent of general relativity. The fundamental field variables are the tetrad fields ei^μ and the gravity is attributed to the torsion. A dilatonic spherically symmetric exact solution of the gravitational field equations characterized by two parameters m and Q is derived. The energy associated with this solution is calculated using the two-dimensional gravitational energy- momentum formula.

关键词： teleparallel equivalent theory of (1+1)-dimensional gravity two-dimensional spherically symmetric dilatonic black hole energy

Cosmological application on five-dimensional teleparallel theory equivalent to general relativity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第10期21卷 122-129页

作者： gamal G.L.Nashed mathematics Department Faculty of ScienceKing Faisal UniversityP.O.Box 380 Al-Ahsaa 31982the Kingdom of Saudi Arabia mathematics Department Faculty of ScienceAin Shams UniversityCairo 11566Egypt Center for Theoretical Physics British University of EgyptSherouk City 11837P.O.Box 43Egypt

A theory of（4＋1）-dimensional gravity has been developed on the basis of which equivalent to the theory of general relativity by *** fundamental gravitational field variables are the 5-dimensional（5D） vector fields（pentad）,defined globally on a manifold m,and gravity is attributed to the *** Lagrangian density is quadratic in the torsion *** then apply the field equations to two different homogenous and isotropic geometric structures which give the same line element,i.e.,FRW in five *** cosmological parameters are calculated and some cosmological problems are discussed.

关键词： 5D teleparallel equivalent of general relativity 5D solutions cosmological parameters cosmological problems

Gravitational collapse with standard and dark energy in the teleparallel equivalent of general relativity

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2012年第6期21卷 57-62页

作者： gamal G.L.Nashed mathematics Department Faculty of ScienceKing Faisal UniversityP.O.Box 380 Al-Ahsaa 31982the Kingdom of Saudi Arabia mathematics Department Faculty of ScienceAin Shams UniversityCairo11566Egypt Center for Theoretical Physics British University of EgyptSherouk City 11837P.O.Box 43Egypt

A perfect fluid with self-similarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity （TEGR）. A spacetime which is not asymptotically fiat is derived. The energy conditions of this spacetime are studied. It is shown that after some time the strong energy condition is not enough to satisfy showing a transition from standard matter to dark energy. The singularities of this solution are discussed.

关键词： perfect fluid with self-similarity of second kind teleparallel equivalent of general relativ-ity asymptotically nonflat spacetime energy conditions

Climate change impact and adaptation on wheat yield, water use and water use efficiency at North Nile Delta

在线全文

学校读者我要写书评

暂无评论

Frontiers of Earth Science 2020年第3期14卷 522-536页

作者： marwa gamal mohamed Ali mahmoud mohamed ibrahim Ahmed El Baroudy michael Fullen El-Said Hamad Omar Zheli Ding Ahmed mohammed Saad Kheir Soil and Water Department Faculty of AgricultureTanta UniversityTanta33516Egypt Soils Water and Environment Research InstituteAgricultural Research CenterGiza12411Egypt Faculty of Science and Engineering The University of WolverhamptonWolverhamptonWV11LYUK Haikou Experimental Station Chinese Academy of Tropical Agricultural Sciences(CATAS)Haikou570000China

Investigation of climate change impacts on food security has become a global hot *** so,efforts to mitigate these issues in arid regions have been ***,in this paper,further research is discussed based on data obtained from various crop and climate *** DSSATcrop models(Cms)(CERESWheat and N-Wheat)were calibrated with two wheat cultivars(Gemiza9 and misr1).A baseline simulation(1981-2010)was compared with different scenarios of simulations using three Global Climate models(GCms)for the 2030s,2050s and *** impacts of climate change were assessed using the GCms and Cms under the high emission Representative Concentration Pathway(RCP8.5).Results predicted decreased wheat grain yields by a mean of 8.7%,11.4%and 13.2%in the 2030s,2050s and 2080s,respectively,relative to the baseline *** impacts of climatic change are probable,despite some uncertainties within the GCms(i.e.,2.1%,5.0%and 8.0%)and Cms(i.e.,2.2%,6.0%and 9.2%).Changing the planting date with a scenario of plus or minus 5 or 10 days from the common practice was assessed as a potentially effective adaptation option,which may partially offset the negative impacts of climate *** the sowing date by 10 days(from 20 November to 30 November)proved the optimum scenario and decreased further reduction in wheat yields resulting from climate change to 5.2%,6.8%and 8.5%in the 2030s,2050s and 2080s,respectively,compared with the 20 November *** planting 5-days earlier scenario showed a decreased impact on climate change ***,the 10-days early planting scenario increased yield reduction under projected climate *** cultivar misr1 was more resistant to rising temperature than *** the negative impacts of projected climate change on wheat production,water use efficiency would slightly *** ensemble of multi-model estimated impacts and adaptation uncertainties of climate change can assist decision-makers in planning clima

关键词： DSSAT models scenarios adaptation water use efficiency climate change

Cryopreservation of cattle semen using coconut water extender with different glycerol concentrations

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian pacific Journal of Reproduction 2017年第6期6卷 279-282页

作者： Reda ibrahim El-Sheshtawy Walid Said El-Nattat gamal Abdel Daiem Ali Animal Reproduction and Al Department Veterinary DivisionNational Research CentreDokkiGizaEgypt

Objective:To investigate the effect of coconut water with a lone concentration and different concentrations of glycerol on chilled and cryopreserved cattle semen ***: Semen was collected from five mature cattle bulls, at weekly intervals for 5 weeks. The ejaculates were pooled and evaluated for dilution processing. Tris citrate egg yolk fructose was used as control treatment for semen, while 50% (V/V) coconut water, 25% (V/V) bi-distilled water and 25% (V/V, 5% anhydrous monosodium citrate) to 20 mL egg yolk and three different concentrations of glycerol (4%, 6% and 8%) were used as coconut water (CW)-glycerol-yolk extenders (CWCG-4, CWCG-6 and CWCG-8). Extended semen was cooled and cryopreserved. Sperm motility%, sperm membrane integrity%, normal acrosome%, live sperm% and total sperm abnormalities% were recorded after equilibrium and after ***:The addition of 4% glycerol to coconut water enriched media (CWCG-4) revealed the most effective addition of glycerol on all parameters after equilibrium and after ***:Coconut water enriched media with 4% glycerol addition is safe to be used as an extender in bull semen preservation because it is a sterile liquid. So, it can be used without addition of antibiotics to the extender, as antibiotics have to some extent hazardous effect on spermatozoa.

关键词： Semen Glycerol Coconut water Freeze thawing

Ensemble machine Learning to Enhance Q8 Protein Secondary Structure Prediction

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Computers, materials & Continua 2022年第11期73卷 3951-3967页

作者： moheb R.Girgis Rofida m.gamal Enas Elgeldawi Computer Science Department Faculty of ScienceMinia University61519MiniaEgypt

Protein structure prediction is one of the most essential objectives practiced by theoretical chemistry and bioinformatics as it is of a vital importance in medicine,biotechnology and *** secondary structure prediction(PSSP)has a significant role in the prediction of protein tertiary structure,as it bridges the gap between the protein primary sequences and tertiary structure *** secondary structures are classified into two categories:3-state category and 8-state *** the 3 states and the 8 states of secondary structures from protein sequences are called the Q3 prediction and the Q8 prediction problems,*** 8 classes of secondary structures reveal more precise structural information for a variety of applications than the 3 classes of secondary structures,however,Q8 prediction has been found to be very challenging,that is why all previous work done in PSSP have focused on Q3 *** this paper,we develop an ensemble machine Learning(mL)approach for Q8 PSSP to explore the performance of ensemble learning algorithms compared to that of individual mL algorithms in Q8 *** ensemble members considered for constructing the ensemble models are well known classifiers,namely SVm(Support Vector machines),KNN(K-Nearest Neighbor),DT(Decision Tree),RF(Random Forest),and NB(Naïve Bayes),with two feature extraction techniques,namely LDA(Linear Discriminate Analysis)and PCA(Principal Component Analysis).Experiments have been conducted for evaluating the performance of single models and ensemble models,with PCA and LDA,in Q8 *** novelty of this paper lies in the introduction of ensemble learning in Q8 PSSP *** experimental results confirmed that ensemble mL models are more accurate than individual mL *** also indicated that features extracted by LDA are more effective than those extracted by PCA.

关键词： Protein secondary structure prediction(PSSP) Q3 prediction Q8 prediction ensemble machine leaning boosting bagging

Ameliorative effect of morus alba leaves extract against developmental retinopathy in pups of diabetic and aluminum intoxicated pregnant albino rats

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Asian Pacific Journal of Tropical Biomedicine 2015年第4期5卷 300-309页

作者： Hassan El-Sayyed gamal Badawy Sobhy Hassab Elnabi ibrahim El-Elaimy Eman Al Shehari Department of Zoology Faculty of Science Mansoura University Department of Zoology Faculty of Science Menoufiya University

Objective: To investigate the possible ameliorative effect of crude water extract of morus alba(m. alba) leaves on retinopathy of rat pups maternally subjected to diabetes and/or Al ***: Both control and experimental groups were subjected to certain integrated approaches, namely, biochemical assessments, light microscopic investigation, transmission electron microscopic investigation, single cell gel electrophoresis(comet assay) and determination of DNA ***: The retina of pups of diabetic and/or Al-intoxicated mothers exhibited abnormal alterations in retinal cell layers including retinal pigmented epithelium, photoreceptor inner segment and ganglion cells. Increased incidence of DNA fragmentation and apoptosis were evident in pups of diabetic and/or Al-intoxicated mothers. However, retina of pups maternally received m. alba extract plus diabetes or Al-intoxicated alone or in combination showed marked amelioration. Less degree of ameliorations was seen in retina of pups maternally subjected to combined treatment. Furthermore, application of crude water extract of *** resulted in amelioration of the alterations of maternal serum glucose as well as Al ***: Based on the results of the present study, m. alba extract is effective against experimentally diabetic and Al-induced developmental retinopathy.

关键词： morus alba Retinopathy Aluminum Diabetes TEm Comet assay

Regular Charged Solutions in mφller＇s Tetrad Theory of Gravitation

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 2007年第11期24卷 3059-3062页

作者： gamal G. L. Nashed Department of mathematics Faculty of Science Ain Shams University Cairo Egypt

We find the most general tetrads which give a regular charged spacetime in tetrad theory of gravitation. The metric is a static one and it includes the Schwarzschild and Fteissner Nordstrom black holes. The energy content contained in a sphere of radius R is calculated using the superpotential given by mφller in the context of Weitzenbock spacetime.

关键词： Regular Charged Solutions Tetrad Gravitation