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Search Results: 1 - 10 of 24764 matches for " Mohamed Ibrahim El-sayed "
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Utilization of Trimethylolpropane Based Hyperbranched Poly(Amine-Ester) as New Polymeric Admixture  [PDF]
Amal Amin Ibrahim, Ahmed El-Sayed Abdel-Magied, Mohamed Sayed Selim, Magdy Mohamed Hussein Ayoub
Open Journal of Organic Polymer Materials (OJOPM) , 2012, DOI: 10.4236/ojopm.2012.22004
Abstract: Hyperbranched poly(amine-ester) (HBPAE) was synthesized via pseudo-one-step process between trimethylolpropane as a core molecule and N, N-diethylol-3-amine methylpropionate as the AB2 branched monomer. The prepared polymer was analyzed by IR, GPC, 1H-NMR and thermal analysis (TGA and DSC). The performance of the polymer in cement was tested by measuring the effect of 1, 3 and 5 wt% of HBPAE solutions on the properties of Ordinary Portland Cement. Water of consistency, setting times, bulk density, apparent porosity, compressive strength and combined water content of the polymer/cement pastes were studied. The results showed that water of consistency and apparent porosity decreased while setting times, compressive strength, combined water and bulk density increased with the polymer addition.
Estimations of Weibull-Geometric Distribution under Progressive Type II Censoring Samples  [PDF]
Azhari A. Elhag, Omar I. O. Ibrahim, Mohamed A. El-Sayed, Gamal A. Abd-Elmougod
Open Journal of Statistics (OJS) , 2015, DOI: 10.4236/ojs.2015.57072

This paper deals with the Bayesian inferences of unknown parameters of the progressively Type II censored Weibull-geometric (WG) distribution. The Bayes estimators cannot be obtained in explicit forms of the unknown parameters under a squared error loss function. The approximate Bayes estimators will be computed using the idea of Markov Chain Monte Carlo (MCMC) method to generate from the posterior distributions. Also the point estimation and confidence intervals based on maximum likelihood and bootstrap technique are also proposed. The approximate Bayes estimators will be obtained under the assumptions of informative and non-informative priors are compared with the maximum likelihood estimators. A numerical example is provided to illustrate the proposed estimation methods here. Maximum likelihood, bootstrap and the different Bayes estimates are compared via a Monte Carlo Simulation study

The Products of Regularly Solvable Operators with Their Spectra in Direct Sum Spaces  [PDF]
Sobhy El-Sayed Ibrahim
Advances in Pure Mathematics (APM) , 2013, DOI: 10.4236/apm.2013.34060

In this paper, we consider the general quasi-differential expressions \"\" each of order n with complex coefficients and their formal adjoints on the interval (a,b). It is shown in direct sum spaces \"\" of functions defined on each of the separate intervals with the cases of one and two singular end-points and when all solutions of the equation \"\" and its adjoint \"\" are in \"\" (the limit circle case) that all well-posed extensions of the minimal operator \"\" have resolvents which are HilbertSchmidt integral operators and consequently have a wholly discrete spectrum. This implies that all the regularly solvable operators have all the standard essential spectra to be empty. These results extend those of formally symmetric expression \"\" studied in [1-10] and those of general quasi-differential expressions

Preoperative Versus Postoperative Radiation Therapy in Patients with Soft Tissue Sarcomas
Mohamed Ibrahim El-sayed,Doaa Wadie Maximos,Mostafa El-sayed Abdel-wanis,Amen Hamdy Zaky
Cancer and Clinical Oncology , 2012, DOI: 10.5539/cco.v1n2p36
Abstract: Purpose: To evaluate treatment outcome and to determine whether or not the timing of radiotherapy (RT) was associated with any difference in disease relapse, survival, or incidence of complications in patients with soft tissue sarcomas (STS). Methods: The medical files of 63 patients with a primary, nonmetastatic, STS, treated with surgery and irradiation were evaluated. Data regarding tumor stage, grade, site, dosage and timing of radiotherapy, treatment complications, disease relapse, and disease-free (DFS) and overall survival (OAS) rates were analyzed. Results: The median follow up was 47 months (range; 5-66 months). Four-year OAS and DFS rates were 82.6% and 78.8% respectively. There were significant higher 4-year OAS (p = 0.024) and DFS (p = 0.011) rates in patients with stage I and II diseases than those in patients with stage III disease. On the other hand, there were no significant differences in 4-year OAS (p = 0.83, HR: 0.743, 95% CI: 0.165 to 3.345) and DFS (p = 0.64, HR: 0.74, 95% CI: 0.21 to 2.61) rates between preoperative and postoperative RT patients. Disease relapse for preoperative versus postoperative RT patients was not statistically different (p = 0.41). Wound complications were more frequent in preoperative RT patients (25%) compared to postoperative RT patients (8%) (p = 0.0566 chi-square). Conclusions: Preoperative irradiation has not a positive impact on survival or disease relapse rates, but is associated with high wound complication rate.
Evaluation of Multiplex Nested Polymerase Chain Reaction for Routine Hepatitis C Virus Genotyping in Egyptian Patients
Mohamed Abbas Shemis,Dina Mohamed El-Abd,Dalia Ibrahim Ramadan,Mohamed Ibrahim El-Sayed
Hepatitis Monthly , 2012,
Abstract: Background: At least six HCV (hepatitis C virus) genotypes are unequally distributed worldwide. HCV genotyping guides the selection of treatment regimens and provides important epidemiological markers that enable the outbreak source to be traced and the spread of disease to be controlled. In Egypt, there is an increasing need for cost-effective, fast, and easily performable HCV genotyping assays.Recently, a multiplex PCR assay was developed to determine HCV genotypes. It employs genotype-specific primers, based on sequences of the entire core region and part of the 5’UTR of the genome.Objectives: In this study, we compared a simple, new, modified multiplex PCR system for HCV genotyping with a commercially available line probe assay (INNO-LiPA) that is based on reverse hybridization.Patients and Methods: Serum samples from chronic HCV Egyptian patients (n = 73) were genotyped using the modified multiplex PCR assay, and genotypes were verified using the INNO-LiPA HCV II assay.Results: The modified multiplex PCR method was able to type HCV-4 in 65 of 70 typeable samples (92.86%) and had 100% concordance with the INNO-LiPA assay.Conclusions: Genotype 4 was the most prevalent genotype in our study. Based on our results, the modified multiplex nested PCR assay is a sensitive and inexpensive alternative for HCV genotyping and can be used in routine diagnostic laboratories. INNO-LiPA may be useful as a second-line assay for genotyping samples that are indeterminate by multiplex PCR. This approach will effect better treatment optimization and a reduction of the spread of HCV.
A New Approach for Dispersion Parameters  [PDF]
Ahmed Mohamed Mohamed El-Sayed
Journal of Applied Mathematics and Physics (JAMP) , 2016, DOI: 10.4236/jamp.2016.48165
Abstract: This paper presents a new approach to identify and estimate the dispersion parameters for bivariate, trivariate and multivariate correlated binary data, not only with scalar value but also with matrix values. For this direction, we present some recent studies indicating the impact of over-dispersion on the univariate data analysis and comparing a new approach with these studies. Following the property of McCullagh and Nelder [1] for identifying dispersion parameter in univariate case, we extended this property to analyze the correlated binary data in higher cases. Finally, we used these estimates to modify the correlated binary data, to decrease its over-dispersion, using the Hunua Ranges data as an ecology problem.
Study of Similarity Measures with Linear Discriminant Analysis for Face Recognition  [PDF]
Mohamed A. El-Sayed, Kadry Hamed
Journal of Software Engineering and Applications (JSEA) , 2015, DOI: 10.4236/jsea.2015.89046
Abstract: Face recognition systems have been in the active research in the area of image processing for quite a long time. Evaluating the face recognition system was carried out with various types of algorithms used for extracting the features, their classification and matching. Similarity measure or distance measure is also an important factor in assessing the quality of a face recognition system. There are various distance measures in literature which are widely used in this area. In this work, a new class of similarity measure based on the Lp metric between fuzzy sets is proposed which gives better results when compared to the existing distance measures in the area with Linear Discriminant Analysis (LDA). The result points to a positive direction that with the existing feature extraction methods itself the results can be improved if the similarity measure in the matching part is efficient.
Effect of Atrial Fibrillation on Acute Ischemic Stroke Severity  [PDF]
Taha Kamel Alloush, Mahmoud Haroun Ibrahim, Nahed Salah El Dein Ahmed Ibrahim, Ghada Samir El-Shahed, Lobna Mohamed Nabil El-Sayed, Mohamed Hamdy Ibrahim, Hosam Ahmed Azmy
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.42013
Objectives: To assess the impact of atrial fibrillation on stroke severity and short-term (1 month) mortality. Materials and Methods: Totally 200 patients admitted to Ain Shams University Specialized Hospital were recruited and diagnosed clinically to have acute ischemic stroke within 3 days. Patients with hemorrhagic infarctions were excluded. History taking about previous heart disease was taken, full general and neurological examinations were done. Full metabolic profile, full cardiac investigations, carotid duplex, MRI brain stroke protocol with initial clinical evaluation and after 1 month re-evaluation using (NIHSS ) scale. Results: All patients underwent transthoracic echocardiography which revealed absence of “A” wave corresponding to atrial fibrillation in 33 patients (16.5%). Those Patients with atrial fibrillation had a median NIHSS score of 11.00 with IQR of 6.00 - 18.50 at admission and 6.00 with IQR of 2.00 - 14.50 after one month. Patients with atrial fibrillation showed significantly higher NIHSS at admission than patients in sinus rhythm, P < 0.05. Magnetic resonance imaging findings showed that MRA showed significant intracranial vessel stenosis in 117 (79.1%) patients. 51 (34.4%) patients had lacunar infarction, 65 (43.9%) patients had partial anterior circulation infarction, 25 (16.2%) patients had posterior circulation infarction and 7 (4.7%) patients had total anterior circulation infarction. 111 (75%) patients showed leucoaraiosis. Conclusion: Atrial fibrillation was found not to have significantly statistical effect on stroke severity and short term mortality.
Effect of Heart Failure on Acute Ischemic Stroke Severity  [PDF]
Taha Kamel Alloush, Mahmoud Haroun Ibrahim, Nahed Salah El-Dein Ahmed, Ghada Samir El-Shahed, Lobna M. El-Nabil El-Sayed, Mohamed Hamdy Ibrahim, Hosam Ahmed Azmy
Open Journal of Medical Imaging (OJMI) , 2014, DOI: 10.4236/ojmi.2014.43014
Objectives: To assess the impact of heart failure diseases on stroke severity and short term (1 month mortality). Materials and Methods: Totally, 200 patients admitted to Ain Shams university specialized hospital, were diagnosed clinically to have acute ischemic stroke within 3 days. History taking about previous heart disease was taken, and full general and neurological examinations were done. Full metabolic profile, cardiac examination and investigations were done. Carotid duplex, MRI stroke protocol and lastly clinical reevaluation using NIH Stroke Scale (NIHSS) after 1 month from stroke onset were done. Results: Patients with systolic dysfunction (EF ≤ 40%) had lacunar infarction in 18.75% of cases, partial anterior circulation infarction in 62.5% of cases, posterior circulation infarction in 6.25% of cases and total anterior circulation infarction in 12.5% of cases. Leucoaraiosis was present in 87% of cases and significant intracranial vessel stenosis was showed in 87.5% who had done MRI. Their median NIHSS score at admission was 10.5 with IQR of 5 - 21 and at follow-up it was 5 with IQR of 2.5 - 10.5. At follow-up 22.7% (5 patients) were dead. Conclusion: Systolic dysfunction (EF < 40) i.e. heart failure has no significant effect on stroke severity and 1 month follow up prognosis.
Experimental Study of Heat Transfer to Flowing Air inside a Circular Tube with Longitudinal Continuous and Interrupted Fins  [PDF]
Saad A. El-Sayed, Sayed A. EL-Sayed, Mohamed M. Saadoun
Journal of Electronics Cooling and Thermal Control (JECTC) , 2012, DOI: 10.4236/jectc.2012.21001
Abstract: Experimental investigations have been performed to determine the detailed module-by-module pressure drop and heat transfer coefficient of turbulent flow inside a circular finned tube. The tubes are provided with longitudinal fins continuous or interrupted in the stream wise direction by arranging them both in a staggered and in-line manner. Experiments are carried out for two different fin geometries, with two numbers of fins (N = 6 and 12). All tested finned tubes have 16 modules each with length equal to the tube diameter (L = D = 30 mm). The thermal boundary condition considered here, is a uniform heat flux. The module-by-module heat transfer coefficient is found to vary only in the first modules, and then attained a constant thermally periodic fully developed value after eight to twelve modules. The results also showed that in the periodic hydrodynamic fully developed region, the value of the pressure drop along the tube with continuous fins is greater than that of the in-line arrangement, and lower than that of the staggered arrangement. Furthermore, the results showed that in the periodic fully developed region, the tube with continuous fins produces a greater value of the heat transfer coefficients than that the tube with interrupted fins, especially through a high range of Reynolds number (5 × 104 > Re > 2 × 104). The tube with Staggered arrangement of fins produces a greater value of the heat transfer coefficient than the tube with continuous fins and the in-line arrangement finned tube at low Reynolds number (Re < 1.2 × 104).). It was found that the fins efficiency is greater than 90 percent; in the worst case (maximum Reynolds number with continuous fins tube).
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