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Search Results: 1 - 10 of 223906 matches for " Raafat R. Rizkallah "
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Numerical Solution of MHD Boundary Layer Flow of Non-Newtonian Casson Fluid on a Moving Wedge with Heat and Mass Transfer and Induced Magnetic Field  [PDF]
Nabil T. El-Dabe, Ahmed Y. Ghaly, Raafat R. Rizkallah, Karem M. Ewis, Ameen S. Al-Bareda
Journal of Applied Mathematics and Physics (JAMP) , 2015, DOI: 10.4236/jamp.2015.36078
Abstract: The paper investigates the numerical solution of the magnetohydrodynamics (MHD) boundary layer flow of non-Newtonian Casson fluid on a moving wedge with heat and mass transfer. The effects of thermal diffusion and diffusion thermo with induced magnetic field are taken in consideration. The governing partial differential equations are transformed into nonlinear ordinary differential equations by applying the similarity transformation and solved numerically by using finite difference method (FDM). The effects of various governing parameters, on the velocity, temperature and concentration are displayed through graphs and discussed numerically. In order to verify the accuracy of the present results, we have compared these results with the analytical solutions by using the differential transform method (DTM). It is observed that this approximate numerical solution is in good agreement with the analytical solution. Furthermore, comparisons of the present results with previously published work show that the present results have high accuracy.
Role of Internet of Things in the Smart Grid Technology  [PDF]
A. R. Al-Ali, Raafat Aburukba
Journal of Computer and Communications (JCC) , 2015, DOI: 10.4236/jcc.2015.35029

The Internet of Things (IoT) has recently emerged as enabling technology for the smart gird, smart health, smart transportation, and smart environment as well as for smart cities. The major smart grid devices are smart home appliances, distributed renewable energy resources and power substations. The seven domains existing smart grid conceptual model was developed without the IoT concept in mind. As the smart grid evolved, many attempts started to introduce the IoT as enabling technology to the grid. Each device in the grid can be considered as an object. Utilizing the concept of IoT, each device can have a unique IP address that can upload its status and download control commands via the Internet. This paper proposes a conceptual model for the smart grid within the Internet of Things context. The proposed model is based on IPV6 as the backbone of the smart grid communications layer.

Numerical Solution of MHD Flow of Micropolar Fluid with Heat and Mass Transfer towards a Stagnation Point on a Vertical Plate  [PDF]
N. T. El-Dabe, A. Y. Ghaly, R. R. Rizkallah, K. M. Ewis, A. S. Al-Bareda
American Journal of Computational Mathematics (AJCM) , 2015, DOI: 10.4236/ajcm.2015.52013
Abstract: The paper investigates the numerical solution of problem of magnetohydrodynamic (MHD) micropolar fluid flow with heat and mass transfer towards a stagnation point on a vertical plate. In this study, we consider both strong concentrations (n = 0) and weak concentrations (n = 1/2). The governing equations have been transformed into nonlinear ordinary differential equations by applying the similarity transformation and have been solved numerically by using the finite difference method (FDM) and analytically by using (DTM). The effects of various governing parameters, namely, material parameter, radiation parameter, magnetic parameter, Prandtl number, Schmidt number, chemical reaction parameter and Soret number on the velocity, microrotation, temperature and concentration have been computed and discussed in detail through some figures and tables. In order to verify the accuracy of the present results, we have compared these results with the analytical solutions by using the differential transform method (DTM) and the multi-step differential transform method (MDTM). It is observed that this approximate numerical solution is in good agreement with the analytical solution.
Gut Pharmacomicrobiomics: the tip of an iceberg of complex interactions between drugs and gut-associated microbes
Rama Saad, Mariam R Rizkallah, Ramy K Aziz
Gut Pathogens , 2012, DOI: 10.1186/1757-4749-4-16
Abstract: The gut microbiota is the most predominant and most diverse microbial community residing in the human body [1]. It comprises hundreds of microbial species, together constituting about 10 times the number of body cells [2,3], and contributes substantially to human metabolic processes to the extent that up to 36 % of small molecules in human blood are contributed by the gut microbiome [4]. The gut microbiota’s impact on drug response and metabolism has been explored since the mid 20th century (reviewed in [5]); however, past studies have mostly focused on assessing the metabolic activity of gut microbial communities on antibiotics and botanicals [6-9]. Meanwhile, the influence of the host genetic makeup on drug response occupied the center stage of personalized medicine research, specifically in the clinical domain, leading to the rise of pharmacogenomic approaches to personalized therapy, while a pivotal player in xenobiotic metabolism, the microbiota, was mostly being overlooked [10,11].The various metabolic capabilities of the gut microbiota fueled the study of its effects on drug metabolism [11,12]. Several approaches were adopted, including comparisons between metabolic patterns of conventional and germfree mice, biochemical assays of microbial metabolic activities in cultures, and mutagenicity tests [5,6,13]. Population-based approaches, such as investigating the correlation between compositional variations in gut microbiota and response to a particular drug, e.g., digoxin, were followed as well [9].The evolution of microbial genomics from culture-based (i.e., sequencing genomes of bacterial species after isolating their colonies) to culture-independent strategies (metagenomics—or shotgun sequencing of microbial and viral communities [14,15]) has allowed the identification of the molecular signature of the gut microbiome associated with a certain disease or with altered drug response [16]. To describe this new expansion of pharmacogenomics, we suggested the term
Obesity in Lebanon: A National Problem  [PDF]
S. Mallat, A. Gerges Geagea, R. A. Jurjus, A. Rizkallah, D. Oueidat, M. Matar, J. Tawilah, A. Berbari, A. R. Jurjus
World Journal of Cardiovascular Diseases (WJCD) , 2016, DOI: 10.4236/wjcd.2016.66017
Abstract: Obesity is a major health problem, because of its relationship with serious medical illnesses and significant economic consequences. This article explores various factors and variables affecting the prevalence of obesity in Lebanon, to focus public health initiatives and medical interventions in the management of obesity. This study interviewed 593 subjects, of more than 20 years, from all governorates of Lebanon. The interview covered personal and demographic data, awareness, knowledge, attitude and practices towards obesity including diet and physical activity. Males’ and females’ percentages were 51.6% and 48.4%, respectively, and a young population profile was with 52.8% less than 40 years of age. The BMI index showed that 52.77% were obese with 70.6% males and 34.27% females. The great majority were educated. TV was the most used media outlet, 79.61% watching daily between 1 - 4 hours. Obesity was considered as the most important health problem by 27.6% and ranking the 5th after cancer, cardiovascular, smoking and HIV/AIDS. About two thirds considered it a risk factor for hypertension and type 2 diabetes mellitus and 80.27% for cardiovascular diseases. Interventions should include changes in diet habits whereby, approximately one third (33.5%) drink carbonated beverages on a daily basis and 50.76% eat fast food, with a lack of awareness about daily calories intake by 75.38%. About half of the population (56.32%) walks daily for 20 minutes. Most people favored behavioral and lifestyle modifications in management rather than medications and surgery (67.79%). This study provides baseline data regarding several aspects of an obesogenic environment, a major risk factor for several diseases including hypertension, diabetes and other non-communicable diseases. After describing the factors and variables affecting the prevalence of obesity, some suggestions for appropriate interventions are included, with the hope of reducing the health burden of obesity in Lebanon.
On The Cohomology of $\mathrm{SL}_2$ with Coefficients in a Simple Module
John Rizkallah
Mathematics , 2014,
Abstract: Let $G$ be the simple algebraic group $\mathrm{SL}_2$ defined over an algebraically closed field $k$ of characteristic $p > 0$. Using results of A. Parker, we develop a method which gives, for any $q \in \mathbb{N}$, a closed form description of all simple modules $M$ such that $\mathrm{H}^q(G,M) \neq 0$, together with the associated dimensions $\mathrm{dim}\mathrm{H}^q(G,M)$. We apply this method for arbitrary primes $p$ and for $q \leq 3$, confirming results of Cline and Stewart along the way. Furthermore, we show that under the hypothesis $p > q$, the dimension of the cohomology $\mathrm{H}^q(G,M)$ is at most 1, for any simple module $M$. Based on this evidence we discuss a conjecture for general semisimple algebraic groups.
Anisotropic Left-Handed and -Negative Slab Waveguides: Physics and Device Applications
Hamidreza Salehi,Sujeet K. Chaudhuri,Raafat R. Mansour
Advances in OptoElectronics , 2007, DOI: 10.1155/2007/46861
Abstract: We study the properties of various anisotropic left-handed slab waveguides. The analysis is extended to anisotropic μ-negative slab waveguides. The possible existence of the plasmon modes in various anisotropic slab waveguide configurations is discussed. An FDTD program is developed to investigate the potential device applications of these anisotropic structures. A new signal detector and a two-channel harmonic separator multiplexer are designed employing the μ-negative slab waveguide.
Characteristics of Iranian Women with Breast Cancer
Jahangir Raafat
Research Journal of Biological Sciences , 2012,
Abstract: Breast cancer is the most common malignancy in adult female population. Great variations exist in incidence and mortality rate of this cancer in different populations. One of the most important and central factors that can greatly affect mortality of a cancer in a population is the stage of cancer which comes under medical attention. In this cross-sectional study, we describe characteristics of 1500 cases of breast cancer at the time of diagnosis and evaluate probable association between some factors and stage of cancer in which cancer comes under medical attention. This retrospective cross-sectional study reviewed files of 1500 cases of female breast cancer. These cases had been referred to a breast cancer private clinic and diagnosis of breast cancer was confirmed by pathologic study. Data about following factors were extracted from files: age of patients, educational level, profession, interval between seeking medical attention and diagnosis confirmation, family history of breast cancer in first-degree relatives, method of diagnosis, results of mammography, tumor size, number of involved lymph nodes, total number of resected lymph nodes and pathologic stage of tumor. All data of been obtained at the time of diagnosis. Mean age of patients was 49.38±10.46 years. From patients with known size of tumor, 74.5% had a size of >2 cm in the population and in patients with known stage of disease, 78.3% of patients were stage 2 or more which means that they had at least one involved lymph node. On an average, an interval of 2.73±1.15 years existed between the time of suspicion and time of definite diagnosis. Finally we conclude that stage of breast cancer at presentation is higher in our country when compared with western countries. This difference is both the result of lower compliance of patients and defects in public services.
Robust H Controller for High Precision Positioning System, Design, Analysis, and Implementation  [PDF]
Safanah M. Raafat, Rini Akmeliawati, Ismael Abdulljabaar
Intelligent Control and Automation (ICA) , 2012, DOI: 10.4236/ica.2012.33030
Abstract: In this paper, a systematic robust control design and analysis for a single axis precise positioner is presented. The effects of uncertainties on closed-loop stability and performance are considered in the H∞ robust controllers design. v-gap metric is utilized to validate the intelligently estimated uncertainty. The robust controllers are formulated within the frame- work of the standard H mixed sensitivity optimization problem. Furthermore, a specially designed integral-H∞ and two-degree-of-freedom 2 DOF H controllers are developed to provide improved robust performance and resolution properties. It is shown that the proposed design schemes are very effective for robust control and precise tracking performance of the servo positioning system.
Integrative Approach to Quality Assessment of Medical Journals Using Impact Factor, Eigenfactor, and Article Influence Scores
Jacques Rizkallah,Don D. Sin
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010204
Abstract: Impact factor (IF) is a commonly used surrogate for assessing the scientific quality of journals and articles. There is growing discontent in the medical community with the use of this quality assessment tool because of its many inherent limitations. To help address such concerns, Eigenfactor (ES) and Article Influence scores (AIS) have been devised to assess scientific impact of journals. The principal aim was to compare the temporal trends in IF, ES, and AIS on the rank order of leading medical journals over time.
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