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Management of complicated gallstones in the elderly:comparing surgical and non-surgical treatment options

Gastroenterology Report 2019年第3期7卷 205-211,I0002页

作者： yousef nassar Seth Richter Department of Medicine Albany Medical Center43 New Scotland AvenueAlbanyNY 12208USA Division of Gastroenterology Albany Medical Center43 New Scotland AvenueAlbanyNY 12208USA

Objective:The aim of this study was to evaluate the differences in clinical outcomes of endoscopic retrograde cholangiopancreatography(ERCP),ERCP followed by cholecystectomy(EC)and percutaneous aspiration(PA)in the elderly population with ***:We included a total of 43338 elderly patients aged 60 years or older and 45295 patients younger than 60 years for comparison in our *** were obtained from the Nationwide Inpatient Sample(Healthcare Utilization Project)for years 2001–14 by identifying patients who were admitted for gallstone complications based on the ICD 9 diagnostic *** logistic regression was used to calculate the odds of in-hospital mortality and to detect statistical differences among the treatment groups,age groups and between male and female *** ordinary linear regression was used to compare the length of hospital stay and readmission frequency among the different age ***:The age of the patient affected mortality and the length of hospital stay after any type of procedure of gallstones *** a manner independent of the patient’s age,PA was associated with the highest risk of death and length of stay,while the EC was characterized by lowest mortality and ERCP by the shortest length of *** age of the patient nor the type of procedure affected the likelihood of *** odds of death and the probability of readmission were not affected by patient ***,in patients aged between 60 and 79 years,the female gender predicted a shorter duration of stay in the ***:A patient’s age negatively affects the treatment outcomes of cholelithiasis with associated *** EC procedure appears to be the method of choice for the management of complicated gallstones in patients of all ages.

关键词： Gallstone disease elderly cholecystectomy endoscopic retrograde cholangiopancreatography percutaneous aspiration

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AN UNCONDITIONALLY STABLE HYBRID FE-FD SCHEME FOR SOLVING A 3-D HEAT TRANSPORT EQUATION IN A CYLINDRICAL THIN FILM WITH SUB-MICROSCALE THICKNESS

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Journal of Computational Mathematics 2003年第5期21卷 555-568页

作者： Raja nassar Mathematics and Statistics College of Engineering and Science Louisiana Tech University Ruston LA 71272 USA

Heat transport at the microscale is of vital importance in microtechnology applications. The heat transport equation is different from the traditional heat transport equation since a second order derivative of temperature with respect to time and a third-order mixed derivative of temperature with respect to space and time are introduced. In this study, we develop a hybrid finite element-finite difference (FE-FD) scheme with two levels in time for the three dimensional heat transport equation in a cylindrical thin film with sub-microscale thickness. It is shown that the scheme is unconditionally stable. The scheme is then employed to obtain the temperature rise in a sub-microscale cylindrical gold film. The method can be applied to obtain the temperature rise in any thin films with sub-microscale thickness, where the geometry in the planar direction is arbitrary.

关键词： Finite element Finite difference Stability Heat transport equation Thin film Microscale

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MODELING OF FREE JUMPS DOWNSTREAM SYMMETRIC AND ASYMMETRIC EXPANSIONS:THEORITICAL ANALYSIS AND METHOD OF STOCHASTIC GRADIENT BOOSTING

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Journal of Hydrodynamics 2010年第1期22卷 110-120页

作者： MOHAMED A.nassar Water and Water Structures Engineering Department Faculty of EngineeringZagazig University

The general computational approach of Stochastic Gradient Boosting （SGB） is seen as one of the most powerful methods in predictive data mining. Its applications include regression analysis, classification problems with/without continuous categorical predictors. The present theoretical and experimental study aims to model the free hydraulic jump created through rectangular Channels Downstream （DS） symmetric and asymmetric expansions using SGB. A theoretical model for prediction of the depth ratio of jumps is developed using the governing flow equations. At the same time, statistical models using linear regression are also developed. Three different parameters of the hydraulic jump are investigated experimentally using modified angled-guide walls. The results from the modified SGB model indicate a significant improvement on the original models. The present study shows the possibility of applying the modified SGB method in engineering designs and other practical applications.

关键词： Stochastic Gradient Boosting (SGB) free jump symmetric asymmetric theoretical regression experiment

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On a New Version of Weibull Model:Statistical Properties,Parameter Estimation and Applications

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Computer Modeling in Engineering & Sciences 2023年第12期137卷 2219-2241页

作者： Hassan Okasha Mazen nassar Department of Statistics Faculty of ScienceKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Mathematics Faculty of ScienceAl-Azhar UniversityNasr CityCairo11884Egypt Department of Statistics Faculty of CommerceZagazig UniversityZagazig44519Egypt

In this paper,we introduce a new four-parameter version of the traditional Weibull *** is able to provide seven shapes of hazard rate,including constant,decreasing,increasing,unimodal,bathtub,unimodal then bathtub,and bathtub then unimodal *** basic characteristics of the proposedmodel are studied,including moments,entropies,mean deviations and order statistics,and its parameters are estimated using the maximum likelihood *** on the asymptotic properties of the estimators,the approximate confidence intervals are also taken into consideration in addition to the point *** examine the effectiveness of the maximum likelihood estimators of the model’s parameters through simulation *** on the simulation findings,it can be concluded that the provided estimators are consistent and that asymptotic normality is a good method to get the interval *** actual data sets for COVID-19,engineering and blood cancer are used to empirically demonstrate the new distribution’s usefulness inmodeling real-world *** analysis demonstrates the proposed distribution’s ability in modeling many forms of data as opposed to some of its well-known sub-models,such as alpha powerWeibull distribution.

关键词： Weibull distribution alpha power transformation method maximum likelihood entropy order statistics

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Computational Analysis of Novel Extended Lindley Progressively Censored Data

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Computer Modeling in Engineering & Sciences 2024年第3期138卷 2571-2596页

作者： Refah Alotaibi Mazen nassar Ahmed Elshahhat Department of Mathematical Sciences College of SciencePrincess Nourah bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia Department of Statistics Faculty of ScienceKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Statistics Faculty of CommerceZagazig UniversityZagazigEgypt Faculty of Technology and Development Zagazig UniversityZagazig44519Egypt

A novel extended Lindley lifetime model that exhibits unimodal or decreasing density shapes as well as increasing,bathtub or unimodal-then-bathtub failure rates, named the Marshall-Olkin-Lindley (MOL) model is *** this research, using a progressive Type-II censored, various inferences of the MOL model parameters oflife are introduced. Utilizing the maximum likelihood method as a classical approach, the estimators of themodel parameters and various reliability measures are investigated. Against both symmetric and asymmetric lossfunctions, the Bayesian estimates are obtained using the Markov Chain Monte Carlo (MCMC) technique with theassumption of independent gamma priors. From the Fisher information data and the simulatedMarkovian chains,the approximate asymptotic interval and the highest posterior density interval, respectively, of each unknownparameter are calculated. Via an extensive simulated study, the usefulness of the various suggested strategies isassessedwith respect to some evaluationmetrics such as mean squared errors, mean relative absolute biases, averageconfidence lengths, and coverage percentages. Comparing the Bayesian estimations based on the asymmetric lossfunction to the traditional technique or the symmetric loss function-based Bayesian estimations, the analysisdemonstrates that asymmetric loss function-based Bayesian estimations are preferred. Finally, two data sets,representing vinyl chloride and repairable mechanical equipment items, have been investigated to support theapproaches proposed and show the superiority of the proposed model compared to the other fourteen lifetimemodels.

关键词： Marshall-Olkin-Lindleymodel reliability inference Bayesian and classical inference progressive Type-II censoring

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Screening for retinopathy of prematurity:a report from upper Egypt

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International Journal of Ophthalmology(English edition) 2016年第2期9卷 262-265页

作者： Mahmoud M.nassar Department of Ophthalmology Minia University Hospital

AIM： To detect the incidence of retinopathy of prematurity （ROP） in a tertiary referral neonatal intensive care unit in upper Egypt and to describe the obstacles faced during implementing the screening protocol for the first time. METHODS： Consecutive infants were enrolled at birth and screened for ROP. We used the UK ROP guideline （May 2008） for infant selection, follow up and treatment. Repeat examinations were performed until retinal vascularisation was complete. RESULTS： Fifty-two infants were enrolled： 24 males and 28 females. Mean gestational age was 31.3wk （±2.8 SD） and mean birth weight was 1234,6 g （±221.1 SD）. Incidence of ROP was 36.5% （stages 1, 2, 3 and 4a were 9.6%, 9.6%, 15.4% and 1.9% respectively）, no stages 4b or 5 were found in this series. Six infants （11.5%） died during screening without ROP, 25 infants （48.1%） were discharged from screening with retinal vascularisation reaching zone III, 5 infants （9.6%） were treated with indirect diode with or without additional cryotherapy and 16 infants （30.8%） were lost to follow up. In this series gestational age rather than birth weight was found significantly correlated and predictive （P〈0.05） with ROP stages. CONCLUSION： ROP in a single site in upper Egypt appears to have comparable incidence to other areas worldwide. The main screening obstacle was missing cases due to the absence of a national ROP screening protocol.

关键词： retinopathy of prematurity incidence inEgypt neonatal screening

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Impact Excitations of Hydrogen Atoms in Collisions with Protons and Antiprotons

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Chinese Physics Letters 2014年第8期31卷 53-57页

作者： RedaS.Tantawi T.E.I.nassar MathematicsDepartment FacultyofScienceZagazigUniversityZagazigEgypt BasicScienceDepartment HigherTechnologicalInstituteTenthofRamadaCityEgypt

The direct impact excitations of ground-state hydrogen atoms by protons and antiprotons are investigated by using an impact parameter treatment. The calculations are performed within the solution of the coupled differential equations arising from the one-center atomic-orbital close-coupling approach as well as the impact parameter version of the first and second Born approximations. We have considered calculations that allow couplings to the n=1-5 states （up to g sub-levels） of the target atom as well as others, which neglect the effect of all states other than the initial and final states of the target atom. The sensitivity of the cross sections to the charge of the projectile is studied. The calculated cross sections are compared with those obtained by previous theoretical and experimental results.

关键词： HYDROGEN atom RESEARCH ATOMS PROTONS DIFFERENTIAL equations BORN approximation

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A New Three-Parameter Inverse Weibull Distribution with Medical and Engineering Applications

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Computer Modeling in Engineering & Sciences 2023年第5期135卷 1255-1274页

作者： Refah Alotaibi Hassan Okasha Hoda Rezk Mazen nassar Department of Mathematical Sciences College of SciencePrincess Nourah bint Abdulrahman UniversityRiyadh11671Saudi Arabia Department of Statistics Faculty of ScienceKing Abdulaziz UniversityJeddah21589Saudi Arabia Department of Mathematics Faculty of ScienceAl-Azhar UniversityNasr City11884CairoEgypt Department of Statistics Faculty of CommerceAl-Azhar UniversityNasr City11884CairoEgypt Department of Statistics Faculty of CommerceZagazig UniversityZagazig44519Egypt

The objective of this article is to provide a novel extension of the conventional inverse Weibull distribution that adds an extra shape parameter to increase its *** addition is beneficial in a variety of fields,including reliability,economics,engineering,biomedical science,biological research,environmental studies,and *** modeling real data,several expanded classes of distributions have been *** modified alpha power transformed approach is used to implement the new *** datamatches the new inverseWeibull distribution better than the inverse Weibull distribution and several other competing *** appears to be a distribution designed to support decreasing or unimodal shaped distributions based on its *** expressions for quantiles,moments,incomplete moments,moment generating function,characteristic generating function,and entropy expression are among the determined attributes of the new *** point and interval estimates are studied using the maximum likelihood *** research is conducted to illustrate the correctness of the theoretical *** applications to medical and engineering data are utilized to illustrate the model’s flexibility.

关键词： Inverse weibull distribution modified alpha power transformation method moments order statistics

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A Novel Modified Alpha Power Transformed Weibull Distribution and Its Engineering Applications

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Computer Modeling in Engineering & Sciences 2023年第6期135卷 2065-2089页

作者： Refah Alotaibi Hassan Okasha Mazen nassar Ahmed Elshahhat Department of Mathematical Sciences College of SciencePrincess Nourah bint Abdulrahman UniversityP.O.Box 84428Riyadh11671Saudi Arabia Department of Statistics Faculty of ScienceKing Abdulaziz UniversityJeddah80200Saudi Arabia Department of Mathematics Faculty of ScienceAl-Azhar UniversityNasr CityCairo11884Egypt Department of Statistics Faculty of CommerceZagazig UniversityZagazig44519Egypt Faculty of Technology and Development Zagazig UniversityZagazig44519Egypt

This paper suggests a new modified version of the traditional Weibull distribution by adding a new shape parameter utilising the modified alpha power transformed *** refer to the new model as modified alpha power transformed Weibull *** attractiveness and significance of the new distribution lie in its power to model monotone and non-monotone failure rate functions,which are quite familiar in environmental *** hazard rate function can be decreasing,increasing,bathtub and upside-down then bathtub *** structural properties of the proposed model are acquired including quantile function,moments,entropies,order statistics,residual life and reversed failure rate *** parameters of the distribution were estimated using the maximum likelihood *** maximum likelihood method is employed to estimate the model parameters and the approximate confidence intervals are also *** a simulation study,the performance of the point and interval estimates are compared using different *** real lifetime data sets,we verify that the offered model furnishes a better fit than some other lifetime models including Weibull,gamma and alpha powerWeibull models.

关键词： Weibull distribution modified alpha power transformationmethod maximum likelihood entropy order statistics

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REFLECTION CHARACTERISTICS OF LONGITUDINAL WAVES IN A SEMI-INFINITE CYLINDRICAL ROD CONNECTED TO AN INFINITE VISCOELASTIC STRATUM

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Acta Mechanica Solida Sinica 1996年第1期9卷 66-80页

作者： A.Moussa S.Bichir M.nassar Department of Engineering Mathematics and Physics Faculty of EngineeringCairo UniversityGizaEgypt

Reflection characteristics of longitudinal strain waves in a semi-infinite elastic rod con- nected to a viscoelastic stratum are investigated *** three-dimensional viscoelasticity the- ory is applied to the stratum,and the Laplace transform with respect to time and the numerical inverse Laplace transform by means of Laguerre function are *** time histories for the longitudinal strain of an arbitrary point of the rod are *** typical viscoelastic models are considered, one is the usual Maxwell-Voigt model,the other is whose relaxation function is given by a power law. The numerical results for the two models are presented and compared each other and also with previ- ously published results for the elastic stratum.

关键词： viscoelastic stratum Laplace transform

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