Background : Diabetes mellitus is a stressful condition in which the increased production of free radicals impairs the generation of naturally occurring antioxidants like vitamins and
carotenoids .
Aim :The present study deals with the changes in serum ß-carotene in type 2 diabetes mellitus, as modulated by glycemic control and oxidative stress .
Subjects & methods : Multiple biochemical parameters were obtained from plasma of 57 patients with type 2 diabetes mellitus ( 25 males and 32 females ) , on oral hypoglycemic with
a disease duration of 1- 15 years and 37 healthy normal subject s of matching age and sex to serve as controls. The biochemical parameters measured in the present study included the glycated Hb (HbA1c ), serum lipids ( total cholesterol TC, triglycerides TG , high and low density lipoprotein cholesterols , HDL-C & LDL-C ) , lipid peroxides and serum ß-carotene.
results revealed a marked reduction of ß- carotene in the diabetics in a pattern proportional to that of the glycemic control ,dyslipidemia and oxidative stress .
Possible causes , mechanisms and suggestions underlining these changes are discussed.
In this study, the stress-strength model R = P(Y < X < Z) is discussed as an important parts of reliability system by assuming that the random variables follow Invers Rayleigh Distribution. Some traditional estimation methods are used to estimate the parameters namely; Maximum Likelihood, Moment method, and Uniformly Minimum Variance Unbiased estimator and Shrinkage estimator using three types of shrinkage weight factors. As well as, Monte Carlo simulation are used to compare the estimation methods based on mean squared error criteria.
In this paper, the reliability of the stress-strength model is derived for probability P(Y<X) of a component having its strength X exposed to one independent stress Y, when X and Y are following Gompertz Fréchet distribution with unknown shape parameters and known parameters . Different methods were used to estimate reliability R and Gompertz Fréchet distribution parameters, which are maximum likelihood, least square, weighted least square, regression, and ranked set sampling. Also, a comparison of these estimators was made by a simulation study based on mean square error (MSE) criteria. The comparison confirms that the performance of the maximum likelihood estimator is better than that of the other estimators.
In this paper, estimation of system reliability of the multi-components in stress-strength model R(s,k) is considered, when the stress and strength are independent random variables and follows the Exponentiated Weibull Distribution (EWD) with known first shape parameter θ and, the second shape parameter α is unknown using different estimation methods. Comparisons among the proposed estimators through Monte Carlo simulation technique were made depend on mean squared error (MSE) criteria
The effect of UV-light on the tensile properties of pure PC has been studied. It was shown that irradiation of PC undergo a drop in the tensile properties of 30 hour of exposure. The results of irradiated samples shows that the addition of ZnO and TiO2 with different percentages (0.5, 1, 1.5 %) will reduce the Young modulus and ultimate stress of PC/ZnO ,PC/ TiO2 composites