Showing papers by "Celal Bayar University published in 1996"

Symmetry groups of boundary layer equations of a class of non-Newtonian fluids

Abstract: A non-Newtonian fluid model in which the stress is an arbitrary function of the symmetric part of the velocity gradient is considered. Symmetry groups of the two-dimensional boundary layer equations of the model are found by using exterior calculus. The complete isovector field corresponding to some cases, such as arbitrary shear function, Newtonian fluids, and powerlaw fluids, are found. Similarly, solutions for some special transformations are presented. Results obtained in a previous paper [M. Pakdemirli, Int. J. Non-Linear Mech. 29, 187 (1994)] using special groups of transformations (scaling, spiral) are verified in this study using a general approach.

Effects of passive exposure to tobacco, socioeconomic status and a family history of essential hypertension on lipid profiles in children.

Abstract: There is abundant evidence that the atherosclerotic process begins in childhood. Dyslipidemia is a major risk factor for atherosclerosis in adults and children. In the present study, we measured serum lipoprotein concentrations in 194 healthy children aged between 4 to 14 years. Children were grouped according to the socioeconomic status of the families, family history of essential hypertension and passive tobacco exposure. The values of total cholesterol, low density lipoprotein cholesterol and the ratio of total cholesterol/high density lipoprotein cholesterol in the low socioeconomic group were found to be significantly higher than the values obtained for the middle-high socioeconomic group. The values of total cholesterol, low density lipoprotein cholesterol, the ratio of total cholesterol/high density lipoprotein cholesterol and low density lipoprotein cholesterol/high density lipoprotein cholesterol in the passive smoker group were found to be significantly higher than those of the nonsmoker group. But, the socioeconomic level in the passive smoker group was found to be significantly lower than that of the nonsmoker group, and therefore, the impact of passive smoking on the serum lipids in children was related to socioeconomic status. A significant difference in terms of blood lipid fractions between the groups with and that without a family history of essential hypertension was not found. These results suggest that passive smoking and lower socioeconomic status are important risk factors for cardiovascular heart disease, while a positive family history of essential hypertension is not an important risk factor.

A new approach for arrhythmia classification

Abstract: The ECG signal is formed of the P wave, the QRS complex and the T wave The P wave appears as a result of QRS complex ventricle contraction because of electrical stimulation initiation at the sinoatrial node and spreading in the cardiac muscles The T wave appears as a result of ventricle relaxation In this study the ECG signal is analyzed in the time domain For this purpose, arrhythmia are determined by taking related mean time intervals of ECG as feature extraction Arrhythmia are categorized by applying time elapsed between two R waves (RR intervals), appearing in ECG signals, as the input for artificial neural networks

Diastolic Spectrum of Left-Ventricular Hypertrophy: The Impact of Etiology and Coronary Artery Disease on Doppler Transmitral Velocity

Abstract: Diastolic filling of hypertrophied left ventricles has frequently been observed by Doppler methods. We hypothesized that filling characteristics in hypertrophy vary with etiology and concurrent ischem

Zinc tolerance test patterns in normal children and in moderate and severe zinc deficiency states.

Abstract: Twenty-six normal, 38 moderately and 14 severely zinc-deficient children, aged 2–12 years, were examined by clinical and laboratory approaches. After fasting-blood sampling, 120 mg zinc sulphate (25 mg elemental zinc) were administerd orally to each group of children, to obtain zinc tolerance curve patterns. Sampling proceeded to the 2nd and 4th hours of the loadingtest period. Plasma zinc was assessed on an atomic absorption spectrophotmeter. In normal children, at the 2nd hour of loading, a significant (p < .001) elevation (1.764 ± 0.133 mg/l) in the mean (± SEM) plasma zinc level was noted; also at the 4th hour a significant (p < .001) decrease (1.506 + 0.123 mg/l) in the mean plasma zinc level was shown. The mean plasma zinc level at the 4th hour was found higher than the mean fasting plasma zinc level (1.054 +- 0.061 mg/l), but lower than the mean level found at the 2nd hour. In moderately zinc-deficient children, the rise in the 2nd hour and the fall in the 4th hour in the plasma zinc level were highly significant (p < .001 and p < .001, respectively) in relation to fasting blood level However, in severely zinc-deficient children, the intensity of the increase (0.746 + 0.147 mg/l) in plasma zinc level at the 2nd hour was of lesser significance (p < .006) and the fall (0.424 + 0.061) mg/l) at the 4th hour was not significant. Therefore, in children with normal plasma zinc levels, an increase of more than 0.50 mg/l was seen at the 2nd hour of loading. This rise was seen to persist at the 4th hour. However, in children with moderate zinc deficiency, although again an increase of 0.50 mg/l was seen at the 2nd hour this increase did not persist at the 4th hour; and the 4th-hour value showed a significant decrease in relation to the 2nd hour value. Whereas, in children with severe zinc deficiency the rise of plasma level at the 2nd hour was less than 0.5 mg/l and the fall at the 4th hour was to such a level which was not significant in relation to fasting zinc level. This could be due to enhanced uptake bf zinc off the circulation by the depleted tissues in severe zinc deficiency.