Thermal stresses in functionally graded hollow sphere due to non-uniform internal heat generation

In this article, the thermal stresses in a hollow thick sphere of functionally graded material subjected to non-uniform internal heat generation are obtained as a function of radius to an exact solution by using the theory of elasticity. Material properties and heat generation are assumed as a function of radius of sphere and Poisson’s ratio as constant. The distribution of thermal stresses for different values of the powers of the module of elasticity and varying power law index of heat generation is studied. The results are illustrated numerically and graphically

Use of proton pump inhibitors in dialysis unit in tertiary care hospital: a pharmaco-epidemiological study

Background: Proton pump inhibitors (PPI) are generally thought to be safer drug with fewer adverse effects. Though this class of the drug is thought to be well tolerated, a detail study about actual use of these agents in nephrology department is still awaited in many parts of India. There had been case reports and case series which were reporting PPIs producing acute interstitial nephritis progressing to acute renal failure. The risk of PPI treatment in haemodialysis patients remains unexplored. The aim of the study was to evaluate a drug utilization of PPI in patient undergoing haemodialysis procedure.Methods: In this study every day visit to the dialysis units of the hospitals was carried out. After taking consent from the patients, the information from the case-report form was noted like; age, sex, diagnosis, laboratory reports and drug prescried. No personally identifiable information about patient or physician was collected. After this an interview of patients was taken.Results: In this study, out of 126 patients 76.6% were male and 23.4% were female. Out of these 126 patients 88.89% patients were on PPI. Nearly 54% were using PPI for more than six months. Nearly 29% patients were using PPI for more than 12 months.Conclusions: As many case-reports and studies are suggesting, there is co-relation of PPI and acute interstitial nephritis from this study we suggest that especially in nephrology unit patients’, more caution must be exercised while using PPI

Thermal stresses in an infinite body with spherical cavity due to an arbitrary heat flux on its internal boundary surface

In this paper we consider an elastic infinite body with a spherical cavity subjected to a arbitrary heat flux on its internal boundary which is assumed to be traction free. The displacement and thermal stresses are obtained and results are compared using constant and time dependent heat flux. Laplace transform technique is used to obtain the temperature distribution. The mathematical model is obtained for copper material. The results are illustrated numerically and graphically

Symmetry breaking perturbations and strange attractors

The asymmetrically forced, damped Duffing oscillator is introduced as a prototype model for analyzing the homoclinic tangle of symmetric dissipative systems with \textit{symmetry breaking} disturbances. Even a slight fixed asymmetry in the perturbation may cause a substantial change in the asymptotic behavior of the system, e.g. transitions from two sided to one sided strange attractors as the other parameters are varied. Moreover, slight asymmetries may cause substantial asymmetries in the relative size of the basins of attraction of the unforced nearly symmetric attracting regions. These changes seems to be associated with homoclinic bifurcations. Numerical evidence indicates that \textit{strange attractors} appear near curves corresponding to specific secondary homoclinic bifurcations. These curves are found using analytical perturbational tools

Universal behaviour of entrainment due to coherent structures in turbulent shear flow

I suggest a solution to a persistent mystery in the physics of turbulent shear flows: cumulus clouds rise to towering heights, practically without entraining the ambient medium, while apparently similar turbulent jets in general lose their identity within a small distance through entrainment and mixing. From dynamical systems computations on a model chaotic vortical flow, I show that entrainment and mixing due to coherent structures depend sensitively on the relative speeds of different portions of the flow. A small change in these speeds, effected for example by heating, drastically alters the sizes of the KAM tori and the chaotic mixing region. The entrainment rate and, hence, the lifetime of a turbulent shear flow, shows a universal, non-monotone dependence on the heating.Comment: Preprint replaced in order to add the following comment: accepted for publication in Phys. Rev. Let