Relativistic Green functions in a plane wave gravitational background

We consider a massive relativistic particle in the background of a gravitational plane wave. The corresponding Green functions for both spinless and spin 1/2 cases, previously computed by A. Barducci and R. Giachetti \cite{Barducci3}, are reobtained here by alternative methods, as for example, the Fock-Schwinger proper-time method and the algebraic method. In analogy to the electromagnetic case, we show that for a gravitational plane wave background a semiclassical approach is also sufficient to provide the exact result, though the lagrangian involved is far from being a quadratic one.Comment: Last paper by Professor Arvind Narayan Vaidya, 18 pages, no figure

No news for Kerr-Schild fields

Algebraically special fields with no gravitational radiation are described. Kerr-Schild fields, which include as a concrete case the Kinnersley photon rocket, form an important subclass of them.Comment: 4 pages, Revtex

Flow Transients in Supercritical CO2 Natural Circulation Loop

AbstractA one-dimensional transient code is developed for studying the flow transient in the supercritical CO2 natural circulation loop. The transient code is validated with the experimental result. Various flow transients such as flow initiation, power step up and power step back have been studied. The effect of operational parameters and geometrical parameters on flow initiation transient also has been studied. In all cases steady state has been reached and instability is not observed in vertical heater vertical cooler configuration of supercritical CO2 natural circulation loop

Some results on total chromatic number of a graph

A total coloring of a graph is a proper coloring in which no two adjacent or incident graph elements receive the same color. The total chromatic number of a graph is the smallest positive integer for which the graph admits a total coloring. In this paper, we derive some results on total chromatic number of a graph.The present work is a part of the research work done under the Minor Research Project No. GUJCOST/MRP/2015-16/2620 of Gujarat Council on Science and Technology(GUJCOST).Publisher's Versio

A study on clinical profile of stroke in young and elderly in GMERS Medical College and Hospital, Gandhinagar, Gujarat

Background:The cerebrovascular stroke is one of the leading causes of morbidity & mortality in adult life. Indian studies have shown a stroke prevalence of 471.58/100000 population. Stroke mostly occurs in elderly people. Risk factors for stroke differ between young and elderly patients. The aim was to study the clinical presentation, risk factors, types, topography as per CT scan findings in ≤45 years and >45 years patients from GMERS medical college and hospital Gandhinagar.Methods:This is a retrospective study of all new patients managed for stroke in the medical ward of GMERS medical college and hospital, Gandhinagar, Gujarat from January1, 2012 to December 31, 2013.Results:Incidence of stroke in elderly (≥45 years) was than young (<45 years) patients with male predominance in both the groups. Most common clinical presentation from both age groups was hemiplegia (75% in young vs. 72.1% in elderly). Common risk factors in were HT and past h/o CVD (25%) and smoking (16.6%) in young and HT (37.1%), dyslipidemia and smoking (14.3%) in elderly. Most common type of stroke in both age groups was ischemic (83.3% in young vs. 73.2% in elderly), followed by Hemorrhagic. Common sites of hemorrhage in young and elderly were lobar and thalamoganglionic. Most common infarction site in both age groups is MCA territory.  Conclusion:The cerebrovascular stroke was more in elderly with hypertension and smoking was the most common risk factor in both age groups and most common type was ischemic.