Causality Implies Inflationary Back-Reaction

There is a widespread belief among inflationary cosmologists that a local observer cannot sense super-horizon gravitons. The argument goes that a local observer would subsume super-horizon gravitons into a redefinition of his coordinate system. We show that adopting this view for pure gravity on de Sitter background leads to time variation in the Hubble parameter measured by a local observer. It also leads to a violation of the gravitational field equation $R = 4 \Lambda$ because that equation is obeyed by the full metric, rather than the one which has been cleansed of super-horizon modes.Comment: 20 pages, 2 figures, uses LaTeX2e, version 2 slightly revised for publicatio

Modified Bethe-Weizsacker mass formula with isotonic shift and new driplines

Nuclear masses are calculated using the modified Bethe-Weizsacker mass formula in which the isotonic shifts have been incorporated. The results are compared with the improved liquid drop model with isotonic shift. Mass excesses predicted by this method compares well with the microscopic-macroscopic model while being much more simple. The neutron and proton drip lines have been predicted using this modified Bethe-Weizsacker mass formula with isotonic shifts.Comment: 9 pages including 2 figure

Folding model analysis of proton radioactivity of spherical proton emitters

Half lives of the decays of spherical nuclei away from proton drip line by proton emissions are estimated theoretically. The quantum mechanical tunneling probability is calculated within the WKB approximation. Microscopic proton-nucleus interaction potentials are obtained by single folding the densities of the daughter nuclei with M3Y effective interaction supplemented by a zero-range pseudo-potential for exchange along with the density dependence. Strengths of the M3Y interaction are extracted by fitting its matrix elements in an oscillator basis to those elements of the G-matrix obtained with the Reid-Elliott soft-core nucleon-nucleon interaction. Parameters of the density dependence are obtained from the nuclear matter calculations. Spherical charge distributions are used for calculating the Coulomb interaction potentials. These calculations provide reasonable estimates for the observed proton radioactivity lifetimes of proton rich nuclei for proton emissions from 26 ground and isomeric states of spherical proton emitters.Comment: 6 page

Gravity of higher-dimensional global defects

Solutions of Einstein's equations are found for global defects in a higher-dimensional spacetime with a nonzero cosmological constant Lambda. The defect has a (p-1)-dimensional core (brane) and a `hedgehog' scalar field configuration in the n extra dimensions. For Lambda = 0 and n > 2, the solutions are characterized by a flat brane worldsheet and a solid angle deficit in the extra dimensions. For Lambda > 0, one class of solutions describes spherical branes in an inflating higher-dimensional universe. Instantons obtained by a Euclidean continuation of such solutions describe quantum nucleation of the entire inflating brane-world, or of a spherical brane in an inflating higher-dimensional universe. For Lambda < 0, one class of solutions exhibits an exponential warp factor. It is similar to spacetimes previously discussed by Randall and Sundrum for n = 1 and by Gregory for n = 2.Comment: 18 pages, no figures, uses revte

Coal Processing in Indian Context

Coal processing in the Indian context as projected till the turn of the country requires to be viewed in cons-ideration of the various factors viz. (i) the type and quality of coal likely to be available including its prod-uction source i.e. whether from underground or open cast mine; (ii) the reserve potential of coal resources that may have to be progressively consumed by the consumer sectors; (iii) the coal demand forecast for the various sectors for tie-up with indigenous coal sources for such uses; (iv) industrial application prospects of new technologies since developed (for maximised use of indigenous coal resource) etc

How much do helioseismological inferences depend upon the assumed reference model?

We investigate systematic uncertainties in determining the profiles of the solar sound speed, density, and adiabatic index by helioseismological techniques. We find that rms uncertainties-averaged over the sun of ~ 0.2%-0.4% are contributed to the sound speed profile by each of three sources: 1)the choice of assumed reference model, 2) the width of the inversion kernel, and 3) the measurements errors. The density profile is about an order of magnitude less well determined by the helioseismological measurements. The profile of the adiabatic index is determined to an accuracy of about 0.2% . We find that even relatively crude reference models yield reasonably accurate solar parameters.Comment: Accepted for publication in ApJ . Related material at http://www.sns.ias.edu/~jn