Induced geomagnetic variation and crustal evolution of the southern peninsula of India

The current thinking on crustal evolution and the influence of Precambrian lineaments on tectonism and mineralization provide support for the conjecture that zones of high electrical conductivity exist in the crust which are related to the tectonic and mineralized zones. Studies by the present authors using geological and tectonic data from remote sensing techniques, in particular, together with relevant data on anomalous geomagnetic variations reported in this paper would serve as additional contribution towards the global model.     

The relevance of the Eddington limit to thick accretion disks

Thick accretion disks with narrow funnels around massive black holes are considered promising models for active galactic nuclei. These models assume a supercritical accretion rate and emit collimated beams with super-Eddington luminosities. We have made approximate calculations of the interaction between the emerging radiation and the walls for an optically thin funnel. The results are sensitive to the sound velocity and to the viscosity parameter α. They suggest that a significant particle luminosity can accompany the radiation in the super-Eddington case. By applying an Eddington type limit based on mechanical equilibrium to a suitably chosen interior surface in the disk, we find that energy transport, if radiative, can strongly limit the efficiency of these models.