Showing papers by "Shiv Nadar University published in 2004"

Cathodoluminescence versus dynamical epitaxy of Ba-ion irradiated α-quartz

Abstract: Doping α-quartz with photoactive ions without destroying its crystalline structure appears to be a promising way to tune its luminescent and structural properties. We have achieved dynamic solid phase epitaxial regrowth and cathodoluminescence of 175keV Ba-ion irradiated α-quartz in the temperature range from 300 to 1170K. Rutherford Backscattering Channeling analysis showed that the amorphous layer produced by 1×1015 Baions∕cm2 at 300K had almost disappeared at an implantation temperature of 1123K. Room temperature cathodoluminescence exhibited dramatic changes in the optical spectra as a function of the implantation temperature and allowed to distinguish between color centers related to quartz, ion-irradiated silica and implanted Ba. Between 770 and 1100K, room-temperature cathodoluminescence showed a predominant blue and other weak bands connected to various known defects in the Si-O-Si network. However, after achieving almost complete solid phase epitaxial recovery, only a violet band at 3.4eV remai...

Information Extraction from Hindi Texts

Abstract: The paper presents an information extraction system that takes input from Hindi texts and improves the information content retrieved by using anaphor/pronoun resolution mechanism The information extraction system developed consists of three major modules: The language Parser, Resolution System and Information Extractor The language parser used is HPSG (Head-Driven Phrase Structure Grammar) based that provides both syntactic and semantic information to the anaphor resolution system HPSG was chosen because it provides a set of constraint on the co-referential structures in the language, which bounds the search for an antecedent to a more precise location in the discourse The semantic information included in its parsing may be helpful for removing ambiguity in anaphor/pronoun resolution The anaphor resolution system uses few heuristic rules to resolve intrasentential references while centering theory is used for intersentential resolution

Quantity Controls, License Transferability, and the Level of Investment

Abstract: This paper models investment/entry decisions in a competitive industry that is subject to a quantity control, either on output or on a production input. The quantity control is implemented via the sale of licenses for the restricted output/input. We show that liberalizing the quantity control could reduce investment in the industry under certain circumstances. Furthermore, the level of investment in the industry is different depending on whether the licenses are tradable or not. Key factors to consider are the elasticity of demand for the final good and the degree of input substitutability. Two examples are presented to illustrate the results.

Theory of the fundamental linewidth of a two-mode laser

Abstract: Starting from the field master equation for a laser oscillating simultaneously in two modes, we probe the dependence of its fundamental phase-diffusion linewidth on the degree of coupling between the two modes. We find that the heterodyned intrinsic linewidth shows the usual decrease when the output power of each mode increases with an increase in the gain, while the nonlinear self-saturation and cross-coupling coefficients are held constant. The linewidth also decreases with increase in the cross-coupling between the modes for constant gain when the output power of each mode is kept constant by decreasing the self-saturation coefficient. The linewidth, however, increases with increasing cross-coupling when (a) the gain and the self-saturation coefficient are held constant and hence the output power in each mode decreases and (b) the gain is increased keeping the output power and the self-saturation of each mode constant.