Showing papers by "Government College published in 1997"

Antimicrobial activity of some marine algae of southwest coast of India

Abstract: Acetone and ethanol extracts of five marine algae namely Caulerpa taxifolia, Chaetomorpha antennina, Cladophora fascicularis, Ulva lactuca and Gracilaria corticata collected from two locations in three seasons were tested for the growth inhibition of five bacteria and three fungi. Caulerpa taxifolia, Chaetomorpha antennina and Gracilaria corticata exhibited considerable inhibition against bacterium Bacillus subtilis and yeast Candida albicans. Distal parts of algae of summer season showed good inhibitory activity. None of the algal extracts inhibited bacterium Pseudomonas aeruginosa, fungi Aspergillus flavus and Fusarium oxysporum. A significant difference (p<0.01, ANOVA) in antibacterial activity of the extracts of Chaetomorpha antennina was found in different seasons. Significant difference (p<0.001, ANOVA) was also found in the inhibitory activities of acetone extracts of distal and proximal parts of Chaetomorpha antennina of summer. No relation was found between microbial growth inhibition and phenolic content of algae.

A pseudopotential approach to the superconducting state properties of Cu–Zr metallic glasses

Abstract: The superconducting state properties of the metallic glass have been investigated in the BCS - Eliashberg - McMillan framework by extending this theory to the binary metal glasses. Pseudo ions with average properties have been considered to replace both types of ions in the system. Values of the superconducting state parameters, namely electron - phonon coupling strength , Coloumb pseudopotential , transition temperature , isotope effect exponent and interaction strength have been worked out using Ashcroft's potential and the linear potential due to Sharma and Kachhava along with six different forms of dielectric screening. The form factors directly obtained from the screened pseudopotential of Veljkovic and Slavic have also been used to explicitly observe the effect of the dielectric screening on and through . The results obtained established the presence of a superconducting phase in glass.

Error bounds and parameter choice strategies for simplified regularization in Hilbert scales

Abstract: Simplified regularization in the setting of Hilbert scales has been considered for obtaining stable approximate solutions for ill-posed operator equations. The derived error estimates using an a posteriori as well as an a priori parameter choice strategy are shown to be of optimal order with respect to certain natural assumptions on the ill-posedness of the equation.

Global monopole in scalar tensor theory

Abstract: The well known monopole solution of Barriola and Vilenkin (BV) resulting from the breaking of a global SO(3) symmetry is extended in general relativity along with a zero mass scalar field and also in Brans-Dicke(BD) theory of this http URL the case of BD theory, the behaviour of spacetime and other variables such as BD scalar field and the monopole energy density have been studied numerically.For monopole along with a zero mass scalar field, exact solutions are obtained and depending upon the choice of arbitary parameters, the solutions either reduce to the BV case or to a pure scalar field solution as special this http URL is interesting to note that unlike the BV case the global monopole in the BD theory does exert gravitational pull on a test particle moving in its spacetime.

Alluvial fan sedimentation in the Cretaceous Athgarh Gondwana basin, Orissa, India

Abstract: The Athgarh Formation forms an important stratigraphic unit of Upper Gondwana sediments of Peninsular India. The regional palaeocurrent indicates a consistent southeasterly dispersal of clastics from the Archaean source terrain located to the northwest of the basin. The Athgarh Formation represents deposition in an alluvial fan environment with the development of proximal, mid-, and distal fan subenvironments and the distal part of the fan merging into a lake. The buildup of the Athgarh alluvial fan system occurred in a humid climate. Stream-flow processes dominated and a fan was drained by braided channels. Debris flow processes also operated, but were prominent only in the proximal fan zone. Several fans coalesced along the basin margin, forming a southeasterly sloping, broad and extensive alluvial plain terminating to a lake in the center of the basin. Aggradation of fans along the subsiding margin of the basin resulted in the Athgarh succession showing a remarkable lateral facies change in the down-slope direction. The proximal fan conglomerates pass into the sandstone-dominated mid-fan deposits, which, in turn, grades into the cyclic sequences of sandstones and mudstones of a distal fan origin. Further down slope, thick sequence of lacustrine shales occurs.

A theoretical verification of intensity of plasmaspheric ELF hiss emissions: theory versus GEOS-1 observations

Abstract: An attempt is made to confirm the generation mechanism of plasmaspheric ELF hiss emissions observed aboard GEOS-1 satellite in the equatorial region both at small and large wave normal angles by calculating their magnetic field intensities in terms of incoherent Cerenkov radiation mechanism and cyclotron resonance instability mechanism, using appropriate and suitable plasma parameters. The ELF intensities calculated by Cerenkov radiation mechanism, being 4 to 5 orders of magnitude lower than the observed intensities, rule out the possibility of their generation by this mechanism. On the other hand, the intensities calculated under electron cyclotron resonance instability mechanism are found to be large enough to account for both the observed intensity and propagation losses and hence to confirm that plasmaspheric ELF hiss emissions observed aboard GEOS-1 satellite both at small and large wave normal angles were originally generated in the equatorial region by this mechanism just near the inner edge of the plasmapause. The difference in the observed intensities of two types of the emissions has been attributed to the propagation effect rather than the generation efffect.

Lamperti-type operators on a weighted space of continuous functions

Abstract: For a locally convex Hausdorff topological vector space E and for a system V of weights vanishing at infinity on a locally compact Hausdorff space X, let CV0(X,E) be the weighted space of E-valued continuous functions on X with the locally convex topology derived from the seminorms which are weighted analogues of the supremum norm. A characterization of the orthogonality preserving (Lamperti-type) operators on CV0(X,E) is presented in this paper.