869 research outputs found

    Lower mass limit of an evolving interstellar cloud and chemistry in an evolving oscillatory cloud

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    Simultaneous solution of the equation of motion, equation of state and energy equation including heating and cooling processes for interstellar medium gives for a collapsing cloud a lower mass limit which is significantly smaller than the Jeans mass for the same initial density. The clouds with higher mass than this limiting mass collapse whereas clouds with smaller than critical mass pass through a maximum central density giving apparently similar clouds (i.e., same Av, size and central density) at two different phases of its evolution (i.e., with different life time). Preliminary results of chemistry in such an evolving oscillatory cloud show significant difference in abundances of some of the molecules in two physically similar clouds with different life times. The problems of depletion and short life time of evolving clouds appear to be less severe in such an oscillatory cloud

    On non-LTE H<SUB>2</SUB><SUP>+</SUP> as missing solar opacity

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    A careful examination has revealed that use of incomplete reaction processes and incorrect rates have led Krishna Swamy and Stecher to overestimate the H2+ opacity by a factor of 104 at &#955; = 2000 &#197;. H2+ is not a significant source of opacity in the solar atmosphere

    A study of the Variation of Daily O3 Concentration at Halley Bay in Antarctica with Daily Solar UV Flux

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    Monitoring of wild pseudomonas biofilm strain conditions using statistical characterization of scanning electron microscopy images

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    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.The present paper proposes a novel method of quantification of the variation in biofilm architecture, in correlation with the alteration of growth conditions that include variations of the substrate and conditioning layer. The polymeric biomaterials serving as substrates are widely used in implants and indwelling medical devices, while the plasma proteins serve as the conditioning layer. The present method uses descriptive statistics of field emission scanning electron microscopy (FESEM) images of biofilms obtained during a variety of growth conditions. We aim to explore here the texture and fractal analysis techniques, to identify the most discriminatory features which are capable of predicting the difference in biofilm growth conditions. We initially extract some statistical features of biofilm images on bare polymer surfaces, followed by those on the same substrates adsorbed with two different types of plasma proteins, viz., bovine serum albumin (BSA) and fibronectin (FN), for two different adsorption times. The present analysis has the potential to act as a futuristic technology for developing a computerized monitoring system in hospitals with automated image analysis and feature extraction, which may be used to predict the growth profile of an emerging biofilm on surgical implants or similar medical applications.SDS acknowledges the funding from the Department of Science and Technology (DST), Govt. of India through the Women’s Scientist Scheme – A, project no. LS-466/WOS A/2012-2013

    Condensation and Evaporation of Mutually Repelling Particles :Steady states and limit cycles

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    We study condensation and evaporation of particles which repel each other, using a simple set of rules on a square lattice. Different results are obtained for a mobile and an immobile surface layer.A two point limit cycle is observed for high temperature and low pressure in both cases. Here the coverage oscillates between a high and a low value without ever reaching a steady state. The results for the immobile case depend in addition on the initial coverage.Comment: 8 pages, 3 figure
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