1,879 research outputs found
Bond percolation of polymers
We study bond percolation of non-interacting Gaussian polymers of
segments on a 2D square lattice of size with reflecting boundaries. Through
simulations, we find the fraction of configurations displaying {\em no}
connected cluster which span from one edge to the opposite edge. From this
fraction, we define a critical segment density and the
associated critical fraction of occupied bonds , so that they
can be identified as the percolation threshold in the limit.
Whereas is found to decrease monotonically with for a
wide range of polymer lengths, is non-monotonic. We give
physical arguments for this intriguing behavior in terms of the competing
effects of multiple bond occupancies and polymerization.Comment: 4 pages with 6 figure
Comparative study of magnetic and magnetotransport properties of Sm0.55Sr0.45MnO3 thin films grown on different substrates
Highly oriented polycrystalline SSMO thin films deposited on single crystal
substrates by ultrasonic nebulized spray pyrolysis have been studied. The film
on LAO is under compressive strain while LSAT and STO are under tensile strain.
The presence of a metamagnetic state akin to cluster glass formed due to
coexisting FM and antiferromagnetic/charge order (AFM/CO) clusters. All the
films show colossal magnetoresistance but its temperature and magnetic field
dependence are drastically different. In the lower temperature region the
magnetic field dependent isothermal resistivity also shows signature of
metamagnetic transitions. The observed results have been explained in terms of
the variation of the relative fractions of the coexisting FM and AFM/CO phases
as a function of the substrate induced strain and oxygen vacancy induced
quenched disorder.Comment: 21 page
Aerosol Characteristics at a high-altitude station Nainital during the ISRO-GBP Land Campaign-II
During the second land campaign (LC-II) organised by ISRO-GBP, extensive
ground-based measurements of aerosol characteristics were carried out over
Manora Peak (29.4oN; 79.5oE; 1951 metres above mean sea level), Nainital (a
high altitude station located in the Shivalik ranges of Central Himalayas)
during the dry, winter season (December) of 2004. These measurements included
the spectral aerosol optical depths (AOD), columnar water vapour content (W),
Total Columnar Ozone (TCO), total number concentration (NT) of near surface
aerosols, mass concentration of black carbon (MB), aerosol mass loading (MT),
and Global Solar Radiation. Based on these measured parameters, we present the
results on the near-surface and columnar properties of atmospheric aerosols at
Nainital.Comment: Published in the Proceedings of the ISRO-GBP Land-Campaign-II
meeting, Physical Research Laboratory, Ahmadabad (Inida), March 200
Interactions of the channel forming peptide alamethicin with artificial and natural membranes
Alamethicin and related α-aminoisobutyric acid peptides form transmembrane channels across lipid bilayers. This article briefly reviews studies on the effect of alamethicin on lipid phase transitions in lipid bilayers and on mitochondrial oxidative phosphorylation. Fluorescence polarization studies, employing 1,6-diphenyl-1,3,5-hexatriene as a probe, suggest that alamethicin fluidizes lipid bilayers below the phase transition t-emperature, but has little effect above the gel-liquid crystal transition point. Alamethicin is shown to function as an uncoupler of oxidative phosphorylation in rat liver mitochondria. The influence of alamethicin on mitochondrial respiration is modulated by the phosphate ion concentration in the medium. Classical uncoupling activity is evident at low phosphate levels while inhibitory effects set in at higher phosphate concentrations. Time-dependent changes in respiration rates following peptide addition are rationalized in terms of alamethicin interactions with mitochondrial membrane components
Recent applications of gallium and gallium halides as reagents in organic synthesis
This review highlights the application of gallium metal and gallium halides as reagents in organic synthesis. Owing to their unique catalytic properties, gallium trihalides are considered effective Lewis acids which can activate several functional groups under extremely mild conditions. Gallium halides have been successfully employed as Lewis acid catalysts in various organic transformations such as alkylation, allylation, radical reactions, cycloaddition reactions, Friedel-Craft’s reactions and various coupling reactions. This review seeks to update organic chemists about the potential application of gallium halides in the synthesis of a wide variety of chemical building blocks
A Study on Non-Revenue Water in Intermittent and Continuous Water Service in Hubli City, India
The Cities in developing countries generally have high levels of non-revenue water (NRW), which requires high attention. In parts of Hubli-Dharwad in India, a study was conducted to assess NRW in one of the intermittent water service (IWS) pilot area and also in newly constructed continuous water service (CWS) demonstration zone. The study revealed that the NRW in IWS is as high as 37%, whereas in CWS, it is limited to about 15%. The outcome of this study will be helpful in CWS scaling up projects in India and developing countries. Keywords: Intermittent water service, Continuous water service, Non-revenue water, Physical losses, Commercial losse
SIMPle Dark Matter: Self-Interactions and keV Lines
We consider a simple supersymmetric hidden sector: pure SU(N) gauge theory.
Dark matter is made up of hidden glueballinos with mass and hidden
glueballs with mass near the confinement scale . For and , the glueballinos freeze out
with the correct relic density and self-interact through glueball exchange to
resolve small-scale structure puzzles. An immediate consequence is that the
glueballino spectrum has a hyperfine splitting of order . We show that the radiative decays of the excited state can
explain the observed 3.5 keV X-ray line signal from clusters of galaxies,
Andromeda, and the Milky Way.Comment: v1: 6 pages, 2 figures; v2: added references, published version; v3:
note adde
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