284 research outputs found
Neutral Theory and Relative Species Abundance in Ecology
The theory of island biogeography[1] asserts that an island or a local
community approaches an equilibrium species richness as a result of the
interplay between the immigration of species from the much larger metacommunity
source area and local extinction of species on the island (local community).
Hubbell[2] generalized this neutral theory to explore the expected steady-state
distribution of relative species abundance (RSA) in the local community under
restricted immigration. Here we present a theoretical framework for the unified
neutral theory of biodiversity[2] and an analytical solution for the
distribution of the RSA both in the metacommunity (Fisher's logseries) and in
the local community, where there are fewer rare species. Rare species are more
extinction-prone, and once they go locally extinct, they take longer to
re-immigrate than do common species. Contrary to recent assertions[3], we show
that the analytical solution provides a better fit, with fewer free parameters,
to the RSA distribution of tree species on Barro Colorado Island (BCI)[4] than
the lognormal distribution[5,6].Comment: 19 pages, 1 figur
Proteins and polymers
Proteins, chain molecules of amino acids, behave in ways which are similar to
each other yet quite distinct from standard compact polymers. We demonstrate
that the Flory theorem, derived for polymer melts, holds for compact protein
native state structures and is not incompatible with the existence of
structured building blocks such as -helices and -strands. We
present a discussion on how the notion of the thickness of a polymer chain,
besides being useful in describing a chain molecule in the continuum limit,
plays a vital role in interpolating between conventional polymer physics and
the phase of matter associated with protein structures.Comment: 7 pages, 6 figure
Protective effect of ethanolic leaf extract of Alphonsea sclerocarpa against ethylene glycol induced urolithiasis in rats
252-258Alphonsea sclerocarpa Thwaites belonging to the family Annonaceae is a small tree, which grows up to 10-15 m tall the leaves are simple and alternate. Despite its medicinal properties the plant seems to be less explored and hence this research aims at exploring the antiurolithiatic activity of ethanolic leaf extract of A. sclerocarpa on ethylene glycol induced urolithiasis in rats. A. sclerocarpa leaf powder was extracted using ethanol. The effect of ethanolic leaf extract of A. sclerocarpa (250 and 500 mg/kg, p.o.) was studied in experimentally induced renal stone in rats by in vivo model. Ethylene glycol model (0.75% in drinking water, for 28 days) was used for renal stone induction. The blood, urine and kidney samples were used for various parameters. The concentration of calcium, oxalate, phosphorus, creatinine and blood urea nitrogen was observed in each group. The phytochemical analysis was carried out to detect the presence of secondary metabolites like saponins and flavonoids in the ethanolic extract of A. sclerocarpa leaf extract. In ethylene glycol (0.75% v/v) treated animal model ethanolic extract of A. sclerocarpa leaf extract showed significant results on stone promoters (calcium oxalate, inorganic phosphate and sodium), kidney function parameters (uric acid, blood urea nitrogen, creatinine). On the basis of biochemical parameters and histopathological study it was confirmed that A. sclerocarpa leaf extract protected the renal cells from oxidative stress and injury induce by calcium oxalate crystals. The investigation of ethanolic extract of A. sclerocarpa leaf has shown promising antiurolithiatic activity and support folklore claims of these plants as antiurolithiatic. The mechanism of action of these plants for antiurolithiatic is apparently related to increased diuresis and lowering of urinary concentrations of stone-forming constituents, though it should be confirmed by the extensive exploratory studies
Congenital Epulis in a Newborn: A Case Report, Immunoprofiling and Review of Literature
Background: Congenital epulis is a rare lesion of the newborn, presenting as mass in the oral cavity which can interfere with respiration and feeding. It should be distinguished from other lesions which can occur in newborns, both clinically and histopathologically.Case details: Here, we report a case of congenital epulis in a newborn female on the right alveolar ridge, along with an extensive review of literature and discuss the immunoprofiling.Conclusion: Early diagnosis of CE in a newborn is of paramount importance in the successful management of these rare cases.Keywords: congenital epulis, congenital granular cell lesion, Neumann’s tumo
Protective effect of ethanolic leaf extract of Alphonsea sclerocarpa against ethylene glycol induced urolithiasis in rats
Alphonsea sclerocarpa Thwaites belonging to the family Annonaceae is a small tree, which grows up to 10-15 m tall the leaves are simple and alternate. Despite its medicinal properties the plant seems to be less explored and hence this research aims at exploring the antiurolithiatic activity of ethanolic leaf extract of A. sclerocarpa on ethylene glycol induced urolithiasis in rats. A. sclerocarpa leaf powder was extracted using ethanol. The effect of ethanolic leaf extract of A. sclerocarpa (250 and 500 mg/kg, p.o.) was studied in experimentally induced renal stone in rats by in vivo model. Ethylene glycol model (0.75% in drinking water, for 28 days) was used for renal stone induction. The blood, urine and kidney samples were used for various parameters. The concentration of calcium, oxalate, phosphorus, creatinine and blood urea nitrogen was observed in each group. The phytochemical analysis was carried out to detect the presence of secondary metabolites like saponins and flavonoids in the ethanolic extract of A. sclerocarpa leaf extract. In ethylene glycol (0.75% v/v) treated animal model ethanolic extract of A. sclerocarpa leaf extract showed significant results on stone promoters (calcium oxalate, inorganic phosphate and sodium), kidney function parameters (uric acid, blood urea nitrogen, creatinine). On the basis of biochemical parameters and histopathological study it was confirmed that A. sclerocarpa leaf extract protected the renal cells from oxidative stress and injury induce by calcium oxalate crystals. The investigation of ethanolic extract of A. sclerocarpa leaf has shown promising antiurolithiatic activity and support folklore claims of these plants as antiurolithiatic. The mechanism of action of these plants for antiurolithiatic is apparently related to increased diuresis and lowering of urinary concentrations of stone-forming constituents, though it should be confirmed by the extensive exploratory studies
A RARE CASE OF SPACE OCCUPYING LESION OF BRAINSTEM IN AN ELDERLY MALE PATIENT
An elderly male patient aged 65 presented to us with history of swaying towards left side of the body since 1 month with normal higher mental functions and neurological examination suggestive of cerebellar ataxia. MRI Brain plus contrast was suggestive of an irregular, ill-defined heterogeneous enhancing lesion with few necrotic areas within and few foci of blooming on FFE (Fast Field Echo imaging technique) with significant perilesional oedema involving right thalamus and brainstem showing Choline peak on MR Spectroscopy.
Keywords: Neurological examination; Cerebellar ataxia; MRI brain; FFE
A RARE CASE OF SPACE OCCUPYING LESION OF BRAINSTEM IN AN ELDERLY MALE PATIENT
An elderly male patient aged 65 presented to us with history of swaying towards left side of the body since 1 month with normal higher mental functions and neurological examination suggestive of cerebellar ataxia. MRI Brain plus contrast was suggestive of an irregular, ill-defined heterogeneous enhancing lesion with few necrotic areas within and few foci of blooming on FFE (Fast Field Echo imaging technique) with significant perilesional oedema involving right thalamus and brainstem showing Choline peak on MR Spectroscopy.
Keywords: Neurological examination; Cerebellar ataxia; MRI brain; FFE
Nanoscale fluid flows in the vicinity of patterned surfaces
Molecular dynamics simulations of dense and rarefied fluids comprising small
chain molecules in chemically patterned nano-channels predict a novel switching
from Poiseuille to plug flow along the channel. We also demonstrate behavior
akin to the lotus effect for a nanodrop on a chemically patterned substrate.
Our results show that one can control and exploit the behavior of fluids at the
nanoscale using chemical patterning.Comment: Phys. Rev. Lett. in pres
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