2,245 research outputs found
Greybody factor of scalar fields from black strings
The greybody factor of massless, uncharged scalar fields is studied in the
background of cylindrically symmetric spacetimes, in the low-energy
approximation. We discuss two cases. In the first case we derive analytical
expression for the absorption probability when the spacetime is kinetically
coupled with the Einstein tensor. In the second case we do the analysis in the
absence of the coupling constant. For this purpose we analyze the wave equation
which is obtained from Klein-Gordon equation. The radial part of the wave
equation is solved in the form of the hypergeometric function in the near
horizon region, whereas in the far region the solution is of the form of
Bessel's function. Finally, considering continuity of the wave function we
smoothly match the two solutions in the low energy approximation to get the
formula for the absorption probability
Greybody factor of scalar field from Reissner-Nordstrom-de Sitter black hole
In this work we derive a general expression for the greybody factor of
non-minimally coupled scalar fields in Reissner-Nordstr\"om-de Sitter spacetime
in low frequency approximation. In particular case of zero momentum, greybody
factor tends to zero in low frequency limit as frequency squared goes to zero
for non-vanishing coupling. We also elaborate the significance of the results
by giving formulae of differential energy rate and general absorption cross
section. The greybody factor gives insight into the spectrum of Hawking
radiations
Attractor Solutions in f(T) Cosmology
In this paper, we explore the cosmological implications of interacting dark
energy model in a torsion based gravity namely . Assuming dark energy
interacts with dark matter and radiation components, we examine the stability
of this model by choosing different forms of interaction terms. We consider
three different forms of dark energy: cosmological constant, quintessence and
phantom energy. We then obtain several attractor solutions for each dark energy
model interacting with other components. This model successfully explains the
coincidence problem via the interacting dark energy scenario.Comment: 10 pages, 23 figures, version accepted for publication in European
Physical Journal C (2012
Chemical constituents of the fruit and hypocotyl of mangrove, Ceriops tagal
The fruit and hypocotyl of Ceriops tagal were analysed for their organic and inorganic constituents. They showed almost similar characteristics in major metabolites and high molecular weight elements. Both the samples had high concentration of the carbohydrates and crude fibre and very low in fat and protein. The ash was rich in NA, K and Ca. Some essential free amino acids and sugars were also present. Calorific values were found fairly high. There is a strong possibility of using fruit and hypocotyl of C. tagal as a source for supplementing animal feed
Transcriptional factor PU.1 regulates decidual C1q expression in early pregnancy in human
"Copyright: © 2015 Madhukaran, Kishore, Jamil, Teo, Choolani and Lu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms."C1q is the first recognition subcomponent of the complement classical pathway, which in addition to being synthesized in the liver, is also expressed by macrophages and dendritic cells (DCs). Trophoblast invasion during early placentation results in accumulation of debris that triggers the complement system. Hence, both early and late components of the classical pathway are widely distributed in the placenta and decidua. In addition, C1q has recently been shown to significantly contribute to feto-maternal tolerance, trophoblast migration, and spiral artery remodeling, although the exact mechanism remains unknown. Pregnancy in mice, genetically deficient in C1q, mirrors symptoms similar to that of human preeclampsia. Thus, regulated complement activation has been proposed as an essential requirement for normal successful pregnancy. Little is known about the molecular pathways that regulate C1q expression in pregnancy. PU.1, an Ets-family transcription factor, is required for the development of hematopoietic myeloid lineage immune cells, and its expression is tissue-specific. Recently, PU.1 has been shown to regulate C1q gene expression in DCs and macrophages. Here, we have examined if PU.1 transcription factor regulates decidual C1q expression. We used immune-histochemical analysis, PCR, and immunostaining to localize and study the gene expression of PU.1 transcription factor in early human decidua. PU.1 was highly expressed at gene and protein level in early human decidual cells including trophoblast and stromal cells. Surprisingly, nuclear as well as cytoplasmic PU.1 expression was observed. Decidual cells with predominantly nuclear PU.1 expression had higher C1q expression. It is likely that nuclear and cytoplasmic PU.1 localization has a role to play in early pregnancy via regulating C1q expression in the decidua during implantation
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