1,648 research outputs found
An effectual template bank for the detection of gravitational waves from inspiralling compact binaries with generic spins
We report the construction of a three-dimensional template bank for the
search for gravitational waves from inspiralling binaries consisting of
spinning compact objects. The parameter space consists of two dimensions
describing the mass parameters and one "reduced-spin" parameter, which
describes the secular (non-precessing) spin effects in the waveform. The
template placement is based on an efficient stochastic algorithm and makes use
of the semi-analytical computation of a metric in the parameter space. We
demonstrate that for "low-mass" () binaries,
this template bank achieves effective fitting factors --
towards signals from generic spinning binaries in the advanced detector era
over the entire parameter space of interest (including binary neutron stars,
binary black holes, and black hole-neutron star binaries). This provides a
powerful and viable method for searching for gravitational waves from generic
spinning low-mass compact binaries. Under the assumption that spin magnitudes
of black-holes [neutron-stars] are uniformly distributed between 0--0.98 [0 --
0.4] and spin angles are isotropically distributed, the expected improvement in
the average detection volume (at a fixed signal-to-noise-ratio threshold) of a
search using this reduced-spin bank is , as compared to a search
using a non-spinning bank.Comment: Minor changes, version appeared in Phys. Rev.
Validity of the Generalized Second Law of Thermodynamics of the Universe Bounded by the Event Horizon in Brane Scenario
In this paper, we examine the validity of the generalized second law of
thermodynamics (GSLT) of the universe bounded by the event horizon in
brane-world gravity. Here we consider homogeneous and isotropic model of the
universe filled with perfect fluid in one case and in another case holographic
dark energy model of the universe has been considered. The conclusions are
presented point wise.Comment: 8 pages, the paper has been accepted in EPJC for publication.
Conclusion has been modified an some references have been adde
Dirac electrons in the presence of matrix potential barrier: application to graphene and topological insulators
Scattering of a 2D Dirac electrons on a rectangular matrix potential barrier
is considered using the formalism of spinor transfer matrices. It is shown, in
particular, that in the absence of the mass term, the Klein tunneling is not
necessarily suppressed but occurs at oblique incidence. The formalism is
applied to studying waveguiding modes of the barrier, which are supported by
the edge and bulk states. The condition of existence of the uni-directionality
property is found. We show that the band of edge states is always finite with
massless excitations, while the spectrum of the bulk states, depending on
parameters of the barrier, may consist of the infinite or finite band with
both, massive and massless, low-energy excitations. The effect of the Zeeman
term is considered and the condition of appearance of two distinct energy
dependent directions corresponding to the Klein tunneling is found.Comment: published versio
Bimetallic Cooperativity in Proton Reduction with an Amido‐Bridged Cobalt Catalyst
The bimetallic catalyst [CoII2(L1)(bpy)2]ClO4 (1), in which L1 is an [NN′2O2] fused ligand, efficiently reduced H+ to H2 in CH3CN in the presence of 100 equiv of HOAc with a turnover number of 18 and a Faradaic efficiency of 94 % after 3 h of bulk electrolysis at −1.6 V (vs. Ag/AgCl). This observation allowed the proposal that this bimetallic cooperativity is associated with distance, angle, and orbital alignment of the two Co centers, as promoted by the unique Co−Namido−Co environment offered by L1. Experimental results revealed that the parent [CoIICoII] complex undergoes two successive metal‐based 1 e− reductions to generate the catalytically active species [CoICoI], and DFT calculations suggested that addition of a proton to one CoI triggers a cooperative 1 e− transfer by each of these CoI centers. This 2 e− transfer is an alternative route to generate a more reactive [CoII(CoII−H−)] hydride, thus avoiding the CoIII−H− required in monometallic species. This [CoII(CoII−H−)] species then accepts another H+ to release H2
The Effect of Convection on Disorder in Primary Cellular and Dendritic Arrays
Directional solidification studies have been carried out to characterize the spatial disorder in the arrays of cells and dendrites. Different factors that cause array disorder are investigated experimentally and analyzed numerically. In addition to the disorder resulting from the fundamental selection of a range of primary spacings under given experimental conditions, a significant variation in primary spacings is shown to occur in bulk samples due to convection effects, especially at low growth velocities. The effect of convection on array disorder is examined through directional solidification studies in two different alloy systems, Pb-Sn and Al-Cu. A detailed analysis of the spacing distribution is carried out, which shows that the disorder in the spacing distribution is greater in the Al-Cu system than in Pb-Sn system. Numerical models are developed which show that fluid motion can occur in both these systems due to the negative axial density gradient or due the radial temperature gradient which is always present in Bridgman growth. The modes of convection have been found to be significantly different in these systems, due to the solute being heavier than the solvent in the Al-Cu system and lighter than it in the Pb-Sn system. The results of the model have been shown to explain experimental observations of higher disorder and greater solute segregation in a weakly convective Al-Cu system than those in a highly convective Pb-Sn system
Anti-Inflammatory Potential of Ethanolic Leaf Extract of Eupatorium adenophorum Spreng. Through Alteration in Production of TNF-α, ROS and Expression of Certain Genes
Search for a novel anti-inflammatory agent from a herbal source, such as Eupatorium adenophorum Spreng., a plant from the Eastern Himalayas, is of prime interest in the present investigation. Inflammation causes tissue destruction and development of diseases such as asthma, rheumatoid arthritis, and so forth. The ethanolic leaf extract of E. adenophorum (EEA) was administered intravenously and in other cases topically at the site of delayed type hypersensitivity (DTH) reaction in mouse foot paw induced with dinitrofluorobenzene. EEA can effectively inhibit DTH reaction and bring back normalcy to the paw much earlier than the controls. Efficacy of EEA on regulatory mechanisms for inflammation has also been considered. Intravenous administration of EEA increased the number of CD4+ T cells in spleen and tumor necrosis factor (TNF)-α in serum of DTH mice. Initially it was difficult to reconcile with the anti-inflammatory role of EEA and simultaneous induction of TNF-α, an established pro-inflammatory cytokine. EEA induces higher expression of TNF-α gene and amount of the cytokine in serum. We discussed the other role of TNF-α, its involvement in repairing tissue damage incurred in course of inflammatory reaction. EEA also induces TGF-β encoding a cytokine involved in tissue repair mechanism. EEA inhibits expression of another pro-inflammatory cytokine gene IL-1β and downregulates cycloxygenase 2 (COX2) gene responsible for metabolism of inflammatory mediators like prostaglandins. Furthermore, anti-inflammatory role of EEA is also revealed through its inhibition of hydroxyl radical generation. Notably EEA does not necessarily affect the expression of other inflammation-related genes such as IL-6, IL-10 and IKK. The present study reports and analyzes for the first time the anti-inflammatory property of the leaf extract of E. adenophorum
Scalar-Tensor Theory of Gravity and Generalized Second Law of Thermodynamics on the Event Horizon
In blackhole physics, the second law of thermodynamics is generally valid
whether the blackhole is a static or a non-static one. Considering the universe
as a thermodynamical system the second law of blackhole dynamics extends to the
non-negativity of the sum of the entropy of the matter and the horizon, known
as generalized second law of thermodynamics(GSLT). Here, we have assumed the
universe to be bounded by the event-horizon or filled with perfect fluid and
holographic dark energy in two cases. Thus considering entropy to be an
arbitrary function of the area of the event-horizon, we have tried to find the
conditions and the restrictions over the scalar field and equation of state for
the validity of the GSLT and both in quintessence-era and in phantom-era in
scalar tensor theory.Comment: 8 page
Typhus Fever: An Overlooked Diagnosis
A case of typhus fever is presented. On admission, the clinical diagnosis was typhoid fever. Forty-eight hours after admission, the presence of subconjunctival haemorrhage, malena, and jaundice raised the possibility of a different aetiology, the two most likely differentials being dengue and typhus. Finally, a co-infection of typhoid and typhus was discovered. This uncommon clinical scenario should be taken into account in the management of patients with high fever on admission being treated as a case of typhoid fever
Quenching of light hadrons at RHIC in a collisional energy loss scenario
We evaluate the nuclear suppression factor, for light hadrons
by taking into account the collisional energy loss. We show that in the
measured domain of RHIC the elastic process is the dominant mechanism for
the partonic energy loss.Comment: 4 pages with 3 figures, Quark Matter 2008 Proceeding
Aspects of meson properties in dense nuclear matter
We investigate the modification of meson spectral densities in dense nuclear
matter at zero temperature. These effects are studied in a fully relativistic
mean field model which goes beyond the linear density approximation and also
includes baryon resonances. In particular, the role of N*(1520) and N*(1720) on
the rho meson spectral density is highlighted. Even though the nucleon-nucleon
loop and the nucleon-resonance loop contribute with the opposite sign, an
overall reduction of rho meson mass is still observed at high density.
Importantly, it is shown that the resonances cause substantial broadening of
the rho meson spectral density in matter and also induces non-trivial momentum
dependence. The spectral density of the a0 meson is also shown. We study the
dispersion relations and collective oscillations induced by the rho meson
propagation in nuclear matter together with the influence of the mixing of rho
with the a0 meson. The relevant expression for the plasma frequency is also
recovered analytically in the appropriate limit.Comment: 19 pages, 17 figure
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