3,956 research outputs found
Higher signal harmonics, LISA's angular resolution, and dark energy
It is generally believed that the angular resolution of the Laser
Interferometer Space Antenna (LISA) for binary supermassive black holes (SMBH)
will not be good enough to identify the host galaxy or galaxy cluster. This
conclusion, based on using only the dominant harmonic of the binary SMBH
signal, changes substantially when higher signal harmonics are included in
assessing the parameter estimation problem. We show that in a subset of the
source parameter space the angular resolution increases by more than a factor
of 10, thereby making it possible for LISA to identify the host galaxy/galaxy
cluster. Thus, LISA's observation of certain binary SMBH coalescence events
could constrain the dark energy equation of state to within a few percent,
comparable to the level expected from other dark energy missions.Comment: 15 pages, no figures. Final version to appear in Phys. Rev.
Quantification of yield gaps in rain-fed rice, wheat, cotton and mustard in India
Rainfed farming / Crop yield / Simulation / Rice / Wheat / Cotton / Mustard / India
Head-on infall of two compact objects: Third post-Newtonian Energy Flux
Head-on infall of two compact objects with arbitrary mass ratio is
investigated using the multipolar post-Minkowskian approximation method. At the
third post-Newtonian order the energy flux, in addition to the instantaneous
contributions, also includes hereditary contributions consisting of the
gravitational-wave tails, tails-of-tails and the tail-squared terms. The
results are given both for infall from infinity and also for infall from a
finite distance. These analytical expressions should be useful for the
comparison with the high accuracy numerical relativity results within the limit
in which post-Newtonian approximations are valid.Comment: 25 pages, 2 figures, This version includes the changes appearing in
the Erratum published in Phys. Rev.
Comparison of post-Newtonian templates for compact binary inspiral signals in gravitational-wave detectors
The two-body dynamics in general relativity has been solved perturbatively
using the post-Newtonian (PN) approximation. The evolution of the orbital phase
and the emitted gravitational radiation are now known to a rather high order up
to O(v^8), v being the characteristic velocity of the binary. The orbital
evolution, however, cannot be specified uniquely due to the inherent freedom in
the choice of parameter used in the PN expansion as well as the method pursued
in solving the relevant differential equations. The goal of this paper is to
determine the (dis)agreement between different PN waveform families in the
context of initial and advanced gravitational-wave detectors. The waveforms
employed in our analysis are those that are currently used by Initial
LIGO/Virgo, that is the time-domain PN models TaylorT1, TaylorT2, TaylorT3,
TaylorT4 and TaylorEt, the effective one-body (EOB) model, and the
Fourier-domain representation TaylorF2. We examine the overlaps of these models
with one another and with the prototype effective one-body model (calibrated to
numerical relativity simulations, as currently used by initial LIGO) for a
number of different binaries at 2PN, 3PN and 3.5PN orders to quantify their
differences and to help us decide whether there exist preferred families that
are the most appropriate as search templates. We conclude that as long as the
total mass remains less than a certain upper limit M_crit, all template
families at 3.5PN order (except TaylorT3 and TaylorEt) are equally good for the
purpose of detection. The value of M_crit is found to be ~ 12M_Sun for Initial,
Enhanced and Advanced LIGO. From a purely computational point of view we
recommend that 3.5PN TaylorF2 be used below Mcrit and EOB calibrated to
numerical relativity simulations be used for total binary mass M > Mcrit.Comment: 27 pages, 8 figures, 4 tables, submitted to PR
Investigations of linear and nonlinear optical properties of transparent ZnO thin films grown by sol-gel method
Always Better Control-Vital Essential Desirable analysis of the drugs used in health centres of Ahmedabad district
Background: The basic principle of inventory control is Always Better Control (ABC) based on cost criteria and Vital Essential Desirable (VED) on criticality. Inequity in drug prioritization and expenses directly affects the health of the community. Study design: Based on ABC-VED matrix, inventory analysis was done. Study area: Community health centre (CHC) - Singarva, two primary health centres (PHC) - Kanbha and Sanathal and two urban health centre (UHC) - Amraiwadi and Sabarmati. Study period: December 2012 to December 2013.Methods: The drugs were first categorized by ABC method and then by VED method. On coupling the two techniques, ABC-VED matrix was made and drugs were classified in to Category I (AV + BV +CV + AE + AD), Category II (BE + CE + BD) and Category III (CD).Results: According to VED analysis large amount of money was spent on D category that is; 35% of annual drug expenditure (ADE) from CHC, 7.6% and 23.4% from both the PHC respectively, 20.1% and 24.7% from both the UHCs. On considering the ABC-VED matrix analysis the ADE spent on Class III was 6.6% among CHC, 1.2% and 1.5% among PHC, 2.6% and 7.2% among the UHC.Conclusion: The ADE used among the ABC-VED Class III should be avoided and the ADE on Class II drugs should be controlled and used judiciously
Parametrized tests of post-Newtonian theory using Advanced LIGO and Einstein Telescope
General relativity has very specific predictions for the gravitational
waveforms from inspiralling compact binaries obtained using the post-Newtonian
(PN) approximation. We investigate the extent to which the measurement of the
PN coefficients, possible with the second generation gravitationalwave
detectors such as the Advanced Laser Interferometer Gravitational-Wave
Observatory (LIGO) and the third generation gravitational-wave detectors such
as the Einstein Telescope (ET), could be used to test post-Newtonian theory and
to put bounds on a subclass of parametrized-post-Einstein theories which differ
from general relativity in a parametrized sense. We demonstrate this
possibility by employing the best inspiralling waveform model for nonspinning
compact binaries which is 3.5PN accurate in phase and 3PN in amplitude. Within
the class of theories considered, Advanced LIGO can test the theory at 1.5PN
and thus the leading tail term. Future observations of stellar mass black hole
binaries by ET can test the consistency between the various PN coefficients in
the gravitational-wave phasing over the mass range of 11-44 Msun. The choice of
the lower frequency cut off is important for testing post-Newtonian theory
using the ET. The bias in the test arising from the assumption of nonspinning
binaries is indicated.Comment: 18 pages, 11 figures, Matches with the published versio
Foam-based synthesis of cobalt nanoparticles and their subsequent conversion to Co<SUB>core</SUB>Ag<SUB>shell</SUB> nanoparticles by a simple transmetallation reaction
Cobalt nanoparticles have been synthesized via a novel, foam-based protocol. The foam is formed from an aqueous mixture of Co2+ ions, an anionic surfactant and oleic acid where the cobalt ions are electrostatically entrapped by the surfactant at the thin borders between the foam bubbles and their junctions. The entrapped cobalt ions may be reduced in-situ by a moderately strong reducing agent resulting in the formation of nanoparticles with the foam playing the role of a template. The nanoparticles are immediately capped and stabilized against oxidation by oleic acid present in the foam matrix. The oleic acid-capped Co nanoparticles can be redispersed either in an aqueous or organic medium making this procedure very attractive. The cobalt nanoparticles are readily converted to CocoreAgshell nanoparticles by simple addition of a silver salt to the Co nanoparticle solution, the cobalt atoms on the nanoparticle surface acting as localized reducing agents for the silver ions
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