3,381 research outputs found
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.
Kant's philosophy of the aesthetic and the philosophy of praxis
This is the author's accepted manuscript. The final published article is available from the link below. Copyright @ 2012 Association for Economic and Social Analysis.This essay seeks to reconstruct the terms for a more productive engagement with Kant than is typical within contemporary academic cultural Marxism, which sees him as the cornerstone of a bourgeois model of the aesthetic. The essay argues that, in the Critique of Judgment, the aesthetic stands in as a substitute for the missing realm of human praxis. This argument is developed in relation to Kant's concept of reflective judgment that is in turn related to a methodological shift toward inductive and analogical procedures that help Kant overcome the dualisms of the first two Critiques. This reassessment of Kant's aesthetic is further clarified by comparing it with and offering a critique of Terry Eagleton's assessment of the Kantian aesthetic as synonymous with ideology
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
The 2.5PN linear momentum flux and associated recoil from inspiralling compact binaries in quasi-circular orbits: Nonspinning case
Anisotropic emission of gravitational waves (GWs) from inspiralling compact
binaries leads to the loss of linear momentum and hence gravitational recoil of
the system. The loss rate of linear momentum in the far-zone of the source (a
nonspinning binary system of black holes in quasicircular orbit) is
investigated at the 2.5 post-Newtonian (PN) order and used to provide an
analytical expression in harmonic coordinates for the 2.5PN accurate recoil
velocity of the binary accumulated in the inspiral phase. We find that the
recoil velocity at the end of the inspiral phase (i.e at the innermost stable
circular orbit (ISCO)) is maximum for a binary with symmetric mass ratio of
\nu~0.2 and is roughly about ~4.58 km/s. Going beyond inspiral, we also provide
an estimate of the more important contribution to the recoil velocity from the
plunge phase. Again the recoil velocity at the end of the plunge, involving
contributions both from inspiral and plunge phase, is maximum for a binary with
\nu~0.2 and is of the order of ~180 km/s.Comment: 17 pages, 1 figure; This version includes the changes appearing in
the Erratum published in Phys. Rev.
Synchrotron x-ray study of lattice vibrations in CdCr2O4
Using inelastic x-ray scattering we have investigated lattice vibrations in a
geometric frustrated system CdCr2O4 that upon cooling undergoes a spin-Peierls
phase transition at TN = 7.8 K from a cubic and paramagnetic to a tetragonal
and Neel state. Phonon modes measured around Brillouin zone boundaries show
energy shifts when the transition occurs. Our analysis shows that the shifting
can be understood as the ordinary effects of the lowering of the crystal
symmetry
Kwanu Local – A High Yielding Traditional Maize Cultivar of Jaunsar Tribal Region of Uttarakhand and a Promising Genetic Resource for Maize Improvement
Globally maize is the second most important crop in terms of acreage where as in India it ranks third after wheat and rice. Maize productivity has been breaking unprecedented barriers owing chiefly to wide scale cultivation of high yielding hybrids. Sustaining high yields of hybrids necessitates continued efforts for creation of novel gene assemblages and/or discovery of such naturally existing constellations. Traditional local cultivars are an important source of the latter. Kwanu Local is an example of such a traditional cultivar that contributes significantly towards sustaining food, fodder and fuel requirement of Jaunsari tribal community of Kwanu cluster in Dehradun district of Uttarakhand. It is a tall, high yielding, medium duration, semi-dent yellow bold-grained cultivar and owes its characteristic present form to multiple infusions from diverse populations that have taken place over the long history of its cultivation in the region. Its cultivation over a vast contiguous expanse and the selection practices followed by the farming community ensure maintenance of high heterozygosity in the population, assuring sustained high yields. The cultivar possesses many desirable features that make it a potential genetic resource for a variety of traits of agronomic importance (cob length, cob girth, number of kernels/row and kernel size). Its use for increasing kernel size has been well demonstrated. Kernel size in the backcross progenies involving inbreds VQL 1 (255 g) and V 400 (215 g) as recipients and Kwanu Local (343 g) as donor exhibited kernel size range of 260-293 g (VQL 1 x Kwanu Local) and 228-245 g (V 400 x Kwanu Local), showing increase of 6-14 and 2-15%, respectively, in the two crosses. With its local adaptability and high yield coupled with other desirable traits, Kwanu Local holds potential as a promising genetic resource for maize improvement
A functional-cognitive framework for attitude research
In attitude research, behaviours are often used as proxies for attitudes and attitudinal processes. This practice is problematic because it conflates the behaviours that need to be explained (explanandum) with the mental constructs that are used to explain these behaviours (explanans). In the current chapter we propose a meta-theoretical framework that resolves this problem by distinguishing between two levels of analysis. According to the proposed framework, attitude research can be conceptualised as the scientific study of evaluation. Evaluation is defined not in terms of mental constructs but in terms of elements in the environment, more specifically, as the effect of stimuli on evaluative responses. From this perspective, attitude research provides answers to two questions: (1) Which elements in the environment moderate evaluation? (2) What mental processes and representations mediate evaluation? Research on the first question provides explanations of evaluative responses in terms of elements in the environment (functional level of analysis); research on the second question offers explanations of evaluation in terms of mental processes and representations (cognitive level of analysis). These two levels of analysis are mutually supportive, in that better explanations at one level lead to better explanations at the other level. However, their mutually supportive relation requires a clear distinction between the concepts of their explanans and explanandum, which are conflated if behaviours are treated as proxies for mental constructs. The value of this functional-cognitive framework is illustrated by applying it to four central questions of attitude research
Electron and hole transmission through superconductor - normal metal interfaces
We have investigated the transmission of electrons and holes through
interfaces between superconducting aluminum (Tc = 1.2 K) and various normal
non-magnetic metals (copper, gold, palladium, platinum, and silver) using
Andreev-reflection spectroscopy at T = 0.1 K. We analyzed the point contacts
with the modified BTK theory that includes Dynes' lifetime as a fitting
parameter G in addition to superconducting energy gap 2D and normal reflection
described by Z. For contact areas from 1 nm^2 to 10000 nm^2 the BTK Z parameter
was 0.5, corresponding to transmission coefficients of about 80 %, independent
of the normal metal. The very small variation of Z indicates that the
interfaces have a negligible dielectric tunneling barrier. Fermi surface
mismatch does not account for the observed transmission coefficient.Comment: 9 pages, 4 figures, submitted to Proceedings of the 19th
International Conference on Magnetism ICM2012 (Busan 2012
Axial-flexural coupled vibration and buckling of composite beams using sinusoidal shear deformation theory
A finite element model based on sinusoidal shear deformation theory is developed to study vibration and buckling analysis of composite beams with arbitrary lay-ups. This theory satisfies the zero traction boundary conditions on the top and bottom surfaces of beam without using shear correction factors. Besides, it has strong similarity with Euler–Bernoulli beam theory in some aspects such as governing equations, boundary conditions, and stress resultant expressions. By using Hamilton’s principle, governing equations of motion are derived. A displacement-based one-dimensional finite element model is developed to solve the problem. Numerical results for cross-ply and angle-ply composite beams are obtained as special cases and are compared with other solutions available in the literature. A variety of parametric studies are conducted to demonstrate the effect of fiber orientation and modulus ratio on the natural frequencies, critical buckling loads, and load-frequency curves as well as corresponding mode shapes of composite beams
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