1,026 research outputs found
Analysing the sustainability of the physical rehabilitation sector in seven fragile countries through multi-stakeholder involvement using a participatory consensus tool
Background: Sustainability is identified by nearly all organisations working in global health as one of the key indicators for project evaluation. Though typically recognised as an essential component for good project management to ensure positive impact, it is rarely applied effectively in practical terms and there are very few practical methods or tools to support implementation and monitoring of sustainable interventions. Further, despite efforts of stakeholders at all levels, the rehabilitation sector is not usually at the top of policy-makers’ agendas, which often results in limited to no funding and makes the task of building sustainability even more challenging at field level
Recoiling from a kick in the head-on collision of spinning black holes
Recoil ``kicks'' induced by gravitational radiation are expected in the
inspiral and merger of black holes. Recently the numerical relativity community
has begun to measure the significant kicks found when both unequal masses and
spins are considered. Because understanding the cause and magnitude of each
component of this kick may be complicated in inspiral simulations, we consider
these effects in the context of a simple test problem. We study recoils from
collisions of binaries with initially head-on trajectories, starting with the
simplest case of equal masses with no spin and then adding spin and varying the
mass ratio, both separately and jointly. We find spin-induced recoils to be
significant relative to unequal-mass recoils even in head-on configurations.
Additionally, it appears that the scaling of transverse kicks with spins is
consistent with post-Newtonian theory, even though the kick is generated in the
nonlinear merger interaction, where post-Newtonian theory should not apply.
This suggests that a simple heuristic description might be effective in the
estimation of spin-kicks.Comment: 12 pages, 10 figures. Replaced with published version, including more
discussion of convergence and properties of final hol
The Anisotropic Distribution of M 31 Satellite Galaxies: A Polar Great Plane of Early-Type Companions
The highly anisotropic distribution and apparent alignment of the Galactic
satellites in polar great planes begs the question how common such
distributions are. The satellite system of M31 is the only nearby system for
which we currently have sufficiently accurate distances to study the
three-dimensional satellite distribution. We present the spatial distribution
of the 15 presently known M31 companions in a coordinate system centered on M31
and aligned with its disk. Through a detailed statistical analysis we show that
the full satellite sample describes a plane that is inclined by -56 deg with
respect to the poles of M31 and that has an r.m.s. height of 100 kpc. With 88%
the statistical significance of this plane is low and it is unlikely to have a
physical meaning. The great stellar stream found near Andromeda is inclined to
this plane by 7 deg. There is little evidence for a Holmberg effect. If we
confine our analysis to early-type dwarfs, we find a best-fit polar plane
within 5 deg to 7 deg from the pole of M31. This polar great plane has a
statistical significance of 99.3% and includes all dSphs (except for And II),
M32, NGC 147, and PegDIG. The r.m.s. distance of these galaxies from the polar
plane is 16 kpc. The nearby spiral M33 has a distance of only about 3 kpc from
this plane, which points toward the M81 group. We discuss the anisotropic
distribution of M31's early-type companions in the framework of three
scenarios, namely as remnants of the break-up of a larger progenitor, as tracer
of a prolate dark matter halo, and as tracer of collapse along large-scale
filaments. (Abridged)Comment: 14 pages, 5 figures, accepted for publication in the Astronomical
Journa
Progress in Lunar Laser Ranging Tests of Relativistic Gravity
Analyses of laser ranges to the Moon provide increasingly stringent limits on
any violation of the Equivalence Principle (EP); they also enable several very
accurate tests of relativistic gravity. We report the results of our recent
analysis of Lunar Laser Ranging (LLR) data giving an EP test of \Delta
(M_G/M_I)_{EP} =(-1.0 +/- 1.4) x 10^{-13}. This result yields a Strong
Equivalence Principle (SEP) test of \Delta (M_G/M_I)_{SEP} =(-2.0 +/- 2.0) x
10^{-13}. Also, the corresponding SEP violation parameter \eta is (4.4 +/- 4.5)
x 10^{-4}, where \eta=4\beta-\gamma-3 and both \beta and \gamma are
parametrized post-Newtonian (PPN) parameters. Using the recent Cassini result
for the parameter \gamma, PPN parameter \beta is determined to be \beta-1=(1.2
+/- 1.1) x 10^{-4}. The geodetic precession test, expressed as a relative
deviation from general relativity, is K_{gp}=-0.0019 +/- 0.0064. The search for
a time variation in the gravitational constant results in \dot G/G=(4 +/- 9) x
10^{-13} yr^{-1}, consequently there is no evidence for local (~1AU) scale
expansion of the solar system.Comment: 4 pages, revtex4, minor changes made for publicatio
Is copyright blind to the visual?
This article argues that, with respect to the copyright protection of works of visual art, the general uneasiness that has always pervaded the relationship between copyright law and concepts of creativity produces three anomalous results. One of these is that copyright lacks much in the way of a central concept of 'visual art' and, to the extent that it embraces any concept of the 'visual', it is rooted in the rhetorical discourse of the Renaissance. This means that copyright is poorly equipped to deal with modern developments in the visual arts. Secondly, the pervasive effect of rhetorical discourse appears to have made it particularly difficult for copyright law to strike a meaningful balance between protecting creativity and permitting its use in further creative works. Thirdly, just when rhetorical discourse might have been useful in identifying the significance and materiality of the unique one-off work of visual art, copyright law chooses to ignore its implications
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