33,785 research outputs found
Valuing the voluntary sector: rethinking economic analysis
The voluntary sector plays an important role in the sports industry, as a provider of sporting opportunities and in the development of sport, from increasing participation through to supporting excellence and elite performance. However, despite this importance, research on its contribution to sport-related economic activity is limited, with information on this sector remaining the weakest part of current economic assessments of the UK sports industry. The research presented in this article examines the economic importance of the voluntary sector, using a case study of Sheffield. It demonstrates that the sports voluntary sector in the city is considerably smaller than was predicted when using national estimates, and that this is largely a consequence of methodological issues relating to previous research. The article suggests that in the light of the findings and the increasing use of sport in urban policy, there is a need to rethink the methodology used to evaluate the economic contribution of the voluntary sector in the future.</p
The quenching of star formation in accretion-driven clumpy turbulent tori of active galactic nuclei
Galactic gas-gas collisions involving a turbulent multiphase ISM share common
ISM properties: dense extraplanar gas visible in CO, large linewidths (>= 50
km/s), strong mid-infrared H_2 line emission, low star formation activity, and
strong radio continuum emission. Gas-gas collisions can occur in the form of
ICM ram pressure stripping, galaxy head-on collisions, compression of the
intragroup gas and/or galaxy ISM by an intruder galaxy which flies through the
galaxy group at a high velocity, or external gas accretion on an existing gas
torus in a galactic center. We suggest that the common theme of all these
gas-gas interactions is adiabatic compression of the ISM leading to an increase
of the turbulent velocity dispersion of the gas. The turbulent gas clouds are
then overpressured and star formation is quenched. Within this scenario we
developed a model for turbulent clumpy gas disks where the energy to drive
turbulence is supplied by external infall or the gain of potential energy by
radial gas accretion within the disk. The cloud size is determined by the size
of a C-type shock propagating in dense molecular clouds with a low ionization
fraction at a given velocity dispersion. We give expressions for the expected
volume and area filling factors, mass, density, column density, and velocity
dispersion of the clouds. The latter is based on scaling relations of
intermittent turbulence whose open parameters are estimated for the CND in the
Galactic Center. The properties of the model gas clouds and the external mass
accretion rate necessary for the quenching of the star formation rate due to
adiabatic compression are consistent with those derived from high-resolution
H_2 line observations. Based on these findings, a scenario for the evolution of
gas tori in galactic centers is proposed and the implications for star
formation in the Galactic Center are discussed.Comment: 13 pages, 1 figure, accepted for publication by A&
Evolutionary origins of ultrasonic hearing and laryngeal echolocation in bats inferred from morphological analyses of the inner ear
PMCID: PMC3598973This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited
Spectral Stability of the Neumann Laplacian
We prove the equivalence of Hardy- and Sobolev-type inequalities, certain
uniform bounds on the heat kernel and some spectral regularity properties of
the Neumann Laplacian associated with an arbitrary region of finite measure in
Euclidean space. We also prove that if one perturbs the boundary of the region
within a uniform H\"older category then the eigenvalues of the Neumann
Laplacian change by a small and explicitly estimated amount.
AMS subject classifications: 35P15, 35J25, 47A75, 47B25, 26D10, 46E35.
Keywords: Neumann Laplacian, Sobolev inequalities, Hardy inequalities,
spectral stability, H\"older continuity.Comment: 23 page
Flame: A Flexible Data Reduction Pipeline for Near-Infrared and Optical Spectroscopy
We present flame, a pipeline for reducing spectroscopic observations obtained
with multi-slit near-infrared and optical instruments. Because of its flexible
design, flame can be easily applied to data obtained with a wide variety of
spectrographs. The flexibility is due to a modular architecture, which allows
changes and customizations to the pipeline, and relegates the
instrument-specific parts to a single module. At the core of the data reduction
is the transformation from observed pixel coordinates (x, y) to rectified
coordinates (lambda, gamma). This transformation consists in the polynomial
functions lambda(x,y) and gamma(x,y) that are derived from arc or sky emission
lines and slit edge tracing, respectively. The use of 2D transformations allows
one to wavelength calibrate and rectify the data using just one interpolation
step. Furthermore, the gamma(x,y) transformation includes also the spatial
misalignment between frames, which can be measured from a reference star
observed simultaneously with the science targets. The misalignment can then be
fully corrected during the rectification, without having to further resample
the data. Sky subtraction can be performed via nodding and/or modeling of the
sky spectrum; the combination of the two methods typically yields the best
results. We illustrate the pipeline by showing examples of data reduction for a
near-infrared instrument (LUCI at the Large Binocular Telescope) and an optical
one (LRIS at the Keck telescope).Comment: 17 pages, 10 figures, published in MNRAS. The pipeline is available
at https://github.com/siriobelli/flam
Dust Emissivity in the Far-Infrared
We have derived the dust emissivity in the Far-Infrared (FIR) using data
available in the literature. We use two wavelength dependences derived from
spectra of Galactic FIR emission (Reach et al. 1995). A value for the
emissivity, normalised to the extinction efficiency in the V band, has been
retrieved from maps of Galactic FIR emission, dust temperature and extinction
(Schlegel et al. 1998).
Our results are similar to other measurements in the Galaxy but only
marginally consistent with the widely quoted values of Hildebrand (1983)
derived on one reflection nebula. The discrepancy with measurements on other
reflection nebulae (Casey 1991) is higher and suggests a different grain
composition in these environments with respect to the diffuse interstellar
medium.
We measure dust masses for a sample of six spiral galaxies with FIR
observations and obtain gas-to-dust ratios close to the Galactic value.Comment: 5 pages, 1 ps file, A&A letter accepte
Condensation risk: comparison of steady-state and transient methods
Accurate assessment of both surface and interstitial condensation risk is important not only to reduce the damaging effect of moisture within the structure of buildings, but also to provide a healthy environment free from mould growth. The current British Standard (BS EN ISO 13788: 2002) contains an assessment procedure based on the assumption of a steady-state heat flow through the building envelope, neglecting the transient nature of the problem. This paper compares and evaluates numerical results of the condensation risk calculation under both steady-state and transient conditions using the existing numerical codes. Significant differences are apparent between the predictions of the simple (steady-state) and complex (transient) methods for all construction details modelled
Star Formation and Dynamics in the nuclei of AGN
Using adaptive optics on Keck and the VLT in the H- and K-bands, we have
begun a project to probe the dynamics and star formation around AGN on scales
of 0.1arcsec. The stellar content of the nucleus is traced through the
2.29micron CO2-0 and 1.62micron CO6-3 absorption bandheads. These features are
directly spatially resolved, allowing us to measure the extent and distribution
of the nuclear star forming region. The dynamics are traced through the
2.12micron H_2 1-0S(1) and 1.64micron [FeII] emission lines, as well as stellar
absorption features. Matching disk models to the rotation curves at various
position angles allows us to determine the mass of the stellar and gas
components, and constrain the mass of the central black hole. In this
contribution we summarise results for the two type~1 AGN Mkn231 and NGC7469.Comment: contribution to "The interplay among Black Holes, Stars and ISM in
Galactic Nuclei", March 200
How effective is harassment on infalling late-type dwarfs?
A new harassment model is presented that models the complex, and dynamical
tidal field of a Virgo like galaxy cluster. The model is applied to small,
late-type dwarf disc galaxies (of substantially lower mass than in previous
harassment simulations) as they infall into the cluster from the outskirts.
These dwarf galaxies are only mildly affected by high speed tidal encounters
with little or no observable consequences; typical stellar losses are ,
producing very low surface brightness streams ( mag arcsec),
and a factor of two drop in dynamical mass-to-light ratio. Final stellar discs
remain disc-like, and dominated by rotation although often with tidally induced
spiral structure. By means of Monte-Carlo simulations, the statistically likely
influences of harassment on infalling dwarf galaxies are determined. The
effects of harassment are found to be highly dependent on the orbit of the
galaxy within the cluster, such that newly accreted dwarf galaxies typically
suffer only mild harassment. Strong tidal encounters, that can morphologically
transform discs into spheroidals, are rare occurring in of dwarf
galaxy infalls for typical orbits of sub-structure within CDM cluster
mass halos. For orbits with small apocentric distances (250 kpc), harassment
is significantly stronger resulting in complete disruption or heavy mass loss
( dark matter and stellar), however, such orbits are expected
to be highly improbable for newly infalling galaxies due to the deep potential
well of the cluster.Comment: 15 pages, 11 figures, 4 table
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