30,333 research outputs found
Fabrication and test of lightweight honeycomb sandwich structures Final report
Fabrication and testing of lightweight honeycomb sandwich structure
Catalogue of 12CO(J=1-0) and 13CO(J=1-0) Molecular Clouds in the Carina Flare Supershell
We present a catalogue of 12CO(J=1-0) and 13CO(J=1-0) molecular clouds in the
spatio-velocity range of the Carina Flare supershell, GSH 287+04-17. The data
cover a region of ~66 square degrees and were taken with the NANTEN 4m
telescope, at spatial and velocity resolutions of 2.6' and 0.1 km/s.
Decomposition of the emission results in the identification of 156 12CO clouds
and 60 13CO clouds, for which we provide observational and physical parameters.
Previous work suggests the majority of the detected mass forms part of a
comoving molecular cloud complex that is physically associated with the
expanding shell. The cloud internal velocity dispersions, degree of
virialization and size-linewidth relations are found to be consistent with
those of other Galactic samples. However, the vertical distribution is heavily
skewed towards high-altitudes. The robust association of high-z molecular
clouds with a known supershell provides some observational backing for the
theory that expanding shells contribute to the support of a high-altitude
molecular layer.Comment: To be published in PASJ Vol. 60, No. 6. (Issued on December 25th
2008). 35 pages (including 13 pages of tables), 7 figures. Please note that
formatting problems with the journal macro result in loss of rightmost data
columns in some long tables. These will be fixed in the final published
issue. In the meantime, please contact the authors for missing dat
Geometry of Empty Space is the Key to Near-Arrest Dynamics
We study several examples of kinetically constrained lattice models using
dynamically accessible volume as an order parameter. Thereby we identify two
distinct regimes exhibiting dynamical slowing, with a sharp threshold between
them. These regimes are identified both by a new response function in
dynamically available volume, as well as directly in the dynamics. Results for
the selfdiffusion constant in terms of the connected hole density are
presented, and some evidence is given for scaling in the limit of dynamical
arrest.Comment: 11 page
The Supershell-Molecular Cloud Connection in the Milky Way and Beyond
The role of large-scale stellar feedback in the formation of molecular clouds
has been investigated observationally by examining the relationship between HI
and 12CO(J=1-0) in supershells. Detailed parsec-resolution case studies of two
Milky Way supershells demonstrate an enhanced level of molecularisation over
both objects, and hence provide the first quantitative observational evidence
of increased molecular cloud production in volumes of space affected by
supershell activity. Recent results on supergiant shells in the LMC suggest
that while they do indeed help to organise the ISM into over-dense structures,
their global contribution to molecular cloud formation is of the order of only
~10%.Comment: Proceedings of IAUS 292 - Molecular Gas, Dust, and Star Formation in
Galaxies, eds. T. Wong & J. Ott. 4 pages, 3 figure
Simulating Impacts of Extreme Weather Events on Urban Transport Infrastructure in the UK
Urban areas face many risks from future climate change and their infrastructure will be placed under more pressure
due to changes in climate extremes. Using the Tyndall Centre Urban Integrated Assessment Framework, this paper
describes a methodology used to assess the impacts of future climate extremes on transport infrastructure in
London. Utilising high-resolution projections for future climate in the UK, alongside stochastic weather generators
for downscaling, urban temperature and flooding models are used to provide information on the likelihood of future
extremes. These are then coupled with spatial network models of urban transport infrastructure and, using thresholds
to define the point at which systems cease to function normally, disruption to the networks can be simulated.
Results are shown for both extreme heat and urban surface water flooding events and the impacts on the travelling
population, in terms of both disruption time and monetary cost
Kinetics of the reduction of metalloproteins by chromous ion
The reduction of Cu(330) in Rhus vernicifera laccase by chromous ion is 30% faster than reduction of Cu(614) at room temperature [pH 4.8, µ = 0.1 (NaCl)], and two parallel first-order paths, attributed to heterogeneity of the protein, are observed at both wavelengths. The reactions of stellacyanin, spinach and French-bean plastocyanins, and cytochrome c with chromous ion under similar conditions are faster than that with laccase by factors of 102 to 104, and are first order in protein concentration. Comparison of rates and activation parameters for the reduction of "blue" copper in laccase, stellacyanin, and the two plastocyanins indicates that reduction of the Cu(614) site in laccase may occur by intramolecular electron transfer from one of the Cu(330) sites. Our value of ΔH (17.4 kcal/mol) for the chromous ion reduction of cytochrome c is consistent with a mechanism in which major conformational changes in the protein must accompany electron transfer
BRAVO economic study of LANDSAT follow-on
The LANDSAT Follow-On satellite consists of two major systems: the instrument module and the Multi-Mission Modular Spacecraft (MMS). The instrument module contains the thematic mapper and the five-band multispectral scanner instruments. The instrument module also includes the solar array, the tracking and data relay satellite (TDRS) antenna, and the wideband data module. The MMS contains the modularized and standardized power, propulsion, attitude control, and command and data handling subsystems. The Shuttle will be supporting the LANDSAT Follow-On system. The LANDSAT Follow-On Project plans two Delta 3910 launches. The first is scheduled for 1981; the second Delta launch will occur as needed to keep one satellite operational on orbit. The second satellite will be ready six months after the first. It could be launched any time after that. Shuttle support of the system could begin in early 1983 but would be scheduled to start after the second Delta launch
Abell 1033: birth of a radio phoenix
Extended steep-spectrum radio emission in a galaxy cluster is usually
associated with a recent merger. However, given the complex scenario of galaxy
cluster mergers, many of the discovered sources hardly fit into the strict
boundaries of a precise taxonomy. This is especially true for radio phoenixes
that do not have very well defined observational criteria. Radio phoenixes are
aged radio galaxy lobes whose emission is reactivated by compression or other
mechanisms. Here, we present the detection of a radio phoenix close to the
moment of its formation. The source is located in Abell 1033, a peculiar galaxy
cluster which underwent a recent merger. To support our claim, we present
unpublished Westerbork Synthesis Radio Telescope and Chandra observations
together with archival data from the Very Large Array and the Sloan Digital Sky
Survey. We discover the presence of two sub-clusters displaced along the N-S
direction. The two sub-clusters probably underwent a recent merger which is the
cause of a moderately perturbed X-ray brightness distribution. A steep-spectrum
extended radio source very close to an AGN is proposed to be a newly born radio
phoenix: the AGN lobes have been displaced/compressed by shocks formed during
the merger event. This scenario explains the source location, morphology,
spectral index, and brightness. Finally, we show evidence of a density
discontinuity close to the radio phoenix and discuss the consequences of its
presence.Comment: accepted MNRA
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