1,811 research outputs found
A deep search for 21cm absorption in high redshift damped Lyman- systems
We present deep GMRT 21cm absorption spectra of 10 damped Lyman-
systems (DLAs), of which 8 are at redshifts z \ga 1.3. HI absorption was
detected in only one DLA, the absorber toward PKS 1629+12, which
has been identified with a luminous spiral galaxy; the spin temperature limit
( K) derived from our observations continues the trend of DLAs
associated with bright spirals having low spin temperatures. In 7 of the
remaining 9 systems, the observations place strong lower limits on the spin
temperature of the HI gas.
The sample of DLAs searched for 21cm absorption now consists of 31 systems,
with estimates available in 24 cases; of these, 16 are at and 8
at , with 11 (all at ) having optical IDs. For the latter 11
systems, we find that all low DLAs have been identified with luminous
galaxies, while all high (T_s \ga 1000 K) DLAs have been identified
with either LSBs or dwarfs. DLA spin temperatures thus appear to correlate with
galaxy type, with no correlation seen between and impact parameter.
The trend that low DLAs exhibit both high and low values while high
redshift (z \ga 3) DLAs only show high spin temperatures is present in this
expanded data set. Based on this difference in spin temperatures, the Gehan
test rules out the hypothesis that DLAs at and DLAs at are
drawn from the same parent population at ~ 99 % confidence level.
Finally, we estimate upper limits on the fraction of cold HI, , in
the z \ga 3 DLAs. In local spirals, ; in contrast, we find
that in all 7 high DLAs, with in 5 of the 7
cases. (abridged)Comment: 13 pages, 5 figures. Accepted for publication in Astronomy &
Astrophysic
A search for molecules in damped Lyman-alpha absorbers occulting millimetre-loud quasars
We have used the SEST 15-metre and Onsala 20-metre telescopes to perform deep
(r.m.s. >~ 30 mJy) integrations of various molecular rotational transitions
towards damped Lyman-alpha absorption systems (DLAs) known to occult
millimetre-loud quasars. We have observed 6 new systems and improved the
existing limits for 11 transitions. These limits may be approaching the
sensitivities required to detect new systems and we present a small number of
candidate systems which we believe warrant further observation.Comment: 7 pages, 1 PS figure, 4 tables. Accepted by A&
Infection of the brown alga Ectocarpus siliculosus by the oomycete Eurychasma dicksonii induces oxidative stress and halogen metabolism
Acknowledgments We would like to thank the Aberdeen Proteome Facility, especially Phil Cash, David Stead and Evelyn Argo for assistance with 2D electrophoresis and mass spectrometry. M.S. gratefully acknowledges a Marie Curie PhD fellowship from the European Commission (ECOSUMMER, MEST-CT-2005-20501), a joint FEMS/ESCMID Research Fellowship and the Genomia Fund. C.M.M.G. is supported by a Marie Curie postdoctoral fellowship (MEIF-CT-2006-022837), a Marie Curie Re-Integration Grant (PERG03-GA-2008-230865) and a New Investigator grant from the UK Natural Environment Research Council (NERC, grant NE/J00460X/1). F.C.K. would like to thank NERC for funding (grants NE/D521522/1, NE/F012705/1 and Oceans 2025 / WP 4.5). L.J.G.-B., C.M.M.G., F.C.K. and P.W. would like to acknowledge funding from NERC for a Strategic Ocean Funding Initiative award (NE/F012578/1). Funding from the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011) and from the TOTAL Foundation (Paris) to F.C.K. is gratefully acknowledged. Finally, we would like to thank the two anonymous referees for constructive suggestions to improve our manuscript.Peer reviewedPublisher PD
Gamma Ray Burst Predictions for the Fermi Gamma Ray Space Telescope
Results of a phenomenological model to estimate the GRB detection rate by the
Fermi Gamma ray Space Telescope are reported. This estimate is based on the
BATSE 4B GRB fluence distribution, the mean ratio of fluences measured at 100
MeV - 5 GeV with EGRET and at 20 keV - 2 MeV with BATSE, and the mean EGRET GRB
spectrum for the 5 EGRET spark-chamber GRBs. For a 10% fluence ratio and a
number spectral index alpha_1 = -2 at 100 MeV - 5 GeV energies, we estimate a
rate of ~ 20 and 4 GRBs per yr in the Fermi Large Area Telescope field of view
with at least 5 photons with energy E > 100 MeV and E > 1 GeV, respectively. We
also estimate ~ 1.5 GRBs per yr in the Fermi FoV where at least 1 photon with
energy E > 10 GeV is detected. For these parameters, we estimate = 1 - 2 GRBs
per year detected with the Fermi telescope with more than 100 gamma rays with E
>~ 100$ MeV. Comparison predictions for alpha_1 = -2.2, different fluence
ratios, and the AGILE gamma-ray satellite are made. Searches for different
classes of GRBs using a diagram plotting 100 MeV - 10 GeV fluence vs. 20 keV -
20 MeV fluence is considered as a way to search for separate classes of GRBs
and, specifically, spectral differences between the short-hard and long
duration GRB classes, and for hard components in GRBs.Comment: 9 pages, 6 figures, Accepted for publication in ApJ; this version
contains an additional section that discusses the fluence estimates and
uncertainties for EGRET GRB
Two New Low Redshift 21cm Absorbers
As part of a larger program to identify low redshift radio analogues of the
damped Lyman-alpha (DLA) absorbers seen in the spectra of high redshift
quasars, Westerbork Synthesis Radio Telescope (WSRT) observations have
discovered two new HI 21cm absorption lines at z=0.394 and z=0.437 in the
spectra of the radio sources B 0248+430 and B 1243-072 respectively. These
sightlines and redshifts were selected for study on the basis of the previously
known low ionization absorption lines of MgII, and neither has been observed in
the Lyman-alpha line. The 21cm line observations provide information on column
densities, temperatures and kinematics of the thickest cold neutral clouds in
the absorbers.Comment: 6 pages incl. 2 figures, accepted for publication in the
Astrophysical Journal Letters, missing reference adde
An Imaging and Spectroscopic Study of the z=3.38639 Damped Lyman Alpha System in Q0201+1120: Clues to Star Formation Rate at High Redshift
We present the results of a series of imaging and spectroscopic observations
aimed at identifying and studying the galaxy responsible for the z = 3.38639
damped lya system in the z = 3.61 QSO Q0201+1120. We find that the DLA is part
of a concentration of matter which includes at least four galaxies (probably
many more) over linear comoving dimensions, greater than 5h^-1Mpc. The absorber
may be a 0.7 L* galaxy at an impact parameter of 15 h^-1 kpc, but follow-up
spectroscopy is still required for positive identification. The gas is
turbulent, with many absorption components distributed over approximately 270
km/s and a large spin temperature, T_s greater than 4000K. The metallicity is
relatively high for this redshift, Z(DLA) approximately 1/20 Z(solar). From
consideration of the relative ratios of elements which have different
nucleosynthetic timescales, it would appear that the last major episode of star
formation in this DLA occurred at z greater than 4.3, more than approximately
500 Myr prior to the time when we observe it.Comment: Accepted for publication in Ap
A Medical Support in Offshore Racing — Workshop on Medical Kit Inventory in Offshore Yacht Racing, 12–13 May 2017, Lorient, France
No abstrac
Statistics of galaxy warps in the HDF North and South
We present a statistical study of the presence of galaxy warps in the Hubble
deep fields. Among a complete sample of 45 edge-on galaxies above a diameter of
1.''3, we find 5 galaxies to be certainly warped and 6 galaxies as good
candidates. In addition, 4 galaxies reveal a characteristic U-warp. Compared to
statistical studies of local warps, and taking into account the strong bias
against observing the outer parts of galaxies at high redshift, these numbers
point towards a very high frequency of warps at z \sim 1: almost all galaxy
discs might be warped. Furthermore, the amplitude of warps are stronger than
for local warps. This is easily interpreted in terms of higher galaxy
interactions and matter accretion in the past. This result supports these two
mechanisms as the best candidates for the origin of early warps. The mean
observed axis ratio of our sample of edge-on galaxies is significantly larger
in the high-z sample than is found for samples of local spiral galaxies. This
might be due to disk thickening due to more frequent galaxy interactions.Comment: 9 pages, 7 figures, accepted in A and
Controls on gut phosphatisation : the trilobites from the Weeks Formation Lagerstätte (Cambrian; Utah)
Despite being internal organs, digestive structures are frequently preserved in Cambrian Lagerstätten. However, the reasons for their fossilisation and their biological implications remain to be thoroughly explored. This is particularly true with arthropods--typically the most diverse fossilised organisms in Cambrian ecosystems--where digestive structures represent an as-yet underexploited alternative to appendage morphology for inferences on their biology. Here we describe the phosphatised digestive structures of three trilobite species from the Cambrian Weeks Formation Lagerstätte (Utah). Their exquisite, three-dimensional preservation reveals unique details on trilobite internal anatomy, such as the position of the mouth and the absence of a differentiated crop. In addition, the presence of paired pygidial organs of an unknown function is reported for the first time. This exceptional material enables exploration of the relationships between gut phosphatisation and the biology of organisms. Indeed, soft-tissue preservation is unusual in these fossils as it is restricted to the digestive structures, which indicates that the gut played a central role in its own phosphatisation. We hypothesize that the gut provided a microenvironment where special conditions could develop and harboured a source of phosphorus. The fact that gut phosphatization has almost exclusively been observed in arthropods could be explained by their uncommon ability to store ions (including phosphorous) in their digestive tissues. However, in some specimens from the Weeks Formation, the phosphatisation extends to the entire digestive system, suggesting that trilobites might have had some biological particularities not observed in modern arthropods. We speculate that one of them might have been an increased capacity for ion storage in the gut tissues, related to the moulting of their heavily-mineralised carapace
Facilitating return to work through early specialist health-based interventions (FRESH): protocol for a feasibility randomised controlled trial
Background
Over one million people sustain traumatic brain injury each year in the UK and more than 10 % of these are moderate or severe injuries, resulting in cognitive and psychological problems that affect the ability to work. Returning to work is a primary rehabilitation goal but fewer than half of traumatic brain injury survivors achieve this. Work is a recognised health service outcome, yet UK service provision varies widely and there is little robust evidence to inform rehabilitation practice. A single-centre cohort comparison suggested better work outcomes may be achieved through early occupational therapy targeted at job retention. This study aims to determine whether this intervention can be delivered in three new trauma centres and to conduct a feasibility, randomised controlled trial to determine whether its effects and cost effectiveness can be measured to inform a definitive trial.
Methods/design
Mixed methods study, including feasibility randomised controlled trial, embedded qualitative studies and feasibility economic evaluation will recruit 102 people with traumatic brain injury and their nominated carers from three English UK National Health Service (NHS) trauma centres. Participants will be randomised to receive either usual NHS rehabilitation or usual rehabilitation plus early specialist traumatic brain injury vocational rehabilitation delivered by an occupational therapist. The primary objective is to assess the feasibility of conducting a definitive trial; secondary objectives include measurement of protocol integrity (inclusion/exclusion criteria, intervention adherence, reasons for non-adherence) recruitment rate, the proportion of eligible patients recruited, reasons for non-recruitment, spectrum of TBI severity, proportion of and reasons for loss to follow-up, completeness of data collection, gains in face-to-face Vs postal data collection and the most appropriate methods of measuring primary outcomes (return to work, retention) to determine the sample size for a larger trial.
Discussion
To our knowledge, this is the first feasibility randomised controlled trial of a vocational rehabilitation health intervention specific to traumatic brain injury. The results will inform the design of a definitive trial
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