14,098 research outputs found
Chemistry and kinematics of the pre-stellar core L1544: Constraints from H2D+
This paper explores the sensitivity of line profiles of H2D+, HCO+ and N2H+,
observed towards the center of L1544, to various kinematic and chemical
parameters. The total width of the H2D+ line can be matched by a static model
and by models invoking ambipolar diffusion and gravitational collapse. The
derived turbulent line width is b=0.15 km/s for the static case and <~ 0.05
km/s for the collapse case. However, line profiles of HC18O+ and N2H+ rule out
the static solution. The double-peaked H2D+ line shape requires either infall
speeds in the center that are much higher than predicted by ambipolar diffusion
models, or a shell-type distribution of H2D+, as is the case for HCO+ and N2H+.
At an offset of ~20 arcsec from the dust peak, the H2D+ abundance drops by a
factor of ~5.Comment: four pages, two colour figures; to appear in The Dense Interstellar
Medium in Galaxies, proceedings of the fourth Cologne-Bonn-Zermatt Symposium,
Sept 22-26, 200
The bird: A pressure-confined explosion in the interstellar medium
The non-thermal radio continuum source G5.3-1.0, mapped at 20 cm with the Very Large Array (VLA) by Becker and Helfand, has an unusual bird-like shape. In order to determine possible interaction of this source with adjacent cold gas, we have mapped this region in the J=1-0 line of CO using the AT and T Bell Laboratories 7m antenna and the FCRAO 14m antenna. The map shown contains 1859 spectra sampled on a 1.5 arcminute grid; each spectrum has an rms noise of 0.2 K in 1 MHz channels. There are several molecular clouds at different velocities along the line of sight. The outer regions of a previously unknown Giant Molecular Cloud (GMC) at l=4.7 deg., b=-0.85 deg., v=200 km s(-1) appears to be interacting with G5.3-10: the molecular cloud has a bird-shaped hole at the position of the continuum source, except that the brightest continuum point (the bird's head) appears to be embedded in the cloud. The velocity of this GMC indicates it is within 2 kpc of the galactic center. The morphology suggests that a supernova or other explosive event occurred near the outside of the GMC, in a region where (n) is approximately 300 cm(-3), and expanded into a region of lower density and pressure. The pressures, densities, and velocity gradients of molecular clouds near the galactic center are on average higher than those of clouds near the Sun. We therefore expect that Type II supernovae near the galactic center would be distorted by their interactions with their parent molecular clouds
A New Measurement of the Stellar Mass Density at z~5: Implications for the Sources of Cosmic Reionization
We present a new measurement of the integrated stellar mass per comoving
volume at redshift 5 determined via spectral energy fitting drawn from a sample
of 214 photometrically-selected galaxies with z'<26.5 in the southern GOODS
field. Following procedures introduced by Eyles et al. (2005), we estimate
stellar masses for various sub-samples for which reliable and unconfused
Spitzer IRAC detections are available. A spectroscopic sample of 14 of the most
luminous sources with =4.92 provides a firm lower limit to the stellar mass
density of 1e6 Msun/Mpc^3. Several galaxies in this sub-sample have masses of
order 10^11 Msun implying significant earlier activity occurred in massive
systems. We then consider a larger sample whose photometric redshifts in the
publicly-available GOODS-MUSIC catalog lie in the range 4.4 <z 5.6. Before
adopting the GOODS-MUSIC photometric redshifts, we check the accuracy of their
photometry and explore the possibility of contamination by low-z galaxies and
low-mass stars. After excising probable stellar contaminants and using the z'-J
color to exclude any remaining foreground red galaxies, we conclude that 196
sources are likely to be at z~5. The implied mass density from the unconfused
IRAC fraction of this sample, scaled to the total available, is 6e6 Msun/Mpc^3.
We discuss the uncertainties as well as the likelihood that we have
underestimated the true mass density. Including fainter and quiescent sources
the total integrated density could be as high as 1e7 Msun/Mpc^3. Using the
currently available (but highly uncertain) rate of decline in the star
formationhistory over 5 <z< 10, a better fit is obtained for the assembled mass
at z~5 if we admit significant dust extinction at early times or extend the
luminosity function to very faint limits. [abridged]Comment: Accepted for Publication in ApJ, 39 page
Synchronizing Sequencing Software to a Live Drummer
Copyright 2013 Massachusetts Institute of Technology. MIT allows authors to archive published versions of their articles after an embargo period. The article is available at
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British research in accounting and finance (2001–2007): the 2008 research assessment exercise
No abstract available
Preventing pain on injection of propofol: A comparison between lignocaine pre-treatment and lignocaine added to propofol
Publisher's copy made available with the permission of the publisherA randomized double-blind study compared two methods of preventing the pain from injection of propofol, lignocaine pre-treatment followed by propofol and lignocaine added to propofol. One hundred patients received a 4 ml solution intravenously with a venous tourniquet for 1 minute, followed by propofol mixed with 2 ml of solution. Patients were divided into two treatment groups of 50 patients each: 4 ml 1% lignocaine pre-treatment followed by propofol and 2 ml saline, or 4 ml saline followed by propofol and 2 ml 2% lignocaine. Pain was assessed with a 100 mm visual analogue scale after induction and in recovery. The incidence of injection pain was 8% in the propofol mixed with lignocaine group, and 28% in the lignocaine pre-treatment group. This difference is statistically significant (P=0.017). For those patients who had pain, the mean pain score was 26.5 on induction for the propofol with lignocaine group (n=4), while the mean score was 44.4 for the pre-treatment group (n=13). The difference was not statistically significant (P=0.25). None of the propofol mixed with lignocaine group recalled pain, while 13 of the pre-treatment group did so. Lignocaine pre-treatment does not improve the immediate or the recalled comfort of patients during propofol induction when compared to lignocaine added to propofol. It is recommended that lignocaine should be added to propofol for induction rather than given before induction.P. Lee, W. J. Russellhttp://www.aaic.net.au/Article.asp?D=200339
The Jabal Akhdar Dome in the Oman Mountains : evolution of a dynamic fracture system
Acknowledgments: This study was carried out within the framework of DGMK (German Society for Petroleum and Coal Science and Technology) research project 718 “Mineral Vein Dynamics Modelling,” which is funded by the companies ExxonMobil Production Deutschland GmbH, GDF SUEZ E&P Deutschland GmbH, RWE Dea AG and Wintershall Holding GmbH, within the basic research program of the WEG Wirtschaftsverband Erdo¨l- und Erdgasgewinnung e.V. We thank the companies for their financial support and their permission to publish these results. The German University of Technology in Oman (GU-Tech) is acknowledged for its logistic support. We gratefully acknowledge the reviewers Andrea Billi and Jean-Paul Breton, whose constructive reviews greatly improved the manuscriptPeer reviewedPreprin
Anxiety in cancer patients
Anxiety is common in cancer patient populations, and must often initially be recognized and managed by cancer care professionals. This article reviews the recent oncology and mental health literature on anxiety. The aim is to help those involved in cancer patient care who are not specialists in mental health to understand the nature of anxiety, and discriminate morbid from normal anxiety. We review recent research into the association of anxiety with events during diagnosis and management of cancer, highlighting the importance of the meaning of events to an individual as an important factor in making people anxious. Lastly we review management strategies which might be used by cancer care professionals, in particular the importance of an awareness of specific patterns of communication which may alleviate or maintain anxiety for some cancer patients. © 2000 Cancer Research Campaig
Keck Spectroscopy of Faint 3<z<8 Lyman Break Galaxies:- Evidence for a Declining Fraction of Emission Line Sources In the Redshift Range 6<z<8
Using deep Keck spectroscopy of Lyman break galaxies selected from infrared
imaging data taken with WFC3/IR onboard the Hubble Space Telescope, we present
new evidence for a reversal in the redshift-dependent fraction of star forming
galaxies with detectable Lyman alpha emission in the redshift range 6.3 < z <
8.8. Our earlier surveys with the DEIMOS spectrograph demonstrated a
significant increase with redshift in the fraction of line emitting galaxies
over the interval 4 < z < 6, particularly for intrinsically faint systems which
dominate the luminosity density. Using the longer wavelength sensitivities of
LRIS and NIRSPEC, we have targeted 19 Lyman break galaxies selected using
recent WFC3/IR data whose photometric redshifts are in the range 6.3 < z < 8.8
and which span a wide range of intrinsic luminosities. Our spectroscopic
exposures typically reach a 5-sigma sensitivity of < 50 A for the rest-frame
equivalent width (EW) of Lyman alpha emission. Despite the high fraction of
emitters seen only a few hundred million years later, we find only 2 convincing
and 1 possible line emitter in our more distant sample. Combining with
published data on a further 7 sources obtained using FORS2 on the ESO VLT, and
assuming continuity in the trends found at lower redshift, we discuss the
significance of this apparent reversal in the redshift-dependent Lyman alpha
fraction in the context of our range in continuum luminosity. Assuming all the
targeted sources are at their photometric redshift and our assumptions about
the Lyman alpha EW distribution are correct, we would expect to find so few
emitters in less than 1% of the realizations drawn from our lower redshift
samples. Our new results provide further support for the suggestion that, at
the redshifts now being probed spectroscopically, we are entering the era where
the intergalactic medium is partially neutral.Comment: 8 pages, 5 figures, Accepted to ApJ 10/1/1
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