4,025 research outputs found
A CO Survey of Gravitationally Lensed Quasars with the IRAM Interferometer
We present the results of a CO survey of gravitationally lensed quasars,
conducted with the Plateau de Bure Interferometer over the last three years.
Among the 18 objects surveyed, one was detected in CO line emission, while six
were detected in the continuum at 3mm and three in the continuum at 1mm. The
low CO detection rate may at least in part be due to uncertainties in the
redshifts derived from quasar broad emission lines. The detected CO source, the
z=3.2 radio quiet quasar MG0751+2716, is quite strong in the CO(4-3) line and
in the millimeter/submillimeter continuum, the latter being emission from cool
dust. The integrated CO line flux is 5.96 +- 0.45 Jy.km/s, and the total
molecular gas mass is estimated to be in the range M(H_2) = 1.6-3.1 X 10^9
solar masses.Comment: 5 pages, 2 figures, uses aa.cls and psfig.st
First redshift determination of an optically/UV faint submillimeter galaxy using CO emission lines
We report the redshift of a distant, highly obscured submm galaxy (SMG),
based entirely on the detection of its CO line emission. We have used the newly
commissioned Eight-MIxer Receiver (EMIR) at the IRAM 30m telescope, with its 8
GHz of instantaneous dual-polarization bandwidth, to search the 3-mm
atmospheric window for CO emission from SMMJ14009+0252, a bright SMG detected
in the SCUBA Lens Survey. A detection of the CO(3--2) line in the 3-mm window
was confirmed via observations of CO(5--4) in the 2-mm window. Both lines
constrain the redshift of SMMJ14009+0252 to z=2.9344, with high precision (dz=2
10^{-4}). Such observations will become routine in determining redshifts in the
era of the Atacama Large Millimeter/submillimeter Array (ALMA).Comment: 5 pages, 3 figures, accepted by ApJ
A Morphological Assessment of Bovine Chondrocytes Cultured on Poly(Ethyl Methacrylate)/Tetrahydrofurfuryl Methacrylate
A heterocyclic methacrylate polymer system, PEMA/THFMA, has shown potential as a biomaterial for cartilage repair in a rabbit model and has properties making it suitable for use clinically. The ability of the polymer system, PEMA/THFMA, and a related system, PEMA/HEMA, to support chondrocytes in vitro was assessed by scanning electron microscopy. Chondrocytes adhered to the surface of the PEMA/THFMA by day one, having a rounded morphology and clustered appearance opposed to the Thermanox® control, where the cells had spread out and become fibroblastic in appearance. The chondrocytes divided rapidly on the PEMA/ THFMA system by day three and had completely covered the surface by day seven. In contrast, chondrocytes did not adhere well to the more hydrophilic PEMA/ HEMA system. A few cells were seen on the surface by day one and by days three and seven, there was no evidence of cell growth or spreading across the surface.
In conclusion, the PEMA/THFMA system can support chondrocytes in vitro, whereas the PEMA/HEMA system does not
Quantum Estimation of Parameters of Classical Spacetimes
We describe a quantum limit to measurement of classical spacetimes.
Specifically, we formulate a quantum Cramer-Rao lower bound for estimating the
single parameter in any one-parameter family of spacetime metrics. We employ
the locally covariant formulation of quantum field theory in curved spacetime,
which allows for a manifestly background-independent derivation. The result is
an uncertainty relation that applies to all globally hyperbolic spacetimes.
Among other examples, we apply our method to detection of gravitational waves
using the electromagnetic field as a probe, as in laser-interferometric
gravitational-wave detectors. Other applications are discussed, from
terrestrial gravimetry to cosmology.Comment: 23 pages. This article supersedes arXiv:1108.522
The quasar Q0957+561: Lensed CO emission from a disk at z~1.4?
In recent years large efforts have been made to detect molecular gas towards
high redshifted objects. Up to now the literature reports on only two cases of
CO-detection in quasars at a redshift between 1 and 2 - Q0957+561, a
gravitationally lensed system at z=1.41 (Planesas et al. 1999), and HR10 at
z=1.44 (Andreani et al. 2000). According to Planesas et al. (1999), 12CO(2-1)
emission was detected towards both the lensed images of Q0957+561 with the IRAM
Plateau de Bure Interferometer (PdBI). In contrast to the optical spectra of
the two images which support the idea that they are images of one and the same
object, the CO-spectra were surprisingly different: the southern image (named
CO-B) shows a single blueshifted line whereas a double-peaked line profile with
a blue- and a redshifted part appears towards the northern image (CO-A). Based
on the observations and on simulations with a gravitational lens program, we
are tempted to argue that the line profile traces the presence of molecular gas
of a disk in the host galaxy around the quasar. We have now new observations
with the PdBI providing the necessary sensitivity to corroborate our disk
model.Comment: 4 pages, 1 figure, to appear in "Proceedings of the 4th
Cologne-Bonn-Zermatt-Symposium", ed. S. Pfalzner, C. Kramer, C. Straubmeier,
and A. Heithausen (Springer Verlag
New Observations and a New Interpretation of CO(3--2) in IRAS F10214+4724
New observations with the IRAM interferometer of CO(3--2) from the highly
luminous galaxy IRAS F10214+4724 show the source is 1.5'' x <= 0.9'' ; they
display no evidence of any velocity gradient. This size, together with optical
and IR data that show the galaxy is probably gravitationally lensed, lead to a
new model for the CO distribution. In contrast to many lensed objects, we have
a good estimate of the intrinsic CO and far IR surface brightnesses, so we can
derive the CO and far IR/sub-mm magnifications. The CO is magnified 10 times
and has a true radius of 400 pc. and the far IR is magnified 13 times and has a
radius of 250 pc. The true far IR luminosity is 4 to 7e12 Lsun and the
molecular gas mass is 2e10 Msun . This is nearly an order of magnitude less
than previously estimated. Because the far IR magnification is lower than the
mid and near IR magnification, the intrinsic spectral energy distribution now
peaks in the far infrared. That is, nearly all of the energy of this object is
absorbed and re-emitted in the far infrared. In CO luminosity, molecular gas
content, CO linewidth, and corrected far IR luminosity, 10214+472 is a typical,
warm, IR ultraluminous galaxy.Comment: 18 pages, including 3 figures, of gzipped, uuencoded postscript. To
be published Ap.J. Letter
Developing a cerebral palsy-specific preference-based measure for a six-dimensional classification system (CP-6D): protocol for a valuation study.
INTRODUCTION: Cerebral palsy (CP) is a lifelong condition. The CP quality of life (CPQOL) instrument is a frequently used disease-specific instrument to assess health-related quality of life (HRQoL) in people with CP, but it cannot be used to generate quality-adjusted life years (QALY) which are the basis of cost utility analysis (CUA). Generic utility instruments (such as the EQ-5D or SF-6D) that are used to value HRQOL may be insensitive to small but important health changes in children with CP. This study aims to generate a preference-based scoring algorithm for the CP six dimensions (CP-6D), a classification system developed from the CPQOL. METHODS AND ANALYSIS: A discrete choice experiment with duration (DCEtto) will be administrated to value health states described by the CP-6D classification system. These health states will be presented to members of Australian general population and parents of children with CP via an online survey. Conditional logit regression will be used to produce the utility algorithm for CP-6D. ETHICS AND DISSEMINATION: The Griffith University Human Research Ethics Committee approved for the study (reference HREC/number 2018/913). The developed algorithm can be applied to previous and future economic evaluation of interventions and treatments targeting people with CP which have used either the CPQOL or CP-6D
Using New Submillimetre Surveys to Identify the Evolutionary Status of High-z Galaxies
This paper describes a key submillimetre survey which we are currently
conducting to address some of the outstanding questions in cosmology - how, at
what epoch and over what period of time did massive galaxies form at high
redshift? A summary of the technical feasibility of future submillimetre
observations with new ground-based, airborne and satellite telescopes is also
presented.Comment: 6 pages, 3 postscript figures, LaTex uses Kluwer book style file
crckapb10.sty, to appear in "Observational Cosmology with the New Radio
Surveys", 13-15 January 1997, Puerto de la Cruz, Tenerife, M.Bremer,
N.Jackson, I.Perez-Fournon (eds.), Kluwe
Faint Radio Sources and Star Formation History
Faint extragalactic radio sources provide important information about the
global history of star formation. Sensitive radio observations of the Hubble
Deep Field and other fields have found that sub-mJy radio sources are
predominantly associated with star formation activity rather than AGN. Radio
observations of star forming galaxies have the advantage of being independent
of extinction by dust. We use the FIR-radio correlation to compare the radio
and FIR backgrounds, and make several conclusions about the star forming
galaxies producing the FIR background. We then use the redshift distribution of
faint radio sources to determine the evolution of the radio luminosity
function, and thus estimate the star formation density as a function of
redshift.Comment: 12 pages, 9 figures, latex using texas.sty, to appear in the CD-ROM
Proceedings of the 19th Texas Symposium on Relativistic Astrophysics and
Cosmology, held in Paris, France, Dec. 14-18, 1998. Eds.: J. Paul, T.
Montmerle, and E. Aubourg (CEA Saclay). No changes to paper, just updated
publication info in this commen
Quantum Connectivity of Space-Time and Gravitationally Induced Decorrelation of Entanglement
We discuss an alternative formulation of the problem of quantum optical
fields in a curved space-time using localized operators. We contrast the new
formulation with the standard approach and find observable differences for
entangled states. We propose an experiment in which an entangled pair of
optical pulses are propagated through non-uniform gravitational fields and find
that the new formulation predicts de-correlation of the optical entanglement
under experimentally realistic conditions
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