257 research outputs found
Discovery of a New Nearby Star
We report the discovery of a nearby star with a very large proper motion of
5.06 +/- 0.03 arcsec/yr. The star is called SO025300.5+165258 and referred to
herein as HPMS (high proper motion star). The discovery came as a result of a
search of the SkyMorph database, a sensitive and persistent survey that is well
suited for finding stars with high proper motions. There are currently only 7
known stars with proper motions > 5 arcsec/yr. We have determined a preliminary
value for the parallax of 0.43 +/- 0.13 arcsec. If this value holds our new
star ranks behind only the Alpha Centauri system (including Proxima Centauri)
and Barnard's star in the list of our nearest stellar neighbors. The spectrum
and measured tangential velocity indicate that HPMS is a main-sequence star
with spectral type M6.5. However, if our distance measurement is correct, the
HPMS is underluminous by 1.2 +/- 0.7 mag.Comment: 5 pages, 3 figures. Submitted to ApJ Letter
Chandra Observation of the Cluster Environment of a WAT Radio Source in Abell 1446
Wide-angle tail (WAT) radio sources are often found in the centers of galaxy
clusters where intracluster medium (ICM) ram pressure may bend the lobes into
their characteristic C-shape. We examine the low redshift (z=0.1035) cluster
Abell 1446, host to the WAT radio source 1159+583. The cluster exhibits
possible evidence for a small-scale cluster-subcluster merger as a cause of the
WAT radio source morphology. This evidence includes the presence of temperature
and pressure substructure along the line that bisects the WAT as well as a
possible wake of stripped interstellar material or a disrupted cool core to the
southeast of the host galaxy. A filament to the north may represent cool,
infalling gas that's contributing to the WAT bending while spectroscopically
determined redshifts of member galaxies may indicate some component of a merger
occurring along the line-of-sight. The WAT model of high flow velocity and low
lobe density is examined as another scenario for the bending of 1159+583. It
has been argued that such a model would allow the ram pressure due to the
galaxy's slow motion through the ICM to shape the WAT source. A temperature
profile shows that the cluster is isothermal (kT= 4.0 keV) in a series of
annuli reaching a radius of 400 kpc. There is no evidence of an ongoing cooling
flow. Temperature, abundance, pressure, density, and mass profiles, as well as
two-dimensional maps of temperature and pressure are presented.Comment: 40 AASTeX pages including 15 postscript figures; accepted for
publication in Ap
Study of exciton-polariton modes in nanocrystalline thin films of CuCl using reflectance spectroscopy
The conserved C-terminus of the PcrA/UvrD helicase interacts directly with RNA polymerase
Copyright: © 2013 Gwynn et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by a Wellcome Trust project grant to MD (Reference: 077368), an ERC starting grant to MD (Acronym: SM-DNA-REPAIR) and a BBSRC project grant to PM, NS and MD (Reference: BB/I003142/1). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Peer reviewedPublisher PD
Does Screening for Pain Correspond to High Quality Care for Veterans?
Routine numeric screening for pain is widely recommended, but its association with overall quality of pain care is unclear.
To assess adherence to measures of pain management quality and identify associated patient and provider factors.
A cross-sectional visit-based study.
One hundred and forty adult VA outpatient primary care clinic patients reporting a numeric rating scale (NRS) of moderate to severe pain (four or more on a zero to ten scale). Seventy-seven providers completed a baseline survey regarding general pain management attitudes and a post-visit survey regarding management of 112 participating patients.
We used chart review to determine adherence to four validated process quality indicators (QIs) including noting pain presence, pain character, and pain control, and intensifying pharmacological intervention. The average NRS was 6.7. Seventy-three percent of charts noted the presence of pain, 13.9% the character, 23.6% the degree of control, and 15.3% increased pain medication prescription. Charts were more likely to include documentation of pain presence if providers agreed that “patients want me to ask about pain” and “pain can have negative consequences on patient’s functioning”. Charts were more likely to document character of pain if providers agreed that “patients are able to rate their pain”. Patients with musculoskeletal pain were less likely to have chart documentation of character of pain.
Despite routine pain screening in VA, providers seldom documented elements considered important to evaluation and treatment of pain. Improving pain care may require attention to all aspects of pain management, not just screening
Theoretical analysis of nucleation and growth of ZnO nanostructures in vapour phase transport growth
This paper discusses the growth atmosphere, condensing species and nucleation conditions relevant to vapour phase transport growth of ZnO nanostructures, including the molecular parameters and thermodynamics of the gas phase ZnO molecule and its importance compared to atomic Zn and molecular O2. The partial pressure of molecular ZnO in a Zn/O2 mix at normal ZnO growth temperatures is 6x10^-7 of the Zn partial pressures. In typical vapour phase transport growth conditions, using carbothermal reduction, the Zn vapour is always undersaturated while the ZnO vapour is always supersaturated. In the case of the ZnO vapour, our
analysis suggests that the barrier to homogeneous nucleation (or heterogeneous nucleation at unseeded/uncatalysed areas of the substrates) is too large for nucleation of this species to take place, which is consistent with experimental evidence that nanostructures will not grow on unseeded areas of substrates. In the presence of suitable accommodation sites, due to ZnO seeds,
growth can occur via Zn vapour condensation (followed by oxidation) and via direct condensation of molecular ZnO (whose flux at the surface, although less than that of Zn vapour, is still sufficient to yield an appreciable nanostructure deposit). The balance between these two condensing species is likely to be a sensitive function of growth parameters and could explain both the diversity of reported nanostructure morphologies and the challenges to be faced in developing reproducible and scalable growth systems for specific applicable morphologies
Suzaku Observations of Luminous Quasars: Revealing the Nature of High-Energy Blazar Emission in Quiescent States
We present the results from the Suzaku X-ray observations of five
flat-spectrum radio quasars (FSRQs), namely PKS0208-512, Q0827+243,
PKS1127-145, PKS1510-089 and 3C 454.3. All these sources were additionally
monitored simultaneously or quasi-simultaneously by the Fermi satellite in
gamma-rays and the Swift UVOT in the UV and optical bands, respectively. We
constructed their broad-band spectra covering the frequency range from 10^14 Hz
up to 10^25 Hz, and those reveal the nature of high-energy emission of luminous
blazars in their low-activity states. The analyzed X-ray spectra are well
fitted by a power-law model with photoelectric absorption. In the case of
PKS0208-512, PKS1127-145, and 3C 454.3, the X-ray continuum showed indication
of hard-ening at low-energies. Moreover, when compared with the previous X-ray
observations, we see a significantly increasing contribution of low-energy
photons to the total X-ray fluxes when the sources are getting fainter. The
same behavior can be noted in the Suzaku data alone. A likely explanation
involves a variable, flat-spectrum component produced via inverse-Compton (IC)
emission, plus an additional, possibly steady soft X-ray component prominent
when the source gets fainter. This soft X-ray excess is represented either by a
steep powerlaw (photon indices Gamma ~ 3 - 5) or a blackbody-type emission with
temperatures kT ~ 0.1-0.2 keV. We model the broad-band spectra spectra of the
five observed FSRQs using synchrotron self-Compton (SSC) and/or
external-Compton radiation (ECR) models. Our modeling suggests that the
difference between the low and high-activity states in luminous blazars is due
to the different total kinetic power of the jet, most likely related to varying
bulk Lorentz factor of the outflow within the blazar emission zone.Comment: 36 pages, 8 figures, 11 tables. Accepted for publication in the
Astrophysical Journal
Fermi observations of high-energy gamma-ray emission from GRB 090217A
The Fermi observatory is advancing our knowledge of Gamma-Ray Bursts (GRBs)
through pioneering observations at high energies, covering more than 7 decades
in energy with the two on-board detectors, the Large Area Telescope (LAT) and
the Gamma-ray Burst Monitor (GBM). Here we report on the observation of the
long GRB 090217A which triggered the GBM and has been detected by the LAT with
a significance greater than 9 sigma. We present the GBM and LAT observations
and on-ground analyses, including the time-resolved spectra and the study of
the temporal profile from 8 keV up to 1 GeV. All spectra are well reproduced by
a Band model. We compare these observations to the first two LAT-detected, long
bursts GRB 080825C and GRB 080916C. These bursts were found to have
time-dependent spectra and exhibited a delayed onset of the high-energy
emission, which are not observed in the case of GRB 090217A. We discuss some
theoretical implications for the high-energy emission of GRBs.Comment: 17 pages, 4 figures. Contact Authors: Fred, Piron; Sara, Cutini;
Andreas, von Kienli
Habitable Zones in the Universe
Habitability varies dramatically with location and time in the universe. This
was recognized centuries ago, but it was only in the last few decades that
astronomers began to systematize the study of habitability. The introduction of
the concept of the habitable zone was key to progress in this area. The
habitable zone concept was first applied to the space around a star, now called
the Circumstellar Habitable Zone. Recently, other, vastly broader, habitable
zones have been proposed. We review the historical development of the concept
of habitable zones and the present state of the research. We also suggest ways
to make progress on each of the habitable zones and to unify them into a single
concept encompassing the entire universe.Comment: 71 pages, 3 figures, 1 table; to be published in Origins of Life and
Evolution of Biospheres; table slightly revise
Discovery of Pulsed -rays from PSR J0034-0534 with the Fermi LAT: A Case for Co-located Radio and -ray Emission Regions
Millisecond pulsars (MSPs) have been firmly established as a class of
gamma-ray emitters via the detection of pulsations above 0.1 GeV from eight
MSPs by the Fermi Large Area Telescope (LAT). Using thirteen months of LAT data
significant gamma-ray pulsations at the radio period have been detected from
the MSP PSR J0034-0534, making it the ninth clear MSP detection by the LAT. The
gamma-ray light curve shows two peaks separated by 0.2740.015 in phase
which are very nearly aligned with the radio peaks, a phenomenon seen only in
the Crab pulsar until now. The 0.1 GeV spectrum of this pulsar is well
fit by an exponentially cutoff power law with a cutoff energy of 1.80.1 GeV and a photon index of 1.50.1, first errors are
statistical and second are systematic. The near-alignment of the radio and
gamma-ray peaks strongly suggests that the radio and gamma-ray emission regions
are co-located and both are the result of caustic formation.Comment: 20 pages, 3 figures, 2 tables. Accepted for publication in Ap
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