441 research outputs found
Black hole accretion and star formation as drivers of gas excitation and chemistry in Mrk231
We present a full high resolution SPIRE FTS spectrum of the nearby
ultraluminous infrared galaxy Mrk231. In total 25 lines are detected, including
CO J=5-4 through J=13-12, 7 rotational lines of H2O, 3 of OH+ and one line each
of H2O+, CH+, and HF. We find that the excitation of the CO rotational levels
up to J=8 can be accounted for by UV radiation from star formation. However,
the approximately flat luminosity distribution of the CO lines over the
rotational ladder above J=8 requires the presence of a separate source of
excitation for the highest CO lines. We explore X-ray heating by the accreting
supermassive black hole in Mrk231 as a source of excitation for these lines,
and find that it can reproduce the observed luminosities. We also consider a
model with dense gas in a strong UV radiation field to produce the highest CO
lines, but find that this model strongly overpredicts the hot dust mass in
Mrk231. Our favoured model consists of a star forming disk of radius 560 pc,
containing clumps of dense gas exposed to strong UV radiation, dominating the
emission of CO lines up to J=8. X-rays from the accreting supermassive black
hole in Mrk231 dominate the excitation and chemistry of the inner disk out to a
radius of 160 pc, consistent with the X-ray power of the AGN in Mrk231. The
extraordinary luminosity of the OH+ and H2O+ lines reveals the signature of
X-ray driven excitation and chemistry in this region.Comment: 5 pages, 2 figures, accepted for publication in Astronomy &
Astrophysics Special Issue on Herschel first result
Tracing star formation in galaxies with molecular line and continuum observations
We report our recent progress on extragalactic spectroscopic and continuum
observations, including HCN(J=1-0), HCO(J=1-0), and CN(N=1-0) imaging
surveys of local Seyfert and starburst galaxies using the Nobeyama Millimeter
Array, high-J CO observations (J=3-2 observations using the Atacama
Submillimeter Telescope Experiment (ASTE) and J=2-1 observations with the
Submillimeter Array) of galaxies, and 1.1 mm continuum observations
of high-z violent starburst galaxies using the bolometer camera AzTEC mounted
on ASTE.Comment: 6 pages, 5 figures, To appear in proceedings of "Far-Infrared and
Submillimeter Emission of the Interstellar Medium", EAS Publication Series,
Bad Honnef, November 2007, Eds. C. Kramer, S. Aalto, R. Simon. See
http://www.nro.nao.ac.jp/~f0212kk/FIR07/kk-ver20.pdf for a version with high
resolution figure
ALMA Observations of Warm Molecular Gas and Cold Dust in NGC 34
We present ALMA Cycle-0 observations of the CO (6-5) line emission
(rest-frame frequency = 691.473 GHz) and of the 435 dust continuum
emission in the nuclear region of NGC 34, a local luminous infrared galaxy
(LIRG) at a distance of 84 Mpc (1" = 407 pc) which contains a Seyfert 2 active
galactic nucleus (AGN) and a nuclear starburst. The CO emission is well
resolved by the ALMA beam (), with an integrated flux of
. Both the morphology
and kinematics of the CO (6-5) emission are rather regular, consistent with a
compact rotating disk with a size of 200 pc. A significant emission feature is
detected on the red-shifted wing of the line profile at the frequency of the
line, with an integrated flux of . However, it cannot be ruled out
that the feature is due to an outflow of warm dense gas with a mean velocity of
. The continuum is resolved into an elongated
configuration, and the observed flux corresponds to a dust mass of . An unresolved central core () contributes of the continuum flux and of
the CO (6-5) flux, consistent with insignificant contributions of the AGN to
both emissions. Both the CO (6-5) and continuum spatial distributions suggest a
very high gas column density () in the nuclear
region at .Comment: 10 pages, 13 figures, accepted for publication in Astrophysical
Journa
The post-AGB evolution of AGB mass loss variations
We present new numerical hydrodynamical modelling of the evolution of
Asymptotic Giant Branch (AGB) mass loss fluctuations during the
post-AGB/Planetary Nebula phase. These models show that after ionization, the
observable effects of the mass loss fluctuations disappear in a few thousand
years, consistent with the fact that only few PNe have been found to be
surrounded by `rings'. We derive the observational characteristics of these
rings, and compare them to reported observations of the rings around NGC 6543,
finding a good match of emission properties and line shapes. We predict small
variations in the observable electron temperatures.Comment: 12 pages, 13 figures, accepted by A&
ParIC : A Family of Parallel Incomplete Cholesky Preconditioners
A class of parallel incomplete factorization preconditionings
for the solution of large linear systems is investigated. The approach may
be regarded as a generalized domain decomposition method. Adjacent
subdomains have to communicate during the setting up of the precon
ditioner, and during the application of the preconditioner. Overlap is
not necessary to achieve high performance. Fillin levels are considered
in a global way. If necessary, the technique may be implemented as a
global reordering of the unknowns. Experimental results are reported
for twodimensional problems
ALMA Observations of Warm Dense Gas in NGC 1614 --- Breaking of Star Formation Law in the Central kpc
We present ALMA Cycle-0 observations of the CO (6-5) line emission and of the
435um dust continuum emission in the central kpc of NGC 1614, a local luminous
infrared galaxy (LIRG) at a distance of 67.8 Mpc (1 arcsec = 329 pc). The CO
emission is well resolved by the ALMA beam (0".26 x 0".20) into a
circum-nuclear ring, with an integrated flux of f_{CO(6-5)} = 898 (+-153) Jy
km/s, which is 63(+-12)% of the total CO(6-5) flux measured by Herschel. The
molecular ring, located between 100pc < r < 350pc from the nucleus, looks
clumpy and includes seven unresolved (or marginally resolved) knots with median
velocity dispersion of 40 km/s. These knots are associated with strong star
formation regions with \Sigma_{SFR} 100 M_\sun/yr/kpc^{2} and \Sigma_{Gas}
1.0E4 M_\sun/pc^{2}. The non-detections of the nucleus in both the CO (6-5)
line emission and the 435um continuum rule out, with relatively high
confidence, a Compton-thick AGN in NGC 1614. Comparisons with radio continuum
emission show a strong deviation from an expected local correlation between
\Sigma_{Gas} and \Sigma_{SFR}, indicating a breakdown of the Kennicutt-Schmidt
law on the linear scale of 100 pc.Comment: 13 pages, 10 figures; accepted by Ap
Development of the Surgical Patient safety Observation Tool (SPOT)
Background: A Surgical Patient safety Observation Tool (SPOT) was developed and tested in a multicentre observational pilot study. The tool enables monitoring and benchmarking perioperative safety performance across departments and hospitals, covering international patient safety goals. Methods: Nineteen perioperative patient safety observation topics were selected from Dutch perioperative patient safety guidelines, which also cover international patient safety goals. All items that measured these selected topics were then extracted from available local observation checklists of the participating hospitals. Experts individually prioritized the best measurement items per topic in an initial written Delphi round. The second (face to face) Delphi round resulted in consensus on the content of SPOT, after which the measurable elements (MEs) per topic were defined. Finally, the tool was piloted in eight hospitals for measurability, applicability, improvement potential, discriminatory capacity and feasibility. Results: The pilot test showed good measurability for all 19 patient safety topics (range of 8-291 MEs among topics), with good applicability (median 97 (range 11.8-100) per cent). The overall improvement potential appeared to be good (median 89 (range 72.5-100) per cent), and at topic level the tool showed good discriminatory capacity (variation 27.5 per cent, range in compliance 72.5-100 per cent). Overall scores showed relatively little variation between the participating hospitals (variation 13 per cent, range in compliance 83-96 per cent). All eight auditors considered SPOT a straightforward and easy-to-use tracer tool. Conclusion: A comprehensive tool to measure safety of care was developed and validated using a systematic, stepwise method, enabling hospitals to monitor, benchmark and improve perioperative safety performance
Herschel observations of water vapour in Markarian 231
The Ultra Luminous InfraRed Galaxy Mrk 231 reveals up to seven rotational
lines of water (H2O) in emission, including a very high-lying (E_{upper}=640 K)
line detected at a 4sigma level, within the Herschel/SPIRE wavelength range,
whereas PACS observations show one H2O line at 78 microns in absorption, as
found for other H2O lines previously detected by ISO. The absorption/emission
dichotomy is caused by the pumping of the rotational levels by far-infrared
radiation emitted by dust, and subsequent relaxation through lines at longer
wavelengths, which allows us to estimate both the column density of H2O and the
general characteristics of the underlying far-infrared continuum source.
Radiative transfer models including excitation through both absorption of
far-infrared radiation emitted by dust and collisions are used to calculate the
equilibrium level populations of H2O and the corresponding line fluxes. The
highest-lying H2O lines detected in emission, with levels at 300-640 K above
the ground state, indicate that the source of far-infrared radiation
responsible for the pumping is compact (radius=110-180 pc) and warm
(T_{dust}=85-95 K), accounting for at least 45% of the bolometric luminosity.
The high column density, N(H2O)~5x10^{17} cm^{-2}, found in this nuclear
component, is most probably the consequence of shocks/cosmic rays, an XDR
chemistry, and/or an "undepleted chemistry" where grain mantles are evaporated.
A more extended region, presumably the inner region of the 1-kpc disk observed
in other molecular species, could contribute to the flux observed in low-lying
H2O lines through dense hot cores, and/or shocks. The H2O 78 micron line
observed with PACS shows hints of a blue-shifted wing seen in absorption,
possibly indicating the occurrence of H2O in the prominent outflow detected in
OH (Fischer et al., this volume).Comment: 5 pages, 3 figure
Randomized clinical trial: Long-term Staphylococcus aureus decolonization in patients on home parenteral nutrition
Background & aims:
Staphylococcus aureus decolonization has proven successful in prevention of S. aureus infections and is a key strategy to maintain venous access and avoid hospitalization in patients receiving home parenteral nutrition (HPN). We aimed to determine the most effective and safe long-term S. aureus decolonization regimen.
Methods:
A randomized, open-label, multicenter clinical trial was conducted. Adult intestinal failure patients with HPN support and carrying S. aureus were randomly assigned to a ‘continuous suppression’ (CS) strategy, a repeated chronic topical antibiotic treatment or a ‘search and destroy’ (SD) strategy, a short and systemic antibiotic treatment. Primary outcome was the proportion of patients in whom S. aureus was totally eradicated during a 1-year period. Secondary outcomes included risk factors for decolonization failure and S. aureus infections, antimicrobial resistance, adverse events, patient compliance and cost-effectivity.
Results:
63 participants were included (CS 31; SD 32). The mean 1-year S. aureus decolonization rate was 61% (95% CI 44, 75) for the CS group and 39% (95% CI 25, 56) for the SD group with an OR of 2.38 (95% CI 0.92, 6.11, P = 0.07). More adverse effects occurred in the SD group (P = 0.01). Predictors for eradication failure were a S. aureus positive caregiver and presence of a (gastro)enterostomy.
Conclusion:
We did not demonstrate an increased efficacy of a short and systemic S. aureus decolonization strategy over a continuous topical suppression treatment. The latter may be the best option for HPN patients as it achieved a higher long-term decolonization rate and was well-tolerated (NCT03173053)
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