198 research outputs found
A search for the lenses in the Herschel Bright Sources (HerBS) sample
Verifying that sub-mm galaxies are gravitationally lensed requires time-expensive observations with oversubscribed high-resolution observatories. Here, we aim to strengthen the evidence of gravitational lensing within the Herschel Bright Sources (HerBS) by cross-comparing their positions to optical (SDSS) and near-infrared (VIKING) surveys, in order to search for the foreground lensing galaxy candidates. Resolved observations of the brightest HerBS sources have already shown that most are lensed, and a galaxy evolution model predicts that ∼76 per cent of the total HerBS sources are lensed, although with the SDSS survey we are only able to identify the likely foreground lenses for 25 per cent of the sources. With the near-infrared VIKING survey, however, we are able to identify the likely foreground lenses for 57 per cent of the sources, and we estimate that 82 per cent of the HerBS sources have lenses on the VIKING images even if we cannot identify the lens in every case. We find that the angular offsets between lens and Herschel source are larger than that expected if the lensing is done by individual galaxies. We also find that the fraction of HerBS sources that are lensed falls with decreasing 500-micron flux density, which is expected from the galaxy evolution model. Finally, we apply our statistical VIKING cross-identification to the entire Herschel-ATLAS catalogue, where we also find that the number of lensed sources falls with decreasing 500-micron flux density
The value of reasons for encounter in early detection of colorectal cancer
BACKGROUND:
Symptoms with a high predictive power for colorectal cancer (CRC) do not exist.
OBJECTIVE:
To explore the predictive value of patients' reason for encounter (RFE) in the two years prior to the diagnosis of CRC.
METHODS:
A retrospective nested case-control study using prospectively collected data from electronic records in general practice over 20 years. Matching was done based on age (within two years), gender and practice. The positive likelihood ratios (LR+) and odds ratios (OR) were calculated for RFE between cases and controls in the two years before the index date.
RESULTS:
We identified 184 CRC cases and matched 366 controls. Six RFEs had significant LR + and ORs for CRC, which may have high predictive power. These RFEs are part of four chapters in the International Classification of Primary Care (ICPC) that include tiredness (significant at 3-6 months prior to the diagnosis; LR+ 2.6 and OR 3.07; and from 0 to 3 months prior to the diagnosis; LR+ 2.0 and OR 2.36), anaemia (significant at three months before diagnosis; LR+ 9.8 and OR 16.54), abdominal pain, rectal bleeding and constipation (significant at 3-6 months before diagnosis; LR+ 3.0 and OR 3.33; 3 months prior to the diagnosis LR+ 8.0 and OR 18.10) and weight loss (significant at three months before diagnosis; LR+ 14.9 and OR 14.53).
CONCLUSION:
Data capture and organization in ICPC permits study of the predictive value of RFE for CRC in primary care
FLASH: Faint Lenses from Associated Selection with Herschel
We report the ALMA Band 7 observations of 86 Herschel sources that likely
contain gravitationally-lensed galaxies. These sources are selected with
relatively faint 500 m flux densities between 15 to 85 mJy in an effort to
characterize the effect of lensing across the entire million-source Herschel
catalogue. These lensed candidates were identified by their close proximity to
bright galaxies in the near-infrared VISTA Kilo-Degree Infrared Galaxy Survey
(VIKING) survey. Our high-resolution observations (0.15 arcsec) confirm 47 per
cent of the initial candidates as gravitational lenses, while lensing cannot be
excluded across the remaining sample. We find average lensing masses (log
M/M = 12.9 0.5) in line with previous experiments, although
direct observations might struggle to identify the most massive foreground
lenses across the remaining 53 per cent of the sample, particularly for lenses
with larger Einstein radii. Our observations confirm previous indications that
more lenses exist at low flux densities than expected from strong galaxy-galaxy
lensing models alone, where the excess is likely due to additional
contributions of cluster lenses and weak lensing. If we apply our method across
the total 660 sqr. deg. H-ATLAS field, it would allow us to robustly identify
3000 gravitational lenses across the 660 square degree Herschel ATLAS fields.Comment: Accepted for publication in MNRAS. Comments and discussion are
welcom
Molecular outflow in the reionization-epoch quasar J2054-0005 revealed by OH 119 m observations
Molecular outflows are expected to play a key role in galaxy evolution at
high redshift. To study the impact of outflows on star formation at the epoch
of reionization, we performed sensitive ALMA observations of OH 119 m
toward J2054-0005, a luminous quasar at . The OH line is detected and
exhibits a P-Cygni profile that can be fitted with a broad blue-shifted
absorption component, providing unambiguous evidence of an outflow, and an
emission component at near-systemic velocity. The mean and terminal outflow
velocities are estimated to be
and , respectively, making the molecular outflow in
this quasar one of the fastest at the epoch of reionization. The OH line is
marginally spatially resolved for the first time in a quasar at ,
revealing that the outflow extends over the central 2 kpc region. The mass
outflow rate is comparable to the star formation rate
(), indicating rapid
() quenching of star formation. The mass outflow rate in
a sample star-forming galaxies and quasars at exhibits a positive
correlation with the total infrared luminosity, although the scatter is large.
Owing to the high outflow velocity, a large fraction (up to ) of the
outflowing molecular gas may be able to escape from the host galaxy into the
intergalactic medium.Comment: Accepted to Ap
Identification of Large Equivalent Width Dusty Galaxies at 4 z 6 from Sub-mm Colours
Infrared (IR), sub-millimetre (sub-mm) and millimetre (mm) databases contain
a huge quantity of high quality data. However, a large part of these data are
photometric, and are thought not to be useful to derive a quantitative
information on the nebular emission of galaxies. The aim of this project is
first to identify galaxies at z > 4-6, and in the epoch of reionization from
their sub-mm colours. We also aim at showing that the colours can be used to
try and derive physical constraints from photometric bands, when accounting for
the contribution from the IR fine structure lines to these photometric bands.
We model the flux of IR fine structure lines with CLOUDY, and add them to the
dust continuum emission with CIGALE. Including or not emission lines in the
simulated spectral energy distribution (SED) modifies the broad band emission
and colours. The introduction of the lines allows to identify strong star
forming galaxies at z > 4 - 6 from the log10 (PSW_250um/PMW_350um) versus log10
(LABOCA_870um/PLW_500um) colour-colour diagramme. By comparing the relevant
models to each observed galaxy colour, we are able to roughly estimate the
fluxes of the lines, and the associated nebular parameters. This method allows
to identify a double sequence in a plot built from the ionization parameter and
the gas metallicity. The HII and photodissociation region (PDR) fine structure
lines are an essential part of the SEDs. It is important to add them when
modelling the spectra, especially at z > 4 - 6 where their equivalent widths
can be large. Conversely, we show that we can extract some information on
strong IR fine structure lines and on the physical parameters related to the
nebular emission from IR colour-colour diagrams.Comment: Paper accepted in Astronomy and Astrophysics on 10 November 202
Surgical treatment of childhood hepatoblastoma in the Netherlands (1990–2013)
Background: Achievement of complete surgical resection plays a key role in the successful treatment of children with hepatoblastoma. The aim of this study is to assess the surgical outcomes after partial liver resections for hepatoblastoma, focusing on postoperative complications, resection margins, 30-day mortality, and long-term survival. Method: Chart reviews were carried out on all patients treated for hepatoblastoma in the Netherlands between 1990 and 2013. Results: A total of 103 patients were included, of whom 94 underwent surgery. Partial hepatectomy was performed in 76 patients and 18 patients received a liver transplant as a primary procedure. In 42 of 73 (58 %) patients, one or more complications were reported. In 3 patients, information regarding complications was not available. Hemorrhage necessitating blood transfusion occurred in 33 (45 %) patients and 9 (12 %) patients developed biliary complications, of whom 8 needed one or more additional surgical interventions. Overall, 5-year disease-specific survival was 82, 92 % in the group of patients who underwent partial hepatectomy, and 77 % in the group of patients who underwent liver transplantation. Conclusions: Partial hepatectomy after chemotherapy in children with hepatoblastoma offers good chances of survival. This type of major surgery is associated with a high rate of surgical complications (58 %), which is not detrimental to survival
Erratum: The Herschel Bright Sources (HerBS): sample definition and SCUBA-2 observations
This is a correction to: Monthly Notices of the Royal Astronomical Society, Volume 473, Issue 2, January 2018, Pages 1751–1773, https://doi.org/10.1093/mnras/stx2267Instrumentatio
FLASH: Faint lenses from Associated Selection with <i>Herschel</i>
We report the ALMA Band 7 observations of 86 Herschel sources that likely contain gravitationally-lensed galaxies. These sources are selected with relatively faint 500 μm flux densities between 15 to 85 mJy in an effort to characterize the effect of lensing across the entire million-source Herschel catalogue. These lensed candidates were identified by their close proximity to bright galaxies in the near-infrared VISTA Kilo-Degree Infrared Galaxy Survey (VIKING) survey. Our high-resolution observations (0.15 arcsec) confirm 47 per cent of the initial candidates as gravitational lenses, while lensing cannot be excluded across the remaining sample. We find average lensing masses (log M/M⊙ = 12.9 ± 0.5) in line with previous experiments, although direct observations might struggle to identify the most massive foreground lenses across the remaining 53 per cent of the sample, particularly for lenses with larger Einstein radii. Our observations confirm previous indications that more lenses exist at low flux densities than expected from strong galaxy-galaxy lensing models alone, where the excess is likely due to additional contributions of cluster lenses and weak lensing. If we apply our method across the total 660 sqr. deg. H-ATLAS field, it would allow us to robustly identify 3000 gravitational lenses across the 660 square degree Herschel ATLAS fields
Detections of [C II] 158 m and [O III] 88 m in a Local Lyman Continuum Emitter, Mrk 54, and its Implications to High-redshift ALMA Studies
We present integral field, far-infrared (FIR) spectroscopy of Mrk 54, a local
Lyman Continuum Emitter (LCE), obtained with FIFI-LS on the Stratospheric
Observatory for Infrared Astronomy. This is only the second time, after Haro
11, that [C II] 158 m and [O III] 88 m spectroscopy of the known LCEs
have been obtained. We find that Mrk 54 has a strong [C II] emission that
accounts for % of the total FIR luminosity, whereas it has only moderate
[O III] emission, resulting in the low [O III]/[C II] luminosity ratio of
. In order to investigate whether [O III]/[C II] is a useful
tracer of (LyC escape fraction), we examine the correlations of
[O III]/[C II] and (i) the optical line ratio of [O III]
5007 \AA/[O II] 3727 \AA, (ii) specific star formation rate, (iii) [O III] 88
m/[O I] 63 m ratio, (iv) gas phase metallicity, and (v) dust
temperature based on a combined sample of Mrk 54 and the literature data from
the Herschel Dwarf Galaxy Survey and the LITTLE THINGS Survey. We find that
galaxies with high [O III]/[C II] luminosity ratios could be the result of high
ionization (traced by ), bursty star formation, high
ionized-to-neutral gas volume filling factors (traced by [O III] 88 m/[O
I] 63 m), and low gas-phase metallicities, which is in agreement with
theoretical predictions. We present an empirical relation between the [O
III]/[C II] ratio and based on the combination of the [O III]/[C
II] and correlation, and the known relation between
and . The relation implies that high-redshift galaxies with high
[O III]/[C II] ratios revealed by ALMA may have ,
significantly contributing to the cosmic reionization.Comment: 14 pages, 5 figures, Accepted for publication in Ap
First light demonstration of the integrated superconducting spectrometer
Ultra-wideband 3D imaging spectrometry in the millimeter-submillimeter
(mm-submm) band is an essential tool for uncovering the dust-enshrouded portion
of the cosmic history of star formation and galaxy evolution. However, it is
challenging to scale up conventional coherent heterodyne receivers or
free-space diffraction techniques to sufficient bandwidths (1 octave) and
numbers of spatial pixels (>). Here we present the design and first
astronomical spectra of an intrinsically scalable, integrated superconducting
spectrometer, which covers 332-377 GHz with a spectral resolution of . It combines the multiplexing advantage of microwave kinetic
inductance detectors (MKIDs) with planar superconducting filters for dispersing
the signal in a single, small superconducting integrated circuit. We
demonstrate the two key applications for an instrument of this type: as an
efficient redshift machine, and as a fast multi-line spectral mapper of
extended areas. The line detection sensitivity is in excellent agreement with
the instrument design and laboratory performance, reaching the atmospheric
foreground photon noise limit on sky. The design can be scaled to bandwidths in
excess of an octave, spectral resolution up to a few thousand and frequencies
up to 1.1 THz. The miniature chip footprint of a few
allows for compact multi-pixel spectral imagers, which would enable
spectroscopic direct imaging and large volume spectroscopic surveys that are
several orders of magnitude faster than what is currently possible.Comment: Published in Nature Astronomy. SharedIt Link to the full published
paper: https://rdcu.be/bM2F
- …