3,759 research outputs found
Constraining the properties of 1.2-mm dust clumps that contain luminous water masers
We have conducted a sensitive water maser search with the ATCA towards 267
1.2-mm dust clumps presented in the literature. We combine our new observations
with previous water maser observations to extend our sample to 294 1.2-mm dust
clumps, towards which we detect 165 distinct water maser sites towards 128
1.2-mm dust clumps. Within the fields of our observations, we additionally find
four water masers with no apparent associated 1.2-mm dust continuum emission.
Our overall detection rate of 44 per cent appears to vary as a function of
Galactic longitude. We find that there is an excellent correspondence between
the locations of the detected water masers with the peak of the target 1.2-mm
dust clump sources. As expected from previous similar studies, the water masers
are chiefly detected towards the bigger, brighter and more massive 1.2-mm dust
clumps. We find further evidence that the water masers tend to increase in flux
density (and therefore luminosity), as well as velocity range, as the sources
evolve. We also show that the current sample of water maser sources suffer less
from evolutionary biases than previous targeted searches. A higher fraction of
dust clump sources in our sample are only associated with water masers (41)
than only associated with methanol masers (13). This suggests that water masers
can be present at an even earlier evolutionary stage than 6.7-GHz methanol
masers. Comparison of the water maser detection rates associated with different
combinations of methanol maser and radio continuum, as well as those with
neither tracer, shows that the highest detection rate is towards those sources
which also exhibit methanol maser emission. We have tested a previously
hypothesised model for water maser presence towards 1.2-mm dust clumps. We
suggest refinements and future work which will further constrain the nature of
the driving sources associated with water masers.Comment: accepted to MNRA
DSM-5 non-suicidal self-injury disorder in a community sample: comparing NSSI engagement, recency and severity among emerging adults
Up to one in five emerging adults engage in non-suicidal self-injury (NSSI). Providing a better understanding of factors that differentiate between who engages in lifetime NSSI and who is more likely to engage in recent and clinically severe NSSI can provide meaningful information for prevention and intervention of NSSI. The present study (n = 669) considered NSSI lifetime engagement (no prior history of NSSI vs. lifetime NSSI), recency [past NSSI (>12 months ago) vs. recent (≤12-month) NSSI], and clinical severity among those with recent NSSI (subthreshold vs. DSM-5 NSSI disorder). The prevalence of NSSI disorder was 8.4% in emerging adults aged 18 to 26 years old. Higher anxiety levels were related to NSSI engagement, but only depressive symptoms and NSSI versatility were consistently associated with more recent NSSI and NSSI disorder. A stepped-care approach may be required in addressing NSSI among emerging adults
Flow in a Commercial Steel Pipe
Fully-developed turbulent flow in a commercial steel pipe is studied using single component hot-wire probes in both oneand two-point experiments. The streamwise turbulence component was measured over a Reynolds number range from 7.6Ă— 104 to 8.3Ă—106, covering the smooth to fully rough regimes. The experiments were conducted in the Princeton/ONR Superpipe facility that uses compressed air at pressures up to 200 atm as the working fluid. For Reynolds numbers less than about 8 Ă—105 the surface was hydraulically-smooth, and the results agreed closely with the smooth-wall turbulence intensity and spectral data obtained by Morrison et al. [10] and Zhao & Smits [14]. An assessment was performed of probe resolution and results indicate that the turbulence statistics of the large-scale motions were unaffected by the sensing wire length even at high Reynolds numbers. Transitionally-rough and fully-rough data showed deviation from the smooth-wall data as roughness effects became more prominent. In particular, the outer peak in the turbulence intensity observed at high Reynolds numbers in smooth pipe flow decreased in magnitude or stayed constant for transitionally rough and fully rough flow. The two-point azimuthal correlations were found to be consistent with the presence of very large scale coherent regions of low-wavenumber, low-momentum fluid observed in previous studies of wall-bounded flows. The correlations indicated that the azimuthal scale of these regions is Reynolds number independent
Supra-oscillatory critical temperature dependence of Nb-Ho bilayers
We investigate the critical temperature Tc of a thin s-wave superconductor
(Nb) proximity coupled to a helical rare earth ferromagnet (Ho). As a function
of the Ho layer thickness, we observe multiple oscillations of Tc superimposed
on a slow decay, that we attribute to the influence of the Ho on the Nb
proximity effect. Because of Ho inhomogeneous magnetization, singlet and
triplet pair correlations are present in the bilayers. We take both into
consideration when solving the self consistent Bogoliubov-de Gennes equations,
and we observe a reasonable agreement. We also observe non-trivial transitions
into the superconducting state, the zero resistance state being attained after
two successive transitions which appear to be associated with the magnetic
structure of Ho.Comment: Main article: 5 pages, 4 figures; Supplementary materials: 4 pages, 5
figure
Systematic effects and a new determination of the primordial abundance of 4He and dY/dZ from observations of blue compact galaxies
We use spectroscopic observations of a sample of 82 HII regions in 76 blue
compact galaxies to determine the primordial helium abundance Yp and the slope
dY/dZ from the Y-O/H linear regression. To improve the accuracy of the dY/dZ
measurement, we have included new spectrophotometric observations of 33 HII
regions which span a large metallicity range, with oxygen abundance 12+log(O/H)
varying between 7.43 and 8.30 (Zsun/30<Z<Zsun/4). For a subsample of 7 HII
regions, we derive the He mass fraction taking into account known systematic
effects, including collisional and fluorescent enhancements of HeI emission
lines, collisional excitation of hydrogen emission, underlying stellar HeI
absorption and the difference between the temperatures Te(HeII) in the He^+
zone and Te(OIII) derived from the collisionally excited [OIII] lines. We find
that the net result of all the systematic effects combined is small, changing
the He mass fraction by less than 0.6%. By extrapolating the Y vs. O/H linear
regression to O/H=0 for 7 HII regions of this subsample, we obtain
Yp=0.2421+/-0.0021 and dY/dO=5.7+/-1.8, which corresponds to dY/dZ=3.7+/-1.2,
assuming the oxygen mass fraction to be O=0.66Z. In the framework of the
standard Big Bang nucleosynthesis theory, this Yp corresponds to Omega_b h^2 =
0.012^+0.003_-0.002, where h is the Hubble constant in units of 100 km/s/Mpc.
This is smaller at the 2sigma level than the value obtained from recent
deuterium abundance and microwave background radiation measurements. The linear
regression slope dY/dO=4.3+/-0.7 (corresponding to dY/dZ=2.8+/-0.5) for the
whole sample of 82 HII regions is similar to that derived for the subsample of
7 HII regions, although it has a considerably smaller uncertainty.Comment: 53 pages, 3 Postscript figures, accepted for publication in the
Astrophysical Journa
Antenatal maternal anxiety is related to HPA-axis dysregulation and self-reported depressive symptoms in adolescence:A prospective study on the fetal origins of depressed moods
Very High Angular Resolution Science with the Square Kilometre Array
Preliminary specifications for the Square Kilometre Array (SKA) call for 25%
of the total collecting area of the dish array to be located at distances
greater than 180 km from the core, with a maximum baseline of at least 3000 km.
The array will provide angular resolution ~ 40 - 2 mas at 0.5 - 10 GHz with
image sensitivity reaching < 50 nJy/beam in an 8 hour integration with 500 MHz
bandwidth. Given these specifications, the high angular resolution component of
the SKA will be capable of detecting brightness temperatures < 200 K with
milliarcsecond-scale angular resolution. The aim of this article is to bring
together in one place a discussion of the broad range of new and important high
angular resolution science that will be enabled by the SKA, and in doing so,
address the merits of long baselines as part of the SKA. We highlight the fact
that high angular resolution requiring baselines greater than 1000 km provides
a rich science case with projects from many areas of astrophysics, including
important contributions to key SKA science.Comment: 13 pages, 6 figure
Local recurrence at the site of the Lone Star device through implantation of exfoliated cells during local excision for early rectal cancer:A case report
Introduction: Invasive procedures for colorectal cancer can cause iatrogenic tumor cell seeding. Implantation of these exfoliated cells in the surrounding tissue can result in locoregional cancer recurrence. This has been described in endoscopic procedures and major surgical resections, however recurrence in iatrogenic lesions of the anal canal during minimal invasive rectal surgery has not been shown in literature yet. This is the first reported case of recurrent rectal cancer that developed into an anal metastasis at the site where hooks of the Lone Star Retractor disrupted the epithelial lining of the anal canal during a local excision of early rectal cancer using TAMIS. Presentation of case: A 57 year old male was diagnosed with a high risk early stage rectal adenocarcinoma. He was treated with transanal minimally invasive surgery (TAMIS) with the use of a Lone Star retractor and he received subsequent chemo-radiotherapy. 23 months later the patient developed a bleeding mass bulging out of the anus. A true cut and incision biopsy was performed and the pathology report revealed localization of adenocarcinoma at the anal canal which was similar to the earlier diagnosed rectal carcinoma. The patient underwent an abdominal perineal resection and left-sided lymph node dissection. Discussion and conclusion: This shows that local recurrence through implantation of exfoliated tumor cells can occur in iatrogenic lesions of the anal canal not only in major but also in minimal invasive rectal surgery. Careful tissue handling and rectal washout may reduce the chance of this implantation metastasis.</p
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