4,205 research outputs found
WSRT and VLA Observations of the 6 cm and 2 cm lines of H2CO in the direction of W 58 C1(ON3) and W 58 C2
Absorption in the J{K-K+} = 2{11}-2{12} transition of formaldehyde at 2 cm
towards the ultracompact HII regions C1 and C2 of W 58 has been observed with
the VLA with an angular resolution of ~0.2'' and a velocity resolution of ~1
km/s. The high resolution continuum image of C1 (ON 3) shows a partial shell
which opens to the NE. Strong H2CO absorption is observed against W 58 C1. The
highest optical depth (tau > 2) occurs in the SW portion of C1 near the edge of
the shell, close to the continuum peak. The absorption is weaker towards the
nearby, more diffuse compact HII region C2, tau<~0.3. The H2CO velocity (-21.2
km/s) towards C1 is constant and agrees with the velocity of CO emission,
mainline OH masers, and the H76 alpha recombination line, but differs from the
velocity of the 1720 MHz OH maser emission (~-13 km/s). Observations of the
absorption in the J{K-K+} = 1{10}-1{11} transition of formaldehyde at 6 cm
towards W 58 C1 and C2 carried out earlier with the WSRT at lower resolution
(~4''x7'') show comparable optical depths and velocities to those observed at 2
cm. Based on the mean optical depth profiles at 6 cm and 2 cm, the volume
density of molecular hydrogen n(H2) and the formaldehyde column density N(H2CO)
were determined. The n(H2) is ~6E4 /cm**3 towards C1. N(H2CO) for C1 is ~8E14
/cm**2 while that towards C2 is ~8E13 /cm**2.Comment: AJ in press Jan 2001, 14 pages plus 6 figures (but Fig. 1 has 4
separate parts, a through d). Data are available at
http://adil.ncsa.uiuc.edu/document/00.HD.0
VLA observations of candidate high-mass protostellar objects at 7 mm
We present radio continuum observations at 7 mm made using the Very Large
Array towards three massive star forming regions thought to be in very early
stages of evolution selected from the sample of Sridharan et al. (2002).
Emission was detected towards all three sources (IRAS 18470-0044, IRAS
19217+1651 and IRAS 23151+5912). We find that in all cases the 7 mm emission
corresponds to thermal emission from ionized gas. The regions of ionized gas
associated with IRAS 19217+1651 and IRAS 23151+5912 are hypercompact with
diameters of 0.009 and 0.0006 pc, and emission measures of 7.0 x 10^8 and 2.3 x
10^9 pc cm^(-6), respectively.Comment: 17 pages, 5 figures, accepted by The Astronomical Journa
A search for hypercompact HII regions in the Galactic Plane
22 pages, 8 figures, 6 tables, accepted by MNRASWe have carried out the largest and most unbiased search for hypercompact (HC) H II regions. Our method combines four interferometric radio continuum surveys (THOR, CORNISH, MAGPIS, and White2005) with far-infrared and sub-mm Galactic Plane surveys to identify embedded H II regions with positive spectral indices; 120 positive spectrum H II regions have been identified from a total sample of 534 positive spectral index radio sources. None of these H II regions, including the known HC H II regions recovered in our search, fulfills the canonical definition of an HC H II region at 5 GHz. We suggest that the current canonical definition of HC H II regions is not accurate and should be revised to include a hierarchical structure of ionized gas that results in an extended morphology at 5 GHz. Correlating our search with known ultracompact (UC) H II region surveys, we find that roughly half of detected UC H II regions have positive spectral indices, instead of more commonly assumed flat and optically thin spectra. This implies a mix of optically thin and thick emission and has important implications for previous analyses which have so far assumed optically thin emission for these objects. Positive spectrum H II regions are statistically more luminous and possess higher Lyman continuum fluxes than H II regions with flat or negative indices. Positive spectrum H II regions are thus more likely to be associated with more luminous and massive stars. No differences are found in clump mass, linear diameter, or luminosity-to-mass ratio between positive spectrum and non-positive spectrum H II regions.Peer reviewedFinal Accepted Versio
Expansion of W 3(OH)
A direct measurement of the expansion of W 3(OH) is made by comparing Very
Large Array images taken about 10 yr apart. The expansion is anisotropic with a
typical speed of 3 to 5 km/s, indicating a dynamical age of only 2300 yr. These
observations are inconsistent with either the freely expanding shell model or a
simple bow shock model. The most favored model is a slowly expanding shell-like
HII region, with either a fast rarefied flow or another less massive diffuse
ionized region moving towards the observer. There is also a rapidly evolving
source near the projected center of emission, perhaps related to the central
star.Comment: LaTeX file, 28 pages, includes 8 figures. To appear in ApJ in
December 10 (1998) issue. Also available at
http://www.submm.caltech.edu/~kawamura/w3oh_pp.p
Origin and possible birthplace of the extreme runaway star HIP 60350
Using the recently determined spatial velocity components of the extreme
runaway star HIP 60350 and a gravitation potential model of the Galaxy, we
integrate the orbit of HIP 60350 back to the plane of the Galaxy. In this way,
a possible location of the formation of the star is determined. We estimate the
uncertainty of the result due to the uncertainties of the gravitational
potential model and the errors in the spatial velocity components. The place of
birth lies (within the errors) near the position of the open cluster NGC 3603.
However, the ejection event which occured about 20 Myr ago is in contradiction
with the cluster mean age of 3-4 Myr. We suggest that it occured at an earlier
phase in sequential star formation in that region. We discuss also ejection
mechanisms. Due to the rather high mass of the star (about 5 \Msol), the most
probable model is that of dynamical ejection.Comment: Astron. Astrophys. submitted, 7 pages, 5 eps figure
Radio Continuum and Recombination Line Study of UC HII Regions with Extended Envelopes
We have carried out 21 cm radio continuum observations of 16 UC HII regions
using the VLA (D-array) in search of associated extended emission. We have also
observed H76 recombination line towards all the sources and
He76 line at the positions with strong H76 line emission. The
UC HII regions have simple morphologies and large (>10) ratios of single-dish
to VLA fluxes. Extended emission was detected towards all the sources. The
extended emission consists of one to several compact components and a diffuse
extended envelope. All the UC HII regions but two are located in the compact
components, where the UC HII regions always correspond to their peaks. The
compact components with UC HII regions are usually smaller and denser than
those without UC HII regions. Our recombination line observations indicate that
the ultracompact, compact, and extended components are physically associated.
The UC HII regions and their associated compact components are likely to be
ionized by the same sources on the basis of the morphological relations
mentioned above. This suggests that almost all of the observed UC HII regions
are not `real' UC HII regions and that their actual ages are much greater than
their dynamical age (<10000 yr). We find that most of simple UC HII regions
previously known have large ratios of single-dish to VLA fluxes, similar to our
sources. Therefore, the `age problem' of UC HII regions does not seem to be as
serious as earlier studies argued. We present a simple model that explains
extended emission around UC HII regions. Some individual sources are discussed.Comment: 29 pages, 28 postscript figures, Accepted for publication in Ap
Recurrence of hepatitis C virus during leucocytopenia and spontaneous clearance after recovery from cytopenia: a case report
<p>Abstract</p> <p>Introduction</p> <p>There is little information about the risk of HCV recurrence in immunosuppressed patients. Although the presence of antibodies to HCV and the absence of HCV-RNA is usually considered to indicate viral elimination, the virus may not be completely eliminated but may be under control of an effective immune response.</p> <p>Case presentation</p> <p>A 69 year old man presented with jaundice, elevated ALT, AST, lipase and concomitant abdominal pain. He was found to be positive for HCV-RNA (genotype 3a) and was diagnosed with acute hepatitis C. Six weeks later no HCV-RNA was detected, and the patient was diagnosed with hyperthyreosis and started on propylthiouracil. After 4 weeks of propylthiouracil treatment, the patient developed leucocytopenia, followed by liver function deterioration and reappearance of HCV-RNA. Propylthiouracil was discontinued and his leukocyte counts increased. Twenty-eight weeks after onset of acute hepatitis C, no HCV-RNA was detected.</p> <p>Conclusion</p> <p>This case history shows the risk of recurrence of HCV during leucocytopenia. These findings indicate that patients who are anti-HCV positive but HCV-RNA negative may be at risk of cytopenia-induced HCV reactivation.</p
Theology, News and Notes - Vol. 43, No. 05
Theology News & Notes was a theological journal published by Fuller Theological Seminary from 1954 through 2014.https://digitalcommons.fuller.edu/tnn/1128/thumbnail.jp
OT FE-Box Test Procedures
The OT FE readout requirements is the precise (~0.5 ns) and efficient drift time measurement at an occupancy of ~4% to ensure single hit resolution. The acquired achievement of such performance on an assembled FE-Box is verify through a final test performed using a special FE-Tester. In this note the test procedures are described
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