1,171 research outputs found
Nuclear shell evolution and in-medium NN interaction
We report on a quantitative study of the evolution of the nuclear shell structure, in particular, effective single-particle energies (ESPEs), based on the spin-tensor decomposition of an effective two-body shell-model interaction. While the global trend of the ESPEs is mainly due to the central term of the effective interaction, variations of shell gaps invoke various components of the in-medium NN force. From a detailed analysis of a well-fitted realistic interaction in the sdpf shell-model space, two most important contributions for the evolution of the N = 20 and N = 28 shell gaps are confirmed to be the central term and the tensor term. The role of the latter is dominant to explain the energy shift of spin-orbit partners. Spin-tensor analysis of microscopic effective interactions in sd, pf, and gds shell-model spaces, contrasted with that of the phenomenologically adjusted ones, shows no evidence of amplification of the tensor component contribution; however, it points toward the neglect of three-body forces in the present microscopic interactions
The Circumstellar Disk Mass Distribution in the Orion Trapezium Cluster
We present the results of a submillimeter interferometric survey of
circumstellar disks in the Trapezium Cluster of Orion. We observed the 880
micron continuum emission from 55 disks using the Submillimeter Array, and
detected 28 disks above 3sigma significance with fluxes between 6-70 mJy and
rms noise between 0.7-5.3 mJy. Dust masses and upper limits are derived from
the submillimeter excess above free-free emission extrapolated from longer
wavelength observations. Above our completeness limit of 0.0084 solar masses,
the disk mass distribution is similar to that of Class II disks in
Taurus-Auriga and rho Ophiuchus but is truncated at 0.04 solar masses. We show
that the disk mass and radius distributions are consistent with the formation
of the Trapezium Cluster disks ~1 Myr ago and subsequent photoevaporation by
the ultraviolet radiation field from Theta-1 Ori C. The fraction of disks which
contain a minimum mass solar nebula within 60 AU radius is estimated to be
11-13% in both Taurus and the Trapezium Cluster, which suggests the potential
for forming Solar Systems is not compromised in this massive star forming
region.Comment: Accepted for publication in ApJL (2009 Feb 3
A Submillimeter Array Survey of Protoplanetary Disks in the Orion Nebula Cluster
We present the full results of our 3-year long Submillimeter Array survey of
protoplanetary disks in the Orion Nebula Cluster. We imaged 23 fields at 880
microns and 2 fields at 1330 microns, covering an area of ~6.5 arcmin^2 and
containing 67 disks. We detected 42 disks with fluxes between 6-135 mJy and at
rms noise levels between 0.6 to 5.3 mJy/beam. Thermal dust emission above any
free-free component was measured in 40 of the 42 detections, and the inferred
disk masses range from 0.003-0.07 Msolar. We find that disks located within 0.3
pc of theta^1 Ori C have a truncated mass distribution, while disks located
beyond 0.3 pc have masses more comparable to those found in low-mass star
forming regions. The disk mass distribution in Orion has a distance dependence,
with a derived relationship max(M_(disk)) = 0.046Msolar(d/0.3pc)^0.33 for the
maximum disk masses. We found evidence of grain growth in disk 197-427, the
only disk detected at both 880 microns and 1330 microns with the SMA. Despite
the rapid erosion of the outer parts of the Orion disks by photoevaporation,
the potential for planet formation remains high in this massive star forming
region, with approximately 18% of the surveyed disks having masses greater than
or equal to 0.01 Msolar within 60 AU.Comment: Accepted for publication in ApJ, 36 pages, 10 figure
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Closed-loop management of inpatient hyperglycemia.
The prevalence of diabetes in the hospital is increasing and approximately 18-20% of hospital beds are occupied by someone with diabetes [1]. Diabetes disproportionally affects the elderly, with three times greater prevalence in hospitalised people aged over 65 years than in those aged under 45 years [2]. Maintaining near normoglycaemia during hospital admissions can be very challenging. The impact of the current illness, medication changes, alterations to meal timings and intake, and requirement for nutrition support in hospital can all contribute to sub-optimal glucose control. Both hyper- and hypoglycemia in hospital are associated with increased risk of complications, length of stay, admission to the intensive care unit and mortality [3].Diabetes UK (#14/0004878), Swiss National Science Foundation (P1BEP3_165297) and European Foundation for the Study of Diabetes. Additional support for the Artificial Pancreas work by JDRF, National Institute for Health Research Cambridge Biomedical Research Centre and Wellcome Trust Strategic Award (100574/Z/12/Z)
Advance directives and the impact of timing. A qualitative study with Swiss general practitioners.
PRINCIPLES: Advance directives are seen as an important tool for documenting the wishes of patients who are no longer competent to make decisions in regards to their medical care. Due to their nature, approaching the subject of advance directives with a patient can be difficult for both the medical care provider and the patient. This paper focuses on general practitioners' perspectives regarding the timing at which this discussion should take place, as well as the advantages and disadvantages of the different moments.
METHODS: In 2013, 23 semi-structured face-to-face interviews were performed with Swiss general practitioners. Interviews were analysed using qualitative content analysis.
RESULTS: In our sample, 23 general practitioners provided different options that they felt were appropriate moments: either (a) when the patient is still healthy, (b) when illness becomes predominant, or (c) when a patient has been transferred to a long-term care facility. Furthermore, general practitioners reported uncertainty and discomfort regarding initiating the discussion.
CONCLUSION: The distinct approaches, perspectives and rationales show that there is no well-defined or "right" moment. However, participants often associated advance directives with death. This link caused discomfort and uncertainty, which led to hesitation and delay on the part of general practitioners. Therefore we recommend further training on how to professionally initiate a conversation about advance directives. Furthermore, based on our results and experience, we recommend an early approach with healthy patients paired with later regular updates as it seems to be the most effective way to inform patients about their end-of-life care options
An S-shaped outflow from IRAS 03256+3055 in NGC 1333
The IRAS source 03256+3055 in the NGC 1333 star forming region is associated
with extended sub-millimeter emission of complex morphology, showing multiple
clumps. One of these is found to coincide with the driving source of a bipolar
jet of S-shaped morphology seen in the emission lines of H_alpha and [SII] as
well as in the H2 emission lines in the K-band. Detailed images of the driving
source at the wavelengths of H_alpha and [SII] and in the I, J, H, and K bands
as well as a K-band spectrum and polarimetry are discussed. The near-infrared
morphology is characterized by a combination of line emission from the jet and
scattered light from a source with a steep continuum spectrum. The morphology
and proper motion of the jet are discussed in the context of a binary system
with a precessing disk. We conclude that the molecular core associated with
IRAS 03256+3055 consists of several clumps, only one of which shows evidence of
recent star formation at optical and near-infrared wavelengths.We also briefly
discuss a second, newly found near-infrared source associated with a compact
sub-millimeter continuum source near IRAS 03256+3055, and conclude that this
source may be physically unrelated the cluster of molecular clumps.Comment: 25 pages, including 5 figures. Accepted for publication in The
Astronomical Journa
ALMA Observations of the Largest Proto-Planetary Disk in the Orion Nebula, 114-426: A CO Silhouette
We present ALMA observations of the largest protoplanetary disk in the Orion
Nebula, 114-426. Detectable 345 GHz (856 micron) dust continuum is produced
only in the 350 AU central region of the ~1000 AU diameter silhouette seen
against the bright H-alpha background in HST images. Assuming optically thin
dust emission at 345 GHz, a gas-to-dust ratio of 100, and a grain temperature
of 20 K, the disk gas-mass is estimated to be 3.1 +/- 0.6 Jupiter masses. If
most solids and ices have have been incorporated into large grains, however,
this value is a lower limit. The disk is not detected in dense-gas tracers such
as HCO+ J=4-3, HCN J=4-3, or CS =7-6. These results may indicate that the
114-426 disk is evolved and depleted in some light organic compounds found in
molecular clouds. The CO J=3-2 line is seen in absorption against the bright 50
to 80 K background of the Orion A molecular cloud over the full spatial extent
and a little beyond the dust continuum emission. The CO absorption reaches a
depth of 27 K below the background CO emission at VLSR ~6.7 km/s about 0.52
arcseconds (210 AU) northeast and 12 K below the background CO emission at VLSR
~ 9.7 km/s about 0.34 arcseconds (140 AU) southwest of the suspected location
of the central star, implying that the embedded star has a mass less than 1
Solar mass .Comment: 20 pages, 4 figure
ALMA Observations of the Orion Proplyds
We present ALMA observations of protoplanetary disks ("proplyds") in the
Orion Nebula Cluster. We imaged 5 individual fields at 856um containing 22
HST-identified proplyds and detected 21 of them. Eight of those disks were
detected for the first time at submillimeter wavelengths, including the most
prominent, well-known proplyd in the entire Orion Nebula, 114-426. Thermal dust
emission in excess of any free-free component was measured in all but one of
the detected disks, and ranged between 1-163 mJy, with resulting disk masses of
0.3-79 Mjup. An additional 26 stars with no prior evidence of associated disks
in HST observations were also imaged within the 5 fields, but only 2 were
detected. The disk mass upper limits for the undetected targets, which include
OB stars, theta1Ori C and theta1Ori F, range from 0.1-0.6 Mjup. Combining these
ALMA data with previous SMA observations, we find a lack of massive (>3 Mjup)
disks in the extreme-UV dominated region of Orion, within 0.03 pc of O-star
theta1Ori C. At larger separations from theta1Ori C, in the far-UV dominated
region, there is a wide range of disk masses, similar to what is found in
low-mass star forming regions. Taken together, these results suggest that a
rapid dissipation of disk masses likely inhibits potential planet formation in
the extreme-UV dominated regions of OB associations, but leaves disks in the
far-UV dominated regions relatively unaffected.Comment: ApJ, in pres
ALMA Observations of Asymmetric Molecular Gas Emission from a Protoplanetary Disk in the Orion Nebula
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations
of molecular line emission from d216-0939, one of the largest and most massive
protoplanetary disks in the Orion Nebula Cluster (ONC). We model the spectrally
resolved HCO (4--3), CO (3--2), and HCN (4--3) lines observed at 0\farcs5
resolution to fit the temperature and density structure of the disk. We also
weakly detect and spectrally resolve the CS (7--6) line but do not model it.
The abundances we derive for CO and HCO are generally consistent with
expected values from chemical modeling of protoplanetary disks, while the HCN
abundance is higher than expected. We dynamically measure the mass of the
central star to be which is inconsistent with the
previously determined spectral type of K5. We also report the detection of a
spatially unresolved high-velocity blue-shifted excess emission feature with a
measurable positional offset from the central star, consistent with a Keplerian
orbit at . Using the integrated flux of the feature in
HCO (4--3), we estimate the total H gas mass of this feature to be at
least , depending on the assumed temperature. The
feature is due to a local temperature and/or density enhancement consistent
with either a hydrodynamic vortex or the expected signature of the envelope of
a forming protoplanet within the disk.Comment: 19 pages, 12 figures, accepted for publication in A
Discovery of X rays from Class 0 protostar candidates in OMC-3
We have observed the Orion Molecular Clouds 2 and 3 (OMC-2 and OMC-3) with
the Chandra X-ray Observatory (CXO). The northern part of OMC-3 is found to be
particularly rich in new X-ray features; four hard X-ray sources are located in
and along the filament of cloud cores. Two sources coincide positionally with
the sub- dust condensations of MMS 2 and 3 or an outflow radio source
VLA 1, which are in a very early phase of star formation. The X-ray spectra of
these sources show an absorption column of (1-3) x 10^23 H cm-2. Assuming a
moderate temperature plasma, the X-ray luminosity in the 0.5-10 keV band is
estimated to be ~10^30 erg s^-1 at a distance of 450 pc. From the large
absorption, positional coincidence and moderate luminosity, we infer that the
hard X-rays are coming from very young stellar objects embedded in the
molecular cloud cores. We found another hard X-ray source near the edge of the
dust filament. The extremely high absorption of 3 x 10^23 H cm^-2 indicates
that the source must be surrounded by dense gas, suggesting that it is either a
YSO in an early accretion phase or a Type II AGN (e.g. a Seyfert 2), although
no counterpart is found at any other wavelength. In contrast to the hard X-ray
sources, soft X-ray sources are found spread around the dust filaments, most of
which are identified with IR sources in the T Tauri phase.Comment: 9 pages, To be appeared in ApJ v554 n2 Jun 20, 2001 issue, related
press release is available at http://science.psu.edu/alert/Tsuboi11-2000.htm,
Figure 1 and figure 2 with the best resolution is available at
ftp.astro.psu.edu/pub/tsuboi/OMC/010205
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