1,548 research outputs found
The significance of SNODENT
SNODENT is a dental diagnostic vocabulary incompletely integrated in SNOMED-CT. Nevertheless, SNODENT could become the de facto standard for dental diagnostic coding. SNODENT's manageable size, the fact that it is administratively self-contained, and relates to a well-understood domain provides valuable opportunities to formulate and test, in controlled experiments, a series of hypothesis concerning diagnostic systems. Of particular interest are questions related to establishing appropriate quality assurance methods for its optimal level of detail in content, its ontological structure, its construction and maintenance. This paper builds on previousâsoftware-based methodologies designed to assess the quality of SNOMED-CT. When applied to SNODENT several deficiencies were uncovered. 9.52% of SNODENT terms point to concepts in SNOMED-CT that have some problem. 18.53% of SNODENT terms point to SNOMED-CT concepts do not have, in SNOMED, the term used by SNODENT. Other findings include the absence of a clear specification of the exact relationship between a term and a termcode in SNODENT and the improper assignment of the same termcode to terms with significantly different meanings. An analysis of the way in which SNODENT is structurally integrated into SNOMED resulted in the generation of 1081 new termcodes reflecting entities not present in the SNOMED tables but required by SNOMED's own description logic based classification principles. Our results show that SNODENT requires considerable enhancements in content, quality of coding, quality of ontological structure and the manner in which it is integrated and aligned with SNOMED. We believe that methods for the analysis of the quality of diagnostic coding systems must be developed and employed if such systems are to be used effectively in both clinical practice and clinical research
Spatially Resolved Spectroscopy of Sub-AU-Sized Regions of T Tauri and Herbig Ae/Be Disks
We present spatially resolved near-IR spectroscopic observations of 15 young
stars. Using a grism spectrometer behind the Keck Interferometer, we obtained
an angular resolution of a few milli-arcseconds and a spectral resolution of
230, enabling probes of both gas and dust in the inner disks surrounding the
target stars. We find that the angular size of the near-IR emission typically
increases with wavelength, indicating hot, presumably gaseous material within
the dust sublimation radius. Our data also clearly indicate Brackett-gamma
emission arising from hot hydrogen gas, and suggest the presence of water vapor
and carbon monoxide gas in the inner disks of several objects. This gaseous
emission is more compact than the dust continuum emission in all cases. We
construct simple physical models of the inner disk and fit them to our data to
constrain the spatial distribution and temperature of dust and gas emission
components.Comment: 40 pages, 8 figures. Accepted for publication in Ap
Characterizing the IYJ Excess Continuum Emission in T Tauri Stars
We present the first characterization of the excess continuum emission of
accreting T Tauri stars between optical and near-infrared wavelengths. With
nearly simultaneous spectra from 0.48 to 2.4 microns acquired with HIRES and
NIRSPEC on Keck and SpeX on the IRTF, we find significant excess continuum
emission throughout this region, including the I, Y, and J bands, which are
usually thought to diagnose primarily photospheric emission. The IYJ excess
correlates with the excess in the V band, attributed to accretion shocks in the
photosphere, and the excess in the K band, attributed to dust in the inner disk
near the dust sublimation radius, but it is too large to be an extension of the
excess from these sources. The spectrum of the excess emission is broad and
featureless, suggestive of blackbody radiation with a temperature between 2200
and 5000 K. The luminosity of the IYJ excess is comparable to the accretion
luminosity inferred from modeling the blue and ultraviolet excess emission and
may require reassessment of disk accretion rates. The source of the IYJ excess
is unclear. In stars of low accretion rate, the size of the emitting region is
consistent with cooler material surrounding small hot accretion spots in the
photosphere. However, for stars with high accretion rates, the projected area
is comparable to or exceeds that of the stellar surface. We suggest that at
least some of the IYJ excess emission arises in the dust-free gas inside the
dust sublimation radius in the disk.Comment: Accepted to ApJ, 31 pages, 21 figure
Teaching webside manner: development and initial evaluation of a video consultation skills training module for undergraduate medical students
Background Video consultations are increasingly used to communicate with patients, particularly during the current COVID-19 pandemic. However, training in video consultation skills receives scant attention in the literature. We sought to introduce this important topic to our undergraduate medical school curriculum. Objective To increase final year medical studentsâ video consultation skills and knowledge. Methods We used Plan, Do, Study, Act (PDSA) quality improvement methodology with a pre-post study design to develop a teaching session for 5th year medical students, informed by a literature review and online clinician survey. The 2 hour session comprised an introduction and three practical stations: patient selection and ethics, technology and example videos, and simulation. Subjective pre- and post-session confidence was reported by students across seven domains using 5-point scales (1: not at all confident; 5: extremely confident). Students and facilitators completed post-session feedback forms. Results The 40 students and 3 facilitators who attended, over two separate teaching sessions, provided unanimously positive feedback. All students considered the session relevant. Subjective confidence ratings (n = 34) significantly increased from pre- to post-session (mean increase 1.78, p < 0.001). Conclusions The inaugural teaching session was well-received and subjective assessment measures showed improvement in taught skills. This pilot has informed a UK-wide multi-centre study with subjective and objective data collection
A Taxonomy of Internet Appliances
The world is evolving from one in which almost all access to the Internet comes from personal
computers (PCs) to one in which so-called Internet appliances (IAs) will make up a greater share
of end-user equipment. Today's PC is a general-purpose, highly configurable and extensible
device ? an "intelligent end-node" of the sort the Internet's designers had in mind. As such, it
allows users much freedom of choice (such as which service provider to use, which Web sites to
visit, and which new software to download) in exchange for dealing with associated complexity.
An IA is a device connected to the Internet, but beyond that there is little consensus on
functionality and target markets. There is, however, general agreement that it reduces the level
of complexity seen by the user. A variety of approaches to reducing complexity are being
pursued. These fall on a spectrum from totally fixing the function of devices, to automating the
configuration of more general purpose systems. In the middle are devices whose functions
appear more or less fixed to the user, but which retain some limited capability for upgrade
through their Internet connection
High Resolution K-band Spectroscopy of MWC 480 and V1331 Cyg
We present high resolution (R=25,000-35,000) K-band spectroscopy of two young
stars, MWC 480 and V1331 Cyg. Earlier spectrally dispersed (R=230)
interferometric observations of MWC 480 indicated the presence of an excess
continuum emission interior to the dust sublimation radius, with a spectral
shape that was interpreted as evidence for hot water emission from the inner
disk of MWC 480. Our spectrum of V1331 Cyg reveals strong emission from CO and
hot water vapor, likely arising in a circumstellar disk. In comparison, our
spectrum of MWC 480 appears mostly featureless. We discuss possible ways in
which strong water emission from MWC 480 might go undetected in our data. If
strong water emission is in fact absent from the inner disk, as our data
suggest, the continuum excess interior to the dust sublimation radius that is
detected in the interferometric data must have another origin. We discuss
possible physical origins for the continuum excess.Comment: 29 pages, 5 figures, to appear in Ap
Protoplanetary Disk Masses in the Young NGC 2024 Cluster
We present the results from a Submillimeter Array survey of the 887 micron
continuum emission from the protoplanetary disks around 95 young stars in the
young cluster NGC 2024. Emission was detected from 22 infrared sources, with
flux densities from ~5 to 330 mJy; upper limits (at 3sigma) for the other 73
sources range from 3 to 24 mJy. For standard assumptions, the corresponding
disk masses range from ~0.003 to 0.2Msolar, with upper limits at
0.002--0.01Msolar. The NGC 2024 sample has a slightly more populated tail at
the high end of its disk mass distribution compared to other clusters, but
without more information on the nature of the sample hosts it remains unclear
if this difference is statistically significant or a superficial selection
effect. Unlike in the Orion Trapezium, there is no evidence for a disk mass
dependence on the (projected) separation from the massive star IRS2b in the NGC
2024 cluster. We suggest that this is due to either the cluster youth or a
comparatively weaker photoionizing radiation field.Comment: ApJ, in pres
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
Massive Protoplanetary Disks in the Trapezium Region
(abridged) We determine the disk mass distribution around 336 stars in the
young Orion Nebula cluster by imaging a 2.5' x 2.5' region in 3 mm continuum
emission with the Owens Valley Millimeter Array. For this sample of 336 stars,
we observe 3 mm emission above the 3-sigma noise level toward ten sources, six
of which have also been detected optically in silhouette against the bright
nebular background. In addition, we detect 20 objects that do not correspond to
known near-IR cluster members. Comparisons of our measured fluxes with longer
wavelength observations enable rough separation of dust emission from thermal
free-free emission, and we find substantial dust emission toward most objects.
For the ten objects detected at both 3 mm and near-IR wavelengths, eight
exhibit substantial dust emission. Excluding the high-mass stars and assuming a
gas-to-dust ratio of 100, we estimate circumstellar masses ranging from 0.13 to
0.39 Msun. For the cluster members not detected at 3 mm, images of individual
objects are stacked to constrain the mean 3 mm flux of the ensemble. The
average flux is detected at the 3-sigma confidence level, and implies an
average disk mass of 0.005 Msun, comparable to the minimum mass solar nebula.
The percentage of stars in Orion surrounded by disks more massive than ~0.1
Msun is consistent with the disk mass distribution in Taurus, and we argue that
massive disks in Orion do not appear to be truncated through close encounters
with high-mass stars. Comparison of the average disk mass and number of massive
dusty structures in Orion with similar surveys of the NGC 2024 and IC 348
clusters constrains the evolutionary timescales of massive circumstellar disks
in clustered environments.Comment: 27 pages, including 7 figures. Accepted by Ap
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