659 research outputs found
Can the appropriateness of eye care be measured through cross-sectional retrospective patient record review in eye care practices in Australia? the icaretrack feasibility study
© Author(s) (or their employer(s)) 2018. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ. Objectives The CareTrack study found that a wide range of appropriateness of care (ie, care in line with evidence-based or consensus-based guidelines) was delivered across many health conditions in Australia. This study therefore aimed to demonstrate the feasibility of using the CareTrack method (a retrospective onsite record review) to measure the appropriateness of eye care delivery. Design Cross-sectional feasibility study. Setting and participants Two hundred and thirteen patient records randomly selected from eight optometry and ophthalmology practices in Australia, selected through a combination of convenience and maximum variation sampling. Methods Retrospective record review designed to assess the alignment between eye care delivered and 93 clinical indicators (Delphi method involving 11 experts) extracted from evidence-based clinical practice guidelines. Primary outcome measure Number of eligible patient records, sampling rates and data collection time. This feasibility study also tested the ability of 93 clinical indicators to measure percentage appropriate eye care for preventative, glaucoma and diabetic eye care. A secondary outcome was the percentage of practitioner-patient encounters at which appropriate eye care was received. Results A median of 20 records (range 9 to 63) per practice were reviewed. Data collection time ranged from 3 to 5.5 hours (median 3.5). The most effective sampling strategy involved random letter generation followed by sequential sampling. The appropriateness of care was 69% (95% CI 67% to 70%) for preventative eye care, 60% (95% CI 56% to 58%) for glaucoma and 63% (95% CI 57% to 69%) for diabetic eye care. Conclusions Appropriateness of eye care can be measured effectively using retrospective record review of eye care practices and consensus-based care indicators
The GREAT triggerless total data readout method
Recoil decay tagging (RDT) is a very powerful method for the spectroscopy of exotic nuclei. RDT is a delayed coincidence technique between detectors usually at the target position and at the focal plane of a spectrometer. Such measurements are often limited by dead time. This paper describes a novel triggerless data acquisition method, which is being developed for the Gamma Recoil Electron Alpha Tagging (GREAT) spectrometer, that overcomes this limitation by virtually eliminating dead time. Our solution is a total data readout (TDR) method where all channels run independently and are associated in software to reconstruct events. The TDR method allows all the data from both target position and focal plane to be collected with practically no dead-time losses. Each data word is associated with a timestamp generated from a global 100-MHz clock. Events are then reconstructed in real time in the event builder using temporal and spatial associations defined by the physics of the experimen
The deuterium-to-oxygen ratio in the interstellar medium
Because the ionization balances for HI, OI, and DI are locked together by
charge exchange, D/O is an important tracer for the value of the D/H ratio and
for potential spatial variations in the ratio. As the DI and OI column
densities are of similar orders of magnitude for a given sight line,
comparisons of the two values will generally be less subject to systematic
errors than comparisons of DI and HI, which differ by about five orders of
magnitude. Moreover, D/O is additionally sensitive to astration, because as
stars destroy deuterium, they should produce oxygen. We report here the results
of a survey of D/O in the interstellar medium performed with FUSE. We also
compare these results with those for D/N. Together with a few results from
previous missions, the sample totals 24 lines of sight. The distances range
from a few pc to ~2000 pc and log N(DI) from ~13 to ~16 (cm-2). The D/O ratio
is constant in the local interstellar medium out to distances of ~150 pc and
N(DI) ~ 1x10^15 cm-2, i.e. within the Local Bubble. In this region of the
interstellar space, we find D/O = (3.84+/-0.16)x10^-2 (1 sigma in the mean).
The homogeneity of the local D/O measurements shows that the spatial variations
in the local D/H and O/H must be extremely small, if any. A comparison of the
Local Bubble mean value with the few D/O measurements available for low
metallicity quasar sight lines shows that the D/O ratio decreases with cosmic
evolution, as expected. Beyond the Local Bubble we detected significant spatial
variations in the value of D/O. This likely implies a variation in D/H, as O/H
is known to not vary significantly over the distances covered in this study.
Our dataset suggests a present-epoch deuterium abundance below 1x10^-5, i.e.
lower than the value usually assumed, around 1.5x10^-5.Comment: 17 pages, 9 figures, 4 tables, accepted for publication in the
Astrophysical Journa
Light Element Abundances From z=0 To z=5
Plausible ratios of deuterium to hydrogen D/H as a function of metallicity,
time, and redshift are investigated. Guided by the heavy element abundance
patterns observed locally in Galactic dwarf stars and at large redshift in
quasi-stellar object absorption line systems, empirical evolution of the
relative abundance ratios Li/D, B/D, N/D, O/D, and F/D for QSO absorption line
systems are given for the possible evolutionary patterns in D/H. Shortened
abstract.Comment: 30 pages including 8 figures, ApJ in pres
IMAPS Observations of Interstellar Neutral Argon and the Implications for Partially Ionized Gas
We use the absorption features from neutral argon at 1048 and 1066 A to
determine interstellar abundances or their lower limits toward nine early-type
stars. These features were observed with the Interstellar Medium Absorption
Profile Spectrograph (IMAPS) along sight lines with low reddening and low
fractional abundances of molecular hydrogen. We find that the interstellar Ar I
is below its solar and B-star abundance with respect to hydrogen toward zeta
Pup, gamma2 Vel and beta Cen A with (logarithmic) reduction factors
-0.37+/-0.09, -0.18+/-0.10, and -0.61+/-0.12 dex, respectively.
While Ar can condense onto the surfaces of dust grains in the interiors of
dense clouds, it is unlikely that argon atoms are depleted by this process in
the low-density lines of sight considered in this study. Instead, we propose
that the relatively large photoionization cross section of Ar makes it much
easier to hide in its ionized form than H. In regions that are about half
ionized, this effect can lower Ar I/H I by -0.11 to -0.96 dex, depending on the
energy of the photoionizing radiation and its intensity divided by the local
electron density. We apply this interpretation for the condition of the gas in
front of beta Cen A, which shows the largest deficiency of Ar. Also, we
determine the expected magnitudes of the differential ionizations for He, N, O,
Ne and Ar in the partly ionized, warm gas in the local cloud around our solar
system. For the local cloud and others that can be probed by UV studies, the
observed Ar I to H I ratio may be a good discriminant between two possible
alternatives, collisional ionization or photoionization, for explaining the
existence of partly ionized regions.Comment: 36 pages, 3 figure
High Resolution HST-STIS Spectra of CI and CO in the Beta Pictoris Circumstellar Disk
High resolution FUV echelle spectra showing absorption features arising from
CI and CO gas in the Beta Pictoris circumstellar (CS) disk were obtained on
1997 December 6 and 19 using the Space Telescope Imaging Spectrograph (STIS).
An unsaturated spin-forbidden line of CI at 1613.376 A not previously seen in
spectra of Beta Pictoris was detected, allowing for an improved determination
of the column density of CI at zero velocity relative to the star (the stable
component), N = (2-4) x 10^{16} cm^{-2}. Variable components with multiple
velocities, which are the signatures of infalling bodies in the Beta Pictoris
CS disk, are observed in the CI 1561 A and 1657 A multiplets. Also seen for the
first time were two lines arising from the metastable singlet D level of
carbon, at 1931 A and 1463 A The results of analysis of the CO A-X (0-0),
(1-0), and (2-0) bands are presented, including the bands arising from {13}^CO,
with much better precision than has previously been possible, due to the very
high resolution provided by the STIS echelle gratings. Only stable CO gas is
observed, with a column density N(CO) = (6.3 +/- 0.3) x 10^{14} cm{-2}. An
unusual ratio of the column densities of {12}^CO to {13}^CO is found (R = 15
+/- 2). The large difference between the column densities of CI and CO
indicates that photodissociation of CO is not the primary source of CI gas in
the disk, contrary to previous suggestion.Comment: 13 pages, including 6 figures. LaTex2e (emulateapj5.sty). Accepted
for publication in Ap
Magnetic record of deglaciation using FORC-PCA, sortable-silt grain size, and magnetic excursion at 26 ka, from the Rockall Trough (NE Atlantic)
Core MD04-2822 from the Rockall Trough has apparent sedimentation rates of ⌠1 m/kyr during the last deglaciation (Termination I). Component magnetization directions indicate a magnetic excursion at 16.3 m depth in the core, corresponding to an age of 26.5 ka, implying an excursion duration of âŒ350 years. Across Termination I, the mean grain size of sortable silt implies reduced bottom-current velocity in the Younger Dryas and Heinrich Stadial (HS)â1A, and increased velocities during the BĂžlling-AllerĂžd warm period. Standard bulk magnetic parameters imply fining of magnetic grain size from the mid-Younger Dryas (âŒ12 ka) until ⌠8 ka. First-order reversal curves (FORCs) were analyzed using ridge extraction to differentiate single domain (SD) from background (detrital) components. Principal component analysis (FORC-PCA) was then used to discriminate three end members corresponding to SD, pseudo-single domain (PSD), and multidomain (MD) magnetite. The fining of bulk magnetic grain size from 12 to 8 ka is due to reduction in concentration of detrital (PSDâ+âMD) magnetite, superimposed on a relatively uniform concentration of SD magnetite produced by magnetotactic bacteria. The decrease in PSD+MD magnetite concentration from 12 to 8 ka is synchronized with increase in benthic ÎŽ13C, and with major (âŒ70 m) regional sea-level rise, and may therefore be related to detrital sources on the shelf that had reduced influence as sea level rose, and to bottom-water reorganization as Northern Source Water (NSW) replaced Southern Source Water (SSW)
UV Absorption Lines from High-Velocity Gas in the Vela Supernova Remnant: New insights from STIS Echelle Observations of HD72089
The star HD72089 is located behind the Vela supernova remnant and shows a
complex array of high and low velocity interstellar absorption features arising
from shocked clouds. A spectrum of this star was recorded over the wavelength
range 1196.4 to 1397.2 Angstroms at a resolving power lambda/Delta lambda =
110,000 and signal-to-noise ratio of 32 by STIS on the Hubble Space Telescope.
We have identified 7 narrow components of C I and have measured their relative
populations in excited fine-structure levels. Broader features at heliocentric
velocities ranging from -70 to +130 km/s are seen in C II, N I, O I, Si II, S
II and Ni II. In the high-velocity components, the unusually low abundances of
N I and O I, relative to S II and Si II, suggest that these elements may be
preferentially ionized to higher stages by radiation from hot gas immediately
behind the shock fronts.Comment: 11 pages, 2 figures, Latex. Submitted for the special HST ERO issue
of the Astrophysical Journal Letter
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