321 research outputs found
Climate Change-Driven Cumulative Mountain Pine Beetle-Caused Whitebark Pine Mortality in the Greater Yellowstone Ecosystem
An aerial survey method called the Landscape Assessment System (LAS) was used to assess mountain pine beetle (Dendroctonus ponderosae)-caused mortality of whitebark pine (Pinus albicaulis) across the Greater Yellowstone Ecosystem (59,000 km2; GYE). This consisted of 11,942 km of flightlines, along which 4434 geo-tagged, oblique aerial photos were captured and processed. A mortality rating of none to severe (0â4.0 recent attack or 5.0â5.4 old attack) was assigned to each photo based on the amount of red (recent attack) and gray (old attack) trees visible. The method produced a photo inventory of 74 percent of the GYE whitebark pine distribution. For the remaining 26 percent of the distribution, mortality levels were estimated based on an interpolated mortality surface. Catchment-level results combining the photo-inventoried and interpolated mortality indicated that 44 percent of the GYE whitebark pine distribution showed severe old attack mortality (5.3â5.4 rating), 37 percent showed moderate old attack mortality (5.2â5.29 rating), 19 percent showed low old attack mortality (5.1â5.19 rating) and less than 1 percent showed trace levels of old attack mortality (5.0â5.09). No catchments were classified as recent attacks indicating that the outbreak of the early 2000âs has ended. However, mortality continues to occur as chronic sub-outbreak-level mortality. Ground verification using field plots indicates that higher LAS mortality values are moderately correlated with a higher percentage of mortality on the ground
Acute ST-Elevation Myocardial Infarction in Patients Hospitalized for Noncardiac Conditions
BackgroundMajor advances have been made in the treatment of STâelevation myocardial infarction (STEMI) in outpatients. In contrast, little is known about outcomes in STEMI that occur in patients hospitalized for a noncardiac condition.Methods and ResultsThis was a retrospective, singleâcenter study of inpatient STEMIs from January 1, 2007, to July 31, 2011. Fortyâeight cases were confirmed to be inpatient STEMIs of a total of 139 410 adult discharges. These patients were older and more often female and had higher rates of chronic kidney disease and prior cerebrovascular events compared with 227 patients with outpatient STEMIs treated during the same period. Onset of inpatient STEMI was heralded most frequently by a change in clinical status (60%) and less commonly by patient complaints (33%) or changes on telemetry. Coronary angiography and percutaneous coronary intervention were performed in 71% and 56% of patients, respectively. The median time to obtain ECG (41 [10, 600] versus 5 [2, 10] minutes; P<0.001), ECG to angiography time (91 [26, 209] versus 35 [25, 46] minutes; P<0.001) and ECG to first device activation (FDA) (129 [65, 25] versus 60 [47, 76] minutes; P<0.001) were longer for inpatient versus outpatient STEMI. Survival to discharge was lower for inpatient STEMI (60% versus 96%; P<0.001), and this difference persisted after adjusting for potential confounders.ConclusionsPatients who develop a STEMI while hospitalized for a noncardiac condition are older and more often female, have more comorbidities, have longer ECGâtoâFDA times, and are less likely to survive than patients with an outpatient STEMI
Simulating Heliospheric and Solar Particle Diffusion using the Parker Spiral Geometry
Cosmic Ray transport in curved background magnetic fields is investigated
using numerical Monte-Carlo simulation techniques. Special emphasis is laid on
the Solar system, where the curvature of the magnetic field can be described in
terms of the Parker spiral. Using such geometries, parallel and perpendicular
diffusion coefficients have to be re-defined using the arc length of the field
lines as the parallel displacement and the distance between field lines as the
perpendicular displacement. Furthermore, the turbulent magnetic field is
incorporated using a WKB approach for the field strength. Using a test-particle
simulation, the diffusion coefficients are then calculated by averaging over a
large number of particles starting at the same radial distance from the Sun and
over a large number of turbulence realizations, thus enabling one to infer the
effects due to the curvature of the magnetic fields and associated drift
motions.Comment: accepted for publication at Journal of Geophysical Research - Space
Physic
The effectiveness of computerized order entry at reducing preventable adverse drug events and medication errors in hospital settings: A systematic review and meta-analysis
Background: The Health Information Technology for Economic and Clinical Health (HITECH) Act subsidizes implementation by hospitals of electronic health records with computerized provider order entry (CPOE), which may reduce patient injuries caused by medication errors (preventable adverse drug events, pADEs). Effects on pADEs have not been rigorously quantified, and effects on medication errors have been variable. The objectives of this analysis were to assess the effectiveness of CPOE at reducing pADEs in hospital-related settings, and examine reasons for heterogeneous effects on medication errors. Methods: Articles were identified using MEDLINE, Cochrane Library, Econlit, web-based databases, and bibliographies of previous systematic reviews (September 2013). Eligible studies compared CPOE with paper-order entry in acute care hospitals, and examined diverse pADEs or medication errors. Studies on children or with limited event-detection methods were excluded. Two investigators extracted data on events and factors potentially associated with effectiveness. We used random effects models to pool data. Results: Sixteen studies addressing medication errors met pooling criteria; six also addressed pADEs. Thirteen studies used pre-post designs. Compared with paper-order entry, CPOE was associated with half as many pADEs (pooled risk ratio (RR) = 0.47, 95% CI 0.31 to 0.71) and medication errors (RR = 0.46, 95% CI 0.35 to 0.60). Regarding reasons for heterogeneous effects on medication errors, five intervention factors and two contextual factors were sufficiently reported to support subgroup analyses or meta-regression. Differences between commercial versus homegrown systems, presence and sophistication of clinical decision support, hospital-wide versus limited implementation, and US versus non-US studies were not significant, nor was timing of publication. Higher baseline rates of medication errors predicted greater reductions (P < 0.001). Other context and implementation variables were seldom reported. Conclusions: In hospital-related settings, implementing CPOE is associated with a greater than 50% decline in pADEs, although the studies used weak designs. Decreases in medication errors are similar and robust to variations in important aspects of intervention design and context. This suggests that CPOE implementation, as subsidized under the HITECH Act, may benefit public health. More detailed reporting of the context and process of implementation could shed light on factors associated with greater effectiveness
Dissipative Dynamics of Collisionless Nonlinear Alfven Wave Trains
The nonlinear dynamics of collisionless Alfven trains, including resonant
particle effects is studied using the kinetic nonlinear Schroedinger (KNLS)
equation model. Numerical solutions of the KNLS reveal the dynamics of Alfven
waves to be sensitive to the sense of polarization as well as the angle of
propagation with respect to the ambient magnetic field. The combined effects of
both wave nonlinearity and Landau damping result in the evolutionary formation
of stationaryOA S- and arc-polarized directional and rotational
discontinuities. These waveforms are freqently observed in the interplanetary
plasma.Comment: REVTeX, 6 pages (including 5 figures). This and other papers may be
found at http://sdphpd.ucsd.edu/~medvedev/papers.htm
Metallicity of solar-type stars with debris discs and planets
Around 16% of the solar-like stars in our neighbourhood show IR-excesses due
to debris discs and a fraction of them are known to host planets. We aim to
determine in a homogeneous way the metallicity of a sample of stars with known
debris discs and planets. Our analysis includes the calculation of the
fundamental stellar parameters by applying the iron ionisation equilibrium
conditions to several isolated Fe I and Fe II lines. The metallicity
distributions of the different stellar samples suggest that there is a
transition toward higher metallicities from stars with neither debris discs nor
planets to stars hosting giant planets. Stars with debris discs and stars with
neither debris nor planets follow a similar metallicity distribution, although
the distribution of the first ones might be shifted towards higher
metallicities. Stars with debris discs and planets have the same metallicity
behaviour as stars hosting planets, irrespective of whether the planets are
low-mass or gas giants. In the case of debris discs and giant planets, the
planets are usually cool, -semimajor axis larger than 0.1 AU. The data also
suggest that stars with debris discs and cool giant planets tend to have a low
dust luminosity, and are among the less luminous debris discs known. We also
find evidence of an anticorrelation between the luminosity of the dust and the
planet eccentricity. Our data show that the presence of planets, not the debris
disc, correlates with the stellar metallicity. The results confirm that
core-accretion models represent suitable scenarios for debris disc and planet
formation. Dynamical instabilities produced by eccentric giant planets could
explain the suggested dust luminosity trends observed for stars with debris
discs and planets.Comment: Accepted for publication by A&A, 17 pages, 10 figure
A Submillimetre Search for Cold Extended Debris Disks in the Beta Pictoris Moving Group
The Beta Pictoris Moving Group is a nearby stellar association of young
(12Myr) co-moving stars including the classical debris disk star beta Pictoris.
Due to their proximity and youth they are excellent targets when searching for
submillimetre emission from cold, extended, dust components produced by
collisions in Kuiper-Belt-like disks. They also allow an age independent study
of debris disk properties as a function of other stellar parameters. We
observed 7 infrared-excess stars in the Beta Pictoris Moving Group with the
LABOCA bolometer array, operating at a central wavelength of 870 micron at the
12-m submillimetre telescope APEX. The main emission at these wavelengths comes
from large, cold dust grains, which constitute the main part of the total dust
mass, and hence, for an optically thin case, make better estimates on the total
dust mass than earlier infrared observations. Fitting the spectral energy
distribution with combined optical and infrared photometry gives information on
the temperature and radial extent of the disk. From our sample, beta Pic,
HD181327, and HD172555 were detected with at least 3-sigma certainty, while all
others are below 2-sigma and considered non-detections. The image of beta Pic
shows an offset flux density peak located near the south-west extension of the
disk, similar to the one previously found by SCUBA at the JCMT. We present SED
fits for detected sources and give an upper limit on the dust mass for
undetected ones. We find a mean fractional dust luminosity f_dust=11x10^{-4} at
t=12Myr, which together with recent data at 100Myr suggests an f_dust propto
t^{-alpha} decline of the emitting dust, with alpha > 0.8.Comment: 11 pages, 3 figures, 3 tables; accepted for publication in Astronomy
& Astrophysic
Discrimination of conventional and organic white cabbage from a long-term field trial study using untargeted LC-MS-based metabolomics
The influence of organic and conventional farming practices on the content of single nutrients in plants is disputed in the scientific literature. Here, large-scale untargeted LC-MS-based metabolomics was used to compare the composition of white cabbage from organic and conventional agriculture, measuring 1,600 compounds. Cabbage was sampled in 2 years from one conventional and two organic farming systems in a rigidly controlled long-term field trial in Denmark. Using Orthogonal Projection to Latent Structures-Discriminant Analysis (OPLS-DA), we found that the production system leaves a significant (pâ=â0.013) imprint in the white cabbage metabolome that is retained between production years. We externally validated this finding by predicting the production system of samples from one year using a classification model built on samples from the other year, with a correct classification in 83% of cases. Thus, it was concluded that the investigated conventional and organic management practices have a systematic impact on the metabolome of white cabbage. This emphasizes the potential of untargeted metabolomics for authenticity testing of organic plant products
Solar Wind Turbulence and the Role of Ion Instabilities
International audienc
An all-sky survey of circular polarization at 200 MHz
We present results from the first all-sky radio survey in circular polarization. The survey uses the Murchison Widefield Array (MWA) to cover 30 900 sq deg, over declinations south of +30° and north of -86° centred at 200MHz (over a 169-231MHz band).We achieve a spatial resolution of ~3 arcmin and a typical sensitivity of 3.0mJy PSF-1over most of the survey region. We demonstrate a new leakage mitigation technique that reduces the leakage from total intensity into circular polarization by an order of magnitude. In a blind survey of the imaged region, we detect 14 pulsars in circular polarization above a 6s threshold. We also detect six transient sources associated with artificial satellites. A targeted survey of 2376 pulsars within the surveyed region yielded 33 detections above 4s. Looking specifically at pulsars previously detected at 200 MHz in total intensity, this represents a 35 per cent detection rate. We also conducted a targeted survey of 2400 known flare stars, this resulted in two tentative detections above 4s. A similar targeted search for 1506 known exoplanets in the field yielded no detections above 4s. The success of the survey suggests that similar surveys at longer wavelength bands and of deeper fields are warranted
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