4,038 research outputs found
Recommended from our members
Microstructures in Metasedimentary Rocks from the Neoproterozoic Bonahaven Formation, Scotland: Microconcretions, Impact Spherules, or Microfossils?
Microscopic spherules in relatively undeformed mudstones of the Neoproterozoic Bonahaven Formation, Islay, Scotland, are differentiated from their matrix by a sharp micron-scale, smoothly rounded boundary. These elongate spherules were earlier interpreted as hollow bodies filled penecontemporaneously by glauconite and subsequently metamorphosed to phengite, but their origin remains a matter of debate. Spherules observed in thin section are predominantly rounded (∼74%) but can exhibit a flat edge or protrusion at one end. In 11% of a sample population, two or more spherules are conjoined. X-ray diffraction indicates that spherule-bearing mudstones consist mainly of muscovite, with variable amounts of kaolin-group minerals and minor iron-chlorites. A range of physical origins for the spherules – including microconcretions or metamorphic microstructures; deposition from the sky as micrometeorites, microtektites/microkrystites, or accretionary volcanic ash particles; and detrital grains – is considered but rejected on distributional, morphological, and mineralogical evidence. Biological origins are considered most likely, especially protistan tests similar to the vase-shaped microfossils found in somewhat older Neoproterozoic rocks. If correct, this provides the first report of eukaryotic life in the Dalradian succession that passes critical tests for biogenicity and new evidence for testate microfossils in post-Sturtian but pre-Marinoan aged rocks.Earth and Planetary SciencesOrganismic and Evolutionary Biolog
Research IT maturity models for academic health centers: Early development and initial evaluation
This paper proposes the creation and application of maturity models to guide institutional strategic investment in research informatics and information technology (research IT) and to provide the ability to measure readiness for clinical and research infrastructure as well as sustainability of expertise. Conducting effective and efficient research in health science increasingly relies upon robust research IT systems and capabilities. Academic health centers are increasing investments in health IT systems to address operational pressures, including rapidly growing data, technological advances, and increasing security and regulatory challenges associated with data access requirements. Current approaches for planning and investment in research IT infrastructure vary across institutions and lack comparable guidance for evaluating investments, resulting in inconsistent approaches to research IT implementation across peer academic health centers as well as uncertainty in linking research IT investments to institutional goals. Maturity models address these issues through coupling the assessment of current organizational state with readiness for deployment of potential research IT investment, which can inform leadership strategy. Pilot work in maturity model development has ranged from using them as a catalyst for engaging medical school IT leaders in planning at a single institution to developing initial maturity indices that have been applied and refined across peer medical schools
The SDSS-2MASS-WISE Ten Dimensional Stellar Color Locus
We present the fiducial main sequence stellar locus traced by 10 photometric
colors observed by SDSS, 2MASS, and WISE. Median colors are determined using
1,052,793 stars with r-band extinction less than 0.125. We use this locus to
measure the dust extinction curve relative to the r-band, which is consistent
with previous measurements in the SDSS and 2MASS bands. The WISE band
extinction coefficients are larger than predicted by standard extinction
models. Using 13 lines of sight, we find variations in the extinction curve in
H, Ks, and WISE bandpasses. Relative extinction decreases towards Galactic
anti-center, in agreement with prior studies. Relative extinction increases
with Galactic latitude, in contrast to previous observations. This indicates a
universal mid-IR extinction law does not exist due to variations in dust grain
size and chemistry with Galactocentric position. A preliminary search for
outliers due to warm circumstellar dust is also presented, using stars with
high signal-to-noise in the W3-band. We find 199 such outliers, identified by
excess emission in Ks-W3. Inspection of SDSS images for these outliers reveals
a large number of contaminants due to nearby galaxies. Six sources appear to be
genuine dust candidates, yielding a fraction of systems with infrared excess of
0.120.05%.Comment: 11 pages, 10 figures, MNRAS Accepted. Tables 1 and 2 available
online: https://github.com/jradavenport/wise_locu
Experience treating electrical storm using an ultrasound guided stellate ganglion blockade
Introduction: Electrical storm is a life-threatening condition in an often medically complex patient population. Pharmacologic ultrasound-guided stellate ganglion blockade is a treatment option in combination with maximized systemic antiarrhythmic medications. There is an emerging body of case reports supporting stellate ganglion block efficacy and safety for this condition.
Methods: Retrospective study on ultrasound-guided stellate ganglion blocks for electrical storm investigating patient clinical characteristics, immediate and long-term outcomes, and procedure related complications.
Results: Four (75% men) critically ill patients maximized on standard antiarrhythmic therapy underwent six bedside ultrasound-guided stellate ganglion block procedures. All blocks were unilateral left-sided, two patients underwent repeat blocks for arrythmia reoccurrence. All patients experienced at least 12 hours free of ventricular arrhythmias with two thirds lasting beyond 24 hours. There were no observed complications.
Conclusions: Ultrasound-guided stellate ganglion block is an effective and safe temporizing treatment option for electrical storm. Our institution-specific multidisciplinary guidelines were helpful in providing guidance for the use of stellate ganglion blocks in electrical storm
- …