5,853 research outputs found
Use of Earth Resources Technological Satellite (ERTS) data in a natural resource inventory
There are no author-identified significant results in this report
Discovery of 6.035GHz Hydroxyl Maser Flares in IRAS18566+0408
We report the discovery of 6.035GHz hydroxyl (OH) maser flares toward the
massive star forming region IRAS18566+0408 (G37.55+0.20), which is the only
region known to show periodic formaldehyde (4.8 GHz H2CO) and methanol (6.7 GHz
CH3OH) maser flares. The observations were conducted between October 2008 and
January 2010 with the 305m Arecibo Telescope in Puerto Rico. We detected two
flare events, one in March 2009, and one in September to November 2009. The OH
maser flares are not simultaneous with the H2CO flares, but may be correlated
with CH3OH flares from a component at corresponding velocities. A possible
correlated variability of OH and CH3OH masers in IRAS18566+0408 is consistent
with a common excitation mechanism (IR pumping) as predicted by theory.Comment: Accepted for publication in the Astrophysical Journa
Intumescent Coatings as Fire Retardants
Fire-retardant paint, when activated by the heat of fire, reacts to form a thick, low-density, polymeric coating or char layer. Water vapor and sulphur dioxide are released during the intumescent reaction
Orthopaedic nurses’ engagement in clinical research; an exploration of ideas, facilitators and challenges
Background: Previous international studies have identified individual and organisational barriers to nurses’ research utilisation, but there is little data reporting on nurses’ engagement in research design and/or delivery, particularly within the orthopaedic speciality.
Aim: To explore orthopaedic nurses’ views regarding the research priorities for neuro-musculoskeletal care and the perceived barriers and facilitators associated with their engagement in the research process.
Methods: A single centre mixed methods study (n=75) collected data via a survey and 14 focus group discussions.
Findings: Our sample of clinical orthopaedic nurses showed little evidence of research engagement. Research priorities focused on 1. Understanding and improving patient and staff experiences 2. Improving processes, systems and workload models 3. Interventions to improve clinical outcomes. Key themes arising from the focus group discussion data were research activity, priorities and motivation, culture and leadership, and resources.
Conclusion: Our findings suggest that there is still significant work to do build sufficient research capacity and capability within the nursing workforce. Key to success will be developing effective leaders, who can create a positive and supportive research culture across an organisation to strengthen the research voice of nursing, which will drive improvements in future care
Masses of Nearby Supermassive Black Holes with Very-Long Baseline Interferometry
Dynamical mass measurements to date have allowed determinations of the mass M
and the distance D of a number of nearby supermassive black holes. In the case
of Sgr A*, these measurements are limited by a strong correlation between the
mass and distance scaling roughly as M ~ D^2. Future very-long baseline
interferometric (VLBI) observations will image a bright and narrow ring
surrounding the shadow of a supermassive black hole, if its accretion flow is
optically thin. In this paper, we explore the prospects of reducing the
correlation between mass and distance with the combination of dynamical
measurements and VLBI imaging of the ring of Sgr A*. We estimate the signal to
noise ratio of near-future VLBI arrays that consist of five to six stations,
and we simulate measurements of the mass and distance of Sgr A* using the
expected size of the ring image and existing stellar ephemerides. We
demonstrate that, in this best-case scenario, VLBI observations at 1 mm can
improve the error on the mass by a factor of about two compared to the results
from the monitoring of stellar orbits alone. We identify the additional sources
of uncertainty that such imaging observations have to take into account. In
addition, we calculate the angular diameters of the bright rings of other
nearby supermassive black holes and identify the optimal targets besides Sgr A*
that could be imaged by a ground-based VLBI array or future space-VLBI missions
allowing for refined mass measurements.Comment: 8 pages, 4 figures, 2 tables, refereed version, accepted for
publication in Ap
A New Estimate of the Cutoff Value in the Bak-Sneppen Model
We present evidence that the Bak-Sneppen model of evolution on vertices
requires iterates to reach equilibrium. This is substantially more than
previous authors suggested (on the order of ). Based on that estimate, we
present a novel algorithm inspired by previous rank-driven analyses of the
model allowing for direct simulation of the model with populations of up to for iterations. These extensive simulations suggest a
cutoff value of , a value slightly lower than
previously estimated yet still distinctly above . We also study how the
cutoff values at finite approximate the conjectured value at
. Assuming , we find that
, which is significantly lower than previous estimates
().Comment: 18 figures, 12 page
Relative Astrometry of Compact Flaring Structures in Sgr A* with Polarimetric VLBI
We demonstrate that polarimetric interferometry can be used to extract
precise spatial information about compact polarized flares of Sgr A*. We show
that, for a faint dynamical component, a single interferometric baseline
suffices to determine both its polarization and projected displacement from the
quiescent intensity centroid. A second baseline enables two-dimensional
reconstruction of the displacement, and additional baselines can self-calibrate
using the flare, enhancing synthesis imaging of the quiescent emission. We
apply this technique to simulated 1.3-mm wavelength observations of a "hot
spot" embedded in a radiatively inefficient accretion disk around Sgr A*. Our
results indicate that, even with current sensitivities, polarimetric
interferometry with the Event Horizon Telescope can achieve ~5 microarcsecond
relative astrometry of compact flaring structures near Sgr A* on timescales of
minutes.Comment: 9 Pages, 4 Figures, accepted for publication in Ap
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