1,214 research outputs found
The use of electronic alerts in primary care computer systems to identify the over-prescription of short-acting beta(2)-agonists in people with asthma: a protocol for a systematic review
The authors wish to thank the Asthma UK Centre for Applied Research for funding this work. AB is an National Institute for Health Research (NIHR) Senior Investigator and additionally was supported by the NIHR Respiratory Disease Biomedical Research Unit at the Royal Brompton and Harefield NHS Foundation Trust and Imperial College London. MT was supported by the NIHR Collaboration for Leadership in Applied Health Research and Care (CLAHRC) Wessex, NIHR School of Primary Care Research and NIHR Southampton Biomedical Research Centre. CG was supported by the NIHR CLAHRC North Thames at Bart’s Health NHS Trust
Reduced tillage in corn production
Caption title."Corn Belt Branch, Soil and Water Conservation Research Division, Agricultural Research Service, U.S. Department of Agriculture, Columbia, Missouri and the Agricultural Engineering Department of the Missouri Agricultural Experiment Station Cooperating"--Page [2]
On the Spatial Distribution of Stellar Populations in the Large Magellanic Cloud
We measure the angular correlation function of stars in a region of the Large
Magellanic Cloud (LMC) that spans 2 degrees by 1.5 degrees. We find that the
correlation functions of stellar populations are represented well by
exponential functions of the angular separation for separations between 2 and
40 arcmin (corresponding to ~ 30 pc and 550 pc for an LMC distance of 50 kpc).
The inner boundary is set by the presence of distinct, highly correlated
structures, which are the more familiar stellar clusters, and the outer
boundary is set by the observed region's size and the presence of two principal
centers of star formation within the region. We also find that the
normalization and scale length of the correlation function changes
systematically with the mean age of the stellar population. The existence of
positive correlation at large separations (~300 pc), even in the youngest
population, argues for large-scale hierarchical structure in current star
formation. The evolution of the angular correlation toward lower normalizations
and longer scale lengths with stellar age argues for the dispersion of stars
with time. We show that a simple, stochastic, self-propagating star formation
model is qualitatively consistent with this behavior of the correlation
function.Comment: 30 pages, 13 Figures. Scheduled for publication in AJ in June 199
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An analysis of plutonium immobilization versus the "spent fuel" standard
Safe Pu management is an important and urgent task with profound environmental, national, and international security implications. Presidential Policy Directive 13 and analyses by scientific, technical, and international policy organizations brought about a focused effort within the Department of Energy (DOE) to identify and implement long-term disposition paths for surplus Pu. The principal goal is to render surplus Pu as inaccessible and unattractive for reuse in nuclear weapons as Pu in spent reactor fuel. In the Programmatic Environmental Impact Statement and Record of Decision for the Storage and Disposition of Weapons- Usable Fissile Materials (1997), DOE announced pursuit of two disposition technologies: (1) irradiation of Pu as MOX fuel in existing reactors and (2) immobilization of Pu into solid forms containing fission products as a radiation barrier. DOE chose an immobilization approach that includes �use of the can-in-canister option.. . for a portion of the surplus, non-pit Pu material.� In the can-in-canister approach, cans of glass or ceramic forms containing Pu are encapsulated within canisters of HLW glass. In support of the selection process, a technical evaluation of retrievability and recoverability of Pu from glass and ceramic forms by a host nation and by rogue nations or subnational groups was completed. The evaluation involved determining processes and flowsheets for Pu recovery, comparing these processes against criteria and metrics established by the Fissile Materials Disposition Program and then comparing the recovery processes against each other and against SNF processes
Drift induced perpendicular transport of solar energetic particles
Drifts are known to play a role in galactic cosmic ray transport within the heliosphere and are a standard component of cosmic ray propagation models. However, the current paradigm of solar energetic particle (SEP) propagation holds the effects of drifts to be negligible, and they are not accounted for in most current SEP modeling efforts. We present full-orbit test particle simulations of SEP propagation in a Parker spiral interplanetary magnetic field (IMF), which demonstrate that high-energy particle drifts cause significant asymmetric propagation perpendicular to the IMF. Thus in many cases the assumption of field-aligned propagation of SEPs may not be valid. We show that SEP drifts have dependencies on energy, heliographic latitude, and charge-to-mass ratio that are capable of transporting energetic particles perpendicular to the field over significant distances within interplanetary space, e.g., protons of initial energy 100 MeV propagate distances across the field on the order of 1 AU, over timescales typical of a gradual SEP event. Our results demonstrate the need for current models of SEP events to include the effects of particle drift. We show that the drift is considerably stronger for heavy ion SEPs due to their larger mass-to-charge ratio. This paradigm shift has important consequences for the modeling of SEP events and is crucial to the understanding and interpretation of in situ observations. © 2013. The American Astronomical Society. All rights reserved.
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