635 research outputs found

    Predictive Modeling in Action: How 'Virtual Wards' Help High-Risk Patients Receive Hospital Care at Home

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    Describes a program to reduce hospitalizations by providing multidisciplinary case management and coordinated preventive care at home to chronic disease patients found to be at risk of emergency hospitalization by predictive modeling. Outlines challenges

    Phantom Energy and the Cosmic Horizon: Rh is still not a horizon!

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    There has been a recent spate of papers on the Cosmic Horizon, an apparently fundamental, although unrecognised, property of the universe. The misunderstanding of this horizon, it is claimed, demonstrates that our determination of the cosmological makeup of the universe is incorrect, although several papers have pointed out key flaws in these arguments. Here, we identify additional flaws in the most recent claims of the properties of the Cosmic Horizon in the presence of phantom energy, simply demonstrating that it does not act as a horizon, and that its limiting of our view of the universe is a trivial statement.Comment: 4 pages, 1 figure. Accepted for publication in MNRAS Letter

    Gravitational microlensing of planets: the influence of planetary phase and caustic orientation

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    Recent studies have demonstrated that detailed monitoring of gravitational microlensing events can reveal the presence of planets orbiting the microlensed source stars. With the potential of probing planets in the Galactic Bulge and Magellanic Clouds, such detections greatly increase the volume over which planets can be found. This paper expands on these original studies by considering the effect of planetary phase on the form of the resultant microlensing light curve. It is found that crescent-like sources can undergo substantially more magnification than a uniformly illuminated disk, the model typically employed in studying such planets. In fact, such a circularly symmetric model is found to suffer a minimal degree of magnification when compared to the crescent models. The degree of magnification is also a strong function of the planet's orientation with respect to the microlensing caustic. The form of the magnification variability is also strongly dependent on the planetary phase and from which direction it is swept by the caustic, providing further clues to the geometry of the planetary system. As the amount of light reflected from a planet also depends on its phase, the detection of extreme crescent-like planets requires the advent of 30-m class telescopes, while light curves of planets at more moderate phases can be determined with today's 10-m telescopes.Comment: 7 pages, 7 figures, to appear in the MNRA

    Strengthening Primary Care: Recent Reforms and Achievements in Australia, England, and the Netherlands

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    Outlines efforts to enhance primary care quality and access, including postgraduate training for family physicians, general practitioner accreditation, greater use of nurse practitioners, and after-hours care; their outcomes; and insights for U.S. reform

    Producing the Deuteron in Stars: Anthropic Limits on Fundamental Constants

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    Stellar nucleosynthesis proceeds via the deuteron (D), but only a small change in the fundamental constants of nature is required to unbind it. Here, we investigate the effect of altering the binding energy of the deuteron on proton burning in stars. We find that the most definitive boundary in parameter space that divides probably life-permitting universes from probably life-prohibiting ones is between a bound and unbound deuteron. Due to neutrino losses, a ball of gas will undergo rapid cooling or stabilization by electron degeneracy pressure before it can form a stable, nuclear reaction-sustaining star. We also consider a less-bound deuteron, which changes the energetics of the pppp and peppep reactions. The transition to endothermic pppp and peppep reactions, and the resulting beta-decay instability of the deuteron, do not seem to present catastrophic problems for life.Comment: 19 pages, 5 figures. Accepted to JCAP. Revised to match the published version; corrected to better take into account free neutron

    Microlensing of Broad Absorption Line Quasars

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    The physical nature of the material responsible for the high--velocity, broad-absorption line features seen in a small fraction of quasar spectra has been the subject of debate since their discovery. This has been especially compounded by the lack of observational probes of the absorbing region. In this paper we examine the role of ``microlenses'' in external galaxies on observed variability in the profiles of broad absorption lines in multiply-imaged quasars. Utilizing realistic models for both the broad absorption line region and the action of an ensemble of microlensing masses, we demonstrate that stars at cosmological distances can provide an important probe of the physical state and structure of material at the heart of these complex systems. Applying these results to the macrolensed BAL quasar system, H1413+117, the observed spectral variations are readily reproduced, but without the fine-tuning requirements of earlier studies which employ more simplistic models.Comment: 7 pages, 4 figures (included), Latex (mn.sty), Submitted to MNRA

    Was SN1997ff at z~1.7 magnified by gravitational lensing?

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    The quest for the cosmological parameters has come to fruition with the identification of a number of supernovae at a redshift of z∼1z\sim1. Analyses of the brightness of these standard candles reveal that the Universe is dominated by a large cosmological constant. The recent identification of the z∼1.7z\sim1.7 SN1997ff in the northern Hubble Deep Field has provided further evidence for this cosmology. Here we examine the case for gravitational lensing of SN1997ff due to the presence of galaxies lying along our line of sight. We find that, while the alignment of SN1997ff with foreground masses was not favorable for it to be multiply imaged and strongly magnified, two galaxies did lie close enough to result in significant magnification: μ∼1.4\mu\sim1.4 for the case where these elliptical galaxies have velocity dispersion 200km/s200 {\rm km/s}. Given the small difference between supernova brightnesses in different cosmologies, detailed modeling of the gravitational lensing properties of the intervening matter is therefore required before the true cosmological significance of SN1997ff can be deduced.Comment: 3 pages, 2 figures. Accepted for publication in MNRAS. Missing reference adde
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