1,177 research outputs found

    Our Parents, Ourselves: Health Care for an Aging Population; A Report of the Dartmouth Atlas Project

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    The new Dartmouth Atlas, funded by The John A. Hartford Foundation, is a report card that analyzes Medicare data to show us where the United States is making progress in patient-centered, evidence-based care for Medicare beneficiaries and where improvement is still needed. It also offers insight into regional variations in care.Filling in the gaps in our knowledge about the state of care across the country will help health care providers, health systems, and patients and families work together to improve care for all older adults.This Dartmouth Atlas report looks at a number of measures from Medicare data, including:The number of days older adults spend in contact with the health care system;Use of high-risk medications;Cancer screening rates (and how they compare with recommendations);30-day hospital readmission rates;Annual Wellness Visit (AWV) rates;Late hospice referral; andThe number of days spent in intensive care.The report also offers a historical look at key practices, comparing data from 2003-05 and 2012

    Microlensing of Globular Clusters as a Probe of Galactic Structure

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    The spatial distribution of compact dark matter in our Galaxy can be determined in a few years of monitoring Galactic globular clusters for microlensing. Globular clusters are the only dense fields of stars distributed throughout the three-dimensional halo and hence are uniquely suited to probe its structure. The microlensing optical depths towards different clusters have varying contributions from the thin disk, thick disk, bulge, and halo of the Galaxy. Although measuring individual optical depths to all the clusters is a daunting task, we show that interesting Galactic structure information can be extracted with as few as 4040--120120 events in total for the entire globular cluster system (observable with 2--5 years of monitoring). The globular cluster microlensing is particularly sensitive to the core radius of the halo mass distribution and to the scale length, surface mass density, and radial scale height variations of the thin disk.Comment: 14 pages, 1 figure. Submitted to ApJ Letters. Uses aastex macro

    Prompt optical observations of GRB050319 with the Swift UVOT

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    The UVOT telescope on the Swift observatory has detected optical afterglow emission from GRB 050319. The flux declines with a power law slope of alpha = -0.57 between the start of observations some 230 seconds after the burst onset (90s after the burst trigger) until it faded below the sensitivity threshold of the instrument after ~5 x 10^4s. There is no evidence for the rapidly declining component in the early light curve that is seen at the same time in the X-ray band. The afterglow is not detected in UVOT shortward of the B-band, suggesting a redshift of about 3.5. The optical V-band emission lies on the extension of the X-ray spectrum, with an optical to X-ray slope of beta = -0.8. The relatively flat decay rate of the burst suggests that the central engine continues to inject energy into the fireball for as long as a few x 10^4s after the burst.Comment: 16 pages, 4 figures, accepted by Ap

    The X-ray emission lines in GRB afterglows: the evidence for the two-component jet model

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    Recently, X-ray emission lines have been observed in X-ray afterglows of several γ\gamma-ray bursts. It is a major breakthrough for understanding the nature of the progenitors. It is proposed that the X-ray emission lines can be well explained by the Geometry-Dominated models, but in these models the illuminating angle is much larger than that of the collimated jet of the γ\gamma-ray bursts(GRBs). For GRB 011211, we obtain the illuminating angle is about θ45\theta\sim45^{\circ}, while the angle of GRB jet is only 3.63.6^{\circ}, so we propose that the outflow of the GRBs with emission lines should have two distinct components. The wide component illuminates the reprocessing material, and produces the emission lines, while the narrow one produces the γ\gamma-ray bursts. The observations show that the energy for producing the emission lines is higher than that of the GRBs. In this case, when the wide component dominates the afterglows, a bump will appear in the GRBs afterglows. For GRB 011211, the emergence time of the bump is less than 0.05 days after the GRB, it is obviously too early for the observation to catch it. With the presence of the X-ray emission lines there should also be a bright emission component between the UV and the soft X-rays. These features can be tested by the SwiftSwift satellite in the near future.Comment: 10 pags, 1 figure, ChJAA in pres

    Reionization: Characteristic Scales, Topology and Observability

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    Recently the numerical simulations of the process of reionization of the universe at z>6 have made a qualitative leap forward, reaching sufficient sizes and dynamic range to determine the characteristic scales of this process. This allowed making the first realistic predictions for a variety of observational signatures. We discuss recent results from large-scale radiative transfer and structure formation simulations on the observability of high-redshift Ly-alpha sources. We also briefly discuss the dependence of the characteristic scales and topology of the ionized and neutral patches on the reionization parameters.Comment: 4 pages, 5 figures (4 in color), to appear in Astronomy and Space Science special issue "Space Astronomy: The UV window to the Universe", proceedings of 1st NUVA Conference ``Space Astronomy: The UV window to the Universe'' in El Escorial (Spain

    Emission-Line Galaxies from the Hubble Space Telescope Probing Evolution and Reionization Spectroscopically (PEARS) Grism Survey. II: The Complete Sample

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    We present a full analysis of the Probing Evolution And Reionization Spectroscopically (PEARS) slitess grism spectroscopic data obtained with the Advanced Camera for Surveys on HST. PEARS covers fields within both the Great Observatories Origins Deep Survey (GOODS) North and South fields, making it ideal as a random survey of galaxies, as well as the availability of a wide variety of ancillary observations to support the spectroscopic results. Using the PEARS data we are able to identify star forming galaxies within the redshift volume 0< z<1.5. Star forming regions in the PEARS survey are pinpointed independently of the host galaxy. This method allows us to detect the presence of multiple emission line regions (ELRs) within a single galaxy. 1162 Ha, [OIII] and/or [OII] emission lines have been identified in the PEARS sample of ~906 galaxies down to a limiting flux of ~1e-18 erg/s/cm^2. The ELRs have also been compared to the properties of the host galaxy, including morphology, luminosity, and mass. From this analysis we find three key results: 1) The computed line luminosities show evidence of a flattening in the luminosity function with increasing redshift; 2) The star forming systems show evidence of disturbed morphologies, with star formation occurring predominantly within one effective (half-light) radius. However, the morphologies show no correlation with host stellar mass; and 3) The number density of star forming galaxies with M_* > 1e9} M_sun decreases by an order of magnitude at z<0.5 relative to the number at 0.5<z<0.9 in support of the argument for galaxy downsizing.Comment: Submitted. 48 pages. 19 figures. Accepted to Ap
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