400 research outputs found

    The Young Planetary System K2-25: Constraints on Companions and Starspots

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    The abundance of planets with orbital periods of a few to tens of days suggests that exoplanets experience complex dynamical histories. Planets in young stellar clusters or associations have well-constrained ages and therefore provide an opportunity to explore the dynamical evolution of exoplanets. K2-25b is a Neptune-sized planet in an eccentric, 3.48 day orbit around an M4.5 dwarf star in the Hyades cluster (650 Myr). In order to investigate its non-zero eccentricity and tight orbit, we analyze transit timing variations (TTVs) which could reveal clues to the migration processes that may have acted on the planet. We obtain 12 nonconsecutive transits using the MEarth observatories and long-term photometric monitoring, which we combine with 10 transits from the Spitzer Space Telescope and 20 transits from K2. Tables of MEarth photometry accompany this work. We fit each transit lightcurve independently. We first investigate whether inhomogeneities on the stellar surface (such as spots or plages) are differentially affecting our transit observations. The measured transit depth does not vary significantly between transits, though we see some deviations from the fiducial transit model. We then looked for TTVs as evidence of a nontransiting perturber in the system. We find no evidence for >1 M ? mass companions within a 2:1 period ratio, or for >5 M ? mass planets within a 7:2 period ratio

    Spousal influence on physical activity in middle-aged and older adults

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    Low physical activity levels are a public health concern. Few studies have assessed the concordance of physical activity change among spouses. We studied this concordance during a 6-year period (baseline: 1987-1989; follow-up: 1993-1995) in 3,261 spousal pairs from the US-based Atherosclerosis Risk in Communities (ARIC) Study. Linear regression was used to examine the association between change in individuals' sport/exercise and leisure physical activity indices (ranging from 1 (low) to 5 (high)) and change in his or her spouse's indices. The association between individual and spousal changes in meeting physical activity recommendations was assessed with logistic regression. Individual changes in the sport/exercise and leisure indices were positively associated with spousal changes. For every standard deviation increase in their wives' sport/exercise index, men's exercise index increased by 0.09 (95% confidence interval: 0.05, 0.12) standard deviation; for every standard deviation increase in their wives' leisure index, men's leisure index increased by 0.08 standard deviation. Results were similar for women. Individuals had higher odds of meeting physical activity recommendations if their spouse met recommendations at both visits or just follow-up. In conclusion, changes in an individual's physical activity are positively associated with changes in his or her spouse's physical activity. Physical activity promotion efforts should consider targeting couples

    Herbivorous turtle ants obtain essential nutrients from a conserved nitrogen-recycling gut microbiome.

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    Nitrogen acquisition is a major challenge for herbivorous animals, and the repeated origins of herbivory across the ants have raised expectations that nutritional symbionts have shaped their diversification. Direct evidence for N provisioning by internally housed symbionts is rare in animals; among the ants, it has been documented for just one lineage. In this study we dissect functional contributions by bacteria from a conserved, multi-partite gut symbiosis in herbivorous Cephalotes ants through in vivo experiments, metagenomics, and in vitro assays. Gut bacteria recycle urea, and likely uric acid, using recycled N to synthesize essential amino acids that are acquired by hosts in substantial quantities. Specialized core symbionts of 17 studied Cephalotes species encode the pathways directing these activities, and several recycle N in vitro. These findings point to a highly efficient N economy, and a nutritional mutualism preserved for millions of years through the derived behaviors and gut anatomy of Cephalotes ants

    Hospital to Home Transition for Patients With Stroke Under Bundled Payments

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    Bundled payments are a promising alternative payment model for reducing costs and improving the coordination of postacute stroke care, yet there is limited evidence supporting the effectiveness of bundled payments for stroke. This may be due to the lack of effective strategies to address the complex needs of stroke survivors. In this article, we describe COMprehensive Post-Acute Stroke Services (COMPASS), a comprehensive transitional care intervention focused on discharge from the acute care setting to home. COMPASS may serve as a potential care redesign strategy under bundled payments for stroke, such as the Centers for Medicare & Medicaid Innovation Bundled Payment for Care Improvement Initiative. The COMPASS care model is aligned with the incentive structures and essential components of bundled payments in terms of care coordination, patient assessment, patient and family involvement, and continuity of care. Ongoing evaluation will inform the design of incorporating COMPASS-like transitional care interventions into a stroke bundle

    The Cost of Implementing and Sustaining the COMprehensive Post-Acute Stroke Services Model

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    Background:The COMprehensive Post-Acute Stroke Services (COMPASS) model, a transitional care intervention for stroke patients discharged home, was tested against status quo postacute stroke care in a cluster-randomized trial in 40 hospitals in North Carolina. This study examined the hospital-level costs associated with implementing and sustaining COMPASS.Methods:Using an activity-based costing survey, we estimated hospital-level resource costs spent on COMPASS-related activities during approximately 1 year. We identified hospitals that were actively engaged in COMPASS during the year before the survey and collected resource cost estimates from 22 hospitals. We used median wage data from the Bureau of Labor Statistics and COMPASS enrollment data to estimate the hospital-level costs per COMPASS enrollee.Results:Between November 2017 and March 2019, 1582 patients received the COMPASS intervention across the 22 hospitals included in this analysis. Average annual hospital-level COMPASS costs were 2861perpatient(25thpercentile:2861 per patient (25th percentile: 735; 75th percentile: $3,475). Having 10% higher stroke patient volume was associated with 5.1% lower COMPASS costs per patient (P=0.016). About half (N=10) of hospitals reported postacute clinic visits as their highest-cost activity, while a third (N=7) reported case ascertainment (ie, identifying eligible patients) as their highest-cost activity.Conclusions:We found that the costs of implementing COMPASS varied across hospitals. On average, hospitals with higher stroke volume and higher enrollment reported lower costs per patient. Based on average costs of COMPASS and readmissions for stroke patients, COMPASS could lower net costs if the model is able to prevent about 6 readmissions per year

    Population overlap and habitat segregation in wintering Black-tailed Godwits Limosa limosa

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    Distinct breeding populations of migratory species may overlap both spatially and temporally, but differ in patterns of habitat use. This has important implications for population monitoring and conservation. To quantify the extent to which two distinct breeding populations of a migratory shorebird, the Black-tailed Godwit Limosa limosa, overlap spatially, temporally and in their use of different habitats during winter. We use mid-winter counts between 1990 and 2001 to identify the most important sites in Iberia for Black-tailed Godwits. Monthly surveys of estuarine mudflats and rice-fields at one major site, the Tejo estuary in Portugal in 2005-2007, together with detailed tracking of colour-ringed individuals, are used to explore patterns of habitat use and segregation of the Icelandic subspecies L. l. islandica and the nominate continental subspecies L. l. limosa. In the period 1990-2001, over 66 000 Black-tailed Godwits were counted on average in Iberia during mid-winter (January), of which 80% occurred at just four sites: Tejo and Sado lower basins in Portugal, and Coto Dontildeana and Ebro Delta in Spain. Icelandic Black-tailed Godwits are present throughout the winter and forage primarily in estuarine habitats. Continental Black-tailed Godwits are present from December to March and primarily use rice-fields. Iberia supports about 30% of the Icelandic population in winter and most of the continental population during spring passage. While the Icelandic population is currently increasing, the continental population is declining rapidly. Although the estuarine habitats used by Icelandic godwits are largely protected as Natura 2000 sites, the habitat segregation means that conservation actions for the decreasing numbers of continental godwits should focus on protection of rice-fields and re-establishment of freshwater wetlands

    Burden of Rare Sarcomere Gene Variants in the Framingham and Jackson Heart Study Cohorts

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    Rare sarcomere protein variants cause dominant hypertrophic and dilated cardiomyopathies. To evaluate whether allelic variants in eight sarcomere genes are associated with cardiac morphology and function in the community, we sequenced 3,600 individuals from the Framingham Heart Study (FHS) and Jackson Heart Study (JHS) cohorts. Out of the total, 11.2% of individuals had one or more rare nonsynonymous sarcomere variants. The prevalence of likely pathogenic sarcomere variants was 0.6%, twice the previous estimates; however, only four of the 22 individuals had clinical manifestations of hypertrophic cardiomyopathy. Rare sarcomere variants were associated with an increased risk for adverse cardiovascular events (hazard ratio: 2.3) in the FHS cohort, suggesting that cardiovascular risk assessment in the general population can benefit from rare variant analysis

    Author Correction: Herbivorous turtle ants obtain essential nutrients from a conserved nitrogen-recycling gut microbiome.

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    The originally published version of the Supplementary Information file associated with this Article contained an error in Supplementary Figure 3. Panel b was inadvertently replaced with a duplicate of panel a. The error has now been fixed and the corrected version of the Supplementary Information PDF is available to download from the HTML version of the Article

    Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory

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    Atmospheric parameters, such as pressure (P), temperature (T) and density, affect the development of extensive air showers initiated by energetic cosmic rays. We have studied the impact of atmospheric variations on extensive air showers by means of the surface detector of the Pierre Auger Observatory. The rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find that the observed behaviour is explained by a model including the effects associated with the variations of pressure and density. The former affects the longitudinal development of air showers while the latter influences the Moliere radius and hence the lateral distribution of the shower particles. The model is validated with full simulations of extensive air showers using atmospheric profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle Physic

    Low Q^2 Jet Production at HERA and Virtual Photon Structure

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    The transition between photoproduction and deep-inelastic scattering is investigated in jet production at the HERA ep collider, using data collected by the H1 experiment. Measurements of the differential inclusive jet cross-sections dsigep/dEt* and dsigmep/deta*, where Et* and eta* are the transverse energy and the pseudorapidity of the jets in the virtual photon-proton centre of mass frame, are presented for 0 < Q2 < 49 GeV2 and 0.3 < y < 0.6. The interpretation of the results in terms of the structure of the virtual photon is discussed. The data are best described by QCD calculations which include a partonic structure of the virtual photon that evolves with Q2.Comment: 20 pages, 5 Figure
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