130 research outputs found

    Distance Dependent Offsets between Parallaxes for Nearby Stars and Gaia DR1 Parallaxes

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    We use 612 single stars with previously published trigonometric parallaxes placing them within 25 pc to evaluate parallaxes released in Gaia's first data release (DR1). We find that the Gaia parallaxes are, on average, 0.24±0.020.24 \pm 0.02 mas smaller than the weighted mean trigonometric parallax values for these stars in the solar neighborhood. We also find that the offset changes with distance out to 100 pc, in the sense that the closer the star, the larger the offset. We find no systematic trends in the parallax offsets with stellar VV magnitude, VKV-K color, or proper motion. We do find that the offset is roughly twice as large for stars south of the ecliptic compared to those that are north.Comment: 14 pages, 2 figures, 3 tables, accepted for publication in ApJ Letter. The table 1 is available in its entirety in a machine-readable form in the online journa

    Distance-dependent Offsets between Parallaxes for Nearby Stars and Gaia DR1 Parallaxes

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    We use 612 single stars with previously published trigonometric parallaxes placing them within 25 pc to evaluate parallaxes released in Gaia's first data release (DR1). We find that the Gaia parallaxes are, on average, 0.24 ± 0.02 mas smaller than the weighted mean trigonometric parallax values for these stars in the solar neighborhood. We also find that the offset changes with distance out to 100 pc, in the sense that the closer the star, the larger the offset. We find no systematic trends in the parallax offsets with stellar V magnitude, V − K color, or proper motion. We do find that the offset is roughly twice as large for stars south of the ecliptic compared to those that are north

    Changing Pattern of Esophageal Cancer Incidence in New Mexico: A 30-Year Evaluation

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    The incidence of esophageal adenocarcinoma has increased over the last 30 years, especially in non-Hispanic whites (nHw). Recent work indicates an increase in Hispanic Americans (HA). It is important to understand the effect of ethnicity on cancer occurrence over a prolonged interval. We searched the New Mexico Tumor Registry for all cases of esophageal cancer from 1 January 1973 to 31 December 2002. Inclusion criteria were histologic diagnosis of adenocarcinoma or squamous cell carcinoma, ethnicity and gender. Incidence rates for both were compared among ethnic groups in 5-year intervals. Nine hundred eighty-eight patients met the criteria. Esophageal adenocarcinoma incidence rates/100,000 population increased significantly over 30 years; 1973–1977, 0.4 cases; 1978–1982, 0.4 cases; 1983–1987, 0.6 cases; 1988–1992, 1.2 cases, 1993–1997, 1.6 cases and 1998–2002, 2.2 cases; P < 0.001. Squamous cell carcinoma incidence rates remained unchanged during the interval. In nHw and HA, adenocarcinoma incidence rates increased significantly during the study period. In all minority groups, squamous cell carcinoma remained the major type. Esophageal adenocarcinoma incidence among nHw and HA increased from 1973 to 2002 in New Mexico. Squamous cell carcinoma remains predominant in minorities. Ethnicity may influence the histology or indicate an increased risk for certain types of esophageal cancer

    LSST: from Science Drivers to Reference Design and Anticipated Data Products

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    (Abridged) We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). A vast array of science will be enabled by a single wide-deep-fast sky survey, and LSST will have unique survey capability in the faint time domain. The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a wide-field ground-based system sited at Cerro Pach\'{o}n in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg2^2 field of view, and a 3.2 Gigapixel camera. The standard observing sequence will consist of pairs of 15-second exposures in a given field, with two such visits in each pointing in a given night. With these repeats, the LSST system is capable of imaging about 10,000 square degrees of sky in a single filter in three nights. The typical 5σ\sigma point-source depth in a single visit in rr will be 24.5\sim 24.5 (AB). The project is in the construction phase and will begin regular survey operations by 2022. The survey area will be contained within 30,000 deg2^2 with δ<+34.5\delta<+34.5^\circ, and will be imaged multiple times in six bands, ugrizyugrizy, covering the wavelength range 320--1050 nm. About 90\% of the observing time will be devoted to a deep-wide-fast survey mode which will uniformly observe a 18,000 deg2^2 region about 800 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to r27.5r\sim27.5. The remaining 10\% of the observing time will be allocated to projects such as a Very Deep and Fast time domain survey. The goal is to make LSST data products, including a relational database of about 32 trillion observations of 40 billion objects, available to the public and scientists around the world.Comment: 57 pages, 32 color figures, version with high-resolution figures available from https://www.lsst.org/overvie

    Prasugrel versus Clopidogrel for Acute Coronary Syndromes without Revascularization

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    peer reviewedBACKGROUND: The effect of intensified platelet inhibition for patients with unstable angina or myocardial infarction without ST-segment elevation who do not undergo revascularization has not been delineated. METHODS: In this double-blind, randomized trial, in a primary analysis involving 7243 patients under the age of 75 years receiving aspirin, we evaluated up to 30 months of treatment with prasugrel (10 mg daily) versus clopidogrel (75 mg daily). In a secondary analysis involving 2083 patients 75 years of age or older, we evaluated 5 mg of prasugrel versus 75 mg of clopidogrel. RESULTS: At a median follow-up of 17 months, the primary end point of death from cardiovascular causes, myocardial infarction, or stroke among patients under the age of 75 years occurred in 13.9% of the prasugrel group and 16.0% of the clopidogrel group (hazard ratio in the prasugre

    Clinical Utilities of Peripheral Blood Gene Expression Profiling in the Management of Cardiac Transplant Patients

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    Cardiac allografts induce host immune responses that lead to endomyocardial tissue injury and progressive graft dysfunction. Inflammatory cell infiltration and myocyte damage characterize acute cellular rejection (ACR) that presents episodically in either a subclinical or symptom-associated manner. Sampling of the endomyocardium by transvenous biopsy enables pathologic grading using light microscopic criteria to distinguish severity based on the focality or diffuseness of inflammation and associated myocyte injury. Monitoring for ACR utilizes endomyocardial biopsy in conjunction with history and physical examination and assessment of allograft function by echocardiography. However, procedural and interpretive issues limit the diagnostic certainty provided by endomyocardial biopsy. The dynamic profiling of genes expressed by peripheral blood mononuclear cells (PBMCs) enables quantitative assessments of intracellular mRNA whose levels fluctuate during systemic alloimmune responses. Gene expression profiling of PBMCs using a multi-gene ACR classifier enables the AlloMap® molecular expression test to distinguish moderate to severe ACR (p = 0.0018) in heart transplant patients. The AlloMap test provides molecular insights into a patient's risk for ACR by distilling the aggregate expression levels of its informative genes into a single score on a scale of 0 to 40. The selection of a score as a threshold value for clinical decision-making is based on its associated negative predictive value (NPV), which ranges from 98 to 99% for values in three post-transplant periods: >2 to ≤6 months, > 6to ≤ 12 months, and >12 months. Scores below the threshold value rule out ACR, while those above suggest increased ACR risk. Incorporating the AlloMap test into immunomonitoring protocols provides an opportunity for clinicians to enhance patient care and to define its role in immunodiagnostic strategies to optimize the clinical outcomes of heart transplant recipients. This summary highlights the concepts presented in an invited presentation at a conference focused on Immunodiagnostics and Immunomonitoring: From Research to Clinic, in San Diego, CA on November 7, 2006

    Flea Diversity as an Element for Persistence of Plague Bacteria in an East African Plague Focus

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    Plague is a flea-borne rodent-associated zoonotic disease that is caused by Yersinia pestis and characterized by long quiescent periods punctuated by rapidly spreading epidemics and epizootics. How plague bacteria persist during inter-epizootic periods is poorly understood, yet is important for predicting when and where epizootics are likely to occur and for designing interventions aimed at local elimination of the pathogen. Existing hypotheses of how Y. pestis is maintained within plague foci typically center on host abundance or diversity, but little attention has been paid to the importance of flea diversity in enzootic maintenance. Our study compares host and flea abundance and diversity along an elevation gradient that spans from low elevation sites outside of a plague focus in the West Nile region of Uganda (∼725–1160 m) to higher elevation sites within the focus (∼1380–1630 m). Based on a year of sampling, we showed that host abundance and diversity, as well as total flea abundance on hosts was similar between sites inside compared with outside the plague focus. By contrast, flea diversity was significantly higher inside the focus than outside. Our study highlights the importance of considering flea diversity in models of Y. pestis persistence

    Further Defining Spectral Type "Y" and Exploring the Low-mass End of the Field Brown Dwarf Mass Function

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    We present the discovery of another seven Y dwarfs from the Wide-field Infrared Survey Explorer (WISE). Using these objects, as well as the first six WISE Y dwarf discoveries from Cushing et al., we further explore the transition between spectral types T and Y. We find that the T/Y boundary roughly coincides with the spot where the J-H colors of brown dwarfs, as predicted by models, turn back to the red. Moreover, we use preliminary trigonometric parallax measurements to show that the T/Y boundary may also correspond to the point at which the absolute H (1.6 um) and W2 (4.6 um) magnitudes plummet. We use these discoveries and their preliminary distances to place them in the larger context of the Solar Neighborhood. We present a table that updates the entire stellar and substellar constituency within 8 parsecs of the Sun, and we show that the current census has hydrogen-burning stars outnumbering brown dwarfs by roughly a factor of six. This factor will decrease with time as more brown dwarfs are identified within this volume, but unless there is a vast reservoir of cold brown dwarfs invisible to WISE, the final space density of brown dwarfs is still expected to fall well below that of stars. We also use these new Y dwarf discoveries, along with newly discovered T dwarfs from WISE, to investigate the field substellar mass function. We find that the overall space density of late-T and early-Y dwarfs matches that from simulations describing the mass function as a power law with slope -0.5 < alpha < 0.0; however, a power-law may provide a poor fit to the observed object counts as a function of spectral type because there are tantalizing hints that the number of brown dwarfs continues to rise from late-T to early-Y. More detailed monitoring and characterization of these Y dwarfs, along with dedicated searches aimed at identifying more examples, are certainly required.Comment: 91 pages, 15 figures, accepted for publication in The Astrophysical Journa
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