4,785 research outputs found

    Multi-spectral window radiance observations of Cirrus from satellite and aircraft, November 2, 1986 Project FIRE

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    High resolution infrared radiance spectra achieved from the NASA ER2 airborne HIS experiment are used to analyze the spectral emissivity properties of cirrus clouds within the 8 to 12 micron atmospheric window region. Observations show that the cirrus emissivity generally decreases with increasing wavenumber (i.e., decreasing wavelength) within this band. A very abrupt decrease in emissivity (increase in brightness temperature) exists between 930/cm (10.8 microns) and 1000/cm (10.0 microns), the magnitude of the change being associated with the cirrus optical thickness as observed by lidar. The HIS observations are consistent with theoretical calculations of the spectral absorption coefficient for ice. The HIS observations imply that cirrus clouds can be detected unambiguously from the difference in brightness temperatures observed within the 8.2 and 11.0 micron window regions of the HIRS sounding radiometer flying on the operational NOAA satellites. This ability is demonstrated using simultaneous 25 km resolution HIRS observations and 1 km resolution AVHRR imagery achieved from the NOAA-9 satellite. Finally, the cirrus cloud location estimates combined with the 6.7 micron channel moisture imagery portray the boundaries of the ice/vapor phase of the upper troposphere moisture. This phase distinction is crucial for infrared radiative transfer considerations for weather and climate models, since upper tropospheric water vapor has little effect on the Earth's outgoing radiation whereas cirrus clouds have a very large attenuating effect

    The Kepler Light Curves of AGN: A Detailed Analysis

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    We present a comprehensive analysis of 21 light curves of Type 1 AGN from the Kepler spacecraft. First, we describe the necessity and development of a customized pipeline for treating Kepler data of stochastically variable sources like AGN. We then present the light curves, power spectral density functions (PSDs), and flux histograms. The light curves display an astonishing variety of behaviors, many of which would not be detected in ground-based studies, including switching between distinct flux levels. Six objects exhibit PSD flattening at characteristic timescales which roughly correlate with black hole mass. These timescales are consistent with orbital timescales or freefall accretion timescales. We check for correlations of variability and high-frequency PSD slope with accretion rate, black hole mass, redshift and luminosity. We find that bolometric luminosity is anticorrelated with both variability and steepness of the PSD slope. We do not find evidence of the linear rms-flux relationships or lognormal flux distributions found in X-ray AGN light curves, indicating that reprocessing is not a significant contributor to optical variability at the 0.1-10% level.Comment: 39 pages including 2 appendices. Accepted for Publication in the Astrophysical Journal, with higher resolution figure

    The clinical value of immunohistochemically demonstrable CEA in breast cancer: a possible method of selecting patients for adjuvant chemotherapy.

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    The production of carcinoembryonic antigen (CEA) by human breast cancer tissue has been studied in relation to the prognosis of patients with breast cancer. All of the patients were in a controlled trial of adjuvant chemotherapy for the treatment of operable breast cancer. CEA was studied in primary tumours and axillary node metastases from these patients using an immunoperoxidase (PAP) method. Sections of 290 primary carcinomas and 217 axillary metastases were examined for CEA. The CEA status of the primary tumours was of no value as a prognostic indicator nor in the selection of patients for chemotherapy. In contrast, patients could be divided into 3 groups on the basis of the CEA results in the axillary nodes. In one group, in which cases were strongly positive for CEA (24% of the total) the prognosis, as reflected by recurrence free survival, was relatively good and chemotherapy produced no further advantage. In another group in which cases were weakly positive for CEA (18% of the total) the prognosis was poor but chemotherapy produced significant improvement. In a third group, in which cases were negative for CEA (58% of the total) the prognosis was poor and was not improved by chemotherapy, at least in the short term. Thus, the CEA status of axillary metastases may be clinically useful

    KSwAGS: A Swift X-ray and UV Survey of the Kepler Field. I

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    We introduce the first phase of the Kepler-Swift Active Galaxies and Stars survey (KSwAGS), a simultaneous X-ray and UV survey of ~6 square degrees of the Kepler field using the Swift XRT and UVOT. We detect 93 unique X-ray sources with S/N>3 with the XRT, of which 60 have observed UV counterparts. We use the Kepler Input Catalog (KIC) to obtain the optical counterparts of these sources, and construct the X-ray to optical flux ratio as a first approximation of the classification of the source. The survey produces a mixture of stellar sources, extragalactic sources, and sources which we are not able to classify with certainty. We have obtained optical spectra for thirty of these targets, and are conducting an ongoing observing campaign to fully identify the sample. For sources classified as stellar or AGN with certainty, we construct SEDs using the 2MASS, UBV and GALEX data supplied for their optical counterparts by the KIC, and show that the SEDs differ qualitatively between the source types, and so can offer a method of classification in absence of a spectrum. Future papers in this series will analyze the timing properties of the stars and AGN in our sample separately. Our survey provides the first X-ray and UV data for a number of known variable stellar sources, as well as a large number of new X-ray detections in this well-studied portion of the sky. The KSwAGS survey is currently ongoing in the K2 ecliptic plane fields.Comment: Accepted for publication in the Astronomical Journal. 19 pages, 8 figures, 3 table

    Discovery of a cataclysmic variable with a sub-stellar companion

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    We find that the ROSAT source 1RXS J105010.3-140431 is a cataclysmic variable with orbital period of 88.6 minutes and a spectrum closely resembling WZ Sge. In particular, emission lines are flanked by Stark-broadened absorption wings probably originating in the photosphere of a compact object. The Balmer absorption lines can be modeled by the spectrum of a DA white dwarf with 13 000 <Teff<< T_{eff} < 24 000 K. The strong absorption lines allowed us to obtain direct radial velocities of the white dwarf using the cross-correlation technique. We find an extremely low white dwarf radial velocity half amplitude, KwdK_{wd} = 4 ±\pm 1 km s−1^{-1}. This is consistent with the upper limit obtained from the Hα\alpha emission line wing K < 20 km s−1^{-1}. The corresponding mass function is incompatible with a main sequence secondary, but is compatible with a post orbital period minimum cataclysmic variable with a brown dwarf-like secondary. The formal solution gives a secondary mass of 10-20 jovian masses. Doppler maps for the emission lines and the hypothesis of black-body emission indicate a steady state (T ∼r−3/4\sim r^{-3/4}) accretion disk mainly emitting in Hα\alpha and an optically thicker hotspot with a strong contribution to the higher order Balmer lines and \ion{He}{I} 5875. As in other long cycle length dwarf novae, evidence for inner disk removal is found from the analysis of the emission lines.Comment: 14 figures, 2 of them composed. Total 20 figures. Accepted for publication in Astronomy and Astrophysic

    Real-time Analysis and Selection Biases in the Supernova Legacy Survey

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    The Supernova Legacy Survey (SNLS) has produced a high-quality, homogeneous sample of Type Ia supernovae (SNe Ia) out to redshifts greater than z=1. In its first four years of full operation (to June 2007), the SNLS discovered more than 3000 transient candidates, 373 of which have been confirmed spectroscopically as SNe Ia. Use of these SNe Ia in precision cosmology critically depends on an analysis of the observational biases incurred in the SNLS survey due to the incomplete sampling of the underlying SN Ia population. This paper describes our real-time supernova detection and analysis procedures, and uses detailed Monte Carlo simulations to examine the effects of Malmquist bias and spectroscopic sampling. Such sampling effects are found to become apparent at z~0.6, with a significant shift in the average magnitude of the spectroscopically confirmed SN Ia sample towards brighter values for z>0.75. We describe our approach to correct for these selection biases in our three-year SNLS cosmological analysis (SNLS3), and present a breakdown of the systematic uncertainties involved.Comment: Accepted for publication in A

    Smith-Forbes, E., Howell, Dana M., Pitts, G., Willoughby, J., & Uhl, T. (Minimal Clinical Important Difference of the Quick Disabilities of the Arm, Shoulder, and Hand (Quickdash) for Post-Surgical Finger Phalanx Fractures

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    Purpose: STUDY DESIGN: Retrospective, multiple-group observational design. Objective: To determine the minimal clinically important difference (MCID) for the Quick Disabilities of the Arm, Should,er, and Hand (QuickDASH) outcome measure, for post-surgical palanx fracture diagnosis, using a triangulation of distribution-and-anchor-based approaches. Backgroudn: The MCID for the QuickDASH has been established using a pool of multiple conditions, and specifically for the shoulder, and other diagnoses in the elbow and wrist, but not for post-surgical finger fracture. Understanding specific threshold change values for post-surgical finger fracture can enhance the clinical decision-making process

    The Mission Continues: Engaging Post-9/11 Disabled Military Veterans in Civic Service

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    The Mission Continues: Engaging Post-9/11 Disabled Military Veterans in Civic Servic
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