10,225 research outputs found

    A Family History of Lethal Prostate Cancer and Risk of Aggressive Prostate Cancer in Patients Undergoing Radical Prostatectomy.

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    We investigated whether a family history of lethal prostate cancer (PCa) was associated with high-risk disease or biochemical recurrence in patients undergoing radical prostatectomy. A cohort of radical prostatectomy patients was stratified into men with no family history of PCa (NFH); a first-degree relative with PCa (FH); and those with a first-degree relative who had died of PCa (FHD). Demographic, operative and pathologic outcomes were analyzed. Freedom from biochemical recurrence was examined using Kaplan-Meier log rank. A multivariate Cox logistic regression analysis was also performed. We analyzed 471 men who underwent radical prostatectomy at our institution with known family history. The three groups had: 355 patients (75%) in NFH; 97 patients (21%) in FH; and 19 patients (4%) in FHD. The prevalence of a Gleason score ≥8, higher pathologic T stage, and biochemical recurrence (BCR) rates did not significantly differ between groups. On Kaplan-Meier analysis there were no differences in short-term BCR rates (p = 0.212). In this cohort of patients undergoing radical prostatectomy, those with first-degree relatives who died of PCa did not have an increased likelihood of high-risk or aggressive PCa or shorter-term risk of BCR than those who did not

    Development of Replacement Heifers using Combinations of Three Forage Types and Feed Supplements (with or without Broiler Litter)

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    The proper management of replacement heifers is an essential component of successful cow/calf operations. The level of management and nutrition applied to replacement heifers as calves and yearlings can impact their subsequent reproductive performance and productivity

    VETA-I x ray test analysis

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    This interim report presents some definitive results from our analysis of the VETA-I x-ray testing data. It also provides a description of the hardware and software used in the conduct of the VETA-I x-ray test program performed at the MSFC x-ray Calibration Facility (XRCF). These test results also serve to supply data and information to include in the TRW final report required by DPD 692, DR XC04. To provide an authoritative compendium of results, we have taken nine papers as published in the SPIE Symposium, 'Grazing Incidence X-ray/EUV Optics for Astronomy and Projection Lithography' and have reproduced them as the content of this report

    The X-ray R Aquarii: A Two-sided Jet and Central Source

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    We report Chandra ACIS-S3 x-ray imaging and spectroscopy of the R Aquarii binary system that show a spatially resolved two-sided jet and an unresolved central source. This is the first published report of such an x-ray jet seen in an evolved stellar system comprised of ~2-3 solar masses. At E < 1 keV, the x-ray jet extends both to the northeast and southwest relative to the central binary system. At 1 < E < 7.1 keV, R Aqr is a point-like source centered on the star system. While both 3.5-cm radio continuum emission and x-ray emission appear coincident in projection and have maximum intensities at ~7.5" northeast of the central binary system, the next strongest x-ray component is located \~30" southwest of the central binary system and has no radio continuum counterpart. The x-ray jets are likely shock heated in the recent past, and are not in thermal equilibrium. The strongest southwest x-ray jet component may have been shocked recently since there is no relic radio emission as expected from an older shock. At the position of the central binary, we detect x-ray emission below 1.6 keV consistent with blackbody emission at T ~2 x 10^6 K. At the central star there is also a prominent 6.4 keV feature, a possible fluorescence or collisionally excited Fe K-alpha line from an accretion disk or from the wind of the giant star. For this excitation to occur, there must be an unseen hard source of x-rays or particles in the immediate vicinity of the hot star. Such a source would be hidden from view by the surrounding edge-on accretion disk.Comment: PS, 20 pages, including 3 figures PNG, JPG - accepted for publication in ApJ Letters. Subject headings: stars: individual (R Aquarii) -- binaries: symbiotic -- circumstellar matter -- stars: white dwarfs -- stars: winds, outflows -- radio continuum: stars -- x-rays: genera

    VETA-1 x ray detection system

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    The alignment and X-ray imaging performance of the Advanced X-ray Astrophysics Facility (AXAF) Verification Engineering Test Article-I (VETA-I) was measured by the VETA-I X-Ray Detection System (VXDS). The VXDS was based on the X-ray detection system utilized in the AXAF Technology Mirror Assembly (TMA) program, upgraded to meet the more stringent requirements of the VETA-I test program. The VXDS includes two types of X-ray detectors: (1) a High Resolution Imager (HRI) which provides X-ray imaging capabilities, and (2) sealed and flow proportional counters which, in conjunction with apertures of various types and precision translation stages, provide the most accurate measurement of VETA-I performance. Herein we give an overview of the VXDS hardware including X-ray detectors, translation stages, apertures, proportional counters and flow counter gas supply system and associated electronics. We also describe the installation of the VXDS into the Marshall Space Flight Center (MSFC) X-Ray Calibration Facility (XRCF). We discuss in detail the design and performance of those elements of the VXDS which have not been discussed elsewhere; translation systems, flow counter gas supply system, apertures and thermal monitoring system

    Outer jet X-ray and radio emission in R Aquarii: 1999.8 to 2004.0

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    Chandra and VLA observations of the symbiotic star R Aqr in 2004 reveal significant changes over the three to four year interval between these observations and previous observations taken with the VLA in 1999 and with Chandra in 2000. This paper reports on the evolution of the outer thermal X-ray lobe-jets and radio jets. The emission from the outer X-ray lobe-jets lies farther away from the central binary than the outer radio jets, and comes from material interpreted as being shock heated to ~10^6 K, a likely result of collision between high speed material ejected from the central binary and regions of enhanced gas density. Between 2000 and 2004, the Northeast (NE) outer X-ray lobe-jet moved out away from the central binary, with an apparent projected motion of ~580 km s^-1. The Southwest (SW) outer X-ray lobe-jet almost disappeared between 2000 and 2004, presumably due to adiabatic expansion and cooling. The NE radio bright spot also moved away from the central binary between 2000 and 2004, but with a smaller apparent velocity than of the NE X-ray bright spot. The SW outer lobe-jet was not detected in the radio in either 1999 or 2004. The density and mass of the X-ray emitting material is estimated. Cooling times, shock speeds, pressure and confinement are discussed.Comment: 23 pages, 8 figure

    Hydrodynamical simulations of the jet in the symbiotic star MWC 560 III. Application to X-ray jets in symbiotic stars

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    In papers I and II in this series, we presented hydrodynamical simulations of jet models with parameters representative of the symbiotic system MWC 560. These were simulations of a pulsed, initially underdense jet in a high density ambient medium. Since the pulsed emission of the jet creates internal shocks and since the jet velocity is very high, the jet bow shock and the internal shocks are heated to high temperatures and should therefore emit X-ray radiation. In this paper, we investigate in detail the X-ray properties of the jets in our models. We have focused our study on the total X-ray luminosity and its temporal variability, the resulting spectra and the spatial distribution of the emission. Temperature and density maps from our hydrodynamical simulations with radiative cooling presented in the second paper are used together with emissivities calculated with the atomic database ATOMDB. The jets in our models show extended and variable X-ray emission which can be characterized as a sum of hot and warm components with temperatures that are consistent with observations of CH Cyg and R Aqr. The X-ray spectra of our model jets show emission line features which correspond to observed features in the spectra of CH Cyg. The innermost parts of our pulsed jets show iron line emission in the 6.4 - 6.7 keV range which may explain such emission from the central source in R Aqr. We conclude that MWC 560 should be detectable with Chandra or XMM-Newton, and such X-ray observations will provide crucial for understanding jets in symbiotic stars.Comment: 10 pages, 12 figures, accepted for publication in ApJ, uses emulateap

    Swift Observations of Hard X-ray Emitting White Dwarfs in Symbiotic Stars

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    The X-ray emission from most accreting white dwarfs (WDs) in symbiotic binary stars is quite soft. Several symbiotic WDs, however, produce strong X-ray emission at energies greater than ~20 keV. The Swift BAT instrument has detected hard X-ray emission from 4 such accreting WDs in symbiotic stars: RT Cru, T CrB, CD -57 3057, and CH Cyg. In one case (RT Cru), Swift detected X-rays out to greater than 50 keV at a > 5 sigma confidence level. Combining data from the XRT and BAT detectors, we find that the 0.3-150 keV spectra of RT Cru, T CrB, and CD -57 3057 are well described by emission from a single-temperature, optically thin thermal plasma, plus an unresolved 6.4-6.9 keV Fe line complex. The X-ray spectrum of CH Cyg contains an additional bright soft component. For all 4 systems, the spectra suffer high levels of absorption from material that both fully and partially covers the source of hard X-rays. The XRT data did not show any of the rapid, periodic variations that one would expect if the X-ray emission were due to accretion onto a rotating, highly magnetized WD. The X-rays were thus more likely from the accretion-disk boundary layer around a massive, non-magnetic WD in each binary. The X-ray emission from RT Cru varied on timescales of a few days. This variability is consistent with being due to changes in the absorber that partially covers the source, suggesting localized absorption from a clumpy medium moving into the line of sight. The X-ray emission from CD -57 3057 and T CrB also varied during the 9 months of Swift observations, in a manner that was also consistent with variable absorption.Comment: Accepted for publication in ApJ. 9 pages, 6 figure
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