13,428 research outputs found

    Observations of QSO J2233-606 in the Southern Hubble Deep Field

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    The Hubble Deep Field South (HDF-S) HST observations are expected to begin in October 1998. We present a composite spectrum of the QSO in the HDF-S field covering UV/optical/near IR wavelengths, obtained by combining data from the ANU 2.3m Telescope with STIS on the HST. This intermediate resolution spectrum covers the range 1600-10000A and allows us to derive some basic information on the intervening absorption systems which will be important in planning future higher resolution studies of this QSO.Comment: 9 pages and 2 figures, submitted to ApJ

    Experimental determination of stator endwall heat transfer

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    Local Stanton numbers were experimentally determined for the endwall surface of a turbine vane passage. A six vane linear cascade having vanes with an axial chord of 13.81 cm was used. Results were obtained for Reynolds numbers based on inlet velocity and axial chord between 73,000 and 495,000. The test section was connected to a low pressure exhaust system. Ambient air was drawn into the test section, inlet velocity was controlled up to a maximum of 59.4 m/sec. The effect of the inlet boundary layer thickness on the endwall heat transfer was determined for a range of test section flow rates. The liquid crystal measurement technique was used to measure heat transfer. Endwall heat transfer was determined by applying electrical power to a foil heater attached to the cascade endwall. The temperature at which the liquid crystal exhibited a specific color was known from a calibration test. Lines showing this specific color were isotherms, and because of uniform heat generation they were also lines of nearly constant heat transfer. Endwall static pressures were measured, along with surveys of total pressure and flow angles at the inlet and exit of the cascade

    Do Quasars Lens Quasars?

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    If the unexpectedly high frequency of quasar pairs with very different component redshifts is due to the lensing of a population of background quasars by the foreground quasar, typical lens masses must be \sim10^{12}M_{\sun} and the sum of all such quasar lenses would have to contain 0.005\sim0.005 times the closure density of the Universe. It then seems plausible that a very high fraction of all \sim10^{12} M_{\sun} gravitational lenses with redshifts z1z\sim1 contain quasars. Here I propose that these systems have evolved to form the present population of massive galaxies with MB22_{\rm B}\leq-22 and M >5\times10^{11} M_{\sun}.Comment: 6 pages, aas style, ams symbols, ApJL (accepted

    The Evolution of Radio Galaxies at Intermediate Redshift

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    We describe a new estimate of the radio galaxy 1.4 GHz luminosity function and its evolution at intermediate redshifts (z~0.4). Photometric redshifts and color selection have been used to select Bj<23.5 early-type galaxies from the Panoramic Deep Fields, a multicolor survey of two 25 sq deg fields. Approximately 230 radio galaxies have then been selected by matching early-type galaxies with NVSS radio sources brighter than 5 mJy. Estimates of the 1.4 GHz luminosity function of radio galaxies measure significant evolution over the observed redshift range. For an Omega_M=1 cosmology the evolution of the radio power is consistent with luminosity evolution where P(z)=P(0)(1+z)^{k_L} and 3<k_L<5. The observed evolution is similar to that observed for UVX and X-ray selected AGN and is consistent with the same physical process being responsible for the optical and radio luminosity evolution of AGN.Comment: 26 pages, 9 Figures, Accepted for Publication in A

    The Cambridge-Cambridge ROSAT Serendipity Survey - I. X-ray-luminous galaxies

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    We report on the first results obtained from a new optical identification programme of 123 faint X-ray sources with SS(0.5--2keV)>2×1014\,{\rm keV)}>2\times 10^{-14}\,erg\,s1^{-1}\,cm2^{-2}\, serendipitously detected in {\it ROSAT} PSPC pointed observations. We have spectroscopically identified the optical counterparts to more than 100 sources in this survey. Although the majority of the sample (68 objects) are QSOs, we have also identified 12 narrow emission line galaxies which have extreme X-ray luminosities (1042<LX<1043.510^{42} < L_{\rm X} < 10^{43.5}\,erg\,s1^{-1}). Subsequent spectroscopy reveals them to be a mixture of starburst galaxies and Seyfert 2 galaxies in approximately equal numbers. Combined with potentially similar objects identified in the {\it Einstein} Extended Medium Sensitivity Survey, these X-ray-luminous galaxies exhibit a rate of cosmological evolution, LX(1+z)2.5±1.0L_{\rm X} \propto (1+z)^{2.5\pm1.0}, consistent with that derived for X-ray QSOs. This evolution, coupled with the steep slope determined for the faint end of the X-ray luminosity function (Φ(LX)LX1.9\Phi(L_{\rm X}) \propto L_{\rm X}^{-1.9}), implies that such objects could comprise 15--35 per cent of the soft (1--2\,keV)Comment: Accepted for publication in MNRAS. 7 pages including 5 figures; uuencoded compressed postscript; RGO-21

    Incorporating patient preferences in the management of multiple long-term conditions: is this a role for clinical practice guidelines?

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    Background: Clinical practice guidelines provide an evidence-based approach to managing single chronic conditions, but their applicability to multiple conditions has been actively debated. Incorporating patient-preference recommendations and involving consumers in guideline development may enhance their applicability, but further understanding is needed. Objectives: To assess guidelines that include recommendations for comorbid conditions to determine the extent to which they incorporate patient-preference recommendations; use consumer-engagement processes during development, and, if so, whether these processes produce more patient-preference recommendations; and meet standard quality criteria, particularly in relation to stakeholder involvement. Design: A review of Australian guidelines published from 2006 to 2014 that incorporated recommendations for managing comorbid conditions in primary care. Document analysis of guidelines examined the presence of patient-preference recommendations and the consumer-engagement processes used. The Appraisal of Guidelines for Research and Evaluation instrument was used to assess guideline quality. Results: Thirteen guidelines were reviewed. Twelve included at least one core patient-preference recommendation. Ten used consumer-engagement processes, including participation in development groups (seven guidelines) and reviewing drafts (ten guidelines). More extensive consumer engagement was generally linked to greater incorporation of patient-preference recommendations. Overall quality of guidelines was mixed, particularly in relation to stakeholder involvement. Conclusions: Guidelines do incorporate some patient-preference recommendations, but more explicit acknowledgement is required. Consumer-engagement processes used during guideline development have the potential to assist in identifying patient preferences, but further research is needed. Clarification of the consumer role and investment in consumer training may strengthen these processes.Journal of Comorbidity 2015;5(1):122–13

    2dF QSO Redshift Survey

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    With approximately 6000 QSO redshifts,the 2dF QSO redshift survey is already the biggest complete QSO survey. The aim for the survey is to have 25000 QSO redshifts, providing an order of magnitude increase in QSO clustering statistics. We first describe the observational parameters of the 2dF QSO survey. We then describe several highlights of the survey so far, including new estimates of the QSO luminosity function and its evolution. We also review the current status of QSO clustering analyses from the 2dF data. Finally, we discuss how the complete QSO survey will be able to constrain the value of Omega_o by measuring the evolution of QSO clustering, place limits on the cosmological constant via a direct geometrical test and determine the form of the fluctuation power-spectrum out to the approximately 1000 Mpc scales only previously probed by COBE.Comment: 6 pages; to be published in Clustering at High Redshift, Marseille, June 1999, eds. A. Mazure, O. LeFevre, V. Lebru
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