2,591 research outputs found

    Clues to Quasar Broad Line Region Geometry and Kinematics

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    We present evidence that the high-velocity CIV lambda 1549 emission line gas of radio-loud quasars may originate in a disk-like configuration, in close proximity to the accretion disk often assumed to emit the low-ionization lines. For a sample of 36 radio-loud z~2 quasars we find the 20--30% peak width to show significant inverse correlations with the fractional radio core-flux density, R, the radio axis inclination indicator. Highly inclined systems have broader line wings, consistent with a high-velocity field perpendicular to the radio axis. By contrast, the narrow line-core shows no such relation with R, so the lowest velocity CIV-emitting gas has an inclination independent velocity field. We propose that this low-velocity gas is located at higher disk-altitudes than the high-velocity gas. A planar origin of the high-velocity CIV-emission is consistent with the current results and with an accretion disk-wind emitting the broad lines. A spherical distribution of randomly orbiting broad-line clouds and a polar high-ionization outflow are ruled out.Comment: 5 Latex pages, 1 figure, accepted for publication in ApJ Letter

    Stability, reliability and cross-mode correlations of tests in a recommended 8-minute performance assessment battery

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    A need exists for an automated performance test system to study drugs, agents, treatments, and stresses of interest to the aviation, space, and environmental medical community. The purpose of this present study is to evaluate tests for inclusion in the NASA-sponsored Automated Performance Test System (APTS). Twenty-one subjects were tested over 10 replications with tests previously identified as good candidates for repeated-measure research. The tests were concurrently administered in paper-and-pencil and microcomputer modes. Performance scores for the two modes were compared. Data from trials 1 to 10 were examined for indications of test stability and reliability. Nine of the ten APT system tests achieved stability. Reliabilities were generally high. Cross-correlation of microbased tests with traditional paper-and-pencil versions revealed similarity of content within tests in the different modes, and implied at least three cognition and two motor factors. This protable, inexpensive, rugged, computerized battery of tests is recommended for use in repeated-measures studies of environmental and drug effects on performance. Identification of other tests compatible with microcomputer testing and potentially capable of tapping previously unidentified factors is recommended. Documentation of APTS sensitivity to environmental agents is available for more than a dozen facilities and is reported briefly. Continuation of such validation remains critical in establishing the efficacy of APTS tests

    Spectral Properties From Lyman-alpha to H-alpha For An Essentially Complete Sample of Quasars I: Data

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    We have obtained quasi-simultaneous ultraviolet-optical spectra for 22 out of 23 quasars in the complete PG-X-ray sample with redshift, z<0.4, and M_B<-23. The spectra cover rest-frame wavelengths from at least Lyman-alpha to H-alpha. Here we provide a detailed description of the data, including careful spectrophotometry and redshift determination. We also present direct measurements of the continua, strong emission lines and features, including Lyman-alpha, SiIV+OIV], CIV, CIII], SiIII], MgII, H-beta, [OIII], He5876+NaI5890,5896, H-alpha, and blended iron emission in the UV and optical. The widths, asymmetries and velocity shifts of profiles of strong emission lines show that CIV and Lyman-alpha are very different from H-beta and H-alpha. This suggests that the motion of the broad line region is related to the ionization structure, but the data appears not agree with the radially stratified ionization structure supported by reverberation mapping studies, and therefore suggest that outflows contribute additional velocity components to the broad emission line profiles.Comment: 42 pages, 10 figures, 13 tables. Accepted by AJ. Supplemental figures not included. Full version available at http://physics.uwyo.edu/~shang/pgxpaper/ShangPaper.pd

    Microcomputer-based tests for repeated-measures: Metric properties and predictive validities

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    A menu of psychomotor and mental acuity tests were refined. Field applications of such a battery are, for example, a study of the effects of toxic agents or exotic environments on performance readiness, or the determination of fitness for duty. The key requirement of these tasks is that they be suitable for repeated-measures applications, and so questions of stability and reliability are a continuing, central focus of this work. After the initial (practice) session, seven replications of 14 microcomputer-based performance tests (32 measures) were completed by 37 subjects. Each test in the battery had previously been shown to stabilize in less than five 90-second administrations and to possess retest reliabilities greater than r = 0.707 for three minutes of testing. However, all the tests had never been administered together as a battery and they had never been self-administered. In order to provide predictive validity for intelligence measurement, the Wechsler Adult Intelligence Scale-Revised and the Wonderlic Personnel Test were obtained on the same subjects

    A critical synthesis of the role of the pharmacist in oral healthcare and management of medication-related osteonecrosis of the jaw

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    Abstract: Objective: To consolidate extant published evidence in relation to the potential of integrating oral healthcare for patients at risk of developing medication-related osteonecrosis of the jaw (MRONJ). Methods: A critical synthesis and consolidation of five publications was undertaken. As a mechanism of situating the extant work within the context of primary healthcare provision, the Rainbow Model of Integrated Care was applied as a theoretical lens through which the conceptual findings could be collectively applied to practice. Results: The critical synthesis revealed a thematic emergence relating to both formative and normative integration. The most salient of these were the identification of limited shared clinical records, and disconnection of oral healthcare provision from patients’ general medical care. The three levels of the Rainbow Model of Integrated Care reflected a series of issues for address. Conclusion: In the context of collaborative, multi-disciplinary working for patients at risk of development of MRONJ, pharmacists are a professional group which this research reveals to be an underutilised resource. Reduction of oral health inequality at all levels of patient care is a key priority and this research highlights areas for address in relation to requirements for interprofessional education, optimal communication and policies reflective and facilitative of these

    Neutrino Spin Transitions and the Violation of the Equivalence Principle

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    The violation of the equivalence principle (VEP) causing neutrino oscillations is of current interest. We study here the possibility of not only flavor oscillation but spin flavor oscillation of ultra high energy ( \sim 1 PeV) neutrinos emanating from AGN due to VEP and due to the presence of a large magnetic field ( \sim 1 Tesla) in AGN. In particular we look at the resonance spin flavor conversion driven by the AGN potential. Interesting bounds on the transition magnetic moment of neutrinos may therefore be obtained.Comment: Latex, 12 pages, no figures. To appear in Journal of Physics G: Nuclear and Particle Physics. Two references adde

    An Empirical Ultraviolet Template for Iron Emission in Quasars as Derived from I Zw 1

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    We present an empirical template spectrum suitable for fitting/subtracting and studying the FeII and FeIII line emission in the restframe UV spectra of active galatic nuclei (AGNs), the first empirical UV iron template to cover the full 1250 - 3090 A range. Iron emission is often a severe contaminant in optical--UV spectra of AGNs. Its presence complicates and limits the accuracy of measurements of both strong and weak emission lines and the continuum emission, affecting studies of line and continuum interrelations, the ionization structure, and elemental abundances in AGNs. Despite the wealth of work on modeling the AGN FeII emission and the need to account for it in observed AGN spectra, there is no UV template electronically available to aid this process. The iron template we present is based on HST spectra of the Narrow Line Seyfert 1, IZw1. Its intrinsic narrow lines (~900 km/s) and rich iron spectrum make the template particularly suitable for use with most AGN spectra. The iron emission spectrum and the line identifications and measurements are presented and compared with the work of Laor et al. We illustrate the application of the derived FeII and FeIII templates by fitting and subtracting the iron emission from UV spectra of four high-z quasars and of the nearby quasar, 3C273. We briefly discuss the small discrepancies between this observed iron emission and the UV template, and compare the template with previously published ones. We discuss the advantages and limitations of the templates and of the template fitting method. We conclude that the templates work sufficiently well to be a valuable and important tool for eliminating and studying the iron emission in AGNs, at least until accurate theoretical iron emission models are developed. (Abridged)Comment: 73 pages including 7 figures, 6 tables. To appear in ApJS. Preprint is also available at http://www.astronomy.ohio-state.edu/~vester/IronEmission

    Stormy weather in 3C 196.1: nuclear outbursts and merger events shape the environment of the hybrid radio galaxy 3C 196.1

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    We present a multi-wavelength analysis based on archival radio, optical and X-ray data of the complex radio source 3C 196.1, whose host is the brightest cluster galaxy of a z=0.198z=0.198 cluster. HST data show Hα\alpha+[N II] emission aligned with the jet 8.4 GHz radio emission. An Hα\alpha+[N II] filament coincides with the brightest X-ray emission, the northern hotspot. Analysis of the X-ray and radio images reveals cavities located at galactic- and cluster- scales. The galactic-scale cavity is almost devoid of 8.4 GHz radio emission and the south-western Hα\alpha+[N II] emission is bounded (in projection) by this cavity. The outer cavity is co-spatial with the peak of 147 MHz radio emission, and hence we interpret this depression in X-ray surface brightness as being caused by a buoyantly rising bubble originating from an AGN outburst \sim280 Myrs ago. A \textit{Chandra} snapshot observation allowed us to constrain the physical parameters of the cluster, which has a cool core with a low central temperature \sim2.8 keV, low central entropy index \sim13 keV cm2^2 and a short cooling time of \sim500 Myr, which is <0.05<0.05 of the age of the Universe at this redshift. By fitting jumps in the X-ray density we found Mach numbers between 1.4 and 1.6, consistent with a shock origin. We also found compelling evidence of a past merger, indicated by a morphology reminiscent of gas sloshing in the X-ray residual image. Finally, we computed the pressures, enthalpies EcavE_{cav} and jet powers PjetP_{jet} associated with the cavities: Ecav7×1058E_{cav}\sim7\times10^{58} erg, Pjet1.9×1044P_{jet}\sim1.9\times10^{44} erg s1^{-1} for the inner cavity and Ecav3×1060E_{cav}\sim3\times10^{60} erg, Pjet3.4×1044P_{jet}\sim3.4\times10^{44} erg s1^{-1} for the outer cavity.Comment: 14 pages, 4 figures, ApJ accepte
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