4,977 research outputs found

    The Ultra-Fast Outflow of WKK 4438: Suzaku and NuSTAR X-ray Spectral Analysis

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    Previous X-ray spectral analysis has revealed an increasing number of AGNs with high accretion rates where an outflow with a mildly relativistic velocity originates from the inner accretion disk. Here we report the detection of a new ultra-fast outflow (UFO) with a velocity of vout=0.319βˆ’0.008+0.005cv_{\rm out}=0.319^{+0.005}_{-0.008}c in addition to a relativistic disk reflection component in a poorly studied NLS1 WKK~4438, based on archival \nustar and \suzaku observations. The spectra of both \suzaku and \nustar observations show an Fe~\textsc{xxvi} absorption feature and the \suzaku data also show evidence for an Ar~\textsc{xviii} with the same blueshift. A super-solar argon abundance (ZArβ€²>6ZβŠ™Z^{\prime}_{\rm Ar}>6Z_{\odot}) and a slight iron over-abundance (ZFeβ€²=2.6βˆ’2.0+1.9ZβŠ™Z^{\prime}_{\rm Fe}=2.6^{+1.9}_{-2.0}Z_{\odot}) are found in our spectral modelling. Based on Monte-Carlo simulations, the detection of the UFO is estimated to be around at 3Οƒ\sigma significance. The fast wind most likely arises from a radius of β‰₯20rg\geq20r_g away from the central black hole. The disk is accreting at a high Eddington ratio (Lbol=0.4βˆ’0.7LEddL_{\rm bol}=0.4-0.7L_{\rm Edd}). The mass outflow rate of the UFO is comparable with the disk mass inflow rate (MΛ™out>30%MΛ™in\dot M_{\rm out}>30\%\dot M_{\rm in}), assuming a maximum covering factor. The kinetic power of the wind might not be high enough to have influence in AGN feedback (EΛ™wind/Lbolβ‰ˆ3βˆ’5%\dot E_{\rm wind}/L_{\rm bol}\approx 3-5\%) due to a relatively small column density (12βˆ’4+9Γ—102212^{+9}_{-4}\times10^{22}~cmβˆ’2^{-2}). However note that both the inferred velocity and the column density could be lower limits owing to the low viewing angle (i=23βˆ’2+3i=23^{+3}_{-2}∘^{\circ}).Comment: 7 pages, 3 figures, accepted by MNRA

    E-learning for Critical Thinking: Using Nominal Focus Group Method to Inform Software Content and Design

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    Background: Undergraduate nursing students are often confused by multiple understandings of critical thinking. In response to this situation, the Critiique for critical thinking (CCT) project was implemented to provide consistent structured guidance about critical thinking. Objectives: This paper introduces Critiique software, describes initial validation of the content of this critical thinking tool and explores wider applications of the Critiique software. Materials and Methods: Critiique is flexible, authorable software that guides students step-by-step through critical appraisal of research papers. The spelling of Critiique was deliberate, so as to acquire a unique web domain name and associated logo. The CCT project involved implementation of a modified nominal focus group process with academic staff working together to establish common understandings of critical thinking. Previous work established a consensus about critical thinking in nursing and provided a starting point for the focus groups. The study was conducted at an Australian university campus with the focus group guided by open ended questions. Results: Focus group data established categories of content that academic staff identified as important for teaching critical thinking. This emerging focus group data was then used to inform modification of Critiique software so that students had access to consistent and structured guidance in relation to critical thinking and critical appraisal. Conclusions: The project succeeded in using focus group data from academics to inform software development while at the same time retaining the benefits of broader philosophical dimensions of critical thinking

    Improved Constraints on Isotropic Shift and Anisotropies of the Speed of Light using Rotating Cryogenic Sapphire Oscillators

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    We demonstrate that Michelson-Morley tests, which detect direction-dependent anisotropies in the speed of light, can also be used to place limits upon isotropic deviations of the vacuum speed of light from cc, as described by the photon sector Standard Model Extension (SME) parameter ΞΊ~tr\tilde{\kappa}_{tr}. A shift in the speed of light that is isotropic in one inertial frame implies anisotropic shifts in others. Using observer Lorentz covariance, we derive the time-dependent variations in the relative resonance frequencies of a pair of electromagnetic resonators that would be generated by such a shift in the rest frame of the Sun. A new analysis of a recent experimental test of relativity using this result constrains ΞΊ~tr\tilde{\kappa}_{tr} with a precision of 7.4Γ—10βˆ’97.4\times10^{-9}. This represents the first constraint on ΞΊ~tr\tilde{\kappa}_{tr} by a Michelson-Morley experiment and the first analysis of a single experiment to simultaneously set limits on all nine non-birefringent terms in the photon sector of the SME

    Homoiterons and expansion in ribosomal RNAs

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    AbstractRibosomal RNAs in both prokaryotes and eukaryotes feature numerous repeats of three or more nucleotides with the same nucleobase (homoiterons). In prokaryotes these repeats are much more frequent in thermophile compared to mesophile or psychrophile species, and have similar frequency in both large RNAs. These features point to use of prokaryotic homoiterons in stabilization of both ribosomal subunits. The two large RNAs of eukaryotic cytoplasmic ribosomes have expanded to a different degree across the evolutionary ladder. The big RNA of the larger subunit (60S LSU) evolved expansion segments of up to 2400 nucleotides, and the smaller subunit (40S SSU) RNA acquired expansion segments of not more than 700 nucleotides. In the examined eukaryotes abundance of rRNA homoiterons generally follows size and nucleotide bias of the expansion segments, and increases with GC content and especially with phylogenetic rank. Both the nucleotide bias and frequency of homoiterons are much larger in metazoan and angiosperm LSU compared to the respective SSU RNAs. This is especially pronounced in the tetrapod vertebrates and seems to culminate in the hominid mammals. The stability of secondary structure in polyribonucleotides would significantly connect to GC content, and should also relate to G and C homoiteron content. RNA modeling points to considerable presence of homoiteron-rich double-stranded segments especially in vertebrate LSU RNAs, and homoiterons with four or more nucleotides in the vertebrate and angiosperm LSU RNAs are largely confined to the expansion segments. These features could mainly relate to protein export function and attachment of LSU to endoplasmic reticulum and other subcellular networks

    The GEEC2 spectroscopic survey of Galaxy Groups at 0.8<z<10.8<z<1

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    We present the data release of the Gemini-South GMOS spectroscopy in the fields of 11 galaxy groups at 0.8<z<10.8<z<1, within the COSMOS field. This forms the basis of the Galaxy Environment Evolution Collaboration 2 (GEEC2) project to study galaxy evolution in haloes with M∼1013MβŠ™M\sim 10^{13}M_\odot across cosmic time. The final sample includes 162162 spectroscopically--confirmed members with R50R50 per cent complete for galaxies within the virial radius, and with stellar mass Mstar>1010.3MβŠ™M_{\rm star}>10^{10.3}M_\odot. Including galaxies with photometric redshifts we have an effective sample size of ∼400\sim 400 galaxies within the virial radii of these groups. We present group velocity dispersions, dynamical and stellar masses. Combining with the GCLASS sample of more massive clusters at the same redshift we find the total stellar mass is strongly correlated with the dynamical mass, with log⁑M200=1.20(log⁑Mstarβˆ’12)+14.07\log{M_{200}}=1.20\left(\log{M_{\rm star}}-12\right)+14.07. This stellar fraction of  ∼1~\sim 1 per cent is lower than predicted by some halo occupation distribution models, though the weak dependence on halo mass is in good agreement. Most groups have an easily identifiable most massive galaxy (MMG) near the centre of the galaxy distribution, and we present the spectroscopic properties and surface brightness fits to these galaxies. The total stellar mass distribution in the groups, excluding the MMG, compares well with an NFW profile with concentration 44, for galaxies beyond ∼0.2R200\sim 0.2R_{200}. This is more concentrated than the number density distribution, demonstrating that there is some mass segregation.Comment: Accepted for publication in MNRAS. The appendix is omitted due to large figures. The full version will be available from the MNRAS website and from http://quixote.uwaterloo.ca/~mbalogh/papers/GEEC2_data.pdf. Long data tables are available from MNRAS or by contacting the first autho
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