11,971 research outputs found

    Probing the cool ISM in galaxies via 21cm HI absorption

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    Recent targeted studies of associated HI absorption in radio galaxies are starting to map out the location, and potential cosmological evolution, of the cold gas in the host galaxies of Active Galactic Nuclei (AGN). The observed 21 cm absorption profiles often show two distinct spectral-line components: narrow, deep lines arising from cold gas in the extended disc of the galaxy, and broad, shallow lines from cold gas close to the AGN (e.g. Morganti et al. 2011). Here, we present results from a targeted search for associated HI absorption in the youngest and most recently-triggered radio AGN in the local universe (Allison et al. 2012b). So far, by using the recently commissioned Australia Telescope Compact Array Broadband Backend (CABB; Wilson et al. 2011), we have detected two new absorbers and one previously-known system. While two of these show both a broad, shallow component and a narrow, deep component (see Fig. 1), one of the new detections has only a single broad, shallow component. Interestingly, the host galaxies of the first two detections are classified as gas-rich spirals, while the latter is an early-type galaxy. These detections were obtained using a spectral-line finding method, based on Bayesian inference, developed for future large-scale absorption surveys (Allison et al. 2012a).Comment: 1 page, 1 figure, published in Proceedings of IAU Symposium No. 29

    Why we need interprofessional education to improve the delivery of safe and effective care

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    Interprofessional education (IPE) is an activity that involves two or more professions who learn interactively together to improve collaboration and the quality of care. Research has continually revealed that health and social care professionals encounter a range of problems with interprofessional coordination and collaboration which impact on the quality and safety of care. This empirical work resulted in policymakers across health care education and practice to invest in IPE to help resolve this collaborative failures. It is anticipated that IPE will provide health and social care professionals with the abilities required to work together effectively in providing safe high quality care to patients. Through a discussion of a range of key professional, educational and organization issues related to IPE, this paper argues that this form of education is an important strategy to improve the delivery of safe and effective care

    Shock Tube Determination of Autoionization Lifetime and Oscillator Strengths of the 352 3P 2Po-353P2 2S1/2 Doublet of Al I Scientific Report No. 2

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    Shock tube measurement of autoionization lifetime and oscillator strengths of states above first ionization potential for aluminu

    Direct Measurement of the X-ray Time-Delay Transfer Function in Active Galactic Nuclei

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    The origin of the observed time lags, in nearby active galactic nuclei (AGN), between hard and soft X-ray photons is investigated using new XMM-Newton data for the narrow-line Seyfert I galaxy Ark 564 and existing data for 1H0707-495 and NGC 4051. These AGN have highly variable X-ray light curves that contain frequent, high peaks of emission. The averaged light curve of the peaks is directly measured from the time series, and it is shown that (i) peaks occur at the same time, within the measurement uncertainties, at all X-ray energies, and (ii) there exists a substantial tail of excess emission at hard X-ray energies, which is delayed with respect to the time of the main peak, and is particularly prominent in Ark 564. Observation (i) rules out that the observed lags are caused by Comptonization time delays and disfavors a simple model of propagating fluctuations on the accretion disk. Observation (ii) is consistent with time lags caused by Compton-scattering reverberation from material a few thousand light-seconds from the primary X-ray source. The power spectral density and the frequency-dependent phase lags of the peak light curves are consistent with those of the full time series. There is evidence for non-stationarity in the Ark 564 time series in both the Fourier and peaks analyses. A sharp `negative' lag (variations at hard photon energies lead soft photon energies) observed in Ark 564 appears to be generated by the shape of the hard-band transfer function and does not arise from soft-band reflection of X-rays. These results reinforce the evidence for the existence of X-ray reverberation in type I AGN, which requires that these AGN are significantly affected by scattering from circumnuclear material a few tens or hundreds of gravitational radii in extent.Comment: Accepted for publication in Ap

    An analysis of the XOR dynamic problem generator based on the dynamical system

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    This is the post-print version of the article - Copyright @ 2010 Springer-VerlagIn this paper, we use the exact model (or dynamical system approach) to describe the standard evolutionary algorithm (EA) as a discrete dynamical system for dynamic optimization problems (DOPs). Based on this dynamical system model, we analyse the properties of the XOR DOP Generator, which has been widely used by researchers to create DOPs from any binary encoded problem. DOPs generated by this generator are described as DOPs with permutation, where the fitness vector is changed according to a permutation matrix. Some properties of DOPs with permutation are analyzed, which allows explaining some behaviors observed in experimental results. The analysis of the properties of problems created by the XOR DOP Generator is important to understand the results obtained in experiments with this generator and to analyze the similarity of such problems to real world DOPs.This work was supported by Brazil FAPESP under Grant 04/04289-6 and by UK EPSRC under Grant EP/E060722/2

    Low-Altitude Reconnection Inflow-Outflow Observations during a 2010 November 3 Solar Eruption

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    For a solar flare occurring on 2010 November 3, we present observations using several SDO/AIA extreme-ultraviolet (EUV) passbands of an erupting flux rope followed by inflows sweeping into a current sheet region. The inflows are soon followed by outflows appearing to originate from near the termination point of the inflowing motion - an observation in line with standard magnetic reconnection models. We measure average inflow plane-of-sky speeds to range from ~150-690 km/s with the initial, high-temperature inflows being the fastest. Using the inflow speeds and a range of Alfven speeds, we estimate the Alfvenic Mach number which appears to decrease with time. We also provide inflow and outflow times with respect to RHESSI count rates and find that the fast, high-temperature inflows occur simultaneously with a peak in the RHESSI thermal lightcurve. Five candidate inflow-outflow pairs are identified with no more than a minute delay between detections. The inflow speeds of these pairs are measured to be 10^2 km/s with outflow speeds ranging from 10^2-10^3 km/s - indicating acceleration during the reconnection process. The fastest of these outflows are in the form of apparently traveling density enhancements along the legs of the loops rather than the loop apexes themselves. These flows could either be accelerated plasma, shocks, or waves prompted by reconnection. The measurements presented here show an order of magnitude difference between the retraction speeds of the loops and the speed of the density enhancements within the loops - presumably exiting the reconnection site.Comment: 31 pages, 13 figures, 1 table, Accepted to ApJ (expected publication ~July 2012

    How to identify when a performance indicator has run its course

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    The official published version can be found at the link below.Increasing numbers of countries are using indicators to evaluate the quality of clinical care, with some linking payment to achievement. For performance frameworks to remain effective the indicators need to be regularly reviewed. The frameworks cannot cover all clinical areas, and achievement on chosen indicators will eventually reach a ceiling beyond which further improvement is not feasible. However, there has been little work on how to select indictors for replacement. The Department of Health decided in 2008 that it would regularly replace indicators in the national primary care pay for performance scheme, the Quality and Outcomes Framework, making a rigorous approach to removal a priority. We draw on our previous work on pay for performance and our current work advising the National Institute for Health and Clinical Excellence (NICE) on the Quality and Outcomes Framework to suggest what should be considered when planning to remove indicators from a clinical performance framework
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