12,224 research outputs found

    The final two redshifts for radio sources from the equatorial BRL sample

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    Best, Rottgering and Lehnert (1999, 2000a) defined a new sample of powerful radio sources from the Molonglo Reference Catalogue, for which redshifts were compiled or measured for 177 of the 178 objects. For the final object, MRC1059-010 (3C249), the host galaxy is here identified using near-infrared imaging, and the redshift is determined from VLT spectroscopy. For one other object in the sample, MRC0320+053 (4C05.14), the literature redshift has been questioned: new spectroscopic observations of this object are presented, deriving a corrected redshift. With these two results, the spectroscopic completeness of this sample is now 100%. New redshifts are also presented for PKS0742+10 from the Wall & Peacock 2.7 GHz catalogue, and PKS1336+003 from the Parkes Selected Regions. PKS0742+10 shows a strong neutral hydrogen absorption feature in its Lyman-alpha emission profile.Comment: 4 pages. LaTeX. Accepted for publication in MNRA

    FIFO Buffers in tie Sauce

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    International audienceThis paper introduces a new semantics for FIFO buffers (more usually called channels) in a parallel programming language, B(PN)ÂČ. This semantics is given in terms of M-nets, which form an algebra of labelled high-level Petri nets. The proposed approach makes usage of asynchronous link operator, newly introduced in the algebra of M-nets, and repairs some drawbacks of the previous M-net semantics. Channels are now fully expressible within the algebra (it was not the case), they are significantly smaller (in number of places), and they offer several other advantages

    The triggering probability of radio-loud AGN: A comparison of high and low excitation radio galaxies in hosts of different colors

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    Low luminosity radio-loud active galactic nuclei (AGN) are generally found in massive red elliptical galaxies, where they are thought to be powered through gas accretion from their surrounding hot halos in a radiatively inefficient manner. These AGN are often referred to as "low-excitation" radio galaxies (LERGs). When radio-loud AGN are found in galaxies with a young stellar population and active star formation, they are usually high-power radiatively-efficient radio AGN ("high-excitation", HERG). Using a sample of low-redshift radio galaxies identified within the Sloan Digital Sky Survey (SDSS), we determine the fraction of galaxies that host a radio-loud AGN, fRLf_{RL}, as a function of host galaxy stellar mass, M∗M_*, star formation rate, color (defined by the 4000 \angstrom break strength), radio luminosity and excitation state (HERG/LERG). We find the following: 1. LERGs are predominantly found in red galaxies. 2. The radio-loud AGN fraction of LERGs hosted by galaxies of any color follows a fRLLE∝M∗2.5f^{LE}_{RL} \propto M^{2.5}_* power law. 3. The fraction of red galaxies hosting a LERG decreases strongly for increasing radio luminosity. For massive blue galaxies this is not the case. 4. The fraction of green galaxies hosting a LERG is lower than that of either red or blue galaxies, at all radio luminosities. 5. The radio-loud AGN fraction of HERGs hosted by galaxies of any color follows a fRLHE∝M∗1.5f^{HE}_{RL} \propto M^{1.5}_* power law. 6. HERGs have a strong preference to be hosted by green or blue galaxies. 7. The fraction of galaxies hosting a HERG shows only a weak dependence on radio luminosity cut. 8. For both HERGs and LERGs, the hosting probability of blue galaxies shows a strong dependence on star formation rate. This is not observed in galaxies of a different color.[abridged]Comment: 7 pages, 6 figure

    Detoxification in rehabilitation in England: effective continuity of care or unhappy bedfellows?

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    There is evidence that residential detoxification alone does not provide satisfactory treatment outcomes and that outcomes are significantly enhanced when clients completing residential detoxification attend rehabilitation services (Gossop, Marsden, Stewart, & Rolfe, 1999; Ghodse, Reynolds, Baldacchino, et al., 2002). One way of increasing the likelihood of this continuity of treatment is by providing detoxification and rehabilitation within the same treatment facility to prevent drop-out, while the client awaits a rehabilitation bed or in the transition process. However, there is little research evidence available on the facilities that offer both medical detoxification and residential rehabilitation. The current study compares self-reported treatment provision in 87 residential rehabilitation services in England, 34 of whom (39.1%) reported that they offered detoxification services within their treatment programmes. Although there were no differences in self-reported treatment philosophies, residential rehabilitation services that offered detoxification were typically of shorter duration overall, had significantly more beds and reported offering more group work than residential rehabilitation services that did not offer detoxification. Outcomes were also different, with twice as many clients discharged on disciplinary grounds from residential rehabilitation services without detoxification facilities. The paper questions the UK classification of residential drug treatment services as either detoxification or rehabilitation and suggests the need for greater research focus on the aims, processes and outcomes of this group of treatment providers

    A jet-cloud interaction in 3C34 at redshift z = 0.69

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    We report the detection of a strong jet-cloud interaction at a distance of 120 kpc from the nucleus of the radio galaxy 3C34, which has redshift z=0.69. Hubble Space Telescope images of the radio galaxy show a long narrow region of blue emission orientated along the radio axis and directed towards a radio hotspot. The William Herschel Telescope has been used to provide long-slit spectroscopic data of this object, and infrared observations made with the United Kingdom InfraRed Telescope have enabled its spectral energy distribution to be modelled. We propose that the aligned emission is associated with a region of massive star-formation, induced by the passage of the radio jet through a galaxy within the cluster surrounding 3C34. A star-formation rate of about 100 solar masses per year is required, similar to the values necessary to produce the alignment effect in high-redshift radio galaxies. The consequences of this result for models of star formation in distant radio galaxies are discussed.Comment: 12 pages including 11 figures, LaTeX. To appear in MNRA

    HST, radio and infrared observations of 28 3CR radio galaxies at redshift z ~ 1: I. The observations

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    Hubble Space Telescope images are presented of a sample of 28 3CR radio galaxies with redshifts in the range 0.6 < z < 1.8, together with maps at comparable angular resolution of their radio structure, taken using the Very Large Array. Infrared images of the fields, taken with the United Kingdom InfraRed Telescope, are also presented. The optical images display a spectacular range of structures. Many of the galaxies show highly elongated optical emission aligned along the directions of the radio axes, but this is not a universal effect; a small number of sources are either symmetrical or misaligned. Amongst those sources which do show an alignment effect, the morphology of the optical emission varies greatly, from a single bright elongated emission region to strings of optical knots stretching from one radio hotspot to the other. The infrared images display much less complexity. Although their significantly lower angular resolution would wash out some of the smaller structures seen in the HST images, it is clear that these galaxies are less aligned at infrared wavelengths than in the optical. In this paper, we discuss the galaxies individually, but defer a statistical analysis of the multi-waveband properties of the complete sample of sources to later papers in this series.Comment: 39 pages including 52 figures, LaTeX. Accepted for publication in MNRA

    Evaluating the introduction of CBA into the learning, teaching and assessment strategy of the diagnostic radiography course at Sheffield Hallam University

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    feedback have been introduced into the BSc (Hons) Diagnostic Radiography course at Sheffield Hallam University (SHU). CBA was selected for a number of reasons: it is a natural progression of the current use of information technology (IT) in learning and teaching; it further develops essential IT skills; it allows real medical images to be viewed; it tests students prior to placement, therefore helping to ensure appropriate levels of knowledge and understanding, and consequently reducing the burden of supervising radiographers; students requiring additional tutor support will be identified at this stage; it is thought to be an efficient use of lecturer time; it is anticipated that there will be a reduction in potential biases surrounding the marking process; an ‘easy’ to use CBA system is readily available in SHU’s adopted virtual learning environment, Blackboard 5.5; SHUS’s IT infrastructure is more robust than ever before. Although CBA is only one method within a diverse overall learning, teaching and assessment strategy, it is new and innovative and is therefore being evaluated to assess the appropriateness and effectiveness of implementation
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