1,096 research outputs found

    Overcoming change fatigue: lessons from Glasgow's National Health Service

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    Structured Abstract Purpose of this paper This paper explores the practicalities of organizational change in complex settings where much change has already occurred. It therefore offers insights into tackling and overcoming change fatigue. Design/methodology/approach The paper uses a longitudinal study of change within a healthcare organization. The paper draws on interviews, focus groups and observations during a 2.5 year long action research project. Findings The paper reports findings on the speed at which change takes place, the importance of communication and the burden placed on senior officers during such communication and consultation processes, the use of appropriate external resources and expertise, the benefits of sharing best practice across sectors and the role of academic researchers in change processes. What is original/value of paper The paper offers valuable insights to those charged with effecting organizational change in change fatigued settings

    Direct Imaging of Multiple Planets Orbiting the Star HR 8799

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    Direct imaging of exoplanetary systems is a powerful technique that can reveal Jupiter-like planets in wide orbits, can enable detailed characterization of planetary atmospheres, and is a key step towards imaging Earth-like planets. Imaging detections are challenging due to the combined effect of small angular separation and large luminosity contrast between a planet and its host star. High-contrast observations with the Keck and Gemini telescopes have revealed three planets orbiting the star HR 8799, with projected separations of 24, 38, and 68 astronomical units. Multi-epoch data show counter-clockwise orbital motion for all three imaged planets. The low luminosity of the companions and the estimated age of the system imply planetary masses between 5 and 13 times that of Jupiter. This system resembles a scaled-up version of the outer portion of our Solar System.Comment: 30 pages, 5 figures, Research Article published online in Science Express Nov 13th, 200

    Magnon softening in a ferromagnetic monolayer: a first-principles spin dynamics study

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    We study the Fe/W(110) monolayer system through a combination of first principles calculations and atomistic spin dynamics simulations. We focus on the dispersion of the spin waves parallel to the [001] direction. Our results compare favorably with the experimental data of Prokop et al. [Phys. Rev. Lett. 102, 177206], and correctly capture a drastic softening of the magnon spectrum, with respect to bulk bcc Fe. The suggested shortcoming of the itinerant electron model, in particular that given by density functional theory, is refuted. We also demonstrate that finite temperature effects are significant, and that atomistic spin dynamics simulations represent a powerful tool with which to include these.Comment: v1: 11 pages, 3 figures. v2: double column, 5 pages, 3 figures, typos corrected, references adde

    Discovery of a 66 mas Ultracool Binary with Laser Guide Star Adaptive Optics

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    We present the discovery of 2MASS J21321145+1341584AB as a closely separated (0.066") very low-mass field dwarf binary resolved in the near-infrared by the Keck II Telescope using laser guide star adaptive optics. Physical association is deduced from the angular proximity of the components and constraints on their common proper motion. We have obtained a near-infrared spectrum of the binary and find that it is best described by an L5+/-0.5 primary and an L7.5+/-0.5 secondary. Model-dependent masses predict that the two components straddle the hydrogen burning limit threshold with the primary likely stellar and the secondary likely substellar. The properties of this sytem - close projected separation (1.8+/-0.3 AU) and near unity mass ratio - are consistent with previous results for very low-mass field binaries. The relatively short estimated orbital period of this system (~7-12 yr) makes it a good target for dynamical mass measurements. Interestingly, the system's angular separation is the tightest yet for any very low-mass binary published from a ground-based telescope and is the tightest binary discovered with laser guide star adaptive optics to date.Comment: 10 pages, 3 figures; accepted for publication to A

    A new 1.6-micron map of Titan’s surface

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    We present a new map of Titan's surface obtained in the spectral 'window' at ∼1.6 μm between strong methane absorption. This pre-Cassini view of Titan's surface was created from images obtained using adaptive optics on the W.M. Keck II telescope and is the highest resolution map yet made of Titan's surface. Numerous surface features down to the limits of the spatial resolution (∼200–300 km) are apparent. No features are easily identifiable in terms of their geologic origin, although several are likely craters

    The VAST Survey - IV. A wide brown dwarf companion to the A3V star ζ\zeta Delphini

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    We report the discovery of a wide co-moving substellar companion to the nearby (D=67.5±1.1D=67.5\pm1.1 pc) A3V star ζ\zeta Delphini based on imaging and follow-up spectroscopic observations obtained during the course of our Volume-limited A-Star (VAST) multiplicity survey. ζ\zeta Del was observed over a five-year baseline with adaptive optics, revealing the presence of a previously-unresolved companion with a proper motion consistent with that of the A-type primary. The age of the ζ\zeta Del system was estimated as 525±125525\pm125 Myr based on the position of the primary on the colour-magnitude and temperature-luminosity diagrams. Using intermediate-resolution near-infrared spectroscopy, the spectrum of ζ\zeta Del B is shown to be consistent with a mid-L dwarf (L5±25\pm2), at a temperature of 1650±2001650\pm200 K. Combining the measured near-infrared magnitude of ζ\zeta Del B with the estimated temperature leads to a model-dependent mass estimate of 50±1550\pm15 MJup_{\rm Jup}, corresponding to a mass ratio of q=0.019±0.006q=0.019\pm0.006. At a projected separation of 910±14910\pm14 au, ζ\zeta Del B is among the most widely-separated and extreme-mass ratio substellar companions to a main-sequence star resolved to-date, providing a rare empirical constraint of the formation of low-mass ratio companions at extremely wide separations.Comment: 12 pages, 11 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society, 2014 September 25. Revised to incorporate typographical errors noted during the proofing proces

    The VAST Survey - III. The multiplicity of A-type stars within 75 pc

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    With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D \le 75 pc) multiplicity survey of A-type stars, sensitive to companions beyond 30 au. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45,000 au. A total of 137 stellar companions were resolved, including 64 new detections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value of 387 (+132,-98) au. Integrating the fit to the distribution over the 30 to 10,000 au observed range, the companion star fraction for A-type stars is estimated as 33.8%+-2.6%. The mass ratio distribution of closer (<125 au) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9%+-7.0%. The most complete assessment of higher order multiples was estimated from the 156-star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of 56.4 (-4.0,+3.8), 32.1 (-3.5,+3.9), 9.0 (-1.8,+2.8), 1.9 (-0.6,+1.8) and 0.6 (-0.2,+1.4) per cent, respectively.Comment: 46 pages, 24 figures. Accepted for publication in the Monthly Notices of the Royal Astronomical Society, 7th October 201
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