A new approach to achieving diffraction limited imaging in the visible from ground-based telescopes is described. It uses lucky image selection to choose the sharpest images from a sequence taken at ...high speed. When used behind a low order adaptive optics system it is possible to work with much larger diameter telescopes than would normally be expected. A further development involving aperture segmentation and image re-synthesis promises to allow these techniques to be extended to even larger telescopes.
We present the first detection of a gravitational depletion signal at near-infrared wavelengths, based on deep panoramic images of the cluster Abell 2219 (z=0.22) taken with the Cambridge Infrared ...Survey Instrument (CIRSI) at the prime focus of the 4.2-m William Herschel Telescope. Infrared studies of gravitational depletion offer a number of advantages over similar techniques applied at optical wavelengths, and can provide reliable total masses for intermediate-redshift clusters. Using the maximum-likelihood technique developed by Schneider, King & Erben, we detect the gravitational depletion at the 3σ confidence level. By modelling the mass distribution as a singular isothermal sphere and ignoring the uncertainty in the unlensed number counts, we find an Einstein radius of (66 per cent confidence limit). This corresponds to a projected velocity dispersion of σ
ν
∼800 km s−1, in agreement with constraints from strongly lensed features. For a Navarro, Frenk & White mass model, the radial dependence observed indicates a best-fitting halo scalelength of 125h
−1 kpc. We investigate the uncertainties arising from the observed fluctuations in the unlensed number counts, and show that clustering is the dominant source of error. We extend the maximum-likelihood method to include the effect of incompleteness, and discuss the prospects of further systematic studies of lensing in the near-infrared band.
This study investigates the use of Model Predictive Control (MPC) for regulation of river flows. During the past decade, MPC has emerged for controlling open water systems, such as irrigation and ...drainage channels. Compared to a full river network, irrigation and drainage systems are of relatively small scale. The aim of the present work is to investigate MPC as a tool for control of releases from gates and dams in a large-scale river network using the Murrumbidgee River in New South Wales, Australia, as case study. The Murrumbidgee River has around 1300 kilometers of river reaches, and the travel time through the valley is of the order of one month. The research has focused on four points: 1) Configuring linear surrogate models to describe the characteristics of reaches and weir pools; 2) Formulating the control problem and its objectives; 3) Using MPC with a receding horizon to solve the control problem; and 4) Testing the accuracy of the calculated control action, by using it as forcing in a detailed hydraulic model. The tests show that a reliable computation of optimal releases from regulators throughout the river is obtained, despite the linear approximation of the dynamics. The tests also show that the computation time for setting up and solving the optimization problem is no more than a few minutes on today's laptops.
DIVISION IX / COMMISSION 9 / WORKING GROUP DETECTORS Abbott, Timothy M. C.; Crabtree, Dennis; Mackay, Craig D. ...
Proceedings of the International Astronomical Union,
12/2007, Letnik:
3, Številka:
T26B
Journal Article
Recenzirano
Odprti dostop
The same general claims hold true as in the last report and the field is as busy as ever. Community focus is on the deployment of large mosaics (up to 108 pixels) to telescopes, the pursuit of ...programs to build next generation mosaics (of order 109 pixels), and the investigation of novel variations in CCD design.
Background The Scottish Intercollegiate Guideline Network (SIGN) published Postoperative Management in Adults in 2004, advocating post‐operative assessments to optimize post‐operative care. Our aim ...was to improve post‐operative assessments in a surgical high‐dependency unit (HDU).
Methods A prospective audit of post‐operative admissions to surgical HDU over two 4‐week periods was performed. Medical and nursing documentations were reviewed. A tailored multi‐modal approach targeting specific barriers to change was used to implement changes; education of staff, introduction of designated HDU bleeps and a post‐operative assessment pro forma. Re‐audit was performed after 6 months.
Main findings The first cycle included 72 patients and the second included 62 patients. Time to assessment improved after changes. Forty‐six (74%) patients compared with 27 (37%) patients before were assessed within 4 hours. The number of individual reviews increased and number of reviews due to nursing concerns decreased. Thirty‐eight (61%) patients compared with 15 (21%) patients before were assessed through an individual review and one (2%) patient compared with 23 (32%) patients due to nursing concerns. Documentation improved. Documentation of relevant past medical history, medications, allergies, complications and post‐operative instructions improved from 2 (3%), 1 (1%), 0, 8 (11%) and 26 (36%), to 18 (29%), 28 (45%), 20 (32%), 18 (29%) and 55 (89%), respectively. Difference between first and second cycles was highly significant throughout (P < 0.001).
Conclusion Clinical practice was improved by a tailored multi‐modal approach. Educating staff, improving communication and documentation, and re‐audit has shown significant improvement. However, further improvements are required to reach best practice.
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