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- van Haarlem, M. P., et al.
(författare)
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LOFAR : The LOw-Frequency ARray
- 2013
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 556, s. 1-53
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Tidskriftsartikel (refereegranskat)abstract
- LOFAR, the LOw-Frequency ARray, is a new-generation radio interferometer constructed in the north of the Netherlands and across europe. Utilizing a novel phased-array design, LOFAR covers the largely unexplored low-frequency range from 10–240 MHz and provides a number of unique observing capabilities. Spreading out from a core located near the village of Exloo in the northeast of the Netherlands, a total of 40 LOFAR stations are nearing completion. A further five stations have been deployed throughout Germany, and one station has been built in each of France, Sweden, and the UK. Digital beam-forming techniques make the LOFAR system agile and allow for rapid repointing of the telescope as well as the potential for multiple simultaneous observations. With its dense core array and long interferometric baselines, LOFAR achieves unparalleled sensitivity and angular resolution in the low-frequency radio regime. The LOFAR facilities are jointly operated by the International LOFAR Telescope (ILT) foundation, as an observatory open to the global astronomical community. LOFAR is one of the first radio observatories to feature automated processing pipelines to deliver fully calibrated science products to its user community. LOFAR’s new capabilities, techniques and modus operandi make it an important pathfinder for the Square Kilometre Array (SKA). We give an overview of the LOFAR instrument, its major hardware and software components, and the core science objectives that have driven its design. In addition, we present a selection of new results from the commissioning phase of this new radio observatory.
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| 2. |
- Nilsagård, Ylva, 1964-, et al.
(författare)
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Functional gait assessment : Reliability and validity in people with peripheral vestibular disorders
- 2014
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Ingår i: International Journal of Therapy and Rehabilitation. - : MA Healthcare Ltd. - 1741-1645 .- 1759-779X. ; 21:8, s. 367-373
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Tidskriftsartikel (refereegranskat)abstract
- Background/aim: Reliable and valid measures evaluating imbalance during walking are important for targeting rehabilitation efforts. This study aimed to investigate the reliability and validity of the Functional Gait Assessment (FGA) in people with peripheral vestibular disorder.Methods: This study used a cross-sectional design and tested the reliability and validity of the FGA in 43 participants with peripheral vestibular disorder. The participants' performance on the FGA was filmed. To test intra-rater reliability, three raters reassessed 39 of these participants using the video uptakes. Interrater reliability was assessed by five raters analysing the video uptakes. Concurrent validity was investigated using timed measures of dynamic balance and the Activities-specific Balance Confidence scale.Results: The intra-rater reliability for the FGA score was high, with a intraclass correlation coefficient (ICC) (model 2,1)=0.94 (95% CI=0.85; 0.97). The intra-rater percentage of agreement for all raters for separate items was moderate to high, and weighted kappa was good to very good, ranging from 0.61 for change in speed to 0.95 for stair climbing. The inter-rater reliability was ICC (model 2,1)=0.73 (95% CI=0.49; 0.86). Agreement for two random raters was 45-92%. Weighted kappa was fair to very good, ranging from 0.27 for change in speed to 0.87 for walking with a narrow base of support. The internal consistency was high (α=0.88). Gait with eyes closed had the lowest item-to-total (0.33) and item-to-item (<0.30) correlation. Concurrent validity was moderate to strong (rho=0.50-0.76) with the highest correlation coefficient for the Timed Up and Go test.Conclusions: The FGA is a reliable and valid measure in people with peripheral vestibular disorder. For improving internal consistency, removal of the item 'gait with eyes closed' may be considered.
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