2 results
The MeerKAT telescope as a pulsar facility: System verification and early science results from MeerTime
- M. Bailes, A. Jameson, F. Abbate, E. D. Barr, N. D. R. Bhat, L. Bondonneau, M. Burgay, S. J. Buchner, F. Camilo, D. J. Champion, I. Cognard, P. B. Demorest, P. C. C. Freire, T. Gautam, M. Geyer, J.-M. Griessmeier, L. Guillemot, H. Hu, F. Jankowski, S. Johnston, A. Karastergiou, R. Karuppusamy, D. Kaur, M. J. Keith, M. Kramer, J. van Leeuwen, M. E. Lower, Y. Maan, M. A. McLaughlin, B. W. Meyers, S. Osłowski, L. S. Oswald, A. Parthasarathy, T. Pennucci, B. Posselt, A. Possenti, S. M. Ransom, D. J. Reardon, A. Ridolfi, C. T. G. Schollar, M. Serylak, G. Shaifullah, M. Shamohammadi, R. M. Shannon, C. Sobey, X. Song, R. Spiewak, I. H. Stairs, B. W. Stappers, W. van Straten, A. Szary, G. Theureau, V. Venkatraman Krishnan, P. Weltevrede, N. Wex, T. D. Abbott, G. B. Adams, J. P. Burger, R. R. G. Gamatham, M. Gouws, D. M. Horn, B. Hugo, A. F. Joubert, J. R. Manley, K. McAlpine, S. S. Passmoor, A. Peens-Hough, Z. R Ramudzuli, A. Rust, S. Salie, L. C. Schwardt, R. Siebrits, G. Van Tonder, V. Van Tonder, M. G. Welz
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- Journal:
- Publications of the Astronomical Society of Australia / Volume 37 / 2020
- Published online by Cambridge University Press:
- 15 July 2020, e028
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- Article
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We describe system verification tests and early science results from the pulsar processor (PTUSE) developed for the newly commissioned 64-dish SARAO MeerKAT radio telescope in South Africa. MeerKAT is a high-gain ( ${\sim}2.8\,\mbox{K Jy}^{-1}$ ) low-system temperature ( ${\sim}18\,\mbox{K at }20\,\mbox{cm}$ ) radio array that currently operates at 580–1 670 MHz and can produce tied-array beams suitable for pulsar observations. This paper presents results from the MeerTime Large Survey Project and commissioning tests with PTUSE. Highlights include observations of the double pulsar $\mbox{J}0737{-}3039\mbox{A}$ , pulse profiles from 34 millisecond pulsars (MSPs) from a single 2.5-h observation of the Globular cluster Terzan 5, the rotation measure of Ter5O, a 420-sigma giant pulse from the Large Magellanic Cloud pulsar PSR $\mbox{J}0540{-}6919$ , and nulling identified in the slow pulsar PSR J0633–2015. One of the key design specifications for MeerKAT was absolute timing errors of less than 5 ns using their novel precise time system. Our timing of two bright MSPs confirm that MeerKAT delivers exceptional timing. PSR $\mbox{J}2241{-}5236$ exhibits a jitter limit of $<4\,\mbox{ns h}^{-1}$ whilst timing of PSR $\mbox{J}1909{-}3744$ over almost 11 months yields an rms residual of 66 ns with only 4 min integrations. Our results confirm that the MeerKAT is an exceptional pulsar telescope. The array can be split into four separate sub-arrays to time over 1 000 pulsars per day and the future deployment of S-band (1 750–3 500 MHz) receivers will further enhance its capabilities.
3 - WISC-IV test performance in the South African context: a collation of cross-cultural norms
- from Section One - Cognitive tests: conceptual and practical applications
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- By A. B. Shuttleworth-Edwards, Rhodes University, A. S. van der Merwe, Rhodes University, P. van Tonder, Rhodes University, S. E. Radloff, Rhodes University
- Edited by Sumaya Laher, Kate Cockcroft
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- Book:
- Psychological Assessment in South Africa
- Published by:
- Wits University Press
- Published online:
- 21 April 2018
- Print publication:
- 31 December 2013, pp 33-47
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Summary
The Wechsler Intelligence Scales have led the way in assessment of intelligence for almost seven decades, since the release of the original Wechsler-Bellevue Intelligence Scale in 1939 (Saklofske, Weiss, Beal & Coalson, 2003). Despite exemplary characteristics of other new and revised versions of intelligence tests, the Wechsler tests remain, and in the foreseeable future are likely to remain, the most widely used standardised measures for individual testing of children and adults worldwide, covering the age range from 2.5 to 89 years (Flanagan & Kaufman, 2009). The intermediate age ranges are catered for by the Wechsler Intelligence Scale for Children (WISC) which, when first released in 1949, marked the division of the Wechsler Intelligence Scales into separate tests for children and adults (Saklofske et al., 2003).
The WISC has gone through two previous revisions (WISC-R, 1974; WISCIII, 1991) prior to the most recently released version of the WISC-IV (Wechsler, 2003; 2004) that is intended for use with children aged 6 years to 16 years 11 months. The current version of the test was revised to keep up with changes in norms as population scores become inflated over time (known as the Flynn effect), as well as to ensure that test items remain current and unbiased (Prifitera, Weiss, Saklofske & Rolfhus, 2005). It also encompasses a fundamental theoretical shift, as it was designed with current trends in factor analysis theories in mind and thereby is considered to have introduced stronger psychometric properties (Baron, 2005). The test remains a good measure of g (the general intelligence factor) and consistently measures the same constructs across age groups 6 to 16 (Keith, Fine, Taub, Reynolds & Kranzler, 2006). The results of the US standardisation confirmed that the WISC-IV achieved high levels of reliability, with test-retest reliability being at least .76, but mostly in the .80s, and with subtest scores being less stable compared to Index scores and the Full Scale Intelligence Quotient (FSIQ); convergent validity with preceding editions of the Wechsler tests, including the WISC-III, yielded correlations from at least .73, but mostly in the high .70s and high .80s (Wechsler, 2003).
Based on new neurological models of cognitive function, the WISC-IV's main departure from the traditional Wechsler model is that it improves on the test's ability to evaluate perceptual reasoning, working memory and processing speed (Wechsler, 2003).