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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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.
AIDS, drought, and child malnutrition in southern Africa
- John B Mason, Adam Bailes, Karen E Mason, Olivia Yambi, Urban Jonsson, Claudia Hudspeth, Peter Hailey, Andrea Kendle, Dominique Brunet, Pierre Martel
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- Journal:
- Public Health Nutrition / Volume 8 / Issue 6 / September 2005
- Published online by Cambridge University Press:
- 02 January 2007, pp. 551-563
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Objective
To investigate trends in child malnutrition in six countries in southern Africa, in relation to the HIV epidemic and drought in crop years 2001/2 and 2002/3.
DesignEpidemiological analysis of sub-national and national surveys with related data.
SettingData from Lesotho, Malawi, Mozambique, Swaziland, Zambia and Zimbabwe, compiled and analysed under UNICEF auspices.
SubjectsSecondary data: children 0–5 years for weight-for-age; HIV prevalence data from various sources especially antenatal clinic surveillance.
ResultsChild nutritional status as measured by prevalence of underweight deteriorated from 2001 onwards in all countries except Lesotho, with very substantial increases in some provinces/districts (e.g. from 5 to 20% in Maputo (Mozambique, 1997–2002), 17 to 32% in Copperbelt (Zambia, 1999–2001/2) and 11 to 26% in Midlands province (Zimbabwe, 1999–2002)). Greater deterioration in underweight occurred in better-off areas. Areas with higher HIV/AIDS prevalences had (so far) lower malnutrition rates (and infant mortality rates), presumably because more modern areas – with greater reliance on trade and wage employment – have more HIV/AIDS. Areas with higher HIV/AIDS showed more deterioration in child nutrition. A significant area-level interaction was found of HIV/AIDS with the drought period, associated with particularly rapid deterioration in nutritional status.
ConclusionsFirst, the most vulnerable may be households in more modern areas, nearer towns, to whom resources need to be directed. Second, the causes of this vulnerability need to be investigated. Third, HIV/AIDS amplifies the effect of drought on nutrition, so rapid and effective response will be crucial if drought strikes again. Fourth, expanded nutritional surveillance is now needed to monitor and respond to deteriorating trends. Finally, with or without drought, new means are needed of bringing help, comfort and assistance to the child population.
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