Author: "deSouza, L." / Publication Year Range: Last 50 years - Searchworks@Jio Institute Digital Library Search Results

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229 results on '"deSouza, L."'

1. Joblessness and Lost Earnings after Acute Respiratory Distress Syndrome in a 1-Year National Multicenter Study

Author: Kamdar, Biren B, Huang, Minxuan, Dinglas, Victor D, Colantuoni, Elizabeth, von Wachter, Till M, Hopkins, Ramona O, Needham, Dale M, Hudson, L, Gundel, S, Hough, C, Neff, M, Sims, K, Ungar, A, Watkins, T, Steingrub, J, Tidswell, M, Braden, E, DeSouza, L, Kardos, C, Kozikowski, L, Ouellette, S, Guntupalli, K, Bandi, V, Pope, C, Ross, C, Brower, R, Fessler, H, Hager, D, Mendez-Tellez, P, Needham, D, Oakjones, K, Sevransky, J, Workneh, A, Shanholtz, C, Herr, D, Howes, H, Netzer, G, Rock, P, Sampaio, A, Titus, J, Sloane, P, Beck, T, Highfield, D, King, S, Lee, B, Bolouri, N, Wiedemann, HP, Ashton, RW, Culver, DA, Frederick, T, Guzman, JA, Komara, JJ, Reddy, AJ, Hejal, R, Andrews, M, Haney, D, Connors, AF, Lasalvia, S, Thornton, JD, Warren, EL, Moss, M, Burnham, EL, Gray, L, Maloney, J, Mealer, M, Douglas, I, Overdier, K, Thompson, K, Wolken, R, Frankel, S, McKeehan, J, Warner, ML, Bost, T, Higgins, C, Hodgin, K, MacIntyre, N, Brown, L, Cox, C, Gentile, M, Govert, J, Knudsen, N, Carson, S, Chang, L, Choudhury, S, Hall, W, Lanier, J, Wheeler, AP, Bernard, GR, Hays, M, Mogan, S, Rice, TW, Hite, RD, Harvey, A, Morris, PE, Ragusky, M, Wright, P, Groce, S, McLean, J, Overton, A, and Truwit, J
Subjects: Biomedical and Clinical Sciences, Cardiovascular Medicine and Haematology, Clinical Sciences, Acute Respiratory Distress Syndrome, Rare Diseases, Lung, Adult, Critical Illness, Employment, Female, Humans, Income, Longitudinal Studies, Male, Middle Aged, Respiratory Distress Syndrome, Survivors, Time Factors, Unemployment, United States, employment, intensive care unit, income, health insurance, National Heart, Lung, and Blood Institute Acute Respiratory Distress Syndrome Network, Medical and Health Sciences, Respiratory System, Cardiovascular medicine and haematology, Clinical sciences
Abstract: RationaleFollowing acute respiratory distress syndrome (ARDS), joblessness is common but poorly understood.ObjectivesTo evaluate the timing of return to work after ARDS, and associated risk factors, lost earnings, and changes in healthcare coverage Methods: Over 12-month longitudinal follow-up, ARDS survivors from 43 U.S. ARDSNet hospitals provided employment and healthcare coverage data via structured telephone interviews. Factors associated with the timing of return to work were assessed using Fine and Gray regression analysis. Lost earnings were estimated using Bureau of Labor Statistics data.Measurements and main resultsOf 922 consenting survivors, 386 (42%) were employed before ARDS (56% male; mean ± SD age, 45 ± 13 yr), with seven dying by 12-month follow-up. Of 379 previously employed 12-month survivors, 166 (44%) were jobless at 12-month follow-up. Accounting for competing risks of death and retirement, half of enrolled and previously employed survivors returned to work by 13 weeks after hospital discharge, with 68% ever returning by 12 months. Delays in return to work were associated with longer hospitalization and older age among nonwhite survivors. Over 12-month follow-up, 274 (71%) survivors accrued lost earnings, averaging $26,949 ± $22,447 (60% of pre-ARDS annual earnings). Jobless survivors experienced a 14% (95% confidence interval, 5-22%; P = 0.002) absolute decrease in private health insurance (from 44% pre-ARDS) and a 16% (95% confidence interval, 7-24%; P
Published: 2017

2. The Murchison Widefield Array Correlator

Author: Ord, S. M., Crosse, B., Emrich, D., Pallot, D., Wayth, R. B., Clark, M. A., Tremblay, S. E., Arcus, W., Barnes, D., Bell, M., Bernardi, G., Bhat, N. D. R., Bowman, J. D., Briggs, F., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A. A., deSouza, L., Ewell-Wice, A., Feng, L., Goeke, R., Greenhill, L. J., Hazelton, B. J., Herne, D., Hewitt, J. N., Hindson, L., Hurley-Walker, H., Jacobs, D., Johnston-Hollitt, M., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Kudryavtseva, N., Lenc, E., Lonsdale, C. J., Lynch, M. J., McKinley, B., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Offringa, A., Pathikulangara, J., Pindor, B., Prabu, T., Procopio, P., Remillard, R. A., Riding, J., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Computer Science - Computational Engineering, Finance, and Science
Abstract: The Murchison Widefield Array (MWA) is a Square Kilometre Array (SKA) Precursor. The telescope is located at the Murchison Radio--astronomy Observatory (MRO) in Western Australia (WA). The MWA consists of 4096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays (FPGAs), and others by Graphics Processing Units (GPUs) housed in general purpose rack mounted servers. The correlation capability required is approximately 8 TFLOPS (Tera FLoating point Operations Per Second). The MWA has commenced operations and the correlator is generating 8.3 TB/day of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces., Comment: 17 pages, 9 figures. Accepted for publication in PASA. Some figures altered to meet astro-ph submission requirements
Published: 2015
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3. A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

Author: Bell, M. E., Murphy, T., Kaplan, D. L., Hancock, P., Gaensler, B. M., Banyer, J., Bannister, K., Trott, C., Hurley-Walker, N., Wayth, R. B., Macquart, J. -P., Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Briggs, F., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Goeke, R., Greenhill, L. J., Hazelton, B. J., Herne, D., Hewitt, J. N., Johnston-Hollitt, M., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Astrophysics of Galaxies, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. Fifty-one images were obtained that cover a field of view of 1430 deg^2 centred on Hydra A. The observations were obtained over three days in 2010 March and three days in 2011 April and May. The mean cadence of the observations was 26 minutes and there was additional temporal information on day and year timescales. We explore the variability of a sample of 105 low frequency radio sources within the field. Four bright (S > 6 Jy) candidate variable radio sources were identified that displayed low levels of short timescale variability (26 minutes). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the timescale of one year we find two sources that show significant variability. We attribute this variability to either refractive scintillation or intrinsic variability. No radio transients were identified and we place an upper limit on the surface density of sources rho < 7.5 x 10^-5 deg^-2 with flux densities > 5.5 Jy, and characteristic timescales of both 26 minutes and one year., Comment: 18 pages, 12 figures
Published: 2013
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4. The giant lobes of Centaurus A observed at 118 MHz with the Murchison Widefield Array

Author: McKinley, B., Briggs, F., Gaensler, B. M., Feain, I. J., Bernardi, G., Wayth, R. B., Johnston-Hollitt, M., Offringa, A. R., Arcus, W., Barnes, D. G., Bowman, J. D., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Goeke, R., Greenhill, L. J., Hazelton, B. J., Herne, D., Hewitt, J. N., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Oberoi, D., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118 MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A's giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature-temperature plots and spectral tomography. We find that the morphologies at 118 MHz and 1.4 GHz match very closely apart from an extra peak in the southern lobe at 118 MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially-averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that supports a value for the lobe age of between 10 and 80 Myr., Comment: 18 pages, 11 figures, accepted for publication in MNRAS
Published: 2013
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5. On the detection and tracking of space debris using the Murchison Widefield Array. I. Simulations and test observations demonstrate feasibility

Author: Tingay, S. J., Kaplan, D. L., McKinley, B., Briggs, F., Wayth, R. B., Hurley-Walker, N., Kennewell, J., Smith, C., Zhang, K., Arcus, W., Bhat, R., Emrich, D., Herne, D., Kudryavtseva, N., Lynch, M., Ord, S. M., Waterson, M., Barnes, D. G., Bell, M., Gaensler, B. M., Lenc, E., Bernardi, G., Greenhill, L. J., Kasper, J. C., Bowman, J. D., Jacobs, D., Bunton, J. D., deSouza, L., Koenig, R., Pathikulangara, J., Stevens, J., Cappallo, R. J., Corey, B. E., Kincaid, B. B., Kratzenberg, E., Lonsdale, C. J., McWhirter, S. R., Rogers, A. E. E., Salah, J. E., Whitney, A. R., Deshpande, A., Prabu, T., Shankar, N. Udaya, Srivani, K. S., Subrahmanyan, R., Ewall-Wice, A., Feng, L., Goeke, R., Morgan, E., Remillard, R. A., Williams, C. L., Hazelton, B. J., Morales, M. F., Johnston-Hollitt, M., Mitchell, D. A., Procopio, P., Riding, J., Webster, R. L., Wyithe, J. S. B., Oberoi, D., Roshi, A., Sault, R. J., and Williams, A.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Earth and Planetary Astrophysics
Abstract: The Murchison Widefield Array (MWA) is a new low frequency interferomeric radio telescope. The MWA is the low frequency precursor to the Square Kilometre Array (SKA) and is the first of three SKA precursors to be operational, supporting a varied science mission ranging from the attempted detection of the Epoch of Reionisation to the monitoring of solar flares and space weather. We explore the possibility that the MWA can be used for the purposes of Space Situational Awareness (SSA). In particular we propose that the MWA can be used as an element of a passive radar facility operating in the frequency range 87.5 - 108 MHz (the commercial FM broadcast band). In this scenario the MWA can be considered the receiving element in a bi-static radar configuration, with FM broadcast stations serving as non-cooperative transmitters. The FM broadcasts propagate into space, are reflected off debris in Earth orbit, and are received at the MWA. The imaging capabilities of the MWA can be used to simultaneously detect multiple pieces of space debris, image their positions on the sky as a function of time, and provide tracking data that can be used to determine orbital parameters. Such a capability would be a valuable addition to Australian and global SSA assets, in terms of southern and eastern hemispheric coverage. We provide a feasibility assessment of this proposal, based on simple calculations and electromagnetic simulations that shows the detection of sub-metre size debris should be possible (debris radius of >0.5 m to ~1000 km altitude). We also present a proof-of-concept set of observations that demonstrate the feasibility of the proposal, based on the detection and tracking of the International Space Station via reflected FM broadcast signals originating in south-west Western Australia. These observations broadly validate our calculations and simulations., Comment: 24 pages, 5 figures, accepted by The Astronomical Journal. Abstract abridged here due to character number limits
Published: 2013
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6. A 189 MHz, 2400 square degree polarization survey with the Murchison Widefield Array 32-element prototype

Author: Bernardi, G., Greenhill, L. J., Mitchell, D. A., Ord, S. M., Hazelton, B. J., Gaensler, B. M., de Oliveira-Costa, A., Morales, M. F., Shankar, N. Udaya, Subrahmanyan, R., Wayth, R. B., Lenc, E., Williams, C. L., Arcus, W., Arora, S. B., Barnes, D. G., Bowman, J. D., Briggs, F. H., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Goeke, R., Herne, D., Hewitt, J. N., Johnston-Hollitt, M., Kaplan, D., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Srivani, K. S., Stevens, J., Tingay, S. J., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., and Wyithe, J. S. B.
Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32-element prototype covering 2400 square degrees. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy/beam. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images and deconvolution of the point spread function through forward modeling. We present a point source catalogue down to a flux limit of 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8 \pm 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13 K, primarily with positive rotation measure values smaller than +10 rad/m^2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at 2^h30^m where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at $(\alpha,\delta) = (4^h,-27^\circ.6)$ in terms of three dimensional power spectra, Comment: 18 pages, 14 figures. Accepted for publication in ApJ. A version with high resolution figures is available at http://www.astro.rug.nl/~bernardi/32T_survey/32T_survey.pdf
Published: 2013
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7. The Murchison Widefield Array: solar science with the low frequency SKA Precursor

Author: Tingay, S. J., Oberoi, D., Cairns, I., Donea, A., Duffin, R., Arcus, W., Bernardi, G., Bowman, J. D., Briggs, F., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Gaensler, B. M., Goeke, R., Greenhill, L. J., Hazelton, B. J., Herne, D., Hewitt, J. N., Johnston-Hollitt, M., Kaplan, D. L., Kasper, J. C., Kennewell, J. A., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A, Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Udaya-Shankar, N., Srivani, K. S., Stevens, J., Subrahmanyan, R., Waterson, M., Wayth, R. B., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Solar and Stellar Astrophysics
Abstract: The Murchison Widefield Array is a low frequency (80 - 300 MHz) SKA Precursor, comprising 128 aperture array elements (known as tiles) distributed over an area of 3 km diameter. The MWA is located at the extraordinarily radio quiet Murchison Radioastronomy Observatory in the mid-west of Western Australia, the selected home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science goals include: 1) detection of fluctuations in the brightness temperature of the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of reionisation; 2) studies of Galactic and extragalactic processes based on deep, confusion-limited surveys of the full sky visible to the array; 3) time domain astrophysics through exploration of the variable radio sky; and 4) solar imaging and characterisation of the heliosphere and ionosphere via propagation effects on background radio source emission. This paper concentrates on the capabilities of the MWA for solar science and summarises some of the solar science results to date, in advance of the initial operation of the final instrument in 2013., Comment: 5 pages, 1 figure
Published: 2013
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8. Realisation of a low frequency SKA Precursor: The Murchison Widefield Array

Author: Tingay, S. J., Goeke, R., Hewitt, J. N., Morgan, E., Remillard, R. A, Williams, C. L., Bowman, J. D., Emrich, D., Ord, S. M., Booler, T., Crosse, B., Pallot, D., Arcus, W., Colegate, T., Hall, P. J., Herne, D., Lynch, M. J., Schlagenhaufer, F., Tremblay, S., Wayth, R. B., Waterson, M., Mitchell, D. A., Sault, R. J., Webster, R. L., Wyithe, J. S. B., Morales, M. F., Hazelton, B. J., Wicenec, A., Williams, A., Barnes, D., Bernardi, G., Greenhill, L. J., Kasper, J. C., Briggs, F., McKinley, B., Bunton, J. D., deSouza, L., Koenig, R., Pathikulangara, J., Stevens, J., Cappallo, R. J., Corey, B. E., Kincaid, B. B., Kratzenberg, E., Lonsdale, C. J., McWhirter, S. R., Rogers, A. E. E., Salah, J. E., Whitney, A. R., Deshpande, A., Prabu, T., Roshi, A., Udaya-Shankar, N., Srivani, K. S., Subrahmanyan, R., Gaensler, B. M., Johnston-Hollitt, M., Kaplan, D. L., and Oberoi, D.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Physics - Instrumentation and Detectors
Abstract: The Murchison Widefield Array is a low frequency (80 - 300 MHz) SKA Precursor, comprising 128 aperture array elements distributed over an area of 3 km diameter. The MWA is located at the extraordinarily radio quiet Murchison Radioastronomy Observatory in the mid-west of Western Australia, the selected home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science goals include: 1) detection of fluctuations in the brightness temperature of the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of reionisation; 2) studies of Galactic and extragalactic processes based on deep, confusion-limited surveys of the full sky visible to the array; 3) time domain astrophysics through exploration of the variable radio sky; and 4) solar imaging and characterisation of the heliosphere and ionosphere via propagation effects on background radio source emission. This paper will focus on a brief discussion of the as-built MWA system, highlighting several novel characteristics of the instrument, and a brief progress report (as of June 2012) on the final construction phase. Practical completion of the MWA is expected in November 2012, with commissioning commencing from approximately August 2012 and operations commencing near mid 2013. A brief description of recent science results from the MWA prototype instrument is given., Comment: 8 pages, Resolving the Sky - Radio Interferometry: Past, Present and Future - RTS2012, April 17-20, 2012, Manchester, UK
Published: 2012

9. Low Frequency Observations of the Moon with the Murchison Widefield Array

Author: McKinley, B., Briggs, F., Kaplan, D. L., Greenhill, L. J., Bernardi, G., Bowman, J. D., de Oliveira-Costa, A., Tingay, S. J., Gaensler, B. M., Oberoi, D., Johnston-Hollitt, M., Arcus, W., Barnes, D., Bunton, J. D., Cappallo, R. C., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Goeke, R., Hazelton, B. J., Herne, D., Hewitt, J. N., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morales, M. F., Morgan, E., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Cosmology and Nongalactic Astrophysics, Astrophysics - Earth and Planetary Astrophysics, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: A new generation of low frequency radio telescopes is seeking to observe the redshifted 21 cm signal from the Epoch of Reionization (EoR), requiring innovative methods of calibration and imaging to overcome the difficulties of widefield low frequency radio interferometry. Precise calibration will be required to separate the small expected EoR signal from the strong foreground emission at the frequencies of interest between 80 and 300 MHz. The Moon may be useful as a calibration source for detection of the EoR signature, as it should have a smooth and predictable thermal spectrum across the frequency band of interest. Initial observations of the Moon with the Murchison Widefield Array 32 tile prototype show that the Moon does exhibit a similar trend to that expected for a cool thermally emitting body in the observed frequency range, but that the spectrum is corrupted by reflected radio emission from Earth. In particular, there is an abrupt increase in the observed flux density of the Moon within the internationally recognised Frequency Modulated (FM) radio band. The observations have implications for future low frequency surveys and EoR detection experiments that will need to take this reflected emission from the Moon into account. The results also allow us to estimate the equivalent isotropic power emitted by the Earth in the FM band and to determine how bright the Earth might appear at metre wavelengths to an observer beyond our own solar system., Comment: 25 pages, 11 figures, to be published in The Astronomical Journal
Published: 2012
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10. The Murchison Widefield Array: the Square Kilometre Array Precursor at low radio frequencies

Author: Tingay, S. J., Goeke, R., Bowman, J. D., Emrich, D., Ord, S. M., Mitchell, D. A., Morales, M. F., Booler, T., Crosse, B., Pallot, D., Wicenec, A., Arcus, W., Barnes, D., Bernardi, G., Briggs, F., Burns, S., Bunton, J. D., Cappallo, R. J., Colegate, T., Corey, B. E., Deshpande, A., deSouza, L., Gaensler, B. M., Greenhill, L. J., Hall, J., Hazelton, B. J., Herne, D., Hewitt, J. N., Johnston-Hollitt, M., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McKinley, B., McWhirter, S. R., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Udaya-Shankar, N., Schlagenhaufer, F., Srivani, K. S., Stevens, J., Subrahmanyan, R., Tremblay, S., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80-300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3 km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised., Comment: Submitted to PASA. 11 figures, 2 tables
Published: 2012
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11. The EoR Sensitivity of the Murchison Widefield Array

Author: Beardsley, A. P., Hazelton, B. J., Morales, M. F., Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Briggs, F. H., Bunton, J. D., Cappallo, R. J., Corey, B. E., Deshpande, A., deSouza, L., Emrich, D., Gaensler, B. M., Goeke, R., Greenhill, L. J., Herne, D., Hewitt, J. N., Johnston-Hollitt, M., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Koenig, R., Kratzenberg, E., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morgan, E., Oberoi, D., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Using the final 128 antenna locations of the Murchison Widefield Array (MWA), we calculate its sensitivity to the Epoch of Reionization (EoR) power spectrum of red- shifted 21 cm emission for a fiducial model and provide the tools to calculate the sensitivity for any model. Our calculation takes into account synthesis rotation, chro- matic and asymmetrical baseline effects, and excludes modes that will be contaminated by foreground subtraction. For the fiducial model, the MWA will be capable of a 14{\sigma} detection of the EoR signal with one full season of observation on two fields (900 and 700 hours)., Comment: 5 pages, 4 figures, 1 table, Accepted for publication in MNRAS Letters. Supplementary material will be available in the published version, or by contacting the authors
Published: 2012
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12. A new layout optimization technique for interferometric arrays, applied to the MWA

Author: Beardsley, A. P., Hazelton, B. J., Morales, M. F., Cappallo, R. C., Goeke, R., Emrich, D., Lonsdale, C. J., Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Bunton, J. D., Corey, B. E., Deshpande, A., deSouza, L., Gaensler, B. M., Greenhill, L. J., Herne, D., Hewitt, J. N., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Koeing, R., Kratzenberg, E., Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morgan, E., Oberoi, D., Ord, S. M., Pathikulangara, J., Prabu, T., Remillard, R. A., Rogers, A. E. E., Roshi, A., Salah, J. E., Sault, R. J., Shankar, N. Uday, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., Williams, C. L., and Wyithe, J. S. B.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract: Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21 cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed---even at the remote Australian location of the MWA (Murchison Widefield Array) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhance the PSF sidelobes and reduce the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution, and snapshot PSF for this array choice., Comment: 12 pages, 6 figures, 1 table. Accepted for publication in MNRAS
Published: 2012
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13. Interferometric imaging with the 32 element Murchison Wide-field Array

Author: Ord, S. M., Mitchell, D. A., Wayth, R. B., Greenhill, L. J., Bernardi, G., Gleadow, S., Edgar, R. G., Clark, M. A., Allen, G., Arcus, W., Benkevitch, L., Bowman, J. D., Briggs, F. H., Bunton, J. D., Burns, S., Cappallo, R. J., Coles, W. A., Corey, B. E., deSouza, L., Doeleman, S. S., Derome, M., Deshpande, A., Emrich, D., Goeke, R., Gopalakrishna, M. R., Herne, D., Hewitt, J. N., Kamini, P. A., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C. J., Lynch, M. J., McWhirter, S. R., Madhavi, S., Matejek, M., Morales, M. F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A. E. E., Roshi, A., Salah, J. E., Schinkel, A., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Tingay, S. J., Vaccarella, A., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., and Williams, C.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: The Murchison Wide-field Array (MWA) is a low frequency radio telescope, currently under construction, intended to search for the spectral signature of the epoch of re-ionisation (EOR) and to probe the structure of the solar corona. Sited in Western Australia, the full MWA will comprise 8192 dipoles grouped into 512 tiles, and be capable of imaging the sky south of 40 degree declination, from 80 MHz to 300 MHz with an instantaneous field of view that is tens of degrees wide and a resolution of a few arcminutes. A 32-station prototype of the MWA has been recently commissioned and a set of observations taken that exercise the whole acquisition and processing pipeline. We present Stokes I, Q, and U images from two ~4 hour integrations of a field 20 degrees wide centered on Pictoris A. These images demonstrate the capacity and stability of a real-time calibration and imaging technique employing the weighted addition of warped snapshots to counter extreme wide field imaging distortions., Comment: Accepted for publication in PASP. This is the draft before journal typesetting corrections and proofs so does contain formatting and journal style errors, also has with lower quality figures for space requirements
Published: 2010
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14. The Murchison Widefield Array

Author: Mitchell, Daniel A., Greenhill, Lincoln J., Ord, Stephen M., Bernardi, Gianni, Wayth, Randall B., Edgar, Richard G., Clark, Michael A., Dal, Kevin, Pfister, Hanspeter, Gleadow, Stewart J., Arcus, W., Briggs, F. H., Benkevitch, L., Bowman, J. D., Bunton, J. D., Burns, S., Cappallo, R. J., Corey, B. E., de Oliveira-Costa, A., Desouza, L., Doeleman, S. S., Derome, M. F., Emrich, D., Glossop, M., Goeke, R., Krishna, M. R. Gopala, Hazelton, B., Herne, D. E., Hewitt, J. N., Kamini, P. A., Kaplan, D. L., Kasper, J. C., Kincaid, B. B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C. J., Lynch, M. J., Madhavi, S., Matejek, M., McWhirter, S. R., Morales, M. F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Salah, J. E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Tingay, S. J., Vaccarella, A., Waterson, M., Webster, R. L., Whitney, A. R., Williams, A., and Williams, C.
Subjects: Astrophysics - Instrumentation and Methods for Astrophysics
Abstract: It is shown that the excellent Murchison Radio-astronomy Observatory site allows the Murchison Widefield Array to employ a simple RFI blanking scheme and still calibrate visibilities and form images in the FM radio band. The techniques described are running autonomously in our calibration and imaging software, which is currently being used to process an FM-band survey of the entire southern sky., Comment: Accepted for publication in Proceedings of Science [PoS(RFI2010)016]. 6 pages and 3 figures. Presented at RFI2010, the Third Workshop on RFI Mitigation in Radio Astronomy, 29-31 March 2010, Groningen, The Netherlands
Published: 2010

15. Assessment of Plasma Proteomics Biomarker’s Ability to Distinguish Benign From Malignant Lung Nodules: Results of the PANOPTIC (Pulmonary Nodule Plasma Proteomic Classifier) Trial

Author: Silvestri, G.A., Leake, L., Mazzone, P., Beukemann, M., Midthun, D., McCarthy, P., Sigal, B., Deluca, T., Laberge, F., Fortin, B., Balaan, M., Dimitt, B., Pierre, A., Allison, F., Yarmus, L., Oakjones-Burgess, K., Tanner, N., Ettinger, N., Setchfield, T., Madtes, D., Hubbard, J., McConnell, W., Robinson, K., Lackey, A., Jacques, L., Kuo, E., Markland-Gentles, V., Massion, P., Muterspaug, A., Leach, J., Rothe, K., Rom, W., Pass, H., Sorenson, A., Chesnutt, A., Georgeson, A., Balekian, A., Fisher, J., Murali, R., Overton, A., Desai, N., Levesque, A., Krimsky, W., King, S., Vachani, A., Maletteri, K., Mileham, K., Carter, L., Hong, G., Ma, J., Voelker, K., Barrentine, H., Aronson, R., Henderson, M., Lamberti, J., Krawiecki, C., Case, A., Wilkins, L., Ayers, J.M., Fangmann, K., Landis, J., DeSouza, L., Hammoud, Z., Kah, D., Sanchez, J., Murdoch, L., Silvestri, Gerard A., Tanner, Nichole T., Kearney, Paul, Vachani, Anil, Massion, Pierre P., Porter, Alexander, Springmeyer, Steven C., Fang, Kenneth C., Midthun, David, and Mazzone, Peter J.
Published: 2018
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16. Evidence-based policy and practice: Meaningful differences in maternal smoking behaviour during pregnancy: implications for infant behavioural vulnerability

Author: Pickett, K E, Wood, C, Adamson, J, DeSouza, L, D'Souza, L, and Wakschlag, L S
Published: 2008

17. Leucine amino peptidase a better indicator of carcinoma of liver, biliary tract and pancreas

Author: Ghadge M. S., Sirsat A. V., Bhansali M. S., Desouza L. J., and Jagannath P
Published: 2001
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18. Thyroid Hormone Accelerates the Differentiation of Adult Hippocampal Progenitors

Author: Kapoor, R., Desouza, L. A., Nanavaty, I. N., Kernie, S. G., and Vaidya, V. A.
Published: 2012
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19. THYROID HORMONE REGULATION OF SONIC HEDGEHOG EXPRESSION IN THE DEVELOPING AND ADULT BRAIN: RELEVANCE TO NEUROGENESIS AND OLIGODENDROGENESIS

Author: Desouza, L., Sathanoori, M., Tole, S., and Vaidya, V.
Published: 2010

20. Modified method for determination of serum beta-glucuronidase: A comparative study using P-nitrophenyl glucuronide and phenolphthalein glucuronide as substrate in gastrointestinal tract carcinomas

Author: Khanolkar, M. M., Sirsat, A. V., Walvekar, S. S., Bhansali, M. S., and Desouza, L. J.
Published: 1997
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21. Meaningful differences in maternal smoking behaviour during pregnancy: implications for infant behavioural vulnerability

Author: Pickett, K E, Wood, C, Adamson, J, DeSouza, L, and Wakschlag, L S
Published: 2008
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22. Studies on serum amylases in carcinoma of liver, biliary tract and pancreas

Author: Khanolkar M. M., Sirsat A. V., Bhansali M. S., Jagannath P., and Desouza L. J.
Published: 1996
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23. A new layout optimization technique for interferometric arrays and the final MWA antenna layout

Author: Haystack Observatory, MIT Kavli Institute for Astrophysics and Space Research, Beardsley, A. P., Hazelton, B. J., Morales, M. F., Capallo, R.J., Goeke, Robert F, Emrich, D., Lonsdale, Colin John, Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Bunton, J. D., Corey, Brian E, Deshpande, A., deSouza, L., Gaensler, B. M., Greenhill, L. J., Herne, D., Hewitt, Jacqueline N, Kaplan, D. L., Kasper, J. C., Kincaid, Barton B., Koenig, R., Kratzenberg, Eric W, Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morgan, Edward H, Oberoi, Divya, Ord, S. M., Pathikulangara, J., Prabu, T., Rogers, Alan E E, Roshi, A., Salah, Joseph E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, Alan R, Williams, A., Williams, C. L., Wyithe, J. S. B., Remillard, Ronald A, Haystack Observatory, MIT Kavli Institute for Astrophysics and Space Research, Beardsley, A. P., Hazelton, B. J., Morales, M. F., Capallo, R.J., Goeke, Robert F, Emrich, D., Lonsdale, Colin John, Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Bunton, J. D., Corey, Brian E, Deshpande, A., deSouza, L., Gaensler, B. M., Greenhill, L. J., Herne, D., Hewitt, Jacqueline N, Kaplan, D. L., Kasper, J. C., Kincaid, Barton B., Koenig, R., Kratzenberg, Eric W, Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morgan, Edward H, Oberoi, Divya, Ord, S. M., Pathikulangara, J., Prabu, T., Rogers, Alan E E, Roshi, A., Salah, Joseph E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, Alan R, Williams, A., Williams, C. L., Wyithe, J. S. B., and Remillard, Ronald A
Abstract: Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed - even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution and snapshot PSF for this array choice., U.S. National Science Foundation (grants AST CAREER-0847753, AST-0457585, AST-0908884 and PHY-0835713), Australian Research Council (grants LE0775621 and LE0882938), U.S. Air Force Office of Scientific Research (grant FA9550-0510247)
Published: 2020

24. Immunohistochemistry of the canine vomeronasal organ

Author: Dennis, J. C., Allgier, J. G., Desouza, L. S., Eward, W. C., and Morrison, E. E.
Published: 2003

25. 'I can do this': a qualitative exploration of acceptability and experiences of a physical activity behaviour change intervention in people with multiple sclerosis in the UK

Author: Norris, M, Fortune, J, Ryan, J, Stennett, A, Kilbride, C, Lavelle, G, Desouza, L, Abdul, M, Brewin, D, Anokye, N, and Victor, C
Abstract: Objectives: The purpose of this study was to explore experiences of people with multiple sclerosis (MS) who participated in iStep-MS, a feasibility randomized controlled trial of a behaviour-change intervention that aimed to increase physical activity and reduce sedentary behaviour. Design: A qualitative approach was undertaken embedded in the feasibility randomised controlled trial. One-to-one semi-structured interviews were conducted and analysed using Framework analysis. Setting: Participants were recruited from a single MS therapy centre in the southeast of England, UK. Participants: Sixty people with MS were randomly allocated in a 1:1 ratio to the intervention or usual care. Following a purposive sampling strategy, 15 participants from the intervention arm undertook 1:1 semi-structured interviews. Interventions: The iStep-MS intervention consisted of four therapist-led sessions over 12 weeks, supported by a handbook and pedometer. Results: Three themes were identified from the data. “I can do this”: Developing competence in physical activity (PA) highlights the enhanced physical activity confidence gained through goal setting and accomplishment. I felt valued”: the nurturing culture provides an overview of the supportive and non-judgemental environment created by the programme structure and therapeutic relationship. Finally, “What can I do?”: empowered enactment describes the transition from the supported iStep-MS intervention to intrinsically motivated physical activity enactment. Conclusions:Overall, this study supports the acceptability of the iStep-MS intervention and identified key areas that supported participants to be physically active. Changing physical activity behaviour in people with MS through increasing steps: iSTEP-MS
Published: 2019

26. The meaning of exercise and physical activity in community dwelling people with multiple sclerosis

Author: Stennett, A, Norris, M, and Desouza, L
Subjects: priorities, coping, qualitative, physical activity, multiple sclerosis
Abstract: Copyright © 2018 The Author(s). Purpose This study explored the meanings community dwelling people with Multiple Sclerosis ascribe to exercise and physical activity. Method Using a qualitative approach, 16 face-to-face, semi-structured interviews were conducted. Data were analysed using Framework Analysis and emerging themes developed. Results Five themes were identified: “A Type of Movement”, “The Impact of Exercise and Physical Activity”, “It Changes”, “Sense of Loss” and “Coping with Multiple Sclerosis”. The findings demonstrated that people with multiple sclerosis held a multidimensional and complex view about exercise and physical activity. Conclusion The meanings people with multiple sclerosis ascribe to exercise and physical activity extended beyond movement, reflecting how they lived with a variable neurological condition. Personal and contextual factors were dominant influences.
Published: 2018

27. Correlates of objectively measured physical activity in persons with multiple sclerosis

Author: Fortune, J., primary, Norris, M., additional, Stennett, A.M., additional, Kilbride, C., additional, Lavelle, G., additional, Hendrie, W., additional, DeSouza, L., additional, Victor, C., additional, Abdul, M., additional, Ayokye, N., additional, and Ryan, J.M., additional
Published: 2019
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28. Validity of the international physical activity questionnaire (IPAQ-s) as a measure of physical activity in people with multiple sclerosis

Author: Fortune, J., primary, Norris, M., additional, Stennett, A.M., additional, Kilbride, C., additional, Lavelle, G., additional, Hendrie, W., additional, DeSouza, L., additional, Victor, C., additional, Abdul, M., additional, Ayokye, N., additional, and Ryan, J.M., additional
Published: 2019
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29. Changing physical activity behaviour for people with multiple sclerosis: protocol of a randomised controlled feasibility trial (iStep-MS)

Author: Ryan, J, Fortune, J, Stennett, A, Kilbride, C, Anokye, N, Victor, C, Hendrie, W, Abdul, M, deSouza, L, Lavelle, G, Brewin, D, David, L, and Norris, M
Subjects: Multiple Sclerosis, public health, rehabilitation medicine, Self Efficacy, Exercise Therapy, Neurology, Research Design, London, Outcome Assessment, Health Care, Protocol, Quality of Life, Humans, Sedentary Behavior, Exercise, Fatigue
Abstract: Copyright © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. Introduction: Although physical activity may reduce disease burden, fatigue and disability, and improve quality of life among people with multiple sclerosis (MS) many people with MS are physically inactive and spend significant time in sedentary behaviour. Behaviour-change interventions may assist people with MS to increase physical activity and reduce sedentary behaviour. However, few studies have investigated their effectiveness using objective measures of physical activity, particularly in the long-term. Further, interventions that have proven effective in the short-term may not be feasible in clinical practice because of the large amount of support provided. The iStep-MS trial aims to determine the safety, feasibility and acceptability of a behaviour-change intervention to increase physical activity and reduce sedentary behaviour among people with MS. Methods and analysis: Sixty people with MS will be randomised (1:1 ratio) to receive a 12-week intervention or usual care only. The intervention consists of four physical activity consultations with a physiotherapist supported by a handbook and pedometer. Outcomes assessed at baseline, 12 weeks and 9 months are physical activity (Actigraph GT3x-BT accelerometer), sedentary behaviour (activPAL3µ), self-reported activity and sitting time, walking capability, fatigue, self-efficacy, participation, quality of life, health service use. The safety of the intervention will be determined by assessing change in pain and fatigue and the incidence of adverse events during the follow-up period. A parallel process evaluation will assess the feasibility and acceptability of the intervention through assessment of fidelity to the programme and semi-structured interviews exploring participants’ and therapists’ experiences of the intervention. The feasibility of conducting an economic evaluation will be determined by collecting data on quality of life and resource use. Ethics and dissemination: Research Ethics Committee approval has been granted from Brunel University London. Results of the trial will be submitted for publication in journals, and distributed to people with MS and physiotherapists. This study is funded by a project grant from the MS Society, UK (award reference: 53).
Published: 2017

30. Fluid management with a simplified conservative protocol for the acute respiratory distress syndrome

Author: Grissom, CK, Hirshberg, EL, Dickerson, JB, Brown, SM, Lanspa, MJ, Liu, KD, Schoenfeld, D, Tidswell, M, Hite, RD, Rock, P, Miller, RR, Morris, AH, Hudson, L, Gundel, S, Hough, C, Neff, M, Sims, K, Ungar, A, Watkins, T, Steingrub, J, Braden, E, DeSouza, L, Germain, J, Kardos, C, Kelley, D, Kozikowski, L, Ouellette, S, Guntupalli, K, Bandi, V, Pope, C, Ross, C, Brower, R, Fessler, H, Hager, D, Mendez-Tellez, P, Needham, D, Oakjones, K, Sevransky, J, Workneh, A, Shanholtz, C, Herr, D, Howes, H, Netzer, G, Sampaio, A, Titus, J, Sloane, P, Beck, T, Highfield, H, King, S, Lee, B, Bolouri, N, Wiedemann, HP, Ashton, RW, Culver, DA, Frederick, T, Guzman, JA, Komara, JJ, Reddy, AJ, Hejal, R, Andrews, M, Haney, D, Connors, AF, Lasalvia, S, Thornton, JD, Warren, EL, Moss, M, Burnham, EL, Gray, L, Maloney, J, Mealer, M, Douglas, I, Overdier, K, Thompson, K, Wolken, R, Frankel, S, McKeehan, J, Warner, ML, Bost, T, Higgins, C, Hodgin, K, MacIntyre, N, Brown, L, Cox, C, Gentile, M, Govert, J, Knudsen, N, Carson, S, Chang, L, and Choudhury, S
Abstract: © 2015 by the Society of Critical Care Medicine and Lippincott Williams & Wilkins. Objectives: In the Fluid and Catheter Treatment Trial (FACTT) of the National Institutes of Health Acute Respiratory Distress Syndrome Network, a conservative fluid protocol (FACTT Conservative) resulted in a lower cumulative fluid balance and better outcomes than a liberal fluid protocol (FACTT Liberal). Subsequent Acute Respiratory Distress Syndrome Network studies used a simplified conservative fluid protocol (FACTT Lite). The objective of this study was to compare the performance of FACTT Lite, FACTT Conservative, and FACTT Liberal protocols.
Published: 2015
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31. The Big Physio Survey (BPS)

Author: Green, A., primary, DeSouza, L., additional, Lowe, R., additional, and Walton, A., additional
Published: 2016
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32. Solitary rectal ulcer syndrome: Twenty cases seen at an oncology center

Author: Britto, Errol, Borges, Anita M., Swaroop, V. Santhi, Jagannath, P., and DeSouza, L. J.
Published: 1987
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33. A new layout optimization technique for interferometric arrays, applied to the Murchison Widefield Array

Author: Beardsley, A. P., Hazelton, B. J., Morales, M. F., Capallo, R.J., Goeke, Robert F, Emrich, D., Lonsdale, Colin John, Arcus, W., Barnes, D., Bernardi, G., Bowman, J. D., Bunton, J. D., Corey, Brian E, Deshpande, A., deSouza, L., Gaensler, B. M., Greenhill, L. J., Herne, D., Hewitt, Jacqueline N, Kaplan, D. L., Kasper, J. C., Kincaid, Barton B., Koenig, R., Kratzenberg, Eric W, Lynch, M. J., McWhirter, S. R., Mitchell, D. A., Morgan, Edward H, Oberoi, Divya, Ord, S. M., Pathikulangara, J., Prabu, T., Rogers, Alan E E, Roshi, A., Salah, Joseph E., Sault, R. J., Shankar, N. Udaya, Srivani, K. S., Stevens, J., Subrahmanyan, R., Tingay, S. J., Wayth, R. B., Waterson, M., Webster, R. L., Whitney, Alan R, Williams, A., Williams, C. L., Wyithe, J. S. B., Remillard, Ronald A, Haystack Observatory, and MIT Kavli Institute for Astrophysics and Space Research
Abstract: Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed - even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution and snapshot PSF for this array choice., U.S. National Science Foundation (grants AST CAREER-0847753, AST-0457585, AST-0908884 and PHY-0835713), Australian Research Council (grants LE0775621 and LE0882938), U.S. Air Force Office of Scientific Research (grant FA9550-0510247)
Published: 2012

34. A digital-receiver for the Murchison Widefield Array

Author: Prabu, T, Srivani, KS, Roshi, DA, Kamini, PA, Madhavi, S, Emrich, D, Crosse, B, Williams, AJ, Waterson, M, Deshpande, AA, Shankar, NU, Subrahmanyan, R, Briggs, FH, Goeke, RF, Tingay, SJ, Johnston-Hollitt, M, Gopalakrishna, MR, Morgan, EH, Pathikulangara, J, Bunton, JD, Hampson, G, Williams, C, Ord, SM, Wayth, RB, Kumar, D, Morales, MF, deSouza, L, Kratzenberg, E, Pallot, D, McWhirter, R, Hazelton, BJ, Arcus, W, Barnes, DG, Bernardi, G, Booler, T, Bowman, JD, Cappallo, RJ, Corey, BE, Greenhill, LJ, Herne, D, Hewitt, JN, Kaplan, DL, Kasper, JC, Kincaid, BB, Koenig, R, Lonsdale, CJ, Lynch, MJ, Mitchell, DA, Oberoi, D, Remillard, RA, Rogers, AE, Salah, JE, Sault, RJ, Stevens, JB, Tremblay, S, Webster, RL, Whitney, AR, Wyithe, SB, Prabu, T, Srivani, KS, Roshi, DA, Kamini, PA, Madhavi, S, Emrich, D, Crosse, B, Williams, AJ, Waterson, M, Deshpande, AA, Shankar, NU, Subrahmanyan, R, Briggs, FH, Goeke, RF, Tingay, SJ, Johnston-Hollitt, M, Gopalakrishna, MR, Morgan, EH, Pathikulangara, J, Bunton, JD, Hampson, G, Williams, C, Ord, SM, Wayth, RB, Kumar, D, Morales, MF, deSouza, L, Kratzenberg, E, Pallot, D, McWhirter, R, Hazelton, BJ, Arcus, W, Barnes, DG, Bernardi, G, Booler, T, Bowman, JD, Cappallo, RJ, Corey, BE, Greenhill, LJ, Herne, D, Hewitt, JN, Kaplan, DL, Kasper, JC, Kincaid, BB, Koenig, R, Lonsdale, CJ, Lynch, MJ, Mitchell, DA, Oberoi, D, Remillard, RA, Rogers, AE, Salah, JE, Sault, RJ, Stevens, JB, Tremblay, S, Webster, RL, Whitney, AR, and Wyithe, SB
Published: 2015

35. The Murchison Widefield Array Correlator

Author: Ord, SM, Crosse, B, Emrich, D, Pallot, D, Wayth, RB, Clark, MA, Tremblay, SE, Arcus, W, Barnes, D, Bell, M, Bernardi, G, Bhat, NDR, Bowman, JD, Briggs, F, Bunton, JD, Cappallo, RJ, Corey, BE, Deshpande, AA, deSouza, L, Ewell-Wice, A, Feng, L, Goeke, R, Greenhill, LJ, Hazelton, BJ, Herne, D, Hewitt, JN, Hindson, L, Hurley-Walker, N, Jacobs, D, Johnston-Hollitt, M, Kaplan, DL, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Kudryavtseva, N, Lenc, E, Lonsdale, CJ, Lynch, MJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Offringa, A, Pathikulangara, J, Pindor, B, Prabu, T, Procopio, P, Remillard, RA, Riding, J, Rogers, AEE, Roshi, A, Salah, JE, Sault, RJ, Shankar, NU, Srivani, KS, Stevens, J, Subrahmanyan, R, Tingay, SJ, Waterson, M, Webster, RL, Whitney, AR, Williams, A, Williams, CL, Wyithe, JSB, Ord, SM, Crosse, B, Emrich, D, Pallot, D, Wayth, RB, Clark, MA, Tremblay, SE, Arcus, W, Barnes, D, Bell, M, Bernardi, G, Bhat, NDR, Bowman, JD, Briggs, F, Bunton, JD, Cappallo, RJ, Corey, BE, Deshpande, AA, deSouza, L, Ewell-Wice, A, Feng, L, Goeke, R, Greenhill, LJ, Hazelton, BJ, Herne, D, Hewitt, JN, Hindson, L, Hurley-Walker, N, Jacobs, D, Johnston-Hollitt, M, Kaplan, DL, Kasper, JC, Kincaid, BB, Koenig, R, Kratzenberg, E, Kudryavtseva, N, Lenc, E, Lonsdale, CJ, Lynch, MJ, McKinley, B, McWhirter, SR, Mitchell, DA, Morales, MF, Morgan, E, Oberoi, D, Offringa, A, Pathikulangara, J, Pindor, B, Prabu, T, Procopio, P, Remillard, RA, Riding, J, Rogers, AEE, Roshi, A, Salah, JE, Sault, RJ, Shankar, NU, Srivani, KS, Stevens, J, Subrahmanyan, R, Tingay, SJ, Waterson, M, Webster, RL, Whitney, AR, Williams, A, Williams, CL, and Wyithe, JSB
Abstract: The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
Published: 2015

36. The Murchison Widefield Array Correlator

Author: Ord, Stephen, Crosse, B., Emrich, D., Pallot, D., Wayth, Randall, Clark, M., Tremblay, S., Arcus, W., Barnes, D., Bell, M., Bernardi, G., Bhat, N., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Ewell-Wice, A., Feng, L., Goeke, R., Greenhill, L., Hazelton, B., Herne, D., Hewitt, J., Hindson, L., Hurley-Walker, N., Jacobs, D., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Kudryavtseva, N., Lenc, E., Lonsdale, C., Lynch, Mervyn, McKinley, B., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Offringa, A., Pathikulangara, J., Pindor, B., Prabu, T., Procopio, P., Remillard, R., Riding, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, M., Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Ord, Stephen, Crosse, B., Emrich, D., Pallot, D., Wayth, Randall, Clark, M., Tremblay, S., Arcus, W., Barnes, D., Bell, M., Bernardi, G., Bhat, N., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Ewell-Wice, A., Feng, L., Goeke, R., Greenhill, L., Hazelton, B., Herne, D., Hewitt, J., Hindson, L., Hurley-Walker, N., Jacobs, D., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Kudryavtseva, N., Lenc, E., Lonsdale, C., Lynch, Mervyn, McKinley, B., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Offringa, A., Pathikulangara, J., Pindor, B., Prabu, T., Procopio, P., Remillard, R., Riding, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, M., Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.
Abstract: The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
Published: 2015

37. A digital-receiver for the Murchison Widefield Array

Author: Prabu, T., Srivani, K., Roshi, D., Kamini, P., Madhavi, S., Emrich, D., Crosse, B., Williams, A., Waterson, M., Deshpande, A., Shankar, N., Subrahmanyan, R., Briggs, F., Goeke, R., Tingay, Steven, Johnston-Hollitt, M., R, G., Morgan, E., Pathikulangara, J., Bunton, J., Hampson, G., Williams, C., Ord, Stephen, Wayth, Randall, Kumar, D., Morales, M., DeSouza, L., Kratzenberg, E., Pallot, D., McWhirter, R., Hazelton, B., Arcus, W., Barnes, D., Bernardi, G., Booler, T., Bowman, J., Cappallo, R., Corey, B., Greenhill, L., Herne, D., Hewitt, J., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Lonsdale, C., Lynch, Mervyn, Mitchell, D., Oberoi, D., Remillard, R., Rogers, A., Salah, J., Sault, R., Stevens, J., Tremblay, S., Webster, R., Whitney, A., Wyithe, S., Prabu, T., Srivani, K., Roshi, D., Kamini, P., Madhavi, S., Emrich, D., Crosse, B., Williams, A., Waterson, M., Deshpande, A., Shankar, N., Subrahmanyan, R., Briggs, F., Goeke, R., Tingay, Steven, Johnston-Hollitt, M., R, G., Morgan, E., Pathikulangara, J., Bunton, J., Hampson, G., Williams, C., Ord, Stephen, Wayth, Randall, Kumar, D., Morales, M., DeSouza, L., Kratzenberg, E., Pallot, D., McWhirter, R., Hazelton, B., Arcus, W., Barnes, D., Bernardi, G., Booler, T., Bowman, J., Cappallo, R., Corey, B., Greenhill, L., Herne, D., Hewitt, J., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Lonsdale, C., Lynch, Mervyn, Mitchell, D., Oberoi, D., Remillard, R., Rogers, A., Salah, J., Sault, R., Stevens, J., Tremblay, S., Webster, R., Whitney, A., and Wyithe, S.
Abstract: An FPGA-based digital-receiver has been developed for a low-frequency imaging radio interferometer, the Murchison Widefield Array (MWA). The MWA, located at the Murchison Radio-astronomy Observatory (MRO) in Western Australia, consists of 128 dual-polarized aperture-array elements (tiles) operating between 80 and 300 MHz, with a total processed bandwidth of 30.72 MHz for each polarization. Radio-frequency signals from the tiles are amplified and band limited using analog signal conditioning units; sampled and channelized by digital-receivers. The signals from eight tiles are processed by a single digital-receiver, thus requiring 16 digital-receivers for the MWA. The main function of the digital-receivers is to digitize the broad-band signals from each tile, channelize them to form the sky-band, and transport it through optical fibers to a centrally located correlator for further processing. The digital-receiver firmware also implements functions to measure the signal power, perform power equalization across the band, detect interference-like events, and invoke diagnostic modes. The digital-receiver is controlled by high-level programs running on a single-board-computer. This paper presents the digital-receiver design, implementation, current status, and plans for future enhancements.
Published: 2015

38. The Murchison Widefield Array Correlator

Author: Ord, S. M., primary, Crosse, B., additional, Emrich, D., additional, Pallot, D., additional, Wayth, R. B., additional, Clark, M. A., additional, Tremblay, S. E., additional, Arcus, W., additional, Barnes, D., additional, Bell, M., additional, Bernardi, G., additional, Bhat, N. D. R., additional, Bowman, J. D., additional, Briggs, F., additional, Bunton, J. D., additional, Cappallo, R. J., additional, Corey, B. E., additional, Deshpande, A. A., additional, deSouza, L., additional, Ewell-Wice, A., additional, Feng, L., additional, Goeke, R., additional, Greenhill, L. J., additional, Hazelton, B. J., additional, Herne, D., additional, Hewitt, J. N., additional, Hindson, L., additional, Hurley-Walker, N., additional, Jacobs, D., additional, Johnston-Hollitt, M., additional, Kaplan, D. L., additional, Kasper, J. C., additional, Kincaid, B. B., additional, Koenig, R., additional, Kratzenberg, E., additional, Kudryavtseva, N., additional, Lenc, E., additional, Lonsdale, C. J., additional, Lynch, M. J., additional, McKinley, B., additional, McWhirter, S. R., additional, Mitchell, D. A., additional, Morales, M. F., additional, Morgan, E., additional, Oberoi, D., additional, Offringa, A., additional, Pathikulangara, J., additional, Pindor, B., additional, Prabu, T., additional, Procopio, P., additional, Remillard, R. A., additional, Riding, J., additional, Rogers, A. E. E., additional, Roshi, A., additional, Salah, J. E., additional, Sault, R. J., additional, Udaya Shankar, N., additional, Srivani, K. S., additional, Stevens, J., additional, Subrahmanyan, R., additional, Tingay, S. J., additional, Waterson, M., additional, Webster, R. L., additional, Whitney, A. R., additional, Williams, A., additional, Williams, C. L., additional, and Wyithe, J. S. B., additional
Published: 2015
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39. A 189 MHz, 2400 deg2 polarization survey with the Murchison widefield array 32-element prototype

Author: Bernardi, G ., Greenhill, L., Mitchell, D., Ord, S., Hazelton, B., Gaensler, B., de Oliveira-Costa, A., Morales, M., Udaya Shankar, N., Subrahmanyan, R., Wayth, Randall, Lenc, E., Williams, C., Arcus, Wayne, Arora, B., Barnes, D., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Herne, D., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Srivani, K., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, A., Wyithe, J., Bernardi, G ., Greenhill, L., Mitchell, D., Ord, S., Hazelton, B., Gaensler, B., de Oliveira-Costa, A., Morales, M., Udaya Shankar, N., Subrahmanyan, R., Wayth, Randall, Lenc, E., Williams, C., Arcus, Wayne, Arora, B., Barnes, D., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Herne, D., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Srivani, K., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, A., and Wyithe, J.
Abstract: We present a Stokes I, Q and U survey at 189 MHz with the Murchison Widefield Array 32 element prototype covering 2400 deg2. The survey has a 15.6 arcmin angular resolution and achieves a noise level of 15 mJy beam–1. We demonstrate a novel interferometric data analysis that involves calibration of drift scan data, integration through the co-addition of warped snapshot images, and deconvolution of the point-spread function through forward modeling. We present a point source catalog down to a flux limit of 4 Jy. We detect polarization from only one of the sources, PMN J0351-2744, at a level of 1.8% ± 0.4%, whereas the remaining sources have a polarization fraction below 2%. Compared to a reported average value of 7% at 1.4 GHz, the polarization fraction of compact sources significantly decreases at low frequencies. We find a wealth of diffuse polarized emission across a large area of the survey with a maximum peak of ~13 K, primarily with positive rotation measure values smaller than +10 rad m–2. The small values observed indicate that the emission is likely to have a local origin (closer than a few hundred parsecs). There is a large sky area at α >= 2h30m where the diffuse polarized emission rms is fainter than 1 K. Within this area of low Galactic polarization we characterize the foreground properties in a cold sky patch at (α, δ) = (4h, –27°.6) in terms of three-dimensional power spectra.
Published: 2013

40. The Murchison Widefield Array: The Square Kilometre Array Precursor at Low Radio Frequencies

Author: Tingay, Steven, Emrich, David, Ord, Stephen, Booler, Tom, Crosse, Brian, Wayth, Randall, Tremblay, Steven, Pallot, Dave, Colegate, Timothy, Kudryavtseva, Nadia, Goeke, R., Bowman, J., Mitchell, D., Morales, M., Lonsdale, C., Colegate, T., Wicenec, A., Arcus, W., Barnes, D., Bernardi, G., Briggs, F., Burns, S., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., Desouza, L., Gaensler, B., Greenhill, L., Hall, P., Hazelton, B., Herne, D., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lynch, M., McKinley, B., McWhirter, S., Morgan, E., Oberoi, D, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya-Shankar, N., Schlagenhaufer, F., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, M., Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Tingay, Steven, Emrich, David, Ord, Stephen, Booler, Tom, Crosse, Brian, Wayth, Randall, Tremblay, Steven, Pallot, Dave, Colegate, Timothy, Kudryavtseva, Nadia, Goeke, R., Bowman, J., Mitchell, D., Morales, M., Lonsdale, C., Colegate, T., Wicenec, A., Arcus, W., Barnes, D., Bernardi, G., Briggs, F., Burns, S., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., Desouza, L., Gaensler, B., Greenhill, L., Hall, P., Hazelton, B., Herne, D., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lynch, M., McKinley, B., McWhirter, S., Morgan, E., Oberoi, D, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya-Shankar, N., Schlagenhaufer, F., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, M., Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.
Abstract: The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
Published: 2013

41. The EoR sensitivity of the Murchison Widefield Array

Author: Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Tingay, Steven, Wayth, Randall, Waterson, Mark, Beardsley, A., Hazelton, B., Morales, M., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Gaensler, B., Goeke, R., Greenhill, L., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Tingay, Steven, Wayth, Randall, Waterson, Mark, Beardsley, A., Hazelton, B., Morales, M., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Gaensler, B., Goeke, R., Greenhill, L., Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.
Abstract: Using the final 128 antenna locations of the Murchison Widefield Array (MWA), we calculate its sensitivity to the epoch of reionization (EoR) power spectrum of redshifted 21 cm emission for a fiducial model and provide the tools to calculate the sensitivity for any model. Our calculation takes into account synthesis rotation, chromatic and asymmetrical baseline effects, and excludes modes that will be contaminated by foreground subtraction. For the fiducial model, the MWA will be capable of a 14s detection of the EoR signal with one full season of observation on two fields (900 and 700 h).
Published: 2013

42. On the detection and tracking of space debris using the Murchison Wdefield Array. I. Simulations and test observations demonstrate feasibility

Author: Tingay, Steven, Kaplan, D.L., McKinley, B., Briggs, F., Wayth, Randall, Hurley-Walker, N., Kennewell, J., Smith, C., Zhang, K., Arcus, W., Bhat, Ramesh, Emrich D., Herne, D., Kudryavtseva, N., Lynch, M., Ord, S.M., Waterson, M., Barnes, D.G., Bell, M., Gaensler, B.M., Lenc, E., Bernardi, G., Greenhill, L.J., Kasper, J.C., Bowman, J.D., Jacobs, D., Bunton, J.D., Desouza, L., Koenig, R., Pathikulangara, J., Stevens, J., Cappallo, R.J., Corey, B.E., Kincaid, B.B., Kratzenberg, E., Lonsdale, C.J., McWhirter, S.R., Rogers, A.E.E., Salah, J.E., Whitney, A.R., Deshpande, A., Prabu, T., Udaya Shankar, N., Srivani, K.S., Subrahmanyan, R., Ewall-Wice, A., Feng, L., Goeke, R., Morgan, E., Remillard, R.A., Williams, C.L., Hazelton, B.J., Morales, M.F., Johnston-Hollitt, M., Mitchell, D.A., Procopio, P., Riding, J., Webster, R.L., Wyithe, J.S.B., Oberoi, D., Roshi, A., Sault, R.J., Williams, A., Tingay, Steven, Kaplan, D.L., McKinley, B., Briggs, F., Wayth, Randall, Hurley-Walker, N., Kennewell, J., Smith, C., Zhang, K., Arcus, W., Bhat, Ramesh, Emrich D., Herne, D., Kudryavtseva, N., Lynch, M., Ord, S.M., Waterson, M., Barnes, D.G., Bell, M., Gaensler, B.M., Lenc, E., Bernardi, G., Greenhill, L.J., Kasper, J.C., Bowman, J.D., Jacobs, D., Bunton, J.D., Desouza, L., Koenig, R., Pathikulangara, J., Stevens, J., Cappallo, R.J., Corey, B.E., Kincaid, B.B., Kratzenberg, E., Lonsdale, C.J., McWhirter, S.R., Rogers, A.E.E., Salah, J.E., Whitney, A.R., Deshpande, A., Prabu, T., Udaya Shankar, N., Srivani, K.S., Subrahmanyan, R., Ewall-Wice, A., Feng, L., Goeke, R., Morgan, E., Remillard, R.A., Williams, C.L., Hazelton, B.J., Morales, M.F., Johnston-Hollitt, M., Mitchell, D.A., Procopio, P., Riding, J., Webster, R.L., Wyithe, J.S.B., Oberoi, D., Roshi, A., Sault, R.J., and Williams, A.
Abstract: The Murchison Widefield Array (MWA) is a new low-frequency interferometric radio telescope, operating in the benign radio frequency environment of remote Western Australia. The MWA is the low-frequency precursor to the Square Kilometre Array (SKA) and is the first of three SKA precursors to be operational, supporting a varied science mission ranging from the attempted detection of the Epoch of Reionization to the monitoring of solar flares and space weather. In this paper we explore the possibility that the MWA can be used for the purposes of Space Situational Awareness (SSA). In particular we propose that the MWA can be used as an element of a passive radar facility operating in the frequency range 87.5-108 MHz (the commercial FM broadcast band). In this scenario the MWA can be considered the receiving element in a bi-static radar configuration, with FM broadcast stations serving as non-cooperative transmitters. The FM broadcasts propagate into space, are reflected off debris in Earth orbit, and are received at the MWA. The imaging capabilities of the MWA can be used to simultaneously detect multiple pieces of space debris, image their positions on the sky as a function of time, and provide tracking data that can be used to determine orbital parameters. Such a capability would be a valuable addition to Australian and global SSA assets, in terms of southern and eastern hemispheric coverage. We provide a feasibility assessment of this proposal, based on simple calculations and electromagnetic simulations, that shows that the detection of sub-meter size debris should be possible (debris radius of >0.5 m to ∼1000 km altitude). We also present a proof-of-concept set of observations that demonstrate the feasibility of the proposal, based on the detection and tracking of the International Space Station via reflected FM broadcast signals originating in southwest Western Australia. These observations broadly validate our calculations and simulations. We discuss some signifi
Published: 2013

43. The giant lobes of Centaurus A observed at 118MHz with the Murchison Widefield Array

Author: McKinley, B., Briggs, F., Gaensler, B., Feain, I., Bernardi, G., Wayth, Randall, Johnston-Hollitt, M., Offringa, A., Arcus, Wayne, Barnes, D., Bowman, J., Bunton, J., Capallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kaplan, David, Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, D., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, Andrew, Williams, C., Wyithe, J., McKinley, B., Briggs, F., Gaensler, B., Feain, I., Bernardi, G., Wayth, Randall, Johnston-Hollitt, M., Offringa, A., Arcus, Wayne, Barnes, D., Bowman, J., Bunton, J., Capallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kaplan, David, Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, D., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Waterson, Mark, Webster, R., Whitney, A., Williams, Andrew, Williams, C., and Wyithe, J.
Abstract: We present new wide-field observations of Centaurus A (Cen A) and the surrounding region at 118MHz with the Murchison Widefield Array (MWA) 32-tile prototype, with which we investigate the spectral-index distribution of Cen A’s giant radio lobes. We compare our images to 1.4 GHz maps of Cen A and compute spectral indices using temperature–temperature plots and spectral tomography. We find that the morphologies at 118MHz and 1.4 GHz match very closely apart from an extra peak in the southern lobe at 118 MHz, which provides tentative evidence for the existence of a southern counterpart to the northern middle lobe of Cen A. Our spatially averaged spectral indices for both the northern and southern lobes are consistent with previous analyses, however we find significant spatial variation of the spectra across the extent of each lobe. Both the spectral-index distribution and the morphology at low radio frequencies support a scenario of multiple outbursts of activity from the central engine. Our results are consistent with inverse-Compton modelling of radio and gamma-ray data that support a value for the lobe age of between 10 and 80 Myr.
Published: 2013

44. A survey for transients and variables with the Murchison Widefield Array 32-tile prototype at 154 MHz

Author: Trott, Cathryn, Hurley-Walker, Natasha, Wayth, Randall, Macquart, Jean-Pierre, Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Waterson, Mark, Williams, Andrew, Bell, M., Murphy, T., Kaplan, D., Hancock, P., Gaensler, B., Banyer, J., Bannister, K., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Johnston-Hollitt, M., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, C., Wyithe, J., Trott, Cathryn, Hurley-Walker, Natasha, Wayth, Randall, Macquart, Jean-Pierre, Arcus, Wayne, Emrich, David, Herne, David, Lynch, Mervyn, Ord, Stephen, Tingay, Steven, Waterson, Mark, Williams, Andrew, Bell, M., Murphy, T., Kaplan, D., Hancock, P., Gaensler, B., Banyer, J., Bannister, K., Barnes, D., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Goeke, R., Greenhill, L., Hazelton, B., Hewitt, J., Johnston-Hollitt, M., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Sault, R., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Webster, R., Whitney, A., Williams, C., and Wyithe, J.
Abstract: We present a search for transient and variable radio sources at 154 MHz with the Murchison Widefield Array 32-tile prototype. Fifty-one images were obtained that cover a field of view of 1430 deg2 centred on Hydra A. The observations were obtained over three days in 2010 March and three days in 2011 April and May. The mean cadence of the observations was 26 minutes and there was additional temporal information on day and year timescales. We explore the variability of a sample of 105 low frequency radio sources within the field. Four bright (S > 6 Jy) candidate variable radio sources were identified that displayed low levels of short timescale variability (26 minutes). We conclude that this variability is likely caused by simplifications in the calibration strategy or ionospheric effects. On the timescale of one year we find two sources that show significant variability. We attribute this variability to either refractive scintillation or intrinsic variability. No radio transients were identified and we place an upper limit on the surface density of sources p < 7.5 × 10-5 deg-2 with flux densities > 5.5 Jy, and characteristic timescales of both 26 minutes and one year.
Published: 2013

45. The Murchison Widefield Array: solar science with the low frequency SKA Precursor

Author: Tingay, Steven, Oberoi, D., Cairns, I., Donea, A., Duffin, R., Arcus, Wayne, Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kennewell, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Udaya-Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, Mark, Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C., Wyithe, J., Tingay, Steven, Oberoi, D., Cairns, I., Donea, A., Duffin, R., Arcus, Wayne, Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., deSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kennewell, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morales, M., Morgan, E., Ord, S., Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Roshi, A., Salah, J., Udaya-Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Waterson, Mark, Wayth, Randall, Webster, R., Whitney, A., Williams, A., Williams, C., and Wyithe, J.
Abstract: The Murchison Widefield Array is a low frequency (80 – 300 MHz) SKA Precursor, comprising 128 aperture array elements (known as tiles) distributed over an area of 3 km diameter. The MWA is located at the extraordinarily radio quiet Murchison Radioastronomy Observatory in the mid-west of Western Australia, the selected home for the Phase 1 and Phase 2 SKA low frequency arrays. The MWA science goals include: 1) detection of fluctuations in the brightness temperature of the diffuse redshifted 21 cm line of neutral hydrogen from the epoch of reionisation; 2) studies of Galactic and extragalactic processes based on deep, confusion-limited surveys of the full sky visible to the array; 3) time domain astrophysics through exploration of the variable radio sky; and 4) solar imaging and characterisation of the heliosphere and ionosphere via propagation effects on background radio source emission. This paper concentrates on the capabilities of the MWA for solar science and summarises some of the solar science results to date, in advance of the initial operation of the final instrument in 2013.
Published: 2013

46. Fast Holographic Deconvolution: A New Technique for Precision Radio Interferometry

Author: Sullivan, I., Morales, M., Hazelton, B., Arcus, Wayne, Barnes, D., Bernardi, G., Briggs, F., Bowman, J., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., DeSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, R., Whitney, A., Sullivan, I., Morales, M., Hazelton, B., Arcus, Wayne, Barnes, D., Bernardi, G., Briggs, F., Bowman, J., Bunton, J., Cappallo, R., Corey, B., Deshpande, A., DeSouza, L., Emrich, David, Gaensler, B., Goeke, R., Greenhill, L., Herne, David, Hewitt, J., Johnston-Hollitt, M., Kaplan, D., Kasper, J., Kincaid, B., Koenig, R., Kratzenberg, E., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Mitchell, D., Morgan, E., Oberoi, D., Ord, Stephen, Pathikulangara, J., Prabu, T., Remillard, R., Rogers, A., Salah, J., Sault, R., Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, Mark, Webster, R., and Whitney, A.
Abstract: We introduce the Fast Holographic Deconvolution method for analyzing interferometric radio data. Our new method is an extension of A-projection/software-holography/forward modeling analysis techniques and shares their precision deconvolution and wide-field polarimetry, while being significantly faster than current implementations that use full direction-dependent antenna gains. Using data from the MWA 32 antenna prototype, we demonstrate the effectiveness and precision of our new algorithm. Fast Holographic Deconvolution may be particularly important for upcoming 21 cm cosmology observations of the Epoch of Reionization and Dark Energy where foreground subtraction is intimately related to the precision of the data reduction.
Published: 2012

47. A New Layout Optimization Technique for Interferometric Arrays, Applied to the Murchison Widefield Array

Author: Beardsley, A.P., Hazelton, B.J., Morales, M.F., Capallo, R.J., Goeke, R., Emrich, D., Lonsdale, C.J., Arcus, W., Barnes, D., Bernardi, G., Bowman, J.D., Bunton, J.D., Corey, B.E., Deshpande, A., DeSouza, L., Gaensler, B.M., Greenhill, L.J., Herne, D., Hewitt, J.N., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Koenig, R., Kratzenberg, E., Lynch, M.J., McWhirter, S.R., Mitchell, D.A., Morgan, E., Oberoi, D., Ord, S.M., Pathikulangara, J., Prabu, T., Remillard, R.A., Rogers, A.E.E., Roshi, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, M., Webster, R.L., Whitney, A.R., Williams, A., Wyithe, J.S.B., Beardsley, A.P., Hazelton, B.J., Morales, M.F., Capallo, R.J., Goeke, R., Emrich, D., Lonsdale, C.J., Arcus, W., Barnes, D., Bernardi, G., Bowman, J.D., Bunton, J.D., Corey, B.E., Deshpande, A., DeSouza, L., Gaensler, B.M., Greenhill, L.J., Herne, D., Hewitt, J.N., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Koenig, R., Kratzenberg, E., Lynch, M.J., McWhirter, S.R., Mitchell, D.A., Morgan, E., Oberoi, D., Ord, S.M., Pathikulangara, J., Prabu, T., Remillard, R.A., Rogers, A.E.E., Roshi, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Subrahmanyan, R., Tingay, Steven, Wayth, Randall, Waterson, M., Webster, R.L., Whitney, A.R., Williams, A., and Wyithe, J.S.B.
Abstract: Antenna layout is an important design consideration for radio interferometers because it determines the quality of the snapshot point spread function (PSF, or array beam). This is particularly true for experiments targeting the 21-cm Epoch of Reionization signal as the quality of the foreground subtraction depends directly on the spatial dynamic range and thus the smoothness of the baseline distribution. Nearly all sites have constraints on where antennas can be placed even at the remote Australian location of the Murchison Widefield Array (MWA) there are rock outcrops, flood zones, heritages areas, emergency runways and trees. These exclusion areas can introduce spatial structure into the baseline distribution that enhances the PSF sidelobes and reduces the angular dynamic range. In this paper we present a new method of constrained antenna placement that reduces the spatial structure in the baseline distribution. This method not only outperforms random placement algorithms that avoid exclusion zones, but surprisingly outperforms random placement algorithms without constraints to provide what we believe are the smoothest constrained baseline distributions developed to date. We use our new algorithm to determine antenna placements for the originally planned MWA, and present the antenna locations, baseline distribution and snapshot PSF for this array choice.
Published: 2012

48. First Spectroscopic Imaging Observations of the Sun at Low Radio Frequencies with the Murchison Widefield Array Prototype

Author: Oberoi, D., Matthews, L., Cairns, I., Emrich, David, Lobzin, V., Lonsdale, C., Morgan, E., Prabu, T., Vedantham, H., Wayth, Randall, Williams, A., Williams, C., White, S., Allen, G., Arcus, Wayne, Barnes, D., Benkevitch, L., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Burns, S., Cappallo, R., Clark, M., Corey, B., Dawson, M., DeBoer, D., De Gans, A., DeSouza, L., Derome, M., Edgar, R., Elton, T., Goeke, R., Gopalakrishna, M., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kamini, P., Kaplan, D., Kasper, J., Kennedy, R., Kincaid, B., Kocz, J., Koeing, R., Kowald, E., Lynch, Mervyn, Madhavi, S., McWhirter, S., Mitchell, D., Morales, M., Ng, A., Ord, Stephen, Pathikulangara, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Schinckel, A., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Thakkar, D., Tingay, Steven, Tuthill, J., Vaccarella, A., Waterson, Mark, Webster, R., Whitney, A., Oberoi, D., Matthews, L., Cairns, I., Emrich, David, Lobzin, V., Lonsdale, C., Morgan, E., Prabu, T., Vedantham, H., Wayth, Randall, Williams, A., Williams, C., White, S., Allen, G., Arcus, Wayne, Barnes, D., Benkevitch, L., Bernardi, G., Bowman, J., Briggs, F., Bunton, J., Burns, S., Cappallo, R., Clark, M., Corey, B., Dawson, M., DeBoer, D., De Gans, A., DeSouza, L., Derome, M., Edgar, R., Elton, T., Goeke, R., Gopalakrishna, M., Greenhill, L., Hazelton, B., Herne, David, Hewitt, J., Kamini, P., Kaplan, D., Kasper, J., Kennedy, R., Kincaid, B., Kocz, J., Koeing, R., Kowald, E., Lynch, Mervyn, Madhavi, S., McWhirter, S., Mitchell, D., Morales, M., Ng, A., Ord, Stephen, Pathikulangara, J., Rogers, A., Roshi, A., Salah, J., Sault, R., Schinckel, A., Udaya Shankar, N., Srivani, K., Stevens, J., Subrahmanyan, R., Thakkar, D., Tingay, Steven, Tuthill, J., Vaccarella, A., Waterson, Mark, Webster, R., and Whitney, A.
Abstract: We present the first spectroscopic images of solar radio transients from the prototype for the Murchison Widefield Array, observed on 2010 March 27. Our observations span the instantaneous frequency band 170.9– 201.6 MHz. Though our observing period is characterized as a period of “low” to “medium” activity, one broadband emission feature and numerous short-lived, narrowband, non-thermal emission features are evident. Our data represent a significant advance in low radio frequency solar imaging, enabling us to follow the spatial, spectral, and temporal evolution of events simultaneously and in unprecedented detail. The rich variety of features seen here reaffirms the coronal diagnostic capability of low radio frequency emission and provides an early glimpse of the nature of radio observations that will become available as the next generation of low-frequency radio interferometers come online over the next few years.
Published: 2011

49. Interferometric Imaging with the 32 Element Murchison Wide-Field Array

Author: Ord, S., Mitchell, D., Wayth, Randall, Greenhill, L., Bernadi, G., Gleadow, A., Edgar, R.G., Clarke, M.A., Allen, G., Arcus, Wayne, Benkevitch, L., Bowman, J.D., Briggs, F.H., Bunton, J.D., Burns, S., Cappallo, R.J., Coles, W.A., Corey, B.E., DeSouza, L., Doeleman, S.S., Derome, M., Deshpande, A., Emrich, D., Goeke, M.R., Gopalakrishna, M.R., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Madhavi, S., Matejek, M., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Roshi, A., Salah, J., Schinkel, A., Udaya, S.N., Srivani, K., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Ord, S., Mitchell, D., Wayth, Randall, Greenhill, L., Bernadi, G., Gleadow, A., Edgar, R.G., Clarke, M.A., Allen, G., Arcus, Wayne, Benkevitch, L., Bowman, J.D., Briggs, F.H., Bunton, J.D., Burns, S., Cappallo, R.J., Coles, W.A., Corey, B.E., DeSouza, L., Doeleman, S.S., Derome, M., Deshpande, A., Emrich, D., Goeke, M.R., Gopalakrishna, M.R., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C., Lynch, Mervyn, McWhirter, S., Madhavi, S., Matejek, M., Morales, M., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Roshi, A., Salah, J., Schinkel, A., Udaya, S.N., Srivani, K., Stevens, J., Tingay, Steven, Vaccarella, A., and Waterson, Mark
Abstract: The Murchison Wide-Field Array (MWA) is a low-frequency radio telescope, currently under construction, intended to search for the spectral signature of the epoch of reionization (EOR) and to probe the structure of the solar corona. Sited in western Australia, the full MWA will comprise 8192 dipoles grouped into 512 tiles and will be capable of imaging the sky south of 40° declination, from 80 MHz to 300 MHz with an instantaneous field of view that is tens of degrees wide and a resolution of a few arcminutes. A 32 station prototype of the MWA has been recently commissioned and a set of observations has been taken that exercise the whole acquisition and processing pipeline. We present Stokes I, Q, and U images from two ~4 hr integrations of a field 20° wide centered on Pictoris A. These images demonstrate the capacity and stability of a real-time calibration and imaging technique employing the weighted addition of warped snapshots to counter extreme wide-field imaging distortions.
Published: 2010

50. The Murchison Widefield Array

Author: RFI2010, Mitchell, Daniel A., Greenhill, Lincoln J., Ord, Stephen M., Bernardi, Gianni, Wayth, Randall B., Edgar, Richard G., Clarke, Michael A., Dale, Kevin, Pfister, Hanspeter, Gleadow, Stewart J., Arcus, Wayne, Briggs, F.H., Benkevitch, L., Bowman, J.D., Bunton, J.D., Burns, S., Cappallo, R.J., Corey, B.E., de Oliveira-Costa, A., Desouza, L., Doeleman, S.S., Derome, M.F., Emrich, David, Glossop, Mark, Goeke, R., Gopala Krishna, M.R., Hazelton, B., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C.J., Lynch, M.J., Madhavi, S., Matejek, M., McWhirter, S.R., Morales, M.F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Webster, R.L., Whitney, A.R., Williams, A., Williams, C., RFI2010, Mitchell, Daniel A., Greenhill, Lincoln J., Ord, Stephen M., Bernardi, Gianni, Wayth, Randall B., Edgar, Richard G., Clarke, Michael A., Dale, Kevin, Pfister, Hanspeter, Gleadow, Stewart J., Arcus, Wayne, Briggs, F.H., Benkevitch, L., Bowman, J.D., Bunton, J.D., Burns, S., Cappallo, R.J., Corey, B.E., de Oliveira-Costa, A., Desouza, L., Doeleman, S.S., Derome, M.F., Emrich, David, Glossop, Mark, Goeke, R., Gopala Krishna, M.R., Hazelton, B., Herne, David, Hewitt, J.N., Kamini, P.A., Kaplan, D.L., Kasper, J.C., Kincaid, B.B., Kocz, J., Kowald, E., Kratzenberg, E., Kumar, D., Lonsdale, C.J., Lynch, M.J., Madhavi, S., Matejek, M., McWhirter, S.R., Morales, M.F., Morgan, E., Oberoi, D., Pathikulangara, J., Prabu, T., Rogers, A., Salah, J.E., Sault, R.J., Udaya Shankar, N., Srivani, K.S., Stevens, J., Tingay, Steven, Vaccarella, A., Waterson, Mark, Webster, R.L., Whitney, A.R., Williams, A., and Williams, C.
Published: 2010

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