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1. Australian Square Kilometre Array Pathfinder: I. System Description

Author

Hotan, A. W., Bunton, J. D., Chippendale, A. P., Whiting, M., Tuthill, J., Moss, V. A., McConnell, D., Amy, S. W., Huynh, M. T., Allison, J. R., Anderson, C. S., Bannister, K. W., Bastholm, E., Beresford, R., Bock, D. C. -J., Bolton, R., Chapman, J. M., Chow, K., Collier, J. D., Cooray, F. R., Cornwell, T. J., Diamond, P. J., Edwards, P. G., Feain, I. J., Franzen, T. M. O., George, D., Gupta, N., Hampson, G. A., Harvey-Smith, L., Hayman, D. B., Heywood, I., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Johnston, S., Kesteven, M., Kleiner, D., Koribalski, B. S., Lee-Waddell, K., Lenc, E., Lensson, E. S., Mackay, S., Mahony, E. K., McClure-Griffiths, N. M., McConigley, R., Mirtschin, P., Ng, A. K., Norris, R. P., Pearce, S. E., Phillips, C., Pilawa, M. A., Raja, W., Reynolds, J. E., Roberts, P., Roxby, D. N., Sadler, E. M., Shields, M., Schinckel, A. E. T., Serra, P., Shaw, R. D., Sweetnam, T., Troup, E. R., Tzioumis, A., Voronkov, M. A., and Westmeier, T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

In this paper we describe the system design and capabilities of the Australian Square Kilometre Array Pathfinder (ASKAP) radio telescope at the conclusion of its construction project and commencement of science operations. ASKAP is one of the first radio telescopes to deploy phased array feed (PAF) technology on a large scale, giving it an instantaneous field of view that covers 31 square degrees at 800 MHz. As a two-dimensional array of 36x12m antennas, with baselines ranging from 22m to 6km, ASKAP also has excellent snapshot imaging capability and 10 arcsecond resolution. This, combined with 288 MHz of instantaneous bandwidth and a unique third axis of rotation on each antenna, gives ASKAP the capability to create high dynamic range images of large sky areas very quickly. It is an excellent telescope for surveys between 700 MHz and 1800 MHz and is expected to facilitate great advances in our understanding of galaxy formation, cosmology and radio transients while opening new parameter space for discovery of the unknown., Comment: 38 pages, 24 figures, accepted for publication in PASA

Published
2021
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2. The Rapid ASKAP Continuum Survey I: Design and First Results

Author

McConnell, D., Hale, C. L., Lenc, E., Banfield, J. K., Heald, George, Hotan, A. W., Leung, James K., Moss, Vanessa A., Murphy, Tara, O'Brien, Andrew, Pritchard, Joshua, Raja, Wasim, Sadler, Elaine M., Stewart, Adam, Thomson, Alec J. M., Whiting, M., Allison, James R., Amy, S. W., Anderson, C., Ball, Lewis, Bannister, Keith W., Bell, Martin, Bock, Douglas C. -J., Bolton, Russ, Bunton, J. D., Chippendale, A. P., Collier, J. D., Cooray, F. R., Cornwell, T. J., Diamond, P. J., Edwards, P. G., Gupta, N., Hayman, Douglas B., Heywood, Ian, Jackson, C. A., Koribalski, Bärbel S., Lee-Waddell, Karen, McClure-Griffiths, N. M., Ng, Alan, Norris, Ray P., Phillips, Chris, Reynolds, John E., Roxby, Daniel N., Schinckel, Antony E. T., Shields, Matt, Tremblay, Chenoa, Tzioumis, A., Voronkov, M. A., and Westmeier, Tobias

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

The Rapid ASKAP Continuum Survey (RACS) is the first large-area survey to be conducted with the full 36-antenna Australian Square Kilometre Array Pathfinder (ASKAP) telescope. RACS will provide a shallow model of the ASKAP sky that will aid the calibration of future deep ASKAP surveys. RACS will cover the whole sky visible from the ASKAP site in Western Australia, and will cover the full ASKAP band of $700-1800$ MHz. The RACS images are generally deeper than the existing NRAO VLA Sky Survey (NVSS) and Sydney University Molonglo Sky Survey (SUMSS) radio surveys and have better spatial resolution. All RACS survey products will be public, including radio images (with $\sim 15$ arcsecond resolution) and catalogues of about three million source components with spectral index and polarisation information. In this paper, we present a description of the RACS survey and the first data release of 903 images covering the sky south of declination $+41^\circ$ made over a 288 MHz band centred at 887.5 MHz., Comment: 24 pages, 17 figures, 4 tables. For associated data see https://data.csiro.au/collections/domain/casdaObservation/results/PRAS110%20-%20The%20Rapid%20ASKAP%20Continuum

Published
2020
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3. An ultra-wide bandwidth (704 to 4032 MHz) receiver for the Parkes radio telescope

Author

Hobbs, G., Manchester, R. N., Dunning, A., Jameson, A., Roberts, P., George, D., Green, J. A., Tuthill, J., Toomey, L., Kaczmarek, J. F., Mader, S., Marquarding, M., Ahmed, A., Amy, S. W., Bailes, M., Beresford, R., Bhat, N. D. R., Bock, D. C. -J., Bourne, M., Bowen, M., Brothers, M., Cameron, A. D., Carretti, E., Carter, N., Castillo, S., Chekkala, R., Cheng, W., Chung, Y., Craig, D. A., Dai, S., Dawson, J. R., Dempsey, J., Doherty, P., Dong, B., Edwards, P. G., Ergesh, T., Gao, X. Y., Han, J. L., Hayman, D. B., Indermuehle, B. T., Jeganathan, K., Johnston, S., Kanoniuk, H., Kesteven, M., Kramer, M., Leach, M., Mcintyre, V. J., Moss, V. A., Oslowski, S., Phillips, C. J., Pope, N. C., Preisig, B., Price, D. C., Reeves, K., Reilly, L., Reynolds, J. E., Robishaw, T., Roush, P., Ruckley, T., Sadler, E. M., Sarkissian, J., Severs, S., Shannon, R. M., Smart, K. W., Smith, M., Sobey, S. L. Smith. C., Staveley-Smith, L., Tzioumis, A. K., van Straten, W., Wang, N., Wen, L., and Whiting, M. T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe an ultra-wide-bandwidth, low-frequency receiver ("UWL") recently installed on the Parkes radio telescope. The receiver system provides continuous frequency coverage from 704 to 4032 MHz. For much of the band (~60%) the system temperature is approximately 22K and the receiver system remains in a linear regime even in the presence of strong mobile phone transmissions. We discuss the scientific and technical aspects of the new receiver including its astronomical objectives, as well as the feed, receiver, digitiser and signal-processor design. We describe the pipeline routines that form the archive-ready data products and how those data files can be accessed from the archives. The system performance is quantified including the system noise and linearity, beam shape, antenna efficiency, polarisation calibration and timing stability., Comment: submitted to PASA

Published
2019
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4. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

Author

McConnell, D., Allison, J. R., Bannister, K., Bell, M. E., Bignall, H. E., Chippendale, A. P., Edwards, P. G., Harvey-Smith, L., Hegarty, S., Heywood, I., Hotan, A. W., Indermuehle, B. T., Lenc, E., Marvil, J., Popping, A., Raja, W., Reynolds, J. E., Sault, R. J., Serra, P., Voronkov, M. A., Whiting, M., Amy, S. W., Axtens, P., Ball, L., Bateman, T. J., Bock, D. C. -J., Bolton, R., Brodrick, D., Brothers, M., Brown, A. J., Bunton, J. D., Cheng, W., Cornwell, T., DeBoer, D., Feain, I., Gough, R., Gupta, N., Guzman, J. C., Hampson, G. A., Hay, S., Hayman, D. B., Hoyle, S., Humphreys, B., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Joseph, J., Koribalski, B. S., Leach, M., Lensson, E. S., MacLeod, A., Mackay, S., Marquarding, M., McClure-Griffiths, N. M., Mirtschin, P., Mitchell, D., Neuhold, S., Ng, A., Norris, R., Pearce, S., Qiao, R. Y., Schinckel, A. E. T., Shields, M., Shimwell, T. W., Storey, M., Troup, E., Turner, B., Tuthill, J., Tzioumis, A., Wark, R. M., Westmeier, T., Wilson, C., and Wilson, T.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We describe the performance of the Boolardy Engineering Test Array (BETA), the prototype for the Australian Square Kilometre Array Pathfinder telescope ASKAP. BETA is the first aperture synthesis radio telescope to use phased array feed technology, giving it the ability to electronically form up to nine dual-polarization beams. We report the methods developed for forming and measuring the beams, and the adaptations that have been made to the traditional calibration and imaging procedures in order to allow BETA to function as a multi-beam aperture synthesis telescope. We describe the commissioning of the instrument and present details of BETA's performance: sensitivity, beam characteristics, polarimetric properties and image quality. We summarise the astronomical science that it has produced and draw lessons from operating BETA that will be relevant to the commissioning and operation of the final ASKAP telescope., Comment: Accepted for publication in PASA

Published
2016
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5. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107-5907

Author

Hobbs, G., Heywood, I., Bell, M. E., Kerr, M., Rowlinson, A., Johnston, S., Shannon, R. M., Voronkov, M. A., Ward, C., Banyer, J., Hancock, P. J., Murphy, Tara, Allison, J. R., Amy, S. W., Ball, L., Bannister, K., Bock, D. C. -J., Brodrick, D., Brothers, M., Brown, A. J., Bunton, J. D., Chapman, J., Chippendale, A. P., Chung, Y., DeBoer, D., Diamond, P., Edwards, P. G., Ekers, R., Ferris, R. H., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Harvey-Smith, L., Hay, S., Hayman, D. B., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B., Jacka, C. E., Jackson, C. A., Jackson, S., Jeganathan, K., Joseph, J, Kendall, R., Kiraly, D., Koribalski, B., Leach, M., Lenc, E., MacLeod, A., Mader, S., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Neuhold, S., Ng, A., Norris, R. P., O'Sullivan, J., Pearce, S., Phillips, C. J., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A. E. T., Serra, P., Shaw, R., Shimwell, T. W., Storey, M., Sweetnam, A. W., Tzioumis, A., Westmeier, T., Whiting, M., and Wilson, C. D.

Subjects
Astrophysics - Solar and Stellar Astrophysics, Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

We use observations from the Boolardy Engineering Test Array (BETA) of the Australian Square Kilometre Array Pathfinder (ASKAP) telescope to search for transient radio sources in the field around the intermittent pulsar PSR J1107-5907. The pulsar is thought to switch between an "off" state in which no emission is detectable, a weak state and a strong state. We ran three independent transient detection pipelines on two-minute snapshot images from a 13 hour BETA observation in order to 1) study the emission from the pulsar, 2) search for other transient emission from elsewhere in the image and 3) to compare the results from the different transient detection pipelines. The pulsar was easily detected as a transient source and, over the course of the observations, it switched into the strong state three times giving a typical timescale between the strong emission states of 3.7 hours. After the first switch it remained in the strong state for almost 40 minutes. The other strong states lasted less than 4 minutes. The second state change was confirmed using observations with the Parkes radio telescope. No other transient events were found and we place constraints on the surface density of such events on these timescales. The high sensitivity Parkes observations enabled us to detect individual bright pulses during the weak state and to study the strong state over a wide observing band. We conclude by showing that future transient surveys with ASKAP will have the potential to probe the intermittent pulsar population., Comment: Accepted by MNRAS

Published
2015
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6. ASKAP HI imaging of the galaxy group IC 1459

Author

Serra, P., Koribalski, B., Kilborn, V., Allison, J. R., Amy, S. W., Ball, L., Bannister, K., Bell, M. E., Bock, D. C. -J., Bolton, R., Bowen, M., Boyle, B., Broadhurst, S., Brodrick, D., Brothers, M., Bunton, J. D., Chapman, J., Cheng, W., Chippendale, A. P., Chung, Y., Cooray, F., Cornwell, T., DeBoer, D., Diamond, P., Forsyth, R., Gough, R., Gupta, N., Hampson, G. A., Harvey-Smith, L., Hay, S., Hayman, D. B., Heywood, I., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B., Jacka, C., Jackson, C. A., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J, Kamphuis, P., Leach, M., Lenc, E., Lensson, E., Mackay, S., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Meyer, M., Mirtschin, P., Neuhold, S., Ng, A., Norris, R. P., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A. E. T., Shaw, R., Shimwell, T. W., Staveley-Smith, L., Storey, M., Sweetnam, A. W., Troup, E., Tzioumis, A., Voronkov, M. A., Westmeier, T., Whiting, M., Wilson, C., Wong, O. I., and Wu, X.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We present HI imaging of the galaxy group IC 1459 carried out with six antennas of the Australian SKA Pathfinder equipped with phased-array feeds. We detect and resolve HI in eleven galaxies down to a column density of $\sim10^{20}$ cm$^{-2}$ inside a ~6 deg$^2$ field and with a resolution of ~1 arcmin on the sky and ~8 km/s in velocity. We present HI images, velocity fields and integrated spectra of all detections, and highlight the discovery of three HI clouds -- two in the proximity of the galaxy IC 5270 and one close to NGC 7418. Each cloud has an HI mass of $10^9$ M$_\odot$ and accounts for ~15% of the HI associated with its host galaxy. Available images at ultraviolet, optical and infrared wavelengths do not reveal any clear stellar counterpart of any of the clouds, suggesting that they are not gas-rich dwarf neighbours of IC 5270 and NGC 7418. Using Parkes data we find evidence of additional extended, low-column-density HI emission around IC 5270, indicating that the clouds are the tip of the iceberg of a larger system of gas surrounding this galaxy. This result adds to the body of evidence on the presence of intra-group gas within the IC 1459 group. Altogether, the HI found outside galaxies in this group amounts to several times $10^9$ M$_\odot$, at least 10% of the HI contained inside galaxies. This suggests a substantial flow of gas in and out of galaxies during the several billion years of the group's evolution., Comment: MNRAS accepted

Published
2015
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7. Discovery of HI gas in a young radio galaxy at $z = 0.44$ using the Australian Square Kilometre Array Pathfinder

Author

Allison, J. R., Sadler, E. M., Moss, V. A., Whiting, M. T., Hunstead, R. W., Pracy, M. B., Curran, S. J., Croom, S. M., Glowacki, M., Morganti, R., Shabala, S. S., Zwaan, M. A., Allen, G., Amy, S. W., Axtens, P., Ball, L., Bannister, K. W., Barker, S., Bell, M. E., Bock, D. C. -J., Bolton, R., Bowen, M., Boyle, B., Braun, R., Broadhurst, S., Brodrick, D., Brothers, M., Brown, A., Bunton, J. D., Cantrall, C., Chapman, J., Cheng, W., Chippendale, A. P., Chung, Y., Cooray, F., Cornwell, T., DeBoer, D., Diamond, P., Edwards, P. G., Ekers, R., Feain, I., Ferris, R. H., Forsyth, R., Gough, R., Grancea, A., Gupta, N., Guzman, J. C., Hampson, G., Harvey-Smith, L., Haskins, C., Hay, S., Hayman, D. B., Heywood, I., Hotan, A. W., Hoyle, S., Humphreys, B., Indermuehle, B. T., Jacka, C., Jackson, C., Jackson, S., Jeganathan, K., Johnston, S., Joseph, J., Kendall, R., Kesteven, M., Kiraly, D., Koribalski, B. S., Leach, M., Lenc, E., Lensson, E., Mackay, S., Macleod, A., Marquarding, M., Marvil, J., McClure-Griffiths, N., McConnell, D., Mirtschin, P., Norris, R. P., Neuhold, S., Ng, A., O'Sullivan, J., Pathikulangara, J., Pearce, S., Phillips, C., Popping, A., Qiao, R. Y., Reynolds, J. E., Roberts, P., Sault, R. J., Schinckel, A., Serra, P., Shaw, R., Shields, M., Shimwell, T., Storey, M., Sweetnam, T., Troup, E., Turner, B., Tuthill, J., Tzioumis, A., Voronkov, M. A., Westmeier, T., and Wilson, C. D.

Subjects
Astrophysics - Astrophysics of Galaxies
Abstract

We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5 - 1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between $z = 0.4$ and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at $z = 0.44$ towards the GHz-peaked spectrum radio source PKS B1740$-$517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow OIII emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the \emph{XMM-Newton} satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s$^{-1}$ and fractional depths from 0.2 to 20 per cent. In addition to systemic HI gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of $v \sim 300$ km s$^{-1}$. We infer that the expanding young radio source ($t_{\rm age} \approx 2500$ yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of $\sim$ 1 $\mathrm{M}_{\odot}$ yr$^{-1}$., Comment: 18 pages, 11 figures, accepted for publication in MNRAS

Published
2015
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8. Evolution of the pc-scale structure of PKS 1934-638 revisited: first science with the ASKAP and New Zealand telescopes

Author

Tzioumis, A. K, Tingay, S. J., Stansby, B., Reynolds, J. E., Phillips, C. J., Amy, S. W., Edwards, P. G., Bowen, M. A., Leach, M. R., Kesteven, M. J., Chung, Y., Stevens, J., Forsyth, A. R., Gulyaev, S., Natush, T., Macquart, J. -P., Reynolds, C., Wayth, R. B., Bignall, H. E., Hotan, A., Hotan, C., Ellingsen, S., Dickey, J., Blanchard, J., and Lovell, J. E. J.

Subjects
Astrophysics - Cosmology and Extragalactic Astrophysics, Astrophysics - Galaxy Astrophysics
Abstract

We have studied the archetypal Gigahertz Peaked Spectrum radio galaxy, PKS 1934-638, using the Australian Long Baseline Array, augmented with two new telescopes that greatly improve the angular resolution of the array. These VLBI observations represent the first scientific results from a new antenna in NZ and the first antenna of the Australian SKA Pathfinder (ASKAP). A compact double radio source, PKS 1934-638, has been monitored over a period of 40 years, and the observation described here provides the latest datum, eight years after the previous observation, to aid in the study of the long-term evolution of the source structure. We take advantage of these new long baselines to probe PKS 1934-638 at the relatively low frequency of 1.4 GHz, in order to examine the effects of optical depth on the structure of the radio source. Optical depth effects, resulting in the observation of frequency dependent structure, may have previously been interpreted in terms of an expansion of the source as a function of time. Expansion and frequency dependent effects are important to disentangle in order to estimate the age of PKS 1934-638. We show that frequency dependent structure effects are likely to be important in PKS 1934-638 and present a simple two-dimensional synchrotron source model in which opacity effects due to synchrotron self-absorption are taken into account. Evidence for expansion of the radio source over 40 years is therefore weak, with consequences for the estimated age of the radio source., Comment: 18 pages, 5 figures. Accepted for publication in AJ

Published
2010
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9. VLBI observations of the 6.7 and 12.2 GHz methanol masers associated with NGC 6334F

Author

Ellingsen, S. P., Norris, R. P., Diamond, P. J., McCulloch, P. M., Amy, S. W., Beasley, A. J., Ferris, R. H., Gough, R. G., King, E. A., Lovell, J. E. J., Reynolds, J. E., Tzioumis, A. K., Troup, E. R., Wark, R. M., and Wieringa, M. H.

Subjects
Astrophysics
Abstract

We present milliarcsecond resolution images of the 6.7 and 12.2 GHz methanol maser emission associated with the well-known star formation region NGC 6334F. The images agree well with previous lower resolution observations, but detect approximately double the number of spots seen in the earlier work. Comparison of the relative positions of the 6.7 and 12.2 GHz maser spots shows that five of them are coincident to within the positional accuracy of these observations (approximately 4 milli-arcsec). Menten et al. (1992) observed similar positional coincidence for W3(OH) and in each case the flux density of the 6.7 GHz maser spot was greater than that of the 12.2 GHz methanol maser spot. However, for NGC 6334F several of the coincident maser spots have a larger flux density at 12.2 GHz than at 6.7 GHz. We also detected several 12.2 GHz methanol maser spots with no coincident 6.7 GHz emission. This implies that, although the 6.7 GHz methanol masers usually have a greater flux density than their 12.2 GHz counterparts, regions within the gas cloud exist where the conditions are more favourable for 12.2 than for 6.7 GHz methanol maser emission. If the conditions which give rise to the various observed ratios can be determined, then VLBI images of class II methanol masers will allow the physical conditions of the star formation region to be probed with unprecedented resolution., Comment: LaTeX, 10 Pages, including 3 figures, astron.sty included, To appear in the proceedings of the Third Asia-Pacific Telescope Workshop (Sydney, Dec 4-7 1995)

Published
1996

10. The sub-parsec-scale structure and evolution of the jet in centaurus A

Author

Tingay, S. J., Jauncey, D. L., Preston, R. A., Reynolds, J. E., Tzioumis, A. K., Lovell, J. E. J., Costa, M. E., Murphy, D. W., Meier, D. L., McCulloch, P. M., Jones, D. L., Amy, S. W., Clay, R. W., Edwards, P. G., Ellingsen, S. P., Ferris, R. H., Gough, R. G., Harbison, P., Jones, P. A., King, E. A., Kemball, A. J., Migenes, V., Nicolson, G. D., Sinclair, M. W., van Ommen, T. D., Wark, R. M., White, G. L., and Kundt, Wolfgang, editor

Published
1996
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11. The Southern Hemisphere VLBI Experiment program, SHEVE

Author

Jauncey, D. L., Reynolds, J. E., Tzioumis, A. K., Ferris, R. H., Norris, R. P., Sinclair, M. W., Migenes, V., Gough, R. G., Wark, R. M., Preston, R. A., Meier, D. L., Murphy, D. W., Jones, D. L., Hoard, D. W., St John, Mary E., Skjerve, L., King, E. A., Mcculloch, P. M., Lovell, J. E. J., Hamilton, P. A., Costa, M. E., Blair, D. G., Edwards, P., Clay, R. W., Campbell-Wilson, D., Amy, S. W., Mcadam, W. B., White, G. L., Jones, P. A., Nicolson, G. D., Robertson, J. G., editor, and Tango, W. J., editor

Published
1994
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12. Australian square kilometre array pathfinder: I. system description

Author

Hotan, A. W., primary, Bunton, J. D., additional, Chippendale, A. P., additional, Whiting, M., additional, Tuthill, J., additional, Moss, V. A., additional, McConnell, D., additional, Amy, S. W., additional, Huynh, M. T., additional, Allison, J. R., additional, Anderson, C. S., additional, Bannister, K. W., additional, Bastholm, E., additional, Beresford, R., additional, Bock, D. C.-J., additional, Bolton, R., additional, Chapman, J. M., additional, Chow, K., additional, Collier, J. D., additional, Cooray, F. R., additional, Cornwell, T. J., additional, Diamond, P. J., additional, Edwards, P. G., additional, Feain, I. J., additional, Franzen, T. M. O., additional, George, D., additional, Gupta, N., additional, Hampson, G. A., additional, Harvey-Smith, L., additional, Hayman, D. B., additional, Heywood, I., additional, Jacka, C., additional, Jackson, C. A., additional, Jackson, S., additional, Jeganathan, K., additional, Johnston, S., additional, Kesteven, M., additional, Kleiner, D., additional, Koribalski, B. S., additional, Lee-Waddell, K., additional, Lenc, E., additional, Lensson, E. S., additional, Mackay, S., additional, Mahony, E. K., additional, McClure-Griffiths, N. M., additional, McConigley, R., additional, Mirtschin, P., additional, Ng, A. K., additional, Norris, R. P., additional, Pearce, S. E., additional, Phillips, C., additional, Pilawa, M. A., additional, Raja, W., additional, Reynolds, J. E., additional, Roberts, P., additional, Roxby, D. N., additional, Sadler, E. M., additional, Shields, M., additional, Schinckel, A. E. T., additional, Serra, P., additional, Shaw, R. D., additional, Sweetnam, T., additional, Troup, E. R., additional, Tzioumis, A., additional, Voronkov, M. A., additional, and Westmeier, T., additional

Published
2021
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13. Subparsec-Scale Structure and Evolution of Centaurus A (NGC5128)

Author

Jauncey, D. L., Tingay, S. J., Preston, R. A., Reynolds, J. E., Lovell, J. E. J., McCulloch, P. M., Tzioumis, A. K., Costa, M. E., Murphy, D. W., Meier, D. L., Jones, D. L., Amy, S. W., Biggs, J. D., Blair, D. G., Clay, R. W., Edwards, P. G., Ellingsen, S. P., Ferris, R. H., Gough, R. G., Harbison, P., Jones, P. A., King, E. A., Kemball, A. J., Migenes, V., Nicolson, G. D., Sinclair, M. W., Ommen, T. V., Wark, R. M., and White, G. L.

Published
1995

14. The Rapid ASKAP Continuum Survey I: Design and first results

Author

McConnell, D., primary, Hale, C. L., additional, Lenc, E., additional, Banfield, J. K., additional, Heald, George, additional, Hotan, A. W., additional, Leung, James K., additional, Moss, Vanessa A., additional, Murphy, Tara, additional, O’Brien, Andrew, additional, Pritchard, Joshua, additional, Raja, Wasim, additional, Sadler, Elaine M., additional, Stewart, Adam, additional, Thomson, Alec J. M., additional, Whiting, M., additional, Allison, James R., additional, Amy, S. W., additional, Anderson, C., additional, Ball, Lewis, additional, Bannister, Keith W., additional, Bell, Martin, additional, Bock, Douglas C.-J., additional, Bolton, Russ, additional, Bunton, J. D., additional, Chippendale, A. P., additional, Collier, J. D., additional, Cooray, F. R., additional, Cornwell, T. J., additional, Diamond, P. J., additional, Edwards, P. G., additional, Gupta, N., additional, Hayman, Douglas B., additional, Heywood, Ian, additional, Jackson, C. A., additional, Koribalski, Bärbel S., additional, Lee-Waddell, Karen, additional, McClure-Griffiths, N. M., additional, Ng, Alan, additional, Norris, Ray P., additional, Phillips, Chris, additional, Reynolds, John E., additional, Roxby, Daniel N., additional, Schinckel, Antony E. T., additional, Shields, Matt, additional, Tremblay, Chenoa, additional, Tzioumis, A., additional, Voronkov, M. A., additional, and Westmeier, Tobias, additional

Published
2020
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17. Centaurus A, the core of the problem

Author

Tingay, S. J, Jauncey, D. L, Preston, R. A, Reynolds, J. E, Meier, D. L, Tzioumis, A. K, Jones, D. L, King, E. A, Amy, S. W, and Biggs, J. D

Subjects
Astronomy
Abstract

The bright, peculiar elliptical galaxy Centaurus A (NGC 5128, PKS 1322-427) was one of the first extragalactic radio sources to be optically identified (Bolton et al. 1949). At a distance of 4 Mpc, Centaurus A is the closest active radio galaxy and affords the highest linear imaging resolution (1 mas approximately equal to 0.02 pc) and hence the best prospects for studying an active nucleus close to the central radio source. We present the results of multi-epoch, 8.4-GHz, very long baseline interferometry (VLBI), imaging observations of the nucleus made over the past three years. The nucleus possesses a core-jet structure where the inner portion of the jet shows apparent linear motion with a velocity substantially less than the speed of light.

Published
1994

18. The Southern Hemisphere VLBI Experiment (SHEVE)

Author

Preston, R. A, Jauncey, D. L, King, E. A, Jones, D. L, Ferris, R. H, Hoard, D. W, Campbell-Wilson, D, Gwinn, C. R, Jones, P. A, Lovell, J. E. J, Norris, R. P, John, M. E. St, Meier, D. L, Murphy, D. W, Costa, M. E, Amy, S. W, Clay, R. W, Hamilton, P. A, Kemball, A. J, McAdam, W. B, Perlman, E, Skjerve, L, White, G. L, and Reynolds, J. E

Subjects
Communications And Radar
Abstract

Radio telescopes at eight sites in Astralia and one in South Africa operate as a VLBI array during several periods each year.

Published
1992

19. Comparison between self-assembling peptide nanofiber scaffold (SAPNS) and fibrin sealant in neurosurgical hemostasis

Author

Fei-Fan, Xu, Yue-Chun, Wang, Stella, Sun, Amy S W, Ho, Derek, Lee, Karrie M Y, Kiang, Xiao-Qin, Zhang, Wai-Man, Lui, Bai-Yun, Liu, Wu-Tian, Wu, and Gilberto K K, Leung

Subjects
Wound Healing, Time Factors, Administration, Topical, Nanofibers, Fibrin Tissue Adhesive, Hemostasis, Surgical, Hemostatics, Neurosurgical Procedures, Rats, Sprague-Dawley, Disease Models, Animal, Brain Injuries, Original Research Articles, Animals, Peptides
Abstract

RADA16‐I is a synthetic type I self‐assembling peptide nanofiber scaffold (SAPNS) which may serve as a novel biocompatible hemostatic agent. Its application in neurosurgical hemostasis, however, has not been explored. Although RADA16‐I is nontoxic and nonimmunogenic, its intrinsic acidity may potentially provoke inflammation in the surgically injured brain. We conducted an animal study to compare RADA16‐I with fibrin sealant, a commonly used agent, with the hypothesis that the former would be a comparable alternative. Using a standardized surgical brain injury model, 30 Sprague–Dawley rats were randomized into three treatment groups: RADA16‐I, fibrin sealant or gelatin sponge (control). Animals were sacrificed on day 3 and 42. Astrocytic and microglial infiltrations within the cerebral parenchyma adjacent to the operative site were significantly lower in the RADA16‐I and fibrin sealant groups than control. RADA16‐I did not cause more cellular inflammatory response despite its acidity when compared with fibrin sealant. Immunohistochemical studies showed infiltration by astrocytes and microglia into the fibrin sealant and RADA16‐I grafts, suggesting their potential uses as tissue scaffolds. RADA16‐I is a promising candidate for further translational and clinical studies that focus on its applications as a safe and effective hemostat, proregenerative nanofiber scaffold as well as drug and cell carrier.

Published
2015

20. Hyperoxia resensitizes chemoresistant glioblastoma cells to temozolomide through unfolded protein response

Author

Derek, Lee, Stella, Sun, Amy S W, Ho, Karrie M Y, Kiang, Xiao Qin, Zhang, Fei Fan, Xu, and Gilberto K K, Leung

Subjects
Brain Neoplasms, Blotting, Western, Procollagen-Proline Dioxygenase, Protein Disulfide-Isomerases, Apoptosis, Hyperoxia, Endoplasmic Reticulum Stress, Combined Modality Therapy, Dacarbazine, Drug Resistance, Neoplasm, Temozolomide, Tumor Cells, Cultured, Unfolded Protein Response, Humans, Glioblastoma, Antineoplastic Agents, Alkylating, Cell Proliferation
Abstract

Intratumoural hypoxia is associated with chemoresistance in glioblastoma multiforme (GBM), a highly malignant brain tumour. Adaptive response to endoplasmic reticulum stress induced by temozolomide is a major obstacle in recurrent GBM. We investigated whether hyperoxia resensitizes temozolomide-resistant GBM cells to temozolomide by abrogating the hypoxia-induced, unfolded protein response (UPR)-related protective mechanisms.We examined changes to key UPR modulators in temozolomide-sensitive and -resistant human GBM cells (D54 and U87) treated with/without temozolomide at different oxygen concentrations using western blotting, and cytotoxic benefits of overexpressing key chaperone, P4HB, in GBM cells (U87 and U251) under normoxia and hyperoxia.Hyperoxia, alone or synergistically with temozolomide, activated the UPR in sensitive and resistant D54 and U87 cell lines. Hyperoxia also reduced survival benefit of U87 and U251 cells with P4HB overexpression through the UPR.Hyperoxia enhanced GBM cell sensitivity to temozolomide, likely through UPR, highlighting an important treatment modality targeting chemosensitive and -resistant GBM.

Published
2014

21. A pilot ASKAP survey of radio transient events in the region around the intermittent pulsar PSR J1107−5907

Author

Hobbs, G., primary, Heywood, I., additional, Bell, M. E., additional, Kerr, M., additional, Rowlinson, A., additional, Johnston, S., additional, Shannon, R. M., additional, Voronkov, M. A., additional, Ward, C., additional, Banyer, J., additional, Hancock, P. J., additional, Murphy, Tara, additional, Allison, J. R., additional, Amy, S. W., additional, Ball, L., additional, Bannister,  K., additional, Bock, D. C.-J., additional, Brodrick, D., additional, Brothers, M., additional, Brown, A. J., additional, Bunton, J. D., additional, Chapman, J., additional, Chippendale, A. P., additional, Chung, Y., additional, DeBoer, D., additional, Diamond, P., additional, Edwards, P. G., additional, Ekers, R., additional, Ferris, R. H., additional, Forsyth, R., additional, Gough, R., additional, Grancea, A., additional, Gupta, N., additional, Harvey-Smith, L., additional, Hay, S., additional, Hayman, D. B., additional, Hotan, A. W., additional, Hoyle, S., additional, Humphreys, B., additional, Indermuehle, B., additional, Jacka, C. E., additional, Jackson, C. A., additional, Jackson, S., additional, Jeganathan, K., additional, Joseph, J, additional, Kendall, R., additional, Kiraly, D., additional, Koribalski, B., additional, Leach, M., additional, Lenc, E., additional, MacLeod, A., additional, Mader, S., additional, Marquarding, M., additional, Marvil, J., additional, McClure-Griffiths, N., additional, McConnell, D., additional, Mirtschin, P., additional, Neuhold, S., additional, Ng, A., additional, Norris, R. P., additional, O'Sullivan, J., additional, Pearce, S., additional, Phillips, C. J., additional, Popping, A., additional, Qiao, R. Y., additional, Reynolds, J. E., additional, Roberts, P., additional, Sault, R. J., additional, Schinckel, A. E. T., additional, Serra, P., additional, Shaw, R., additional, Shimwell, T. W., additional, Storey, M., additional, Sweetnam, A. W., additional, Tzioumis, A., additional, Westmeier, T., additional, Whiting, M., additional, and Wilson, C. D., additional

Published
2016
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22. The Australian Square Kilometre Array Pathfinder: Performance of the Boolardy Engineering Test Array

Author

McConnell, D., primary, Allison, J. R., additional, Bannister, K., additional, Bell, M. E., additional, Bignall, H. E., additional, Chippendale, A. P., additional, Edwards, P. G., additional, Harvey-Smith, L., additional, Hegarty, S., additional, Heywood, I., additional, Hotan, A. W., additional, Indermuehle, B. T., additional, Lenc, E., additional, Marvil, J., additional, Popping, A., additional, Raja, W., additional, Reynolds, J. E., additional, Sault, R. J., additional, Serra, P., additional, Voronkov, M. A., additional, Whiting, M., additional, Amy, S. W., additional, Axtens, P., additional, Ball, L., additional, Bateman, T. J., additional, Bock, D. C.-J., additional, Bolton, R., additional, Brodrick, D., additional, Brothers, M., additional, Brown, A. J., additional, Bunton, J. D., additional, Cheng, W., additional, Cornwell, T., additional, DeBoer, D., additional, Feain, I., additional, Gough, R., additional, Gupta, N., additional, Guzman, J. C., additional, Hampson, G. A., additional, Hay, S., additional, Hayman, D. B., additional, Hoyle, S., additional, Humphreys, B., additional, Jacka, C., additional, Jackson, C. A., additional, Jackson, S., additional, Jeganathan, K., additional, Joseph, J., additional, Koribalski, B. S., additional, Leach, M., additional, Lensson, E. S., additional, MacLeod, A., additional, Mackay, S., additional, Marquarding, M., additional, McClure-Griffiths, N. M., additional, Mirtschin, P., additional, Mitchell, D., additional, Neuhold, S., additional, Ng, A., additional, Norris, R., additional, Pearce, S., additional, Qiao, R. Y., additional, Schinckel, A. E. T., additional, Shields, M., additional, Shimwell, T. W., additional, Storey, M., additional, Troup, E., additional, Turner, B., additional, Tuthill, J., additional, Tzioumis, A., additional, Wark, R. M., additional, Westmeier, T., additional, Wilson, C., additional, and Wilson, T., additional

Published
2016
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23. Erratum: Discovery of H i gas in a young radio galaxy at $\boldsymbol {z = 0.44}$ using the Australian Square Kilometre Array Pathfinder

Author

Allison, J. R., primary, Sadler, E. M., additional, Moss, V. A., additional, Whiting, M. T., additional, Hunstead, R. W., additional, Pracy, M. B., additional, Curran, S. J., additional, Croom, S. M., additional, Glowacki, M., additional, Morganti, R., additional, Shabala, S. S., additional, Zwaan, M. A., additional, Allen, G., additional, Amy, S. W., additional, Axtens, P., additional, Ball, L., additional, Bannister, K. W., additional, Barker, S., additional, Bell, M. E., additional, Bock, D. C.-J., additional, Bolton, R., additional, Bowen, M., additional, Boyle, B., additional, Braun, R., additional, Broadhurst, S., additional, Brodrick, D., additional, Brothers, M., additional, Brown, A., additional, Bunton, J. D., additional, Cantrall, C., additional, Chapman, J., additional, Cheng, W., additional, Chippendale, A. P., additional, Chung, Y., additional, Cooray, F., additional, Cornwell, T., additional, DeBoer, D., additional, Diamond, P., additional, Edwards, P. G., additional, Ekers, R., additional, Feain, I., additional, Ferris, R. H., additional, Forsyth, R., additional, Gough, R., additional, Grancea, A., additional, Gupta, N., additional, Guzman, J. C., additional, Hampson, G., additional, Harvey-Smith, L., additional, Haskins, C., additional, Hay, S., additional, Hayman, D. B., additional, Heywood, I., additional, Hotan, A. W., additional, Hoyle, S., additional, Humphreys, B., additional, Indermuehle, B. T., additional, Jacka, C., additional, Jackson, C., additional, Jackson, S., additional, Jeganathan, K., additional, Johnston, S., additional, Joseph, J., additional, Kendall, R., additional, Kesteven, M., additional, Kiraly, D., additional, Koribalski, B. S., additional, Leach, M., additional, Lenc, E., additional, Lensson, E., additional, Mackay, S., additional, Macleod, A., additional, Marquarding, M., additional, Marvil, J., additional, McClure-Griffiths, N., additional, McConnell, D., additional, Mirtschin, P., additional, Norris, R. P., additional, Neuhold, S., additional, Ng, A., additional, O'Sullivan, J., additional, Pathikulangara, J., additional, Pearce, S., additional, Phillips, C., additional, Popping, A., additional, Qiao, R. Y., additional, Reynolds, J. E., additional, Roberts, P., additional, Sault, R. J., additional, Schinckel, A., additional, Serra, P., additional, Shaw, R., additional, Shields, M., additional, Shimwell, T., additional, Storey, M., additional, Sweetnam, T., additional, Troup, E., additional, Turner, B., additional, Tuthill, J., additional, Tzioumis, A., additional, Voronkov, M. A., additional, Westmeier, T., additional, and Wilson, C. D., additional

Published
2015
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24. Discovery of H i gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder

Author

Allison, J. R., primary, Sadler, E. M., additional, Moss, V. A., additional, Whiting, M. T., additional, Hunstead, R. W., additional, Pracy, M. B., additional, Curran, S. J., additional, Croom, S. M., additional, Glowacki, M., additional, Morganti, R., additional, Shabala, S. S., additional, Zwaan, M. A., additional, Allen, G., additional, Amy, S. W., additional, Axtens, P., additional, Ball, L., additional, Bannister, K. W., additional, Barker, S., additional, Bell, M. E., additional, Bock, D. C.-J., additional, Bolton, R., additional, Bowen, M., additional, Boyle, B., additional, Braun, R., additional, Broadhurst, S., additional, Brodrick, D., additional, Brothers, M., additional, Brown, A., additional, Bunton, J. D., additional, Cantrall, C., additional, Chapman, J., additional, Cheng, W., additional, Chippendale, A. P., additional, Chung, Y., additional, Cooray, F., additional, Cornwell, T., additional, DeBoer, D., additional, Diamond, P., additional, Edwards, P. G., additional, Ekers, R., additional, Feain, I., additional, Ferris, R. H., additional, Forsyth, R., additional, Gough, R., additional, Grancea, A., additional, Gupta, N., additional, Guzman, J. C., additional, Hampson, G., additional, Harvey-Smith, L., additional, Haskins, C., additional, Hay, S., additional, Hayman, D. B., additional, Heywood, I., additional, Hotan, A. W., additional, Hoyle, S., additional, Humphreys, B., additional, Indermuehle, B. T., additional, Jacka, C., additional, Jackson, C., additional, Jackson, S., additional, Jeganathan, K., additional, Johnston, S., additional, Joseph, J., additional, Kendall, R., additional, Kesteven, M., additional, Kiraly, D., additional, Koribalski, B. S., additional, Leach, M., additional, Lenc, E., additional, Lensson, E., additional, Mackay, S., additional, Macleod, A., additional, Marquarding, M., additional, Marvil, J., additional, McClure-Griffiths, N., additional, McConnell, D., additional, Mirtschin, P., additional, Norris, R. P., additional, Neuhold, S., additional, Ng, A., additional, O'Sullivan, J., additional, Pathikulangara, J., additional, Pearce, S., additional, Phillips, C., additional, Popping, A., additional, Qiao, R. Y., additional, Reynolds, J. E., additional, Roberts, P., additional, Sault, R. J., additional, Schinckel, A., additional, Serra, P., additional, Shaw, R., additional, Shields, M., additional, Shimwell, T., additional, Storey, M., additional, Sweetnam, T., additional, Troup, E., additional, Turner, B., additional, Tuthill, J., additional, Tzioumis, A., additional, Voronkov, M. A., additional, Westmeier, T., additional, and Wilson, C. D., additional

Published
2015
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25. ASKAP H i imaging of the galaxy group IC 1459

Author

Serra, P., primary, Koribalski, B., additional, Kilborn, V., additional, Allison, J. R., additional, Amy, S. W., additional, Ball, L., additional, Bannister, K., additional, Bell, M. E., additional, Bock, D. C.-J., additional, Bolton, R., additional, Bowen, M., additional, Boyle, B., additional, Broadhurst, S., additional, Brodrick, D., additional, Brothers, M., additional, Bunton, J. D., additional, Chapman, J., additional, Cheng, W., additional, Chippendale, A. P., additional, Chung, Y., additional, Cooray, F., additional, Cornwell, T., additional, DeBoer, D., additional, Diamond, P., additional, Forsyth, R., additional, Gough, R., additional, Gupta, N., additional, Hampson, G. A., additional, Harvey-Smith, L., additional, Hay, S., additional, Hayman, D. B., additional, Heywood, I., additional, Hotan, A. W., additional, Hoyle, S., additional, Humphreys, B., additional, Indermuehle, B., additional, Jacka, C., additional, Jackson, C. A., additional, Jackson, S., additional, Jeganathan, K., additional, Johnston, S., additional, Joseph, J., additional, Kamphuis, P., additional, Leach, M., additional, Lenc, E., additional, Lensson, E., additional, Mackay, S., additional, Marquarding, M., additional, Marvil, J., additional, McClure-Griffiths, N., additional, McConnell, D., additional, Meyer, M., additional, Mirtschin, P., additional, Neuhold, S., additional, Ng, A., additional, Norris, R. P., additional, O'Sullivan, J., additional, Pathikulangara, J., additional, Pearce, S., additional, Phillips, C., additional, Popping, A., additional, Qiao, R. Y., additional, Reynolds, J. E., additional, Roberts, P., additional, Sault, R. J., additional, Schinckel, A. E. T., additional, Shaw, R., additional, Shimwell, T. W., additional, Staveley-Smith, L., additional, Storey, M., additional, Sweetnam, A. W., additional, Troup, E., additional, Tzioumis, A., additional, Voronkov, M. A., additional, Westmeier, T., additional, Whiting, M., additional, Wilson, C., additional, Wong, O. I., additional, and Wu, X., additional

Published
2015
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27. VLBI observations of the 6.7 and 12.2 GHz methanol masers associated with NGC 6334F

Author

Simon Ellingsen, Norris, R. P., Diamond, P. J., Mcculloch, P. M., Amy, S. W., Beasley, A. J., Ferris, R. H., Gough, R. G., King, E. A., Lovell, J. E. J., Reynolds, J. E., Tzioumis, A. K., Troup, E. R., Wark, R. M., and Wieringa, M. H.

Subjects
Astrophysics (astro-ph), Astrophysics::Instrumentation and Methods for Astrophysics, Astrophysics::Solar and Stellar Astrophysics, FOS: Physical sciences, Astrophysics::Cosmology and Extragalactic Astrophysics, Physics::Chemical Physics, Astrophysics, Astrophysics::Galaxy Astrophysics
Abstract

We present milliarcsecond resolution images of the 6.7 and 12.2 GHz methanol maser emission associated with the well-known star formation region NGC 6334F. The images agree well with previous lower resolution observations, but detect approximately double the number of spots seen in the earlier work. Comparison of the relative positions of the 6.7 and 12.2 GHz maser spots shows that five of them are coincident to within the positional accuracy of these observations (approximately 4 milli-arcsec). Menten et al. (1992) observed similar positional coincidence for W3(OH) and in each case the flux density of the 6.7 GHz maser spot was greater than that of the 12.2 GHz methanol maser spot. However, for NGC 6334F several of the coincident maser spots have a larger flux density at 12.2 GHz than at 6.7 GHz. We also detected several 12.2 GHz methanol maser spots with no coincident 6.7 GHz emission. This implies that, although the 6.7 GHz methanol masers usually have a greater flux density than their 12.2 GHz counterparts, regions within the gas cloud exist where the conditions are more favourable for 12.2 than for 6.7 GHz methanol maser emission. If the conditions which give rise to the various observed ratios can be determined, then VLBI images of class II methanol masers will allow the physical conditions of the star formation region to be probed with unprecedented resolution., Comment: LaTeX, 10 Pages, including 3 figures, astron.sty included, To appear in the proceedings of the Third Asia-Pacific Telescope Workshop (Sydney, Dec 4-7 1995)

Published
1996
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28. EVOLUTION OF THE PARSEC-SCALE STRUCTURE OF PKS 1934–638 REVISITED: FIRST SCIENCE WITH THE ASKAP AND NEW ZEALAND TELESCOPES

Author

Tzioumis, A. K., primary, Tingay, S. J., additional, Stansby, B., additional, Reynolds, J. E., additional, Phillips, C. J., additional, Amy, S. W., additional, Edwards, P. G., additional, Bowen, M. A., additional, Leach, M. R., additional, Kesteven, M. J., additional, Chung, Y., additional, Stevens, J., additional, Forsyth, A. R., additional, Gulyaev, S., additional, Natusch, T., additional, Macquart, J.-P., additional, Reynolds, C., additional, Wayth, R. B., additional, Bignall, H. E., additional, Hotan, A., additional, Hotan, C., additional, Godfrey, L., additional, Ellingsen, S., additional, Dickey, J., additional, Blanchard, J., additional, and Lovell, J. E. J., additional

Published
2010
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29. Detection of compact radio emission from Circinus X-1 with the first Southern hemisphere e-VLBI experiment

Author

Phillips, C. J., primary, Deller, A., additional, Amy, S. W., additional, Tingay, S. J., additional, Tzioumis, A. K., additional, Reynolds, J. E., additional, Jauncey, D. L., additional, Stevens, J., additional, Ellingsen, S. P., additional, Dickey, J., additional, Fender, R. P., additional, Tudose, V., additional, and Nicolson, G. D., additional

Published
2007
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30. Discovery of HI gas in a young radio galaxy at z = 0.44 using the Australian Square Kilometre Array Pathfinder.

Author

Allison, J. R., Sadler, E. M., Moss, V. A., Whiting, M. T., Hunstead, R. W., Pracy, M. B., Curran, S. J., Croom, S. M., Glowacki, M., Morganti, R., Shabala, S. S., Zwaan, M. A., Allen, G., Amy, S. W., Axtens, P., Ball, L., Bannister, K. W., Barker, S., Bell, M. E., and Bock, D. C.-J.

Subjects
GALAXIES, SOLAR system, ASTROPHYSICS, ABSORPTION, RADIO lines, DATA analysis
Abstract

We report the discovery of a new 21-cm HI absorption system using commissioning data from the Boolardy Engineering Test Array of the Australian Square Kilometre Array Pathfinder (ASKAP). Using the 711.5-1015.5 MHz band of ASKAP we were able to conduct a blind search for the 21-cm line in a continuous redshift range between z = 0.4 and 1.0, which has, until now, remained largely unexplored. The absorption line is detected at z = 0.44 towards the GHz-peaked spectrum radio source PKS B1740-517 and demonstrates ASKAP's excellent capability for performing a future wide-field survey for HI absorption at these redshifts. Optical spectroscopy and imaging using the Gemini-South telescope indicates that the HI gas is intrinsic to the host galaxy of the radio source. The narrow [OIII] emission lines show clear double-peaked structure, indicating either large-scale outflow or rotation of the ionized gas. Archival data from the XMM-Newton satellite exhibit an absorbed X-ray spectrum that is consistent with a high column density obscuring medium around the active galactic nucleus. The HI absorption profile is complex, with four distinct components ranging in width from 5 to 300 km s-1 and fractional depths from 0.2 to 20 per cent. In addition to systemic HI gas, in a circumnuclear disc or ring structure aligned with the radio jet, we find evidence for a possible broad outflow of neutral gas moving at a radial velocity of v ~ 300 km s-1. We infer that the expanding young radio source (tage 2500 yr) is cocooned within a dense medium and may be driving circumnuclear neutral gas in an outflow of ~1 M⊙ yr-1. [ABSTRACT FROM AUTHOR]

Published
2015
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32. The Southern Hemisphere VLBI Experiment Program, SHEVE

Author

Jauncey, D. L., primary, Reynolds, J. E., additional, Tzioumis, A. K., additional, Ferris, R. H., additional, Norris, R. P., additional, Sinclair, M. W., additional, Migenes, V., additional, Gough, R. G., additional, Wark, R. M., additional, Preston, R. A., additional, Meier, D. L., additional, Murphy, D. W., additional, Jones, D. L., additional, Hoard, D. W., additional, St John, Mary E., additional, Skjerve, L., additional, King, E. A., additional, McCulloch, P. M., additional, Lovell, J. E. J., additional, Hamilton, P. A., additional, Costa, M. E., additional, Blair, D. G., additional, Edwards, P., additional, Clay, R. W., additional, Campbell-Wilson, D., additional, Amy, S. W., additional, McAdam, W. B., additional, White, G. L., additional, Jones, P. A., additional, and Nicolson, G. D., additional

Published
1994
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35. A Search for Transient Events at 843 MHz

Author

Amy, S. W., Large, M. I., and Vaughan, A. E.

Abstract

AbstractThe Molonglo Observatory Synthesis Telescope is equipped with a transient event monitoring system which operates during normal synthesis observations. The device is designed to respond to impulsive signals which occur within the passband (843.0 ± 1.5 MHz) with time scales between 0.001 ms and 800 ms. The multiple beam facility of the telescope provides some discrimination against local interference. An upper limit of 1.7 × 10-2events s-1sr-1has been placed on celestial events with durations between 1 ms and 25 ms and energy density = 10-28J m-2Hz-1. The monitoring system has been recently reconfigured to improve the recognition and rejection of impulsive signals of non-celestial origin.

Published
1989
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36. e-VLBI detection of Circinus X-1 at 1.6 and 8.4 GHz

Author

Deller, A., Phillips, C., Amy, S. W., Tzioumis, A. K., Reynolds, J. E., Jauncey, D. L., Stevens, J., Simon Ellingsen, Dickey, J., Fender, R., Nicolson, G. D., Tingay, S. J., Tudose, V., and High Energy Astrophys. & Astropart. Phys (API, FNWI)

Abstract

Following the return of Circinus X-1 to a recurrent radio flaring state (last seen in 1975 - 1985: ATel #563, #985) we have performed e-VLBI observations on the source at 1.6 and 8.4 GHz using an Australian array of radio telescopes (Parkes, ATCA, Mopra, and Hobart). e-VLBI allows rapid response to transient events and real-time analysis of VLBI data, in this case implemented by transfer of data between telescopes via optical fibres and software correlation on a PC cluster.

37. Endoplasmic reticulum chaperone prolyl 4-hydroxylase, beta polypeptide (P4HB) promotes malignant phenotypes in glioma via MAPK signaling.

Author

Sun S, Kiang KMY, Ho ASW, Lee D, Poon MW, Xu FF, Pu JKS, Kan ANC, Lee NPY, Liu XB, Man K, Day PJR, Lui WM, Fung CF, and Leung GKK

Abstract

Endoplasmic reticulum (ER) chaperone Prolyl 4-hydroxylase, beta polypeptide (P4HB) has previously been identified as a novel target for chemoresistance in glioblastoma multiforme (GBM). Yet its functional roles in glioma carcinogenesis remain elusive. In clinical analysis using human glioma specimens and Gene Expression Omnibus (GEO) profiles, we found that aberrant expression of P4HB was correlated with high-grade malignancy and an angiogenic phenotype in glioma. Furthermore, P4HB upregulation conferred malignant characteristics including proliferation, invasion, migration and angiogenesis in vitro , and increased tumor growth in vivo via the mitogen-activated protein kinase (MAPK) signaling pathway. Pathway analysis suggested genetic and pharmacologic inhibition of P4HB suppressed MAPK expression and its downstream targets were involved in angiogenesis and invasion. This is the first study that demonstrates the oncogenic roles of P4HB and its underlying mechanism in glioma. Since tumor invasion and Vascularisation are typical hallmarks in malignant glioma, our findings uncover a promising anti-glioma mechanism through P4HB-mediated retardation of MAPK signal transduction., Competing Interests: CONFLICTS OF INTEREST All authors declare no conflicts of interest.

Published
2017
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38. Comparison between self-assembling peptide nanofiber scaffold (SAPNS) and fibrin sealant in neurosurgical hemostasis.

Author

Xu FF, Wang YC, Sun S, Ho AS, Lee D, Kiang KM, Zhang XQ, Lui WM, Liu BY, Wu WT, and Leung GK

Subjects
Administration, Topical, Animals, Brain Injuries pathology, Disease Models, Animal, Fibrin Tissue Adhesive administration & dosage, Fibrin Tissue Adhesive toxicity, Hemostasis, Surgical adverse effects, Hemostatics administration & dosage, Hemostatics toxicity, Peptides administration & dosage, Peptides toxicity, Rats, Sprague-Dawley, Time Factors, Brain Injuries drug therapy, Brain Injuries surgery, Fibrin Tissue Adhesive pharmacology, Hemostasis, Surgical methods, Hemostatics pharmacology, Nanofibers, Neurosurgical Procedures, Peptides pharmacology, Wound Healing drug effects
Abstract

RADA16-I is a synthetic type I self-assembling peptide nanofiber scaffold (SAPNS) which may serve as a novel biocompatible hemostatic agent. Its application in neurosurgical hemostasis, however, has not been explored. Although RADA16-I is nontoxic and nonimmunogenic, its intrinsic acidity may potentially provoke inflammation in the surgically injured brain. We conducted an animal study to compare RADA16-I with fibrin sealant, a commonly used agent, with the hypothesis that the former would be a comparable alternative. Using a standardized surgical brain injury model, 30 Sprague-Dawley rats were randomized into three treatment groups: RADA16-I, fibrin sealant or gelatin sponge (control). Animals were sacrificed on day 3 and 42. Astrocytic and microglial infiltrations within the cerebral parenchyma adjacent to the operative site were significantly lower in the RADA16-I and fibrin sealant groups than control. RADA16-I did not cause more cellular inflammatory response despite its acidity when compared with fibrin sealant. Immunohistochemical studies showed infiltration by astrocytes and microglia into the fibrin sealant and RADA16-I grafts, suggesting their potential uses as tissue scaffolds. RADA16-I is a promising candidate for further translational and clinical studies that focus on its applications as a safe and effective hemostat, proregenerative nanofiber scaffold as well as drug and cell carrier., (© 2015 Wiley Periodicals, Inc.)

Published
2015
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39. MicroRNA-210 and Endoplasmic Reticulum Chaperones in the Regulation of Chemoresistance in Glioblastoma.

Author

Lee D, Sun S, Zhang XQ, Zhang PD, Ho AS, Kiang KM, Fung CF, Lui WM, and Leung GK

Abstract

Glioblastoma multiforme (GBM) is the commonest primary brain tumour in adults characterized by relentless recurrence due to resistance towards the standard chemotherapeutic agent temozolomide (TMZ). Prolyl 4-hydroxylase, beta polypeptide (P4HB), an endoplasmic reticulum (ER) chaperone, is known to be upregulated in TMZ-resistant GBM cells. MicroRNAs (miRNAs) are non-protein-coding transcripts that may play important roles in GBM chemoresistance. We surmised that miRNA dysregulations may contribute to P4HB upregulation, hence chemoresistance. We found that miRNA-210 (miR-210) was P4HB-targeting and was highly downregulated in TMZ-resistant GBM cells. Forced overexpression of miR-210 led to P4HB downregulation and a reduction in TMZ-resistance. A reciprocal relationship between their expressions was also verified in clinical glioma specimens. Our study is the first to demonstrate a potential link between miR-210 and ER chaperone in determining chemosensitivity in GBM. The findings have important translational implications in suggesting new directions of future studies.

Published
2015
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40. Hyperoxia resensitizes chemoresistant glioblastoma cells to temozolomide through unfolded protein response.

Author

Lee D, Sun S, Ho AS, Kiang KM, Zhang XQ, Xu FF, and Leung GK

Subjects
Apoptosis drug effects, Blotting, Western, Brain Neoplasms metabolism, Brain Neoplasms pathology, Cell Proliferation drug effects, Combined Modality Therapy, Dacarbazine pharmacology, Endoplasmic Reticulum Stress drug effects, Glioblastoma metabolism, Glioblastoma pathology, Humans, Temozolomide, Tumor Cells, Cultured, Unfolded Protein Response drug effects, Antineoplastic Agents, Alkylating pharmacology, Brain Neoplasms therapy, Dacarbazine analogs & derivatives, Drug Resistance, Neoplasm, Glioblastoma therapy, Hyperoxia, Procollagen-Proline Dioxygenase metabolism, Protein Disulfide-Isomerases metabolism, Unfolded Protein Response physiology
Abstract

Background: Intratumoural hypoxia is associated with chemoresistance in glioblastoma multiforme (GBM), a highly malignant brain tumour. Adaptive response to endoplasmic reticulum stress induced by temozolomide is a major obstacle in recurrent GBM. We investigated whether hyperoxia resensitizes temozolomide-resistant GBM cells to temozolomide by abrogating the hypoxia-induced, unfolded protein response (UPR)-related protective mechanisms., Materials and Methods: We examined changes to key UPR modulators in temozolomide-sensitive and -resistant human GBM cells (D54 and U87) treated with/without temozolomide at different oxygen concentrations using western blotting, and cytotoxic benefits of overexpressing key chaperone, P4HB, in GBM cells (U87 and U251) under normoxia and hyperoxia., Results: Hyperoxia, alone or synergistically with temozolomide, activated the UPR in sensitive and resistant D54 and U87 cell lines. Hyperoxia also reduced survival benefit of U87 and U251 cells with P4HB overexpression through the UPR., Conclusion: Hyperoxia enhanced GBM cell sensitivity to temozolomide, likely through UPR, highlighting an important treatment modality targeting chemosensitive and -resistant GBM., (Copyright© 2014 International Institute of Anticancer Research (Dr. John G. Delinassios), All rights reserved.)

Published
2014

41. Inhibition of prolyl 4-hydroxylase, beta polypeptide (P4HB) attenuates temozolomide resistance in malignant glioma via the endoplasmic reticulum stress response (ERSR) pathways.

Author

Sun S, Lee D, Ho AS, Pu JK, Zhang XQ, Lee NP, Day PJ, Lui WM, Fung CF, and Leung GK

Subjects
Animals, Antineoplastic Agents, Alkylating pharmacology, Apoptosis drug effects, Blotting, Western, Brain Neoplasms metabolism, Cell Proliferation drug effects, Dacarbazine pharmacology, Flow Cytometry, Glioma metabolism, Humans, Immunoenzyme Techniques, In Situ Nick-End Labeling, Male, Mice, Mice, Inbred BALB C, Neoplasm Recurrence, Local drug therapy, Neoplasm Recurrence, Local metabolism, Procollagen-Proline Dioxygenase genetics, Procollagen-Proline Dioxygenase metabolism, Protein Disulfide-Isomerases genetics, Protein Disulfide-Isomerases metabolism, RNA, Messenger genetics, RNA, Small Interfering genetics, Real-Time Polymerase Chain Reaction, Reverse Transcriptase Polymerase Chain Reaction, Signal Transduction drug effects, Temozolomide, eIF-2 Kinase genetics, eIF-2 Kinase metabolism, Brain Neoplasms drug therapy, Dacarbazine analogs & derivatives, Drug Resistance, Neoplasm, Endoplasmic Reticulum Stress drug effects, Glioma drug therapy, Procollagen-Proline Dioxygenase antagonists & inhibitors, Protein Disulfide-Isomerases antagonists & inhibitors
Abstract

Background: Glioblastoma multiforme (GBM), the most aggressive malignant primary brain tumor of the central nervous system, is characterized by a relentless disease recurrence despite continued advancement in surgery, radiotherapy, and chemotherapy. Resistance to temozolomide (TMZ), a standard chemotherapeutic agent for GBM, remains a major challenge. Understanding the mechanisms behind TMZ resistance can direct the development of novel strategies for the prevention, monitoring, and treatment of tumor relapse., Methods and Results: Our research platform, based on the establishment of 2 pairs of TMZ-sensitive/resistant GBM cells (D54-S and D54-R; U87-S and U87-R), has successfully identified prolyl 4-hydroxylase, beta polypeptide (P4HB) over-expression to be associated with an increased IC50 of TMZ. Elevated P4HB expression was verified using in vivo xenografts developed from U87-R cells. Clinically, we found that P4HB was relatively up-regulated in the recurrent GBM specimens that were initially responsive to TMZ but later developed acquired resistance, when compared with treatment-naive tumors. Functionally, P4HB inhibition by RNAi knockdown and bacitracin inhibition could sensitize D54-R and U87-R cells to TMZ in vitro and in vivo, whereas over-expression of P4HB in vitro conferred resistance to TMZ in both D54-S and U87-S cells. Moreover, targeting P4HB blocked its protective function and sensitized glioma cells to TMZ through the PERK arm of the endoplasmic reticulum stress response., Conclusions: Our study identified a novel target together with its functional pathway in the development of TMZ resistance. P4HB inhibition may be used alone or in combination with TMZ for the treatment of TMZ-resistant GBM.

Published
2013
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