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We apply two methods to estimate the 21-cm bispectrum from data taken within the Epoch of Reionisation (EoR) project of the Murchison Widefield Array (MWA). Using data acquired with the Phase II compact array allows a direct bispectrum estimate to be undertaken on the multiple redundantly spaced triangles of antenna tiles, as well as an estimate based on data gridded to the uv-plane. The direct and gridded bispectrum estimators are applied to 21 h of high-band (167–197 MHz; z = 6.2–7.5) data from the 2016 and 2017 observing seasons. Analytic predictions for the bispectrum bias and variance for point-source foregrounds are derived. We compare the output of these approaches, the foreground contribution to the signal, and future prospects for measuring the bispectra with redundant and non-redundant arrays. We find that some triangle configurations yield bispectrum estimates that are consistent with the expected noise level after 10 h, while equilateral configurations are strongly foreground-dominated. Careful choice of triangle configurations may be made to reduce foreground bias that hinders power spectrum estimators, and the 21-cm bispectrum may be accessible in less time than the 21-cm power spectrum for some wave modes, with detections in hundreds of hours.
We provide the first in situ measurements of antenna element beam shapes of the Murchison Widefield Array. Most current processing pipelines use an assumed beam shape, which can cause absolute and relative flux density errors and polarisation ‘leakage’. Understanding the primary beam is then of paramount importance, especially for sensitive experiments such as a measurement of the 21-cm line from the epoch of reionisation, where the calibration requirements are so extreme that tile to tile beam variations may affect our ability to make a detection. Measuring the primary beam shape from visibilities is challenging, as multiple instrumental, atmospheric, and astrophysical factors contribute to uncertainties in the data. Building on the methods of Neben et al. [Radio Sci., 50, 614], we tap directly into the receiving elements of the telescope before any digitisation or correlation of the signal. Using ORBCOMM satellite passes we are able to produce all-sky maps for four separate tiles in the XX polarisation. We find good agreement with the beam model of Sokolowski et al. [2017, PASA, 34, e062], and clearly observe the effects of a missing dipole from a tile in one of our beam maps. We end by motivating and outlining additional on-site experiments.
We describe the motivation and design details of the ‘Phase II’ upgrade of the Murchison Widefield Array radio telescope. The expansion doubles to 256 the number of antenna tiles deployed in the array. The new antenna tiles enhance the capabilities of the Murchison Widefield Array in several key science areas. Seventy-two of the new tiles are deployed in a regular configuration near the existing array core. These new tiles enhance the surface brightness sensitivity of the array and will improve the ability of the Murchison Widefield Array to estimate the slope of the Epoch of Reionisation power spectrum by a factor of ∼3.5. The remaining 56 tiles are deployed on long baselines, doubling the maximum baseline of the array and improving the array u, v coverage. The improved imaging capabilities will provide an order of magnitude improvement in the noise floor of Murchison Widefield Array continuum images. The upgrade retains all of the features that have underpinned the Murchison Widefield Array’s success (large field of view, snapshot image quality, and pointing agility) and boosts the scientific potential with enhanced imaging capabilities and by enabling new calibration strategies.
The discovery of the first electromagnetic counterpart to a gravitational wave signal has generated follow-up observations by over 50 facilities world-wide, ushering in the new era of multi-messenger astronomy. In this paper, we present follow-up observations of the gravitational wave event GW170817 and its electromagnetic counterpart SSS17a/DLT17ck (IAU label AT2017gfo) by 14 Australian telescopes and partner observatories as part of Australian-based and Australian-led research programs. We report early- to late-time multi-wavelength observations, including optical imaging and spectroscopy, mid-infrared imaging, radio imaging, and searches for fast radio bursts. Our optical spectra reveal that the transient source emission cooled from approximately 6 400 K to 2 100 K over a 7-d period and produced no significant optical emission lines. The spectral profiles, cooling rate, and photometric light curves are consistent with the expected outburst and subsequent processes of a binary neutron star merger. Star formation in the host galaxy probably ceased at least a Gyr ago, although there is evidence for a galaxy merger. Binary pulsars with short (100 Myr) decay times are therefore unlikely progenitors, but pulsars like PSR B1534+12 with its 2.7 Gyr coalescence time could produce such a merger. The displacement (~2.2 kpc) of the binary star system from the centre of the main galaxy is not unusual for stars in the host galaxy or stars originating in the merging galaxy, and therefore any constraints on the kick velocity imparted to the progenitor are poor.
Background: Recruiting family physicians into primary care research studies requires researchers to continually manage information coming in, going out, and coming in again. In many research groups, Microsoft Excel and Access are the usual data management tools, but they are very basic and do not support any automation, linking, or reminder systems to manage and integrate recruitment information and processes. Objective: We explored whether a commercial customer relationship management (CRM) software program – designed for sales people in businesses to improve customer relations and communications – could be used to make the research recruitment system faster, more effective, and more efficient. Findings: We found that while there was potential for long-term studies, it simply did not adapt effectively enough for our shorter study and recruitment budget. The amount of training required to master the software and our need for ongoing flexible and timely support were greater than the benefit of using CRM software for our study.
The efficacy of WSSA Group 4 herbicides has been reported to vary with dependence on the time of day the application is made, which may affect the value of this mechanism of action as a control option and resistance management tool for Palmer amaranth. The objectives of this research were to evaluate the effect of time of day for application on 2,4-D and dicamba translocation and whether or not altering translocation affected any existing variation in phytotoxicity seen across application time of day. Maximum translocation (Tmax) of [14C]2,4-D and [14C]dicamba out of the treated leaf was significantly increased 52% and 29% to 34% in one of two repeated experiments for each herbicide, respectively, with application at 7:00 AM compared with applications at 2:00 PM and/or 12:00 AM. Applications at 7:00 AM increased [14C]2,4-D distribution to roots and increased [14C]dicamba distribution above the treated leaf compared with other application timings. In phytotoxicity experiments, dicamba application at 8 h after exposure to darkness (HAED) resulted in significantly lower dry root biomass than dicamba application at 8 h after exposure to light (HAEL). Contrasts indicated that injury resulting from dicamba application at 8 HAEL, corresponding to midday, was significantly reduced with a root treatment of 5-[N-(3,4-dimethoxyphenylethyl)methylamino]-2-(3,4-dimethoxyphenyl)-2-isopropylvaleronitrile hydrochloride (verapamil) compared with injury observed with dicamba application and a root treatment of verapamil at 8 HAED, which corresponded to dawn. Overall, time of application appears to potentially influence translocation of 2,4-D and dicamba. Furthermore, inhibition of translocation appears to somewhat influence variation in phytotoxicity across times of application. Therefore, translocation may be involved in the varying efficacy of WSSA Group 4 herbicides due to application time of day, which has implications for the use of this mechanism of action for effective control and resistance management of Palmer amaranth.
We describe the design and performance of the Engineering Development Array, which is a low-frequency radio telescope comprising 256 dual-polarisation dipole antennas working as a phased array. The Engineering Development Array was conceived of, developed, and deployed in just 18 months via re-use of Square Kilometre Array precursor technology and expertise, specifically from the Murchison Widefield Array radio telescope. Using drift scans and a model for the sky brightness temperature at low frequencies, we have derived the Engineering Development Array’s receiver temperature as a function of frequency. The Engineering Development Array is shown to be sky-noise limited over most of the frequency range measured between 60 and 240 MHz. By using the Engineering Development Array in interferometric mode with the Murchison Widefield Array, we used calibrated visibilities to measure the absolute sensitivity of the array. The measured array sensitivity matches very well with a model based on the array layout and measured receiver temperature. The results demonstrate the practicality and feasibility of using Murchison Widefield Array-style precursor technology for Square Kilometre Array-scale stations. The modular architecture of the Engineering Development Array allows upgrades to the array to be rolled out in a staged approach. Future improvements to the Engineering Development Array include replacing the second stage beamformer with a fully digital system, and to transition to using RF-over-fibre for the signal output from first stage beamformers.
We have compiled a catalogue of H ii regions detected with the Murchison Widefield Array between 72 and 231 MHz. The multiple frequency bands provided by the Murchison Widefield Array allow us identify the characteristic spectrum generated by the thermal Bremsstrahlung process in H ii regions. We detect 306 H ii regions between 260° < l < 340° and report on the positions, sizes, peak, integrated flux density, and spectral indices of these H ii regions. By identifying the point at which H ii regions transition from the optically thin to thick regime, we derive the physical properties including the electron density, ionised gas mass, and ionising photon flux, towards 61 H ii regions. This catalogue of H ii regions represents the most extensive and uniform low frequency survey of H ii regions in the Galaxy to date.
NASA’s Space Interferometry Mission (SIM), scheduled for launch in 2009, will determine the positions of thousands of stars as faint as V = 20 to a precision better than 4 microarcseconds (µas). A key part of the mission is the Astrometric Grid, which is a reference frame of several thousand stars with V ≤ 13 against which all relative measurements will be calibrated. To serve as a reliable inertial reference frame, the Grid must be astrometrically stable against photocenter jitter (from planets, binary companions, flaring or spotting) at the ~ 4µas level. Sub–solar metallicity giant stars, by virtue of their intrinsic luminosity, can probe the Galaxy to greater distances than almost any other stellar type at the same apparent magnitude. Thus, distant (> 3 kpc) giants with V < 13 will have proportionately smaller astrometric jitter compared to other potential Astrometric Grid star candidates. The Grid Giant Star Survey is a patchwork all-sky survey to find sub–solar metallicity K giants for the Grid, and to provide a unique database for studies of Galactic stellar populations. We describe here the survey characteristics and give examples of results to date.
Medieval English Theatre is the premier journal in early theatre studies. Its name belies its wide range of interest: it publishes articles on theatre and pageantry from across the British Isles up to the opening of the London playhouses and the suppression of the civic mystery cycles, and also includes contributions on European and Latin drama, together with analyses of modern survivals or equivalents, and of research productions of medieval plays. This volume includes essays on spectatorship, audience reception and records of early drama, especially in Scotland, besides engaging with the current interest in the Towneley Plays and the history of its manuscript.Editors: Sarah Carpenter, Pamela M. King, Meg Twycross, Greg Walker.
Volumes 37 and 38 of Medieval English Theatre offer a collection of essays to honour John McGavin. Written by his friends and colleagues, students and admirers, these all testify to the deep affection as well as the academic esteem in which John himself and his work across the discipline of early theatre are held. Many reflect his own particular interests in the early drama of England and, especially, of Scotland: its records and narratives, its spectators, its intellectual and affective strategies, and its cultural work. There are papers on many aspects of Scottish theatrical culture, from ceremonial (Williamson) to Sir David Lyndsay (Hadley Williams, Happé, and Walker); from foolery (Carpenter) to Dunbar's dramatic voice (Jack). John's abiding interest in spectatorship and audience reception is approached from different angles, in morality drama (Steenbrugge), dialogue (Bose), in the York Play (King), academic drama (Dutton), and theory (van Pelt). His authoritative work in the creative interpretation of records and narratives, of both dramatic and para-dramatic performance, is reflected in essays on coronation ceremony (Hunt), libel (Egan), and monastic crucifixion games (Klausner). His steering role in the project on Early Modern London Theatres is commemorated in the online Bear Hunt (MacLean and Hagen). Three essays engage with one of the central current concerns of early theatre study, the Towneley manuscript and its plays (Epp, Johnston, and Twycross), while two more address uniquely revealing single plays: the Digby Mary Magdalen (Godfrey), and the Welsh Troelus a Chresyd (Niebrzydowski).
John's work has indeed come to epitomise ‘the best pairt of our play’. The number of essays contributed to the collection, by scholars young and old across the whole field of early drama studies, shows the range of his influence on the discipline itself and on generations of those working within it. This collection is offered as a tribute both to his creative scholarship and his collegiality. There is no space here for all the many friends and colleagues who would like to salute him on this occasion; but we hope that the recollections of three voices, offering memories and appreciation from John's student days to the present, may speak for us all.
Medieval English Theatre Meeting 2015 Change of publication details
The 2015 METh meeting was held at the University of Southampton, hosted by John McGavin. His carefully timetabled proceedings were interrupted by the unscheduled (by him) presentation of a Festschrift in his honour. He holds the unique composite volume, but the articles it contains will be divided between this volume of METh (Part One), and Volume 38 (Part Two).
The rest of the day lived up to its festive beginning. A range of papers on the topic of ‘Paradigms Lost’ highlighted those once entrenched scholarly positions about which we have changed our minds. Pamela M. King, in ‘Medieval Drama Criticism before METh’, introduced the late nineteenth-century work of Adolphus William Ward; Garrett Epp, on ‘Things we can no longer say about the Towneley Plays’, gave an impressive PowerPoint show of deletions of accepted ‘facts’; while Meg Twycross summarised new evidence on the provenance of the manuscript (see this volume). Other speakers introduced new material which extends or changes our approach to well-worn topics: Lindsey Cox showed us the visual evidence for the portrait miniature in Wit and Science, and how the different parts of the audience might have perceived it, and Jason Burg sketched the changing patterns of performance in Lincoln Cathedral between 1309 and 1642. Nadia van Pelt reminded us of the necessity of looking at original manuscript sources rather than their calendared summaries by discussing the enigmatic detail of a letter from Chapuys which reports Henry VIII's visit to a St John's Day pageant showing him ‘cutting off the heads of the clergy’; while Greg Walker rounded off the day with a masterly summation of recent critical approaches to spectatorship, and where they fell short.
Elisabeth Dutton gave us our own spectatorly experience. Before lunch, James McBain and Stephanie Allen of the EDOX (Early Drama at Oxford University) project spoke about ‘Rehabilitating Academic Drama’, and just after lunch this was put to the test by an enthusiastic reading of the play of Narcissus originally mounted by the undergraduates of St John's College, Oxford, as a Christmas entertainment in 1602.
We compare first-order (refractive) ionospheric effects seen by the MWA with the ionosphere as inferred from GPS data. The first-order ionosphere manifests itself as a bulk position shift of the observed sources across an MWA field of view. These effects can be computed from global ionosphere maps provided by GPS analysis centres, namely the CODE. However, for precision radio astronomy applications, data from local GPS networks needs to be incorporated into ionospheric modelling. For GPS observations, the ionospheric parameters are biased by GPS receiver instrument delays, among other effects, also known as receiver DCBs. The receiver DCBs need to be estimated for any non-CODE GPS station used for ionosphere modelling. In this work, single GPS station-based ionospheric modelling is performed at a time resolution of 10 min. Also the receiver DCBs are estimated for selected Geoscience Australia GPS receivers, located at Murchison Radio Observatory, Yarragadee, Mount Magnet and Wiluna. The ionospheric gradients estimated from GPS are compared with that inferred from MWA. The ionospheric gradients at all the GPS stations show a correlation with the gradients observed with the MWA. The ionosphere estimates obtained using GPS measurements show promise in terms of providing calibration information for the MWA.
Practice-based performance measurement is fundamental for improvement and accountability in primary care. Traditional performance measurement of the patient’s experience is often too costly and cumbersome for most practices.
This scoping review explores the literature on the use of interactive voice response (IVR) telephone surveys to identify lessons for its use for collecting data on patient-reported outcome measures at the primary care practice level.
The literature suggests IVR could potentially increase the capacity to reach more representative patient samples and those traditionally most difficult to engage. There is potential for long-term cost effectiveness and significant decrease of the burden on practices involved in collecting patient survey data. Challenges such as low response rates, mode effects, high initial set-up costs and maintenance fees, are also reported and require careful attention.
This review suggests IVR may be a feasible alternative to traditional patient data collection methods, which should be further explored.
GLEAM, the GaLactic and Extragalactic All-sky MWA survey, is a survey of the entire radio sky south of declination + 25° at frequencies between 72 and 231 MHz, made with the MWA using a drift scan method that makes efficient use of the MWA’s very large field-of-view. We present the observation details, imaging strategies, and theoretical sensitivity for GLEAM. The survey ran for two years, the first year using 40-kHz frequency resolution and 0.5-s time resolution; the second year using 10-kHz frequency resolution and 2 s time resolution. The resulting image resolution and sensitivity depends on observing frequency, sky pointing, and image weighting scheme. At 154 MHz, the image resolution is approximately 2.5 × 2.2/cos (δ + 26.7°) arcmin with sensitivity to structures up to ~ 10° in angular size. We provide tables to calculate the expected thermal noise for GLEAM mosaics depending on pointing and frequency and discuss limitations to achieving theoretical noise in Stokes I images. We discuss challenges, and their solutions, that arise for GLEAM including ionospheric effects on source positions and linearly polarised emission, and the instrumental polarisation effects inherent to the MWA’s primary beam.