We present the full source catalogue from the Australia Telescope 20 GHz (AT20G) Survey. The AT20G is a blind radio survey carried out at 20 GHz with the Australia Telescope Compact Array (ATCA) from ...2004 to 2008, and covers the whole sky south of declination 0°. The AT20G source catalogue presented here is an order of magnitude larger than any previous catalogue of high-frequency radio sources, and includes 5890 sources above a 20 GHz flux-density limit of 40 mJy. All AT20G sources have total intensity and polarization measured at 20 GHz, and most sources south of declination −15° also have near-simultaneous flux-density measurements at 5 and 8 GHz. A total of 1559 sources were detected in polarized total intensity at one or more of the three frequencies. The completeness of the AT20G source catalogue is 91 per cent above 100 mJy beam−1 and 79 per cent above 50 mJy beam−1 in regions south of declination −15°. North of −15°, some observations of sources between 14 and 20 h in right ascension were lost due to bad weather and could not be repeated, so the catalogue completeness is lower in this region. Each detected source was visually inspected as part of our quality control process, and so the reliability of the final catalogue is essentially 100 per cent. We detect a small but significant population of non-thermal sources that are either undetected or have only weak detections in low-frequency catalogues. We introduce the term Ultra-Inverted Spectrum to describe these radio sources, which have a spectral index α(5, 20) > +0.7 and which constitute roughly 1.2 per cent of the AT20G sample. The 20 GHz flux densities measured for the strongest AT20G sources are in excellent agreement with the Wilkinson Microwave Anisotropy Probe (WMAP) 5-year source catalogue of Wright et al., and we find that the WMAP source catalogue is close to complete for sources stronger than 1.5 Jy at 23 GHz.
We present the first results from the Australia Telescope Large Area Survey, which consists of deep radio observations of a 3.7 deg2 field surrounding the Chandra Deep Field-South, largely coincident ...with the infrared Spitzer Wide-Area Infrared Extragalactic (SWIRE) Survey. We also list cross-identifications to infrared and optical photometry data from SWIRE, and ground-based optical spectroscopy. A total of 784 radio components are identified, corresponding to 726 distinct radio sources, nearly all of which are identified with SWIRE sources. Of the radio sources with measured redshifts, most lie in the redshift range 0.5-2 and include both star-forming galaxies and active galactic nuclei. We identify a rare population of infrared-faint radio sources that are bright at radio wavelengths but are not seen in the available optical, infrared, or X-ray data. Such rare classes of sources can only be discovered in wide, deep surveys such as this.
Background: the types of visual impairment followings stroke are wide ranging and encompass low vision, eye movement and visual field abnormalities, and visual perceptual difficuilties. Objective: ...the purpose of this paper is to present a 1-year data set and identify the types of visual impairment occurring following stroke and their prevalence. Methods: a multi-centre prospective observation study was undertaken in 14 acute trust hospitals. Stroke survivors with a suspected visual difficulty were recruited. Standardised screening/referral and investigation forms were employed to document data on visual impairment specifically assessment of visual acuity, ocular pathology, eye alignment and movement, visual perception (including inattention) and visual field defects. Results: three hundred and twenty-three patients were recruited with a mean age of 69 years standard deviation (SD) 15. Sixty-eight per cent had eye alignment/movement impairment, 49% had visual field impairment, 26.5% had low vision and 20.5% had perceptual difficulties. Conclusions: of patients referred with a suspected visual difficulty, only 8% had normal vision status confirmed on examination. Ninety-two per cent had visual impairment of some form confirmed which is considerably higher than previous publications and probably relates to the prospective, standardised investigation offered by specialist orthoptists. However, under-ascertainment of visual problems cannot be ruled out.
ABSTRACT The Australia Telescope 20GHz (AT20G) survey is a blind survey of the whole Southern sky at 20GHz with follow-up observations at 4.8, 8.6 and 20 GHz carried out with the Australia Telescope ...Compact Array (ATCA) from 2004 to 2008. In this paper we present an analysis of radio spectral properties in total intensity and polarization, sizes, optical identifications and redshifts of the sample of the 5808 extragalactic sources in the survey catalogue of confirmed sources over 6.1 sr in the Southern sky (i.e. the whole Southern sky excluding the strip at Galactic latitude |b| < ). The sample has a flux density limit of 40mJy. Completeness has been measured as a function of scan region and flux density. Averaging over the whole survey area the follow-up survey is 78 per cent complete above 50mJy and 93 per cent complete above 100mJy. 3332 sources with declination δ < -15° have good quality almost simultaneous observations at 4.8, 8.6 and 20GHz. The spectral analysis shows that the sample is dominated by flat-spectrum sources, with 69 per cent having spectral index α208.6 > - 0.5 (Sνα). The fraction of flat-spectrum sources decreases from 81 per cent for S20GHz > 500 mJy to 60 per cent for S20GHz < 100 mJy. There is also a clear spectral steepening at higher frequencies with the median α decreasing from -0.16 between 4.8 and 8.6 GHz to -0.28 between 8.6 and 20 GHz. Simultaneous observations in polarization are available for all the sources at all the frequencies. 768 sources have a good-quality detection of polarized flux density at 20 GHz; 467 of them were also detected in polarization at 4.8 and/or at 8.6 GHz so that it has been possible to compare the spectral behaviour in total intensity and polarization. We have found that the polarized fraction increases slightly with frequency and decreases with flux density. The spectral indices in total intensity and in polarization are, on average, close to each other, but we also found several sources for which the spectral shape of the polarized emission is substantially different from the spectral shape in total intensity. The correlation between the spectral indices in total intensity and in polarization is weaker for flat-spectrum sources. Cross-matches and comparisons have been made with other catalogues at lower radio frequencies, and in the optical, X-ray and γ-ray bands. Redshift estimates are available for 825 sources. PUBLICATION ABSTRACT
To explore the literature relating to the use of rubrics in Higher Education.
A systematic search using three databases was undertaken, the question used to guide the search strategy was: What are ...the benefits and challenges of using rubrics as part of the assessment process in Higher Education?
Three electronic databases were searched: British Education Index, Education Resources Information Centre and the Cumulative Index to Nursing and Allied Health Literature.
The review utilised an integrative approach to the retrieval and appraisal of the research. As the papers retrieved used different methodologies to explore the use of rubrics they were analysed using either thematic analysis or narrative synthesis.
Fifteen papers were identified that met the inclusion and exclusion criteria for the review, these spanned a range of disciplines including education, medicine and design. Four main themes related to the use of rubrics were identified: the reliability and validity of the rubric, student performance, students' perceptions of the rubric and the implementation of the rubric.
Student self-assessment, self-regulation and understanding of assessment criteria were all found to be enhanced by the use of rubrics. However students also reported that rubrics could be restrictive and student stress related to assessments could be increased. Student involvement in the design and implementation of a rubric was identified as being critical to their success. Rubrics were judged favourably by the studies reviewed in this paper, however they were found to be most effective when used as part of an overall assessment strategy that was co-created with students.
•Increasing student dissatisfaction with assessment and feedback is an issue of international concern in higher education.•Standardised marking rubrics have been implemented in some institutions to address this.•Rubrics are viewed favourably by both staff and students as a method of enhancing consistency in assessment.•Co creation of rubrics with student enhances their acceptability and utility.
This paper is part of a series describing the results from the Australia Telescope Hubble Deep Field-South (ATHDFS) survey obtained with the Australia Telescope Compact Array. This survey consists of ...observations at 1.4, 2.5, 5.2, and 8.7 GHz, all centered on the Hubble Deep Field-South. Here we present the first results from the extended observing campaign at 1.4 GHz. A total of 466 sources have been cataloged to a local sensitivity of 5 s (11 mJy rms). A source extraction technique is developed that (1) successfully excludes spurious sources from the final source catalogs and (2) accounts for the nonuniform noise in our image. A source catalog is presented, and the general properties of the 1.4 GHz image are discussed. We also present source counts derived from our ATHDFS 1.4 GHz catalog. Particular attention is given to ensuring that the counts are corrected for survey incompleteness and systematic effects. Our counts are consistent with other surveys (e.g., the Australia Telescope ESO Slice Project, VIRMOS, and the Phoenix Deep Field), and we find, in common with these surveys, that the HDF-N counts are systematically lower.
The Australia Telescope 20 GHz (AT20G) survey is a blind survey of the whole Southern sky at 20 GHz with follow-up observations at 4.8, 8.6 and 20 GHz carried out with the Australia Telescope Compact ...Array (ATCA) from 2004 to 2008. In this paper we present an analysis of radio spectral properties in total intensity and polarization, sizes, optical identifications and redshifts of the sample of the 5808 extragalactic sources in the survey catalogue of confirmed sources over 6.1 sr in the Southern sky (i.e. the whole Southern sky excluding the strip at Galactic latitude |b| <
).
The sample has a flux density limit of 40 mJy. Completeness has been measured as a function of scan region and flux density. Averaging over the whole survey area the follow-up survey is 78 per cent complete above 50 mJy and 93 per cent complete above 100 mJy. 3332 sources with declination δ < −15° have good quality almost simultaneous observations at 4.8, 8.6 and 20 GHz. The spectral analysis shows that the sample is dominated by flat-spectrum sources, with 69 per cent having spectral index α20
8.6 > − 0.5 (S∝να). The fraction of flat-spectrum sources decreases from 81 per cent for S
20 GHz > 500 mJy to 60 per cent for S
20 GHz < 100 mJy. There is also a clear spectral steepening at higher frequencies with the median α decreasing from −0.16 between 4.8 and 8.6 GHz to −0.28 between 8.6 and 20 GHz.
Simultaneous observations in polarization are available for all the sources at all the frequencies. 768 sources have a good-quality detection of polarized flux density at 20 GHz; 467 of them were also detected in polarization at 4.8 and/or at 8.6 GHz so that it has been possible to compare the spectral behaviour in total intensity and polarization. We have found that the polarized fraction increases slightly with frequency and decreases with flux density. The spectral indices in total intensity and in polarization are, on average, close to each other, but we also found several sources for which the spectral shape of the polarized emission is substantially different from the spectral shape in total intensity. The correlation between the spectral indices in total intensity and in polarization is weaker for flat-spectrum sources.
Cross-matches and comparisons have been made with other catalogues at lower radio frequencies, and in the optical, X-ray and γ-ray bands. Redshift estimates are available for 825 sources.
The Australia SKA Pathfinder (ASKAP) is a new telescope under development as a world-class high-dynamic-range wide-field-of-view survey instrument. It will utilize focal plane phased array feeds on ...the 36 12-m antennas that will compose the array. The large amounts of data present a huge computing challenge, and ASKAP will store data products in an archive after near real-time pipeline processing. This powerful instrument will be deployed at a new radio-quiet observatory, the Murchison Radio-astronomy Observatory in the midwest region of Western Australia, to enable sensitive surveys of the entire sky to address some of the big questions in contemporary physics. As a pathfinder for the SKA, ASKAP will demonstrate field of view enhancement and computing/processing technology as well as the operation of a large-scale radio array in a remote and radio-quiet region of Australia.
The Australia Telescope 20-GHz (AT20G) Survey is a blind survey of the whole southern sky at 20 GHz (with follow-up observations at 4.8 and 8.6 GHz) carried out with the Australia Telescope Compact ...Array from 2004 to 2007. The Bright Source Sample (BSS) is a complete flux-limited subsample of the AT20G Survey catalogue comprising 320 extragalactic ) radio sources south of δ=−15° with Jy. Of these, 218 have near simultaneous observations at 8 and 5 GHz. In this paper we present an analysis of radio spectral properties in total intensity and polarization, size, optical identifications and redshift distribution of the BSS sources. The analysis of the spectral behaviour shows spectral curvature in most sources with spectral steepening that increases at higher frequencies (the median spectral index α, assuming S∝να, decreases from α8.64.8= 0.11 between 4.8 and 8.6 GHz to α208.6=−0.16 between 8.6 and 20 GHz), even if the sample is dominated by flat spectra sources (85 per cent of the sample has α208.6 > −0.5). The almost simultaneous spectra in total intensity and polarization allowed us a comparison of the polarized and total intensity spectra: polarized fraction slightly increases with frequency, but the shapes of the spectra have little correlation. Optical identifications provided an estimation of redshift for 186 sources with a median value of 1.20 and 0.13, respectively, for QSO and galaxies.
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