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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.
The Dark Energy Survey is undertaking an observational programme imaging 1/4 of the southern hemisphere sky with unprecedented photometric accuracy. In the process of observing millions of faint stars and galaxies to constrain the parameters of the dark energy equation of state, the Dark Energy Survey will obtain pre-discovery images of the regions surrounding an estimated 100 gamma-ray bursts over 5 yr. Once gamma-ray bursts are detected by, e.g., the Swift satellite, the DES data will be extremely useful for follow-up observations by the transient astronomy community. We describe a recently-commissioned suite of software that listens continuously for automated notices of gamma-ray burst activity, collates information from archival DES data, and disseminates relevant data products back to the community in near-real-time. Of particular importance are the opportunities that non-public DES data provide for relative photometry of the optical counterparts of gamma-ray bursts, as well as for identifying key characteristics (e.g., photometric redshifts) of potential gamma-ray burst host galaxies. We provide the functional details of the DESAlert software, and its data products, and we show sample results from the application of DESAlert to numerous previously detected gamma-ray bursts, including the possible identification of several heretofore unknown gamma-ray burst hosts.
We report on the identifications of 15 new X-ray selected Active Galactic Nuclei (AGN). The AGN have been discovered during an ongoing program to identify and study the optical counterparts of X-ray sources detected by the HEAO-1 satellite. The new AGN add to our existing data base of 26 making a sample of 41 objects which are the subject of a multiwavelength study including radio, infrared, optical, UV and X-ray observations. As part of this study 8.4 GHz flux measurements have been made at Parkes. Radio-optical-X-ray continuum spectral index comparisons are presented.
Two new integral field units (IFUs) were installed recently on the WIYN Observatory's 3.5-meter telescope at Kitt Peak. These unique IFUs contain fibers of different sizes in the same head. This design allows smaller fibers to sample regions of higher surface brightness, providing higher spatial resolution while maintaining adequate signal-to-noise (S/N). Conversely, larger fibers maintain S/N at the expense of spatial resolution in the lower surface brightness regions of galaxies. The new IFUs were built with funds from NSF award ATI-0804576.
The prognostic value of subjective memory complaints (SMCs) in the diagnosis of dementia of the Alzheimer's type is unclear. While some studies have found an association between SMCs and cognitive decline, many have found a stronger association with depression, which raises questions about their diagnostic utility.
Methods:
We examined the cross-sectional association between SMC severity (as measured using the MAC-Q, a brief SMC questionnaire) and affect, memory, and Alzheimer's disease (AD) biomarkers (β-amyloid deposition and the apolipoprotein E ε4 (APOEε4) allele) in healthy elderly controls (HC; M = 78.74 years, SD = 6.7) and individuals with mild cognitive impairment (MCI; M = 72.74 years, SD = 8.8). We analyzed a subset of individuals drawn from the Australian Imaging Biomarkers and Lifestyle (AIBL) Study of Aging.
Results:
SMCs were more severe in MCI patients than in HCs. SMC severity was related to affective variables and the interaction between age and group membership (HC/MCI). Within the HC group, SMC severity was related to affective variables only, while severity correlated only with age in the MCI group. SMCs were not related to cognitive variables or AD biomarkers.
Conclusion:
SMCs were related to solely by poorer mood (greater depressive and anxious symptomatology) in the cognitively healthy elderly however mean levels were subclinical. This finding argues for the assessment of affective symptomatology in conjunction with cognitive assessment in elderly memory complainers. Future AIBL research will focus on assessing other AD biomarkers, such as brain atrophy and Aβ plasma markers, in relation to complaint severity. Once our 36-month follow-up data are collected, we propose to assess whether SMCs can predict future cognitive decline.
Teouma, an archaeological site on Efate Island, Vanuatu, features the earliest cemetery yet discovered of the colonizers of Remote Oceania, from the late second millennium B.C. In order to investigate potential migration of seventeen human individuals, we measured isotopes of strontium (87Sr/86Sr), oxygen (δ18O), and carbon (δ13C), as well as barium (Ba) and strontium (Sr) concentrations, in tooth enamel from skeletons excavated in the first two field seasons. The majority of individuals cluster with similar isotope and Ba/Sr ratios, consistent with a diet of marine resources supplemented with plants grown on the local basaltic soils. Four outliers, with distinctive 87Sr/86Sr and δ18O, are probably immigrants, three of which were buried in a distinctive position (supine, with the head to the south) with higher Ba/Sr and δ13C, consistent with a terrestrial, nonlocal diet. Among the probable immigrants was a male buried with the crania of three of the locally raised individuals on his chest.
We verified the Bureau of Meteorology's seasonal rainfall forecasts for 262 townships throughout Australia, from its inception in June 1997 to May 2005. The results indicate that the forecasting system had low skill. Brier Skill Score and the receiver operating characteristic values were uniformly close to the no skill value. Forecast variances were consistently small. The overall observed variance was 0.0048, 2.1% of the variance of a perfect system. The estimate of the gradient of the outcome against forecast was 0.42 and was imprecise. Definitive statements about bias cannot be made. The value of the forecasts for decision-makers was estimated using value score curves, calculated for six forecast scenarios. All curves indicated that no economic benefit could have been reliably derived by users of the seasonal rainfall forecasts, with the exception of users with decisions triggered by a small shift in the forecast from climatology, in which case small economic gains may have occurred. Small value scores were associated with the observed forecast variance, not the observed bias. We examined the expected change in value scores associated with any future increase in forecast variance. This showed that a moderate increase from the observed variance would bring limited benefits. Substantial value to a broad range of users will only occur with a large increase in forecast variance. To deliver this, new lead indicators with markedly better predictive characteristics may need to be developed for the seasonal rainfall forecasting system.
A long cropmark enclosure at Springfield, Essex, interpreted as a Neolithic cursus, was investigated betwee 1979–85 to confirm its date and establish a site sequence. The enclosure was c. 690 m long and 37–49 m wide the ditch being uninterrupted in all areas examined, features within the interior at the eastern end included a incomplete ring of substantial post-pits which it is suggested originally formed a complete circle. Peterborou pottery, predominately Mortlake style, Grooved Ware, a small amount of Beaker pottery, earlier Bronze Age urn sherds, and flint artefacts of the late 3rd-early 2nd millennium were recovered from the cursus ditch an other features. Collectively the evidence indicates a prolonged period of use. The results of the excavations a described, the site is discussed in its local and regional context and the implications of the excavation for our understanding of cursus monuments are considered.
Temporalis fascia, placed as an underlay graft, is commonly used to repair tympanic membrane perforations. Graft failure, however, is a well recognized complication. Grafts are often allowed to dry out during the procedure and, therefore, are often positioned in a dry or partially dehydrated state and only become fully rehydrated after placement. This study looked at how the size of the temporalis fascia alters with its state of hydration. The size of 20 temporalis fascia grafts was measured when fresh, after flattening and allowing them to dry, and finally after rehydrating the grafts with 0.9 per cent saline solution. Significant shrinkage was demonstrated. It is therefore proposed that a cause of increased failure rates, particularly in anterior myringoplasties, is loss of underlay due to graft rehydration and shrinkage. Thus graft shrinkage should be considered when positioning the graft.
The variability of CD-24 7599 (V=11.48 mag) was discovered by JCC during observing run XCOV7 of the Whole Earth Telescope (WET, Nather et al. 1990) network in February, 1992. The star was observed as an additional target and 117 hours of high-quality temporal spectroscopic observations were obtained.
Our analysis of these data revealed the presence of 7 independent pulsation modes between 27.0 and 38.1 cycles per day (313 – 441 μHz) with semiamplitudes of 2.1 – 10.2 milli-modulation amplitudes (mma). We showed that peaks at linear combination frequencies detected in the power spectra were not due to eigenmodes excited to visible amplitude by resonant mode coupling.
We report the analysis of 154 hours of nearly continuous high-speed photometric data on the pulsating DB white dwarf (DBV) GD 358 obtained during the Whole Earth Telescope (WET) run of May 1990. The Fourier transform (FT) of the light curve is dominated by power in the range from 1200 – 1700μHz with more than 180 significant peaks in the total transform. We also see significant power at the sums and differences of the dominant frequencies, indicating the importance of nonlinear behavior. We can use this data to obtain an accurate total stellar mass, and surface He layer mass. The implied surface He layer mass, if correct, provides a significant and surprising challenge to stellar evolution theory, as well as the theory of chemical mixing.
We report our experience of submucous resection of the nasal septum under local anaesthesia as an outpatient procedure. We have audited 50 consecutive cases and compared the results with a similar group of patients in whom the operation was carried out in the usual way under general anaesthesia. We have found the procedure to be safe, effective and economically advantageous.
The near field monitoring of an auditory evoked response from the cochlear (electrocochleography) is a tried and trusted clinical tool. Conventional techniques for performing electrocochleography are cumbersome to use and frequently uncomfortable for the patient. We present a simple, modified technique which provides more flexibility with regard to where and when electrocochleography may be performed and also improves patient comfort during the test.
Aerial survey in Essex has revealed a number of elongated enclosures interpreted as either long barrows or mortuary enclosures of Neolithic date. Excavation of one of these sites at Rivenhall in 1986 produced finds of flintwork and pottery which help to substantiate this hypothesis. A surface collection survey of the field containing the enclosure produced Mesolithic and Neolithic flintwork. A short discussion considers the Essex sites in their wider context.