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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.
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.
Working canines are deployed by the Federal Emergency Management Agency (FEMA), as part of a National Disaster Response Plan. Stress associated with helicopter flight and the resulting physical effects on the dog are unknown. Our objective was to test the hypotheses that (1) helicopter travel affects the physiology and faecal microbiota of working canines, but that (2) physiological consequences of helicopter travel will not negatively affect their work performance. A total of nine FEMA canines were loaded onto helicopters and flown for 30 min in July 2015. Rectal temperature, behavioural stress indicators and saliva swabs (for cortisol) were collected at baseline, loading, mid-flight and post-flight. After flight, canines completed a standardised search exercise to monitor work performance. Faecal samples were collected for microbial DNA extraction and Illumina sequencing. All canines were on a standardised diet (CANIDAE® Grain Free PURE Land®) for 3 weeks prior to the study. Visible indicators of stress were observed at loading and at mid-flight and corresponded with an increase (P < 0·05) in salivary cortisol from 5·4 µg/l (baseline) to 6·4 µg/l (loading). Additionally, rectal temperature increased (P < 0·05) from 38·61°C (baseline) to 39·33°C (mid-flight) and 39·72°C (post-flight). Helicopter travel did not affect search performance (P > 0·05). We found that α- and β-diversity measures of faecal microbiota were not affected (P > 0·05). Our data suggest that although helicopter travel may cause physiological changes that have been associated with stress in working dogs, it does not make an impact on their search performance or the stability of faecal microbiota.
The Murchison Widefield Array is a Square Kilometre Array Precursor. The telescope is located at the Murchison Radio–astronomy Observatory in Western Australia. The MWA consists of 4 096 dipoles arranged into 128 dual polarisation aperture arrays forming a connected element interferometer that cross-correlates signals from all 256 inputs. A hybrid approach to the correlation task is employed, with some processing stages being performed by bespoke hardware, based on Field Programmable Gate Arrays, and others by Graphics Processing Units housed in general purpose rack mounted servers. The correlation capability required is approximately 8 tera floating point operations per second. The MWA has commenced operations and the correlator is generating 8.3 TB day−1 of correlation products, that are subsequently transferred 700 km from the MRO to Perth (WA) in real-time for storage and offline processing. In this paper, we outline the correlator design, signal path, and processing elements and present the data format for the internal and external interfaces.
If the marked divergence of ethnological opinion concerning the degree of racial purity or admixture of the Australian aboriginal affords evidence of anything at all, it can only be of the fact that the problems of his origin, as of his degree of racial purity, are not yet solved. Not only are there the most conflicting opinions on these points, but the cognate subjects of the origin, and degree of purity of the Tasmanian, and of his relationship, if any, to the Australian, are equally undetermined, whilst there is lastly the debatable point of the relation of both those primitive peoples to the Papuan.
The Murchison Widefield Array (MWA) is one of three Square Kilometre Array Precursor telescopes and is located at the Murchison Radio-astronomy Observatory in the Murchison Shire of the mid-west of Western Australia, a location chosen for its extremely low levels of radio frequency interference. The MWA operates at low radio frequencies, 80–300 MHz, with a processed bandwidth of 30.72 MHz for both linear polarisations, and consists of 128 aperture arrays (known as tiles) distributed over a ~3-km diameter area. Novel hybrid hardware/software correlation and a real-time imaging and calibration systems comprise the MWA signal processing backend. In this paper, the as-built MWA is described both at a system and sub-system level, the expected performance of the array is presented, and the science goals of the instrument are summarised.
In this study we report on the results of the investigation of lead iodide material properties. The effectiveness of a zone refining purification method on the material purity is determined by ICP-MS and ICP-OES and correlated to the electrical and physical material properties. We show that this zone refining method is very efficient in removing impurities from lead iodide, and we also determine the segregation coefficient for some of these impurities. Triple axis x-ray diffraction (TAD) analysis has been used to determine the crystalline perfection of the lead iodide after applying various cutting, etching and fabrication methods. The soft lead iodide crystal was found to be damaged when cleaved by a razor blade, but by using a diamond wheel saw, followed by etching, the crystallinity of the material was much improved, as observed by TAD. Low temperature photoluminescence also indicates an improvement in the material properties of the purified lead iodide. Electrical properties of lead iodide such as carrier mobility, were calculated based on carrier - phonon scattering. The results for the electrical properties were in good agreement with the experimental data.
We evaluated use of the periodically rotated overlapping parallel lines with enhanced reconstruction diffusion-weighted imaging sequence, compared with conventional echo planar magnetic resonance imaging, in the detection of middle-ear cholesteatoma.
Material and methods:
Sixteen patients awaiting second-stage combined approach tympanoplasty and three patients awaiting first-stage combined approach tympanoplasty underwent magnetic resonance imaging with both (1) the periodically rotated overlapping parallel lines with enhanced reconstruction sequence (i.e. non echo planar imaging) and (2) the array spatial sensitivity encoding technique sequence (i.e. echo planar imaging). Two neuroradiologists independently evaluated the images produced by both sequences. Radiology findings were correlated with surgical findings.
Results and analysis:
Seven cholesteatomas were found at surgery. Neither of the assessed imaging sequences were able to detect cholesteatoma of less than 4 mm. Rates for sensitivity, specificity, and positive and negative predictive values are presented.
Decisions on whether or not to operate for cholesteatoma cannot be made based on the two imaging sequences assessed, as evaluated in this study. Other contributing factors are discussed, such as the radiological learning curve and technical limitations of the magnetic resonance imaging equipment.
We compared the burden of illness due to a spectrum of respiratory diagnostic categories among persons presenting in a sentinel general practice network in England and Wales during periods of influenza and of respiratory syncytial virus (RSV) activity. During all periods of viral activity, incidence rates of influenza-like illness, bronchitis and common cold were elevated compared to those in baseline periods. Excess rates per 100 000 of acute bronchitis were greater in children aged <1 year (median difference 2702, 95% CI 929–4867) and in children aged 1–4 years (994, 95% CI 338–1747) during RSV active periods rather than influenza; estimates for the two viruses were similar in other age groups. Excess rates of influenza-like illness in all age groups were clearly associated with influenza virus activity. For common cold the estimates of median excess rates were significantly higher in RSV active periods for the age groups <1 year (3728, 95% CI 632–5867) and 5–14 years (339, 95% CI 59–768); estimates were similar in other age groups for the two viruses. The clinical burden of disease associated with RSV is as great if not greater than influenza in patients of all ages presenting to general practitioners.
We aimed to describe the incidence of new episodes of molluscum contagiosum, scabies and lichen planus presenting to general practitioners in England and Wales. We examined data collected in a sentinel practice network (the Weekly Returns Service of the Royal College of General Practitioners) in which about half a million persons were observed each year over the period 1994–2003. The incidence of molluscum contagiosum in males was 243/100000 person-years and in females 231; of scabies, males 351, females 437; of lichen planus, males 32, females 37. Incidence varied by year and age. Ninety per cent of molluscum contagiosum episodes were reported in children aged 0–14 years, where incidence in 2000 (midpoint of a 6-year period of stable incidence) was 1265/100000 (95% CI 1240–1290). Scabies affected all ages and annual incidence ranged between 233 (95% CI 220–246) in 2003 and 470 (95% CI 452–488) in 2000. Lichen planus occurred chiefly in persons aged over 45 years: incidence (all ages) ranged between 27 (95% CI 23–31) in 2003 and 43 (95% CI 37–49) in 1998. The relative risk of female to male incidence (all ages) of molluscum contagiosum was 0·95 (95% CI 0·91–0·99); of scabies 1·25 (95% CI 1·21–1·28); and of lichen planus 1·19 (95% CI 1·08–1·13).
Three sources of data (general practice episode data from the Weekly Returns Service of the Royal College of General Practitioners, national hospital admission data for England and national mortality data by date of death) were examined separately in each winter (1994/1995 to 1999/2000) to investigate the impact of influenza on circulatory disease. Weekly data on incidence (clinical new episodes) hospital emergency admissions and deaths certified to circulatory disorders and to respiratory diseases (chapters VII and VIII of ICD9) during influenza epidemic periods (defined from combined clinical/virological surveillance) were examined in age groups 45–64, 65–74 and [ges ]75 years. Data collected in the four winters in which there were substantial influenza A epidemics were consolidated for the period 6 weeks before to 6 weeks after each peak of the epidemic, and associations between the variables at different time lags examined by calculating cross-correlation coefficients. We also examined deaths due to ischaemic heart disease (IHD) as a proportion of all circulatory deaths and deaths due to influenza/pneumonia as a proportion of all respiratory deaths. There were no increases of GP episodes nor of emergency admissions for circulatory disorders in any of the three age groups during epidemic periods. Increased circulatory deaths occurred in all age groups and particularly in the oldest group. The large cross-correlation coefficients of deaths (circulatory and respiratory) with GP respiratory episodes at weekly lags of 0, −1 and 1 were evidence that the deaths and episode distributions were contemporaneous. The ratios of excess circulatory deaths relative to excess respiratory deaths during epidemic periods were 0·74 (age 45–64), 0·72 (65–74) and 0·57 ([ges ]75 years). Increased circulatory deaths contemporary with new incident cases of respiratory episodes but with no concomitant increase in admissions suggests rapid death during the acute phase of illness. Influenza contingency planning needs to take account of these deaths in determining policy for prophylaxis and in providing facilities for cardio-respiratory resuscitation.
We investigated age- and gender-specific incidence of shingles reported in a large sentinel practice network monitoring a defined population over the years 1994–2001. In total, 5915 male and 8617 female incident cases were studied. For each age group, we calculated the relative risk of females to males presenting with shingles. Incidence rates of chickenpox and herpes simplex were examined similarly. Shingles incidence was greater in females in each age group (except for 15–24 years). Relative risks (female to male) were greatest in age groups 45–64 years (1·48) and 0–14 years (1·43). There were no gender differences in the incidence of chickenpox except in the 15–24 years age group (female excess): for herpes simplex there were female excesses in all age groups. Gender-specific age-standardized incidence rates of shingles were calculated for each year and showed a consistent female excess in each of the 8 years (average annual excess 28%).
This paper presents the results of a research project that investigated the potential benefits
of a combined Galileo/GPS navigation system. The research addressed in detail the two key
required navigation performance (RNP) parameters of accuracy and integrity. The project
was supported by Alcatel Space and was a contribution to the Galileo definition studies
(supported by the European Community under the GALA project). The results show
significant improvements in both accuracy and integrity (achievable through RAIM) when
a combined constellation is used rather than Galileo alone.
The aim of this study was to examine the haemodynamic response to seizures in three infants with Sturge–Weber syndrome by measuring regional cerebral blood flow using transcranial Doppler sonography and 99mTc HMPAO SPECT. Time-locked video/digital EEG recording was carried out for ictal studies. MRI was performed in all subjects. SPECT showed hemispheric hypoperfusion interictally in all three patients and also ictally in one of the three; a small region of hyperperfusion was seen on the same ictal scan in the latter, ie. the patient with interictal and ictal hypoperfusion. In the two older children middle cerebral artery velocity (MCAV) was reduced by between 29 and 62% in the middle cerebral artery of the predominantly affected hemisphere compared with the contralateral side. During seizures, increases of 6 to 30% in MCAV were recorded for the clinically seizing hemisphere compared with 24 to 170% for the contralateral side in four of the seizures recorded. In one infant, MCAV fell bilaterally during a seizure that generalized (−18 and −43% in the predominantly affected and contralateral side respectively). Sequential recordings in one infant suggested that, with time, the haemodynamic response to seizures of the unaffected hemisphere may decrease. These findings suggest that the venous malformation in SWS is associated with an impairment of the cerebral haemodynamic response to seizure activity.
Thirty-two adult females who consulted a general practitioner with psychiatric training were assessed by questionnaires on first attendance and at follow-up 6 months later. Major life events and the degree of social support were of importance. Failure to improve was associated with major negative life events; in the absence of such events, improvement seemed likely to occur given a high degree of social Support; major positive events appeared to be associated with improvement, regardless of the degree of social interaction. These factors, and the initial and final GHQ scores, are inter-related in a complex manner and it is suggested that these findings merit further investigation on a larger sample of patients.
The future of the psychiatric services, in particular of the mental hospital, has been the source of much speculation since the publication of the Hospital Plan for England and Wales (1962). According to the Plan there would, by 1975, be psychiatric accommodation in each Region at the level of 1·;8 beds per 1,000 population, as estimated by Tooth and Brooke (1961).
A statistical study of large numbers of chronic mental patients may seem to have no direct bearing on the problem of how to treat the individual patient and prevent chronicity. Yet the collection and analysis of mass data form an essential part of epidemiological studies which have made possible many notable advances in preventive medicine. Much of the statistical information at present available in various official documents such as the annual reports of the Ministry of Health and the Board of Control, the Registrar-General's Statistical Review, are so generalized and fragmentary as to be almost meaningless (Lancet, 1955). A few mental hospitals publish annual reports containing broad statistical information; but the detailed facts needed for proper assessment of the size and nature of the problem and for any rational reform are almost invariably lacking. Throughout the field of psychiatry, particularly in connection with the development and effect of chronicity, the existing vital statistics are incomplete and inconclusive.
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