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We have observed the Vela pulsar for 1 year using a Phased Array Feed (PAF) receiver on the 12-m antenna of the Parkes Test-Bed Facility (PTF). These observations have allowed us to investigate the stability of the PAF beam weights over time, to demonstrate that pulsars can be timed over long periods using PAF technology and to detect and study the most recent glitch event that occurred on 12 December 2016. The beam weights are shown to be stable to 1% on time scales on the order of three weeks.
Radio continuum surveys are equally sensitive to all pulsars, not affected by dispersion measure smearing, scattering or orbital modulation of spin periods, and therefore allow us to search for extreme pulsars, such as sub-millisecond pulsars, pulsar-black hole systems and pulsars in the Galactic Centre. As we move towards the Square Kilometre Array (SKA) era, searching for pulsars in continuum images will complement conventional pulsar searches, and make it possible to find extreme objects.
PSR B1828–11 is a young pulsar once thought to be undergoing free precession and recently found instead to be switching magnetospheric states in tandem with spin-down changes. Here we show the two extreme states of the mode-changing found for this pulsar and comment briefly on its interpretation.
During 2016 February, CSIRO Astronomy and Space Science and the Max-Planck-Institute for Radio Astronomy installed, commissioned, and carried out science observations with a phased array feed receiver system on the 64-m diameter Parkes radio telescope. Here, we demonstrate that the phased array feed can be used for pulsar observations and we highlight some unique capabilities. We demonstrate that the pulse profiles obtained using the phased array feed can be calibrated and that multiple pulsars can be simultaneously observed. Significantly, we find that an intrinsic polarisation leakage of −31 dB can be achieved with a phased array feed beam offset from the centre of the field of view. We discuss the possibilities for using a phased array feed for future pulsar observations and for searching for fast radio bursts with the Parkes and Effelsberg telescopes.
With the launch of Gaia in December 2013, Europe entered a new era of space astrometry following in the footsteps of the very successful Hipparcos mission. A weakness of Gaia is that it only operates at optical wavelengths. However, much of the Galactic centre and the spiral arm regions are obscured by interstellar extinction. An obvious improvement on Gaia is to include the Near-Infra-Red (NIR) which requires the use of new types of detectors. Additionally, to scan the entire sky and measure global absolute parallaxes the spacecraft must have a constant rotation resulting in a moving image that must be compensated for by, for example, operating the detectors in Time Delayed Integration (TDI) mode. If these technical issues can be solved a new Gaia-like mission separated by a 20 year interval would give; 1) NIR all-sky astrometry and photometry to penetrate the obscured regions and to observe intrinsically red objects with almost diffraction limited resolution; 2) improved proper motions with fourteen times smaller errors than from Gaia alone opening up new science cases, such as long period exoplanets and accurate halo measurements; 3) allow the slowly degrading accuracy of the Gaia reference frame, which will be the basis for future astronomical measurements, to be reset.
Salmonella is a leading cause of bacterial foodborne illness. We report the collaborative investigative efforts of US and Canadian public health officials during the 2013–2014 international outbreak of multiple Salmonella serotype infections linked to sprouted chia seed powder. The investigation included open-ended interviews of ill persons, traceback, product testing, facility inspections, and trace forward. Ninety-four persons infected with outbreak strains from 16 states and four provinces were identified; 21% were hospitalized and none died. Fifty-four (96%) of 56 persons who consumed chia seed powder, reported 13 different brands that traced back to a single Canadian firm, distributed by four US and eight Canadian companies. Laboratory testing yielded outbreak strains from leftover and intact product. Contaminated product was recalled. Although chia seed powder is a novel outbreak vehicle, sprouted seeds are recognized as an important cause of foodborne illness; firms should follow available guidance to reduce the risk of bacterial contamination during sprouting.
Post-traumatic symptomatology is one of the signature effects of the pernicious exposures endured by responders to the World Trade Center (WTC) disaster of 11 September 2001 (9/11), but the long-term extent of diagnosed Diagnostic and Statistical Manual of Mental Disorders, 4th edition (DSM-IV) post-traumatic stress disorder (PTSD) and its impact on quality of life are unknown. This study examines the extent of DSM-IV PTSD 11–13 years after the disaster in WTC responders, its symptom profiles and trajectories, and associations of active, remitted and partial PTSD with exposures, physical health and psychosocial well-being.
Master's-level psychologists administered sections of the Structured Clinical Interview for DSM-IV and the Range of Impaired Functioning Tool to 3231 responders monitored at the Stony Brook University World Trade Center Health Program. The PTSD Checklist (PCL) and current medical symptoms were obtained at each visit.
In all, 9.7% had current, 7.9% remitted, and 5.9% partial WTC-PTSD. Among those with active PTSD, avoidance and hyperarousal symptoms were most commonly, and flashbacks least commonly, reported. Trajectories of symptom severity across monitoring visits showed a modestly increasing slope for active and decelerating slope for remitted PTSD. WTC exposures, especially death and human remains, were strongly associated with PTSD. After adjusting for exposure and critical risk factors, including hazardous drinking and co-morbid depression, PTSD was strongly associated with health and well-being, especially dissatisfaction with life.
This is the first study to demonstrate the extent and correlates of long-term DSM-IV PTSD among responders. Although most proved resilient, there remains a sizable subgroup in need of continued treatment in the second decade after 9/11.
Depressive symptoms are prominent psychopathological features of Huntington's disease (HD), making a negative impact on social functioning and well-being.
We compared the frequencies of a history of depression, previous suicide attempts and current subthreshold depression between 61 early-stage HD participants and 40 matched controls. The HD group was then split based on the overall HD group's median Hospital Anxiety and Depression Scale-depression score into a group of 30 non-depressed participants (mean 0.8, s.d. = 0.7) and a group of 31 participants with subthreshold depressive symptoms (mean 7.3, s.d. = 3.5) to explore the neuroanatomy underlying subthreshold depressive symptoms in HD using voxel-based morphometry (VBM) and diffusion tensor imaging (DTI).
Frequencies of history of depression, previous suicide attempts or current subthreshold depressive symptoms were higher in HD than in controls. The severity of current depressive symptoms was also higher in HD, but not associated with the severity of HD motor signs or disease burden. Compared with the non-depressed HD group DTI revealed lower fractional anisotropy (FA) values in the frontal cortex, anterior cingulate cortex, insula and cerebellum of the HD group with subthreshold depressive symptoms. In contrast, VBM measures were similar in both HD groups. A history of depression, the severity of HD motor signs or disease burden did not correlate with FA values of these regions.
Current subthreshold depressive symptoms in early HD are associated with microstructural changes – without concomitant brain volume loss – in brain regions known to be involved in major depressive disorder, but not those typically associated with HD pathology.
We present the first results of a dedicated search for Diffuse Interstellar Bands that have profiles with FWHM > 6 Å. Broad DIBs have been noticed in past surveys using averages of multiple sight lines (e.g. Jenniskens & Désert, 1994), but careful detection, measurement, and cataloguing for individual sight lines has not been done since the pioneering work of Herbig (1995). We have initiated an observing campaign using the Apache Point Observatory in order to obtain low-resolution spectra to search for such broad DIBs and monitor their behaviour from star to star. A first sample of 21 stars with 0.3 < E(B-V) < 3.3 mag, along with 15 matched low-reddening stars, were observed with the APO/DIS B400 (R ~ 450) and R300 (R ~ 1000) gratings to obtain spectra having S/N > 500.
Anomalously broad diffuse interstellar bands (DIBs) at 5780.5, 5797.1, 6196.0, and 6613.6 Å are found in absorption along the line of sight to Herschel 36, an O star system next to the bright Hourglass nebula of the Hii region Messier 8. Excited lines of CH and CH+ are seen as well. We show that the region is very compact and itemize other anomalies of the gas. An infrared-bright star within 400 AU is noted. The combination of these effects produces anomalous DIBs, interpreted by Oka et al. (2013, see also this volume) as being caused predominantly by infrared pumping of rotational levels of relatively small molecules.
The first direct detection of gravitational waves may be made through observations of pulsars. The principal aim of pulsar timing-array projects being carried out worldwide is to detect ultra-low frequency gravitational waves (f ∼ 10−9–10−8 Hz). Such waves are expected to be caused by coalescing supermassive binary black holes in the cores of merged galaxies. It is also possible that a detectable signal could have been produced in the inflationary era or by cosmic strings. In this paper, we review the current status of the Parkes Pulsar Timing Array project (the only such project in the Southern hemisphere) and compare the pulsar timing technique with other forms of gravitational-wave detection such as ground- and space-based interferometer systems.
The future of centimetre and metre-wave astronomy lies with the Square Kilometre Array (SKA), a telescope under development by a consortium of 17 countries that will be 50 times more sensitive than any existing radio facility. Most of the key science for the SKA will be addressed through large-area imaging of the Universe at frequencies from a few hundred MHz to a few GHz. The Australian SKA Pathfinder (ASKAP) is a technology demonstrator aimed in the mid-frequency range, and achieves instantaneous wide-area imaging through the development and deployment of phased-array feed systems on parabolic reflectors. The large field-of-view makes ASKAP an unprecedented synoptic telescope that will make substantial advances in SKA key science. ASKAP will be located at the Murchison Radio Observatory in inland Western Australia, one of the most radio-quiet locations on the Earth and one of two sites selected by the international community as a potential location for the SKA. In this paper, we outline an ambitious science program for ASKAP, examining key science such as understanding the evolution, formation and population of galaxies including our own, understanding the magnetic Universe, revealing the transient radio sky and searching for gravitational waves.
A ‘pulsar timing array’ (PTA), in which observations of a large sample of pulsars spread across the celestial sphere are combined, allows investigation of ‘global’ phenomena such as a background of gravitational waves or instabilities in atomic timescales that produce correlated timing residuals in the pulsars of the array. The Parkes Pulsar Timing Array (PPTA) is an implementation of the PTA concept based on observations with the Parkes 64-m radio telescope. A sample of 20 ms pulsars is being observed at three radio-frequency bands, 50 cm (~700 MHz), 20 cm (~1400 MHz), and 10 cm (~3100 MHz), with observations at intervals of two to three weeks. Regular observations commenced in early 2005. This paper describes the systems used for the PPTA observations and data processing, including calibration and timing analysis. The strategy behind the choice of pulsars, observing parameters, and analysis methods is discussed. Results are presented for PPTA data in the three bands taken between 2005 March and 2011 March. For 10 of the 20 pulsars, rms timing residuals are less than 1 μs for the best band after fitting for pulse frequency and its first time derivative. Significant ‘red’ timing noise is detected in about half of the sample. We discuss the implications of these results on future projects including the International Pulsar Timing Array and a PTA based on the Square Kilometre Array. We also present an ‘extended PPTA’ data set that combines PPTA data with earlier Parkes timing data for these pulsars.
We report here on two years of timing of 168 pulsars using the Parkes radio telescope. The vast majority of these pulsars have spin-down luminosities in excess of 1034 erg s−1 and are prime target candidates to be detected in gamma-rays by the Fermi Gamma-Ray Space Telescope. We provide the ephemerides for the ten pulsars being timed at Parkes which have been detected by Fermi in its first year of operation. These ephemerides, in conjunction with the publicly available photonlist, can be used to generate gamma-ray profiles from the Fermi archive. We will make the ephemerides of any pulsars of interest available to the community upon request. In addition to the timing ephemerides, we present the parameters for 14 glitches which have occurred in 13 pulsars, seven of which have no previously known glitch history.The Parkes timing programme, in conjunction with Fermi observations, is expected to continue for at least the next four years.
Proton radiography using laser-driven sources has been developed as a diagnostic since the beginning of the decade, and applied successfully to a range of experimental situations. Multi-MeV protons driven from thin foils via the Target Normal Sheath Acceleration mechanism, offer, under optimal conditions, the possibility of probing laser-plasma interactions, and detecting electric and magnetic fields as well as plasma density gradients with ~ps temporal resolution and ~ 5–10 µm spatial resolution. In view of these advantages, the use of proton radiography as a diagnostic in experiments of relevance to Inertial Confinement Fusion is currently considered in the main fusion laboratories. This paper will discuss recent advances in the application of laser-driven radiography to experiments of relevance to Inertial Confinement Fusion. In particular we will discuss radiography of hohlraum and gasbag targets following the interaction of intense ns pulses. These experiments were carried out at the HELEN laser facility at AWE (UK), and proved the suitability of this diagnostic for studying, with unprecedented detail, laser-plasma interaction mechanisms of high relevance to Inertial Confinement Fusion. Non-linear solitary structures of relevance to space physics, namely phase space electron holes, have also been highlighted by the measurements. These measurements are discussed and compared to existing models.
An outbreak of keratoconjunctivitis is described which involved at least 186 people; adenovirus type 8 was identified in 50 of the cases. Topical human fibroblast interferon was assessed in a double-blind, placebo-controlled study in which 34 patients participated. Seventeen of the 34 trial patients yielded adenovirus type 8; three were infected with adenovirus type 7. The outbreak was curtailed by control of infection measures: principally careful hand-washing by medical personnel between cases and by discouraging attendance of new cases at the Eye Infirmary. Consequently the trial numbers are small. In addition there was a wide interpatient variation in the severity of infection. Therefore it was not possible to make any statistically valid conclusions concerning the recovery rate of patients receiving interferon or placebo.
The extant major psychiatric classifications, DSM-IV and ICD-10, are purportedly atheoretical and largely descriptive. Although this achieves good reliability, the validity of a medical diagnosis is greatly enhanced by an understanding of both risk factors and clinical history. In an effort to group mental disorders on the basis of risk factors and clinical manifestations, five clusters have been proposed. The purpose of this paper is to consider the position of bipolar disorder (BPD), which could be either with the psychoses, or with emotional disorders, or in a separate cluster.
We reviewed the literature on BPD, unipolar depression (UPD) and schizophrenia in relation to 11 validating criteria proposed by the DSM-V Task Force Study Group, and then summarized similarities and differences between BPD and schizophrenia on the one hand, and UPD on the other.
There are differences, often substantial and never trivial, for 10 of the 11 validators between BPD and UPD. There are also important differences between BPD and schizophrenia.
BPD has previously been classified together with UPD, but this is the least justifiable place for it. If it is to be recruited to a ‘psychotic cluster’, there are several important respects in which it differs from schizophrenia, so the cluster would have a division within it. The alternative would be to allow it to be in an intermediate position in a cluster of its own.
The extant major psychiatric classifications DSM-IV, and ICD-10, are atheoretical and largely descriptive. Although this achieves good reliability, the validity of a medical diagnosis would be greatly enhanced by an understanding of risk factors and clinical manifestations. In an effort to group mental disorders on the basis of aetiology, five clusters have been proposed. This paper considers the validity of the fourth cluster, emotional disorders, within that proposal.
We reviewed the literature in relation to 11 validating criteria proposed by a Study Group of the DSM-V Task Force, as applied to the cluster of emotional disorders.
An emotional cluster of disorders identified using the 11 validators is feasible. Negative affectivity is the defining feature of the emotional cluster. Although there are differences between disorders in the remaining validating criteria, there are similarities that support the feasibility of an emotional cluster. Strong intra-cluster co-morbidity may reflect the action of common risk factors and also shared higher-order symptom dimensions in these emotional disorders.
Emotional disorders meet many of the salient criteria proposed by the Study Group of the DSM-V Task Force to suggest a classification cluster.
In an effort to group mental disorders on the basis of aetiology, five clusters have been proposed. In this paper, we consider the validity of the first cluster, neurocognitive disorders, within this proposal. These disorders are categorized as ‘Dementia, Delirium, and Amnestic and Other Cognitive Disorders’ in DSM-IV and ‘Organic, including Symptomatic Mental Disorders’ in ICD-10.
We reviewed the literature in relation to 11 validating criteria proposed by a Study Group of the DSM-V Task Force as applied to the cluster of neurocognitive disorders.
‘Neurocognitive’ replaces the previous terms ‘cognitive’ and ‘organic’ used in DSM-IV and ICD-10 respectively as the descriptor for disorders in this cluster. Although cognitive/organic problems are present in other disorders, this cluster distinguishes itself by the demonstrable neural substrate abnormalities and the salience of cognitive symptoms and deficits. Shared biomarkers, co-morbidity and course offer less persuasive evidence for a valid cluster of neurocognitive disorders. The occurrence of these disorders subsequent to normal brain development sets this cluster apart from neurodevelopmental disorders. The aetiology of the disorders is varied, but the neurobiological underpinnings are better understood than for mental disorders in any other cluster.
Neurocognitive disorders meet some of the salient criteria proposed by the Study Group of the DSM-V Task Force to suggest a classification cluster. Further developments in the aetiopathogenesis of these disorders will enhance the clinical utility of this cluster.