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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.
Infrared absorption spectroscopy is a powerful tool for structural and functional studies of biomolecules. The technique enables direct access to the vibrational fingerprints of molecular bonds in the mid-infrared spectral region (3-20μm). Although intrinsic absorption cross-sections are nearly ten orders of magnitude greater than corresponding Raman cross-sections, they are still small in comparison with those of fluorescent molecules. Sensitivity improvements are therefore required for the method to be applicable to single molecule / molecular layer studies. In this work, we demonstrate the use of lithographically patterned arrays of nanoantennas to enhance the absorption signature of the protein amide-I and II backbone vibrations. Strong absorption signals from monolayer thickness films are obtained. By arranging ensembles of tailored antennas in specific lattices, higher quality factor resonances and increased near-field intensities are possible. These features are leveraged to obtain 104-105 fold signal enhancements and the direct measurement of vibrational spectra of proteins at zepto-mole sensitivity levels.
X-ray diffraction is one of the most useful methods for the characterisation of thin crystalline layers or coatings. The most interesting techniques are: the identification of phases and their relative quantities, texture analysis, and residual stress measurements.
Thin layers which are transparent to the x-ray beam (in the diffracted wavelength) yield different intensities as compared with a bulk sample.
The smr and qacA/B genes in Staphylococcus aureus confer tolerance to antiseptics and are associated with nosocomial acquisition of infection and underlying medical conditions. Such antiseptic tolerance (AT) genes have also been reported in coagulase-negative staphylococci (CoNS) and enterococci, however, few data are available regarding their prevalence. We sought to describe the frequency of AT genes among bloodstream isolates of S. aureus, CoNS and enterococci at Texas Children’s Hospital (TCH).
Banked CoNS, S. aureus and enterococci isolated from blood cultures collected bewteen October 1, 2016, and October 1, 2017, were obtained from the TCH clinical microbiology laboratory. All isolates underwent polymerase chain reaction (PCR) assay for the qacA/B and smr genes. Medical records were reviewed for all cases.
In total, 103 CoNS, 19 Enterococcus spp, and 119 S. aureus isolates were included in the study, and 80.6% of the CoNS possessed at least 1 AT gene compared to 37% of S. aureus and 43.8% of E. faecalis isolates (P < .001). Among CoNS bloodstream isolates, the presence of either AT gene was strongly associated with nosocomial infection (P < .001). The AT genes in S. aureus were associated with nosocomial infection (P = .025) as well as the diagnosis of central-line–associated bloodstream infection (CLABSI; P = .04) and recent hospitalizations (P < .001). We found no correlation with genotypic AT in E. faecalis and any clinical variable we examined.
Antiseptic tolerance is common among bloodstream staphylococci and E. faecalis isolates at TCH. Among CoNS, the presence of AT genes is strongly correlated with nosocomial acquisition of infection, consistent with previous studies in S. aureus. These data suggest that the healthcare environment contributes to AT among staphylococci.
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.
Adverse childhood experiences (ACEs) of parents are associated with a variety of negative health outcomes in offspring. Little is known about the mechanisms by which ACEs are transmitted to the next generation. Given that maternal depression and anxiety are related to ACEs and negatively affect children’s behaviour, these exposures may be pathways between maternal ACEs and child psychopathology. Child sex may modify these associations. Our objectives were to determine: (1) the association between ACEs and children’s behaviour, (2) whether maternal symptoms of prenatal and postnatal depression and anxiety mediate the relationship between maternal ACEs and children’s behaviour, and (3) whether these relationships are moderated by child sex. Pearson correlations and latent path analyses were undertaken using data from 907 children and their mothers enrolled the Alberta Pregnancy Outcomes and Nutrition study. Overall, maternal ACEs were associated with symptoms of anxiety and depression during the perinatal period, and externalizing problems in children. Furthermore, we observed indirect associations between maternal ACEs and children’s internalizing and externalizing problems via maternal anxiety and depression. Sex differences were observed, with boys demonstrating greater vulnerability to the indirect effects of maternal ACEs via both anxiety and depression. Findings suggest that maternal mental health may be a mechanism by which maternal early life adversity is transmitted to children, especially boys. Further research is needed to determine if targeted interventions with women who have both high ACEs and mental health problems can prevent or ameliorate the effects of ACEs on children’s behavioural psychopathology.
Introduction: Upper gastrointestinal bleeding (UGIB) is a common medical condition presenting to emergency departments (ED) and associated with substantial morbidity, mortality, and healthcare expenditures. Our aim was to evaluate the incidence of patients presenting to ED with UGIB in a large population-based surveillance cohort. Methods: The National Ambulatory Care Reporting System (NACRS) was used to identify all presentations to emergency departments for UGIB in Alberta from fiscal year 2010 to 2015 (n=56519) using the International Classification of Diseases Codes (ICD-10) in any diagnostic position. Baseline characteristics and UGIB incidence were calculated using descriptive statistics. Joinpoint regression models were used to calculate the average annual percent change (AAPC) with 95% confidence intervals (CI). Results: The median age of 56519 UGIB presentations was 56 years (interquartile range: 41 to 74 years), 56% were male, and 245% had at least one comorbidity. At time of disposition from the ED , 48.3% were admitted to or transferred to another hospital, 51.4% discharged, and 0.3% died in the emergency department. Further, 10.8% underwent upper endoscopy during their admission to the emergency department. The annual incidence of UGIB were 230.6 (2010), 232.8 (2011), 241.0 (2012), 242.2 (2013), 244.6 (2014), and 242.2 (2015) per 100,000 person-years. Between 2010 and 2015 the incidence of UGIB presenting to ED significantly increased overtime (AAPC=1.1; 95% CI: 0.3 to 2.0). Conclusion: UGIB is a common presentation to emergency departments and has been increasing overtime. Future studies are necessary to evaluate the underlying cause of UGIB and to determine its burden to Albertas healthcare system.
Introduction: Non-variceal upper gastrointestinal bleeding (NVUGIB) is a common presentation to the emergency department (ED) accounting for significant morbidity, mortality and health care resource usage. In Alberta, a provincial care pathway was recently developed to provide an evidence informed approach to managing patients with an UGIBs in the ED. Pantoprazole infusions are a commonly used treatment despite evidence that suggests they are generally not indicated prior to endoscopy in the ED. The goal of this project was to optimize management of patients with a NVUGIB, in particular reduce pre-endoscopy pantoprazole infusions. Methods: In July 2016, we implemented a multi-faceted intervention to optimize management of ED patients with NVUGIB including 1. de-emphasizing IV pantoprazole infusions in the ED, 2. clinical decision support (CDS) embedded (for endoscopy, disposition and transfusions) within the order set and 3. educating clinicians about the care pathway. We used a pre/post-order set design, analyzing 391 days pre and 189 days post-order set changes. Data was extracted from our fully integrated electronic health records system. The primary outcome was the % of patients receiving IV pantoprazole infusion ordered by an emergency physician (EP) among all patients with NVUGIB. Secondary outcomes included % transfused with hgb >70g/L and whether using the GIB order set impacted management of NVUGIB patients. Results: In the 391 days pre-order set changes, there were 2165 patients included and in the 189 days post-order set changes, there were 901 patients. For baseline characteristics, patients in the post-order set change group were significantly older (64.4 yrs vs 60.9 yrs p-value=0.0016) and had a lower hgb (115 vs 118, p-value=0.049) but otherwise for gender, measures of severity of illness (systolic blood pressure, heart rate, CTAS, % admitted) there were no significantly differences. For the primary outcome, in the pre-order set phase, 47.1% received a pantoprazole infusion ordered by an EP, compared to 31.5% in the post-order phase, for an absolute reduction of 15.6% (p-value= <0.001). For the secondary outcomes, transfusion rates were similar pre/post (22.08% vs 22.75%). Significant inter-site variability exists with respect to the reduction in pantoprazole infusion rates across the four sites (-23.3% to +6.12%). Conclusion: Our interventions resulted in a significant overall reduction in pantoprazole infusions in ED patients with NVUGIB. Reductions in pantoprazole infusions varied significantly across the different sites, future work in our department will explore and address this variability. Keys to the success of this project included engaging clinicians as well as leveraging the SCM order sets as well as the provincial care pathway. Although there were no changes in transfusion rates, it in unclear if this a function of the CDS not being effective or whether these transfusions were clinically indicated.
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.
We present techniques developed to calibrate and correct Murchison Widefield Array low-frequency (72–300 MHz) radio observations for polarimetry. The extremely wide field-of-view, excellent instantaneous (u, v)-coverage and sensitivity to degree-scale structure that the Murchison Widefield Array provides enable instrumental calibration, removal of instrumental artefacts, and correction for ionospheric Faraday rotation through imaging techniques. With the demonstrated polarimetric capabilities of the Murchison Widefield Array, we discuss future directions for polarimetric science at low frequencies to answer outstanding questions relating to polarised source counts, source depolarisation, pulsar science, low-mass stars, exoplanets, the nature of the interstellar and intergalactic media, and the solar environment.
The weak thermal emission from the largest minor planets can be detected in the microwave regime by the Very Large Array (VLA). Signal-to-noise ratios are sufficiently high to permit precise measurement of the positions of these objects at all points in their orbits with respect to background extragalactic sources. We are in the process of obtaining observations of astrometric accuracy for minor planets 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygeia.
Minor planets have historically served as “test particles” in the solar system, and optical observations of these objects have been valuable in the determination of fundamental astronomical constants. In particular, optical observations of minor planets have played an important role in the establishment of the fundamental optical reference frame by permitting the determination of the orientation of the Earth's orbit relative to the stars defining the frame.
Similarly, radio observations of these bodies can play a corresponding role in the establishment of a fundamental radio reference frame. Our observations will provide a direct link between the dynamical and radio reference frames, and provide important information on the relationship between the radio and optical reference frames.
Considerable progress has been made over the last few years in ground based optical interferometery. The Mark III optical interferometer at Mount Wilson which at this time is operating with a 12 meter north south baseline is capable of measuring amplitude and phase. Experience gained from this facility will allow for the development of a large optical array. Preliminary plans are described for a facility that will be capable of milliarcsecond imaging of celestial objects at wavelengths from 0.4 to 10 microns. If funded this array will be in operation by 1993.
Sleep disturbances are prominent correlates of acute mood episodes and inadequate recovery in bipolar disorder (BD), yet the mechanistic relationship between sleep physiology and mood remains poorly understood. Using a series of pre-sleep mood inductions and overnight sleep recording, this study examined the relationship between overnight mood regulation and a marker of sleep intensity (non-rapid eye movement sleep slow wave activity; NREM SWA) during the interepisode phase of BD.
Adults with interepisode BD type 1 (BD; n = 20) and healthy adult controls (CTL; n = 23) slept in the laboratory for a screening night, a neutral mood induction night (baseline), a happy mood induction night, and a sad mood induction night. NREM SWA (0.75–4.75 Hz) was derived from overnight sleep EEG recordings. Overnight mood regulation was evaluated using an affect grid pleasantness rating post-mood induction (pre-sleep) and the next morning.
Overnight mood regulation did not differ between groups following the sad or happy inductions. SWA did not significantly change for either group on the sad induction night compared with baseline. In BD only, SWA on the sad night was related to impaired overnight negative mood regulation. On the happy induction night, SWA increased relative to baseline in both groups, though SWA was not related to overnight mood regulation for either group.
These findings indicate that SWA disruption may play a role in sustaining negative mood state from the previous night in interepisode BD. However, positive mood state could enhance SWA in bipolar patients and healthy adults.
Introduction: Acute non-variceal upper gastrointestinal bleeding (NVUGIB) is a common presentation to the Emergency Department (ED) associated with significant mortality and morbidity. Recent evidence suggests that overt-transfusion is associated with poor patient outcomes and that stable patients above a hemoglobin (hgb) above 70 g/L should be transfused judiciously. This retrospective health records review aims to determine the proportion of NVUGIB patients with hemoglobin greater than 70 g/L who were still appropriately transfused based on clinical parameters. Methods: A retrospective review was conducted on randomly selected patients that presented to one of two major tertiary hospitals with a primary diagnosis of NVUGIB who received blood products, despite a presenting hemoglobin >70 g/L. Standardized case report forms were developed through chart abstraction using a pilot-tested template. The appropriateness of transfusion was then adjudicated separately by a trained medical student and an emergency physician; discrepancies were resolved by discussion. Results: Following independent review of the charts, agreement was met on 94% (45/48) of the charts and after collective discussion 100% consensus was reached and all 48 patients’ transfusion appropriateness and categorized into one of three groups: Appropriate, Potentially avoidable, and clearly avoidable. Only in 22.9% (11/48) of the cases was transfusion deemed to be clearly avoidable while emergency physicians appropriately transfused 45.8% (22/48) of patients based on clinical status and other factors. In 31.3% (15/48) of the cases, transfusion was potentially avoidable in favor of other management options. We calculated the mean GBS for the appropriate, potentially avoidable, and clearly avoidable categories yielding 12.8, 12.7, and 10.2 respectively. Mortality occurred in 2 of the 48 cases (4%). Conclusion: In most instances, emergency physicians are effectively integrating hemoglobin thresholds and clinical status to determine if a patients with NVUGIB and hgb >70 require blood products.
The astrometric optical interferometer on Mt. Wilson is providing a new source of astrophysical and astrometric data on bright stars. The instrument, with 12-meter baselines, has been in operation since late 1986. The interferometer is capable of wide-angle astrometry, that is, the determination of very precise stellar positions within a reference frame defined by bright stars spread across a large area (of order one steradian) of the sky. This paper addresses the question of whether such an instrument can be used to establish a fundamental system — that is, one tied to the Earth in some well-defined way. Some astrometric data from this instrument are presented to illustrate the difficulties involved. Proposed means of addressing these problems in future instruments are discussed.
During the past three years radiocarbon assay has emerged as a primary tool in the quantitative assignment of sources of urban and rural particulate pollution. Its use in several major field studies has come about because of its excellent (fossil/biogenic) discriminating power, because of advances in 14C measurements of small samples, and because of the increased significance of carbonaceous particles in the atmosphere. The problem is especially important in the cities, where increased concentrations of fine particles lead to pollution episodes characterized by poor visibility and changes in the radiation balance (absorption, scattering), and immediate and possibly long-term health effects. Efforts in source apportionment in such affected areas have been based on emissions inventories, dispersion modeling, and receptor modeling – ie, chemical and physical (and statistical) characterization of particles collected at designated receptor sites. It is in the last category that 14C has become quite effective in helping to resolve particle sources. Results are presented for studies carried out in Los Angeles, Denver, and Houston which incorporated 14C measurements, inorganic and organic chemical characterization, and receptor modeling. The 14C data indicated wide ranging contributions of biogenic and fossil carbon sources – eg, <10% to 60% contemporary (biogenic) in Houston – depending on meteorological, biological, and anthropological activity. The combined (chemical, isotopic, statistical) data point to sources such as vehicles, wood combustion, power plants, and vegetation.
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.
The first observations by a worldwide network of advanced interferometric gravitational wave detectors offer a unique opportunity for the astronomical community. At design sensitivity, these facilities will be able to detect coalescing binary neutron stars to distances approaching 400 Mpc, and neutron star–black hole systems to 1 Gpc. Both of these sources are associated with gamma-ray bursts which are known to emit across the entire electromagnetic spectrum. Gravitational wave detections provide the opportunity for ‘multi-messenger’ observations, combining gravitational wave with electromagnetic, cosmic ray, or neutrino observations. This review provides an overview of how Australian astronomical facilities and collaborations with the gravitational wave community can contribute to this new era of discovery, via contemporaneous follow-up observations from the radio to the optical and high energy. We discuss some of the frontier discoveries that will be made possible when this new window to the Universe is opened.
The United States Naval Observatory (NAVOBSY) and the Naval Research Laboratory (NRL) are collaborating in a program to apply radio interferometric techniques to the determination of variations in Earth rotation, polar motion, and improved astronomical position reference systems. Investigations of VLBI and connected interferometer techniques and radio sources for astrometic application have been in progress for several years as part of the NRL radio astronomy program, and currently NRL and NAVOBSY are carrying out experimental programs to investigate VLBI time transfer techniques and UT determination using the connected element interferometer of the NRAO in Green Bank. Some previous results of observations using the Green Bank interferometer and proposed plans for operation as a dedicated system over a period of time to evaluate effectiveness for precise determination of Earth rotation parameters are discussed.