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The Murchison Widefield Array is a low-frequency Square Kilometre Array precursor located at the Murchison Radio-astronomy Observatory in Western Australia. Primarily designed as an imaging telescope, but with a flexible signal path, the capabilities of this telescope have recently been extended to include off-line incoherent and tied-array beam formation using recorded antenna voltages. This has provided the capability for high-time and frequency resolution observations, including a pulsar science program. This paper describes the algorithms and pipeline that we have developed to form the tied-array beam products from the summation of calibrated signals of the antenna elements, and presents example polarimetric profiles for PSRs J0437-4715 and J1900-2600 at 185 MHz.
To review the literature regarding screening for vestibular schwannoma in the context of demographic changes leading to increasing numbers of elderly patients presenting with asymmetric auditory symptoms.
A systematic review of the literature was performed, with narrative synthesis and statistical analysis of data where appropriate.
Vestibular schwannomas diagnosed in patients aged over 70 years exhibit slower growth patterns and tend to be of smaller size compared to those tumours in younger age groups. This fact, combined with reduced life expectancy, renders the probability of these tumours in the elderly requiring active treatment with surgery or stereotactic radiotherapy to be extremely low. Vestibular schwannomas in the elderly are much more likely to be managed by serial monitoring with magnetic resonance imaging. The weighted yield of magnetic resonance imaging in the diagnosis of vestibular schwannoma in all age groups is 1.18 per cent, with almost 85 scans required to diagnose 1 tumour.
An evidence-based approach to the investigation of asymmetric hearing loss and tinnitus in the elderly patient can be used to formulate guidelines for the rational use of magnetic resonance imaging in this population.
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.
After five positive randomized controlled trials showed benefit of mechanical thrombectomy in the management of acute ischemic stroke with emergent large-vessel occlusion, a multi-society meeting was organized during the 17th Congress of the World Federation of Interventional and Therapeutic Neuroradiology in October 2017 in Budapest, Hungary. This multi-society meeting was dedicated to establish standards of practice in acute ischemic stroke intervention aiming for a consensus on the minimum requirements for centers providing such treatment. In an ideal situation, all patients would be treated at a center offering a full spectrum of neuroendovascular care (a level 1 center). However, for geographical reasons, some patients are unable to reach such a center in a reasonable period of time. With this in mind, the group paid special attention to define recommendations on the prerequisites of organizing stroke centers providing medical thrombectomy for acute ischemic stroke, but not for other neurovascular diseases (level 2 centers). Finally, some centers will have a stroke unit and offer intravenous thrombolysis, but not any endovascular stroke therapy (level 3 centers). Together, these level 1, 2, and 3 centers form a complete stroke system of care. The multi-society group provides recommendations and a framework for the development of medical thrombectomy services worldwide.
A computerized systetn, consisting of a fluorescence x-ray source (Philips), an Si (Li) detector (Ortec), and a mini Computer (Xerox) is currentiy in operation at The University of Texas M. D. Anderson Hospital and Tumor Institute, Experimentel Pathology Section, for the analysis of trace elements in biological specimens. The elements of interest are Fe, Cu, and Zn for possible significance in the detection and study of cancer. The detection system is being used for comparatively routine analysis of these elements, which are present in blood serum in the ppM range. With appropriate sample preparation techniques, using 1 ml of serum, the limit of detectability for these elements is estimated to be 100 ppB (1 in 107). Further refinement is possible, and research in this direction continues.
Essential variables to consider for an efficient control strategy for invasive plants include dispersion pattern (i.e., satellite or invasion front) and patch expansion rate. These variables were demonstrated for buffelgrass [Pennisetum ciliare (L.) Link], a C4 perennial grass introduced from Africa, which has invaded broadly around the world. The study site was along a roadway in southern Arizona (USA). The P. ciliare plant distributions show the pattern of clumping associated with the satellite (nascent foci) colonization pattern (average nearest neighbor test, z-score −47.2, P<0.01). The distance between patches ranged from 0.743 to 12.8 km, with an average distance between patches of 5.6 km. Median patch expansion rate was 271% over the 3-yr monitoring period versus 136% found in other studies of established P. ciliare patches. Targeting P. ciliare satellite patches as a control strategy may exponentially reduce the areal doubling time, while targeting the largest patches may have less effect on the invasion speed.
Many believe that global capital markets will generate lower returns in the future versus the past. We examine how persistently lower real returns will reshape work, retirement, saving, and investment behavior of older persons using a calibrated dynamic life cycle model. In a low return regime, workers build up less wealth in their tax-qualified 401(k) accounts versus the past, claim social security benefits later, and work more. Moreover, the better-educated are more sensitive to real interest rate changes, while the least-educated alter their behavior less. Interestingly, the distribution of wealth is more uniform in periods of persistent low expected returns.
Two competing explanations for why consumers have trouble with financial decisions are gaining momentum. One is that people are financially illiterate since they lack understanding of simple economic concepts and cannot carry out computations such as computing compound interest, which could cause them to make suboptimal financial decisions. A second is that impatience or present-bias might explain suboptimal financial decisions. That is, some people persistently choose immediate gratification instead of taking advantage of larger long-term payoffs. We use experimental evidence from Chile to explore how these factors appear related to poor financial decisions. Our results show that our measure of impatience is a strong predictor of wealth and investment in health. Financial literacy is also correlated with wealth though it appears to be a weaker predictor of sensitivity to framing in investment decisions. Policymakers interested in enhancing retirement well-being would do well to consider the importance of both factors.
Introduction: The ECG diagnosis of acute coronary occlusion (ACO) in the setting of ventricular paced rhythm (VPR) is purported to be impossible. However, VPR has a similar ECG morphology to LBBB. The validated Smith-modified Sgarbossa criteria (MSC) have high sensitivity (Sens) and specificity (Spec) for ACO in LBBB. MSC consist of 1 of the following in 1 lead: concordant ST Elevation (STE) 1 mm, concordant ST depression 1 mm in V1-V3, or ST/S ratio <−0.25 (in leads with 1 mm STE). We hypothesized that the MSC will have higher Sens for diagnosis of ACO in VPR when compared to the original Sgarbossa criteria. We report preliminary findings of the Paced Electrocardiogram Requiring Fast Emergency Coronary Therapy (PERFECT) study Methods: The PERFECT study is a retrospective, multicenter, international investigation of ED patients from 1/2008 - 12/2016 with VPR on the ECG and symptoms suggestive of acute coronary syndrome (e.g. chest pain or shortness of breath). Data from four sites are presented. Acute myocardial infarction (AMI) was defined by the Third Universal Definition of AMI. A blinded cardiologist adjudicated ACO, defined as thrombolysis in myocardial infarction score 0 or 1 on coronary angiography; a pre-defined subgroup of ACO patients with peak cardiac troponin (cTn) >100 times the 99% upper reference limit (URL) of the cTn assay was also analyzed. Another blinded physician measured all ECGs. Statistics were by Mann Whitney U, Chi-square, and McNemars test. Results: The ACO and No-AMI groups consisted of 15 and 79 encounters, respectively. For the ACO and No-AMI groups, median age was 78 [IQR 72-82] vs. 70 [61-75] and 13 (86%) vs. 48 (61%) patients were male. The median peak cTn ratio (cTn/URL) was 260 [33-663] and 0.5 [0-1.3] for ACO vs. no-AMI. The Sens and Spec for the MSC and the original Sgarbossa criteria were 67% (95%CI 39-87) vs. 46% (22-72; p=0.25) and 99% (92-100) vs. 99% (92-100; p=0.5). In pre-defined subgroup analysis of ACO patients with peak cTn >100 times the URL (n=10), the Sens was 90% (54-100) for the MSC vs. 60% (27- 86) for original Sgarbossa criteria (p=0.25). Conclusion: ACO in VPR is an uncommon condition. The MSC showed good Sens for diagnosis of ACO in the presence of VPR, especially among patients with high peak cTn, and Spec was excellent. These methods and results are consistent with studies that have used the MSC to diagnose ACO in LBBB.
Many women experience both vasomotor menopausal symptoms (VMS) and depressed mood at midlife, but little is known regarding the prospective bi-directional relationships between VMS and depressed mood and the role of sleep difficulties in both directions.
A pooled analysis was conducted using data from 21 312 women (median: 50 years, interquartile range 49−51) in eight studies from the InterLACE consortium. The degree of VMS, sleep difficulties, and depressed mood was self-reported and categorised as never, rarely, sometimes, and often (if reporting frequency) or never, mild, moderate, and severe (if reporting severity). Multivariable logistic regression models were used to examine the bi-directional associations adjusted for within-study correlation.
At baseline, the prevalence of VMS (40%, range 13–62%) and depressed mood (26%, 8–41%) varied substantially across studies, and a strong dose-dependent association between VMS and likelihood of depressed mood was found. Over 3 years of follow-up, women with often/severe VMS at baseline were more likely to have subsequent depressed mood compared with those without VMS (odds ratios (OR) 1.56, 1.27–1.92). Women with often/severe depressed mood at baseline were also more likely to have subsequent VMS than those without depressed mood (OR 1.89, 1.47–2.44). With further adjustment for the degree of sleep difficulties at baseline, the OR of having a subsequent depressed mood associated with often/severe VMS was attenuated and no longer significant (OR 1.13, 0.90–1.40). Conversely, often/severe depressed mood remained significantly associated with subsequent VMS (OR 1.80, 1.38–2.34).
Difficulty in sleeping largely explained the relationship between VMS and subsequent depressed mood, but it had little impact on the relationship between depressed mood and subsequent VMS.
The appeal of ketamine – in promptly ameliorating depressive symptoms even in those with non-response – has led to a dramatic increase in its off-label use. Initial promising results await robust corroboration and key questions remain, particularly concerning its long-term administration. It is, therefore, timely to review the opinions of mood disorder experts worldwide pertaining to ketamine's potential as an option for treating depression and provide a synthesis of perspectives – derived from evidence and clinical experience – and to consider strategies for future investigations.
The growth and popularity of defined contribution pensions, along with the government's increasing attention to retirement plan costs and investment choices provided, make it important to understand how people select their retirement plan investments. This paper shows how employees in a large firm altered their fund allocations when the employer streamlined its pension fund menu and deleted nearly half of the offered funds. Using administrative data, we examine the changes in plan participant investment choices that resulted from the streamlining and how these changes might affect participants’ eventual retirement wellbeing. We show that streamlined participants’ new allocations exhibited significantly lower within-fund turnover rates and expense ratios, and we estimate this could lead to aggregate savings for these participants over a 20-year period of $20.2 M, or in excess of $9,400 per participant. Moreover, after the reform, streamlined participants’ portfolios held significantly less equity and exhibited significantly lower risks by way of reduced exposures to most systematic risk factors, compared with their non-streamlined counterparts.
Hedonic modeling of Oklahoma cow auction data is used to determine the market value of bred cow characteristics. We use Agricultural Marketing Service data that let us consider more years and more lots of cattle than is typical for a cattle hedonic study. The greatest price premiums were for black, late-gestating cows, categorized as high quality by market reporters and weighing between 1,600 and 1,700 lb. Previous research on optimal cow size finds much smaller-size cows are optimal, and our research finds that larger cows receive a lower price per pound but still receive a substantially higher price per head.
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 Crab pulsar was first detected soon after the discovery of pulsars, and has long been studied for its unique traits. One of these traits, giant pulses that can be upwards of 1000 times brighter than the average pulse, was key to the Crab’s initial detection. Giant pulses are only seen in a few pulsars, and their energy distributions distinguish them from normal pulsed emission. There have been many studies over a period of decades to measure the power-law slope of these energy distributions, which provide insight into the possible emission mechanism of these giant pulses.
The 42-foot telescope at Jodrell Bank Observatory monitors the Crab pulsar on a daily basis. We have single-pulse data dating back to 2012, containing roughly 1,000,000 giant pulses, the largest sample of Crab giant pulses to date. This large set of giant pulses allows us to do a range of science, including pulse-width studies and in-depth studies of giant-pulse energy distributions. The latter are particularly interesting, as close inspection of the high-energy tail of the energy distribution allows us to investigate the detectability of extragalactic giant-pulsing pulsars. Also, by calculating rates from these energy distributions, we may be able to shed light on a possible link between Fast Radio Bursts and giant pulses.