To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure email@example.com
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Investors may underdiversify their portfolios by overweighting securities in which they perceive an informational advantage or by underweighting securities to hedge risks outside the portfolio. We investigate underdiversification in institutional portfolio construction by examining the under/overweighting of industries in U.S. property–liability (PL) insurers’ equity portfolios. We find that PL insurers underweight both their own industry and highly correlated industries in their portfolios. This underweighting is larger for PL insurers exposed to higher underwriting risk. Although PL insurers have an informational advantage in investing in their peers, their underwriting risk drives them to underweight stocks in their industry.
Compulsory admission procedures of patients with mental disorders vary between countries in Europe. The Ethics Committee of the European Psychiatric Association (EPA) launched a survey on involuntary admission procedures of patients with mental disorders in 40 countries to gather information from all National Psychiatric Associations that are members of the EPA to develop recommendations for improving involuntary admission processes and promote voluntary care.
The survey focused on legislation of involuntary admissions and key actors involved in the admission procedure as well as most common reasons for involuntary admissions.
We analyzed the survey categorical data in themes, which highlight that both medical and legal actors are involved in involuntary admission procedures.
We conclude that legal reasons for compulsory admission should be reworded in order to remove stigmatization of the patient, that raising awareness about involuntary admission procedures and patient rights with both patients and family advocacy groups is paramount, that communication about procedures should be widely available in lay-language for the general population, and that training sessions and guidance should be available for legal and medical practitioners. Finally, people working in the field need to be constantly aware about the ethical challenges surrounding compulsory admissions.
The Murchison Widefield Array (MWA) is an open access telescope dedicated to studying the low-frequency (80–300 MHz) southern sky. Since beginning operations in mid-2013, the MWA has opened a new observational window in the southern hemisphere enabling many science areas. The driving science objectives of the original design were to observe 21 cm radiation from the Epoch of Reionisation (EoR), explore the radio time domain, perform Galactic and extragalactic surveys, and monitor solar, heliospheric, and ionospheric phenomena. All together
programs recorded 20 000 h producing 146 papers to date. In 2016, the telescope underwent a major upgrade resulting in alternating compact and extended configurations. Other upgrades, including digital back-ends and a rapid-response triggering system, have been developed since the original array was commissioned. In this paper, we review the major results from the prior operation of the MWA and then discuss the new science paths enabled by the improved capabilities. We group these science opportunities by the four original science themes but also include ideas for directions outside these categories.
The Murchison Widefield Array (MWA) is an electronically steered low-frequency (<300 MHz) radio interferometer, with a ‘slew’ time less than 8 s. Low-frequency (∼100 MHz) radio telescopes are ideally suited for rapid response follow-up of transients due to their large field of view, the inverted spectrum of coherent emission, and the fact that the dispersion delay between a 1 GHz and 100 MHz pulse is on the order of 1–10 min for dispersion measures of 100–2000 pc/cm3. The MWA has previously been used to provide fast follow-up for transient events including gamma-ray bursts (GRBs), fast radio bursts (FRBs), and gravitational waves, using systems that respond to gamma-ray coordinates network packet-based notifications. We describe a system for automatically triggering MWA observations of such events, based on Virtual Observatory Event standard triggers, which is more flexible, capable, and accurate than previous systems. The system can respond to external multi-messenger triggers, which makes it well-suited to searching for prompt coherent radio emission from GRBs, the study of FRBs and gravitational waves, single pulse studies of pulsars, and rapid follow-up of high-energy superflares from flare stars. The new triggering system has the capability to trigger observations in both the regular correlator mode (limited to ≥0.5 s integrations) and using the Voltage Capture System (VCS, 0.1 ms integration) of the MWA and represents a new mode of operation for the MWA. The upgraded standard correlator triggering capability has been in use since MWA observing semester 2018B (July–Dec 2018), and the VCS and buffered mode triggers will become available for observing in a future semester.
The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.
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.
OBJECTIVES/SPECIFIC AIMS: To examine rural-urban disparities in prevalence of diagnosed diabetes in veterans receiving care at the VA and to determine the extent to which demographic factors and obesity levels contribute to identified disparities. METHODS/STUDY POPULATION: A retrospective serial cross-sectional analysis was employed. A stratified weighted random sample of veterans who received care at a VA facility was selected each year for 2007 through 2012. Rural Urban Commuting Area (RUCA) codes were based on resident zip code. Diabetes was defined by two or more primary or secondary ICD-9 codes for diabetes (250.xx) within a 12 month period. Data were analyzed using complex survey-specific procedures. RESULTS/ANTICIPATED RESULTS: Diabetes prevalence 2007-2012 was lowest in urban (20.5%-21.0%), followed by highly rural (21.1%-22.1%) and rural (22.3%-23.0%) areas with the prevalence being significantly higher on the insular islands (31.0%-32.4%). In 2012, 41% of urban, 43% of rural and highly rural and 30% of insular island veterans were obese. Relative to urban areas, the odds ratio for prevalent diabetes was 1.10 (95% CI: 1.08, 1.12) for rural veterans, 1.19 (95% CI: 1.16, 1.23) for insular island veterans, and 1.00 (95% CI: 0.98, 1.02) for highly rural veterans. DISCUSSION/SIGNIFICANCE OF IMPACT: Prevalence of diagnosed diabetes is high in veterans residing in rural, highly rural and urban areas, but markedly higher on the insular islands. Understanding the burden of disease and factors driving disparities provides information required to develop targeted interventions.
Bovine herpes virus 1 (BHV-1) manifests as a latent viral infection putatively affecting bovines. Understanding its effect on cattle herds is critical to maintaining sustainable beef and dairy production systems, as well as aiding in the development of herd health policies. The primary objective of the current study was, therefore, to use a whole-farm bio-economic model to evaluate the effect of herd seroprevalence to BHV-1 on the productive and economic performance of a spring calving beef cow herd. As part of a wider epidemiological study of herd pathogen status, a total of 4240 cows from 134 spring calving beef cow herds across the Republic of Ireland were blood sampled to measure the seroprevalence to BHV-1. Using data from a national breeding database, productive and reproductive performance indicators were used to parameterize a single year, static and deterministic whole-farm bio-economic model. A spring-calving, pasture-based suckler beef cow production system with an emphasis on calf-to-weanling production was simulated. The impact of BHV-1 seropositivity on whole-farm technical and economic performance was relatively small, with a marginal drop in the net margin of 4% relative to a baseline seronegative herd. Subsequent risk factors for increased pathogenicity were considered such as total herd size, percentage of intra-herd movements and vaccination status for BHV-1. In contrast to all others, scenarios representing herds that were either small in size or those which indicated an active vaccination policy for BHV-1 had no reduction in net margin against the baseline as a result of seropositivity to BHV-1.
The unsteady three-dimensional flow organization of jets issued from a duct with swirl vanes at Reynolds number equal to 1000 and swirl number
ranging between 0 and 0.8 is investigated. Time-resolved tomographic particle image velocimetry returns the instantaneous flow structure and its evolution by visualization of velocity and vortical features. The most relevant coherent motions are identified and characterized with the aid of dynamic mode decomposition. The time-averaged flow topology indicates that the vanes used to impart the swirling motion have a significant impact on the azimuthal modulation of momentum, with the jet exhibiting four sectors separated by a thin cross-like wake resulting from the boundary layer developed along the vane walls. The flow field is thus characterized by inner and outer shear regions. An increase in swirl, up to moderate levels (
), causes larger jet spreading angles. Further increase of the swirl number is accompanied by the appearance of a central recirculation zone due to vortex breakdown at
which increases in size and is triggered upstream for increasing
. Although no shear layer instability development is observed at
, already at
the swirling motion promotes the growth of helical vortices appearing as Kelvin–Helmholtz waves that deform the outer axial shear layer. The downstream evolution features successive pairing, which is observed for all the considered swirl numbers. The initial development of the instability is independent for each vane, whereas a mutual interaction between the vanes occurs after the vortex pairing. The reconnection from the four sectors vortices induces a significant increase of azimuthal vorticity, which affects the dynamical behaviour of the precessing vortex core. The latter is visualized by a low-order spatio-temporal reconstruction based on few dynamical modes. At a higher swirl number (
), the axial vorticity component dominates the flow field; it interacts with the azimuthal vorticity, which penetrates inward through the meanders of the vane wakes and forces the vortex core precession and breakdown.
The stability of VFB catholytes was investigated using both light-scattering measurements and visual observation. V2O5 precipitates after an induction time τ which shows an Arrhenius variation with temperature. The value of τ increases with increasing [S] and with decreasing [VV] but the activation energy remains constant with a value of (1.791±0.020) eV. Plots of ln τ against [S] and [VV] show good linearity and the slopes give values of βS = 2.073 M-1 and βV5 = –3.434 M-1 for the fractional rates of variation of τ with [S] and [VV], respectively. Combining the Arrhenius Equation with the observed log-linear variation of τ with [S] and [VV] provides a model for simulating the stability of catholytes. The addition of H3PO4 has a strong stabilizing effect on catholytes at higher temperatures. For example, at 50°C the induction time for precipitation for a typical catholyte is enhanced ∼ 12.5-fold by 0.1 M added H3PO4. At concentrations of H3PO4 less than ∼0.04 M, the precipitation time increases with increasing concentration at all temperatures investigated (30–70°C). At higher concentrations, induction time begins to decrease with increasing concentration of H3PO4: the changeover concentration depends on the temperature. Experiments at 70°C using other phosphate additives (sodium triphosphate, Na5P3O10, and sodium hexametaphosphate, (NaPO3)6) showed similar results to H3PO4.
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 ongoing Green Bank North Celestial Cap pulsar survey is using the Green Bank Telescope to search for pulsars and transients over 85% of the celestial sphere. The survey has resulted in over 150 new pulsars, among which are high-precision millisecond pulsars, several binary pulsars, including at least one relativistic double neutron star system, nulling pulsars, and several nearby millisecond pulsars. We find no fast radio bursts in the survey to date. We present these results and discuss the future prospects for the survey.
The millisecond pulsar PSR J0337+1715 is in a mildly relativistic hierarchical triple system with two white dwarfs. This offers the possibility of testing the universality of free fall: does the neutron star fall with the same acceleration as the inner white dwarf in the gravity of the outer white dwarf? We have carried out an intensive pulsar timing campaign, yielding some 27000 pulse time-of-arrival (TOA) measurements with a median uncertainty of 1.2 μs. Here we describe our analysis procedure and timing model.
PSR J0337+1715 is a millisecond radio pulsar in a hierarchical stellar triple system with two white dwarfs. This system is a unique and excellent laboratory in which to test the strong equivalence principle (SEP) of general relativity. An initial SEP-violation test was performed using direct 3-body numerical integration of the orbit in order to model the more than 25000 pulse times of arrival (TOAs) from three radio telescopes: Arecibo, Green Bank and Westerbork. In this work I present our efforts to quantify the effects of systematics in the TOAs and timing residuals, which limit the precision of an SEP test. In particular, we apply Fourier-based techniques to the timing residuals in order to isolate the effects of systematics that can masquerade as an SEP violation.
We present low-frequency spectral energy distributions of 60 known radio pulsars observed with the Murchison Widefield Array telescope. We searched the GaLactic and Extragalactic All-sky Murchison Widefield Array survey images for 200-MHz continuum radio emission at the position of all pulsars in the Australia Telescope National Facility (ATNF) pulsar catalogue. For the 60 confirmed detections, we have measured flux densities in 20 × 8 MHz bands between 72 and 231 MHz. We compare our results to existing measurements and show that the Murchison Widefield Array flux densities are in good agreement.
The Mapping Application for Penguin Populations and Projected Dynamics (MAPPPD) is a web-based, open access, decision-support tool designed to assist scientists, non-governmental organisations and policy-makers working to meet the management objectives as set forth by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) and other components of the Antarctic Treaty System (ATS) (that is, Consultative Meetings and the ATS Committee on Environmental Protection). MAPPPD was designed specifically to complement existing efforts such as the CCAMLR Ecosystem Monitoring Program (CEMP) and the ATS site guidelines for visitors. The database underlying MAPPPD includes all publicly available (published and unpublished) count data on emperor, gentoo, Adélie and chinstrap penguins in Antarctica. Penguin population models are used to assimilate available data into estimates of abundance for each site and year. Results are easily aggregated across multiple sites to obtain abundance estimates over any user-defined area of interest. A front end web interface located at www.penguinmap.com provides free and ready access to the most recent count and modelled data, and can act as a facilitator for data transfer between scientists and Antarctic stakeholders to help inform management decisions for the continent.
The stability of vanadium flow battery (VFB) catholytes was investigated using both lightscattering measurements and visual observation. V2O5 precipitates after an induction time τ which shows an Arrhenius variation with temperature. The value of τ increases with increasing concentration of sulfate and with decreasing concentration of VV but the activation energy remains constant with a value of (1.791±0.020) eV. Plots of ln τ against [S] and [VV] show good linearity and the slopes give values of βS = 2.073 M-1 and βV5 = –3.434 M-1 for the fractional rates of variation of τ with [S] and [VV], respectively. Combining the Arrhenius Equation with the observed log-linear variation of τ with [S] and [VV] provides a model for simulating the stability of catholytes.
Using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), it was shown for four different types of carbon that electrode treatments at negative potentials enhance the kinetics of VIV-VV and inhibit the kinetics of VII-VIII while electrode treatments at positive potentials inhibit the kinetics of VIV-VV and enhance the kinetics of VII-VIII. These observations may explain conflicting reports in the literature. The potentials required for activation and deactivation of electrodes were examined in detail. The results suggest that interchanging the positive and negative electrodes in a vanadium flow battery (VFB) would reduce the overpotential at the negative electrode and so improve the performance. This is supported by flow-cell experiments. Thus, periodic catholyte-anolyte interchange, or equivalent alternatives such as battery overdischarge, show promise of improving the voltage efficiency of VFBs.