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We numerically model the dynamics of the Enceladus plume ice grains and define our nominal plume model as having a particle size distribution n(R) ~ R−q with q = 4 and a total particulate mass rate of 16 kg s−1. This mass rate is based on average plume brightness observed by Cassini across a range of orbital positions. The model predicts sample volumes of ~1600 µg for a 1 m2 collector on a spacecraft making flybys at 20–60 km altitudes above the Enceladus surface. We develop two scenarios to predict the concentration of amino acids in the plume based on these assumed sample volumes. We specifically consider Glycine, Serine, α-Alanine, α-Aminoisobutyric acid and Isovaline. The first ‘abiotic’ model assumes that Enceladus has the composition of a comet and finds abundances between 2 × 10−6 to 0.003 µg for dissolved free amino acids and 2 × 10−5 to 0.3 µg for particulate amino acids. The second ‘biotic’ model assumes that the water of Enceladus's ocean has the same amino acid composition as the deep ocean water on Earth. We compute the expected captured mass of amino acids such as Glycine, Serine, and α-Alanine in the ‘biotic’ model to be between 1 × 10−5 to 2 × 10−5 µg for dissolved free amino acids and dissolved combined amino acids and about 0.0002 µg for particulate amino acids. Both models consider enhancements due to bubble bursting. Expected captured mass of amino acids is calculated for a 1 m2 collector on a spacecraft making flybys with a closest approach of 20 km during mean plume activity for the given nominal particle size distribution.
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.
Drillholes made by naticid and muricid gastropods are frequently used in evolutionary and ecological studies because they provide direct, preservable evidence of predation. The muricid Ecphora is common in many Neogene Atlantic Coastal Plain assemblages in the United States, but is frequently ignored in studies of naticid predation. We used a combination of Pliocene fossil, modern beach, and experimentally derived samples to evaluate the hypothesis that Ecphora was an important source of drillholes in infaunal bivalve prey shared with naticids. We focused on the large, thick-shelled venerid, Mercenaria, which is commonly drilled by naticids today. Laboratory experiments, modern beach samples, and the published literature confirm that naticids preferentially drill near the umbo (significant clumping of holes), show a significant correlation between prey size and predator size (estimated by outer borehole diameter), and prefer Mercenaria <50 mm antero-posterior width when other prey are present. Fossil samples containing Ecphora (with or without other large muricids) show no drillhole site stereotypy (no significant clumping, greater variability in placement), no significant predator: prey size correlation, drilled prey shells larger than the largest modern naticids could produce in an experimental setting, and drillholes larger in diameter than those estimated for the largest Pliocene naticids, thus supporting our hypothesis. Substantial overlap in the placement of holes drilled by naticids and muricids, however, made identifying predators from drillhole position problematic. The lack of overlapping ranges of prey shell thickness between fossil and other samples precluded the use of drillhole morphology to establish predator identity (e.g., ratio of inner borehole diameter to outer borehole diameter, drillhole angle). Whereas the difficulty in determining predator identity from drillholes limits the types of analyses that can be reliably performed in mixed-predator assemblages, recognizing Ecphora as a prominent drilling predator creates the opportunity to investigate previously unrecognized questions.
Thomas Hardy came to the writer’s life with prodigious endowments and little self-confidence. His struggle with this unlikely predicament shows up repeatedly in his career, but nowhere so often as in its early stages. The “Studies and Specimens” Notebook, completed in the mid-1860s, bears touching witness to the labor of a greatly gifted writer teaching himself the very rudiments of literary form. The editors of the notebook speak accurately of the “diligence and doggedness” of his striving (Dalziel and Millgate xv). At the time his striving was dedicated to mastering poetry, the first and always most favored of his muses. But in 1867 “under the stress of necessity” he shifted his focus to “a kind of literature in which he had hitherto taken but little interest – prose fiction” (Life and Work of Thomas Hardy 58). With varying results he turned to writing novels, still testing his vocation until 1873 when he published A Pair of Blue Eyes, which, together with his impending marriage, fixed his literary course for decades to come.
The neurocognitive deficits and other correlates of problem gambling are also observable in individuals with lower cognitive abilities, suggesting that a low IQ may be a determinant of problem gambling. There has been very little research into this possibility. This study aimed to investigate the characteristics associated with problem gambling in a large population-based study in England, with a particular focus on IQ.
The Adult Psychiatric Morbidity Survey (APMS) 2007 comprised detailed interviews with 7403 individuals living in private households in England. Problem gambling was ascertained using a questionnaire based on DSM-IV criteria. Verbal IQ was estimated using the National Adult Reading Test (NART). Confounders included socio-economic and demographic factors, common mental disorders, impulsivity, smoking, and hazardous drug and alcohol use.
More than two-thirds of the population reported engaging in some form of gambling in the previous year, but problem gambling was rare [prevalence 0.7%, 95% confidence interval (CI) 0.5–1.0]. The odds of problem gambling doubled with each standard deviation drop in estimated verbal IQ [adjusted odds ratio (OR) 2.1, 95% CI 1.3–3.4, p = 0.003], after adjusting for other characteristics associated with problem gambling including age, sex, socio-economic factors, drug and alcohol dependence, smoking, impulsivity and common mental disorders. There was no strong relationship observed between IQ and non-problem gambling.
People with lower IQs may be at a higher risk of problem gambling. Further work is required to replicate and study the mechanisms behind these findings, and may aid the understanding of problem gambling and inform preventative measures and interventions.
In the aftermath of the major earthquake that hit Pakistan in 2005, there appeared to be a paucity of psychometric tools validated in Urdu. It was decided to translate the Impact of Event Scale - Revised (IES-R) so as to obtain an internationally validated and recognised psychometric tool for use in research into post-traumatic stress disorder. The resulting Urdu and English versions of the IES-R were compared for linguistic, conceptual and scale equivalence. The Urdu version of the IES-R (UIES-R) can be used for clinical, psychological trauma populations in Pakistan with evidence of good reliability and satisfactory validity. In trauma research in Pakistan the UIES-R will be an extremely useful psychometric tool.
In utero diagnosis of complex progressive cardiac disease such as hypoplastic left heart syndrome presents a novel opportunity for antepartum, intrapartum, and neonatal management. The clinical possibilities and potential for differing outcomes challenge the mother–foetus dyad with regard to informed consent. Previous studies reveal that rates of termination of pregnancy for foetuses with hypoplastic left heart syndrome vary widely in the United States and Europe, leading us to surmise that informed consent may be practised differently. The purpose of this paper is to review the ethical considerations and physician responsibilities of informed consent as they relate to prenatal and postnatal patients with hypoplastic left heart syndrome. Special consideration is paid to the informed consent process as practised by the obstetrician, perinatologist, paediatric cardiologist, and paediatric cardiac surgeon as it relates to termination of pregnancy, comfort care, and surgical palliation. We will argue that informed consent as it relates to hypoplastic left heart syndrome is far from standardised and that there exists a state of bioethical equipoise concerning the extent and limits of its application in the current clinical setting.
Foraminiferal analyses of 404 contiguous samples, supported by diatom, lithologic, geochronologic and seismic data, reveal both rapid and gradual Holocene paleoenvironmental changes in an 8.21-m vibracore taken from southern Pamlico Sound, North Carolina. Data record initial flooding of a latest Pleistocene river drainage and the formation of an estuary 9000 yr ago. Estuarine conditions were punctuated by two intervals of marine influence from approximately 4100 to 3700 and 1150 to 500 cal yr BP. Foraminiferal assemblages in the muddy sand facies that accumulated during these intervals contain many well-preserved benthic foraminiferal species, which occur today in open marine settings as deep as the mid shelf, and significant numbers of well-preserved planktonic foraminifera, some typical of Gulf Stream waters. We postulate that these marine-influenced units resulted from temporary destruction of the southern Outer Banks barrier islands by hurricanes. The second increase in marine influence is coeval with increased rate of sea-level rise and a peak in Atlantic tropical cyclone activity during the Medieval Climate Anomaly. This high-resolution analysis demonstrates the range of environmental variability and the rapidity of coastal change that can result from the interplay of changing climate, sea level and geomorphology in an estuarine setting.