252 research outputs found
Osmium isotope evidence for two pulses of increased continental weathering linked to Early Jurassic volcanism and climate change
Large igneous provinces (LIPs) are proposed to have caused a number of episodes of abrupt environmental change by increasing atmospheric CO2 levels, which were subsequently alleviated by drawdown of CO2 via enhanced continental weathering and burial of organic matter. Here the sedimentary records of two such episodes of environmental change, the Toarcian oceanic anoxic event (T-OAE) and preceding Pliensbachian–Toarcian (Pl-To) event (both possibly linked to the Karoo-Ferrar LIP), are investigated using a new suite of geochemical proxies that have not been previously compared. Stratigraphic variations in osmium isotope (187Os/188Os) records are compared with those of mercury (Hg) and carbon isotopes (d13C) in samples from the Mochras core, Llanbedr Farm, Cardigan Bay Basin, Wales. These sedimentary rocks are confirmed as recording an open-marine setting by analysis of molybdenum/uranium enrichment trends, indicating that the Os isotope record in these samples reflects the isotopic composition of the global ocean. The Os isotope data include the first results across the Pl-To boundary, when seawater 187Os/188Os increased from ~0.40 to ~0.53, in addition to new data that show elevated 187Os/188Os (from ~0.42 to ~0.68) during the T-OAE. Both increases in 187Os/188Os correlate with negative carbon isotope excursions and increased mercury concentrations, supporting an interplay between terrestrial volcanism, weathering, and climate that was instrumental in driving these distinct episodes of global environmental change. These observations also indicate that the environmental impact of the Karoo-Ferrar LIP was not limited solely to the T-OAE
Emergency hospital care for adults with suspected seizures in the NHS in England 2007-2013: a cross-sectional study
Aims To quantify the frequency, characteristics, geographical variation and costs of emergency hospital care for suspected seizures.
Design Cross-sectional study using routinely collected data (Hospital Episode Statistics).
Setting The National Health Service in England 2007–2013.
Participants Adults who attended an emergency department (ED) or were admitted to hospital.
Results In England (population 2011: 53.11 million, 41.77 million adults), suspected seizures gave rise to 50 111 unscheduled admissions per year among adults (≥18 years). This is 47.1% of unscheduled admissions for neurological conditions and 0.71% of all unscheduled admissions. Only a small proportion of admissions for suspected seizures were coded as status epilepticus (3.5%) and there were a very small number of dissociative (non-epileptic) seizures. The median length of stay for each admission was 1 day, the median cost for each admission was £1651 (116.2 million) per year. 16.8% of patients had more than one admission per year. There was significant geographical variability in the rate of admissions corrected for population age and gender differences and some areas had rates of admission which were consistently higher than the average.
Conclusions Our data show that suspected seizures are the most common neurological cause of admissions to hospital in England, that readmissions are common and that there is significant geographical variability in admission rates. This variability has not previously been reported in the published literature. The cause of the geographical variation is unknown; important factors are likely to include prevalence, deprivation and clinical practice and these require further investigation. Dissociative seizures are not adequately diagnosed during ED attendances and hospital admissions
The impact of accelerator processors for high-throughput molecular modeling and simulation
Accepted versio
Measurement of the Nucleon Structure Function F2 in the Nuclear Medium and Evaluation of its Moments
We report on the measurement of inclusive electron scattering off a carbon
target performed with CLAS at Jefferson Laboratory. A combination of three
different beam energies 1.161, 2.261 and 4.461 GeV allowed us to reach an
invariant mass of the final-state hadronic system W~2.4 GeV with four-momentum
transfers Q2 ranging from 0.2 to 5 GeV2. These data, together with previous
measurements of the inclusive electron scattering off proton and deuteron,
which cover a similar continuous two-dimensional region of Q2 and Bjorken
variable x, permit the study of nuclear modifications of the nucleon structure.
By using these, as well as other world data, we evaluated the F2 structure
function and its moments. Using an OPE-based twist expansion, we studied the
Q2-evolution of the moments, obtaining a separation of the leading-twist and
the total higher-twist terms. The carbon-to-deuteron ratio of the leading-twist
contributions to the F2 moments exhibits the well known EMC effect, compatible
with that discovered previously in x-space. The total higher-twist term in the
carbon nucleus appears, although with large systematic uncertainites, to be
smaller with respect to the deuteron case for n<7, suggesting partial parton
deconfinement in nuclear matter. We speculate that the spatial extension of the
nucleon is changed when it is immersed in the nuclear medium.Comment: 37 pages, 15 figure
Precise Measurements of Beam Spin Asymmetries in Semi-Inclusive production
We present studies of single-spin asymmetries for neutral pion
electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV
polarized electrons from an unpolarized hydrogen target, using the CEBAF Large
Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator
Facility. A substantial amplitude has been measured in the
distribution of the cross section asymmetry as a function of the azimuthal
angle of the produced neutral pion. The dependence of this amplitude
on Bjorken and on the pion transverse momentum is extracted with
significantly higher precision than previous data and is compared to model
calculations.Comment: to be submitted PL
First measurement of direct photoproduction on the proton
We report on the results of the first measurement of exclusive
meson photoproduction on protons for GeV and GeV. Data were collected with the CLAS detector at the Thomas
Jefferson National Accelerator Facility. The resonance was detected via its
decay in the channel by performing a partial wave analysis of the
reaction . Clear evidence of the meson
was found in the interference between and waves at GeV. The -wave differential cross section integrated in the mass range of
the was found to be a factor of 50 smaller than the cross section
for the meson. This is the first time the meson has been
measured in a photoproduction experiment
Prehospital early warning scores for adults with suspected sepsis: retrospective diagnostic cohort study
Background Ambulance services need to identify and prioritise patients with sepsis for early hospital assessment. We aimed to determine the accuracy of early warning scores alongside paramedic diagnostic impression to identify sepsis that required urgent treatment.
Methods We undertook a retrospective diagnostic cohort study involving adult emergency medical cases transported to Sheffield Teaching Hospitals ED by Yorkshire Ambulance Service in 2019. We used routine ambulance service data to calculate 21 early warning scores and categorise paramedic diagnostic impressions as sepsis, infection, non-specific presentation or other presentation. We linked cases to hospital records and identified those meeting the sepsis-3 definition who received urgent hospital treatment for sepsis (reference standard). Analysis determined the accuracy of strategies that combined early warning scores at varying thresholds for positivity with paramedic diagnostic impression.
Results We linked 12 870/24 955 (51.6%) cases and identified 348/12 870 (2.7%) with a positive reference standard. None of the strategies provided sensitivity greater than 0.80 with positive predictive value greater than 0.15. The area under the receiver operating characteristic curve for the National Early Warning Score, version 2 (NEWS2) applied to patients with a diagnostic impression of sepsis or infection was 0.756 (95% CI 0.729, 0.783). No other early warning score provided clearly superior accuracy to NEWS2. Paramedic impression of sepsis or infection had sensitivity of 0.572 (0.519, 0.623) and positive predictive value of 0.156 (0.137, 0.176). NEWS2 thresholds of >4, >6 and >8 applied to patients with a diagnostic impression of sepsis or infection, respectively, provided sensitivities and positive predictive values of 0.522 (0.469, 0.574) and 0.216 (0.189, 0.245), 0.447 (0.395, 0.499) and 0.274 (0.239, 0.313), and 0.314 (0.268, 0.365) and 0.333 (0.284, 0.386).
Conclusion No strategy is ideal but using NEWS2 alongside paramedic diagnostic impression of infection or sepsis could identify one-third to half of sepsis cases without prioritising unmanageable numbers. No other score provided clearly superior accuracy to NEWS2
Evidence for the Onset of Color Transparency in Electroproduction off Nuclei
We have measured the nuclear transparency of the incoherent diffractive
process in C and Fe targets relative to H
using a 5 GeV electron beam. The nuclear transparency, the ratio of the
produced 's on a nucleus relative to deuterium, which is sensitive to
interaction, was studied as function of the coherence length (),
a lifetime of the hadronic fluctuation of the virtual photon, and the
four-momentum transfer squared (). While the transparency for both
C and Fe showed no dependence, a significant
dependence was measured, which is consistent with calculations that included
the color transparency effects.Comment: 6 pages and 4 figure
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