607 research outputs found
Evaluating the impact of cycle helmet use on severe traumatic brain injury and death in a national cohort of over 11000 pedal cyclists : a retrospective study from the NHS England trauma audit and research network dataset
Objectives
In the last 10 years there has been a significant increase in cycle traffic in the UK, with an associated increase in the overall number of cycling injuries. Despite this, and the significant media, political and public health debate into this issue, there remains an absence of studies from the UK assessing the impact of helmet use on rates of serious injury presenting to the National Health Service (NHS) in cyclists.
Setting
The NHS England Trauma Audit and Research Network (TARN) Database was interrogated to identify all adult (≥16 years) patients presenting to hospital with cycling-related major injuries, during a period from 14 March 2012 to 30 September 2017 (the last date for which a validated dataset was available).
Participants
11 patients met inclusion criteria. Data on the use of cycling helmets were available in 6621 patients.
Outcome measures
TARN injury descriptors were used to compare patterns of injury, care and mortality in helmeted versus non-helmeted cohorts.
Results
Data on cycle helmet use were available for 6621 of the 11 192 cycle-related injuries entered onto the TARN Database in the 66 months of this study (93 excluded as not pedal cyclists). There was a significantly higher crude 30-day mortality in un-helmeted cyclists 5.6% (4.8%–6.6%) versus helmeted cyclists 1.8% (1.4%–2.2%) (p<0.001). Cycle helmet use was also associated with a reduction in severe traumatic brain injury (TBI) 19.1% (780, 18.0%–20.4%) versus 47.6% (1211, 45.6%–49.5%) (p<0.001), intensive care unit requirement 19.6% (797, 18.4%–20.8%) versus 27.1% (691, 25.4%–28.9%) (p<0.001) and neurosurgical intervention 2.5% (103, 2.1%–3.1%) versus 8.5% (217, 7.5%–9.7%) (p<0.001). There was a statistically significant increase in chest, spinal, upper and lower limb injury in the helmeted group in comparison to the un-helmeted group (all p<0.001), though in a subsequent analysis of these anatomical injury patterns, those cyclists wearing helmets were still found to have lower rates of TBI. In reviewing TARN injury codes for specific TBI and facial injuries, there was a highly significant decrease in rates of impact injury between cyclists wearing helmets and those not.
Conclusions
This study suggests that there is a significant correlation between use of cycle helmets and reduction in adjusted mortality and morbidity associated with TBI and facial injury
Deep Inelastic Scattering from off-Shell Nucleons
We derive the general structure of the hadronic tensor required to describe
deep-inelastic scattering from an off-shell nucleon within a covariant
formalism. Of the large number of possible off-shell structure functions we
find that only three contribute in the Bjorken limit. In our approach the usual
ambiguities encountered when discussing problems related to off-shellness in
deep-inelastic scattering are not present. The formulation therefore provides a
clear framework within which one can discuss the various approximations and
assumptions which have been used in earlier work. As examples, we investigate
scattering from the deuteron, nuclear matter and dressed nucleons. The results
of the full calculation are compared with those where various aspects of the
off-shell structure are neglected, as well as with those of the convolution
model.Comment: 36 pages RevTeX, 9 figures (available upon request), ADP-93-210/T128,
PSI-PR-93-13, accepted for publication in Physical Review
Predictive powers of chiral perturbation theory in Compton scattering off protons
We study low-energy nucleon Compton scattering in the framework of baryon
chiral perturbation theory (BPT) with pion, nucleon, and (1232)
degrees of freedom, up to and including the next-to-next-to-leading order
(NNLO). We include the effects of order , and , with
MeV the -resonance excitation energy. These are
all "predictive" powers in the sense that no unknown low-energy constants enter
until at least one order higher (i.e, ). Estimating the theoretical
uncertainty on the basis of natural size for effects, we find that
uncertainty of such a NNLO result is comparable to the uncertainty of the
present experimental data for low-energy Compton scattering. We find an
excellent agreement with the experimental cross section data up to at least the
pion-production threshold. Nevertheless, for the proton's magnetic
polarizability we obtain a value of fm, in
significant disagreement with the current PDG value. Unlike the previous
PT studies of Compton scattering, we perform the calculations in a
manifestly Lorentz-covariant fashion, refraining from the heavy-baryon (HB)
expansion. The difference between the lowest order HBPT and BPT
results for polarizabilities is found to be appreciable. We discuss the chiral
behavior of proton polarizabilities in both HBPT and BPT with the
hope to confront it with lattice QCD calculations in a near future. In studying
some of the polarized observables, we identify the regime where their naive
low-energy expansion begins to break down, thus addressing the forthcoming
precision measurements at the HIGS facility.Comment: 24 pages, 9 figures, RevTeX4, revised version published in EPJ
Astroparticle Physics with a Customized Low-Background Broad Energy Germanium Detector
The MAJORANA Collaboration is building the MAJORANA DEMONSTRATOR, a 60 kg
array of high purity germanium detectors housed in an ultra-low background
shield at the Sanford Underground Laboratory in Lead, SD. The MAJORANA
DEMONSTRATOR will search for neutrinoless double-beta decay of 76Ge while
demonstrating the feasibility of a tonne-scale experiment. It may also carry
out a dark matter search in the 1-10 GeV/c^2 mass range. We have found that
customized Broad Energy Germanium (BEGe) detectors produced by Canberra have
several desirable features for a neutrinoless double-beta decay experiment,
including low electronic noise, excellent pulse shape analysis capabilities,
and simple fabrication. We have deployed a customized BEGe, the MAJORANA
Low-Background BEGe at Kimballton (MALBEK), in a low-background cryostat and
shield at the Kimballton Underground Research Facility in Virginia. This paper
will focus on the detector characteristics and measurements that can be
performed with such a radiation detector in a low-background environment.Comment: Submitted to NIMA Proceedings, SORMA XII. 9 pages, 4 figure
Confining QCD Strings, Casimir Scaling, and a Euclidean Approach to High-Energy Scattering
We compute the chromo-field distributions of static color-dipoles in the
fundamental and adjoint representation of SU(Nc) in the loop-loop correlation
model and find Casimir scaling in agreement with recent lattice results. Our
model combines perturbative gluon exchange with the non-perturbative stochastic
vacuum model which leads to confinement of the color-charges in the dipole via
a string of color-fields. We compute the energy stored in the confining string
and use low-energy theorems to show consistency with the static quark-antiquark
potential. We generalize Meggiolaro's analytic continuation from parton-parton
to gauge-invariant dipole-dipole scattering and obtain a Euclidean approach to
high-energy scattering that allows us in principle to calculate S-matrix
elements directly in lattice simulations of QCD. We apply this approach and
compute the S-matrix element for high-energy dipole-dipole scattering with the
presented Euclidean loop-loop correlation model. The result confirms the
analytic continuation of the gluon field strength correlator used in all
earlier applications of the stochastic vacuum model to high-energy scattering.Comment: 65 pages, 13 figures, extended and revised version to be published in
Phys. Rev. D (results unchanged, 2 new figures, 1 new table, additional
discussions in Sec.2.3 and Sec.5, new appendix on the non-Abelian Stokes
theorem, old Appendix A -> Sec.3, several references added
Effective Lagrangian Approach to the Theory of Eta Photoproduction in the Region
We investigate eta photoproduction in the resonance region
within the effective Lagrangian approach (ELA), wherein leading contributions
to the amplitude at the tree level are taken into account. These include the
nucleon Born terms and the leading -channel vector meson exchanges as the
non-resonant pieces. In addition, we consider five resonance contributions in
the - and - channel; besides the dominant , these are:
and . The amplitudes for the
and the photoproduction near threshold have significant
differences, even as they share common contributions, such as those of the
nucleon Born terms. Among these differences, the contribution to the
photoproduction of the -channel excitation of the is the most
significant. We find the off-shell properties of the spin-3/2 resonances to be
important in determining the background contributions. Fitting our effective
amplitude to the available data base allows us to extract the quantity
, characteristic of the
photoexcitation of the resonance and its decay into the
-nucleon channel, of interest to precise tests of hadron models. At the
photon point, we determine it to be from
the old data base, and from a
combination of old data base and new Bates data. We obtain the helicity
amplitude for to be from the old data base, and from the combination of the old data base and new Bates
data, compared with the results of the analysis of pion photoproduction
yielding , in the same units.Comment: 43 pages, RevTeX, 9 figures available upon request, to appear in
Phys. Rev.
Measurement of the Charged Multiplicities in b, c and Light Quark Events from Z0 Decays
Average charged multiplicities have been measured separately in , and
light quark () events from decays measured in the SLD experiment.
Impact parameters of charged tracks were used to select enriched samples of
and light quark events, and reconstructed charmed mesons were used to select
quark events. We measured the charged multiplicities:
,
, from
which we derived the differences between the total average charged
multiplicities of or quark events and light quark events: and . We compared
these measurements with those at lower center-of-mass energies and with
perturbative QCD predictions. These combined results are in agreement with the
QCD expectations and disfavor the hypothesis of flavor-independent
fragmentation.Comment: 19 pages LaTex, 4 EPS figures, to appear in Physics Letters
Desenvolvimento folicular e desempenho produtivo no início do ciclo de postura em duas raças de poedeiras
The ExaVolt Antenna: A Large-Aperture, Balloon-embedded Antenna for Ultra-high Energy Particle Detection
We describe the scientific motivation, experimental basis, design
methodology, and simulated performance of the ExaVolt Antenna (EVA) mission,
and planned ultra-high energy (UHE) particle observatory under development for
NASA's suborbital super-pressure balloon program in Antarctica. EVA will
improve over ANITA's integrated totals - the current state-of-the-art in UHE
suborbital payloads - by 1-2 orders of magnitude in a single flight. The design
is based on a novel application of toroidal reflector optics which utilizes a
super-pressure balloon surface, along with a feed-array mounted on an inner
membrane, to create an ultra-large radio antenna system with a synoptic view of
the Antarctic ice sheet below it. Radio impulses arise via the Askaryan effect
when UHE neutrinos interact within the ice, or via geosynchrotron emission when
UHE cosmic rays interact in the atmosphere above the continent. EVA's
instantaneous antenna aperture is estimated to be several hundred square meters
for detection of these events within a 150-600 MHz band. For standard
cosmogenic UHE neutrino models, EVA should detect of order 30 events per flight
in the EeV energy regime. For UHE cosmic rays, of order 15,000 geosynchrotron
events would be detected in total, several hundred above 10 EeV, and of order
60 above the GZK cutoff energyComment: 20 pages, 14 figures; introductory section shortened; additional
horizontal polarization simulation results included. In final review for
Astroparticle Physic
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