709 research outputs found
Does Medical Staffing Influence Perceived Safety? An International Survey on Medical Crew Models in Helicopter Emergency Medical Services
Objective: The competence, composition, and number of crewmembers have generally been considered to influence the degree of patient care and safety in helicopter emergency medical services (HEMS), but evidence to support the advantages of one crew concept over another is ambiguous; additionally, the benefit of physicians as crewmembers is still highly debated.
Methods: To compare perceived safety in different medical crew models, we surveyed international HEMS medical directors regarding the types of crew compositions their system currently used and their supportive rationales and to evaluate patient and flight safety within their services.
Results: Perceived patient and flight safety is higher when HEMS is staffed with a dual medical crew in the cabin. Tradition and scientific evidence are the most common reasons for the choice of medical crew. Most respondents would rather retain their current crew configuration, but some would prefer to add a physician or supplement the physician with an assistant in the cabin.
Conclusion: Our survey shows a wide variety of medical staffing models in HEMS and indicates that these differences are mainly related to medical competencies and the availability of an assistant in the medical cabin. The responses suggest that differences in medical staffing influence perceived flight and patient safety.publishedVersio
Inferring the eccentricity distribution
Standard maximum-likelihood estimators for binary-star and exoplanet
eccentricities are biased high, in the sense that the estimated eccentricity
tends to be larger than the true eccentricity. As with most non-trivial
observables, a simple histogram of estimated eccentricities is not a good
estimate of the true eccentricity distribution. Here we develop and test a
hierarchical probabilistic method for performing the relevant meta-analysis,
that is, inferring the true eccentricity distribution, taking as input the
likelihood functions for the individual-star eccentricities, or samplings of
the posterior probability distributions for the eccentricities (under a given,
uninformative prior). The method is a simple implementation of a hierarchical
Bayesian model; it can also be seen as a kind of heteroscedastic deconvolution.
It can be applied to any quantity measured with finite precision--other orbital
parameters, or indeed any astronomical measurements of any kind, including
magnitudes, parallaxes, or photometric redshifts--so long as the measurements
have been communicated as a likelihood function or a posterior sampling.Comment: Ap
Indledning: Etik i arbejdslivet
Ethos, det græske ord for ’sædvane’, og etik beskæftiger sig som regel med at udforske det gode i den menneskelige praksis, handling eller adfærd. Eftersom at arbejde er at virke, at skabe, og dermed beskæftige sig med praksis og handling, må etik og etiske spørgsmål allerede i udgangspunktet være vævet ind i arbejdslivets mangfoldige udtryks- og udfoldelsesformer. Som det vil fremgå, er afsættet for denne indledning dermed, at etik altid i udgangspunktet er vævet ind i arbejdslivets praksisser. Det behøver dog slet ikke at være ensbetydende med, at vi indtager et hverken refl ekteret eller refl eksivt forhold til de etiske perspektiver. Som det vil fremgå i det følgende, er det faktisk oftere det modsatte, der er tilfældet: etiske spørgsmål forbliver tavse og urefl ekterede. Det etiske er altid til stede, men er ofte foldet ind i arbejdslivets praksisser. Etiske perspektiver er vævet ind i den måde fagprofessioner handler på; den måde organisationer bliver kønnede; de opfordringsstrukturer som bæres ind med nye teknologier; den måde forandringsprocesser (u)intenderet ændrer på magtfordelingen på osv. Dette temanummer bidrager med at åbne op for nogle få af de sorte bokse, som netop etiske spørgsmål udgør inden for arbejdslivsområdet. De forskellige bidrag tjener som potentielle eksemplariske cases på, hvordan vi andre kan anlægge etiske perspektiver på vores egne dilemmaer og paradokser inden for arbejdslivet. Det vil formentlig også allerede i indledningen stå klart, at den største udfordring ved at rejse et tema som etik i arbejdslivet er, at det bogstavelig talt er et Sisyfos arbejde, fordi etiske spørgsmål ingen absolutte eller essentielle svar kan give. At det synes at være et Sisyfos arbejde kan være årsagen til, at etik fylder så relativt lidt: Opgaven med at drøfte etiske perspektiver synes at være en uendelig opgave, som ingen absolutte svar giver og derfor meget let kan blive oplevet som en akademisk eller fi losofi sk øvelse. På samme tid, er etiske spørgsmål paradoksalt nok også allestedsnærværende, fordi de handler om vores hverdagspraksisser og fordi de, som nævnt ovenfor, er vævet ind i vores omgang med hinanden
Dynamical inference from a kinematic snapshot: The force law in the Solar System
If a dynamical system is long-lived and non-resonant (that is, if there is a
set of tracers that have evolved independently through many orbital times), and
if the system is observed at any non-special time, it is possible to infer the
dynamical properties of the system (such as the gravitational force or
acceleration law) from a snapshot of the positions and velocities of the tracer
population at a single moment in time. In this paper we describe a general
inference technique that solves this problem while allowing (1) the unknown
distribution function of the tracer population to be simultaneously inferred
and marginalized over, and (2) prior information about the gravitational field
and distribution function to be taken into account. As an example, we consider
the simplest problem of this kind: We infer the force law in the Solar System
using only an instantaneous kinematic snapshot (valid at 2009 April 1.0) for
the eight major planets. We consider purely radial acceleration laws of the
form a_r = -A [r/r_0]^{-\alpha}, where r is the distance from the Sun. Using a
probabilistic inference technique, we infer 1.989 < \alpha < 2.052 (95 percent
interval), largely independent of any assumptions about the distribution of
energies and eccentricities in the system beyond the assumption that the system
is phase-mixed. Generalizations of the methods used here will permit, among
other things, inference of Milky Way dynamics from Gaia-like observations
Early goal-directed nutrition in icU patients (EAT-ICU):protocol for a randomised trial
INTRODUCTION: Extensive weight loss has been documented in intensive care unit (ICU) survivors, primarily as the result of muscle loss, leading to impaired physical function and reduced quality of life. The aim of the EAT-ICU trial is to test the effect of early goal-directed protein-energy nutrition based on measured requirements on short-term clinical outcomes and long-term physical quality of life in ICU patients. METHODS: The EAT-ICU trial is a single-centre, randomised, parallel-group trial with concealed allocation and blinded outcome assessment. A total of 200 consecutive, acutely admitted, mechanically ventilated intensive care patients will be randomised 1: 1 to early goal-directed nutrition versus standard of care to show a potential 15% relative risk reduction in the primary outcome measure (physical function) at six months (two-sided significance level alpha = 0.05; power beta = 80%). Secondary outcomes include energy-and protein balances, metabolic control, new organ failure, use of life support, nosocomial infections, ICU- and hospital length of stay, mortality and cost analyses. CONCLUSION : The optimal nutrition strategy for ICU patients remains unsettled. The EAT-ICU trial will provide important data on the effects of early goal-directed proteinenergy nutrition based on measured requirements in these patients.Copenhagen University Hospital; Rigshospitalet; Fresenius Kabi A/S; European Society for Clinical Nutrition and Metabolism (ESPEN)SCI(E)[email protected]
Spintronic magnetic anisotropy
An attractive feature of magnetic adatoms and molecules for nanoscale
applications is their superparamagnetism, the preferred alignment of their spin
along an easy axis preventing undesired spin reversal. The underlying magnetic
anisotropy barrier --a quadrupolar energy splitting-- is internally generated
by spin-orbit interaction and can nowadays be probed by electronic transport.
Here we predict that in a much broader class of quantum-dot systems with spin
larger than one-half, superparamagnetism may arise without spin-orbit
interaction: by attaching ferromagnets a spintronic exchange field of
quadrupolar nature is generated locally. It can be observed in conductance
measurements and surprisingly leads to enhanced spin filtering even in a state
with zero average spin. Analogously to the spintronic dipolar exchange field,
responsible for a local spin torque, the effect is susceptible to electric
control and increases with tunnel coupling as well as with spin polarization.Comment: 6 pages with 4 figures + 26 pages of Supplementary Informatio
Risk of epilepsy after traumatic brain injury: a nationwide Norwegian matched cohort study
BackgroundPost-traumatic epilepsy (PTE) is a well-known complication of traumatic brain injury (TBI). Although several risk factors have been identified, prediction of PTE is difficult. Changing demographics and advances in TBI treatment may affect the risk of PTE. Our aim was to provide an up-to-date estimate of the incidence of PTE by linking multiple nationwide registers.MethodsPatients with TBI admitted to hospital 2015–2018 were identified in the Norwegian Trauma Registry and matched to trauma-free controls on sex and birth year according to a matched cohort design. They were followed up for epilepsy in nationwide registers 2015–2020. Cumulative incidence of epilepsy in TBI patients and controls was estimated taking competing risks into account. Analyses stratified by the Abbreviated Injury Scale (AIS) severity score, Glasgow Coma Scale score and age were conducted for the TBI group. Occurrence of PTE in different injury types was visualized using UpSet plots.ResultsIn total, 8,660 patients and 84,024 controls were included in the study. Of the patients, 3,029 (35%) had moderate to severe TBI. The cumulative incidence of epilepsy in the TBI group was 3.1% (95% Confidence Interval [CI] 2.8–3.5%) after 2 years and 4.0% (3.6–4.5%) after 5 years. Corresponding cumulative incidences in the control group were 0.2% (95% CI 0.2–0.3%) and 0.5% (0.5–0.6%). The highest incidence was observed in patients with severe TBI according to AIS (11.8% [95% CI 9.7–14.4%] after 2 years and 13.2% [10.8–16.0%] after 5 years) and in patients >40 years of age.ConclusionPatients with TBI have significantly higher risk of developing epilepsy compared to population controls. However, PTE incidence following moderate–severe TBI was notably lower than what has been reported in several previously published studies
The velocity distribution of nearby stars from Hipparcos data II. The nature of the low-velocity moving groups
The velocity distribution of nearby stars contains many "moving groups" that
are inconsistent with the standard assumption of an axisymmetric,
time-independent, and steady-state Galaxy. We study the age and metallicity
properties of the low-velocity moving groups based on the reconstruction of the
local velocity distribution in Paper I of this series. We perform stringent,
conservative hypothesis testing to establish for each of these moving groups
whether it could conceivably consist of a coeval population of stars. We
conclude that they do not: the moving groups are not trivially associated with
their eponymous open clusters nor with any other inhomogeneous star formation
event. Concerning a possible dynamical origin of the moving groups, we test
whether any of the moving groups has a higher or lower metallicity than the
background population of thin disk stars, as would generically be the case if
the moving groups are associated with resonances of the bar or spiral
structure. We find clear evidence that the Hyades moving group has higher than
average metallicity and weak evidence that the Sirius moving group has lower
than average metallicity, which could indicate that these two groups are
related to the inner Lindblad resonance of the spiral structure. Further we
find weak evidence that the Hercules moving group has higher than average
metallicity, as would be the case if it is associated with the bar's outer
Lindblad resonance. The Pleiades moving group shows no clear metallicity
anomaly, arguing against a common dynamical origin for the Hyades and Pleiades
groups. Overall, however, the moving groups are barely distinguishable from the
background population of stars, raising the likelihood that the moving groups
are associated with transient perturbations. [abridged
The Color Variability of Quasars
We quantify quasar color-variability using an unprecedented variability
database - ugriz photometry of 9093 quasars from SDSS Stripe 82, observed over
8 years at ~60 epochs each. We confirm previous reports that quasars become
bluer when brightening. We find a redshift dependence of this blueing in a
given set of bands (e.g. g and r), but show that it is the result of the flux
contribution from less-variable or delayed emission lines in the different SDSS
bands at different redshifts. After correcting for this effect, quasar
color-variability is remarkably uniform, and independent not only of redshift,
but also of quasar luminosity and black hole mass. The color variations of
individual quasars, as they vary in brightness on year timescales, are much
more pronounced than the ranges in color seen in samples of quasars across many
orders of magnitude in luminosity. This indicates distinct physical mechanisms
behind quasar variability and the observed range of quasar luminosities at a
given black hole mass - quasar variations cannot be explained by changes in the
mean accretion rate. We do find some dependence of the color variability on the
characteristics of the flux variations themselves, with fast, low-amplitude,
brightness variations producing more color variability. The observed behavior
could arise if quasar variability results from flares or ephemeral hot spots in
an accretion disc.Comment: Accepted for publication in ApJ - in press, 17 pages, 14 figures -
v2: abstract typo corrected & reference clean-u
Think Outside the Color Box: Probabilistic Target Selection and the SDSS-XDQSO Quasar Targeting Catalog
We present the SDSS-XDQSO quasar targeting catalog for efficient flux-based
quasar target selection down to the faint limit of the Sloan Digital Sky Survey
(SDSS) catalog, even at medium redshifts (2.5 <~ z <~ 3) where the stellar
contamination is significant. We build models of the distributions of stars and
quasars in flux space down to the flux limit by applying the
extreme-deconvolution method to estimate the underlying density. We convolve
this density with the flux uncertainties when evaluating the probability that
an object is a quasar. This approach results in a targeting algorithm that is
more principled, more efficient, and faster than other similar methods. We
apply the algorithm to derive low-redshift (z < 2.2), medium-redshift (2.2 <= z
3.5) quasar probabilities for all 160,904,060
point sources with dereddened i-band magnitude between 17.75 and 22.45 mag in
the 14,555 deg^2 of imaging from SDSS Data Release 8. The catalog can be used
to define a uniformly selected and efficient low- or medium-redshift quasar
survey, such as that needed for the SDSS-III's Baryon Oscillation Spectroscopic
Survey project. We show that the XDQSO technique performs as well as the
current best photometric quasar-selection technique at low redshift, and
outperforms all other flux-based methods for selecting the medium-redshift
quasars of our primary interest. We make code to reproduce the XDQSO quasar
target selection publicly available
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