160 research outputs found
Letter to the Editor regarding the article: "identifying pre-hospital factors associated with outcome for major trauma patients in a regional trauma network: An exploratory study"
The aim of this Letter to the Editor was to report some methodological shortcomings in a recently published article. Issues regarding missing values and overfitting are mentioned. First, Complete Case (CC) analysis was used instead of an imputation method. Second, there was a high chance of overfitting and lack of model validation. In conclusion, the results of this study should be interpret with caution and further research is necessary
The volume-outcome relationship for hip fractures: a systematic review and meta-analysis of 2,023,469 patients
Background and purpose — It has been hypothesized
that hospitals and surgeons with high caseloads of hip fracture patients have better outcomes, but empirical studies
have reported contradictory results. This systematic review
and meta-analysis evaluates the volume–outcome relationship among patients with hip fracture patients.
Methods — A search of different databases was performed up to February 2018. Selection of relevant studies,
data extraction, and critical appraisal of the methodological
quality was performed by 2 independent reviewers. A random-effects meta-analysis using studies with comparative
cut-offs was performed to estimate the effect of hospital and
surgeon volume on outcome, defined as in-hospital mortality
and postoperative complications.
Results — 24 studies comprising 2,023,469 patients
were included. Overall, the quality was reasonable. 11 studies reported better health outcomes in high-volume centers
and 2 studies reported better health outcomes in low-volume
centers. In the meta-analysis of 11 studies there was a statistically non-significant association between higher hospital
volume and both lower in-hospital mortality (adjusted odds
ratio (aOR) 0.87, 95% confidence interval (CI) 0.73–1.04)
and fewer postoperative complications (aOR 0.87, CI 0.75–
1.02). Four studies on surgeon volume were included in
the meta-analysis and showed a minor association between
higher surgeon volume and in-hospital mortality (aOR 0.92,
CI 0.76–1.12).
Interpretation — This systematic review and metaanalysis did not find an evident effect of hospital or surgeon
volume on health outcomes. Future research without volume
cut-offs is needed to examine whether a true volume–outcome relationship exists
Magnetoluminescence
Pulsar Wind Nebulae, Blazars, Gamma Ray Bursts and Magnetars all contain
regions where the electromagnetic energy density greatly exceeds the plasma
energy density. These sources exhibit dramatic flaring activity where the
electromagnetic energy distributed over large volumes, appears to be converted
efficiently into high energy particles and gamma-rays. We call this general
process magnetoluminescence. Global requirements on the underlying, extreme
particle acceleration processes are described and the likely importance of
relativistic beaming in enhancing the observed radiation from a flare is
emphasized. Recent research on fluid descriptions of unstable electromagnetic
configurations are summarized and progress on the associated kinetic
simulations that are needed to account for the acceleration and radiation is
discussed. Future observational, simulation and experimental opportunities are
briefly summarized.Comment: To appear in "Jets and Winds in Pulsar Wind Nebulae, Gamma-ray Bursts
and Blazars: Physics of Extreme Energy Release" of the Space Science Reviews
serie
The volume-outcome relationship in severely injured patients: A systematic review and meta-analysis
BACKGROUND The volume-outcome relationship in severely injured patients remains under debate and this has consequences for the designation of trauma centers. OBJECTIVES The aim of this study was to evaluate the relationship between hospital or surgeon volume and health outcomes in severely injured patients. METHODS Six electronic databases were searched from 1980 up to January 30, 2018, to identify studies that describe the relationship between hospital or surgeon volume and health outcomes in severely injured patients (preferably Injury Severity Score above 15). Selection of relevant studies, data extraction, and critical appraisal of the methodological quality were performed by two independent reviewers. Pooled adjusted and unadjusted estimates of the effect of volume on in-hospital mortality, only in study populations with Injury Severity Score greater than 15, were calculated with a random-effects meta-analysis. A mixed effects linear regression model was used to assess hospital volume as continuous parameter. RESULTS Eighteen observational cohort studies were included. The majority (13 [72%] of 18) reported an association between higher hospital or surgeon volume and lower mortality rate. Overall, the quality of the included studies was reasonable, with insufficient adjustment as one of the most common limitations. Eight studies were included in the meta-analysis with a total of 222,418 patients. High hospital volume (>240 admitted severely injured patients per year) was associated with a lower risk of mortality (adjusted odds ratio, 0.85; 95% confidence interval, 0.76-0.94). Four studies were included in the regression model, providing a beta of-0.17 per 10 patients (95% CI,-0.27 to-0.07). There was no clear association between surgeon volume and mortality rates based on three available studies. CONCLUSION Our systematic overview of the literature reveals a modest association between high-volume centers and lower mortality in severely injured patients, suggesting that designation of high-volume centers might improve outcomes among severely injured patients
Recurrence of Dupuytren’s contracture: A consensus-based definition
Purpose: One of the major determinants of Dupyutren disease (DD) treatment efficacy is recurrence of the contracture. Unfortunately, lack of agreement in the literature on what constitutes recurrence makes it nearly impossible to compare the multiple treatments alternatives available today. The aim of this study is to bring an unbiased pool of experts to agree upon what would be considered a recurrence of DD after treatment; and from that consensus establish a much-needed definition for DD recurrence. Methods: To reach an expert consensus on the definition of recurrence we used the Delphi method and invited 43 Dupuytren’s research and treatment experts from 10 countries to participate by answering a series of questionnaire rounds. After each round the answers were analyzed and the experts received a feedback report with another questionnaire round to further hone in of the definition. We defined consensus when at least 70% of the experts agreed on a topic. Results: Twenty-one experts agreed to participate in this study. After four consensus rounds, we agreed that DD recurrence should be defined as “more than 20 degrees of contracture recurrence in any treated joint at one year post-treatment compared to six weeks post-treatment”. In addition, “recurrence should be reported individually for every treated joint” and afterwards measurements should be repeated and reported yearly. Conclusion: This study provides the most comprehensive to date definition of what should be considered recurrence of DD. These standardized criteria should allow us to better evaluate the many treatment alternatives
Metal enrichment processes
There are many processes that can transport gas from the galaxies to their
environment and enrich the environment in this way with metals. These metal
enrichment processes have a large influence on the evolution of both the
galaxies and their environment. Various processes can contribute to the gas
transfer: ram-pressure stripping, galactic winds, AGN outflows, galaxy-galaxy
interactions and others. We review their observational evidence, corresponding
simulations, their efficiencies, and their time scales as far as they are known
to date. It seems that all processes can contribute to the enrichment. There is
not a single process that always dominates the enrichment, because the
efficiencies of the processes vary strongly with galaxy and environmental
properties.Comment: 18 pages, 8 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 17; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Is (poly-) substance use associated with impaired inhibitory control? A mega-analysis controlling for confounders
Dilepton mass spectra in p+p collisions at sqrt(s)= 200 GeV and the contribution from open charm
The PHENIX experiement has measured the electron-positron pair mass spectrum
from 0 to 8 GeV/c^2 in p+p collisions at sqrt(s)=200 GeV. The contributions
from light meson decays to e^+e^- pairs have been determined based on
measurements of hadron production cross sections by PHENIX. They account for
nearly all e^+e^- pairs in the mass region below 1 GeV/c^2. The e^+e^- pair
yield remaining after subtracting these contributions is dominated by
semileptonic decays of charmed hadrons correlated through flavor conservation.
Using the spectral shape predicted by PYTHIA, we estimate the charm production
cross section to be 544 +/- 39(stat) +/- 142(syst) +/- 200(model) \mu b, which
is consistent with QCD calculations and measurements of single leptons by
PHENIX.Comment: 375 authors from 57 institutions, 18 pages, 4 figures, 2 tables.
Submitted to Physics Letters B. v2 fixes technical errors in matching authors
to institutions. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Inclusive cross section and double helicity asymmetry for \pi^0 production in p+p collisions at sqrt(s)=200 GeV: Implications for the polarized gluon distribution in the proton
The PHENIX experiment presents results from the RHIC 2005 run with polarized
proton collisions at sqrt(s)=200 GeV, for inclusive \pi^0 production at
mid-rapidity. Unpolarized cross section results are given for transverse
momenta p_T=0.5 to 20 GeV/c, extending the range of published data to both
lower and higher p_T. The cross section is described well for p_T < 1 GeV/c by
an exponential in p_T, and, for p_T > 2 GeV/c, by perturbative QCD. Double
helicity asymmetries A_LL are presented based on a factor of five improvement
in uncertainties as compared to previously published results, due to both an
improved beam polarization of 50%, and to higher integrated luminosity. These
measurements are sensitive to the gluon polarization in the proton, and exclude
maximal values for the gluon polarization.Comment: 375 authors, 7 pages, 3 figures. Submitted to Phys. Rev. D, Rapid
Communications. Plain text data tables for the points plotted in figures for
this and previous PHENIX publications are (or will be) publicly available at
http://www.phenix.bnl.gov/papers.htm
Measurement of high-p_T Single Electrons from Heavy-Flavor Decays in p+p Collisions at sqrt(s) = 200 GeV
The momentum distribution of electrons from decays of heavy flavor (charm and
beauty) for midrapidity |y| < 0.35 in p+p collisions at sqrt(s) = 200 GeV has
been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider
(RHIC) over the transverse momentum range 0.3 < p_T < 9 GeV/c. Two independent
methods have been used to determine the heavy flavor yields, and the results
are in good agreement with each other. A fixed-order-plus-next-to-leading-log
pQCD calculation agrees with the data within the theoretical and experimental
uncertainties, with the data/theory ratio of 1.72 +/- 0.02^stat +/- 0.19^sys
for 0.3 < p_T < 9 GeV/c. The total charm production cross section at this
energy has also been deduced to be sigma_(c c^bar) = 567 +/- 57^stat +/-
224^sys micro barns.Comment: 375 authors from 57 institutions, 6 pages, 3 figures. Submitted to
Physical Review Letters. Plain text data tables for the points plotted in
figures for this and previous PHENIX publications are (or will be) publicly
available at http://www.phenix.bnl.gov/papers.htm
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