722 research outputs found
Modeling and prediction of surgical procedure times
Accurate prediction of medical operation times is of crucial importance for cost efficient operation room planning in hospitals. This paper investigates the possible dependence of procedure times on surgeon factors like age, experience, gender, and team composition. The effect of these factors is estimated for over 30 different types of medical operations in two hospitals, by means of ANOVA models for logarithmic case durations. The estimation data set contains about 30,000 observations from 2005 till 2008. The relevance of surgeon factors depends on the type of operation. The factors found most often to be significant are team composition, experience, and daytime. Contrary to widespread opinions among surgeons, gender has nearly never a significant effect. By incorporating surgeon factors, the accuracy of out-of-sample prediction of case durations of about 1,250 surgical operations in 2009 is improved by up to more than 15 percent as compared to current planning procedures.planning;ANOVA model;European hospital;current procedure terminology (CPT);health care management;lognormal distribution;operation room;surgeon factors
Humans in Space: Summarizing the Medico-Biological Results of the Space Shuttle Program
As we celebrate the 50th anniversary of Gagarin's flight that opened the era of Humans in Space we also commemorate the 30th anniversary of the Space Shuttle Program (SSP) which was triumphantly completed by the flight of STS-135 on July 21, 2011. These were great milestones in the history of Human Space Exploration. Many important questions regarding the ability of humans to adapt and function in space were answered for the past 50 years and many lessons have been learned. Significant contribution to answering these questions was made by the SSP. To ensure the availability of the Shuttle Program experiences to the international space community NASA has made a decision to summarize the medico-biological results of the SSP in a fundamental edition that is scheduled to be completed by the end of 2011 beginning 2012. The goal of this edition is to define the normal responses of the major physiological systems to short-duration space flights and provide a comprehensive source of information for planning, ensuring successful operational activities and for management of potential medical problems that might arise during future long-term space missions. The book includes the following sections: 1. History of Shuttle Biomedical Research and Operations; 2. Medical Operations Overview Systems, Monitoring, and Care; 3. Biomedical Research Overview; 4. System-specific Adaptations/Responses, Issues, and Countermeasures; 5. Multisystem Issues and Countermeasures. In addition, selected operational documents will be presented in the appendices. The chapters are written by well-recognized experts in appropriate fields, peer reviewed, and edited by physicians and scientists with extensive expertise in space medical operations and space-related biomedical research. As Space Exploration continues the major question whether humans are capable of adapting to long term presence and adequate functioning in space habitats remains to be answered We expect that the comprehensive review of the medico-biological results of the SSP along with the data collected during the missions on the space stations (Mir and ISS) provides a good starting point in seeking the answer to this question
Anisotropy in the pion angular distribution of the reaction pp -> pp pi0 at 400 MeV
The reaction pp -> pp pi0 was studied with the WASA detector at the CELSIUS
storage ring. The center of mass angular distribution of the pi0 was obtained
by detection of the gamma decay products together with the two outgoing
protons, and found to be anisotropic with a negative second derivative slope,
in agreement with the theoretical predictions from a microscopic calculation.Comment: Revtex 4 style, 5 pages 7 figures, PACS numbers:13.60.Le, 13.75.Cs,
21.45.+v, 25.10.+
A method to disentangle single- and multi-meson production in missing mass spectra from quasi-free pn --> pn X reactions
The separation of contributions from multi- and single-meson production in
the missing mass spectrum of the quasi-free pn --> pnX reaction constitutes
a~challenging task when the reaction is studied close to threshold. This is
especially true if the resolution of the mass determination is comparable with
the excess energy and if the investigated signal appears close to the
kinematical limit. In this article we outline a method which permits the
extraction of the signal originating from the creation of a single meson
without the necessity of conducting model-dependent simulations. For the pd -->
pnXp(spectator) reactions, the method allows one to combine events
corresponding to multi-meson production at various excess energies with respect
to the pn --> pn meson process, and hence leads to an increase of the
statistics needed for the determination of the shape of the multi-meson
background.
As an example of the application of the method, we demonstrate that the
evaluation of the data from the pd --> pnXp(sp) process according to the
described technique enables one to extract a signal of the pn --> pn eta
reaction whose shape is consistent with expectations, supporting the
correctness and usefulness of the method introduced.Comment: 14 pages, 10 figure
Precise 3D track reconstruction algorithm for the ICARUS T600 liquid argon time projection chamber detector
Liquid Argon Time Projection Chamber (LAr TPC) detectors offer charged
particle imaging capability with remarkable spatial resolution. Precise event
reconstruction procedures are critical in order to fully exploit the potential
of this technology. In this paper we present a new, general approach of
three-dimensional reconstruction for the LAr TPC with a practical application
to track reconstruction. The efficiency of the method is evaluated on a sample
of simulated tracks. We present also the application of the method to the
analysis of real data tracks collected during the ICARUS T600 detector
operation with the CNGS neutrino beam.Comment: Submitted to Advances in High Energy Physic
Exclusive Measurements of pp -> dpi+pi0: Double-Pionic Fusion without ABC Effect
Exclusive measurements of the reaction pp -> dpi+pi0 have been carried out at
T_p = 1.1 GeV at the CELSIUS storage ring using the WASA detector. The
isovector pi+pi0 channel exhibits no enhancement at low invariant pipi masses,
i. e. no ABC effect. The differential distributions are in agreement with the
conventional t-channel Delta-Delta excitation process, which also accounts for
the observed energy dependence of the total cross section. This is an update of
a previously published version -- see important note at the end of the article
Double-Pionic Fusion of Nuclear Systems and the ABCEffect -- Aproaching a Puzzle by Exclusive and Kinematically Complete Measurements
The ABC effect - a puzzling low-mass enhancement in the invariant
mass spectrum - is well-known from inclusive measurements of two-pion
production in nuclear fusion reactions. Here we report on first exclusive and
kinematically complete measurements of the most basic double pionic fusion
reaction at 1.03 and 1.35 GeV. The measurements, which
have been carried out at CELSIUS-WASA, reveal the ABC effect to be a
channel phenomenon associated with both a resonance-like
energy dependence in the integral cross section and the formation of a
system in the intermediate state. A corresponding simple
s-channel resonance ansatz provides a surprisingly good description of the
data
Production of eta and 3pi mesons in the pd->3HeX reaction at 1360 and 1450 MeV
The cross sections of the pd -> 3He eta, pd -> 3He pi0 pi0 pi0 and pd -> 3He
pi+ pi- pi0 reactions have been measured at beam kinetic energies T_p= 1360 MeV
and T_p= 1450 MeV using the CELSIUS/WASA detector setup. At both energies, the
differential cross section dsigma/dOmega of the eta meson in the pd -> 3He eta
reaction shows a strong forward-backward asymmetry in the CMS. The ratio
between the pd -> 3He pi+ pi- pi0 and the pd -> 3He pi0 pi0 pi0 cross sections
has been analysed in terms of isospin amplitudes. The reconstructed invariant
mass distributions of the pi-pi, 3He-pi and 3He-2pi systems provide hints on
the role of nucleon resonances in the 3pi production process.Comment: Shorter version accepted to EPJA 10 pages 14 figure
Polarisation of the omega meson in the pd-->3He+omega reaction at 1360 and 1450 MeV
The tensor polarisation of omega mesons produced in the pd-->3He+omega
reaction has been studied at two energies near threshold. The 3He nuclei were
detected in coincidence with the pi0pi+pi- or pi0gamma decay products of the
omega. In contrast to the case of phi meson production, the omega mesons are
found to be unpolarised. This brings into question the applicability of the
Okubo-Zweig-Iizuka rule when comparing the production of vector mesons in low
energy hadronic reactions.Comment: 11 pages, 4 figure
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