26,110 research outputs found
Characterizing the Risk Profiles of Intensive Care Units
OBJECTIVE: To develop a new method to evaluate the performance of individual ICUs through the calculation and visualisation of risk profiles.
METHODS: The study included 102,561 patients consecutively admitted to 77 ICUs in Austria. We customized the function which predicts hospital mortality (using SAPS II) for each ICU. We then compared the risks of hospital mortality resulting from this function with the risks which would be obtained using the original function. The derived risk ratio was then plotted together with point-wise confidence intervals in order to visualise the individual risk profile of each ICU over the whole spectrum of expected hospital mortality.
MAIN MEASUREMENTS AND RESULTS: We calculated risk profiles for all ICUs in the ASDI data set according to the proposed method. We show examples how the clinical performance of ICUs may depend on the severity of illness of their patients. Both the distribution of the Hosmer-Lemeshow goodness-of-fit test statistics and the histogram of the corresponding P values demonstrated a good fit of the individual risk models.
CONCLUSIONS: Our risk profile model makes it possible to evaluate ICUs on the basis of the specific risk for patients to die compared to a reference sample over the whole spectrum of hospital mortality. Thus, ICUs at different levels of severity of illness can be directly compared, giving a clear advantage over the use of the conventional single point estimate of the overall observed-to-expected mortality ratio
Six New Galactic Orbits of Globular Clusters in a Milky-Way-Like Galaxy
Absolute proper motions for six new globular clusters have recently been
determined. This motivated us to obtain the Galactic orbits of these six
clusters both in an axisymmetric Galactic potential and in a barred potential,
such as the one of our Galaxy. Orbits are also obtained for a Galactic
potential that includes spiral arms. The orbital characteristics are compared
and discussed for these three cases. Tidal radii and destruction rates are also
computed and discussed.Comment: 29 pages, 11 figures. Accepted for publication in Ap
Gamow-Teller strength distributions in Xe isotopes
The energy distributions of the Gamow-Teller strength are studied for
even-even Xe isotopes with mass numbers from 124 to 142. A self-consistent
microscopic formalism is used to generate the single particle basis, using a
deformed Skyrme Hartree-Fock mean field with pairing correlations in BCS
approximation. The Gamow-Teller transitions are obtained within a quasiparticle
random phase approximation (QRPA) approach using a residual spin-isospin
interaction in the particle-hole and particle-particle channels. We then
discuss the pairing BCS treatment and the determination of the ph and pp
residual interaction coupling constants. We study the GT+ and GT- strength
distributions for the equilibrium nuclear shapes, which are an essential
information for studies of charge-exchange reactions and double-beta processes
involving these isotopes.Comment: 15 pages, 5 figures. To appear in Phys Rev
Cascade Failure in a Phase Model of Power Grids
We propose a phase model to study cascade failure in power grids composed of
generators and loads. If the power demand is below a critical value, the model
system of power grids maintains the standard frequency by feedback control. On
the other hand, if the power demand exceeds the critical value, an electric
failure occurs via step out (loss of synchronization) or voltage collapse. The
two failures are incorporated as two removal rules of generator nodes and load
nodes. We perform direct numerical simulation of the phase model on a
scale-free network and compare the results with a mean-field approximation.Comment: 7 pages, 2 figure
Relativistically extended Blanchard recurrence relation for hydrogenic matrix elements
General recurrence relations for arbitrary non-diagonal, radial hydrogenic
matrix elements are derived in Dirac relativistic quantum mechanics. Our
approach is based on a generalization of the second hypervirial method
previously employed in the non-relativistic Schr\"odinger case. A relativistic
version of the Pasternack-Sternheimer relation is thence obtained in the
diagonal (i.e. total angular momentum and parity the same) case, from such
relation an expression for the relativistic virial theorem is deduced. To
contribute to the utility of the relations, explicit expressions for the radial
matrix elements of functions of the form and
---where is a Dirac matrix--- are presented.Comment: 21 pages, to be published in J. Phys. B: At. Mol. Opt. Phys. in Apri
Resultados iniciais das propriedades tecnológicas da borracha natural crua dos novos clones de seringueira da série IAC 400.
A qualidade da borracha natural dos novos clones da serie IAC 300 para recomendação ao plantio no estado de São Paulo (fase final).
Estudo preliminar da mastigação e da coagulação nas propriedades tecnológicas da borracha natural crua de clones da série IAC.
Avaliação inicial das propriedades tecnológicas da borracha natural de novos clones da Série IAC 300.
Quarkonia production with the Hera-B experiment
Measurements of the dependence of the J/Psi production cross section on its
kinematic variables as well as on the target atomic numbers for 920 GeV/c
protons incident on different targets have been made with the Hera-B detector.
The large collected di-lepton sample allows to study the production ratio of
Psi(2S) to J/Psi and of Chic to J/Psi . We also report on measurements of the
b-bbar and Upsilon production cross section.Comment: 9 pages, 11 figure
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