1,551 research outputs found
Identifying Patients Suitable for Discharge After a Single-Presentation High-Sensitivity Troponin Result: A Comparison of Five Established Risk Scores and Two High-Sensitivity Assays.
STUDY OBJECTIVE: We compare the ability of 5 established risk scores to identify patients with suspected acute coronary syndromes who are suitable for discharge after a modified single-presentation high-sensitivity troponin result. METHODS: This was a prospective observational study conducted in a UK district general hospital emergency department. Consecutive adults recruited with suspected acute coronary syndrome for whom attending physicians determined evaluation with serial troponin testing was required. Index tests were definitions of low risk applied to modified Goldman, Thrombolysis in Myocardial Infarction (TIMI), Global Registry of Acute Cardiac Events (GRACE), History, ECG, Age, Risk Factors, Troponin (HEART), and Vancouver Chest Pain Rule risk scores, incorporating either high-sensitivity troponin T or I results. The endpoint was acute myocardial infarction within 30 days. A test sensitivity threshold for acute myocardial infarction of 98% was chosen. Clinical utility was defined as a negative predictive value greater than or equal to 99.5% and identification of greater than 30% suitable for discharge. RESULTS: Nine hundred fifty-nine patients underwent high-sensitivity troponin T analysis and 867 underwent high-sensitivity troponin I analysis. In the high-sensitivity troponin T group, 79 of 959 (8.2%) had an acute myocardial infarction and 66 of 867 (7.6%) in the high-sensitivity troponin I group. Two risk scores (GRACE <80 and HEART ≤3) did not have the potential to achieve a sensitivity of 98% with high-sensitivity troponin T, and 3 scores (Goldman ≤1, TIMI ≤1, and GRACE <80) with high-sensitivity troponin I. A TIMI score of 0 or less than or equal to 1 and modified Goldman score less than or equal to 1 with high-sensitivity troponin T, and TIMI score of 0 and HEART score of less than or equal to 3 with high-sensitivity troponin I had the potential to achieve a negative predictive value greater than or equal to 99.5% while identifying greater than 30% of patients as suitable for immediate discharge. CONCLUSION: With established risk scores, it may be possible to identify greater than 30% of patients suitable for discharge, with a negative predictive value greater than or equal to 99.5% for the diagnosis of acute myocardial infarction, using a single high-sensitivity troponin test result at presentation. There is variation in high-sensitivity troponin assays, which may have implications in introducing rapid rule-out protocols
Psychosocial outcomes of an inclusive adapted sport and adventurous training course for military personnel.
PURPOSE: To explore the psychosocial outcomes of an inclusive adapted sport and adventurous training course that aims to support the rehabilitation and personal development of military personnel who have sustained physical and/or psychological disability. METHOD: Narrative life story interviews were conducted with 11 men aged 20-43 taking part in one of the 5-day courses. A thematic narrative analysis was conducted, focusing on accounts that provided insights into personally meaningful psychosocial outcomes of the course. FINDINGS: We identified six themes, falling into two distinct clusters. "Bringing me back to myself" was achieved through the themes of (1) returning to activity, (2) rediscovering a sense of purpose, and (3) reconnecting to others. "New rooms to explore" was realised through (4) experiencing new activities, (5) being valued/respected/cared for and (6) being inspired by other people. CONCLUSION: Involvement in the course stimulated a balance of present- and future-oriented psychosocial outcomes through which participants both recreated aspects of themselves that had been lost through injury/trauma and moved forward with their lives as a result of new horizons of possibility. IMPLICATIONS FOR REHABILITATION: This 5-day inclusive adapted sport and adventurous training course offered meaningful psychosocial outcomes among military personnel who had experienced physical and/or psychological disability. The course helped participants recover aspects of their previous life and self through becoming physically active again, rediscovering a sense of purpose and reconnecting to others. Participants describe a broadening of life horizons as a result of the course, through new activities, being valued/respected/cared for, and being inspired by other people
Reversible quantum operations and their application to teleportation
Quantum operations provide a general description of the state changes allowed
by quantum mechanics. Simple necessary and sufficient conditions for an ideal
quantum operation to be reversible by a unitary operation are derived in this
paper. These results generalize recent work on reversible measurements by
Mabuchi and Zoller [Phys. Rev. Lett. {\bf 76}, 3108 (1996)]. Quantum
teleportation can be understood as a special case of the problem of reversing
quantum operations. We characterize completely teleportation schemes of the
type proposed by Bennett {\it et al.} [Phys. Rev. Lett. {\bf 70}, 1895 (1993)].Comment: 10 pages, Revte
Hypersensitivity to Perturbations in the Quantum Baker's Map
We analyze a randomly perturbed quantum version of the baker's
transformation, a prototype of an area-conserving chaotic map. By numerically
simulating the perturbed evolution, we estimate the information needed to
follow a perturbed Hilbert-space vector in time. We find that the Landauer
erasure cost associated with this information grows very rapidly and becomes
much larger than the maximum statistical entropy given by the logarithm of the
dimension of Hilbert space. The quantum baker's map thus displays a
hypersensitivity to perturbations that is analogous to behavior found earlier
in the classical case. This hypersensitivity characterizes ``quantum chaos'' in
a way that is directly relevant to statistical physics.Comment: 8 pages, LATEX, 3 Postscript figures appended as uuencoded fil
Qubit metrology and decoherence
Quantum properties of the probes used to estimate a classical parameter can
be used to attain accuracies that beat the standard quantum limit. When qubits
are used to construct a quantum probe, it is known that initializing qubits
in an entangled "cat state," rather than in a separable state, can improve the
measurement uncertainty by a factor of . We investigate how the
measurement uncertainty is affected when the individual qubits in a probe are
subjected to decoherence. In the face of such decoherence, we regard the rate
at which qubits can be generated and the total duration of a
measurement as fixed resources, and we determine the optimal use of
entanglement among the qubits and the resulting optimal measurement uncertainty
as functions of and .Comment: 24 Pages, 3 Figure
Direct Neutron Capture for Magic-Shell Nuclei
In neutron capture for magic--shell nuclei the direct reaction mechanism can
be important and may even dominate. As an example we investigated the reaction
Ca(n,Ca for projectile energies below 250\,keV in a direct
capture model using the folding procedure for optical and bound state
potentials. The obtained theoretical cross sections are in agreement with the
experimental data showing the dominance of the direct reaction mechanism in
this case. The above method was also used to calculate the cross section for
Ca(n,Ca.Comment: REVTeX, 7 pages plus 3 uuencoded figures, the complete uuencoded
postscript file is available at ftp://is1.kph.tuwien.ac.at/pub/ohu/calcium.u
Quantum Bayes rule
We state a quantum version of Bayes's rule for statistical inference and give
a simple general derivation within the framework of generalized measurements.
The rule can be applied to measurements on N copies of a system if the initial
state of the N copies is exchangeable. As an illustration, we apply the rule to
N qubits. Finally, we show that quantum state estimates derived via the
principle of maximum entropy are fundamentally different from those obtained
via the quantum Bayes rule.Comment: REVTEX, 9 page
Hubble Space Telescope Evidence for an Intermediate-Mass Black Hole in the Globular Cluster M15: II. Kinematical Analysis and Dynamical Modeling
We analyze HST/STIS spectra (see Paper I) of the central region of the dense
globular cluster M15. We infer the velocities of 64 individual stars,
two-thirds of which have their velocity measured for the first time. This
triples the number of stars with measured velocities in the central 1 arcsec of
M15 and doubles the number in the central 2 arcsec. Combined with existing
ground-based data we obtain the radial profiles of the projected kinematical
quantities. The RMS velocity sigma_RMS rises to 14 km/s in the central few
arcsec, somewhat higher than the values of 10-12 km/s inferred previously from
ground-based data. To interpret the results we construct dynamical models based
on the Jeans equation, which imply that M15 must have a central concentration
of non-luminous material. If this is due to a single black hole, then its mass
is M_BH = (3.9 +/- 2.2) x 10^3 solar masses. This is consistent with the
relation between M_BH and sigma_RMS that has been established for galaxies.
Also, the existence of intermediate-mass black holes in globular clusters is
consistent with several scenarios for globular cluster evolution proposed in
the literature. Therefore, these results may have important implications for
our understanding of the evolution of globular clusters, the growth of black
holes, the connection between globular cluster and galaxy formation, and the
nature of the recently discovered `ultra-luminous' X-ray sources in nearby
galaxies. Instead of a single black hole, M15 could have a central
concentration of dark remnants (e.g., neutron stars) due to mass segregation.
However, the best-fitting Fokker-Planck models that have previously been
constructed for M15 do not predict a central mass concentration that is
sufficient to explain the observed kinematics.[ABRIDGED]Comment: 43 pages, LaTeX, with 14 PostScript figures. Astronomical Journal, in
press (Dec 2002). Please note that the results reported here are modified by
the Addendum available at astro-ph/0210158 (Astronomical Journal, in press,
Jan 2003). This second version submitted to astro-ph is identical to first,
with the exception of the preceeding remar
Planning Considerations for a Mars Sample Receiving Facility: Summary and Interpretation of Three Design Studies
It has been widely understood for many years that an essential component of a Mars Sample Return mission is a Sample Receiving Facility (SRF). The purpose of such a facility would be to take delivery of the flight hardware that lands on Earth, open the spacecraft and extract the sample container and samples, and conduct an agreed-upon test protocol, while ensuring strict containment and contamination control of the samples while in the SRF. Any samples that are found to be non-hazardous (or are rendered non-hazardous by sterilization) would then be transferred to long-term curation. Although the general concept of an SRF is relatively straightforward, there has been considerable discussion about implementation planning.
The Mars Exploration Program carried out an analysis of the attributes of an SRF to establish its scope, including minimum size and functionality, budgetary requirements (capital cost, operating costs, cost profile), and development schedule. The approach was to arrange for three independent design studies, each led by an architectural design firm, and compare the results. While there were many design elements in common identified by each study team, there were significant differences in the way human operators were to interact with the systems. In aggregate, the design studies provided insight into the attributes of a future SRF and the complex factors to consider for future programmatic planning
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