506 research outputs found

    A novel streamlined trauma response team training improves imaging efficiency for pediatric blunt abdominal trauma patients

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    Background/purpose The morbidity and mortality of children with traumatic injuries are directly related to the time to definitive management of their injuries. Imaging studies are used in the trauma evaluation to determine the injury type and severity. The goal of this project is to determine if a formal streamlined trauma response improves efficiency in pediatric blunt trauma by evaluating time to acquisition of imaging studies and definitive management. Methods This study is a chart review of patients < 18 years who presented to a pediatric trauma center following blunt trauma requiring trauma team activation. 413 records were reviewed to determine if training changed the efficiency of CT acquisition and 652 were evaluated for FAST efficiency. The metrics used for comparison were time from ED arrival to CT image, FAST, and disposition. Results Time from arrival to CT acquisition decreased from 37 (SD 23) to 28 (SD27) min (p < 0.05) after implementation. The proportion of FAST scans increased from 315 (63.5%) to 337 (80.8%) and the time to FAST decreased from 18 (SD15) to 8 (SD10) min (p < 0.05). The time to operating room (OR) decreased after implementation. Conclusion The implementation of a streamlined trauma team approach is associated with both decreased time to CT, FAST, OR, and an increased proportion of FAST scans in the pediatric trauma evaluation. This could result in the rapid identification of injuries, faster disposition from the ED, and potentially improve outcomes in bluntly injured children

    Scarred Patterns in Surface Waves

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    Surface wave patterns are investigated experimentally in a system geometry that has become a paradigm of quantum chaos: the stadium billiard. Linear waves in bounded geometries for which classical ray trajectories are chaotic are known to give rise to scarred patterns. Here, we utilize parametrically forced surface waves (Faraday waves), which become progressively nonlinear beyond the wave instability threshold, to investigate the subtle interplay between boundaries and nonlinearity. Only a subset (three main types) of the computed linear modes of the stadium are observed in a systematic scan. These correspond to modes in which the wave amplitudes are strongly enhanced along paths corresponding to certain periodic ray orbits. Many other modes are found to be suppressed, in general agreement with a prediction by Agam and Altshuler based on boundary dissipation and the Lyapunov exponent of the associated orbit. Spatially asymmetric or disordered (but time-independent) patterns are also found even near onset. As the driving acceleration is increased, the time-independent scarred patterns persist, but in some cases transitions between modes are noted. The onset of spatiotemporal chaos at higher forcing amplitude often involves a nonperiodic oscillation between spatially ordered and disordered states. We characterize this phenomenon using the concept of pattern entropy. The rate of change of the patterns is found to be reduced as the state passes temporarily near the ordered configurations of lower entropy. We also report complex but highly symmetric (time-independent) patterns far above onset in the regime that is normally chaotic.Comment: 9 pages, 10 figures (low resolution gif files). Updated and added references and text. For high resolution images: http://physics.clarku.edu/~akudrolli/stadium.htm

    Amplitude equations and pattern selection in Faraday waves

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    We present a systematic nonlinear theory of pattern selection for parametric surface waves (Faraday waves), not restricted to fluids of low viscosity. A standing wave amplitude equation is derived from the Navier-Stokes equations that is of gradient form. The associated Lyapunov function is calculated for different regular patterns to determine the selected pattern near threshold. For fluids of large viscosity, the selected wave pattern consists of parallel stripes. At lower viscosity, patterns of square symmetry are obtained in the capillary regime (large frequencies). At lower frequencies (the mixed gravity-capillary regime), a sequence of six-fold (hexagonal), eight-fold, ... patterns are predicted. The regions of stability of the various patterns are in quantitative agreement with recent experiments conducted in large aspect ratio systems.Comment: 12 pages, 1 figure, Revte

    Fault-tolerant protection of near-term trapped-ion topological qubits under realistic noise sources

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    The quest of demonstrating beneficial quantum error correction in near-term noisy quantum processors can benefit enormously from a low-resource optimization of fault-tolerant schemes, which are specially designed for a particular platform considering both state-of-the-art technological capabilities and main sources of noise. In this work, we show that flag-qubit-based fault-tolerant techniques for active error detection and correction, as well as for encoding of logical qubits, can be leveraged in current designs of trapped-ion quantum processors to achieve this break-even point of beneficial quantum error correction. Our improved description of the relevant sources of noise, together with detailed schedules for the implementation of these flag-based protocols, provide one of the most complete microscopic characterizations of a fault-tolerant quantum processor to date. By extensive numerical simulations, we provide a comparative study of flag- and cat-based approaches to quantum error correction, and show that the superior performance of the former can become a landmark in the success of near-term quantum computing with noisy trapped-ion devices.Comment: new version, accepted in Phys. Rev.

    Asymmetric gap soliton modes in diatomic lattices with cubic and quartic nonlinearity

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    Nonlinear localized excitations in one-dimensional diatomic lattices with cubic and quartic nonlinearity are considered analytically by a quasi-discreteness approach. The criteria for the occurence of asymmetric gap solitons (with vibrating frequency lying in the gap of phonon bands) and small-amplitude, asymmetric intrinsic localized modes (with the vibrating frequency being above all the phonon bands) are obtained explicitly based on the modulational instabilities of corresponding linear lattice plane waves. The expressions of particle displacement for all these nonlinear localized excitations are also given. The result is applied to standard two-body potentials of the Toda, Born-Mayer-Coulomb, Lennard-Jones, and Morse type. The comparison with previous numerical study of the anharmonic gap modes in diatomic lattices for the standard two-body potentials is made and good agreement is found.Comment: 24 pages in Revtex, 2 PS figure

    Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

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    We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above 5×1065\times 10^{6} GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above 10610^{6} GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between 5×1065 \times 10^{6} and 5×10105 \times 10^{10} GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm GeV}/{\rm cm}^2\ \sec\ {\rm sr}at at 10^9\ {\rm GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.Comment: The version accepted for publication in Physical Review
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