3,859 research outputs found

    Risk stratification in non-ST elevation acute coronary syndromes: risk scores, biomarkers and clinical judgment

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    Undifferentiated chest pain is one of the most common reasons for emergency department attendance and admission to hospitals. Non-ST elevation acute coronary syndrome (NSTE-ACS) is an important cause of chest pain, and accurate diagnosis and risk stratification in the emergency department must be a clinical priority. In the future, the incidence of NSTE-ACS will rise further as higher sensitivity troponin assays are implemented in clinical practice. In this article, we review contemporary approaches for the diagnosis and risk stratification of NSTE-ACS during emergency care. We consider the limitations of current practices and potential improvements. Clinical guidelines recommend an early invasive strategy in higher risk NSTE-ACS. The Global Registry of Acute Coronary Events (GRACE) risk score is a validated risk stratification tool which has incremental prognostic value for risk stratification compared with clinical assessment or troponin testing alone. In emergency medicine, there has been a limited adoption of the GRACE score in some countries (e.g. United Kingdom), in part related to a delay in obtaining timely blood biochemistry results. Age makes an exponential contribution to the GRACE score, and on an individual patient basis, the risk of younger patients with a flow-limiting culprit coronary artery lesion may be underestimated. The future incorporation of novel cardiac biomarkers into this diagnostic pathway may allow for earlier treatment stratification. The cost-effectiveness of the new diagnostic pathways based on high-sensitivity troponin and copeptin must also be established. Finally, diagnostic tests and risk scores may optimize patient care but they cannot replace patient-focused good clinical judgment

    Universal Quantum Computation by Scattering in the Fermi-Hubbard Model

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    The Hubbard model may be the simplest model of particles interacting on a lattice, but simulation of its dynamics remains beyond the reach of current numerical methods. In this article, we show that general quantum computations can be encoded into the physics of wave packets propagating through a planar graph, with scattering interactions governed by the fermionic Hubbard model. Therefore, simulating the model on planar graphs is as hard as simulating quantum computation. We give two different arguments, demonstrating that the simulation is difficult both for wave packets prepared as excitations of the fermionic vacuum, and for hole wave packets at filling fraction one-half in the limit of strong coupling. In the latter case, which is described by the t-J model, there is only reflection and no transmission in the scattering events, as would be the case for classical hard spheres. In that sense, the construction provides a quantum mechanical analog of the Fredkin-Toffoli billiard ball computer.Comment: 9 pages, 5 figures. Hyperref and cleveref LaTeX packages conflicted (fixed by including hyperref before cleveref). Other minor edit

    Phase field study of the tip operating state of a freely growing dendrite against convection using a novel parallel multigrid approach

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    Alloy dendrite growth during solidification with coupled thermal-solute-convection fields has been studied by phase field modeling and simulation. The coupled transport equations were solved using a novel parallel-multigrid numerical approach with high computational efficiency that has enabled the investigation of dendrite growth with realistic alloy values of Lewis number ∼104 and Prandtl number ∼10−2. The detailed dendrite tip shape and character were compared with widely recognized analytical approaches to show validity, and shown to be highly dependent on undercooling, solute concentration and Lewis number. In a relatively low flow velocity regime, variations in the ratio of growth selection parameter with and without convection agreed well with theory

    Exploding Aliens and Other Offspring

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    The goal of Exploding Aliens and Other Offspring is to capture my specific surrealist world point of view provided by the closed-knit crazy community I grew up in alongside my love for cartoonish melodrama. The collection progresses in order of images and the evolution of such themes as the venture from childhood to adulthood, societal obligations, religion, parenting, death and the hereafter

    A comparison of secondary successional woody vegetation in two revegetated fields in South Texas and an assessment of habitat use by the olive sparrow, Arremonops rufivirgatus

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    Aspects of plant species composition and structure of two revegetated fields in western Cameron County, Texas, were studied between 1992 and 1995. Avian habitat suitability was assessed using the Olive Sparrow, Arremonops rufivirgatus, as an indicator species. Total vegetation volume at the Longoria Wildlife Management Area (WMA), an area revegetated in 1961, was 0.745 \rm m\sp3V/m\sp2 and that of the Anacua WMA, revegetated in 1983-4, was 0.546 \rm m\sp3V/m\sp2 in 1992. Secondary woody species at the Longoria and Anacua WMA\u27s had a Shannon\u27s index of diversity of 0.619 and 0.264, respectively. Secondary woody vegetation at the Longoria WMA had a Simpson\u27s dominance value of 0.34 and the dominance of the secondary woody vegetation at the Anacua WMA was 0.66. Olive Sparrow densities at the Longoria and Anacua WMA\u27s were 2.5/ha and 0.5/ha, respectively. The greater secondary woody species diversity, smaller dominance, and higher density of Olive Sparrows found at the Longoria WMA were likely due to the greater age and density of the vegetation as well as the primary plant species introduced. A greater total vegetation volume and secondary woody species diversity appear to provide a more suitable habitat for the Olive Sparrow. It is likely that a greater diversity of avian species, including neotropical migrants, would be attracted to similar revegetated sites in this region, as such habitats mature
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