233 research outputs found

    Toward time resolved 4D cardiac CT imaging with patient dose reduction: estimating the global heart motion

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    Development of a computer-generated model for the coronary arterial tree based on multislice CT and morphometric data

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    Effect of heart rate on CT angiography using the enhanced cardiac model of the 4D NCAT

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    Quenching and reactivation of electroluminescence by charge trapping and detrapping in Si-implanted silicon nitride thin film

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    In this brief, quenching of electroluminescence (EL) from Si-implanted silicon nitride (SNR) thin film under a forward bias has been observed. The quenching phenomenon is shown to be due to charge trapping in the defect states involved in the radiative recombination. The composite EL bands have different quenching rates, causing a change in the EL spectrum shape by the EL quenching. Release of the trapped charges by a low-temperature annealing at 120 Β°C or an application of a reverse gate bias can partially recover the quenched EL both in the intensity and spectrum shape. The quenching phenomenon poses a serious challenge to the application of Si-implanted SNR thin films in light-emitting devices. Β© 2009 IEEE.published_or_final_versio

    Evolution of electroluminescence from multiple Si-implanted silicon nitride films with thermal annealing

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    Influence of thermal annealing on electroluminescence (EL) from multiple-Si-implanted silicon nitride films has been investigated. A reduced injection current and an enhanced EL intensity have been obtained simultaneously by increasing the annealing temperature, which results in a higher EL quantum efficiency. In addition, four emission bands are identified, and their peak energies, intensities, and full widths at half maxima are found to change with annealing temperature. A model is proposed to illustrate the carrier transport, the mechanisms of the four emission bands, and the evolution of the EL bands with annealing as well. The two major bands and the minor ultraviolet band are explained in terms of the recombination of the injected electrons in either the silicon dangling-bond (≑ Si 0) states or the nitride conduction band with the injected holes in either the band tail states above the nitride valence band or the valence band itself, while the minor near infrared band is attributed to the Si nanocrystals formed in the thin film. Β© 2009 American Institute of Physics.published_or_final_versio

    Primary Phacoemulsification and Intraocular Lens Implantation for Acute Primary Angle-Closure

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    Background: To investigate the effect of primary phacoemulsification on intraocular pressure (IOP) in patients with acute primary angle-closure (PAC) and coexisting cataract. Methodology: Sixteen eyes of 14 patients with acute PAC received phacoemulsification and intraocular lens implantation as initial management for medically uncontrolled IOP in a retrospective chart review. The effects on IOP, vision, anterior chamber depth (ACD), and number of antiglaucoma medications were evaluated. Principal Findings: The postoperative IOP was reduced in 16 eyes (100%). The mean 6 standard deviation preoperative IOP was 48.81616.83 mm Hg, which decreased postoperatively to 16.46610.67 mm Hg at 1 day, 9.4363.03 mm Hg at 1 week

    Liver Enzymes: Interaction Analysis of Smoking with Alcohol Consumption or BMI, Comparing AST and ALT to Ξ³-GT

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    A detrimental interaction between smoking and alcohol consumption with respect serum Ξ³-glutamyltransferase (Ξ³-GT) has recently been described. The underlying mechanisms remain unknown. The present work aimed to provide further insights by examining similar interactions pertaining to aspartate and alanine transaminase (AST, ALT), routine liver markers less prone to enzyme induction.<0.0001). The interactions all were in the same directions as for Ξ³-GT, i.e. synergistic with alcohol and opposite with BMI.The patterns of interaction between smoking and alcohol consumption or BMI with respect to AST and ALT resembled those observed for Ξ³-GT. This renders enzyme induction a less probable mechanism for these associations, whereas it might implicate exacerbated hepatocellular vulnerability and injury

    Regularized gene selection in cancer microarray meta-analysis

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    <p>Abstract</p> <p>Background</p> <p>In cancer studies, it is common that multiple microarray experiments are conducted to measure the same clinical outcome and expressions of the same set of genes. An important goal of such experiments is to identify a subset of genes that can potentially serve as predictive markers for cancer development and progression. Analyses of individual experiments may lead to unreliable gene selection results because of the small sample sizes. Meta analysis can be used to pool multiple experiments, increase statistical power, and achieve more reliable gene selection. The meta analysis of cancer microarray data is challenging because of the high dimensionality of gene expressions and the differences in experimental settings amongst different experiments.</p> <p>Results</p> <p>We propose a Meta Threshold Gradient Descent Regularization (MTGDR) approach for gene selection in the meta analysis of cancer microarray data. The MTGDR has many advantages over existing approaches. It allows different experiments to have different experimental settings. It can account for the joint effects of multiple genes on cancer, and it can select the same set of cancer-associated genes across multiple experiments. Simulation studies and analyses of multiple pancreatic and liver cancer experiments demonstrate the superior performance of the MTGDR.</p> <p>Conclusion</p> <p>The MTGDR provides an effective way of analyzing multiple cancer microarray studies and selecting reliable cancer-associated genes.</p
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