934 resultados para spontaneously generated coherence


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The purpose of this study was to compare inter-observer agreement of Stratus™ OCT versus Spectralis™ OCT image grading in patients with neovascular age-related macular degeneration (AMD). Thirty eyes with neovascular AMD were examined with Stratus™ OCT and Spectralis™ OCT. Four different scan protocols were used for imaging. Three observers graded the images for the presence of various pathologies. Inter-observer agreement between OCT models was assessed by calculating intra-class correlation coefficients (ICC). In Stratus™ OCT highest interobserver agreement was found for subretinal fluid (ICC: 0.79), and in Spectralis™ OCT for intraretinal cysts (IRC) (ICC: 0.93). Spectralis™ OCT showed superior interobserver agreement for IRC and epiretinal membranes (ERM) (ICC(Stratus™): for IRC 0.61; for ERM 0.56; ICC(Spectralis™): for IRC 0.93; for ERM 0.84). Increased image resolution of Spectralis™ OCT did improve the inter-observer agreement for grading intraretinal cysts and epiretinal membranes but not for other retinal changes.

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This study sought to assess stent strut coverage, malapposition, protrusion, and coronary evaginations as markers of healing 5 years after implantation of sirolimus-eluting stents (SES) and paclitaxel-eluting stents (PES), by optical coherence tomography (OCT).

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To demonstrate the feasibility and potential usefulness of an offline fusion of matched optical coherence tomography (OCT) and intravascular ultrasound (IVUS)/virtual histology (IVUS-VH) images.

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The purpose of this document is to make the output of the International Working Group for Intravascular Optical Coherence Tomography (IWG-IVOCT) Standardization and Validation available to medical and scientific communities, through a peer-reviewed publication, in the interest of improving the diagnosis and treatment of patients with atherosclerosis, including coronary artery disease.

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To quantify the circumferential healing process at 6 and 12 months following scaffold implantation.

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To analyse and to compare the changes in the various optical coherence tomography (OCT), echogenicity and intravascular ultrasound virtual histology (VH) of the everolimus-eluting bioresorbable scaffold (ABSORB) degradation parameters during the first 12 months after ABSORB implantation. In the ABSORB study, changes in the appearance of the ABSORB scaffold were monitored over time using various intracoronary imaging modalities. The scaffold struts exhibited a progressive change in their black core area by OCT, in their ultrasound derived grey level intensity quantified by echogenicity, and in their backscattering ultrasound signal, identified as "pseudo dense-calcium" (DC) by VH.

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The separation of small molecules by capillary electrophoresis is governed by a complex interplay among several physical effects. Until recently, a systematic understanding of how the influence of all of these effects is observed experimentally has remained unclear. The work presented in this thesis involves the use of transient isotachophoretic stacking (tITP) and computer simulation to improve and better understand an in-capillary chemical assay for creatinine. This assay involves the use of electrophoretically mediated micro-analysis (EMMA) to carry out the Jaffé reaction inside a capillary tube. The primary contribution of this work is the elucidation of the role of the length and concentration of the hydroxide plug used to achieve tITP stacking of the product formed by the in-capillary EMMA/Jaffé method. Computer simulation using SIMUL 5.0 predicts that a 3-4 fold gain in sensitivity can be recognized by timing the tITP stacking event such that the Jaffé product peak is at its maximum height as that peak is electrophoresing past the detection window. Overall, the length of the hydroxide plug alters the timing of the stacking event and lower concentration plugs of hydroxide lead to more rapidly occurring tITP stacking events. Also, the inclusion of intentional tITP stacking in the EMMA/Jaffé method improves the sensitivity of the assay, including creatinine concentrations within the normal biological range. Ultimately, improvement in assay sensitivity can be rationally designed by using the length and concentration of the hydroxide plug to engineer the timing of the tITP stacking event such that stacking occurs as the Jaffé product is passing the detection window.

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Given the weight sequence for a subnormal recursively generated weighted shift on Hilbert space, one approach to the study of classes of operators weaker than subnormal has been to form a backward extension of the shift by prefixing weights to the sequence. We characterize positive quadratic hyponormality and revisit quadratic hyponormality of certain such backward extensions of arbitrary length, generalizing earlier results, and also show that a function apparently introduced as a matter of convenience for quadratic hyponormality actually captures considerable information about positive quadratic hyponormality.