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Investigation of changes in thickness and reflectivity from layered retinal structures of healthy and diabetic eyes with optical coherence tomography

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Journal of Biomedical Science and Engineering 2011年第10期4卷 657-665页

作者： Wei Gao Erika Tatrai Veronika Olvedy boglarka varga Lenke Laurik Aniko Somogyi Gabor Mark Somfai Delia Cabrera DeBuc Bascom Palmer Eye Institute University of Miami Miller School of MedicineMiamiUSA Semmelweis University Department of OphthalmologyBudapestHungary Semmelweis University 2^(nd) Department of Internal MedicineBudapestHungary

OCT is usually employed for the measurement of retinal thickness. However, coherent reflected light carries more information characterizing the optical properties of tissue. Therefore, optical property changes may provide further information regarding cellular layers and early damage in ocular diseases. We investigated the possibility of OCT in detecting changes in the optical backscattered signal from layered retinal structures. OCT images were obtained from diabetic patients without retinopathy (DM, n = 38 eyes) or mild diabetic retinopathy (MDR, n = 43 eyes) and normal healthy subjects (n = 74 eyes). The thickness and reflectivity of various layered structures were assessed using a custom-built algorithm. In addition, we evaluated the usefulness of quantifying the reflectivity of layered structures in the detection of retinal damage. Generalized estimating equations considering within-subject inter-eye relations were used to test for differences between the groups. A modified p value of <0.001 was considered statistically significant. Receiver operating characteristic (ROC) curves were constructed to describe the ability of each parameter to discriminate between the eyes of DM, MDR and healthy eyes. Thickness values of the GCL + IPL and OPL showed a significant decrease in the MDR eyes compared to controls. Significant decreases of total reflectance average values were observed in all layers in the MDR eyes compared with controls. The highest AUROC values estimated for the total reflectance were observed for the GCL+IPL, OPL and OS when comparing MDR eyes with controls. Total reflectance showed a better discriminating power between the MDR eyes and healthy eyes compared to thickness values. Our results suggest that the optical properties of the intraretinal layers may provide useful information to differentiate pathological from healthy eyes. Further research is warranted to determine how this approach may be used to improve diagnosis of early retinal neurodegene

关键词： Optical Coherence Tomography Rerina Diabetic Retinopathy Segmentation Image Processing

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Redistribution of Soil Organic Carbon Triggered by Erosion at Field Scale Under Subhumid Climate,Hungary

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Pedosphere 2016年第5期26卷 652-665页

作者： Zoltan SZALAI Judit SZABO Jozsef KOVACS Erzsebet MESZAROS Gaspar ALBERT Csaba CENTERI boglarka SZABO Balazs MADARASZ Dora ZACHARY Gergely JAKAB Geographical Institute Research Centre for Astronomy and Earth Sciences Hungarian Academy of SciencesBudapest 1112(Hungary) Department of Environmental and Landscape Geography Eotvos Lordnd UniversityBudapest 1117(Hungary) Department of Applied and Environmental Geology Eotvos Lordnd UniversityBudapest 1117(Hungary) Department of Cartography and Geoinformatics Eotvos Lordnd UniversityBudapest 1117(Hungary) Department of Nature Conservation and Landscape Ecology Szent Istvdn UniversityGodollo 2100(Hungary)

Soil organic carbon(SOC) has primary importance in terms of soil physics, soil fertility and even of climate change control. One hundred soil samples were taken from an intensively cultivated Cambisol to quantify SOC redistribution triggered by soil erosion under a subhumid climate, by the simultaneous application of diffuse reflectance(240–1 900 nm) and traditional physico-chemical *** representative sample points were collected from the solum along the slopes at the depth of 20–300 cm with a mean SOC content of 12 g kg^(-1). Hierarchical cluster analyses were performed based on the determined SOC results. The spatial pattern of the groups created were similar, and even though the classifications were not the same, diffuse reflectance had proven to be a suitable method for soil/sediment classification even within a given arable field. Both organic and inorganic carbon distributions were found to be a proper tool for estimations of past soil erosion processes. The SOC enrichment was found on two sedimentary spots with different geomorphological positions. Soil organic matter composition also differed between the two spots due to selective deposition of the delivered organic matter. The components with low-molecular-weight reached the bottom of the slope where they could leach into the profile, while the more polymerised organic matter compositions were delivered and deposited even before on a higher segment of the slope in an aggregated form. This spatial difference appeared below the uppermost tilled soil layer as well, referring the lower efficiency of conventional ploughing tillage in soil spatial homogenisation.

关键词： Cambisol carbon sequestration diffuse reflectance selective erosion soil organic matter composition

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