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Contribution of Ground-Based Cloud Observation to Satellite-Based Cloud Discrimination

Journal of Environmental Science and Engineering(A) 2013年第8期2卷 487-493页

作者： Mitsunori Yoshimura megumi yamashita Research and Development Center PASCO Corporation Meguro-ku153-0043 Tokyo Japan Institute of Agriculture Division of Environmental and Agricultural Engineering/Women's Future Developing Organization Tokyo University of Agriculture and Technology Fuchu183-8509 Tokyo Japan

One of the biggest factors to deteriorate the satellite product quality is cloud coverage. Therefore, cloud masking process is important to improve the quality of various satellite products. However, satellite-based cloud discrimination algorithm has been developing and efficient ground-based cloud observations are necessary to validate satellite-based cloud discrimination. The purpose of this study is to develop the efficient ground-based cloud observation methodology using whole sky camera. This paper deals with methods how to discriminate cloud portions on whole sky image, how to apply the ground-based cloud observation to the validations for satellite products. For the cloud discrimination on whole sky image, we propose SI （sky index） and BI （brightness index） calculated from RGB （red, green and blue） channels. SI shows the extent of the blueness and gray scale and BI indicates the extent of the brightness. Sun, cloud and blue sky portions are divided by SI and BI threshold. As an application of ground-based cloud observation for the validation of satellite products, clouds portions discriminated from whole sky image are projected onto ground surface with map coordinate. We also examine to compare with cloud portions on whole sky images and MODIS （MODerate resolution Imaging Spectroradiometer） image as one of experiments. The proposed ground-based cloud observation method and its extension to satellite-based cloud discrimination should be connected to improve the quality of satellite products.

关键词： Cloud discrimination whole sky camera S1 (sky index) BI (brightness index).

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Usefulness of noninvasive transient elastography for assessment of liver fibrosis stage in chronic hepatitis C

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World Journal of Gastroenterology 2006年第48期12卷 7768-7773页

作者： Tadashi Takeda Takahiro Yasuda Yuji Nakayama Mika Nakaya megumi Kimura Mariko yamashita Ayumi Sawada Koji Abo Setsuko Takeda Hiroki Sakaguchi Susumu Shiomi Hitoshi Asai Shuichi Seki Department of Hepatology Graduate School of Medicine Osaka City University Osaka Japan Central Clinical Laboratory Osaka City University Medical School Hospital Osaka Japan Department of Nuclear Medicine Graduate School of Medicine Osaka City University Osaka Japan Hitoshi Asai Health Service Center Osaka Kyoiku University Osaka Japan

AIM：To evaluate the method of noninvasive transient elastography for assessment of histological stage of liver fibrosis in patients with chronic hepatitis C （CHC）.METHODS： Two hundred and thirty-seven patients with CHC were included in this study. Liver biopsy was performed under ultrasonography on 217 of the patients, excluding twenty with clear clinical evidence of liver cirrhosis. Fifty subjects without liver disease were enrolled as a control group （stage 0）. Twentyfive patients with sustained virological response （SVR） to interferon （IFN） therapy were also enrolled. These patients underwent liver biopsy before IFN therapy. Examination of liver stiffness （LS） was performed by elastography.RESISTS： Medians （50% levels） of LS were 4.1 （3.5-4.9）, 6.3 （4.8-8.5）, 8.8 （6.8-12.0）, 14.6 （10.5-18.6）, and 22.2 （15.4-28.0）, respectively, in the fibrosis stages 0-4 （P 〈 0.001）. LS was significantly correlated with four serum fibrosis markers. LS values in patients with SVR were 3.8 （3.5-5.6）, 5.2 （4.4-6.8）, 6.8 （6.1-7.6）, and 6.1 （3.6-7.9）, respectively, in the fibrosis stages 1-4. In all stages, LS for patients with SVR was significantly lower than that for patients who did not undergo IFN therapy. LS was significantly correlated with serum concentrations of hyaluronic acid, type Ⅳ collagen, type Ⅳ collagen 7S, and type Ⅲ procollagen N peptide.CONCLUSION： LS correlated well with the histological stage of fibrosis. Changes in liver fibrosis stage may thus be estimated noninvasively using transient elastography.

关键词： Hepatitis C virus Echography Fibrosis Stiffness Interferon

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