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Design of a Switched Capacitor Negative Feedback Circuit for a Very Low Level DC Current Amplifier

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Circuits and Systems 2013年第4期4卷 356-363页

作者： hiroki higa Naoki Nakamura Faculty of Engineering University of the Ryukyus Okinawa Japan

To miniaturize a very low level dc current amplifier and to improve its output response speed, the switched capacitor negative feedback circuit (SCNF), instead of the conventionally used high-ohmage resistor, is presented in this paper. In our system, a switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier using SCNF. The theoretical output voltage of the very low level dc current amplifier using SCNF is obtained. The experimental results show that the unnecessary components of the amplifier’s output are much decreased, and that the response speed of the amplifier with both the SCNF and SCF is faster than that using high-ohmage resistor.

关键词： DC Amplifier Small Current Measurement Switched Capacitor

A Very Low Level dc Current Amplifier Using SC Circuit: Effects of Parasitic Capacitances and Duty Ratio on Its Output

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Open Journal of Applied Sciences 2014年第9期4卷 458-466页

作者： hiroki higa Ryota Onaga Naoki Nakamura Faculty of Engineering University of the Ryukyus Okinawa Japan

This paper describes a very low level dc current amplifier using switched capacitor (SC) circuit to miniaturize and improve its output response speed, instead of the conventionally used high-oh-mage resistor. A switched capacitor filter (SCF) and an offset controller are also used to decrease vibrations and offset voltage at the output of the amplifier. The simulation results show that the parasitic capacitances that are distributed to the input portion of the amplifier have some effect on offset voltage. From the experimental results, it is seen that the duty ratio of the clock cycle of SC circuit should be in the range from 0.05 to 0.70. It is suggested that the proposed very low level dc current amplifier using SC circuit is an effective way to obtain both a faster output response and its miniaturization.

关键词： dc Amplifier Small Current Measurement Switched Capacitor (SC) Circuit SC Filter

Direct visualization of postoperative aortobronchial fistula on computed tomography

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World Journal of Radiology 2024年第8期16卷 337-347页

作者： Nanae Tsuchiya Hitoshi Inafuku Satoko Yogi Yuko Iraha Gyo Iida Mizuki Ando Takaaki Nagano Shotaro higa Tatsuya Maeda Yuya Kise Kojiro Furukawa Koji Yonemoto Akihiro Nishie Department of Radiology Graduate School of Medical ScienceUniversity of the RyukyusOkinawa 903-0215Japan Department of Thoracic and Cardiovascular Surgery Graduate School of Medical ScienceUniversity of the RyukyusOkinawa 903-0215Japan Department of Biostatistics School of Health SciencesFaculty of MedicineUniversity of the RyukyusOkinawa 903-0215Japan

BACKGROUND Postoperative aortobronchial fistula(ABF)is a rare complication that can occur in 0.3%-5.0%of patients over an extended period of time after thoracic aortic *** visualization of the fistula via imaging is *** To investigate the relationship between computed tomography(CT)findings and the clinical signs/symptoms of ABF after thoracic aortic *** Six patients(mean age 71 years,including 4 men and 2 women)with suspected ABF on CT(air around the graft)at our hospital were included in this retrospective study between January 2004 and September *** CT findings included direct confirmation of ABF,peri-graft fluid,ring enhancement,dirty fat sign,atelectasis,pulmonary hemorrhage,and bronchodilation,and the clinical course were retrospectively *** proportion of each type of CT finding was *** ABF detection after surgery was found to have a mean and median of 14 and 13 years,*** signs and symptoms were asymptomatic in 4 patients,bloody sputum was found in 1 patient,and fever was present in 1 *** complications of ABF included graft infection in 2 patients and graft infection with hemoptysis in 2 *** the 6 patients,3 survived,2 died,and 1 was lost to *** locations of the ABFs were as follows:1 in the ascending aorta;1 in the aortic arch;2 in the aortic arch leading to the descending aorta;and 2 in the descending *** were directly confirmed by CT in 4/6(67%)***-graft dirty fat(4/6,67%)and peri-graft ring enhancement(3/6,50%)were associated with graft infection,endoleaks and pseudoaneurysms were associated with hemoptysis(2/6,33%).CONCLUSION Asymptomatic ABF after thoracic aortic surgery can be confirmed on chest *** is useful for the diagnosis of ABF and its complications.

关键词： Peri-graft air Aortobronchial fistula Chest computed tomography Postoperative Thoracic endovascular aortic repair Complication Thoracic aorta surgery

Clues to the signals for chloroplast photorelocation from the lifetimes of accumulation and avoidance responses

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Journal of Integrative Plant Biology 2015年第1期57卷 120-126页

作者： Takeshi higa Masamitsu Wada Department of Biology Faculty of Sciences Kyushu University

Chloroplast photo-relocation movement is crucial for plant survival; however, the mechanism of this phenome- non is still poorly understood. Especially, the signal that goes from photoreceptor to chloroplast is unknown, although the photoreceptors （phototropin 1 and 2） have been identified and an actin structure （chloroplast actin filaments） has been characterized that is specific for chloroplast movement. Here, in gametophytes of the fern Adiantum capillus-veneris, gametophores of the moss Physcomiterella patens, and leaves of the seed plant Arabidopsis thaliana, we sought to characterize the signaling system by measuring the lifetime of the induced response. Chloroplast movements were induced by microbeam irradiation with high-intensity blue light and recorded. The lifetime of the avoidance state was measured as a lag time between switching off the beam and the loss of avoidance behavior, and that of the accumulation state was measured as the duration of accumulation behavior following the extinction of the beam. The lifetime for the avoidance response state is approximately 3-4rain and that for the accumulation response is 19-28 rain. These data suggest that the two responses are based on distinct signals.

关键词： Blue light chloroplast movement fern gametophyte intracellular signaling phototropin

Unsteady Correlation between Pressure and Temperature Field on Impinging Plate for Dual Underexpanded Jets

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Journal of Thermal Science 2009年第3期18卷 215-219页

作者： Minoru YAGA Hiroyuki higa Shoichi MATSUDA Izuru SENAHA Depts. Mech. Systems Eng. Univ. of the Ryukyus Graduate student Faculty of Eng. Univ. of the Ryukyus Okinawa National College of Technology

In this paper, dual underexpanded impinging jets are experimentally studied by measuring unsteady wall staticpressure and temperature fields using high response semiconductor pressure sensors and infrared imaging cam-era(100 captures per sec) with dual converging sonic nozzles. The flow field is also visualized by means of highspeed schlieren system( up to 70000 frame per second) to clarify the unsteady behavior of the jet structures suchas barrel shock wave, and Mach disk. Experiments were performed with a blow down tunnel changing the parameterssuch as the nozzle to plate distance, the distance between the two nozzles, and wind tunnel pressure *** nozzle to plate distance L and the distance between the two nozzles H are non-dimensionalized by the nozzlediameter D covering H/D=1.5, 2.0, and 3, L/D= 2, 3,and 4, and po/pb=1.0 - 5.0, where po and pb are stagnationpressure and back pressure respectively. Although the response of the infrared camera is quite different fromthat of the high speed camera, the unsteady correlation between the pressure and temperature fields is confirmedunder some conditions. Also the high speed schlieren pictures and the wall static pressure fluctuations suggestthat the generation of the Mach disk promote the unsteady behavior of the jets. After the confirmation of the correlation,a simple way to find the severe fluctuating region can be provided according to the two dimensional unsteadytemperature images without a lot of unsteady pressure measurements.

关键词： Shock wave CFD supersonic flow unsteady jet fluctuation

Engineered three-dimensional rabbit oral epithelial–mesenchymal–muscular hybrid sheets

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International Journal of Oral Science 2016年第3期8卷 145-154页

作者： Shigeki Yamane Kazunari higa Takashi Umezawa Masamitsu Serikawa Jun Shimazaki Shinichi Abe Department of Anatomy Tokyo Dental College Tokyo Japan Department of Ophthalmology/Cornea Center Tokyo Dental College Chiba Japan

Regenerative muscles are required for swallowing and mastication, and are important for functional recovery from diseases involving oral muscular defects. Therefore, we generated three-layer hybrid sheets, similar to oral mucosal structures containing submucosal muscles, using rabbit oral mucosa epithelial, mesenchymal, and myoblastic progenitor cells, and examined the structural proteins. Each cell type was obtained from rabbit oral mucosa using enzymatic digestion. Isolated mesenchymal and myoblastic cells were multi-differentiated into osteoblasts, adipocytes, and chondrocytes or myotubes. Isolated epithelial cells were cultured on collagen gels containing isolated mesenchymal cells for 2 weeks, and these epithelial-mesenchymal cell sheets were laminated onto myoblastic cell sheets. The engineered hybrid sheets were multi-stratified in the epithelial and myoblastic layers in a time-dependent manner, expressing intermediate cytoskeletal filament proteins of epithelium and muscle. Hybrid sheets also expressed extracellular matrix basement membrane proteins. Immature cell markers for epithelial and myoblastic cells were observed continuously in hybrid sheet cultures. We established engineered three-dimensional rabbit oral mucosa hybrid sheets containing each immature cell type in vitro.

关键词： mesenchymal stem cell multi-differentiation myoblast oral mucosa three-dimensional culture

Autoimmune Hepatitis: Clinical Review with Insights into the Purinergic Mechanism of Disease

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Journal of Clinical and Translational Hepatology 2013年第2期1卷 79-86页

作者： Nikhil Kapila Jennifer T.higa Maria Serena Longhi Simon C.Robson Department of Medicine University of Connecticut Farmington CT USA Gastroenterology Division and Department of Medicine Beth Israel Deaconess Medical Center and Harvard Medical School Boston MA USA Gastroenterology Division and Department of Medicine Beth Israel Deaconess Medical Center and Harvard Medical School Boston MA USA Institute of Liver Studies King's College London School of Medicine at King's College Hospital Denmark Hill London UK

Autoimmune hepatitis (AIH) is an important disorder that predominantly results in inflammatory liver disease in genetically predisposed *** clinicopathological picture is characterized by symptoms associated with both systemic inflammation and hepatic dysfunction,and with increased serum aminotransferases,elevated IgG,autoantibodies,and interface hepatitis on liver *** usually results in liver injury as a consequence of chronic hepatitis and ***,rarely,patients may present with fulminant liver *** diagnosis is important in all instances because the disease can be highly responsive to immunosuppressive therapeutic *** untreated,the disease is associated with high morbidity and *** we provide an overview of the current state of knowledge on AIH and summarize the treatment options for this serious condition in *** also discuss the pathogenesis of the disease as a possible consequence of autoimmunity and the breakdown of hepatic *** focus on regulatory T cell impairments as a consequence of changes in CD39 ectonucleotidase expression and altered purinergic *** understanding of hepatic tolerance may aid in the development of specific and well-tolerated therapies for AIH.

关键词： Autoimmune hepatitis Pathogenesis Immunology Purinergic CD39 Therapeutic overview

Effects of climate change on potential habitats of the cold temperate coniferous forest in Yunnan province, southwestern China

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Journal of Mountain Science 2016年第8期13卷 1411-1422页

作者： LIWang-jun PENG Ming-chun Motoki higa Nobuyuki TANAKA Tetsuya MATSUI Cindy Q. TANG OU Xiao-kun ZHOU Rui-wu WANG Chong-yun YAN Hai-zhong Institute of Ecology and Geobotany Yunnan University Kunming 650091 China Kochi University Kochi-shi Kochi 780-8520 Japan Forestry and Forest Products Research Institute 1 Matsunosato Tsukuba Ibaraki 305-8687 Japan Tokyo University of Agriculture 1-1-1 Sakuragaoka Setagaya-ku Tokyo 156-8502 Japan

We built a classification tree （CT） model to estimate climatic factors controlling the cold temperate coniferous forest （CTCF） distributions in Yunnan province and to predict its potential habitats under the current and future climates, using seven climate change scenarios, projected over the years of 2070-2099. The accurate CT model on CTCFs showed that minimum temperature of coldest month （TMW） was the overwhelmingly potent factor among the six climate variables. The areas of TMW〈-4.05 were suitable habitats of CTCF, and the areas of -1.35 〈 TMW were non-habitats, where temperate conifer and broad-leaved mixed forests （TCBLFs） were distribute in lower elevation, bordering on the CTCF. Dominant species of Abies, Picea, and Larix in the CTCFs, are more tolerant to winter coldness than Tsuga and broad-leaved trees including deciduous broad-leaved Acer and Betula, evergreen broad- leaved Cyclobalanopsis and Lithocarpus in TCBLFs. Winter coldness may actually limit the cool-side distributions of TCBLFs in the areas between -1.35℃ and -4.05℃, and the warm-side distributions of CTCFs may be controlled by competition to the species of TCBLFs. Under future climate scenarios, the vulnerable area, where current potential （suitable ＋ marginal） habitats （80,749 km^2） shift to non-habitats, was predicted to decrease to 55.91% （45,053 km^2） of the current area. Inferring from the current vegetation distribution pattern, TCBLFs will replace declining CTCFs. Vulnerable areas predicted by models are important in determining priority of ecosystem conservation.

关键词： Classification tree Climate scenarios Vulnerable area Abies Picea Larix Evergreenbroad-leaved tree ALOS remote-sensing images

Current status and future perspectives of radiomics in hepatocellular carcinoma

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World Journal of Gastroenterology 2023年第1期29卷 43-60页

作者： Joao Miranda Natally Horvat Gilton Marques Fonseca Jose de Arimateia Batista Araujo-Filho Maria ClaraFernandes Charlotte Charbel Jayasree Chakraborty Fabricio Ferreira Coelho Cesar higa Nomura Paulo Herman Department of Radiology University of Sao PauloSao Paulo 05403-010Brazil Department of Radiology Memorial Sloan-Kettering Cancer CenterNew YorkNY 10065United States Department of Gastroenterology University of Sao PauloSao Paulo 05403-000Brazil Department of Radiology Hospital Sirio-LibanesSao Paulo 01308-050Brazil Department of Surgery Memorial Sloan-Kettering Cancer CenterNew YorkNY 10065United States Department of Radiology University of Sao PauloSao Paulo 05403-000Brazil

Given the frequent co-existence of an aggressive tumor and underlying chronic liver disease,the management of hepatocellular carcinoma(HCC)patients requires experienced multidisciplinary team ***,imaging plays a key role in the diagnosis,staging,restaging,and surveillance of ***,imaging assessment of HCC entails the assessment of qualitative characteristics which are prone to inter-reader *** is an emerging field that extracts high-dimensional mineable quantitative features that cannot be assessed visually with the naked eye from medical *** main potential applications of radiomic models in HCC are to predict histology,response to treatment,genetic signature,recurrence,and *** the encouraging results to date,there are challenges and limitations that need to be overcome before radiomics implementation in clinical *** purpose of this article is to review the main concepts and challenges pertaining to radiomics,and to review recent studies and potential applications of radiomics in HCC.

关键词： Radiomics Hepatocellular carcinoma Texture analysis Radiology