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Astrodynamics 2024年第1期8卷 47-60页

作者： yuki kubo Toshihiro Chujo Institute of Space and Astronautical Science Japan Aerospace Exploration AgencyKanagawa252-5210Japan Department of Mechanical Engineering Tokyo Institute of TechnologyTokyo152-8550Japan

The solar sail is one of the most promising space exploration systems due to its theoretically infinite specific impulse achieved through solar radiation pressure(SRP).Recently,researchers have proposed“transformable spacecraft”capable of actively reconfiguring their body configurations using actuatable joints.Transformable spacecraft,if used similarly to solar sails,are expected to significantly enhance orbit and attitude control capabilities owing to their high redundancy in control degrees of freedom.However,controlling them becomes challenging due to their large number of inputs,leading previous researchers to impose strong constraints to limit their potential control capabilities.This study focuses on novel attitude control techniques for transformable spacecraft under SRP.We developed two methods,namely,joint angle optimization to obtain arbitrary SRP force and torque,and momentum damping control driven by joint angle actuation.Our proposed methods are formulated in a general manner and can be applied to any transformable spacecraft comprising front faces that can predominantly receive the SRP on each body.The validity of our proposed method is confirmed through numerical simulations.Our study contributes to making most of the high control redundancy of transformable spacecraft without the need for expendable propellants,thus significantly enhancing the orbit and attitude control capabilities.

关键词： solar sail transformable spacecraft attitude-joint coupled motion attitudestabilization

Solar power sail mission of OKEANOS

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Astrodynamics 2020年第3期4卷 233-248页

作者： Osamu Mori Jun Matsumoto Toshihiro Chujo Masanori Matsushita Hideki Kato Takanao Saiki Yuichi Tsuda Jun'ichiro Kawaguchi Fuyuto Terui Yuya Mimasu Go Ono Naoko Ogawa yuki Takao yuki kubo Kaoru Ohashi Ahmed Kiyoshi Sugihara Tatsuaki Okada Takahiro Iwata Hajime Yano Japan Aerospace Exploration Agency Sagarmihara 252-5210Japan Tokyo Institute of Technology Tokyo 152-8550Japan The University of Tokyo Tokyo 113-8654Japan Patchedconics LLCSagarmihara 252-5210Japan

The solar power sail is an original Japanese concept in which electric power is generated by thin-film solar cells attached on the solar sail membrane.Japan Aerospace Exploration Agency(JAXA)successfully demonstrated the world’s first solar power sail technology through IKAROS(Interplanetary Kite-craft Accelerated by Radiation of the Sun)mission in 2010.IKAROS demonstrated photon propulsion and power generation using thin-film solar cells during its interplanetary cruise.Scaled up,solar power sails can generate enough power to drive high specific impulse ion thrusters in the outer planetary region.With this concept,we propose a landing or sample return mission to directly explore a Jupiter Trojan asteroid using solar power sail-craft OKEANOS(Oversize Kite-craft for Exploration and AstroNautics in the Outer Solar System).After rendezvousing with a Trojan asteroid,a lander separates from OKEANOS to collect samples,and perform in-situ analyses in three proposed mission sequences,including sending samples back to Earth.This paper proposes a system design for OKEANOS and includes analyses of the latest mission.

关键词： solar power sail Trojan asteroid landing in-situ analysis outer solar system OKEANOS

A unique case of collagenous colitis presenting as protein-losing enteropathy successfully treated with prednisolone

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World Journal of Gastroenterology 2008年第39期14卷 6083-6086页

作者： Soichi Sano Keiko Yamagami Ayako Tanaka Minako Nishio Tomoyuki Nakamura yuki kubo Takeshi Inoue Wataru Ueda Kiyotaka Okawa Katsunobu Yoshioka Department of Internal Medicine Osaka City General HospitalOsaka 534-0021Japan Department of Pathology Osaka City General HospitalOsaka 534-0021Japan Department of Gastroen-terology Osaka City General HospitalOsaka 534-0021Japan

A 76-year-old woman with a 5-mo history of recurrent diarrhea and generalized edema was admitted to our hospital. Colonoscopy revealed edematous mucosa,and histopathological examination was compatible with collagenous colitis. Protein leakage from the colon,particularly in the ascending portion,was identified on 99mTc-human serum albumin scintigraphy. Collagenous colitis associated with protein-losing enteropathy (PLE) without small bowel disease was diagnosed. Prednisolone treatment ameliorated diarrhea and hypoproteinemia. Collagenous colitis should be included in the differential diagnosis of chronic diarrhea with hypoproteinemia for appropriate management.

关键词：胶原大肠炎蛋白质肠病血清检查

Acquiring non-parametric scattering phase function from a single image

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Computational Visual Media 2018年第4期4卷 323-331页

作者： yuki Minetomo Hiroyuki kubo Takuya Funatomi Mikio Shinya Yasuhiro Mukaigawa Nara Institute of Science and Technology 8916-5 Takayama-choIkomaNara630-0192Japan. Toho University 2-2-1 MiyamaFunabashiChiba274- 8510Japan. Dwango CG Research KADOKAWA Hongo Bldg.5-24-5 HongoBunkyo-kuTokyo113-0033Japan.

Acquiring accurate scattering properties is important for rendering translucent materials. In particular, the phase function, which determines the distribution of scattering directions, plays a significant role in the appearance of a material. We propose a distinctive scattering theory that approximates the effect of single scattering to acquire the non-parametric phase function from a single image. Furthermore, in various experiments, we measured the phase functions from several real diluted media and rendered images of these materials to evaluate the effectiveness of our theory.

关键词： scattering phase function measurement rendering

Plasma copeptin concentration is a predictor of tolvaptan efficacy in patients with hepatic ascites

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Portal Hypertension & Cirrhosis 2023年第3期2卷 109-114页

作者： Fumimasa Tomooka Kei Moriya Takahiro kubo Akihiko Shibamoto Jyunya Suzuki Satoshi Iwai Soichi Takeda yuki Fujimoto Masahide Enomoto Koji Murata yuki Tsuji yukihisa Fujinaga Koh Kitagawa Norihisa Nishimura Hiroaki Takaya Kosuke Kaji Hideto Kawaratani Tadashi Namisaki Takemi Akahane Akira Mitoro Hitoshi Yoshiji Department of Gastroenterology and Hepatology Nara Medical UniversityKashiharaJapan Department of Gastroenterology Nara Prefectural General Medical CenterShichijo-NishimachiJapan

Aims:No solid evidence-based opinion was raised regarding predictors of the degree of ascites reduction with tolvaptan.This retrospective cohort study aimed to examine whether serum copeptin concentration is a useful predictor of this.Methods:The study population consisted of 80 patients with liver cirrhosis treated with tolvaptan for hepatic ascites effusions at Nara Medical University Hospital from May 2014 to December 2018.Forty-three patients who lost>1.5 kg of body weight in the first week after starting tolvaptan were classified as good responders and the remaining 37 as poor responders.Various laboratory parameters were measured immediately before the start of tolvaptan therapy to examine factors associated with predicting its efficacy.Results:In the univariate analysis,no significant differences with respect to age(67.6 vs.69.8 years,p>0.05),sex,body mass index(24.8 vs.23.7 kg/m^(2),p>0.05),Child-Pugh score(9.4 vs.9.7,p>0.05),and Model for End-stage Liver Disease score(11 vs.12,p>0.05)were found between the two groups.Conversely,aspartate transferase and alanine transaminase(ALT)levels were significantly lower in the good response group(52.9±56.3 vs.68.8±50.7 U/L,p<0.05;26.2±30.6 vs.40.5±33.5 U/L,p<0.01),whereas serum copeptin and serum sodium concentrations were significantly higher(57.1±15.0 vs.45.8±16.0 pg/mL,p<0.01;136.3±3.4 vs.133.8±5.8 mEq/L,p<0.05).In the multivariate analysis,serum copeptin concentration and ALT were statistically significant factors(p<0.01,p<0.05).Regression analysis of the association between the tolvaptan efficacy for refractory ascites and pretreatment serum copeptin concentration showed that a copeptin concentration cutoff of 45.9 pg/mL could predict treatment efficacy with a sensitivity,specificity,and area under the curve of 76.7%,59.5%,and 0.71%,respectively.Conclusion:Serum copeptin concentration may be a predictor of tolvaptan efficacy for refractory ascites effusion in Japanese patients with liver cirrhosis.

关键词： ascites copeptin decompensated liver cirrhosis diuretics tolvaptan

Relationships of youth risk behaviors with norm-consciousness and resilience among Japanese high school students

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Open Journal of Preventive Medicine 2012年第3期2卷 306-311页

作者： Chie Kataoka Yuji Nozu Shiori Kawahara Hiroko Kuroiwa Masako Kudo yuki Sato Motoyoshi kubo Motoi Watanabe Faculty of Education Utsunomiya University Graduate School of Comprehensive Human Sciences University of Tsukuba Hokkaido University of Education Tomiya Junior High School

The purpose of this study was to examine the influences of norm-consciousness and resilience on the prevention of youth risk behaviors among Japanese high school students. Data of a national survey, Japan Youth Risk Behavior Survey 2011, was used for this analysis. The subjects were 9778 students (5027 males, 4751 females) in grades 10-12 in 102 schools randomly selected from among high schools throughout Japan. When multiple regression analysis was carried out using four subdomains of norm-consciousness and three subdomains of resilience as the independent variables and nine risk behaviors as the dependent variables, the subdomains of norm-consciousness showed significant positive standardized partial regression coefficients for eight risk behaviors for both males and females. In particular, “current alcohol use” and “ever had sexual intercourse” showed the largest standardized partial regression coefficients for the norm-consciousness in school, and “current cigarette use” showed that for the norm-consciousness in community. The subdomains of resilience showed significant positive standardized partial regression coefficients for five risk behaviors for males and for six those for females. The results of this study suggest that the norm-consciousness is an important protective factor to comprehensively prevent risk behaviors among Japanese adolescents. It is expected to be effective to enhance the norm-consciousness particularly in school and community. In addition, resilience should also be emphasized as a factor to prevent specific risk behaviors.

关键词： Youth Risk Behavior Norm-Consciousness Resilience Japan

Correlation between Non-Alcoholic Beverage Consumption and Alcohol Drinking Behavior among Japanese Youths

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Open Journal of Preventive Medicine 2015年第2期5卷 31-37页

作者： Motoyoshi kubo Yuji Nozu Chie Kataoka Masako Kudo Shiori Taniguchi yuki Sato Naoko Nakayama Motoi Watanabe Faculty of Education Utsunomiya University Utsunomiya Japan Faculty of Health and Sport Sciences University of Tsukuba Tsukuba Japan Graduate School of Comprehensive Human Sciences University of Tsukuba Tsukuba Japan Narita Junior High School Tomiya Japan St. Luke’s International University Tokyo Japan Hokkaido University of Education Sapporo Japan

The purpose of this study was to investigate the correlation between the consumption of non-alcoholic beverages (such as non-alcoholic beer, non-alcoholic cocktails, and non-alcoholic wine) and alcohol drinking behavior among Japanese youths. Data from the Japan Youth Risk Behavior Survey 2011 were analyzed. The study subjects were 9775 high school students (5026 males and 4749 females) randomly selected from the 10th to the 12th grade in 102 high schools throughout Japan. The results indicated that the percentage of youths who had consumed non-alcoholic beverages was 25.8% among males (11.5%: “one time”;14.3%: “two or more times”) and 26.1% among females (12.2%: “one time”;13.9%: “two or more times”), which suggested that at least one in four Japanese high school students had consumed non-alcoholic beverages. Those students that had consumed non-alcoholic beverages were at a significantly higher risk for alcohol-related behaviors, including “ever drank alcohol”, “current alcohol use”, “current frequent alcohol use”, and “chugging”, when compared with students who had never consumed non-alcoholic beverages. The risk for alcohol-related behaviors was higher for students who had consumed non-alcoholic beverages two or more times than for those who had consumed them one time. Specifically, the odds ratio for “ever drank alcohol” in the “one time” group was 5.16 (95% CI: 4.22 - 6.30) for males and 4.27 (95% CI: 3.53 - 5.16) for females, while it was markedly high for those in the “two or more times” group, with males at 9.78 (95% CI: 7.88 - 12.14) and females at 7.59 (95% CI: 6.20 - 9.29). The results of this study suggest that it is necessary to continuously ascertain the prevalence of non-alcoholic beverage consumption among Japanese youths. In addition, alcohol drinking prevention in youths requires attention be paid not only to their consumption of alcoholic beverages, but also to their consumption of non-alcoholic beverages.

关键词： Youth Non-Alcoholic Beverage Alcohol Drinking National Survey

SERIOUS DAMAGES OF ASR AFFECTED RC BRIDGE PIERS AND THEIR STRENGTHENING TECHNIQUES

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SERIOUS DAMAGES OF ASR AFFECTED RC BRIDGE PIERS AND THEIR ST...