K
Ko Okumura
Researcher at Juntendo University
Publications - 1123
Citations - 71408
Ko Okumura is an academic researcher from Juntendo University. The author has contributed to research in topics: T cell & Antigen. The author has an hindex of 134, co-authored 1057 publications receiving 67530 citations. Previous affiliations of Ko Okumura include Tokai University & Nagoya City University.
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Journal ArticleDOI
Evidence for oscillation of atmospheric neutrinos
Y. Fukuda,T. Hayakawa,E. Ichihara,Kunio Inoue,K. Ishihara,H. Ishino,Yoshitaka Itow,Takaaki Kajita,J. Kameda,S. Kasuga,Ken-ichiro Kobayashi,Yohei Kobayashi,Yusuke Koshio,M. Miura,Masayuki Nakahata,S. Nakayama,A. Okada,Ko Okumura,N. Sakurai,Masato Shiozawa,Yoshihiro Suzuki,Y. Takeuchi,Y. Totsuka,Shinya Yamada,M. Earl,Alec Habig,E. Kearns,M. D. Messier,Kate Scholberg,J. L. Stone,Lawrence Sulak,C. W. Walter,M. Goldhaber,T. Barszczxak,D. Casper,W. Gajewski,P. G. Halverson,J. Hsu,W. R. Kropp,L. R. Price,Frederick Reines,Michael B. Smy,Henry W. Sobel,Mark R. Vagins,K. S. Ganezer,W. E. Keig,R. W. Ellsworth,S. Tasaka,J. W. Flanagan,A. Kibayashi,John G. Learned,S. Matsuno,V. J. Stenger,D. Takemori,T. Ishii,Junichi Kanzaki,T. Kobayashi,S. Mine,K. Nakamura,K. Nishikawa,Yuichi Oyama,A. Sakai,Makoto Sakuda,Osamu Sasaki,S. Echigo,M. Kohama,A. T. Suzuki,Todd Haines,Todd Haines,E. Blaufuss,B. K. Kim,R. Sanford,R. Svoboda,M. L. Chen,Z. Conner,Z. Conner,J. A. Goodman,G. W. Sullivan,J. Hill,C. K. Jung,K. Martens,C. Mauger,C. McGrew,E. Sharkey,B. Viren,C. Yanagisawa,W. Doki,Kazumasa Miyano,H. Okazawa,C. Saji,M. Takahata,Y. Nagashima,M. Takita,Takashi Yamaguchi,Minoru Yoshida,Soo-Bong Kim,M. Etoh,K. Fujita,Akira Hasegawa,Takehisa Hasegawa,S. Hatakeyama,T. Iwamoto,M. Koga,Tomoyuki Maruyama,Hiroshi Ogawa,J. Shirai,A. Suzuki,F. Tsushima,Masatoshi Koshiba,M. Nemoto,Kyoshi Nishijima,T. Futagami,Y. Hayato,Y. Kanaya,K. Kaneyuki,Y. Watanabe,D. Kielczewska,D. Kielczewska,R. A. Doyle,J. S. George,A. L. Stachyra,L. Wai,L. Wai,R. J. Wilkes,K. K. Young +124 more
Abstract: We present an analysis of atmospheric neutrino data from a 33.0 kton yr (535-day) exposure of the Super-Kamiokande detector. The data exhibit a zenith angle dependent deficit of muon neutrinos which is inconsistent with expectations based on calculations of the atmospheric neutrino flux. Experimental biases and uncertainties in the prediction of neutrino fluxes and cross sections are unable to explain our observation. The data are consistent, however, with two-flavor ${\ensuremath{
u}}_{\ensuremath{\mu}}\ensuremath{\leftrightarrow}{\ensuremath{
u}}_{\ensuremath{\tau}}$ oscillations with ${sin}^{2}2\ensuremath{\theta}g0.82$ and $5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}l\ensuremath{\Delta}{m}^{2}l6\ifmmode\times\else\texttimes\fi{}1{0}^{\ensuremath{-}3}\mathrm{eV}{}^{2}$ at 90% confidence level.
Journal ArticleDOI
Expression of Programmed Death 1 Ligands by Murine T Cells and APC
Tomohide Yamazaki,Hisaya Akiba,Hideyuki Iwai,Hironori Matsuda,Mami Aoki,Yuka Tanno,Tahiro Shin,Haruo Tsuchiya,Drew M. Pardoll,Ko Okumura,Miyuki Azuma,Hideo Yagita +11 more
TL;DR: B7-H1 was broadly expressed on the surface of mouse tumor cell lines while the expression of B7-DC was rather restricted, and the inducible expression of PD-1 ligands on both T cells and APCs may suggest new paradigms ofPD-1-mediated immune regulation.
Journal ArticleDOI
Involvement of tumor necrosis factor-related apoptosis-inducing ligand in surveillance of tumor metastasis by liver natural killer cells.
Kazuyoshi Takeda,Yoshihiro Hayakawa,Mark J. Smyth,Nobuhiko Kayagaki,Noriko Yamaguchi,Shigeru Kakuta,Yoichiro Iwakura,Hideo Yagita,Ko Okumura +8 more
TL;DR: It is reported that TRAIL is constitutively expressed on murine natural killer cells in the liver and plays a substantial role in suppressing tumor metastasis and provides the first evidence for the physiological function of TRAIL as a tumor suppressor.
Journal ArticleDOI
Measurement of atmospheric neutrino oscillation parameters by Super-Kamiokande I
Y. Ashie,J. Hosaka,K. Ishihara,Yoshitaka Itow,J. Kameda,Yusuke Koshio,A. Minamino,C. Mitsuda,M. Miura,Shigetaka Moriyama,Masayuki Nakahata,Toshio Namba,R. Nambu,Y. Obayashi,Masato Shiozawa,Yoshihiro Suzuki,Y. Takeuchi,K. Taki,Shinya Yamada,M. Ishitsuka,Takaaki Kajita,K. Kaneyuki,Shoei Nakayama,A. Okada,Ko Okumura,C. Saji,Y. Takenaga,S. Clark,Shantanu Desai,E. Kearns,S. Likhoded,J. L. Stone,L. R. Sulak,W. Wang,M. Goldhaber,David William Casper,J. P. Cravens,W. Gajewski,W. R. Kropp,D. W. Liu,S. Mine,Michael B. Smy,Henry W. Sobel,C. W. Sterner,Mark R. Vagins,K. S. Ganezer,John Hill,W. E. Keig,J. S. Jang,J. Y. Kim,I. T. Lim,Kate Scholberg,C. W. Walter,R. W. Ellsworth,S. Tasaka,G. Guillian,A. Kibayashi,John G. Learned,S. Matsuno,D. Takemori,M. D. Messier,Y. Hayato,A. K. Ichikawa,T. Ishida,T. Ishii,T. Iwashita,Takashi Kobayashi,T. Maruyama,Koji Nakamura,K. Nitta,Yuichi Oyama,Makoto Sakuda,Y. Totsuka,Atsumu Suzuki,Masaya Hasegawa,K. Hayashi,I. Kato,H. Maesaka,Taichi Morita,Tsuyoshi Nakaya,K. Nishikawa,T. Sasaki,S. Ueda,Shoji Yamamoto,Todd Haines,Todd Haines,S. Dazeley,S. Hatakeyama,R. Svoboda,E. Blaufuss,J. A. Goodman,G. W. Sullivan,D. Turcan,Alec Habig,Y. Fukuda,C. K. Jung,T. Kato,Katsuhiro Kobayashi,Magdalena Malek,C. Mauger,C. McGrew,A. Sarrat,E. Sharkey,C. Yanagisawa,T. Toshito,Kazumasa Miyano,N. Tamura,J. Ishii,Y. Kuno,Minoru Yoshida,S. B. Kim,J. Yoo,H. Okazawa,T. Ishizuka,Y. Choi,H. Seo,Y. Gando,Takehisa Hasegawa,Kunio Inoue,J. Shirai,A. Suzuki,Masatoshi Koshiba,Y. Nakajima,Kyoshi Nishijima,T. Harada,Hirokazu Ishino,Y. Watanabe,D. Kielczewska,D. Kielczewska,J. Zalipska,H. G. Berns,R. Gran,K. K. Shiraishi,A. L. Stachyra,K. Washburn,R. J. Wilkes +135 more
TL;DR: In this article, a combined analysis of fully-contained, partially-contained and upward-going muon atmospheric neutrino data from a 1489 d exposure of the Super-Kamiokande detector is presented.
Journal ArticleDOI
Measurements of the solar neutrino flux from Super-Kamiokande's first 300 days
Y. Fukuda,T. Hayakawa,E. Ichihara,Kunio Inoue,K. Ishihara,H. Ishino,Yoshitaka Itow,Takaaki Kajita,J. Kameda,S. Kasuga,K. Kobayashi,Yohei Kobayashi,Yusuke Koshio,K. Martens,M. Miura,Masayuki Nakahata,S. Nakayama,A. Okada,M. Oketa,Ko Okumura,M. Ota,N. Sakurai,Masato Shiozawa,Yasunari Suzuki,Y. Takeuchi,Y. Totsuka,Shinya Yamada,M. Earl,Alec Habig,J. T. Hong,E. Kearns,S. B. Kim,S. B. Kim,M. Masuzawa,M. D. Messier,Kate Scholberg,J. L. Stone,L. R. Sulak,C. W. Walter,M. Goldhaber,T. Barszczak,W. Gajewski,P. G. Halverson,J. Hsu,W. R. Kropp,L. R. Price,Frederick Reines,H. W. Sobel,Mark R. Vagins,K. S. Ganezer,W. E. Keig,R. W. Ellsworth,S. Tasaka,J. W. Flanagan,A. Kibayashi,John G. Learned,S. Matsuno,V. J. Stenger,D. Takemori,T. Ishii,Junichi Kanzaki,T. Kobayashi,K. Nakamura,K. Nishikawa,Yuichi Oyama,A. Sakai,Makoto Sakuda,Osamu Sasaki,S. Echigo,M. Kohama,A. T. Suzuki,Todd Haines,Todd Haines,E. Blaufuss,R. Sanford,R. Svoboda,M. L. Chen,Z. Conner,Z. Conner,J. A. Goodman,G. W. Sullivan,Masaki Mori,Masaki Mori,J. Hill,C. K. Jung,C. Mauger,C. McGrew,E. Sharkey,B. Viren,C. Yanagisawa,W. Doki,T. Ishizuka,T. Ishizuka,Y. Kitaguchi,H. Koga,Kazumasa Miyano,H. Okazawa,C. Saji,M. Takahata,A. Kusano,Y. Nagashima,M. Takita,T. Yamaguchi,Minoru Yoshida,M. Etoh,K. Fujita,Akira Hasegawa,Takehisa Hasegawa,S. Hatakeyama,T. Iwamoto,T. Kinebuchi,M. Koga,T. Maruyama,Hiroshi Ogawa,A. Suzuki,F. Tsushima,Masatoshi Koshiba,M. Nemoto,Kyoshi Nishijima,T. Futagami,Y. Hayato,Y. Kanaya,K. Kaneyuki,Y. Watanabe,D. Kielczewska,D. Kielczewska,R. A. Doyle,J. S. George,A. L. Stachyra,L. Wai,J. Wilkes,K. K. Young +131 more
TL;DR: The first results of the solar neutrino flux measurement from Super-Kamiokande are presented in this article, where the results are obtained from data taken between 31 May 1996, and 23 June 1997.