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307 results on '"Iwasaki, Masashi"'

1. Integrable Systems Related to Matrix LR Transformations

Author

Iwasaki, Masashi, Shinjo, Masato, Yamamoto, Yusaku, Fukuda, Akiko, Watanabe, Sennosuke, Sekiguchi, Masaki, Ishiwata, Emiko, Ikeda, Kazushi, editor, Kawamura, Yoshiumi, editor, Makino, Kazuhisa, editor, Tsujimoto, Satoshi, editor, Yamashita, Nobuo, editor, Yoshizawa, Shintaro, editor, and Sumita, Hanna, editor

Published
2024
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9. Two characteristic polynomials corresponding to graphical networks over min-plus algebra

Author

Watanabe, Sennosuke, Tozuka, Yuto, Watanabe, Yoshihide, Yasuda, Aito, and Iwasaki, Masashi

Subjects
Mathematics - Combinatorics
Abstract

In this paper, we investigate characteristic polynomials of matrices in min-plus algebra. Eigenvalues of min-plus matrices are known to be the minimum roots of the characteristic polynomials based on tropical determinants which are designed from emulating standard determinants. Moreover, minimum roots of characteristic polynomials have a close relationship to graphs associated with min-plus matrices consisting of vertices and directed edges with weights. The literature has yet to focus on the other roots of min-plus characteristic polynomials. Thus, here we consider how to relate the 2nd, 3rd,... minimum roots of min-plus characteristic polynomials to graphical features. We then define new characteristic polynomials of min-plus matrices by considering an analogue of the Faddeev-LeVerrier algorithm that generates the characteristic polynomials of linear matrices. We conclusively show that minimum roots of the proposed characteristic polynomials coincide with min-plus eigenvalues, and observe the other roots as in the study of the already known characteristic polynomials. We also give an example to illustrate the difference between the already known and proposed characteristic polynomials., Comment: 16 pages and one figure

Published
2017

10. Analysis of the Effector Functions of Vδ2 γδ T Cells and NK Cells against Cholangiocarcinoma Cells.

Author

Kulma, Inthuon, Na-Bangchang, Kesara, Carvallo Herrera, Andrea, Ndubuisi, Ifeanyi Theodora, Iwasaki, Masashi, Tomono, Hiromi, Morita, Craig T., Okamura, Haruki, Mukae, Hiroshi, and Tanaka, Yoshimasa

Subjects
ANTIBODY-dependent cell cytotoxicity, KILLER cells, CANCER cells, EPITHELIAL cells, IMMUNE response, T cells
Abstract

Cholangiocarcinoma (CCA) is a rare disease characterized by malignant cells derived from the epithelial cells of the biliary duct system. Despite extensive treatments, the prognosis for CCA remains poor, emphasizing the critical need for the development of novel treatments. Considerable attention has been directed towards innate immune effector cells, which can recognize tumor cells independently of the major histocompatibility complex, laying the foundation for the development of off-the-shelf drugs. In this study, we cultured innate immune cells obtained from the peripheral blood of healthy adults and conducted a comparative analysis of the effector functions against CCA cell lines by Vδ2 γδ T cells and NK cells. This analysis was performed using standard short- and long-term cytotoxicity assays, as well as ELISA for IFN-γ. Vδ2 γδ T cells demonstrated cytotoxicity and IFN-γ production in response to CCA cells in a TCR-dependent manner, particularly in the presence of tetrakis-pivaloyloxymethyl 2-(thiazole-2-ylamino)ethylidene-1,1-bisphosphonate, a bisphosphonate prodrug. In contrast, direct killing and antibody-dependent cellular cytotoxicity were relatively slow and weak. Conversely, NK cells displayed potent, direct cytotoxicity against CCA cells. In summary, both Vδ2 γδ T cells and NK cells show promise as innate immune effector cells for adoptive transfer therapy in the context of CCA. [ABSTRACT FROM AUTHOR]

Published
2024
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12. How Effectively Do Experts Predict Elderly Target-Users of Assistive Devices? Importance of Expert Knowledge in Device Development

Author

Watanabe, Makiko, Washio, Takuya, Iwasaki, Masashi, Arai, Takeshi, Saijo, Miki, Ohashi, Takumi, Goos, Gerhard, Founding Editor, Hartmanis, Juris, Founding Editor, Bertino, Elisa, Editorial Board Member, Gao, Wen, Editorial Board Member, Steffen, Bernhard, Editorial Board Member, Woeginger, Gerhard, Editorial Board Member, Yung, Moti, Editorial Board Member, Marcus, Aaron, editor, and Rosenzweig, Elizabeth, editor

Published
2020
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13. Discrete-time analysis for the integrable discrete Toda equations and the discrete Lotka-Volterra system

Author

Shinjo, Masato, Nakamura, Yoshimasa, Iwasaki, Masashi, and Kondo, Koichi

Subjects
Mathematical Physics, 15A15, 15A18, 37K10, 37K40, 39A12, 40A05, 45M05, 65F15
Abstract

The discrete autonomous/non-autonomous Toda equations and the discrete Lotka-Volterra system are important integrable discrete systems in fields such as mathematical physics, mathematical biology and statistical physics. They also have applications to numerical linear algebra. In this paper, we first simultaneously obtain their general solutions. Then, we show the asymptotic behavior of the solutions for any initial values as the discrete-time variables go to infinity. Our two main techniques for understanding the distinct integrable systems are to introduce two types of discrete-time variables and to examine properties of a restricted infinite sequence, its associated determinants and polynomials., Comment: 26 pages

Published
2016

19. An asymptotic expansion of the Casorati determinant and its application to discrete integrable systems

Author

Shinjo, Masato, Iwasaki, Masashi, and Nakamura, Yoshimasa

Subjects
Mathematical Physics, Mathematics - Dynamical Systems, 39A12, 34E05, 15A15
Abstract

The Hankel determinant appears in the representation of solutions to several integrable systems. Asymptotic expansion of the Hankel determinant thus plays a key role for investigating asymptotic analysis of such integrable system. In this paper, an asymptotic expansion formula of a certain Casorati determinant is presented as an extension of the Hankel case. It is also shown that an application of it to an asymptotic analysis of the discrete hungry Lotka-Volterra system, which is one of basic models in mathematical biology., Comment: 12 pages

Published
2013

22. Monotonic Convergence to Eigenvalues of Totally Nonnegative Matrices in an Integrable Variant of the Discrete Lotka-Volterra System

Author

Tobita, Akihiko, Fukuda, Akiko, Ishiwata, Emiko, Iwasaki, Masashi, Nakamura, Yoshimasa, Barth, Timothy J., Series editor, Griebel, Michael, Series editor, Keyes, David E., Series editor, Nieminen, Risto M., Series editor, Roose, Dirk, Series editor, Schlick, Tamar, Series editor, Sakurai, Tetsuya, editor, Zhang, Shao-Liang, editor, Imamura, Toshiyuki, editor, Yamamoto, Yusaku, editor, Kuramashi, Yoshinobu, editor, and Hoshi, Takeo, editor

Published
2017
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24. Three distinct mechanisms underlying human γδ T cell-mediated cytotoxicity against malignant pleural mesothelioma

Author

Umeyama, Yasuhiro, primary, Taniguchi, Hirokazu, additional, Gyotoku, Hiroshi, additional, Senju, Hiroaki, additional, Tomono, Hiromi, additional, Takemoto, Shinnosuke, additional, Yamaguchi, Hiroyuki, additional, Tagod, Mohammed S. O., additional, Iwasaki, Masashi, additional, Tanaka, Yoshimasa, additional, and Mukae, Hiroshi, additional

Published
2023
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31. SmartContractor: A Distributed Task Assignment System Based on the Simple Contract Net Protocol

Author

Khanal, Bipin, Sugiura, Hideyuki, Ito, Takayuki, Iwasaki, Masashi, Fujita, Katsuhide, Kobayashi, Masao, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, Goebel, Randy, editor, Siekmann, Jörg, editor, Wahlster, Wolfgang, editor, Yang, Jung-Jin, editor, Yokoo, Makoto, editor, Ito, Takayuki, editor, Jin, Zhi, editor, and Scerri, Paul, editor

Published
2009
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32. Accelerating the Singular Value Decomposition of Rectangular Matrices with the CSX600 and the Integrable SVD

Author

Yamamoto, Yusaku, Fukaya, Takeshi, Uneyama, Takashi, Takata, Masami, Kimura, Kinji, Iwasaki, Masashi, Nakamura, Yoshimasa, Hutchison, David, editor, Kanade, Takeo, editor, Kittler, Josef, editor, Kleinberg, Jon M., editor, Mattern, Friedemann, editor, Mitchell, John C., editor, Naor, Moni, editor, Nierstrasz, Oscar, editor, Pandu Rangan, C., editor, Steffen, Bernhard, editor, Sudan, Madhu, editor, Terzopoulos, Demetri, editor, Tygar, Doug, editor, Vardi, Moshe Y., editor, Weikum, Gerhard, editor, and Malyshkin, Victor, editor

Published
2007
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33. Matrix similarity transformations derived from extended q-analogues of the Toda equation and Lotka–Volterra system.

Author

Watanabe, Ryoto, Shinjo, Masato, and Iwasaki, Masashi

Subjects
SIMILARITY transformations, LOTKA-Volterra equations, EIGENVALUE equations, MATRICES (Mathematics)
Abstract

The q-Toda equation is derived from replacing ordinary derivatives with q-derivatives in the famous Toda equation. In this paper, we associate an extension of the q-Toda equation with matrix eigenvalue problems, and then show applications of its time-discretization to computing matrix eigenvalues. With respect to the Lotka–Volterra system, we also have the similar discussion on the case of the Toda equation. [ABSTRACT FROM AUTHOR]

Published
2023
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