Organization
Organization Organization for the Strategic Coordination of Research and Intellectual Properties Professor (non-tenured)
Title
Professor (non-tenured)
External link
Degree
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理学博士 ( 1989.3 東京工業大学 )
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理学修士 ( 1986.3 東北大学 )
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理学士 ( 東京理科大学 )
Research Areas
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Natural sciences / Bio-, chemical, and soft-matter physics
Education
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Tohoku University Graduate School, Division of Natural Science
1984.4 - 1986.3
Country/Region： Japan
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Tokyo University of Science Faculty of Science
1980.4 - 1984.3
Country/Region： Japan
Research History
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Meiji University Professor
2020.4
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Hiroshima University Professor
2019.4 - 2020.3
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Hiroshima University Professor
2005.4 - 2019.3
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Osaka Prefecture University Associate Professor (as old post name)
2000.4 - 2005.3
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Osaka Prefecture University Associate Professor (as old post name)
1998.4 - 2000.3
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コペンハーゲン大学 ニールス・ボーア研究所 客員研究員 客員研究員
1995.10 - 1996.9
Country/Region：Denmark
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Ibaraki University Associate Professor (as old post name)
1995.4 - 1998.3
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Ibaraki University 助手
1991.4 - 1995.3
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Kyoto University
1989.4 - 1991.3
Professional Memberships
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The Physical Society of Japan
Papers
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Sand Influx Effect on Barchan Steady-state Profile Reviewed
Sofia Navarro Yabe, Kojiro Otoguro, Hirokazu Ninomiya, Masashi Shiraishi, Hiraku Nishimori
Journal of the Physical Society of Japan 95 ( 9 ) 2026.9
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Dynamics of Social Balance with Ternary Interpersonal Relationships Reviewed
Hirotaka Goto, Masashi Shiraishi, Hiraku Nishimori, Joshua B. Plotkin
Journal of Social Physics 1 ( 1 ) 1 - 16 2025.12
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Self-organized acoustic behavior in bats arises from simple rules Reviewed International journal
Kazuma Hase, Tasuku Miyazaki, Seiya Oka, Noriyoshi Senoo, Hiraku Nishimori, Masashi Shiraishi, Ken Yoda, Kohta I Kobayasi, Shizuko Hiryu
bioRxiv 2024.11
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Statistical Study of Worker Activity Relying on Location in Ant Colonies Reviewed International journal
Masashi Shiraishi and Hiraku Nishimori
Swarm Intelligence: 14th International Conference, ANTS 2024 LNCS14987 251 - 252 2024.10
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Onset of intragroup conflict in a generalized model of social balance Reviewed International journal
Hirotaka Goto, Masashi Shiraishi, and Hiraku Nishimori
Physical Review Letters 133 127402 2024.9
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Switching particle systems for foraging ants showing phase transitions in path selections Reviewed International journal
Ayana Ezoe, Saori Morimoto, Yuya Tanaka, Makoto Katori, and Hiraku Nishimori
Physica A 643 129798 2024.6
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Can self-propelled objects escape from compression stimulation? Reviewed International journal
Masaki Yoshikai, Muneyuki Matsuo, Nobuhiko J. Suematsu, Hiraku Nishimori, and Satoshi Nakata
Soft Matter d4sm00288ax 3458 - 3463 2024.3
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Co-creation with local governments and ski resorts to generate scientific information that contributes to ski resort avalanche safety management Reviewed International journal
Satoru Yamaguchi, Yoichi Ito, Takahiro Tanabe, Kouichi Nishimura, Satoru Adachi, Sojiro Sunako, Yoshihiko Saito, Tsubasa Okaze, Hirofumi Niiya, Kae Tsunematsu, Hiraku Nishimori
Bulletin of Glaciological Research 42 9 - 17 2024.2
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Characteristics of daily foraging activity of Camponotus japonicus via time series analysis Reviewed International journal
Hiromichi Goko, Osamu Yamanaka, Masashi Shiraishi, and Hiraku Nishimori
Plos One 18 293455 2023.11
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Daily activity time series of ants, Camponotus japonicus Reviewed International journal
Hiromichi Goko, Osamu Yamanaka, Masashi Shiraishi, and Hiraku Nishimori
Dryad 2023.10
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Self‐Propulsion Mode Switching of a Briggs–Rauscher Droplet Reviewed International journal
Masakazu Kuze, Yujin Kubodera, Hiromi Hashishita, Muneyuki Matsuo, Hiraku Nishimori, and Satoshi Nakata
ChemSystemsChem 5 e202200030(1) - e202200030(5) 2023.5
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Ants Alter Collective Behavior After Feeding and Generate Shortcut Paths on a Two-Dimensional Foraging Area Reviewed International journal
Osamu Yamanaka, Yusuke Oki, Yukari Tamura, Masashi Shiraishi, Shunsuke Izumi-Akinori Awazu, and Hiraku Nishimori
Frontiers in Physics 10 2022.5
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Catch and Release Chemotaxi Reviewed International journal
Y. Yasugahira, Y. Tatsumi, O. Yamanaka, H. Nishimori, M. Nagayama, and S. Nakata
ChemSystemsChem 4 e2100031 2022.3
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Influence of Labor Conditions and Interaction Among Individuals on Circadian Activity Rhythms in the Ant Camponotus Japonicus Reviewed International journal
Masashi Shiraishi, Takumi Odan, Osamu Yamanaka, and Hiraku Nishimori
Journal of Robotics and Mechatronics 33 ( 3 ) 582 - 589 2021.6
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Effect of interaction network structure in a response threshold model Reviewed International journal
Masashi Shiraishi, Osamu Yamanaka, and Hiraku Nishimori
Artificial Life and Robotics 27 743 - 750 2020.9
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群体数理技術検討会－新しい産学連携の試み
川本敦史,吉澤真太郎,白石允梓,西森拓
応用数理 30 ( 2 ) 37 - 42 2020.6
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Inversion probability of three-bladed self-propelled rotors after forced stops of different durations Reviewed International journal
Satoshi Nakata, Takero Matsufuji, Jerzy Gorecki, Hiroyuki Kitahata, and Hiraku Nishimori
Phys. Chem. Chem. Phys 23 13123 - 13128 2020.6
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Dead-Water Region around Two-Dimensional Sand-Dune Models Reviewed
Yusuke Fujita, Hiraku Nishimori, and Makoto Iima
J.Phys. Soc. Jpn. 89 ( 6 ) 063901 - 063901 2020.5
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水面滑走する自己駆動粒子のリズム運動 Reviewed
末松 J. 信彦, 池田幸太,西森拓
日本物理学会誌 75 ( 4 ) 215 - 220 2020.4
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Simple Particle Model for Low-Density Granular Flow Interacting with Ambient Fluid Reviewed International journal
Hirofumi Niiya, Akinori Awazu, and Hiraku Nishimori
Geosciences 10 ( 2 ) 69 - 69 2020.2
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Stabilization of a straight longitudinal dune under bimodal wind with large directional variation. Reviewed International journal
Nakao-Kusune Sachi, Sakaue Takahiro, Nishimori Hiraku, Nakanishi Hiizu
Physical review. E 101 ( 1-1 ) 012903 2020.1
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Inversion probability of three-bladed self-propelled rotors after forced stops of different durations Reviewed International coauthorship International journal
Satoshi Nakata, Takero Matsufuji, Jerzy Gorecki, Hiroyuki Kitahata, Hiraku Nishimori
Phys. Chem. Chem. Phys. 22 13123 - 13128 2020
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Dynamical Quorum Sensing in Non-Living Active Matter
Yui Matsuda, Kota Ikeda, Yumihiko Ikura, Hiraku Nishimori, Nobuhiko J. Suematsu
Journal of the Physical Society of Japan 88 ( 9 ) 093002 - 093002 2019.9
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Verification of mathematical models of response threshold through statistical characterisation of the foraging activity in ant societies. International journal
Yamanaka Osamu, Shiraishi Masashi, Awazu Akinori, Nishimori Hiraku
Scientific reports 9 ( 1 ) 8845 2019.6
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Diverse stochasticity leads a colony of ants to optimal foraging. Reviewed International journal
Shiraishi Masashi, Takeuchi Rito, Nakagawa Hiroyuki, Nishimura Shin I, Awazu Akinori, Nishimori Hiraku
Journal of theoretical biology 465 7 - 16 2019.3
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Kazutaka Takao, Kazunori Takamiya, Da-Qiao Ding, Tokuko Haraguchi, Yasushi Hiraoka, Hiraku Nishimori, Akinori Awazu
Journal of the Physical Society of Japan 88 ( 2 ) 023801 - 023801 2019.2
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Impact-induced collapse of an inclined wet granular layer International journal
Shinta Takizawa, Hirofumi Niiya, Takahiro Tanabe, Hiraku Nishimori, Hiroaki Katsuragi
Physica D: Nonlinear Phenomena 386-387 8 - 13 2019.1
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Synchronization of self-propelled soft pendulums. Reviewed International journal
Nakata Satoshi, Kayahara Katsuhiko, Kuze Masakazu, Ginder Elliott, Nagayama Masaharu, Nishimori Hiraku
Soft matter 14 ( 19 ) 3791-3798 2018.5
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Reciprocating Motion of a Self-Propelled Rotor Induced by Forced Halt and Release Operations
Satoshi Nakata, Katsuhiko Kayahara, Hiroya Yamamoto, Paulina Skrobanska, Jerzy Gorecki, Akinori Awazu, Hiraku Nishimori, Hiroyuki Kitahata
The Journal of Physical Chemistry C 122 ( 6 ) 3482 - 3487 2018.2
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Splash detail due to a single grain incident on a granular bed. International journal
Tanabe Takahiro, Shimada Takashi, Ito Nobuyasu, Nishimori Hiraku
Physical review. E 95 ( 2-1 ) 022906 2017.2
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Osamu Yamanaka, Akinori Awazu, Hiraku Nishimori
Journal of the Robotics Society of Japan 35 ( 6 ) 444 - 447 2017
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The 1-Particle-per-k-Nucleotides (1PkN) Elastic Network Model of DNA Dynamics with Sequence-Dependent Geometry. Reviewed International journal
Kameda Takeru, Isami Shuhei, Togashi Yuichi, Nishimori Hiraku, Sakamoto Naoaki, Awazu Akinori
Frontiers in physiology 8 103 2017
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Excluded volume effect enhances the homology pairing of model chromosomes Reviewed
Kazunori Takamiya, Keisuke Yamamoto, Shuhei Isami, Hiraku Nishimori, Akinori Awazu
Nonlinear Theory and Its Applications, IEICE 7 ( 2 ) 66 - 75 2016
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Cellular Automata Automatically Constructed from a Bioconvection Pattern Reviewed
Kawaharada Akane, Shoji Erika, Nishimori Hiraku, Awazu Akinori, Izumi Shunsuke, Iima Makoto
RECENT ADVANCES IN NATURAL COMPUTING 14 15 - 25 2016
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The Flux of Euglena gracilis Cells Depends on the Gradient of Light Intensity. Reviewed International journal
Ogawa Takuma, Shoji Erika, Suematsu Nobuhiko J, Nishimori Hiraku, Izumi Shunsuke, Awazu Akinori, Iima Makoto
PloS one 11 ( 12 ) e0168114 2016
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Bifurcation phenomena of two self-propelled camphor disks on an annular field depending on system length. Reviewed International journal
Nishi Kei, Wakai Ken, Ueda Tomoaki, Yoshii Miyu, Ikura Yumihiko S, Nishimori Hiraku, Nakata Satoshi, Nagayama Masaharu
Physical review. E, Statistical, nonlinear, and soft matter physics 92 ( 2 ) 022910 2015.8
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Synchronized Intermittent Motion Induced by the Interaction between Camphor Disks Reviewed
Nobuhiko J. Suematsu, Kurina Tateno, Satoshi Nakata, Hiraku Nishimori
Journal of the Physical Society of Japan 84 ( 3 ) 034802 - 034802 2015.3
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Variation of Error Strategy of ants Reviewed
Hiraku Nishimori, Rito Takeuchi, Shin I Nishimura, Hiroyuki Nakagawa
Proc.of AROB 20th 879 - 882 2015
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Dynamics of Sand Ripples and Dunes
Hiraku Nishimori
Forma 2015
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Simple Elastic Network Models for Exhaustive Analysis of Long Double-Stranded DNA Dynamics with Sequence Geometry Dependence. Reviewed International journal
Isami Shuhei, Sakamoto Naoaki, Nishimori Hiraku, Awazu Akinori
PloS one 10 ( 12 ) e0143760 2015
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Localized Bioconvection Patterns and Their Initial State Dependency in Euglena gracilis Suspensions in an Annular Container Reviewed
Shoji, Erika, Nishimori, Hiraku, Awazu, Akinori, Izumi, Shunsuke, Iima, Makoto
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 83 ( 4 ) 2014.4
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アリの集団採餌とエラー戦略 Reviewed
西森拓, 西村信一郎
応用数理 24 ( 2 ) 59 - 65 2014
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Collective motion of symmetric camphor papers in an annular water channel. Reviewed International journal
Ikura Yumihiko S, Heisler Eric, Awazu Akinori, Nishimori Hiraku, Nakata Satoshi
Physical review. E, Statistical, nonlinear, and soft matter physics 88 ( 1 ) 012911 2013.7
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Stability of transverse dunes against perturbations: A theoretical study using dune skeleton model
Hirofumi Niiya, Akinori Awazu, Hiraku Nishimori
Aeolian Research 9 63 - 68 2013.6
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Sand dunes as migrating strings
L. Guignier, H. Niiya, H. Nishimori, D. Lague, A. Valance
Physical Review E 87 ( 5 ) 2013.5
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アリの集団採餌における方位情報の選択と切り替え
荻原悠佑, 秋野順治, 西森拓
計測と制御 52 ( 3 ) 201 - 206 2013.3
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Collective motion of symmetric camphor papers in an annular water channel.
Ikura Yumihiko S, Heisler Eric, Awazu Akinori, Nishimori Hiraku, Nakata Satoshi
Collective motion of symmetric camphor papers in an annular water channel. 88 ( 1 ) 2013
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Influences of excluded volume of molecules on signaling processes on the biomembrane. Reviewed International journal
Fujii Masashi, Nishimori Hiraku, Awazu Akinori
PloS one 8 ( 5 ) e62218 2013
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Collective Motion and Phase Transitions of Symmetric Camphor Boats
Eric Heisler, Nobuhiko J. Suematsu, Akinori Awazu, Hiraku Nishimori
Journal of the Physical Society of Japan 81 ( 7 ) 074605 - 074605 2012.7
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Swarming of self-propelled camphor boats. Reviewed International journal
Heisler Eric, Suematsu Nobuhiko J, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 85 ( 5 Pt 2 ) 055201 2012.5
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Segregation-pattern reorientation of a granular mixture on a horizontally oscillating tray. Reviewed International journal
Fujii Masashi, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 85 ( 4 Pt 1 ) 041304 2012.4
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Bifurcation analysis of the transition of dune shapes under a unidirectional wind. Reviewed International journal
Niiya Hirofumi, Awazu Akinori, Nishimori Hiraku
Physical review letters 108 ( 15 ) 158001 2012.4
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Pattern formation of granular avalanches simulated by particle method with hydrodynamics interaction Reviewed
H. Niiya, A. Awazu, H. Nishimori
Proceedings of the 23rd International Congress of Theoretical and Applied Mechanics FS08-13 2012
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Effective stochastic resonance of coupled excitable elements under noise of unequal amplitude. Reviewed International journal
Kawai Ryosuke, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 84 ( 2 Pt 1 ) 021135 2011.8
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Localized Bioconvection of Euglena Caused by Phototaxis in the Lateral Direction Reviewed
Suematsu, Nobuhiko J, Awazu, Akinori, Izumi, Shunsuke, Noda, Shuhei, Nakata, Satoshi, Nishimori, Hiraku
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 ( 6 ) 2011.6
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Atsunari Katsuki, Macoto Kikuchi, Hiraku Nishimori, Noritaka Endo, Keisuke Taniguchi
Earth Surface Processes and Landforms 36 ( 3 ) 372 - 382 2011.2
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数値実験と水槽実験で解くバルハン集団のダイナミクス Reviewed
勝木厚成, 西森拓, 遠藤徳孝, 谷口圭輔
地質学雑誌 117 ( 3 ) 155 - 162 2011
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Effective stochastic resonance under noise of heterogeneous amplitude. Reviewed International journal
Kawai Ryosuke, Torigoe Shogo, Yoshida Kazuhiro, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 82 ( 5 Pt 1 ) 051122 2010.11
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Saddle-node bifurcation to jammed state for quasi-one-dimensional counter-chemotactic flow. Reviewed International journal
Fujii Masashi, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 82 ( 1 Pt 2 ) 015102 2010.7
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Three-dimensional dune skeleton model as a coupled dynamical system of two-dimensional cross sections Reviewed
Niiya Hirofumi, Awazu Akinori, Nishimori Hiraku
Journal of the Physical Society of Japan 79 ( 6 ) 63002 - 1〜4 2010.6
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Collective behavior of inanimate boats. International journal
Suematsu Nobuhiko J, Nakata Satoshi, Awazu Akinori, Nishimori Hiraku
Physical review. E, Statistical, nonlinear, and soft matter physics 81 ( 5 Pt 2 ) 056210 2010.5
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Collective behavior of inanimate boats.
Suematsu Nobuhiko J, Nakata Satoshi, Awazu Akinori, Nishimori Hiraku
Collective behavior of inanimate boats. 81 ( 5 Pt 2 ) 2010
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Saddle-node bifurcation to jammed state for quasi-one-dimensional counter-chemotactic flow Reviewed International journal
Fujii Masashi, Awazu Akinori, Nishimori Hiraku
Physical Review E 82 ( 2 ) 15102 - 1-01510 2010
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砂丘のダイナミクス （解説）
勝木 厚成, 西森 拓
日本物理学会誌 65 ( 12 ) 953 - 960 2010
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Coupled ODEs Model for the Collision Process of Barchan Dunes Reviewed
NISHIMORI Hiraku, KATSUKI Atsunari, SAKAMOTO Hiromi
Theoretical and Applied Mechanics Japan ( 57 ) 179 - 184 2009
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Counter Chemotactic Flow in Quasi-One-Dimensional Path Reviewed
Fujii Masashi, Awazu Akinori, Nishimori Hiraku
Journal of the Physical Society of Japan 78 ( 7 ) 73801 - 73801 2009
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衝突時における三日月型砂丘の動力学 Reviewed
勝木厚成, 西森拓, 遠藤徳孝, 谷口圭輔
ながれ 5 - 14 2008
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走化性を考慮した複数車線交通流 Reviewed
藤井雅史, 西森拓, 粟津暁紀
第14回交通流のシミュレーション シンポジウム論文集 93 - 96 2008
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Collision Dynamics of Two Barchan Dunes Simulated Using a Simple Model
Katsuki Atsunari, Nishimori Hiraku, Endo Noritaka, TANIGUCHI Keisuke
Journal of the Physical Society of Japan 74 ( 2 ) 538 - 541 2005.2
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Flexible Foraging of Ants under Unsteadily Varying Environment Reviewed
Tao Tomomi, Nakagawa Hiroyuki, Yamasaki Masato, Nishimori Hiraku
Journal of the Physical Society of Japan 73 ( 8 ) 2333 - 2341 2004.8
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Adaptive trail formation under dynamics feeding Reviewed
Tao, T., Nakagawa, H., Yamasakia M., Nishimori, H.
Proc.of AROB 8 673 - 676 2003
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On the shape and migration speed of a proto‐dune Reviewed
Hiroshi Momiji, Hiraku Nishimori, Steven R. Bishop
Earth Surface Processes and Landforms 27 ( 12 ) 1335 - 1338 2002.9
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A simple model for the formation of vegetated dunes Reviewed
Hiraku Nishimori, Hirohisa Tanaka
Earth Surface Processes and Landforms 26 ( 10 ) 1143 - 1150 2001.9
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Axial Migration of Two Species in a Horizontal Cylinder Reviewed
M.Nakagawa, A.Awazu, H.Nishimori
Proc.of IUTAM Symposium on Segregation in Granular Flow 163 - 169 2000
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Contact Percolation Process: Contact Process on a Destructed Lattice
Tao Tomomi, Tainaka Kei-ichi, Nishimori Hiraku
Journal of the Physical Society of Japan 68 ( 2 ) 326 - 329 1999.2
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A Simple Model for the Various Pattern Dynamics of Dunes Reviewed
Hiraku Nishimori, Masato Yamasaki, Ken Haste Andersen
International Journal of Modern Physics B 12 ( 03 ) 257 - 272 1998.1
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A minimam model approah for the various pattern dynamics of dunes Reviewed
Nishimori, H., Yamasaki, M.
Proc.NATO ASI 'Physics of Dry Granular Media', NATA ASI series E 350 1998
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Modeling of wind-blown sand using cellular automata
Noriyuki Bob Ouchi, Hiraku Nishimori
Physical Review E 52 ( 6 ) 5877 - 5880 1995.12
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HAYAKAWA Hisao, NISHIMORI Hiraku, SASA Sin'ichi, TAGUCHI Y-h
Japanese journal of applied physics. Pt. 1, Regular papers & short notes 34 ( 2 ) 397 - 408 1995.2
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パターンによる現象の解析―砂丘のダイナミクス
西森 拓
鉱物学雜誌 24 ( 2 ) 77 - 81 1995
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砂の表面のパターン動力学 Reviewed
西森 拓
表面科学 16 ( 4 ) 267 - 272 1995
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Is a black hole accretion disk in a self-organized critical state? Reviewed
S. Mineshige, M. Takeuchi, H. Nishimori
The Astrophysical Journal 435 L125 - L125 1994.11
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On the Generation of 1/f Fluctuations in X-Rays from Black-Hole Objects Reviewed
Mineshige Shin, Ouchi N.Bob, Nishimori Hiraku
Publications of the Astronomical Society of Japan 46 ( 1 ) p97 - 105 1994.2
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Formation of ripple patterns and dunes by wind-blown sand
Hiraku Nishimori, Noriyuki Ouchi
Physical Review Letters 71 ( 1 ) 197 - 200 1993.7
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Spatial pattern formation on interstellar medium
Tainaka, K., Fukazawa, S., Nishimori, H., Yokosawa, M., Mineshige S.
Astrophysics and Space Science 210 117 - 120 1993
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Evolution of soft domains in two-phase alloys: shape changes, surface instability, and network formation Reviewed
Hiraku Nishimori, Akira Onuki
Physics Letters A 162 ( 4 ) 323 - 326 1992.2
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Moderate Pattern and Pinning effect in Phase-Separating alloys Reviewed
Nishimori,H., Onuki, A.
AIP.Conf.Proc.25 6 525 - 528 1992
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相分離過程における弾性効果の数値解析 Reviewed
西森拓, 小貫明
統計数理, 38 213 - 226 1992
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Anomalously slow domain growth due to a modulus inhomogeneity in phase-separating alloys
Akira Onuki, Hiraku Nishimori
Physical Review B 43 ( 16 ) 13649 - 13652 1991.6
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Freezing of Domain Growth in Cubic Solids with Elastic Misfit Reviewed
Nishimori Hiraku, Onuki Akira
Journal of the Physical Society of Japan 60 ( 4 ) p1208 - 1211 1991.4
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On Eshelby′s Elastic Interaction in Two-Phase Solids Reviewed
Onuki Akira, Nishimori Hiraku
Journal of the Physical Society of Japan 60 ( 1 ) p1 - 4 1991.1
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Pattern formation in phase-separating alloys with cubic symmetry
Hiraku Nishimori, Akira Onuki
Physical Review B 42 ( 1 ) 980 - 983 1990.7
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17. MODULATED PATTERNS AND PINNING EFFECT IN PHASE-SEPARATING ALLOYS :
Onuki Akira, Nishimori Hiraku
物性研究 54 ( 4 ) 1990
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A computational Study of Defects Dynamics of a 3-Dimensional Quenched Complex Field Reviewed
Nishimori Hiraku, Nukii Tomohiro
Journal of the Physical Society of Japan 58 ( 2 ) 563 - 570 1989
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A Numerical Study of Defect Dynamics in a Three-Dimensional Complex Field Reviewed
Hiraku Nishimori, T. Nukii
J.Phys.Soc.Jpn 58 563 - 570 1989
Books
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地形現象のモデリング : 海底から地球外天体まで
遠藤 徳孝, 小西 哲郎, 西森 拓, 水口 毅, 柳田 達雄（ Role： Joint author）
名古屋大学出版会 2017.10
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Mathematical approaches to biological systems : networks, oscillations, and collective motions Reviewed
（ Role： ContributorSwitching of Primarily Relied Information by Ants: A Combinatorial Study of Experiment and Modeling）
Springer 2015 （ ISBN:9784431554431 ）
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松下 貢, 平田 森三, 丘 英通, 寺田 寅彦, 佐々 真一, 佐野 雅己, 西森 拓, 近藤 滋（ Role： Joint author第2部第３節 風紋と砂丘）
岩波書店 2014 （ ISBN:9784000296205 ）
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行動生物学辞典
上田, 恵介, 岡ノ谷, 一夫, 菊水, 健史, 坂上, 貴之, 辻, 和希, 友永, 雅己, 中島, 定彦, 長谷川, 寿一, 松島, 俊也（ Role： Contributor）
東京化学同人 2013.11 （ ISBN:9784807908370 ）
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応用数理ハンドブック
薩摩, 順吉, 大石, 進一, 杉原, 正顕, 日本応用数理学会（ Role： Contributor）
朝倉書店 2013.10 （ ISBN:9784254111415 ）
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現象数理学入門
三村, 昌泰（ Role： Contributor第2章）
東京大学出版会 2013.9 （ ISBN:9784130629164 ）
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形の科学百科事典
形の科学会（ Role： Contributor）
朝倉書店 2013.4 （ ISBN:9784254102642 ）
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「行動・進化」の数理生物学
日本数理生物学会, 瀬野, 裕美（ Role： Contributor第5章 アリの採餌ダイナミクスと数理モデル）
共立出版 2010.2 （ ISBN:9784320057029 ）
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自己組織化ハンドブック
下村, 政嗣, 山口, 智彦, 国武, 豐喜（ Role： Contributor）
エヌ・ティー・エス 2009.11 （ ISBN:9784860432645 ）
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量子渦のダイナミクス : 砂丘と風紋の動力学
坪田, 誠, 西森, 拓（ Role： Joint author）
培風館 2008.7 （ ISBN:9784563023416 ）
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Concepts and modelling in geomorphology : international perspectives
Evans, Ian S.（ Role： Contributor）
TERRAPUB 2003 （ ISBN:4887041322 ）
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複雑系の事典 : 適応複雑系のキーワード150
「複雑系の事典」編集委員会（ Role： Contributor）
朝倉書店 2001.2 （ ISBN:4254101694 ）
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粉粒体の物理学
西森 拓, 早川 尚男, 田口 善弘（ Role： Joint author）
日本物理学会 1999.9
MISC
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Interacting Particle Systems Modeling Self-Propelled Motions International journal
Saori Morimoto, Makoto Katori, Hiraku Nishimori
arXiv 2502.08543 2025.2
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Extinction and Metastability of Pheromone-Roads in Stochastic Models for Foraging Walks of Ants International journal
Saori Morimoto, Makoto Katori, Hiraku Nishimori
arXiv 2502.09475 2025.2
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Three-Dimensional Dune Skeleton Model as a Coupled Dynamical System of Two-Dimensional Cross Sections (vol 79, 063002, 2010)
Hirofumi Niiya, Akinori Awazu, Hiraku Nishimori
JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN 80 ( 7 ) 2011.7
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蟻の採餌ダイナミクスと数理モデリング (生物現象に対するモデリングの数理) Reviewed
西森 拓
数理解析研究所講究録 ( 1653 ) 2 - 2 2009.6
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計算機による地形動力学の研究
西森 拓
2007
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バルハン砂丘群のネットワーク形成とサイズ分布 (複雑流体の構造形成と崩壊の数理 研究集会報告集) Reviewed
寺田 昌弘, 西森 拓
数理解析研究所講究録 ( 1413 ) 15 - 25 2005.2
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環境変化下での蟻集団のトレイル戦略評価 Reviewed
田尾知巳,中川寛之,西森拓
数理解析研究所講究録「複雑流体の構造形成と崩壊の数理」 143 2005
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多様な環境下での砂丘の動力学に関する研究
西森 拓
科研費基盤C実績報告書 2002
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川の蛇行 網状転移 (複雑流体の数理2)
柳田 達雄, 西森 拓, 小西 哲郎
数理解析研究所講究録 ( 1184 ) 30 - 40 2001.1
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植物の成長を考慮した砂丘の模型 (複雑流体の数理2)
西森 拓, 田仲 浩久
数理解析研究所講究録 ( 1184 ) 41 - 49 2001.1
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粉粒体の物理学
西森拓, 早川尚男, 田口善弘
新装版物理学論文選集シリーズ 1999.9
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粉体の物理とパターン形成
早川 尚男, 西森 拓, 佐々 真一, 田口 善弘
日本物理学会誌 49 ( 1 ) 18 - 25 1994
Presentations
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Diversity of Workload and Function of Errors in Ant Colonies
Hiraku Nishimori
Oxford-Japan Symposium on Cell Behaviors in Simple to Complex Environments 2025.9
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Reproduction of spatial patterns of snow dimples using a simple computational model
Hiraku Nishimori, Masashi Shiraishi, Takahiro Tanabe, Satoru Yamaguchi
BACO2025(Busan IAMAS-IACS-IAPSO Joint Assembly) 2025.7
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個のダイナミクスから集団のロジックへ —アリ集団の行動測定と理論解析– Invited
西森拓
システム行動学研究会 2025.5
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リーダー無しの協調行動 ~アリ社会の知恵を簡単な行動実験と数理モデルで紐解く Invited
西森拓
日本地球惑星科学連合2025年大会 2025.5
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Non-Uniformity of Workload and Errors in Ant Colonies Invited
Hiraku Nishimori
Symposium: Adaptive behavior and its ecological foundations 2025.2
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Autonomous Workload Regulation in Ant Colonies --- A Combinational Study of Experiment and Modeling
Hiraku Nishimori
Mini Symposium on ‘Determinantal Point Processes, Quantum Mechanics and Signal Analysis 2024.7
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Dynamics of Error and Compensation Learned from Social Insects Invited
Hiraku Nishimori
2024.2
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Autonomous Workload Regulation Mechanism in Foraging Ants
Hiraku Nishimori
6th Yamada Symposium on“Diversity of Biological Patterns and Forms in Nature: toward a Comprehensive Understanding 2023.8
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Smart Collective Design by Simple Individuals: Elucidating Ant Social Behavior Through Behavioral Tracking and Mathematical Modeling Invited
Hiraku Nishimori
2023.1
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Systematic Analysis of Collective Dynamics in Ant Colonies via Long-Term Tracking with Individual Identification Invited
Hiraku Nishimori
2022.9
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Intelligent Group Behavior by a Mass of Un-intelligent Individuals Invited
Hiraku Nishimori
2022.7
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Modelling Autonomous Workload Distribution in Ant Colonies Invited
Hiraku Nishimori
Crossroad of Statistical Physics and Probability Theory 2022.6
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Collective Motion of Self-Propelled Camphor Particles Invited
Hiraku Nishimori
RHINO2021：APCTP Asia Pacific Center for Theoretical Physics 2021.8
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Smart Collective Design by Simple Individuals: Elucidating Ant Social Behavior Through Data and Mathematical Modeling Invited
Hiraku Nishimori
2020.11
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Smart Collective Design Without a Leader: Elucidating Ant Social Behavior Through Data and Mathematical Modeling Invited
Hiraku Nishimori
2020.11
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Intelligent Group Behavior by Un-intelligent Individuals, Autonomous Task Allocation Dynamics of Foraging Ants
Hiraku Nishimori
2020.11
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Measurement and Mathematical Modeling of Ant Societies
Hiraku Nishimori
2020.8
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On Autonomous Workload Compensation in Ant Colonies II Invited
Hiraku Nishimori
2020.7
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Organizational Dynamics of Swarms: Insights from Ant Foraging Experiments and Modeling Invited
Hiraku Nishimori
2020.7
Works
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Extinction and Metastability of Pheromone-Roads in Stochastic Models for Foraging Walks of Ants
Saori Morimoto, Makoto Katori, Hiraku Nishimori
2025.2
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Interacting Particle Systems Modeling Self-Propelled Motions
Saori Morimoto, Makoto Katori, Hiraku Nishimori
2025.2
Research Projects
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Experimental and Theoretical Studies on the Flow of Objects and Knowledge, Drawing Insights from Animal Societies
Grant number：26K00677 2026.4 - 2030.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Grant amount：\18330000 （ Direct Cost: \14100000 、 Indirect Cost：\4230000 ）
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Development of odor sensing system based on artificial sniffing
Grant number：24K22324 2024.6 - 2026.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Research (Exploratory)
Grant amount：\6500000 （ Direct Cost: \5000000 、 Indirect Cost：\1500000 ）
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Hierarchical Bio-Navigation Integrating Cyber-Physical Space
Grant number：21H05293 2021.9 - 2026.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A)
Grant amount：\95810000 （ Direct Cost: \73700000 、 Indirect Cost：\22110000 ）
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Systematic Analysis of Dynamics inside Ant-Colonies through Long-Term Measurement with Individual Identification
Grant number：21H05297 2021.9 - 2026.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Transformative Research Areas (A)
Grant amount：\102570000 （ Direct Cost: \78900000 、 Indirect Cost：\23670000 ）
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Hazard Map based on Numerical snow Avalanche model and Spatio-temporal variation of snow
Grant number：21H04601 2021.4 - 2026.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A)
Grant amount：\41860000 （ Direct Cost: \32200000 、 Indirect Cost：\9660000 ）
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Experimental and theoretical studies on flexible and robust organization and functional expression learned from social insects
Grant number：20H01871 2020.4 - 2024.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Nishimori Hiraku
Grant amount：\17680000 （ Direct Cost: \13600000 、 Indirect Cost：\4080000 ）
In this study, we obtained large-scale data on foraging behavior of ant colonies using an individual identification behavior measurement system, and clarified the dynamics of higher-order organizational behavior (e.g., dynamics of task division of labor) in the colonies.In parallel, we revised a previous model (response threshold model) that qualitatively describes the working hypothesis on the generation mechanism of the division of labor, and successfully estimated the response threshold distribution for foraging (the distribution of sensitivity to foraging tasks in the colony) by combining it with the foraging behavior data described above.In addition, we used a non-living self-driven system constructed by physicochemical methods to mimic and analyze the dynamics of complex behaviors of living creatures (e.g., oscillation, round-trip to a target, emergency group evacuation), paving the way for the mechanistic analysis of organizational behavior from the non-living side.
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Integrated Study from Experiment, Theory and Data Analysis on Emerging Mechanism of Collective Functions by Social Insects
Grant number：16H04035 2016.4 - 2020.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
Nishimori Hiraku
Grant amount：\17550000 （ Direct Cost: \13500000 、 Indirect Cost：\4050000 ）
The purpose of this study was to clarify the mechanism of the sophisticated organizational behavior in ant colonies by combining experimental and theoretical methods. As a first step, we succeeded in constructing a new automatic measurement system in which we attached fine RFID tags to all ants in the colony and continuously recorded individual foraging behavior in PC for several months. After that, using this system, we obtained large-scale foraging behavioral data and clarified the followings; i) A hierarchical structure in which a large part of workload was carried by a small number of hard workers within the colony. ii) Hierarchical structure lasts for about a month, after which the working order changes significantly. iii) Swap is seen as a collective behavior of many individuals.
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Oscillatory Motion of Collective Self-Propelled Particles
Grant number：16K05486 2016.4 - 2019.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
Suematsu Nobuhiko, Nakata Satoshi, Matsuda Yui
Grant amount：\4680000 （ Direct Cost: \3600000 、 Indirect Cost：\1080000 ）
Self-propelled particles is the object what spontaneously moves using chemical energy. A camphor disk is one of the self-propelled particle that slides on water. We previously observed mode bifurcation of camphor motion with change in the number of disks. However, its mechanism is under investigation. In this project, we approached this problem from both experimentally and mathematically. For simplify the system, the number of disk was fixed, and the area of water surface was sequentially varied. As the results, similar mode bifurcation was observed, i.e., continuous motion in large area, oscillatory motion in middle area, and stationary state in small area. This mode bifurcation for a single disk was successfully reproduced using mathematical model that was obtained with modified the typical model for camphor motion. Our mathematical approach indicated that oscillatory motion is appeared by instability of continuous motion.
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Full-scale avalanche experiments and development of hazard map with PCQ
Grant number：15H02992 2015.4 - 2019.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B)
NISHIMURA KOUICHI
Grant amount：\17810000 （ Direct Cost: \13700000 、 Indirect Cost：\4110000 ）
Systematic full-scale avalanche experiments have been carried out in Niseko, Hokkaido. Several video cameras were used to investigate the flow behavior. Further, drones were applied not only to record the avalanche motion but to create the digital elevation models for the pre- and post-avalanche events. In order to record the internal motion of avalanches, inertial measurements units (IMU) were also set. Seismometers and infrasound microphones were also set close to the avalanche path. Furthermore, a Doppler radar and an infrared camera were introduced. Obtained results revealed that the combination of different data is effective measures to characterize their structures.
Further, we draw the snow avalanche hazard map in the study area with taking into account the uncertainty of the model input parameters: volume, bed friction angle and the position of the release. We introduced the Polynomial Chaos Quadrature method (PCQ) and probability of the avalanche arrival was evaluated. -
Elucidation of Autonomously Emerging Mechanism of Collective Dynamical Modes Accompanied by Group Functions in Ant Colonies
Grant number：26610117 2014.4 - 2017.3
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Challenging Exploratory Research
Nishimori Hiraku
Grant amount：\3770000 （ Direct Cost: \2900000 、 Indirect Cost：\870000 ）
In this study, by means of quantitative experiments and mathematical modeling for foraging behavior, we elucidated the mechanism through which group of ants without specific leader are able to perform sophisticated collective behavior and flexible task allocation and to get advanced functions. We got following results; 1.In each colony hierarchy for the foraging frequency among ants exists.
2.If active foraging ants are removed from a colony, a part of remaining ants get more active to compensate the activity of removed ants. 3.The rank order of foraging activity among a colony of ants does not greatly change in short time range but shows a remarkable change in long range of time. -
Collective motion of self-propelled particles
Grant number：23740299 2011 - 2012
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Young Scientists (B)
SUEMATSU Nobuhiko
Grant amount：\4550000 （ Direct Cost: \3500000 、 Indirect Cost：\1050000 ）
Collective motion is one of the hot topic in an interdisciplinary research field. Collection of camphor boats exhibits spacio-temporal pattern on a ring-shaped water channel. To clarify the mechanism in detail, we measured the basic parameters such as supply and sublimation rate of camphor molecules. Based on our measurement, we estimated the relaxation distance of camphor surface concentration behind the boat. This distance tells us the interaction between the boats. Next, we observed collective behavior of camphor disks on circular water surface, in order to discover novel collective motion. As the result, we successfully found intermittent motion of camphor disks with high number density. This behavior is novel collective motion induced by interaction between the disks.
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Dynamics and Functions of Diverse Multi-Element Systems Accompanied by Fluctuation
Grant number：22540391 2010 - 2012
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
NISHIMORI Hiraku, NAKATA Satoshi, AWAZU Akinori, SUEMATSU Nobuhiko, AKINO Toshiharu
Grant amount：\4290000 （ Direct Cost: \3300000 、 Indirect Cost：\990000 ）
Complex dynamics of various self-propelled multi-element systems has been studied through combinations of experiments, data-analysis and mathematical modeling. In particular, the roles of fluctuation and the diversity in individual systems have carefully been investigated, and some basic mechanisms shared by different systems have been uncovered.
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種々のゆらぎのもとでの非一様要素系の安定動作機構の解明
Grant number：19654056 2007 - 2009
日本学術振興会 科学研究費助成事業 挑戦的萌芽研究
西森 拓, 秋野 順治
Grant amount：\3300000 （ Direct Cost: \3300000 ）
本課題のこれまでの研究で,複数の要素からなるシステムの内部に,ゆらぎが大きく単独では外部刺激への適切な応答などの種々の機能を果たすことが困難な個を導入することで,全体として却って機能が向上するシステムが,多くのシステム,具体的には蟻集団や結合神経系などで存在し得ることを数理模型によって示し,これらの間の共通の論理を探索してきた.今年度は
○これまでの研究に引き続き集団の機能の評価関数として蟻集団の採餌効率を設定し、フェロモンへの走化性に関する「鈍感蟻」の混入量の最適比率、「鈍感蟻」の最適鈍感度などを数値計算によってシステムティックに探求する。
○理論模型と相補的な形での蟻の採餌トレイル(隊列)形成の実験的研究がどこまで可能であるか検討し、具体的な実験をおこなう。
○確率共鳴の原理を応用して,人工内耳にノイズを加えることで聴覚補助性能を向上させることを目標にあげ,おもに次の結果を得た.
1. 従来の正常蟻と鈍感蟻2種混合コロニーでの採餌効率の計算を拡張して,正常蟻,鈍感蟻,弱鈍感蟻3種混合コロニーでの採餌効率を数理模型を通じて調べた.その結果,採餌効率に関しては,正常蟻と鈍感蟻を適当な比率で混合し,弱鈍感蟻はを加えないコロニーが最大の採餌率を達成することがわかった.すなわち,システムのゆらぎの大きい個を一定割合加えることが重要であるが.これをゆらぎの小さい個の混合で代用することできないという結果を得た.
2. 蟻の運動やそのゆらぎ.および,複数蟻間の相互作用の関係を実測するためのシステム実験システムを構築し,画像解析により,単体の蟻を容器の中で孤立させた場合と複数の蟻を容器の中に配置した場合の行動様式の違いを定量化し,一定の違いがあることを示した.
3. 複数神経素子からなる確率共鳴のシステムを数理模型として構築し,システムが素子毎に異なる非一様ノイズによって外部からの刺激への応答度が高まることを示した.
これらは学会などで発表した.また.著書に本課題に関する昨年までの研究成果を記した. -
Computational Study on the dynamics of geomorphology
Grant number：16605008 2004 - 2006
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
NISHIMORI Hiraku, KONISHI Tetsuro, MIZUGUCHI Tsuyoshi, YANAGITA Tatsuo
Grant amount：\3800000 （ Direct Cost: \3800000 ）
Through this project we obtained following two main results
i) Collision dynamics of two barchan dunes is simulated through a newly introduced computational model, which qualitatively reproduced all types of barchan collision; 1. coalescence, 2. ejection 3. split, observed in rescaled water tank experiments. In addition, we further simplified the above cell Model to a set of differential equations, and confirmed that the latter nicely describes the collision dynamics within the 2D cross-section parallel to the wind direction.
ii) Pattern Dynamics of directional crack propagation in a bulk of solid is studied through experiments and phenomenological modeling. The experiments are realized by drying a bulk of starch-water mixture and measuring the water content distribution using MR instruments. Also, the cross section with polygonal structure is visualized and the depth dependency of cell size is measured. These results are compared with a newly introduced phenomenological model. -
地形進化の非線形動力学的視点からの研究
Grant number：14654067 2002 - 2003
日本学術振興会 科学研究費助成事業 萌芽研究
西森 拓, 柳田 達雄, 小西 哲郎, 水口 毅
Grant amount：\3500000 （ Direct Cost: \3500000 ）
今年度は、1.砂丘の水槽実験に関わる研究者と共同し,バルハン砂丘の衝突過程について新たな知見を得た。2.また,2年間の研究の総括として地形の動力学全般に関しての理論模型のあり方と今後の展開の方向性について検討した。
1の砂丘の動力学については、水槽実験と理論計算の比較を行った。とくに世界で最初の水底バルハン砂丘衝突を実現した実験家(大阪大・遠藤氏)らと共同し,バルハン砂丘衝突過程を再現する2D数値模型を構成するとともに、一次元衝突を模型化した3変数力学系を構成し論文を投稿した(Collision dynamics of two barchan dunes simulated by a simple mode, A.Katsuki, H.N., N.Endo, K.Taniguch, cond-mat/0403312)。また一次元衝突の3変数力学系に関して他の研究者(テキサス州立大・V.Poutkaradze氏ら)と理論解析を開始した。
上記2に関しては、研究会(「動力学視点からの地形進化の動力学」京都大学)を主催し、本研究組織以外の関連研究者も集めて地形全般についての情報の交換と地形動力学のあり方について考えた。具体的な話題は、砂丘の動力学、火山噴火のダイナミクス、火星表面地形のダイナミクス、黄土高原地形のダイナミクスなど極めて広範におよんでいるが、共通の問題点として
○(従来、主に地形研究者が行ってきたような)個別な地形形成の事例に対するモデリングが個別の事例のを超えて普遍的な地形現象の理解に役立つか。その場合どのようにモデルを構成するべきか。
○(地球内部や火星表面など)観測不能/困難な部分をもつ地形現象を模型化して行く際、見えない部分を「逆問題」としてどのように解釈し、模型に組み入れていくか。
があげられ討論を行った。これらの問題は最終決着はしていないが、萌芽研究の趣旨に沿って、今後より広範囲の研究者による地形動力学研究の共同作業へ移行するための基本問題を提示することになった。研究会での発表・討論の内容は「物性研究」に掲載される予定である。
さらに、砂丘の動力学一般に関しては関連研究を広く調査収集し、来年出版予定の単行本(量子渦のダイナミクス/粉体と砂丘の力学(共著)朝倉書店)で学生(学部後期・大学院生対象)や研究者一般に地形進化の研究を広く紹介する準備を進めた。 -
A Study for the Dynamics of Dunes in Various Environment
Grant number：11837017 1999 - 2001
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (C)
NISHIMORI Hiraku
Grant amount：\3600000 （ Direct Cost: \3600000 ）
In this project, using computer simulations and theoretical analysis, we investigated the pattern formation process of dunes and their dynamics in various environment.
Specifically, i) pattern selection mechanism of dunes under unsteady wind, ii) pattern formation of dunes in semi-arid region, iii) dynamics of interacting barchans, and, iv) pattern dynamics of river channels, are intensively studied.
For these respective subjects, we found that i) the selection mechanism of dunes' trend under unsteady wind is simply explained by the superposition of linearly unstable modes, ii) the formation of vegetated dunes, especially parabolic, are simulated using a inter-suppression dynamics between plant growth and sand transport. iii) size distribution of barchans can simply be explained using the group-dynamics of dunes. iv) dynamics of river channel is treatable using a similar model as that for dunes.
Through the research process of these subjects, we got fundamental methodology for the unified mathematical treatment of various geo-morphological processes, which is the next issue of our study. -
砂の静力学と動力学
Grant number：09740303 1997 - 1998
日本学術振興会 科学研究費助成事業 奨励研究(A)
西森 拓
Grant amount：\2400000 （ Direct Cost: \2400000 ）
本研究において、砂の動力学でも特に砂丘と風紋の運動に関して、簡単な動力学模型を提案した。この模型に基づいて計算機実験を実行し、バルハン砂丘星型砂丘、セイフ砂丘、横列砂丘など観測から広く知られている砂丘の典型的形状を、Wassonらの観測報告(1983,Nature,Vol.304,p337)と同様の環境変数のもとで再現することに成功した。さらに、時間に依存して2つの方向から風が吹くときの相対角および相対強度と、そのもとで形成される砂丘の尾根の方向の関係について観測事実、および風紋の尾根に関するRubinらの実験報告(1983,Science Vol.237,p276)、計算機実験によって再現した。また、上の実験事実から提案された仮説、すなわち、尾根への垂直な成分の砂輸送が最大になるように尾根の方向が選ばれるという、いわゆる、「miximum gross bed from-normal transport」仮説の理論的裏付けに成功した。
これらの研究内容は、次の欄に記された発表論文の中で報告された他、2度の国際研究集会(リヨン市、および、コペンハーゲン市)における招待講演として発表された。さらに、研究資料収集、および研究推進の中で得られた知見を生かして,日本物理学会から刊行予定の粉体の物理に関する論文選集の編集および解説の執筆を行っている。また、植生を考慮した砂丘の動力学模型を構築中であり、砂表面の一部に植物が生えたとき出現する砂丘の形状を再現する予備的な数値計算に成功した。 -
砂表面のパターン動力学
Grant number：06740313 1994
日本学術振興会 科学研究費助成事業 奨励研究(A)
西森 拓
Grant amount：\1200000 （ Direct Cost: \1200000 ）
本年度表記課題のもと、主に風紋形成の非線形動力学、および、砂丘形成の動力学の研究を進めてきた。手法としては連結写像格子と呼ばれる数値的方法を用い、様々な条件のもとで、風紋や砂丘ができあがる過程を再現した。
先の風紋形成のシミュレーションと線形解析では、風がある敷居値以上の強さになると風紋の周期構造生成されることを示したが、今回は、風がさらに強い場合、系の非線形性が強まり、線形解析では得られない現象が見られようになることを示した。具体的にはコントロールパラメータ(風の強さ)に依存して空間的な倍周期分岐や3倍周期への移行、さらに、非常に乱れた相への移行が起こることを発見し、それらの相の間の転移点がコントロールパラメータの履歴に依存することが分かってきた。一方砂丘の形成のシミュレーションでは、少数の仮定による非常に単純な模型を使って、様々な形状の大規模な孤立砂丘の形成過程を大まかに再現することに成功した。これにより、砂丘の大規模で多様なパターン形成に関して、2次的な風、すなわち、砂丘の風下側での渦や乱流などの存在は、必要条件でないことが明らかになった。また、バルハンと呼ばれる砂丘について、2次的な孤立波として振る舞うことを定性的に示し、同時に一次元模型でより定量的な性質を調べた。具体的には、孤立波のスピードと高さが互いに逆比例することを明らかにした。
以上の結果は、論文として雑誌に発表されるとともに日本物理学会、および、日本地質学会、三鉱学会など複数の学会で講演発表されており、その学際的な研究内容と結果は非線形物理学と地球環境を直接つなぐ新たな学際領域構築の布石になることが期待される。 -
On the Generation of l/f Noise in Black Hole Objects
Grant number：05836017 1993 - 1994
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for General Scientific Research (C)
MINESHIGE Shin, NISHIMORI H
Grant amount：\2200000 （ Direct Cost: \2200000 ）
There exist short-term fluctuations with a frequency dependence of f^<-beta> with beta-1 in the X-rays from stellar black-hole candidates and active galactic nuclei.The amplitude (or the peak intensity) of the fluctuations shows a rather smooth distribution without any typical values, just like solar flares.The basic features of the fluctuations can be understood, if the inner portions of the disk is in a self-organized state ; when the mass density of the disk exceeds some critical value, an unknown instability is assumed to become established and accumulated material begins to drift inward as an avalanche, thereby emitting X-rays.As to the origin of the assumed instability, the reconnection of disk magnetic fields, resulting in flares similar to solar flares, is the most promising candidate. On the basis of this working hypothesis, we conjecture that a black-hole accretion disk oscillates between a solar-type (high-beta) disk with small variabilities and a coronal (low-beta) disk with large fluctuations.Magnetic fields emerge via buoyancy in the from of loo-like structures in the former, whereas the latter is composed of blobs threaded by mainly toroidal fields.
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Study of complex systems by the method of position-fixed reaction
Grant number：05836003 1993 - 1994
Japan Society for the Promotion of Science Grants-in-Aid for Scientific Research Grant-in-Aid for General Scientific Research (C)
TAINAKA Keiichi, KANNO S, NISHIMORI H
Grant amount：\2300000 （ Direct Cost: \2300000 ）
There is a fundamental problem in ecology : Can we determine the cause of extinction? Recently, Tainaka presented an uncertainty hypothesis : anyone cannot predict an extinction of biological species, nor pursue the cause of extinction.According to this theory, the uncertainty requires two conditions, that is, the indirect effect and phase transition.Under these conditions, we cannot neglect the effect of network of food web ; the survival and extinction of species becomes sensitive to the fine structure of network (uncertainty). If the uncertainty theory is true, it strongly influences on various fields in biology.For example, the uncertainty theory practically destroys the concept of natural selection.
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位置固定反応法による生態系パターン形成の研究
Grant number：05215210 1993
日本学術振興会 科学研究費助成事業 重点領域研究
泰中 啓一, 菅野 正吉, 西森 拓
Grant amount：\800000 （ Direct Cost: \800000 ）
位置固定反応法(PFR)というシミュレーション手法を主として生態系のモデルに適用した。具体的には次のような結論を得た。
1.ある不要な生物を除去しつづけてもその生物は減るとは限らない。
2.生態系におけるカタストロフィーの原因を究明することは不可能である。
たとえばバッタの個体数が突然増えたとき、生態学者は通常その生物種にとって有利な環境要因を探す。しかしそれはあまりにも短絡的すぎる。なぜならバッタとはまったく関係のない生物による環境影響が巡り巡ってバッタの増加を間接的に引き起すからである。それどころか逆にバッタにとって不利な環境要因からでもバッタの異常増加が起こる可能性があることを示した。この結果はダーウィンの単純な進化論を否定することになる。 -
非一様な固体の集合体の非線形動力学
Grant number：05740248 1993
日本学術振興会 科学研究費助成事業 奨励研究(A)
西森 拓
Grant amount：\800000 （ Direct Cost: \800000 ）
適当な外力が印加されたとき、固体の集合体(砂、地盤)は複雑な振る舞いを示す。ある条件下では、全体として、コヒーレントな運動を行う(砂丘の高速移動など)一方、別の条件下では各要素が、バラバラに振る舞うように見える(流砂現象、地盤液状化)。これらの複雑な振る舞いは、おもに系の離散性、非一様性に由来し従来の理論解析法では把握が困難であり、その規模の大きさ、および適当なスケール変換規則が未知であるゆえ、実験的な制御も難しい。
今回の研究では、最近の非線形動力学の進展の中で得られつつある、新しい知見と手法(など)を運用して、このような複雑な系の動的過程、とくに砂地形のダイナミクスを明らかにしてきた。具体的には申請者らが現在まで、改良を進めてきた連結写像格子法と呼ばれる非常に効率の良い数値模型を使って、砂のダイナミクスを再現することで、風紋や砂丘の形成機構、移動形態、を詳細に調べてきた。また線形解析、を実行し、系の複雑な時間発展が、その非一様性や、非線形性といかに連動しているのかを明らかにし、次ページに記載した論文として発表した。 -
非拡散衝突モデルによる複雑系パターン形成の研究
Grant number：04231206 1992
日本学術振興会 科学研究費助成事業 重点領域研究
泰中 啓一, 菅野 正吉, 西森 拓
Grant amount：\800000 （ Direct Cost: \800000 ）
最近、私たちは非拡散衝突モデルという新しいコンピューター・シミュレーション手法を開発した。この手法の最大の利点は、反応拡散方程式にかわって複雑系の空間パターンを容易に研究できるという点にある。昨年までは、この手法を主として生態系の空間パターン形成の問題に適用してきた。
本研究の目的は、生態系だけでなく、化学反応系、さらには社会学や宇宙物理学のさまざまな“複雑系"に対しても、非拡散衝突モデルを適用し、計算機物理の中でその地位を確立させることを目的としていた。この目的は基本的に達成された。すなわち、生態系のみならず、社会学とりわけ選挙の問題さらには宇宙物理学の分野において、これまで得られて来なかった新しい知見を得ることができた。
1.生態系では、具体的には拾食者と餌と空地の3つの状態から成る系を研究した。簡単な反応モデルによって空間パターンを自己組織的に作り出した。その結果次のような新しい知見を得た。ある生物を我々が除去し、又は殺しつづけても、その生物は減少するとは限らない。
2.選挙とマスコミの問題では次のような成果を得た。(1)ある候補者がスキャンダルの公表によってマスコミからダメージを受けても、その候補者の支持層は減少するとは限らない。(2)マスコミから無視された候補者にも大きな影響が及ぶ。(3)選挙の直前のマスコミ報道は直接的な影響を有権者に及ぼす、これらの成果については産経新聞(3月6日付)にも大きく報道された。
3.宇宙物理学の分野では、銀河内星間ガスの空間構造について考えた。銀河内星間ガスとしては、cold cloudやhot gasが非常に多く存在することができるの対して、warm gasが多く存在することができない理由を説明した。
Social Activities
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「いきもの」とうごく「モノ」 ～ 見て、比べて、測って、楽しもう～
Role(s)： Lecturer, Planner, Organizing member, Demonstrator
大阪関西万博クラゲ館 大阪関西万博クラゲ館ワークショップ 2025.9
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