YANAO, Tomohiro

写真a

Affiliation

Faculty of Science and Engineering, School of Fundamental Science and Engineering

Job title

Professor

Homepage URL

http://www.f.waseda.jp/yanao/

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Concurrent Post 【 display / non-display 】

  • Faculty of Science and Engineering   Graduate School of Fundamental Science and Engineering

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Research Institute 【 display / non-display 】

  • 2020
    -
    2022

    理工学術院総合研究所   兼任研究員

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Education 【 display / non-display 】

  • 　
    -
    2003

    University of Tokyo   Graduate School of Arts and Sciences   Multidisciplinary Science  

  • 　
    -
    2003

    University of Tokyo   Graduate School of Arts and Sciences   Multidisciplinary Science  

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Degree 【 display / non-display 】

  • University of Tokyo   Ph.D.

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Research Experience 【 display / non-display 】

  • 2011
    -
    　

    Waseda University, Associate Professor

  • 2011
    -
    　

    Waseda University, Associate Professor

  • 2009
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    Waseda University, Assistant Professor

  • 2008
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    California Institute of Technology, JSPS Fellow for Research Abroad

  • 2006
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    Fukui Institute for Fundamental Chemistry, Research Fellow

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Professional Memberships 【 display / non-display 】

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    Japan Society for Molecular Science

  • 　
    　
    　

    Physical Society of Japan

  • 　
    　
    　

    American Physical Society

  • 　
    　
    　

    Society for Industrial and Applied Mathematics

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Research Areas 【 display / non-display 】

  • Biophysics, chemical physics and soft matter physics

  • Mathematical physics and fundamental theory of condensed matter physics

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Research Interests 【 display / non-display 】

  • statistical mechanics, nonlinear dynamics, geometric mechanics, applied mathematics, molecular science, biophysics, celestial mechanics

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Papers 【 display / non-display 】

  • Geometric somersaults of helical chains through twist propagation

    Shiori Uda, Mengyun Li, Tomohiro Yanao

    Artificial Life and Robotics   23 ( 1 ) 28 - 33  2018.03

    　View Summary

    This study is concerned with the rotary motions of helical chains that play essential roles in the functions of molecular motors in biological systems. While the standard pictures for the rotary motions of molecular motors may be more or less like the rotations of rigid bodies, this study explores a qualitatively different mechanism for the rotary motions. We take a simple model of a helical chain and highlight its geometric angle shifts induced by internal twist propagation. Such angle shifts, which we call geometric somersaults, can generally arise even under the conditions of zero total angular momentum, and are thereby analogous to the somersault of a falling cat. Helical chirality of the chain and the direction of twist propagation are the decisive factors that determine the direction of the resulting somersaults. As an application, we argue that the geometric somersaults of the helical chain may serve as a prototypical model for the rotary motions of the central shaft of ATP synthase.

    DOI

  • Analysis of medium-energy transfers to the Moon

    Kenta Oshima, Francesco Topputo, Stefano Campagnola, Tomohiro Yanao

    CELESTIAL MECHANICS & DYNAMICAL ASTRONOMY   127 ( 3 ) 285 - 300  2017.03  [Refereed]

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    This study analyzes a recently discovered class of exterior transfers to the Moon. These transfers terminate in retrograde ballistic capture orbits, i.e., orbits with negative Keplerian energy and angular momentum with respect to the Moon. Yet, their Jacobi constant is relatively low, for which no forbidden regions exist, and the trajectories do not appear to mimic the dynamics of the invariant manifolds of the Lagrange points. This paper shows that these orbits shadow instead lunar collision orbits. We investigate the dynamics of singular, lunar collision orbits in the Earth-Moon planar circular restricted three-body problem, and reveal their rich phase space structure in the medium-energy regime, where invariant manifolds of the Lagrange point orbits break up. We show that lunar retrograde ballistic capture trajectories lie inside the tube structure of collision orbits. We also develop a method to compute medium-energy transfers by patching together orbits inside the collision tube and those whose apogees are located in the appropriate quadrant in the Sun-Earth system. The method yields the novel family of transfers as well as those ending in direct capture orbits, under particular energetic and geometrical conditions.

    DOI

  • Global search for low-thrust transfers to the Moon in the planar circular restricted three-body problem

    Oshima, Kenta, Campagnola, Stefano, Yanao, Tomohiro

    Celestial Mechanics and Dynamical Astronomy     1 - 20  2017.02  [Refereed]

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    © 2017 Springer Science+Business Media DordrechtThis paper globally searches for low-thrust transfers to the Moon in the planar, circular, restricted, three-body problem. Propellant-mass optimal trajectories are computed with an indirect method, which implements the necessary conditions of optimality based on the Pontryagin principle. We present techniques to reduce the dimension of the set over which the required initial costates are searched. We obtain a wide range of Pareto solutions in terms of time of flight and mass consumption. Using the Tisserand–Poincaré graph, a number of solutions are shown to exploit high-altitude lunar flybys to reduce fuel consumption.

    DOI

  • Geometric somersaults of a polymer chain through cyclic twisting motions

    Yanao, Tomohiro, Hino, Taiko

    Physical Review E - Statistical, Nonlinear, and Soft Matter Physics   95 ( 1 )  2017.01

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    © 2017 American Physical Society.This study explores the significance of geometric angle shifts, which we call geometric somersaults, arising from cyclic twisting motions of a polymer chain. A five-bead polymer chain serves as a concise and minimal model of a molecular shaft throughout this study. We first show that this polymer chain can change its orientation about its longitudinal axis largely, e.g., 120, under conditions of zero total angular momentum by changing the two dihedral angles in a cyclic manner. This phenomenon is an example of the so-called "falling cat" phenomenon, where a falling cat undergoes a geometric somersault by changing its body shape under conditions of zero total angular momentum. We then extend the geometric somersault of the polymer chain to a noisy and viscous environment, where the polymer chain is steered by external driving forces. This extension shows that the polymer chain can achieve an orientation change keeping its total angular momentum and total external torque fluctuating around zero in a noisy and viscous environment. As an application, we argue that the geometric somersault of the polymer chain by 120 may serve as a prototypical and coarse-grained model for the rotary motion of the central shaft of ATP synthase (FOF1-ATPase). This geometric somersault is in clear contrast to the standard picture for the rotary motion of the central shaft as a rigid body, which generally incurs nonzero total angular momentum and nonzero total external torque. The power profile of the geometric somersault implies a preliminary mechanism for elastic power transmission. The results of this study may be of fundamental interest in twisting and rotary motions of biomolecules.

    DOI

  • Jumping mechanisms of Trojan asteroids in the planar restricted three- and four-body problems

    Kenta Oshima, Tomohiro Yanao

    CELESTIAL MECHANICS & DYNAMICAL ASTRONOMY   122 ( 1 ) 53 - 74  2015.05  [Refereed]

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    We explore minimal dynamical mechanisms for the transport of Trojan asteroids between the vicinities of the stable Lagrange points and within the framework of the planar restricted three- and four-body problems. This transport, called "jumping" of Trojan asteroids, has been observed numerically in the sophisticated Solar System models. However its dynamical mechanisms have not been fully explored yet. The present study shows that invariant manifolds emanating from an unstable periodic orbit around the unstable Lagrange point mediate the jumping of Trojan asteroids in the Sun-Jupiter planar restricted three-body problem. These invariant manifolds form homoclinic tangles and lobes when projected onto the configuration space through a discrete mapping. Thus the resulted lobe dynamics explains the mechanism for the jumping of Jupiter's Trojan asteroids. In the Sun-Earth planar restricted three-body problem, on the other hand, invariant manifolds of an unstable periodic orbit around do not exhibit clear homoclinic tangles nor lobes, indicating that the jumping is very difficult to occur. It is then shown that the effect of perturbation of Venus is important for the onset of the jumping of Earth's Trojan asteroids within the framework of the Sun-Earth-Venus planar restricted four-body problem. The results presented here could shed new insights into the transport mechanism as well as trajectory design associated with L-3, L-4 and L-5.

    DOI

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Research Projects 【 display / non-display 】

  • 複雑な流体現象のモデリング，マルチスケール構造の解明と数理解析

    Project Year :

    2016.07
    -
    2019.03
     

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    キャビテーション，衝撃波の伝播，多成分流体，大気の循環などの流体解析では，ミクロとマクロの境界で発生するマルチスケール現象や非平衡系の数学的解析が重要である．本研究では，複雑流体のモデリング，マルチスケール構造の解明と数学解析手法の確立を目的とする．2016年度は，モデリング，数学解析と応用に分けて研究を推進した．流体のモデリングについては，有限自由度の離散的な非平衡熱力学系についての変分的な定式化を行った．また，キャビテーション気泡と気泡クラウドに関する実験，レイリー・ベナール対流の解析を中心に行った．数学解析としては，ナビエ・ストークス方程式，オイラー方程式，非線型シュレディンガー方程式をはじめとする非線型発展方程式の初期値問題の時間大域解の存在を保障する先験評価に重要な役割を果たす対数型ソボレフ埋蔵に就いて研究し，放物型方程式に対してはその散逸構造に因り通常のソボレフ埋蔵の枠組で閉じている事を明らかにした．また，非圧縮粘性流体の自由境界問題を有界領域の場合に考察し、時間局所解の一意存在と時間大域解の一意存在及び解の漸近挙動を示した．さらに，複数の保存量を持つ微視的な系から非線形流体力学揺動理論を経て導かれると予想される，多成分 KPZ 方程式について考察し，殆ど全ての初期値に対し方程式は大域的適切性を持つことを示した．また，質量保存アレン-カーン方程式にノイズを加えて得られる確率偏微分方程式について，極限で確率的摂動を持つ質量保存平均曲率運動が導かれることを示した．数値解析として，準離散化方程式の対称性と保存則を研究し，ネーター定理を導き，高階の場の理論のために，マルチシンプレクティック構造の研究を行った．非線形力学の応用として，ミクロスケールでの高分子鎖の捩れ運動から生じる幾何学的位相を見出し，回転型分子モーターの回転軸運動の粗視化モデルに適用した．概ね順調に進んでいるが，研究代表者と分担者４名で研究内容が多岐に渡るため，全体のまとまりを考えて，本来の研究目的に沿って組織的に研究を遂行する必要があると考えている．複雑流体のモデリングについては，連続的な非平衡系としての変分的定式化の確立，レリー・ベナール対流の解析，気泡クラウドのマクロモデルの構築，確率的な気泡ダイナミクスの変分的定式化と解析を中心に進める．数学解析では，部分積分に依る時間発散型の高次繰り操みエネルギーとブレジス・ガルエの論法を駆使し，半相対論的方程式の高次相互作用が数学的に実現されるかどうか，検討する．また，２相流問題の考察を行い，まずは非圧縮・非圧縮の２相問題についての有界領域で外側の境界条件が自由境界条件の場合を考える．つづいて，一方が有界領域、外側がその補集合である全空間での２相問題を考え，この時間局所解，時間大域解、解の漸近挙動を示す．さらに，多成分KPZ方程式について，カップリング定数が3重線形性を満たさない場合の不変測度の研究，大規模相互作用系からのKPZ方程式の導出を目指した研究，ノイズ項が空間変数にも依存する確率アレン-カーン方程式や確率的平均曲率運動に関する研究などを進める．数値解析については，マルチシンプレクティック構造の研究を続け，流体力学への応用，特に拘束を含む系への応用を考え，離散的ディラック構造の研究も進行する予定である．非線形力学の応用として，高分子鎖の捩れ運動から生じる幾何学的位相の効果を，ベン毛微生物の遊泳機構の解明に応用する．できるだけ，分担者からの使用ができるだけ均一になるように早めの確認と連絡をしたい．また，大学院生による研究調査や協力のための謝金にも利用したい

  • Study on the mechanisms for collective motions of molecular and astronomical systems based the methods of many-body problems

    Project Year :

    2014.04
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    2017.03
     

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    Understanding the fundamental mechanisms for collective motions of many-body systems, ranging from the microscopic molecular systems to macroscopic astronomical systems, is a significant challenge in modern science and technology. In this study, we have tackled this issue utilizing the methodologies of nonlinear dynamics, statistical mechanics, and differential geometry. As a result, we have developed novel dynamical models for the rotary motions of biological molecular motors and the formation of higher-order structures of DNA. We have also uncovered a dynamical mechanism for driving the dissociation of atomic clusters in terms of the competition between collective internal forces. As to the macroscopic astronomical systems, we have designed fuel-efficient transfer trajectories for space missions between the Earth and the Moon by using resonant gravity assists and invariant manifolds of periodic orbits

  • Study on collective motions and functions of complex molecular systems based on the geometry of shape and rotational dynamics

    Project Year :

    2011.04
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    2014.03
     

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    In this project, we have investigated the mechanisms for collective motions, reactions, and functions of complex molecular systems on the basis of statistical mechanics, nonlinear dynamics, and geometry. We have clarified the driving mechanisms for oblate-prolate structural transitions and dissociations of atomic clusters. We have also clarified asymmetric elasticity of biomolecules such as DNA and its significance in the formation of higher-order structures. Moreover, we have studied the mechanisms for the transport of asteroids between local equilibria based on the dynamical analogy between molecular systems and planetary systems

  • Elucidation of the mechanisms for collective motions of complex molecular systems with hierarchical structures

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    This study focused on the mechanisms for large-amplitude collective motions of complex molecular systems with highly-organized hierarchical structures and functions. We found that specific mode coupling and energy transfer among internal (vibrational) modes govern the onset and rates of structural transitions of atomic/molecular clusters. We also scrutinized elastic properties of DNA and clarified the mechanisms for the spontaneous selection of chirality of higher-order structures of DNA

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Presentations 【 display / non-display 】

  • Mode-specific effects in structural transitions of atomic clusters with multiple channels

    SIAM Conference on Applications of Dynamical Systems 

    Presentation date： 2015.05

  • Collective motions of complex molecular systems driven by spontaneous symmetry breaking

    Workshop on Energy Landscapes 

    Presentation date： 2014.08

  • Chaotic state transitions in molecular and astronomical systems

    Workshop on Lagrangian Coherent Structures and Dynamical Systems 

    Presentation date： 2014.03

  • Geometric effects in shape dynamics of complex molecular systems

    International Symposium on Computational Materials and Biological Sciences 

    Presentation date： 2013.09

  • Intramolecular Energy Flow and the Mechanisms for Collective Motions of Complex Molecular Systems

    International Conference on Flow Dynamics 

    Presentation date： 2012.09

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Specific Research 【 display / non-display 】

  • 自然界における捩れ・渦・回転の協同運動の解明と予測

    2018  

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    本研究では，ミクロからマクロまで，自然の各階層で生じる捩れ，渦，回転の協同現象を，非線形力学，統計力学，幾何学の観点から理論的に解明し，予測することを目的とした．特に，らせん構造を基本モチーフとする生体高分子の「回転」機構の新たなモデルの構築を目指して，らせん型フィラメントの上を捩れの波動が伝播することによって生じる幾何学的な角度変位の機構を明らかにした．また，分子系および天体系の基本モデルとして重要な３体問題に着目し，３体系の周期的な変形運動から生じる幾何学的な角度変位を，慣性主軸のキネマティクスの観点から定量化した．また，時間遅れ座標の手法を用いて，原子集合体の協同的かつ突発的な構造変化の前兆を捉え，この前兆が原子集合体の捩れ運動から生じる構造変化の駆動力の振る舞いと対応していることを明らかにした．

  • 多体系の非線形ダイナミクスから生じる集団運動の理解と応用

    2009  

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    本研究の目的は、非線形力学および幾何学の手法を応用することで、原子・分子集合体のミクロスケールな運動から、天体・宇宙探査機のようなマクロスケールの運動までを「多体系の集団運動」という普遍的な観点から理解し、工学的に応用することにある。特に、ミクロとマクロ、および速い運動と遅い運動というスケール間の相互作用に注目し、多重スケールを有する複雑システムの集団運動の統一的な理解と制御を目指してきた。　本年度はまず、原子・分子スケールの興味深い現象として、オゾン分子の解離反応、アルゴンクラスターの構造異性化運動、水クラスターの構造変化運動を取りあげた。これらの現象は、どれも分子内の多くの自由度が協同的に関与することによって発生する集団運動である。このような集団運動の動的な機構を明らかにするために、我々は、近年開発した超球モード解析という多体系の振動回転運動の解析法を上述の系に応用した。その結果、上述の系において集団運動が発生する際には，系の内部モード間で特定のエネルギーの受け渡しが生じることが明らかになった。さらに、これらのエネルギーの受け渡しのパターンを解析することで、集団運動に直接的に関与する集団モードと、集団モードにエネルギーを注入する役割を果たす駆動モードが存在することが分かった。現在は、これらの集団モードと駆動モードを用いることで原子分子系の集団運動をコントロールする方法論を開発中である。また、この方法論を宇宙探査機の軌道計算へと応用する研究も開始している。　本研究ではまた、ナノメートルからマイクロメートルのスケールに渡る興味深い階層性システムとして真核生物のDNAを取り上げ、その折り畳みの機構の一端を探る研究を行った。まず右巻き２重らせん構造をもつDNAを弾性体のネットワークとしてモデル化し、その基本的な弾性特性を探った。その結果、DNAの曲げと捩れのカップリングの機構が明らかになり、DNAが折り畳み構造をとる際に右巻きと左巻きの間のカイラル対称性が破れる仕組みを明らかにした。

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Syllabus 【 display / non-display 】

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