Language：English  

DOI： 10.1039/9781788013499-00284

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.7566/JPSJ.87.044803

Other Link： https://journals.jps.jp/doi/10.7566/JPSJ.87.044803

Language：English   Publishing type：Research paper (scientific journal)  

In most practical situations, active particles are affected by their environment, for example, by a chemical concentration gradient, light intensity, gravity, or confinement. In particular, the effect of an external flow field is important for particles swimming in a solvent fluid. For deformable active particles such as self-propelled liquid droplets and active vesicles, as well as microorganisms such as euglenas and neutrophils, a general description has been developed by focusing on shape deformation. In this review, we present our recent studies concerning the dynamics of a single active deformable particle under an external flow field. First, a set of model equations of active deformable particles including the effect of a general external flow is introduced. Then, the dynamics under two specific flow profiles is discussed: a linear shear flow, as the simplest example, and a swirl flow. In the latter case, the scattering dynamics of the active deformable particles by the swirl flow is also considered.

DOI： 10.7566/JPSJ.86.101011

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1103/PhysRevE.96.022602

Other Link： https://journals.aps.org/pre/abstract/10.1103/PhysRevE.96.022602

Language：English   Publishing type：Research paper (scientific journal)  

Dynamics of active deformable particles in an external Poiseuille flow is investigated. To make the analysis general, we employ time-evolution equations derived from symmetry considerations that take into account an elliptical shape deformation. First, we clarify the relation of our model to that of rigid active particles. Then, we study the dynamical modes that active deformable particles exhibit by changing the strength of the external flow. We emphasize the difference between the active particles that tend to self-propel parallel to the elliptical shape deformation and those self-propelling perpendicularly. In particular, a swinging motion around the centerline far from the channel walls is discussed in detail.

DOI： 10.1103/PhysRevE.96.022602

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.7566/JPSJ.86.101011

Other Link： https://journals.jps.jp/doi/10.7566/JPSJ.86.101011

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1209/0295-5075/114/30002

Other Link： https://iopscience.iop.org/article/10.1209/0295-5075/114/30002

Language：English   Publishing type：Research paper (scientific journal)  

Reciprocating motion of an active deformable particle in a homogeneous medium is studied theoretically. For generality, we employ a simple model derived from symmetry considerations for the center-of-mass velocity and elliptical and triangular deformations in two dimensions. We carry out, for the first time, a systematic investigation of the reciprocating motion of a self-propelled particle. It is clarified that spontaneous breaking of the front-rear asymmetry is essential for the reciprocating motion. Moreover, two routes are found for the formation of the reciprocating motion. One is a bifurcation from a motionless stationary state. The other is destabilisation of an oscillatory rectilinear motion. Copyright (C) EPLA, 2016

DOI： 10.1209/0295-5075/114/30002

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1016/j.physd.2015.10.007

Other Link： https://www.sciencedirect.com/science/article/abs/pii/S0167278915001967?via%3Dihub

Language：English   Publishing type：Research paper (scientific journal)  

Based on symmetry consideration of migration and shape deformations, we formulate phenomenologically the dynamics of cell crawling in two dimensions. Forces are introduced to change the cell shape. The shape deformations induce migration of the cell on a substrate. For time-independent forces we show that not only a stationary motion but also a limit cycle oscillation of the migration, velocity and the shape occurs as a result of nonlinear coupling between different deformation modes. Time-dependent forces are generated in a stochastic manner by utilizing the so-called coherence resonance of an excitable system. The present coarse-grained model has a flexibility that it can be applied, e.g., both to keratocyte cells and to Dictyostelium cells, which exhibit quite different dynamics from each other. The key factors for the motile behavior inherent in each cell type are identified in our model. (C) 2015 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.physd.2015.10.007

Language：English  

DOI： 10.1093/ptep/ptv029

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1103/PhysRevE.90.042311

Other Link： https://journals.aps.org/pre/abstract/10.1103/PhysRevE.90.042311

Language：English   Publishing type：Research paper (scientific journal)  

Ferrogels and magnetic elastomers feature mechanical properties that can be reversibly tuned from outside through magnetic fields. Here we concentrate on the question of how their dynamic response can be adjusted. The influence of three factors on the dynamic behavior is demonstrated using appropriate minimal models: first, the orientational memory imprinted into one class of the materials during their synthesis; second, the structural arrangement of the magnetic particles in the materials; and third, the strength of an external magnetic field. To illustrate the latter point, structural data are extracted from a real experimental sample and analyzed. Understanding how internal structural properties and external influences impact the dominant dynamical properties helps to design materials that optimize the requested behavior.

DOI： 10.1103/PhysRevE.90.042311

Language：English   Publishing type：Research paper (scientific journal)  

Inspired by the classical Kepler and Rutherford problem, we investigate an analogous setup in the context of active microswimmers: the behavior of a deformable microswimmer in a swirl flow. First, we identify new steady bound states in the swirl flow and analyze their stability. Second, we study the dynamics of a self-propelled swimmer heading towards the vortex center, and we observe the subsequent capturing and scattering dynamics. We distinguish between two major types of swimmers, those that tend to elongate perpendicularly to the propulsion direction and those that pursue a parallel elongation. While the first ones can get caught by the swirl, the second ones were always observed to be scattered, which proposes a promising escape strategy. This offers a route to design artificial microswimmers that show the desired behavior in complicated flow fields. It should be straightforward to verify our results in a corresponding quasi-two-dimensional experiment using self-propelled droplets on water surfaces.

DOI： 10.1103/PhysRevE.90.032907

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1103/PhysRevE.90.032907

Other Link： https://journals.aps.org/pre/abstract/10.1103/PhysRevE.90.032907

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1140/epjst/e2014-02088-y

Other Link： https://link.springer.com/article/10.1140/epjst/e2014-02088-y

Language：English   Publishing type：Research paper (scientific journal)  

Deformable self-propelled particles provide us with one of the most important nonlinear dissipative systems, which are related, for example, to the motion of microorganisms. It is emphasized that this is a subject of localized objects in non-equilibrium open systems. We introduce a coupled set of ordinary differential equations to study various dynamics of individual soft particles due to the nonlinear couplings between migration, spinning and deformation. By introducing interactions among the particles, the collective dynamics and its collapse are also investigated by changing the particle density and the interaction strength. We stress that assemblies of self-propelled particles also exhibit a variety of non-equilibrium localized patterns. It is our great pleasure to dedicate the present article to Professor Helmut R. Brand on the occasion of his sixtieth birthday. Professor Brand has made outstanding efforts for the scientific interaction in the field of non-linear and non-equilibrium physics between Japan and Germany for the past thirty years.

DOI： 10.1140/epjst/e2014-02088-y

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1063/1.4820416

Other Link： https://aip.scitation.org/doi/10.1063/1.4820416

Language：English   Publishing type：Research paper (scientific journal)  

The motion of a deformable active particle in linear shear flow is explored theoretically. Based on symmetry considerations, we propose coupled nonlinear dynamical equations for the particle position, velocity, deformation, and rotation. In our model, both, passive rotations induced by the shear flow as well as active spinning motions, are taken into account. Our equations reduce to known models in the two limits of vanishing shear flow and vanishing particle deformability. For varied shear rate and particle propulsion speed, we solve the equations numerically in two spatial dimensions and obtain a manifold of different dynamical modes including active straight motion, periodic motions, motions on undulated cycloids, winding motions, as well as quasi-periodic and chaotic motions induced at high shear rates. The types of motion are distinguished by different characteristics in the real-space trajectories and in the dynamical behavior of the particle orientation and its deformation. Our predictions can be verified in experiments on self-propelled droplets exposed to a linear shear flow. (C) 2013 AIP Publishing LLC.

DOI： 10.1063/1.4820416

Language：English   Publishing type：Research paper (scientific journal)  

We investigate dynamics of an active particle in which shape deformations occur spontaneously. In two dimensions, the deformations are expanded in terms of the Fourier series and the couplings of different modes are taken into consideration truncated up to lower orders. We focus our attention on the special symmetrical structure between the coupled equations of n- and 2n-mode deformations for n=1, and those for n=2. We show that an oscillatory bifurcation occurs for n=2, which corresponds mathematically to the bifurcation for n=1 where a straight motion becomes unstable and a circular motion appears. At the oscillatory state, the particle undergoes either a spinning motion or a standing oscillation of shape deformations. © 2013 American Physical Society.

DOI： 10.1103/PhysRevE.87.062912

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1103/PhysRevE.87.062912

Other Link： https://journals.aps.org/pre/abstract/10.1103/PhysRevE.87.062912

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1093/ptep/pts051

Other Link： https://academic.oup.com/ptep/article/2013/1/013A01/1563466

Language：English   Publishing type：Research paper (scientific journal)  

We investigate the dynamics of a single deformable active particle that is accompanied by two types of internal force. One is related to the spontaneous propulsion of the center of mass and the other to the spontaneous spinning motion around the center of mass. The equations of motion are derived from the symmetry argument for the velocity of the center of mass, the traceless symmetric tensor variable characterizing the deformation, and the antisymmetric tensor variable for the spinning motion. Numerical simulations are carried out in both two and three dimensions to investigate the dynamics due to the coupling between migration, deformation, and spinning. Some of the bifurcations are studied by an analytical approach.

DOI： 10.1093/ptep/pts051

Language：English   Publishing type：Research paper (scientific journal)  

We investigate the dynamics of a single deformable self-propelled particle which undergoes a spinning motion in a two-dimensional space. Equations of motion are derived from symmetry arguments for three kinds of variable. One is a vector which represents the velocity of the center of mass. The second is a traceless symmetric tensor representing deformation. The third is an antisymmetric tensor for spinning degree of freedom. By numerical simulations, we have obtained a variety of dynamical states due to interplay between the spinning motion and the deformation. The bifurcations of these dynamical states are analyzed by the simplified equations of motion.

DOI： 10.1088/0953-8984/24/46/464129

Language：English   Publishing type：Research paper (scientific journal)  

DOI： https://doi.org/10.1088/0953-8984/24/46/464129

Other Link： https://iopscience.iop.org/article/10.1088/0953-8984/24/46/464129

Language：English   Publishing type：Research paper (scientific journal)  

We investigate dynamics of a deformable self-propelled particle under external fields in two dimensions based on the time-evolution equations for the center of mass and a tensor variable characterizing deformations. We consider two kinds of external force. One is a gravitational force which enters additively in the time-evolution equation for the center of mass. The other is an electric force supposing that a dipole moment is induced in the particle. This force is added to the equation for the deformation tensor. It is shown that a rich variety of dynamics appears by changing the strength of the forces and the migration velocity of a self-propelled particle. A theoretical analysis is carried out to clarify the dynamics and the bifurcations.

DOI： 10.1140/epjb/e2011-20307-7

Language：English   Publishing type：Research paper (scientific journal)  

We investigate the stability of an excited domain in a two-component reaction-diffusion system in two dimensions and correct the previous results obtained by one of the authors [L. M. Pismen, Patterns and Interfaces in Dissipative Dynamics (Springer, Berlin, 2006); Phys. Rev. Lett. 86, 548 (2001)].

DOI： 10.1103/PhysRevE.83.017201

Event date： 2022.10

Language：English   Presentation type：Oral presentation (general)  

Venue：Yukawa Institute for Theoretical Physics, Kyoto University   Country：Japan  

Other Link： https://www2.yukawa.kyoto-u.ac.jp/~german-japan2022/index.php

Event date： 2022.9

Language：Japanese   Presentation type：Oral presentation (general)  

Country：Japan  

Event date： 2022.9

Language：Japanese  

Country：Japan  

Event date： 2021.9

Language：Japanese  

Country：Other  

Epigenetic maintenance controlled by the size of competitive pronuclei in zygotes

Event date： 2021.9

Language：Japanese  

Country：Other  

Cortical structure formation and force generation of actin filaments driven by motor activity

Event date： 2021.9

Language：Japanese  

Country：Other  

Dynamic meshwork structure formation of mesoderm cells in early chick embryo

Event date： 2021.7

Language：English  

Country：Other  

Event date： 2021.1

Language：English  

Country：Other  

Cortex structure formation of actomyosin by motor activity

Event date： 2020.9

Language：English  

Country：Other  

Formation of actin cortex structure by myosin motor activity

Event date： 2019.8

Language：Japanese  

Country：Other  

Modeling dynamics around cells

Event date： 2019.1

Language：English  

Country：Other  

Language：Japanese  

Country：Other  

アクティブマターの往復運動への分岐

Language：English  

Country：Other  

Language：English  

Country：Other  

Reciprocating motion of active deformable particles in homogeneous media

Language：English  

Country：Other  

Back-and-forth motion of active soft particle

Language：English  

Country：Other  

Reciprocating motion of active deformable particles

Language：English  

Country：Other  

Back-and-forth motion of active deformable particles

Language：Japanese  

Country：Other  

ポアズイユ流中での変形するアクティブマターのダイナミクス
<p>周囲の環境からの外力を受けつつ運動するアクティブマターは興味深い研究対象であり、盛んに研究されている。中でも、流体中を泳動するアクティブマターのダイナミクスを理解する上で周囲の流れ場の影響は無視できない。これまで発表者は流れ場中のアクティブマターのダイナミクスを記述する一般的なモデルを構築した。本発表では、ポアズイユ流れ中での変形するアクティブマターのダイナミクスに関する研究についてお話しする。</p>

Language：English  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Active Deformable Particles in Poiseuille Flow

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Dynamics of active deformable particles: from swimming droplets to crawling cells

Language：English  

Country：Other  

Language：English  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

基盤上を這行する細胞運動の力学メカニズム

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Mechanics of cell crawling by means of force-free cyclic motion

Language：English  

Country：Other  

Swinging motion of active deformable particles in Poiseuille flow

Language：English  

Country：Other  

Mechanics of cell crawling by means of force-free cyclic motion

Language：English  

Country：Other  

Mechanics of cell crawling under force-free condition

Language：English  

Country：Other  

Dynamics of active deformable particles in Poiseuille flow

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Breathing instability versus drift instability in a two-component reaction-diffusion system

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Dynamics of a deformable self-propelled particle under external forcing

Language：Japanese  

Country：Japan  

23pGU-10 Dynamics of a deformable self-propelled particle under external forcing

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

変形を伴う自己推進粒子の外力下でのダイナミクス

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Influence of external forcing on the dynamics of a deformable self-propelled particle

Language：English  

Country：Other  

Spinning motion of a deformable self-propelled particle in a two-dimensional space

Language：English  

Country：Other  

Dynamics of a deformable particle driven by internal and external forces

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Spinning motion of an active soft particle

Language：English  

Country：Other  

Active spinning of a deformable self-propelled particle

Language：English  

Country：Other  

Spontaneous rotation of a deformable self-propelled particle

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Spontaneous spinning motion of an active deformable particle

Language：English  

Country：Other  

Dynamics of an active soft particle with spinning motion

Language：English  

Country：Other  

An active soft particle with a spontaneous spinning motion

Language：Japanese  

Country：Japan  

27aXM-4 Spinning motion of a deformable self-propelled particle

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

やわらかな自己推進粒子の自転運動

Language：English  

Country：Other  

Oscillatory motions of an active deformable particle

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Japan  

30pAJ-6 Modeling of deformable active particle in flow field and dynamics in linear shear flow

Language：Japanese  

Country：Other  

流れの中のアクティブソフトマターのモデリングと線形剪断流中でのダイナミクス

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Two types of active spinning motion of deformable particle

Language：English  

Country：Other  

Scattering dynamics of active soft particle in swirl

Language：English  

Country：Other  

Capturing and scattering dynamics of active soft particle in a swirl

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Nonlinear dynamics of active deformable particles

Language：English  

Country：Other  

Dynamics of active deformable particle in external flow field

Language：English  

Country：Other  

Active deformable particle in an external flow field

Language：Japanese  

Country：Other  

Language：Japanese  

Country：Other  

アクティブソフトマターの往復運動

Language：English  

Country：Other  

Tunable dynamic response of magnetic gels: Impact of structural properties and magnetic fields

Language：English  

Country：Other  

Oscillatory motion of active deformable particles

Language：English  

Country：Other  

Oscillation of active deformable particles

Language：English  

Country：Other  

Reciprocating motion of active deformable particles

Language：English  

Country：Other  

Language：Japanese  

Country：Other  

Language：English  

Country：Other  

Oscillatory dynamics of active deformable particles

Language：English  

Language：Japanese  

Type：Academic society, research group, etc. 

researchmap

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

researchmap

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc. 

Type：Competition, symposium, etc.