51
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Auschra S, Holubec V. Density and polarization of active Brownian particles in curved activity landscapes. Phys Rev E 2021; 103:062604. [PMID: 34271717 DOI: 10.1103/physreve.103.062604] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 04/12/2021] [Indexed: 11/07/2022]
Abstract
Suspensions of motile active particles with space-dependent activity form characteristic polarization and density patterns. Recent single-particle studies for planar activity landscapes identified several quantities associated with emergent density-polarization patterns that are solely determined by bulk variables. Naive thermodynamic intuition suggests that these results might hold for arbitrary activity landscapes mediating bulk regions, and thus could be used as benchmarks for simulations and theories. However, the considered system operates in a nonequilibrium steady state and we prove by construction that the quantities in question lose their simple form for curved activity landscapes. Specifically, we provide a detailed analytical study of polarization and density profiles induced by radially symmetric activity steps, and of the total polarization for the case of a general radially symmetric activity landscape. While the qualitative picture is similar to the planar case, all the investigated variables depend not only on bulk variables but also comprise geometry-induced contributions. We verified that all our analytical results agree with exact numerical calculations.
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Affiliation(s)
- Sven Auschra
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Viktor Holubec
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany.,Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, CZ-180 00 Praha, Czech Republic
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52
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Mori F, Le Doussal P, Majumdar SN, Schehr G. Condensation transition in the late-time position of a run-and-tumble particle. Phys Rev E 2021; 103:062134. [PMID: 34271704 DOI: 10.1103/physreve.103.062134] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Accepted: 05/25/2021] [Indexed: 11/07/2022]
Abstract
We study the position distribution P(R[over ⃗],N) of a run-and-tumble particle (RTP) in arbitrary dimension d, after N runs. We assume that the constant speed v>0 of the particle during each running phase is independently drawn from a probability distribution W(v) and that the direction of the particle is chosen isotropically after each tumbling. The position distribution is clearly isotropic, P(R[over ⃗],N)→P(R,N) where R=|R[over ⃗]|. We show that, under certain conditions on d and W(v) and for large N, a condensation transition occurs at some critical value of R=R_{c}∼O(N) located in the large-deviation regime of P(R,N). For R<R_{c} (subcritical fluid phase), all runs are roughly of the same size in a typical trajectory. In contrast, an RTP trajectory with R>R_{c} is typically dominated by a "condensate," i.e., a large single run that subsumes a finite fraction of the total displacement (supercritical condensed phase). Focusing on the family of speed distributions W(v)=α(1-v/v_{0})^{α-1}/v_{0}, parametrized by α>0, we show that, for large N, P(R,N)∼exp[-Nψ_{d,α}(R/N)], and we compute exactly the rate function ψ_{d,α}(z) for any d and α. We show that the transition manifests itself as a singularity of this rate function at R=R_{c} and that its order depends continuously on d and α. We also compute the distribution of the condensate size for R>R_{c}. Finally, we study the model when the total duration T of the RTP, instead of the total number of runs, is fixed. Our analytical predictions are confirmed by numerical simulations, performed using a constrained Markov chain Monte Carlo technique, with precision ∼10^{-100}.
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Affiliation(s)
- Francesco Mori
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Pierre Le Doussal
- Laboratoire de Physique de l'Ecole Normale Supérieure, PSL University, CNRS, Sorbonne Universités, 24 rue Lhomond, 75231 Paris, France
| | - Satya N Majumdar
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Grégory Schehr
- Sorbonne Université, Laboratoire de Physique Théorique et Hautes Energies, CNRS, UMR 7589, 4 Place Jussieu, 75252 Paris Cedex 05, France
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53
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Lauersdorf N, Kolb T, Moradi M, Nazockdast E, Klotsa D. Phase behavior and surface tension of soft active Brownian particles. SOFT MATTER 2021; 17:6337-6351. [PMID: 34128024 DOI: 10.1039/d1sm00350j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We study quasi two-dimensional, monodisperse systems of active Brownian particles (ABPs) for a range of activities, stiffnesses, and densities. We develop a microscopic, analytical method for predicting the dense phase structure formed after motility-induced phase separation (MIPS) has occurred, including the dense cluster's area fraction, interparticle pressure, and radius. Our predictions are in good agreement with our Brownian dynamics simulations. We, then, derive a continuum model to investigate the relationship between the predicted interparticle pressure, the swim pressure, and the macroscopic pressure in the momentum equation. We find that formulating the point-wise macroscopic pressure as the interparticle pressure and modeling the particle activity through a spatially variant body force - as opposed to a volume-averaged swim pressure - results in consistent predictions of pressure in both the continuum model and the microscopic theory. This formulation of pressure also results in nearly zero surface tension for the phase separated domains, irrespective of activity, stiffness, and area fraction. Furthermore, using Brownian dynamics simulations and our continuum model, we showed that both the interface width and surface tension, are intrinsic characteristics of the system. On the other hand, if we were to exclude the body force induced by activity, we find that the resulting surface tension values are linearly dependent on the size of the simulation, in contrast to the statistical mechanical definition of surface tension.
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Affiliation(s)
- Nicholas Lauersdorf
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
| | - Thomas Kolb
- Department of Chemistry, University of North Carolina at Chapel Hill, USA
| | - Moslem Moradi
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
| | - Ehssan Nazockdast
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
| | - Daphne Klotsa
- Department of Applied Physical Sciences, University of North Carolina at Chapel Hill, USA.
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54
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Auschra S, Bregulla A, Kroy K, Cichos F. Thermotaxis of Janus particles. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:90. [PMID: 34218345 PMCID: PMC8254728 DOI: 10.1140/epje/s10189-021-00090-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 06/07/2021] [Indexed: 05/26/2023]
Abstract
The interactions of autonomous microswimmers play an important role for the formation of collective states of motile active matter. We study them in detail for the common microswimmer-design of two-faced Janus spheres with hemispheres made from different materials. Their chemical and physical surface properties may be tailored to fine-tune their mutual attractive, repulsive or aligning behavior. To investigate these effects systematically, we monitor the dynamics of a single gold-capped Janus particle in the external temperature field created by an optically heated metal nanoparticle. We quantify the orientation-dependent repulsion and alignment of the Janus particle and explain it in terms of a simple theoretical model for the induced thermoosmotic surface fluxes. The model reveals that the particle's angular velocity is solely determined by the temperature profile on the equator between the Janus particle's hemispheres and their phoretic mobility contrast. The distortion of the external temperature field by their heterogeneous heat conductivity is moreover shown to break the apparent symmetry of the problem.
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Affiliation(s)
- Sven Auschra
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Andreas Bregulla
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
| | - Klaus Kroy
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
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55
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Söker NA, Auschra S, Holubec V, Kroy K, Cichos F. How Activity Landscapes Polarize Microswimmers without Alignment Forces. PHYSICAL REVIEW LETTERS 2021; 126:228001. [PMID: 34152174 DOI: 10.1103/physrevlett.126.228001] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/20/2021] [Indexed: 06/13/2023]
Abstract
Active-particle suspensions exhibit distinct polarization-density patterns in activity landscapes, even without anisotropic particle interactions. Such polarization without alignment forces is at work in motility-induced phase separation and betrays intrinsic microscopic activity to mesoscale observers. Using stable long-term confinement of a single thermophoretic microswimmer in a dedicated force-free particle trap, we examine the polarized interfacial layer at a motility step and confirm that it does not exert pressure onto the bulk. Our observations are quantitatively explained by an analytical theory that can also guide the analysis of more complex geometries and many-body effects.
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Affiliation(s)
- Nicola Andreas Söker
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
| | - Sven Auschra
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Viktor Holubec
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
- Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Prague, Czech Republic
| | - Klaus Kroy
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
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56
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Auschra S, Holubec V, Söker NA, Cichos F, Kroy K. Polarization-density patterns of active particles in motility gradients. Phys Rev E 2021; 103:062601. [PMID: 34271745 DOI: 10.1103/physreve.103.062601] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 04/21/2021] [Indexed: 11/07/2022]
Abstract
The colocalization of density modulations and particle polarization is a characteristic emergent feature of motile active matter in activity gradients. We employ the active-Brownian-particle model to derive precise analytical expressions for the density and polarization profiles of a single Janus-type swimmer in the vicinity of an abrupt activity step. Our analysis allows for an optional (but not necessary) orientation-dependent propulsion speed, as often employed in force-free particle steering. The results agree well with measurement data for a thermophoretic microswimmer presented in the companion paper [Söker et al., Phys. Rev. Lett. 126, 228001 (2021)10.1103/PhysRevLett.126.228001], and they can serve as a template for more complex applications, e.g., to motility-induced phase separation or studies of physical boundaries. The essential physics behind our formal results is robustly captured and elucidated by a schematic two-species "run-and-tumble" model.
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Affiliation(s)
- Sven Auschra
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
| | - Viktor Holubec
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany.,Charles University, Faculty of Mathematics and Physics, V Holešovičkách 2, CZ-180 00 Prague, Czech Republic
| | - Nicola Andreas Söker
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
| | - Frank Cichos
- Peter Debye Institute for Soft Matter Physics, Leipzig University, 04103 Leipzig, Germany
| | - Klaus Kroy
- Institute for Theoretical Physics, Leipzig University, 04103 Leipzig, Germany
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57
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Vuijk HD, Merlitz H, Lang M, Sharma A, Sommer JU. Chemotaxis of Cargo-Carrying Self-Propelled Particles. PHYSICAL REVIEW LETTERS 2021; 126:208102. [PMID: 34110188 DOI: 10.1103/physrevlett.126.208102] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Accepted: 04/23/2021] [Indexed: 06/12/2023]
Abstract
Active particles with their characteristic feature of self-propulsion are regarded as the simplest models for motility in living systems. The accumulation of active particles in low activity regions has led to the general belief that chemotaxis requires additional features and at least a minimal ability to process information and to control motion. We show that self-propelled particles display chemotaxis and move into regions of higher activity if the particles perform work on passive objects, or cargo, to which they are bound. The origin of this cooperative chemotaxis is the exploration of the activity gradient by the active particle when bound to a load, resulting in an average excess force on the load in the direction of higher activity. Using a new theoretical model, we capture the most relevant features of these active-passive dimers, and in particular we predict the crossover between antichemotactic and chemotactic behavior. Moreover, we show that merely connecting active particles to chains is sufficient to obtain the crossover from antichemotaxis to chemotaxis with increasing chain length. Such an active complex is capable of moving up a gradient of activity such as provided by a gradient of fuel and to accumulate where the fuel concentration is at its maximum. The observed transition is of significance to protoforms of life, enabling them to locate a source of nutrients even in the absence of any supporting sensomotoric apparatus.
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Affiliation(s)
- Hidde D Vuijk
- Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden, Germany
| | - Holger Merlitz
- Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden, Germany
| | - Michael Lang
- Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden, Germany
| | - Abhinav Sharma
- Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden, Germany
- Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Deutschland
| | - Jens-Uwe Sommer
- Leibniz-Institut für Polymerforschung Dresden, Institut Theory der Polymere, 01069 Dresden, Germany
- Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Deutschland
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58
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Yang X, Chen Y, Zhou T, Zhang J. Exploring dissipative sources of non-Markovian biochemical reaction systems. Phys Rev E 2021; 103:052411. [PMID: 34134237 DOI: 10.1103/physreve.103.052411] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/29/2021] [Indexed: 11/07/2022]
Abstract
Many biological processes including important intracellular processes are governed by biochemical reaction networks. Usually, these reaction systems operate far from thermodynamic equilibrium, implying free-energy dissipation. On the other hand, single reaction events happen often in a memory manner, leading to non-Markovian kinetics. A question then arises: how do we calculate free-energy dissipation (defined as the entropy production rate) in this physically real case? We derive an analytical formula for calculating the energy consumption of a general reaction system with molecular memory characterized by nonexponential waiting-time distributions. It shows that this dissipation is composed of two parts: one from broken detailed balance of an equivalent Markovian system with the same topology and substrates, and the other from the direction-time dependence of waiting-time distributions. But, if the system is in a detailed balance and the waiting-time distribution is direction-time independent, there is no energy dissipation even in the non-Markovian case. These general results provide insights into the physical mechanisms underlying nonequilibrium processes. A continuous-time random-walk model and a generalized model of stochastic gene expression are chosen to clearly show dissipative sources and the relationship between energy dissipation and molecular memory.
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Affiliation(s)
- Xiyan Yang
- School of Financial Mathematics and Statistics, Guangdong University of Finance, Guangzhou 510521, People's Republic of China
| | - Yiren Chen
- College of Mathematics and Statistics, Shenzhen University, Shenzhen 518060, People's Republic of China
| | - Tianshou Zhou
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China.,Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China
| | - Jiajun Zhang
- School of Mathematics, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China.,Guangdong Province Key Laboratory of Computational Science, Guangzhou 510275, People's Republic of China
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59
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Cao XZ, Merlitz H, Wu CX, Forest MG. Chain stiffness boosts active nanoparticle transport in polymer networks. Phys Rev E 2021; 103:052501. [PMID: 34134347 DOI: 10.1103/physreve.103.052501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 04/27/2021] [Indexed: 11/07/2022]
Abstract
Recent advances in technologies such as nanomanufacturing and nanorobotics have opened new pathways for the design of active nanoparticles (NPs) capable of penetrating biolayers for biomedical applications, e.g., for drug delivery. The coupling and feedback between active NP motility (with large stochastic increments relative to passive NPs) and the induced nonequilibrium deformation and relaxation responses of the polymer network, spanning scales from the NP to the local structure of the network, remain to be clarified. Using molecular dynamics simulations, combined with a Rouse mode analysis of network chains and position and velocity autocorrelation functions of the NPs, we demonstrate that the mobility of active NPs within cross-linked, concentrated polymer networks is a monotonically increasing function of chain stiffness, contrary to passive NPs, for which chain stiffness suppresses mobility. In flexible networks, active NPs exhibit a behavior similar to passive NPs, with a boost in mobility proportional to the self-propulsion force. These results are suggestive of design strategies for active NP penetration of stiff biopolymer matrices.
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Affiliation(s)
- Xue-Zheng Cao
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
| | - Holger Merlitz
- Leibniz-Institut für Polymerforschung Dresden, 01069 Dresden, Germany
| | - Chen-Xu Wu
- Department of Physics, Xiamen University, Xiamen 361005, People's Republic of China
| | - M Gregory Forest
- Departments of Mathematics, Applied Physical Sciences, Biomedical Engineering, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3250, USA
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60
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Jose F, Anand SK, Singh SP. Phase separation of an active colloidal suspension via quorum-sensing. SOFT MATTER 2021; 17:3153-3161. [PMID: 33616149 DOI: 10.1039/d0sm02131h] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We present the Brownian dynamics simulation of an active colloidal suspension in two dimensions, where the self-propulsion speed of a colloid is regulated according to the local density sensed by it. The role of concentration-dependent motility in the phase-separation of colloids and their dynamics is investigated in detail. Interestingly, the system phase separates at a very low packing fraction (Φ≈ 0.125) at higher self-propulsion speeds (Pe), into a dense phase coexisting with a homogeneous phase and attains a long-range crystalline order beyond the transition point. The transition point is quantified here from the local density profiles and local and global-bond order parameters. We have shown that the characteristics of the phase diagram are qualitatively akin to the active Brownian particle (ABP) model. Moreover, our investigation reveals that the density-dependent motility amplifies the slow-down of the directed speed, which facilitates phase-separation even at low packing fractions. The effective diffusivity shows a crossover from quadratic rise to a power-law behavior of exponent 3/2 with Pe in the phase-separated regime. Furthermore, we have shown that the effective diffusion decreases exponentially with packing fraction in the phase-separated regime, while it shows a linear decrease in the single phase regime.
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Affiliation(s)
- Francis Jose
- Department of Physics, Indian Institute of Science Education and Research, Bhopal 462 066, Madhya Pradesh, India.
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61
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Grobas I, Polin M, Asally M. Swarming bacteria undergo localized dynamic phase transition to form stress-induced biofilms. eLife 2021; 10:62632. [PMID: 33722344 PMCID: PMC7963483 DOI: 10.7554/elife.62632] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 02/26/2021] [Indexed: 12/23/2022] Open
Abstract
Self-organized multicellular behaviors enable cells to adapt and tolerate stressors to a greater degree than isolated cells. However, whether and how cellular communities alter their collective behaviors adaptively upon exposure to stress is largely unclear. Here, we investigate this question using Bacillus subtilis, a model system for bacterial multicellularity. We discover that, upon exposure to a spatial gradient of kanamycin, swarming bacteria activate matrix genes and transit to biofilms. The initial stage of this transition is underpinned by a stress-induced multilayer formation, emerging from a biophysical mechanism reminiscent of motility-induced phase separation (MIPS). The physical nature of the process suggests that stressors which suppress the expansion of swarms would induce biofilm formation. Indeed, a simple physical barrier also induces a swarm-to-biofilm transition. Based on the gained insight, we propose a strategy of antibiotic treatment to inhibit the transition from swarms to biofilms by targeting the localized phase transition.
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Affiliation(s)
- Iago Grobas
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom
| | - Marco Polin
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom.,Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, United Kingdom.,Physics Department, University of Warwick, Coventry, United Kingdom.,Mediterranean Institute for Advanced Studies (IMEDEA UIB-CSIC), C/ Miquel Marqués, Balearic Islands, Spain
| | - Munehiro Asally
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry, United Kingdom.,Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, United Kingdom.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
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62
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Jakuszeit T, Lindsey-Jones J, Peaudecerf FJ, Croze OA. Migration and accumulation of bacteria with chemotaxis and chemokinesis. THE EUROPEAN PHYSICAL JOURNAL. E, SOFT MATTER 2021; 44:32. [PMID: 33721117 PMCID: PMC7960630 DOI: 10.1140/epje/s10189-021-00009-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 01/05/2021] [Indexed: 06/12/2023]
Abstract
Bacteria can chemotactically migrate up attractant gradients by controlling run-and-tumble motility patterns. In addition to this well-known chemotactic behaviour, several soil and marine bacterial species perform chemokinesis; they adjust their swimming speed according to the local concentration of chemoeffector, with higher speed at higher concentration. A field of attractant then induces a spatially varying swimming speed, which results in a drift towards lower attractant concentrations-contrary to the drift created by chemotaxis. Here, to explore the biological benefits of chemokinesis and investigate its impact on the chemotactic response, we extend a Keller-Segel-type model to include chemokinesis. We apply the model to predict the dynamics of bacterial populations capable of chemokinesis and chemotaxis in chemoeffector fields inspired by microfluidic and agar plate migration assays. We find that chemokinesis combined with chemotaxis not only may enhance the population response with respect to pure chemotaxis, but also modifies it qualitatively. We conclude presenting predictions for bacteria around dynamic finite-size nutrient sources, simulating, e.g. a marine particle or a root. We show that chemokinesis can reduce the measuring bias that is created by a decaying attractant gradient.
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Affiliation(s)
- Theresa Jakuszeit
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
| | | | - François J Peaudecerf
- Department of Civil, Environmental and Geomatic Engineering, Institute of Environmental Engineering, ETH Zürich, 8093, Zürich, Switzerland
| | - Ottavio A Croze
- Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, UK.
- Present address: School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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63
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Wang G, Phan TV, Li S, Wombacher M, Qu J, Peng Y, Chen G, Goldman DI, Levin SA, Austin RH, Liu L. Emergent Field-Driven Robot Swarm States. PHYSICAL REVIEW LETTERS 2021; 126:108002. [PMID: 33784150 DOI: 10.1103/physrevlett.126.108002] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 12/22/2020] [Accepted: 02/15/2021] [Indexed: 06/12/2023]
Abstract
We present an ecology-inspired form of active matter consisting of a robot swarm. Each robot moves over a planar dynamic resource environment represented by a large light-emitting diode array in search of maximum light intensity; the robots deplete (dim) locally by their presence the local light intensity and seek maximum light intensity. Their movement is directed along the steepest local light intensity gradient; we call this emergent symmetry breaking motion "field drive." We show there emerge dynamic and spatial transitions similar to gas, crystalline, liquid, glass, and jammed states as a function of robot density, resource consumption rates, and resource recovery rates. Paradoxically the nongas states emerge from smooth, flat resource landscapes, not rough ones, and each state can directly move to a glassy state if the resource recovery rate is slow enough, at any robot density.
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Affiliation(s)
- Gao Wang
- Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics, Chongqing University, Chongqing, 400044 China
| | - Trung V Phan
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Shengkai Li
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Michael Wombacher
- Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics, Chongqing University, Chongqing, 400044 China
| | - Junle Qu
- Key Laboratory of Optoelectronics Devices and Systems of Ministry of Education/Guangdong Province, College of Physics and Optoelectronic Engineering, Shenzhen University, Shenzhen, 518060 China
| | - Yan Peng
- Research Institute of USV Engineering, Shanghai University, Shanghai, 200444 China
| | - Guo Chen
- Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics, Chongqing University, Chongqing, 400044 China
| | - Daniel I Goldman
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Simon A Levin
- Department of Environmental and Evolutionary Biology, Princeton University, Princeton New Jersey 08544, USA
| | - Robert H Austin
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Liyu Liu
- Chongqing Key Laboratory of Soft Condensed Matter Physics and Smart Materials, College of Physics, Chongqing University, Chongqing, 400044 China
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64
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Martin D, O'Byrne J, Cates ME, Fodor É, Nardini C, Tailleur J, van Wijland F. Statistical mechanics of active Ornstein-Uhlenbeck particles. Phys Rev E 2021; 103:032607. [PMID: 33862678 DOI: 10.1103/physreve.103.032607] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2020] [Accepted: 12/23/2020] [Indexed: 06/12/2023]
Abstract
We study the statistical properties of active Ornstein-Uhlenbeck particles (AOUPs). In this simplest of models, the Gaussian white noise of overdamped Brownian colloids is replaced by a Gaussian colored noise. This suffices to grant this system the hallmark properties of active matter, while still allowing for analytical progress. We study in detail the steady-state distribution of AOUPs in the small persistence time limit and for spatially varying activity. At the collective level, we show AOUPs to experience motility-induced phase separation both in the presence of pairwise forces or due to quorum-sensing interactions. We characterize both the instability mechanism leading to phase separation and the resulting phase coexistence. We probe how, in the stationary state, AOUPs depart from their thermal equilibrium limit by investigating the emergence of ratchet currents and entropy production. In the small persistence time limit, we show how fluctuation-dissipation relations are recovered. Finally, we discuss how the emerging properties of AOUPs can be characterized from the dynamics of their collective modes.
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Affiliation(s)
- David Martin
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS,F-75205 Paris, France
| | - Jérémy O'Byrne
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS,F-75205 Paris, France
| | - Michael E Cates
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
| | - Étienne Fodor
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg
| | - Cesare Nardini
- DAMTP, Centre for Mathematical Sciences, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
- Service de Physique de l'État Condensé, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette, France
| | - Julien Tailleur
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS,F-75205 Paris, France
| | - Frédéric van Wijland
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS,F-75205 Paris, France
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65
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Abdoli I, Sharma A. Stochastic resetting of active Brownian particles with Lorentz force. SOFT MATTER 2021; 17:1307-1316. [PMID: 33313625 DOI: 10.1039/d0sm01773f] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Equilibrium properties of a system of passive diffusing particles in an external magnetic field are unaffected by Lorentz force. In contrast, active Brownian particles exhibit steady-state phenomena that depend on both the strength and the polarity of the applied magnetic field. The intriguing effects of the Lorentz force, however, can only be observed when out-of-equilibrium density gradients are maintained in the system. To this end, we use the method of stochastic resetting on active Brownian particles in two dimensions by resetting them to the line x = 0 at a constant rate and periodicity in the y direction. Under stochastic resetting, an active system settles into a nontrivial stationary state which is characterized by an inhomogeneous density distribution, polarization and bulk fluxes perpendicular to the density gradients. We show that whereas for a uniform magnetic field the properties of the stationary state of the active system can be obtained from its passive counterpart, novel features emerge in the case of an inhomogeneous magnetic field which have no counterpart in passive systems. In particular, there exists an activity-dependent threshold rate such that for smaller resetting rates, the density distribution of active particles becomes non-monotonic. We also study the mean first-passage time to the x axis and find a surprising result: it takes an active particle more time to reach the target from any given point for the case when the magnetic field increases away from the axis. The theoretical predictions are validated using Brownian dynamics simulations.
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Affiliation(s)
- Iman Abdoli
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Germany.
| | - Abhinav Sharma
- Leibniz-Institut für Polymerforschung Dresden, Institut Theorie der Polymere, 01069 Dresden, Germany. and Technische Universität Dresden, Institut für Theoretische Physik, 01069 Dresden, Germany
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66
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Holubec V, Marathe R. Underdamped active Brownian heat engine. Phys Rev E 2021; 102:060101. [PMID: 33466083 DOI: 10.1103/physreve.102.060101] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Accepted: 11/23/2020] [Indexed: 01/28/2023]
Abstract
Active Brownian engines rectify energy from reservoirs composed of self-propelling nonequilibrium molecules into work. We consider a class of such engines based on an underdamped Brownian particle trapped in a power-law potential. The energy they transform has thermodynamic properties of heat only if the nonequilibrium reservoir can be assigned a suitable effective temperature consistent with the second law and thus yielding an upper bound on the engine efficiency. The effective temperature exists if the total force exerted on the particle by the bath is not correlated with the particle position. In general, this occurs if the noise autocorrelation function and the friction kernel are proportional as in the fluctuation-dissipation theorem. But even if the proportionality is broken, the effective temperature can be defined in restricted, fine-tuned, parameter regimes, as we demonstrate on a specific example with harmonic potential.
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Affiliation(s)
- Viktor Holubec
- Institut für Theoretische Physik, Universität Leipzig, Postfach 100 920, D-04009 Leipzig, Germany.,Charles University, Faculty of Mathematics and Physics, Department of Macromolecular Physics, V Holešovičkách 2, CZ-180 00 Prague, Czech Republic
| | - Rahul Marathe
- Department of Physics, Indian Institute of Technology, Delhi, New Delhi 110016, India
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67
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Dandekar R, Chakraborti S, Rajesh R. Hard core run and tumble particles on a one-dimensional lattice. Phys Rev E 2021; 102:062111. [PMID: 33466079 DOI: 10.1103/physreve.102.062111] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Accepted: 11/16/2020] [Indexed: 11/07/2022]
Abstract
We study the large scale behavior of a collection of hard core run and tumble particles on a one-dimensional lattice with periodic boundary conditions. Each particle has persistent motion in one direction decided by an associated spin variable until the direction of spin is reversed. We map the run and tumble model to a mass transfer model with fluctuating directed bonds. We calculate the steady-state single-site mass distribution in the mass model within a mean field approximation for larger spin-flip rates and by analyzing an appropriate coalescence-fragmentation model for small spin-flip rates. We also calculate the hydrodynamic coefficients of diffusivity and conductivity for both large and small spin-flip rates and show that the Einstein relation is violated in both regimes. We also show how the nongradient nature of the process can be taken into account in a systematic manner to calculate the hydrodynamic coefficients.
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Affiliation(s)
- Rahul Dandekar
- The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai-600113, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai-400094, India
| | | | - R Rajesh
- The Institute of Mathematical Sciences, C.I.T. Campus, Taramani, Chennai-600113, India.,Homi Bhabha National Institute, Training School Complex, Anushakti Nagar, Mumbai-400094, India
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68
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Tiwari I, Parmananda P, Chelakkot R. Periodic oscillations in a string of camphor infused disks. SOFT MATTER 2020; 16:10334-10344. [PMID: 33237113 DOI: 10.1039/d0sm01393e] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The rhythmic beating motion of autonomously motile filaments has many practical applications. Here, we present an experimental study on a filament made of camphor infused paper disks, stitched together adjacent to each other using nylon thread. The filament displays spontaneous translatory motion when it is placed on the surface of water due to the surface tension gradients created by camphor molecules on the water surface. When this filament is clamped on one end, we obtain regular oscillatory motion instead of translation. The filament shows qualitatively different dynamics at different activity levels, which is controlled by the amount of camphor infused into the paper disks. For a better physical understanding of the filament dynamics, we develop a minimal numerical model involving a semi-flexible filament made of active polar disks, where the polarity is coupled to the instantaneous velocity of the particle. This model qualitatively reproduces different oscillatory modes of the filament. Moreover, our model reveals a rich dynamical state diagram of the system, as a function of filament activity and the coupling strength.
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Affiliation(s)
- Ishant Tiwari
- Department of Physics, Indian Institute of Technology - Bombay, Mumbai, Maharashtra 400076, India.
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69
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O'Byrne J, Tailleur J. Lamellar to Micellar Phases and Beyond: When Tactic Active Systems Admit Free Energy Functionals. PHYSICAL REVIEW LETTERS 2020; 125:208003. [PMID: 33258650 DOI: 10.1103/physrevlett.125.208003] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 10/14/2020] [Indexed: 06/12/2023]
Abstract
We consider microscopic models of active particles whose velocities, rotational diffusivities, and tumbling rates depend on the gradient of a local field that is either externally imposed or depends on all particle positions. Despite the fundamental differences between active and passive dynamics at the microscopic scale, we show that a large class of such tactic active systems admit fluctuating hydrodynamics equivalent to those of interacting Brownian colloids in equilibrium. We exploit this mapping to show how taxis may lead to the lamellar and micellar phases observed for soft repulsive colloids. In the context of chemotaxis, we show how the competition between chemoattractant and chemorepellent may lead to a bona fide equilibrium liquid-gas phase separation in which a loss of thermodynamic stability of the fluid signals the onset of a chemotactic collapse.
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Affiliation(s)
- J O'Byrne
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
| | - J Tailleur
- Université de Paris, Laboratoire Matière et Systèmes Complexes (MSC), UMR 7057 CNRS, F-75205 Paris, France
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70
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Ishikawa T, Omori T, Kikuchi K. Bacterial biomechanics-From individual behaviors to biofilm and the gut flora. APL Bioeng 2020; 4:041504. [PMID: 33163845 PMCID: PMC7595747 DOI: 10.1063/5.0026953] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2020] [Accepted: 10/16/2020] [Indexed: 02/07/2023] Open
Abstract
Bacteria inhabit a variety of locations and play important roles in the environment and health. Our understanding of bacterial biomechanics has improved markedly in the last decade and has revealed that biomechanics play a significant role in microbial biology. The obtained knowledge has enabled investigation of complex phenomena, such as biofilm formation and the dynamics of the gut flora. A bottom-up strategy, i.e., from the cellular to the macroscale, facilitates understanding of macroscopic bacterial phenomena. In this Review, we first cover the biomechanics of individual bacteria in the bulk liquid and on surfaces as the base of complex phenomena. The collective behaviors of bacteria in simple environments are next introduced. We then introduce recent advances in biofilm biomechanics, in which adhesion force and the flow environment play crucial roles. We also review transport phenomena in the intestine and the dynamics of the gut flora, focusing on that in zebrafish. Finally, we provide an overview of the future prospects for the field.
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Affiliation(s)
| | - Toshihiro Omori
- Department Finemechanics, Graduate School of Engineering, Tohoku University, Sendai 980-8579, Japan
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71
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Abstract
This paper generalizes isomorph theory to systems that are not in thermal equilibrium. The systems are assumed to be R-simple, i.e., to have a potential energy that as a function of all particle coordinates R obeys the hidden-scale-invariance condition U(Ra) < U(Rb) ⇒ U(λRa) < U(λRb). "Systemic isomorphs" are introduced as lines of constant excess entropy in the phase diagram defined by density and systemic temperature, which is the temperature of the equilibrium state point with the average potential energy equal to U(R). The dynamics is invariant along a systemic isomorph if there is a constant ratio between the systemic and the bath temperature. In thermal equilibrium, the systemic temperature is equal to the bath temperature and the original isomorph formalism is recovered. The new approach rationalizes within a consistent framework previously published observations of isomorph invariance in simulations involving nonlinear steady-state shear flows, zero-temperature plastic flows, and glass-state isomorphs. This paper relates briefly to granular media, physical aging, and active matter. Finally, we discuss the possibility that the energy unit defining the reduced quantities should be based on the systemic rather than the bath temperature.
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Affiliation(s)
- Jeppe C Dyre
- Glass and Time, IMFUFA, Department of Science and Environment, Roskilde University, P.O. Box 260, DK-4000 Roskilde, Denmark
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72
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Mori F, Le Doussal P, Majumdar SN, Schehr G. Universal properties of a run-and-tumble particle in arbitrary dimension. Phys Rev E 2020; 102:042133. [PMID: 33212668 DOI: 10.1103/physreve.102.042133] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 08/18/2020] [Indexed: 06/11/2023]
Abstract
We consider an active run-and-tumble particle (RTP) in d dimensions, starting from the origin and evolving over a time interval [0,t]. We examine three different models for the dynamics of the RTP: the standard RTP model with instantaneous tumblings, a variant with instantaneous runs and a general model in which both the tumblings and the runs are noninstantaneous. For each of these models, we use the Sparre Andersen theorem for discrete-time random walks to compute exactly the probability that the x component does not change sign up to time t, showing that it does not depend on d. As a consequence of this result, we compute exactly other x-component properties, namely, the distribution of the time of the maximum and the record statistics, showing that they are universal, i.e., they do not depend on d. Moreover, we show that these universal results hold also if the speed v of the particle after each tumbling is random, drawn from a generic probability distribution. Our findings are confirmed by numerical simulations. Some of these results have been announced in a recent Letter [Phys. Rev. Lett. 124, 090603 (2020)10.1103/PhysRevLett.124.090603].
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Affiliation(s)
- Francesco Mori
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Pierre Le Doussal
- Laboratoire de Physique de l'Ecole Normale Supérieure, PSL University, CNRS, Sorbonne Universités, 24 rue Lhomond, 75231 Paris, France
| | - Satya N Majumdar
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Grégory Schehr
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
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73
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Szamel G. Single active particle engine utilizing a nonreciprocal coupling between particle position and self-propulsion. Phys Rev E 2020; 102:042605. [PMID: 33212595 DOI: 10.1103/physreve.102.042605] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 09/21/2020] [Indexed: 11/07/2022]
Abstract
We recently argued that a self-propelled particle is formally equivalent to a system consisting of two subsystems coupled by a nonreciprocal interaction [Phys. Rev. E 100, 050603(R) (2019)2470-004510.1103/PhysRevE.100.050603]. Here, we show that this nonreciprocal coupling allows us to extract useful work from a single self-propelled particle maintained at constant temperature, by using an aligning interaction to control correlations between the particle's position and self-propulsion.
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Affiliation(s)
- Grzegorz Szamel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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74
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Thornton KL, Butler JK, Davis SJ, Baxter BK, Wilson LG. Haloarchaea swim slowly for optimal chemotactic efficiency in low nutrient environments. Nat Commun 2020; 11:4453. [PMID: 32901025 PMCID: PMC7478972 DOI: 10.1038/s41467-020-18253-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 08/05/2020] [Indexed: 01/18/2023] Open
Abstract
Archaea have evolved to survive in some of the most extreme environments on earth. Life in extreme, nutrient-poor conditions gives the opportunity to probe fundamental energy limitations on movement and response to stimuli, two essential markers of living systems. Here we use three-dimensional holographic microscopy and computer simulations to reveal that halophilic archaea achieve chemotaxis with power requirements one hundred-fold lower than common eubacterial model systems. Their swimming direction is stabilised by their flagella (archaella), enhancing directional persistence in a manner similar to that displayed by eubacteria, albeit with a different motility apparatus. Our experiments and simulations reveal that the cells are capable of slow but deterministic chemotaxis up a chemical gradient, in a biased random walk at the thermodynamic limit.
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Affiliation(s)
- Katie L Thornton
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK
| | - Jaimi K Butler
- Great Salt Lake Institute, Westminster College, 1840 South 1300 East, Salt Lake City, UT, 84105, USA
| | - Seth J Davis
- Department of Biology, University of York, Heslington, York, YO10 5DD, UK
- State Key Laboratory of Crop Stress Biology, School of Life Sciences, Henan University, 475004, Kaifeng, China
| | - Bonnie K Baxter
- Great Salt Lake Institute, Westminster College, 1840 South 1300 East, Salt Lake City, UT, 84105, USA
| | - Laurence G Wilson
- Department of Physics, University of York, Heslington, York, YO10 5DD, UK.
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75
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Škultéty V, Birnšteinová Š, Lučivjanský T, Honkonen J. Universality in incompressible active fluid: Effect of nonlocal shear stress. Phys Rev E 2020; 102:032616. [PMID: 33075957 DOI: 10.1103/physreve.102.032616] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2020] [Accepted: 07/20/2020] [Indexed: 06/11/2023]
Abstract
Phase transitions in active fluids attracted significant attention within the last decades. Recent results show [L. Chen et al., New J. Phys. 17, 042002 (2015)10.1088/1367-2630/17/4/042002] that an order-disorder phase transition in incompressible active fluids belongs to a new universality class. In this work, we further investigate this type of phase transition and focus on the effect of long-range interactions. This is achieved by introducing a nonlocal shear stress into the hydrodynamic description, which leads to superdiffusion of the velocity field, and can be viewed as a result of the active particles performing Lévy walks. The universal properties in the critical region are derived by performing a perturbative renormalization group analysis of the corresponding response functional within the one-loop approximation. We show that the effect of nonlocal shear stress decreases the upper critical dimension of the model, and can lead to the irrelevance of the active fluid self-advection with the resulting model belonging to an unusual long-range Model A universality class not reported before, to our knowledge. Moreover, when the degree of nonlocality is sufficiently high all nonlinearities become irrelevant and the mean-field description is valid in any spatial dimension.
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Affiliation(s)
- V Škultéty
- SUPA, School of Physics and Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, Edinburgh EH9 3FD, United Kingdom
| | - Š Birnšteinová
- Faculty of Sciences, P. J. Šafárik University, 04154 Košice, Slovakia
| | - T Lučivjanský
- Faculty of Sciences, P. J. Šafárik University, 04154 Košice, Slovakia
| | - J Honkonen
- Department of Military Technology, National Defence University, P.O. Box 7, 00861 Helsinki, Finland
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76
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Sachs J, Kottapalli SN, Fischer P, Botin D, Palberg T. Characterization of active matter in dense suspensions with heterodyne laser Doppler velocimetry. Colloid Polym Sci 2020. [DOI: 10.1007/s00396-020-04693-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AbstractWe present a novel approach for characterizing the properties and performance of active matter in dilute suspension as well as in crowded environments. We use Super-Heterodyne Laser-Doppler-Velocimetry (SH-LDV) to study large ensembles of catalytically active Janus particles moving under UV illumination. SH-LDV facilitates a model-free determination of the swimming speed and direction, with excellent ensemble averaging. In addition, we obtain information on the distribution of the catalytic activity. Moreover, SH-LDV operates away from walls and permits a facile correction for multiple scattering contributions. It thus allows for studies of concentrated suspensions of swimmers or of systems where swimmers propel actively in an environment crowded by passive particles. We demonstrate the versatility and the scope of the method with a few selected examples. We anticipate that SH-LDV complements established methods and paves the way for systematic measurements at previously inaccessible boundary conditions.
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77
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Giannini JA, Puckett JG. Testing a thermodynamic approach to collective animal behavior in laboratory fish schools. Phys Rev E 2020; 101:062605. [PMID: 32688602 DOI: 10.1103/physreve.101.062605] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/08/2020] [Indexed: 11/07/2022]
Abstract
Collective behaviors displayed by groups of social animals are observed frequently in nature. Understanding and predicting the behavior of complex biological systems is dependent on developing effective descriptions and models. While collective animal systems are characteristically nonequilibrium, we can employ concepts from equilibrium statistical mechanics to motivate the measurement of material-like properties in laboratory animal aggregates. Here, we present results from a new set of experiments that utilize high speed footage of two-dimensional schooling events, particle tracking, and projected static and dynamic light fields to observe and control the behavior of negatively phototaxic fish schools (Hemigrammus bleheri). First, we use static light fields consisting of dark circular regions to produce visual stimuli that confine the schools to a range of areas. We find that schools have a maximum density which is independent of group size, and that a swim pressurelike quantity, Π increases linearly with number density, suggesting that unperturbed schools exist on an isotherm. Next, we use dynamic light fields where the radius of the dark region shrinks linearly with time to compress the schools. We find that an effective temperature parameter depends on the compression time and our results are thus consistent with the school having a constant heat flux. These findings further evidence the utility of effective thermodynamic descriptions of nonequilibrium systems in collective animal behavior.
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Affiliation(s)
- Julia A Giannini
- Department of Physics, Syracuse University, Syracuse, New York 13244, USA
| | - James G Puckett
- Department of Physics, Gettysburg College, Gettysburg, Pennsylvania 17325, USA
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78
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Li K, Guo F, Zhou X, Wang X, He L, Zhang L. An attraction-repulsion transition of force on two asymmetric wedges induced by active particles. Sci Rep 2020; 10:11702. [PMID: 32678189 PMCID: PMC7367348 DOI: 10.1038/s41598-020-68677-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 05/21/2020] [Indexed: 02/04/2023] Open
Abstract
Effective interaction between two asymmetric wedges immersed in a two-dimensional active bath is investigated by computer simulations. The attraction–repulsion transition of effective force between two asymmetric wedges is subjected to the relative position of two wedges, the wedge-to-wedge distance, the active particle density, as well as the apex angle of two wedges. By exchanging the position of the two asymmetric wedges in an active bath, firstly a simple attraction–repulsion transition of effective force occurs, completely different from passive Brownian particles. Secondly the transition of effective force is symmetric for the long-range distance between two asymmetric wedges, while it is asymmetric for the short-range case. Our investigations may provide new possibilities to govern the motion and assembly of microscopic objects by taking advantage of the self-driven behaviour of active particles.
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Affiliation(s)
- Ke Li
- Department of Physics, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Fuchen Guo
- Department of Physics, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Xiaolin Zhou
- Department of Physics, Zhejiang University, Hangzhou, 310027, Zhejiang, China
| | - Xianghong Wang
- Department of Physics, Wenzhou University, Wenzhou, 325035, Zhejiang, China
| | - Linli He
- Department of Physics, Wenzhou University, Wenzhou, 325035, Zhejiang, China.
| | - Linxi Zhang
- Department of Physics, Zhejiang University, Hangzhou, 310027, Zhejiang, China.
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79
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Paoluzzi M, Leoni M, Marchetti MC. Information and motility exchange in collectives of active particles. SOFT MATTER 2020; 16:6317-6327. [PMID: 32578662 DOI: 10.1039/d0sm00204f] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We examine the interplay of motility and information exchange in a model of run-and-tumble active particles where the particle's motility is encoded as a bit of information that can be exchanged upon contact according to the rules of AND and OR logic gates in a circuit. Motile AND particles become non-motile upon contact with a non-motile particle. Conversely, motile OR particles remain motile upon collision with their non-motile counterparts. AND particles that have become non-motile additionally "reawaken", i.e., recover their motility, at a fixed rate μ, as in the SIS (susceptible, infected, susceptible) model of epidemic spreading, where an infected agent can become healthy again, but keeps no memory of the recent infection, hence it is susceptible to a renewed infection. For μ = 0, both AND and OR particles relax irreversibly to absorbing states of all non-motile or all motile particles, respectively. The relaxation kinetics is, however, faster for OR particles that remain active throughout the process. At finite μ, the AND dynamics is controlled by the interplay between reawakening and collision rates. The system evolves to a state of all motile particles (an absorbing state in the language of absorbing phase transitions) for μ > μc and to a mixed state with coexisting motile and non-motile particles (an active state in the language of absorbing phase transitions) for μ < μc. The final state exhibits a rich structure controlled by motility-induced aggregation. Our work can be relevant to biochemical signaling in motile bacteria, the spreading of epidemics and of social consensus, as well as light-controlled organization of active colloids.
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Affiliation(s)
- Matteo Paoluzzi
- ISC-CNR, Institute for Complex Systems, Piazzale A. Moro 2, I-00185 Rome, Italy. and Dipartimento di Fisica, Sapienza University of Rome, Piazzale A. Moro 2, I-00185, Rome, Italy
| | - Marco Leoni
- Université Paris-Saclay, CNRS, IJCLab, 91405, Orsay, France.
| | - M Cristina Marchetti
- Department of Physics, University of California Santa Barbara, Santa Barbara, CA 93106, USA
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80
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Bárdfalvy D, Anjum S, Nardini C, Morozov A, Stenhammar J. Symmetric Mixtures of Pusher and Puller Microswimmers Behave as Noninteracting Suspensions. PHYSICAL REVIEW LETTERS 2020; 125:018003. [PMID: 32678625 DOI: 10.1103/physrevlett.125.018003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Suspensions of rear- and front-actuated microswimmers immersed in a fluid, known respectively as "pushers" and "pullers," display qualitatively different collective behaviors: beyond a characteristic density, pusher suspensions exhibit a hydrodynamic instability leading to collective motion known as active turbulence, a phenomenon which is absent for pullers. In this Letter, we describe the collective dynamics of a binary pusher-puller mixture using kinetic theory and large-scale particle-resolved simulations. We derive and verify an instability criterion, showing that the critical density for active turbulence moves to higher values as the fraction χ of pullers is increased and disappears for χ≥0.5. We then show analytically and numerically that the two-point hydrodynamic correlations of the 1∶1 mixture are equal to those of a suspension of noninteracting swimmers. Strikingly, our numerical analysis furthermore shows that the full probability distribution of the fluid velocity fluctuations collapses onto the one of a noninteracting system at the same density, where swimmer-swimmer correlations are strictly absent. Our results thus indicate that the fluid velocity fluctuations in 1∶1 pusher-puller mixtures are exactly equal to those of the corresponding noninteracting suspension at any density, a surprising cancellation with no counterpart in equilibrium long-range interacting systems.
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Affiliation(s)
- Dóra Bárdfalvy
- Division of Physical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
| | - Shan Anjum
- Division of Physical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
| | - Cesare Nardini
- Service de Physique de l'État Condensé, CNRS UMR 3680, CEA-Saclay, 91191 Gif-sur-Yvette, France
- Sorbonne Université, CNRS, Laboratoire de Physique Théorique de la Matière Condensée, LPTMC, F-75005 Paris, France
| | - Alexander Morozov
- SUPA, School of Physics and Astronomy, The University of Edinburgh, James Clerk Maxwell Building, Peter Guthrie Tait Road, Edinburgh, EH9 3FD, United Kingdom
| | - Joakim Stenhammar
- Division of Physical Chemistry, Lund University, P.O. Box 124, S-221 00 Lund, Sweden
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81
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Santra I, Basu U, Sabhapandit S. Run-and-tumble particles in two dimensions: Marginal position distributions. Phys Rev E 2020; 101:062120. [PMID: 32688530 DOI: 10.1103/physreve.101.062120] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 05/29/2020] [Indexed: 06/11/2023]
Abstract
We study a set of run-and-tumble particle (RTP) dynamics in two spatial dimensions. In the first case of the orientation θ of the particle can assume a set of n possible discrete values, while in the second case θ is a continuous variable. We calculate exactly the marginal position distributions for n=3,4 and the continuous case and show that in all cases the RTP shows a crossover from a ballistic to diffusive regime. The ballistic regime is a typical signature of the active nature of the systems and is characterized by nontrivial position distributions which depend on the specific model. We also show that the signature of activity at long times can be found in the atypical fluctuations, which we also characterize by computing the large deviation functions explicitly.
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Affiliation(s)
- Ion Santra
- Raman Research Institute, Bengaluru 560080, India
| | - Urna Basu
- Raman Research Institute, Bengaluru 560080, India
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82
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Ai BQ, Zhou BY, Zhang XM. Binary mixtures of active and passive particles on a sphere. SOFT MATTER 2020; 16:4710-4717. [PMID: 32367106 DOI: 10.1039/d0sm00281j] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We study the cooperation and segregation dynamics of binary mixtures of active and passive particles on a sphere. According to the competition between rotational diffusion and polar alignment, we find three distinct phases: a mixed phase and two different demixed phases. When rotational diffusion dominates the dynamics, the demixing is due to the aggregation of passive particles, where active and passive particles respectively occupy two hemispheres. When polar alignment is dominated, the demixing is caused by the aggregation of active particles, where active particles occupy the equator of the sphere and passive particles occupy the two poles of the sphere. In this case, there exist a circulating band cluster and two cambered surface clusters, which is a purely curvature-driven effect with no equivalent in the planar model. When rotational diffusion and polar alignment are comparable, particles are completely mixed. Our findings are relevant to the experimental pursuit of segregation dynamics of binary mixtures on curved surfaces.
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Affiliation(s)
- Bao-Quan Ai
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, GPETR Center for Quantum Precision Measurement, SPTE, South China Normal University, Guangzhou 510006, China.
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83
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Bäuerle T, Löffler RC, Bechinger C. Formation of stable and responsive collective states in suspensions of active colloids. Nat Commun 2020; 11:2547. [PMID: 32439919 PMCID: PMC7242396 DOI: 10.1038/s41467-020-16161-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Accepted: 04/20/2020] [Indexed: 12/24/2022] Open
Abstract
Many animal species organise into disordered swarms, polarised flocks or swirls to protect from predators or optimise foraging. Previous studies suggest that such collective states are related to a critical point, which could explain their balance between robustness to noise and high responsiveness regarding external perturbations. Here we provide experimental evidence for this idea by investigating the stability of swirls formed by light-responsive active colloids which adjust their individual motion to positions and orientations of neighbours. Because their behaviour can be precisely tuned, controlled changes between different collective states can be achieved. During the transition between stable swirls and swarms we observe a maximum of the group's susceptibility indicating the vicinity of a critical point. Our results support the idea of system-independent organisation principles of collective states and provide useful strategies for the realisation of responsive yet stable ensembles in microrobotic systems.
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Affiliation(s)
- Tobias Bäuerle
- Fachbereich Physik, Universität Konstanz, Konstanz, D-78464, Germany
| | - Robert C Löffler
- Fachbereich Physik, Universität Konstanz, Konstanz, D-78464, Germany
| | - Clemens Bechinger
- Fachbereich Physik, Universität Konstanz, Konstanz, D-78464, Germany.
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84
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Liverpool TB. Steady-state distributions and nonsteady dynamics in nonequilibrium systems. Phys Rev E 2020; 101:042107. [PMID: 32422705 DOI: 10.1103/physreve.101.042107] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2018] [Accepted: 02/10/2020] [Indexed: 11/07/2022]
Abstract
We search for steady states in a class of fluctuating and driven physical systems that exhibit sustained currents. We find that the physical concept of a steady state, well known for systems at equilibrium, must be generalized to describe such systems. In these, the generalization of a steady state is associated with a stationary probability density of microstates and a deterministic dynamical system whose trajectories the system follows on average. These trajectories are a manifestation of nonstationary macroscopic currents observed in these systems. We determine precise conditions for the steady state to exist as well as the requirements for it to be stable. We illustrate this with some examples.
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85
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Abstract
Due to its inherent out-of-equilibrium nature, active matter in confinement may exhibit collective behavior absent in unconfined systems. Extensive studies have indicated that hydrodynamic or steric interactions between active particles and boundary play an important role in the emergence of collective behavior. However, besides introducing external couplings at the single-particle level, the confinement also induces an inhomogeneous density distribution due to particle-position correlations, whose effect on collective behavior remains unclear. Here, we investigate this effect in a minimal chiral active matter composed of self-spinning rotors through simulation, experiment, and theory. We find that the density inhomogeneity leads to a position-dependent frictional stress that results from interrotor friction and couples the spin to the translation of the particles, which can then drive a striking spatially oscillating collective motion of the chiral active matter along the confinement boundary. Moreover, depending on the oscillation properties, the collective behavior has three different modes as the packing fraction varies. The structural origins of the transitions between the different modes are well identified by the percolation of solid-like regions or the occurrence of defect-induced particle rearrangement. Our results thus show that the confinement-induced inhomogeneity, dynamic structure, and compressibility have significant influences on collective behavior of active matter and should be properly taken into account.
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86
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Gompper G, Winkler RG, Speck T, Solon A, Nardini C, Peruani F, Löwen H, Golestanian R, Kaupp UB, Alvarez L, Kiørboe T, Lauga E, Poon WCK, DeSimone A, Muiños-Landin S, Fischer A, Söker NA, Cichos F, Kapral R, Gaspard P, Ripoll M, Sagues F, Doostmohammadi A, Yeomans JM, Aranson IS, Bechinger C, Stark H, Hemelrijk CK, Nedelec FJ, Sarkar T, Aryaksama T, Lacroix M, Duclos G, Yashunsky V, Silberzan P, Arroyo M, Kale S. The 2020 motile active matter roadmap. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:193001. [PMID: 32058979 DOI: 10.1088/1361-648x/ab6348] [Citation(s) in RCA: 150] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Activity and autonomous motion are fundamental in living and engineering systems. This has stimulated the new field of 'active matter' in recent years, which focuses on the physical aspects of propulsion mechanisms, and on motility-induced emergent collective behavior of a larger number of identical agents. The scale of agents ranges from nanomotors and microswimmers, to cells, fish, birds, and people. Inspired by biological microswimmers, various designs of autonomous synthetic nano- and micromachines have been proposed. Such machines provide the basis for multifunctional, highly responsive, intelligent (artificial) active materials, which exhibit emergent behavior and the ability to perform tasks in response to external stimuli. A major challenge for understanding and designing active matter is their inherent nonequilibrium nature due to persistent energy consumption, which invalidates equilibrium concepts such as free energy, detailed balance, and time-reversal symmetry. Unraveling, predicting, and controlling the behavior of active matter is a truly interdisciplinary endeavor at the interface of biology, chemistry, ecology, engineering, mathematics, and physics. The vast complexity of phenomena and mechanisms involved in the self-organization and dynamics of motile active matter comprises a major challenge. Hence, to advance, and eventually reach a comprehensive understanding, this important research area requires a concerted, synergetic approach of the various disciplines. The 2020 motile active matter roadmap of Journal of Physics: Condensed Matter addresses the current state of the art of the field and provides guidance for both students as well as established scientists in their efforts to advance this fascinating area.
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Affiliation(s)
- Gerhard Gompper
- Theoretical Soft Matter and Biophysics, Institute of Complex Systems and Institute for Advanced Simulation, Forschungszentrum Jülich, 52425 Jülich, Germany
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87
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Merlitz H, Vuijk HD, Wittmann R, Sharma A, Sommer JU. Pseudo-chemotaxis of active Brownian particles competing for food. PLoS One 2020; 15:e0230873. [PMID: 32267868 PMCID: PMC7141648 DOI: 10.1371/journal.pone.0230873] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2019] [Accepted: 03/10/2020] [Indexed: 01/05/2023] Open
Abstract
Active Brownian particles (ABPs) are physical models for motility in simple life forms and easily studied in simulations. An open question is to what extent an increase of activity by a gradient of fuel, or food in living systems, results in an evolutionary advantage of actively moving systems such as ABPs over non-motile systems, which rely on thermal diffusion only. It is an established fact that within confined systems in a stationary state, the activity of ABPs generates density profiles that are enhanced in regions of low activity, which is thus referred to as ‘anti-chemotaxis’. This would suggest that a rather complex sensoric subsystem and information processing is a precondition to recognize and navigate towards a food source. We demonstrate in this work that in non-stationary setups, for instance as a result of short bursts of fuel/food, ABPs do in fact exhibit chemotactic behavior. In direct competition with inactive, but otherwise identical Brownian particles (BPs), the ABPs are shown to fetch a larger amount of food. We discuss this result based on simple physical arguments. From the biological perspective, the ability of primitive entities to move in direct response to the available amount of external energy would, even in absence of any sensoric devices, encompass an evolutionary advantage.
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Affiliation(s)
- Holger Merlitz
- Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
- * E-mail:
| | - Hidde D. Vuijk
- Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
| | - René Wittmann
- Institut für Theoretische Physik II, Weiche Materie, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany
| | - Abhinav Sharma
- Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
| | - Jens-Uwe Sommer
- Institut Theorie der Polymere, Leibniz-Institut für Polymerforschung Dresden, Dresden, Germany
- Technische Universität Dresden, Institut für Theoretische Physik, Dresden, Germany
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88
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Manikandan SK, Gupta D, Krishnamurthy S. Inferring Entropy Production from Short Experiments. PHYSICAL REVIEW LETTERS 2020; 124:120603. [PMID: 32281844 DOI: 10.1103/physrevlett.124.120603] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 02/18/2020] [Indexed: 06/11/2023]
Abstract
We provide a strategy for the exact inference of the average as well as the fluctuations of the entropy production in nonequilibrium systems in the steady state, from the measurements of arbitrary current fluctuations. Our results are built upon the finite-time generalization of the thermodynamic uncertainty relation, and require only very short time series data from experiments. We illustrate our results with exact and numerical solutions for two colloidal heat engines.
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Affiliation(s)
| | - Deepak Gupta
- Dipartimento di Fisica "G. Galilei," INFN, Università di Padova, Via Marzolo 8, 35131 Padova, Italy
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89
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Mori F, Le Doussal P, Majumdar SN, Schehr G. Universal Survival Probability for a d-Dimensional Run-and-Tumble Particle. PHYSICAL REVIEW LETTERS 2020; 124:090603. [PMID: 32202896 DOI: 10.1103/physrevlett.124.090603] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2019] [Accepted: 02/05/2020] [Indexed: 06/10/2023]
Abstract
We consider an active run-and-tumble particle (RTP) in d dimensions and compute exactly the probability S(t) that the x component of the position of the RTP does not change sign up to time t. When the tumblings occur at a constant rate, we show that S(t) is independent of d for any finite time t (and not just for large t), as a consequence of the celebrated Sparre Andersen theorem for discrete-time random walks in one dimension. Moreover, we show that this universal result holds for a much wider class of RTP models in which the speed v of the particle after each tumbling is random, drawn from an arbitrary probability distribution. We further demonstrate, as a consequence, the universality of the record statistics in the RTP problem.
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Affiliation(s)
- Francesco Mori
- LPTMS, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Pierre Le Doussal
- Laboratoire de Physique de l'Ecole Normale Supérieure, PSL University, CNRS, Sorbonne Universités, 24 rue Lhomond, 75231 Paris, France
| | - Satya N Majumdar
- LPTMS, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Grégory Schehr
- LPTMS, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
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90
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Cao X, Zhang B, Zhao N. Effective temperature scaled dynamics of a flexible polymer in an active bath. Mol Phys 2020. [DOI: 10.1080/00268976.2020.1730992] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Xiuli Cao
- College of Chemistry, Sichuan University, Chengdu, China
| | - Bingjie Zhang
- College of Chemistry, Sichuan University, Chengdu, China
| | - Nanrong Zhao
- College of Chemistry, Sichuan University, Chengdu, China
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91
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Abstract
The use of nanomaterials to regulate cell surface receptors is considered a novel strategy to manipulate cell behaviors. However, recognition is important to drive nanoparticle-cell complex formation. Here, we report a novel approach that uses graphene oxide (GO) as a chemoattractant to lure bacteria to nanosurface, facilitating complex formation. The amount of Escherichia coli (E. coli) cells attracted into capillaries containing 20 mg/L GO was more than 8.6-fold higher than that attracted into capillaries containing 20 mg/L glucose. The inherent mechanism involved interference with transmembrane chemoreceptors and activation of the chemotactic system via GO attachment and a subsequent increase in cell aggregation and migration via self-secreted quorum sensing molecules. The key feature of this strategy is the potential to improve the efficiency of the nanoparticle-cell recognition pattern and to expedite the development of surface-contact-related nanotechnology.
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Affiliation(s)
- Chengdong Zhang
- School of Environment , Beijing Normal University , Xin Jie Kou Wai ST 19 , Beijing 100875 , China
| | - Yaqi Wang
- College of Environmental Science and Engineering , Nankai University , Tong Yan Rd. 38 , Tianjin 300350 , China
| | - Huiru Zhao
- College of Environmental Science and Engineering , Nankai University , Tong Yan Rd. 38 , Tianjin 300350 , China
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92
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93
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A combined rheometry and imaging study of viscosity reduction in bacterial suspensions. Proc Natl Acad Sci U S A 2020; 117:2326-2331. [PMID: 31964833 PMCID: PMC7007524 DOI: 10.1073/pnas.1912690117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Suspending self-propelled "pushers" in a liquid lowers its viscosity. We study how this phenomenon depends on system size in bacterial suspensions using bulk rheometry and particle-tracking rheoimaging. Above the critical bacterial volume fraction needed to decrease the viscosity to zero, [Formula: see text], large-scale collective motion emerges in the quiescent state, and the flow becomes nonlinear. We confirm a theoretical prediction that such instability should be suppressed by confinement. Our results also show that a recent application of active liquid-crystal theory to such systems is untenable.
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94
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Das R, Kumar M, Mishra S. Nonquenched rotators ease flocking and memorize it. Phys Rev E 2020; 101:012607. [PMID: 32069681 DOI: 10.1103/physreve.101.012607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Indexed: 02/03/2023]
Abstract
We introduce a minimal model for a two-dimensional polar flock with nonquenched rotators and show that the rotators make the usual macroscopic long-range order of the flock more robust than the clean system. The rotators memorize the flock-information which helps in establishing the robustness. Moreover, the memory of the rotators assists in probing the moving flock. We also formulate a hydrodynamic framework for the microscopic model that makes our study comprehensive. Using linearized hydrodynamics, it is shown that the presence of such nonquenched heterogeneities increases the sound speeds of the flock. The enhanced sound speeds lead to faster convection of information and consequently the robust ordering in the system. We argue that similar nonquenched heterogeneities may be useful in monitoring and controlling large crowds.
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Affiliation(s)
- Rakesh Das
- S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Manoranjan Kumar
- S N Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700106, India
| | - Shradha Mishra
- Department of Physics, Indian Institute of Technology (BHU), Varanasi 221005, India
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95
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Angelani L, Garra R. Run-and-tumble motion in one dimension with space-dependent speed. Phys Rev E 2019; 100:052147. [PMID: 31869950 DOI: 10.1103/physreve.100.052147] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Indexed: 11/07/2022]
Abstract
We consider a particle performing run-and-tumble dynamics with space-dependent speed. The model has biological relevance as it describes motile bacteria or cells in heterogeneous environments. We give exact expression for the probability density function in the case of free motion in unbounded space. We then analyze the case of a particle moving in a confined interval in the presence of partially absorbing boundaries, reporting the probability density in the Laplace (time) domain and the mean time to absorption. We also discuss the relaxation to the steady state in the case of confinement with reflecting boundaries and drift effects due to direction-dependent tumbling rates, modeling taxis phenomena of cells. The case of diffusive particles with spatially variable diffusivity is obtained as a limiting case.
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Affiliation(s)
- L Angelani
- ISC-CNR, Institute for Complex Systems, Piazzale Aldo Moro 2, 00185 Rome, Italy.,Dipartimento di Fisica, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Rome, Italy
| | - R Garra
- Dipartimento di Scienze Statistiche, Sapienza Università di Roma, Piazzale Aldo Moro 2, 00185 Rome, Italy
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96
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Dewangan NK, Conrad JC. Rotating oil droplets driven by motile bacteria at interfaces. SOFT MATTER 2019; 15:9368-9375. [PMID: 31693048 DOI: 10.1039/c9sm01570a] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We show that oil droplets suspended near a liquid-solid interface can be driven to rotate by motile bacteria adhered to the droplet surface. Droplets rotate clockwise when viewed from the liquid side, due to symmetry-breaking hydrodynamic interactions of bacteria with the interface. The angular speed of rotation for droplets decreases as their size is increased. Differences in the speed of rotation driven by Escherichia coli, Shewanella haliotis, and Halomonas titanicae bacteria reflects differences in the number of bacteria adhered at the droplet surface and their interfacial affinity. Adding surfactant reduces the number of adherent bacteria and hence lowers the speed of rotation. Together, these results demonstrate that bacterial activity can be used to manipulate suspended droplets.
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Affiliation(s)
- Narendra K Dewangan
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA.
| | - Jacinta C Conrad
- Department of Chemical and Biomolecular Engineering, University of Houston, Houston, TX 77204, USA.
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97
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Dal Cengio S, Levis D, Pagonabarraga I. Linear Response Theory and Green-Kubo Relations for Active Matter. PHYSICAL REVIEW LETTERS 2019; 123:238003. [PMID: 31868450 DOI: 10.1103/physrevlett.123.238003] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Indexed: 05/12/2023]
Abstract
We address the question of how interacting active systems in a nonequilibrium steady state respond to an external perturbation. We establish an extended fluctuation-dissipation theorem for active Brownian particles (ABP), which highlights the role played by the local violation of detailed balance due to activity. By making use of a Markovian approximation we derive closed Green-Kubo expressions for the diffusivity and mobility of ABP and quantify the deviations from the Stokes-Einstein relation. We compute the linear response function to an external force using unperturbed simulations of ABP and compare the results with the analytical predictions of the transport coefficients. Our results show the importance of the interplay between activity and interactions in the departure from equilibrium linear response.
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Affiliation(s)
- Sara Dal Cengio
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
| | - Demian Levis
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
- CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland
- UBICS University of Barcelona Institute of Complex Systems, Martí i Franquès 1, E08028 Barcelona, Spain
| | - Ignacio Pagonabarraga
- Departament de Física de la Matèria Condensada, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
- CECAM Centre Européen de Calcul Atomique et Moléculaire, École Polytechnique Fédérale de Lausanne, Batochime, Avenue Forel 2, 1015 Lausanne, Switzerland
- UBICS University of Barcelona Institute of Complex Systems, Martí i Franquès 1, E08028 Barcelona, Spain
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98
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Basu U, Majumdar SN, Rosso A, Schehr G. Long-time position distribution of an active Brownian particle in two dimensions. Phys Rev E 2019; 100:062116. [PMID: 31962395 DOI: 10.1103/physreve.100.062116] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2019] [Indexed: 06/10/2023]
Abstract
We study the late-time dynamics of a single active Brownian particle in two dimensions with speed v_{0} and rotation diffusion constant D_{R}. We show that at late times t≫D_{R}^{-1}, while the position probability distribution P(x,y,t) in the x-y plane approaches a Gaussian form near its peak describing the typical diffusive fluctuations, it has non-Gaussian tails describing atypical rare fluctuations when sqrt[x^{2}+y^{2}]∼v_{0}t. In this regime, the distribution admits a large deviation form, P(x,y,t)∼exp{-tD_{R}Φ[sqrt[x^{2}+y^{2}]/(v_{0}t)]}, where we compute the rate function Φ(z) analytically and also numerically using an importance sampling method. We show that the rate function Φ(z), encoding the rare fluctuations, still carries the trace of activity even at late times. Another way of detecting activity at late times is to subject the active particle to an external harmonic potential. In this case we show that the stationary distribution P_{stat}(x,y) depends explicitly on the activity parameter D_{R}^{-1} and undergoes a crossover, as D_{R} increases, from a ring shape in the strongly active limit (D_{R}→0) to a Gaussian shape in the strongly passive limit (D_{R}→∞).
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Affiliation(s)
- Urna Basu
- Raman Research Institute, Bengaluru 560080, India
| | - Satya N Majumdar
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Alberto Rosso
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | - Grégory Schehr
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
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99
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Abstract
We propose a generalization of stochastic thermodynamics to systems of active particles, which move under the combined influence of stochastic internal self-propulsions (activity) and a heat bath. The main idea is to consider joint trajectories of particles' positions and self-propulsions. It is then possible to exploit formal similarity of an active system and a system consisting of two subsystems interacting with different heat reservoirs and coupled by a nonsymmetric interaction. The resulting thermodynamic description closely follows the standard stochastic thermodynamics. In particular, total entropy production, Δs_{tot}, can be decomposed into housekeeping, Δs_{hk}, and excess, Δs_{ex}, parts. Both Δs_{tot} and Δs_{hk} satisfy fluctuation theorems. The average rate of the steady-state housekeeping entropy production can be related to the violation of the fluctuation-dissipation theorem via a Harada-Sasa relation. The excess entropy production enters into a Hatano-Sasa-like relation, which leads to a generalized Clausius inequality involving the change of the system's entropy and the excess entropy production. Interestingly, although the evolution of particles' self-propulsions is free and uncoupled from that of their positions, nontrivial steady-state correlations between these variables lead to the nonzero excess dissipation in the reservoir coupled to the self-propulsions.
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Affiliation(s)
- Grzegorz Szamel
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523, USA
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100
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Hermann S, Krinninger P, de Las Heras D, Schmidt M. Phase coexistence of active Brownian particles. Phys Rev E 2019; 100:052604. [PMID: 31869869 DOI: 10.1103/physreve.100.052604] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Indexed: 06/10/2023]
Abstract
We investigate motility-induced phase separation of active Brownian particles, which are modeled as purely repulsive spheres that move due to a constant swim force with freely diffusing orientation. We develop on the basis of power functional concepts an analytical theory for nonequilibrium phase coexistence and interfacial structure. Theoretical predictions are validated against Brownian dynamics computer simulations. We show that the internal one-body force field has four nonequilibrium contributions: (i) isotropic drag and (ii) interfacial drag forces against the forward motion, (iii) a superadiabatic spherical pressure gradient, and (iv) the quiet life gradient force. The intrinsic spherical pressure is balanced by the swim pressure, which arises from the polarization of the free interface. The quiet life force opposes the adiabatic force, which is due to the inhomogeneous density distribution. The balance of quiet life and adiabatic forces determines bulk coexistence via equality of two bulk state functions, which are independent of interfacial contributions. The internal force fields are kinematic functionals which depend on density and current but are independent of external and swim forces, consistent with power functional theory. The phase transition originates from nonequilibrium repulsion, with the agile gas being more repulsive than the quiet liquid.
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Affiliation(s)
- Sophie Hermann
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Philip Krinninger
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Daniel de Las Heras
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
| | - Matthias Schmidt
- Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany
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