Inspired by the Turing mechanism for pattern formation, we propose a simple self-propelled particle model with short-range alignment and antialignment at larger distances. It is able to produce orientationally ordered states, periodic vortex patterns, mesoscale turbulence, which resembles observations in dense suspensions of swimming bacteria. The allows systematic derivation analysis kinetic theory as well hydrodynamic equations density momentum fields. A phase diagram regions formation...

A wide range of experimental systems including gliding, swarming and swimming bacteria, in-vitro motility assays as well shaken granular media are commonly described self-propelled rods. Large ensembles those entities display a large variety self-organized, collective phenomena, formation moving polar clusters, nematic dynamic bands, mobility-induced phase separation, topological defects mesoscale turbulence, among others. Here, we give brief survey observations review the theoretical...

We study the dynamics of micron-sized particles on a layer motile cells. This cell carpet acts as an active bath that propels passive tracer via direct mechanical contact. The resulting nonequilibrium transport shows crossover from superdiffusive to normal-diffusive dynamics. particle displacement distribution is distinctly non-Gaussian even at macroscopic timescales exceeding measurement time. obtain diffusion coefficients experimental data and introduce model for matches experimentally...

Bacteria swim in sequences of straight runs that are interrupted by turning events. They drive their swimming locomotion with the help rotating helical flagella. Depending on number flagella and arrangement across cell body, different run-and-turn patterns can be observed. Here, we present fluorescence microscopy recordings showing cells soil bacterium Pseudomonas putida decorated a polar tuft flagella, alternate between two distinct patterns. On one hand, they undergo classical...

Bacterial chemotaxis-a fundamental example of directional navigation in the living world-is key to many biological processes, including spreading bacterial infections. Many species were recently reported exhibit several distinct swimming modes-the flagella may, for example, push cell body or wrap around it. How do different run modes shape chemotaxis strategy a multimode swimmer? Here, we investigate chemotactic motion soil bacterium Pseudomonas putida as model organism. By simultaneously...

We consider a model of active Brownian particles (ABPs) with velocity alignment in two spatial dimensions passive and fluctuations. Here, fluctuations refers to purely non-equilibrium stochastic forces correlated the heading an individual particle. In simplest case studied here, they are assumed be independent parallel (speed noise) perpendicular (angular On other hand, defined by noise vector direction motion particle, may account, for example, thermal derive macroscopic description ABP gas...

In this work we derive and analyse coarse-grained descriptions of self-propelled particles with selective attraction–repulsion interaction, where individuals may respond differently to their neighbours depending on relative state motion (approach versus movement away). Based the formulation a nonlinear Fokker–Planck equation, kinetic description system dynamics in terms equations for Fourier modes one-particle density function. This approach allows effective numerical investigation stability...

The diffusion properties of self-propelled particles which move at constant speed and, in addition, reverse their direction motion repeatedly are investigated. internal dynamics triggering these reversal processes is modeled by a stochastic clock. velocity correlation function as well the mean squared displacement investigated furthermore, general expression for coefficient with directional derived. Our analysis reveals existence an optimal, finite rotational noise amplitude maximizes...

We study self-propelled particles with velocity reversal interacting by uniaxial (nematic) alignment within a coarse-grained hydrodynamic theory. Combining analytical and numerical continuation techniques, we show that the physics of this active system is essentially controlled frequency. In particular, find elongated, high-density, ordered patterns, called bands, emerge via subcritical bifurcations from spatially homogeneous states. Our analysis reveals further interaction bands weakly...

Active matter research focuses on the emergent behavior among interacting self-propelled particles. Unification of seemingly disconnected paradigms -- active phase-separation repulsive discs and collective motion rods is a major challenge in contemporary matter. Inspired by quanto-mechanical wave-particle duality, we develop an approach based representation particles smoothed continuum fields. On basis collision kinetics, demonstrate analytically numerically how nonequilibrium stresses...

We study an ensemble of random walkers carrying internal noisy phase oscillators which are synchronized among the by local interactions. Due to individual mobility, interaction partners every walker change randomly, hereby introducing additional, independent source fluctuations, thus constituting intrinsic nonequilibrium nature temporal dynamics. employ this paradigmatic model system discuss how emergence order is affected motion entities. In particular, we consider both normal diffusive and...

Motivated by various recent experimental findings, we propose a dynamical model of intermittently self-propelled particles: active particles that recurrently switch between two modes motion, namely an run-state and turn state, in which self-propulsion is absent. The durations these motility are derived from arbitrary waiting-time distributions. We derive the expressions for exact forms transport characteristics like mean-square displacements diffusion coefficients to describe such processes....

While bacterial swimming has been well characterized in uniform liquid environments, only little is known about how bacteria propagate through complex such as gel-like matrices or porous media that are typically encountered tissue soil. Here, we study motility of the soil bacterium Pseudomonas putida (P. putida) polysaccharide formed by different concentrations agar. P. cells display intermittent run-motility gel, where run times exponentially distributed and intermittently occurring dwell...

We explore minimal navigation strategies for active particles in complex, dynamical, external fields, introducing a class of autonomous, self-propelled which we call Markovian robots (MR). These machines are equipped with control system (NCS) that triggers random changes the direction self-propulsion robots. The internal state NCS is described by Boolean variable adopts two values. temporal dynamics this dictated closed Markov chain -- ensuring absence fixed points transition rates may...

Flow control is a highly relevant topic for micromanipulation of colloidal particles in microfluidic applications. Here, we report on system that combines two-surface bound flows emanating from thermo-osmotic and diffusio-osmotic mechanisms. These opposing are generated at gold surface immersed into an aqueous solution containing photo-sensitive surfactant, which irradiated by focused UV laser beam. At low power incoming light, flow due to local photo-isomerization the surfactant dominates,...

The coupling of the internal mechanisms cell polarization to shape deformations and subsequent crawling poses many interdisciplinary scientific challenges. Several mathematical approaches have been proposed model both processes, where one most successful methods relies on a phase field that encodes morphology cell, together with integration partial differential equations account for mechanism inside domain as defined by field. This approach has previously employed motion single cells social...

Abstract The integration of motile cells into biohybrid microrobots offers unique properties such as sensitive responses to external stimuli, resilience, and intrinsic energy supply. Here, cell–cargo systems that are driven by amoeboid Dictyostelium discoideum studied how the cargo speed resulting viscous drag force scales with increasing radius spherical particle explored. Using a simplified geometrical model interaction, findings toward larger sizes, which not accessible experimental...

As society paves its way towards device miniaturization and precision medicine, microscale actuation transport become increasingly prominent research fields with high impact in both technological clinical contexts. In order to accomplish movement of micron-sized objects specific target sites, active biohybrid systems, such as motile living cells that act smart biochemically powered microcarriers, have been suggested an alternative synthetic microrobots. Inspired by the motility leukocytes,...

Motivated by the observation of non-exponential run-time distributions bacterial swimmers, we propose a minimal phenomenological model for taxis active particles whose motion is controlled an internal clock. The ticking clock depends on external concentration field, e.g., chemical substance. We demonstrate that these can detect gradients and respond to them moving up- or down-gradient depending design, albeit measurements fields are purely local in space instantaneous time. Altogether, our...