We study experimentally and numerically the dynamics of colloidal beads confined by a harmonic potential in bath swimming E. coli bacteria. The resulting is well approximated Langevin equation for an overdamped oscillator driven combination white thermal noise exponentially correlated active noise. This scenario leads to simple generalization equipartition theorem coexistence two different effective temperatures that govern along flat curved directions landscape.

Collective cell migration in dense tissues underlies important biological processes, such as embryonic development, wound healing and cancer invasion. While many aspects of single movements are now well established, the mechanisms leading to displacements cohesive groups still poorly understood. To elucidate emergence collective mechanosensitive cells, we examine a self-propelled Voronoi (SPV) model confluent with an orientational feedback that aligns cell's polarization its local velocity....

We investigate experimentally and numerically the stochastic dynamics time-dependent response of colloids subject to a small external perturbation in dense bath motile E. coli bacteria. The field is magnetic acting on superparamagnetic microbead suspended an active medium. measured linear reveals instantaneous friction kernel despite complexity bacterial bath. By comparing mean squared displacement function we detect clear violation fluctuation dissipation theorem.

The present paper studies the spontaneous velocity alignment and time-intermittency of kinetic-energy in dense phases active matter. dynamical properties are described by considering spatial correlations constructing a non-equilibrium phase diagram force density which explores homogeneous inhomogeneous

Abstract Dense active systems are widespread in nature, examples range from bacterial colonies to biological tissues. clusters of particles can be obtained by increasing the packing fraction system or taking advantage a peculiar phenomenon named motility-induced phase separation (MIPS). In this work, we explore diagram two-dimensional model glass and show that disordered materials develop rich collective behaviour encompassing both MIPS glassiness. We find that, although glassy state is...

We investigate numerically the dynamics of shape and displacement fluctuations two-dimensional flexible vesicles filled with active particles. At low concentration most particles accumulate at boundary vesicle where positive particle number are amplified by trapping, leading to formation pinched spots high density, curvature pressure. cover almost uniformly, resulting in fairly homogeneous pressure curvature, nearly circular shape. The change between polarized spherical shapes is driven...

Abstract We derive an analytic expression for the distribution of velocities multiple interacting active particles which we test by numerical simulations. In clear contrast with equilibrium find that are coupled to positions. Our model shows that, even two only, individual display a variance depending on interparticle separation and emergence correlations between particles. When considering systems composed many connecting overall velocity density, at mean-field level, pair function valid in...

Performing large-scale simulations of active particles and employing finite-size-scaling analysis, we provide exhaustive evidence that motility-induced critical point belongs to the Ising universality class.

Abstract The frequency scaling exponent of low-frequency excitations in microscopically small glasses, which do not allow for the existence waves (phonons), has been focus recent literature. density states g ( ω ) these modes obeys an s scaling, where , ranging between 2 and 5, depends on quenching protocol. orgin findings remains controversal. Here we show, using heterogeneous-elasticity theory, that a marginally-stable glass sample follows Debye-like = 2), associated (type-I) are...

Significance Amorphous solids are continuum media. However, their mechanical and thermodynamical properties, even though universal, dramatically deviate from those in crystalline solids. Their anomalous behavior reflects peculiar universal deviations Debye’s law the low-frequency sector of density states <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>D</mml:mi> <mml:mrow> <mml:mo>(</mml:mo> <mml:mi>ω</mml:mi> </mml:mrow> <mml:mo>)</mml:mo> </mml:math> ....

This work studies the dynamics of inertial active particles under strong confinement and observe that he probability density position peaks at a finite distance away from confining wall, individual exhibit several dynamical states transitions between them can be controlled by level self-propulsion.

Abstract Living materials such as biological tissues or bacterial colonies are collections of heterogeneous entities different sizes, capable autonomous motion, and often cooperating. Such a degree complexity brings to collective motion on large scales. However, how the competition between geometrical frustration, tendency move cooperatively impact large-scale behavior remains an open question. We implement those three ingredients in model active matter show that system, forming migratory...

In order to understand the mechanisms for glassy dynamics in biological tissues and shed light on those non-biological materials, we study low-temperature disordered phase of 2D vertex-like models.Recently it has been noted that vertex models have quite unusual behavior zero-temperature limit, with rigidity transitions are controlled by residual stresses therefore exhibit very different scaling phenomenology compared particulate systems.Here investigate finite-temperature two-dimensional...

We numerically investigate the correlation function, response and breakdown of Fluctuation-Dissipation Theorem (FDT) in active particles close to motility-induced critical point. find a strong FDT violation short time wavelength regime, where function has larger amplitude than fluctuation spectrum. Conversely, at spatiotemporal scales, is restored slowing-down compatible with Ising universality class. Building on these results, we develop novel field-theoretical description employing...

Spreading processes on top of active dynamics provide a novel theoretical framework for capturing emerging collective behavior in living systems. I consider run-and-tumble coupled with coagulation/decoagulation reactions that lead to an absorbing state phase transition. While the does not change location transition point, relaxation toward stationary depends motility parameters. Because competition between spreading and motion, system can support long-living currents whose typical time scale...

We numerically study the dynamics of run-and-tumble particles confined in two chambers connected by thin channels. Two dominant dynamical behaviors emerge: (i) an oscillatory pumping state, which periodically fill vessels and (ii) a circulating flow dynamically maintaining near constant population level containers when demonstrate that behaviour arises from combination narrow channel, preventing bacteria reorientation, density dependent motility inside chambers.

We investigate the effect of self-propulsion on a mean-field order-disorder transition. Starting from ${\ensuremath{\varphi}}^{4}$ scalar field theory subject to an exponentially correlated noise, we exploit unified colored-noise approximation map nonequilibrium active dynamics onto effective equilibrium one. This allows us follow evolution second-order critical point as function noise parameters: correlation time $\ensuremath{\tau}$ and strength $D$. Our results suggest that universality...

We consider the pressure in steady-state regime of three stochastic models characterized by self-propulsion and persistent motion widely employed to describe behavior active particles, namely, Active Brownian particle (ABP) model, Gaussian colored noise (GCN) unified approximation (UCNA) model. Whereas limit short but finite persistence time, UCNA model can be obtained different methods which have an analog equilibrium systems, remaining two only virial route is, general, possible. According...

We examine the interplay of motility and information exchange in a model active particles. Non-motile particles additionally recover their at fixed rate, as SIS (Susceptible, Infected, Susceptible) epidemic spreading.

Using the path integral representation of nonequilibrium dynamics, we compute most probable between arbitrary starting and final points that is followed by an active particle driven persistent noise. We focus our attention on case particles immersed in harmonic potentials, where trajectory can be computed analytically. Once consider extended Markovian dynamics self-propulsive drive evolves according to Ornstein-Uhlenbeck process, analytically with conditions position self-propulsion...

We investigate the steady state properties of an active fluid modeled as assembly soft repulsive spheres subjected to Gaussian colored noise. Such a noise captures one salient aspects particles, namely persistence their motion and determines variety novel features with respect familiar passive fluids. show that within so-called multidimensional unified approximation, recently introduced in field matter, model can be treated by methods similar those employed study standard molecular The...

In active φ^{4} field theories the nonequilibrium terms play an important role in describing phase separation; however, they are irrelevant, renormalization group sense, at critical point. Their irrelevance makes exponents same as those of Ising universality class. Despite their irrelevance, contribute to a nontrivial scaling entropy production rate criticality. We consider dynamics nonconserved scalar φ (Model A) driven out-of-equilibrium by persistent noise that is correlated on finite...

As wounds heal, embryos develop, cancer spreads, or asthma progresses, the cellular monolayer undergoes glass transition between solid-like jammed and fluid-like flowing states. During some of these processes, cells undergo an epithelial-to-mesenchymal (EMT): they acquire in-plane polarity become motile. Thus, how motility drives glassy dynamics in epithelial systems is critical for EMT process. However, no analytical framework that indispensable deeper insights exists. Here, we develop such...