We present a model of spike-driven synaptic plasticity inspired by experimental observations and motivated the desire to build an electronic hardware device that can learn classify complex stimuli in semisupervised fashion. During training, patterns activity are sequentially imposed on input neurons, additional instructor signal drives output neurons toward desired activity. The network is made integrate-and-fire with constant leak floor. synapses bistable, they modified arrival presynaptic...

Active colloids exhibit persistent motion, which can lead to motility-induced phase separation (MIPS). However, there currently exists no microscopic theory account for this phenomenon. We report a first-principles theory, free of fit parameters, active spherical colloids, shows explicitly how an effective many-body interaction potential is generated by activity and rationalize MIPS. For passively repulsive system the predicts pair correlations in quantitative agreement with simulation....

We study the phase behaviour and structure of model colloid-polymer mixtures. By integrating out degrees freedom non-adsorbing ideal polymer coils, we derive a formal expression for effective one-component Hamiltonian colloids. Using two-body (Asakura-Oosawa pair potential) approximation to this in computer simulations, determine size ratios q = p/c 0.1, 0.4, 0.6, 0.8, where c p denote diameters colloids respectively. For large q, find both fluid-solid stable fluid-fluid transition. However,...

The mode coupling theory (MCT) of glasses, while offering an incomplete description glass transition physics, represents the only established route to first-principles prediction rheological behavior in nonergodic materials such as colloidal glasses. However, constitutive equations derivable from MCT are somewhat intractable, hindering their practical use and also interpretation. Here, we present a schematic (single-mode) model which incorporates tensorial structure full theory. Using it,...

We investigate the structural, dynamical, and viscoelastic properties of colloid-polymer mixtures at intermediate colloid volume fraction varying polymer concentrations, thereby tuning attractive interactions. Within examined range samples varied from fluids to gels. In liquid phase, an increasing correlation length density fluctuations when approaching gelation boundary was observed by static light scattering microscopy, indicating clustering formation space-spanning networks....

The history dependence of glasses formed from flow-melted steady states by a sudden cessation the shear rate γ[over ˙] is studied in colloidal suspensions, molecular dynamics simulations and mode-coupling theory. In an ideal glass, stresses relax only partially, leaving behind finite persistent residual stress. For intermediate times, relaxation curves scale as function ˙]t, even though no flow present. macroscopic stress evolution connected to length liquefaction displayed microscopic...

Classical density functional theory (DFT) provides an exact variational framework for determining the equilibrium properties of inhomogeneous fluids. We report a generalization DFT to treat non-equilibrium dynamics classical many-body systems subject Brownian dynamics. Our approach is based upon dynamical consisting reversible free energy changes and irreversible power dissipation. Minimization this `free power' with respect microscopic one-body current yields closed equation motion. In...

We present a density functional theory for mixtures of (hard sphere) colloidal particles and ideal polymers. For this extreme nonadditive system we employ fundamental measures approach to construct which incorporates the correct dimensional crossover exact low limit. In bulk fluid yields same free energy and, therefore, gas-liquid (demixing) transition as given by free-volume theory. It generates consistent pair correlation functions; partial structure factors ${S}^{\mathrm{ij}}(k)$ diverge,...

Using a combination of theory, experiment, and simulation we investigate the nonlinear response dense colloidal suspensions to large amplitude oscillatory shear flow. The time-dependent stress is calculated using recently developed schematic mode-coupling-type theory describing under externally applied For finite strain amplitudes generates response, characterized by significant higher harmonic contributions. An important feature prediction an ideal glass transition at sufficiently strong...

Using mode-coupling theory, we derive a constitutive equation for the nonlinear rheology of dense colloidal suspensions under arbitrary time-dependent homogeneous flow. Generalizing previous results simple shear, this allows full tensorial structure theory to be identified. Macroscopic deformation measures, such as Cauchy-Green tensors, thereby emerge. So does direct relation between stress and distorted microstructure, illuminating interplay slow structural relaxation imposed We present...

Colloidal dispersions are commonly encountered in everyday life and represent an important class of complex fluid. Of particular significance for many commercial products industrial processes is the ability to control manipulate macroscopic flow response a dispersion by tuning microscopic interactions between constituents. An step towards attaining this goal development robust theoretical methods predicting from first-principles rheology nonequilibrium microstructure well defined model...

The equations of motion active systems can be modeled in terms Ornstein-Uhlenbeck processes (OUPs) with appropriate correlators. For further theoretical studies, these should approximated to yield a Markovian picture for the dynamics and simplified steady-state condition. We perform comparative study Unified Colored Noise Approximation (UCNA) approximation scheme by Fox recently employed within this context. review approximations necessary define effective interaction potentials low-density...

The escape rate of a Brownian particle over potential barrier is accurately described by the Kramers theory. A quantitative theory explicitly taking activity particles into account has been lacking due to inherently out-of-equilibrium nature these particles. Using an effective equilibrium approach [Farage et al., Phys. Rev. E 91, 042310 (2015)] we study active and compare our analytical results with data from direct numerical simulation colored noise Langevin equation. generates which, when...

We investigate stresses and particle motion during the start-up of flow in a colloidal dispersion close to arrest into glassy state. A combination molecular dynamics simulation, mode-coupling theory confocal microscopy experiments is used origins widely observed stress overshoot (previously not reported) super-diffusive transient dynamics. link between macro-rheological versus strain curves microscopic established. Negative correlations auto-correlation function potential are found...

The question of the existence a structural glass transition in two dimensions is studied using mode coupling theory (MCT). We determine explicit $d$ dependence memory functional for one-component systems. Applied to we solve MCT equations numerically monodisperse hard disks. A dynamic found at critical packing fraction ${\ensuremath{\varphi}}_{c}^{d=2}\ensuremath{\cong}0.697$ which above ${\ensuremath{\varphi}}_{c}^{d=3}\ensuremath{\cong}0.516$ by about 35%. ${\ensuremath{\varphi}}_{c}^{d}$...

A space-dependent Lorentz force causes a flux and an inhomogeneous density in system of active Brownian particles. The is induced by the gradient alone does not require additional symmetry breaking

A recent density functional theory is used to investigate the free interface between demixed fluid phases in a model colloid-polymer mixture. Both colloid and polymer profiles oscillate on colloid-rich side of interface, provided reservoir packing fraction ηpr sufficiently high. Results for surface tension are reasonable agreement with experiment. When mixture adsorbed against hard wall, entropic depletion effects give rise wetting transition whereby phase wets completely. Prior complete we...

We describe two strategies for tackling the equilibrium statistical mechanics of inhomogeneous colloid—polymer mixtures treated in terms simple Asakura—Oosawa—Vrij (AO) model, which colloid—colloid and interactions are hard-sphere like, whereas polymer—polymer interaction is zero (perfectly interpenetrating polymer spheres). The first strategy based upon integrating out degrees freedom spheres to obtain an effective one-component Hamiltonian colloids. This particularly small size ratios q =...

We describe a density functional theory for mixtures of hard sphere (HS) colloids and ideal polymers, the Asakura–Oosawa model. The geometry-based fundamental measures approach which is used to construct ensures correct behaviour in limit low both species zero-dimensional cavity can contain at most one HS. Dimensional crossover discussed detail. Emphasis placed on properties homogeneous (bulk) fluid phases. show that present yields same free energy and, therefore, fluid–fluid demixing...

We consider the nonlinear rheology of dense colloidal suspensions under a time-dependent simple shear flow. Starting from Smoluchowski equation for interacting Brownian particles advected by shearing (ignoring fluctuations in fluid velocity), we develop formalism which enables calculation time-dependent, far-from-equilibrium averages. Taking stress as an example, derive exactly generalized Green-Kubo relation and motion transient density correlator, involving three-time memory function. Mode...

Using a dynamical density functional theory we analyse the profile of colloidal liquid near wall under shear flow. Due to symmetries system considered, naive application does not lead induced modification equilibrium profile, which would be expected on physical grounds. By introducing physically motivated dynamic mean field correction incorporate missing interparticle forces into theory. We find that flow tends enhance oscillations in hard spheres at and, sufficiently high rates, induces...

A simple theoretical approach is used to investigate active colloids at the free interface and near repulsive substrates. We employ dynamical density functional theory determine steady-state profiles in an effective equilibrium system [Farage et al., Phys. Rev. E, 91 (2015) 042310]. In addition known accumulation surfaces, we predict wetting drying transitions a flat wall capillary condensation evaporation slit pore. These new phenomena are closely related motility-induced phase separation...

Theoretical approaches to nonequilibrium many-body dynamics generally rest upon an adiabatic assumption, whereby the true is represented as a sequence of equilibrium states. Going beyond this simple approximation notoriously difficult problem. For case classical Brownian dynamics, we present simulation method that allows us isolate and precisely evaluate superadiabatic correlations resulting forces. Application system one-dimensional hard particles reveals importance for well complexity,...

Active particles driven by colored noise can be approximately mapped onto a system that obeys detailed balance. The effective interactions which derived for such allow to describe the structure and phase behavior of active fluid means an free energy. In this paper we explain why related thermodynamic results pressure interfacial tension do not represent one would measure mechanically. We derive dynamical density functional theory, in steady state simultaneously validates use provides access...

We generalize the Green-Kubo approach, previously applied to bulk systems of spherically symmetric active particles [J. Chem. Phys. 145, 161101 (2016)JCPSA60021-960610.1063/1.4966153], include spatially inhomogeneous activity. The method is predict spatial dependence average orientation per particle and density. given by an integral over self part Van Hove function a simple Gaussian approximation this quantity yields accurate analytical expression. Taking result as input dynamic density...