Space-time Phase Transitions in Driven Kinetically Constrained Lattice Models

Kinetically constrained models (KCMs) have been used to study and understand the origin of glassy dynamics. Despite having trivial thermodynamic properties, their dynamics slows down dramatically at low temperatures while displaying dynamical heterogeneity as seen in glass forming supercooled liquids. This dynamics has its origin in an ergodic-nonergodic first-order phase transition between phases of distinct dynamical "activity". This is a "space-time" transition as it corresponds to a singular change in ensembles of trajectories of the dynamics rather than ensembles of configurations. Here we extend these ideas to driven glassy systems by considering KCMs driven into non-equilibrium steady states through non-conservative forces. By classifying trajectories through their entropy production we prove that driven KCMs also display an analogous first-order space-time transition between dynamical phases of finite and vanishing entropy production. We also discuss how trajectories with rare values of entropy production can be realized as typical trajectories of a mapped system with modified forces

Phase separation in star polymer-colloid mixtures

We examine the demixing transition in star polymer-colloid mixtures for star arm numbers f=2,6,16,32 and different star-colloid size ratios. Theoretically, we solve the thermodynamically self-consistent Rogers-Young integral equations for binary mixtures using three effective pair potentials obtained from direct molecular computer simulations. The numerical results show a spinodal instability. The demixing binodals are approximately calculated, and found to be consistent with experimental observations.Comment: 4 pages, 4 figures, submitted to PR

Glasses in hard spheres with short-range attraction

We report a detailed experimental study of the structure and dynamics of glassy states in hard spheres with short-range attraction. The system is a suspension of nearly-hard-sphere colloidal particles and non-adsorbing linear polymer which induces a depletion attraction between the particles. Observation of crystallization reveals a re-entrant glass transition. Static light scattering shows a continuous change in the static structure factors upon increasing attraction. Dynamic light scattering results, which cover 11 orders of magnitude in time, are consistent with the existence of two distinct kinds of glasses, those dominated by inter-particle repulsion and caging, and those dominated by attraction. Samples close to the `A3 point' predicted by mode coupling theory for such systems show very slow, logarithmic dynamics.Comment: 22 pages, 18 figure

Macromolecular theory of solvation and structure in mixtures of colloids and polymers

The structural and thermodynamic properties of mixtures of colloidal spheres and non-adsorbing polymer chains are studied within a novel general two-component macromolecular liquid state approach applicable for all size asymmetry ratios. The dilute limits, when one of the components is at infinite dilution but the other concentrated, are presented and compared to field theory and models which replace polymer coils with spheres. Whereas the derived analytical results compare well, qualitatively and quantitatively, with mean-field scaling laws where available, important differences from ``effective sphere'' approaches are found for large polymer sizes or semi-dilute concentrations.Comment: 23 pages, 10 figure

Constructivist learning theories and complex learning environments

Contains fulltext : 64031.pdf (publisher's version ) (Open Access

Modeling work-related learning on the basis of intentionality and developmental relatedness: A non-educational perspective

Contains fulltext : 64800_pub.pdf (publisher's version ) (Open Access) Contains fulltext : 64800_aut.pdf (author's version ) (Open Access

Leerstrategieën, leren en verantwoordelijkheid

De oratie is opgebouwd in drie hoofdstukken. Onder 'Leren en onderwijs' wordt betoogd waarom het onderwijs moet uitgaan van een bredere visie op leren, inclusief leerstrategieën. Daarbij wordt de relatie tussen kennis en leren besproken en de vele manieren waarom mensen in hun leven leren. Onder 'Kerntaak van het onderwijs' gaat het om de belangrijke verantwoordelijkheid van onderwijs in het handhaven en steeds opnieuw vormgeven van een open, democratische en humane samenleving. Onder 'Thema's bij het opleiden van leraren' wordt, vanuit het principe van congruentie ('walk the talk'), een aantal belangrijke onderwerpen bij het opleiden van leraren besproken. Ook uitgegeven door Coutinho, Bussum. ISBN 90 6283 454 X; www.coutinho.n

Leren en veranderen bij volwassenen. Een nieuwe benadering

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