Compact Expansion of a Repulsive Suspension.

Short-range repulsion governs the dynamics of matter from atoms to animals. Using theory, simulations, and experiments, we find that an ensemble of repulsive particles spreads compactly with a sharp boundary, in contrast to the diffusive spreading of Brownian particles. Starting from the pair interactions, at high densities, the many-body dynamics follow nonlinear diffusion with a self-similar expansion, growing as t^{1/4}; At longer times, thermal motion dominates with the classic t^{1/2} expansion.

Are reduced fetal movements "merely" a maternal perception or truly a reflection of umbilical cord complications? A clinical trial.

Objective: To characterize obstetric outcomes and the association with umbilical cord (UC) complications among women complaining of reduced fetal movements (RFMs).

Methods: This retrospective cohort compared women with a perception of RFMs within 2 weeks prior to delivery with women who reported no changes in fetal movements in terms of maternal characteristics and neonatal outcomes. A primary outcome of UC complications at delivery was defined.

Reconfiguration, Interrupted Aging, and Enhanced Dynamics of a Colloidal Gel Using Photoswitchable Active Doping.

We study quasi-2D gels made of a colloidal network doped with Janus particles activated by light. Following the gel formation, we monitor both the structure and dynamics before, during, and after the activation period. Before activity is switched on, the gel is slowly aging.

Hydrodynamic spin-orbit coupling in asynchronous optically driven micro-rotors.

Vortical flows of rotating particles describe interactions ranging from molecular machines to atmospheric dynamics. Yet to date, direct observation of the hydrodynamic coupling between artificial micro-rotors has been restricted by the details of the chosen drive, either through synchronization (using external magnetic fields) or confinement (using optical tweezers). Here we present a new active system that illuminates the interplay of rotation and translation in free rotors.