A complete and detailed knowledge of the structure of the gaseous component in protoplanetary discs is essential to the study of dust evolution during the early phases of pre-planetesimal formation. The aim of this paper is to determine if three-dimensional accretion discs simulated by the Smoothed Particle Hydrodynamics (SPH) method can reproduce the observational data now available and the ex...

The viscosity of glass formers increases by several orders of magnitude upon cooling near the glass transition temperature. For strong glass formers, this increase is Arrhenius-like, that is, the viscosity increases exponentially with inverse temperature, whereas, for fragile glass formers, this increase is super-Arrhenius-like. Recent experimental and theoretical evidence indicates that fragil...

The empirical concept of internal friction was introduced 20 years ago. This review summarizes the results of experimental and theoretical studies that help to uncover the nature of internal friction. After the history of the concept, we describe the experimental challenges in measuring and interpreting internal friction based on the viscosity dependence of enzyme reactions. We also present spe...

The Shape–from–Shading models in image analysis lead to first order Hamilton– Jacobi equations which may have several weak solutions (in the viscosity sense). Moreover, for real images, these equations are highly discontinuous in the space variable. The lack of uniqueness and the irregularity of the coefficients involve some troubles when we try to compute a solution. In order to avoid these di...

Viscosity has been determined during isothermal crystallization of an andesite from Tungurahua volcano (Ecuador). Viscosity was continuously recorded using the concentric cylinder method and employing a Pt-sheathed alumina spindle at 1 bar and from 1400°C to subliquidus temperatures to track rheological changes during crystallization. The disposable spindle was not extracted from the sample but...

The effect of extensional flow on apparent shear viscosity has never previously been directly measured nor is it often considered. Here, for the first time, through using a novel configuration (two-phase response under flow), we have viscoelastic polymer solution in controlled and kinematically mixed manner. We show, via control transient experiment, that deformation depends not only rate but a...