Particles in dusty plasmas are often confined to a quasi-two-dimensional arrangement. In such layers--besides the formation of compressional and (in-plane) shear waves--an additional collective excitation may also show up, as small-amplitude oscillations of the particles perpendicular to the plane are also possible. We explore through molecular dynamics simulations the properties (fluctuation s...

S U M M A R Y We present a derivation of the equations describing wave propagation in porous media based upon an averaging technique which accommodates the transition from the microscopic to the macroscopic scale. We demonstrate that the governing macroscopic equations determined by Biot remain valid for media with gradients in porosity. In such media, the well-known expression for the change i...

The elasticity of high-pressure mantle phases may be characterized by crystal chemically similar compounds. Analogue compounds available as single crystals yield the most reliable elastic constant data. The single-crystal elastic constants of pleonaste and hercynite spinel, rutile-structure germanium dioxide, and spessartite-almandine garnet are studied, in most cases as a function of pressure ...

Anisotropy in physical properties of rocks can arise from preferred mineral orientation, mineral layering, nonhydrostatic stress, and anisotropic crack distribution. For instance, all of the following cause acoustic double refraction: preferential orientation of olivine grains in dunites, alternating layers in laboratory-sizedsamples of such mineral pairs as olivine-feldspar, wollastonite-diops...

Stress-strain measurements and ultrasound propagation experiments in glass bead packs have been simultaneously conducted to characterize the stress-induced anisotropy under uniaxial loading. These measurements realized, respectively, with finite and incremental deformations of the granular assembly, are analyzed within the framework of the effective-medium theory based on the Hertz-Mindlin cont...