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A mathematical form is proposed for the study of the problem of reflection-transmission of monochromatic ultrasonic plane waves at the interface between two arbitrary anisotropic semiinfinite media. The method used leads to a complete determination of all characteristics of the studied waves for all possible configurations, i.e., their directions of propagation, polarizations, and magnitudes. In particular, cases are taken into account where the waves generated by the existence of the interface are evanescent or more generally inhomogeneous. Applying this method to the calculation of several practical cases typically encountered in ultrasonic nondestructive evaluation fields, this paper points out the existence of phenomena that cannot be interpreted by classical methods usually used for the resolution of this kind of problem.

In this work we studied the diffusive behavior of active brownian particles under lateral parabolic confinement. The results showed that we go from subdiffusion to ballistic motion as we vary the angular noise strength and confinement intensity. We argued that the subdiffusion regimes appear as consequence of the restricted space available for diffusion (achieved either through large confinement and/or large noise); we saw that when there are large confinement and noise intensity, a similar configuration to single file diffusion appears; on the other hand, normal and superdiffusive regimes may occur due to low noise (longer persistent motion), either through exploring a wider region around the potential minimum in the transverse direction (low confinement), or by forming independent clusters (high confinement).

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