Improving acoustic wave propagation models in highly attenuating porous materials.

This article presents an improved and extended modeling approach for acoustic wave propagation in rigid porous materials, focusing on examples, such as plastic foams used for noise reduction in automotive applications. We demonstrate that the classical model (Johnson-Champoux-Allard) in the asymptotic high-frequency limit, widely employed in the literature, fails to accurately reconstruct the transmitted acoustic signal through high absorbent porous materials characterized by significant wave attenuation. The study focuses on the airborne ultrasonic frequency range (30-200 kHz).

Growth with Commensal Streptococci Alters Behaviors.

As oral bacteria grow and persist within biofilms attached to the tooth's surface, they interact with other species to form synergistic or antagonistic exchanges that govern homeostasis for the overall population. One example are the interactions between the cariogenic species and oral commensal streptococci. Previously, we showed that the cell-cell signaling pathways of were inhibited during coculture with other oral streptococci species, leading us to posit that the transcriptome and behaviors are broadly altered during growth with these species.

Fractal Analysis of a Non-Newtonian Fluid Flow in a Rough-Walled Pipe.

The fully developed laminar flow of a viscous non-Newtonian fluid in a rough-walled pipe is considered. The fluid rheology is described by the power-law model (covering shear thinning, Newtonian, and shear thickening fluids). The rough surface of the pipe is considered to be fractal, and the surface roughness is measured using surface fractal dimensions.