The attenuation coefficient and phase velocity of plane sound waves propagating in three perpendicular directions in glass wool were measured in the frequency range 50-10,000 Hz. For glass wool of mass density 14 kg/m3 at the frequency 1,000 Hz, the attenuation constant for propagation perpendicular to the glass wool sheets was 75 dB/m, and for propagation parallel with the sheets 57 dB/m. For ...

The computed tomographic (CT) densities of imaged structures are a function of the CT scanning protocol, the structure size, and the structure density. For objects that are of a dimension similar to the scanner point spread function, CT will underestimate true structure density. Prior investigation suggests that this process, termed contrast reduction, could be used to estimate the strength of ...

Hypertension and atherogenic low-density lipoproteins cause attenuation of endothelium-dependent dilations in vivo. We investigated a potential interference of high transmural pressure with the effects of low-density lipoproteins on endothelium-dependent dilation in vitro. Furthermore, we determined whether high-density lipoproteins preserve endothelial function. Endothelium-intact rabbit renal...

Mangrove forests cover the upper intertidal zones of tropical and subtropical shorelines. They play an important part in ecological, economical, physical, biological, chemical geomorphological aspects. In Malaysia there are several small rivers estuaries which frequented by fishing boats. The present study deals with physical processes involved dissipation waves from boat wakes roots mangrove v...

introduction: the main goal of spect imaging is to determine activity distribution inside the organs of the body. however, due to photon attenuation, it is almost impossible to do a quantitative study. in this paper, we suggest a mathematical relationship between activity distribution and its corresponding projections using a transfer matrix. monte carlo simulation was used to find a precise tr...

The effects of seagrass bed geometry on wave attenuation and suspended sediment transport were investigated using a modified Nearshore Community Model (NearCoM). The model was enhanced to account for cohesive sediment erosion and deposition, sediment transport, combined wave and current shear stresses, and seagrass effects on drag. Expressions for seagrass drag as a function of seagrass shoot d...

Third sound attenuation in thick He films has been observed to be much greater than predictions based on known mechanisms. We propose a possible mechanism for this observed high attenuation. Pinned vortices, possibly created when the superfluid transition is traversed, undergo driven oscillations in the third sound wave flow field. The dissipation is caused by two related effects. The first is ...

Generally, computerised tomography (CT) is an X-ray based non-destructive testing method that was developed for medical purposes in the seventies and introduced for industrial applications during the eighties. CT produces maps of the X-ray linear attenuation coefficient of an object’s interior; presented either as cross section images (two-dimensional CT) or as volume information (three-dimensi...