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Presentation of Acoustic Waves Propagation and Their Effects Through Human Body Tissues

100%

Tsaklis P.

Human Movement

2010

vol. 11

issue 1

58-65

Three types of acoustic waves are mainly used in the medical field, Extracorporeal Shock Waves (ESWs), Pressure Waves (PWs) and Ultrasound (US). Shock waves are acoustic waves that are characterized by high pressure amplitudes and an abrupt increase in pressure that propagates rapidly through a medium. The energy distribution in the treatment area differs from being wide over a large area, or concentrated in a narrow treatment zone, and as such influences the therapeutic and biological effect of the shock wave. Pressure waves are usually generated by the collision of solid bodies with an impact speed of a few metres per second, far below the speed the shock wave travels. There are major differences between PWs and ESWs, concerning not only their physical characteristics and the technique used for generating them, but also the order of the parameters normally used. The simulation effects and therapeutic mechanisms seem to be similar, despite the physical differences and the resulting different application areas (on the surface and in depth respectively). Ultrasound therapy is one of the modalities of physical medicine used for pain management and for increasing blood flow and mobility. Ultrasound and ESWs - PWs differ, despite their acoustic relationship, basically because ESWs - PWs show large pressure amplitudes with direct mechanical effects and US propagates within periodic oscillations within a limited bandwidth, and mainly direct thermal effects. Acoustic waves have direct mechanical and mechanotransduction effects on the cells and ECM increasing porosity, angiogenesis, releasing growth factors, enhancing proteosynthesis and viscoelastisity and inducing histeogenesis and repair processes.

Generation of shock waves in dense plasmas by high-intensity laser pulses

86%

Pasley J., Bush I. A., Robinson A. P. L., Rajeev P. P., Mondal S., Lad A. D., Ahmed S., Narayanan V., Kumar G. R., Kingham R. J.

Nukleonika

2015

vol. 60

issue 2

193-198

When intense short-pulse laser beams (I > 1022 W/m2, τ < 20 ps) interact with high density plasmas, strong shock waves are launched. These shock waves may be generated by a range of processes, and the relative significance of the various mechanisms driving the formation of these shock waves is not well understood. It is challenging to obtain experimental data on shock waves near the focus of such intense laser–plasma interactions. The hydrodynamics of such interactions is, however, of great importance to fast ignition based inertial confinement fusion schemes as it places limits upon the time available for depositing energy in the compressed fuel, and thereby directly affects the laser requirements. In this manuscript we present the results of magnetohydrodynamic simulations showing the formation of shock waves under such conditions, driven by the j × B force and the thermal pressure gradient (where j is the current density and B the magnetic field strength). The time it takes for shock waves to form is evaluated over a wide range of material and current densities. It is shown that the formation of intense relativistic electron current driven shock waves and other related hydrodynamic phenomena may be expected over time scales of relevance to intense laser–plasma experiments and the fast ignition approach to inertial confinement fusion. A newly emerging technique for studying such interactions is also discussed. This approach is based upon Doppler spectroscopy and offers promise for investigating early time shock wave hydrodynamics launched by intense laser pulses.

Magnetoacoustic Heating of Plasma Caused by Periodic Magnetosound Perturbations with Discontinuities in a Quasi-Isentropic Magnetic Gas

86%

Perelomova A., Perelomova A.

Archives of Acoustics

2020

vol. 45

issue 2

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1 Archives of Acoustics

1 Human Movement

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1 Ahmed S.

1 Bush I. A.

1 Kingham R. J.

1 Kumar G. R.

1 Lad A. D.

1 Mondal S.

1 Narayanan V.

1 Pasley J.

1 Perelomova A.

1 Rajeev P. P.

1 Robinson A. P. L.

1 Tsaklis P.

Search results

Presentation of Acoustic Waves Propagation and Their Effects Through Human Body Tissues

Generation of shock waves in dense plasmas by high-intensity laser pulses

Magnetoacoustic Heating of Plasma Caused by Periodic Magnetosound Perturbations with Discontinuities in a Quasi-Isentropic Magnetic Gas