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Ultrasound is sound with frequencies greater than 20 kilohertz. [1] This frequency is the approximate upper audible limit of human hearing in healthy young adults. The physical principles of acoustic waves apply to any frequency range, including ultrasound.
Ultrasound energy, simply known as ultrasound, is a type of mechanical energy called sound characterized by vibrating or moving particles within a medium. Ultrasound is distinguished by vibrations with a frequency greater than 20,000 Hz, compared to audible sounds that humans typically hear with frequencies between 20 and 20,000 Hz.
Medical ultrasound includes diagnostic techniques (mainly imaging techniques) using ultrasound, as well as therapeutic applications of ultrasound. In diagnosis, it is used to create an image of internal body structures such as tendons, muscles, joints, blood vessels, and internal organs, to measure some characteristics (e.g., distances and velocities) or to generate an informative audible sound.
Typical diagnostic ultrasound machines operate in the frequency range of 2-18 megahertz, whereas home ultrasound machines and therapeutic ultrasound machines operate in the frequency range of .7-3.3 megahertz. Diagnostic sonography is typically used to create an audio "image", such as during pregnancy to visualize the developing baby.
[1] Knee or hip replacement are, by themselves, not indications to perform the procedure. [2] Serial follow-up the ultrasound exam is not necessary after an initially complete, normal study in individuals with DVT symptoms who have suspected pulmonary embolism and nondiagnostic ventilation/perfusion scans. [3]
For example, in chemical kinetics, it has been observed that ultrasound can greatly enhance chemical reactivity in a number of systems by as much as a million-fold; [15] effectively acting to activate heterogeneous catalysts. In addition, in reactions at liquid-solid interfaces, ultrasound breaks up the solid pieces and exposes active clean ...
Image credits: milwbrewsox #7. My wife and I have this ceiling fan/light in our bedroom in the house we moved into two years ago. It has a remote control for the fan and lights.
[1] Contrast-enhanced ultrasound (CEUS) is the application of ultrasound contrast medium to traditional medical sonography. Ultrasound contrast agents rely on the different ways in which sound waves are reflected from interfaces between substances. This may be the surface of a small air bubble or a more complex structure.