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  2. Ultrasound - Wikipedia

    en.wikipedia.org/wiki/Ultrasound

    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.

  3. Congruence (manifolds) - Wikipedia

    en.wikipedia.org/wiki/Congruence_(manifolds)

    our congruence might become a geodesic congruence. Indeed, in the example from the preceding section, our curves become geodesics on an ordinary round sphere (with the North pole excised). If we had added the standard Euclidean metric d s 2 = d x 2 + d y 2 {\displaystyle ds^{2}=dx^{2}+dy^{2}} instead, our curves would have become circles , but ...

  4. Medical ultrasound - Wikipedia

    en.wikipedia.org/wiki/Medical_ultrasound

    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.

  5. Hilbert's axioms - Wikipedia

    en.wikipedia.org/wiki/Hilbert's_axioms

    Removing five axioms mentioning "plane" in an essential way, namely I.4–8, and modifying III.4 and IV.1 to omit mention of planes, yields an axiomatization of Euclidean plane geometry. Hilbert's axioms, unlike Tarski's axioms, do not constitute a first-order theory because the axioms V.12 cannot be expressed in first-order logic.

  6. Pons asinorum - Wikipedia

    en.wikipedia.org/wiki/Pons_asinorum

    The pons asinorum in Oliver Byrne's edition of the Elements [1]. In geometry, the theorem that the angles opposite the equal sides of an isosceles triangle are themselves equal is known as the pons asinorum (/ ˈ p ɒ n z ˌ æ s ɪ ˈ n ɔːr ə m / PONZ ass-ih-NOR-əm), Latin for "bridge of asses", or more descriptively as the isosceles triangle theorem.

  7. Ultrasound energy - Wikipedia

    en.wikipedia.org/wiki/Ultrasound_energy

    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.

  8. Ultrasonography of chronic venous insufficiency of the legs

    en.wikipedia.org/wiki/Ultrasonography_of_chronic...

    The reflected ultrasound is received by the probe, transformed into an electric impulse as voltage, and sent to the engine for signal processing and conversion to an image on the screen. The depth reached by the ultrasound beam is dependent on the frequency of the probe used. The higher the frequency, the lesser the depth reached. [9]

  9. Congruence (geometry) - Wikipedia

    en.wikipedia.org/wiki/Congruence_(geometry)

    Congruence permits alteration of some properties, such as location and orientation, but leaves others unchanged, like distances and angles. The unchanged properties are called invariants. In geometry, two figures or objects are congruent if they have the same shape and size, or if one has the same shape and size as the mirror image of the other ...