2.7 Shock Waves and Sonic Booms

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2.7 Shock Waves and Sonic Booms

• http//www.kettering.edu/drussell/Demos/doppler/d
  oppler.html

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2.8 Ultrasonics
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The Frequency of a Sound Wave
Audible Range 20 Hz ----- 20,000 Hz. Infrasonic
waves Sound waves with frequencies lt 20
Hz. Ultrasonic waves Sound waves with
frequencies gt 20,000 Hz.
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Bats and ultrasonic sound waves
Bats use ultrasonic frequencies up to 100 kHz for
locating their food sources and navigating.
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Infrasonics
Rhinoceroses use infrasonic frequencies as low as
5 Hz to call one another.
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Piezoelectric Transducer
Piezoelectric transducer is used to produce and
detect Ultrasonic Waves. It is a quarts crystal
which converts electrical oscillations into
mechanical vibrations (sound) and vice versa.
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Applications of Ultrasound in Medicine

1. Ultrasonic Scanner
2. The cavitron ultrasonic surgical aspirator (CUSA)
   
3. Bloodless surgery High-intensity focused
   ultrasound (HIFU)
4. The Doppler flow meter

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Ultrasonic Scanner
Ultrasound reflects from boundaries between two
different media. Ultrasound can be used to
identify a wide range of soft tissues, whereas
X-rays are useful primarily in seeing hard
tissue, such as bones. Ultrasound is
non-ionizing, doesnt ionize atoms or break up
molecular bonds. It is safe to use in obstetrics.

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The cavitron ultrasonic surgical aspirator (CUSA)
Neurosurgeons use a cavitron ultrasonic surgical
aspirator (CUSA) to cut out brain tumors
without adversely affecting the surrounding
healthy tissue.
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Bloodless surgery High-intensity focused
ultrasound (HIFU)
Another application of ultrasound is in a new
type of bloodless surgery, which can eliminate
abnormal cells, such as those in benign
hyperplasia of the prostate gland. This
technique is known as HIFU (high-intensity
focused ultrasound). It is analogous to focusing
the suns electromagnetic waves by using a
magnifying glass and producing a small region
where the energy carried by the waves can cause
localized heating. Ultrasonic waves can be used
in a similar fashion. The waves enter directly
through the skin and come into focus inside the
body over a region that is sufficiently well
defined to be surgically useful. Within this
region the energy of the waves causes localized
heating, leading to a temperature of about 56 C
(normal body temperature is 37 C), which is
sufficient to kill abnormal cells. The killed
cells are eventually removed by the bodys
natural processes.
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Doppler Flow Meter
A Doppler flow meter measures the speed of red
blood cells.
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Research Articles Compressibility of
gastrointestinal tract tumors during
transabdominal sonographic examination A clue to
the diagnosis of gastrointestinal lymphoma (p
59-62)Yasutomo Fujii, Nobuyuki Taniguchi, Harumi
Koibuchi, Yoshikazu Yasuda, Hideo NagaiPublished
Online Jul 30 2007 337PMDOI 10.1002/jcu.20393
Sonographic examination of the appendix in acute
infectious enteritis and acute appendicitis (p
63-66)Koichi Yabunaka, Toshizo Katsuda, Shigeru
Sanada, Hidetoshi Yatake, Tsunemasa
FukutomiPublished Online Jul 27 2007
202PMDOI 10.1002/jcu.20394 Ductus venosus
blood flow resistance and congenital heart
defects in the second trimester (p 72-78)Jeng
Hsiu Hung, Chong Yau Fu, Jen-Her Lu, Chia-Yi
Selena HungPublished Online Aug 3 2007
145PMDOI 10.1002/jcu.20406
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2.9 Infrasonics
Infrasonics refers to waves whose frequencies lie
below the audible frequency range. Earthquake
waves are infrasonic waves. There are 3 types of
earthquake waves S-wave A transverse body
wave, can only propagate in solid rock. P-wave
A longitudinal body wave, propagates at the speed
of sound, and has a very large range. L-wave
The wave that forms along a boundary between two
mediums such as air and ground and is responsible
for the immense damage that can occur in large
earthquakes. A variety of animals and birds are
sensitive to infrasonic waves. Many zoologists
believe that the sensitivity of such animals as
elephants or cattle could provide them with an
early warning of earthquakes and weather
disturbances.
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Motion Sickness
For vibration at very low frequencies, motion
sickness of people in boats must have been one of
the earliest noticeable effects. The human body
is particularly sensitive to vibrations and
infrasound near 7 Hz, at which frequency there is
an overall mechanical resonance of organs in the
abdominal and chest cavities. Fromhttp//www.a
nswers.com/topic/infrasound?cattechnology
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Waves 1 and Wave 2
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Wave 1, Wave 2, and Sum