1. (a) Sketch the load characteristics, terminal voltage/load current, of the following types of DC generator: (i) series-connected, (ii) shunt-connected and (iii) compound-connected. (b) State one purpose for which….
With an unfocused transducer, for which of the exposures listed here are there no confirmed significant biological effects in mammalian tissue?
1. Biological studies of the cytoskeleton have shown:
a. ultrasound increases the risk of cavitation
b. ultrasound-induced changes are temporary
c. ultrasound produces long-term tissue damage
d. ultrasound increases the risk of tissue hyperplasia
2. The use of contrast agents in diagnostic sonography:
a. has induced cell changes
b. may increase the risk of cavitation
c. demonstrates a rapid increase in tissue temperature
d. determines the conditions under which thermal effects occur
3. Limiting the exposure time to a fetus is an example of:
a. Snell’s law
b. mechanical index
c. ALARA principle
d. Huygens principle
4. Experimentation on living tissue in an artificial environment describes which of the following?
a. in situ
b. in vivo
c. ex situ
d. ex vivo
5. Heat is most dependent on which of the following intensities?
6. Pulses can induce cavitation in mammals with a peak intensity exceeding:
a. 10 MPa
b. 20 MPa
c. 10 W/cm2
d. 2000 W/cm2
7. Higher intensities are necessary to produce bioeffects with a(n):
a. focused transducer
b. unfocused transducer
c. multifrequency transducer
d. three-dimensional transducer
8. Which type of cavitation involves the microbubbles already present in tissues?
9. With an unfocused transducer, for which of the exposures listed here are there no confirmed significant biological effects in mammalian tissue?
a. 1 W/cm2
b. 1 mW/cm2
c. 100 W/cm2
d. 100 mW/cm2
10. The average intensity during the pulse repetition period defines:
a. spatial average
b. temporal average
c. spatial average–pulse average
d. spatial average–temporal average