Closed Book Examination
1. A reasonably strong man can lift a 60 lb. weight from the floor, push it above his head and return it to the floor in about three seconds, lie can probably repeat this lift twice more within a total of 10 seconds for the three complete lifts and returns. From what you know of the biophysics of muscle, estimate the average temperature rise of the man due to this exercise just after finishing the lifts, assuming that ho cannot lose or gain appreciable heat externally during this time and that his weight is 180 lb. Assume that his average specific heat is that of water. Be sure to mention your reasons for including or excluding principal factors in your calculations as only about half credit will be given for a correct calculation without discussion.
2. Two frontal plane electrocardiographic leads are available on a person, one (#1) of transfer impedance strength 0..5 ohm/om., the second (#2) of 0.8 ohm/cm. Both leads lie strictly in the frontal plane and for a given dipole source location can be represented by a vectorial transfer impedance in the horizontal plane for #1 and 60 ° above the horizontal for #2. A dipolar current moment source at the above location produces -1.0 millivolts of potential in lead #1 and -1.6 millivolts in lead #2. Determine the magnitude and direction of the source, assuming that it also lies in the frontal plane.
3. Write a short but information—filled resumé of one of the following topics, using quantitative formulation where possible.
a) The dynamics of excitation and contraction in striated muscle.
b) The biophysical basis of the electrocardiogram.
e) The visual physiology and biomathematics of stereoscopic spatial vector cathode ray displays and their angular reresolution.