7.5 A low-pass filter is added to the catheter of a pressure-sensor-catheter- sensor system by pinching the catheter. The system consists of a Statham P23Dd sensor and a 1 m, 6 F, polyethylene catheter. The pinch effectively reduces the diameter of the catheter to 25% of its original diameter. a. c. How long must the pinch be for the system's damping factor to be equal to 0.7? b. Sketch the frequency response for the system with and without the pinch. Sketch the time response for the system with and without the pinch when it is excited by a 100 mm-Hg step input. d. Discuss how faithfully the two systems will reproduce the blood-pressure waveform for humans, dogs, and shrews with heart-rate variations of 1 to 3.3 beats/s, 1.5 to 5 beats/s, and 12 to 22 beats/s, respectively.