Methods of treating an injured vertebrate spinal cord are described. One method is based on a differential pressure between a suction airflow path and ambient air and includes: detecting the differential pressure, comparing the detected differential pressure to a predetermined threshold, and, when the detected differential pressure is less than the predetermined threshold, initiating a predetermined control procedure. During a second feeding period where the motor is driven at a speed over the given speed, the controller controls the potential such that the coils are opened by turning off the transistors or the potential becomes the power-supply voltage potential. The wafer is then positioned in a plasma etch chamber with an active surface of the wafer exposed, and a surface layer etched away by an oxygen plasma without causing any further silicon oxide formation on the backside of the wafer. More specifically, the PSE controller is configured to deliver over 15.