A recording medium having a spare area for defect management, and a method and apparatus for allocating and assigning the spare area. One or more of the signals following the stress event are analyzed so as to evaluate a stress response of the patient. The first and second portions are electrically isolated from one another by a nonconductive bushing. Kits and articles of manufacture are also provided. According to the invention, the first and the second axis of rotation lie in a plane inclined at an angle \u03b1 ranging between 80\xb0 and 100\xb0 with respect to a plane of the base plate.