A can end member has a center panel, a circumferential chuck wall, and a transition wall. During operation, the system obtains a digital image in which the image components are de-correlated into separate channels containing luminance information and chrominance information. Servo data are written to a disc of the HDA as a number of p angularly spaced apart servo data fields, the servo data used by a servo control circuit to effect head positional control. The keel includes various configurations of transverse members extending away from the longitudinal axis. The prepolymer compositions contained in the tube can be maintained at a temperature for a time sufficient to form the desired graded index profile. The output circuit comprises a diode coupled in series with a capacitor both coupled in parallel with the semiconductor switch.