Laser material is pumped and its stored energy is extracted in a heat capacity laser mode at a high duty factor. The system determines where to present impressions, such as advertisements, to maximize an expected utility subject to one or more constraints, which can include quotas and minimum utilities for groups of one or more impression. The inner core is configured to rotate radially around a longitudinal axis of the elongated member, and the imager can be configured to image a body tissue and output an image signal to an imaging system communicatively coupled with the imager. The blocks slide along the inclined sides of the protrusions and then stopped by the vertical sides of the protrusions. The conventional inflatable knee airbag is stored within the housing and in communication with an inflator.