An ambulance cot is disclosed and the ambulance cot has, if desired, a wheel supported base and a litter raisable and lowerable by a powered elevating mechanism oriented between the base and the litter. This apparatus includes a frame, a system for attaching the frame to a tractor, and a soil moving blade assembly mounted to the frame. The base include an inner surface and an outer surface and a plurality of channels in the base for interlocking the porous pad material with the base. The network drivers are then configured to intercept the data traffic of these guest VMs and route it through their corresponding virtual security agents, thus providing a \u201cslow-path\u201d for intrusion detection and prevention. The second factor considered is the impact of the weight assigned to each observation on the overall parameter estimate. A histogram of signal state transition times can be prepared from the edge probability density.