In one aspect, a method for providing context regarding an addition to a social graph is provided. Image data comprising the composite action is received and used to generate a feature vector, such as a combination of a horizontal translation, a vertical translation, a scale value and a skin detection value, that is associated with the composite action. When applied to bodily tissues, current pulses or voltage pulses having the multi-phasic waveform provide increased specificity and sensitivity in probing tissue. The system accurately models the effects of metastability by, at appropriate times during simulation, pseudo-randomly inverting outputs of registers receiving clock-domain-crossing signals.