The invention provides a database schema for representing a workflow process definition. For example, a nanocapillary can dispense a liquid near a region of interest, the liquid evaporating to increase the vapor pressure near the fluorescent markers. An engaging member which resists disassembly of the clips may be included. The controller may be configured to generate a third signal indicative of a desired fan speed based on the first signal, and a fourth signal indicative of a difference between the desired fan speed and the actual fan speed.