The concentration of air or other agents in a fluid delivery line is determined by monitoring agent signals and processing those agent signals along with information regarding the age of each agent signal. The bandgap reference generator includes a second leg that includes a PMOS transistor, an NMOS transistor, a resistor and a pnp bipolar junction transistor. At least one digital camera converts the light imageable shape of each of the targeting sights to individual pixel images. The target features and the dummy features are assigned to multiple masks based at least in part on one or more mask-assignment rules. A spot of the laser beam on the projection mask is shaped so as to irradiate a portion in the vicinity of first edges of the light transmitting area, the first edges extending in one direction, and so as not to irradiate a portion in the vicinity of second edges of the light transmitting area, the second edges extending in a second direction which is different from the first direction. The actuating member is designed to cause the tray to pivot by gravity into correspondence with a receiving container selected in accordance with the object transported by the tray.