Method and system for determination of a reference printer state using recursive tone scale matching. According to one aspect of the present invention, return scenarios for optimized portfolio allocations are simulated interactively to facilitate financial product selection. Sliding contact is further reduced by the piston or wall having contact ribs extending axially. The connection portion is connected to the display module and is supported by the base to be rotatable about a rotation axis that extends vertically. The assembly includes a flexible annular seal, a ring, and a plurality of retainers. The gas-liquid contacting apparatus can include a member.