A demonstration device that provides interactive demonstrations receives user input during a demonstration session. Also, the LD ratio is shorter than in a traditional laminar flow element, so that for at least part of its range its operation is determined by the behavior of boundary layers forming on those surfaces. The opposed ends of the flange members are spaced from each other and define a gap therebetween. The second port directs a separated material collected from the second port inlet out of the processing bag. The elevator comprises at least one protrusion engaging the inclined groove. In contrast to prior art, the present invention advantageously encapsulates the quorum in a software construct, called a quorum object, which is disassociated from the cluster as a whole and spans a designated subset of the cluster’s membership.