A constant current driver circuit based on a half-bridge resonant topology has a variable capacitance circuit. In some situations, the techniques include managing communications for computing nodes of a managed computer network by using one or more particular computing nodes of the managed computer network that are configured to operate as intermediate destinations to handle at least some communications that are sent by andor directed to one or more other computing nodes of the managed computer network. The axial rod is disposed under the flange of the scan carriage. Then, the annealing in a hydrogen atmosphere with vapor added therein is performed. An exemplary medium includes a basal medium, a serum substitute, and a cytokine formula.