Apparatus and methods for transaction processing. Also, a method that includes the steps of posting a user search query from a user on a bidding bulletin board, receiving a bid from an agent at the bidding bulletin board in response to the query, where the agent is associated with a search result, and displaying the search result if the bulletin board accepts the bid, where the amount bid is determined by behavioral rules for the agent. The outer diameter and microneedle length is also very important, and in combination with the separation distance will be crucial as to whether or not the microneedles will actually penetrate the stratum corneum of skin. Although the preferred embodiment of this invention is to produce a dissolved oxygen solution for use in humans as a means of delivering oxygen to the portal vein system for treatment of various disorders, it is in no way limited to this particular application. Otherwise, the node handles the detected event using a fallback action.