Systems and methods to authenticate and process requests received via social networking websites. The method comprises the step of administering to the subject an effective amount of a compound represented by Formula :The values of the variables in Formula are described herein. The recipient may be selected from a target list of recipients identified with a sponsor, wherein the message includes a reference to the target list. Inlet-end and outlet-end oscillations are registered by means of a sensor arrangement. The inlet region may have a generally tubular inlet opening.