A light beam preparation arrangement includes a light tunnel, a rotatable unit, and a drive unit. For example, if a first user shares a hyperlink to content in an online social networking system with one or more other users, the user may specify the information to be shared in association with the hyperlink, such as one or more images to be shared in association with the hyperlink and a summary to be shared in association with the hyperlink. An elastomeric retaining element adjacent to the fluid path is constrained to deform substantially perpendicular to the fluid path, so that the retaining element is operable to vary the cross-sectional area of the fluid path inversely to a change in temperature. In the first configuration the RFID device is adapted to communicate with a standard RFID reader via the communication interface. The correlated training samples correspond to a number of receive antennas through which the training sequence was received.