Access to a wireless network is attempted by sending on a random access channel RACH at a first transmit power a first preamble comprising a signature sequence that is randomly selected from a set of signature sequences. A sensor unit is attached to the lower unit and includes a lower sensor holder and an upper sensor holder which are disposed in opposition to each other via the paper path. In one embodiment, media is transmitted to the receiver from a plurality of sources. Alternately, if the car is inert weight, cables can drive stationary generators. The invention further provides a modified APP protein and associated nucleic acids, peptides, vectors, cells, and cell isolates, and assays that are particularly useful for identifying candidate therapeutics for treatment or prevention of Alzheimers disease.