In a community of mobile devices, a non-participating device can be joined to the community if the non-participating device meets location dependent criteria. In an embodiment, a namespace system includes a network resource that has a resource permission, and includes a namespace that has one or more members associated with the namespace. The pitch is determined so that ions implanted through each opening diffuse toward those implanted through an adjacent one to form wells. Preferred liquid carriers are selected from semifluorinated alkanes. Other systems, methods, and computer program products are presented in additional embodiments. Differential amplifiers receive a ratiometric response signal from the ratiometric device, and output measurement signals based on the ratiometric signal.