A persistent personal messaging system provides tuple space functionality supporting a user changing between a plurality of client devices, even within a loosely coupled, distributed system for persistent personal messaging. The battery pack has one or more cells that lack an outer coverage except for a polymer sheathing. The passages are disposed in a circle facing the selecting device such as to guide the flow of the cerebrospinal fluid traversing the passage of the selecting device through the selected passage of the resistance system. To form an estimate of the number of tuples matching a pattern matching predicate, statistics are retrieved for the matching characters in each matching position in the predicate, and then combined to produce the estimate. An electrostatic test element group may be formed in at least one of the dummy pixels.