The invention provides methods and appartaus for analysis of images of two-dimensional bar codes in which a model that has proven successful in decoding of a prior 2D image of a 2D bar code is utilized to speed analysis of images of subsequent 2D bar codes. In one implementation, a system includes a messaging server component to provide messaging services and an application server component to provide a networked application. Also provided is a method of reading a memory cell that comprises applying a potential difference to a selected memory cell by providing a column line potential and a row line potential. A relationship between a degree of detuning fdfs, where fd is the resonance frequency in the driving vibration mode and fs is the resonance frequency in the detecting vibration mode, and a value Qs in the detecting vibration mode is given. The contractible hose is fitted with at least one pyrotechnic gas generator.