A database tool comprises a computer-implemented method for quick low-intensity processing to identify latent relationships among data elements in very large databases and to determine whether a keyword or character string is contained in a document which is part of a large collection of documents. A stiffener includes an embedded power bus bar structure for distributing power. The pressure of the fluid is transferred through the flexible barrier to the pressure receiving surface. Therefore, the advertisement apparatus using a light switching device can be used for both indoor and outdoor advertising displays.