This invention proposes a computer-implemented system for managing a collection of Web documents with dependency relationships defined among designated elements of those Web documents. The actuator includes a worm shaft and a lead screw. 6, and the amount of Si measured by ICP atomic emission spectrometry is in the range of 500 to 4,000 ppm. A rotating agitator with at least two arms and associated paddles may be mounted for rotation in the transition about a substantially vertical axis for agitating the material in the transition. The backside electrode is elongated to the wiring portion.