The invention provides an optical disk that enables high-speed reproduction of address signals. is a cyclic group represented by a general formula, Y in the formula is a cyclic linking group having a carbonyl group and a site containing an unsaturated carbon bond adjacent to the carbonyl group, and E in the formula is a bonding group having at least one amide bond and at least one of divalent organic groups which may be substituted. The radioactive material may be introduced into the energy cell by a wetting process. The invention also relates to a needleless injection device. The apparatus comprising: adjustment means for positioning the boom at the null point; actuator means for moving the adjustment assembly; and interface means having hard mineral members for interfacing the actuator means with the adjustment means for reducing occurrences of micro-mechanical movement when the mass position adjustment apparatus is not being operated. In one embodiment, the method comprises performing layout analysis on an electronic version of a document to locate text zones, assigning attributes for scale and importance to text zones in the electronic version of the document, and reformatting text in the electronic version of the document based on the attributes to create an image.