An on-chip data independent method and apparatus for channel error estimation in a data recovery scheme is based on measuring phase noise statistics. The power storage device includes a current collector, a mixed layer formed over the current collector, and a crystalline silicon layer which is formed over the mixed layer and functions as an active material layer. Where a rare-earth element concentration in the third ceramic layers is compared to a rare-earth element concentration in outermost layer portions including at least outermost surfaces of the first and second outer layer portions, CR>Cr. The device is attached to the user’s head in a manner such that the outer housing sighting marking and an aligned inner member position bull’s eyes can be seen by the user.