Note: one figure in this paper was drawn on a Macintosh, which doesn't
generate Encapsulated PostScript.  The result is that the figure doesn't
get included correctly in the document.  In ./Paper.ps we included a
bitmap rendition of this figure, but it does not come out as sharp as
the original figure.  Therefore, we have included the original figure in
this directory as well (in ./Figure2.ps).  You can print, photo-reduce
by 64%, and cut/paste this figure in place over the bitmap.

Note that this figure is being used and reprinted by permission of
Merit, Inc.