The increase in moral depreciation of fixed capital has as its corrollary
the accelerated turnover-time of fixed capital, discussed in more detail in
E. Mandel, Late Capitalism, chapter 7. Mandel cites a reference on p. 226n
which may be of interest: Allan H. Young, "Alternative estimates of
Corporate Depreciation of Profits", Parts 1 & 2, Survey of Current
Business, Vol. 48, No. 4 and 5, April and May 1968. There are some other
analyses of depreciation in that journal as well.
Cheers
Jurriaan Bendien
Amsterdam