"Stephen Tonkin" wrote in message
...
Peter Bull wrote:
is there is any discernible expansion

Yes.


"Expanding" slightly on this, Virginia Trimble's PhD thesis was on this
topic back in 1970-ish. I'm sure further work has been done since. A
search on ADS shoudl bring it forward, and you can read the original paper
if you want.

--
Mike Dworetsky

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