my definitive version according to Mila's comments

Essentially this version contains a rewrite of the various parts of
the abstract. It also contains minor modification to the results, the
methods and the discussion according a skype session between Israel
and myself today.

Still to be done is the cross referencing between the article and the
figures and tables of the supplementary material, marked as Figure S*
and Table S* (and in magenta) in the main text of the article.

rr
Merge branch 'master' of github.com:ajholanda/psa