[R] tutorial for lme

[Martin Olivier]

Hi all,

I find an introduction for program lme()  for fitting mixed effects models.
I do not have the book wirtten by Pinheiro and Bates, and a tutorial 
would be very useful.
In particular, I have some difficulties to understand how specifications 
for random effects and variance structures
could be specified.

somebody knows an introduction for that ?
Thanks,
Olivier