R help - Jan 2011 - R syntax for 95% prediction interval on a left-truncated normal variable

Hi all,
I am searching for a R procedure to calculate a 95% prediction interval
(i.e. the interval in which following observations of the variable will
occur, not a confidence interval) on a variable that is the natural
logarithm of a ratio that  is always equal ore superior to 1, so the
natural-log-transformed variable is left truncated from 0 and I think that
it is expected to be normal; anyone can help? ThankYou,
Fabio 

Dott. Fabio Colombo
Coordinatore tecnico
Universit? degli Studi di Milano, Dipartimento di Scienze e Tecnologie
Veterinarie per la Sicurezza Alimentare, Laboratorio di Identificazione di
Specie (LIS)
Via A. Grasselli, 7, 20131 Milano, Italy
Phone: +390250318504
Fax: +390250318501
E.mail fabio.colombo at unimi.it