We have now received the referee report(s) on this paper, which is being
considered by Journal of Physics D: Applied Physics. The referee(s) have
recommended that you make some amendments to your paper.
Please can you amend your paper following the referee recommendations, and
then send us the amended version together with a list of the changes you
have made. This will help the referee(s) to make the final decision.
We would be grateful if you could complete your amendments as quickly as
possible and send in your amended paper and electronic files by 5 October
2009. If we receive your paper after this date, it may be treated as a new
submission, so please let us know if you will need more time.