To join in the discussion you need to Register on the website.
If you are a registered user you need to use the "submit article " link.
Contributions should be up to 1000 words (maximum). If you are responding to specific points made by other contributors, please reference them as Luepnitz - comment one, Prall - comment two etc. Please include your name and affiliation for identification purposes.
We encourage a lively and forthright discussion, but reserve the right to edit contributions appropriately.