We are pleased to begin an experiment during the last quarter of 2007 in which we will publish online letters to the editor concerning PNAS articles published within the last 3 months. We wish to provide readers with an opportunity to constructively address a difference of opinion with authors of recent papers. Readers are encouraged to point out potential flaws or discrepancies or to comment on exceptional studies published in the journal. Replication and refutation are cornerstones of scientific progress, and we welcome your comments. However, we will not publish requests to cite the letter writer's work, accusations of misconduct, or personal comments to an author. Letters will be short (no longer than 250 words) and may contain no more than five references. The corresponding author of the paper being discussed will be sent a copy of the letter and permitted to prepare a response. Whenever possible, the submitted letter and author response will appear online concurrently. We will allow only a single response to ensure that the issues addressed are substantial.
We hope that you find these letters an exciting and intellectually stimulating addition to PNAS. For submission details, see the Information for Authors at http://www.pnas.org/misc/iforc.shtml.