The Methods section appears in all online original research
articles and should contain all elements necessary for interpretation
and replication of the results. Methods should be written as concisely
as possible and typically do not exceed 3,000 words. Methods-only
references do not count against your reference limit. We encourage
you to deposit any step-by-step protocols used in your study in
Protocol Exchange, an open resource maintained by NPG. These
protocols are linked to the Methods section upon publication