Nature Publishing Group believes that advance online publication (AOP) is the best and quickest way to publish high-quality, peer-reviewed research for the benefit of readers and researchers. All papers published AOP, for any NPG journal, are the definitive version: they will not change before appearing in print and can be referenced formally as soon as they appear on NPG's AOP website.

Our AOP timetable
embo Reports will publish a few AOP papers each week, within the AOP section of the embo Reports website.

The monthly Nature Research Journals publish papers within the AOP section of the site on Monday each week. Articles whose publication is exceptionally urgent may be uploaded on other days on a fast-track schedule. Currently Nature Cell Biology, Nature Genetics, Nature Immunology, Nature Neuroscience, Nature Structural Biology Nature Biotechnology, Nature Medicine and Nature Materials all publish AOP papers.

Some frequently asked questions about AOP

Is the AOP version of the article definitive?
Yes. Different publishers have different policies, and some journals publish unedited or partly edited versions of articles on their web sites before publishing them in print. Nature's, and NPG's, policy, however, is to publish online only the final version of the paper, exactly as it will be published in the printed edition. The paper is thus complete in every respect except that instead of having a volume/issue/page number, it has a DOI (Digital Object Identifier). This means that the paper can be referenced as soon as it appears on the AOP site by using the DOI.

What is a Digital Object Identifier?
A digital object identifier (DOI) is an international, public, "persistent identifier of intellectual property entities" in the form of a combination of numbers and letters. For NPG content the DOI is assigned to an item of editorial content, providing a unique and persistent identifier for that item. The DOI system is administered by the International DOI Foundation (http://www.doi.org), a not-for-profit organization. CrossRef (http://www.crossref.org), a not-for-profit organization making the DOI a reference linking standard and enabling cross-publisher linking, maintains the lookup system for DOIs. NPG is a founding and board member of CrossRef.

What do the numbers in the DOI signify?
The DOI has two components, a prefix (before the slash) and a suffix (after the slash). The prefix is a DOI resolver server identifer (10) and a unique identifier assigned to the publisher—for example, the identifier for NPG is 1038 and the entire DOI prefix for an article published by NPG is 10.1038. The suffix is an arbitrary number provided by the publisher. It can be composed of numbers and/or letters and does not necessarily have any systematic significance. Each DOI is registered in a central resolution database that associates it with one or more corresponding web locations (URLs). For example, the DOI 10.1038/ng571 connects to http://dx.doi.org/10.1038/ng571

Can I use the DOI in a reference citation?
Yes, instead of giving the volume and page number, you can give the paper's DOI at the end of the citation. For example, Nature papers should be cited in the form;

Author(s) Nature advance online publication, day month year (DOI 10.1038/natureXXX).

After print publication, you should give the DOI as well as the print citation, to enable readers to find the paper in print as well as online. For example;

Author(s) Nature volume, page (year); advance online publication, day month year (DOI 10.1038/natureXXX).


How can I use a DOI to find a paper?
There are two ways to use a DOI to find a paper:

1. DOIs from other articles can be embedded into the linking coding of an article's reference section. In Nature journals these appear as "|Article|" in the reference sections. When |Article| is clicked it opens another browser window leading to the entrance page (often the abstract) for another article. Depending on the source of the article, this page can be on the NPG's site or a site of another publisher. This service is enabled by CrossRef.

2. A DOI can be inserted directly into the browser's location bar For example, for the DOI 10.1038/ng571, typing http://dx.doi.org/10.1038/ng571 brings up the entrance page of the article.


What is the official publication date?
Many journals, and most abstracting and indexing services (including Medline and ISI) cite the print date as the publication date. This is an evolving standard, however, and publishers are increasingly stating both the 'online publication date' and the 'print publication date'. NPG will continue to publish both dates for our own papers, and we hope that the scientific communities and abstracting and indexing services will recognize these dates.

Many journals, and most abstracting and indexing services (including Medline and ISI) cite the print date as the publication date. This is an evolving standard, however, and publishers are increasingly stating both the 'online publication date' and the 'print publication date'. NPG will continue to publish both dates for our own papers, and we hope that the scientific communities and abstracting and indexing services will recognize these dates.

For legal purposes (for example, establishing intellectual property rights), we assume that online publication constitutes public disclosure. But this is for the courts to decide; NPG's role as a publisher is to provide clear documentation of the publication history, online and in print.

Must I subscribe to the journal in order to read AOP articles?
Yes. AOP papers are the same as those in the print issues: while abstracts are freely available on any NPG journal's web site, access to the full-text article requires a paid subscription or a site license.

Does Medline use DOIs?
Medline currently captures DOIs with online publication dates in its records, and is developing an enhanced level of support for the DOI system.

Does The Institute for Scientific Information use DOIs?
ISI (Institute for Scientific Information) currently captures DOIs in its records at the same time as the volume/issue/page number. Therefore, ISI is not using the DOI to capture information before print publication, but rather as an additional piece of metadata.

How does AOP affect the calculation of impact factors?
Impact factors are calculated by ISI. At present, ISI bases its calculations on the date of print publication alone, so until or unless ISI changes its policy, AOP has no effect on impact factors.

For a full explanation of how impact factors are calculated, see: http://scientific.thomson.com/free/essays/journalcitationreports/impactfactor/.

What are the page numbers that appear in PDFs of AOP papers?
For convenience, the PDF version of every AOP article is given a temporary pagination, beginning with page 1. This is unrelated to the final pagination in the printed article.