Contributors explore a common theme or question under the direction of a single editor or editorial team, which changes every three months or so. Reading periods tend to be a month long, but vary in their exact timing from year to year. If you d like to get our calls for submission via email, please sign up for our email newsletter (via MailChimp). We also have a news feed on Twitter and Identi.ca, and even (God help us) a Facebook page.Complete guidelines are now at our submissions manager,...