As you might then expect, the preferred audience is professional scientists (and engineers). Typically, a scientist might direct her paper here, instead of a journal in her field, if she expects that her results might be considered of interest to a broader science community. Oh, and it would raise her profile amongst them, which certainly is desirable.

Another important use of this journal is to search for job vacancies in your field. Many American and overseas universities list tenure track and postdoctoral positions here. But beware! Some fraction of these positions already have preferred candidates. The universities are only advertising here to comply with EEO rules, and may often slant the ad or filter the resultant applications to ensure that only the desired candidate gets the job.