There are 26 new articles in PLoS ONE today. As always, you should rate the articles, post notes and comments and send trackbacks when you blog about the papers. You can now also easily place articles on various social services (CiteULike, Mendeley, Connotea, Stumbleupon, Facebook and Digg) with just one click. Here are my own picks for the week - you go and look for your own favourites:
High predictive validity - that is, a strong association between the outcome of peer review (usually, reviewers' ratings) and the scientific quality of a manuscript submitted to a journal (measured as citations of the later published paper) - does not as a rule suffice to demonstrate the usefulness of peer review for the selection of manuscripts. To assess usefulness, it is important to include in addition the base rate (proportion of submissions that are fundamentally suitable for publication) and the selection rate (the proportion of submissions accepted). Taking the example of the high-impact journal Angewandte Chemie International Edition (AC-IE), we present a general approach for determining the usefulness of peer reviews for the selection of manuscripts for publication. The results of our study show that peer review is useful: 78% of the submissions accepted by AC-IE are correctly accepted for publication when the editor's decision is based on one review, 69% of the submissions are correctly accepted for publication when the editor's decision is based on two reviews, and 65% of the submissions are correctly accepted for publication when the editor's decision is based on three reviews. The paper points out through what changes in the selection rate, base rate or validity coefficient a higher success rate (utility) in the AC-IE selection process could be achieved.
Enhanced characterization of sleep architecture, compared with routine polysomnographic metrics such as stage percentages and sleep efficiency, may improve the predictive phenotyping of fragmented sleep. One approach involves using stage transition analysis to characterize sleep continuity. We analyzed hypnograms from Sleep Heart Health Study (SHHS) participants using the following stage designations: wake after sleep onset (WASO), non-rapid eye movement (NREM) sleep, and REM sleep. We show that individual patient hypnograms contain insufficient number of bouts to adequately describe the transition kinetics, necessitating pooling of data. We compared a control group of individuals free of medications, obstructive sleep apnea (OSA), medical co-morbidities, or sleepiness (n = 374) with mild (n = 496) or severe OSA (n = 338). WASO, REM sleep, and NREM sleep bout durations exhibited multi-exponential temporal dynamics. The presence of OSA accelerated the "decay" rate of NREM and REM sleep bouts, resulting in instability manifesting as shorter bouts and increased number of stage transitions. For WASO bouts, previously attributed to a power law process, a multi-exponential decay described the data well. Simulations demonstrated that a multi-exponential process can mimic a power law distribution. OSA alters sleep architecture dynamics by decreasing the temporal stability of NREM and REM sleep bouts. Multi-exponential fitting is superior to routine mono-exponential fitting, and may thus provide improved predictive metrics of sleep continuity. However, because a single night of sleep contains insufficient transitions to characterize these dynamics, extended monitoring of sleep, probably at home, would be necessary for individualized clinical application.