Examining the viability of dorsal fin pigmentation for individual identification of poorly-marked delphinids.

Dolphin photo-identification has traditionally relied only on distinctive markings on the dorsal fin-this is problematic for delphinids whose populations exhibit a low mark ratio. We used common dolphins (genus Delphinus) as a model species to assess the viability of using pigmentation for photo-identification. Using a photo-identification catalogue of 169 adult individuals collected between 2002 and 2013, we extracted features that quantified pigmentation in a manner that was robust to lighting artefacts and dorsal fin orientation. We determined the proportion of individuals which exhibited pigmentation and examined temporal stability by (i) visually examining individuals and (ii) testing for seriation. We found 88-91% of images could be manually matched to the correct individual in the catalogue based on pigmentation patterns alone. A linear discriminant analysis classifier correctly identified the correct individual 77% of the time. We found 95% common dolphins exhibited distinctive pigmentation-all of which were temporarily stable. Our work challenges the current thinking that pigmentation is an unreliable feature for delphinid photo-identification and suggests that this feature could be applied to common dolphins and other poorly-marked delphinids.

The effect of time of day on the duration of neuromuscular blockade elicited by rocuronium.

In a prospective, observational trial, we investigated the influence of time of day on the duration of neuromuscular blockade (NMB) elicited by rocuronium. Forty-nine patients scheduled for surgery between 08:00 and 02:00 were enrolled after giving written informed consent. Time to neuromuscular recovery was measured following three doses: (1) a fat-free-mass (FFM) related induction dose (0.6 mg x kg(-1): n = 47); (2) a maintenance dose (20% of the induction dose: n = 42); and (3) a standard 10-mg dose (n = 35). The extent of NMB was dependent on the time of administration (p = 0.038 General Linear Model Analysis). The maximum effect of 50 min (95% CI 41-59 min) was elicited between 08:00 and 11:00 and the minimum duration of 29 min (95% CI 23-35 min) between 14:00 and 17:00 (p = 0.005). A similar pattern was observed for the maintenance dose. The duration of action of rocuronium is influenced by time of day and this effect is of potential clinical significance and practical relevance to research.