Toxicity of Oil and Dispersed Oil on Juvenile Mud Crabs,Rhithropanopeus harrisii

In order to simulate an offshore oil spill event, we assessed the acute toxicity of the non-dispersed and the chemically dispersed water-accommodated fraction (WAF) of crude oil using Louisiana sweet crude and Corexit^® 9500A with juvenile Harris mud crabs (Rhithropanopeus harrisii), an important Gulf of Mexico benthic crustacean. The chemical dispersion of crude oil significantly increased acute toxicity of the WAF in juvenile mud crabs compared to naturally dispersed oil. The majority of the mortality in the chemically dispersed treatments occurred within 24 h. While higher concentrations of chemically dispersed WAF had no survivors, at lower concentrations surviving juvenile crabs displayed no long-term effects. These results suggest that if the juvenile crabs survive initial exposure, acute exposure to dispersed or non-dispersed crude oil may not induce long-term effects.     

Measuring the quantitative performance of surgical operating lists: theoretical modelling of 'productive potential' and 'efficiency'

We previously defined surgical list 'efficiency' as: maximising theatre utilisation, minimising over-running, and minimising cancellations. 'Efficiency' maximises output for input; 'productivity' emphasises total output. We define six criteria that any measure of productivity (better termed 'quantitative performance') needs to satisfy. We then present a theoretical analysis that fulfils these by incorporating: 'speed' of surgery (with reference to average speeds), 'patient contact' (synonymous with minimising gaps between cases), and 'efficiency' (as previously defined). 'Speed' and 'patient contact' together constitute a 'productive potential'. Our formula satisfies the pre-set criteria and yields plausible results in both hypothetical and real data sets, To be productive in these quantitative terms, teams in any specialty need to achieve minimum quality standards defined by their sub-specialty; to plan their lists to utilise the time available with no cancellations or over-runs and to work at least as fast as average with minimal gaps between cases. 'Productive potential' combined with 'efficiency' yielding 'actual productivity' in our theoretical analysis more completely describes quantitative surgical list performance than any other single measure.