Dynamical models for sand ripples beneath surface waves

We introduce order parameter models for describing the dynamics of sand ripple patterns under oscillatory flow. A crucial ingredient of these models is the mass transport between adjacent ripples, which we obtain from detailed numerical simulations for a range of ripple sizes. Using this mass transport function, our models predict the existence of a stable band of wavenumbers limited by secondary instabilities. Small ripples coarsen in our models and this process leads to a sharply selected final wavenumber, in agreement with experimental observations.Comment: 9 pages. Shortened version of previous submissio

Comparing safety culture and learning culture

This article examines the alignment of learning and safety culture in organisations. It tests the hypothesis that factors that indicate a good learning culture might also signify good safety and vice versa. The hypothesis was tested through an intensive literature review. Areas of alignment of learning culture and safety culture were identified. Six components of learning culture and safety culture can be measured by the same instrument. These components form guiding principles for measurement of safety culture and learning culture. Another eight component areas were identified where learning culture and safety culture partially align. Four further components were found to be relevant to either safety culture or learning culture and do not align. Overall, there is a relationship between learning culture and safety culture, but gauging one does not provide a reliable measure of the other