Historical changes of the Mediterranean Sea ecosystem: modelling the role and impact of primary productivity and fisheries changes over time.

The Mediterranean Sea has been defined "under siege" because of intense pressures from multiple human activities; yet there is still insufficient information on the cumulative impact of these stressors on the ecosystem and its resources. We evaluate how the historical (1950-2011) trends of various ecosystems groups/species have been impacted by changes in primary productivity (PP) combined with fishing pressure. We investigate the whole Mediterranean Sea using a food web modelling approach.

The role of impulse on the initiation of particle movement under turbulent flow conditions.

Fundamental to our understanding of erosional and transport phenomena in earth-surface dynamics and engineering is knowledge of the conditions under which sediment motion will begin when subjected to turbulent flow. The onset criterion currently in use emphasizes the time-averaged boundary shear stress and therefore is incapable of accounting for the fluctuating forces encountered in turbulent flows. We have validated through laboratory experiments and analytical formulation of the problem a criterion based upon the impulse imparted to a sediment grain.