Evidence for the impact of global warming on the long-term population dynamics of common birds by Dr R Julliard, Dr F Jiguet and Dr D Couvet
We compared common birds' productivity (proportion of juveniles from standardised samples for 32 species, totalling over 50,000 captured individuals within 60 sites spread over France) between spring 2003, an exceptionally warm spring in France, and previous years. Productivity in 2003 was relatively low for already declining species while it was relatively good for increasing species. This adds evidences that climate warming plays a key role in the long term dynamics of even the commonest species. This further suggests that ability to reproduce in warmer and warmer conditions is a key component of species sensitivity to climate change.
Contact: Dr Romain Julliard, CRBPO-Museum National d'Histoire Nat., 55 rue Buffon, PARIS, F-75005, France
Proceedings of The Royal Society A: Mathematical, Physical and Engineering
On the distribution of elastic forces in disordered structures and materials. I Computer simulation by Dr AHW Ngan
Many engineering materials designed to cushion impacts (eg granular packings and foam materials) have random internal structures. When these materials are subjected to external loading, the internal forces are not uniform but distributed in a particular way because of this structural randomness. Understanding such force distributions is crucial for the prediction of the failure condition of these materials. This study shows that the force distributions can be accurately described by an analogue of the Second Law of Thermodynamics, which governs the directions of changes in thermal systems such as chemical reactions. In thermal systems the balance between the two fundamental driving forces of energy and entropy governs the directions of the changes. The same balance between energy and entropy, which measures disorder, governs the force di
Contact: Tim Watson