Global cooling as a driver of diversification in a major marine clade

Climate is a strong driver of global diversity and will become increasingly important as human influences drive temperature changes at unprecedented rates. Here we investigate diversification and speciation trends within a diverse group of aquatic crustaceans, the Anomura. We use a phylogenetic framework to demonstrate that speciation rate is correlated with global cooling across the entire tree, in contrast to previous studies. Additionally, we find that marine clades continue to show evidence of increased speciation rates with cooler global temperatures, while the single freshwater clade shows the opposite trend with speciation rates positively correlated to global warming. Our findings suggest that both global cooling and warming lead to diversification and that habitat plays a role in the responses of species to climate change. These results have important implications for our understanding of how extant biota respond to ongoing climate change and are of particular importance for conservation planning of marine ecosystems

Lawson criterion for ignition exceeded in an inertial fusion experiment

For more than half a century, researchers around the world have been engaged in attempts to achieve fusion ignition as a proof of principle of various fusion concepts. Following the Lawson criterion, an ignited plasma is one where the fusion heating power is high enough to overcome all the physical processes that cool the fusion plasma, creating a positive thermodynamic feedback loop with rapidly increasing temperature. In inertially confined fusion, ignition is a state where the fusion plasma can begin "burn propagation" into surrounding cold fuel, enabling the possibility of high energy gain. While "scientific breakeven" (i.e., unity target gain) has not yet been achieved (here target gain is 0.72, 1.37 MJ of fusion for 1.92 MJ of laser energy), this Letter reports the first controlled fusion experiment, using laser indirect drive, on the National Ignition Facility to produce capsule gain (here 5.8) and reach ignition by nine different formulations of the Lawson criterion

Investigation of crossing and veering phenomena in an isogeometric analysis framework

The dynamic properties of crossing and veering in coupled structures have been studied both numerically and analytically, but they are difficult to investigate using Finite Element Analysis because of the change in the topological arrangement due to the different configuration. Isogeometric Analysis, recently developed method for numerical simulation, could overcome some of the drawbacks of the change in the configuration such as remeshing, coupling between the nodes of the different models, need of a fine mesh to allow small change in the configuration to be comparable to the mesh size. The key of this method is to avoid meshing and using the same basis functions used by the geometry, namely Non-Uniform Rational B-Splines (NURBS), to define the discretization of a Finite Element model. Other advantages are the possibility of increasing the order of the functions to obtain smooth stress field across the element interfaces. An experimental test-rig composed by beams and masses, which allow different configuration and dynamic coupling as well, is used as test case to validate the accuracy of the results with respect to both experimental data and classical Finite Element Analysis