Color superconductivity vs. pseudoscalar condensation in a three-flavor NJL model

We calculate numerically the phase diagram of the three-flavor Nambu-Jona-Lasinio model at zero and finite temperature as a function of the up, down, and strange quark chemical potentials. We focus on the competition between pseudoscalar condensation and color superconductivity. We find that the two types of phases are separated by first-order transitions.Comment: 8 pages, 7 figures, revtex. References added, minor other changes, conclusions unchanged. To appear in PR

Wild Collection and Cultivation of Native Species in Iceland

Based on an MSc thesis submitted to the joint Master program between University of Kassel and University of Goettingen and later published: WHITNEY C.W., GEBAUER J. & ANDERSON M. 2012. A Survey of Wild Collection and Cultivation of Indigenous Species in Iceland. Human Ecology. This paper outlines a survey of Icelanders who use local plants. Some of the species (e.g. Angelica spp. and Betula spp.) were very important. However, great potential exists for a more diverse harvest and for sustainable management (e.g. Organic certification). There is also potential for the spreading native plant use knowledge and the inherent associated conservation culture. The data also suggests that cultural conservation should focus on food, which appears to be paramount in increasing the cultural importance of a plant

Strong scaling of general-purpose molecular dynamics simulations on GPUs

We describe a highly optimized implementation of MPI domain decomposition in a GPU-enabled, general-purpose molecular dynamics code, HOOMD-blue (Anderson and Glotzer, arXiv:1308.5587). Our approach is inspired by a traditional CPU-based code, LAMMPS (Plimpton, J. Comp. Phys. 117, 1995), but is implemented within a code that was designed for execution on GPUs from the start (Anderson et al., J. Comp. Phys. 227, 2008). The software supports short-ranged pair force and bond force fields and achieves optimal GPU performance using an autotuning algorithm. We are able to demonstrate equivalent or superior scaling on up to 3,375 GPUs in Lennard-Jones and dissipative particle dynamics (DPD) simulations of up to 108 million particles. GPUDirect RDMA capabilities in recent GPU generations provide better performance in full double precision calculations. For a representative polymer physics application, HOOMD-blue 1.0 provides an effective GPU vs. CPU node speed-up of 12.5x.Comment: 30 pages, 14 figure