(C) 2011 American Institute of Physics. [doi:10.1063/1.3642980]“
“Niche construction is the process by which organisms construct important components of their local environment in ways that introduce novel selection pressures. Lactase persistence is one of the clearest examples of niche construction in humans. Lactase is the enzyme responsible for the digestion of the milk sugar lactose and its production decreases after the weaning phase in most mammals, including most humans. Some humans, however, continue to produce lactase throughout adulthood, a trait known as lactase persistence. In European populations, a single mutation

(-13910*T) explains the distribution of the phenotype, whereas several mutations are Duvelisib in vitro associated with it in Africa

and the Middle East. Current estimates for the age of lactase persistence-associated alleles bracket those for the origins of animal domestication and the culturally transmitted practice of dairying. We report new data on the distribution of -13910*T and summarize genetic studies on the diversity of lactase persistence worldwide. We review relevant archaeological data and describe three simulation studies that have shed light on the evolution of this trait in Europe. These studies illustrate how genetic and archaeological information can be integrated to bring new insights to the origins and spread LY2835219 of lactase persistence. Finally, we discuss possible improvements to these models.”
“The nonisothermal crystallization behavior of Copper/low-density polyethylene (LDPE) nanocomposites was investigated by differential scanning calorimetry Erastin (DSC). The nanocomposites were prepared by solution blending method,

and the traditional extrusion melt method was also employed for comparison. The DSC results show that under identical copper content condition, the crystallization of the LDPE is facilitated owing to the higher degree of molecular regularity and the lesser chain entanglement for the nanocomposites prepared by the solution blending method in comparison with the traditional extrusion melt method. The differences of nonisothermal crystallization behavior diminish with the increasement of copper content between the nanocomposites prepared by the two methods. SEM/EDX was applied to study the dispersion of copper nanoparticles in the nanocomposites, and the results illustrate that the dispersion condition can be better when the solution blending method was employed. The investigation of the effective activation energy on the relative extent crystallization implies that the agglomeration of copper nanoparticles can facilitate the crystallization of the LDPE, while the well-dispersed copper nanoparticles act as obstacles since the motion of the LDPE molecular chains is limited. (C) 2011 Wiley Periodicals, Inc.