Castilla elastica (Nahuatl) word for rubber was "ulli / olli", from which their word for the ballgame derived), and also their name for the ancient people they associated with the origin of the ballgame, the Olmecs ("olmeca": "rubber people"). The Nahuatl word for the tree of "Castilla elastica" is olicuáhuitl; in Spanish it is known as palo de hule. Caucho, castilloa rubber. Castilla elastica Castilla elastica, the Panama rubber tree, is a tree native to the tropical areas of Mexico, Central America, and northern South America. It was the principal source of latex among the Mesoamerican peoples in pre-Columbian times. The latex
Fermi liquid theory involve, e.g., a change in the effective mass of particles. The quadratic terms correspond to a sort of "mean-field" interaction between quasiparticles, which is parametrized by so-called Landau Fermi liquid parameters and determines the behaviour of density oscillations (and spin-density oscillations) in the Fermi liquid. Still, these mean-field interactions do not lead to a scattering of quasi-particles with a transfer of particles between different momentum states. The renormalization of the mass of a fluid of interacting fermions can be calculated from first principles using many-body computational techniques. For the two-dimensional homogeneous electron gas, GW calculations and quantum Monte Carlo methods