Scaling properties of the Penna model

We investigate the scaling properties of the Penna model, which has become a popular tool for the study of population dynamics and evolutionary problems in recent years. We find that the model generates a normalised age distribution for which a simple scaling rule is proposed, that is able to reproduce qualitative features for all genome sizes.Comment: 4 pages, 4 figure

The Coester Line in Relativistic Mean Field Nuclear Matter

The Walecka model contains essentially two parameters that are associated with the Lorentz scalar (S) and vector (V) interactions. These parameters are related to a two-body interaction consisting of S and V, imposing the condition that the two-body binding energy is fixed. We have obtained a set of different values for the nuclear matter binding energies at equilibrium densities. We investigated the existence of a linear correlation between $B_N$ and $\rho_0$, claimed to be universal for nonrelativistic systems and usually known as the Coester line, and found an approximate linear correlation only if $V?S$ remains constant. It is shown that the relativistic content of the model, which is related to the strength of $V?S$, is responsible for the shift of the Coester line to the empirical region of nuclear matter saturation.Comment: 7 pages, 5 figure

Categorical Groups, Knots and Knotted Surfaces

We define a knot invariant and a 2-knot invariant from any finite categorical group. We calculate an explicit example for the Spun Trefoil.Comment: 40 pages, lots of figures. Second version: Added example and discussion, clarification of the fact that the maps associated with Reidemeister Moves are well define