A stochastic model for the evolution of a growing population is proposed, in order to explain empirical power-law distributions in the frequency of family names as a function of the family size. Preliminary results show that the predicted exponents are in good agreement with real data. The...

Diffusion of point defects is investigated as a possible origin of 1/f noise in a semiconductor; as an example, diffusion of donor atoms in a strongly extrinsic semiconductor is dealt with. Due to diffusion of donor atoms, the generation–recombination (g–r) process at a certain site may be...