Looking for energy in demographic data; how to detect self-organization   in human population distribution
  In the present work we study the relationship between population allocation and the combined effects of urban size and energy consumption, for two given areas and through a major part of the twentieth century. Along these lines a general application model is laid down which relates city-growth rates to initial inhabitants and to exosomatic energy increment, the deviations from it showing order in space and time; as shown in a series of maps which hint at unaccounted socioeconomic factors. The study of the maps by means of spectral analysis allows finding patterns which reinforce over time, in such a manner that spatial frequencies can be determined whose weight increases up so granting surface evolution estimation. 
Josep M Casas-Busquet and Agust\'i Poch-Par\'es
physics.soc-ph q-bio.PE