Cosmic Strings and Coherence
  Cosmic strings provide a radically different paradigm for the formation of structure to the prevailing inflationary one. They afford some extra technical complications: for example, the calculation of the power spectrum of matter and radiation perturbations requires the knowledge of the history of the evolution of the defects in the form of two-time correlation functions. We describe some numerical simulations of string networks, designed to measure the two-time correlations during their evolution. 
Mark Hindmarsh (1), Mairi Sakellariadou (2) and Graham R. Vincent (1)   ((1) Sussex University, (2) Universite de Geneve)