ZEITSCHRIFT FUR PHYSIK C-PARTICLES AND FIELDS, cilt.63, sa.4, ss.655-657, 1994 (SCI-Expanded)
We have introduced the finite size effects due to the spatial configuration of strings into the thermodynamical treatment of a system of strings in a way parallel to the one in polymer physics and showed that no singularity arises. At lower temperatures and densities strings are in a Brownian phase, then display a phase transition just above the Hagedorn temperature and go into a dense phase which is similar to the collapse phase in polymers. A string system can therefore exist at all temperatures.