Levy flights in the space of mutations model time evolution of bacterial DNA. Parameters in the model are adjusted in order to fit observations coming from the Long Time Evolution Experiment with E. Coli.
We suggest a possible correlation between the ionization events caused by the background neutron radiation and the experimental data on mutations with damage in the DNA repair mechanism, coming from the Long Term Evolution Experiment in E. Coli populations.
The dynamics of small perturbations against the stationary density matrix of a pumped polariton system with only one photon polarization is studied. Depending on the way the system is pumped and probed, decay times ranging from 30 to 5000 ps are found. The large decay times under resonant pumping are related to a bottleneck effect in the decay of the excess (probe) populations of dark polariton states. No singular behaviour at the threshold for polariton lasing is observed.