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Biomedical subjects

R Donangelo

Publications and source records attributed to R Donangelo.

At least 19 recordsLinked to original sources
PubMed2002

Model for mutation in bacterial populations.

We describe the evolution of E. coli populations through a Bak-Sneppen-type model which incorporates random mutations. We show that, for a value of the mutation level which coincides with the one estimated from experiments, this model reproduces the measures of mean fitness relative to that of a common ancestor, performed for over 10,000 bacterial generations.

Biological Evolution↗
PubMed2002

Dynamical localization in quasiperiodic driven systems.

We investigate how the time dependence of the Hamiltonian determines the occurrence of dynamical localization (DL) in driven quantum systems with two incommensurate frequencies. If both frequencies are associated to impulsive terms, DL is permanently destroyed. In this case, we show that the evolution is similar to a decoherent case. On the other hand, if both frequencies are associated to smooth driving functions, DL persists although on a time scale longer than in the periodic case. When the driving function consists of a series of pulses of duration sigma, we show that the localization time increases as sigma(-2) as the impulsive limit, sigma-->0, is approached. In the intermediate case, in which only one of the frequencies is associated to an impulsive term in the Hamiltonian, a transition from a localized to a delocalized dynamics takes place at a certain critical value of the strength parameter. We provide an estimate for this critical value, based on analytical considerations. We show how, in all cases, the frequency spectrum of the dynamical response can be used to understand the global features of the motion. All results are numerically checked.

Journal Article↗