Full Maxwell-Bloch equations are solved with PC-FDTD method to investigate population evolution of dense V-type three-level medium in few-cycle laser pulses.It is shown that the ratio of transition dipole moments(γ) has strong influence on appearing time and oscillation frequency of population inversion.As γ=1 population inversion with LFC appears later than that without LFC and near dipole-dipole(NDD) interaction delays population inversion.As γ>1,appearing with LFC is earlier than that without LFC and NDD interaction accelerates the population inversion.The number of population inversion with unequal transition dipole moments is more than that with equal transition dipole moments.Moreover,evolution of populations in a dense medium is quite different from that in a dilute medium.At input surface,in a dilute medium,population inversion appears with time evolution.With increasing of medium density,populations show quasi-periodicity oscillation and oscillation frequencies of populations with LFC are less than that without LFC.

A simplified off-lattice model of protein is studied with a PSO algorithm.Interaction between atoms is represented by a physical-based potential.The protein's RMSD value between computed and experimental structures is 6.12Å in optimizing the potential in global space. The protein total energy and radius of gyration at PSO steps and the relation between minimum energy and corresponding RMSD value are investigated.It shows basic characteristics of protein folding.