Statistical fluctuations in a saturation laser model with correlated noises

We study the effects of correlations between quantum and pump noises on fluctuations of the laser intensity in a saturation laser model. An approximative Fokker-Planck equation and analytic expressions of the steady-state probability distribution function （SPD） of the laser system are derived. Based on the SPD, the normalized mean, the normalized variance, and the normalized skewness of the steady-state laser intensity are calculated numerically. The results indicate that （i） the correlation strength A of correlated noises always enhances the fluctuation of laser intensity; （ii） the correlation time v of correlated noises strengthens the fluctuation of laser intensity for the below-threshold case but τ weakens it for the above-threshold case.

Effects of an electromagnetic field on intracellular calcium oscillations in a cell with external noise

Intracellular calcium ion concentration oscillation in a cell subjected to external noise and irradiated by an electromagnetic field is considered. The effects of the intensity E0, the polar angle θ and the frequency w of the external electric field on steady-state probability distribution and the mean Ca2＋ concentration, respectively, are investigated by a numerical calculation method. The results indicate that （i） variation of w cannot affect the intracellular calcium oscillation; （ii） the steady-state probability distribution presents a meaningful modification due to the variations of E0 and 0, while variation of 0 does not affect the steady-state probability distribution under the condition of a small E0, and E0 cannot affect the steady-state probability distribution either when θ=π/2; （iii） the mean Ca2＋ concentration increases as E0 increases when θ〈π/2 and, as 0 increases, it first increases and then decreases. However, it does not vary with E0 increasing when θ=π/2, but it increases with 0 increasing when E0 is small.

Coexistence and fluctuations phenomena with Davidson-like potentials in quadrupoleoctupole deformed nuclei

The energy spectra of three types of two-dimensional potentials(we will call them‘Davidson-like potentials’(DLPs)),characterized by four minima separated by barriers,are investigated.The predictions for spectra and wave functions are obtained by using the nine-point finite-difference method.For these potentials,with the existence of a single configuration,a transition of spectra,as a function of barrier height,is covered from tunneling splitting modes to fluctuations phenomena,with equal peaks wave functions,crossing to the spectra of purely anharmonic oscillator potentials(AOPs).A different type of phase transition occurs when two(or more)configurations coexist.With the change of the parameters,a transition of spectra is covered from coexistence phenomena of two distinct quantum tunneling modes to fluctuations phenomena,with unequal peaks wave functions,crossing to the spectra of purely AOPs.Using DLPs,a particular application of the coherent quadropole-octupole model to describe energy bands with alternating parity of the nuclei^(100)Mo,^(146,148)Nd,^(148,150)Sm,^(220)Ra,^(220,222)Rn,and^(220,222)Th is presented.The global parametrization of the model for the selected nuclei is achieved.