Liu Liang-Gang

A Microscopic Mechanism for Muscle Motion

We study the stochastic inclined rod model in a system with different complex potentials and discuss the effect of the spring on the system. The results of the calculation show that the spring, the effective radius of the G-actin and the intermolecular potential play key roles in the motion. The sliding speed is about 4.7×10-6m/s calculated from the model which well agrees with the experimental data.

Noise in Genotype Selection Model

We study the steady state properties of a genotype selection model in presence of correlated Gaussian white noise. The effect of the noise on the genotype selection model is discussed. It is found that correlated noise can break the balance of gene selection and induce the phase transition which can makes us select one type gene haploid from a gene group.

Automatic Estimation of Peak Regions in Gamma-Ray Spectra Measured by NaI Detector

We present an approach to estimate the width of peak regions for the background elimination of gamma ray spectrum. The synthetic and experimental data are used to test this method. With the estimated peak regions using the proposed method in the whole spectra, we find that the approach is simple and effective enough for the background elimination cooperating with the statistics-sensitive nonlinear iterative peak-clipping method.

Muscle's Motion in an Overdamped Regime*

Based on the stochastic inclined rods model proposed by H. Matsuura et al., we study the motion of actin myosin system in an overdamped regime. Our model is composed of an inclined spring (rod), a myosin head and a myosin filament. The results of calculation show that the model can convert the random motion to one-directional motion, and the myosin head works as a resonator of random noise, which absorbs the energy through a stochastic resonance. The results show that the inclined rod and the intermolecular potential are very important for the system to move.

Tachyon Pole in σ Meson Propagator in Nuclear Matter in the Relativistic σ-ω Model*

The conditions that the tachyon pole of the σ meson propagator in nuclear matter appears are studied in the one-loop approximation in the relativistic the σ-ω model. Different from the results of the previous paper, we find that the effect of the constant the a in the self-interaction, , of the σ meson cannot be neglected. It determines the critical density where tachyon appears. The smaller the a, the larger the critical density. The binding energy, pressure, incompressibility coefficient, nucleon effective mass are calculated and the relation between parameters to the tachyon pole is also studied.

Structural and Spacial Characters of Neutron Star in Relativistic σ–ω Model

The analytical and numerical solutions of structure and curvature of two kinds of static spherically symmetric neutron stars are calculated. The results show that Ricci tensor and curvature scalar cannot denote the curly character of the space directly, however, to static spherically symmetric stars, these two quantities can present the relative curly degree of the space and the matter distribution to a certain extent.

Influence of Hyperon on 1S0 Superfluidity of Nucleons in Neutron Star Matter

We investigate the property of 1S0 superfluidity of neutrons and protons in the neutron star matter. On the basis of the result, we study the effects of hyperons on the 1S0 pairing gaps of the two species of the particles. The parameter sets we use are for the Hartree approximation of the relativistic σ−ω model and the mean field approximation of the Walecka model, respectively. The predicted domain of superfluidity is very close to other works, whereas differences appear in the predicted value of the maximum gap. It is found that Σ−, Λ and Ξ− have some influences, the scales of which depend on hyperon-meson coupling constants we use besides other factors, on the 1S0 superfluidity of protons in some density range, and do not have influence on superfluidity of neutrons. Other hyperons have no influence on the 1S0 superfluidity of neutron and proton due to these hyperons appearing after 1S0 neutron and proton pairs disappear.

Fluctuation of Parameters in Tumor Cell Growth Model

We study the steady state properties of a logistic growth model in the presence of Gaussian white noise. Based on the corresponding Fokker-Planck equation the steady state solution of the probability distribution function and its extrema have been investigated. It is found that the fluctuation of the tumor birth rate reduces the population of the cells while the fluctuation of predation rate can prevent the population of tumor cells from going into extinction. Noise in the system can induce the phase transition.

Current Reversal Due to Coupling Between Asymmetrical Driving Force and Ratchet Potential

Transport of a Brownian particle moving in a periodic potential is investigated in the presence of an asymmetric unbiased external force. The asymmetry of the external force and the asymmetry of the potential are the two ways of inducing a net current. It is found that the competition of the spatial asymmetry of potential with the temporal asymmetry of the external force leads to the phenomena like current reversal. The competition between the two opposite driving factors is a necessary but not a sufficient condition for current reversals.

Effects of Cross-Correlation Colour Noises on Tumour Growth Process

We present a tumour cell growth process model including a multiplicative coloured noise and an additive coloured noise correlated. How the noise cross-correlation intensity λ and correlation time τ can affect the steady state properties of tumour cell growth model are discussed by solving an approximative Fokker–Planck equation. It is found that the increase of noise correlation time τ can cause the tumour cell number increasing, but the increase of multiplicative noise intensity can cause the tumour cell number extinction. We also find that the increase of cross-correlation intensity λ in the case of 0<λ<1 can cause the tumour cell number extinction, whereas increase of cross-correlation intensity λ in the case of λ<0 can cause the tumour cell number increasing.