Modern Physics Letters B

A theoretical review of optical spin injection for bulk semiconductors is presented. As an example, we calculated such response in bulk Si, GaAs and CdSe. For each of these systems the computation of the electronic wavefunctions and energies are obtained under the density functional theory (DFT) within the local density approximation (LDA).

The central oblique collision efficiency of spherical nanoparticles in the Brownian coagulation is studied. A new model of central oblique collision between two spherical nanoparticles is proposed to build equations which are solved to get the collision efficiency for the monodisperse dioctyl phthalate nanoparticle with diameter changing from 100 to 800 nm in the presence of Van der Waals force and elastic deformation force. The calculated results are in agreement with the experimental data qualitatively. The results show that the interparticle elastic deformation force cannot be neglected when dealing with particle Brownian coagulation. The collision efficiencies for the central normal collision and central oblique collision are different obviously. A set of new formulas relating central oblique collision efficiency to particle diameter is put forward.

The cell membrane is an important organ of living cells, which has a complex structure influenced by the interaction between membrane proteins and cell membrane. On the basis of fluid motion and diffusion interaction, a simple model is proposed to evaluate quantitatively the effects of the protein size and membrane fluid velocity on the lateral diffusion of membrane proteins at the cell membrane. The study shows that the diffusion coefficient is a dominant factor on the lateral diffusion.

The daily streamflow series of three rivers are analyzed from the view of complex networks, i.e. the Yangtze River in China, the Umpqua River and the Ocmulgee River in the United States. We construct networks from these series by using the visibility graph algorithm respectively. The degree distribution and accumulative degree distribution are investigated. We find that the degree distribution of the Umpqua River series network, the Ocumlgee River series network and the subsequence of the Yangtze River series network can be better fitted by stretched exponential distribution (SED), although the degree distribution curves of these networks in a log–log plot have a linear part. Moreover, the slope α of the linear part and parameters μ in SED have significant meaning in the research of streamflow series properties.

The simple efficiency model is developed on scale-free networks with communities to study the effect of the communities in complex networks on efficiency dynamics. For some parameters, we found that the state of system will transit from a stagnant phase to a growing phase as the strength of community decreases.

Many practical systems in physical and biological sciences have impulsive dynamical behaviors during the evolution process which can be modeled by impulsive differential equations. In this paper, the approximate controllability of nonlinear second-order stochastic infinite-dimensional dynamical systems with impulsive effects is considered. By using the Holder's inequality, stochastic analysis and fixed point strategy, a new set of necessary and sufficient conditions are formulated which guarantees the approximate controllability of the nonlinear second-order stochastic system. The results are obtained under the assumption that the associated linear system is approximately controllable.

Using a 4-dimensional Lie algebra g, an isospectral Lax pair is introduced, whose compatibility condition is equivalent to a soliton hierarchy of evolution equations with three components of potential functions. Its Hamiltonian structure is obtained by employing the quadratic-form identity proposed by Guo and Zhang. In order to obtain explicit Hamiltonian functions, a detailed computing formula for the constant appearing in the quadratic-form identity is obtained. One type of reduction equations of the hierarchy is also produced, which is further reduced to the standard equation of heat conduction. By introducing a loop algebra of the Lie algebra g, we obtain a soliton hierarchy with an arbitrary parameter which can be reduced to the previous equation hierarchy obtained, whose quasi-Hamiltonian structure is also worked out by the quadratic-form identity. Finally, we extend the Lie algebra g into a higher-dimensional Lie algebra so that a new integrable Hamiltonian hierarchy, which comprise integrable couplings, is produced; its reduced equations in particular contain two arbitrary parameters.

Let X be a separable metric space containing at least two points, and f:X→X be continuous. In this paper, we consider dynamical systems on X, and prove that topologically weakly mixing implies distributional chaos in a sequence.

Theoretical isotropic (spherically symmetric) Compton profiles (ICP) have been calculated for many particle systems' He, Li, Be and B atoms in their ground states. Our calculations were performed using Roothan–Hartree–Fock (RHF) wave function, HF wave function of Thakkar and re-optimized HF wave function of Clementi–Roetti, taking into account the impulse approximation. The theoretical analysis included a decomposition of the various intra and inter shells and their contributions in the total ICP. A high momentum region of up to 4 a.u. was investigated and a non-negligible tail was observed in all ICP curves. The existence of a high momentum tail was mainly due to the electron–electron interaction. The ICP for the He atom has been compared with the available experimental data and it is found that the ICP values agree very well with them. A few low order radial momentum expectation values 〈pⁿ〉 and the total energy for these atomic systems have also been calculated and compared with their counterparts' wave functions.