International Journal of Modern Physics B

Showing that the location of the zeros of the partition function can be used to study phase transitions, Yang and Lee initiated an ambitious and very fruitful approach. We give an overview of the results obtained using this approach. After an elementary introduction to the Yang–Lee formalism, we summarize results concerning equilibrium phase transitions. We also describe recent attempts and breakthroughs in extending this theory to nonequilibrium phase transitions.

We have thoroughly analyzed the electronic structure of stacked DNA Watson–Crick (WC) base pair dimers using ab initio Hartree–Fock and semiempirical Hartree–Fock-configuration-interaction quantum chemistry. We consider all the possible base compositions and sequences at the nucleoside level in vacuo. The results show that in such systems charge carrier generation could in principle be possible via charge transfer excitons, which turn out to dominate the first excited electronic states of the WC base pairs and their stacked dimers, and this process is largely sequence- and conformation-dependent. Possible consequences of this result for polymeric DNA duplexes are discussed.

The propagation characteristics of nonlinear TE surface waves at a lateral antiferromagnetic/nonmagnetic superlattices (LANS) substrate and a nonlinear magnetic cover have been investigated. LANS which are linear frequency-dependent gyromagnetic media, are described with an effective medium theory. It is found that the dispersion of the TE waves show the optical bistability behavior. The optical bistability is affected by the magnetic fraction f₁. We also calculate and illustrate the variation of the wave index with the power flow for various values of f₁. We found that the decrease in f₁ makes the power threshold of nonlinear TE surface waves decrease.

We have prepared Fe–Ni particles coated with 3 wt% SiO₂ by chemical synthesis. The precursor compounds have been reduced in hydrogen gas at different temperatures. The dependence of complex permeability μ on different reduction temperatures is studied by using an impedance analyzer. The experiment results indicate that the domain wall pinning strength, the average domain thickness and the resistivity depend on different heat treatment conditions. The magnetization process is mostly contributed by the domain wall bulging and displacement.

In this paper we consider the model of a flexible polymer chain embedded in a quenched random medium with long-range disorder correlations. Using the Feynman path integral approach we show that for the case of long-range quadratic correlations, we obtain an analytical result. The result is , where 〈R²〉 is the mean square end-to-end distance of the polymer chain, ξ is the correlation length of disorder, Δ is an unknown parameter, b is the Kuhn step length, ρ is the density of random obstacles and N is the number of links. It is shown that for a polymer chain in a random media with long-range quadratic correlations, where ρ is not too high, the behavior of the polymer chain is like that of a free chain. This result agrees with the calculation using the replica method. However, in a medium where ρ is very high, the variation of the mean square end-to-end distance with disorder and its distance depending on ρ are found in our approach.

In this paper, we propose an observer-based synchronization scheme for piecewise-linear discrete chaotic systems based on piecewise quadratic Lyapunov functions. Firstly, due to the properties of piecewise-linear discrete chaotic systems, we use a switching observer for state synchronization. Then, we derive a sufficient condition represented by linear matrix inequalities (LMIs) for global asymptotic synchronization. Finally, we give some numerical simulations to demonstrate the effectiveness of our theoretical results.