A first-principles study has been performed to evaluate the electronic and optical properties of wurtzite Zn<Subscript>1-x</Subscript>Mg<Subscript>x</Subscript>O. Substitutional doping is considered with Mg concentrations of x=0, 0.0625, 0.125, 0.1875 and 0.25, respectively. Mg incorporation can induce band gap widening due to the decrease...</subscript></subscript>

The spin-states of cobalt based perovskite compounds depend sensitively on the valence state and local crystal environment of Co ions and the rich physical properties arise from strong coupling among charge, spin, and orbital degrees of freedom. While extensive studies have been carried out in...

We study the propagation of electromagnetic wave in piezoelectric period-doubling superlattices with using the generalized 4 × 4 transfer matrix method, and the dynamics of electromagnetic wave and acoustic wave is treated on equal footing. The band-gap structure trifurcates, which is...

In this paper, we develop various calculus rules for general smooth matrix-valued functions and for the class of matrix convex (or concave) functions first introduced by Loewner and Kraus in 1930s. Then we use these calculus rules and the matrix convex function -log X to study a new notion of...

The recent meltdown in some Asian economies highlights the urgent need of more proper measures of economic performance. Measures such as GNP growth rates alone are not good enough in revealing the true strength of an economy unless costs of capitals are also examined. In recent years, there have...

In this paper we introduce robust versions of the classical static and dynamic single leg seat allocation models as analyzed by Wollmer, and Lautenbacher and Stidham, respectively. These robust models take into account the inaccurate estimates of the underlying probability distributions. As...

The present paper proposes a new approach to solve generalized fractional programming problems through user interaction. Capitalizing on two alternatives, we review the Dinkelbach-type methods and set forth the main difficulty in applying these methods. In order to cope with this difficulty, we...

In this note we give a short and easy proof of the equivalence of Hakimi's one-median problem and the k-server-facility-loss median problem as discussed by Chiu and Larson in Computer and Operation Research. The proof makes only use of a stochastic monotonicity result for birth and death...