We use the variational method to find the optimum launch conditions that can sustain path-averaged solitons in a periodically amplified, constant-dispersion, optical communication system even when amplifier spacing is comparable to or larger than the dispersion length. We determine the amount of prechirping and the initial peak power required and show that both the pulse width and the chirp rec...

Two efficient unconditionally-stable four-stages splitstep (SS) finite-difference time-domain (FDTD) methods based on controlling parameters are presented, which provide low numerical dispersion. Firstly, in the first proposed method, the Maxwell’s matrix is split into four sub-matrices. Simultaneously, two controlling parameters are introduced to decrease the numerical dispersion error. Accord...

In this study a solid dispersion and a physical mixture of cilazapril (CIL) with a biopolymer - polyvinylpyrrolidone (PVP) as a carrier were prepared so as to investigate the effect of PVP on the stability of CIL. CIL is unstable in solid state and decomposes rapidly under humid conditions. It requires stabilization to ensure safety of its use. The studied CIL/PVP formulations were prepared by ...

In this study a solid dispersion and a physical mixture of cilazapril (CIL) with a biopolymer - polyvinylpyrrolidone (PVP) as a carrier were prepared so as to investigate the effect of PVP on the stability of CIL. CIL is unstable in solid state and decomposes rapidly under humid conditions. It requires stabilization to ensure safety of its use. The studied CIL/PVP formulations were prepared by ...

An optimized explicit modified Runge-Kutta RK method for the numerical integration of the radial Schrödinger equation is presented in this paper. This method has frequency-depending coefficients with vanishing dispersion, dissipation, and the first derivative of dispersion. Stability and phase analysis of the new method are examined. The numerical results in the integration of the radial Schröd...

In this paper, we consider a Riesz space-fractional reaction-dispersion equation (RSFRDE). The RSFRDE is obtained from the classical reaction-dispersion equation by replacing the second-order space derivative with a Riesz derivative of order β ∈ (1,2]. We propose an implicit finite difference approximation for RSFRDE. The stability and convergence of the finite difference approximations are ana...

We present a three-dimensional finite-difference time-domain (FDTD) algorithm to minimize the numerical dispersion error at preassigned angles. Filtering schemes are used to further optimize its frequency response for broad-band simulations. A stability analysis of the resulting FDTD algorithm is also provided. Numerical results show that the dispersion error around any preassigned angle can be...

A theory of optical pulse propagation in cascaded transmission systems that are based on the dispersioncompensatingfiber technique is developed. The existence of two scales associated with fiber dispersion and system residual dispersion leads to a simple model for the averaged pulse dynamics. In the particular case of practical importance, the averaged pulse dynamics is governed by the nonlinea...

how to cite this article: movahedian ah, heidarzadeh arani m, motaharizad m, mousavi gha, mosayebi z. evaluation of qt dispersion in children with breath holding spells. iran j child neurol. winter 2016; 10(1):25-30. abstract objective breath holding spells (bhs) are common involuntary reflexes in infancy and early childhood. differential diagnosis should embrace long qt syndrome (lqts) and par...