Criteria for successful separation by continuous electrophoresis and electrochromatography in blocks and columns

By analysis of some important process variables, criteria for successful separation by continuous electrophoresis and electrochromatography in packed beds are derived. A general theory correlating power input, residence time and temperature rise in cylindrical and rectangular geometries is presented. The limitation of the separating capacity by transverse diffusion effects is shown to be predictable in terms of other operational conditions. These separation criteria appear to be in agreement with experimental evidence, and may find analytical as well as preparative application

Numerical study of the optical nonlinearity of doped and gapped graphene: From weak to strong field excitation

Numerically solving the semiconductor Bloch equations within a phenomenological relaxation time approximation, we extract both the linear and nonlinear optical conductivities of doped graphene and gapped graphene under excitation by a laser pulse. We discuss in detail the dependence of second harmonic generation, third harmonic generation, and the Kerr effects on the doping level, the gap, and the electric field amplitude. The numerical results for weak electric fields agree with those calculated from available analytic perturbation formulas. For strong electric fields when saturation effects are important, all the effective third order nonlinear response coefficients show a strong field dependence.Comment: 12 pages with 9 figure

Third order nonlinearity of graphene: effects of phenomenological relaxation and finite temperature

We investigate the effect of phenomenological relaxation parameters on the third order optical nonlinearity of doped graphene by perturbatively solving the semiconductor Bloch equation around the Dirac points. An analytic expression for the nonlinear conductivity at zero temperature is obtained under the linear dispersion approximation. With this analytic formula as starting point, we construct the conductivity at finite temperature and study the optical response to a laser pulse of finite duration. We illustrate the dependence of several nonlinear optical effects, such as third harmonic generation, Kerr effects and two photon absorption, parametric frequency conversion, and two color coherent current injection, on the relaxation parameters, temperature, and pulse duration. In the special case where one of the electric fields is taken as a dc field, we investigate the dc-current and dc-field induced second order nonlinearities, including dc-current induced second harmonic generation and difference frequency generation.Comment: 23+ pages, 10 figures. In this version we correct a sign typo in Eq. (25), for which we thank the discussion in the work http://arxiv.org/abs/1506.00534v

Crystallographic and magnetic structure of RbCoCl3 · 2 D2O

The crystallographic and magnetic structure of RbCoCl3 · 2 D2O were determined mainly by means of neutron diffraction measurements. Below TN = 2.79 K the magnetic moments are ordered in a canted antiferromagnetic pattern. A meta-magnetic phase transition is observed at unusually small field values (H = 18 Oe at T = 2 K)

Constructing a no-reference H.264/AVC bitstream-based video quality metric using genetic programming-based symbolic regression

In order to ensure optimal quality of experience toward end users during video streaming, automatic video quality assessment becomes an important field-of-interest to video service providers. Objective video quality metrics try to estimate perceived quality with high accuracy and in an automated manner. In traditional approaches, these metrics model the complex properties of the human visual system. More recently, however, it has been shown that machine learning approaches can also yield competitive results. In this paper, we present a novel no-reference bitstream-based objective video quality metric that is constructed by genetic programming-based symbolic regression. A key benefit of this approach is that it calculates reliable white-box models that allow us to determine the importance of the parameters. Additionally, these models can provide human insight into the underlying principles of subjective video quality assessment. Numerical results show that perceived quality can be modeled with high accuracy using only parameters extracted from the received video bitstream