The performance of several common approximations for the exchange-correlation kernel within time-dependent density-functional theory is tested for elementary excitations in the homogeneous electron gas. Although the adiabatic local-density approximation gives a reasonably good account of the plasmon dispersion, systematic errors are pointed out and traced to the neglect of the wavevector depend...

The effect of sonication temperature on the debundling of carbon nanotube (CNT) macro-bundles is reported and demonstrated by analysis with different particle sizing methods. The change of bundle size over time and after several comparatively gentle sonication cycles of suspensions at various temperatures is reported. A novel technique is presented that produces a more homogeneous nanotube disp...

242 A dispersion are considered to be the dominant mechanisms of solute transport in the vadose zone, i.e., the variably saturated layer of soils and sediments between the soil surface and groundwater table (Jury and Flühler, 1992). Advection is associated with the average water fl ux or velocity, whereas hydrodynamic dispersion is modeled using an analog of Fick’s law corresponding to the Brow...

Internet firms charge a wide range of prices for homogeneous products, and high-priced firms remain high-priced and low-priced firms remain low-priced over long periods. One explanation is that high-price firms are charging a premium for superior service. An alternative, price-dispersion explanation is that firms vary the prices for informed and uniformed consumers (Salop and Stiglitz, 1977) or...

Previous statistical tests showed that call center arrival data were consistent with a non-homogeneous Poisson process (NHPP) within each day, but exhibit over-dispersion over multiple days. These tests are applied to arrival data from an endocrinology clinic, where arrivals are by appointment. The clinic data are also consistent with an NHPP within each day, but exhibit under-dispersion over m...

The issue of the nanocomposites’ synthesis using aluminum matrixes, reinforced with carbon nanotubes, high physical and mechanical performance capabilities, as related to achieving homogeneous dispersion nanotubes in composite’s matrix has been considered. Basics preparation technology have developed requirements for parameters so-called «normalized» mixture (highly-homogeneous terms volume dry...

Let us consider the following problem. Imagine a homogeneous nonlinear medium in which only one type of wave with dispersion law co(k) may propagate. Let the nonlinearity of the medium be quadratic while the equation co(k~ + k~) = co(k0 + co(k2) (1) defines a nonzero manifold F whose codimension in kl, k2 space is unity. Equation (1) means that dispersion law co(k) allows decay processes. The n...

A deterministic multiscale dynamical system is introduced and discussed as a prototype model for relative dispersion in stationary, homogeneous, and isotropic turbulence. Unlike stochastic diffusion models, here trajectory transport and mixing properties are entirely controlled by Lagrangian chaos. The anomalous "sweeping effect," a known drawback common to kinematic simulations, is removed thr...