The paper outlines a case study of US Ecommerce over the past 5 years. The case describes key factors that position the US for leadership in the realm of global Ecommerce, while pointing out inherent risk areas that could threaten this position. It does so utilizing a list of drivers and inhibitors as the basis for analysis in the context of an overview of the US National Environment; its inher...

We have studied the mechanism by which dispersed Y 2 0 3 exerts beneficial effects on the oxidation protection of an A1203 coating (film) on the basis of the following models: 1) Y2O3 suppresses surface segregation of S by trapping it in the alloy matrix and accordingly suppresses spalling of the A1203 film; 2.1) The diffusion of alloying elements into the N2o3 film is retarded by dispersed oxi...

Gradual transitions in index of refraction from layer to layer, as in rugate coatings, can be advantageous. When absorption or the k-value is negligible, it can be shown that the first order reflection band is not significantly changed from when the transition between layers is “square” even to the case where it is sinusoidal. In most visible spectrum cases, the difference between the indices o...

We present a first-principles analysis of the strain renormalization of the cation diffusivity on the GaAs(001) surface. For the example of In/GaAs(001)-c(4 × 4) it is shown that the binding of In is increased when the substrate lattice is expanded. The diffusion barrier ∆E(ε) has a non-monotonic strain dependence with a maximum at compressive strain values (ε < 0), while being a decreasing fun...

In mammalian neurons, the precise accumulation of sodium channels at the axonal initial segment (AIS) ensures action potential initiation. This accumulation precedes the immobilization of membrane proteins and lipids by a diffusion barrier at the AIS. Using single-particle tracking, we measured the mobility of a chimeric ion channel bearing the ankyrin-binding motif of the Nav1.2 sodium channel...

We investigate the effect of nitrogen and boron doping on Li diffusion through defected graphene using first principles based density functional theory. While a high energy barrier rules out the possibility of Li- diffusion through the pristine graphene, the barrier reduces with the incorporation of defects. Among the most common defects in pristine graphene, Li diffusion through the divacancy ...

We analyze diffusion in a finite domain with a position-dependent diffusion coefficient in terms of a stochastic hopping process. Via a coordinate transformation, we map the original system onto a problem with constant diffusion but nontrivial potential. In this way we show that a regime with enhanced diffusion acts as a potential barrier. We compute first-passage time distributions, hopping ra...

We have used density-functional theory and the nudged elastic-band method to calculate migration pathways and estimated the activation energy for the diffusion of oxygen vacancies in a-quartz. While the energy barrier for the diffusion of a neutral vacancy is very high, 4.1 eV, the binding of a triplet-state exciton to the vacancy lowers the barrier to 1.7 eV and the attachment of a hole lowers...