Many factors influence the near-field visualization of plasmonic structures that are based on perforated elliptical slits. Here, characterization errors are experimentally analyzed in detail from both fabrication and measurement points of view. Some issues such as geometrical parameter, probe-sample surface interaction, misalignment, stigmation, and internal stress, have influence on the final ...

For various graph-theoretic properties P that impose upper bounds on the minimum degree or the size of a neighbourhood set, we characterize the class %(P’) (%((P’)) of graphs G such that G and all its subgraphs (subcontractions) have property P. For example, if P is “6 <xn” (6 = minimum degree, n = number of vertices, 0 <X < 1) then S(P’) = F(K,+,), the class of graphs that do not have K,,, as ...

We study which infinite posets have simple cofinal subsets such as chains, or decompose canonically into such subsets. The posets of countable cofinality admitting such a decomposition are characterized by a forbidden substructure; the corresponding problem for uncountable cofinality remains open.