We theoretically analyze the influence of the Gouy phase shift on the nonlinear interaction between waves of different frequencies. We focus on chi((2))interaction of optical fields, e.g. through birefringent crystals, and show that focussing, stronger than suggested by the Boyd-Kleinman factor, can further improve nonlinear processes. An increased value of 3.32 for the optimal focussing parame...

We introduce a parallel thinning algorithm with directional substeps based on the collapse operation, which is guaranteed to preserve topology and to provide a thin result. Then, we propose two variants of a surface-preserving thinning scheme, based on this parallel directional thinning algorithm. Finally, we propose a methodology to produce filtered surface skeletons, based on the above thinni...

Kinetic theory is used to describe pressure induced magnetic island formation in three-dimensional configurations. The kinetic responses describes currents that arise at rational surfaces that oppose the island producing magnetohydrodynamic (3-D) effects in general 3-D MHD equilibria. The kinetic response is largest at lowest collisionality suggesting that high-β stellarators are more resilient...

We study the equilibrium configuration of a nematic liquid crystal bounded by a rough surface. The wrinkling of the surface induces a partial melting in the degree of orientation. This softened region penetrates the bulk up to a length scale which turns out to coincide with the characteristic wave length of the corrugation. Within the boundary layer where the nematic degree of orientation decre...

The Surface Realisation (SR) Task was a new task at Generation Challenges 2011, and had two tracks: (1) Shallow: mapping from shallow input representations to realisations; and (2) Deep: mapping from deep input representations to realisations. Five teams submitted six systems in total, and we additionally evaluated human toplines. Systems were evaluated automatically using a range of intrinsic ...