RESUMO
A novel type of dual concentric core photonic crystal fiber (PCF) is proposed and theoretically analyzed, aiming at the design of tunable dispersive fiber elements for polarization-mode-dispersion (PMD) compensation. The adjustment of the fiber's geometrical birefringence through the proper selection of structural parameters leads to very high values of differential group-delay (DGD). Moreover, the value of DGD can be dynamically tuned by infiltrating the outer core capillaries of the PCF with an optical liquid, which allows for the thermal control of its refractive index. Such fibers are envisaged as tunable dispersive fiber elements for PMD compensation or emulation modules.
RESUMO
Both the forward and inverse problems of electrocardiography rely on the precise modelling of the anatomic and electrical properties of the thoracic tissues. This, in turn, requires good knowledge of the electrical anisotropy as well as conductivity inhomogeneity of the heart, lungs and the rest of the thorax. Cardiac electrical anisotropy is related to its microstructure (fibre length, density and orientation). We hereby present detailed three-dimensional (3D) meshes of the thorax and heart, using image data from contiguous 2D magnetic resonance (MR) imaging slices as well as a realistic 3D cardiac fibre orientation model that derives its data from high-resolution ex vivo human heart MR images and from histology specimens of heart tissue. Using specific software, we integrated the 3D thorax and heart meshes in one that addresses the related modelling requirements for the solution of the forward and inverse problems of electrocardiography.
