This disclosure generally relates to a processor configured to access an element in a data structure. In one embodiment, the method comprises removing L-cells from a donor, obtaining stem cells from a patient, and culturing the L-cells in the presence of the stem cells under conditions such that the stem cells differentiate into stem cell-derived L-cells. The test and reference images are converted into sets of geometric constructs, or \u201cprimitives,\u201d that are used to approximate features of the images. Preferably, the solid graphene foam has a density from 0. A number of flow disrupting structures, such as microfins and trip strips, can be located along the flow passage. 25, preferably 0<\u03b4<0.