A sheet mulch assembly includes a sheet mulch; an irrigation conduit attached to and carried by the sheet mulch; and at least one carrier substrate coupled with the conduit. For example, embodiments of the invention include a method of providing a unidirectional flow valve to a vein that include folding a first portion of a vein over an adjacent second portion of a vein and engaging at least two opposing areas of the second portion of the vein to adjacent areas of the first portion of the vein. In addition, there are provided photolithographic processes comprising directing exposure onto a resist through a mask formed using such methods. In one implementation, the display of the categories and information on the user interface is handled by the main thread and the retrieval of the data associated with the chosen category is performed by a worker thread executing asynchronously with respect to the main thread. The first portion has less electrical resistance than the second portion and a different stoichiometric composition than the second portion. Intensities of the infrared light absorbed in the first material and the dopants are computed according to light wave numbers by utilizing a difference between intensities of the infrared light before and after transmitting the substrate and layer and by utilizing a difference between intensities of the infrared light absorbed in the substrate and layer and absorbed in only the substrate.