Disclosed is a bedstead board having at least one recess near a first or a second side. An exemplary technique includes providing a semiconductor substrate that includes a shallow trench isolation structure disposed therein. Gravity is then used to concentrate the complex and the concentrate is assayed to detect prions. The valve is suitable for causing the inlet to communicate with the outlet when the pressure in said main pipe reaches a given pressure threshold. Then the install system is executed from the temporary directory.