The two photocells are linked to the Tree: the Pre-Stage, and the Stage lights. When the car inches forward and blocks the first photocell, the Pre-Stage light comes on, indicating that the driver is close to the starting line. Most tracks have a rollout, or distance between the Pre-Stage and Stage beams of 6-8.
Batten disease is named after the British pediatrician Frederick Batten, who first described it in 1903. Also known as Spielmeyer-Vogt-SjÃ¶gren-Batten disease, it is the most common form of a group of disorders called neuronal ceroid lipofuscinosis (or NCLs).
Blount's disease. Blount's disease is a growth disorder of the tibia (shin bone) that causes the lower leg to angle inward, resembling a bowleg. It is also known as tibia vara. It is named after Walter Putnam Blount (1900â1992), an American pediatric orthopedic surgeon.