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).
Research the causes of these diseases that are similar to, or related to, Batten Disease: 1  Autosomal recessive disorder. 2  Neurodegenerative disorder. 3  Neuronal ceroid lipofuscinosis. 4  Echolalia. Seizures.  Vision 1  problems. more related diseases...Â».