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.
Eventually, children with Batten disease become blind, bedridden, and demented. Batten disease is often fatal by the late teens or twenties. Batten disease is named after the British pediatrician F. E. Batten who first described it in 1903. Also known as Spielmeyer-Vogt-Sjogren-Batten disease, it is the most common form of a group of disorders called Neuronal Ceroid Lipofuscinoses (or NCLs).
Angelman syndrome (/ËeÉªndÊÉlmÉn/ ; abbreviated AS) is a neuro-genetic disorder characterized by severe intellectual and developmental disability, sleep disturbance, seizures, jerky movements (especially hand-flapping), frequent laughter or smiling, and usually a happy demeanor.he sister syndrome, Prader-Willi syndrome, is caused by a similar loss of paternally inherited genes and maternal imprinting. AS is named after a British pediatrician, Harry Angelman, who first described the syndrome in 1965.