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).
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.