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).
Paget disease of the breast is named after the 19th century British doctor Sir James Paget, who, in 1874, noted a relationship between changes in the nipple and breast cancer. (Several other diseases are named after Sir James Paget, including Paget disease of bone and extramammary Paget disease, which includes Paget disease of the vulva and Paget disease of the penis.