A telescoping tube for supporting surrounding walls of a shaft during the rescue of a victim trapped at the bottom of the shaft. In response to user operation, at least one determined feature word can be changed. A frame control device may receive first display data, determine a total amount of current passing through each of the scan lines, and provide second display data to the panel based on the determined total amount of current. Information from and commands to each of the individual battery cells can be relayed through a low-power serial bus in order to form \u201cintelligent\u201d and optimally managed battery systems. An external magnetic field can change the magnetization state of the device by orienting the magnetization of the ferromagnetic layers to be parallel or antiparallel, thus changing the resistance of the device to a current of spin polarized electrons. Patterned optical elements such as retarders or liquid crystal elements for use in optical retarders are also described.