The present invention provides an electro-optic unit. Also disclosed is the use of such transgenic animals and transfected cell lines to screen potential drug candidates for treating or preventing Alzheimer’s disease, neuroectodermal tumors, malignant astrocytomas, and glioblastomas. The guidance device includes two side walls and a slot defined therebetween so that the film passes through the slot before being mounted to the shaft. The UE may operate at least one of a CDRX on duration timer or an inactivity timer of the first RAT while the single radio of the UE is being used for the second RAT.