Investigation of in vivo models of disease requires imaging studies involving single subjects in single imaging sessions, serial imaging of individuals or groups of subjects, and integration of data across diverse and heterogeneous experimental methodologies. Compositions comprising the terminal-modified difunctional sulfur-containing polymers useful as sealants are also disclosed. In another embodiment the towel stowing means, when initiated by a user, automatically retracts the towel into the second position. An end of the first beam is fixed on the first seat, the other end of the first beam and two ends of the second beam are respectively fixed on the second seats by an adjustable device.