A birefringent film which comprises a compound having a proton-accepting group and a compound having a proton-donating group; and a birefringent film which comprises a compound having a proton-accepting group and a proton-donating group. The method includes generating an increment of the disturbance signal, and modifying an incremental signal input to the dynamic system based on the increment of the disturbance signal, thereby reducing the effect of the disturbance signal. Clustering may include clustering based on a histogram that may be generated for each file pair of the plurality of files. The power and ground contacts are arranged in an alternating pattern in the housing. In another embodiment, a preferred WTRU is configured to receive paging messages, based on a PICH and a HS-PDSCH. Image artifacts due, for example, to high-contrast objects such as, for instance, cardiac pacemakers or metallic implants, in the x-ray image will be avoided through this measure.