An MR effect element includes a free magnetic layer having a small coercive force and therefore reduces the hysteresis of the R-H loop. Administering to a patient a reduced volume of a PEG in water solution followed by an oral stimulant laxative, such as bisacodyl, after a biologically determined interval, cleanses the colon in preparation for the virtual colonoscopy, without the profuse uncontrollable diarrhea that typically follows either ingestion of the large volume isotonic lavages, or smaller volume hypertonic lavages. The system includes D disks, where D2 and is an integer.