MRI of a knee. MRIs employ powerful magnets which produce a strong magnetic field that forces protons in the body to align with that field. When a radiofrequency current is then pulsed through the patient, the protons are stimulated, and spin out of equilibrium, straining against the pull of the magnetic field.
Noun. 1. aestivation - (zoology) cessation or slowing of activity during the summer; especially slowing of metabolism in some animals during a hot or dry period. estivation. zoological science, zoology-the branch of biology that studies animals.
Noun. 1. inactivation-the process of rendering inactive; the gene inactivation system; thermal inactivation of serum samples. natural action, natural process, action, activity-a process existing in or produced by nature (rather than by the intent of human beings); the action of natural forces; volcanic activity.. inactivation-the process of rendering inactive; the gene inactivation system; thermal inactivation of serum samples. natural action, natural process, action, activity-a process existing in or produced by nature (rather than by the intent of human beings); the action of natural forces; volcanic activity.