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.
Word Origin and History for estivate Expand. v. to spend the summer, mid-17c., from Latin aestivatus, past participle of aestivare to spend the summer, from aestus heat, aestas summer, literally the hot season, from Proto-Italic *aissat-, from PIE *aidh- to burn (see edifice). Related: Estivated; estivating.