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.
For emergency stop mechanisms, see kill switch. Estoppel is a collective name given to a group of legal doctrines in common law legal systems whereby a person is prevented from making assertions that are contradictory to his or her prior position on certain matters before the court - the person is said to be estopped.