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.
The estivation (Summer sleep ) : an other state of dormancy in which like other species snails spend periods of heat or drought in warmer latitudes. 1 - estivation: The snail lives short periods of great activity, which are essential for building up its reserves. These allow him a slowed down long term life.