The Varying Permeability Model, Variable Permeability Model or VPM is an algorithm that is used to calculate the decompression stops needed for ambient pressure dive profiles using specified breathing gases. It was developed by D.E. Yount and others for use in professional diving and recreational diving. It was developed to model laboratory observations of bubble formation and growth in both inanimate and in vivo systems exposed to pressure.[1] In 1986, this model was applied by researchers at the University of Hawaii to calculate diving decompression tables.[citation needed]