Phrynopus AmphibiaWeb keeps "Noblella" in Strabomantidae/Strabomantinae, a family/subfamily no longer recognized by the Amphibian Species of the World. "Phrynopus" are small to medium-sized frogs, from snout–vent length in "Phrynopus auriculatus" to in "Phrynopus kauneorum". Head is narrower than the body. Differentiated tympanic membrane and tympanic annulus are usually absent, except in "Phrynopus auriculatus" and "Phrynopus peruanus", two basal species. Dorsum is smooth to pustulate. Venter is smooth or areolate. There are 26 species in this genus: Phrynopus Phrynopus is a genus of frogs of the Craugastoridae family. Their common name is Andes frogs. They are endemic to Peru and inhabit the
Dirac membrane Dirac membrane A model of a charged membrane introduced by Paul Dirac in 1962. Dirac's original motivation was to explain the mass of the muon as an excitation of the ground state corresponding to an electron. Anticipating the birth of string theory by almost a decade, he was the first to introduce what is now called a type of Nambu–Goto action for membranes. In the Dirac membrane model the repulsive electromagnetic forces on the membrane are balanced by the contracting ones coming from the positive tension. In the case of the spherical membrane, classical equations of motion imply that the