The late stages of evolution of helium star-neutron star binaries and the formation of double neutron star systems

A grommet at one side comprises a tubular part which widens out either in a regular trumpet-shaped curve ("monotonic") or via one or more "steps" or "bends" with the result that the risk of blockage is considerably reduced and the grommet is less quickly expelled from the eardrum. At the other side, the grommet is provided with a flange via which the grommet remains hooked behind the eardrum. This flange is so large - either round and the same size as the widely "fanning" top side of the trumpet-shaped top part of the grommet, or provided with one or more symmetrical or asymmetrical projections - that the grommet is held fast by the eardrum for a relatively long time. A recurrence of the fluid accumulation in the tympanic cavity or of an ear infection is consequently less likely to occur.