For example, those single taxpayers with $5,000 of Social Security benefits in the example above would see their marginal tax rate on nonâSocial Security income boosted by 50 percent if their modified AGI was between $25,000 and $30,000 and by 85 percent if their modified AGI was between $34,000 and $36,000.
Three types of vault were commonly used: the barrel-vault, the groined or four-part vault, and the dome. The barrel-vault was generally semi-cylindrical in section, and was used to cover corridors and oblong halls, like the temple-cellas, or was bent around a curve, as in amphitheatre passages.
Arches and vaults. Known at least since the 3rd dynasty, true arches were rarely used in early Ancient Egypt. Only when the building material was mud bricks and building corbelled vaults was impractical, were true arches erected. In Djoser's great mastaba a barrel-vault has been found. It was built with bricks wedged together and bonded from above with gravel and mortar.