Vittarioideae worthy of subgeneric rank, while "Rheopteris" had not yet been discovered. "Haplopteris" he explicitly synonymized with "Vittaria" in 1914. Carl Christensen used the name "Vittarioideae" in Verdoorn's "Manual of Pteridology" in 1938, but did not include a description, leaving it nomenclaturally invalid. Ren-Chang Ching raised Vittariaceae to the rank of a family in 1940. The first well-sampled molecular phylogenetic study of the vittarioids was based on the chloroplast gene rbcL. In this study, it was found that the type species of "Monogramma" is embedded in "Haplopteris"; the segregation of "Vaginularia" from "Monogramma" was also supported, as members of "Vaginularia" formed
Economics of nuclear power plants due to significantly lower labour rates. A 2008 study by former utility staffperson Craig A. Severance based on historical outcomes in the United States said costs for nuclear power can be expected to run $0.25–0.30 per kWh. A 2008 study concluded that if carbon capture and storage were required then nuclear power would be the cheapest source of electricity even at $4,038/kW in overnight capital cost. In 2009, MIT updated its 2003 study, concluding that inflation and rising construction costs had increased the overnight cost of nuclear power plants to about $4,000/kW, and thus increased the power cost to $0.084/kWh.