Some explanation: There's a legal limit to federal debt, which must be raised periodically if the government keeps running deficits; the limit will be reached again this spring.
Allegations that granite countertops may emit dangerous levels of radon and radiation have been raised periodically over the past decade, mostly by makers and distributors of competing countertop materials.
Initially landlords like Grosvenor Estates, the biggest in Mayfair and owned by the Duke of Westminster, were reluctant to end commercial usage as rents could be raised periodically while residential property, in contrast, could produce just a single sale.
But legislators don't have to fret: their packages are based on the salaries of judges, which are currently set at $125,000 (a bigger number that can be raised periodically without the political risk of touching legislative salaries).
As enrollments have increased over the years, questions have been raised periodically about whether to build new schools or add on to existing ones — thereby maintaining the Princeton plan.
The idea of forcing companies to change auditors, perhaps every seven or 10 years, has been raised periodically in response to accounting scandals since at least 1977, when Senator Lee Metcalf suggested such a step in the wake of the scandal at Equity Funding, an insurance and mutual fund company that falsified its sales figures.
As long as a request is unfulfilled, the hormone level is raised periodically, thus increasing the concentration of hormones at the sender end, encouraging diffusion of hormones towards the receiver, until the request is fulfilled.
-- has been raised periodically for decades, and it is in practice in dozens of schools around the country.
Doubts have also been raised periodically about whether the entire Life is a forgery, written by a slightly later writer, but it is now almost universally accepted as genuine.
Rotterdam officials recognize that the city's primary dikes will need to be raised periodically to keep up with rising seas and that the city's storm surge barrier built after a major flood in 1953 also will only protect the city so long as sea level rise is less than half a meter.
He rarely raises his voice, yet periodically seems on the cusp of yelling" .
