This article considers the problem of testing for a nonstochastic seasonal unit root in a seasonally observed time series process against the alternative of a randomized seasonal root with mean unity; ...

Although the question of whether Purchasing Power Parity (PPP) holds in the long run has been extensively studied, the answer is still controversial. Some of the strongest evidence is provided by ...

A computer made from strands of DNA in a test tube can calculate the square root of numbers up to 900. Chunlei Guo at the University of Rochester in New York state and colleagues developed a computer ...