Radioimmunoassay (RIA) is a very sensitive in vitro assay technique used to measure concentrations of antigens (for example, hormone levels in blood) by use of antibodies. As such, it can be seen as the inverse of a radiobinding assay, which quantifies an antibody by use of corresponding antigens. Although the RIA technique is extremely sensitive and extremely specific, requiring specialized equipment, it remains among the least expensive methods to perform such measurements.
Everything American Express is offering during the US Open this year is designed to enhance what tennis fans love about this tournament, said Deborah Curtis, vice president of entertainment and sports marketing at American Express.
The U.S. Open is the economic engine that helps us promote tennis through the remainder of the year, he said. Tournament ticket revenue of $98.5 million last year represented almost 40 percent of the Open's overall revenue of $253 million.