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.
US Open Tennis Championship Tickets. There are no events available in your area. The U.S. Open began in 1881, though it was slightly different than it is today. Back then, it was played on lawn courts in the Newport Casino in Rhode Island and players competed to overthrow the previous year's winner, who automatically made it to final match.