WASHINGTON -- A bipartisan duo of Senate heavyweights is set to unveil an unusual bill that would give lawmakers an incentive to fund biomedical research and, potentially, add billions to that mission. Sens. Elizabeth Warren (D-Mass.) and Orrin Hatch (R-Utah) have been quietly working for the past year on the Invest for a Healthy Future Act, a bill that may end up increasing money for government agencies that fund research by more than $21.5 billion over the next dozen years.