University of Louisville officials are close to a decision on a developer for the school’s new life sciences research centerThe Nucleus life sciences corridor is planned for the old Haymarket block downtown, at the corner of Market and Floyd streets. Last year, U of L split with the project's previous developer over a difference in business plans. In December, the school sent out requests for qualifications and has received 14 proposals.Nucleus President Vicki Yates Brown says a new developer will likely be chosen by mid May, and construction will continue for several years."No developer's going to say 'Let's develop the whole block at the same time,' so they're going to suggest a phasing on the block I think," she says.Brown says the first building on the block will be a parking garage. She hopes construction on that will start this summer.