The Massachusetts medical community was there in force after Hurricane Katrina pummeled the Gulf Coast in 2005. About 40 local surgeons and nurses flew to Port-au-Prince, Haiti, after last year's devastating earthquake there. They even traveled to Bam, Iran, after an earthquake toppled buildings and killed thousands in 2003. But their phones have been largely silent since last week's twin disasters in Japan. Japan, a highly industrialized nation with a healthcare system that remains mostly intact, has little need for outside medical expertise, but it has requested more technical assistance after Friday's earthquake and tsunami. It has deployed search-and-rescue crews from overseas, consulted international scientists to try to stave off the threat of a meltdown at a nuclear plant, and received help from engineers with geo-mapping skills.