这是省略there is的省略句,即谓语省略了。(there is )是谓语A predominantly non-white neighborhood’s chance of gentrification是主语 more than doubles是定语jumping from 18 percent to 40 percent when magnet and charter schools are available.是现在分词短语作非限制性定语。其中when从句是分词短语中的状语
一个主要的非白人居民的机会化一倍以上,从18%到40%的跳跃