<prompt> Translate the following text to EnglishMtaalamu wa uchumi George Gilder anasema kuwa miji ya Marekani ni vituo vya kuondoa thamani, vimelea vinavyomnyunyiza maisha ya kijamii na kiuchumi kutoka kwa nchi nzima.  <response>: Economist George Gilder now speaks of Americas cities as centers of value subtraction--parasites that suck social and economic vitality from the rest of the country. 