According to studies by Erle Ellis, an ecologist at the University of Maryland, Baltimore County, the vast majority of ecosystems on the planet now reflect the presence of people.

Anil Gupta, of the University of Maryland at College Park, points out that these markets are among the toughest in the world.

At the end of the week, both parties nominated two candidates for the Boys nation program, to be held toward the end of July at the University of Maryland in College Park, near the nation's capital.