21.   Self-confidence helps build a protective barrier.

22.   Slowly but surely, the traditional protective barriers in Europe do seem to be coming down.

23.   Skin also forms a protective barrier.

24.   Some corporations and other institutions have firewalls, or software that acts as a protective barrier between machines inside the institution and those outside.

25.   Some of the bunkers are currently being used as protective barriers around the NATO encampments.

26.   That acted as a protective barrier against infection when SIV, the simian AIDS virus, was squirted into the vagina to test the effectiveness of the therapy.

27.   The drug mops up some of the dangerous chemicals, forms a protective barrier around at-risk brain cells, and limits intracranial inflammation.

28.   The same overbearing seamless facades that line the street became a protective barrier.

29.   The United States and the European Union are already knocking down protective barriers in their telephone, cable television and data markets.