However sailing ships are particularly vulnerable because the ship naturally heels over in reaction to the force of the wind on the sails.

Passenger rail travel was very vulnerable because government regulations required certain levels of service even if unprofitable.

"That's why they're vulnerable, because the first couple of years they're counting nickels to pay their bills," Mr. Castellano said.

It is classified as vulnerable because it breeds on just three small islands.

Many foreign workers remain vulnerable to trafficking because legal protections, oversight by authorities and enforcement efforts are inadequate.

The latter, vulnerable because they do not understand the problems and cannot discover anyone who does.

Women under 24 years of age are especially vulnerable because the risk of developing complications during pregnancy and childbirth.

Such ice conditions may have been especially likely in cold years when the Norse were already vulnerable because of cold summers and hence low hay production.

But all three groups appeared vulnerable to challenge, because each submitted only a few thousand signatures over the 15,000 required by law.

The eastern side of the citadel was more vulnerable from the point of view of natural obstacles because its u-shape.