Promethium is necessary for guided weapons and Dysprosium is employed in sonar systems.

CENTERFORSECURITYPOLICY: Center For Security Policy

For instance, the idea that the Navy's sonar systems are harming whales is about as well based in fact as the 1960s fear that fluoride in our water was poisonous.

FORBES: Fact and Comment

President Bush's administration has come under fire in recent months from environmentalists angered by its reluctance to cut carbon emissions, by its moves to weaken endangered species legislation and by its support for naval use of sonar systems that can kill whales.

BBC: US vows 'huge' marine protection

Using sonar, infra-red or vision systems, suppliers are developing ways to detect the size of the passenger in the front seat and to measure how far back they are sitting.

ECONOMIST: A safety bet