The seismologist is studying earthquake prediction and disaster prevention.

He is a world-renowned zoologist.

My father is an ichthyologist and has a deep knowledge about marine life.

He always likes to be pedantic, explaining things down to the smallest detail.

He is a renowned economist who has written many important papers.

He is world-famous as an entomologist.

He is a renowned political scientist who has written many important papers.

He is known as a government scholar.

He is a world-famous physicist.

He is a world-famous geographer.