He is traveling around the world as an ecologist.

He is a world-renowned bacteriologist.

He is a renowned criminologist who has contributed to many crime analyses.

The seismologist is studying earthquake prediction and disaster prevention.

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

He is world-famous as an entomologist.

He is known as a government scholar.

He is a famous psychologist, influencing many people.

He is a world-renowned geologist.

He is a world-renowned osteologist.