Generate a topic word for the given sentence. A topic word is usually the name of a person, place, animal, concept or object the sentence is focusing on.

[EX Q]: henan is a province of the people's republic of china.
[EX A]: henan

[EX Q]: norio yoshimizu (吉水 法生, yoshimizu norio, born august 21, 1946) is a former japanese football player.
[EX A]: norio yoshimizu

[EX Q]: spintronics is a kind of electronics that uses the tiny magnetic fields that come from electrons as well as their electric charge.
[EX A]:
spintronics