Generate an overlapping word between the given two sentences. When you find the overlapping words, they don't have to match exactly, e.g., "survival" and "survive" are valid overlapping words. Little words like "the" or "of" don't count! You must generate significant words which are not the stop words.

Sentence1: Oxygen fatigue is a shortage of oxygen reaching the brain.
Sentence2: Plants can reduce fatigue during the daytime.
fatigue

Sentence1: a switch is used to start the flow of current in an electrical circuit.
Sentence2: The flow of electrical current powers a light bulb.
current

Sentence1: Transcription takes place in the nucleus.
Sentence2: DNA transcription is the process where a copy of the DNA is made.
Transcription