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: Diurnal cycles Diurnal cycles are the daily cycles of light and darkness. 
Sentence2: Plants detect and respond to diurnal cycles.
Diurnal

Sentence1: a seismometer is used to measure the strength or magnitude of an earthquake. 
Sentence2: Seismometer Calibration : Instructions on how to calibrate a homemade seismometer.
seismometer

Sentence1: exercise has a positive impact on a human 's health. 
Sentence2: Resistance exercises are weight-lifting exercises.

exercise