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: Antibiotics and vaccines are being stockpiled as Britain gears up to meet the bioterrorism threat. 
Sentence2: Antibiotics and vaccines are being stockpiled against another potential threat in the environment.
Antibiotics

Sentence1: Scientists still know relatively little about Archaea. 
Sentence2: scientists still know relatively little about non-bacterial prokaryotes.
Scientists

Sentence1: the Earth being tilted on its axis causes ones side of the Earth to receive less energy from the Sun than the other side. 
Sentence2: one side of the Earth receives less solar power from the Sun than the other side.

Earth