In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 

[EX Q]: Electrical signals in the brain travel through nerves to muscles. Two types of proteins exist in filaments in the muscles. The filaments move when the brain instructs them to. The motion of the filaments cause the muscle to shorten and contract. Opposing pairs of muscles exist in order to provide the necessary range of motion. 
[EX A]: electrical signals ,proteins ,filaments 

[EX Q]: Warm, moist air moves from south to north. Cool, dry air moves from north to south. The air masses meet. The conditions that form are not stable because the air masses are so different. Winds are directed in a certain way because of how the masses interact. An updraft results. Winds start to form circular patterns in the updraft. A tornado can result. 
[EX A]: warm, moist air ,cool, dry air ,air masses ; masses ,wind ,updraft ,circular patterns ,tornado 

[EX Q]: A nuclear reactor generates heat by nuclear fission. The heat created raises steam. The steam runs through turbines. The turbines generate electricity. The electricity leaves the station. 
[EX A]:
heat ,steam ,electricity