( ( Low E ) ( ( ( ( ( keeps ( warm air ) ) in ) , ) ( ( ( ( cold air ) out ) and ) ( vice versa ) ) ) . ) )
(ROOT (S (NP (NNP Low) (NNP E)) (VP (VBZ keeps) (NP (JJ warm) (NN air)) (PP (IN in)) (, ,) (ADVP (ADVP (NP (JJ cold) (NN air)) (IN out)) (CC and) (ADVP (RB vice) (RB versa)))) (. .)))
Low E keeps warm air in, cold air out and vice versa.
(ROOT (S (NP (NP (DT The) (JJR lower) (NN density)) (PP (IN of) (NP (JJ warm) (NN air)))) (VP (VBZ causes) (S (NP (PRP it)) (VP (TO to) (VP (VB rise) (PP (IN above) (NP (JJ cold) (NN air))))))) (. .)))