sentence1: in nature , the entities themselves tend to be complex and expressed as noun phrases containing multiple modifiers , giving rise to examples like oxygen depletion in the upper 500 m of the ocean or timing and magnitude of surface temperature evolution in the southern hemisphere in deglacial proxy records .
sentence2: variables tend to be complex rather than atomic entities and expressed as noun phrases containing multiple modifiers , e.g . oxygen depletion in the upper 500 m of the ocean or timing and magnitude of surface temperature evolution in the southern hemisphere in deglacial proxy records .