Sentence:  The <WSD>efforts</WSD> and accomplishments fall into three main categories : absolute thermometry based upon the velocity of sound in helium gas , secondary thermometry involving principally studies of the behavior of germanium resistors , and helium 4 vapor-pressure measurements ( see p. 144 ) . 
Meaning of the word marked with <WSD> tags:  earnest and conscientious activity intended to do or accomplish something