Sentence:  The conjecture made in Tsinober and Levich (1983) was that coherent structures should possess a significant coherent <WSD>helicity</WSD>. 
Meaning of the word marked with <WSD> tags:  Any of certain measures of the extent to which vortex lines (in fluid flow) or field lines (in a magnetic or electromagnetic field) kink and twist and/or link and coil around one another.