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Other mechanisms have also been proposed , in particular , Alfvén waves , wave modes involving the magnetic field first noted by Hannes Alfvén ( 1942 ) , which have been observed in the laboratory and in space .
 person: Alfvén; person: Hannes Alfvén
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
 Entities: Alfvén, Hannes Alfvén 
Answer:
 person: Alfvén; person: Hannes Alfvén