convulsion vs upturn

convulsion

noun
  • An uncontrolled fit, as of laughter; a paroxysm. 

  • An intense, paroxysmal, involuntary muscular contraction. 

  • Violent turmoil. 

upturn

noun
  • an upward turn or trend, especially in business activity or profit 

verb
  • to turn (something) up or over 

How often have the words convulsion and upturn occurred in a corpus of books? (source: Google Ngram Viewer )