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where " ρ " − " ρ " is the difference in density of particles separated by a height difference of " h " , " k " is the Boltzmann constant ( the ratio of the universal gas constant , " R " , to the Avogadro constant , " N " ) , and " T " is the absolute temperature .
 person: Boltzmann; person: Avogadro
Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: location, person, organization 
Text: {0} 
Answer:
 person: Boltzmann; person: Avogadro