HMM: 4 states: 
    flat line long (nucleosome)
        emiss: dnorm(0, sigam0)
        duration.initial: dgamma(shape=2.91, scale=583.1), 500 ~ 10000
        
    flat line short (nucleosome free)
        emiss: dnorm(0, sigam1)
        duration.initial: dunif(100, 500)
        
    line of negative slope (followed by flat line short)
        emiss: dnorm(0, sigam2)
        duration.initial: dnorm(500, 300), 100 ~ 1000

    line of positive slope (followed by flat line long)
        emiss: dnorm(0, sigam3)
        duration.initial: dnorm(500, 300), 100 ~ 1000
