anchor.diff:    public :: dust_scatter_peeloff
     public :: dust_sample_emit_probability
     public :: dust_sample_emit_frequency
  -  public :: dust_sample_emit_frequency_eta_nu
     public :: dust_jnu_var_pos_frac
   
     type dust
  
positive.code: 
      ! Allocate emissivity PDF
      allocate(d%j_nu(d%n_jnu))
      allocate(d%e_nu(d%n_jnu))
  
      do i=1,d%n_jnu
         call set_pdf(d%j_nu(i),emiss_nu,emiss_jnu(i,:),log=.true.)
  
negative.code:      real(dp),allocatable :: j_nu_var(:)          ! independent emissivity variable
       real(dp),allocatable :: log10_j_nu_var(:)    ! independent emissivity variable [Log10]
       type(pdf_dp),allocatable :: j_nu(:)          ! emissivity
  
       ! integer :: beta ! power of the photon energy sampling
       ! real(dp),allocatable  :: a(:) ! Energy of the emitted photon = a*nu^beta * incoming energy
  