text: We now return to the discussion of the validity of Eq. (7). 
  As mentioned, the series coupling of individual scatterers 
  should be valid when lφ < d. However, even for lφ > d 
  and assuming that the Anderson localization length, lloc in 
  the system exceeds lφ, Eq. (7) remains valid if one replaces 
  the actual resistance R by the sample averaged resistance (cid:104)R(cid:105) 
  [29]. At room temperature under ambient conditions, interac- 
  tions with external degrees of freedom such as internal CNT 
  phonons and vibrational modes of the adsorbed molecules 
  would rapidly randomize the phase of the electrons. There- 
  fore Eq. (7) should certainly be valid in the limit of low dop- 
  ing concentrations. On the other hand, the total number of 
  dopants, N , should be large enough for the statistical treat- 
  ment of the coverage to hold. Finally, we stress that Eq. (7) 
  represents a conservative estimate of the change in resistance. 
  In fact, in the regime where lφ > lloc, i.e. in the Anderson 
  localization regime, the resistance would be highly sensitive 
  to changes in the fractional coverage of active sites. Calcula- 
  tion of the actual resistance of the CNT in this regime would, 
  however, involve a full transport calculation in the presence of 