text: 3 
  
  conductances, i.e. G = (G↑ + G↓)/2. 
  
  Next, we estimate the resistance of a CNT containing sev- 
  eral impurities (a speciﬁc metal dopant with different molecu- 
  lar adsorbates). Under the assumption that the electron phase- 
  coherence length, lφ, is smaller than the average distance be- 
  tween the dopants, d, we may neglect quantum interference 
  and obtain the total resistance by adding the scattering resis- 
  tances due to each impurity separately. The scattering resis- 
  tance due to a single impurity is given by 
  
  Rs(X) = 1/G(X) − 1/(2G0),  (6) 