Electrical resistivity and conductivity results in the important concept of "quasineutrality", which says the density of negative charges is approximately equal to the density of positive charges over large volumes of the plasma ("n" = <Z>"n"), but on the scale of the Debye length there can be charge imbalance. In the special case that "double layers" are formed, the charge separation can extend some tens of Debye lengths. The magnitude of the potentials and electric fields must be determined by means other than simply finding the net charge density. A common example is to assume that the electrons satisfy the Boltzmann relation: Differentiating this
Negative and positive rights or "positive") requires both kinds of duties at once. In other words, Shue says that honouring a right will require avoidance (a "negative" duty) but also protective or reparative actions ("positive" duties). The negative positive distinction may be a matter of emphasis; it is therefore unhelpful to describe "any right" as though it requires only one of the two types of duties. To Shue, rights can always be understood as confronting "standard threats" against humanity. Dealing with standard threats requires all kinds of duties, which may be divided across time (e.g. "if avoiding the harmful behaviour fails, begin to repair