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 after a disaster. This consideration has led ethicists to agree in a general way that positive obligations are usually junior to negative obligations because they are not reliably "prima facie". Some critics of positive rights implicitly suggest that because positive obligations are not reliably "prima facie" they must always be agreed to through contract. Nineteenth-century philosopher Frédéric Bastiat summarized the conflict between these negative and positive rights by saying: According to Jan Narveson, the view of some that there is no distinction between negative and positive rights on the ground that negative rights require police and courts for their enforcement