Intensive variables reference vectors

Thus far the discussion has been largely confined to a specific set of reference intensities and extensities. However, equations such as (11.10) make clear the possibility of treating more general types of thermodynamic variations. Transformations among thermodynamic variables will correspond to ordinary Euclidean vector transformations, which can therefore be treated simply and systematically in Ms-... 

First, we note that the standard photodetection is a local measurement of the field variables (intensities). At the same time, the Aharonov-Bohm effect represents a topological measurement referred to the properties of vector potential along some loop. In the usual form, the Aharonov-Bohm effect deals with static or slowly time-varying magnetic fields [101]. The effect consists in the appearance of a persistent current in a metallic loop over which the magnetic flux passes. This current is a periodic function of magnetic flux with the period of flux quantum hc/e. Besides that, certain resistance oscillations in the loop incorporated into an external circuit with the same period can occur. 

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