Calvo, IvánSánchez, RaúlCarreras, Benjamín A.Van Milligen, Boudewijn Ph.2010-06-162010-06-162007-12-07Phys. Rev. Lett. 99, 230603 (2007)0031-9007http://hdl.handle.net/10016/89034 pages, no figures.-- PACS nrs.: 05.60.-k, 05.10.Gg, 05.40.Fb.-- ArXiv preprint available at: http://arxiv.org/abs/0712.1798In the study of transport in inhomogeneous systems it is common to construct transport equations invoking the inhomogeneous Fick law. The validity of this approach requires that at least two ingredients be present in the system. First, finite characteristic length and time scales associated with the dominant transport process must exist. Second, the transport mechanism must satisfy a microscopic symmetry: global reversibility. Global reversibility is often satisfied in nature. However, many complex systems exhibit a lack of finite characteristic scales. In this Letter we show how to construct a generalization of the inhomogeneous Fick law that does not require the existence of characteristic scales while still satisfying global reversibility.application/pdfeng© The American Physical Society[PACS] Transport processes[PACS] Stochastic analysis methods (Fokker-Planck, Langevin, etc.)[PACS] Random walks and Levy flightsresearch articleFísicaFusión10.1103/PhysRevLett.99.230603open access