Symmetries in Fluctuations Far from Equilibrium

Fluctuations arise universally in Nature as a reflection of the discrete microscopic world at the macroscopic level. Despite their apparent noisy origin, fluctuations encode fundamental aspects of the physics of the system at hand, crucial to understand irreversibility and nonequilibrium behavior. In order to sustain a given fluctuation, a system traverses a precise optimal path in phase space. Here we show that by demanding invariance of optimal paths under symmetry transformations, new and general fluctuation relations valid arbitrarily far from equilibrium are unveiled. This opens an unexplored route toward a deeper understanding of nonequilibrium physics by bringing symmetry principles to the realm of fluctuations. We illustrate this concept studying symmetries of the current distribution out of equilibrium. In particular we derive an isometric fluctuation relation which links in a strikingly simple manner the probabilities of any pair of isometric current fluctuations. This relation, which results from the time-reversibility of the dynamics, includes as a particular instance the Gallavotti-Cohen fluctuation theorem in this context but adds a completely new perspective on the high level of symmetry imposed by time-reversibility on the statistics of nonequilibrium fluctuations. The new symmetry implies remarkable hierarchies of equations for the current cumulants and the nonlinear response coefficients, going far beyond Onsager's reciprocity relations and Green-Kubo formulae. We confirm the validity of the new symmetry relation in extensive numerical simulations, and suggest that the idea of symmetry in fluctuations as invariance of optimal paths has far-reaching consequences in diverse fields.Comment: 8 pages, 4 figure

Reentrant Behavior of the Spinodal Curve in a Nonequilibrium Ferromagnet

The metastable behavior of a kinetic Ising--like ferromagnetic model system in which a generic type of microscopic disorder induces nonequilibrium steady states is studied by computer simulation and a mean--field approach. We pay attention, in particular, to the spinodal curve or intrinsic coercive field that separates the metastable region from the unstable one. We find that, under strong nonequilibrium conditions, this exhibits reentrant behavior as a function of temperature. That is, metastability does not happen in this regime for both low and high temperatures, but instead emerges for intermediate temperature, as a consequence of the non-linear interplay between thermal and nonequilibrium fluctuations. We argue that this behavior, which is in contrast with equilibrium phenomenology and could occur in actual impure specimens, might be related to the presence of an effective multiplicative noise in the system.Comment: 7 pages, 4 figures; Final version to appear in Phys. Rev. E; Section V has been revise

An Exploratory Study to Develop a Geotourism Typology Model Based on the Experience and the Importance of Geotourism in the Decision to Visit a Destination

This study develops a typology model for geotourism to address the existing gap in the literature regarding who is participating in geotourism. As geotourism is a new concept, the literature is not only lacking in this area, but there is also a conflict of definitions available from scholars and organisations. This study defines geotourism in accordance to the definition of Newsome and Dowling (2010). It also aims to reduce the gap in literature by providing a starting point to the development of future geotourism typology models through the adaptation of McKercher\u27s Cultural Tourism Typology Model (2002). Participants eligible for this study were tourists participating in the Crystal Cave in Yanchep National Park, Perth, Western Australia. This site was chosen as the Crystal Cave\u27s management is practicing geotourism. Therefore, it was assumed tourists were participating in geotourism as Yanchep National Park, including the Crystal Cave, comply with the definition. Geotourism focuses on sustainability, conservation, benefitting the community, appreciation of cultural and geoheritage value through education and interpretation and tourist satisfaction (Dowling, 2008). Management places importance on the sustainability and conservation of the cave. Tourists have the opportunity to learn as they are provided with educational opportunities in the guided tour through the cultural and geoheritage interpretation. It also benefits the community as it creates job opportunities. Furthermore, results of the study demonstrate that locals visit the cave benefitting them through their positive participation and experiences. The data was collected through on-site self completed questionnaires. Analysis included a criteria sheet and guidelines established in accordance to the description of each of McKercher\u27s typologies as well as Statistical Package for the Social Sciences 17 (SPSS). After the analysis of the results, it became evident that the Cultural Tourism Typology Model (2002) could not be applied to geotourism as some typologies needed to be adapted and new typologies were discovered. As a result, a new model was re-developed based on McKercher\u27s Model. Purposeful tourists and incidental tourists remained with the same characteristics. The serendipitous tourist typology was changed slightly to include some gee-motivation. Furthermore, two new typologies were created as a result of the data analysis. The new typologies are the \u27intentional geotourist\u27 who is characterised by high geo-influence and positive encounter, and the \u27accidental geotourist\u27 who has no geo-influence and a positive encounter

Reply to comment on "Simple one-dimensional model of heat conduction which obeys Fourier's law"

In this reply we answer the comment by A. Dhar (cond-mat/0203077) on our Letter "Simple one dimensional model of heat conduction which obeys Fourier's law" (Phys. Rev. Lett. 86, 5486 (2001), cond-mat/0104453)Comment: 1 pag., 1 fi