Results 1 - 10 of 40575
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[en] We analyze the current-voltage characteristic of a quantum conduction channel coupled to an electromagnetic environment with arbitrary frequency-dependent impedance. In the weak blockade regime the correction to the Ohmic behavior is directly related to the channel current fluctuations, vanishing at perfect transmission in the same way as shot noise. This relation can be generalized to describe the environmental Coulomb blockade in a generic mesoscopic conductor coupled to an external impedance, as the response of the latter to the current fluctuations in the former
[en] High and low temperature relaxation of crystal steps are described in a unified picture, using a continuum model based on a modified expression of the step-free energy. Results are in agreement with experiments and Monte Carlo simulations of step fluctuations and monolayer cluster diffusion and relaxation. In an extended model where mass exchange with neighboring terraces is allowed, step transparency and a low temperature regime for unstable step meandering are found
[en] Through a very simple treatment we have constructed a lower bound for the statistical fluctuations of total survival probability of particles moving diffusively in a medium with random traps. We show that the asymptotic behaviour of the total survival probability is a non self-averaging quantity in that the fluctuations dominate the mean value. (author). 29 refs
[en] In this paper, we study the two-dimensional magnetic topological insulators from the correlated Chern insulator and the correlated Z2 topological insulator at finite temperature. For the 2D correlated Chern insulator, we find that the thermal-fluctuation-induced magnetic topological insulator (MTI) appears in the intermediate interaction region of the correlated Chern insulator. On the contrary, for the correlated Z2 topological insulator, thermal-fluctuation-induced MTI does not exist. Finally, we offer an explanation on the difference between the two cases. (paper)
[en] We develop a theory of fluctuating hydrodynamics based on extended thermodynamics through studying the 13-variable theory for a monatomic rarefied gas as a representative case. After analyzing the relationship between the present theory and the Landau-Lifshitz theory, we discuss the hierarchy structure of the hydrodynamic fluctuations. -- Highlights: → We develop a theory of fluctuating hydrodynamics based on extended thermodynamics. → We make clear the relationship between the present theory and the Landau-Lifshitz theory. → We find the general hierarchy structure of the hydrodynamic fluctuations basing on extended thermodynamics.
[en] The density fluctuations associated with the formation of large scale cosmic pancake-like and filamentary structures can be evaluated (1) using the Zeldovich approximation (2) for the evolution of non-linear inhomogeneities in the expanding universe. At the scale introduced by these non-linear density fluctuations due to pancakes, the standard scale-invariant correlation function is modified
[en] The dynamics of dispersal-structured populations, consisting of competing individuals that are characterized by different diffusion coefficients but are otherwise identical, is investigated. Competition is taken into account through demographic processes. The problem addressed models natural selection. It is observed that the mean value and the relative width of the initial distribution of the diffusion coefficients characterizing the individuals together with the temporal fluctuations determine the final distribution of the diffusivities (diffusion coefficients leading to the competition success) as well as the final diversity of the system at finite time (the number of different diffusion coefficients present in the system). Large initial mean diffusivity of the system leads to a rather fast disappearance of the diversity. Instead, small initial mean diffusivity of the system leads to a diversity equal to the number of niches forming in the system due to the competitive interactions. The cluster formation is also associated to the competition success of the slower diffusing individuals. The diversity is diminished by the increase of the temporal fluctuations that give the competition advantage to the faster diffusing individuals. Somewhat counterintuitively, under certain conditions the competition success is given by intermediate values of the diffusion coefficients.
[en] It is commonly accepted that contour length fluctuations increase the viscosity exponent for chains that diffuse by reptation. We found that length fluctuations in the necklace model can play an unexpected role as they can also decrease this exponent. A detailed analysis of the interplay between the discrete character of the model and how the fluctuations take place is presented in this work. Basically, we found that when fluctuations are symmetric their influence is the expected one; when fluctuations are not symmetric new effects can appear