Search results for "Statistical physics"
showing 10 items of 1402 documents
Short chaotic strings and their behaviour in the scaling region
2008
Coupled map lattices are a paradigm of higher-dimensional dynamical systems exhibiting spatio-temporal chaos. A special case of non-hyperbolic maps are one-dimensional map lattices of coupled Chebyshev maps with periodic boundary conditions, called chaotic strings. In this short note we show that the fine structure of the self energy of this chaotic string in the scaling region (i.e. for very small coupling) is retained if we reduce the length of the string to three lattice points.
Overload breakdown in models for photosynthesis
2015
In many models of the Calvin cycle of photosynthesis it is observed that there are solutions where concentrations of key substances belonging to the cycle tend to zero at late times, a phenomenon known as overload breakdown. In this paper we prove theorems about the existence and non-existence of solutions of this type and obtain information on which concentrations tend to zero when overload breakdown occurs. As a starting point we take a model of Pettersson and Ryde-Pettersson which seems to be prone to overload breakdown and a modification of it due to Poolman which was intended to avoid this effect.
Analytical properties of horizontal visibility graphs in the Feigenbaum scenario
2012
Time series are proficiently converted into graphs via the horizontal visibility (HV) algorithm, which prompts interest in its capability for capturing the nature of different classes of series in a network context. We have recently shown [1] that dynamical systems can be studied from a novel perspective via the use of this method. Specifically, the period-doubling and band-splitting attractor cascades that characterize unimodal maps transform into families of graphs that turn out to be independent of map nonlinearity or other particulars. Here we provide an in depth description of the HV treatment of the Feigenbaum scenario, together with analytical derivations that relate to the degree di…
Feigenbaum graphs: a complex network perspective of chaos
2011
The recently formulated theory of horizontal visibility graphs transforms time series into graphs and allows the possibility of studying dynamical systems through the characterization of their associated networks. This method leads to a natural graph-theoretical description of nonlinear systems with qualities in the spirit of symbolic dynamics. We support our claim via the case study of the period-doubling and band-splitting attractor cascades that characterize unimodal maps. We provide a universal analytical description of this classic scenario in terms of the horizontal visibility graphs associated with the dynamics within the attractors, that we call Feigenbaum graphs, independent of map…
Entropy
2008
Noise-induced transitions in a stochastic Goodwin-type business cycle model
2017
Abstract We motivate and specify a stochastic Goodwin-type business cycle model. Our analysis focusses on a subset of the parameter space where several attractors coexist. Applying a semi-numerical approach based on the stochastic sensitivity function and confidence domains due to Milstein and Ryashko (1995) , we study random transitions between stable attractors in the context of the Goodwin-type economy embedded in an uncertain environment. Relying on a mix of analytical considerations and simulations we demonstrate that under weak noise levels regime switching is a prominent feature in the presence of low saving rates. Moreover, we explain how increased uncertainty can induce an essentia…
Electromagnetic Form Factors in the Time Like Domain
2008
The electromagnetic form factors in the time like domain can be accessed by the reaction p ¯ p → e + e − or its time inversed process. Despite a long standing experimental effort to determine these form factors, the precision in the knowledge of the ratio | G E | / | G M | ist still very poor in the time like domain. All world data suffer from limited statistics and therefore have used the hypothesis of | G E | = | G M | in order to extract a value for | G M | . While there is no theory argument for this hypothesis, recent JLAB data from polarisation transfer in elastic electron scattering show, that this hypothesis does not hold. Only a few data points allow the determination of | G E | / …
On the annual modulation signal in dark matter direct detection
2012
We derive constraints on the annual modulation signal in Dark Matter (DM) direct detection experiments in terms of the unmodulated event rate. A general bound independent of the details of DM distribution follows from the assumption that the motion of the earth around the sun is the only source of time variation. The bound is valid for a very general class of particle physics models and also holds in the presence of an unknown unmodulated background. More stringent bounds are obtained, if modest assumptions on symmetry properties of the DM halo are adopted. We illustrate the bounds by applying them to the annual modulation signals reported by the DAMA and CoGeNT experiments in the framework…
Initial state radiation experiment at MAMI
2014
In an attempt to contribute further insight into the discrepancy between the Lamb shift and elastic scattering determinations of the proton charge radius, a new experiment at MAMI is underway, aimed at measuring proton form-factors at very low momentum transfers by using a new technique based on initial state radiation. This paper reports on the conclusions of the pilot measurement performed in 2010, whose main goal was to check the feasibility of the proposed experiment and to recognize and overcome any obstacles before running the full experiment. The modifications to the experimental apparatus are then explained which significantly improved the quality of data collected in the full scale…
On the Mechanism of Low Frequency Bioelectromagnetism
2008
Results of investigations using simple physical models were presented. It is shown that physically exist small models that intensified low frequency electromagnetic field (EM). There are individual modes with definite symmetry. In the model cases we need some small background field for generations but in biological systems maybe there is some stabilizations factor. Experimental results and their biophysical aspects were discussed.