Physical Review E (PHYS REV E)

Publications in this journal

• Article: Distance weighted city growth

  Diego Rybski, Anselmo Garcia Cantu Ros, Jürgen P. Kropp
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  ABSTRACT: Urban agglomerations exhibit complex emergent features of which Zipf's law, i.e. a power-law size distribution, and fractality may be regarded as the most prominent ones. We propose a simplistic model for the generation of city-like structures which is solely based on the assumption that growth is more likely to take place close to inhabited space. The model involves one parameter which is an exponent determining how strongly the attraction decays with the distance. In addition, the model is run iteratively so that existing clusters can grow (together) and new ones can emerge. The model is capable of reproducing the size distribution and the fractality of the boundary of the largest cluster. While the power-law distribution depends on both, the imposed exponent and the iteration, the fractality seems to be independent of the former and only depends on the latter. Analyzing land-cover data we estimate the parameter-value $\gamma\approx 2.5$ for Paris and it's surroundings.
  Physical Review E 09/2013; 87(4):042114.
• Article: Log-amplitude statistics for Beck-Cohen superstatistics

  Ken Kiyono, Hidetoshi Konno
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  ABSTRACT: As a possible generalization of Beck-Cohen superstatistical processes, we study non-Gaussian processes with temporal heterogeneity of local variance. To characterize the variance heterogeneity, we define log-amplitude cumulants and log-amplitude autocovariance and derive closed-form expressions of the log-amplitude cumulants for χ^2, inverse χ^2, and log-normal superstatistical distributions. Furthermore, we show that χ^2 and inverse χ^2 superstatistics with degree 2 are closely related to an extreme value distribution, called the Gumbel distribution. In these cases, the corresponding superstatistical distributions result in the q-Gaussian distribution with q=5/3 and the bilateral exponential distribution, respectively. Thus, our finding provides a hypothesis that the asymptotic appearance of these two special distributions may be explained by a link with the asymptotic limit distributions involving extreme values. In addition, as an application of our approach, we demonstrated that non-Gaussian fluctuations observed in a stock index futures market can be well approximated by the χ^2 superstatistical distribution with degree 2.
  Physical Review E 05/2013; 87(5):052104.
• Article: Comparison between x-ray scattering and velocity-interferometry measurements from shocked liquid deuterium

  K. Falk, S. P. Regan, J. Vorberger, B. J. B. Crowley, S. H. Glenzer, S. X. Hu, C. D. Murphy, P. B. Radha, A. P. Jephcoat, J. S. Wark, D. O. Gericke, G. Gregori
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  ABSTRACT: The equation of state of light elements is essential to understand the structure of Jovian planets and inertial confinement fusion research. The Omega laser was used to drive a planar shock wave in the cryogenically cooled deuterium, creating warm dense matter conditions. X-ray scattering was used to determine the spectrum near the boundary of the collective and noncollective scattering regimes using a narrow band x-ray source in backscattering geometry. Our scattering spectra are thus sensitive to the individual electron motion as well as the collective plasma behavior and provide a measurement of the electron density, temperature, and ionization state. Our data are consistent with velocity-interferometry measurements previously taken on the same shocked deuterium conditions and presented by K. Falk et al. [High Energy Density Phys. 8, 76 (2012)]. This work presents a comparison of the two diagnostic systems and offers a detailed discussion of challenges encountered.
  Physical Review E 04/2013; 87(4):043112.
• Article: Topology-free design for amplitude death in time-delayed oscillators coupled by a delayed connection

  Luan Ba Le, Keiji Konishi, Naoyuki Hara
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  ABSTRACT: This paper deals with amplitude death in time-delayed oscillators coupled by a delayed connection with topology uncertainty. A systematic procedure without trial-and-error testing for designing connection parameters is proposed from a robust control theory viewpoint. This procedure has the following two advantages: the designed connection parameters are valid for any network topology and the procedure is valid even for long-delay oscillators. These analytical results are verified by some numerical simulations.
  Physical Review E 04/2013; 87(4):042908.
• Article: Irregular excitation patterns in reaction-diffusion systems due to perturbation by secondary pacemakers

  Claudia Lenk, Mario einax, Philipp Maass
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  ABSTRACT: Spatiotemporal excitation patterns in the FitzHugh-Nagumo model are studied, which result from the disturbance of a primary pacemaker by a secondary pacemaker. The primary and secondary pacemakers generate regular waves with frequencies fpace and fpert, respectively. The pacemakers are spatially separated, but waves emanating from them encounter each other via a small bridge. This leads to three different types I–III of irregular excitation patterns in disjunct domains of the fpace-fpert plane. Types I and II are caused by detachments of waves coming from the two pacemakers at corners of the bridge. Type III irregularities are confined to a boundary region of the system and originate from a partial penetration of the primary waves into a space, where circular wave fronts from the secondary pacemaker prevail. For this type, local frequencies can significantly exceed fpace and fpert. The degree of irregularity found for the three different types is quantified by the entropy of the local frequency distribution and an order parameter for phase coherence.
  Physical Review E 04/2013; 87(4):042904.
• Article: Mode competition in cylindrical flows driven by sidewall oscillations

  Carles Panades, Francisco Marques, Alvaro Meseguer
  Physical Review E 04/2013; 87(4):043001.
• Article: Fluctuations and correlations of a driven tracer in a hard-core lattice gas

  Olivier Benichou, Pierre Illien, Gleb Oshanin, Raphael Voituriez
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  ABSTRACT: We consider a driven tracer particle (TP) in a bath of hard-core particles undergoing continuous exchanges with a reservoir. We develop an analytical framework which allows us to go beyond the standard force-velocity relation used for this minimal model of active microrheology and quantitatively analyze, for any density of the bath particles, the fluctuations of the TP position and their correlations with the occupation number of the bath particles. We obtain an exact Einstein-type relation which links these fluctuations in the absence of a driving force and the bath particles density profiles in the linear driving regime. For the one-dimensional case we also provide an approximate but very accurate explicit expression for the variance of the TP position and show that it can be a non-monotoneous function of the bath particles density: counter-intuitively, an increase of the density may increase the dispersion of the TP position. We show that this non trivial behavior, which could in principle be observed in active microrheology experiments, is induced by subtle cross-correlations quantified by our approach.
  Physical Review E 03/2013; 87:032164.
• Article: On ergodic least-squares estimators of the generalized diffusion coefficient for fractional Brownian motion

  Denis Boyer, David S. Dean, Carlos Mejia-Monasterio, Gleb Oshanin
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  ABSTRACT: We analyse a class of estimators of the generalized diffusion coefficient for fractional Brownian motion $B_t$ of known Hurst index $H$, based on weighted functionals of the single time square displacement. We show that for a certain choice of the weight function these functionals possess an ergodic property and thus provide the true, ensemble-averaged, generalized diffusion coefficient to any necessary precision from a single trajectory data, but at expense of a progressively higher experimental resolution. Convergence is fastest around $H\simeq0.30$, a value in the subdiffusive regime.
  Physical Review E 03/2013; 87:030103.
• Article: Directional sensing by cooperative chemoreceptor arrays modeled as Monod-Wyman-Changeux clusters

  Jin Yang
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  ABSTRACT: Most sensory cells use transmembrane chemoreceptors to detect chemical signals in the environment. The biochemical properties and spatial organization of chemoreceptors play important roles in achieving and maintaining sensitivity and accuracy of chemical sensing. Here we investigate the effects of receptor cooperativity and adaptation on the physical limits for sensing a chemical gradient. We study a single cell with aggregated chemoreceptor arrays on the cell surface and derive a general formula to the limits for gradient sensing from the uncertainty of instantaneous receptor activity. In comparison to independent receptors, we find that cooperativity by nonadaptive receptors could significantly lower the sensing limits in a chemical concentration range determined by the biochemical properties of ligand-receptor binding and ligand-induced receptor activity. Cooperativity by adaptive receptors is beneficial to gradient sensing within a broad range of background concentrations. Our results also show that the isotropic receptor aggregate layout on the cell surface represents an optimal configuration for gradient sensing.
  Physical Review E 03/2013; 87(3):032718.
• Article: Fluctuation theorems for non-Markovian quantum processes

  Bruno Leggio, Anna Napoli, Heinz-Peter Breuer, Antonino Messina
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  ABSTRACT: Exploiting previous results on Markovian dynamics and fluctuation theorems, we study the consequences of memory effects on single realizations of nonequilibrium processes within an open system approach. The entropy production along single trajectories for forward and backward processes is obtained with the help of a recently proposed classical-like non-Markovian stochastic unravelling, which is demonstrated to lead to a correction of the standard entropic fluctuation theorem. This correction is interpreted as resulting from the interplay between the information extracted from the system through measurements and the flow of information from the environment to the open system: Due to memory effects single realizations of a dynamical process are no longer independent, and their correlations fundamentally affect the behavior of entropy fluctuations.
  Physical Review E 03/2013; 87:032113.
• Article: Limit of strong ion coupling due to electron shielding

  M. Lyon, S. D. Bergeson, M. S. Murillo
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  ABSTRACT: We show that strong coupling between ions in an ultracold neutral plasma is limited by electron screening. While electron screening reduces the quasi-equilibrium ion temperature, it also reduces the ion-ion electrical potential energy. The net result is that the ratio of nearest-neighbor potential energy to kinetic energy in quasi-equilibrium is constant and limited to approximately 2 unless the electrons are heated by some external source. We support these conclusions by reporting new measurements of the ion velocity distribution in an ultracold neutral calcium plasma. These results match previously reported simulations of Yukawa systems. Theoretical considerations are used to determine the screened nearest-neighbor potential energy in the plasma.
  Physical Review E 03/2013; 87:033101.
• Article: Linear response theory for two neural populations applied to gamma oscillation generation

  Alexandre Payeur, Jérémie Lefebvre, Leonard Maler, André Longtin
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  ABSTRACT: Linear response theory (LRT) can be used to compute spectral properties of single and populations of stochastic leaky integrate-and-fire neurons. The effects of inputs, both external and from delayed feedback, can be modeled within that theory when the neural function is sufficiently linearized by noise. It has been used to explain experiments where gamma oscillations are induced by spatially correlated stochastic inputs to a network with delayed inhibitory feedback. Here we expand this theory to include two distinct population types. We first show how to deal with homogeneous networks where both types of neurons have identical intrinsic properties. We further tackle the asymmetric case, where noise or bias differ. We also analyze the case where the membrane time constants differ, based on experimental evidence, which requires delicate alterations of the theory. We directly apply the theory to networks of ON and OFF cells in the electrosensory system, which together provide global delayed negative feedback to all cells; however, ON and OFF cells receive external inputs of opposite polarities. Theoretical results are in excellent agreement with numerical simulations of the two population network. In contrast to the case of a single ON cell population with feedback, the more realistic presence of both cell types can significantly reduce the propensity of the delayed feedback network to oscillate for spatially correlated inputs. Our results are further linked to recent predictions from deterministic neural field theory. Among other findings, our work suggests that the observed gamma oscillations could be explained only if the ON and OFF cell feedback pathways are anatomically segregated. Thus our two population LRT can make specific predictions about network topography in specific systems.
  Physical Review E 03/2013; 87(3):032703.