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Nonlinear dynamics

Rui Zhang, Kenneth S Schweizer
The Elastically Collective Nonlinear Langevin Equation theory for one-component viscous liquids and suspensions is generalized to treat coupled slow activated relaxation and diffusion in glass-forming binary sphere mixtures of any composition, size ratio and inter-particle interactions. A trajectory-level dynamical coupling parameter concept is introduced to construct two coupled dynamic free energy functions for the smaller penetrant and larger matrix particle. A two-step dynamical picture is proposed where the first step process involves matrix-facilitated penetrant hopping quantified in a self-consistent manner based on a temporal coincidence condition...
January 18, 2018: Journal of Physical Chemistry. B
Luciano Mescia, Michele A Chiapperino, Pietro Bia, Johan Gielis, Diego Caratelli
During the past decades, the poration of cell membrane induced by pulsed electric fields has been widely investigated. Since the basic mechanisms of this process have not yet been fully clarified, many research activities are focused on the development of suitable theoretical and numerical models. To this end, a nonlinear, nonlocal, dispersive, and space-time numerical algorithm has been developed and adopted to evaluate the transmembrane voltage and pore density along the perimeter of realistic irregularly shaped cells...
February 2018: IEEE Transactions on Bio-medical Engineering
Jose M G Vilar, J Miguel Rubi
Environmental fluctuations, such as changing conditions and variable nutrient availability, are an unavoidable component of the dynamics of virtually all populations. They affect populations in ways that are often difficult to predict and sometimes lead to paradoxical outcomes. Here, we present a general analytical approach to examine how populations respond to fluctuations. We show that there exist general explicit conditions that determine to what extent fluctuations propagate to the variability of the responses and how they change the behavior of the system, including whether they promote proliferation or death and whether they facilitate coexistence or exclusion of competing species...
January 17, 2018: Scientific Reports
Jun Ma, Ping Zhou, Bashir Ahmad, Guodong Ren, Chunni Wang
In this paper, a new four-variable dynamical system is proposed to set chaotic circuit composed of memristor and Josephson junction, and the dependence of chaotic behaviors on nonlinearity is investigated. A magnetic flux-controlled memristor is used to couple with the RCL-shunted junction circuit, and the dynamical behaviors can be modulated by changing the coupling intensity between the memristor and the RCL-shunted junction. Bifurcation diagram and Lyapunov exponent are calculated to confirm the emergence of chaos in the improved dynamical system...
2018: PloS One
Giovanni Dematteis, Tobias Grafke, Eric Vanden-Eijnden
The appearance of rogue waves in deep sea is investigated by using the modified nonlinear Schrödinger (MNLS) equation in one spatial dimension with random initial conditions that are assumed to be normally distributed, with a spectrum approximating realistic conditions of a unidirectional sea state. It is shown that one can use the incomplete information contained in this spectrum as prior and supplement this information with the MNLS dynamics to reliably estimate the probability distribution of the sea surface elevation far in the tail at later times...
January 16, 2018: Proceedings of the National Academy of Sciences of the United States of America
Chloe Audebert, Irene E Vignon-Clementel
The indocyanine green (ICG) clearance, presented as plasma disappearance rate is, presently, a reliable method to estimate the hepatic "function". However, this technique is not instantaneously available and thus cannot been used intra-operatively (during liver surgery). Near-infrared spectroscopy enables to assess hepatic ICG concentration over time in the liver tissue. This article proposes to extract more information from the liver intensity dynamics by interpreting it through a dedicated pharmacokinetics model...
January 12, 2018: European Journal of Pharmaceutical Sciences
Vrishti M Phadumdeo, Seth H Weinberg
Heart rate continuously varies due to autonomic regulation, stochasticity in pacemaking, and circadian rhythm, collectively termed heart rate variability (HRV), during normal physiological conditions. Low HRV is clinically associated with an elevated risk of cardiac arrhythmias. Alternans, a beat-to-beat alternation in action potential duration (APD) and/or intracellular calcium (Ca) transient, is a well-known risk factor associated with cardiac arrhythmias that is typically studied under conditions of a constant pacing rate, i...
January 11, 2018: Journal of Theoretical Biology
Jianjun Luo, Caisheng Wei, Honghua Dai, Zeyang Yin, Xing Wei, Jianping Yuan
In this paper, a robust inertia-free attitude takeover control scheme with guaranteed prescribed performance is investigated for postcapture combined spacecraft with consideration of unmeasurable states, unknown inertial property and external disturbance torque. Firstly, to estimate the unavailable angular velocity of combination accurately, a novel finite-time-convergent tracking differentiator is developed with a quite computationally achievable structure free from the unknown nonlinear dynamics of combined spacecraft...
January 11, 2018: ISA Transactions
Falin Tian, Tongtao Yue, Wei Dong, Xin Yi, Xianren Zhang
Membrane nanotubes play important functional roles in numerous cell activities such as cellular transport and communication. By exerting an external pulling force over a finite region in a membrane patch, here we investigate the size dependence of the membrane nanotube formation under the continuum and atomistic modeling frameworks. It is shown that the membrane undergoes a discontinuous shape transition as the size of the pulling region and the membrane tension increase. A formula characterizing the nonlinear relationship between the maximum static pulling force and pulling size is identified...
January 16, 2018: Physical Chemistry Chemical Physics: PCCP
Eric Smith, Supriya Krishnamurthy
Stochastic chemical reaction networks (CRNs) are complex systems that combine the features of concurrent transformation of multiple variables in each elementary reaction event and nonlinear relations between states and their rates of change. Most general results concerning CRNs are limited to restricted cases where a topological characteristic known as deficiency takes a value 0 or 1, implying uniqueness and positivity of steady states and surprising, low-information forms for their associated probability distributions...
December 2017: Physical Review. E
Naji Alibeji, Nicholas Kirsch, Brad E Dicianno, Nitin Sharma
A widely accepted model of muscle force generation during neuromuscular electrical stimulation (NMES) is a second-order nonlinear musculoskeletal dynamics cascaded to a delayed first-order muscle activation dynamics. However, most nonlinear NMES control methods have either neglected the muscle activation dynamics or used an ad hoc strategies to tackle the muscle activation dynamics, which may not guarantee control stability. We hypothesized that a nonlinear control design that includes muscle activation dynamics can improve the control performance...
August 2017: IEEE/ASME Transactions on Mechatronics
Ming-Liang Ren, Jacob S Berger, Wenjing Liu, Gerui Liu, Ritesh Agarwal
Dynamic control of nonlinear signals is critical for a wide variety of optoelectronic applications, such as signal processing for optical computing. However, controlling nonlinear optical signals with large modulation strengths and near-perfect contrast remains a challenging problem due to intrinsic second-order nonlinear coefficients via bulk or surface contributions. Here, via electrical control, we turn on and tune second-order nonlinear coefficients in semiconducting CdS nanobelts from zero to up to 151 pm V-1, a value higher than other intrinsic nonlinear coefficients in CdS...
January 15, 2018: Nature Communications
Ekrem Aydiner
In this study, we consider nonlinear interactions between components such as dark energy, dark matter, matter and radiation in the framework of the Friedman-Robertson-Walker space-time and propose a simple interaction model based on the time evolution of the densities of these components. By using this model we show that these interactions can be given by Lotka-Volterra type equations. We numerically solve these coupling equations and show that interaction dynamics between dark energy-dark matter-matter or dark energy-dark matter-matter-radiation has a strange attractor for 0 > w de  >-1, w dm  ≥ 0, w m  ≥ 0 and w r  ≥ 0 values...
January 15, 2018: Scientific Reports
Stéphanie Ratté, Sergei Karnup, Steven A Prescott
Persistent spiking - the continuation of spiking after a stimulus ends - is thought to support working memory. Muscarinic receptor activation enables persistent spiking among synaptically isolated pyramidal neurons in anterior cingulate cortex (ACC) but a detailed characterization of that spiking is lacking and the underlying mechanisms remain unclear. Here we show that the rate of persistent spiking in ACC neurons is insensitive to the intensity and number of triggers but can be modulated by injected current, and that persistent spiking can resume after several seconds of hyperpolarization-imposed quiescence...
January 15, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Wojciech Radosz, Grzegorz Pawlik, Antoni Mitus
We study theoretically the kinetics of non-interacting photo-switchable guest molecules (model azo-dye) dispersed at low concentration in host (model polymer matrix) in the all-optical poling process close to the glass transition temperature Tg. We modify kinetic Monte Carlo model used in our previous studies of nonlinear optical processes in host-guest systems. The polymer matrix is simulated using the bond-fluctuation model. The kinetics of multiple trans-cis-trans cycles is formulated in terms of transition probabilities which depend on local free volume in the matrix and its dynamics...
January 15, 2018: Journal of Physical Chemistry. B
Mohammad Taghinejad, Hossein Taghinejad, Zihao Xu, Yawei Liu, Sean P Rodrigues, Kyu-Tae Lee, Tianquan Lian, Ali Adibi, Wenshan Cai
The optical Kerr nonlinearity of plasmonic metals provides enticing prospects for developing reconfigurable and ultracompact all-optical modulators. In nanostructured metals, the coherent coupling of light energy to plasmon resonances creates a nonequilibrium electron distribution at an elevated electron temperature that gives rise to significant Kerr optical nonlinearities. Although enhanced nonlinear responses of metals facilitate the realization of efficient modulation devices, the intrinsically slow relaxation dynamics of the photoexcited carriers, primarily governed by electron-phonon interactions, impedes ultrafast all-optical modulation...
January 15, 2018: Advanced Materials
Q Fu, D H Wang, L Xu, G Yuan
Nonlinear oscillators are usually utilized by bionic scientists for establishing central pattern generator models for imitating rhythmic motions by bionic scientists. In the natural word, many rhythmic motions possess asymmetric time ratios, which means that the forward and the backward motions of an oscillating process sustain different times within one period. In order to model rhythmic motions with asymmetric time ratios, nonlinear oscillators with asymmetric forward and backward trajectories within one period should be studied...
January 13, 2018: Biological Cybernetics
Satoshi Inoue, Kanya Kusano, Jörg Büchner, Jan Skála
Solar eruptions are well-known drivers of extreme space weather, which can greatly disturb the Earth's magnetosphere and ionosphere. The triggering process and initial dynamics of these eruptions are still an area of intense study. Here we perform a magnetohydrodynamic simulation taking into account the observed photospheric magnetic field to reveal the dynamics of a solar eruption in a real magnetic environment. In our simulation, we confirmed that tether-cutting reconnection occurring locally above the polarity inversion line creates a twisted flux tube, which is lifted into a toroidal unstable area where it loses equilibrium, destroying the force-free state, and driving the eruption...
January 12, 2018: Nature Communications
Carlos A R Herdeiro, Eugen Radu
East and Pretorius have successfully evolved, using fully nonlinear numerical simulations, the superradiant instability of the Kerr black hole (BH) triggered by a massive, complex vector field. Evolutions terminate in stationary states of a vector field condensate synchronized with a rotating BH horizon. We show that these end points are fundamental states of Kerr BHs with synchronized Proca hair. Motivated by the "experimental data" from these simulations, we suggest a universal (i.e., field-spin independent), analytic model for the subset of BHs with synchronized hair that possess a quasi-Kerr horizon, applicable in the weak hair regime...
December 29, 2017: Physical Review Letters
Isaac Klickstein, Afroza Shirin, Francesco Sorrentino
It has recently been shown that the minimum energy solution of the control problem for a linear system produces a control trajectory that is nonlocal. An issue then arises when the dynamics represents a linearization of the underlying nonlinear dynamics of the system where the linearization is only valid in a local region of the state space. Here we provide a solution to the problem of optimally controlling a linearized system by deriving a time-varying set that represents all possible control trajectories parametrized by time and energy...
December 29, 2017: Physical Review Letters
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