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Nonlinear dynamics

Ji Who Kim, Seongho Seo, Hyeon Sik Kim, Dong-Yeon Kim, Ho-Young Lee, Keon Wook Kang, Dong Soo Lee, Hee-Seung Bom, Jung-Joon Min, Jae Sung Lee
OBJECTIVE: ((18)F-fluoropentyl)triphenylphosphonium salt ((18)F-FPTP) is a new promising myocardial PET imaging tracer. It shows high accumulation in cardiomyocytes and rapid clearance from liver. We performed compartmental analysis of (18)F-FPTP PET images in rat and evaluated two linear analyses: linear least-squares (LLS) and a basis function method (BFM) for generating parametric images. The minimum dynamic scan duration for kinetic analysis was also investigated and computer simulation undertaken...
April 25, 2017: Annals of Nuclear Medicine
Kai Liu, Gary R Marple, Jun Allard, Shuwang Li, Shravan Veerapaneni, John Lowengrub
We study the fully nonlinear, nonlocal dynamics of two-dimensional multicomponent vesicles in a shear flow with matched viscosity of the inner and outer fluids. Using a nonstiff, pseudo-spectral boundary integral method, we investigate dynamical patterns induced by inhomogeneous bending for a two phase system. Numerical results reveal that there exist novel phase-treading and tumbling mechanisms that cannot be observed for a homogeneous vesicle. In particular, unlike the well-known steady tank-treading dynamics characterized by a fixed inclination angle, here the phase-treading mechanism leads to unsteady periodic dynamics with an oscillatory inclination angle...
April 25, 2017: Soft Matter
Mehdi Taheri, Farid Sheikholeslam, Majddedin Najafi, Maryam Zekri
In this paper, consensus problem is considered for second order multi-agent systems with unknown nonlinear dynamics under undirected graphs. A novel distributed control strategy is suggested for leaderless systems based on adaptive fuzzy wavelet networks. Adaptive fuzzy wavelet networks are employed to compensate for the effect of unknown nonlinear dynamics. Moreover, the proposed method is developed for leader following systems and leader following systems with state time delays. Lyapunov functions are applied to prove uniformly ultimately bounded stability of closed loop systems and to obtain adaptive laws...
April 21, 2017: ISA Transactions
M A Eftekhar, L G Wright, M S Mills, M Kolesik, R Amezcua Correa, F W Wise, D N Christodoulides
We demonstrate that the pump's spatial input profile can provide additional degrees of freedom in tailoring at will the nonlinear dynamics and the ensuing spectral content of supercontinuum generation in highly multimoded optical fibers. Experiments and simulations carried out at 1550 nm indicate that the modal composition of the input beam can substantially alter the soliton fission process as well as the resulting Raman and dispersive wave generation that eventually lead to supercontinuum in such a multimode environment...
April 17, 2017: Optics Express
Bowen Li, Ying Yu, Xiaoming Wei, Yiqing Xu, Kevin K Tsia, Kenneth K Y Wong
Fiber-stretcher based phase-lock loop (PLL) is a mature technique in fiber mode-locked lasers for repetition-rate stabilization. However, undesired side effects may be induced if not properly handled, which is easily overlooked owing to the lack of single-shot spectral analyzers. Thanks to the ultrafast spectral analyzing capability of optical time-stretch, an intriguing spectral dynamics is observed in a repetition-rate-stabilized nonlinear polarization rotation (NPR) mode-locked laser. Under the dynamic state, the optical spectra of pulses undergo dramatic evolution in every round trip while the pulse energy is relatively constant...
April 17, 2017: Optics Express
Liao Chen, Yuhua Duan, Haidong Zhou, Xi Zhou, Chi Zhang, Xinliang Zhang
A real-time broadband radio frequency (RF) spectrum analyzer is proposed and experimentally demonstrated to rapidly measure the RF spectrum of broadband optical signal. Cross phase modulation in the highly-nonlinear fiber is used to convert the RF spectrum carried by the pump to the optical spectrum of the probe signal, then the optical spectrum is real-time analyzed with the parametric spectro-temporal analyzer (PASTA) technology. The system performances are investigated in detail, including bandwidth, resolution, frame rate, and dynamic range...
April 17, 2017: Optics Express
Mimma Nardelli, Alberto Greco, Juan Bolea, Gaetano Valenza, Enzo Pasquale Scilingo, Raquel Bailon
The number of studies about ultra-short cardiovascular time series is increasing because of the demand for mobile applications in telemedicine and e-health monitoring. However, the current literature still needs a proper validation of heartbeat nonlinear dynamics assessment from ultra-short time series. This paper reports on the reliability of the Lagged Poincaré Plot (LPP) parameters - calculated from ultra-short cardiovascular time series. Reliability is studied on simulated as well as on real RR series...
April 18, 2017: IEEE Journal of Biomedical and Health Informatics
Yajun Zhang, Tianyou Chai, Hong Wang, Dianhui Wang, Xinkai Chen
Complex industrial processes are multivariable and generally exhibit strong coupling among their control loops with heavy nonlinear nature. These make it very difficult to obtain an accurate model. As a result, the conventional and data-driven control methods are difficult to apply. Using a twin-tank level control system as an example, a novel multivariable decoupling control algorithm with adaptive neural-fuzzy inference system (ANFIS)-based unmodeled dynamics (UD) compensation is proposed in this paper for a class of complex industrial processes...
April 24, 2017: IEEE Transactions on Neural Networks and Learning Systems
Addison J Schile, Ward H Thompson
Linear response approximations are central to our understanding and simulations of nonequilibrium statistical mechanics. Despite the success of these approaches in predicting nonequilibrium dynamics, open questions remain. Laird and Thompson [J. Chem. Phys. 126, 211104 (2007)] previously formalized, in the context of solvation dynamics, the connection between the static linear-response approximation and the assumption of Gaussian statistics. The Gaussian statistics perspective is useful in understanding why linear response approximations are still accurate for perturbations much larger than thermal energies...
April 21, 2017: Journal of Chemical Physics
Gui-Hua Li, Yong-Xin Zhang
The transmission of infectious diseases has been studied by mathematical methods since 1760s, among which SIR model shows its advantage in its epidemiological description of spread mechanisms. Here we established a modified SIR model with nonlinear incidence and recovery rates, to understand the influence by any government intervention and hospitalization condition variation in the spread of diseases. By analyzing the existence and stability of the equilibria, we found that the basic reproduction number [Formula: see text] is not a threshold parameter, and our model undergoes backward bifurcation when there is limited number of hospital beds...
2017: PloS One
Thomas Hillen, Diana White, Gerda de Vries, Adriana Dawes
Microtubules (MTs) are protein filaments that provide structure to the cytoskeleton of cells and a platform for the movement of intracellular substances. The spatial organization of MTs is crucial for a cell's form and function. MTs interact with a class of proteins called motor proteins that can transport and position individual filaments, thus contributing to overall organization. In this paper, we study the mathematical properties of a coupled partial differential equation (PDE) model, introduced by White et al...
April 20, 2017: Journal of Biological Dynamics
Zohreh Moallem, Azadeh Karimi-Malati, Ahad Sahragard, Arash Zibaee
Development of Glyphodes pyloalis Walker was studied under laboratory conditions at constant temperatures of 12, 16, 20, 24, 28, 30, 32, and 36 °C. No development occurred at 36 °C. Although eggs hatched at 12 ºC, no larvae were capable of developing to adult stage. At 16 ºC, survival rate was low (4%) and prepupal stage lasted 101.68 ± 11.03 d. Larvae completed development through six stadia at 16, 30, and 32 °C. Developmental time of overall immature stages varied from 46.62 d at 20 °C to 22...
January 1, 2017: Journal of Insect Science
Tilo Schwalger, Moritz Deger, Wulfram Gerstner
Neural population equations such as neural mass or field models are widely used to study brain activity on a large scale. However, the relation of these models to the properties of single neurons is unclear. Here we derive an equation for several interacting populations at the mesoscopic scale starting from a microscopic model of randomly connected generalized integrate-and-fire neuron models. Each population consists of 50-2000 neurons of the same type but different populations account for different neuron types...
April 19, 2017: PLoS Computational Biology
Nathan Szanto, Vignesh Narayanan, Sarangapani Jagannathan
In this paper, a novel event-triggered implementation of a tracking controller for an uncertain strict-feedback system is presented. Neural networks (NNs) are utilized in the backstepping approach to design a control input by approximating unknown dynamics of the strict-feedback nonlinear system with event-sampled inputs. The system state vector is assumed to be unknown and an NN observer is used to estimate the state vector. By using the estimated state vector and backstepping design approach, an event-sampled controller is introduced...
April 12, 2017: IEEE Transactions on Neural Networks and Learning Systems
Francesca Locati, Germano Rossi, Laura Parolin
OBJECTIVE: Several authors have identified a bidirectional link between patient metacognitive functioning and the therapeutic alliance. Specifically, metacognition might be enhanced by a positive alliance with the clinician, whereas metacognitive deficits might impede the alliance. Interestingly, the therapist's technical interventions might influence both therapeutic alliance and metacognitive functioning. However, little is known about the interactions between these dimensions. The aim of the present study is to explore these interactions more fully in the earliest phase of the therapeutic process...
April 19, 2017: Psychotherapy Research: Journal of the Society for Psychotherapy Research
Jiang Wang, Mohit A Gayatri, Andrew L Ferguson
Asphaltenes constitute the heaviest fraction of the aromatic group in crude oil. Aggregation and precipitation of asphaltenes during petroleum processing costs the petroleum industry billions of dollars each year due to downtime and production inefficiencies. Asphaltene aggregation proceeds via a hierarchical self-assembly process that is well-described by the Yen-Mullins model. Nevertheless, the microscopic details of the emergent cluster morphologies and their relative stability under different processing conditions remain poorly understood...
April 26, 2017: Journal of Physical Chemistry. B
Makoto Ashino, Roland Wiesendanger
Bending at the nanometre scale can substantially modify the mechanical, chemical and electronic properties of graphene membranes. The subsequent response of chemical bonds leads to deviations from plate idealisation in continuum mechanics. However, those phenomena have thus far been investigated exclusively by measuring the electronic properties of graphene deformed by compressing and stretching with local-probe techniques. Here, we report that the interatomic-attractive forces applied on the convexly-curved graphene by the probe tip give rise to a pin-point breaking of the plate idealisation in the continuum mechanics, facilitating atomically-localised enhancements in its chemical reactivity and mechanical strength...
April 18, 2017: Scientific Reports
Jihua Fu, Xu Wang, Tao Wei, Meng Wei, Yang Shen
Observations of surface deformation are essential for understanding a wide range of geophysical problems, including earthquakes, volcanoes, landslides, and glaciers. Current geodetic technologies, such as global positioning system (GPS), interferometric synthetic aperture radar (InSAR), borehole and laser strainmeters, are costly and limited in their temporal or spatial resolutions. Here we present a new type of strainmeters based on the coaxial cable Bragg grating (CCBG) sensing technology that provides cost-effective strain measurements...
April 12, 2017: Sensors
Yannan Shen, P G Kevrekidis, G P Veldes, D J Frantzeskakis, D DiMarzio, X Lan, V Radisic
In the present work, we explore soliton and roguelike wave solutions in the transmission line analog of a nonlinear left-handed metamaterial. The nonlinearity is expressed through a voltage-dependent, symmetric capacitance motivated by recently developed ferroelectric barium strontium titanate thin-film capacitor designs. We develop both the corresponding nonlinear dynamical lattice and its reduction via a multiple scales expansion to a nonlinear Schrödinger (NLS) model for the envelope of a given carrier wave...
March 2017: Physical Review. E
Yoji Kawamura
We formulate a theory for the collective phase reduction of globally coupled noisy dynamical elements exhibiting macroscopic rhythms. We first transform the Langevin-type equation that represents a group of globally coupled noisy dynamical elements into the corresponding nonlinear Fokker-Planck equation and then develop the phase reduction method for limit-cycle solutions to the nonlinear Fokker-Planck equation. The theory enables us to describe the collective dynamics of a group of globally coupled noisy dynamical elements by a single degree of freedom called the collective phase...
March 2017: Physical Review. E
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