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Benjamin Ballnus, Sabine Hug, Kathrin Hatz, Linus Görlitz, Jan Hasenauer, Fabian J Theis
BACKGROUND: In quantitative biology, mathematical models are used to describe and analyze biological processes. The parameters of these models are usually unknown and need to be estimated from experimental data using statistical methods. In particular, Markov chain Monte Carlo (MCMC) methods have become increasingly popular as they allow for a rigorous analysis of parameter and prediction uncertainties without the need for assuming parameter identifiability or removing non-identifiable parameters...
June 24, 2017: BMC Systems Biology
Asger M Haugaard
Predicting extrema of chaotic systems in high-dimensional phase space remains a challenge. Methods, which give extrema that are valid in the long term, have thus far been restricted to models of only a few variables. Here, a method is presented which treats extrema of chaotic systems as belonging to discretised manifolds of low dimension (low-D) embedded in high-dimensional (high-D) phase space. As a central feature, the method exploits that strange attractor dimension is generally much smaller than parent system phase space dimension...
2017: PloS One
J Dai, L Z Leng, C F Lu, F Gong, S P Zhang, W Zheng, G X Lu, G Lin
PURPOSE: The purpose of this study was to investigate the cause of repeated multipronucleus (MPN) formation in zygotes in a patient after both in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI). METHOD: This is a case study. A patient had unexplained primary infertility with recurring total MPN zygotes after IVF and ICSI cycles. Time-lapse monitoring of pronucleus formation was carried out. Embryos developed from MPN zygotes were analyzed by fluorescence in situ hybridization (FISH)...
June 22, 2017: Journal of Assisted Reproduction and Genetics
Nguyen Viet Hung, Krzysztof Zegadlo, Aliaksandr Ramaniuk, Vladimir V Konotop, Marek Trippenbach
We consider a nanostructure of two coupled ring waveguides with constant linear gain and nonlinear absorption - the system that can be implemented in various settings including polariton condensates, optical waveguides or atomic Bose-Einstein condensates. It is found that, depending on the parameters, this simple configuration allows for observing several complex nonlinear phenomena, which include spontaneous symmetry breaking, modulational instability leading to generation of stable circular flows with various vorticities, stable inhomogeneous states with interesting structure of currents flowing between rings, as well as dynamical regimes having signatures of chaotic behavior...
June 22, 2017: Scientific Reports
Karen M Hampson, Matthew P Cufflin, Edward A H Mallen
When fixating on a stationary object, the power of the eye's lens fluctuates. Studies have suggested that changes in these so-called microfluctuations in accommodation may be a factor in the onset and progression of short-sightedness. Like many physiological signals, the fluctuations in the power of the lens exhibit chaotic behaviour. A breakdown or reduction in chaos in physiological systems indicates stress to the system or pathology. The purpose of this study was to determine whether the chaos in fluctuations of the power of the lens changes with refractive error, i...
June 21, 2017: Bulletin of Mathematical Biology
Chi-Maw Lin, Cheng-Ping Wang, Chun-Nan Chen, Che-Yi Lin, Ting-Yi Li, Chen-Han Chou, Ya-Ching Hsu, Po-Yen Kuo, Tsung-Lin Yang, Pei-Jen Lou, Jenq-Yuh Ko, Tseng-Cheng Chen
Early detection of neck lymph node (LN) recurrence is paramount in improving the prognosis of treated head and neck cancer patients. Ultrasound (US) with US-guided fine needle aspiration (FNA) and core needle biopsy (CNB) have been shown to have great accuracy for LN diagnoses in the untreated neck. However, in the treated neck with fibrosis, their roles are not clarified. Here, we retrospectively review 153 treated head and neck cancer patients who had received US and US-guided FNA/CNB. In multivariate logistic regression analyses, size (short-axis diameter >0...
June 21, 2017: Scientific Reports
Gil Ariel, Avraham Be'er, Andy Reynolds
We describe a new mechanism for Lévy walks, explaining the recently observed superdiffusion of swarming bacteria. The model hinges on several key physical properties of bacteria, such as an elongated cell shape, self-propulsion, and a collectively generated regular vortexlike flow. In particular, chaos and Lévy walking are a consequence of group dynamics. The model explains how cells can fine-tune the geometric properties of their trajectories. Experiments confirm the spectrum of these patterns in fluorescently labeled swarming Bacillus subtilis...
June 2, 2017: Physical Review Letters
Akira Akaishi, Kazuki Aoki, Akira Shudo
We have studied a two-dimensional piecewise linear map to examine how the hierarchical structure of stable regions affects the slow dynamics in Hamiltonian systems. In the phase space there are infinitely many stable regions, each of which is polygonal-shaped, and the rest is occupied by chaotic orbits. By using symbolic representation of stable regions, a procedure to compute the edges of the polygons is presented. The stable regions are hierarchically distributed in phase space and the edges of the stable regions show the marginal instability...
May 2017: Physical Review. E
R Chacón, A Martínez García-Hoz, J A Martínez
We study the effectiveness of locally controlling the impulse transmitted by parametric periodic excitations at inducing and suppressing chaos in starlike networks of driven damped pendula, leading to asynchronous chaotic states and equilibria, respectively. We found that the inducing (suppressor) effect of increasing (decreasing) the impulse transmitted by the parametric excitations acting on particular nodes depends strongly on their number and degree of connectivity as well as the coupling strength. Additionally, we provide a theoretical analysis explaining the basic physical mechanisms of the emergence and suppression of chaos as well as the main features of the chaos-control scenario...
May 2017: Physical Review. E
Marcello A Budroni, Andrea Baronchelli, Romualdo Pastor-Satorras
Methods connecting dynamical systems and graph theory have attracted increasing interest in the past few years, with applications ranging from a detailed comparison of different kinds of dynamics to the characterization of empirical data. Here we investigate the effects of the (multi)fractal properties of a signal, common in time series arising from chaotic dynamics or strange attractors, on the topology of a suitably projected network. Relying on the box-counting formalism, we map boxes into the nodes of a network and establish analytic expressions connecting the natural measure of a box with its degree in the graph representation...
May 2017: Physical Review. E
Barbara Dietz, Vitalii Yunko, Małgorzata Białous, Szymon Bauch, Michał Ławniczak, Leszek Sirko
We present experimental and numerical results for the long-range fluctuation properties in the spectra of quantum graphs with chaotic classical dynamics and preserved time-reversal invariance. Such systems are generally believed to provide an ideal basis for the experimental study of problems originating from the field of quantum chaos and random matrix theory. Our objective is to demonstrate that this is true only for short-range fluctuation properties in the spectra, whereas the observation of deviations in the long-range fluctuations is typical for quantum graphs...
May 2017: Physical Review. E
Hongbin Fang, Suyi Li, Huimin Ji, K W Wang
Origami-inspired structures and materials have shown extraordinary properties and performances originating from the intricate geometries of folding. However, current state of the art studies have mostly focused on static and quasistatic characteristics. This research performs a comprehensive experimental and analytical study on the dynamics of origami folding through investigating a stacked Miura-Ori (SMO) structure with intrinsic bistability. We fabricate and experimentally investigated a bistable SMO prototype with rigid facets and flexible crease lines...
May 2017: Physical Review. E
Manuel Jiménez-Martín, Javier Rodríguez-Laguna, Otti D'Huys, Javier de la Rubia, Elka Korutcheva
We study the synchronization of chaotic units connected through time-delayed fluctuating interactions. Focusing on small-world networks of Bernoulli and Logistic units with a fixed chiral backbone, we compare the synchronization properties of static and fluctuating networks in the regime of large delays. We find that random network switching may enhance the stability of synchronized states. Synchronization appears to be maximally stable when fluctuations are much faster than the time-delay, whereas it disappears for very slow fluctuations...
May 2017: Physical Review. E
Deterlino Urzagasti, David Laroze, Harald Pleiner
We study two-dimensional localized patterns in weakly dissipative systems that are driven parametrically. As a generic model for many different physical situations we use a generalized nonlinear Schrödinger equation that contains parametric forcing, damping, and spatial coupling. The latter allows for the existence of localized pattern states, where a finite-amplitude uniform state coexists with an inhomogeneous one. In particular, we study numerically two-dimensional patterns. Increasing the driving forces, first the localized pattern dynamics is regular, becomes chaotic for stronger driving, and finally extends in area to cover almost the whole system...
May 2017: Physical Review. E
Ignacio García-Mata, Augusto J Roncaglia, Diego A Wisniacki
The work distribution is a fundamental quantity in nonequilibrium thermodynamics mainly due to its connection with fluctuation theorems. Here, we develop a semiclassical approximation to the work distribution for a quench process in chaotic systems that provides a link between the quantum and classical work distributions. The approach is based on the dephasing representation of the quantum Loschmidt echo and on the quantum ergodic conjecture, which states that the Wigner function of a typical eigenstate of a classically chaotic Hamiltonian is equidistributed on the energy shell...
May 2017: Physical Review. E
Gaspar Cano, Rui Dilão
We show that action potentials in the Hodgkin-Huxley neuron model result from a type I intermittency phenomenon that occurs in the proximity of a saddle-node bifurcation of limit cycles. For the Hodgkin-Huxley spatially extended model, describing propagation of action potential along axons, we show the existence of type I intermittency and a new type of chaotic intermittency, as well as space propagating regular and chaotic diffusion waves. Chaotic intermittency occurs in the transition from a turbulent regime to the resting regime of the transmembrane potential and is characterised by the existence of a sequence of action potential spikes occurring at irregular time intervals...
June 14, 2017: Journal of Computational Neuroscience
Salomón Sanabria-Urbán, Hojun Song, Ken Oyama, Antonio González-Rodríguez, Raúl Cueva Del Castillo
The genus Sphenarium Charpentier, 1842 comprises the most diverse group of the New World Pyrgomorphidae. These grasshoppers show an extensive variation in external morphology, and are culturally and economically important for Mexican people since pre-Hispanic times. Nevertheless, the taxonomy of Sphenarium has been chaotic and remained incompletely resolved until now. Following an integrative taxonomic framework, we infer the number of species in this genus by species delimitation based on morphological, phylogenetic, and geographic information...
June 8, 2017: Zootaxa
Jorge Duarte, Cristina Januario, Nuno Martins
Nonlinear systems are commonly able to display abrupt qualitative changes (or transitions) in the dynamics. A particular type of these transitions occurs when the size of a chaotic attractor suddenly changes. In this article, we present such a transition through the observation of a chaotic interior crisis in the Deng bursting-spiking model for the glucose-induced electrical activity of pancreatic β-cells. To this chaos-chaos transition corresponds precisely the change between the bursting and spiking dynamics, which are central and key dynamical regimes that the Deng model is able to perform...
August 1, 2017: Mathematical Biosciences and Engineering: MBE
Elena Braverman, Daniel Franco
In contrast with unstructured models, structured discrete population models have been able to fit and predict chaotic experimental data. However, most of the chaos control techniques in the literature have been designed and analyzed in a one-dimensional setting. Here, by introducing target-oriented control for discrete dynamical systems, we prove the possibility to stabilize a chosen state for a wide range of structured population models. The results are illustrated with introducing a control in the celebrated LPA model describing a flour beetle dynamics...
June 12, 2017: Bulletin of Mathematical Biology
Zhenci Xu, Ying Tang, Thomas Connor, Dapeng Li, Yunkai Li, Jianguo Liu
Climate variability and trends have significant environmental and socioeconomic impacts. Global challenges such as food security, biodiversity loss, water scarcity and human health are affected by reference evapotranspiration, temperature, solar radiation, and precipitation together, but nonlinear dynamics of these four climatic factors have not been assessed simultaneously at the national scale. This leads to unclear climatic dynamics and limited applications. To address this knowledge gap, we analyzed the daily variability and trends of four climatic factors (reference evapotranspiration, temperature, solar radiation, and precipitation) in China simultaneously using high spatial resolution data from 1960 to 2013...
June 12, 2017: Scientific Reports
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