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Alba Nicolas-Boluda, Amanda K A Silva, Sylvie Fournel, Florence Gazeau
Physical oncology is an emerging paradigm which recognizes tissue mechanics, per se, as an active modulator of tumorigenesis, treatment resistance and clinical outcome, mediated by mechanosignaling pathways, matrix remodeling and physical barriers to drugs. The tumor microenvironment displays abnormal physical properties in comparison to healthy tissue which contribute to cancer progression and resistance to current treatments. Physical aberrancies comprise the chaotic organization of tumor vasculature, an increased interstitial pressure, an increased solid stress, hypoxia, an abundant extracellular matrix and a progressive stiffening of solid tumors...
October 6, 2017: Biomaterials
Yanping Xu, Mingjiang Zhang, Liang Zhang, Ping Lu, Stephen Mihailov, Xiaoyi Bao
We demonstrate that a semiconductor laser perturbed by distributed feedback with random time delays from a large number of scattering centers along a fiber random grating can emit light chaotically without the time-delay signature (TDS). A theoretical model is developed based on the modified Lang-Kobayashi model to numerically explore the chaotic dynamics of the laser diode subjected to random feedback. It is predicted that the random distributed feedback destroys the phase-correlated mode condition and hence suppresses the TDS...
October 15, 2017: Optics Letters
Haifeng Xing, Bo Hou, Zhihui Lin, Meifeng Guo
MEMS (Micro Electro Mechanical System) gyroscopes have been widely applied to various fields, but MEMS gyroscope random drift has nonlinear and non-stationary characteristics. It has attracted much attention to model and compensate the random drift because it can improve the precision of inertial devices. This paper has proposed to use wavelet filtering to reduce noise in the original data of MEMS gyroscopes, then reconstruct the random drift data with PSR (phase space reconstruction), and establish the model for the reconstructed data by LSSVM (least squares support vector machine), of which the parameters were optimized using CPSO (chaotic particle swarm optimization)...
October 13, 2017: Sensors
Kenneth V Iserson
BACKGROUND: Emergency medicine personnel frequently respond to major disasters. They expect to have an effective and efficient management system to elegantly allocate available resources. Despite claims to the contrary, experience demonstrates this rarely occurs. OBJECTIVES: This article describes privatizing disaster assessment using a single-purposed, accountable, and well-trained organization. The goal is to achieve elegant disaster assessment, rather than repeatedly exhorting existing groups to do it...
September 2017: Journal of Emergency Medicine
Justine Bresson, Stefan Bieker, Lena Riester, Jasmin Doll, Ulrike Zentgraf
Leaf senescence is not a chaotic breakdown but a dynamic process following a precise timetable. It enables plants to economize with their resources and control their own viability and integrity. The onset as well as the progression of leaf senescence are co-ordinated by a complex genetic network that continuously integrates developmental and environmental signals such as biotic and abiotic stresses. Therefore, studying senescence requires an integrative and multi-scale analysis of the dynamic changes occurring in plant physiology and metabolism...
August 1, 2017: Journal of Experimental Botany
Allan R Willms, Petko M Kitanov, William F Langford
In 1665, Huygens observed that two identical pendulum clocks, weakly coupled through a heavy beam, soon synchronized with the same period and amplitude but with the two pendula swinging in opposite directions. This behaviour is now called anti-phase synchronization. This paper presents an analysis of the behaviour of a large class of coupled identical oscillators, including Huygens' clocks, using methods of equivariant bifurcation theory. The equivariant normal form for such systems is developed and the possible solutions are characterized...
September 2017: Royal Society Open Science
C J Cotter, G A Gottwald, D D Holm
In Holm (Holm 2015 Proc. R. Soc. A471, 20140963. (doi:10.1098/rspa.2014.0963)), stochastic fluid equations were derived by employing a variational principle with an assumed stochastic Lagrangian particle dynamics. Here we show that the same stochastic Lagrangian dynamics naturally arises in a multi-scale decomposition of the deterministic Lagrangian flow map into a slow large-scale mean and a rapidly fluctuating small-scale map. We employ homogenization theory to derive effective slow stochastic particle dynamics for the resolved mean part, thereby obtaining stochastic fluid partial equations in the Eulerian formulation...
September 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Stephen Jeffress, Peter Düben, Tim Palmer
Motivated by the increasing energy consumption of supercomputing for weather and climate simulations, we introduce a framework for investigating the bit-level information efficiency of chaotic models. In comparison with previous explorations of inexactness in climate modelling, the proposed and tested information metric has three specific advantages: (i) it requires only a single high-precision time series; (ii) information does not grow indefinitely for decreasing time step; and (iii) information is more sensitive to the dynamics and uncertainties of the model rather than to the implementation details...
September 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
Shamsul Islam, Ghazala Nazeer, Zhou Chao Ying, Ziaul Islam, Raheela Manzoor
A two-dimensional numerical study of flow across rows of identical square cylinders arranged in staggered fashion is carried out. This study will unreveal complex flow physics depending upon the Reynolds number (Re) and gap spacing (g) between the cylinders. The combined effect of Reynolds number and gap spacing on the flow physics around staggered rows of cylinders are numerically studied for 20 ≤ Re ≤ 140 and 1 ≤ g ≤ 6. We use the lattice Boltzmann method for numerical computations. It is found that with increase in gap spacing between the cylinders the critical Reynolds number for the onset of vortex shedding also increases...
2017: PloS One
A Rosten, T Newton
Eating disorders are a potentially life-threatening group of mental disorders, which affect a patient's relationship with food and their body. This manifests itself through chaotic and disordered eating habits. One such eating disorder is bulimia nervosa, which has a lifetime prevalence of 1%. While there is consensus that bulimic behaviour directly causes dental erosion due to vomiting and acidic food choices, there is less clear evidence for a direct link between bulimia nervosa and dental caries, although there does still appear to be an association...
November 2017: British Dental Journal
Michael Harney, Julie Seal
Tumorigenesis can be modeled as a system of chaotic, nonlinear differential equations. From the analysis of these equations in state space, a feedback compensator is designed to stabilize the system based on a desired response. The feedback array constants represent four transducer molecules which could be used for any tumor type that obeys the same dynamics as the model, reducing drug investment requirements for a wider range of cancer treatment.
2017: Advances in Experimental Medicine and Biology
A A Ali, A Haidar, O Polonskyi, F Faupel, H Abdul-Khaliq, M Veith, O C Aktas
The tuning of wetting over an extreme range, from superhydrophilic to superhydrophobic, was demonstrated on 1D Al/Al2O3 nanostructures. While chaotic and tangled 1D Al/Al2O3 nanostructures exhibited complete wetting, they became water repellent (with a water contact angle (CA) ≥173°) after the infiltration of poly[bis(2,2,2-trifluoroethoxy)phosphazene] (PTFEP) solution. This simple strategy allows the achievement of two extreme wetting regimes, perfect wetting and non-wetting, without altering the nanostructured surface topography...
October 12, 2017: Nanoscale
Barry K Carpenter, Gregory S Ezra, Stavros C Farantos, Zeb C Kramer, Stephen Wiggins
Classical Hamiltonian trajectories are initiated at random points in phase space on a fixed energy shell of a model two degree of freedom potential, consisting of two interacting minima in an otherwise flat energy plane of infinite extent. Below the energy of the plane, the dynamics are demonstrably chaotic. However, most of the work in this paper involves trajectories at a fixed energy that is 1% above that of the plane, in which regime the dynamics exhibit behavior characteristic of chaotic scattering. The trajectories are analyzed without reference to the potential, as if they had been generated in a typical direct molecular dynamics simulation...
October 2, 2017: Journal of Physical Chemistry. B
A Collet, J Bragard, P C Dauby
This article characterizes the cardiac autonomous electrical activity induced by the mechanical deformations in the cardiac tissue through the mechano-electric feedback. A simplified and qualitative model is used to describe the system and we also account for temperature effects. The analysis emphasizes a very rich dynamics for the system, with periodic solutions, alternans, chaotic behaviors, etc. The possibility of self-sustained oscillations is analyzed in detail, particularly in terms of the values of important parameters such as the dimension of the system and the importance of the stretch-activated currents...
September 2017: Chaos
Philip Bittihn, Sebastian Berg, Ulrich Parlitz, Stefan Luther
Self-organized activation patterns in excitable media such as spiral waves and spatio-temporal chaos underlie dangerous cardiac arrhythmias. While the interaction of single spiral waves with different types of heterogeneity has been studied extensively, the effect of heterogeneity on fully developed spatio-temporal chaos remains poorly understood. We investigate how the complexity and stability properties of spatio-temporal chaos in the Bär-Eiswirth model of excitable media depend on the heterogeneity of the underlying medium...
September 2017: Chaos
Shahriar Iravanian, Jonathan J Langberg
Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia with significant morbidity and mortality. Pharmacological agents are not very effective in the management of AF. Therefore, ablation procedures have become the mainstay of AF management. The irregular and seemingly chaotic atrial activity in AF is caused by one or more meandering spiral waves. Previously, we have shown the presence of sudden rhythm organization during ablation of persistent AF. We hypothesize that the observed transitions from a disorganized to an organized rhythm is a critical phase transition...
September 2017: Chaos
Christopher D Marcotte, Roman O Grigoriev
While spiral wave breakup has been implicated in the emergence of atrial fibrillation, its role in maintaining this complex type of cardiac arrhythmia is less clear. We used the Karma model of cardiac excitation to investigate the dynamical mechanisms that sustain atrial fibrillation once it has been established. The results of our numerical study show that spatiotemporally chaotic dynamics in this regime can be described as a dynamical equilibrium between topologically distinct types of transitions that increase or decrease the number of wavelets, in general agreement with the multiple wavelets' hypothesis...
September 2017: Chaos
M G Clerc, M A Ferré, S Coulibaly, R G Rojas, M Tlidi
We consider coupled-waveguide resonators subject to optical injection. The dynamics of this simple device are described by the discrete Lugiato-Lefever equation. We show that chimera-like states can be stabilized, thanks to the discrete nature of the coupled-waveguide resonators. Such chaotic localized structures are unstable in the continuous Lugiato-Lefever model; this is because of dispersive radiation from the tails of localized structures in the form of two counter-propagating fronts between the homogeneous and the complex spatiotemporal state...
August 1, 2017: Optics Letters
Anton Turygin, Denis Alikin, Yury Alikin, Vladimir Shur
We have studied experimentally the interaction of isolated needle-like domains created in an array via local switching using a biased scanning probe microscope (SPM) tip and visualized via piezoelectric force microscopy (PFM) at the non-polar cuts of MgO-doped lithium niobate (MgOLN) crystals. It has been found that the domain interaction leads to the intermittent quasiperiodic and chaotic behavior of the domain length in the array in a manner similar to that of polar cuts, but with greater spacing between the points of bias application and voltage amplitudes...
September 28, 2017: Materials
Seshadri Sivakumar, Shyamala Sivakumar
This paper introduces a discrete-time recurrent neural network architecture using triangular feedback weight matrices that allows a simplified approach to ensuring network and training stability. The triangular structure of the weight matrices is exploited to readily ensure that the eigenvalues of the feedback weight matrix represented by the block diagonal elements lie on the unit circle in the complex z-plane by updating these weights based on the differential of the angular error variable. Such placement of the eigenvalues together with the extended close interaction between state variables facilitated by the nondiagonal triangular elements, enhances the learning ability of the proposed architecture...
September 25, 2017: IEEE Transactions on Cybernetics
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