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Nonlinear dynamics

Réka Albert, Biswa R Acharya, Byeong Wook Jeon, Jorge G T Zañudo, Mengmeng Zhu, Karim Osman, Sarah M Assmann
Stomata, microscopic pores in leaf surfaces through which water loss and carbon dioxide uptake occur, are closed in response to drought by the phytohormone abscisic acid (ABA). This process is vital for drought tolerance and has been the topic of extensive experimental investigation in the last decades. Although a core signaling chain has been elucidated consisting of ABA binding to receptors, which alleviates negative regulation by protein phosphatases 2C (PP2Cs) of the protein kinase OPEN STOMATA 1 (OST1) and ultimately results in activation of anion channels, osmotic water loss, and stomatal closure, over 70 additional components have been identified, yet their relationships with each other and the core components are poorly elucidated...
September 22, 2017: PLoS Biology
Alberto Foletti, Larissa Brizhik
Biological organisms are complex open dissipative systems whose dynamical stability is sustained due to the exchange of matter, energy and information. Dynamical stability occurs through a number of mechanisms that sustain efficient adaptive dynamics. Such properties of living matter can be the consequence of a self-consistent state of matter and electromagnetic field (EMF). Based on the soliton model of charge transport in redox processes, we describe a possible mechanism of the origin of endogenous EMF and coherence...
September 22, 2017: Electromagnetic Biology and Medicine
Wei Hu, Lin Lin, Chao Yang
The commutator direct inversion of the iterative subspace (commutator DIIS or C-DIIS) method developed by Pulay is an efficient and the most widely used scheme in quantum chemistry to accelerate the convergence of self consistent field (SCF) iterations in Hartree-Fock theory and Kohn-Sham density functional theory. The C-DIIS method requires the explicit storage of the density matrix, the Fock matrix and the commutator matrix. Hence the method can only be used for systems with a relatively small basis set, such as the Gaussian basis set...
September 22, 2017: Journal of Chemical Theory and Computation
Weide Li, Demeng Kong, Jinran Wu
Air pollution in China is becoming more serious especially for the particular matter (PM) because of rapid economic growth and fast expansion of urbanization. To solve the growing environment problems, daily PM2.5 and PM10 concentration data form January 1, 2015, to August 23, 2016, in Kunming and Yuxi (two important cities in Yunnan Province, China) are used to present a new hybrid model CI-FPA-SVM to forecast air PM2.5 and PM10 concentration in this paper. The proposed model involves two parts. Firstly, due to its deficiency to assess the possible correlation between different variables, the cointegration theory is introduced to get the input-output relationship and then obtain the nonlinear dynamical system with support vector machine (SVM), in which the parameters c and g are optimized by flower pollination algorithm (FPA)...
2017: Computational Intelligence and Neuroscience
Dong Wang, Lori R Arlinghaus, Thomas E Yankeelov, Xiaoping Yang, David S Smith
PURPOSE: Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is used in cancer imaging to probe tumor vascular properties. Compressed sensing (CS) theory makes it possible to recover MR images from randomly undersampled k-space data using nonlinear recovery schemes. The purpose of this paper is to quantitatively evaluate common temporal sparsity-promoting regularizers for CS DCE-MRI of the breast. METHODS: We considered five ubiquitous temporal regularizers on 4...
2017: International Journal of Biomedical Imaging
Simon Koplev, James Longden, Jesper Ferkinghoff-Borg, Mathias Blicher Bjerregård, Thomas R Cox, Janine T Erler, Jesper T Pedersen, Franziska Voellmy, Morten O A Sommer, Rune Linding
Signaling networks are nonlinear and complex, involving a large ensemble of dynamic interaction states that fluctuate in space and time. However, therapeutic strategies, such as combination chemotherapy, rarely consider the timing of drug perturbations. If we are to advance drug discovery for complex diseases, it will be essential to develop methods capable of identifying dynamic cellular responses to clinically relevant perturbations. Here, we present a Bayesian dose-response framework and the screening of an oncological drug matrix, comprising 10,000 drug combinations in melanoma and pancreatic cancer cell lines, from which we predict sequentially effective drug combinations...
September 19, 2017: Cell Reports
Sunil Chinnadurai, Poongundran Selvaprabhu, Yongchae Jeong, Xueqin Jiang, Moon Ho Lee
In this paper, we examine the robust beamforming design to tackle the energy efficiency (EE) maximization problem in a 5G massive multiple-input multiple-output (MIMO)-non-orthogonal multiple access (NOMA) downlink system with imperfect channel state information (CSI) at the base station. A novel joint user pairing and dynamic power allocation (JUPDPA) algorithm is proposed to minimize the inter user interference and also to enhance the fairness between the users. This work assumes imperfect CSI by adding uncertainties to channel matrices with worst-case model, i...
September 18, 2017: Sensors
Jan Humplik, Gašper Tkačik
Advances in multi-unit recordings pave the way for statistical modeling of activity patterns in large neural populations. Recent studies have shown that the summed activity of all neurons strongly shapes the population response. A separate recent finding has been that neural populations also exhibit criticality, an anomalously large dynamic range for the probabilities of different population activity patterns. Motivated by these two observations, we introduce a class of probabilistic models which takes into account the prior knowledge that the neural population could be globally coupled and close to critical...
September 19, 2017: PLoS Computational Biology
Kaiqiang Feng, Jie Li, Xiaoming Zhang, Chong Shen, Yu Bi, Tao Zheng, Jun Liu
In order to reduce the computational complexity, and improve the pitch/roll estimation accuracy of the low-cost attitude heading reference system (AHRS) under conditions of magnetic-distortion, a novel linear Kalman filter, suitable for nonlinear attitude estimation, is proposed in this paper. The new algorithm is the combination of two-step geometrically-intuitive correction (TGIC) and the Kalman filter. In the proposed algorithm, the sequential two-step geometrically-intuitive correction scheme is used to make the current estimation of pitch/roll immune to magnetic distortion...
September 19, 2017: Sensors
Brady Z Foreman, Kyle M Straub
Terrestrial paleoclimate records rely on proxies hosted in alluvial strata whose beds are deposited by unsteady and nonlinear geomorphic processes. It is broadly assumed that this renders the resultant time series of terrestrial paleoclimatic variability noisy and incomplete. We evaluate this assumption using a model of oscillating climate and the precise topographic evolution of an experimental alluvial system. We find that geomorphic stochasticity can create aliasing in the time series and spurious climate signals, but these issues are eliminated when the period of climate oscillation is longer than a key time scale of internal dynamics in the geomorphic system...
September 2017: Science Advances
Sheila E Crowell, Jonathan E Butner, Travis J Wiltshire, Ascher K Munion, Mona Yaptangco, Theodore P Beauchaine
High sensitivity and reactivity to behaviors of family members characterizes several forms of psychopathology, including self-inflicted injury (SII). We examined mother-daughter behavioral and psychophysiological reactivity during a conflict discussion using nonlinear dynamics to assess asymmetrical associations within time-series data. Depressed, SII, and control adolescents and their mothers participated (n=76 dyads). We expected that (1) mothers' evocative behaviors would affect behavioral and psychophysiological reactivity among depressed and, especially, SII adolescents, (2) adolescents' behaviors would not evoke mothers' behavioral or physiological reactivity, and (3) control teens and mothers would be less reactive, with no dynamic associations in either direction...
March 1, 2017: Clinical Psychological Science
Tahra L Eissa, Koen Dijkstra, Christoph Brune, Ronald G Emerson, Michel J A M van Putten, Robert R Goodman, Guy M McKhann, Catherine A Schevon, Wim van Drongelen, Stephan A van Gils
Small-scale neuronal networks may impose widespread effects on large network dynamics. To unravel this relationship, we analyzed eight multiscale recordings of spontaneous seizures from four patients with epilepsy. During seizures, multiunit spike activity organizes into a submillimeter-sized wavefront, and this activity correlates significantly with low-frequency rhythms from electrocorticographic recordings across a 10-cm-sized neocortical network. Notably, this correlation effect is specific to the ictal wavefront and is absent interictally or from action potential activity outside the wavefront territory...
September 18, 2017: Proceedings of the National Academy of Sciences of the United States of America
Seyed Alireza Derakhshanrad, Emily Piven, Bahareh Zeynalzadeh Ghoochani
Walter J. Freeman pioneered the neurodynamic model of brain activity when he described the brain dynamics for cognitive information transfer as the process of circular causality at intention, meaning, and perception (IMP) levels. This view contributed substantially to establishment of the Intention, Meaning, and Perception Model of Neuro-occupation in occupational therapy. As described by the model, IMP levels are three components of the brain dynamics system, with nonlinear connections that enable cognitive function to be processed in a circular causality fashion, known as Cognitive Process of Circular Causality (CPCC)...
October 2017: Nonlinear Dynamics, Psychology, and Life Sciences
Julius Kuhl, Olga Mitina, Sander L Koole
According to the extended trust hypothesis, the ability to cope with negative experiences is grounded in intuitive positive feelings about one's existence (Kuhl, Quirin, & Koole, 2015). In the present study, the authors empirically tested this hypothesis by examining the nonlinear dynamics in a series of day-to-day autoregressive functions of affective states taken from a 30-day daily mood diary study among 40 participants. A parameter (?) related to the asymptotic level of day-to-day changes in implicit positive mood predicted action orientation, a personality variable that relates to coping with negative affect, and psychological symptoms...
October 2017: Nonlinear Dynamics, Psychology, and Life Sciences
William H Sulis
Walter Freeman III pioneered the application of nonlinear dynamical systems theories and methodologies in his work on mesoscopic brain dynamics.Sadly, mainstream psychology and psychiatry still cling to linear correlation based data analysis techniques, which threaten to subvert the process of experimentation and theory building. In order to progress, it is necessary to develop tools capable of managing the stochastic complexity of complex biopsychosocial systems, which includes multilevel feedback relationships, nonlinear interactions, chaotic dynamics and adaptability...
October 2017: Nonlinear Dynamics, Psychology, and Life Sciences
Yuri I Alexandrov, Andrei K Krylov, Karina R Arutyunova
Walter Freeman's work emphasises the role of individual activity and intentionality as opposed to the traditional stimulus-reaction view and the machine metaphor. The results of our computer modeling studies suggest the nonlinear dynamics of experience emerging from perception-action cycles. We consider the perception-action cycle as a behavioral continuum of anticipated outcomes of actions. Neuroscientific research shows that each behavioral act is based on the activity of behaviorally specialized neurons distributed across the brain...
October 2017: Nonlinear Dynamics, Psychology, and Life Sciences
Xuemei He, Pengyun Yu, Juan Zhao, Jianping Wang
Ultrafast vibrational relaxation and structural dynamics of indigo carmine in dimethylsulfoxide were examined using femtosecond pump-probe infrared and two-dimensional infrared (2D IR) spectroscopies. Using the intramolecularly hydrogen-bonded C=O and delocalized C=C stretching modes as infrared probes, local structural and dynamical variations of this blue dye molecule were observed. Energy relaxation of vibrationally excited C=O stretching mode was found to occur through covalent bond to the delocalized aromatic vibrational modes on the time scale of a few picoseconds or less...
September 18, 2017: Journal of Physical Chemistry. B
Mudassar Iqbal, Neil Doherty, Anna M L Page, Saara N A Qazi, Ishan Ajmera, Peter A Lund, Theodore Kypraios, David J Scott, Philip J Hill, Dov J Stekel
The bacterial Lux system is used as a gene expression reporter. It is fast, sensitive and non-destructive, enabling high frequency measurements. Originally developed for bacterial cells, it has also been adapted for eukaryotic cells, and can be used for whole cell biosensors, or in real time with live animals without the need for euthanasia. However, correct interpretation of bioluminescent data is limited: the bioluminescence is different from gene expression because of nonlinear molecular and enzyme dynamics of the Lux system...
September 18, 2017: PLoS Computational Biology
Martijn P Vlaar, Georgios Birpoutsoukis, John Lataire, Maarten Schoukens, Alfred C Schouten, Johan Schoukens, Frans C T van der Helm
Joint manipulation elicits a response from the sensors in the periphery which, via the spinal cord, arrives in the cortex. The average evoked cortical response recorded using electroencephalography was shown to be highly nonlinear; a linear model can only explain 10% of the variance of the evoked response, and over 80% of the response is generated by nonlinear behavior. The goal of this study is to obtain a nonparametric nonlinear dynamic model, which can consistently explain the recorded cortical response requiring little a priori assumptions about model structure...
September 13, 2017: IEEE Transactions on Neural Systems and Rehabilitation Engineering
Guangliang Hu, Gaind P Pandey, Qingfeng Liu, Radhika S Anaredy, Chunrui Ma, Ming Liu, Jun Li, Scott K Shaw, Judy Z Wu
Electrochemical effects manifest as nonlinear responses to an applied electric field in electrochemical devices, and are linked intimately to the molecular orientation of ions in the electric double layer (EDL). Herein, we probe the origin of the electrochemical effect using a double-gate graphene field effect transistor (GFET) of ionic liquid N,N-diethyl-N-(2-methoxyethyl)-N-methylammonium bis-(trifluoromethylsulfonyl)-imide (DEME-TFSI) top-gate, paired with a ferroelectric Pb0.92La0.08Zr0.52Ti0.48O3 (PLZT) back-gate of compatible gating efficiency...
September 18, 2017: ACS Applied Materials & Interfaces
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