Spatial Heterogeneity Induced Antispiral Wave and Spatiotemporal Coherence Resonance

2013 ◽  
Vol 647 ◽  
pp. 843-847
Author(s):  
Li Qiang Lv ◽  
Lin Ji
Keyword(s):  
Spatial Heterogeneity ◽  
Dynamic Behavior ◽  
Spiral Wave ◽  
Resonance Phenomenon ◽  
Microemulsion System ◽  
Coherence Resonance ◽  
Quantitative Characterization ◽  
Cardiac Fibrillation ◽  
Spatial Noise ◽  
Spatiotemporal Noise

Spiral wave is an important dynamic behavior in several physiological signaling processes, such as the cardiac fibrillation. Since antispiral wave recently been discovered in microemulsion system, it has been intensively studied and discussed. In this work, we find that the spatial noise induced heterogeneity in homogenous system may also induce antispiral formation. Quantitative characterization prove spatiotemporal coherence resonance phenomenon appears, and spatiotemporal noise is more favorable to optimally sustain the antispirals.

Quantitative characterization of laser ultrasonic based on energy loss and resonance phenomenon

Optik ◽  
2020 ◽  
Vol 223 ◽  
pp. 165380
Author(s):  
Feng Qin ◽  
Bing Li ◽  
Lei Chen ◽  
Tao Tang ◽  
Xiang Wei ◽  
...  
Keyword(s):  
Energy Loss ◽  
Resonance Phenomenon ◽  
Laser Ultrasonic ◽  
Quantitative Characterization

Temporal Integration and the Masking Effect of Spatiotemporal Noise

Perception ◽  
1997 ◽  
Vol 26 (1_suppl) ◽  
pp. 216-216 ◽  
Author(s):  
H T Kukkonen ◽  
J Rovamo
Keyword(s):  
Spectral Density ◽  
Exposure Duration ◽  
Temporal Integration ◽  
Detection Threshold ◽  
Critical Duration ◽  
Masking Effect ◽  
Integration Time ◽  
Detection Thresholds ◽  
Spatial Noise ◽  
Spatiotemporal Noise

In computer-generated spatiotemporal noise every stimulus frame contains a new static noise sample. The spectral density of white spatiotemporal noise is calculated by multiplying the squared rms contrast of noise by the product of the noise check area and the exposure duration of each noise check. When the exposure duration of each noise check is gradually increased, the spectral density of spatiotemporal noise increases, reaching its maximum when noise becomes static. In static spatial noise both stimulus and noise checks have the same duration. The signal-to-noise ratio is known to be constant at detection threshold. Detection thresholds should thus increase in proportion to the spectral density of spatiotemporal noise, which increases with the duration of the noise checks. We measured detection thresholds for stationary cosine gratings embedded in spatiotemporal noise. The exposure duration of the noise checks was increased from one frame duration to the total exposure duration of the stimulus grating. Noise was thus gradually transformed from spatiotemporal to static spatial noise. The contrast energy threshold increased in proportion to the spectral density of spatiotemporal noise up to a noise check duration found to be equal to the integration time for the stimulus grating without noise. After this, energy thresholds remained constant in spite of the increase in the spectral density of spatiotemporal noise. This suggests that the masking effect of spatiotemporal noise increases with the duration of noise checks up to the critical duration marking the saturation of the temporal integration of the signal.

Influence of Structural Irregularities of Tserkov Building on its Dynamic Behavior under Induced Seismic Shock of Mining Origin

2016 ◽  
Vol 703 ◽  
pp. 365-370 ◽  
Author(s):  
Joanna M. Dulinska ◽  
Katarzyna Nowakowska
Keyword(s):  
Dynamic Response ◽  
Dynamic Behavior ◽  
Resonance Phenomenon ◽  
Low Frequencies ◽  
Concrete Walls ◽  
Floor Slab ◽  
Natural Modes ◽  
Modes Of Vibration ◽  
Roof Area ◽  
Structural Irregularities

In the paper the influence of structural irregularities of a building on its dynamic behavior under a mining tremor was examined. A building of tserkov was taken into consideration as an example of irregular building. The geometry and the material properties of the tserkov resulted in irregularities of the stiffness of structure: the massive concrete walls were much more stiffer than the floor slab and the structural columns. It turned out that the irregularities of structural stiffness strongly influenced the dynamic behaviour of the object. The stiff concrete walls repeated the ground motion and moved like a rigid body. The dynamic response of the softer parts of structure, i.e. the floor slab and the concrete columns, reflected the natural modes of vibration connected with low frequencies rather than the ground movements. The higher frequencies occurring in the kinematic excitation were filtered out. To evaluate the influence of the roofing on the dynamic characteristics of the structure two variants of a numerical model were analysed: a model of the building with and without roofing. It occurred that in case of an irregular building with large roof area the inclusion of non-structural roofing elements is essential and may be of crucial importance while assessing the dynamic response of structure to seismic excitation. The negligence of these elements may result in unrecognizing of the resonance phenomenon.

scholarly journals Quantitative Characterization of CD8+ T Cell Clustering and Spatial Heterogeneity in Solid Tumors

2019 ◽  
Vol 8 ◽  
Author(s):  
Chang Gong ◽  
Robert A. Anders ◽  
Qingfeng Zhu ◽  
Janis M. Taube ◽  
Benjamin Green ◽  
...  
Keyword(s):  
T Cell ◽  
Spatial Heterogeneity ◽  
Solid Tumors ◽  
Cd8 T Cell ◽  
Quantitative Characterization ◽  
Cell Clustering

Modeling spiral Ca2+ waves in single cardiac cells: role of the spatial heterogeneity created by the nucleus

1996 ◽  
Vol 271 (4) ◽  
pp. C1390-C1399 ◽  
Author(s):  
G. Dupont ◽  
J. Pontes ◽  
A. Goldbeter
Keyword(s):  
Spatial Heterogeneity ◽  
Spiral Wave ◽  
Cardiac Cells ◽  
Release Mechanism ◽  
Cardiac Cell ◽  
Contraction Coupling ◽  
Spiral Shape ◽  
Planar Wave ◽  
Oscillations And Waves

Excitation-contraction coupling in cardiomyocytes is known to rely on the Ca(2+)-induced Ca2+ release mechanism. This autoamplification process is also very apparent when voltage-clamped or Ca(2+)-overloaded myocytes exhibit fast-propagating Ca2+ waves. Although most of the fronts are planar, some adopt a spiral shape, revealing additional characteristics about the excitability and structure of the cardiac cell (P. Lipp and E. Niggli, Biophys. J. 65: 2272-2276, 1993: J. Engel, M. Fechner, A. Sowerby, S. Finch, and A. Stier, Biophys. J. 66: 1756-1762, 1994). Using a previously developed model for Ca2+ oscillations and waves (A. Goldbeter, G. Dupont, and M.J. Berridge, Proc. Natl. Acad. Sci. USA 87: 1461-1465, 1990; G. Dupont and A. Goldbeter, Biophys. J. 67: 2191-2204, 1994), we study by numerical simulations different conditions in which spiral Ca2+ waves can occur as a result of the spatial heterogeneity created by the nucleus in a system with geometry resembling that of a myocyte. A region of the cell lacking Ca2+ pools, acting as an obstacle able to break the propagation of planar waves, suffices to initiate a spiral wave; however, this region must be properly placed with respect to the pacemaker. An obstacle behaving as a barrier to diffusion is also able to create the initial bending that can lead to the spiral wave. We study how the occurrence of spiral Ca2+ waves in single cardiomyocytes is influenced by factors such as the stimulus location and the position, shape, and dimensions of the obstacle to planar wave propagation.

scholarly journals An endogenous mechanism of business cycles

2021 ◽  
Vol 8 (3-4) ◽  
pp. 127-148
Author(s):  
Dimitri Kroujiline ◽  
Maxim Gusev ◽  
Dmitry Ushanov ◽  
Sergey V. Sharov ◽  
Boris Govorkov
Keyword(s):  
Stock Market ◽  
Business Cycles ◽  
Coupled System ◽  
Resonance Phenomenon ◽  
Market Model ◽  
Market Dynamics ◽  
Real Economy ◽  
Coherence Resonance ◽  
Market Interaction ◽  
Stable Equilibria

This paper suggests that business cycles may be a manifestation of coupled real economy and stock market dynamics and describes a mechanism that can generate economic fluctuations consistent with observed business cycles. To this end, we seek to incorporate into the macroeconomic framework a dynamic stock market model based on opinion interactions (Gusev et al., 2015). We derive this model from microfoundations, provide its empirical verification, demonstrate that it contains the efficient market as a particular regime and establish a link through which macroeconomic models can be attached for the study of real economy and stock market interaction. To examine key effects, we link it with a simple macroeconomic model (Blanchard, 1981). The coupled system generates nontrivial endogenous dynamics, which exhibit deterministic and stochastic features, producing quasiperiodic fluctuations (business cycles). We also inspect this system’s behavior in the phase space. The real economy and the stock market coevolve dynamically along the path governed by a stochastically-forced dynamical system with two stable equilibria, one where the economy expands and the other where it contracts, resulting in business cycles identified as the coherence resonance phenomenon. Thus, the incorporation of stock market dynamics into the macroeconomic framework, as presented here, allows the derivation of realistic behaviors in a tractable setting.

COHERENCE RESONANCE IN A FITZHUGH–NAGUMO ELECTRONIC SYSTEM

2007 ◽  
Vol 17 (10) ◽  
pp. 3431-3436
Author(s):  
STEFANO BRUGIONI ◽  
DONG UK HWANG ◽  
RICCARDO MEUCCI ◽  
STEFANO BOCCALETTI
Keyword(s):  
Fixed Point ◽  
Time Scales ◽  
Electronic Circuit ◽  
Noise Source ◽  
Electronic System ◽  
Resonance Phenomenon ◽  
Stable Fixed Point ◽  
Coherence Resonance ◽  
Resonance Behavior ◽  
Experimental Parameters

We investigate Coherence Resonance phenomenon in an electronic circuit obeying the FitzHugh–Nagumo dynamics. The phenomenon is induced with a noise source exhibiting different nature. The resonance behavior results are significantly reinforced when experimental parameters are tuned in order to place the stable fixed point closer to the excitability threshold of spiking behavior, as well as when the time scales of the circuit are properly modified.

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