scholarly journals ROLE OF THE COLORED NOISE IN SPATIO-TEMPORAL BEHAVIOR OF TWO COMPETING SPECIES

2005 ◽  
Vol 05 (02) ◽  
pp. L337-L342 ◽  
Author(s):  
D. VALENTI ◽  
A. FIASCONARO ◽  
B. SPAGNOLO
Keyword(s):  
Noise Intensity ◽  
Large Scale ◽  
Colored Noise ◽  
Spatial Distributions ◽  
Temporal Behavior ◽  
Spatial Correlations ◽  
Interacting Species ◽  
Spatio Temporal ◽  
Nonmonotonic Behavior

We study the spatial distributions of two randomly interacting species, in the presence of an external multiplicative colored noise. The dynamics of the ecosystem is described by a coupled map lattice model. We find a nonmonotonic behavior in the formation of large scale spatial correlations as a function of the multiplicative colored noise intensity. This behavior is shifted towards higher values of the noise intensity for increasing correlation time of the noise.

scholarly journals NONMONOTONIC PATTERN FORMATION IN THREE SPECIES LOTKA–VOLTERRA SYSTEM WITH COLORED NOISE

2005 ◽  
Vol 05 (02) ◽  
pp. L305-L311 ◽  
Author(s):  
A. FIASCONARO ◽  
D. VALENTI ◽  
B. SPAGNOLO
Keyword(s):  
Pattern Formation ◽  
Noise Intensity ◽  
Colored Noise ◽  
Multiplicative Noise ◽  
Volterra Equations ◽  
Volterra System ◽  
Spatiotemporal Evolution ◽  
Species Concentration ◽  
Interacting Species ◽  
Nonmonotonic Behavior

A coupled map lattice of generalized Lotka–Volterra equations in the presence of colored multiplicative noise is used to analyze the spatiotemporal evolution of three interacting species: one predator and two preys symmetrically competing each other. The correlation of the species concentration over the grid as a function of time and of the noise intensity is investigated. The presence of noise induces pattern formation, whose dimensions show a nonmonotonic behavior as a function of the noise intensity. The colored noise induces a greater dimension of the patterns with respect to the white noise case and a shift of the maximum of its area towards higher values of the noise intensity.

scholarly journals Why a Large-Scale Mode Can Be Essential for Understanding Intracellular Actin Waves

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1533 ◽  
Author(s):  
Carsten Beta ◽  
Nir S. Gov ◽  
Arik Yochelis
Keyword(s):  
Large Scale ◽  
Mass Conservation ◽  
Coarse Grained ◽  
Cellular Functions ◽  
Multi Scale ◽  
Spatio Temporal ◽  
Actin Waves ◽  
Inhibitor Type ◽  
Activator Inhibitor Type

During the last decade, intracellular actin waves have attracted much attention due to their essential role in various cellular functions, ranging from motility to cytokinesis. Experimental methods have advanced significantly and can capture the dynamics of actin waves over a large range of spatio-temporal scales. However, the corresponding coarse-grained theory mostly avoids the full complexity of this multi-scale phenomenon. In this perspective, we focus on a minimal continuum model of activator–inhibitor type and highlight the qualitative role of mass conservation, which is typically overlooked. Specifically, our interest is to connect between the mathematical mechanisms of pattern formation in the presence of a large-scale mode, due to mass conservation, and distinct behaviors of actin waves.

Non-Linear Mechanisms in the Brain

1998 ◽  
Vol 53 (7-8) ◽  
pp. 677-685 ◽  
Author(s):  
Gottfried Mayer-Kress
Keyword(s):  
Large Scale ◽  
Brain Activity ◽  
External Noise ◽  
Neuronal System ◽  
Neuron Models ◽  
General Role ◽  
Non Linear ◽  
Spatio Temporal ◽  
The Brain

Abstract Non-linear dynamical models of brain activity can describe the spontaneous emergence of large-scale coherent structures both in a temporal and spatial domain. We discuss a number of discrete time dynamical neuron models that illustrate some of the mechanisms involved. Of special interest is the phenomenon of spatio-temporal stochastic resonance in which co­herent structures emerge as a result of the interaction of the neuronal system with external noise at a given level punitive data. We then discuss the general role of stochastic noise in brain dynamics and how similar concepts can be studied in the context of networks of con­nected brains on the Internet.

scholarly journals Role of Convective Entrainment in Spatial Distributions of and Temporal Variations in Precipitation over Tropical Oceans

2014 ◽  
Vol 27 (23) ◽  
pp. 8707-8723 ◽  
Author(s):  
Nagio Hirota ◽  
Yukari N. Takayabu ◽  
Masahiro Watanabe ◽  
Masahide Kimoto ◽  
Minoru Chikira
Keyword(s):  
Large Scale ◽  
Lower Troposphere ◽  
Temporal Variations ◽  
Spatial And Temporal Variations ◽  
Spatial Distributions ◽  
Atmospheric Models ◽  
Tropical Oceans ◽  
Appropriate Treatment ◽  
Precipitation Events

Abstract The authors demonstrate that an appropriate treatment of convective entrainment is essential for determining spatial distributions of and temporal variations in precipitation. Four numerical experiments are performed using atmospheric models with different entrainment characteristics: a control experiment (Ctl), a no-entrainment experiment (NoEnt), an original Arakawa–Schubert experiment (AS), and an AS experiment with a simple empirical suppression of convection depending on cloud-layer humidity (ASRH). The fractional entrainment rates of AS and ASRH are constant for each cloud type and are very small in the lower troposphere compared with those in the Ctl, in which half of the buoyancy-generated energy is consumed by entrainment. Spatial and temporal variations in the observed precipitation are satisfactorily reproduced in the Ctl, but their amplitudes are underestimated with a so-called double intertropical convergence zone bias in the NoEnt and AS. The spatial variation is larger in the Ctl because convection is more active over humid ascending regions and more suppressed over dry subsidence regions. Feedback processes involving convection, the large-scale circulation, free tropospheric moistening by congestus, and radiation enhance the variations. The temporal evolution of precipitation events is also more realistic in the Ctl, because congestus moistens the midtroposphere, and large precipitation events occur once sufficient moisture is available. The large entrainment in the lower troposphere, increasing free tropospheric moistening by congestus and enhancing the coupling of convection to free tropospheric humidity, is suggested to be important for the realistic spatial and temporal variations.

Dynamics of arc-continent collision: the role of crustal-mantle dynamics on controlling the spatio-temporal evolution of stress 

2021 ◽  
Author(s):  
Andres Felipe Rodriguez Corcho ◽  
Sara Morón ◽  
Rebecca Farrington ◽  
Romain Beucher ◽  
Louis Moresi ◽  
...  
Keyword(s):  
Lithospheric Mantle ◽  
Large Scale ◽  
Temporal Evolution ◽  
Density Contrast ◽  
Simultaneous Occurrence ◽  
Return Flow ◽  
Continental Lithosphere ◽  
Mantle Dynamics ◽  
Spatio Temporal

<p>Arc-continent collision is the process by which intra-oceanic arc crust is accreted to continental margins and the most important mechanism that enables the growth of the continental crust since Phanerozoic times. We use numerical visco-plastic mechanical models to explore: (i) the role of lithospheric-mantle dynamics in controlling the spatio-temporal evolution of stress in arc-continent collision settings, and (ii) the role of density contrasts in the evolution of the stress regime. We performed a series of simulations only varying the thickness of the arc based on natural examples as the arc thickness controls the buoyancy of intra-oceanic arcs. Therefore, we investigated a range of density contrasts between the arc and the continental plate. Modelling results show that arc-continent collision can evolve into two contrasting scenarios: (i) slab-anchoring and arc transference in dense arcs where the density contrast between the arc and the adjacent continental lithosphere is above -3% (15-31 km in thickness); and (ii) slab break-off in buoyant arcs where the density contrast between the arc and the adjacent continental lithosphere is below -3% (32-35 km in thickness). We conclude that the large-scale mantle return flow emerged from slab-anchoring facilitates the simultaneous occurrence of compression and extension in the margin by enhancing: (i) compression and lithospheric thickening of the buoyant intra-oceanic arc crust; and (ii) the density contrast between the accreted arc and the continental margin that triggers the release of a gravitational flow. In the particular case of buoyant arcs, the compressional body force applied by the deformed arc to the subducting plate drives its passive retreat. The results of our numerical modelling highlight the importance of the role of lithospheric-mantle dynamics on controlling the spatio-temporal evolution of stress.</p>

scholarly journals Distribution and evolution of quasars

1999 ◽  
Vol 183 ◽  
pp. 259-259
Author(s):  
S. Nasiri ◽  
V. Rezania
Keyword(s):  
Angular Momentum ◽  
Large Scale ◽  
Number Density ◽  
Spatial Correlations ◽  
Normal Galaxies ◽  
Evolution Of Galaxies ◽  
Dust Clouds ◽  
Large Scale Universe ◽  
Fast Rotating

In this paper we investigate: a) The evolution of quasars on the basis of gravitational contraction model of proto-galaxies. This is done by studying the number density of quasars given by Veron catalogue [1] in different luminosity classes. The order of classes increase with increasing the luminosity of corresponding quasars. It is shown that the decay of quasars is more sensible to their luminosities as expected by assuming that they are evolved from the contraction of slowly rotating proto-galaxies. The role of the angular momentum in the evolution of galaxies is emphasized by the results obtained from the size-luminosity relation of about 40,000 normal galaxies given by LEDA database [2]. In the model mentioned above the normal galaxies are assumed to be evolved from the contraction of relatively fast rotating proto-galaxies. b) The filamentary structures and voids of the large scale universe by plotting the entire sky map of quasars in the galactic coordinate. This is done by assuming that these objects are at cosmological distances. The result which is plotted in the following figure, seems to show some spatial correlations of quasars distribution. The region of missing quasars is due to the dust clouds in our galaxy which block our view of other quasars. Note the voids and clumpy distribution of quasars looking like filaments.

Diagnosing Evolution of Cloud Cluster via Spatio-temporal Trace Analysis

2021 ◽  
Author(s):  
Li Ruan ◽  
Yunpeng Jiao ◽  
Tingyu Lin ◽  
Limin Xiao ◽  
Nasro Min-Allah ◽  
...  
Keyword(s):  
Trace Analysis ◽  
Large Scale ◽  
Cloud Data Center ◽  
Workload Analysis ◽  
Cloud Data ◽  
Cloud Cluster ◽  
New Findings ◽  
Spatio Temporal

To analyze inner-enterprise cloud cluster performance, the role of workload analysis is of paramount interest to system designers. However, the ever-evolving nature of inner-enterprise cloud platforms such as diversity and spatio-temporal nature of workloads makes evolution diagnosing a challenging task. In this paper, we propose MuCoTrAna-Inner, an evolution diagnosing approach for a large-scale cloud data center based on comparative spatio-temporal trace analysis. Moreover, we present a case study on two representative big traces: Alibaba 2017 trace, and Alibaba 2018 trace. Novel quantitative findings along with the performance bottleneck inferences and recommendations based on workload analysis are provided. Our multifaceted analyses of the traces and new findings not only reveal interesting insights that are of interest to system designers and administrators, but also establish a new view to diagnosing the evolution of inner-enterprise cloud cluster based on trace analysis.

scholarly journals Lagrangian betweenness as a measure of bottlenecks in dynamical systems with oceanographic examples

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Enrico Ser-Giacomi ◽  
Alberto Baudena ◽  
Vincent Rossi ◽  
Mick Follows ◽  
Sophie Clayton ◽  
...  
Keyword(s):  
Dynamical Systems ◽  
Network Theory ◽  
Fluid Transport ◽  
Oceanic Circulation ◽  
Spatial Correlations ◽  
Effective Measure ◽  
The Pacific ◽  
The Pacific Ocean ◽  
Spatio Temporal

AbstractThe study of connectivity patterns in networks has brought novel insights across diverse fields ranging from neurosciences to epidemic spreading or climate. In this context, betweenness centrality has demonstrated to be a very effective measure to identify nodes that act as focus of congestion, or bottlenecks, in the network. However, there is not a way to define betweenness outside the network framework. By analytically linking dynamical systems and network theory, we provide a trajectory-based formulation of betweenness, called Lagrangian betweenness, as a function of Lyapunov exponents. This extends the concept of betweenness beyond the context of network theory relating hyperbolic points and heteroclinic connections in any dynamical system to the structural bottlenecks of the network associated with it. Using modeled and observational velocity fields, we show that such bottlenecks are present and surprisingly persistent in the oceanic circulation across different spatio-temporal scales and we illustrate the role of these areas in driving fluid transport over vast oceanic regions. Analyzing plankton abundance data from the Kuroshio region of the Pacific Ocean, we find significant spatial correlations between measures of diversity and betweenness, suggesting promise for ecological applications.

The Role of Sense of Direction and Other Factors During Navigation in a Large-Scale, Unconstrained Environment

2013 ◽  
Author(s):  
Elisabeth J. Ploran ◽  
Ericka Rovira ◽  
James C. Thompson ◽  
Raja Parasuraman
Keyword(s):  
Large Scale ◽  
Sense Of Direction
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