scholarly journals A new method for probing the late-time dynamics in the Lorentzian type IIB matrix model

2017 ◽  
Vol 2017 (8) ◽  
Author(s):  
Takehiro Azuma ◽  
Yuta Ito ◽  
Jun Nishimura ◽  
Asato Tsuchiya
Keyword(s):  
Matrix Model ◽  
New Method ◽  
Late Time ◽  
Time Dynamics

scholarly journals Averaging generalized scalar field cosmologies II: locally rotationally symmetric Bianchi I and flat Friedmann–Lemaître–Robertson–Walker models

2021 ◽  
Vol 81 (6) ◽  
Author(s):  
Genly Leon ◽  
Sebastián Cuéllar ◽  
Esteban González ◽  
Samuel Lepe ◽  
Claudio Michea ◽  
...  
Keyword(s):  
Scalar Field ◽  
Nonlinear Dynamical Systems ◽  
Perturbation Parameter ◽  
Time Dependent ◽  
Late Time ◽  
De Sitter ◽  
Time Dynamics ◽  
Locally Rotationally Symmetric ◽  
Bianchi I ◽  
Rotationally Symmetric

AbstractScalar field cosmologies with a generalized harmonic potential and a matter fluid with a barotropic equation of state (EoS) with barotropic index $$\gamma $$ γ for the locally rotationally symmetric (LRS) Bianchi I and flat Friedmann–Lemaître–Robertson–Walker (FLRW) metrics are investigated. Methods from the theory of averaging of nonlinear dynamical systems are used to prove that time-dependent systems and their corresponding time-averaged versions have the same late-time dynamics. Therefore, the simplest time-averaged system determines the future asymptotic behavior. Depending on the values of $$\gamma $$ γ , the late-time attractors of physical interests are flat quintessence dominated FLRW universe and Einstein-de Sitter solution. With this approach, the oscillations entering the system through the Klein–Gordon (KG) equation can be controlled and smoothed out as the Hubble parameter H – acting as time-dependent perturbation parameter – tends monotonically to zero. Numerical simulations are presented as evidence of such behavior.

scholarly journals Universal late-time dynamics in isolated one-dimensional statistical systems with topological excitations

2020 ◽  
Vol 101 (10) ◽  
Author(s):  
Alvise Bastianello ◽  
Alessio Chiocchetta ◽  
Leticia F. Cugliandolo ◽  
Andrea Gambassi
Keyword(s):  
Late Time ◽  
One Dimensional ◽  
Topological Excitations ◽  
Time Dynamics ◽  
Statistical Systems

scholarly journals Dynamics of the cerebral blood flow response to brief neural activity in human visual cortex

2019 ◽  
Vol 40 (9) ◽  
pp. 1823-1837 ◽  
Author(s):  
Jung Hwan Kim ◽  
Amanda J Taylor ◽  
Danny JJ Wang ◽  
Xiaowei Zou ◽  
David Ress
Keyword(s):  
Blood Flow ◽  
Cerebral Blood Flow ◽  
Visual Cortex ◽  
Temporal Dynamics ◽  
Oxygen Metabolism ◽  
Late Time ◽  
Neural Activation ◽  
Hemodynamic Response Function ◽  
Time Dynamics ◽  
Human Visual Cortex

The blood oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI) signal depends on an interplay of cerebral blood flow (CBF), oxygen metabolism, and cerebral blood volume. Despite wide usage of BOLD fMRI, it is not clear how these physiological components create the BOLD signal. Here, baseline CBF and its dynamics evoked by a brief stimulus (2 s) in human visual cortex were measured at 3T. We found a stereotypical CBF response: immediate increase, rising to a peak a few second after the stimulus, followed by a significant undershoot. The BOLD hemodynamic response function (HRF) was also measured in the same session. Strong correlations between HRF and CBF peak responses indicate that the flow responses evoked by neural activation in nearby gray matter drive the early HRF. Remarkably, peak CBF and HRF were also strongly modulated by baseline perfusion. The CBF undershoot was reliable and significantly correlated with the HRF undershoot. However, late-time dynamics of the HRF and CBF suggest that oxygen metabolism can also contribute to the HRF undershoot. Combined measurement of the CBF and HRF for brief neural activation is a useful tool to understand the temporal dynamics of neurovascular and neurometabolic coupling.

Effect of Stationary Particles on the Phase Separation of Binary Fluids

2001 ◽  
Vol 710 ◽  
Author(s):  
Domenico Suppa ◽  
Olga Kuksenok ◽  
Anna C. Balazs ◽  
J.M. Yeomans
Keyword(s):  
Two Dimensions ◽  
Lattice Boltzmann Model ◽  
Late Time ◽  
Binary Fluids ◽  
Final Size ◽  
Time Dynamics ◽  
Simple Theoretical Model ◽  
Boltzmann Model ◽  
Fluid Interaction ◽  
Kinetics Of

ABSTRACTPhase separating binary fluids with the addition of immobile particles, which act as osmotic force centres, were simulated using a Lattice Boltzmann model in two dimensions. In the hydrodynamic over-damped limit, where the flow is entirely driven by capillary effects, the presence of particles that are preferentially wetted by one of the fluid components significantly affects the kinetics of the growth of the fluid domains. The late time dynamics is governed by the wetting interactions and the final size of the domains can be tailored by varying the strength of the particles-fluid interaction as well as the particles concentration. These features are predicted within a simple theoretical model and are amenable of experimental checks.

scholarly journals Yang-Baxter integrable Lindblad equations

2020 ◽  
Vol 8 (3) ◽  
Author(s):  
Aleksandra A. Ziolkowska ◽  
Fabian Essler
Keyword(s):  
Bethe Ansatz ◽  
Quantum Spin ◽  
Spin Chains ◽  
Integrable Models ◽  
Late Time ◽  
Quantum Spin Chains ◽  
Operator Formalism ◽  
One Dimensional ◽  
Time Dynamics

We consider Lindblad equations for one dimensional fermionic models and quantum spin chains. By employing a (graded) super-operator formalism we identify a number of Lindblad equations than can be mapped onto non-Hermitian interacting Yang-Baxter integrable models. Employing Bethe Ansatz techniques we show that the late-time dynamics of some of these models is diffusive.

scholarly journals Late time behaviors of the expanding universe in the IIB matrix model

2012 ◽  
Vol 2012 (10) ◽  
Author(s):  
Sang-Woo Kim ◽  
Jun Nishimura ◽  
Asato Tsuchiya
Keyword(s):  
Matrix Model ◽  
Late Time ◽  
Expanding Universe

scholarly journals Time-averaging axion-like interacting scalar fields models

2021 ◽  
Vol 81 (11) ◽  
Author(s):  
Saikat Chakraborty ◽  
Esteban González ◽  
Genly Leon ◽  
Bin Wang
Keyword(s):  
Dynamical Systems ◽  
Systems Approach ◽  
Nonlinear Dynamical Systems ◽  
Scalar Fields ◽  
Time Averaging ◽  
Late Time ◽  
Dimensionless Time ◽  
Nonlinear Dynamical ◽  
Time Dynamics ◽  
Klein Gordon

AbstractIn this paper, we study a cosmological model inspired in the axionic matter with two canonical scalar fields $$\phi _1$$ ϕ 1 and $$\phi _2$$ ϕ 2 interacting through a term added to its potential. Introducing novel dynamical variables, and a dimensionless time variable, the resulting dynamical system is studied. The main difficulties arising in the standard dynamical systems approach, where expansion normalized dynamical variables are usually adopted, are due to the oscillations entering the nonlinear system through the Klein–Gordon (KG) equations. This motivates the analysis of the oscillations using methods from the theory of averaging nonlinear dynamical systems. We prove that time-dependent systems, and their corresponding time-averaged versions, have the same late-time dynamics. Then, we study the time-averaged system using standard techniques of dynamical systems. We present numerical simulations as evidence of such behavior.

scholarly journals Impact of Collisional Matter on the Late-Time Dynamics of f(R,T) Gravity

Symmetry ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 463 ◽  
Author(s):  
M. Zubair ◽  
Muhammad Zeeshan ◽  
Syed Hasan ◽  
V. Oikonomou
Keyword(s):  
Dark Matter ◽  
Cold Dark Matter ◽  
State Parameter ◽  
Gravity Models ◽  
Physical Parameters ◽  
Late Time ◽  
Time Behavior ◽  
Effective Equation ◽  
Time Dynamics ◽  
Cosmic Evolution

We study the cosmic evolution of non-minimally coupled f ( R , T ) gravity in the presence of matter fluids consisting of collisional self-interacting dark matter and radiation. We study the cosmic evolution in the presence of collisional matter, and we compare the results with those corresponding to non-collisional matter and the Λ -cold-dark-matter ( Λ CDM) model. Particularly, for a flat Friedmann–Lema i ^ tre–Robertson–Walker Universe, we study two non-minimally coupled f ( R , T ) gravity models and we focus our study on the late-time dynamical evolution of the model. Our study is focused on the late-time behavior of the effective equation of the state parameter ω e f f and of the deceleration parameter q as functions of the redshift for a Universe containing collisional and non-collisional dark matter fluids, and we compare both models with the Λ CDM model. As we demonstrate, the resulting picture is well accommodated to the latest observational data on the basis of physical parameters.

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