Nonlocal Dynamics Research Articles

Dynamics of a multicomponent vesicle in shear flow

We study the fully nonlinear, nonlocal dynamics of two-dimensional multicomponent vesicles in a shear flow with matched viscosity of the inner and outer fluids. Using a nonstiff, pseudo-spectral boundary integral method, we investigate dynamical patterns induced by inhomogeneous bending for a two phase system. Numerical results reveal that there exist novel phase-treading and tumbling mechanisms that cannot be observed for a homogeneous vesicle. In particular, unlike the well-known steady tank-treading dynamics characterized by a fixed inclination angle, here the phase-treading mechanism leads to unsteady periodic dynamics with an oscillatory inclination angle. When the average phase concentration is around 1/2, we observe tumbling dynamics even for very low shear rate, and the excess length required for tumbling is significantly smaller than the value for the single phase case. We summarize our results in phase diagrams in terms of the excess length, shear rate, and concentration of the soft phase. These findings go beyond the well known dynamical regimes of a homogeneous vesicle and highlight the level of complexity of vesicle dynamics in a fluid due to heterogeneous material properties.

Fronts under arrest: Nonlocal boundary dynamics in biology

We introduce a minimal geometric partial differential equation framework to understand pattern formation from interacting, counterpropagating fronts. Our approach concentrates on the interfaces between different states in a system, and relies on both nonlocal interactions and mean-curvature flow to track their evolution. As an illustration, we use this approach to describe a phenomenon in bacterial colony formation wherein sibling colonies can arrest each other's growth. This arrested motion leads to static separations between healthy, growing colonies. As our minimal model faithfully recovers the geometry of these competing colonies, it captures and elucidates the key leading-order mechanisms responsible for such patterned growth.

Toward approximating non-local dynamics in single-point pressure–strain correlation closures

A key hurdle in turbulence modelling is the closure for the pressure–strain correlation. Herein, the challenge stems from the fact that the non-local dynamics due to pressure cannot be comprehensively incorporated in a single-point closure expression. In this article, we analyse different aspects of the dynamics due to pressure for their amenability with the single-point modelling framework. Based on this, an approach is proposed that incorporates a set of pragmatic compromises in the form and the scope of the model to augment the degree of non-local dynamics that may be approximated by a single-point pressure strain correlation model. Thence, this framework is utilized to formulate an illustrative model. The predictions of this model are compared to numerical and experimental data and contrasted against other established closures over a range of homogeneous flows, under diverse conditions. Finally, the regions of validity in anisotropy space for this illustrative model are delineated using the process realizability criteria for different flows.

Fast and accurate implementation of Fourier spectral approximations of nonlocal diffusion operators and its applications

This work is concerned with the Fourier spectral approximation of various integral differential equations associated with some linear nonlocal diffusion and peridynamic operators under periodic boundary conditions. For radially symmetric kernels, the nonlocal operators under consideration are diagonalizable in the Fourier space so that the main computational challenge is on the accurate and fast evaluation of their eigenvalues or Fourier symbols consisting of possibly singular and highly oscillatory integrals. For a large class of fractional power-like kernels, we propose a new approach based on reformulating the Fourier symbols both as coefficients of a series expansion and solutions of some simple ODE models. We then propose a hybrid algorithm that utilizes both truncated series expansions and high order Runge–Kutta ODE solvers to provide fast evaluation of Fourier symbols in both one and higher dimensional spaces. It is shown that this hybrid algorithm is robust, efficient and accurate. As applications, we combine this hybrid spectral discretization in the spatial variables and the fourth-order exponential time differencing Runge–Kutta for temporal discretization to offer high order approximations of some nonlocal gradient dynamics including nonlocal Allen–Cahn equations, nonlocal Cahn–Hilliard equations, and nonlocal phase-field crystal models. Numerical results show the accuracy and effectiveness of the fully discrete scheme and illustrate some interesting phenomena associated with the nonlocal models.

Corporate dynamics of systems of logistic delay equations with large delay control

A system of two logistic equations with delay coupled by delayed control has been considered. It has been shown that, in the case of a fairly large delay control coefficient, the problem of the dynamics of the initial systems has been reduced to investigating the nonlocal dynamics of special families of partial differential equations that do not contain small and large parameters. New interesting dynamic phenomena are discovered based on the results of numerical analysis. Systems of three logistic delay equations with two types of diffusion relations have been considered. Special families of partial differential equations that do not contain small and large parameters have also been constructed for each of these systems. The research results for the dynamic properties of the original equations have been presented. It has been shown that the difference in the dynamics of the considered systems of three equations may be of a fundamental nature.

Influence of imperfect end boundary condition on the nonlocal dynamics of CNTs

Imperfections that unavoidably occur during the fabrication process of carbon nanotubes (CNTs) have a significant influence on the vibration behavior of CNTs. Among these imperfections, the boundary condition defect is studied in this investigation based on the nonlocal elasticity theory. To this end, a mathematical model of the non-ideal end condition in a cantilever CNT is developed by a strongly non-linear spring to study its effect on the vibration behavior. The weak form equation of motion is derived via Hamilton’s principle and solved based on Rayleigh–Ritz approach. Once the frequency response function (FRF) of the CNT is simulated, it is found that the defect parameter injects noise to the FRF in the range of lower frequencies and as a result the small scale effect on the FRF remains undisturbed in high frequency ranges. Besides, in this work a process is introduced to estimate the nonlocal and defect parameters for establishing the mathematical model of the CNT based on FRF, which can be competitive because of its lower instrumentation and data analysis costs. The estimation process relies on the resonance frequencies and the magnitude of noise in the frequency response function of the CNT. The results show that the constructed dynamic response of the system based on estimated parameters is in good agreement with the original response of the CNT.

Low energy signatures of nonlocal field theories

The response of inertial particle detectors coupled to a scalar field satisfying nonlocal dynamics described by nonanalytic functions of the d'Alembertian operator $\Box$ is studied. We show that spontaneous emission processes of a low energy particle detector are very sensitive to high-energy nonlocality scales. This allows us to suggest a nuclear physics experiment ($\sim$ MeV energy scales) that outperforms the sensitivity of LHC experiments by many orders of magnitude. This may have implications for the falsifiability of theoretical proposals of quantum gravity.

A POLYTROPIC MODEL FOR SPACE AND LABORATORY PLASMAS DESCRIBED BY BI-MAXWELLIAN ELECTRON DISTRIBUTIONS

ABSTRACT Non-local electron energy probability functions (EEPFs) are shown to have an important effect on the thermodynamic behavior of plasmas in the context of solar wind and laboratory plasmas. A conservation relation is held for electron enthalpy and plasma potential during the electron transport. For an adiabatic system governed by non-local electron dynamics, the correlation between electron temperature and density can be approximated by a polytropic relation, with different indexes demonstrated using three cases of bi-Maxwellian EEPFs. This scenario differs from a local thermodynamic equilibrium having a single polytropic index of 5/3 for adiabaticity.

Set-membership estimations for the evolution of infectious diseases in heterogeneous populations

The paper presents an approach for set-membership estimation of the state of a heterogeneous population in which an infectious disease is spreading. The population state may consist of susceptible, infected, recovered, etc. groups, where the individuals are heterogeneous with respect to traits, relevant to the particular disease. Set-membership estimations in this context are reasonable, since only vague information about the distribution of the population along the space of heterogeneity is available in practice. The presented approach comprises adapted versions of methods which are known in estimation and control theory, and involve solving parametrized families of optimization problems. Since the models of disease spreading in heterogeneous populations involve distributed systems (with non-local dynamics and endogenous boundary conditions), these problems are non-standard. The paper develops the needed theoretical instruments and a solution scheme. SI and SIR models of epidemic diseases are considered as case studies and the results reveal qualitative properties that may be of interest.

Enhanced quantum nonlocality induced by the memory of a thermal-squeezed environment

We investigate the transient non-Markovian dynamics of quantum nonlocality for a pair of two-level atoms coupled to a common thermal-squeezed environment. We use Bell-CHSH inequality, steering inequality, and entanglement as theoretical tools to investigate the nonlocality dynamics. We see significant differences between the non-Markovian nonlocality dynamics and its Markovian counterpart. We mainly focus on quantum steering nonlocality which has gained much interest recently. An enhanced quantum nonlocality is shown through the violation of steering inequality and entanglement in the non-Markovian regime of the structured environment. A close correspondence is shown between steering nonlocality and entanglement dynamics.

A nonlocal sample dependence SDE-PDE system modeling proton dynamics in a tumor

A nonlocal stochastic model for intra- and extracellular proton dynamics in a tumor is proposed.The intracellular dynamics is governed by an SDE coupled to a reaction-diffusionequation for the extracellular proton concentration on the macroscale. In a more general contextthe existence and uniqueness of solutions for local and nonlocalSDE-PDE systems are established allowing, in particular, to analyze the proton dynamics model, bothin its local version and in the case with nonlocal path dependence.Numerical simulations are performedto illustrate the behavior of solutions, providing some insights into the effects of randomness on tumor acidity.

Gauge invariant nonlocal quantum dynamics of the Aharonov–Bohm effect and how it may be tested

The gauge invariant nonlocal quantum dynamics that is responsible for the Aharonov–Bohm (AB) effect is described. It is shown that it may be verified experimentally.

Dynamics of the logistic equation with two delays

We study the logistic equation with two delays. When studying its nonlocal dynamics, we obtain a condition for the existence and the asymptotics of a relaxation cycle. When studying the local dynamics, we show that the behavior of solutions of the original equation is determined by the structure of solutions of special families of nonlinear boundary value problems of parabolic and degenerate-parabolic type.

Dynamics of bell-nonlocality for two atoms interacting with a vacuum multi-mode noise field

We investigate the internal-state Bell nonlocal entanglement dynamics, as measured by CHSH inequality of two atoms interacting with a vacuum multi-mode noise field by taking into account the spatial degrees of freedom of the two atoms. The dynamics of Bell nonlocality of the atoms with the atomic internal states being initially in a Werner-type state is studied, by deriving the analytical solutions of the Schrödinger equation, and tracing over the degrees of freedom of the field and the external motion of the two atoms. In addition, through comparison with entanglement as measured by concurrence, we find that the survival time of entanglement is much longer than that of the Bell-inequality violation. And the comparison of the quantum correlation time between two Werner-type states is discussed.

Nonlocal dynamics and infinite nonrelativistic conformal symmetries

We study the symmetry of the class of nonlocal models which includes the nonlocal extension of the Pais-Uhlenbeck oscillator. As a consequence, we obtain an infinite-dimensional symmetry algebra, containing the Virasoro algebra, which can be considered as a generalization of the nonrelativistic conformal symmetries to the infinite order. Moreover, this nonlocal extension resembles to some extent the string model, and on the quantum level, it leads to the centrally extended Virasoro algebra.

Spectral dimension from nonlocal dynamics on causal sets

We investigate the spectral dimension obtained from non-local continuum d'Alembertians derived from causal sets. We find a universal dimensional reduction to 2 dimensions, in all dimensions. We conclude by discussing the validity and relevance of our results within the broader context of quantum field theories based on these nonlocal dynamics.

Agentic Networks and Entrepreneurial Opportunities: An Emerging Nonlocal Network Dynamics Perspective

While literature on entrepreneurial strategy has long highlighted that entrepreneurs benefit from having the right network connections, literature on network development has traditionally emphasized “rich-get-richer” dynamics and the role of existing ties informing new socially-proximate ties, a perspective we call structural localism. In contrast, an emerging literature has begun to explore how entrepreneurs purposefully form non-local ties – what we call agentic network change (ANC) – and actively dissolve ties to pursue novel opportunities. In this essay, we describe emerging interest in ANC theory and address some of its limitations including unclear scope and underlying mechanisms. We develop the bounded rationality and resource dependent theoretical foundations of ANC, highlight its applicability to explaining novel opportunity execution, and develop an agenda for future ANC research.

Nanoparticle Shape Evolution and Proximity Effects During Tip-Induced Electrochemical Processes.

Voltage spectroscopies in scanning probe microscopy (SPM) techniques are widely used to investigate the electrochemical processes in nanoscale volumes, which are important for current key applications, such as batteries, fuel cells, catalysts, and memristors. The spectroscopic measurements are commonly performed on a grid of multiple points to yield spatially resolved maps of reversible and irreversible electrochemical functionalities. Hence, the spacing between measurement points is an important parameter to be considered, especially for irreversible electrochemical processes. Here, we report nonlocal electrochemical dynamics in chains of Ag particles fabricated by the SPM tip on a silver ion solid electrolyte. When the grid spacing is small compared with the size of the formed Ag particles, anomalous chains of unequally sized particles with double periodicity evolve. This behavior is ascribed to a proximity effect during the tip-induced electrochemical process, specifically, size-dependent silver particle growth following the contact between the particles. In addition, fractal shape evolution of the formed Ag structures indicates that the growth-limiting process changes from Ag(+)/Ag redox reaction to Ag(+)-ion diffusion with the increase in the applied voltage and pulse duration. This study shows that characteristic shapes of the electrochemical products are good indicators for determining the underlying growth-limiting process, and emergence of complex phenomena during spectroscopic mapping of electrochemical functionalities.

Dynamics of nonlocality in an equidistance cavity coupled by fibers

Entanglement and nonlocality, two most striking features of quantum mechanics, are fundamental resources for quantum information processing. They play an important role in quantum information processing. Therefore, studying the dynamics of quantum nonlocality and entanglement is of importance for both fundamental research and practical applications. In this paper we consider the case that three identical two-level atoms are trapped respectively in the three separated equidistance single-mode cavities, which are placed at the vertices of an equilateral triangle and are coupled by three fibers. Each atom resonantly interacts with cavity via a one-photon hopping. The evolution of the state vector of the system is given by solving the schrodinger equation when the total excitation number of the system equals one. The dynamics of nonlocality in the system is investigated via Mermin-Ardehali-Belinksii-Klyshko (MABK) inequality. By the numerical calculations, the MABK inequality is studied when the initial state vector of three atoms is W state or the initial state vector of three cavities is also W state. The influence of cavity-fiber coupling constant on the MABK inequality is discussed. The evolution curves of the MABK parameters Ba and Bc are plotted. The curves show that Ba and Bc both display periodic oscillations, and their oscillation frequencies all increase with the increase of cavity-fiber coupling constant. Ba and Bc are both larger than 1 when the scaling time gt takes a certain value. The results show that the quantum state of three atoms or that of three cavities displays nonlocality. On the other hand, the nonlocality of three-atom quantum state is strengthened with the increase of cavity-fiber coupling constant.

Wrinkling dynamics of fluctuating vesicles in time-dependent viscous flow.

We study the fully nonlinear, nonlocal dynamics of two-dimensional vesicles in a time-dependent, incompressible viscous flow at finite temperature. We focus on a transient instability that can be observed when the direction of applied flow is suddenly reversed, which induces compressive forces on the vesicle interface, and small-scale interface perturbations known as wrinkles develop. These wrinkles are driven by regions of negative elastic tension on the membrane. Using a stochastic immersed boundary method with a biophysically motivated choice of thermal fluctuations, we investigate the wrinkling dynamics numerically. Different from deterministic wrinkling dynamics, thermal fluctuations lead to symmetry-breaking wrinkling patterns by exciting higher order modes. This leads to more rapid and more realistic wrinkling dynamics. Our results are in excellent agreement with the experimental data by Kantsler et al. [Kantsler et al., Phys. Rev. Lett., 2007, 99, 17802]. We compare the nonlinear simulation results with perturbation theory, modified to account for thermal fluctuations. The strength of the applied flow strongly influences the most unstable wavelength characterizing the wrinkles, and there are significant differences between the results from perturbation theory and the fully nonlinear simulations, which suggests that the perturbation theory misses important nonlinear interactions. Strikingly, we find that thermal fluctuations actually have the ability to attenuate variability of the characteristic wavelength of wrinkling by exciting a wider range of modes than the deterministic case, which makes the evolution less constrained and enables the most unstable wavelength to emerge more readily. We further find that thermal noise helps prevent the vesicle from rotating if it is misaligned with the direction of the applied extensional flow.