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Analysis of phase waves in the ECoG data ECoG数据中的相位波分析
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-09-09 DOI: 10.1051/mmnp/2021045
Alexandre Aksenov, A. Beuter
Subdural ECoG data recorded from the matrix of electrodes during syllable pronunciation are analyzed by the method of circular-linear regression. Phase waves in 1D electrode arrays and in the whole 2D set of electrodes are detected, and their spatial organization and temporal evolution are studied. Phase portraits of wave vectors indicate the presence of sources, sinks, and saddle points. The analysis of temporal evolution of phase portraits shows that they changed more at the beginning of syllable pronunciation. Furthermore, wave sources were more stable in their localization during the pronunciation. Overall, in spite of large variability of phase portraits, they represent some characterization of the dynamics of electric potential in the cerebral cortex.
采用循环线性回归方法分析了音节发音过程中电极矩阵记录的声部ECoG数据。检测了一维电极阵列和整个二维电极组中的相位波,并研究了它们的空间组织和时间演化。波矢量的相位图表示源、汇和鞍点的存在。对相位画像时间演变的分析表明,相位画像在音节发音开始时变化较大。此外,在发音过程中,波源的定位更加稳定。总的来说,尽管相位图的变化很大,但它们代表了大脑皮层电位动力学的一些特征。
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引用次数: 2
A mathematical assessment of the efficiency of quarantining and contact tracing in curbing the COVID-19 epidemic 隔离和接触者追踪在遏制COVID-19流行中的有效性的数学评估
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-08-30 DOI: 10.1051/mmnp/2021042
A. Lambert
In our model of the COVID-19 epidemic, infected individuals can be of four types, according whether they are asymptomatic ($A$) or symptomatic ($I$), and use a contact tracing mobile phone app ($Y$) or not ($N$). We denote by $f$ the fraction of $A$'s, by $y$ the fraction of $Y$'s and by $R_0$ the average number of secondary infections from a random infected individual.We investigate the effect of non-digital interventions and of digital interventions, depending on the willingness to quarantine, parameterized by four cooperating probabilities.For a given `effective' $R_0$ obtained with non-digital interventions, we use non-negative matrix theory and stopping line techniques to characterize mathematically the minimal fraction $y_0$ of app users needed to curb the epidemic. We show that under a wide range of scenarios, the threshold $y_0$ as a function of $R_0$ rises steeply from 0 at $R_0=1$ to prohibitively large values (of the order of $60-70%$ up) whenever $R_0$ is above 1.3. Our results show that moderate rates of adoption of a contact tracing app can reduce $R_0$ but are by no means sufficient to reduce it below 1 unless it is already very close to 1 thanks to non-digital interventions.
在我们的COVID-19流行模型中,感染者可以分为四种类型,根据他们是无症状($A$)还是有症状($I$),并使用接触者追踪手机应用程序($Y$)或不使用($N$)。我们用f表示A的分数,用y表示y的分数,用R_0表示随机感染个体的二次感染的平均数量。我们研究了非数字干预和数字干预的影响,这取决于隔离的意愿,由四个合作概率参数化。对于通过非数字干预获得的给定“有效”R_0$,我们使用非负矩阵理论和停止线技术从数学上表征控制疫情所需的应用程序用户的最小分数y_0$。我们表明,在广泛的场景下,阈值$y_0$作为$R_0$的函数从$R_0=1$时的0急剧上升到$R_0$高于1.3时的令人望而却步的大值(约为$60- 70%)。我们的研究结果表明,适度采用接触追踪应用程序可以降低R_0,但绝不足以将其降低到1以下,除非由于非数字干预,R_0已经非常接近1。
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引用次数: 9
Investigation of COVID-19 Mathematical Model Under Fractional Order Derivative 分数阶导数下新冠肺炎数学模型的研究
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-08-24 DOI: 10.1051/mmnp/2021044
K. Shah, M. Arfan, Meshal Shutaywi, Wejdan Deebani, Dumitru Balaneau
The given article is devoted to presentation of some results regarding existence and uniqueness of solution to a fractional order model that addressing the effect of immigration on the transmission dynamics of a population model. Further, in view of this investigation the effect of immigration have been checked on transmission of recent pandemic known as Corona virus COVID-19. The concerned results have been established by using fixed point theory approach. After investigation qualitative analysis of the considered model, by applying Laplace transform along with decomposition method, we have calculated some series type results for the concerned model. The unknown quantities of each equation have been decomposed into small quantities to calculate each small quantity very easily for the series solution by adding first few terms of the said quantities. Approximate results of some testing data with different cases are given to illustrate the results.
本文致力于介绍关于一个分数阶模型解的存在性和唯一性的一些结果,该模型解决了移民对人口模型传播动力学的影响。此外,鉴于这项调查,移民对最近被称为冠状病毒新冠肺炎的大流行传播的影响已得到检查。用不动点理论方法建立了有关结果。在对所考虑的模型进行定性分析后,通过应用拉普拉斯变换和分解方法,我们计算了有关模型的一些级数型结果。每个方程的未知量已经分解成小的量,通过添加所述量的前几项,可以非常容易地为级数解计算每个小的量。给出了一些不同情况下测试数据的近似结果来说明结果。
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引用次数: 0
Invariant measure of stochastic higher order KdV equation driven by Poisson processes 泊松过程驱动的随机高阶KdV方程的不变测度
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-08-23 DOI: 10.1051/MMNP/2021041
Pengfei Xu, Jianhua Huang, Wei Yan
The current paper is devoted to stochastic damped higher order KdV equation driven by Poisson process. We establish the well-posedness of stochastic damped higher-order KdV equation, and prove that there exists an unique invariant measure for non-random initial conditions. Some discussion on the general pure jump noise case are also provided. Some numerical simulations of the invariant measure are provided to support the theoretical results. Mathematics Subject Classification. 60H15, 37L55. Received March 27, 2020. Accepted July 13, 2021.
本文研究了泊松过程驱动的随机阻尼高阶KdV方程。建立了随机阻尼高阶KdV方程的适定性,并证明了对于非随机初始条件存在唯一不变测度。对一般纯跳变噪声情况也作了讨论。给出了一些不变测度的数值模拟来支持理论结果。数学学科分类。60H15, 37L55。收于2020年3月27日。2021年7月13日接受。
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引用次数: 2
Spatiotemporal pattern formation in a prey-predator model with generalist predator 具有通才捕食者的捕食-捕食模型的时空格局形成
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-07-03 DOI: 10.22541/AU.162531612.21576519/V1
Kalyan Manna, M. Banerjee
Generalist predators exploit multiple food sources and it is economicalfor them to reduce predation pressure on a particular prey species whentheir density level becomes comparatively less. As a result, aprey-predator system tends to become more stable in the presence of ageneralist predator. In this article, we investigate the roles of boththe diffusion and nonlocal prey consumption in shaping the populationdistributions for interacting generalist predator and its focal preyspecies. In this regard, we first derive the conditions associated withTuring instability through linear analysis. Then, we perform a weaklynonlinear analysis and derive a cubic Stuart-Landau equation governingamplitude of the resulting patterns near Turing bifurcation boundary.Further, we present a wide variety of numerical simulations tocorroborate our analytical findings as well as to illustrate some othercomplex spatiotemporal dynamics. Interestingly, our study reveals theexistence of traveling wave solutions connecting two spatiallyhomogeneous coexistence steady states in Turing domain under theinfluence of temporal bistability phenomenon. Also, our investigationshows that nonlocal prey consumption acts as a stabilizing force for thesystem dynamics.
多面手捕食者利用多种食物来源,当特定猎物的密度水平相对较低时,对它们来说,减少对特定猎物的捕食压力是经济的。因此,当有多面手捕食者存在时,捕食者-猎物系统趋于稳定。本文研究了扩散和非局部猎物消耗在相互作用的多面手捕食者及其焦点被捕食者种群分布中的作用。在这方面,我们首先通过线性分析得出图灵不稳定性的相关条件。然后,我们进行了弱非线性分析,并在图灵分岔边界附近导出了一个三次Stuart-Landau方程,该方程控制了结果模式的振幅。此外,我们提出了各种各样的数值模拟来证实我们的分析结果,以及说明一些其他复杂的时空动态。有趣的是,我们的研究揭示了在时间双稳现象的影响下,图灵域中连接两个空间均匀共存稳态的行波解的存在性。此外,我们的研究表明,非本地猎物消耗是系统动力学的稳定力量。
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引用次数: 4
Numerical simulation of rigid particles in Stokes flow: lubrication correction for general shapes of particles Stokes流中刚性粒子的数值模拟:对一般形状粒子的润滑修正
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-06-28 DOI: 10.1051/MMNP/2021037
A. Lefebvre-Lepot, Flore Nabet
We address the problem of numerical simulation of suspensions of rigid particles in a Stokes flow. We focus on the inclusion of the singular short range interaction effects (lubrication effects) in the simulations when the particles come close one to another. The problem is solved without introducing new hypothesis nor model. As in Lefebvre-Lepot et al. [J. Fluid Mech. 769 (2015) 369–386], the key idea is to decompose the velocity and pressure flows in a sum of a singular and a regular part. In this article, the singular part is computed using an explicit asymptotic expansion of the solution when the distance goes to zero. This expansion is similar to the asymptotic expansion proposed in Hillairet and Kelai [Asymptotic Anal. 95 (2015) 187–241] but is more appropriate for numerical simulations of suspensions. It can be computed for any locally convex (that is the particles have to be convex close to the contact point) and regular shape of particles. Using Hillairet and Kelai [Asymptotic Anal. 95 (2015) 187–241] as an intermediate result, we prove that the remaining part is regular in the sense that it is bounded independently of the distance. As a consequence, only a small number of degrees of freedom are necessary to obtain accurate results. The method is tested in dimension 2 for clusters of two or three aligned particles with general rigid velocities. We show that, as expected, the convergence is independent of the distance.
研究了斯托克斯流中刚性颗粒悬浮液的数值模拟问题。我们重点研究了当粒子彼此靠近时的奇异短程相互作用效应(润滑效应)在模拟中的包含。这个问题不需要引入新的假设和模型就能解决。如Lefebvre-Lepot et al. [J]。流体力学[j] . 769(2015) 369-386],关键思想是将速度和压力流动分解为奇异部分和正则部分之和。在本文中,奇异部分是用距离趋近于零时解的显式渐近展开来计算的。这种展开式类似于Hillairet和Kelai提出的渐近展开式[asymptotic Anal. 95(2015) 187-241],但更适合于悬架的数值模拟。它可以计算任何局部凸(即粒子必须是靠近接触点的凸)和规则形状的粒子。使用Hillairet和Kelai[渐近分析,95(2015)187-241]作为中间结果,我们证明了剩余部分是正则的,因为它独立于距离有界。因此,只需要少量的自由度就可以获得准确的结果。该方法在二维中测试了具有一般刚性速度的两个或三个排列的粒子簇。我们证明,正如预期的那样,收敛性与距离无关。
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引用次数: 0
Dynamics and control of loop reactors - a review 循环反应器的动力学与控制综述
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-06-14 DOI: 10.1051/MMNP/2021035
M. Sheintuch, O. Nekhamkina
In loop reactors the system is composed of several reactor units that are  organized in a loop and the feeding takes place at one of several ports with switching of the feed port. In its simplest operation a pulse is formed and rotates around it, producing high temperatures which enable combustion of dilute streams.  A limiting model with infinite number of units was derived. Rotating pulses, steady in a moving coordinate, emerge in both models when the switching to front propagation velocities ~1. But this behavior exists over a narrow domain. Simulations were conducted with generic first order Arrhenius kinetics. Experimental observations are reviewed.Outside the narrow frozen rotating pattern domain the system may exhibit multi- or quasi-periodic operation separated by domains of inactive reaction. The bifurcation set incorporates many 'finger'-like domains of complex frequency-locked solutions that allow to extend the operation domain with higher feed temperatures.Control is necessary to attain stable simple rotating frozen pattern within the narrow domains of active operation. Various tested control approaches are reviewed.         Actual implementation of combustion in LR will involve several reactants of different ignition temperatures. Design and control should be aimed at producing locked fronts and avoid extinction of slower reactions.
在环形反应器中,系统由若干个反应器单元组成,这些反应器单元被组织成一个回路,进料在几个端口中的一个进行,进料端口进行切换。在最简单的操作中,形成一个脉冲并围绕它旋转,产生高温,使稀流燃烧成为可能。导出了具有无限单元数的极限模型。当切换到前传播速度~1时,两种模型都出现了在运动坐标中稳定的旋转脉冲。但这种行为存在于一个狭窄的领域。采用一般一级阿伦尼乌斯动力学进行了模拟。回顾了实验观察结果。在狭窄的冷冻旋转模式域之外,系统可能表现出多周期或准周期的操作,这些操作被非活性反应域分开。分岔集包含许多复杂锁频解决方案的“手指”状域,允许在更高的进给温度下扩展操作域。控制是必要的,以获得稳定的简单旋转冻结模式,在狭窄的主动操作范围内。回顾了各种经过测试的控制方法。LR燃烧的实际实施将涉及几种不同点火温度的反应物。设计和控制应旨在产生锁定的前沿,避免较慢的反应消失。
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引用次数: 0
Effects of Heterogeneity and Global Dynamics of Weakly Connected Subpopulations 弱连接亚居群的异质性和全局动态效应
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-06-14 DOI: 10.1051/MMNP/2021034
Derdei Bichara, A. Iggidr, Souâd Yacheur
We develop a method that completely characterizes the global dynamics of models with multiple subpopulations that are weakly interconnected. The method is applied on two classes of models with multiple subpopulations: an epidemic model that involves multiple host species and multiple vector species and a patchy vector-borne model. The method consists of two main steps: reducing the system using tools of large scale systems and studying the dynamics of an auxiliary system related the original system. The developed method determines the underlying dynamics and the ``weight" of each subpopulations with respect to the dynamics of the whole population, and how the topology of the connectivity matrix alters the dynamics of the overall population. The method provides global stability results for all types of equilibria, namely trivial, boundary or interior equilibria.
我们开发了一种方法,该方法完全表征了具有弱互连的多个子种群的模型的全局动力学。该方法应用于两类具有多个子种群的模型:一类是涉及多个宿主物种和多个媒介物种的流行病模型,另一类是斑片状媒介传播模型。该方法包括两个主要步骤:使用大型系统的工具对系统进行简化,以及研究与原始系统相关的辅助系统的动力学。所开发的方法确定了基本动力学和每个子种群相对于整个种群动力学的“权重”,以及连通矩阵的拓扑结构如何改变整个种群的动力学。该方法为所有类型的平衡提供了全局稳定性结果,即平凡平衡、边界平衡或内部平衡。
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引用次数: 2
Three-dimensional phase field model for actin-based cell membrane dynamics 基于肌动蛋白的细胞膜动力学三维相场模型
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-06-03 DOI: 10.1051/mmnp/2021048
M. Hamed, A. Nepomnyashchy
The interface dynamics of a 3D cell immersed in a 3D extracellular matrix is investigated. We suggest a 3D generalization of a known 2D minimal phase field model suggested in Ziebert et al. [J. R. Soc. Interface 9 (2012) 1084–1092] for the description of keratocyte motility. Our model consists of two coupled evolution equations for the order parameter and a three-dimensional vector field describing the actin network polarization (orientation). We derive a closed evolutionary integro-differential equation governing the interface dynamics of a 3D cell. The equation includes the normal velocity of the membrane, its curvature, cell volume relaxation, and a parameter that is determined by the non-equilibrium effects in the cytoskeleton. This equation can be considered as a 3D generalization of the 2D case that was studied in Abu Hamed and Nepomnyashchy [Physica D 408 (2020)].
研究了浸泡在三维细胞外基质中的三维细胞的界面动力学。我们建议对Ziebert等人[J.R.Soc.Interface 9(2012)1084-1092]中提出的已知2D最小相场模型进行3D推广,以描述角膜细胞运动。我们的模型由两个阶参数的耦合进化方程和一个描述肌动蛋白网络极化(取向)的三维矢量场组成。我们导出了一个控制三维细胞界面动力学的闭合进化积分微分方程。该方程包括膜的法向速度、曲率、细胞体积弛豫,以及由细胞骨架中的非平衡效应决定的参数。该方程可以被认为是Abu Hamed和Nepomnyashchy[Physica D 408(2020)]中研究的2D情况的3D推广。
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引用次数: 3
A stability theorem for equilibria of delay differential equations in a critical case with application to a model of cell evolution 临界情况下时滞微分方程平衡点的稳定性定理及其在细胞进化模型中的应用
IF 2.2 4区 数学 Q1 Mathematics Pub Date : 2021-05-04 DOI: 10.1051/MMNP/2021021
karim O. Amin, Irina Badralexi, A. Halanay, R. Mghames
In this paper the stability of the zero equilibrium of a system with time delay is studied. The critical case of a multiple zero root of the characteristic equation of the linearized system is treated by applying a Malkin type theorem and using a complete Lyapunov-Krasovskii functional. An application to a model for malaria under treatment considering the action of the immune system is presented.
本文研究了一类时滞系统的零平衡点的稳定性。应用Malkin型定理和完备的Lyapunov-Krasovskii泛函处理了线性化系统特征方程的多重零根的临界情况。在考虑免疫系统作用的疟疾治疗模型中的应用。
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引用次数: 3
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Mathematical Modelling of Natural Phenomena
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