Search

We study the dynamics of the classical solutions of a three-species hybrid competition system in a spatially heterogeneous environment. The species compete for resources using different strategies: the first species disperses nonlocally, the second locally, whereas the third does not disperse. When the environment has a sink area, we show that the non-dispersing species wins the competition, driving the others to extinction. However, in the absence of a sink area, all the species coexist, and there is a continuum of positive coexistence steady states. We also examine the dynamics of the classical solutions of a consumer–resource system comprising a non-dispersing single resource species whose density function evolves and is consumed by three competitors in a hybrid competition model. In this case, we also show that when the habitat has a sink area, the competition favors the non-dispersing species. However, all the competitors coexist when there is no sink area. [ABSTRACT FROM AUTHOR]

Nonlinear coupled reaction-diffusion systems often arise in cooperative processes of chemical kinetics and biochemical reactions. Owing to these potential applications, this article presents an efficient and simple meshless approximation scheme to analyze the solution behavior of a two-dimensional coupled Brusselator system. On considering radial basis functions in the localized settings, meshless shape functions owing Kronecker delta function property are constructed to discretize the spatial derivatives in the time-dependent partial differential equation (PDE). A system of first-order ordinary differential equations (ODEs), obtained after spatial discretization, is then integrated in time via a high-order ODE solver. The proposed scheme's convergence, stability, and efficiency are theoretically established and numerically verified on several benchmark problems. The outcomes verify reliability, accuracy, and simplicity of the proposed scheme against the available methods in the literature. Some recommendations are made regarding time-step size under different node distributions and RBFs. [ABSTRACT FROM AUTHOR]

In this paper, we consider a version of the mathematical model introduced in (Wang et al. in Commun. Nonlinear Sci. Numer. Simul. 42:571–584, 2017) to describe the interaction between vegetation and soil water in arid environments. The model corresponds to a nonlinear parabolic coupled system of partial differential equations, with non-flux boundary conditions, which incorporates, in addition to the natural diffusion of water and plants, a cross-diffusion term given by the hydraulic diffusivity due to the suction of water by the roots. The model also considers a monotonously decreasing vegetation death rate capturing the infiltration feedback between plants and ground water. We first prove the existence and uniqueness of global solutions in a large class of initial data, allowing non-regular ones. These solutions are in a mild setting and under additional regularity assumptions on the initial data and the domain, they are classical. Second, we propose a fully discrete numerical scheme, based on a semi-implicit Euler discretization in time and finite element discretization (with "mass-lumping") in space, for approximating the solutions of the continuous model. We prove the well-posedness of the numerical scheme and some qualitative properties of the discrete solutions including, positivity, uniform weak and strong estimates, convergence towards strong solutions and optimal error estimates. Finally, we present some numerical experiments in order to showcase the good behavior of the numerical scheme including the formation of Turing patterns, as well as to validate the convergence order in the error estimates obtained in the theoretical analysis. [ABSTRACT FROM AUTHOR]

In the past several decades, much attention has been focused on the effects of dispersal on total populations of species. In Zhang (EL 20:1118–1128, 2017), a rigorous biological experiment was performed to confirm the mathematical conclusion: Dispersal tends to enhance populations under a suitable hypothesis. In addition, mathematical models keeping track of resource dynamics in population growth were also proposed in Zhang (EL 20:1118–1128, 2017) to understand this remarkable phenomenon. In these models, the self-regulated quantity “loss rate" of the population seems, in general, difficult to measure experimentally. Our main goal in this paper is to study the effects of relations between the loss rate and the resources, the role of dispersal, and the impact of their interactions on total populations. We compare the total population for small and large diffusion under various correlations between loss rate and the resources. Biological evidence seems to support some specific correlations between the loss rate and the resources. [ABSTRACT FROM AUTHOR]

A reaction–diffusion system governing the predator–prey interaction with specialist predator and herd behavior for prey is investigated. Linear stability of the interior equilibrium is studied, and conditions guaranteeing the occurrence of Turing instability, induced by cross‐diffusion, are found, with a full characterization of the Turing instability region in the parameter space. Numerical simulations on the obtained results are provided. [ABSTRACT FROM AUTHOR]

The use of mathematical models for the study of infectious diseases provides a detailed analysis of their propagation dynamics and impact over time, offering valuable nformation for decision-making. In this work, an SIRS epidemic spatio-temporal model is investigated within a reaction-diffusion system involving susceptible, infected and recovered individuals, with cross-diffusion. A nonlinear incidence rate is applied in this model, determining the existence of a stable limit cycle that emerges from a Hopf bifurcation. In addition, the effect of cross diffusion on the spatio-temporal evolution of the spatially homogeneous periodic solution is analysed. Theoretical results suggest the existence of spatio-temporal oscillatory patterns in the epidemiological model. [ABSTRACT FROM AUTHOR]

This paper investigates pattern formation in 2-component reaction–diffusion systems with linear diffusion and local reaction terms. We propose a novel instability framework characterized by 0-mode Hopf instability, m and m + 1 mode Turing instabilities in 2-component reaction–diffusion systems. A normal form for the codimension 3 bifurcation is derived via the center manifold reduction, representing one of the main results in this paper. Additionally, we present numerical results on the bifurcation of certain reaction–diffusion systems and on the chaotic behavior of the normal form. [ABSTRACT FROM AUTHOR]

We investigate a predator-prey model within two-dimensional heterogeneous environments under no-flux boundary conditions. The populations are assumed to undergo horizontal and vertical movements with varying probabilities, representing different dispersal strategies. In contrast to random diffusion systems, this system exhibits increased complexity in its dynamics. Anisotropic diffusion offers a broader range of possibilities, enabling the prey to more effectively adapt to available resources. We examine the stability of the semitrivial solutions through eigenvalue analysis and abstract persistence theory. By employing degree theory and bifurcation theory, we establish the existence of positive steady states in this system. Furthermore, our numerical results offer valuable insights and intuition for further research. [ABSTRACT FROM AUTHOR]

In this article, we study weighted Stepanov-like pseudo-almost automorphic functions with infinite delay using measure theory. We present a new concept of weighted ergodic functions, which is more general than the classical one. Then, we establish many interesting results on the space of such functions. We also study the existence and uniqueness of (μ,ν)\left(\mu ,\nu )-Stepanov-like pseudo-almost automorphic solutions of infinite class in the α\alpha -norm for some partial functional differential equations in a Banach space with unbounded delay, using the spectral decomposition of the phase space developed by Adimy and his co-authors. An example is given to illustrate this work.

ABSTRACT In this article, we analyze new properties of auto‐wave solutions in fractional reaction‐diffusion systems. These new properties arise due to a change in fractional derivative order and do not occur in systems with classical derivatives. It is shown that the stability of steady‐state solutions and their evolution are mainly determined by the eigenvalue spectrum of a linearized system and the fractional derivative order. It is also demonstrated that the basic properties of auto‐wave solutions in fractional‐order systems can essentially differ from those in standard systems. The results of the linear stability analysis are confirmed by computer simulations of the generalized fractional van der Pol–FitzHugh–Nagumo mathematical model. A common picture of possible instabilities and auto‐wave solutions in time‐fractional two‐component activator‐inhibitor systems is presented. [ABSTRACT FROM AUTHOR]

This paper is devoted to the study of a nonlocal reaction–diffusion model of Chikungunya disease with periodic time delays. We establish two threshold type results on the global dynamics for the growth of mosquitoes and the disease transmission, respectively. Further, we obtain the global attractivity of a positive steady state for a simplified nonlocal and time-delayed system with constant coefficients. We also conduct numerical simulations for the Chikungunya transmission in Ceará, Brazil to investigate the effects of spatial heterogeneity on the disease transmission. [ABSTRACT FROM AUTHOR]

Population ecology theory is replete with density-dependent processes. However, trait-mediated or behavioral indirect interactions can both reinforce or oppose density-dependent effects. This paper presents the first two species competitive ODE and PDE systems, where the non-consumptive behavioral fear effect and the Allee effect, a density-dependent process, are both present. The stability of the equilibria is discussed analytically using the qualitative theory of ordinary differential equations. It is found that the Allee effect and the fear effect change the extinction dynamics of the system and the number of positive equilibrium points, but they do not affect the stability of the positive equilibria. We also observe standard co-dimension one bifurcation in the system by varying the Allee or fear parameter. Interestingly, we find that the Allee effect working in conjunction with the fear effect can bring about several dynamical changes to the system with only fear. There are three parametric regimes of interest in the fear parameter. For small and intermediate amounts of fear, the Allee + fear effect opposes dynamics driven by the fear effect. However, for large amounts of fear the Allee + fear effect reinforces the dynamics driven by the fear effect. The analysis of the corresponding spatially explicit model is also presented. To this end, the comparison principle for parabolic PDE is used. The conclusions of this paper have strong implications for conservation biology, biological control as well as the preservation of biodiversity. [ABSTRACT FROM AUTHOR]

Keywords: Attractors; homogenization; reaction-diffusion system; nonlinear equations; weak convergence; randomly perforated domains; random porous medium; topological space; compactness.GraphBy Kuanysh A. Bekmaganbetov; Gregory A. Chechkin and Vladimir V. ChepyzhovReported by Author; Author; Author [Extracted from the article]

The present paper is concerned with a fractional parabolic reaction-diffusion system posed in a regular bounded open subset of R N , where the gradients of the unknowns act as source terms (see (S) below). First, we establish some nonexistence and blow-up in finite time results. Second, we prove some new weighted regularity results. Such results are interesting in themselves and play a crucial role to study local existence of nonnegative solutions to our system under suitable assumptions on the data. This work also highlights a substantial difference between the nonlocal case and the local case already studied by the fourth author and his coworkers. [ABSTRACT FROM AUTHOR]

In this paper, we present an approach to characterizing fast-reaction limits of systems with nonlinear diffusion, when there are either two reaction–diffusion equations, or one reaction–diffusion equation and one ordinary differential equation, on unbounded domains. Here, we replace the terms of the form u x x in usual reaction–diffusion equation, which represent linear diffusion, by terms of form ϕ (u) x x , representing nonlinear diffusion. We prove the convergence in the fast-reaction limit k → ∞ that is determined by the unique solution of a certain scalar nonlinear diffusion problem. [ABSTRACT FROM AUTHOR]

This study explores the identical synchronization of drive-response neural networks consisting of n different reaction-diffusion systems with arbitrary structures. Specifically, the drive network is made up of n reaction-diffusion systems of FitzHugh-Nagumo type, while the response network contains n reaction-diffusion systems of Hindmarsh-Rose type. Despite the arbitrary topological structures of these two complex networks, we develop a nonlinear adaptive controller to achieve the desired synchronization. Additionally, the paper presents numerical results to validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The intricate relationship between temporal and spatiotemporal dynamics in a Crowley–Martin predator–prey model, enriched with fear effect and anti-predator behavior, is investigated in this study. A careful mathematical analysis is conducted to explore the feasible equilibria of the model system, followed by an examination of their stability, instability, and all possible bifurcation scenarios. Asymptotic stability, bistability, and various codimension-1 and codimension-2 bifurcations, including transcritical, saddle–node, Hopf, cusp, and Bogdanov–Takens bifurcations, are demonstrated by the model. The analytical findings and the model's applications are validated through numerical simulations, employing a biparameter bifurcation diagram for quantitative analysis. The study also observes bubbling phenomena and a scenario leading to the density-dependent hydra effect. The diffusion effect is investigated with special attention to the system's nonlinearity and chosen parameter values. Numerical simulations reveal the emergence of spatiotemporal patterns both within and beyond the Turing space. The evolution of diffusion-driven pattern generation, including cold spots, stripes, labyrinthines, mixtures of stripes and cold spots, and complex non-Turing patterns, is demonstrated on the plane. These spatial patterns are shown to be influenced biologically by both the fear effect and anti-predator behavior. [ABSTRACT FROM AUTHOR]

This paper takes a reaction-diffusion predator-prey system with ratio-dependent Holling III functional response function and Leslie-Gower term into consideration. First of all, the system model is proposed on the basis of basic biological assumptions and previous work, and the existence conditions of the equilibrium point of the system are discussed. Secondly, under the assumption of the existence of equilibrium point, the Turing instability necessary conditions induced by diffusion are investigated. Thirdly, optimal control theory is derived, and the adjoint system and the first-order optimization condition are established. Fourthly, parameter identification based on optimal control is studied, and the technique is extended to network structure. Finally, extensive numerical simulations, including Turing pattern, Normalized Population High Distribution Area (NPHDA) diagram and parameter identification, are carried out to illustrate and validate the analytical results. For the system dynamics phenomena, the results from different perspectives effectively demonstrate that the theoretical findings, numerical simulations and natural reality are identical. In terms of the parameter identification of continuous model and network model, the efficiency and accuracy of various algorithms are fully tested. • This paper proposes and investigates index normalized population height distribution area. • The optimal control problem of reaction-diffusion predator-prey system is formally derived. • The parameter identification research is extended to population network structure space. [ABSTRACT FROM AUTHOR]

This paper is the first to propose an allelopathic phytoplankton competition ODE model influenced by the fear effect based on natural biological phenomena. It is shown that the interplay of this fear effect and the allelopathic term cause rich dynamics in the proposed competition model, such as global stability, transcritical bifurcation, pitchfork bifurcation, and saddle-node bifurcation. We also consider the spatially explicit version of the model and prove analogous results. Numerical simulations verify the feasibility of the theoretical analysis. The results demonstrate that the primary cause of the extinction of non-toxic species is the fear of toxic species compared to toxins. Allelopathy only affects the density of non-toxic species. The discussion guides the conservation of species and the maintenance of biodiversity. [ABSTRACT FROM AUTHOR]

In 1952, Alan Turing accomplished a pioneering theoretical study to show that the coupling of nonlinear chemical reactions and diffusion leads to the instability of spatially homogeneous states. The activator and inhibitor are synthesized as intermediates of the reaction system in the Turing model. Turing found that spatially periodic stationary concentration patterns are spontaneously generated when the diffusion coefficient of the activator is lower than that of the inhibitor. The first experimental realization of the Turing pattern was achieved in 1990 in a chlorite-iodide-malonic acid (CIMA) reaction system. Iodide and chlorite anions act as the activator and inhibitor of this reaction system, respectively. Although there is no significant difference in the diffusion coefficient of iodide and chlorite anions, the Turing pattern was generated because starch was added to the gel reactor to enhance the color tone. This formed a complex with iodide to inhibit its diffusion to satisfy the condition for the Turing instability. Several examples were found after this finding. We focused on the high affinity of quaternary alkyl ammonium cations to iodide. The CIMA reaction was performed in an open gel reactor by adding a quaternary alkyl ammonium cationic surfactant. In addition, the polymer gel consists of the quaternary alkyl ammonium group as the side chain was utilized for the open gel reactor. The micelles of the surfactants and the polymer gels trapped iodide in their vicinity as a counter anion to lower the effective diffusivity to satisfy the condition for the Turing instability. [ABSTRACT FROM AUTHOR]

In this paper, a novel parabolic system involving nonlinear and nonhomogeneous partial differential operator with variable growth structure is introduced for investigating the image denoising and restoration. More precisely, our model is based on regularizing the classical models involving variable exponent operators by considering a nonlinear operator with double phase flux. We begin by investigating theoretically the solvability to the parabolic system under consideration. Under the setting of Musielak-Orlicz spaces, we build a suitable functional framework to study the proposed system. Therefore, we develop the Faedo-Galerkin approach to demonstrate the existence and uniqueness of a weak solution to our model. To illustrate our theoretical results in the context of image noise removal, we present various numerical implementations on some grayscale images. To enrich these simulations, we test the robustness efficiency of the proposed model in the so-called Magnetic Resonance Images (MRI). The obtained numerical results claim that our model is more efficient and robust against noise, in comparison (visually and quantitatively) to some existing state-of-the-art methods. • A novel nonlinear parabolic system is introduced. • The theoretical results are applied to the image denoising and restoration. • Various numerical implementations on some grayscale images are carried out. [ABSTRACT FROM AUTHOR]

Solutions having the form of a diffusion wave propagating in a medium at rest with a finite velocity to a nonlinear parabolic reaction–diffusion system are constructed and studied. A problem of initiating a diffusion wave by boundary conditions specified on a sphere (circular cylindrical surface) is considered in the cases of spherical and cylindrical symmetry for the first time. An existence and uniqueness theorem for a solution in the class of analytical functions is proven. An exact solution is constructed in the form of explicit formulas. A step-by-step iterative algorithm based on the collocation method and expansion in radial basis functions is proposed. Numerical calculations are performed, and their results are verified using the exact solution. [ABSTRACT FROM AUTHOR]

In this paper, we prove the existence of a solution of a novel free boundary problem for reaction-diffusion systems describing growth of biological tissues due to cell influx and proliferation. For this aim, we transform it into a problem with fixed boundary, through a change of variables. The new problem thus obtained has space and time dependent coefficients with nonlinear terms. We then prove the existence of a solution for the corresponding linear problem, and deduce the existence of a solution for the nonlinear problem using the fixed point theorem. Finally, we return to the problem with free boundary to conclude the existence of its solution. [ABSTRACT FROM AUTHOR]

We consider the long-time behaviour of a West Nile virus (WNv) model consisting of a reaction–diffusion system with free boundaries. Such a model describes the spreading of WNv with the free boundary representing the expanding front of the infected region, which is a time-dependent interval $[g(t), h(t)]$ in the model (Lin and Zhu, Spatial spreading model and dynamics of West Nile virus in birds and mosquitoes with free boundary. J. Math. Biol. 75, 1381–1409, 2017). The asymptotic spreading speed of the front has been determined in Wang et al. (Spreading speed for a West Nile virus model with free boundary. J. Math. Biol. 79, 433–466, 2019) by making use of the associated semi-wave solution, namely $\lim _{t\to \infty } h(t)/t=\lim _{t\to \infty }[\!-g(t)/t]=c_\nu$ , with $c_\nu$ the speed of the semi-wave solution. In this paper, by employing new techniques, we significantly improve the estimate in Wang et al. (Spreading speed for a West Nile virus model with free boundary. J. Math. Biol. 79, 433–466, 2019): we show that $h(t)-c_\nu t$ and $g(t)+c_\nu t$ converge to some constants as $t\to \infty$ , and the solution of the model converges to the semi-wave solution. The results also apply to a wide class of analogous Ross–MacDonold epidemic models. [ABSTRACT FROM AUTHOR]

In the paper, the existence of a stable stationary solution in a reaction-diffusion system with slow and fast components in a two-dimensional spatial variable case is investigated. The theorem of the existence of a stationary solution with boundary layers in the case of Dirichlet boundary conditions is proven, its asymptotic approximation is constructed, and conditions for Lyapunov asymptotic stability of this solution are obtained. The research is based on the asymptotic method of differential inequalities, applied to a new class of problems. This result is practically important both for various applications described by similar systems and for the application of numerical stationing methods when solving elliptical boundary value problems. [ABSTRACT FROM AUTHOR]

In 1952, Turing proposed the mechanism of pattern formation in which a stable equilibrium of some kinetic system is destabilized by diffusion. This mechanism is called Turing's instability, which is one of important mechanisms to organize spatiotemporal patterns. In the case of two-component reaction–diffusion systems, the diffusion coefficients should be different for Turing's instability. Conversely, there exist several chemical models that produce the stable patterns even though the diffusion coefficients are equal. These are often referred to as "far-from-equilibrium phenomenon". To study the pattern formation by equal diffusion, this article presents an example of a kinetic system with a asymptotically stable equilibrium, while the corresponding reaction–diffusion system has a family of unstable stationary solutions that is arbitrarily close to the homogeneous stationary solution. [ABSTRACT FROM AUTHOR]

We are interested in generating surfaces with arbitrary roughness and forming patterns on the surfaces. Two methods are applied to construct rough surfaces. In the first method, some superposition of wave functions with random frequencies and angles of propagation are used to get periodic rough surfaces with analytic parametric equations. The amplitude of such surfaces is also an important variable in the provided eigenvalue analysis for the Laplace--Beltrami operator and in the generation of pattern formation. Numerical experiments show that the patterns become irregular as the amplitude and frequency of the rough surface increase. For the sake of easy generalization to closed manifolds, we propose a second construction method for rough surfaces, which uses random nodal values and discretized heat filters. We provide numerical evidence that both surface construction methods yield comparable patterns to those observed in real-life animals. [ABSTRACT FROM AUTHOR]

Neurons can exhibit various rhythmic activities such as bursting, spiking, and quiescent states when exposed to external input current stimulus. In this paper, a model of medicinal leech's heart (LH) interneuron is considered to describe the dynamics of neurons with a varied range of electrical activities. The crucial insights into the model's dynamics are explored in three different parameter regimes: phasic spiking, regular spiking, and bursting, based upon the codimension-one bifurcation of the model by considering V K 2 s h i f t as a bifurcation parameter. The spatiotemporal dynamics of the model are explored by allowing 1D and 2D diffusion in the membrane voltage. The 1D diffusive system produces irregular bursting dynamics for the intermediate value of diffusion coefficients, whereas, at higher values, it shows synchronized oscillations. In the presence of 2D diffusion, the emergence of different types of spiral patterns is observed in the system. Furthermore, the system is extended by incorporating electromagnetic induction in the membrane voltage to explore the effect of induction on the various dynamics of neural model. By varying its intensities, the membrane voltage in the extended model produces a variety of discharge modes, such as periodic spiking, fast-spiking, resting, and spike-adding phenomena. In addition, the emergence of anti-spiral patterns in the extended model near subcritical Hopf bifurcation is analytically verified using the complex Ginzburg-Landau equation (CGLE). These findings demonstrate that the firing patterns vary based on the control parameters, and these variations contribute to our understanding of how the brain system transmits and processes the signals. • A slow-fast neuron model of Leech's heart interneuron is considered. • The model is improved by adding EMI to study the impact of magnetic flux. • Bifurcation scenarios and different firing activities of both models are performed. • These systems with diffusion display irregular firing and multi-arm spiral patterns. • CGLE analysis in the system with EMI confirms anti-spiral patterns occurrence. [ABSTRACT FROM AUTHOR]

We consider a mathematical model of the initiation and development of atherosclerosis in the early stage, defined in different domains. The existence of nonnegative weak solutions is proved via studying an auxiliary system with absolute value terms and applying a novel semi-discrete, operator splitting numerical scheme. Numerical simulations were performed in an idealized two-dimensional geometry in order to verify our assumptions in model building and theoretical analysis. The framework we developed can also be used for nonlinear reaction–diffusion systems defined in other different domains with more complex coupling conditions. [ABSTRACT FROM AUTHOR]

The recently introduced Theory of the Adjacent Possible (TAP) is a model of combinatorial innovation aiming to explain the "hockey-stick" upward trend of human technological evolution, where an explosion in the number of produced items with increasing complexity suddenly occurs. In addition, the TAP model was also used to explain the rapidly emerging biological complexity. Inspired by TAP here we propose a reaction–diffusion system aiming to extend the model in both space and time. We show that the new model exhibits similar characteristics to the TAP model, like the sudden increase in the production of items, after a longer period of slow growth. The new model also exhibits wave propagation of "innovation", resulting in self-sustained complex interference patterns. [ABSTRACT FROM AUTHOR]

In this paper, we propose a spatiotemporal prey-predator model with fear and Allee effects. We first establish the global existence of solution in time and provide some sufficient conditions for the existence of non-negative spatially homogeneous equilibria. Then, we study the stability and bifurcation for the non-negative equilibria and explore the bifurcation diagram, which revealed that the Allee effect and fear factor can induce complex bifurcation scenario. We discuss that large Allee effect-driven Turing instability and pattern transition for the considered system with the Holling-Ⅰ type functional response, and how small Allee effect stabilizes the system in nature. Finally, numerical simulations illustrate the effectiveness of theoretical results. The main contribution of this work is to discover that the Allee effect can induce both codimension-one bifurcations (transcritical, saddle-node, Hopf, Turing) and codimension-two bifurcations (cusp, Bogdanov-Takens and Turing-Hopf) in a spatiotemporal predator-prey model with a fear factor. In addition, we observe that the circular rings pattern loses its stability, and transitions to the coldspot and stripe pattern in Hopf region or the Turing-Hopf region for a special choice of initial condition.

In the current manuscript, a two-patch model with the Allee effect and nonlinear dispersal is presented. We study both the ordinary differential equation (ODE) case and the partial differential equation (PDE) case here. In the ODE model, the stability of the equilibrium points and the existence of saddle-node bifurcation are discussed. The phase diagram and bifurcation curve of our model are also given as a results of numerical simulation. Besides, the corresponding linear dispersal case is also presented. We show that, when the Allee effect is large, high intensity of linear dispersal is not favorable to the persistence of the species. We further show when the Allee effect is large, nonlinear diffusion is more beneficial to the survival of the population than linear diffusion. Moreover, the results of the PDE model extend our findings from discrete patches to continuous patches.

Time-delay effect and bifurcation phenomenon are important topics in the study of reaction–diffusion equations. In this paper, we consider a three-species predator–prey system with diffusion and incubation delay for predator. The stability and Hopf bifurcation are mainly discussed. We conclude that there exists a critical value of delay, such that the internal equilibrium is stable or unstable as the delay crosses the critical value. Especially, the system emerges Hopf bifurcation phenomenon at this critical value. For bifurcation solution, the conclusions of stability, period and bifurcation direction are also presented. Additionally, numerical simulations are proceeded to support the main results. In biology, the existence of bifurcation solution means that when the delay of predator reaches to a certain extent, the predator and prey will coexist within a period of time. It turns out that the related computations and analyses are much more complicated than that of two-species time-delay systems.

In the high friction limit, the initial works of the diffusion–reaction system utilising the one-dimensional Smoluchowski equation have been largely explored by a perfect trap term and a relevant system potential. The fast electronic relaxation process in a polar solvent can best be understood using the perfect sink model. The exact dynamics, however, are only available when the trap is placed in the harmonic potential centre. To solve the model equation for the arbitrary placement of the trap, here we have proposed a fresh, slightly uncommon approach. Additionally, we gave exact results to a recently investigated linear confined-type potential for the perfect trap placed arbitrarily. When the trap is positioned at an uphill location relative to the initial distribution, notable non-monotonic effects of the decay properties have been identified for the variation of potential strength. [ABSTRACT FROM AUTHOR]

We analyze a reaction-diffusion system on RN which models the dispersal of individuals between two exchanging environments for its diffusive component and incorporates a Fujita-type growth for its reactive component. The originality of this model lies in the coupling of the equations through diffusion, which, to the best of our knowledge, has not been studied in Fujita-type problems. We first consider the underlying diffusive problem, demonstrating that the solutions converge exponentially fast towards those of two uncoupled equations, featuring a dispersive operator that is somehow a combination of Laplacians. By subsequently adding Fujita-type reaction terms to recover the entire system, we identify the critical exponent that separates systematic blow-up from possible global existence. [ABSTRACT FROM AUTHOR]

We consider a system of two reaction-diffusion equations in a bounded domain of the -dimensional space with Neumann boundary conditions on the boundary for which the reaction terms and depend on two parameters and . Assume that the system has a spatially homogeneous solution , with and , where is the Jacobian of the corresponding linearized system in the diffusionless approximation and is a smooth monotonically increasing function. We propose some method for the analytical description of the domain of necessary and sufficient conditions of Turing instability on the plane of system parameters for a fixed diffusion coefficient . Also, we show that the domain of necessary conditions of Turing instability on the plane is bounded by the zero-trace curve, the discriminant curve, and the locus of points . Explicit expressions are found for the curves of sufficient conditions and we prove that the discriminant curve is the envelope of the family of these curves. It is shown that one of the boundaries of the Turing instability domain consists of the fragments of the curves of sufficient conditions and is expressed in terms of the function and the eigenvalues of the Laplace operator in the domain under consideration. We find the points of intersection of the curves of sufficient conditions and show that their abscissas do not depend on the form of and are expressed in terms of the diffusion coefficient and the eigenvalues of the Laplace operator. In the special case . For this case, the range of wave numbers at which Turing instability occurs is indicated. We obtain some partition of the semiaxis into half-intervals each of which corresponds to its own minimum critical wave number. The points of intersection of the curves of sufficient conditions lie on straight lines independent of the diffusion coefficient . By way of applications of the statements proven, we consider the Schnakenberg system and the Brusselator equations. [ABSTRACT FROM AUTHOR]

In this paper, we prove global-in-time existence of strong solutions to a class of fractional parabolic reaction–diffusion systems posed in a bounded domain of R N . The nonlinear reactive terms are assumed to satisfy natural structure conditions which provide nonnegativity of the solutions and uniform control of the total mass. The diffusion operators are of type u i ↦ d i (- Δ) s u i where 0 < s < 1 . Global existence of strong solutions is proved under the assumption that the nonlinearities are at most of polynomial growth. Our results extend previous results obtained when the diffusion operators are of type u i ↦ - d i Δ u i . On the other hand, we use numerical simulations to examine the global existence of solutions to systems with exponentially growing right-hand sides, which remains so far an open theoretical question even in the case s = 1 . [ABSTRACT FROM AUTHOR]