Special Session 156: Structure and dynamics of solutions for nonlinear elliptic and parabolic equations

Extremal norms of potentials from fixed eigenvalues for Camassa-Holm equations

Jifeng Chu
Hangzhou Normal University
Peoples Rep of China
Co-Author(s):    
Abstract:
We study a kind of reverse spectral problems for Camassa-Holm equations. The aim is to prove the explicit solutions for the extremal $L^1$-norms of the potentials, given the first fixed periodic eigenvalue or any fixed Dirichlet eigenvalue. We use the setting of measure differential equations to understand such problems because the solution will lead to Dirac measure distributions of potentials. The explicit expressions for the sharp bounds are given as some elementary functions.

On ground states to an elliptic problem involving a double phase operator

Marta Garcia Huidobro
Pontificia Universidad Catolica de Chile
Chile
Co-Author(s):    C. Cort\`azar and P.Herreros
Abstract:
This talk is concerned with the uniqueness of radially symmetric ground state solutions to the double phase elliptic problem $$ \mbox{div}\big( a(|x|)|\nabla v|^{q-2}\nabla v+b(|x|)|\nabla v|^{p-2}\nabla v \big)+\mathsf f(v)=0\,,\quad\lim_{|x|\to+\infty}v(x)=0,\quad x\in\mathbb R^n,\eqno{(P)} $$ where $a$ and $b$ are weights satisfying some growth assumptions. For simplicity in this talk we will treat the case of $a(|x|)=|x|^{\tilde\theta}$, and $b(|x|)\equiv 1$, namely \begin{equation}\label{eq2} \begin{gathered} \big(r^{\theta-1}\phi_q( u`)+r^{n-1}\phi_p(u`))`+r^{n-1}f(u)=0\,,\quad r>0\,,\ u`(0)=0\,,\quad\lim\limits_{r\to+\infty}u(r)=0\,, \end{gathered} \end{equation} where $\theta=n+\tilde\theta>1$, $\phi_s(t)=|t|^{s-2}t$, $s>1$, $n>q>p>1$ and $`=\frac{d}{dr}$ . \medskip Regarding the nonlinearity $f\in C(\mathbb R)$, we assume the following \begin{enumerate} \item[$(f_1)$]$f$ is odd, $f(0)=0$, and there exist $0\max\left\{\frac{\theta}{nq}-\frac{1}{n},\frac{1}{p}-\frac{1}{n}\right\}$, \quad for $s>\beta,$ \end{enumerate} Regarding the weight $r^{\theta-1}$ we assume \begin{enumerate} \item[$(w_1)$] $\displaystyle\theta\geq n,\quad \frac{\theta-n}{q-p}

Multi-peak stationary solutions for the Gierer-Meinhardt model on a star shaped graph

Yuta Ishii
Fukuoka University
Japan
Co-Author(s):    
Abstract:
In this talk, we consider the multi-peak stationary solutions for the Gierer-Meinhardt model on a star shaped graph. Here, a star shaped graph is a network-liked domain joining several edges in a single junction. In particular, we are interested in the effect of the geometry of the domain on the location of the spikes.

Asymmetry of positive solutions for the H\`{e}non equation in unbounded domains

Ryuji Kajikiya
Osaka Electro-Communication University
Japan
Co-Author(s):    
Abstract:
We investigate the asymmetry of positive solutions for the H\`{e}non equation in a reflectionally symmetric or a point symmetric domain $\Omega$, which is unbounded but it is getting narrower near the infinity. We call $u(x)$ a least energy solution if it is a minimizer of the Rayleigh quotient associated with the H\`{e}non equation. We shall prove that no least energy solution is reflectionally symmetric and even. Moreover, we prove the existence of a positive solution which has the exact symmetry of reflection.

Bifurcation structure in a prey-predator model with protection zone and directed flux

Kousuke Kuto
Waseda University
Japan
Co-Author(s):    Kazuhiro Oeda
Abstract:
This talk studies a spatial prey-predator model incorporating protection zone for prey and directed predator flux toward high-prey-density regions. We investigate how the interaction between spatial refuge and directed movement influences qualitative structures of solutions. In particular, we analyze bifurcation structures of positive stationary solutions and describe their behavior as the directed flux becomes large. The analysis reveals saddle-node bifurcations and multiplicity of coexistence states generated by the combined effects of protection zone and directed flux. We also discuss the associated nonstationary problem and explain how solvability can be established despite discontinuities arising from the refuge interface. These results clarify how protection mechanism and directed flux jointly organize solution structures in prey-predator systems.

Sturm-Liouville boundary value problems and applications to logistic type population models

Kunquan Lan
Toronto Metropolitan University
Canada
Co-Author(s):    
Abstract:
In the presentation, I`ll present the existence of nonzero nonnegative or strictly positive solutions of the boundary value problems (BVPs) of nonlinear Sturm-Liouville (S-L) differential equation: \begin{equation*} \label{sec1intro} -(p(x)u`(x))`+q(x)u(x)=f(x,u(x)) \quad\mbox{for almost every $x\in [0,1]$} \end{equation*} subject to the separated boundary condition (BC): \begin{equation*} \label{bcintro} \alpha u(0)-\beta u`(0)=0,\quad \gamma u(1)+\delta u`(1)=0, \end{equation*} where $\alpha,\beta,\gamma,\delta\in \mathbb R_{+}$ satisfy $(\alpha+\beta)(\gamma+\delta)>0$ and $f:[0,1]\times\mathbb R_{+}\to \mathbb R$ is allowed to take negative values and may have no lower bounds. A sufficient condition for the linear S-L homogeneous equations subject to the above BC to have only zero solution is provided for the first time. The sufficient conditions are a key toward obtaining both the Green`s functions to such BVPs and uniqueness of solutions for the linear S-L nonhomogeneous BVPs including the one-dimensional elliptic BVPs.

Global continuum of solutions for systems of ODEs with periodic boundary conditions and generalized variable-exponent operators

Raul Manasevich
University of Chile
Chile
Co-Author(s):    Jorge Novoa
Abstract:
We consider nonlinear systems of boundary-value problems in one dimension of the form $$ (\mathcal S(t,u'))'=f(t,u,u',\lambda), $$ subject to periodic boundary value conditions. The function $\mathcal S:[0,T]\times\mathbb R^N\to\mathbb R^N$ is continuous and satisfies $\mathcal S(0,x)=\mathcal S(T,x)$ for all $x\in\mathbb R^N$, the function $f$ is Caratheodory. Furthermore we assume $\mathcal{S}$ satisfies some monotonicity and coercivity conditions, thereby defining a class of generalized variable exponent operators that strictly contains the Musielak Orlicz case. Using an abstract continuation framework and the Leray Schauder degree, we establish the existence of global continuum of nontrivial solutions depending on the parameter $\lambda$. Our approach builds on a degree-theoretic alternative of Fitzpatrick, Massabo, and Pejsachowicz, reducing the evaluation of the Leray Schauder degree to a Brouwer degree. This work shows how monotonicity and coercivity conditions in one dimension allow for continuum of solutions in a setting strictly more general than the Musielak Orlicz framework. Furthermore our results are new even if $\mathcal S$ is independent of $t$.

Asymptotic expansion of the heat content for polyharmonic heat equations

Nobuhito Miyake
Faculty of Mathematics, Kyushu University
Japan
Co-Author(s):    
Abstract:
We consider the asymptotic behavior of the heat content associated with polyharmonic heat equations as time approaches zero. Here, the heat content is defined as the mass of solutions over a fixed smooth compact set with initial data given by the indicator function of this set. More precisely, we derive a higher-order asymptotic expansion of the heat content and provide explicit expressions for the coefficients, which reflect the geometric properties of the boundary. We also discuss a connection between our results and a thresholding algorithm for a geometric evolution equation.

Optimal Resource Allocation in Multi-Patch Models with Sign-Changing Environments

Kentaro NAGAHARA
Institute of Science Tokyo
Japan
Co-Author(s):    
Abstract:
This talk concerns the monostable reaction-diffusion logistic equation, which arises in mathematical biology, and a spatially discretized multi-patch model. The reaction-diffusion logistic equation, also known as the Fisher-KPP equation, has been studied extensively since its introduction as a population-dynamics model (e.g., Skellam, 1951). We focus on optimal resource-allocation strategies that maximize population persistence under a fixed total amount of resources. In particular, we consider environments in which habitat quality (or resource availability) changes sign in a spatially heterogeneous manner. This leads us to study the linearized eigenvalue problem at the trivial steady state and to determine the allocation that maximizes the population's persistence. We prove that any global maximizer of the principal eigenvalue is always of bang-bang type, and this conclusion holds independently of the underlying network structure.

Variational analysis for coupled nonlinear Schr\{o}dinger equations with point interaction

Yuki Osada
Tokyo University of Science
Japan
Co-Author(s):    Alessio Pomponio
Abstract:
In this paper we deal with the following weakly coupled nonlinear Schr\{o}dinger system \begin{align*} \begin{cases} - \Delta_\alpha u + \omega u = |u|^2 u + \beta u |v|^2&\quad \mathrm{in}\ \mathbb{R}^2,\ - \Delta v + \tilde{\omega} v = |v|^2 v + \beta |u|^2 v&\quad \mathrm{in}\ \mathbb{R}^2, \end{cases} \end{align*} where $-\Delta_\alpha$ denotes the Laplacian operator with a point interaction, $\omega$ greater then a suitable positive constant, $\tilde{\omega}>0$, and $\beta\ge 0$. For any $\beta\ge 0$ this system admits the existence of a ground state solution which can have only one nontrivial component or two nontrivial components and which could be regular or singular. We analyse this phenomenon showing how this depends strongly on the parameters.

Gradient trajectories from elastica to heterogeneous elastic curves with non-classical shapes

Masahiro Sakoda
Tohoku University
Japan
Co-Author(s):    Shinya Okabe
Abstract:
In this talk, we will discuss planar closed elastic curves with density-modulated stiffness, which were inspired by experiments on biological membranes. In 2023, Brazda et al. characterized the heterogeneous elastic curves as the critical points of a geometric functional defined as the sum of a generalized bending energy with density-modulated stiffness and a Dirichlet energy for the density, under constraints on the total length and the total mass. Since any elastica with constant density is a trivial critical point in the model of density-dependent elastic curves, the functional can be regarded as a generalization of the classical bending energy. On the other hand, if the coefficient in the generalized elastic energy is non-smooth, the existence of heterogeneous elastic curves with non-classical shapes can be anticipated. The purpose of this talk is to prove (i) the existence of infinitely many heterogeneous closed elastic curves with non-classical shapes, and (ii) the existence of weak gradient trajectories connecting the classical elastica to the heterogeneous elastic curves obtained in (i). This talk is based on a joint work with Professor Shinya Okabe of Tohoku University.

Properties of radial steady states to flux-limited Keller-Segel systems

Takasi Senba
Kanagawa University
Japan
Co-Author(s):    
Abstract:
This talk is based on a joint work with Shohei Kohatsu (Tokyo University of Science). We consider radial solutions to lux-limited Keller-Segel systems with a parameter. If the parameter is bigger than the threshold, the system has blow-up solutions. If the parameter is less than the threshold, the system does not have blow-up solutions. Then, the parameter is closely related to properties of solutions. In this talk, we consider the relation between the parameter and properties of radial steady states.

Generalized Jacobi elliptic functions and their properties

Shingo Takeuchi
Shibaura Institute of Technology
Japan
Co-Author(s):    Hajime Sato, Nagi Suzuki
Abstract:
Jacobi elliptic functions are natural extensions of trigonometric functions and play an important role in expressing exact solutions to certain semilinear ordinary differential equations. In this talk, we introduce a generalization of the Jacobi elliptic functions by replacing certain constants with three parameters (besides the modulus) and investigate their fundamental properties. This class of functions also extends the generalized trigonometric functions introduced by Dr\`{a}bek and Man\`{a}sevich, and is well suited for the study of certain quasilinear ordinary differential equations involving the $p$-Laplacian. We derive differential equations and integral formulas satisfied by the generalized Jacobi elliptic functions, together with binomial-type inequalities of Edmunds--Lang type. If time permits, we also discuss a generalization of Legendre`s relation for their periods, namely, generalized complete elliptic integrals.

On Rayleigh quotients with a parameter for $p$-Laplace equations

Mieko Tanaka
Tokyo University of Science
Japan
Co-Author(s):    Vladimir Bobkov
Abstract:
I`ll talk about the Rayleigh quotients with a parameter for the $p$-Laplacian. It is well known that critical values of the standard Rayleigh quotient corresponds to eigenvalues for the $p$-Laplacian. I introduce that our quotient with a parameter also exhibits similar characteristics as a nonlinear eigenvalue problem. Moreover, I`d like to show that critical points correspond to solutions for $p$-Laplace equation with polynomial nonlinearities by converting it effectively.

The Lam`e equation on the circle and applications to singular limite eigenvalue problems

Toru Wakasa
Kyushu Institute of Technology
Japan
Co-Author(s):    Yasuhito Miyamoto, Kouichi Takemura
Abstract:
It is known that for the Lam`e equation appears in the linearized eigenvalue problems associated with the solutions of nonlinear ODEs. The Lam`e potential is expressed in the Jacobi sn-functions, and it is interesting to consider the case the modulus k is close to 1, from the viewpoint of singular limit problems. In this talk, we will show precise the asymptotic formula of all eigenvalues of Lam`e equations as k to 1 under the periodic boundary condition. Moreover, the asymptotic results will be applied to several linearized eigenvalue problems.

Classification and evolution of bifurcation curves for the one-dimensional perturbed Gelfand problem with the Minkowski-curvature operator

Shin-Hwa Wang
National Tsing Hua University, TAIWAN
Taiwan
Co-Author(s):    Shao-Yuan Huang
Abstract:
We study the classification and evolution of bifurcation curves of positive solutions for the one-dimensional perturbed Gelfand problem with the Minkowski-curvature operator% \begin{equation} \left \{ \begin{array} [c]{l}% -\left( \dfrac{u^{\prime}(x)}{\sqrt{1-\left( u^{\prime}(x)\right) ^{2}}% }\right) ^{\prime}=\lambda \exp \left( \dfrac{au}{a+u}\right) \text{, \ }-L0$ are evolution parameters. We determine the shapes of the bifurcation curves for different positive values $a$ and $L$.

Stability of pinned $p$-elasticae

Kensuke Yoshizawa
Nagasaki University
Japan
Co-Author(s):    Tatsuya Miura
Abstract:
Euler's elastica is a critical point of the bending energy under the fixed length constraint, and its $L^p$-counterpart is called $p$-elastica. In this talk, I will present a characterization of the stability of $p$-elasticae under the pinned boundary condition. The key ingredient is a new ``cut-and-paste'' method that does not rely on the second variation but instead exploits the geometric invariance of the functional. This talk is based on joint work with Tatsuya Miura (Kyoto University).