Positive solutions for a class of singular quasilinear Schrödinger equations with critical Sobolev exponent

We prove the existence of positive solutions of the following singular quasilinear Schrödinger equations at critical growth

$?\mathrm{\Delta }u?\lambda c(x)u?\kappa \alpha (\mathrm{\Delta }(|u{|}^{2\alpha }))|u{|}^{2\alpha ?2}u=|u{|}^{q?2}u+|u{|}^{2^{?}?2}u,u\in D^{1,2}({\mathbb{R}}^N),$

via variational methods, where $\lambda \ge 0$, $c:{\mathbb{R}}^N\to {\mathbb{R}}^{+}$, $\kappa >0$, $0<\alpha <1/2$, $2<q<2^{?}$. It is interesting that we do not need to add a weight function to control $|u{|}^{q?2}u$.     

Decomposition of Schramm–Loewner evolution along its curve

We show that, for $\kappa \in (0,8)$, the integral of the laws of two-sided radial SLE${}_{\kappa }$ curves through different interior points against a measure with SLE${}_{\kappa }$ Green’s function density is the law of a chordal SLE${}_{\kappa }$ curve, biased by the path’s natural length. We also show that, for $\kappa >0$, the integral of the laws of extended SLE${}_{\kappa }(?8)$ curves through different interior points against a measure with a closed formula density restricted in a bounded set is the law of a chordal SLE${}_{\kappa }$ curve, biased by the path’s capacity length restricted in that set. Another result is that, for $\kappa \in (4,8)$, if one integrates the laws of two-sided chordal SLE${}_{\kappa }$ curves through different force points on $\mathbb{R}$ against a measure with density on $\mathbb{R}$, then one also gets a law that is absolutely continuous w.r.t. that of a chordal SLE${}_{\kappa }$ curve. To obtain these results, we develop a framework to study stochastic processes with random lifetime, and improve the traditional Girsanov’s Theorem.     

Dynamical behavior of solutions of a reaction–diffusion model in river network

In this paper, we study the long-time behavior of solutions of a reaction–diffusion model in a one-dimensional river network, where the river network has two branches, and the water flow speeds in each branch are the same constant $\beta$. We show the existence of two critical values $c_0$ and 2 with $0<c_0<2$, and prove that when $-c_0\le \beta <2$, the population density in every branch of the river goes to 1 as time goes to infinity; when $-2<\beta <-c_0$, then, as time goes to infinity, the population density in every river branch converges to a positive steady state strictly below 1; when $\left|\beta \right|\ge 2$, the species will be washed down the stream, and so locally the population density converges to 0. Our result indicates that only if the water-flow speed is suitably small (i.e., $\left|\beta \right|<2$), the species will survive in the long run.     

A new blow-up criterion for the 2D full compressible Navier–Stokes equations without heat conduction in a bounded domain

This paper is to derive a new blow-up criterion for the 2D full compressible Navier–Stokes equations without heat conduction in terms of the density $\rho$ and the pressure $P$. More precisely, it indicates that in a bounded domain the strong solution exists globally if the norm $\left|\right|\rho {\left|\right|}_{L^{\infty }(0,t;L^{\infty })}+\left|\right|P{\left|\right|}_{L^{p_0}(0,t;L^{\infty })}<\infty$ for some constant  $p_0$ satisfying $1<p_0\le 2$. The boundary condition is imposed as a Navier-slip boundary one and the initial vacuum is permitted. Our result extends previous one which is stated as $\left|\right|\rho {\left|\right|}_{L^{\infty }(0,t;L^{\infty })}+\left|\right|P{\left|\right|}_{L^{\infty }(0,t;L^{\infty })}<\infty$.     

The component counts of random functions

Consider functions $f:A\to A\cup C$, where A and C are disjoint finite sets. The weakly connected components of the digraph of such a function are cycles of rooted trees, as in random mappings, and isolated rooted trees. Let $n_1=|A|$ and $n_3=|C|$. When a function is chosen from all ${(n_1+n_3)}^{n_1}$ possibilities uniformly at random, then we find the following limiting behaviour as $n_1\to \infty$. If $n_3=o(n_1)$, then the size of the maximal mapping component goes to infinity almost surely; if $n_3～\gamma n_1$, $\gamma >0$ a constant, then process counting numbers of mapping components of different sizes converges; if $n_1=o(n_3)$, then the number of mapping components converges to 0 in probability. We get estimates on the size of the largest tree component which are of order $\log ?n_3$ when $n_3～\gamma n_1$ and constant when $n_3～n_1^{\alpha }$, $\alpha >1$. These results are similar to ones obtained previously for random injections, for which the weakly connected components are cycles and linear trees.     

Nonlinear stochastic time-fractional slow and fast diffusion equations on Rd

This paper studies the nonlinear stochastic partial differential equation of fractional orders both in space and time variables: $\left({?}^{\beta }+\frac{\nu }{2}{(?\Delta )}^{\alpha ∕2}\right)u(t,x)=I_t^{\gamma }\left[\rho \left(u(t,x)\right)\stackrel{?}{W}(t,x)\right],t>0,x\in {\mathbb{R}}^d,$where $\stackrel{?}{W}$ is the space–time white noise, $\alpha \in (0,2]$, $\beta \in (0,2)$, $\gamma \ge 0$ and $\nu >0$. Fundamental solutions and their properties, in particular the nonnegativity, are derived. The existence and uniqueness of solution together with the moment bounds of the solution are obtained under Dalang’s condition: $d<2\alpha +\frac{\alpha }{\beta }min(2\gamma ?1,0)$. In some cases, the initial data can be measures. When $\beta \in (0,1]$, we prove the sample path regularity of the solution.     

Uniqueness of critical points and maximum principles of the singular minimal surface equation

We consider a smooth solution $u>0$ of the singular minimal surface equation $\sqrt{1+|Du{|}^2}\text{ div}(Du/\sqrt{1+|Du{|}^2})=\alpha /u$ defined in a bounded strictly convex domain of ${\mathbb{R}}^2$ with constant boundary condition. If $\alpha <0$, we prove the existence a unique critical point of u. We also derive some $C^0$ and $C^1$ estimates of u by using the theory of maximum principles of Payne and Philippin for a certain family of Φ-functions. Finally we deduce an existence theorem of the Dirichlet problem when $\alpha <0$.     

On cycles in regular 3-partite tournaments

A $c$-partite tournament is an orientation of a complete $c$-partite graph. In 2006, Volkmann conjectured that every arc of a regular 3-partite tournament $D$ is contained in an $m$-, $(m+1)$- or $(m+2)$-cycle for each $m\in \{3,4,\dots ,\left|V\left(D\right)\right|?2\}$, and this conjecture was proved to be correct for $3\le m\le 7$. In 2012, Xu et al. conjectured that every arc of an $r$-regular 3-partite tournament $D$ with $r\ge 2$ is contained in a $(3k?1)$- or $3k$-cycle for $k=2,3,\dots ,r$. They proved that this conjecture is true for $k=2$. In this paper, we confirm this conjecture for $k=3$, which also implies that Volkmann’s conjecture is correct for $m=7,8$.     

Limit theorems for a class of critical superprocesses with stable branching

We consider a critical superprocess $\{X;{\mathbf{P}}_{\mu }\}$ with general spatial motion and spatially dependent stable branching mechanism with lowest stable index ${\gamma }_0>1$. We first show that, under some conditions, ${\mathbf{P}}_{\mu }(\left|X_t\right|\ne 0)$ converges to 0 as $t\to \infty$ and is regularly varying with index ${({\gamma }_0-1)}^{-1}$. Then we show that, for a large class of non-negative testing functions $f$, the distribution of $\{X_t\left(f\right);{\mathbf{P}}_{\mu }\left(\cdot \right|6X_{t}6\ne 0)\}$, after appropriate rescaling, converges weakly to a positive random variable ${\mathbf{z}}^{({\gamma }_0-1)}$ with Laplace transform $E\left[e^{-u{\mathbf{z}}^{({\gamma }_0-1)}}\right]=1-{(1+u^{-({\gamma }_0-1)})}^{-1∕({\gamma }_0-1)}.$     

Compactness of sign-changing solutions to scalar curvature-type equations with bounded negative part

We consider the equation ${\mathrm{\Delta }}_{g}u+hu=|u{|}^{2^{?}?2}u$ in a closed Riemannian manifold $(M,g)$, where $h\in C^{0,\theta }(M)$, $\theta \in (0,1)$ and $2^{?}=\frac{2n}{n?2}$, $n:=\dim ?(M)\ge 3$. We obtain a sharp compactness result on the sets of sign-changing solutions whose negative part is a priori bounded. We obtain this result under the conditions that $n\ge 7$ and $h<\frac{n?2}{4(n?1)}{\text{Scal}}_g$ in M, where ${\text{Scal}}_g$ is the Scalar curvature of the manifold. We show that these conditions are optimal by constructing examples of blowing-up solutions, with arbitrarily large energy, in the case of the round sphere with a constant potential function h.     

A note on uniqueness of the ground state for nonlinear Schrödinger equations

We are concerned with the following nonlinear Schrödinger equation $-{\epsilon }^2\Delta u+V\left(x\right)u={\left|u\right|}^{p-2}u,u\in H^1\left({\mathbb{R}}^N\right),$where $N\ge 3$, $2<p<\frac{2N}{N-2}$. For $\epsilon$ small enough and a class of $V\left(x\right)$, we show the uniqueness of the positive ground state under certain assumptions on asymptotic behavior of $V\left(x\right)$ and its first derivatives. Here our results are suitable for a kind of $V\left(x\right)$ which has different increasing rates at different directions.     

Asymptotic behavior and blow-up of solutions for infinitely degenerate semilinear parabolic equations with logarithmic nonlinearity

In this paper, we study the initial-boundary value problem for infinitely degenerate semilinear parabolic equations with logarithmic nonlinearity $u_t?{△}_{X}u=u\log ?|u|$, where $X=(X_1,X_2,?,X_m)$ is an infinitely degenerate system of vector fields, and ${△}_X:={\sum }_{j=1}^m{X}_j^2$ is an infinitely degenerate elliptic operator. Using potential well method, we first prove the invariance of some sets and vacuum isolating of solutions. Then, by the Galerkin method and the logarithmic Sobolev inequality, we obtain the global existence and blow-up at +∞ of solutions with low initial energy or critical initial energy, and we also discuss the asymptotic behavior of the solutions.     

Existence and nonexistence of positive solutions for a static Schrödinger–Poisson–Slater equation

In this paper we study the following type of the Schrödinger–Poisson–Slater equation with critical growth

$?△u+(u^2?\frac{1}{|4\pi x|})u=\mu |u{|}^{p?1}u+|u{|}^{4}u,\text{in}{\mathbb{R}}^3,$

where $\mu >0$ and $p\in (11/7,5)$. For the case of $p\in (2,5)$. We develop a novel perturbation approach, together with the well-known Mountion–Pass theorem, to prove the existence of positive ground states. For the case of $p=2$, we obtain the nonexistence of nontrivial solutions by restricting the range of μ and also study the existence of positive solutions by the constrained minimization method. For the case of $p\in (11/7,2)$, we use a truncation technique developed by Brezis and Oswald [9] together with a measure representation concentration-compactness principle due to Lions [27] to prove the existence of radial symmetrical positive solutions for $\mu \in (0,{\mu }^{?})$ with some ${\mu }^{?}>0$. The above results nontrivially extend some theorems on the subcritical case obtained by Ianni and Ruiz [18] to the critical case.