We consider the linearization of the three-dimensional water waves equation with surface tension about a flat interface. Using oscillatory integral methods, we prove that solutions of this equation demonstrate dispersive decay at the somewhat surprising rate of $t^{-5/6}$. This rate is due to competition between surface tension and gravitation at $O(1)$ wave numbers and is connected to the fact that, in the presence of surface tension, there is a so-called "slowest wave". Additionally, we combine our dispersive estimates with $L^2$ type energy bounds to prove a family of Strichartz estimates.

We define a family of generalizations of the two-variable quandle polynomial. These polynomial invariants generalize in a natural way to eight-variable polynomial invariants of finite biquandles. We use these polynomials to define a family of link invariants that further generalize the quandle counting invariant.

The well-known Falkner--Skan equation is one of the most important equations in laminar boundary layer theory and is used to describe the steady two-dimensional flow of a slightly viscous incompressible fluid past wedge shaped bodies of angles related to $\lambda\pi/2$, where $\lambda\in \mathbb R$ is a parameter involved in the equation. It is known that there exists $\lambda^{*}<0$ such that the equation with suitable boundary conditions has at least one positive solution for each $\lambda\ge \lambda^{*}$ and has no positive solutions for $\lambda<\lambda^{*}$. The known numerical result shows $\lambda^{*}=-0.1988$. In this paper, $\lambda^{*}\in [-0.4,-0.12]$ is proved analytically by establishing a singular integral equation which is equivalent to the Falkner--Skan equation. The equivalence result provides new techniques to study properties and existence of solutions of the Falkner--Skan equation.

The paper offers a study of the inverse Laplace transforms of the functions $I_n(rs)\{sI_n^{'}(s)\}^{-1}$ where $I_n$ is the modified Bessel function of the first kind and $r$ is a parameter. The present study is a continuation of the author's previous work %[\textit{Canadian Mathematical Bulletin} 45] on the singular behavior of the special case of the functions in question, $r$=1. The general case of $r \in [0,1]$ is addressed, and it is shown that the inverse Laplace transforms for such $r$ exhibit significantly more complex behavior than their predecessors, even though they still only have two different types of points of discontinuity: singularities and finite discontinuities. The functions studied originate from non-stationary fluid-structure interaction, and as such are of interest to researchers working in the area.

Leray's self-similar solution of the Navier-Stokes equations is defined by $$ u(x,t) = U(y)/\sqrt{2\sigma (t^*-t)}, $$ where $y = x/\sqrt{2\sigma (t^*-t)}$, $\sigma>0$. Consider the equation for $U(y)$ in a smooth bounded domain $\mathcal{D}$ of $\mathbb{R}^3$ with non-zero boundary condition: \begin{gather*} -\nu \bigtriangleup U + \sigma U +\sigma y \cdot \nabla U + U\cdot \nabla U + \nabla P = 0,\quad y \in \mathcal{D}, \\ \nabla \cdot U = 0, \quad y \in \mathcal{D}, \\ U = \mathcal{G}(y), \quad y \in \partial \mathcal{D}. \end{gather*} We prove an existence theorem for the Dirichlet problem in Sobolev space $W^{1,2} (\mathcal{D})$. This implies the local existence of a self-similar solution of the Navier-Stokes equations which blows up at $t=t^*$ with $t^* < +\infty$, provided the function $\mathcal{G}(y)$ is permissible.