Necessary and sufficient conditions are presented for several families of planar curves to form a set of stable sampling for the Bernstein space $mathcal{B}_{Omega}$ over a convex set $Omega subset mathbb{R}^2$. These conditions essentially describe
the mobile sampling property of these families for the Paley-Wiener spaces $mathcal{PW}^p_{Omega},1leq p<infty$.
The surface growth model, $u_t + u_{xxxx} + partial_{xx} u_x^2 =0$, is a one-dimensional fourth order equation, which shares a number of striking similarities with the three-dimensional incompressible Navier--Stokes equations, including the results r
egarding existence and uniqueness of solutions and the partial regularity theory. Here we show that a weak solution of this equation is smooth on a space-time cylinder $Q$ if the Serrin condition $u_xin L^{q}L^q (Q)$ is satisfied, where $q,qin [1,infty ]$ are such that either $1/q+4/q<1$ or $1/q+4/q=1$, $q<infty$.
Cantor sets are constructed from iteratively removing sections of intervals. This process yields a cumulative distribution function (CDF), constructed from the invariant measure associated with their iterated function systems. Under appropriate assum
ptions, we identify sampling schemes of such CDFs, meaning that the underlying Cantor set can be reconstructed from sufficiently many samples of its CDF. To this end, we prove that two Cantor sets have almost-nowhere (with respect to their respective invariant measures) intersection.
Let $M^n$ be a closed Riemannian manifold on which the integral of the scalar curvature is nonnegative. Suppose $mathfrak{a}$ is a symmetric $(0,2)$ tensor field whose dual $(1,1)$ tensor $mathcal{A}$ has $n$ distinct eigenvalues, and $mathrm{tr}(mat
hcal{A}^k)$ are constants for $k=1,cdots, n-1$. We show that all the eigenvalues of $mathcal{A}$ are constants, generalizing a theorem of de Almeida and Brito cite{dB90} to higher dimensions. As a consequence, a closed hypersurface $M^n$ in $S^{n+1}$ is isoparametric if one takes $mathfrak{a}$ above to be the second fundamental form, giving affirmative evidence to Cherns conjecture.
Based on the general form of entanglement witnesses constructed from separable states, we first show a sufficient condition of violating the structural physical approximation (SPA) conjecture [Phys. Rev. A 78, 062105 (2008)]. Then we discuss the SPA
conjecture for decomposable entanglement witnesses. Moreover, we make geometric illustrations of the connection between entanglement witnesses and the sets of quantum states, separable states, and entangled states comparing with planes and vectors in Euclidean space.