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We study surface second-harmonic generation (SHG) from a singular plasmonic structure consisting of touching metallic wires. We use the technique of transformation optics and relate the structure to a rather simpler geometry, a slab…

First, we classify proper biharmonic Hopf real hypersurfaces in $\mathbb{C}P^2$. Next, we classify proper biharmonic real hypersurfaces with two distinct principal curvatures in $\mathbb{C}P^n$, where $n\geq 2$. Finally, we prove that…

Differential Geometry · Mathematics 2019-04-15 Toru Sasahara

We use Busemann functions to construct volume preserving mappings in an asymptotically harmonic manifold. If the asymptotically harmonic manifold satisfies the visibility condition, we construct mappings which preserve distances in some…

Differential Geometry · Mathematics 2022-06-28 Sinhwi Kim , JeongHyeong Park

For any twisted ideal polygon in $\mathbb{H}^3$, we construct a harmonic map from $\mathbb{C}$ to $\mathbb{H}^3$ with a polynomial Hopf differential, that is asymptotic to the given polygon, and is a bounded distance from a pleated plane.…

Differential Geometry · Mathematics 2024-07-12 Subhojoy Gupta , Gobinda Sau

We verify a construction which, for $\Bbb K$ the reals, complex numbers, quaternions, or octonions, builds a spherical $t$-design by placing a spherical $t$-design on each $\Bbb K$-projective or $\Bbb K$-Hopf fiber associated to the points…

Metric Geometry · Mathematics 2025-05-07 Ayodeji Lindblad

It is proved that harmonic functions are characterized by harmonicity of their spherical means, for which purpose the iterated spherical means are used. The similar characterization of solutions to the modified Helmholtz equation…

Analysis of PDEs · Mathematics 2021-10-12 Nikolay Kuznetsov

We prove a stability theorem for the elliptic Harnack inequality: if two weighted graphs are equivalent, then the elliptic Harnack inequality holds for harmonic functions with respect to one of the graphs if and only if it holds for…

Probability · Mathematics 2011-05-23 Richard F. Bass

We give a necessary and sufficient condition for existence of spinc structures on real Bott manifolds.

Differential Geometry · Mathematics 2024-07-02 Anna Gąsior , Rafał Lutowski

In case the stability relation is a congruence, a necessary and also a sufficient condition for its equality with the center congruence is given.

Group Theory · Mathematics 2013-10-01 Vipul Kakkar , R. P. Shukla

Necessary conditions for asymptotic stability and stabilizability of subsets for dynamical and control systems are obtained. The main necessary condition is homotopical and is in turn used to obtain a homological one. A certain extension is…

Dynamical Systems · Mathematics 2022-11-15 Matthew D. Kvalheim

In this paper we construct a new family of harmonic morphisms $\varphi:V^5\to\s^2$, where $V^5$ is a 5-dimensional open manifold contained in an ellipsoidal hypersurface of $\c^4=\r^8$. These harmonic morphisms admit a continuous extension…

Differential Geometry · Mathematics 2009-10-02 S. Montaldo , A. Ratto

We construct a family of Hermitian metrics on the Hopf surface $ \mathbb{S}^3\times \mathbb{S}^1$, whose fundamental classes represent distinct cohomology classes in the Aeppli cohomology group. These metrics are locally conformally…

Differential Geometry · Mathematics 2020-10-13 Jingyi Chen , Liding Huang

We prove a stability theorem for spaces of smooth concordance embeddings. From it we derive various applications to spaces of concordance diffeomorphisms and homeomorphisms.

Algebraic Topology · Mathematics 2025-04-02 Thomas Goodwillie , Manuel Krannich , Alexander Kupers

Let $\Sigma$ and $\bar\Sigma$ be finite alphabets. For topologically transitive sofic systems $ X\subset \Sigma^{\Bbb Z}$ and $\widetilde X\subset \widetilde\Sigma^{\Bbb Z}$ we give a necessary and sufficient condition for the existence of…

Dynamical Systems · Mathematics 2018-01-03 Wolfgang Krieger

We demonstrate that it is conceptually and computationally favorable to regard spin-weighted spherical harmonics as vector valued functions on the total space $SO(3)$ of the Hopf bundle, satisfying a covariance condition with respect to the…

General Relativity and Quantum Cosmology · Physics 2014-03-04 Norbert Straumann

We study Frobenius 1-morphisms $\i$ in an additive bicategory $\c$ satisfying the depth 2 condition. We show that the 2-endomorphism rings $\c^2(\i\x\ib,\i\x\ib)$ and $\c^2(\ib\x\i,\ib\x\i)$ can be equipped with dual Hopf algebroid…

Quantum Algebra · Mathematics 2007-05-23 Gabriella B"ohm , Korn'el Szlach'anyi

This is a preliminary study for bifurcation in fractional order dynamical systems. Stability, persistence and hopf bifurcation are studied. Some studies are also done for functional equations.

Cellular Automata and Lattice Gases · Physics 2008-01-09 Hala El-Saka , E. Ahmed , M. I. Shehata , A. M. A. -El-Sayed

In this paper we study the Lyapunov stability and the Hopf bifurcation in a system coupling an hexagonal centrifugal governor with a steam engine. Here are given sufficient conditions for the stability of the equilibrium state and of the…

Dynamical Systems · Mathematics 2007-05-23 Jorge Sotomayor , Luis Fernando Mello , Denis de Carvalho Braga

We give a classification of quadratic harmonic morphisms between Euclidean spaces (Theorem 2.4) after proving a Rank Lemma. We also find a correspondence between umbilical (Definition 2.7) quadratic harmonic morphisms and Clifford systems.…

dg-ga · Mathematics 2008-02-03 Ye-lin Ou , J. C. Wood

An analysis of necessary conditions for the existence of controlled dynamics with an attractor of a specified topological type is given. It uses the Hopf classification by degree for Gauss maps of manifolds to spheres of the same dimension,…

Optimization and Control · Mathematics 2022-05-13 Efthimios Kappos