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This paper is concerned with properties of maximal solutions of the Ricci and cross curvature flows on locally homogeneous three-manifolds of type SL(2,R). We prove that, generically, a maximal solution originates at a sub-Riemannian…

Differential Geometry · Mathematics 2010-01-11 Xiaodong Cao , John Guckenheimer , Laurent Saloff-Coste

With materials of anisotropic electrical conductivity, it is possible to generate a dynamo with a simple velocity field, of the type precluded by Cowling's theorems with isotropic materials. Following a previous study by Ruderman and…

Geophysics · Physics 2020-04-28 Thierry Alboussiere , Kamel Drif , Franck Plunian

In the paper, we study evolution equations of the scalar and Ricci curvatures under the Hamilton's Ricci flow on a closed manifold and on a complete noncompact manifold. In particular, we study conditions when the Ricci flow is trivial and…

Differential Geometry · Mathematics 2020-09-17 Vladimir Rovenski , Sergey Stepanov , Irina Tsyganok

We have introduced a new transfer operator for chaotic flows whose leading eigenvalue yields the dynamo rate of the fast kinematic dynamo and applied cycle expansion of the Fredholm determinant of the new operator to evaluation of its…

chao-dyn · Physics 2009-10-22 N. J. BALMFORTH , P. CVITANOVIC , G. R. IERLEY , E. A. SPIEGEL , G. VATTAY

Let M be an even dimensional compact Riemannian manifold with boundary and let D be a Dirac operator acting on the sections of the Clifford module E over M. We impose certain local elliptic boundary conditions for D obtaining a selfadjoint…

Analysis of PDEs · Mathematics 2017-03-10 Alexander Gorokhovsky , Matthias Lesch

The spectral flow of the low-lying eigenvalues of the improved and unimproved Wilson-Dirac operator is studied on instanton-like configurations and on thermalized quenched configurations at various $\beta$-values and lattice sizes. We also…

High Energy Physics - Lattice · Physics 2007-05-23 Hubert Simma , Douglas Smith

In this paper, we study the Ricci flow on manifolds with boundary. In the first part of the paper, we prove short-time existence and uniqueness of the solution, in which the boundary becomes instantaneously umbilic for positive time. In the…

Differential Geometry · Mathematics 2021-08-10 Tsz-Kiu Aaron Chow

In this work we generalise various recent results on the evolution and monotonicity of the eigenvalues of certain geometric operators under specified geometric flows. Given a closed, compact Riemannian manifold $\big(M^n,g(t)\big)$ and a…

Differential Geometry · Mathematics 2017-06-21 R. R. Mesquita , D. M. Tsonev

We find a local solution to the Ricci flow equation under a negative lower bound for many known curvature conditions. The flow exists for a uniform amount of time, during which the curvature stays bounded below by a controllable negative…

Differential Geometry · Mathematics 2018-06-13 Yi Lai

Following work of Ecker, we consider a weighted Gibbons-Hawking-York functional on a Riemannian manifold-with-boundary. We compute its variational properties and its time derivative under Perelman's modified Ricci flow. The answer has a…

Differential Geometry · Mathematics 2015-05-28 John Lott

We prove that, for a two-dimensional Riemannian manifold, the Ricci flow is obtained by a Wiener process.

Mathematical Physics · Physics 2009-01-30 Marco Frasca

Consider a sequence of pointed n-dimensional complete Riemannian manifolds {(M_i,g_i(t), O_i)} such that t in [0,T] are solutions to the Ricci flow and g_i(t) have uniformly bounded curvatures and derivatives of curvatures. Richard Hamilton…

Differential Geometry · Mathematics 2014-11-11 David Glickenstein

In this work, we use the Ricci flow approach to study the gap phenomenon of Riemannian manifolds with non-negative curvature and sub-critical scaling invariant curvature decay. The first main result is a quantitative Ricci flow existence…

Differential Geometry · Mathematics 2023-08-15 Pak-Yeung Chan , Man-Chun Lee

In this second part of a series of papers on the long-time behavior of Ricci flows with surgery, we establish a bound on the evolution of the infimal area of simplicial complexes inside a 3-manifold under the Ricci flow. This estimate…

Differential Geometry · Mathematics 2018-03-16 Richard H. Bamler

The wavefunction coefficients of conformally coupled scalars in power-law FRW cosmologies satisfy differential equations governed by a set of simple combinatorial rules known as the kinematic flow. In this paper we derive the kinematic…

High Energy Physics - Theory · Physics 2025-08-18 Ross Glew , Andrzej Pokraka

Using direct simulations, weakly nonlinear theory and nonlinear mean-field theory, it is shown that the quenched velocity field of a saturated nonlinear dynamo can itself act as a kinematic dynamo. The flow is driven by a forcing function…

Astrophysics · Physics 2008-11-21 Andreas Tilgner , Axel Brandenburg

We derive one unified formula for Ricci curvature tensor on arbitrary warped product manifold by introducing a new notation for the lift vector and the Levi-Civita connection.This formula is helpful to further consider Ricci flow (RF) and…

Differential Geometry · Mathematics 2015-03-20 Wei-Jun Lu

In this announcement, we exhibit the second variation of Perelman's $\lambda$ and $\nu$ functionals for the Ricci flow, and investigate the linear stability of examples. We also define the "central density" of a shrinking Ricci soliton and…

Differential Geometry · Mathematics 2007-05-23 Huai-Dong Cao , Richard S. Hamilton , Tom Ilmanen

Hamilton's pinching conjecture, that three-dimensional complete non-compact manifolds with pinched Ricci curvature are flat, has recently been resolved using Ricci flow. In this paper we prove a direct analogue of that result in all…

Differential Geometry · Mathematics 2026-03-24 Alix Deruelle , Man-Chun Lee , Felix Schulze , Miles Simon , Peter M. Topping

A formula is given in terms of secondary characteristic classes for the leading order contribution to the spectral flow for a path of twisted Dirac operators on an odd dimensional, Riemannian manifold when the twisting is done by a path of…

Differential Geometry · Mathematics 2007-05-23 Clifford Henry Taubes