On the $L^p$ Spectrum of the Hodge Laplacian on Non-Compact Manifolds

Speaker: 

Professor Nelia Charalambous

Institution: 

UCI

Time: 

Tuesday, September 27, 2005 - 4:00pm

Location: 

MSTB 254

One of the central questions in Geometric Analysis is the
interplay between the curvature of the manifold and the spectrum
of an operator.

In this talk, we will be considering the Hodge Laplacian on
differential forms of any order $k$ in the Banach Space $L^p$. In
particular, under sufficient curvature conditions, it will be
demonstrated that the $L^p\,$ spectrum is independent of $p$ for
$1\!\leq\!p\!\leq\! \infty.$ The underlying space is a
$C^{\infty}$-smooth non-compact manifold $M^n$ with a lower bound
on its Ricci Curvature and the Weitzenb\"ock Tensor. The further
assumption on subexponential growth of the manifold is also
necessary. We will see that in the case of Hyperbolic space the
$L^p$ spectrum does in fact depend on $p.$

As an application, we will show that the spectrum of the Laplacian
on one-forms has no gaps on certain manifolds with a pole and on
manifolds that are in a warped product form. This will be done
under weaker curvature restrictions than what have been used
previously; it will be achieved by finding the $L^1$ spectrum of
the Laplacian.

Time permitting, we will take a short look at an alternative
method for finding the Gaussian Heat kernel bounds for the Hodge
Laplacian via Logarithmic Sobolev Inequalities. Such bounds are
necessary in the proof of the $L^p$ independence.

Global convergence of the Yamabe flow in dimension 6 and higher

Speaker: 

Professor Simon Brendle

Institution: 

Stanford University

Time: 

Tuesday, October 18, 2005 - 3:00pm

Location: 

AP&M 7421 (UCSD)

Let $M$ be a compact manifold of dimension $n \geq 3$. Along the > Yamabe flow, a Riemannian metric on $M$ is deformed according to the > equation $\frac{\partial g}{\partial t} = -(R_g - r_g) \, g$, where $R_g$ > is the scalar curvature associated with the metric $g$ and $r_g$ denotes > the mean value of $R_g$. > > It is known that the Yamabe flow exists for all time. Moreover, if $3 \leq > n \leq 5$ or $M$ is locally conformally flat, then the solution approaches > a metric of constant scalar curvature as $t \to \infty$. I will describe > how this result can be generalized to dimensions $6$ and higher under a > technical condition on the Weyl tensor. The proof requires the > construction of a suitable family of test functions.

The evolution of Minimal Surface constructions since 1978

Speaker: 

Professor Herman Karcher

Institution: 

Univ of Bonn, Germany

Time: 

Thursday, March 10, 2005 - 3:00pm

Location: 

MSTB 254

The lecture will be about complete embedded minimal surfaces in R^3 (some immersed ones help the explanations). Before 1978
very little was known and after 1984 progress became rapid. I will
illustrate with pictures, how observed features of known surfaces
led to new, increasingly abstract, constructions. I will not assume
that the audience consists of minimal surface experts, the lecture
is intended to be understandable by graduate students.

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