204,179 research outputs found
Kazhdan's Property T and C*-algebras
Kazhdan's notion of property T has recently been imported to the C-world
by Bekka. Our objective is to extend a well known fact to this realm; we show
that a nuclear C-algebra with property T is finite dimensional (for all
intents and purposes). Though the result is not surprising, the proof is
significantly more complicated than the discrete group case.Comment: There was a mistake in the first draft, hence some preliminary
results were removed. The proof of the main result, however, is unaffected. 5
page
Dynamos in Stellar Convection Zones: of Wreaths and Cycles
We live near a magnetic star whose cycles of activity are driven by dynamo
action beneath the surface. In the solar convection zone, rotation couples with
plasma motions to build highly organized magnetic fields that erupt at the
surface and undergo relatively regular cycles of polarity reversal. Despite our
proximity to the Sun, the nature of its dynamo remains elusive, but
observations of other solar-type stars show that surface magnetism is a nearly
ubiquitous feature. In recent time, numerical simulations of convection and
dynamo action have taken tremendous strides forward. Global-scale organization
and cyclic magnetism are being achieved by several groups in distinctly
different solar and stellar simulations. Here I will talk about advances on the
numerical front including wreath-building dynamos which may occupy stellar
convection zones. I will discuss the interplay between the new simulations,
various classes of mean-field models, and current and upcoming solar and
stellar observations.Comment: 10 pages, 5 figures, a4 format; proceedings for SOHO 24/GONG 2010
conference: "A new era of seismology of the Sun and solar-like stars,"
Aix-en-Provence, France, June 27-July 4, 2010 (JPCS
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