2,604 research outputs found
Irreducible Induced Representations of Fell Bundle C*-Algebras
We give precise conditions under which irreducible representations associated
to stability groups induce to irreducible representations for Fell bundle
C*-algebras. This result generalizes an earlier result of Echterhoff and the
second author. Because the Fell bundle construction subsumes most other
examples of C*-algebras constructed from dynamical systems, our result
percolates down to many different constructions including the many flavors of
groupoid crossed products.Comment: Minor changes suggested by the referee. The paper is accepted for
publication in Trans. Amer. Math. So
Invertibility in groupoid C*-algebras
Given a second-countable, Hausdorff, \'etale, amenable groupoid G with
compact unit space, we show that an element a in C*(G) is invertible if and
only if \lambda_x(a) is invertible for every x in the unit space of G, where
\lambda_x refers to the "regular representation" of C*(G) on l_2(G_x). We also
prove that, for every a in C*(G), there exists some x in G^{(0)} such that
||a|| = ||\lambda_x(a)||.Comment: 8 page
A Classic Morita Equivalence Result for Fell Bundle C*-algebras
We show how to extend a classic Morita Equivalence Result of Green's to the
\cs-algebras of Fell bundles over transitive groupoids. Specifically, we show
that if p:\B\to G is a saturated Fell bundle over a transitive groupoid
with stability group at u\in \go, then \cs(G,\B) is Morita
equivalent to \cs(H,\CC), where \CC=\B\restr H. As an application, we show
that if p:\B\to G is a Fell bundle over a group and if there is a
continuous -equivariant map \sigma:\Prim A\to G/H, where is the
\cs-algebra of \B and is a closed subgroup, then \cs(G,\B) is Morita
equivalent to \cs(H,\CC^{I}) where \CC^{I} is a Fell bundle over whose
fibres are A/I\sme A/I-\ib s and . Green's
result is a special case of our application to bundles over groups.Comment: 10 Pages. Paper has been slightly reorganized and reformatted to
appear in Math. Scand
The Dixmier-Douady Classes of Certain Groupoid -Algebras with Continuous Trace
Given a locally compact abelian group , we give an explicit formula for
the Dixmier--Douady invariant of the -algebra of the groupoid extension
associated to a \v{C}ech -cocycle in the sheaf of germs of continuous
-valued functions. We then exploit the blow-up construction for groupoids to
extend this to some more general central extensions of \'etale equivalence
relations
ContextVP: Fully Context-Aware Video Prediction
Video prediction models based on convolutional networks, recurrent networks,
and their combinations often result in blurry predictions. We identify an
important contributing factor for imprecise predictions that has not been
studied adequately in the literature: blind spots, i.e., lack of access to all
relevant past information for accurately predicting the future. To address this
issue, we introduce a fully context-aware architecture that captures the entire
available past context for each pixel using Parallel Multi-Dimensional LSTM
units and aggregates it using blending units. Our model outperforms a strong
baseline network of 20 recurrent convolutional layers and yields
state-of-the-art performance for next step prediction on three challenging
real-world video datasets: Human 3.6M, Caltech Pedestrian, and UCF-101.
Moreover, it does so with fewer parameters than several recently proposed
models, and does not rely on deep convolutional networks, multi-scale
architectures, separation of background and foreground modeling, motion flow
learning, or adversarial training. These results highlight that full awareness
of past context is of crucial importance for video prediction.Comment: 19 pages. ECCV 2018 oral presentation. Project webpage is at
https://wonmin-byeon.github.io/publication/2018-ecc
A Model of Heat Conduction
We define a deterministic ``scattering'' model for heat conduction which is
continuous in space, and which has a Boltzmann type flavor, obtained by a
closure based on memory loss between collisions. We prove that this model has,
for stochastic driving forces at the boundary, close to Maxwellians, a unique
non-equilibrium steady state
0-level Vacuum Packaging RT Process for MEMS Resonators
A new Room Temperature (RT) 0-level vacuum package is demonstrated in this
work, using amorphous silicon (aSi) as sacrificial layer and SiO2 as structural
layer. The process is compatible with most of MEMS resonators and Resonant
Suspended-Gate MOSFET [1] fabrication processes. This paper presents a study on
the influence of releasing hole dimensions on the releasing time and hole
clogging. It discusses mass production compatibility in terms of packaging
stress during back-end plastic injection process. The packaging is done at room
temperature making it fully compatible with IC-processed wafers and avoiding
any subsequent degradation of the active devices.Comment: Submitted on behalf of EDA Publishing Association
(http://irevues.inist.fr/EDA-Publishing
Helioseismic analysis of the solar flare-induced sunquake of 2005 January 15
We report the discovery of one of the most powerful sunquakes detected to
date, produced by an X1.2-class solar flare in active region 10720 on 2005
January 15. We used helioseismic holography to image the source of seismic
waves emitted into the solar interior from the site of the flare. Acoustic
egression power maps at 3 and 6 mHz with a 2 mHz bandpass reveal a compact
acoustic source strongly correlated with impulsive hard X-ray and
visible-continuum emission along the penumbral neutral line separating the two
major opposing umbrae in the -configuration sunspot that predominates
AR10720. The acoustic emission signatures were directly aligned with both hard
X-ray and visible continuum emission that emanated during the flare. The
visible continuum emission is estimated at J,
approximately 500 times the seismic emission of J. The
flare of 2005 January 15 exhibits the same close spatial alignment between the
sources of the seismic emission and impulsive visible continuum emission as
previous flares, reinforcing the hypothesis that the acoustic emission may be
driven by heating of the low photosphere. However, it is a major exception in
that there was no signature to indicate the inclusion of protons in the
particle beams thought to supply the energy radiated by the flare. The
continued strong coincidence between the sources of seismic emission and
impulsive visible continuum emission in the case of a proton-deficient
white-light flare lends substantial support to the ``back -- warming''
hypothesis, that the low photosphere is significantly heated by intense Balmer
and Paschen continuum-edge radiation from the overlying chromosphere in
white-light flares.Comment: 12 pages, 7 figures, published in MNRA
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