335 research outputs found
PANEL: Challenges for multimedia/multimodal research in the next decade
The multimedia and multimodal community is witnessing an
explosive transformation in the recent years with major
societal impact. With the unprecedented deployment of
multimedia devices and systems, multimedia research is
critical to our abilities and prospects in advancing state-of-theart technologies and solving real-world challenges facing the
society and the nation. To respond to these challenges and
further advance the frontiers of the field of multimedia, this
panel will discuss the challenges and visions that may guide
future research in the next ten years
Acute Myocarditis – A Trigger of Cardiac Autoimmunity? Expected Insights from the Etiology, Titre-Course, and Effect on Survival of Cardiac Autoantibodies (ETiCS) Study
Determination of the complex microwave photoconductance of a single quantum dot
A small quantum dot containing approximately 20 electrons is realized in a
two-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional
transport and microwave spectroscopy reveal the dot's electronic structure. By
applying a coherently coupled two-source technique, we are able to determine
the complex microwave induced tunnel current. The amplitude of this
photoconductance resolves photon-assisted tunneling (PAT) in the non-linear
regime through the ground state and an excited state as well. The out-of-phase
component (susceptance) allows to study charge relaxation within the quantum
dot on a time scale comparable to the microwave beat period.Comment: 5.5 pages, 6 figures, accepted by Phys. Rev. B (Jan. B15 2001
Wavefunction topology of two-dimensional time-reversal symmetric superconductors
We discuss the topology of the wavefunctions of two-dimensional time-reversal
symmetric superconductors. We consider (a) the planar state, (b) a system with
broken up-down reflection symmetry, and (c) a system with general spin-orbit
interaction. We show explicitly how the relative sign of the order parameter on
the two Fermi surfaces affects this topology, and clarify the meaning of the
classification for these topological states.Comment: only the Introduction has been modified from v
A step towards testing general relativity using weak gravitational lensing and redshift surveys
Using the linear theory of perturbations in General Relativity, we express a
set of consistency relations that can be observationally tested with current
and future large scale structure surveys. We then outline a stringent
model-independent program to test gravity on cosmological scales. We illustrate
the feasibility of such a program by jointly using several observables like
peculiar velocities, galaxy clustering and weak gravitational lensing. After
addressing possible observational or astrophysical caveats like galaxy bias and
redshift uncertainties, we forecast in particular how well one can predict the
lensing signal from a cosmic shear survey using an over-lapping galaxy survey.
We finally discuss the specific physics probed this way and illustrate how
gravity models would fail such a test.Comment: 12 pages, 10 figure
Reverse-Engineering a Transcriptional Enhancer: A Case Study in Drosophila
Abstract Enhancers, or cis-regulatory elements, are the principal determinants of spatiotemporal patterning of gene expression. For reasons of clinical and research utility, it is desirable to build customized enhancers that drive novel gene expression patterns, but currently, we largely rely on “found” genomic elements. Synthetic enhancers, assembled from transcription factor binding sites taken from natural signal-regulated enhancers, generally fail to behave like their wild-type counterparts when placed in transgenic animals, suggesting that important aspects of enhancer function are still unexplored. As a step toward the creation of a truly synthetic regulatory element, we have undertaken an extensive structure–function study of an enhancer of the Drosophila decapentaplegic (dpp) gene that drives expression in the developing visceral mesoderm (VM). Although considerable past efforts have been made to dissect the dppVM enhancer, transgenic experiments presented here indicate that its activity cannot be explained by the known regulators alone. dppVM contains multiple, previously uncharacterized, regulatory sites, some of which exhibit functional redundancy. The results presented here suggest that even the best-studied enhancers must be further dissected before they can be fully understood, and before faithful synthetic elements based on them can be created. Implications for developmental genetics, mathematical modeling, and therapeutic applications are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63213/1/ten.tea.2008.0074.pd
Topological Superfluid in one-dimensional Ultracold Atomic System with Spin-Orbit Coupling
We propose a one-dimensional Hamiltonian which supports Majorana
fermions when -wave superfluid appears in the ultracold atomic
system and obtain the phase-separation diagrams both for the
time-reversal-invariant case and time-reversal-symmetry-breaking case. From the
phase-separation diagrams, we find that the single Majorana fermions exist in
the topological superfluid region, and we can reach this region by tuning the
chemical potential and spin-orbit coupling . Importantly, the
spin-orbit coupling has realized in ultracold atoms by the recent experimental
achievement of synthetic gauge field, therefore, our one-dimensional ultra-cold
atomic system described by is a promising platform to find the
mysterious Majorana fermions.Comment: 5 papers, 2 figure
Impedance spectroscopy method for investigation of the polycrystalline inhomogeneous ceramics
Influence of uncorrelated overlayers on the magnetism in thin itinerant-electron films
The influence of uncorrelated (nonmagnetic) overlayers on the magnetic
properties of thin itinerant-electron films is investigated within the
single-band Hubbard model. The Coulomb correlation between the electrons in the
ferromagnetic layers is treated by using the spectral density approach (SDA).
It is found that the presence of nonmagnetic layers has a strong effect on the
magnetic properties of thin films. The Curie temperatures of very thin films
are modified by the uncorrelated overlayers. The quasiparticle density of
states is used to analyze the results. In addition, the coupling between the
ferromagnetic layers and the nonmagnetic layers is discussed in detail. The
coupling depends on the band occupation of the nonmagnetic layers, while it is
almost independent of the number of the nonmagnetic layers. The induced
polarization in the nonmagnetic layers shows a long-range decreasing
oscillatory behavior and it depends on the coupling between ferromagnetic and
nonmagnetic layers.Comment: 9 pages, RevTex, 6 figures, for related work see:
http://orion.physik.hu-berlin.d
Charge Transport Through Open, Driven Two-Level Systems with Dissipation
We derive a Floquet-like formalism to calculate the stationary average
current through an AC driven double quantum dot in presence of dissipation. The
method allows us to take into account arbitrary coupling strengths both of a
time-dependent field and a bosonic environment. We numerical evaluate a
truncation scheme and compare with analytical, perturbative results such as the
Tien-Gordon formula.Comment: 14 pages, 6 figures. To appear in Phys. Rev.
- …