41,847 research outputs found
Fisher's zeros of quasi-Gaussian densities of states
We discuss apparent paradoxes regarding the location of the zeros of the
partition function in the complex plane (Fisher's zeros) of a pure
SU(2) lattice gauge theory in 4 dimensions. We propose a new criterion to draw
the region of the complex plane where reweighting methods can be
trusted when the density of states is almost but not exactly Gaussian. We
propose new methods to infer the existence of zeros outside of this region. We
demonstrate the reliability of these proposals with quasi Gaussian Monte Carlo
distributions where the locations of the zeros can be calculated by independent
numerical methods. The results are presented in such way that the methods can
be applied for general lattice models. Applications to specific lattice models
will be discussed in a separate publication.Comment: 11 pages, 21 figures, with minor correction
Fractional Quantum Hall Effect in Suspended Graphene: Transport Coefficients and Electron Interaction Strength
Strongly correlated electron liquids which occur in quantizing magnetic
fields reveal a cornucopia of fascinating quantum phenomena such as
fractionally charged quasiparticles, anyonic statistics, topological order, and
many others. Probing these effects in GaAs-based systems, where electron
interactions are relatively weak, requires sub-kelvin temperatures and
record-high electron mobilities, rendering some of the most interesting states
too fragile and difficult to access. This prompted a quest for new
high-mobility systems with stronger electron interactions. Recently,
fractional-quantized Hall effect was observed in suspended graphene (SG), a
free-standing monolayer of carbon, where it was found to persist up to T=10 K.
The best results in those experiments were obtained on micron-size flakes, on
which only two-terminal transport measurements could be performed. Here we pose
and solve the problem of extracting transport coefficients of a fractional
quantum Hall state from the two-terminal conductance. We develop a method,
based on the conformal invariance of two-dimensional magnetotransport, and
illustrate its use by analyzing the measurements on SG. From the temperature
dependence of longitudinal conductivity, extracted from the measured
two-terminal conductance, we estimate the energy gap of quasiparticle
excitations in the fractional-quantized nu=1/3 state. The gap is found to be
significantly larger than in GaAs-based structures, signaling much stronger
electron interactions in suspended graphene. Our approach provides a new tool
for the studies of quantum transport in suspended graphene and other nanoscale
systems
Action Recognition Based on Joint Trajectory Maps Using Convolutional Neural Networks
Recently, Convolutional Neural Networks (ConvNets) have shown promising
performances in many computer vision tasks, especially image-based recognition.
How to effectively use ConvNets for video-based recognition is still an open
problem. In this paper, we propose a compact, effective yet simple method to
encode spatio-temporal information carried in skeleton sequences into
multiple images, referred to as Joint Trajectory Maps (JTM), and ConvNets
are adopted to exploit the discriminative features for real-time human action
recognition. The proposed method has been evaluated on three public benchmarks,
i.e., MSRC-12 Kinect gesture dataset (MSRC-12), G3D dataset and UTD multimodal
human action dataset (UTD-MHAD) and achieved the state-of-the-art results
mHealth Series: Factors influencing sample size calculations for mHealth-based studies - A mixed methods study in rural China
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