103,736 research outputs found
Detection of radioactive material entering national ports: A Bayesian approach to radiation portal data
Given the potential for illicit nuclear material being used for terrorism,
most ports now inspect a large number of goods entering national borders for
radioactive cargo. The U.S. Department of Homeland Security is moving toward
one hundred percent inspection of all containers entering the U.S. at various
ports of entry for nuclear material. We propose a Bayesian classification
approach for the real-time data collected by the inline Polyvinyl Toluene
radiation portal monitors. We study the computational and asymptotic properties
of the proposed method and demonstrate its efficacy in simulations. Given data
available to the authorities, it should be feasible to implement this approach
in practice.Comment: Published in at http://dx.doi.org/10.1214/10-AOAS334 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
A New Path-Integral Representation of the -Matrix in Potential Scattering
We employ the method used by Barbashov and collaborators in Quantum Field
Theory to derive a path-integral representation of the -matrix in
nonrelativistic potential scattering which is free of functional integration
over fictitious variables as was necessary before. The resulting expression
serves as a starting point for a variational approximation applied to
high-energy scattering from a Gaussian potential. Good agreement with exact
partial-wave calculations is found even at large scattering angles. A novel
path-integral representation of the scattering length is obtained in the
low-energy limit.Comment: 9 pages, 1 figure, Latex with amsmath, amssym; v2: some typos
corrected, matches published versio
Character-level Intra Attention Network for Natural Language Inference
Natural language inference (NLI) is a central problem in language
understanding. End-to-end artificial neural networks have reached
state-of-the-art performance in NLI field recently.
In this paper, we propose Character-level Intra Attention Network (CIAN) for
the NLI task. In our model, we use the character-level convolutional network to
replace the standard word embedding layer, and we use the intra attention to
capture the intra-sentence semantics. The proposed CIAN model provides improved
results based on a newly published MNLI corpus.Comment: EMNLP Workshop RepEval 2017: The Second Workshop on Evaluating Vector
Space Representations for NL
Spin-triplet s-wave local pairing induced by Hund's rule coupling
We show within the dynamical mean field theory that local multiplet
interactions such as Hund's rule coupling produce local pairing
superconductivity in the strongly correlated regime. Spin-triplet
superconductivity driven by the Hund's rule coupling emerges from the pairing
mediated by local fluctuations in pair exchange. In contrast to the
conventional spin-triplet theories, the local orbital degrees of freedom has
the anti-symmetric part of the exchange symmetry, leaving the spatial part as
fully gapped and symmetric s-wave.Comment: 9 pages, 7 figure
High-speed ultrasound imaging in dense suspensions reveals impact-activated solidification due to dynamic shear jamming
A remarkable property of dense suspensions is that they can transform from
liquid-like at rest to solid-like under sudden impact. Previous work showed
that this impact-induced solidification involves rapidly moving jamming fronts;
however, details of this process have remained unresolved. Here we use
high-speed ultrasound imaging to probe non-invasively how the interior of a
dense suspension responds to impact. Measuring the speed of sound we
demonstrate that the solidification proceeds without a detectable increase in
packing fraction, and imaging the evolving flow field we find that the shear
intensity is maximized right at the jamming front. Taken together, this
provides direct experimental evidence for jamming by shear, rather than
densification, as driving the transformation to solid-like behavior. Based on
these findings we propose a new model to explain the anisotropy in the
propagation speed of the fronts and delineate the onset conditions for dynamic
shear jamming in suspensions.Comment: 9 pages, 3 figure
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