4,982 research outputs found
Diagrammatic Exponentiation for Products of Wilson Lines
We provide a recursive diagrammatic prescription for the exponentiation of
gauge theory amplitudes involving products of Wilson lines and loops. This
construction generalizes the concept of webs, originally developed for eikonal
form factors and cross sections with two eikonal lines, to general soft
functions in QCD and related gauge theories. Our coordinate space arguments
apply to arbitrary paths for the lines.Comment: 16 pages, 4 figures; minor corrections, version to appear in Phys.
Rev.
Full Resolution Image Compression with Recurrent Neural Networks
This paper presents a set of full-resolution lossy image compression methods
based on neural networks. Each of the architectures we describe can provide
variable compression rates during deployment without requiring retraining of
the network: each network need only be trained once. All of our architectures
consist of a recurrent neural network (RNN)-based encoder and decoder, a
binarizer, and a neural network for entropy coding. We compare RNN types (LSTM,
associative LSTM) and introduce a new hybrid of GRU and ResNet. We also study
"one-shot" versus additive reconstruction architectures and introduce a new
scaled-additive framework. We compare to previous work, showing improvements of
4.3%-8.8% AUC (area under the rate-distortion curve), depending on the
perceptual metric used. As far as we know, this is the first neural network
architecture that is able to outperform JPEG at image compression across most
bitrates on the rate-distortion curve on the Kodak dataset images, with and
without the aid of entropy coding.Comment: Updated with content for CVPR and removed supplemental material to an
external link for size limitation
Nutrient overload, insulin resistance, and ribosomal protein S6 kinase 1, S6K1
Nutrient overload leads to obesity, insulin resistance, and often type 2 diabetes. Whereas increased fat intake is commonly cited as the major factor in diet-induced dysmetabolic states, increased protein consumption also contributes, through elevated circulating amino acids. Recent studies have revealed that ribosomal protein S6 kinase 1, S6K1, an effector of mTOR, is sensitive to both insulin and nutrients, including amino acids. Although S6K1 is an effector of growth, recent reports show that amino acids also negatively affect insulin signaling through mTOR/S6K1 phosphorylation of IRS1. Moreover, rather than signaling through the class 1 PI3K pathway, amino acids appear to mediate mTOR activation through class 3 PI3K, or hVps34. Consistent with this, infusion of amino acids into humans leads to S6K1 activation, inhibition of insulin-induced class 1 PI3K activation, and insulin resistance. Thus, S6K1 may mediate deleterious effects, like insulin resistance, and potentially type 2 diabetes in the face of nutrient excess
Substructure of high-p_T Jets at the LHC
We study high-pt jets from QCD and from highly-boosted massive particles such
as tops, W, Z and Higgs, and argue that infrared-safe observables can help
reduce QCD backgrounds. Jets from QCD are characterized by different patterns
of energy flow compared to the products of highly-boosted heavy particle
decays, and we employ a variety of jet shapes, observables restricted to energy
flow within a jet, to explore this difference. Results from Monte Carlo
generators and arguments based on perturbation theory support the
discriminating power of the shapes we refer to as planar flow and angularities.
We emphasize that for massive jets, these and other observables can be analyzed
perturbatively.Comment: 5 pages and 4 figure
Estimating Effects of Multipath Propagation on GPS Signals
Multipath Simulator Taking into Account Reflection and Diffraction (MUSTARD) is a computer program that simulates effects of multipath propagation on received Global Positioning System (GPS) signals. MUSTARD is a very efficient means of estimating multipath-induced position and phase errors as functions of time, given the positions and orientations of GPS satellites, the GPS receiver, and any structures near the receiver as functions of time. MUSTARD traces each signal from a GPS satellite to the receiver, accounting for all possible paths the signal can take, including all paths that include reflection and/or diffraction from surfaces of structures near the receiver and on the satellite. Reflection and diffraction are modeled by use of the geometrical theory of diffraction. The multipath signals are added to the direct signal after accounting for the gain of the receiving antenna. Then, in a simulation of a delay-lock tracking loop in the receiver, the multipath-induced range and phase errors as measured by the receiver are estimated. All of these computations are performed for both right circular polarization and left circular polarization of both the L1 (1.57542-GHz) and L2 (1.2276-GHz) GPS signals
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