2,694 research outputs found
The reinforcing influence of recommendations on global diversification
Recommender systems are promising ways to filter the overabundant information
in modern society. Their algorithms help individuals to explore decent items,
but it is unclear how they allocate popularity among items. In this paper, we
simulate successive recommendations and measure their influence on the
dispersion of item popularity by Gini coefficient. Our result indicates that
local diffusion and collaborative filtering reinforce the popularity of hot
items, widening the popularity dispersion. On the other hand, the heat
conduction algorithm increases the popularity of the niche items and generates
smaller dispersion of item popularity. Simulations are compared to mean-field
predictions. Our results suggest that recommender systems have reinforcing
influence on global diversification.Comment: 6 pages, 6 figure
Control the entanglement of two atoms in an optical cavity via white noise
Two two-level atoms within a leaky optical cavity is driven by two
independent external optical white noise fields. We investigate how
entanglement between two atoms arises in such a situation. The steady state
entanglement of two atoms is also investigated. A stochastic-resonance-like
behavior of entanglement is revealed. Finally, the Bell violation between atoms
is discussed.Comment: 10 pages, 9 figure
Multi-Label Image Classification via Knowledge Distillation from Weakly-Supervised Detection
Multi-label image classification is a fundamental but challenging task
towards general visual understanding. Existing methods found the region-level
cues (e.g., features from RoIs) can facilitate multi-label classification.
Nevertheless, such methods usually require laborious object-level annotations
(i.e., object labels and bounding boxes) for effective learning of the
object-level visual features. In this paper, we propose a novel and efficient
deep framework to boost multi-label classification by distilling knowledge from
weakly-supervised detection task without bounding box annotations.
Specifically, given the image-level annotations, (1) we first develop a
weakly-supervised detection (WSD) model, and then (2) construct an end-to-end
multi-label image classification framework augmented by a knowledge
distillation module that guides the classification model by the WSD model
according to the class-level predictions for the whole image and the
object-level visual features for object RoIs. The WSD model is the teacher
model and the classification model is the student model. After this cross-task
knowledge distillation, the performance of the classification model is
significantly improved and the efficiency is maintained since the WSD model can
be safely discarded in the test phase. Extensive experiments on two large-scale
datasets (MS-COCO and NUS-WIDE) show that our framework achieves superior
performances over the state-of-the-art methods on both performance and
efficiency.Comment: accepted by ACM Multimedia 2018, 9 pages, 4 figures, 5 table
Increased susceptibility of 129SvEvBrd mice to IgE-Mast cell mediated anaphylaxis
<p>Abstract</p> <p>Background</p> <p>Experimental analyses have identified strain-dependent factors that regulate susceptibility to anaphylaxis in mice. We assessed the susceptibility of the widely used 129SvEvBrd (also known as 129S5) mouse strain to IgE/mast cell-mediated anaphylaxis as compared to BALB/c. Mice were subjected to passive and oral Ovalbumin [OVA]-induced active anaphylaxis. Tissue mast cell, plasma histamine, total IgE and OVA-specific IgE levels and susceptibility to histamine i.v infusion were assessed. Bone marrow mast cell (BMMC)s were examined for Fc<sub>ε</sub>RI, c-kit, degranulation efficiency, proliferation, apoptosis and cytokine profile.</p> <p>Results</p> <p>129S5 mice had significantly increased susceptibility to passive and oral OVA-induced active anaphylaxis. Increased susceptibility to anaphylaxis was associated with increased homeostatic mast cell levels but not OVA-specific IgE or IgG<sub>1 </sub>levels. <it>In vitro </it>analyses of BMMCs revealed no difference in Fc<sub>ε</sub>RI and c-Kit expression, however, 129S5 BMMCs possessed greater proliferative capacity and reduced caspase-3-mediated apoptosis. IgE-BMMC degranulation assays demonstrated no difference in degranulation efficiency. Furthermore, 129S5 mice possessed increased sensitivity to histamine-induced hypothermia.</p> <p>Conclusions</p> <p>We conclude that 129S5 mice have increased susceptibility to anaphylaxis as compared to BALB/c strain and their increased susceptibility was associated with altered mast cell proliferation and homeostatic tissue levels and responsiveness to histamine. Given the wide spread usage of the 129SvEvBrd strain of mice in experimental gene targeting methodology, these data have important implications for studying IgE-reactions in mouse systems.</p
Molecular understanding of the catalytic consequence of ketene intermediates under confinement
[Image: see text] Neutral ketene is a crucial intermediate during zeolite carbonylation reactions. In this work, the roles of ketene and its derivates (viz., acylium ion and surface acetyl) associated with direct C–C bond coupling during the carbonylation reaction have been theoretically investigated under realistic reaction conditions and further validated by synchrotron radiation X-ray diffraction (SR-XRD) and Fourier transformed infrared (FT-IR) studies. It has been demonstrated that the zeolite confinement effect has significant influence on the formation, stability, and further transformation of ketene. Thus, the evolution and the role of reactive and inhibitive intermediates depend strongly on the framework structure and pore architecture of the zeolite catalysts. Inside side pockets of mordenite (MOR), rapid protonation of ketene occurs to form a metastable acylium ion exclusively, which is favorable toward methyl acetate (MA) and acetic acid (AcOH) formation. By contrast, in 12MR channels of MOR, a relatively longer lifetime was observed for ketene, which tends to accelerate deactivation of zeolite due to coke formation by the dimerization of ketene and further dissociation to diene and alkyne. Thus, we resolve, for the first time, a long-standing debate regarding the genuine role of ketene in zeolite catalysis. It is a paradigm to demonstrate the confinement effect on the formation, fate, and catalytic consequence of the active intermediates in zeolite catalysis
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