9,859 research outputs found
Graph Convolutional Networks for Text Classification
Text classification is an important and classical problem in natural language
processing. There have been a number of studies that applied convolutional
neural networks (convolution on regular grid, e.g., sequence) to
classification. However, only a limited number of studies have explored the
more flexible graph convolutional neural networks (convolution on non-grid,
e.g., arbitrary graph) for the task. In this work, we propose to use graph
convolutional networks for text classification. We build a single text graph
for a corpus based on word co-occurrence and document word relations, then
learn a Text Graph Convolutional Network (Text GCN) for the corpus. Our Text
GCN is initialized with one-hot representation for word and document, it then
jointly learns the embeddings for both words and documents, as supervised by
the known class labels for documents. Our experimental results on multiple
benchmark datasets demonstrate that a vanilla Text GCN without any external
word embeddings or knowledge outperforms state-of-the-art methods for text
classification. On the other hand, Text GCN also learns predictive word and
document embeddings. In addition, experimental results show that the
improvement of Text GCN over state-of-the-art comparison methods become more
prominent as we lower the percentage of training data, suggesting the
robustness of Text GCN to less training data in text classification.Comment: Accepted by 33rd AAAI Conference on Artificial Intelligence (AAAI
2019
ImageGCN: Multi-Relational Image Graph Convolutional Networks for Disease Identification with Chest X-rays
Image representation is a fundamental task in computer vision. However, most
of the existing approaches for image representation ignore the relations
between images and consider each input image independently. Intuitively,
relations between images can help to understand the images and maintain model
consistency over related images. In this paper, we consider modeling the
image-level relations to generate more informative image representations, and
propose ImageGCN, an end-to-end graph convolutional network framework for
multi-relational image modeling. We also apply ImageGCN to chest X-ray (CXR)
images where rich relational information is available for disease
identification. Unlike previous image representation models, ImageGCN learns
the representation of an image using both its original pixel features and the
features of related images. Besides learning informative representations for
images, ImageGCN can also be used for object detection in a weakly supervised
manner. The Experimental results on ChestX-ray14 dataset demonstrate that
ImageGCN can outperform respective baselines in both disease identification and
localization tasks and can achieve comparable and often better results than the
state-of-the-art methods
Azimuthal anisotropies of reconstructed jets in Pb+Pb collisions at = 2.76 TeV in a multiphase transport model
Azimuthal anisotropies of reconstructed jets [] have
been investigated in Pb+Pb collisions at the center of mass energy
= 2.76 TeV within a framework of a multiphase transport
(AMPT) model. The is in good agreement with the recent ATLAS
data. However, the shows a smaller magnitude than ,
and approaches zero at a larger transverse momentum. It is attributed to the
path-length dependence in which the jet energy loss fraction depends on the
azimuthal angles with respect to different orders of event planes. The ratio
increases from peripheral to noncentral
collisions, and increases with the initial spatial asymmetry
() for a given centrality bin. These behaviors indicate that
the is produced by the strong interactions between jet and the
partonic medium with different initial geometry shapes. Therefore, azimuthal
anisotropies of reconstructed jet are proposed as a good probe to study the
initial spatial fluctuations, which are expected to provide constraints on the
path-length dependence of jet quenching models.Comment: 5 pages, 6 figures, final published versio
PAC-Bayes Analysis of Multi-view Learning
This paper presents eight PAC-Bayes bounds to analyze the generalization
performance of multi-view classifiers. These bounds adopt data dependent
Gaussian priors which emphasize classifiers with high view agreements. The
center of the prior for the first two bounds is the origin, while the center of
the prior for the third and fourth bounds is given by a data dependent vector.
An important technique to obtain these bounds is two derived logarithmic
determinant inequalities whose difference lies in whether the dimensionality of
data is involved. The centers of the fifth and sixth bounds are calculated on a
separate subset of the training set. The last two bounds use unlabeled data to
represent view agreements and are thus applicable to semi-supervised multi-view
learning. We evaluate all the presented multi-view PAC-Bayes bounds on
benchmark data and compare them with previous single-view PAC-Bayes bounds. The
usefulness and performance of the multi-view bounds are discussed.Comment: 35 page
What determines the observational differences of blazars?
We examine the scenario that the Doppler factor determines the observational
differences of blazars in this paper. Significantly negative correlations are
found between the observational synchrotron peak frequency and the Doppler
factor. After correcting the Doppler boosting, the intrinsic peak frequency
further has a tightly linear relation with the Doppler factor. It is more
interesting that this relation is consistent with the scenario that the black
hole mass governs both the bulk Lorentz factor and the synchrotron peak
frequency. In addition, the distinction of the kinetic jet powers between BL
Lacs and FSRQs disappears after the boosting factor is considered.
The negative correlation between the peak frequency and the observational
isotropic luminosity, known as the blazar sequence, also disappears after the
Doppler boosting is corrected. We also find that the correlation between the
Compton dominance and the Doppler factor exists for all types of blazars.
Therefore, this correlation is unsuitable to examine the external Compton
emission dominance.Comment: 15 pages, 6 figures, 1 tabl
CNN-Based Automatic Urinary Particles Recognition
The urine sediment analysis of particles in microscopic images can assist
physicians in evaluating patients with renal and urinary tract diseases. Manual
urine sediment examination is labor-intensive, subjective and time-consuming,
and the traditional automatic algorithms often extract the hand-crafted
features for recognition. Instead of using the hand-crafted features, in this
paper, we exploit CNN to learn features in an end-to-end manner to recognize
the urine particles. We treat the urine particles recognition as object
detection and exploit two state-of-the-art CNN-based object detection methods,
Faster R-CNN and SSD, as well as their variants for urine particles
recognition. We further investigate different factors involving these CNN-based
object detection methods for urine particles recognition. We comprehensively
evaluate these methods on a dataset consisting of 5,376 annotated images
corresponding to 7 categories of urine particles, i.e., erythrocyte, leukocyte,
epithelial cell, crystal, cast, mycete, epithelial nuclei, and obtain a best
mAP (mean average precision) of 84.1% while taking only 72 ms per image on a
NVIDIA Titan X GPU.Comment: The manuscript has been submitted to Journal of Medical Systems on
Jul 02. 201
Scale-Invariant Structure Saliency Selection for Fast Image Fusion
In this paper, we present a fast yet effective method for pixel-level
scale-invariant image fusion in spatial domain based on the scale-space theory.
Specifically, we propose a scale-invariant structure saliency selection scheme
based on the difference-of-Gaussian (DoG) pyramid of images to build the
weights or activity map. Due to the scale-invariant structure saliency
selection, our method can keep both details of small size objects and the
integrity information of large size objects in images. In addition, our method
is very efficient since there are no complex operation involved and easy to be
implemented and therefore can be used for fast high resolution images fusion.
Experimental results demonstrate the proposed method yields competitive or even
better results comparing to state-of-the-art image fusion methods both in terms
of visual quality and objective evaluation metrics. Furthermore, the proposed
method is very fast and can be used to fuse the high resolution images in
real-time. Code is available at https://github.com/yiqingmy/Fusion
Deep Generative Classifiers for Thoracic Disease Diagnosis with Chest X-ray Images
Thoracic diseases are very serious health problems that plague a large number
of people. Chest X-ray is currently one of the most popular methods to diagnose
thoracic diseases, playing an important role in the healthcare workflow.
However, reading the chest X-ray images and giving an accurate diagnosis remain
challenging tasks for expert radiologists. With the success of deep learning in
computer vision, a growing number of deep neural network architectures were
applied to chest X-ray image classification. However, most of the previous deep
neural network classifiers were based on deterministic architectures which are
usually very noise-sensitive and are likely to aggravate the overfitting issue.
In this paper, to make a deep architecture more robust to noise and to reduce
overfitting, we propose using deep generative classifiers to automatically
diagnose thorax diseases from the chest X-ray images. Unlike the traditional
deterministic classifier, a deep generative classifier has a distribution
middle layer in the deep neural network. A sampling layer then draws a random
sample from the distribution layer and input it to the following layer for
classification. The classifier is generative because the class label is
generated from samples of a related distribution. Through training the model
with a certain amount of randomness, the deep generative classifiers are
expected to be robust to noise and can reduce overfitting and then achieve good
performances. We implemented our deep generative classifiers based on a number
of well-known deterministic neural network architectures, and tested our models
on the chest X-ray14 dataset. The results demonstrated the superiority of deep
generative classifiers compared with the corresponding deep deterministic
classifiers.Comment: BIBM 2018 accepte
Multiparticle azimuthal cumulants in p+Pb collisions from a multiphase transport model
A new subevent cumulant method was recently developed, which can
significantly reduce the non-flow contributions in long-range correlations for
small systems compared to the standard cumulant method. In this work, we study
multi-particle cumulants in +Pb collisions at TeV with a multiphase transport model (AMPT), including two- and
four-particle cumulants ( and ) and symmetric cumulants
[SC(2, 3) and SC(2, 4)]. Our numerical results show that is
consistent with the experimental data, while the magnitude of is
smaller than the experimental data, which may indicate either the collectivity
is underestimated or some dynamical fluctuations are absent in the AMPT model.
For the symmetric cumulants, we find that the results from the standard
cumulant method are consistent with the experimental data, but those from the
subevent cumulant method show different behaviors. The results indicate that
the measurements from the standard cumulant method are contaminated by non-flow
effects, especially when the number of produced particles is small. The
subevent cumulant method is a better tool to explore the collectivity in
small systems.Comment: 15 pages, 6 figures; final published versio
A Born-Oppenheimer photolysis model of N_2O fractionation
The isotopically light N_2O produced by microbial activity is thought to be balanced by the return of heavy stratospheric nitrous oxide. The Yung and Miller [1997] method that first explained these trends yields photolytic fractionation factors ∼half those observed by experiment or predicted quantum mechanically, however. To address these issues, we present here a Born-Oppenheimer photolysis model that uses only commonly available spectroscopic data. The predicted fractionations quantitatively reproduce laboratory data, and have been incorporated into zonally averaged atmospheric simulations. Like McLinden et al. [2003] , who employ a three-dimensional chemical transport model with cross sections scaled to match laboratory data, we find excellent agreement between predictions and stratospheric measurements; additional processes that contribute to the mass independent anomaly in N_2O can only account for a fraction of its global budget
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