22,476 research outputs found
Feature Extraction via Recurrent Random Deep Ensembles and its Application in Gruop-level Happiness Estimation
This paper presents a novel ensemble framework to extract highly
discriminative feature representation of image and its application for
group-level happpiness intensity prediction in wild. In order to generate
enough diversity of decisions, n convolutional neural networks are trained by
bootstrapping the training set and extract n features for each image from them.
A recurrent neural network (RNN) is then used to remember which network
extracts better feature and generate the final feature representation for one
individual image. Several group emotion models (GEM) are used to aggregate face
fea- tures in a group and use parameter-optimized support vector regressor
(SVR) to get the final results. Through extensive experiments, the great
effectiveness of the proposed recurrent random deep ensembles (RRDE) is
demonstrated in both structural and decisional ways. The best result yields a
0.55 root-mean-square error (RMSE) on validation set of HAPPEI dataset,
significantly better than the baseline of 0.78
Preferential imitation of vaccinating behavior can invalidate the targeted subsidy on complex network
We consider the effect of inducement to vaccinate during the spread of an
infectious disease on complex networks. Suppose that public resources are
finite and that only a small proportion of individuals can be vaccinated freely
(complete subsidy), for the remainder of the population vaccination is a
voluntary behavior --- and each vaccinated individual carries a perceived cost.
We ask whether the classical targeted subsidy strategy is definitely better
than the random strategy: does targeting subsidy at individuals perceived to be
with the greatest risk actually help? With these questions, we propose a model
to investigate the \emph{interaction effects} of the subsidy policies and
individuals responses when facing subsidy policies on the epidemic dynamics on
complex networks. In the model, a small proportion of individuals are freely
vaccinated according to either the targeted or random subsidy policy, the
remainder choose to vaccinate (or not) based on voluntary principle and update
their vaccination decision via an imitation rule. Our findings show that the
targeted strategy is only advantageous when individuals prefer to imitate the
subsidized individuals' strategy. Otherwise, the effect of the targeted policy
is worse than the random immunization, since individuals preferentially select
non-subsidized individuals as the imitation objects. More importantly, we find
that under the targeted subsidy policy, increasing the proportion of subsidized
individuals may increase the final epidemic size. We further define social cost
as the sum of the costs of vaccination and infection, and study how each of the
two policies affect the social cost. Our result shows that there exist some
optimal intermediate regions leading to the minimal social cost.Comment: 8 pages, 7 figure
Laser and Microwave Excitations of Rabi Oscillations of a Single Nitrogen-Vacancy Electron Spin in Diamond
A collapse and revival shape of Rabi oscillations of a single
Nitrogen-Vacancy (NV) center electron spin has been observed in diamond at room
temperature. Because of hyperfine interaction between the host 14N nuclear spin
and NV center electron spin, different orientation of the 14N nuclear spin
leads to a triplet splitting of the transition between the ground ms=0 and
excited states ms=1. Microwave can excite the three transitions equally to
induce three independent nutations and the shape of Rabi oscillations is a
combination of the three nutations. This result provides an innovative view of
electron spin oscillations in diamond.Comment: This manuscript was submitted to Physical Review Letters on June 08,
201
Deterministic Policy Gradients With General State Transitions
We study a reinforcement learning setting, where the state transition
function is a convex combination of a stochastic continuous function and a
deterministic function. Such a setting generalizes the widely-studied
stochastic state transition setting, namely the setting of deterministic policy
gradient (DPG).
We firstly give a simple example to illustrate that the deterministic policy
gradient may be infinite under deterministic state transitions, and introduce a
theoretical technique to prove the existence of the policy gradient in this
generalized setting. Using this technique, we prove that the deterministic
policy gradient indeed exists for a certain set of discount factors, and
further prove two conditions that guarantee the existence for all discount
factors. We then derive a closed form of the policy gradient whenever exists.
Furthermore, to overcome the challenge of high sample complexity of DPG in this
setting, we propose the Generalized Deterministic Policy Gradient (GDPG)
algorithm. The main innovation of the algorithm is a new method of applying
model-based techniques to the model-free algorithm, the deep deterministic
policy gradient algorithm (DDPG). GDPG optimize the long-term rewards of the
model-based augmented MDP subject to a constraint that the long-rewards of the
MDP is less than the original one.
We finally conduct extensive experiments comparing GDPG with state-of-the-art
methods and the direct model-based extension method of DDPG on several standard
continuous control benchmarks. Results demonstrate that GDPG substantially
outperforms DDPG, the model-based extension of DDPG and other baselines in
terms of both convergence and long-term rewards in most environments
Knowledge Transfer Pre-training
Pre-training is crucial for learning deep neural networks. Most of existing
pre-training methods train simple models (e.g., restricted Boltzmann machines)
and then stack them layer by layer to form the deep structure. This layer-wise
pre-training has found strong theoretical foundation and broad empirical
support. However, it is not easy to employ such method to pre-train models
without a clear multi-layer structure,e.g., recurrent neural networks (RNNs).
This paper presents a new pre-training approach based on knowledge transfer
learning. In contrast to the layer-wise approach which trains model components
incrementally, the new approach trains the entire model as a whole but with an
easier objective function. This is achieved by utilizing soft targets produced
by a prior trained model (teacher model). Compared to the conventional
layer-wise methods, this new method does not care about the model structure, so
can be used to pre-train very complex models. Experiments on a speech
recognition task demonstrated that with this approach, complex RNNs can be well
trained with a weaker deep neural network (DNN) model. Furthermore, the new
method can be combined with conventional layer-wise pre-training to deliver
additional gains.Comment: arXiv admin note: text overlap with arXiv:1505.0463
Anomalous decoherence effects in driven coupled quantum spin systems
We discuss anomalous decoherence effects at zero and finite temperatures in
driven coupled quantum spin systems. By numerical simulations of the quantum
master equation, it is found that the entanglement of two coupled spin qubits
exhibits a non-monotonic behaviour as a function of the noise strength. The
effects of noise strength, the detuning and finite temperature of independent
environments on the steady state entanglement are addressed in detail. Pumped
by an external field drive, non-trivial steady states can be found, the steady
state entanglement increases monotonically up to a maximum at certain optimal
noise strength and decreases steadily for higher values. Furthermore,
increasing the detuning can not only induce but also suppress steady state
entanglement, which depends on the value of noise strength. At last, we delimit
the border between presence or absence of steady state entanglement and discuss
the related experimental temperatures where typical biomolecular systems
exhibit long-lived coherences and quantum entanglement in photosynthetic
light-harvesting complexes.Comment: 8 pages, 4 figure
Time evolution of negative binomial optical field in diffusion channel
We find time evolution law of negative binomial optical field in diffusion
channel. We reveal that by adjusting the diffusion parameter, photon number can
controlled. Therefore, the diffusion process can be considered a quantum
controlling scheme through photon addition.Comment: 7 pages, 0 figure
Quantifying Dark Gas
A growing body of evidence has been supporting the existence of so-called
"dark molecular gas" (DMG), which is invisible in the most common tracer of
molecular gas, i.e., CO rotational emission. DMG is believed to be the main gas
component of the intermediate extinction region between A0.05-2,
roughly corresponding to the self-shielding threshold of H and CO.
To quantify DMG relative to HI and CO, we are pursuing three observational
techniques, namely, HI self-absorption, OH absorption, and TeraHz C
emission. In this paper, we focus on preliminary results from a CO and OH
absorption survey of DMG candidates. Our analysis show that the OH excitation
temperature is close to that of the Galactic continuum background and that OH
is a good DMG tracer co-existing with molecular hydrogen in regions without CO.
Through systematic "absorption mapping" by Square Kilometer Array (SKA) and
ALMA, we will have unprecedented, comprehensive knowledge of the ISM components
including DMG in terms of their temperature and density, which will impact our
understanding of galaxy evolution and star formation profoundly.Comment: 4 pages, 5 figures, Proceedings Asia-Pacific Regional IAU Meeting
(APRIM) 201
Switchable Whitening for Deep Representation Learning
Normalization methods are essential components in convolutional neural
networks (CNNs). They either standardize or whiten data using statistics
estimated in predefined sets of pixels. Unlike existing works that design
normalization techniques for specific tasks, we propose Switchable Whitening
(SW), which provides a general form unifying different whitening methods as
well as standardization methods. SW learns to switch among these operations in
an end-to-end manner. It has several advantages. First, SW adaptively selects
appropriate whitening or standardization statistics for different tasks (see
Fig.1), making it well suited for a wide range of tasks without manual design.
Second, by integrating benefits of different normalizers, SW shows consistent
improvements over its counterparts in various challenging benchmarks. Third, SW
serves as a useful tool for understanding the characteristics of whitening and
standardization techniques. We show that SW outperforms other alternatives on
image classification (CIFAR-10/100, ImageNet), semantic segmentation (ADE20K,
Cityscapes), domain adaptation (GTA5, Cityscapes), and image style transfer
(COCO). For example, without bells and whistles, we achieve state-of-the-art
performance with 45.33% mIoU on the ADE20K dataset. Code is available at
https://github.com/XingangPan/Switchable-Whitening.Comment: Accepted to ICCV201
Warm Up Cold-start Advertisements: Improving CTR Predictions via Learning to Learn ID Embeddings
Click-through rate (CTR) prediction has been one of the most central problems
in computational advertising. Lately, embedding techniques that produce
low-dimensional representations of ad IDs drastically improve CTR prediction
accuracies. However, such learning techniques are data demanding and work
poorly on new ads with little logging data, which is known as the cold-start
problem.
In this paper, we aim to improve CTR predictions during both the cold-start
phase and the warm-up phase when a new ad is added to the candidate pool. We
propose Meta-Embedding, a meta-learning-based approach that learns to generate
desirable initial embeddings for new ad IDs. The proposed method trains an
embedding generator for new ad IDs by making use of previously learned ads
through gradient-based meta-learning. In other words, our method learns how to
learn better embeddings. When a new ad comes, the trained generator initializes
the embedding of its ID by feeding its contents and attributes. Next, the
generated embedding can speed up the model fitting during the warm-up phase
when a few labeled examples are available, compared to the existing
initialization methods.
Experimental results on three real-world datasets showed that Meta-Embedding
can significantly improve both the cold-start and warm-up performances for six
existing CTR prediction models, ranging from lightweight models such as
Factorization Machines to complicated deep models such as PNN and DeepFM. All
of the above apply to conversion rate (CVR) predictions as well.Comment: Accepted at SIGIR 201
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