2,638 research outputs found
Backbone Can Not be Trained at Once: Rolling Back to Pre-trained Network for Person Re-Identification
In person re-identification (ReID) task, because of its shortage of trainable
dataset, it is common to utilize fine-tuning method using a classification
network pre-trained on a large dataset. However, it is relatively difficult to
sufficiently fine-tune the low-level layers of the network due to the gradient
vanishing problem. In this work, we propose a novel fine-tuning strategy that
allows low-level layers to be sufficiently trained by rolling back the weights
of high-level layers to their initial pre-trained weights. Our strategy
alleviates the problem of gradient vanishing in low-level layers and robustly
trains the low-level layers to fit the ReID dataset, thereby increasing the
performance of ReID tasks. The improved performance of the proposed strategy is
validated via several experiments. Furthermore, without any add-ons such as
pose estimation or segmentation, our strategy exhibits state-of-the-art
performance using only vanilla deep convolutional neural network architecture.Comment: Accepted to AAAI 201
Over-Fit: Noisy-Label Detection based on the Overfitted Model Property
Due to the increasing need to handle the noisy label problem in a massive
dataset, learning with noisy labels has received much attention in recent
years. As a promising approach, there have been recent studies to select clean
training data by finding small-loss instances before a deep neural network
overfits the noisy-label data. However, it is challenging to prevent
overfitting. In this paper, we propose a novel noisy-label detection algorithm
by employing the property of overfitting on individual data points. To this
end, we present two novel criteria that statistically measure how much each
training sample abnormally affects the model and clean validation data. Using
the criteria, our iterative algorithm removes noisy-label samples and retrains
the model alternately until no further performance improvement is made. In
experiments on multiple benchmark datasets, we demonstrate the validity of our
algorithm and show that our algorithm outperforms the state-of-the-art methods
when the exact noise rates are not given. Furthermore, we show that our method
can not only be expanded to a real-world video dataset but also can be viewed
as a regularization method to solve problems caused by overfitting.Comment: 10 pages, 7 figure
Sample-Efficient Learning for a Surrogate Model of Three-Phase Distribution System
A surrogate model that accurately predicts distribution system voltages is
crucial for reliable smart grid planning and operation. This letter proposes a
fixed-point data-driven surrogate modeling method that employs a limited
dataset to learn the power-voltage relationship of an unbalanced three-phase
distribution system. The proposed surrogate model is designed using a
fixed-point load-flow equation, and the stochastic gradient descent method with
an automatic differentiation technique is employed to update the parameters of
the surrogate model using complex power and voltage samples. Numerical examples
in IEEE 13-bus, 37-bus, and 123-bus systems demonstrate that the proposed
surrogate model can outperform surrogate models based on the deep neural
network and Gaussian process regarding prediction accuracy and sample
efficiencyComment: Under review in IEEE PES Lette
Transduction of Cu, Zn-superoxide dismutase mediated by an HIV-1 Tat protein basic domain into human chondrocytes
This study was performed to investigate the transduction of a full-length superoxide dismutase (SOD) protein fused to transactivator of transcription (Tat) into human chondrocytes, and to determine the regulatory function of transduced Tat-SOD in the inflammatory cytokine induced catabolic pathway. The pTat-SOD expression vector was constructed to express the basic domain of HIV-1 Tat as a fusion protein with Cu, Zn-SOD. We also purified histidine-tagged SOD without an HIV-1 Tat and Tat-GFP as control proteins. Cartilage samples were obtained from patients with osteoarthritis (OA) and chondrocytes were cultured in both a monolayer and an explant. For the transduction of fusion proteins, cells/explants were treated with a variety of concentrations of fusion proteins. The transduced protein was detected by fluorescein labeling, western blotting and SOD activity assay. Effects of transduced Tat-SOD on the regulation of IL-1 induced nitric oxide (NO) production and inducible nitric oxide synthase (iNOS) mRNA expression was assessed by the Griess reaction and reverse transcriptase PCR, respectively. Tat-SOD was successfully delivered into both the monolayer and explant cultured chondrocytes, whereas the control SOD was not. The intracellular transduction of Tat-SOD into cultured chondrocytes was detected after 1 hours, and the amount of transduced protein did not change significantly after further incubation. SOD enzyme activity increased in a dose-dependent manner. NO production and iNOS mRNA expression, in response to IL-1 stimulation, was significantly down-regulated by pretreatment with Tat-SOD fusion proteins. This study shows that protein delivery employing the Tat-protein transduction domain is feasible as a therapeutic modality to regulate catabolic processes in cartilage. Construction of additional Tat-fusion proteins that can regulate cartilage metabolism favorably and application of this technology in in vivo models of arthritis are the subjects of future studies
PREVALENCE AND CLINICAL AND ECHOCARDIOGRAPHIC PREDICTORS OF DELAYED HYPER-ENHANCEMENT IN SEVERE AORTIC STENOSIS
Class-Attentive Diffusion Network for Semi-Supervised Classification
Recently, graph neural networks for semi-supervised classification have been
widely studied. However, existing methods only use the information of limited
neighbors and do not deal with the inter-class connections in graphs. In this
paper, we propose Adaptive aggregation with Class-Attentive Diffusion (AdaCAD),
a new aggregation scheme that adaptively aggregates nodes probably of the same
class among K-hop neighbors. To this end, we first propose a novel stochastic
process, called Class-Attentive Diffusion (CAD), that strengthens attention to
intra-class nodes and attenuates attention to inter-class nodes. In contrast to
the existing diffusion methods with a transition matrix determined solely by
the graph structure, CAD considers both the node features and the graph
structure with the design of our class-attentive transition matrix that
utilizes a classifier. Then, we further propose an adaptive update scheme that
leverages different reflection ratios of the diffusion result for each node
depending on the local class-context. As the main advantage, AdaCAD alleviates
the problem of undesired mixing of inter-class features caused by discrepancies
between node labels and the graph topology. Built on AdaCAD, we construct a
simple model called Class-Attentive Diffusion Network (CAD-Net). Extensive
experiments on seven benchmark datasets consistently demonstrate the efficacy
of the proposed method and our CAD-Net significantly outperforms the
state-of-the-art methods. Code is available at
https://github.com/ljin0429/CAD-Net.Comment: Accepted to AAAI 202
Identification of long-term prognostic markers in heart failure patients with restrictive filling pattern using doppler echocardiography
Oppositely rotating eigenmodes of spin-polarized current-driven vortex gyrotropic motions in elliptical nanodots
The authors found that there exist two different rotational eigenmodes of oppositely rotating sense in spin-polarized current-driven vortex gyrotropic motions in soft magnetic elliptical nanodots. Simple mathematical expressions were analytically calculated by adopting vortex-core (VC)-rotation-sense- dependent dynamic susceptibility tensors based on the linearized Thiele equation [Phys. Rev. Lett. 30, 230 (1973)]. The numerical calculations of those analytical expressions were confirmed by micromagnetic simulations, revealing that linear-regime steady-state VC motions driven by any polarized oscillating currents can be interpreted simply by the superposition of the clockwise and counterclockwise rotational eigenmodes. The shape of the orbital trajectories of the two eigenmodes is determined only by the lateral dimension of elliptical dots. Additionally, the orbital radii and phases of the two eigenmodes' VC motions were found to markedly vary with the frequency of applied currents, particularly across the vortex eigenfrequency and according to the vortex polarization, which results in overall VC motions driven by any polarized oscillating currents.open8
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