On Data Augmentation for GAN Training Tran, Ngoc-Trung; Tran, Viet-Hung; Nguyen, Ngoc-Bao ...
IEEE transactions on image processing,
2021, Volume:
30
Journal Article
Peer reviewed
Open access
Recent successes in Generative Adversarial Networks (GAN) have affirmed the importance of using more data in GAN training. Yet it is expensive to collect data in many domains such as medical ...applications. Data Augmentation (DA) has been applied in these applications. In this work, we first argue that the classical DA approach could mislead the generator to learn the distribution of the augmented data, which could be different from that of the original data. We then propose a principled framework, termed Data Augmentation Optimized for GAN (DAG), to enable the use of augmented data in GAN training to improve the learning of the original distribution. We provide theoretical analysis to show that using our proposed DAG aligns with the original GAN in minimizing the Jensen-Shannon (JS) divergence between the original distribution and model distribution. Importantly, the proposed DAG effectively leverages the augmented data to improve the learning of discriminator and generator. We conduct experiments to apply DAG to different GAN models: unconditional GAN, conditional GAN, self-supervised GAN and CycleGAN using datasets of natural images and medical images. The results show that DAG achieves consistent and considerable improvements across these models. Furthermore, when DAG is used in some GAN models, the system establishes state-of-the-art Fréchet Inception Distance (FID) scores. Our code is available ( https://github.com/tntrung/dag-gans ).
Magnetite (Fe3O4) nanoparticles (NPs) are attractive nanomaterials in the field of material science, chemistry, and physics because of their valuable properties, such as soft ferromagnetism, ...half-metallicity, and biocompatibility. Various structures of Fe3O4 NPs with different sizes, geometries, and nanoarchitectures have been synthesized, and the related properties have been studied with targets in multiple fields of applications, including biomedical devices, electronic devices, environmental solutions, and energy applications. Tailoring the sizes, geometries, magnetic properties, and functionalities is an important task that determines the performance of Fe3O4 NPs in many applications. Therefore, this review focuses on the crucial aspects of Fe3O4 NPs, including structures, synthesis, magnetic properties, and strategies for functionalization, which jointly determine the application performance of various Fe3O4 NP-based systems. We first summarize the recent advances in the synthesis of magnetite NPs with different sizes, morphologies, and magnetic properties. We also highlight the importance of synthetic factors in controlling the structures and properties of NPs, such as the uniformity of sizes, morphology, surfaces, and magnetic properties. Moreover, emerging applications using Fe3O4 NPs and their functionalized nanostructures are also highlighted with a focus on applications in biomedical technologies, biosensing, environmental remedies for water treatment, and energy storage and conversion devices.
We propose a globally convergent numerical method, called the convexification, to numerically compute the viscosity solution to first-order Hamilton-Jacobi equations through the vanishing viscosity ...process where the viscosity parameter is a fixed small number. By convexification, we mean that we employ a suitable Carleman weight function to convexify the cost functional defined directly from the form of the Hamilton-Jacobi equation under consideration. The strict convexity of this functional is rigorously proved using a new Carleman estimate. We also prove that the unique minimizer of this strictly convex functional can be reached by the gradient descent method. Moreover, we show that the minimizer well approximates the viscosity solution of the Hamilton-Jacobi equation as the noise contained in the boundary data tends to zero. Some interesting numerical illustrations are presented.
Fundamental qualitative properties of the minimum sum-of-squares clustering problem are established in this paper. We prove that the problem always has a global solution and, under a mild condition, ...the global solution set is finite. Moreover, the components of each global solution can be computed by an explicit formula. Based on a new concept of non-trivial local solution, we get necessary conditions for a system of centroids to be such a local solution. Interestingly, these necessary conditions are also sufficient ones. Finally, it is proved that the optimal value function is locally Lipschitz, the global solution map is locally upper Lipschitz, and the local solution map has the Aubin property, provided that the original data points are distinct. The obtained complete characterizations of the non-trivial local solutions allow one to understand better the performance of not only the k-means algorithm, but also of other solution methods for the problem in question.
Backgroud
Pneumonia is one of the leading causes of death in children under 5 years old. Viruses have historically been the most common cause of community‐acquired pneumonia in children. ...Co‐infections in severe pneumonia are more concern by clinicians.
Method
It was a perspective and descriptive study. Real‐time polymerase chain reaction (RT‐PCR) is a modern test that was used to detect many new pathogens, including microbiological co‐infections. RT‐PCR technique was used in this study to investigate the causes of severe pneumonia.
Results
Through the analysis of nasopharyngeal aspiration samples from 95 children with severe community‐acquired pneumonia, the positive RT‐PCR rate was 90.5%. Viral‐bacterial co‐infection accounted for the highest proportion (43.1%), followed by bacterial co‐infection (33.7%), viral infection (7.4%), bacterial infection (6.3%) and the remaining 9.5% was unknown. In the co‐infections groups, the five main bacteria species detected by PCR were Streptococcus pneumoniae, Haemophilus influenzae, MRSA, Moraxella catarrhalis and Mycoplasma pneumoniae.
Conclusion
Antibiotic treatment should focus on detected microbes in cases of severe pneumonia for having a good result.
To gain high hardness, good thermal stability and corrosion resistance, multicomponent TiAlSiN coating has been developed using different deposition methods. In this study, the influence of Al and Si ...on the electrochemical properties of TiN-coated 316L stainless steel as bipolar plate (BP) materials has been investigated in simulated proton exchange membrane fuel cell environment. The deposited TiN, TiAlN and TiAlSiN possess high hardness of 23.9, 31.7, 35.0 GPa, respectively. The coating performance of the TiN coating is enhanced by Al and Si addition due to lower corrosion current density and higher Rcoating and Rct values. This result could be attributed to the formation of crystalline-refined TiN(200), which improves the surface roughness, surface resistance, corrosion performance, and decreased passive current density.
•Multicomponent TiAlSiN hard coating is deposited on 316L SS as bipolar plates for PEMFC.•Electrochemical results indicate that the TiAlSiN coating has excellent corrosion resistance in PEMFC's environment.•The TiAlSiN coating satisfies the quality requirement for BPs (<0.01 Ω cm2).•The TiAlSiN coating should be more conducting in cathode side of a PEMFC.
Folk experiences suggest natural products in
can be effective inhibitors towards diabetes-related enzymes. The compounds were experimentally isolated, structurally elucidated, and tested in vitro for ...their inhibition effects on tyrosine phosphatase 1B (PTP1B) and α-glucosidase (3W37). Density functional theory and molecular docking techniques were utilized as computational methods to predict the stability of the ligands and simulate interaction between the studied inhibitory agents and the targeted proteins. Structural elucidation identifies two natural products: 2-heptyl-1-methylquinolin-4-one (
) and 3-4-(4-methylhydroxy-2-butenyloxy)-phenyl-2-propenol (
). In vitro study shows that the compounds (
and
) possess high potentiality for the inhibition of PTP1B (IC
values of 24.3 ± 0.8, and 47.7 ± 1.1 μM) and α-glucosidase (IC
values of 92.1 ± 0.8, and 167.4 ± 0.4 μM). DS values and the number of interactions obtained from docking simulation highly correlate with the experimental results yielded. Furthermore, in-depth analyses of the structure-activity relationship suggest significant contributions of amino acids Arg254 and Arg676 to the conformational distortion of PTP1B and 3W37 structures overall, thus leading to the deterioration of their enzymatic activity observed in assay-based experiments. This study encourages further investigations either to develop appropriate alternatives for diabetes treatment or to verify the role of amino acids Arg254 and Arg676.
This paper shows an effective method to significantly enhance the isolation of a closely spaced two-port patch antenna, which can be deployed for full-duplex transceivers as well as ...multiple-input-multiple-output (MIMO) systems. Two rectangular microstrip patches are arranged in the E-plane configuration. To achieve high isolation, a grounded stub is positioned between the radiating patches. For validation of the proposed concept, an antenna prototype is fabricated for measurements. The measured data demonstrates that the port-to-port mutual coupling can be suppressed to -50 dB, which is useful in self-interference cancellation for full-duplex communication systems. Compared with the coupled design, the isolation is significantly enhanced by 43 dB with an inter-element spacing of 0.034lambda.sub.c, where lambda.sub.c is a free-space wavelength at the center operating frequency. Regarding MIMO metrics, the antenna also shows good MIMO diversity performance based on an envelope correlation coefficient and a diversity gain.
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•A porous nanocomposite of Cu-MOF was synthesized by facile one-pot solvothermal route.•The spectral, morphological, optical and electrochemical characterization of the newly ...synthesized nanomaterial was carried out and promising results were obtained.•DPV and CV were applied for the detection of mercury ions (canned tuna fish and tap water) under optimized conditions, and LOD for Hg2+is around 0.0633 nM with a linear range of 0.1–50 nM.•The meanwhile, this developed sensor demonstrated satisfactory anti-interference, reproducibility, reliability, repeatability and applicability for detection of mercury ions.
Invisible mercury ion is an incredibly toxic pollutant to the atmosphere. Thus a quick and sensitive detection method is of considerable importance for toxicological assessment, environmental protection and human health. A novel electrochemical sensing system has been developed for the detection of mercury (Hg2+) ions in canned tuna fish and tap water. The sensing platform was developed on the cubic copper-metal-organic framework (Cu-MOF) based nanoparticles. Cu-MOF has a porous architecture with a large, unique surface area that is favorable for mercury ions adsorption and preconcentration. The electrochemical properties of Cu-MOF nanoparticles modified electrode were investigated. Differential pulse voltammetry (DPV) and cyclic voltammetry (CV) were applied for the detection of mercury in 0.1 M phosphate buffer (PB) at pH 9 under ambient conditions. Under optimized conditions, the limit of detection (LOD) for Hg2+ is around 0.0633 nM with a linear range of 0.1–50 nM. Cu-MOF nanoparticles were successfully applied to the analysis of mercury ions in canned tuna fish and tap water. The developed sensor demonstrated satisfactory anti-interference, reproducibility, reliability, repeatability and applicability for the detection of mercury ions. This proof of principle serves as a steppingstone towards promoting ultrasensitive and precise assay for the detection of mercury.
Although stretchable electroluminescent (EL) devices have been the research hotspots for decades because of their enormous market value in lighting sources and displays, fabrication of the ...stretchable EL device through a simple, cost-effective, and scalable method still remains an open issue. Here, a novel all solution-processed method is developed to fabricate a high-performance alternative current electroluminescent (ACEL) device based on copper nanowires (Cu NWs). The Cu NW-based electrode exhibited a low resistance change of less than 10% after 1000 stretching cycles at a tensile strain of 30% and the resistance variation of the electrode in one stretching-releasing cycle was less than 1% at the 1000th. To substantiate suitability for the wearable application, the ACEL device was stretched at a tensile strain of 100% and it retained a luminance of 97.6 cd/m
. Furthermore, the device works well under different deformations such as bending, folding, rolling, and twisting. To the best of our knowledge, this is the first demonstration of Cu NWs applied in a stretchable ACEL, promising cost-effective electrode materials for various wearable electronics applications.
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