A Novel BiLevel Paradigm for Image-to-Image Translation

Image-to-image (I2I) translation is a pixel-level mapping that requires a large number of paired training data and often suffers from the problems of high diversity and strong category bias in image scenes. In order to tackle these problems, we propose a novel BiLevel (BiL) learning paradigm that alternates the learning of two models, respectively at an instance-specific (IS) and a general-purpose (GP) level. In each scene, the IS model learns to maintain the specific scene attributes. It is initialized by the GP model that learns from all the scenes to obtain the generalizable translation knowledge. This GP initialization gives the IS model an efficient starting point, thus enabling its fast adaptation to the new scene with scarce training data. We conduct extensive I2I translation experiments on human face and street view datasets. Quantitative results validate that our approach can significantly boost the performance of classical I2I translation models, such as PG2 and Pix2Pix. Our visualization results show both higher image quality and more appropriate instance-specific details, e.g., the translated image of a person looks more like that person in terms of identity

Is a highly pathogenic avian influenza virus H5N1 fragment recombined in PB1 the key for the epidemic of the novel AIV H7N9 in China, 2013?

SummaryBackgroundA novel avian influenza A H7N9 virus that infects humans was identified in China in 2013. This study is the first to comprehensively investigate the characteristics of genomic recombination, rather than reassortment, which has been the subject of investigation in previously reported studies.MethodsNovel avian influenza virus (AIV) H7N9 genome sequences were obtained from the NCBI Influenza Virus Sequence Database and the Global Initiative on Sharing Avian Influenza Database (GISAID) and a representative isolate was subjected to homogeneity analysis. A phylogenetic tree was constructed. Eight segments of the isolate were analyzed to identify segments with recombination events, the corresponding recombination fragments, and breakpoints. The evolutionary history of the recombined fragments was tracked by constructing phylogenetic trees of the recombination fragments.ResultsAmong the eight segments of the novel AIV H7N9 analyzed, only the PB1 segment showed a marked recombination phenomenon, with 11 recombination events; these included five actual recombination events and six possible misalignment artifact recombination events. The most notable was the recombination of a 291-nucleotide (nt) fragment at the 490–780 nt site that was affiliated to a highly pathogenic avian influenza virus (HPAIV) H5N1 (A/tree sparrow/Thailand/VSMU-16-RBR/2005). The phylogenetic tree of the 291-nt recombination fragment on the PB1 segment showed that the novel AIV H7N9 had a close genetic relationship to H9N2 and H5N1.ConclusionsThe novel AIV H7N9 might have reassorted its PB1 segment from H9N2 circulating in China, and this H9N2 PB1 might have been recombined into a highly pathogenic fragment from HPAIV H5N1, which could be the reason for the high fatality rate among patients with AIV H7N9 influenza

Pose guided person image generation

This paper proposes the novel Pose Guided Person Generation Network (PG$^2$) that allows to synthesize person images in arbitrary poses, based on an image of that person and a novel pose. Our generation framework PG$^2$ utilizes the pose information explicitly and consists of two key stages: pose integration and image refinement. In the first stage the condition image and the target pose are fed into a U-Net-like network to generate an initial but coarse image of the person with the target pose. The second stage then refines the initial and blurry result by training a U-Net-like generator in an adversarial way. Extensive experimental results on both 128$\times$64 re-identification images and 256$\times$256 fashion photos show that our model generates high-quality person images with convincing details.Comment: Xu Jia and Qianru Sun contribute equally. Accepted in Proceedings of 31st Conference on Neural Information Processing Systems (NIPS 2017

Natural and Effective Obfuscation by Head Inpainting

As more and more personal photos are shared online, being able to obfuscate identities in such photos is becoming a necessity for privacy protection. People have largely resorted to blacking out or blurring head regions, but they result in poor user experience while being surprisingly ineffective against state of the art person recognizers. In this work, we propose a novel head inpainting obfuscation technique. Generating a realistic head inpainting in social media photos is challenging because subjects appear in diverse activities and head orientations. We thus split the task into two sub-tasks: (1) facial landmark generation from image context (e.g. body pose) for seamless hypothesis of sensible head pose, and (2) facial landmark conditioned head inpainting. We verify that our inpainting method generates realistic person images, while achieving superior obfuscation performance against automatic person recognizers.Comment: To appear in CVPR 201

Widely Targeted Metabolomics Revealed the Dynamic Changes of Metabolites during the Formation of Goose Fatty Liver

To understand the composition and dynamic changes of metabolites during the formation of goose fatty liver, the metabolite profiles of goose liver at three overfeeding stages were analyzed using widely targeted metabolomics. Three 70-day-old Landes geese with similar body conditions from the same batch were selected randomly for slaughter at the early (day 7), middle (day 16) and late (day 25) overfeeding stages, separately. The tip of the larger liver lobe was collected for widely targeted metabolomic analysis. The results showed that: (1) a total of 1 153 metabolites belonging to 19 classes including amino acids, organic acids, nucleotides and lipids were detected in the liver of geese at the three overfeeding stages; (2) principal component analysis (PCA) showed significant differences in the metabolic profiles of goose liver at the three stages, and identified 142 and 92 differential metabolites at the early versus middle stage, and the middle versus late stage, respectively, the major ones being amino acids and their derivatives, as well as organic acids and their derivatives; and (3) Kyoto Encyclopedia of Genes and Genomes (KEGG) metabolic pathway analysis indicated that the pathways involved in fatty acid biosynthesis, vitamin B6 metabolism, linoleic acid metabolism, lysine degradation, arginine biosynthesis, arachidonic acid metabolism and amino acid biosynthesis changed significantly during the formation of goose fatty liver. This study found that most of the differential metabolites were involved in fatty acid synthesis during goose fatty liver formation. Moreover, the contents of transport-related metabolites showed a continuous increasing trend. Findings in this study will not only enrich the theoretical knowledge of poultry liver metabolism, but also provide a theoretical basis for the precise nutritional regulation and efficient production of high-quality goose fatty liver

Shear Stress Induces Phenotypic Modulation of Vascular SmoothMuscle Cells via AMPK/mTOR/ULK1-Mediated Autophagy

Abstract Phenotypic modulation of vascular smoothmuscle cells (VSMCs) is involved in the pathophysiologicalprocesses of the intracranial aneurysms (IAs).Although shear stress has been implicated in the proliferation,migration, and phenotypic conversion of VSMCs,the molecular mechanisms underlying these events arecurrently unknown. In this study, we investigated whethershear stress(SS)-induced VSMC phenotypic modulationwas mediated by autophagy involved in adenosinemonophosphate-activated protein kinase (AMPK)/mammaliantarget of rapamycin (mTOR)/Unc-51-like kinase 1(ULK1) pathway. The results show that shear stress couldinhibit the expression of key VSMC contractile genes andinduce pro-inflammatory/matrix-remodeling genes levels,contributing to VSMCs phenotypic switching from a contractileto a synthetic phenotype. More importantly, Shearstress also markedly increased the levels of the autophagymarker microtubule-associated protein light chain 3-II(LC3II), Beclin-1, and p62 degradation. The autophagyinhibitor 3-methyladenine (3-MA) significantly blockedshear-induced phenotypic modulation of VSMCs. To furtherexplore the molecular mechanism involved in shearinducedautophagy, we found that shear stress could activateAMPK/mTOR/ULK1 signaling pathway in VSMCs.Compound C, a pharmacological inhibitor of AMPK, significantlyreduced the levels of p-AMPK and p-ULK,enhanced p-mTOR level, and finally decreased LC3II andBeclin-1 level, which suggested that activated AMPK/mTOR/ULK1 signaling was related to shear-mediatedautophagy. These results indicate that shear stress promotesVSMC phenotypic modulation through the induction ofautophagy involved in activating the AMPK/mTOR/ULK1pathway.Keywords Vascular smooth muscle cells Intracranialaneurysms Shear stress Phenotypic modulation Autophag